no job name from the institute’s photo librarypor_130 320 doi:10.1111/j.1751-8369.2009.00130.x along the beaches of the fjord van keulenfjorden, spitsbergen, lie mounds of white whale (delphinapterus leucas) bones, remains of whale hunting in earlier times. russian whalers in svalbard began harvesting white whales for their blubber and skin in the 18th century. norway and other nations joined in during the latter half of the19th century, when the larger whales they had been targeting became scarce. between 1871 and 1940, norwegian whalers brought in about 9000 white whales. hunting continued into the 1960s, by which time the white whale population was severely depleted. since the species has come under legal protection, white whales—also known as belugas—seem to be making a comeback. pods comprising a few individuals to a few hundred whales are regularly seen around the archipelago. larger pods are spotted from time to time. this photograph was taken by mikael westh hammer at kvitfiskpynten (“white whale point”) in 2000. the norwegian polar institute’s photo library preserves some 90 000 polar-related images captured during the last 135 years, including glass plates and slides, stereo images, print photographs and modern digital photographs. images documenting norwegian activities in the arctic and antarctic comprise the bulk of the collection. scanning the older images and registering newer digital ones is an ongoing endeavour. to date, digital versions of 32 000 pictures are available in a searchable online database at http://sivert.npolar.no/fotoweb/. search words associated with the online images are mostly in the norwegian language; please send an e-mail to bildearkiv@npolar.no for assistance in searching the database. polar research 28 2009 320 © 2009 the author, journal compilation © 2009 blackwell publishing ltd320 http://sivert.npolar.no/fotoweb mailto:bildearkiv@npolar.no on testicular cooling in phocid seals* arnoldus schytte blix, francis h . fay and keith ronald 36 35 34 33 32 31 blix, a . s . , fay. f. h . & ronald, k . 1983: on testicular cooling in phocid seals. polar research 1 n . 5 . . testicular and body core (intra-thoracic) temperatures were recorded in mature male harp seals (pagophihs groenlandicuc) just prior to the mating season. in phocid seals the testicles are outside the abdomen but protected under 7-8 cm of insulating skin and blubber. the temperature of the testicles was found to be 14°c lower than body core temperature. inspection of the veins of the pelvic and hind-flipper reglon of a male ribbon seal (histrrophocafaciata) revealed that the testicles of phocid seals are enveloped in venous plexuses communicating with the veins of the hind flippers. i t is suggested that cooling of the para abdominal testicles of phocid seals is attained by passage of cold blood from the hind flippers through thc extra-testicular plexuses. arnolduc schytte blix, deparfment ofarctic biology and inslitute of medical biology, u n i u e r s i f y of tromso. troms0, norway; francis h . fay, inslintre of marine science, university of alaska, fairbanks. alaska, u . s . a . ; keith ronald, college of biological science, unioersify of guelph, ontario. canada. 231-233. introduction the seals, sea lions, and walruses are placed under two super-families. the otarioidea and the pho coidea. the otarioidea have hind flippers which can turn forward and assist in a sort of four-footed locomotion, while the phocoidea move in a snake-like and/or humping manner close to the ground. for this, or other reasons, the phocoidea do not have a scrotum, while the otarioidea do. in most mammals the testicles lose their sexual potency unless they are kept at a temperature lower than that of body core, and to the best of our knowledge the purpose of the scrotum is to keep the testicles cool. scientists have tended to neglect the importance of phocid seal testicles but the temperature of the sexual glands of fur seals (callorhinus ursinus) is known to be at least 6°c lower than body core temperature (bartholomew & wilke 1956). the purpose of the present study was to deter mine the temperature of the testicles of the harp seal (pagophilus groenlandicus) which, unlike the fur seal, carries its sexual glands against the abdomen under 7-8 cm of insulating blubber. we found that the testicles of the harp seal are cool, and suggest why this is so. presented in part at the 29th alaska science conference, 15-17 august, 1978. material and methods four mature male harp seals (pagophilus groen landicus) were shot while lying on the ice of the gulf of st. lawrence, canada, on 4 march (just prior to the mating season). the weather was sunny, with no wind and an ambient temperature of -7°c. subsequent to an immediate death, body core (intra-thoracic) temperature and the tem perature in the centre of both testicles were meas fig. 1 . body core (intra-thoracic) temperature (upper margin of columns) and the temperature of each of the two testicles (lower margins of columns) of four different mature male harp seals (pagophilus groenlandicrcc) recorded immediately after death. when killed (just prior to the mating season) the animals were lying on the sea ice in calm, sunny weather with an ambient temperature of -7°c. 232 a. s. blix et al. ured by the use of calibrated copper-constantan thermocouples mounted inside 10 cm long hypo dermic needles and connected to a f l u k e s ther mometer (accuracy ?o.l"c) operating o n li batteries. o n e male ribbon seal (histriophoca faciara) carcass was injected with red vinyl resin (turtox. chicago, ill.. usa) into the abdominal aorta and yellow into the plantar digital vein of each hind flipper. t h e carcass was then refrigerated at 4°c for four days before being put into concentrated hydrochloric acid for tissue digestion. tissue a scrotum, and carry their testicles against the abdomen under a thick layer of blubber, their testicles a r e cooler than the body core (fig. 1). the largest difference between testicular and body core temperature was 3.6"c, the average testicular temperature being 33.3 t 0.5 (sd, n = 8). the temperatures of the two glands in each animal, however. often differed, in o n e case by as much as 1.2"c. a t t h e moment we can only suggest that this difference is d u e to lax regulation of testicular temperature in this species. this view is further supported by the fact that average tes fig. 2. photograph of plastic casts of the venous (white) and arterial (grey) vascular beds of the pelvic and hind-flipper regions of a male ribhon seal (hufriophoco faciaru) showing a conspicuous venous connection from the hind flippers to extra-testicular venous plexuses. also shown are the hind leg and ripper hones of the same regions. the remains of the animal lie ventral side up, with the hind flippers extending to the right. the location of the testicles is indicated by arrows. digestion was terminated only when the plastic cast and the skeleton of the animal were left. after rinsing in water the cast was photographed. ticular temperature differed by as much as 1.9"c between individuals. unlike most mature mammals we also found that body core temperature varied by as much as 2.1"c between different animals. moreover. results and discussion average body core temperature was as low as 35.0 t 0.4"c (sd, n = 4), with a liberal range from in spite of the fact that phocid seals d o not have 34.1"c to 36.2'c (fig. 1). this surprisingly low testicular cooling in phocid seals 233 average value and the variability among individ uals compare with data recently obtained by the use of radio telemetry in free swimming seals of the same species (gallivan & ronald 1979). figure 2 shows a cast obtained after injection of coloured vinyl resins into the abdominal aorta and plantar digital veins of a male ribbon seal, which is closely related to the harp seal. the cast shows a conspicuous venous connection between the hind flippers and extra-testicular plexuses, the latter being only partly filled with plastic (fig. 2 ) . on the basis of these results we venture to suggest that the observed cooling of the para abdominal testicles of phocid seals is caused by the passage of cold blood from the hind-flipper veins to extra-testicular venous plexuses. if this is indeed the case, testicle temperature would be even less if the animals, instead of basking in the sun, were swimming in ice water, as such seals are supposed to do during the mating season. references bartholomew, g . a . & wilke. f. 1956: body temperature in the northern fur seal (callorhinus ursmus). j. mamm. 37. 327-337. gallivan. g. j . & ronald. k. 1979: temperature regulation in freely diving harp seals (phoca groenlandica). can. j . zool. 57. 2256-2263. front affecting the distribution of seabirds in the northern bering sea (extended abstract) nancy m . harrison, george l . hunt, jr. and robert t. cooney harrison, n. m . , hunt, g . l . , j r . & cooncy, r. t. 1990: front affecting the distribution of seabirds in the northern bering sea. polar research 8 , 29-31. nancy m . harrison, nature conseruancy council, 17 rubitlaw terrace, aberdeen abi 1xe. scotland; george l . hunt, j r . , dept. of ecologv and euolutionary biology, university of california, irvine, c a 9271 7, u . s . a . ; robert t . cooney. institute of marine sciences, university of alaska, fairbanks. a k 99701, u . s . a . ; may 1989. we observed seabirds aggregated at a front mark ing the boundary between two water masses in the bering sea. least auklets (aethia pusilla) were most abundant at the front; surface-feeding species including northern fulmars (fulmarus glacialis), black-legged kittiwakes (rissa tri dactyla) and red phalaropes (phalaropusfuscus) were also present. the study area, just north of gambell on st. lawrence island, was visited during the breeding seasons (july-august) of 1984 to 1986. the front separates the well mixed oceanic water of the anadyr current from layered water resident on the shelf. the anadyr current passes up the west side of the northern bering sea and through the bering strait (coachman et al. 1976). the shelf is shallow north of st. lawrence island (30-50m) and the water of the current is mixed from top to bottom. the bering shelf water is characterized by strong vertical temperature, salinity and den sity gradients. the physical structure of the front was studied by measuring changes in temperature, salinity and density using a ctd probe. to assess the distribution of birds, continuous counts were made of all birds on the water in a 300 m arc from bow t o beam. a small collection of least auklets and more extensive dietary studies from con current research nearby showed that large calanoid copepods dominated the diet of the least auklet (hunt et al. 1989). zooplankton biomass in the water and the vertical distribution of zooplankton was determined using a biosonics echo-sounder (200 kilohertz) and echo integrator. integrations of biomass were made each tenth of a nautical mile with vertical intervals of 2 m from 5 m below the surface t o the bottom. in order to identify the animals responsible for the acoustic scattering plankton was sampled by making vertical tows with a net (1 m diameter, 505 micron mesh). net tows identified the calanoid fig. i . temperature profile and least auklet numbers for a transect extending due north of gambell, st. lawrence island. station 2 was in the middle of the front as indicated by the thermocline reaching the surface. the peak in bird numbers is just to the south of the front where the thermocline is very shallow. 30 n . m . harrison et al. copepod neocalanus plumchrus as the dominant pelagic zooplankton in the study area. in 1984, large numbers of least auklets were observed at the front along the margin of anadyr water. in fig. 1 the anadyr water can be identified (on the far left) as the cold, mixed area with similar temperatures at the top and bottom. the bering shelf water has a strong thermocline (fig. 1). least auklets, which had been nearly absent over the mixed anadyr current, were extremely abundant at this front. over the bering shelf water numbers declined with distance from the front. because the anadyr current has a meandering path along the international border between the u.s.a. and the u.s.s.r., we were unable to find the front on the east side of the political border on several runs of our original transect north of gambell in 1985 and 1986. however, other meanders of the anadyr current were located within 20 km northeast of the original transect. the structure of the front was similar at each crossing. one crossing of the front in 1985 is shown in fig. 2 . this figure illustrates the front at a much stolion station stolion station station station 136 137 i 3 r iai i x a ian .. ._. 1.97 1.61 10 1.97 1.56 1.66 n 1.72 1 1.22 1.51 1.70 1.18 fig. 2. temperature profile and acoustic biomass for another crossing of the front. high plankton biomass was at the surface over the shallow thermocline. smaller scale, and pictures only 4 nautical miles of the transect. above the shallow thermocline near the surface expression of the front there were concentrations of zooplankton, with a biomass as high as 16 g/mz. in the mixed anadyr water there was virtually no plankton (< 2 g/m2). plankton levels fell with distance away from the front into t h e structured bering shelf water. in 1986, a particularly strong convergence was located. there was little wind, and distinct streak ing on the water. among the 108 surface-feeding birds counted along the streaks were fulmars, black-legged kittiwakes and red phalaropes which were all sitting on the water pecking at the surface. the acoustic record identified a very sharp peak in plankton biomass (11 g/m2) in the upper 10 rn (range of 5 to 10 m) directiy in line with the convergence streak (the areas t o either side having <1 g/m2 in the same depth range). these species have distinctly different require ments than least auklets. requiring prey within the top few cm. the front otherwise showed a familiar pattern of birds, with hundreds of least auklets on the water over the area with the shallowest ther mocline. their numbers dropped to 0 over the mixed anadyr water. again we observed shallow peaks in biomass in the structured water, with the greatest peaks nearest the front. some seabird species appear to require a con centration of prey, rejecting dispersed prey. aggregations of prey at fronts are particularly important for these predators. there was fre quently a higher prey density at the front north of gambell. although anadyr water is high in nutrients, densities of plankton are low and dispersed by turbulence. nutrients are entrained across the front into the nutrient poor surface layer of the stratified water. here phytoplankton are held in the euphotic zone resulting in an enhanced production near the front. the very large biomass of zooplankton sometimes seen there is probably in part a response to this pro duction. calanoid copepods are known to respond to strong property gradients, and often concentrate at the thermocline in the north pacific (barro clough et al. 1969). their behavioural response to the physical structure near the front is likely to be the direct explanation of why they are con centrated near the surface there. this distribution near the surface appears t o be favourable for least auklets. the term ‘front’ describes a variety of physical phenomena at varying temporal and spatial scales, and we cannot generalize that fronts are important for least auklets. however, our obser vations here support our other data on this species at sea: they appear to selectively forage at hydro graphic structures where prey accumulate near the surface (hunt et al. 1989). in this case the circulation at a front forced the thermocline up towards the surface and resulted in shallower prey concentrations. front affecting the distribution of seabirdr 31 references barroclough, w. e . , lebrasseur, r . j . & kennedy, 0. d . 1969: shallow scattering layer in the subarctic pacific ocean: detection by high-frequency echo sounder. science 166,611 613. coachman, l. k . , aagaard, k . & tripp, r . b . 1976: bering strait: the regional physical oceanography. univ. of wash ington press, seattle. 186 pp. hunt, g . l . , j r . , harrison, n . m. & cooney, r. t. 1989: foraging of least auklets: the influence of hydrographic structures and prey abundance. studies in avian biology (in press). research note observations on the wader populations at ny-alesund, spitsbergen, 1982 hans meltofte, fridtjof mehlum and john frikke meltofte, h., mehlum, f. & frikke, j . 1983: observations on the wader populations at ny-alesund. spitsbergen, 1982. polar research 1 n . s . . 211-213 (notc). hans meltofte, zoological museum, uniuersitetsparken 15, dk-2100 copenhagen, denmark; fridtjof mehlum, norsk polarinstitutt, rolfstangueien 12, 1330 oslo lufthaun, norway; john frikke, vildtbiologisk station, kald, dk-8410 rmnde, denmark. during the summer of 1982 waders, charadriidae, were recorded regularly by fm in the station area of ny-alesund (78"55'n, ll"56'e). from 6 to 18 july waders were censused by h m and j f in a 6.32 kmz area around ny-alesund (fig. 1). parts of the area were covered each day and all birds seen were mapped. all suitable habitats were covered within a distance of 25-50111 at least once, and early snow-free ridges were surveyed especially. the habitats are briefly described by bengtson (1975a) and mapped in detail by brattbakk (1981). the first purple sandpiper calidris maritima appeared on 29 may, the first turnstone arenaria inrerpres on 2 june, the first sanderling calidris a h a on 5 june, the first dunlin calidris alpina on 6 june, the first grey phalarope phalaropusfulicanus on 7 june, the first ringed plover charadrius hiaticula on 8 june, and the first red-necked phalarope phalaropus lobafus was seen on 14 june. in early june when snow-free vegetated areas were found practically only in the station area, the number of pre-breeding waders reached a peak with 120 purple sand pipers and 30 sanderlings o n 6 june, whereas no concentrations occurred in the other species. a number of purple sandpipers (15-20) stayed in the station area until extensive melt took place around 2&25 june, whereupon they dispersed. small groups of knots calidris canutus were present in the period 18 june to 6 july. nests or newly hatched young were found of two pairs of ringed plovers, four turnstones, six purple sandpipers, one dunlrn, ten grey phalaropes, and one pair of red-necked phal aropes (fig. 1). the total number of territories was estimated (table 1) based on finds of nests and young. and on singing or otherwise displaying males and pairs. the extent to which non-breeders were involved is unknown. the purple sandpipers posed special problems, as they nor mally do not give alarm calls or react in other ways to human activity in or close to the territory. the flushing distance of incubating birds was normally only 1-5 m (bengtson 1970). the table 1. numbers of wader broods (1967 and 1973) and territories (1981 and 1982) recorded in the census area at n y h r s m d . census year area 1967 1973 1981 1982 1982 (3.1) (3.1) 3.70 3.70 6.32 charadrius hiaticula arenaria interpres calidris maritima calidris alpina calidris alba phalaropus fulicarius phalaropus lohatus 3 0 8 0 0 4-5 0 4-5 3-5 13-14 1 0 2&25 1-2 2-3 3 13-15 2 0 15-20 1-2 2-3 4 1x-21 2 0 15-20 1-2 total 15-16 22 42-52 3 6 4 5 42-52 for 1982 both totals from the area censused during the three previous studies and the grand total for all the area are given. 1967 and 1973 data from bengtson (1975a). according to the new maps, however, the area censused by bengtson was 4.7 km2. 212 hans meltofte, fridtjof mehliim & j o h n frikke 0 ringed plover s turnstone b purple sandpiper v dunlin red-necked phalaropl 0 nest found 0 pulli found limit of census area limit of eastern part 1 km fig. 1. the census area at ny-alesund nith the breeding sites and territories plotted. the eastern part of the area, censused in 1967. 1973. and 19ri. is separated with a dotted line. grey phalaropes are not included. the area censused in 1967 and 1973 include5 about one square kilometre more of the alluvial hats east of the indicated area. estimated total of l & ? l territories is based on nests and broods found and on singing or otherwise displaying males or pairs. but some birds were only registered once. and at .%1 of the six nests/hroods found. no song or other activities were ever recorded. hence. the figure is probably a minimum. and xl30 territories is perhaps a better estimate, giving 3.2-4.7 pairs per square kilometre to achieve a more exact and reliable figure for this species. i t is nccessary to follow the population from dispersal to the territories until after hatching (meltofte 1976, 1979). more birds may be present in a favourable area dunng the territoq estab lishing phase than later o n . but it is important to know amhere the birds settle to make it easier to trace them during the incubation period. the 'successful' pairs are easy to register after hatching. but the situation gets more difficult when broods start wandering widely over the area. the most fixed territories are plotted i n fig. i . the purple sandpiper appeared to be the only species breeding extensively outside the station area. while all other wader species concen trated at the early snow-free and extremely fertile station area. this is the only species for which a density calculation can he made uith certainty. therefore. one ringed plover clutch hatched on 19 jul) (first young either observed or estimated from measurements of pulli found). four turnstones o n 5. 7. 12. and 22 july. three purple sandpipers on 12. 15. and 22 j u l b . four gre) phalaropes i n mid july (the first on 7 july). and one red-necked phalarope on 18 july. the 1982 season seems to have been a relatively early season (see bengtson 1968, 197sb). while hatching dates in 1981 apparently were somewhat later (mehlum unpubl.). the eastern 3.70km2 of the area were even censused for wader broods during the first half of august in 1967 and 1973 (bengtson 197sa). and breeding territories and broods were mapped in the same area in june and july 1981 (mehlum unpubl.). the results of the four studies are not readily com parable. i n 1967 and 1973 only successful breeding pairs were included. while all territories and nests were included in 1981 and 1982. considering these differences, the results are in fair correspondence. except for the grey phalaropes and to some extent the turnstones. breeding in larger numbers at the station noa. than at the time when the first two censuses took place. the grey phalaropes may take advantage of the protection given by the large colony of arctic terns sterna purudisaeu in the station area at ny-alesund. this colony increased from some 80 pairs in 1967 (bengtson 1968. 1971). to about 300 pairs in 1981 and 1982. the dunlin has been seen breeding at ny aiesund on a few previous occasions ( k m s & byrkjedal 1981), while the red-necked phalarope has never before been found breeding this far north in svalbard. the population density of purple sandpipers in this area is significantly higher than reported from elsewhere in svalbard. on the extensive foreland areas at nordenskiiild land. the breeding density was estimated to 0.3 pairs per square kilometer in 1975 (kilas 8: byrkjedal 1981). in adventdalen 1.5 pairs wader populations at ny-alesund 213 per square kilometre were reported in 1976 (alendal et al. 1982). alendal et al. (1982) estimated 0.6 pairs per square kilometre on reinsdyrflya on the northwestern part of spits hergen in 1976. even lower densities have been found on frans josef land where p. s . tomkovich (pers. comm.) found 12-14 pairs of purple sandpipers on 420 kmz of tundra on graham bell island in 1981. considerably higher densities are found in west greenland, where the purple sandpiper dominates together with the red-necked phalarope. here joensen & preuss (1972) found about five pairs per square kilometre near prcbven at disco bay in 1965. the relative abundance of wader species breeding in green land and svalbard is different in the two areas. the ringed plover. the turnstone. the knot, the dunlin, and the sanderling dominate in northeast greenland. while the purple sandpiper is only found along the outer coasts (meltofte unpubl.). the outer coasts of northeast greenland where the latter breed apparently have ambient conditions similar to those along much of the barren, cool, foggy, and late-thawing coasts of svalbard (meltofte er al. 1981). what is prohably of more direct signifi cance, however, is the relatively sparse and late emerging invertebrate life on the tundras of svalbard, compared to green land. a striking fact is that waders other than the late-breeding purple sandpiper found at ny-alesund concentrated in the relatively early snow-free and extremely fertile station area, while the same species breed extensively over the tundras of northeast greenland. the vegetation is indeed more lush in the ny-alesund region than in most areas in high arctic green land. and on most of the coasts of northern and eastern svalbard. the breeding schedule of the waders at ny-alesund is not much different from that found in similar late-thawing areas in high arctic greenland. based oji quantitative studies of the invertebrate life in dif ferent habitats at ny-alesund and on analyses of the stomach contents of purple sandpipers, bengtson & fjellberg (1975) conclude that the food of the tundra is so limited that the purple sandpiper t o a large extent is dependent on feeding possibilities in the littoral zone, hence, the limited food resources on the tundras of svalbard seem to he the main reason for the relatively poor wader fauna of this archipelago, as compared to most other arctic areas references alendal, e . , erikstad. k. e . & kills. j. a . 1982: the bird fauna in the ne part of northwest-spitsbergen national park a census of breeding birds o n high arctic tundra. fauna 35, 106-113. (norwegian with english abstract). b e n g t s ~ n . s.-a. 1968: breeding behaviour of the grey phal arope in west spitsbergen. v6r figeloarld 2 7 , 1-13, bengtson, s.-a. 1970: breeding hehaviour of the purple sand piper calidris maririma in west spitsbergen. ornis scand. i , 17-25. bengtson, s.-a. 1971: breeding success of the arctic tern. sterna paradisaea (pontoppidan), in the kongsfjord area, spitsbergen in 1967. norw. j . zool. 19, 77-81. bengtson. %-a. 1975a: tetthet av hekkende vadere p i tun draen omkring ny-alesund, svalbard. norsk polarinstiturr a r b o k 1973, 175-178. bengtson, s.-a. 1975b: observations on the breeding biology of the purple sandpiper, calidris maridma, on svalbard. fauna 28, 81-86. (norwegian, with english summary ) bengtson, %-a. & fjellberg. a . 1975: summer food of the purple sandpiper (calidris rnorifima) in spitsbergen. arrarre bratthakk, i . 1981: vegetariomkart i :10,000 br#ggerhalo0ya sualbard. university of trondheim. joensen, a . h . & preuss, n. 0. 1972: report on the orni thological expedition to northwest greenland 1965. meddr. grmnland 191 ( 5 ) . 58 pp. k i l l s , j. a . & byrkjedal, i . 1981: the statusof breeding waders charadrii in norway including svalbard. proc. second nordic congr. ornithol. 1979, 57-74. meltofte, h. 1976: ornithological observations in southern peary land, north greenland, 1973. meddr. grmnland 205 meltofte, h. 1979: the population of waders charadriidae at danmarks havn. northeast greenland, 1975. dansk orn. foren. t i h s k r 73. 69-94. meltofte, h.. elander, m., hjort, c. 1981: ornithological observations in northeast greenland between 7490' and 76"00' n. lat. 1976. meddr. grgnland, biosci. 3 , 53 pp. 8, 1-6. ( i ) , 57 pp. research note fishing arctic foxes azopex zagopus on a rocky island in west greenland sussie mqller nielsen nielsen. s. m. 1991: fishing arctic foxes alopex lugopur on a rocky island in west greenland. polar research 9(2). 211-213. on a small barren island in disko bay, west greenland, 195 hours were spent observing arctic foxes at their den and the nearby coast. their main food was found to be live, caught fish, and the activity of the foxes was correlated with the tidal height. s. m . nielsen, arctic station, uniuersity of copenhagen. dk-3953 godhaun. greenland. introduction although previously published works contain brief and des ultory remarks indicating that the arctic fox alopex lagopus is capable of catching live fish (cranz 1765; fabricius 1780; sarmundsson 1939; pedersen 1959). only kaikusalo (1971) de scribes actually having seen a fox unsuccessfully trying to catch a fish. hence, no detailed description of fishing arctic foxes has been given to date. this paper aims to describe how arctic foxes catch live fish, how efficient they are, and to what extent they can iely on this food source. study area the study took place on a 2 kmz island (0-70 m a.s.1.) that belongs to the archipelagos of kronprinsens ejland. disko bay (69n 53 w). west greenland. the island is formed by precambrian rocks, and except for two small beaches the coast line (9 km) is rocky (1/3 steep cliffs). the distance to the nearest island is 1.8 km. at low tide several rock pools with rich seaweed vegetation (mainly fucur disticur) are uncovered. the tidal fluctuation varied during june and july from 0.1 m to 2.7 m (mean 0.8 m). the island is sparsely vegetated by dwarf shrub heath, mainly crowberry empetrum hermaphroditum. herb and marsh vegetation is found in narrow zones around ponds. terrestrial animal life is poor (see also porsild & ostermanna 1921). n o signs of other mammals were found, and the only breeding bird species observed was the snow bunting plec trophennr niualis. along the coast, however, several species of sea birds were foraging and some were seen resting on the cliffs almost daily. materials and methods the observations were initiated 22 june 1990 when a family of dark phased (“blue”) foxes was located. a t the timgof discovery the family consisted of 2 adults (nursing female and male) and 6 cubs (4-5 weeks old). the two adults were easily identified by distinct fur characteristics. and sex-determination of the male was made at close hand. the family was still intact on 30 july when the last observations were made. within this period the island was visited for ten 2 4 h o u r periods. in total. 195 hours were spent observing both the den and about 200 m coastline with rock pools. the observations were made from cliffs at about l o m a . s . l . . 7 0 m f r o m t h e d e n , a n d 100mfromthecoast. the equipment consisted of binoculars (10 x 50) and a watch. the time (to the nearest minute) was recorded when an adult fox began to forage between the coastal rocks and the moment it stopped or went out of sight. also recorded were the moment when a fish was caught and when an item was delivered to the cubs. fish and other items were identified when possible. i n addition, sleeping sequences were noted: the time when an adult went to sleep as well as the length of time it slept were recorded. the results are related to tide tables for kronprinsens eiland 1990. results at least one adult fox was in focus for 39 hours and 14 minutes (20% of the observation time). the adults were in sight simul taneously for 39 minutes, so the total observation time of individual adult foxes was 39 hours and 53 minutes (the male was observed for 24 hours and 7 minutes, the female for 15 hours and 32 minutes, and there were 14 minutes when the sex could not be recognized). altogether the two adults foraged at the coast for 6 hours and 59 minutes (range 1-37 minutes) distributed over 32 sequences. within this time a minimum of 25 fish were caught (mean 17 minutes per catch and 0.8 fish per sequence). the male caught 9 fish in 4 hours and 13 minutes (13 sequences; mean 28 minutes per catch and 0.7 fish per sequence). the female caught 16 fish in 2 hours and 46 minutes (19 sequences; mean 10 minutes per catch and 0.8 fish per sequence). one morning when conditions for fishing may have been especially favourable. the female caught 6 fish in 28 minutes. 212 siissie m d l e r nielsen 70 a -- i m 6 r; r 2 tidal height fig. i . the proportion ( % ) of the ohservation time thc adult l o w \ spent foraging it1 t h c cciast ( a ) and slccping ( b ) in relation t u t h e tidal height observation timc in minutes: 314(1 (u.(k ( 1 . 5 m ) , 4 0 j 5 ( ~ l 5-1 llm);2270(1.(k1.5rn);xzs~l.i-2 0 i n ) a n d 300 (2.ll-2 5 m) t h s ioxci were <c'cn searching for food at the coast only when the tide was helow i m. and the amount of timc spent foraging was inver\cly proportional to the tidal height (fig. i a ) . o n the contrary. 8 4 5 of thc time \pent slccping ( a l w a l s in the cliffs ahovc the d e n ) occurrcd hhen the tidc wai ahovc 1 m (fig 1b). thc adult foxc, were o b w r \ c d sleeping for a total of i4 hour< and 4 minutes ( t h c malc was observed slccping for a total of 8 hour< and 5 5 ininutes and the female for 5 hours and 9 minute\). thc mean slccping timc wa\ 34 minutes (range j-105. n = 2 5 ) . when the foxes travelled along the coast they foraged eithcr h\ turning scdwecd u i t h a front paw and gleaning amphipode< from the algae. or b) searching for fish in cracks and rock pools on thcir way whcn fishing. thc fox would stand with its hindquarters on the edge of a pool. the tail pointing vertically upwards. and with mo\t of i t s head and forepart hidden hetween rocks and seawccd. during thc catch, the fox twisted its tail from side to fir. 7 adult f o x catching live fish in a rock pool (field sketch). sidc to kccp its balance. these fishing scenarios lasted only for a few seconds. after which the fox often appeared with a wrig fling fish in its mouth (fig. 2). t h e fox either delivered thc fish (often still wriggling) to the cubs, ate it on the way hack to the den. o r left i t on a rock while continuing to fish. fivc times a fox was seen depositing a fish between rock5 o r in ii m a l l holc ( i 0 to 15 cm deep) in the nearest surroundings o f the d e n . these h o b were dug with the front paws. and after depositing t h e prey the fox covered the holca by pushing and patting the earth down with its nose. thc foxc5 were not sccn entering the water t n catch tkh: they were usually wet only on the head and torcpart when they returned from fishing. they often spent ronir timc drying thcir coats by ruhhing thcinsclvcs against t h e vegetation on one occasion thc male returned t o the den waking wet. with a lump-sucker cyclopfmcs /uwipits. indi cating that it might have hccn necessary for him to cntcr the water to catch the large f s h . after delivering the fish to the cubs. he shook the water off his coat and ruhbcd against the vcgctation. only once was a fox seen swimming hctwcen the \kerrics of the c o a s ( a distance of about 2 m). hut i have seen arctic foxes swim across a 10 ni wide river o n several occasions i n anothcr location. they are steady hut not fast swimmers. i)ing fairly high in the water (head and back dry and the tail floating behind). partly held up by the dense and puffy coat. immcdiately after swimming. the fox shakes the water from the coat. often while it is still moving o n . of 40 items delivered to the cuhs ( 2 3 fish. i snow bunting. 1 wing of il raven curous corux and 15 not identified). most were delivered at low tide ( i l rn) and most items delivered at high tide had been dug up from prey dcposirs near the den (table i ) . i n all. 36 fish were seen caught, delivered to the cuhs, or both: i y banded gunnels pholis fnvciurw, 2 lump-suckers, 1 father-lasher myoxocephulus sp. and 13 not determined. fishing arctic foxes alopex lagopus on n rocky island in west greenland 213 tuhle i . total observation time at low tide (< 1 m) and high tide (> 1 m), the number and frequency of items delivered to the cubs and of items dug u p and delivered. obs. time i n minutes (%) items delivcred no. no./hour items dug u p and delivered (9; of items delivered) tidal height: < i m > l m total 7195 (61) 11700 (100) 4505 (39) 32 8 40 0.3 0.1 0.2 discussion the present observations document that arctic foxes are able to catch live fish with a high degree of success. they were not seen. however, alluring the fish with a paw as described by cranz (1765) and fabricius (1780). that hunting took place mainly at low tide and that live. caught fish comprised the most important food source for the fox family during the observation period are supported by the following facts: 1 ) prey delivered to the cubs consisted primarily of fish; 2 ) prey were delivered mainly at low tide; 3) most prey delivered at high tide were dug up from deposits; 4) the bulk of the sleeping time occurred during high tide. a number of wings of sea birds found at the den had probably been taken from a nearby hut where several leftovcrs from hunters lay scattered. including wings of sea birds of the same species as found at the den (the hut was not in use during the study period). arctic foxes inhabit several small islands in the disko bay, and fishing foxcs may be a common. hut overlooked, phenom enon. in iceland remains of lump-sucker is commonly found at fox dens (hersteinsson 1984). the present island is much smaller than arctic fox home ranges measured by radiotracking elsewhere (marc than 8 km?) (eherhardt et al. 1982; hersteinsson & macdonald 1982: birks & penford 1990). a rocky coastline may therefore be a richer habitat for arctic foxes than both inland and heach areas due to the foxcs’ ahility to catch live fish with high efficiency. this may be an important new aspect in the understanding of the distribution and ecology of the arctic fox. acknowledgements. for company and assistance in the field i want to thank t. b. berg, a . caulfield and 0. frimer. special thanks go to a . jensen for her efforts and participation in the field. i am also grateful to p. provencal for translating parts of factno groenlundicu (fabricius 1780) from latin to danish. and to h . walhovd and l . albright for various help. the manuscript benefitted from criticism and suggestions from 0. frimcr and p. mdgaard and was kindly read by e . muus. the study is supported by grants from the commission for scientific research in greenland and thc carlsberg foundation. references birks. j . d. s . & penford. n . 1990: observations on the ecology of arctic foxes alopex lugopus in eqalummiut nunaat. west greenland. meddr. grmnlund. biosciertce 3-7. 26 p p . cranz, d. 1765: hisrorie oon grdnlund. leipzig. ebcrhardt, l . e . . hanson, w. c.. bengtson. j . l.. garrott, r . a. & hanson. e. e. 1982: arctic fox home range charac teristics in an oil-development area. j . w i l d . munuge. 46. 183190. fdbricius, 0. 1780: fuicrtu groerf/undicu. hafnia & lipsiac. hcrsteinsson, p . 19x4: behavioural ecology of the arctic fox alopex lugopus in iceland. unpubl. ph.d. thesis. university of oxford. hersteinsson. p. & macdonald. d. w. 1982: some comparisons between red and arctic foxes. vulpes uulpes and alopex lagopus. as revealed by radio tracking. synip. zool. soc. lond. 49. 259-289. kaikusalo. a . 1971: om fjalrlvens (alopex lagopus) for plantning i nordvastra enontkis i finska lapmarken. suornen riisru. 23, 7-16. (translation by t. forsgren in finsk vilrforsktiing 1974, 14s156). pedersen. a . 1959: der eisfuchs alopex lugoptis linnp. zic mens verlag, wittenberg-lutherstadt. porsild. m. p. & ostermann, h . 1921: godhavndistrikt. m e d d r . gr@nlund i . 2 7 s 3 4 1 . szmundsson. b. 1939: mammalia. pp. 1-38 in frederiksson. a. & tuxen. s . 1. (cds.): the zoology o f l c e l u n d iv. vol. 76. copenhagen and reykjavik. composition of leucocytes in peripheral blood of patagonian toothfish (dissostichus eleginoides, smitt, 1898) (nototheniidae) research note composition of leucocytes in peripheral blood of patagonian toothfish (dissostichus eleginoides, smitt, 1898) (nototheniidae) ilya i. gordeev a, daniil v. mikryakov b, lyudmila v. balabanova b & veniamin r. mikryakov b alaboratory of pacific salmons, russian federal research institute of fisheries and oceanography, moscow, russia; bi.d. papanin institute for biology of inland waters, russian academy of sciences, yaroslavl region, russia abstract the composition of leukocytes in the patagonian toothfish (dissostichus eleginoides smitt, 1898), caught in the scotia sea at a depth of more than 1000 m, was studied. cells with various morphofunctional characteristics and cell structure were found. lymphocytes were predominant, followed by, in decreasing order, eosinophils, monocytes, blast forms and neutrophils. the composition of leukocytes in the patagonian toothfish consists of the same types of leukocytes as the earlier studied antarctic toothfish (dissostichus mawsoni norman, 1937), but the percentage of white blood cells in the leukocyte formula differs between the two species. keywords patagonian toothfish; blood; nototheniidae; leukocytes introduction leukocytes are polymorphic and polyfunctional blood cells that perform a several physiological and immunological functions. they are involved in defending the body from foreign substances and they ensure fish adaptation to biotic and abiotic factors and immunity to parasites (mikrjakov & balabanova 1979; mikrjakov 1991; secombes 1996; galaktionov 2005; van muiswinkel & vervoornvan der wal 2006). the main types of white blood cells in fishes are lymphocytes, monocytes, neutrophils, eosinophils and basophils (ellis 1977; ivanova 1983; parish et al. 1986; točilina 1994; gruško et al. 2009). the composition of leukocytes reflects the specific and ecological features of fish and the ratio of some cell types reflects the functional state of the organism, as well as the pattern of the effect of biotic and abiotic factors (ellis 1977; parish et al. 1986; točilina 1994; mikrjakov et al. 2001). the composition of leukocytes in fish has been most comprehensively studied in representatives of common and widely distributed species inhabiting freshwater, brackish and marine environments, and especially in fishing and aquaculture species (ellis 1977; barber et al. 1981; ivanova 1983; točilina 1994; scapigliati et al. 2006; voytsytskiy et al. 2008; gruško et al. 2009; gordeev et al. 2014; izergina et al. 2014; fazio et al. 2015). data on leukocyte composition of fishes that are able to inhabit depths over 500–1500 m, perform vertical migrations and overcome strong hydrostatic and hydrodynamic resistance are quite scarce. the authors of this paper had previously studied the composition of leukocytes in the peripheral blood of the only congener of dissostichus eleginoides – the antarctic toothfish (d. mawsoni norman, 1937), which inhabits antarctic and subantarctic waters – and found resemblance with the white blood of most marine fishes (gordeev et al. 2014). other than basophils, the blood of d. mawsoni contains the same type of leukocytes as are found in freshwater species of bony fishes (ivanova 1983). patagonian toothfish (d. eleginoides) (perciformes: notothoniidea) mostly inhabit the subantarctic and northern areas of the antarctic, but are also found in the southern and south-eastern areas of the south american shelf and continental slope. the patagonian toothfish inhabits depths of up to 2000 m and is an important target species of commercial fisheries (gon & heemstra 1990). scapigliati et al. (2006) found lymphocytes, granulocytes, monocytes, erythrocytes and platelets in the tissues of the head kidney, spleen and intestinal mucosa using flow cytometry, but the leukocyte formula of the patagonian toothfish has not been known. among nototheniids there are also data on morphology of lymphomyeloid head kidney of trematomus bernacchii (boulenger, 1902) (romano et al. 2002), trematomus nicolai (boulenger, 1902) and chionodraco hamatus (lönnberg, 1905) (romano et al. 2000). haematological parameters are already in use to provide information about the health status of fish and the quality of the water in which they live (fazio et al. 2012; fazio et al. 2013). contact ilya i. gordeev gordeev_ilya@bk.ru laboratory of pacific salmons, russian federal research institute of fisheries and oceanography, 17, v. krasnoselskaya str., 107140 moscow, russia polar research, 2017 vol. 36, 1374126 https://doi.org/10.1080/17518369.2017.1374126 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0002-6650-9120 http://orcid.org/0000-0001-9086-1688 http://orcid.org/0000-0001-6931-3409 http://orcid.org/0000-0001-9052-223x http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1374126&domain=pdf material and methods fish were caught in march 2013 from the russian vessel yantar-35 in the scotia sea (atlantic sector; 53°22ʹ5 s; 50°25ʹ2 w) at a depth of 1280–1340 m using bottom longlines (mustad autoline). blood was collected from the tail vein straight after the catch. seven donor fishes were immature, not wounded, with a mean weight of 10.45 ± 2.43 kg and a mean length of 95.86 ± 8.34 cm. dissection revealed an insignificant number of parasites. a blood drop (without anticoagulants) was put on a degreased glass slide and was smeared out, dried and fixed in 96% ethanol for 30 minutes. dried-up slides were romanovsky-giemsa stained. smears were studied using biomed-6pr1-fk (x360) light microscope. two hundred white blood cells were analysed on each of the smears and the percentages of lymphocytes, neutrophils, eosinophils, monocytes and blast forms were calculated. fine photographs of cells were captured using a keyence vhx-1000 digital microscope. statistical data processing was performed using standard methods (lakin 1980). results the main cell types in the white blood of patagonian toothfish and their percentages are given in table 1. morphological investigation demonstrated that the leukocytes of d. eleginoides are the same as in other fish species (ivanova 1983; golovina & trombickij 1989). the lymphocytes were small (ø 6.1 × 5.3 µm), rounded nuclei filled most of the cell, and the cytoplasm was only a thin peripheral ring (fig. 1a). monocytes were relatively large cells (ø 13.1 × 11.7 µm) with eccentric, oval or bean-shaped nuclei. cytoplasm filled most of the cells (fig. 1b). neutrophils (ø 12.2 × 11.5 µm)were characterized by eccentric, extended or segmented nuclei. cytoplasm contained small vesicles (fig. 1c). eosinophils (ø 12.8 × 10.9 µm) had eccentric rounded nuclei and visible large vesicles in the cytoplasm (fig. 1a). blast forms were large cells (ø 11.8 × 10.0 µm) filled mostly by rounded nuclei and the remaining part comprising a thin layer of cytoplasm (fig. 1d). discussion the white blood of the patagonian toothfish is formed mainly by lymphocytes, which – of all white blood cells – play the primary part in the immune system of vertebrate animals (cooper 1980; roitt et al. 2000; galaktionov 2005; haitov et al. 2012). differing by functions, content of the membrane immunoglobulin receptors, duration of life and histogenesis, lymphocytes are heterogeneous and are divided into two main subpopulations: t-lymphocytes and b-lymphocytes (mikrjakov 1991; roitt et al. 2000; van muiswinkel & vervoorn-van der wal 2006). t-lymphocytes fulfil the functions of foreign body recognition, antigen destruction, formation of specific immunity and table 1. blood cells of patagonian toothfish. cell type percentage lymphocytes 91.6 ± 1.63% eosinophils 3.2 ± 1.24% monocytes 2.6 ± 0.5% blast forms 1.6 ± 0.4% neutrophils 1.0 ± 0.0% figure 1. blood cells of patagonian toothfish (dissostichus eleginoides): (a) lymphocyte (l), eosinophil (e); (b) monocyte (m); (c) neutrophil (n), (d) blast cell (b). scale: 10 μm. 2 i.i. gordeev et al. adaptation of fishes to parasites and toxic agents. populations of b-lymphocytes fulfil the functions of antibody synthesis, formation of precursors of antibody-forming cells and formation of memory cells (mikrjakov 1991; mikrjakov et al. 2001). the same is true in most of the perciformes (balabanova 2002). two types of granulocytes – neutrophils and eosinophils – were found among white blood cells of d. eleginoides. relative content of these cells are small. they participate in microbe phagocytosis of microorganisms, synthesis of mediators of the immune response and nonspecific factors of immunity (manning & nakanishi 1996; galaktionov 2005; havixbeck & barreda 2015; katzenback 2015). there were also insignificant portions of immature blast forms. their percentage in blood of freshwater fish species could be up to 10% (ivanova 1983). however, it should be noted that quantitative characteristics of leukocytes of all previously studied freshwater and marine fishes, in one way or another, depend on the season, habitat, feeding and other factors (ivanova 1983; golovina & trombickij 1989; točilina 1994; mikrjakov et al. 2001). compared to d. eleginoides, d. mawsoni has a lower percentage of lymphocytes and a higher percentage of eosinophils and neutrophils (gordeev et al. 2014). leukocytes of the patagonian toothfish differ from the ones of the antarctic toothfish by size. the same size ranges for lymphocytes and granulocytes were found using a flow cytometric method for two other nototheniid species: notothenia coriiceps and trematomus hansoni (scapigliati et al. 2006). the results of the study demonstrate that leucocytes in the peripheral blood of the antarctic toothfish are morpho-functionally and structurally heterogeneous: lymphocytes, monocytes, neutrophils, eosinophils and blast cells. the analysis of relative content of cell pools in the leukogram has shown that white blood of the toothfish is of lymphoid character. dissostichus eleginoides differs from d. mawsoni by having a higher content of lymphocytes and a lower content of eosinophils and neutrophils. taking into account the number of studied fish, these results are preliminary and this issue needs further study. acknowledgements the authors wish to thank dr alexei m. orlov for editing and the crew of the fv yantar-35 (orion co., ltd, khabarovsk) for their help on collecting material and transporting it from the antarctica. disclosure statement no potential conflict of interest was reported by the authors. funding the work was supported by the russian foundation for basic research grant no. 15-04-02645. orcid ilya i. gordeev http://orcid.org/0000-0002-6650-9120 daniil v. mikryakov http://orcid.org/0000-0001-90861688 lyudmila v. balabanova http://orcid.org/0000-00016931-3409 veniamin r. mikryakov http://orcid.org/0000-00019052-223x references balabanova l.v. 2002. ul`trastruktura granulocitov nekotoryh vidov okuneobraznyh ryb. (fine structure of granulocytes of some perciformes.) biologiya vnutrennih vod1, 79−84. barber d.l., westermann j.e. & white m.g. 1981. the blood cells of the antarctic icefish chaenocеphalus aceratus zönnberg: light and electron microscopic observations. journal of fish biology 19, 11−28. cooper e. 1980. sravnitelnaya immunologiya. (comparative immunology.) moscow: mir. ellis a.e. 1977. the leucocytes of fish: a review. journal of fish biology 11, 453−491. fazio f., faggio c., marafioti s., torre a., sanfilippo m. & piccione g. 2012. comparative study of haematological profile on gobius niger in two different habitat sites: faro lake and tyrrhenian sea. cahiers de biologie marine 53, 213–219. fazio f., marafioti s., torre a., sanfilippo m., panzera m. & faggio c. 2013. haematological and serum protein profiles of mugil cephalus: effect of two different habitats. ichthyological research 60, 36–42. fazio f., piccione g., arfuso f. & faggio c. 2015. peripheral blood and head kidney haematopoietic tissue response to experimental blood loss in mullet (mugil cephalus). marine biology research 11, 197–202. galaktionov v.g. 2005. evolucionnaja immunologija: učebnoe posobie. (evolutionary immunology: textbook.) moscow: ikc akademkniga. golovina n.a. & trombickij i.d. 1989. gematologija prudovyh ryb. (hematology of pond fishes.) kishinev: shtiintsa. gon o. & heemstra p.c. (eds.) 1990. fishes of the southern ocean. grahamstown: j.l.b. smith institute of ichthyology. gordeev i.i., mikryakov d.v., balabanova l.v. & mikryakov v.r. 2014. composition of leucocytes in peripheral blood of antarctic toothfish dissostichus mawsoni (nototheniidae). journal of ichthyology 54, 422–425. gruško m.p., ložničenko o.v. & fedorova n.n. 2009. gemopoėz u osetrovyh ryb. (hemogenesis of sturgeons.) astrakhan: triada. haitov r.m., ignat`eva r.m. & sidorovič i.g. 2002. immunologija. (immunology.) moscow: medicina. havixbeck j.j. & barreda d.r. 2015. neutrophil development, migration, and function in teleost fish. biology 4, 715–734. ivanova n.t. 1983. atlas kletok krovi ryb. (atlas of fish blood cells.) moscow: legkaja i piščevaja promyšlennost. polar research 3 izergina e.e., izergin i.l. & izergina l.i. 2014. atlas kletok krovi lososevyh ryb materikovogo pobereg`ja severnoj časti ohotskogo morja. (atlas of blood cells of salmons from continental coast of the northern part of okhotsk sea.) magadan: kordis. katzenback b.a. 2015. antimicrobial peptides as mediators of innate immunity in teleosts. biology 4, 607–639. lakin g. f. 1980. biometrija. (biometrics.) moscow: vysšaja škola. manning m.j. & nakanishi t. 1996. the specific immune system: cellular defenses. in g. iwata & t. nakanishi (eds.): the fish immune system: organism, pathogen and environment. pp. 160−206. london: academic press. mikrjakov v.r. 1991. zakonomernosti formirovanij a priobretennogo immuniteta u ryb. (trends of fishes acquired immunity development.) rybinsk: institute for the biology of inland waters. mikrjakov v.r. & balabanova l.v. 1979. kletočnye osnovy immuniteta u ryb. (cellular bases of fish immunity.) in n. v. butorin & v. a. flerov (eds.): fiziologija i parazitologija presnovodnyh žyvotnyh. (physiology and parasitology of freshwater animals.) pp. 57−64. leningrad: nauka. mikrjakov v.r., balabanova l.v., zabotkina e.a., lapirova t.b., popov a.v. & silkina n.i. 2001. reakcija immunnoj systemy ryb na zagrjaznenie vody toksikantami i zakislenie sredy. (reaction of fishes' immune system to water acidification and pollution by toxicants.) moscow: nauka. parish n., wrathmell a., hart s. & harris j. 1986. the leucocytes of the elasmobranch scyliorhinus vanicula l.a morphological study. journal of fish biology 28, 545−561. roitt m., brostoff j. & male d.k. (eds.) 2000. immunology. 5th edn. london: mosby. romano n., ceccariglia s., abelli l., mazzini m. & mastrolia l. 2000. lymphomyeloid organs of the antarctic fish trematomus nicolai and chionodraco hamatus (teleostei: notothenioidea): a comparative histological study. polar biology 23, 321–328. romano n., ceccariglia s., mastrolia l. & mazzini m. 2002. cytology of lymphomyeloid head kidney of antarctic fishes trematomus bernacchii (nototheniidae) and chionodraco hamatus (channicthyidae). tissue cell 34, 63–72. scapigliati g., fochetti r., tiberi m. & mazzini m. 2006. morphological and flow cytometric characterization of leukocytes from the notothenioid teleosts dissostichus eleginoides, notothenia coriiceps, and trematomus hansoni. polar biology 29, 872−877. secombes c.j. 1996. the nonspecific immune system: cellular defense. in g. iwama & t. nakanishi (eds.): the fish immune system: organism, pathogen and environment. pp. 63−105. london: academic press. točilina l.v. 1994. lejkocitarnaja formula morskih ryb. (leukocyte formula of marine fishes.) hydrobiological journal 30, 50–57. van muiswinkel w.в. & vervoorn-van der wal b. 2006. the immune system of fish. in p.t.k. woo (ed.): fish diseases and disorders. vol. 1. pp. 678−701. wallingford: cabi. voytsytskiy v.m., rodionova n.k., khyzhniak s.v. & manylo l.g. 2008. hematological characteristics of the antarctic fish. hydrobiological journal 44, 66−74. 4 i.i. gordeev et al. abstract introduction material and methods results discussion acknowledgements disclosure statement funding references notes concerning the vegetation on deflation surfaces, kapp linnk, spitsbergen jonas akerman akerman. j. 1983: notes concerning the vegetation on deflation surfaces. kapp linnc, spitsbergen. polar research i n.s., 161-169. the distribution of vascular plants within four sample areas on a deflation surface on a set of raised beach ridges near kapp linnc. spitsbergen. is described. the \,egetation cover and distribution of the different species are related to the wind pattern and microtopography. details of the distribution and growth characteristics of dryas octopetala, saxifraga oppositifolia, and silerie acaulis in relation to each other. and to the wind and microtopography are discussed. jonas i f k e r m a n , department of physical geography, university of lund. solvegatan 13, s-22362 lund. sweden; january 1983 (revised m a y 1983). the vegetation of spitsbergen shows a very great regional variability which is mainly dependent upon differences in climate, soils, hydrology, and topography. the vegetation along the strandflats of western spitsbergen is fairly uniform, however, belonging t o the ‘dryas zone’ (hinz 1976). the small-scale vegetation pattern is much more com plex than the regional, reflecting the extremely variable local conditions which may influence plant growth in the harsh periglacial environment. this paper describes the vegetation pattern on exposed deflation surfaces and its relation to the environmental factors. the study is based o n ‘sec ondary’ observations made during field work con cerning geomorphological processes (wind action, patterned ground processes, etc.); it is a brief descriptive report without any deeper analysis or discussion. the investigation area general description t h e investigation area is situated in central west ern spitsbergen in the outer part of isfjorden, east of kapp linne and isfjord radio station (78”04’n, 13”38’e) (fig. 1). to the west, the area is limited by the open sea, t o the north by isfjor den, and to the east by the starostinaksla and vardeborgaksla mountain ridges. t h e major part of the area is a wide strandflat characterized by a set of raised beach ridges u p to about 6 0 m above sea level. the area is rich in small lakes and ponds and contains several small bogs. as far as is known the area has continuous permafrost and a n active layer varying between 30 cm in the bogs to 2 rn o n the exposed beach ridges. climate isfjord radio station, which is also a meteoro logical station, lies in the investigation area. the area has a maritime influenced arctic climate with at least o n e month above *0”c, but below + 10°c. according t o the koppen classification, the sta tion has a true tundra climate (et). the mean annual air temperature is -43°c (1912-1975) and the mean annual precipitation 400.8 m m (1934-1975) (akerman 1980). t h e annual course of air temperature and precipitation is given in table 1. the wind climate is of great significance as regards the periglacial processes and the vegeta tion pattern of the area. in fig. 2 the basic wind climatic conditions are shown. for further details about the wind climate, refer to akerman (1980). site of detail studies the area in which the vegetation studies have been carried o u t is a very level set of beach ridges at a height of 20 to 4 0 m above sea level. it is about 500 x 300 m in extent and is dominated by two very level areas, o n e at a level of 22 to 24 m 162 jonas akerniati n ‘r above sea level. and one at between 32 and 38 m above sea level (figs. 3 and 4). these are deflation surfaces with a few blocks the majority of which are ventifacts showing well developed facets on their northeast exposed sides. the detail mor phology is dominated by the smooth ridge system and by polygon furrows of two different types (fig. 5 ) . the large-scale polygon pattern is the result of an ice-lvedge system with comparatively wide (0.5-1.5 m ) and deep (0.2-0.5 m) polygon furrows. the small-scale polygons are frost fissure poi! fig. 1. orientation map of the investigation area around kapp l i m e . place names and heights (in m ) according to n o r s k polarinstitutt map no. b9 blad isfiorden. scale 1 : 100.00. gons restricted to the active layer, which is here about 2 m d e e p . these furrows are generally nar rower and shallower than the large-scale pattern. the soils of the area are dominated by a fairly uniform well-washed beach gravel material in the upper 1.5-3111. below this there are thick gla ciomarine silty deposits which can be seen from the active thermokarst processes along the shores of the linnevatnet lake and the linneelva river. the beach gravel. lacking finer fractions, is well-drained and dry and lacks larger amounts of ground ice i n winter. t u h k i \ i c m rnonrhl! a i r lcmpcrdture ( l y j 6 1 y 7 5 ) and mean monthly precipitation (19361975) at isfjord radlo station. kapp l i n n e . spitshcrgcn j f m a m j j 4 s 0 n d t e m p ( ” ( ‘ ) 1 1 7 1 1 5 1 7 . 2 9 . 2 -3.5 + 1 . 6 +4.7 t 4 . 2 t 1 . l -3.4 -7.1 -9.5 prcc ( r n m ) ? i 5 30 i 30.9 22.3 23.6 24.8 35.8 45.0 40.6 41.3 38.8 35.6 l-/ february i 1 july fig. 2. monthly percentage frequencies (frequency interval 1 % . black areas represent more than 5 % ) of concurrent wind forces (beaufort scale) and wind directions at kapp l i d (isfjord radio) during the period 1956 to 1975. vegetation on deflation surfaces 163 vegetation characteristics general distribution the study area lacks a continuous vegetation cover and the vegetation and occurrence of iso lated plants are dictated by the niicrotopography. the regulating factors are the wind and the soil moisture content. t h e general distribution of the vegetation is shown in fig. 6. in this figure three classes are distinguished: (1) the thermokarst sur faces, (2) the deflation surfaces, and (3) the shal low depressions. the tlierrnokarst surfaces are generally very poor in vegetation as they are subject to intensive disturbances like earth flows, slumps and rill erosion. some areas which are temporarily more stable have mosses. lichens, and some vascular plants saxifraga sp., ranunculus sp., draba sp., etc. the deflation surfoces constitute the flattest in the area and the crests of the raised beach ridges. these surfaces appear very poor in vegetation, but the number of lichens and mosses is great and the area studied has a fairly large number of wind eroded tufts of dryas octopetala and silene acaic [is. saxifraga oppositifolia, draba n i d i s , and fig. 3. topographic map of the investigation area. the test sur faces are shown by squares (a-d). contour interval 2 r n . 6 0 . 20 10 stellaria crassipes are also fairly common at pro tected 'microsites' o n these surfaces. t h e polygon furrows o n the deflation surfaces are also rich in mosses and salix polaris (fig. 7 ) . the depressions between the smooth ridges (incl. the polygon furrows) have a protective snow cover during winter. also providing moisture to the soil in the early summer. and have a discon tinuous vegetation cover dominated by lichens and mosses; the surfaces are comparatively rich in plants. the dominating vascular plants are salix polaris. saxifraga oppositifolia, stellaria crassipes, silene acaulis, draba alpina, and poa alpina. llnne elva the deflation surfaces t h e deflation surfaces are characterized by the sandy-gravelly material and by a pavement of small stones and pebbles 1-3 cm in diameter (fig. 8); vegetation coverage is not great. including the lichens and mosses the percentage of vegetation cover is larger than the general impression may indicate. however. in order to obtain a more representative picture of the vegetation distri bution, the deflation surfaces were studied in detail within four test surfaces 7 x 4 m large (fig. 3 ) . these surfaces were photographed from a fig. 5 . air photograph of the investigation area. detail from sorsk polarinstitutt airphoto no. s69 2436. vegetation on deflation surfaces 165 fig 6 vegetation character istics of the investigation area 1 ‘the thermokarst surfaces’, 2 ‘the deflation surfaces’, and 3 ‘the depressions’ 1 o o u height of 6 m , affording the possibility of obtain ing the percentage coverage of the vegetation within each 7 x 4 m sample area. within these surfaces a 1 x l m frame subdivided into an 0.1 x 0.1 m grid (fig. 7) was used for evaluating the detailed distribution of the vegetation and the number of plants per unit area. t h e most characteristic plant of these surfaces is the dryas octopetala, which grows in wind eroded tufts evenly distributed over the area. the tufts a r e very characteristically parabolic in shape (figs, 9 and l l ) , indicating the active wind direc tion from the northeast (akerman 1980). t h e percentage coverage of dryas on the deflation surfaces is 19.4% (table 2 ) ; the distri bution arrangement within the sample areas is shown in fig. 10a-d. the parabolic-shaped dryas tufts have a very characteristic form which fig. 7. the characteristic veg etation pattern in the polygon furrows. the frame is 1 x 1 m. 166 jonas a k e r m a n has been mapped by stereographic methods based on vertical photographs taken from a height of 2 rn. a n example is given in fig. 11, saxifraga opposirifolia, which is one of the most common and characteristic plants of spitsbergen, is also found o n these deflation surfaces, but here this plant is apparently growing at the very limit of existence. elsewhere s. opposirifolia is found evenly distributed over almost all suitable sur faces, but here almost exclusively in association with the dryas tufts. o n these exposed surfaces s. oppositifolia is obviously entirely dependent upon the protection that the dryas tufts a r e providing. t h e position of the s . oppositifolia plants within the four test surfaces in association with the dryus tufts was investigated (fig. 12 and table 3). in this investigation six ‘classes’ were distinguished ( a = not in direct contact with the dryas tufts, b = central lee position, c = marginal lee pos ition, d = central windward position, e = mar ginal windward position, a n d f = ‘inside’ the dryas tufts. t h e distrbution frequence is given in table 3. it is clearly indicated in this table that s. opposirifolia is dependent upon the dryas for its existence 92.3% of all plants o n t h e deflation the dryas tufts may provide a higher s o i l mois ture content, a higher content of fines, and above fig. 8. the parabolic shaped wind-eroded tufts of d q s a ocf0. surfaces are found in ‘ontact with the dryas tufts’ perdu on the deflation surfaces. the active uind direction i s indicated by the g u n . fig. 9. detail of one perfectly developed parabolic d ~ y a s tuft on the deflation surface. vegetation on deflation surfaces 167 flg. 10. the distribution of dryas octopetala within the four test surfaces based on photo graphs taken from a height of 6 m above each surface > o c m fig. 11. the ’topography’ of one of the parabolic-shaped drvas tufts on the deflation surface (test surface b) based on ster eographic measurements in vertical photographs taken from a height of 2 m. contour interval 2 cm. all protection from the desiccating and abrasive effects of the strong winds, as the high percentage of observations within the ‘lee position class’ (73%) indicates. another plant which is interesting in relation to wind activity within the area is silene acaulis. this plant is not very common on the deflation surfaces but occurs in sufficiently large numbers to be used for a simple analysis (table 4). a a a b e a ld a fig. 12. the division used in the investigation of the position of saxifraga oppositifolia in relation to the dryas octopetala tufts. a . not in contact with the dryas tufts, b . central lee position, c. marginal lee position, d . central windward pos ition, e . marginal windward position, and f. inside the dryas tufts. many of the silene tufts have wind scars on their northeast exposed side (43.6% of the obser vations) and a clear correlation between the size of the tufts and the wind erosion was observed early. t h e tufts with a diameter below locm table 2. percentage vegetation cover on the four sample areas based on the total area 7 x 4 m (dryas) and five 1 x 1 m test squares (mosses and lichens). a b c d mean dryas octopetala 17.9% 20.4‘+ 22.5% 16.7% ly.4% mosses and lichens 26.6% 19.2% 20,270 28.2% 23.5% total 44.5% 39 6% 22.7% 44 9% 3 7 . 9 4 168 jonas akerman table 3 the distribution frequence of saxifraga opposilifofia in relation to tufts of dryas ocfopctala within four test surfaces on a deflation surface east of kapp linnt. spitsbergen. a b c d mean a . not in contact with dryas 8.4 8 1 7.9 6.3 7.7% b. central lee position 47.4 44.2 50.3 42.9 46.2% c. marginal lee position 29.5 28.8 22.7 26.1 26.8% d. central windward position 4.2 7.2 5.6 9.3 6.6% e . marginal windward position 2.1 4.5 1.9 3.9 2.7% f. inside the d r y s tufts 8.4 7 2 17.2 11.5 11 .o% number of plants ( 7 x 1 m) 95 111 87 105 99.5 table 4. observations on the relation between wind erosion and the size of tufts of silene a c a u l b within the four test surfaces on deflarion surfaces east of kapp linne. spitsbergen. a b c d mean ~~ number of tufts (4 x 7 m) intact wind eroded intact < locm intact > locm wind eroded < 10 cm wind eroded > 10 cm 39 45 22 41 35.7 5 3 . 8 7 ~ 5 1 . 1 9 59.3% 61.2% 56.470 46.2% 48.9% 40.7% 38.870 43.6% 48.7% 444% 49.2% 51,770 48.5% 5 . 2 4 6.7% 10.1% 9.5% 7.9% 7 . 7 4 13.3’3 9.3% 8.6% 9.7% 3 8 . 5 8 35.6cc 3 1 . 4 7 ~ 30.2% 33.970 ‘ t 10. height 9 8 . 1 . diameter 0 f i g . 13 the relation between tuft height and tuft diameter of silene a c a u l b l. at the deflation surfaces, kapp linnt. spitsbergen. ,i 5 10 15 20 25 r25 cm showed erosion in only 7 . 7 % of the observed cases. while tufts with a diameter above locm were wind eroded in 38.5% of the observed cases (table 4). as there is a clear correlation between the tuft diameter and the height of the tufts (fig. 13), it is indicated that 3-4 cm height is the critical tuft height for silene acaulis in this environment. conclusions the distribution of vegetation on the exposed parts of the deflation surfaces shows a character istic pattern governed by the direct or indirect action of the wind. the microtopography down to the centimetre scale is one of the most impor tant factors. the dominating vascular plant on the most exposed surfaces is the dryas octopetala l., which may cover up to 22.5% of the surface. on these surfaces the growth pattern is charac terized by wind-eroded parabolic-shaped tufts fairly evenly distributed over the surface. saxifraga oppositifolia l. is the second plant occurring in any quantity and in this environment is apparently entirely dependent upon the pro tection provided by the dryas tufts. the majority of the s. oppositifolia l. plants found are located in the lee and with direct contact with these tufts. silene acaulis, which grows in more or less circular tufts, is commonly subject to wind erosion. of all observed tufts, 43.6% showed scars of wind erosion. the critical tuft height is about 3-4cm and of tufts higher than 3-4cm, only 7.9% was not eroded by the wind. vegetation on deflation surfaces 169 references akerman. h . j. 1980: studies on periglacial geomorphology in west spitsbergen. meddelande f r d n lunds uniueristets geo grafska institution ser. auh. l x x x i x . 297p. gill, d. 1972: the point bar environment in the mackenzie river delta, can. j. earth sci. 9 ( i l ) , 1382-1393. hinz, w. 1976: z u r okologie der tundra zentralspitzbergens. norsk polarinstituff skrifter n r . 163. peterson. k . m . & billings, w. d. 1980: tundra vegetational patterns and succession in relation to microtopography near atkasook, alaska. arctic and alpine research 12 ( 4 ) , 473 482. raup, h . m. 1971: the vegetation of the mesters wig district, northeast greenland. meddelelser om grlinland. 194 ( 3 ) . ronning, 0. 1. 1979: svalbards flora. norsk polarinstirutt polarhbndbok nr. 1 . scholander, p. f . 1934: vascular plants from northern sval bard. skrifter om sualbard og ishaoet n r . 62. theakstone, w . h . & knighton, a . d. 1979: the moss aongs troemia longipes, an environmentally sensitive colonizer of sediments at austerdalisen, norway. arctic and alpine res. 11 ( 3 ) . 353-356. seabird distribution in the northern barents sea marginal ice-zone during late summer fridtjof mehlum mehlum, f. 1990: seabird distribution in the northern barents sea marginal ice-zone during late summer. polar research 8 , 61-65. the abundance of five seabird species in ice-covered parts of the northern barents sea in late summer 1982 was analysed in relation to differences i n sea-ice coverage. the dominant species was the little auk ane alle. differences between the seabird species in the use of the sea-ice habitat are partly explained by differences in their feeding ecology, and, for alcid species, by the need for open water for getting airborne. all species, except for the fulmar fulmarus glacialis, took as part of their diet organisms associated with the subsurface of the sea-ice. the little auk fed mainly on large copepods and pelagic amphipods, and was observed mainly in areas with low ice-cover where such zooplankters are abundant. fridtjof m e h b m , norsk polarinstifutt, p. 0. box 158, n-1330 oslo lufthaun, norway; september 1989 (revised february 1990). the marginal ice-zones in arctic and antarctic waters are generally thought to be important to seabirds (brown 1989). the pelagic distribution patterns of several species, e.g. the ivory gull pagophila eburnea and ross' gull rhodostethia rosea in the northern hemipshere (mehlum 1989), and snow petrel pagodroma niuea, emperor penguin aptenodytes forsteri, and adelie penguin pygoscelis adeliae in the southern hemisphere (cline et al. 1969; ainley et al. 1984), are limited by the extent of the sea-ice. other species occur in high densities along ice-edges and in the marginal ice-zone (irving et al. 1970; divoky 1979; renaud et al. 1982; brown 1985; fraser & ainley 1986). however, few studies have conclusively demonstrated that the occurrence of seabirds in sea-ice is a direct result of searching for prey, or of physical features (fronts, convergences, etc.) which may coincide with concentrations of prey (fraser & ainley 1986; hunt this volume). in summer, in the northern barents sea, the ice-edge and the marginal ice-zone retreat north wards (vinje 1985). a high biological production is associated with the ice-zone during this retreat (sakshaug & skjoldal 1989), and provides food for the large number of seabirds (mehlum 1989). different seabird species in this area prey upon different food types according to their mor phological limitations. some are surface feeders, while others are pursuit divers which hunt their prey in the free water masses or at the under surface of the sea-ice. sea-ice will naturally limit the access t o the sea for foraging seabirds, especially for surface feeders. because planktonic organisms are patchily distributed at scales of metres to hundred of metres (haury et al. 1978), it is likely that the distribution of the different seabirds at sea and within the sea-ice zone will reflect the availability of suitable prey. in this paper 1 present seabird abundances in different concentrations of sea-ice east of svalbard, and discuss the results in relation t o the feeding eco logy of the birds. material and methods the survey was made from r/v 'lance' 22-25 august 1982 in the marginal ice-zone between kong karls land and frans josef land. i made 122 10-minute counts between 79" 17'n, 40"24'e and 79"00'n, 31" 14'e. ice-cover was recorded and averaged over each 10-minute period on a scale from o / 8 (no ice) to 8/8 (100% ice-cover). data from 1-2, 3-4, 5-6, and 7-818 were pooled in order to increase the sample size in each category. no 10-minute periods had 018 ice-cover. seabird counts were made by recording all birds observed by the naked eye within 180 degrees i n front of the vessel when moving at >5 knots (mehlum 1989). the survey occurred after the breeding season, so as not to bias the results by foraging distance 62 f. m e h l u m limitations of birds associated with breeding col onies. some seabirds were collected for stomach con tent analyses. the procedure and complete results were reported in mehlum & gjertz (1984). results the most commonly seen species was the little auk alle alle, which accounted for 63.4% of the birds observed (table 1); the black guillemot cepphus grylle was the second most numerous species. only 17 briinnich’s guillemots uria lom uia, one of the most numerous species in the northern barents sea seabird community (mehlum 1989), were seen. twenty-one ross’ 50 40 30 20 10 table i . total number of individuals observed among the seven most numerous seabird species between kong karls land and frans josef land, august 1982. median ice-cover for the obser vations of each species i s also presented. ~~ species number % median ice-cover little auk black guillemot kittiwake fulmar lvory gull ross’ gull briinnich‘s guillcmot alle ulle 4,360 63.4 318 rissa triductyla 736 10.7 418 pagophila ehurnea 196 2.8 418 rhodostethiu rosea 2 i 0 . 3 418 cepphus grylle 1,154 16.8 218 fulmarus glacialis 395 5.7 318 uriu lomoiu 17 0.2 318 0 1-2 3-4 5-6 7-8 (25.4%) (41.9%) (23.0%) (9.8%) ice-cover fig. 1 . rclative abundances of five seabird species in relation to ice-cover. the y-axis represents the percentages of the 122 10 minute observation periods within which the species were present. the percentages of the total transect length in each ice-cover category are given in parentheses on the x-axis. seabird distribution in the northern barents sea 63 t t occurred more frequently in areas with dense ice cover (7/8-8/8) (x2 = 96.0, df = 1, p < 0.001). ross' gulls were seen in ice-cover from 3/8 to 7/ 8, and 57% of the observations were made in 3/ h / 8 . the sample size is too small to determine preferences of ice coverage. in fig. 2. the abundance of little auks along the transect is compared to the salinity profile (gammelsr0d unpublished) and the density of calanoid copepods sampled below the sea-ice sub surface (gulliksen 1984). in the eastern part of the section, there was a strong salinity and tem perature stratification above 20-25 m, with low salinities and temperatures near the surface. all the under-ice zooplankton stations within the no copepodslm' 1 161 68 132 45 7 2 t ' $ t no. llllle auksi10 mln\ 10.6 1 45.7 i 57.0 1 53.0 b 1 i ' , i t ' " ' " ' ' i ' i d id0 200 5m section: s a l i n i t y [ p s s 181 t l m e : 8 2 . 8.2(: 8.45 82. 8.25:23.29 pos: 78.82on 2 1 . 5 o 0 e 1 9 . 5 1 ' y 42.58oe o l s t ikml: fig. 2. salinity profile for the section investigated. mean num bers of little auks a l l e alle observed per 10-min observation period and dcnsity per mz of copepods below the sea-ice are also given. (salinity profile, after t. g a n i m e l s r ~ d unpublished; copepods, after gulliksen 1984.) gulls were seen. this species was recorded in 9 of the 122 10-minute periods. both the little auk and the black guillemot were less frequent in dense ice cover (7/8-8/8) than in areas with more open water (x2 = 348.2, df = 1, p<o.ool and x 2 = 117.8, d f = 1, p < 0.001, respectively) (fig. 1). the fulmar ful marus glacialis and the ivory gull were more evenly distributed over the four groups of ice coverage. in contrast, kittiwakes rissa triductylu eastern part of the section contained high num bers of calanoid copepods, while one station to the west had few (gulliksen 1984). the data presented in fig. 2 indicate that areas with abun dance of zooplankton associated with the strong stratification in the upper layer of the sea are attractive feeding areas for little auks. a separate analysis of the stomach contents of birds shot during the cruise (summarized in table 2) showed that the marginal ice-zone was used extensively as a feeding area (mehlum & gjertz 1984). most individuals contained newly ingested prey. sympagic fauna (i.e. animals associated with the undersurface of the sea-ice) were major prey of black guillemots, kittiwakes and ivory gulls (table 2 ) . however, little auks and fulmars mainly preyed upon pelagic organisms. sympagic organisms, mainly gammarid amphipods and polar cod boreogadus saida, were found in stomachs of all the seabird species investigated, except for the fulmar. only four fulmar stomachs were examined, and they contained remnants of 7able 2. stomach content of seabirds collected in the marginal ice-zone between kong karls land and frans josef land, august 1982. sample sizes in parentheses (data from mchlum & gjertz 1984). nereis culanus gammaridae parathemisto 3. saidu others f. glacialis (4) xx xx xx * a . a l k (19) xx x xx c. g y l l e (7) x x xx x** r. tridactyla (7) xxx xx*** p. eburnea (6) x xx x**** x = 10-40%, xx = 40-70%, xxx = >70% frequency of occurrence in stomachs investigated. * * l y c o d e s * * * l y c o d e s , cottidac * * * * mammalian blubber cephalopods 64 f. m e h l u m pelagic prey, i.e. polychaetes (nereis sp.), cepha lopods (gonatus sp.), and the pelagic amphipod parathemisto libellula. the main diet of little auks was copepods calanus sp. and parathem isto. in the northern barents sea the fauna of sympagic animals is well developed, reaching a mean biomass of 9.6 g per m2 sub-surface of sea ice, with higher values in multi-year ice than in first year ice (gulliksen 1984; gulliksen & l0nne 1989). discussion in late august 1982, there were large numbers of little auks in the marginal ice-zone in the area between the eastern parts of svalbard (kong karls land) and frans josef land. according to the distribution maps presented by mehlum (1989), this is probably a regular phenomenon. the area is also important for other seabird species, but they are less common than the little auk. species such as the ivory gull, ross’ gull and black guillemot are often associated with areas with sea-ice in the northern barents sea during late summer, while others such as the fulmar and the kittiwake are distributed both in ice-covered and open waters farther south at this time of the year (mehlum 1989). a high pro portion of the little auks and black guillemots are immature and moulting individuals (mehlum 1989). the less frequent occurrence of little auks and black guillemots in very dense sea-ice (7/8-8/8) may partly be due to their need for sufficient open water between the ice-floes to take off into the air. gulls, on the other hand, which can take off vertically, are associated with dense ice where they search for prey which may be exposed when ice-floes grind together in the moving pack-ice or when they turn upside down. the polar cod was a major prey of kittiwakes, ivory gulls and black guillemots. the youngest year-groups of polar cod are known to associate with sea-ice, the typical habitats being between sandwiched ice-floes or in melting holes and crev ices in the ice ( l ~ n n e & gulliksen 1989). in contrast, the little auk does not seem to be dependent on the sympagic fauna, but feeds mainly on copepods and young specimens of the amphipod parathemisto libellula living in the water column. bradstreet (1982) also reported that little auks selected the oldest age-stages of the largest potential prey in his study area in the canadian arctic. similar information is reported from novaya zemlya (zelickman & golovkin 1972). the strong stratification in temperature and salinity observed above 20-25 m depth along the ice-edge was caused by melting of sea-ice, forming a relatively stable and nutrient rich body of water in which primary production is high (sakshaug & skjoldal 1989). the algal populations are grazed upon by the growing stages of zooplankton, i n these waters dominated by calanus glacialis. according to sakshaug & skjoldal’s (1989) model of the abundance of calanus glacialis along the ice-edge in the northern barents sea, the largest (oldest) age-stages should be found in the outer part of the ice-zone, grazing on the phytoplankton bloom. it was in these areas with low ice-cover that we also found the highest density of little auks. in other geographical areas, large concen trations of the little auk have been reported in association with sea-ice, continental slopes and at different oceanic ‘fronts’ (bradstreet & brown 1985), where they feed upon the prey that tend to accumulate there in high densities (pingree et al. 1974; bradstreet 1980, 1982; brown 1980; bradstreet et al. 1981). bradstreet & brown (1985) showed how densities of little auks and zooplankton above 20 m increase towards the outer edge of the southern scotian shelf, while zelickman & golovkin (1982) reported that 75% of the little auks off novaya zemlya were for aging in areas with dense swarms of crustaceans. acknowledgemenfs. i am indebted to bjmn linnehol, viggo ree and ragnar syvertsen for their assistance in the regis trations of seabirds, and to tor gammelsr@d for the permission to use his unpublished oceanographical data. references ainley, d. g., o’connor, e. f. & boekelheide, r . j . 1984: the marine ecology of birds in the ross sea, antarctica. ornithol. monogr. 32. bradstreet, m. s . w . , 1980: thick-billed murres and black guillemots i n the barrow strait area, n.w.t., during spring: diets and food availability along ice edges. cun. j . zool. 58, 2 12&2 140. bradstreet, m . s. w. 1982: pclagic feeding ecology of dovekies alle alle in lancaster sound and western baffin bay. arctic 35, 126140. bradstreet, m. s . w . &brown, r. g. b. 1985: feeding ecology seabird distribution in the northern barents seu 65 of the atlantic alcidae. pp. 264-318 in nettleship, d. n. & birkhead. t. r. (eds.): theatlanticalcidae. academic press. bradstreet, m. s . w., nettleship, d . n . , roby, d . d. & brink, k . l. 1981: diet of dovekie alle d i e chicks in north-west greenland. can. wildl. seru. 'studies on northern seabirds' manuscript reporf 98, 1-31. brown, r. g. b. 1980: seabirds as marine animals. pp. 1-39 in burger, j . , olla, b. & winn, h. e. (eds.): behavior of marine animals 4. marine birds. plenum press, new york. brown, r. g . b. 1985: the influence of ice on the ecology of arctic and antarctic seabirds. proc. xviii int. o m . congr., ssy-566. brown, r. g . b. 1989: seabirds and the arctic marine environ ment. pp. 179-200 in rey, l. & alexander, v. (eds.): pro ceedings of the sixth conference of the comitk arctique international, 13-15 may 1985. brill, leiden. cline, d. r., siniff, 0. b. & erickson, a . w. 1969: summer birds of the pack ice in the weddell sea, antarctica. auk 86, 701-71 6. divoky, g . j . 1979: sea ice as a factor in seabird distribution and ecology in the beaufort, chukchi, and bering seas. wildl. res. rep. 11, u . s . fish and wildl. seru., %17. frascr, w . r . & ainley, d . g . 1986: ice edges and seabird occurrence in antarctica. bioscience 3 6 , 2 s w 6 3 . gulliksen, b. 1984: under-ice fauna from svalbard waters. sarsia 69, 17-23. gulliksen, b. & l ~ n n e , 0. j. 1989: distribution, abundance, and ecological importance of marine sympagic fauna in the arctic. rapp. p.-u. keun. cons. lnt. explor. mer 188, 1 3 3 13% haury, l. r . , mcgowan, j . a . & wiebe, p. h . 1978: patterns and processes in thc time-space scales of plankton distri butions. pp. 277-327 in steele, j . h . (ed.): spatial patterns in plankton communities. plenum press, new york. irving, l . , mcroy, c. p. & burns, j . j. 1970: birds observed during a cruise in the ice-covered bering sea in march 1968. condor 72, 110-112. l0nne, 0. j . & gulliksen, b. 1989: size, age and diet of polar cod, boreogadus saida (lepechin 1773), in ice covered waters. polar b i d . 9, 187-191. hunt, g . l., j r . 1990: the pelagic distribution of marine birds in a heterogeneous environmcnt. polar res. 8, 4>54. mehlum, f. 1989: summcr distribution of seabirds in northern greenland and barents seas. nor. polarinst. skr. 191.56 pp. mehlum, f. & gjertz, 1. 1984: fccding ecology of scabirds in the svalbard area a preliminary rcport. nor. polarinst. rupp. 16. pingree, r. d . , forster, g . r. & harrison, g. k. 1974: tur bulent convergent tidal fronts. j . mar. biol. assoc. u k 54, 469-479. renaud, w. e., mclaren, p . l. & johnson, s . r. 1982: the dovekie ane a l k as a spring migrant in eastern lancaster sound and western baffin bay. arctic 35, 118-125. sakshaug, e . & skjoldal, h . r. 1989: lifc at the icc edge. ambio 18, 6g67. vinje, t. 1985: drift, composition, morphology and distribution of the sea ice fields in the barents sea. nor. polarinst. skr. 179c, 26 pp. zelickman, e. a . & golovkin, a. n. 1972: composition, struc ture and productivity of neritic plankton communities near bird colonies on the northern shore of novaya zemlya. mar. biol. (berlin) 17, 265-274. ocean surface temperatureand colour studies from satellites jan-pe‘iter pedersen pedersen, j.-p. 1990: ocean surface temperatureand colour studies from satellites. polar research 8, 5 9. this paper introduces satellitc remote sensing of sca-wrface temperatures and ocean colour studies. the basic radiative transfer cquations and available satellite sensor systems are presented. the final part of the paper focuses on tcmpcraturc applications. sea surface temperature data derived from availahle satellite data are presented and discussed. jan-perter pedersen. department of information technology, foundation of a p p l i e d research at the unioersity o f tromsm ( f o r u t ) , p . 0. box 2806 elurrh@y. n-9001 trontsm, n o r w a y ; february 1989 (revised june 1989) the role of satellites in the monitoring of con ditions of the earth’s atmosphere and surface is becoming increasingly important. satellite measurements are particularly useful in disci plines such as oceanography and meteorology/ climatology. due to the frequent and the sim ultaneous large area coverage, vast areas of ocean and atmosphere can be studied simultaneously. oceanographic applications of satellite remote sensing mainly include studies of surface para meters such as: temperatures, currents, winds and waves. also of interest are studies of ocean colour which is an index of (near) sub-surface parameters such as ocean productivity and/or concentrations of suspended material. the application areas of a remote sensor are mainly determined from the operational charac teristics of the sensor. the remote sensing of ocean colour requires that the sensor can detect the radiation coming from below the ocean surface. this radiation carries information about sub-surface chemical and/or physical conditions. such radiation is present in narrow spectral bands in the blue and the blue-green part of the elec tromagnetic spectrum (swain & davis 1978). it is therefore a requirement that an ocean colour observing sensor must operate narrow spectral bands in the blue/blue-green part of the spectrum. the surface temperature determines the ther mal infrared radiation emitted from the sea. the radiation is emitted according to planck’s radi ation law (swain & davis 1978). the surface temperature is observable by a remote sensor operating in the thermal infrared, o r in the micro wave part of the electromagnetic spectrum. application of traditional oceanographic methods in combination with satellite remote sensing has proved a high degree of correlation between the observed sea surface temperature and the near sub-surface productivity. the areas of highest productivity normally correspond to the areas of lowest surface temperatures (nasa 1984b). regions of strong tidal mixing and upwell ing of deeper water appear as local cool areas exposing different temperature gradient patterns. the temperature gradients (fronts) reflect the physical processes (currents and mixing) which affect the local biological productivity. ocean colour information derived from spaceborne data has been used by fishermen off the coast of cali fornia as a tool for increasing the tuna catches (nasa 1 9 8 4 ~ ) . in addition to fish stocks, areas of enhanced productivity have been observed as feeding areas for marine birds and other predators (schneider this volume). radiative transfer equations the radiance detected by a remote sensor is com prised of different components, originating from different parts of the total sensor-atmosphere ocean system: the radiance originating from the atmosphere t h e radiance reflected at the ocean surface the radiance originating from and below the the individual component contribution to the (atmospheric) (reflected) surface (emitted) 4 jan-petter pedersen n 025 i j amos m c 0.9 3 e m m fig, 1. components of the total signal detected by a remote sensor in the visible and in the thermal infrared wavelength regions. the numbers indicate the relative fractional con tribution limits for the different components (maul 1981). total signal is strongly wavelength dependent. fig. 1 illustrates schematically the fractional com ponent contribution to the total signal at the visible and the thermal infrared wavelength regions. the numbers indicate the relative frac tional contribution limits for the different com ponents. the figure shows that in the visible region the atmospheric component of the total detected signal will comprise 6@90%. when deal ing with quantitative remote sensing of ocean near-surface conditions, the interesting com ponent is that representing the near-surface emission. this means that the components repre senting the atmospheric contribution and the sur face reflection have to be quantified and compensated for. the equation of radiative transfer the electromagnetic radiative transfer in a sensor atmosphere-ocean system can be described math ematically by the equation of radiative transfer. this equation describes all effects inherent upon the electromagnetic radiation. of special import ance are the effects of the atmosphere (attenu ation) between the sensor and the measured surface. the atmospheric attenuation depends on the wavelength of the electromagnetic radiation and the composition of the atmosphere along the sensor's line of sight. the complete form of the equation of radiative transfer is complicated (liou 1980), and only a simplified component version of the equation is presented here (pedersen 1987): + re@, h, $91 + r,(a, h, p, cp) (1) where r(a, h, p, cp) = the radiance detected by a sen sor at altitude h, at a given wave length a, in the direction (p = cos-'o, 4). 8, $j represent the zenith and azimuth angles, respectively. rr(a, h, p, cp) = the radiance component due to reflection of solar radiation at the surface. re(& h, p, cp) = the radiance emitted from the surface. rp(h, h, p, cp) = the atmospheric radiance (emitted and reflected). $a, h, p, cp) = the atmospheric attenuation of the surface radiance. solving equation (1) implies applications of proper boundary conditions at the top of the atmosphere, at the atmosphere-ocean interface and at the sea bottom (if visible) (guzzi et al. 1987). in practice this means that the equation is almost impossible t o solve without any sim plifications. the simplifications of the complete equation are strongly dependent upon the actual wave length bands applied. for example, fig. 1 shows that a quantitative application of the emitted radi ance component in the visible region requires that the dominating atmospheric component must be determined and corrected for (pedersen 1987). in this region the surface reflection will also con tribute significantly. a similar application in the thermal infrared region means that the reflected component can be ignored without introducing any significant errors (cf. fig. 1). the atmospheric component is also less dominating in this region. compared to the visible region, the atmospheric contribution is more easily determined in the thermal infrared region (pedersen 1982, 1987). the quantitative expressions are outside the scope of this paper. available satellite sensors the noaa-series of polar orbiting, sunsynch ronous satellites from which data are read out at ocean surface temperatureand colour studies from satellites 5 tromsg satellite station (tss), offer the oppor tunity t o study surface phenomena in arctic regions with a high frequency of repetition. the primary sensor of the noaa satellites is the advanced very high resolution radiometer (avhrr) observing in the visible and in the thermal infrared region. the thermal infrared data from the noaa satellites are frequently used for studying currentsand the sea surface temperatures (sst). the spatial resolution of the noaa-data of 1 km limits their application to open ocean areas. the new generation of satellites represented by the landsat/thematic mapper (tm) offers, however, the opportunity t o study surface phenomena at an increased spatial reso lution. compared to the noaa satellites, the 120 meter resolution of the tm thermal channel is more adaptable for coastal-zone applications. the important operating characteristics for the satellites are presented in table 1. the landsat satellites also operate another visible/near-infra red radiometer, the multispectral scanner (mss). due t o the spectral location and bandwidth of the mss bands, this radiometer is not suitable for quantitative ocean colour applications. until now, there has been only one operational satellite dedicated to ocean colour studies. this satellite, nimbus-7, was launched in 1978, and was operational for about five years. the ocean colour sensor on board nimbus-7 was a passive radiometer, czcs (coastal zone colour scanner), operating at narrow visible and near infrared spectral bands (see table 1). the spatial resolution of the sensor was 800 meters, which again limits the applications mainly to open oceans. sensors analogue to the czcs are plan ned to be put on future earth observation plat forms. these sensors will, however, not become operational until the mid-1990s. geophysical satellite data applications ocean colour studies during its operational lifetime, data from nimbus/czcs were applied for a number of ocean colour studies (gordon & clark 1980; sturm 1982; gordon et al. 1983). czcs data have, however, not been applied for quantitative ocean colour studies in norway. a study presented by gordon et al. (1983) discussed the application of czcs data for the determination of phytoplankton pigment con centrations in the middle atlantic bight off the east coast of the usa and in the sargasso sea. the pigment' concentrations determined from sat ellite images were compared to measurements performed by ships. the results obtained sug gested that over the 0.08-1.5 mg/m3 range, the error in the retrieved pigment (mainly chloro phyll a) concentration is of the order 3 0 4 0 % for a variety of atmospheric conditions. fig. 2 shows a comparison of ship and czcs measured pigment concentrations (gordon et al. 1983). the main problem in ocean colour studies is t o obtain a correct atmospheric correction. the atmosphere is a strongly varying medium both in time and space, and these variations are hardly described by any given law. the variations must therefore rely on observations. there exists no table i . actual ocean colour/temperature observing satellites operational characteristics. avhrr tm czcs spectral bands (p) spatial resolution swath width operational status 0.58-0.68 0.7cl1.1 3.55-3.93 10.3-11.3 11.5-12.5 l x l k m c. 2,500 km active 0.45-0.52 0.5>0.m) 0.6w.69 0.764.90 1.55-1.75 2.08-2.35 10.412.5 30 x 30m 120 x 120m thermal ir 185 km active 0.4n.45 0.51-0.53 0.54-0.56 0.660.68 0.704.80 10.5&12.50 0.8 x 0.8 km c. 2,500 km passive 6 jan-petter pedersen -2 -i i 2 log (ship pigmento) fig. 2. comparisons of ship and czcs measured pigment concentrations for four different nimbus orbits (3157, 3171, 3240, 3351) (gordon et al. 1983). developed observation network in ocean areas, and present satellite sensors do not give the radio metric accuracy necessary for operational atmospheric corrections of high quality. sea-surface temperature studies the thermal channels of the avhrr and the tm are t o be considered for this application. the avhrr 10.3-11.3 pm, the 11.5-12.5 pm chan nels, and the tm 10.4-12.5 pm channel are all in the same part of the electromagnetic spectrum. notice, however, that the spectral width of the tm channel is twice that of the avhrr channels. due to the spectral coincidence of the tm and avhrr channels, they are applicable for comparable studies of sea surface tempera tures. according to the pre-launch specifications, the temperature sensitivities are <0.12 k and 0.5 k at a surface temperature of 300 k for the avhrr and tm, respectively (nasa 1984a; schwalb 1979). the most significant difference between the channels is their spatial resolution, 120 meters for tm compared to 1 km for avhrr. the spatial resolution of the avhrr limits its applications primarily to open oceans. for studies in the coastal zone and within the fjords, the tm ther mal channel is the most suitable. different algorithms have been proposed for retrieval of sea surface temperatures (sst) from thermal infrared satellite data. these algorithms range from physical solutions of the equation of radiative transfer to algorithms based completely upon statistical regression analysis. the absolute accuracies, as compared to in situ data, vary from approximately 1 deg. kelvin for the single band direct solution algorithm to a few tenths of a kelvin for the split-window algorithms (pedersen 1982). weinreb & hill (1980) describe an algorithm applying single band thermal infrared data. from the general equation of radiative transfer in an attenuating medium (cf. equation l ) , the absolute surface temperature is derived after having cor rected for the atmospheric influence. the atmospheric correction is calculated from an input of atmospheric temperatureand humidity pro files. this algorithm has been implemented for operational use at t r o m s ~ satellite station (pedersen 1982). for testing the implemented sst algorithm, a noaa data set from the summer 1981 covering the island jan mayen was applied (see fig. 3) (pedersen 1982). radiosonde data from the meteorological station at the island were applied as input for atmospheric corrections of the sat ellite data. in situ sst measurements from the area around jan mayen made by ships were also available from the norwegian institute for marine research. the resulting atmospheric corrected sst image is presented in fig. 4. the scale at the top of the image gives the relationship between the grey levels and the surface temperatures. the scale number 1.25 means that the surface temperature is within the range 1-1.5deg. centigrade. the island jan mayen is located almost in the centre of the image. comparisons of the satellite and the in situ temperatures show an average absolute difference of 1 deg kelvin. for all comparisons, the satellite measurements were systematically below the in situ measurements. the observed difference agrees well with the commonly accepted error achievable from a physical model, single thermal infrared band algorithm (pedersen 1982). the increased spatial resolution of the tm ther mal infrared channel, as compared to the avhrr, offers the possibility of applying the tm for studies of the surface temperatures in the coastal zone and within the fjords. the image presented in fig. 5 is a i,andsat-s/tm thermal infrared sub-scene covering the t r o m s ~ area. tromsb is located in the upper right corner of the ocean surface temperatureand colour studies f r o m satellites 7 fig. 3. approximate geographical location of data sets presented in this paper. a = jan mayen, b = tromse. image. the scale in the bottom left corner gives the correspondence between the grey levels and the surface temperatures. the colour-tempera ture scale was calibrated using surface tem peratures measured at known image locations. by combining the thermal infrared band with a near infrared band (0.764.90 pmj, areas of land have been blanked out. when the data set was acquired (3 june 1984), the sea current around the island tromsp, was moving north (up in the image). relatively warm surface water (c. 10deg. centigrade) is trans ported upwards from balsfjord (centre right in the image). two bridges extend from the island of t r o m s ~ , one to the east and one to the west. as the water flows under the bridges, the supports cause a turbulent mixing of the warm surface water with the colder sub-surface water which is clearly observed in the image. in the centre of the image, there is an area 8 janpetter pedersen fig. 4. sst image from jan mayen (centre of image). image based on noaa/avhrr data read out at troms0 satellite station 20 august 1981. thc scale at the top of the image gives the relationship between the grey levels and the temperatures. a scale value of e.g. 1.25 means that the surface temperature is within 1 . and 1.5 deg. centigrade. where the surface water temperature is approxi mately 2-3 deg. below that of the surrounding areas. this is caused by strong turbulence in the narrow sound between the two large islands. notice also that there is a small island located in fig. 5. landsat-s/thematic mapper sst image covering the tromse area. data read out at kiruna read out station 3 june 1984. for discussion of the image, see the text. the sound which strongly influences the water transport through the sound. in the bottom right of the image, a fjord which is an outlet for cold water can be seen. the cold water results from the river mblselva transporting cold snow-melt water from the nearby mountains into the fjord. conclusions ocean colour and surface temperature studies are best performed using optical remote sensing data. the major limitation regarding the optical data availability is the dependence upon the weather conditions. darkness and/or cloud cover strongly limit the data acquisition. experience from optical remote sensing in arctic regions show that, on average, there are only a few days during the year which are completely cloud free over large areas. despite these limitations, a number of important and interesting optical remote sensing appli cations have been demonstrated. the results obtained from nimbus/czcs data for ocean colour studies indicate that this category of remote sensing data represents an important potential for the mapping of the pro ductivity of remote, but important, ocean areas. the atmosphere represents the major problem in order to obtain acceptable geophysical data accuracy for operational applications. the at mosphere is a temporary and spatially varying medium, and the variations can not be given from a known law. in each case, the atmosphere needs to be described and the variations detected before reliable atmospheric corrections of the sub-sur face data can be obtained. for sst studies, the medium-resolution noaa/avhrr have been very useful in the research towards a better understanding of oce anic processes. although the coastal current off the western coast of norway has been known for long, noaa/avhhr surface temperature data offered the possibility t o perform simultaneous, multitemporary large area current studies. sat ellite data combined with model studies have increased the understanding of the coastal current generation mechanisms which is a combination of hydrographical and meteorological conditions. this research has resulted in an operational sys tem for coastal current forecasting. a number of algorithms are available for the sst generation. the single band, physical model ocean surface temperatureand colour studies f r o m satellites 9 achieves an accuracy of approximately 1 deg. kel vin, while the multiple band algorithms claim an accuracy of a few tenths of a kelvin (pedersen 1982). the results presented in this paper show that the satellite derived surface temperatures are consistently below the ship measured tempera tures. this is a very important result, and the absolute accuracy may for example be enhanced by the addition of a bias term into the algorithm. the reason €or not applying a bias term in this algorithm was primarily t o understand and dem onstrate the single band physical model for radi ative transfer at thermal infrared wavelengths in a coupled sea-atmosphere-sensor system (pedersen 1982). the medium resolution of the avhrr data limits the applications mainly to open ocean areas. the improved resolution of the landsat/tm offers the possibility to perform sst studies in the coastal zone and within the fjords. these applications have become more and more impor tant during recent years, because of the increased economical exploitation of the coastal areas. references gordon, h. r. & clark, d. k. 1980: atmospheric effects in the remote sensing of phytoplankton pigments. bound. layer meteorology 18, 295l313. gordon, h. r . , clark, d. k . , brown, j . w., brown, 0. b., evans, r. h. & broenkow, w. w. 1983: phytoplankton pigment concentrations in the middle atlantic bight: com parison of ship determinations and czcs estimates. applied optics 22(1), 2&36. guzzi, r., rizzi, r. & zibordi, g. 1987: atmospheric cor rection of data measured by a flying platform over the sea: elements of a model and its experimental validation. applied optics 26(15), 3043-3051. liou, k. 1980: a n introduction to atmospheric radiation. aca demic press inc., new york. maul, g. a. 1981: application of goes visible-infrared data to quantifying mesoscale ocean surface temperatures. j. geophys. res. 86(c9), 8007-8021. nasa 1984a: a prospectus for thematic mapper kesearch in the earth sciences. nasa technical memorandum 86149. nasa, gsfc, greenbelt, md. nasa 1984b: phytoplankton & surface patterns. nasa, jpl 400-221 2/84. nasa 1984c: tuna catch & ocean color. nasa, jpl 4w 225 2/84. pedersen, j.-p. 1982: atmospheric effects on infrared sea-surface temperature measurements from satellites. cand. real. thesis, univ. of tromscl (in nonuegian). pedersen, j.-p. 1987: a model for estimation and removal of the atmospheric effects on landsat/thematic mapper subsurface water radiances. internal report. imr, univ. of tromsb. schwalb, a. 1979: the tiros-n/noaa satellite series. n o a a technical memorandum ness 95. swain, p. & davis, s . 1978: remote sensing: the quantitative approach. addison-wesley publ. company, reading, mass. sturm, b. 1982: the atmospheric correction of remotely sensed data and the quantitative determination of suspended matter in marine water surface layers. paper presented at remote sensing summer school at dundee, scotland. weinreb, m. p. & hill, m. l. 1980: calculation of atmospheric radiances and brightness temperatures in infrared window channels of satellite radiometers. n o a a technical report n e s s 80. in search of an elusive antarctic circumpolar wave in ice extents: 1978-1996 per gloersen & norden e. huang sea for ease i n discerning an antarctic circumpolar wave in the perimeter of the ice pack. we construct a time series of the sea ice extents (essentially the area within the ice perimeter) in i -degree longitudinal sectors for the period 1978-1996, as observed with the multichannel microwave imagers on board the nasa nimbus 7 and the dod (dept. of defense) dmsp (defense meteorological satellite program) f8. fi 1. and f13 satellites. after converting the time series into complex numbers by means of a hilbert transform, we decompose the time series of the 360 sectors into its complex principal components (cpcs). effectively separating the spatial and temporal values. then we decompose the real and imaginary parts of the temporal portions of the first three cpcs (complex principal compenents) by empirical mode decomposition into their intrinsic modes, each representing a narrow frequency band, resulting in a collection of three cpcs for each intrinsic mode. finally, we reconstruct the data i n two different ways. first, we low-pass filter the data by combining all of the intrinsic modes o f each cpc with periods longer than two years. which we designate as low pass filtered. next, we select the intrinsic mode of each cpc with periods of approximately four years, which we designate the quasiquadrennial (qq) modes. the low-pass filtered time series show:, eastward propagating azimuthal motion in the ross and weddell seas, but no clearly circumpolar motion. the qq time series, on the other hand, clearly shows eastward propagating circumpolar waves, but with occasional retrograde motion to the west. p . g l o r r ~ e r i & n . e. hicurig, oceans and i ( 1, brurich. laborutory for hydrospheric processes nasmgoddurd spocr flight center, greenhrlt, m d 20771. usa. introduction propagation of sea ice protuberances around antarctica reported earlier by cavalieri & parkin son ( 198 1 ) and more recently by white & peterson (1996) and parkinson (1998) are examined in this paper with a new analysis technique appropriate for non-stationary time series: an empirical decomposition into intrinsic mode functions (huang et al. 1998). previously, a spectral analysis (gloersen & mernicky 1998) was applied to the interior of the antarctic sea ice pack using band limited discreet fourier transfonn of a shorter 1978-1987 sea ice time series. this provided phase distributions of two components observed in the ens0 signal, with periods of ca. 2.4 and 4.2 years, suggestive of a propagating wave i n the interior of the pack. in this paper, we examine sea ice extents and employ a novel combination of empirical mode decomposition (emd) recently described by huang et al. (1998) and complex singular value decomposition (csvd). csvd is used to separate the data into spatial and temporal components, and emd is used to divide the temporal signal into distinct modes, representing narrow frequency pass-bands. reconstruction of each intrinsic mode from its first three cpcs then permits construction of contour and three-dimen sional plots that reveal the presence or absence of spatial propagation of its respective nodes. analysis here. for ease in discerning an antarctic circum polar wave in the perimeter of the ice pack, we construct a time series of the sea ice extents (the gloersen & huang 1999: polar resetrrch 18(2), 167-173 167 (8) sectorized antarctic sea ice extents for 5 september 1996 '0 50 100 150 200 250 300 350 400 longitude a g i. antarctic sea ice extents in 1" meridional sectors on 1 september 1996. sum of the areas of pixels with ice concentrations of 15% or more) in 1-degree longitudinal sectors for the period 1978-1996, as observed with the multichannel microwave imagers on board the nasa nimbus 7 and the dod dmsp f8, f11, and f13 satellites. an example of the data is shown in fig. 1 for a typical day in austral winter. next, complex singular value decomposition (csvd) is used to decompose the time series of the 360 sectors into its principal components, after subtracting its linear trend line, effectively separ ating the spatial and temporal values. the results of the csvd procedure can be expressed as: (1) y(3322,360) = u(3322,360) * s(360,360) * v(360,360)' where the original data have been subjected to a hilbert transform to produce a complex data vector matrix, y. y is represented by the product of two complex unitary matrices, u, which contains the temporal information for each of the 360 cpcs and v, which contains the spatial information for each of the cpcs. s is a diagonal matrix of real eigenvalues. the prime on v denotes the matrix transpose. the number 3322 corresponds to the number of data days in the 18.2 year time series (including a 21 day data day gap in the dmsp f8 imager record), which has been interpolated with a modelled seasonal cycle (gloersen, campbell et al. 1992). the spatial and temporal factors of the real part of the first three principal components are shown in fig. 2. plots of the eigenvalue ratios of the cpcs and also of the cumulative fraction of the signal in the first n modes (obtained by taking the ratio of the sum of the eigenvalues of the first n modes and the sum of all the eigenvalues) are shown in figs. 3a and b. fig. 3b indicates that about 34% of the signal is contained in the first three cpcs. fig. 3a indicates that the amplitude of the fourth cpc is about 11 % of the first. thus, we need utilize only the first three cpcs to obtain a reasonable approximation to the original signal and to visualize any circumpolar wave that might be present. the temporal portions of the first three cpcs are processed by means of empirical mode decom position (emd) (huang et al. 1998) into their intrinsic modes (im), resulting in a collection of two or three cpcs for each intrinsic mode. it is important to note that the presence of several intrinsic modes for each cpc indicates that they are multi-modal. in particular, visual inspection of the temporal factor of cpc 1 (fig. 2b) might lead one to conclude that it contains only the seasonal cycle but, as is shown later, this is far from the case. a simplistic description of this method of sifting a data vector, y(n), into nearly orthogonal intrinsic modes follows: 1. we obtain two vectors containing the extrema 2. we fit the maxima and minima of these two vectors with cubic splines to produce two new vectors of length n. 3. we take the average of these two vectors to form a third new vector, ml(n). 4. the first intrinsic mode is then obtained by: c1 = yb) m1(n). 5. we repeat steps 1-3 on ml(n) to obtain m*(n). 6. the second intrinsic mode is then obtained by: c2 = ml(n) mz(n). i. we imitate steps 5-6 (i-2) times until c, contains less than one whole oscillation (c, = of y b ) . m1-1 mi>. this process usually converges for i less than 11. the actual method is more complicated than this in that there are conditional tests for assuring that the 168 in search of an elusive antarctic circumpolar wave in sea ice extents (a) real spatial parts of the 1st three complex pcs of the sectonzed pa extents (b) real temparal park of the 1st three complex pcs of the sectorized pa extsnts -003l , ~ ,l-. 80 82 84 86 88 90 92 94 96 fi,q. -7. real parts ot the first 3 complex principal components or the time series o f the antarctic sea ice extents i n 1 meridional hectors: ( a ) the apatial part: ( b ) the temporal part number of zero-crossings equals the number of extrema. for how many time series points are allowed between the extrema of the various modes, or how many are allowed between the extrema of the curvatures of the modes. if the input criteria are judiciously selected, the resultant modes are nearly orthogonal. a benefit of this approach is that the oscillations in the various modes are confined to narrow instantaneous frequency bands, greatly simplifying the inter pretation of the results. another benefit is that the original signal (within machine accuracy) is regained when the modes are added back together, an indication that spurious signals have not been introduced as a result of the decomposition. the intrinsic modes of cpcl are shown in fig. 4. cpcl appears to have 8 distinct oscillatory modes. the first mode contains the day-to-day fluctuations in the sea ice extent attributable to fluctuations in the weather. there is a flat area surrounded by two transients in this record occurring at the time of the aforementioned 21 day gap in the data, reflecting the lack of single day fluctuations in the interpolated data. the second mode is largely semi-monthly oscillations. possibly related to the 14 day tidal frequency. the third mode appears to be largely monthly oscilla tions. with an irregular amplitude modulation envelope of an annual cycle. we interpret these oscillations as influence of the monthly oceanic tides on the edge of the sea ice. and the minima of the envelope reflecting the reduction of signal when the ice is at its annual minimum extent. the fourth mode is a mixture of periods, of unknown origin, longer than one month and shorter than one year. the fifth mode is what we shall call the seasonal, rather than annual, cycle because it is not a monochromatic sinusoid. the shape of mode differs from the model seasonal cycle described earlier (gloersen, campbell et al. 1992) that consisted of the weighted sum of five harmonics of the annual cycle, and was found to approximate closely the observed seasonal cycles. the differ ence is attributable to the inability of fourier analysis to produce a meaningful spectrum for a non-stationary phenomenon as discussed by huang et al. (1998). modes 6-8 are of the most interest in the context of our search for a circumpolar wave in the antarctic sea ice perimeter. their amplitudes are. respectively, about 0.25, 0.1 and 0.05 of the seasonal cycle amplitude (mode 5). modes 6 and 7 are quasibiennial and quasiquadrennial periods similar to those observed earlier in the hemispheric gloergen & huang 1999: p o l r r research ix(2). 167-173 169 (a) eigenvalues of cpcs of sectorized aa sea ice extents i 0 2 k \ --_. -_ .~ -. .-_ , 10 15 20 (b) eigenvalues of cpcs of sectorized aa sea me extents 77~1 ~ 0 2 5 , 1.i 0 2 0pc# 10 15 fig. 3. (a) eigenvalue ratios of the first 20 coinplex principal components. (b) percent of signal in the first n principal components, obtained from the ratio of the sum of the first n eigenvalues to their total sum. sea ice canopies with band-limited fourier analy sis of a 9 year nimbus 7 data record (gloersen 1995; gloersen, yu et al. 1996; gloersen & mernicky 1998) which we attribute to an atmo spheric or oceanic teleconnection with the el nifio and southern oscillation phenomena. mode 8 contains periods in the range 6-7 years, and was only hinted at in the earlier studies of the 9 year data set (gloersen 1995; gloersen & mernicky 1998). finally, the last mode (9) contains the residual trend of the data set remaining after the initial subtraction of the trend line obtained by ordinary least squares. although it displays some curvature, mode 9 cannot be described convin cingly as oscillatory. the similarity between the modal structure of each of the first three cpcs and the rapid fall-off of their eigenvalues permit reconstruction of the original signal from its first three cpcs to a good approximation. furthermore, the intrinsic modes of the original data can be reconstructed to a good approximation from the individual intrinsic modes of the first three cpcs. we have reconstructed the data in two different ways. first, to simulate the 3-7 year bandpass filter used earlier by white & peterson (1996), we have added together the intrinsic modes 7-9 of cpcl (and similar modes of cpc2 and 3) to reconstruct a low-pass filtered time series. this excludes the quasibiennial modes (mode 6 of cpc1) as well as the seasonal and shorter period modes. second, we isolate the quasiquadrennial (qq) mode (mode 7 in cpc1) to look for differences between the qq and low-pass filtered results. timeaongitude contours of the low-pass filtered data (fig. 5a) show eastward propagating azi muthal motion, but no complete circumpolar circuit. the most prominent one begins in about 1990, with the crest at about 220"e and the trough at about 320"e. the crest propagates eastward until about 1994, when it reaches about 40"e. the trough reaches 40"e in about 1992. the compli cated combination of stationary and propagating troughs may be seen from a different perspective in the three-dimensional contour diagram in fig. 170 in search of an elusive antarctic circumpolar wave in sea ice extents complex pnnupal component 2 2 . 2 1 i i " ' i 111 1 i1 ' 1 ' f ' \ / 1 1 1 l i $ 0 4 v ' 1 1 ' 1 ' ' i t n 5 3 0 = -5 x i 0 8 0 82 84 86 88 90 92 94 96 i \ a x 1080 82 84 86 88 90 92 94 96 80 82 5b. there seems to be a barrier between about 120-150"e (the part of the southern ocean south of the western pacific) that the propagating waves do not cross. the aforementioned barrier appears to be absent i n the propagation patterns of the qq modes shown in fig. 6. focusing again on two of the most prominent features, a trough beginning i n about 1984 at about 220"e propagates eastward to 360 'e u n t i l about mid-1 986, then regresses westward for about half a year, resuming the eastward propaga tion to reach 360"e once again in about 1994, and finally stopping at about 20'e i n about mid1995. thus, the trough propagated for about 1.5 circumpolar cycles at a rate of about 1 cycle i n 8 . . l j 84 86 88 90 92 94 96 years, as reported earlier (white & petersen 1996; white, pers. comm.). the adjacent crest, starting at about 220"e, begins i n about mid-1985. it propagates eastward, crossing the greenwich meridian in about 1985. there is a brief westward regression in about mid1989, after which the crest continues eastward to about 300"e in about mid 1995 at which point the it begins another westward regression. discussion white & peterson (1996) have reported eastward propagation of a circumpolar wave i n sea ice gloersen & huang 1999: p o h r rrseurch 18(2), 167-173 171 fig. 5 . (a) contour plot of the low-pass filtered data of the sectored antarctic sea ice extents reconstructed from the sum of the intrinsic modes with periods longer than three years of the first three principal components. wave crests are white and troughs are shades of gray. (b) three-dimensional plot of the data in (a). extents, as well as in sea level pressures, and sea surface winds and temperatures. the data were preprocessed by passing through a band-pass filter with admittance from 3 to 7 years. they analysed sea ice extents in 5" meridional sectors, and the other parameters along the 5 6 " s parallel. they interpreted the contour patterns on their resulting position-time diagrams as circumpolar waves propagating eastwards and completing the circular traverse in about a decade (white, pers. comm.). thus the low-pass filter procedure we report here should encompass the entire oscillatory behaviour band-passed through their filter. our initial motive in undertaking this investiga tion was to confirm and examine in detail the circumpolar wave in sen ice extents reported by white & peterson (1996). however. our sea ice extent results obtained with our low-pass filter do not agree with theirs. w e surmise that their binning of the sea ice extents into 5' sectors, limiting the spatial resolution to about 10" of longitude, may have bridged the "barrier" between 120-1.50" that we observe in our low-pass filtered results. alternatively, the high frequency end of their band-pass filter, a half-power point of three years, may suppress part of the signal admitted by our low-pass filter. certainly. when we eliminate oscillations of three years or less with our qq filter, our results are much more in agreement. the results we present here clearly demonstrate the necessity of using a complex number repre sentation of the time series in order to retain the circumpolar motion in the sea ice pack when applying singular value decomposition. our earlier attempt at observing the circumpolar motion with real numbers was not successful. the results demonstrate also that care must be used in selecting the appropriate filters and the need for high spatial resolution in order not to lose important details in the wave propagation. finally, we demonstrate that it is imprudent to presume that complex principal components in themselves represent fundamental modes of an oscillatory system. for instance, the first cpc shown here could easily be mistaken by inspection for the seasonal cycle. while it is true that the seasonal 172 in search of a n elusive antarctic c i r c u m p o l a r w a v e i n sea ice extents fig. 6 . ( a ) contour plot of the intrinsic seasonal niodc ot the sectored antarctic sea ice extents reconstructed from the qua\iquadrennial (qq) parts of the first three principal cotiiponents. wave crests are white and troughs are shades of gray. (h) three dimensional plot of the data in (a). cycle is the largest oscillatory component of the first cpc, we have shown that the first cpc also has seven other significant oscillatory modes. w e intend to apply this technique also to the interior of the ice pack and to nearby sea surface temperatures and winds in an attempt to elucidate our present observations. ai.~rrou.le[l,~rnief~~.s. thia research was supported hy the office of polar program, nasa headquarters. references cevalieri. d. j. & perkinson. c. l. 1981: large-scale variations i n observed antarctic sea ice extent and associated a m o s pheric circulation. hfotirhl~ wrtrthcr rev. 109. 2323-2336. cavalieri. d. j., gloersen, p.. pnrkinson, c. l., comiso. j. c'. & zwally. h. j. 1997: observed asymmetry i n glohnl ski ice changes. si.ierwr 27x. i 104-1 106. gloersen. p.. campbell. w. j., cavalier. d. j.. coniiso. j . c.. parkinson, c. l. & zwally, h. j . 1993: arctic and anlarcric seii ice. 1978-1987: satellite passive microwave ohservations and analysis. nasa s p s l l . 319 pp. washington, d.c.: government printing office. gloersen. p. 1995: modulation of hemispheric sea ice covers by e n s 0 events. ntlrirre 373, 503-508. gloersen. p., y u . j . & mollo-christensen. e. 1996: oscillatory behavior i n arctic sea ice concentrations. j . ceophys. rrs. 101, 6641-6650. gloer5en. p. & mernicky, a. 1998: oscillatory hehavior in antarctic sea ice concentrations. i n m . 0. jeffries (ed.): antciri~ii. sell ice: physicul processes. intermtiom atid riwicibilin. antarct. rrs. ser. 74, 161-171. huang. n . e.. shen. z., long, s. r., wu. m. c.. shih, h. h., zheng. q., yen, n.-c., tung. c. c. & liu. h. h. 1998: the empirical mode decomposition and the hilhert spectrum for nonlinear and tionstationary time series analysis. proi.. r. s. lond. scr. a 4.54, 903-995. parkinson. c. l. 1998: length of the sea ice seabon in the southern ocean, 1988-1994. i n m. 0. jeffries (ed.): antarctic sc(i ice: plry.sictr1 proi~r.sse.s. inteructiom cind rariahilin. antrwt. res. srr. 74, 173-1 86. white, w. 6 . & peterson. r. g. 1996: an antarctic circumpolar wdve i n surface pressure, wind. temperature. and sea-ice extent. noritre 380, 699-702. gloersen & huang 1999: polar research 18(2), 167-173 173 the role of the microbial loop in antarctic pelagic ecosystems farooq azam, david c. smith and james t. hollibaugh azam, f., smith, d. c. & hollibaugh, j . t. 1991: the role of the microbial loop i n antarctic pelagic ecosystems. pp. 239-243 in sakshaug, e., hopkins, c. c. e. & 0ritsland. n . a. (eds.): proceedings of the pro mare symposium on polar marine ecology. trondheim. 12-16 may 1990. polar research l o ( 1 ) . the paradigm of the pelagic food web organization in antarctic waters is undergoing fundamental revision due to recent evidence that large fractions of material and energy flow through the microbial food web. we suggest that, because of the unique antarctic ecosystem conditions, the microbial food web performs some roles that are fundamentally different from those in oligotrophic temperate and tropical waters: 1) during winter, bacterial production, at the expense of slow-turnover dom (dissolved organic matter) from the previous summer, could be a significant factor in the survival of overwintering animal populations; 2) microbial regeneration of ammonium in nitrate-replete antarctic waters may spare the reductants necessary for nitrate assimilation and thus enhance primary productivity of deep-mixed light-limited phytoplankton; and 3) the small diatoms and phytoflagellates which dominate the antarctic pelagic primary production are apparently directly digestible by the metazoan herbivores, whereas cyanobacteria which dominate the primary productivity in lower latitude oligotrophic waters are not digestible by the metazoan herbivores. these roles performed by the microbial loop may, in part, explain why antarctic waters, in contrast to the lower latitude oligotrophic waters, have high levels of tertiary productivity despite low primary productivity. farooq azam and david c . smith, scripps institution of oceanography, university of california, son diego a-002, la jolla. california 92093, usa; james t . hollibaugh, tiburon cenier for ecological research, san francisco state university, tiburon, california 94920, usa (revised january 1 9 9 1 ) . introduction the classical notions of pelagic food web organ ization in antarctic waters are undergoing fun damental revision (hewes et al. 1985). for long it had been believed that material and energy flows occurred dominantly along a linear food chain: large diatoms + krill + whales, seals, birds, etc. the idea of a simple and short food chain was appealing because it was consistent with the widely held perception of very high tertiary production in antarctic waters. recent evidence suggests, however, that a large fraction of primary production is due to picoand nanoplankton rather than large diatams. brokel (1981) showed that small (<20 pm) phytoplankton comprised 73% of the chlorophyll a and 83% of the primary production in an extensive areal coverage between the bellingshausen sea and south geor gia. hewes et al. (1983), after performing a com prehensive circumpolar sampling, showed the generality of the results of brokel (1981) regard ing the significance of small autotrophs (the dom inance of picoand nanoplanktonic autotrophs is, however, not the case in coastal blooms; holm hansen et al. 1989). a second departure from the classical view is the realization that antarctic waters are oli gotrophic in terms of primary production in spite of the high residual nutrients. we use the term “hypoproductive” in describing these waters in order to distinguish them from the oligotrophic waters in lower lattitudes where low primary pro ductivity is due t o low nutrient concentrations. primary productivity rates for the region are on the order of 100-300 mg c m-* d-’ (holm-han sen et al. 1977; brokel 1981; el-sayed & taguchi 1981), which is comparable to lower latitude oli gotrophic regions. the focus on the small organisms and the hypo productive view of the southern ocean has now uncovered a dynamic microbial food web with potential for substantial energy and material transfer. previous notions that antarctic waters are too cold to permit bacterial growth (sorokin 1971) have been refuted by measurement of bac terial abundance and growth rates which have been found to be comparable to measurements from lower latitude open ocean waters (hodson et al. 1981; hanson et al. 1983; fuhrman & azam 1980; azam et al. 1981; rivkin 1991). two ques tions are now being asked: how can the microbial 240 f. a z a m , d. c . smith r j . t . hollibaugh food web be incorporated into the structure and dynamics of the antarctic pelagic food web and, given the unique physicochemical characteristics of the antarctic ocean. is the ecosystem role performed there by the microbial loop different from that in the lower latitude oligotrophic waters? this paper suggests that the microbial loop in antarctic waters performs some roles that are fundamentally different from roles performed in lower-latitude oligotrophic waters. w e believe that this is due to the unique ecosystem conditions which include high residual nutrients, extreme seasonality of solar radiation, and the wind-driven deep mixing of the plankton. finally, we propose ways of integrating the microbial loop activities with the antarctic pelagic ecosystem dynamics. we have taken the liberty of generalizing from the limited amount of available data for the pur pose of stimulating discussion and formulating new testable hypotheses. transfer of bacterial production to protozoa and metazoa in temperate and tropical waters bacterial car bon demand is equal to roughly one-half of the primary production which becomes dissolved and follows the idealized pathway: d o m ---* bac teria -+ protozoa + metazoa (azam e t al. 1983; cole et al. 1988). in this pathway bacteria salvage the energy lost t o the particulate food web as dom and potentially transfer it to tertiary con sumers. in antarctic waters the dom-based bac terial production could be a source of food for metazoa during summer, and particularly during the dark winter in the absence of primary pro duction. bacterial production during the austral spring and summer in open ocean waters is in the range of 1 to few mg c m 3 d l (azam et al. 1981; hanson et al. 1983) while the rates in coastal waters can be higher. in antarctic waters mic roflagellates and ciliates avidly consume bacteria (garrison et al. 1986: lessard & rivkin 1986: buck & garrison 1988). marchant & nash (1986) found that krill can ingest organisms in the size range of flagellates and ciliates (few t o few tens pn) although large diatoms are preferred (holm hansen & huntley 1984). some of the bacterial production could thus be potentially available to metazoa, including krill. from work in temperate and tropical waters, i t is commonly believed that bacterial biomass is largely mineralized within the multitrophic level microbial loop (ducklow e t al. 1985). however. others (king e t al. 1980; azam & ammerman 1984; crocker e t al. 1991) found that bacteria can b e directly utilized by some specialist metazoa (e.g. pelagic tunicates) and by “unintentional bacterivores” which may ingest aggregated or particle bound bacteria. while direct measurements in antarctic waters have not been made, metazoa such as salps and krill may feed on free, particle-bound and aggregated bac teria. digestibility of phytoplankton by metazoa: consequences for trophic transfer efficiency an interesting, and possibly important, contrast should be noted here between the antarctic and the temperate or tropical food webs in low pro ductivity regions. antarctic waters d o not harbor cyanobacteria of the genus synechococcus (mar chant et al. 1987; letelier & karl 1989) which is responsible for a significant, even dominant, portion of the primary production in oligotrophic waters (li e t al. 1983; platt e t al. 1983). t h e antarctic picoand nanophytoplankton are mainly small diatoms or phytoflagellates. meta zoan herbivores apparently cannot digest syne chococcus (silver & bruland 1981; silver & alldredge 1981; johnson et al. 1982); their pro duction must be channeled through protozoa, which can digest synechococcus, to t h e higher trophic levels. this additional step in energy transfer would reduce the total energy transferred to the higher trophic levels. o n the other hand, the small diatoms and phytoflagellates which con stitute the nanoautotrophic biomass in antarctic waters a r e presumably ingested as well as digested by the herbivores including the krill (marchant & nash 1986). thus, a part of the picoand nanophytoplankton production in the antarctic waters might be transferred directly t o the larger grazers. this difference may, in part, explain why the antarctic waters have higher levels of tertiary productivity, despite low primary productivity. digestibility of the dominant primary producer (as in the antarctic waters) should hardly be surprising: indeed. i t is the indigestibility of the often-dominant primary producer (synecho coccus) in the temperate and tropical waters which seems intriguing. in any event. the con role of microbia; loop 241 sequence may be that i n antarctic waters the grazing food chain is qualitatively (enzymati cally?) better equipped to utilize the primary production and thus to support a high tertiary production. temporal variation in phytoplankton-bacteria coupling because of the extreme seasonality of solar radi ation (and therefore of carbon reduction) in ant arctic waters, the significance of bacterial production for the food web also varies seasonally. rivkin (1991) showed that in mcmurdo sound, antarctica, bacterial pro duction (30-90 mg c m-* d-’) in the early spring (august-october) was in fact 22 to 36-fold greater than the primary productivity. if we assume a 50% assimilation efficiency, then the bacterial carbon demand would be 44 to 72-fold greater than the primary production. bacterial pro duction was not unusually high, but the primary production prior to the bloom was extremely low (1.2-2.8 mg c i-’ d-’). the situation was dra matically reversed as the phytoplankton bloom started in mid-november and primary production completely dwarfed bacterial production (10 to 190-fold). however, the shift from virtually unmeasurable primary production to a strong bloom is an ice edge and coastal waters phenom enon; open ocean waters apparently do not experience a significant spring bloom. these results have implications for bacteria phytoplankton coupling and food web dynamics. during winter as well as during the pre-bloom period, bacterial production could contribute to the energy needs of protozoa as well as of larger animals. further, marchant (1990) proposes that choanoflagellates (which are eaten by krill) can directly utilize high molecular weight (>4000) polysaccharides. the possible significance of dom in supporting antarctic pelagic food webs raises the question of the source of dom during this dominantly heterotrophic period. it is generally assumed from work in temperate and tropical waters that dom is derived from phytoplankton or detritus by various mechanisms of exudation or solubilization. the extremely low chlorophyll a and primary productivity in the pre bloom waters make phytoplankton a minor con tributor to the dom and suggest that detrital sources of bacterial substrates may be more important. possible sources include the slow-turn over dom components carried over from the previous summer, and dom and pom derived from the generally rich sea-ice communities. it thus appears that strong seasonality of both bac teria and phytoplankton production may involve temporally and perhaps also spatially loose coup ling between primary production and bacterial utilization of organic matter via the accumulation of dom during the summer and its utilization during winter and early spring. the implicit assumption here is that a significant fraction of the dom pool turns over very slowly, with turnover times on the order of months rather than days. long-lived dom might include some polymers (e.g. complex carbohydrates) that are not readily hydrolysed. conceivably, some easily utilizable substrates when bound to (or conjugated with) “humic” or “fulvic” material might also become less readily accessible and thereby constitute a “nutritional buffer”. if this idea is correct it would have important implications for energy supply for metazoa during winter. remineralized nitrogen as an energy source nutrient regeneration is an important role of the microbial loop in the productivity mechanisms of the oligotrophic waters since it reduces the gravitational loss of nitrogen contained in sinking organic matter. in the antarctic waters, which generally have very high concentrations of plant nutrients sustained through physical processes, the role of the microbiota in reducing nitrogen loss via sinking would seem unimportant. however, nitrogen remineralization to am monium could enhance primary production by conserving energy within the depth range of grow ing phytoplankton. one hypothesis which attempts to explain why the nutrient replete ant arctic waters have only modest primary pro ductivity is that it is light-limited; wind-driven deep mixing reduces the mean irradiance experi enced by the cells (holm-hansen et al. 1989). it has been shown (ronner et al 1983; koike et al. 1986) that in antarctic waters 50-85% of the nitrogen demand for primary production is sat isfied by the regenerated ammonium despite the presence of 15-30pmol i ’ nitrate. the pref erence for ammonium over nitrate is a well-known phenomenon from a number of studies in ant 242 f. azam, d . c . smith & j. t . hollibaugh arctic waters and elsewhere (see dortch 1990 for review). ammonium uptake spares the reduction potential which the phytoplankton would other wise use to reduce nitrate to ammonium since up to one third of the reducing power produced by photosynthesis can be required to reduce nitrate (lasoda & guerrero 1979: syrett 1981). pref erence for ammonium over nitrate is generally maximal at low light conditions (but see thomp son et al. 1989). so, the microbial loop in ant arctic waters causes saving of reductant and potentially enhance carbon fixation through nitro gen remineralization by a fundamentally different mechanism than in temperate or tropical oli gotrophic waters. ammonium oxidation and car bon fixation by chemoautotrophic bacteria could be an additional input into antarctic food webs as reported for waters below the ross ice shelf, antarctica (horrigan 1981). synthesis the emergent role for the microbial loop in the southern ocean as compared to lower latitude oligotrophic waters include the absence of a com petitive advantage over the grazing food chain for the dominant autotrophic nanoplankton due t o the qualitative difference of the nanoplanktonic autotroph in antarctic waters (absence of syne chococcus). a second ecosystem role of the microbial loop is to channel dom into the particle phase of the food web via bacterial production, potentially enhancing energy supply to metazoa. this function of the microbial loop takes on added significance in antarctic waters during the dark winter when primary production is absent and all secondary production is presumably supported by a detritus based food web. this role is diminished during the austral summer where primary pro duction greatly exceeds bacterial production. finally, in low latitude oligotrophic waters, which are nitrogen-depleted, the microbial loop serves to efficiently remineralize nutrients and thereby tends to reduce nitrogen loss through sinking of organic matter. in antarctic waters conservation of energy. not the conservation of nitrogen in the upper waters, may be a critical factor in regulating primary production. acknowledgements. -this work was supported by nsf grants to f. azam and j . t . hollibaugh. references azam. f.. ammerman. j . & cooper. n . 1981: bacterio plankton distributional patterns and metabolic activities in the scotia sea. ant. 1. u.s. 16, 164165. azam. f.. fenchel. t . . field. j . g.. gray. j . s.. meyer-reil, l. a . & thingstad. f. 1983: the ecological role of water column microbes in the sea. m a r . ecol. p r o g . ser. 10. 257 263. azam. f. & ammerman. j . w . 1984: mechanisms of organic matter utilization by marine bacterioplankton. pp. 4 s 5 4 in 0. holm-hansen. l. bolis and r. gilles (eds.): marine phyroplankton and productiuiry. springer verlag. berlin. brokel. k . von. 1981: the importance of nannoplankton within the pelagic antarctic ecosystem. kieler meeresforsch. son derhefr 5 . 61-67. buck. k . r. & garrison. d. l. 1988: distribution and abun dance of choanoflagellates (acanthoedidae) across the ice edge zone in the weddell sea. antarctica. mar. biol. 98, 26s.269. cole. j . j . , find1ay.s. &pace, m. l. 1988: bacterial production in fresh and saltwater ecosystems: a cross-system overview. mar. ecol. prog. ser. 43, 1-10. crocker. k . m . . alldredge, a . l. & steinberg d . k. 1991: feeding rates of the doliolid. doliolerro gegenbauri. o n dia toms and bacteria. j . plankton res. 13. 77-82. dortch. 0. 1990: the interaction between ammonium and nitrate uptake in phytoplankton. mor. ecol. prog. ser. 61. 18>201 ducklow. h. w.. hill. s . m. & gardner. w. d . 1985: bacterial growth and the decomposition of particulate organic carbon collected in sediment traps. conr. shelf res. 4 , 445-464. el-sayed. s . z. & taguchi, s. 1981: primary production and standing crop of phytoplankton along the ice-edge in the weddell sea. deep-sea res. 28. 1017-1032. fuhrman, j . a. & azam. f. 1980: bacterioplankton secondary production estimates for coastal waters of british columbia, antarctia and california. appl. enuiron. mmobiol. 39, 1085-1095. garrison. d. l., gowing. m. m.. buck. k. r . , coale. s . l. & thomsen, h . a . 1985: microheterotrophs in the ice edge zone: an a m e r i e z study. ant. j. us. 21, 169-171. hanson. r.. lowery. h . , shafer. d . . sorocco, r . & pope, d. 1983: microbes in antarctic waters of the drake passage: vertical patterns of substrate uptake. productivity and bio mass in january 1980. polar b i d . 2 , 179-188. hewes. c. d., holm-hansen. 0. & sakshaug. e. 1983: nanoplankton and microplankton studies during the cir cumnavigation cruise. anf. j , us. 18, 169-171. hewes. c. d., holm-hansen, 0. & sakshaug, e. 1985: alter nate carbon pathways at lower trophic levels in the antarctic food web. pp. 277-283 in siegfried, w.. condy, p. and laws, r. (eds.): antarctic nutrient cycles and food webs. springer verlag. berlin. hodson. r.. azam, f., carlucci. a , . fuhrman. j . karl. d. & holm-hansen. 0. 1981: microbial uptake of dissolved organic matter in mcmurdo sound, antarctica. mar. biol. 61. 89-94. holm-hansen. 0.. el-sayed. s . z., franceschini, g. a . & cuhel. r. l. 1977: primary production and the factors con trolling phytoplankton growth in the southern ocean. pp. 11-50 in llano, g . a . (ed.): adaprarions within antarctic ecosystem. gulf. houston. holm-hansen, 0. & huntley, m. 1984: feeding requirements of krill in relation to food sources. 1. crust. biol. 4 . 156-173. role of microbial loop 243 marchant, h . j . , davidson. a . t. & wright, s. w. 1987: the distribution and abundance of chroococcoid cyanobacteria in the southern ocean. proc. nut. inst. polar res. symp. polar biol. i , 1-9. marchant. h. i. 1990: grazing rate and particle size selection by the choanoflagellate diaphanoeca grandis from the sea ice lagoon saroma ko, hokkaido. proc. nut. inst. polar res. symp. polar biol. 3 , 1-7. platt. t . . subba rao. d. v. & irwin, b. 1983: photosynthesis of picoplankton in the oligotrophic ocean. nature 30f. 702 704. rivkin, r. 1991: seasonal patterns of planktonic production in mcmurdo sound, antarctia. amer. 2001. 3. 5-16. ronner. u., sorensson, f. & holm-hansen, 0. 1983. nitrogen assimilation by phytoplankton in the scotia sea. polar res. silver, m. w. & alldredge, a. l. 1981: bathypelagic marine snow: deep-sea algal and detrital community. j. mar. res. 39, 501-530. silver, m. w. & bruland, k. w. 1981: differential feeding and fecal pellet composition of salps and pteropods. and the possible origin of deep water flora and olive-green 'cells'. mar. biol. 62.263-273. sorokin, y. 1. 1971: on the role of bacteria in the productivity of tropical oceanic waters. int. rev. ges. hydrobiol. 56. 1 48. syrett, p. j . 1981: nitrogen metabolism of microalgae. pp. 182 210 in platt. t. (ed.): physiological bares of phytoplankton ecology. bull. no. 210, canadian government publ. center, hull, canada. thompson, p. a . , levasseur. m. e. & harrison, p. j. 1989: light-limited growth on ammonium vs. nitrate: what is the advantage for marine phytoplankton? limnol. oceanogr. 34, 1014-1024. 2 . 137-147. holm-hansen, 0.. mitchell. b., hewes. c . & karl. d. 1989: phytoplankton blooms in the vicinity of palmer station. polar biol. 10.49-57. horrigan. s. g . 1981: primary production under the ross ice shelf, antarctica. limnol. oceanogr. 26. 37a382. johnson, p. w., xu, h.-s. & sieburth. j . mcn. 1982: the utilization of chroococcoid cyanobacteria by marine pro tozooplankters but not by calanoid copepods. ann. imt. oceanogr. paris 58. 297-308. king, k., hollibaugh. j. & azam, f. 1980: predator-prey interactions between the larvaeean oikopleura dioica and bacterioplankton in enclosed water columns. mar. biol. 56. 49-57, koike. i . , holm-hansen, 0. & biggs, d. c. 1986: inorganic nitrogen metabolism by antarctic phytoplankton with special reference to ammonium cycling. mar. ecol. prog. ser. 30. 105-116. lasoda. m. & guerrero, m. g. 1979: the photosynthetic reduction of nitrate and its regulation. pp. 363-408 in barber, j. (ed.): photosynthesis in relation to modelsystems. elsevier/ north-holland biomedical press, amsterdam. lessard, e. & rivkin. r. 1986: nutrition of microzooplankton and macrozooplankton from mcmurdo sound. ant. j. u.s. 21, 187-188. letelier, r. m. & karl, d. m. 1989: phyeoerythrin-containing cyanobacteria in surface waters of the drake passage during february 1987. ant. j. u.s. 2 4 , 185-188. li, w. k. w . , sukba rao, d. v., harrison. w. g., smith, i. c.. cullen. j . j . , irwin, b. & platt, t. 1983: autotrophie picoplankton in the tropical ocean. science 219. 292-295. marchant, h. & nash, g. 1986: electron microscopy of gut contents and faeces of euphausia superba dana. tokyo nut. inst. polar res. mem. 40. 167-177. novel terrestrial haul-out behaviour by ringed seals (pusa hispida) in svalbard, in association with harbour seals (phoca vitulina) research artcle novel terrestrial haul-out behaviour by ringed seals (pusa hispida) in svalbard, in association with harbour seals (phoca vitulina) christian lydersena, jade vaquie-garciaa, espen lydersenb, guttorm n. christensenc & kit m. kovacsa anorwegian polar institute, tromsø, norway; buniversity college of southeast norway, campus bø, norway; cakvaplan-niva, tromsø, norway abstract ringed seals (pusa hispida) are the most ice-associated of all arctic pinnipeds. in the svalbard area, this species has always given birth, moulted and rested on sea ice. in addition, much of their food has been comprised of ice-associated prey. recently, ringed seals have been reported to be using terrestrial substrates as a haul-out platform in some fjords on the west coast of spitsbergen. in many cases the seals involved are harbour seals (phoca vitulina), which are extending their distribution into new areas within the svalbard archipelago and which are being misclassified as ringed seals. however, this study reports that terrestrial haulout by ringed seals is also now taking place on rocks exposed at low tide as well as on the coastline. recent intrusions of warm atlantic water (with associated prey) have extended deep into the fjords of western spitsbergen, resulting in deteriorated ice conditions for ringed seals and expanded habitat for harbour seals. over the last decade, ringed seals have become more and more confined in coastal areas to narrow bands in front of tidal glacier fronts where arctic conditions still prevail. in one lagoon area, ringed seals are hauling out on intertidal mud flats in close association with harbour seals. land can likely replace sea-ice for many of the ringed seals haul-out needs. however, for the small dry-cold adapted ringed seal pups that are normally born in snow lairs on the sea ice, terrestrial haul-out is unlikely to be a viable solution because of predation and thermoregulatory stress. keywords arctic; behavioural plasticity; climate change; glacier fronts; lagoons; sea ice ringed seals (pusa hispida) are the most ice-associated of the arctic seal species; they are born on sea ice, they moult on sea ice, they rest on sea ice and they do much of their foraging in association with this habitat. in svalbard, norway, the prime breeding areas for ringed seals are land-fast ice areas in fjords that have active glacier fronts that protrude out into the ocean (lydersen 1998). in such areas, ice pieces calved from the glaciers freeze into the sea ice in late autumn and early winter and snow accumulates in drifts around these structures to depths that allow ringed seals to dig out a lair in the snow over a breathing hole in the ice. such lairs are constructed by adult ringed seals of both sexes and also by immature animals. the lairs provide shelter from harsh climate conditions (smith et al. 1991) and also afford some protection from predation since it takes some time for a predator to dig or smash through the roof of the lair giving the seals some time to escape into the water through the breathing hole (lydersen & gjertz 1986). ringed seal mothers give birth to their young in these lairs. the lairs are vital for the survival of the pup that weigh only a few kilograms at birth. each ringed seal has several breathing holes and lairs that it can move between if one structure is attacked. mothers will move very young pups from lair to lair, but if she is out feeding, pups are at risk because they do not enter the water alone when they are very young (lydersen & hammill 1993; lydersen & kovacs 1999). polar bears (ursus maritimus) and arctic foxes (vulpes lagopus) are the main predators of ringed seals when they are in their lairs (lydersen & gjertz 1986). if snow conditions are poor and the females are forced to give birth on the open ice in svalbard, the mortality rate of pups increases significantly; the defenceless pups fall prey to glaucous gulls in addition to being taken more easily by foxes and bears (larus hyperboreus; lydersen & smith 1989). when the pupping and breeding season is over in svalbard, around late may, the ringed seals go through their annual moulting period, when they replace all their hair and the outer layers of the skin. moulting peaks in early june, with some temporal spread among the various age and sex groups (carlens et al. 2006). availability of a haul-out platform is very important for this process to occur in an energetically efficient manner, and for ringed seals the preferred platform is ice. when the moulting season is over, ringed seals in svalbard either move offshore seeking areas containing 40–80% ice coverage or remain coastal, spending their time near tidal glacier fronts (freitas et al. 2008; hamilton et al. 2015, 2016). both areas provide high concentrations of food and access to ice-platforms contact christian lydersen lydersen@npolar.no norwegian polar institute, fram centre, langnes, tromsø no-9296, norway polar research, 2017 vol. 36, 1374124 https://doi.org/10.1080/17518369.2017.1374124 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1374124&domain=pdf (either in the form of sea ice or glacier ice) to rest. offshore seals leave the pack-ice areas late in the autumn, even if ice conditions are still favourable, reflecting their need to return to the overwintering/ breeding areas in the fjords of svalbard before freezeup. the ringed seals that remain close to the coast are already close to their overwintering/breeding habitat and simply become more sedentary as winter approaches. sub-adult ringed seals tend to adopt the offshore strategy, while larger adult animals tend to stay coastal (hamilton et al. 2015, 2016). during the last decade, influxes of atlantic water (cottier et al. 2005) with increasingly higher temperatures (spielhagen et al. 2011) have replaced arctic water masses in the fjords on the west coast of svalbard. consequently, sea ice has formed late in the season or in some years has not formed at all (lydersen et al. 2014). when sea ice forms late in the season there is generally not time for enough snow to accumulate, preventing ringed seals from being able to construct birth lairs. in recent years, the few areas that did have sea-ice in april have had unnaturally high densities of ringed seals. most pups that have been born on the open ice have been killed by predators. in addition, very little sea ice has been available for the post-breeding moulting period over the past decade as well, forcing some ringed seals to undergo this process in the water with increased energetic costs due to increased heat loss. during the last few years, local tour operators and trappers have reported ringed seals hauled out on shore. upon review of photographs taken of these seals, the reports have often turned out to be misidentified harbour seals (phoca vitulina). however, in some few areas, the reports have proven to be ringed seals that have started using intertidally exposed rocks as resting platforms. adolfbukta (fig. 1) is one such area, where ringed seals are now using rocks during low tide in the sea-ice free season for haul-out (fig. 2a). during the summer of 2016, ringed seals used intertidal mudflats in a lagoon in st jonsfjorden as a haul-out platform (fig. 1). these areas were shared with harbour seals (fig. 2b). this lagoon has been utilized as a capture site for ringed seal tracking studies in the past (in 1996, see gjertz et al. 2000, and in 2012, see hamilton et al. 2015; hamilton et al. 2016), but terrestrial haul-out has never before been observed in this area, nor have harbour seals been observed previously. four ringed seals instrumented with gps satellite relay data loggers (sea mammal research unit, university of st. andrews for more details on handling and instrumentation; see hamilton et al. 2016), in 2012 in this lagoon never hauled out in the lagoon during the seaice-free period (fig. 3); they hauled out exclusively on glacier ice pieces within the fjord. such ice platforms are available throughout the sea-ice-free season in this fjord; the tidewater glaciers in the area calve ice figure 1. map of svalbard where place names mentioned in the text are indicated. the red dot is where the ringed seals in fig. 2 (a) were hauled out and the green dot is where the mixed group of ringed and harbour seals in fig. 2b were hauled out. 2 c. lydersen et al. pieces routinely. however, these glacier ice pieces never enter the lagoon because of its shallow entrance. it is assumed that the ringed seals come into the lagoon in search of ice platforms (sea ice in lagoons freezes up earlier and stays longer than fjord areas due to fresher water and less wave action) or perhaps food (arctic char [salvelinus alpinus]). however, in 2016 all five ringed seals tagged inside the lagoon hauled out on shore within the lagoon, while also using glacier ice deep in the fjord to some degree (fig. 3). it is worth noting that in 2012, all of the tagged seals returned to the lagoon to haul out late in the season, following the formation of sea ice, which they used as a haul-out platform. harbour seals in svalbard constitute the worlds’ northernmost population of this species (prestrud & gjertz 1990; andersen et al. 2011). a recent study of space use by these seals showed that they had a strong preference for the west side of the svalbard archipelago, staying mainly in coastal areas over the continental shelf, and seldom entering the fjord systems (blanchet et al. 2014). blanchet et al. (2014) showed that their distribution was largely restricted to coastal areas that were heavily influenced by atlantic water. since both the temperature and influx of this water type is predicted to increase in the future in svalbard, environmental conditions in the archipelago are expected to become more favourable for harbour seals (blanchet et al. 2014; blanchet et al. 2015; hamilton et al. 2014). expansion of this “temperate” species is likely to be negative for the arctic ringed seals, which are already being stressed by reduced breeding habitat and declines of their favoured prey with the on-going borealization of the northern barents sea region (kovacs & lydersen figure 2. (a) ringed seals hauled-out on rocks in adolfbukta, svalbard; note glacier ice in the background (photo: anders voss thingnes). (b) three ringed seals (in the foreground – one with a satellite relay data logger) and two harbour seals in the background hauled out together on shore in st jonsfjorden, svalbard; the yellowish fur of the two harbour seals shows that they are still moulting (photo: guttorm n. christensen). polar research 3 2008; kovacs et al. 2011; kovacs et al. 2012; fossheim et al. 2015). dietary studies conducted in the late 1990s and early 2000s suggested significant overlap in prey types consumed by ringed seals and harbour seals in svalbard (andersen et al. 2004; labansen et al. 2007), but spatial separation of feeding areas likely minimized competition in this earlier period. co-habitation of terrestrial haul-out sites by these two species as described here was very surprising. it clearly indications that the two species are no longer spatially separated in the area; harbour seals have extended their range locally into the fjords in western svalbard. the behavioural plasticity displayed was particularly remarkable for the arctic ringed seals, which normally do not haul out communally and normally use only ice for haul-out. however, it has been speculated that during these times of dramatic change in ice conditions, some species will likely surprise us, with adaptive flexibility not yet considered possible (kovacs & lydersen 2008). it seems likely that the recent expansion of harbour seals into this area stimulated this new behaviour by the resident ringed seals. terrestrial haul-out would at least theoretically solve some issues for ringed seals in a warming arctic. this substrate could replace sea-ice as a moulting and resting platform. however, terrestrial substrates are unlikely to be successful replacements as a birthing and nursing habitat. ringed seal pups are small at birth – 4–5 kg (lydersen 1998) – and dry-cold adapted. they are born in a white furry foetal coat (lanugo) that insulates well in air (i.e., when dry) but not in water and the pups are born with very little subcutaneous fat (smith et al. 1991; lydersen et al. 1992). therefore, exposed pups would be both challenged thermally, and they would be easy prey for avian and mammalian predators. ringed seal pupping onshore has never been reported from svalbard. harbour seal pups in svalbard on the other hand are born at about 10–12 kg, have shed their lanugo in utero and are born with a subcutaneous blubber layer that enables them to be aquatic from the day they are born (jørgensen et al. 2001). despite the malleability in haul-out behaviour illustrated by the observation reported herein, such behavioural plasticity is unlikely to overcome the catastrophic consequences of loss of sea-ice breeding habitats on ringed seal pup survival and population health. another question that arises with these new observations of mixed-species haul-out between ringed seals and harbour seals is the potential for hybridization. these two species are currently classified in two separate genera, pusa and phoca, respectively (rice 1998; berta & churchill 2012). their breeding and moulting phenologies are somewhat different in that ringed seals normally pup in april and moult in may–june (lydersen 1998), while harbour seals pup in svalbard in late june and moult in july–august (see fig. 2b, in which the harbour seals are moulting on 19 july). both species mate toward the end of the lactation period, which would be may for ringed seals and july for harbour seals – but the likelihood that figure 3. track (lines) and haul-out sites (circles) for ringed seals equipped with satellite relay data loggers from capture date (july/august) to 20 september in (a) 2012 (n = 4) and (b) 2016 (n = 5) from the inner parts of st. jonsfjorden, svalbard. the end date for the tracks displayed here was set to 20 september to ensure that no ice had yet formed in the lagoon that could be used by the seals as a haul-out platform. the black asterisk in (a) indicates the location inside the lagoon where all seals from both years initially were captured. 4 c. lydersen et al. males of both species would be fertile well beyond these time periods is quite high. cross-breeding has been reported previously between other phocid seal genera (kovacs et al. 1997), namely pagophilus (p. groenlandicus, harp seal) and cystophora (c. cristata, hooded seal), which are morphologically much more dissimilar and have much more divergent mating behaviour than ringed and harbour seals. this study reports that terrestrial haul-out is now taking place by ringed seals in svalbard, even in areas where some ice platforms exist. this behaviour is shared with baltic ringed seals (härkönen et al. 1998) and freshwater ringed seals found in lake saimaa (pusa hispida saiimensis) and in lake ladoga (pusa hispida ladogensis) (sipilä & hyvärinen 1998). these freshwater seals live in very different environments with different climate and predation pressure compared to the arctic ringed seals. nevertheless, it demonstrates some of the adaptive flexibility within ringed seals as a species. the expansion of harbour seals into areas previously occupied only by ice-associated seal species in the svalbard archipelago, and the observations reported herein of communal haul-out by ringed seals and harbour seals warrants further study of the ecology of these two species in this area as a model of responses to changing conditions in a warmer arctic. acknowledgements we would like to thank anders voss thingnes for providing the photograph in fig. 2a, and oddmund isaksen for help with the fieldwork. disclosure statement no potential conflict of interest was reported by the authors. funding this work was supported by the norwegian polar institute’s centre for ice, climate and ecosystems and the norwegian research council. references andersen l.w., lydersen c., frie a.k., rosing-asvid a., hauksson e. & kovacs k.m. 2011. a population on the edge: genetic diversity and population structure of the world’s northernmost harbour seals (phoca vitulina). biological journal of the linnean society 102, 420– 439. andersen s.m., lydersen c., grahl-nielsen o. & kovacs k. m. 2004. autumn diet of harbour seals (phoca vitulina) at prins karls forland, svalbard, assessed via scat and fatty-acid analyses. canadian journal of zoology 82, 1230–1245. berta a. & churchill m. 2012. pinniped taxonomy: review of currently recognized species and subspecies, and evidence used for their description. mammal review 42, 207–234. blanchet m.-a., lydersen c., ims r.a. & kovacs k.m. 2015. seasonal, oceanographic and atmospheric drivers of diving behaviour in a temperate seal species living in the high arctic. plos one 10, e0132686, doi: 10.1371/ journal.pone.0132686 blanchet m.-a., lydersen c., ims r.a., lowther a.d. & kovacs k.m. 2014. harbour seal phoca vitulina movement patterns in the high-arctic archipelago of svalbard, norway. aquatic biology 21, 167–181. carlens h., lydersen c., krafft b.a. & kovacs k.m. 2006. spring haul-out behavior of ringed seals (pusa hispida) in kongsfjorden, svalbard. marine mammal science 22, 379–393. cottier f., tverberg v., inall m., svendsen h., nilsen f. & griffiths c. 2005. water mass modification in an arctic fjord through cross-shelf exchange: the seasonal hydrography of kongsfjorden, svalbard. journal of geophysical research—oceans 110, article no. 12005, doi: 10.1029/ 2004jc002757 fossheim m., primicerio r., johannesen e., ingvaldsen r. b., aschan m.a. & dolgov a.v. 2015. recent warming leads to a rapid borealization of fish communities in the arctic. nature climate change 5(7), doi: 10.1038/ nclimge2647 freitas c., kovacs k.m., ims r.a., fedak m.a. & lydersen c. 2008. ringed seal post-moulting movement tactics and habitat selection. oecologia 155, 193–204. gjertz i., kovacs k.m., lydersen c. & wiig ø. 2000. movements and diving of adult ringed seals (phoca hispida) in svalbard. polar biology 23, 651–656. hamilton c.d., lydersen c., ims r.a. & kovacs k.m. 2015. predictions replaced by facts: a keystone species’ behavioural responses to declining arctic sea-ice. biology letters 11, article no. 20150803, doi: 10.1098/ rsbl.2015.0803 hamilton c.d., lydersen c., ims r.a. & kovacs k.m. 2016. coastal habitat use by ringed seals pusa hispida following a regional sea-ice collapse: importance of glacial refugia in a changing arctic. marine ecology progress series 545, 261–277. hamilton c.d., lydersen c., ims r.a. & kovacs k.m. 2014. haul-out behaviour of the world’s northernmost population of harbour seals (phoca vitulina) throughout the year. plos one 9, e86055, doi: 10.1371/journal.pone.0086055 härkönen t., stenman o., jüssi m., jüssi i., sagitov r. & verevkin m. 1998. population size and distribution of the baltic ringed seal (phoca hispida botnica). nammco scientific publications 1, 167–180. jørgensen c., lydersen c., brix o. & kovacs k.m. 2001. diving development in nursing harbour seal pups. the journal of experimental biology 204, 3993–4004. kovacs k.m., aguilar a., aurioles d., burkanov v., campagna c., gales n., gelatt t., goldsworthy s., goodman s.j., hofmeyr g.j.g., härkönen t., lowry l., lydersen c., schipper j., sipilä t., southwell c., stuart s., thompson d. & trillmich f. 2012. global threats to pinnipeds. marine mammal science 28, 414–436. polar research 5 https://doi.org/10.1371/journal.pone.0132686 https://doi.org/10.1371/journal.pone.0132686 https://doi.org/10.1029/2004jc002757 https://doi.org/10.1029/2004jc002757 https://doi.org/10.1038/nclimge2647 https://doi.org/10.1038/nclimge2647 https://doi.org/10.1098/rsbl.2015.0803 https://doi.org/10.1098/rsbl.2015.0803 https://doi.org/10.1371/journal.pone.0086055 kovacs k.m. & lydersen c. 2008. climate change impacts on seals and whales in the north atlantic arctic and adjacent shelf seas. science progress 91, 117–150. kovacs k.m., lydersen c., hammill m.o., white b.n., wilson p.j. & malik s. 1997. a harp seal x hooded seal hybrid. marine mammal science 13, 460–468. kovacs k.m., lydersen c., overland j.e. & moore s.e. 2011. impacts of changing sea-ice conditions on arctic marine mammals. marine biodiversity 41, 181–194. labansen a.l., lydersen c., haug t. & kovacs k.m. 2007. spring diet of ringed seals (phoca hispida) from northwestern spitsbergen, norway. ices journal of marine science 64, 1246–1256. lydersen c. 1998. status and biology of ringed seals (phoca hispida) in svalbard. nammco scientific publications 1, 46–62. lydersen c., assmy p., falk-petersen s., kohler j., kovacs k.m., reigstad m., steen h., strøm h., sundfjord a., varpe ø., walczowski w., weslawski j.m. & zajaczkowski m. 2014. the importance of tidewater glaciers for marine mammals and seabirds in svalbard, norway. journal of marine systems 129, 452–471. lydersen c. & gjertz i. 1986. studies of the ringed seal (phoca hispida schreber 1775) in its breeding habitat in kongsfjorden, svalbard. polar research 4, 57–63. lydersen c. & hammill m.o. 1993. diving in ringed seal (phoca hispida) pups during the nursing period. canadian journal of zoology 71, 991–996. lydersen c., hammill m.o. & ryg m. 1992. water flux and mass gain during lactation in free-living ringed seal (phoca hispida) pups. journal of zoology, london 228, 361–369. lydersen c. & kovacs k.m. 1999. behaviour and energetics of ice-breeding, north atlantic phocid seals during the lactation period. marine ecology progress series 187, 265–281. lydersen c. & smith t.g. 1989. avian predation on ringed seal phoca hispida pups. polar biology 9, 489–490. prestrud p. & gjertz i. 1990. the most northerly harbor seal, phoca vitulina, at prins karls forland, svalbard. marine mammal science 6, 215–220. rice d.w. 1998. marine mammals of the world. systematics and distribution. society of marine mammals special publication 4. lawrence, ks: allen press. sipilä t. & hyvärinen h. 1998. status and biology of saimaa (phoca hispida saimensis) and ladoga (phoca hispida ladogensis) ringed seals. nammco scientific publications 1, 83–99. smith t.g., hammill m.o. & taugbøl g. 1991. a review of the developmental, behavioural and physiological adaptations of the ringed seal, phoca hispida, to life in the arctic winter. arctic 44, 124–131. spielhagen r.f., werner k., sørensen a., zamelczyk k., kandiano e., budeus g., husum k., marchitto t.m. & hald m. 2011. enhanced modern heat transfer to the arctic by warm atlantic water. science 331, 450– 453. 6 c. lydersen et al. abstract acknowledgements disclosure statement funding references the 'common vole' in svalbard identified as microtus epiroticus by chromosome analysis karl f r e d g a , maarit jaarola. rolf anker ims, harald steen and nlgel g . yoccoz fredga, k . , jaarola, m., ims, r. a , , steen, fi. & yoccoz. n. g. 1990: the 'common vole' in svalbard identified as microtus epiruticur by chromosome analysis. polar research 8, 283-2y0. the chromosomes were studied in six individuals from a population of microtus from grumantbyen, svalbard, and in six microtur arualis (pallas 1778) from lauwersee, holland. it was shown that the voles from svalbard did not belong, as earlier supposed, t o the species m . arualis (2n = 46) but to m . epiroticus (ondrias, 1966) (2n = 54). we suggest that the svalbard voles were introduced by man between 1920 and 1960 together with hay on russian ships from the vicinity of leningrad, ussr. karl fredga and maarit jaarola, department of genetics, uppsala university, p.o. b o x 7003. s-750 0 7 uppsala. sweden: rolf a n k e r ims and harald steen, department of biology, division of zoology, university of oslo, p.o. b o x 1050 blindern, n-0316 oslo 3 , norway; nigel g. yoccoz, deparrment of biology, division of zoology, uniuersify of oslo. p.o. box i050 blindern, n-0316 oslo 3 , norway. or: laboratoire de biometrie, unioersitk claude bernard l y o n 1. 69622 villeurhanne cedex. france; february 1990 (revised july 1990). ' in 1960 a member of the finnish zoological expedition to svalbard found the first vole in svalbard at longyearbyen. in 1964 and 1965 voles were abundant in the longyearbyen village and district and several specimens were collected (nyholm 1966). in 1975 voles were trapped at hotellneset, longyearbyen, and in 1976 at fuglefjellet, grumantbyen, w adventfjorden, by alendal (1977). the voles collected in the 1960s and 1970s were identified as microtus aruulis (pallas 1778) on morphological grounds. a more recent report describes voles collected at coles bay and barentsburg as m . arualis (bolshakov & shubnikova 1988). the present study is part of a comparative ecological investigation aimed at revealing which cir cumstances make it possible for a southern vole species to establish itself in arctic conditions. in order to find a relevant reference population it was important to find out, if possible, the origin of the ancestors. microtus must have been brought to svalbard by man and according to alendal (1977), the voles might have been introduced by whale and walrus hunters from holland in the 17th or 18th century. this conclusion was based on the identification of the specimens captured in svalbard as microtus arvalis. in 1972 a new microtus species was described by meyer et al. it was called m . subarvalis, but since this name is an absolute homonym of a fossil species, microtus subarualis heller 1933, the name was changed to m . epiroticus ondrias 1966 (see honacki et al. 1982).* it is a sibling *recently. the namc microtus rossiaemeridionrrlis ognev 1924 was applied t o this species (malygin 1983: malygin & yatscnko 1986). fifteen spccimens of the 'common volc' were collcctcd in the type locality (aninsk region. voronej district) of the taxon m . arualis rossiaemeridionalis ognev 1924. all fiftccn had 2n = 54 and since, according to malygin & yatscnko (1986). m . arualis (2n = 46) docs not cxist i n this area they conclude that thc animals described by ogiicv also must have had 54 chromosomes. consequcntly, the sibling spccies with 54 chromosomes should be called m . russiaemeridiorralls ognev 1924 and not m . epiroticus ondrias 1966. howevcr, we arc not willing to accept their conclusion for the following reasons: i . we can not kriow which taxon ogncv described in 1924 since the two sibling spccies of 'common voles' can not he distinguished by their external morphology. he did not study the characters that distinguish the two (chromosomes. blood proteins or sperm). 2. m . arualis 'arualis' and m . arualis 'ohvcurus' occur west and east of voroncj, respectivelv. 1s it possiblc to excludc the present occurrence of either of these at the type locality of m . a. rossiaemeridiormlisis" only 15 specimens were invcstigatcd. also. the distribution of thc two sihling spccics may have changcd since 1924 ('?)when the holotypc o f ro.\iormrridionali.~ was collected. 3. wc recommend that this question bc considcred by the intcrnational commission on zoological nomenclature. according to article 80, status of casc under consideration (a) (international code of zoological nomenclature 1985), existing usage is to he maintained until a ruling of the commission is published, prcscntly, the twoauthoritative taxonomic references (niethammcr & krapp 1982; honacki et al. 1982) usc the name m . epiroticus ondrias 1966. for thcse reasons we prefer to use the name m . epiroticus in the present article. 284 k . fredga et al. f i r . i d i d h u t i o n of m . u r u u l k (solid linc) and m . rpirulicus (\hudowcd) in europc and western ussr (haacd o n matygin s: orlov 1974; k r i l ci al. 1980: nicthammcr 8: krapp 1982: vorontsov el al. 1984). species of m. arualis, and is found within the central part of the vast distribution area of m . arualis (fig. 1). t h e new species cannot be distinguished from m . arvalis by external morphology, but t h e two species have charac teristic karyotypes: m. epiroticus has 2n = 54 and m . arvalis has 2n = 46. there is also a difference between the two species i n the size and shape of t h e spermatozoa and with regard to several proteins (mejer et al. 1972, 1973: sakiyan et al. 1984). since both m . arvalis and m. epiroticus potentially could have been introduced from russia with supply ships to some of the permanent russian settlements in svalbard, it was important to study the chromosomes of the svalbard voles. the ‘common vole’ in svalbard 285 furthermore, the comparison of the chromosomes and the mitochondria1 dna of voles from svalbard with voles from holland and other parts of northern europe might solve the problem of origin and perhaps also tell something about the number of specimens introduced. we here show that the microtus, belonging to a viable population living in natural habitats in the surroundings of grumantbyen, isfjorden, are m . epiroticus and not m . arvalis as believed earlier (alendal 1977). material and methods during a two-week period in late august 1989, three of us visited localities in the isfjorden area where micrntus either had been captured or ‘seen’ according to alendal(1977). coles bay and some other localities were also checked (fig. 2). l o k m fig. 2. map of the isfjorden area. circle: voles caught during the prcsent study. stars: voles reported to be present by nyholni (1966). alendal (1977) o r bolshakov & shubnikova (1988). hut nor found by us examining thc loealitics in august 1989. trianglcs: localities with no earlier reports about vole occurrence, but examined by us in august 1989 with negative results. squares: localities previously reported to contain voles (alendal 1977; bolshakov & shubnikova 1988) but not cxarnined by us. 1 = grurnantbyen, 2 = longyearbyen, 3 = colesbay, 4 = kapp laila.5 = bjondhavna.ternpelfjellet, 6 = alkhornet, 7 = knpp l i m e . 8 = sassendalen. 9 = pyramiden, 10 = barentshurg. 11 = bellsund. each locality was first examined for signs of small rodents (grazing, runways or faeces) in grassy vegetation. such signs of microtus activity are conspicuous even at low densities. at places where signs were found multiple-capture live traps (type: ugglan) were set. only the area between bjarndalen, 2 km w longyearbyen, and coles bay (fig. 2) was found to be inhabited by microtus. signs of microtus activity were, however, most pronounced in the grassy slopes under fuglefjella and the animals seemed to prefer places on peat soil with lush vegetation of grass and herbs, interspersed with patches of boulders. generally, these preferred areas were on stable well-drained ground. approximately 100 live-traps were set for 2‘12 days in the surroundings of grumantbyen. a total of 46 individuals were caught, indicating a dense population. the animals were brought alive to the department of biology, university of oslo, where a breeding colony was established. fifty m . urvalis were live trapped in october 1989 at lauwersee, ne holland. all specimens were brought alive to the department of biology, university of oslo, where a breeding colony was established. six of the voles from svalbard and six from holland, 4males and2femalesof eachpopulation, were karyotyped. chromosome preparations were made from bone marrow by the direct method of fredga (1987). for gand c-banding the techniques of wang & fedoroff (1972) and sumner (1972) were used, respectively. results m . epiroticus the six voles studied from svalbard had identical autosomal karyotypes and males were xy, females xx. the chromosome number was 2n = 54 and all chromosomes but the smallest pair of autosomes were telocentric (fig. 3.4). the x chromosome was the largest of the complement and the y the next largest, but close in size to the largest autosome. this autosome was the only telocentric that could be identified without g banding. the rest of the single-armed autosomes decreased continuously in size. a g-banded karyotype is shown in fig. 3b. after c-staining, all autosomes showed centromeric c-bands (fig. 3c). the distal half of the x stained as a positive c-block and the entire y appeared dark after 286 k . fredga et al. fig. 3. karyotypes of male microtus epiroticur from grumantbyen, svalbard. a ) unbanded, b) g-banded, c) c-banded. boxed: sex chromosomes from a female with one normal and one deleted x chromosome (xd). arrows indicate the position of the centromeres in the sex chromosomes. preparations from bone marrow. bar = 10 pm. same magnification in a . b and c. the ‘common vole’ in svalbard 287 fig. 4. karyotypes of microtus arualis from lauwersee, holland. a) male, unbanded, b) female, g-banded, c) male, c-banded preparations from bone marrow. bar = 10 pm, same magnification in a . b and c. 288 k . fredga et al. c-staining. one of t h e females studied had o n e normal and one deleted x; a little more than half of t h e heterochromatic distal part was missing (fig. 3c). t h e karyotypes of t h e voles from svalbard a r e in perfect agreement with those of m . epiroticus from finland (fredga et al. unpublished) and from different parts of the ussr (vorontsov et al. 1984; mejer e t al. 1985). m . arvalis t h e six voles from holland had identical karyotypes (males xy, females xx). t h e chromosome number was2n = 46. t h e autosomes may be divided into two size groups: 5 large and 17 small pairs. all t h e large chromosomes and 13 of the small were bi-armed. four of the small chromosomes were acrocentric. t h e x chromosome was of intermediate size and metacentric, the y was the smallest of the complement and acrocentric (fig. 4a). a c-banded karyotype is shown in fig. 4b. after c-staining, centromeric blocks of heterochromatin were present in 10 of the small pairs, h bi-armed and 4 acrocentric (fig. 4c). t h e n f value was 84 (female). different populations of m . arvalis may be distinguished by their karyotypes ( k r a l & lyapunova 1975; zima & k r i l 1984). they all have 2n = 46 and 5 large, bi-armed chromosomes, but the number of small single-armed pairs varies, as well as the number of chromosomes with centromeric c-blocks. t h e karyotype of voles from this dutch population is similar (but not identical) t o that of voles from osnabruck in germany (camper1 1982). they both have 10 pairs with c-blocks and n o acrocentric without. however, t h e number of acrocentric pairs in the dutch population is 4 compared t o 3 in the german one. discussion t h e present chromosome study has shown that the voles collected in 1989 at fuglefjella, grumantbyen, belongto the species m . epiroticus. five individuals caught in 1976 in the same area by alendal (1977) were identified as m. arvalis, according t o guidelines from literature that did not distinguish arvalis from epiroticus. we were not able to find voles anywhere else, although attempts were made a t another seven sites (fig. 2). this means that we cannot exclude the possibility that the voles caught by earlier investigators at longyearbyen and its vicinities (nyholm 1966; alendal 1977), coles bay and barentsburg (bolshakov & shubnikova 1988) really were m . arualis. bolshakov & shubnikova (1988) pointed out, however, that microtus in svalbard needs t o be karyotyped t o confirm the identification of the species. t h e distribution of m . aroalis and m . epiroticus is shown in fig. 1. m . arvalis is present in western europe, from the atlantic coast and eastwards to about longitude 90"e in western siberia. m . epiroticus has a more limited distribution in the approximate middle third of this vast area. in europe m . epiroticus has its northernmost populations in finland and the southernmost on the balkan peninsula. these are also the two westernmost areas of its distribution. the type locality of m . epiroticus is in the epiros mountains in northwestern greece (kuzic e t al. 1y75). t h e two species exist sympatrically in many areas but appear t o occupy different habitats in the breeding season. in the winter m . epiroticus seems t o have the habit of living in association with human settlements, in hay barns etc. in the vicinity of saratov on the east bank of the vulga river both species were caught in two haystacks in early spring (belanin c t al. 1973, quoted by k r i l et al. 1980). in both haystacks m . epiroticus was by far the most common species, the proportions of epiroticus and arvalis being 38 : 3 and 5 6 : 2 , respectively. however, the exact ecological requirements of either species and the differences between t h e species have not yet been fully elucidated (kral e t al. 1980). t h e close association af t h e svalbard voles to human buildings has been pointed o u t by several authors (nyholm 1966; alendal 1977; bolshakov & shubnikova 1988). t h e apparent association of m . epiroticus with humans may have been important during the species' colonization and establishment in svalbard. however, it is clear that the highly viable population in the fuglefjella area occurs in natural habitats independent of human settlements. svalbard is located 657 km north of nordkapp, midway between norway and the north pole, and has never been connected by a landbridge with fennoscandia o r any other part of the eurasian continent. voles cannot possibly have survived a fortuitous transport on ice or on a the ‘common vole’ in svalbard 289 floating log because of the long distances involved. thus, the voles must have been brought t o svalbard by man. ( w e also exclude t h e possibility that voles were introduced secretly t o svalbard by scientists as part of an ecological experiment.) both arualis and epiroticus exist in the leningrad region (pavlovsk, volosovo and volchov districts), but in t h e areas closest to the coast (leningrad and the lomonosov district) only epiroticus was found (mejer et al. 1972; malygin & orlov 1974; k r i l e t al. 1980). however, the recent discovery of m . arualis in southeastern finland (fredga et al. unpublished) indicatesthat bothspeciesrnay occursyrnpatrically along t h e easternmost coasts of the gulf of finland. however, m. epiroricus is by far the most common species in finland a n 3 adjacent parts of t h e ussr. hence, fixiand, western ussr and balkan are the only areas where m . epiroticus exists near water and harbours. w e a r e not aware of any transportations from the eastern mediterranean (yugoslavia o r greece) or from the black sea (ussr, rumania or bulgaria) to svalbard. finland has not been involved in any industrial o r agricultural activities in svalbard. thus, we find it unlikely that the voles in svalbard originate from the balkan peninsula or finland but from the western parts of the ussr, bordering the gulf of finland. t h e russians have exploited coal mines in grumantbyen since 1920 (hoe1 1966) and at coles bay since 1938 (bolshakov & shubnikova 1988). horses were used for transportation and hay must have been brought there for their winter survival. w e conclude that the voies were introduced together with hay by russian ships from leningrad (or nearby harbours) in the period 1920-1960, and thus originate from the vicinity of leningrad. prof. charles elton visited svalbard in 1921, 1923 and 1924 as a member of the oxford expeditions to svalbard. ‘i feel certain they [the voles] were not introduced by 1924 the last time i went there! i would have been told’ (charles elton, in a letter to k.f.). further studies of dna may tell us whether voles were introduced to svalbard more than once, and may also support t h e hypothesis about their origin put forward here. we cannot exclude the possibility that m. arvalis also has been introduced. but so far, the only vole species that has been proven t o exist in svalbard is m . epiroticus. acknowledgements. this study was supported financially by the swedish natural science research council, the norwcgian polar research institute, the ‘fondation franco-norvegiennc pour la recherche scicntifique et techniquc ct le d&aoppcmcnt industriel’ (ffn) and the norwcgian research council for scicnce and thc humanities (navf). references alendal, e . 1977: sdrlig markmus har fatt fotfcste p i svalbard. fauna 30, b l l . belnntn, a . n . , vcnig, l. l.. l a r k , n . i . 9r sonin. k . a . 1973: characteristics of tlic karyotypes of the common volc (microtus drualis pall.) froin thc povoliie. fzzid. popu/. ekol. iw., sarutoo i , 6 6 7 2 . bolshakov, v . n. & shuhnikova, 8 . n. 1988: common volc microtus uroalis (rodlntia, muridae) on spitshergcn archipelago. 2001. zhurn. 67, 3or-310 (in russian). frcdga, k. 1987: chromos:ime preparations i n the ficld from mammals long after dzath. stain techno/. 62, 167-171. gamperl, r. 1982: die chromoromcn v a n microrus uroalis (rodcntia, micro!inac). z . siiugelierkundc 47, 35h-363. h o d , a. 1966: sun1bui.d i . sverrc kildah!s b o k t r y k k e i i , oslo. honacki. j . h . , kinman, k . e. & koeppl, j . mi. (eds.) 1982: murnmol species of the w x l d c a l u x o n w i i c and geographic rcference. allen press and the association of systematic co!lections, lawrence. kansas, u . s . a krbi, b., bclanin, a . n., ziina, j . , malygin, v. m.. gajccnko, v. a . & orlov, v. n . 1980: distribution of microtus aruulis and m . epirolicus. actu sc. net. brno 14, 1-30, kral, 6 . & l.yapunova, e. a . 1975: karyotypes of 46 chromosome microtm arudi,s (micratidac. rodentia). zool. listy 2 4 , 1-11, malygin, v. m. 1983: systcmurics o f i h ~ c ; r n r u n uolc. nauka, moscow. 208 i)p (in h s s i a n ) . malygin, v. m. & orlov, v . n . 1974: a : x of 4 species of voles (aupcrspccics microtus aruulis) by karyologicai data. zool. zhurn. 53, 610-622 (in russian). malygin, v . m. 9, yatsenko, v. n. 1986: taxonomic nomcnclaturc of sibling species of the common volc (rodenria, cricctidae). z d . zhurn. 35, 579-591 (in russian). mejcr, m. n . , moroz, j . m . , orlov, v. n . b scholl, e. d. 1973: zwillingsartcn der feldmaus, mzcrotus n r u d b (pallah). mitt. zool. mlls. berlin 49, 387-402. mcjcr, m . n., orlov, v. n. & scholl, e. d. 1372: on thc nomenclature of 46and 54-chromosome voles of ?he type microrrrs orua1i.s (pall.) (rodentia, cricetidae). zoo/. zkurn. 51, 157-161 (in russian). mejer, m . n., radjabli, s. j . . bulatova, n . s . & golenischcv, f. n . 1985: karyotypical peculiarities and probable relations of common volesof the group ‘uroulis’ (rodentia, cricetidac, microrus). 2001. zhurn. 6 4 , 417-428 (in russian). niethammer, j . & krdpp, f. 1982: microtw aroalis (pallas, 1779) feldmaus. pp. 284-318 in niethammer, j . & krdpp, f. (eds.): hundbuch der saugetiere europas 2 ( 1 ) . rodentiu: 11. akademische verlagsgesellschaft. wiesbaden. nyholm. e . s . 1966: observations on some birds and mammals of spitsbergen. ann. 2001. fenn. 3, 173175. ride, w. d. l., sabrosky, c. w., bernardi, g . & melville, r. v. (eds.) 1985: international code of zoologicul nomenclature (3rdedition). internationaltrust for zoological 290 k. fredga et al. nomenclature in association with british museum (natural history), london, and univ. of california press, berkeley and los angeles. ruzic, a , , petrov, b . & zivkovic, s. 1975: on the species independence of the 54-chromosome vole microfurs epiroticus ondrias 1966 (mammalia, rodentia), its distribution, ecology and importance as a pest in the west part of balkan peninsula. 1. sci. agri. res. beograd 28, 153-160. sakiyan, s. m . , kulbakina, n . a , , serov, 0. l., mejer, m. n . & zharkikh, a . 1984: assessment of the degree of genetic divergcnce of the twin species of the common vole microfurs urvalis and microtus subaroulis (rodentia). genetika 20, 13651372. sumner, a . t. 1972: a simple technique for demonstrating centromeric heterochromatin. e x p . cell res. 75, 304306. vorontsov, n. n . , lyapunova, e. a . , belyanin, a . n., kral, b . , frisman, l. v., ivnitsky, s . b. & yanina, i. y . 1984: comparative genetic methods of diagnostics and estimation of the degree of divergence for the sibling species of common voles microtus aroalis and m. epiroticw. zool. zhurn. 63, 1555-1566 (in russian). wang, h. c. & fedoroff, s. 1972: banding in human chromosomes treated with trypsin. nature new b i d . 235. zima, j . & kril, b. 1984: karyotypcs of european mammals 52-53. 11. acfu sc. nar. brtio 18, 1-62. volcanic passive continental margin beneath maitri station in central dml, east antarctica: constraints from crustal shear velocity through receiver function modelling research article volcanic passive continental margin beneath maitri station in central dml, east antarctica: constraints from crustal shear velocity through receiver function modelling sandeep gupta , nagaraju kanna & a. akilan council of scientific and industrial research, national geophysical research institute, hyderabad, india abstract dronning maud land (dml) in east antarctica is considered to be a key area for the reconstruction of the gondwana supercontinent. we investigate the crustal shear wave velocity (vs) model beneath the maitri station, situated in the central dml of east antarctica, through receiver function modelling. the analysis shows an average crustal thickness of 38.50 ± 0.5 km and a vp/vs ratio of 1.784 ± 0.002. the obtained vs structure suggests that the topmost ca. 2.5 km of the crust contains ice and sediments with low vs (1.5–2.0 km/s). this layer is underlain by a thick (ca. 12.5 km) layer of vs = 2.25–2.6 km/s, suggestive of an extrusive igneous rock (rhyolite) at this depth range. between 16 and 28 km depth, the vs increases from 2.9 to 3.4 km/s. in the lower crust, a 7 km thick layer of vs = 3.9 km/s is followed by 6 km thick underplated layer (vs = 4.1 km/s) at the crust–mantle boundary. the uppermost mantle vs is ca. 4.3 km/s. with the observation of underplated material in the lowermost crust, extrusive volcanic rocks in the upper crust, seaward dipping reflectors in the surrounding and a general paucity of seismicity, we believe the crust beneath the maitri station represents a volcanic passive continental margin. we also believe that after its origin in the precambrian and during its subsequent evolution it might have been affected by the post-precambrian tectono-thermal event(s) responsible for the gondwana supercontinent break-up. keywords crustal shear velocity; volcanic passive margin; maitri station; dronning maud land; underplated lower crust; neighbourhood algorithm abbreviations csir-ngri: council of scientific and industrial research – national geophysical research institute; dml: dronning maud land; rf: receiver function introduction the antarctic plate has a unique tectonic setting. it is surrounded almost completely by divergent margins, with a very small amount of convergent or transformed margins. the antarctic continent is roughly divided into two large tectonic provinces: east antarctica and west antarctica, divided by the transantarctic mountains (fig. 1a). west antarctica is a chain of many islands beneath the ice sheet of the cenozoic era attributed to active volcanoes (kaminuma 2006). east antarctica is considered as a stable, cratonic block with a precambrian basement. limited geological samples are available from this region covered by thick ice, but several geophysical studies have revealed the average crustal and upper mantle structure in east antarctica to define its geo-tectonics. the average crustal thickness in east antarctica is reported to be ca. 40 km (e.g., malaimani et al. 2008; bayer et al. 2009; baranov & morelli 2013). with a ca. 20 km thick upper crust and a slightly higher-thannormal seismic velocity, bentley (1983) reported a typical continental crust for east antarctica. surface wave studies found craton-like velocities in east antarctica (bentley 1991; ritzwoller et al. 2001). a deep electrical conductivity structure under schirmacher oasis in central dml showed highly resistive (8000–10 000 ohm m) upper crust followed by lesser resistive (500–600 ohm m) lower crust; and the results were interpreted that the schirmacher oasis to be a stable cratonic platform (murthy et al. 2013). another magnetotelluric study in the schirmacher oasis (fig. 1) revealed that the crust had a higher resistive (103 to ca. 104 ohm m) upper layer underlain by a moderately resistive (100–300 ohm m) layer and the moho was at 32–38 km (abdul azeez et al. 2015). a regional gravity study showed that the moho depth was ca. 32 km below the schirmacher oasis (verma et al. 1994). the heat flow in much of east antarctica was reported to be ca. 50 mw m−2 or more (siegert 2000) and the observed thermal anomalies were related to the mantle plume (hole & lemasurier 1994). the magset data (ritzwoller & bentley 1983) showed that the regional negative magnetic anomaly in central dml could be indicative of an intensive thermal reactivation of dml due to late precambrian tectono-thermal activity, which might have caused an up-doming of the curie isotherm contact sandeep gupta sandeepgupta@ngri.res.in council of scientific and industrial research, national geophysical research institute, uppal road, hyderabad 500007, india the supplementary material for this article can be accessed here. polar research, 2017 vol. 36, 1332947 https://doi.org/10.1080/17518369.2017.1332947 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0002-9961-9844 http://orcid.org/0000-0002-9919-0574 https://doi.org/10.1080/17518369.2017.1332947 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1332947&domain=pdf and might thus have reduced the thickness of the magnetically active crust (bormann et al. 1986). the antarctic digital magnetic anomaly project compilation provided important constraints on the break-up processes and igneous activity related to the formation of the passive margin of east antarctica (golynsky et al. 2013). east antarctica has not experienced any significant tectonic deformation and its lithosphere may still be preserving the crustal and upper mantle characteristics inherited during the evolution of the gondwana supercontinent. moreover, dml is composed of different crustal blocks of varying ages from archean to early paleozoic and is considered to be a key area for the reconstruction of the gondwana supercontinent, containing continental fragments of both east and west gondwana (riedel et al. 2013; mieth & jokat 2014). using limited direct geological sampling and the average crust–upper mantle structure from geophysical studies of this critically located region, various tectonic models were proposed for the history and geometry of the gondwana supercontinent break-up (e.g., mieth & jokat 2014 and references therein). a detailed study of the crustal structure and the nature of intracrustal layers can be very useful for understanding the mechanism responsible for the breakup of the gondwana supercontinent and also the dynamics of plate motions. therefore, in this study we investigated in detail the crustal shear wave velocity (vs) structure beneath the maitri broadband seismic station (70.76ºs; 11.73ºe) in east antarctica through modelling of teleseismic rf and studied the possible role of this region in the gondwana geodynamics. the maitri broadband seismic station is in the indian antarctica base station located in schirmacher oasis, near the princess astrid coast, east antarctica (fig. 1b). schirmacher oasis is a coastal nunatak in the central dml. the exposed rocks in central dml indicate that it is probably related to a major tectono-thermal event at ca. 650–490 mya—the pan-african event (mieth & jokat 2014). a sequence of seaward dipping reflectors, associated with middle to late jurassic volcanism was reported off central dml (hinz & krause 1982). jacobs et al. (2003) proposed an asthenospheric upwelling, followed by the mantle delamination of the orogenic root for the central dml. data we used data recorded by a permanent broadband seismic station at maitri during 2006–08, operated by the csir-ngri (fig. 1b). the station configuration includes a cmg 3esp sensor with a flat velocity response between 100 s and 50 hz and a reftek 72a 121–03 data logger. data was continuously recorded at 50 samples/s and gps time was logged. we computed rfs using the iterative time domain deconvolution approach (ligorria & ammon 1999) from good signal-to-noise ratio earthquakes of magnitude (mb) > 5.5 in the epicentral distance 30–95° (fig. 1c). to minimize the influence of the costal noise on the rfs, a two-pole high pass filter with a corner frequency of 0.02 hz was applied to the waveforms. rfs were calculated using gaussian width corresponding to low pass filters with corner frequencies of 2.4, 1.25, 0.7, 0.5 hz. for further analysis, we used only the rfs with variance reduction cut-off above 80% and the direct p-wave within one second of the zero time on the deconvolved trace. at higher frequencies, the rfs were noisy while at lower frequency these were smoothed out. as we aimed at mapping the crust–mantle boundary along with other intra-crustal layers, we preferred to use the rf with gaussian width 1.6 for further analysis. all the calculated rfs with respect to back-azimuth (left axis) and epicentral distance (right axis) are presented in supplementary figure 1. (a) topography map of antarctica showing the study region (trapezoid-shaped box) and the major tectonic units: east antarctica, west antarctica and the transantarctic mountains. (b) simplified tectonic map of the study region (after jokat et al. 2004). the triangle represents the maitri seismic station. (c) epicentre distributions of 29 teleseismic earthquakes (red stars) used to calculate rfs. 2 s. gupta et al. fig. s1. the moho converted p-to-s (ps) phase was observed at ca. 5 s with its multiples at ca. 16 s and ca. 21 s. receiver function modelling in order to minimize the effects of noise and aid in visually enhancing coherent arrival, rfs with good signal-to-noise ratio were stacked in a narrow epicentral distance and back-azimuth bins. figure 2a shows the six individual rfs for back-azimuth 83–95° and epicentre distance 85–90°, which were stacked (fig. 2a) for further analysis and determination of the velocity structure beneath the study region. moho depth and vp/vs ratio estimation to obtain the moho depth (h) and average vp/vs ratio, we used the h–vp/vs stacking technique of zhu and kanamori (2000), which is a well-established technique and exploits the fact that the arrival times of the specific moho converted phase and multiples appearing on rfs are determined by known functions of moho depth (h), vp/vs ratio and average crustal p-wave velocity (vp). we used an average vp of 6.25 km/s. h and vp/vs ratio were allowed to vary from 20 to 50 km (with 0.05 km increment) and 1.6– 1.9 (with 0.002 increment), respectively. in the computation, based on amplitudes of ps, pppms and ppsms+pspms phases, we assigned different weights of 0.6, 0.3 and 0.1, respectively. we followed the same procedure with vp variations at ±0.1 km/s to constrain h and vp/vs ratios. figure 2b shows the result from the h–vp/vs grid search technique and the result is discussed later. shear wave velocity mapping we mapped the vs variation with depth beneath the maitri seismic station from the stacked rf (fig. 2a) following the nonlinear neighbourhood algorithm proposed by sambridge (1999) and as in gupta et al. (2010). the method assumes a one-dimensional isotropic velocity model. it is a multi-dimensional parameter space search algorithm that only needs to solve the forward problem and does not require the computing of partial derivatives of the rfs. this method uses an ensemble-based monte carlo search technique to find the set of velocity models which best satisfy the objective function. we used, as our objective function, a scaled l2-norm of the difference between the theoretical and the observed rf. figure 2. (a) plot showing the stacked rfs used to infer the crustal structure beneath the maitri station. below this are the six rfs used for stacking. (b) plot showing the results of the h–vp/vs stacking technique (zhu & kanamori 2000) for the stacked rfs shown in (a). the black dot within the contour represents the maximum amplitude; the corresponding h and vp/vs values are shown in the rectangular box. (c) one-dimensional shear velocity models obtained from the neighbourhood algorithm inversion (sambridge 1999). details are given in the text. (d) simplified shear velocity model (red line) along with different layers, shown along with the final inversion model (black line). details are given in the text. polar research 3 in this study, we used a time-window of 30 s and a 24-dimensional parameter space, defined by six flat layers, each with four parameters (layer thickness, vs at the top and bottom of each layer, and vp/vs ratio). the two vs parameters in each layer allow the definition of a velocity gradient for that layer, which allows the representation of a large number of potential velocity– depth distributions. very loose a priori constraints were placed on the minimum vs and maximum vs, the layer thicknesses, as well as vp/vs. the model parameterization is shown in supplementary table s1. each inversion run involved 200 iterations, generating 20 100 velocity models. the stability of the inversion solutions was tested using a large range of initial random seeds, incidence angles, and velocity model parameterizations. in fig. 2c, the best fit vs model (solid black line) along with all other models (solid grey lines) that fit the rfs are also displayed. the green region depicts the best 1000 velocity models and the red solid line represents an average of these 1000 models. the vp/vs ratio variation for the best model (black line) and for an average model (red line) is shown in the left side of fig. 2c. the one-dimensional velocity model obtained by the inversion process is able to model the dominant phases in the rf. the calculated rf (red line) and the observed stacked rf (blue line) with ±1σ bounds (black lines) are shown in the bottom of fig. 2c. figure 2d shows the simplified model (red line) of the final model (black line) from inversion and matching of the calculated rf (red line). the observed rf is shown in the bottom of fig. 2d. figure s2 shows the corresponding moho piercing point and the back-azimuth direction which were imaged by this velocity model. results and discussion beneath maitri station, the moho depth is 38.50 ± 0.5 km and the average vp/vs is 1.784 ± 0.002 (fig. 2b). the moho depth is in agreement with earlier estimates for this region, using rf analysis (malaimani et al. 2008), rf analysis and modelling of a seismic refraction profile (bayer et al. 2009), and a compilation of various available data from seismic reflection/refraction and rfs (baranov & morelli 2013). the higher vp/vs ratio suggests an intermediate-to-mafic crust beneath this region. the vs model (red colour line in fig. 2d) indicates that the top ca. 1.0 km thick layer of ice with low vs (ca. 1.4 km/s) is underlain by a thin (ca. 1.5 km) layer of sediments (vs ca. 1.9–2.0 km/s). these layers are underlain by a ca. 12.5 km thick layer of vs = 2.25–2.6 km/s. in this depth range, equivalent to ca. 300–400 mpa pressure, a layer with vs = 2.25–2.6 km/s can be indicative of rhyolite (an extrusive igneous) rock (christensen & stanley 2003). at a depth of 16–28 km we observe that vs increases from 2.9 to 3.4 km/s. at a depth of 28 km, we find a ca. 7 km thick layer of vs = 3.9 km/s, representing lower crustal mafic material. this layer is followed by a 6 km layer of vs = 4.1 km/s and another layer of vs = 4.3 km/s below. we believe that the layer with vs = 4.3 km/s represents the upper mantle, as reported by earlier studies (e.g., ritzwoller et al. 2001; bayer et al. 2009). it is interesting to observe a transitional layer (vs = 4.1 km/s) between lower crust (vs = 3.9 km/s) and the uppermost mantle (vs = 4.3 km/s). similar observations have also been reported from many continental margins in the world (e.g., thybo & artemieva 2013 and references within). therefore, we think that this layer is evidence of underplated material in the lowermost crust and points to the presence of a continental margin beneath the study region. the apatite-fission-track data and the high-elevation margin morphology study of central dml also suggest a typical passive nature for this region (meier 1999). by combining our result with available knowledge from this region (the presence of underplated material in the lowermost crust, extrusive rocks (rhyolite) in the upper crust, seaward dipping reflectors (hinz & krause 1982) and a lack of seismicity (kaminuma 2006), we suggest that the crustal structure below the maitri station in the schirmacher oasis represents a volcanic passive continental margin rather than a typical continental crust. this view also gets support from the crustal seismic velocity structure along seismic refraction profile 96100 (to the north-west of our study region; fig. 1b), reporting this region as a volcanic continental margin (jokat et al. 2004), as well as many other studies (e.g., geoffroy 2005, and references therein). further, regarding the possible mechanism responsible for the obtained crustal structure beneath central dml we speculate that the crust in this region was probably formed during the precambrian. during its evolution with time it was affected by postprecambrian tectono-thermal event(s) (e.g., the panafrican) and/or by the karoo–maud plume. the latter also affected southern africa and the western part of east antarctica through its penetration into the upper lithosphere at about 180 mya and is considered to be one of the main factors for the break-up of gondwana supercontinent (sushchevskaya et al. 2009). conclusion to study the role of dml, east antarctica in the reconstruction of the gondwana supercontinent, we investigated the crustal vs structure beneath the maitri seismic station situated in the schirmacher oasis, central dml. through analysis and modelling of the teleseismic rfs calculated at the seismic station, the vs structure suggests 4 s. gupta et al. that the uppermost 2.5 km consist of ice and sediments (vs = 1.5–2.0 km/s) and are underlain by 12.5 km of extrusive igneous rock (rhyolite, vs = 2.25–2.6 km/s). between 16 and 28 km depth, vs gradually increases from 2.9 to 3.4 km/s. in the lower crust, a ca. 7 km thick layer of vs = 3.9 km/s is followed by 6 km thick underplated layer (vs = 4.1 km/s) at the crust–mantle boundary. the moho is at ca. 40 km and the uppermost mantle vs is ca. 4.3 km/s. the presence of underplated material in the lowermost crust, extrusive volcanic rocks (rhyolite) in the upper crust, seaward dipping reflectors in the surrounding area and the general paucity of seismicity suggest that the crust beneath the maitri station is a volcanic passive continental margin and not a typical cratonic continental crust. combing our results with other studies in this region, we also believe that after its formation in the precambrian and during its subsequent evolution, it was affected by the post-precambrian tectono-thermal event(s) responsible for the break-up of the gondwana supercontinent. acknowledgements the data used in this study are part of project ilp-0301-28 (vkg/jck). we thank prof. m. sambridge for providing neighbourhood algorithm inversion code used in this study. sg acknowledges support from csir-ngri projects mlp-6505-28 (skg) and index. the manuscript has been benefited immensely from the constructive comments by two anonymous reviewers and section editor robert spielhagen. disclosure statement no potential conflict of interest was reported by the authors. orcid sandeep gupta http://orcid.org/0000-0002-9961-9844 nagaraju kanna http://orcid.org/0000-0002-9919-0574 references abdul azeez k.k., prabhakar e rao s., gupta a.k., basava s. & harinarayana t. 2015. magnetotelluric study across the schirmacher oasis of central dronning maud land, east antarctica: electrical characteristics of the east african–antarctic orogen as a possible aid to link gondwana fragments. paper presented at the xii international symposium on antarctic earth sciences, 13–17 july, goa, india. baranov a. & morelli a. 2013. the moho depth map of the antarctica region. tectonophysics 609, 299–313. bayer b., geissler w.h., eckstaller a. & jokat w. 2009. seismic imaging of the crust beneath dronning maud land, east antarctica. geophysical journal international 178, 860–876. bentley c. 1983. crustal structure of antarctica from geophysical evidence—a review. in r.l. oliver et al. (eds.): antarctic earth sciences. pp. 491–497. canberra: australian academy of science. bentley c.r. 1991. configuration and structure of the subglacial crust. in r.j. tingey (ed.): the geology of antarctica. pp. 335–364. oxford: oxford science publications. bormann p., bankwitz p., bankwitz e., damm v., hurtig e., kämpf h., menning m., paech h.-j., schäfer u. & stackebrandt w. 1986. structure and development of the passive continental margin across the princess astrid coast, east antarctica. journal of geodynamics 6, 347–373. christensen n.i. & stanley d. 2003. seismic velocities and densities of rocks. in w. lee et al. (eds.): international handbook of earthquake and engineering seismology. pp. 1587–1594. amsterdam: academic press. geoffroy l. 2005. volcanic passive margins. comptes rendus geoscience 337, 1395–1408. golynsky a.v., ivanov s.v., kazankov a.j., jokat w., masolov v.n., von frese r.r.b. & the admap working group. 2013. new continental margin magnetic anomalies of east antarctica. tectonophysics 585, 172–184. gupta s., mishra s. & rai s.s. 2010. magmatic underplating of crust beneath the laccadive island, nw indian ocean. geophysical journal international 183, 536–542. hinz k. & krause w. 1982. the continental margin of queen maud land/antarctica: seismic sequences, structural elements and geological development. geologische jahrbuch e23, 17–41. hole m.j. & lemasurier w.e. 1994. tectonic controls on the geochemical composition of cenozoic, mafic alkaline volcanic rocks from west antarctica. contributions to mineralogy and petrology 117, 187–202. jacobs j., bauer w. & fanning c.m. 2003. late neoproterozoic/early palaeozoic events in central dronning maud land and significance for the southern extension of the east african orogen into east antarctica. precambrian research 126, 27–53. jokat w., ritzmann o., reichert c. & hinz k. 2004. deep crustal structure of the continental margin off the explora escarpment and in the lazarev sea, east antarctica. marine geophysical researches 25, 283–304. kaminuma k. 2006. seismicity in the antarctic and surrounding ocean. journal of indian geophysical union 10, 15–24. ligorria j.p. & ammon c.j. 1999. iterative deconvolution and receiver function estimation. bulletin of seismological society of america 89, 1395–1400. malaimani e.c., ravi kumar n., padhy s., rao s.v.r.r., chander g.b., srinivas g.s. & akilan a. 2008. continuous monitoring of seismicity by indian permanent seismological observatory at maitri. indian journal of marine sciences 37, 396–403. meier s. 1999. paleozoic and mesozoic tectono-thermal history of central dronning maud land, east antarctica – evidence from fission track thermochronology. berichte zur polarforschung 337. bremerhaven: alfred wegener institute. mieth m. & jokat w. 2014. new aeromagnetic view of the geological fabric of southern dronning maud land and coats land, east antarctica. gondwana research 25, 358–367. murthy d.n., veeraswamy k., harinarayana t., singh u.k. & santosh m. 2013. electrical structure beneath schirmacher oasis, east antarctica: a magnetotelluric study. polar research 32, 17309. polar research 5 riedel s., jacobs j. & jokat w. 2013. interpretation of new regional aeromagnetic data over dronning maud land (east antarctica). tectonophysics 585, 161–171. ritzwoller m.h. & bentley c.r. 1983. magnetic anomalies over antarctica measured from magsat. in r.l. oliver et al. (eds.): antarctic earth sciences. pp. 504–507. canberra: australian academy of science. ritzwoller m.h., shapiro n.m., anatoli l., levshin a.l., garrett m. & leahy g.m. 2001. crustal and upper mantle structure beneath antarctica and surrounding oceans. journal of geophysical research – solid earth 106, 30645–30670. sambridge m. 1999. geophysical inversion with a neighbourhood algorithm-i searching a parameter space. geophysical journal international 138, 479–494. siegert m.j. 2000. antarctic subglacial lakes. earth-science reviews 50, 29–50. sushchevskaya n.m., belyatsky b.v., leichenkov g.l. & laiba a.a. 2009. evolution of the karoo–maud mantle plume in antarctica and its influence on the magmatism of the early stages of indian ocean opening. geochemistry international 47, 1–17. thybo h. & artemieva i.m. 2013. moho and magmatic underplating in continental lithosphere. tectonophysics 609, 605–619. verma s.k., vyaghreswara rao m.b.s. & gopal b.v. 1994. gravity survey (helicopter supported) between schirmacher oasis and wohlthat mountains, dronning maud land, antarctica. in: ninth indian expedition to antarctica, scientific report, 1994. technical publication 6. pp. 209–217. new delhi: department of ocean development. zhu l. & kanamori h. 2000. moho depth variation in southern california from teleseismic receiver functions. journal of geophysical research – solid earth 105, 2969–2980. 6 s. gupta et al. abstract introduction data receiver function modelling moho depth and vp/vs ratio estimation shear wave velocity mapping results and discussion conclusion acknowledgements disclosure statement references grenvillian single-grain zircon pb age of a granitic rock from the southern island of hesteskoholmen, liefdefjorden, northwestern spitsbergen, svalbard yoshihide ohta and aleksandr n. larionov ohta. y. & larionov, a. n. 1998: grenvillian single-grain zircon ph age of a granitic rock from the southern island of hesteskoholmen, liefdefjorden, northwestern spitsbergen, svalhard. polar resenrck 17(2), 147-154. a n-s trending, narrow zone of crystalline basement occurs from biscayarhalv@ya to hultedahlfonna in northwestern spitsbergen and is composed of various metasedimentary and igneous rocks, including granites. previous isotopic age determinations on these rocks are by the k-ar. rb-sr, '"ad9ar and conventional zircon u-pb method and yielded the caledonian and grenvillian ages. the single-grain zircon pb evaporation method has recently been applied to solve complex problems and this is the first report by the method. a granitic rock. syntectonically intruded into the phyllitic metasediments of the biscayarhuken formation. which is the uppermost lithotectonic unit in the metamorphic rocks of the zone, was dated on four zircon grains, yielding a narrow age range from 955 f 4 to 968 + 9 ma, 961 f 4 ma in average. this age of ca. 960 ma is considered to be the age of intrusion, based on the occurrence and zircon morphology, which is roughly simultaneous with the formation of the phyllitic cleavages of the surrounding metasediments. the data obtained imply that the caledonian events did not reset the ph isotope system of zircon and major metamorphism occurred during the grenvillian time in the biscayarhuken fomiation, accordingly, the protolith age of the metasediinents is mesoproterozoic. y . oatu. norsk polnr-in.stitritt, p . 0. box 5072 m(ijorstuu, n-0301 oslo, norway; a n . lcrrionov, luborirtoriet fijr isotopgeologi, naturhistorisku riksinuseet, box 50 007, s-104 05 stockholni, sweden. introduction the precambrian event history of the crystalline basement of northwestern spitsbergen has earlier been studied based on field observations and petrographicallpetrological approaches. however, the time scale for the sequence of geological events has been weakly understood, except for the k-ar and rb-sr ages of caledonian thermal events (gayer et al. 1966; hjelle 1979; ravich 1979). isotopic age determination project to study pre-caledonian history of the rocks was started in 1985, and several results have been published by peucat et al. (1989), dallmeyer et al. (1990a) and balasov et al. (1996), mainly by the conventional u-pb and 40ar/39ar methods (fig. 1 ). the results suggested the presence of older zircons, possibly back to archean time. therefore, the single-grain zircon pb evaporation method has been applied since 1996. this is the first report of ages obtained by this method from northwestern spitsbergen. geological outline pre-devonian crystalline basement rocks are widely exposed in the north-western part of spitsbergen, i.e. the area north of kongsfjorden and west of woodfjorden (gee & hjelle 1966: hjelle 1979; gjelsvik 1979; hjelle tk lauritzen 1982). the area is separated by the hi-s trending raudfjorden fault (rf: fig. 1 ) . to the west of the fault, a complex of schist-gneiss-migmatites occurs, while devonian old red sandstones unconformably overlie the crystalline rocks in the east of the rf (gee & moody-stuart 1966). the latter crystalline rock area is here referred to as the biscayarhalvfiya-holtedahlfonna zone (b-h zone) (the place name biskayerhalvaya has been changed to biscayarhalvoya in recent maps; therefore, the geological terms including this place name are changed in this paper according to the recommendation of norwegian strati graphic committee). 148 y. ohta & a . n . larionov albert i land a devonian and younger sediments hornernantoppen granite 0 schists, gneisses, migrnatites, marbles bf: breibogen fault h: hornernantoppen hf: hannabreen fault t: texas bar hut rf: raudfjorden fault n-b-h: northern byscayarhalveya-holtedalfonna subzone s-b-h: southern byscayarhalveya-holtedalfonna subzone f i g . 1. geological map of northwestern spitsbergen, with previously published isotopic ages. the ages obtained from biscayarhalveya are not shown, but mentioned in the text. the b-h zone, a narrow n-s trending zone of ca. 10-15 km width and ca. 100 km in length, consists of lithologically different metamorphic rocks in the north (n-b-h subzone) and south (s b-h subzone). the two subzones are separated by an oblique fault, the hannabreen fault (hf; gee & moody-stuart 1966; gjelsvik 1979), extending faults: bf: breibogen fault; hf: hannabreen fault place names from north to south: bh: biscayarhuken ab: albertbreen rt: rivieratoppen hb: hannabreen rv: richardvatnet sk: siktefjellet an: andreebreen tx: texas bar hut fig. 2. geological map of biscayarhalveya and hesteskohol men (inserted map; the location is shown in the main map). the location of dated sample is shown by an arrow in the inserted map. from rivieratoppen in the north to hannabreen in the south (fig. 2 ) . the s-b-h subzone has a simple antiform structure with thick pelitic schists, gneisses and marbles on both western and eastern limbs and migmatites and granites along the crestal area. the metamorphic rocks, excluding the migma grerivillian single-grain zircon pb age of n granitic rock 149 tites, show distinct brittle thrust duplex structures with an easterly vergence on both the northern and southern sides of liefdefjorden. these rocks are separated from the devonian sediments by steep faults on both the eastern and western sides and locally by an unconformity in the west. the n-b-h subzone is also a horst, but more complex faults occur within the subzone. the metamorphic rocks show large scale thrust duplex structures, verging wsw. the metamorphic rocks have been grouped into three lithotectonic units, the richarddalen group, montblanc and biscayar huken formations (gee 1966; gee & hjelle 1966; dallmeyer et al. 1990a), in ascending order and are correlated with the three-fold divisions of caledonised metasediments in the schist-gneiss migmatite area to the west of the rf. the biscayarhuken formation is bounded by moderately east-dipping reverse faults to the amphibolite facies gneisses of the montblanc formation to the west (fig. 2). it occupies the eastern half of the n-b-h subzone and consists mainly of phyllitic metasediments derived from psammo-pelitic clastic sediments, including quart zites, and a few marble layers. the exposures of these rocks are interrupted by the sedimentary cover of the siktefjellet group at siktefjellet and reappear along the northern coast of liefdefjor den. the southern island of hesteskoholmen in front of hannabreen is composed of phyllitic metasedi ments, quartzite, similar to those of the northern coast of liefdefjorden, and some interlayered amphibolites. the granitic rock dated in this work occurs in the phyllitic metasediments. two other islands of hesteskoholmen and a small sunken rock, ca. 100 m from the western coast of the bay are comprised of the devonian conglomerates, while the exposures along the western coast of the bay and in the southwest of the alluvial fan of hannabreen are strongly sheared marbles showing an e-verging duplex extending ca. 4 k m to the west. these marbles are continuous to that of the s-b-h subzone across liefdefjorden to the south, where marbles and pelitic schists/gneisses show similar brittle duplex structures. thus, the bound ary between the sand n-b-h subzones, the hannabreen fault, should be located between the small sunken rock and the coastal exposures west of the bay. the phyllitic metasediments are unconformably overlain by the basal conglomerates of the siktefjellet group on the northern slope of siktefjellet. these are again overlain unconform ably by the basal conglomerates of the old red sandstones, the wulffberget formation (murasov & mokin 1976) in the eastern part of andrce breen. the exact age of the siktefjellet group is unknown but should be the latest silurian andlor earliest devonian. previous age determinations gayer et al. (1966) reported eleven k-ar ages from the northern part of biscayarhalvoya. meta eclogites and amphibolites from the richarddalen group and the montblanc formation yielded ages from ca. 530 to 1,940ma. ages of 431 and 382ma were obtained from a biotite and a hornblende, respectively, from the schists of the biscayarhuken formation. the localities were shown in figure 2 of dallmeyer et al. (1990a). ar/39ar datings were canied out by dall meyer et al. (1990a) on the rocks of the montblanc formation and the richarddalen group. the hornblendes of the richarddalen group gave ages of ca. 505-538 ma, while muscovites from the same group yielded ages of ca. 431 and 480 ma. ages of 442 and 439 ma were obtained from the hornblendes of the montblanc formation. rb-sr age determinations were also made by the same authors, and the muscovite-whole rock systems of both the richarddalen group and montblanc formation gave similar age ranges of ca. 420-430 ma, while biotite-whole rock systems show age range of 402-413 ma. the difference in the ages between the two systems reflects the closure temperature of the systems, ca. 500°c for muscovite and ca. 300°c for biotite (jager 1979). conventional u-pb age determinations and sr and nd isotope analyses were canied out by peucat et al. (1989), using the samples from the richarddalen group. a meta-porphyritic granite, mostly changed into augen gneisses with dis tinctive amount of garnet, yielded a lower intercept age of 965ma and an upper intercept age of 3.234ga, the latter with a large error. a corona gabbro showed an upper intercept age of 955 ma. an eclogitic rock (gee 1966) and a felsic neozome in a gneiss yielded zircon ages of 620 and 661 ma, respectively. the last two ages were considered to be mixing age by peucat et al. (1989). recent works of the sphene u-pb ages and pb 40 150 y. ohta & a . n. larionov evaporation ages of single-grain zircon ages by gromet & gee (in press) argued that the ages of 620-660 is a magmatic event associated with the rifting of paleo-atlantic and that a high-grade metamorphism occurred in middle ordovician, ca. 455ma, approximately at the same time the high-pressure metamorphism was established in west-central spitsbergen (ohta et al. 1984; dallmeyer et al. 1990b). the sr initial ratios and end suggest that the ages of 965 and 955ma are crustal reworking ages. these results, together with that of dall meyer et al. (1990a) are interpreted in a way that a distinctive igneous event occurred ca. 960 ma ago, while the 3.2 ga data suggest the presence of older detritayinherited zircons. the caledonian thermal events up to ca. 500" possibly subdivided into two phases, ca. 470 and 430 ma as established in the west-central coast of spitsbergen (ohta 1992) were superposed on all metamorphic-igneous rocks of the n-b-h subzone with different metamorphic grades on the rock units separated by wnw verging thrusts. be the southernmost exposure of the biscayarhu ken formation. the dated granitic rock occurs in eight concordant/subconcordant layers each 1-3 m thick, in the sericite-chlorite phyllites on the southern coast of the southern island (fig. 3). the rock is strongly sheared by brittle fractures emphasised by chlorite, showing spaced clea vages. large feldspar grains, up to 1 cm long, are distinct in the hand specimens. the outlines of the granitic layers locally show low angle interfinger ing with the surrounding phyllitic metasediments along the margins. this suggests slightly oblique primary boundaries, though primary contact is completely disturbed by phyllitic cleavages. the development of a cleavage in the granitic rock is distinctly weaker than in the phyllitic metasedi ments. under the microscope, a primary coarse grained mosaic of plagioclase and quartz has been granulated in an irregular network, locally showing weak preferred orientation. biotite flakes were converted into green chlorite and aggregates of vermiculite and have been locally tom off into the dated rock the dated granitic rock was collected on the southern shore of the southern island of heste skoholmen (fig. 2). a dark-coloured conglomer ate, probably belonging to the siktefjellet group, occurs at the northern tip of the island which is in contact with phyllitic metasediments by a ne striking steep fault. the phyllitic rocks are derived from sandy to shaley sediments and have strong cleavages defined by chlorite and sericite, striking nnw-sse to n-s with dips of 30 to 60"w. thin quartzite layers are interbedded in the northeast and at the southeastern to southwestern coasts, and thin schistose amphibolites occur at the northeastern and western coasts. these phyllitic metasediments with quartzites and amphibolites are very similar to those along the northern coast of liefdefjorden, immediately to the east of hesteskoholmen. the structures are also similar, though the strikes are more westerly on the northern coast. the lack of amphibolite is one of the lithological criteria of the biscayarhuken formation (gee & hjelle 1966) which has not thoroughly been mapped in the southern n-b-h subzone. however, based on the assumption of structural continuity, these rocks are considered to fig. 3. occurrence of the dated granitic rock, a photo and its sketch gr = granitic rock; ph = phyllite. grenvillian single-grain zircon pb age of a granitic rock 15 1 table 1. modal (%) and chemical compositions (wt%) of the dated granitic rock. modal composition (7o) of the dated granitic rock qt pi k-f mafics granulated part 38 49 5 8 blastoporphyritic part 27 44 22 i chemical composition (wt%, fe203 = total iron) sioz ti02 a1203 fe20; mno mgo cao nazo klo p20, h 2 0 total 74.18 0.29 12.33 2.46 0.04 0.38 1.24 4.89 2.33 0.07 1.54 99.75 small flakes showing a cleavage. large grains of k-feldspar with c-twins and local myrmekitic margins are well preserved. some large plagio clase grains show polysynthetic twins and are strongly saussuritised. small idiomorphic apatite and zircon grains occur scatteredly, and pyrite and carbonates are secondary minerals. the granu lated parts of the rock apparently have grano dioritic modal compositions and the identification of plagioclase and k-feldspar is not accurate: while the blastoporphyritic parts have quartz monzonite composition, the bulk modal composi tion ranges from granite to granodiorite (table 1). the chemical composition is a calcalkalic, peraluminous granite and has moderate kzo, i type characteristics (chappell & white 1974). the rock plots in the field of post orogenic granites in the si02-feo/fe0 + mgo and si02 a1203 diagrams of maniar & piccoli (1989) (table 1). a weaker cleavage development than that in the surrounding phyllitic rocks is con firmed by microscopic observations. the locality of these rocks is situated ca. 1 km east from the supposed position of the hanna breen fault between the n-b-h and s-b-h subzones. the overlying devonian conglomerates show different bedding directions from place to place in the two northern islands. this means that the hannabreen fault moved later than the deposition of the devonian sediments and some brittle deformation might have occurred around this area, resulting a part of the cataclastic texture of the granitic rocks. fig. 4. dated zircon grains. the occurrence and petrography of the granitic rock suggest that the rock intruded subconcor dantly along the cleavage surfaces of the phyllitic metasediments, while later brittle shearing gave the rock cataclastic, gneiss-like texture. it is considered that the intrusion occurred during or in a later time of the development of phyllitic cleavages. therefore, the age of the granitic rock is expected to define the youngest limit of the metamorphic/deformation event of the biscayar huken formation. zircons zircon grains were separated by standard techni ques, using the wilfley table, heavy liquids and the frantz isodynamic separator. the morphology and structure were examined under the optical microscope. four zircon grains, most transparent, less fractured and inclusion-free grains, were hand-picked for the single-grain isotopic analysis (fig. 4). the analysed zircon grains are non-magnetic, suband euhedral, short to moderately prismatic in outlines, with pink to light brown colours. most grains have facets of (100) and (101), with or without (1 10) and (221). grains 2 and 3 are flat in shape. the surfaces are usually smooth. ideo morphic oscillatory zoning concordant to the crystal outline is clearly seen. no discordant core has been observed. small black flakes and transparent inclusions are common. grain 1 is fractured. these characteristics of the zircon grains imply a magmatic origin. analytical notes the step-wise, single-grain zircon pb-evaporation method was applied, following standard techni ques of kober (1986; 1987). all analyses were 152 y. ohta & a. n . larionov table 2. isotopic data. abbreviations: m, moderately prismatic; s, short prismatic, ft: flat shape; p = pink, 1b = light brown, t = transparent, f = fractured, 2 = zoned, +ib = with black inclusions; +it = with transparent inclusions. biweight mean on measured ratios’ step no + number of scans ”o6pb/’o4pb i 2u% 207pb/z06pb f 2u% g r i n 1: moderat. prism., pink, transp, fract., black inclus., ?zoned 2 + 20 20000 8.0 3 + 20 32400 15.0 4 + 20 28700 18.0 5 + 20 61400 13.0 6 + 20 16900 9.0 7 + 20 44800 7.0 8 + 20 37000 14.0 weighted average grain 2: short prism., light brown, flat, transp, fract. 1 + 10 2740 9.0 3 + 20 6340 9.0 4 + 20 11900 10.0 weighted average grain 3: moderat. prism., pink, flat, transp, fract., black inclus., zoned 1 + 20 7920 10.0 2 + 10 34200 9.0 3 + 10 27200 10.0 4 + 10 6110 5.4 5 + 20 40800 6.0 6 + 20 17810 4.3 7 + 20 43600 13.0 0.07192 0.07203 0.071 18 0.07154 0.07212 0.07160 0.07139 0.07608 0.07368 0.07217 0.07277 0.07193 0.07252 0.07335 0.07187 0.07206 0.07150 0.15 0.28 0.24 0.18 0.18 0.21 0.17 0.54 0.27 0.54 0.36 0.26 0.32 0.15 0.17 0.21 0.22 weighted average grain 4 moderat. prism., pink, flat, transp, fract., transp. inclus. 1 + 20 830 36.0 0.07953 0.54 2 + 10 7640 11.0 0.07304 0.48 3 + 20 44000 25.0 0.07124 0.39 4 + 20 390000 35.0 0.07131 0.29 5 + 20 370000 46.0 0.07129 0.67 weighted average average of the four grains age, ma f 2u’ 963 f 4.0 974 i 7.0 947 + 6.0 966 i 4.0 965 f 4.5 965 i 4.5 957 i 4.0 962 i 6.5 952 i 5.5 970 i 7.0 954 i 9.5 959 f 13 956 i 6.5 973 i 6.5 985 f 6.0 958 i 5.0 972 f 3.0 965 -t 4.5 965 r 4.5 968 f 9.0 952 i 17 962 i 10 954 i 9.0 956 f 6.0 944 f 12 955 f 4.0 961 f 4.0 ‘results shown in the table are biweight mean of measured ratios scan-by-scan, error is sown in percentage as 2u; ‘age for each step calculated as biweight mean on the scans. age for each grain and for that of the whole population are weighted average on the step results performed at the laboratory for isotope geology (lig), swedish museum of natural history, using a finningan mat 261 mass-spectrometer. data were collected in a peak-jumping mode, using a secondary electron multiplier in a sequence of 206pb-207pb-208pb-206pb-zo4pb. no correction for mass-fractionation was made. the correction for common lead was done using the measured 206pb/204pb ratio and initial lead isotope ratios of stacey & kramers (1975). the lead emission was observed at tempera tures of ca. 1470-1520°c. scan-by-scan data were recorded and the age for each scan was calculated, using the software designed by torsten persson at the lig. the age for each evaporation step has been calculated as biweighted mean of 10 to 20 scans, applying the histogram procedure of the ‘isoplot’ program of ludwig (1991) with the tuning constant 6 to decline outliers out of 6 a error limit. the age of each grain and the age of the zircon population have been calculated with weight average procedure of the ‘isoplot’ (ludwig 1991), using the results from all evaporation steps of the four zircon grains. dating results the results of the analyses are shown in table 2 and fig. 5. none of the analysed grains shows an increase of age from step to step. this implies that if the host rocks experienced any later thermal overprint, there was no thermaufluid-acting event high enough to reset the u-pb isotope system of the zircons after the crystallisation of these grains. grenvillian single-grain zircon pb age of a granitic rock 153 fig. 5. step evaporation diagram. first number before 1000 i i i i i i i i i evaporation step no. shadowed area gives average of the four grains. l some upward scattering of the results, e.g. grains 1 and 3, may suggest the presence of older (inherited) domains within the grains, though no recognisable discordant core has been noted. the lower age of grain 4 may have resulted from partial lead loss due to its metamict structure. the ages obtained are: grain i: 962 * 6.5 ma (7 steps), grain 2: 959 * 13ma (3 steps), grain 3: 968 f 9 ma (7 steps) and grain 4: 955 f 4 ma (5 steps). the biweighted mean of 21 steps, exclud ing grain 3 scan 3 due to a large deviation, from all four grains is 961 4 ma. interpretation of the results the phyllitic rocks surrounding the dated granitic rock are considered to be part of the biscayarhu ken formation, the uppermost structural unit of metamorphic rocks in the n-b-h subzone. the granitic rock intruded into the phyllitic rocks and the primary igneous texture was converted into cataclastic gneissose textures subsequent to the formation of the cleavages in the phyllitic rocks. petrographic and field observations suggest that the granitic rock was emplaced subconcordantly along the cleavages of phyllitic rocks as locally oblique sheets. the morphology and structure of the analysed zircon grains do not show any clear evidence of abrasion by detrital processes and their concentric zonal structures suggest a mag matic origin; therefore, the obtained ages, 961 & 4 m a in average, are considered to be the age of intrusion. accordingly, it is concluded that the formation of the phyllitic cleavages of the biscayarhuken formation is older than, or simultaneous with, the intrusion age of the granitic rock, ca. 960ma. this is consistent with the igneous ages obtained from the metagranite and corona gabbros from the north of richardvatnet by peucat et al. (1989). the age of the sedimentary protoliths of the metamorphic rocks of the biscayarhuken forma tion in the n-b-h subzone is mesoproterozoic. no evidence of supposed rift-related igneous activity around 620-660 and high-grade meta morphism around 455 ma argued in the rocks of the richarddalen group by gromet & gee (in press) can be detected in the zircon grains studied in this work, and the conditions during the caledonian events were not high enough to reset the u-pb isotope system of zircon in the biscayarhuken formation. this implies that the thrust duplex structures presently observed within the n-b-h subzone were developed after the middle ordovician metamorphic event of cale donian. acknowledgements. laboratory for isotope geology, swedish museum of natural history kindly offered the opportunity to cany out isotopic analyses. the field information given by a. n. sirotkin and a. m. teben'kov, polar marine geological expedition, lomonosov, russia, and t. gjelsvik of norwegian polar institute is deeply acknowledged. references balasov, ju. a,, peucat, j. j., teben'kov, a. m., ohta, y., larionov, a. n. & siratkin. a. n. 1996: additional rb-sr and single-grain zircon datings of caledonian granitoid rocks from albert land, northwest spitsbergen. polar res. 15(2), 15 3-1 65. chappell, b. w. & white, a. j. r. 1974: two contrasting granite types. pacific geol. 8. 173-175. dallmeyer, r. d., peucat, j. j . & ohta, y. 1990a: tectonother ma1 evolution of contrasting metamorphic complexes in northwest spitsbergen (biscayarhalvplya): evidence from 4 0 ~ 1 3 ' a r and rb-sr mineral ages. geol. soc. am. bull. 102, 653-663. 154 y. ohta & a. n . larionov dallmeyer, r. d., peucat, j . j.. hirajima, t. & ohta, y. 1990b: tectono-thermal chronology within a blueschist-eclogite complex, west-central spitsbergen, svaibard: evidence from 4"ar/'9ar and rb-sr mineral ages. lithos 24, 291-304. gayer, r. a,, gee, d. g., harlnd, w. b., miller, j . a,, spall, h. r., wallis, r. h. & winsnes, t. s. 1966: radiometric age determinations on rocks from spitsbergen. norsk polarinsf. skr. 137, p . 39. gee, d. g. 1966: a note on the occurrence of eclogite in spitsbergen. norsk polarinst. arbok 1964, oslo. 240-241. gee. d. g. & hjelle, a. 1966: on the crystalline rocks of northwest spitsbergen. norsk polarinst. arbok 1964, oslo. 31-45. gee, d. g. & moody-stuart, m. 1966: the base of the old red sandstone in central north haakon vii land, vestspits bergen. norsk polarinsf. arbok 1964. 57-68. gjelsvik, t. 1979: the hecla hoek ridge of the devonian graben between liefdefjorden and holtedahlfonna, spitsbergen. norsk polarinst. skr. 167, 63-7 1. gromet, l. p. & gee, d. g. in press: an evaluation of the age of high-grade metamorphism in the caledonides of bis kayerhalvgya, nw svalbard. geol. for. forhandl. 120. hjelle, a. 1979: aspects of the geology of northwest spitsbergen. norsk polarinst. skr. 167. 37-62. hjelle, a. & lauritzen. 0. 1982: geological map of svalbard 1 : 500,000, sheet 3g spitsbergen. northern part. norsk polarinst. skr. 154-c, 1-15. jager, e. 1979: introduction to geochronology. in jager, e. & hunziker, j. c. eds. lectures in isotope geology 1-12. springer verlag, berlin, germany. kober, b. 1986: whole-grain evaporation for 2"7ph/206pb-age investigations on single zircons using a double-filament thermal ion source. contr. miner. petrol. 93(4), 482490. kober, b. 1987: single-zircon evaporation combined with pb+emitter bedding for 207pb/2"6pb-age investigations using thermal ion mass-spectrometry, and implications to airconology. contr. miner. pefrol. 96(1), 63-7 1. ludwig, k . r. 1991: isoplot a plotting and regression program for radiogenic isotope data, version 2.56. u.s. geol. s m ~ . operi file rep., 9 1 4 5 . maniar, p. d. & piccoli, p. m. 1989: tectonic discrimination of granitoids. bull. geol. soc. ant. 101, 635443. muravsov, l. g. & mokin, ju. 1. 1976: stratigrafilleskoe rasrlenenie devonskih oienij 0. spicbergen. (stratigraphic subdivision of devonian deposits of spitsbergen) in: geologija sval'barda. leningrad. 78-9 1 . ohta, y. 1992: caledonian and precambrian history in svalbard a review. and an implication of escape tectonics. tectonophysics 231. 183-194. ohta, y . , hiroi, y. & hirajima, t. 1984 additional evidence of pre-silurian high-pressure metamorphic rocks in spits bergen. polar res., n.s., i , 215-218. peucat, j. j., ohta, y. & bernard-griffiths, j. 1989: u-pb, sr and nd evidence for grenvillian and latest proterozoic tectonothermal activity i n the spitsbergen caledonides, arctic ocean. lithos 22, 275-285. ravich, m. g. 1979: is there an early precambrian granite gneiss complex in northwestern spitsbergen. norsk polar insf. skr. 167, 9-28. stacy, j. s. & kramer, j. d. 1975: approximation of terrestrial lead isotope evolution by a two-stage model. earth plonuf sci. lett. 26, 207-22 1. impact of global change on the biogeochemistry and ecology of an arctic freshwater system john e. hobbie, bruce j. peterson, neil bettez, linda deegan, w. john o'brien, george w. kling, george w. kipphut, william b. bowden & anne e. hershey lakes and streams in the foothills near toolik lake, alaska, at 68"n have been studied since 1975 to predict physical, chemical and biological impacts of future global change. experimental manipulations include whole lake and continuous stream fertilization as well as removal and addition of predators (copepods, lake trout, grayling, sculpin). based on our evidence the following scenario is likely. warming thaws the upper layers of permafrost and streams and lakes become enriched with phosphorus. streams respond quickly with higher production of diatoms but animal grazers keep biomass changes to a minimum. fish productivity also increases. if phosphorus levels are too high, mosses become the dominant primary producer and sequester all of the nutrients. growth of arctic grayling under the present conditions only occurs in summers with higher than average stream flow. the present population would be stressed by warmer temperatures. when higher phosphorus levels reach lakes and cause slight eutrophication, the number of trophic levels will increase, especially within the microbial food web. warmer lake temperatures increase stratification and, combined with eutrophication, could decrease oxygen in the hypolimnion. oxygen levels will also decrease in winter under the ice cover. eventually this habitat change will eliminate the lake trout, a top predator. removal of lake trout results in a striking increase in abundance and productivity of smaller fish, including small lake trout, and the emergence of burbot as an alternate top predator. large species of zooplankton will become virtually extinct. j. e. hobble, b. j. peterson, n. bette: & limfci deegan, marine biological laboratory, woods hole, ma 02543, usa; w. j . o'brien, dept. of syslematics arzd ecology, universit?, of kansas, lnwrence, ks 66045, usa; g. w. kling. dept. of biology, universitv of michigan, anti arbor, mi 48109, usa; g. w. kipphut, murray state university, murray, ky 42071, usa; w. b. bowdeiz, landcare research, p.o. box 40, lincoln, 8152 new zealand; a. e. hershey, dept. of biologv, universit?, of north carolina greensboro, greensboro, nc 27402, usa. introduction toolik lake, on the north slope of alaska, is the site of a 25-year intensive study to predict the impacts of climate change on an arctic aquatic system. the streams and lakes here are surrounded by tussock tundra. t h e study involves experiments in which nutrients, top predators, and permafrost depth are manipulated, and it includes mathenia tical models of biology and physics. here we report predictions of impacts based only on those of our results that can be linked to the primary effect of future warmer temperatures, predicted by a variety of global climate models (e.g. chapman & walsh 1993). other effects are possible and rouse et al. (1997) stated that a decrease in run-off was also likely. however, this is controversial and it is generally thought that there will b e an increase in arctic precipitation with temperature warming. research site and history the research site is the tundra, lakes and streams near toolik lake, alaska (68"n. 149"w), in the northern foothills of the brooks range and some 180km south of the arctic ocean (fig. 1). hobbie et al. 1999: polar research 18(2), 207-214 207 fig. 1. location of toolik lake in arctic alaska along the trans-alaska pipeline. redrawn from deegan et al. (1999). temperatures average -8.4"c annually while may through august temperatures average 0.6, 8.1, 1 1.9, and 7.4"c. low hills, formed by glaciers, are covered with sedges and grasses dominated by cotton grass mixed with dwarf birch, low willows and forbs. soils are moist despite the low total precipitation of 200-300 mm. streams and small lakes are abundant; the 4th order kuparuk river and the 1.5 km2 toolik lake (d,,, 25 m) are the largest. the run-off season begins in late may, lakes thaw in mid to late june, and lakes and soils freeze in late september. data are available at www .mbl .edu/html/ecosystems/lterhtmvarc. html. the history of toolik lake research and descriptions of the observations on lakes and streams are given by hobbie (1997), o'brien, bahr et al. (1997), and hershey, bowden et al. (1997). the research has moved from (1) descrip tions of the aquatic environment and the rates of ecological processes to ( 2 ) small-scale experi mental studies of controls of productivity and of the abundance of plants and animals, and finally to (3) a series of long-term and large-scale experi mental manipulations to examine controls of processes as well as responses of whole systems to changes that included additional nutrients in tundra, streams and lakes, increases in air temperature, and changes in the top predators of lake ecosystems. in the following sections we report results of studies organized from primary to secondary effects of climate change. the only primary effect dealt with here is an increase in air temperatures. the secondary effects begin with physical-chemi cal effects of the thawing of permafrost, which lead to a release of phosphorus, and an increase in lake temperatures. secondary effects continue with effects of added phosphorus on primary producers and effects of temperature and eutro phication on the top predators in lakes and on the stream fish. primary effect air temperatures will increase: for more than 30 years, the air temperatures in arctic alaska have been increasing. data from barrow, for example, show an increase of 0.7"c per decade. this is much more rapid an increase than predicted by global climate models and appears to be a regional phenomenon, rather than a whole-arctic change (chapman & walsh 1993). secondary effects (physical-chemical) permafrost thawing will increase phosphorus in streams: the permafrost in arctic alaska is warming but has not yet begun to thaw (oster kamp 1994). central alaska, to the south, has had extensive thawing in recent years, with thermal erosion and slumping on hillsides. near toolik lake, we were able to test the effect of thawing at a site where several metres of surface gravel were removed from glacial kames for road construction in the early 1970s. a stream that now passes through one of these disturbed kames is turbid and also is unusually high in phosphate and other nutrients; phosphate levels (soluble reactive phosphate) in this stream are more than twice as high as in any other stream sampled in this watershed (n = 23). in six years of summer sampling, this stream, called the milkyway, is nearly always higher in phosphate concentration than the larger stream (toolik inlet) into which it feeds (fig. 2 ) . we calculate that the milkyway contributes about 10% of the inflowing water to toolik lake but 30% of the phosphate and nitrate. 208 impact of global change on the biogeochemistry and ecology of an arctic freshwater system o 6 1 0 4 o v 2 03 5 0 2 0 1 0 0 milhyway toolik inlet i tl i i year fig. 2. average summer concentrations of soluble reactive phosphorus in two streams of the toolik lake watershed. one stream, toolik inlet, was sampled where it entered toolik lake and the other (milkyway) at the point where it entered the toolik inlet stream. there was only one sample from 1992. the number of samples varied from 3 to 12 over the years; error b a r s indicate the standard error of the mean. our interpretation is that permafrost is melting and releasing stored nutrients. phosphorus input to lakes will increase hut sediment chemistry reduces impacts: the effects of increased nutrient loading on arctic lake ecosystems were studied in a long-term fertiliza tion experiment in lake n-2. the lake was divided with a polyethylene curtain, and the outflow half of the lake was fertilized for six years (1985-90) with inorganic nitrogen and phosphorus at a rate five times higher than the annual nutrient loading. as expected, phytoplank ton productivity and biomass increased i n re sponse to the added nutrients. however, the rate of increase in primary production accelerated during the last year of fertilization. the explanation for the acceleration lies in the interaction between phosphate and the very abundant iron in the sediments. this abundant iron, along with high concentrations of organic carbon and manganese, is characteristic of the sedimentary environments of arctic alaska (kip phut 1988; cornwell & kipphut 1992). prentki et al. (1980) observed that phosphorus in shallow arctic tundra ponds was strongly chemically bound to the abundant iron in the sediments. in lake n-2 (fig. 3), the added phosphorus became bound to the iron oxide layer for the first five years of fertilization and could not be recycled to overlying waters. by the last year of fertilization 40.0 lake n-2 la) i fertilized 10.0 n n year fig. 3. (a) primary productivity (annual) in the fertilized and control sides of the divided lake n-2. fertilizer was added from i985 through 1990. (b) phosphorus flux (average per day) from the sediments into the water of the fertilized side of lake n-2. (1990), the sedimentation of algae to the sediments had depleted the iron oxide layer because of iron sulfide formation, allowing large fluxes of phos phorus from the sediments. the rapid drop in phosphorus fluxes observed when fertilization ceased (1991) shows the importance of the unusual chemical nature of the arctic sediments in sequestering nutrients (sugai & kipphut 1992). lake temperatures will increase: the effects of a changing climate on the physics of toolik lake were predicted with the arctic lake model (alm), which simulates both physics and biol ogy. the physical portion of the model has daily weather data as the only input and uses an eddy diffusion model similar to that of henderson sellers (1984, 1986). for winter, the model uses an approach similar to gu & stephan (1990) and includes heat storage in the sediment. from this, the alm can simulate the annual thermal cycle of a lake (fig. 4) as well as the annual oxygen depletion cycle during both summer and winter. under a scenario of a 5°c air temperature increase, lake temperatures increased by ca. 3" while the ice-free season increased by seven weeks. higher order effects (biota) primary producers in streams: as shown in the previous section, phosphorus will likely increase hobbie et al. 1999: polar research 18(2). 207-214 209 toolik lake temperature 1993-94 measured 1 simulated 1 !i p 25 24 23 21 22 21 20 26 25 24 23 21 22 21 20 aug oct dec feb apr jun aug jun aug oct dec feb apr jun aug date fig. 4. (a) the output of the arctic lake model for temperature in toolik lake compared with real data (measured) for a full year. (b) real data (measured) for a single year in toolik lake compared with a simulation using a 5°c increase i n air temperature. in streams with warmer air temperatures. we investigated the biotic impacts of this increase with a manipulation experiment in the kuparuk river, now in its 16th year of phosphorus fertilization (fig. 5 ) . the river ecosystem re sponds to p fertilization at the final concentration of only 1 pm with increases in epilithic chlor ophyll and primary production, increases in insect abundance in several taxa, and increases in fish production (hershey, hiltner et al. 1988; bowden, peterson et al. 1992; deegan & peterson 1992). one remarkable finding is that the wide variation in discharge from year to year exerts even more powerful control over insect abundance and fish growth than the nutrient enrichment (deegan & peterson 1992; hershey, merritt et al. 1995). however, some taxa do better at high flow and others at low flow conditions and thus the stream community overall benefits from year to year variability in discharge. a major reorganization of the stream community took place after 7 or 8 years of fertilization (fig. 6) when a nutriophilic species of bryophyte, hygrohypnum sp., began to proliferate on the river bottom (bowden, finlay et al. 1994). this moss now dominates primary production, controls insect habitat structure and hence species composition, traps tremendous quantities of fine particulates, and sloughs quan tities of moss fragments and detritus during high discharge events. it may be having a negative impact on grayling production but more data are needed. prinzniy producers in lakes: an increase of the fluxes of nutrients from the landscape into streams and then into lakes can clearly alter the structure and function of lake ecosystems. in the toolik lake region, eutrophication has been studied in limnocorrals, in a divided lake, and in a whole lake. the limnocorrals showed that these arctic systems are potentially similar in response to temperate lakes; cyanobacteria bloomed (o’brien, hershey et al. 1992). the lake response ranged from a moderate increase in productivity in the divided lake (fig. 3) to a cyanobacterial bloom in a whole lake. the differences were likely caused by different amounts of the iron oxide layer in the two systems. secondaw producers: the secondary producers of lakes zooplankton, insects and fish are affected by changes in temperature as well as by the changes in oxygen brought about by eutro phication. one aspect of this is the effect on the habitat of the top predator, the lake trout. we have used the alm model to simulate the effect of 210 impact of global change on the biogeochemistry and ecology of an arctic freshwater system fig. 5. the kuparuk river data, 1983-1997. the temperature (bars) and discharge data (solid points connected by a line) are at the dalton highway crossing. the epilithic chlorophyll amounts, bneris density, and adult grayling growth are seasonal means for a 2 bm reach upstream (reference) and downstream [fertilized) from the site where phosphorus was added continuously each summer. 9 80 3 60 m 2 40 - a 20 c 5 8 0 c -20 discharge & temperature i 2 , d discharge t 5 0 reference fertilized - - -~ --+-- i ’ 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 4.0 epilithic chlorophyll 3.5 7.1 2.9 pg/crn2 reference n 5 3.0 3 2.5 = 6 2.0 1.5 1.0 8 0.5 0.0 ” 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 12000 t baetis & 8000 st v . 8 4000 2000 0 1 0 reference fertilized t a i 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 hobbie et al. 1999: polar research 18(2). 207-214 21 i distribution of hygrohypnum spp. kuparuk river 1992 8000 1 4downstream dripper moss cover -t po. concentration -1 -0.6-0.5-0.2 0.5 1 2 4 6 6 10 12 14 16 11 1.5 1.0, s 3 0.5 9. 0" 0.0 river location (km) fig. 6. the distribution of the phosphorus concentrations for one date in august 1992, and of the moss hygrohypnum upstream and downstream of the phosphorus addition (dripper) in the kuparuk river. the moss cover is the mean of 5 or 10 transects of at least 100 observations per transect. data provided by w. b. bowden. increased nutrient loading and climate change on lakes of differing depths (fig. 7). the depths where lake trout can thrive are indeed limited; climate warming of a few degrees will greatly reduce the habitat for these fish. the biological portion of the alm model uses nutrient loading and sunlight intensity as inputs to simulate summer phytoplankton production and zooplank no warming -2 deg warming .."--' 5 deg warming 20 l 02 depleted under ice i i o l i i i i i i i 0 2 4 -6 8 phosphorous (mmol/mj/yr) fig. 7. results from runs of the arctic lake model showing the critical combinations of the maximum depth of the lake and the phosphorus loading rate that produces a hypolimnion with less than 3 mg o2 liter-'. this is the lower threshold for lake trout survival. the area of low oxygen increased with 2" and 5°c increases in the climate. chironomid response to sculpin addition in lake e l 6000 n $ 2 .* 4000 s q ul 2000 0 , 15 jul91 3 jd 95 31 jul96 fig. 8. chironomid abundance in lake e-i, near toolik lake, before and after sculpin addition to the lake in the summer of 1995. data provided by a. e. hershey. ton biomass by integrating rate equations for nutrients, algae and zooplankton (pascual 1994). the remaining phytoplankton is then transferred to deep water to induce summer and winter oxygen depletion. when the lake trout are lost from these lakes in the future, what will be the biotic consequences? it is well known that in large lakes lake trout play a keystone role and control the size and density of fish and other animals in the lake food web. in toolik lake it appears that fishermen have removed the largest lake trout with a subsequent release from predation of smaller fish, such as grayling and young lake trout. as a result, the smaller fish have become abundant and eliminated the large zooplankton species (hobbie et al. 1995). experimental manipulations have shown that lake trout predation also impacts the abundance of the snail lymnaea (merrick et al. 1992) and the density and habitat distribution of slimy sculpin (hanson et al. 1991; mcdonald & hershey 1992). when we tested our hypothesis about sculpin and removed all large lake trout from a lake, we were surprised to find that burbot, a minor part of the community, suddenly became very abundant. instead of freeing the sculpin from predation, the experiment caused the emergence of another effective predator and so the sculpin became even more concentrated in the suboptimal rocky littoral habitat. slimy sculpin are also effective predators of chironomids and when they themselves are free from predation they limit their prey to low 212 impact of global change on the biogeochemistry and ecology of an arctic freshwater system densities in toolik lake (cuker et al. 1992; goyke & hershey 1992). this was shown dramatically in an experiment in which sculpin, newly introduced into a lake, drastically reduced the chironomid numbers (fig. 8). we have recently added another predator, adult grayling, to a small fishless lake and found that they eliminated the very largest zooplankton but not the intermediate-sized zoo plankton. thus, elimination of lake trout by a climate change will have a variety of conse quences as the impact cascades down the food web. nutrient increases in the future will have impacts that extend beyond the primary producers; this results from the control of food webs by the nutrients and primary production, the bottom-up control. in a limnocorral experiment we found added nitrogen and phosphorus greatly stimulated phytoplankton growth and, after a year’s lag, zooplankton also responded with increased den sities (o’brien, hershey et al. 1992). in an experiment in which nutrients were added to one side of a divided lake, the phytoplankton (fig. 3) and most zooplankton species increased in abun dance while cyclops scutifer showed no response; this species is thought to feed on the microbial food web. hershey (1990) found that the snail lymnaea increased in abundance with added nutrients but chironomids, controlled by predac eous sculpin, did not. finally, there are also important impacts of a warming climate on the arctic grayling, the single fish of streams near toolik lake. this impact was studied using a long-term record, extending over a decade, of changes in weight of individual grayling sampled at the beginning and the end of each summer in the kuparuk river and oksru kuyik creek. some summers were warmer than others and some had higher water discharge than others (fig. 5) which allowed a stepwise regres sion analysis to be carried out (deegan et al. 1999). for adult fish, 42% of the variance in growth rate could be accounted for by the combination of nutrient level, mean summer discharge, and consecutive days with extreme low flow. that is, grayling growth was reduced in years with low flows and high temperatures. this correlation between adult arctic grayling growth rate and river discharge may be due to a balance between food availability and metabolic demands. high discharge sweeps benthic invertebrates into the drift, making them accessible as food for drift feeding fish, but the metabolic cost of swimming in the faster currents may be countered by increasing food intake, resulting in positive growth (nielsen 1992). conversely, low river discharge increases water temperature which also increases metabolic demands (stolbov & alikin 1977) but at the same time drift is reduced and food is less. the combination of low river discharge and relatively high water temperatures can prevent the adult fish near toolik lake from gaining weight, or even cause them to lose weight (e.g. 1990, 1993, 1996). given the complexity of the relationships among grayling growth, temperature and discharge, it is difficult to predict the effects of a warmer climate except to say that this particular population would find it difficult to survive. however, grayling are found throughout alaska in stream waters much warmer than those near toolik lake so the potential for survival does exist in the species’ genetic pool. we do not know if this population of fish will be able to adapt to the new climate regime. conclusions global change will likely cause a release of phosphorus from melting permafrost into streams and a change in the top predator of lakes caused by a shrinking habitat for lake trout. streams and lakes will become more productive but the structure of the lake food web will change as the lake trout become extinct in this region. acknowledgeinents. the research was funded by the national science foundation under the lter and the arctic natural sciences programmes. references bowden, w. b., peterson, b. j . , finlay, j. c. & tucker, j. 1992: epilithic chlorophyll a, photosynthesis and respiration in control of a tundra stream. hydrobiologia 240, 121-132. bowden, w. b.. finlay, j. c. &maloney, p. e. 1994: long-term effects of po4 fertilization on the distribution of bryophytes in an arctic river. freshwater b i d . 32, 4 4 5 4 5 4 . chapman, w. l. & walsh, j. e. 1993: recent variations of sea ice and air temperatures in high latitudes. bull. am. meteorol. soc. 74, 3 3 4 1 . cornwell, j. c. & kipphut, g. w. 1992: biogeochemistry of manganeseand iron-rich sediments in toolik lake, alaska. hydrobiologia 240, 45-60. hobbie et al. 1999: polar research 18(2), 207-214 213 cuker, b. e.. mcdonald. m. e. & mozley, s. c. 1992: influences of slimy sculpin (cottus cognatus) predation on the rocky littoral invertebrate community of an arctic lake. hydrobiologia 240, 83-90. deegan, l. a. & peterson, b. j. 1992: whole river fertilization stimulates fish production in an arctic tundra river. can. j. fish. aquaf. sci. 49, 1890-1901. deegan, l. a., golden. h., harvey, c. j. & peterson, b. j. 1999: the influence of environmental variability on the growth of age 0 and adult arctic grayling. trans. am. fish. soc 128, 1163-1 175. goyke, a. p. & hershey, a. e. 1992: effects of fish predation on larval chironomid (diptera: chirononiidae) communities in an arctic ecosystem. h.vdrobiologia 240, 203-21 1. gu, r., & stefan, h. g. 1990: year-round temperature simulation of cold climate lakes. cold reg. sci. technol. 19, 147-160. hanson, k. l.. hershey, a. e. & mcdonald. m. e. 1992: a comparison of slimy sculpin (cotfus cognatus) populations in arctic lakes with and without piscivorous predators. hvdro biologia 240, 189-202. henderson-sellers, b. 1984: engineering linznology. boston: pitman. henderson-sellers, b. 1986: calculating the surface energy balance for lake and reservoir modeling: a review. rev. geophys. 24. 625-649. hershey, a. e. 1 9 9 0 snail populations in arctic lakes: competition mediated by predation. oecologia 82, 26-32, hershey, a. e., hiltner, a. l., hullar, m. a. j., miller, m. c.. vestal, r. j., lock, m. a,, rundle, s. &peterson, b. j. 1988: nutrient influence on a stream grazer: orthocladius micro communities respond to nutrient input. ecology 69, 1383-1392. hershey, a. e., memtt, r. w. & miller, m. c. 1995: insect diversity, life history, and trophic dynamics in arctic streams, with particular emphasis on blackflies (dipfera; sirnuliidae). in f. s . chapin 111 & k. koerner (eds.): the role of biodiversify in arcfic and alpine tundra ecosystems. pp. 283-295. berlin: springer. hershey, a. e., bowden, w. b., deegan, l. a., hobbie, j. e., peterson, b. j . , kipphut, g. w., kling, g. w., lock, m. a,, merritt. r. w., miller, m. c., ruhlee, p. & vestal, j. r. 1997: the kuparuk river: a long-term study of biological and chemical processes in an arctic river. in a. m. milner & m. w. oswood (eds.): freshwaters of alaska: ecological syntheses. pp. 107-120. new york: springer. hobbie, j. e., deegan, l. a., peterson, b. j., rastetter, e. b., shaver, g. r., kling, g. w., o’brien, w. j., chapin. f. s., miller, m. c., kipphut. g. w . , bowden, w . b., hershey, a. e. & mcdonald, m. c. 1995: long-term measurements at the arctic lter sites. in t. m. powell & j . h. steele (eds.): ecological time series. pp. 3 9 7 4 0 9 . new york: chapman and hall. hobbie. j. e. 1997: history of limnology in alaska: expeditions and major projects. in a. m. milner & m. w. oswood (eds.): freshwaters ofalaska: ecological syntheses. pp. 45-60. new york: springer. kipphut, g. w. 1988: sediments and organic carbon cycling in an arctic lake. in e. t. degens et al. (eds.): transport of carbon and minerals in rnajor world rivers. lakes, and estuaries. part 5 . pp. 129-1 35. hamburg: scopekjnep. (also published in sonderbd. 66 by mitt. geo1;palaont. inst., university of hamburg.) mcdonald, m. e. & hershey, a. e. 1992: shifts in abundance and growth of slimy sculpin in response to changes in the predator population in an arctic alaskan lake. hydrobiologia merrick, g. w.. hershey, a. e. & mcdonald. m. e. 1992: salmonid diet and the size, distribution, and density of benthic invertebrates in an arctic lake. hydrobiologia 240, 225-234. nielsen, j. l. 1992: microhabitat-specific foraging behavior, diet. and growth of juvenile coho salmon. trans. am. fish. soc. 121. 617-634. o’brien. w. j., bahr, m.. hershey, a. e., hobhie, j . e., kipphut. g. w., kling, g. w., kling, h., mcdonald, m., miller, m. c., rublee, p. & vestal, j. r. 1997: the limnology of toolik lake. in a. m. milner & m. w. oswood (eds.): freshwaters of alaska: ecological syntheses. pp. 61--106. new york springer. o’brien, w. j., hershey, a,. hobhie, j., hullar, m . a,, kipphut, g. w., miller, m. c., moller, b. & vestal, j. r. 1992: control mechanisms of arctic lake ecosystems: a limocorral experiment. hydrobiologia 240, 143-188. osterkamp, t. 1994: evidence for warming and thawing of discontinuous permafrost in alaska. eos 75(44), 85. pascual, m. 1994: periodic response to periodic forcing of the droop equations for phytoplankton growth. j . math. biol. 32, 743-759. prentki, r. t., miller, m. c., barsdate, r. j., alexander, v.. kelley, j. & coyne, p. 1980: chemistry. in j. e. hobbie (ed.): lininology of tundra ponds. pp. 7 6 1 7 8 . stroudshurg, pa (usa): dowden. hutchinson & ross. rouse, w. r.. douglas, m. v., hecky, r. e., hershey, a. e., kling, g. w., lesack, l., marsh, p., mcdonald, m., nicholson, b. j.. roulet, h. t. & smol, j. p. 1997: effects of climate change on the freshwaters of arctic and subarctic north america. hydrol. processes 11, 873-902. stolbov. a. ya. & alikin, yu. s. 1977: temperature dependence of active metabolism and swimming speed of the baikal arctic grayling, thyinallus arcticus baicalensis. (engl. trans. vopr. ikhtiol.) j. zchthyol. 17(1), 178-179. sugai, s. f. & kipphut, g. w. 1992: the influence of light and nutrient addition upon the sediment chemistry of iron in an arctic lake. hydrobiologia 240, 91-101. 240, 2 19-224. 214 impact of global change on the biogeochemistry and ecology of an arctic freshwater system energy costs during incubation in svalbard and willow ptarmigan hens gelr wing gabrielsen a n d s i g m u n d unander gabrielsen, g.w. & unander, s. 1987: energy costs during incubation in svalbard and willow ptarmigan hens. polar research 5 n.s., 59-69. studies o f wild and captive willow and svalbard ptarmigan hens have allowed us to estimate the daily energy cost during incubation. i t was similar for the two species, varying between 70-85 kcal per day depending on number of eggs, nest insulation, ambient temperature, number of foraging periods and total time spent away from the nest. daily energy cost during incubation was is-20% above resting metabolic rate in non-incubating hens but only 45--55% of that in free-living non incubating hens. incubating hens reduced their energy expenditure through high nest attentiveness. a reduction in food intake during incubation led to loss in body weight. geir wing gabrielsen. norwegian polar research institute. rolfstangveien 12. 1330 oslo lufthavn. norway; sigmund unander. division of environment. regional commissioner of aust agder. holbergs gate 54,4600 kristiansand. several galliform species live and breed in arctic and subarctic regions where temperatures below 0" c and snow are not uncommon during nesting. successful reproduction involves regulation of egg-temperature within optimal limits for em bryonic development, a process dependent upon heat flow from the bird, nest attentiveness and nest insulation. ptarmigan hens (lagopus sp.) leave the nest to forage 2-5 times a day (barth 1949; pulliainen 1978; erikstad 1985). the rate of egg cooling depends mainly on ambient tem perature and the time spent away from the nest. as in many single-sex incubators, ptarmigan hens have t o rewarm the eggs after each foraging period, as well as keeping the clutch of eggs at incubation temperature. indirect methods of estimating the cost of avi an incubation include measurements of heat loss from the eggs (kendeigh 1963), the clutch mass method (west 1960; ricklefs 1974) and heat budget modelling (walsberg & king 1978). di rect measurements of incubation cost have inc luded measurement of food intake (riddle & brancher 1934; el-wailly 1966; brisbin 1964) and oxygen consumption or carbon dioxide pro duction (norton 1973; mertens 1977, 1980; bie bach 1979; gessaman & findell 1979; vleck 198 i ; grant & whittow 1983 ; haftorn & reinert sen 1985). gabrielsen & steen (1979) measured heart rate a n d egg temperature in incubating willow ptarmigan hens and suggested a relation ship between egg temperature and energy cost of incubation. in the present study measurements of body weight, food intake, egg, nest and ambient tem perature, heart and respiration rate, oxygen con sumption and carbon dioxide production of wild a n d captive willow ptarmigan (lagopus lagopus lagopus) and svalbard ptarmigan (lagopus mu tus hyperboreus) hens are used to determine the energy cost of incubation and the nesting strategy of these birds. methods field investigations on wild birds were conduct ed during the summers of 1981 and 1982. five willow ptarmigan hens were studied on karlsay island, troms county, norway (70" n), and four svalbard ptarmigan hens at n y k e s u n d on the western coast of spitsbergen (79" n). ptarmigan hens were netted on the nest and fitted with ecg transmitters (sintef, trei ) fastened to a wire frame that was mounted on the bird in rucksack fashion. insertion of the electro des was performed under local anesthesia with one electrode placed close to the heart and the 60 other under the abdominal skin (gabrielsen & steen 1979). total weight o f t h e rucksack and the 100 mhz transmitter ( w i t h batteries for 400-600 hrs operation) was 23 g. heart rate signals were received through a directional yagi antenna to a commercial fm-radio and recorded on cassette tapes for later analysis. heart and respiration rates were later derived by means of an on-line microcomputer. heart and respiration rates were averaged for 5 sec periods during resting, walk ing and when hens started incubating cold eggs. the values were calculated as the average of these 5 sec periods. behavioural observations were made by a hidden observer through a tele scope from at least 50 m distance. egg, nest and ambient temperatures were recorded on a data logger (aanderaa dli ) . one unfertilized ptar migan egg, with copper-constantan thermo couple glued sub-surface on the upper side of the egg. was fastened in a fixed position in the middle of the nest. other thermocouples were placed at the bottom of the nest to record nest temperature. and 10 cm above the ground level to record ambient temperature. daily precipitation was measured at the meteorological stations i n tromso and ny-alesund. ptarmigan hens of both species were caught and weighed 2-3 times during the incubation period. experiments on two captive hens of each spe cies were carried out at the department of arctic biology. university of tromso, norway. each hen with her mate was placed in an outdoor room (0.5 x 2 m ) containing a metabolic chamber in which the eggs were laid. all four hens laid a normal clutch of 8i2 eggs. the males were removed just prior to incubation. modified pellet ed chicken food (moss & hanssen 1980) and water were given ad lihirum. food intake was measured every other day before. during and after the incubation period. after two weeks of incubation one hen of each species was equipped with an e c g transmitter, and one egg w i t h a thermocouple was placed in the middle of the nest. ambient temperature was recorded both inside and outside the metabolic chamber b> thermocouples connected to a fluke (2190 a) digital thermometer. metabolism was measured i n a n open system, the metabolic chamber (40 x 30 x 2s cm) was connected to a carbon dioxide (le!.bold-heraeus. b i n o s 2 ) and an oxygen (applied electro-chemistry inc. s-3 a, ri and n-22 m ) analyzer through a plastic tube from the outdoor room. air was dried (cac12) and pumped through the system with a flow of 2.5-3.0 vmin. airflow was measured in each experiment with a tri-flat flowmeter (fischer & porter, type 10 a 3200). all results are given at stp. an energy equivalent of 4.8 kcal per 1 o x y g e d h o u r was used (schmidt-nielsen 1975). i kcal corresponds to 4.185 kj (kleiber 1975). cooled eggs (+4"c) were exchanged with the hens' own clutch during each experiment. simul taneous measurements were made of the hens' heart and respiration rates, carbon dioxide pro duction and oxygen consumption, egg and am bient temperature, following the initiation of incubation of each cooled clutch. two-tailed t-test was used to determine the significance of differences between means. re sults are reported as mean & standard deviation. the regression line in fig. 7. was calculated by using least-squares method of linear regression. results field in vestiga r i m willow ptarmigan. in wild willow ptarmigan hens the heart rate increased at each inspiration and decreased at each expiration (fig. i). the mean for incubating and undisturbed hens was 138 beatslmin (b.p.m.) and respiratory rate was 25.2 breaths/min (br.p.m.) (table i ; fig. la). within 5 to 10 sec after settling on the eggs. after a foraging period, heart rates rose to a mean maximum of 534 b.p.m. and respiratory rate to 35.2 br.p.m. (table 1 : fig. ib). the duration of the tachycardia period was associated with the length of time spent away from the nest and the ambient temperature (gabrielsen & steen 1979). normally 40 to 80 minutes passed before heart and respiration rates had returned to resting levels. a temporary increase in heart and respira tion rates occurred each time the eggs were turned and during periods of low ambient temperature. hens left the nest 3-s times a day (table 2: fig. 2). willow ptarmigan hens were away from the nest for mean periods of 16.2 minutes during which the egg temperature dropped from 3 2 ° c 61 fig. 1 . example of heart and respiration rates of a wild incubating willow ptarmigan hen: a) incuba ting, b) 5 min after settling on cold eggs. heart rate increased at each inspira tion and decreased at each expiration. fig. 2. egg, nest and ambient temperature during one day of incuba tion in a wild willow ptar migan hen. drops in egg and nest temperature indi cate periods away from the nest. t.caf,lml" i i 10 sec. 5 0 0 1 ~ time 4 0 36 3 2 2 8 w u 3 24 u 2 0 w a 3 1 6 w i it n e s t a 1 12 ~ 06 12 18 24 time (hour) to a mean of 26.7"c (table 2). drop in egg tem perature was related to ambient temperature and time spent away from the nest. ambient tempera tures and mean daily precipitation during the month of june, which was the main incubation period, are given in table 3. the number of foraging trips was reduced from 4.1 to 3.3 per day (p < 0.02, t-test) during periods of precipitation. body weight dropped on the average 19.5% (or 100 g) from the end of egg laying until hatching (table 4). hen weights at the end of the incuba tion period showed a wide range, from 450 to 550 grams (mean 498.6 g). two of seven hens that were captured late at incubation deserted the nest. both had low body weights (440 and 475 g). svalbard ptarmigan. the mean heart rate of incubating and undisturbed svalbard ptarmigan hens was 155 b.p.m. and the respiratory rate 25.3 br.p.m. when moving to or from the nest, mean heart rate was 205 b.p.m. and respiratory rate 28.5 br.p.m. (table i). heart rate rose to a mean maximum of 442 b.p.m. within 510 sec after settling on the eggs after a foraging period, and the respiratory rate to 35.5 br.p.m. (table 1 ; fig. 3). heart and respiration rates then declined gradually to resting level within 30-60 min. but increased each time the hen turned her eggs. periods of increased heart and respiration rate occurred during normal incubation at intervals of about 10 minutes (fig. 3). 62 tahle i. mean heart (b.p.m.) m d respiration (br.p.m.) rates of wild and captive ptarmigan hens. species number resting walking start of of birds incubating cooled eggs b.p.m. br.p.m. b.p.m. br.p.m. b.p.m. br.p.m. x + s d x + s d x 2 s d x + s d x + s d x k s d willow wild 5 1382 15.0 2 5 2 f 1.3 224-t 17.0 28.0+ 1.4 534k24.0 35.2-t 1 . 1 ptarmigan hens captive 2 l 9 0 f 14.0 26.02 1.4 290k 14.0 3 i . o + 1.4 460k 14.0 3 6 . 0 f i . 0 svalbard wild 4 1 5 5 k l 9 25.3kl.o 205+ 19.0 28.5k1.9 4 4 2 2 7 1 . 4 35.5k1.9 ptarmigan hens captive 2 2oof28 26.0f 1.0 2 7 0 f 14.0 3 3 . o k 1.4 400k28.0 37.0k 1.4 table 2. mean \slues for nest attentiveness, duration of absence and drop in egg and nest temperature in wild incubating ptarmigan hens. species number number duration egg temperature of birds/days of times of absence ( " c ) upon retum away from (min) ing to the nest nest per day ( x + s d ) (x -t sd) ( x ? sd) willow ptarmigan 3: 17 4. i f 0.7 1 6 . 2 t 6 . 0 26.1 k 0.9 hens sval bard ptarmigan hens ? / 7 2.9 2 0.4 14.3 k 3.6 25.6 2 i .2 table 3. mean daily ambient temperature and precipitation in tromsa and ny-alesund (meteorological data) during the incubation period (june 1 to july 1 1981-82 for willow ptarmigan hens, and june is to july 15 1981-82 for svalbard ptarmigan hens). ~ location \'ear mean daily absolute max. absolute min. number of mean daily amb. temp."c temp. ' c temp. "c days with precipi during the during the during the precipitation incubation incubation incubation tation ( > l m m ) period period period tromso 1981 6.1 k 3.4 13.5 -0.8 9 4.4 1982 s . 3 f 4 . 1 17.5 -1.2 14 4.2 ny1981 2.6 k 1.8 9.4 -2.0 5 2.9 alesund 1982 2.9 f 2.6 6.9 -0.8 3 2.4 ( x k s d ) 63 600 500 400 300 200 100 t i l l i i i i 10 ji c 400 i ji 30 40 50 60 time ( m i d fig. 3. heart rate recordings from a wild nesting svalbard ptarmigan hen. a walking after leaving the nest. b flying away from the nest. c at the nest just prior to incubation. d initiation of incubation (and start of time scale). e a fulmar (fulmurusgluciulis) flies over the nest. f ~ a period of tachycardia without any change in behavior, probably due to shivering and heating ofthe clutch. 6 4 the hens left the nest 2 3 times a day (table 7 ) and were away from the nest an average of 14.3 minutes at each absence. during the absence, egg temperature dropped from 32°c to a mean of 25.6-c (table 2), depending on ambient temperature and duration of absence. ambient temperature during the main incubation period and mean daily precipitation, between june 15 and july 15, is given in table 3. body weights dropped on the average 20.8°h (or 105 g) from the end of egg laying until hatching (table 4). table 4 . body mass ( m e a n in grams * sd) of wild and capti\e svalbard and willow ptarmigan hens at the end of egg laying and at hatching. body mass body mass at t h e end of at hatching egg laying time (.a ( x f s d ) ( x + s d ) svalbard wild 613.4+ 37.9 507.9 2 23.0 ptarmigan ( n = 19) ( n = 12) hens captive 617.5+ 10.6 507.5538.9 ( n = 2) ( n = 2) willow wild 595.6 * 30.2 498.6 * 32.5 ptarmigan ( n = 9 ) ( n = 7 ) hens captive 602.5 5 17.7 497.0 * 14. i ( n = 2 ) ( n = 2 ) la bora t o y e.uperiments willow ptarmigan. -the two captive incubating willow ptarmigan hens had a mean resting heart rate of 190 b.p.m. and a respiratory rate of 26.0 br.p.m. heart rates increased to 460 b.p.m. and respiration rates to 36.0 br.p.m. when returning to an artificially cooled clutch and declined to resting level within one hour (table 1 ) . during this period the egg temperature reached a stable level of 36-38°c. the increase in heart and respiration rate was accompanied by a more than two-fold increase in metabolic rate (table 5). the metabolic rate declined as the egg temperature rose. ilram w i l l o w ptarmigan hen svalbard ptarmigan hen 120 prelaying laying i incubation fig. 4. food intake (dry weight) before, during and after incubation in one captive willow ptarmigan and svalbard ptarmigan hens. food intake during incubation was 32% of that prior to egg laying (table 5 ; fig. 4). body weight decreased 22y0 (table 4; fig.5) during incuba tion. svalbard ptarmigan. captive incubating sval bard ptarmigan hens had a resting heart rate of 300 b.p.m. and a respiratory rate of 26.0 br.p.m. heart rate increased to a mean maximum of 400 b.p.m. and the respiratory rate to 37.0 br.p.m. after returning to artificially cooled eggs (table i ) . at the same time the metabolic rate increased and reached a maximum of about 2 times resting level (table 5 ; fig. 6). heart and respiratory rates and metabolism gradually declined to resting levels 40-60 min after retur ning to the eggs. there was a significant correla tion between heart and metabolic rate (fig. 7, least-squares regression analysis; f,, 1 1 = 152.49, p < 0.01). food intake during incubation was 37% of that prior to egg laying (table 5 ; fig. 4). body weight decreased i8% during incubation (table 4 ; fig. 5). 65 table 5. metabolic rate (mean in kcal/day+sd) and food intake (mean in gramksd, dry weight) in captive willow and svalbard ptarmigan hens. metabolic rate food intake (kcal/day) (gram) resting start of prelaying egglaying incubation incubating cooled eggs (x + sd) ( x + sd) ( x -t sd) ptarmigan 67.5 f 2.5 169.0 f 4.2 61.3+ 11.9 74.3 & 4.8 19.9-t 3.9 willow hens number of birds/ 1 / 5 1 / 5 2/10 2/10 2/10 measurements svalbard ptarmigan 62.0f4.5 163.2f2.9 18.3 k 2.9 100.5f5.1 29.2 f 2.4 hens number of birds/ 2/6 2/6 218 218 218 measurements energy budget calculations based on measurements of oxygen consumption, carbon dioxide production and nest attentive ness we calculated the energy expenditure for wild, incubating hens of the two species in the following way: expenses: incubating willow and svalbard ptarmigan hens had a mean resting metabolic rate (rmr) of 67.5 and 62 kcal/day, respectively. the energy cost for foraging activity (2 times rmr, 15 min away each time the hens left the nest) and re-heating of eggs after foraging ( 2 times rmr, 60 min after foraging) was calculated to be 3.5 and 3.2 kcal (willow and svalbard ptarmigan hens, respectively) each time they left the nest. each species left the nest on average 4.1 (willow) and 2.9 (svalbard) times a day ( p < 0.01, t-test). this added another 14 kcal/day in willow ptarmigan and 10 kcall day in the svalbard ptarmigan to the daily energy budget (table 6 ) . zncome:while away from the nest both species eat 15-25 grams (wet weight) of food (gabriel sen, parker & elvebakk unpublished; unander et al. 1985). a food intake of 20 grams corre sponds t o an energy intake, based on experi ments of food digestibility (moss & hanssen 1980) and caloric equivalent of protein (schmidt-nielsen 1975), of 18 kcal per meal (70% water, 70% metabolic efficiency). the energy in take was therefore 72 kcal/day (4 foraging trips) in willow and 54 kcallday (3 foraging trips) in svalbard ptarmigan hens (table 5). wild willow ptarmigan lost 100 g while wild svalbard ptarmigan lost 105 g during incubation. while svalbard hens show a decrease in body fat from june t o july (mortensen et al. 1983), there is only 2% body fat available in willow ptarmi gan hens (grammeltvedt 1978). 98 g protein and 2 g fat correspond to 10 kcal/day, 21 days of incubation, 60% body water, caloric equivalent of protein 4.8 kcal/g (d.w.) (kleiber 1975) and 7.7 kcal/g for fat (mortensen & blix 1985b). svalbard ptarmigan hens lose 30 g of fat and 75 g of proteins during incubation (mortensen et al. 1983). this gives an energy gain of 18 kcal/ day, 7.7 kcal/g for fat (mortensen & blix 1985b) (table 6). 66 3ram 700 svalbard ptarmigan willow ptarmigan i 6 0 0 :~ e w 5 0 0 n 400 --. april m a y june i july i months fig. 5. body weights measured from april to the middle of august in one captive willow ptarmigan and one svalbard ptarmigan hen. (.:a1 o a " ' metabolic response on cold eggs a _ resting metabolic l e v e l a j o 0 i = 5 0 f w c ~~ 2 5 5 0 7 5 roo 1 2 5 time c r n l n ) 5 ?ti ~ m e t a b o l i s m w i k ~ fig. 6. metabolism upon returning to cold eggs in one captive svalbard ptarmigan hen (ta = 10°c). f i g . 7. the relationship between heart ( b p m ) and metabolic rate (w/kg) in an incubating svalbard ptarmigan hen. 67 table 6 . daily energy budget (kcal/day) calculations of wild svalbard and willow ptarmigan hens. energy output energy intake resting extra cost during total food weight daily metabolic incubation: energy intake loss energy rate to keep eggs warm, output cost during foraging activity and incubation re-heating of eggs, heating of eggs after foraging. willow ptarmigan 61.5 14 81.5 1 2 10 82 hens svalbard ptarmigan 62.0 10 12,o 54 18 1 2 discussion the daily energy cost during incubation in wild ptarmigan hens varied between 70-85 kcal/day. this was 15-25% above resting metabolic rate in non-incubating hens, which corresponds t o 20-30% found in smaller birds (biebach 1981; vleck 1981; haftorn & reinertsen 1985), but 45-55% of the metabolism of free living willow ptarmigan (moss 1973). heating of cold eggs is probably achieved by shivering thermogenesis (taien et al. 1986). aulie (1976) found a coupling between activation of the pectoral muscles and the heart rate during shivering in the ptarmigan. increased circulation during shivering will provide sufficient oxygen to the muscles, and the heat produced is imme diately distributed to the brood patch. midtgard et al. (1985) found vasodilation and increased blood flow at the brood patch site of cooling. this supports suggestions by gabrielsen & steen (1979) that warming of the eggs is facilitated by increased blood flow to the brood patch. wild willow ptarmigan hens quadrupled while captive hens were found to double their heart rate when returning to cold eggs (gabrielsen & steen 1979). this difference in heart rate between wild and captive hens is probably related to physical fitness; wild birds showing a lower resting rate and a higher maximum heart rate com pared to captives. in captive ptarmigan hens of both species the two-fold increase was accompa nied by a two-fold increase in metabolic rate. despite the good relationship between heart and metabolic rate in laboratory studies, one should be aware of this when transforming heart and metabolic relationships t o the wild birds. both species incubate within the thermal neu tral zone but close to the lower critical tempera ture which for willow ptarmigan hens in summer plumage is 0°c (mortensen & blix 1985a). it was suggested by haftorn & reinertsen (1985) that the energy cost of incubation increases when air temperature falls below the lower critical tempe rature. this is true, but as shown in the present study, the energy cost in ptarmigan hens is also increased above this lower critical temperature during certain periods. while incubating at low ambient temperatures, above 0" c , both species showed short periods (20-30 seconds) of in creased heart and metabolic rate. these periods of increased heart rate and oxygen consumption, which were 15-3oyo above resting level, must be regarded as being due to the extra cost of keeping the eggs at incubation temperature. the eggs must be regarded as a poorly insulated extension 68 of the bird’s body that usually does not contri bute to the heat production. an incubating bird and her eggs must be treated as one organism. after foraging the eggs are cooled, and the incu bating hen must produce additional heat to compensate for a lowered egg temperature, or she must increase heat production due to a lowered body temperature. during periods of precipitation and low am bient temperature wild willow ptarmigan hens reduced foraging periods from 4 to 3 times a day. eggs cool faster under these conditions and the cost of rewarming would then be greater. a reduction of one foraging period per day is cal culated to have a negative effect of 14 kcal/day in willow ptarmigan hens. less energy necessary for feeding, locomotion and warming will have a positive effect on the total energy budget for the bird, provided that it has extra energy resources (i.e. body fat, as svalbard ptarmigan hens) to compensate for one less meal per day. the result will be, as observed in o u r study, that willow ptarmigan hens must fast when the external temperature reaches minimal levels and precipi tation is high. during cold weather, and especial ly when it is raining, the tendency for gulls to remain sitting on the nest is very high (baerends 1959). an earlier study of ptarmigan hens (pulliainen 1978) showed that both eggshifting and resettling decreased in frequency during cold periods. differences in energy household during incu bation are illustrated by comparison of common eiders, svalbard and willow ptarmigan hens. eiders carry 20y0 fat prior t o incubation (milne 1976; parker unpublished), svalbard ptarmigan hens less than lw/o fat (mortensen et al. 1983) a n d willow ptarmigan hens less than 2% fat (gramrneltvedt 1978). the eiders d o not feed throughout the incubation period but rely on two sources of energy, the skeletal muscles and body fat. these energy resources are used during the incubation period, causing a 30-45% loss of body weight (milne 1976; korschgen 1977; parker unpublished). both wild and captive ptarmigan hen< eat somewhat throughout the incubation period. however, both species lose about 2p/o of their body weight during incuba tion. svalbard ptarmigan hens receive one less meal per day compared to willow ptarmigan hens. less energy input per day in svalbard ptarmigan hens was partly compensated for by less energy used for locomotion, foraging and re-heating the eggs. svalbard ptarmigan hens, in contrast to willow ptarmigan hens, store body fat as an energy reserve to be used during incuba tion. because willow ptarmigan hens have little or no body fat prior to incubation they are more vulnerable to periods of fasting. in willow ptar migan hens the energy content of one less meal per day would have a total negative effect of 14 kcal/day, energy which would have to come mainly from body protein. both willow and svalbard ptarmigan hens incubate eggs of the same average weight. they show the same reduction in food intake and the same loss of body weight. the only major diffe rence is that svalbard ptarmigan hens use body fat as an energy reserve during incubation. such fat reserves enable the hen t o increase nest atten tiveness while at the same time reducing energy expenditure d u e to lowered activity and less re heating of the eggs. more precipitation falls in troms county, but the ambient temperature is lower in svalbard. the low ambient temperature is suggested to be the most important factor sti mulating the high nest attentiveness in svalbard ptarmigan hens. slagsvold’s (1975) analysis of previous willow ptarmigan data showed a posi tive correlation between ambient temperature at the end of the incubation period and the produc tion of chicks. steen & unander (1985) conclud ed that the physical condition of svalbard ptar migan hens prior to breeding seemed to be the most important factor in determining chick pro duction. in a study of willow ptarmigan hens at dovre (62 o n), erikstad ( 1 985) showed that hens in good condition took fewer recesses than hens in poor condition. however, differences in incu bation behaviour did not influence hatching success. for ptarmigan hens, a high rate of nest attendance is dependent upon sufficient internal reserves and food intake. low ambient tempera tures and much precipitation during the incuba tion period may hasten the drain of reserves and limit food intake, thereby weakening hens and indirectly influencing chick production. 69 acknowledgements. we are grateful to dr. howard parker for his help during our field work at karlsoy. we also want to thank dr. parker, dr. johan b. steen and two anonymous reviewers for valuable suggestions regarding the manuscript. references aulie, a. 1976: the shivering pattern in an arctic (wil low ptarmigan) and a tropical bird (bantam hen). comp. biochem. physiol. 53a,347-350. baerends, g.p. 1959: the ethological analysis of incu bation behaviour. ibis. 101,357-368. barth, e.k. 1949: redetemperaturen og rugevaner. naturen, 81 -95. biebach, h. 1979: energetik des briitens beim star (sturnus vulgaris). j. ornithol. 120,121 138. biebach, h. 1981 : energetic cost of incubation on dif ferent clutch sizes in starlings (sturnus vulgaris). ardea69,141--142. brisbin, i.l. 1964: bioenergetic of the breeding cycle of the ring dove. auk. 86,54-74. el-wailly, a.j. 1966: energy requirements of egg laying and incubation in the zebra finch, taeniopygia castanatis. london 68.582-594. erikstad, k.e. 1985: relationship between weather, bodv condition and incubation rhythm in willow grouse. ph.d. thesis. univ. of bergen. paper2. gabrielsen, g.w. & steen, j.b. 1979: tachycardia during egg hypothermia in incubating ptarmigan (lagopus lagopus). acta phys. scand. 107,273-277. gessaman, j.a. & findell, p.r. 1979: energy cost of incubation in the american kestrel. comp. biochem. physiol. 63a, 57 -62. grammeltvedt, r. 1978: atrophy of breast muscle with a single fibre type (m.pectoralis) in fasting. willow grouse, lagopus lagopus (l). j . exp. z o k 205(2). 195-204. grant, g.s. & whittow, g.c. 1983: metabolic cost of incubation in the laysan albatross and bonin petrel. comp. biochem. physiol. 74a ( i ) , 77-82. haftorn, s. & reinertsen, r.e. 1985: the effect of temperature and clutch size on the energetic cost of incubation in free-living blue tit (parus caeruleus). auk. 102(3). 470-478. kendeigh, s.c. 1963 : thermodynamics of incubation in the house wren (troglodvtes aedon). proc. h i . ornithol. congr. 13,884-904. kleiber, m. 1975: thefire of life. an introduction to animal energetics. john wiley & sons, inc. new york, london. korschgen, c.e. 1977: breeding stress of female eiders in maine. j . wildl. mgmt. 41,360-373. mertens, j.a.l. 1977: the energy requirement for incu bation in great tits (purus major i,.) ardea 65, 185196. mertens, j.a.l. 1980: the energy requirement for incu bation in great tits and other bird species. ardea 69,184-192. midtgbrd, u., sejrsen, p. & johansen, k. 1985: blood flow in the brood patch of bantam hens: evidence of cold vasodilation. j. comp physiol. b. 155, 703-709. milne, h. 1976: body weight and carcass composition ofthe common eider. wildfowl27,115122. mortensen, a., unander, s., kolstad, m. & blix, a.s. 1983: seasonal changes in body composition and crop content of spitsbergen ptarmigan (lagopus rnutushyperboreus). ornis scand. 14,144148. mortensen, a. & blix, a s . 1985a: seasonal changes in resting metabolic rate and mass-specific conductan ce in svalbard ptarmigan and norwegian rock ptar migan and norwegian willow ptarmigan. ornis. scand. 17,8--13. mortensen, a. & blix, a s . 1985b: seasonalchanges in energy intake, energy expenditure and digestibility in svalbard ptarmigan and norwegian willow piarmi gan. ph.d.thesis. univ. of tromsa paper 6. moss, r. 1973: the digestion and intake of winter foods by wild ptarmigan in alaska. condor 75, 293 -300. moss, r. & hanssen, 1 . 1980: grouse nutrition. nurri tion abstracts and reviews b . 50,550-567. norton, d.w. 1973: ecological energetics of calidri dine sandpipers breeding in northern alaska. diss. abstr. int. b. 34,2267-2268. pulliainen, e. 1978: behaviour o f a willow grouse ( l a gopus 1 . lagopus) on the nest. ornis fennica 55. 141-148. ricklefs, r.e. 1974: energetics of reproduction in birds. pp. 152-292 in paynter, r.a. jr. (ed.): avian energerics. nuttall ornithol. club publ. no. 15. cam bridge,mass. riddle, 0. & brancher, p.f. 1934: studies on the phy siology of reproduction in birds. x x x i i i . body size changes in doves and pigeons incident to stages of the reproductive cycle. a m . j. physiol. 107,343-347. schmidt-nielsen, k. 1975: in animal physiology adap tion and environment. cambridge university press. slagsvold, t. 1975: production of young by the willow grouse (lagopus lagopus (l.))in norway in relation t o temperature. norw. j. zoo123.269-275. steen, j.b. & unander, s. 1985: breeding biology of the svalbard rock ptarmigan (lagopus rnutus hyper boreus). ornis scand. 16,19 1 197. terien, 0., aulie, a. & steen, j.b. 1986: thermoregula tory responses to egg cooling in incubating bantam hens. j. comp. physiol. b. 156.303-307. unander, s., mortensen, a. & elvebakk, a. 1985: crop content of the svalbard rock ptarmigan (lagopus rnutus hyperboreus). polar research 3(2). 239-243. vleck, c.m. 1981 : energetic cost of incubation in the zebra finch. condor 83,229-237. walsberg, g.e. & king, j.r. 1978: the energetic conse quences of incubation for two passerine species. auk. 95,644-655. west, g.c. 1960: seasonal variation in the energy balance of the sparrow in relation t o migration. auk 77,306-329. spatial autocorrelation in marine birds david c. schneider schneider, d . c. 1990: spatial autocorrelation in marine birds. polar research 8, 89-97. all marine organisms exhibit some degree of spatial autocorrelation, which is the tendency for high (or low) densities to occur in proximity, rather than at random in the ocean. autocorrelation occurs at scales ranging from the length of the organism to thousands of kilometres. autocorrelation results from a wide variety of mechanisms, many of which act at characteristic scales. consequently, some insight into causal mechanisms can be obtained from exploratory analysis of the scalc and intensity of autocorrelation of abundance or behaviour, and the scale and intensity (coherence) of cross-correlation with environmental variables such as water temperature or prey abundance. this paper uses seabird counts along extended transects t o illustrate standard measures of autocorrelation and cross-correlation. a brief discussion of exploratory and confirmatory analysis of autocorrelated data on marine birds follows. david c. schneider, ocean science centre, memorial university of newfoundland, st. john’s, newfound land, canada, a i b 3x7; january 1989 (revised august 1989). intuitive measures of autocorrelation prior t o 1980, measurement of seabird abundance and behaviour occurred almost entirely at stations with fixed coordinates, separated by large distances. the unit of measurement was a count standardized by time, by length of a strip transect, or by area of a strip transect (tasker et al. 1984). the method was well suited to large scale surveys (e.g. shuntov 1974; brown et al. 1975), which necessarily sacrificed information on smaller scale heterogeneity (devillers 1978) in the interests of observer alertness. through a fortunate cir cumstance i was able to make spatially continuous counts along hundreds of kilometres of ocean in conjunction with probes, a multi-disciplinary investigation of circulation and biological pro duction in the southeastern bering sea. the for tunate circumstance was the sampling design of probes, which consisted of measurements at stations separated by 25 km along a 500 km tran sect, running from the edge of the continental shelf northeastward toward the coast. by counting continuously between stations, i was able to obtain spatially (though not temporally) con tinuous counts along the hundred or more kilo metres that the ship traversed during the long daylight hours of mid-summer in the bering sea. of course, i soon learned what many previous observers must have noticed, which is that one can expect to see many birds ahead if one sees many birds during the present count, and con versely, few birds ahead if few birds are currently in sight. this meant that one had to exert extra effort when counts were low, the expectation of few birds ahead tending to re-inforce itself through relaxation of attention. after two traverses of the probes line in late may 1980, it also became clear that systematic increases and decreases in bird abundance occurred over distances of tens of kilometres, a pattern that had not been previously reported in marine birds. the pattern in the bering sea was repeatable from year to year. fig. 1 shows the july 1982 distribution of birds along the same transect that was traversed in may 1980, coarse scale (1 t o 100 km) aggregations have now been reported in marine ecosystems as diverse as the california current (briggs et al. 1984), the beng uela current (schneider & duffy 1985), the lab rador current (schneider & piatt 1986), and the agulhas current (abrams & lutjeharms 1988). the bering sea transect could not be analysed by standard techniques for continuous data because of breaks in the series during nighttime transit between stations. the solution that i adopted, working from analogy with the structure of much smaller aggregations (hoffman et al. 1981), was t o assume a characteristic structure for these aggregations attenuation in density with increasing distance from some focal point. the analytic procedure was t o construct filters of vary ing widths, each with the peaked shape of a hypo thetical bird aggregation, slide each filter along the transect, and measure fit of the data to the 90 d. c . schneider (slopel 1 outer i i middle i f f f 0 lo4 1 northern fulmar 40 y 30 e r v) g 20 10 0 700 600 500 400 2 300 m 200 i00 x shear waters il f 1 , , i , i i i f i , , i i ) ( , i 2 4 6 8 10 12 14 16 18 20 22 fig. 1. abundance of fulmars fulmarus glacialis and dark bellied shearwaters, primarily puffinus fenuirosrris, along a 534 km transect, running from the shelf break northeastward across the bering sea toward cape newenham. transect begun 26 july 1982, completed 28 july 1982. redrawn from schneider, hunt & harrison (1986). a stations filter at successive positions along the line. the analysis (schneider 1982) showed good fit (r2 ranging from 77% to 95%) at two fronts, poor fit (r2 less than 77%) along the rest of the transect. this result meant that ten-minute counts (each approximately 3 km long) were autocorrelated at lags (separations) ranging from 1 (adjacent counts) t o 3 (half the observed chord length of an aggregation) near the two fronts. a simple monte carlo analysis, using random rearrangements of the observed ten-minute counts, showed that erroneous identification of structured aggre gations (type i error) by this filtering procedure was small (4%). fig. 2 shows the location of 0.8 t a 0.7 0.6 0.5 y 0.2 o 3 i i ------------d 2 4 6 8 10 12 14 16 18 20 22 24 stations fig. 2. location of structured aggregations along same transect line as shown i n fig. 1. transect begun 31 may 1981, completed 3 june 19x1. delta-t is a measure of change in thermal structure between adjacent stations. redrawn from schneider (1982). structured aggregations of seabirds along the tran sect in june 1981. one extension of this analytic approach is to use a wider variety of filters, guided perhaps by a formal or informal model of patch shape. abrams & lutjeharms (1988) used bell-shaped (gaussian) filters centred o n areas of high sst gradient to examine the relation between seabird abundance and fronts. abrams used a routine from the bmdp package, a considerable savings in effort over the hand computations used in the analysis of the bering sea data. still more sophisticated approaches can be found in the literature on digital filtering (e.g. mendel 1987). a related approach, developed by cliff & ord (1973), is to test whether observed abundances fit a hypothetical pattern of association between counts, whether adjacent or not. this method requires specification of a join structure some a priori pattern of relatedness in space against which to test the data. this technique has proved most useful in the analysis of discrete geographic units of unequal size (such as counties) and readily spatial autocorrelation in marine birds 91 improvement in our analyses by using statistical control t o remove the effects of autocorrelation. intuitively we might anticipate autocorrelation of marine bird counts at separations of tens of metres, because individuals of many species move toward other birds to form loose aggregations at this scale. the same observation leads us to anticipate less autocorrelation at separations beyond the limits of visual contact. these limits might vary from tens of meters for birds sitting on the water to several kilometres for large-bodied soaring species. this observation on seabird behaviour suggests that equation (1) might hold true for marine birds at separations ranging from tens to thousands of metres. an analysis of autocorrelation was carried out with data on the abundance of gliding species along a transect running westward across the lab rador shelf, through a narrow pass with strong tidal currents (gray strait) and then out into hudson strait (fig. 3). turbulence in this passage reaches extraordinary levels. turbulence in gray strait was evident in the motion of the research vessel (css ‘hudson’ c. 7 0 m in length), which lurched laterally as it steamed at 11 knots relative to the water. boils of water as large as the ship rose to the surface around and under the ship as it passed through the strait. birds were observed hovering around these boils, which may have been bringing food to the surface. marine bird concentrations have been reported in straits with turbulent flow in the gulf of maine (braune & gaskin 1982; mercier & gaskin 198.5), on the west coast of scotland (bourne & harris 1979) and in the bering sea (gould et al. 1982). marine specified join structure (such as roads linking counties). the spatial scale of autocorrelation in marine ecosystems one rarely has any basis for specifying a join structure, but one often has enough data to measure the strength of auto correlation between counts as a function of dis tance between counts. in oceanography one needs to know the spatial scale of a phenomenon before one can proceed to estimating rates or investigate underlying processes. one way of determining scale is to ask whether the values of a variable are associated with previous values and over what distances. a correlation coefficient (e.g. the fam iliar pearson coefficient, r) can be calculated at increasingty large lags s to produce a vector of autocorrelations r(s). these numbers can be plot ted against lag to obtain a correlogram. sokal (1979) discusses the use and interpretation of correlograms in ecological contexts. one use of the correlogram is to determine how widely spaced counts need to be in order to be considered spatially independent. one should use separ ations at which r(s) lies ‘near enough’ to zero. correlograms of ecological data often show association at small lags, decaying to negligible association at larger lags. if such is the case, r(s) can be modeled using the exponential decay function: r(s) = e-ks where r(s) is the autocorrelation at lag s , e is the base of natural logarithms, and k is a constant decay rate to be estimated from the data. when s equals zero, r(s) equals one. an appropriate autocorrelation function can be used to filter out autocorrelation within a series (box & jenkins 1976), allowing accurate tests of treatment effects (e.g. ‘more birds here than there?’) with statistical control for autocorrelation of contiguous or closely spaced counts. this is a solution to the problem of ‘pseudo-replication’ (hurlburt 1984), if one can estimate the auto correlation function. how much autocorrelation can be expected in counts of marine birds along extended transects? if strong autocorrelation occurs in distributional data, then we need to worry about its effects on our analyses, and we can expect considerable 90’ 6 0 ° w 60°n 65’ 64-30’w fig. 3. location of 42.9 km transect through gray strait 92 d . c. schneider 4 0 20 table 1 . number o f birds observed along a transect through gray strait on 18 september 1985. transect was 42.9 km long, starting at 1311 hrs. gmt, ending at 1440 hrs. gmt. f glacialis on water ~~ species on water flying f. glacial& 234 r . tridactyla 8 l a m s hyperboreus 0 321 2 113 bird abundance in areas of high turbulence, rela tive to adjacent areas, has not been quantified. counts through gray strait were made on one side of the ship out t o the limit of visibility, which was 100 m in foggy conditions. table 1 shows the species and behaviour of all birds observed along the transect. fig. 4 shows counts of the three most abundant groups fulmars fulmarus glacialis in r tridactyla flying 6o 1 f. glacialis flying fig. 4 . counts of flying birds (fulmars and kittiwakes) and birds on the water (fulmars) along gray strait transect. counting interval of l = 0.3 km used to present data. the air, fulmars on the water and kittiwakes rissa tridactyla in the air. fig. 5 shows the auto correiation of counts at lags from s = 0 to s = 100 (2 km). flying fulmars were more strongly autocorrelated than fulmars on the water and flying kittiwakes. fulmars in the air showed a pattern of autocorrelation at lags close to mul tiples of 5 (100m). this is approximately the diameter of large boils of water upwelling to the surface in the strait, so one interpretation is that fulmars were aggregating in relation to these physical structures. none of the three analyses showed local auto correlation decaying to negligible correlation at distances beyond the limit of visibility. significant autocorrelation occurred at some lags, but no consistent pattern emerged in comparing one species across several transects, or in comparing several species along the same transect. auto correlation was weak (r(s) < 0.3) in the gray strait data. the spatial resolution was 20 m, so it will be interesting to see if weak autocorrelation proves generally true of marine bird counts taken at different spatial resolutions. rather than looking at correlation as a function of increasing lag, one can divide continuous data into a sequence of counts in contiguous intervals, beginning at the interval of minimum spatial reso lution and proceeding to larger intervals. if seabird counts are recorded directly on paper while underway, the minimum practical recording interval is 1 minute, corresponding to a spatial resolution of approximately 300 m at a ship speed of 10 knots (c. 5 m ski). with a computer one can record sightings at temporal resolutions of a second or less t o obtain spatial resolutions of 10 m or less at ship speeds of ten knots. the traditional resolution used in seabird work has been 10 min utes, or roughly 3 km at ship speeds of 10 knots. one consideration in choosing the minimum reso lution interval is that more information can be extracted from high resolution than from lower resolution data. another consideration is that one can always construct lower resolution data (e.g. a sequence of ten-minute counts) from higher resolution data (e.g. a sequence of one minute counts) but not vice versa. a natural step at this point is to ask what happens if one changes the recording interval, either through better instrumental resolution, or as a way of looking at the data. the mean (per count) at any given recording interval can be calculated from the mean obtained at any other spatial autocorrelation in marine birds 93 f. glacialis on water f. glocialis flying r. tridoctylo flying -01 0 01 0 2 03 -01 0 01 0 2 03 0 4 0 5 -01 0 01 0 2 .l l.ll-.a--.li. fig. 5. autocorrelation of flying birds (fulmars and kittiwakes) and birds on the water (fulmars) along gray strait transect. dotted lines are 95% confidence intervals. recording interval. let ni[l] denote the observed count in the ith interval of length l, and let n[l] denote the mean of the ni[l] counts. explicitly, , m n[l] = ni[l] m i z 1 where m is the number of intervals of length l in a transect of length t. if lo is the length of the minimum observable interval, then it can be shown that nil,] = 1 "l] n (3) where n = l/lo, the number of minimum reso lution intervals within an interval of length l. quantities l , l,, and t have the same units, such as kilometres. equation (2) states that from any set of observations ni[l], one can infer the mean count at intervals of any other length. what about the variance calculated at scale l, nz[l]? this quantity, like n[l], is a function of l: -nz[l1 var(ni) i = 1 to tl-' n (4) this quantity, unlike the mean n[l], cannot be rescaled to a constant. however, we do find that we have computed a familiar quantity, the mean squared variance among groups, msamong: l m r n l i = l var(ni) =-x (ni[l] to see what happens when we change interval length l, we can begin with a transect of length t marked off into intervals of minimum resolu tion, lo, then calculate the variance at this scale, n2[lo]. we can then group adjacent intervals into pairs to obtain intervals of length l = 2lo. the variance at this scale, n2[2lo] is: n2[2] = var(nkft + nfght) i = 1 to tl-' ( 6 ) where npft symbolizes counts on the left side of pairs and nfght symbolizes counts on the right side of pairs. consequently, n2[2l0] = var(npft) + var(nf'ght) + 2rl,var(nyr) var(nfght) (7) where rlr is the correlation between adjacent (left and right) subintervals. dividing this equation by n, we obtain: m s a m o n g = m s w i t h i n + 2rl,n-'var(n!,eft)var(nfght) (8) 94 d. c. schneider from this equation we see that if adjacent subintervals (left and right) are not correlated, then rlr will be zero and the variance at the scale of intervals (msamong) will be the same as the variance at the scale of subintervals (mswlthln). if adjacent subintervals are positively correlated, then variance at the scale of intervals (msamong) will exceed variance at the scale of subintervals (mswlthln), depending on the strength of corre lation, rlr. if adjacent subintervals are negatively correlated, then the variance at the scale of inter vals will be less than the variance at the scale of subintervals. this can be generalized to larger subintervals by grouping adjacent pairs to obtain intervals of l = 4l0, grouping these pairs to obtain intervals of l = 8lo, etc. we obtain a similar result if we use the variance to-mean ratio at successively larger intervals because: n*[l] i”l] = “li n*[l] “lo1-i --. n scaling of the variance to the mean in this fashion produces a statistic that, in theory, will not vary with change in scale l as long as counts are independent (not autocorrelated), in practice, some systematic change in i’[l] with change in l can occur because of increase in bias (reed 1983), as the number of intervals (m = tl-’) decreases (l increases). in working with seabird counts, my experience has been that this problem is serious enough to preclude attempts to estimate the true value of i’[l], but not serious enough to preclude plotting i‘[l] against l to look at scale-dependent structure in abundance of birds along transects. not all measures of variability have the property of being theoretically independent of l if counts are independent (uncorrelated with themselves). the measure of variability advocated by green (1979), for example, varies with l when random numbers are used. to obtain an idea of the spatial scale at which chord length of a patch. this is the contiguous quadrat method of greig-smith (1952), which was modified for line transect by kershaw (1957). the contiguous grouping method has been used to examine the scale of variability of seabird counts (schneider & duffy 1985) and to show that cor relation between alcid abundance and capelin prey changes with spatial scale (schneider & piatt 1986). fig. 6 shows the results of contiguous grouping of the kittiwake data from the gray strait transect. more birds were observed in the strait than on either side; this shows as an increase in variability at grouping intervals of more than half an hour, equivalent to interval lengths of 8 km or more. we began by thinking about change in varia bility with increase in the length of the counting interval. we then plotted a measure of variability, the variance-to-mean ratio, among contiguous intervals. the abscissa is the bin size, or frame size: 1 minute count, 5 minute count, 10 minute count, 20 minute count, etc. (fig. 6). we can think about the abscissa of this plot in another way. it is a measure of the frequency of counts along a transect of fixed length. for a 16km transect we have 1/16, 2/16, 4/16, etc. what we have done is to have plotted variability against frequency, with high frequencies on the left, low frequencies on the right. the jargon term for this operation is ‘working in the frequency domain’. the contiguous grouping method (where stat istics are calculated in the frequency domain) is related to spatial autocorrelation (which is cal culated as a function of separation) through the 8 0 0 8 i i m m l . o variability is concentrated, one can plot the vari ance among groups against the length of the 0.02 0.08 0.32 1.28 5.12 20.48 counting interval, l. one expects variability to correlated). one expects variability to increase until one reaches the interval roughly equal to the bin size (km) be unchanged if counts are independent (not autofig. 6. variability, as measured by the variance-to-mean ratio i’[l], of kittiwakes on gray strait transect. l is grouping inter val. spatial autocorrelation in marine birds 95 periodogram i(w), which uses periodic functions to describe variability as a function of the fre quency of grouping (w) within the set of data. the contiguous grouping method of greig-smith results in a periodogram constructed from square waves (ripley 1978). the correlogram r(s) and the periodogram i(w) are related via the fourier transform (cf. ripley 1981). after obtaining a plot of variability as a function of scale, one naturally asks whether the plot can be reduced to some simple functional expression, in much the same way that one approached the correlogram. the statistical literature warns us, however, that the periodogram i(w) is a poor estimator of the underlying continuous function, which is called the spectral density. better results can be obtained (given certain conditions on the data) by using a filter to compute a smoothed estimate of the spectral density. one can also estimate the cross-spectra between two series to obtain the coherence h(w), which is a measure of association between the two series at frequency w. much of the art in performing this sort of analysis comes in choosing the filter. the result, a spectral analysis, is a sophisticated version of the contiguous grouping method of greig-smith (ripley 1978). in a comparison of several dif ferent methods of analysing transect data, ripley (1978) found that spectral analysis seems to be the most reliable method for detecting a pattern. platt & denman (1975) discuss the use of spectral analysis in ecology. an extensive catalogue of other spatial methods can be found in upton & fingleton (1985). a mathematical review of spatial methods can be found in ripley (1981). diggle (1983) covers tests of randomness in spatial data and the construction of stochastic models. exploratory and confirmatory analysis in the abstract, spectral analysis and lagged auto correlation analysis are closely related. in practice, spectral analysis can usually tell us more about the data at hand than analysis on the auto correlation side (tukey 1970). to illustrate this point, we can compare autocorrelation analyses of the gray strait data to spectral analyses of the same data. fig. 7 shows the spectral density of counts of fulmars on the water, fulmars in the air and kittiwakes in the air. in the plot of the data (fig. 4) we see large scale variability in abundance associated with passage into and out of gray strait. we can see that substantial variability exists at smaller scales, but we cannot compare species with respect to this variability at these scales. autocorrelation analysis (fig. 5) shows that fulmars and kittiwakes differ in patterns of smaller scale variability and that fulmars in the water differ from flying birds with respect to smaller scale variability. the plot of auto correlations (fig. 5) gives no sense of the larger scale variability in abundance, or how this com pares with the smaller scale variability. we could plot the autocorrelations at lags up to half the length of the series, but such a plot, with over 1,000 correlation coefficients, is not an informa tive way of summarizing the data for examination. in fig. 7 we see that all three groups flying kittiwakes, flying fulmars, and sitting fulmars exhibit more variability at spatial scales greater than 1 km than at smaller scales. we also see a second concentration of variability at scales on the order of 100m in flying kittiwakes and fulmars, but not in fulmars on the water. at the smallest scale, less than 5 0 m , we see a con centration of variability in fulmars, both on the water and in the air. these patterns are not evi dent in the autocorrelation analyses, which are less effective at summarizing the variability in data through a range of scales. an interpretation of the gray strait transect can now be offered along the following lines: two surface feeding species, kittiwakes and fulmars, were found at higher concentrations in turbulent waters of the strait than in adjacent, less turbulent distance (m) 800 200 100 80 60 40 / nf 0 010 020 030 040 0 50 frequency fig. 7. spectral analysis of flying birds (fulmars and kittiwakes) and birds on the water (fulmars) observed along gray strait transect. the smoothing window (bandwidth = 0.2) was tri angular. 96 d. c . schneider water. in addition, flying kittiwakes and fulmars showed spatial variability at the scale of large boils of water rising to the surface. fulmars were abundant on the water, which suggests that birds were feeding and that the boils were bringing food to the surface. fulmars on the water did not retain the same spatial structure as birds in the air, possibly due to passive transport of birds toward convergences at the edge of boils. this inter pretation focuses on interactions between pre dators and prey in relation to the physical struc ture of the environment rather than on inter actions between groups of birds. cross-spectral analysis showed a positive association between each of the three groups at spatial scales greater than 1 km, no association (positive or negative) between any of the three groups at smaller spatial scales. interactions between species do not appear to be an important source of variation in the abundance of kittiwakes and fulmars along this transect. this analysis illustrates two related ideas. the first is that we need to distinguish between an exploratory approach and a confirmatory approach to data. exploratory analysis, such as the gray strait study, is a matter of discovering what the data have t o tell us. confirmatory analy sis, such as the identification of structured aggre gations along the probes lines, is a matter of circumscribing what we can say with certainty. in this latter analysis the data were not used to construct the model, which was developed from prior surveys of the transect. in the gray strait analysis we could have used confirmatory pro cedures to test the a priori expectation of more birds in the strait than in adjacent waters. however, analysis of the smaller scale variability was entirely exploratory, with concepts being developed from investigation of the data at hand. related to this distinction between exploratory and confirmatory analysis is the second idea, which is that some techniques work better in exploratory than in confirmatory settings. spec tral analyses and factor analyses are good examples of techniques that work well in explora tory situations. we also have a large arsenal of confirmatory techniques, such as model fitting, that functions much better as confirmatory than as exploratory techniques. the idea of exploratory analysis, the attitude that this is a legitimate part of data analysis and the idea that some methods are better than others for exploring data have been elaborated by tukey (1986). acknowledgements. -field work aboard the css ‘hudson’ was supported by funds from the newfoundland institute for cold ocean science (memorial university of newfoundland) and the bedford institute of oceanography, dartmouth, ns, canada. field work in the bering sea was supported by grants dpp7910386 and dpp8206036 from the national science foun dation, washington, d.c. free computing time was provided by the zoology department at the university of rhode island (kingston, ri. usa) and by computing services at memorial university of newfoundland (st. john’s, canada). travel to norway was provided by grants from the nordic council and the troms0 museum. i thank c . bajdik for comments o n the manuscript. this is ocean science centre contribution 34. references abrams, r. w. & lutjeharms, .i. r. e . 1988: relationships between seabirds and meso-scale hydrographic features in the agulhas current retroflection region. proc. xixlnternat. ornithol. congr., 991-996. bourne, w . r. p. & harris, m. p. 1979: birds of the hebrides: seabirds. proc. roy. soc. edinb. 7 7 8 , 445475. box, g . e. p. & jenkins, g. m. j . 1976: time series anulysis: forecasfing and control. holdcn-day. san francisco. 575 pp. braune, b. m. & gaskin, d. e. 1982: feeding ecology of non-breeding populations of larids off deer island, new brunswick. auk 99, 67-76. briggs, k . t., dettman, k. f.. lewis, d. b. & tyler. w. b. 1984: phalarope feeding in rclation to autumnal upwelling off california. pp. 51-62 in nettleship, d. n., sanger. g. a . & springer, p. f. (eds.): marine birds: their feeding ecology and commercial fisheries relationships. canadian wildlife service, ottawa. brown, r. g. b.. nettleship, d. n., germain, p.. tull. c. e. & davis, t. 1975: atlas of eastern canadian seubirdr. canadian wildlife service. ottawa. 220 pp. cliff, a . d. & ord. j . k . 1973: spatial autocorrelation. pion. london. devillers, p. 1978: patchiness of scabird distribution and the shortcomings of sampling methods. ibis 120. 125. diggle, p. j . 1983: sfatistical analysis of spatial point patterns. academic press, london. 148 pp. gould, p. j . , forsell, d . & lensink. c. 1982: m a g i c distri bution and abundance of seabirds in the gulf of alaska and eastern bering sea. us fish and wildlife service. washing ton, d.c. 294 pp. green, r. h . 1979: sampling design and statistical methods for enuironmental biologists. wiley, new york. greig-smith, p. 1952: the use of random and contiguous quad rats in the study of the strueturc of plant communities. annals of botany 16, 293-316. hoffman, w., heinemann, d . & wiens, j . 1981: the ecology of seabird feeding flocks in alaska. auk 98. 437-456. hurlburt, s. h . 1984: pseudoreplication and the design of ecological field experiments. ecol. monogr. 54, 187-211. kershaw, k. a. 1957: the use of cover and frequency in the detection of pattern in plant communities. ecology 38, 291 299. mendel, j. m. 1987: lessons in digital estimation theory. prentice-hall, englewood cliffs, nj. mercier, f. m . & gaskin, d . e. 1985: feeding ecology of migrating red-necked phalaropes (phalaropus lobatus) in spatial autocorrelation in marine birds 97 the quoddy region, new brunswick, canada. can. j . zool. platt, t. & denman, k. l. 1975: spectral analysis in ecology. ann. rev. ecol. syst. 6, 189-210. reed, w. 3. 1983: confidence estimation of ecological aggre gation indices based on counts a robust procedure. bio metrics 39, 987-998. ripley, b . d . 1978: spectral analysis and the analysis of pattern in plant communities. journal of ecol. 66, 965-981. ripley, b . d . 1981: spatial statistics. academic press, new york. 252 pp. schneider, d. c. 1982: fronts and seabird aggregations in the southeastern bering sea. mar. ecol. -progr. ser. 10.101-103. schneider, d. c. & duffy, d. c. 1985: scale-dependent varia bility in seabird abundance. mar. ecol.-progr. ser. 2 5 , 211 218. schneider. d. c. & piatt, j . f. 1986: scale-dependent cor relation of seabirds with schooling fish in a coastal ecosystem. mar. eco1.-progr. ser. 32, 237-246. schneider, d. c., hunt, g. l., jr. & harrison, n . m. 1986: mass and energy transfer to pelagic birds in the southeastern bering sea. cont. shelf res. 5 , 241-257. 63, 1062-1067. shuntov, v. p. 1974: seabirds and the biological structure of the ocean. national technical information service, springfield, va, usa. sokal, r . r . 1979: ecological parameters inferred from spatial correlograms. pp. 167-196 in patil, g. p. & rosenzweig, m. l. (eds.): contemporary quantitative ecology and related ecometrics. statistical ecology series 12. international co operative publishing house, fairland, md., usa. tasker, m. l., hope-jones, p., dixon, t. & blake, b. f. 1984: counting seabirds at sea from ships: a review of methods employed and a suggestion for a standardized approach. auk 101, 567-577. tukey, j . w. 1970: some further inputs. pp. 16?-174 in merriam, d . f. (ed.): geostatics: a colloquium. plenum press, new york. tukey, j. w. 1986: the collected works of john w . tukey. volumes 3 and 4. wadsworth & brooks/cole advanced books and software, monterey, california, usa. upton, g. j . g. & fingleton, b . 1985: spateal data analysis by example. vol. i . point pattern and quantitative data. john wiley, chichester. response of arctic ecosystems to climate change: results of long-term field experiments in sweden and alaska gaius r. shaver & sven jonasson long-term field experiments at abisko, sweden, and toolik lake, alaska, reveal both similarities and differences in response of contrasting arctic ecosystems to changes in temperature, light, and nutrient availability. five different ecosystems were manipulated for 5-15 years by increasing air temperature with greenhouses, by decreasing light with shading, and by increasing available n and p with fertilizers. the ecosystems at abisko included evergreen-dominated heath and fellfield sites; at toolik lake they included wet sedge tundra, moist tussock tundra, and dry heath tundra. in all ecosystems, fertilizer treatment increased plant growth, production, and/ or biomass. plant responses to warming were smaller and occasionally nonsignificant. responses to shading were generally nonsignificant after 3-6 years, although after 9 years the tussock tundra showed significant decreases in biomass. in general, the ecosystems at abisko were less responsive to nutrients and more responsive to temperature than the ecosystems at toolik lake. overall, though, the sites were quite similar in their responses to the perturbations, increasing our confidence in predictions of response to climate change over large areas based on small-area studies. gaius r. shaver, the ecosystems center, marine biological laboratory, woods hole, massachusetts 02543, usa; sven jonasson, dept. of plant ecology3 university of copenhagen, 0. farimagsgade 2 0 , dk-1353, copenhagen k, denmark. introduction arctic ecosystems have the potential for signifi cant feedbacks on global climate change, through changes in their net c balance which affect atmospheric coz and methane content, and through changes in species composition and plant cover which affect surface energy balance and hydrology. some of these feedbacks may already be occurring, as shown for example by recent evidence of c losses from alaskan tundra ecosystems during the warm years of the 1980s and early 1990s, with smaller losses or net c accumulation in the cooler, wetter mid-1990s (vourlitis & oechel 1999). simulation models of the arctic region also predict changes in c fluxes in response to climate, although the predictions are often smaller than expected by extrapolation from short-term process studies (e.g. mckane et al. 1997a). a major difficulty in predicting feedbacks on climate change from the arctic as a whole is that current models simulate the arctic as consisting of only one or a few similar ecosystem types, yet we know that variables like net primary produc tion differ by more than two orders of magnitude within this region (bliss et al. 1981). the major classes of arctic vegetation, including tundra, polar desert and semidesert, differ dramatically in their plant functional type composition, and the accumulation of organic matter in arctic soils varies similarly (jonasson & shaver in press; shaver & jonasson in press). a key issue for improving predictions of feedbacks on global change, therefore, is improving our understanding of how different arctic ecosystem types might respond to broad, regional changes in climate. our ability to generalize about responses of arctic ecosystems to climate change has been improved recently by the completion of several shaver & jonasson 1999: polar research 18(2), 245-252 245 multiyear, whole-ecosystem experiments. while not identical in design, these experiments in volved comparable manipulations of key variables like light, temperature and water and nutrient inputs. their general aim was to evaluate the responsiveness of contrasting ecosystems to change in these variables. the same variables are expected to change as part of global climate change, through warming of the atmosphere, changes in cloudiness, and effects of temperature or precipitation on rates of nutrient cycling (chapin et al. 1995). the experiments were not intended as simulations of specific scenarios for climate change, however. their primary value is through the insights they provide into relative importance of major climate-related controls over these ecosystems, and interactions among these controls over time. this paper summarizes results from experi ments in tundra ecosystems at abisko, sweden, and toolik lake, alaska (chapin et al. 1995; shaver et al. 1998; jonasson, michelsen et al. 1999), where experimental designs were similar and the measured responses were often directly comparable. other multiyear experiments with similar design include those in svalbard and in subalpine vegetation near abisko (wookey et al. 1993; parsons, welker et al. 1994; potter et al. 1995; jonasson, lee et al. 1996; press et al. 1998; robinson et al. 1998), and the international tundra experiment (itex; henry & molau 1997; arft et al. in press). sites and experiments toolik lake and abisko are at similar latitudes (68’38” and 68”20’n, respectively) but are widely separated in longitude (149”34’w versus 18’30’e). elevation at the toolik site ranges from 730-780m, and at abisko from 400-1150m. vegetation at both sites includes diverse tundra types (table 1). at toolik, the ecosystems subjected to manipulation were (1) a wet sedge tundra consisting mainly of rhizomatous sedges, (2) a moist tussock tundra including sedges and deciduous and evergreen shrubs, and (3) a dry lichen-evergreen heath. at abisko the ecosystems included a heath and a fellfield, both dominated by the evergreen cassiope tetragona. temperature, light and nutrient availability were manipulated similarly. air temperature was increased with clear polyethylene greenhouses. at toolik these were approximately 3 x 5 m, 0.5 m high at the sides and 1 m high in the centre, while at abisko they were 1.2 x 1.2 m with the poly ethylene reaching either to the ground or to 5 10 cm above-ground (raising temperatures to two different levels at abisko). light was manipulated by shading, with greenhouse shade cloth at toolik (3 x 5 m frames) and with hessian at abisko (1.2 x 1.2m frames). nutrients were added as granular fertilizer (toolik) or dissolved in water (abisko). at toolik the rates of addition were 10 g m-’y-’ n and 5 g m-’y-l p (except in the first year when 10 g mp2 p were added). at abisko table 1. vegetation characteristics at the study sites. original data in shaver & chapin (1992), chapin et al. (199% shaver et al. (1998), and jonasson, michelsen et al. (1999). above-ground above-ground vascular npp vascular biomass site tundra type plant functional types dominant species (g m-’y-’ (g m-’ toolik moist tussock tussock-forming sedges, lake evergreen and deciduous dwarf shrubs, mosses wet sedge rhizomatous sedges, mosses lichen-heath evergreen and deciduous dwarf shrubs, lichens abisko heath evergreen dwarf shrubs, mosses fellfield evergreen and deciduous dwarf shrubs, mosses eriophorum vaginatuni, 140 800 ledum palustre, vaccinium vitis-iduea, betulu nana eriophorum spp, carex 60 60 vp. ledum palustre, betula nana cassiope tetragona, n.d. 600 vaccinium spp., empetruni hermaphroditurn polaris, salix herbacea loisleuria procumbens, 40 100 cassiope terragonu, salix n.d. 200 246 response of arctic ecosystems to climate change the rates were 4.9 g m-' n and 1.3 g m-' p in the first year and 10 g m--2y-1 n and 2.6 g m-*y-' p in succeeding years. fertilizer addition at abisko also included 9.0 g rn-'y-' k and 0.8 g m-'y-' mg. the greenhouse and shade treatments were maintained annually from soon after snowmelt to late august or early september; fertilizers were added each year after snowmelt except in the year of the principal harvest (1993) at abisko. effects of these treatments have been described elsewhere (havstrom et al. 1993; jonasson, havstrom et al. 1993; chapin et al. 1995; michelsen et al. 1996; graglia et al. 1997; shaver et al. 1998). in general the treatments produce the intended effects. greenhouses warmed the air by 2.5-5.0"c and the soil (at 4 cm) by 0.4-2.0°c, with greater warming in closed greenhouses than in those with a gap at the soil surface. at toolik, which is underlain by permafrost, annual soil thaw was increased in the greenhouses from 38 to 43 cm. shading reduced photosynthetically active photon flux by 50%, and the fertilizer increased n and p inputs to at least 10 times the initial annual uptake requirements of the vegetation. the major confounding effect was the reduction in photon flux in the greenhouses by about 10% at abisko and up to 30% at toolik (the difference was due to the thickness of the polyethylene). mckane et al. (1997b) simulated the effects of the greenhouse warming without this reduction in light and concluded that the net c losses in the greenhouse at toolik were increased due to reduced c fixation at lower light. additional effects of the green houses, such as those due to reduced uv-b irradiance (bjorn et al. 1998), were not studied. the experiments began in different years and were sampled after different periods. treatment of tussock tundra at toolik began in 1981, with harvests in 1982, 1983, 1984, 1989 and 1995 (after 2, 3, 4, 9 and 15 years). treatments in other ecosystems at toolik began in 1989, with harvests in wet sedge tundra in 1994 (6 years) and lichen heath in 1996 (8 years). at abisko, treatments began in 1989 with a harvest in 1993 ( 5 years) and a second harvest in 1998 from which results are not yet available. responses: plant species and vegetation overall responses to the treatments were similar in all five ecosystems (table 2). fertilization with n and p consistently caused the largest changes, increasing primary production and total or above ground biomass. temperature responses were next in magnitude, with smaller increases in production or biomass of vascular plants with higher tem peratures. the temperature response was similar in magnitude to the fertilizer response only for total vascular and evergreen biomass in the abisko fellfield, where evergreens responded strongly to warming while other plant forms responded more strongly to fertilizer (jonasson, michelsen et al. 1999). (the evergreen vuccinium vitis-idaeu responded most strongly at abisko [graglia et al. 19971 and was also the only species to increase in response to warming in moist tundra at toolik lake [chapin et al. 1995.1) moss biomass either decreased or was unaffected by the warming at all sites. shading had the least effect on production and biomass, causing a reduction only after 9 years at 50% light in the tussock tundra (vascular plus nonvascular plants) and after 8 years in the lichen heath at toolik lake (vascular plants only). the production and biomass changes in these experiments are consistent with the hypothesis that nutrient availability is the principal limiting factor in all five ecosystems, and that temperature and light are only secondarily limiting over the 3-15 years of sampling. this conclusion is also consistent with the changes in overall vegetation n and p mass and concentration that were observed (table 2). in the fertilizer treatments, increases in production and biomass were accom panied by increases in both n and p mass and n and p concentration. in the greenhouse treatments where production and biomass increased, there were only small increases in n and p mass, and n and p concentration often decreased. in the shade treatments where production and biomass de creased, n and p mass either did not change or decreased less than production or biomass, so concentration increased. in wet sedge tundra at toolik and at both abisko sites, biomass and n and p mass actually increased (nonsignificantly) with shading. the greatest difference between the toolik and abisko sites was in their temperature response and especially in the temperature x fertilizer interac tion (table 2). increases in production and biomass in the greenhouses were greater at abisko, and at abisko the individual temperature and fertilizer responses were additive when these treatments were combined in both the heath and the fellfield (jonasson, michelsen et al. 1999). shaver & jonasson 1999: polar research 18(2), 245-252 247 t ab le 2 . s um m ar y of v eg et at io n an d so il re sp on se s to th e ex pe ri m en ta l t re at m en ts a t a bi sk o, s w ed en , a nd t oo li k l ak e, a la sk a. u pw ar dpo in ti ng a rr ow s in di ca te in cr ea se s. d ow nw ar dpo in ti ng ar ro w s in di ca te d ec re as es in t he i nd ic at ed v ar ia bl es . v eg et at io n va ri ab le s: n pp = a bo ve -g ro un d va sc ul ar n et p ri m ar y pr od uc ti on ; b io m as s = li ve v as cu la r bi om as s in cl ud in g ab ov egr ou nd pa rt s, ro ot s an d be lo w -g ro un d st em s at a bi sk o, a nd a bo ve -g ro un d pa rt s an d be lo w -g ro un d st em s on ly a t t oo li k l ak e; n m as s an d p m as s = to ta l n a nd p m as s in li ve v as cu la r bi om as s: % n a nd % p = n a nd p c on ce nt ra ti on ( % d ry m as s) i n li ve v as cu la r bi om as s. s oi ls v ar ia bl es : in or ga ni c n = s um o f ex tr ac ta bl e n o 3 an d n h 4: i no rg an ic p = e xt ra ct ab le p 0 4 : n m in = n et n m in er al iz at io n m ur ie d ba g m et ho d) ; m ic ro bi al c , n , an d p = c , n , or p m as s in m ic ro bi al b io m as s. o ri gi na l da ta i n c ha pi n et a l. (1 99 51 , s ha ve r et a l. ( 19 98 ; u np ub l. da ta ), a nd j on as so n, m ic he ls en e t al . (1 99 9) . v eg et at io n s oi ls n p in or ga ni c in or ga ni c m ic ro bi al m ic ro bi al m ic ro bi al t re at m en t s it e t un dr a ty pe n p p b io m as s m as s m as s % n % p n p n m in c n p f er ti li ze r t oo li k l ak e a bi sk o g re en ho us e t oo li k l ak e a bi sk o s ha de t oo li k l ak e a bi sk o g re en ho us e t oo li k l ak e + n p f er t a bi sk o s ha de a bi sk o + n p f er t t us so ck w et s ed ge l ic he nhe at h h ea th f e 1 1 f ie 1 d t us so ck w et s ed ge h ea th f el lf ie ld t us so ck w et s ed ge l ic he nhe at h h ea th f el lf ie ld t us so ck w et s ed ge h ea th f el lf ie ld h ea th f el lf ie ld t tt t ttt tt tt t tt tt t ttt tt tt t i tt ttt t tt t tt tt tt tt t ttt t t t t c 1 x h t u t t t t h tt tt tt tt tt tt tt tt tt tt t ttt tt t t tt t ttt ttt t + -+ tt tt t tt h tt tt tt t tt u u h h i t t c i h h h h h u c i c 1 tt t tt t t tt tt t tt tt tt tt tt tt tt tt tt tt ti t t tt tt tt t t h u t t u t t t u h t u h t u c t t u tt tt h u t tt tt tt tt tt at toolik lake in both moist and wet sedge tundras (chapin et al. 1995; shaver et al. 1998). there was a significant negative temperature x fertilizer interaction, such that production and biomass were lower i n the fertilized and warmed plots than in either individual treatment. further more, at abisko the increases in biomass with warming and with warming plus fertilizer were accompanied by nearly proportional increases in n and p uptake, so the changes in n and p concentration were smaller than at the toolik sites. there are several possible explanations for this difference between sites, but the most likely include: (1) soil temperatures are lower at toolik, which is underlain by permafrost. the effect of warming on nutrient mineralization in the soil (discussed below) may be smaller at toolik than at abisko, leading to a smaller increase in nutrient uptake in the warmed plots, and a smaller increase in biomass. (2) the fertilizer treatment at toolik, with or without warming, fully overcame the initial nutrient limitation so that factors other than nutrients or temperature were limiting to produc tion and biomass in the fertilized plots at toolik. at abisko, however, the fertilizer treatment did not fully eliminate the nutrient limitation, so that additional increases in biomass were possible with warming plus fertilizer. (3) the higher plant n and p concentrations in the warmed plus fertilized plots at toolik may have led to increased respiratory c losses (linked to higher maintenance costs of high-nutrient tissues), which would counter nutrient-stimulated growth increases. air temperatures were also higher at toolik than at abisko, which would lead to even higher respiration rates. in sum, the differences in the temperature responses of vegetation at abisko versus toolik may be tied to differences in temperature effects on soil nutrient mineralization and plant nutrient use, not to the direct effect of temperature on plant c accumulation. at the two abisko sites, there also was a negative interaction between the shade and the fertilizer treatments, such that biomass did not increase above controls when these treatments were combined despite large increases in n and p mass and concentration (table 2). this response indicates that, at least at the low light levels in the shade treatments, the vegetation was unable to take advantage of greater nutrient availability with fertilization. the greatest differences between abisko and toolik were changes in species composition that had no clear impact on vegetation biomass or nutrient mass. in particular, the fertilizer treatment had a major impact on species composition at toolik but relatively little impact at abisko. in the tussock tundra at toolik, by the ninth year of treatment the vegetation was dominated (65% of vascular biomass) by the deciduous shrub betula naizn. a species that accounted for only 25% of biomass in control plots (chapin et al. 1995). by the 15th year the tussock vegetation was over 90% b. nana. although b. nana also grows at the abisko heath site, it did not respond strongly to fertilizer treatment there (graglia et al. 1997). similarly, the lichen-heath at toolik responded to fertilizer addition by essentially complete replace ment of the dominant evergreens with the grass hierochloe alpina. at abisko the species compo sition of both sites did change slightly with fertilizer treatment (e.g. forb plus graminoid biomass increased) but the dominant species (cassiope tejragona) remained dominant. fertili zer experiments at other sites near abisko, however, have shown greater increases in grasses or sedges (jonasson 1992; parsons, press et al. 1995). in the longer term the changes in species composition in the toolik sites may cause a divergence between toolik and abisko in their responsiveness to the experimental treatments. at toolik the wet sedge, lichen-heath and tussock tundras have been followed for 6, 8 and 15 years, respectively. preliminary results from 10 years of treatments at the abisko heath site show a similar pattern of response to that seen after 5 years, but with a stronger increase in the deciduous dwarf shrub vaccinium uligiiiosum in warmed plots (a. michelsen, unpubl. data). because all of the dominant species in these communities are long lived, with large amounts of slowly-replaced stem, leaf and below-ground biomass, there may be a considerable lag before changes in growth are fully reflected in changes in biomass (chapin et al. 1995; jonasson 1997). changes in species composition in response to warming or fertilizer addition in the low arctic also differ from the high arctic. at toolik lake where there is little bare ground, species richness was consistently reduced due to loss of herb shaver & jonasson 1999: polar research 18(2), 245-252 249 species that are minor contributors to biomass and production (chapin et al. 1995; shaver unpubl. data). in svalbard where bare ground is available for colonization, species richness increases with fertilizer addition (robinson et al. 1998). on the other hand, cover of dryas octopetala in fertilized and watered plots in svalbard was reduced after a wet and mild growing season, probably because of delayed winter hardening associated with the treatment (robinson et al. 1998), suggesting that extreme climatic events can cause pronounced stepwise changes in the communities. responses: soil nutrients and microbes the fertilizer treatments increased inorganic n and p pools at toolik and the abisko fellfield, even as plant uptake and microbial immobilization also increased (table 2). the magnitude of these changes was smaller, though, at abisko, and in the heath at abisko there was no change in inorganic n (jonasson, michelsen et al. 1999; schmidt et al. 1999). the lack of a fertilizer effect on inorganic n at the abisko heath, combined with the increases in vegetation biomass, n mass and p mass, suggests that vegetation was still a strong nutrient sink even after 5 years of treatment, and was still capable of reducing available soil n to the level of unfertilized soil. the large accumulations of inorganic n in the other sites, particularly at toolik, suggest that they were becoming nutrient saturated. the shade and greenhouse treatments had different effects on inorganic n and p pools at toolik versus abisko (table 2). at toolik there was no response to either treatment, while at abisko both inorganic pools increased with shading, as did inorganic p and, to a lesser degree, inorganic n, with warming. the responses to shade reflect continued vegetation nutrient uptake at toolik despite reduced productivity there, and perhaps reduced uptake at abisko. the responses to warming are more complex and probably represent different combinations of increased vegetation uptake and increased n and p miner alization with warming. the fact that vegetation biomass, n mass and p mass consistently in creased with warming at abisko even as inorganic n increased in the fellfield and inorganic p increased in the heath suggests that the warming increased mineralization more than it increased uptake there, while at toolik vegetation uptake paralleled the increased mineralization. microbial immobilization clearly did not drive changes in inorganic n and p pools, as microbial c, n, and p pools increased only when the inorganic pools also increased (table 2; data available only from abisko). on the other hand, increases in n mineralization in the greenhouses in the toolik wet sedge tundra did not cause any corresponding increase in inorganic n pools. the most likely explanation for this pattern is that plants are much more effective competitors for inorganic n and p than expected, such that the changes in both soil-available and microbial pools are inversely related to the plant uptake demand (jonasson, michelsen et al. 1999). differences between toolik and abisko in treatment effects on inorganic n and p pools could also be due, in part, to differences in element losses from the treated plots by leaching andlor denitrification. these losses were not measured, although the abisko sites were not underlain by permafrost, so deeper drainage was possible. synthesis clearly, a diverse group of five contrasting low arctic ecosystems on two continents respond similarly when subjected to similar manipulations. this result increases our confidence in predictions of similar responses to climate change over at least the low arctic, that part of the arctic where most of the organic matter, c and nutrients are held. comparable results are still needed from the high arctic, although recent work suggests that these areas should respond in similar ways (robinson et al. 1998). in this regard it is less important that the experiments represent explicit simulations of global change than it is important that the experiments cover a broad spectrum of key variables (nutrients, temperature and light), and that the similarities in response among sites were consistent across the full spectrum of treatments. at the 5-15 year time scale of these experi ments, soil nutrient availability and vegetation nutrient demand are clearly of dominant impor tance. although temperature and light do affect both vegetation and soils, their effects are relatively small at this time scale and clearly interactive with n and p availability. from the 250 response of arctic ecosystems to climate change perspective of the vegetation, it appears that changes in n and p availability can cause large and relatively rapid changes in production andlor biomass even if ambient temperature regimes and light levels are unchanged. the vegetation re sponse to warming is constrained by the plants’ ability to accumulate additional n and p, such that over several years the effects of temperature on soil processes may be more important than direct effects on plant growth. at low light, continued uptake of n and p in amounts similar to control conditions allows productivity to continue at near control rates, so that even at 50% reduction in light it takes several years for a significant reduction in biomass to occur. the importance of nutrient limitation is also reflected in the soils, where the changes in inorganic and microbial nutrient pools are consistent with highly effective plant uptake in relation to temperatureand light-related changes in uptake requirement. additional research is needed to explain the relatively small differences in response that were observed between toolik lake and abisko. but these differences are consistent with the inter pretation that nutrient limitation is dominant at both sites. at the levels of fertilizer that were used, this limitation may have been completely over come at toolik, while at abisko the continued increases in biomass with warming plus fertilizer suggest that higher levels of fertilizer might continue to elicit responses. the greater warming responses at abisko could also be due as much to the effect of temperature on soil nutrient avail ability and uptake as to direct effects of tempera ture on photosynthesis and growth, which is consistent with the changes in plant and soil n and p pools that were observed and with the observation that soils at toolik are wetter and colder at depth, due to permafrost. a final overall conclusion is that long-term (multiyear) changes in the c cycle of arctic ecosystems are tightly linked to changes in the cycles of n and p, and thus it is essential to understand long-term controls over each of these cycles and the linkages between them in order to predict long-term change in organic matter cycling. clearly, there must be a correlation between short-term and long-term controls on element cycles, but we need long-term experi ments to understand the mechanisms that deter mine these correlations, and to understand how long-term change is constrained by interactions among element cycles. references arft, a. m. et al. (29 authors) in press: response patterns of tundra plant species to experimental warming: a metaanalysis of the international tundra experiment. ecology. bjorn, l. o., callaghan, t. v., gehrke, c., johanson, u., sonesson, m. & gwynn-jones, d. 1998: the problem of ozone depletion in northern europe. anibio 27. 275-279. bliss. l. c., heal. 0. w. & moore, j. j . (eds.) 1981: tundra ecosvstems: a comparative analysis. cambridge: cambridge university press. chapin, f. s., shaver, g. r., giblin, a. e., nadelhoffer, k. j. & laundre. j. a. 1995: responses of arctic tundra to experimental and observed changes in climate. ecology 76, 69&7 1 1. graglia. e., jonasson, s., michelsen. a. & schmidt, i. k. 1997: effects of shading, nutrient application, and warming on leaf growth and shoot densities of dwarf shrubs in two arctic/ alpine plant communities. ecoscience 4 , 191-198. havstrom, m., callaghan, t. v. & jonasson. s. 1993: differential growth responses of cassiope tetragonu, an arctic dwarf-shrub, to environmental perturbations among three contrasting highand subarctic sites. oikos 66, 389 402. henry. g. h. r. & molau, u. 1997: tundra plants and climate change: the international tundra experiment (itex). global change biol. 3 (suppl. 1 ) , 1-10, jonasson. s. 1992: growth responses to fertilization and species removal in tundra related to community structure and clonality. oikos 63, 420-429. jonasson, s. 1997: buffering of arctic plant responses in a changing climate. in w. c. oechel et al. (eds.): global change and arctic terrestrial ecosystems. pp. 365-380. new york springer. jonasson, s. & michelsen. a. 1996: nutrient cycling in subarctic and arctic ecosystems, with special reference to the abisko and tornetrask region. in p. s. karlsson & t. v. callaghan (eds.): plant ecology in the subarctic swedish lapland. ecol. bull. 45. 45-53. jonasson, s. & shaver, g. r. in press: within-stand nutrient cycling in arctic and boreal herbaceous and forested wetlands. ecology. jonasson, s., havstrom, m., jensen, m. & callaghan, t. v. 1993: in situ mineralization of nitrogen and phosphorus of arctic soils after perturbations simulating climatic change. oecologia 95. 179-1 86. jonasson, s., lee, j. a,, callaghan, t. v., havstrom, m. & parsons. a. n. 1996: direct and indirect effects of increasing temperatures on subarctic ecosystems. in p. s. karlsson & t. v . callaghan (eds.): plant ecology in the sn6arcfic swedish lapland. ecol. bull. 45, 180-191. jonasson. s., michelsen. a., schmidt, i. k. & nielsen, e. v. 1999: responses in microbes and plants to changes temperature, nutrient, and light regimes in the arctic. ecology 80, 1828-1843. mckane, r. b., rastetter, e. b., shaver, g. r., nadelhoffer. k. j., giblin. a. e. & laundre. j. a. 1997a: reconstruction and analysis of historic changes in carbon storage in arctic tundra. ecology 78, 1188-1 198. mckane, r. b.. rastetter, e. b., shaver, g. r., nadelhoffer, k . j . , giblin, a. e. & laundre, j. a. 1997b: climatic effects on tundra carbon storage inferred from experimental data and a model. ecology 78, 1170-1187. shaver & jonasson 1999: p o l a r research / 8 ( 2 ) , 245-252 25 1 michelsen, a., jonasson, s., sleep, d., havstrom. m. & callaghan, t. v. 1996: shoot biomass, i3c. nitrogen, and chlorophyll responses of two arctic dwarf shrubs to in situ shading, nutrient application, and warming simulating climatic change. oecologia 105, 1-12. parsons, a. n., press, m. c., wookey, p. a,, welker, j. m., robinson. c. h., callaghan, t. v. & lee, j. a. 1995: growth responses of calamagrostis lapponica to simulated environ mental change in the sub-arctic. oikos 72, 61-66. parsons, a. n., welker, j. m., wookey, p. a,, press, m. c., callaghan, t. v. & lee, j. a. 1994 growth responses of four sub-arctic dwarf shrubs to simulated environmental change. j. ecol. 82, 307-318. potter, j . a., press, m. c., callaghan, t. v. & lee, j. a. 1995: growth responses of polytrichum commune and hylocornium splendens to simulated environmental change in the sub arctic. new phyrol. 131, 533-541. press, m . c., potter, j. a., burke, m. j. w., callaghan, t. v. & lee, j. a. 1998: responses of a subarctic dwarf heath community to simulated environmental change. j . ecol. 86, 3 15-327. robinson. c. h., wookey, p. a,, lee, j. a,, callaghan, t. v. & press, m. c. 1998: plant community responses to simulated environmental change at a high arctic polar semi-desert. ecology 79, 856-866. schmidt, i. k . , jonasson, s. & michelsen, a. 1999: mineraliza tion and microbial immobilization of n and p in arctic soils in relation to season, temperature, and nutrient amendment. appl. soil ecol. 11, 147-160. shaver, g. r. & chapin, f. s. 1991: productionbiomass relationships and element cycling in contrasting arctic vegetation types. ecol. monogr. 61, 1-31. shaver, g. r. & jonasson, s. in press: productivity of arctic ecosystems. in h. mooney, j. roy & b. saugier (eds.): terrestrial global productivity. new york: academic press. shaver, g. r., johnson, l. c., cades, d. h., murray, g., laundre, j. a,, rastetter, e. b., nadelhoffer, k. j. & gihlin, a. e. 1998: biomass accumulation and c 0 2 flux in three alaskan wet sedge tundras: responses to nutrients, tempera ture, and light. ecol. monogr. 68, 75-99. vourlitis, g. l. & oechel, w. c. 1999: eddy covariance measurements of coz and energy fluxes of an alaskan tundra ecosystem. ecology 80, 686-701. wookey, p. a., parsons, a. n., welker, j. m., potter, j . a,, callaghan, t. v., lee, j. a. & press, m. c. 1993: comparative responses of phenology and reproductive development to simulated environmental change in sub arctic and high arctic plants. oikos 67, 490-502. 252 response of arctic ecosystems to climate change biomass and respiratory ets activity of microplankton in the barents sea rosa martinez martinez. r. 1991: biomass and respiratory ets activity of microplankton in the barents sea pp. 193 200 in sakshaug. e . , hopkins. c. c . e. & 0ritsland. n. a. (cds.): proccedings of the pro mare symposium on polar marine ecology, trondhcim, 12-16 may 1990. p d u r research l o ( / ) . the activity of the respiratory electron transport system (ets) of microplankton was measured in the central barents sea during summer 1988. i n vitro ets activity increased with assay temperature between 0 and 12°c. as reported for other enzyme systems in plankton. the higher in situ activities were observed near the surface (upper 10-25 m) and werc associated with chlorophyll o maxima. respiratory activity in the upper 60 m accounted for 4&w% of the total column respiration. the activities (&lo0 m) were lower than oxygcn consumption rates reported in the canadian arctic, mainly due to lower phytoplankton biomass. they were higher than ets activity measured in the weddcll sea (antarctic ocean). a high detrital versus total microplankton mass accounted for the low activity related to particulatc organic carbon (poc). in general. the levels of respiratory ets activity were in the range reported for temperate oligotrophic oceanic regions. ''@polar\~s<'' rosa martinez. departurnento d e ciencias v t k n i c a s del a g u a . uniuersidad d e canrabria. e-39005 sarrtander, spain (revised june 1991). introduction direct measurements of respiration are scarce compared with the wealth of data on primary production. in contrast to photosynthesis, res piration is a process common to all organisms, and occurs throughout the whole water column. the microplankton fraction has been shown t o be the most metabolically active in different ocean regions (williams 1981; packard & williams 1981; mann 1982; williams 1984; packard 1985a). oxygen consumption by respiration is mostly due to oxidative phosphorylation, driven by the respiratory electron transport system (ets), and the measurement of the activity of this system yields the maximum potential respiration (pack ard 1971, 1985a). data for real-time instan taneous rates of respiratory activity in ocean regions can be obtained through measurement of ets activity. this method facilitates the measure ment of large numbers of samples and the deter mination of very low respiration rates, while avoiding the need for incubations (packard 1985b). both growth and metabolic rates in plankton are limited by low temperatures (packard et al. 1975; neori & holm-hansen 1982). adaptation of organisms to low temperatures can be achieved through biochemical mechanisms. somero (1969) decrease in the ea at near-zero temperatures in cold-adapted marine organisms. chabot (1979) postulated an increase in mitochondria1 oxidation under lower growth temperature, involving enzyme increase. there is no conclusive evidence of these mechanisms in microplankton (packard et al. 1975; li et al. 1984; tilzer et al. 1986). and there are no published data on ets-temperature relationships in arctic microplankton, that could contribute to clarify this question. the central barents sea experiences during the summer oligotrophic conditions, i.e. low chlorophyll a concentrations and nutrient recyc ling (rey & loeng 1985; wassmann 1989; wassmann et al. 1991). therefore, low biomasses and metabolic rates are to be expected. this study was undertaken during the r/v (3.0. sars cruise to the central barents sea in july 1988. its main objective was to provide data on respiratory ets activity in arctic microplankton that can be com pared with ets activity and respiration rates reported from polar and other latitudes, and with primary production and other metabolic rates. study area three stations were chosen which represent three and hochachka & somero (1971, 1973) found a zones in the area: station 1 (73.5"n.. lye), situ 194 rosa m a r t i n e z ated in atlantic water. close to the southern edge of the polar front, with temperatures ranging from -1°c t o 7°c and salinities from 34.5 t o 3 5 ; station 2 (76.7"n, 32.5"e). located at the polar front. in arctic water. with temperatures from -2°c to 1 .@c and salinity from 32.5 to 3 s ; station 3 (72.3"n. 30.5"e), well south of the polar front. perature, t,,, is t h e assay temperature (both in degrees k ) and r is the gas constant. depth-integrated biomass and e t s activity were calculated by integration of single depth values according to the equation: " t ( x ) = e [ c x l ixl+l)/2] * ('i+{ '1) in atlantic water. with coastal water influence (temperature 3°c to 8.2"c, salinity 34.5 t o 34.8). where x, = v a l u e of the variable a t the depth zi. material and methods results microplankton samples were taken at three staenzyme kinetics tions with niskin bottles at 12 to 16 depths, from surface to about 300 m. t h e water samples were screened through a 240 pm net t o eliminate larger zooplankters. filtration was d o n e o n whatman g f / f glass fiber filters. t h e filters with cells were frozen in liquid nitrogen until assaying. 5 to 10 liter samples were filtered for e t s assays, and 290 ml for particulate organic carbon ( p o c ) and nitrogen (pon). chlorophyll a was measured o n board with a turner designs fluorometer using acetone as extractant. nitrate and ammonium were measured on board with a technicon autoan respiratory ets activity increased from 0 to 12°c in the two experiments. t h e mean activation energy for this temperature range, calculated from an arrhenius plot of the results, was 11.5 ? 0.6 kcal mole-'. and this was t h e value used to calculate in situ respiratory rates of all the samples that were routinely assayed at 10°c. q l o for the 0 to 10°c range was 1.6. t h e reaction was linear with time for the first 15min. of incubation a t all incubation tem peratures. consequently, the time used for all the sample incubations was 15 min. alyser, and particulate organic carbon a n d nitro gen were measured with a carlo e r b a c h n biomass and actiuity elemental analyser. the respiratory e t s activity of the samples was analyzed with the packard (1971) and kenner & ahmed (1975) enzyme assay. a time and tem perature kinetics study was performed on two occasions prior to assaying. for this. a large water sample (60 i) was taken from the chlorophyll maximum layer, thoroughly mixed and fractioned in 6 aliquots of 10 1 each, that were subsequently filtered and frozen in the same way as t h e samples. assays were run in duplicate for each aliquot, at 6 different temperatures: 1. 5. 7 , 8, 10 and 12°c. several incubation times were used for each assay: 5, 10, 15, 20 and 2 5 m i n . this was done t o cal culate the enzyme activation energy that should be used when converting activities from a single incubation temperature at which t h e assays were run to in situ activity, according t o the equation table 1 summarises t h e results of biomass and activity variables at t h e three stations. fig. 1 represents the vertical distribution of the biomass variables. t h e m o m zone was considered as the euphotic zone according t o the chlorophyll a distribution. nitrate and ammonium profiles at stations 1 and 2 are shown in fig. 2 (nitrate and ammonium data were unavailable a t station 3). a strong nitracline developed a t 2 m 0 m depth, where nitrate concentrations ranged from zero to 10 mmole nitrate was exhausted at the surface of atlantic as well as arctic waters. chlorophyll concentrations a t stations 1 and 3 were low, corresponding t o the post-bloom stage. the peak of station 1 was situated at the nitra cline, about 25 m , and amounted t o 0.3 mg m-3. station 2 showed t h e features of a bloom situation (rey et al. 1987) with t h e chlorophyll peak located ets(in situ) = ets(assay) at 12 m depth, just above t h e nitracline, although i t represented only 3 mg m-3. mean chlorophyll exp[ed'l'tds' l't's)'r1 a concentration was a n o r d e r of magnitude higher where e, is the activation energy of the enzyme at station 2 (0.58 mg m-3) than station 1 reaction (in kcal mole-'). t,, is the in situ tern(0.059 mg it-^). biomass and respiratory e t s activity of microplankton in the barents sea 195 table 1. mean values of biochemical variables f o r the three stations. variable station mean s . d . min. m a x . n poc (mg m3) pon (mg m i ) chla (mg m 3 ) ets (ml 0 2 m 3 h-i) poc/chla (w/w) (0-100 m) etsichla (m102 mg-' h ' ) (0-100 m) c/n (at/at) c-sp. ets (d-') 1 2 3 all 1 2 3 all 1 2 3 all 1 2 3 all 1 2 3 all 1 2 3 all 1 2 3 all 1 2 3 all 113 142 233 155 13.4 16.7 23.4 17.2 0.06 0.60 0.20 0.29 0.25 0.47 0.51 0.40 2536 342 1404 1424 5.11 0.87 2.39 2.69 12.1 11.4 12.7 12.0 0.027 0.033 0.030 0.030 69 127 106 111 10.8 16.4 10.9 13.4 0.06 0.94 0.22 0.60 0.25 0.78 0.37 0.5 2103 222 i i46 1097 4.01 0.55 0.52 2.50 3.7 2.0 1.4 2.7 0.013 0.020 0.017 0.017 49 54 70 49 4.1 5.5 6.1 4.1 0.01 0.02 0.01 0.01 0.05 0.06 0.17 0.05 1179 105 365 105 0.85 0.23 i .60 0.23 7.4 7.7 10.4 7.4 0.008 0.01 1 0.010 0.008 235 499 41 1 499 39.7 64.2 40.0 64.2 0.20 3.26 0.61 3.26 0.87 3.10 1.23 3.10 6780 814 3406 6780 14.50 2.00 3.12 14.50 19.6 15.8 15.6 19.6 0.048 0.068 0.056 0.068 16 1s 1 1 42 i 6 1s i 1 42 16 is 11 42 16 15 1 1 42 8 9 6 25 8 9 6 25 16 15 11 42 16 15 i 1 42 poc and pon distributions (fig. 1) varied among the stations. at station 1 they showed peaks in the upper 5 0 m , just above the ammonium peaks, with concentrations of 236 and 40mg m-3, respectively. increases i n poc and pon did not show any correspondence with increases in chlorophyll, which implies that they were probably related mainly to microhetero trophs and/or detrital matter. station 2 exhibited the highest single-depth poc and pon maxima, 499 and 64 mg m-3, corresponding to the chloro phyll maximum. maximum poc and pon con centrations at station 3 were 410 and 19 mg m-3, respectively, at 50 m depth, clearly below the chlorophyll maximum, which was located at 20 m. fig. 3 shows in situ ets activity and carbon specific ets activity. the activity was highest in the chlorophyll maximum at the three stations. suggesting that most of the microplankton meta bolic activity takes place in the upper 40 m and is mainly due to phytoplankton (and possibly also to micrograzers). maximum values were 0.9, 1.3 and 3 . l m l o2 m-3 h-', at stations 1, 2 and 3, respectively. minimum activities occurred at intermediate depths (about 100 m) and a slight increase was observed at station 1 near the bottom, probably due to an increase of bacterial biomass. at station 1, ets activity showed good cor relations with poc, pon and chlorophyll (r2 > 0.6). the correlations were highest at sta tion 2: r2 = 0.7 for poc; r' = 0.8 for pon and r' = 0.9 for chlorophyll. at station 3, the activity was only correlated with chlorophyll (r2 = 0.9) and not with poc or pon. (all correlations had p < 0.001). poc and pon were strongly 196 rosa m a r t i n e z 0 1w h e f u ,"m d 300 fir i . depth profiles of the hiomass variahlcs. poc. pon and chloroph!il u ' u = station 1 ; x x = station 2; a-a = station 3 . correlated at this station (r' = 0.97) and chloro phyll-independent, which further indicates that an important proportion of the particulate organic matter was detrital or microheterotrophic. c,/n (at/at) ratios had a mean value of 12. t h e ratios were highest at station 3 . suggesting the existence of more detrital material. significant differences ( p c o . 0 5 ) were found for the c/n ratio between station 3 (all values) and the other two stations. poc/chl ratios were high d u e to the pre dominance of heterotrophic organisms and detritusduring summer. as compared with a poc/ chl ratio of 59 for phytoplankton during the spring bloom (rey unpubl. obser.). in the chloro phyll maximum at station 2. the ratio had a mini fig. -7. dcpth profiles of nitrate and ammonium at stations 1 and 2: c. = station i : x x = station 2 biomass and respiratory ets actiuity of microplankton in the barenrs sea 197 a iaa e v r c n 8 200 fig. 3. depth profiles of ets activity (etsa) and carbon-specific ets activity (c-specific etsa): x-x = station 2; a-a = station 3. 0-4 = station 1; 300 e t s activity, rnl.02rn-’h-’ c-specific e t s activity, h-] mum value of 105, which indicates a moderately high proportion of phytoplankton in the total microplankton biomass. ets activity was converted to carbon units (mg c m-3 h-l), using a respiratory quotient rq = 1 (packard 1979; simpkins 1986; shaffer 1987). the result was divided by poc con centration to find the (potential) carbon-specific respiratory rate, or carbon respiratory turnover, in (time)-‘ units. the carbon respired ranged from 0.02 to 1.4 mg c m-3 h-l (mean = 0.22 mg c m 3 h-l). the carbon-specific rate (fig. 3) ranged from 0.01 to 0.07 h-l and was highest in the chlorophyll maximum, as were both biomass and absolute ets, suggesting that at that depth the living biomass was both more abundant and more metabolically active. depth-integrated values of biomass and actiuity integral column values for the biomass and activity variables are summarised in table 2. sta tion 1 showed the lowest depth-integrated chloro phyll and ets activity. poc and pon were similar at stations 1 and 2 (26 and 23 g c rn-2; 3 and 2.6 g n m-*) and higher at station 3: 43.4 g c m-2 and 4 g n m-?. chlorophyll a was highest at station 2: 61 mg m-2. ets activity showed an increase in the stations 1-2-3 sequence: 0.7, 0.8 and 1.1 g c m-* d-i. c/n ratio (atoms) of the integrated water column was 9 for stations 1 and 2 and 11 for station 3. table 2 also shows the integral values for the 0-60 m water column, and the percentage of the total column contained in it. the distributions of biomass and activity at station 2 were different from stations 1 and 3, table 2. depthintegrated values of biochemical variables. in parentheses. percentage of the total column value contained in the upper 60 m. ~ sta depth poc chl a etsa c/n c/chl ets/chl c s p ( m ) d-i) d-i) ( d l ) no. range (g m-’) (mg m l ) (gc m ? (at/at) (w/w) (gcgchl-’ ets ~ 1 &60 9.3 (35%) 5.5 (52%) 0.27 (39%) 8.2 206 49.0 0.03 0-340 26.4 10.6 0 . 6 9 8.8 2480 62.8 0 . 0 3 2 0-60 9.8 (42%) 54.5 (90%) 0.51 (62%) 7.6 1 80 9.4 0.05 &250 23.3 60.8 0.82 8 . 8 383 14.0 0.04 0-255 43.4 4 . 0 1.10 10.9 1685 42.7 0.03 3 0-60 17.3 (40%) 20.6 (79%) 0.49 (44%) 13.6 840 23.8 0.03 198 rosa martinez which exhibited strongly stratified water masses, and where 45% of poc. 73% of p o n . 89% of chlorophyll and 62% of e t s activity took place above 60 m. ratios between depth-integrated variables (table 2) were calculated for the 6 0 upper m and the total column. t h e euphotic zone of station 2 had the lowest c/n ratio ( 7 . 6 a t / a t ) , chlorophyll specific p o c (180 g/g), p o n (43 g/g) and e t s activity (9.4 g c g chla-' d-i) and the highest carbon-specific e t s activity (5.2% d-i). indi cating that this water mass was the richest in phytoplankton and protein. and the most meta bolically active. discussion the in vitro e t s activity increased with tem perature in the assayed interval (0-12"c), showing a similar effect to that reported for other enzyme systems in cold-water organisms. activation energy (e,) was 11.5 kcal m o l e ' , similar to the e, = 12 reported by neori & holm-hansen (1982) for photosynthesis of antarctic phyto plankton at near-zero temperatures, and lower than the mean value (e, = 16 kcal mole-') found by packard et al. (1975) for e t s activity in mic roplankton from several latitudes. however, tem peratures in their study ranged between 9 and 28°c and did not include polar zones. e, in t h e present study falls in lower part of their range. this suggests that e, in cold-water microplankton is at the lower end of responses t o naturally occur ring temperatures, as postulated for photo synthesis and growth of polar phytoplankton (neori & holm-hansen 1982; li et al. 1984; harrison & platt 1986; tilzer et al. 1986). however, bacterial growth in the antarctic ocean was double of that predicted and had lower q l o than phytoplankton (1.4 versus 2) for the -1 20°c temperature interval (neori & holm-han sen 1982). in this study. q i , , = 1.6 (g12"c) poss ibly reflects a variety of responses in the populations that compound the microplankton. the ets activity measured is a potential res piration rate. and can be converted to actual oxygen consumption ( r ) by applying a factor derived from simultaneous r and e t s activity measurements done on mixed plankton popu lations. some calibrations (packard & williams 1981: williams 1984; packard 1985a; vosjan & nieuwland 1987) yield values of about 3 for the ets/r ratio. however, these studies have been made on temperate microplankton from eutrophic surface waters. although e t s activity and respiration a r e usually well correlated in a given area or plankton community (packard & williams 1981), r / e t s ratio can vary with dif ferent plankton contributions or seasons (see hobbie et al. 1972). r / e t s ratios increase with increased bacterial contribution to overall res piration since bacteria a r e usually more meta bolically active than o t h e r organisms (williams 1984; azam & fuhrman 1984; harrison 1986). also. organisms in cold environments seem to use a larger proportion of their ets for actual respiration (jansky 1963). additional problems relate to the long incubations needed to determine oxygen consumption with the micro-winkler technique (williams & jenkinson 1983): this could promote bacterial growth inside the incu bation bottles, causing an apparent increase in respiration. these a r e reasons why e t s activity results have been directly reported here without conversion t o oxygen consumption. the e t s activities found in this study for the 100 upper m range between 0.5 to 100 mg 0 2 m 3 d ' (mean value 13 mg o2 m-' d-i), which is in the range found for oligotrophic oceanic regions (williams 1984). integrated daily rates for the upper loom were 1 . 7 g o2 m ? d-i and 2 . 7 g o2 m-? d-i for the whole water column. williams (1984) quoted respiration rates in antarctic mic roplankton (0-100 m) ranging from 0 t o 16 mg o 2 m 3 d i , but fts activity in the weddell sea (martinez & estrada 1991) was higher: 0.2 t o 5 3 m g o2 m-3 d i . these values would range between o n e and three-fold those quoted by wil liams, when applying an ets/r ratio of l to 3. vosjan & olanczuk-neyman (1991) reported ets activity of 2-200 mg o 2 m 3 h-' in admiralty bay, antarctica. harrison (1986) found in the high canadian arctic (0-100 m ) a mean value of 60 mg o 2 m-3 d-i and integrated values (100 m) of 4-9g o2 m ? d ' . e t s activity in this study was higher than in the weddell sea and lower than respiration in the canadian arctic. harrison's (1986) results were five-fold higher than in the present study, the main reason prob ably being the higher living biomass in the canadian arctic samples. chlorophyll u in the surface ( m o m ) waters of the canadian arctic ranged from 0.74 to 8 m g r k 3 , whereas at the barents sea stations they ranged from 0.05 to 3.3 mg m3. respiration/chl ratio in the canadian arctic (calculated from data from harrison 1986) biomass and respiratory ets activity of microplankton in the barents sea 199 was 1.7mg o 2 mg ch1-l h-l, and ets/chl in this study was similar, 1.9mg 0 2 mg chl-' h-l. however, assuming that respiration is lower than ets activity, the calculated ratio sets an upper limit for the r/chl a ratio in the barents sea. ets/chl ratios reflect the relative contribution of autothrophs to total microplankton respiration. in phytoplankton-dominated zones, such as upwelling systems, ocean fronts or chlorophyll maximum layers, the ratio is low, and increases away from these zones. the ratio was 0.7 mg o2 mg chl-i h-' at the chlorophyll maximum at station 2, and increased to 2 mg o 2 mg chl-' h-' at the bottom of the euphotic zone at the same station. the range of this ratio was similar in the weddell sea during spring (martinez 1989; martinez & estrada 1991). in the western med iterranean sea the ets/chl ratio ranged from 0.3 mg o2 mg chl-i h-l (chlorophyll maximum and almeria-oran front) and 5 mg 0 2 mg chl-' h-' (oligotrophic central basin) (martinez et al. 1990; martinez unpubl. data). the ets activity, converted t o carbon and day units, had a mean value of 5 mg c m-3 d-', with a range of 0.6-33.6mg c m-3 d-l. the carbon specific rate, or (potential) respiratory carbon turnover, was 0.01-0.07 d-' with a mean value of 0.03 d-', and the integral column value ranged between 0.03 and 0.04 d-l. this means that 3 to 4% of the poc present is potentially consumed each day by respiration. this rate is in the same range as the rate observed in sediment trap material in the same region during the same cruise, between 40 and 300 m depth (wassmann et al. 1991). c/n ratios were similar: 11 in sedi menting versus 12 in suspended matter, indicating similar organic matter. this is in agreement with the characteristics of recycled production in sum mer in the region (wassmann 1989; wassmann et al. 1991). respiratory turnover rate of carbon in barents sea microplankton in summer was a fifth of the rates found in the weddell sea in spring: 0.02 to 0.05d-' with a mean of 0.17d-i (martinez & estrada 1991), in spite of lower temperatures (-1.7 to 2°c). the reasons probably are the high living/dead organic matter ratio and high bac terial contribution in the weddell sea (boldrin pers. comm.; delille 1989), with c/n ratios of 6.5, close to c/n = 5.7 reported for marine bac teria (mann 1982). vosjan & nieuwland (1987) found rates of 0.12 d-' in antarctic waters, and 0.3 d-' in the north atlantic during the spring bloom, and much higher values, averaging 0.9 d-i, in tropical waters at temperatures between 10 and 27°c. high detrital/living ratios together with low temperatures account for the low carbon-specific enzyme activity found i n the barents sea during summer. respiratory ets activity of microplankton can be compared with existing data on primary pro duction by phytoplankton in the barents sea by rey et al. 1987. their estimation of annual pro duction was 69 g c m-2, taking place only during six months. we can assume that the ets activities measured in this study are maintained during the same six months (a low estimation), and that respiration in the colder months is negligible. on basis of data from the more pelagic stations 1 and 2, the carbon potentially respired would average 140 g c m-2 for the six-month period. using the r/ets = 0.3 ratio, this would correspond to 47 g c m-2. assuming that the numbers given by rey et al. estimate net production of the micro plankton community, then gross production, by adding microplankton respiration, would be between 116 (taking r = 0.3 ets) and 209 g c m-2 (taking r = ets). this means a respiration of between 40% and 70% of gross primary pro duction. although this is a rough estimate, it provides an approach to estimate the range and order of magnitude of the production-respiration relationship in microplankton in the barents sea. these results show that most of the respiratory activity of microplankton in the barents sea occurred in the upper layers (<60m) and was correlated with phytoplankton biomass. ranges of respiratory ets activity, as well as column integrated values, were higher than those reported from the antarctic (williams 1984; mar tinez & estrada 1991) and lower than respiration in other arctic regions (harrison 1986). it has been postulated that arctic microplankton res piration may be substantially higher than that in the antarctic. the results of this study do not support this hypothesis. my results rather provide evidence of the similarity of function between microplankton communities of arctic and tem perate oceanic areas. acknowkdgernenrs. i am indebted to e. sakshaug for the opportunity to participate in a pro mare cruise. h . r. skjoldal, as the cruise leader, provided logistic support and cooperation. and allowed me to use the chlorophyll and nutrient data measured on board. the help provided by the staff at the institute of marine research in bergen is appreciated. thanks are extended to the department of microbiology, university of bergen, for allowing me to use their chn-analyzer. comments 200 rosn martinez and suggestion5 o f e srikshdiig. t t. pdckard a n d 1 5 5 0 anon! rnous r e \ i c u c r \ are appreci.itcd. finiincial support 5\25 pro! ided by the pro marc progr;imnic ( n o r i r a y ) a n d g r a n t paq.8faxii i from the spani9h cic'yt references ardm. f. & fuhrman. j . a . iyhj: measurement of hac terioplankton growth in thc w a and its regulation h! e n \ i r o n mental conditions. pp. 1 7 s i 9 6 in hohhic. j . e . 8: williams. p j . ie b: hererorruphic ciclit~in i i i the yea plenum. s . y chabot, b. f . 1979: metabolic and enzymatic adaptations to low temperature pp. zx.l-301 in underwood. l. s . et ai. (cds. ): coniparariiv m e c h o r i u i n s of cold adaprurioti. aca demic press. usa delille. d . . brandini. f.. ihi. k . . kuosa. t i . . norrman. b. 1989: microbial communitieh ber. 2 . p o l a r f o r z . 62. 1 1 3 1 16. harrison. w . p . 1986: respiration and its size-dependence in microplankton populations from surface waters of the canadian arctic. polar biol. 6. 14s1.52. harrison. w . g . 8: platt. t i986 phi)tosynthesis-irradiance relationships in polar and temperate phytoplankton popu lations. polar b i d . 5 . i5.f.lhl. hobhic. j . e . holm-hansen. 0.. packard. t . t . pomero!. l . r . shcldon. r . w . thomas. g p 8: wiebe. w . j . 1977. a study of the distribution and acti\rity of microorganisms in ocean water. limnol oceonogr. 17. 544-555. ticxhachka. p. w . & somcro. g . n 1971: biochemical adap tation to the en\ironment p p . ys-i65 in h o a r . w . s & randall. d. j . ( c d s i : fish p h u i o l o g ! . vol 6 . academic press. hochachka. p w 8: somero. g . n. 1973. srraregies of bio chemical adaplariori saundcrs. philadelphia. 3 5 8 p p jansky. l. 1963: body organ cytochrome oxidase activity in colda n d warm-acclimated ralr. can. j . biochern. phwol. 41. 1847-1851. kenncr. r. a . & ahmed. s j 1975: mcasurcment of elcctron transport activities in marine phytoplankton mar. b i d 33. 11'+128. li. w . k. w . . smith. j . c & platt. t . 1984: temperature response of photosynthetic capacity and carboxylase actisit) i n arctic marine phqtopfankton. .mar. €ro/. f r o g . ser. 17. 237-243. mann. k . h . 1982ecology of coasrol waters. a sysiems approach. blackwell. 3 2 2 pp. martinez. r . 1980: t h e activity of the respirator). electron transport syztcm in microplankton. e r r . 2 p o l a r f o r s . 6 2 . 13bl41 martinez. r. & estrada. m 1991: respirator! e t s activit! of microplankton in the weddell sea during spring: influence of the icc coverage. polar b i o / . i n press martinez. r . . a r n o n e . r . a . 8: velasquez. z 1990: chloro phyll a and respirator) actisity in microplankton from surface haters of the western mediterranean sea j . g e o p h i s . res. y i c ' 2 . l h l f 1 6 ? ? ueori. .a 8: holm-hanscn. 0 1982: effect of temperature on rdtc of photos)nthcsis in antarctic ph!toplankton. polar b i d . i 3.1-38. packard. t t. 1y71 t h e measurement of electron transport a c t i \ i t y i n marine p h > t o p l a n k t o n . j . ,mar res. 29. 235-241. packard. t t . 1979 respiration and respirator! electron trans port acti\it\ in plankton from thc northwest african upucll inp area 1 .&fur r r i 37. 71 1-73: pdchdrd. t t. iyxsa: measurement o l electron transport acti\it! ot microplankton. .-ldi.. aqitur. microhiol. 3 . 707 ih i pjckjrd. t t . i y x 5 h : ox!gen consumption i n thc ocean: meas uring and mapping with enzyme analysis. p p 177-21)y in zirino. a . ( c d ) : mopping srraregies it1 c~hernical o c e a r i o x r q h y . american chcmical society. washington. d.c. packard.t t. & williams. p. j . ic b. 1981: ratesofrespiratory ox!gen consumption and electron tranzport in surface sea u a t c r from the northwest atlantic. oreutrol. acru 4. 351 3 5 x pdckard. t . t . . d e \ o l . a . h 8: king. f d . 1y75: t h e effect of temperature on the respiratory electron transport system in marine plankton. d e e p s e a res. 22. 237-249. re!. f & loeng. h . 19x5: t h e influence of ice and hydro graphic conditions on the development of phytoplankton in the barents sea. pp. 4%63 in gray. j . & christiansen. m . e . ( e d s . ) : ,\furine hiolog?. ofpolor regiort.5 arid rhe effecrs of s r r d s ori tnmirie or#oni.vns. j , wilcy and sons. re!.. f . skjoldal. f i . r . & slagstad. d 1987: primary pro duction in relation t o climatic changes in the barents sea. p p 29-46 in locng. h ( e d . ) : the effecr of oceatiogruphic coridirions on dirrriburiori arid poprtlariori dynamics of com mercrulfish stocks i t t rhe barents sen. proc. soviet-norwegian s > m p . . murmansk. 26-28 may 1986. shaffer. g . 1987: redfield ratios. primary production a n d organic carbon hurial in the baltic sea. d e e p s e a res. 3 4 . 76f784. simpkins. i . 1986. general principles of hiochcmical invcs tigations. p p . 1-42 in wilson. k . & goulding. h . ( e d s . ) : principles arid techniques of practical biochemirrry. arnold press. london somero. g 1969: pyrusate kinase variants of the alaskan king crab. biochern. j . l l 4 . 737-241. tilrer. m . m . , elbrachler. m . . gicskcs. w . w. & bccse. b 1986: light-temperature interactions in the control of photosynthesis in antarctic phytoplankton. polar. b i d . 5 . 1 0 1 i i i . vosjan. j . h & nieuwland. g . 1987: microbial biomass and respirator! activity in the surface waters of the east banda sea and northwest arafura sea at the time of southwest monsoon. littirial. oceaiiogr. 32, 767-775. vosjan. j . h . & olanczuk-neyman. k . m . 1991: influence of temperature o n respiratory e t s activity of micro-organisms from admiralty bay. antarctica. nerh. 1. sea res. 28. 221 2 2 5 . wassmann. p. 1989: sedimentation of organic matter and sili cate from the cuphotic zone of the barents sea. r a p p . p-u reun. cons. inr. explor. m e r 188. 108-1 1 1 . wassmann. p.. martinez. r . & vernct. m . 1991: kcspiration and biochemical composition of sedimenting organic matter during w m m e r in the barents sea. cotir. s h e l f r e s . i n press. williams. p. j . le b . 19x1: microbial contribution t o overall marine plankton metabolism: direct measurements of res piration. oceanol. a c i a 4 . 359-364. williams. p j . le 8. 1981: a review of measurements of re\ piration rates. p p . 357-390 in hobbie. j . e . & williams. p j . le b . ( e d s . ) . hererorrophic aciioirv iri rhe sea. n a t o conference series. i v . 15 plenum press. new y o r k . williams. p. 1. le b . & jenkinson. n . w . 1983: a transportable microprocessor-controlled precise winkler titration suitable for field station and shipboard use. limriol. oceoriogr. 27. 576-581. research note some notes on glacial geomorphology in the inner part of st. jonsfjorden, svalbard arnt-ivar kverndal kverndal. a . 4 . 1991: some notes on glacial geomorphology in the inner part of st. jonsfjorden. svalhard. polar research 9(2). 215-217. working as a field assistant for dr. harmon maher during the norwegian polar research institute's svalbard expedition 1991, a:i. kverndal had the opportunity to do a large-scale study on thc glacial geology in the st. jonsfjorden area. this note emphasises thc glacial geomorphology connected to the konowbreen/osbornebreen glacier system: i t also comments on thc possibilities for further research in this area. arnl-ivar kverndal, university of t r o m m . departtnenl of geology. tromsm mu.reum. n-9000 trojnsm. norway. st. jonsfjorden (78"30'n, 12"30'e) is situated on the western coast of spitsbergen, svalbard (fig. 1 ) . the area is characterised by jagged peaks, nunataks, and the many glaciers draining down to thc fjord. the bedrock geology is dominated by a complex composition of metamorphic rocks, the oldest of which comprise the hecla hoek hasement rocks that were deformed and met amorphised during the caledonian and older events. overlying the hecla koek we find the upper paleozoic and mesozoic rocks, deformed and metamorphised during the early tertiary opening of the norwegian-greenland and arctic oceanic basins (maher 1989). the glaciers in the st. jonsfjorden area are of the typical spitsbergen typc: topographically influenced ice-masses drain ing down to the fjord from composite accumulation areas. supraglacial meltwater drainage, the observation of icings, and the significance of icc-cored moraincs in the frontal areas indicate a subpolar tcmperature regime of the st. jonsfjordcn glaciers. a recorded surge on osbornehreen and the estimation that yo%, of the glaciers on svalhard are of the surging typc (hagen & liestdl 1990) suggest that most of the glaciers around st. jonsfjordcn are influenced by this special periodic hehav iour. the phenomenon makes it difficult to establish a relation ship between climatic and glacier front variations in the region. glacial geology according to liestd (1988). the advance of the glacier fronts o n western spitsbcrgen in the second half of the last century represents the maximum extension of ice cover in the holocene. maps, aerial photographs, and mass-balance investigations in the kongsfjorden area show that the glaciers' icc-mass volume change has been negative since the beginning of this century (hagen & liest01 1990; lefauconnier & hagen 1990). this continuous deficit in mass-balance can be explained by higher summer temperatures (hagen & liestol iy90), or by the low precipitation rate (liest01 1988). in the inner part of st. jonsfjorden, the two glaciers konow breen and osbornebrecn compose the most dominant glacier system in the area (fig. 1). distally to today's glacier fronts, lateral moraines along both sides of the fjord give an indication of the system's extensions during the holocene. even though the moraines have a very complex morphology, it is possible t o interprete different glacial stages. the marginal and oldest moraine, possibly deposited in the second half of the last ccntury, gives a picture of the system's maximum holocenc extension (fig. 1). the moraines indicate a low-gradient ice profile, extending to the piriepynten and konowfjcllet area. where push-moraines containing marine scdiments and shcll fragments were discovered (fig. 2). the ridges are locatcd 2 7 m a.s.1.. and both the situation and morphology connect them to thc konowbreen/osbornebreen glacier system. the marine sediments and the content of shells indicate that the glacier front was grounded during this advance. glacial erraties arc found in the same area as thc push moraines (fig. 1). in fact, at konowfjellet erratics are found on top of the ridges. they are conglomerates of carbonifcrous age and limestones of permian age. belonging respectively to the tornkanten and kapp starostin formations. the latter formation is only to be found in the osbornebreen drainage area. documenting the origin of the morainic material. between 1987 and 1089 osbornehreen surged, and the glacier front advanced about 2 km (fig. 1). a 40 to 5 0 m lowering of the ice-profile in the accumulation area shows how ice-mass surplus has been transported from this area down t o the frontal part of the glacier. today the front displays a typical post-surge situation: a heavily crevassed frontal area. steep lateral sides. and a high calving rate. the present glacier flow is not sufficient some notes on glacial geomorphology of st. jonsfjorden, sualbard 217 fig. 2. push-moraine at piriepynten. dr. maher as scale. fig. 3. vertical section at the front of osbornebrecn docu menting that the glacier has been sliding over the old ice-cored moraine, leaving it almost undisturbed. further research the complex geology and geomorphology. the different typcs o f glaciers draining down to t h e fjord. and the fact that 01 borncbreen surged between 1987 and 1989 all make the st. jonsfjordcn area very interesting for further and more detailed research. however. thcrc have been few investigations in the st. jonsfjorden arca, probably because of its inaccessibility. only one paper published by forman (1989) is known to the author. one of thc most challenging topics in glacial geological rerearch today is achicving better understanding of thc geo morphological proccsscs associated with glacier front oscil lations. in st. jonsfjordcn the glaciers are easily accessible by boat. making i t possible to investigatc many different types of glaciers. thc osborncbrcen surge also makes it possible to carry out detailed studics on the formation of marginal moraines in front of a surging glacier. bccausc of thc complex geology in the st. jonsfjorden area, a detailed petrographical mapping of morainic material and glacial erratics can provide valuable information about glacier limits. a 1 : 100000 scale bedrock map is in preparation at the norwegian polar research institute. references forman. s. l. 1989: late weichselian glaciation and dcglacia tion of forlandsundct area. western spitsbcrgcn. boreus 18, 51-6u. hagen, j. 0. & liestd, 0. 1990: long-term glacier mass balance investigations i n svalbard 1950--1988. a n n . glaciol. 14, 148-152. lefauconnier, b. & hagen. j . 0. 1990: glaciers and climate in svalbard, statistical analysis of the brbgger glacier mass balance for the last 77 years. ann. glaciol. 14, 102-106. liestol, 0. 1988: the glaciers in the kongsfjorden arca, sval hard. n o r . geogr. t i d s k r . 4 2 , 231-238. maher, h . d . , jr. 1989: photointerpretation of tertiary struc tures in platform cover strata of interior oscar i i land, spitsbergen. poiur kesearch 6, 155-172 research note additional evidence of pre-silurian high-pressure metamorphic rocks in spitsbergen yoshihide o h t a , yoshikuni hirol and t a k a 0 hirajima ohta, y., hiroi, y. & hirajima. t. 1983: additional evidence of prc-silurian high-pressure metamorphic rocks in spitsbcrgcn. polar research i n.s., 215-218. it has been previously suggested that the high-pressure metamorphic rock complcx of motalafjclla. central-western spitsbergen, is older than lower silurian. an unconformity has been discovered at the base of a limestone which contains fossils similar to those reported as lower silurian from the same massif. this proves that the high-pressure metamorphics represent an older rock complex. the unconformity surfacc is invcrted in the area, and large recumbent folds involving the silurian bulltindcn formation havc been mapped. these folds are considered to be prc-carboniferous, k'oshiliide ohra. norsk polarinsriturt. rolfrraangueieri 12, 1330 oslo ltcfthaun. norway; yoshikririi hirrri. inrtrriire of eurrh scierice, faculty of education, kunuzawo unic~ersify. kanuzuwa, y20 j u p u t i , t u k u o hirulima. deparrrnent of geology arid mineralogy, fucirlry of science, kyoru uniwrsir)., kyoro. 606 j a p a n : a u g u r i983 (revised ocroher 1983). ' d ~ . p ~ l a r l ~ s ~ " unit of mainly grcen and black phyllites with subordinate amounts of mcta-basic rocks (partly showing pillow structure j . a blueschist-eclogite complex has been reported from motaquartzite, dolomitic rocks and serpcntinitc. and an uppcr unit lafjclla, central-western spitsbcrgcn (horsficld 1972: ohta of mainly high-pressure metamorphic rocks and schistose lime 1978: manby 197s: ohta 1979). k/ar ages have been obtained stone with a small amount of chert. the phyllitcs of the lower from the rocks in the range 102-475ma and at 621ma (horsfield unit and the micaccous schists of thc uppcr unit have very 1972). a flyshoid succcasion, the bulltinden formation (horsstrong diaphtoritic cleavages. field 1972; hjelle et al. 1979: harland et al. 1979). is clotely conncctcd with the complex. and fossils from thc formation are introduction considcrzd to be lower silurian in age (scrutton ct al. 1976) some pebblec crt altcrcd schists similar to the slaucophane description of the unconformity schists wcrc found in boulder conglomerates of the bulltinden formation. and a pre-silurian age for the high-pressure meta morphic rocks has been suggested (horsficld 1972). during thc 1983 field survcy a n unconformity was discovered at the base of the limestone member of the bulltinden for mation. and this protides concrete evidence that the high-pres sure metamorphism is prc-silurian. in this paper field obscr vations of thc unconformity arc described and a preliminary re-interpretation of the geological structure of the area is prexnted. geological outlirie of motalafjella (fig. 1) the bulltinden formation make\ up roughly 213 of the north eastern motalafjclla. and consists mainly of boulder conglom crate. black shale. grey \aiid\tone alternations. and limcstonc. thc remainder of the massif includes phyllitic rocks and the high-prcrsurc metamorphic rocks of the vestgotabreen for mation. all planar structures, both bedding and schistosity. show a monoclinical structure with a gentle curve of strihes. the mean dip is moderate to the west and southwest. a 1cl20 m thick limestonc member of the bulltinden for mation crosse\ the massif from nw to se. the boulder con glomerate changes greatly in thickness, and the shale contains several limcstonc icnses. most of which are fossilifcrous. the vestgotahrcen formation consists of two units: a lower the unconformity has been obscrved clearly at two localitics ( a and b in fig. 1 ) and supporting evidence has been found at several other localitics (c-g i n fig. i ) . locality a. (fig. 2 ) an about 20 m thick, dark grcy limestone bed of the bulltinden formation forms a vertical cliff here and i s overlain by a dolom itic layer with a characteristic brown, weathered colour. the lower surfacc of the dolomitic layer has a strongly weathered appearance and is brecciatcd into angular-subangular blocks, the interstices of which arc filled with conglomcratic grcy limestone. the limestone is conglomeratic for 2-5 m from its structural upper surface. the clast population includes subangular-rounded hlocks and pebbles. up to 20 ciii. of mninl! dolomitic rocks and subordinate numbers of quartzitc. grcen phyllite, schistose limestone and scrpcntinite. all components derived from the vestgotabreen formation. the matrix is dense, grey limestone and contains gastropods similar to thobe reported by scrutton et al. (1976). fossil-bcaring limestone pebbles are often found in the boulder conglomerate structurally underlying the limestone. a large recumbent syncline crest can be clearly seen on the eastern cliff in thc conglomerate. thcsc observations imply that the limestone has an uncomformity at its stratigraphic base, although the whole succession is now overturned. 716 yoshihide olira et 01. locrilir~~ b t h c llmt<iit 1~etnsc.n the limemint. and t h s dolomitic r o c k i \ e \ p t w d dizcontiniiowl! . the contact u r l a c c dips i(l2ll~ to t h e u s \ t i he l i r n c s t o n c 15 conpiomeratic lor 2-3 m from thc contact a n d h a r whangul,ir t o uell rounded blocks and pehhlc\ of doiciinitic rock5 n hich ztrusturall! 0 1 crlie t h e limestons g.iv t h e gre! hniestonc undcrlies a mcta-basic rock of the t i o p i d \ h d \ e h c c n t o u n d u i t h i n t h e conglomeratic rocks i n the \'cctgotahreen forination a t locdit! c t h e limestone contains northcrn pdrt and zomc cross-laminatsd beds arc totall! cornzoine \and! and conglomeratic layers iicar the contact. and t h e posed of fragment> of gastropods. cephalopods. and rrilohltea c o n t a c t surface does ncrt show a n y trace of slip. t h e precise in t h c wuthe:ri part. thin lilnis of grc! l i i n e s t o n e penetrstc a l o n g l o i n r plaiie\ u t the dolamitic tock. other localities high-pressure metamorphic rocks 217 fig. 2 . sketches of the unconformit) at locality a (after photographs). a : gp-green phyllite. d-massive dolomitic ruck, b brecciated and brown-weathered dolomitic rock, c conglomeratic grey limestone, l grey limestone, w -white lime stone. cgbouldcr conglomerate. b: contact between the brecciated dolomitic rock and the conglomeratic limcstone. 5 sandy limestone. c fossils occurring in the brecciated dolomitic rock. f-gastropods. d -dolomitic rock block. contact is not exposed at locality d . but many scree blocks of g r q limestone contain subangular blocks and rounded pebbles of quartzite, green phyllite and dolomitic rock on the ridge south of skipperbreen (locality e ) . the grey limcstone underlies an epidote-actinolite greenstone of the ve\tgotabrcen formation without any slip plane. thin layers of green and white limestone, each laver less than locm thlck. form a banded structure near the contact for less than 5 m. a stock-like epidote-actinolite greenstone is enclosed by the grey limestonc o n the northern ridge of skippcrbrsen (locality f). the limestone overlies the greenstones and high-pressure meta morphic rocks in the central and western part, showing banded structure as in locality e , while a fault cuts the eastern part and the limestone is in contact with a dolomitic rock without signs of mobement. thus, an overturned anticline is exposed here. although being cut by the fault. t h e grey limestone underlies a brown dolomitic layer and greenstones o n the southrrn slopc of bulltinden (locality g ) . without slip. the <onglomerate layers structurally below the limestone show overturned cross-bedding and grading summary all observations described above. despite the complexity of the folding. prove that the grey limestone member of the bulltinden formation formerly rested unconformably on various rocks of the vestgotabreen formation. this is direct evidence that the high-pressure metamorphic rocks of the vestgotabreen for mation are older than the silurian bulltinden formation. large recumbent folds involving the bulltinden formation are obvious. the hecla hock rocks contain nearly isoclinical folds with sub-vertical axial planes, and are unconformably covered by lo\ver carboniferous sandstone on both northern and southern sides of eidembukta. about 5 kni west and south west of the present area. isoclinical folds with similar stylc and axial direction occur in the carboniferous rocks along the east e r n margin of the tertiary graben of forlandsudet. 5 k m north west of the present area. but they have different dimensions from the above mentioned ones. accordingly. these large recumbent fold, developed i n the hecla hoek rocks are most likely older than carboniferous. acknowledgrmetit. -this is the first report from the co-oper ation project between norsk polarinstitutt and kyoto univer sity, japan (represented by prof. shohei banno). the japanese participants were financed by the polar research committee of kyoikusha co. ltd.. tokyo. references harland, w . b.. horsfield. w . t . . manhy, g. m . & morris a . p. 1979: an outline prc-carboniferous stratigraphy of central western spitsbergen nor. polarinst. skr. n o . 167. 11!9-144. hjelle. a , , ohta, y . 8; winsnes t. s. 1979: hecla hoek rocks of oscar i1 land and prins karls forland. svalbard. nor. polarinst. s k r . no. 167. 145-169. horsfield, w . t. 1972: glaucophane schists of caledonian age from spitsbergen. geol. m a g . l o y ( 1 ) . 29-36. manby. g . m . 1978: aspect of caledonian metamorphism in central western svalbard with particular reference t o the 218 yoshihide ohta et al. glaucophane schids of oscar 11 land. polnrforsrliuri~ 48 (l,.?l. 92-10?, ohta. y . 1978: caledonian metamorphism in svalbard. with some remarks on the basement. polnrforschung 48 t l , ' 2 ) . ohta. y . 1979: blue schists from motalfjella. western spits bergen. a'or. polunrirr. s k r . no. 167. 171-217. scrutton. c. t.. horsficld. w . t. & harland. w . b . 1976: silurlan fossils from western spitsbergen. geol. m u g . 103 78-9 1 . ( 6 ) . 519-523. two major unconformities beneath the neoproterozoic murchisonfjorden supergroup in the caledonides of central nordaustlandet , svalbard david g . gee and alexander m. teben’kov gee d. g. & teben’kov a . m . 1996: two major unconformities beneath the neoproterozoic murchisonfjorden supergroup i n the caledonides of central nordaustlandet, svalbard. polar research l s ( i ) , x1-91. two unconformities have been found in central nordaustlandct. new mapping has located a major unconformity at the base of the neoproteroaoic murchisonfjorden supergroup, with quartzites and basal conglomerates of the djevleflota formation unconformably overlying dark phyllites o f the helvetestlya formation and metavolcanic rocks of the svartrabbane formation. a second unconformity separates the helvetesflya from the svartrabbane formations. these rocks were isoclinally folded, metamorphosed in lower greenschist facies, and, apparently, syntectonically intruded by grenville-age granites, prior to uplift, erosion and neoproterozoic deposition. caledonian tectonothcrmal activity, as recorded i n rhe neoproterozoic srrara, appears t o vary very little across svalbard’s eastern terrane from ny friesland, in the west, to murchisonfjorden in western nordaustlandet and, via wahlenbergfjorden, to the central nordaustlandet area, described here. upright folds with associated high angle, usually e-dipping cleavages. charactcrise the caledonian deformation over an east-west distance of about 100 km. this evidence allows the possibility that the pre-devonian basement, to the east of nordaustlandet, beneath the northern barents sea (barentsia), may be composed of grenville-age complexes little influenecd by caledonian tectonothermal activity. alternatively, barentsia is dominated by caledonian hinterland tectonics, with extensive middle paleozoic tectonothermal reworking of a precambrian basement. david g . gee, department of geophysics, uppsala university, villauagen 1 6 , s-752 36 uppsala, sweden; alexander m . teben’kou, polar marine geological expedition, ul. pobedy 24,189 510 lomonosoo, russia. introduction some of the most inaccessible, exposed areas of the barents shelf occur in northeastern svalbard, where crystalline complexes of granites, augen gneisses and migmatites have long been known (nordenskiold 1864, 1866) to be overlain by nearly unmetamorphosed sedimentary rocks (the hecla hoek formations) of neoproterozoic and early paleozoic age (kulling 1932, 1934). the relationships between these crystalline rocks and the fossiliferous successions have been much dis puted, and only recently (gee et al. 1995) has clear evidence been presented of a grenville age for some of the granites. the latter intrude both the migmatites and some of the metasedimentary rocks (fig. 1). in northwestern parts of nordaustlandet, an unconformity, first documented by ohta (1982a), separates low grade metasedimentary rocks (the brennevinsfjorden group) intruded by ca. 950 ma granites (gee et al. 1995), from an overlying volcanic and volcaniclastic sequence (the kapp hansteen group); the latter underlies well-docu mented neoproterozoic sandstones, shales and carbonates of the murchisonfjorden supergroup (kulling 1934; flood et al. 1969; ohta 1982a, b). a significant unconformity is inferred to also exist at the base of the murchisonfjorden supergroup, but the contact, occurring beneath lady franklin fjorden, is apparently not exposed on land in western areas. further east, in central nordaustlandet, a similar unconformity (or unconformities) has been inferred by various authors, but not pre viously demonstrated. thus, sandford (1950, 1956), on the basis of several expeditions to the area, concluded that a major unconforrnity should exist between underlying metamorphic complexes and overlying little-metamorphosed sedimentary and volcanic rocks; however, neither he nor flood et al. (1969) were able to unambiguously demon strate a regionally significant unconformity. this paper documents two major breaks in the stra tigraphy; we now know that the problems of their identification relate to the existence of low grade metasedimentary rocks of both mesoproterozoic and neoproterozoic age. 82 d. g . gee & a . m. teben’kou fig. i . geological map of nordaustlandet and n y friesland (from gee et al. 1995), with location of fig. 2 . previous work in central nordaustlandet the caledonian bedrock of central nordaust landet is exposed between two major ice-caps, vestfonna and austfonna, in the vicinity of rijpfjorden and inner wahlenbergfjorden and in the broad open n-trending valley connecting these two waterways. south of wahlenberg fjorden, flat-lying carboniferous successions unconformably overlie the caledonian rocks. geological maps of the area have been published by sandford (1956), flood et al. (1969), hjelle (1978), ohta (1982~) and lauritzen and ohta (1984), and several russian expeditions have pro vided unpublished reports of the pre-carbon iferous geology. the regional structural relationships in central nordaustlandet were established by sandford (1956). h e showed the approximate distribution of the rock units, with migmatites and granites (his “metamorphic complex”) occurring in a major n-trending antiform extending through rijpdalen, from innermost wahlenbergfjorden to two major unconformities beneath the neoproterozoic murchisonfjorden supergroup 83 rijpfjorden, and flanked to the east and west by synforms containing neoproterozoic successions. the rijpdalen antiform plunges north in the south and south in the north, and, from the latter area, the migmatites and granites spread north eastwards to occupy most of northeastern nor daustlandet . sandford (1956) recognised several of the neo proterozoic formations that had been defined further west by kulling (1934) in the classical murchisonfjorden area. kulling (1934) had shown that the various pre-vendian units in that area dolomites, limestones, shales and sandstones (his murchison bay formation) were underlain, on botniahalvoya, by a succession of volcanic and low grade sedimentary rocks that he referred to as the cape hansteen formation. in central nordaustlandet, similar lithologies, though with only subordinate volcanites, were found by sand ford t o separate the sandstone units (flora series) of the murchison bay formation from the under lying “metamorphic complex”. pink granites were recorded t o cut both the cape hansteen for mation and the underlying rocks. sandford com mented (1956, p. 358), “it is pertinent, then, to consider whether the cape hansteen formation is stratigraphically unconformable on the meta morphic complex, o r is a part of a disharmonic mass between the surface of the complex and the competent beds of the flora series.” he noted (1956, p. 357) the presence of “sheets of meta morphosed sediments” between the granitic rocks of the “metamorphic complex”, but no evidence of metamorphic transition into the low grade cape hansteen rocks; he therefore concluded that an unconformity must exist between them. the structural complexity of the migmatites and the granites, contrasting with the relatively simple more or less cylindrical folding of the neo proterozoic strata, also prompted this inter pretation. flood et al. (1969) carried out an extensive helicopter-supported mapping program of nord austlandet in 1965. in central nordaustlandet, they recognised that there was a metamorphic transition from the underlying migmatites and foliated augen granites into the so-called cape hansteen formation, with staurolite, andalusite and garnet crystallising syntectonically in the immediate contact zone. metamorphic grade decreases rapidly to lower greenschist facies away from the contact. younger reddish granites cut all these rock units. flood et al. (1969) showed that the low grade metamorphosed sedimentary and volcanic rocks had a more complex structural history than the overlying murchisonfjorden lithologies and they therefore preferred the hypothesis (flood et al. 1969 pp. 95-96) that a major unconformity separated these two strati graphic units. nevertheless, the exact location and interpretation of the importance of the uncon formity were disputed, being influenced not only by the field relationships, but also by the first isotope age-determination studiesrb/sr whole rock and mineral ages of ca. 600 ma ages on schists of the “metamorphic complex” (hamilton & sandford 1964). support for the interpretation that the murchisonfjorden neoproterozoic strata were underlain by a basement complex of mig matites, granites and low grade volcano-sedi mentary rocks was found locally, for example, east of bengtssonbukta, where a quartzite con glomerate was recognised (winsnes in flood et al. 1969, p. 37) to discordantly overlie low grade metasediments. in general, the lithologies below the mur chisonfjorden supergroup in central and western nordaustlandet are similar. however, whereas in western nordaustlandet flood et al. (1969) recognised that the sub-murchisonfjorden rocks composed two major mappable units, the bren nevinsfjorden and kapp hansteen formations (together comprising their botniahalvoya group), in central nordaustlandet they were unable to distinguish these formations. and in the latter area, an independent quartzite and dark phyllite unit, with subordinate intercalations of carbonates, was identified the austfonna for mation, overlying the other formations of the botniahalvoya group in the rijpdalen antiform. subsequent work on botniahalvoya (gee et al. 1995) has demonstrated that the brennevinsfjor den and kapp hansteen units are both sub divisible into formations and therefore should have group status. because a major unconformity separates these units on botniahalvoya (ohta 1982c), the term botniahalvoya group was aban doned (gee et al. 1995). the stratigraphy of the murchisonfjorden supergroup (table 1) has also been modified since its early definition by kulling in 1934 (the murchison bay formation) and correlation from the type areas, eastwards into central nord austlandet is not without problems. in the murchisonfjorden area, below v e d i a n tillites, kulling (1934) distinguished six series (for t ab le i . st ra ti gr ap hi c co rr el at io n of t h e m es o a nd n eo pr ot er oz oi c su cc es si on s of c en tr al a nd w es te rn n or da us tl an de t w e s t e r n (o th a 19 82 a & b) n o r v ik f m f lo r a f m k a p p l o r d f m c e n t r a l (o ht a 19 82 c) n o r v ik f m f lo r a f m k a p p l o r d f m m e y e r b u k t a f m st ' su bo rd . 1s t) a u s t f o n n a g ro up (i n n v ik h b g d a d je v le f lo t a an d b a s a l q zi te b r e n n e v in s f jo r d e n f or m at io n b r e n n e v in s f jo r d e n f or m at io n n o r d a u s t l a n d e i ce n t r a l (t hi s pa pe r) w e s t e r n i c e n t r a l (f lo od et a l. 19 69 ) w e s t e r n (k ul lin g 19 34 ) n o r v ik s er ie s (s ha le s) c e n t r a l (s an df or d 19 56 n o r v ik s er ie s w e s t e r n (g ee et a l. 19 95 n o r v ik f m n o r v ik f m n o r v ik f m fl o r a f m f lo r a f m f lo r a f m k a p p l o r d f m f lo r a s er ie s f lo r a s er ie s (q ua rt zi te s) s uc ce ss io ns be lo w re pe at ed re cu m be nt fo ld in g. by c a p e h a n s t e e n f or m at io n (p hy lli te s, qz p or ph yr ie s an de si te s ag gl om er at es & co ng lo m er at es ) k a p p l o r d f m (s ha le s) w e s t m a n b u k ta f m (s ha le s) k a p p l o r d f m w e s t m a n b u k t a f m w e s t m a n w e s tm a n . b u k t a f m 1 b u k t a f m w e s t m a n e o k t a f m w e s t m a n b u k t a f m p e r s b e r g e t fr n (q ua rt zi te s) p e r s b e r g e t f rn p e r s b e r g e t f m p e r s b e r g e t f rn f m i m e y e r b u k t a f m ig fe z re _ d ,. ,. .. * . i k a p p h a n s t e e n g ro up 7 0 0 ~ 0 0 ~ b r e n n e v in s f jo r d e n g ro up (i nt ru de d by ca . 9 5 0 m a gr an ite s) d je v le f lo t a f or m at io n w ith ba sa l c on gl om . w ? u n o b r e n n e v in s f jo r d e n (m et as ed .) & k a p p h a n s t e e n (v ol ca ni te ) fo rm at io ns o rm ity ? j v l a u s t f o n n a 8 k a p p p la t e n fo rm at io ns k a p p h a n s t e e n 8 b r e n n e v in s f jo r d e n u nd iff . (m ig m ita te s & gr an ite s in tr ud e b o tn ia h a lv 0y a g ro up ) fo rm at io ns ) h a n s t e e n h a n s t e e n f or m at io n g ro up s v a r t r a b b e n e f or m at io n 2 0 0 0 0 0 ~ w h e lv e t e s f ly a f or m at io n (i nt ru de d by ca . 1 0 5 0 m a gr an ite s) c a p e h a n s t e e n f or m at io n m et am or ph ic co m pl ex (m ig m at ite s & gr an ite s) two major unconformities beneath the neoproterozoic murchisonfjorden supergroup 85 mations) grouped into two main units, and inter preted the lower part of the succession to be repeated by recumbent folding. flood et al. (1969) placed the upper units (dominated by dolomites and limestones) into the roaldtoppen group and the lower (shales and quartzites) into the celsiusberget group. they rejected kulling’s (1934) “recumbent fold” interpretation and recognised beneath the celsiusberget group a third cycle of shales and quartzites, the frank linsundet group. subsequently, ohta (198213) showed that the lowermost quartzites of the franklinsundet group (the persberget formation) were underlain by another, somewhat different shale-dominated unit, which he named the meyerbukta formation. in central nordaustlandet, the general murchisonfjorden supergroup relationships were established by the mid 1950s (e.g. sandford 1956), with the vendian tillites exposed on the northern side of inner wahlenbergfjorden, underlain by the carbonates of the roaldtoppen group and shales and quartzites of the celsiusberget group. flood et al. (1969) recognised the formations of the franklinsundet group, northeast of vestfonna (north and south of bengtssonbukta) and further south in inner wahlenbergfjorden (north of etonbreen). the basal quartzites of the franklinsundet group were correlated with the persberget quartzites and shown to directly over lie the austfonna formation along the eastern margin of vestfonna. further east, quartzites and overlying shales in the venesjcben synform were shown to be similar to the persberget and westmanbukta formations. however, in these eastern areas, they rest on the undifferentiated volcano-sedimentary rocks of the “botniahalv~y a group” and unconformable relationships were therefore inferred. ohta’s (1982~) map of central nordaustlandet revised the stratigraphic relationships between the murchisonfjorden supergroup and underlying rocks. h e interpreted the austfonna formation lithologies t o be equivalent t o his newly defined meyerbukta formation (from western nordaustlandet) of the basal murchisonfjorden succession. he upgraded the austfonna unit to group status and included within it three for mations, a basal quartzite, a middle shale dominated section (the djevleflota formation) and an upper sandstone-shale unit (the innvik hagda formation). h e also documented the local “basal quartzite” (ohta 1982c, p. 5 2 ) , enter taining the possibility of a regional break beneath the murchisonfjorden supergroup. however, both granite intrusions and migmatisation were thought to influence the austfonna group, and these were regarded therefore as caledonian. new mapping of central nordaustlandet in 1994, a camp was established on helvetesflya, in the watershed between rijpdalen and flaum dalen. this allowed a ten day investigation of the central part of the area between vestfonna and austfonna and a closer examination of the relationships between the murchisonfjorden supergroup strata and underlying volcano-sedi mentary rocks. the new mapping (fig. 2 ) extended from the murchisonfjorden basal contact along the margin of vestfonna in the western limb of the rijpdalen antiform, eastwards via the venesjcben synform to the kvartsitthaugen synform, exposed along the edge of austfonna. the type area for the austfonna group was not within the range of the 1994 operations, but was examined briefly in 1995. similar major caledonian folds, further west along wahlenbergfjorden, involve vendian til lites and, in the vicinity of hinlopenstretet, cam bro-ordovician strata; in central nordaustlandet, these are upright structures, with a cleavage in the shales dipping generally at high angles east wards. a variety of faults complicate the fold geometry of the major n-trending rijpdalen antiform and flanking synforms. described below are the lithologies and struc tures of the helvetesflya area, with a focus on the evidence for major unconformities beneath the murchisonfjorden supergroup strata and within the underlying volcano-sedimentary succession. lithologies and stratigraphy the stratigraphy of central nordaustlandet is treated here in two parts: underlying units, equivalent to flood et al’s (1969) botniahalvcbya group (referred to here as the helvetesflya and svartrabbane formations), and unconformably overlying units in the basal part of the murchisonfjorden supergroup. with regard to the latter. one of the formations included bv ohta i development of an unconformity beneath his fir 2 geological map of the area between vestfonna and austfonna. central nordaustlandet. (1982~) in the austfonna group dominates on helvetesflya the djevleflota formation. we therefore distinguish only the djevleflota for mation on the new geological map (fig. 2), with underlying thin basal quartzites in eastern areas and basal conglomerates outcropping along the margin of vestfonna. djevleflota formation and basal quartzites and conglomerates flood et al. (1969) and ohta (1982~) showed the distribution of the persberget formation quartz ites in the eastern and western limbs of the rijpda len antiform and their relationship to underlying strata. ohta (1982~) recognised that, in the venesjoen synform on djevleflota, these quartz ites were underlain by a varied packet, estimated to a little over 1000 m in thickness, of shales and subordinate calcareous sandstones, quartzites and minor limestones; he therefore defined a new formation in this area. the succession is well preserved and primary structures are abundant (fig. 3). two major unconformities beneath the neoproterozoic murchisonfjorden supergroup 87 fig. 3 . sedimentary structures in the sandstones of the djevfig. 4 . basal conglomerates of the murchisonfjorden lerota formation. a . ripple marks. b. mud cracks. supergroup: locality close to the eastern margin of vestfonna (see fig. 2). clasts of quartzite, vein-quartz and dark meta volcanites in both a and b . in the western limb of the rijpdalen antiform, only about 100 m of the djevleflota formation is exposed beneath the persberget quartzites (thick ness probably reduced by normal faulting), and basal conglomeratic beds are locally preserved. conglomerates, described by winsnes, in flood et al. (1969, p. 37) from west of rijpfjorden, in the base of the persberget formation, may also be part of this murchisonfjorden basal unit. ohta (1982c, p. 47) referred to a “basal breccia” at the base of the persberget formation, west of brina, in southwestern rijpdalen and inferred that it marked the base of a separate sedimentary cycle within the murchisonfjorden supergroup. this unit probably also coincides with our basal murchisonfjorden conglomerate. beneath these basal conglomerates, in the west ern limb of the rijpdalen antiform, the litho logies are dominated by dark phyllites of the helvetesflya formation. in this area, the new mapping does not support the correlation (ohta 1982c) of these metasediments with the djevleflota formation. in the eastern limb of the venesjcien synform, the basal part of the djevleflota formation is poorly exposed; a few quartzite outcrops occur and the base is not seen. further to the northeast, this formation is exposed again beneath the persberget quartzites in the kvartsitthaugen syn form. here, the succession beneath the quartzites contains much green-grey cross-laminated silt and graded fine sandstone with quartzites at the base. however, the contact to the underlying helvetesflya dark phyllites and svartrabbane andesites is tectonic. the basal conglomerates of the murchison fjorden supergroup are of particular interest. in the field, a variety of clasts were recorded, includ ing red quartzites, vein quartz, dark phyllites, dark greenish mafic volcanic rocks, and light acid volcanics (fig. 4). in thin section, the meta volcanic rocks in the clasts are similar to those in the svartrabbane formation. relic fluidal and porphyritic textures are recognisable; quartz and feldspar are altered to quartz-sericite aggregates and the glass in the acid rocks has recrystallised to 88 d . g. gee & a . m . teben’kou form a fine-grained matrix. tourmaline-bearing clasts are conspicuous in these basal conglom erates. helvetesflya and svurtrabbane volcano sedimentary rocks two mappable formations occur below the mur chisonfjorden supergroup. the one (helvetesflya formation) is dominated by dark phyllites, locally, with volcanic intercalations; the other (svartrabbane formation) is mainly composed of andesites with subordinate rhyolites. the helvetesflya metasedimentary rocks are’ often relatively well preserved and “way-up” has been recorded locally. it may prove possible, with more detailed mapping, to beiher control the stra tigraphy, but the occurrence of tight to isoclinal folding and local inversion do not allow this on the present data base. the svartrabbane volcanic rocks are widespi-ead in the upper structural levels of the rijpdalen antiform in the eastern limb where they overlie the sedimentary units. simi larity of the latter to the brennevinsfjorden for fig. 5. svartrabbane formation volcanic rocks: a . agglom erates cut by granite sheet (bottom left). b. rhyolites with sedimentary clasts, probably derived from the underlying hel vetesflya formation. mation and the former to the kapp hansteen formation, noted by previous investigators, sup ports correlation with botniahalv~ya. a major unconformity separates these units. helvetesflya formation (dark phyllites) .-mon otonous dark phyllites, some of them black (1 2% graphite), dominate this phyllite formation. many of these lithologies have been described previously as shales or slates, but all that we have mapped have a strong, penetrative, fine-grained, sericitic schistosity and a superimposed crenu lation that is usually conspicuous. thin (a few centimetres) sandy intercalations are frequent and usually graded. thicker quartzites are rare in this formation. isoclinal folding makes thickness estimates very uncertain, but the formation is at least a few hundred metres thick; it is interpreted to be largely of turbidite origin. suartrabbane formation (uolcunites) .-the svar trabbane volcanic and associated sub-volcanic intrusions of central nordaustlandet have been described in some detail by teben’kov (1983) and ohta (1985). the fine-grained penetrative schistosity makes it often difficult to be sure whether the massive, volcanic rocks are extrusive or intrusive. however, in many outcrops, good exposures of transitions from volcaniclastic rocks to massive volcanites occur; in addition, the pres ence of sedimentary clasts in rhyolites and the intercalation of agglomerates with andesites, pro vide good evidence of extrusion (fig. 5 ) . the massive mafic rocks have been previously referred to as diabase and basalt, but have been shown by geochemical studies to be andesitic in composition (teben’kov 1983; ohta 1985). interbedded dark phyllites occur locally and sub ordinate quartzites are also present. ohta ( 1 9 8 2 ~ ) reported thin carbonate units in the contact between the svartrabbane and helvetesflya for mations. in 1995, a major unconformity was found to separate helvetesflya turbidites from svartrab bane volcaniclastic rocks. ohta (1982c, p. 50) referred to the presence of conglomerates sep arating these volcanic and sedimentary rocks at kjedevatna and inferred local unconformity. our 1995 mapping shows that the helvetesflya metasediments, with well-preserved sedimentary structures (e.g. graded bedding and cross-lami nation), are locally inverted and overlain by a thin (up to ca. 5 m) quartzite pebble conglomerate, two major unconformities beneath the neoproterozoic murchisonfjorden supergroup 89 passing up into rhyolites and andesites of the svartrabbane formation. granites (rijpdalen-winsnesbreen) red granites occur in a main massif in rijpdalen, developing a conspicuous thermal aureole in the host rocks to a distance of about 100 m from the contact. this rijpdalen granite (hjelle 1966; flood et al. 1969) occurs in the core of the rijpda len antiform and appears to be connected from the northern outcrop areas of inner rijpfjorden, southwards to the winsnesbreen granite near wahlenbergfjorden. the mineralogy of the granite is dominated quartz, albite and microcline with subordinate muscovite (up to 10%) and minor biotite. tourmaline is frequently present, particularly in association with pegmatites. the aureole mineralogy in the metasedimentary rocks is characterised by garnet and biotite, locally with staurolite; tourmaline also occurs commonly in the metasediments near the granite contact. shear zones and a semi-penetrative foliation with accompanying brittle deformation are generally present. augen gneisses (ringgisdalen) in the northern part of fig. 2, augen gneisses and augen granites are in contact with the helvetesflya rocks. the ductile foliation in the these igneous rocks is cut by the rijpdalen granite. contact relationships between the augen gneisses and the helvetesflya group have been observed in the area of fig. 2, north of svartrabbane and, further north (flood et al. 1969, pp. 105-112), in ring gisdalen (fig. i); in both areas, garnet, straurolite and andalusite crystallise in narrow thermal aureoles. these gneisses have been interpreted (flood et al. 1969) to be derived from granites that were intruded during deformation; the latter was probably of grenville age, based on recently presented u/pb zircon age-determination studies (johansson pers. com. 1994). deformation of the helvetesflya and svartrabbane formations flood et al. (1969) described the deformation of the helvetesflya and svartrabbane formations (their botniahalvoya group) to be more complex than that in the murchisonfjorden supergroup fig. 6 . folding in central nordaustlandet. a.upright s-plunging caledonian anticline in the djevleflotaformation. b. sideways closing precambrian folds in graded helvetesflya turbidites (length of hammer shaft 40 cm). strata; this conclusion is supported by our new work and ohta’s unpublished data ( y . ohta pers. com. 1996). major n-trending folds, such as the rijpdalen antiform and the venesjoen and kvartsitthaugen synforms, with their related high angle e-dipping cleavages, are apparently the only major structures to deform the neo proterozoic strata; they clearly fold an earlier generation of tight to isoclinal folds in the hel vetesflya and svartrabbane formations (fig. 6). these older folds, as shown by flood et al. (1969, pp. 85-87), have generally transverse axes (ca. wnw-ese) and a well-developed axial surface cleavage, with associated fine-grained schistosity. crenulation of the latter is generally due to the refolding by the n-trending rijpdalen antiform and related structures. beneath the basal mur chisonfjorden supergroup unconformity of east ern vestfonna, the axial surface schistosity dips nearly concordantly beneath the overlying con glomerates, implying that the folds in the older rocks were recumbent prior to caledonian deformation. 90 d . g . gee & a . m . teben’kov regional metamorphism a fine-grained schistosity, well defined by sericite and chlorite, characterises the helvetesflya metasedimentary rocks in most of the area of fig. 2. crenulation of this fabric resulted in partial reorientation of these phyllosilicates, but only minor recrystallisation. the latter is compatible with the evidence in the overlying shales of the murchisonfjorden supergroup of only incipient growth of sericite and chlorite in the cleavages. discussion and conclusions it can be concluded that a major unconformity separates the sedimentary rocks of the helvetesflya formation from the volcanic svar trabbane formation. a second unconformity occurs at the base of the overlying neoproterozoic strata of the murchisonfjorden supergroup. syn tectonic intrusion of early granites, during recum bent folding of the helvetesflya and svartrabbane formations was followed by post-tectonic intrusion of the rijpdalen-winsnesbreen granite. the latter is not seen to cut the murchisonfjorden supergroup sediments. the possibility exists that this granite may be caledonian in age; however, the presence of tourmaline in the clasts of the basal murchisonfjorden supergroup conglom erate and the association of this mineral with the aureole of the rijpdalen granite favours the interpretation that the rijpdalen-winsnesbreen granite is of grenville age. the ringgisdalen augen gneisses, derived from the syntectonic granites intruding the helvetesflya formation, have not as yet been investigated isotopically, but their age is probably pre-neo proterozoic. recent work by johansson (pers. com. 1994) has shown that a variety of megacrystic augen granite/gneiss, outcropping along the northwestern margin of austfonna (fonndalen, fig. 1) is of grenvillian (ca. 1050 ma) age; it may be related to the syntectonic intrusions referred to above. although granite clasts have not been found amongst the greenschist facies pebbles in the base of the murchisonfjorden supergroup of central nordaustlandet, it is worth noting that they are present in the vendian tillites, higher in the neo proterozoic succession (kulling 1934). a wide range of low-grade metasedimentary and meta volcanic rocks together with granite boulders have been described by krasil’seikov (1967, translated by harland et al. 1993, pp. 48-49) and by edwards (1976). an attempt was made by edwards and taylor (1976) to date these granites by the rb/sr method. no isochron was obtained, but an indication of a mesoproterozoic age was suggested; new studies are in progress. these granite clasts have been said by hjelle (in edwards & taylor 1976, p. 256) to be similar to the rijpdalen-winsnesbreen granite. the presence of granite boulders (up to 1 m in diameter) in the tillites of eastern wahlen bergfjorden and their smaller size further west prompted edwards (1976) to suggest that the source area lay within a few kilometres distance from the outcrops. without evidence for major facies changes in the murchisonfjorden supergroup, from the type area of western nord austlandet t o inner wahlenbergfjorden, this would suggest that latest proterozoic extensional faulting locally defined an eastern margin to the neoproterozoic basin, exposing basement to vendian erosion. the new work in central nordaustlandet, reported here, supports previous conclusions (gee et al. 1995) that caledonian tectonothermal activity on nordaustlandet is of a fundamentally different character than that found in western ny fnesland. within the neoproterozoic suc cessions, from eastern ny friedand, via murchisonfjorden and wahlenbergfjorden to rijpdalen, the folding is upright to westerly inclined and the recrystallisation in the associated cleavages is generally lower greenschist facies, with growth of fine-grained sericite and chlorite. only in the immediate contact to the planetfjella group and in the contact aureole t o the chy deniusbreen granite massif in southern ny fries land are higher greenschist facies conditions recorded in the neoproterozoic strata. the cale donian lower greenschist facies tectonothermal overprint may increase a little in grade towards the east, as suggested by k/ar and rb/sr mica ages (ohta 1994) in the underlying migmatites, but the possibility remains that the pre-devonian basement of the northern barents sea is essen tially a grenvillian complex, partially covered by a slightly deformed blanket of neoproterozoic and early paleozoic strata. ackttowledgements. -our field party in eastern nordaustlandet in 1994 included three students, j . gustafsson, j . nilsson and s. sandelin and geornorphologist l. sernenova. i n 1995, we were assisted by e. tagesson. w e thank them all for their two major unconformities beneath the neoproterozoic murchisonfjorden supergroup 91 contribution to the field investigations, at times under difficult wintery conditions. our work on nordaustlandet has been supported by the swedish polar research secretariat i n stock holm, thc polar marine geological expedition (pmge) in st. pctersburg and the swedish natural science research council. we also greatly appreciate excellent communication with norsk polarinstitutt and pmge colleagues and, particularly, discus sion and review of this paper by a. krasil’seikov and y. ohta. we also thank p. witt-nilsson and m. friberg for help with the final preparation of the diagrams. references edwards, m. b. 1976: sedimentology of late precambrian sveanor and kapp sparre formations at aldousbreen, wahlenbergfjorden, nordaustlandet. norsk polarinst. arbok 1974, 51-61. edwards, m. b. & taylor, p. m. 1976: a rb/sr age for granite gneiss clasts from the late precambrian sveanor formation, central nordaustlandet. norsk polarinst. arbok 1974, 255 258. flood, b., gee, d. g., hjelle, a . , siggerud, t. & winsnes, t. s. 1969: the geology of nordaustlandet, northern and central parts. norsk polarinst. skr. 146, 139. gee, d. g., johansson, a , , ohta, y., teben’kov, a. m., krasil’seikov, a. a , , balasov, y. a., larionov, a. n., gan nibal, l. f. & ryungenen, g. i. 1995: grenvillian basement and a major unconformity within the caledonides of nordaustlandet, svalbard. precambrian research 70, 215 234. hamilton, e . i & sandford, k. s. 1964: rubidium-strontium ages from some spitsbergen rocks. nature. 202, 1208-9. lon don. harland, w. b., hambrey, m. j. & waddams, p. 1993: vendian geology of svalbard. norsk polarinst. skr. 193, 1-150. hjelle, a . 1966: the composition of some granitic rocks from svalbard. norsk polarinst. arbok 1965, 7-30. hjelle, a. 1978: an outline of the pre-carboniferous geology of nordaustlandet. potarforsch. 48 (1/2), 62-77. krasil’scikov, a . a. 1967: tillitopodobnye parody severo vostoenoj zemli (tillite-like rocks of north east land). pp. 3&62 in sokolov, v. n. (ed.): materialy po stratigrajii spicbergena (data on the stratigraphy of spitsbergen), niiga , leningrad. kulling, 0. 1932: nbgra geologiska resultat frhn expeditionen till nordostlandet 1931. geol. foren. fork bd 54,13b145. stockholm 1932. kulling, 0. 1934: scientific results of the swedish-norwegian arctic expedition in the summer of 1931, part xi. the “hecla hoek formation” round hinlopenstredet. geograph. ann. 16 (stockholm), 161-254. lauritzen, 0 . & ohta, y. 1984: geological map of svalbard 1:500,000, sheet 4g nordaustlandet. norsk polarinst. skr. nr. 154-0, 14 pp. nordenskiold, a. e . 1864: geografisk och geognostisk beskrifn ing ofver nordostra delarne af spetsbergen och hinlopen strait. k . soenska vetensk. akad. handl. 4(7), 1-25. nordenskiold, a . e. 1866: utkast till spitsbergens geologi. k . suenska vetensk. akad. handl. 6(7), 1-35. ohta, y. 1982a: relation between the kapp hansteen for mation and the brennevinsfjorden formation in botnia halveya, nordaustlandet, svalbard. norsk polarinst. skr. 178, 5-18. ohta, y . 1982b: murchisonfjorden supergroup of lbgdya, northwest nordaustlandet, svalbard. norsk polarinst. skr. 178, 19-40. ohta, y. 1982~: lithostratigraphy of the hecla hoek rocks in central nordaustlandet and their relationships to the cale donian granitic-migmatitic rocks. norsk polarinst. skr. 178, 41-60. ohta, y. 1984: caledonian and precambrian history in svalbard: a review, and an implication of escape tectonics. tectonophysics 231, 183-94. ohta, y. 1985: geochemistry of the late proterozoic kapp hansteen igneous rocks of nordaustlandet, svalbard. polar res. 3 n.s., 69-92. ohta, y. 1994: caledonian and precambrian history in svalbard: a review, and an implication of escape tectonics. tectonophysics 231, 183-194. sandford, k. s. 1950: observations on the geology of the northern part of north-east land (spitsbergen). quart. j . geol. soc. lon. 15,461-93. london. sandford, k. s. 1956: the stratigraphy and structure of the hecla hoek formation and its relationship to a subjacent metamorphic complex in north-east land (spitsbergen). quart. j . geol. soc. lon. 112, 339-362. teben’kov, a. m. 1983: pozdnedokembrijskie magmatiteskie formacii severo-vostotnoj zemli (late precambrian mag matic formations of nordaustlandet). pp. 74-86 in krasil’s€ikov, a.a. (ed.): geologija spicbergena, p g o . sevmorgeologija, leningrad. molluscan assemblages associated with gigartina beds in the strait of magellan and the south shetland islands (antarctica): a comparison of composition and abundance research article molluscan assemblages associated with gigartina beds in the strait of magellan and the south shetland islands (antarctica): a comparison of composition and abundance sebastián rosenfelda,b, cristian aldeac,d, jaime ojeda a, johanna marambioa,b, mathias hünee, jesús s. troncosof & andrés mansillaa,b alaboratorio de macroalgas antárticas y subantárticas, universidad de magallanes, punta arenas, chile; binstituto de ecología y biodiversidad (ieb), santiago, chile; cdepartamento de ciencias y recursos naturales, universidad de magallanes, punta arenas, chile; dprograma gaia-antártica, universidad de magallanes, punta arenas, chile; efundación ictiológica, santiago, chile; fdepartamento de ecología y biología animal, facultad de ciencias del mar, universidad de vigo, vigo, spain abstract in this paper we evaluated the composition and abundance of molluscs associated with beds of the red algae gigartina, located in the south shetland islands (antarctic peninsula) and the strait of magellan (southern chile). during the summer season of 2013, samples were obtained by scuba diving using a 0.25 m2 quadrat, arranged randomly within the bed. we extracted a total of 15 quadrats per sampling site. for antarctic peninsula beds the most abundant species were the bivalve lissarca miliaris (233 individuals) and the gastropod laevilacunaria antarctica (94 individuals), while for strait of magellan beds the most abundant species was the polyplacophoran callochiton puniceus (36 individuals). comparative analysis between the two molluscan assemblages showed significant differences in the faunal composition between the antarctic peninsula and strait of magellan (f = 64.474; p = 0.0001). therefore, molluscs reported in both areas are characteristic of their respective biogeographic area. finally, gigartina species play an important role in the formation of patterns of abundance and diversity of the communities associated with them. keywords bivalvia; gastropoda; polyplacophora; algae beds; sub-antarctic; diversity abbreviations mbp: magellanic biogeographical province; nmds: non-metric multidimensional scaling ordination introduction in the high-latitude mbp (spalding et al. 2007), extensive macroalgae assemblages grow on hard substrates, between depths of approximately 0 and 20 m (mansilla et al. 2013). these communities of macroalgae are characterized mainly by the presence of species of the order laminariales, such as macrocystis pyrifera and lessonia spp. (mansilla et al. 2014; rosenfeld et al. 2014). in the antarctic peninsula, macroalgae communities are characterized by the presence of species of desmarestia (quartino et al. 2005). however, the rhodophyta algae gigartina skottsbergii is a characteristic species of the southern tip of south america (ramírez & santelices 1991) and west antarctica; it is therefore a species from cold-temperate to cold waters. in the sub-antarctic ecoregion this species is strictly sublittoral and grows on rocky substrate between 5 and 15 m deep (ávila et al. 1999). nevertheless billard et al. (2015) show that g. skottsbergii has two divergent, monophyletic clades that may correspond to two cryptic species, making gigartina sp. from antarctica endemic to this area. in antarctica it may live from the lower intertidal zone (pers. obs.) to shallow depths (wiencke & clayton 2002). gigartina skottsbergii forms dense sublittoral beds reaching biomasses of about 1773 g m–2 and densities of 15 individuals m–2 (ávila et al. 2004). besides being primary producers and ecosystem engineers (christie et al. 2009; torres et al. 2015), macroalgae beds are important for sustenance of biodiversity because they can alter local environmental conditions (stachowicz 2001), providing shelter, breeding places and/or food for many species of invertebrates and vertebrates (ríos et al. 2007; mansilla & ávila 2011; rosenfeld et al. 2015). molluscs are one of the most representative and studied groups worldwide of this algae–mollusc interaction (see vahl 1971; salas & hergueta 1986; sánchez-moyano et al. 2000; rueda & salas 2003; amsler et al. 2015; martin et al. 2016). in the mbp, molluscs are one of the most representative and diverse groups of benthic marine environments, with more than 397 species reported (linse 1999; valdovinos 1999). another important feature of magellanic molluscs is that 35% of species are endemic to the mbp (fortes & absalao 2011). among the molluscs, gastropods are the dominant group in terms of number of species, followed by bivalves (linse et al. 2006; clarke et al. 2007). clarke et al. (2007) recorded a total of 549 species of gastropods and 158 bivalves contact sebastián rosenfeld rosenfeld.sebastian@yahoo.com sekulovic, laboratorio de macroalgas antárticas y subantárticas, universidad de magallanes, casilla 113-d, punta arenas chile supplemental data for this article can be accessed here. polar research, 2017 vol. 36, 1297915 https://doi.org/10.1080/17518369.2017.1297915 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0003-3863-9750 https://doi.org/10.1080/17518369.2017.1297915 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1297915&domain=pdf distributed in the southern ocean. engl (2012) reported 336 species (plus 59 probably undescribed) of shelled gastropod and over 87 bivalves in antarctic waters. specifically, in the area of the antarctic peninsula, including the south shetland islands, the same authors recorded 130 species of molluscs, i.e., low species richness compared to that recorded in the mbp. in more detail, the sublittoral bottoms corresponding to the continental shelf were represented by 85 species of gastropod and 48 bivalves (linse et al. 2006). in addition, molluscs exhibited several levels of species richness between different areas of the southern ocean and adjacent areas, such as the mbp (linse et al. 2006). however, although in recent years efforts have increased to better understand mbp and antarctic molluscan biodiversity (linse 1999; griffiths et al. 2003; zelaya 2005; linse et al. 2006; clarke et al. 2007; aldea et al. 2011; pastorino 2016), few investigations have focused on the ecological interaction between macroalgae and antarctic molluscs (amsler et al. 2015). the main objective of this study was to characterize and compare molluscan assemblages associated with gigartina skottsbergii beds in the strait of magellan and gigartina sp. from the antarctic peninsula. the level of taxonomic affinity between the two provinces was also tested. material and methods the study area was localized at four sampling sites with g. skottsbergii and gigartina sp. beds: two in the strait of magellan – punta santa maria, located in tierra del fuego (53° 21ʹ s; 70° 27ʹ w); punta santa ana, located 60 km to the south of punta arenas (53° 37ʹ s; 70° 52ʹ w) – and in the antarctic peninsula: punta hanna (62° 39ʹ s; 60° 35ʹ w) and fildes bay (62° 12ʹ s; 58° 54ʹ w) (fig. 1). the samples were obtained by scuba diving between 1 and 10 m depth in quadrats of 50 × 50 cm, which were selected randomly within each bed. in each quadrat, all molluscs were collected, and also the substrate, where gigartina settled, was investigated. the rocks were subsequently scraped to ensure that all the species and specimens were collected. each macroalgal sample was placed in a plastic bag. in the laboratory, each sample was gently stirred to detach the associated fauna. once detached, the algae were removed from the bag and their fresh weight measured. fifteen quadrats were sampled during one dive at each site, resulting in 60 quadrats per site (4 sites × 15 quadrats). molluscs density was standardized to individuals per gram of algal fresh weight. to determine the faunal composition – and their comparison – univariate and multivariate biodiversity analyses were performed using the primer version 6.0 statistical package (clarke & gorley 2005). the univariate biodiversity measures calculated for each site were average species richness and average species abundance. spearman rank correlation analysis was conducted to determine the correlation between mollusc abundance and macroalgal fresh biomass. to show significant differences in abundance and species richness, including beds from both provinces, a nonparametric mann–whitney test was performed, using the statistica 7.0 statistical package (statsoft 2004; http://statistica.software.informer.com/7.0/). figure 1. sampling sites in the strait of magellan (a) and south shetland islands (b, c). 2 s. rosenfeld et al. http://statistica.software.informer.com/7.0/ the specific importance of each species at each sampling site was determined by the similarity percentage, simper (clarke 1993). once the most representative species of each group was known, complementary nmds (kruskal & wish 1978) was performed to analyse graphically which species contributed to the similarity of each of the study areas. the data were transformed to presence and absence, to reduce the contribution of abundant species and to equate rare species. to assess spatial differences in the structure of the assemblages, and as a measure of beta diversity, oneway permdisp analysis was carried out. dispersion was calculated as the average dissimilarity from individual observation units to their group centroid in multivariate space (anderson 2006). smaller dispersions among the assemblages depicted lower beta diversity. in order to evaluate the affinity of different taxonomic levels (species, genus, family and order) among the study areas, spatial replacement taxonomic levels (beta diversity) was calculated, i.e., a measure of difference in the composition between two or more assemblages (koleff 2005). to measure beta diversity, the presence and absence data of molluscan assemblages associated with gigartina in the magallanes area and antarctic peninsula were considered. in this way, the whittaker (1972) index was calculated: db = (sc/α) − 1, where sc is species richness recorded in a sector set and α is the average number of species in both areas. this index ranges from 0 (when samples are absolutely identical in species composition) and 1 (the samples are absolutely different in their species composition) (rau et al. 1998). finally, we used a linear dependence model to detect whether our sampling effort was able to estimate the total number of species of molluscs. this was designed to estimate species richness, depending on the number of samples (soberón & llorente 1993). all samples were randomized so as not to affect the shape of the curve (colwell & coddington 1994; moreno & halffter 2000). the simplex and quasi-newton estimation methods of the statistical package statistica 7 were used to estimate the coefficients of the nonlinear regression model. results we collected a total of 600 specimens and identified 599 individuals to species level. thirty-five species of molluscs in the classes polyplacophora, gastropoda and bivalvia were represented (table 1). of the total, 270 specimens were bivalves, corresponding to 11 species, 254 were gastropods, corresponding to 17 species, and 75 were polyplacophorans, corresponding to seven species. the remaining specimen (the bivalve hiatella sp.) was not assigned to a known species because we could not identify sufficient diagnostic characters. in terms of the number of species represented, gastropoda (17 species belonging to nine families) came out on top, followed by bivalvia (11 species belonging to six families) and polyplacophora (seven species belonging to four families). the bestrepresented families were littorinidae (four species) and phylobryidae (four species). for antarctic peninsula beds, the most abundant species were the bivalve lissarca miliaris (233 individuals) and the gastropod laevilacunaria antarctica (94 individuals), while for mbp beds the most abundant species were the polyplacophoran callochiton puniceus (36 individuals) and the gastropod fissurella oriens (22 individuals). molluscan assemblages from antarctic peninsula beds had a higher average abundance (21.9 ± 5.6 individuals) than mbp ones (7.05 ± 1.19), showing a significant difference between them (z = − 3.0837; p = 0.002). no significant differences in average species richness were evident (z = − 1.5959; p = 0.110) between antarctic assemblages (4.3 ± 0.3) and mbp ones (3.70 ± 0.4). we observed a good correlation between gigartina fresh biomass and the number of associated molluscs measured as total abundance (gigartina skottsbergii: r = 0.678, p < 0.05; gigartina sp.: r = 0.616, p < 0.05) (fig. 2). simper analysis showed that the cluster of antarctic peninsula beds showed an average similarity of 76.31%. meanwhile, the cluster of mbp beds presented an average similarity of 51.07%. the gastropods laevilacunaria antarctica and nacella concinna and the bivalve lissarca miliaris were the species that most contributed to the similarity of the antarctic peninsula assemblages (fig. 3), while for the mbp assemblages the polyplacophoran callochiton puniceus and gastropod fissurella oriens were species that most contributed to their similarity. nmds analysis (fig. 3) revealed that species of both clusters (antarctic and mbp) were located at a great distance (very low similarity between them). comparative analysis between the two molluscan assemblages (permdisp) showed significant differences in the faunal composition between the antarctic peninsula and strait of magellan (f = 64.474; p = 0.0001). turnover of the various taxonomic levels between the assemblages of the antarctic peninsula and strait of magellan presented a uniform pattern. the species and genus levels had the highest levels of turnover (βw = 1 and 0.8, respectively). in general, almost all taxonomic levels had high turnover values (βw > 0.5), except at the order level, which had a βw value of 0.1 (fig. 4). the species richness associated with the sampling effort was determined by a linear dependence model. for the antarctic peninsula, prediction constants were a = 5.3664 and b = 0.5370; therefore, the expected maximum richness (a/b) was 10 species with r2 = 0.98 and slope > 0.0000 (fig. 5(a)). this value is the same as that observed in the field (s = 10). finally, for the strait of magellan, prediction constants were a = 3.1585 and b = 0.1272; polar research 3 therefore, expected maximum richness (a/b) was 25 species with r2 = 0.97 and slope = 0.069 (fig. 5(b)). this value is the same as that observed in the field (s = 25). discussion this is the first comparative report of molluscan assemblages associated with the two gigartina species between the antarctic peninsula and strait of magellan. for the strait of magellan there had already been a previous report by rosenfeld et al. (2015) and for the antarctic peninsula one by amsler et al. (2015). the amount of mollusc species recorded in this work represents an average value similar to those reported in other studies carried out over the past 20 years in shallow subtidal rocky environments of the antarctic peninsula (table 2). in this regard, the work with the highest number of species (amsler et al. 2015) reported a total of 20 species of gastropod associated with gigartina sp., but that work mainly focused on species of the class gastropoda. however, in general all the works present a very similar mollusc species richness, being reports of assemblages with low species richness compared with molluscs from shallow subtidal habitats of the mbp, which have an average richness of 35 ± 13 species (rosenfeld et al. 2015). however, although molluscan assemblages from shallow bottoms of the antarctic peninsula have lower species richness compared to mbp ones, the level of endemism is higher in assemblages from antarctica. for example, of the 10 species recorded in figure 2. total abundance of mollusc per macroalgae biomass of gigartina in the four sampling localities: (a) populations the strait of magellan; (b) populations in the south shetland islands. table 1. systematic list of all mollusc species recorded, indicating their presence (+) in the beds of strait of magellan (ma) and the south shetland islands (si). class to family species ma si polyplacophora order chitonia ischnochitonidae ischnochiton stramineus (sowerby in broderip & sowerby 1832) + tonicina zschaui (pfeffer 1886) + callochitonidae callochiton puniceus (couthouy ms gould 1846) + chitonidae tonicia lebruni de rochebrune 1884 + tonicia chilensis (frembly 1827) + tonicia atrata (sowerby 1840) + mopaliidae nuttallochiton martiali (de rochebrune in de rochebrune & mabille 1889) + gastropoda order patellogastropoda nacellidae nacella deaurata (gmelin 1791) + nacella flammea (gmelin 1791) + nacella concinna (strebel 1908) + lepetidae iothia emarginuloides (philippi 1868) + ordervetigastropoda fissurellidae fissurella oriens sowerby 1835 + calliostomatidae margarella violacea (king & broderip 1832) + order littorinimorpha calyptraeidae trochita pileus (lamarck 1822) + littorinidae pellilitorina pellita (martens 1885) + laevilacunaria antarctica (martens 1885) + laevilitorina antarctica (e. a. smith 1902) + laevilitorina caliginosa (gould 1849) + ranellidae fusitriton magellanicus (röding 1798) + order neogastropoda buccinidae pareuthria cerealis rochebrune & mabille 1885 + pareuthria fuscata (bruguire 1789) + muricidae trophon pallidus (broderip 1833) + trophon nucelliformis oliver & picken 1984 + xymenopsis muriciformis (king & broderip 1832) + bivalvia order pteriomorphia mytilidae aulacomya atra (molina 1782) + mytilus e platensis d’orbigny 1842 + pectinidae zygochlamys patagonica (king & broderip 1832) + austrochlamys natans (philippi 1845) + phylobryidae philobrya sublaevis pelseneer 1903 + philobrya olstadi (soot-ryen 1951) + mysella subquadrata (pesenner 1903) + lissarca miliaris (philippi 1845) + order heterodonta hiatellidae hiatella sp + carditidae carditella naviformis (reeve 1843) + veneridae tawera elliptica (hupé in gay 1854) + gaimardiidae gaimardia trapesina (lamark 1819) + 4 s. rosenfeld et al. this study, 70% are endemic to antarctica, while of the 25 species recorded in the mbp only 28% are endemic to this biogeographic province (rosenfeld et al. 2015). these endemism values are related to biogeographic patterns established by griffiths et al. (2009), who posited that gastropods generally show a high level of endemism in all antarctic regions. in our study of six species of gastropod registered in antarctica, only the species laevilitorina caliginosa reached the mbp, having the chiloé islands as a northern distribution boundary (castellanos 1989). from our investigation of all previous work, through a full listing of mollusc species, there has been a total of 55 species of mollusc (one polyplacophora, 42 gastropoda and 12 bivalvia) inhabiting shallow rocky antarctic environments (0–30 m) (supplementary table s1). as in the work carried out by jazdzewski et al. (2001) and martin et al. (2016), the family with the most species in rocky shallow antarctic environments was littorinidae. of the total number of recorded species, nine belong to the littorinidae family, which could reflect that species of this family are more specialized to these extreme antarctic environments, where during the winter the sea freezes (wiencke & clayton 2002; waller et al. 2006). although, engl (2012) recorded eight species of prosipho (family: buccinidae): p. astrolabiensis (strebel 1908), p. crassicostatus (melvill & standen 1907), p. glacialis thiele 1912, p. enricoi engl 2004, p. harrietae engl & schwabe 2003, p. iodes oliver & picken 1984, p. mundus e. a. smith 1915, and p. turritus oliver & picken 1984, from rocky shallow waters, none of these species were recorded in the descriptive benthic studies of the last 22 years (supplementary table s1). in contrast, in the mbp the most representative family in shallow bottom assemblages was buccinidae, with more than 10 species (ríos et al. 2003; aldea et al. 2011), which may reflect the high diversity presented by this group in the mbp. in the linse’s species checklist of linse (1999), 27 species of buccinidae (as buccinulidae) for the mbp were reported. another gastropod family figure 3. nmds ordination of molluscan assemblages, showing arrangement of the species that most contributed to the similarity of each of their groups. cpu (callochiton puniceus), for (fissurella oriens), ist (ischnochiton stramineus), lan (laevilacunaria antarctica), lca (laevilitorina caliginosa), lmi (lissarca miliaris), mvi (margarella violacea), msu (mysella subquadrata), nco (nacella concinna), nfl (nacella flammea), pfu (pareuthria fuscata), tat (tonicia atrata), tlu (tonicia lebruni), tzc (tonicina zschaui), tpi (trochita pileus), tnu (trophon nucelliformis), xmu (xymenopsis muriciformis). figure 4. relationship between taxonomic levels and turnover thereof. polar research 5 representative in the mbp is calliostomatidae. linse (1999) used the name trochidae to group all species of calliostomatidae, reporting 16 species for the mbp. this group of gastropods is characterized as representative in subtidal studies of the strait of magellan (see ríos et al. 2003; aldea et al. 2011; rosenfeld et al. 2015). for example, calliostomatidae species such as margarella violacea have been reported as the most abundant (aldea et al. 2011), as in this study, in which m. violacea was one of the representative mbp species (fig. 6). regarding polyplacophorans, it should be noted that for the strait of magellan assemblage, six species were recorded inhabiting beds of gigartina, while for the antarctic peninsula we only recorded one species (tonicina zschaui), and generally in work on shallow environments of antarctica no polyplacophoran species are reported. therefore, polyplacophorans showed a drastic reduction in species richness compared to the mbp. the affinity of molluscs at species level between the strait of magellan and south shetland islands is quite low (linse et al. 2006). however, these authors mentioned that at higher taxonomic levels (e.g., families) the affinity increases. nevertheless, in this study we observed that even replacement at superfamily level between assemblages is high (βw = 0.6); therefore, molluscs reported in both areas are characteristic of their respective biogeographic area. finally, we note that in shallow-bottom systems in antarctica, disturbances caused by advance and retreat of the ice play a key role in structuring figure 5. linear dependence model to estimate the species richness associated with sampling efforts at sampling sites: (a) strait of magellan and (b) south shetland islands. table 2. number of mollusc species in antarctica recorded in works since 1994. we took into account studies where intertidal and sublittoral samples were collected (all studies with sampling depths less than 30 m were included and considered as ‘shallow water’). source depth gastropoda bivalvia polyplacophora total species martin et al. 2016 0 m 9 4 0 13 bowden 2005 8 to ca. 20 m 9 1 0 10 waller et al. 2006 0 to ca. 6 m 6 4 0 10 bick & arlt 2013 0 m 6 3 0 9 gambi et al. 1994 0 to ca. 16 m 7 1 0 8 jazdzewski et al. 2001 0 m 5 0 0 5 valdivia et al. 2015 0–30 m 4 3 1 8 amsler et al. 2015 6–16 m 20 0 0 20 aghmich et al. 2016 0 m 7 3 0 10 8 ± 1.7 2.1 ± 1.7 0.11 ± 0.4 10.3 ± 2.6 this record 0 to ca. 7 m 6 3 1 10 6 s. rosenfeld et al. communities (waller et al. 2006; valdivia et al. 2015). previous studies have shown that the highest diversities have been recorded in locations that undergo the greatest degree of physical disturbances by advancing ice (waller et al. 2006), since all taxa present in these localities inhabit more specific habitats under boulders rather than on them. the presence of populations of macroalgae on the rocky coast of the antarctic peninsula should also contribute considerably as habitats for a variety of sessile and mobile fauna, since the creation and complexity of habitats that form the different macroalgae species play an important role in the formation of patterns of abundance and diversity of the communities associated with them (torres et al. 2015; valdivia et al. 2015). these patterns were observed by martin et al. (2016) in populations of adenocystis utricularis and iridaea cordata around king george island, by amsler et al. (2015) in populations of eight dominant species of macroalgae and observed in this study in populations of gigartina species on both sides of the polar front. acknowledgments sr acknowledges the scholarship he received from chile’s institute of ecology and biodiversity (code icm p05-002) and the master of science in conservation and management of sub-antarctic ecosystems of the university of magellan. jm acknowledges the scholarship she received from chile’s institute of ecology and biodiversity (code pfb −23–2008) and the master of science in conservation and management of subantarctic ecosystems of the university of magellan. we are grateful for the support of the chilean antarctic institute (inach) for sample collections in antarctica. figure 6. representative species found in gigartina beds in the strait of magellan and south shetland islands. iem (iothia emarginuloides); for other abbreviated species names see labels of fig. 3. polar research 7 we thank the chilean navy ships ap-46 almte, oscar viel and ap-41 aquiles for the resources and support offered during antarctic field expeditions. the authors would like to thank the people of patagonia histórica s. a. for their valuable support to our fieldwork in punta santa ana. we thank dirk schories for the photo of nacella concina. the authors also thank two anonymous referees for their contribution in improving the manuscript. disclosure statement no potential conflict of interest was reported by the authors. funding this research was funded by chile’s national council for research in science and technology (conicyt) fondecyt program grant 1140940 to am, the millennium scientific initiative (grant p05-002 icm, chile) and the basal financing program (grant pfb-23, chile). ca would like to thank the program of direction of research and graduate studies of the university of magallanes (code 027520, pr-01vrac-14). orcid jaime ojeda http://orcid.org/0000-0003-3863-9750 references aghmich a., taboada s., toll l. & ballesteros m. 2016. first assessment of the rocky intertidal communities of fildes bay, king george island (south shetland islands, antarctica). polar biology 39, 189–198. aldea c., rosenfeld s. & cárdenas j. 2011. caracterización de la diversidad de moluscos bentónicos sublitorales en la isla carlos iii y áreas adyacentes, estrecho de magallanes, chile. (diversity characterization of subtidal benthic molluscs from carlos iii island and adjacent areas, strait of magellan, chile.) anales del instituto de la patagonia 39, 73–89. amsler m.o., huang y.m., engl w., mcclintock j.b. & amsler c.d. 2015. abundance and diversity of gastropods associated with dominant subtidal macroalgae from the western antarctic peninsula. polar biology 38, 1171–1181. anderson m.j. 2006. distance-based tests for homogeneity of multivariate dispersions. biometrics 62, 245–253. ávila a., cáceres j., nuñez m., camus p., pavez h., cortes h., gonzález j., tapia c., mejias p., cornejo s., romo h. & candia a. 2004. investigación y manejo de praderas de luga roja en la xii región. (research and meadow management of gigartina skottsbergii in the xii region.) valparaíso: fip (fund for fishing research) /ifop (institute of fishing promotion). ávila m., candia a., nuñez m. & romo h. 1999. reproductive biology of gigartina skottsbergii (gigartinaceae, rhodophyta) from chile. hydrobiologia 398/399, 149–157. bick a. & arlt g. 2013. description of intertidal macroand meiobenthic assemblages in maxwell bay, king george island, south shetland islands, southern ocean. polar biology 36, 673–689. billard e., reyes j., mansilla a., faugeron s. & guillemin m.-l. 2015. deep genetic divergence between austral populations of the red alga gigartina skottsbergii reveals a cryptic species endemic to the antarctic continent. polar biology 38, 2021–2034. bowden d. 2005. quantitative characterization of shallow marine benthic assemblages at ryder bay, adelaide island, antarctica. marine biology 146, 1235–1249. castellanos z.a. 1989. catálogo descriptivo de la malacofauna marina magallánica 4. mesogastropoda. (descriptive catalogue of marine magellanic malacofauna. 4. mesogastropoda.) la plata: buenos aires scientific research commission. christie h., norderhaug k.m. & fredriksen s. 2009. macrophytes as habitat for fauna. marine ecology progress series 396, 221–233. clarke a., griffiths h.j., linse k., barnes d.k.a. & crame j.a. 2007. how well do we know the antarctic marine fauna? a preliminary study of macroecological and biogeographical patterns in southern ocean gastropod and bivalve molluscs. diversity and distributions 13, 620–632. clarke k.r. 1993. non-parametric multivariate analyses of changes in community structure. australian journal of ecology 18, 117–143. clarke k.r. & gorley r. 2005. primer-e v6. user manual/ tutorial. plymouth: plymouth marine laboratory, natural environmental research council. colwell r.k. & coddington j.a. 1994. estimating terrestrial biodiversity through extrapolation. philosophical transactions of the royal society b 345, 101–118. engl w. 2012. shells of antarctica. hackenheim; germany: conchbooks. fortes r.r. & absalao r.s. 2011. biogeography and connectivity between western south american and antarctic marine molluscs. oecologia australis 15, 111–123. gambi m., lorenti m., russo g. & scipione m. 1994. benthic associations of the shallow hard bottoms off terra nova bay, ross sea: zonation, biomass and population structure. antarctic science 6, 449–462. griffiths h.j., barner d.k.a. & linse k. 2009. towards a generalized biogeography of the southern ocean benthos. journal of biogeography 36, 162–177. griffiths h.j., linse k. & crame j.a. 2003. southern ocean mollusc database: a tool for biogeographic analysis in diversity and ecology. organism diversity & evolution 3, 203–207. jazdzewski k., de broyer c., pudlarz m. & zielinski d. 2001. seasonal fluctuations of vagile bentos in the uppermost sublittoral of a maritime antarctic fjord. polar biology 24, 910–917. koleff p. 2005. conceptos y medidas de la diversidad beta. (concepts and measures of beta diversity.) in g. halffter et al. (eds.): sobre la diversidad biológica: el significado de las diversidades alfa, beta, gamma. (biodiversity: the meaning of alpha, beta, gamma diversities.) pp. 19–40. zaragoza: sociedad entomológica aragonesa. kruskal j.b. & wish m. 1978. multidimensional scaling. beverly hills, ca: sage publications. linse k. 1999. mollusca of the magellan region: a checklist of the species and their distribution. scientia marina 63, 399–407. linse k., griffiths h.j., barnes d.k.a. & clarke a. 2006. biodiversity and biogeography of antarctic and subantarctic mollusca. deep-sea research part ii 53, 985–1008. 8 s. rosenfeld et al. mansilla a. & ávila m. 2011. using macrocystis pyrifera (l.) c. agardh from southern chile as a source of applied biological compounds. revista brasileira de farmacognosia 21, 262–267. mansilla a., ávila m., ramirez m., rodriguez j.p., rosenfeld s., ojeda j. & marambio j. 2013. macroalgas marinas bentónicas del submareal somero de la ecorregión subantártica de magallanes, chile. (shallow subtidal benthic marine macroalgae from the magellan subantarctic ecoregion, chile.) anales del instituto de la patagonia 41, 49–62. mansilla a., rosenfeld s., rendoll j., murcia s., werlinger c., yokoya n. & terrados j. 2014. tolerance response of lessonia flavicans from the sub-antarctic ecoregion of magallanes under controlled environmental conditions. journal of applied phycology 26, 1971–1977. martin p., miloslavich p., yusbelly d., orteha i., klein e., troncoso j., aldea c. & carbonini a.k. 2016. intertidal benthic communities associated to the macroalgae iridaea cordata and adenocystis utricularis in king george’s island, antarctica. polar biology 39, 207–220. moreno c.e. & halffter g. 2000. assessing the completeness of bat biodiversity inventories using species accumulation curves. journal of applied ecology 37, 149–158. pastorino g. 2016. revision of the genera pareuthria strebel, 1905, glypteuthria strebel, 1905 and meteuthria thiele, 1912 (gastropoda: buccinulidae) with the description of three new genera and two new species from southwestern atlantic waters. zootaxa 4179, 301–344. quartino m.l., zaixso h.e. & boraso de zaixso a.l. 2005. biological and environmental characterization of marine macroalgal assemblages in potter cove, south shetland islands, antarctica. botanica marina 48, 187–197. ramírez e. & santelices b. 1991. catálogo de las algas marinas bentónicas de la costa temperada del pacífico de sudamérica. (catalogue of benthic marine algae of temperate pacific coast of south america.) santiago: pontifical catholic university of chile. rau j., zuleta c., gantz a., saiz f., cortes a., yates l., spotorno a.e. & couve e. 1998. biodiversidad de artrópodos y vertebrados terrestres del norte grande de chile. (biodiversity of arthropods and terrestrial vertebrates of norte grande, chile.) revista chilena de historia natural 71, 527–554. ríos c., arntz w.e., gerdes d., mutschke e. & montiel a. 2007. spatial and temporal variability of the benthic assemblages associated to the holdfasts of the kelp macrocystis pyrifera in the straits of magellan, chile. polar biology 31, 89–100. ríos c., mutschke e. & morrison e. 2003. biodiversidad bentónica sublitoral en el estrecho de magallanes, chile. (benthic sublittoral biodiversity in the strait of magellan, chile.) revista de biología marina y oceanografía 38, 1–12. rosenfeld s., aldea c., mansilla a., marambio j. & ojeda j. 2015. richness, systematics and distribution of molluss associated with the macroalga gigartina skottsbergii, in the strait of magellan, chile: a biogeographic affinity study. zookeys 519, 49–100. rosenfeld s., ojeda j., hüne m., mansilla a. & contador t. 2014. egg masses of the patagonian squid doryteuthis (amerigo) gahi attached to giant kelp (macrocystis pyrifera) in the sub-antarctic ecoregion. polar research 33, article no. 21636, doi: 10.3402/polar.v33.21636. rueda j.l. & salas c. 2003. seasonal variation of a molluscan assemblage living in a caulerpa prolifera meadow within the inner bay of cádiz (sw spain). estuarine coastal and shelf science 57, 909–918. salas c. & hergueta c. 1986. la fauna de moluscos de las concreciones calcáreas de mesophyllum lichenoides (ellis) lemoine. estudio de la diversidad de un ciclo anual. (the molluscan fauna of mesophyllum lichenoides [ellis] lemoine calcareous concretions. study of the diversity of an annual cycle.) iberus 6, 57–65. sánchez-moyano j.e., estacio f.j., garcía-adiego e.m. & garcía-gómez j.c. 2000. the molluscan epifauna of the alga halopteris scoparia in southern spain as a bioindicator of coastal environmental conditions. journal of molluscan studies 66, 431–448. soberón j. & llorente j. 1993. the use of the species accumulation functions for the prediction of species richness. conservation biology 7, 480–488. spalding m.d., fox h.e., allen g.r., davidson n., ferdaña z.a., finlayson m., halpern b.s., jorge m.a., lombana a., lourie s.a., martin k.d., mcmanus e., molnar j., recchia c.a. & robertson j. 2007. marine ecoregions of the world: a bioregionalization of coastal and shelf areas. bioscience 57, 573–583. stachowicz j.j. 2001. mutualism, facilitation, and the structure of ecological communities. bioscience 51, 235–246. statsoft. 2004. statistica for windows. computer program manual. tulsa, ok: statsoft inc. torres a.c., veiga p., rubal m. & sousa-pinto i. 2015. the role of annual macroalgal morphology in driving its epifaunal assemblages. journal of experimental marine biology and ecology 464, 96–106. vahl o. 1971. growth and density of patina pellucida (l.) (gastropoda: prosobranchia) on laminaria hyperborea (gunnerus) from western norway. ophelia 9, 31–50. valdivia n., díaz m.j., garrido i. & gómez i. 2015. consistent richness-biomass relationship across environmental gradients in a marine macroalgal-dominated subtidal community on the western antarctic peninsula. plos one 10, e0138582, doi: 10.1371/journal. pone.0138582. valdovinos c. 1999. biodiversidad de moluscos chilenos: base de datos taxonómica y distribución. (chilean mollusks biodiversity: taxonomic and distributional data base.) gayana 63, 111–164. waller c.l., barnes d.k.a. & convey p. 2006. ecological contrasts across and antarctic land–sea-interface. austral ecology 31, 656–666. whittaker r.h. 1972. evolution and measurement of species diversity. taxon 21, 213–251. wiencke c. & clayton m.n. 2002. synopses of the antarctic benthos. vol. 9. antarctic seaweeds. ruggell, lichtenstein: gantner. zelaya d.g. 2005. systematics and biogeography of marine gastropods molluscs from south georgia. spixiana 28, 109–139. polar research 9 https://doi.org/10.3402/polar.v33.21636 https://doi.org/10.1371/journal.pone.0138582 https://doi.org/10.1371/journal.pone.0138582 abstract introduction material and methods results discussion acknowledgments disclosure statement funding references a review of variability in the distribution and abundance of norwegian spring spawning herring and barents sea capelin ingolf rbttlngen r ~ t t i n g e n , i . 1990 a review of variability in the distribution and abundance of norwegian spring spawning herring and barents sea capelin. polar research 8, 33-42. the historic data on the fisheries on norwegian spring spawning herring and barents sea capelin show that the migration pattern and time of spawning havc changed for these species. furthei-morc, modern techniques like tagging, hydroacoustic ahundancc estimation and virtual population analysis have shown that the abundance, both of the adult and the immature parts of the population. fluctuates widely. predators (other fish, seabirds, sea mammals) of pelagic fish must have experienced corresponding fluctuations in food availability. ingolf r)ttingen, fiskeridirektoratets hauforskningsimtitutt, p . 0. box 1870 nordnes, n-5024 bergen, norway; february 1989 (reuised june 1989). there have been great changes in the abundance and stock structure of the pelagic fish species in northern waters. we have seen the collapse of the norwegian spring spawning and north sea herring stocks in the 1960s (dragesund et al. 1980; jakobsson 1985), and the icelandic and barents sea capelin stocks in the 1980s (vilhjalmsson 1983; tjelmeland 1989). the north sea herring stock and the icelandic capelin stock have recovered. the norwegian spring spawning herring is slowly recovering, but the barents sea capelin is still at a low level. these fluctuations in the pelagic fish stocks will certainly have large consequences not only for the fisheries which are dependent on them, but also for the whole ecosystem, including the organisms (other fish, marine mammals and seabirds) which are troph ically linked to these pelagic species. the collapse of fish stocks is often regarded as a phenomenon linked t o overfishing caused by the modern, highly efficient fishing fleets. overfishing has in several cases undoubtedly led to a decrease in the stock size of some pelagic species, e.g. the norwegian spring spawning herring in the late 1960s (dragesund et al. 1980). it has consequently been argued that overfishing is the main cause when seabird species fail to find sufficient food, and death due t o starvation occurs (lid 1981). however, the historical record of the fisheries indicates that there have occurred changes in abundance, migration and distribution of impor tant pelagic fish species many times in the past. the aim of the present paper is t o examine the variations that have taken place during the last two centuries with regard to the norwegian spring spawning herring and the barents sea capelin. fish migration it is well known that fish stocks, in particular the large pelagic ones, migrate from place to place. the migration will be a key factor determining the availability to predators and for the fisheries on the species in question. f e e d 1 n g a r e a s p a w n i n g -> n u r s e r y a r e a a r e a fig. 1. general pattern of fish migrations. (modified from harden jones 1968.) 34 i . rlttingen t h e concept of fish migration can b e simply visualized, as being triangular in pattern, with the spawning area, nursery area and adult stock at the three corners (harden jones 1968). this is shown in fig. 1. t h e currents are of major importance for the determination of the migration pattern. t h e young stages drift with the current t o the nursery ground. t h e spawning migration is often against the current, and spent fish return to the feeding grounds with the current. if t h e currents change their intensity or direction, this will obviously have a great impact o n t h e system by the carrying of larvae further away from their spawning fields. this can also have an influence o n such factors as growth rate and mortality. fig. 2 . norwegian spring spawning herring. distribution areas and migration routes prior to 1970. (from dragesund et al. 1980.) 7 5' 7 0' 65 60 distribution and abundance of norwegian spring spawning herring 35 jan hayen a bjornaya 0 20" 10' o 0 10" 20" fig. 3. norwcgian spring spawning herring. distribution arcas and migration routcs 1986-1988. lcgcnd as fig. 2. t h e following changes within t h e general fish abundance framework have been observed: 1. geographical changes in migration. from early times, the catch data for t h e fisheries 2 . changes in the timing of the migrations, resulta r e t h e only source for analysing changes in rela ing in changes in spawning time and feeding tive population abundance. from t h e middle of seasons. the last century, 'modern' communication 36 1. rmttingen fig. 4. norwegian spring spawning herring. percentage distribution of wintcr herring catchcs in different areas in 1908, 1938 and 1959-1964. (steamships, telegraph) could spread information on to the fishing fleet about any new developments in the distribution of fish. the fishing fleet had by then become relatively mobile, and could to a certain degree respond to such changes. there fore, a decreasing trend in the catch will probably reflect a decrease in abundance or a drastic change in the migration pattern (or both) of the species in question. in later years, one has been able to obtain estimates of the size of the norwegian spring spawning herring stock by the use of tagging (aasen 1958; dragesund & jacobsson 1963; anon. 1989) and vpa-techniques (virtual popu lation analysis) (dragesund & ulltang 1978; anon. 1987). the abundance of the barents sea capelin has been assessed by acoustic methods (dommasnes & r ~ t t i n g e n 1985) since 1972. distribution and abundance of norwegian spring spawning herring 37 norwegian spring spawning herring biological studies conducted over many years gradually led to the understanding of the migration routes of the norwegian spring spawn ing herring. fridriksson (1944) suggested a relation between the herring caught in summer and autumn off northern iceland and the herring which was caught on the spawning fields off west ern norway in winter. this was later confirmed by tagging (fridriksson & aasen 1950). in order to obtain more systematic information on these migrations, many investigations were coordinated by the international council for the exploration of the sea (ices) in the following years. sonar surveying was an important tool in this work, and by the end of the 1950s the various details of the migration routes which the herring followed had been mapped (devold 1963). the migration routes which were prevalent in the 1950s are shown in fig. 2. the locations of the main spawning sites have shifted. this can be deduced from the shifting locations of the winter herring fishery (a fishery on herring in the spawning season). fig. 4 shows that there is a northward shifting trend in the location of the main spawning fields from the beginning of this century up to the 1960s. the arrival of the herring in norwegian coastal waters as well as the actual spawning in the same period have been delayed year by year (fig. 5 ) , as seen from the date when the mature herring appears on or near the spawning grounds (first day of the winter herring catch). the actual first day of spawning will be a week or two later. such displacements in time and space have been described earlier (boeck 1871). fig. 6 shows the total catch of the fishery on spawning herring off the west coast of norway in the period 1755-1988. an absence of the fishery at the end of the eighteenth century and around 1880 indicates that the herring was absent from the traditional spawning grounds during these periods. the reason for the absence was obviously not due to overfishing, but it cannot be stated with certainty whether there was a change in the migration routes or a ‘natural’ change in abun dance. however, the decline in the fishery in the 1960s was almost certainly due to overfishing (dragesund et al. 1980). the disappearance of the herring from the spawning fields of western and northern norway would of course have had great effects on the whole ecosystem, including : i c : lp55 1 v 5 0 1 9 l 5 1 9 1 0 :735 1 9 3 2 1 7 2 5 1 9 1 0 1 9 1 0 1905 c 1 9 0 4 1 1 , i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ia 2 0 10 20 1 0 20 10 20 10 20 10 2 0 8ept-to c t 4n o v + o e c -.lc j a n *fee fig. 5. norwegian spring spawning herring. data of first catch of winter herring on or near the spawning fields. (modified from devold 1963.) the organisms dependent upon the herring, irre spective of it being due t o overfishing or natural causes. the size of the spawning stock back to 1950 (fig. 7) has been calculated by using virtual popu lation analysis (dragesund & ulltang 1978; anon. 1989). fig. 7 shows that there has been an increase in the stock since 1970. at present, the spawning stock size is estimated to be in excess of 1 million tons. this is mainly due to the recruitment of the strong 1983 year class to the spawning stock in 1987-1988. during this rebuilding phase, some biological features, such as the migration pattern, have changed compared to the time prior to the stock collapse (fig. 3). changes in the adult population will also be reflected in the immature part of the herring stock. after hatching, the larvae are transported northward with the currents system, and in the autumn the herring fry are distributed in the fjord 38 i . rqttingen w 1 2 c o 1100 1000 900 8 30 l a z 0 c 700 z 4 vl 3 0 600 500 loo 300 2 00 100 1750 60 70 00 90 1800 10 20 30 lo 50 60 70 80 90 ¶900 10 20 30 lo 50 60 7 0 80 9 0 fig 6. norwegian spring spawning herring. catch of wintcr hcrring sincc 1755 and coastal areas of western and northern norway and in the barents sea. there are of course no data on distribution and drift of larvae and fry from earlier times, but an example of changing larval abundance with changing spawning stock size can be illustrated by the recorded larval abun dance at the time of the stock collapse. when the spawning stock was at a minimum in 197c-1972 (and thus almost absent from the traditional spawning sites of western norway) it can be seen from fig. 8 that the larvae practically disappeared from the northern transportation system. the 1950 1960 1970 1980 1985 abundance of herring fry in the autumn will also vary considerably from year to year, and fig. 9 barents sea nursery area in recent years. mlo r d 8 . 6 z 0 . c 4 2 . year ~ i ~ , 7, ~~~~~~i~~ spring spawning herring. size of spawning the scale of this variability in the stock 1950-1987. distribution and abundance of norwegian spring spawning herring 39 68 65 64 62' 68' 66' 64' fig. 8 . norwegian spring spawning herring larval distribution (numbers indicate number of larvae per metre of surface) in april 1968-1977 (h. bjorke unpublished). barents sea capelin compared with the herring, the historical data on long-term fluctuations of capelin are few. this is due t o the fact that there was no large scale fishery on capelin until the end of the 1950s. however, when the capelin migrated towards the coast to spawn, they were followed and preyed on by young cod. these immature cod were the basis for a winter cod fishery off finnmark and northern troms. there is a historical record of this fishery starting at the beginning of the last century. this record shows that there was no cod fishery in the period 1828-1840 (solhaug 1976) or in 1938-1942 (mgller & olsen 1962). the absence of spawning capelin on the coast, due to changes in abundance or spawning areas, has been given as the reason for the cessation of the winter cod fishery in these periods. furthermore, there was no spawning capelin off the coast in 1962 and very little in 1963 (olsen 1968). following the stock collapse in 1985-1986, the amount of spawning capelin in 1987 and 1988 was negligible compared to earlier years. hamre (1988) argues that the periods 1938 1942 and 1962-1963 were characterized by the occurrence of strong herring year classes in the preceding years. competition and probable pre dation of herring on capelin larvae and fry 40 1. rlrtingen 1983 . l . . . . . ... . . . . . . . . . . . . . . . . . .. n' . a .. . . ..... :a:* . . . . . 9 * . . . . 0 fig. 9. norwegian spring spawning herring. 0-group distribution in the barcnts sea in august 1983 (above) and in august 1986 (below). sampling stations indicated, cross hatching denotes dense recordings, single hatching dcnotes scattered recordings. resulted in poor capelin year classes and the absence of spawning capelin was thus due to decreased capelin abundance in these periods. in contrast to what happened to the norwegian spring spawning herring stock, the fishery is not believed to be the single, major factor of the capelin stock collapse in 1985-1986. the capelin fishery had in the late 1970s and the beginning of the 1980s been regulated on the assumption that the predation on capelin was constant from year b a r e n t s s e a c a p e l i n 11 stock s i z e 1 1 9 7 0 1975 1980 1985 1988 fig. 10. acoustic stock estimates and catch of barents sea capelin 1970-1988. to year. however, in the middle of the 1980s this predation increased dramatically due to a large stock of young cod. tjelmeland (1989) argues that this increased predation was the decisive element of the capelin stock collapse. there are very few quantitative data about stock abundance prior to 1970. after 1970, a large effort has been put into investigations of this stock. acoustic abundance estimates of the cap elin have been made each year since 1972 (dommasnes & rottingen 1985). the estimates of the capelin stock are shown in fig. 10, and it is apparent that the stock has fluctuated appre ciably. there has also been a corresponding shift in eastern and western location of spawning grounds. so-called western, i.e. areas west of the north cape, or eastern (east of the north cape) spawning has been observed recently. in earlier periods the catch statistics for the winter cod fishery show that the main part of the winter cod fishery, and thereby probably the largest capelin concentrations, in some years took place west of the north cape, and in some years east of the north cape. there are also recorded changes in time of spawning (mdler & olsen 1962). these data do distribution and abundance of norwegian spring spawning herring 41 fig. 11. barents sea capelin. autumn distribution of capelin in 1972, 1975, 1981 and 1985 from hydroacoustic surveys. numbers denote tons per square nautical mile. not, however, show such a clear trend as for the norwegian spring spawning herring. there have been detailed systematic inves tigations on the summer feeding grounds of this stock since the beginning of the 1970s. these investigations show that in some years the summer feeding grounds are located in the eastern part of the barents sea, in other years there is a more western distribution (fig. 11). these fluctuations in the adult stock will, as was the case for norwegian spring spawning herring, be reflected in the amount and distri bution of the spawning products, larvae and fry. this variation is illustrated in the distribution of 0-group capelin in august 1980 and august 1987 (fig. 12). concluding remarks the present paper has shown that the adult and immature stocks of two very important pelagic stocks in northern waters, norwegian spring spawning herring and barents sea capelin, have fluctuated considerably in distribution and abun dance over the last two centuries. these large variations must repeatedly have had profound consequences for the ecosystems both in the 42 i. rlttingen --.p?i' p ' 1980 . . . . . . . . . . . . . . . . i... ........... fig. 12. barents sea capelin. 0-group distrihution in the barents sca in august 1980 and in august 1987. legend as in fig. 9. norwegian and barents seas. the author has not speculated to any extent about the underlying reasons for these changes. these reasons are com plex, and one has t o take into account factors from both the biological and physical regimes, and sometimes, but not necessarily always, human activity. references aascn, 0. 1958: estimation of the stock strength of norwegian winter herring. j . coun. int. explor. mer 24, 95-1 10. anon, 1987: report of the working group on atlanto-scandian herring and capelin. court. meet. int. coun. e x p b r . sea 1987 (aassess. 8), 1-57 (mimeo.). anon. 1989: report of the atlanto-scandian herring a n d capelin working group. coun. meet. inf. coun. explor. sea i989 (assess. 7), 1-48 (mimeo.). boeck, a . 1871: omsildenogsildefisket, navnligomdct norske vaarsildfiskc. pp. 1-131 in indberetning ti1 departemenlet f o r det indre. christiania (in norwegian). devold, f. 1963: life history of the atlanto-scandian herring. rapp. p.-u. reun. cons. int. explor. mer 154, 98-108. dommasnes, a . &! rdttingen, i . 1985: acoustic stock measure ments of thc barents sea capelin 1972-1984. a review. pp. 45-108 in gjmsaeter, h. (cd.): proc. soviet-norwegian sytnp. barents sea capelin, bergen-norway, 1 6 1 7 august 1984. institute o f marine rescarch, bergen. dragesund, 0. &!jacobsson, j . 1963: stock strengths and rates of mortality of the norwegian spring spawnings as indicated by tagging experimentsin icelandic waters. rupp. p.-o. reun. cons. int. explor. mer 154, 83-90. dragesund. 0. & ulltang, 0. 1978: stock size fluctuation and rate of exploitation of the norwegian spring spawning herring. 1950-1974. fiskdir. skr. ser. haounders. 16, 315 337. dragesund, o., hamre, j . &! ulltang, 0. 1980: biology and population dynamics of thc norwegian spring spawning herring. rapp. p . u . reun. cons. int. explor. mer 177. 43 71. fridriksson, a . 1944: nordurlandssildin (the hcrring of the north c o b s ~ o f iceland). ril fiykideild. i . 338 p p . fridriksson, a . & aasen, 0. 1950: the norwegian-icelandic herring tagging experiments. rep. 1. fiskdir. s k r . ser. huvunders. 9, 1-43. hamre, j . 1988: some aspects of the interrelation between the herring in the norwegian sea and the stocks of capelin and cod in the barents scas. coun. meet. int. coun. explor. sea 1988 (h.42), 1-15 (mimco.). harden jones, f. r. 1968: fish migration. edward arnold, london. 325 pp. jakobsson, j . 1985: monitoring and management o f the north east atlantic herring stocks. cun. j . fish. aqucrt. p i . 42 (supp. i ) , 207-221. lid, g . 1981: reproduction of the puffin on rdst in the lofoten islands in 19641980. fauna norv. ser. c, cinclus 4 , 30-39. mdller, d. & olsen, s . 1962: lodda og loddefisket. fiskets gang 3, 27-35 (summary in english). olsen, s . 1968: some results of the norwegian capelin inves tigations 1960-1965. pp. 1%23 in blacker, r.v. (ed.): sym posium on the ecology of pelagic fish species in arctic waters and adjacent seas. rapp. p . v . reun. cons. int. explor. mer 158. solhaug, t. 1976: de norske jiskeriers hivlorie 1815-1880. univcrsitetsforlaget, oslo. 770 pp. (in norwegian), tjclmeland, s . 1989: cod-capelin interactions in the barents sea: a new light on past management of capelin. con tributions to ices. symposium on multispecies models rele vant to the management of living resources, the hague, 1989 (in press). vilhjalmsson, h. 1983: biology, abundance cstimates and man agements of the icelandic stock of capelin. rit. fiskideild. 3 , 15s-181. ecophysiological studies on arthropods from spits berg en tore aunaas, john g. baust and karl erik zachariassen aunaas, t . , baust, j. g. & zachariassen, k. e. 1983: ecophysiological studies on arthropods from spitsbergen. polar research 1 a s . , 235-240. the cold-hardiness, high temperature tolerance and metabolic activity of summer specimens of staphylinid beetles ( a t h e t a graminicola), collembolans (onichiurus g r o e n l a n d i c w ) , spiders (erigone arcrica), and prostigmatid mites (molgus l i n o r a l b ) from spitsbergen were investigated. the animals displayed cold hardiness and haemolymph melting points within the normal ranges for summer insects from temperate regions, but were less tolerant to high temperatures. haemolymph from spiders and from one species of collembolans ( l s o r o m a sp.) was found to contain thermal hysteresis factors. the beetles. collembolans. and mites were found to have oxygen consumption rates above the values of their relatives in other climatic zones, whereas the spiders had values within the range of temperate arachnoids. the study supports the view that polar arthropods have activation energy values lower than those of temperate animals. tore a u n a a s and karl erik zachariassen, deparrmetir of z o o l o g y , uniuersiry of trondheim. 7055 dragvoll. n o r w a y ; john g. baucr. deparrmenr of biology, unioersiry of h o u s ~ o i i , h o u s t o n . texas 77004, u . s . a . introduction several studies have revealed that mammals and birds from spitsbergen a r e physiologically highly specialized (krog et al. 1976; grammeltvedt & steen 1978; ringberg & reimers 1982). these specializations apparently reflect adaptations to the prevailing climatic conditions on the islands. although the invertebrate fauna at spitsbergen is fairly well known ( s ~ m m e 1979). very few studies have been made on the possible physio logical adaptations of the spitsbergen arthropods. the purpose of the present study was to inves tigate the cold-hardiness and possible metabolic adaptations of the terrestrial arthropods in this area. materials and methods the investigations were carried out o n insects and arachnoids collected in the vicinity of longyear byen in mid j u n e 1981 and in the vicinity of n y h e s u n d at the end of july 1982. the animals were collected under stones o n the tundra or in the rich vegetation below bird cliffs in kongsfjor den. the animals were kept in small glass tubes at temperatures ranging from + 2 to -2°c for u p to ten days before they were used in the experi ments. t h e experiments were carried out partly in a temporary laboratory established in a cabin in adventdalen and partly at the research station of the norwegian polar research institute in ny-alesund. the supercooling points of the animals were determined by using the arrangement shown in fig. l a . t h e animals were attached t o a dm thermistor probe of a g r a n t temperature recorder by means of silicone grease. they were cooled inside a thermos bottle containing a cold mixture made from snow and caci2.6h20. t h e super cooling points were indicated as small inflections on the temperature curve, d u e to the release of the heat of fusion of water freezing. the melting points of the haemolymph of the animals were determined by using a clifton nanolitre osmometer, in which t h e melting pro cess of 3 0 n l samples of haemolymph could be observed in a microscope, while the temperature of the samples was regulated with an accuracy of 5 0.001"c. t h e temperature at which the last tiny ice crystal disappeared during slow warming of the sample was taken as the melting point. samples of haemolymph were obtained from the animals by puncturing the cuticle with a thin glass capillary and sucking the haemolymph into the capillary by means of the capillary forces. when a sufficient amount of haemolymph could not be obtained from o n e animal, the samples were pooled from several individuals. t h e haemo lymph samples were handled as described by zachariassen et al. (1982). 236 t. aunaas, j . g. baust and k . e. zacharias3 ;en / a b fig. i . a : arrangement of instruments for determination of supercooling points. b-animal. c.m.*old mixture. t% thermos. t.r.-grant temperature recorder. b: arrangement of instruments for determination of oxvgen consumption. %animal. a-co? absorber (10% solution of koh). r respirometer. s.l.-styrofoam lid. t-thermometer. ts-ther mos. w-water. f-indicator fluid the presence in t h e haemolymph of thermal hysteresis factors ( t h f ) , which have the ability to separate the temperature of ice crystal growth upon cooling of a frozen sample from t h e melting point. was investigated o n the clifton nanolitre osmometer as described by zachariassen & husby (1982a). t h e haemolymph samples were cooled with a tiny ice crystal present, and the temperature at which a rapid growth of the ice crystals was observed was taken as the hysteresis freezing point (hfp). the upper lethal temperatures of the animals were determined by exposing them to tempera tures increased in steps of 5°c until they showed abnormal behaviour (uncoordinated walking) or died. the animals were exposed t o each temper ature for 1 0 m i n . t h e experiments were per formed with the animals kept within small glass tubes which were immersed in water baths of the desired temperature. t h e oxygen consumption of the animals was measured a t different temperatures by using engelmann constant pressure respirometers, the inner capillary diameter of which is 0.5 mm (engelmann 1963). i n order t o obtain constant temperatures, the respirometers were immersed in waterfilled thermos bottles as shown in fig. l b . u p t o five animals were used in each respiro meter. a piece of paper was put into the respi rometers t o give the animals a convenient sub stratum and thus keep their activity at a low level. in order t o adjust for possible variations in tem perature o r atmospheric barometric pressure, an empty respirometer was used as a blank instru ment. t h e oxygen consumption was calculated at n t p and in relation to t h e fresh body weight of the animals. since n o balance was available in the field lab oratories, the fresh body weight had t o be deter mined by means of an indirect method after return to the university. some of the animals, particu larly the collembolans, became seriously dehy drated during t h e respirometer experiments, and the fresh body weight was estimated from the dry weight. immediately after the experiments the animals were transferred t o dry, clean glass tubes, in which they were dried t o a constant weight at +60"c. t h e relative water content of each species was determined o n specimens that were trans ported alive to the university of trondheim, and these data were used to estimate the fresh body weights of the experimental animals from the dry weight values. t h e relative water content of the animals varied from about 7 5 % for the collem bolans and mites t o about 61% for the beetles. the oxygen consumption was calculated in rela tion t o the estimated initial fresh body weights. results the melting points, hysteresis freezing points, supercooling points, and upper lethal tempera tures of the animals are shown in table 1. t h e data reveal that all species investigated had haemolymph melting points in t h e range of from ecophysiological studies on arthropods 237 table i . melting points, hysteresis freezing points, supercooling points and upper lethal temperatures of spitsbergen arthropods. values are mean ? sd, and the number of measurements are given in parentheses. ~ melting hysteresis point freezing point species (“c) (“c) molgus littoralis -1.02 -1.02 hypogastrura sp. erigone arctica -1.06 -1.31 onichiurus groenlandicus -0.31 -0.31 isotoma sp. -0.75 -0.90 atheta graminicola -1.03 -1.03 supercooling point (“c) upper lethal temperature (“c) -6.4 t 0.6 (6) -6.0 2 1.1 (7) -6.7 t 1.7 (11) -7.1 5 1.7 (10) -5.3 2 1.1 (7) +35+40 +30+35 +30+35 table 2 . oxygen comsumption (mm3 o2/g.min) of spitsbergen arthropods at different temperatures. values are mean 2 s e . the numbers of measurements are given in parentheses. species 0 temperature (“c) + 5 + 10 + 15 erigone arctica 1.1 2 0.4 (2) 2.1 2 0.3 (7) 1.7 2 0.5 (4) 3 4 2 1.2 (4) onichiurus groenlandicus 5.9 2 0.8 (5) 9.9 2 2.4 (6) 14.0 ? 5.8 (5) molgus littoralis 1.4 ? 0.3 (3) 5.0 % 1.5 (3) 6.7 ? 1 . o (3) 14.0? 1.4 (3) atheta graminicola 5.4 t 1.3 (3) 10.6 2 1.1 (4) 13.7 t1.8 (4) 26.8 -t 1.3 ( 4 ) about -1.2 to about -0.3”c. in most of the species the freezing point corresponds to the melt ing point, indicating that thf are absent from their haemolymph. however, the haemolymph of the spiders and one species of collembolans (isotorna sp.) showed a moderate hysteresis, revealing the presence of thf in the haemolymph of these species. all species had supercooling points within the range of from -5 to -7°c. none of the animals were tolerant to freezing, and thus, the super cooling points correspond to the lower lethal tem peratures of the animals. the upper lethal tem peratures range from +30 to +35”c for the collembolans and the beetles, and from +35 to +40”c for the spiders. the oxygen consumption values of each species at different temperatures are listed in table 2. the results show that the mites, collembolans, and beetles have an oxygen consumption con siderably higher than that of spiders. in order to study the temperature dependence of the metabolic processes more exactly, the data are plotted in an arrhenius plot (fig. 2). the arrhenius plot is based on the arrhenius equation m = a . e-drjr.t, where m is the metabolic rate (= oxygen consumption), a is a constant, p is the activation energy, r is the universal gas constant, and t is the temperature in o k . the arrhenius equation can be expressed as in m =in a (@) (1/t), where 1n m and 1/t are used directly in the plot by being linearly related variables. the terms in a and -p/r represent the ordinate inter ception point and the slope, respectively, and can be determined by calculating the linear regression line of the values of in m and 1/t. 3 5 3 0 2 5 ~ 2 0 x c 1 5 1 0 0 5 0 3 50 3 55 3 60 3 65 i / t i o k ~ ~ 1031 fig. 2 . arrhenius plot of the metabolic rates of four species of terrestrial arthropods from spitsbergen. the lines are linear regression lines, calculated as described in the text. 238 t . aunaas, j . g. baust and k . e . zachariassen table 3. qlo values and activation energy values of spitsbergen arthropods. the correlation coefficient ( r ) and the number of observations for each species ( n ) are also given. species activation energy qiil (kcab'mol) r n erigone arctica 1.9 6.9 -0.41 17 molgus littoralis 3.4 21.1 -0.91 12 onichiurus groenlandicus 2.3 9.8 -0.41 16 atheta graminicola 2.8 16.6 -0.92 15 the activation energy is calculated by multi plying the slope of the regression line by the universal gas constant (1.98 cal/mol."k). the val ues for the activation energy of the spitsbergen arthropods are given in table 3, together with the q l o values of the oxygen consumption. the data show that the activation energy vanes from about 7kcal/mol for the spider to about 21 kcay'mol for the mite. the q l o values vary from 1.9 for the spider to 3.4 for the mite. the values for the insect are between these extremes. discussion the observed melting points of the haemolymph of the spitsbergen arthropods (-1.2 to -0.3"c) are typical for insects and spiders lacking accu mulated polyols in their body fluid (zachariassen 1980). this conforms well with the observed supercooling points (-5 to -7°c). which are in the range characteristic of temperate summer adapted insects ( s ~ m m e & conradi-larsen 1977; zachariassen 1980). thus, the summer insects at spitsbergen seem to be similar to summer insects in temperate and tropical regions. this pattern appears to be disturbed by the presence of thermal hysteresis factors (thf) in the haemolymph of the spiders and in one species of collembolans. the latter observation may sug gest that several species of the spitsbergen arthro pods are able to survive prolonged exposures at moderately low subzero temperatures in the sum mer, even when in direct contact with external ice (zachariassen & husby 1982b). studies by duman (1977, 1979) have revealed that the levels of t h f vary considerably over the year. from moderate levels or absence during the summer, to a hysteresis range of up to about 6°c in the winter. since the spitsbergen arthropods are likely to spend an extremely long period in a hibernating state, those which are sensitive to freezing probably depend heavily on thf to stabilize the unfrozen state and thus avoid a lethal freezing. consequently, the t h f levels of hiber nating spitsbergen arthropods are likely to be considerably higher than those observed in the summer specimens. furthermore, high levels of t h f may well be present during the winter in species lacking such substances in the summer. block & young (1978) found that antarctic cryptostigmate and mesostigmate mites had oxygen consumption rates higher than those of temperate species, whereas the oxygen consump tion of prostigmate mites was lower than the values of temperate mites. block (1981) obtained results indicating that sub-antarctic beetles have oxygen consumption rates somewhat below the values found in alpine temperate species (hbgvar & bstbye 1974), but that sub-arctic collembolans had rates which were somewhat higher than those of collembolans from temperate alpine regions (conradi-larsen 1974). in order to compare the oxygen consumption of the spitsbergen arthro pods with the values of arthropods from other i 1 0 0 e m . 0 e a r r z g 1 0 5 q z 0 u 7 3 1 t i i + 5 r 1 0 * i 5 temperature i " c \ fig. 3. semilogarithmic plot of the oxygen consumption of arachnids from spitsbergen and other regions as a function of temperature. --: spitsbergen spiders erigone arctica (0) and mites molgus linoralis ( 0 ) ; ---: temperate zone spiders from finse (line a) (hhgvar & 0stbye 1974; steigen 1976) and tem perate cryptostigmatid mites (line b) (young 1979); -: antarctic mite (young 1979). the lines are linear regression lines. the lines representing values for spitsbergen animals are calculated from the individual values forming the basis for the data in table 2, whereas the other lines are calculated from the mean values tabulated in the articles referred to. the bars represent se and the number of parallel measurements are indicated on the top of each bar. ecophysiological studies on arthropods 239 deviating results obtained for the spiders may mean that these animals survive in the area due to other strategies, such as reduced development rate and ability to complete their development over several years. it has also been speculated whether a low oxygen consumption rate may cause more energy to be invested in growth, and thus that animals with a low oxygen consumption rate in fact grow and develop faster than animals oxidizing their food at a high rate (block & young 1978). how ever, it should be kept in mind that protein syn thesis and growth also require energy, and that a high growth rate is likely to be accompanied by a high rate of oxygen consumption. considerably more data are needed on the biological features of the animals and the climatic conditions under which they live, before firm conclusions regarding the physiological adaptations of the terrestrial invertebrates can be drawn. young (1979) and block & young (1978) cal culated the activation energy of different ant arctic and sub-antarctic arthropods, and found that the values were generally within the lower part of the range of values found for temperate animals. these authors concluded that the acti vation energy values seem to vary systematically with the prevailing temperature in the habitat of the animals. figure 5 shows the values of acti vation energy of spitsbergen arthropods, plotted in frequency distribution histogram, together with values of temperate, alpine temperate, sub-ant arctic, and antarctic arthropods. the spitsbergen animals seem to have activation energy values in the lower range, quite similar to the antarctic arthropods studied by block and young. more over, measurements carried out on tropical desert insects have shown that these insects have a + z t 6 100 2 i i 0 0 z w > 0 0 .5 .i0 +15 temperature ( o c i fig. 4. semilogarithmic plot of the oxygen consumption of insects from spitsbergen and other regions as a function of temperature. -: spitsbergen collembolans onichiurus groen h d i c w (0) and staphylinid beetles arheru gruminicolu (0); beetles (line b) (block 1981); ---: alpine temperate zone beetles (line c) (five species from finse studied by hbgvar & bstbye 1974) and alpine temperate zone collembolans (line d) (two species from finse studied by conradi-larsen 1974); _ _ : two species of curculionid beetles from mount kenyz (zachariassen, unpublished). the bars represent se and the number of parallel measurements are indicated on the top of each bar. ...... . sub-antarctic collembolans (line a) (block 1981) and regions, the values have been plotted together in figs. 3 and 4. figure 3 shows that erigone spiders from spits bergen have oxygen uptake rates which are lower than the values of temperate alpine spiders from the finse high mountain plateau in norway over most of the temperature range, but which agree fairly well with the temperature range where the spitsbergen spiders perform their activity in nature, i.e. 0 +5"c (personal observations). mites from spitsbergen, on the other hand, have oxygen consumption rates considerably higher than those of temperate mites: these results con form with those obtained by young (1979). figure 4 shows that the spitsbergen collem bolans and beetles have oxygen consumption rates considerably above the values of insects from other regions. it is tempting to interpret these results to mean that the spitsbergen insects are active at relatively low temperatures, and that they have to increase their metabolic rate in order to complete their development within the rela tively short summer period. the somewhat i n i 9 6 3 4 m 2 0 15 20 25 10 5 activation energy i kcoi i m o l l fig. 5. frequency distribution of activation energy of polar and temperate arthropods. 0: temperate mites (young 1979); w : alpine temperate arthropods (conradi-larsen 1974; hbgvar & bstbye 1974; steigen 1976); h antarctic and sub-antarctic arthropods (young 1979; block 1981); 88 spitsbergen arthro pods (table 3 in present study). 240 t . aunaas, j . g. baust and k . e . zachariassen extremely high activation energy values (zacha riassen pers. comm.). these observations provide further support to the view that the activation energy reflects the predominant temperature con ditions under which a species lives. acknowledgements. this study was made possible by econ omic support from the norwegian research council for science and the humanities, the norwegian marshall fund. the norwegian polar research institute. and the department of zoology. university of trondheim. the authors express their gratitude to these institutions. we also thank professor arnol dus schytte blix. department of arctic biology. university of tromsa. who provided accommodation and laboratory facilities in adventdalen. and drs. erling sendstad. per sveum. and arne lauvaas for help with classifying part of the material. references block. w. 1981: respiration studies on some south georgian coleoptera. colloque sur les ecosysremes subanrarcriqrces. p a i m p o n f , c . h . f . r . a . no. 5 1 . 183-192. block, w . & young, s . r. 1978: metabolic adaptations of antarctic terrestrial micro-arthropods. comp. biochern. physiol. 6 1 a i 363-368. conradi-larsen. e. m. 1974: a constant pressure micro respirometer for measurement of 02-consumption in collem bola. nor. ent. tidsskr. 21. 187-189. duman. j . g. 1977: the role of macromolecular antifreeze in the darkling beetle, meracanrha contracta. 1. comp. phyjiol. 115. 279-286. duman, j. g . 1979: thermal hysteresis factors in over-wintering insects. j . inrecr physiol. 25. 805-810. engelmann. m. d. 1963: a constant pressure respirometer for small arthropods. e n . news 74. 181-187. grammeltvedt. r. & steen, j . b . 1978: fat deposition in spitsbergen ptarmigans. arctic 31, 496498. higvar. s . & bstbye, e . 1974: oxygen consumption, caloric values. water and ash content of some dominant terrestrial arthropods from alpine habitats at finse. south norway. n o r . ent. tidsskr. 21, 117-126. krog, j . o . , wika. m . , lund-larsen, t.. nordfjell, j . & myrnes. i. 1976: spitzbergen reindeer: morphology, fat storage and weight in the late winter season. nor. j . 2001. 2 4 . 407-417. ringberg. t . & reimers, e . 1982: an epic in high arctic survival. the svalbard reindeer. a c t a physiol. scand. steigen. a . l. 1976: energy metabolism in the wolf spider pardosa palurtris (l.) (araneae. lycosidae) from hardan gervidda. southern norway. nor. j . ent. 23, 51-60. s~imme, l. 1979: insektliv pb svalbard. fauna 32, 137-144. somme, l. & conradi-larsen, e . m. 1977: cold-hardiness of collembolans and oribatid mites from windswept mountain ridges. oikos 29, 118-126. young. s . r . 1979: respiratory metabolism of aiuskoretes antarcticus. j . insect physiol. 25. 361-369. zachariassen. k. e. 1977: ecophysiological studies on beetles from arid regions in east africa. n o r . j . ent. 24. 167-170. zachariassen. k. e. 1980: the role of polyols and nucleating agents i n cold-hardy beetles. j . comp. physiol. 140. 227 234. zachariassen. k. e . . baust. j . g. & lee, r . e . 1982: a method for quantitative determination of ice nucleating agents in insect hemolymph. crvobiology 19. 18@184. zachariassen. k . e. & husby. j . a . 1982a: antifreeze effect of thermal hysteresis agents protects highly supercooled insects. y a t u r e 298. 865-867. zachariassen. k. e . & husby. j . a . 1982b: stabilization of highly supercooled insects by thermal hysteresis antifreeze agents. abstract from symposium on invertebrate cold-har diness. oslo. august 1982. cryo-letters 3 , 316. composition and provenance of the lilljeborgfjellet conglomerate haakon vii land, spitsbergen tore gjelsvik gjelsvik, t . 1991: composition and provenance of the l.illjehorgfjellet conglomerate haakon v11 land, spitshergcn. polar resenrch 9(?). 141-154. the siktefjellet group of late silurian or early devonian age. consisting of the ldljehorgfjellet con glomerate and thc overlying siktefjellet sandstone, is generally accepted as thc oldest part of the old kcd sandstone in spitsbcrgcn. most of the ckrsts of the conglomerate arc only slightly roundcd a n d conaist oi htholopies typical for the underlying basement. a minoi component of quartz porphyry clast, is prescnt: these are well-rounded. indicating a longer transport. the provenance of thc quartz porphyry cl;i\ts is discussed in relation to the known outcrops of quartz porphyry in svalbard. one occurring in the ncigh bourhood of the conglomerate. thc other one5 far away. the quartz porphyry in close proximity i \ younger than the lilljchorgfjrllet conglomcratc and therefore no! a possible source rock. a closc petrographic and geochemical comparisoii with the quartz porphyries at three localitics in nordaustlandet (15g-200 kin in castcrly dircctioii and ot prohahle grenvillian a g c ) is presented showing many aimilaritics. hut enough differences t o qucstion their interrclationship. thc porphvrics of the hornsund area (300 kni in routhcil! direction and also of probable grenvillian age) are found to hc chemically and petrographically distinctly different from the lilljeborgfjellct clast porphyry. metai-hyolice rcported from the plaiicrficllii a n d hitr kerbreen groups in ny fricsland arc not comparahle with thc cliist porphyry. as n o unquestirinahlc w u r w rock among the quartz porphyries is known in outcrop. the possibility of a hidden or complctel! crodcd parent rock ia considered. tore glelsuik. norsk polnrimtinttt, p . o . box 158. n-1330 oslo lufthaon. norwuccy. -anah introduction bay conglomerate to the red and yellow marble during a sledge expedition in 190y, 0. holtedahl (1026) investigated the devonian red bay series around raudfjorden. t h e series which had been reported previously by nordenskiold (1892) is confined by north-south trending faults and con sists of a basal conglomerate and overlying sand stones of typical old r e d sandstone (ors) affinity. in rabotdalen, on the east side of the fjord, holtedahl noticed two kinds of con glomerate, o n e coloured red and yellow and dom inated by marble and dolomite clasts. the other more polymictic boulder breccia of grey colour. although the conglomerates were separated by a distinct fault, holtedahl considered them t o be only different facies of the basal devonian con glomerate. later named by friend (1961) the red bay conglomerate. g e e 8 moody-stuart (1966) conglomerate and the overlying red brown quartz chip conglomerate of earlier published studies. when investigating the lilljeborgfjellet con glomerate, the present author noted a striking difference between most of the clasts. which are only slightly rounded and consist of lithologies common in the neighbouring basement: a few are well-rounded and composed of quartz porphyry. the latter are unknown in the basement except for some occurrences in nordaustlandet and the hornsund area. these observations raise the question of a very long transport distance of the quartz porphyry clasts versus the possibility of hidden or eroded occurrences of quartz porphyry at a closer distance. extent and lithology found that the grey breccia, which they named the lilljeborgfjellet conglomerate. is the basal . unit of a conglomerate-sandstone succession except for some areas which are covered by gla resting unconformably on metamorphic rocks and ciers, the 150 t o 400 m thick lilljeborgfjellet con discordantly overlain by the r e d bay conglomglomerate extends as a continuous unit from the erate. they proposed the name siktefjellet g r o u p rabotdalen pass east of raudfjorden to the for this succession, restricting the use of the r e d siktefjellet mountain o n the northern share of 142 t . gjelsvik fig. i . geological sketch map. extracted from gee & moody-stuart (1966. fig. 1). locations of nordaustlandet quartz porphyries: b = botniahalvoy. s = sabinebukta. pol = prins oscars land (rijpdalen). location north of hornsund: v = vimsodden. h'f = ny fricsland composition and provenance of the lilljeborgfjellet conglomerate 143 liefdefjorden (fig. l), a distance of 14 km. it generally dips 3&50”wsw. in puddingen, to the north of rabotdalen, an isolated outlier of “a red quartz conglomerate” was found by holtedahl (1926, p. 11) who considered that it belonged t o the red bay conglomerate series. however, gee & moody-stuart (1966. p. 62) included it in the siktefjellet group. this author has found two additional, isolated occurrences of the same con glomerate on either side of the hannabreen gla cier tongue in liefdefjorden. gee & moody stuart (1966) also considered the possibility that the marble conglomerate at the promontory of konglomeratodden on the western side of raudfjorden might be a separate unit of the siktefjellet group, without giving conclusive evi dence. at its northern end i n rabotdalen (fig. 1). the lilljeborgfjellet conglomerate tapers out with a basal breccia resting on an irregular basement of schists and gneisses. when visible, the contact is mostly sharp, in part tectonically disturbed by steeply west-dipping shear planes. in other places, the immediately underlying basement is coloured red by a network of small, hematite-bearing veins down to a depth of 20-30m below the uncon formity. also, the basal part of the conglomerate comprises numerous clasts of gneiss containing the same hematite vein system. in one place hol tedahl (1926. p. 12) also noted a transitional layer of huge, angular pieces of crystalline rocks between the conglomerate and the basement rocks. the breccia in rabotdalen consists of very coarse (up to 1 m), angular clasts of gneiss, marble, and metabasites (fig. 2), many of which are garnet-bearing and of medium t o high meta morphic grade. similar lithologies occur in small areas of the adjacent crystalline rocks (gee 1966, chap. 6). both stratigraphically upwards and lat erally southwards the conglomerate clasts gen erally become more rounded, the proportion of quartzite increases, and especially in the tran sition zone to the overlying siktefjellet sandstone the clasts diminish to form a pebble conglomerate interbedded with arkosic sandstone. in the inter mediate and lower levels the clasts are still mostly massive, and particularly in the basal part angular clasts of crystalline schists or gneisses are ubiqui tous. clasts of coarse-grained marble are also common, but dolomite marble, which is so fre quent i n the red bay conglomerate, is very rare. less common. but nearly always present, are the well-rounded clasts of quartz porphyry. these are much better rounded than the clasts of other lithologies (fig. 3). in most cases they make up only 1% or less of the clasts. in one place, however, as much as 5 1 0 % has been observed. the size ranges from a few cm to 1.5 m, but most clasts are small. the subordinate matrix of the lilljeborgfjellet conglomerate consists mostly of small pieces of the same rock types as in the larger clasts, perhaps with a greater proportion of mica rich schists and gneisses. unfortunately. this study lacked the necessary logistic support for a detailed sedimentologic fig. 2 . angular clast of augcn gneiss (below center) in massive lilljeborgfjellet conglomerate, rabotdalen. 144 t . gjelsuik fig. 3. wcll-rounded clnst of quartz porphyry. 1111 long, in lilljehorgfjellet conglomerate. eastern hordcr ot the snout of hannahrecn. investigation of the lilljeborgfjellet conglom erate trcvii rabotclalen all the way to siktefjellet. most o f the observations ;ire from exposures in the vicinity o f raudfjorden in the north and lief defjorden in the south. t h e conglomerate is t o a great extent c w e r e d bx debris or snow: the best exposures are either inaccessible o r too hazardous for field observations. t h w . i t w i i s not possible to investigate n h e t h e r there are any internal stratigraphic relation\hips defined by the quartz porphyry clasts. n o r was i t possible to measure an! lateral variation in their frequency distri but 1011 . the lithology and angular to subrounded shape of the clasts. except for the small number con sisting of quartz porphyry and perhaps for the most rounded quartzites. indicate a short trans port of the components of the lilljeborgfjellet conglomerate. all lithologies. again with the exception of the quartz porphyry, are comparable with those of the underlying o r adjacent meta morphic rocks (holtedahl 1926; harland 1961; gee & moody-stuart 1y66). it should be especially noted that exposures of garnet-bearing. medium to high-grade metabasites in spitsbergen are restricted to the adjacent richarddalen corn plex (see map. tig. 3 in peucat et al. 1989). o n the other hand. the quartz porphyry clasts present an enigma. at least a contradiction. their uell rounded shape. despite the tough and hard com position. testifies of a longer transport than for the other clasts. however. quartz porphyry has nowhere been observed in the hecla hoek suc cessions of northwestern spitsbergen. exposures of quartz porphyries in svalbard quartz porphyry outcrops have been reported from five areas in svalbard. t h e o n e nearest to the lilljeborgfjellet conglomerate is located on the frxnkelryggen ridge in raudfjorden. o n l y about 2-3 km southwest of lilljeborgfjellet. three other outcrops are located 150-200 k m to the east. on the island of nordaustlandet (fig. 1). quartz porphyry has also recently been found on t h e western coast of spitsbergen, a little to the north of hornsund. fr:rtrrrkelrj,ggeti u r t x in the frmkelryggen a r e a . two beds of "welded t u f f " . each 4 ni thick. are interbedded in the f r z n kelryggen sandstone which is situated in the middle of the red bay g r o u p (murasov et 31. 1983). besides phenocrysts of quartz and feldspar i n n microfelsitic groundmass. the welded tuff contains about 30% clastic fragments and might rather be called a tuffite. in this way i t differs from the quartz porphyry clasts and the nordaustlandet quartz porphyries, none of which contain extraneous clastic components. plagioclase phenocrysts make up 3 5 y of the rock, ortho clase 1-29>, the sizes are (1.2-0.4 nim and 0. i 0 . 2 mm respectively. orthoclase phenocrysts are completely altered t o clay minerals. the groundmass is excessively replaced by carbonate. mica and chlorite. t h e rock is mottled with a carbonate mineral. a phase which also occurs in composition and provenance of the lilljeborgfjellet conglomerate 145 tuble 1. chemical composition (anhydrous) of quartz porphyry from fraenkelryggen and from the vimsodden conglomerate, and of posttectonic granite from northwestern spitsbergen. n o sioz ti02 a1203 fe,03 fco mno mgo cao nazo kzo p,o, total 1 71.15 0.18 17.27 1.32 0.79 0.11 1.51 1.85 1.60 4.06 0.13 99.97 2 76.69 0.22 14.00 1.16 0.71 0.06 1.20 1.93 1.45 2.50 0.13 100.00 3 73.91 0.20 15.64 1.24 0.75 0.09 1.36 1.89 1.53 3.28 0.13 99.99 4 70.01 0.22 12.73 4.19 0.65 0.02 0.60 1.59 0.23 9.59 0.11 99.99 5 62.22 0.18 14.67 2.72 1.60 0.41 1.31 5.45 0.30 10.97 0.16 100.00 6 66.12 0.20 13.70 3.46 1.13 0.22 0.96 3.52 0.27 10.28 0.14 100.00 7 70.94 0.31 15.07 0.49 2.06 0.04 0.59 1.87 3.15 4.44 0.07 99 83 no. 1 welded tuff, fraenkelryggen, upper layer. no. 2 welded tuff, fraenkelryggen. lower layer. no. 3 average of 1 and 2 no. 4 porphyric clast, vimsodden conglomerate, hornsund. no. 5 aphanitic clast, vimsodden conglomerate, hornsund. no. 6 average of 4 and 5. no. 7 average of 8 samples of granite dikes, northwestern spitsbergen (hjellc in hjelle & ohta 1974, table 3) numerous microfissures. the upper bed has a 10 cm thick sole with quartz and orthoclase phenocrysts up to 5 m m in length. two major element chemical analyses, one from each bed (murasov et al. 1983, p. 98), are recalculated to 100% (anhydrous) and presented as no. 1 and 2 i n table 1. hornsund area smulikowski (1968, pp. 108-111) reported the presence of slightly metamorphosed rhyolite clasts in a proterozoic, polymict conglomerate at vimsodden (v in fig. 1). according to his description, the clasts only contain phenocrysts of potash feldspar, maximum 2 x 5 mm in size, imbedded in an aphanitic, dark grey matrix and usually exhibiting preferred orientation con cordant with the elongation of the pebbles. the matrix consists mainly of quartz and microcline with minor amounts of secondary biotite, sericite and chlorite. some of the phenocrysts are crushed and deformed, resulting in the crystallization of quartz, biotite and carbonate in internal fissures and along the grain boundaries. the chemical compositions of one porphyric and one aphanitic rhyolite pebble (smulikowski 1968, table 2), recalculated to an anhydrous composition, are reproduced in table 1 (nos. 4 and 5 ) . the rhyolite clasts described by smulikowski do not contain phenocrysts of quartz. however, according to y . ohta (pers. comm.) both rhyolite and quartz porphyry lenses have been found in the adjacent skslfjell amphibolite complex (birkenmajer & narebski 1960, fig. 1) which is probably of gren villian age (peucat pers. comm. 1991). like the rhyolite pebbles of the vimsodden conglomerate, the chemical composition of these acid vulcanites is characterized by extremely high potash and very low sodium contents. nordaustlandet areas quartz porphyries occurring on nordaustlandet (fig. 1) appear in the form of massive bodies, plugs and dikes in botniahalvoya (b) and sab inebukta (s), whereas in prins oscars land (pol) they are strongly foliated and appear as folded sheets. the massive rocks are only slightly altered, mainly by sericitization of the plagioclase phenocrysts and the groundmass, whereas in the pol sheets intense sericitization and carbonate replacement have often led to a complete destruc tion of the feldspar phenocrysts (flood et al. 1969; ohta 1984). however, the metamorphic processes have not obliterated the typical por phyric texture of the rocks nor the characteristic late magmatic corrosion features of the quartz phenocrysts. the botniahalvoya quartz porphyry has been dated by the rb/sr whole rock isochron method t o 766 ma by gorochov et al. (1977), and has been recalculated by the same authors to a model age of 970 ma. the quartz porphyry clasts in the lilljeborgfjellet conglomerate resemble the nordaustlandet rocks, both in the frequency and in the composition of the various phenocrysts (table 2 ) . the feldspar phenocrysts have not been separated in table 2 due to the complex 146 t . gjelsvik tubk z proportions o f matrix and phenocrystc. location n matrix phenocrysts q u a r t z feldspar ~ haakon v i i land (lc' cla\ta) 13 55-81 3-26 12-25 botniahalvo)a ( b ) 6 5 s l . i . h i 3 11-25 sahinobukts ( s ) 2. hj-67 1&13 zk-2.1 prim o5cars land ( p o l ) 7 xo-89 h ( & i i total nordaustlandcr i 1 59-89 3-13 g 2 5 the pcrccntagc\ i l o m xordaustlandet are calculatcd from ohta ( i y x 4 . tahle 2 ~ ) . intergrowth of the alkali feldspars in the clasts. to be described below. t h e apparent lithologic similarity between quartz porphyry clasts of the lilljeborgfjellet conglomerate and the nord austlandet quartz porphyries prompted a detailed petrographic and geochemical study of the former as a basis for comparison with the relevant data of the latter (flood e t al. 1969: o h t a 1984). petrography in both the lilljeborgfjellet and the nordaustlan det suites. the size of the quartz phenocrysts is mostly between 2 and 5 mm: the feldspars a r e a little larger. however. in o n e of the clast samples the feldspar phenocrysts measure up to 2.5 cm. in the massive quartz porphyries of nord austlandet the alkali feldspar phenocrysts are composed of homogeneous orthoclase or finely lamellar perthite (fig. 4). in the lilljeborgfjellet conglomerate (lc) porphyry clasts, the alkali feldspar phenocrysts display a coarse, patchy intergrowth of potash feldspar and sodic plagio clase (fig. 5 ) . t h e uniform extinction of t h e pot ash feldspar domains in the plagioclase host crystal indicates that t h e pattern is formed by exsolution rather than by replacement. some times the potash feldspar forms an outer rim or follows the cleavage directions in the host crystal. in both cases the plagioclase phenocrysts a r e com posed of oligoclase which in nordaustlandet is evenly and densely clouded by sericite. in the lc porphyry clasts they a r e replaced by more coarse grained sericite in irregular patches, along veins or in the marginal zones of the grains. t h e matrix of the nordaustlandet quartz por phyries is microcrystalline and mostly granular, evidently d u e t o recrystallization. equigranular quartz and feldspar crystals. usually less than 0.02 m m , mixed with scaly sericite. are the main constituents. in a few cases a primary texture of platy. radial feldspar in a spherulitic pattern is fig. 4. quartz porphyry. botniahalv~ya, nordaustlandet. fig. 5 . sericitized, foliated quartz porphyry, pol (rijpdalen). phenocrysts: quartz. plagioclase (rhomboidal), perthite (lower phenocrysts: quartz. (left center, diamond shaped), sericitized left, extinct). 32x potassium feldspar (right center). 1 3 x . composition and provenance of the lilljeborgfjellet conglomerate 147 fig. 6. rounded phenocryst with intergrowth of plagioclase (white) and potassium feldspar (dark) in clast porphyry from lilljeborgfjellet. note jagged border of the phenocryst d u e to recrystallization of the groundmass. 13x. observed, indicating devitrification. in the pol rocks. the sericite is sometimes slightly coarser and concentrated in densely foliated bands (fig. 6). the contact of the phenocrysts appears mostly sharp and smooth, although under high mag nification it can be seen that the sericite crystals intersect the margins. stronger recrystallization of quartz, chlorite, muscovite, and sometimes calcite is seen in strain shadows of the pheno crysts. in the l c porphyry clasts recrystallization of the matrix is more advanced than in the nord austlandet porphyries (except perhaps, for some in pol). a granular texture dominates. the grain size of the groundmass is usually in the range of 0.04-0.1 mm, i.e. twice as coarse. t h e matrix minerals are the same as in nordaustlandet: quartz, feldspar and sericite. potash feldspar f g . 7. glomeroporphyric feldspar with opaque seam along the margin. clast porphyry, lill~eborgfjellet. 1 3 ~ . seems t o b e the most abundant feldspar, making up perhaps 30% of the matrix. t h e phenocrysts are strongly indented by the matrix minerals, including chlorite and sometimes calcite. iron ore is present in clusters of large, often idiomorphic crystals together with chlorite and calcite in cross cutting veins and as tiny crystals in the matrix. in one of the clast samples. some plagioclase phenocrysts are encrusted by an opaque rim indi cating quick, subaerial cooling. they also have a peculiar glomerophyric texture not observed in the other samples (fig. 7). a t the same time the matrix often shows a spherulitic texture. t h e source rock of this clast would be of pyroclastic origin. both in the porphyry clasts and in the nordaustlandet porphyries, clusters of coarse crystals of quartz, calcite. muscovite, sphene. and iron ore are seen. perhaps representing more o r less recrystallized amygdales. chlorite, muscovite and iron o r e also occur, derived through replace ment of larger biotite crystals. to sum up the petrographic evidence, the quartz porphyry of the l c clasts porphyry is in most respects similar to those in nordaustlandet. the main difference is found in the structure of the alkali phenocrysts and the generally more advanced recrystallization of the former. t h e two associations both comprise subvolcanic and pyro clastic units which have been metamorphosed in greenschist facies. geochemistry the major element composition of the l c por phyry clasts is given in table 3, which also pro vides the average ( a v . ) compositions of the various oxides. according to the t a s classifi cation all the analysed rocks a r e high-k rhyolite (le maitre 1989, figs. b14 and 15), although a few a r e close to the borderlines of dacite and trachyte, respectively. t h e average compositions of the nordaustlandet porphyries a r e included in the table for comparison. there is good agree ment for most of the elements, the main dif ferences being lower al and p , much higher fe3+, and a little higher c a in the l c clast porphyry. the sioz content of the clast porphyry agrees with the porphyry of b o t n i a h a l v ~ y a . however, the latter has an even spread of sioz between 70 and 7 5 % , whereas the clast porphyry has two distinct concentrations of 70 and 74%. k is nearly the same as in the b o t n i a h a l v ~ y a area, but dis 148 t . gjelsuik table .t, major clement composition (anh!drous bascl of quartz porphvq ciast, in li~ljehorgfjellet conglomerate. tio: aiio. fc:ol feo m n o mgo cao na,o k 2 0 p 2 0 1 total 78-gj. i i 1c 78-gj. i 5 1 a 78-gi i 5 1 8 7x-gj.i5?a 78-gi 1578 78-gj 157c 78-gi l5y.a 78-gj. 15qb 78-gj. 15ye 78-gj.177d 7x-gj.182 78-gj. i y 1 u av. (i31 78-gi. 1 5 y ( ~ 73.7s 73.6’) 73.24 70.22 70.115 70.19 711.38 74.0’) 71.53 74. i i 73.51 73.41 71 12 72.3.7 (1.37 u.48 0.13 (1.67 (1.63 0 78 0 72 0 32 0.5x 0 4 1 0.43 0.66 0 31 (1.57 a \ . b ( 7 ) 72.77 0.3(1 a\.. s(3) 73.82 0 . 1 9 a \ . pol(%) 75.13 0 3 2 i2 83 12.x3 12.87 13.26 11.83 13 17 12.93 13.10 11.84 12.7x 12.89 1 l . 2 0 12.74 11.81 2.14 0.46 1.92 1.13 1.57 1 . 1 1 3.61 1.31 4.59 1.15 2.16 3 . m 4.1 1 1.08 0.55 1 3 4 3.73 0.78 0 . 4 3 2.05 -._ 7 i 6 0.28 1.64 1.75 1.81 0 47 2.37 1.66 15.06 0.57 1.44 14.81 0.37 1 5 1 14.54 o.no 1.6s 11.01 0 112 o.i)2 0.03 0.03 0.07 0.02 0 (13 0.02 0.03 u.02 0.m 1).03 i) 03 i1 02 i).o? u.03 ~ 0.62 0.72 1.09 1.35 0.44 1.37 1.37 1.73 0.63 0.50 0.27 1.60 0 . 3 3 n.92 ~ 0 . 5 1 u 79 11.81 1.67 0.94 0.31 1.49 1.50 1.36 1.69 2 67 0.95 0 91 1.70 5.77 1 .63 0.78 2.16 6 . 5 2 1.65 7.65 3.40 4.50 3.49 4.11 2.80 4.73 1.96 5.43 3.30 5.25 3.23 4.84 2.86 5.78 2 . 8 4 5.82 3.32 5.06 3.07 4.04 1.53 6.39 2.75 5.31 0.04 0.06 0.06 0.13 0.14 0. i5 0.14 0.04 0.12 0.05 0.06 0.12 0.04 0.09 100.00 y9.yy 1ou.00 yy.ys 99.99 100.01 99.97 y9.97 yy.99 99.99 yy.yy 99.90 1 ou 011 1.09 7 . x 1 5.16 0.23 0.78 3.14 3.y4 0.19 1.06 1.49 3.91 0.11 sdmple n o 78-gi. 1 i ic is collected near the hogeloftet ridge north of liefdcfjorden. the other samples arc from the area hetwccn kahotdalen and lilljchorgfjcllct on the eastcrn 51de of kaudfjordcn. tinctly higher than in the two other areas in nor daustlandet. in figs. %11 t h e distribution of the elements of the lc clast porphyry is shown by crosses in the various oxide variation diagrams given by o h t a (1984. pp. 85-88, 90) for the nor daustlandet rocks. fig. 8 a shows that the total alkali content of t h e l c clast porphyry is in the same range, or slightly higher range, as that of botniahalvcbya. in the alkali variation diagrams (fig. 9c) it is seen that especially the k ? o content of some samples is higher. although most of the samples are within the same range as the bot n i a h a l v ~ y a rocks. since the l c clast porphyry has been subjected to extensive sericitization of the matrix as well as the feldspar phenocrysts, it is conceivable that some k has been introduced. however, the al diagram (fig. 9 c ) shows that the a1203 content of the l c porphyry clasts is consistently lower than the content of the clasts of nordaustlandet. moreover. the a1 content of the former lies in the range of representative rhyolites of the andesite-rhyolite family (car michael et al. 1974. table 2-2). these relation ships suggest that the source rock of the clast porphvry initially has a high amount of potash feldspar, rather than being subjected t o potash metasomatism at a later stage. t h e relevant dia grams in fig. 9c demonstrate that the trends of feo, mgo and c a o in t h e clast porphyry are the same as in the nordaustlandet rocks. however, both fe and c a have been mobilized and perhaps introduced during the recrystallization of the clast porphyry. as shown by the vein-like or cleavage related distribution of iron oxides in some samples, and by the numerous cross-cutting cal cite veins. because of the latter, o n e very high ca figure was discarded from the diagram. according to the data for a1 and the alkalis given by carmichael e t al. (1974). mueller & saxena (1977). and wilson (1989). the l c clast porphyry compares better with the acid derivates of continental tholeiitic flood basalts and other continental rhyolites than with oceanic and vol canic arc rhyolites. accordingly, the clast por phyry is most probably derived from a continental source. trace element data o n the l c porphyry clasts are given in table 4. o h t a (1984, table 6) provided trace element data only for sr, ni, co and c r for the nordaustlandet quartz porphyries, classified as h-k and m-k c a rhyolites. compared with his figures, sr in the clast porphyry is similar t o the m-k c a rhyolite. but much higher than the h-k rhyolite. ni and c r a r e much lower than i n both kinds of t h e nordaustlandet rhyolites; co is also lower. t h e content of pios is distinctly lower in the clast porphyry (fig. 11a), and .the ni/cr proportions are also different (fig. 11b). trace composition and provenance of the lilljeborgfjellet conglomerate 149 a j o t i i + i + a _ _ + 0 0 - 0 i i 1 i i _-c_-- 0 r h yo1 i le dacire *-i_* i i ' j 65 70 7 5 sio, w t % [ h y d r o u s ) b feo' c a2 * / \ 4 ,z / / / / / f i i i _ or + + + na,o + k,o ab fig. 8. a . alkali-sioz diagram (hydrous). b. afm diagram. c. normative qz-ab-or diagram. symbols: open circles = botniahalveya; solid squares = sabinebukta; solid circles = prim oscars land; crosses = lilljeborgfjellet conglomerate clast porphyry. reference for dividing lines in ohta (1984, fig. 9). 80 0 5 7 0 . b a . 0 + + + . / : ' + + 0 . ,' +.+ / f *+ 5 2 3 u 1 + _ , c 3 i l 1 ' + .+ a + + a ' ++ ++* + .'ct * * + -+. 0 c' 3 z 1 . 1 2 3 4 5 6 1 feo' mgg fig. y. a si02-fco'mg0 d i a g r a m . b. fco-fco \1go diagram. c-. tlarker \ a r i a t i o n d i a s r a m s . symbol5 as for fig. 8 refercncc f o r dividing lines i n o h t a (198-1. fig. 1 0 ) + + + i$+ a + + m + ' + +*+* <> r * + element data of rhyolites elsewhere a r e scarce. even rarer for quartz porphyries. according to tables in the textbooks of carmichael et al. (1971) and wilson (1989). c r . ni, ba, r b and zr in the lc clast porphyry compare well with those of the rhyolites in continental. tholeiitic flood basalt provinces. but sr is somewhat lower, as a r e p 2 0 5 and tio?. discussion a n d conclusion the chemical and mineral compositions of the welded tuffs in the frznkelryggen sandstone for mation differ considerably from that of the lc quartz porphyry clasts. according to the description by murajov et al. (1983). the alter ation of the tuffs also seems to be greater. i f they were to be the source rocks. it would also imply an inversion of the succession since the siktefjellet group underlies the r e d bay g r o u p . as there is c "[ <> + 1 : + a + . + i r 5 t 70 sio, 75 wi 46 (anhydrous) 80 composition and provenance of the lilljeborgfjellet conglomerate 151 t d e 4 tracc clrments of quartz porphjry clasts. sarnplc no. ba co cr cu nh ni r h sr y zn zr 78-gj.lllc 985 29 16 17 55 1.1 274 39 103 24 418 78-gj.151a 1066 41 l 7 60 6.9 122 72 111 24 so8 78-gj. 157a 825 33 14 15.6 53 10.1 107 26 127 48 636 78-gj.159a 695 37 20 7.1 49 5.7 125 21 111 30 628 78-gi. 159b 781 49 27 22.4 45 5 . 1 151 51 86 30 341 78-gj.159e 1124 29 12 1.6 51 78-gj.177d 1992 40 0.7 47 4.1 143 84 99 20 421 78-gj.182 690 36 7 1.5 55 3.4 101 84 102 48 507 45 0.9 187 127 y i 12 34y 78-gj.191d 776 26 60 averagc(x) 1331 40 19 6 53 4 153 h6 109 4 1 s1)h 7 7 8 4 ; . 151b 883 40 25 3.5 58 1.9 226 37 115 38 468 78-gj.1579 1192 62 7 y 58 8.6 125 100 132 26 676 78-gj.157c 1124 36 18 5 . 5 57 2.6 99 93 128 116 684 78-gj.lsyc 1274 57 13 4.3 48 4.8 154 66 104 67 548 183 61 i09 4 1 40.5 o n . i0 17 3 30 for sample locations see table 3 . no indication of an inversion here, this alternative can be ruled out with some confidence. bulk chemistry and petrography of the l c clast porphyry are in many respects similar to that of nordaustlandet. t h e main petrographic dif ference is the structure of the alkali phenocrysts and, at least in relation to the quartz porphyries of b and s , a more advanced recrystallization of the l c porphyry clasts. both associations com prise subvolcanic and pyroclastic units which have been subjected to metamorphism in greenschist facies. in most respects there is also good cor relation between t h e chemical composition of the quartz porphyry clasts and that of the nord austlandet quartz porphyries, especially those of botniahalvoya. but there a r e deviations par ticularly in the amounts of al, c r and ni, which speaks against the possibility of the nordaust landet quartz porphyries being t h e source rocks of the l c quartz porphyry clasts. this alternative also raises other objections. not only is the trans port distance from nordaustlandet to haakon vii land very long, but the direction is transverse to the general structural trend of the basement. which would probably create topographic barriers for river transport. considering the large size of some of the clasts, it is especially difficult t o reconcile the idea of such a long transport fig. 10. alkalis vs. 100 k 2 0 / n a 2 0 + k 2 0 diagram. symbols as for fig. 8. reference for dividing lines in ohta (1984, fig. 12). 0 0 a a i 10 20 30 40 50 60 70 80 90 100 100 k,o na.0 + k,o 152 t. gjelsvik a a a a acid andesite i dacite rhyolite b a s l c andesite 0 . a t aa a a 3 ,..o . o&oc 0 0 0 0 i . @ . . . . 0 ++ a + t * 2 +a 50 ’ 0,3 ’ 0.2 . 0.1 k+.+4 , . . . . . . . . . . . . . . , 1 00 150 200 250 cr (ppm) fig. / i . a pio,-s~o, diagram. symbols: 9 = hasic dike rocks. nordaustlandel; open circles = porphyrite and andcsitc, nordaustlandet: solid circle\ = metadiabase. nordaustlandel: solid triangles = quartz porphyries, nordaustlandet; crosses = lc cla\t porphyry. dividing lines from ohta (1yx4. fig. 1 l a ) . b . ni-cr diagram. symbols: open circles with horizontal lines = high k:o calc alkaline rocks open trimgle = medium k:o tholeiites: solid triangles = high k>o tholciitcs: crosses = lc clast porphyry. refercncc for hrokcn curve. ohta (19xj. fig. 1 l c ) distance. on the other hand. the rounding of the clasts suggests that they are not derived from the adjacent basement rocks. the quartz porphyries in the hornsund area are also unlikely to be the source of the lc clasts, since the chemistry as well as the petrology of the two types are v e r y different. t h e distance between them. 3uu k m , is also very long, but it might have been less prior to possible strike slip movement along the western spitsbergen fold belt direction. also from nv friesland ( n f on fig. 1). the northeastern peninsula of spitsbergen. rocks thought to be derived from acid volcanics have been reported (gayer & wallis 1966; wallis 1969). they occur both in the basal part of the planetfjella g r o u p and in the upper formations of the underlying ilarkerbreen group: they mostly comprise massive. feldspar-rich beds, now present as augen-gneisses. they are considered to be reworked. acid pyroclastics (gayer & wallis 1966). some smaller beds consisting of crenulated schists with “megacrysts“ of feldspar ( u p to 5 mm in length). set in a fine-grained groundmass. are called meta-acid-tuffs. they have not been reported to contain relics of quartz phenocrysts. n o chemical data on these rocks has been published, and their origin is uncertain (wallis 1969). recent zircon u/pb dating ( g e e 1991, unpubl. data from peucat & tebenkov 1990; o h t a in press) has shown that the harkerbreen g r o u p belongs t o the sveco-karelian period, whereas the planetfjella g r o u p may b e of grenvillian age. the rocks have been subjected t o orogenic deformation and recrystallization in amphibolite facies, and the feldspar “megacrysts” occurring in both groups could b e a product of caledonian or older events. whatever their origin, they are not similar t o t h e lc quartz porphyry. thus, none of the known outcrops of quartz porphyry in svalbard satisfy the petrological and chemical criteria for the source rock. most of the clasts in the lc can readily be matched with lithologies in the adjacent basement. o t h e r alternatives must therefore be considered, such as quartz porphyry bodies which have been com pletely eroded. t h e adjacent area of northwestern spitsbergen consists of amphibolite facies gneisses, migmatites and granite. a t originally higher stratigraphic levels, extrusive or sub volcanic rhyolite might have occurred. as referred t o above, “welded tuff” of quartz por composition and provenance of the lilljeborgfjellet conglomerate 153 phyric composition is interbedded in the fraen kelryggen formation of the red bay group which was deposited in the early gedinnian (blieck et al. 1987) at about 400410ma. however, the source rock in question would have to have been formed earlier. acid igneous activity (including the hornemantoppen granite) in northwestern spitsbergen started somewhat earlier, a related vulcanite might have provided a source. however, the interrelationship of the deep-seated granites of north-western spitsbergen and the welded quartz porphyric tuff in frankelryggen is still an open question. although the corre spondence of most elements in the two rock types is good (table l), it is less so for the alkalis and mg. the correspondence is somewhat better for these critical elements when comparing the post tectonic granites and porphyry of the lc clasts, but the a1203 contents of the former are more than 2% higher (table 1). in 21 samples of syn tectonic granites (> 68% s o z ) from the smeer enburgfjorden area, the average al2o3 value is more than 3% higher (calculated from ohta, table 5 , pp. 94-95 in hjelle & ohta 1974). in any case, because of the deep erosion, the tectonic setting, and the high metamorphic grade of the rocks to the north of kongsfjorden, a possible source rock on the western side of the devonian graben could only be expected south of kongsfjorden. despite high mapping activity in recent years on the western coast of spits bergen, no quartz porphyry outcrop has been reported north of bellsund. the same is the case for the anticlinal hecla hoek horst in the raudfjord devonian graben. other possible source rocks could be hidden under the sediments of the devonian graben, under large ice caps, or under the sea off the northern coast of spitsbergen. so far, no quartz porphyry pebbles have been reported from the shelf, but very little sampling has been done. the northern shelf is perhaps not a probable source area, since it would imply a transport direction in devonian time from north to south, opposite or transverse to what is believed by orvin (1940, p. 15) and friend & moody-stuart (1972, p. 17). the conclusions of their studies, however, are based on sedimentological investigations of the red bay/wood bay groups, and the pale ogeographical situation during deposition of the siktefjellet group might have been different. the seemingly increased degree of rounding south wards of most clast lithologies in the latter indi cates a source area to the north of the present location. this does not apply for the quartz por phyry clasts, however. which are equally rounded everywhere. it may be concluded that the present infor mation is insufficient to give a definite answer to the question of the provenance of the quartz porphyry clasts. isotope dating of zircons from these clasts may provide a useful constraint on the potential alternatives. acknowledgemenrs. the chemlcal analyses have been carried out by s . miyashita, department of geology, faculty of science. niigata university. japan. using x ray fluorescence methods. y . ohta and d . g . gee have read the manuscript and provided valuable guidance. which does not relieve the author of full responsibility for the text. references birkenmajer. k. & narcbski, w. 1960: precambrian amphibo lite complex and granitization phenomena in wcdel-jarlsberg land, vestspitsbcrgen: stitdin geol. p o l . iv, 37-82, blieck. a , . goujet, d . & janvier. p. h. 1987: the vertebratc stratigraphy of the lower devonian (red bay group and wood bay formation) of spitsbergen: m o d f r n geologv vol. 11, 197-217. carmichael. i . s . e.. turner, f. j . & verhoogcn. j. 1974: igneous perrologv. mcgraw-hill. flood, b.. gee. d . g . , hjelle a.. siggerud, t . & winsne,. t . s. 1969: thc geology of nordaustlandet, northern and central parts: norsk polarinst. skr. 146. 141 pp. friend, p. f. 1961: the devonian stratigraphy of north and central vestspitsbergen: proc. y o r k s . geol. soc. 33. 77-1 16. friend. p. f. & moody-stuart, m. 1972: sedimentation of the wood bay formation (devonian) of spitsbergen: norsk polarinst. skr. 157. 77 pp. gayer, r. a. & wallis, r . h . 1966: the petrology of the harkerbreen group of the lower hecla hoek of ny friesland and olav v land, spitsbergen: norsk polarinst. s k r . 1.10. 32 pp . gee, d. g . 1966: the structural geology of the biskayerhoekcn peninsula, north spitsbergen. ph.d. thesis, university of cambridge (unpubl.). gee, d. g . 1991: caledonian terranes on svalbard. new evidence of basement in ny friesland. abstract: geonyrr drgang 18 (1191). p. 24. gee, d . g. & moody-stuart, m . 1966: the base of the old red sandstone on central north haakon v11 land, vest spitsbergen. n o r s k polarinst. a r b o k 1964, 5 7 4 8 . gorochov, j . m . . kra'sil'stikov, a . a . . melnikov. n. n. & varsavskaya. e . s. 1977: rb/sr age of quartz porphyries of the kapp hanstecn series. pp. 51-61 in p r o b l e m y geo chronologii i geochtmii isotopou. nauka. leningrad (in russian). harland, w. b. 1961: an outline structural history of spits bergen. pp. 68-132 in raach. g . 0. (ed.): g e o l o g y of the arctic. univ. of toronto press. hjelle, a . & ohta. y . 1974: contribution to the geology of north western spitsbergen: n o r s k polarinst. skr. 158, 7-37. 154 t . gjelsvik holtedahl. 0. 1926. soteh t i n the gcolog! of north-ucstern spitshergcn: s k r . s i w l h . u k idrocw. n r . 8. 2 8 pp. lc m;iitrc. ed. ly8y: .4 c.lrirsificcrrron of lgnuoiis r o d s ( i d glo.\ror! of t r r t m black\\cll scientific puhlications. muellcr. r f 6: sa\cn;i. s k . 1y77 geoclretnicol perrulugr springer-verlag. murasov. l . g . . pfelina. t . m. & semevskij. d. v . 1983: n e w data on evidence of volcanism in lower devonlan and upper triassic formations of vestspitsbergen: geology of spilsbergen. collection of scientific p a p e r s , 96-101. sevmor geologija leningrad (translated 1984). nordensttold. (i i x v ? . rcdogjor fdr dcn svcnaha cxpe j i t i ~ e n t i 1 spet5hcrgen lsy(l; biliurig kring. so ver. . a k u f . hdi 17/.1/ i y n : gcochcnii\!r! of thc late proterozoic kapp tian\teen i g n c i w rocks o l n o r d a u d a n d e t . svalhard. iyxj: polirr keworch 3 t i . l , 6y-02 ohta. y . in press: recent understanding of the svalbard base ohta. y ment. in the light of new radiometric age determinations. norsk g e o l o g i s k tidsskrifr. orvin. a . k . 1940: outline of the geological history of spits bcrgen: n o r s k polurinsr. skr. 78. 57 pp. peucat. j . j . . o h t a . y . . gee. d . g . di bcrnard-griftithb. j . i y x y . u-ph. sr and nd cvidencc of grcnvillian and latest proterozoic tectonotherrnal activity in spitdxrgen calc donidel. arctic ocean. lirlio~ 2 2 . 175-285. srnulikowski. w . 1yh8: some petrological and structural ohser \ations in the hecla heel, succcsticn hetwccn wer enskioldhrccn and torellbreen. vest qitshergen: s r u d i c r geologicrr polotricci. vol. x . y i . 97-1.51 h ’ a i l i 5 . r. h . l y 6 y : t h e planetfjclla group of the lower hrcla hock of n y fricsland. spitshergcn: norvk pol(irrfrst arbok 1967. 7y-lox. wilson. m. 10x9: igneous petrogenesis a global tecronic npproacli. unwin hyman. photosynthesis, excretion, and growth rates of phaeocystis colonies and solitary cells peter g . verity, t h e o d o r e j . smayda and egll sakshaug verity, p. g., smayda. t. j . & sakshaug. e . 1991: photosynthesis, excretion, and growth rates of phaeocysfis colonies and solitary cells. pp. 117-128 i n sakshaug. e.. hopkins, c. c. e. & britsland. n. a. (eds.): proceedings of the pro mare symposium on polar marine ecology. trondhcim, 12-16 may 1990. polar research io(1). unialgal cultures of the prymnesiophyte. phaeocystis cf. pouchefii, were isolated from norwegian and united states coastal waters. manipulation of the nutrient medium resulted in populations overwhelmingly dominated by either colonies or solitary cells of phaeocystis. both morphotypes were grown under a range of irradiances at 0". 2". 5 " . 10" and 20°c. photosynthesis was measured as incorporation of h"c03-, and excretion as accumulation of doi4c during 24-hour incubations; growth rates of solitary cells were determined concurrently from changes in abundance. both morphotypes exhibited temperature-dependent asymptotic increases in pigment-specific photo synthesis with irradiance. saturation intensities increased with temperaturc. cell division by phaeoc.vstis solitary cells exhibited a functional response similar to photosynthcsis, although growth apparently saturated at lower irradiances. c:chla ratios were positively correlated with irradiance and inversely related to temperature, while c:n ratios were insensitive to these environmental parameters. colonies had higher c:chla and c:n ratios than solitary cells. pigment-specific excretion rates wcrc linear functions of irradiance, and exhibited temperature-dependent positive correlations with photosynthesis. percent extra cellular release (per) by both morphotypes was inversely related to tempcraturc. at low temperatures (0-5°c). solitary cells had higher photosynthesis rates than colonies at all irradiances. their excretion rates, however, were also higher, such that the per of solitary cells cxceeded those of colonies at 0°c and low irradiances at 2°c. no differences were detectable at 5°c. at higher temperatures. photosynthesis by solitary cells still generally exceeded that by colonies, but the colonies excreted con siderably more doc. thus, while solitary cells are more efficient at utilizing light for photosynthesis, they do not necessarily channel a larger proportion into biomass production. colonies, howcvcr. appear to be particularly stressed by higher temperatures and irradiances. peter g. verify, skidaway lnsfitute of oceanography, p . 0. box 13687. saoannah, georgia 31416. usa; theodore j . smayda. graduate school of oceanography, uniuersify of rhode island. kingston. rhode island 02881. usa; egil sakshaug, trondhjem biological sfafion, uniuersify of trondheim. bynesoeien 46, n-7018 trondheim, norway. introduction phaeocystis cf. pouchetii (hariot) lagerheim, a prymnesiophyte, is one of few marine phyto plankton taxa which exhibits phase alternations between free-living solitary cells and a gelatinous colonial aggregation of non-motile cells. while both stages are capable of rapid vegetative growth (kornmann 1955; kayser 1970), the colonies occur most prominently in the plankton. thou sands of non-motile cells (3-10 pm) may be con tained within colonies up to 10-20 mm in diameter (gieskes & kraay 1975; verity et al. 1988a, b; weisse & scheffel-moser 1990). the free-living solitary cells, of similar size, can be released from colonies, may persist indefinitely in the plankton, and may initiate formation of new colonies. in addition, macrospheres and microspores have been described (kornmann 1955; parke et al. 1971) which behave like asexual gametes. while they persist in some cultures, they have not been reported from natural populations, and their func tion remains obscure. blooms of colonial phaeocystis have been reported for 100 years (pouchet 1892; gran 1902). they are prominent in both coastal and oceanic waters, near the ice edge in both polar regions (braarud 1935; biggs 1982), and exhibit cross shelf distributional gradients influenced by frontal dynamics (iverson et al. 1979a, b). colony blooms are particularly well documented in norwegian fjords (sakshaug 1972; heimdal 1974; eilertsen et al. 1981), in the norwegian sea (smayda 1958; paasche 1960), and in the north sea (cadee & hegeman 1986). in contrast, archived samples from the continuous plankton recorder (cpr) imply a long-term decline in phaeocystis in all open sea areas of the north sea (owens et al. 118 p . g . verity. t. j . smayda & e . sakshaug 1989). this trend, however, may be applicable only to colonies since the cpr mesh size (ca. 250 pm) excludes small colonies and all solitary cells. this apparent conflict in historical trends of abundance emphasizes that the majority of the data are restricted to observations of phaeocysris colonies, and that our knowledge of i n situ behavior is based almost exclusively on colonial stage dynamics. the occurrence of solitary cells as an alternate planktonic stage complicates quan titation of phaeocysris bloom inception and its environmental regulation. although the role of life cycle phenomena has recently received atten tion (verity et al. 1988b). the abundance and temporal development of solitary cells has not generally been assessed, primarily due to dif ficulties in recognition of living phaeocysris in natural samples containing other phytoflagellates of similar size and morphology. this dearth of data biases our understanding of phaeocysris bloom dynamics. for example, phaeocysris is usu ally considered to be bipolar, with a preference for boreal and colder waters and the winter period in temperate seas (kashkin 1963). it occurs exten sively in polar seas up to the ice edge, and it has been reported from sea ice in both the arctic (hsiao 1980) and antarctic (whitaker 1977). but this bipolar nature is now suspect, as fhaeocysris cf. poucherti also occurs in subtropical and tropical water (guillard & hellebust 1971 ; leadbeater 1974; estep et al. 1984: verity unpubl. data). yet it rarely (if at all) produces the prodigious blooms commonplace in cold waters. why? the major structural difference between col onial and solitary stages is the large gelatinous matrix of the former. significant amounts of pho tosynthate are directed towards its manufacture (guillard & hellebust 1971; lancelot & mathot 1985; veldhuis & admiraal 1985) which, pre sumably, is energetically expensive. surprisingly, though, little is known of the relative photo synthetic and excretion potentials of the two mor photypes. it was the purpose of this study to provide such data and to investigate the role of temperature and irradiance i n influencing these parameters. methods unialgal cultures of phaeocysris cf. pouchefii (see sournia 1988) were isolated from the tromse sound near t r o m s ~ . norway, and grown in batch culture using polycarbonate flasks. manipulation of nutrient concentrations in sterilized "f" medium (guillard 1975) resulted in cultures over whelmingly dominated by colonies (f/50 silicate) or by solitary cells (f/2 silicate). simi lar responses to nutrient concentrations have been observed for other phaeocystis clones (guillard & hellebust 1971: verity & smayda 1989; turner et al. 1990). for both treatments, > 9 5 % of all cells belonged to a single morphotype, e.g. col onies or solitary cells. all media were prepared from the same batch of seawater colony cultures could not be cleaned entirely of their bacterial populations, probably due to their residual occurrence on the gelatinous sheaths of the colonies. healthy colonies, however. have few bacteria attached to their sur faces (verity et al. 1988b). cultures of solitary cells were deliberately not made axenic in order to better intercompare results with colonies. in both cases bacterial abundances (determined in dapi-stained epifluorescence microscope counts) were < 2 x 10'' cells/ml-', and bacterial biomass was an insignificant proportion of algal biomass. each morphotype was cultured at four to six irradiances and 14: 10 l : d photoperiods at o", 2", 5 " . lo", and 20" c. cool-white fluorescent light was attenuated using neutral density screen, and irradiance was measured with a biospherical instruments qsl-100 quantum sensor. cultures were adapted to experimental conditions for > 10 generations, after which identical aliquots were used to measure carbon, nitrogen, and chloro phyll a (chl a ) contents; photosynthesis and excretion rates; and population growth rates (of solitary cells only). for proximate analyses, samples were collected on 0.45 pm gelman a e filters using low vacuum pressures (< 50 mm hg difference between atmospheric pressure and vacuum pressure in the flask). chl a was extracted in the dark after grind ing i n 90% acetone, and measured fluoro metrically before and after acidification (holm hansen et al. 1965). filters for carbon (c) and nitrogen ( n ) determinations were pre-combusted at 400" c for 1 hour. carbon and nitrogen were measured with a hp185b chn analyzer (sharp 1974). growth and photosynthesis were measured as follows: two sets of 250-ml polycarbonate bottles, previously soaked in dilute hci and washed in photosynthesis, excretion. and growth rates 119 over time t (eppley 1972). note that i4c uptake rates described here approximate net rather than gross particulate carbon production, due to the relatively long incubations (24 hours). statistical tests were conducted according to sokal & rohlf (1969), with significance levels of p > 0.05 unless otherwise noted. correlations between photosynthesis and growth rates were analyzed by functional (geometric mean) re gressions as both parameters were subject t o inde pendent errors in measurement (ricker 1973; laws & archie 1981). deionized water, were gently filled with aliquots of the acclimated stock cultures. one set received an inoculum of 1.85 x lo5 becquerels (5 pci) of nah14c03 (new england nuclear), prepared using trace metal clean techniques (fitzwater et al. 1982). the other set was unaltered and was used to measure cell and colony size and abun dance, as well as growth rates of solitary cells. both sets were returned to their acclimation irradiances and incubated for 24 hours. in addition, an extra 14c bottle was wrapped in aluminum foil to provide a dark control. the i4c incubations were terminated by col lecting phytoplankton on gelman 0.45 pm ae glass fiber filters in triplicate subsamples. the filters were rinsed, placed in glass vials, acidified for 1 hour with 0.1 ml of 5 n hci to drive off residual inorganic 14c, and suspended in 5 m l of aquasol i1 scintillation cocktail. release of dissolved organic carbon (doc) was determined using methods modified after verity (1981). trip licate 8-ml aliquots of the 14c filtrate from each bottle were pipetted into 10ml glass test tubes. the ph was lowered t o 3.0 by acidification with hci, and samples were bubbled with air for 1 hour to purge inorganic carbon. five ml of each replicate were counted in 16 ml of aquasol 11. all samples were counted t o an accuracy of at least 5% using a beckman ls150 liquid scin tillation counter. quenching was corrected by the channels ratio method utilising a curve prepared from 14c-toluene. an isotope discrimination fac tor of 1.05 was applied. particulate and doc production rates were corrected for dark bottle activity, which was always a small fraction of light bottle counts. in colony cultures, the abundance of colonies i n triplicate 50 ml samples was enumerated using a stereomicroscope. cell abundance was calculated as (colony abundance) x (cells per colony), where cells per colony was determined as described in verity et al. (1988a). in solitary cell cultures, cell abundance of triplicate subsamples was measured in palmer-maloney chambers using a zeiss photomicroscope 11. cell growth rates were expressed as population doublings according to k(doub1ings . d-') = (l/t)logz (nt/n"), where n, and no were abundances at time t and 0. carbon (c) growth rates were also calculated by normalizing colony and cell photosynthesis rates to their c content according to k, (doubl. . d-l) = (l/t) log2 [(c + ac)/c], where c is the initial carbon content and ac is the production rate results colonies chlorophyll a-specific photosynthesis increased asymptotically with irradiance in a temperature dependent manner (fig. 1). the slopes of the p i curves increased with temperature (table i ) . saturation apparently occurred at 100-200 pmol photons m-2 s-l at 0" and 2°c; at > 150 pmol m-2 s-' at 5°c; at > 200 p o l photons m-2 s-l at 10°c; and at > 250 pmol m-2 s-l at 20°c. maximum observed photosynthetic rates were also tem perature-dependent, ranging from 2.2 (0°c) to 8.1 (20°c) g c (g chla)-' h-i. similar functional relationships are evident when photosynthesis is normalized t o colony carbon (fig. 2). carbon-specific incorporation increased asymptotically with irradiance, but saturation apparently occurred at lower light levels than that observed for pigment-specific photosynthesis. maximum rates ranged from 0.25 to 1.15 pg c . pg colony-c-' . d-i. table 1 . slopes of the light-limited portion (ab. g c . g chla-' . h-l ' p o l photons-' m-* s ' ) of the p-i curves at each temperature. bracketed values indicate 95% confidence intervals around slopes. fits of these data to the exponential model yielded the following equations: as (of solitary cells) = 0.033e"'"4"cmp ' and as (of colonies) = 0.026e"fwn"'emp lye ( 2 95% ci) temp. ("c) solitary cells colonies 0 2 5 10 20 ,032 (.006) ,025 (.005) ,035 (.008) .02y (.006) ,040 (.007) ,031 (.006) ,065 (.012) ,063 (.025) ,073 (.022) .077 (.012) 120 p. g. verity, t . j . smayda & e . sakshaug 11) , hi1 1 i i(pnole * rn.'*s.') fir. 1 . chl u-spccific photosynthesis ( p ) of colonies as a function of irradiance ( i ) . colonies were grown at 0" (0). 2 " (0). 5 o ( 0 ) . 10" ( m ) , and 20" (a,. error bars represent 1 sd. i ? . 1 _ i i i h 1im 200 3 0 0 i(pmole * m-* 5.') fig 2. carbon-specific photosynthesis (p) of colonies as a function of irradiance ( i ) . svmbols as in fig. 1 . carbon excretion was generally a small fraction of particulate fixation (fig. 3). percent extra colonial release ( p e r ) was inversely related to temperature and ranged from 1-7% (20°c) to 6 colony c (ng) fig. 4 . nitrogen ( n ) and carbon ( c ) contents of colonies grown at all temperatures and irradiances. error bars represent 1 sd. dashed lines illustrate 95% confidence intervals of regression slope geometric mean regresaion: colony n (ng) = 0.587 + 0 135 (colony c . ng): r: = 0.991. n = 24. 19% (o'c). the highest relative release occurred at higher irradiances at all temperatures. colony carbon and nitrogen were linearly related and independent of irradiance, tem perature, and colony size (fig. 4). the regression slope is equivalent to a mean c : n (by weight) of 7.41. colonies ranged from an average of 12 to 385 ng c , 2 to 49 ng n, and 228 to 2,560 cells per colony (data not shown), w i t h the largest colonies occurring at low temperatures. ratios of c:chla (by weight) exhibited tem perature-dependent asymptotic relationships with irradiance (fig. 5 ) . c : chla increased with irradiance, but this trend was most evident at low temperatures. ratios ranged from 65-99 (20°c) to 109-159 ( o o c ) . n:chl a ranged from %13 (20°c) to 15-20 (o'c) in colonies containing 0.1 0.4 (20°c) and 1.9-2.4 (ooc) ng chla per colony (data not shown). fig. 3. carbon cxcrction ( e ) of colonies exprcsscdas the pcrcent of total incorporation of "c into organic carbon ( p + e ) . s!mbols as in fig. 1 fir. 5 the ratio in colonies of carbon to chlorophyll (i (c :chl u ) . bg height. as a function of irradiance (1). symbols as in fig. i . photosynthesis, excretion, and growth rates 121 3 . i 0 i00 200 3w 400 i(pno1e m i s.') fig. 6. chl n-specific photosynthesis (p) of solitary cells as a function of irradiance ( i ) . symbols as in fig. 1 . 0 i 2 3 p(gc g cell c1 d-') fig. 8. comparison between cell-based population growth ( k ) and carbon-based photosynthesis ( p ) of solitary cells. symbols as in fig. 1 . geometric mean regression: k ( d i v . d ' ) = -0.023 + 0.986 [p. gc (g cell c ) ' . d-'i; 1' = 0.944, n = 24, solitary cells chlorophyll a-specific photosynthetic rates were temperature-dependent and increased with irradiance in a quasi-asymptotic manner (fig. 6). the slopes of the p-i curves (2) (symbols as in platt et al. 1980) increased with temperature (table 1). saturation was not clearly observed at the irradiances used at 0", 2", and 5"c, but was approached at 200400 pmole photons . m-* s-l at 10" and 20°c. maximum observed photo synthetic rates increased from 2.7 (0°c) to 12.2 (20°c) gc (g chla)-i h-i. q l o values for these maximum rates were not calculated as they may not represent actual maximum rates (e.g. pz). population growth rates of cells were also tem perature-dependent and exhibited asymptotic relationships with irradiance (fig. 7). saturation of cell division occurred at lower light levels than did photosynthesis, as observed for carbon specific photosynthesis of colonies. maximum growth rates increased from 0.3 (ooc) to 2.3 (20°c) doublings per day. photosynthesis measured in 24-hour incubations represents net carbon incorporation and, when normalized to cell carbon, is a measure of carbon growth rate. a comparison of this parameter to independently determined cell division rates (fig. 8) shows a slope not significantly different from 1.0 and an intercept not significantly different from 0, indi cating that the cells were in balanced growth. as with colonies, carbon excretion was gen erally a small fraction of particulate fixation (fig. 9). percent extra-cellular release (per) was an inverse function of temperature, ranging from 2% (20°c) to 10-20% (0°c). per increased with irradiance only at the colder temperatures. cell carbon (c) and nitrogen (n) were linearly related independent of irradiance, temperature. 1 0 100 200 3 0 0 1 0 100 2w 300 i(pnole ni' s.i) fig. 7. population growth rates of solitary cells ( k ) as a function of irradiance (1). symbols as in fig. i . fig. 9. carbon excretion ( e ) of solitary cells expressed as the percent of total incorporation of i4c into organic carbon (p + e ) . symbols as in fig. i . 122 p. g . verity, t . j . smayda & e . sakshaug and cell size (fig. 10). the regression slope is equivalent to a mean c : n ratio of 6.6 (by weight). cells ranged from an average of 10-1 10 pg c , 1 16 pg n , and 0.1-1.9 pg chla per cell (data not shown). weight ratios of c : chla exhibited tem perature-dependent asymptotic increases with irradiance (fig. 11). a trend particularly evident at lower temperatures. ratios ranged from 39-70 (20°c) to 51-100 (ooc). n : chla ranged from 6 10 (20°c) to 9-16 (ooc) (data not shown). discussion a major objective of this study was t o evaluate the comparative physiological potential of solitary cells and colonies of phaeocystis. as modulated by environmental parameters, to aid in under standing the bloom dynamics of this enigmatic 0 20 40 60 80 100 120 cell c (pg) fig. 10. nitrogen ( n ) and carbon ( c ) contents of solitary cells grown at all temperatures and irradiances. error bars represent 1 sd. broken lines illustrate 95% confidence intervals of regression slope geometric mean regression: cell n ( p g ) = 0 012 + 0.152 (cell c. pg); r? = 0.989. n = 24 i20 3 i i i i i i) i n ' 2 0 0 300 400 i(pnole. m.' s.'i f i g . /i. the ratio in solitary cells of carbon to chlorophyll a ( c : c h l a ) . by weight. as a function of irradiance ( i ) . symbols as i n fig. i . alga. despite a centennial of investigation (pou chet 1892; lagerheim 1893; gran 1902), factors influencing the inception and regulation of phae ocysfis blooms are poorly understood and for several reasons: (1) taxonomic uncertainties and the question of physiological clones; (2) incom plete description of the life cycle; (3) lack of physiological data on life cycle stages within a single clone; and (4) inability to distinguish soli tary phaeocysfis cells in natural assemblages of nanoplankton. the taxonomic confusion centers around species designation. although nine species have been described (sournia 1988), most records of blooms have been attributed to phaeocystis cf. pouchefiii and p . globosa, based primarily on dif ferences i n colony morphology. on the basis of culture experiments, kornmann (1955) concluded that p . globosa is a young stage (= jugend stadium) of p . pouchetii. o n the basis of eco logical data, gran (1902) favored their taxonomic separation. he characterized p . pouchetii as a cold-water form very sensitive t o higher tem peratures, and p . globosa as a hardier form which occurs during the warmest season. guillard & hellebust (1971) found that large colonies formed by their tropical clone resembled descriptions of p . globosa. this morphotype, absent in their cold . water clones, occurred in natural populations col lected near woods hole. the norwegian clone in the present study reproduced spherical colon ies, as did a u.s. east coast isolate (verity et al. 1988b), although very large, old colonies of both clones would occasionally show more elongate or lobed shapes (e.g. batje & michaelis 1986). we have insufficient evidence to definitively establish the identity of our clone or its relationship to the p . pouchetiilglobosa debate, and we accept the recommendation of sournia (1988) to refer to it as phaeocystis cf. pouchetii. cell size, and hence carbon/nitrogen content, may also vary considerably among and within clones. cells of phaeocystis cf. pouchetii are typi cally 3-8 pm in diameter (kornmann 1955; parke et al. 1971; chang 1984; jahnke 1989). distinctly larger cells up to 10-12 vm, however, have been reported (ostenfeld 1904; hallegraeff 1983; tande & bimstedt 1987). mean size of solitary cells in the present study ranged from 3 p m to 10 pm and was inversely related to temperature. carbon content was 10-11opg per cell. these directly measured values compare to those of 15 35 pg per cell for 4-7 pm cells (jahnke 1989), and to calculated carbon contents of 9.5 pg cell-' for 5 pm cells (weisse & scheffel-moser 1990) and 258 pg cell-' for 6-10 vm cells (tande & bamstedt 1987). the uncertain relationship discussed above between systematics and morphological varia bility is exacerbated by the possible occurrence of physiological clones, specifically thermal clones (guillard & hellebust 1971; guillard & kilham 1977). their cold-water clones grew between 4°c (lowest level tested) and 13"c, but not above 1 6 t , while a tropical clone grew between 17°c and 27"c, but died at 14°c. kayser's (1970) cold water clone grew best at 15°c (highest tem perature tested), but with difficulty at 5°c. simi larly, phaeocystis colonies from the north sea could not be induced to grow below 5°c (grimrn & weisse 1985; weisse et al. 1986), and rapid multiplication was observed only above 7°c. nat ural populations, however, occur at considerably lower temperatures (e.g. smayda 1958; eilertsen & taasen 1984; verity et al. 1988a, b). the clone in the present study could be cultured as distinct morphotypes over a broad temperature range, whereas another arctic clone of p. cf. pouchetii could not (jahnke 1989). these apparent con tradictions between lab data and field obser vations may reflect true physiological adaptations, inadequate culture methods or acclimation to growth conditions, or occurrence of multiple species. resolution requires full description of the life cycle of phaeocystis cf. pouchetii and definition of taxonomic status with respect to other species (jahnke 1989). the present data illustrate that different mor photypes of phaeocystis vary in their physiological performance even within a single clone. while colonies and solitary cells exhibited similar func tional responses to variations in irradiance and temperature, they differed substantially in mag nitude. at 0-5"c, solitary cells were always more photosynthetically efficient than colonies at a given irradiance (fig. 12). the slope of the light limited portion of the p-i curve for solitary cells exceeded that for colonies at 0-5"c, although the differences were not significant at p > 0.05 (table 1). this suggests that solitary cells were somewhat better adapted than colonies t o low light and temperature. however, chlorophyll a-specific excretion by solitary cells also exceeded that of colonies (fig. 13), such that solitary cells actually released larger portions of their photosynthate (per), especially at 0°c and 2°c. the per of photosynthesis, excretion, and gro wrh rates 123 6 5 a a 8 a 0 8 a 0 0 0 i i i 0 iw 200 i ( p n o l e m." 5.') fig. 12. comparison of chl o-specific photosynthesis ( p ) of colonies (open symbols) and solitary cells (filled symbols). as a function or irradiance ( i ) . cultures were grown at 0" (0). 2" (0). and 5°c ( a ) . data from figs. 1 and 6. (1 100 2 0 0 i ( p o l e m.' * 5.') fig. 13. comparison of pigment-specific excretion (e) of col onies (open symbols) and solitary cells (filled symbols), as a function of irradiance ( i ) . cultures were grown at 0" (0). 2" (0). and 5°c ( a ) . both morphotypes were indistinguishable at 5°c. the mb values were similar t o those of natural phaeocystis populations advected beneath sea ice (palmisano et al. 1986) and support those authors' conclusion that this alga is capable of adapting to a broad range of irradiances at low temperatures. the responses at higher temperatures were dif ferent. photosynthesis by solitary cells still exceeded that of colonies at 10-20°c (fig. 14), although the distinction was less than at q-5"c. values of ab were indistinguishable at 10-20°c (table 1). the most salient physiological shift was observed in carbon excretion rates (fig. 15). solitary cells excreted less carbon per unit of chlorophyll a than did colonies, particularly at higher irradiances. the net effect was that per of colonies exceeded that of solitary cells at 10 20°c. 124 p . g. verity, t . j. smayda & e . sakshaug 11 l l y l ? l y i 302 400 11 punole * m.' * s.' t f i ~ . 14. as in fig. i ? . but cultures grown at 10" (0) and 20°c (0). -k o h r 3 0 0 a 100 2 0 0 3 0 4 0 i(pnde * m-* s-') h g is. as i n fig. 13. but cultures grown at 10" (0) and 20°c (0). the major structural difference between these morphotypes is the large gelatinous matrix of the colonies (chang 1984) which apparently serves as a storage depot for labile organic carbon (lan celot & mathot 1985; veldhuis & admiraal 1985; lancelot et al. 1986). release of doc external to the colonies was generally only a small fraction of total incorporation. previous high per values for colonies of 1 6 4 4 % (guillard & hellebust 1971) were not confirmed in the present study. this difference may reflect that very dense cul tures were grown at low nutrient levels and high irradiances in the prior study. assuming that sub stantial amounts of photosynthate are channeled into the gelatinous matrix of the colonies (lan celot & mathot 1985; veldhuis & admiraal1985). the low rates of doc release measured here indicate that organic carbon associated with col ony mucus is retained on the glass fiber filters during low pressure filtration. this implies that biochemical parameters measured using filter-col lected colonies (figs. 4 and 5, 10 and 11; see also verity et al. 1988a) accurately represent the carbon, nitrogen. and chlorophyll a contents of the entire cell-matrix complex. the relatively low and constant c : n ratio of colonies (7.4) in the present study implies that most of the colony carbon is in the form of cells, or that organic nitrogen is also being deposited in the matrix, as suggested elsewhere for field populations (verity et al. 1988a). calculations imply that colonies with an overall c : n ratio of 7.4, in which cells ( c : n = 6.6: fig. 10) contribute < 50% of total colony carbon, should have an average c : n com position of the gelatinous matrix of < 9.0 (fig. 16). comparison of photosynthetic performances of colonies and solitary cells may offer insights into their latitudinal distributional patterns. from the perspective of light utilization and the gross par titioning of photosynthate, low temperatures and irradiances favor colonies. solitary cells are more efficient at utilizing light for photosynthesis, but they release a larger fraction of it as doc than do colonies. in contrast, high temperatures and irradiances favor solitary cells, and colonies appear to be more stressed. this stress may be reflected in the relatively low carbon growth rates of colonies at 10-20°c (fig. 2 ) . in addition to excreting more cabon, the colonies may be respir ing more, perhaps associated with the incipient stages of a life cycle transition from non-motile colony cells to motile swarmers. these general conclusions may, in part, explain why blooms of colonies apparently occur almost exclusively in colder waters, or at lower temperatures in tem d cell c i colony c (%) fig. 16. the c : n ratios of colony gelatinous matrix required to produce an overall colony c : n ratio of 7 . 4 when cells within the colonies have a c : n ratio of 6.6. colony matrix c : n ratio< are plotted against the '3contribution of cell carbon to tofal colon) carbon photosynthesis, excretion, and growth rates 125 diatoms. a high chl a:c ratio and a low p: for the large diatoms, however, counteract each other such that the maximum carbon-normalized pho tosynthetic rate ( p k ) , which expresses the maxi mum hourly growth rate, becomes more similar for the three groups than individual chl a:c ratio and p:. the similarity between the three groups in terms of the maximum growth becomes even more evident when growth rate at optimum light while the three groups of phytoplankton thus are not very different in terms of growth in strong light, the diatoms appear t o be more efficient than phaeocystis in low light. this can be inferred from the very high carbon-normalized photosynthetic efficiency d which again is due to the very high chl a:c ratio. there is thus no support for the notion that phaeocystis might dominate in cold is considered. perate regions. similarly, solitary phaeocystis cells are a ubiquitous component of tropical oceans, whereas colonies are rarely observed, and seldom in abundance. a comparison of our data for phaeocystis with data for cultures of large diatoms and phaeocystis dominated barents sea communities which con tain diatoms (table 2) reveals that all three differ significantly in terms of the chl a:c ratio and photosynthetic parameters. the barents sea com munities, not unexpectedly, exhibit properties somewhere between the two extremes: phaeo cystis colonies and shade-adapted large diatoms. above all, large diatoms and phaeocystis differ in that diatoms have a much higher chl a:c ratio, which has been emphasized previously (see saks haug 1989 for review). on the other hand, p t is 3 4 times higher for phaeocystis than for large table2. some properties of shade-adapted phaeocysris (15-45 ymol m-* ski) relative to other algae; 14 h day length. chlorophyll normalized (ab, p i ) and carbon-normalized (&. p$) photosynthetic parameters pertain to filtered samples. values in brackets represent light-adapted cells. temp solitary' colonies' large diatoms2 barents sea' chla:c 0" 2" 5 " a0 0" 2" 5" &(lo-') 0" 2" 5" p i 0" 2" 5" p6 0" 2" 5 " ik 00 2" 5 " clm(d-7 0" (obs.) 2" 5 " 0.014 0.013 0.015 0.032 0.035 0.040 0.45 0.46 0.60 3.4 4.5 5.5 0.048 0.059 0.083 106 129 138 [0.28] [0.44] (0.55j 0.008 0.048 [0.028] 0.031 [0.013] 0.011 0.014 0.025 0.023 [0.025] 0.020 [0.026] 0.029 0.031 0.20 0.32 0.42 2.2 2.5 3.1 0.018 0.028 0.043 1.1 0.8 0.038 [0.70] 0.62 10.341 11.71 0.9 11.61 [0.048] 0.028 [0.021] i this study thalnssiosiru nordenskioeldii and chuetoceros furcellarus; 25 and (brackets) 400 pmol m-l s-' (sakshaug et al. 1991). phaeocystis-dominated populations (viscous water) with diatoms, barents sea. based on data from f. rey presented in calculated as p: . 14 sakshaug & slagstad (1991 this volume): average for populations deeper than 70 m and (brackets) in the upper 20 m . 126 p. g. verity, t. j . smayda & e . sakshaug waters due to its particularly efficient utilization of low light. rather, the frequent dominance of phaeocysris in cold waters might be due to a high frequency of large initial stocks, or perhaps sedimentation and grazing rates may be par ticularly low for phaeocystis during initial phases of blooms. inception of phaeocystis blooms: a hypothesis temperatureor irradiance-dependent shifts i n performance, however, do not explain the incep tion of colony blooms, for which two mechanisms are known. one, only recently documented (ver ity et al. 1988b), is multiplication and enlargement of small colonies into larger ones, which then cleave into two daughter colonies of similar size and cell number. this process, however, is aug mented by or secondary in importance to the formation of new colonies from single cells (kor mann 1955; kayser 1970; parke et al. 1971). since the latter transformation occurs in nature at tem perature and light conditions under which either morphotype can be maintained in culture, it is likely that additional factors are implicated. numerous environmental factors have been invoked as bloom triggers. including temperature (jones & haq 1963); decreased concentrations of silicate and phosphate (jones & spencer 1970; gieskes & kraay 1975; van bennekom et al. 1975); trace metals (morns 1971; davidson & marchant 1987); and edaphic effects (jones & haq 1963). conclusive evidence in support of these hypotheses is lacking (cadee & hegeman 1986; weisse et al. 1986). nutrient concentrations per se do not appear to solely regulate dominance by or transitions among life cycle stages. for example. tropical waters, which tend to be oligo trophic, rarely show prodigious colony blooms. and chronic nutrient deprivation can also induce emigration of cells out of colonies, which suggests that low nutrient conditions favor solitary cells. however, colonies are inhibited and solitary cells are predominant when excess nutrients are added to cultures (see citations in methods). a key, consistent observation is that phaeo cystis colony blooms usually follow the spring diatom maximum, implying that perhaps chemical modification of seawater via biological con ditioning or secretion of allelochemic substances (smayda 1980) is a prerequisite for colony for mation. in this regard, there is the provocative suggestion that some species of the diatom genus chaetoceros produce a chemical compound which initiates the change from the motile to non-motile stage (boalch 1984). free-living phaeocystis cells can attach to surfaces by means of their flagella (not haptonema) (kornmann 1955; parke et al. 1971). and 8-cell colonies are found attached to chain-forming diatoms, frequently chaetoceros (smayda & verity unpubl. data). we propose that phaeocystis blooms develop through a two-step process requiring the sequen tial involvement of both stages in the life cycle. solitary cells increase in abundance due to their rapid growth rates and small size which prevents efficient retention by suspension-feeding met azoan herbivores (verity & smayda 1989). col onies develop from these cells, perhaps facilitated by the presence of diatoms, and in this stage phaeocysris blooms accumulate gradually from slow-growing populations subjected t o minimal population losses to predation. thus, by altering its growth rates, chemical composition, size, and palatability to herbivores, phaeocystis incor porates a suite of responses t o physical, chemical, and biological stimuli representative of those of the entire phytoplankton community. the chal lenge for future studies is to resolve details of the induction and regulation of these processes in the context of the life cycle of phaeocystis. references batje. m . & michaelis, m. 1986: phaeocystis pouchefii blooms in the east frisian coastal waters (german bight. north sea). mar. biol. 93. 21-27. bennekom. a . j . van. gieskes. w . w. c . & tijssen, s. b. 1975: eutrophication of dutch coastal waters. f r o c . soc. lond. b. 189. 359-374. biggs. d . c . 1982: zooplankton excretion and nh,+ cycling in near-surface waters of the southern ocean. 1. ross sea, austral summer 1977-1978. polar biology 1 . 55-67. boalch. g . t. 1984: recent blooms in the western english channel. ices special meeting on fhe causes. dynamics and effects of exceptional marine bloom and related events a9. 14. braarud. t. 1935: the “0st”-expedition to the denmark strait 1929. 11. the phytoplankton and its conditions for growth. hvalrdd. skr. norske vidensk.-akad., n o . 10. 1-173. cadee. g. c. & hegeman. j . 1986: seasonal and annual vari ation in phaeocystir poucherii (haptophyceae) in the west ernmost inlet of the wadden sea during the 1973 to 198.5 period. nerh. j . sea res. 20, 29-36. chang. f . h . 1984: the ultrastructure of fhat-ocysrx poucherii (prymnesiophyceae) vegetative colonies with special ref erence to the production of new mucilaginous envelope. n . z . j . mar. freshw. res. 18. 3 0 s 3 0 8 . photosynthesis, excretion, and growth rates 127 jones, p. g . w. & haq. s . m. 1963: the distribution of phaeocystis in the eastern irish sea. j. cons. perm. int. explor. mer 28, 8-20. kashkin, n. 1. 1963: materials on the ecology of phaeocystis pouchetii (hariot) lagerheim, 1893 (chrysophyceae). 11. habitat and specifications of biogeographical characteristics (in russian). okeanologiya, moscow 3(4). 697-705. trans lation ots: 63-41148, u.s. dept. commerce, office tech. services, joint publ. service. kayser, h . 1970: experimental-ecological investigations on phaeocystis pouchetii (haptophyceae): cultivation and waste water test. helgolander wks. meeresunters. 20, 195-212. kornmann. p. 1955: beobachtungen and phaeocystis-kulturen. helgolander wiss. meeresunters. 5 , 21b233. lagerheim, g . 1893: phaeocystis, nov. gen., grundat pa tetra spora poucheti har. botanbka notiser. 32pp. lancelot, c. & mathot, s. 1985: biochemical fractionation of primary production by phytoplankton in belgian coastal waters during shortand long-term incubations with i4c bicarbonate. 11. phaeocystis pouchetii colonial population. mar. biol. 86, 227-232. lancelot, c., mathot, s. & owens, n. j . p. 1986: modelling protein synthesis, a step to an accurate estimate of net primary production. phaeocystis pouchetii colonies in belgian coastal waters. mar. ecol. f r o g . ser. 32, 193-202. laws, e . a. & archie, j. w. 1981: appropriate use of regression analysis in marine biology. mar. biol. 65, 13-16. leadbeater, b. s. c . 1974: ultrastructural observations on nanoplankton collected from the coast of jugoslavia and the bay of algiers. j. mar. b i d . ass. u. k . 54, 179-196. morris, a. w. 1971: trace metal variations in seawater of the menai straits caused by a bloom of phaeocystis. nature 233, ostenfeld, c. h. 1904: phaeocysris pouchetii (hariot) lagerh. and its zoospores. archiv protistenk. 3 , 295-302. owens, n. j. p.. cook, d . , colebrook, m., hunt, h . & reid. p. c. 1989: long term trends in the occurrence of phaeocystis sp. in the north-east atlantic. j. mar. biol. ass. u . k . 69, 813-821. paasche, e . 1960: phytoplankton distribution in the norwegian sea in june 1954 related to hydrography and compared with primary production data. rpt. norw. fish. mar. inu. 12, 1 77. palmisano, a . c.. soohoo, j . b.. soohoo, s . l., kottmeier, s. t., craft, l. l. & sullivan, s. w. 1986: photoadaptation in phaeocystis pouchetii advected beneath annual sea ice in mcmurdo sound. antarctica. j . plank. res. 8 , 891-906. parke, m.. green, j. c. & manton, 1. 1971: observations on the fine structure of zoids of the genus phaeocystis (hap tophyceae). j. mar. biol. ass. u.k. 51. 927-941. platt, t., gallegos, c. c. & harrison, w. g. 1980: photo inhibition of photosynthesis in natural assemblages of marine phytoplankton. j. mar. res. 38, 687-701. pouchet, m. g . 1892: sur une algue pilagique nouvelle. c. r. hebd. soc. biol. ser. ix. 4 , 34-36. ricker, w. e . 1973: linear regression in fishery research. j . fish. res. bd. can. 30, 409-434. sakshaug, e . 1972: phytoplankton investigations in trondheimsfjord, 1963-1966. k. norske vidensk. selsk. skr. sakshaug, e. 1989: the physiological ecology of polar phy toplankton. pp. 61-89 in rey, l. & alexander, v. (eds.): proc. 6th conf. com. arct. lnt. e. j. brill, leiden, the netherlands. sakshaug. e . & slagstad. d. 1991: light and productivity of 427-428. i , 1-56. davidson, a . t. & marchant, h. j. 1987: binding of manganese by antarctic phaeocystis pouchetii and the role of bacteria in its release. mar. biol. 95, 481-487. eilertsen, h. c., schei, b. & taasen. j. p. 1981: investigations on the plankton community of balsfjorden, northern norway. sarsia 66, 129-141. eilertsen, h. c. & taasen, j. p. 1984: investigations on the plankton community of balsfjorden, northern norway. the phytoplankton 1976-78. environmental factors, dynamics of growth, and primary production. sarsia 69, 1-15. eppley. r . w. 1972: temperature and phytoplankton growth in the sea. fish. bull. 70, 1063-1085. estep, k. w., davis. p. g., hargraves, p. g. & sieburth, j . mcn. 1984: chloroplast containing microflagellates in natural populations of north atlantic nanoplankton, their identi fication and distribution, including a description of five new species of chrysochromulina (prymnesiophyceae). p rotisto logica 20, 613-634. fitzwater. s . e.. knauer. g . a. & martin, j. h. 1982: metal contamination and its effect on primary production measure ments. limnol. oceanogr. 27, 544-551. gieskes, w. w. c. & kraay, g . w. 1975: the phytoplankton spring bloom in dutch coastal waters of the north sea. neth. j. sea res. 9. 166-196. gran, h . h . 1902: das plankton des norwegischen nord meeres. rpt. norw. fish. mar. inv. 2 , 1-222. grimm, n. & weisse, t. 1985: die temperaturabhangigkeit des wachstums von phaeocystis pouchetii in batchkulturen. helgolander wiss. meeresunters. 39, 201-21 1. guillard, r. r. l. 1975: culture of phytoplankton for feeding marine invertebrates. pp. 2 w in smith, w. l. & chanley, m. h. (eds.): culture of marine invertebrate animals. plenum, new york. guillard, r . r. l. & hellebust. 1971: growth and the pro duction of extracellular substances by two strains of phaeo cystis pouchetii. j . phycol. 7 , 330-338. guillard, r. r . l. & kilham, p. 1977: the ecology of marine planktonic diatoms. pp. 372-469 in werner. d . (ed.): bot anical monographs 13, univ. california press. berkeley. hallegraeff. g . m . 1983: scale-bearing and loricate nano-plank ton from the east australian current. bot. mar. 26, 493 515. heimdal, b. r . 1974: composition and abundance of phyto plankton in the ullsfjord area. astarte 7, 17-42. holm-hansen, 0 . . lorenzen. c . j . . holmes, r . w. & strick land, j . d. h. 1965: fluorometric determination of chloro phyll. j . cons. perm. int. explor. mer. 25, 115-128. hsiao, t . c. 1980: quantitative composition, distribution, com munity structure and standing stock of sea ice microalgae in the canadian arctic. arctic 33, 768-793. iverson, r. l.. whitledge, t. e . & goering, j . j . 1979a: chlorophyll and nitrate fine structure in the southeastern bering sea shelfbreak front. nature 281, 664-666. iverson, r . l.. coachman, l. k.. cooney. r. t., english, t . s..goering, j . j . , hunt. jr.. g . l.. macauley. m. c . , mcroy, c. p., reehurg, w. s . & whitledge. t. e . 1979b: ecological significance of fronts in the southeastern bering sea. pp. 437 466 in livingston, r. j. (ed.): ecological processes in coastal and marine systems. plenum, new york. jahnke, j . 1989: the light and temperature dependence of growth rate and elemental composition of phaeocystisglobosa scherffel and p . pouchetii (har.) lagerh. in batch cultures. neth. j . sea res. 23, 15-21. jones, m. & spencer, c. p. 1970: the phytoplankton of the menai straits. j. cons. perm. int. explor. mer33. 169-180. 128 p. g. verity, t . j . sniayda & e . sakshaicg phytoplankton i n polar rnarinc ccosystcms a phvsiological view. pp. 6%85 in sakshaug. e . . hopkins. c . c. e & britsland. n . a . ( e d s . ) : proceedings of the pro mare sym posium on polar marine ecology. trondheim. 12-16 may 1990. polar research 10t11. sakshaug. e.. johnsen. g . . andresen. k . & vernet. m. 1991: modeling of light-dependent algal photosynthesis and growth: experiments with the barents sea diatoms thai ussiosira norderiskioeidii and chaetoceros furrellatils. deep sea res. 38. 41.s430. sharp. j . h . 1974: improbcd analysis for ’particulate’ organic carbon and nitrogen from seawater. limrtoi. oceanogr. iy, 984989. smayda. t j . 1958: phytoplankton studies around jan mayen island. march-april. 1955. nytt mag. bor. 6. 75-96. smayda. t . j . 1980: phytoplankton species succession. pp. 493-570 in morris. i . ( e d . ) : the physiologrcal ecology of phyfoplankton. univ. calif. press. berkeley. sokal. r. r . & rohlf. f j . 1969: biometry w. h . freeman. san francisco. c a sournia. a . 1988: phaeocwis (prymnesiophyceae): h o w many species? noua hedwigro 47. 21 1-217. tande. k . s & bimstedt. u . 19x7: on the trophic fate of phaeocysrir pouchetii (hariot). i. copepcd feeding rates on solitary cells and colonies of phaeocysris poucherii. sarsia 72. 313-320. turner, s. m.. malin g . . bigander. l . e . & leck. c . 10()0: interlaboratory calibration and sample analysis of dimethyl sulphide in water. m a r . chem. 29, 47-62. veldhuis. m j . w. & admiraal. w. 1985: transfer of photo synthetic products in gelatinous colonies of phoeocvsiis pou cherrr (haptophyceae) and its effect on the measurement of excretion rate m a r . ecol. prog. ser. 26, 301-304. verity. p. g . 1981: effccts of temperature, irradiance, and daylength on the marine diatom leprocvlindrus danicus cleve. i i . excretion. 1. exp. m a r . b i d . ecol. 55. 159-169. verity. p. g . & smayda. t . j. 1989: nutritional value of phaeocysris pouchetii (prymnesiophyceae) and other phy toplankton for acarria spp. (copepoda): ingestion, egg pro duction. and growth of nauplii. m a r . brol. 100. 161-171. verity. p. g . villareal. t . a . & smayda. t. j . i988a: eco logical investigations of blooms of colonial phaeocvstis p o u chetii. i abundance. biochemical composition. and metabolic rates. j. r a n k . res. 10. 219-248. verity. p. g , villareal, t . a . & smayda. t . j . 1988b: eco logical investigations of blooms of colonial phaeocysfis pou cherri. 11. the role of life-cycle phenomena in bloom termination. 1. plank. res. 10. 749-766. weisse. t . . grimm. n . . hickel. w. & martens. p. 1986: dynamics of phaeocystispoucherii blooms i n the wadden sea of sylt (germ bight. north sea). esr. coast. shelf sci. 23. 171-182. weisse. t. & scheffel-moser. u . 1 w : morphometric charac ter~stics and carbon content of phaeocysiis cf. poucherii (prymnesiophyceae). bof. m a r . 33. 197-203. whitaker. t m. 1977: sea ice habitats of signy island (south orkneys) and their primary productivity. pp. 75-82 in llano. g . a . (ed.): adaprarions wiihin antarctic ecosystems. smithsonian institution, washington. d.c. distribution and numbers of breeding ivory gulls pagophila eburnea in severnaja zemlja, russian arctic andrej e. v o l k o v and jacobus d e kokte volkov, a.e. & de korte. j . 1996: distribution and numbers of breeding ivory gull.; pagophila ehurnecr in severnaja zemlja, russian arctic. polar research 15 ( i ) , 11-21. .u b the ivory gull p u p p h i l a ehrrrneu has a semi-circumpolar distribution with breeding sites in thc high arctic. data about ivory gulls in thc severnaja zemlla archipelago (siberia) were collected from i991 t o 1995. the numbers of breeding ivory gulls and thcir cgg-laying period arc correlated w i t h the sea ice situation and weather during thc first part of the summer. w e estimate that the total potential hi-eeding population o f severnaja zemlja is about 2000 pairs, which makes up approximately 20% of the russian and 14% of the world ivory gull breeding population. the percentage of the total breeding population which actu;illy breeds varies annually. the most important breeding area of the ivory gull i n severnaja zcmlja i \ the sedov archipclago ( a . scdova) where a large colony (from 410 to about 1100 pairs in different years) was found on flat ground on domasnii island. colonies from 10 to 100 breeding pairs, mostly on steep cliff faces. occur on 0. oktjabr’skoj revoljucii and 0. bol’sevik. the ivory gull is included i n the kcd data book of russia. parts of severnaja zemlja. wlth important breeding sites, have heconie a nature rcscrvc. a . e. v d k o u . a l l r u s m n rrvrurch institute of nuture conseruniron, vserossijskij rinrrhio-is.sledouatel’~kij institut ochruny p r i r o d y ( v n i i p r i r o d u ) , 113628 m o s c o w . znamen.skoe-sudki russia; j . de korre. arctic centre, ljnioer,sity oj groningen. o u d e kijk in ‘ i jut.rtruu~ 26, p. 0. b o x 716. n1,-9700 as grorriqeti, the netherlands. introduction the ivory gull pagophila eburneu has a semi circumpolar distribution with breeding sites on high arctic islands from the central canadian arctic archipelago eastwards to severnaja zemlja (blomquist & elander 1981; il’icev & flint 1988). in the kussian arctic the ivory gull breeds in northern novaja zemlja (antipin 1938; authors’ observation, july 1995), on victoria island (govorucha 1970; vuilleumier 1995). in franz josef land (gorbunov 1932; rutilevskij 1957; tomkovic 1986; uspenskij & tomkovit 1986), in the islands in the kara sea (dement’ev 1951; e. e. syroeckovskij j r . , pers. comm. 1993; syroeekovskij jr., & lappo 1994; bangjord et al. 1994) and in severnaja zemlja (demme 1934; urvancev 1935; usakov 1951; bulavincev 1984; belikov & randla 1987; de korte rr volkov 1993; de korte et al. 1995). * location name explanation: a = archipelag (archipelago), b.= buchta (bay), f. = f o r d (fjord), g . = cora (mountain), l. = lednik (glacier), m. = mys (cape). 0 . = ostrov (island), oz. = ozcro (lake), p. = poluostrov (peninsula), pr. = proliv (strait), r . = reka (river) the first, data about ivory gulls in severnaja zemlja were collected by urvancev (1935) and usakov (1951) from 1931 to 1932, mainly in a. sedova (abbrevations and meanings of geo graphical names in severnaja zemlja are given i n table l), followed by demme’s (1934) obser vations from 1932 t o 1934. some data about the biology of this species were collected by bula vincev (1984) in the southern part of 0. bol’sevik in 1982. additional information about the dis tribution of ivory gulls in severnaja zemlja was also obtained by belikov rr randla (1987) and by the staff of the polar stations on 0. domasnij, 0. golomjannyj, 0. bol’soj, 0. malyj tajmyr (fig. 1)* and was surnmarised by m. v. gavrilo (de korte et al. 199s). from 1991 to 1995, volkov and de korte worked each summer in severnaja zemlja, mainly on 0. bol’sevik and in a. sedova. about 40% of the land area of the archipelago, about 37,600 km’, is covered with glaciers up to an elevation of 985 m.(fig. 1). from 1961 to 1991, at m. peseanyj on northern 0. bol’sevik, the average daily temperature was +o.o”c in july (de korte et al. 1995). from 1991 to 1995 the ice cover of the kara sea near the southern part of t ab le . 1 . b re ed in g si te s an d po ss ib le b re ed in g si te s (? ) o f iv or y gu ll s p ag op hi la e bu rn ea i n s ev er na ja z em lj a. f = c ol on y on f la t gr ou nd , c = c ol on y on c lif fs . i = c ol on y w ith o nl y iv or y gu lls , m = m ix ed c ol on y w ith o th er s ea bi rd s pe ci es . n um be rs ( lo ca ti on ) co rr es po nd w ith b re ed in g si te n um be rs i n f ig . 1. l oc at io n o bs er v. d at e t yp e si ze s ta te s ou rc e ?? ~ l ak ti on ov 1 93 6 d em m e 19 34 d e k or te e t al . 19 95 , a ut ho rs ' o bs er v. 1 99 5 d em m e 19 34 1. 0 . d li nn yj ? 19 31 -1 93 4 ? ? ? 2. 0 . s re dn ij 22 j ul y 19 32 fi 25 n es ts ch ic ks 3. 0 . d o m a h ij 11 j ul y 19 33 fl 10 0 ad ul ts fi rs t eg gs ju ly 1 99 2, '9 3, ' 94 , '9 5 23 j un e 19 48 r ne st s fi rs t eg gs lo gb oo k po la r st at io n 21 s ep te m be r 19 49 fi ne st s fl yi ng y ou ng lo gb oo k po la r st at io n 28 j un e 19 51 fi ne st s fi rs t eg gs lo gb oo k po la r st at io n 15 j ul y 19 93 f1 . 70 0 ne st s 30 % c hi ck s de k or te & v ol ko v 19 93 20 j ul y 19 94 fi 11 00 n es ts 10 % c hi ck s de k or te e t al . 19 95 26 j ul y 19 95 fi 41 0 ne st s 20 % c hi ck s au th or s' o bs er v. 1 99 5 30 j ul y 19 31 fi 10 0 ne st s eg gs , c hi ck s u sa ko v 19 51 u sa ko v 19 51 u rv an ce v 19 35 ju ly 1 93 2 fi 20 00 a du lt s eg gs , c hi ck s 20 a ug us t 19 34 f i 2 pa ir s ch ic ks d em m e 19 34 ju ne 1 93 9 f i 10 0 ne st s eg gs c ha ri to no vi t 19 40 6 a ug us t 19 92 0 d e k or te e t al . 19 95 5 a ug us t 19 95 f i 11 n es ts eg gs , c hi ck s au th or s' o bs er v. 1 99 5 ? c ? ? ? b el ik ov & r an dl a 19 87 19 91 0 v . i. b ul av in ce v, p er s. c om m . 19 91 19 93 0 au th or s' o bs er v. 1 99 3 a . h el bi g, p er s. c om m . 19 95 19 95 0 l ak ti on ov 1 93 6; u sa ko v 19 51 19 93 , ' 94 , '9 5 0 au th or s' o bs er v. 1 99 3, '9 4, ' 95 19 93 , ' 94 , '9 5 0 au th or s' o bs er v. 1 99 3, '9 4, '9 5 0 31 j ul y 19 31 f i ne st s ? 6. 0 -v a d ia ba zo vy e? 19 31 -1 93 2 ? ? 7. m . g or is ty j? ? ? ? u sa ko v 19 51 ; s em en ov 1 97 1 8. f . m at us ev it a? 1.5 j ul y 19 93 ? ? d e k or te e t al . 19 95 9. g . b az ar na ja ? ? ? ? u sa ko v 19 51 ; s em en ov 1 97 1 10 . b . s ka zo tn aj a 12 a ug us t 19 85 2 ne st s ch ic ks m .v . g av ri lo , p er s. c om m . 19 88 11 . p . p ar ii sk oj k om m un y? 19 31 -1 93 4 ? ? l ak ti on ov 1 93 6 au th or s' o bs er v. 1 99 3, '9 4, ' 95 19 93 , ' 94 , '9 5 0 19 83 0 b el ik ov & r an dl a 19 87 19 85 0 g av ri lo 1 98 8 12 . o z. i zm en fi vo e? 7 s ep te m be r 19 83 ? ? b el ik ov & r an dl a 19 87 13 . g . p lo sk aj a 15 j ul y 19 93 2@ 40 a du lt s ? d e k or te e t al . 19 95 20 j ul y 19 94 2 c 4 0 a du lt s ? d e k or te e t al . 19 95 14 . 0 . b ol 's oj ? 19 56 ? 1 lo gb oo k po la r st at io n 15 . m . m as si vn yj ? 19 31 -1 93 4 ? ? 16 . m . o lo vj an ny j? 19 j un e 19 31 em pt y ne st s ? l ak ti on ov 1 93 6: u sa ko v 19 51 au th or s' o bs er v. 1 99 3, '9 4, ' 95 19 93 , ' 94 , '9 5 0 u sa ko v 19 51 19 93 , ' 94 , '9'5 0 au th or s' o bs er v. 1 99 3, '9 4, ' 95 c. n a f? 4. 0 . g ol om ja nn yj 5 . b . s kr yt aj a? ?? c ? c ? c i ?? c '? c ? c ? ?? c7 c ? distribution and numbers of breeding ivory gulls 13 m w the archipelago varied in summer between 100% and 10% (v. a . spiekin, arctic and antarctic research institute, st. petersburg, pers. comm. 1994; authors' observations 1991-1995). the aim of our study was to survey the dis tribution of breeding sites and estimate the breed ing population size of ivory gulls in sevcrnaja zeml j a. methods from 19 july until 22 august 1991, volkov 6t pridatko (1994) worked in northwestern 0. bol'sevik near the station prima. in 1992 we studied birds in the same area from 15 july until 6 august. from 14 to 19 july 1993 we searched by helicopter for bird colonies on all the large and on some of the small islands of the archipelago. this work was continued on 0. bol'sevik and 0. domasnij from 20 t o 26 july (de korte & volkov 1993; de korte et al. 1995). from 19 to 22 july 1994, we observed colonies of ivory gulls on 0. bol'sevik and 0. oktjabr'skoj revoljucii from a helicopter and we landed on 0. domasnij and in r. ostancovaja. from 19 july to 10 august 1995 we made reconnaissance flights by helicopter in the southern part of the archipelago. on the ground we visited r. ostancovaja on 22 and 24 july, a. sedova from 23 july to 9 august, and r. sumnaja on 10 august. from 1991 to 1995 we investigated yearly the same areas and thus had the opportunity to study the population changes of ivory gulls. in 1991 and 1992 we found colonies by walking. we covered an unglaciated area of about 440 km2 in 1991, and 625 km2 in 1992. in 1993,1994 and 1995 we found colonies by surveys with a helicopter when we flew a total of 40 hours across and around all the large islands and 0. malyj tajmyr, 0-va diabazovye and a. sedova. in colonies up to 500 pairs we counted the number of pairs by counting ' the adult birds on the nest (one adult or two adults 1 on a nest = one pair). if possible we noted also nests without adults. in larger colonies we coun ~ ted an estimated percentage of the total colony 1 and extrapolated the results to the whole colony. for a study of the density of ivory gulls on land outside the colonies in 1991, we used the method of route census with a registration of length of route and distance from observer to each observed ivory gull on this route (celincev 1985). we investigated by walking all habitat types of 14 a . e . volkou & j . de korte / i / i 92' 96' jr _nr 10 . . . . . . . . . . . . . . . . . . . . m , 50 lrn , 0 ice-free land glacier a sea colony size (pairs) 0 0 = 1 10 0 = 11100 0 = 101-1200 loptev sea /v1 1 od' 1 0 4 ' n f the area: coastal tundra (38 km route), lowland watershed tundra (28 k m ) , foothill watershed tun dra (79 k m ) , and arctic deserts on mountains (44 km). censuses were done during 20-31 july, when part of the ivory gull population still was incu bating, and during 12-18 august, when all chicks had hatched. clutch sizes were investigated in the second half of july when all clutches had been completed. egg mortality was only studied in the second half of the incubation period, and chick mortality only in the first half of the chick rearing period. fig. 1. severnaja zemlja with place names referred to in this paper and possible brccding site5 of ivory gulls. explanation: open circle = breeding reported before 1980; solid circle = breeding reported in and after 1980; x = doubtful rcporh on breeding; p = station prima. numbers on map indicate breeding sites: 1 = 0 . dlinnyl 2 = 0. srednij 3 = 0. domasnij 4 = 0 . golomjannyl 5 = b . skrytaja 6 = 0 v a diabarovye 7 = m . goriatyj 8 = f . matuseviea 9 = g . razarnaja 10 = b. skazoenaja i 1 = p . pariiskoj kommuny 12 = o r . izmenfivoe 1.3 = g . ploskaja 14 = 0. bol'soj 15 = m. massivnyl 16 = m. olnvjannyj 17 = r. studenaja 18 = r. musketova 19 = o r . tvdrdoc 2 0 = m. pe\ftanyj 21 = r. ostancovaja (tundra) 22 = r. o\tancovaja (canyon) 23 = l . vojcechovskogo 24 = r . sumnaja 25 = 0 . malyj tajmyr. results breeding distribution and numbers fig. 1 and table 1 present the location of breeding places, probable breeding places and numbers of breeding pairs of ivory gulls in severnaja zemlja. a colony of about 700 breeding pairs was found on the southeastern part of 0. domasnij in july 1993 (de korte et al. 1995). this colony had about 1100 pairs in july 1994, and had 410 pairs in july 1995. from 1993 t o 1995, the colony had moved distribution and numbers of breeding ivory gulls 15 about 500 m. w e found a colony with 11 pairs on 0. golomjannyj in august 1995. in 1993 and 1994 we saw a colony with several dozen pairs near a glacier o n the cliffs of g . ploskaja. o u r observations in 1993,1994 and 1995 did not confirm reports by urvancev (1935), laktionov (1936), usakov (1951), semenov (1971) about breeding o n 0 v a diabazovye, m . goristyj, g. bazarnaja, m. massivnyj and m. olovjannyj. breeding of ivory gulls on p . pariiskoj kommuny (laktionov 1936) was not confirmed by field work performed in 1983 (belikov & randla 1987) and 1985 (gavrilo 1988). bulavincev (1984) and beli kov (belikov & randla 1987) found a colony with about 40 pairs in t h e basin of r . sumnaja (0. bol’sevik) in 1981, but in 1995 we did not see ivory gulls there. w e found a colony with 18 nests on flat ground o n t h e tundra about o n e kilometer east of r . ostancovaja in 1991. this breeding place was not occupied from 1992 to 1995. in 1991 we also found a colony with about 50 nests on accessible rocks with a south-eastern exposure, about 100 m from l. vojcechovskogo (volkov & pridatko 1994). within o n e kilometer from this colony there were six other occupied nests on inaccessible rocks. t h e accessible breeding site was deserted in 1992 and 1995, but several dozen pairs bred there in 1994. t h e inaccessible site was occupied in 1995. in 1992 we found four small colonies with a total of 24 breeding pairs some hundreds of meters apart on cliffs in the canyon of r. ostancovaja (de korte et al. 1995). ivory gulls bred there again in 1993 in one and in 1994 and 1995 in three of these four colonies (table 2). t y p e of colonies in severnaja zemlja ivory gulls breed o n flat tundra and o n cliffs, mostly in colonies, but also in single pairs (table 1). in most colonies on flat ground we found only ivory gulls, but in a large colony of ivory gulls on 0. d o m a h i j in 1993 we also saw a breeding pair of kittiwakes rissa tridactyla. o n t h e cliffs of r . ostancovaja ivory gulls bred together with kittiwakes, black guille mots cepphus grylle and glaucous gulls larus hyperboreus in 1992 (table 2). nests were situ ated on narrow inaccessible ledges in the middle part of the cliffs, about 15 m from the cliff top. most of the ivory gulls nested among the kitti wakes, but some pairs bred separately. colonies usually consisted of one group of table 2 . total numbers of seabird breeding pairs in four chff colonies with breeding ivory gulls i n r . ostancovaja in different years. pagophila rissa larus cepphus eburnea tridactyla hyperhoreu gryllr 1992 24 115 3 3 1993 2 30 2 some 1994 17-20 80-90 2 some 1995 23 45-50 7 2 3 nests, but o n the tundra near r. ostancovaja a colony had two groups of nests 600 m from each other. o n e group had four nests in a dry grass moss-lichen tundra, the second had 14 nests on gravel in a small stream. t h e mean distances between t h e nearest nests in t h e two groups were 1.5 and 6 m respectively. o n t h e cliffs of r . ostancovaja there were four groups in 1992, with distances of 300 t o 500 m between the groups. t h e colony o n 0. domasnij consisted of o n e group in a dry gravel habitat in 1993 and 1994. it consisted of a large and a small group, 40 m apart in 1995, when it was located in and around the remains of a polar station. t h e composition of t h e nest material is related to the vegetation in the colony area. in the cliff colony near l. vojcechovskogo ivory gulls used mostly mosses. in the tundra colony near r. ostancovaja nests consisted of vascular plant$. in t h e colony o n 0. domasnij, which in 1995 was situated in and around the remains of a polar station, the nests were made of mosses and small pieces of wood. breeding and breeding success in the colony near l . vojcechovskogo on 7 august 1991, about 10% of 50 pairs had eggs, 10% had down-covered chicks, 40% had chicks with small primaries and 40% had chicks with haif-grown primaries. in the colony on 0. domas nij, we observed 70% of the nests with eggs and 30% with chicks of two to five days old on 15 july 1993; 30% of the pairs still had eggs, and 70% had chicks of less than 10 days old on 22 july 1993. o n 26 july 1995, 20% of the nests had chicks, and on 5 august 80% of the nests had chicks. in these colonies the period of egg laying spanned three weeks o r more, while 70-80% of the eggs had been laid within two weeks after the first egg-laying. 16 a . e . volkov & j . de korte table 3. chick mortality in ivory gull colonies on severnaja zemlja. colony date breeding pairs (n) r . ostancovaja (tundra) 0. domasnij l. vojcechovskogo 28 july 1991 10 august 1991 23 july 1993 20 july 1994 26 july 1995 08 august 1995 07 august 1991 18 18 240 (1/3) 306 306 .so 220 (1/s) chicks (n) mean clutch brood size % hatched 1.6 70% 1.6 95% 1.4 70% 2.0 10% 1.4 20% 1.4 9s 70 1.4 90% living 20 24 360 40 88 390 .60 chick dead 0 3 90 ? 3 17 ? mortality 0% i170 38% ’? 3% 4% ? full clutches of ivory gulls had one to three eggs. mean clutch size varied from year to year from 1.4 to 2.0 (table 3). clutches with one or two eggs were the rule. however, in the large colony on 0. domasnij, we found clutches with three eggs in 1993 (< 1%), 1994 (15%) and 1995 (< 1%). chick mortality in the first weeks of life also varied from year to year with low mortality in 1991 and 1995, and relatively high mortality in 1993 (table 3). non-breeding birds in severnaja zemlja we saw outside the colonies only ivory gulls in completely white plumage. data about the numbers of ivory gulls outside the colonies were collected during route counts on the northwest part of 0. bol’sevik. in 1991 on the eastern coast of pr. sokal’skogo we counted an average of four birds in flight per two-hour period, but in 1992 only one per two-hour period. in 1991 we did not see groups of birds in the tundra outside the colonies. in 1992 such groups were recorded far from the coast and the station. near a lake, 4 km from the coast, i . n. safronova (pers. comm. 1992) observed a group of 72 birds on 23 july. in the upper part of r . ostancovaja near a glacier, 20 birds were recorded on 2 august. in 1991 we observed that on the tundra near pr. sokal’skogo density increased from 1.5 birds per km2 in the last 10 days of july to 6.6 birds per km2 in the middle of august. further inland, non breeding birds were rare. discussion breeding distribution severnaja zemlja is the easternmost area in the russian arctic where ivory gulls have been pro ven to breed (table 1, fig. 1). bannikov (1941) wrote about ivory gulls breeding on wrangel island, but without any specification. uspenskij (1963) supposed breeding of this species on bennett island (de long islands in the new siberian islands), but he only observed adult birds during the breeding period and did not find nests. breeding of the ivory gull on the new siberian islands and on herald island, without reference, mentioned by l0venskiold (1964) was never con firmed by more recent field observations (por tenko 1973; stisov et al. 1991). stisov et al. (1991) mentioned breeding ivory gulls in the de long islands, but without any reference. on the west ern coast of novaja zemlja, gorbunov (1929) saw ivory gulls but he did not prove breeding. a map of the breeding distribution of ivory gulls in the russian arctic by judin & firsova (1988) does not include bennett island and western novaja zemlja. a map with the world breeding dis tribution of ivory gulls by grant (1986) indicates bennett island, and such a map by haney (1993) indicates bennett island and western novaja zeml j a. population size the ivory gull is quite common in severnaja zemlja and 25 breeding sites have been located distribution and numbers of breeding ivory gulls 17 (table 1, fig. 1). among seabirds, only glaucous gulls, kittiwakes and black guillemots are more widespread (de korte at al. 1995). it is difficult to estimate the size of the breeding population of the ivory gull on severnaja zemlja because ivory gull breeding densities in the same area differ considerably from year to year. for example, the total numbers of breeding pairs counted in the same areas on northern 0. bol’sevik was 69 in 1991, 24 in 1992, 2 in 1993, 30-40 in 1994, and 27 in 1995. o n 0. domasnij, 0. srednij, 0. golomjannyj and perhaps 0. dlinnyj, ivory gulls bred on flat ground in the 1930s and 1950s (demme 1934; urvancev 1935; laktionov 1936; usakov 1951; logbooks polar stations), but we did not find colonies of ivory gulls on 0. srednij from 1992 to 1995. m . v. gavrilo found breeding pairs in 1985 in the southern part of b. skazoenaja (de korte et al. 1995). belikov & randla (1987) supposed that ivory gulls were breeding in 1983 on the river between oz. izmeneivoe and the sea. our observations in 1993, 1994 and 1995 did not confirm reports by urvancev (1935), laktionov (1936), usakov (1951), semenov (1971) about breeding on 0 v a diabazovye, m. goristyj, g. bazarnaja, m. massivnyj and m. olovjannyj. breeding of ivory gulls on p. pariiskoj kommuny (laktionov 1936) was not confirmed by field work performed in 1983 (belikov & randla 1987) and 1985 (gavrilo 1988). bulavincev (1984) and beli kov (belikov & randla 1987) found a colony with about 40 pairs in the basin of r . sumnaja (0. bol’sevik) in 1981, but in 1995 we did not see ivory gulls there. in the valley of r. musketova we found an old empty nest in 1992. reports about ivory gulls breeding in r. studiinaja and at m. peseanyj (bulavincev 1984; belikov & randla 1987) were not confirmed by our observations from 1991 to 1995. the staffs at the polar stations recorded ivory gulls breeding on 0. bol’soj and 0. malyj tajmyr (de korte et al. 1995), but we did not find them when we visited those places. reports of ivory gull colonies on the east coast of 0. komsomolec and b. skrytaja (belikov & randla 1987) were not confirmed by our obser vations in 1991 and 1993 nor by a. helbig in july 1995 (pers. comm. 1995). the numbers of breeding ivory gulls and their egg-laying period seem to be correlated with the sea ice situation and weather during the first part of the summer. the relatively low numbers of ivory gulls in 1992 can perhaps be explained by solid pack ice in the kara sea in june and july (v. a . spiekin pers. comm 1994; authors’ obser vation). in that year we observed quite large concentrations of non-breeding ivory gulls on the tundra. according to p. s . tomkovie (pers. comm. 1992), similar concentrations of ivory gulls were observed in 1981 near deserted colonies on graham bell island (franz josef land). in unfavourable years some birds occupy nests in the colony, but do not lay eggs. in 1992 pairs of ivory gulls were sitting on nests, without eggs or chicks, in a portion of the cliff colony in r . ostancovaja which had not often been used i n the past judging from the absence of nitrophilous lichens (xanthoria spec. and cafoplaga spec.) near the nests. these lichens usually can be observed in cliff colonies, which have been occu pied for decades, or centuries (salomonsen 1979). the estimated number of 100 pairs of breeding ivory gulls on the whole of 0. bol’sevik (bula vincev 1984) is. a minimum figure. we estimate that the total potential breeding population of severnaja zemlja is about 2000 pairs. the per centage of this population which actually breeds will vary annually. a total of about 8000 pairs may breed in other parts of the russian arctic: some thousands of pairs on the islands of kara sea (e. e. syroeekovskij jr., pers. comm. 1993; bangjord et al. 1994; syroeekovskij, j r . , & lappo 1994); some thousands on franz josef land (uspenskij & tomkovie 1986); and some hun dreds on victoria island (govorucha 1970; a. b. junak, pers. comm. 1992; vuilleumier 1995; forsberg 1995). a total of about 4000 pairs may breed outside russia, with less than 1000 pairs in svalbard (birkenmajer 1969; mehlum & bakken 1994), a maximum of 1000 pairs in greenland (evans 1984), and about 2400 breeding pairs in the canadian arctic (thomas & macdonald 1987). location of colonies on severnaja zemlja, ivory gulls breed in col onies on cliffs or on flat ground. on large islands, cliff colonies were situated up t o 20 km from the coast, but on the small island of 0. domasnij a flat ground colony was situated in some years less than 20 m from the coast. colonies on cliffs were located in inaccessible sites in canyons (e.g. r. ostancovaja) and on accessible sites near inland glaciers (e.g. l. vojcechovskogo). in northern novaja zemjja a small ivory gull colony in a canyon was also recorded (authors’ observation 18 a . e. volkou & j . d e korte july 1995). in svalbard ivory gull colonies were recorded on cliffs near glaciers (dalgety 1932; bateson & plowright 1959; l0venskiold 1964; flipse & d e roever 1964; birkenmajer 1969; d e korte 1972), o n cliffs facing the nearest coast (malmgren 1863; montague 1926; dalgety 1928; authors’ observation 1986), and on flat ground (lovenskiold 1964). cliff colonies and flat ground colonies have also been found in franz josef land (tomkovit 1986), greenland (salomonsen 1961; wright & matthews 1980) and canada (thomas & macdonald 1987). most colonies that we found constituted one coherent group of nests, but some colonies included separate groups of nests. this type of colony, with an example of six groups of nests, was also recorded on franz josef land (rutilevskij 1957). timing of egg-laying and breeding success the timing of egg laying varies from year to year and perhaps also from site to site. on 0. domasnij the first eggs were reported between 23 june (1948) and 28 june (1951) (logbook of the polar station). on 15 july 1 y y 3 we saw chicks there, which judging from their size, were two to five days old. this means that egg laying had started before 20 june if we allow for an incu bation period of 24 days (judin & firsova 1988). in the colony of r. sumnaja, five to seven day old chicks were observed on 29 july 1982 (bulavincev 1984), hence egg laying had started in the first days of july. demme (1934) reported the begin ning of egg laying on 0. srednij on 11 july 1933. the period of egg laying in a colony can he prolonged. in 1991, in the colony on the tundra near r . ostancovaja, w e saw chicks of about ten days old with developing primaries on 28 july but some clutches were still being incubated on 10 august. in 1982 in a colony on r. sumnaja, the first chicks hatched about 24 july, while on 13 august, two clutches were still being incubated (bulavincev 1984). in the five seasons (1991 to 1995) during which we did our observations, the timing of egg laying varied from the third week in june to the first days of july: according to 1981 data from graham bell island in franz josef land (tomkovie 1986) and 1982 data from the southern part of 0. bol’sevik (bulavincev 1984), egg laying began in the first days of july. in 1991 and 1993, with an early spring on 0. bol’sevik, egg laying began before 20 june. a similar early period of the beginning of egg laying was also recorded by the staff of the polar station on rudolf island in franz josef land (20 june) (rutilevskij 1957), where birds changed breeding place in the beginning of july and relaid. demme (1934) recorded the beginning of egg laying in 1934 on 11 july, which is relatively late, implying that the earliest chicks would fledge in early september. it is possible that these were relaid. in svalbard most juveniles fledge in late august (lovenskiold 1994; de korte 1972). the variation of the timing of egg laying and the relatively long period in which chicks can hatch and fledge successfully gives part of the ivory gull population a chance to reproduce also in unfavourable years because different timing gives different feeding opportunities. the main factor that determines the egg pro duction of ivory gulls is probably the possibility of finding food during the egg-laying period, part of which is synchronised with the primary moult (de korte 1972). food availability depends much on the distance from the breeding place to open water near sea ice (open leads and polynyas), where the birds can forage for amphipods and polar cod borrogadus saida, which we found in the stomachs of two and seven dead chicks, respectively. in exceptional cases they may also eat collared lemming dicrostonyx torquatus (kal jakin et al. 1985). in the first part of the summers of 1991 and 1995, when there was open water in the kara sea near the southern part of severnaja zemlja, ivory gulls bred successfuly and most chicks survived the frequent unfavourable weather with strong winds, rain and snow. in 1993, when large areas of the kara sea were covered with unbroken ice, chick mortality was much higher, although the weather was much milder. in 1992 many ivory gulls did not breed, probably because the whole kara sea near the archipelago was covered with unbroken ice (v. a . spitkin pers comm. 1994; authors’ observations). predation and site fidelity we did not record attacks from arctic skuas stercorarius parasiticus, pomarine skuas sterco rarius pomarinus and glaucous gulls larus h y perboreus in colonies of ivory gulls. however, snowy owls nyctea scandiaca which roam in small numbers to severnaja zemlja in years following a lemming year (de korte et al. 1995) sometimes take chicks from colonies on flat ground (authors’ observation 1995). distribution and numbers of breeding ivory gulls 19 around polar stations predation of eggs and chicks by dogs is possible; this was recorded on 0. domasnij in 1933 (demme 1934). in 1939 about 300 eggs were collected on 0. golomjannyj by personnel of the polar station (charitonovie 1940). at 0. trojnoj in the kara sea, the crew and dogs of the polar station took eggs in ivory gull colonies to a large extent in 1992 and 1994 (syroeekovskij, jr., & lappo 1994; bangjord et al. 1994). in summer, mammalian predators (arctic fox alopex lagopus, wolf canis lupus, and polar bear ursus maritimus) are rare on severnaja zemlja and they probably have only occasionally a significant direct influence on breeding success of the birds. on 0. trojnoj in the kara sea, a colony of ivory gulls was subject to heavy predation by arctic foxes and polar bears in the first week of july 1992, whereafter the ivory gulls changed breeding places and started to relay on 14 july (syroetkovskij, j r . , & lappo 1994). change or desertion of breeding sites is charac teristic for ivory gulls (dalgety 1928, 1932; bate son & plowright 1959; birkenmajer 1969; de korte 1972). birds often nest near the breeding places of previous years. previous-year nests near occupied colonies were found by bulavincev (1984) in southern 0. bol’sevik, by tomkovii (1986) in franz josef land, and by us in 1991 near r. ostancovaja. in 1993, on 0. domasnij at a distance of two kilometres from an occupied colony, we found four deserted colonies from previous years (de korte & volkov 1993). in 1994 the colony had moved about 100 m from the 1993 site, and again in 1995 by about 400 m. an accessible breeding site near l. vojcechovkogo which had breeding birds in 1991 and 1994 had none in 1992 and 1995. this characteristic of ivory gull ecology is often observed when a colony is located in areas accessible for predatory mammals; it is possibly a strategy to avoid predation, preventing terrestrial predators from learning the exact location of the colony. birds situated in inaccessible places tend to use use the same colonies each year, an example of which is the colony on the cliffs of r. ostancovaja. according to lsvenskiold (1964), ivory gulls never breed in a breeding place where eggs or young had previously been taken. on 0. srednij, where a military station is situated, colonies of ivory gulls have disappeared; but on 0. gol omjannyj, 0. trojnoj and victoria island where large polar stations were located, ivory gulls have continued to breed on f a t ground colonies (govo rucha 1970; authors’ observations 1995; bangjord et al. 1994; a. b. junak, pers. comm. 1992; vuilleumier 1995; forsberg 1995). if strong human disturbance disappears, the birds may reoccupy a breeding place that had previously been deserted. for instance, on 0. domasnij a colony disappeared after a station was build in 1930. the station was closed in 1954 and ivory gulls were again found breeding on the island in 1993, 1994 and 1995. threats and protection data about ivory gulls indicate changes i n num bers in different parts of the breeding area. a decrease in the number of ivory gulls in svalbard and a decrease in the area of distribution in the canadian arctic archipelago were recorded in the 1960s for unknown reasons (birkenmajer 1969; mcdonald 1976). for the russian arctic we d o not have much data about numerical ruc tuations and changes in the area of distribution of the ivory gull. the number of breeding pairs in a . sedova recorded in the 1930s is about the same as in the 1990s (about 1000). the numbers of ivory gulls t h a t breed in sev ernaja zemlja make up about 20% of the russian and about 14% of the world breeding population. in russia the ivory gull is a protected species and is included in the red data book of russia (but’ev 1983). the breeding places on the islands in the kara sea are included in the great arctic reserve, which has the status of a strict nature reserve, “zapovednik” (volkov & de korte 1994). the whole of franz josef land has the status of a nature reserve, “zakaznik” (huberth hansen et al. 1994; prokosch 1995). in 1996 part of severnaja zemlja has been given the status of a nature reserve, “zakaznik” (prokosch 1995). this means that a considerable part of the russian population of ivory gulls is now breeding in pro tected nature areas. from 1990 to 1995 the number of polar stations in the russian high arctic has severely decreased (de korte et al. 1995; authors’ observations 1995), thereby reducing the influence of human activity in these areas. however, extensive gold mining in open trenches in the southern part of 0. bol’sevik may have a negative impact on breeding places which have been reported in r . studenaja and r. sumnaja. in addition, the increasing scientific and tourist activities employing the use of heli 20 a . e . volkov & j. de korte copters in the high arctic, including severnaja zemlja, franz josef land and victoria island, could also have a negative effect on breeding places if these activities take place without any control (vuilleumier 1995; forsberg 1995; authors’ observations 1992-1995). acknowledgements.-netherlands marine re search foundation, plancius foundation (amster dam), van tienhoven foundation (amsterdam), willem barentsz foundation (groningen) and norwegian polar institute provided grants for field work and travel costs. the staff of the barc-company (st. petersburg) at station prima was very helpful when we worked in their area. h. a. kuperus (groningen) ,typed the manuscripts and tables. we thank the two unknown referees who gave us valuable com ments on our manuscript. n. cartwright (scot land) kindly corrected the english language. references antipin. v . m. 1938: fauna pozvonoenych severo-vostoka novoj zemli (fauna of vertebrate animals of northeast novaja zemlja). pp. 153-171 in vize v . ju. & urvancev n. n. (cds.): problemy arktiki (problems of rhe arctic) 2. glavsevmorput’, leningrad. bangjord, g . , korshavn, r . & nikiforov, v. 1994: fauna at troynoy (trojnoj) and influence of polar stations on nature reserve. izvestija cik, kara sea, july 1994. working report. klaebu: norwegian ornithological socicty. report 3, 1-55. bannikov, a. g . 1941: k ornitofaune ostrova vrangelja (about the ornithofauna of wrangel island). sbornik rrudoo gosu darstoennogo zoologifeskogo muzeja moskoo.~kogo uniu ersitefa (transactions of the state zoological museum of moscow university) 6. moskva. 197-202. bateson, b. p. & plowright, r . c. 1959: the breeding biology of the ivory gull in spitsbergen: brrrish birds 52 (4), 105 114. belikov, s. e . & randla. t . e . 1987: fauna ptic i mle kopitajustich severnoj zemli (fauna of the birds and mam mals of severnaja zemlja). pp. 18-28 in syroeekovskij e . e. (ad.): fauna i mcologija ptic i mlekopitajui2ich srednej sibiri (fauna and ecology of the birds and mammals of central siberia). nauka, moscow. birkenmajer, k . 1969: observations of ivory gull pagophila eburnea (phipps), in the south of west-spitsbergen. acta ornithol. i 1 (13). 461-476. blomquist, s . & elander, m . 1981: sabine’s gull (xemasabini), ross’s gull (rhodostethia rosea) and ivory gull (pagophila eburnea). gulls in the arctic: a review. arctic 34, 122-132 and 388. bulavincev, v. i. 1984: pticy ostrova bol‘sevik, archipelag severnaja zemlja (birds of bol’sevik island, archipelago of severnaja zemlja). ornitologija (ornithology) 19. izd. moskovskogo universiteta, moscow, 175-176. but’ev v. t. 1983: belaja eajka (ivory gull). pp. 28g-281 in krivenko (ed.): krasnaja knkniga r s f s r . ziuotnye. pticy (animals. birds). rossel’chozizdat, moscow. (3elincev, n. g. 1985. melody r a s h plotnosti naselenija iiv otnych po dannym m a r h t n y c h ueetov (methods of cal culation of animal population density using data of itinerary census). pp. 5-14 in ravkin, j . s. (ed.): prostramtoenno vremennaja dinamiku iioofnogo naselenija (dynamic of ani mal populations in time and space). nauka, novosibirsk. charitonovie, b . l. 1940: na ostmue domafnern souetkaja arktika (on domasnij island in the soviet arctic) 8. sel ’chozgiz, moscow. pp. 6g66. cramp, s . &simmons, k . e. l. (eds.) 1983: handbook ofthe birds of europe, the middle east and norrh africa. the birds of the western paiaearctic. oxford univ. press, vol. 111. waders to gulls. pp. 1-913. dalgety, c. t . 1928: the birds of edgc island. geogr. j . 72, 139-140. dalgety, c. t. 1932: the ivory gull on spitsbergen. british birds 26,2-7. de korte, j . 1972: birds observed and collected by de ned erlandse spitsbergen expedition in west and east spits bergen, 1967 and 1968-69. eeaufortia 257,197-232; 261,23 58. de korte, j . de & volkov, a. e. 1993: large colony of ivory gulls, pagophila eburnea, at domashniy island, severnaya zemlya. sula 7 (31, 107-110. de korte, j . de, volkov, a . e . & gavrilo, m. v . 1995: bird observations in severnaya zemlya, siberia. arctic 48 (3), 221-233. dement’ev, g . p. 1951: belaja tajka (ivory gull). pp. 41g414 indement’ev g . p. & gladkovn. a . (cds.): pticy sovetskogo sojuza. 3. sovetskaja nauka, moscow. english translation: dement’ev, g. p. & gladkov, n . a . (eds). 1969: birds of the sooiet union 3 . israel programme for scientific trans lation, ltd. jerusalem. demme, n. p. 1934: promyslovaja fauna severnoj zemli (the hunting fauna of severnaja zemlja). manuscript in state archive of scientific-technical documentation, st. peters burg. pp. 1-12u. evans, p. g . h. 1984: the seabirds of greenland: their status and conservation. pp. 49-84 in croxall j . p . , evans p. g . h . & schreiber r. w. (eds.): status and conservation of the world’s seabirds. icbp technical publication 2. cambridge. england. forsberg, m . 1995: ivory gulls flock to site of former military station. wwfarctic bulletin 3.95, 15. flipse, e . & roever j . w. de. 1964: ornithological observations made in spitsbergen in the summer og 1963. ardea 52 ( 4 ) , 21g222. gavrilo, m. v. 1988: pticy ostrova oktjabr’skaja revoljucija (severnaja zemlja): eislennost’, osobennosti raspredelenija, rekomendacii k ochrane (birds of oktjabr’skaja revoljucija island (severnaja zemlja): number, peculiarities of dis tribution, recommendations for protection). pp. 3 6 4 1 in andreev a. v . & kondrat’ev a . ja. (eds.): eiologifeskie p r o b k m y seuera. irurenie i ochrana ptic u mkosistemach severa (biological problems of the north. study and con servation of birds in the northern ecosystems). institut biol ogiteskich problem severa and vsesojuznoe ornito logiteskoe obseestvo, vladivostok. gorbunov, g. p. 1929: materialy po faune mlekopitajuseich i ptic novoj zemli (data on the fauna of mammals and birds of novaja zemlja). trudy po izuteniju severa (transactions for study of the north). 40. ntu vcnkh, moscow. pp. 169-239. dis gorbunov, g. p. 1932: pticy zemli franca iosifa (birds of franz josef land). trudy arktieeskogo instituta (transactions of the arctic institute) 4. gidrometizdat, leningrad. 244 pp. (german summary, die vogel von franz-josef land, 188 244). govorucha, l. s . 1970: ostrov viktorija (victoria island). pp. 359-363 in gerasimov 1. p. (ed.): souetskaja arktiku (morja i ostroua severnogo ledovitogo okeana) (soviet arctic (seas and islands of the arctic ocean)). nauka, moscow. haney, j . c. 1993: a closer look: ivory gull. birding25, 331 338. huhcrth hansen, j . p . , baxendale, €-i., kullerud, l . , lerke lund, h . e . , salberg, p. j. & smith, c. 1994: the state of protected areas in the circumpolar arctic 1994. caff habitat conservation report no. 1 , 1-154. directorate for nature management, trondheim. il’ieev, v. d . & flint, v. e. (eds.) 1988: ivory gull. in birds of the ussr. larids. nauka, moscow. (in russian) judin, k. a . & firsovd, a . v. 1988: belaja tdjka (ivory gull). pp. 51-57 in il’ifnv v. d. & zubakin v . a . (eds.): pticy sssr. cajkovye (birds of ussr. larids). nauka, moscow. kaljakin, v. n., belikov, s. e. & bulavincev, v. 1. 1985: kopytnyj lemming. discrosronyx torquarus, na ostrovach archipelaga severnaja zemlja (arctic lemming, discrostonyx forquatus, in the archipelago severnaja zemlja). zoo/. 2.. 788-789. laktionov, a . f. 1936: severnaja zemlja (north land). sev ernoe kraevoe izdatel’stvo, archangelsk. pp. 1-117. l@venskioid, h. l . 1964: avifduna svalbardensis. norsk polar inst. skr. 129. 1-460. malmgren, a . j. 1863: anzeichnungen uher die vogel-fauna spitsbergens. j. ornithol. 11, 358-387. mehlum, f. & bakken, v. 1994: seabirds in svalhard (norway): status, recent changes and management. bird life conser. ser. i , 155-171. mcdonald, s. d . 1976: phantoms of the pack ice. audubon 78 ( 3 ) , 3-19. montague. f . a . 1926: further notes from spitshergen. ibis 146148. portenko, l. a . 1973: pticy &kot.skogo poluostroua i ostroua vrangelja (birds of t u k o t s k i j peninsula and wrangel island). cast’ 2. nauka, lcningrad. 1-323. prokosch, p. 1995: nature reserve development in russia. wwfarctic bulletin 2, 12-13. rutilcvskij, g. a . 1957: 0 pticach ostrova rudol’fa (on birds o f rudolf island). trudy arktieeskogo nautno-issledovat el’skogo lnstituta (transactions of the arctic rcscarch insti tute) 205. morskoj transport, leningrad. pp. 87-95. salomonscn, f. 1961: ismagen (pagophila eburnea (phipps)) som ynglefugl i grbnland. dansk ornithol. foren. tidsskr. 5.5, 177-180. salomonsen, f. 1979a: ornithological and ecological studies in s.w. greenland (59”46’-62”27’ n. lat.). medd. g r g n l . 204. 1-214. semenov v. 1. 1971: prirodnye rajony severnoj zemli (natural regions of severnaja zemlja). trudy arcrifeskogo i antarcti ceskogo instituta (transactions of the arctic and antarctic reserch institute) 304. leningrad. pp. 167-209. stisov, m. s . , pridatko, v . i . & baranjuk. v. v. 1991: pticy oslroua vrangelju (the birds of wrangel island). nauka. siberian division. novosibirsk. 1-252. ,tribution and numbers of breeding ivory gulls 21 syroetkovskij, jr.. e . e . & lappo, e. g . 1994: materialy po faune i mkologii ptif ostrova sverdrup i ostrovov lzvestij cik (karskoe rnore)(data on fauna and ecology of birds of the lzvestij tsik islands and sverdrup island (kara sea)). pp. 111-151 in rogaeeva e. v. (ed.): arktifeskie tundry tajmyru i osfrovou karskogo morja: priroda. iiootnyj mir i problemy ich ochrany (arctic tundras of taimyr and kara sea islands: nature, fauna and conservation problems). vol. 1 . ipee ran, minpriroda rf. moscow. thomas. v. g . & macdonald. s . d. 1987: the breeding dis tribntion and current population status of the ivory gull in canada. arctic 40 ( 3 ) , 211-218. tomkovif, p. s . 1986: materialy po hiologii heloj edjki na ostrove greem-bell (zemlja franca iosifa) (data about the biology of the ivory gull on graham bell island (franz josef land). pp. 34-49 in il’ifev v. d. (ed.): aktual’nyeproblemy ornitologii (current problems of ornithology). nauka, moscow. tomkovit, p. s . 1990: k voprosu o vnegnezdovych per emeseenijach belych eaek (pagophila eburnea) (about move ments of nonhreeding ivory gulls). pp. 15cl151 in kuroekin e. n. (ed.): sourernennuja ornitologija (contemporary orni thology). nauka, moscow. urvancev, n. n. 1935: dva goda na severnoj zemle (two years in severnaja zemlja). glavsevmorput’, moscow-leningrad. usakov, g . a . 1951: po nechoienoj zemle (on untouched land). glavsevmorput’, moscow-leningrad. pp. 1-393. uspenskij, s. m. 1963: pticy i mlekopitajusfie ostrova bennetta (birds and mammals of bennett island). trudy arktifeskogo i antarktifeskogo ni1 (transactions of arctic and antarctic research institute) 224. morskoj transport, leningrad. pp. 18cl205. uspenskij, s. m . 1969: zirn’ u uysokich sirotach na primere ptic (life in high latitudes: a study of bird life). mysl’, moscow. 463 pp, translation in english: uspenskii, s . m. 1984. life in high latitudes: a study of bird life. american publishing co. pvt. ltd., new delhi, india. uspenskij, s . m . & tomkovie, p. s. 1986: pticy zemli franca iosifa i ich ochrana (birds of franz iosef land and problems of their conservations), pp. 63-76 in korotkevie e. s. & uspenskij s . m. (eds.): prirodnye kompleksy arktiki i uop rosy ich ochrany (natural complexes of the arctic and prob lems of their conservations). gidrometeoizdat, leningrad. volkov, a . e . & korte. j . de. 1994: protected nature areas in the russian arctic. polar rec. 30 (175), 299-310. volkov, a . e. & pridatko, v . 1. 1994: materialy po biologii beloj fajki (pagophila eburnea) na archipelage severnaja zemlja (on the biology of the ivory gull in the archipelago of severnaja zemlja). pp. 207-222 in rogaeova e. v. (ed.): arkcifeskie rundrv tajrnyra i ostrovou karskogo morju: prir oda, iiuotnyj mir i problemy ich ochrany (arctic tundras of tajmyr and kara sea islands: nature, fauna and conservation problems). vol.1. i p e e ran, minprirodd rf. moscow. vuilleumier f. 1995: a large colony of ivory gulls (fagophila eburnea) on victoria island, russia. alauda 63 (21, 135-148. wright, n. j . r . & matthcws. d . w. 1980. new nesting colonies of thc ivory gull (pagophila eburnea) in southern east green land. damk ornithol. foren. tidsskr. 74, 5%64. 393 pp newtontoppen granitoid rocks, their and rb-sr age a . m. teben’kov, y. ohta, ju. a . balasov and a. n. sirotkin geology, chemistry teben’kov, a. m . , ohta, y., balasov, ju. a. & sirotkin, a. n. 1996: newtontoppen granitoid rocks, their geology, chemistry and rb-sr age. polar research 15(1), 67-80. a post-tectonic caledonian granite in southern ny friesland has been fully mapped and the following new names are proposed: the chydeniusbreen granitoid suite, consisting of the raudberget granitoid body in the north; the newtontoppen granitoid body in the middle; and the ekkoknausane granitoid body in the south. the contact relationships, internal structures and distribution of various rock types infer an asymmetric lopolith or a harpolith-like body, a large sickle-shaped intrusion stretched in the direction of general tectonic transport, for the newtontoppen granitoid body. seven rock types are described in the newtontoppen granitoid and four emplacement stages are recognised. the major rock types seem to have an alkali-calcic to alkalic bulk rock chemistry and show a transition between iand s-type granite derived from anatectic melting of various protoliths under relatively high temperature conditions. possible later k 2 0 introduction modified the earlier formed rock types. a rb-sr whole rock age of 432 2 10 ma has been obtained by a seven point isochron with msdw = 2.59 and an initial sr isotope ratio = 0.715. this age is approximately 3 0 m a older than the previously obtained k-ar whole rock and rb-sr biotite ages, ca. 400 ma, which represents the period of cooling. the high initial sr isotope ratio supports the interpretation of an anatectic origin. a . m. teben’kou and a . n . sirorkin, polar marine geological expedition, ul. pobedy 24, 189510 lomonosov, st. petersburg, rwsia; y . ohta, norsk polarinstitutt, p. 0. box 5072 mujorstua, n-0301 oslo, norway; ju. a . balafov. geological institute, kola science centre of academy of sciences, ul. fersman 14. 184200 apatity, russia. introduction three intrusive bodies of granitoid rocks are known in southern ny friesland and northwestern olav v land, northeastern spitsbergen (fig. 1, inserted map, right). the granitic rocks have been known from as early as the latter half of last century (drasche 1874; nordenskiold 1875; gar wood 1899; nathorst 1910). backlund (1908) described two rock types and found that these granitoid rocks cut the precambrian hecla hoek succession. a petrographic summary was made by tyrrell (1922). oddel (1927) found the northern locality in the raudberget area, where the granitic rock is unconformably overlain by carboniferous strata, and thus concluded that the granitoids are of caledonian age. hjelle (1966) and kra sil’scikov (1969) made petrographic studies and described another separate locality in the south around the ekkoknausane area, in the upper reaches of nordenskioldbreen. these granitoid rocks have been called the chydenius granite (oddel 1927) or the chydenius batholith (harland 1959). however, as the place name “chydenius” does not exist, these names should be changed according to the suggestion of the norwegian stratigraphic committee. chy deniusfjella is actually outside the distribution area of the granitoid rocks. small nunataks con sisting of the granitoid rocks occur on both sides of chydeniusbreen; therefore, the following new names will be introduced here: the chyden iusbreen granitoid suite for the three bodies together, the raudberget granitoid body for the northern occurrence, the newtontoppen grani toid body for the middle massif, and the ekko knausane granitoid body for the southern locality (fig. 1 , inserted map, right). the rock compositions range from clino pyroxene-bearing granodiorite to granosyenite (hjelle 1966; krasil’seikov 1969), and the struc ture has been considered a batholith, the three \ \ \ \ 68 a . m . teben’kou et al. fig. 1. geological map of the newtontoppen granitoid body, with inserted location maps. inserted map in the right: rb = raudberget granitoid, n t = newtontoppen granitoid, ek = ekkoknausane granitoid, nb = nordenskioldbreen, t = terrierfjellet, f = ferrierfjellet. key: 1, grey granites; 2, (without ornament) pink-grey granosyenites; 3, granosyenite with aligned k-feldspar; 4, pegmatites; 5 , aplites (a), quartz-feldspar porphyry (qp) and lamprophyre (l); 6, estimated outlines of the rock types; 7, meta-clastic sediments of the veteranen group; 8, marbles of the akademikerbreen group; 9, cleavages of the metasediments; 10, mesoscopic structures within the granitoid rocks; 11, joints and their general trends; 12, observed and estimated boundary of the newtontoppen granitoid body; 13, estimated boundary between the veteranen and the akademikerbreen groups. dot and nos. with circle: observation points and sample localities (ref: all tables and figs. 2, 3, 4, 9 , 10). newtontoppen granitoid rocks, their geology, chemistry and rb-sr age 69 bodies being considered to be continuous under the surface (harland 1959). the ekkoknausane granitoid has been thought to be the roof of the batholith, rich in xenoliths and aplite-pegmatite dykes (hjelle 1966). krasil'seikov (1969, 1979) considered the exposures in ekkoknausane to be a group of small intrusions. the newtontoppen granitoid body cuts the strata of the metasediments of the lomfjorden supergroup (harland 1959). the cooling age has been given by k-ar whole rock ages of 385 406ma and rb-sr biotite ages of 401-402ma (hamilton et al. 1962). the present paper describes the field occur rences of all three bodies, the bulk rock chemistry, and the rb-sr whole rock isochron age from the newtontoppen granitoid body. contact relationships the contacts of the newtontoppen granitoids to the surrounding metasediments are evidently cross-cutting and intrusive. the surrounding rocks at the contacts are meta-arenaceous sedi ments of the veteranen group on the western side, and marbles and meta-pelitic rocks of the akademikerbreen group to the east, both of the lomfjorden supergroup of neoproterozoic age. the greenschist-subgreenschist facies metamor phic mineral assemblages in these rocks were locally superimposed by middle amphibolite fac ies assemblages in the thermal aureole produced by the granitoids, as much as 100m away from the contacts. the meta-arenaceous rocks at the southwestern contact (fig. 1, loc. 6) were con verted into andalusite-cordierite-biotite hornfel ses. the carbonate rocks at the northwestern (fig. 1, loc. 13) and middle eastern (fig. 1, loc. 23) contacts recrystallised into marbles with wollastonite, tremolite and quartz, and the meta arenaceous rocks at loc. 23 were converted into biotite-cordierite-quartz hornfelses. the contact surface dips 70-90" in the south and west, and 40-60" in the north and east, both beneath the granitoid body. thin aplite veins are confined within the body, striking subparallel to the contacts, and have not been seen intruding the surrounding rocks. no exotic xenolith has been found, but preferred alignments of elon gated melanozomes are distinct in the marginal part of the body. the raudberget granitoids form a small nun atak which is located ca. 12 km ne of the new tontoppen granitoid body, on the northern side of chydeniusbreen (fig. 1, inserted map, right), and the continuation to the latter is uncertain. the granitoid rocks are unconformably covered by flat lying carboniferous strata. the ekkoknausane granitoids (fig. 1, inserted map, right) consist of five nunataks, and are prob ably covered unconformably by the carbon iferous nordenskioldbreen formation. the granitoids show sharp intrusive contacts to the veteranen group quartzites and sandstones at terrierfjellet and ferrierfjellet, southeast of nor denskioldbreen. aplitic and granitic veins increase in the surrounding rocks approaching the contacts. a 50 m by 100 m granitoid mass cuts a quartzite-sandstone succession on the southern side of ferrierfjellet, possibly a stock or a dyke, though the boundary is covered by scree. at terrierfjellet, the westernmost part consists of gneissic rocks of the planetfjella group in fault contact with the veteranen group which forms the eastern part. the granitoid rocks cut a quartz ite-sandstone succession of the latter. at the three nunataks of ekkoknausane, in the uppermost reaches of nordenskioldbreen, the granitoid rocks are markedly heterogeneous, con taining quartzo-pelitic xenoliths with cross bed ding and ripple marks, dark patches and seams of melanocratic inclusions containing clinopyroxe ne-hornblende aggregates, and irregular blocks of gabbroic and gneissose granitic rocks with cat aclastic textures. some dark inclusions show orbicular structures. in summary, the ekkoknausane granitoid body is located near the boundary between the meso proterozoic planetfjella and neoproterozoic vet eranen groups, and the newtontoppen granitoid body is situated around the boundary between the veteranen and akademikerbreen groups. the raudberget granitoid body occurs within the akademikerbreen group, but near the eastern marginal fault zone of the neoproterozoic met asediments towards the carboniferous to the east. structure of the newtontoppen granitoid body alignments of k-feldspar phenocrysts and elon gated melanozomes are the main mesoscopic structural elements within the newtontoppen granitoid body. these structures are confined to 70 a . m. teben’kou et al. the peripheries of the body and are mainly oriented subparallel to the margins (fig. l ) , except for two measurements in the eastern and southeastern margins (locs. 23 and 27 in fig. 1). the k-feldspar phenocrysts sometimes include granulated plagioclase, especially near their rims. no granulated plagioclase has been seen in the non-porphyritic lithologies. this means that the k-feldspar phenocrysts were formed in the granu lated parts of the rocks; thus the k-feldspar por phyritic parts generally show the distribution of granulation, which in turn suggest locally granu lated parts in the body during emplacement move ments. the interior of the body is completely massive, and a weak planar structure represented by preferred arrangement of phenocrysts could be measured at only one locality. joints are regularly developed in the body on two steep dipping planes, one subparallel and the other subperpendicular to the contacts, and on one subhorizontal plane (fig. 1). small dip-vari ations of the horizontal joints infer a gentle dome like cooling surface over the body. the simple joint pattern throughout the body suggests a single cooling unit. later aplitic and quartz-feldspar porphyry dykes occur along the peripheries within the body from the north to the southeastern margin. these are obliquely cut by the steep dipping joints. a lamprophyre dyke occurs near the south eastern margin. this rock is petrogenetically unrelated to the granitoids, but often occurs near caledonian granite intrusions in svalbard (lau ritzen & ohta 1984; kovalyova & teben’kov 1986). weak post-consolidation movements have been recorded as slips along joint surfaces near the western margin (loc. 8 in fig. l), where the surfaces are covered by chlorite. a 3 m-wide shear zone with hematite has been observed at val letteknausen, on the southern side of chy deniusbreen (loc. 13 in fig. l), separating the porphyritic granite from carboniferous white grey limestones, without any thermal effect. the newtontoppen granitoid body is assumed to be an asymmetric lopolith or a harpolith-like shape; a large sickle-shaped intrusion elongated in general tectonic transport direction, based on the following evidence: (1) steep dips of the con tact surfaces beneath the body in the southwest and moderate dips from north to southeast, (2) relatively rich melanozomes in the south and southwest, and (3) the distribution of aplite dykes from the southeast to the northern margin. this suggests that the body has a steep root in the southwest and an extended thinner tongue to the east and north. the exposed thickness of the body is about 900 to 1ooom in the southern to southwestern parts. the roof of the harpolith-like body has been removed by erosion. the contact hornfelses having andalusite-cordierite assem blages infer low pressure conditions at a relatively shallow depth. petrography backlund (1908) described porphyritic and non porphyritic varieties from the granitoid rocks, while oddel (1927) wrote that these varieties are caused by various degrees of surface weathering. hjelle (1966) reported that the modal com positions of the rocks range from granodiorite to granosyenite. the following rock types have been recognised in the newtontoppen granitoid body in the field, with their field names, referring to streckeisen (1976): 1. melanozomes and dark grey granosyenites, 2. pink-grey granosyenites and pink quartz 3. grey granites, 4. granosyenite with aligned k-feldspar pheno 5. aplitic veins, 6. pegmatites, 7. quartz-feldspar porphyry. monzonites, crysts, melanozomes and dark grey granosyenites these rocks are represented by melanozomes and dark varieties of the more common pink-grey granosyenites. the melanozomes (sample nos. 1, 2 in tables 1 , 2 and figs. 2-4) occur as inclusions in various types of granosyenites near the margin of the body, as round and/or elongated patches and seams of several cm to 4-5 m in length, with partly diffused margins. they contain more mafic minerals and less quartz than the host rocks, with modal compositions of melanocratic granosyen ite. their constituent minerals are the same as other granosyenites and they are considered to be cognate inclusions. some gabbroic inclusions found in the ekkoknausane body could be similar in origin. the melanozomes contain as much as 10 modal % clinopyroxene which is always sur newtontoppen granitoid rocks, their geology, chemistry and rb-sr age 71 . 5 4 f 3 0 2 1 ab or 50 4 0 30 20 fig. 2. cipw normative ratios, q-or-ab diagram. key: solid triangles = melanozomes and dark grey granosyenites; solid circles = pink-grey granosyenites; crosses = grey granites; oblique crosses = pink quartz monzonites; open triangles = granosyenite with aligned k-feldspar; open squares = aplites; circle with dot = quartz-feldspar porphyry. these symbols are the same in all figures, except for figs. 9 and 10. broken curves: eutectic minimums at various vapour pressures. nos. refer to the first column of table 1. 60 60 fig. 3. afm diagram. th-ca dividing curve: irvine & baragar (1971); between the two broken curves: common c a field (ringwood 1974). same nos. and symbols as fig. 2. rounded by green prismatic hornblende (ca 15 modal %). brown biotite occupies ca. 10 to 15 modal % of the rock. k-feldspar occurs inter stitially in most rocks, but it is locally phenocrystic and includes many grains of prismatic plagioclase and mafic minerals. the dark grey granosyenites (sample nos. 3 , 4 , 5 in tables 1, 2 and figs. 2-4) are more coarse 1 . i 75 65 sio2 ’o 55 60 fig. 4 . n a 2 0 + k 2 0 and cao vs. s o l diagram, in weight percent. alkali-subalkali division: irvine & baragar (1971). the alkali-lime index is roughly estimated between 56 and 47. same nos. and symbols as fig. 2. grained than the melanozomes, having similar modal compositions, locally with k-feldspar por phyritic texture. they show a gradational tran sition contact with the pink-grey granosyenites. syenites, monzonites and granites the differences in modal compositions of quartz and mafic minerals and the colour of k-feldspar discriminate these rock types; pink-grey grano syenites (sample nos. 6 t o 9 in tables 1, 2 and figs. 2 4 , pink quartz monzonites (sample nos. 15 to 17 in tables 1, 2 and figs. 2-4) and grey granites (sample nos. 10 to 14 in tables 1, 2 and figs. 2-4). these rocks occupy ca.90% of the new tontoppen granitoid body. the grey granite occu pies the center of the body, while the other two rock types are irregularly mixed and occur around the grey granite. no cross-cutting relationship has been observed between them and the borders are gradational. all of these rocks are k-feldspar porphyritic; phenocrysts are 4 4 cm in size and occupy ca. 4 s 50 modal % of the rocks. k-feldspar always exceeds plagioclase, and microcline twins are dis tinct in the k-feldspars of the granosyenites and quartz monzonites, while not distinct in the grey granites. the matrices of all three rock types show a coarse-grained, hypidiomorphic texture and consist of k-feldspar, quartz and plagioclase in similar amounts (5-20 modal % each), biotite and hornblende (5-20 modal % each) and cli nopyroxene. clinopyroxene is absent in the grey 72 a . m. teben’kov et al. table 1. major element compositions of granitord rocks from the newtontoppen granitoid body. the first numbers in the second column correspond t o the locality numbers in fig. 1. melanozomes and dark grey granosyenites: 1-5; pink-grey granosyenites: b 9; grey granites. 1g-14; pink quartz monzonites: 15-17; granosyenite with aligned k-feldspar: 18; aplites: 19 and 20; quartz porphyry: 21. no. 17 is a quartz monzonite from the raudberget granitoid body. the sample numbers are common in all tables and figures. i = average i-type granite, s = average s-type granite from taylor & mclennan (1985) loc. no. in no. in figs. 2-5 fig. 1 s i 0 2 tio, al2o3 f e 2 0 3 feo mno mgo cao n a 2 0 k,o p 2 0 s ig. loss total 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 i s 1-3 60.40 1.00 13.66 0.97 5-2 59.68 1.20 13.26 1.00 8-1 60.64 0.93 13.52 0.65 23-2 60.39 1.06 12.76 1.37 5-1 61.55 0.95 12.40 1.02 9-1 61.20 0.88. 14.67 0.89 11-1 60.03 0.95 15.30 0.95 8-2 62.42 0.68 13.74 1.90 x-3 59.85 0.84 14.91 0.65 1-1 69.13 0.40 14.12 0.32 18-1 69.33 0.50 13.74 0.08 19-1 71.01 0.40 13.68 0.22 20-1 66.83 0.60 14.14 0.85 1-2 68.94 0.50 12.83 0.72 13-8 63.16 0.83 14.73 0.06 15-1 64.62 0.65 15.64 0.70 34-1 63.66 0.68 14.90 1.33 28-2 63.49 0.68 14.84 1.12 1-4 71.74 0.33 14.11 0.35 23-3 76.96 0.11 13.07 0.10 1-5 67.15 0.50 16.16 0.55 69.17 0.43 14.33 70.27 0.48 14.10 4.08 0.13 5.02 4.30 2.17 4.11 0.10 7.12 2.86 1.94 4.29 0.10 4.41 3.72 2.37 4.07 0.13 5.39 4.27 2.04 3.60 0.08 4.21 3.72 2.45 3.90 0.10 4.41 3.44 2.57 4.11 0.10 4.51 3.29 2.13 3.06 0.07 3.78 2.83 2.56 5.11 0.11 4.04 3.81 2.56 2.14 0.05 1.30 1.86 3.57 3.03 0.05 1.41 2.15 3.47 2.10 0.04 1.41 1.43 3.29 2.70 0.07 2.41 2.58 2.71 1.93 0.05 1.90 1.72 3.13 3.54 0.06 3.21 3.01 3.45 3.06 0.07 1.10 2.44 3.01 2.81 0.08 2.80 3.23 2.96 2.88 0.08 2.45 3.54 2.96 1.89 0.03 0.80 1.43 2.97 0.29 0.62 3.22 2.16 0.04 1.20 1.72 3.23 3.23 0.07 1.40 3.20 3.13 3.37 0.06 1.42 2.03 2.41 6.47 0.37 5 62 0.60 6.64 0.47 7.06 0.32 7.11 0 4 5 6.01 0.45 6.22 0.46 6.30 0.37 5.81 0.38 5.17 0.22 4.88 0.26 5.02 0.22 5.46 0.35 6.06 0.29 5.34 0.41 6.20 0.37 5.72 0.28 6.60 0.12 5.00 0.16 5.72 0.22 5.60 0.22 3.40 0.11 3.96 0.15 1.35 99.92 2.41 99.90 2.35 100.09 1.26 100.12 1.71 99.25 1.54 100.06 1.77 99.82 2.09 99.86 1.45 99.61 1.67 99.95 1.03 99.93 1.23 100.05 1.28 99.98 1.65 99.72 2.14 99.94 1.91 99.77 1.14 99.59 1.06 99.86 1.15 99.96 0.42 100.53 1.48 100.01 98.47 98.25 table 2. trace element analyses. i and s: same as in table 1. no. in no. in figs. 2-5 fig. 1 li rb cs sr ba sc y zr v cr co ni cu ga 1 2 3 4 5 6 7 10 11 12 13 14 15 16 17 18 19 20 21 i s 1-3 5-2 33 8-1 40 5-1 23 9-1 33 11-1 41 1-1 62 18-1 19-1 31 20-1 48 1-2 47 13-8 18 15-1 34-1 28-2 23 1-4 23-3 1-5 23-2 373 289 329 278 286 335 251 324 317 262 278 132 100 470 7 520 1800 15 500 1600 200 800 7 560 1300 11 560 2000 11 660 2200 1s 350 700 560 580 11 440 900 11 640 900 13 390 800 12 520 1200 470 1400 500 1500 11 780 1800 100 320 <loo <loo 200 300 253 520 139 480 13 21 13 22 10 20 9 22 9 22 14 18 13 22 5 14 5 14 6 13 8 19 5 13 10 18 8 19 10 12 8 16 14 10 <5 <5 <5 13 15 27 14 32 560 1100 430 720 560 300 350 190 300 190 300 190 390 300 400 400 160 82 290 143 170 74 100 82 56 74 94 82 27 32 26 54 36 64 60 70 54 25 1 5 26 74 72 580 360 230 530 250 200 200 , 72 400 63 100 96 210 170 95 100 600 160 120 27 46 18 26 18 19 19 20 20 5 12 12 12 8 14 14 14 14 5 <5 8 12 13 280 250 66 100 100 74 80 13 34 38 40 22 68 70 34 60 24 120 50 9 17 9 19 31 15 27 16 19 15 20 24 22 17 18 16 <5 14 5 9 23 12 10 10 4 14 <5 20 12 22 18 15 19 14 18 9 8 11 14 19 11 16 12 17 newtontoppen granitoid rocks, their geology, chemistry and rb-sr age 73 granites, while it occurs as much as 2 modal % in the granosyenites. the phenocrystic k-feldspar contains inclusions of prismatic plagioclase grains, often showing granulated texture with overgrowth of sericite, biotite and hornblende. this suggests that a large part of the k-feldspar was formed after the inclusion minerals and the granulation of plagioclase. albite usually rims the k-feldspar phenocrysts. green hornblende shows prismatic and idiomorphic shapes, 0.5-2.5 mm in length, and rarely includes small grains of prismatic cli nopyroxene. the clinopyroxene has optical par ameters of the diopside-hedenbergite series. brown biotite flakes, 0.5-1.5 mm in length, con tain zircon and orthite. conversion of the biotite into chlorite is not common. accessories are idiomorphic sphene, often up to 1.5 mm in length, bipyramidal orthite with zonal structures and twins, zircon, monazite, apatite and opaques. orthopyroxene, anatase and fluorite have been identified by the x-ray powder diffraction method in the heavy mineral fractions separated from twelve samples. opaques are magnetite, hemat ite, ilmenite, sphalerite and molybdenite. granosyenite with aligned k-feldspar phenocrysts this granosyenite (sample no. 18 in tables 1, 2 and figs. 2 4 ) exposes in the southeastern corner of the newtontoppen granitoid body and cuts the pink-grey granosyenite at loc. 28 (fig. 1). the cross-cutting rock is characterised by subparallel alignment of long prismatic feldspars, 3-5 cm long. total feldspars comprise ca. 80-90% of the rock. phenocrystic k-feldspar is microperthitic, occupying ca. 50% of the rock. k-feldspar grains in the matrix are usually prismatic, 2-5 mm in length. plagioclase grains are also prismatic, 0.5 1.0 mm long in the matrix, with compositions ranging from oligoclase to andesine, showing nor mal zoning. quartz and biotite occupy 5-10 and 1-5 modal %, respectively, of the rock in the matrix. aplitic veins aplitic veins (sample nos. 19 and 20, in tables 1, 2 and figs. 2-4), 40-50cm wide and as much as 1001-11 long cutting all previously described rocks, occur near the margins of the body. most of them strike subparallel t o the margins with various dips. the aplites are fine-grained, biotite-bearing rocks, having k-feldspar, plagioclase and quartz in roughly equal amounts in a hypidiomorphic texture. biotite flakes comprise ca. 1-2 modal % and have a dark green colour. pegmatites pegmatite veins are rare, they are less than 50 cm in width and cut all previously described rocks. the pegmatites have muscovite-k-feldspar-bear ing assemblages and some veins show zonal struc tures constituting one or more of the following zones; muscovite-quartz-k-feldspar, rnuscovite k-feldspar, quartz-k-feldspar and quartz mon omineralic zones, from the margin to the core. quartz-feldspar porphyry a dyke of this rock (sample no. 21 in tables 1, 2 and figs. 2 4 ) , 1-1.5 m thick and ca. 50 m long, occurs along a joint in the pink-grey granosyenite, with a nw-se strike and a subvertical dip in the southeastern part of the body (loc. 1, fig. 1). the dyke is considered to be the latest intrusion. the rock is massive and has a fine-grained mic rofelsic matrix of quartz and feldspars. large flakes of biotite and phenocrysts of feldspars and quartz are characteristic. the biotite shows a dark green to almost black pleochroism. quartz pheno crysts show corroded outlines and rarely have an idiomorphic shape. k-feldspar is short prismatic in shape and albite forms small prismatic pheno crysts aligned in a subparallel texture. lamprophyre a lamprophyre dyke cuts the pink-grey grano syenite at loc. 27 (fig. 1) in the southeastern part of the body. the rock has dark green to black colour and a fine-grained texture with ca. 20 modal % of large flaky biotite. the matrix consists of talc and carbonate aggregates (some are prob ably after olivine), zeolitized glass and small flakes of biotite. the mafic minerals occupy ca. 3c-40 modal % of the rock and the rest is mainly dusty feldspars. accessories are apatite and quartz. the modal and chemical compositions of the rock are that of a felsic monchiquite. this rock is similar to the late paleozoic lamprophyres from other parts of svalbard, such as the monchiquite and comptonite from krosspynten, on the western side of austfjorden, a comptonite from inner 74 a . m . teben’kou et al. wahlenbergfjorden, central nordaustlandet (lauritzen & ohta 1984; kovalyova & teben’kov 1986), and a lamprophyre on the southern side of ragnarbreen, n e petuniabukta, recently found by the present authors. these rocks do not seem t o be genetically related to the late caledonian granitoid rocks, but are the members of the late paleozoic platform magmatic. activity. sequence of emplacement the following successive emplacement stages have been deduced from the occurrence of the melanozomes and intrusive relationships among various types of rocks in the newtontoppen grani toid body: 1. incorporation of the melanozomes at depth, as inclusions in the dark grey granosyenites, 2. emplacement of the dark grey granos yenites, 3. emplacement of the pink-grey granosy enites, pink quartz monzonites and grey granites to form main part of the body, 4. a small intrusion of the granosyenite with aligned k-feldspar phenocrysts in the south eastern part of the body, 5. intrusion of aplites, pegmatites and quartz feldspar porphyry. petrochemistry major and trace element compositions of the newtontoppen granitoid rocks are given in tables 1 and 2. porphyritic and hypidiomorphic textures of the constituent minerals in all rocks indicate a mag matic crystallisation process. the normative q ab-or diagram (fig. 2) shows that the aplites, the grey granites and the quartz-feldspar porphyry plot near the eutectic valley of relatively high h 2 0 pressure, while the melanozomes and dark-grey granosyenites have the highest o r ratios, but with larger amounts of mafic minerals than of common granites. all other rocks plot between these two groups of rock types. the acf ratios (not shown in this article) show that two aplites and a quartz-feldspar porphyry plot in the muscovite-biotite plagioclase field, while all other rocks are in the biotite-hornblende plagioclase field, conformable with the observed assemblages. the present rocks are projected in a field of slightly lower total iron than common calc-alka line rocks (ringwood 1974) on the afm diagram (fig. 3). the alkali-lime index is difficult to esti mate, due to a flat trend of the total alkalis, but it is estimated t o be between 56 and 47, which is in the alkali-calcic to alkalic rock series (fig. 4). the roughly constant amount of total alkalis in the whole range of sioz is remarkable, unlike a positive trend normal for magmatic rocks. four grey granosyenites, three melanozome-dark grey granosyenites and the granosyenite with aligned k-feldspar are just in the alkalic rock field (irvine & baragar 1971), while the rest are in the sub alkalic field (fig. 4). o n the cation oxides vs. s i 0 2 diagrams, feo* (= total feo), mgo and n a 2 0 (fig. 5) and cao (fig. 4) show smooth curves in the range of sioz more than 63 wt 70 and these indicate a series of magmatic crystallisation. the same oxides show consistent trend, but have some deviations in the rocks with sioz less than 63 wt %; these rocks are melanozomes, dark-grey granosyenites and grey granosyenites. these deviations are due to mafic components and seem t o reflect initial dif ferences of protolith compositions or different temperatures of anatectic melting at depth. these rocks plot away from the eutectic valley in fig. 2. very large deviations of a1203 and k 2 0 in the low sio, range reflect modal differences of k feldspar and biotite. the k 2 0 contents are anom alously high in the rocks with sioz less than 65% and this can be explained by later k-feldspar addition t o the rocks formed in an earlier stage, as mentioned in the petrography. conversion of the mafic minerals into chlorite is rare, indicating a less hydrous condition during the later stages of the consolidation. according t o hjelle (1966), the k-feldspar phenocrysts from these granitoids have 20-26 mole % of a b contents, including exsolved perthites, but excluding inclusions. this indicates that the k-feldspar crystallisation occurred at not as low a temperature as the hydro thermal stage. the newtontoppen granitoid rocks are not the m-type on the k 2 0 n a 2 0 c a 0 diagram (not shown in this article, white 1979; pitcher 1979, 1983a, 1983b; whalen 1985), and not the a-type on the cao + mgo/total feo vs. sioz and the g a vs. a1203 diagrams (not shown, whalen et al. 1982; collins et al. 1982). then, the rocks were examined on the nazo vs. k 2 0 diagram (fig. 6) which shows that all melanozomes, dark-grey newtontoppen grunitoid rocks, their geology, chemistry and rb-sr age 75 1 6 . 1 4 . 13' 12 '19 7 %16 j 5 2 06 ' p 1 7 a1203 15 13 10 8 + 4. 0 2 0 11+ + 2 i 3 12 218 + 14 a a5 , feo* 2 l , el *a 0 i aol na2o 0 3 . 0 fig. 5. cation oxides vs. s i 0 2 diagrams, in weight percent granosyenites and grey granosyenites are of the s-type, while the other rocks plot around the boundary between the sand i-type (chappel & white 1974; white & chappel 1977, 1983). the r y 6 . 51 oj+ + i i i 1 . . . i . . . 1 2 3 4 nan0 fig. 6. k 2 0 n a 2 0 diagram, in weight percent. the s and i type division: white & chappel (1977). majority of the grey granites plot in the i-type field. normative corundum values are higher than 1 in the aplites and the quartz-feldspar porphyry, while four granites and pink granosyenites have normative corundum less than 1 and fourteen others have 0. this also shows that the majority of the rocks are around the boundary composition between the two granite types (white & chappel 1983). the s-type nature of the melanozomes, dark grey granosyenites and grey granosyenites suggests an anatectic origin. their higher modal mafic constituents and occurrence of clino pyroxene in these rocks infer contamination from residual materials of the partial melting. the other rocks are the products of fractional crys tallisation of the anatectic magma, the process of which was terminated around the eutectic valley to form the granites, aplites, and quartz-feldspar porphyry, thus they show i-type chemical natures. the existence of hornblende and the lack of mus covite, except for secondary sericite and those in the aplites and pegmatites, suggest that most of the rocks belong to the magnetite series of ishi hara (1977). the analysed trace elements (table 2) are nor malised to the average i-type granite (taylor & mclennan 1985) in spider diagrams (figs. 7a, 7b and 7c). these diagrams show that the present granitoid rocks are evidently different from i-type granites and have similar patterns to the average s-type granite (taylor & mclennan 1985), with more pronounced characteristics of high zr, cr and ni, and low y , ti and v. large deviations of alkali and alkali-earth trace elements reflect the modal difference of feldspars. high concen 76 a . m . teben'kov et al. 800 k 500 n cij 300 200 trations of cr and ni infer that their protoliths may have some basic components and that the supposed anatectic melting occurred at a rela tively high temperature. this is conformable with relatively high mgo contents in the melanozomes and dark grey granosyenites (fig. s ) , which may contain some residuals of inferred partial melting, e.g. clinopyroxene. blank tests of the cr and ni analyses to check the contamination during preparation of samples have not been performed; however, the same laboratory procedures have been applied for many samples from various localities without any recognisable contami nation. two groups are recognisable on the y-mgo a 0 c + x+ ycx. f + + + 0 a + x a + x ae a a a a 1 2 3 4 5 6 7 mgo w t % 1 fig. 7. spider diagrams of the trace elements, normalised to the average i-type granite (taylor & mclennan 1985). average s type granite (taylor & mclennan 1985) is shown by the dotted line in all three diagrams. a. between solid lines: melanozomes and dark grey grano syenites (5 samples); broken lines: pink-grey granosyenites (2 samples). b. between solid lines: grey granites (4 samples); broken lines: aplites (2 samples). c. between solid lines: pink quartz monzonites (4 samples); broken line: granosyenite with aligned k-feldspar; chained line: quartz-feldspar porphyry. 3000 2000' a 'aa 1000 b x + + + +a + k 500 a d 300 0 0 ~ p 2ool a 1 2 3 4 100 " . @ ' cao wt % fig. 8. some trace and major element ratios. symbols are the same as fig. 2. a . y-mgo diagram. b. ba-cao diagram. c. sr-cao diagram. newtontoppen granitoid rocks, their geology, chemistry and rb-sr age 77 diagram (fig. 8a). one is a very weak positive relation of y with mgo in the high mgo range, which corresponds to the low sio? range of fig. 5. the other group is in the low mgo range and shows large deviations without any recognisable trend. as these elements are mostly in the mafic constituents, this reflects the difference of modal mafic minerals which, in turn, depends on the amount of k-feldspar. in the present samples, rocks with large amounts of feldspar have small amounts of mafic. y-ti02, cr and ni vs mgo (not shown) show similar groups as the y-mgo diagram. two similar trends can be seen in the ba and sr vs. cao diagrams (figs. 8b and 8c). negative relations in the high cao range are shown by the melanozomes, dark-grey granosyenites, while the pink-grey granosyenites in these diagrams and the other rocks show positive trends. the positive trends are caused by a decrease of plagioclase during crystallisation fractionation, while the negative trends in the high cao range show no relation with the magmatic process. o n the zr-mgo and sc-ti02 diagrams (not shown in this article), the two groups are also recognised; the melanozomes, dark-grey grano syenites and the pink-grey granosyenites in the high mgo and high t i 0 2 fields, and the rest of the rocks in the low fields. both groups have positive relations in these diagrams, but with dif ferent ratios. these two groups roughly coincide with those showing different degrees of deviation in the a1203 and kzo variation diagrams (fig. 5) and represent the different formation processes; an anatectic partial melting containing some pro tolith residuals in the early stage, e.g. with less than 63% s i 0 2 , and an eutectic crystallisation in the later stage. isotopic age determination previous dating all three granitoid bodies of the chydeniusbreen granitoid suite intrude within the lomfjorden supergroup producing thermal aureoles, and the raudberget granitoid is covered unconformably by carboniferous strata. the rocks have not suf fered any orogenic deformation; they are there fore later than the major caledonian orogenic events which probably ended in the late silurian (gee & page 1994). the k-ar whole rock and rb-sr biotite ages, ca. 400 ma, (hamilton et al. 1962) suggest cooling in early devonian time. a new rb-sr whole rock-apatite isochron dating, using 15 samples and an u-pb zircon dating with four samples has been attempted. rb-sr dating analytical procedure. thirteen whole rocks and two apatites were analysed for their rb and sr contents and sr isotope compositions. the samples were dissolved in h f and hc104 and the residue was dissolved in hci and put in a column with resin dowex 50 x 3 (200-400 mesh). rb and sr contents were determined by isotope dilution and mass-spectrometry. all isotope compositions were measured with the mi 1201-t mass-spec trometer at the geochemical laboratory of the kola science centre at apatity, russia. the rb and sr blanks are 2 ng and 8 ng, respectively. the uncertainty of the 87rb/s6sr ratio is assumed to be 1.5% and that of the s7sr/86sr to be 0.04%. the age calculation has been carried out after the program of ludwig (1991). results and interpretation. -the results of r b and sr isotope analyses are given in table 3 and shown in fig. 9. the best-fit line includes seven samples: one apatite (28-2-ap, which has a smaller "rb/ s6sr ratio than 13-8-ap), two aplites, two grano syenites with aligned k-feldspar phenocrysts, one quartz monzonite and one melanozome. these make a seven-point isochron (msdw = 2.59) which yields 432 2 loma, with a high 87sr/86sr initial ratio, 0.715 4 3, indicating a crustal origin of the rocks. seven other samples (two quartz monzonites, a melanozome, a pink-grey grano syenite, a granosyenite with aligned k-feldspar, a quartz porphyry and an apatite; 13-8-ap) are scattered above and one quartz monzonite below the isochron. no special reason for the deviation has been found, but it may be due to the het erogeneity of these rocks. the obtained age is considered as the crystallisation age of the grani toid rocks. this age is ca. 30 ma older than the previously reported k-ar whole rock and rb-sr biotite ages (hamilton et al. 1962) which show the cooling time. the t(dm) calculated after the model-1 of bal asov et al. (1992), with the parameters of present day s7rb/86sr = 0.062576 and 87sr/86sr = 0.7032 of the e(enriched)-type, using the average of the 78 a . m. teben'kou et al. 0.058 n n in 0.062 0.054 table 3. rb and sr isotope analyses. the first numbers in the first column are the locality nos. in fig. 1. rb and sr of the apatites were not measured. loc. n o . kb ppm sr ppm 87rb/86sr 87sr/a6sr 360 1-1 141.3 1-2 318.4 1-5 299.8 5-1 342.8 8-1 310.9 9-1 276.3 13-8 249.7 15-1 312.0 19-1 261.6 201 323.4 23-3 306.0 28-2 257.3 34-1 253.9 13-8-ap 28-2-ap 405.5 449.4 312.6 678.8 532.9 752.0 546.1 476.1 346.6 520.8 76.4 696.5 637.9 1.154 1.850 2.482 1.232 1.590 1.060 1.386 1.977 2.236 1.839 11.590 1.067 1.042 0.015 0.005 0.7309 0.7278 0.7320 0.7256 0.7255 0.7232 0.7238 0.7278 0.7277 0.7266 0.7867 0.7216 0.7223 0.7165 0.7155 seven data points of the isochron, yielded a late mesoproterozoic source age of ca. 1050 ma. t(ur) calculation after mcculloch & chappell (1982), using the parameters of present day 87rb/86sr = 0.0827 and 87sr/86sr = 0.7045, gave an age of ca. 730 ma. these may suggest a grenvillian pro tolith, derived from a mantle source, which would be the first indication of the grenvillian event in ny friesland. however, these model ages could also be the results of mixing of older crustal rocks and juvenile mantle materials. u-pb zircon dating u-pb isotopic data of zircon were obtained from four samples by conventional dissolution method (table 4). the analytical method is the same as that described in barashov et al. (1993). the isotopic results are strongly scattered and do not fit any single discordia. however, sample 13-8 plots near the concordia at around 420 ma (fig. 10 and table 4), which is conformable with the rb-sr age. conclusions new names for the chydeniusbreen granitoid suite and its three separate bodies are introduced, based on recent mapping. the granitoid rocks intruded into the metasediments of the lomfjor den supergroup, causing thermal effects, and are covered unconformably by carboniferous sedi i ' i ' i 432 + i-1 0 ma mswd = 2.59 isr87186 = 0.71 5 + 1-3 t(dm) = 1,056 ma 0 2 4 6 8 1 0 1 2 87rbi86sr 0.70 r g . 9. rb-sr isotope ratios. the first numbers: locality numbers shown in fig. 1. -ap = apatite; open square = included in the best-fit line; cross = excluded. 1 0.074 0.070 2 r 0.066 . 207pb / 235u fig. 10. u-pb isotope ratios. the first numbers are locality numbers shown in fig. 1. ments. the shape of the newtontoppen granitoid body is suggested to be an asymmetric lopolith or a harpolith-like body. the three bodies are located near the boundaries of different litho logies in the surrounding metasediment successions, suggesting some structural control on their emplacement positions. the rocks of the newtontoppen granitoids are mainly granite and granosyenite in composition and have the chemical characteristics of the alkali calcic t o alkalic series. they have transitional chemical characteristics between sand i-type. magmatic crystallisation is clear from their newtontoppen granitoid rocks, their geology, chemistry und rb-sr age 79 textures, and the granites and aplitic dyke rocks have near eutectic compositions. the variation of sioz-rich lithologies resulted from the magmatic differentiation of anatectic melts. later k-feld spar introduction modified the rocks formed in earlier stages. the rocks with sioz less than 63 wt % ; the melanozomes, dark-grey granosyenites and grey granosyenites, have relatively large vari ations in major cation oxides and trace element contents and are considered t o be anatectic prod ucts from various protoliths under relatively high temperature conditions. a new age determination by the rb-sr whole rock-apatite isochron method gives an early sil urian (tucker & mckerrow 1995) age of 432 2 loma, ca. 30ma older than the previous k-ar whole rock and rb-sr biotite ages. the difference of these two ages may be considered as the cooling period of the body. this age is within the error range of that of the hor nemantoppen granite, the largest caledonian granite body in northwestern spitsbergen, 414 2 10 ma rb-sr whole rock (hjelle 1979). the high s7sr/86sr initial ratio, 0.715, supports a cru stal anatectic origin of the granitoid rocks. one of the u-pb analyses suggest a similar age to the rb-sr age. acknowledgements. the authors are grateful t o a. mccann for improvement of the language. many constructive comments by two anonymous referees are very much appreciated. references backlund, h. 1908: observations dans le spitzberg central. miss. sci. pour la mesure d’un arc de meridien au spitzberg entrepr. en 1899-1901 sous les auspice des gouvernrnents r u s e et suedois. miss. russe. 2. sec. 9-b. geologie 2. 28 pp. st. petersburg. balashov. yu. a., mitrofanov,f. p. & balagansky,v. v. 1992: new geochronological data on archean rocks of the kola peninsula. pp. 23-34 in correlation of precambrian for mations of the koia-karellan region and finland. (balashov, yu. a . = engl. transcription of balasov, ju. a , ) . balashov, yu. a , , larionov, a . n., gannibal, l. f., sirotkin, a. n., teben’kov, a . m., ryungenen, g. i. & ohta, y . 1993: an early proterozoic u-pb zircon age from an eskolabreen formation gneiss in southern ny friesland, spitsbergen. polar research 12, 147-152. (balashov, yu. a . = engl. transcription of balasov, ju. a,). chappel, b . w . & white, a. j. r. 1974: two contrasting granite types. pacific geology 8, 173-174. collins, w. j . , beams, s. d . , white, a . j. r. & chappel, b. w. 1982: nature and origin of a-type granites with particular reference t o southeastern australia. contributiom fur min eraiogy and petrology 80, 189-200. 80 a . m. teben’kou et al. drdsche, r. von. 1874: petrographisch-geologische beob achtungen an der westkiisten spitzbergens. tscherm. min. mitt. 3 , 181-198, 261-268, wien. garwood, e. .i. 1899: additional notes on the glacial pheno mena of spitsbergen. q. j. geol. sac. lon. 5 5 , 681-691. gee, d. g . & page, l. m. 1994 calcdonian terrane assembly on svalbard: new evidence from ar/ar dating in ny fries land. a m . j. sci. 294, 116c1186. hamilton, e. i . , harland, w. b. & miller, j . a . 1962: isotopic ages from some spitsbergen rocks. nature 195, 1191-1192. harland, w. b . 1959: the caledonian sequence in ny friesland, spitshergcn. q. j. geol. sac. lon. 114(3), 307-342. hjelle, a . 1966: the composition of some granitic rocks from spitsbergen. norsk polarinst. arbok 1965, 7-29. hjelle, a . 1979: aspects of the geology of northwest spits bergen. norsk polarinst. skr. nr. 167, 37-62. irvine, t. n. & baragar, w. r . a . 1971: a guide to the classification of the common volcanic rocks. can. j. earth sci. 8 , 523-548. ishihara, s . 1977: the magnetite-scries and ilmenite-series granitic rocks. mining geology 27, 293-305. kovalyova, g. a . & teben’kov, a . m . 1986: pozdne kaledonskie lamprofyry spicbergena (post-caledonian lam prophyres in spitsbergen). pp. 118-124 in geologija osadocnogo eechla spicbergena, leningrad, sevmorgeol ogija. krasil’seikov, a. a . 1969: kaledonskie intruzii archipelaga spicbergen (caledonian intrusions in spitsbergen). pp. 62 68 in uchenye zapiski, vol. 16, leningrad, niiga. krasil’seikov, a. a. 1979: stratigraphy and tectonics of the precambrian of svalbard. norsk polarinst. skr. 167, 73-79. lauritzen, 0. & ohta, y. 1984: geological map svalbard 1 : 500,000, sheet 4-g, nordaustlandet. norsk polarinst. skr. nr. 154d . ludwig, k. r. 1991: isoplot a plotting and regression program for isotope data, version 2-56, u . s . g . s . open file report 91-445. mcculloch, m. t. & chapell, b . w. 1982: nd isotopic charac teristics of sand i-type granites. earth planet. sci. len. 5 8 , 51-64. nathorst, a. g . 1910: beitrage zur geologie der baren-insel, spitzhergens und des konig karls landes. bull. geol. inst. upsala 10, 26 1-4 16. nordenskiold, a . e. 1875: redogorelse f o r den svenska pol arexpeditionen i r 1872-1873. bihh. k . suenska vir.-akad. handl. 2(18). 132 pp. oddel, n. e. 1927: preliminary notes o n the geology of the eastern parts of central spitsbergen: with special reference to the problem of the hecla hoek formation. q . j. geol. sac. lo& 8 3 ( 4 ) , 147-162. pitcher, w. s . 1979: comments on the geological environments of granites. pp. 1-8 in atherton, m. p. & turncy. j . (eds.): origin ofgranite batholith. geochemicaleuidence. shiva publ. ltd. pitcher, w. s. 1983a: granite types and tectonic environment. pp. 19-40 in hsu, k. (ed.): mountain building processes. academic press, london. pitcher, w. s . 1983h: granite; typology, geological environ ments and melting relations. pp. 277-285 in atherton, m . b . & gribble, c . d. (eds.): migmarites, melting and meta morphism. shiva publ. ltd. ringwood, a . e. 1974: the petrological evolution of island-arc systems. j . geol. sac. land. 130, 185204. strecheisen, a . 1976: to each plutonic rock its proper name. earth sci. reviews 12, 1-33. taylor, s. r . & mclennan, s. m. 1985: the continental crust: its composirion and euolution. blackwell sci. puhl., london. tucker, r . d . & mckerrow, w. s. 1995: early paleozoic chronology: a review in light of new u-ph zircon ages from newfoundland and britain. can. j. earth sci. 32, 368-379. tyrrell, g . w. 1922: the pre-devonian basement complex of central spitsbergen. trans. roy sac. edinb. 53, parr 1 , ( l o ) , whalen, j. b. 1985: geochemistry of an island-arc plutonic suite: the uasilau-yau yau intrusive complex, new britain, png. j. petrol. 2 6 , 603-632. whalen, j . b . , currie, k. l. & chappel, b. w. 1982: a-type granites: descriptive and geochemical data. geol. suru. can. open file, 1411. white, a . j. r . 1979: sources of granitic magmas. geol. sac. a m . absf. prog. 11, 539. white, a . j . r. & chappel, b. w. 1977: ultrametamorphism and granitoid gneisses. tecronophysics 43, 7-22. white, a . j . r & chappel, b. w. 1983: granitoid types and their distribution in the lachlan fold belt, southeastern australia. geol. sac. a m . mem. 159, 21-34. 312 pp. 209-229. no job name stable isotope food-web analysis and mercury biomagnification in polar bears (ursus maritimus)por_114 443..454 travis w. horton,1 joel d. blum,2 zhouqing xie,2 michael hren3 & c. page chamberlain4 1 department of geological sciences, university of canterbury, private bag 4800, christchurch 8140, new zealand 2 department of geological sciences, university of michigan, ann arbor, mi 48109-1005, usa 3 geology and geophysics department, yale university, p.o. box 208109, new haven, ct 06520-8109, usa 4 geological and environmental science department, stanford university, stanford, ca 94305-2115, usa abstract mercury (hg) biomagnification occurs in many ecosystems, resulting in a greater potential for toxicological effects in higher-level trophic feeders. however, hg transport pathways through different food-web channels are not well known, particularly in high-latitude systems affected by the atmospheric hg deposition associated with snow and ice. here, we report on stable carbon and nitrogen isotope ratios, and hg concentrations, determined for 26, late 19th and early 20th century, polar bear (ursus maritimus) hair specimens, collected from catalogued museum collections. these data elucidate relationships between the high-latitude marine food-web structure and hg concentrations in polar bears. the carbon isotope compositions of polar bear hairs suggest that polar bears derive nutrition from coupled food-web channels, based in pelagic and sympagic primary producers, whereas the nitrogen isotope compositions indicate that polar bears occupy > fourth-level trophic positions. our results show a positive correlation between polar bear hair hg concentrations and d15n. interpretation of the stable isotope data in combination with hg concentrations tentatively suggests that polar bears participating in predominantly pelagic food webs exhibit higher mercury concentrations than polar bears participating in predominantly sympagic food webs. keywords arctic; food webs; pelagic; polar bears; stable isotopes; sympagic. correspondence travis w. horton, department of geological sciences, university of canterbury, private bag 4800, christchurch 8140, new zealand. e-mail: travis.horton@canterbury.ac.nz doi:10.1111/j.1751-8369.2009.00114.x the warming of the arctic is predicted to significantly reduce arctic sea ice (overpeck et al. 2005), to impact marine food webs and to potentially threaten extant polar bear (ursus maritimus) populations, because of the loss of seal hunting habitat (hassol 2004). the atmospheric deposition of high levels of mercury (hg) during the arctic springtime (ariya et al. 2004) may pose an additional threat to these top predators. despite many valuable contributions to our understanding of trophic structure and hg cycling in arctic marine systems (braune et al. 2005), the relationships between food-web structure and hg transport pathways through arctic food chains represent an understudied component of the highlatitude mercury cycle (bradstreet & cross 1982; atwell et al. 1998; lu et al. 2001; fitzgerald et al. 2005; outridge, hobson et al. 2005). for example, a correlation was demonstrated between trophic position (determined from changes in d15n values between predator and prey) and hg concentration in the muscle tissues of marine fauna collected between 1988 and 1990 in canada’s lancaster sound ecosystem (atwell et al. 1998). however, this correlation excluded polar bears. a more recent study shows a similar correlation that includes polar bears (dehn et al. 2006). however, this trend is equivocal, as it is based on d15n values determined on muscle tissue, and total hg concentrations determined on liver tissue. another study finds that mercury is biomagnified between polar bear and seal livers, but not between polar bear and seal muscle (woshner et al. 2001). the lack of clear evidence for or against hg biomagnification in polar bear tissues raises questions about the ecological, biological and physiological processes, conditions and behaviours that influence the fate and transport of hg through highlatitude food webs. recent studies suggest that high-latitude ecosystems have a heightened potential for hg toxicity as a result of polar research 28 2009 443–454 © 2009 the authors 443 mailto:horton@canterbury.ac.nz the net deposition of ca. 300 tonnes of atmospheric hg in the arctic each year, primarily occuring during spring atmospheric hg-depletion events (ariya et al. 2004). several investigations further indicate that the net deposition of hg in high-latitude environments has increased during the last century. a study of hg in greenlandic polar bear hairs collected between 1892 and 2001 showed very little change in hg concentration up to about 1950, with a large increase in more recent times, presumably as a result of the increased anthropogenic inputs of hg to the atmosphere (dietz, riget, born et al. 2006). this is generally consistent with records of atmospheric hg deposition in the northern hemisphere in glacial ice cores (schuster et al. 2002) and lake sediments (fitzgerald et al. 2005; outridge, stern et al. 2005), which exhibit large increases in hg deposition between ca. 1950 and the present. given these trends in hg deposition, it is important to assess the ecological conditions of hg transport through high-latitude food webs. in this study, we determined the stable carbon and nitrogen isotopic compositions, and hg concentrations, in 26 polar bear hair specimens collected from throughout the arctic prior to 1950. our primary goal was to investigate the influence of trophic position and food-web structure on hg concentrations in polar bears from the time period prior to the most significant anthropogenic increases in atmospheric hg deposition, and prior to the impact of modern climate change on sea-ice extent in the arctic. this study provides a baseline from which current and future effects of hg deposition and climate change on polar bear hg exposure can be referenced. materials and methods hair samples from 26 polar bears were obtained from the national museum of natural history in washington, d.c., the harvard museum of comparative zoology in cambridge, ma, and the american museum of natural history in new york, for stable isotope ratio and hg concentration analyses. museum staff cut 50–100-mg guard hair specimens from the ventral section of the catalogued museum polar bear pelts. specimen collection dates range from 1881 to 1946, and the collection locations span the arctic basin (fig. 1; table 1). of the 26 samples collected, all 26 have specific collection dates, but only 14 have specific collection locations recorded in the various museum catalogues. stable isotope analyses were performed at the department of geological and environmental sciences, stanford university. all samples were washed in a weak (<0.01%) sodium hydroxide-based detergent, rinsed three times in deionized water and were then allowed to dry in air overnight prior to analysis. isotope ratios for n and c are presented in delta notation, with per mille (‰) units relative to isotopic reference standards, where d = 1000[(rsample/rstandard) 1], and r = 15n/14n and 13c/ 12c, for d15n and d13c, respectively. the isotopic reference standards are atmospheric n2 for d15n, and viennapeedee belemnite for d13c. isotopic measurements were made on ca. 0.75-mg hair samples using an ecs 4010 elemental analyzer (costech analytical technologies, valencia, ca, usa) operating with continuous flow to a finnigan delta plus xl mass spectrometer (thermo scientific, waltham, ma, usa). the precision of the isotopic analyses was determined to be �0.2‰ for both d15n and d13c, based on replicate analyses of acetanilide, ammoniumsulfate, sodiumnitrate, glycine, polyethylene foil, geophysical gel and nbs-22 reference materials. the hg concentration analyses were performed in the department of geological sciences, university of michigan. prior to analysis ca. 1-mg samples were shaken for 3 h in 1% rbs-35 detergent (thermo scientific), and rinsed three times in deionized water to clean the hair of possible external contamination. samples were then dried overnight in a clean box with desiccant, and weighed into teflon digestion vessels. concentrated hno3 and h2o2 were added to the vessels, and samples were completely digested in a closed-system microwave digestion apparatus. after cooling in a water bath, the vessels were opened and solutions were diluted with deionized water. certified reference materials (crms) and reagent blanks were digested with each batch of eight samples, and most samples were digested in duplicate for quality control. samples were analysed for total hg by cold-vapour atomic absorption spectroscopy (l = 253.7 nm), using an automated ma-2 hg analyser (nippon instruments, college station, tx, usa). the hg2+ in solution was reduced by sncl2 to hg0, concentrated on a gold trap and then released by heating for analysis. concentration curves spanning the analytical range were established each day, with coefficient of determination (r2) values of 0.999 or better, and check standards and replicate samples were run after every eighth sample. the limit of detection was 0.2 ng l-1 (well below all sample solution concentrations) and the analytical uncertainty was �5%, as verified by analyses of crm-397 (bureau communautaire de références [bcr] human hair; quevauviller et al. 1992) and replicate analyses. results the stable isotopic results (fig. 2; table 1) show a greater range in polar bear hair d13c (from -17.5‰ to -13.0‰) and d15n values (from 18.2‰ to 23.5‰) than are found in the published polar bear muscle analyses (ramsay & mercury biomagnification in polar bears t.w. horton et al. polar research 28 2009 443–454 © 2009 the authors444 hobson 1991; hobson & welch 1992; atwell et al. 1998). the mean d13c value is -15.3‰ (1.1‰ sd) and the mean d15n value is 20.5‰ (1.4‰ sd) for the 26 specimens analysed. the mean polar bear hair d15n value reported here agrees well with previously published polar bear muscle d15n values for lancaster sound, nt, canada. hobson & welch (1992) reported a mean of 21.1‰ and an sd of 0.6‰ (n = 3). atwell et al. (1998) reported a mean of 19.6‰ and an se of 0.5‰ (n = 5). however, the d13c values reported here are significantly different (one-way anova, p < 0.0001) than previously published d13c values for polar bear muscle samples collected from eskimo point, nt, canada, which range between -16.6‰ and -18.3‰ (mean -17.7‰, sd 0.2‰, n = 12; ramsay & hobson 1991), and similar samples from lancaster sound, which exhibit a mean d13c value of -18.0‰ (sd 0.6‰, n = 3; hobson & welch 1992). fig. 1 map showing the collection locations, number of specimens and year of collection, as recorded in the museum catalogues. the specific collection locations were only recorded for 14 of the 26 samples analysed. see table 1 for all of the available sample information. mercury biomagnification in polar bearst.w. horton et al. polar research 28 2009 443–454 © 2009 the authors 445 ta b le 1 p o la r b e ar h ai r d at a. c at al o g u e n u m b e r (m u se u m ) [h g ] (m g g -1 ) s ta n d ar d d e vi at io n (n ) d1 3 c (‰ ) s ta n d ar d d e vi at io n (n ) d1 5 n (‰ ) s ta n d ar d d e vi at io n (n ) c : n d at e co lle ct e d a p p ro xi m at e la ti tu d e (° n ) a p p ro xi m at e lo n g it u d e (° e) 4 2 0 6 7 (a m n h ) 0 .5 2 0 .0 1 (2 ) -1 5 .3 0 .3 (3 ) 2 1 .0 0 .2 (3 ) 3 .4 4 0 4 /0 5 /1 9 1 5 n r n r 4 2 0 6 8 (a m n h ) 0 .8 8 0 .0 5 (2 ) -1 5 .5 0 .1 (3 ) 2 1 .0 0 .2 (3 ) 3 .4 5 0 4 /0 5 /1 9 1 5 n r n r 1 5 6 0 0 (a m n h ) 1 .1 5 0 .1 5 (2 ) -1 4 .3 0 .1 (3 ) 1 8 .8 0 .3 (3 ) 3 .4 0 0 1 /0 1 /1 9 0 1 n r n r 2 8 1 0 5 (a m n h ) 1 .4 5 0 .6 5 (2 ) -1 5 .3 0 .2 (3 ) 1 9 .4 0 .4 (3 ) 3 .4 3 0 1 /0 1 /1 9 0 6 n r n r 2 2 9 9 7 (a m n h ) 1 .6 4 0 .5 7 (2 ) -1 5 .8 0 .6 (3 ) 1 8 .9 0 .5 (3 ) 3 .5 2 0 1 /0 7 /1 9 0 4 7 9 .6 5 0 .1 2 8 1 0 4 (a m n h ) 1 .8 0 0 .6 5 (2 ) -1 4 .6 0 .1 (3 ) 1 8 .2 0 .5 (3 ) 3 .4 3 0 1 /0 1 /1 9 0 6 n r n r 3 4 4 2 4 (a m n h ) 1 .8 6 0 .7 2 (4 ) -1 6 .6 0 .2 (3 ) 2 1 .8 0 .3 (3 ) 3 .4 8 1 0 /1 1 /1 9 1 1 6 9 .6 -1 2 5 .9 1 5 6 0 1 (a m n h ) 2 .0 1 0 .0 7 (2 ) -1 4 .6 0 .3 (3 ) 1 9 .5 0 .3 (3 ) 3 .4 1 0 1 /0 1 /1 9 0 1 n r n r 8 0 1 1 8 (a m n h ) 2 .3 1 0 .0 7 (2 ) -1 5 .2 0 .1 (3 ) 1 9 .0 0 .3 (3 ) 3 .4 4 1 8 /0 1 /1 9 2 7 n r n r 4 2 0 8 1 (a m n h ) 2 .9 2 0 .2 3 (2 ) -1 4 .9 0 .8 (3 ) 2 0 .6 0 .3 (3 ) 3 .3 8 0 1 /0 1 /1 9 0 1 n r n r 2 7 5 1 2 4 (n m n h ) 3 .0 5 0 .1 3 (2 ) -1 5 .5 0 .6 (2 ) 2 0 .4 0 .4 (2 ) 3 .4 0 0 6 /0 9 /1 9 4 6 7 5 -8 6 4 4 8 7 6 9 (n m n h ) 3 .1 7 0 .3 1 (2 ) -1 3 .0 0 .3 (2 ) 2 0 .1 0 .2 (2 ) 3 .3 4 1 2 /0 5 /1 9 0 9 7 0 .8 -1 6 7 .2 3 4 4 2 2 (a m n h ) 3 .4 7 0 .5 1 (2 ) -1 7 .4 0 .0 (2 ) 2 1 .3 0 .2 (2 ) 3 .4 6 3 0 /0 8 /1 9 1 0 6 9 .6 -1 2 5 .9 2 0 0 7 7 0 (n m n h ) 3 .5 3 0 .2 1 (2 ) -1 6 .4 0 .2 (2 ) 2 2 .4 0 .0 (2 ) 3 .4 5 1 2 /0 2 /1 9 1 5 7 4 .7 1 9 .8 1 4 8 8 6 (a m n h ) 3 .7 8 0 .9 2 (5 ) -1 4 .3 0 .2 (3 ) 1 9 .4 0 .7 (3 ) 3 .3 9 0 1 /1 0 1 8 9 5 n r n r 2 7 5 1 1 7 (n m n h ) 3 .9 6 0 .2 9 (2 ) -1 5 .0 0 .1 (2 ) 2 0 .2 0 .1 (2 ) 3 .4 3 2 8 /0 8 /1 9 4 6 7 3 .5 -7 8 .9 4 2 0 8 2 (a m n h ) 4 .5 5 0 .5 7 (2 ) -1 4 .2 0 .1 (3 ) 1 9 .5 0 .2 (3 ) 3 .4 0 0 1 /0 1 /1 9 0 1 n r n r 5 7 9 2 (m c z) 4 .6 9 0 .3 5 (2 ) -1 5 .0 0 .7 (3 ) 1 9 .8 0 .3 (3 ) 3 .4 0 2 1 /0 2 /1 9 0 9 5 7 .4 -1 7 0 4 2 0 8 0 (a m n h ) 5 .3 1 0 .3 9 (3 ) -1 5 .4 0 .1 (3 ) 2 1 .0 0 .2 (3 ) 3 .4 1 0 1 /0 1 /1 9 0 1 n r n r 3 4 4 2 3 (a m n h ) 5 .3 9 0 .4 1 (2 ) -1 6 .7 0 .2 (3 ) 2 1 .3 0 .4 (3 ) 3 .5 1 0 1 /0 7 /1 9 1 1 6 9 .6 -1 2 5 .9 3 4 4 2 1 (a m n h ) 6 .6 6 0 .6 3 (3 ) -1 6 .5 0 .1 (3 ) 2 1 .6 0 .7 (3 ) 3 .5 3 1 1 /1 1 /1 9 1 1 6 9 .6 -1 2 5 .9 1 5 4 2 0 7 (n m n h ) 7 .6 2 0 .4 7 (2 ) -1 6 .3 n /a (1 ) 2 3 .4 n /a (1 ) 3 .4 0 0 1 /0 2 /1 9 0 8 7 0 -1 4 6 .4 1 5 4 2 0 6 (n m n h ) 3 0 .2 7 8 .6 9 (3 ) -1 7 .5 n /a (1 ) 2 3 .5 n /a (1 ) 3 .4 3 0 1 /1 2 /1 9 0 8 7 0 -1 4 6 .4 1 9 2 5 5 (a m n h ) 3 1 .4 5 1 4 .4 2 (4 ) -1 5 .1 0 .1 (3 ) 1 9 .3 0 .4 (3 ) 3 .4 5 0 1 /0 1 /1 9 0 2 7 8 .7 -7 6 .6 1 3 9 9 9 (n m n h ) 6 4 .0 7 1 9 .2 9 (2 ) -1 5 .5 n /a (1 ) 2 2 .0 n /a (1 ) 3 .4 4 2 3 /0 3 /1 8 8 3 n r n r 1 3 3 6 1 (n m n h ) 1 9 2 2 .2 0 4 0 8 .9 7 (2 ) -1 3 .1 n /a (1 ) 1 9 .6 n /a (1 ) 3 .4 1 0 8 /1 8 8 1 * 7 1 .2 1 8 0 a b b re vi at io n s: a m n h , a m e ri ca n m u se u m o f n at u ra lh is to ry ; m c z , m u se u m o f c o m p ar at iv e zo o lo g y; n m n h , n at io n al m u se u m o f n at u ra lh is to ry ; n r , lo ca ti o n n o t re co rd e d in th e m u se u m ca ta lo g u e . *o n ly th e m o n th an d ye ar ar e lis te d in th e ca ta lo g u e . mercury biomagnification in polar bears t.w. horton et al. polar research 28 2009 443–454 © 2009 the authors446 most hair samples were analysed in triplicate for both d13c and d15n, with some samples exhibiting intraspecimen variability (reported as the sd of triplicate analyses; table 1) in excess of the reported analytical error of 0.2‰. however, the intraspecimen variability in polar bear hair isotopic compositions is approximately an order of magnitude lower than the total range in hair d13c and d15n values observed in the sample set, suggesting that the large range in isotopic compositions across all specimens is most likely to result from differences in the ecosystem conditions, such as the isotopic composition of primary producers and local food-web structure, rather than individual feeding behaviours. the total [hg] ranges between 0.52 and 7.62 mg g-1 for 22 of the 26 wild polar bear hair specimens investigated, with a mean concentration of 3.26 mg g-1 (sd 1.9 mg g-1; table 1). four specimens exhibited an anomalously high [hg] (>30 mg g-1), with high intraspecimen variability among triplicate analyses (sd > 8.69 mg g-1). although none of the museum catalogues explicitly denote information regarding preservative applications, these four samples may have been exposed to mercuric chloride (which was sometimes used as a specimen preservative in the late 1800s and early 1900s) during sampling, museum cataloguing or subsequent storage. as these four specimens are statistical outliers, being more than 13 standard deviations above the mean, we do not consider them in our [hg] data interpretations. intraspecimen [hg] variability for the 22 samples considered in our analysis range between 0.01 and 0.92 mg g-1 (reported as the standard deviation of duplicate or triplicate analyses; table 1). discussion in order to accurately interpret relationships among historic polar bear hair stable isotope and hg concentration data, similar data for other arctic marine organisms lower in the food chain is required, as both the isotopic composition and hg concentration of biologic materials depend upon trophic position, food-web structure and feeding behaviour. however, the general lack of historic (pre-1950) stable isotope and hg concentration data for most arctic marine organisms, and the limited availability of suitable specimens for such analyses, present immediate challenges to such research. in an effort to overcome these limitations, we have compiled both modern (post1980) and historic (pre-1950) data available from the literature for a variety of organisms from a variety of high-latitude locations. all previously published data is cited in the following discussion, and in the accompanying figures, where appropriate. it is important to consider the fundamental limitations that the temporal and geographic heterogeneity of the presented data impose on our interpretations. given the geographic heterogeneity of the polar bear hair data we present, all interpretations are relevant only on broad regional scales. previous research has demonstrated that complex relationships between food-web channels exist on spatial scales of less than 100 km (tamelander et al. 2006), whereas d13c values of marine invertebrates are known to vary by ca. 2–4‰ between the bering/chukchi and beaufort/arctic ocean regions (schell et al. 1998). with respect to hg, eaton & farant (1982) reported polar bear hair concentrations in the western canadian arctic (amundsen gulf) that are approximately 10 ppm higher than in the central and eastern canadian arctic, for samples collected between 1977 and 1980. specimen location data are available for only 11 of the 22 polar bear hair samples discussed below (table 1). given this low sample size, and the resultant low spatial sample density, geographic effects are beyond the scope of this study. for a comprehensive review of spatial and temporal trends in fig. 2 d15n versus d13c values for arctic faunal tissues. the open black star represents the average value for phytoplankton (as particulate organic matter); the solid black star represents the average ice algae values described in the text. the sources of data as as follows: phytoplankton (hobson & welch 1992; hobson et al. 2002; tamelander et al. 2006; tremblay et al. 2006); ice algae (hobson & welch 1992; hobson et al. 2002; campbell et al. 2005; tamelander et al. 2006; tremblay et al. 2006); sympagic amphipods (tremblay et al. 2006); invertebrates (hobson & welch 1992; hobson et al. 2002; campbell et al. 2005; tamelander et al. 2006); birds (hobson & welch 1992; hobson et al. 2002; tremblay et al. 2006); fish (hobson & welch 1992; hobson et al. 2002; kurle 2002; campbell et al. 2005; tamelander et al. 2006); marine mammals (hobson & welch 1992; muir et al. 1995; hobson et al. 1997; hobson et al. 2002; kurle 2002; campbell et al. 2005; outridge, hobson et al. 2005). all of the previously published data were determined for vertebrate muscle tissue and invertebrate whole-body homogenates. mercury biomagnification in polar bearst.w. horton et al. polar research 28 2009 443–454 © 2009 the authors 447 hg concentrations determined for various arctic marine biota, see braune et al. (2005). similarly, the temporal heterogeneity, limited sample size and lack of biophysical data (including age, collection season, sex and sexual maturity/reproductive status) in our data set precludes robust interpretation of time-dependent changes in food-web structures, hg deposition/uptake rates, biophysical effects and biomagnification trends through time. however, the data do allow us to interpret gross regional-scale relationships between food-web structure and the fate and transport of hg through a composite high-latitude food web, irrespective of space and time. as a result of these important limitations, our discussion centres on the interpretation of regional food-web structure based on the d13c and d15n data, and the relationships between the composite highlatitude food-web structure and the hg concentrations found in polar bear hair. stable isotopes the stable isotopic assessments of food-web structure are based on the enrichment of 15n and 13c in consumer tissues, relative to diet. these fractionations are more pronounced for nitrogen (d15nconsumer d15ndiet ª 2–4‰) than for carbon (d13cconsumer d13cdiet ª 0–2‰), suggesting that the nitrogen isotopic composition is directly related to the trophic position of an organism, and that the carbon isotopic composition reflects the carbon source at the base of the food web (kelly 2000). carbon the 4.4‰ range in hair d13c values reported here suggests that polar bears participate in food webs with a similarly wide range in primary producer carbon isotope compositions. previous research by hilderbrand et al. (1996) indicates that the isotopic composition of american black bear (ursus americanus) hair and muscle tissues are not significantly different when fed the same diet over a seven-month period; assuming the same relationship exists in polar bears, the significant difference between polar bear hair (this study) and muscle (ramsay & hobson 1991; hobson & welch 1992) d13c values described above, supports the interpretation that the carbon isotope composition of primary producers differs by several per mille (ca. 4–5‰)across the arctic. primary production in arctic ecosystems occurs predominantly in phytoplankton and ice algae in pelagic and sympagic environments, respectively. bradstreet & cross (1982) reported on the importance of the sympagic ice algae community to arctic food webs, and welch (1992) suggested that sympagic primary production accounts for ca. 10% of total primary production in the 98 000-km2 lancaster sound region. two recent investigations report on the carbon isotope composition of phytoplankton, as particulate organic matter, and ice algae in arctic systems, with both investigations finding that ice-associated particulate organic matter exhibits d13c values approximately 3–10‰ more positive than pelagic organic matter (tamelander et al. 2006; tremblay et al. 2006). the compiled primary producer data presented in fig. 2 further supports this finding. the previously published primary producer data presented in fig. 2 represent 76 phytoplankton (as particulate organic matter) and 43 ice algae samples collected from the barents sea (tamelander et al. 2006), north water polynya (hobson et al. 2002; tremblay et al. 2006), and barrow strait–lancaster sound (hobson & welch 1992). the carbon isotope compositions of arctic phytoplankton and ice algae are significantly different (one-way anova, p < 0.0001), with phytoplankton exhibiting an average d13c value of -22.4‰ (sd 1.1‰, n = 76), and with ice algae exhibiting an average d13c value of -18.4‰ (sd 4.2‰, n = 43). the ca. 4‰ difference in mean phytoplankton and ice algae primary producer d13c values, and 4.4‰ range in polar bear hair d13c values reported here (fig. 2), suggests polar bears derive nutrition from both of these pelagic and sympagic primary producers (i.e., phytoplankton with relatively low d13c values and ice algae with relatively high d13c values). given that sea ice represents the primary seal hunting habitat for polar bears, and that sympagic food-web channels are an important component of arctic ecosystems (bradstreet & cross 1982; welch 1992), it is not surprising that the carbon isotope composition of polar bear hairs reflects carbon fixation occurring in ice-associated environments. however, the distribution of the polar bear hair d13c values presented in fig. 2 suggests that polar bears derive nutrition from coupled pelagic and sympagic carbon sources, rather than from discrete primary production end members. alternative explanations are also possible. ice algae d13c values demonstrate a strong correlation with ice thickness in both antarctic (arrigo et al. 2003) and arctic (tremblay et al. 2006) systems, potentially explaining the high variability in the reported ice algae d13c values (e.g., tamelander et al. 2006), and ultimately contributing to the variability in polar bear hair carbon isotope compositions. additionally, benthic organisms also exhibit more positive d13c values relative to pelagic organisms (hobson et al. 2002). it is therefore not possible to differentiate between sympagic and benthic food-web components, based on carbon isotopic composition alone. relatively positive benthic organism d13c values may result from the greater uptake of organic carbon derived from 13cmercury biomagnification in polar bears t.w. horton et al. polar research 28 2009 443–454 © 2009 the authors448 enriched ice algae than of relatively 13c-depleted pelagic particulate organic matter (hobson et al. 2002). in fact, recent research suggests some arctic benthic species may preferentially consume ice algae, rather than phytoplankton, because of the higher essential fatty acid content of ice algae (mcmahon et al. 2006). given the significant difference in pelagic versus sympagic primary producer d13c values, similarities in the range of d13c values observed at all trophic positions, and the polar bears’ biological reliance on sympagic environments, we suggest that the previously undocumented range in polar bear hair d13c values reported here results from the coupling of pelagic and sympagic food-web channels in arctic ecosystems (fig. 2). nitrogen the 5.3‰ range in polar bear hair d15n values reported here (fig. 2; table 1) exceeds the range in polar bear tissue values recognized in earlier studies (hobson & welch 1992; atwell et al. 1998). arctic pelagic (6.7 � 0.6‰ sd, n = 76) and sympagic (5.6 � 1.0‰ sd, n = 43) primary producers have similar d15n values (hobson & welch 1992; hobson et al. 2002; campbell et al. 2005; tamelander et al. 2006; tremblay et al. 2006), suggesting that trophic position, rather than the source of primary production, is the main control on polar bear tissue nitrogen isotope compositions. empirical and experimental data sets indicate bear tissues show a 3.2– 4.1‰ increase in d15n values relative to diet (hobson & welch 1992; hilderbrand et al. 1996; hobson et al. 2002). assuming a nitrogen isotope fractionation of 3.8‰ per trophic level (as used in hobson et al. 2002), and an average primary producer d15n value of 6.3‰ (calculated from the primary producer data presented in fig. 2), our results indicate polar bears occupy the 4.1–5.5-level trophic positions, in good agreement with previous stable isotope-based results (hobson et al. 2002) and known trophic relationships (bradstreet & cross 1982). the polar bear hair stable isotopic data presented here advances our understanding of food-web structure in high-latitude ecosystems. as described above, the carbon isotope composition of polar bear hair suggests these top predators ultimately derive nutrition from mixed pelagic and sympagic primary producers, and associated foodweb channels, at the regional scale. given the association of polar bears with sympagic habitats, and the opportunistic feeding behaviour of the polar bears’ preferred diet (ringed seals, pusa hispida), this interpretation is intuitively plausible, if not expected. yet, the only polar bear stable isotopic data available in the literature (ramsay & hobson 1991; hobson & welch 1992; hobson et al. 2002) suggests that polar bears derive nutrition solely from pelagic food-web channels (hobson et al. 2002: fig. 1)— in contrast to the data and interpretations presented here. this is an important contribution of the current research, as recent studies suggest the arctic is a significant sink in the global hg cycle: thus, interpreting the stable isotopic data presented above, in concert with hg concentration data, provides a novel opportunity to evaluate the fate and transport of hg through high-latitude food webs and food-web channels. mercury concentrations highly elevated concentrations of hg are observed in modern arctic snow during springtime tropospheric hg-depletion events (lu et al. 2001). these events result from the rapid oxidation of globally transported gaseous elemental hg, and are believed to be exacerbated by atmospheric br and bro derived from sea-salt aerosols (lu et al. 2001; ariya et al. 2004). the accumulation of hg in high-latitude northern hemisphere systems has increased between pre-industrial and modern times, with the significant anthropogenic increase of atmospheric hg deposition occurring in the second half of the 20th century (schuster et al. 2002; fitzgerald et al. 2005; outridge, stern et al. 2005). in an effort to limit temporal effects on our interpretations, we restricted our sample set to polar bear hair specimens collected prior to 1950. our polar bear hair hg concentration data agree well with similar published data for 18 samples collected between 1910 and 1927, from the canadian arctic and hudson’s bay (eaton & farant 1982; fig. 3). elevated hg concentrations have been identified in a variety of arctic fauna across geographically and temporally heterogeneous scales, including a number of marine mammals and birds (eaton & farant 1982; wagemann et al. 1996; atwell et al. 1998; outridge, hobson et al. 2005; dietz, riget, boertmann et al. 2006; dietz, riget, born et al. 2006). previous research indicates hg biomagnification occurs in arctic food webs via uptake by primary producers and subsequent consumption by invertebrates, fish, birds and marine mammals (atwell et al. 1998). however, it is important to note that polar bears did not fit this published biomagnification trend, and that they were the only species to exhibit lower hg concentrations than their prey (atwell et al. 1998). atwell et al. suggested that this exception was most likely to have resulted from individual feeding behaviours, whereby polar bears limit their exposure to the available hg through preferential consumption of seal skin and adipose tissue (norstrom et al. 1986), both of which have been shown to exhibit lower hg concentration than muscle and organs (smith & armstrong 1975). our results for polar bear hair support this interpretation, demonstrating low mercury biomagnification in polar bearst.w. horton et al. polar research 28 2009 443–454 © 2009 the authors 449 hg concentrations (<1.0 mg g-1) in some individuals with relatively high d15n values (20–21‰). mercury biomagnification the slope of the regression of log-transformed hg concentrations versus d15n represents a quantification of the hg biomagnification power for a composite post-1980 high-latitude food web (fig. 4a). we present our polar bear hair data alongside compiled [hg] and d15n tissue data for a variety of marine fauna collected during the late 19th, early 20th and late 20th centuries (eaton & farant 1982; applequist et al. 1985; atwell et al. 1998; campbell et al. 2005; outridge, hobson et al. 2005; dietz, riget, boertmann et al. 2006). the hg biomagnification power of the composite post-1980 high-latitude food web is 0.17. this composite value is intermediate to the total hg biomagnification power of 0.20 calculated for both the lancaster sound and northwater polynya food webs (atwell et al. 1998; campbell et al. 2005), and the biomagnification power of 0.15 (i.e., a biomagnification factor of 1.40) that has been determined for the alaskan arctic (dehn et al. 2006). the 95% confidence limit of the linear regression of log[hg] versus d15n in the post-1980 samples encompasses hg biomagnification powers (i.e., regression line slopes) ranging between 0.12 and 0.22 (fig. 4a). a similar biomagnification trend is apparent in a limited pre-1950 data set (fig. 4b), including polar bears, beluga (delphinapterus leucas), black guillemots (cepphus grylle) and white-tailed eagles (haliaeetus albicilla) (eaton & farant 1982; applequist et al. 1985; outridge, hobson et al. 2005; dietz, riget, boertmann et al. 2006; this study). in contrast to previous research (atwell et al. 1998), the data presented here suggest that hg biomagnification was, and likely remains, a common process affecting most polar bears throughout the arctic. mercury transport pathways the interpretation of this biomagnification trend in the context provided by stable isotope-based assessments of food-web structure informs our understanding of the hg transport pathways in high-latitude ecosystems. based on compound-specific d13c values determined for consumers, and both sympagic and pelagic primary producers, budge et al. (2008) suggest ice algae are likely to account for 24–71% of the fatty acid material in arctic consumers near barrow, alaska. other research has found that sympagic primary production accounts for ca. 57% of total primary production in the central arctic ocean, but less than 5% in the central chukchi sea (gosselin et al. 1997). such variability in the balance between pelagic and sympagic primary production is likely to contribute to the geographic variability observed in the isotopic compositions of arctic biota (e.g., dietz et al. 1996; wagemann et al. 1996; schell et al. 1998; dehn et al. 2005), and, as a result, would also be expected to affect hg transport through sympagic versus pelagic food-web end members. the stable isotope data presented here indicate that polar bears participating in food webs dominated by pelagic organisms tend to have more positive d15n and more negative d13c values, than polar bears exploiting sympagic food-web channels (fig. 2). these pelagic polar bears exhibit the highest d15n values and hg concentrations (fig. 5b), whereas sympagic polar bears exhibit the highest d13c values, and the lowest d15n values and hg concentrations (figs. 2, 5). several ecological explanations for these relationships are possible. high-latitude pelagic food webs may be more complex than sympagic food webs, resulting in higher trophic positions (i.e., higher d15n values) and increased potential for hg biomagnification in the pelagic top predators. the fundamental difference between high-latitude seasonally ice-free and perennially ice-covered ecosystems is that seasonally ice-free ecosystems are often nutrient limited, whereas perennially ice-covered ecosystems are generally light limited (smetacek & nicol 2005). furthermore, the epipelagic copepod community composition and biomass varies with regional primary productivity (atkinson fig. 3 hg concentration versus year of sample collection for all samples with recorded collection locations and ages. the circles represent the values for polar bear hair specimens from this study; the shaded grey area shows the total range and the mean (solid line) in organic [hg] determined for 18 previously published polar bear hair specimens (eaton & farant 1982). mercury biomagnification in polar bears t.w. horton et al. polar research 28 2009 443–454 © 2009 the authors450 fig. 4 variation of log10[hg] with d15n in arctic faunal tissues for (a) previously published post-1980 specimens, and for (b) original and previously published pre-1950 specimens. the dashed line in (a) represents the composite mercury biomagnifcation trend in post-1980 specimens (data from atwell et al. 1998 and campbell et al. 2005). the grey curves correspond to the 95% confidence limit of the least-squares regression line plotted in (a). we include the post-1980 regression line and confidence limits in (b) to aid comparisons of the data. the red circles (pre-1950 polar bear hairs) in (b) represent data original to this study. the whisker plots numbered 1–4 in (b) present the range in published pre-1950 mercury concentrations for (1) black guillemot (cepphus grylle) feathers (applequist et al. 1985), (2) white-tailed eagle (haliaeetus albicilla) feathers (range in mean values of dietz, riget, boertmann et al. 2006), (3) beluga (delphinapterus leucas) muscle (range in geometric mean values of outridge, hobson et al. 2005) and (4) polar bear (ursus maritimus) hairs (eaton & farant 1982). the range in d15n values for guillemots and eagles are estimated based on the post-1980 isotopic composition of each species’ diet, and the expected nitrogen isotope fractionation of 3.8‰ per trophic level. the range in beluga d15n values corresponds to the range in d15n values from teeth, reported by outridge, stern et al. (2005). and the range in polar bear hair d15n values reported by eaton & farant (1982) is assumed to be equivalent to the range in polar bear hair d15n values reported in the current study. fig. 5 variation of [hg] with (a) d13c and (b) d15n in pre-1950 polar bear hairs. the two-tailed p value is 0.2243 and 0.0131 for the least squares regression lines presented in (a) and (b), respectively. mercury biomagnification in polar bearst.w. horton et al. polar research 28 2009 443–454 © 2009 the authors 451 1998), suggesting that fundamental differences in trophic structure between the more productive pelagic and relatively less productive sympagic systems are to be expected. direct observation of ice-associated organism stomach contents indicate that the sympagic food webs progress from ice algae, to copepods and amphipods, to arctic cod (arctogadus glacialis), to ringed seals, which are the primary food source for polar bears (bradstreet & cross 1982). more complex predator–prey relationships, particularly for organisms eating species that are low on the food chain, may exist in pelagic food webs, as suggested by the higher trophic positions (based on more positive d15n values) of pelagic amphipods compared with sympagic amphipods (tamelander et al. 2006). longer pelagic food chains would ultimately result in more than five trophic levels, and in higher hg concentrations in polar bears taking advantage of predominantly pelagic, rather than sympagic, food-web channels. high hg concentrations in polar bear hair may also result from the circumstantial consumption of prey tissues that are relatively enriched in bioavailable organic hg. polar bears primarily feed on ringed seals, the most common and best-adapted arctic seal (wagemann et al. 1996), although recent research indicates bowhead whales (balaena mysticetus) represent ca. 19% of the polar bear winter diet in the southern beaufort sea (bentzen et al. 2007). the total hg concentrations in ringed seal livers are between one and two orders of magnitude higher than the concentrations found in muscle, and about one order of magnitude higher than the concentrations found in kidneys (wagemann et al. 1996; dehn et al. 2005), and similar relationships are recognized in belugas and narwhals (monodon monoceros), both of which are less common polar bear prey species (wagemann et al. 1998). however, arctic marine mammal livers and muscle exhibit similar methylmercury (mehg) concentrations (mean concentrations of ca. 1–2 mg g-1; wagemann et al. 1998), whereas the mean values of mehg concentrations in the skin from the same individuals are in the range of 0.53–0.69 mg g-1. total hg in blubber from the same individuals range between mean values of 0.04 and 0.1 mg g-1. thus, preferential feeding on marine mammal adipose tissue may limit hg ingestion by polar bears at the same time as decreasing the 13c content of polar bear tissues, as lipid-rich diets have lower d13c values than non-lipid diets (hilderbrand et al. 1996). such feeding behaviours are likely to complicate the relationship between hg concentrations and d13c values in sympagic and pelagic polar bear hairs (fig. 5a). however, bears unable to preferentially consume adipose tissue because of environmental pressures and/or nutritional requirements may ingest significantly more hg if muscle and internal organs are consumed. perennial sea-ice may limit hg availability to sympagic food webs. a dramatic increase in the hg concentrations of snow deposited on arctic sea ice occurs between winter and spring (lu et al. 2001) as a result of arctic hg depletion events (ariya et al. 2004; douglas et al. 2008), and spring meltwaters add some of this oxidized hg to arctic ecosystems. however, the photoreduction of oxidized hg from the surface snow pack returns much of the hg deposited in snow to the atmosphere (ariya et al. 2004). this suggests that the accumulation of hg in arctic systems occurs during the spring primary productivity blooms, which are contemporaneous with halogendriven hg oxidation events and rapid meltwater transport of oxidized hg compounds into marine environments. ecosystems associated with perennial sea ice may experience less hg accumulation because of the limited transport of oxidized hg compounds through the pack ice, as well as the more pronounced photoreduction of oxidized hg compounds in surface snow (ariya et al. 2004). in contrast, epipelagic ecosystems may be more susceptible to hg bioavailability because of increased hg oxidation at higher salinities (poulain et al. 2007). conclusions our results suggest that pre-1950 polar bears derived nutrition from a combination of pelagic and sympagic food-web channels, and that hg concentrations tend to be higher in pelagic food-web participants. the variability of hg concentrations in polar bear hair specimens collected before 1950 is likely to have resulted from a combination of trophic structure, feeding behaviour and perennial seaice effects, although given the limited size and geographic heterogeneity of our data set, unrecognized spatial and temporal mechanisms are also likely. the elevated [hg] in polar bear hair in more recent times (e.g., dietz, riget, born et al. 2006) is probably related to the increased atmospheric deposition of anthropogenic hg, and may be spatially distributed, although this has not yet been adequately tested. the relationships between the regional food-web structure and hg concentrations suggested in this study should help future interpretations of hg concentrations in modern polar bears, which are also potentially affected by spatial variation in anthropogenic hg deposition, and changes in the patterns of sea-ice cover and the associated impacts on local food-web structures. acknowledgements we thank the national museum of natural history, the american museum of natural history and the museum of comparative zoology, and their staff, for providing the mercury biomagnification in polar bears t.w. horton et al. polar research 28 2009 443–454 © 2009 the authors452 requested polar bear hair specimens for analysis. this research was supported by a university of puget sound, university enrichment committee faculty research grant (r04441) to twh. we also thank three external referees for their thoughtful and detailed reviews of the initial manuscript. references applequist h., drabaek i. & asbirk s. 1985. variation in mercury content of guillemot feathers over 150 years. marine pollution bulletin 16, 244–248. ariya p.a., dastoor a.p., amyot m., schroeder w.h., barrie l., anlauf k., raofie f., ryzhkov a., davignon d., lalonde j. & steffen a. 2004. the arctic: a sink for mercury. tellus, series b: chemical and physical meteorology 56, 397–403. arrigo k.r., robinson d.h., dunbar r.b., leventer a.r. & lizotte m.p. 2003. physical control of chlorophyll a, poc, and tpn distributions in the pack ice of the ross sea, antarctica. journal of geophysical research—oceans 108, article no. 3316, doi: 10.1029/2001jc001138. atkinson a. 1998. life cycle strategies of epipelagic copepods in the southern ocean. journal of marine systems 15, 289–311. atwell l., hobson k.a. & welch h.e. 1998. biomagnification and bioaccumulation of mercury in an arctic marine food web: insights from stable nitrogen isotope analysis. canadian journal of fisheries and aquatic sciences 55, 1114–1121. bentzen t.w., follmann e.h., amstrup s.c., york g.s., wooler m.l. & o’hara t.m. 2007. variation in winter diet of southern beaufort sea polar bears inferred from stable isotope analysis. canadian journal of zoology 85, 596–608. bradstreet s.w. & cross w.e. 1982. trophic relationships at high ice edges. arctic 35, 1–12. braune b.m., outridge p.m., fisk a.t., muir d.c.g., helm p.a., hobbs k., hoekstra p.f., kuzyk z.a., kwan m., letcher r.j., lockhart w.l., norstrom r.j., stern g.a. & stirling i. 2005. persistent organic pollutants and mercury in marine biota of the canadian arctic: an overview of spatial and temporal trends. science of the total environment 351–352, 4–56. budge s.m., wooller m.j., springer a.m., iverson s.j., mcroy c.p. & divoky g.j. 2008. tracing carbon flow in an arctic marine food web using fatty acid-stable isotope analysis. oecologia 157, 117–129. campbell l.m., norstrom r.j., hobson k.a., muir d.c.g., backus s. & fisk a.t. 2005. mercury and other trace elements in a pelagic arctic marine food web (northwater polynya, baffin bay). science of the total environment 351–352, 247–263. dehn l., follmann e.h., thomas d.l., sheffield g.g., rosa c., duffy l.k. & o’hara t.m. 2006. trophic relationships in an arctic food web and implications for trace metal transfer. science of the total environment 362, 103–123. dehn l., sheffield g.g., follmann e.h., duffy l.k., thomas d.l., bratton g.r., taylor r.j. & o’hara t.m. 2005. trace elements in tissues of phocid seals harvested in the alaskan and canadian arctic: influence of age on feeding ecology. canadian journal of zoology 83, 726–746. dietz r., riget f., boertmann d., sonne c., olsen m.t., fjeldsa j., falk k., kirkegaard m., egevang c., asmucd g., wille f. & moller s. 2006. time trends of mercury in feathers of west greenland birds of prey during 1851–2003. environmental science and technology 40, 5911–5916. dietz r., riget f., born e.w., sonne c., grandjean p., kirkegaard m., olsen m.t., asmund g., renzoni a., baagøe h. & andreasen c. 2006. trends in mercury in hair of greenlandic polar bears (ursus maritimus) during 1892–2001. environmental science and technology 40, 1120–1125. dietz r., riget f. & johansen p. 1996. lead, cadmium, mercury, and selenium in greenland marine animals. science of the total environment 186, 67–93. douglas t.a., sturm m., simpson w.r., blum j.d., alvarez-aviles l., keeler g.j., perovich d.k., biswas a. & johnson k. 2008. influence of snow and ice crystal formation and accumulation on mercury deposition to the arctic. environmental science and technology 42, 1542–1551. eaton r.d.p. & farant j.p. 1982. the polar bear as a biological indicator of the environmental mercury burden. arctic 35, 422–425. fitzgerald w.f., engstrom d.r., lamborg c.h., tseng c.m., balcom p.h. & hammerschmidt c.r. 2005. modern and historic atmospheric mercury fluxes in northern alaska: global sources and arctic depletion. environmental science and technology 39, 557–568. gosselin m., levasseur m., wheeler p.a., horner r.a. & booth b.c. 1997. new measurements of phytoplankton and ice algal production in the arctic ocean. deep sea research part i 44, 1623–1644. hassol s.j. 2004. impacts of a warming arctic. cambridge, uk: cambridge university press. hilderbrand g.v., farley s.d., robbins c.t., hanley t.a., titus k. & servheen c. 1996. use of stable isotopes to determine diets of living and extinct bears. canadian journal of zoology 74, 2080–2088. hobson k.a., fisk a., karnovsky n., holst m., gagnon j.m. & fortier m. 2002. a stable isotope (d13c, d15n) model for the north water food web: implications for evaluating trophodynamics and the flow of energy and contaminants. deep sea research part ii 49, 5131–5150. hobson k.a., sease j.l., merrick r.l. & piatt j.f. 1997. investigating trophic relationships of pinnipeds in alaska and washington using stable isotope ratios of nitrogen and carbon. marine mammal science 13, 114–132. hobson k.a. & welch h.e. 1992. determination of trophic relationships within a high arctic marine food web using d13c and d15n analysis. marine ecology progress series 84, 9–18. kelly j.f. 2000. stable isotopes of carbon and in the study of avian and mammalian trophic ecology. canadian journal of zoology 78, 1–27. mercury biomagnification in polar bearst.w. horton et al. polar research 28 2009 443–454 © 2009 the authors 453 kurle c.m. 2002. stable-isotope ratios of blood components from captive northern fur seals (callorhinus ursinus) and their diet: applications for studying the foraging ecology of wild otariids. canadian journal of zoology 80, 902–909. lu j.y., schroeder w.h., barrie l.a., steften a., welch h.e., martin k., lockhart l., hunt r.v., boila g. & richter a. 2001. magnification of atmospheric mercury deposition to polar regions in springtime: the link to tropospheric ozone depletion chemistry. geophysical research letters 28, 3219–3222. mcmahon k.w., ambrose w.g. jr., johnson b.j., sun m.y., lopez g.r., clough l.m. & carroll m.l. 2006. benthic community response to ice algae and phytoplankton in ny ålesund, svalbard. marine ecology progress series 310, 1–14. muir d.c.g., segstro m.d., hobson k.a., ford c.a., stewart r.e.a. & olpinski s. 1995. can seal eating explain elevated levels of pcbs and organochlorine pesticides in walrus blubber from eastern hudson bay (canada)? environmental pollution 90, 335–348. norstrom r.j., schweinsberg r.e. & collins b.t. 1986. heavy metals and essential elements in livers of the polar bear (ursus maritimus) in the canadian arctic. science of the total environment 48, 195–212. outridge p.m., hobson k.a. & savelle j.m. 2005. changes in mercury and cadmium concentrations and the feeding behaviour of beluga (delphinapterus leucas) near somerset island, canada, during the 20th century. science of the total environment 350, 106–118. outridge p.m., stern g.a., hamilton p.b., percival j.b., mcneely r. & lockhart w.l. 2005. trace metal profiles in the varved sediment of an arctic lake. geochimica et cosmochimica acta 69, 4881–4894. overpeck j.t., sturm m., francis j.a., perovich d.k., serreze m.c., benner r., carmack e.c., chapin iii f.s., gerlach s.c., hamilton l.c., hinzman l.d., holland m., huntington h.p., key j.r., lloyd a.h., macdonald g.m., mcfadden j., noone d., prowse t.d., schlosser p. & vörösmarty c. 2005. arctic system on trajectory to new, seasonally ice-free state. eos, transactions of the american geophysical union 86, 312–313. poulain a.j., garcia e., amyot m., campbell p.g.c., raofie f. & ariya p.a. 2007. biological and chemical redox transformations of mercury in fresh and salt waters of the high arctic during spring and summer. environmental science and technology 41, 1883–1888. quevauviller p., maier e.a., vercoutere k., muntau h. & griepink b. 1992. certified reference material (crm 397) for the quality control of trace element analysis of human hair. fresenius’ journal of analytical chemistry 343, 335–338. ramsay m.a. & hobson k.a. 1991. polar bears make little use of terrestrial food webs: evidence from stable-carbon isotope analysis. oecologia 86, 598–600. schell d.m., barnett b.a. & vinette k.a. 1998. carbon and nitrogen isotope ratios in zooplankton of the bering, chukchi and beaufort seas. marine ecology progress series 162, 11–23. schuster p.f., krabbenhoft d.p., naftz d.l., cecil l.d., olson m.l., dewild j.f., susong d.d., green j.r. & abbott m.l. 2002. atmospheric mercury deposition during the last 270 years: a glacial ice core record of natural and anthropogenic sources. environmental science and technology 36, 2303–2310. smetacek v. & nicol s. 2005. polar ocean ecosystems in a changing world. nature 437, 362–368. smith t.g. & armstrong f.a.j. 1975. mercury in seals, terrestrial carnivores, and principal food items of the inuit, from holman, n.w.t. journal of the fisheries research board of canada 32, 795–801. tamelander t., renaud p.e., hop h., carroll m.l., ambrose w.g. jr. & hobson k.a. 2006. trophic relationships and pelagic–benthic coupling during summer in the barents sea marginal ice zone, revealed by stable carbon and nitrogen isotope measurements. marine ecology progress series 310, 33–46. tremblay j.e., michel c., hobson k.a., gosselin m. & price n.m. 2006. bloom dynamics in early opening waters of the arctic ocean. limnology and oceanography 51, 900–912. wagemann r., innes s. & richard p.r. 1996. overview and regional and temporal differences of heavy metals in arctic whales and ringed seals in the canadian arctic. science of the total environment 186, 41–66. wagemann r., trebacz e., boila g. & lockhart w.l. 1998. methylmercury and total mercury in tissue of arctic marine mammals. science of the total environment 218, 19–31. welch h.e. 1992. energy flow through the marine ecosystem of the lancaster sound region, arctic canada. arctic 45, 343–357. woshner v.m., o’hara t.m., bratton g.r. & beasley v.r. 2001. concentrations and interactions of selected essential and non-essential elements in ringed seals and polar bears of arctic alaska. journal of wildlife diseases 37, 711–721. mercury biomagnification in polar bears t.w. horton et al. polar research 28 2009 443–454 © 2009 the authors454 no job name komi reindeer herding: the effects of socialist and post-socialist change on mobility and land usepor_108 282..297 mark j. dwyer1 & kirill v. istomin2 1 department of geography, university of cambridge, downing place, cambridge, cb2 3en, uk 2 max planck institute for social anthropology, advokatenweg 36, de-06114 halle/saale, germany abstract this paper contributes to the discussion concerning the way in which soviet state policies have influenced the lives, social organization, economy and culture of a group of indigenous komi reindeer herders of northern russia: its main focus is to explain how these policies have changed the herders’ patterns of migration and land use. extensive anthropological fieldwork—to determine current and past herding practices—was carried out and archives were thoroughly investigated to document land use changes in relation to state reindeer herding policies. it was found that compared with those of several decades ago, the migration routes are now much shorter, as the herders have abandoned large areas of winter pastures located in the southernmost part of their herding territory. this “abandonment” phenomenon is endemic amongst reindeer herders generally, throughout the komi republic. whereas the reasons for the abandonment of winter pastures are diverse, they can be attributed mostly to the state sedentarization policy, which has modified the family structures of herders, and the continuing decreases in state subsidies that have changed the balance between state and private ownership of reindeer. both these factors have greatly contributed to the herders’ dependence on visiting towns, where they now own flats, and on selling reindeer products, upon which they are increasingly reliant for financial security. keywords komi; post-socialism; reindeer herding; russia; social change; socialism. correspondence k. v. istomin, max planck institute for social anthropology, advokatenweg 36, de-06114 halle/saale, germany. e-mail: istomin@eth.mpg.de doi:10.1111/j.1751-8369.2009.00108.x the effect of state policy upon the life, social organization and culture of aboriginal peoples has been one of the most important topics of research in siberian anthropology (fondahl 1989; slezkine 1994), particularly since the break-up of the soviet union (ventsel 2005: 24–25). indeed, a vast body of literature exists describing how the socialist and post-socialist policies of the soviet union/ russian federation have influenced the aboriginal peoples of the russian north (for a review see ventsel 2005). it has often been observed that at the state level both soviet and, to a lesser degree, post-socialist russian policies towards these peoples were highly centralized, uniform and inflexible, and paid little attention to the local circumstances and particularities of individual communities (e.g., fondahl 1989; shindler 1991; slezkine 1994). for example, there were attempts to organize a post-soviet clan-based administration for peoples without clans (pavlov 2003). however, a number of studies undertaken during the last decade have demonstrated that the interpretation of these state policies varied significantly in different parts of the soviet/ russian north, and sometimes led to markedly different effects, even among different groups of the same people in the same region (e.g., gray & stammler 2002; stammler & ventsel 2003; klokov 2004). one example, which has received relatively little detailed attention, is the impact that soviet/russian state policy has had on the land use strategies and migration patterns of northern nomadic reindeer herding peoples. it has been documented that the central soviet administration generally regarded nomadism as a backward way of life, which, although tolerated for economic reasons, was generally viewed as being inconsistent with modernity and destined to disappear (fondahl 1989; slezkine 1994; vakhtin 1994; golovnev & oshirenko 1999; konstantinov 2002). therefore, up until the beginning of the 1980s, local authorities throughout the russian north were urged to apply policies that would foster sedentary living. they achieved this by providing reindeer herders with free flats in villages, forcing the transition from polar research 28 2009 282–297 © 2009 the authors282 mailto:istomin@eth.mpg.de “family nomadism” to “productive nomadism” (i.e., the system in which male and some female members of reindeer herding families move, while the majority of female members and children pursue a settled way of life in a town or village), as well as introducing “shifting pasturing” (fondahl 1989; krupnik 2000; jernsletten & klokov 2002). “shifting pasturing” refers to the system in which several different groups of reindeer herders (mostly male) alternate between undertaking pasturing shifts in the tundra (lasting from one to three months), and periods of rest with their settled families in a village. furthermore, the direct intervention of the state specialists in determining migration routes and schedules, which happened in many places, more often than not decreased the length of migrations, and bound them to a region around the sedentary bases of the enterprises (syrovatskij 1975; anderson 2000; gray 2005; ventsel 2005). it was only towards the middle of the 1980s that the transition from family to productive nomadism was officially recognized to be neither economically viable nor socially helpful in all regions (zabrodin 1980). the degree and consistency with which these policies were carried out varied substantially from one region to another, and therefore affected reindeer herding groups in very different ways. for example, the soviet policy implementation for the european and yamal groups of nenets reindeer herders resulted in a decrease in the length of their annual nomadic migrations, and an increase in the time spent in proximity to the “sedentary bases” (golovnev & oshirenko 1999; tuisku 2002; but see stammler 2005 for an opposing view), whereas the migration patterns of the yenisey group of nenets apparently remained unchanged (klokov & šustrov 1999). interestingly, post-socialist transformations—which included the lifting of the state “sedentarization” policy and the endorsement of nomadism in official discourses—also affected the yamal and european nenets in different ways. whereas the yamal nenets’ migration routes remained similar to those of the late soviet period (golovnev & oshirenko 1999) and, according to stammler (2005), the pre-soviet period, the migration routes of the european nenets have significantly changed (tuisku 2002). this shows that detailed regional studies are needed in order to understand better the effects that state policy may have on mobility and land use. this paper focuses on documenting and explaining changes in the migration pattern of a community of komi reindeer herders, who inhabit the eastern part of the bol’šezemel’skaja tundra and the northern part of the komi republic (formerly known as the komi autonomous soviet socialist republic [assr]), in the north-east of the european part of the russian federation (fig. 1). the primary aims of this paper are threefold: (1) to document the changes in the migration pattern of a group of komi reindeer herders during the soviet and postsoviet periods (i.e., mainly from the 1960s period of amalgamation policy to the post-socialist present day); (2) to discuss these changes in relation to state policy fig. 1 map showing the location of the study area in northern russia. komi reindeer herders’ mobility and land usem.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors 283 vis-à-vis northern reindeer herders; and (3) to propose hypotheses for the causal relations between state policy and the changes in the herders’ migration patterns. background the komi began herding reindeer around three centuries ago, which, interestingly, corresponds with the age of “large-scale” reindeer herding per se (krupnik 1976, 1989). as often stated in russian literature, historically, the komi adopted reindeer herding from the nenets (krupnik 1989, 2000; žerebcov 1982; konakov & kotov 1991). however, this adoption most probably concerned transport reindeer herding, whereas the “large-scale” reindeer herding system was developed by the komi independently from the nenets, although not in isolation from them (istomin 2004; see also habeck 2005 for a discussion). commencing in the ižma region of the bol’šezemel’skaja tundra, in the area that is now the komi republic and the nenets autonomous okrug, the komi increased the numbers and sizes of their herds over a short period of time (islavin 1847; kercelli 1911; babuškin 1930), expanded into the khanty-mansi areas in the east, and even emigrated to the kola peninsula in the west (konakov & kotov 1991; took 2003). the communist revolution in russia and the subsequent civil war caused economic stagnation, which paralysed russia, including komi reindeer herding (istomin 2004). the history of komi reindeer herding during the communist era can be divided into the following seven periods, which were essentially similar all over the russian north (fondahl 1989; sergeev 1955; muhačev 1990; slezkine 1994; vakhtin 1994): (1) the period of the civil war, from 1918 to the beginning of the 1920s; (2) the period of restoration, in the 1920s; (3) the collectivization epoch (from the russian, kollektivizacija), in the first half of the 1930s; (4) the first period of stagnation, from the end of the 1930s to the middle of the 1950s; (5) the amalgamation epoch (from the russian, ukrupnenije), from end of the 1950s to the middle of the 1970s; (6) the second period of stagnation, from the second half of the 1970s to end of the 1980s; and (7) the period of re-privatization and crisis, from the 1990s to the beginning of the 2000s. the first and second periods relate to the establishment of political control by the communist government over reindeer herders, and the building of official institutions for their administration. the period of collectivization was marked by strong intervention by the state into the life of reindeer herders. this intervention was directed mainly towards the system of property relations, whereby independent reindeer herding entities became local collective state farms (in russian: kolhoz; plural kolhozy). after the period of stagnation, when the issues of aboriginal peoples were mainly neglected by the state, the second reconstruction era (which coincided in time, but was not limited to the amalgamation policy) emerged. during this period a strong attempt was made to reform both the technology of reindeer herding and the herders’ way of life: by creating new state farms (in russian: sovhoz; plural sovhozy) in place of semi-independent kolhozy, closing/merging villages and encouraging sedentary life, etc. this period is the focus of this paper. study site and methodology this paper focuses on the reindeer herding state farm (sovhoz) bol’šaja inta, which is one of three reindeer herding enterprises of the komi republic’s reindeer herding region of inta (in russian: intinskij rajon). the other two enterprises of this region are petrun’sky (petrun’ village) and fion-a (abez village). the bol’šaja inta sovhoz, which used to be the supply enterprise of the intaugol coal-mining company during the soviet period, emerged as a reindeer herding enterprise during the 1960s, by acquiring (during the period of amalgamation) seven smaller collective farms (kolhozy), which had been established during the 1930s (smetanin & savel’eva 2004: 336; tables 1, 2). to differentiate between the sovhoz from the socialist era and the post-socialist sovhoz, the latter are hereafter referred to as “modern sovhoz”. during the period of this research, bol’šaja inta consisted of five brigades (in russian: brigada; plural brigady), each of which was historically linked to a particular village and kolhoz: the first and fourth brigades were those from the village of adzvavom, the fifth brigade was from its neighbouring village adzva (formerly known as lar-van’-ig), whereas the second and third brigades originated from the villages of kočmes and larko, and nidz’el’, respectively. the brigades from the three remaining kolhozy, which were also acquired by bol’šaja inta (i.e., those from the villages of jag-el’, dresjanka and kosjuvom) were most probably integrated with those of their closest neighbours, i.e., with the first, fourth and fifth brigades, and the second and third brigades, respectively. the second brigade ceased to exist towards the end of 2005, and although there has been talk of its re-establishment, this prospect remains unclear. anthropological fieldwork for this paper consisted of three expeditions with brigades of the bol’šaja inta sovhoz. the first expedition took place in 2001 (september–november), the second took place in 2002 (june–december) and the third took place in 2003 (january–february). during these expeditions, nine months were spent with the second and third brigade, one month was spent with the first and fourth brigade, komi reindeer herders’ mobility and land use m.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors284 and one month was spent with the fifth brigade. during various intervals—from august 2001 to february 2003—a period of over a month was spent interviewing retired reindeer herders in small remote villages: adzvavom (two weeks), kosjuvom (one week), petrun’ (three weeks) and rogovaja (three days). a number of days were also spent with state farm officials, collecting relevant maps and asking general herding questions. the research included participant observation and interviews that were conducted in both the komi and russian languages. the interviews were informal, and no specifically designed questionnaires were used. the interviewing process was repeated several times, with different individuals and groups of herders, in order to crossreference the data. participant–observation, used to study the technology of reindeer pasturing, essentially involved practical work among reindeer herders. december 2001 was spent perusing russian state archives in both inta and syktyvkar. the majority of information was obtained from the komi national archive (kna), as this is where most information is held, and obtaining access to the inta files proved difficult. the reliability of soviet reindeer herding statistics is often questioned. this especially concerns those relating to private reindeer (tuisku 2002; stammler & ventsel 2003), collectivized reindeer of the 1930s–40s (slezkine 1994; habeck 2005) and the structure of reindeer losses (konstantinov 2002; konstantinov & vladimirova 2006). however, in the context of this research, little else could be done other than to accept the statistics at face value. the figures representing the winter pastures and migration routes of the bol’šaja inta sovhoz brigades are based both on maps obtained from the sovhoz administration and the herders’ knowledge. the sovhoz maps had neither coordinates nor scaling. however, the historical aspects of the migration routes and winter pastures (i.e., where the herders used to travel and pasture their reindeer prior to the relatively recent changes) were drawn by veteran herders, using accurate topographical maps. although much care has been taken to reproduce, as accurately as possible, the sovhoz maps and combine them with the herders’ knowledge of pastures and migration routes, they should be treated as approximate representations. table 1 kolhozy (local collective state farms) in the inta region prior to amalgamation. the names of the kolhozy were taken from archival data in the year 1945 (kna 2576). the names of the villages, to which the kolhozy correspond, were provided by veteran reindeer herders. name of kolhoz corresponding village budenogo adzvavom kirova it is likely that the kirova kolhoz belonged to the nenets autonomous okrug (nao), as it was only after merging with budenogo in 1958 that the new enlarged kirova became registered and known as a komi kolhoz (kna 4859). adzva was formerly known as lar-van’-ig, although it is not clear when the village was renamed (roščevskij et al. 1999: 219). adzva (formerly known as lar-van’-ig) timošenko in 1958 the timošenko kolhoz was renamed frunze (kna 4859). jag-el’ vinogradova nidz’el’ čapajeva kosjuvom kosju dresjanka sotsolenevod in 1945, sotsolenevod was not registered as a kolhoz belonging to the inta region (kna 2576), as it belonged to the nao (kna 3794). it was not until 1953, when sotsolenevod merged with čapajeva to form the molotova kolhoz, that it became registered as a komi kolhoz (kna 3794). kočmes & larko table 2 amalgamation of the kolhozy (local collective state farms) in the inta region. 1960 molotova kolhoz (kosjuvom + kočmes + larko) frunze kolhoz (jag-el’) kosju kolhoz (dresjanka) stage 1 sovhozb amalgamation of bol’šaja inta 1961 kirova kolhoz (adzva + adzvavom) vinogradova kolhoz (nidz’el’) kirova kolhoz acquired the vinogradova kolhoz 1963 kirova kolhoz (adzva + adzvavom) leninaa (petrun’) kolhoz abolished in the inta region. both kolhozy were subordinated to the pechora region. 1967 kirova kolhoz (adzva + adzvavom) stage 2 sovhoz bol’šaja inta acquired the kirova kolhoz alenina kolhoz (now the sovhoz of petrun’) was based in the village of petrun’ which is to the east of inta. bsovhozy, new state farms. komi reindeer herders’ mobility and land usem.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors 285 changes in mobility and land use the most notable changes in the reindeer herders’ pattern of migration in bol’šaja inta occurred progressively, as a result of their abandonment of winter pastures. the reduced length of the herders’ migrations means that they no longer travel as far as they did several decades ago, to pastures located in the southern range of their migration route. in the following sections these changes in mobility and land use will be outlined chronologically, ranging from the sovhoz period (early 1960s) to that of the present day. it was not possible to map individual migration routes before the 1960s because of the lack of archival and detailed anthropological data. however, veteran reindeer herders said that the migration routes used prior to the 1960s were essentially the same as those used in the early sovhoz period (early 1960s). migration routes and winter pastures during the early 1960s figure 2 shows the migration routes and arrangement of winter pastures during the early 1960s, following the first stage of the kolhoz amalgamation (in russian: ukrupnenije), and the establishment of the bol’šaja inta sovhoz. the migration routes a and b are those of the brigades belonging to the kirova kolhoz that did not merge with the sovhoz during the first stage of bol’šaja inta’s fig. 2 the migration routes and arrangement of winter pastures in the early 1960s. komi reindeer herders’ mobility and land use m.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors286 amalgamation process. these brigades included the two from the village of adzvavom (currently known as the first and fourth brigades) and that of the village of adzva (currently known as the fifth brigade). all three brigades shared the same migration route, except the fifth brigade, which had its own section of migration route that branched off along the way. these three brigades, unlike the others of bol’šaja inta, had winter pastures that were located near the pechora river, rather than in western siberia. according to the veteran herder aleksej (first brigade), the first and fourth brigades had their winter pastures near the village of ust’-usa (close to the new “petroleum” town of usinsk), whereas those of the fifth brigade were east of the town of pechora. aleksej explained that the migration routes followed the usa river, which intersects with the pechora river, and leads to the winter pastures. similarly, the veteran herders mihail and aleksej (second brigade), and ivan (third brigade), recalled their transural migrations with nostalgia, and drew the routes on the map with great precision. the information provided by the herders with regard to the location of their migration routes and winter pastures is supported both by published maps (ige 1964: 98) and by maps held by the sovhoz (ma 1982). migration routes and winter pastures during the late 1960s figure 3 shows a change in the migration routes and winter pastures of the first, fourth and fifth brigades, which occurred during the late 1960s. according to aleksej (first brigade), the three brigades were no longer permitted to travel to the pechora region, which they had always done in the past, once they merged with the bol’šaja inta sovkhoz. instead, they were given new winter pastures behind the ural mountains, near saranpaul’ (further south from those of the second and third brigades), and had to create a new section of migration route (g) that joined up with that of the second and third brigades. this meant that the brigades from adzvavom and adzva were forced to abandon not only their pechora winter pastures but also the sections of their migration routes that led to them. aleksej reported that no reindeer herding brigade (from bol’šaja inta) ever travelled to the pechora region after this period. the reasons for relocating the winter pastures of the first, fourth and fifth brigades become clear if one takes into account the development of the oil and gas industries, which was initiated in the region during this period. in 1964, the decision was taken to establish a permanent settlement in proximity to the usinskaja oil well in the middle of the first and fourth brigades’ winter territory; in 1971, this new settlement was officially named usinsk, and acquired city status in 1984. in 1964, a gas deposit was discovered in pechora, near the mouth of the vuktyl river (the upper part of pechora), and by 1967 a major industrial plan to extract the gas had been developed (smetanin & savel’eva 2004). around the same time, the bol’šaja inta sovhoz acquired the kirova kolhoz, which included the brigades from the villages of adzvavom and adzva, as part of the second stage of the amalgamation process (described earlier), and changes were made to the location of winter pastures. it is highly likely, therefore, that these changes correspond with the plans of industrial development. no further mergers or acquisitions occurred from this point onwards, and the brigade structure remains the same today as it was in 1967. migration routes and winter pastures during the mid-1970s figure 4 shows the abandonment of the trans-ural winter pastures (e) and the section of migration route that led to them. according to aleksej (first brigade), the brigades from adzvavom and adzva were the first to cease pasturing their herds behind the ural mountains, in 1974 (some 31 years ago), which signifies that they travelled there for a period of only seven years (1967–1974). similarly, serafim, aleksej and mihail (second brigade) reported that the two remaining brigades (the second and third) continued pasturing their herds in western siberia for a further two years, before abandoning the practice themselves in 1976. instead, the herders reported that all of the brigades started to use winter pastures that were situated close to the ural mountains (i.e., not on the other side of them), near the village of kožim and a place called tundra pjaseda (d); however, to a certain extent, they probably used some of the pastures located around the town of inta in a similar way as they do today. interestingly, according to the map of 1964, the pastures located near kožim, and tundra pjaseda, were marked as being “reindeer passages” rather than winter pastures (ige 1964: 98). this meant that these pastures were not intended to be the final destination of the migration route, where reindeer would be pastured for about 4–6 weeks before starting the migration back towards the north. however, it is not exactly clear which winter pastures each brigade was meant to use during the mid-1970s, as no maps from this period could be found. nevertheless, it is evident that the winter pastures located in western siberia would almost certainly have been available, given that, to this day, they remain part of the official winter pastures of bol’šaja inta. komi reindeer herders’ mobility and land usem.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors 287 migration routes and winter pastures from 1982 to the present day figure 5 shows the official arrangement of pastures from 1982 onwards, which correspond with those presented in the sovhoz map (ma 1982). although the map was printed in 1982, there is no indication that any further official land use changes have since occurred, as the sovhoz has had no amendments made with regard to pastures, and continues to instruct the reindeer herders to make movements that correspond to these maps. it was pointed out earlier that the pastures located near the ural mountains, currently marked as being winter pastures, were, in the past (i.e., during the early 1960s) considered to be “reindeer passages”. similarly, the sovhoz map of 1982 shows that the winter pastures of all brigades are now located much further north than previously. in fact, the 1964 map shows the current winter pastures as being located in areas that were previously marked as either spring/autumn pastures or “reindeer passages” (ige 1964: 98). the only exceptions are the winter pastures located behind the ural mountains (now kept as reserve pastures), which have not been exploited by a bol’šaja inta brigade since 1976. according to aleksej, ivan and petr (first brigade), the brigades from adzvavom and adzva (first, fourth and fifth brigades) stopped pasturing their herds near the ural mountains in 1982. this coincides with the date that the sovhoz map was issued (ma 1982), showing the winter pastures of these brigades to be located elsewhere (fig. 2). fig. 3 the migration routes and arrangement of winter pastures in the late 1960s. komi reindeer herders’ mobility and land use m.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors288 however, according to vasilij and aleksej (second brigade), and ivan and prokopij (third brigade), in 1990 the second and third brigades also stopped winter pasturing near the ural mountains. consequently, between 1982 and 1990, a further abandonment of winter pastures took place (of those near the ural mountains). some abandonments resulted from a possible reorganization of pastures, whereas others resulted from the general trend of not travelling so far south. it should be noted that more recently (from 2001 to the present day) the first and fourth brigades have been observed to use pastures belonging to the neighbouring haruta reindeer herding enterprise: this resulted from the lack of prosperity of a number of the haruta enterprise brigades, who no longer used their winter pastures. these pastures are located to the north and north-west of adzvavom. summary of change in migration routes and winter pastures figure 6 shows the general “retreat” from the migration routes and trans-ural winter pastures in the bol’šaja inta region from the early 1960s to the present day. although some of the winter pastures are no longer available (i.e., those to the west), those near the ural mountains and in western siberia remain accessible, despite having been abandoned. it is apparent that all of the brigades no longer fig. 4 the migration routes and arrangement of winter pastures in the mid-1970s. komi reindeer herders’ mobility and land usem.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors 289 travel as far south as they once did, and the modifications to the official “pasture maps” over the years appear to reflect the reindeer herders’ changing pattern of land use, rather than change having been dictated by the state. the migration routes a (first and fourth brigades), b (fifth brigade) and c (second and third brigades) are approximately 29, 31 and 42% shorter, respectively: i.e., 34% shorter on average. for example, the length of the transural migration route (of the second and third brigades) has decreased from 720 km (one way) to 410 km. for the sake of simplicity, the migration routes were measured in a straight line: the actual lengths are considerably longer. there were two separate reasons for the abandonment of some winter pastures, and the sections of migration routes that led to them. the winter pastures located near pechora were essentially abandoned following a reorganization of reindeer herding territories during the sovhoz amalgamation period, by a direct order of the state, whereas those located south of inta (near the village of kožim and on tundra pjaseda) and in western siberia were abandoned because of a range of complicated social, cultural and political factors, but not by direct state order. these factors are analysed in a later section. changes to state policy the situation after the 1960s amalgamation (ukrupnenije) according to archival data, the bol’šaja inta herd comprised between 10 000 and 12 400 reindeer (excluding transport reindeer), before calving, from 1970 to 1983. consequently, there should have been a minimum of 2000 and a maximum of 2480 reindeer (before calving) in each brigade, assuming that all five brigades had comparable herd sizes. fig. 5 the migration routes and arrangement of winter pastures from 1982 to the present day. komi reindeer herders’ mobility and land use m.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors290 following amalgamation, the status of reindeer ownership changed. during the kolhoz period, the majority of reindeer were owned by the kolhoz, and were supposedly collective property, whereas during the sovhoz period they became state property. apart from this, a limited number of private reindeer (officially named personal reindeer) were officially tolerated. the number of private reindeer authorized in the komi assr and the nenets autonomous okrug was 30 animals per herder (smetanin & savel’eva 2004: 504). (tuisku [2002] analytically differentiates between private and personal property of reindeer: she prefers to use the term “personal property” to designate the right of kolhoz/sovhoz workers to a certain number of reindeer pastured in a brigade’s herd, whereas “private reindeer” can be owned only by independent herders who do not work for collective/state enterprises. although the authors agree with tuisku and others [fondahl 1989; anderson 2000; konstantinov 2002; ventsel 2005; konstantinov & vladimirova 2006] that affiliation with a [post-]socialist enterprise brought about a number of important constraints on, and possibilities for, managing private property, we believe that this affiliation influenced the strategy of exercising property rights, rather than the rights themselves. we see no heuristic value in differentiating between “private” and “personal” property, and believe that such a differentiation in official soviet-era documents has ideological rather than empirical relevance.) despite the strict limits on numbers, the percentage of privately owned reindeer throughout the komi republic, and the soviet union in general, slowly grew during the entire sovhoz period. this tendency became apparent fig. 6 the overall change in migration routes and winter pastures from the early 1960s to the present day. komi reindeer herders’ mobility and land usem.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors 291 during the 1950s, and especially during the 1960s, when the punishment for exceeding the permissible limit of “personal property” became less severe, whereby a guilty party was generally fined rather than given a prison sentence (smetanin & savel’eva 2004: 604). the growth of private herds was most significant in the yamal, where, by the end of socialist period, more than 40% of the total herd was privately owned (stammler & ventsel 2003: 331; klokov 2004: 60). the figure for the komi assr— 13% in 1987—is more modest, and closely resembles that of yakutia, of about 10% (stammler & ventsel 2003). it should be noted, however, that the statistics on private herds may not be entirely correct, because of the attempts of the herders to hide the exact number of their private animals, and thus avoid fines. we believe, however, that the statistics still reflect general practices, and are useful when comparing different regions throughout russia. the size of the brigades increased after the transition from kolhoz to sovhoz. according to the herders, during the kolhoz period the brigades of bol’šaja inta generally had five or six herders each, as opposed to between eight and 10 during the sovhoz period. this change could be attributed to the increased number of reindeer managed by each brigade. indeed, the herders recall that during the kolhoz period there were many more brigades than at present, and the size of their productive herds—at around 1000 reindeer per brigade (before calving and excluding draft transport reindeer)—was much smaller. the herders’ general statement that herd sizes in the inta region were smaller during the kolhoz period, compared with those of the present day, is supported by archival material. for example, there were 1408–3331 productive reindeer (after calving) at the budenogo kolhoz (adzvavom) between 1945 (kna 2576) and 1959 (kna 4895). considering that there were (and still are) two adzvavom brigades, it is perfectly plausible that two productive herds of 1000 animals each (before calving) could have accounted for up to 3300 head of reindeer (after calving), given the productive capacity of 65% for a typical komi herd (dwyer 2006). according to herding veterans, the number of herders living in a tent (in komi, čom; in russian, čum) was around five or six during the kolhoz period (as opposed to between eight and 10 during the sovhoz period), and generally consisted of two families, each of which occupied a separate side of the čom. in addition to the duty herders, there would have been at least two female tent workers and several children. this closely resembles the descriptions from the beginning of 20th century that among komi a čom usually accommodated two families (kercelli 1911), consisting of husbands, wives and their unmarried children. this pattern changed considerably after the amalgamation, mainly as a result of the gender drift (see vitebsky & wolfe 2001). the decline in the number of female tent workers apparently accelerated during the sovhoz period (see dwyer 2006). furthermore, probably for the first time in komi history, the herders living in the tent often belonged to more than two families. although the implications of these social changes have not yet been researched, they would most likely have influenced the work organization of female tent workers, considering that the tent has only one stove, one set of common equipment and a finite amount of space (e.g., for making clothes). the reasons for the gender drift are considered to be complex, and their detailed discussion lies outside the scope of this paper (see vitebsky & wolfe 2001). it is, however, worth mentioning that the outflow of women was strongly supported by the state as an important step in the transition from “family” to “productive” nomadism. in the komi republic, girls were encouraged to become sedentary by both the system of school education and public media, which represented the tundra as a male space, generally unsuitable for women. komi reindeer herding, unlike many other reindeer herding communities, did not develop on the basis of an “extractive economy” (e.g., hunting, fishing and gathering), but rather on that of a “productive economy”, which included cattle breeding and agriculture (istomin 2000). as a result, present-day komi reindeer herders have strong connections with family members who live a sedentary village way of life, and the herders return to these settlements during the winter—as their winter pastures are located close to the villages—to trade and exchange goods, as well as to visit family members. reindeer herders, despite being nomadic during their working lives, usually retire to villages with their family, and sometimes build their own wooden houses. since the development of towns such as inta and vorkuta, a komi family may now consist of reindeer herders, coal miners, shop assistants, cattle breeders and agriculturalists. household diversification is not unique to the komi (see, e.g., king 2003). the process of amalgamation meant that all villages saw their populations decline quite radically, and it is probable that some villages remain totally uninhabited. for example, the village of adzva had a population of 242 in 1939, which decreased to 63 during the sovhoz period (in 1970), and to only 16 in 1995 (roščevskij et al. 1999: 219). this depopulation was related to the state policy of closing down small villages, and centralizing the population in small towns and large villages, in order to facilitate logistics, improve the supply of goods and services, and decrease the population outflow from villages to cities (the so-called policy of unviable villages; kovalev & šapošnikov 1977: 36; apsh 1980: 44–53). the inhabitkomi reindeer herders’ mobility and land use m.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors292 ants of the villages declared unviable were offered free flats in towns and larger villages, where the headquarters of their sovhoz were usually located (kovalev & šapošnikov 1977: 33). at the same time, the supply/support to these unviable villages was cut back, essentially forcing the local population to relocate. the major effect that these policies had on reindeer herding families was that of segregation. prior to the establishment of the sovhoz, the typical family type of the northern komi, especially the reindeer herders, was the so-called large “undivided family” (konakov & žerebcov 1994; solovyev, pers. comm. 2002). these comprised several related nuclear families, typically two or three, joined together to form one household. for example, such a unit could be made up of the families of two brothers and the family of one of their married sons. the unit held private property in common, for example, a house in a village (konakov & žerebcov 1994). usually, an undivided family included nomadic reindeer herders as well as settled non-nomadic agriculturalists or farmers, and, whilst one of the related nuclear families travelled in the tundra, the remaining sedentary nuclear families stayed in the village, and worked both within the kolhoz system and independently (each kolhoz member had a right to a small plot of land and several animals). all the products derived from reindeer herding, agriculture and farming were considered to be the property of the undivided family, and were shared accordingly. furthermore, when it was time for the herders to return to the village to either visit (during the winter) or permanently retire, they lived in the house of their undivided family, which they considered to be partly their own (solovyev, pers. comm. 2002). the state policy to provide accommodation meant that each nuclear family received its own flat, which, subsequently, changed the distinctive komi family structure. although today there is still a large degree of exchange of goods and services that takes place between nomadic reindeer herding nuclear families and other related families who remain sedentary in villages and towns, property is no longer considered to be a common commodity. therefore, dealings between related nuclear families are now based on the principle of more or less balanced reciprocity, whereby the help provided by one family is paid back in a similar manner. consequently, whereas during the kolhoz period, and even prior to it, reindeer herders generally either retired to villages with family members or died whilst living and working in the tundra, during the sovhoz period they either applied for state flats (if they were entitled to them) or purchased real estate. this resulted in herders spending less time in the tundra, and more time visiting towns and villages, and occupying their newly acquired accommodation during the winter months, once they had reached their winter pastures. the present situation (post-socialism) following the break-up of the soviet union in 1991, the former communist sovhoz of bol’šaja inta, like many others throughout the komi republic and russia, became a quasi-independent enterprise, as a result of the privatization process. as bol’šaja inta was a “supply enterprise” to the intaugol’ state coal company, as noted earlier, both companies were privatized simultaneously in 1992 (kolegov 2004: 14). the komi style of reindeer herding in the inta area, and probably throughout the komi republic, was relatively unaffected by the sovhoz administrative period, at least in the sense that reindeer populations and control remained quite stable. however, following the privatization of bol’šaja inta, the ownership structure of the reindeer herds changed. whereas formerly the herds were predominantly owned by the sovhoz (during socialism), reindeer herders steadily increased their ownership of reindeer (from 1991 to the present day), once the previous private reindeer ownership restrictions were lifted. this is corroborated by state statistics, which show that although the modern sovhoz continues to own the majority of the herds (close to 2000 reindeer per brigade), there has been an increase in the numbers of private reindeer owned by the herders (table 3; also see habeck 2005: 104). this recent trend is partly in response to the fall in state subsidies, and the resultant decline in both herders’ salaries and the general availability of goods and services that are important to them, for example, helicopters bringing in a regular food supply and the materials table 3 changes in reindeer ownership in the komi republic. 1990 1998 1999 2000 2001 2002 number of reindeer owned by enterprises and former sovhozya 102.3 83.9 76.5 76.0 76.1 75.0 number of reindeer owned by herders in thousands 21.3 26.8 23.8 29.0 24.7 25.8 number of reindeer owned by herders unmanaged by the stateb n/a 2.2 2.0 5.1 5.1 5.1 total in thousands 123.3 112.9 102.3 110.1 105.9 105.9 asovhozy, new state farms. bthis category consists mainly of reindeer owned by households of free nenets reindeer herders (jamb-to), who operate in the komi republic. source of data: kssc (2005). komi reindeer herders’ mobility and land usem.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors 293 necessary for herding practices. consequently, the ownership of private reindeer is of paramount importance to herders, given that the sale of reindeer products derived from their private herds generally account for over half of their annual income. access to the village or town (especially inta) in winter has also become increasingly important, as the reindeer herders spend more of their time trading to generate sufficient income to purchase food and materials for the following year in the tundra, as well as to supply their family with meat and furs. they also take the opportunity when in a village or town to try to find wives, or to spend time with their partners who either do not work in the tundra or have taken time out, for example, for child-bearing or health reasons. discussion although some of the changes detected in the pattern of bol’šaja inta’s land use—namely, the abandonment of winter pastures near usinsk and pechora in the middle of the 1960s—can be attributed purely and simply to industrial development, this explanation does not apply to the abandonment of pastures near the ural mountains. we argue that it was predominantly the closure of small villages, and the resettlement of their inhabitants to larger villages and towns, as well as the gender drift and recent redistribution of reindeer from state to private property, that spurred the reindeer herders to abandon these pastures. indeed, the beginning of this abandonment corresponds quite remarkably with the period during which most reindeer herders received their state flats. it appears to us that the resettlement campaign and the issuing of flats triggered the break-up of the typical komi undivided family structure into european nuclear families, with the result that the ties, which included common ownership of property, that linked nuclear families into the larger grouping were no longer as strong as they had once been. this resulted in nomadic families desiring or needing to visit the village or town (where their flats were located) more regularly, and for longer periods of time. these visits could only be made during the winter months, when the herders reached the southern range of their pastures. this meant that if they wanted to stay in their flats, they were no longer able to travel hundreds of kilometres further south (beyond the village or town) to their distant winter pastures. as a result, the herders’ migration routes receded, and the pastures they began to use during the winter months were those previously regarded as either spring/autumn pastures, or “reindeer passages” (ige 1964: 98). it is probably for this reason that when the new sovhoz maps were produced in 1982 (ma 1982), following the murmansk prospecting expedition, the winter pastures were drawn up, to some extent, on the basis of where the brigades were actually pasturing their herds, rather than where they were meant to have been pasturing them. there is, of course, a whole host of other reasons why reindeer herders spent increasing periods of time in the village or town. firstly, the difficulty the herders experienced in finding partners (caused by the gender drift) was a major concern, and more frequent visits to town increased their chances of meeting a potential partner. secondly, as the town and villages developed, so did living standards, and there is no doubt that these became increasingly attractive to the herders who spent most of their time travelling in the tundra under quite difficult conditions, and with only the bare essentials for living. thirdly, during the sovhoz period, a reindeer herding family was permitted 30 private reindeer (smetanin & savel’eva 2004: 504); however, since the lifting of ownership quotas (following the end of socialism), there has been a steady trend towards the increase of private ownership, and the decrease of state/enterprise ownership (i.e., the modern post-socialist sovhoz). this trend is predominantly the herders’ response to the low wages and decreasing supplies they receive from the modern sovhoz, and there is every indication that this situation is likely to continue. in fact, reindeer herders have already become more reliant upon private income that is derived from their private herds than on the payments made by the modern sovhoz. this means that during the winter months much time and effort has to be spent in the town preparing and selling reindeer products. to broaden this discussion, it is interesting to note that habeck, who studied reindeer herding in the komi republic, is also of the opinion that the reasons for the abandonment of winter pastures are mostly of a social and economic nature, notably the herders’ preference for pasturing their animals close to villages (habeck 2003: 83–84). nevertheless, although the abandonment of winter pastures has taken place throughout the komi republic, there is one exception to this generalization. of the four eastern komi enterprises (bol’šaja inta, petrun’, abez’ and vorkuta) that officially have winter pastures in western siberia, only the herders from vorkuta still use them. vorkuta is situated more than two and a half times closer to the kara sea compared with inta (fig. 2), and has fewer pastures between the town and the coast, and hence the herders probably have little choice other than to continue using their trans-ural pastures. this is supported by the director of the vorkuta “olenevod” sovhoz, who stated that “his brigades must continue (or resume) their migrations to the remote winter pastures [otherwise] he anticipates largescale pasture degradation in the whole region around vorkuta” (habeck 2003: 84). komi reindeer herders’ mobility and land use m.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors294 another reason for the vorkuta herders not abandoning their trans-ural pastures could be that the town of salehard (salekhard), situated along this route, has an important marketplace, where they can trade the products of their private reindeer. it should be noted, however, that this is hardly the main reason, as the demand for reindeer products is significantly higher in vorkuta compared with salehard (salekhard). hence, purely from an economic point of view, trading in vorkuta would be more profitable for the herders. consequently, the abandonment of winter pastures, despite being linked to the herders’ need/desire to visit the village or town, is seemingly also dependent upon their location. for example, if inta were to have been built 100 km further south, then perhaps the bol’šaja inta’s trans-ural winter pastures would not have been abandoned, as their location would have been much closer to the town. conclusion the evidence presented in this paper shows that in the bol’šaja inta region the reindeer herders’ migration routes became shortened by an average of 34% from the early 1960s to the present day. this was a consequence of the gradual abandonment of winter pastures, notably those situated near pechora and the ural mountains, as well as those located behind the ural mountains in western siberia. the decrease in nomadic mobility during the socialist period was described in a number of regions of the russian north (e.g., anderson [2000] for taimyr, stammler & ventsel [2003] and ventsel [2005] for yakutia, gray [2005] and nuvano [2006] for chukotka). however, this decrease usually resulted from the direct influence of the state, which allocated specific pastures and migration routes for collectivized reindeer herders, and considered the long migrations, in which these people were traditionally engaged, economically unviable. what makes the case of komi reindeer herding interesting, however, is that quite a significant part of the grazing territory has been abandoned by the herders, against (rather than following) the will of the state. on the other hand, as clearly indicated in this paper, this abandonment was still a result, albeit a rather unexpected one, of state policy. it was found that changes to the herders’ movements and of land use, which occurred over a period of several decades, probably arose as a result of the closure of small “unviable” villages, and the subsequent relocation and centralization of the local population and administration to larger villages and towns. during this process, most families received new state-financed flats, and the numerous individual village kolhozy were amalgamated to form a single state enterprise (sovhoz), located in the town of inta. these events led to a myriad of social, economic and political changes that, as time progressed, increased the herders’ need and desire to visit the town during the winter months, which was achieved by gradually reducing the length of their migration route, and hence the range of their winter pastures. it would appear that the location of the town or village is an important factor determining whether or not reindeer herders abandon trans-ural winter pastures. in the case of vorkuta, the fact that the town is located so far north, and that there are few pastures located between the town and the coast, means that the herders have little choice other than to travel further south, beyond the town, to their more distant winter pastures. finally, the other major reason for the abandonment of pastures was plainly and simply a result of land encroachment by the oil and gas industry. winter pastures situated near pechora (formerly used by ust’-usinskiy and kirova) are now home to the oil town of usinsk. acknowledgements the fieldwork undertaken amongst komi herders in the bol’šezemel’skaja tundra was financed by a joint interdisciplinary research scholarship from the british natural environment research council and the british economic and social research council (esrc). the writing of this paper was also made possible thanks to a post-doctoral research fellowship funded by the esrc, and another funded by the max-planck institute for social anthropology and the martin-luther university halle-wittenberg. the authors wish to thank their numerous komi and russian collaborators, in particular, the jangasov, šurakov, alekseevič, larionov, filippov, kanev and semjaškin extended families for their assistance, patience and extraordinary generosity. we should also acknowledge mr a. makarčuk from the bol’šaja inta sovhoz administration for his assistance and cooperation. finally, we wish to thank our colleagues, particularly tim bayliss-smith (department of geography, cambridge university) and joachim otto habeck (max planck institute for social anthropology) for their suggestions and criticisms, ian agnew (cartographer at the department of geography, cambridge university) for having skilfully reproduced and improved the diagrams and maps in this paper, and, last but not least, mrs eileen j. dwyer for her editing contribution. we also thank dr vladimir v. solovyev, department of ethnography/cultural anthropology, institute of language, literature and history, komi scientific centre, ural division of the russian academy of sciences. the komi reindeer herders’ mobility and land usem.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors 295 komi national archive is located at sovetskaya ulitsa 26, syktyvkar, komi republic, russia. references anderson d. 2000. identity and ecology in arctic siberia: the number one reindeer brigade. oxford: oxford university press. apsh 1980. aktual’nye problemy sel’skogo hozjajstva. (current agricultural problems.) moscow: selskoye khozaystvo. babuškin [babushkin] a.i. 1930. bol’šezemel’skaja tundra. (bol’šezemel’skaja tundra.) syktyvkar: izdatelstvo komi obstatotdela. dwyer m.j. 2006. komi reindeer herding: mobility and land use in a changing natural and social environment. phd thesis, university of cambridge. fondahl g.a. 1989. native economy and northern development: reindeer husbandry in transbaikalia. phd thesis, university of california, berkeley. golovnev a.v. & oshirenko g. 1999. siberian survival: the nenets and their story. london: cornell university press. gray p.a. 2005. the predicament of chukotka’s indigenous movement. post-soviet activism in the russian far north. cambridge: cambridge university press. gray p. & stammler f. 2002. sibirien zwischen kollaps und kontinuität. (siberia between collapse and continuity.) max planck forschung 2, 54–61. habeck j.o. 2003. what it means to be a herdsman: the practice and image of reindeer husbandry among the komi of northern russia. phd thesis, university of cambridge. habeck j.o. 2005. what it means to be a herdsman: the practice and image of reindeer husbandry among the komi of northern russia. münster: lit verlag. ige (institute of geography and economy [ždanov leningrad state university] & soviet union academy of sciences) 1964. atlas komi assr. (atlas of the komi autonomous soviet socialist republic.) moscow: glavnoje upravlenije geodezii i kartografii. islavin v. 1847. samoedy v domašnem i obščestvennom bytu. (samoyeds in their private and public life.) st. petersburg: izdatelstvo ministerstva gosudarstvennykh imushestv. istomin k.v. 2000. living in chum. social relations and personal behavioural strategies among komi reindeer herders. pro ethnologia 10, 50–76. istomin k. 2004. ètnoèkologičeskije aspekty komi-ižemskogo olenevodstva. (ethno-ecological aspects of izhma-komi reindeer herding.) phd thesis, komi science centre, syktyvkar. jernsletten j.-l. & klokov k. 2002. sustainable reindeer husbandry. tromsø, norway: centre for saami studies, university of tromsø. kercelli [kertselli] s.v. 1911. po bol’šezemel’skoj tundre s kočevnikami. (a trip with nomads across the bol’šezemel’skaja tundra.) archangelsk: gubernskaya tipografiya. king a. 2003. social security in kamchatka: rural and urban comparisons. in c. hann (ed.): the postsocialist agrarian question. pp. 391–418. münster: lit verlag. klokov k. (ed.) 2004. semejnyye osnovy olenevodčeskopromyslovogo hozajstva. (the family foundations of the reindeer herding and hunting economies.) tromsø, norway: saami research centre, university of tromsø. klokov k.b. & šustrov d.n. 1999. tradicionnoje olenevodčesko-promyslovoje hozajstvo taimyra. (traditional reindeer herding and hunting economy of taimyr.) moscow: izdatel’stvo spbu. kna (komi national archive). various years. folder 4: files 2576, 3794, 4859 and 4895. sovetskaya ulitsa 26, syktyvkar, komi republic, russia. kolegov m.a. 2004. resource and production opportunities of reindeer husbandry in the komi republic. syktyvkar: information centre for nature resources and environment protection of the komi republic. konakov n.d. & kotov o.v. 1991. ètnoareal’nye gruppy komi. formirovanie i sovremennoe sostojanie. (komi dispersion. their origin and current state.) moscow: nauka. konakov n.d. & žerebcov i.l. 1994. tradicionnaja kul’tura komi. (the traditional culture of the komi.) syktyvkar: komi knizhnoye izdatelstvo. konstantinov y. 2002. soviet and post-soviet reindeer-herding collectives: transitional slogans in murmansk region. in e. kasten (ed.): people and the land. pathways to reform in post-soviet siberia. pp. 171–188. berlin: dietrich reimer verlag. konstantinov y. & vladimirova v. 2006. the performative machine: transfer of ownership in a northwest russian reindeer herding community (kola peninsula). nomadic peoples 10, 166–186. kovalev s.a. & šapošnikov s.v. (eds.) 1977. dinamika sistem rasselenija: sbornik statei. (dynamics of the settlement system: a collection of articles.) moscow: economica. krupnik i.i. 1976. stanovlenie krupnotabunnogo olenevodstva u tundrovyh nencev. (the rise of large-herd reindeer herding among the tundra nenets.) sovetskaja ètnografija 2, 57–69. krupnik i.i. 1989. arktičeskaja ètnoèkologija. (arctic ethno-ecology.) moscow: nauka. krupnik i. 2000. reindeer pastoralism in modern siberia: research and survival in the time of crash. polar research 19, 49–56. kssc (komi state statistical committee) 2005. sostojanie životnovodčeskoj otrasli sel’skogo hozajstva v respublike komi v 1990–2003 godah. analitičeskaja zapiska kgsk. (the situation in the animal breeding sector of agriculture in the komi republic 1990–2003. analytical note of the komi state statistical committee.) syktyvkar: komi state statistical committee. ma (ministry of agriculture) 1982. komi assr reindeer herding map of bol’šaja inta. document no. 7178. syktyvkar: ministry of agriculture. muhačev [muhachev] a.d. 1990. olenevodstvo. (reindeer herding.) moscow: agropromizdat. nuvano v.n. 2006. traditional routes of herd’s movements in east and central chukotka. in k. ikeya (ed.): chukotka komi reindeer herders’ mobility and land use m.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors296 studies 4. the chukchi culture. pp. 109–122. osaka: chukotka studies committee. pavlov p.n. 2003. kommentarij k federal’nomu zakonu “o territotijah tradicionnogo prirodopol’zovanija korennyh maločislennyh narodov severa, sibiri i dal’nego vostoka rossijskoj federacii”. (comments on the federal law “on the territories of traditional land-use by the aboriginal small peoples of the north, siberia and far east of the russian federation”). in g.v. gruza & v. m. makeev (ed.) vse o severe. (everything about the north.) vol. 2. pp. 199–217. st. petersburg: nord-ost-norma. roščevskij [roshchevsky] m.p., vaneev a.e. & timonin n.i. (eds.) 1999. respublika komi: ènciklopedija. (encyclopaedia of the komi republic.) vol. 1. syktyvkar: komi nauchnyy tsentr, uralskoje otdelenije rossijskoj akademii nauk. sergeev m.a. 1955. nekapitalističeskij put’ razvitija malyh narodov severa. (the non-capitalist way of development for the small peoples of the north.) moscow: nauka. shindler d.l. 1991. theory, policy and the “narody severa” (northern people). anthropological quarterly 64(2), 68–79. slezkine y. 1994. arctic mirrors: russia and the small people of the north. new york: cornell university press. smetanin a.f. & savel’eva e.a. (eds.) 2004. istorija komi. (the history of komi.) vol. 2. syktyvkar: komi knizhnoye izdatelstvo. stammler f. 2005: reindeer nomads meet the market: culture, property and globalisation at the “end of the land”. münster: lit verlag. stammler f. & ventsel a. 2003. between neo-liberalism and dirigisme: approaches to reindeer herding in yamal and sakha. in c. hann and the property relations group (eds.): the postsocialist agrarian question. property relations and the rural condition. pp. 321–362. münster: lit verlag. syrovatskij [syrovatsky] d.i. 1975: sostavlenie maršrutov—osnova organizacii olen’ih pastbišč. (route drawing is the foundation for reindeer pastures’ use.) bjulljuten’ naučno-tehničeskoj informacii nii sel’skogo hozajstva krajnego severa 9, 16–17. took r. 2003. running with reindeer: encounters in russian lapland. boulder, co: westview press. tuisku t. 2002. transition period in the nenets autonomous okrug: changing and unchanging life of nenets people. in e. kasten (ed.): people and the land. pathways to reform in post-soviet siberia. pp. 189–206. berlin: dietrich reimer verlag. vakhtin n. 1994. native peoples of the russian north. in minority rights group (ed.): polar peoples: self-determination and development. pp. 29–80. london: minority rights publications. ventsel a. 2005. reindeer, rodina and reciprocity. kinship and property relations in a siberian village. berlin: lit verlag. vitebsky p. & wolfe s. 2001. the separation of the sexes among siberian reindeer herders. in s. tremayne & a. low (eds.): women as “sacred custodians” of the earth. pp. 81–94. oxford: berg. zabrodin v.a. 1980. soveršenstvovanie tehnologii vedenija olenevodstva. (improvement of the reindeer herding technology.) in a.d. muhačev [mukhachev] (ed.): puti intensivnogo razvitija olenevodstva na krajnem severe. (the ways of intensive development of reindeer herding in the far north.) pp. 3–9. novosibirsk: sibirskoye knizhnoye izdatelstvo. žerebcov [zherebcov] l.n. 1982. istoriko-kul’turnye vzajmootnošenija komi s sosednimi narodami. (historical and cultural inter-relations between komi and neighbouring peoples.) moscow: nauka. komi reindeer herders’ mobility and land usem.j. dwyer & k.v. istomin polar research 28 2009 282–297 © 2009 the authors 297 research article variable respiration rates of incubated permafrost soil extracts from the kolyma river lowlands, north-east siberia joanne k. heslopa, sudeep chandraa, william v. sobzcakb, sergey p. davydovc, anna i. davydovac, valentin v. spektord & katey m. walter anthonye aaquatic ecosystems analysis laboratory, department of natural resources and environmental science, university of nevada, reno, nv, usa; bdepartment of biology, college of the holy cross, worcester, ma, usa; cnorth-east science station, pacific institute of geography, far east branch of russian academy of sciences, cherskiy, russian federation; dmelnikov permafrost institute siberian branch, russian academy of sciences, republic of sakha (yakutia), yakutsk, russian federation; ewater and environmental research center, university of alaska fairbanks, fairbanks, ak, usa abstract thawing permafrost supplies dissolved organic carbon (doc) to aquatic systems; however, the magnitude, variability and fate of this doc is not well constrained. our objective was to examine doc respiration from seasonally thawed and near-surface (<1.5 m) permafrost soils collected from five locations in the kolyma river basin, north-east russia. we measured soil organic carbon (oc) content, water-soluble macronutrients (doc, nh4, po4) and the heterotrophic respiration potentials of soil extract doc in five-day laboratory incubations. doc concentrations ranged from 2.8 to 27.9 mg l−1 (n = 14). carbon respiration was 0.03–0.47 mg c (n = 16) and 8.7–31.4%, total doc (n = 14). while doc concentration was a function of soil oc concentration, we did not find a relationship between c respiration and soil oc or doc concentrations. respiration was highest in the top active layer, but varied widely among sites, and lowest at the bottom of the active layer. respiration from yedoma varied across sites (0.04–0.47 mg c respired, 8.7–31.4% total doc). despite the small sample size, our study indicates near-surface soils and permafrost are spatially variable in terms of both soil oc content and c respiration rates, and also that oc contents do not predict c respiration rates. while a larger sample size would be useful to confirm these results at broader geographic scales, these initial results suggest that soil oc heterogeneity should be considered in efforts to determine the fate of soil oc released from permafrost-dominated terrestrial ecosystems to aquatic ecosystems following permafrost thaw. keywords arctic; carbon export and processing; yedoma; climate change; greenhouse gas production abbreviations bod: biological oxygen demand; doc: dissolved organic carbon; oc: organic carbon; se: standard error; nh4-n: ammonium; po4-p: orthophosphate perennially frozen ground (permafrost) contains a vulnerable c pool susceptible to warming and thaw (zimov, schuur et al. 2006; schuur et al. 2008; schuur et al. 2015). permafrost covers 22% of the northern hemisphere (brown et al. 1998) and contains an estimated 1140–1580 pg of oc – approximately half of the world’s belowground oc (hugelius et al. 2014; schuur et al. 2015). temperatures in the arctic have increased an average of 0.6°c per decade over the last 30 years, which is twice as fast as the global average (stocker et al. 2013). this climate warming triggers the release of permafrost oc via permafrost thaw and erosion, exporting large amounts of terrestrial c to aquatic environments (striegl et al. 2005; frey & mcclelland 2009; vonk et al. 2013; cory et al. 2014; larouche et al. 2015) and making previously frozen oc from a range of soil depths available for microbial decomposition (goulden et al. 1998; dutta et al. 2006; schuur et al. 2008; tarnocai et al. 2009; vonk et al. 2013; mann et al. 2014). thaw depths of the seasonally thawed active layer rapidly respond to warming air temperatures (hinkel & nelson 2003; frauenfeld et al. 2004) and active layer thicknesses are projected to increase as a result of climate warming, releasing fractions of previously frozen oc from near-surface permafrost (zhang et al. 2005; frey & mcclelland 2009). deepening active layers are projected to increase the degree of interaction between soils and water (neff et al. 2006; battin et al. 2008; davydov et al. 2008; frey & mcclelland 2009), allowing water-soluble fractions of recently thawed oc to dissolve into soil water. the permafrost underlying the active layer prevents the subsurface flow from percolating deeper (wickland et al. 2007), facilitating soil water export which, in turn, may lead to an increase in the export of permafrost oc to inland waters (vonk et al. 2013; spencer et al. 2015). dissolved fractions of terrestrial oc can fuel microbial respiration and the production of greenhouse gases (ågren et al. 2008; battin 2008; wang et al. 2014). when terrestrial doc enters aquatic systems, a portion is further mineralized to contact joanne k. heslop jheslop@alaska.edu water and environmental research center, university of alaska fairbanks, po box 5860, fairbanks, ak 99775, usa. supplemental data for this article can be accessed here. polar research, 2017 vol. 36, 1305157 https://doi.org/10.1080/17518369.2017.1305157 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. https://doi.org/10.1080/17518369.2017.1305157 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1305157&domain=pdf co2, which can escape to the atmosphere or be assimilated by plants and algae living in the water (tao & lin 2000; vonk et al. 2013). other potential fates of terrestrially derived doc in aquatic systems are export via transportation, sequestration via flocculation and sedimentation, or bioassimilation by microbes and organisms through aquatic food webs (cole et al. 2007; mcguire et al. 2010). up to 40% (210–456 pg c; strauss et al. 2013; walter anthony et al. 2014) of permafrost soil oc is stored in ice-rich loess-dominated soils referred to as yedoma. formed in unglaciated regions of siberia, alaska, and north-west canada during the late pleistocene (solov’ev 1959; zimov, schuur et al. 2006; kanevskiy et al. 2011), yedoma soils are thick (<50 m) silt-dominated deposits rich (2–30%) in oc for mineral soils (schirrmeister, grosse et al. 2011). yedoma is extensive in north-east siberia, where it underlies an area of over 1 000 000 km2 and averages 25 m in thickness (romanovskij 1993; zimov, schuur et al. 2006). evidence shows yedoma deposits are currently thawing (romanovsky et al. 2010), but the potential for greenhouse gas production by microbial decomposition of organic matter in thawed yedoma soils has been studied with limited geographic and spatial scope (zimov et al. 1993; zimov et al. 1997; dutta et al. 2006; walter et al. 2007; lee et al. 2012; mann et al. 2012; knoblauch et al. 2013; vonk et al. 2013). ancient (20,000–35,800 years old) doc from yedoma soils has found to be more biolabile than arctic stream, river and permafrost doc from nonyedoma systems (vonk et al. 2013; mann et al. 2014; drake et al. 2015; spencer et al. 2015). however, it has been suggested that the oc content of yedoma soils is not evenly distributed across geographic space and stratigraphic layers (dutta et al. 2006; zimov, davydov et al. 2006; zimov, schuur et al. 2006; schirrmeister, grosse et al. 2011). respiration rates of ancient (21 700 years old) doc from a single yedoma outcrop in the kolyma river basin, northeast siberia, were found to be 1.3–1.6 times higher than those of modern doc collected from different sites in the same yedoma-dominated watershed (mann et al. 2014). this suggests that location and particular permafrost soil forming processes could affect the magnitude of potential c release from thawing permafrost. in order to estimate the potential magnitude of gas production from thawing yedoma, the soil oc content of which is geographically variable, it is important to gain a better understanding the potential respiration rates of water-soluble soil oc collected from a wide distribution of sites. water-soluble oc derived from soil extracts is representative of the most mobile and labile fractions of soil oc (ohno et al. 2009; he et al. 2011) which can be readily utilized by microbes (matzner & borken 2008; wang et al. 2014). therefore, in permafrost-dominated regions, examining c respiration rates from soil extracts collected from a variety of environments with varying amounts of disturbance and available oc provides a useful perspective as to how climate change may alter c cycling dynamics in these systems. the objective of this study was to quantify the variability of water-soluble soil oc respiration potentials from 16 active layer and thawed shallow (<1.5 m) permafrost soils from five different landscapes in the kolyma river basin, north-east siberia, russia using laboratory incubations of soil extracts mixed with river water as a proxy for water-soluble permafrost oc biolability in inland waters. this study was performed as part of the national science foundation’s polaris project, a summer research programme for undergraduate students. despite a small sample size and limited geographic scope, we hypothesized that the c respiration potentials of incubated extracts would be directly related to soil oc content and that the oc contents and c respiration potentials would be spatially variable on scales of both stratigraphic layers and geographic locations. materials and methods study site and sample collection the kolyma river basin is the largest arctic river basin entirely underlain by continuous permafrost, spanning approximately 650 000 km2 across northeast siberia (vtyurin 1975; griffin et al. 2011; holmes et al. 2012). the kolyma river basin is largely underlain by yedoma permafrost and the doc in its rivers shifts from modern (δ14c > 100‰) c in the spring to older (δ14c < 0‰) c in the fall, suggesting the origin of the doc transitions from shallow to deeper soils as the active layer seasonally deepens (neff et al. 2006). we collected soil samples at five sites in the kolyma river basin in july 2010 (table 1, fig. 1). the sites were selected to be representative of various yedoma-dominated landscapes in the mixed boreal forest region of the kolyma river watershed. duvyanni yar is a yedoma outcrop, about 30–40 m tall, exposed by the kolyma river through thermokarst and thermoerosion. shuchi lake and tube dispenser lake are first generation thermokarst (thaw) lakes formed in thick yedoma permafrost (>40 m) within 5 km of the town of cherskii. the rodinka soil pit (160 m asl) was dug in the top of finish creek valley on the south-west flank of rodinka mountain, where the yedoma horizon is relatively thin (ca. 15 m), near faded thermokarst and solifluction features. the bulldozer site refers to a lower elevation slope beneath rodinka mountain, 60 m asl. the bulldozer site is a field of residual 2 j.k. heslop et al. thermokarst mounds (baydzherakhs) where the surface 4 m of the soil profile have thawed following bulldozer excavation and removal of the surface organic horizon and active layer (60–80 cm) in 2003. the surface at our study soil profiles at duvyanni yar and shuchi lake had not been disturbed previously. in contrast, bulldozer and natural thermokarst activity had removed much of the overlying peat prior to our sampling at the tube dispenser lake, rodinka and bulldozer study sites. we report surface vegetation species at each site in supplementary table s1. with the exception of the duvyanni yar site, none of the sample sites exhibited signs of cryoturbation (supplementary fig. s1) we delineated soil profiles at each sample location from either cross-sectional permafrost exposures or soil pits (table 1). we determined the thickness of the active layer at these sites by probing to the depth of permafrost at the time of sampling (july), which was prior to the maximum thickness of seasonally thawed active layer (september). samples to examine soil characteristics (gravimetric soil moisture, bulk density and organic matter content) were collected in ca. 10 cm intervals at each soil profile. samples for soil extract chemistry and respiration experiments were collected from four depths along soil profiles representative of different potential regions for soil– water interactions. the top (10–15 cm) and bottom (30–50 cm) of the seasonally thawed active layer, determined using july thaw depths, represent regions of near-surface soils which presently experience seasonal freeze–thaw cycles that process and degrade oc. the transient layer (70–100 cm), consisting of permafrost soils thawed approximately 7000–5000 years ago, during the holocene thermal optimum that subsequently re-froze under colder climate conditions (sher et al. 1979; schirrmeister, kunitsky et al. 2011), represents near-surface soils that do not thaw seasonally today but may seasonally thaw in a future warmer climate. the presence of massive ice wedges adjacent to our sampling depths indicates that yedoma permafrost sampled at depths greater than 100 cm below the ground surface and representing older pleistocene-aged permafrost has not thawed during the holocene. these samples represent near-surface permafrost soils where the oc has not been previously degraded by freeze– thaw cycles during the holocene. the depth of the boundary between the transient layer and yedoma permafrost was determined by assuming the tops of visible ice wedges represented the maximum historic active layer thaw depth at that site. in total we collected 16 (four top active layer, four bottom active layer, four transient layer and four yedoma; table 2) samples for soil extract chemistry and respiration experiments. each of these samples was divided into two subsamples and stored (holding time ≤10 days) in the dark at 15°c prior to analysis. soil characteristics we analysed all of the soil characteristics samples (n = 44) and one of each soil extract chemistry and respiration experiment subsample pair (n = 16) for gravimetric soil moisture, bulk density and organic matter content. gravimetric water content was determined as the difference in mass between the soil at field moisture and the oven-dried (105°c for 48 hours) soil over the mass of the oven-dried soil. bulk density was measured as the dry soil mass divided by the soil subsample volume. we determined soil organic matter content by calculating the mass difference between the oven-dried and ashed (400°c for 4 hours) soil. in our calculations we assumed soil oc content was 50% of soil organic matter mass (pribyl 2010). grain-size distribution was determined using standard hydrometer methods (gost 2008), with results presented in supplementary table s2. soil extract chemistry soil extracts were prepared from the second of each respiration experiment soil subsample pair (n = 16) table 1. location, sampling dates, profile delineation method, total depth of profile, depth to the permafrost table and prior observable disturbance at the time of sampling for the soil profiles in this study. see supplementary table s1 for surface vegetation cover at each site. site lat. north long. east date sampled (2010) profile delineation method profile depth (cm) depth to permafrost table (cm) prior surface disturbance shuchi lake ridge 68.748° 161.384° 8 july soil pit 93 55 none duvyanni yar 68.630° 159.154° 20 july thermokarst exposure 370 35 none bulldozer site 68.698° 161.539° 9 july thermokarst exposure 80 –a top 60–80 cm removed by bulldozer, 2003 tube dispenser lake 68.897° 161.407° 12 july soil pit 190 70 thermokarst activity rodinka 68.724° 161.588° 14 july thermokarst exposure 190 103 thermokarst activity and thermal erosion a permafrost table was not reached in this profile. polar research 3 figure 1. (a) map showing the five soil sample sites in the kolyma river basin, north-east siberia, russia, and (b–f) photographs showing locations of the sample sites, marked using white triangles. surface vegetation data for each site are presented in supplementary table s1. (b) the bulldozer site, located in the rodinka mountain piedmont, is in a field of residual thermokarst mounds (baydzherakhs) with the kolyma and panteleikha rivers floodplain visible in the distance. (c) the tube dispenser lake profile was delineated near exposures of melting ice wedges on the southern slope of the tube dispenser lake, a thermokarst lake. (d) the rodinka samples, from a site located on the lower slope of rodinka mountain, were collected near faded thermokarst and solifluction forms in the finish creek valley. the flourishing violet, yellow and white flowers indicate the site is in the first succession stadium following completion of active thermokarst and thermal erosion. (e) the shuchi lake ridge site is located within a ‘drunken forest,’ formed as the yedoma ice complex degrades and sediment slides into the southern wall of the thermokarst shuchi lake. (f) the duvyanni yar samples were collected from the duvyanni yar thermokarst and thermoerosional exposure, cut by the kolyma river, of the late pleistocene ice complex. photographs by v.v. spektor. 4 j.k. heslop et al. by vigorously mixing a 100 g subsample of soil at field moisture with 1 l deionized water for 30 minutes. the extract was filtered through a precombusted (450°c for 4 hours) glass microfibre filter (0.7 μm, whatman gf/f) to remove particulate organic matter and analysed for ammonium (nh4-n; detection limit 5 μg l−1) using a fluorometric method (taylor et al. 2007) and soluble reactive phosphorous (po4-p; detection limit 10 μg l−1) using the molybdenumblue method (rigler 1966). doc content was quantified using a shimadzu toc-v using established protocols (mann et al. 2012). we calculated the fraction of water soluble oc as the ratio between the mass of doc extracted and the mass of total oc in the bulk soil utilized to make the extract. respiration experiments we conducted heterotrophic respiration experiments on permafrost soil extracts mixed with water from the panteleikha river as a proxy for water-soluble oc bioavailability in inland waters. the panteleikha river drains an area of 1500 km2 and is a tributary to the kolyma river. panteleikha river water was obtained from about 1 m depth on 27 july 2010. we analysed a subsample of river water for doc, nh4-n and po4-p using the methods described in the previous section. respiration potentials were measured by incubating 60 ml of the prepared soil extract with 240 ml of unfiltered panteleikha river water within standard 300 ml bod bottles (wheaton). duplicate experimental incubation vials were prepared for each of the 16 soil extract samples. two bod bottles containing 300 ml unfiltered panteleikha river water were prepared as an experimental control. all incubation vials were tightly sealed and maintained in the dark at 20° c, the approximate temperature of the panteleikha river’s near-surface water in july. we calculated biological oxygen (o2) demand using standard methods as the loss of dissolved o2 over a five-day period (greenberg et al. 1992). we determined dissolved o2 concentrations in the bottles using a benchtop bod o2 probe (ysi 556; accuracy ± 0.2 mg l−1); none of the bottles reached anoxia within the five-day period. oxygen consumption was converted to c respiration by assuming that all dissolved o2 loss was due to aerobic respiration and each unit loss in o2 corresponded to a unit production of carbon dioxide (co2). the calculated co2 production over the incubation period was multiplied by the ratio of carbon’s atomic mass to oxygen’s atomic mass (0.375) to determine the mass of c respired in each incubation vial. we report the c respiration of each sample in terms of: total c respired (mg), net c respired from the soil extract (mg), the mass of c respired per gram soil oc (mg c g oc−1) and the fraction of total doc respired (%). total c respiration from the bod bottle is reported as cumulative c respired from both the river water and the soil extracts during the five-day bod incubation period. net c respiration from the soil extract is reported as the total c respiration from the bod bottle minus the mean c respiration measured in the river water controls. the mass of c respired per gram soil oc was calculated by dividing the net c respiration from the soil extract by the mass of oc in the soil used to prepare the extract. we calculated the fraction of doc respired by dividing the total c respiration by the measured amount of total doc within the bod bottle. all respiration data are table 2. soil sample depths, bulk density, field moisture content, oc content, water extractable oc fractions and measured doc, nh4-n and po4-p concentrations for all soil extracts and panteleikha river water from different sampling sites and stratigraphic layers in the kolyma river basin. each line in the table represents one soil sample collected and processed as described in the materials and methods section. soil properties soil extract chemistry sample site stratigraphic layera depth (cm) dry bulk density (g cm−3) field moisture (%) oc content (%) fraction water extractable oc (%) doc (mg l−1) nh4-n (μg l−1) po4-p (μg l−1) shuchi lake ridge tal 15 0.78 35 13.0 0.33 27.85 –b –b bal 50 0.60 18 1.5 0.45 5.55 24.83 33.79 tl 90 0.45 19 1.5 0.23 2.82 2608 36.67 duvyanni yar tal 15 0.97 65 20.5 0.27 19.15 118.0 7.29 bal 35 0.49 22 2.5 0.15 3.01 255.1 59.30 tl 70 0.22 48 4.0 1.06 22.11 360.0 23.47 pp 150 0.56 36 2.5 1.02 16.37 4573 10.26 bulldozer site pp 80 0.82 10 1.5 0.68 9.13 74.11 47.49 tube dispenser lake tal 10 0.74 24 1.0 1.19 9.03 87.30 bdlc bal 30 0.74 24 1.0 –b –b –b –b tl 70 0.74 47 1.5 –b –b –b 28.61 pp 110 0.35 36 1.5 0.84 8.10 249.8 90.37 rodinka tal 15 0.75 12 2.5 0.23 5.08 –b –b bal 40 0.67 20 2.5 0.36 7.28 81.95 22.88 tl 100 0.70 38 2.5 1.78 27.66 –b 28.61 pp 120 1.04 38 3.0 1.40 25.95 533.4 22.57 panteleikha river river water ca. 100 n/a n/a n/a n/a 4.83 50.00 310.0 a tal: top active layer; bal: bottom active layer; tl: transient layer; pp: pleistocene permafrost. b parameter was not measured. polar research 5 presented as mean ± se together with a reported sample size, where n represents the number of soil extract samples. an n value of 1 represents the mean of duplicate laboratory incubation vials containing extract from a single field soil sample. statistics all statistical analyses were conducted using matlab (r2013a student version) software. soil oc contents and all soil extract data (nh4-n, po4p, doc, net c respiration, c respiration g soil oc−1, % doc respired) were tested for normal distribution using the jarque–bera test. the data for doc, net c respiration and % doc respired were found to be consistent with a normal distribution at the α = 0.05 level. data for soil oc, soil extract nh4-n and po4-p concentrations, and c respiration g soil oc−1 were not consistent with a normal distribution at the α = 0.05 level; these variables were log-transformed to improve normality. since half of our data parameters were found to be inconsistent with a normal distribution, we determined the statistical significance of differences in soil oc and extract parameters between soil layers and sampling sites using the nonparametric mann–whitney u-test. we determined all correlations using spearman’s rank correlation coefficients. both the differences and correlations were considered statistically significant when p ≤ 0.05 (α = 0.05 confidence level). finally, we conducted forward stepwise multiple linear regressions to examine how well our tested soil (log[oc]) and extract (doc, log[nh4-n], log[po4-p]) parameters predicted the measured c respiration (net c respiration, log[c respiration g soil oc−1] and % doc respired). terms were added to the stepwise regression models using the standard sse criterion. results soil characteristics soil dry bulk density ranged from 0.21–1.13 g cm−3 (median 0.70 g cm−3, mean 0.67 ± 0.23 g cm−3, n = 44) and gravimetric water content ranged from 7.2 to 70.7% moisture (median 24.0%, mean 28.1 ± 16.7%, n = 45; supplementary fig. s2). soil bulk oc content ranged from 1 to 20.5% by mass (median 1.7%, mean 2.7 ± 3.3% oc, n = 46). soils from duvyanni yar (1.7–20.3% oc, median 2.9%, mean 4.9 ± 5.5%, n = 11) and shuchi lake ridge (1.2–12.9% oc, median 1.2%, mean 2.7 ± 4.1%, n = 8), the two sites which had not experienced prior disturbance, had higher levels of bulk soil oc (p = 0.021 and 0.001, respectively) compared to other sampling sites. there were no additional statistically significant differences in soil characteristics between sampling sites or soil stratigraphic layers. river water and soil extract chemistry river water from the panteleikha river had initial nutrient concentrations of 50.0 ± 5 μg l−1 nh4-n, 310.0 ± 10 μg l−1 po4-p, and 4.83 mg l −1 doc (table 2). ammonium (nh4-n) concentrations extracted from the soil samples ranged from 24.8 to 4573 μg l−1 nh4-n (median 250 μg l −1, mean 747 ± 437 μg l−1, n = 11). extracted soluble reactive phosphorous (po4-p) concentrations ranged from 7.3 to 90.4 μg l−1 po4-p (median 28.6 μg l −1, mean 31.7 ± 6.4 μg l−1, n = 12). doc concentrations in the soil extract varied by an order of magnitude, ranging from 2.8 to 27.9 mg l−1 (median 9.1 mg l−1, mean 13.5 ± 2.5 mg l−1, n = 14). soils with higher oc contents extracted more doc (r = 0.58, p = 0.029). fractions of water soluble oc in our extracts ranged from 0.15 to 1.78% (median 0.57%, mean 0.71 ± 0.14% oc, n = 14). there were no statistically significant differences in soil extract chemistry between sampling sites or soil stratigraphic layers. full river water and soil extract chemistry results are shown in table 2. carbon respiration total c respiration during the five-day incubation period ranged from 0.17 to 0.67 mg c (median 0.28 mg, mean 0.33 ± 0.08 mg, n = 16; table 3). the fraction of total doc (river water doc plus soil extract doc) respired during the incubation period ranged from 8.9 to 31.4% (median 17.8%, mean 18.2 ± 1.7%, n = 14). soil extract respiration ranged from −0.03 to 0.47 mg c (median 0.08 mg, mean 0.13 ± 0.08 mg, n = 16) and −0.42 to 5.21 mg c g soil oc−1 (median 0.62 mg c g soil oc−1, mean 1.32 ± 1.77 mg c g soil oc−1, n = 16). extract samples from the shuchi lake ridge bottom active layer, duvyanni yar bottom active layer and tube dispenser lake transitional layer respired less c than the river water control. overall, the bottom active layer had lower c respiration potentials (total c respired and c respired from soil extract) than the other stratigraphic layers (p = 0.012 for both; fig. 2). there were no statistically significant differences in c respiration between sampling sites (supplementary fig. s3). full c respiration results are shown in table 3. correlation analyses did not show any statistically significant relationships between c respiration, soil oc contents and extract doc, nh4-n or po4-p concentrations. forward stepwise multiple linear regression analyses revealed that the mass of soil extract c respired (mg) and the fraction of total doc respired (%) could be estimated by the log6 j.k. heslop et al. transformed nh4-n concentrations in the soil extracts (p = 0.046 and 0.043, respectively; table 4). carbon respiration in terms of c respired per g soil oc was not predicted by any measured parameters in the final linear model. complete data for the linear regression models are presented in table 4. discussion our results indicate that soils in the kolyma river basin, north-east siberia, are spatially variable in terms of soil oc content. soils from duvyanni yar and shuchi lake ridge had significantly (p < 0.05) higher oc contents compared to the other sampled sites. we hypothesize this is because much of the surface vegetation has remained undisturbed, allowing modern plants and roots to provide greater fresh oc input at these two sites. the observed variance in yedoma (pleistocene permafrost) oc content across sites (1.5–3.0% oc) suggests that soil oc is unevenly distributed across the yedoma-permafrost-dominated landscape. this outcome would be expected given that, even within a single site, soil oc content can vary by an order of magnitude throughout the vertical profile of tens of metres because of palaeoenvironmental differences during the pleistocene and holocene (tarnocai et al. 2009; schirrmeister et al. 2011a). samples collected from the bottom active layer had lower mean c respiration rates than the other stratigraphic layers in our study (p = 0.012). soils in the table 3. mass of initial doc in the bod bottles, the initial doc partitioning between soil extract doc and river water doc, the amount of carbon (c) respired during the five-day incubation ± se between duplicate bottles, c respired from the soil extracts (net c respiration – river water control), c respired per g soil oc (c respired from soil extract/mass soil oc used to make the extract), the fraction of total doc (river doc + extract doc) respired and the effect of the soil extract on c respiration. the effect of the soil extract on c respiration was determined as positive (+) or negative (−) when c respiration from the soil extracts was higher or lower than the river water control, respectively. doc c respiration sample site stratigraphic layera doc contribution from soil extract (mg c) doc contribution from river water (mg c) net initial doc in bod bottle (mg c) total c respired in bod bottle (mg c) c respired from soil extract (mg c) c respired per g soil oc (mg c g oc−1) fraction of total doc respired (%) effect of soil extract on c respirationc panteleikha river river water n/a 1.45 1.45 0.20 ± 0.01 n/a n/a 13.82 n/a shuchi lake ridge tal 1.67 1.16 2.83 0.50 ± 0.05 0.30 0.59 17.48 + bal 0.33 1.16 1.49 0.17 ± 0.02 −0.03 −0.41 11.34 – tl 0.17 1.16 1.33 0.35 ± 0.03 0.15 2.06 26.02 + duvyanni yar tal 1.15 1.16 2.31 0.44 ± 0.02 0.24 0.56 19.17 + bal 0.18 1.16 1.34 0.19 ± 0.00 −0.01 −0.09 14.05 – tl 1.33 1.16 2.49 0.45 ± 0.03 0.25 2.00 18.12 + pp 0.98 1.16 2.14 0.67 ± 0.27 0.47 4.90 31.35 + bulldozer site pp 0.55 1.16 1.71 0.24 ± 0.01 0.04 0.50 14.33 + tube dispenser lake tal 0.54 1.16 1.70 0.36 ± 0.01 0.16 3.51 20.99 + bal –b 1.16 –b 0.24 ± 0.01 0.04 0.88 –b + tl –b 1.16 –b 0.18 ± 0.01 −0.02 −0.42 –b – pp 0.49 1.16 1.65 0.50 ± 0.02 0.30 5.21 30.28 + rodinka tal 0.30 1.16 1.46 0.30 ± 0.09 0.10 0.76 20.62 + bal 0.44 1.16 1.60 0.20 ± 0.01 0.00 0.00 12.82 – − tl 1.66 1.16 2.82 0.26 ± 0.13 0.06 0.66 9.28 + pp 1.56 1.16 2.72 0.24 ± 0.02 0.04 0.36 8.86 + a tal: top active layer; bal: bottom active layer; tl: transient layer; pp: pleistocene permafrost. b parameter was not measured. c + increased respiration; – suppressed respiration; – − no change. figure 2. (a) carbon respiration separated by site and (b) by stratigraphic layer. the top graphs show the mass of c respired from the soil extracts (mg c); the middle graphs show the mass of c respired per g soil oc (mg c g oc−1); the bottom graphs show the fraction of total doc respired during the five-day incubation period (%). polar research 7 bottom active layer currently experience seasonal freeze–thaw cycles, which degrades soil oc and promotes increased water-soluble oc release (wang et al. 2014). although soils in the top active layer also experience annual freezing and thawing, the top active layer receives inputs of fresh, labile oc from modern plants which are densely rooted in this layer, while soils in the bottom active layer presumably receive lower inputs of fresh organic matter from modern plants. in addition, deeper active layer depths in late summer cause increased water residence times in the bottom active layer compared to the top active layer, which increases soil–water interaction and can potentially facilitate oc dissolution and export (neff et al. 2006; wickland et al. 2007; frey & mcclelland 2009). however, it is important to note that in natural systems this process is highly watershed-dependent and, depending on local environmental and permafrost conditions, increased soil–water interaction can also lead to the sorption of doc to mineral soils (mcdowell & wood 1984; neff & asner 2001; frey & mcclelland 2009). the c respiration rates of shallow yedoma (pleistocene silt-dominated permafrost) in our study were highly variable by site. the yedoma soil extract from duvyanni yar respired 3.4 times more c than the averaged yedoma extracts from the tube dispenser lake, rodinka and bulldozer sites, although its soil oc content was on average only 1.3 times higher. this suggests that the yedoma oc was more bioavailable at the duvyanni yar site and yedoma organic matter quality is not homogeneous across the kolyma river basin, which concurs with the findings of mann et al. (2014) concerning the spatial variability of doc biolability in the same watershed. we did not observe statistically significant differences in c respiration potentials when comparing the transient layer and the yedoma. we had hypothesized that extracts from the transient layer would respire less c than extracts from the pleistocene permafrost because the most labile fractions of its oc pool had been previously degraded by freeze–thaw cycles and microbial respiration during the holocene thermal optimum (sher et al. 1979; schirrmeister et al. 2011b; vonk et al. 2013; wang et al. 2014). while the lack of a statistically significant difference in c respiration rates may be due to our small sample size, it is also possible that near-surface yedoma with the potential to thaw from deepening active layer thicknesses may not have significantly higher proportions of bioavailable oc when compared to the overlying shallow transient layer permafrost. we observed lower respiration rates in 25% of vials containing soil extracts compared to the control vials containing only river water (table 3), suggesting that the soil extracts in these samples may contain inhibitory organic compounds that reduce doc decomposition in aquatic systems. for instance, phenolic compounds have been found to inhibit both bacterial abundance and microbial metabolism, even in the presence of high oc and nutrients (fenner & freeman 2011; mann et al. 2014). while we did not measure oc composition or quality in our study, these results suggest soil oc composition must also be taken into account when estimating potential c respiration potentials from recently thawed permafrost. previous studies have shown that permafrost disturbance, including thermokarst activity, can export large amounts of labile doc to inland waters (vonk et al. 2013; abbott et al. 2014). however, in our study there were no statistically significant differences in c table 4. results from forward stepwise multiple linear regression analyses examining c respiration as the response variable in terms of soil extract c respired (mg), c respired per gram soil oc (mg c g oc−1) and the fraction total doc respired (%). soil oc contents and soil extract doc and log(po4-p) concentrations did not predict c respiration in any model. soil extract log(nh4-n) concentrations predicted c respiration in terms of soil extract c respired (mg) and the fraction total doc respired (%). carbon respiration per gram soil oc had no significant predictor variables in the final regression model. c respiration parameter soil extract c respired (mg c) c respired per g soil oc (mg c g oc−1) fraction total doc respired (%) β0 (intercept) value −0.760 1.149 0.502 se 0.545 0.085 7.811 p 0.201 0.113 0.950 β1 (log[nh4-n]) value 0.221 – b 3.225 p 0.046 –b 0.043 se 0.094 –b 1.341 regression model df 8 9 8 rmsea 0.45 0.27 6.46 r2 0.411 –c 0.420 p 0.046 –c 0.043 a root mean square error. b parameter was not in final regression model. c no parameters were significant (p ≤ 0.05) in final regression model. 8 j.k. heslop et al. respiration between previously undisturbed profiles (duvyanni yar and shuchi lake ridge) and sites where the surface had been previously disturbed (bulldozer site, tube dispenser lake, rodinka). this is consistent with findings by larouche et al. (2015), which showed that labile doc fractions in alaskan inland waters were not significantly altered by disturbance. previously undisturbed sites in our study had higher oc contents in their profiles, and higher oc contents in bulk soil samples positively correlated with higher doc levels in our soil extracts (r = 0.58, p = 0.029). although the fractions of watersoluble oc in our soil samples were low (0.15– 1.78%), the proportions of soil oc extracted in our study were consistent with general proportions of water-extractable soil organic matter in total soil organic matter (2–5%; ellerbrock et al. 1999; he et al. 2011). while higher soil oc contents correlated with higher doc concentrations in our soil extracts, higher extract doc concentrations did not lead to higher c respiration potentials and soil extract c respiration potentials did not correlate with soil oc contents in our study. our finding that higher extract doc concentrations did not necessarily yield higher c respiration potentials contradicts previous studies in which higher doc concentrations in inland waters led to increased release of co2 (algesten et al. 2005; battin et al. 2008; lapierre et al. 2013). one possible explanation is that c respiration in our study is limited by an alternative factor other than doc concentrations. for instance, macronutrient availability, organic matter composition and microbial communities within our incubations may have influenced extract c respiration rates observed in this study. prior studies have found that landscapescale variation in soil c bioavailability can be linked to soil c to n ratios, with higher values leading to more c respiration (schuur et al. 2015). in aquatic systems, nutrient concentrations and ratios in the environment could limit c respiration when they deviate from the redfield ratio (16 n: 1 p) or microbial n:p biomass ratios (7 n: 1 p; cleveland & liptzin 2007). previous studies in arctic aquatic ecosystems found bacterial production is usually limited by phosphorous (granéli et al. 2004; hobbie & laybournparry 2008), but we did not find a statistically significant positive relationship between extract c respiration potentials and po4-p concentrations in our study. our multiple linear regression analyses indicated positive correlation between c respiration and ammonium (nh4-n) concentrations in the soil extracts, suggesting potential n limitation in our system. however, since ammonium is only a fraction of the total n pool, we are unable to determine if there is significant correlation between c respiration and c to n ratios in our study. approximately 8.9–31.2% of the total doc in our incubation vials was respired during our five-day incubation period. this is consistent with several prior laboratory incubations which found that only 4–60% of doc from soils is available for microbial respiration (kalbitz et al. 2003; holmes & mcclelland 2008; vonk et al. 2013; larouche et al. 2015; spencer et al. 2015). while we acknowledge the limitations of using laboratory incubations to extrapolate what proportion of water-soluble soil oc will be respired upon entering inland waters, we note that our incubation period (five days) is consistent with mean residence times it takes water to move from permafrost thaw sites to the kolyma river main stem (three to seven days; vonk et al. 2013). in the kolyma river basin and other inland water sites, the proportion of soil oc available for microbial respiration and, by extension, the soil’s net c respiration potential, increases as initial processing and breakdown by ultraviolet light makes oc compounds more bioavailable for heterotrophic respiration and the production of co2 (cory et al. 2013). other studies suggest up to 22% of doc can be sequestered by reactive iron and thus made unavailable for c respiration (salvadó et al. 2015). therefore, further research is necessary to understand the full c respiration potential of water-soluble oc from the kolyma river yedoma region’s thawing permafrost as it is processed in situ. conclusions examining soil oc quantity and quality can lead to a better understanding of how much soil c can be immediately processed following permafrost thaw and watersoluble oc release to inland waters. our study indicates that while soil oc content is spatially variable in the kolyma river basin it is not necessarily an indicator of c respiration potentials upon permafrost thaw and export to inland waters. sites which had not experienced prior disturbance had higher soil oc contents, but there were no statistically significant differences in c respiration potentials between disturbed versus undisturbed sites in our study. this suggests that alternative oc quality parameters, including exposure to freeze–thaw cycling, the extent of seasonal interactions with water and the presence of inhibitory organic compounds, may also play a role in watersoluble c respiration potentials. it is also important to consider factors which may alter in situ c respiration from thawing permafrost, such as doc sorption to mineral soils and the additional physical procession doc experiences after being released to inland waters, when estimating the true magnitude of c release from thawing permafrost soils. polar research 9 acknowledgements this study was supported by the national science foundation as part of the polaris project (nsf-0732586 and nsf-0732944). additional support for jkh and kmwa came from nsf-1107892 and nasannx11ah20g. we would like to thank e. bulygina, a. bunn, r.m. holmes, p. mann, j. schade, n. zimov and s. zimov for assisting with data collection and/or project organization. we thank the anonymous reviewers for their detailed comments, which greatly assisted in improving the manuscript. an earlier version of this manuscript benefitted from reviews from b. abbott and c. griffin. disclosure statement no potential conflict of interest was reported by the authors. funding this work was supported by the national aeronautics and space administration (nsf-0732586; nsf-0732944; nsf1107892; nasa-nnx11ah20g). references abbott b.w., larouche j.r., jones j.b. jr., bowden w.b. & balser a.w. 2014. elevated dissolved organic carbon biodegradability from thawing and collapsing permafrost. journal of geophysical research—biogeosciences 119, 2049–2063. ågren a., berggren m., laudon h. & jansson m. 2008. terrestrial export of highly bioavailable carbon from small boreal catchments in spring floods. freshwater biology 53, 964–972. algesten g., sobek s., bergström a.k. & jonsson a. 2005. contribution of sediment respiration to summer co2 emission from low productive boreal and subarctic lakes. microbial ecology 50, 529–535. battin t.j., kaplan l.a., findlay s., hopkinson c.s., marti e., packman a.i., newbold j.d. & sabater f. 2008. biophysical controls on organic carbon fluxes in fluvial networks. nature geoscience 1, 95–100. brown j., ferrians o.j. jr, heginbottom j.a. & melnikov e. s. 1998 (revised 2001). circum-arctic map of permafrost and ground ice conditions. boulder, co: national snow and ice data center/world data center for glaciology. cleveland c. & liptzin d. 2007. c:n:p stoichiometry in soil: is there a “redfield ratio” for the microbial biomass? biogeochemistry 85, 235–252. cole j.j., prairie y.t., caraco n.f., mcdowell w.h., tranvik l.j., striegl r.g., duarte c.m., kortelainen p., downing j. a., middelburg j.j. & melack j. 2007. plumbing the global carbon cycle: integrating inland waters into the terrestrial carbon budget. ecosystems 10, 172–185. cory r.m., crump b.c. & dobkowski j.a. 2013. surface exposure to sunlight stimulates co2 release from permafrost soil carbon in the arctic. proceedings of the national academy of sciences of the united states of america 110, 3429–3434. cory r.m., ward c.p., crump b.c. & kling g.w. 2014. sunlight controls water column processing of carbon in arctic fresh waters. science 345, 925–928. davydov s.p., fyodorov-davydov d.g., neff j.c., shiklomanov n.i. & davydova a.i. 2008. changes in active-layer thickness and seasonal fluxes of dissolved organic carbon as a possible baseline for permafrost monitoring. in kane d.l. & hinkel k.m. (eds.): ninth international conference on permafrost. vol. 1. pp. 333– 337. fairbanks: institute of northern engineering, university of alaska fairbanks. drake t.w., wickland k.p., spencer r.g.m., mcknight d. m. & striegl r.g. 2015. ancient low-molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw. proceedings of the national academy of sciences 112, 13946–13951. dutta k., schuur e.a.g., neff j.c. & zimov s.a. 2006. potential carbon release from permafrost soils of northeastern siberia. global change biology 12, 2336– 2351. ellerbrock r.h., höhn a. & gerke h.h. 1999. characterization of soil organic matter from a sandy soil in relation to management practice using ftir spectroscopy. plant and soil 213, 55–61. fenner n. & freeman c. 2011. drought-induced carbon loss in peatlands. nature geoscience 4, 895–900. frauenfeld o.w., zhang t. & barry r.g. 2004. interdecadal changes in seasonal freeze and thaw depths in russia. journal of geophysical research—atmospheres 109, d05101, doi: 10.1029/2003jd004245. frey k.e. & mcclelland j.w. 2009. impacts of permafrost degradation on arctic river biogeochemistry. hydrological processes 23, 169–182. gost. 2008. grunty. metody laboratoriogo opredelenija granulometričeskogo (zernovogo) i mikroagregatnogo sostava. gost 12536-79. (soils. methods of laboratory granulometric [grain-size] and microaggregate distribution. gost [state standard] 12536-79.) moscow: ipk izdatelstvo standartov. goulden m.l., wofsy s.c. & harden j.w. 1998. sensitivity of boreal forest carbon balance to soil thaw. science 279, 214–217. granéli w., bertilsson s. & philibert a. 2004. phosphorus limitation of bacterial growth in high arctic lakes and ponds. aquatic sciences 66, 430–439. greenberg a.e., clesceri l.s., eaton a.d. & franson m.a. h. (eds.) 1992. standard methods for the examination of water and wastewater. 18th edn. washington, dc: american public health association. griffin c.g., frey k.e. & rogan j. 2011. spatial and interannual variability of dissolved organic matter in the kolyma river, east siberia, observed using satellite imagery. journal of geophysical research—biogeosciences 116, g03018, doi: 10.1029/2010jg001634. he z., honeycutt c.w. & zhang h. 2011. elemental and fourier transform-infrared spectroscopic analysis of waterand pyrophosphate-extracted soil organic matter. soil science 176, 183–189. hinkel k.m. & nelson f.e. 2003. spatial and temporal patterns of active layer thickness at circumpolar active layer monitoring (calm) sites in northern alaska, 1995–2000. journal of geophysical research— atmospheres 108, 183–189. hobbie j.e. & laybourn-parry j. 2008. heterotrophic microbial processes in polar lakes. in vincent w.f. & laybourn-parry j. (eds.): polar lakes and rivers. pp. 197– 212. oxford: oxford university press. holmes r.m. & mcclelland j.w. 2008. lability of doc transported by alaskan rivers to the arctic ocean. geophysical research letters 35, l03402, doi: 10.1029/2007gl032837. holmes r.m., mcclelland j.w., peterson b.j., tank s.e., bulygina e., eglinton t.i., gordeev v.v., gurtovaya 10 j.k. heslop et al. https://doi.org/10.1029/2003jd004245 https://doi.org/10.1029/2010jg001634 https://doi.org/10.1029/2007gl032837 t.y., raymond p.a., repeta d.j., staples r., striegl r.g., zhulidov a.v. & zimov s.a. 2012. seasonal and annual fluxes of nutrients and organic matter from large rivers to the arctic ocean and surrounding seas. estuaries and coasts 35, 369–382. hugelius g., strauss j., zubrzycki s., harden j.w., schuur e.a.g., ping c.-l., schirrmeister l., grosse g., michaelson g.j., koven c.d., o’donnell j.a., elberling b., mishra u., camill p., yu z., palmtag j. & kuhry p. 2014. estimated stocks of circumpolar permafrost carbon with quantified uncertainty ranges and identified data gaps. biogeosciences 11, 6573–6593. kalbitz k., schmerwitz j., schwesig d. & matzner e. 2003. biodegradation of soil-derived dissolved organic matter as related to its properties. geoderma 113, 273–291. kanevskiy m., shur y., fortier d., jorgenson m.t. & stephani e. 2011. cryostratigraphy of late pleistocene syngenetic permafrost (yedoma) in northern alaska, itkillik river exposure. quaternary research 75, 584– 596. knoblauch c., beer c., sosnin a., wagner d. & pfeiffer e.m. 2013. predicting long-term carbon mineralization and trace gas production from thawing permafrost of northeast siberia. global change biology 19, 1160– 1172. lapierre j.-f., guillemette f., berggren m. & del giorgio p. a. 2013. increases in terrestrially derived carbon stimulate organic carbon processing and co2 emissions in boreal aquatic ecosystems. nature communications 4, article no. 2972, doi: 10.1038/ncomms3972. larouche j.r., abbott b.w. & bowden w.b. 2015. the role of watershed characteristics, permafrost thaw, and wildfire on dissolved organic carbon biodegradability and water chemistry in arctic headwater strams. biogeosciences 12, 4221–4233. lee h., schuur e.a.g., inglett k.s., lavoie m. & chanton j. p. 2012. the rate of permafrost carbon release under aerobic and anaerobic conditions and its potential effects on climate. global change biology 18, 515–527. mann p.j., davydova a., zimov n., spencer r.g.m., davydov s., bulygina e., zimov s. & holmes r.m. 2012. controls on the composition and lability of dissolved organic matter in siberia’s kolyma river basin. journal of geophysical research —biogeosciences 117, g01028, doi: 10.1029/2011jg001798. mann p.j., sobczak w.v., larue m.m., bulygina e., davydova a., vonk j.e., schade j., davydov s., zimov n., holmes r.m. & spencer r.g.m. 2014. evidence for key enzymatic controls on metabolism of arctic river organic matter. global change biology 20, 1089–1100. matzner e. & borken w. 2008. do freeze–thaw events enhance c and n losses from soils of different ecosystems? a review. european journal of soil science 59, 274–284. mcdowell w.h. & wood t. 1984. podzolization: soil processes control dissolved organic carbon concentrations in stream water. soil science 137, 23–32. mcguire a.d., macdonald r.w., schuur e.a.g., harden j. w., kuhry p., hayes d.j., christensen t.r. & heimann m. 2010. the carbon budget of the northern cryosphere region. current opinion in environmental sustainability 2, 231–236. neff j.c. & asner g.p. 2001. dissolved organic carbon in terrestrial ecosystems: synthesis and a model. ecosystems 4, 29–48. neff j.c., finlay j.c., zimov s.a., davydov s.p., carrasco j. j., schuur e.a.g. & davydova a.i. 2006. seasonal changes in the age and structure of dissolved organic carbon in siberian rivers and streams. geophysical research letters 33, l23401, doi: 10.1029/2006gl028222. ohno t., he z., tazisong i.a. & senwo z.n. 2009. influence of tillage, cropping, and nitrogen source on the chemical characteristics of humic acid, fulvic acid, and water-soluble soil organic matter fractions of a longterm cropping system study. soil science 174, 652–660. pribyl d.w. 2010. a critical review of the conventional soc to som conversion factor. geoderma 156(3–4), 75–83. rigler f.h. 1966. radiobiological analysis of inorganic phosphorus in lakewater. verhandlungen der internationalen vereinigung für theoretische und angewandte limnologie 16, 465–470. romanovskij n.n. 1993. osnov’y kriogeneza litosfery. (fundamentals of cryogenesis of the lithosphere.) moscow: moscow state university. romanovsky v.e., smith s.l. & christiansen h.h. 2010. permafrost thermal state in the polar northern hemisphere during the international polar year 2007–2009: a synthesis. permafrost and periglacial processes 21, 106–116. salvadó j.a., tesi t., andersson a., ingri j., dudarev o. v., semiletov i.p., & gustafsson ö.. 2015. organic carbon remobilized from thawing permafrost is resequestered by reactive iron on the eurasian arctic shelf. geophysical research letters 42, 8122-8130. doi: 10.1029/2010gl042909 schirrmeister l., grosse g., wetterich s., overduin p.p., strauss j., schuur e.a.g. & hubberten h.-w. 2011. fossil organic matter characteristics in permafrost deposits of the northeast siberian arctic. journal of geophysical research—biogeosciences 116, g00m02, doi:10.1029/2011jg001647. schirrmeister l., kunitsky v., grosse g., wetterich s., meyer h., schwamborn g., babiy o., derevyagin a. & siegert c. 2011. sedimentary characteristics and origin of the late pleistocene ice complex on north-east siberian arctic coastal lowlands and islands—a review. quaternary international 241, 3–25. schuur e.a.g., bockheim j., canadell j.g., euskirchen e., field c.b., goryachkin s.v., hagemann s., kuhry p., lafleur p.m., lee h., mazhitova g., nelson f.e., rinke a., romanovsky v.e., shiklomanov n., tarnocai c., venevsky s., vogel j.g. & zimov s.a. 2008. vulnerability of permafrost carbon to climate change: implications for the global carbon cycle. bioscience 58, 701–714. schuur e.a.g., mcguire a.d., schädel c., grosse g., harden j.w., hayes d.j., hugelius g., koven c.d., kuhry p., lawrence d.m., natali s.m., olefeldt d., romanovsky v.e., schaefer k., turetsky m.r., treat c. c. & vonk j.e. 2015. climate change and the permafrost carbon feedback. nature 520, 171–179. sher a.v., kaplina t.n., giterman r.e., lozhkin a., archangelov a.a., kiselyov s.v., kouznetsov y.v., virina e.i. & zazhigin v.s. 1979. late cenozoic of the kolyma lowland: xiv pacific science congress. tour guide xi, khabarovsk, august 1979. moscow: publications of the academy of science of the ussr. solov’ev p.a. 1959. kriolitozona severnoj casti leno– amginskogo meždurecija. (permafrost zone of the northern part of the lena–amga interfluve.) moscow: publications of the academy of science of the ussr. spencer r.g.m., mann p.j., dittmar t., eglinton t.i., mcintyre c., holmes r.m., zimov n. & stubbins a. polar research 11 https://doi.org/10.1038/ncomms3972 https://doi.org/10.1029/2011jg001798 https://doi.org/10.1029/2006gl028222 https://doi.org/10.1029/2010gl042909 https://doi.org/10.1029/2011jg001647 2015. detecting the signature of permafrost thaw in arctic rivers. geophysical research letters 42, 2830–2835. stocker t.f., qin d., plattner g.-k., tignor m., allen s.k., boschung j., nauels a., xia y., bex v. & midgley p.m. (eds.) 2013. climate change 2013. the physical science basis. contribution of working group i to the fifth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. strauss j., schirrmeister l., grosse g., wetterich s., ulrich m., herzschuh u. & hubberten h.-w. 2013. the deep permafrost carbon pool of the yedoma region in siberia and alaska. geophysical research letters 40, 6165–6170. striegl r.g., aiken g.r., dornblaser m.m., raymond p.a. & wickland k.p. 2005. a decrease in discharge-normalized doc export by the yukon river during summer through autumn. geophysical research letters 32, l21413, doi: 10.1029/2005gl024413. tao s. & lin b. 2000. water soluble organic carbon and its measurement in soil and sediment. water research 34, 1751–1755. tarnocai c., canadell j.g., schuur e.a.g., kuhry p., mazhitova g. & zimov s. 2009. soil organic carbon pools in the northern circumpolar permafrost region. global biogeochemical cycles 23, gb2023, doi: 10.1029/ 2008gb003327. taylor b.w., keep c.f., hall r.o., koch b.j., & tronstad l. m. 2007. improving the fluorometric ammonium method: matrix effects, background fluorescence, and standard additions. journal of the nprth american bentholical society 26, 167-177. vonk j.e., mann p.j., davydov s., davydova a., spencer r.g. m., schade j., sobczak w.v., zimov n., zimov s., bulygina e., eglinton t.i. & holmes r.m. 2013. high biolability of ancient permafrost carbon upon thaw. geophysical research letters 40, 2689–2693, doi: 10.1002/grl.50348. vtyurin b.i. 1975. podzemnye l’dy sssr. (ground ice of the ussr.) moscow: nauka. walter anthony k.m., zimov s.a., grosse g., jones m.c., anthony p.m., chapin f.s. iii, finlay j.c., mack m.c., davydov s., frenzel p. & frolking s. 2014. a shift of thermokarst lakes from carbon sources to sinks during the holocene epoch. nature 511, 452–456. walter k.m., edwards m.e., grosse g., zimov s.a. & chapin f.s. 2007. thermokarst lakes as a source of atmospheric ch4 during the last deglaciation. science 318, 633–636. wang j., song c., hou a. & wang l. 2014. co2 emissions from soils of different depths of a permafrost peatland, northeast china: response to simulated freezing–thawing cycles. journal of plant nutrition and soil sciences 177, 524–531. wickland k.p., neff j.c. & aiken g.r. 2007. dissolved organic carbon in alaskan boreal forest: sources, chemical characteristics, and biodegradability. ecosystems 10, 1323–1340. zhang t., frauenfeld o.w. & serreze m.c. 2005. spatial and temporal variability in active layer thickness over the russian arctic drainage basin. journal of geophysical research—atmospheres 110, d16101, doi: 10.1029/ 2004jd005642. zimov s.a., davydov s.p., zimova g.m., davydova a.i., schuur e.a.g., dutta k. & chapin f.s.iii 2006. permafrost carbon: stock and decomposability of a globally significant carbon pool. geophysical research letters 33, l20502, doi: 10.1029/2006gl027484. zimov s.a., schuur e.a.g. & chapin f.s. iii, 2006. permafrost and the global carbon budget. science 312, 1612–1613. zimov s.a., semiletov i.p., daviodov s.p., voropaev y.v., prosyannikov s.f., wong c.s. & chan y.-h. 1993. wintertime co2 emission from soils of northeastern siberia. arctic 46, 197–204. zimov s.a., voropaev y.v., semiletov i.p. & davidov s.p. 1997. north siberian lakes: a methane source fueled by pleistocene carbon. science 277, 800–802. 12 j.k. heslop et al. https://doi.org/10.1029/2005gl024413 https://doi.org/10.1029/2008gb003327 https://doi.org/10.1029/2008gb003327 https://doi.org/10.1002/grl.50348 https://doi.org/10.1029/2004jd005642 https://doi.org/10.1029/2004jd005642 https://doi.org/10.1029/2006gl027484 abstract materials and methods study site and sample collection soil characteristics soil extract chemistry respiration experiments statistics results soil characteristics river water and soil extract chemistry carbon respiration discussion conclusions acknowledgements disclosure statement funding references suspension settling effect on macrobenthos biomass distribution in the hornsund fjord, spitsbergen krzysztof gorlich, jan m. slaw ski and marek zajqczkowski gorlich. k., weslawski, j . m. & zaj+czkomki, m. 198f: suspension settling effect on macrobenthos biomass distribution in the hornsund fjord, spitsbergen. polar research 5 n.s., 175-192. seasonal variations and spatial distribution of suspension composition and concentration were determined in the hornsund fjord on south spitsbergen along with bottom sediment mineralogy and glacial-marine mud accumulation rates. these data were related to macrobenthos biomass dbtribution, as well as geochemical and h y d r o d i c data. the axial di-iw of sediment acclgnulation rates follows exponential decay. sbpes of the seaward decay are different for individual meltwater sources in hornsund and, in general, tbey are higher than in river-fed fjords. intensity of suspension settling is enhanced by strong retardation of meltwater flow and turbulence within the shear layer of meltwater jet sliding over strongly saline water. the most intensive settling, controlling the overall efficiency of mud deposition (up to 35 m / a ) occurs in the ice-proximal jet zone of meltwater plume. it results from turbulent diffusion of dense suspension (>1,ooo mg/l) t o the underlying d w a t e r layer. within the more distal, dow-advection zone the sediment accumulation rate fails below 1 m / a . suspension is deposited here mostly due to slow settling of mature flocs across the halocline. this bipartite lateral zonation results in (1) clay-mineral segregation observed in bottom mud in the ice-proximal jet zone (2m, large-flake muscovite is separated from 1md clay-grade iliite), and (2) high accumulation rate and extremely rapid decay away from the source. high concentration of surface-active clays in the rapidly accumulating sediment renders the proximal mud a closed system and a physical trap for nutrients. the seasonal rhythm of changes in suspension composition reveals a time lag between maximum of organic suspension concentration and onset of dastic sedimentation. this lag along with the absolute dominance of clastic flux during summer-autumn, result in sulphidic (dark-light) lamination of ice-proximal mud. high clastic input and high surface water turbidity result in formation of a benthos-poor zone in the ice-proximal settings. there, formation and preservation of original monosulphidic lamination and scarcity of benthic life are mutually dependent. control over these follows by damping of primary production in the photic zone and trapping of nutrients in the bottom sediment by clastic dilution and fast burial of organic material. krzysztof gorlich, institute of geological sciences, polish academy of sciences, ul. senacka 3. 31-002 krakdw. poland; jan m . wptawski & marek zajqczkowski, lnrtitute of oceanology, polish academy of sciences, ul. powstancdw warszawy 55, 81-967 sopot. poland; march 1987 (revised july 1987). settling of suspension in the forefield of tidewater glaciers is by no means fully understood and its peculiarities not well defined. also, in the result ing glacial-marine mud the mutual relations between the extreme sediment loading, geo chemical environment in the sediment, and abun dance of benthic life need clarifying. the present paper aims at contributing data on the above problems and, specifically, we put forward the following questions: (1) peculiarities of mechanism of fine sediment settling in the forefield of tidewater glaciers: -seasonal rhythmicity of suspension settling, -mechanisms controlling lateral distribution of sediment accumulation rates in ice-proximal settings. ( 2 ) main agents causing strong lateral biomass changes and the related problem of primary con trol over formation and preservation of original sedimentary structures (e.g. varve-like lamination). the sediment deposited in the proximity of an ice cliff seems to be exceptionally fine, with silt and clay fraction constituting up to 90% of the bulk sample. the transition from mud to outwash and diamict facies (or inverse) in vertical sections and laterally, is rapid. this is observed both in the spitsbergen fjords of today (elverh0i et al. 1983; gorlich in print) and in the pleistocene sequences (e.g. mccabe et al. 1987). it suggests that in a tidewater-glacier environment intensive settling of fines from the meltwater overflow starts nearly at the ice cliff, producing fine intercalations within the coarse-grained bottom sediment and, 176 k . gorlich, j . m . wgsiawski & m . zajgczkawski fig. 1. sketch map of spitsbergen. 1. location of the study area, 2. sampling sites (grab samples) in storfjorden and their identification. already hundred metres or so from the source glacier, continuous mud sequences. we noted that suspension settling intensities differ for individual tidewater-glacier subbasins of hornsund and, even more significantly, they differ with respect to suspension behaviour observed in river-fed fjords, or, as an example of the temperate zone micro-tidal estuary at the vistula river mouth in the baltic sea. hence, we assumed that to explain near-source suspension settling patterns one must invoke, besides hori zontal salinity gradients and discharge, other con trolling mechanisms too, in particular, vertical salinity gradients, mineral and textural com position of original suspension, as well as dynamics of the discharge jet. our approach in the present study was to collect such sets of field data which could be used to test the applicability of the existing experiment-based models of suspension settling and formation of fine sediment. in order to do so, we sampled suspension and bottom mud. the present report also includes data on the distribution pattern of fig. 2. sampling stations in hornsund. inset map shows enlarged isbjornhamna. 1. shoreline, 2. ice cliffs of tidewater glaciers. 3. 100-m isohypse (on land). 4 . isobaths with depths in metres, 5 . major streams and lakes, 6. bottom sediment sampling stations (grab). 7 . samples (with their identification) discussed in this paper, 8. sediment cores recovered with kullenberg corer, 9. meltwater outflows in isbjornhamna. suspension settling effect on macrobenthos biomass distribution 177 bottom macrofauna in hornsund, and some hydrological and geochemical results. the paper focuses on two subbasins of hornsund on south spitsbergen (figs. 1 and 2), isbjornhamna and brepollen, and the discussion is concentrated on the phenomena occurring in the ice-proximal settings. previous work much effort has been devoted to study suspension flocculation and settling in natural and experi mental systems. the experiments in simplified systems (e.g. kranck 1975, 1980, 1986; gibbs 1985; green 1987) and theoretical considerations (e.g. hahn & stumm 1970) offered insight into elementary processes during flocculation and set tling, but they still failed to produce a coherent comprehensive model for natural estuaries (sen su lato). this is due to the fact that some crucial agents are disregarded in the experiments. these omitted or underestimated factors are (1) dif ferent crystallochemical quality of particles in the far ends of the size spectra (from surface-active: sheet silicates, organic matter, iron and manga nese hydroxides, to inert: quartz, feldspars, and carbonates), (2) turbulence, and (3) localized advection and convection within the water mass to name only the most significant. observations on the sediment loading controls over the bottom fauna communities in fjords are abundant in the literature (see farrow et al. 1983 with references). few papers, however, deal with very proximal settings in fjord environments dominated by active tidewater glaciers. pearson (1980) gave a comprehensive review of current understanding of the fjord macrobenthos, con cluding that the ecology of the arctic fjords domi nated by tidewater glaciers differs from that of the boreal to temperate fjords. the most charac teristic factors affecting benthic fauna distribution in the arctic tidewater-glacier dominated fjords are (1) the presence of strongly seasonal fresh water discharge, (2) high sedimentation rates, and (3) high oxygen and nutrient concentration in near bottom waters (appolonio 1973; pearson 1980; gulliksen et al. 1984). the field research on suspension settling in the most proximal settings is scarce, although numerous conceptual models for tidewater glacier sedimentation have been elaborated (domack 1983; gilbert 1983; molnia 1983; powell 1984). this study will also refer to the papers dealing sedimentologically with glacial-marine sediments of spitsbergen fjords ( e l v e r h ~ i et a]. 1980, 1983; elverhd 1984). setting hydrography hornsund fjord (fig. 2), henceforward denoted as hornsund, is situated on southern spitsbergen, opening t o the greenland sea. morphologically it is divided into several troughs separated by sills (there is no sill at the fjord’s mouth). the central trough is 200 m deep. the ice-proximal troughs are 55 m (isbjornhamna), 150 m (brepollen), and 180 m (vestre burgerbukta and samarinvigen) deep. hydrologically, hornsund is under mixed influence from atlantic coastal water and atlantic core water (swerpel 1985; weslawski et al. 1985). bottom water salinities range from 33.5 to 35per thousand, whereas surface water salinities reveal horizontal gradients resulting from mixing of meltwater with underlying saline water (op cit.). salinities of surface water rarely fall beneath 20 per thousand. water stratification is strong and sedimen tologically significant only within the proximal forefield subbasins of the debouching tidewater glaciers (urbanski et al. 1980; swerpel1985; gor lich & stepko in print). freshwater discharge is unknown and, so far, impossible to evaluate due to scarcity of pertinent hydrographic data from ice-proximal zones. the current system of hornsund as a whole is unknown. a photogrammetric record of sea-ice drift (madejski 1985) suggests that the surface water movements in the fjord are dominated by slow tidal currents (spring-tide amplitude is about 1.5 m) and drift currents strongly depending on the instantaneous wind directions. the geometry and wind-dependent fluctuation of meltwater plume dispersal in the proximities of the tide water-glacier are shown in fig. 3, using the example of isbjornhamna. sediment sources bedrock in the source areas covers a wide range of ages and lithologies (fig. 4), from metamorphic rocks of the precambrian hecla hoek complex in 178 k. gorlich, j . m. wphvskicc hi. 2!ajwkowski salinity [ "/00] i i . 1 ... .:... 2 1 ) 3 1 _ ) 4 + 5 -6 7 0 0 1 5 6 6 9 0 5 8 10 0 7 3 5 7 11 -31 12 -50 13 -17 14 -1w15 fig. 3. dynamic patterns of meltwater plume dispersal in isbjomhamna, depending on the wind direction. a & b. salinity and suspension concentration data collected im 5 july 1983, by wind direction loo" and force 3-4 m/s. c & d. analogous data collected on 14 july 1983, by wind direction 270" and force 5 m/s. 1. resuspension of bottom sediment, 2. remnant suspension left-over after the change of plume direction, 3. wind direction, 4. direction of the plume motion, 5 . location of meltwater input, 6. tidewater glacier front, 7. shoreline, 8 . recorded course of the visible boundary of the sediment-laden water, 9. measured salinity values (a & c). 10. measured suspension concentrations (b & d), 11. suspension concentration measured on 3 july 1983, 12. isohaline 31 per thousand, 13. isoline of suspension concentration 50mg/l, 14. isohalines (a & c). 15. isolines of suspension concentration (b & d). the outer (northwestern) part, through the lower palaeozoic carbonate rocks in the central part of the fjord, to the predominantly siliciclastic upper palaeozoic and mesozoic rocks in the bay head area (for more detailed description see gorlich (1986). and references in caption to fig. 4). sediment input follows through meltwater dis charge from eight major tidewater glaciers. other sediment and freshwater sources seem negligible. the meltwater input is strongly seasonal. with freshwater discharge unknown, we cannot attempt at determining the sediment budget within the fjord. bottorn sedimenr the variety of substrata on land is reflected by conspicuous differences in lithologies of bottom sediment. five mineralogical provinces were distinguished in the bottom sediments using the relative abundance of carbonates, quartz, and feldspars (gorlich 1986). in the siliciclastic prov ince of brepollen and storfjorden there are on an average 40% quartz, 12 to 22% feldspars, and 3% carbonates. in calcareous provinces (e.g. samarinvigen) the carbonates reach 20%, the feldspars dropping to 4%. clay-mineral com position suggests existence of two distinct mineral provinces: the biotite-muscovite dominated sedi ment (up to 35% of these minerals against 10% of illite) and the illite dominated sediment (up to 25% of illite against 10% of muscovite and biotite). see fig. 4 and gorlich (1986). suspension settling effect on macrobenthos biomass distribution 179 r l b d e 1 fig. 4. schematized dominant lithologies of the exposed bedrock on land as well as clay-mineral provinces within the bottom sediment of hornsund. land lithological data compiled from birkenmajer (1960, 1964, 1975, 1977, 1978a. b), radwanski & birkenmajer (1977), siedlecka (1968), and smulikowski (1965). 1. amphibolites and mica-garnet schists, 2. phyllites, 3. marbles, limestones and dolomites, 4. siliciclastic rocks. bottom sediment provinces: 5. mus covite-biotite province, 6. illite province; in circles are sediment accumulation rates of mud types from gorlich (1986). jet zone--------h-slow-advection zonet u r b u l e n c e c o e r c e d --i d e c r e a s i n g i n t e n s i t y f l o c r u l a t i o n o f s e a w a r d ' f l o c c u l a t i o n d u e t o d i f f e r e n c e s i n n e g l i g i b l e s h e a r i n g s t i l l l a y e r s i n g i e g r a i n i n t e n s i v e s h e a r i n g s e t t l i n g v e l o c i t i e s fig. 5. model of development and sequeace of sedimentary facies in front of an oscillatory retreating (micro-surging) grounded tidewater glacier (based on the case study of the hansbreen basin in isbjornhamna, hornsund). the plot in the upper part of the figure shows inferred change of silt and clay accumulation rate with distance from the source glacier. hydrodynamic features and flocculation modes of fine suspension are according to gorlich (in print). 1. substratum rocks, 2. till, outwash and surge deposits, 3. laminated mud facies, 4. homogeneous t o bioturbated mud facies, 5. sediment-laden meltwater, 6. zone of intensive shearing on the boundary between advecting sutiicial freshet and underlying saline water (identified with halocline). 7. approximate intensity of suspended load settling, 8. discharge of meltwater from englacial channel. 180 k . goriich, j . m . wgstawski & m. zajpczkowski fig. 6. block sketch of bottom relief of isbjomhamna with features of sediment fill (based on 28 echo-sounding profiles made in 1979 by swerpel pers. comm.). 1. schematic slope lines, 2. fine sand to gravel, 3. ponded deposits of laminated mud facies, 4. ponded deposits of fine sand, 5 . outflows of glacial meltwater from englacial and subglacial channels, 6. shoreline, 7. sea level. 1 2 ---a 3 s a l i n i t y [%.i 20 25 30 . 3 5 0 e . jz i 0 d i s t a n c e f r o m i c e f r o n t fig. 7. sediment accumulation rates for selected subbasins of homsund and vertical salinity profiles in the uppermost water layer for these subbasins (inserted). hydrographic stations and water-sampling dates are indicated. the sediment-accumulation curves are based on the data from the following cores (see fig. 2): 17. 18. 19. 20. 13 (brepollen), 14. 15. 16 (burgerbukta), and 23,22.21 (isbjornhamna), as well a s o n the seismo-acoustic (boomer) data from the central fjord (the latter provided by zalewski & kowalewski pers. comm.). july salinity profile for h3 from urbanski et al. (1980). for location of hydrographic stations see fig. 9. lines indicate: 1 . plots for isbjornhamna, 2. plots for brepollen. 3. plots for burgerbukta. based on the presence of lamination or schematic presentation). the respective mud bioturbation, two main mud facies were facies are deposited at widely different rates distinguished in the bottom sediments of ranging from 35 cm/a (for the proximal laminated hornsund (gorlich 1986): laminated mud and mud) to less than 0.1 cm/a (for the distal homo homogeneous-bioturbated mud (see fig. 5 for geneous-bioturbated mud). see figs. 5 and 7. suspension settling effect on macrobenthos biomass distribution 181 besides the most proximal settings where ice rafted detritus (ird) is abundant, the ponded laminated mud facies which fills proximal basins (figs. 5 and 6), is poor in drop stones and origin ates primarily from suspension settling. coarse sand intercalations in this latter facies are rare, which excludes significant contribution from underflow sedimentation or large scale turbidity currents. small scale turbidites produced by low density currents occur in the central parts of the proximal troughs. the ird contribution increases with diminishing sediment accumulation rate, producing inverse lateral grading of sedi ment texture within the discussed mud facies. materials and methods sampling the samples for this study have been collected in hornsund and selected locations on the south spitsbergen shelf. location of sampling sites and hydrographic stations are shown in figs. 1 , 2 , and 9. water samples for salinity and suspension-con centration determinations were collected with 1-1 nansen bottles (for vertical hydrographic pro files) and with glass 1-1 bottles (for surface water samples). a total of 85 water samples was col lected between september 1982 and july 1983, and 272 water samples between september 1984 and august 1985. water sampling has been car ried out during the expeditions to the hornsund station of the institute of geophysics, polish academy of sciences. additional hydrographic data from urbanski et al. (1980) are included. the sediment samples were recovered with the petersen 0.16-m2 grab, 1-m gravity corer and dredge (on hard bottom). the preliminary results of coring with kullenberg piston corer, done by the ‘jantar’ expedition of the institute of geo physics, polish academy of sciences, in 1985, are also included (cores up to 3.5 m long). methods the results from hornsund, presented in this paper, include (1) hydrographic data, (2) sus pension concentration in vertical profiles, (3) sur face water suspension concentration in time series, (4) quantitative data on organic and inor ganic components of suspension, (5) concen tration of phytoplankton chlorophyll and zooplankton in suspension, (6) mineral com position of bottom sediment, (7) e h , ph and phosphorus concentration in bottom sediment cores, (8) sediment accumulation rates, and (9) lateral distribution of benthic biomass. water-temperature data were obtained in situ with reversible and electronic thermometers. the salinity of the water samples was determined with salinometer . weight suspension concentration was obtained by filtering of water samples through milipore 0.45 pm filters. the filters had been dried to constant weight prior t o filtration. after filtration they were dried again at 110°c for 24 hrs. and weighed. organic matter in suspension was measured as weight loss by oxidizing the filters with suspension using hydrogen peroxide. the chlorophyll concentration was measured using a spectrophotometric routine of koblentz mishke & semenova (1977). prior to mineralogical and chemical analyses, the bottom sediment samples were grain-size frac tionated by wet sieving the fraction >63 ym and centrifuging the fractions 0.2-2 pm and <0.2 ym. the separation of clay fractions was preceded by chemical purifying with acetate buffer and sodium dithionite (jackson 1974). the mineralogical methods included (1) xrd mineralogical analyses carried out on oriented (for phase determination) and random (for poly types determination and quantitative assessment) mounts, (2) determination of organic matter plus monosulphide content in the bottom sediment by heating the samples in the muffle furnace at 550°c for 24 hrs. x-ray powder diffraction of random mounts was used for quantitative determination of min eral composition of the bulk sediment samples using a method elaborated by srodod (1984) and described by gorlich (1986). the method enables distinguishing between the dioctahedral mica 1md and 2m1 polytypes. the preliminary study of cored sediments included macroscopic description and chemical analyses of cores 13 and 21 (fig. 2). eh and ph have been measured in the laboratory by inserting an electrode into the freshly cut sedi ment, immediately after the opening of a core. the unpublished ph and eh data have been offered by s.m. zalewski (pers. comm.). the phosphorus content in sediment samples was determined colorimetrically using the molybdate 182 k . gorlich, j . m . wgsiawski & m . zajpczkowski 0 10 20 d i s t a n c e f r o m t h e n e a r e s t s o u r c e q l a c i e r i l k m 4 h 5 s u s p e n s i o n c o n c e n t r a t i o n [rn g l l i $,,30 40 50 6.0," 7,o 0 o' 10 20 '? 28 ,ly 30 p-- 24 06 85 40 50 h5 s a l i n i t y [ o / i i i t krn t i 6 10( 131 k m -11 b fig. 8. vertical distribution of suspension concentration at stations in isbjornhamna (h5). isbjornhamna sill (h6), and central trough of hornsund ( h l ) . in the lower left corner are salinity profiles for station h5 in isbjornhamna for different dates. positions of the stations are shown in fig. 9. symbols denote: 1. plots for the samples collected in j u n e , 2. plots for the samples collected in september (suspension). 3. plots for the samples collected in september (salinity), 4. salinity plot for the samples collected under sea ice, 5 . bar marking salinity range for samples collected under sea ice. method. the other chemical determinations are not discussed in this paper. a petersen 0.16-rnz grab was used to obtain quantitative data on benthos. usually three samples were taken from each station. t h e sedi ment was sieved with 2 m m mesh size and the macrofauna was hand-sorted and preserved in 4 % formalin water solution. samples were taken in august 1984 and july 1985. t h e unpublished results (microseismic activity of hansbreen done by j . dqbrowski, air tern peratures. ground temperatures. and snow-cover thickness done by p. adamski and j . ksigiek) have been kindly provided by t h e authors and are used here in the discussion. results suspension dispersal sediment accumulation rates obtained in a pre vious study (gorlich 1986) for three subbasins of hornsund (isbjornhamna, burgerbukta, and brepollen-fig. 7). suggest significant differences in sediment accumulation rates. these differences suspension settling effect on macrobenthos biomass distribution 183 1 . 16”e fig. 9. mean monthly (july) suspension distribution in surface waters of hornsund. symbols: 1. above 50 mg/l, 2. 20 to 50 mg/l, 3. below 20 mg/l, 4. suspension sampling stations (irregular sampling), 5 . fixed sampling stations (suspension sampled five times in july 1985). 6. hydro graphic profiles with identification, illustrated in figs. 7 and 8. were related in the above-cited paper either to different vertical salinity gradients (inset in fig. 7) or to the position and intensity of meltwater sources. in order t o approximate the relative sig nificance of these agents and to identify new poss ible controlling factors, the time and space variability of suspension concentration and com position within the water mass were studied. the results of the investigation are shown in figs. 3, 8, 9, and 10. the development of sediment-laden freshet in the water column of the proximal bay in june may be observed at station h5 in isbjornhamna (fig. 8). the effect of the discharge plume is hardly noticeable already some 2.5 km away from the source (profile h6 in fig. 8). both the june profiles of suspension concentration at station h5 show maxima at 5 to 1om water depth. the maxima may indicate that the load of suspension settles within the advecting surface water layer. at the salinity profile for this date (station h5, lower-left corner of fig. 8) there is a secondary salinity minimum at that level, suggesting that the vertical stability of the water column is here indeed maintained by an increased suspended load. the september profiles (stations h5 and h1) show distribution of suspension during the decline of meltwater discharge. both from these profiles and from the surface water patterns in fig. 3 we may note that the suspension concentrated up to 90mg/l reveals a certain stability. the hatched fields in fig. 3 suggest that suspension remained there after a change of the main direction of plume dispersal. the september profile h5 in fig. 8 shows no indication of strong settling either. we infer that within the slowly advecting water in distal settings (or, during the decline of discharge, also in more proximal positions) the fall-out of suspension is not extremely rapid. the slowly settling ‘remnant’ suspension is deposited within the fjord during the summer months, decreasing its concentration to the level of ‘residual’ values in the range between 10 and 15mg/l. at the central fjord station h1, sus pension concentration only slightly increases dur ing summer above the ‘residual’ value. there are strong indications that a bulk of suspended load is deposited within the first few kilometres from the input where the surface water suspension concentration locally exceeds 1,000 mg/l. the averaged lateral pattern of suspension dispersal is presented in fig. 9. the map is based on the interpolated mean july values of sus pension concentration measured five times at the fixed stations and irregularly at the other indicated stations. it may be seen from this figure that the reaches of individual sources suspension depend on the geometry of the basin and the position of 184 k. gorlich, j . m. wgslawski & m. zajpczkowski .oot rg a.001 0.c 8 .p r months -100 v l l l i x x x i x i 1 i i i ill i v v v i v i i m 4 !-10. c v l l l i x x x i x i 1 i ii i l l i v v v i v i i s g 5 e, 0.5. %.f -.c o m z o + -6% c . o w c i 1°01 50 j . . , . v l l l i x x x i x i 1 i i t ill i v v v1 v i i months fig. 10. mean monthly values of total suspension concentration and its components as well as the controlling factors. a . meteorological data measured at the hornsund sation in 1985 (adamski & ksiqiek. pen. comm.): 1. snow-cover thickness, 2. mean monthly ground tem perature at 5 cm. 3. mean monthly air temperature; b. monthly counts of microquakes recorded at the hornsund station in 1985 (dgbrowski. pen. comm.) related to the calving activity of the nearby hansbreen glacier (lo-flag marks the onset of the thawing process and thus the beginning of calving and meltwater input to isbjornhamna); c. chlorophyll weight concentration (ph-flag marks the onset of primary production): d . zooplankton weight concentration (zo flag marks the first spring zooplankton bloom): e. total suspension weight concentration; data from the fixed stations in fig. 9 (vertical bars indicate standard deviation): 1. datum for september 1983. 2 . inferred course. of distribution; f. percentage of inorganic part of sus pension the appropriate flags are those from plots b, c, and d. the sources within it (e.g. brepollen, encircled by tidewater glaciers, is filled up with dense suspen sion). the lateral extent of suspension coming from individual glaciers also depends on the dis charge of meltwater sources. thus, in order to describe the elementary mechanisms of settling, we shall later discuss the lateral variability of sediment accumulation rate rather than its absol ute values (cf. fig. 7). one should note that a part of the residual suspension settling effect on macrobenthos biomass distribution 185 p o w e r l a w dependence for b o t t o m s e d i m e n t samples f r o m the v i s t u l a r i v e r m o u t h ’ 072 20 30 40 50 100% t o t a l c l a y m i n e r a l c o n t e n t fig. 11. plot of percentage ratio (mr) of 2m, muscovite to 1md illite against the total clay mineral content in surface sediment samples from the vistula river mouth (in the baltic sea) and south spitsbergen subbasins. the hornsund samples are plotted against the power-law dependence of bottom sediments from the forefield of the vistula river mouth (straight solid line, cf. belzunce et al. in print). data for samples from: 1. the vistula river mouth, 2. isbjornhamna, 3. muscovite-biotite province in hornsund and skoddebukta (see figs. 2 and 3), 4. illite province in hornsund, 5. illite province in storfjorden (see fig. 2). a delineates samples within muscovite-biotite province, b delineates samples within illite province of the south spitsbergen bottom mud. suspension in the fjord (fig. loc, d , f ) is made of organic components. the changes of phyto plankton and zooplankton concentrations pre sented in fig. 1oc and d , reveal strong maxima distinctly preceding the onset of clastic input with meltwater. the latter may be well dated using continuous microseismic data recorded at the pol ish station in hornsund (dgbrowski unpublished data). the record allows one to count quakes resulting from calving of the neighbouring hansbreen glacier (fig. lob). the calving activity is correlated with the melting of englacial waters and the beginning of meltwater discharge to isbjornhamna. comparison of the calving fre quency curve with the meteorological data (fig. 10a, b) shows that the meltwater discharge rather than the surface runoff is responsible for the bulk of clastic material delivered to the fjord. this is seen from the intensity of supply of clastic suspension to the fjord, which continues until december in spite of the presence of snow cover and mean air temperatures below freezing point since october-november. bottom sediment features the observed intensity of suspension settling is supposed to be controlled, i.a. by textural com position of suspended material. this was noted by gorlich (1986) when comparing ratios of fraction <0.2 pm to fraction 0.2-2 pm in bottom sediment samples from different basins of hornsund. a correlation between this ratio and local intensity of fine sediment settling was found; the latter feature measured as the sediment accumulation rate decay along the profile seawards from the glacier. for instance, in isbjornhamna the above fine fraction ratio (fraction c 0 . 2 pm to fraction 0.2-2pm) is on an average 0.03, and the sus pension settling is exceptionally effective, whereas for the brepollen province, the average ratio is 0.74 and the falling out by the suspension is less effective. these values of clay-fraction ratio indicate that the isbjomhamna sediment is coarser within the clay fraction than the brepollen one. unfortunately, we have no coulter-counter 186 k. gorlich, j . m. wgslawski & m. zajpczkowski fig. 12. macrobenthos biomass distribution in the surface sediments of hornsund, measured in august 1984 and july 1985. numbers in circles indicate profiles illustrated as bar diagrams in fig. 1 3 . i . >100g/m2, 2. 10-100g/m2, 3. 1-10g/m2, 4. <1 g/m2. grain-size spectra for suspension to show directly the dependence between the texture of primary suspension, its settling efficiency, and the resulting texture of the bottom sediment. however, we may use an indirect evidence. in order to do that we shall refer to the mineralogical method elaborated for the vistula river sedi ments (cf. belzunce et al. in print). this method traces gravitational segregation within fine sus pension by measuring in the bottom sediment the relative changes of abundance of two mica polytypes: 2m, muscovite and 1md illite. both polytypes, besides crystallochemical differences, reveal different specific modal grain-sizes. musco vite is a large-flake mica concentrating in the upper limits of clay fraction, whereas illite is a clay-grade mica variety. the abundance of these mica polytypes may be measured in bottom sedi ment samples using x r d patterns of random powder mounts. the method of quantitative analysis applied here is that of srodon (1984). thus, obtained data are plotted as abundance ratio muscovite/illite against the total clay-min era1 content in the samples (fig. l l ) , the total clay-mineral content being selected as a para meter well representing the sedimentary matur ity of bottom mud (or the effective length of the transportation path from the source to the site of deposition). from the figure, we can see that the data for the sediments belong~ng to the vistula river sedimentary province are plotted on the power-law curve. we may conclude that sus pension from the vistula source undergoes such differentiation during transportation that coarse grained muscovite is separated from the clay grade illite. the data for hornsund and storfjorden plotted on this graph show that (1) there are two lithologic types of fine bottom sediment in the area: the isbjornhamna and brepollen-storfjorden ones, (2) the isbjornhamna mud, although rich in clay minerals (about 50%). contains much more coarse muscovite flakes and reveals extremely rapid differentiation, (3) the brepollen-storfjor den mud types are compositionally very close to each other (in spite of their being separated by the spitsbergen mainland), contain predomi nantly illite, and segregation of muscovite from illite is only slightly more intensive here than in the vistula river sediment. benthos distribution as regards benthic macrofauna, our data from hornsund (figs. 12 and 13) show tendencies simi lar to those observed in other fjords (e.g. gage 1972; feder & matheke 1980). the taxonomic composition of benthos in the samples collected for this study will be published elsewhere (w~slawski et al. unpublished). in gen suspension settling effect on macrobenthos biomass distribution 187 b e n t h o s b i o m a s s u l e r f j o r d t r o l bastn f j o r d 1 0 3 0 71-60 51-100 1 0 0 2 0 0 ! m i d e p l h i n t e r v u l s fig. 13. dependence of macrobenthos biomass on water depth and position within the fjord. eral, 30 species of polychaeta, 22 species of mol lusca, and 28 species of crustacea have beec determined. polychaeta constitute some 80% of the benthic biomass. crustaceans are abundant only above the 30 m isobath. in the outer fjord, in its deepest part, up to 90% of the biomass with 98% frequency is composed of foraminifera of the genera rhabdammina and hyperammina. the bottom sediment of the inner fjord is prac tically devoid of microfauna. the sketch map in fig. 12 shows macrobenthos biomass distribution measured at different locations in hornsund. there is some rough simi larity between these results and the picture of suspension dispersal in fig. 9. comparison of figs. 4 and 12 suggests, in its turn, that there is no relation whatsoever between the bottom sediment lithology and abundance (mass) of benthic life. the forefields of the glaciers (inner fjord) always reveal low values of biomass, not depend ing on the depth. the sites with biomass lower than 1 g/m2 in brepollen and samarinvigen occur at depths of about 150 m, whereas at the entrance to burgerbukta the biomass approaches 100 g/m2 at a depth of 50 m. these relations are more easily visible in the synthetic graph of fig. 13. one may see that the depth-related change is less pronounced than the change related to the position within the fjord. for fine sediments occurring below the wave base and the reach of frequent iceberg plowing (i.e. beneath the depth interval 10-30 m), there is a continuous seaward increase in benthos biomass for all the depth intervals. for the central and outer fjord locations the benthic biomass also increases with depth. however, this dependence is monotonic only for the inner fjord area. discussion effects of source suspension composition on bottom sediment the clay-mineralogical procedure of analysing the muscovite/illite ratio, introduced in the preceding section, deals with bottom sediment. however, if we adopt a modified ‘perforated conveyor belt’ model of suspension settling in a fjord (cf. farrow et al. 1983; gorlich in print), the data for the sediment will become applicable to source sus pension. hence, we may characterize source sus pensions in the two subbasins of extreme conditions in hornsund, viz. isbjornhamna and brepollen: (1) isbjornhamna suspension is abun dant in coarse clays, and its segregation is very intensive, ( 2 ) brepollen-storfjorden source sus pensions are compositionally similar to each other, much more illitic and finer than the isbjornhamna one, and segregated at a rate only slightly higher than that encountered in the vistula river mouth. suspensions from different sources settle rapidly in the proximal subbasins. the rapidity is different for individual basins (fig. 7). it was shown in a previous study (gorlich 1986) that the fine sedi ment accumulation rate data for the hornsund basins may be fitted with an exponential curve according to the formula proposed by syvitski and collaborators (see farrow et al. 1983). the exponent m of this formula, determining the slope of the decay curve, falls for the hornsund basins in a range between 0.1 (brepollen and axial profile in the fjord) and 0.4 (isbjornhamna). this is on an average more (the slope being steeper) than for british columbia fjords which are fed by rivers originating from the glaciers on land. for these latter fjords the exponent m was estimated at 0.1 (farrow et al. 1983). the value of this exponent for the vistula river estuary is estimated by the present authors to be lower than in hornsund. the discussed slope of sedimentation rate decay is influenced by the dynamics of the discharge jet and the morphology of the basin. however, in the hornsund basins it is most probably controlled by vertical salinity gradients and by the primary tex ture of suspension. the former follows by lowering 188 k. gorlich, j . m . wgstawski & m . zajpczkowski of the local richardson number at the shear surface between the advecting and still-water layers, and thus enhancement of turbulence, in case of a large vertical salinity gradient (figs. 5 and 7 isbjornhamna). this, in turn, promotes excessive settling of suspension (gorlich in print). the concept of grain-size distribution in clay suspension playing a role in promoting floc culation and settling, is based on the above dis tinction of two types of suspension in hornsund, using the graph of muscovite/illite concentration ratio vs. total clay concentration (fig. 11) as well as comparing the ratios of the grain fractions <0.2 pm to 0.2-2 vm for the different basins of hornsund (gorlich 1986, see preceding section). the different sediment accumulation rates seem to be coupled with these different textural types of suspensions. besides stronger segregation of mica polytypes in hornsund subbasins than in the vistula river estuary, there is an additional specific feature of the studied bottom sediments (and hence, as we infer, source suspensions). namely, the range of total clay content for each selected group of samples (isbjornhamna, brepollen, storfjorden) is very narrow. if we consider that the distance between the far end samples is up to 15 km for the brepollen samples (or even 50 km for the storfjorden ones) we must conclude that we deal here with a sort of process where the general textural spectrum of the settling suspension is kept constant. the effect of inverse lateral grading of texture (cf. gorlich 1986), resultingfrom relatively increasing ird contribution, must be allowed for in this case (especially for the storfjorden samples). anyway, we may state that the constancy of clay content in mud, nearly independent of the distance to the source glacier. points to an excess ively intensive deposition of fines in the ice-proxi ma1 setting. the reasons for such behaviour of meltwater suspension in the tidewater-glacier sys tem are discussed elsewhere (gorlich in print). fig. 5 summarizes the main concept of the cited paper, that the excessive intensity of suspension settling in the ice-proximal zone is caused by turbulence-coerced flocculation and simultaneous turbulent diffusion of suspended load to the still water layer in the jet-zone of the meltwater plume. the annual contribution from organic com ponents in the surface water suspension is quanti tatively negligible. however, qualitatively it is of great importance. the time lag between the organic blooms and maximum of clastic supply, invoked by elverhh et al. (1980) to explain for mation of dark lamination in proximal mud, is well visible in fig. lob, c, d , f, and seems to be a source of ?annual sulphidic laminae. however, in the cores recovered in hornsund within the laminated mud facies, the distribution of dark and light laminae is in some core segments very irregular (although in general complying with the estimated yearly accumulation rates). some lami nae are double, separated by cm-thick bright layers. sedimentary features (erosional surfaces, textural grading) suggest occasional presence of intervening turbidites (gorlich 1986). the dark lamination is thus far from the varve-type regularity. applicability of suspension settling models according to the results of kranck (1980), floc culated suspension would attain uniform con centration in a short interval of time independently of the initial concentration. if we adopted kranck’s (op. cit.) interpretation, we snould have expected different settling mag nitudes in proximal zones, which would then be equalized in more distal settings. this seems t o be the case in hornsund. if we further assumed validity of kranck’s empirical results (op. cit.), the ice-proximal situa tion would reflect the stage where the single grain and floc settling co-occur. the power-law dependence (fig. 11) and the very presence of micas’segregation also suggest that the elementary processes of suspension aggregation are at the stage of single-grain and immature floc settling in the proximal zone. however, there are some meaningful dis crepancies between the model and reality. firstly, there is the fact that fine suspension apparently settles o u t of meltwater overflow near the glacier much more rapidly than at a distance (see figs. 3 , 5, and 8). the exponential curves of the sediment accumulation rate (fig. 7) speak unequivocally for such an interpretation. experiments (kranck 1980) predict that during induction time of floc culation, i.e. at the single-grain settling stage, the sedimentation is slower than at the later floc stage, and occurs at power-law rate. the exponen tial decay of sediment accumulation rate is in clear conflict with it. moreover, if we consider the ?exponential retardation of the meltwater jet suspension settling effect on macrobenthos biomass distribution 189 ('perforated conveyor belt'), the discrepancy with the experiment becomes still greater. the presence of remnant suspension in slowly advecting surface water, persisting at concen trations above 50 mg/l for hours or days (figs. 3 and 8) also contradicts the theory that this may be the stage of exponential (i.e. the fastest) loss of sediment from suspension. the actual rates of flocculation due to differences in single-grain settling velocities, and rates of subsequent settling through halocline, are much slower than pre dicted by the experiment. that is why we favour dynamic controls over suspension fall-out from the surface plume (turbulent diffusion to the still water layer from the meltwater jet, cf. gorlich in print). conditions for benthic life depletion of the innermost fjord basins of both biomass and number of species has been com monly reported (gage 1972; gulliksen et al. 1984). this is also clearly seen in our data. specific conditions prevail in the proximal pools bounded on tidewater glaciers. high rate of clastic sediment accumulation results in dilution of organic material in the bottom sediment. high surface water turbidity and long periods of fast ice cover within the proximal basins suppress primary production and result in low flux of organic matter to the bottom. intense freshwater discharge results in water stratification with a strong stability maximum at 5-20 m water depth, restricting vertical exchange of energy and matter. it was shown by sargent et al. (1983) that a very short pelagic food web is typical of sub-arctic fjords, hardly involving bottom sediment in energy and mass cycle. the bottom sediment is oxic in its bulk (eh between 75 and 200 mv), but locally with slightly anoxic conditions within the dark laminae (about omv), and it contains on an average less than 2 wt.% of organic matter. simultaneously, the proximal sediment is typified by a relatively high phosphorus content (about 0.07 wt.%) when related to the low organic matter content. for comparison, the sediments of the baltic sea with about 10% of organic matter contain 0.07 0.09 wt.% of p. the release of phosphorus from the sediment in pools seems limited. it is marked by generally low content of phosphate ion in water (below 1 pmole/l). this concentration is slightly increased in spring. in june 1979, urbanski et al. (1980) recorded 4pmole/l of phosphate ion in near bottom water in isbjomhamna, probably due to enhanced phosphorus recycling from the organic-rich lamina deposited during winter/ spring and not yet buried by clastic material. however, since the increased content of phos phate ion in near bottom water is accompanied by its equally high content in the surface water layer (fig. 6 in urbanski et al. 1980), one may suspect that the discussed spring maxima of phos phate concentration are bound rather with surface runoff of thaw-water bringing abundant phos phates from the nearby bird rocks (plautrrs alle colonies). if this were true, the bottom water maximum would suggest that the thaw water is included in the glacial meltwater, and that the latter forms both an overflow and an underflow in the bay. the lack of the phosphate maxima in summer suggests, in turn, that the summer/ autumn meltwaters dilute the tundra phosphates to such an extent that their presence in the water mass of the bay becomes negligible. fast disappearance of the phosphate maxima in july suggests that the water mass of isbjornhamna ( 5 5 m deep) is mixed or exchanged. such exchange in pools deeper than isbjornhamna is restricted. in brepollen (up to 150 m deep), the t/s diagrams show throughout a year stagnant water with a temperature of -1.55"c, separated by sharp thermocline at a 100111 water depth from the overlying mixed (?exchanged) water (fide urbanski et al. 1980; swerpell985). the above values of phosphate concentration may be better understood when we look at the average values for the world ocean (below the photic zone) which range between 5 and 8 pmole po$1 (horne 1969), or the values for the restric ted basins of the temperate zone, e.g. the bay of finland in the baltic sea where the phosphate ion concentration reaches 45 pmole/l in spring, showing a minimum value of 3 ymolell in june (hallfors et al. 1981). the values for antarctic bottom water are above 100 pmole/l (horne 1969). it is suggested here that the residence times of macronutrients are longer in the ice-proximal pools than in the central and outer fjord basins. the low concentrations of nutrients in water mass result from low input rather than high efficiency of biological sinks. it was empirically found by hallberg et al. 190 k . gorlich, j. m . wpiawski & m . zajpczkowski (1972) that phosphorus release requires anoxic bottom water, anoxic sediment, and high con centration of organic matter. neither of these conditions are fulfilled in the hornsund proximal subbasins. the process of phosphorus release is, however, not that of inorganic solution, but is microbially mediated (mcconnell 1979; suess 1981). the observed low level of phosphorus release allows us to infer that the conditions in the sediment (oxic to locally anoxic, ph between 7 . 5 and 6.7, low organic matter content) are apparently unfavourable for microbial activity. in their study of northern norwegian balsfjorden, sargent et al. (1983) have found that molecular composition of most of the bottom sediment organic matter points to microorganisms as the main constituents. hence. the absence of effects of microbial activity (low phosphorus release) would indirectly suggest very low overall content of digestible organic matter i n the bottom sediment. in general, the ice-proximal sediments provide poor conditions for supporting benthic life, by containing low levels of organic matter bio logically available to sediment-ingesting organ isms. the weak links in this food chain are: low level of primary production, dilution of scarce organic matter i n the bottom sediment, and (possibly) low activity of bacteria. we suggest that physical controls interrupt the food chain at the level of primary production in water and bacterial activity in surface bottom sediment. hence. they are the main agents caus ing lack of higher organisms (microand macro benthos) at the bottom of the proximal subbasins. thus, we suggest that even by the lack of direct physical effect of sediment loading on bottom fauna. the benthic life would not develop abun dantly here. considering the sediment itself, the observed low activity of benthic organisms in the ice-proxi ma1 sediment results, due to poor mixing of sedi ment by bioturbation, i n (1) higher preservation potential of locally concentrated organic matter in the laminated mud facies, and (2) much better preservation of original sedimentary structures in this facies. conclusions we suggest that primary control over biological processes and over the sedimentary facies distri bution is exerted by high surface water turbidity and extremely high fine clastic flux in the most proximal settings. hence, the bipartite zonation of meltwater overflow (jet zone and slow-advection zone fig. 5 ) is reflected in the bottom sediment by occurrence of benthos-poor laminated mud deposited at a high rate, and benthos-rich homo geneous to bioturbated mud deposited at a much lower rate. in the first instance, in proximal settings the physical agents result in scarcity of biologically useful energy and digestible organic matter in the sediment by lowering the flux of organic material to the bottom and by dilution of this scarce food supply by high inorganic accumulation. fine tex ture of the rapidly accumulating bottom sediment is an additional factor impeding the matter exchange at sediment-water interface by screen ing the buried organic-rich layers. the situation in the ice-proximal subbasins is of the negative feedback type, since the poor benthic life and, consequently, low bioturbation considerably diminish the recycled fraction of organic matter, and vice versa, the lack of food suppresses the development of benthic life. the proximal laminated mud is laterally de limited from homogeneous to bioturbated mud facies bya zone where the above negative feedback mechanism ceases and is replaced by positive syn ergic action of a low sediment loading and low clastic dilution of organics, accompanied by enhanced turnover of organic matter due t o abun dant benthic life (see table 1). the picture presented of glacial-marine sedi mentation of muds in hornsund points to dif ferences between suspension settling in the temperate to sub-arctic riverine estuaries and the tidewater-glacier environments. the vertical gradients of water salinity are unusually high in the ice-proximal settings, positively influencing the retardation of meltwater jet flow, suspension flocculation, and settling rates. the effect is the exceptionally intensive trapping of fine sediment near the ice cliff. this property of the tidewater glacier sedimentary system affects not only local phenomena in fjords but also the sediment budget of the arctic and antarctic marine basins and should be considered when interpreting present day sediment patterns and paleorecord, e.g. of the north atlantic cores, regarding controls over glacial/interglacial alternation of calcareous and siliceous (temgenous) layers. suspension settling effect on macrobenthos biomass distribution 191 table 1. environmental factors affecting benthic biomass distribution in h-d. data for 60-100 m water depth interval on soft bottom. compiled from gdrlich (i%), swerpcl(198s),zakhslri&koarskwslifwrpublisheddata), and thisstudy. *summer. factor outer fjord central basin proximal subbasins 'oxygen in bottom water *po, concentration * s o 4 concentration *no2 concentration water salinity water temperature 'suspended matter in surface water *near bottom suspended matter average sediment accumulation rate p h distribution in the bottom sediment eh distribution in the bottom sediment organic matter content sediment type sediment mass redeposition bioturbation 70% 0.98 pmol/i 15.1 pnol/l 0.15 pmol/l 34.9-35%0 -1.88 to +4"c < i 5 mg/l <15 mg/l ~ 0 . 1 cm/a ird-rich homogeneous bioturbated negligible strong 80% 15.4 pmol/l 34.7-34.9% -1.88 to +yc 15 lo 20 mg/l occasionally high due to lw&&y t\lrtridity currents c. 1 cm/a 7.2 at the surface decreasing t o 6.7 at 3 m below surface c. i30 rnv at the surface, then up t o 2lxl mv fluctuating betweea 2.5 and 4 m . % ird-poor homogeneous bioturbated lowdensity turbidity currents strong o.%=o q.22 wdfi up to 98% 0.55 pmol/l 16.9 p o l / l 0.13 ~ o l / l 34.5-34.%0 -1.88 to -0.s"c tens to above 1500mg/i occasionally high due to meltwater underflows up to 35 cm/a 7.1 at the surface increasing to 7.5 at 1 m below surface c. 190 mv a8 the surfaoc. iocaliy down t o 0 mv. less than 2 w t . % laminated mud with coarse intercalations meltwater underfiows, turbidity currents negligible acknowledgements. the cooperation in field and laboratory of dr. s. rudowski, eng. w. kowalewski and dr. s. m. zalewski i s gratefully acknowledged. thanks are due to dr. j. zachowicz. geological institute, sopot, for making chemical analyses, and to the institute of geophysics, polish academy of sciences, for offering access t o sediment cores and the per tinent eh/ph data. we are indebted to dr. paul wassmann, university of bergen, for his critical comments on the first draft of this paper and to the anonymous reviewers for their efforts t o improve the final version. the study was supported by the project cpbp 03.03 of the polish academy of sciences. references appolonio, s. 1973: glaciers and nutrients in arctic seas. science 180. 491493. belzunce, j . m., gorlich, k. & helios-rybicka, e . (in print): heavy metals in surface sediments of the baltic sea: sequen tial extraction. proceedings of the conference of baltic oceanographers, copenhagen. 1986. birkenmajer. k . 1960: geological sketch of the hornsund area. pp. 1-12 in int. geol. congr. xxi sen. norden (1960). suppl. to guide, e x c . a.16: 'aspects of the geology of svalbard'. oslo. birkenmajer, k. 1964: devonian, carboniferous and permian formations of hornsund. vestspitsbergen. studia gcologica polonica 1 1 , 47-123. birkenmajer, k . 1975: jurassic and lower cretaceous sedi mentary formations in sw torell land, spitsbergen. studia geologica polonica 44, 7-43. birkenmajer, k. 1977: triassic sedimentary formations of the hornsund area, spitsbergen. studia geologica polonica 51, birkenmajer, k. 1978a: cambrian succession i n south spits bergen. studia geologica polonica 59, 7 4 6 . birkenmajer, k . 197%: ordovician succession in south spits bergen. studia geologica polonica 59, 47-82. domack, e. w. 1983: facies of late pleistocene glacial-marine sediments on whidbey island, washington: an isostatic gla cial-marine sequence. pp. 535-570 in molnia. b . f. (ed.): glacial-marine sedimentation. plenum press, new york. elverhei. a. 1984: glacigenic and associated marine sediments in the weddell sea. fjords of spitsbergen and the barents sea: a review. marine geology 57. 53-88. elverhei, a., liestel, 0. & nagy, j . 1980: glacial erosion. sedimentation and microfauna in the inner part of kongs fjorden, spitsbergen. norsk polarinstiruff skrifier 1 7 2 , 3 3 4 0 . elverha. a . , lsnne, 0. & seland, r. 1983: glaciomarine sedimentation in a modern fjord environment. spitsbergen. polar research i n . s . , 127-149. farrow, g. e., syvitski, j . p. m. g l tunniclilfe. v. 1983: suspended sediment loading on the macrobenthos in highly turbid fjord: knight inlet, british columbia. can. j. fkheries aquafic sci. 40, 273-288. feder, h. m. & matheke, g. e . m. 1980: port valedez, alaska: environmental studies 19761979. ch. 9: subtidal benthos. occ. publ. 5 . institute of marine sci.. university of a l a s k a fairbanks. gage, j. 1972: a preliminary survey of the benthic macrofauna and sediments in the loch etive and creran, sea-lochs along the west coast of scotland. j. mar. biol. ass. uk 52. 231 276. gibbs. r. j. 1985: settling velocity. diameter and density for 1-74. 192 k. gorlich, j . m . wgstawski & m. zajpczkowski flocks of illite. kaollnite and montmorillonite. 1. sed. pemol. 1985(1)7 65-68. gilbert. r . 1983: sedimentary processes of canadian arctic fjords. sedim. geol. 36, 147-175. gorlich. k. 1986: glacimarine sedimentation of muds in hornsund fjord, spitsbergen. ann. s o c . geol. polon. 56, 433477. gorlich, k. (in print): micas and texture of the recent muds in spitsbergen fjords: study of suspension settling. ann. soc. geol. polon. 58(1-2). gorlich, k. & stepko, w. (in print): hydrological phenomena related t o sea ice formation and presence observed in hornsund fjord, spitsbergen. in opalifiski, k. w. & kle kowski, r. 2. (eds.): spitsbergen '84: lnndtcape, live world and man in the high arctic. ossolineum, wrodaw. green, t. 1987: the importance of double diffusion to the settling of suspended material, sedimentology 34, 31% 331. gulliksen, b.. holte. b. & jakola, k. j . 1984: the soft bottom fauna in van mijenfjord and raudfjord, svalbard. embs 1983 materials. oslo. hahn. h . h . & stumm. w. 1971): the role of coagulation in natural waters. a m j . sci. 268, 354-368. hallberg. r o . , bagander. l . e., engvall. a , g . & schippel. f. a . 1972: method for studying geochemistry of sediment water interface. ambio 2. 71-72. hallfors, g.. niemi. a.. ackerfors. h , lassig. j . & leppako ski, e . 1981: biological oceanography. pp. 219274 in voipio. a . ( e d . ) : the baltic sea. elsevier. amsterdam. horne. r. a . 1969: marine chemistry. wiley interscience, new y o r k . 398 pp. jackson, m. l. 1974: soil chemical analysk adoanced course. published hy the author. madison, wisconsin. 895 pp. koblentz-mishke, 0. i . & semenova, m. a . 1977: phyto plankton pigments i n the mesotrophic and eutrophic regions of the tropical pacific ocean. pol. arch. hydrobiol. 24 suppl., 173-184. kranck, k . 1975: scdiment deposition from flocculated sus pension. sedimenrology 22. 111-123 kranck. k. 1980: experimentson thc significanceof flocculation in the settling of fine-gralncd sediment in still water. can. j . earrh sci. 17. 1517-1526. kranck. k . 1986: settling behavior of cohesive sediment. pp 151-169 i n metha, a . j . ( e d . ) : esruarine cohesive sedrmew dynamics. springer madejski, p . 1985: fotogrametryczny pomiar prqdd6w p o w ierzchniowych fiordu hornsund (photogrammetric measure ment of surface currents in the hornsund fjord). x i 1 s y m p o z j m polarne, szczecin 1985, materiaty, 29-30 (in polish). mccabe, a . m., dardis, g. f. & hanvey, p. a. 1987: sedi mentation at a late pleistocene ice-lobe terminating in shallow marine environments, dundalk bay, eastern ireland. sedi mentology 34, 412-494. meconneu, d . 1979: biogeochemistry of phosphate minerals. pp. 163-204 in trudinger, p. a . & swaine, d. j . (eds.): biogeochemical cycling of mineral-forming elements. elsevier, amsterdam. molnia, b. f. 1983: subarctic glacial-marine sedimentation: a model. pp. 95-144 in molnia, b. f. (ed.): glacial-marine sedimentation. plenum press, new york. pearson, t . h . 1980: macrobenthos of fjords. fjords oceano graphy, nato publ. series. powell, r . d. 1984: glacimarine processes and inductive litho facies modelling of ice shelf and tidewater sediments based on quarternary examples. marine geology 5 7 , 1-52. radwanski. a . & birkenmajer. k. 1977: oolitic/pisolitic dolo stones from the late precambrian of south spitsbergen: their sedimentary environment and diagenesis. acra geologica polonica 27, 1-39. sargent. i . r.. hopkins. c. c. e . , seiring, j . v . & youngson, a . 1983: partial characterization of organic material in surface sediments from balsfjorden, northern norway. in relation to its origin and nutritional value for sediment-ingesting animals. marine biology 76, 87-94. siedlecka, a. 1968: lithology and sedimentary environment of the hyrnefjellet beds and the treskelodden beds (late palaeozoic) at treskellen, hornsund, vestspitsbergen. studia geologica polonica 21, 53-95. smulikowski, w. 1965: petrology and some structural data of lower metamorphic formations of the hecla hoek succession in hornsund, vestspitsbergen. studia geologica polonica 18, 7-107. srodon, j. 1984: illite/smectite in low-temperature diagenesis: data from the miocene of the carpathian foredeep. clay minerals 19, 205-216. suess, e. 1981: phosphate regeneration from sediments of the peru continental margin by dissolution of fish debris. geochim. cosmochim. acra 45, 577-588. swerpel, s . 1985: the hornsund fjord: water masses. pol. polar. res. 6 , 47-96. urbanski, j . , neugebauer, e . , spacjer. r. & falkowska, l. 1980: physico-chemical characteristic of the waters of hornsund fjord on south-west spitsbergen (svalbard archi pelago) in the summer season 1979. pol. polar res. i , 43 52. no job name antarctic ascidians: an isolated and homogeneous faunapor_110 403..414 carmen primo & elsa vázquez departamento de ecoloxía e bioloxía animal, facultade de ciencias do mar, universidade de vigo, es-36310 vigo, spain abstract several biogeographical studies have already been performed on the ascidians of the antarctic region. however, new data obtained in the last few years have led us to a revision of the biogeography of this fauna. to examine the biogeographical structure of the antarctic region, we divided it into 10 sectors, depending on the principal geographical features, and then applied cluster analysis and a multi-dimensional scaling ordination to a presence/absence matrix of species for each biogeographical area. our study shows that antarctic ascidians are a very homogeneous fauna, with a high level of endemism in the whole region (25–51% of antarctic endemic species per sector), but with a low percentage of sector endemism (only up to 10%). this probably results from isolation arising from the antarctic convergence, and the vast geographical distances from adjacent regions, as well as from the relative constancy of the hydrographical conditions and the dispersal of organisms through circumpolar currents. in fact, cosmopolitan species represented only 0–7% of the total ascidian fauna in all sectors. only the bellingshausen sea (low sample size), bouvetøya (young and isolated, with an impoverished ascidian fauna) and the south sandwich islands (also young and isolated) are relatively separated. the insular sectors were more closely related to the south america and subantarctic regions than the continental ones, showing a latitudinal gradient. keywords ascidiacea; antarctica; biogeographical categories; cluster analysis; southern ocean; zoogeography. correspondence carmen primo, departamento de ecoloxía e bioloxía animal, facultade de ciencias do mar, universidade de vigo, es-36310 vigo, spain. e-mail: carprimo@uvigo.es doi:10.1111/j.1751-8369.2009.00110.x the geological history and physical and hydrographical characteristics of the antarctic region are well known (see arntz et al. 1994; longhurst 1998; clarke et al. 2005; barnes et al. 2006; knox 2007). in brief, the major geological events that have shaped the ecology and isolation of antarctica occurred following the break-up of gondwana. a deep seaway first opened between the south tasman rise and east antarctica about 32 mya, and the drake passage was probably open to deep water flow by 29 mya (lawver & gahagan 2003). these events eventually led to the formation of the west wind drift (now commonly termed the antarctic circumpolar current) and the antarctic polar front, or antarctic convergence (barnes et al. 2006). the antarctic convergence, which delimits the antarctic region (fig. 1), is a circumpolar area where cold superficial water sinks, resulting in an abrupt temperature change (barnes et al. 2006). another important feature in this region is the antarctic divergence, which separates the west wind drift and east wind drift currents (fig. 1). the great depths of the atlantic, indic and pacific basins, and the great distances from adjacent regions, isolate the entire region. ascidians have a sessile adult lifestyle and direct development or short-term planktonic larvae (with combined unhatched embryonic and larval periods of up to 16 days in cold regions; cloney et al. 2002; strathmann et al. 2006). as a result, they frequently have a restricted geographical distribution characterized by particular ecological conditions, which makes them an excellent group for biogeographical studies. although there are several papers on ascidian taxonomy in the antarctic region (sluiter 1906; millar 1960; kott 1969; monniot & monniot 1983; tatián et al. 1998a, b; sanamyan & sanamyan 2002; tatián et al. 2005; arntz et al. 2006; among others), and several biogeographical studies with antarctic, sub-antarctic and south american ascidians (ramos-esplá et al. 2005; primo & vázquez 2007a), so far no synthetic biogeographical study considering the relationship among sectors in the antarctic region, to show how isolated and homogeneous the antarctic ascidian fauna is, has been carried out. different zones have been explored in a very uneven way (monniot & monniot 1983). for example, areas such as south georgia, the south shetland islands, the western polar research 28 2009 403–414 © 2009 the authors 403 mailto:carprimo@uvigo.es antarctic peninsula, the ross sea and the eastern weddell sea have been well sampled. in contrast, the coverage of east antarctica is far from complete, and we know almost nothing of the benthic fauna of the largely inaccessible amundsen sea (clarke et al. 2004). the bellingshausen sea has been the object of several recent spanish oceanographic cruises (bentart 2003 and bentart 2006), and the first studies are now starting to appear (molluscs, troncoso et al. [2007]; soft-bottom community, saiz et al. [2008]; a new ascidian species, varela & ramos-esplá [2008]). the different sampling efforts make comparisons among different antarctic sectors difficult; even so, the identification of antarctic ascidian species is increasing (primo 2006; varela 2007; primo & vázquez 2007b). materials and methods a presence/absence matrix of 107 species and 32 biogeographical areas was constructed (table 1). the reported species included most of the known antarctic ascidians (with inherent limitations resulting from the inaccessibility of certain papers) collected from the intertidal zone to a depth of 1000 m, where the tunicate fauna shows a marked change in species composition (monniot & monniot 1982). species of uncertain identification were excluded. principally we followed the work of monniot & monniot (1983), which was updated with recent data (monniot & monniot 1994; tatián et al. 1998a; sanamyan & sanamyan 2002; ramos-esplá et al. 2005; tatián et al. 2005; arntz et al. 2006; primo & vázquez 2007b; varela & ramos-esplá 2008). as for the biogeographical areas, the antarctic continent was divided into sectors according to the main antarctic seas, capes, bays and islands, also taking into consideration the isolation or proximity of the areas (fig. 1; see sector limits below). most of the principal islands were taken as independent entities, except for some coastal islands that were included in the continental sectors. the 10 sectors were defined as follows. • the antarctic peninsula sector (pant), which includes the west coast, from its northern tip to smiley cape, and the south shetlands islands. the south shetland fig. 1 outlines of the antarctic. the sectors considered in this work are marked in boldface. antarctic ascidians c. primo & e. vázquez polar research 28 2009 403–414 © 2009 the authors404 ta b le 1 p re se n ce /a b se n ce m at ri x o f th e sp e ci e s re co rd e d in th e d if fe re n t ar e as o f th e a n ta rc ti c co n si d e re d in th is st u d y. t h e b io g e o g ra p h ic al ar e as fo llo w b ri g g s (1 9 9 5 ), an d ar e as b e yo n d th e a n ta rc ti c ar e in cl u d e d . t h e 1 0 se ct o rs o f th e a n ta rc ti c re g io n ar e se t in b o ld fa ce . s e e fi g . 2 fo r th e ab b re vi at io n s lis t. pant bel ros wil mau wed sor ssa sge bou sas san tas snz saf as tg sae saw tpe ipw sau nnz jap bpw bpe cal gui am bae car atw a p lid iu m a n n u la tu m (s lu it e r, 1 9 0 6 ) ✓ a p lid iu m a u ro ra e (h ar an t & v e rn iè re s, 1 9 3 8 ) ✓ ✓ ✓ ✓ a p lid iu m b a lle n ia e m o n n io t & m o n n io t, 1 9 8 3 ✓ ✓ ✓ a p lid iu m b ili n g u a e m o n n io t & m o n n io t, 1 9 8 3 ✓ ✓ ✓ a p lid iu m ci rc u m vo lu tu m (s lu it e r, 1 9 0 0 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ a p lid iu m cy a n e u m (s lu it e r, 1 9 0 6 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ a p lid iu m fa lk la n d ic u m m ill ar , 1 9 6 0 ✓ ✓ ✓ ✓ ✓ ✓ ✓ a p lid iu m fu e g ie n se c u n n in g h am , 1 8 7 1 ✓ ✓ ✓ ✓ ✓ a p lid iu m g lo b o su m (h e rd m an , 1 8 8 6 ) ✓ ✓ ✓ ✓ ✓ a p lid iu m im b u tu m m o n n io t & m o n n io t, 1 9 8 3 ✓ ✓ ✓ ✓ ✓ ✓ a p lid iu m lo n g ic a u d a tu m (s lu it e r, 1 9 1 2 ) ✓ a p lid iu m lo ri ca tu m (h ar an t & v e rn iè re s, 1 9 3 8 ) ✓ ✓ ✓ ✓ a p lid iu m m e ri d ia n u m (s lu it e r, 1 9 0 6 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ a p lid iu m m ill a ri m o n n io t & m o n n io t, 1 9 9 4 ✓ ✓ a p lid iu m m ir ip a rt u m m o n n io t & m o n n io t, 1 9 8 3 ✓ a p lid iu m o rd in a tu m (s lu it e r, 1 9 0 6 ) ✓ ✓ a p lid iu m p a e ss le ri (m ic h ae ls e n , 1 9 0 7 ) ✓ ✓ a p lid iu m ra d ia tu m (s lu it e r, 1 9 0 6 ) ✓ ✓ ✓ ✓ a p lid iu m re cu m b e n s (h e rd m an , 1 8 8 6 ) ✓ ✓ ✓ ✓ ✓ a p lid iu m si d e ru m m o n n io t & m o n n io t, 1 9 8 3 ✓ a p lid iu m st a n le yi m ill ar , 1 9 6 0 ✓ ✓ ✓ a p lid iu m st ew a rt e n se (m ic h ae ls e n , 1 9 2 4 )a a p lid iu m tr ip le x (s lu it e r, 1 9 0 6 ) ✓ ✓ a p lid iu m va n h o e ff e n ih ar tm e ye r, 1 9 1 1 a a p lid iu m va ri a b ile (h e rm an , 1 8 8 6 ) ✓ ✓ ✓ ✓ ✓ a p lid iu m va st u m (s lu it e r, 1 9 1 2 ) ✓ ✓ p la ce n te la tr a n sl u ci d a k o tt , 1 9 6 9 ✓ p o ly cl in u m su n d a ic u m (s lu it e r, 1 9 0 9 )a r it te re lla m ir ifi ca m o n n io t & m o n n io t, 1 9 8 3 ✓ ✓ s yn o ic u m a d a re a n u m (h e rd m an , 1 9 0 2 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ s yn o ic u m g e o rg ia n u m s lu it e r, 1 9 3 2 ✓ ✓ ✓ ✓ ✓ ✓ ✓ s yn o ic u m g ia rd i( h e rd m an , 1 8 8 6 ) ✓ ✓ ✓ s yn o ic u m h yp u rg o n (m ic h ae ls e n , 1 9 2 4 ) ✓ ✓ ✓ ✓ s yn o ic u m o st e n to r m o n n io t & m o n n io t, 1 9 8 3 ✓ ✓ ✓ s yn o ic u m p o ly g yn a m o n n io t & m o n n io t, 1 9 8 0 ✓ ✓ ✓ s yn o ic u m ra m u lo su m k o tt , 1 9 6 9 ✓ c ys to d yt e s a n ta rc ti cu s s lu it e r, 1 9 1 2 ✓ ✓ ✓ d is ta p lia co lli g a n s s lu it e r, 1 9 3 2 ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ d is ta p lia cy lin d ri ca (l e ss o n , 1 8 3 0 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ p o ly ci to r cl a va (h ar an t & v e rn iè re s, 1 9 3 8 )a antarctic ascidiansc. primo & e. vázquez polar research 28 2009 403–414 © 2009 the authors 405 ta b le 1 c o n ti n u e d pant bel ros wil mau wed sor ssa sge bou sas san tas snz saf as tg sae saw tpe ipw sau nnz jap bpw bpe cal gui am bae car atw eu d is to m a m a g a lh a e n se (m ic h ae ls e n , 1 9 0 7 ) ✓ ✓ ✓ ✓ s ig ill in a m o e b iu si (h ar tm e ye r, 1 9 0 5 ) ✓ ✓ ✓ s yc o zo a a n o m a la m ill ar , 1 9 6 0 ✓ ✓ s yc o zo a g a im a rd i( h e rd m an , 1 8 8 6 ) ✓ ✓ ✓ ✓ s yc o zo a g e o rg ia n a (m ic h ae ls e n , 1 9 0 7 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ s yc o zo a si g ill in o id e s le ss o n , 1 8 3 0 ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ te tr a zo n a ci e m a ri p ri m o & v áz q u e z 2 0 0 7 ✓ te tr a zo n a g la re o sa (s lu it e r, 1 9 0 6 ) ✓ ✓ ✓ d id e m n u m b e n ta rt iv ar e la & r am o ses p lá 2 0 0 8 ✓ d id e m n u m b ig la n s (s lu it e r, 1 9 0 6 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ d id e m n u m st u d e ri h ar tm e ye r, 1 9 1 1 ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ d id e m n u m te n u e (h e rd m an , 1 8 8 6 ) ✓ ✓ d ip lo so m a a n ta rc ti cu m k o tt , 1 9 6 9 ✓ ✓ d ip lo so m a lis te ri a n u m (m iln e -e d w ar d s, 1 8 4 1 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ d ip lo so m a lo n g in q u u m (s lu it e r, 1 9 1 2 ) ✓ ✓ p o ly sy n cr a to n tr iv o lu tu m (m ill ar , 1 9 6 0 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ c io n a a n ta rc ti ca h ar tm e ye r, 1 9 1 1 ✓ ✓ ✓ ty lo b ra n ch io n sp e ci o su m h e rd m an , 1 8 8 6 ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ c ib a ca p sa g u lo sa m o n n io t & m o n n io t, 1 9 8 3 ✓ ✓ ✓ m e g a lo d ic o p ia h ia n s o ka , 1 9 1 8 a c o re lla e u m yo ta tr au st e d t, 1 8 8 2 ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ a g n e zi a a rn a u d im o n n io t & m o n n io t, 1 9 7 4 ✓ ✓ ✓ a g n e zi a b is co e im o n n io t & m o n n io t, 1 9 8 3 ✓ ✓ ✓ ✓ ✓ ✓ c a e n a g n e si a b o ck ia rn b ac k, 1 9 3 8 ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ c a e n a g n e si a sc h m it ti k o tt , 1 9 6 9 ✓ ✓ c o ry n a sc id ia cu b a re m o n n io t & m o n n io t, 1 9 9 4 ✓ a sc id ia ch a lle n g e ri h e rd m an ,1 8 8 2 ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ a sc id ia m e ri d io n a lis h e rd m an ,1 8 8 0 ✓ ✓ ✓ ✓ ✓ a sc id ia tr a n sl u ci d a h e rd m an ,1 8 8 0 ✓ ✓ a llo e o ca rp a b ig yn a m o n n io t, 1 9 7 8 ✓ ✓ ✓ a llo e o ca rp a in cr u st a n s (h e rd m an , 1 8 8 6 ) ✓ ✓ c n e m id o ca rp a b a rb a ta v in o g ra d o va , 1 9 6 2 ✓ ✓ ✓ ✓ c n e m id o ca rp a d ry g a ls ki i( h ar tm e ye r, 1 9 1 1 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ c n e m id o ca rp a e p o si m o n io t & m o n n io t, 1 9 9 4 ✓ c n e m id o ca rp a p fe ff e ri (m ic h ae ls e n , 1 8 9 8 ) ✓ ✓ ✓ ✓ ✓ ✓ c n e m id o ca rp a ve rr u co sa (l e ss o n , 1 8 3 0 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ d ic a rp a in si n u o sa (s lu it e r, 1 9 1 2 ) ✓ ✓ ✓ ✓ d ic a rp a tr ic o st a ta (m ill ar , 1 9 6 0 ) ✓ ✓ ✓ ✓ antarctic ascidians c. primo & e. vázquez polar research 28 2009 403–414 © 2009 the authors406 p o ly zo a o p u n ti a le ss o n ,1 8 3 0 ✓ ✓ ✓ ✓ ✓ ✓ ✓ s ty e la g la n s h e rd m an , 1 8 8 1 ✓ ✓ ✓ ✓ ✓ s ty e la m a te rn a m o n n io t & m o n n io t, 1 9 8 3 ✓ ✓ ✓ s ty e la sq u a m o sa h e rd m an 1 8 8 1 ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ s ty e la w a n d e li (s lu it e r, 1 9 1 1 ) ✓ ✓ ✓ ✓ t h e o d o re lla a re n o sa m ic h ae ls e n , 1 9 2 2 ✓ ✓ b a th yp e ra sp le n d e n s m ic h ae ls e n , 1 9 0 4 ✓ ✓ ✓ ✓ ✓ ✓ ✓ p yu ra b o u ve te n si s (m ic h ae ls e n , 1 9 0 4 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ p yu ra d is co ve ry i( h e rd m an , 1 9 1 0 ) ✓ ✓ ✓ ✓ ✓ ✓ ✓ p yu ra g e o rg ia n a (m ic h ae ls e n , 1 8 9 8 ) ✓ ✓ ✓ p yu ra le g u m e n (l e ss o n , 1 8 3 0 ) ✓ ✓ p yu ra ly co p e rd o n m o n n io t & m o n n io t, 1 9 8 3 ✓ p yu ra o b e sa s lu it e r, 1 9 1 2 ✓ ✓ p yu ra p a e ss le ri (m ic h ae ls e n , 1 9 0 0 ) ✓ ✓ p yu ra se to sa (s lu it e r, 1 9 0 5 ) ✓ ✓ ✓ ✓ ✓ p yu ra sq u a m a ta h ar tm e ye r 1 9 1 1 ✓ ✓ ✓ ✓ ✓ ✓ ✓ p yu ra tu n ic a k o tt , 1 9 6 9 ✓ eu g yr a ke rg u e le n e n si s (h e rd m an , 1 8 8 1 ) ✓ ✓ ✓ ✓ eu g yr a p o ly d u ct a (m o n n io t & m o n n io t, 1 9 8 3 ) ✓ ✓ ✓ ✓ ✓ ✓ m o lg u la e n o d is (s lu it e r, 1 9 1 2 ) ✓ ✓ ✓ m o lg u la e u p lic a ta h e rd m an , 1 9 2 2 ✓ ✓ ✓ ✓ ✓ ✓ ✓ m o lg u la g e o rg ia n a m ic h ae ls e n , 1 9 0 0 ✓ ✓ ✓ m o lg u la h o d g so n ih e rd m an , 1 9 1 0 ✓ ✓ ✓ ✓ ✓ ✓ ✓ m o lg u la lo n g iv a sc u la m ill ar , 1 9 8 2 ✓ ✓ m o lg u la m a ri o n im ill ar , 1 9 6 0 ✓ ✓ ✓ m o lg u la m o rt e n se n i( m ic h ae ls e n , 1 9 2 2 ) ✓ ✓ ✓ ✓ ✓ m o lg u la p e d u n cu la ta h e rd m an , 1 8 8 1 ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ m o lg u la p u lc h ra m ic h ae ls e n , 1 9 0 0 ✓ ✓ ✓ m o lg u la p yr ifo rm is h e rd m an , 1 8 8 1 ✓ ✓ ✓ m o lg u la ro b in im ill ar , 1 9 6 0 ✓ ✓ ✓ m o lg u lo id e s b a th yb ia (h ar tm e ye r, 1 9 1 2 ) ✓ m o lg u lo id e s co ro n a tu m m o n n io t, 1 9 7 8 ✓ ✓ p a re u g yr io id e s a rn b a ck a e (m ill ar , 1 9 6 0 ) ✓ ✓ ✓ ✓ ✓ p a ra m o lg u la g re g a ri a (l e ss o n , 1 8 3 0 ) ✓ ✓ ✓ a e xc lu d e d fr o m th e an al ys is b e ca u se o f u n ce rt ai n id e n ti fic at io n . antarctic ascidiansc. primo & e. vázquez polar research 28 2009 403–414 © 2009 the authors 407 islands were grouped with the antarctic peninsula because of their close geographical proximity, and because it has been shown that the two areas are similar in terms of their ascidian faunistic composition (monniot & monniot 1983; ramos-esplá et al. 2005). • the bellingshausen sea sector (bel), from the pant limit to the shirase coast, including peter i øy (peter i island) and the amundsen sea. • the ross sea sector (ros), from the bel limit to cape adare. • the wilkes land sector (wil), from the ros limit to the amery ice shelf; this sector includes the davis sea. • the dronning maud land sector (mau), from the wil limit to cape norvegia. • the weddell sea sector (wed), from the mau limit to the northern tip of the antarctic peninsula; i.e., comprising the east coast of the antarctic peninsula. • the south orkney islands sector (sor). • the south sandwich islands sector (ssa). • the south georgia islands sector (sge). • the bouvetøya (bouvet island) sector (bou). each record was assigned to the sector or sectors where it was cited. in addition, we reviewed the worldwide distribution of each species, and assigned them to the regions proposed by briggs (1995). regions with no records were not included in the analysis. areas were classified by cluster analysis, using the bray-curtis similarity coefficient for binary data and the unweighted pair-group method with arithmetic mean (upgma) aggregation algorithm; the results of the classification were combined with multi-dimensional scaling (mds) ordination to confirm the groups obtained. the bray-curtis similarity coefficient for binary data (also known as the sørensen similarity coefficient) gives less weighting to outliers (mccune & grace 2002), thereby minimizing the errors derived from the different quantities of data. analyses were run using primer 5 (plymouth routines in multivariate ecological research). in addition, a similarity matrix was constructed using the kulczynski-2 index, to compare our results with those previously obtained by monniot & monniot (1983) and tatián et al. (2005). the data set was therefore slightly modified, as monniot & monniot (1983) only considered wil to be the coast of the antarctic continent, between 130–170°e, because of the low sampling effort in the remaining areas, and they did not include bel, mau and bou for the same reason. this matrix was constructed using spss 16.0 (statistical package for the social sciences). the percentage abundance of species per biogeographical category was also calculated from the presence/absence matrix (table 1). the biogeographical categories are defined here as faunistic groups, depending on the world distribution of the species beyond the limits of the biogeographical regions considered in the present study. the categories included in the analysis are shown in table 2. results the classification analysis of all marine biogeographical areas (fig. 2) showed all of the antarctic sectors to be clustered together. however, most of the continental sectors were grouped with a high similarity index (55%), whereas bou and bel were less closely related (20% similarity). the sge showed a relationship (60% similarity) with the south america and sub-antarctic regions: with the first region comprising the south american coast from the chiloé islands to peninsula valdés, including the falkland islands, and the second region comprising the kerguelen, heard, crozet, marion, prince edward and macquarie islands (briggs 1995) (fig. 1). the ssa also appeared to be related to this group, but with a lower similarity (40%). all other biogeographical areas appeared to be clustered together; these regions were not at all related to the antarctic region (fig. 2), and were not included in the following analysis. the mds ordination (fig. 3) was carried out to compare the clusters obtained in the classification analysis. the classification analysis on its own can lead to misleading results, as it will give rise to a hierarchy (clusters) whether the variables are hierarchically interrelated table 2 description of the biogeographical categories under consideration. biogeographical component distribution sector endemisms considered sector antarctic endemisms antarctic region (two or more sectors) antarctic–south american antarctic and south america regions, sometimes extending their distribution to the sub-antarctic region cosmopolitan most of the global regions southern hemisphere broad distribution in the southern hemisphere cold regions cold and cold–temperate regions in the southern hemisphere antarctic–sub-antarctic antarctic and sub-antarctic regions antarctic–southern new zealand antarctic and southern new zealand regions, sometimes extending their distribution to the sub-antarctic region antarctic–tasmanian antarctic and tasmanian regions, sometimes extending their distribution to the sub-antarctic region antarctic–southern african antarctic and southern africa regions, sometimes extending their distribution to the sub-antarctic region antarctic ascidians c. primo & e. vázquez polar research 28 2009 403–414 © 2009 the authors408 or not. it can also create different configurations from the same similarity matrix (legendre & legendre 1998). the mds ordination was carried out only considering the antarctic sectors, and the sub-antarctic and south america regions (fig. 3). the mds ordination (stress 0.03) revealed a latitudinal gradient. except for bel, the continental sectors appeared to be closely related and associated with the antarctic peninsula that links the continent with the insular sectors of sor and sge. the sge neither grouped with the other antarctic sectors, nor with the south america and sub-antarctic regions (although it was more closely related to these). it may represent a link between both groups. again, the bou was separated from the rest, and the ssa was also quite distant, although it was closer to the other antarctic sectors than bou. excepting bel and bou, which both had a very low number of ascidian citations (10 and eight, respectively), the antarctic sectors had similar abundance percentages for all of the biogeographical categories (table 3). the antarctic endemic species category was one of the best represented groups in every case (25–51%), whereas the percentage of sector endemism was small or null, thereby corroborating the ascidian fauna homogeneity in the antarctic continent. it is remarkable that despite the antarctic region as a whole having 44% of endemic species (primo & vázquez 2007a), the number of endemic species in each sector was always lower than 10%. the antarctic–south american group was also well represented in all of the sectors considered (especially in the scotia arc islands), indicating a close relationship between both regions. using the kulczynski-2 similarity index, faunistic affinities were calculated and compared with those obtained by monniot & monniot (1983) and tatián et al. (2005), in order to assess the evolution of the ascidian fauna in the antarctic region (table 4). we found an increase in the affinity between sectors in all instances. the affinity between wed and all other sectors was particularly high, as was the affinity between sge and sor. discussion the most obvious pattern observed in the dendrogram (fig. 2), and in the three-dimensional diagram (fig. 3), is the separation of the sectors bel, bou and ssa from the other antarctic sectors. the low sampling effort in the bellingshausen sea is the most probable reason for the separation of this sector. collections made from recent spanish cruises on board the rv hespérides (bentart 2003 and bentart 2006) would help to elucidate the biogeographical relationships, but no results have yet been published for ascidians, except for the description of fig. 2 bray-curtis classification analysis. abbreviations: bou, bouvetøya; bel, bellingshausen sea; mau, dronning maud land; ros, ross sea; wed, weddell sea; wil, wilkes land; pant, antarctic peninsula; sor, south orkney islands; ssa, south sandwich islands; san, sub-antarctic region; sge, south georgia islands; sas, south america region; saw, western south america region; as, amsterdam–saint paul; tg, tristan da cunha; ipw, indo-west pacific region; bae, eastern atlantic boreal region; car, carolina region; jap, japan region; am, mediterranean–atlantic region; tpe, eastern pacific region; bpe, eastern pacific boreal region; bpw, western pacific boreal region; cal, california region; gui, eastern atlantic region; atw, western atlantic region; snz, southern new zealand region; nnz, northern new zealand region; sae, eastern south america region; sau, southern australia region; tas, tasmania region; saf, southern africa region. antarctic ascidiansc. primo & e. vázquez polar research 28 2009 403–414 © 2009 the authors 409 a new didemnidae species (varela & ramos-esplá 2008). bouvetøya is a geologically young and isolated island, located to the south of the polar front, and was separated from neighbouring areas in the analysis because of the low sampling effort in this sector (primo & vázquez 2007a). however, a recent expedition to this island confirmed the impoverished ascidian fauna—only seven species were found (arntz et al. 2006)—whereas in other taxonomical groups the number of species has increased substantially in recent years. the south sandwich islands is a relatively young archipelago of volcanic origin, just south of the polar front, and is the most remote scotia arc archipelago from both south america and antarctica (zelaya 2005). this could explain the separation of this fig. 3 multi-dimensional scaling ordination analysis of antarctic sectors, the sub-antarctic region and the south america region. table 3 percentage of the biogeographical categories in the 10 antarctic sectors considered. abbreviations: se, sector endemism; ae, antarctic endemism; a–sam, antarctic–south american; c, cosmopolitan; sh, southern hemisphere; cr, cold regions; a–san, antarctic–sub-antarctic; a–tas, antarctic–tasmanian; a–snz, antarctic–southern new zealand; a–saf, antarctic–southern african. se ae a–sam c sh cr a–san a–tas a–snz a–saf antarctic peninsula 10 42 26 3 11 1 3 0 3 0 belligshausen sea 10 40 20 0 10 0 20 0 0 0 ross sea 0 51 23 5 10 0 5 0 5 0 wilkes land 5 43 23 7 14 0 5 0 5 0 dronning maud land 5 37 32 0 16 0 5 0 5 0 weddell sea 5 40 23 5 13 0 10 0 5 0 south orkney islands 0 36 33 5 18 3 3 0 5 0 south sandwich islands 0 32 40 0 12 0 12 0 0 4 south georgia islands 0 25 36 4 20 2 9 0 4 2 bouvetøya 0 25 25 0 25 13 0 0 13 0 table 4 kulczynski-2 similarity index (percentage) between different sectors. abbreviations: mm, monniot & monniot (1983); ta, tatián et al. (2005); ps, present study; nd, no data. antarctica peninsula ross sea wilkes land weddell sea s. orkney s. sandwich mm ta ps mm ta ps mm ta ps mm ta ps mm ta ps mm ta ps ross sea 65 nd 72 — — — — — — — — — — — — — — — wilkes land 64 nd 62 61 nd 54 — — — — — — — — — — — — weddell sea 54 nd 67 59 nd 76 52 nd 45 — — — — — — — — — s. orkney 65 69 73 61 nd 58 65 nd 59 43 nd 53 — — — — — — s. sandwich 44 45 52 33 nd 43 42 nd 36 26 nd 42 43 41 42 — — — s. georgia 47 48 51 47 nd 52 41 nd 49 40 nd 49 44 45 58 49 47 43 antarctic ascidians c. primo & e. vázquez polar research 28 2009 403–414 © 2009 the authors410 sector in the analyses. the separation of the ssa was already observed for ascidians by monniot & monniot (1983), who suggested a decrease in antarctic influence without a rise in south american influence as the most likely reason for this result. recent papers (ramos-esplá et al. 2005; tatián et al. 2005) have also reported a difference in the species composition of this archipelago, although this appeared to be more closely related to the south georgia islands than is found in the present work. the remaining areas appear to be more closely related. moreover, there appears to be a difference in the specific composition between continental and insular sectors (fig. 3), and the geographical distance is the most likely reason for this. on the other hand, the insular sectors, and especially south georgia island, are closer to the south america and sub-antarctic regions. similarly, tatián et al. (2005) assumed that the polar front was situated south of this archipelago. south georgia island seems to be an overlapping area for ascidian fauna (monniot & monniot 1983; ramos-esplá et al. 2005; primo & vázquez 2007a), although it appears to be more closely connected to the antarctic region (primo & vázquez 2007a). the grouping of most of the antarctic sectors suggests a great homogeneity of the antarctic ascidian fauna, especially in the continental sectors. even the ascidian fauna of the ross and weddell seas appear to be closely related to each other, in spite of the presence of the antarctic peninsula and bellingshausen sea between them. a possible explanation for this similarity is the presence of a seaway linking both seas, but separating them from the micro-continental fragments that would later form the antarctic peninsula and scotia arc islands (lawver & gahagan 2003; linse et al. 2007). the homogeneity of the antarctic ascidian fauna could also be a consequence of the relative constancy of the physical conditions (except for light) in the antarctic region (arntz et al. 1994), as well as the effect of the circum-antarctic currents (the east and west wind drifts), which favour the dispersal of organisms around the whole region (linse et al. 2007; barnes & griffiths 2008). in addition to this, the isolation by deep sea and the antarctic convergence, which impedes the mixing with fauna from other regions, may also contribute to the unification of the antarctic ascidian fauna. nevertheless, the faunistic exchange is not equal across the entire region (arntz et al. 1994). the insular sectors show a closer relationship with the south american fauna, probably because of geographical proximity. the distribution of biogeographical categories in the sectors considered confirmed the results of the classification and ordination analyses. first, a high percentage of endemic species in the whole antarctic region and a low percentage of sector endemism (table 3) corroborate the hypothesis of a very homogeneous antarctic ascidian fauna. the fact that every sector (except bel and bou, which both have a low number of species) has similar percentages of biogeographical elements also seems to support this theory. evolution may be extremely slow under cold antarctic conditions (ingels et al. 2006), where animals live long and reproduce slowly (arntz et al. 1994), and there may not have been enough time for a significant endemic fauna to develop in these sectors (glasby & alvarez 1999; barnes & griffiths 2008). even the proportion of antarctic–south american species, although slightly higher in the island sectors, is also similar in all sectors, confirming the homogeneity of this fauna, and refuting the grouping of south georgia with the south america and sub-antarctic regions observed in the classification analysis. the general increase of faunistic affinities between sectors through time (table 4) also seems to confirm the idea of a very homogeneous antarctic ascidian fauna. the more we learn about this fauna, the more homogenous it seems to be. this idea is also supported by the decrease in the percentage of sector endemism, from a maximum of 15% in the antarctic peninsula, found by monniot & monniot (1983), to 10% in the present study. nevertheless, the fact that there is a greater increment of faunistic affinities in the wed than in other sectors may be a consequence of our improved knowledge of this sector (from 11 species cited by monniot & monniot [1983] to 40 species in the present study). on the other hand, the substantial similarity of the sge to the sor, when compared with monniot & monniot (1983) and tatián et al. (2005), seems to support the idea that the south georgia ascidian fauna is more closely related to that of the antarctic region than is shown in the cluster analysis, although we observed a gradient along the scotia arc, as did tatián et al. (2005). several recent studies on the zoogeography of the antarctic region have been carried out, although different methods of analyses were used for different taxa: comparing them is not easy. most of these studies considered the antarctic region as the whole area south of the antarctic convergence, but very different divisions were chosen, ranging from no divisions at all (mysids, brandt et al. [1998]; hydroids, peña-cantero & garcía carrascosa [1999]) to seven, 12 or 15 subregions (cumaceans, mühlenhardt-siegel [1999]; molluscs, linse et al. [2006]; bryozoans, barnes & griffths [2008]), with different limits. some of the studies excluded all or part of the scotia arc islands (isopods, brandt et al. [1999]; ascidians, ramos-esplá et al. [2005]), or included the subantarctic islands in some of the analyses (barnes & griffiths 2008). although the results differ among the antarctic ascidiansc. primo & e. vázquez polar research 28 2009 403–414 © 2009 the authors 411 studies, in general, the antarctic continent (or continental sectors) and scotia arc islands were grouped together, whereas bouvetøya, south georgia and the south sandwich islands have an uncertain position in some cases (ramos-esplá et al. 2005; linse et al. 2006). the percentage of endemic species in the antarctic region for benthic invertebrates is usually high. it varies from 35% (scleractinian corals; arntz et al. [1997]) to 95% (pycnogonids, jazdzewski et al. [1991]), although a decreasing percentage has been found for the same taxa over time. for example, jazdzewski et al. (1991) reported 95% endemism for amphipods, and de broyer et al. (2007) reported 72% endemism for the same group of animals. barnes & de grave (2000) reported 83% endemism among bryozoans; this figure went down to 57% eight years later (barnes & griffiths 2008). the decrease of endemism could indicate that antarctica has been less isolated over geological time than was once thought (barnes & griffiths 2008). this is not the case for ascidians, as the percentage of endemic species seems to remain quite constant, ranging from 51% (monniot & monniot 1983) to 44% (primo & vázquez 2007a). as for the sector endemism, barnes & griffiths (2008) also found a low level of endemism for bryozoans, and suggested the west wind drift current as the most probable agent of dispersion that may explain this pattern. other groups showed a completely different pattern, with a high level of endemism in some sectors, and lower endemism in others (brandt et al. 1999; mühlenhardtsiegel 1999; linse et al. 2006). as a final point, we should not forget the potential contribution of anthropogenic introductions to the southern ocean. several ascidian species that are found in antarctic waters have a wide distribution (e.g., sigillina moebiusi, diplosoma listerianum, corella eumyota and styela squamosa), and it may not be appropriate to assume that these species (or any other marine species) are natives. although little is known about the present rate of establishment of non-indigenous marine species in the southern ocean, shipping has the potential to introduce non-native species into a marine environment that is known to have very high degrees of endemism. the probability of transport of invasive species into the southern ocean may increase in the future, as a consequence of the growth in tourism, fisheries and science activities in the region (lewis et al. 2003), and fouling organisms would seem to be the likely first candidates (barnes & griffiths 2008). ascidians, as a common component of the fouling communities on the hulls of ships (carlton 1989; coutts 1999; gollasch & leppakoski 1999; floerl et al. 2005; lambert 2007), are one of the most probable taxa to be introduced in this region. also, as factors limiting successful invasions are frequently related to physical characteristics such as temperature, a future global warming would enable new taxa to become established (lewis et al. 2003; clarke et al. 2005). the growth of some invasive ascidian species is affected by temperature (agius 2007), so a rise in sea-surface temperatures may facilitate the invasion of non-native ascidian species; a significant warming has been already detected around the antarctic peninsula (meredith & king 2005; turner et al. 2005). however, no marine non-indigenous animal species have yet been proven to have become successfully established in antarctic waters (thatje 2005; barnes et al. 2006). acknowledgements we thank dr jeff wright for his helpful suggestions and revision of the english, and the valuable comments of two anonymous reviewers. this study was financed by a pre-doctoral fellowship to c. primo from xunta de galicia. references agius b.p. 2007. spatial and temporal effects of pre-seeding plates with invasive ascidians: growth, recruitment and community composition. journal of experimental marine biology and ecology 342, 30–39. arntz w.e., brey t. & gallardo v.a. 1994. antarctic zoobenthos. in h. barnes et al. (eds.): oceanography and marine biology: an annual review. vol. 32. pp. 241–304. london: taylor & francis. arntz w.e., gutt j. & klages m. 1997. antarctic marine biodiversity: an overview. in b. battaglia et al. (eds.): antarctic communities: species, structure and survival. pp. 3–14. cambridge: cambridge university press. arntz w.e., thatje s., linse k., avila c., ballesteros m., barnes d.k.a., cope t., cristobo f.j., de broyer c., gutt j., isla e., lópez-gonzález p., montiel a., munilla t., ramos-esplá a.a., raupach m., rauschert m., rodríguez e. & teixidó n. 2006. missing link in the southern ocean: sampling the marine benthic fauna of remote bouvet island. polar biology 29, 83–96. barnes d.k.a. & de grave s. 2000. biogeography of southern polar bryozoans. vie et milieu 50, 261–273. barnes d.k.a. & griffiths h.j. 2008. biodiversity and biogeography of southern temperate and polar bryozoans. global ecology and biogeography 17, 84–99. barnes d.k.a., hodgson d.a., convey p., allen c.s. & clarke a. 2006. incursion and excursion of antarctic biota: past, present and future. global ecology and biogeography 15, 121–142. brandt a., linse k. & mühlenhardt-siegel u. 1999. biogeography of crustacea and mollusca of the subantarctic and antarctic regions. scientia marina 63, 383–389. antarctic ascidians c. primo & e. vázquez polar research 28 2009 403–414 © 2009 the authors412 brandt a., mühlenhardt-siegel u. & siegel v. 1998. an account of the mysidacea (crustacea, malacostraca) of the southern ocean. antarctic science 10, 3–11. briggs j.c. 1995. global biogeography. developments in palaeontology and stratigraphy. amsterdam: elsevier. carlton j.t. 1989. man’s role in changing the face of the ocean: biological invasions and implications for conservation of nearshore environments. conservation biology 3, 265–273. clarke a., aronson r.b., crame j.a., gili j.m. & blake d.b. 2004. evolution and diversity of the benthic fauna of the southern ocean continental shelf. antarctic science 16, 559–568. clarke a., barnes d.k.a. & hodgson d.a. 2005. how isolated is antarctica? trends in ecology and evolution 20, 1–3. cloney r.a., young c.m. & svane i. 2002. phylum chordata: urochordata. in c.m. young et al. (eds.): atlas of marine invertebrates larvae. pp. 565–593. london: academic press. coutts a.d.m. 1999. hull fouling as a modern vector for marine biological invasions: investigation of merchant vessels visiting northern tasmania. ms thesis, australian maritime college. de broyer c., lowry j.k., jazdzewski k. & robert h. 2007. census of antarctic marine life. synopsis of the amphipoda of the southern ocean. bulletin de l’institut royal des sciences naturelles de belgique, biologie 77. brussels: institut royal royal des sciences naturelles de belgique. floerl o., inglis g.j. & marsh h.m. 2005. selectivity in vector management: an investigation of the effectiveness of measures used to prevent transport of non-indigenous species. biological invasions 7, 459–475. glasby c.j. & alvarez b. 1999. distribution patterns and biogeographic analysis of austral polychaeta (annelida). journal of biogeography 26, 507–533. gollasch s. & leppakoski e. 1999. initial risk assessment of alien species in nordic coastal waters. copenhagen: nordic council of ministers. ingels j., vanhove s., de mesel i. & vanreusel a. 2006. the biodiversity and biogeography of the free-living nematode genera desmodora and desmodorella (family desmodoridae) at both sides of the scotia arc. polar biology 29, 936–949. jazdzewski k., teodorczyk w., sicinsky j. & kontek b. 1991. amphipod crustaceans as an important component of zoobenthos of the shallow antarctic sublittoral. hydrobiologia 223, 105–117. knox g.a. 2007. biology of the southern ocean. 2nd edn. boca raton, fl: crc press. kott p. 1969. antarctic ascidiacea. a monographic account of the known species based on specimens collected under u.s. government auspices, 1947–1965. antarctic research series 13. washington, d.c.: american geophysical union. lambert g. 2007. invasive sea squirts: a growing global problem. journal of experimental marine biology and ecology 342, 3–4. lawver l.a. & gahagan l.m. 2003. evolution of cenozoic seaways in the circum-antarctic region. palaeogeography, palaeoclimatology, palaeoecology 198, 11–37. legendre p. & legendre l. 1998. numerical ecology. 2nd english edn. amsterdam: elsevier. lewis p.n., hewitt c.l., riddle m. & mcminn a. 2003. marine introductions in the southern ocean: an unrecognised hazard to biodiversity. marine pollution bulletin 46, 213–223. linse k., cope t., lörz a.n. & sands c. 2007. is the scotia sea a centre of antarctic marine diversification? some evidence of cryptic speciation in the circum-antarctic bivalve lissarca notorcadensis (arcoidea: philobrydae). polar biology 30, 1059–1068. linse k., griffiths h.j., barnes d.k.a. & clarke a. 2006. biodiversity and biogeography of antarctic and subantarctic mollusca. deep-sea research part ii 53, 985–1008. longhurst a. 1998. ecological geography of the sea. san diego: academic press. mccune b. & grace j.b. 2002. analysis of ecological communities. gieneden beach, or: mjm sofware design. meredith m.p. & king j.c. 2005. rapid climate changein the ocean to the west of the antarctic peninsula during the second half of the 20th century. geophysical research letters 32, l19604, doi: 10.1029/2005gl024042. millar r.h. 1960. ascidiacea. discovery reports. vol. 30. london: cambridge university press. monniot c. & monniot f. 1982. some antarctic deep-sea tunicatesin the smithsonian collections. antarctic research series 32, 95–130. monniot c. & monniot f. 1983. ascidies antarctiques et subantarctiques: morphologie et biogéographie. (antarctic and subantarctic ascidians: morphology and biogeography). mémoires du muséum national d’histoire naturelle, paris, a, 125. paris: editions du muséum. monniot c. & monniot f. 1994. ascidians collected in the weddell sea by the rv “polarstern” (epos cruise leg 3). bulletin du museum national d’histoire naturelle, paris 16, 13–37. mühlenhardt-siegel u. 1999. on the biogeography of cumacea (crustacea, malacostraca). a comparison between south america, the subantarctic islands and antarctica: present state of the art. scientia marina 63, 295–302. peña-cantero a.l. & garcía carrascosa a.m. 1999. biogeographical distribution of the benthic thecate hydroids collected during the spanish “antártida 8611” expedition and comparison between antarctic and magellan benthic hydroid faunas. scientia marina 63, 209–218. primo c. 2006. taxonomía y biogeografía de la clase ascidiacea en las regiones antártica y subantárticas. (taxonomy and biogeography of the class ascidiacea in antarctic and sub-antarctic regions.) phd thesis, university of vigo. primo c. & vázquez e. 2007a. zoogeography of the antarctic ascidian fauna in relation to the sub-antarctic and south america. antarctic science 19, 321–336. antarctic ascidiansc. primo & e. vázquez polar research 28 2009 403–414 © 2009 the authors 413 primo c. & vázquez e. 2007b. ascidians collected during the antarctic spanish expedition ciemar 99/00 in the bransfield and gerlache straits. journal of natural history 41, 1775–1810. ramos-esplá a.a., cárcel j.a. & varela m. 2005. zoogeographical relationships of the littoral ascidiofauna around the antarctic peninsula, in the scotia arc and in the magellan region. scientia marina 69, 215–223. saiz j.i., garcía f.j., manjón-cabeza m.e., parapar j., peña-cantero a., saucède t., troncoso j.s. & ramos a. 2008. community structure and spatial distribution of benthic fauna in the bellingshausen sea (west antarctica). polar biology 31, 735–743. sanamyan k.e. & sanamyan n.p. 2002. deep-water ascidians from the south-western atlantic (rv dmitry mendeleev, cruise 43, and rv academic kurchatov, cruise 11). journal of natural history 36, 305–359. sluiter c.p. 1906. tuniciers. (tunicates.) expédition antarctique française (1903–1905). vol. 6. paris: masson. strathmann r.r., kendall r.l. & marsh a.g. 2006. embryonic and larval development of a cold adapted antarctic ascidian. polar biology 29, 495–501. tatián m., antacli j.c. & sahade r. 2005. ascidians (tunicata, ascidiacea): species distribution along the scotia arc. scientia marina 69, 205–214. tatián m., sahade r.j., doucet m.e. & esnal g.b. 1998a. ascidians (tunicata, ascidiacea) of potter cove, south shetland islands, antarctica. antarctic science 10, 147– 152. tatián m., sahade r.j., doucet m.e. & esnal g.b. 1998b. some aspects of antarctic ascidians (tunicata, ascidiacea) of potter cove, king george island. berichte zur polarforschung 299, 113–118. thatje s. 2005. the future fate of the antarctic marine biota? trends in ecology and evolution 20, 418–419. troncoso j.s., aldea c., arnaud p., ramos a. & garcía f. 2007. quantitative analysis of soft-bottom molluscs in the bellingshausen sea and around peter i island. polar research 26, 126–134. turner j., colwell s.r., marshall g.j., lachlan-cope t.a., carleton a.m., jones p.d., lagun v., reid p.a. & iagovkina s. 2005. antarctic climate change during the last 50 years. international journal of climatology 25, 279–294. varela m.m. 2007. contribución al conocimiento de las ascidias coloniales (chordata: tunicata) de la antártida occidental y región magallánica. (contribution to the knowledge of colonial ascidians [chordata: tunicata] from western antarctica and the magellanic region.) phd thesis, university of alicante. varela m.m. & ramos-esplá a. 2008. didemnum bentarti (chordata: tunicata) a new species from the bellingshausen sea, antarctica. polar biology 31, 209–213. zelaya d.g. 2005. the bivalves from the scotia arc islands: species richness and faunistic affinities. scientia marina 69, 113–122. antarctic ascidians c. primo & e. vázquez polar research 28 2009 403–414 © 2009 the authors414 no job name observing snowmelt dynamics on fast ice in kongsfjorden, svalbard, with noaa/avhrr data and field measurements sascha willmes,1 jörg bareiss,1 christian haas2 & marcel nicolaus3 1 department of environmental meteorology, behringstrasse 21, campus ii, university of trier, de-54286 trier, germany 2 department of earth & atmospheric sciences, 1–26 earth sciences building, university of alberta, edmonton, alberta t6g 2eg, canada 3 norwegian polar institute, polar environmental centre, no-9296 tromsø, norwaypor_095 203..213 abstract temporal snowmelt dynamics on fast ice in kongsfjorden/svalbard are studied for the period 1990–2003, using visible and near-infrared channels of the advanced very high resolution radiometer (avhrr). long-term radiation data from an adjacent baseline surface radiation network station, as well as extensive glaciological and meteorological field measurements on the melting ice in 2002 and 2003, are used to validate a snowmelt index derived from the satellite data. this study shows that the remote sensing data are in good agreement with the field observations. however, the temporal variability of atmospheric water vapour has an impact on the snowmelt index, and must be accounted for through atmospheric correction. the analysis of long-term satellite data provides valuable insight into the strength and rate of the snowvolume decay, and reveals a strong interannual variability of the snowmelt intensity. however, a precise date for determining melt onset requires clear-sky avhrr data throughout the onset period. keywords climate variability; remote sensing; sea ice; snowmelt detection; svalbard. correspondence sascha willmes, department of environmental meteorology, behringstrasse 21, campus ii, university of trier, de-54286 trier, germany. e-mail: willmes@uni-trier.de doi:10.1111/j.1751-8369.2009.00095.x the seasonal variability of sea ice, and its snow cover, is a key parameter for the investigation of the role of polar regions in climate change scenarios. changes in sea-ice cover are capable of triggering and amplifying global climate changes (curry et al. 1995). sea ice is characterized by high temporal variability, and the overlying snow is very sensitive to atmospheric and radiative forcing. knowledge of the seasonal snow-cover dynamics is essential to understand the formation and decay of sea ice. snowmelt dynamics represent an important factor for the sea-ice mass balance, where meltwater percolating downwards triggers the formation of superimposed ice (nicolaus et al. 2003; kawamura et al. 1997). a very low thermal conductivity causes the snow cover to effectively suppress the energy exchange at the ocean–ice– atmosphere boundary. moreover, the extinction of photosynthetically active radiation makes snow a limiting factor for biological primary production under the ice (gerland et al. 1999). the surface processes taking place during the transition from winter to summer are combined with a large albedo decrease, and consequently affect the regional surface heat budget (holt & digby 1995; perovich et al. 2002). hence, detecting the spatiotemporal variability of snowmelt patterns, and the onset and duration of melting, is crucial with regards to studies of global change. several approaches have been made so far in order to determine the onset of snowmelt through satellite information. data from passive microwave radiometers can be used to identify the formation of meltwater within the snow pack, through a strong increase in surface brightness temperatures (comiso 1983; anderson 1997). drobot & anderson (2001) and belchansky et al. (2004) use this feature to derive arctic-wide snowmelt onset maps for the period 1979–2001. passive microwave satellite data are independent of surface illumination, but have a low spatial resolution compared with optical sensors, so that surface processes in narrow fjords can not be observed with these data. radar sensors (sars) yield a substantially higher resolution, and provide valuable data for snowmelt detection (gogineni et al. 1992). however, their availability for longer time scales is limited. visible and near-infrared satellite imagery provides a convenient compromise of spatial and temporal resolution for the monitoring of snowmelt processes in fjords, as the spectral reflection of snow is significantly modified polar research 28 2009 203–213 © 2009 the authors 203 mailto:willmes@uni-trier.de when intergrain meltwater develops (perovich 1996; de abreu et al. 2001; zhang et al. 2003; winther et al. 2004). de abreu (1996) suggested the use of a twochannel index with advanced very high resolution radiometer (avhrr) data to observe changes in sea-ice and snow surface conditions in the canadian arctic archipelago. the normalized difference snow and ice index (ndsii) utilizes the characteristic changes of the spectral albedo of snow after the formation of meltwater, and thus indicates the onset of the melt. this paper intends to test the ability of the ndsii, as suggested by de abreu (1996), to detect snowmelt on fast ice in the environment of narrow fjords. the area under investigation is kongsfjorden in north-western svalbard. the research settlement of ny-ålesund is located in this fjord, and several adjacent scientific stations have provided ground-based meteorological data continuously since 1993. consequently, this area offers a great opportunity to validate remotely sensed surface information through the permanent presence of high-quality meteorological instrumentation. we assess the ndsii by comparing high-resolution in situ measurements of the physical snow properties on fast ice in kongsfjorden with the coincident index evolution from may to june. the field data were acquired in kongsfjorden during the surface energy budget and its impact on superimposed ice formation (sebisup) field campaigns in 2002 and 2003 (nicolaus et al. 2003). additionally, a 10-year time series from an adjacent meteorological station in ny-ålesund (1993–2003) is used to discuss the index evolution in the melting seasons prior to the years with available ground data. data and methods visible and near-infrared satellite imagery is used to obtain the dynamics of snowmelt on fast ice in kongsfjorden for the period 1990–2003, by means of a normalized difference melt index. to validate the satellite-derived snowmelt patterns, radiation data from a baseline surface radiation network (bsrn) were used along with in situ and meteorological data from the sebisup field experiments. study area the study area of kongsfjorden is about 25 km long and 5–10 km wide. the glacier kongsbreen is situated at the head of the fjord. the bsrn station is located in ny-ålesund on the brøggerhalvøya peninsula at 78.93°n, 11.95°e, on the southern edge of the fjord, at 11 m a.s.l. the physical environment of kongsfjorden was described by svendsen et al. (2002). field measurements during the sebisup campaign were performed on 0.8-m-thick fast ice at konsfjorden, close to the island of gerdøya (78.96°n, 12.26°e), from the middle of may to the beginning of june (fig. 1). this location was selected because the first year fast-ice cover lasts until july, and the snow conditions are representative for eastern kongsfjorden. satellite data daily avhrr polar 1 km level 1b imagery was used to observe snowmelt. local area coverage (lac) data were obtained from the national oceanic and atmospheric fig. 1 (a) map of kongsfjorden showing the location of the measurement site and the fast-ice edges (dotted lines) on 16 may and 6 june 2002 (nicolaus et al. 2003). (b) advanced very high resolution radiometer (avhrr) channel 2 subset image of the same area on 16 may 2002. snowmelt detection in kongsfjorden s. willmes et al. polar research 28 2009 203–213 © 2009 the authors204 administration (noaa) comprehensive large arraydata stewardship system (class) for the period of 1990– 2003. preprocessing of satellite data included geometric and radiometric corrections with terascan software. the spatial resolution of the lac data is 1.1 km ¥ 1.1 km at the centre line of a swathe, degrading to a few kilometres at the swathe edges. on average, 72 satellite images were available in each year for the months of may and june. manual cloud-detection techniques were used to select images without clouds obscuring the kongsfjorden area. to account for a potential influence of the bidirectional reflectance, we skipped images where the area of interest was located at the edge of swathes. normalized difference snow and ice index (ndsii) the normalized difference methods allow long-term studies of broad-scale regions to be made, when complicated modelling of the atmospheric influence is not practicable. in this study, we utilize the ndsii to monitor surface melt processes on sea ice, as suggested by de abreu (1996). the index is computed as follows: ndsii avhrr avhrr avhrr avhrr= −( ) +( )1 2 1 2 (1) dry snow is characterized by a very high spectral albedo, between 400 and 1200 nm, with only a slight decrease towards near-infrared wavelengths. this feature causes very low ndsii values. a reduction in the bulk albedo as well as a higher difference between the avhrr channel 1 (580–680 nm) and the avhrr channel 2 (720–1100 nm) albedos cause an increase of the index. this makes the ndsii sensitive to the magnitude and shape of the albedo spectra. consequently, as the first appearance of liquid water in a snow volume causes a strong albedo drop in near-infrared wavelengths only, the index should respond with a sudden increase, which in turn can be identified as the onset of the melt. moreover, the index is sensitive to the type of input data. the top of the atmosphere (toa) reflectances or, alternatively, the bottom of the atmosphere (boa) reflectances can be used. differences between toaand boa-derived ndsii values are mainly the result of atmospheric water vapour (awv), which affects the atmospheric transmission of wavelenghts in avhrr channel 2. in this study, we estimate the sensitivity of the toa-based index to awv by modelling toa values of the ndsii from estimated boa index values. this is accomplished by applying different atmospheric conditions to the radiative transfer model used in atcpro software (hill & mehl 2003), which includes wavelength-dependent absorption properties of various atmospheric gases, including awv. station data surface radiation data, including the surface radiation budget (r*), were obtained from the bsrn station in ny-ålesund, an international cooperative network set up by the world climate research programme (wcrp). the bsrn station is operated by the alfred wegener institute for polar and marine research (awi), and has been in operation since august 1992. kipp & zonen cm 11 pyranometers are installed to measure the incoming and reflected short-wave radiation at this site. eppley pyrgeometers are used to obtain incoming and outgoing longwave radiation. radiation data with 5-min intervals are provided from march 1992 to july 1998, and with 1-min intervals from august 1998 to june 2003. the temporal variability of the surface energy balance (q*; eq. 2) is a good measure for melt-related surface processes, as changes in radiation and energy fluxes can trigger snow metamorphism, and the formation of meltwater. the surface radiation balance is included in the bsrn data set, but in order to obtain the evolution of the surface energy balance between may and june from 1993 to 2003, turbulent fluxes of latent (qe) and sensible (qh) heat had to be calculated. this was achieved using an aerodynamic approach (launiainen & cheng 1995). the input data for this method are as follows: surface temperatures, which were derived from the long-wave outgoing radiation; wind speed at 10 m above the level of the snow; air temperature and relative humidity at 2 m above the level of the snow; as well as the air pressure at sea level. these data are provided by the norwegian polar institute in their collection of meteorological tower measurements held in ny-ålesund. the conductive heat flux (qc) is assumed to be zero in this study, as the snow and ice volume is close to melting, which means we have nearly isothermal conditions. q r q q q* = + + + ( )−* w mh e c 2 (2) the values of q* were calculated as daily mean values from observations taken every 3 h. for the correction of the satelite data, values of awv were acquired from daily upper-air soundings, performed by awi at koldewey station in ny-ålesund. sebisup data during the sebisup field campaigns in 2002 and 2003, meteorological and glaciological field measurements were performed on the melting fast ice. a meteorological station was equipped with two kipp & zonen cm 22 pyranometers and two eppley pyrgeometers to measure all components of the long-wave and short-wave radiation balance. air temperature, relative humidity, as well snowmelt detection in kongsfjordens. willmes et al. polar research 28 2009 203–213 © 2009 the authors 205 as wind velocity and wind direction 2 m above the snow surface, were measured using an automatic weather station (aws). snow and ice measurements were collected at a distance of about 10 m from the aws. the snow thickness was measured with a horizontal spacing of 1 m along a 50-m representative profile, with the aid of a ruler stick, once a day at noon. vertical profiles of snow temperature and wetness were measured daily along the profile in hourly intervals. the snow temperature was acquired with a hand-held pt-100 thermometer, and snow wetness was measured using a dielectric resonator probe (snow fork; shivola & tiuri 1986) to calculate the percentage of liquid water content. the density of the snow cover was obtained by weighing a defined volume (0.5 l) of snow. the spectral albedo was recorded with a spectron engineering se 590 spectroradiometer at 256 wavelengths between 396 and 1075 nm. additionally, ice cores were drilled on nine days at different positions of the snow-thickness profile to measure sea-ice thickness, as well as vertical profiles of temperature and salinity. the crystal texture was observed by means of thick sections viewed between crossed polarizers (nicolaus et al. 2003). results influence of atmospheric water vapour the avhrr measurements in channels 1 and 2 are both affected by the absorption bands of atmospheric gases. ozone, which is assumed to be constant in time for this study, absorbs some of the radiation that is collected by the visible channel. awv, which is highly variable, lowers the atmospheric transmission in the near infrared. therefore, it is necessary to estimate the sensitivity of the ndsii to the temporal variability of awv. to achieve this, the in situ measured boa albedos of three different surface types (new snow, melting snow and old snow; see table 1) were used to calculate toa albedos for different atmospheric conditions (using awv values from radio soundings). ndsii values were subsequently calculated from the simulated toa albedo to investigate how they change with increasing awv. the results are presented in fig. 2. for awv values that are close to zero, the toa ndsii is lower than the boa ndsii, as a result of ozone absorption in channel 1, and consequently leads to an underestimation of ndsii. the opposite case happens with increasing awv. this implies that a rapid increase of awv in the monitoring period could produce toa ndsii increases that are not related to changes in surface conditions. a polynomial model was fitted to the relationship between awv and the ndsii offset between toa and boa albedo values (fig. 3). subsequently, the ndsii from satellite-measured toa reflectance data was added as an offset, depending on the level of awv for the respective day. from this, we obtained the time series of awv-corrected toa ndsii values for each year from 1990 to 2003, between day of year (doy) 120 (30 april) and 180 (29 june). figure 4 presents a comparison of the corrected and uncorrected ndsii values in a time series of data for the years 2002 and 2003. after correction, the ndsii is generally lower than before. the strong index increase occurring at doy 142 in 2002 was apparently caused by a coincident increase in awv. after the calculated offset was added, the date of the ndsii increase was shifted to doy 147. ndsii and field measurements the ndsii, calculated as a spatial average for the fast-ice area in kongsfjorden between doy 120 (30 april) and table 1 surface albedo in the spectral range of the advanced very high resolution radiometer (avhrr) channels 1 and 2, and coincident normalized difference snow and ice index (ndsii) values for three surface types. data are taken from sebisup 2002 spectral albedo measurements. avhrr channel 1 avhrr channel 2 ndsii new snow 0.96 0.91 0.027 snow (melt onset) 0.93 0.82 0.063 old snow 0.46 0.39 0.082 fig. 2 the normalized difference snow and ice index (ndsii) from the modelled top of the atmosphere (toa) reflectances, plotted against three different bottom of the atmosphere (boa) ndsiis, with changing levels of atmospheric water vapour (awv). the toa reflectances are calculated with atcpro. snowmelt detection in kongsfjorden s. willmes et al. polar research 28 2009 203–213 © 2009 the authors206 180 (29 june), is presented in fig. 4 for the years of 2002 and 2003. both time series show positive trends during the ablation period. the fact that fewer clear-sky images were available for 2003 leads to less available ndsii values. the subsequent discussion is based on the corrected time series shown in fig. 4b. the 2002 ndsii values oscillated at values below 0.1, before increasing sharply to values of 0.14 at doy 147 (27 may), and to even higher values after that. the time series for 2003 appears to be quite different: the ndsii does not exceed 0.05 before doy 162 (11 june). a very weak increase can be found between doy 146 (26 may) and doy 161 (10 june), but the most pronounced rise occurs directly afterwards. the sebisup field campaigns provide measurements of vertical snow temperature, wetness and density profiles from 20 may to 4 june 2002, and from 15 may to 5 june 2003. the first sebisup year (2002) was characterized by a sharp transition from dry to melting snow cover in the sampling period, whereas in 2003 the snow-cover decay was less differentiated (nicolaus 2006). figure 5 summarizes the evolution of snow height and broad-band albedo at the field station for the two years studied. in 2002, the snow cover on fast ice in the middle of may was about 22 cm thick. this snow volume was very stable until the end of may (doy 148), when thickness decreased sharply to pratically zero within just 4 days. snow melt was initiated by a drastic 70 w m-2 increase of the incoming long-wave radiation at doy 147 (nicolaus et al. 2003). approximately 2 days after the commencement of snow thinning the broad-band albedo, as calculated from the sebisup radiation measurements, shows a strong drop from 0.7 to less than 0.4. in 2003, however, the snowcover thickness in the middle of may was 10 cm less than that in 2002, and decreased continuously and slowly, so that 5 cm of snow was still left at the beginning of june. at that time the surface albedo was more than 0.7, still very high compared with 2002 values. during the sebisup 2002 experiment, a sudden change in the properties of the snow cover was observed at the end of may, with the result that the snow was partly melted and partly transformed to superimposed ice at the begining of june. in 2003, the melt conditions were characterized by a snow cover that already started to decay in the middle of may, but then continued degrading very slowly without any abrupt transitions. early in 2003, snow internal temperatures were close to zero, whereas one year before, the melting point was not fig. 3 the normalized difference snow and ice index (ndsii) offset with changing levels of atmospheric water vapour (awv), as taken from atcpro results (�) and the fitted polynomial model (dashed line). fig. 4 time series of the normalized difference snow and ice index (ndsii) for 2002 and 2003, between day of year (doy) 120 (30 april) and 180 (29 june), on fast ice in kongsfjorden. (a) top of the atmosphere (toa) values of ndsii. (b) toa values corrected for atmospheric water vapour (awv). coincident ground measurements were performed in these years. snowmelt detection in kongsfjordens. willmes et al. polar research 28 2009 203–213 © 2009 the authors 207 reached before the end of may. snow wetness was very high from the start of data collection in 2003, and could not be sampled from below a snow height of 0.1 m, as hard superimposed ice layers had already formed below (fig. 6). figure 7 gives an example of how the in situ measured spectral albedo of snow at the sebisup field station changed with approaching summer conditions between doy 141 (21 may) and 152 (1 june) in 2002. the corresponding ndsii value is shown in brackets. the reflectance drop in the near-infrared wavelength region causes an ndsii increase from 0.016 to 0.078 at doy 147 (27 may). the strong rise of corrected satellite-derived ndsii values (fig. 4b) for 2002 also occurs at doy 147. fig. 5 time series of (a) the snow height and (b) the integral surface albedo (automatic weather station data), for the period between day of year (doy) 136 (16 may) and 156 (5 june), measured at the sebisup field station, kongsfjorden, in 2002 and 2003. fig. 6 time series of the mean vertical profiles of (a, b) snow temperature and (c, d) snow wetness, measured at the sebisup field station, kongsfjorden, in 2002 and 2003. snowmelt detection in kongsfjorden s. willmes et al. polar research 28 2009 203–213 © 2009 the authors208 the ndsii values from satellite data turn out to be higher than those from the ground measurements, which results from differences in atmospheric transmission between avhrr channel 1 and 2. unfortunately, spectral albedos could not be measured in 2003 because of an instrument malfunction. ndsii time series from 1990 to 2003 the ndsii between doy 120 (30 april) and 180 (29 june) over fast ice in kongsfjorden shows a strong interannual variability in the period from 1990 to 2003 (fig. 8). each index value represents the spatial average of the fast-ice area in northern kongsfjorden at a specific date (doy). the fact that surface monitoring with avhrr images is limited to clear-sky conditions results in very poor coverage of ndsii values for some years. the fewer clear-sky images that are available, the less structured the ndsii evolution appears. data from 1994 are missing completely because too few useful satellite data could be obtained. ndsii values increased from may to june in all of the years studied. table 2 summarizes the statistics of the calculated ndsii values. the mean spatial variance of the index values within the fast-ice area at a respective date is one order of magnitude lower than temporal variance from may to june. the year 1998 is outstanding, with ndsii values below zero in may, and generally lower values compared with the entire period of 1990– 2003. a negative ndsii value can be caused by dust fig. 7 spectral albedos of snow cover on three different days during the sebisup field campaign in 2002. the numbers in square brackets denote the coincident normalized difference snow and ice index (ndsii) values. fig. 8 time series of the spatially averaged normalized difference snow and ice index (ndsii), measured between day of year (doy) 120 (1 may) and 180 (29 june), from fast ice in kongsfjorden, from 1990 to 2003. the year 1994 is missing because of a lack of clear-sky satellite data. note that the ndsii scale in 1998 differs from the other years because this was the only year with ndsii values below zero. snowmelt detection in kongsfjordens. willmes et al. polar research 28 2009 203–213 © 2009 the authors 209 particles on the surface of the snow from black carbon emissions, which tend to lower the reflection in visible wavelengths, and consequently accelerate the melt process. however, no data on snow impurities were available for kongsfjorden. besides the all-in-all increase from may to june, enhanced index jumps are present in some years. sometimes, the abrupt ndsii increase is only a short positive deviation from the long-term increase (e.g., 1993 and 1995), whereas in most years, sudden increases are follwed by a continuously higher ndsii level (1990, 1991, 1992, 2000 and 2002). ndsii and surface energy balance to assess the suitability of an ndsii time series for the representation of surface conditions, different radiation components from the bsrn station, and meteorological parameters from synoptic observations in ny-ålesund, were compared with the index evolution between may and june. the daily averaged surface energy balance (seb), which is a trigger for the surface melt, is presented in fig. 9. in all of the years studied, at the beginning of may the seb oscillates around zero, and then increases until the end of june. the most pronounced increases occur around doy 150, with the strength and velocity of the increase revealing a high interannual variability. in 2002, the time series of the daily mean seb values between doy 120 and 180 shows the strongest rise after doy 142, and a maximum of approximately 200 w m-2 that was reached around doy 161 (10 june). previously, seb values were generally close to zero, with the exception of values around 40 w m-2 from doy 126 (6 may) to 134 (14 may). in 2003, the seb oscillation around zero was of longer duration, and a less pronounced increase only occurred after doy 150 (30 may). this observation is supported by the ndsii evolution and ground measurements. in 2002, ndsii values increase almost continuously, with an intermediate jump at doy 147, whereas in 2003, the ndsii seems to be nearly constant until doy 148, when a slight increase lifts the index values slowly. consequently, seb and ndsii evolution, as well as in situ data from snow measurements, support each other in reflecting the start of drastic table 2 statistics of the calculated normalized difference snow and ice index (ndsii) values. ndsii statistics value total n 296 mean 0.139 minimum -0.026 maximum 0.47 total standard deviation �0.071 mean spatial standard deviation �0.008 fig. 9 daily mean surface energy balance between day of year (doy) 120 (29 april) and 180 (29 june) for the years from 1993 to 2003, and the 10-day running average (in bold), from baseline surface radiation network (bsrn) data and meteorological tower measurements, in ny-ålesund. snowmelt detection in kongsfjorden s. willmes et al. polar research 28 2009 203–213 © 2009 the authors210 surface changes around doy 147 in 2002, and the much less pronounced surface transition in 2003. interannual variability of melt onset figure 10 summarizes the results of a manual detection of melt-onset periods from the ndsii time series. depending on the availability of clear-sky, near-nadir avhrr images, the melt-onset period is more or less sharply resolved temporally. if more than one date could be considered as melt onset, we always chose the first one. the result shows that melt periods on fast ice in kongsfjorden were undergoing a change towards earlier onset from the beginning to the mid-1990s, whereas the melt periods have tended to occur slightly later since 1997 (fig. 10a). apart from interannual changes in the onset of the melt period, fig. 10 reveals that the significance of the melt signal differs very much from year to year (fig. 10b), such that in 1996, 1999 and 2001 the detected melt signal represents less than 20% of the total ndsii increase in the observational period. figure 10 also reflects the described differences in the ablation periods during the field measurements, with an early/strong melt in 2002 and a late/weak melt in 2003. the ndsii, in combination with the seb time series, reveals years of early melt in 1995, 1996 and 1997, and years of late melt in 2001 and 2003, as well as years of weak melt in 1996 and 1999, and years of strong melt in 1990, 1998, 2000 and 2002. discussion and conclusions this study aimed to evaluate the ndsii index for the long-term monitoring of snowmelt processes in narrow fjords. the ndsii index for the period between 1 may and 30 june was derived for 13 years, from 1990 to 2003, for the fast-ice area in kongsfjorden/svalbard. for the years of 2002 and 2003, field data were available to validate observed changes of the ndsii. the characteristic differences of the melt periods observed in situ in 2002 and 2003 were satisfactorily reflected in the ndsii. the interannual differences in the evolution of the seb in ny-ålesund, at the transition from spring to summer, were also shown to be reflected in the ndsii. snowmelt onset periods were manually identified from the derived ndsii time series. our results show snowmelt varying strongly in strength and date of onset within the observational period. detection of a melt onset date with daily accuracy would require daily coverage of clear-sky, nearnadir images. interannual variations in the absolute ndsii values may partly result from intersatellite calibration differences. moreover, snow bidirectional reflectance variations will have a significant effect on the ndsii values. we tried to mitigate the latter effect by limiting our analysis to near-nadir images. thus, the evolution of ndsii values between doy 120 and 180 presented is likely to represent real changes in surface conditions. variations in the shape of the ndsii time series from may to june can reveal differences in the rate and strength of snow-cover decay (de abreu et al. 2001). the ndsii increase from may to june results from a decrease of the bulk albedo, and the increasing difference between visible and near-infrared albedos of the snow cover. rapid increases of ndsii are likely to represent the latter process. considering that ice break-up might occur as early as june, one must take into account that very high index values at the end of the monitoring period can be biased by subpixel-sized open-water fractions. as stated by de abreu (1996), the formation of melt ponds results in strong ndsii increases. the interpretation of ndsii for the years without coincident field data is difficult, and is limited by the availability of clear-sky data. however, they still offer insight into the strength and rate of snow-cover decay. the correction of satellite data with regards to awv shows that in most cases the corrected ndsii time series turn out to be lower than the uncorrected time series, with more or less the same shape, but with an increasing difference towards the end of the monitoring period. the latter observation is explained by a generally increasing awv content from may to june. the investigation of uncorrected index values may lead to a misinterpretation of abrupt index rises, as is shown for the year 2002, where the recorded date of the enhanced ndsii increase shifted to a few days later after the influence of water vapour was included. fig. 10 melt onset periods for fast ice in kongsfjorden. the black bars in (a) mark the time windows for melt onset, as detected from normalized difference snow and ice index (ndsii) jumps. the grey bars in (b) denote the contribution of the identified ndsii jump to the total ndsii increase between day of year (doy) 130 and 180. snowmelt detection in kongsfjordens. willmes et al. polar research 28 2009 203–213 © 2009 the authors 211 the analysis presented allows for a rough overview on the interannual variations of snowmelt strength and seaice surface decay for fast ice in kongsfjorden. the manual detection of melt onset windows reveals years of early melt and years of late melt, as well as years of weak melt and years of strong melt. follow-on investigations should try to develop a more detailed algorithm for picking melt onset dates from the combined time series of the ndsii, avhrr albedos and surface temperatures. acknowledgements jb was working at the alfred wegener institute for polar and marine research, bremerhaven, germany, when the work presented in this paper was carried out. the authors would like to thank the staff at the sverdrup (norwegian polar institute) and koldewey (alfred wegener institute) stations in ny-ålesund. the helpful comments of two anonymous reviewers are strongly acknowledged. radiometers and meteorological instruments were kindly provided by gert könig-langlo, bernd loose, alfred helbig and uwe baltes. the use of avhrr lac and gac data, through the noaa class, formerly known as the satellite active archive (saa), is greatly acknowledged. the sebisup measurements were performed at the former ny-ålesund large scale facility under eclsf grant np-9/2001 with the support of the alfred wegener institute. this study was partly funded by the german research foundation (dfg) under contract ba 2060/2-2 and ha 2724/4-2 and by the mariclim project funded through nfr (norwegian research council). references anderson m. 1997. determination of a melt-onset date for arctic sea-ice regions using passive-microwave data. annals of glaciology 25, 382–388. belchansky g.i., douglas d.c., mordvintsev i.n. & platonov n.g. 2004. estimating the time of melt onset and freeze onset over arctic sea-ice area using active and passive microwave data. remote sensing of environment 92, 21–39. comiso j.c. 1983. sea ice effective microwave emissivities from satellite passive microwave and infrared observations. journal of geophysical research—oceans 88, 7686–7704. curry j.a., schramn j.l. & ebert e.e. 1995. on the ice albedo climate feedback mechanism. journal of climate 8, 240–247. de abreu r. 1996. in situ and satellite observations of the visible and infrared albedo of sea ice during spring melt. phd thesis, university of waterloo, on, canada. de abreu r., yackel j., barber d. & arkett, m. 2001. operational satellite sensing of arctic first-year sea ice melt. canadian journal of remote sensing 27, 487–501. drobot s.d. & anderson m. 2001. an improved method for determining snowmelt onset dates over arctic seas using scanning multichannel microwave radiometer and special sensor microwave/imager data. journal of geophysical research—atmospheres 106, 24 033–24 049. gerland s., winther j.-g., ørbæk j.b., liston g.e., øritsland n.a., blanco a. & ivanov, b. 1999. physical and optical properties of snow covering arctic tundra on svalbard. hydrological processes 13, 2331–2343. gogineni s.p., moore r.k., grenfell t.c., barber d.g., digby s. & drinkwater m. 1992. the effects of freeze-up and melt processes on microwave signatures. in f.d. carsey (ed.), microwave remote sensing of sea ice. pp. 329–341. washington d.c.: american geophysical union. hill j. & mehl j. 2003. geound radiometrische aufbereitung multiund hyperspektraler daten zur ergänzung langjähriger kalibrierter zeitreihen. (geometric and radiometric processing of multispectral and hyperspectral data to supplement calibrated long time series.) photogrammetrie fernerkundung geoinformation 1, 7–14. holt b. & digby s.a. 1995. processes and imagery of first-year fast sea ice during the melt season. journal of geophysical research—oceans 90, 5045–5062. kawamura t., ohshima k.i., takitzawa t. & ushio s. 1997. physical, structural and isotopic characteristics and growth processes of fast sea ice in lützow-holm bay, antarctica. journal of geophysical research—oceans 102, 3345–3355. launiainen j. & cheng b. 1995. a simple non-iterative algorithm for calculating turbulent bulk fluxes in diabatic conditions over water, snow/ice and ground surface. report series in geophysics 33. helsinki: university of helsinki. nicolaus m. 2006. beobachtung und modellierung der schneeschmelze und aufeisbildung auf arktischem und antarktischem meereis. (monitoring and modelling of snowmelt and superimposed ice formation on arctic and antarctic sea ice.) phd thesis, dept. of geosciences, university of bremen. nicolaus m., haas c. & bareiss j. 2003. observations of superimposed ice formation at melt-onset on fast ice on kongsfjorden, svalbard. physics and chemistry of the earth 28, 1241–1248. perovich d.k. 1996. the optical properties of sea ice. ccrel monograph 96(1). hanover, nh: cold regions research engineering laboratory. perovich d.k., tucker w.b. & ligett k.a. 2002. aerial observations of the evolution of ice surface conditions during summer. journal of geophysical research—oceans 107, 8084, doi: 10.1029/2000jc000449. shivola a. & tiuri m. 1986. snow fork for field determination of the density and wetness profiles of a snow pack. ieee transactions on geoscience and remote sensing 24, 717–721. svendsen h., beszczynska-møller a., hagen j.o., lefauconnier b., tverberg v., gerland s., ørbæk j.b., bischof k., papucci c., zajaczkowski m., azzolini r., bruland o., wiencke c., winther j.-g. & dallmann w. 2002. the physical environment of snowmelt detection in kongsfjorden s. willmes et al. polar research 28 2009 203–213 © 2009 the authors212 kongsfjorden–krossfjorden, an arctic fjord system in svalbard. polar research 21, 133–166. winther j.-g., edvardsen k., gerland s. & hamre b. 2004. surface reflectance of sea ice and under-ice irradiance in kongsfjorden, svalbard. polar research 23, 115– 118. zhang t., scambos t., haran t., hinzman l.d., barry r.g. & kane d.l. 2003. ground-based and satellite-derived measurements of surface albedo on the north slope of alaska. journal of hydrometeorology 4, 77–91. snowmelt detection in kongsfjordens. willmes et al. polar research 28 2009 203–213 © 2009 the authors 213 light and productivity of phytoplankton in polar marine ecosystems: a physiological view egll sakshaug and dag slagstad sakshaug. e. & slagstad. d . 1991: light and productivity of phytoplankton in polar marine ecosystems: a physiological view. pp. 6s-85 i n sakshaug. e.. hopkins. c. c. e. & britsland. n . a . (eds.): proceedings of the pro mare symposium on polar marine ecology. trondheim. 12-16 may 1990. folur research 10(1). this study deals with the modelling of photosynthesis and growth of polar phytoplankton and variations in relevant parameters. polar rcgions are chardctcriscd by low sun elevations (< 4k50"). extreme seasonal variations in irradiance and day length. and low sea temperatures ( i . r to 6°c). due to the latter. maximum phytoplankton growth rates are low (< 0 . 6 d ' ) . light absorption by phytoplankton is strongly dependent o n spectral composition (blue oceanic versus green coastal waters), but absorption characteristics (and thus chlorophyll a-normalised photosynthetic efficiency $) d o not differ appreciably between polar and othcr phytoplankton. the maximum chlorophyll normalised photosynthetic rate p t is, however. lower and dependent on the irradiance to which the cells are adapted. chla:c ratios vary widely. but within ranges known for other phytoplankton. the carbon normalised coefficient p', varies little with irradiance. but is clearly dependent on day length and nutrient supply. the corresponding coefficient a' is somcwhat higher in shade-adaptcd than in light-adapted cells. polar species exhibit a high tolerance for strong light and long days in combination with low temperature relative to other species. the interpretation of p-l functions is discussed, and an empirical formulation is suggested that does not need the chla:c ratio for predicting the light-limited gross growth rate of polar phytoplankton. math ematical simulations of the spring bloom indicate that the depth of the mixed layer and the attenuation of light are the most important variables for determining the photosynthetic rate. the spectral composition of light is of particular importance in low light, e.g. in deeply mixed layers. generally, the deeper the mixing, the more sensitive thc development of a spring bloom becomes to any algal or environmental variable. egil sakshaug, trondhjem biological station. the museum, unioersily of trondheim, bynesoeieri 46. n 7018 trondheim. norway; dag slagstad. sintef. auromaric conrrol. n-7034 trondheim-nth. norway. 'j*p,~,4~\ns" introduction polar marine environments are characterised by extreme variations in irradiance and day length, and temperature is generally low (1.8 to 6°c). the arctic seas, including the bering, greenland and norwegian seas, reach as far south as 60"n, and the antarctic ocean, defined as extending north to the oceanic polar front, reaches latitudes as low as 45-50"s. photosynthetic and growth rates of phyto plankton in polar seas may vary significantly because of variations in the light regime, but they are generally low d u e t o low temperature. phytoplankton is continuously exposed t o a light gradient because of variations in atmospheric light and mixing in the water column. because light is attenuated in water, the depth of the mixed layer and the rate of mixing are essential in controlling the radiation available t o algae: the deeper the mixing, the less light on the average is available to the phytoplankton community. in polar areas, blooms may be triggered by the melting of sea ice which leaves phytoplankton suddenly exposed t o strong light; a brackish layer which is formed a t the same time restricts the depth of mixing. t h e melting of sea ice thus gives rise t o a bloom which trails the receding ice edge and thus occurs later at higher latitudes. this scenario was suggested by gran (1931). although such blooms have been observed in all polar seas covered by sea ice [see sakshaug (1989) for review], they are not easily identified when the ice edge is poorly defined and when ice drifts across nutrient-depleted waters late in the growth season. the relationship between vertical mixing and the growth of phytoplankton was first proposed by alexander nathansohn in 1906 (quoted in braarud 1935). the relationship was demon strated by braarud & klem (1931) through com parison of the early blooms in the shallowly mixed romsdalsfjord in western norway with the late blooms in the norwegian sea (may-june), and by riley (1942; 1946) at st. georges bank. o n 70 egil sakshaug & dug slagstad the basis of such observations, sverdrup (1953) developed a mathematical model in which he introduced the concept of critical depth (zcr). which is defined as the depth above which depth-integrated photosynthesis equals depth integrated respiration: a bloom develops when vertical mixing is less deep then the critical depth (i.e. the integrated photosynthesis exceeds the integrated respiration). the critical depth may approximately be defined as z,, = ps/kr (1) where ps is biomass-specific photosynthetic rate at the surface, k is the vertical attenuation coef ficient of light in seawater and r is the biomass specific respiration rate of algae. it follows that z,, becomes large when ps is high or k and r are low. sverdrup calibrated his model against data from the weather ship m in the norwegian sea and derived a critical depth that ranged from 30 40 m in march to 230-280 m in may. sverdrup's model is the backbone of many mathematical models for primary production and may be fairly realistic for predicting the onset of spring blooms. improvements can be made by including a non-linear relationship between pho tosynthetic rate and irradiance. the effect of the variable spectral composition of light, and self shading by phytoplankton. moreover, although sverdrup was aware of the importance of losses through, for example, grazing and sedimentation, the model included only the algal dark respiration rate. unless terms for grazing and sedimentation are included, predicted critical depths may be hundreds of metres i n clear waters far deeper than depths of mixing above which phytoplankton blooms actually occur (4&80m, sakshaug & holm-hansen 1984; bodungen et al. 1986; sme tacek & passow 1990). finally, algae can adapt to changes in the environment, usually in a fashion that minimises the impact of environmental vari ation on photosynthetic and growth rates (sak shaug & holm-hansen 1986). adaptation changes the values of algal parameters, some of which are essential i n dynamical phytoplankton models, e.g. p-i coefficients and the chlorophyll a : carbon ratio. the present paper deals with light absorption by polar phytoplankton, mathematical models of photosynthetic and growth rates as well as photo adaptation of polar phytoplankton. the model is examined by analysing recent data from the barents sea and comparing observations of spring blooms with predictions. polar primary pro duction has been reviewed elsewhere (platt & subba rao 1975; horner 1976; alexander 1980; nemoto & harrison 1981; subba rao & platt 1984) as has the physiological ecology of polar phytoplankton (jacques 1983; sakshaug & holm hansen 1984; sakshaug 1989; smith & sakshaug 1990). the photosynthetically relevant aspects of marine optics have been reviewed recently (see morel 1988; sathyendranath & platt 1989 and references therein; see also jerlov & steemann nielsen 1974; jerlov 1976; tyler 1977; kirk 1985 for general introduction). atmospheric light in polar areas sun elevations are generally low in polar areas. the highest elevation (noon, summer solstice) at 80" latitude is 33.5" and at 60" latitude 53.5". on the other hand, at latitudes >66.5", the sun does not set for part of the summer. because of this, daily incident irradiance on a cloudless day in midsummer may in fact be higher at high latitudes than in equatorial areas (campbell & aarup 1989). the diurnal trajectory of the sun is given by i 1 i i a b c q 4 8 12 16 20 24h fig. i . diurnal solar trajectory as a function of latitude. the position of the horizon depends on season: a = at summer solstice. b = at equinox, and c = at winter solstice. a and c are 47" apart. light and productivity of phytoplankton 71 latitude only and becomes “flatter” the higher the latitude (see kirk (1985) for astronomical equations), whereas the horizon may be thought of as moving up or down relative to this trajectory according to the seasons (fig. 1). the math ematical model by bird (1984), which predicts spectral scalar irradiance for cloudless days at the sea surface as a function of sun elevation, implies that relative spectral distribution of atmospheric visible light varies little between solar elevations >lo” (fig. 2). predictions from this model also correspond well with data from the barents sea in that the highest measured scalar irradiances (par, i.e. photosynthetically active radiation, integrated over 400-700nm) at sea surface approximate but d o not exceed model predictions (fig. 3). generally, cloud conditions and the wind rep resent major problems in the modelling of ocean and atmosphere dynamics and thus plankton dynamics. the subarctic region and the mid-to northern part of the antarctic ocean are, however, in the atmospheric “low pressure belt” in which atmospheric low pressures move incess antly eastwards. this usually yields a weather cycle characterised by 4-6 cloudy and windy days followed by 1-3 more or less sunny days and less windy days. this induces rhythm in incident light and vertical mixing and is thus of relevance for primary production (sakshaug et al. 1991b). because atmospheric low pressures tend to follow the same trajectory for several weeks, cycles of cloudiness and wind may to some extent be repro ducible properties of this belt. at high latitudes, in the polar high pressure zone, sunny days may be more frequent but, particularly in the high arctic, where weather may be calm for extended periods, a thin layer of fog may frequently be formed. *a 0 i i i 0 4 8 12 16 2‘0 2 i h fig. 3. scalar irradiance (par) at the sea surface on 100% cloudy days (solid circles) and partly cloudy days (open circles) in the period 25 may-6 june, 1987, at 74”n in the barents sea. data provided by g . b . mitchell. the curve represents predictions for a cloudless day (bird 1984). cloud cover and fog may reduce incident light by up to 70-80% (kirk 1985). in the southern half of the barents sea, the average scalar irradiance (par) on fully cloudy summer days is on average only 18 ? 6% of the irradiance predicted for a clear day, whereas sunny/partly cloudy days aver age 55 * 20% (fig. 2). according to the same set of data, 28 of 46 summer days were fully cloudy, and scalar irradiance (par) at 2 m depth was nm fig. 2. spectral distribution of incident light (scalar irradiance, relative scale) at the sea surface on a clear day as a function of sun elevation (after bird 1984). 72 egil sakshaug & dug slagstad 41 2 5% of scalar irradiance ( p a r ) at the surface. o j 50 attenuation of light by clear water and sea ice in clear oceanic waters. blue rays penetrate the deepest. for "clearest" ocean water (smith & baker 1981). the minimum vertical attenuation coefficient is 0.0168 m ' at 450 nm wavelength. while u v ( 2 0 0 n m ) and infrared radiation (760nm) have coefficients as high as 3.14 and 2.55 m-i. respectively. next t o blue, ocean water is most transparent t o violet and green (fig. 4). a b ,.. e a 2 b 5 10 50 100 300 o . 0 1 4 , ~ ~ . , i , , . , j 2 0 0 300 400 5 0 0 6 0 0 7 0 0 nm hg. 4 . vcrtical diffusc attenuation cocfficicnt of light and 1 5 light depth in ( a ) "clcarcst" ( b l u c ) ocean watcr (smith & baker 1981) and (b) "clcarcst" grccn watcr in tmndhcimsfjordcn. norway. early march ( g c i r johnscn. unpuhl d a t a ) . fig. i. vcrticdl diffusc attenuation coefficient ( p a r ) in ( a ) "clcarcat" ocean u a t c r and (6) "clcarcs~" trondhcimsflordcn u a t c r samc data a s in fig. 4. e c a 0 whereas deep-sea polar waters in winter. par ticularly in the antarctic o c e a n , may be fairly similar t o this "clearest" water (gieskes e t al. 1987). waters o n shelves and in bays and fjords in northern areas may have minimum attenuation coefficients in the green part of the spectrum (500-600 nm). norwegian fjord and coastal cur rent waters a r e , for instance. characterised by input of dissolved yellow matter, mainly of baltic origin, and therefore strongly absorb blue and violet radiation (fig. 4). these waters generally have a much higher attenuation coefficient in terms of p a r than the "clearest" blue ocean water (fig. 4). because phytoplankton a r e highly discriminatory with respect t o absorption of blue and green light, shifting the spectral distribution of light in water towards green as a bloom devel ops, the spectral characteristics of seawater are ecologically important (fig. 5 ) . light is greatly attenuated by ice a n d , in par ticular. snow. palmisano e t al. (1986) have reported diffuse vertical attenuation coefficients ( p a r ) of 16-45 m ' for snow, i.e. a 5 0 c m thick layer will only transmit 0.01-3% of incident light. sea ice has coefficients of 1.5-1.611-l ( p a r ) (maykut & grenfell 1975). i.e. a 1 m thick layer of sea ice will let through about 20% of incident light. consequently, ice and its snow cover reduce incident light so much that there is hardly enough for more than algal subsistence below the under side of sea ice. absorption of light by particles the absorption of light by phytoplankton depends on species size/morphology as well as pigment light and productivity of phytoplankton 73 between shadeand light-adapted cells may also be caused by changes in pigment composition (fig. 4). the "package" effect is pronounced in a barents sea clone of the large-celled centric dia tom thalassiosira nordenskioeldii (fig. 6); e.g. "ac for red light (676 nm) is 0.016 m2 (mg chla)-] for cells growing at 400 pmol m-z s ] and 0.0073 for cells growing at 25 pmol m-z s-i. natural populations in the barents sea exhibit the same trend, e.g. "a,(676) averages 0.011 in the well-lit upper 10 metres and 0.0057 mz (mg chla)-' below 60 m depth (table 1). 'ac may overestimate absorption of photo synthetically usable light by algae because some of the absorbed light is unavailable for photo synthesis. this pertains, for instance, to light absorbed by photoprotective pigments such as diadinoand diatoxanthin which do not transfer energy to photosystem i1 (vernet et al. 1989). chla-normalised absorption of photosynthetically usable light (pur) may rather be approximated by properly scaled fluorescence excitation spectra (of), which mimic well the shape of action spectra for oxygen evolution in photosystem i1 (neori et al. 1988). scaling of relative spectra has until recently been a problem, but can now be easily carried out by use of the dye basic blue 3 for quantum correction and matching of the peak at 676nm of the corrected spectrum to the cor composition, but it is presumably relatively inde pendent of temperature and thus not in principle different for polar and other species (mitchell & kiefer 1988). the predominant algal species in polar regions have in vivo light absorption spectra which pri marily reveal the absorption characteristics of chlorophyll a (fig. 6): one major absorption peak at 440nm, i.e. not far from the wavelength of minimum attenuation in blue water, and one at 675 nm (red), which is of less ecological relevance since seawater attenuates red light efficiently in the upper few metres. spectra of the more impor tant groupsof polar algae. e.g. diatomsand phaeo cystis pouchetii, exhibit in addition a shoulder caused by fucoxanthin and closely related com pounds at about 500 nm, and minor peaks due to chlorophyll c at 590 and 630 nm (fig. 6). chlorophyll a-specific absorption of light ("a,) by phytoplankton cultures ranges from 0.0043 0.034 at 676nm and 0.004-0.09m2 (mg chla)-' at 440 nm (maske & haardt 1987). self-shading in and between chloroplasts may lead to low chla normalised absorption by chla-rich (shade adapted) cells. this is particularly pronounced in large cells with many chloroplasts (the "package" effect; kirk 1975; bricaud et al. 1983; mitchell & kiefer 1988; berner et al. 1989). large differ ences, however, in the absorption of blue light fig. 6. in vivo chlo-specific light absorption spectra for the large centric diatom tho/afsiosira nordenskioeldii (earents sea clone) grown at 0.5"c and at 400 (tn-hl) and 25 pmol m 2 s ' (tn-ll). "ac: total absorption. o f : chlorophyll o-fluorescence excitation spectrum (emission 730 nm) scaled to "ac at 676 nm (sakshaug et al. 1991a). e" n e 0.04 0.03 0.02 0.0 1 500 600 500 600 nm 74 egil sakshaug & dug slagstad responding peak of 'ac (kopf & heinze 1984; maske & haardt 1987; sakshaug et al. 1991a). for thalassiosira nordenskioeldii, "f is 42 and 86% of 'ac of lightand shade-adapted cells, respectively, at 440 nm. hence, of varies less than 'ac with photoadaptational status in this species, although it is nevertheless lower for shade adapted than for light-adapted cells (fig. 6). the large difference in terms of oac between lightand shade-adapted cells in the blue region is pre sumably i n part due to the much higher content om i ; of diadinoand diatoxanthin in the former (sak shaug et al. 1991a) and therefore does not rep resent a simple "package" effect. the absorption of light by all particles in the 500 700 500 700 nm seawater (*a,) can be much larger than 'ac. par ticularly when the supply of terrigenous material is large (e.g. feeding by glacial rivers), and fre quently considerably larger also in offshore areas (morrow et al. 1989). in the barents sea. the difference between *ac and 'ac is small in the early phase of ice-edge blooms, but becomes larger i n the late phase, particularly near the surface (fig. 7). the difference between *a, and 'ac in waters with little terrigenous material appears to be caused primarily by pigments which are creamish yellow and insoluble in methanol. kiefer et al. (1990) have suggested that these pigments are in the main cytochromes, i.e. respiratory enzymes fig. 7. examples of chlo-specific absorption of light by particles in the barents sea (0 and 10 m depth, 2 june 1987). 'a, = total absorption by particles. = in vivo absorption by chloroplast (methanol-soluble) pigments and their derivatives ( e . sakshaug. unpubl. data). present in procaryotes as well as eucaryotes. this raises the possibility that the difference between *ac and 'ac may be used to estimate respiratory activity in seawater. when phytoplankton stocks are low (e.g. oligotrophic situations), absorption of light by heterotrophs and other non-algal par ticles may be larger than absorption by chloroplast pigments (smith et al. 1989). table 1 . averaged photosynthetic parameters (24 and 12 h day length) for thalassiosira nordenskioeldii and chaetoceros furcellarur grown at 0.5"c and natural populations in the barents sea (may-june 1987. 5-25 data sets for each depth range). "f is the integrated value ( w 7 0 0 n m ) of "f taking the spectral distribution of the illumination into account (calculated in analogy with equation 6 ) . culture data from sakshaug et al. (1991a); field data provided by f . r e y . e . sakshaug. m. vernet and b . g. mitchell. for explanation of symbols, see text. cultures ~ barents sea pmol m j s ' rn 0 025 1 7 0 024 0 011 0 058 0 045 68 405 depth. m 25 0-20 3 m >70 0.023 0.026 0.025 0.020 0.8 1.6 1.3 0.9 0.014 0 011 0.0094 0 0057 0.0078 0.070 0.035 35 63 52 46 1080 ' rng c (mg chla).' h ' ( y m o l m 2 s ' ) ' ' umol m ? s-i ' rn' (mg chlo).' rng chla (mol p s u ) ' g-at c (mol).' mg c (rng chla).' h ' ' growth-normalised values light and productivity of phytoplankton 75 in equation 4, the system of units conveniently differs from that of equation 3: pb is in g-at c (mg chla)-' h-l and e, in mol m-2 h i . ouis the chla normalised specific absorption of photosynthet ically usable light [m2 (mg chla)-']; the scaled fluorescence excitation spectrum o f may be used as an adequate approximation (sakshaug et al. 1991a). t is the minimum turnover time for elec trons in the photosystems (h), and q is the amount of chla per photosynthetic unit [mg chla (mol psu)-'1. the psu is here functionally defined, e.g. the existence of different photosystems is disregarded q t probably mainly represents properties of psii. $,,,, the maximum quantum yield, converts photons to carbon [g-at c (mol photons)-'] or oxygen [mol o2 (mol photons)-']. equation 4 is the product of a linear function for photosynthesis versus irradiance multiplied by the poisson probability (pp) for a photon to hit a photosynthetic unit with an open reaction centre (i.e. the quantum efficiency). the latter term has the value 1 for zero light and the value zero for infinite irradiance: p b = ($max ode, ) (linear) x [l e ~ p ( ~ u q t e , ) ] / ~ u q t e , . (5) (pp) when multiplied by $,,,, the poisson probability term predicts the quantum yield. equations 3 and 4 are mathematically equiv alent, thus 9 = 43.2 $,,,"a. p: = 12000 p:/qt, and ik = 278/"uqt. it should be noted that p: and p-i functions p-i functions describe the photosynthetic response of phytoplankton to irradiance. the sim plest formulation is a straight line: p = lye, (2) where p is biomass-normalised carbon uptake (or oxygen evolution), e, is irradiance, and ly is the slope of the line. this linear relationship was used in sverdrup's (1953) model. because, however, the quantum yield of photosynthesis decreases with increasing irradiance, the photosynthetic rate in reality forms a saturation function with irradiance. equation 2 is therefore adequate only at very low irradiances. an empirical and simple saturation function (fig. 8) was suggested by webb et al. (1974): pb = p i [ l exp(-mbe,/p:)] (3) where pb is chlorophyll-normalised carbon uptake [mg c (mg chla)-l h-'1, p i is maximum carbon uptake, e, is in pmol m-2 s k i , and 9 is the slope of the curve at the origin [mg c (mg chla)-' h-' e i l ] . the ratio p:/@, the light satu ration index, is termed ik. an alternative formulation for equation 3 based on target theory (arnold 1932; myers & graham 1971; ley & mauzerall 1982; dubinsky et al. 1986) has been suggested by sakshaug et al. (1991a). this formulation makes the physio logically relevant coefficients explicit (fig. 8): pb = ($max/qm e x p ( " ~ q ~ e , ) l . (4) fig. 8. p-i curve according to webb et al. (1974) and target theory notation (sakshaug et al. 1991a). because of "u, values for ab and ik depend on the spectral distribution of the light. 76 egil sakskaicg & d a g slagstad e 1 as include the conversion factor whereas ik does not and that p z is spectrally independent in accordance with experimental data (rochet et al. 1986). because c@ and i k include the spectrum ' a , they depend on the spectral distribution of ambient light. if ou (e.g. of) and c@ for the p-i incubator light source is known, the integrated value ab (400-700 nm) for a particular submarine light regime can be calculated if the spectral dis tribution of that light is known (morel 1978; lewis et al. 1985: soohoo e t al. 1987): mb = 43.2 $,,, " u = 43.2 7110nm [i,,,,, " d n ) e , . d ; l l / e , , ( p a r ) l . (6) eja) is the spectral irradiance of the particular light regime and e j p a r ) the integrated (40c 700nm) irradiance for the p-i incubator. equation 6 implies that mb derived on the basis of a "white" i n g b a t o r light source may differ from the value ab relevant in the field (fig. 8). a s s u m b an infinitesimally small phytoplankton stock. a" may increase with depth by a factor > 2 in blue oceanic waters because the water becomes "bluer" (fig. 9 ) . in green waters the converse takes place. when phytoplankton bloom. blue radiation is more rapidly absorbed by algae. so that blue waterwith 10-15 mg chla m--'resembles green water optically. this has the additional implication that. unless special correction algor 20 fig. 9. variations in the integrated (4w700 nm) value d as a function of changes in spectral distribution of light wlth depth (infinitesimal chlorophyll concentration assumed for a and b ) : a = "clearest" ocean water (fig. 4): b = "clearest" trondhcimsfjordcn water (fig. 4 ) : c = "white" halogen lamp (osram h 0 1 250); d = "clearest" blue water with 10 mg chla m-': e = "clearest" blue water with 15 mg chlo m-'. tthms are employed, satellite images of chloro phyll in the sea may considerably overestimate phytoplankton stocks in humus-laden waters, such as along the norwegian coast. variations in p-i coefficients p-i coefficients a r e adaptive parameters. i.e. their values may change as a response to the environ ment in which the algae have been growing. t h e rate of adaptation depends o n the coefficient in question, but data are sparse and d o not form a general pattern (gallegos e t al. 1983; post et al. 1984: sakshaug et al. 1987; cullen & lewis 1988; hegseth 1989). changes in the chla:c ratio may be completed in a matter of a few hours to some days. p-i coefficients may change in the course of <30 minutes (lewis & smith 1983; legendre et al. 1988); therefore. functions o t h e r than 3 and 4 may correspond better with t h e data if incubation time is longer than this (jassby & platt 1976; platt et al. 1980; leverenz 1988). day length and nutrient supply apparently affect chla-normalised p-i coefficients little compared t o irradiance, although this may b e species-dependent (sak shaug et al. 1989: 1991a). ab. p i and ik of polar phytoplankton exhibit a bewildering variability (see harrison & platt 1980: 1986; smith & sakshaug 1990 and ref erences therein). reported values for $ in white light range from 0.001-1 mg c (mg c h l a ) ' h ' light and productivity of phytoplanktorl 77 sumably related to a low value for "f i n shade adapted algae. moreover, data sets from northern areas exhibit a clear positive covariation between $ and p i (harrison & platt 1980; 1986). a physiological reason for this covariation may be the concomitant lowering and raising of of and the product qt, respectively, when light-adapted cells become shade-adapted (table 1). variability in @,,, will also cause p i and a" to covary. and "f put constraints on the variation i n 9. for white light, of is hardly higher than 0.004 0.015 m2 (chla)-i (sakshaug et al. 1991a). this value and the theoretical maximum of 0.125 for $,,, imply an upper limit of 0.08mg c (mg chla)-' h-' (pmol m-z s-')-' for ab. for total carbon uptake, l@ is likely to be lower than 0.05, whereas $ for filtered samples (the majority of published data) may be as low as 0.0254.040. assuming a minimum value for "f of 0.004 m2 (mg chla)-l. the lower limit for ab (filtered samples) becomes 0.007. the large majority of reported values for $ of polar phytoplankton are actually between 0.007 and 0.040. the chla:c ratio varies inversely with irradiance and day length and proportionally with nutrient supply (sakshaug & andresen 1986). therefore the patterns of variation for the carbon normalised p-i coefficients p: and & (i.e. p: and ab, respectively, multiplied by the chla:c ratio) differ from those of p i and ab. in fact, p:, the maximum hourly carbon turnover rate, appears to be relatively independent of irradiance (sakshaug & holm-hansen 1986) but strongly dependent on day length (table 2) and nutrient status (sakshaug et al. 1989). & appears to increase somewhat when cells become adapted to low irradiance and short days, largely because "f decreases less than the chla:c ratio increases (sakshaug & holm-hansen 1986; sakshaug 1989). thus shade-adapted cells are photo synthetically more efficient than light-adapted cells, in spite of the opposite impression given by variations in $. (pmol m-l s-l)-] and for p i from 0.1-15 mg c (mg chla)-'. the majority of values for l@, how ever, range from 0.010-0.030 and for p i from 0.3-2.0. also ik exhibits a pronounced variability: 0.5-700 pmol m-2 s-i has been reported, although the majority of values lie between 30 and 200 pmol m-2 s-i. some values, particularly the extreme ones, may be erroneous due to prob lems in measuring carbon uptake and chla and extensive manipulation of the samples before incubation (including shocks caused by strong light, and in the special case of ice algae: caused by melting). data sets may be difficult to compare because of differences i n methodology: incubation time and time of day may be significant (smith & lewis 1983; legendre et al. 1988), the spectral composition of incubator lamps may differ, and whereas some data sets are based on filtration of samples after incubation, others are not. finally, species composition of communities may play a role. adaptive variation in natural communities may therefore be difficult to distinguish from vari ations caused by other sources. @,,,, which is included i n both p! and ab, cannot be measured directly and is therefore a residual in regressions. it thus "absorbs" sys tematical errors, and, more important, it depends on how much of the flow of fixed energy through the cells is intercepted by the method for meas uring photosynthesis. measurement of oxygen release which takes place in photosystem i1 and therefore before any fixed energy is spent by dark reactions may yield values close to the theoretical maximum [0.125 mol o 2 (mol photons)-']; carbon uptake does not, because a fraction of the supplied energy is spent on uptake of nutrients instead of the uptake of carbon. typi cal values for carbon uptake (unfiltered samples) are 0.07-0.08 g-at c (mol photons)-' (langdon 1988). moreover, estimates of carbon uptake based on filtered samples ( e . g . growth-relevant estimates) yield values as low as 0.04-0.06 g-at c (mol photons)-', i n part because they do not include production of extracellular carbon (zie mann et al. 1987; sakshaug et al. 1991a). some low values for @,,,ax have been reported because they have been calculated as $pac instead of l@/"f. for light-adapted cells the difference can be considerable (e.g. = 50%). $ of arctic phytoplankton may be equal or somewhat lower for shade-adapted than for light adapted algae (platt et al. 1982); this is pre light-limited growth rates reported growth rates of polar phytoplankton are up to 1.7d-' [see smith & sakshaug (1990) for review]; long-term studies (several days) of shipboard cultures, however, indicate maximum rates of 0.35-0.90d-' at <5"c (sakshaug & holm-hansen 1986; wilson et al. 1986; spies 78 egil sakshaug & dag slagstad 1987). the maximum growth rate among cultures of 10 diatoms from the barents sea grown at -0.5"c was 0.64 d ' ? and the average maximum for the ten species was 0.52 d ' (gilstad & sak shaug 1990). the function by eppley (1972), which predicts the maximum ternperature-depen dent growth rate among numerous temperate species grown in laboratory cultures at >2"c, predicts by extrapolation a maximum growth rate of 0.55d-' at 0°c. it thus seems that maximum growth rates of polar phytoplankton on the aver age are not higher than those that would be exhibited by temperate species at low tempera tures. experiments with shipboard cultures of natural communities (sakshaug & holm-hansen 1986: sakshaug 1989) indicate an optimum range of 35 105 pmol m-2 s i for antarctic ice-edge com munities, yielding a growth rate of 0.25 d ' , and 100-250 pmol m-? s ] for a barents sea plankton community. yielding a growth rate of 0.46d-' (syvertsen, holm-hansen and sakshaug quoted in sakshaug 1989). gilstad & sakshaug (1990) reported a wider optimum range (70 to 330 500 pmol m-ls-') for cultures of barents sea dia toms and a strong dependence of growth rate on day length. the growth rate is a function of the difference between gross particulate production rate and cellular loss rates (respiration, extracellular pro duction). it is thus a function of rates which themselves are composite functions of environ mental variables. the q l o value of polar phyto plankton for dark respiration (i.e. the factorial increase due to a temperature increase of 10°c) is apparently higher ( 2 . 3 1 2 ) than that for gross photosynthesis (1.4-2.2; neori & holm-hansen 1982; tilzer & dubinsky 1987). thus a small temperature change may affect the growth rate considerably by altering the respiration rate. res piration rates also tend to increase adaptively with increasing irradiance (falkowski & owens 1980; langdon 1988; sakshaug et al. 1991a) and may be higher during light hours than dark hours (weger et al. 1989). the steady-state gross growth rate p + r (d-') of phytoplankton, where r is the daily carbon specific respiration rate (and in principle includes extracellular production), may be modelled (ban nister & laws 1980; sakshaug et al. 1989; cullen 1990) : p + r = (chla:c). d . gpb = g p c . d (7) in this empirical formulation, g p b may represent equations 3 or 4 with growth-normalised coef ficient values, and the ch1a:c ratio, accordingly, is in either mg mg-i or mg ( g a t ) ' , and d is day length (h). because growth-relevant carbon represents a fraction of the total fixed carbon, whereas the growth rate is an integrated feature over 24 h and p-i coefficients may vary somewhat diurnally, gpb may differ from pb of p-i curves. sakshaug et al. (1991a) have suggested that @,,, in equation 4 may be adjusted to a growth-rel evant value the other coefficients being retained. for equation 3 this implies a pro rata adjustment of 2 and pe to growth-relevant val ues bcy and g p i , respectively, whereas ik is retained: p + r = (chla:c) . d . (g@max/qt) x [l exp(-"uqte,)] toble2. ch1o:c ratio (mg m g ' ) and the product p:(chlo:c). h ' ( = p $ ) for cultures and natural populations in the barents sea. the upper mixed layer. when thin. may have chlo:c ratios <o.ol. whereas the chla:c ratio of the chlorophyll maximum layer, which is a few metres thick and is situated between 25 and 65 rn depth. may have ratios >0.025. same data set as in table 1 . culrures: day length 24 12 prnol m ' sk' 400 25 400 25 chla:c pc, 0.013 0.025 0 043 0.031 0 033 0 047 0.049 0.037 barenrs sea: depth. m 0-20 p', 0.021 chla:c 0.013 30-60 >70 0 021 0.031 0.027 0.028 light and productivity of phytoplankton 79 for some barents sea diatoms (table l ) , g&,,ax is on the average 0.04g-at c (mol photons)-]. equation 8 and its counterpart based on equation 3 may also be written in terms of carbon-nor malised coefficients; then the changed coefficients (q and 'u or $ and p z , respectively) will necess arily include the variations of the ch1a:c ratio. such equations would be mathematically equiv alent to equation 7 of kiefer & cullen (1991 this volume). at very high latitudes, where a light on/ light off cycle may be hard to define, precision may be improved by replacing the product d . gpc with summation of hourly estimates for gpc. in conjunction with an earlier version of this model (sakshaug et al. 1989), it was suggested that irradiance-dependent variation in photo synthetic coefficients might be neglected with little loss of precision. data for arctic diatoms (table l ) , however, suggest that irradiance dependent variations in "f and the product q t should not be entirely neglected. variability in of, and thus @', strongly affects predictions of carbon uptake for low light, whereas variability in q t , and thus gp:, affects predictions for high light strongly. the use of properly chosen con stants, however, is certainly more convenient than the use of variables and should be adequate for most practical purposes. because of practical difficulties in measuring the ch1a:c ratio in the field, other equations than equation 8 may be more convenient. substitution of the chla concentration for the ch1a:c ratio may yield gross daily particulate production of carbon instead of gross growth rate (cullen 1990). empirical functions without the chla:c ratio may also be developed, albeit at a price of less gener ality. because p$ varies less with irradiance than p: and the chla:c ratio individually (table 2) and the growth rate of diatoms appears to be related to day length by half saturation kinetics (gilstad & sakshaug 1990), the gross growth rate may be modelled: f + r = (p + r ) m a x id/(kd + d)i x [ i exp(-eo/ik.)i (9) where (p + r)max is the asymptotic maximum gross growth rate (d-l), and kd is the half saturation constant for day length (d, h). for the ten barents sea diatom species studied by gilstad & sakshaug (1990), (p + r)max was 0.75 d-' (r assumed to be 0.05d-l), k,, 12.4h and ik 2 0 p m 0 l r n ~ s ' ("white light"; fig. 10). this set of coefficients is 0.4 73 1 0 j 0.2 0.4 predicted d ' fig. 10. predicted (equation 8) versus observed average gross growth rates for 10 barents sea diatoms grown at different irradiances (3-5-500~mol m-* s i ) and day lengths (4-24 h) and -0.5"c. standard deviation: 0.035 d ' . based o n data from gilstad & sakshaug (1990). valid only for nutrient-saturated cells at -0.5"c (no photoinhibition assumed), and may serve as a useful guideline for light-limited gross growth rates of phytoplankton in polar waters. photoinhibition photoinhibition may be defined as a lowered pho tosynthetic or growth rate when light becomes strong. on the basis of equation 8, it is evident that photoinhibition of growth can be mediated through an increase in the respiration rate, a decrease in the chla:c ratio, a change in the photosynthetic coefficients of a combination of these. strong light does inhibit growth of polar phyto plankton. in a culture of antarctic pennate ice edge diatoms, the growth rate dropped from 0.25 to 0.19 d-l for an increase in irradiance from 104 to 990 pmol m-2 s-i (sakshaug & holm-hansen 1986). the growth rate of a culture of thal assiosira bioculata from the barents sea dropped from 0.47 to 0.36 d-' for an increase from 230 to 430 pmol m-2 s-l (sakshaug 1989). the chla:c ratio, however, dropped relatively more: from 80 egil sakshaiig & dug slagstand 0.010 down to 0.0040 and from 0.021 down to 0.013 mg mg-i. respectively. this implies that inhibition of growth has been mediated by a decrease in the chla:c ratio and that epb (and thus gp$) may. in contrast. have increased. photoinhibition in terms of chla-normalised photosynthetic coefficients appears to be likely only during short-term exposure to strong light. e.g. before the cellular concentration of photo protective pigments has had time to build u p (lewis & smith 1983) or if the ability to build u p high concentrations is lacking, which is highly species-dependent (sakshaug et al. 1987). inhi bition may occur when populations in vertically mixed waters are briefly exposed to the illumi. nation near the surface, and shade-adapted popu lations appear to be more susceptible than light adapted populations (platt et al. 1982). short-term photoinhibition is usually described by the empirical p-i formulation of platt et al. ( 1980). pb = p![l exp(-abeo/p:)l x exp(-pbe,/p:). (10) pp represents the potential maximum carbon uptake (same units as p:) and bb is a photo inhibition coefficient (same units as g ) . for pb = 0. this function is equal to equation 3. is highly variable in polar phytoplankton: reported values range from about zero t o 0.021 [see smith & sakshaug (1990). for review]. t h e majority of values however. are <0.0003. this implies a reduction in pa of < 2 4 % relative to p," at 1000 pnol m ? s-l. because irradiance ( p a r ) at 0.5 m depth is not higher than 1000-1500 pmol m-'s-i at 63 74" latitude and the weather is frequently cloudy (hegseth & sakshaug 1983; b . g. mitchell, unpubl. data), photoinhibition of the growth rate as well as of the short-term photosynthetic response should be of little significance in polar regions and certainly in terms of depth-integrated production. the major effect of photoinhibition may be related to the distribution of species. whereas polar species apparently grow well in strong light and long days in combination with low tempera ture. a majority of temperate species d o not (e. sakshaug 8: k . tangen unpubl. data). in essence. photoinhibition of growth in temperate species becomes more pronounced with decreasing tem perature (talling 1957). thus, many temperate species may have a n over-summering problem in cold waters d u e to strong light, whereas polar phytoplankton may have an oversummering prob lem in temperate waters because of high tem perature. relative importance of environmental variables to evaluate the relative importance of optically relevant parameters for the development of spring blooms, we have run mathematical simulations of the early phase of the bloom. w e have assumed an infinite vertical mixing coefficient in the wind mixed (homogeneous) layer and have included the effect of latitude. date and spectral dis tribution of light in the atmosphere (bird 1984) and water, including self-shading by algae (see appendix). two latitudes, 63 and 74"n, and two types of water, "blue" and "green" (fig. 4). have been chosen. algal coefficients represent shade adapted large-celled centric diatoms. the model demonstrates the importance of the depth of the mixed layer for the progress of the spring bloom (figs. 11. 12). in fact, depths of mixingof 150-200 m , which may not be infrequent in deep polar seas in winter, early spring or late autumn (holm-hansen et al. 1977; blindheim 1989: loeng 1989), would preclude blooms large enough t o exhaust t h e mixed layer of winter nutri ents in any polar sea. to exhaust t h e large nutrient concentrations in antarctic waters, depths of mix ing would have to be < i 0 m (kocmur e t al. 1991; sakshaug et al. 1991b). another important factor is the optical quality of the water. because of t h e strong attenuation of blue light in green coastal waters, the chla concentration would surpass 1 mg m-3 about 60 days later in green than in blue water for a mixing depth of 40 m (compare fig. 11b with fig. 12a). a cloud cover which attenuates light by 70%, which may be a realistic average for the atmospheric "low-pressure'' belt, may delay a bloom by at least 20 days and progressively more the deeper the mixing (fig. 1lb-d). moreover, a bloom develops later at a high rather than a low latitude by at least 20 days, depending on the depth of mixing. o n the other h a n d , the delay at high latitudes is in part compensated for by the faster development of the bloom d u e ta the more rapid increase in incident light at high latitudes (fig. 12b-d). because measurements of light and light absorption by algae at the spectral level (pur) require expensive instrumentation and a large amount of data processing relative to measure ments in terms of p a r , we have evaluated the extent to which the two approaches yield different results. the pur approach takes into con sideration the spectral variation i n light with depth (variable %i?), whereas the par approach is based on total irradiance (40c700nm) and a constant g$ derived on the basis of “white” hal ogen lamp incubator illumination (fig. 9). in green water (fig. 12), the difference between the pur and par predictions is small, because a$ light and productivity of phytoplankton 8 1 in the upper layers is not very different from the laboratory estimate. for blue waters. the dif ference is considerable because of the generally higher value of a$ relative to the incubator value (fig. 11b-c). in both cases, precise knowledge of and ambient irradiance at the spectral level becomes increasingly important the deeper the mixing because the average photosynthetic rate in the column will increasingly be determined by the spectrally dependent part of the p-i curve near the origin. consequently, spectral information is particularly important in the case of deeply mixed oceanic waters. the model clearly shows that the progress of fig. 11. progress of spring bloom in “clearest” ocean water as a function of the depth (m) of the mixed layer. a: 74”n (“barents sea”): b d: 63”n (“norwegian sea”). incident light according to bird (1984) except for d (70% reduction). for the southern hemisphere the time scale should read august december. for further explanation, see text and appendix. 1 i i i feb. march april may june 4 b c 3 82 egil sakshaug & dag slagstad feb. march april the spring bloom is most sensitive t o small changes in the light regime when mixing is d e e p , 1.e. the average irradiance in the mixed column is small. i n photosynthetically inefficient regimes such as preen coastal waters. the sensitivity of the model is large even at moderate mixing depths. although phytoplankton stocks may be fairly pre cisely modelled on the basis of crude average values for environmental variables when mixing is shallow, every factor plays an important role when mixing is deep. by ”deep” is meant more than 2 0 m and 8 0 m in green and blue waters, respectively. thus the development of phyto plankton biomass in marginal light regimes may be most difficult t o model realistically. the model indicates that blue ocean waters have a potential for allowing blooms in early march in the northern hemisphere (or early sep tember in the southern hemisphere), provided there is shallow vertical mixing. vertical mixing, however. is simply not shallow enough so early in the season because thermal stratification is out of the question. making meltwater from sea ice the o n l y stabilizing agent. sea ice may start t o melt in april (october in the southern hemi sphere), but usually does not melt appreciably until may in the northern hemisphere and nov ember in the southern hemisphere (zwally e t al. 1983; parkinson et al. 1987). if problems related t o estimating mixing rate and depth can b e adequately solved, it should b e possible to predict gross photosynthesis in the may june fig. 12. progress of spring bloom in “clearest” green water at 63”n (“trondheimsfjorden”) as a function of the depth of the mixed layer (m). for the southern hemisphere the time scale should read august december. for further explanation. see text and appendix. field in crude terms by means of optical data and relatively simple mathematical models. however, the increase in the phytoplankton stock is also very sensitive to variations in loss rates (sedi mentation, grazing). moreover, exponential increase in phytoplankton blooms makes them sensitive to the size of t h e initial stock (sakshaug et al. 1991b). initial stocks in permanently open waters may, for example, b e much smaller than the relatively large seeding stocks which may be derived from melting ice. therefore blooms may develop considerably later in ice-free d e e p waters than in the zone of melting ice. acknowledgemenfs. -this work, which is part of the norwegian research program for marinc arctic ecology (pro mare), was financed by the norwegian fisheries research council and the nonvegian research council for science and the humanities. we would like to thank g. b. mitchell and m. vcrnet (scripps institution of oceanography. la jolla). f. rey (institute of marine research. bergcn). and g . johnsen (trondhjem bio logical station) for providing unpublishcd data. we also thank k . andrcscn for producing the figures and t w o referees for most helpful suggcstions. contribution 248. trondhjem biological station references alexander. v. 1980: interrelationship between seasonal sea ice and biological regimes. cold regiom sci. techno/. 2 . 157 178. arnold. w. 1032: kinetics of photosynthesis in chlorella. cold spring harbor s y m p . quannrarioe b i d . 3. 124-127. light and productivity of phytoplankton 83 homer. r. 1976: sea ice organisms. oceanogr. mar. biol. ann. reu. 14, 167-182. holm-hansen. 0.. el sayed. s. z., franceschini, g . a . & cuhel. r. l. 1977: primary production and the factors con trolling growth in the southern ocean. pp. 11-50 in llano, g. a . (ed.): adaptation within antarctic ecosystem. gulf publ. co., houston, texas. jacques, g. 1983: some ecophysiological aspects of the ant arctic phytoplankton. polar b i d . 2, 27-33. jassby. a. d . & platt, t. 1976: mathematical formulation of the relationship between photosynthesis and light for phyto plankton. limnol. oceanogr. 21, 540-547. jerlov, n. g. 1976: marine optics. elsevier, amsterdam. 231 pp. jerlov, n. g. & steemann nielsen. e. (eds.) 1974: optical aspects of oceanography. academic press. new york. 494 pp . kiefer, d. a . & cullen, j. j. 1991: phytoplankton growth and light absorption as regulated by light, temperature, and nutrients. pp. 163-172 in sakshaug. e . , hopkins, c. c. e. & britsland. n. a. (eds.): proceedings of the pro marc symposium on polar marine ecology, trondheim, 12-16 may 1990. polar research lo(1). kiefer, d. a,, morrow, j . h . , stramski, d . & chamberlin, w. s. 1990: an electron transport hypothesis for seasonal changes in the spectral absorption coefficient of particles in the western sargasso sea. eos 7 1 , 97. kito, j. t . 0. 1975: a theoretical analysis of the contribution of algal cells to the attenuation of light within natural waters. i . general treatment of pigmented cells. new phytol. 75,l i 20. kirk, j . t. 0. 1985: light and photosynthesis in aquatic eco systems. cambridge university press. cambridge. 401 pp. kocmur, s. f., vernet, m. & holm-hansen, 0.1991: racer: nutrient depletion by phytoplankton during the 1989 austral spring bloom. ant. j. u.s. in press. kopf, u. heinze, j. 1984: 2,7-bis(diethylamino)phcnazoxon ium chloride as a quantum counter for emission measure ments between 240 and 700 nm. anal. chem. 5 6 , 1931-1935. langdon, c. 1988: on the causes of interspecific differences in the growth-irradiance relationship for phytoplankton. 11. a general review. j. plankton res. 10, 1291-1312. legendre, l. demers, s . . garside, c.. haugen, e. m., phinney, d. a., shapiro, l. p., therriault, j.-c. & yentsch. c. m. 1988: circadian photosynthetic activity of natural mar ine phytoplankton isolated in a tank. 1. plankron res. 10. leverenz, j. w. 1988: the effects of illumination sequence, c 0 2 concentration, temperature and acclimation on the con vexity of the photosynthetic light response curve. physiol. plant. 74, 332-341. lewis, m. r . & smith, j.-c. 1983: a small volume. short incubation time method for measurement of photosynthesis as a function of incident irradiance. mar. ecol. f r o g . ser. 13, 99-102. lewis, m. r . , warnock, r. e., irwin, b. & platt. t. 1985: measuring photosynthetic action spectra of natural phyto plankton populations. j. phycol. 2 1 , 310-315. ley, a. c. & mauzerall. d. 1982: absolute absorption cross sections for photosystem i1 and the minimum quantum requirement for photosynthesis in chlorella uulgaris. biochim. biophys. acra 680, 95-106. loeng, h. 1989: ecological features of the barents sea. pp. 327-365 in rey, l. & alexander. v. (eds.): proc. 6th conf. com. arcr. l n r . . 13-15 may 1985. e. j. brill, leiden. 1-6. bannister, t. t . & laws, e. a. 1980: modeling phytoplankton carbon metabolism. pp. 243-258 in falkowski. p. g. (ed.): primary productivity in the sea. plenum, new york. berner, t . , dubinsky. z., wyman, k. & falkowski, p. g. 1989: photoadaptation and the package effect in dunaliella tertiolecra (chlorophyceae). j . phycol. 25, 70-78. bird, r . e. 1984: a simple, solar spectral model for direct normal and diffuse horizontal irradiancc. solar energy 32. blindheim, j . 1989: ecological features of the norwegian sea. pp. 366-401 in rey, l. & alexander, v. (eds.): proc. 6th conf. com. arc. int., 13-15 may 1985. e. j. brill, leiden. bodungen, b. von. smetacek. v., tilzer, m. m. & zeitzschel. b. 1986: primary production and sedimentation during spring in the antarctic peninsula region. deep-sea res. 33, 177 194. braarud, t. 1935: the “ 0 s t ” expedition to the denmark strait 1929. 11. phytoplankton and its conditions of growth. hualrdd. skr. 10. 1-173. braarud. t . & klem, a. 1931: hydrographical and chemical investigations in the coastal waters off more and in the romsdalsfjord. hualrdd. skr. 1, 1-88. bricaud, a , , morel, a. & prieur. l. 1983: optimal efficiency factors of some phytoplankters. limnol. oceanogr. 28, 816 832. campbell, j. w. & aarup. t. 1989: photosynthetically available radiation at high latitudes. limnol. oceanogr. 34.1490-1499. cullen j . j. 1990: models of growth and photosynthesis. deep sea res. 37. 667-683. cullen. j . j . & lewis, m. r. 1988: the kinetics of algal photo adaptation in the context of vertical mixing. 1. plankron res. 10. 1039-1063. dubinsky, z . , falkowski. p. g . & wyman. k. 1986: light harvesting and utilization by phytoplankton. planr cell phys iol. tokyo 27, 1335-1349. eppley, r. w. 1972: temperature and phytoplankton growth in the sea. fish. bull. n o a a 70. 1063-1085. falkowski, p. g. &owens. t . g . 1980: light-shade adaptation: two strategies in marine phytoplankton. pianr physiology 66. gallegos. c. l., platt, t.. harrison, w. g. & irwin, b. 1983: photosynthetic parameters of arctic marine phytoplankton: vertical variations and time scales of adaptation. limnol. oceanogr. 28, 698-708. gieskes. w. w. c., veth, c., woehrmann. a . & graefe, m., 1987: secchi disc visibility world record shattered. eos 68, 123. gilstad, m & sakshaug. e. 1990: growth rates of ten diatom species from the barents sea at different irradiances and day lengths. mar. ecol. f r o g . ser. 6 4 , 169-173. gran, h . h. (1931): on the conditions for the production of plankton in the sea. rapp. p.-u. rdun. cons. l n f . explor. mer 75, 37-46. harrison. w. g . & platt, t. 1980 variations in assimilation number of coastal marine phytoplankton: effects of environ mental co-variates. j. plankron res. 2 , 24%260. harrison, w. g . & platt, t. 1986: photosynthesis-irradiance relationships in polar and temperate phytoplankton popu lations. polar biol. 5 , 15s164. hegseth, e. n. 1989; photoadaptation in marine arctic diatoms. polar biol. 9. 479-486. hegseth. e. & sakshaug. e. 1983: seasonal variation in light and temperature-dependent growth of marine planktonic dia toms in in situ dialysis cultures in the trondhcimsfjord. nor way (63”n). j. exp. mar. biol. ecol. 67. 199-220. 461-471. 592-595. 84 egil s a k s h u g ce dag slnprtnd maake. h . c haardt. 11 t i 19x7: o u a n t i t a t i \ c i r i i , i i , o absorp tion lpcctra ot phytoplankton. dctrital ahsorption dnd com parison n i t h fluorcwcnce c\citation spectra. lirnriol. oceanogr. 32. 6 3 m 3 3 maykut. g . a l grcnfell. t c'. i975 t h e spectral distribution o f light beneath first-year sea ice in thc arctic ocean. limnol oceanogr. 20, 5 5 l 6 3 . mitchell, g . b & kietcr. d. a . iyxx. chloroph!ll 11-specific ahsorption and fluorescence excitation spectra for iight-lim ited phytoplankton deep-seu rer 3 5 . 6 3 m 6 3 . morel. a . 1978: available. usable and radiant energ! in relation to marine photos)nthesis. d e e p s e a res. -7.5. 673-688. morel. a . 19rx. optical modeling of the upper ocean in relation to its hiogenous matter c n n t e n t ( c a w i ~ a t e r s ) . j . g e o p h v s . re$. 9.3 (cy), 10741)-11v6h morrow. j h . . chamhcrlin. w s & kicfcr. d a . 1y8y: a t w o c o m p n c n t dc\cription of spectral absorption h ) marine particles. limiiol oceunogr. 34. lfiml150y myers. j . & g r a h a m . j r . 1971. t h e photos)nthctic u n i t of c'/ilorella m e a w r c d b! r c p c t i t n c short flashcs. p l u m plii>rol. 48. 282-2x6 h'emoto. t kr harrison. h c; i y x i . fiigh l a t r t u d c c c o s ~ s t c m s pp 95-126 in longhur\t. a r ( c d . ) : annlysir of m a r i n e i . ( u , u / e m ~ academic press. kcu york s e o r i . a . c holm-hanscn. 0. 19x2: effcct of temperature on rate of photos!nthcsis i n antarctic phytoplankton f o l l i r b i d . i . 3 3 3 8 . ncori. a . vernct. m . . holm-hansen. 0. 8: haxo, f . t . i y x x : comparison of chlorophyll far-red a n d red fluorescence exci tation spectra with photosynthetic oxvgen action spectra for photosystem i i i n algae. m a r . erol f r o g . ser. 4 4 . 297-302. palmisano. a . c . soohoo. j . b . . moe. r . l. & s u l h a n . c . w. 1986: sea ice microbial communities v l l . changes i n under-ice spectral irradiance during thc development of ant arctic sea ice microalgal communities. mar. ecol. prog. ser. 35. 16s173 parkinson. c l.. comiso. j c . z w a l l y . h . j . . cavalieri. d j . . gloersen. p & campbell. w j 1987: arcrir sea ice. 1973-1976sarellire p a s s i o r m i c r o n ~ a i ~ e o b s e r t m o n s . nasa sp-489, scientific and technical information branch. wash ington. d . c ?y6 pp. platt. t . & suhba r a n . d . v . 1975. primary production of marine microphytcs p p 24y-28u in c o o p e r . j p ( c d . ) : phoros~nrhesii utid froducrii~iii in differeiir eriivromnenrs cambridge l!nirersity press. cambridge. platt. t . . gallcgos. c . l . c harrison. w . g . iyro: photo inhibition of photos)nthesis in natural assemblages of marine phytoplankton j m u r . h e , . 3x. 687-7(11. platt. t . . harrison. w g . , irwin. b . . h o r n c . e . p. & gallcgos. c' l 19x2. photos!nthcsis a n d photoadaptation of marine phytoplankton in the arctic. deep-seu res. 2y. 1151)-1170 post. a . f.. duhinsky. 2 . w l m a n . li 8: falkow'ski. p. g iyki: kinetics of light-intensit! adaptation in a marine plankton diatom. m a r . biol. 8.3. 231-238 rile). g a . 1042: t h e relationship of \ertical turbulence a n d rpring diatom rouering\ j .mar. res 5 . 67-87, rilc!. g a 1y46 factors controlling phytoplankton popu lations o n georgcs b a n k . j . .mar. res. 6. 54-73. rochct. m . . lcgcndre. l . & dcmers. s. 1986: photos!nthetic and pigment responses of sea-ice microalgae to changes i n light intensit! and qualit) j. crp. .mar. biol. ecol. 101. 2 1 1 226 sakshaug. e iyxy t h e phvvological ecolog\ of polar p h > t o pldnkton p p . 61-89 in r c ? . l. l alcxandcr. v . ( c d s . ) . proc. 6rli cotif, cum arcr. i t i r , 1 3 / s ,mav iyx5. e . j . brill. lcidcn sakshaug. e b. andresen. k. iy86. effect of light regime upon thc g r o u t h ratc and chcmical composition of a clone of .sa121eronema cosruriim from the trondheimsfjord. j. flunkroti r r , . 8. 619-637. sakshaug. e. l holm-hansen. 0. 1984: factors governing pelagicproduction in polaroccanc. p p . 1-1xin holm-hansen, 0 . . boliz. l. 8; gilles. r . ( c d s . ) . marine fhyroplankroti and froducriivri springer. berlin. sakshaug. e l holm-hanscn. 0. iyx6: photoadaptation i n antdrctic phytoplankton: variations in growth rate. chemical composition. and p v s i curves. j . pluiikrori hes. 8. 459 473 sakshaug. e . demers. s . & yentsch, c. m . 1087: tlialassiosira oceunicu and t . p s e u d o f i u t i a : t w o different photodd aptational rcspomes. m a r . ecol. frog. ser. 4 1 . 27s-282. sakshaug. e.. andresen. k. & kiefer. d . a . 1yry. a steady state description of growth and light absorption in the marine planktonic diatom skelerotiemu cusrarum. limfiol. oceanogr. 3 4 . lyb205 sahshaug. e . johnsen. g . . andresen. k . kr vcrnct. m . 1991a: modeling of light-dcpcndcnt algal photosynthesis and growth: experiments with thc barcntq sca diatoms thal ussrosiru norrle~iikioeldii a n d chuerocero& firrcellurur. d e e p sea rei 38. 415-430. sakshaug. e . slagstad. d. & holm-hanscn. 0. 1yyih: factors controlling the development of phytoplankton blooms in the antarctic ocean a mathematical model. m a r . chem. in press sath!cndranath. s 8: platt. t 1989: computation of aquatic priniar) production. extended formalism to include effect of angular and spectral distrihurion of light. l i m w l . o c e a n o g r . 3 4 . 188-39k. smetacck. v. & passow. u . 1990: spring bloom initiation and sverdrup's critical-depth model. limnol. oceanogr. 35.228 233 smith. r . c . & baker. k. s . 19x1: optical properties of the clearest natural waters (?(mb81)0 n m ) . a p p l . oprics 2 0 . 177 1 u4 smith. r . c . marra. j . . perry. m . j . . baker. k. s . . swift, e.. buskey. e & kiefer. d . a . 1989: estimation of a photon budget for the upper ocean in the sargasso sea. limnol. oceatiogr. 3 4 . 1673-1693. smith. w . 0. & sakshaug. e . 19y0: polar phytoplankton. pp. 477-525 in smith. w. 0.: polar o c e a n o g r a p h y . parr b: cliemisrri . biology and g e o l o g y . academic prcss. new york soohoo. j b . . palmisano. a . c.. kottmeier. s . t . . lizotte. m. p . s u o h o o . s . l . & sullivan. c. w 1987: spectral light ahsorption and q u a n t u m yield of photosynthcsis in sea ice microalgae and a bloom of phaeocysrrs poiccherii from mcmurdo sound. antarctica. m a r . ecol. p r o g . ser. 39. 175 1x4, spies. a . lyx7: g r o w t h rates of antarctic marine phyroplankton in the wcddcll sea. m a r . ecol f r o g . ser. 4 1 . 267-274. s u h b a r a o . d v . & platt. t. 1984: primary production of arctic walcrs. f d a r &i/. .?. 191-201. svcrdrup. h. u. 1053: on conditions for thc vernal blooming of phltoplankton. j. cons. perm. inr. explor. m e r 18. 287 295 talling. j f 1y57: photosynthetic characteristics of some fresh water plankton diatoms in relation to underwater radiation. .yew f h y r o l 56. 2%50. tilzer. m . m 8: duhinsky. z. iyx7: effects of temperature and day lcngth on thc mass balance of antarctic phytoplankton. polar t?io/. 7. 35-42, light a n d productivity of p h y t o p l a n k t o n 85 sumably does not significantly cxceed the dark resprration ratc of polar phytoplankton. spectral distribution at the sea surface (no clouds) is a func tion of sun elevation (bird 1984) and model output is the s u m of direct and diffuse irradiance. water vapour pressurc in the atmosphere has been set at 1.42 cm and turbidity r,(0.5) cquals 0 . 1 . reflection losscs at the surface arc set at 5510% dcpcnding on sun elevation (kirk 1985). spcctral distribution of downwelling light is calculated by a model similar to that of sathyendranath & platt (1989): total downwelling i(2.a) at depth z and wavelength i is partitioned into a direct component id and a diffuse component 1,: i(2.a) = l d ( 2 . a ) + i,(z,i). (13) vertical attenuation coefficients for diffuse and direct light are given by k,(z.a) = [a(z.a) + bh(z.h)]/cosud k , ( z . i ) = (a(2.i) + b,,(zj.)]/b ( 1 4 ) and ( 1 5 ) where a ( z , l ) is the volume absorption coefficient at depth z and wavelength a , and bh(z,a) is thc corresponding backscattcring coefficicnt. 0, is thc sun zenith angle in water and p i s the mean cosine of zenith angles of diffuse light 0, after refraction at the surface (set at 0.6: kirk 1985). multiple scattcring is neglected. a ( i ) is the sum of the absorption coefficient of pure water aw(a). either "clearest" blue o r "clearcst" green water (fig. 4). and absorption due to particles * a r . (chla*:c). chla' is thc sum of the chla concentration and half the concentration of phaeophytin a . *a,is0.0098 m 2 (mgchla*)-' in "white" halogen lamp illumination. the phaeophytin a concentration in the barents sea is related to chlu according to the function ( f rey, unpublished data) phaeoa = 0.45 chla + 0.02 (mg m > ) (16) algal coefficients are representative for shade-adapted cclls of the large-celled centric diatoms tha/assiosirn anforcficn and t . nodenskioeldii (at 25 ymol m-'s-') using the scaled fluor escence excitation spectrum "f for 'u in equations 6 and 8. "f and 'a, for white halogen lamp illumination are 0.0058 and 0.0090mz ( m g chlo)-', respectively. the chl ratio is 0.052 mg mg-i, e&,d, is 0 . 0 4 g-at c (mol photons)-'. and the product qr is 1370 mg(mol psu).' h. thus the growth-relevant values rpc and ens ("white" light) are 0 . 3 5 m g c (mg chia)-l h ' and 0.010 mg c (mg chlu).' h ' (fmol m ? s ' ) ' . respectively. the maximum (light-saturated) gross growth rate is 0.44d-i. the equations were solved by a finite difference scheme using a microvax computer. the vertical grid point was 5 m and time step was 1 h. the initial concentration of chla was 0.05 mg m > . tylcr. j . e. ( c d . ) 1977: ligl7f in fhe sea. dowdcn, hutchinson & ross. stroudshurg. pennsylvania. 384 pp. vernet. m . , ncori, a . & haxo, f. t. 1989: spcctral propcrtics and photosynthetic action in rcd-tidc populations of proro cenfrutn micafis and g o ~ 7 y a u / a s p o l y e d r u . m a r . biol. 193, 365-371. webb, w. l . , newton, m. & starr. d. 1974: carbon dioxide exchange of abtus rubm: a mathematical model. oecologia 17, 281-293. weger, h . g . . herzig, r . falkowski, p. g. & turpin. d. h . 1989: respiratory losses in the light in a marine diatom: measurements by short-term mass spectrometry. limnol. oceanogr. 34. 1 1 5 ~ l 1 6 1 . wilson, d . l . . smith. w. 0. & nelson, d . m . 1986: phyto plankton bloom dynamics of the western ross sea edge. 1. primary productivity and species-specific production. deep seri res. 33, 1375-1387. ziemann, d. a , , conquest. l. d., bienfang, p. k . & kanda. j . 1987: patterns of primary production and sedimentation during the 1987 spring bloom in aukc bay. alaska. pp. 29 194 in apprise nfifiual r e p o r f . sfos app87-100. school of fisheries and ocean sciences, unrvcrsity of alaska, fair banks. zwally, h . j . , comiso. j . c.. parkinson. c . l . . campbell, w. j . . carsey. f. d . & glocrsen. p. 1983: anfarcric sea ice. 1973-1976: safellife passioe-microwaue obseroafions. nasa sp-459, scientific and technical information branch. wash ington. d.c. 206 pp. appendix: formu/afion of model assuming negligible lateral coefficients. phytoplankton dis tribution is affccted hy vertical turbulent mixing and vertical transport as in the 1-d model where p(1.z) is phytoplankton concentration at depth z and time t , w is vertical (usually sinking) velocity, k,(z) is the vertical turbulent mixing coefficient. and fhllll describes net phyto plankton growth. the vertical mixing coefficient is infinite above the depth of mixing and zero elsewhere. for the early phase of the spring bloom. nutrient limitation is ignored. thus f h l c 4 = p(t.z){['pc (e,,(h),t.z)] r) (12) where [ppc (e,,(a),t,z)] is the turnover rate of growth-relevant carbon ( h ' ) as a function of spectral irradiance. time and depth (see equations 6 . 7 and 8 ) . r rcprcscnts in principle the total loss ratc. i.c. the sum of dark respiration. sedimentation and grazing rates. hut is set at a low value. 0.0046 h-'. which pre no job name effects of disturbance on geese in svalbard: implications for regulating increasing tourismpor_120 376..389 jesper madsen,1 ingunn tombre2 & nina e. eide3 1 department of arctic environment, national environmental research institute, aarhus university, frederiksborgvej 399, dk-4000 roskilde, denmark 2 department of arctic ecology, norwegian institute for nature research, polar environmental centre, no-9296 tromsø, norway 3 department of terrestrial ecology, norwegian institute for nature research, tungasletta 2, no-7485 trondheim, norway abstract tourism in the arctic archipelago of svalbard, norway, has increased significantly in the last decade. cruise ships make landings all around the archipelago, and there are numerous snowmobile, boat and hiking excursions. we describe disturbance effects on the three geese species that breed in svalbard: the pink-footed goose (anser brachyrhynchus), the barnacle goose (branta leucopsis) and the light-bellied brent goose (branta bernicla hrota). all three are regarded as highly vulnerable to disturbance. behavioural responses by geese to humans on foot were analysed by estimating the distances at which geese become alerted, the escape flight distances and the length of escape flights, during pre-nesting, nesting and brood-rearing periods. we evaluate the consequences of human intrusion on the reproductive success in breeding colonies. during all three phases, pink-footed geese responded at longer ranges, and flew/ran longer distances, than both brent and barnacle geese: when disturbed on the nest site, both male and female pink-footed geese flew far away, resulting in a high rate of nest loss to avian predators (35%), compared with the 4 and 0% losses among barnacle and brent geese, respectively. during brood rearing, families of pink-footed geese escaped at an average distance of 1717 m, compared with distances of 620 and 330 m for brent and barnacle geese, respectively. even though bird sanctuaries have been established on several islets, with no human access during nesting, many core areas for the three species remain without restrictions, such as islets used by brent geese and slopes and valleys with nesting pink-footed geese, broodrearing areas and moulting grounds for non-breeding geese. we propose regulations of human access to goose concentration areas, and address the need to better protect these significant areas. we also discuss the need for further research on the vulnerability of geese to human activity. keywords barnacle goose; brent goose; disturbance impact; pink-footed goose; recreational activities; tourism. correspondence jesper madsen, department of arctic environment, national environmental research institute, aarhus university, frederiksborgvej 399, dk-4000 roskilde, denmark. e-mail: jm@dmu.dk doi:10.1111/j.1751-8369.2009.00120.x as a result of norwegian political incentives to encourage the development of tourism as the primary business activity in svalbard, tourism in the area has increased during recent decades in terms of boat and snowmobile trips organized by tour operators, as well as individual excursions not arranged by tour operators (governor of svalbard 2006). furthermore, there has been an increase in research and educational activities in the area through the creation of research facilities, in the settlements of ny-ålesund and longyearbyen in particular. however, there is limited information about the disturbance effect of these human activities on the fauna of svalbard (review by overrein 2002; andersen & aars 2008; vistad et al. 2008) or the arctic in general, except for some studies of the effects of relatively localized industrial development (e.g., madsen 1984; wolfe et al. 2000; johnson et al. 2005). geese are regarded as one of the species groups that are most vulnerable to disturbance (overrein 2002). three species breed in svalbard: the pink-footed goose (anser brachyrhynchus), the barnacle goose (branta leucopsis) and the light-bellied brent goose (branta bernicla hrota). they constitute three distinct populations, wintering in different areas in north-west europe (madsen et al. 1999). all polar research 28 2009 376–389 © 2009 the authors376 mailto:jm@dmu.dk three populations have experienced increased population sizes in recent decades, but still remain small in comparison with other western palearctic goose populations. the three species breed in different parts of svalbard, with a partial spatial overlap occurring during parts of the breeding season (mehlum 1998). the three species also exhibit specific characteristics in terms of habitat use and behaviour (fox et al. 2006; fox et al. 2007). as a consequence, they have a different exposure and vulnerability to human activity, which, in turn, means that disturbance effects and potential consequences for the populations may vary. even though many of the geese breed in reserves or national parks in svalbard, in which human access is strictly regulated, geese are increasingly exposed to human disturbance, partly because they breed or moult in areas without regulations, and partly because restrictions may not be sufficient in the existing reserves. in this paper we describe the ecology of the three goose species, and assess the spatial and temporal overlap between recreational activities and geese in svalbard during the summer. we evaluate the potential effects of tourism on geese in terms of the behaviour and reproductive output of the birds, and propose guidelines to regulate tourism and other human activities that may otherwise conflict with the long-term conservation of geese in svalbard. we define disturbance as any human activity that constitutes a perceived predation risk that is sufficient to disrupt normal activities (frid & dill 2002). furthermore, we distinguish between disturbance effects, i.e., changes in behaviour or local displacement in response to human activity, and impacts, i.e., fitness consequences of disturbance in terms of reduced body condition, reproductive potential or survival. material and methods study populations pink-footed goose. the svalbard breeding population of pink-footed geese winters in denmark, the netherlands and belgium. in spring, the population migrates via norwegian stopover sites to the breeding grounds. the population size has increased from ca. 20 000 in the 1970s to a hitherto unprecedented peak of ca. 60 000 in 2007 (madsen et al. 1999; madsen unpubl. data). on arrival in svalbard in mid-may, the geese spend around one week intensively foraging before they start laying eggs. adventdalen in isfjorden is a major pre-nesting site, from where the geese disperse to the nesting grounds (fox et al. 2006; glahder et al. 2006). the geese nest in the lowland open tundra areas, preferring south-facing slopes and slopes under bird cliffs (mehlum 1998; madsen et al. 2007; wisz et al. 2008). in svalbard, the distribution is concentrated in western spitsbergen, with small colonies occurring in the north and south of spitsbergen, as well as on the west side of edgeøya. the present distribution seems to be limited by the length of the frost-free period during summer (jensen et al. 2008). after hatching, families feed in lowland marshes and moss fens, under bird cliffs, and often move far inland, away from open water (jepsen et al. 2002; fox et al. 2007; fox et al. 2009; madsen unpubl. data). some nonbreeding pink-footed geese migrate to the east and northeast of svalbard, where they congregate in flocks along the coast to moult flight feathers from late june to late july; some non-breeders stay within the breeding range, and congregate on larger lakes, rivers and along the shoreline (mehlum 1998; glahder et al. 2007; madsen unpubl. data). little information exists about the distribution of pink-footed geese prior to autumn departure, but it seems that large flocks congregate in the northern fjords of spitsbergen, in the lowlands along the west coasts, especially under bird cliffs, and in the lowlands of edgeøya and barentsøya (mehlum 1998; glahder et al. 2007). barnacle goose. the svalbard breeding population of barnacle geese winters in south-west scotland/northwest england, with spring staging areas along the west coast of norway. the population numbered less than 1000 individuals during the 1950s, but increased to around 14 000 at the start of the 1990s (owen & black 1999). since 2000, the population has increased to reach a level of around 25 000–30 000 (griffin & mackley 2004). during the second half of may, barnacle geese arrive along the west coast of svalbard, with known major pre-nesting congregation sites in hornsund and vårsolbukta (glahder unpubl. data; hübner 2006). barnacle geese nest on islets along the west coast of spitsbergen, in storfjorden and hinlopen. many colonies have been established on cliffs along coasts and in valleys. brood-rearing areas are found in association with coastal lagoons and lakes, and families stay in close proximity to open water to avoid predation by arctic foxes (vulpes lagopus). some of the oldest colonies and associated brood-rearing areas along the west coast have reached saturation, with an apparent density-dependent regulation of bird numbers (loonen et al. 1997; drent et al. 1998). non-breeding barnacle geese congregate in separate flocks, but appear to remain within the breeding range. during late summer, large flocks occur in several places in the lowlands along the west coast of spitsbergen (mehlum 1998). disturbance of breeding geesej. madsen et al. polar research 28 2009 376–389 © 2009 the authors 377 light-bellied brent goose. the svalbard breeding population of light-bellied brent geese is part of the north-east atlantic flyway population, which also breeds in low numbers in north-east greenland, and winters in denmark and north-east england. the brent goose was probably the most numerous of the three species at the beginning of the 20th century, but the population then crashed, and numbered only 2000–4000 individuals in the 1960s. the species is classed as being near threatened in the norwegian red list (kålås et al. 2006). subsequently, the population has increased to reach a population size varying between 6000 and 9000 in 2000–07 (clausen et al. 1999; clausen unpubl. data). in svalbard, the pre-nesting congregation sites used during the last week of may occur on the west coast. the majority of brent geese nest in small colonies in tusenøyane in south-east svalbard, on moffen in the north and are scattered on islets along the west coast. in addition, small numbers of nests have been found in the interior valleys in spitsbergen, close to the glaciers (madsen unpubl. data). in tusenøyane, families stay on the islets, feeding along the shorelines or in moss carpets around ponds. flocks of non-breeding moulting geese have been observed in the northern fjords of spitsbergen and along the west coast of edgeøya. during late summer, brent geese appear to congregate in the northern fjords of spitsbergen and edgeøya, but flocks have also been observed scattered all over svalbard (mehlum 1998). geese are monogamous, and are generally faithful to their natal nest site. only the female incubates the eggs. clutch sizes vary between two and six eggs, which are incubated for approximately 25 days. during the nesting period, the female only leaves the nest for short periods to drink and feed. males are slightly larger than females, and defend the territory and nest against intruding avian predators and other geese. pink-footed geese are slightly larger than barnacle and brent geese, and can defend themselves against arctic foxes, which explains their dispersed inland nesting and post-hatching distribution. nesting brent and barnacle geese are confined to islets and cliffs where foxes have no access, and during the brood-rearing period goose families stay close to open water, which offers an easy escape. study areas the data on disturbance effects originate from various goose studies performed in svalbard (fig. 1), where disturbance reactions were recorded on an ad hoc basis in conjunction with other field activities. case 1. brent and barnacle geese nesting in tusenøyane (77°05′n, 22°00′e), a group of small islands in south-east svalbard, were studied in 1987, 1989 and 1991. fieldwork was carried out on the lurøya, kalvøya and hornøya islets in the tiholmane island group of tusenøyane. the islets are low and rocky, with varying degrees of polar desert vegetation cover, consisting of wet moss carpets and fjellmark dominated by mosses and lichens (madsen et al. 1989; bregnballe & madsen 1990; madsen et al. 1992; madsen et al. 1998). in 1987, a total of 98 nests of brent geese and 17 nests of barnacle geese were found in tiholmane (madsen et al. 1989). in 1989, there were arctic foxes on most of the islands, and virtually no geese bred there (madsen et al. 1992). case 2. barnacle geese nesting on islets in kongsfjorden (78°55′n, 12°15′e) were studied in 1992. geese breed on several islets near the settlement of ny-ålesund. in the present study we focus on barnacle geese breeding on two islets, storholmen (30 ha) and prins heinrichøya (3 ha), with 60 and 27 nests, respectively (tombre, black et al. 1998; tombre, mehlum et al. 1998). common eider (somateria mollissima) also breed on the islets, which have exposed ridges and heterogeneous vegetation, including moss tundra (tombre & erikstad 1996; alsos et al. 1998). case 3. pre-nesting and nesting pink-footed geese and barnacle geese in sassendalen (78°18′n, 17°00′e) were studied in 2003–06. sassendalen lies 30–40 km east of longyearbyen, in central svalbard, and is a classic u-shaped glacial valley. it is ca. 4 km broad, with steep slopes rising on both sides to 400–500 m a.s.l. the vegetation is high-arctic tundra, with well-developed fens supporting grass and carex species. the valley floor supports a matrix of moss tundras, fens, marshes and unstable vegetation on braided melt rivers and river banks, with dry ridge areas and a few small lakes (the largest, store gåsdammen is ca. 150 m in diameter, and is an important nursery area for barnacle geese). peripheral river valley canyons run into sassendalen, three of which contain sympatric nesting barnacle and pinkfooted geese. some 380 pairs of pink-footed geese nested in loosely aggregated colonies on the open tundra in the outer part of the valley, compared with ca. 60 pairs of barnacle geese restricted to the steep cliff sides of sassendalen. nests of both species were loosely aggregated because of habitat, with nests of the same species being as close as 5 m from one another (fox et al. 2009; madsen et al. 2007; wisz et al. 2008). case 4. opportunistic observations of pink-footed and barnacle geese were carried out in connection with banding of geese at various sites in isfjorden (daudmannsøyra, gipsdalen and sassendalen) and the west disturbance of breeding geese j. madsen et al. polar research 28 2009 376–389 © 2009 the authors378 fig. 1 the three study sites in svalbard where data on disturbance effects on geese were collected are encircled: case 1, tusenøyane: case 2, kongsfjorden; case 3, sassendalen. the blue dots represent the geographical distribution of cruise ship tourists at different landing places in 2007 (the most recent year with geographical data). data source: governor of svalbard (2006, 2007, unpubl. data). disturbance of breeding geesej. madsen et al. polar research 28 2009 376–389 © 2009 the authors 379 coast of spitsbergen (recherchefjorden and dunderbukta) in july–august 2007 (madsen unpubl. data). field methods we used the escape flight distance (efd) as an expression of the behavioural tolerance limit of geese towards approaching humans. it is well known that efd varies with species, flock size, site and physiological state (madsen 1985, 1998; beale & monaghan 2004; laursen et al. 2005), and hence can only be used as an indicator, which should not be used on its own, to assess disturbance effects (gill et al. 2001); however, it is useful in a management context to regulate human access to sensitive areas (fox & madsen 1997; blumstein et al. 2003). to supplement efd, in some cases we recorded (1) the distance at which geese stopped their undisturbed behaviour (typically resting or foraging) and became alert (standing up, looking with stretched neck towards the intruders), and (2) the distance over which geese fled before they settled. the latter indicates a cost in terms of energetics or the risk that the bird takes in terms of losing eggs or chicks in the unprotected nest to predation. we estimated the efd at 1-m intervals for distances of 0–10 m between source of disturbance and the flushing bird, at 10-m intervals for 10–200-m distances (except for the islets in kongsfjorden, where a 1-m interval was used up to 50 m, as there were good landmarks for these sites), and 50or 100-m intervals for distances greater than 200 m. after having flushed the birds, efds were paced out, judged by landmarks with known distances or gauged using detailed field maps. the distances at which geese became aware or the fleeing distances were estimated using landmarks and from detailed field maps. we only used efd records where the geese were approached in full openness in advance of the escape. in each case, we recorded the date, species, flock size (which was one for nesting birds) and status, categorized as non-breeding individuals capable of flight, incubating females, nestguarding males, families with goslings or non-breeding moulting geese unable to fly. humans on foot were the sole source of disturbance, in congruence with how work was carried out in the study areas. geese were approached by a single person or two people walking together. as data was mostly collected opportunistically as additional information collected during other work, there was no strict protocol for the selection of geese for study. data were primarily collected by the authors. efds and fleeing distances were calibrated between jm and nee in sassendalen, whereas there was no calibration between jm/nee and imt. however, imt paced out all efds. hence, we are confident that the estimated efds and fleeing distances are comparable between studies. to estimate the impact of disturbance on reproduction, we recorded egg loss to predation resulting from humaninduced departure from the nest. revisiting the nesting area within the next 24 h gave us an opportunity to note whether the geese returned to the nest (this could be observed from a distance) or whether the nest had been predated (observation based on a closer inspection of the nest), and, if so, by which predator (judged by eggshell remains). potential predators were glaucous gulls (larus hyperboreus), arctic skuas (stercorarius parasiticus), great skuas (stercorarius skua) and arctic foxes. we never visited nests solely to simulate disturbance events, but also checked clutch sizes or collected eggs for scientific purposes. when we scared a nesting female off the nest, we always covered the eggs with down to maintain the egg temperature and to lower the risk of predation, and we left the nest site as quickly as possible. in this respect, our activity may not simulate an erratic human approach, in which the intruder may not notice the goose nest, nor be aware of the need to cover the nest. therefore, our estimates of egg loss due to human intrusion are conservative. statistical analyses data on alert distances, efds and fleeing distances are presented as means � standard errors, as well as medians, 25 and 75% quartiles and ranges. correlations among various variables were carried out by the use of linear regressions. for comparison among groups we use student’s t-tests when two categories are involved, and use anovas for three categories. to determine whether sex or breeding site have any effect on efds, we used a general linear model (glm, type iii, sum of squares). the organization of data, statistics and the creation of figures were achieved using sas statistical software (sas institute 2004) and the statistical package r development core team (2008). tourism data the svalbard tourism council, a consortium of local tourism companies operating on land, and the association of arctic expedition cruise operators (aeco), an umbrella company of the small coastal cruise ships operating around svalbard, have reported travel statistics to the governor of svalbard since 1996 (governor of svalbard 2006, 2007, unpubl. data). some of these data have also been reported to miljøovervåkningen av svalbard og jan mayen (the environmental monitoring of svalbard and jan mayen [mosj]; sander et al. 2005). these data reveal disturbance of breeding geese j. madsen et al. polar research 28 2009 376–389 © 2009 the authors380 trends in the development of the tourism industry in terms of abundance and distribution, as well as seasonal patterns. the data with the best geographical resolution were reported landings from cruise ships, whereas data on land-based activities were only reported according to management zones (there are 10 different zones of variable size and protected status; see http://svalbard. miljostatus.no for details.) statistics on the seasonal number of cruise-ship landings were only available for 2007. for the present study we had access to all the reported data, and have aggregated the data in time (sums per months, years) and space (regionally) to evaluate potential temporal and spatial overlaps, and conflicts between human activity and goose distribution and occurrence. it should be emphasized that this only gives information on tourism activity and does not measure the overall level of human traffic. results human activities tourism was categorized in winter and summer activities. most visitors to svalbard stay on cruise boats. more than 50 000 people visited svalbard during the summer months of 2007 (governor of svalbard 2007). there were 95 000 landings that year (fig. 2). the cumulative number of landings from cruise ships has more than doubled over the last 10 years, whereas the number of new landing sites has more than tripled over the same period (fig. 2). in recent years, visitors landed at more than 160 different locations (fig. 2). landings took place all around the archipelago, but the load of traffic differed between landing sites (fig. 1). the official statistics covering the period 2003–07, based on reports from tourist operators, illustrate the seasonal patterns of various outdoor activities (fig. 3). the winter season, during which visitors engage in snowmobile and dog-sledging excursions, lasts from january to may, with a peak in march and april. however, dog sledging extends into may/june, as tour operators take advantage of snow-covered glaciers. snowmobiles bring most people visiting svalbard into the arctic landscape, whereas hiking is relatively limited during winter. tourist activity peaks during the summer: june, july and august (figs. 3, 4). summed from june to october, there are 8700 visitor-days spent in organized hikes and rubber boat and kayak excursions starting from isfjorden (fig. 3). individual travellers visiting management area 10 (isfjorden) added to the number registered at the office of the governor of svalbard and the aeco. accordingly, the picture of the geographical distribution of tourism activity was blurred by the fact that activities within management area 10 were not fully recorded: only activities through organized tour companies were registered. disturbance effects: pre-nesting period from the pre-nesting period, data were available from lurøya (brent geese) and sassendalen (barnacle and pink-footed geese) over the period from 24 may to 9 june. only six records of brent goose flocks were made. hence, in statistical tests only data from pink-footed geese and barnacle geese were included (with sample sizes of between 40 and 88). pink-footed geese were found in larger flocks than barnacle geese and brent geese (pink-footed geese, 18 � 2.7 geese, range 2–143, n = 88; barnacle geese, 7 � 1.4 geese, range 1–48, n = 41; brent geese, 4 � 1.4 geese, range 2–11, n = 6). the difference in flock size between pinkfooted geese and barnacle geese was highly significant (student’s t-test, t = -3.70, df = 122, p = 0.0003). moreover, the pink-footed geese were alert to an approaching person at greater distances than the barnacle geese in the same area, with extremes at distances of 1500 m (pink-footed geese, 388 � 32 m, range 40–1500 m, n = 88; barnacle geese, 275 � 34 m, range 30–1000 m, n = 38; student’s t-test, t = -2.24, df = 111, p = 0.027; fig. 5). the alert distance was highly correlated with the efd for both pink-footed and barnacle geese (linear regression, pink-footed geese, r2 = 0.80, n = 75, p = 0.0001; barnacle geese, r2 = 0.87, n = 38, p = 0.0001), and the efds were significantly greater for pink-footed geese than for barnacle geese (student’s t-test, t = -2.48, df = 101, p = 0.015; fig. 5). for pink-footed geese, there was a positive and significant relationship between flock n o . o f la n d in g s fr o m c ru is e s h ip s (b la c k) n o . o f la n d in g s ite s u se d in c ru is e t o u ri sm ( g re y) 0 20 000 40 000 60 000 100 000 80 000 0 50 100 150 250 200 1996 1998 2000 2002 2004 2006 fig. 2 the development of cruise ship activities in svalbard, 1996–2007, expressed as the total annual numbers of cruise ship landings and number of landing places used around svalbard. the data from isfjorden (management area 10) are separated (dotted lines). data source: governor of svalbard (2006, 2007, unpubl. data). disturbance of breeding geesej. madsen et al. polar research 28 2009 376–389 © 2009 the authors 381 http://svalbard size and efd, with geese in large flocks becoming alert at greater distances than geese in small flocks (r2 = 0.10, n = 85, p = 0.004). no relationship between flock size and efd was found for barnacle geese or brent geese (p > 0.8). disturbance effects: nesting period escape distances. for barnacle geese, there were no significant differences in efds between birds from the 0 500 1000 1500 2000 0 200 100 300 400 500 600 700 hiking on foot and skis dog sledging a ve ra g e n u m b e r o f vi si td a ys 0 500 1000 1500 2000 0 500 250 750 1000 1250 1500 j f m a m j j a s o n d snowmobile other activities fig. 3 monthly numbers of reported recreational activities in svalbard. “other activities” include excursions in rubber boats, kayaking and shorter hikes. the numbers are the averages for the years 2003–07. data source: governor of svalbard (2006, 2007, unpubl. data). n o . p la n n e d la n d in g s b y co a st c ru is e s h ip s 0 200 400 600 800 j f m a m j j a s o n d fig. 4 monthly numbers of planned landings by cruise ships in svalbard in 2007. data source: association of arctic expedition cruise operators (unpubl. data). 1000 0 500 1500 pink-footed goose (sassendalen) barnacle goose (sassendalen) brent goose (lurøya) m e tr e s (85) (40) (6) (38)(75) fig. 5 escape flight distance (white boxes) and alert distance (grey boxes) in response to an approaching person for three goose species in svalbard during the pre-nesting period (no alert distances were recorded for brent geese). the plot shows the median values (solid horizontal lines), the 25 and 75% quartiles (boxes) and ranges (dotted lines). see text for statistics. the sample sizes are shown in parentheses above each box. disturbance of breeding geese j. madsen et al. polar research 28 2009 376–389 © 2009 the authors382 two islets in kongsfjorden (storholmen and prins heinrichøya), nor were there differences in the response of male and female birds (females, storholmen, 28.7 � 2.2 m, n = 53; females, prins heinrichøya, 23.6 � 3.4 m, n = 25; student’s t-test, t = -1.3, df = 44.8, p = 0.20; males, storholmen, 29.2 � 2.3 m, n = 51; males, prins heinrichøya, 23.3 � 3.7 m, n = 25; student’s t-test, t = -1.4, df = 74, p = 0.16). therefore, data from the two islets were pooled, and the site was termed “kongsfjorden” in further analyses. both the breeding site and sex had a significant effect on the efd (glm, type iii, sum of squares: site, f = 28.7, df = 3, 1, p = 0.0001; sex, f = 31.7, df = 3, 1, p = 0.0001). the average efds for the various species and sites are presented in fig. 6. for males, there was a significant difference between the sites (anova, f = 92.96, df = 3, 103, p = 0.0001), with pink-footed goose males in sassendalen fleeing the nest site at significantly greater distance than males from any other site, or than males from the other two species, which did not differ in escape distances. for females, differences were not only significant among sites, but also within the same species at different sites (anova, f = 7.51, df = 3, 124, p = 0.0001; fig. 6). the average escape distances were greatest for pink-footed goose females in sassendalen and barnacle goose females in kongsfjorden. the shortest escape distances were found for brent goose females on lurøya (fig. 6). for the barnacle geese in kongsfjorden, there was a highly significant and positive correlation in the efd among sexes (r2 = 0.80, n = 76, p = 0.0001), meaning that, in general, individuals in a pair behaved similarly towards an approaching person. females and males in the most tolerant and most shy pair departed their nests at exactly the same distance, giving similar ranges in efd (both sexes: 1–80 m). by contrast, for pink-footed geese in sassendalen, the variation in efd varied considerably (females, 8–100 m; males, 35–200 m; fig. 6), and no correlation among sexes was found (r2 = 0.001, n = 11, p = 0.95). there was no correlation among sexes for the barnacle geese breeding on hornøya and lurøya (all p > 0.3), and variation in the efd was also less at these sites (fig. 6). fleeing distances. fleeing distances are available for brent geese on lurøya, pink-footed geese in sassendalen and barnacle geese on hornøya (fig. 7). there were significant differences in the fleeing distances among the three species/sites (anova, females, f = 29.17, df = 2, 28, p = 0.0001; males, f = 110.41, df = 2, 27, p = 0.0001). pink-footed geese in sassendalen had the longest fleeing distances, departing their nests and flying several hundred metres away when a person approached the nest (fig. 7). at hornøya, barnacle goose females followed their males after they departed the nest, giving similar fleeing distances for both sexes (fig. 7). predation rate. a summary of the consequences for goose eggs after the provoked nest approaches is presented in table 1. sample sizes are largest for kongsfjorden, where only 4% of the nests (4 of 79) were predated by gulls within the first day after the provocation (table 1). for pink-footed geese in sassendalen this was rather different, as almost 35% of the nests (16 of 46) included in the analyses lost their complete clutch after a similar approach (table 1). for brent geese on lurøya and barnacle geese on hornøya, samples are limited, but all pairs included in the study returned after they had departed their nests, and no eggs were observed to have been lost to predators (table 1). for pink-footed geese in sassendalen, there were no significant differences in efds for females among the predation categories no eggs lost vs. egg loss (student’s t-test, t = 0.51, df = 15, p = 0.62; table 1). data on males are too limited for statistical tests, and small and skewed sample sizes also limit statistical tests for the other sites. 200 150 0 100 50 250 m e tr e s 100 75 0 50 25 125 pink-footed goose (sassendalen) barnacle goose (hornøya) barnacle goose (hornøya) brent goose (lurøya) (a) (b) a b b b bc ab c a fig. 6 escape flight distances in response to an approaching person for geese nesting at different sites in svalbard. (a) males and (b) females are shown separately in box plots with medians (solid horizontal lines), 25 and 75% quartiles (boxes) and ranges (dotted lines). the same letters above each box indicate no significant differences between sites, whereas different letters indicate that the differences are significant (anova, duncan grouping: males, f = 92.96, df = 3, 103, p = 0.0001; females, f = 7.51, df = 3, 124, p = 0.0001). disturbance of breeding geesej. madsen et al. polar research 28 2009 376–389 © 2009 the authors 383 disturbance effects: brood-rearing period limited data exist for the brood-rearing period. because of insufficient data, records on the efds and fleeing distances of families towards an approaching person were pooled in three species-based categories: pink-footed goose records from daudmannsodden, gipsdalen and sassendalen; brent goose records from hornøya, kalvøya and lurøya in tusenøyane; and barnacle goose records from sassendalen. a visual inspection of the data did not show signs of site-specific differences. significant differences were found among species in efd (anova, f = 67.81, df = 2, 13, p = 0.0001), with the longest distances being recorded for pink-footed geese (average 1717 m, n = 6), followed by brent geese (average 620 m, n = 5) and barnacle geese (average 330 m, n = 5) (fig. 8). pink-footed geese also had the longest average fleeing distance (pink-footed geese, 1502 m, n = 5; barnacle geese, 500 m, n = 1; brent geese, 340 m, n = 5), but no significant differences were found among species (barnacle goose excluded, student’s t-test, t = -2.32, df = 4.08, p = 0.08), although small sample sizes limit the value of the statistical tests. discussion measures of human activity the travel statistics on human activity have limited value for studying the potential effects of disturbance, as they do not include activities other than tourism, and therefore do not reflect the total load of human activity 1500 1000 0 500 2000 m e tr e s pink-footed goose (sassendalen) barnacle goose (sassendalen) brent goose (lurøya) fig. 8 escape flight distances in response to an approaching person for family groups of the three species of geese at different sites in svalbard. the box plot shows medians (solid horizontal lines), 25 and 75% quartiles (boxes) and ranges (dotted lines). 400 300 0 200 100 500 400 300 0 200 100 500m e tr e s pink-footed goose (sassendalen) barnacle goose (hornøya) brent goose (lurøya) (a) (b) a a b a a b fig. 7 fleeing distances from the nest after the approach of a person for geese nesting at different sites in svalbard. (a) males and (b) females are shown separately in box plots with medians (solid horizontal lines), 25 and 75% quartiles (boxes) and ranges (dotted lines). the same letters above each box indicate no significant differences between sites, whereas different letters indicate that the differences are significant (anova, duncan grouping: males, f = 110.41, df = 2, 27, p = 0.0001; females, f = 29.17, df = 2, 28, p = 0.0001). there were no data available for kongsfjorden. table 1 egg predation in goose nests after provoked nest approaches by a walking person. the average escape flight distances (efds) are presented in metres (� standard error). the sample sizes are given in parentheses. no. of nests with no egg loss no. of nests with partial egg loss no. of nests with complete egg loss sex efd (m) for pairs with no egg loss efd (m) for pairs with egg lossa brent 13 0 0 females 9.1 � 0.6 (13) — (lurøya) males 35.8 � 7.1 (13) — pink-footed goose 30 — 16 females 47.1 � 9.5 (8) 39.4 � 11.3 (9) (sassendalen) males 175.0 � 25.0 (2) 150.0 � 22.4 (5) barnacle goose 6 0 0 females 7.5 � 0.6 (2) — (hornøya) males 31.7 � 2.8 (6) — barnacle goose 75 1 2 females 27.0 � 1.8 (75) 27.0 � 15.6 (3) (kongsfjorden) males 27.3 � 2.0 (73) 27.7 � 15.1 (3) apartial and complete clutch loss combined. disturbance of breeding geese j. madsen et al. polar research 28 2009 376–389 © 2009 the authors384 (vistad et al. 2008). furthermore, the tourism data that are available do not have a geographical resolution that permits accurate estimations of overlaps with goose sites. the only exceptions are the records of cruise landing sites. they show that landings occur all around svalbard, although at highly variable intensities. we do not have data to suggest any relationships between the load of human activity and disturbance effects and impacts. however, at crucial times and places, such as during nesting or on islets during the post-hatching period, our results from the provoked human approaches suggest that just a few visits can potentially severely influence nesting success or gosling survival in cases where families flee to the sea, and have to swim long distances. the seasonal pattern in tourist traffic gives us a picture of potential conflict periods. there may be a potential conflict between snowmobile and dog-sledging activities and the arrival of pre-nesting geese in may; however, we do not have any data that would elucidate this. cruise landings, other boating activities and hiking overlap with the nesting and posthatching periods of geese, including the time when geese are flightless. to better understand the potential temporal and spatial conflicts between human activity and geese, we recommend that more detailed information is collected on the nature and extent of not only tourism, but all human activities that have the potential to impact geese as well as other wildlife in svalbard. escape flight distances behavioural measures such as efds only give an indication that disturbance caused by human activity could have a negative effect, although not necessarily with any fitness consequences (gill et al. 2001; gill 2007). however, in this study we have documented a negative impact, through increased predation rates at nests from which parent geese fled. as data was collected opportunistically over a long time period, in various places and by different observers, the results and interpretations must be treated with some caution, and should primarily be used to suggest guidelines for regulating tourism. nevertheless, the results show that there are significant differences in behavioural reactions towards human disturbance by the three species of geese, and that reactions vary with the timing and the site. pre-nesting. the pre-nesting period, i.e., the period between the arrival of the birds in svalbard and the start of egg-laying, is regarded as a crucial period in the annual cycle of the geese. during this period, they maintain or improve their body condition as a prelude to breeding. in barnacle and pink-footed geese it has been shown that adults, in particular females, improve their body condition during this period (hübner 2006; fox unpubl. data). during the pre-nesting period, a large proportion of the tundra and its vegetation may be snow-covered or frozen, inhibiting pink-footed geese from feeding on the subterranean rhizomes and roots upon which they rely (fox et al. 2007). hence, the geese may be constrained in food availability, and displacement from feeding patches as a result of disturbance may reduce food intake, with negative repercussions for the subsequent breeding potential. we found that pink-footed geese in sassendalen were very shy, with an average efd of almost 400 m. this is in strong contrast to observations from another valley in svalbard, adventdalen, where the average efd of flocks of pre-nesting pink-footed geese approached by a walking person has been registered at 35 m (n = 5; fox unpubl. data). the difference may result from habituation to human traffic in adventdalen, close to the longyearbyen settlement, which is in most cases restricted to road traffic. road traffic is directional, frequent and hence relatively predictable, whereas people walking on the tundra are infrequent and move relatively randomly, and hence may be perceived as a higher risk. in situations with greater snow cover in adventdalen, geese feeding along roadsides and close to buildings have been observed with efds of less than 10 m (eide, pers. obs.). this represents an extreme case, and probably indicates that the birds are under a strong pressure to find food, and therefore make compromises between avoiding predation and feeding. the observations show that efds are highly variable between sites and snow conditions, and that the nature of human activity as well as the physiological state of the birds may influence their responses. nesting. in barnacle and brent geese we found that males and females had short efds and flew or ran short distances upon disturbance. in several instances we observed the geese attacking avian predators during our stay in the territory, and that they returned to the nest as soon as we had left the territory. the observed difference in efds of barnacle geese between kongsfjorden and hornøya is probably related to the state of the incubating females. on hornøya, where data were collected in late june and early july, the geese were close to hatching their clutches, when geese become more sedentary (kongsfjorden was visited earlier, in mid-june). in contrast to the males of other species, male pink-footed geese were flushed at a long distance from the human intruder, and often flew to a position out of view of the nest. female pink-footed geese stayed on the nest with an efd similar to females of the other two goose species; disturbance of breeding geesej. madsen et al. polar research 28 2009 376–389 © 2009 the authors 385 however, female pink-footed geese also flew away, often landing in positions out of view of the nest. the consequence of the intrusion was manifest in a high rate of predation of eggs by glaucous gulls or skuas, even though we carefully covered the eggs with down. we noticed that when we entered the goose colonies, gulls and skuas often followed. the reaction by the pink-footed geese indicates a strong fear of humans, which may be attributed to the regulated hunting of the species, with an open season in svalbard, mainland norway and denmark. the inference of the limited losses of eggs as a result of human intrusion in colonies of brent and barnacle geese does not mean that the nesting geese are not vulnerable to disturbance. intruding humans, perhaps landing on a nesting island in a group and then spreading out over the island, and who are possibly unaware of the presence of nesting geese and the importance of covering exposed nests, are more likely to increase the risk of predation by gulls and skuas. brood rearing. our data sets for all three species are small; nevertheless, significant interspecific differences were found. families of pink-footed geese showed an escape response at a distance of almost 2 km from the approaching human, whereas the efds of families of barnacle and brent geese were shorter. brent and barnacle goose families always feed in close proximity to open water, where they can seek protection in case of disturbance. in contrast, pink-footed geese often feed far inland, and will not seek protection on lakes; instead, they run inland, towards the river (in sassendalen; fox et al. 2007; fox et al. 2009) or retreat to the sea. in gipsdalen it was twice observed that families feeding at the foot of a steep slope ran uphill to hide at an elevation of 300–400 m a.s.l. (madsen, pers. obs.). their behaviour is possibly an adaptation to the fact that they can defend themselves against arctic foxes, whereas the extreme reaction towards humans can only be interpreted as indicating a strong fear of humans. families of barnacle geese, the most tolerant of the three species, will run to the refuge lake in the case of a disturbance, and will then stay on the lake. in ny-ålesund, and more recently in adventdalen, barnacle goose families have habituated to human activities, and now occur close to human settlements and traffic. in ny-ålesund, it is not humans, but the occurrence of arctic foxes, which can predate heavily on the goslings, that is the main factor constraining their flexibility in site use in the settlement (loonen et al. 1998). as a result of their highly localized distribution in svalbard, i.e., in tusenøyane, moffen and a few other areas, brent geese are highly vulnerable to disturbance, especially during the brood-rearing period, when cruise boats can reach the islands. during the nesting period, dense drift ice prevents access by boats in most years, although in some years they can get there in june (madsen et al. 1998). people walking on the small islands may potentially cause the families to leave and swim across to other islands, or even north to edgeøya. in tusenøyane, food resources are very limited (madsen et al. 1989; madsen et al. 1998), and a displacement of the geese may have repercussions for the growth, and, ultimately, survival of goslings. moult. during the flightless period, geese are highly restricted in their site use and stay in close proximity to open water (madsen & mortensen 1987). we have very limited information about efds in non-breeding moulting geese, but from observations from east greenland it is known that pink-footed geese are extremely wary: human intrusion in lake moulting areas can cause geese to run across the tundra and abandon the moulting site (madsen et al. 1984). barnacle geese were more relaxed and remained on the moulting areas (madsen et al. 1984). although quantitative data are lacking, it seems likely that because the geese are flightless, a disturbance that will cause the geese to depart from the refuge and run across the tundra will greatly increase the risk of predation by arctic foxes. post-breeding. during the late summer, when nonbreeding geese, goslings and parents have gained powers of flight, and before heavy snowfall sets in, they are highly flexible and can find food over vast expanses of svalbard that were not exploitable earlier in the season on account of snow cover or the behavioural constraints of the geese. we have no quantitative information about their reactions to disturbance during this period, but the geese must be regarded as less vulnerable during this period. the hunting season for pink-footed geese starts on 20 august, and this may constitute a local disturbance; however, the number of hunters in svalbard is low and the hunting is very localized, and cannot be regarded as a critical source of disturbance in the wider svalbard area. management implications currently, probably none of the three goose species are critically threatened by human activity in svalbard. however, this paper highlights some important issues, which may result in guidelines for human activities in the context of the potentially increasing disturbances of geese resulting from heavier and more widespread traffic at various times of the season. disturbance of breeding geese j. madsen et al. polar research 28 2009 376–389 © 2009 the authors386 pre-nesting. there is a potential conflict between snowmobile activities and pre-nesting geese that congregate in areas such as vårsolbukta and adventdalen. because there is little information about disturbance effects during pre-nesting, we recommend that a study address this particular potential conflict. nesting. nesting birds are vulnerable to disturbance. the major colonies of barnacle geese (on islands along the west coast) and brent geese (on moffen) are refuges with no human access during the nesting period. pink-footed geese appear to be particularly vulnerable because of their long escape flight and fleeing distances, which exposes nests to predation. as these geese mostly breed in colonies on islands and in inland tundra areas, guidelines for human traffic are easily suggested. detailed maps of known goose breeding colonies should be made available to visitors. guidelines should include information on what consequences disturbance could have, as well as advice on appropriate behaviour. people should not walk closer than 1 km from the dense nesting areas. for pink-footed geese, verification of predictions of suitable nesting areas by wisz et al. (2008) and jensen et al. (2008) should be confirmed by more ground-truthing fieldwork in the most visited spots. in this connection, the importance of having good geographical resolution on all human traffic must be emphasized (also see the evaluations made by vistad et al. 2008). we have limited knowledge of the distribution of human traffic in the most visited areas around isfjorden (management area 10), where several breeding colonies are located. traffic in this area has increased, and more people are visiting the interior of isfjorden (e.g., sassendalen) on their own initiative (eide & madsen, pers. obs.). setting up a campsite, in sassendalen, for example, with hikes radiating out from the camp, could have severe negative impacts on nest success for geese in this area if the appropriate precautions are not taken. post-hatching. goose families are highly vulnerable to hiking in the brood-rearing areas; brent and barnacle geese are confined to staying close to open water, and can potentially be prevented from foraging for a long time on account of the presence of humans. again, families of pink-footed geese are particularly vulnerable because of their extremely long efds. hikers traversing the valley floor of sassendalen may be unaware of geese fleeing at long distances in front of them, and people walking through the valley can unintentionally drive large numbers of geese all the way down the river, resulting in lost feeding time and potentially increased predation risk. in high-density brood-rearing areas, hiking routes should be regulated to avoid mass disturbance. moult. non-breeding moulting geese are highly sensitive to disturbance, and precautions should be made to avoid landings and hiking in high-density moulting sites. at present, there is no good svalbard-wide overview of existing moulting grounds, but known major moulting sites should be marked on maps made available to visitors, along with the appropriate advice. post-breeding. the period before departure seems to be relatively undisturbed, and geese appear to be less vulnerable on account of their regained ability of flight and the widespread availability of food resources. no particular precautions appear necessary for the time being. acknowledgements this work was carried out under a contract from svalbard’s environmental protection fund. the fieldwork in tusenøyane was part of a national environmental research institute (neri) sudy, in collaboration with the norwegian polar institute (npi). banding of geese and opportunistic observations of geese in daudmannsøyra, gipsdalen, sassendalen, recherchefjorden and dunderbukta were also undertaken by neri researchers. studies in sassendalen were a collaborative effort by neri, the norwegian institute for nature research (nina) and the netherlands institute of ecology, under the eu fifth framework fragility of arctic goose habitat: impacts of land use, conservation and elevated temperatures (fragile) project (contract evk2-2001-00235). studies in kongsfjorden were undertaken by nina, funded by the research council of norway under terrestrisk økologisk forskningsprogram på svalbard, otherwise known as the terrøk programme. we especially thank ingunn holøymoen, erle frantzen, espen bergersen, christian glahder, tony fox, marcel klaassen, geir wing gabrielsen and thomas bregnballe for their support in collecting the data in the field. we thank torkild tveraa for constructive discussions, and an anonymous reviewer for valuable comments on the manuscript. the governor of svalbard and the npi provided important logistical assistance. references alsos i.g., elvebakk a. & gabrielsen g.w. 1998. vegetation exploitation by barnacle geese branta leucopsis during incubation on svalbard. polar research 17, 1–14. andersen m. & aars j. 2008. short-term behavioural response of polar bears (ursus maritimus) to snowmobile disturbance. polar biology 31, 501–507. disturbance of breeding geesej. madsen et al. polar research 28 2009 376–389 © 2009 the authors 387 beale c.m. & monaghan p. 2004. behavioural responses to human disturbance: a matter of choice? animal behaviour 68, 1065–1069. blumstein d.t., anthony l.l., harcourt r. & ross g. 2003. testing a key assumption of wildlife buffer zones: is flight initiation distance a species-specific trait? biological conservation 110, 97–100. bregnballe t. & madsen j. 1990. post-hatching behaviour of light-bellied brent geese branta bernicla hrota. wildfowl 41, 27–34. clausen p., madsen j., percival s.m., anderson g.q.a., koffijberg k., mehlum f. & vangeluwe d. 1999. light-bellied brent goose branta bernicla hrota: svalbard. in j. madsen et al. (eds.): goose populations of the western palearctic. a review of status and distribution. wetlands international publication 48. pp. 312–327. rønde, denmark: national environmental research institute. drent r., black j.m. & prop j. 1998. barnacle geese branta leucopsis on nordenskiöldkysten, western spitsbergen—in thirty years from colonisation to saturation. in f. mehlum et al. (eds.): research on arctic geese. proceedings of the svalbard goose symposium, oslo, norway, 23–26 september 1997. norsk polarinstitutt skrifter 200. pp. 105–114. oslo: norwegian polar institute. fox a.d., bergersen e., tombre i.m. & madsen j. 2007. minimal intra-seasonal dietary overlap of barnacle and pink-footed geese on their breeding grounds in svalbard. polar biology 30, 759–768. fox a.d., eide n.e., bergersen e. & madsen j. 2009. resource partitioning in sympatric arctic-breeding geese: summer habitat use, spatial and dietary overlap of barnacle and pink-footed geese in svalbard. ibis 151, 122–123. fox a.d., francis i.s. & bergersen e. 2006. diet and habitat use of svalbard pink-footed geese during arrival and pre-breeding periods in adventdalen. ardea 94, 691–699. fox a.d. & madsen j. 1997. behavioural and distributional effects of hunting disturbance on waterbirds in europe: implications for refuge design. journal of applied ecology 34, 1–13. frid a. & dill l. 2002. human-caused disturbance stimuli as a form of predation risk. conservation ecology 6(1), article no. 11. gill j. a. 2007. approaches to measuring the effects of human disturbance on birds. ibis 149, 9–14. gill j.a., norris k. & sutherland w.j. 2001. why behavioural responses may not reflect the population consequences of human disturbance. biological conservation 97, 265–268. glahder c.m., fox a.d., hübner c.e., madsen j. & tombre i.m. 2006. pre-nesting site use of satellite transmitter tagged svalbard pink-footed geese anser brachyrhynchus. ardea 94, 679–690. glahder c.m., fox a.d., o’connell m., jespersen m. & madsen j. 2007. eastward moult migration of non-breeding pink-footed geese (anser brachyrhynchus) in svalbard. polar research 26, 31–36. governor of svalbard 2006. turisme og friluftsliv på svalbard. utvikling, politiske føringer, rammebetingelser, utfordringer og strategier. (tourism and outdoor recreational activities in svalbard. development, political guidelines, regulating framework, challenges and strategies.) sysselmannens rapportserie 1/2006. longyearbyen: office of the governor of svalbard. governor of svalbard 2007. reiselivsstatistikk for svalbard 2007. (travel statistics for svalbard 2007.) longyearbyen: office of the governor of svalbard. griffin l.r. & mackley e.r. 2004. wwt svalbard barnacle goose project report 2003–2004. slimbridge, uk: wildfowl & wetlands trust. hübner c.e. 2006. the importance of pre-breeding areas for the arctic barnacle goose branta leucopsis. ardea 94, 701–713. jensen r.a., madsen j., o’connell m., wisz m.s. & mehlum f. 2008. prediction of the distribution of arcticnesting pink-footed geese (anser brachyrhynchus) under a warmer climate scenario. global change biology 14, 1–10. jepsen j.u., eide n.e., prestrud p. & jacobsen l.b. 2002. the importance of prey distribution in habitat use by arctic foxes (alopex lagopus). canadian journal of zoology 80, 418–429. johnson c.j., boyce m.s., case r.l., cluff h.d., gau r.j., gunn a. & mulders r. 2005. cumulative effects of human developments on arctic wildlife. wildlife monographs 160. lawrence, ks: the wildlife society. kålås j.a., viken å. & bakken t. (eds.) 2006. 2006 norwegian red list. trondheim: the norwegian biodiversity information centre. laursen k., kahlert j. & frikke j. 2005. factors affecting escape distance of staging waterbirds. wildlife biology 11, 13–19. loonen m.j.j.e., oosterbeek k. & drent r.h. 1997. variation in growth and adult size: evidence for density dependence. ardea 85, 177–192. loonen m.j.j.e., tombre i.m. & mehlum f. 1998. the development of an arctic barnacle goose colony: interaction between density and predation. in f. mehlum et al. (eds.): research on arctic geese. proceedings of the svalbard goose symposium, oslo, norway, 23–26 september 1997. norsk polarinstitutt skrifter 200. pp. 67–79. oslo: norwegian polar institute. madsen j. 1984. study of the possible impact of oil exploration on goose populations in jameson land, east greenland. a progress report. in f. mehlum & m. ogilvie (eds.): current research on artic geese. proceedings of a symposium at voksenåsen, oslo, 24–26 october 1983. norsk polarinstitutt skrifter 181. pp. 141-151. oslo: norwegian polar institute. madsen j. 1985. impact of disturbance on field utilization of pink-footed geese in west jutland, denmark. biological conservation 33, 53–63. madsen j. 1998. experimental refuges for migratory waterfowl in danish wetlands. i. baseline assessment of disturbance of breeding geese j. madsen et al. polar research 28 2009 376–389 © 2009 the authors388 the disturbance effects of recreational activities. journal of applied ecology 35, 386–397. madsen j., boertmann d. & mortensen c.e. 1984. gæssene i jameson land. resultater af undersøgelser 1982–84. (geese in jameson land. results of investigations in 1982–84.) copenhagen: grønlands fiskeri-og miljøundersøgelser. madsen j., bregnballe t., frikke j. & kristensen j.b. 1998. correlates of predator abundance with snow and ice conditions and their role in determining timing of nesting and breeding success in svalbard light-bellied brent geese branta bernicla hrota. in f. mehlum et al. (eds.): research on arctic geese. proceedings of the svalbard goose symposium, oslo, norway, 23–26 september 1997. norsk polarinstitutt skrifter 200. pp. 221–234. oslo: norwegian polar institute. madsen j., bregnballe t. & hastrup a. 1992. impact of the arctic fox alopex lagopus on nesting success of geese in southeast svalbard, 1989. polar research 11, 35–39. madsen j., bregnballe t. & mehlum f. 1989. study of the breeding ecology and behaviour of the svalbard population of light-bellied brent goose branta bernicla hrota. polar research 7, 1–21. madsen j., kuijken e., meire p., cottaar f., haitjema t., nicolaisen p.i., bønes t. & mehlum f. 1999. pink-footed goose anser brachyrhynchus: svalbard. in j. madsen et al. (eds.): goose populations of the western palearctic. a review of status and distribution. wetlands international publication 48. pp. 82–93. rønde, denmark: national environmental research institute. madsen j. & mortensen c.e. 1987. habitat exploitation and interspecific competition of moulting geese in east greenland. ibis 129, 25–44. madsen j., tamstorf m.p., klaassen m., eide n., glahder c.m., riget f.f., nyegaard h. & cottaar f. 2007. effects of snow cover on the timing and success of reproduction in high-arctic pink-footed geese anser brachyrhynchus. polar biology 30, 1363–1372. mehlum f. 1998. areas in svalbard important for geese during the pre-breeding, breeding and post-breeding periods. in f. mehlum et al. (eds.): research on arctic geese. proceedings of the svalbard goose symposium, oslo, norway, 23–26 september 1997. norsk polarinstitutt skrifter 200. pp. 41–55. oslo: norwegian polar institute. overrein ø. 2002. virkninger av motorferdsel på fauna og vegetasjon: kunnskapsstatus med relevans for svalbard. (effects of motorized traffic on fauna and vegetation: knowledge relevant to svalbard.) rapportserie 119. tromsø: norwegian polar institute. owen m. & black j.m. 1999. barnacle goose branta leucopsis: svalbard. in j. madsen et al. (eds.): goose populations of the western palearctic. a review of status and distribution. wetlands international publication 48. pp. 258–268. rønde, denmark: national environmental research institute. r development core team 2008. r: a language and environment for statistical computing. vienna: r foundation for statistical computing. sander g., hanssen-bauer i., bjørge a. & prestrud p. 2005. miljøovervåking av svalbard og jan mayen—mosj. en dokumentasjon av systemet og den første vurderingen av miljøstatus. (environmental monitoring of svalbard and jan mayen—mosj. documentation and first evaluation of environmental status.) rapportserie 123. tromsø: norwegian polar institute. sas institute 2004. sas/stat user’s guide. version 9. cary, nc: sas institute. tombre i. m., black j.m. & loonen m.j.j.e. 1998. critical components in the dynamics of a barnacle goose colony: a sensitivity analysis. in f. mehlum et al. (eds.): research on arctic geese. proceedings of the svalbard goose symposium, oslo, norway, 23–26 september 1997. norsk polarinstitutt skrifter 200. pp. 81–89. oslo: norwegian polar institute. tombre i.m. & erikstad k.e. 1996. an experimental study of incubation effort in high-arctic barnacle geese. journal of animal ecology 65, 325–331. tombre i.m., mehlum f. & loonen m.j.j.e. 1998. the kongsfjorden colony of barnacle geese: nest distribution and the use of breeding islands 1980–1997. in f. mehlum et al. (eds.): research on arctic geese. proceedings of the svalbard goose symposium, oslo, norway, 23–26 september 1997. norsk polarinstitutt skrifter 200. pp. 57–65. oslo: norwegian polar institute. vistad o.i., eide n.e., hagen d., erikstad l. & landa a. 2008. environmental impacts from traffic and tourism in the arctic—a literature review and state-of-knowledge focusing on svalbard. nina report 316. lillehammer: norwegian institute for nature research. wisz m.s., tamstorf m.p., madsen j. & jespersen m. 2008. where might the western svalbard tundra be vulnerable to pink-footed goose (anser brachyrhynchus) population expansion? clues from species distribution models. diversity and distributions 14, 26–37. wolfe s.a., griffith b. & wolfe c.a.g. 2000. response of reindeer and caribou to human activities. polar research 19, 63–73. disturbance of breeding geesej. madsen et al. polar research 28 2009 376–389 © 2009 the authors 389 what determines the distribution of seabirds at sea? editors: kjell einar erikstad, robert t . barrett and fridtjof mehlum preface the rationale behind the nordic workshop, 'what determines the distribution of seabirds at sea?', held in skibotn, near t r o m s ~ . 17-21 october 1988, was the initiation of a new pelagic scabird rcscarch programme at tromsca museum. wc felt a need to gathcr experts within oceanography, fishcrics biology and marine ornithology to discuss how to best organize such rcscarch in relation to thc available resources. it was attcndcd by 24 students and scientists from 7 countries. including those specially invited from the usa, canada and scotland. 24 papers were presented, of which 12 make up this volume. seabirds spend most of their time at sea. yet the vast majority of seabird research has becn (and still is) limited to the short, hcctic breeding season when the seabirds come ashore and are easily accessible. only during thc last few decades have seabirds been recognizcd as an integral part of the marine ecosystem and multidisciplinary programmes have becn initiated to investigate the mcchanisms and processes which regulate thc patterns of their distribution at sea. knowledge of the pelagic ecology of seabirds away from the colonies is critical for the understanding of their population dynamics and hence also for a sensiblc managcmcnt of the various species. after the reviews presented by the non-scandinavian guests, the majority of the contributions t o the workshop addressed various processes which arc thought to be critical causal mcchanisms affecting the distribution of seabirds at sea i n a scandinavian contcxt. a central topic rcpcatedly presented was the distribution of birds in relation to that of their prey, but underlying the discussions were thc unccrtainties of how well they werc corrclatcd and to what extent physical processes such as wind, currents, ice-cover, fronts, etc. determine the movements of both birds and their prey. these have been the subjects of several wcll documented papers, yet it was agreed that a lot more data are needed at a variety of spatial and temporal scales before seabird movements in relation to physical and biological features can be fully understood. such studies will necessitate a continual close cooperation between occanographers, fisheries biologists and marine ornithologists. the workshop was organized by tromscb muscum, and we are very grateful to the nordic collegiates for ecology, wildlife research and marine biology (nordisk kollegium for 0kologi. nordisk kollegium for viltforskning and nordisk kollcgium for marinbiologi), and the university of tromscb for financing the workshop. tromsca & oslo, february 1990 kjell einar erikstad', robert t. barrett" & fridtjof mchlum" * norwegian institute for nature research, troms0 museum, univ. of tromsca, n-9000 tromsca, norway * * norwegian polar research institute, p.o. box 158, n-1330 oslo lufthavn, norway surface temperatures of the barents sea lars mid'ttun midttun, l. 1990: surface temperatures of the barents sea. polar research 8 , 11-16. temperature conditions in the barents sea are determined by the quality and quantity of the inflowing atlantic water from the west and by processes taking part in the barents sea itself, in particular as a consequence of winter cooling and ice formation. the field of inflow to the barents sea during the period 1977-1987 has been studied. the surface winter temperatures within the barents sea vary in parallel with variations in the deeper layers of the inflowing water masses, whereas the surface temperatures in summer have a different variation pattern which is most likely dependent on the summer heating process. lars midttun, fiskeridirektoratets havforskningsinstitutt, p . 0. box i870 nordnes, n-5024 bergen, norway; may 1989 (revised september 1989). the temperature conditions in the barents sea are determined by the quality and quantity of the water masses flowing into the sea from the west, but also by processes taking place in the sea itself. the inflowing, relatively warm water is strongly cooled during the winter and the surface gradually freezes. the northern barents sea is therefore ice covered in winter. as a consequence of cooling and ice formation, the water becomes denser, sinks and gradually mixes deeper in the water column. in shallower areas, this vertical con vection may extend to the bottom, and results in the formation of bottom currents transporting cold and dense water out of the barents sea. during the summer, the sea ice in the north gradually melts resulting in the formation of a low salinity surface layer, which slowly warms up. this process leads to the formation of surface currents transporting the light surface water out of the barents sea. the main pattern in the surface current system is illustrated in fig. 1 (from loeng 1988a). the boundary between the cold arctic water masses in the north and the warmer subarc tic water masses of the southern barents sea is called the polar front. the western field of inflow all stations were comprised of aanderaa meters at various depths between the surface and the seabed. the experiment was run for nearly two months in the autumn, and the average observed currents are presented in fig. 2 (from blindheim 1989). near the norwegian coast the coastal cur rent flows eastwards at an average speed of c. 25cm/sec (c. 0.5 knot). in the central field, between 72"n and 73"n, atlantic water also flows eastwards at velocities near 10 cm/sec. the total water transport through the section into the barents sea was, in this period, as much as 3 sv (i.e. 3 x 106m3/sec). outflow from the barents sea consists of 1) surface water in the upper 100m layer near bj@rn@ya and 2) dense bottom water on the north ern slope of the bj@rn@ya channel. the total westward transport is 1.2 sv, of which 0.8 sv is dense bottom water. thus, more water flows into the barents sea than out through this section. the surplus, c. 2 sv, must consequently be transported out of the barents sea through the straits between svalbard. frans josef land and novaya zemlya. midttun (1985) has shown outflowing dense bottom water between frans josef land and novaya zemlya, but a quantification of this bottom current has, as yet, not been possible. temperature and salinity in the section fugl the inflow of water masses from the west has regularly been observed in a section between fugl@ya in troms and bj@rn@ya (fig. 1). in 1978, current observations were made using 9 anchored buoy stations along this section line. @ya-bj&n@ya have, since-1977, been recorded regularly six times a year. the mean temperatures of the 50-200m layer in the central part of the section (71°30'n-73"30'n) have been calculated for each of these six periods (fig. 3). as we have 12 lars midttun 80 7 8 7 1 11, 7 2 7c 68 / /' i i i i ! 4 fig. 1. surface current in the barents sea. solid arrows: atlantic water current, dashed arrows: arctic water current, dotted arrows: coast water currents. the polar front is indicated by shading. location of the fuglplya-bj0mplya section is shown (after loeng 1988). seen, the temperature in this layer has a normal yearly variation of c. 1.3"c. the temperature is highest in september-october and lowest in march-april. however, the large standard devi ations indicate variations from year to year (i.e. anomalies, apc), and these are presented in fig. 4. periodic variations evidently occur over a num ber of years, with a 'cold' period in 1977-1982, followed by a warm period until 1985. the war mest year was 1983. parallel fluctuations have been recorded in sections further east in the barents sea (midttun 1989) and in the kola sec tion observed by the ussr and where the obser vation series were started as early as 1900. observations from this russian section show that a normal based on the years 1977-1987 is slightly l a 1 north 7$" 7 3 " 7 2" 71" 70" bjbrnbya f u g l b y a i \ i .----e fig. 2. currents through the fugl@ya-bj@rn@ya section in september-october 1978. velocity in cm/sec. observation points are indicated (+). solid lines: current towards east, dashed lines: current towards west (after blindheim 1989). 6.51 60 50 c l 5 lo\ i \ i i "1 1 0 0.5 y 0: 4 ' 0 5 l o t 77 ' 78 ' 79 ' 80 81 ' 8 2 i 83 i 8 l i 85 i 86 ' 87 -15' r fig. 4. temperature anomalies at 50-200 m in 1977-1987 along the fugl~ya-bj@rn@ya section. 14 lars midttun fig. 5 . maximum winter ice coverage in thc barents sea 1979 1986. lower than that based on measurements made between 1920-1980. it is thus likely that our 1977 1987 'normal' is lower than the long-term normal. the variability of temperature and salinity off the coast of northern norway has previously been compared with those of the kola section data set by midttun (1969). winter surface-temperatures as mentioned earlier, the northern arctic part of the barents sea freezes in winter and the ice cover is normally most extensive in march. c. 2 m of ice form each winter in the northernmost area of the barents sea (nansen 1906; midttun 1985). the norwegian meteorological institute (dnmi) prepares weekly maps of the ice border in the barents sea and the maximum ice coverage for the years 1979-1986 is presented in fig. 5. the variations are greatest in the central and eastern parts of the barents sea. ice coverage was largest in 1979 and smallest in 1983 and 1984. with basis in observations collected during research vessel surveys carried out in february march 1977-1987, it has been possible to con struct charts of surface temperatures for all the years. with some interpolations it has also been fig. 6 . mean winter surface temperatures of the barents sea 1977-1987. grid net indicated. standard stations each year and to calculate mean values for all the standard stations (fig. 6). the surface temperature at ice covered stations has been estimated to be -1.8"c. by taking the mean value of all the 92 standard station values each year as a yearly temperature index, the year-to-year variation can be presented l . o j , , , i , 1 i i i i 1 77 78 79 80 81 82 83 84 85 86 87 fig. 7. variations of winter surface temperatures of the barents y e a r possible to prepare matrices for temperatures at sea 1977-1987 fig. 8 . winter temperatures and ice border in the barents sea in the cold winter of 1979. grid net indicated. surface temperatures of the barents sea 15 (fig. 7). the temperature indices vary over a range of more than 2°c. the coldest year was again 1979 and the warmest was 1983. the vari ations in winter surface temperatures through the years 1977-1987 resemble the variations found at deeper layers in the fuglaya-b j ~ r n a y a section (cf. fig. 4). the surface temperature conditions of the cold est year (1979) are presented in fig. 8. the indi cated ice border is the average location observed in march 1979 as published by dnmi. fig. 9. mean summer surface temperatures of the barents sea 1967-1987. grid net indicated. summer surface-temperatures an international fish survey with several research vessels from norway, the ussr and the uk (until 1976) has been carried out every year since 1967 between 20 august and 10 september. obser vations collected during these surveys form the basis of the present summer temperature analysis (fig. 9). the data sets are standardized in the y e a r fig. 10. variations of summer surface temperatures of the barents sea 1967-1987 16 lars midttun same way as the winter data sets. the summer grid net covers a somewhat larger part of the barents sea, but at a lower density in the eastern part of the area. temperature indices have also been calculated for the years 1967-1987 (fig. 10). temperatures vary over a range of 2”c, but the variation pattern is apparently quite different from the variation in the winter surface tem perature (cf. fig. 7). most striking is the dif ference for 1983, a year of maximum winter temperatures but extremely low summer tem peratures. the most likely conclusion is that surface tem peratures in summer are determined by local con ditions where the incoming heat radiation plays the most important role, while the winter tem peratures are related to the inflow of warm atlantic water from the west. biological effects the effect of oceanographic conditions on distri bution and population dynamics of commercial fish stocks in the barents sea was the subject of a symposium held in murmansk in 1986 (loeng 1987). other relevant studies are saetersdal i% loeng (1987) and loeng (1988b). in short, these analyses conclude that the high temperature in the 50-200 m water column of the kola section, which is representative for inflowing water masses, generally favours an easterly distri bution and better growth in the fish stocks of the barents sea. strong year classes of cod, haddock and herring are more often born in ‘warm’ years than in ‘cold’. acknowledgements. t h e author wishes to thank karen gjert sen, ingrid byrkjedal, ellen sophie lauvis, 0ivind astensen and harald kismul for valuable help with the preparation of this paper. references blindheim, j . 1989: cascading of barents sea bottom water into the norwegian sea. rapp. p.-u. rtun. cons. int. explor. mer 188, 49-58. loeng, h. (ed.) 1987: the effect of oceanographic conditions on distribution and population dynamic of commercial fish stocks in the barents sea. proceedings of the third souiet norwegian symposium murmansk, 2 6 2 8 may 1986. institute of marine research, bergen. loeng, h . 1988a: current conditions in the barents sea. arctic pilot 7, 150-159. loeng, h. 1988b: the influence of climate on biological con ditions in the barents sea. nafo scr doc. 88/83. midttun, l. 1969: variability of temperature and salinity at some localities off the coast of norway. progress in oceano graphy 5 , 41-54. midttun, l. 1985: formation of dense bottom water in the barents sea. deep-sea research 32(10), 1233-1241. midttun, l. 1989: climatic fluctuations in the barents sea. rapp. p.-u. rtun. cons. int. explor. mer 188, 23-35, nansen, f. 1906: northern waters: captain roald amundsen’s oceanographic observations in the arctic seas in 1901. viten skabs-selskapets skrifter i , matematisk-naturu. klasse. 1906 (3). 145 pp. saetersdal, g. & loeng, h. 1987: ecological adaptation of reproduction in northeast arctic cod. fish. res. 5 , 253-270. no job name b o o k r e v i e w por_124 310 review of plants at the margin. ecological limits and climate change, by r.m.m. crawford (2008). cambridge: cambridge university press. 478 pp. isbn 978-0-521-62309-4. professor crawford does it again! it was a great privilege to be asked to review professor crawford’s latest book, plants at the margin, and i did so with immense pleasure. it is a hefty tome, a full 478 pages, but is easy to read and richly illustrated with figures, tables and maps, as well as many photographs from crawford’s own expeditions. crawford draws on his own extensive field experience, and his love of the arctic clearly shines through, with examples from svalbard, greenland, iceland, ellesmere island, siberia and northern scandinavia. many other books about plant ecology focus on plant life in well-established, stable-state vegetation types. crawford’s book gives a new and refreshing slant to plant ecology by examining situations where plants are at the margins of their existence. marginal areas are, by their nature, dynamic ecosystems, and this book explores the various difficulties and challenges for plants to survive in changing and harsh conditions. crawford pulls together his own studies and those undertaken by an impressive list of refereed authors (there are 27 pages of up-to-date references to scientific publications). these are based on ecological observations and studies of experimental plant ecology and ecophysiology, in both the field and laboratory, together with studies from the fields of biogeography, demography, reproductive biology and genetics. plants at the limits of their distribution are very likely to be affected by climate change. this is a timely work, now that the general public has started asking the big question, “so what is the effect of climate change likely to be?” this book points the reader towards finding out some of the answers. the common features of marginal areas and the challenges they produce for plants are discussed first in the book, before going into detail about different types of marginal habitats. part i focuses on the nature of marginal areas and their effects on biodiversity. part ii examines plant function in marginal areas: how they overcome resource limitations and short growing seasons in order to effectively reproduce. part iii discusses selected case histories of different marginal habitats. case histories include examples from the arctic, at high altitudes, in coastal margins and at the water’s edge, and include problems of flooding and aeration, and the special case of woody plants. in addition, human influence has also been discussed, including settlement, agricultural and coastal issues, soil impoverishment and impact on wetlands. the book concludes with chapters on signs of change, vegetation responses, adaptations to climate change, fragility versus stability and diversity of ecosystems, conservation and regeneration, and future prospects. plants at the margin is a book that is suitable for students and researchers, and for others interested in both marginal habitats and the impact of climate change. i would highly recommend it as an undergraduate text book. there is also an electronic version, with all the figures and illustrations from the book made available for lecturers’ presentations, which will help to inspire and motivate students. professor crawford writes: “numerous illustrations have been included as a reminder of the place of plants in their habitats and that whatever may be learnt from the application of sophisticated methods of investigation it is the existence of the plant in its environment that has prompted our initial curiosity” (p. xiv). well done professor crawford—another good book for us to learn from and enjoy! correspondence elisabeth cooper, department of biology, university of tromsø, no-9037 tromsø, norway. e-mail: elisabeth.cooper@uit.no polar research 28 2009 310 © 2009 the author, journal compilation © 2009 blackwell publishing ltd310 mailto:cooper@uit.no book review book review polaris: the chief scientist’s recollections of the american north pole expedition, 1871–73, translated and edited by william barr, calgary, canada: university of calgary press, 2016, 643 pp., 44.95 usd (hardback), isbn 978-1-55238-875-4. this important translation places german scientist emil bessels’ own account of the ill-fated american polaris north pole expedition in the english language for the first time. with the publication of chauncey loomis’ seminal weird and tragic shores: the story of charles francis hall, explorer in 1971, bessels assumed a status as the primary villain in an arctic drama that resulted in the still-mysterious death of expedition leader hall and the separate and miraculous retreats and rescues of the polaris crew. prior to hall’s death and the dissolution of the crew, the expedition had successfully blitzed northwards through melville bay, smith sound, kane basin and into robeson channel, to a point far more northerly than any ship before. hall, an almost mystical arctic vagabond who, when required, could put on ‘impressive display[s] of chutzpah’ (pp. xix–xx), was in early september of 1871 less than 475 miles from the north pole, a stunning achievement and one that left him in excellent position to make a brilliant strike for the pole the following spring. yet, as bessels notes in his fascinating account, once hall refused to force the polaris’ ice-master budington further north: ‘fortune, which had accompanied us thus far, became ill-disposed to us and never smiled on us again’ (p. 149). polaris, the book, is a beautifully produced volume, with excellent maps at the fore, with reproductions of 46 illustrations that accompanied bessels’ german original scattered throughout, and with the editor’s skilful scholarly impedimenta. all these add to the successful translation of a critical primary source into english. somewhat surprisingly, especially as secondary sources of the expedition portray bessels as something of a dull martinet, bessels’ account itself is an excellent read, in almost every segment full of detail without being pedantic. from the details of the ship and its provisioning, to inuit anthropology and scientific recording, the secreting of alcohol stores on a publically identified ‘temperance ship’, all are rendered with both detail and, unexpectedly, humour. excellent descriptions are provided of st. johns and the western settlements of greenland and the inhabitants of these places that even today lie on the fringe of civilization, yet are central to the examination of global climate change. the account is also a very early and comprehensive destruction of the latitudes, the geography and the ‘open polar sea’ claimed by another american arctic explorer, isaac israel hayes, and here bessels’ conclusions could not be more direct: ‘where hayes claims to have sighted his open polar sea, there is land…’ (p. 209), and, undoing 20 years of accumulating dogma, much of it due to hayes’ mismeasurements and enthusiasms, ‘we viewed this open water not as an open polar sea, whose existence was dictated by thermal conditions, but as a local phenomenon provoked by winds and currents’ (p. 254). bessels’ observations of the variety of geologic uplift and subsidence along the west coast of greenland are also fascinating and point to a new generation of scientists who increasingly viewed the planet and the life upon it as inherently unstable. these, combined with the detailed accounts of the logistical issues with scientific data collection in extreme environments, make the volume even more valuable. the descriptions of the ship and the sounds that snapped through it during an arctic storm are first rate. bessels refreshingly makes scientific observations without simultaneously stretching them to accommodate some geographic theory. there is also a wealth of scattered and rewarding vignettes, such as archaeological notes on previous exploring camps and shipwrecks such as the hayes observatory and sonntag’s disturbed grave site, to say nothing of the shakespeare-quoting whaler polar research, 2017 vol. 36, 1310805 https://doi.org/10.1080/17518369.2017.1310805 http://www.tandfonline.com captain adams. appendix 4 furthermore contains biographical sketches that are particularly well written and detailed with excellent research. despite the amount of attention that has been fixed upon bessels as the chief suspect in hall’s death, bessels’ narration of hall’s sudden incapacitation and lingering death occupies only three pages, offering nothing in the way of personal insight into bessels’ thoughts or actions during these critical days. given that hall had just returned in apparent splendid health and optimism from a difficult two-week sledge journey and that tyson pronounced him amazingly fit, his extreme and extremely sudden illness after drinking a single cup of coffee remains as mysterious as ever. as the translator–editor points out, one has to read between the lines and any implied criticism. as for a motive bessels might have had, the editor makes a brief but persuasive case, based upon materials recently uncovered by the arctic historian russell potter, of an unrequited affair between bessels and the young sculptress vinnie ream. ream liked to cultivate older influential men and her apparent attentions to the famous hall could have tipped bessels into a fit of jealously that led to him administering lethal doses of arsenic to hall when he had the opportunity. if one adds romantic jealousy to bessels’ ambition for polar glory, as well as bessels’ natural academic distaste for hall’s distinctly un-academic personality, and then combines these with other highly suspicious facts (bessels not allowing budington to sample the medicine he was administering to hall; hall recovering somewhat when not being treated by bessels), then one perhaps gains a comprehensive foundation for a case to answer in the often alleged murder of charles francis hall. taken together, this finely edited translation will become a standard acquisition of all english-language libraries with polar research and reference collections. reference loomis c. 1971. weird and tragic shores: the story of charles francis hall, explorer. new york: random house. p. j. capelotti division of social sciences, abington college, pennsylvania state university, abington, pa, usa pjc12@psu.edu © 2017 p. j. capelotti https://doi.org/10.1080/17518369.2017.1310805 2 book review https://doi.org/10.1080/17518369.2017.1310805 http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1310805&domain=pdf book review reference special issue in connection with professor john 0. krog’s 65th birthday professor, dr. philos. john krog john krog was born in meldal, norway on the 29th of august, 1918. he graduated (cand. real.) at the university of oslo in 1949, with zoology as his major subject, and in 1964 obtained his doctorate at the same university. john krog worked as a biology teacher at oslo teachers’ college in 1950 before spending four years working as a physiologist with professor lawrence irving in anchorage, alaska, under the exchange visitor’s program, u.s. public health service. from 1954 until 1964 he worked at the institute for experimental medical research, ullevll hospital, oslo, first as research fellow in circulatory physiology and from 1962 as associate professor. he was visiting research professor at the department of physiology and biophysics, university of kentucky medical school, lexington, kentucky, u.s.a. from 1964 t o 1965 and was appointed professor and chairman of the institute of zoophysiology, university of oslo, in 1965. 220 professor john krog during leave from these positions, john krog extended his qualifications through short stays in other research institutions. he studied circulatory physiology and polarographic oxygen determination under dr. h. c. bazett and professor h . montgomery. university of pennsylvania; microcirculation under dr. benjamin zweifach, university of boston. and professor e. bloch, western reserve university; circulatory physiological methods and problems connected with adaptability to cold under professor otto edholm. national institute for medical research, london; and problems concerning vasodilatation due to cold at the university of gothenburg. john krog has participated in several scientific expeditions. he spent six months in panama making physiological studies on counter-current principles (1956-57). in finnmark, norway, he studied acclimatization to cold in lapps and fishermen (1957-58). he went with alpha helix to the bering sea (1968). was the leader of an expedition to greenland to study blood circulation of the eskimos (1968), and made two expeditions to enare, finland, for studies on adjustments to cold in the skolt lapps (1969-70). john krog is a member of the editorial board of acta microcirculatoriu; he is a member of the national committee for biophysics, the constitutional committee for the international biophysical union, t h e scientific committee on oceanographic research, and is a representative of the interna tional union of physiological sciences. he has membership in the scandinavian association of physiologists, the scandinavian society for clinical physiology, the european microcirculatory society, and the aerospace medical association; he is a fellow of the american association for the advancement of science and of the arctic institute of north america. during his career, john krog has attended a number of international congresses and several symposia in the capacitv of guest speaker. he has also given lectures on topics of popular science. john krog has published about 80 scientific papers, mainly on circulatory physiology and adaptation to cold. his interest in the biology of arctic animals was strongly stimulated when he worked with lawrence irving in alaska. he later experimented with seals and reindeer. in addition to his research, john krog promoted zoophysiology, extending the possibilities for graduate studies in this subject a t the university of oslo. most university positions in zoophysiology in norway are held by former students from his institute. graduate students and scientists in the field of experimental medicine have also benefited from his encouragement and advice. ola b. reite list of publications krog. j 1953: notes on the birds of amchitka island. alaska. the condor 55. 299. irving. l . & krog. j . 1954: body temperatures of arctic and subarctic birds and mammals. j . appl. physiol. 6 . 667. krog. j . 1954: improved needle thermocouple for subcutaneous and intramuscular temperature measurements in animals and man rei,. s c i . /n.rrrum. 25. 799 krog. j . & simmet. r . 1924: an attachment for the low-power binocular microscope facilitating obsemations at controlled temperatures. trans am. .vicroscop. soc. lxxxx. 4. krog. j . 1954: storing of food items in the winter nest of the alaskan ground squirrel. cirellus undularu. 1. mammal. 35. 586. krog. j . 1954: the influence of seasonal environmental changes upon the metabolism. lethal temperature and rate of heart beat of gammarw limnaeu (smith) taken from an alaskan lake. biol. bull 107. 397. irving. l . & krog j . 1955: temperature of skin in the arctic as a regulator of heat. 1. appl. physiol. 7 , 1. krog. j . 1955: notes on temperature measurements indicative of special organization i n arctic and subarctic plants for utilization of radiated heat from the sun. physiol. plant. 8 . r36. krog. j . 1956: an inexpensive temperature controlled room for clinical and physiological investigations. j . oslo city h o s p . 6. 76. krog. j . 1956: modern electrical temperaturc measurements and some of their applications in experimental physiology and medicine. . i . oslo clry hosp. 6. 117. storm-mathiesen. a . & krog. j . 1956: skin resistance measure ments: a comparative study of the results obtained by using the regelsberger and kaiser apparatus. j . oslo city h o s p . 6. 77. krog. j , 1956: thermistor hypodermic needle for subcutaneous temperature measurements. r e v . sci. instrum. 27, 408. irving. l. & krog. j . 1956: temperature during the develop ment of birds in arctic nests. physiol. zool. xxix, no 3 . erikson. h . & krog. j . 1956: the critical temperature in naked man. acra physiol. scand. 37. 35. scholander, p. f . , lange andersen, k. & krog, j . 1957: critical temperature in lapps. j . appl. physiol. 10, 231. krog. j . & scholander. p . f. 1957: countercurrent vascular heat exchange. with special reference to the arteriovenous bundles in sloths. acta physio/. s c a d . 42, suppl. 145. scholander. p. f. & krog, j . 1957: countercurrent heat exchange and vascular bundles in sloths. 1. a p p l . physiol. 10. 40s. ola b . reite 221 lund, i., johansen, k., krog, j. & birkeland, s . 1958: the change in vascular resistance of the dog’s brain on perfusion with cold blood and modifying effect of coz and trimsta plancamphor-sulphonate (arfonad). acta anaesth. scand. 2 , 149. krog, j . & johansen, k. 1959: construction and characteristics of tefloncovered polarographic electrode for intravascular oxygen determination. reu. sci. instrum. 30. 108. birkeland. s . . vogt. a.. krog. j. & semb, c. 1959: renal circulatory occlusion and local cooling. j . appl. physiol. 14, 227. johansen. k. & krog, j. 1959: diurnal body temperature vari ations and hibernation in the birch-mouse, sicista betulina. a m . 1. physiol. 196. 1200. birkeland. s . . krog, j . , vogt, a . & semb, c. 1959: renal function following ischemia under renal hypothermia. j. appl. physiol. 14, 227. krog. j . 1959: notes on rectal temperature variations in dogs during nembutal anaesthesia. acta physiol. scand. 45. 308. johansen, k. & krog. j . 1959: peripheral circulatory response to submersion asphyxia in the duck. acta physiol. scand. 46. 194. johansen. k. & krog. j . 1959: polarographic determination of intravascular oxygen tension in vivo. acta physiol. scand. 46. 228. kristiansen. k., krog, j. & lund, i. 1959: experiences with selective cooling of the brain. acta chir. scand. suppl. 253, 151. krog, j . & johansen. k. 1960: the relation between muscular blood flow and oxygen tension as measured polarographi cally. acta chir. scand. suppl. 253, 162. semb, c., krog. j . & johansen, k. 1960: renal metabolism and blood flow during local hypothermia. studied by means of renal perfusion in situ. acta chir. scand. suppl. 253, 196. krog, j . , folkow. b., fox, r. h. & lange andersen, k . 1960: hand circulation in the cold of lapps and north norwegian fishermen. 1. appl. physiol. 15, 654. andersen. p.. johansen. k. & krog, j. 1960: electroencepha logram during arousal from hibernation in the birch-mouse. a m . j. physiol. 199. 535. aukland. k. & krog. j . 1960: renal oxygen tension. nature 188. 671. folkow, b . , fox. r . h., krog, j . , odelram, h. & thoren, 0. 1960: an analysis of the vascular response to intense cooling. acta physiol. scand. suppl. 175. 1. aukland, k. & krog, j . 1961: influence of various factors on urine oxygen tension in the dog. acta physiol. scand. 5 2 , 350. kristiansen. k. & krog. j . 1962: electromagnetic studies on the blood flow through the carotid system in man. neurology 12. 1. krog. j . & kristiansen, b. 1962: a new filter unit for extra corporeal circulation. j. oslo city hosp. 1 2 , 108. ingebrigtsen, r . . krog, j . & leraand. s . 1962: velocity and flow of blood in the femoral artery proximal to an experi mental arterio-venous fistula. acra chir. scand. 124. 45. krog. j . 1962: effects of cervical sympathetic stimulation on cerebral circulation. excerpts medica, international congress series, no. 48. krog, j . . leraand. s . . kristiansen, b. & kristiansen. k. 1962: a servooperated perfusion unit for selective cooling of the brain. j. oslo city hosp. 12, 238. krog, j . 1963: electrical measurement of body temperature. acta anaesth. scand. suppl. x i . 99. folkow, b . , fox. r . h.. krog. j., odelram. h. & thoren, 0. 1963: studies on the reactions of the cutaneous vessels to cold exposure. acta physiol. scand. 58, 342. krog. j . & amundsen, b . 1963: a simple instrument for measurement of onset of claudication symptoms in patients suffering from atherosclerosis of the lower limbs. j. oslo city hosp. 13. 31. ingebrigtsen, r . , krog. j. & leraand: s . 1963: circulation distal to experimental arterio-venous fistulas of the extrem ities. acta chir. scand. 125, 308. fange, r . . krog, j . & reite. 0. b . 1963: blood flow in the avian salt gland studied by polarographic oxygen electrodes. acta phvsiol. scand. 58. 40. fange. r . & krog. j . 1963: inability of the kidney of the hagfish to secrete phenol red. nature 199, no. 4894. 713. krog, j. & reite, 0. b. 1963: the circulatory effect of bra dykinin in birds. acta physiol. scand. 59, suppl. 213. reite. 0. b.. krog. j. & johansen. k. 1963: notes on the development of bradycardia during submersion of the duck. nature 200, 684. krog, j . 1963: oxygen supply in aquatic f o r m . pergamon press. oxford. krog, j . 1963: the use of polarographic oxygen tension measurements for estimation of rapid changes in regional blood flow. j . oslo city hosp. 13, 65. krog, j. 1963: the effect of cervical sympathetic stimulation on cerebral blood flow in birds. j . oslo city hosp. 13, 201. krog. j. 1963: the effect of cervical sympathetic stimulation on cerebral blood flow in the rabbit. 1. oslo c i g hosp. 13. 185. irving, l., west, g. c. & krog. j . 1964: changes in water content of arctic plants during winter. science in alaska, 37. johansen, k., krog, j. &reite, 0. b. 1964: autonomicnervous influence on the heart of the hypothermic hibernator. annales acad. scient. fenn. series a . iv biologica 71. 17. carlson, l. d. & krog, j . 1965: effects of subpressures applied to the lower part of the human body. pror. of the x x l f l international congress of physiological sciences, 73. murray. r . . krog. j . , carlson, l. & rowers, j . 1965: lower body negative pressure as a provocative test for the circulatory system. the physiologisl8, 238. krog, j . . cohn. j. & shannon. r . 1965: the effect of water immersion upon the cardio-pulmonary functions in the goose. proc. of the american physiological society fall meeting, los angeles. reite. 0. b . , krog, j . & carlson, l. d. 1965: influence of noradrenaline on vascular resistance in the intact perfused ears of coldadapted and warmadapted rabbits. proc. of rhe international symposium on enviromental physiology. wyndham, c . h., morrison, j. f., krog. j. & carlson. l. d . 1965: standardization of methods for estimating body tol erance to cold. proc. of the international symposium on enviromental physiology. japan. murray, r. h., krog, j . , carlson, l. & bowers. j a . 1966: cumulative effects of venesection and negative pressure applied to the lower body. rep. from aerospuce medicine. 37, 1. smith, r . e. & krog, j. 1966: a p e l t i a effect heat exchanger appropriate for temperature regulatory studies in small ani mals. arctic aeromed. lab. 6. krog. j . 1966: physiological adaption to arctic living in the nomad lapps. physical activity in health and disease. 262. krog, j. & smith, r. e. 1967: miniature peltier effect heat exchanger for extracorporeal circulation. j. appl. physiol. 22. 2 . murray, r. h., krog, j . , carlson, l. d. &bowers, j. a. 1967: 222 professor john krog cumulative effects of venesection and lower body negative pressure. aerospace medicine 38(3). 242-241. cohn, j . e . , krog, j . & shannon, r . 1968: cardiopulmonary responses to head immersion in domestic geese. 1. a p p l . physiol. 25. 1. krog. j 1968: forslag ti1 metodikk for bed0mmelse av den perifere sirkulasjonstilpassing ti1 kuldc hos mennesker nor disk medicin 79. 414 krog, j . . alvik. m . 8; lund-larsen. k. 1969: investigations of the circulatory effects of submersion of the hand in ice w t e r in the finnish lapps. the skolts. federation proceedings. vol. 78. 3. krog. j . . reite. 0. b. & fjellheim. p. 1969: vasomotor responses in the growing antlers of the reindeer. rangifer tarandus nature 223. 99-100. iversen. j . a . & krog. j 1972. body temperatures and resting metabolic rates i n small petrels. norw 1. 2001. 20. 141-144. iversen. 1. a . & krog. j . 1972: body temperatures in active and resting charadriiforme birds (murres. puffins and auklets) at diffcrent ambient temperatures. norw. 1. zool. 20. 145 146. iversen. j a . & krog. j . 1973: heat production and body surface area in seals and sea otters. .yorw. j. 2001. 21. 51 54. krog. j . 1975: manniskans anpassning till kallt klimat. finska lnkaresallskapetr handlingar a r g . 135. band 119. 11-13. krog. j . . wika. m.. lund-larsen. t . , nordfjell. j . & myrnes. i . 1976: spitsbergen reindeer. rangifer rarandus planrhvn chus vrolik. morphology. fat storage and organ weights in the late winter seabun. norw. 1. zool. 24. 407417. ringherg. t . jacohsen. e . . ryg. m. & krog. j . 1977: seasonal changcs in levels of growth hormone. somatomedin and thg roxine in free-ranging. semi-domesticated norwegian rein deer (rarigifer raratidus rarandus (l,)). comp. biochem. phvsiol. @a. 122-126. krog, j . 1979: vascular studies by means of external application of negative pressure. j. oslo cify hosp. 2 9 , 119-121. krog. j . . zachariassen, k. e . , larsen, b. & smidsr@d, 0. 1979: thermal buffering i n afro-alpine plants due to nucleat ing agent induced water freezing. nature 282, 300-301. wika, m., krog. j . & bjarghov. r . 1979: thermoregulation in newborn reindeer calf. i n : abstracts from x v i scand. congress of phvsio/ogy and pharmacoiogy . oulu. paschc. a . & krog. j.1980: heart rate in resting seals on land and in water. comp. biochem. physiol. 67a. 11-83. krog. j . . wika. m. & savalov. p. 1980: the development of the foetus of the norwegian reindeer. pp. 306310 in rei mers. e.. gaare. e. & skjenneberg. s . (eds.): proc. 2nd in[. reindeericaribou s y m p . , rbros, n o w a y . direktoratet for vilt og ferskvannsfisk. trondheim. wika. m. & krog. j . 1980: antler 'disposable vascular b e d . pp. 422-424 in reiners, e.. gaare, e. & skjenneberg, s . (eds.): proc. 2nd lnt. reindeerlcaribou s y m p . . r@ros, nor way. direktoratet for vilt og ferskvannstisk, trondheim. wika. m. & krog. j. 1980: thermoregulation and brown adi pose tissue in the newborn reindeer calf. pp. 425-431 in reimers, e . . gaare. e . & skjenneberg, s . (eds.): proc. 2nd int. reindeerlcaribou s y m p . , rsros, n o w a y . direktoratet for vilt og ferskvannsfisk. trondheim wika. m. 1980: on growth of reindeer antlers. pp. 416421 in reimers. e . . gaare. e . & skjenneberg, s . (eds.): proc. 2nd lnr. reindeerjcaribou s y m p . . r ~ r o s . n o w a y . direktoratet for vilt og ferskvannsfisk. trondheim. wika, m . & krog, j . 1980: the vascular bed of reindeer antler. proc. iups 001. x i v , x x x v i l l int. congress, budapest. the influence of grazing by hypogastrura viatica (insecta: collembola) on microbial activity in decomdosing kelp on spitsbergen a per sveum sveum, p. 1986: the influence of grazing by hypogasfrura viatica (insecta: collembola) on microbial activity in decomposing kelp on spitsbergen. polar research 5 n.s.. 71 77. the influence of three different grazing levels (5-20 ind.) by hypogastrura viarica (collembola) on micro bial activity in a spitsbergen kelp laminaria has been evaluated during a 10 day laboratoly experiment under oxic conditions. respiration has been measured by infra-red gas analysis in the form of c o ,-emissions. the total and metabolically active fungal and bacterial biomass has been estimated by direct microscopical counts and epifluorescence techniques. despite the results of other similar experiments, a n increase in microbial numbers and biomass was recorded following the introduction of grazing. grazing increases the mean respiration between 0.6 to 1.4 times. a corresponding increase in the microbial biomasses was also recorded. although a trend towards decreased mean bacterial cell size was found, the fungi were more influenced by grazing than the bacteria. bacteria constituted the predominant part of the microbial biomass in all the experimental vessels. the results indicate that collembola plays an important functional role by regulating the microbial activity, probably by nutrient mobilization. per sveum. sintef, division of applied chemistry. applied biology group, n-7034 trondheim-nth. norway; march i986 (revbedjanuary 1987). meiofauna has normally a limited direct influen ce on the turnover of organic matter in ecological systems (anderson et al. 1981; petersen & lux ton 1982). only a small fraction of the total c 0 2 respired, and thus carbon mineralized, is meta bolized directly by the faunal component of the ecosystem. in many systems, however, the meioand microfauna are known to enhance the minerali zatiodnutrient cycling and carbon mineraliza tion through their consumption of microbial biomass, i.e. fungal hyphae and bacteria (e.g. johannes 1965). as anderson (1975) pointed out, the study of the interaction between micro fauna and microflora is one of the most intract able problems of ecology. there have been few studies dealing with the microbial ecology of decomposing kelp heaps to date. as griffith & stenton-dozey (1981) noted, little is known about the fate of stranded kelp. the aim of this study was to evaluate the influ ence of one type of heterotrophic interaction, i.e. grazing by collembola o n the decomposing dynamics. at the same time more general effects on decomposition and microbial activity by micro grazers can also be evaluated. the present ex periments were carried out as a part of a study of the ecology of seaweed heaps on spitsbergen. this substudy has been very much influenced by similar investigations where comparable experi mental designs and background philosophies have been employed, (see hanlon & anderson (1979) and andren & schniirer (1985)). stranded kelp is initially rich both in energy a n d nutrients, and microbial activity is supported very well. as the seaweed loses its initial structu ral support through water loss and decomposi tion, a more or less solid layer of variable depth is formed, which is associated with a very limited exchange of gas. this enhances the formation of anoxic conditions dominated by anaerobic microbial activity. 72 koop et al. (l982b) estimated the total amount of carbon mineralized by microbes to be about 70%. however, less than 4% of the nitrogen wrecked in macrophytal biomass is recorded as leaching. this implies a very high degree of microbial immobilization of nitrogen although ammonia is the principal end product of micro bial decomposition both in aquatic and terrestri al habitats (cf. fenchel & blackburn 1979) and might be lost to the atmosphere under airy condi tions. sveum (in prep.) found very high fractions of the total microbial biomasses in kelp beds o n spitsbergen sea shores to be metabolically in active. seaweed heaps on spitsbergen differ from those found i n central and southern norway because of their lower biological activity, and consequently they have a heterogeneous and more aerobic gas composition than the anaerobic temperate varieties (sveum, in prep.). only one species of collembola, hvpogasfrura viatica was found in any number in the seaweed heaps (sveum, i n prep.), and this species was selected as the microbial grazer for the experiment. h j p o gastrura has earlier been found to graze on fungal biomass (addison 1977). koop et al. (1982a) reported that kelp (i.e. eklomia maxima) is primarily decomposed by bacterial activity rather than by fungi. the spitsbergen kelp beds were composed of two more or less distinct layers; an upper one where aerobic conditions predominated and a lower more or less anoxic layer. the kelp studied and reported in this paper is of the first type. here h . viaticadominated among the invertebra tes. the protozoa have not yet been studied in these kelp beds. material a n d methods experimental design decomposing seaweed (laminaria) was collect ed at kvadehuken in the outer part of kongs fjorden on the western coast of spitsbergen. the decomposing seaweed had been on the shoreline for approximately 12 months. the experimental period of 20 days was divi ded into two periods of 10 days each. the de composing samples of seaweed were incubated at 5 o c in gas tight, 100 ml glass vessels. then the seaweed was extracted to remove the meiofauna and was later supplied with a n equal amount of demineralized water to compensate for the water lost by evaporation during extraction. the vessels were allowed to acclimatize for 48 hours at the incubation temperature before they were closed. incubation was carried out in a thermo incubator, in total darkness. a total of 40 experimental vessels was used. after 10 days, 3 different levels of grazing by the collembola species hvpogastrura viatica were supplied to 30 of the incubation vessels (i.e. 10 replicates of each grazing level). analytical techniques the coz content of the vessels was measured every second day. to avoid hypertension and anaerobiosis in the vessels, fresh outdoor air was supplied by complete aeration. the co, content of the gas samples was measured with an infrared gas analyzer (siemens ultramat i ) , modified for septum injection and calibrated with gas mix tures of known coz concentration. the total co, emission for each vessel was calculated by the numerical integration of the cumulative co, curve. as the respiration rate of hypogastrura viatica was not measured in the present study, the rate given by aunaas et al. (1983) for onychyums groenlandicus from a nearby site on spitsbergen, was applied. conversion from oxygen consumption to car bon dioxide production was done using r q = 0.8 (andrtn & schniirer 1985), and from microlitre t o microgram carbon by the general gas law. the collembolan respiration for each vessel was calculated as equal to the integrated animal respiration, assuming a linear growth curve from the number added at day 10 to the number present at day 20. the fresh weight of the collembola was 3.33 times the dry weight (pers son 1983). at the end of the experimental period, bacteri al counts and fungal measurements by epi fluorescence microscopy were carried out on the content of each vessel. the total bacterial number was determined by staining with acridine orange (ao) (trolldenier 1972) and by staining the metabolically active bacteria with fluorescein diacetate (fda) (lundgren 1981). the total of 73 fungal hyphae was measured after staining with methylene blue (jones & mollison 1948), while the length of the metabolically active fraction was measured with fda ( s o d e r s t r ~ m 1977). the intersection method described by olsson (1950) was used in both cases. results and discussion extensive studies of the feeding habits of h . viu tica have not yet been camed out. however, microscopical examination of a few guts of the species obtained from the kelp beds on spits bergen showed that fungal hyphae were part of its content. it has been shown earlier that col lembola consume hyphae (christiansen 1964; petersen & luxton 1982). h . viatica is a typical surface-living species in this habitat. according to bodvarson (1970) surface-living species have a greater tendency to be fungal feeding than the strictly soil-living species. h . viatica occurs in several very different habitats on spitsbergen. it is not known how far the predominant diet varies according to local adaptations within various habitats. the total respiration of the vessel communities for the first 10 days, with and without animals (days 11-20) is given in table 1. the estimated collembola respiration is also given in the same table. there is an increase in the total community respiration in the grazed vessels. the increase is linear with the rise in grazing pressure (r = 0.97, p <0.01). the differences between all combina tions of grazed treatments are found to be statisti cally significant. no significance is found be tween the treatment groups in the ungrazed ini tial period. the estimated grazing by collembola does not account for the increased respiration activity, as it only comprises 0.3% t o 0.7% of the total respiration. the total increase ranges from 64% to 145% compared to the control. bacteria constitute the predominant part of the microbial biomass in all the vessels. this is con sistent with the results of koop et al. (1982a). the abundance and masses of biota in the incubation vessels are given in tables 2,3 and 4. although the total length of fungal hyphae does not increase linearly with grazing pressure (i.e. hyphae are longer in an ungrazed state than at a low grazing pressure), a linear increase is found in the metabolically active fraction (r = 0.97, p<o.oi). the increased metabolical activity of fungal hyphae is probably the result of the increased availability of nutrients due to grazing by the collembola. the relative fraction of metabolically active hyphae in the vessel with grazers (41 -45%) is significantly different from the ungrazed (27%) (x2 = 4.97, p<o.oi), although no significant increase is found with increasing grazing pressure (r = 0.52, n.s.). grazing by amoebae may be a possible ex planation of this unexpected ratio. andren and schniirer (1985) pointed out that amoebae feed by puncturing the hyphal cell walls and sucking out the cytoplasma. the grazed hyphae will still be measured as total hyphae. if we assume that the effect of collembola grazing on bacterial cells indirectly stimulates the amoeba1 popula tion by increasing bacterial cell growth, the lack of increase in metabolically active fungal hyphal length might be an indirect effect of collembola table 1. total respiration, microbial respiration and estimated collembola respiration in the different groups of incubation vessels, after 10 and 20 days, respectively. measured or estimated parameter no. collembola _ _ _ _ _ _ _ ~ ~ ~ ~ 0 5 10 20 measured total resp. day 1-10 l 2 4 f 0. i4 i .47 f 0.12 1.52 f0.14 l.34+ 0.14 measured total resp. day i 1-20 1 . 1 1 f0.09 1.69 k 0.22 2.28 ? 0.21 2.72k0.32 estimated collembola respiration 0 0.005 0.01 1 0.019 74 grazing. the correlation between respiration in days 1 1 to 20 and the total microbial biomass at the termination of the experiment is positive but not statistically significant (r = 0.60, n.s.). a complete correlation was found between grazing level ( r = 1.00, p<o.oi) and respiration in the grazing level, and respiration in the grazing period and the final active fungal length ( r = 1.oo,p<0.01). the correlation between the total number of bacteria and grazing pressure is significant (v = 0.82, p < 0.05). however, the corresponding value for bacterial dry mass and thus carbon is lower ( r = 0.66) and is not significant. this re sults from the relative increase in smaller cells (fig. 1). the correlation between the metabolically 1 2 3 4 5 6 7 8 9 1 0 size q r w p a t ~ i./-; ’ , , ;7 ~ , .. i 8 1 2 3 4 5 6 7 8 9 0 size group fig. i size and shape distribution of bacteria in the incubation vessels at experimental termination. a. 0 collembola added. b. 5 collernbola added. c. 10 col lembola added. d. 20 collembola added. size group 1-5 are cocci of increasing cell size, while size group active bacterial fraction and the grazing pressure is higher than for the total number (r = 0.97, p <0.01), but the correlation between grazing pressure and the active cells is not significant. in the case of fungal hyphae, the relative fraction of metabolically active cells has increased signifi cantly ( x z = 47.37, p < 0.001). the increase in the number of collembola within the experimental period is linear to the number added at day 1 i (r = 1.00, p<o.ool). at the end of the experiment all stages of collem bola specimens were found, showing that repro duction had occured also in the later part of the experimental period. the increase in the number of collembola within the experimental period is linear to the number within any of the vessels below the ‘carrying capacity’ of the available food source. though andren & schniirer (1985) are among those who have reported reduced biomasses in both fungi and bacteria as a result of microbial grazing, the same pattern was not recorded in the present experiment. on the contrary there was an increase both in numbers and biomasses. the biomass increase is lower than the corresponding increase in numbers and length, respectively. an increased mineralization of macro-nutri ents due to the increased grazing pressure of the collembola seems to give a cell growth beyond the consumption of the collembola at the popu lation levels established here. the grazing effect of h . viatica can probably not be explained by exclusive feeding on micro bial cells. the growth response of the microbial biomass might be due not only to the mineraliza tion of microbially bound nutrients by grazing. the presence of a high microbial biomass might stimulate the general consumption of kelp which is rich in nutrient. ulber (1983) found that f. jimetaria was feeding on living plant roots only when infested by fungi to a certain degree. the effect of the microfauna grazing indicates that the growth rate of the microflora is regulated by the availability of nutrients. this is in accord ance with the results of koop et al. (1982b), who found a very high degree of microbial immobili zation of macro-nutrients in the kelp debris. the apparent reduction in the size of bacteria in the ‘grazed’ vessels (fig. 1) indicates that h . 6-1 i are rods of increasingcell size(cf. ramsay 1983). viatica is able to select longer bacteria as food 75 items. another explanation may be a relative increase in the bacterial species with a rapid adaptation to an improved nutrient supply, and at same time a smaller cell size. as no taxonomic survey of the bacteria present in the experimental vessels has been carried out, nothing is actually known about the growth characteristics of the bacterial species involved. in addition to a pos sible selective feeding on bacteria above a certain size, accidental ingestion of smaller cells together with selected bacteria and fungal hyphae will certainly occur. amy & morita (1983) demonstra table 2. length of fungal hyphae (total and metabolically active), with dry mass and carbon content calculated. measured or estimated parameter no. collembola 0 5 10 20 total hyphal length (m) 420 f 63 3 7 5 f 4 1 462 f 44 451 f 4 6 mg dry mass 0.1 i 0.09 0.12 0.1 i fda-active hyphae (m) 134f 14 1 6 0 f 14 l 8 2 f i6 2 0 4 5 i9 mg dry mass 0.03 0.04 0.05 0.05 active length (yo) 27.3 44.4 41.7 45.4 table 3. number of bacteria (total number and number of metabolically active cells), with corresponding dry mass and carbon content calculated. measured or estimated parameter no. collembola 0 5 10 20 total number of bacteria no. x lo8 4.26 f 0.63 3.43 f 0.42 4.12 f 0.46 5.12 f 0.63 mg dry mass 29.3 1 12.49 9.45 8.0 fda-active bacteria no. x lo8 mg dry mass number active (yo) 0.68 f 0.08 0.91 fo.10 0.99 f 0.1 1 1.98 f 0.23 4.68 3.31 1.98 4.20 16.6 33.3 25.0 37.5 table 4 . number of specimens of hypogastnrra viatica at the experimental termination (no. gdw-i). measured or estimated parameter no. collembola 0 5 10 20 collembola no. 0 42 k 3.2 8 5 f 7 . 3 149f 13.6 mg dry mass 0 0. i64 0.331 0.580 76 ted that bacterial cells which were rod s h a o e d a m y , p.s. & morita. r.y. 1983: starvation-survival when grown under nutrient-rich conditions beca m e coccoid when grown u n d e r nutrient-deficient conditions. although this tendency is not recog nized in this experiment, their results indicate that changes in size g r o u p distribution may b e a more complex matter than a higher influence of grazing o r nutrient changes. when no changes in t h e mean hyphal diameter were found, this might b e d u e t o a more o r less uniform diameter in t h e hyphae offered to the grazer. andren a n d schniirer (1985) f o u n d reduced microbial biomass t o b e a result of grazing by f. firnetaria. the biomass f o u n d at a n y time in a grazed decomposer system will b e determined by the sum of t h e microbial production a n d grazing u p o n the biomass. t h e microbial production varies between different habitats a n d substrates. as does t h e grazing efficiency of the animals involved. it is thus not unexpected that the stand ing microbial biomass in two very different de composer situations deviates. microbes associa t e d with barley straw decomposition probably inhabit a much more stable environment t h a n those associated with decaying kelp. they might t h u s not b e able t o respond to environmental changes as fast as those in the latter habitat. kelp decomposers, o n the other h a n d , especially those living in the upper exposed layer of t h e kelp heaps, are exposed t o changes that might be rapid: e.g. temperature changes, mixing of kelp d u e to wave exposure. these changes will b e even more pronounced in the arctic than in the temperate parts of the world. as mentioned above, only collembola was considered a s a grazer in this experiment. it might, however, b e assumed that protozoa like amoebae, ciliates a n d flagellate species contri bute t o the grazing. acknowledgements. thanks are due to dr. olle and ren, uppsala, and an anonymous referee for their cons tructive comments on an earlier version of this paper. references addison, j.a. 1977: population dynamics, and biology of collembola on truelove lowland. in bliss, l.c. (ed.): truelove lowland, devon island. canada: a high arctic ecosystem. the university of alberta press. patterns of sixteen freshly isolated open-ocean bac teria. appl. environ. microbiol. 45. 1109-i 115. anderson, j.m. 1975: succession, diversity and trophic relationships of some soil animals in decomposing leaf litter. j . anim. ecol. 44.475495. anderson, r.v., coleman, d.c. & cole, c.v. 1981: effects of saprotrophic grazing on net mineraliza tion. in clark, f.e. & rosswall, t. (eds.): terrestrial nitrogen cycles. processes, ecosystem strategies and management impacts. ecological bulletins fstockholm)33.2ol-216. andren. 0. & schniirer, j. 1985: barley straw decom position with varied levels of microbial grazing by folsomta .finmetaria (l.) (collembola, isotomidae). oecologia (berlin) 68.5742. aunaas, t., baust, j.c. & zachariassen, k.-e. 1983: ecophysiological studies on arthropods from spits bergen. polar research i n.s., 235-240. bodvarsson, h. 1970: alimentary studies of seven common soilinhabiting collernbola of southern sweden. entomol. scand. 1.74-80. christiansen, k. 1964: bionomics of collembola. ann. rev. ent. 9, 147-178. fenchel, t. & blackburn, t.h. 1979: bacterial and mineralcycling. academic press, london. griffth, c.l. & stenton-dozey. j . 1981: the fauna and rate of degradation of stranded kelp. est. coast shelf: sci. 12,645453. hanlon, r.d.g. & anderson, j.m. 1979: the effects of collembola grazing on microbial activity in de composing leaf litter. oecologia (berlin) 38.93-100. johannes, r.e. 1965: influence of marine protozoa on nutrient regeneration. limnol. oceanogr. 10, 434442. jones, t.c. & mollison, j.e. 1948: a technique for the quantitative estimation of microorganisms. j . gen. microbial 2,5449. koop, k., newell, r.c. & lucas, m.l.1982a: microbial regeneration of nutrients from the decomposition of macrophyte debris on the shore. mar. ecol. b o g . ser. 9,y 1-96. koop, k.. newell, r.c. & lucas, m.l. 1982b: biode gradation and carbon flow based on kelp (ecklo nia maxima) debris in a sandy beach microcosm. mar. ecol. b o g . ser. 7 , 3 15-326. lundgren, b. 1981 : fluorescein diacetate as a stain of metabolically active bacteria in soil. oikos 39. olsson, f.c.w. 1950: quantitative estimates of fila mentous algae. trans. am. microsc. soc. 69,272-279. persson, t. 1983: influence of soil animals on nitrogen mineralization in northern scots pine forest. 4. 117-126 in lebrun, p. et al. (eds): new trends in soil biology. dieu-brichart, ottignies-lourain-la neuve. petersen, h. & luxton, m. 1982: a comparative analy sis of soil fauna populations and their role in decom position processes. in petersen, h . (ed.): quantita tive ecology of microfauna and animals in soil and litter. oikos 39.287-388. 7 7 ramsay, a. 1983: bacterial biomass in ornithogenic soils of antarctica. polar biology i , 221 -225. sveum, p. (in prep.): decomposing kelp (laminaria) on arctic shorelines. soderstrom, b. 1977: vital staining of fungi in pure cultures and in soil with fluorescein diautate. soil biol.biochem. 9 , 5 9 4 3 . trolldenier, g . 1972: fluoreszenzrnikroskopische zahlungen von bodenbakterien. 1. historischen uberblick mit beschreibung eines verfahres zur zahlung von bodenbakterien i. trockenpreparaten nach farbung rnit acridionarange. zentrbl. bakr. hyg. abt. i i 127,2540. ulber, 9. 1983: einfluss von onychiunrsjmnfus gisin (collembola, onychiuridae) und folsorniajrneraria (l.) (collembola, istotomidae) auf pyrhium ultimum trow., einen erreger des wurzelbrandes der zucker riibe. pp. 261-268 in lebrun, p. et al. (eds.): new trends in soil biology. dieu-brichart, ottignies louvain-la-neuve. micromonas pusilla (prasinophyceae) as part of pico and nanoplankton communities of the barents sea jahn throndsen and svein kristiansen throndsen, j . & kristianaen. s . 1991: m i c r o m o m s p d / a (prasinophyceae) a h part of picoand nano plankton communities in the barents sea. pp. 201-207 in sakshaug. e . . hopkins. c. c. e. & britsland, n . a . (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, 12-16 may 1990. polar research 10(1). micromonas pusilla (butcher) manton & parkc appears to bc a prominent member of the barcnts sea picoplankton community as revealed by the serial dilution culture method. cell numbcrs frcqucntly exceeded 10' cells i ' , though they usually varied between 10' and 10'cells i ' . a number of othcr identifed and unidentified taxa were recorded and quantified. distribution relative to the marginal icc zonc 15 reported. jahn throndsen a n d svein kristiansen. departmenr of biology. marine botuny division. university of o s l o . p . 0. box 1069 blindern, n-0316 oslo 3, n o r w a y . introduction investigations on flagellates in the barents sea began with the work of wulff (1916), who reported the presence of many species previously described from temperate waters. meunier (1910), working in the rieighbouring area, the kara sea, likewise added to the knowledge of arctic flagellate plankton and described new species from the area. earlier investigations in polar oceans were restricted either to laboratory work on preserved material or to shipboard obser vations of living material from net hauls. recently, quantitative information on the smaller plankton of the barents sea was obtained by reynolds (1973). who made direct counts, and throndsen (1970), who used a dilution culture technique. species information from arctic areas has on the whole been obtained by electron micro scopy studies on dried preparations of cell material fixed with osmic acid (e.g. thomsen 1982, manton et al. 1975, 1976). this method, however adequate for revealing submicroscopical details necessary for identification, gives very poor indications of cell numbers in the sea. the present survey elucidates the importance of euka ryotic picoand nanoplankton in the marginal ice zone in arctic marine waters. the serial dilution culture method was applied i n order to give quan titative as well as qualitative information. when first used in the arctic in 1969 (thrond sen 1970), the dilution culture technique revealed the presence of a number of genera and species new to the waters off spitsbergen and b j ~ r n ~ y a . materials and methods water samples were collected from stations at different distances from the ice edge (fig. 1, table 1) during pro mare cruises in the barents sea i n the spring (april) of 1986 and during the summers (june) of 1984 and 1987. the sampling device was assumed to be non toxic; the effect of possible undetected toxicity was minimised by the relatively short handling time and the dilution of the samples into growth medium with chelating agents included. serial dilution cultures (throndsen 1978) were set up in erd-schreiber medium (s = 32.5) 1-2 hours after sampling. the cultures were kept in dim light at 2 4 ° c during the cruise and transportation and in the laboratory culture room at the department of biology, university of oslo. the cultures were examined after 6-8 weeks by bright field and anoptral contrast microscopy, with additional observations by transmission elec tron microscopy. the presence and absence of each species throughout the dilution culture series made it possible to estimate the cell numbers present in the original sample (mpn = most probable num ber). 202 j . throndsen & s . kristiansen 7 2 35 4 0 35 i \ 4 0 fig. 1 . map of the barents sea showing the location of the stations sampled for serial dilution cultures: solid circles = no ice; open circles = open pack ice: triangles = close pack ice. results picoplankton (1-2.5 pm) micromonas pusilla (butcher) manton & parke appears to be a prominent member of the pico plankton community as revealed by the methods applied. cell numbers frequently exceeded lo7 cells i l , though they usually varied between 10' and 106cells i-' (tables 2, 3). out of 17 sta tions sampled, m . pusilla was detected at all but three. other eukaryotic picoplankton comprised green coccoids 1-1.5 pm, 2 pm, and 2.5-3 pm in size. these were not studied in further detail but probably included nonmotile m . pusilla, the newly described bathycoccus prasinos (eikrem & throndsen 1990), and possibly also undescribed coccoid eukaryotic picoplankton species. prokaryotic picoplankton were not prominent in the dilution cultures and are thus ignored in this paper. nanoplankton (2.5-20 pm) among the smaller nanoplankton (< 5 pm, tab les 2 , 3 ) identified, the five most abundant species were the prasinophycean mantoniella squamata, the prymnesiophytes dicrateria inornata and imantonia rotunda, and the pedinelloid chry sophyte pseudopedinella tricostata. table 1. stations sampled for serial dilution cultures in the barents sea in 1984. 1986, and 1987 year date ice condition station position depth 1984 4 june 3 june 8 june 9 june 10 june 11 june 13 aug open pack 670 no ice 676 no ice 721 no ice 723 no ice 744 no ice 847 open pack 733 77" 10". 33"b'e 76"40'n, 33"04'e 76"48'n. 33"07'e 76"lo'n. 35"00'e 76"32'n. 45.00'e 75"45'n, 45"00'e 76"40'n. 33"04'e 5 m 25 m 0.5,10.20.30,50.75 m 10 m 5.15.75 m 10 m 10 m 1986 10 april open pack 018 75"29'n. 32"06'e 10 m 15 april no ice 028 74"00'n. 27"il'e 10 m 16 april open pack 03 1 74"5u'n. 27"46'e 10 m 17 april close pack 037 74-54! n , 32"59'e ice 19 april close pack 043 75"54'n. 30"45'e ice 20 april close pack h1 21 april no ice 052 74'33". 27"50'e 10 m, bloom 75-26". 34"15'e 10.30 m under ice 1987 2 june no ice 945 74-11". 28"00'e 10 m 3 june no ice 96 1 75"55'n. 30"30'e 10.30 m 8 june no ice 994 74"30'n. 3 i"3 1 'e 10.60 m nanoplankton communities of the barents sea 203 table 2. occurrence of micromonas pusilla and selected groups of plankton on stations sampled in the barents sea in junc 1986. mpn in lo’ ccllsl-’. no cells recorded. stations species/groups 670 733 676 721 723 744 ice condition open pack ice no ice sampling depth 5 rn 5 m 2 5 m om 10 m 10 m micromonas pusilla other eukaryotic picoplankton nanoplankton 4 pn nanoplankton > 5 pm diatoms heterotrophic flagellates >24 000 78 68 170 270 31 48 0 . 4 94 120.2 73.2 2 0 56 0.8 40 19 72.2 0.2 20 18 240 920 260 260 35 0 . 4 6 table 3. occurrence of micromonos pusilla and selected groups of plankton in the barents sea in apnl 1986. mpn i n 10‘ cells i ] , no cells recorded. stations 037 043 h1 018 031 028 052 ice condition close pack ice open pack ice no ice ~~~~~ ~~ i .8 other eukar. picoplkt. 110 210 60 6.8 0.8 micromonas pusilla 2 0.2 40 i3 ooo nanoplankton < 5 pm 2.2 22 40 55 120 nanoplankton > 5 pm 0.2 0.2 20 heterotroph. flags 176 22 diatoms 19 500 24 300 84 100 1830 142 254 mantoniella squamata (manton & parke) desi kachary (3-5 pm) belongs to the smaller nano plankton. it was recorded on three occasions only. other prasinophycean flagellate species, e.g. of pyramimonas, were even more scarce in the dilu tion cultures. non-motile stages of pterosperma, halosphaera and pachysphaera were encountered in small numbers only. dicrateria inornata parke (3-5.5 pm) and iman tonia rotunda reynolds (2-4 pm) are almost indis tinguishable in the light microscope, and for this reason they were referred to as dicrateria inornatallmantonia rotunda. most often samples studied in the electron microscope appeared to contain imantonia rotunda which is characterised by fine oval-circular, cartwheel-patterned organic scales covering the cell surface. dicrateria inor nata is naked and information from direct em preparations was rather limited. larger nanoplankton (> 5 pm) (tables 2 , 3) was usually dominated by chrysoor crypto phytes. pseudopedinella pyriformis n . carter (5 8 pm) was the most common chrysophyte ident ified, the smaller p . tricostata (rouchijajnen) thomsen (4-5.5 pm) was less common, but re corded both in 1984 and 1987. motile cells of the genus phaeocystis (4.5-8 pm) were also occasionally significant. a new species “arctic flag sp.#” was probably the most common taxon among the larger nano plankton. the species has flattened cells 9-12 pm long, with two ventrally inserted flagella, one pointing forwards, the other directed posteriorly. the single chloroplast is golden brown. a more extensive description of the species will be pub lished elsewhere. cryptophycean species in the size range 1c 20pm were frequently present. species of the genera isoselmis, plagioselmis and chroomonas covered the whole nanoplankton size spectrum, whereas specimens which were tentatively ident ified as cryptomonas prora conrad & kufferath were in the upper size range (18-21 pm). this species has been reported to bloom during winter 'e pue sqqel ui .a.a uoiyueldoueu iaqio woij palwedas pue sdnoj% se 01 paiiajai kluo allensn ajam smoieip pue saie[[a%eu siqdoiioiaiah .payyuap! sezn iaqsing sua~sauun.iq 'h lluo sapads s!wias!wa~ aqi 30 '(pgji qieiajjny 78 peiuo3) wn!%pg ui siaiem qslyseiq ui (~,,s.o-) as! aqi iapun punoj uaaq aaeq 01 uaha pue 3 i 3 d nunoplankton communities of the barenrs sea 205 have been used to allow for a better estimate of these high m . pusilla populations. close to the ice edge (station 031), mpn up to 13 million cells i-' was recorded in open pack ice in april 1986 (table 3). for the stations in oceanic ice-free waters, the micromonas numbers varied between lo6 and lo3 cells i ' , except for station 028 where it was not recorded. the lowest recorded concentrations of m . p u s illa were near the limit of detection (180 cells i ' ) and were found at 20 m depth at station 721, 15, 20 nm south of the ice edge in 1984 and at 30 m under the ice at station h-1 in 1986 (table 4). depth distribution (station 721) information on depth distribution is sparse. the mpn for micromonas pusilla and four groups of picoand nanoplankton from surface to 75m depth at station 721 (1984, table 5) may, however, reflect a common situation; the diatoms had their highest numbers in the surface layer and at 20 m. m . pwilla was likewise numerous at the surface, but its deeper maximum was at 50 metres. at station 733 three depths were sampled show ing the highest concentrations of micromonas at 5 m, slightly lower at 15, and lacking at 75 m. at station 721 dilution cultures from 5 depths (table 5) showed that the dominating populations of viable picoand nanoplankton were confined to the upper 30 m. the population at 75 m con sisted of non-motile picoplankton and nano plankton flagellates: mantoniella squamata, pseu dopedinella pyriformis and the heterotrophic pseudobodo minimus ruinen, as well as an unidentified heterotrophic gymnodinium species. m . pusilla was most numerous at the surface, but the concentration was only 7 x lo4 cells i-'. the concentration of pseudopedinella pyri formis varied from 6 lo3 cells i ' at the surface to 4 . lo2 cells 1-' at 75 m, with a maximum of 45 lo3 at 30 m. occurrence of other flagellates pseudopedinella species were most common in summer samples, the highest mpn were 45 lo3 cells.1-' (station 721, 3 0 m depth) for p . pyri formis whereas p. tricostata never exceeded 3.7 lo3 cells i ' . p . pyriformis was, however, found from the surface to 75 m depth. heterotrophic flagellates of nanoplankton size were present at most stations. mpn varied from the detection limit 180cells i ' to 2.1 * lo5 cells i ' . the highest cell number recorded was for par aphysomonas at station 994, 60 m in june 1987, whereas 1.7 lo5 cells i ' of an unknown species was estimated from an under-ice sample at station 037. discussion the sdc method the serial dilution culture method is known to be selective (throndsen 1978), and other species than those recorded may certainly also have been present in the samples. lack of viability of the specimens introduced to the dilution tubes, and competitive relations in the single tube, may have reduced the number of tubes with detectable growth of an otherwise culturable species. the culture conditions and the medium used will further influence growth, and hence the mpn estimates (see e.g. furuya & marumo 1983, jochem 1990). the presence of the species recorded, however, cannot be disputed, and they certainly belong to the viable part of the plankton community. heterotrophic species will only grow provided adequate food organisms or compounds are present, and there is certainly a lack in regis tration especially of heterotrophic dinoflagellates. technically, correct mpn estimates for cul turable species will be impossible if their original concentration is too high compared with the dilu tions used. the five step dilution used ended with an inoculum of 0.1 pi of the original sample. during the work in the barents sea this caused limitations in some of the estimates of the mic romonas pusilla population; mpn estimates had to be given as > 24 million cells 1-'. for larger species such high numbers of cells would have caused discoloration of the water and hence given visual advice regarding the number of dilution steps. the mpn estimates could be compared with direct counts at station 994 (t. f. thingstad pers. comm.). the mpn for micromonas at 10 m depth was higher than 2.4. lo7 cells l-', whereas direct counts for picoplankton (not identified to species) gave 1.5 lo7 cells i-'. this indicates that mic romonas probably was the major if not the only species in the group. the difference in cell number 206 j . throndsen & s . kristiansen estimates is an acceptable discrepancy considering the methods used. at 60rn the difference was significant, mpn estimate for micrornonas was 1.7. lo6 cellsl-* whereas the counts gave neg ligible numbers o n l y . phaeocystis mpn estimates were related t o colonies (which could contain a variable number of cells) and hence gave lower numbers than the direct cell counts. occurrence related to the ice micromonas pusilla was apparently not par ticularly favoured by the conditions in or very close to the ice, though fairly high cell numbers were recorded also at the ice edge (fig. 1 , table 4), the latter being in accordance with the tol erance of this species for low salinities as well as low temperatures (throndsen 1976; throndsen & heimdal 1976; jochem 1990). the low surface to volume relation is likely to give the pico plankton species their best competitive advantage under oligotrophic conditions, and it is therefore not surprising to see that diatoms (mostly nan oplanktonic species were recorded by the method applied) rather than picoplankton were dom inating in the ice underside samples. the oppor tunistic m . pusilla, however. was very abundant in the surface water of the marginal ice zone. information on m . pusilla from other polar oceans is mostly restricted to identification in direct em preparations, and with no real evidence for cell concentrations. also for eukaryotic pico plankton in general the quantitative information from these areas is very sparse. from the tromso area, which is north of the arctic circle and hence is exposed to "polar" light conditions, m . pusilla proved to be present in the sea during all the seasons, but with its highest numbers in summer (throndsen & heimdal 1976). depth distribution micromonas pusilla is known to have a low light saturation level for growth (throndsen 1976). and its depth distribution in subtropical areas is extensive: viable cells are found down to 500 m i n the bay of biscay (manton & parke 1960) and 600111 off the coast of japan (kuroshio area. throndsen 1983). hence the presence of m . pus illa at 75 rn in the barents sea is to be expected. its distribution in the deeper water masses, including productive areas at high latitudes, further con firms its ability for survival and growth. studying the subsurface chlorophyll maximum in the western north pacific ocean, furuya & marumo (1983) found micromonas (probably m . pusilla) to be the most abundant genus in this layer. in the gulf of panama m . pusilla appeared to follow the general distribution of chlorophyll from 10 to 100m depth; the deeper maximum here was at 75 m (throndsen 1976). picoplankton importance in polar waters though micromonas pusilla and other eukaryotic picoplankton species have been reported from both arctic (throndsen 1970; thomsen 1982) and antarctic waters (h. a. thomsen pers. cornm.), little is known about their importance relative to the prokaryotic picoplankton in these areas. cyanobacteria are frequently recorded by the dilution culture method e.g. in coastal areas of the temperate zone, but they were not common in the present samples. based on the methods known today, future efforts i n this field should include an integrated use of serial dilution cultures, direct em prep arations, epifluorescence counts, size fractionated carbon uptake measurements, and laboratory growth and pigment studies. acknowledgements. t h e authors thank the officers and crew ance. this project was supported by the norwegian research program for marine arctic ecology (pro mare). of r / v g 0 sars. k/v andenes and k / v senja for their assist references conrad. w . & kufferath. h . 1954: rechcrches sur les eaux saumatres des environs de lilloo. 2 . partie descriptive. mem. insr. r . sci. not. belg. 127. 1-346. eikrem. w. & throndsen. j . 1990: the ultrastructure of bathy coccus gen. nov. and b. prasinos sp. nov.. a nonmotile picoplanktonic alga (chlorophyta. prasinophyceae) from the mediterranean and atlantic phycologia 29. 344350. furuya. k. & marumo, r. 1983: the structure of the phyto plankton community in the subsurface chlorophyll maxima in the western north pacific ocean. 1. plankton res. 5 . 393 406. jochcm. f. j . 1990: on the seasonal occurrence of autotrophic naked nanoflagellates in kiel bight. wcstern baltic. estrtnr. coast. shelf sci. 3 1 . 189-202. manton. i . , & parke. m. 1960: further observations on small grcen flagellates with special reference to possible relatives of chromulina pusilla butcher. j . mar. biol. ass. u . k . 39, 275-298. manton. i . . sutherland. j . & leadbeater. b s. c. 1975: four new species of choanoflagellates from arctic canada. proc. r . soc. london, ser. b 189. 15-27. nanoplankton communities of the barents sea 207 manton. i . . sutherland. j . & leadbeater. b. s. c. 1976: further observations on the fine structure of collared flagellates (choanoflagellata) from arctic canada and west greenland. can. j . bot. 54, 1932-1955. meunier, a . 1910. microplankton des mers de barents et de kara. duc d'orl6ans campagne arctique de 1907, bruxelles. reynolds, n . 1973: the estimation of the abundance of ultra plankton. br. phycol. j . 8. 135-146. thomsen, h. a. 1982: planktonic choanoflagellates from disko bugt. west greenland, with a survey of the marine nano plankton of the area. meddr. g r ~ n l a n d . biosci. 8 , 1-36. throndsen. j . 1970: flagellates from arctic waters. n y t t mag. bot. 17. 49-57. throndsen. j. 1976. occurrence and productivity of small mar ine flagellates. norw. j . bot. 23. 269-293. 355 pp. throndsen, j . & heimdal. b. r. 1976: primary production, phytoplankton and light in straumsbukta near tromsb. astarte 9 , 5 1 4 0 . throndsen. j . 1978: the dilution culture method. pp. 218 224 in sournia. a . (ed.): phytoplankton manual. unesco monographs on oceanographic methodology, no. 6. paris. throndsen, j. 1983: ultraand nanoplankton flagellates from coastal waters of southern honshu and kyushu, japan (including some results from the western part of the kuroshio off honshu). working party on taxonomv in the akashiwo mondai kenkyukai fishing ground preservation dillision, research department, fisheries agency, japan. 62 pp. w u l f f , a . 1916: ueber das kleinplankton der barentssee. arb. dt. wiss. kommn int. meeresforsch. a . a w dem lab oratorium fur lnternationale meeresforschung in kiel. biol. abt. no. 28, 95-125. one-year records of current and bottom pressure in the strait between nordaustlandet and kvitoya, svalbard, 1980-81 k . aagaard. a . foldvik, t. gammelsrbd and t. vinje aagaard, k . , foldvik, a , . g a m m e l s r ~ d , t . & vinje, t. 1983: one-year records of current and bottom pressure in the strait between nordaustlandet and k v i t ~ y a . svalbard, 198&81. polar research i n . s . . 107-113. we have obtained one year of measurements from a subsurface instrumented mooring carrying two current meters and one bottom pressure recorder in the strait between nordaustlandet and kvitcbya in the northeastern svalbard archipelago. the observations show a mixed tide with typical amplitudes 0.4 d b and 1ocm sec-i. the semidiurnal tide is characterized by a progressive wave propagating toward the south. together with a cross-channel baroclinic mode. the annual average (non-tidal) current is less than 2 cm secc’ toward the north-east, suggesting that the transport into the arctic ocean is approximately 0.2 x lo6 m3 ski. k . aagaard, university of washington, 4057 rooseuelt way, n. e. seattle, washington 98105. u . s . a . ; a . folduik and t . gammelsr@d, geofysisk institutt, aud. a , uniuersitetet i bergen, 5014 bergen. norway: t . vinje, norsk polarinstirurt, rolfsrangueien 12, 1330 oslo lufthaun, norway; december 1982 (reorsed february 1983). introduction in this paper we present the results from a sub surface mooring between kvitoya and nordaust landet in the northeastern svalbard archipelago (fig. 1). t h e rig was launched from the swedish icebreaker ymer on 30 july 1980 and recovered from t h e norwegian vessel l a n c e on 25 august 1981. i t consisted of two aanderaa rcm-4 cur rent meters at 75 m and 255 m, and o n e aanderaa fig. i . map of svalbard showing positions of mooring and ctd section 108 k . aagaard et al. . . f 3 r . . . tg-2a pressure recorder at the bottom (260 m ) . t h e sampling interval was o n e hour. an apparent deterioration in the speed recording of the lower current meter over the last 20 weeks of deploy ment caused the only data gap. pressure measurements the bottom pressure record reflects the combined effect of variations in sea level ( e . g . that due to tides). varying atmospheric pressure. and baro clinic currents. fig. 2 shows the pressure record ing for the two months immediately following the launching. a typical mixed tide prevailed. a i t h the semidiurnal components dominating. the fortnightly period is due to the interference of the semidiurnal periods m: and s:. t h e maximum amplitude is seen to be roughly 0 . 4 decibar. equiv alent to 0 . 4 m in sea level. also presented in fig. 2 is the residual pressure . ~ ._ . . . . ....._i__ .1 . 1 1 5 : , e , . o , i p r s ; f i g . .? t h e p o u c r spectrum for the entire one-year hortom pressure record. cumputcd using the maximum entrop) method. the lrequencies of the malor tidal constituents are also ahti\\n. .. . ._ . fig. 2 . hourly bottom pressure from august t o september 1980. time in julian days. also shown is the low-passed series, using a filter with a 40 hr cut off. after tidal variations have been filtered out using a low-pass filter which suppresses variations with periods shorter than 40 hours. t h e amplitude of the filtered curve is equivalent t o about 10 cm and represents the combined effects of low-frequency currents and atmospheric pressure variations. t h e power spectrum of the pressure record (fig. 3) yields the expected tidal bands. t h e large subharmonic components which appear near 8 h r , 6 hr. etc.. are typical for shallow water tides, and arise from the non-harmonic tidal wave form in shallow water. t h e amplitude and phase of the major tidal constituents have been computed from the entire one-year record using foreman’s (1977. 1978) method. t h e results a r e listed in table 1 . current and temperature measurements fig. 4 shows a temperature, salinity, and density section across the strait two days after the recov ery of the mooring. t h e lower current meter had been situated near the bottom in the warmest water, while the upper meter was a t the position of the cold core at 75 m d e p t h . portions of t h e various temperature and veloc ity records are shown in fig. 5 . covering the same period as the pressure record in fig. 2 . as with the pressure signal, the tides also dominate the currents. t h e amplitude and phase of the major tidal constituents have been computed using the full-length records, and the results are listed in table 1. t h e v (north)-component of the upper current meter exhibits the largest amplitude, about 10 cm sec-’. power spectra of the current components (not shown) are similar to the power spectrum for the pressure record (fig. 3 ) . t h e temperature spectra (fig. 6) show no tidal current and bottom pressure records 109 table 1. major tidal constituents for the upper current meter (upper numbers). the lower current meter (lower numbers) and the pressure. positive minor axis denotes counter-clockwise rotation. the angle of inclination denotes the orientation of the major axis and is measured in degrees counter-clockwise from east. greenwich phase is referred to the northcrn major semiaxis for the current and to high water for the pressure. ~ ~~~ current measurements pressure measurements major minor angle of greenwich greenuich axis axis inclination phase amplitude phase constituent cm 7ec-l cm sec-' degree5 degrees dectbars degrees 0 1 0.45 -0.18 147 _ _ 34 0.25 -0.01 158 26 0.01 320 pi 0.47 -0.00 95 0.24 0.04 109 1.29 0.88 0.09 104 0.16 117 68 67 67 68 0.02 0.07 '95 305 0 04 68 n2 1 6 5 -0 15 x9 230 0 70 0 39 104 237 265 3.61 2.37 102 267 337 1.39 0.73 39 268 0.21 47 m2 8.63 -2.18 96 0.06 152 s2 3.50 -1.32 105 influence other than a rather broad semidiurnal pressure, current and temperature records: the peak, probably due t o a semidiurnal internal tide results are shown in fig. 7 . the filtered currents (see discussion below). t h e different spectral levare weak, about 2 cm sec-', and exceed els for the two instruments reflect the weaker 5 c m s e c ' only for short periods of time. the temperature strat:clcation in the lower layer (cf. average flow is approximately northeast, i.e. into fig. 4). the arctic ocean, as is also apparent from the we have applied the 40-hr filter t o the entire progressive vector diagrams (fig. 8). 0' sd d i s t . i n kh: terperrture i n o e g . c 0 25 5 0 0 so 0157. 1n k f l : 0187. i n kn: p r r c t i c r l s r l i n i t y s i g v r t h e t r . fig. 4 . a temperature. salinity and density section across the strait betwecn nordauatlandet and kvitbya. the upper numbers identify the oceanographic stations. the deepest observations are marked with crosses and the positions of the current meters with black dots. 110 k . aagaard et a l . the average velocities in the upper and lower layers are 1.8 cm sec-' and 0.5 cm sec-', respec tively (the latter value was calculated u p until 4 april only). from this we estimate that the annual average flow through the strait probably does not exceed about 0.2 x 10bm3 sec-' (0.2 sv) toward the northeast. in terms of mass balance for the arctic o c e a n , this is a small contribution (scor working g r o u p 58,1979); for example, it is prob ably less than 5 % of t h e west spitsbergen current transport. t h e temperature records (fig. 7) show that the structure revealed in fig. 4, with a cold core above a warm bottom layer, is maintained throughout the year. current and bottom pressure records 111 discussion neither the filtered series themselves (fig. 7) nor their power spectra (not shown) indicate distinct long-term periodicities. there are, however, a few events of strong northerly currents at both instruments (e.g. 28 january and 23 february, cf. fig. 7) which coincide with anomalously high bottom pressure. on both occasions, relatively intense cyclones passed over the northern barents sea, and the strong current events were probably forced by the atmospheric events. 20 10 8 7 6 5 1 p p e r , o d ( h l r ) the rotary spectra for the current records are shown in fig. 9. a comparison of the energy fig. 6 . power spectra of temperature. -2.w i i 112 k . aagaard et al. 04 p ~ . . . . , . . . , , . , . . , . . . . , . , , 1 l i00 0. ico. zdo . 3w. 400. d i s p l a c e m e n t e a s t w a r d s ' k r r 1 fig. 8. progressive lector diagram for the two current meters. circles (uppcr meter 1 and crosses (lower meter) denote position every 30 days levels in the tidal bands shows that the counter clockwise components are equal in the upper and lower layers. whereas the energy in the clockwise component is smaller at the lower instrument. particularly for the semidiurnal tide. t h e distri bution of energy in the tidal bands also shows that the associated tidal currents rotate in opposite directions at the two instruments. clock wise in the upper layer and counter-clockwise in the lower. this is clearly seen in fig. 10. where the tidal current ellipses are plotted; the current vectors are shown at the time of high tide. the maximum southward flow in both layers is seen to coincide with high tide. thus the north-south tidal currents have the characteristics of south ward-propagating progressive waves. a quarter period after high tide the maximum westward flow in the upper layer coincides with maximum eastward flowin the lower layer. t h e motion across the axis of the channel thus has the charac teristics of a standing internal wave. a c k n o k l e d g e r n e n r , . the measurements described in this 95 p e r j i f ' i l ~~ ~ . -.--i l 1 _ ~ l , , ~-~ --i t t ~ l ..~. . -~~ , ~. .c? . icr . -)1 'i' i t i i l t n c " : cph fig. y. rotary current spectra. the frequencies of the major tidal constituents are indicated report were the combined efforts of the norwegian polar research institute. the geophysical institute of the university of bergen. and the university of washington. we express our appreciation to the officers and crew of the ymer and the lance for their enthusiastic cooperation in carrying out the deployment and dredging operations: to clark darnall and richard tripp at the university of washington for help with instrumentation and data handling; and to tor torresen and stein sandven at the geophysical institute. university of ber gen. for programming and helpful discussions. knut aagaard was supported financially by the office of naval research through contract no. n00014-75-c-0893 and by the national science foundation through grant no. dpp 81-00153. references foreman. m. g . g. 1977: manual for tidal heights analysis and prediction. pat@ marine science report 77-10 (corr. 1979). institute of ocean sciences. patricia bay, sidney. b.c. foreman. m. g. g . 1978: manual for tidal currents. analysis and prediction. pacific marine science reporr 78-6 (corr. 1979). lnstitute of ocean sciences, patricia bay, sidney, b.c. scor working group 58, 1979: the arctic ocean heat budget. reporr y o . 52. geophysical institute, university of bergen. norway. current and bottom pressure records 113 i is indicated and the arrows show fig. 10. tidal ellipses for the major constituents according to table 1. the shaded ellipses refer to the lower current meter. the direction of rotation the tidal current at the time of high water 2 w+e s ocrn/s 1 2 ‘l l 8 8 i upper inst 4888 l o w e r inst i t o n e d 1 estimating little auk (alle alle) breeding density and chick-feeding rate using video surveillance research note estimating little auk (alle alle) breeding density and chick-feeding rate using video surveillance anders mosbecha, peter lyngsa,b & kasper lambert johansena adepartment of bioscience and arctic research center, aarhus university, roskilde, denmark; bchristiansø biological field station, christiansø, denmark abstract high arctic ecosystems are under change and need to be monitored. we studied little auks (alle alle), the most abundant seabird in the north atlantic, in their main breeding area in the north water polynya region of high-arctic north-west greenland. we developed a method for estimating breeding density and chick-feeding rate based on video surveillance. as the nests of little auks are secluded between rocks and cannot be directly observed, the method rests on detailed recording of feeding events, when parent birds arrive from the sea with filled gular pouches and disappear into the scree to feed their chicks, supplemented with recording of fledging and pre-fledging behaviour of chicks outside the nesting holes. we installed video cameras in two study plots during the late chick-rearing and fledging periods 2 – 11 august 2012 and 5 – 12 august 2013, and the method proved useful for estimating the density of active nests immediately prior to fledging (which corresponds roughly to productivity of fledglings/m2). the densities of active nests for the two plots in 2012 and 2013 ranged between 1.06 and 1.63 nests/m2, and an average of 9.1 feeds/chick/day (n = 8 pairs, 3 × 24 h, 219 feedings) was recorded for this late stage of the chick-rearing period. our video surveillance method has advantages over the mark–resight methods and other techniques used to monitor little auk colonies. keywords seabird colony monitoring methods; seabird ecology; north-west greenland; north water polynya; high arctic abbreviations wgst: western greenland summer time; sd: secure digital introduction climate will change faster in the arctic than further south and monitoring population trends for key species is pivotal for protecting biodiversity, understanding ecosystem change and taking adaptation actions (arctic council expert group on ecosystem-based management 2013; meltofte 2013; irons et al. 2015). the little auk (alle alle) is the most abundant seabird in the north atlantic (barrett et al. 2006). it breeds in extensive colonies in the high arctic, laying a single egg in cavities in scree on steep mountain slopes (stempniewicz 2001). the little auk will be exposed to climate-driven changes in the marine environment, but the potential to adapt via a range shift of breeding colonies towards the north into the arctic ocean is limited. the threat of climate change to little auks has therefore received scientific attention with primary focus on the linkages with the high-arctic marine food web during the breeding season (karnovsky et al. 2011; grémillet et al. 2015). northern oil activities, expansion of shipping routes and long-distance, atmospherically transported contaminants have been suggested as other potential threats (fort et al. 2013) and monitoring little auk population trends has been recommended (irons et al. 2015). however, as little auk nests are secluded between rocks, assessment of breeding density is not straightforward. estimates have been produced by attempts to count nests directly (evans 1981; stempniewicz 1981) or by calculating nest density based on the proportion of resightings of a known number of marked birds in a study plot, followed by comparisons with the number of unmarked birds observed in the plot (mark–resight model; e.g., isaksen & bakken 1995; kampp et al. 2000). as most nests in our study area in north-west greenland were located deep in the scree, a direct count of nests by checking holes with an arm or a tube inspection camera was not possible. the mark– resight model was also unsuitable in our case because of an unknown proportion of non-breeders (e.g., kampp et al. 2000) and, especially, because of the presence of an unknown and variable number of visitors from other parts of the breeding colony in our study plot at any given time. this violates the assumption of the mark–resight method that birds observed in the study plot are actually breeding in the plot or form part of a known fraction of non-breeders. we developed an alternative method based on video surveillance of study plots during the late chick-rearing and fledging periods, which allows us to estimate the density of occupied nests immediately prior to fledging. as little auks raise only a single chick, this figure contact anders mosbech amo@bios.au.dk department of bioscience, aarhus university, frederiksborgvej 399, 4000 roskilde, denmark polar research, 2017 vol. 36, 1374122 https://doi.org/10.1080/17518369.2017.1374122 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1374122&domain=pdf corresponds closely to the productivity of fledglings per area unit. the estimate is based on detailed recording of feeding events, when parent birds arrive from the sea with filled gular pouches and disappear into the scree to feed the chicks. the choice of study period allowed us to supplement these data with recording of fledging events and associated pre-fledging behaviour of chicks outside the nesting holes. as an integrated part of the method, chick-feeding rates are also obtained, and these potentially constitute another important monitoring parameter. material and methods we studied little auks in their main breeding area in north-west greenland, where an estimated 33 million pairs, or 80% of the global little auk population, breed in colonies distributed within a range of 325 km along the eastern shores of the north water polynya (boertmann & mosbech 1998; egevang et al. 2003). the study was conducted within a large colony in the valley of qoororsuaq (76°16ʹn, 68°58ʹw), 21 km south-east of cape atholl and 3 km north-west of the pituffik glacier (fig. 1). we selected two study plots (mv and vv) within the western part of the colony on the north slope of the valley. both plots were positioned in boulder scree with large stones (average diameter 30 – 40 cm). the mv plot was placed in what we deemed to be a high-density area and the vv plot in a semi-highdensity area—as opposed to lower density areas on the outskirts of the colony. the boundaries of the plots were marked with dots of red paint. following the mountain slope, the surface area of the mv plot was 6.75 m2 and that of the vv plot 4.71 m2. at each plot, we installed a jvc everio gz dual slot camcorder (in 2012 the hm200, in 2013 the ex515), each equipped with two sd memory cards. the video cameras were placed on tripods and protected against the weather by ewa marine rain covers. at plot vv, the video camera was placed above the plot and 3 m uphill from the plot border. at plot mv, the video camera was situated at the same level as the plot, 4.6 m from the plot border. the video cameras operated in xp-mode (17 mbps, vbr 1920 × 1080, two-channel digital dolby sound) and were powered by external batteries (vision 6fm 12v 7.2 ah). we charged the batteries in camp, replacing them and the sd cards on a daily basis. both video cameras recorded during late chickrearing and fledging in the periods 2 – 11 august 2012 and 5 – 12 august 2013, capturing a total of 344 h and two minutes of video footage. as feeding and fledging activity in the colony primarily took place between 24:00 and 10:00 wgst, the video cameras were usually started around midnight and continued recording until the sd cards ran full 8 – 10 h later. however, during 8 – 10 august 2013, the video camera at plot mv ran continuously for 24 h/day to obtain the full diurnal activity pattern. figure 1. map of the study area and location of the study site (red dot). the distribution of little auk colonies is shown in pale red (after boertmann & mosbech 1998). basemap reproduced with permission from danish geodata agency. 2 a. mosbech et al. in previous years, six of the birds breeding in the mv plot had been ringed with a metal ring and/or colour rings and on 5 – 6 august 2013 we individually marked a further five birds (three males, two females) from three pairs (nests 6, 8 and 9) in this plot using picric acid. all marked birds were sexed by analysing dna from feather samples (see “molecular sexing” in frederiksen et al. 2014). in the vv plot, all birds were unmarked. food-carrying adults, returning from sea to feed the chick, are easily identifiable, as they carry the food in a bulging gular pouch. they always land some distance away from their nest, often in groups consisting of several food-carrying birds from the same area. they then approach their nest entrance in a series of short flights or jumps (average duration of approach 43 s, range 2 s – 2:50 min, n = 84), and disappear into a nesting hole to feed the chick. when undisturbed, they reappear with an empty gular pouch after a few minutes (average duration in nest 3:34 min, range 1:01 – 8:31 min, n = 50). observations of marked birds revealed that some birds used several entrances/exits to the nest, and that different pairs in some cases used the same surface entrances. however, observations of marked birds also revealed that each bird tended to use distinct routes of approach (fig. 2). this makes individual recognition of unmarked birds possible and helps resolve matters in cases of multiple/overlapping entrances. in the days prior to fledging, the chicks start to appear outside the nesting hole for short periods, occasionally conducting a characteristic wing-flapping and interacting with a parent. the chicks are distinguishable from adult birds and often distinguishable from each other (e.g., based on different throat-feather patterns). this pre-fledging behaviour of chicks, and the actual fledging event, form supplementary cues to establishing the presence of active nests. estimating the number of active little auk nests on the basis of the video footage can be described as a process of pattern finding, gradually piecing together these different bits of information. all video footage was watched on a computer by the same observer (pl) using vcl media player or daum potplayer with the sound turned on, making extensive use of the possibility to speed up when nothing happened (×2 – 4), and to stop, rewind and re-play in slow motion when a significant event took place. each food-carrying little auk landing in or just outside the plot was followed until it entered a nesting hole and often recorded again when exiting the nest. for each such feeding event, route of approach, identity of the bird (if possible), and time and position of entry and exit were recorded. the entrance/exit holes were numbered and mapped on a still frame from each plot (fig. 3). time and position of sightings of chicks (fledging or engaged in pre-fledging behaviour), including their use of nesting holes, were also recorded. by overlaying all this information, the number of active nests in each plot could be determined. results and discussion the video surveillance proved to be a useful method to estimate the density of active nests. in 2012, 17 active nests were determined based on feeding events (adult entrances) and 17 individual large (20 d+) chicks were recorded. of these chicks, actual fledging of 10 was recorded, four were still in the nest when the study terminated and three disappeared (fledged figure 2. an example of approach routes to the nest of five food-carrying little auks from plot mv, qoororsuaq, north-west greenland, during a 24-h video recording on 9 august 2013. plot border shown in black. positions of nests are shown with large yellow dots including nest numbers; otherwise, larger unnumbered dots show landing place, smaller dots positions where the bird stopped briefly en route to the nest. the birds from nest 9 and nest 6.1 often used the same entrance. the figure is based on 27 feedings in total: seven feedings at nest 11 (blue), six at nest 9 (white), three at nest 8 (red), five at nest 6.1 (green) and six at nest 5 (yellow). polar research 3 or died) during the daytime on 10 august when the video camera was not on. in 2013, 15 active nests were identified and 10 large chicks were recorded. the breeding season of 2013 occurred three days later than in 2012 and the actual fledging of only one chick was recorded, the remaining chicks still being in the nest when the study was terminated. the resulting densities of active nests for the two plots in 2012 and 2013 ranged between 1.63 nests/m2 (11 active nests mv plot 2012) and 1.06 nests/m2 (five active nests vv plot 2013; see table 1). these densities should be regarded as a minimum estimate of breeding density as the study took place at the very end of the breeding period and does not provide information on failed breeding attempts earlier in the season. given the timing of the study, the nest densities found should correspond closely to the productivity of fledglings per m2. the high breeding densities found in this study cannot be directly extrapolated to all the little auk colonies mapped in the thule area, which are distributed across a range of 325 km, have different scree morphology and therefore probably different little auk breeding densities. a detailed mapping of colony geomorphology along with a substantial number of density plots will be needed to produce an estimate that is appropriate for the whole thule area. analysing the video footage was time-consuming (ca. 40 min viewing/1 h footage). the main difficulty arose from the fact that many birds used more than one entrance to the nest or, in a few cases, that two pairs used the same surface entrance (mv plot 2013). for example, in the mv plot in 2013, holding 10 pairs, 60% of the nests had two or three entrances, and 70% had two or three exits. assuming that every entrance used by a chick-feeding adult represented an active nest would have yielded an overestimation of the true number of active nests by 70%. to reduce the time consumption of footage analysis, the video camera should have a good viewing angle, preferably from uphill down on the study plot, and as many birds as possible should be individually marked with picric acid. the emergence of chicks from the nests about 1 – 3 days before fledging can confirm the presence of active nests. it is therefore important that the video surveillance includes the pre-fledging period. in addition to nest density, the analysis of feeding events during three days of continuous video recording in 2013 provided detailed information on the diurnal pattern of chick feeding and chick-feeding rates (fig. 4). on average, we found 9.1 feedings/ chick/day (n = 8 pairs, 3 × 24 h, 219 feedings) during this late stage of the chick-rearing period, when females have reduced their feeding rate (fig. 5) before the chick fledges and leaves the colony with the male parent (stempniewicz 2001). still, our feeding rate corresponds well with feeding rates published for breeding colonies around the greenland sea, which range from 7.4 to 9.7 feedings/chick/day (welcker, harding et al. 2009). information on chick-feeding rates, likely reflecting marine feeding opportunities, can be a valuable monitoring parameter for little auk colonies, especially combined with the use of chick figure 3. video still frame of plot mv, 2013. the active nest holes (yellow dots) and the different supplementary entrance/exit holes (light yellow dots) used are linked with light yellow lines. the birds from nests 2 and 12 and from nests 6 and 9 often used the same entrance. table 1. the number and density of active little auk nests at the end of the breeding season in the two study plots at qoororsuaq, north-west greenland, 2012–13. the nest density corresponds closely to the productivity of fledglings per square metre. mv plot vv plot year nest (n) nest/m2 nest (n) nest/m2 2012 11 1.63 6 1.27 2013 10 1.48 5 1.06 mean 1.56 1.17 4 a. mosbech et al. meals as (selective) samples of pelagic zooplankton (welcker, harding et al. 2009; welcker, steen et al. 2009; frandsen et al. 2014). chick-feeding rates of little auks have often been established by means of direct, 24-h observations of study plots with individually marked birds in the field or by analysing data from temperature, time–depth or gps loggers deployed on breeding adults. while the former method may be prone to observer fatigue and missing observations, the latter approach has recently been criticized for yielding biased results as the birds may be affected by the burden of the logger (kidawa et al. 2012). our video surveillance method does not suffer from these shortcomings and may be a more suitable alternative monitoring technique. the breeding density estimates from qoororsuaq (table 2) correspond well with the density estimates obtained from gulliksenfjellet, svalbard, using the mark–resight methodology (isaksen & bakken 1995). somewhat lower densities have been found with the mark–resight methodology in four other localities in north-west and north-east greenland and svalbard (table 2). the reason we abandoned the mark–resight methodology in qoororsuaq was that breeding birds (birds with brood patch/filled gular pouch) marked in a figure 4. the diurnal feeding pattern in plot mv during the late chick-rearing period, 8 – 10 august 2013 (eight pairs, 3 × 24 h, 219 feedings). figure 5. the frequency distribution of feeding intervals of sexed adults (three pairs) during the late chick-rearing period (8 – 10 august 2013, 3 × 24 h) in plot mv (n = 100). polar research 5 study plot were observed on rocks far from the plot, violating the assumption of the mark–resight model. seabird behaviour can differ between colonies (e.g., jakubas & wojczulanis-jakubas 2011) and we have no reason to believe that the mark–resight estimates given for the other localities in table 2 are biased. where applicable, the two methods could be supplementary. direct nest counts have been used for estimating nest density in two studies (table 2), but the reliability of this method is challenged by the location of many of the nests deep below the stones. conclusion establishing integrated ecosystem monitoring programmes to support adaptive management is needed in the rapidly changing high-arctic environment and is recommended by arctic council working groups such as conservation of arctic flora and fauna and protection of the arctic marine environment. in this context, the video surveillance method presented here can be a valuable element in monitoring little auk colonies, especially as the technological development of video cameras leads to improvements of storage, battery capacity and optical resolution. a monitoring programme combining this method with analysis of little auk chick meals (zooplankton “samples”) and studies using time–depth and gps loggers on foraging birds will allow assessment of how successfully little auks adapt foraging behaviour to a high-arctic environment under change (see, e.g., jakubas et al. 2016). acknowledgements we want to acknowledge the base commander at thule air base for permission to use the base, and the danish liaison officer and greenland contractors, especially tony rønne pedersen, hans otzen and erland søndergård, for extensive logistic and practical help. molecular sexing was carried out by liselotte wesley andersen. flemming merkel is acknowledged for assistance with video camera set-up and david boertmann, nicholas p. huffeldt and allan j. kristensen for assistance in the field. two anonymous reviewers provided useful comments. disclosure statement no potential conflict of interest was reported by the authors. funding the fieldwork was undertaken as part of the baffin bay environmental study program 2011–14 conducted by the danish centre for environment and energy, aarhus university, and the greenland institute of natural resources funded by the bureau of minerals and petroleum, greenland government. the north water project funded by the velux foundations and the carlsberg foundation covered part of the analytical and writing costs. references arctic council expert group on ecosystem-based management 2013. ecosystem-based management in the arctic. tromsø: arctic council. barrett r.t., chapdelaine g., anker-nilssen t., mosbech a., montevecchi w.a., reid j.b. & veit r.r. 2006. seabird numbers and prey consumption in the north atlantic. ices journal of marine science 63, 1145–1158. boertmann d. & mosbech a. 1998. distribution of little auk (alle alle) breeding colonies in thule district, northwest greenland. polar biology 19, 206–210. egevang c., boertmann d., mosbech a. & tamstorf m.p. 2003. estimating colony area and population size of little auks alle alle at northumberland island using aerial images. polar biology 26, 8–13. evans p.g.h. 1981. ecology and behaviour of the little auk alle alle in west greenland. ibis 123, 1–18. fort j., moe b., strøm h., grémillet d., welcker j., schultner j., jerstad k., johansen k., phillips r.a. & mosbech a. 2013. multicolony tracking reveals potential threats to little auks wintering in the north atlantic from marine pollution and shrinking sea ice cover. diversity and distributions 19, 1322–1332. frandsen m.s., fort j., rigét f.f., galatius a. & mosbech a. 2014. composition of chick meals from one of the main little auk (alle alle) breeding colonies in northwest greenland. polar biology 37, 1055–1060. frederiksen m., falk k., huffeldt n.p., johansen k., labansen a.l., linnebjerg j.f., merkel f. & mosbech a. 2014. seabird baseline studies in baffin bay 2008-2013. colony-based fieldwork at kippaku and apparsuit, nw greenland. scientific report from dce – danish centre for environment and energy 110. aarhus: aarhus university, danish centre for environment and energy. table 2. overview of published nest density estimates from little auk colonies. locality density (nest/m2) range breeding stage boulder diameter method authors qoororsuaq, nw greenland 1.37 1.06 – 1.63 late chick-rearing 30 – 40 cm videocam: feeding events this study hakluyt, nw greenland 0.73 0.5 – 1.3 early–late chickrearing ? mark–resight kampp et al. (2000) horsehead, nw greenland 0.25 na ? ? nest count evans (1981) kap høegh, ne greenland 0.7 na na ? mark–resight kampp et al. (1987) gulliksenfjellet, svalbard 1.5 1.2 – 1.9 early chick-rearing 32 – 43 cm mark–resight isaksen & bakken (1995) bjørndalen, svalbard 0.5 0.2 – 0.5 incubation 25 cm mark–resight isaksen & bakken (1995) ariekammen, svalbard 0.6 0.5 – 0.7 ? ? nest count stempniewicz (1981) 6 a. mosbech et al. grémillet d., fort j., amélineau f., zakharova e., le bot t., sala e. & gavrilo m. 2015. arctic warming: nonlinear impacts of sea-ice and glacier melt on seabird foraging. global change biology 21, 1116–1123. irons d., petersen a., anker-nilssen t., artukhin y., barrettt r., boertmann d., gavrilo m.v., gilchrist g., hansen e.s., hario m., kuletz k., mallory m., merkel f., mosbech a., labansen a.l., olsen b., österblom h., reid j., robertson g., rönkä m. & strøm h. 2015. circumpolar seabird monitoring plan. caff monitoring report 17. akureyri: conservation of arctic flora and fauna international secretariat. isaksen k. & bakken v. 1995. estimation of the breeding density of little auks (alle alle). in k. isaksen & v. bakken (eds.): seabird populations in the northern barents sea. source data for the impact assessment of the effects of oil drilling activity. norsk polarinstitutt meddelelser 135. pp. 37–47. tromsø: norwegian polar institute. jakubas d. & wojczulanis-jakubas k. 2011. subcolony variation in phenology and breeding parameters in little auk alle alle. polar biology 34, 31–39. jakubas d., wojczulanis-jakubas k., boehnke r., kidawa d., błachowiak-samołyk k. & stempniewicz l. 2016. intra-seasonal variation in zooplankton availability, chick diet and breeding performance of a high arctic planktivorous seabird. polar biology 39, 1547–1561. kampp k., falk k. & egevang pedersen c. 2000. breeding density and population of little auks (alle alle) in a northwest greenland colony. polar biology 23, 517–521. kampp k., meltofte h. & mortensen c.e. 1987. population size of the little auk alle alle in east greenland. dansk ornitologisk forenings tidsskrift 81, 129–136. karnovsky n., brown z., welcker j., harding a., walkusz w., cavalcanti a., hardin j., kitaysky a., gabrielsen g. & grémillet d. 2011. inter-colony comparison of diving behavior of an arctic top predator: implications for warming in the greenland sea. marine ecology progress series 440, 229–240. kidawa d., jakubas d., wojczulanis-jakubas k., iliszko l. & stempniewicz l. 2012. the effects of loggers on the foraging effort and chick-rearing ability of parent little auks. polar biology 35, 909–917. meltofte h. (ed.) 2013. arctic biodiversity assessment. status and trends in arctic biodiversity. akureyri: conservation of arctic flora and fauna international secretariat. stempniewicz l. 1981. breeding biology of the little auk, plautus alle in the hornsund region, sw spitsbergen. acta ornithologica 18, 141–165. stempniewicz l. 2001. little auk (alle alle). in m. ogilvie (ed.): bwp update. vol. 3. the journal of the birds of the western palearctic. pp. 175–201. oxford: oxford university press. welcker j., harding a.m.a., karnovsky n.j., steen h., strøm h. & gabrielsen g.w. 2009. flexibility in the bimodal foraging strategy of a high arctic alcid, the little auk alle alle. journal of avian biology 40, 388–399. welcker j., steen h., harding a.m.a. & gabrielsen g.w. 2009. sex-specific provisioning behaviour in a monomorphic seabird with a bimodal foraging strategy. ibis 151, 502–513. polar research 7 abstract introduction material and methods results and discussion conclusion acknowledgements disclosure statement funding references the storfjorden polynya: ers-2 sar observations and overview jorg haarpaintner persistent polynyas have been observed over several winters in storfjorden. situated between spitsbergen and barentsgyaledge@ya in the south of the svalbard archi pelago. polynyas are in general active regions with respect to ocean-atmosphere heat exchange, presenting strong convection phenomena and as such being involved in important water mass formation and having an impact on the marine ecosystem. hydrographic observations have revealed very dense (cold and saline) brine-enriched bottom waters leaving the continental shelf as gravity driven plumes into the deep sea west of spitsbergen. satellite observations, using ers-2 sar imagery, reveal the evolution of the storfjorden polynya during winter 1997/98. after forming a complete ice cover until mid-january, storfjorden responds dynamically to northerly winds by opening a large latent heat polynya. it occupies at its largest extent a region of up to 6000 km2 of open water, thin ice and brash ice. comparable i n size to other large arctic polynyas, the storfjorden polynya might have the same or even greater importance i n the thermohaline circulation and bottom water mass formation. ice production is estimated at 30 km' i n storfjorden, rejecting around 700 mt (megatons) of salt that can raise the salinity i n storfjorden by 0.9-1.0 psu. first studies and the winter 1997/98 evolution of this polynya are presented i n this paper. j. haurpuintner, nont3egiun polar institute, polrir environniental centre, n-9296 trorns@, n ~ m ~ l i y . introduction first ers-2 sar (synthetic aperture radar) observations from storfjorden on 6 march 1996 revealed the presence of a half-moon shaped polynya between agardhbukta and freemansundet (fig. la). polynyas and leads contribute inten sively to the ocean-atmosphere heat exchange and important convection phenomena take place i n these regions because of densification of the water by strong cooling and brine rejection during freezing (smith et al. 1990; gawarkiewicz & chapman 1994). a storfjorden polynya is the most likely source for brine-enriched shelf water. which has been observed by midttun (1983, quadfasel et al. (1988) and schauer (1995) in storfjorden and storfjordrenna. characteristics of this water mass are temperatures near freezing point and salinities greater than 34.75 psu. quadfasel et al. (198x) even measured 35.4psu i n 1986. flowing out from storfjorden as a gravity driven plume over the continental shelf into the deep sea west of spitsbergen (jungclaus et 31. 1995), the brine enriched shelf water has an important role in the global thermohaline circulation (rudels 1995). it is therefore of great interest to observe by satellite the evolution of the storfjorden polynya over the entire winter to estimate the brine production. in the first section, storfjorden and the regional ice conditions are presented. the evolution of the ice conditions during winter 1997/98 is described next, with an estimate of the ice production, and thus the salinity increase due to salt rejection. an attempt at automatic classification is made in the third section, before concluding this paper. storfjorden and regional ice conditions storfjorden (big fiord), situated between spits bergen and edgegydbarentsgya in the south-east of the svalbard archipelago, is not actually a true fiord. the northern part of storfjorden is breached by two shallow straits about 20 in deep (fig. la): in the north, heleysundet, between spitsbergen and barentsgya; and in the east, freemansundet, haarpaintnrr 1999: pokir research 18(?). 175-1 x2 i75 f i g . 1. (a) the svalbard archipelago. with the position of the ers-2 sar images framed. (b) superposition of the ers-2 sar images from 5 march 1998. (original data ,i: esa 1998). distributed by eurimage [tss], orbit 15021, track 137, frames 2007 and 2025) with the storfjorden hathymetry. it shows the horseshoe-shaped storfjorden polynya 0, extending southward from a semicircle approximately hounded by agardhhukta and diskohukta to the sill 0 at 77”. 0 indicates pdst ice regions in the north and in the west of storfjorden. i76 the storfjorden polynya: ers-2 s a r observations dividing barentssya and edgecbya. strong currents of 4-5 m/s and 2 m / s in heleysundet and free mansundet, respectively, have been observed (norges sjskartverk 1988). tidal models have shown that these currents might result from a half phase shift of the tides between inner storfjorden and the northern barents sea around kong karls land (gjevik et al. 1994). the northern part of storfjorden is shallower than 80 m with the exception of two ca. 120m depressions at the north-west; these can trap some dense waters. a depression is located i n the centre of storfjorden, at about 77"30'n 19"e, with a maximum depth of 190 m. it is separated from storfjordrenna by a sill (fig. ib) of about 120m depth at 77". this opening is bounded by storfjordbanken (shelf about 20 m deep) to the east, the spitsbergen coast and a 40 m deep ridge to the west. storfjordrenna is the extension of this connection from stor fjorden to the deep sea west of spitsbergen. figure ib shows a typical view of the stor fjorden polynya and ice conditions in late winter ( 5 march 1998) after two weeks of north-easterly winds. the satellite image is superposed on a bathymetry map of the barents sea. the fast ice boundary at the spitsbergen coast closely follows the l 0 0 m depth contour. north of an imaginary line between freemansundet and agardhbukta, a solid fast ice cover about 120cm thick was measured during field work in april 1998. at its largest extent, the polynya spreads out as far as the sill at 77"n. extending southward from a semi circle roughly bounded by agardhbukta, free mansundet and diskobukta. we assume katabatic winds are responsible for the bright areas visible i n fig. 2 . the approximate size evolution of the storfjorden polynya during winter 1997/98 estimated from 13 ers-2 s a r images (dashed line) and the component (solid line) from the norwegian weather station 6mo moo north/south wind velocity -4000 1 i] situated on hopen island. iim f 1000 0 diskobukta inside the polynya; these winds rough en the sea surface with capillary waves. the storfjorden polynya is a wind-driven latent heat polynya opening under northerly winds. the strong tidal current through freemansundet prob ably helps by weakening the ice cover and leading to the break-off of ice floes from the northern fast ice. these ice floes and fields are carried south wards by stress from northerly winds. during winter. the pack ice limit in the barents sea is mostly between 75'" and 76"n, i.e. south of storfjorden and blocking the ice drift out of it. thus, an accumulation of ice floes must take place, creating an ice reservoir that can refill storfjorden under southerly wind conditions. large quantities of ice floes drift northwards around spitsbergen's ssrkapp (south cape) with the west spitsbergen current. which might partly have their origin in storfjorden, signifying a net freshwater export. 1997198 winter survey of the storfjorden polynya the satellite survey by ers-2 sar imagery over the winter 1997/98 gives a first rough estimate of the evolution of the extent of the storfjorden polynya (fig. 2 ) . in total, 27 ers-2 sar images have been acquired from the end of november 1997 until the end of april 1998, comprising the basis for this study. two images form each view over storfjorden, giving the ice condition on 13 dates. one single image from 27 march 1999 is not presented. three ers-2 satellite flight paths have haarpaintner 1999: polur resrurch 18(2), 175-182 177 f i g . 3. weekly averaged north/ south wind component and air temperature data from the norwegian meteorological station at hopen and, until 4 april 1998, from an automatic weather station at kapp dufferin on the west coast of storfjorden. initially 3 in high, the automatic weather station was damaged soon after it was established. therefore, no wind data have been acquired and the air temperature has been measured at ground level. the temperature is on average 6’c higher on hopen than at kapp dufferin. been used to acquire these images. for the polynya size estimate, we only considered the region that is covered by all tracks, covering about 10 000 km2 of storfjorden. the area of interest is indicated in fig. i and in detail in fig. 4. the north-south wind velocity component is also presented in fig. 2 and correlates well with the opening and closing of the polynya. wind and air temperature (fig. 3) have been acquired from hopen, a station of the norwegian meteorological institute (dnmi). an automatic weather station at kapp dufferin indicates temperatures in storfjorden on average 6°c colder than on hopen over the whole winter. however, this weather station was badly damaged shortly after its set-up, and thereafter measured the air temperature close to the ground. therefore, for our ice calculation we assume an air temperature in storfjorden only 2 ’ c colder than on hopen. northerly winds are always correlated to colder temperatures. every eks-2 sar view has been interpreted visually using four time series that are part of our image set and relying on the knowledge of the region acquired during field work. two views separated by three days constitute one time series. it is relatively straightforward to divide stor fjorden into three regions: fast ice, polynya and pack ice. figure 4 shows how the ice cover on 5 march 1998 has been segmented into these three classes (see fig. i b for comparison). the fast ice region, identified by the fact that it does not show any dynamics in time series, can be distinguished very easily from a polynya region, which presents a wide range of backscatter coefficients and no obvious structures of ice floes. pack ice, by contrast, has a structure of big ice floes and a quite homogeneous backscatter coefficient. a distinction between fast and pack ice is only possible when the dynamics of the pack ice are obvious in the time series. the wide range of backscatter coefficients inside the polynya is due to several causes. under calm conditions, thin nilas and open water have a very low backscatter coefficient. higher backscatter coefficients may be due to the effect of wind on open water, and frost flowers, which can form at the surface of thin ice by condensation and freezing of water vapour (ulander et al. 1995). in addition. young new ice is very sensitive to movement induced by wind and currents and piles up in pressure ridges and/or breaks into flows, which can slide partly over each other so-called rafting. thus, the polynya region includes open water, frazil ice, nilas and ridged and rafted young ice. the separation of young ice and water inside the polynya is difficult with sar alone, but is possible by modelling the frazil ice production and assuming its accumulation at the lee side of the polynya. sar images from early winter (mid-november until mid-january) show that until the end of november only unstructured ice (pancake and frazil ice) is present in storfjorden. in december, some ice floes are initially transported into stor fjorden through freemansundet and heleysundet. until mid-january storfjorden is almost totally ice-covered with large areas of fast ice in the north and at the spitsbergen coast, leaving open a coastal polynya in diskobukta, west of e d g e ~ y a . a first break-off of the ice cover happens at the end of january 1998 north-east of agardhbukta after three weeks of northerly winds of about 4-6 d s , opening a polynya of about 2000 km’. it closes again with freezing and southerly winds until mid february. an image from 17 february 1998 shows 178 the storfjorden polynya: ers-3, sar observations has not yet been driven away. from this time on, this break-off line is visible and remains stationary during the rest of the winter. the size of the polynya is then probably only dependent on wind direction and wind speed, and of course ice formation (willmott et al. 1997). the peak of the polynya size in the beginning of march was preceded by two weeks of north-easterly winds of about 4-8 d s . it seems that at the end of march, southerly winds filled storfjorden with first year ice in addition to newly formed ice. northerly winds opened the polynya again at the beginning of april. the automatic weather station at kapp dufferin gives us air temperature data between october 1997 and april 1998 (fig. 3) and shows that even very low temperatures (-30°c) cannot prevent the polynya from developing. at its largest extent, the polynya exposes an area of 6000 km2 of open water and thin new ice to very rough atmospheric conditions, resulting in large ocean atmosphere heat exchanges and ice formation (lepparanta 1993). hydrographic measurements (ctd) from april 1998 showed that the whole water column of storfjorden is near its freezing point ( < 1.85”c), and that there is no heat available from below which could prevent new freezing. during frazil ice formation around two-thirds of the salt is rejected instantly as brine (martin & kauffman 1981) and sinks down to the bottom where it forms brine-enriched shelf water. this fills the deep depression in storfjorden and later flows over the sill into storfjordrenna and the deep sea west of spitsbergen (jungclaus et al. 1995). haarpaintner et al. (unpubl. ms.) coupled these observations with polynya size and ice production models. they interpolated the polynya size estimates from sar using wind data and distinguished, inside the polynya, between thin ice and open water using pease’s approach (pease 1987) to frazil ice accumulation at the lee side of the polynya. these calculations suggest that an ice volume of about 30 km3 is produced in storfjorden between november 1997 and the end of may 1998, rejecting 700 mt (megatons) of salt. without advection, this could increase the salinity of the by 0.9-1 .o psu. about two-thirds of the entire ice volume form inside the polynya, which covers on average only 13% of storfjorden. maximum salinity measured in april 1998 in the centre of leads along the typical break-off line “agardhthe depression was 35.05 psu at the bottom freeman-diskobukta” of the polynya, but the ice (160 m depth) at freezing temperature (1.9”c), f i g . 4 . manual segmentation of the storfjorden ice cover (111 the ers-? sar image from 5 march 1998 (fig. i ) into three classes: fast ice. polynya and pack ice. the striped area i s not covered by all used satellite tracks and is therefore not considered for the polynya size estiniate. entire storfjorden water volume (7.5 x 10” m3) haarpaintner 1999: polar reselirch la(?), 175-132 179 giving a sigma-t, ct, of 28.22 kg.m-3. if we suppose an average salinity increase of 0.3 psu i n the water column, the rejected salt from the six winter months could enrich three times the volume of storfjorden, confirming the renewal time of two months for the entire storfjorden waters suggested by schauer (1995). sar imagery of sea ice and ice classification the sar (synthetic aperture radar) of the european satellite ers-2 is an active microwave sensor that emits a signal at 5.3 ghz (c-band) at 782 km altitude. it is independent of solar radia tion, penetrates clouds and has a resolution of 30 m. thus, it is a suitable instrument for remote sensing in the polar regions. the reflected (back scattered) signal from the ground. here mostly ocean and ice, is then received and by signal processing gives a grey level image of an area covering 100 x 100 km2. the images were de livered by the tromso satellite station i n full and low resolution format (fri and lri format). the resolution was reduced by averaging to 1000 x 1260 pixels per scene to eliminate the sar-specific speckle noise and for easier visual ization and handling. radar backscatter depends mostly on the surface roughness of the sea ice (carsey 1992). before freezing to a smooth ice cover, the backscatter coefficient may vary enormously from very dark grey level (low backscatter coefficient) for open water in absence of wind. to very bright (high backscatter coeffi cient) for wind roughened sea or ice crystals and frost flowers growing on thin ice (nilas). thin smooth ice has a very low backscatter coefficient, which will increase with ageing and deformation of the ice. with time the ice becomes thicker by continuous growth and often rougher due to compression, shear movements, rafting and rid ging. these signatures can be very clear on the sar image, but can also be very ambiguous, especially for very young ice and open water as explained above. from the tentative classification on the image from 6 march 1996, we sketched a possible evolution of the backscatter coefficient with ageing and freezing for first year ice (fig. 5 ) . i n calm wind conditions and calm sea, the large variation in the backscatter coefficient might be less than sketched or even absent during ice new ice wilh frost flowers n iii. -ia s -12 broken young ice ! /v ice thickness, fracture and friction increase first year ice ice age f i g . 5. sketch of a possible s a r backscatter coefficient variation versus ongoing ice formation and ageing. under rough wind conditions. the variation between open water and grey ice might be very strong. passing by a maximum backscatter coefficient. under calm conditions (no wind and waves), the variation could be minimal. formation. however, this evolution of the back scatter coefficient during ageing is dependent on ocean dynamics and weather and can therefore differ with region and time (steffen & heinrichs 1994). classification of sea ice by satellite and ice tracking is important in order to define the origin, age and type of ice (askne 1996; carsey 1992; kergomard et al. 1994; steffen & heinrichs 1994; sun 1996). the evolution of the backscatter coefficient is complex and highly variable, especially during ice formation (fig. 5 ) . this explains the different appearance i n brightness of the storfjorden polynya between 1996 (fig. 6a) and 1998 (fig. i). the first attempts to classify the storfjorden ice cover have been made on the sar image from 6 march 1996, when the polynya appeared as a bright region. this area of more than 1000 km2 has a very high backscatter coefficient. this strong signal might be either due to frost flowers growing at the surface by condensation and freezing of water vapour through very thin ice or due to wind roughened open water. we reduced the high resolution image to two images by taking for one the mean value and for the other one the variance of a 5 x 5 pixel window. then, using a two dimensional supervised classification, we arrived at a classified image presented i n fig. 6b. multi year ice is not very common in storfjorden, but early winter images show that some might be transported through the straits or around edgeoya. the ice classification is an attempt to sub-classify first year ice by sar imagery. the polynya is well defined, but a reliable ice type classification has 180 the storfjorden polynya: ers-2 sar observations need further investigation to improve ice classifi cation by sar imagery. fig. 6. (a) ers-2 sar observation of the storfjorden polynya on 6 march 1996 (original data (i, esa [1996], distributed by eurimage [tss]). the polynya has a very strong hackscotter coefficient. (b) first attempt at first y e u ice suh-classification using a two-dimensional supervised classification. not been achieved yet, even though it is possible to recognize different structures in the ice cover and especially to differentiate the northern fast ice from big ice floes south of the polynya. figure 1 shows that the situation in storfjorden can be very variable and that it is nearly impossible to differentiate individual ice floes in the southern part of the polynya, where brash ice, accumulation. rafting and ridging of thin ice strongly reflects the sar signal. thus, different ice type signatures discussion and conclusion the storfjorden polynya is probably the cause of the abundance of brine-enriched shelf water found in this area. satellite remote sensing techniques, such as synthetic aperture radar (sar) from the european earth remote sensing satellite ers-2, seem to be adequate tools for studying the extent and evolution of the polynya. first analyses of a data set comprising a large quantity of images give a good and precise overview of the winter evolution of the polynya, the ice conditions and the dynamics of the fiord. the polynya comprises, at its largest extent, a region of up to 6000 km2, which is comparable to other large polynyas already investigated in the arctic (smith et al. 1990). wind direction data from the norwegian meteorological station on hopen show that the opening of the storfjorden polynya is correlated with northerly winds, and closing with southerly winds. on account of this dynamic response to wind. it can be classified as a latent heat polynya. as defined in smith et al. (1990), in contrast to sensible heat polynyas that form due to heat fluxes from the ocean like up-welling of warmer water. the storfjorden polynya is responsible for the production of two-thirds of the total storfjorden ice volume of about 30km3. the 7 0 0 m t of rejected salt could raise the salinity of storfjorden by 0.9-1.0 psu. comparison between the hopen station and the automatic weather station at kapp duffenn shows that the temperature in storfjorden is some degrees colder than on hopen. further investigation of different ice type signatures on sar images is necessary to provide a reliable classification, which is important to calculate the heat exchange between the atmos phere and the ocean. nevertheless, classification by hand and eye is possible to some degree, depending on the kind of classes chosen. using a relatively large number of ers-2 sar images, including time series, we could with comparative accuracy distinguish three classes: fast ice, pack ice and polynya, as explained earlier, this rough classification should be reproducible, though regional knowledge and ground truthing make the task much easier. however, the problem is how informative is this classification regarding the haarpaintner 1999: polar research 18(2), 175-182 181 calculation of heat exchange between the ocean and the atmosphere and thus, for ice formation, i.e. what do we actually define as a polynya? in our case, the class of polynya is not only open water as some would define a polynya, but a region, showing high dynamics in time series, where no big ice floe structure is visible and presenting a wide range of backscatter levels. field work by helicopter showed that this region includes open water, brash ice and accumulation, ridging and rafting of thin ice. it is therefore important to verify remote sensing observations by modelling to accurately estimate the ice production. model ling the polynya size and the open water fraction shows that on average only 17% of the polynya is ice-free. winter hydrographic measurements are important to study water mass evolution over the year and to make the estimation of brine produc tion using sar possible in the future. an interesting approach in sea ice remote sensing is the superposition of bathymetry and sar satellite data to observe depth dependent ice and oceano graphic features. acknorcledgements. this work has been funded by grant contract nr. mas3-ct96-5036 from the european union under contract with the norwegian polar institute. ers-2 sar images were distributed by the t r o m s ~ satellite station and weather data from hopen by the norwegian meteorological institute (dnmi). the weather station at kapp dufferin has been financed by the university courses on svalbard (unis) and set up with the help of professor yngvar gjessing, nils nilson and associate professor peter m. haugan. field work in storfjorden was funded by the norwegian polar institute and unis and carried out together with dr. jean-claude gascard, dr. peter m. haugan, dr. vigdis tverberg and frank beuchel. the author is indebted to professor claude kergomard who initiated him to the subject in 1996. special thanks go to dr. w. paul budgell for supervision, advice and useful discussions. references askne, j. 1996 remote sensing of arctic sea ice. proceedings of the a c s y s conference on the dynamics of the arctic climate system. gothenburg, sueden, 7-10 november 1994. wmofld-no. 760. pp. 60-64. gothenburg: world meter ological organization. carsey. f. d. (ed.) 1992: microwave remote sensing ofsea ice. geophysical monograph 68. 462 pp. washington, d.c.: american geophysical union. gawarkiewicz, g. & chapman d. c. 1994: dense water formation on arctic shelves model tracks coastal ocean response to arctic ice conditions. oceuiuts 37(2). 14-16. gjevik, b., nest, e. & straume t. 1994: model simulations of the tides in the barents sea. j . geophys. res. 99(c2). 3337-3350. haarpaintner, j . . gascard, j . c. & haugan, p. unpubl. ms. ice and brine formation in storfjorden. jungclaus, j. h., backhaus, j. 0. & fohrmann, h. 1995: outflow of dense water from the storfjord in svalbard: a numerical model study. j . geophys. res. ioo(c12), 24.7 19-24.728, kergomard, c., gascard, j. c., fily, m., delacoun, c.. lefort, c. & darr, d. 1994: the transpolar ice drift north of fram strait studied from ers-i sar imagery. proceedings second ers-i sviposium: space at the service of our environment, hamburg, germany, 11-14 october 1993. e s a s p 361, pp. 263-267. noordwijk (the netherlands): european space agency. lepparanta, m. 1993: a review of analytical models of sea-ice growth. annos.-ocean 31(1), 123-138. martin, s. & kauffman, p. 1981: a field and laboratory study of wave damping by grease ice. j . glnciol. 27(96), 283-313. midttun, l . 1985: formation of dense bottom water in the barents sea. deep-sea res. 32(10). 1233-1241. norges sj~kartverk 1988: den iiorske los/arc/ic pilot: for ~,annsbeskrivelse/sailinr direclions, trirveller’.~ guide. vol. 7. svulbnrd and jan mayen. 420 pp. stavanger (norway): norwegian hydrographic service and norwegian polar institute. pease, c. h. 1987: the size of wind-driven coastal polynyas. j . geophys. res. 92(c7), 7049-7059. quadfasel. d.. rudels, b. & kurz, k. 1988: outflow of dense water from svalbard fjord into the fram strait. deep-sea res. 35(7). 1143-1 150. rudels, b. 1995: the thermohaline circulation of the arctic ocean and the greenland sea. philos. trans. r . soc. london, ser. a-math. 352( 1699). 287-299. schauer. u. 1995: the release of brine-enriched shelf water from storfjord into the norwegian sea. j. geophys. res. loo(c8). 16,015-16.028. smith, s . d., muench, r. d. & pease, c. h. 1990: polynyas and leads: an overview of physical processes and environment. j. geophys. res. 95(c6), 9461-9479. steffen, k. & heinrichs. j. 1994: feasibility of sea ice typing with synthetic aperture radar (sar): merging of landsat thematic mapper and ers 1 sar satellite imagery. j . geophys. res. 99(ci i ) , 22.4 13-22a24. sun, y. 1996: automatic ice motion retrieval from ers-i sar images using the optical flow method. inr. j . remote sens. / 7 ( l l ) , 2059-2087. ulander. l. m. h., carlstrom, a. & askne. j. 1995: effect of frost flowers, rough saline snow and slush on the ers-i sar backscatter of thin arctic sea-ice. inr. j . remorr sens. l 6 ( 1 7 ) . 3287-3305. willmott, a. j., maqueda. m. a. m. & darby, m. s. 1997: model for the influence of wind and oceanic currents on the size of a steady-state latent heat coastal polynya. j . phys. oceanogr. 27(10), 22562275. 182 the storfjorden polynya: ers-2 sar observations sediments of mis 5e age suggested by new osl dates from the skilvika section, west svalbard research note sediments of mis 5e age suggested by new osl dates from the skilvika section, west svalbard helena alexanderson a & jon y. landvikb adepartment of geology, lund university, lund, sweden; bfaculty of environmental sciences and natural resource management, norwegian university of life sciences, ås, norway abstract the sediment succession at skilvika, west svalbard, represents one of the key stratigraphic records of the late quaternary palaeoenvironments and glaciation history of the svalbard/ barents sea area. a formation of raised marine sediments, interfingering with and capped by glacial deposits of local origin, have previously been assumed to be of an early weichselian age, likely marine isotope stage (mis) 5c. here we present a new series of optically stimulated luminescence (osl) ages that suggest the events took place in mis 5e. this advocates a revision of the correlation with other key stratigraphic sites on svalbard. keywords arctic; mis 5; glaciation history; luminescence dating abbreviations mis: marine isotope stage od: overdispersion osl: optically stimulated luminescence tl: thermoluminescence introduction the identification, correlation and dating of raised marine deposits formed during times with substantial glacio-isostatic depression has been, and still is, key to the reconstruction of the palaeoenvironmental and glaciation history of the arctic (mangerud et al. 1998; alexanderson et al. 2014). although such sediments are readily identified on sedimentological grounds, the stratigraphic records are often fragmented, and correlation relies heavily on numerical dating. the svalbard–barents sea ice sheet is no exception, and our knowledge of its history prior to the last glacial maximum is largely based on information from a limited number of key stratigraphic sites in svalbard (mangerud et al. 1998). one of these sites is skilvika, on the southern shore of bellsund, west svalbard (77.5706°n, 14.4402°e; fig. 1, supplementary fig. s1), a site that has been investigated since the 1960s and most recently studied by landvik et al. (1992). its stratigraphic record contains three subglacial tills (formations 1, 2 and 5) and two marine-littoral units (formations 3, 4, 6 and 7; fig. 2), of which the uppermost till–marine succession (formations 5–7) was deposited during the late weichselian (landvik et al. 1992). this study focuses on dating formations 3 and 4, which represent a period of high relative sea level culminating with the advance of a local glacier. based on limited numerical dating, landvik et al. (1992) concluded a marine isotope stage (mis) 5c age, and the sediments have been correlated to the early weichselian phantomodden interstadial (ca. 100 kya; mangerud et al. 1998). however, this age was based only on few tl ages and mainly non-finite radiocarbon ages (table 1, fig. 2) (landvik et al. 1992). the sediments have been resampled, and here we present a series of 20 osl ages that confirm a mis 5 age of formation 3, but most likely mis 5e instead of mis 5c. methods samples were collected in opaque bags (1997) and in opaque plastic tubes (1999, 2015) and were prepared and measured at the nordic laboratory for luminescence dating (1997/98, 1999) and the lund luminescence laboratory (2015). quartz grains in a range of size fractions (table 2) were extracted by mechanical and chemical preparation. measurements were made on large aliquots in risø tl/osl readers and using single aliquot regeneration protocols (murray & wintle 2000; murray & wintle 2003) adapted for the samples based on dose recovery and preheat plateau tests. stimulation was with blue light for most samples but with green light for some of the samples analysed in 1998. as the measurements were made on large aliquots, final ages were calculated from the arithmetic mean dose of each sample (guérin et al. 2017). dose rate was determined by gamma spectrometry (murray et al. 1987) and by accounting for the contribution from cosmic contact helena alexanderson helena.alexanderson@geol.lu.se department of geology, lund university, sölvegatan 12, 223 62 lund, sweden supplementary data can be accessed here polar research 2018, vol. 37, 1503907 https://doi.org/10.1080/17518369.2018.1503907 © 2018 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0002-5573-1906 https://doi.org/10.1080/17518369.2018.1503907 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2018.1503907&domain=pdf radiation according to prescott & hutton (1994). water content was determined in weight percent from separate samples taken next to the main sample. for age calculation it was assumed that the sediments have been saturated 95% of the time since deposition and the remaining 5% had a water content similar to that which was measured at the time of sampling. this is based on the sediments having been below sea level or below at least partially warm-based ice for much of the time since deposition, and only recently exposed along a rapidly receding coastal cliff, melted (from permafrost) and drained. finite radiocarbon ages from previous studies were calibrated using oxcal 4.2 online (bronk ramsey 2009) with the marine13 calibration curve (reimer et al. 2013) and assuming δr = 20 ± 30 yr (mangerud et al. 2006). results osl ages from formation 3 range from 263 ± 48 ky to 66 ± 5 ky, while the single sample from the base of formation 7 is 21 ± 2 ky (table 2). two samples from formation 3 are considered outliers, likely because of significant incomplete bleaching during an event with high sedimentation rate (sample 15098 at 755 cm) and to a too high dose rate (sample 15099 at 840 cm), respectively. both these ages fall far outside two standard errors of the mean for all formation 3 ages and show a mismatch in the proportional relationship of dose to dose rate compared to the other samples. excluding these two ages, the formation 3 age range is 149 ± 17 ky to 90 ± 7 ky (mean 119 ± 5 ky, n = 18). nine samples have od values consistent with those of well-bleached multigrain aliquots (13 ± 7%; arnold & roberts 2009), while 14 samples have significantly positively skewed dose distributions (table 2). discussion the osl ages from formation 3 span a wide range, which at face value covers both mis 6 and mis 5 (supplementary fig. s2). the mean age, 119 ± 5 ky, falls within mis 5e (the last interglacial), but within errors overlaps the stadial mis 5d. also, the error associated with the mean age is likely underestimating the true uncertainty given the wide age range of all samples and the broad dose distributions of individual samples. the mean age is nevertheless older than the previous tl ages (105–90 ky) that led landvik et al. (1992) to prefer an early weichselian (mis 5c-b) age for formations 3 and 4, although not ruling out an eemian (mis 5e) age. however, considering the spread of osl ages (149–90 ky) as well as an apparent age overestimation of the holocene sample in formation 7 (fig. 2), we need to look into some factors that could affect the ages. arguments for both overand underestimation of age can be made, and here we will evaluate the main ones. the formation 7 sample (sample 15097 at 400 cm) can be used for some assessments, since it is from sediments that represent a similar depositional environment as formation 3 and for which we have several independent, finite radiocarbon ages from large mollusc samples. a common cause for luminescence age overestimation in depositional environments such as those at skilvika (glaciated landscape with high sedimentation rates) is incomplete bleaching, when the sediment is not completely reset by sunlight at the time of deposition (e.g., fuchs & owen 2008; thrasher et al. 2009). one way to assess incomplete bleaching is to compare to an independent age control. this is possible for formation 7, but not for formation 3. compared to the radiocarbon age (11.0–10.6 cal. ky bp; table 1), the osl age from formation 7 appears to be about 10 ky too old (21 ± 2 ky; table 2). this sample has a significantly skewed dose distribution (sk = 1.3) and a high overdispersion (od = 40 ± 6%), which may hint that incomplete bleaching is the cause of its age overestimation (wallinga 2002). however, since our data are based on large aliquots, dose-distribution statistics must be treated with considerable caution on account of the averaging that occurs among the many grains making up each aliquot (duller 2008). if we tentatively apply this reasoning to the formation 3 samples, we note that a majority of the samples are significantly positively skewed and/or have large od values (table 2), similar to the formation 7 sample. however, some of the skewness may for these higher-dose samples be due to the shape of the dose response curve (murray et al. 2002; murray & funder 2003), rather than due to figure 1. location map of skilvika, svalbard. for more detailed location see supplementary fig. s1 and landvik et al. (1992). 2 h. alexanderson & j.y. landvik incomplete bleaching. there are, nonetheless, also samples from formation 3 that are not significantly skewed and that have ods consistent with wellbleached material. by excluding assumed incompletely bleached samples (those with sk > 3σs and/or od > 35%; table 2) and by accounting for any curverelated skewness by using the median dose for age calculation as recommended by murray & funder (2003), the mean age becomes 118 ± 7 ky (n = 10). this is indistinguishable from the mean age for all samples (except 15097, −98), as based on the arithmetic mean dose. another way to evaluate bleaching is to compare ages from different grain-size fractions. as grains with different sizes rarely have exactly the same transport path before deposition (bleaching history), they figure 2. composite log with luminescence (ky) and radiocarbon ages (cal. ky bp except for non-finite ages, which are in ky bp) from this study and from landvik et al. (1992). the photograph shows the positions of samples taken in 1999 only; the 2015 samples are from ca. 10 m to the right on the photograph, while the samples collected in 1997 are from the same unit but elsewhere in the cliff section. for details on ages see tables 1–2, and supplementary fig. s2 for an age-depth plot. table 1. radiocarbon ages of mollusc shells and seaweed from skilvika, 14c ages were originally published by landvik et al. (1992) and calibrated in this study using oxcal 4.2 (bronk ramsey 2009) with the marine13 calibration curve (reimer et al. 2013). non-finite ages have not been calibrated. lab. id. formation species 14c age (yr bp) calibrated age range, 2s (cal. yr bp) calibrated age, median (cal. yr bp) t-6222 7 hiatella arctica 9920 ± 90 9164–8675 8912 ± 128 t-5998 7 mya truncata 10 260 ± 110 9802–9042 9363 ± 190 t-5997 7 hiatella arctica 11 230 ± 120 11 020–10 565 10 773 ± 114 t-6000 6 nuculana pernula 12 570 ± 160 12 842–11 703 12 196 ± 287 ua-280 6 nuculana pernula 12 830 ± 210 13 296–11 955 12 624 ± 361 t-5993 4 hiatella arctica, macoma calcarea >45 500 t-5996 3 macoma calcarea >49 700 t-5994 3 seaweed 43 600 ± 1400/1200 47 731–42 601 44 912 ± 1340 t-5796 3 hiatella arctica 47 500 ± 2900/2100 47 630– ± – t-5795 3 hiatella arctica >51 700 t-5999 3 hiatella arctica, mya truncata >47 900 polar research 3 will likely not give the same age unless bleaching was efficient in the sedimentary environment (e.g. fuchs et al. 2005). three of our samples have been analysed with different grain sizes, ranging from 63–90 µm to 300–500 µm, and all three show agreement within error between fractions (table 2). this would support that bleaching has been sufficient. systematic age underestimation by 5–10% has been shown to occur for quartz osl ages from eemian deposits (murray & funder 2003) although the causes are not entirely understood. we cannot evaluate this factor for our data set specifically. also, information from osl ages from sediments correlated to the eemian elsewhere in svalbard is inconclusive as there are indications both of some age underestimation (alexanderson et al. 2013) and of no apparent underestimation (alexanderson et al. 2011; alexanderson et al. 2018). generally, there is a wide spread in ages for these sediments, which may be due to incomplete bleaching, poor luminescence characteristics or other causes, and which prevents resolving the age of the events in detail. age overor underestimation could also be caused by an incorrectly assumed water content, which would affect the average dose rate. if too high water content has been assumed, the dose rate will be too low and the age correspondingly too high, and vice versa. in this case, we have assumed a water content for our samples that is fairly close to saturation, i.e. almost as high as possible for these sediments. if this is too high compared to the true average water content since the time of deposition, the ages are too old. if the holocene sample 15097 from formation 7 is taken as an example again, and its water content is lowered to be equal to that at the time of sampling (12%), or even to the extreme of zero, only slightly younger ages of 19 ± 2 ky or 17 ± 2 ky, respectively, are produced. this significant overestimation of the true age leads us to conclude that variation in water content cannot explain the whole age overestimation for this sample at least. lowering the water content to present-day levels in late summer (7–17%) for the formation 3 samples results in an age range of 142–84 ky. with a mean age of 104 ± 4 ky, this would move the deposition of formation 3 to the early weichselian mis 5d/5c transition. however, we argue that the present water content should be considered a minimum and that the true average water content (and, therefore, age) must have been higher for most of the duration. from sedimentological and microfaunal evidence, we know that the dated sediments were deposited during a high relative sea-level event, with relatively open and saline marine conditions similar to today or slightly colder (landvik et al. 1992; lycke et al. 1992). this environment could represent either interstadial or non-climatic optimum (i.e., early or late) interglacial conditions, and so cannot be used to distinguish between mis 5e and 5c at this site. the proglacial deposit of formation 4, interpreted as resulting from a local glacier advance during a continued interstadial high-stand (landvik et al. 1992), could also reflect a local ice flow style during deglaciation (landvik et al. 2014). as discussed above, the spread in ages as well as the large uncertainty of individual ages prevents a precise age determination of formation 3, and both mis 5e and 5c are within the possible age range. table 2. osl data including age in kiloyears (ky), dose in gray (gy) and number (n) of aliquots accepted of the total number measured as well as sediment water content (w.c.) in weight percent. samples are sorted in order of depth. lab. no depth (cm) grain size (µm) age (ky) mean dose (gy) median dose (gy) ska odb (%) n/total dose rate (gy/ky) w.c. (%) formation 7 lund 15097 400 180–250 21 ± 2 21.4 ± 1.8 19.3 1.3 40 30/48 1.03 ± 0.05 25 formation 3 risø 993711 740 90–150 141 ± 11 142.4 ± 8.2 135.9 0.7 22 20/21 1.01 ± 0.05 30 risø 993711 740 250–500 147 ± 12 139.5 ± 8.1 142.9 –0.1 32 26/27 0.95 ± 0.05 30 risø 983701 745 106–212 145 ± 10 135.9 ± 5.7 141.2 –0.1 15 19/20 0.94 ± 0.05 24 risø 993710 750 90–150 141 ± 11 148.1 ± 8.2 137.2 0.6 21 20/21 1.05 ± 0.06 32 lund 15098 755 180–250 263 ± 48 272.2 ± 47.6 210.7 2.1 59 19/30 1.03 ± 0.05 18 risø 983703 800 106–300 123 ± 11 98.2 ± 5.5 91.5 0.6 19 16/20 0.80 ± 0.06 24 lund 15099 840 180–250 66 ± 5 94.9 ± 4.9 91.6 1.1 16 22/24 1.43 ± 0.06 25 risø 993709 850 90–150 114 ± 8 127.3 ± 4.9 122.9 –0.5 16 21/21 1.12 ± 0.06 24 risø 993708 880 90–150 99 ± 7 122.2 ± 5.4 112.4 0.8 15 19/21 1.24 ± 0.06 27 risø 993707 910 90–150 110 ± 7 129.2 ± 5.7 125.0 1.2 14 19/21 1.17 ± 0.05 24 risø 993707 910 300–500 107 ± 10 116.9 ± 9.3 112.9 0.3 62 26/27 1.10 ± 0.06 24 lund 15100 965 180–250 120 ± 10 99.8 ± 6.7 94.9 2.1 26 22/24 0.83 ± 0.04 27 risø 993706 970 90–150 109 ± 7 124.7 ± 4.5 117.3 1.5 8 15/15 1.14 ± 0.05 26 risø 993705 995 90–150 99 ± 6 132.0 ± 5.1 124.4 1.0 9 15/15 1.33 ± 0.06 29 risø 993704 1020 90–150 121 ± 9 139.5 ± 8.3 131.8 2.7 15 14/15 1.15 ± 0.05 27 risø 993703 1050 63–90 138 ± 11 159.1 ± 9.3 149.0 1.5 17 15/15 1.15 ± 0.05 21 risø 993703 1050 300–500 149 ± 17 158.7 ± 16.0 145.0 0.9 57 25/27 1.06 ± 0.06 21 risø 993702 1080 90–150 99 ± 9 98.3 ± 7.2 95.2 0.0 43 20/21 0.99 ± 0.05 30 risø 983702 1100 106–212 100 ± 7 115.2 ± 4.1 110.1 0.5 24 51/57 1.15 ± 0.07 24 risø 993701 1120 90–150 90 ± 7 99.8 ± 6.2 107.2 0.0 35 27/39 1.11 ± 0.05 24 askewness (sk) is considered significant if it is larger than the standard error of skewness σs, which is approximated by σs = √(6/n) (tabachnick & fidell 1996). ba measure of the variance that is larger than that expected from measurement uncertainty. a value of 13 ± 7% is considered to be consistent with well-bleached large aliquots (arnold & roberts 2009). 4 h. alexanderson & j.y. landvik however, assuming the sediments were sufficiently bleached, the mean age places the deposition in mis 5e. summary and conclusions twenty new osl ages place the raised marine deposits of formation 3 at skilvika, west svalbard, in the mis 5. if two unreliable ages are excluded, the mean age of the depositional event is 119 ± 5 ky (n = 18), which at face value is in the later part of mis 5e, the last interglacial. this is older than previously suggested by landvik et al. (1992), who placed formation 3 in mis 5c, although they did not exclude an eemian (mis 5e) age. our interpretation is based on the assumptions that the sediments were sufficiently bleached at the time of deposition and that they have been close to (water) saturation since that time. sufficient bleaching of formation 3 sediments is mainly supported by the agreement of ages between different grain sizes from the same samples. however, the age range of the 18 samples is large (149–90 ky) and the dose distributions of individual samples are broad, which gives the mean age a larger uncertainty than the ± 5 ky indicated by its numerical standard error. with this in mind, and considering the possibility of incomplete bleaching in the order of ca. 10 ky as indicated by a single osl age from the independently dated formation 7, we cannot completely rule out an early weichselian interstadial (mis 5c) age of formation 3. however, as argued above, we prefer the older age (mis 5e) as the most conservative conclusion based on the data. consequently, the formation 4 glacial deposit (fig. 2) probably reflects a local ice flow style (landvik et al. 2014) during deglaciation, rather than an advance of a local glacier as previously assumed (landvik et al. 1992). a mis 5e age also means that skilvika is added to the group of sites in svalbard with preserved eemian deposits (kapp ekholm, leinstranda, kongsfjordhallet, poolepynten), supporting the revised correlation scheme of late quaternary key stratigraphic sites on svalbard suggested by alexanderson et al. (2018). geolocation: 77.5706°n, 14.4402°e acknowledgements all sampling was performed during university centre in svalbard ag332/832 excursions, and benefited from assistance by students and teachers. andrew murray and the staff at the nordic laboratory for luminescence dating have provided advice on sampling and data analysis, as well as carried out measurements of most samples. constructive comments on the manuscript were received from anna hughes and teena chauhan. disclosure statement no potential conflict of interest was reported by the authors. funding dating of the 1997 and 1999 samples were made possible by a research grant from the university centre in svalbard to jyl. orcid helena alexanderson http://orcid.org/0000-0002-55731906 references alexanderson h., backman j., cronin t.m., funder s., ingólfsson ó., jakobsson m., landvik j.y., löwemark l., mangerud j., märz c., möller p., o’regan m. & spielhagen r.f. 2014. an arctic perspective on dating mid-late pleistocene environmental history. quaternary science reviews 92, 9–31. alexanderson h., henriksen m., ryen h.t., landvik j.y. & peterson g. 2018. 200 ka of glacial events in nw svalbard: an emergence cycle facies model and regional correlations. arktos 4(3), doi: 10.1007/s41063-018-0037-z. alexanderson h., ingólfsson ó., murray a.s. & dudek j. 2013. an interglacial polar bear and an early weichselian glaciation at poolepynten, western svalbard. boreas 42, 532–543. alexanderson h., landvik j.y. & ryen h.t. 2011. chronology and styles of glaciation in an inter-fjord setting, northwestern svalbard. boreas 40, 175–197. arnold l.j. & roberts r.g. 2009. stochastic modelling of multi-grain equivalent dose (de) distributions: implications for osl dating of sediment mixtures. quaternary geochronology 4, 204–230. bronk ramsey c. 2009. bayesian analysis of radiocarbon dates. radiocarbon 51, 337–360. duller g.a.t. 2008. single-grain optical dating of quaternary sediments: why aliquot size matters in luminescence dating. boreas 37, 589–612. fuchs m. & owen l.a. 2008. luminescence dating of glacial and associated sediments: review, recommendations and future directions. boreas 37, 636–659. fuchs m., straub j. & zöller l. 2005. residual luminescence signals of recent river flood sediments: a comparison between quartz and feldspar of fineand coarsegrain sediments. ancient tl 23, 25–30. guérin g., christophe c., philippe a., murray a.s., thomsen k.j., tribolo c., urbanova p., jain m., guibert p., mercier n., kreutzer s. & lahaye c. 2017. absorbed dose, equivalent dose, measured dose rates, and implications for osl age estimates: introducing the average dose model. quaternary geochronology 41, 163–173. landvik j.y., alexanderson h., henriksen m. & ingólfsson ó. 2014. landscape imprints of changing glacial regimes during ice sheet build-up and decay: a conceptual model from svalbard. quaternary science reviews 92, 258–268. landvik j.y., bolstad m., lycke a.k., mangerud j. & sejrup h.p. 1992. weichselian stratigraphy and palaeoenvironments at bellsund, western svalbard. boreas 21, 335–358. polar research 5 https://doi.org/10.1007/s41063-018-0037-z lycke a.k., mangerud j. & sejrup h.p. 1992. late quaternary foraminiferal stratigraphy from western svalbard. boreas 21, 271–288. mangerud j., bondevik s., gulliksen s., hufthammer a.k. & høisæter t. 2006. marine 14c reservoir ages for 19th century whales and molluscs from the north atlantic. quaternary science reviews 25, 3228–3245. mangerud j., dokken t., hebbeln d., heggen b., ingólfsson ó., landvik j.y., mejdahl v., svendsen j.i. & vorren t.o. 1998. fluctuations of the svalbard–barents sea ice sheet during the last 150 000 years. quaternary science reviews 17, 11–42. murray a.s. & funder s. 2003. optically stimulated luminescence dating of a danish eemian coastal marine deposit: a test of accuracy. quaternary science reviews 22, 1177–1183. murray a.s., marten r., johnson a. & martin p. 1987. analysis for naturally occurring radionuclides at environmental concentrations by gamma spectrometry. journal of radioanalytical and nuclear chemistry articles 115, 263– 288. murray a.s., wintle a. & wallinga j. 2002. dose estimation using quartz osl in the non-linear region of the growth curve. radiation protection dosimetry 101, 371–374. murray a.s. & wintle a.g. 2000. luminescence dating of quartz using an improved single-aliquot regenerativedose protocol. radiation measurements 32, 57–73. murray a.s. & wintle a.g. 2003. the single aliquot regenerative dose protocol: potential for improvements in reliability. radiation measurements 37, 377–381. prescott j.r. & hutton j.t. 1994. cosmic ray contributions to dose rates for luminescence and esr dating: large depths and long-term time variations. radiation measurements 23, 497–500. reimer p.j., bard e., bayliss a., beck j.w., blackwell p.g., bronk ramsey c., buck c.e., cheng h., edwards r.l., friedrich m., grootes p.m., guilderson t.p., haflidason h., hajdas i., hatté c., heaton t.j., hoffmann d.l., hogg a.g., hughen k.a., kaiser k.f., kromer b., manning s.w., niu m., reimer r.w., richards d.a., scott e.m., southon j.r., staff r.a., turney c.s.m. & van der plicht j. 2013. intcal13 and marine13 radiocarbon age calibration curves 0–50,000 years cal bp. radiocarbon 55, 1869–1887. tabachnick b.g. & fidell l.s. 1996. using multivariate statistics. new york: harpercollins college publishers thrasher i.m., mauz b., chiverrell r.c. & lang a. 2009. luminescence dating of glaciofluvial deposits: a review. earth-science reviews 97, 145–158. wallinga j. 2002. on the detection of osl age overestimation using single-aliquot techniques. geochronometria 21, 17–26. 6 h. alexanderson & j.y. landvik abstract introduction methods results discussion summary and conclusions acknowledgements disclosure statement funding references total mercury in hair of polar bears (ursus maritimus) from greenland and svalbard erik w . born, aristeo renzoni and rune dietz born. e . w . , rcnzoni. a . & dietz. r . 1991: total mercury in hair of polar bears ( u r s u s moririmlts) from greenland and svalbard. polar research 9(,7). 113-120. conccntratinns (ppm = pg/g dry wcight) of total mercury ( h g ) were determincd in hair of polar bean ((!r\ut marirbnus) from northwestern greenland ( n : 2 2 : pcriod of sampling: 197b1989). castern grccnland ( n = 44: 19841989) and svalbard ( n = 31: 1980). for subadults (2-h yearr of lifc). adults (7-10 yeara). and old bears ( > i 0 years). concentrations of total hg in hair were not found to he dcpcndent on agc or scx. a decreasing trend in hg conccntrations was found from west to east. the mean conccntrations of total hg in hair (cobs o f the year and yearlings cscludcd) were: northwcstern grccnland. x = 8.38 ppm (min.-max.: 1.71-14.19 ppm. n = 21): castern greenland: x = 1.28ppm ( m h m a x . : 2 . 5 c 8 . 8 3 ppni. n = 41): and svalbard. x = 1.98ppm (niin.-mas.: 1.02-4.ssppm. n = 2y). concentrationa found i n north wcatern greenland werc similar to those reported by others from the hair of polar bears samplcd within management zone f of thc eastern canadian nigh arctic. concentrations of total hg in polar hear hair from castern greenland were similar to concentrations found by other5 i n contemporary (1y88) material collected during spring in western svalbard. however. the mean concentration of total hg in the 1980 svalhard material, which was collected during july-september. was significantly lower than concentrations found in samples taken during late winter and spring in eastern greenland and at svalbard. respectively. presumably the relatively low concentrations found in the 1980 svalbard sample arc attributable to the period of moult and hence a larger proportion of newly grown hair in the individual samples. in a subsample consisting of internal tissues from 19 polar bears from eastern greenland (19841987). concentrations of total hg in hair correlated positively with concentrations of total hg (wet weight) in muscle ( n = 6). liver (n = 19) and kidney (n = 19) tissue. for liver and kidney tissue these relationships were statistically significant. erik w . born. greenland fisheries research institute. tagensuej 135, dk-2200 copenhagen n , denmark; aristeo renzoni, dipartimenro biologia amhientale, universita di siena. via delle cerrhia 3, 53100 siena. truly: rune dietz. greenland enuironmental research insriture. tagensoej 135, dk-2200 copenhagen n . denmark. introduction hair samples of mammals are considered to be good indicators of the body burden of mercury (johannesson et al. 1981; hansen 1981; renzoni 1989). concentrations in hair reflect blood mer cury or body burden of mercury during time of hair growth (sexton et al. 1978; kershaw et al. 1980). being a top predator which feeds almost exclusively on seals and in particular ringed seals (phoca hispida; e.g. stirling & archibald 1977; l0n0 1970), the polar bear can be considered a good indicator of the degree of bioaccumulation of persistent contaminants in its ecosystem. based on analyses of 128 recent (1977-1980) and 18 museum samples (1910-1927), eaton & farant (1982) presented concentrations of total mercury (hg) in polar bear hair from eight different localit ies in the canadian high arctic. liver samples from 67 polar bears from 1982 were analysed for mercury and 21 other elements by norstroni et al. (1986). renzoni & norstrom (1990) gave con centrations of total hg in hair sampled between 1976 and 1988 from a total of 141 polar bears in various localities in the canadian arctic, the ussr, and at svalbard (norway). concen trations of total and organic hg in muscle, liver and kidney in polar bears from central-eastern greenland were presented in dietz (1987), dietz et al. (1990) and dietz & agger (in press). here we present the results of analyses of total hg in hair from 66 polar bears from three localities in greenland with a note on the relationship between concentrations of total hg found in hair and in muscle, liver and kidney tissue. for com parative reasons analyses of total hg in 31 polar bear hair samples obtained at svalbard during july-september 1980 are included. 114 e . w. born, a. renzoni & r . dietz material and methods catch of polar bears. between january 1984 and august 1989 a total of 40 samples (year/sample a total of 66 hair samples (28 f, 37 m , 1 undet.) from greenland and 31 samples (15 f, 16 m ) from svalbard have been analysed for contents of total hg. the majority of the greenland samples were collected by hunters from their subsistence size: 1984/11; 1985/2; 1986/1, 1987/4; 1988/8: 1989/13; unknown/l) were obtained from the scoresby sound region of eastern greenland (fig. 1). four samples (2f, 2m) were obtained in 1989 from the ammassalik area in southeastern green frans josef land 0% % 9 4 svalb rd a b % sound 4 .$ arnrnassalik i fig. i . area5 in uhich polar bcar hair samples anal@ in thts atudy were obtained. t h c borders o f the canadian polar heal management zone f nrc l h m n with a dotted line (......). total mercury in hair of polar bears 115 land; a total of 22 samples (8 f, 14 m) were collected in the avanersuaq (thule) area in north western greenland. four of these samples were collected by scientists in may 1978; the remainder were collected by local hunters in 1988 (n = 7) and 1989 (n = 11). a total of 31 hair samples were collected by scientists during a swedish ice breaker expedition (ymer) operating in the sval bard area in 1980. the vast majority of the green land samples were from late winter and spring (january-may) while the svalbard-material was collected during “summer” (july-september; fig. 2). for 19 of the polar bears from the scoresby sound material (1984-1987), additional infor mation was available on total mercury content in muscle ( n = 6), liver (n = 19) and kidney ( n = 19) tissue. the hair samples were kept frozen in poly ethylene plastic bags until analysis (with the exception of the 1978 thule samples, which were stored dry in paper bags). the samples were carefully washed in acetone. rinsed and dried 14 12 10 8 6 4 2 0 no. l .mu o s c o n= 22 36 1 2 3 before being analysed for mercury residues at the laboratory of dipartimento biologia ambientale (siena) by atomic absorption spectrophotometry as described in renzoni et al. (1986). samples of internal tissues were kept frozen and stored in polyethylene plastic bags before being analysed at the laboratory of greenland environmental research institute by a method described in dietz et al. (1990). to detect whether concentrations of total hg in hair correlated with age, the polar bears were grouped into five age classes: cub of the year = coy, yearling, subadult. adult, and old. the age classes were based either on age obtained from reading of the annual layering in tooth cementum or on field age class estimates and body length. for a sub-sample from scoresby sound (n = 19; 1984-1987), individual ages were determined from the counting of the annual layering in the cementum of the lower premolars as described in stirling et al. (1977). for the 1978 thule-sample and the 1980 svalbard-sample, ages were esti amm b s v a l 4 5 6 7 4 31 8 9 10 11 12 month f i ~ . 2 . seasonal distribution of polar bear sampling from three different regions in greenland (thu = thule: sco = scoresby sound; amm = ammassalik) and svalbard (sva). four samples from scoresby sound presented in table 2 had no information on the date of sampling. 116 e . w . borri. a . retizoni & r . d i e n trrhlr i polar bear age cl.i\\c\ with zoological hod! lengths used in a n a l l z e s o f rclation5hip between t o t a l hg i n hair and age 1 i 4 i4 i a 15 i 111 mated i n the field by scientists. t h e majority of the greenland material was categorized into age classe\ according t o e 4 r n a t e s of age given b!. the h u n t e n i n the field together w i t h zoological body length measured from tip of snout to tip of tail along the back \ \ h e n the bear was positioned on its belly. l e n g t h data for these age classes are presented in table 1 where adult and old females are pooled hecause there was no difference in average body icngth of these age u . 5 ~ ~ . d i = i !is. p o . 0 5 ) . concentrations of total h g are given as ppm (1cg;g. d . ~ . ) in h a i r and 21s ppm (kcg'g. w . w . ) in other tiswes. the distrihutiun of hg in hair i n the differ ent areas did not differ significantly from nor mality (kolmogorov-smirnov one-sample tests: p > 0.05) but had significantly different variances (bartlett's test. x' = 19.567. p < 0.01). all data were in-transformed and a n o v a analyses were performed using the factors: area, sex, age. and the respective interactions o f these. statistics were made using statview 11 and superanova for a macintosh microcomputer. h g itr h i t concentrations of total h g found in polar hear hair in the four different areas are presented in table 2 . values for the two youngest age groups are given separately because young bears (i.e. cubs of the year = coys and yearlings) are assumed to be dependent o n milk until they are well into their second year of life (lqmo 1970). most cubs become independent when they are ii little over 24 months old (larsen 1986). in none of the samples were concentrations of total hg in hair related t o either age (age classes: suhadults, adults. olds) or to sex ( t w o factor a n o v a s ; p > 0.05). therefore. data from these two cat egories were pooled for further analyses. as con centrations of total h g in polar bear from ammassalik in southeastern greenland did not differ significantly from concentrations found in h a i r from the scoresby sound region ( f = 0.446. p < 0.05. df = 1/39). the samples froni these 7;7b!r 2 . c ' o n i c n t r d r i o n \ ( i q g d w . ) of t o t a l rncrcur! in hdir of polar bear\ troni greenland (l97&-19w) and svalhard ( i y k o ) . thc a v e r . i g c and crror r a n p c s arc calculated f r o m thc aiitihigarithni\ d t h e mean and the \tandard deviation of the in-transformed ~ ~~ data t h u l c i978-198y yearling 2 ?cars and older l y s 1 i y x y yearling?. 2 !car\ .ind vldcr ? !car\ and oldcr 1 "i iysii c u b 01 the !car yenrlin$ 2 \ e a r \ a n d d d s r y 51 8 38 i x i 1 h2 1.11 0 34 i in 1 4 s 6 . 3 b l l . 0 1 1.71-13 19 i h.lz (11 1.65-2.w 3.3%6. 17 3 i b s . s i 3 6%4.x' i . 4 1-6.02 1 21 3 27 4 i i 29 total mercury in hair of polar bears 117 j areas were pooled. the geometric mean con centrations of hg differed significantly between the three main areas ( f = 122.09, df = 2/88, p < 0.01). the northwestern greenland hg-con centration was 1.8 times and 4 . 3 times higher than mean concentration in eastern greenland and at svalbard, respectively (table 2). concentrations found in hair from eastern greenland were significantly higher than con centrations found in the sample taken at svalbard in 1980, but similar to concentrations reported by renzoni & norstrom (1990) for a sample obtained from svalbard during the spring of 1987 and 1988 (tukey's test; p < 0.01). in the east greenland sample the concen trations of total hg in hair collected during july and august (x = 5.23 ppm, rel. sd = 1.26, min. max.: 3.54-6.62ppm, 5m and 1f) did not differ significantly from concentrations in hair at other times of the year (f = 0.066; df = 3/33; p < 0.05). insufficient seasonal representation did not allow similar analyses to be performed for the other samples. le hg in hair h g in muscle, kidney and liver the relationships of concentrations of total hg in hair to concentrations of total hg in muscle. kidney and liver tissue from 19 polar bears sampled in the scoresby sound region (eastern greenland) between 1984 and 1987 in the period december-april are shown in fig. 3. con centrations of mercury in hair were found to be positively correlated with concentrations in tissue from kidney (r = 0.480, n = 19, p < 0.05), liver (r = 0.685, n = 19, p < 0.05), and muscle (r = 0.574, n = 6, n.s.). the slopes of the regression lines were significantly different from 0 at the same probability level for kidney and liver tissue, whereas no significance was detected for muscle tissue, probably due t o the low number of samples. 7 6 5 4 3. discussion concentrations of total hg in polar bear hair were highest i n northwestern greenland. however, the concentrations were in the same order of mag nitude as those reported by eaton & farant (1982) and renzoni & norstrom (1990) from the eastern canadian high arctic (i.e. within the canadian management zone f; fig. 1). recaptures in north hg in hair el . 0 0 0 * % 0 . . . i 0 0 a r = ,685 8 7 lz hg in hair 0 6 5 4 b 0 0 0 r = ,574 3 1 2l i hg in liver llg in muscle 0 0 .02 .04 .oh .08 . i . i 2 . i 4 i . *. . . . . . 0 . 0 i hg in k i d n e y ii 6 ' b 10 20 30 40 so 613 118 e . w . born, a . renzoni & r . dierz western greenland of polar bears which were marked i n zone f (rosing-asvid & born 1990) indicate that polar hears move freely between these areas. concentrations of total h g in hair from polar bears from eastern greenland were similar to values reported by renzoni & norstrom (1990) for a sample taken during spring in western sval bard. satellite tracking (larsen e t al. 1983) and movements of marked bears (larsen 1986) indi cate that exchange occurs between polar bears in eastern greenland and in the svalbard frans josef land region. however, t o what extent local groups of bears exist within this range still remains undetermined (born & rosing-asvid 1989). eaton & farant (1982) and renzoni & nor strom ( 1990) suggested that geographical vari ation in concentrations of total hg in the hair of polar bears in the canadian high arctic t o some extent reflects different ratios of the bottom-feed ing bearded seals (erignurhus burbutus) to the more pelagic ringed seals in the diet of the bears in the various areas. t h e very limited and highly heterogeneous information available on the feed ing of polar bears i n greenland (pedersen 1945: born upubl. d a t a ) and at svalbard ( l o n 0 1970) does not allow for an evaluation of geographical variation in polar hear diet in these areas. o n the other hand. dietz & agger (in press) state that the only differences found in mercury levels in bearded seals and ringed seals from nw green land are found in liver tissue. as also found in smith & armstrong (1975) i n canada. whereas no differences were found between these two species in blubber and muscle and kidney tissue. we suggest that the differences found in our study in concentrations of total h g in hair from greenland polar bears mainly reflect variations in the overall mercury burden of the environment rather than different proportions of various prey species in their diet. norstrom et al. (1986) found that mercury con centrations in polar bears from the western part of the canadian arctic tended t o be higher than in the eastern part. likewise mercury con centrations in the northern areas at melville island were higher than in southern regions. dietz & agger (in press). who found that con centrations of total h g in the liver tissue of polar bears from eastern greenland were lower than those reported by norstrom et al. (1986), confirm a decreasing trend in h g concentrations from west to east. higher concentrations of h g were found in polar bear hair sampled at southwestern svalbard in 1987 and 1988 (renzoni & norstrom 1990) than in a sample from the pack ice areas around the archipelago in 1980. to our knowledge there is n o information which indicates that the total mercury burden of the marine environment of the svalbard region has increased within the last decade and we suspect that the relatively low concentrations of total h g found in the 1980 sample from svalbard reflect seasonal variation related to moulting of hair. t h e 1980 svalbard samples (this study) were collected from “summer fur“ while the samples analysed by renzoni & norstrom (1990) were taken during march-april from “winter fur.” t h e majority of samples from greenland were collected between january and may from “winter fur” (fig. 2) which presumably is also the case with samples in other studies (eaton & farant 1982; renzoni & norstrom 1990). although information on t h e timing of the process of moulting in polar bears is somewhat contradictory (freuchen 1935; pedersen 1945; uspenski 1979 citing rutilevski 1939; vibe 1981), i t appears that generally the moult begins in late may and that the new winter coat has grown in autumn (september-october?). o u r assumption that hairs of “summer fur” have lower concentrations of total h g than hairs of winter fur was. however, not supported by the finding that in only six samples, taken in july and august in eastern greenland, the mean con centration was not significantly different from the mean concentration in hairs sampled in t h e same area during other seasons. we suggest that t h e low h g levels found in “summer” hair are caused by accelerated hair growth during the moult. however, it remains undetermined whether the different concentra tions found at svalbard (this study and renzoni & norstrom 1990) also reflect sampling of different segments of the polar bear population at different times of the year and/or seasonal variations in the food of polar bears. in samples from 55 polar bears taken between january and may in 1982 i n seven areas within the central canadian high arctic. renzoni & norstrom (1990) did not tind a statistically signifi cant correlation between total hg in hair and live tissue. in contrast. in a smaller sample taken during spring in eastern greenland we found that concentrations of total h g in hair correlated posi tively with concentrations of total h g in internal total mercury in hair of polar bears 119 bulletin of environmental contamination & toxicology 35. 49g495. born, e. w. & rosing-asvid, a . 1989: i s b j ~ r n e n (ursus mar itimus) i g r ~ n l a n d : en oversigt (the polar bear in greenland: a review). teknisk rapport grgnlands hjemmestyre, milj@ og naturforualtning. 3900 nuuk. rapport nr. 8 oktober 1989. 126 pp. (in danish with english summary). dietz, r . 1987: tungmetaller i isbj~irn og andre arktiske dyr/ nannuni issittullu uumasuini allani saffiugassat oqimaatsut (heavy metals in polar bears and other arctic animals). forskning i gr@nland ltusaat 1987 ( 2 ) . 2-13 (in danish and greenlandic). dietz. r.. nielsen. c. 0.. hansen. m. m . . & hansen, c . t . 1990: organic mercury in greenland birds and mammals. the science of the total environment 95 (1990), 41-51. dietz. r . & agger. c. t . (in press): recent studies on heavy metals in polar bears from greenland with reference to other marine mammals. abstract "contaminants in the arctic." 18th annual aquatic toxicity workshop, 30 september-3 october 1991, ottawa, canada. eaton. r. d. p. & farant j . p. 1982: the polar bear as a biological indicator of the environmental mercury burden. arcfic 35 ( 3 ) , 422-425. freeman. h . c. & horne. d . a . 1973: mercury in canadian seals. bullrtin of enuironmental contamination & toxicology 10. 172-180. freuchen. p . 1935: polar bears (ursus maritimw). pp. 102-1 19 in mammals, part 11. field notes and biological observations. rep. fifth thule expedition 1921-24. 21455), 68-278. hansen, j. 1981: a survey of human exposure to mercury, cadmium and lead in greenland. meddr. gr@nland man. & society 3 . 36 pp. itano, k . , kawai, s . , miyazaki. n.. tatsukawa, r. & fujiyama. t . 1984: mercury and selenium levels in striped dolphins caught off the pacific coast of japan. agric. biol. chen. 48(5), 1 10%1116. johannesson. t.. lundc. g. 61 steinnes. e . 1981: mercury. arsenic. cadmium. selcnium and zinc i n human hair and salmon fries in iceland. acra pharmacol. er towicol. 48. 1x5 18y. kershaw. t. g . . dhahir, p. j . & clarkson. t . w . 19x0: the relationship between blood levels and dose of methyl mercury in man. arch. enoiron. healrh 3.5. 28-35. larsen, t. 1986: population biology of the polar bear (ursus maritimus) in the svalbard area. norsk polarimtitutts skrifter 184. 5 5 pp. larsen. t . . jonkel. c. & vibe, c. 1983: satellite radio-tracking of polar bears between svalbard and greenland. lnt. conf. bear res. manage. 5, 23s237. l0n0, 0. 1970: the polar bear ( u r s w maritimus phipps) in the svalbard area. norsk polarirrrtitutts skrijter 149. 103 pp. norstrom, r . i . , schweinsburg. r . e. & collins, b. t. 19x6: heavy metals and essential elements in livers of the polar bear (ursus maritimus) in the canadian arctic. the science of the total environment 48, 191-212. pedersen, a . 1945: der eisbar (thalarctos maritimus phipps) verbreitung und lebensweise. bruun & co.. k ~ b e n h a v n . 16 pp. (in german). renzoni, a . 1989: mercury in scalp hair of maldivians. marine pollution bulletin 20(2). 9>94. renzoni, a . & norstrom, r . 1990: mercury in thc hairs of polar bears ursirs maritimus. polar record 26(159). 326-328. renzoni. a , . focardi, s.. fossi, c.. lconzio, c. & mayol. j . 1986: comparison between concentrations of mercury and tissues with a capacity for long term accumulation of mercury. a n explanation for this apparent discrepancy found in the two studies could be that samples from various areas in canada were pooled in the renzoni & norstrom (1990) study whereas the east greenland material is more homogenenous since it was sampled in only one area. the mercury concentrations in the hair as well as in the internal organs reflect the contamination levels in the food of the polar bears. therefore, it appears less surprising that we found a correlation between h g in hair and in internal tissues. this is in agreement with previous findings by for example freeman & horne (1973). who stated that claws and fur from the gray seal (halichoerus gr.ypus) and the harp seal (pagophilus groen landicus) were good indicators of the degree of mercury contamination in muscle, liver, kidney and heart tissue. similarly, bacher (1985) found a significant correlation between mercury in hair and in internal tissues (muscle, liver, spleen, brain) of australian fur seals (arctocephalus p u sillus). furthermore, if o n e regards hair as o n e of the excretion routes of h g (see itano e t al. 1984). it seems reasonable to assume that h g con centrations in hair in a general way reflect the h g level in the internal tissues of an individual. we conclude that concentrations of total mer cury in polar bear hair from late winter and spring reflect the overall mercury burden in the eco system within the range of the various polar bear populations. w e suggest that the relatively low concentrations of total mercury found in samples obtained during summer can be related to the process of moulting. based on a small sample from eastern greenland we have found indi cations that concentrations of total h g in hair taken during spring reflect levels of total mercury in liver and kidney tissue. a c k n o d e d g e m e n t ~ . wc wish to thank the grccnland inuit and our colleagues who provided the samples. thanks arc also duc to the canadian wildlife scrvicc (edmonton) for making age determinations of somc of the tceth, and to our laboratory technicians who made the metal analyses. we are grateful for the constructive criticism offered to the draft by j . hanscn (institute of hygienc, university of aarhus). r. norstrom (canadian wildlife service), and 0 . wiig (norwegian polar research institute) and two anonymous referees. references bachcr, g . j. 198.5: mercury concentrations in the australian fur seal (arctocephalus pusillus) from se australian waters. 120 e . w . born, a . rerizoni & r . dietz other contaminants i n eggs and tissues of cory's shearwater. culoriecfrrs diomedeu collected on atlantic and med iterranean islands eni~iron~neitfal poilurion. ser. a 40. 17 3 5 . kosing-asvid. a . & born. e. w . 1990: fangst af ishj0rn (ursus maritimur) i avanersuaq og upernavik kommuner: en inler viewunders~gelse (polar bear hunting in the avanersuaq and upernavik areas: a n interview survey). teknrsk rupporf grdnlands hjerntnrsn re afddingen for l e i ~ e i i d e restoiircer. 3900 .vuuk. .vr. 23 deceinber iyyo. 63 pp. (in danish with english \urnmar).). rutiic\,hi. c j . l 1y.w prtm)\lo rnlekopitajuscic poluo \tro\;i celluskin'i i z i i l i \ i i vi ickogo. triid! naiicii. rsa/ed. pol/arri x . 7-mi ( i n k u s h n . not conwilted dtrcctly 1 . sexton. d. j , powell. k . t.. liddle. j r. sinrek. a . 197x: a nonoccupational outhrcak of inorganic mercury poisoning. arch. enuiron. heulrh 3 , 186191. smith. t. g . & armstrong. f. a . j . 1975: mercury in scals. terrestrial carnivores. and principal food items of the inuit from holman. nwt. j. fish. res. b d . can. 32 ( 6 ) , 795-801. stirling. i . r. archibald. k. 1977: aspects of predation of seals by polar bears. j. fish. re.\. b d . cun. 34(x), 112&1120. stirling. i . . archibald. w. r . & schwcinsburg, r . e . 1y77: distribution and abundance o f scals in the eastern bcaufnrt sea. j. fi.\/i. res. bd. curl. 2 4 . y1wx-x. lispentki. s . m . 1979, der eisbur. die nrur rrehm-hucherei. a zicrnscn verlag. witlcnberg luthcrstadi. 112 pp. ( i n ger m a n ) . vihc c. 19x1: ishjmn (ursus rnarifimus), nanok (polar bear). pp. 383-387 in salomonscn, f. (ed.): (ironlands fauna. fkk, fugle. paffedyr. gyldcndal. kqbenhavn. 464 pp. (in danish). distribution of puffins fratercula arctica feeding o f f rest, northern norway, during the breeding season, in relation to chick growth, prey and oceanographical parameters tycho anker-nilssen and svein-hakon lorentsen anker-nilsscn, t. & lorentsen, s.-h. 1990: distribution of puffins fratercula arctica feeding off rest, northern norway, during the breeding season, in relation to chick growth, prey and oceanographical parameters. polar research 8 , 67-76. in 1988, first-year herring clupea harengus were the dominant prey fed to puffin chicks on hernyken, r0st. puffins carrying food loads were observed at least 137 km from thc colonies in july. in early august, two major fccding areas were located about 20 and 85-105 km off r0st. these long foraging ranges and a n insufficient availability of food are thought to be the main reasons for the poor chick growth this year. no relationships were found between the distribution of puffins observed at sea and survey station data on prey distribution, sea temperature or salinity, but this may have been due to inadequate sampling of these parameters. a recorded seasonal change in flight direction of adults returning to colony is discussed in relation to food quality and chick growth. tycho anker-nilssen and svein-hikon lorentsen, norwegian institute for nature research, tungasietta 2 , n-7004 trondheim, norway; september 1989 (revised january 1990). there have been few studies of the distribution of puffins fratercula arctica feeding around their colonies during the breeding season. breeding puffins feed their chicks mainly pelagic schooling fish, the most important being herring clupea harengus, capelin mallotus villosus, sandeel ammodytes s p p . and sprat sprattus sprattus (harris 1984). schneider et al. (in press) found puffins collecting chick food normally within 10 km of a colony in newfoundland, but occasion ally they flew up t o 70 km offshore, which has been the maximum foraging range recorded for this species. furness & barrett (1985) suggested a short foraging range around hornciy, ne norway. estimations based on flight speed and periods of time spent away on fishing trips have sometimes indicated maximum ranges of more than 100 km for some populations (pearson 1968; bradstreet & brown 1985). however, in most areas puffins forage relatively close to the colony (harris 1984; bradstreet & brown 1985). studies of fish net catches and dive times suggest that they normally do not dive below 3 0 m , and the maximum recorded diving depth of puffins is less than 70m (bradstreet & brown 1985; piatt & nettleship 1985; burger & simpson 1986). since 1969, puffins breeding on rost have experienced a shortage of food for chicks, and in most years virtually all young have died from starvation (lid 1981 ; anker-nilssen 1987). their breeding success at this site is strongly dependent on the occurrence of first-year herring from the atlanto-scandian stock (anker-nilssen 1987; barrett et al. 1987). the spawning stock of at lanto-scandian herring collapsed following over fishing in the late 1960s (jakobsson 1985; rott ingen 1985), and has only recovered slightly in more recent years (hamre 1988; anon. 1989). puffin numbers on r0st decreased dramatically following these breeding failures, and the popu lation in 1988 was only 36% of that breeding in 1979 (anker-nilssen & rcistad unpublished). the availability of food, and especially of 0-group herring during the breeding season, is thus prob ably the most important factor currently regu lating the size of this population. it is therefore likely that the distribution of puffins at sea off rcist in summer is primarily determined by the distribution of their most important prey. prior to 1988, the puffins on rost had only been studied at the colonies. in order to learn more about the feeding ecology of rcist puffins, 68 t. anker-nilssen & s.-h. lorentsen we investigated the relationships between puffin distribution at sea and the distribution and abun dance of their prey. we also examined foraging range, food quality and chick growth. methods and material studies in colony we studied puffins during the 1988 breeding sea son on hernyken (67”26’n, 11”52’e, fig. l ) . with c. 43,000 occupied nest burrows in 1988, this island is one of the five major puffin colonies in the r0st archipelago (anker-nilssen & rostad unpublished). the traffic of puffins returning from feeding trips was studied on 24 occasions between 16 july and 16 august from a fixed observation site located 82 m above sea level, normally between 1300-1800 hours (1200-1700 gmt). with the exception of an obscured sector towards the ne of this point, the sea horizon was divided into 26 sectors, one for each 11.25’. in each sector the number of arriving groups of puffins was counted for 2 minutes, using a telescope ( 2 0 ~ ) aligned on the midpoint of the sector with the horizon in centre of the view. since birds tended to spread out when approaching the colony, only groups flying directly towards the observer and at dis tances beyond 3 4 km (well outside the outermost skerries) were counted. food loads intended for chicks were collected from adults caught in mist-nets placed in the colony. in each load, fish species were identified and weighed separately to the nearest 0.1 g, and their body lengths were measured to the nearest 1 mm. occasionally, numerous small post-larvae of a single species were weighed collectively. in such cases, only the maximum and minimum length within the group were recorded. alto gether, 105 food loads (of which 93 were complete) containing a total of 1,072 individual prey items were collected during 21 days between 13 july and 19 august. all the adult birds caught during the sampling of food loads were weighed to the nearest 5 g . chick growth and fledging success were studied in 101 accessible nests containing an egg in mid june. all chicks found in these nests (n = 52) were weighed at 2-3 day intervals from 14 july to 24 august and on 1 september. studies at sea the institute of marine research (imr) in bergen conducted two ship surveys in july 1988 in order to map the distribution and abundance of first-year herring off the central and northern coasts of norway. the two research vessels, ‘hikon mosby’ and ‘sula’, covered the sea areas off rgst from 16-20 july, and a seabird observer was present aboard ‘hikon mosby’. both ships sampled sea temperature and salinity at a depth of 20 m on fixed transect stations (fig. l), where they trawled for post-larvae and 0 group fish in the 0-60 m depth zone, cruising at a speed of 2-3 knots for 30min. the distance between successive imr stations within the tran sects varied between 24 and 56 km (13-30 nautical miles). imr scientists identified and counted all fish in each trawl catch, and measured the body lengths of individuals in a random sample of each species. on 3 4 august, the whaler ‘dag senior’ was chartered in order to locate major foraging areas of the r0st puffins. the survey was directed towards the main incoming direction of birds registered on hernyken on 2 august, but the ship’s course was adjusted at sea to trace thc incoming stream of puffins (fig. 1). a very short transect was run a few km nw of rost on 5 august with the smaller vessel ‘falken’, but the results are treated here as being part of the ‘dag senior’ cruise. hydrography and fish were not sampled during the august surveys. seabirds at sea were counted in 10-minute periods, using standard procedures (tasker et al. 1984). transect width was normally 300 m t o one side of the ship. the observation standpoints aboard ‘hikon mosby’ and ‘dag senior’ were 10 m and 6 m above sea level, respectively. ship speed for the counts was from 8-12 knots, and was held constant on straight transects. birds flying were counted separately from birds on sur face, and the flight direction of puffins was recorded. whenever possible on the ‘dag senior’ cruise it was noted whether or not the puffins were carrying food. seabirds were counted for 485 km of the transects run by ‘hgkon mosby’ between 6669”n and for 322km of the ‘dag senior’ cruise. statistical analyses and graph plots were made by using the spss (statistical package for social sciences) and css (complete statistical system) computer packages. distribution of pufjins during the breeding season 69 results flight direction of puflns returning to colony the median direction towards groups of adults returning from the fishing grounds varied sig nificantly throughout the season (kruskal-wallis h = 183.9, df = 16, p < 0.001). it was fairly con stant about wsw during the second half of july, whereafter it turned gradually towards nw until mid august (fig. 2 ) . at the end of the season, there was a dramatic shift in direction, as most birds were returning from sw. foraging areas during the ‘hikon mosby’ transects, the highest density of puffins on surface was recorded 137 km nw of rdst, off the edge of the continental shelf (figs. 3 and 4). this was primarily due to a single dense flock of about 300 birds foraging actively within the transect. several flying birds were observed carrying food loads in this area, but poor light conditions made quantitative observations difficult. within 110 km of rest, the majority of fig. 1. stations sampled by the research vessels ‘hhkon mosby’ (filled circles) and ‘sula’ (open circles) 16.20 july 1988. seabird counts in transects were made from ‘hikon mosby’ (thick lines). similar counts were done during the cruise with ‘dag senior’ on 3 4 august 1988 (thin lines). the location of hernyken is indicated by the arrow. station numbers refer to table 2. the birds were flying, while birds on surface were predominant further out. in the southernmost transect, puffins were observed settled on surface as far as 208 km sw of rdst or 240 km from the next nearest puffin colony, lovunden (66”23’n, 12”20’e) (fig. 3). however, we were unable to establish the origin and breeding status of these birds. puffin densities, particularly in flight, were gen erally higher on 3-4 august than those recorded two weeks earlier (figs. 5 and 6). this was expected as the august survey aimed t o find the major feeding areas, and transect routes therefore were chosen according to the traffic of puffins to and from the colonies. two major foraging areas were found in early august, one c. 20km w of the colonies and another 85-105 km to the nw. between these two areas, as well as closer to rdst, there was a steady traffic of birds flying to and from the col onies (fig. 6). the outer area was located over the continental slope, at its closest point of approach t o r0st (fig. 5). here we observed the characteristic dense schools of 0-group herring 70 t. anker-nilssen & s . h . lorentsen nw. w. sw. date fig. 2. median direction (k1 quartile) from which groups of adult puffin3 returned to hernyken in 1988. in the surface layer close t o foraging puffins. however, some puffins were seen carrying food loads from beyond this distant feeding area. chick food, growth and fledging success the composition of food brought to puffin chicks on hernyken varied throughout the season (fig. 7), as did load weights and the number of prey items per load (fig. 8). generally, herring was the most important food, although saithe pol luchius uirens, haddock melanograminus aegle finus and rockling rhinonemus spp. were important for shorter periods. the amount of herring in the diet increased gradually in july, and was the only prey recorded between 30 july and 3 august, whereafter its importance decreased and accounted for c. 50% of the food weight in mid august. load weights varied significantly between 5 day periods (kruskal-wallis h = 20.62, df = 8, p < 0.01, fig. 8), as did the number of preys per load (kruskal-wallish = 23.94, df = 8, p < 0.01, fig. 8). during july, median load weights were fairly stable between 8-10 g, but decreased rather suddenly in early august and remained low (5 6 g) during the rest of the sampling period. most of the variation in median numbers per load was closely related to the corresponding shifts in weight dominance of preys (fig. 7 ) , being low (3 5) with saithe and haddock, medium (9-11) with herring and high (20-24) when small rockling was predominating. except for two short periods, the average chick fig. 3. density of puffins (birds/km2) on the sea surface 16-20 july 1988. data are aggregated to 10 x 10 km squares. a completely filled circle represents 50 birds/km*. depth contours are in metres. distribution of puffins during the breeding season 71 distance nw from colony km fig. 4. mean density of puffins (birds/kmz) flying (dotted line) o r o n thc sea surface (thick line) in relation to distance from colony, as obscrved in 10-minute intervals during the ‘hbkon moshy’ franscct directed nw from rest 18 july 1988. the total numbcr of puffins ohserved within the transect area was 2,414. weight increased by 2-6g per day until early august, then growth retarded and chicks lost weight rapidly (fig. 9). when the data were aggre gated into 5-day periods, there was a significant relationship between the average weight change of chicks and the proportion of herring in their diet between 15 july and 18 august (spearman rank correlation, r = 0.7857, df = 5 , p < 0.05). the latest check (1 september) showed that only 2 study nests still contained a chick. at least 38 of 50 study chicks died in the nest and the maximum fledging success was estimated to 24%. furthermore, those chicks that left the nest did so in a very poor condition, as the last recorded weight of the 12 study chicks that could have fledged averaged 197.3 g (sd = 29.5). the mean weight of 39 other fledglings checked on their way to the sea from 14-21 august was equally low (197.9g, sd = 25.8). in late august and early september, several hundred dead chicks were seen floating on the sea near the colonies. five of these chicks were dried, and their mean weight was only 133.4 g (sd = 6.1). adult body weight between 14 july and 20 august, 17 adult puffins were weighed more than once. nine of them were carrying food, while 5 of the others had been ringed as ‘adults’ (with a 2 bill grooves) at exactly the same location between 1980 and 1983 (one fig. 5. density of puffins (birds/kmz) on the sea surface 3-4 august 1988. data are aggregated to 10 x 10 km squares. a completely filled circle represents 50 birds/km*. depth contours are in metres. .. ..’ .. ............. \ .. ................. .. ............ .. .. .. ,. to i 001 08 09 ot 02 0 edu+“~w *.” aq& ........... 12 t . anker-nilssen & s . h . lorentsen fig. 6. mean density of puffins (birds/km2) flying (dotted line) or on the sea surface (thick line) in relation to distance from colony, as observed in lo-minute intervals during the ‘dag senior’ cruise nw of rest 3-4 august 1988. the total number of puffins observed within the transect area was 6,463. fig. 8. seasonal change in the median weight (lower) and median number of prey items (upper) in complete food loads brought to puffin chicks on hernyken during 5-day periods in 1988. dotted lines show medians f 1 quartilc. n = no. of complcte loads examined in each period. fig. 7. seasonal change in the composition of the principal prey species (percentage of diet by weight) brought to puffin chicks on hernyken during 5-day periods in 1988. the number of food loads examined in each period is indicated. with food load in 1982). these 14 birds, which the number of fish (1-12,000) and their median were considered to be breeders, lost weight at a lengths (30.0-45.0 mm). this variation was also mean rate of 0.70 g/day (sd = 2.7, n = 17) evident between the transect stations nw of r@st between successive retraps, but the decline was on 18 july (kruskal-wallis tests, p < 0.001), but not statistically significant (anova on could not be explained in relation to sampling regression, f = 0.70, df = 1.15, p > 0.25). hour or distance from the colonies (table 2). in order to test if the distribution of puffins comparisons with fisheries research data herring selected by puffins were considerably larger than those sampled by imr (kolmogorov smirnov d = 0.384, p < 0.001, table 1). this was also the case for haddock (k-s d = 0.749, p<o.ol) but not for saithe (k-s d =0.212, p > 0.05). at this time, haddock and saithe in puffin loads were of the same size (k-s d = 0.25, the catch of herring in trawl samples varied greatly between stations, with respect both to p = 1). observed on surface during the ‘hiikon mosby’ transects could be explained by the variation in herring or oceanographical parameters sampled by imr, the puffin data were allocated to the nearest imr sampling station (cf. fig. 1). herring biomass was estimated from the length measure ments sampled by imr, using a weight-length relationship derived from herring brought to puf fin chicks on hernyken from 13-23 july (fig. 10). no significant relationships were found between the surface density of puffins and her ring biomass, herring numbers, sea temperature distribution of puffins during the breeding season 73 2. 1' 0.8. a6 . a4 6 a 7 , , ' , ,. , ' d 17.7 22.7 27.7 1.8 6.8 11.8 16.8 21.8 268 318 date fig. 9. mean daily weight change ( k l se) of individual study chicks on r0st in 1988. n values are shown in top line. or salinity at adjacent imr stations from 16-20 july (table 3). the correlations did not improve when only herring of sizes taken by puffins (>32mm) were selected, nor when the puffin data were weighted according to the linear dis tance from reist, or when only puffin densities within 5 km (2.7 nautical miles) of each station were used. the paucity of puffin data did not permit much further reduction of the comparative scale, while comparisons on scales larger than the mean distance between successive stations (table 3) were not made due to the low number of stations. discussion first-year herring was undoubtedly the most important prey fed to puffin chicks on reist in 1988. judged on the flight direction of adults returning t o colony when chick provisioning was significant, the main feeding grounds were located / rr i + n 77 0 herring length mm (log scale) fig. 10. correlation between log length and log weight of herring brought to puffin chicks on hernyken 13-23 july 1988 (r = 0.9489, p < 0.001). n = sample size. west of rast, shifting gradually from wsw to nw through most of the nestling period. late in the season, there was a sudden shift in the return direction. this event coincided with an evident decrease in food provisioning of chicks, causing most of the already starving nestlings to lose weight and die. in two years with good breeding success, 1983 and 1985, the average fledging weights of puffin chicks on reist were 301.5 g and 267.5 g, respectively (anker-nilssen 1987). thus, the fledging weights of the few chicks that did survive the nestling period in 1988 confirm that they were severely undernourished. the results show that significant numbers of puffins were collecting food for their chick from a considerable distance. on 18 july, some were seen at least 137 km from the colony, which is tuble 1. summary statistics for the length distribution (mm) of three major puffin preys in 1988 sampled by adult puffins breeding on hernyken (13-23 july) and by imr's research vessels off rest (16-20 july). nw indicates data for the 6 innermost stations in the transect nw from r0st (18 july, cf. fig. 1 ) . species sample median mode range mean sd n herring puffins 41.0 3s 33-94 45.02 11.08 264 imr 35.0 32 20-59 35.71 5.59 865 imr nw 32.0 32 22-54 33.68 5.47 197 haddock puffins 102.5 100 85-120 104.67 13.28 6 imr 45.0 42 1?-115 48.15 21.30 548 saithe puffins 97.0 100 75-126 95.58 12.01 24 imr 93.0 88 32-117 93.03 14.42 39 74 t . anker-nilssen & s.-h. lorentsen table2. the median length, total number (n) and total biomass of herring caught per half hour trawl periods in relation to time of day and distance from the colonies at the 6 innermost imr transect stations nw of rest 18 july 1988 (cf. fig. 1). n = no. of herring measured. distance median total station from colony length biomass no. hour km mm n n g 67 0800 17 36.5 10 11 2-74 68 1000 40 32.0 35 35 5.26 69 1200 68 32.0 53 165 17.27 70 1500 93 31.0 24 27 3.16 71 1700 117 32.5 26 27 5.25 72 2100 172 34.0 49 54 9.97 twice the maximum foraging range reported from other areas (70 km, schneider et al. in press). using the flight speed of 48 km/h recorded by corkhill (1973), these birds spent a minimum of 5.7 hours flying in order to return with a load of 8-9 g. observations made by local fishermen indicate that the foraging range of r0st puffins has also been considerable in previous years (anker-nilssen 1987). unfortunately, feeding frequency was not stud ied on r ~ s t in 1988, but chick growth was very poor from 17-20 july with only slightly increasing chick weights. compared to puffin chicks at bleiksoy in 1982, which slowly gained weight with a food consumption of 23-32 g/day (barrett et al. 1987), it is reasonable to believe that the chicks on hernyken received no more than this in 1988. nevertheless, each adult had to make 1-2 feeding trips per day, spending may be up t o 50% of their time away from colony. in early august, the maximum recorded foraging range dropped by 25% compared t o that of mid july, but then the median load weight was c. 40% lower. these findings show that the maximum foraging ranges of more than 100 km estimated by pearson (1968) and bradstreet & brown (1985) are within the capability of breeding puffins. furthermore, we have no indications that these long foraging ranges caused energy stress of adults on rgst in 1988. the recorded weight changes of individual birds represent an average loss of c. 4% of their prelaying body weight over one month, but this may be adaptive and is within the range of what has been recorded on rest in previous breeding seasons ( 4 6 % per month, barrett et al. 1985). at the peak of their growth, puffin chicks require at least 50 g food per day to stay in good condition (myrberget 1962; harris 1976; tschanz 1979; barrett et al. 1987). if prey was easily caught in the distant foraging areas in 1988, the puffins could, theoretically, have had just enough time in a day to provide their chicks with sufficient food. consequently, the poor chick growth strongly suggests that prey was limited and/or that the adults did not devote all their time to feed the young. when compared to food loads collected on rost in previous seasons (anker nilssen 1987), load weights were very poor in august 1988, and indicated that prey was limited. no significant relationships were found between puffins at sea and the recorded distri bution of herring in july. nevertheless, we believe that the steady shift in return direction to the colonies during the nestling season reflects the drift of herring northwards to the nursery areas of immature atlanto-scandian herring in the barents sea (e.g. hamre 1988). the speeds of the collateral coastal and atlantic ocean currents west of r ~ s t may periodically be relatively fast (up to 2 knots, sotre et al. 1979). however, the bottom topography causes frequent formation of eddies in the frontal system between the two table 3 . coefficients and p values (in parentheses) for spearman rank correlations between the density of puffins on surface and herring biomass, herring numbers, sea temperature and sea salinity 16-20 july 1988. only data from imr stations where adjaccnt puffin data were available were used (cf. ‘hbkon mosby’ survey, fig. l ) , either from all of these stations (n = 11), or only from those in the transect nw from r0st (n = 6). the spatial scale for the comparisons corresponds to the average distance between successive stations. data set spatial scale herring herring sea sea (km) biomass numbers temperature salinity all stations 38.4 -0.1549 -0.2283 -0.2975 (0.649) (0.500) (0.374) (0.787) (0.957) (0.156) nw transect 32.2 0.1429 0.0290 0.657 1 -0.0685 (0.841) (0.397) -0.4286 distribution of pufjins during the breeding season 7 5 water masses, which may lead to an increase in the retention time and density of young herring in the area (sundby 1984 pers. comm.). the major aggregations of feeding puffins were located over the continental slope in areas where a frontal system is especially pronounced (szetre et al. 1979). well developed frontal systems bene fit primary production which in turn creates favourable conditions for schooling fish like the young herring (e.g. tait 1981). this, plus the retention of prey in occasional eddies off rest, may well be a key factor explaining why rost is the largest puffin colony in norway. the rapid shift in return direction of puffins observed late in the season, accompanied by a sudden retardation in chick growth, suggests that most herring nw of r0st at this time had become unavailable for the puffins. possible causes are that the herring had drifted too far away from rost, that they were depleted by other predators (e.g. adult herring, v. 0iestad pers. comm.), or that they went too deep for the puffins to reach them. our data suggest that distance from the colony was critical in 1988. although the imr vessels and the puffins apparently sampled fish from the same areas, the birds took significantly larger herrings than those sampled by the imr. this indicates that the puf fins actively selected the largest fish in the schools, and/or that most of these herring were able to avoid the trawl. however, the major bias in our study is undoubtedly the discontinuous sampling of fish and hydrographical parameters, and the fact that birds were not counted at imr hydrography or trawl stations. furthermore, through the 20 m sampling depth for sea temperature and salinity, local fronts in the surface layer may have been missed. the expected patchiness in the distri bution of both herring and puffins was evident, and has likely severely reduced the probability of finding any significant relationships. scale-dependent patchiness is crucial and demands special attention (see hunt & schneider 1987 for a review), and only a few studies have succeeded in finding positive correlations between the distribution of seabirds and their prey. sch neider & piatt (1986), heinemann et al. (1989) and erikstad et al. (1990) all found that the degree of correlation was higher at larger spatial scales, although erikstad et al. (1990) suggested that the coefficients in their study reached an upper largest scale used in our study was only 38 km (21 nautical miles), but the low number of sampling stations would have made comparisons on larger scales unreliable. this study documents the close relationship between the breeding success of r0st puffins and the amount of herring they fed their chicks in 1988. although we were unable to find any relationships between the simultaneous occur rences of puffins and first-year herring, we cannot reject the theory that prey availability is the key factor determining the distribution of puffins at sea off r$st during the breeding season. however, in order to fully understand the import ance of this predator-prey relationship, it will be necessary to increase sampling and modify sampling procedures in future studies. acknowledgements. we are indebted to 1. alm, p. anker nilssen, b. h. larsen and .i. 0 s t n e s who assisted in the field, and to h. bjdrke and s . sundby at the institute of marine research in bergen for providing us with and allowing us to use unpublished data from imr’s juvenile fish surveys. thanks are also due to m. taskcr for his constructive refereeing of this paper, and to k. e. erikstad and r. t . barrett for valuablc comments. r . t. barrett also kindly improved the english, the studies at sea were part of a seabird project within the environmental impact assessment programme for the ccntral norwegian continental shelf, and were financed by the royal norwegian ministry of petroleum and energy. the land-based part of the study reccived funds from the norwegian directorate for nature management. references anker-nilssen, t. 1987: the breeding performance of puffins fratercula arctica on r m t , northern norway in 1979-1985. fauna noru. ser. c, cinclus 10, 21-38. anon. 1989: ressursoversikt for 1989 og havmiljtxipport for 1988. fisken hau. 1988 (sernr. 1). barrett, r . t . , anker-nilssen, t., rikardsen, f., valde, k., rbv, n . & vader, w. 1987: the food, growth and fledging success of norwegian puffin chicks fraiercula arctica in 198& 1983. ornis scand. 18,13-83. barrett, r. t., fieler, r . , anker-nilssen, t. & rikardsen, f. 1985: measurements and weight changes of norwegian adult puffins fratercula arctica and kittiwakes rissa iridacryla dur ing the breeding season. ring. & m i g r . 6, 102-112. bradstreet, m. s. w. &brown, r . g . b . 1985: feeding ecology of the atlantic alcidae. pp. 263-318 in nettleship, d. n. & birkhead, t. r. (eds.): theatlaniicalcidae. academic press. burger, a . e. & simpson, m. 1986: diving depths of atlantic puffins and common murres. a u k 103, 828-830. corkhill, p. 1973: food and feeding ecology of puffins. bird study 20, 207-220. erikstad, k. e., mourn, t. & vader, w. 1990: correlation between pelagic distribution of common and briinnich’s guillemots and their prey in the barents sea. polar research threshold around a scale of 40 nautical miles. the 8 , p m 76 t . anker-nilssen & s . h . lorentsen furness, r. w. & barrett, r. t. 1985: the food requirements and ecological relationships of a seabird community in north norway. ornis scand. 1 6 , 305-313. hamre, j . 1988: some aspects of the interrelation between the herring in the norwegian sea and the stocks of capelin and cod in the barents sea. i c e s c . m . 1988/h:#2, 15 pp. harris, m. p. 1976: lack of a ‘desertion period’ in the nestling life of the puffin fratercula arctica. ibis 118, 115-118. harris, m. p. 1984: the puffin. t . & a . d. poyser ltd., calton. 224 pp. heinemann, d., hunt, g. & everson, i. 1989: the distribution of marine avian predators and their prey, euphausia superba, in the branfield strait and southern drake passage, antarc tica. mar. ecol. progr. ser. 58, 3-16. hunt, g. l., jr. & schneider, d. c. 1987: scale-dependent processes in the physical and biological environment of mar ine birds. pp. 7-41 in croxall, j. p. (ed.): seabircjs feeding ecology and ro[e in marine ecosystems. cambridge univ. press. jakobsson, j. 1985: monitoring and management of thc north east atlantic herring stocks. can. j . fish. aquat. sci. 42 (suppl. 1). 207-221. lid, g. 1981: reproduction of the puffin on r ~ s t in the lofoten islands in 1964-1980. fauna noru. ser. c, c i n c h 4 , 3c-39. myrberget, s. 1962: contribution to the breeding biology of the puffin, fratercula arctica (l,), eggs, incubation and young. medd. stat. uiltund. ser. 2 (ii), 1-51. pearson, t. h. 1968: the feeding biology of sea-bird species breeding on the farne islands, northumberland. j . anim. ecoi. 37, 521-552. piatt, j. f. & nettleship, d. n. 1985: diving depths of four alcids. auk 102, 293-297. r~ttingen, i. 1985: norwegian investigations in 1984-1985 on juvenile herring. jces c. m. 1985/h: 53, 1-5 (mimeo). schneider, d. c. & piatt, d. 1986: scale-dependent correlation of seabirds with schooling fish in a coastal ecosystem. mar. ecol. progr. ser. 32,237-246. schneider, d. c., pierotti, r. & threlfall, w. 1990: alcid patchiness and flight direction near a colony in eastern newfoundland. avian biol. (in press). sundby, s. 1984: influence of bottom topography on the cir culation at the continental shelf off northern norway. fiskdir. skr. ser. hauunders. 17, 501-519. sietre, r., sundby, s. & loeng, h. 1979: en del fysisk oseanografiske trekk langs den nordlige del av norskekysten. pp. 45-66 in anon. (ed.): om uirkninger au oljeforu rensninger i nordlige farvann. foh-report i, 1979, forsk ningsprogram om haujorurensninger, oslo. tait, r. v. 1981: elements ofmarine ecology (3rd ed.). but terworths, london, boston. tasker, m. l., hope jones, p., dixon, t . & blake, b. f. 1984: counting seabirds at sea from ships: a review of methods employed and a suggestion for a standardized approach. auk tschanz, b. 1979: zur entwicklung von papageitaucherkuken fratercula arctica in freiland und labor bei unzulanglichem und ausreichendem futterangebot. fauna noru. ser. c, c i n c h 2 , 7cl94. 101, 561-571. vegetation re-establishment in polar “lichen-kill” landscapes: a case study of the little ice age impact esther levesque & josef svoboda it has been accepted that the extremely sparse vegetation currently observed in canadian polar deserts is due to prevailing unfavourable climatic conditions, inhibiting plant establishment, growth and survival. less considered in the literature is the additional antagonistic factor of episodic adverse climatic anomalies. such was the most recent little ice age (lia) cooling which caused a setback to, or even large scale extinction of, high arctic plant communities that had taken centuries to develop. the lia brought about new glacial advances, expansion of permanent snow banks and formation of ice crusts over entire landscapes. the newly formed ice (and snow) killed the underlying vegetation, thus creating what is in the geological literature referred to as “lichen-kill zones.” in these zones the current plant diversity and abundance are exceedingly low and the plants are all relatively young and even-aged, factors which all point to their recent origin. here we maintain that this vegetation has not yet reached equilibrium with the present prevailing climate and that it is still in an initial stage of succession. we present results of eight upland sites sampled in the vicinity of alexandra fiord lowland, ellesmere island, canada, to demonstrate the slow recolonization process that has been occurring within the last 100-150 years after the lia termination. the widespread presence of the “lichen-kill” zones throughout the canadian polar regions reflects the extent and destructive nature of even minor climatic cooling on vulnerable polar ecosystems. e. le‘vesque, de‘pt. de chimie-biologie, universite‘ du que‘bec a trois-rivilres, c.p. 500, que‘bec, g9a 5h7 canada; j. svoboda, dept. of botany, university of toronto, mississauga, ontario, l5l ic6 canada. introduction central ellesmere island is mountainous and still partially glaciated (fig. 1). until 8 to 6 k y a , a continental ice sheet covered most of the island (bradley 1990). following the large-scale ice retreat, the primary tundra vegetation advanced from the south and established locally from propagules imported from the nearby ice-free refugia. in coastal regions it also returned from vegetated coastal shelves exposed during the ice age due to the lower sea level (murray 1995). this post-glacial (early holocene) vegetation was probably quite abundant, especially during the warm hypsithermal period (4-6 kya). however, it suffered repeated setbacks during the later cold climatic periods. present canadian polar deserts are ecologically marginal habitats for the estab lishment of higher plants. these polar deserts have minimal lichen and bryophyte abundance, and, on average, less than 5 % vascular plant cover. they are also low in species richness (bliss & matveyeva 1992). during the most recent climatic cooling called the little ice age (lia), ca. 1430-1850 a d (gribbin & lamb 1978), neoglaciation took place over the entire high arctic and many high mountain regions. extensive snow patches and ice crusts developed or expanded on high arctic uplands causing large segments of the vegetation to perish. these areas, now snowand ice-free once more, are clearly visible as pale stretches of land (fig. 2 ) . though all vegetation perished under the persisting blanket of snow and ice, since crustose lichens dominate old rock surfaces and give them a distinctly dark colour, landscapes lbvesque & svoboda 1999: polar research 18(2), 221-228 22 1 7a’w 7a’w fig. 1 . map of central ellesmere island. canada, indicating the major sampling area near alexandra fiord and sites with (filled circles) and without (empty circles) higher plants. which now appear bleached on photographs have been referred to in the literature as mere “lichen kill zones” (dyke 1978). after the ice retreat, remnants of the killed plants weather away and disappear without a trace within a few years. in some areas entire ancient plant communities are currently being released along the margins of a melting ice. for example, bergsma et al. (1984) documented emergence of well-preserved but dead plants at the melting front of an outlet glacier at alexandra fiord (see below) which during the lia period had advanced several hundred metres below its present position. inter estingly, the released ancient plant community had a higher representation of dryas integrifolia while the extant re-invading community is richer in cassiope tetragona, indicating drier habitat con ditions during the pre-lia period compared to those at present. havstrom et al. (1995) analysed preserved pre-lia shoots of c. tetragonu from the same locality and found that shoot growth and flowering were significantly lower in comparison to the plants alive today. havstrom et al. also calculated that the summer temperature during the period preceding these plants being entombed was 0.7”c lower than that at present. these plant communities may have been growing for many decades during the colder and drier lia climate before the outlet glacier reached and buried them. this paper presents information on the impact of lia on vegetation and the limited progress of plant re-establishment following the end of this minor climatic cooling period. eight upland sites in the vicinity of alexandra fiord, ellesmere island, canada, were studied. methods to demonstrate the impact of the lia on polar desert plant communities, an extensive four-year fig. 2. granitic upland and mountain slopes showing the extensive light-coloured “lichen-kill” zones contrasting with the darker pre-lia lichen covered landscape at 79”n, ellesmere island. canada. 222 vegetation re-establishment in polar “lichen-kill” landscapes table 1. the general (date of sampling. longitude. latitude, altitude and substrate type) and vegetation characteristics (vascular species diversity, cover [ a ] and density [plantslm']; ground covering bryophyte and lichen cover [%i) of eight upland sites in the proximity of alexandra fiord lowland. ellesmere island, canada. lichen cover was dominated by black lichen mixed with other cryptoganis in a cryptogamic crust: nia = not available; p = present on the site but exact cover not determined; tr = trace. rare on the site. site n2 n3 n5 e l s 1 ag ad b1 general characteristics date latitude ( n ) longitude ( w ) altitude ( m asl) substrate typc vegetation vascular species richness vascular plant cover ( % ) vascular plant density (piants/m') bryophyte cover (%) lichen cover (%) 28/07/93 78 46'14 75' 17'47 962 granitic 0 0 0 0.9 2 . 2 28/07/93 78'44'55 75' 06'00 812 granitic 9 0.5 6.6 0.2 2.6 28/07/93 78 44'55 75 06'00 i003 granitic 0 0 0 p 0 2 1 107190 78 51' 75"38' 818 granitic i 1 1.9 n/a 14.4 33.0 22/07/90 78"48' 75"58' 786 granitic 8 0.5 9.1 0.1 0.2 04/07/92 7 8 w ' 76"01' 540 granitic 12 11.2 66.4 3.5 50.3 04/07/92 78"51' 76'00' 540 carbonate 8 5.2 27.2 0.1 3.3 16/07/90 7 9 0 3 ' 75"00' 608 carbonate 8 0.5 16.5 tr 0.2 research programme was conducted in central ellesmere island, canada, during which over 80 upland and mountain localities were visited and systematically surveyed. of these, eight sites surrounding the alexandra fiord lowland (78"53'n, 75"55w) were selected for this case study. in contrast with the partially glaciated and mostly barren uplands, some reaching elevations over 1000 m, the lowland supports a relatively rich and diverse flora. the 8 km2 locality represents an oasis within an ice-covered and bare ground desert (svoboda & freedman 1994). three of the eight selected sites were located on rugged, hard rock nunataks, protruding through the ice of glaciers that descended into the lowland (fig. 1). the n2 site (962 m a d ) and, a little further east, sites n3 (812masl) and n5 (1003 masl), were situated to the south-east of the alexandra fiord lowland, near the saate glacier. the fourth site, e l at 8 12 m asl, was located near the margin of an ice cap remnant, topping a high plateau at the eastern side of the lowland. this small ice cap, captured on a 1959 airphoto, and still present during the 1990 survey, has now almost comple tely disappeared. three of the remaining sites were selected on the upland surrounding the western side of the lowland. two of these, both at ca. 540mas1, were close to each other but had different substrates. site ag was on granite while ad was on carbonate rock overtopping the granite. the third one, s1 at 786 m asl, was on the same upland slope but much higher and closer to the ice margin of a wide descending glacier. finally, the eighth site, b 1 at 608 m asl, was a carbonate rock plateau at bache peninsula, at the north side across the fiord (fig. 1 ) . general site characteristics are presented in table 1. all these sites showed signs of having been covered by ice during the lia. the nunatak sites (n2. n3 and n5) and sites e l and s1 were in close proximity to ice margins and no macro-lichens were yet visible on the exposed rocks, suggesting their having been released from ice during the last two or three decades. the three other sites (ag, ad and b1) were probably released earlier since some lichens were growing on the rocks (though fewer than in the lowland) and larger long-lived plants were growing on the sites (e.g. 5'ali.x arcticn and saxifraga oppositifolia). in 1990-93, vegetation and soil of all studied polar desert sites were thoroughly surveyed. in particular, at each site the vascular plant cover and density were measured with randomly laid quad rats (50 cm x 50 cm) using a modified abundance scale specifically designed to accurately assess sparse vegetation (lcvesque 1996). total lichen and bryophyte cover and ground area with fine material were also determined. at some sites the ground surface was coated by a cryptogamic crust described by gold & bliss (1995) from similar polar desert sites at devon island. the cover of this crust was included in the total lichen cover. the number of quadrats sampled per site ranged from 15 to 129 depending on the site heterogeneity and lkvesque & svoboda 1999: polar research 18(2). 221-228 223 table 2. the site specific vascular plant cover (%) of six upland sites studied near alexandra fiord, ellesmere island. data are presented as percentage of total number of quadrats sampled during the 5 to 8 hours survey sampling; tr = represents species found on site but not in sampled quadrats; occ. = occurrence of species out of the six sites. nomenclature follows porsild & cody (1980). site species n3 e l s 1 ag ad b1 occ. bruvu purpurscens curduntine bellidifoliu cussiope tetragonu cerustium cf urcticum drabu corymbosa druba lucteu druba nivulis drubu subcapitato dryus integrifaliu luzulu urcticu luzulu confusu minuartin rubdla oxyriu digvriu pupuver rudicutum pediculuris cf urcticu phippsiu ulgidu pou urcticu puccinelliu bruggernunnii sulix urcticu suxifruga cuespitosu suxifrugu cernuu suxifrugu rzivulis suxifrugu opposit(fofoliu saxifraga tricuspidutu <0.01 0.08 0.01 0.01 tr 0.04 0.43 tr 0.01 0.07 0.75 tr 0.08 0.01 < 0.0 1 0.31 tr 0.40 0.26 tr 0.02 tr tr 0.02 0.13 tr tr 0.28 0.02 0.03 0.02 0.20 0.69 0.04 0.04 0.01 0.47 0.30 8.49 0.87 0.08 0.65 0.01 0.01 tr 3.03 tr 1.40 0.05 0.03 0.12 0.14 0.02 0.02 0.08 0.04 1 3 1 3 3 1 1 4 2 2 4 2 1 6 2 2 2 1 3 i 2 2 6 1 number of quadrats sampled: 129 93 15 25 25 30 the time available (table 2). in addition, a complete vascular species list was established. nomenclature follows porsild & cody (1980). soil samples (top 10 cm; n = 3) were collected and pre-sifted on site (4 mm). in the laboratory the soils were dried to constant weight (60°c) and the fine fraction (< 2 mm) analysed. total organic carbon (oc; n = 2) was determined by wet combustion method (nelson & sommers 1996). and extractable phosphorus (p; n = 3) by a weak hydrochloric acid method (bray & kurtz 1945). results are presented as percent or ppm of the small soil fraction (< 2 mm). results and discussion as expected by nature of their arcto-alpine position, the studied localities supported very little vegetation (table 1). in fact, the two highest sites, at 962 m and 1003 m asl, had no vascular plants at all. these sites were either released from ice quite recently or they were situated above the present altitudinal limit for vascular vegetation at this high latitude. vascular plant cover ranged from 0.5% to 11% and decreased with increasing altitude, with a break point at ca. 600 m as1 (fig. 3). bryophyte cover was scanty (except at the e l site, with 14%). the lichen cover, present mostly as a component of the cryptogamic crust, showed correlation with moisture availability. vascular species richness of mere 8-10 species was low and did not vary greatly among sites (table 1). only two vascular species, smifraga oppositifolia and papaver radicutum were common to all six vegetated sites, followed by draba subcapitata and luzula confisa, present at four of the sites (table 2 ) . the marked difference in the vascular plant cover between the low altitude sites ad and ag (cover > 5 % ) and the higher altitude sites (cover <2%) was not associated with an increase in species richness. the difference depended on the relatively high cover of sulix urctica at sites ag 224 vegetation re-establishment in polar “lichen-kill” landscapes 15 a $ 10 t y > 5 0 0 0 1 .o n 0 0.5 0 0.0 12 n g 8 4 4 a y 0 ag ad e l 0 61 s1 6 nz n5 e . 0 . n3 f * e i, o o 500 600 700 800 900 1000 i100 altitude (m a d ) f i g . 3 . total vascular plant cover (s), soil organic carbon (%; n = 2) and extractable phosphorus (ppm: n = 3) of eight sites sampled in the vicinity of alexandra fiord lowland. mean f se: full circles represent granitic sites and the empty circles carbonate rocks sites. soil parameters were calculated for the fine fraction of the soil ( < 2 mm) which represents ca. 5 % ) of the soil volume. and ad and the slightly larger size of saxifraga oppositifolia plants, especially at site ad (table 2). as described in previous studies on ellesmere island, we also noted a difference in plant abundance associated with the substrate, the vegetation on carbonate rocks being generally more sparse (batten & svoboda 1994; lcvesque 1997). plant density varied greatly and was inversely correlated with the altitude (table 1). the two lower sites, again, had the highest values (66 and 27 plants/m2 for ag and ad, respectively). this suggests that plant establishment was more successful at the lower sites. this could be associated with generally more favourable condi tions for plant growth for sites ag and ad. however, site b1, which was only slightly higher than sites ad and ag, had only 0.5% cover but 16.5 plants/m’. this plant density would suggest either a higher recruitment rate on site b 1 than on sites n3 and s l or a longer time since ice retreat, allowing greater plant recruitment. since plants remain small and total cover remains < 1 % on this dolomitic plateau, environmental conditions are considered particularly limiting to plant growth and an earlier ice retreat would explain the higher density observed. bergsma et al. (1984) present a photo of the ice front of the glacier releasing the entombed plants at alexandra fiord. the ground moraine shows two distinct retreat zones. the first, adjacent to the ice front, has been expanding since about 1948. the second, more distant, zone marks the glacier’s maximum lia advance and could be dated to 80-100 years earlier, i.e. to the mid-1800s. there is a distinct time hiatus between the two zones suggesting that the glacier stopped retreating for several decades prior to 1948. consequently, the lower stands on the plateau must also have become free from ice prior to the upper slope stands, thus allowing their communities more time to develop. the coarse, very poorly developed soils con tained a large proportion of angular boulders and pebbles. they all fit the category of lithic regosolic cryosols, following muc et al. (1994). organic carbon generally decreased with altitude, parallel ing the diminishing plant cover and biomass. the phosphorus availability in the fine soil fraction was lowest on sites with the highest plant cover at low altitude (fig. 3 ) . our values are comparable to those published by muc et al. (1994) for the alexandra fiord area. these authors linked the low phosphorus availability in the lowland (1-7 ppm for various plant communities) with the high organic content of these soils, whereas they obtained higher values of available phos phorus in the soils of the sparsely vegetated polar deserts (up to 64ppm). nutrients tend to form organic complexes and are unavailable to plants at the more productive sites. this process keeps draining the available nutrients from the soil into the sink of the slowly accumulating standing crop and litter, especially since mineralization pro cesses are extremely slow at these latitudes (nadelhoffer et al. 1992). two other plant community studies were conducted on alexandra fiord uplands prior to our survey of the polar plateaux. batten & svoboda (1994) gathered data on plant cover and frequency from 26 sites, of which about 10 were situated above the 600m contour line and could have been, therefore, altitudinally comparable with our sites. by using principal component analysis (pca) batten & svoboda recognize seven community types. however, these commu l t v e s q u e & svoboda 1999: polar research 18(2j, 221-228 225 nity types widely range in elevation. thus, a saxifraga oppositifolia-luzula based community was found at elevations 520-920 m; cassiope dominated community occurred at elevations 630-870 m, etc. since the objectives of their study were different from ours, all collected data were pooled to generate a matrix for the pca in order to obtain the desired community types. as a result, information on individual sites for a meaningful comparison with our sites is not available. more relevant with respect to our study is the work of bliss, henry et al. (1994) at the western plateau. eleven stands of vegetation were sur veyed for plant diversity and cover down the long slope (ca. 750-500m) along the west arm glacier. the total vascular plant cover ranged from 0% (the highest four stands) to 12.6% at the granitic rim circumscribing the dolomitic “dome” on the east end of the plateau; this last stand is comparable to our site ag (1 1.2%). although bliss, henry et al. make no attempt to correlate the community data with the time the surveyed sites were released from ice or snow, two conclusions can be made in retrospect, both supporting our findings: 1) the lower sites were released earlier than the uppermost sites where more areas are being still open to plant colonization; 2) the environmental conditions (especially the micro climate) of the higher elevated sites are less favourable (cf. svoboda & henry 1987) than those at the altitudinally lower stands, hindering plant establishment, successional progress and standing crop accumulation (bliss, henry et al. 1994). fig. 4 . general features of site n3 (812m ad), with a large flowering lurrtla confusn plant, near alexandra fiord, ellesmere island, canada. note that the rocks are free of macro lichens. there are many factors which hamper vegeta tion development in marginal polar environments: shorter and colder growing season (even in comparison with the latitudinal normals), extreme ly low nutrient availability and drought (e.g. bliss, svoboda et al. 1984; gold & bliss 1995; lcvesque et al. 1997), inadequate supply of viable propa gules (svoboda & henry 1987), and consequently meagre viable seed bank with less than 100 seeds/ m2 (lcvesque & svoboda 1995). also natural disturbance such as needle ice, cryoturbation, grazing, trampling and erosion often uproot and eliminate the already established plants (forbes 1996; anderson & bliss 1998). the inhospitable polar desert environment at the alexandra fiord uplands acts as a barrier for many species, which flourish in the lowland below. out of 91 vascular species listed for alexandra fiord lowland by ball & hill (1 994), batten & svoboda (1994) list 34 species and bliss, henry et al. (1994) 19 vascular species (in quadrats only) in their respective upland sites. a total of 24 vascular species was identified in our eight sites. yet, surprisingly, we observed that some plant individuals growing on high nunataks and plateaux (sites n2, n3, n5, e l and s1) formed vigorous healthy clusters with prolific blooms while the surrounding rocks were still free from crustose macro-lichens. these plants had few leaf scars on their short shoots, revealing their young age. which corroborated the notion about their recent establishment (fig. 4). closeness to the water source (melting ice) and flush of nutrients 226 vegetation re-establishment in polar “lichen-kill” landscapes available in the freshly exposed soil have tem porarily compensated for the cold microclimate. in time, after the glacier retreats further up the slope, the soil dries out and the nutrients become depleted, these plants will slowly lose their vigour and a significant portion of standing dead will appear in their clumps. the plant assemblage will eventually become indistinguishable from typical polar desert vegetation. colonization success is a function of seed availability, supporting environment and the time period since the site has become available to plant reinvasion (svoboda & henry 1987). even at 80"n, productive meadows developed in protected irri gated valleys (e.g. svoboda & freedman 1994). however, these more lush vegetation such as the alexandra fiord lowland or the 8 0 k m long sverdrup pass at central ellesmere island (berger on & svoboda 1989) were deglaciated 5-7 kya and were spared the lia neoglaciation (muc et al. 1994). these richly vegetated areas with more developed soils and higher organic carbon content in the soil represent less than 10% of the island's ice-free area. polar deserts and semi-deserts cover the majority of the island (bliss & matveyeva 1992). since the retreat of the continental ice sheet (not yet fully completed at ellesmere island), vegetation that had developed at ice-free uplands was decimated by several neoglaciations of which the most recent was the lia period (svoboda 1982). we found no dead pre-lia plants at the studied upland sites. if there were any, they have weathered away over the decades after their release from ice. thus, no direct evidence of the pre-lia vegetation on these uplands is available so far. the only indication of ancient vegetation may come from soil organic carbon. although the values were very low, in view of the extremely low extant plant productivity and biomass, accumula tion of the detected soil organic carbon must have taken a very long time. hence, we conclude that the carbon extracted from these soils must, in part, have been incorporated in the pre-lia period. even though we know not what vegetation grew on alexandra fiord uplands prior the lia. it seems evident that the recovering vegetation has not reached an equilibrium with the climate of today. while some areas with persistently adverse conditions (dry, wind-swept ridges such as site b1) may resist the development of a more significant plant cover, many other areas have a potential of supporting a more diverse and abundant vegetation providing enough time is allowed to elapse before another major disturbance occurs. what could be the impact of the ongoing global warming on these vast deglaciated and still deglaciating landscapes? biological processes (e.g. plant growth, nutrient mineralization) take place more rapidly in a more favourable environ ment, resulting in a much faster successional progress within the same time frame. the active layer would deepen, making new nutrients and moisture available to expanding established plants and to new invaders. polar deserts may upgrade to semi-deserts and semi-deserts may develop into a more fully vegetated tundra. however, such climatic changes may be associated with more severe surface drought, which could hinder vegetation succession. they may, in contrast, bring about more abundant winter snowfall, which could further delay the short growing season. clearly, even a minor climatic anomaly may have an extensive and lasting impact on marginal polar ecosystems. acknowledgenients. this contribution is part of a larger study of polar desert vegetation at ellesmere island. the field work took four seasons to complete. we had the pleasure to collaborate with a large number of enthusiastic people, in particular with a. a. ferguson, g. a. jones, a. p. kwiecien and p. van wassenaer. logistic support and helicopter transporta tion to numerous upland and mountain sites was provided by the polar continental shelf project (canada, pub. 02599). financial support from the following canadian organizations is gratefully achowledged: natural sciences and engineering research council research grants to j . s.; northern science training program travel and field expense grant for e. l. and field assistants and fonds fcar, tri-councils of canada and jeanne f. goulding fellowship (university of toronto) to e. l. we also thank alison dias for her skilful help with the preparation of fig. 1. references anderson, d. g. & bliss, l. c. 1998: association of plant distribution patterns and microenvironments on patterned ground in a polar desert, devon island, nwt. canada. arct. alp. res. 30. 97-107. ball, p. & hill, n. 1994: vascular plants at alexandra fiord. in j. svoboda & b . freedman (eds.): ecology of a polar oasis. alexandra fiord, ellesmere island. canada. pp. 255-256. toronto: captus university publications. batten. d. s . & svoboda, j. 1994: plant communities on the uplands in the vicinity of the alexandra fiord lowland. pp. 97-110. in 1. svohoda & b. freedman (eds.): ecology o j a polor oasis, alexandra fiord, ellesmere island, canada. pp. 97-1 10. toronto: captus university publications. bergeron. j. f. & svohoda. j. 1989: plant communities of sverdrup pass, ellesmere island, nwt. the muskox 37, 76-85. l t v e s q u e & svohoda 1999: polar research 18(2). 221-228 221 bergsma, b. m., svoboda, j. & freedman, b. 1984: entombed plant communities released by a retreating glacier at central ellesmere island, canada. arctic 37, 49-52. bliss, l. c. & matveyeva, n. v. 1992: circumpolar arctic vegetation. pp. 59-89 in f. s. chapin i11 et al. (eds.): arctic ecosystems in a changing climate: an ecophysiological perspective. san diego: academic press. bliss, l. c., svoboda, j. & bliss, d. i. 1984: polar deserts, their plant cover and plant production in the canadian high arctic. holarctic ecol. 7, 305-324. bliss, l. c., henry, g. h. r., svoboda, j. & bliss, d. i. 1994: patterns of plant distribution within two polar desert landscapes. arct. alp. res. 26, 46-55. bradley, r . s. 1990 holocene paleoclimatology of the queen elizabeth islands, canadian high arctic. quat. sci. rev. 9, 365-384. bray, r. h. & kurtz, l. t. 1945: determination of total, organic, and available forms of phosphorus in soils. soil sci. 59, 3 9 4 5 . dyke, a. s. 1978: indications of neoglacierization on somerset island, district of franklin. current research, part b ; geological survey canada, scientific and technical notes, paper 78-1b, 215-217. forbes, b. c. 1996: plant communities of archeological sites, abandoned dwellings, and trampled tundra in the eastern canadian arctic: a multivariate analysis. arctic 49, 141-154. gold, w. g. & bliss, l. c. 1995: water limitations and plant community development in a polar desert. ecology 76, 1558-1568. gribbin, j. & lamb, h. h. 1978: climatic change in historical times. in j. gribbin (ed.): climatic change. pp. 68-82. cambridge: cambridge university press. havstrom, m., callaghan, t. v., jonasson, s. & svoboda, j. 1995: little ice age temperature estimated by growth and flowering differences between subfossil and extant shoots of cassiope tetragonu, an arctic heather. funct. ecol. 9, 650-654. ltvesque, e. 1996: minimum area and cover-abundance scales as applied to polar desert vegetation. arct. alp. res. 28, 156-162. ltvesque, e. 1997: plant distribution and colonization in extreme polar deserts, ellesmere island, canada. phd thesis, dept. of botany, university of toronto. 331 pp. lbvesque, e. & svoboda, j. 1995: germinable seed bank from polar desert stands, central ellesmere island, canada. in t. v. callaghan et al. (eds.): global change and arctic terrestrial ecosystems. ecosystems research report 10. pp. 97-107. luxembourg: european commission. ltvesqne, e., henry, g. h. r. & svoboda, j. 1997: phenological and growth responses of papaver radicatum along altitudinal gradients in the canadian high arctic. glob. change biol. 3 (suppl. i ) , 125-145. muc, m., svoboda, j. & freedman, b. 1994: soils of an extensively vegetated polar desert oasis, alexandra fiord, ellesmere island. in j. svoboda & b. freedman (eds.): ecology of a polar oasis, alexandra fiord, ellesmere island, canada. pp. 41-50. toronto: captus university publications. murray, d. f. 1995: causes of arctic plant diversity: origin and evolution. in f. s. chapin 111 & c. korner (eds): arctic and alpine biodiversity, patterns, causes and ecosystem conse quences. pp. 21-32. berlin: spinger. nadelhoffer, k. j . , giblin, j. r., shaver, g. r. & linkins, a. e. 1992: microbial processes and plant nutrient availability in arctic soils. in f. s. chapin 111 et al. (eds.): arctic ecosystems in a changing climate: an ecophysiological perspective. pp. 281-300. san diego: academic press. nelson, d. w. & sommers, s. e. 1996: total carbon, organic carbon, and organic matter. in d. l. sparks (ed.): methods of soil analysis. part 3. chemical methods. pp. 961-1010. madison (usa): soil science soc. of america and american soc. of agronomy. porsild, a. e. & cody, w. j. 1980: vascular plants of continental northwest territories, canada. 667 pp. ottawa: national museums of canada. svoboda, j. 1982: due to the little ice age climatic impact, most of the vegetative cover of the canadian high arctic is of recent origin: a hypothesis. abstract. proceedings ofthe 33rd alaska science conferenceiaas arctic division. pp. 206. fairbanks: american assoc. for the advancement of science. svoboda, j. & henry, g. h. r. 1987: succession in marginal arctic environments. arct. alp. res. 19, 373-384. svoboda, j. & freedman, b. 1994: ecology of a polar oasis, alexandra fiord, ellesmere island, canada. 268 pp. toronto: captus university publications. 228 vegetation re-establishment in polar “lichen-kill’’ landscapes factors affecting the seed-setting success of dryas octopetala in front of broggerbreen (brogger glacier) in the high arctic, ny-ilesund, svalbard naoya wada to determine the factors restricting plant reproduction in front of a glacier, the gender expression and seed production of dryas octopetala l. (rosaceae) were observed, as well as the grazing pattern ,of reindeer on flowers, near broggerbreen (brogger glacier), which is near ny-alesund (78"55'n, 11 "56'e), svalbard. three hundred shoots with flowers and flower buds were randomly tagged in early july 1996. between then and the end of flowering i n late july, 100 (33%) flowers and buds were grazed by reindeer. out of the surviving flowers, 145 (76%) shoots had hermaphrodite flowers, while 45 (24%) shoots had male flowers without a developed gynoecium. male flowers, which appeared later than hermaphrodite flowers in the population, were significantly smaller than hermaphrodite flowers in dry weight. in the hermaphrodite flowers, moreover, smaller flowers showed lower dry-weight allocation to the gynoecium as compared to larger flowers. during the observation, hermaphrodite flowers did not produce any developed seeds under a natural condition (0% seed-set). cross-pollinated flowers showed 8% seed-set. on the other hand, flowers which were artificially warmed in small greenhouses during the flowering period showed 60% seed-set, regardless of cross-pollination or autodeposition of pollen from anthers to stigma (self-pollination). thus, it was found that grazing, gender variation in relation to the length of the growing season and the flower size, and in the flowering period low temperature rather than pollinator limitation strongly affected the seed production of d. octopetala in the population studied. n. wada, dept. of biosphere science, f a d 8 of science, toyarna university, toyarna 930-8555, japan. introduction global climatic warming is expected to have a stronger impact on arctic terrestrial ecosystems than on lower latitudinal ecosystems (maxwell 1992). climatic warming in the arctic will promote deglaciation, exposing bare ground in front of glaciers. to understand ecological succes sion in deglaciated lands, it is important to clarify how spores or seeds invade deglaciated locations and what factors limit the seed production of plants found around glaciers. environmental conditions in the high arctic are extremely severe for the growth and reproduction of tundra plants (kelley & weaver 1969; bell & bliss 1980). cold environments may strongly restrict various kinds of temperature-dependent physiological activities affecting photosynthesis. fertilization and reproduction. low temperature also affects the activities of insect pollinators (kevan & baker 1983; totland 1994a), resulting in fewer opportunities for cross-pollination and therefore restricted gene flow. thus, biotic and abiotic factors may greatly affect sexual reproduc tion and seed production, especially in plants inhabiting areas in front of glaciers. this study examines the effects of cross-pollination and artificial warming on seed production. its purpose was to clarify how these factors affect seed-setting success in a circumpolar plant species, dryas octopetala l., in frpnt of braggerbreen (brogger glacier), near ny-alesund, svalbard. the inten sity of reindeer's grazing on dryas flowers was also examined to determine its influence on the reproduction of the plant. reindeer frequently forage not only on grasses, sedges and lichens wada 1999: polar research 18(2), 261-268 26 1 (jefferies et al. 1992) but also on the flowers of d. octopetala, saxijragu oppositifolia, s. nivalis and silene acaulis (wada, personal obs.). gender expression of some plant species varies along an environmental gradient and among habitat conditions (e.g. kudo 1997). under stress ful or resource-limited conditions for reproduc tion, smaller-sized plants have a higher rate of success in reproducing through the male function than through the female function (lovett doust & lovett doust 1988; klinkhamer & d e jong 1993; kudo 1993). in a preliminary survey, it was found that d. octopetala had two types of flowers: hermaphrodite and male flowers (wada et al. 1999). the present study reports on the phenolo gical and size differences between hermaphrodite and male flowers, as well as the gender variations within hermaphrodite flowers in relation to flower size. this study aims to clarify: i ) the number of flowers of d. octopetalu which are grazed or survive during the flowering period; 2) the effect of grazing animals on the spatial distribution of dryas flowers; 3) the effect of flower size on gender expression or allocation to female function; 4) the effect of factors such as pollen limitation and low temperature during a flowering period on seed production. finally, this paper discusses factors affecting seed-setting success from the onset of flowering to the fruiting stage. materials and methods study site the study site wac located ca. 1.5 km from the edge of broggerbreen (brogger glacier) !nd ca. 0.5 km from kongsfjorden, near ny-alesund (78'55'n, 1 ln56'e), svalbard. the monthly aver age temperatures of june, july and august 1996 were 1.9"c. 3.8"c and 3.5"c, respectively (data from norwegian polar institute). in early july 1996, a 10 m x 50 m plot was established on a ridge. this plot was dominated by d. octopetala but included salix polaris, saxifraga oppositijolia, silene acaulis, o q r i u d i g p a . polygonum vivipar ion and bryophytes. plant material (dtyus octopetala l . ) d. octopetalu is widely distributed in the low arctic in alaska (mcgraw 1985) and scandinavia and in the high arctic in svalbard, norway, greenland, and russia (hultcn 1959; rgnning 1969, 1996). this plant forms a cushion on the ground, and has one flower per terminal shoot. however, the cushion form is not always well defined, and it was difficult to determine indivi dual plants in the plot used in this study. the bowl shaped flowers show sun-tracking behaviour (flower heliotropism), resulting in high tempera ture in the gynoecium as compared to ambient temperature (kjellberg et al. 1982). this may be necessary for d. octopetulu to produce seeds in cold environments, suggesting a species sensitive to solar radiation and temperature in terms of its reproduction. flowering phenology and grazing pattern in the plot, 300 shoots (271 flower buds and 29 flowers) of d. octopetala were randomly selected and tagged on 1 1 july 1996. they were observed every day from the onset of flowering to the end, and the phenology of hermaphrodite and male flowers was recorded, as was the number of grazed flowers. because reindeer grazed on the dryas flowers but not the stalks (peduncles), the grazed flowers could be recorded by the remaining flower stalks on the shoots. on 10 august, a 4 m x 4 m quadrat was established in the study plot. the quadrat was divided into 64 0.5 m x 0.5 m subquadrats. grazed and non-grazed flowers and the leaf cover of d. octopetala were mapped in each subquadrat to clarify the effect of grazing on the spatial distribution of dryas flowers. the spatial pattern of initial flowers and grazed flowers was analysed using morishita's is index (morishita 1959), with the following formula: i & = n x x i ( x i i ) / n ( n i ) , where n is the number of subquadrats of a given size (e.g. 64 0.5 m x 0.5 m quadrats), xi is the number of flowers in a ith subquadrat, and n is the total number of flowers (in the 4 m x 4 m quadrat). id > 1 shows clumped distribution; i s = 1. ran dom distribution; i6 < 1, uniform distribution. i s was calculated at a different subquadrat size; 0.25 m2, 1 m2 and 4 m2 (for details see morishita 1959, 1962). the significance of i s > 1 or < 1 was tested by using f test ( d f = n 1. k'), calculated i = i 262 factors affecting the seed-setting success of dnus octopetula in front of broggerbreen with the following formula: f = [z6 (n 1) + tl n] / (tz 1). gender wriatioti of dryas flowers twenty-four hermaphrodite flowers and 20 male flowers were randomly collected in the study plot in late july 1996. in each flower, the length ( l ) and width ( w ) of four petals per flower were measured. individual petal area (pa) was calcu lated with the following formula: pa = (l x w ) x tc x 0.25, where each petal was estimated as an ellipse shape. after that, each flower was dissected into petal, androecium, gynoecium (hermaphrodite flowen), calyx and receptacle and dried for 48 hours at 8o’c. the dry weight of these parts was measured and compared between hermaphrodite and male flowers. furthermore, to clarify a variation of sex allocation based on dry weight within hermaphro dite flowers, “femaleness” was calculated with the following formula: femaleness = g w / (gw + aw), where g w is the dry weight of the gynoecium, and aw is that of the androecium (cf. lloyd 1980). in this study, femaleness was used as an indicator of the reproductive effort of female function, and the relationship between femaleness and the flower size (dry weight) was analysed to determine whether femaleness is size-dependent. effects of cross-pollination arid artificial nurmitig on seed production to determine whether seed production is restricted by pollen limitation or by low temperature, four treatments were conducted within the plot: 1 ) hand-pollination (hp). in which the gynoecium of dryas flowers was supplied with pollen collected from the other five flowers ( n = 25 flowering shoots): 2) netting (n), in which a flowering shoot was covered with fine polyester netting (mesh size < 1 mm’; n = 15) to exclude any pollen-transport ing insects; 3) warming (w), in which a flowering shoot was artificially warmed using a small greenhouse made of steel wire and vinyl sheeting ( n = 15); and 4) hand-pollination and warming (whp, tz = 15). the fine polyester nets and small greenhouses were set up on mature flower buds of dryus shoots from 16 to 20 july. in hp and hpw treatments, dryas flower buds were emasculated on 20 july, and cross-pollination was conducted when those petals completely opened on 24 july. on 4 august, all nets and greenhouses were removed when all petals dropped off the flowers. flower buds occurring near the greenhouses were tagged as controls ( n = 25). on 20 august. these shoots were collected, and the seed-set per flowering shoot was compared among treatments. following wookey, parsons et al. (1993), “seed setting” is defined as the number of fruiting shoots having one or more mature seeds with well developed feathery styles beyond the extent of the sepals. divided by the number of flowering shoots in each treatment. to confirm the warming effect of the small greenhouses, a small temperature data-logger was set up (stowaway tidbit, onset computer corporation) inside and outside the greenhouse on the ground. this measured the temperature at two-minute intervals from 1 to 8 august 1997. results and discussion grazing pattern and flowering phenologj in the tagged dtyas flowers, the onset of flowering occurred from early to late july. out of 300 reproductive shoots, 10 (3.3%) buds were im mature and did not bloom. one hundred (33.3%) flower buds and flowers were grazed by reindeer: 23 in the pre-flowering stage (flower bud), 73 in the flowering stage, and 4 in the post-flowering stage. reindeer tended to forage on dryas flowers on the 5th day (?sd 2 days), ranging from the 1st to the 1 1 th day ( n = 69), after their petals opened. thus, 110 (36.7%) shoots failed to produce offspring before producing seeds and fruits. grazing by reindeer had a strong impact on the spatial distribution of d t y s flowers. as shown in figs. 1 and 2, dryas flowers were initially distributed in small, clumped patches at 0.25 and i m2 scales. however, grazed flowers were more aggregated than initial flowers in both scales, indicating density-dependent predation on dryas flowers. because a high density of flowers results in a high probability of cross-pollination by attracting pollinators (thomson et al. 1982; sih & baltus 1987; totland 1994a), a density dependent grazing pattern might not only directly wada 1099: polar research 18(2), 261-268 263 c----l 0.5 m fig. i . spatial distribution of dryus flowers (0 = grazed flowers, n = 30; 0 = non-grazed flowers, n = 110) in the 4 m x 4 m quadrat. grey-shaded area = leaf cover of d p u s ocfopetulu; dotted area = gravel (bare ground). decrease the number of flowers potentially produc ing seeds and fruits but also indirectly reduce a chance of out-crossing i n the remaining (non grazed) flowers. phenological and size differences between hermaphrodite and male flowers and gender variation within hermaphrodite flowers in the tagged flower buds and flowers, 190 shoots succeeded in flowering without being grazed. however, 45 (23.7%) flowers did not have any gynoecium; that is, they were male flowers. the number of male flowers versus hermaphrodite flowers tended to be slightly higher i n late flowering shoots than in early flowering shoots (fig. 3). when 190 shoots were divided into two groups, early flowering shoots (defined as those which began to flower on or before 15 july) and late flowering shoots (after 15 july), the ratio of male flowers (22) to hermaphrodite flowers (90) was 0.24 i n early flowering shoots and 0.42 (231 55) in late flowering shoots. i n later flowering shoots or plants, the growing period may be insufficient for the completion of seed maturation, resulting in reduced seed production or low seed set (spira & pollack 1986; kudo 1991; totland ...., 0 1 i i i i 0 1 2 3 4 spatial scale (subquadrat size, m2) fig. 2. morishita’s i6 values for initial flowers (0) and grazed flowers (0) at the three spatial scales: 0.25 in’, 1 mz and 4 m’. the broken line shows i 8 = 1 (random distribution). ** = p < 0.01; * = p < 0.05. 1994b, 1997). the high ratio of male flowers to hermaphrodite flowers in later flowering shoots may reflect that reproduction through the female function is difficult for late flowering dryas flowers due to the short growing period. this selection pressure might strongly act on dryas flowers, resulting in a higher occurrence of male flowers in later flowering shoots. philipp et al. (1990) observed that d. integrifolia also had hermaphrodite and male flowers, and male flowers appeared later than hermaphrodite f’lowers in a population in greenland. however, because phe nological differences vary among populations 30 2 0 1 lo !3 z 10 10 15 20 25 30 35 days from 30 june & fig. 3. flowering phenology of hermaphrodite flowers (0, n = 145) and male flowers (0. i i = 45). 264 factors affecting the seed-setting success of d t y s octopetulu i n front of broggerbreen 0.8 0 u 1 2 6 10 14 18 22 26 flower size (dry weight, mg) fig. 4. (a] fiower size (dry weight) of male flowers aiid (b) hermaphrodite flowers, and ( c ) the frequency of malelall flowers (%) i n relation to the flower size. (philipp et al. 1990), further information concern ing several populations is required. dry weight was significantly lower in male flowers (mean & sd: 9.6 & 2.5 mg, n = 20) than in hermaphrodite flowers (16.9 f 2.3 mg, n = 24, see fig. 4). male flowers had a smaller petal area and lighter petal and androecium weight than hermaphrodite flowers (table i ) , suggesting lower investments to reproduction through male flowers. all flowers with a dry weight under 10nig were male shoots, while all flowers having a dry weight over 16 mg were hermaphrodite shoots. flowers ranging from 10 mg to 16 mg in dry weight were composed of both male and hermaphrodite shoots (fig. 4). according to the frequency distribution of dry weight. male flowers did not completely 0 m b 8 e o'21 0' 2.2 2.4 2.6 2.8 3 3.2 in flower weight (mg) f i g . 5. relationship between flower size (in flower weight = x ) and femaleness ( y ) i n hermaphrodite flowers of dryus ocfo p e t a h ( y = 0.306% 0.345, r = 0.573, ) i = 24, p = 0.0028). segregate from hermaphrodite ones; rather, the gender sequentially changed from a maleto female(hermaphrodite-) biased expression as flower size increased (fig. 4). moreover, dry weight allocation to the female function (female ness) vaned even within hermaphrodite flowers, and femaleness was positively correlated with flower size to a significant degree (fig. 5). thus, smaller flowers tended to allocate dry-matter investments into male organs (androecium) more than into female organs (gynoecium), as compared to larger flowers. with respect to size-dependence, this result supports a previous study by kudo (1993) in anemone debilis fish. according to molau (1993). d. octopetda has been recognized as a typical gynodioecious plant tuble 1. size differences between hermaphrodite (n = 24) and male flowers ( n = 20) of d p a s o c f o p m h (mean ? s d ) . the differences were analysed with student's t-test. hermdphrodi te male f-value p petal area (mm2)* 43.2 2 9.9 29.7 11.1 4.24 0.0001 petal weight (mg) 5.9 & 1.6 3.7 * 1.2 5.33 <0.0001 androecium weight (mg] 2.3 & 0.5 1.8 ? 0.6 3.66 0.0007 gynoeciuni weight (mg) 2.6 & 0.9 calyx and receptacle 6.0 ? 1.0 4.2 k 1.1 5.92 <0.0001 (mg) flower weight (mgj 16.9 k 2.3 9.6 k 2.5 8.74 <0.0001 *individual (mean, petal area per flower. wada 1999: polar research 18(2), 261-268 265 species, composed of a mixture of hermaphrodite and purely female shoots. however, such a gynodioecy type was not found in this study, but male shoots in addition to perfect hermaphrodite shoots on the same cushions (individuals) were frequently observed. this suggests an andromo noecy or androdioecy of d. octopetala, as reported by philipp et al. (1990) for d. integrifolia. although further detailed studies are needed to clarify the variation of sex expression in d q a s species in relation to various environmental conditions, d. octopetala might have high pheno typic and genetic variations for floral sex alloca tion, as sh$wn in this study. in ny-alesund, wookey, parsons et al. (1993) and wookey, robinson et al. (1995) examined seed-sets of d. octopetala in various simulated environments. however, it was unclear whether a seed-set was obtained by the number of fruiting shoots divided by the number of flowering shoots minus the number of male flowering shoots. if these studies did not exclude the number of male flowering shoots, they would have underestimated the actual seed-set. it is important to examine the variations of the number of male flowers among experimental treatments and/or from year to year when assessing the differences of the seed-sets under various environmental conditions. efects o j cross-pollination arid artificial warming on seed production the small greenhouses increased the mean tem perature by ca. 1.3'c, maximum 8.7"c and minimum -1.4'c, as compared to the outside temperature from 1 to 8 august 1997 ( n = 5040 measuring points, fig. 6). the results of pollina tion and warming effects on seed-set are shown in fig. 7. in this study, i n the year 1996, dryas flowering shoots did not produce any seeds in the control shoots ( n = 25) or in 145 tagged hermaph rodite flowering shoots. the cross-pollinated and net-covered shoots showed 8% and 6% seed-set, respectively, while the artificially warmed shoots showed 60% seed-set regardless of cross-pollina tion or autodeposition (internal transfer of pollen from anthers to stigma without any external vector). this shows the self-compatitility of d. octopetala in a population in ny-alesund, as previously reported by molau (1993) in a natural population in latnjajaure (68"22'n, 18"29'e), in northernmost sweden. the net-covered flowering shoots succeeded in producing a small portion of 0 1 i 1 i i i i i q -2 i i 1 i 1 i i 118 218 318 418 518 618 718 818 date (1997) f i g . 6. (a) temperature ("c) inside (folid line) and outside (dashed line) the small greenhouse, and (b) the difference ( a temp.). seeds, probably because the fine net cover increased temperature slightly by reducing wind. wookey, parsons et al. (1993) also demonstrated that d. octopetala showed 60% seed-set by an artificial warming treatment using open-topped 80 i . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . w c., . . . . . . . . . . . . . . . . . . . . . . !i 40z .............. 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c n hp w whp treatments f i g . 7. effects of pollinator exclusion (netting, n j , cross pollination (hand pollination, hp). artificial warming ( w ) . combination of cross-pollination and artificial warming ( w h p ) on seed-set (%)of d p a s flowers. c shows control. numerals i n parentheses on the bars show number of samples. 266 factors affecting the seed-setting success of dryus octopefulu in front of broggerbreen polythene tents: while there was no seed-set in the control in ny-alesund. the duration of artificial warming by small greenhouses was shorter (only in the flowering period) and the degree of increased temperature was smaller in this study than in that by wookey, parsons et al. (1993). however, a higher seed-set in the short-term artificially warmed shoots indicates that tempera ture during a flowering period greatly affects seed setting success. furthermore, it suggests that temperature-dependent physiological processes such as pollen germination, pollen tube elongation, and fertilization may be strongly restricted i n a natural population of d. octopetula near brag gerbreen. therefore, it is necessary to examine pollen activity and fertilization under various temperature conditions to elucidate temperature dependent physiological traits. concluding remarks this study demonstrates that grazing on flower buds and flowers, gender variation in relation to length of growing season and flower size, and (in the flowering period) low temperature rather than pollinator limitation appear to affect strongly the seed-setting success of d. octopetuh. in this study, the warming effects on sex allocation to the female function in hermaphrodite flowers, seed viability (germinability), seedling establishment, and survi val were not examined. however, these are very important parameters to predict the population dynamics of d. octopetulu or its succession around or in front of glaciers under warmed conditions. in recent studies, wookey, robinson et al. (1995) and welker et al. (1997) reported that the phenological development of d. octoperdu is accelerated under experimentally warmed conditions. this finding corresponds with a lengthening of the growing season in autumn, greater degrees of seed-set. and a higher potential of colonization of the bare ground due to heavier seed weight and then higher germinability. for this reason. long-term studies are necessary which include manipulated experi ments and the monitoring of the growth and reproduction of many tundra plants in the field. taking into consideration both abiotic and biotic factors, such as population dynamics of insect pollinators and grazing animals, such studies would serve to clarify the changes of arctic plant populations and ecosystems under global climatic warming. acknowledgements. i am very grateful to the staff at the norwegian polar institute, kbkc and nipr for their support during my research in ny-alesund. i also thank h. kanda and g. kudo for their encouragement throughout this study, and y. bekku and t. nakatsubo for their assistance in the field work. this study was supported by a japanese ministry of education, science and culture grant-in-aid for international scientific research (no. 06044224), project “ecosystem change at the glacier-edge areas i n the arctic.” references bell, k. l. & bliss, l. c. 1980: plant reproduction in a high arctic environment. arctic a l p . res. 1 2 , 1-10, hultkn, e. 1959: studies on the genus d q ~ a s . sverisk bot. tidskr. 53, 507-547. jefferies, r. l., svoboda, j., henry, g., raillard, m. & ruess, r. 1992: tundra grazing systems and climatic change. in f. s . chapin i11 et al. (eds.): arctic ecosystems in u changing climuret an ecophysiological perspective. pp. 3 9 4 1 2 . california: academic press. kelley. j . j . & weaver, d. f. 1969: physical processes at the surface of the arctic tundra. arctic 22, 4 2 5 4 3 7 . kevan. p. g. &baker, h. g. 1983: insects as flower visitors and pollinators. annu. rev. entoni. 28, 4 0 7 4 5 3 . kjellberg, b., karlsson. s. & kerstensson, i. 1982: effects of heliotropic movements of flowers of d n a s octopetuln l. on gynoecium temperature and seed development. oecologiu 54. 10-13. klinkhamer. p. g. l. & de jong. t. j. 1993: phenotypic gender i n plants: effects of plant size and environment on allocation to seeds and tlowers i n cyiloglossum officinule. oikos 67. 81 86. kudo, g. 1991: effects of snow-free period on the phenology of alpine plants inhabiting snow patches. arct. a / p , rrs. 23. 43-43, kudo. g. 1993: size-dependent resource allocation pattern and gender variation of anetnone dehilis fish. flanr species b i d . 8, 29-34. kudo. g. 1997: sex expression and fruit set of an andromo noecious herh. feucedunum mu/tivittatwn (umbellifirde) along a snowmelt gradient. opera bot. 32. 121-128. lloyd, d. j. 1980: sexual strategies in plants. 111. a quantitative method for describing the gender in plants. n . z. j . bot. 18, 103-1 08. lovett doust, j. & lovett doust, l. 1988: sociobiology of plants: an emerging synthesis. i n j . lovett doust & l. lovett doust (eds.): plant reproductive ecology pattenis atid strategies. pp. 5-29. new york: oxford university press. mcgraw, j . b. 1985: environmental ecology of d n u s octopetulci ecotypes. 111. environmental factors and plant growth. arct. a / p . res. 17. 229-239. maxwell. b. 1992: arctic climate: potential for change under global warming. i n f. s . chapin 111 et al. (eds.): arcrir ecosptrtns it] li chaiigitig dimcite: an ecopliysiologicul prrspectice. pp. 11-34. california: academic press. wada 1999: polur research 18(2), 261-268 261 molau, u. 1993: relationships between flowering phenology and life history strategies in tundra plants. arct. alp. res. 25, 39 1-402. morishita, m. 1959: measuring of dispersion of individuals and analysis of the distributional patterns. memoir faculty of srience kyushu university series e (biology) 2, 215-235. morishita, m. 1962: 18-index. a measure of dispersion of individuals. res. l'opul. ecol. 4 , 1-7. philipp, m., bocher, j., mattsson, 0. & woodell, s. r. j. 1990: a quantitative approach to the sexual reproductive biology and population structure in some arctic flowering plant% dr)us integrifolia, silene acaulis and ranunculus nivalis. medd. grgnland, biosci. 34, 1-60. ronning, 0. 1. 1969: features of the ecology of some spitzbergen plant communities. arct. alp. res. 1, 29-44. ronning, 0. i. 1996 theflora of svalbard. pp. 66-67. oslo: norwegian polar institute. sih, a. & baltus, m.-s. 1987: patch size, pollinator behavior, and pollinator limitation in catnip. ecology 68, 1679-1690. spira, t. p. & pollack, 0. d. 1986: comparative reproductive biology of alpine biennial and perennial gentians (genriana: gentianaceae) in california. am. j . bot. 73, 3 9 4 7 . thomson, j. d., maddison, w. p. & plowright, r. c. 1982: behavior of bumble bee pollinators of aralia hispida vent. (araliaceae). oecologia 54, 326-336. totland, 0. 1994a: influence of climate, time of day and season, and flower density on insect flower visitation in alpine norway. arct. alp. res. 26, 6 c 7 1 . totland, 0. 1994b: intraseasonal variation in pollination intensity and seed-set in an alpine population of rununculus acris in southwestern norway. ecography 17, 159-165. totland, 0. 1997: effects of flowering time and temperature on growth and reproduction in leontodon uuturnnalis var. raruxaci, a late-flowering alpine plant. arcr. alp. res. 29, 285-290. wada, n., kudo, g. & kojima, s. 1999: gender variation of d n m octopetala along snowmelt and latitudinal gradients in the subarctic and the high arctic. polar biosci. 12, 87-99. welker, j. m., molau, u., parsons, a. n., robinson, c. h. & wookey, p. a. 1997: responses of d v a s ocroperala to itex environmental manipulations: a synthesis with circumpolar comparisons. global change biol. 3, 61-73. wookey, p. a,, parsons, a. n., welker, j. m., potter, j . a,, callaghan, t. v., lee, j. a. & press, m. c. 1993: comparative responses of phenology and reproductive development to simulated environmental change in sub arctic and high arctic plants. oikos 67, 490-502. wookey, p. a,, robinson, c. h., parsons, a. n., welker, j. m., press, m. c., callaghan, t. v. & lee, i. a. 1995: environmental constraints on the growth, photosynthesis and reproductive development of dryas octopetala at a high arctic polar semi-desert, svalbard. oecologia 1 0 2 , 4 7 8 4 8 9 . 268 factors affecting the seed-setting success of dryas octopetula in front of braggerbreen thermophilous molluscs on svalbard during the holocene and their paleoclimatic implications o n 0 salvigsen, steven l. forman a n d gifford h . miller salvigsen, 0.. forman, s . l. & miller, g . h. 1992: thennophilous molluscs on svalbard during the holocene and their paleoclimatic implications. polar research 11(1), 1-10. five species of guide fossils from the holocene warm period in svalbard arc considered: mytilus edulis, modiolus modiolus. arctica islandica, littorina littorea and zirphaea crispata. thcsc arc now extinct in svalbard; zirphaea crisputa, especially. requires considerable higher water temperatures than occur there today. known radiocarbon dates on mytilus, modiolus and zirphata are givcn. thirty-four dates on mytilus edulis show that it lived in svalbard from before 9500 bp to about 3500 bp, and probably again around loo0 bp. five dates on modiolus and zirphaea indicate a climatic optimum in svalbard from about 8700 bp to 7700 bp. the most favourable places then had conditions similar to the northeastern coast of finnmark. northernmost norway, today. mytilus edulis is considered a good climate indicator. and a future warming of the marine climate in svalbard could be indicated by its cventual re-immigration into thc area. otto saloigsen, norsk polurinstitutt, p . o . box 158. n-1330 oslo lufihaun, norway; steven l. forman. byrd polar research center, ohio state unioersity. i03 mendenhull laboratory. 125 south oaal mull, columbus, ohio 43210-1308. usa: gifford h. miller, center for geochronological research, i n s t a a r . unioersity of colorado, boulder. colorado 80309-0450, usa. an extensive sampling of the mollusc fauna of svalbard (fig. 1) took place during the second half of the last century (feyling-hanssen 1955 for references). molluscs (especially mytilus edulis) which are now extinct in svalbard were found in raised beach deposits, and the term “mytilus time” was introduced and discussed among geol ogists and biologists (nathorst 1884; hogbom 1913). feyling-hanssen & j ~ r s t a d (1950) and feyling hanssen (1955) described the holocene mollusc fauna of inner isfjorden in detail and also reviewed earlier observations of mollusc species in svalbard. only a few additional observations have been published since then, and feyling hanssen’s work still provides the best general view of the holocene mollusc fauna in svalbard. from the abundance of species on different levels, he divided the holocene in four climatic periods: late-glacial cold period, post-glacial temperate period, post-glacial warm period and sub-recent period. without radiocarbon dates it was only possible to obtain tentative ages for these periods. however, some dates from these zones appeared in a later publication. (feyling-hanssen & olsson 1960), semevskij (1965) and semevskij & shatov (1980) have described the mollusc fauna of raised holocene sediments in van mijenfjorden. the total number of mollusc species known from holocene deposits in svalbard is about 100. the majority are still living along the coast and in the fjords of spitsbergen. nine species, however, are now extinct here (feyling-hanssen 1955). this points to changing sea surface tem peratures during the holocene. in an archipelago like svalbard the temperature of the seawater has a decisive influence on the terrestrial climate. the former and present distribution variances of molluscs have been used in several paleoclimatic studies of arctic areas (e.g. andrews 1972; blake 1973; hjort & funder 1974; funder & weidick 1991). the species most used in variance studies have been mytilus edulis and chlarnys islandica which in greenland and the canadian arctic had a much wider distribution during the holocene climatic optimum than at present. peacock (1989) has made a thorough review of marine molluscs and their potential for environmental studies, especially emphasising arctica islandica. feyling hanssen (1955) and peacock (1989) are the key references for the discussion of problems dealt with in this paper. the purpose of this paper is to present the earlier observations together with more recent ones of some indicator species in the raised beach deposits of svalbard. the main new contribution 2 otto salvigsen, steven l . forman and gifford h . miller i 1 20 1 80 24’ 30 / svalbard \ norwegian i i \ thermophilous molluscs on svalbard 3 table 1 . radiocarbon dates on myrilus edulis, modiolus modiolus and zirphaea crirpara from svalbard. the ages are quoted as first published or as reported from the laboratory. they are corrected to a 6'ic = -25c0 pdb. either using standard values or measured values for 6i3cc. to correct for the reservoir effect, the apparent age for seawater in svalbard has been subtracted. the actual dating laboratories and authors have used slightly different standard values for 6i1c as well as for the apparent age of seawater. this causes. however, only small differences which are of no significance for the conclusions in this paper. u 126 and u 173 have not been reservoir corrected, but when placed i n fig. 2, 440 years have been subtracted. (note that in 1967 the american journal of science issued radiocarbon measuremenfs: comprehensive index, 1950-1965 with corrections for change of uppsala standard). information about corrections of the datings of samtleben (1985) is lacking. field no. zo-3 nleb 2 0 3 perl ( 2 0 2 myt sa85-28 sa78-17 sa8 1-47 3 k a f r c sa85-79 b-47 lan 83-108 sa84-36 f84-329 sa81 -80 sa84-3 1 sa87-40 s 1988-323 sa82-04 3svath kwi f84-410 sa84-34 sa82-68 sa81-48 b2 sa84-29 no 350 b a2 sa81-45 sa81-20 3dau4 b sa81-78 s1988-643 no 343 b sl84-33 s 1988-733 h-e 209-83 lab no. location (fig. 1) m a d . "c age species reference gd-1255 gd-1257 gd-1258 t-6590 dic-3076 t-3098 t-5029 gx-10038 u 173 t-5662 dic-3054 t-8385 t-4411 t-6535 t-7666 t-8333 t-4944 dic-2908 beta-11291 dic-3056 t-5214 t-5367 t-6534 lu-2137 t-6283 u-130 gd-1898 t-6591 t-6285 t-6284 t-7015 gx-10037 t-5030 t-8334 u 126 t-4628 gd-2394 kaffieyra (22) kaffieyra (22) kaffieyra (22) sarseyra (23) reinsdyrllya (25) grbhuken (26) dicksonfjorden (15) kaffieyra (22) blomstrandhalveya (24) langgrunnodden (27) kleivdalsbekken ( 5 ) erdmannflya (17) pricepynten (21) kapp ekholm (11) dicksonfjorden (14) de geerdalen (6) erdmannflya (17) derdalsbekken ( i ) kapp ekholm (10) rcindalen (3) svartfjellstranda (19) kapp wijk (13) st. jonsfjorden (20) erdmannflya (17) kapp morton (4) bromclldalen (2) dicksonfjorden (15) bohcmanflya (16) erdmannflya (17) ekholmvika (10) ebbadalen (11) dicksonfjorden (14) gbsodden (8) eidembukta (18) ebbadalen ( i i ) dicksonfjorden (14) kapp murdoch (7) mytilusbekken (9) nordfjorden (12) 6 6 6.5 0 9 8 30 7.5 4 9 13 16 3 30 7 26 6 2.3 25 17 13 1 3.5 5 10 16 5 10 8 17 15 2 18 4 5 4 7 6 3 9630 t 130 myrilus (aragonite) 9410 t 110 myrilus (calsitc) 9540 f i 10 myriius 9480 ? 100 myrilus 9375 t 80 myrilus 9360 t 110 myrilus 9220 f 120 myrilus 9195 f 270 myrilus 9180 f 100 myrilus 9070 f 190 myrilus 9030 t 100 myrilus 8970 t 110 myrilus 8955 f 90 myrilus 8930 t 70 myrilus 8820 f 120 modiolus 8730 t 170 myrilus 8670 f 90 modiolus 8620 f 120 myrilus 8610 f 120 zirphaea 8550 ? 60 myrilus 8525 t 75 myrilus 8415 t 110 myfilus' 8265 ? 80 modiolus* 8210 ? 90 myrilus 8060 2 110 myrilus 7870 ? 110 myrilus 7850 k 130 modiolus 7690 ? 80 myrilus 7680 f 90 myrilus 7595 ? 110 myrilus 7440 f 60 myfilus 7070 t 90 myfilus 6440 ? 80 myfiius 6055 t 2(k) myrilus 4780 t 90 myrilus 4690 f 100 myrilus 4200 ? 40 myrilus 3810 ? 90 mytilus 940 k 75 mytilus goslar & pazdur 1985 goslar & pazdur 1985 goslar & pazdur 1985) unpublished forman 1990b salvigsen & osterholm 1982 lauritzen et al. 1989 forman 1990a unpublished blake 1961 landvik et al. 1987 salvigsen et al. 1990 forman 1990a mangerud & svendsen unpubl. unpublished samtleben 1985 salvigsen et al. 199u unpublished mangerud & svendsen unpubl. unpublished forman 1986 forman 1990b forman 1989 salvigsen et al. 1990 salvigsen et al. 1990 elgenma & hellikscn 1986 unpublished salvigsen et al. 1990 salvigsen et al. 1990 feyling-hanssen & olsson i960 klysz et al. 1988 unpublished salvigsen 1984 forman 1990a klysz et al. 1988 unpublished mangerud & svendsen unpubl. feyling-hanssen & olsson 1960 samtleben 1985 'dating performed on another species in the same bed. is, however, the presentation of radiocarbon dates (table 1) which makes it possible t o obtain an absolute age for the holocene marine climatic optimum in svalbard. physical setting a simplified picture of the present surface cur rents in the barents sea area is shown in fig. 2. 4 otto saluigsen, steven l . forman and gifford h . miller 80' 78o 76' 74, 72' 70' 68 // -+ atlantic water -+ arctic water ...., norwegian coastal current 11 i 5' 10' 15' 20' 25" 30' 35' 40' 45' 50' 55o fig. 2. surface currents in the barents sea, modified from loeng 1985. surface temperatures in this region are controlled mainly by the varying inflow of arctic and atlan tic water. this is illustrated by an example in fig. 3 which shows the maximum sea surface temperatures during the summer of 1991. more representative measurements show that at the northernmost mainland of norway the sum mer surface temperature (sst) of atlantic water is about 10°c, and off western svalbard it is 5°c or less (gammelsr~d & rudels 1981). the sst of the inner fjords may be higher because of the atmospheric heating in sheltered areas and the small inflow of cold water, but measurements are lacking. the limited knowledge of the sea surface temperatures during the summers makes it there fore difficult to discuss present and former living conditions for the molluscs in detail. the overall sea ice conditions are given by vinje (1985), but statistics for the duration of sea ice cover in the inner fjords are not available. thermophilous molluscs on svalbard 5 fig. 3. map with sea surface temperatures modified from iskart nr. 33/91 published by the norwegian meteorological institute. ice-covered area (shaded) and temperature isolines are based on observations from ships and satellite measurements in the period august 15-19, 1991. this period showed the highest sea surface temperatures around svalbard that year. holocene distribution of thermophilous molluscs in svalbard five species of conspicuous guide fossils indi cating deposits from the holocene warm period in svalbard will be considered: mytilus edulis, arctica islandica, littorina littorea, modiolus modiolus and zirphaea crispata. these species are indicator species and can be correlated with open water summer surface temperatures (pea cock 1989). apart from mytilus they require con siderable higher water temperatures than occur around spitsbergen today. an indication of the size of the temperature demands may be afforded by peacock’s (1989) comparison of modern dis tributions along the norwegian coasts with sea surface temperatures. from this it appears that zirphaea crispata is distributed in areas with sum 6 otto salvigsen, steven l. forman and gifford h . miller mer surface temperatures above 8”c, while arc tics islandica and modiolus modiolus occur in areas with temperatures higher than 6°c in the barents sea (see also funder & weidick 1991). chlamys islandica is usually regarded as a sub arctic species, but it has recently been recorded alive from waters around the entire svalbard archipelago ( b j ~ r n gulliksen pers. comm. 1986). it occurs in raised beach deposits on sjubyane in the far north (fig. l ) , as well as o n kong karls land (salvigsen observations 1978-1980). the wide distribution of chlamys islandica in svalbard demonstrates that this archipelago had and still has warmer sst than areas at the same latitude in greenland and arctic canada (funder & weidic 1991). in contrast to what is the case in svalbard, chlamys islandica in east greenland had a much wider distribution during the holocene climatic optimum than at present (hjort & funder 1974). mytilus edulis is now extinct in svalbard waters but was widely distributed during the early hol ocene. its shells have been found on the west coast from nottinghambukta north of hornsund (dmoch 1977) to blomstrandhalv~ya in kongsfjorden. mytilus edulis is abundant throughout the isfjorden area, but not found in the inner parts of van mijenfjorden. in the north western corner of the archipelago there has been no positive shoreline displacement after 9500 bp and mytilus can thus only be expected in sub marine deposits along the shore. on the northern coast it has been recorded from raudfjorden in the west to langgrunnodden on nordaustlandet (blake 1962). it has also lived in the hin lopenstretet area. o n the eastern coast it has been reported from southwestern e d g e ~ y a and from svensk~ya, kong karls land. on e d g e ~ y a it was only found at low levels in the southwestern part of the island (knipowitsch 1903), and not in situ, hence age estimates are not possible. during the 1991 fieldwork of the european science foun dation project, “polar north atlantic margins, late ceneozoic evolution” (ponam) in eastern svalbard, several observations of mytilus were recorded from e d g e ~ y a , but it was not observed on barentscbya (different reports in landvik 1991). two small fragments from s v e n s k ~ y a have been reported from 25 m a . s. 1. (hagg 1950). in 1979 salvigsen visited the same locality but was unable t o find any traces of mytilus, nor was it found in other raised beach deposits in kong karls land. its occurrence in these islands seems therefore to have been very limited. mytilusedulis has been found in raised sediments as far east and north as in frans josef land (nansen 1902) and should therefore be expected to have occurred throughout svalbard. however, in nordaustlan det mytilus edulis has only been reported from the western area, but it should be kept in mind that the northern coast of nordaustlandet has very few reports on shell faunas. elsewhere, the summer surface temperature of the water has probably been too low for mytilus during the holocene. salvigsen looked for mytilus shells without success on sjubyane in 1978 and 1980. arctica islandica, littorina littorea, modiolus modiolus and zirphaea crispata require higher temperatures than mytilus edulis, especially zir phaea crispata (peacock 1989). however, all three species, are well known from holocene sediments in the inner isfjorden area. arctica islandica has also been reported from prim karls forland and lomfjorden. its occurrence in lomfjorden, by hinlopenstretet. is most remarkable and may indicate a former wider distribution than indi cated by the reports. littorina littorea seems to have had a similar distribution as arctica islan dica. it is found at many places in isfjorden, and in the woodfjorden area on the north coast. in addition t o finds referred to by feyling-hanssen (1955), a single find from southern spitsbergen, north of hornsund, has been made by dmoch (1977). it occurs in mytilus beds on erdmannflya in isfjorden (salvigsen et al. 1990). littorina lit torea probably had a wider distribution than hith erto reported, because it is not so conspicuous and easy to recognise in the field as the larger valves, e.g. those of arctica islandica and mytilus edrilis. modiolus modiolus had until recently only been reported from holocene sediments in inner isfjorden, but in 1984 it was found on erd mannflya in outer isfjorden, where a few frag ments occurred among mytilus edulis shells (salvigsen et al. 1990). it has also been reported from sublittortal sediments at the head of st. jonsfjorden (forman 1986). zirphaea crispata has only been reported from inner isfjorden and seems to have had the most limited distribution in svalbard of the here mentioned indicator species. dating of the thermophilous molluscs known dates on thermophilous molluscs from svalbard are listed in table 1: thirty-four dates thermophilous molluscs on svalbard 7 is lacking in the terraces of the “late-glacial cold period” and the “sub-recent period”. the most likely conclusion seems therefore to be that the climate was tolerable for mytilus edulis during a continuous period of about 6000 years. dates from the “empty” period could probably be obtained by a systematic dating of myrilus shells from inner isfjorden. the mytilus terrace of feyl ing-hanssen (1955) seems also t o be 5000 years or younger, and optimal conditions for mytilus edulis seem to have occurred between 5000 and 4000 bp in inner isfjorden. a surprising dating of mytilus from spitsbergen was presented by c. samtleben (1985 and pers. com.) who studied microstructures of mytilus shells from svalbard and other areas. shells on the present beach of nordfjorden in inner isfjorden were radiocarbon dated t o 940 f 75 years. this is the first and only mytilus date from svalbard younger than 3500 bp, and it indicates that mytilus lived in svalbard about 1000 years ago during what is called the little climatic optimum. a confirmation of this single date would be desir able, but probably difficult to obtain. the isostatic uplift during the last 1000 years has been insig nificant, and many shells on the present shore have been washed out from older sediments, e.g. on mytilus, four dates on modiolus and one on zirphaea. the original purpose for most of the dating has been either dating of old, mostly iso statically elevated shorelines, or the dating of sediments. the highest lying and oldest shells have therefore often been chosen for dating. along much of the western coast of spitsbergen it has been possible t o date only the oldest mytilus shells because younger shorelines are below present sea level (forman 1990a). but never theless, when seen together these dates give a great deal of information about the former occur rence of thermophilous molluscs in svalbard, even if they are not statistically representative for the climatic optimum. the dating results (table 1) indicate that mytilus edulis was well established in svalbard waters before 9500 bp. the distribution of ages (fig. 4) indicates its presence in svalbard until at least about 3500 bp, even though no datings from between 6500 bp (t-4628) and 4700 bp (t-5030) have been obtained. observations in the field, however, indicate that mytilus edulis lived in sval bard also during this period. feyling-hanssen (1955) shows that mytilus occurs in all terraces in the “post-glacial temperate period” and the “post-glacial warm period” in billefjorden, but it zirphaea crispata modiolus modiolus y mytilus edulis 10 9 8 7 6 5 4 3 2 1 0 radiocarbon ages (ka) fig. 4. frequency distribution of radiocarbon dated thermophilous molluscs from svalbard. 8 otto saluigsen, steven l. forman and gifford h . miller 7000 year-old shells from the surface of the mod ern beach ridge in dicksonfjorden, inner isfjor den (t-7015). arctica islandica from svalbard has not been radiocarbon dated, but the altitudes where it is found give some indications about minimum ages for its first occurrence. in billefjorden it has been found at altitudes which indicate an immigration well before 8000 bp (feyling-hanssen 1955; sal vigsen 1984). its highest reported level in lomfjorden, 21 m (kulling & ahlmann 1936), indicates that it lived there before 7500 bp. besides mytilus, arctica tlandica is the most abundant of the indicator species in dickson fjorden. nor has littorina littorea from svalbard been radiocarbon dated, but it is found on levels from 31 m to 2 m in inner isfjorden (feyling-hanssen 1955). this indicates a longlasting presence start ing before 8000 bp. dicksonfjorden probably had the most numerous occurrences in svalbard of modiolus modiolus. it was found in situ in sublittoral sedi ments in a section at kapp nathorst. the modiolus bearing layer was only about 1 m thick, indicating a relatively short presence. one valve with a weight of more than 50g yielded the radiocarbon age 8820 2 120 years bp (t-4411). a large fragment from another deposit in the inner part of the fjord, at raudkollen, had the age 7850 k 90 years bp (t-6534). it was found in a stream cut through a marine terrace, and no in situ shells were observed there. a radiocarbon date on one fragment of modiolus modiolus from erdmannflya in outer isfjorden gave the age 8670 * 130 years bp (t-6535). these three modiolus dates, combined with field observa tions, indicate that it lived in isfjorden for more than 1000 years. forman (1986, 1989) dated paired mya truncata shells from sublittoral sands in st. jonsfjorden which among other species included modiolus modiolw, mytilus edulis and littorina littorea. the age 8265 5 80 (dic-3056) indicates that the sst in the inner part of that fjord was considerably warmer before 8ooo bp than today. the only known date of the low arctic species zirphaea crispata from svalbard is on shells from kapp ekholm in billefjorden. the age was 8610 k 120 years bp (t-8333) (mangerud & svendsen unpubl.). the dates on modiolus and zirphaea lead t o the conclusion that svalbard had an early holocene marine climatic optimum with a culmination between 9000 and 7500 bp. most of the dates are close to 8600 bp, the most probable time for the maximum sst. potential for the detection of climatic changes changes of the marine climate in svalbard can be deduced from the composition of the past marine macro fauna. radiocarbon dating of new appear ances and extinctions of indicator species provides a chronology of climatic changes during the hol ocene. the molluscs dealt with here are expected to respond quickly to sst changes. they can spread to new areas as their larvae are carried by currents. small, fresh species of mytilus edulis have also been found on seaweed at spitsbergen (heintz 1926; feyling-hanssen 1955) where they probably have drifted from southern areas. the spread and the settlement of the planktonic larvae could have been assisted by northward fluc tuations of the warm atlantic water. adult mol luscs with their greater tolerance could then survive intervals with colder marine climate, and successful spawnings could take place in the most favourable summers (peacock 1989). the climatic changes can also be seen in hol ocene deposits with microand macrofossils of plants (hyvarinen 1970; gottlich & hornburg 1982; serebarannyy et al. 1984; birks 1991), but for the development of the flora there will always be a time lag compared with the actual climatic changes. the exact limiting temperatures for the indi cator species are not known, and it is therefore difficult to quantify temperatures for svalbard during the holocene. feyling-hanssen (1955, p. 33) discussed paleoclimatic evidence of the fossil fauna. he concluded that during the “post-glacial warm period” the climate was “no worse than that of the low-arctic subregion of to-day, any way, no better than that of the high-boreal”. h e also suggested that the climatic conditions were more favourable in the beginning of this period than later in the same period. the abundance of mytilus edulis on low levels in isfjorden indicates the latest slight improvement of the climate before the final decline of the warm period. samtleben (1985) observed microstructures in mytilus shells from inner isfjorden resembling those in living thermophilous molluscs on svalbard 9 mussels from northeastern norway, indicating similar climatic conditions. the microstructure of the shells shows strong seasonality with appar ently short but favourable summer periods and relatively long winter periods. samtleben also constructed a temperature curve from values of mytilus shells from isfjorden (suggesting the same salinity as that of present time summer waters in the fjord); the curve indicated summer surface temperatures up to 10°c. the mollusc faunas show that the marine cli mate in svalbard during most of the holocene was warmer than that of today. during the climatic optimum, in the most favourable places in spits bergen, it was probably similar t o the present climate on the eastern coast of finnmark, north ernmost norway. our conclusions regarding the rise in sst during the holocene are that mytilus edulis suggests a rise of about 1°c in sst and zirphaea crispata at least a 3°c rise in sst. this is in agreement with the conclusions of funder & weidick (1991) for greenland during the holo cene. funder & weidick also emphasise that the immigration of boreal molluscs to greenland was determined by oceanic rather than climatic change. birks (1991), in her studies of the veg etational history of west spitsbergen, indicates a mean july temperature for the early holocene about 2°c higher than today. it is obvious that the molluscs will play an important role i n further studies of the mid hol ocene climatic optimum in svalbard and other arctic areas. more remarkable, however, is the fact that the little climatic optimum about 1000 years ago also seems to have had favourable con ditions for mytilus edulis in inner isfjorden. molluscs in svalbard reflect warmer sst, and the mollusc fauna of western svalbard may be instrumental in detecting a possible larger supply of warm atlantic water to svalbard. molluscs respond mostly to increasing summer tempera tures. they therefore can only supply limited information about the rest of the year and the mean annual temperature. this leads to the conclusion that if a future climatic optimum develops in the arctic, it may be detected in the mollusc fauna of western sval bard if its character is analogous to the holocene climatic optimum. most greenhouse climate models show an asymmetric warming in the winter with modest or no changes during the summer (mitchell et al. 1990). the holocene climatic optimum thus seems at our present state of knowl edge to be a bad analog for greenhouse warming in the arctic. conclusions during the holocene, isfjorden had the largest occurrence in svalbard of molluscs which can be correlated with higher open water summer temperatures, indicating that this area had and still has the warmest marine climate in the archi pelago. mytilus edulis lived in svalbard from at least 9500 to 3500 bp and probably again around 1000 bp. the species which require the highest tem peratures, zirphaea crispata and modiolus modiolus, indicate optimal conditions around 8700 to 7800 bp. the distribution of thermophilous molluscs during the holocene climatic optimum is related to the present pattern of summer surface tem peratures, although temperatures then were 1 3°c higher. molluscs may immigrate t o svalbard via the warm west spitsbergen current and are therefore able to respond quickly t o climatic changes. if a global warming results in higher summer surface temperatures, mytilus edulis may soon live again along the shores of svalbard. it is considered as a reliable climate indicator and is thus useful for detection of a possible warming of the marine climate in the arctic. acknowledgements. we would like to thank jan mangerud and john inge svendsen for providing unpublished radiocarbon dates. references anderson, g . 1910: die jetzige und fossile quartarflora spits bergens als zeugnis von klimaanderungen. posfglariale kli maueranderungen, 409-417. stockholm. andrews, j. t. 1972: recent and fossil growth rates of marine bivalves, canadian arctic, and late-quaternary arctic mar ine environments. paleogeogr. paleoclimatol., paleoecol., birks, h . h. 1991: holocene vegetational history and climatic change in west spitsbergen plant macrofossils from skardtj~ma, an arctic lake. the holocene 1 , 209-218. blake, w . , jr. 1%1: radiocarbon dating of raised beaches in nordaustlandet, spitsbergen. pp. 133-145 in raasch, g . 0. (ed.): geology o f f h e arcfic. univ. of toronto press, toronto. blake, w . , jr. 1%2: geomorphology and glacial geology in nordaustlandef, spitsbergen. ph. d . thesis ohio state univ. 470 pp. 157-176. 10 otto salvigsen, steven l . forman and gifford h . miller blake, w., jr. 1973: former occurrence of mytilus edulis on coburg island, arctic archipelago. naturalkte canadian 100, dmoch, 1. 1977: characteristic of a fauna from a 4 m terrace at nottinghambukta (west spitsbergen). acta universitatis nikolai copernici (aunc). geografia 13, torun, 181-197. elgersma, a. & helliksen, d. 1986: kvartargeologiske under s@kelser i van mijenfjordomrddet, spitsbergen. cand. scient. thesis, univ. of bergen. 219 pp. + figs. feyling-hanssen. r. w. 1955: stratigraphy of the marine late pleistocene of billefjorden, vestspitsbergen. norsk polar inst. skrifer 107. 186 pp. feyling-hanssen, r. w. & jarstad, f. a. 1950: quaternary fossils from the sassen-area in isfjorden, west-spitsbergen (the marine mollusc fauna). norsk polarinst. skrifier 94. feyling-hanssen, r. w. & olsson, i. 1960: five radiocarbon datings of post glacial shorelines in central spitsbergen. norsk geogr. tidrskr. 17, 122-131. forman, s . l. 1986: quaternary glacial, marine, and soil devel opmental history of the forlandsund area, western spits bergen, svalbard. ph.d. thesis, univ. of colorado, 330 pp. forman, s. l. 1989: late weichselian glaciation and deg laciation of the forlandsundet area, western spitsbergen. boreas 18, 51-61. forman, s . l. 1990a: post-glacial relative sea-level history of northwestern spitsbergen, svalbard. geol. soc. of am. bull. 102, 1580-1590. forman. s. l. (comp.) 1990b: svalbard radiocarbon date list 1. occasional paper no. 47 instaar, boulder. 48 pp. funder, s. & weidick, a. 1991: holocene boreal molluscs in greenland paleooceanographic implications. paleogr. paleoclimatol. paleoecol85, 123-135. gammelsrad, t. & rudels, b. 1981: hydrographic and currrent measurements in the fram strait, august 1981. polar research i n . s . , 115-126. goslar, t. & pazdur, m. f. 1985: datowanie muszli mieczakow metoda i4c. kwartalnik geologiczny 29, 459-412. gottlich, k. & hornburg, p. 1982: ein zeuge warmzeitlicher moore im adventdalen auf spitsbergen. telma 12, 253 260. heintz, a. 1926: bliskjell pa spitsbergen. norsk geogr. tidrskr. 9,14-16. hjort, c. & funder, s. 1974: the subfossil occurrence of mytilus edulis l. i n central east greenland. boreas 3,23-33. hyvbrinen, h. 1970: flandrian pollen diagrams from svalbard. geogr. ann. 52a, 213-222. hi@, r. 1950: kvartara marina fossil fran spetsbergen insam lada av svenska expeditioner. geol. foren. forhandl. 72, hdgbom, b. 1913: om spetsbergens mytilustid. geol. fiiren. stockh. forh. 35, 151-156. klysz, p., lindner, l., makowska. a., marks, l. & wysok inski, l. 1988: late quaternary glacial episodes and sea level changes in the northeastern billefjord region, central spitsbergen. acta geologica polonica 38, 105-123. knipowitsch, n. 1903: 1v. mollusca und brachiopoda. (zool ogische ergebnisse der russischen expeditionen nach spits bergen. nachtrag.) extrait de i‘annuaire du musee zoologique de i‘academie des sciences de st. petersbourg. 8. kulling, 0. & ahlmann, h. w. 1936: observations on raised 51-58. 85 pp. 331-347. 11 pp. beaches and their faunas. surface markings. geogr. ann. 18, landvik, j. y., mangerud, j. & salvigsen, 0. 1987: the late weichselian and holocene shoreline displacement on the west-central coast of svalbard. polar research 5 n. s., 29-44. landvik, j . y. (ed.) 1991: fieldwork in svalbard 1991. ponam. preliminary report. 59 pp. lauritzen, o., andresen, a., salvigsen, 0. & winsnes t. s. 1989: geological map of svalbard l:lw,ooo. sheet c8g eillefjorden. map + 32 pp. text. loeng, h. 1985: ecological features of the barents sea. the 6th international conference of comitk arctique. marine living system of the far north. fairbanks. alaska. 54 pp. mitchell, j. f. b., manabe, s., meleshko, v. & tokioka, t. 1990: equilibrium climate change and its implications for the future pp. 131-172 in houghton, j. t., jenkins, g. j. & ephraums, j. j. (eds.): climate change. the lpcc scientific assessment. cambridge. nansen, f. 1902: the oceanography of the north polar basin. the norwegian north polar expedition, 18931896. scient. res. 3, christiania. nathorst, a. g. 1884: redog6relse for den tiusammans med g. de geer i r 1882 foretagna geologiska expeditionen till spetsbergen. bihang ti1 k. svenska vetensk. akad. handl. 9. stockholm. 79 pp. peacock, j. d. 1989: marine molluscs and late quaternary environmental studies with particular reference to the late glacial period in northwestern europe: a review. quaternary science reviews 8, 119-192. salvigsen, 0. 1984: occurrence of pumice on raised beaches and holocene shoreline displacement in the inner isfjorden area, svalbard. polar research 2 a s . , 107-113. salvigsen, 0. & osterholm, h. 1982: radiocarbon dated raised beaches and glacial history of the northern coast of spits bergen. polar research 1,97-115. salvigsen, 0 . elgersma, a., hjort, c., lagerlund, e., liestl, 0. & svensson, n.-0. 1990: glacial history and shoreline displacement on erdmannflya and bohemanflya, spitsber gen, svalbard. polar research 8, 261-213. samtleben, c. 1985: climatic influence on shell microstructure in mytilus edulis from spitsbergen. poster presentation on the “75. jahrestagung der geologischen vereinung”, 1985 kiel, frg. semevskij, d. v. 1965: marine terraces of van mijenfjorden and billefjorden and their palaeontological characterization. materials on the geology of spitsbergen. niiga, leningrad, 230-238. (internal translation from russian, norsk polar institutt.) semevskij, d. v. & skatov, e. p. 1980: quaternary fossil fauna of invertebrates of the archipelago of svalbard. pp. 12%133 in: geology of the sedimentary platform cover of the archipelago of svalbard. collection of scientific papers. niiga, leningrad. (internal translation from russian, norsk polarinstitutt.) serebarannyy, l. p., tishkov, a. a., malaysova, ye. s., sol omina, o.n. & ll’ves, e. 0. 1984: reconstruction of the development of vegetation in arctic high latitudes. izvestiya an ssr, seriya geografichenskaya, 6 . (translation from rus sian: polar geography and geology 9, 308-320.) vmje, t. 1985: drift, composition, morphology and distribution of the sea ice fields in the barents sea. norsk polarinst. skr. 179 c , 26 pp. + map. 1-19. breeding distribution and abundance of the great cormorant phalacrocorax carbo carbo in greenland david boertmann and anders mosbech boertmann, d. & mosbech, a. 1997: breeding distribution and abundance of the great cormorant phalacrocorax carbo carbo in greenland. polar research 16(2), 93-100. the greenland population of the great cormorant phalacrocorax carbo carbo numbers 200&3000 pairs which breed in about 110 colonies distributed along a 1000 !an long coastline in central and northern west greenland. the number of colonies has increased and the breeding range has expanded in recent decades. these trends are believed to be related to a reduced hunting pressure. the number of nests per colony is smaller than in european colonies. the population is of particular conservation concern to greenland because of its small size and presumed discrete status. david boerhnann and anclers mosbech, national environmental research institute, department of arctic environment, tagensvej 135, 4th floor, dk-2200 copenhagen n, denmark. ''~po~ar~ns''' introduction population. since the late 1970s, persecution has ~~~ the subspecies phalacrocorax carbo carbo is the north atlantic representative of the widespread and polytypic species, great cormorant p. c. carbo. the nearctic breeding range of this subspecies is restricted to maine, the gulf of st. lawrence and greenland. the palearctic breeding range is more widespread, extending in the south from northwestern france northwards to britain and ireland, norway, the kola peninsula of russia and western iceland (cramp & simmons 1977; debout et al. 1995). the taxonomic status of the small population breeding on sardinia in the mediterra nean remains unclear (j.-c. thibault, pers. comm. 1996). the great cormorant is the only cormorant occumng in greenland, and the population is the northernmost in the world. the breeding colonies are found on steep sea-facing cliffs, occasionally on low islands and along exposed coasts as well as in fiords and inshore waters. early in the twentieth century corinorant populations were severely reduced because of persecution (erskine 1972; cramp & simmons 1977); cormorants were considered pests by fishermen, eggs and birds were collected or shot for consumption, and skins were used for the manufacture of ladies' clothing (salomonsen 1950; erskine 1972). the greenland population was so heavily exploited that many breeding colonies were exterminated. local authors (ber telsen 1921; oldenow 1933, 1935) expressed grave concern for the future of the greenland _ _ in general ceased throughout &atlantic range and many populations have increased (debout et al. 1995). currently, cormorants are mainly breeding along the coasts of central and northern west greenland between 65'30" and 74"n. before and at the turn of the century cormorants bred in southern west greenland as well, although in small numbers (salomonsen 1950). according to helms (1926) only one colony was recorded in the tasiilaq district in southeast greenland, and it was abandoned before 1900. this paper presents results from seabird studies conducted from 1992 to 1996 by the national environmental research institute, department of arctic environment (neri-ae). these studies were initiated in response to increasing offshore hydrocarbon exploration in the davis strait and baffin bay. based on these studies, this paper summarises the present distribution and popula tion size of the greenland great cormorant, with reference to the other north atlantic populations. study area west greenland (fig. 1) is one of three admin istrative regions of greenland. ninety-three per cent of the human population (total population about 55,000) live in this area. the climate is low arctic except for the high arctic northernmost part. the waters off the outer coast from sisimiut district and southwards usually do not freeze during winter. 94 d. boertmann fig. 1. west and southeast greenland, with major localities and areas mentioned in text. the framed areas (upernavik, qeqertarsuaq, nassuttooq, and maniitsoq and nuuk) are enlarged in figs. 2-5. the legend applies to figs. 2-5. methods neri-ae maintains a greenland seabird colony database, which was compiled in collaboration with ornis consult ltd. this database currently contains information on 1232 greenland seabird colonies and includes historical as well as up-to date information (boertmann et al. 1996). the database includes 288 records of great cormorant colonies: 128 (44%) are from the unpublished field notes (1946-1980) of the danish ornithologist finn salomonsen, 93 records (32%) are from our own (neri-ae) surveys, 25 (9%) from the data collected during the “greenland guillemot project” in the 1980s fig. 2. the distribution and size of great cormorant colonies in the upernavik area. see fig. 1 for legend. colonies not visited since 1975 are indicated with unknown numbers. major towns are indicated with an asterisk. (kampp et al. 1994), 14 (5%) from the surveys of joensen & preuss (1972) in upernavik district during 1965, 13 ( 5 % ) from surveys on disko island in 1990-1992 carried out by ole frimer (unpubl. data) and 15 (5%) were supplied by other observers. other researchers (a. 0. f. wille pers. c o r n . 1995) have surveyed the fiords and outer coasts of nuuk, paamiut and qaqortoq districts without finding breeding cormorants. the most recent information on great cormor ant colonies is based on surveys carried out from a small ship by the authors in the summers of 1992 and 1994. as many as possible of the previously known seabird colonies were investigated and new colonies were searched for. in 1992, the outer coast from aasiaat to northern paamiut was surveyed between 22 june and 20 july; in 1994, the coast between ilulissat and upernavik was surveyed between 28 june and 20 july (fig. 1). breeding distribution and abundance of the great cormorant 95 fig. 3. the distribution and size of great cormorant colonies in the qeqertarsuaq area (disko island, small islands to the north and south of disko island and nuussuaq) and the disko bugt area (the eastern coast). see legend on fig. 1 and caption to fig. 2. fig. 5 . the distribution and size of great cormorant colonies in the maniitsoq and nuuk areas. see legend on fig. 1 and caption to fig. 2. fig. 4 . the distribution and size of great cormorant colonies in the nassuttooq area. see legend on fig. 1 and caption to fig. 2. the other surveys mentioned above were carried out from mid-june to early august with the majority in july. supplementary information on great cormorant colonies was gathered during our aerial surveys for moulting ducks in the coastal waters of west greenland during late august and early septem ber in 1993. 1994 and 1995. however, it was often difficult to differentiate colonies from resting sites this late in the season. in summary, almost all west greenland coasts have been searched for seabird colonies during the recent two decades. there are, however, a few significant gaps, such as the large afersiorfik fiord, which has not been surveyed since 1954, and the interior parts of uummannaq and upernavik districts. the colonies in greenland, even the small ones, are very easy to locate due to the significant white guano staining and the conspicuous nests. a breeding colony is here defined as an association of cormorant pairs breeding on the same topo graphical feature, such as a cliff or a small island. breeding numbers are presented as “apparently occupied nests” (aons), which are nests with chicks or attending adults. as great cormorant nests are easy to count, we assume that the historical accounts of the colonies equate appar ently occupied nests (aons). due to the skewed frequency distribution of aons among the colonies (fig. 6), the median 96 d. boertmann table 1 . summary of great cormorant colonies in west greenland 19761995 no. of colonies not additional new colonies colonies other active surveyed later probable recorded abandoned area surveyed no. of aons colonies* than 1975 colonies since 1986** colonies upernavik disko bay qeqertarsuaq n as s u tt o oq maniitsoq nuuk total qaqortoq 16 15 14 18 11 1 0 75 143 399 301 672 157 8 0 1672 14 13 9 3 0 0 1 40 0 i*** 2 2 2 0 0 7 * nests not counted ** included in fust column *** before 1960 fig. 6. frequency distribution of size of greenland great cormorant colonies. colonies colonies were surveyed more than once, the most recent figure is given. v ) o m o v ) o v ) 8 ’ + 2 2 2 $3 2 7 3 2 3 9 5 5 3 2 2 2 s = 5 5 i? i? 5 surveyed 19761995. if v) o v) o v) o 10 o v) o v) o v, o 10 ej ej wj wj 3 v) v) \o w (5 e 00 oo ;h” 4 2 2 4 111111111+ no. of apparently occupied nests number of aons is used for estimating the total number of aons in colonies with unknown numbers. differences among median numbers of aons in the cormorant areas were tested using resampling simulation (simon 1995). the areas were com pared in pairs. the simulated difference in medians between two areas was calculated by selecting at random with replacement from the combined number of aons of the two areas. this procedure was repeated 1000 times to obtain the bootstrapped distribution. the likelihood (p) of the observed difference in medians is calculated from this distribution. results distribution and abundance presently 110 great cormorant colony sites are known in west greenland, abandoned colonies included (table 1). the colonies are distributed breeding distribution and abundance of the great cormorant 97 t y n .i .s zf 4 fig. 7. median number of nests per colony in the five areas with great cormorant colonies. based on survey results 1976-1995. error bars indicate 95% bootstrap (lo00 times) confidence intervals (simon 1995). statistically significant differences in median number of nests per colony are found only between upernavik and nassuttooq (resampling simula tion (see methods section), p = 0.009). aons = apparently occupied nests. among five areas: upernavik (fig. 2 ) , qeqertar suaq (disko island, adjacent islands and nuussuaq peninsula) (fig. 3), disko bugt (fig. 3), nassut tooq (fig. 4) and maniitsoq (fig. 5). a single colony is located in the nuuk area (fig. 5). there are counts from 75 colonies in the period 1976-1995, an additional 17 colonies were recorded as being active, but nests were not counted. moreover, during aircraft surveys 40 probable breeding colonies have been observed (table 1). the great cormorant colonies in greenland are small (fig. 6). the 75 colonies surveyed over the past 20 years range from 1 to 138 aons, the average size being 22.4 aons, and the median size 15 aons. the variation in median numbers among the five cormorant areas is presented in fig. 7. population trends among the new colonies found by the authors in upernavik district in 1994, six were located on coasts, previously surveyed in 1965 (joensen & preuss 1972). four of these six colonies were found north of the previous range. however, great 9 upernavik 1%5-1994, n= 10 0 upernavik 1%5-1983, n = 3 a disk0 bugt 1946-1975, n = 5 0 disko bugt 1975-1980, n = 5 x nassutt~oq 1954-1980, n = 15 0 maniitsoq 1977-1990. n = 9 i ' % i " " i 1 10 100 no. of aons + 1 per colony year 1 fig. 8. log-log plot of sizes of colonies counted twice during surveys in different years (1 has been added to all results to include 0 counts). colonies in the upper left part had increased and those in the lower right part decreased between counts. included are areas with three or more colonies surveyed both years. aons = apparently occupied nests. cormorants were reported breeding in this part of upernavik district in the late 1800s (salomonsen 1950). new colonies in the northern part of the qeqertarsuaq population are probably also the result of a northward range expansion. this area apparently lacked colonies before 1989 (salo monsen 1974a, 1979b; bennike 1990). southward range expansion has also occurred, with a colony in the nuuk district having been re established. this colony is situated about 150 km to the south of the nearest colonies in the maniitsoq area. a few cormorants nested in this colony until 1928 and perhaps also as late as 1936 (nicholson 1930; oldenow 1935; salomonsen 1950). no cormorants were present in 1974, but eight pairs nested in 1986 (boertmann et al. 98 d. boertmann 1996). another indication of a southwards range extension is the observation of two adults in company with two newly fledged juveniles in an archipelago in qaqortoq district in 1992, 600 km south of the maniitsoq colonies. these birds may have been local breeders, but conclusive evidence was lacking (kampp & falk 1994). changes in numbers of aons in colonies in areas surveyed twice are shown in fig. 8, which includes 10 colonies established and 3 abandoned between surveys. although more colonies in this sample have increased (23) than decreased (20) and the total number of aons increased from 1007 to 1118, this trend is not statistically significant (wilcoxon matched-pairs signed-rank test, p > 0.05). population numbers the most recent surveys of active colonies (1976-1995) amounts to a total of 1672 aons. another 17 colonies were recorded active in the period. these colonies may contribute 255 aons if they have the same median number of aons as the sample of surveyed colonies (15 aons). if the colonies not surveyed after 1975 (n = 11) are still active, they may contribute a further 165 aons. moreover, the 40 colonies mainly recorded from aircraft without certain breeding evidence may contribute with a maximum of 600 aons (same median numbers as above), but perhaps much fewer as the general impression was that they were small with less than 10 pairs. this totals 2692 aons, and a conservative estimate of the current populatiori in greenland would therefore fall in the range of 2000-3000 pairs. discussion the greenland population the estimate of 2000-3000 pairs in west green land is crude, mainly because the data are derived from several surveys in different areas and over a 20-year period. the considerable between-year variation in aons within colonies can be another source of error. this can be exemplified by five colonies counted in 1975 and again in 1976: three colonies increased by 6, 19 and 33%, while two decreased by 17 and 20%. this error may to a some degree be counterbalanced by fact that the surveys are distributed over 20 years. the timing of the breeding season compared to the survey period may in some years contribute to the source of errors. the majority of the surveys were carried out in july, which is appropriate as chicks usually hatch in july (salomonsen 1967). however, in early breeding years, such as 1994 when chicks hatched in late may in ilulissat and upernavik (author’s observation), surveys tend to under estimate the aons because some nests may have failed or have fledged young when colonies were visited. finally, the population estimate is based on the assumption that all the colonies surveyed during the period 1976-1995 are still active. the oldest colonies recorded in the database have been known for more than 50 years. however, there is a natural turnover in colonies, which is difficult to quantify. this turnover probably will not influ ence the total number of breeding pairs, but may imply that some colonies were not recorded in the surveys. such colonies seem to be small, because the seven colonies known to have been abandoned in greenland were in the range of 1-30 aons (average 12 aons, median 8 aons). the greenland great cormorant population in the mid-1980s was estimated at 750-1500 pairs (evans 1984) and at 1000-2500 pairs in the late 1980s (boertmann 1994). however, these num bers should not be used as evidence of an increase in population size over the last decade, as they were based on much more fragmentary informa tion than presented in this paper. the sizes of greenland colonies (fig. 2) with an average of 22.4 aons per colony are considerably smaller than those reported for three sample areas in norway (31-179 aons, r@v & strann 1987) and one in iceland (70 aons, petersen & ingvarsson 1995). the global population of subspecies p . p . carbo debout et al. (1995) present data on sizes and trends for all national populations of great cormorant subspecies p . p . carbo. however, more recent information on some of the populations has appeared. in iceland, where great cormorants breed only in the western part of the island, the total population has recently (1995) been esti mated at 2200 pairs and it seems presently to be declining (a. petersen, pers. c o r n . ) . the cana dian population is found along the coast of the gulf of st. lawrence and on the southern part of newfoundland. the most recent account of the breeding distribution and abundance of the great cormorant 99 seabirds of atlantic canada gives an estimate of about 6300 pairs of great cormorants (lock et al. 1994). there are local estimates of 5300 pairs in nova scotia and on prince edward island (information from 1986-1990, erskine 1992), 3700 pairs in nova scotia in 1992 (milton et al. 1995), about 1000 pairs in quebec in 1990 (brousseau 1995) and at least 100 pairs on newfoundland during the 1980s (lock et al. 1994). the recently (in 1983) established popula tion in maine, usa, numbers about 200 pairs (265 in 1992 and 165 in 1995 j. drury, pers. comm. 1996). the size of the russian population breeding on the kola peninsula recently num bered 1281 pairs in 14 colonies (t. paneva & j . krasnov, pers. comm. 1996 communicated via v. bakken). the population on the faroe islands was exterminated during the middle of this century, and a recovery has not occurred, although the species is a winter visitor to the islands (salo monsen 1963; bloch & serensen 1984; s . sprrensen, pers. comm. 1996). the insular popula tion of the western mediterranean (sardinia) numbers about 45 pairs (grussu 1993, but this population may not belong to the subspecies p . c. carbo. if all these national population figures are added (norway, britain, ireland and france contribute with 37,300 pairs (debout et al. 1995)), the current total breeding numbers of subspecies p . c. carbo approximates 50,000 pairs, of which the greenland population may account for 4 4 % . protection and threats in greenland currently the great cormorant in greenland is protected from hunting from 1 april to 30 september, ten weeks more than most other seabirds (1 june-15 august). this extended protection period was adopted because the population was small and declining when the hunting regulations were revised in 1971 and because great cormorants are easy to shoot during winter (salomonsen 1974b). we have made inquiries about cormorant hunting with local residents in the districts of paamiut, nuuk, sisimiut, ilulissat and upernavik. these people agreed that today great cormorants were hunted on a very limited scale in greenland. great cormorants are rarely and only in small numbers offered for sale at the local markets for hunting products. for example, only 13 were offered for sale in nuuk during the winter 1988/89 when thousands of eiders somateria mollissima and s . spectabilis and briinnich’s guillemots uria lomvia were sold (falk & kampp 1992). indirect evidence indicates that at present the hunting pressure on the great cormorant is low. many nests are situated close to sea level where birds could easily be shot. when colonies are ap proached by boat, many adults remain on their nests or on the breeding ledges. this contrasts with the descriptions of cormorant behaviour observed by salomonsen (1950, 1967), who stated that the birds placed their nests as high as possible on the cliffs beyond the range of a shotgun, and that they were extremely shy, leaving the colonies when a boat approached. the greenland great cormorants stay within west greenland during the winter. they move gradually southwards or out from the fiords to the open water areas south of disko bugt (salomon sen 1967). of 1500 great cormorants ringed in greenland, all recoveries (267 until 1979) have been from west greenland waters (salomonsen 1979a). moreover, no birds ringed abroad have been recovered in greenland. thus the available evidence suggests that the greenland population is isolated from the other north atlantic great cormorant populations, of which the nearest are found in iceland and the gulf of st. lawrence, eastern canada. there are no current threats to the greenland cormorant population as long as hunting pressure does not increase. oil spills will be a potential threat if offshore exploration and exploitation activities are commenced. an oil spill during the breeding season would probably only affect a small proportion of the population because the birds are dispersed along an extensive coastline. moreover, the birds breeding in the fiords far from the outer coast are protected, because an off-shore oil spill will not extend far into the fiords. however, during winter a significant proportion of the population is concentrated along the outer coast, and consequently it would be more exposed to oil spills. because of its small size and presumed discrete status, the great cormorant population is of particular conservation concern to greenland. acknowledgements. several researchers have given us the opportunity to use unpublished information on local great cormorant populations: a. petersen, n. rov, j. drury, v. bakken, j.-c. thibault and particularly p. brousseau, who provided us with valuable information from canada. thanks 100 d. boertrnann also to d. carss, d. christie, s. bartle, r. barrett, m. gavrilo and l. skrynnikova who responded to our cormorant requests on the seabird listserver “seabird@uct.ac.za” on the internet, to a. fox who gave valuable comments to an early draft, to t. bregnballe, a. s. frich, b. knudsen, p. grossmann and f. wille who contributed in various ways, to f. riget for help with the statistics, to lene smith for help with the english and finally to two anonymous referees who gave valuable criticism and comments. the 1992 and 1994 surveys were financed by the greenland environmental research institute (which became neri-ae in 1996). references bennike, 0. 1990: observations of geese and other birds in west greenland, 1989 and 1990. dansk om. foren. tidsskr. 84, 145-150. bertelsen, a. 1921: fuglene i u m h a q distrikt. me&. gr@nl. 62(2), 139-214. bloch, d. & serensen, s. 1984: checklist of faroese birds. foroya skulab6kagrunnur. thorshavn, faroe islands. boertmann, d. 1994 an annotated checklist to the birds of greenland. me&. grgrrl. biosci. 38. boertmann, d., mosbech, a., falk, k. & kampp, k. 1996: seabird colonies in western greenland. national environ mental research institute, technical report 170. brousseau, p. 1995: grand cormoran. pp. 228-231 in gauthier, j. & aubry, y. (eds.): les oiseaux nicheurs du que‘bec: atlas des oiseaux du qupbec me‘ridional. association qucbccoise de groupes d’omithologues, socict6 qucbtcoise de protection de oiseaux, service canadien de la faune, environment canada, region du qubbec, montrbal. cramp, s. & simmons, k. e. l. (eds.) 1977: the birds of the westem palearctrc. vol. 1. oxford university press, oxford. debout, g., rev, n. & sellers, r. m. 1995: status and population development of cormorants phalacrocorax carbo carbo breeding on the atlantic coast of europe. ardeu 83, 47-59. erskine, a. j. 1972: the great cormorants of eastern canada. can. wildlife serv. occ. pap. no. 14. erskine, a. j. 1992 atlas of breeding birds of the maritime provinces. nimbus publishing, halifax. evans, p. g. h. 1984: the seabirds of greenland: their status and conservation. pp. 49-84 in croxall, j . p., evans, p. g. h. & schreiber, r. w. (eds.): status and conservation of the world’s seabirds. international council for bird preserva tion. technical publication no. 2. cambridge. falk, k. & kampp, k. 1992: havfugle ved vestgr#nland en opdateret oversigt. ornis consult and greenland environ mental research institute, copenhagen. grussu, m. 1995: status, distribuzione e popolazione degli uccelli nidificanti in sardegna (italia) al 1995 (prima parte). gli uccelli d’ltalia 20, 77-85. helms, 0. 1926: the birds of angmagssalik. medd. gr@nl. 58, 205-274. joensen, a. h. & preuss, n. 0. 1972: repoa on the ornithological expedition to northwest greenland 1965. medd. grqnl. 191, 5 . kampp, k. & falk, k. 1994: the birds of ydre kitsissut (kitsissut avalliit), southwest greenland. me&. grgnl. biosci. 42. kampp, k., nettleship, d. n. & evans, p. g. h. 1994: thick billed murres of greenland: status and prospects. pp. 133-154 in nettleship, d. n., burger, 1. & gochfeld, m. (eds.): seabirds on islands, threats, case studies and action plans. birdlife international, conservation series no. i . cambridge. lock, a. r., brown, r. g. b. & geniets, s. h. 1994 gazetteer of marine birds in atlantic canada, an atlas of sea bird vulnerability to oil pollution. canadian wildlife service. milton, g. r., austin-smith, p. j. & farmer, g. j. 1995: shouting at shags: a case study of cormorant management in nova scotia. colonial waterbirds 18 (special publ. i ) . 91-98. nicholson, e. m. 1930 field-notes on greenland birds. part ii. ibis (12th series) 6, 395428. oldenow, k. 1933: fugleliv i grenland. det grgnl. selsk. aarsskr. 1932-33, 17-224. oldenow, k. 1935: natutfredning i gr@nland. det grenlandske selsk. skr. ix. copenhagen, denmark. petersen, e & ingvarsson, s. 1995: the number of breeding cormorants and shags in faxafl6i bay. bliki 15, 1620. (in icelandic, with english summary). r@v, n. & strann, k.-b. 1987: the present status, breeding distribution, and colony size of the cormorant phalucrocor ax carbo carbo in norway. fauna now. ser. c . cinclus 10, 3 9 4 4 . salomonsen, f. 1950 gr@nlands fugle/the birds of green land. munksgaard, copenhagen, denmark. salomonsen, f. 1963: systematisk oversigt over nordensfugle. e. munksgaard, kflbenhavn, denmark. salomonsen, f. 1967: fuglene p m gr@nland. rhodos, kflben havn, denmark. salomonsen, f. 1974a: fuglene i menneskenes landftingmissat kalitdlit-nunine. det gr@nlandske forlag, nuuk. gr@nland. salomonsen, f. 1974b: forslag ti1 vedtaegt om jagt p i fuglene i gronland. tidsskr. grmnl. 1974/5, 155-173. salomonsen, f. 1979a: thirteenth preliminary list of recoveries abroad of birds ringed in greenland. dansk om. foren. tidsskr. 73, 191-206. (in danish, with english summary). salomonsen, f. 1979b: marine birds in the danish monarchy and their conservation. pp. 267-287 in bartonek, j. c. & nettleship, d. n. (eds.): conservation of marine birds of northem north america. united states department of the interior. fish and wildlife service. wildlife research report 1 1 . simon, j. l. 1995. resampling; fhe new statisfics. resampling stats, inc., arlington. no job name foraminiferal morphogroups in dysoxic shelf deposits from the jurassic of spitsbergen jenö nagy,1 matías reolid2 & francisco j. rodríguez-tovar3 1 department of geosciences, university of oslo, p.o. box 1047, blindern, no-0316 oslo, norway 2 departamento de geología, campus las lagunillas, universidad de jaén, es-23071 jaén, spain 3 departamento de estratigrafía y paleontología, universidad de granada, avenida fuentenueva, es-18071 granada, spainpor_112 214..221 abstract analysis of benthic foraminiferal assemblages was performed in bathonian to kimmeridgian deposits through a section covering the lower half of the agardhfjellet formation in central spitsbergen. the section consists mainly of organic-rich shales, which contain low-diversity agglutinated assemblages. in this foraminiferal succession five morphogroups were differentiated according to shell architecture (general shape, mode of coiling and number of chambers), integrated with the supposed microhabitat (epifaunal, shallow infaunal and deep infaunal) and feeding strategy (suspension-feeder, herbivore, bacterivore, etc.). the environmental evolution of the analysed section is interpreted by using the stratigraphic distribution of morphogroups, combined with species diversities and sedimentary data, in a sequence stratigraphic framework. the section comprises two depositional sequences, which demonstrate that species diversity and relative frequency of morphogroups are correlative with transgressive–regressive trends controlling depth and oxygenation of the water column. in both sequences, the maximum flooding interval is characterized by increased organic carbon content, dominance of the epifaunal morphogroups and reduced species diversity: features reflecting the increased degree of stagnation separating the transgressive phase from the regressive phase. keywords foraminifera; jurassic; morphogroups; microhabitats; palaeoenvironments; spitsbergen. correspondence jenö nagy, department of geosciences, university of oslo, p.o. box 1047, blindern, no-0316 oslo, norway. e-mail: jeno.nagy@geo.uio.no doi:10.1111/j.1751-8369.2009.00112.x as an approach to palaeoenvironmental assessment, benthic foraminiferal morphogroup analysis has attracted special attention over the last two decades. following initial papers focused on the palaeoecological significance of foraminiferal morphology (chamney 1976; severin 1983), the morphogroup concept was introduced by jones & charnock (1985). the concept was further developed in subsequent studies, and has been applied to interpret various aspects of the palaeoenvironment, such as food supply, oxygenation, substrate and salinity (nagy 1992; tyszka 1994; bąk 2004; szydlo 2004; reolid et al. 2008; among others). the morphogroup approach in this paper is applied to a foraminiferal succession formed in mainly dysoxic environments, in order to recognize changing depositional conditions in a sequence stratigraphic framework. the analysed deposits jurassic shelf environments characterized by changing oxygen levels are well represented in the agardhfjellet formation, which is extensively exposed in the central basin of spitsbergen (dypvik et al. 1991). this study deals with the lower 108 m of the agardhfjellet formation, comprising bathonian, callovian, oxfordian and kimmeridgian deposits, which have been logged and sampled from the janusfjellet section, located in central spitsbergen (figs. 1, 2). the lower part of the analysed interval corresponds to the oppdalen member, which begins with the brentskardhaugen bed, a transgressive conglomerate containing phosphatic pebbles. this is overlain by the marhøgda bed, consisting of ooids in a sandy matrix. the polar research 28 2009 214–221 © 2009 the authors214 mailto:nagy@geo.uio.no succeeding main body of the member reveals a finingupward development from fine sand and silt to shale. the lardyfjellet member consists mainly of finely laminated black shales with extremely high organic carbon content. these beds are overlain by the oppdalssåta member, which consists of dark silty shales interbedded with thin horizons of fine-grained, highly bioturbated sandstones. the upper part of the analysed section corresponds to the lower half of the slottsmøya member, consisting of laminated dark shales and grey silty shales. materials and methods the succession studied preserves an essentially continuous benthic foraminiferal record, from which approximately 6700 specimens have been counted, in samples taken from 31 levels. most of the samples were collected from well-indurated black shales that characterize the main body of the agardhfjellet formation. a smaller number of samples were taken from siltstones and fine-grained sandstones from the basal part of the formation. in the laboratory, the rock samples were disintegrated using the kerosene method described by nagy et al. (1988). the most critical phase of the procedure is the sediment disintegration, which involves soaking the sediment in kerosene, followed by boiling the partly disintegrated sample in sodium hydroxide. a large number of shale samples required between one and three repetitions of this step of the procedure (combined with hydrogen peroxide) to obtain an adequate degree of disintegration. morphogroups and subgroups a detailed analysis of the studied succession revealed a high abundance of agglutinated foraminifera, and the almost total absence of calcareous benthic specimens. in total, 35 agglutinated and two calcareous species have been observed. calcareous forms occur in very few samples, where they compose <1% of the assemblage. in the foraminiferal succession, five morphogroups are distinguished and are designated alphabetically from a to e (fig. 3; appendix). two of these groups, c and d, are further subdivided into three and two subgroups, respectively. the differentiation of morphological categories is based on three types of criteria: (1) test morphology, comprising general outline, number of chambers, chamber arrangement and architecture; (2) life habitat, characterized as deep infaunal, shallow infaunal or epifaunal; and (3) supposed feeding strategies, characterized as suspension feeders, deposit feeders, herbivores or bacterial scavengers. a useful basis for the assignment of jurassic genera to morphological categories and their environmental interpretation has accumulated as a result of several studies: nagy (1992), tyszka (1994), nagy et al. (1995) and reolid et al. (2008). a morphogroup system developed for a given sedimentary succession is often cumbersome to apply directly to a new sedimentary succession, owing to major differences in the composition of assemblages, which are mainly determined by divergences in ecosedimentary conditions, and, commonly, differencences in stratigraphic age. this is also the case with the agglutinated foraminiferal succession of the jurassic of spitsbergen, which required the development of a modified morphogroup system suitable for the analysis of assemblages adapted to hypoxic marine shelf environments. the typical species of the svalbard morphogroups are illustrated in fig. 4. in addition, illustrations of common species occurring in the section analysed are illustrated in nagy & basov (1998). fig. 1 location map of spitsbergen, svalbard, showing the position of the studied section at janusfjellet. foraminifera of dysoxic shelf deposits, spitsbergenj. nagy et al. polar research 28 2009 214–221 © 2009 the authors 215 morphogroup a this morphogroup comprises species with tubular and unilocular shells. an epifaunal habitat and suspensivorous feeding strategies are supposed. the group is represented only by rhizammina (fig. 4a), and is equivalent to subgroup 1-a of nagy (1992) and morphogroup a-1 of tyszka (1994). morphogroup b this category is represented by unilocular shells of spheric and subspheric shape. the organisms are interpreted as epifaunal, passive deposit feeders (fig. 3), among which thuramminoides is the representative genus (fig. 4b). the morphogroup is equivalent to subgroup 2-a of nagy (1992). morphogroup c this morphogroup comprises species with elongated, subcylindric, multilocular shells, adapted to infaunal life habitats (fig. 3). three subgroups have been differentiated within the group. subgroup c1 consists of uniserial forms living as shallow to deep infaunal detritivorous bacterial scavengers. reopax is the representative genus of this subgroup (fig. 4c), which is equivalent to subgroup 3-b of nagy (1992) and morphogroup a-8 of tyszka (1994). subgroup c2 is composed of species having a planispiral or streptospiral initial stage, changing to a uniserial final stage. a shallow infaunal habitat and a detritivorous bacterial scavenger feeding strategy are inferred. two genera, ammobaculites (fig. 4d) and bulbobaculites, are registered in this subgroup. the subgroup corresponds to subgroup 3-b of nagy (1992) and morphogroup a-6 of tyszka (1994). subgroup c3 consists of biserial, triserial and elongated trochospiral forms, adapted to shallow to deep infaunal habitats, with detritivorous bacterial scavenger feeding strategies. the genera included here are eomarsonella, dorothia, verneuilina and verneuilinoides (fig. 4e). the subgroup correlates to subgroup 3-b of nagy (1992) and morphogroup a-8 of tyszka (1994). morphogroup d this morphogroup includes species with spiral multilocular shells and epifaunal to shallow infaunal habitats, combined with herbivorous and detritivorous feeding strategies. two subgroups are differentiated. subgroup d1 includes globular and plano-convex forms, with trochospiral coiling. epifaunal herbivorous, detritivorous and active omnivorous feeding habits are interpreted. the registered genera are ammoglobigerina and trochammina (fig. 4f). the subgroup is equivalent to subgroup 2-b of nagy (1992) and morphogroup a-4 of tyszka (1994). subgroup d2 is typified by rounded, planispiral morphotypes, adapted to epifaunal and potentially shallow infaunal habitats, with herbivorous, detritivorous and active bacterivorous behaviour. it is represented by the fig. 2 outline of the stratigraphy, lithology and environments of the bathonian to kimmeridgian part of the agardhfjellet formation in the janusfjellet section, central spitsbergen. (lithological column redrawn and modified from århus 1998.) foraminifera of dysoxic shelf deposits, spitsbergen j. nagy et al. polar research 28 2009 214–221 © 2009 the authors216 fig. 3 morphogroups (and subgroups) differentiated in the jurassic foraminiferal succession of the janusfjellet section, with the interpreted life positions indicated. fig. 4 species exemplifying the foraminiferal morphogroups recognized in the janusfjellet section: (a) rhizammina sp., morphogroup a; (b) thuramminoides sp., morphogroup b; (c) reophax sterkii, subgroup c1; (d) ammobaculites areniferus, subgroup c2; (e) verneuilinoides aff. graciosus, subgroup c3; (f) trochammina praerosacea, subgroup d1; (g) recurvoides scherkalyensis, subgroup d2; (h) ammodiscus sp., morphogroup e. scale bars: 250 mm. foraminifera of dysoxic shelf deposits, spitsbergenj. nagy et al. polar research 28 2009 214–221 © 2009 the authors 217 genera haplophragmoides, cribrostomoides and recurvoides (fig. 4g). this category correlates with subgroup 3-a of nagy (1992) and morphogroup a-6 of tyszka (1994). morphogroup e this category includes flattened tests composed of two chambers (proloculus and second chamber), with planispiral or irregular coiling. an epifaunal to phytal lifestyle with herbivorous and detritivorous trophic strategies are interpreted. the genera glomospira, arenoturrispirillina and ammodiscus (fig. 4h) have been recognized. the morphogroup is equivalent to subgroup 4-a of nagy (1992) and morphogroup a-3 of tyszka (1994). morphogroups of calcareous taxa the extremely rare calcareous faunal component comprising lingulina and lenticulina represent flattened multilocular morphotypes, with a potentially deep infaunal microhabitat, and depositivorous and grazing omnivorous trophic behaviours. tyszka (1994) include these forms in morphogroups c-6 (lingulina) and c-8 (lenticulina). morphogroup trends in a transgressive–regressive framework the base of the studied section is an erosional unconformity cutting the underlying knorringfjellet formation. this ravinement surface represents a sequence boundary, which became flooded by the regional bathonian transgression. during the advancing transgression, a principally fining-upward succession was formed, reflecting the deepening upward depositional environment of the oppdalen member (fig. 2). it starts with the brentskardhaugen bed, a beach conglomerate containing reworked phosphatic pebbles, followed by the sandy oolites of the marhøgda bed, which is succeeded by a fine sand to shale succession, forming the rest of the member. no foraminifera were found in the lower, coarser part of the section (fig. 5). above this level, the number of species is relatively low, suggesting the effect of a restricting factor, possibly reduced salinity in surficial waters. the development of low salinity in the upper part of the water column can be explained by large freshwater discharge to the basin from the extensive adjacent land areas. the effect of this factor decreases upwards in the oppdalen member, as shown by the increasing species diversity. in the upper part of the member, there is a diversity reduction owing to decreasing oxygen levels, as evidenced by the increasing quantities of organic carbon. the oxygen-depleted conditions in deeper water could be attributed to the density-stratified nature of the water column. the foraminiferal assemblages are dominated by the digging infaunal component (morphogroup c), followed by the epifaunal group (mainly b and d1). the deep-digging group is associated with low organic carbon content, which is mainly found in the middle part of the member. the fining-upward succession of the oppdalen member terminates in the organic-rich black shale interval of the lardyfjellet member. these shales are finely laminated, papery in consistency and show high values of organic carbon (5.0–11.2%). the foraminiferal assemblages reveal minimum values of diversity and a high dominance of the epifaunal morphogroups b and d1. the shallow infaunal component (groups c2 and d2) is strongly reduced, suggesting that the redox boundary was located close to the sediment–water interface, and that there was an absence of oxygen in the typical infaunal microhabitats. these features indicate dysaerobic to anaerobic bottom water conditions, which are most pronounced in this interval within the agardhfjellet formation. the high degree of stagnation is apparently related to the maximum flooding interval (fig. 5). the oppdalssåta member of dark silty shales and interbedded fine-grained sandstones shows a generally coarsening-upward trend, reflecting the shallowing of the depositional area during the regressive phase of the first subordinate sequence of the agardhfjellet formation. the oppdalssåta member sandstones were deposited as offshore bars (dypvik et al. 1991), and their extremely high degree of bioturbation is in accordance with deposition under oxic conditions. the shales between the sandbars were deposited under dysaerobic conditions, however, as shown by their foraminiferal assemblages that are dominated by the shallow infaunal component, and reveal increased but still low species diversities (fig. 5). the expansion of these two faunal parameters and the reduced organic carbon content indicate increased oxygenation, compared with the underlying maximum flooding interval. there is a sharp lithological contact between the sandy oppdalssåta member and the dark shales of the overlying slottsmøya member. the contact represents a transgressive surface, introducing the second subordinate sequence, which constitutes the upper part of the agardhfjellet formation (fig. 5). the transgressive phase of this sequence is characterized by moderate diversities and the high dominance of the shallow infaunal and potentially epifaunal morphogroups (c2 and d2). higher up in the slottsmøya member, a maximum flooding interval is developed, as shown by the slightly increased stagnation, indicated by reduced species diversity, an expanded foraminifera of dysoxic shelf deposits, spitsbergen j. nagy et al. polar research 28 2009 214–221 © 2009 the authors218 epifaunal component (mainly morphogroup d1, and secondarily b) and increased organic carbon content. the rather weakly developed base of the regressive phase is signalled by increased diversity and reduced organic carbon content. this phase continues to the upper sequence boundary marking the top of the agardhfjellet formation. conclusion callovian to kimmeridgian deposits, composing the lower half of the agardhfjellet formation in the janusfjellet section, central spitsbergen, consist mainly of shales with high to intermediate organic carbon content. deposition of the shales took place mainly under fig. 5 the janusfjellet section, with sedimentary features, morphogroup categories, diversities and oxygenation in a sequence stratigraphic framework. (lithological column redrawn and modified from århus 1998.) foraminifera of dysoxic shelf deposits, spitsbergenj. nagy et al. polar research 28 2009 214–221 © 2009 the authors 219 dysaerobic conditions. this sedimentary succession contains an essentially continuous foraminiferal record, composed almost exclusively of agglutinated taxa forming low-diversity assemblages of restricted nature. the main restricting factor was reduced access to oxygen in benthic environments, owing to the salinity-induced stratification of the water column. in the foraminiferal succession, five morphogroups (including five subgroups) have been differentiated, based on morphological features combined with inferred microhabitat preferences and feeding strategies. morphogroup a comprises forms with tubular unilocular shells, and an inferred epifaunal suspension-feeding habit. morphogroup b represents globular unilocular forms with an epifaunal, passive depositivorous mode of life. morphogroup c contains three subgroups composed of elongated, subcylindrical and multilocular taxa, with an infaunal habitat and detritivorous bacterial scavenging: subgroup c1 of uniserial forms living in shallow to deep infaunal microhabitats; subgroup c2 with spiral initial stage and uniserial final part, living as shallow infauna; and subgroup c3 of biserial, triserial or elongated trochospiral forms, with shallow to deep infaunal strategies. morphogroup d comprises spiral multilocular species living as detritivorous epifauna (potentially shallow infauna), divided into two subgroups: subgroup d1, with globular and planoconvex shape, and trochospiral coiling, including herbivores, detritivores and active omnivores; and subgroup d2, including rounded planispiral species with herbivorous, detritivorous and active bacterivorous behaviour. morphogroup e comprises flattened taxa, with a proloculus and a spiral or irregular second chamber, adapted to epifaunal to phytal, herbivorous and detritivorous modes of life. the stratigraphic distribution of the morphogroups, combined with sedimentary data and species diversities, have been employed to delineate the palaeoenvironmental evolution of the janusfjellet section, related to sealevel changes in a sequence stratigraphic framework. sea-level changes controlled the oxygenation at the different microhabitat depths at, or below, the seabed surface, as reflected by the variation in morphogroup proportions and diversity. in central spitsbergen, the agardhfjellet formation (bathonian to ryazanian in age) comprises a major depositional sequence, which can be subdivided into two subordinate sequences. these two sequences are represented in the bathonian to kimmeridgian interval studied of the janusfjellet section, although most of the regressive phase of the upper sequence is not included in this study. in both sequences the maximum flooding interval is characterized by the increased organic carbon content, the dominance of epifaunal foraminifera and the reduced species diversity: these features all indicate increased stagnation in benthic environments. the transgressive and regressive phases reveal a reduced organic carbon content, the dominance of shallow-digging infauna and an increased diversity. acknowledgements the participation of j. nagy in this research has been supported by the statoil/hydro vista programme. the contribution of m. reolid and f.j. rodríguez-tovar has been supported by the projects cgl2005-06636-c0201 and cgl2005-0316/bte, the emmi group (rnm-178, junta de andalucía) and the acción integrada 30.ai.po.1300 (university of granada–university of oslo). a grant of the universidad de jaén financed m. reolid’s short stay at the university of oslo. references århus n. 1998. palynostratigraphy of some bathonian– hauterivian sections in the arctic, with emphasis on the janusfjellet formation type section, spitsbergen. institutt for kontinentalsokkelundersøkelser og petroleumsteknologi as (iku sintef-gruppen) report 23.1252.11/01/88. trondheim: sintef petroleum research. bąk k. 2004. deep-water agglutinated foraminiferal changes across the cretaceous/tertiary and palaeocene/eocene transitions in the deep flysch environment; eastern outer carpathians (bieszczady mts, poland). in m. bubik & m.a. kaminski (eds.): proceedings of the sixth international workshop on agglutinated foraminifera. grzybowski foundation special publication 8. pp. 1–56. krakow: grzybowski foundation. chamney t.p. 1976. foraminiferal morphogroup symbol for paleoenvironmental interpretation of drill cutting samples: arctic america, albian continental margin. maritime sediments, special publication 18, 585–624. dypvik h., nagy j., eikeland t.a., backer-owe k. & johansen h. 1991. depositional conditions of the bathonian to hauterivian janusfjellet subgroup, spitsbergen. sedimentary geology 72, 55–78. jones r.w. & charnock m.a. 1985. “morphogroups” of agglutinating foraminifera. their life position, feeding habits and potential applicability in (paleo)ecological studies. revue de paléobiologie 4, 311–320. nagy j. 1992. environmental significance of foraminiferal morphogroups in jurassic north sea deltas. palaeogeography, palaeoecology, palaeoclimatology 95, 111–134. nagy j. & basov v.a. 1998. revised foraminiferal taxa and biostratigraphy of bathonian to ryazanian deposits in spitsbergen. micropaleontology 44, 217–255. nagy j., grandstein f.m., kaminski m.a. & holbourn a.e. 1995. foraminiferal morphogroups, paleoenvironments and new taxa from jurassic to cretaceous strata of thakkhola, nepal. in m.a. kaminski et al. (eds.): foraminifera of dysoxic shelf deposits, spitsbergen j. nagy et al. polar research 28 2009 214–221 © 2009 the authors220 proceedings of the fourth international workshop on agglutinated foraminifera. grzybowski foundation special publication 3. pp. 181–209. krakow: grzybowski foundation. nagy j., løfaldi m. & bäckström s.a. 1988. aspects of foraminiferal distribution and depositional conditions in middle jurassic to early cretaceous shales in eastern spitsbergen. abhandlungen der geologischen bundesanstalt 30, 297–300. reolid m., rodríguez-tovar f.j., nagy j. & olóriz f. 2008. benthic foraminiferal morphogroups of mid to outer shelf environments of the late jurassic (prebetic zone, southern spain): characterization of biofacies and environmental significance. palaeogeography, palaeoecology, palaeoclimatology 261, 280–299. severin k.p. 1983. test morphology of benthic foraminifera as a discriminator of biofacies. marine micropaleontology 8, 65–76. szydlo a. 2004. the distribution of agglutinated foraminifera in the cieszyn basin, polish outer carpathians. in m. bubik & m.a. kaminski (eds.): proceedings of the sixth international workshop on agglutinated foraminifera. grzybowski foundation special publication 8. pp. 461–470. krakow: grzybowski foundation. tyszka j. 1994. response of middle jurassic benthic foraminiferal morphogroups to dysoxic/anoxic conditions in the pieniny klippen basin, polish carpathians. palaeogeography, palaeoecology, palaeoclimatology 110, 55–81. appendix: foraminiferal species by morphogroups and subgroups morphogroup a rhizammina sp. morphogroup b thuramminoides lapilliformis nagy & basov, 1998; thuramminoides sp. morphogroup c subgroup c1 reophax sterkii haeusler, 1890 subgroup c2 ammobaculites areniferus nagy & basov, 1998; ammobaculites suprajurassicum (schwager, 1865); ammobaculites sp.; bulbobaculites aff. elongatulus (dain, 1972). subgroup c3 dorothia sp.; eomarsonella paraconica levina, 1972; verneuilina sp.; verneuilinoides aff. graciosus kosyreva, 1972; verneuilinoides sp. morphogroup d subgroup d1 ammoglobigerina canningensis (tappan, 1955); trochammina kosyrevae levina, 1972; trochammina aff. minutissima dain, 1972; trochammina misinovi levina, 1972; trochammina praerosacea nagy & basov, 1998; trochammina rostovzevi levina, 1972; trochammina sp.; trochammina spp. subgroup d2 cribrostomoides subretusus nagy & basov, 1998; cribrostomoides sp.; haplophragmoides canuiformis dain, 1972; haplophragmoides sp.; recurvoides disputabilis dain, 1972; recurvoides aff. disputabilis dain, 1972; recurvoides scherkalyensis levina, 1962; recurvoides aff. scherkalyensis levina, 1962; recurvoides sp. morphogroup e ammodiscus aff. pseudoinfimus gerke & sossipatrova, 1961; ammodiscus sp.; arenoturrispirillina jeletzkyi chamney, 1971; glomospira oxfordiana sharovskaja, 1966; glomospira semiaffixa sharovkaja, 1966. foraminifera of dysoxic shelf deposits, spitsbergenj. nagy et al. polar research 28 2009 214–221 © 2009 the authors 221 no job name b o o k r e v i e w por_121 311..312 review of the expeditions of the first international polar year 1882–83, by william barr (2008). calgary: arctic institute of north america. 417 pp. isbn 978-1-894788-03-8. it is probably safe to assume that no readers of polar research are unaware that we have just come through a fourth international polar year (ipy). all science is, or should be, based on the previous achievements of others, and thus the experiences and results of the previous three ipys (the latter ipy is known as the international geophysical year) are also in the forefront at this time. this account of the first ipy expeditions reflects that the market was ripe right now. as the ipys progressed, they became ever broader and wider in scope, both geographically and scientifically. in 2007–09 more than 60 countries and 50 000 scientists and technicians are said to have participated, to the sum of 1.2 billion usd (schiermeier 2009). at the other end of the scale, the first ipy, in 1882–83, is much easier to get to grips with. then, 11 nations established 14 major stations: 12 in the arctic or near-arctic, and two in the southern hemisphere, at south georgia and cape horn. it is useful, in addition, that the author of this book, william barr (no relation to this reviewer!), also mentions several small auxiliary expeditions, as he calls them, which were mostly one-man shows, as well as the fact that many meteorological/magnetic observations were taken by observatories worldwide, as a supplement to the main ipy programme. william barr first published this material in 1985 in connection with the 100th anniversary of the first ipy (barr 1985). the new book is a reprint of the 1985 material, including the introduction and conclusions, but with slight adjustments to the reference list, and with the addition of a helpful index. one would have liked to see the illustrations in the conclusions of the remains of three of the station sites updated with new photographs, since a lot might have happened to these arctic ruins during the past 20+ years. one of the delights of the first ipy in a historical context are the reports that appeared afterwards, which give us detailed insights into not merely the scientific work, but also the successes and tribulations—and in some cases absolute disasters—that occurred during the various expeditions. as william barr points out, the reports were published in five different languages, and no one before him had produced a monograph concerning all of the expeditions. he states clearly that the focus of his book is not so much on the scientific programmes as on the “achievements, hardships, everyday life, and weaknesses of all the expeditions involved” (p. 9). the last sentence of his introduction, which states that “these pages in the history of polar expeditions have remained blank for far too long” (p. 9) is not as appropriate now in 2008 as it was in 1985, as the ipy expeditions and stations have been the focus of various studies in recent years. as vips and others currently take oneor two-day flying trips to the heart of antarctica, it is enlightening to read of the struggle some of the first ipy expeditions had to even reach their starting point—or to get back home again afterwards. william barr starts both his introduction and his accounts with adolphus greely’s american expedition correspondence susan barr directorate for cultural heritage, p.o. box 8196 dep, no-0034 oslo, norway. e-mail: susan.barr@ra.no polar research 28 2009 311–312 © 2009 the author, journal compilation © 2009 blackwell publishing ltd 311 mailto:barr@ra.no to lady franklin bay, which was the most dramatic and ultimately disastrous of the 12 arctic expeditions. although the station was established without trouble, and ran for two whole years with great success, the relief expedition came nowhere near to fetching the 25 men in the summer of 1883. the men had to attempt to make their own way southwards through the ice-filled strait between ellesmere island and greenland. they ended up in a dire condition in starvation camp on pim island, and only seven of them were alive when help finally arrived at the end of june 1884. one of these died soon after. on the other hand, the russian expedition to ostrov sagastyr’ in the lena delta did not suffer such a gruesome fate, but it took them from december 1881 to august 1882 just to reach the site of their station, travelling overland from st. petersburg by train, sledge, carriage, river barge and steamer: a journey worth a book of its own. yet another experience of unplanned travel belongs to the dutch expedition, whose ship, the varna, got locked in the ice in the kara sea and spent the ipy there instead of at their chosen site of dickson, near the mouth of the yenisey. at the end of december 1882 the men moved into a prefabricated house on the ice, as the varna was leaking badly, and towards the end of july she sank. the men made their way by sledge and boat to the russian mainland, bringing with them all the observations and reports they had made for the ipy programme. we are in fact struck in several chapters by how different the ice conditions in mid-summer were in many of these areas compared with those of today. others again had a relatively uneventful ipy, but still their reports contain a wealth of interesting facts about their experiences, equipment, observations, extra scientific work that came in addition to the ipy programme, and connections to any local populations involved. william barr has, as mentioned above, concentrated his recounts of the expeditions on these details of the experiences of the men during the ipy. he has not attempted to analyse the whys or hows, but sticks to straightforward chronological descriptions, as related in the printed reports. there is a multitude of examples of minute detailing that could be considered trivial, but that despite this add to the understanding of these expeditions of 125 years ago—and can in many cases still be experienced today! “on the return trip they found that the spring tides had flooded the ice in places, and hence they all got wet feet; despite lockwood’s ensuring that the men changed their socks as soon as possible, private biederbick sustained a frostbitten toe, although it did not prove serious” (p. 25). as one party left another on the shore of the lena delta, “the oarsmen gave three cheers while bunge answered with three rifle shots” (p. 187). it is obvious that william barr could not, or would not, leave out the smallest detail from his translating and recounting! there are a few things to miss in this book: some of the events that are recounted beg for an explanation or an attempt at analysis. a serious rift developed between greely and the expedition surgeon dr octave pavy during spring and summer 1883 that seems to have had roots in more than just the mentioned botanical collection that greely found too poor to be of any use (p. 41). pavy was later actually placed under arrest. he died of starvation only three weeks before relief arrived at starvation camp. an analysis of the role of any local populations involved would also be interesting, but this is not the role of this book. in fact, the largest passage in the book that deviates from the straightforward reporting style of “they did this, then they did that” is contained in the chapter about the work at, or out from, ostrov sagastyr’, where the reader is treated to a long and detailed description and explanation of the geomorphology of the area (pp. 174–177, 191). the explanation is to be found in the blurb about the author on the back cover: “he is a geomorphologist by training”. there are very few maps for a book that uses many pages to describe the various journeys to and from the ipy bases, or to describe reconnaissance trips. a final negative remark, which reflects on the publisher rather than the author, is that the book is bound so tightly that it will not at any point stay open without being held that way. there is much to commend the book. not least, there are very few typographical errors. the fact that these reports are collected in one publication and in one language is the main point. the wealth of details does ensure that we have gathered here before us most of the information that can be gleaned from the general reports of the expedition, and can use this in many ways, including for some of the analyses that william barr has neither intended nor produced here. references barr w. 1985. the expeditions of the first international polar year, 1882–83. arctic institute of north america technical paper 29. calgary: arctic institute of north america. schiermeier q. 2009. in from the cold. nature 457, 1072–1077. book review polar research 28 2009 311–312 © 2009 the author, journal compilation © 2009 blackwell publishing ltd312 seabirds and fronts: a brief overview david c. schneider schneider, d. c. 1990: seabirds and fronts: a brief overview. polar research 8 , 17-21. oceanographic fronts are the sites of enhanced physical and biological activity, including locally con centrated feeding by marine birds. two general hypotheses relating marine birds to fronts have been developed. the first is that enhanced primary production at fronts increases prey supply through increased animal growth, reproduction, or immigration. the second is that prey patches develop at fronts either through behavioural responses of prey t o thermal or salinity gradients, or through interaction between prey behaviour and circulatory patterns. several recent studies support the second hypothesis. the first hypothesis, that birds benefit from enhanced primary production at fronts, has yet to be evaluated. we need a better understanding of trophic mechanisms at fronts in order to determine (1) the proportion of daily energy requirements extracted by predators at fronts; (2) the proportion of natural mortality of prey populations at fronts; and (3) the probability of contact between seabirds and point source pollutants. david c . schneider, ocean sciences centre, memorial university of newfoundland, st. johns, newfound land, canada, a l b 3x7; january 1989 (revised february 1989). a definition of ‘front’, with example few people experience any practical difficulty in identifying a front from physical oceanographic data, yet formal definition of the term has proved elusive. definitions that have been offered (bowman & esias 1978; holligan 1981; owen 1981) range from the phenomenological, empha sizing directly measureable quantities, to con ceptual, emphasizing dynamic characteristics. the definition that i will use is that of fedorov (1986): a frontal zone is a region of high spatial gradient in thermodynamic characteristics such as temperature, density, or velocity. a frontal interface is the two-dimensional distribution (surface) having the maximum spatial gradient in some property within this region. a front is the intersection of this surface with any given surface, particularly the free surface of the ocean, or an isopycnal (equal density) surface. an example will serve to illustrate. fig. 1 shows the distribution of temperature with depth along a transect beginning 6 km east of one of the pribilof islands, in the southeastern bering sea. one can see stratified water near the beginning of the transect, unstratified conditions in slightly shal lower water near the end of the transect, and a strong gradient in sea-surface temperature at the transition between these two mixing regimes, near the middle of the transect. the frontal interface, seen from the side, is the line of maximum hori zontal thermal gradient, which separates mixed and stratified water. the front, seen from the side, is the intersection of this line with the sea station 62 63 64 65 66 i i i i i i 0 0.5 i .o i .5 2 0 distance (km) fig. 1 . thermal structure along a transect running toward st. george island, in the southeastern bering sea. profile made on 5 august, 1982. profile begins at 56o38.22’ n , 169o22.32’ w. figure taken from schneider, harrison & hunt (in press). 18 d . c . schneider fig. 2. interpretation of circulation at front marking the transition from stratified to tidally mixed water. h/u’ is ratio of water depth to the cube of the tidal stream vclocity. redrawn from simpson (1981). surface. this occurs between the 7.5” c and 8” c isotherms where they intersect the sea surface (fig. 1). fig. 2 shows a further interpretation of such a feature, along dynamic lines. simpson’s (1981) interpretation is that of a lateral gradient in the balance between stabilizing (buoyant) and destabilizing (tidal mixing) forces, which result in a rapid shift from mixed to stratified water with a very small change in depth. seabird distribution in relation to fronts michitaka uda, who carried out the pioneering work on fronts (‘siome’), reported that seabirds were present in 1 out of 14 crossings of small fronts near japan (uda 1938). despite work on small scale (< 1,000 km) circulatory patterns by uda and others, the term ‘front’ did not enter the oceanographic literature until the 1960s. the term does not appear in bourne’s comprehensive review (1963), which discusses several instances of seabird congregation at current boundaries. subsequent reviews of work on pelagic birds reflect the recent increase in research on birds at fronts, as well as increasingly thorough scouring of older literature for published reports. brown (1980) listed 8 published reports of birds at fronts. bourne (1981) listed 8 published works on birds in a 3-paragraph discussion of fronts. by 1985 hunt & schneider (1987) had compiled 20 reports of seabirds at fronts. in early 1986 brown (in press) tabulated 46 reports of marine birds at fronts inferred from a variety of physical and biological properties. seabirds and fronts: a brief overview 19 statistical analysis has shown that, in general, fronts explain a significant but relatively small proportion of the observed variation in seabird abundance. in the bering sea the presence of a front explains less than 20% of the observed variability in abundance (kinder et al. 1983; schneider, harrison & hunt 1987). in the south ern ocean abrams (1985) reported stronger cor relation of bird abundance with sst gradients than with other variables, but the variances explained by sst gradients generally fell short of 20%. in the california current system briggs et al. (1987) identified sst gradients as the third most important composite variable (after distance from shore and latitude), accounting for less than 20% of the observed variance in bird abun dance. on a seasonal basis seabird abundance has been correlated with seasonal change in the frequency of surface thermal gradients in shallow waters of the continental shelf east of the gulf stream (haney & mcgillivary 1985). abundance was not correlated with seasonal frequency of thermal gradients due to eddy formation along the western side of the gulf stream (haney 1986). in the eastern bering sea, energy dissipation by pelagic birds was associated with seasonal change in the depth-integrated salinity gradient across the shelf (schneider, duffy & hunt 1988). on a smaller scale, abundance i n frontal zones was not sig nificantly greater than abundance in adjacent waters, but did depend on the strength of the physical gradient, as measured by the inverse of the width of the frontal zone (schneider, llarrison & hunt 1987). strength of a front, as measured by the inverse of the width of the frontal zone, explained 27% of the variation in abundance of seabirds in 61 frontal crossings. one potential source of low explained variance is a mismatch between the spatial scale of the front and the spatial scale at which variability in avian abundance is measured. to test this, schneider, pierotti & threlfall (in press) measured spatial variability in the abundance of murres uria aalge and puffins fratercula arctica along transects across a strong upwelling front in the southern labrador current. variability in abundance was measured at the scale of the first internal rossby radius, which is the characteristic width of the front between cold upwelled water and adjacent stratified water. the calculated width of the front was confirmed by temperature profiles. during strong upwelling, the front explained less than 15% of the observed variation in avian abundance. low explained variance in this case could not be attributed to a mismatch between the scale of the physical phenomenon and the scale of the analysis. another potential source of low explained vari ance is the length of the causal chain linking seabirds to fronts. if the causal link is through prey responses to fronts, then low explained vari ances can be expected relative to the situation of a direct causal linkage. for example, if fronts explained half of the variation in prey abundance on average, and prey explained half of the vari ation in avian abundance, then the variance in avian abundance explained by fronts (in the stat istical sense) would be 25%. several recent analy ses (schneider & piatt 1986; hunt, harrison, & cooney in press; ryan & cooper in press; erikstad this volume) have shown that prey den sity can explain more than half of the observed variation in avian abundance, often at spatial scales in excess of 5 km. these results suggest that the generally low variance in avian abundance explained by fronts may be due to intermediate levels of association along a 2 step causal chain fronts to prey, and prey to birds. feeding at fronts fronts may yet be determinants of spatial vari ation in prey capture, even though they are not major determinants of distribution. work on feeding at small frontal features in the bay of fundy (gaskin & smith 1979; brown 8 gaskin 1988) has shown that phalarope feed during the day on copepods found near the sea surface in patches of cool water generated by tidal flow over banks and ledges. these authors attributed this feeding interaction to upward flushing of cope pods, which normally migrate downward during the day. feeding also occurs at convergent areas downstream from ledges, where copepod con centrations occur near the sea surface. similarly detailed work in the bering sea has shown that murres capture euphausiids beneath the surface on the mixed side of a shallow sea front west of the pribilof islands (schneider, harrison & hunt in press). phalarope (phalaropus fulicarius) and kittiwakes (rissa fridactylu) captured injured euphausiids found swimming near the surface at the front. these authors attributed this feeding interaction to subsurface concentration of down 20 d. c . schneider ward swimming euphausiids beneath a surface convergence on the mixed side of the front (simard, d e ladurantaye & therriault 1986), upward flushing of euphausiids injured by diving murres, and concentration of injured euphausiids at the convergence associated with the thermal front at the sea surface. enhanced standing stock of phytoplankton occurs on the stratified side of the front (fig. l), while avian predation on euphausiids occurred either at the front (kit tiwakes and phalaropes), or on the mixed side of the front (murres). the bay of fundy and pribilof island studies demonstrate the importance of one of the two hypotheses relating marine birds to fronts, which is that avian predators respond to prey patches that develop through interaction between prey behaviour and circulatory patterns. detailed work at more locations will be needed to determine whether this generalization applies to other frontal systems. the importance of the alternate general hypothesis, which is that enhanced primary production increases prey supply t o birds through enhanced growth, has yet to be evaluated. w e do not yet know whether enhanced primary production at fronts is passed along to consumers such as seabirds, or simply carried elsewhere. improved understanding of concentrating mechanisms and production processes still falls short of an important goal, which is estimating the magnitude of prey mortality and predator intake in a spatially heterogeneous environment. both prey mortality and avian intake can be viewed as flux rates upward through the sea sur face with dimensions of mass per unit area per unit time (m l-* t-l where m is mass, l is length, and t is time). given the area of ocean used by pelagic populations and the difficulty in obtaining 2-dimensional measurements of seabird distri bution, some form of interpolation has to be used. one solution is t o develop a statistical model of spatial variation in upward flux of prey to avian predators. a wealth of such statistical models exists (ripley 1981). at present, we cannot expect a statistical model t o give us a very precise esti mate of flux because of the generally low explained variances reported to date. another solution, which is standard in physical and bio logical oceanography, is to construct a dynamic model that captures major features of spatial het erogeneity, such as fronts. the statistical route guarantees an immediate result in any given situa tion, with no guarantee of carryover to other situations. the alternative route, construction of a model of the feeding dynamics of marine birds in a spatially heterogeneous environment, will take longer, but does hold out the hope of general applicability and greater insight into the sources of spatial variability in trophic interaction between seabirds and their prey. a better description (and preferably, under standing) of spatial variation in energy flux to marine birds is needed in several contexts. one such context is the impact of changes in the abun dance and dispersion of fish and other prey on the foraging success and reproductive output of marine bird populations. how much of a change in either abundance or patchiness of prey must occur, and at what scale, before we can expect a change in foraging success or reproductive output of avian predators? the obverse side of this coin is: can we use seabirds as monitors of change in prey stocks, or are seabirds so loosely coupled with prey as to make them of little practical use in monitoring changes in prey abundance or dispersion? a second important context is improved understanding of natural mortality of commercially important fish species. by tradition, fisheries biologists set natural mortality at 20% per unit time, a figure that seems to work despite known temporal and spatial variation in rate of prey removal by predators. can we perhaps use birds as a convenient, highly visible group with which to investigate and attempt t o understand spatial variation in natural mortality of com mercially important fish stocks? a third important context is the impact of point-source pollutants (notably oilspills) on marine birds. we can be certain that aggregation will decrease the prob ability of contact between a spill and a group of birds, while increasing the number of encounters, given a contact. to make more specific state ments, we need a model of spatial variability in seabird abundance at the spatial scale of oil spills, which range from 10' to 1o'o metres in area. acknowledgements. i thank kjell-einar erikstad and his fam ily for their hospitality in tromse. travel t o norway was pro vided by grants from the nordic council and from the tromsll museum. r.g.b. brown made several comments that improved the manuscript. this is ocean sciences centre contribution 33. references abrams, r . w. 1985: environmental determinants of pelagic seabird distribution and abundance in the african sector of the southern ocean. j . biogeogr. 12, 473-492. seabirds and fronts: a brief overview 21 bourne, w. r. p. 1963: a review of occanic studics of the biology of seabirds. proc. x i i i infernat. ornithol. congr., bourne, w. r. p. 1981: some factors underlying thedistribution of seabirds. pp. 119-134 in cooper, j. (ed.): proceedings of the symposium on b i r h of &he sea and shore, 1979. south african seahird group, cape town. bowman, m. & esias, w. 1978: oceanic fronts in coastal processes. springer-verlag, berlin. 114 pp. briggs, k. t., tyler, w. b., lewis, d. b. & carlson, d . r. 1987: bird communities at sea off california: 1975-1983. studies in avian biology 11, 1-74. brown, r. g. b. 1980: seabirds as marine animals. pp. 1 4 9 in burger, j . , olla, b. l. & winn, h. e . (eds.): behauior of marine animals. plenum press, new york. brown, r. g . b. 1988: zooplankton patchiness and seabird distributions. proc. x i x internat. ornithol. congr., 1001 1009. brown, r. g. b. & gaskin, d. e. 1988: the pelagic ecology of grey and red-necked phalarope phalaropus fulicarius and p . lobatus in the bay of fundy, eastern canada. ibis 130, 234-250. fedorov, k. n . 1986: the physical nature and structure of oceanic fronts. springer-verlag, berlin. 333 pp. gaskin, d. e. & smith, g. j . d. 1979 observations on marine mammals, birds and environmental conditions in the head harbour region of the bay of fundy. pp. 69-86 in scarrett, d. j. (cd.): evaluation of recent data relative to oil s p i h in the passamaquoddy area. tech. rep. 901. dfo and environmcnt canada, st. andrews, new brunswick. haney, j. c. 1986: seabird affinities for gulf stream frontal eddies: responses of mobile marine consumers to episodic upwelling. j . mar. res. 4 4 , 361-384. haney, j. c. & mcgillivary, p. a. 1985: midshelf fronts in the south atlantic bight and their influence on seabird distri bution and seasonal abundance. biol. oceanogr. 3, 401430. holligan, p . m. 1981: biological implications of fronts on the northwest europcan continental shelf. phil. trans. roy. society a302, 547-562. hunt, g. l., jr., harrison, n . m. & cooney, t. in press: foraging of least auklets: the influence of hydrographic structure and prey abundance. studies in avian biology. 831-854. hunt, g. l., jr. & schneider, d. c. 1987: scale-dependent processes in the physical and biological environment of mar ine birds. pp. 7-41 in croxall, j . (ed.): seabirds: feeding biology and role in marine ecosystems. cambridge uni versity press, cambridge. kinder, t . h., hunt, g. l., jr., schneider, d. c. & schumacher, j. d. 1983: correlation between seabirds and oceanic fronts around the pribilof islands, alaska. estuarine, coast. shelf sci. 16, 309-319. owen, r. w. 1981: fronts and cddies in the sca: mechanisms, interactions and biological effects. pp. 197-233 in longhurst, a. r. (ed.): analysis ofmarine ecosystems. academic press, new york. riplcy, b. d. 1981: spatia/ statistics. academic press, london. 252 pp. ryan, p. g. &cooper, j . 1990: the distribution and abundance of seabirds in relation to antarctic krill in the prydz bay region, antarctica. p d a r biology (in press). schneider, d. c., duffy, d. c. & hunt, g. l., jr. 1988: cross shelf gradients in the abundance of pelagic birds. proc. xix internat. ornifhol. congr., 976-981. schneider, d. c., harrison, n. m. & hunt, g. l., jr. 1987: variation in the occurrence of marine birds at fronts in the bering sea. estuarine, coast. shelf sci. 25, 135-141. schneider, d. c., harrison, n. m. & hunt, g. l., jr. in press: seabird diet at a bathymetric confluence near the pribilof islands, alaska. studies in auian biology. schneider, d. c. & piatt, j. f. 1986: scale-dependent cor relation of seabirds with schooling fish in a coastal ecosystem. mar. eco1.-progr. ser. 32,237-246. schneider, d. c., pierotti, r. & threlfall, w. in press: alcid patchiness and flight direction near a colony in eastern new foundland. studies in avian biology. simard, y . , de ladurantaye, k. & therriault, j . 1986: aggre gation of euphausiids along a coastal shelf in an upwelling environment. mar. ecol-progr. ser. 32, 203-215. simpson, j . h. 1981: the shelf-sea fronts: implications of their existence and behaviour. phil. trans. roy. soc. lond. a302, 531-546. uda, m. 1938: researches in ‘siome’ or current rip in the sea. geophys. magazine 11,307-372. response of antarctic sea-ice algae to an experimental decrease in ph: a preliminary analysis from chlorophyll fluorescence imaging of melting ice research note response of antarctic sea-ice algae to an experimental decrease in ph: a preliminary analysis from chlorophyll fluorescence imaging of melting ice katerina castrisios a, andrew martin a, marius n. müllerb, fraser kennedy a, andrew mcminna & ken g. ryanc ainstitute for marine and antarctic studies, university of tasmania, hobart, australia; bdepartment of oceanography, federal university of recife, cidade universitária, recife, brazil; cschool of biological sciences, victoria university of wellington, wellington, new zealand abstract microorganisms confined to annual sea ice in the southern ocean are exposed to highly variable oxygen and carbonate chemistry dynamics because of the seasonal increase in biomass and limited exchange with the underlying water column. for sea-ice algae, physiological stress is likely to be exacerbated when the ice melts; however, variation in carbonate speciation has rarely been monitored during this important state-transition. using pulse amplitude modulated fluorometry (imaging-pam, walz), we documented in situ changes in the maximum quantum yield of photosystem ii (fv/fm) of sea-ice algae melting out into seawater with initial ph values ranging from 7.66 to 6.39. although the process of ice-melt elevated seawater ph by 0.2–0.55 units, we observed a decrease in fv/fm between 0.02 and 0.06 for each unit drop in ph during real-time fluorescence imaging. these results are considered preliminary but provide context for including carbonate chemistry monitoring in the design of future sea ice state-transition experiments. imaging-pam is a reliable technology for determining fv/fm, but is of limited use for obtaining additional photosynthetic parameters when imaging melting ice. keywords antarctica; imaging-pam; photophysiology; carbonate chemistry abbreviations i-pam: imaging pulse amplitude modulated fluorometry; par: photosynthetically active radiation; uv-b: ultraviolet radiation introduction high-latitude waters of the southern ocean will be among the first places on earth to experience the effects of anthropogenic-induced climate change, including ocean warming and acidification (fabry et al. 2008; doney 2010). in the mcmurdo sound region of antarctica, the mean seawater ph is currently 8.05, with a seasonal range of 0.42 units. by 2100 ph is predicted to drop below 7.9 and exhibit greater annual variability (kapsenberg et al. 2015). the associated change in seawater carbonate speciation (increased co2, hco3 −, h+; decreased co3 2−) and its effect on polar ocean primary production are not fully resolved. shelf waters surrounding antarctica are effective sinks for anthropogenic carbon emissions, and increased oceanic co2 availability could facilitate faster rates of photosynthesis and growth in marine photoautotrophs (riebesell et al. 1993). however, dissolved inorganic carbon is rarely in short supply in planktonic ecosystems and many taxa, including diatoms, possess carbon-concentrating-mechanisms that are highly efficient at elevating co2 at the site of rubisco (reinfelder 2011; kranz et al. 2015). to date, incubation experiments with southern ocean phytoplankton have demonstrated a variable response to elevated co2 (müller et al. 2015). some phytoplankton down-regulate carbon-concentrating mechanisms, a response that potentially liberates energy that can be reallocated to other functions (raven et al. 2011), but this does not always equate to increased growth rates and primary production (torstensson et al. 2012; trimborn et al. 2013; mcminn et al. 2014; young et al. 2015). for microbes confined to annual sea ice in the southern ocean the situation is significantly different. because of the seasonal increase in biomass and limited exchange with the underlying water column, there are a number of dramatic chemical changes that take place within the ice matrix, specifically variable co2, o2 and ph dynamics (thomas & dieckmann 2002; thomas & papadimitriou 2003). efficient physiological acclimation that sustains photosynthesis within the ice is therefore critically important (arrigo & thomas 2004; mcminn et al. 2005), but the influence of ph on algal physiology is not clearly understood. experimental work with cells growing near the upper surface of the ice demonstrates that increased co2 enhances growth by approximately 20%, provided that cells are incubated at a constant ph of ca. 8.0 (mcminn et al. 2014). if microbes are exposed to decreasing ph (< ca. 7.2), then the increase in h+ ions has been shown to reduce growth rates by almost 50% (mcminn et al. 2014). contact andrew martin andrew.martin@utas.edu.au institute for marine and antarctic studies, university of tasmania, hobart, private bag 129, hobart, tasmania 7001, australia polar research, 2018 vol. 37, 1438696 https://doi.org/10.1080/17518369.2018.1438696 © 2018 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0001-6085-9077 http://orcid.org/0000-0001-8260-5529 http://orcid.org/0000-0003-1796-0764 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2018.1438696&domain=pdf a general understanding of how sea ice impacts the carbon cycle and ocean–atmosphere co2 exchange in polar regions is now emerging (see rysgaard et al. 2011; fransson et al. 2015), but the associated changes in carbonate chemistry due to melting ice remain poorly characterized (bates et al. 2014). the bottom-ice algae that dominate the biological assemblages in antarctic fast-ice undergo considerable physiological stress during the melt process. this ecological state-transition has been well studied with respect to uv-b and par (e.g., palmisano & sullivan 1983; mock & kroon 2002; mcminn et al. 2010; ryan et al. 2012), temperature (e.g., arrigo & thomas 2004; mock & thomas 2005; ralph et al. 2005) and salinity (e.g., arrigo & sullivan 1992; ralph et al. 2007; ryan et al. 2011; ugalde et al. 2014), but not to associated changes in ph. the evolution of distinct ph environments within sea ice has only recently been described by utilizing an experimental outdoor facility (hare et al. 2013). analysis of vertical ph profiles revealed a consistent c-shaped pattern with highest ph values (>9) in both top and bottom sections of the ice and lowest ph (ca. 7) in interior ice sections, albeit in the absence of biological activity. in spring and summer, microbial photosynthetic activity depletes dissolved co2 and ph rises. however, it is not known how variation in ph influences algal photophysiology with respect to freeze–thaw dynamics. a particularly useful tool for correlating algal photophysiology with changing environmental conditions has been pulse amplitude modulated fluorometry. this technique is based on measuring variable chlorophyll a fluorescence, which provides a unique indicator of intracellular activity in photoautotrophs (schreiber 2004; ralph & gademan 2005; baker 2008). mcminn et al. (2003) pioneered the use of pulse amplitude modulated fluorometry in antarctica, and various configurations of the technology have now been employed for the in vitro analysis of ice shavings, extracted brines and melted ice cores (e.g., ryan et al. 2004; ralph et al. 2007; kennedy et al. 2012; martin et al. 2012). i-pam (walz, germany) provides unprecedented twodimensional in situ imagery which allows physiological stress to be measured with significantly less disruption of the physical habitat (ryan et al. 2011; hawes et al. 2012; lund-hansen et al. 2014). this technology has only been employed once in antarctica and with mixed success (ryan et al. 2011), but the capacity to generate in situ data warrants further investigation. in this preliminary study, our objectives were to expose sea-ice algae to changes in ph to determine whether short-term (8-h) exposure to reduced ph influences algal photophysiology (experiment 1) and to quantify changes in ph that occur during the melt process (experiment 2). we also determine whether imaging fluorescence is a viable technology to resolve changes in algal photophysiology during state-transition experiments. materials and methods study area bottom-ice algae were collected from 1.8 m thick annual fast-ice at cape evans, mcmurdo sound, antarctica (77°38ʹs, 166°24ʹe), between 27 november and 1 december 2013 (fig. 1). limited incubation space in the field laboratory required that the experiment be carried out over four days; one day per ph treatment and one day for the control. the order of the treatments and control was selected at random to minimize any effect of in situ change in the microbial community. two ice cores were required each day and these were obtained by drilling to within 300 mm of the ice/water interface using a powered ice auger (jiffy), and then using a figure 1. location and schematic representation of sampling site at cape evans, mcmurdo sound, antarctica. the image on the right shows a typical ice sample melting into manipulated seawater. the ice has been imaged using minimal fluorescence, fo, with an i-pam. the circles represent regions of relatively high algal biomass. 2 k. castrisios et al. mark v corer (kovacs) to extract the last section of ice from the bottom of each hole. once clear of the ice, each core was immediately transferred to a black polythene bag to protect the algae from light shock and transported a short distance to the field laboratory inside a cool box. experimental set-up each day, the two extracted ice cores were cut, under minimallight,intothreepieces40mm×40mm×20mm thick to include bottom-ice algae. the six blocks of ice were then dark-adapted for 30 min in a cool box maintained at about 0°c before being placed into individual airtight plastic containers with clear plastic covers containing 112 ml of seawater (filtered to 0.7 µm, −1.8°c). the seawater had previously been collected from a local dive hole. seawater ph was reduced by adding hcl which changed the total alkalinity (at) while keeping the dissolved inorganic carbon (ct) concentration relatively constant. untreated seawater was used as a control treatment (ph 7.66, pco2 1651 μatm). the three ph treatments ranged from 7.32 to 6.39 (free scale). during the daily incubation, the six plastic containers containing ice core samples were placed in a temperature controlled water bath at 0.5°c ± 0.2°c for 480 min. an artificial light source comprising a 3 × 4 array of led lamps suspended 800 mm above the water bath was used to provide an incubation irradiance of 40 μmol photons m−2 s−1. three of the plastic containers were periodically opened in order to assess algal photophysiology (experiment 1). constant agitation of the seawater inside the containers (generated by circulation of the liquid in the water bath) ensured that the ice was bathed in seawater and prevented stratification as the ice melted. the other three containers, also exposed to light, remained closed for the duration of the experiment to examine the change in carbonate chemistry due to the melt process and biological activity (experiment 2). experiment 1: photophysiology variable chlorophyll fluorescence was measured using the maxi version of the i-pam instrument (walz). the i-pam maxi can resolve the distribution of chlorophyll a and activity of photosystem ii in two dimensions over an area of 130 mm × 100 mm and the user has the option of employing pulse-modulated excitation for the generation of rapid light curves, actinic light and saturation pulses. the blue excitation light supplied by the i-pam is centred on 450 nm, which is a wavelength that is characteristic of the blue-green spectra at the bottom of the ice (lundhansen et al. 2014). the saturation pulse method was used to determine minimum (fo) and maximum (fm) fluorescent yields (fv/fm) of the dark-adapted ice samples. the i-pam operational software includes an area-of-interest function that was used to select three specific locations on each block of ice to obtain fv/fm measurements. selecting locations on each block of ice was a semi-random process; data were only acquired from areas-of-interest where fo was >0.15. fo is a measure of minimum fluorescence intensity of algae in the dark-adapted state where intensity is proportional to biomass. fluorescent measurements of the blocks of ice were made by first removing the lid and then carefully aligning each plastic container on the stage of the i-pam by using the live near-infrared imaging feature. after obtaining fluorescence measurements the lid was placed back on the container and immediately returned to the water bath. this process was performed in the dark in a field laboratory maintained at ca. 4°c and took no more than 30 s per sample. an initial assessment of fv/fm was made before the ice was added to the containers and then at 30-min intervals up to 120 min. thereafter, fluorescence imaging was carried out at 240, 360 and 480 min. samples were dark-adapted in the water bath for 10 min prior to fluorescence analysis (10–15 min is typical for dark-adapting sea ice algae (ralph et al. 2007; mcminn et al. 2010)) by turning off the overhead light array. the generation of rapid light curves was attempted, but like ryan et al. (2011), we could not achieve the required saturation to derive the necessary parameters. experiment 2: carbonate chemistry samples for ct and at were taken from replicates of the melted ice at the end of each experimental run. ct samples were filtered through 0.2 μm sterile filters into 12.5 ml exetainers (labco), poisoned with hgcl2 and sealed air tight. at samples were filtered through gf/f filters, poisoned with hgcl2 and stored in 250 ml polythene flasks. the programme co2sys version 1.05 (lewis & wallace 1998) was used to calculate the carbonate system using the dissociation constants for carbonic acid (roy et al. 1993). ct and at samples were analysed as the mean of triplicate measurements with the infrared detection method using a dissolved inorganic carbon analyser (apollo scitech, model as-c3) and the potentiometric titration method for at. data were corrected to certified reference materials (scripps institution of oceanography, usa). consecutive measurements of the dickson standard resulted in an average precision of >98% for both ct and at. ice algal species composition a 10 ml sample of three randomly selected core sections was fixed in 0.5% gluteraldehyde. a 0.5 ml polar research 3 aliquot from each sample was prepared using a special settling chamber and cells were examined using a zeiss compound microscope with standard optics. microalgae were counted from 10 randomly selected fields of view. data analysis to examine potential changes in maximum quantum yield (fv/fm) relative to ph and incubation period, a linear third-order polynomial model was fitted to the data using the statistical package rstudio (version 0.98.939; rstudio team). results and discussion this is the first study to employ chlorophyll imaging fluorometry to examine the effect of decreased ph on algal photophysiology. experiments were conducted in a remote antarctic field camp with limited facilities to replicate a precisely controlled laboratory environment. a broad initial ph regime was chosen (6.39–7.66) to allow for shifts in carbonate chemistry induced by outgassing and experimental handling procedures, specifically the removal of plastic lids to perform i-pam measurements, which exposed ice samples to the atmosphere (3.5 min during the 8-h incubation, experiment 1). the sea ice at cape evans in mcmurdo sound was 1.8 m thick in november–december 2013, with no snow cover. the bottom-ice community was dominated by the pennate diatom nitzschia stellata, which accounted for >90% of the observed cells. other taxa present within the ice included fragilariopsis spp., gyrosigma sp., navicula directa and n. glaciei. photophysiology the ratio fv/fm derived using the saturation pulse method is a sensitive indicator of photosynthetic potential in photoautotrophs. prior to incubation, fv/fm of the sea-ice algae ranged from 0.37 to 0.52, which is indicative of a relatively healthy community that was well-acclimated to the light climate within the ice matrix (table 1). at the incubation temperature of 0.5°c, it took approximately two hours for the ice to completely melt, during which time the ice was imaged four times. the post-melt fv/fm values obtained at 240, 360 and 480 min were derived from algae that were suspended in seawater (fig. 1). the maximum quantum yield of photosystem ii declined in all treatments and the control during the period of ice-melt (table 1). this response is indicative of the physiological stress associated with both the transition from semi-solid ice to liquid water and exposure to light. a similar response was documented by ryan et al. (2011) when sea-ice algae were first examined using imaging fluorescence. these authors also identified salinity to be a significant costressor, particularly at concentrations <24. to prevent saline shock in the current study, we used smaller blocks of ice. as a result, the salinity only decreased from 34 to ca. 28 by the end of the experiment (table 2) and any effect on fv/fm is considered to be minimal. to determine whether ph also influenced the photosynthetic yield measurements, we fitted a linear third-order polynomial model to the fluorescence data. this model accounted for the variation in initial fv/fm that was evident in the ph 7.66 treatment (table 2). by retaining only the first order term in the model, the analysis revealed that for each unit drop in ph, the change in yield of photosystem ii decreased over time by between 0.02 and 0.06 (t (10) = 4.06, r2 = 0.623, p < 0.01; fig. 2). experimental manipulation of ph has two main effects on marine photoautotrophs, specifically acidification (increased h+) and carbonation (elevated co2). relative to ambient oceanic conditions, the former generally has a negative effect on algal physiology, the latter a positive effect. this results in an optimum curve with respect to the physiological response in marine microbes (see bach et al. 2015). mcminn et al. (2014) were the first to examine how algae released from the ice matrix respond to manipulated carbonate chemistry, and while a decline in fv/fm was observed in brine algae exposed to a ph regime that varied from 8.66 to 7.19, the trend was not significant. more recently, coad et al. (2016) melted algae from the snow/ice interface region of annual pack-ice into a ph regime that varied from 7.82 to 7.0, but only modest impacts on photophysiology were documented after seven days. because of this non-response in photosynthetic parameters, mcminn et al. (2017) have questioned the use of pulse amplitude modulated fluorometry to measure stress response in ph/co2 experiments. in this study, we adopted a more acidic regime and did observe a significant response to reduced ph. however, the relationship between h+ concentration and fv/fm has yet to be substantiated. previous studies that have included growth rates (e.g., mcminn et al. 2014; mcminn et al. 2017) have shown table 1. response of sea-ice algae exposed to variable ph during ice-melt. maximum quantum yield (fv/fm) was determined using imaging fluorescence (i-pam). each value is the mean with standard error in parentheses, n = 3. initial phfree time (min) 6.39 6.84 7.32 control (7.66) 0 0.52 (0.01) 0.49 (0.01) 0.49 (0.02) 0.37 (0.02) 30 0.50 (0.02) 0.45 (0.02) 0.46 (0.03) 0.36 (0.02) 60 0.50 (0.02) 0.47 (0.01) 0.44 (0.02) 0.37 (0.02) 90 0.51 (0.03) 0.47 (0.01) 0.43 (0.02) 0.37 (0.02) 120 0.50 (0.02) 0.42 (0.01) 0.41 (0.01) 0.35 (0.04) 240 0.46 (0.02) 0.45 (0.01) 0.45 (0.01) 0.35 (0.03) 360 0.45 (0.01) 0.43 (0.01) 0.41 (0.02) 0.35 (0.04) 480 0.44 (0.02) 0.42 (0.02) 0.43 (0.02) 0.34 (0.02) 4 k. castrisios et al. that a decline in growth is attributed to high h+ concentration rather than high co2. this suggests that h+ concentration can influence intracellular ph and/or changes in membrane potential, energy partitioning and enzyme activity (beardall & raven 2004; suffrian et al. 2011), and this has a subsequent effect on photosynthetic performance. although the decline in photosynthetic potential observed during ice-melt was most pronounced in cells exposed to the lowest ph (6.39), fv/fm was consistently higher compared to the less acidic treatments and the control (table 2). this highlights the fact that a significant increase in h+ ions has a minimal short-term effect on fv/fm, as assessed using an i-pam. the relative change in fv/fm described by the model must be considered a subtle trend, but it is potentially indicative of a more significant stress response had the experiment been conducted over a longer time period. importantly, we did not observe a threshold at which point algal photophysiology is compromised to the extent observed when other stressors such as light (ralph et al. 2007; ryan et al. 2009; ryan et al. 2011), temperature (ralph et al. 2005; rajanahally et al. 2014) or salinity (ryan et al. 2004; ralph et al. 2007; ryan et al. 2011) are manipulated. carbonate chemistry the aim of experiment 2 was to provide a rudimentary insight into the changes in ph that occur as the sea ice melts. the post-incubation carbon chemistry data (table 2) was obtained from plastic containers that were not opened during the incubation period and for that reason the data are not directly comparable with the photophysiology experiment. by the end of the incubation period, ice-melt and the biological activity of liberated microbes had increased the seawater ph in all treatments and the control, from 0.2 to 0.55 units. this provides a very basic illustration of the dynamic that occurs at the receding ice edge which has recently been described at an ecologically relevant scale in the arctic ocean as part of the nasa icescape project (bates et al. 2014). the carbonate chemistry of below-ice interface melt waters at 19 ice stations was variable and difficult to predict, but generally exhibited higher ph and lower pco2 compared to the co-located mixed layer beneath. although we collected ice cores from a discrete area of sea ice, there was significant variation in post-melt measurements of ct and at, presumably due to variability in biomass and the ratio of ice to figure 2. linear third-order polynomial model of maximum quantum yield (fv/fm) for each ph treatment and the control contrasting the difference between start and end-point measurements. the error variance is represented by the dark grey band. table 2. carbonate chemistry of co2 manipulation experiment utilizing bottom-ice algae at cape evan, 2013. the end of experiment data (8-h incubation) illustrates the changes in carbonate chemistry associated with ice-melt. the unit for ct, at and co2 is μmol kg −1. the unit for pco2 is μatm. initial seawater chemistry phfree salinity ct sd at sd pco2 co2 control 7.66 34.67 2303 9 2396 40 1651 44 start of experiment end of experiment ph free salinity ph free salinity ct sd at sd pco2 co2 control 7.66 34.67 control 8.15 28.07 2175 220 2493 50 593 16 7.32 34.73 7.52 27.33 2230 260 2282 114 4335 120 6.84 34.70 7.14 30.00 1983 175 1860 19 6547 174 6.39 34.80 6.94 28.67 1879 101 1879 180 10,177 273 polar research 5 brine volume in each block of ice. however, algal cellular physiology is not directly affected by variation in ct and at; of significance is the change in the total concentration of ions (co2, hco3, co3 and h+) that are made available. in situ fluorescence imaging the practice of actively releasing cells from the ice matrix is likely to modify or damage cellular physiology and ice-associated microbes should ideally be studied in situ. while this has been successfully achieved using oxygen electrodes (e.g., kühl et al. 2001; trenerry et al. 2002; mcminn et al. 2012) and habitat modification experiments (martin et al. 2011), options for physiology experiments are limited. in situ fluorescence imaging is of significant interest because algal photophysiology can be assessed at a spatially relevant scale, specifically the assessment of cells inside the microscopic brine channels that characterise the ice matrix. although our measurements are only indicative of ablation at the receding ice edge in the austral summer, real-time measurements are considered important because this state-transition, and exposure to physico-chemical stress, occurs relatively quickly. like ryan et al. (2011), we could not use the i-pam to generate rapid light curves and obtain the additional photosynthetic parameters retrmax, alpha, and ek. the maximum rate of electron flow from photosystem ii to photosystem i (etrmax) is of particular interest because it describes photosynthetic capacity. the initial ice dimensions used by ryan et al. (2011) were 70 mm × 60 mm × 15 mm and we reduced this to 40 mm × 40 mm × 20 mm (i.e., a 50% reduction in volume). however, the relative abundance of algae within the ice was still too high. the rapid light curves do not reach an asymptote because multiple layers of densely packed cells confound the required response to the increasing irradiance emitted by the fluorometer. to an extent, this problem has now been addressed by hawes et al. (2012), who successfully generated rapid light curves rlcs during fluorescence imaging of newly forming arctic sea ice with a relatively low biomass. these authors used the i-pam mini (walz), which has a reduced imaging area of 30 × 23 mm, and integrated the fluorescence data obtained from a series of ice core sections that were 2 mm thick. working with such thin sections is not a practical solution in state-transition experiments because of rapid ice-melt. for this reason we suggest the i-pam maxi is only relevant for collecting in situ measurements of maximum quantum yield (fv/fm). conclusion this is the first study to document statistically significant photophysiological stress in sea-ice algae due to decreased ph. future experiments will require greater experimental precision, but the data provide context for assessing the relative importance of carbonate chemistry to sea-ice ecophysiology. importantly, the physiological stress associated with rapid exposure to high light and low salinity during ice-melt is significant and the compound stress associated with the projected decline in ph in antarctic coastal waters has the potential to shift environmental conditions beyond physiologically tolerable levels (mcminn et al. 2014). a mechanistic understanding of how ice-associated microbes adapt to freeze–thaw dynamics requires a clearer insight into how ph influences algal physiology. for this reason, we suggest that carbonate chemistry monitoring should be included in the design of future multi-stressor statetransition experiments. acknowledgements we thank antarctica new zealand for logistic support and the staff at scott base for their help in preparation and deployment to the field. disclosure statement no potential conflict of interest was reported by the authors. funding we acknowledge victoria university of wellington grant 100241 for financial support. orcid katerina castrisios http://orcid.org/0000-0001-6085-9077 andrew martin http://orcid.org/0000-0001-8260-5529 fraser kennedy http://orcid.org/0000-0003-1796-0764 references arrigo k.r. & sullivan c.w. 1992. the influence of salinity and temperature covariation on the photophysiological characteristics of antarctic sea ice microalgae. journal of phycology 28, 746–756. arrigo k.r. & thomas d.n. 2004. large scale importance of sea ice biology in the southern ocean. antarctic science 16, 471–486. bach l.t., riebesell u., gutowska m.a., federwisch l. & schulz k.g. 2015. a unifying concept of coccolithophore sensitivity to changing carbonate chemistry embedded in an ecological framework. progress in oceanography 135, 125–138. 6 k. castrisios et al. baker n.r. 2008. chlorophyll fluorescence: a probe of photosynthesis in vivo. annual review of plant biology 59, 89–113. bates n.r., garley r., frey k.e., shake k.l. & mathis j.t. 2014. sea–ice melt co2-carbonate chemistry in the western arctic ocean: meltwater contributions to air–sea co2 gas exchange, mixed-layer properties and rates of net community production under sea ice. biogeosciences 11, 6769–6789. beardall j. & raven j.a. 2004. the potential effects of global climate change on microalgal photosynthesis, growth and ecology. phycologia 43, 26–40. coad t., nomura d., mcminn a. & martin a. 2016. effect of elevated co2 concentration on the photophysiology and growth of microalgae in antarctic pack ice communities. deep-sea research part ii topical studies in oceanography 131, 160–169. doney s.c. 2010. the growing human footprint on coastal and open-ocean biogeochemistry. science 328, 1512– 1516. fabry v.j., seibel b.a., feely r.a. & orr j.c. 2008. impacts of ocean acidification on marine fauna and ecosystem processes. journal of marine science 65, 414–432. fransson a., chierici m., nomura d., granskog m.a., kristiansen s., martma t. & nehrke g. 2015. effect of glacial drainage water on the co2 system and ocean acidification state in an arctic tidewater-glacier fjord during two contrasting years. journal of geophysical research—oceans 120, 2413–2429. hare a.a., wang f., barber d., geilfus n.-x., galley r.j. & rysgaard s. 2013. ph evolution in sea ice grown at an outdoor experimental facility. marine chemistry 154, 46–54. hawes i., lund-hansen l.c., sorrell b.k., nielson m.h., borzák r. & buss i. 2012. photobiology of sea ice algae during initial spring growth in kangerlussuaq, west greenland: insights from imaging variable chlorophyll fluorescence of ice cores. photosynthesis research 112, 103–115. kapsenberg l., kelley a.l., shaw e.c., martz t.r. & hofmann g.e. 2015. near-shore antarctic ph variability has implications for the design of ocean acidification experiments. scientific reports 5, article no. 10497, doi: 10.1038/srep10497. kennedy f., mcminn a. & martin a. 2012. effect of temperature and sea ice on the photosynthetic efficiency and morphotype of phaeocystis antarctica. journal of experimental marine biology and ecology 429, 7–14. kranz s.a., young j.n., hopkinson b., goldman j.a.l., tortell p.d. & morel f.m.m. 2015. low temperature reduces the energetic requirement for the co2 concentrating mechanism in diatoms. the new phytologist 205, 192–201. kühl m., glud r.n., borum j., roberts r. & rysgaard s. 2001. photosynthetic performance of surface-associated algae below sea ice as measured with a pulse-amplitudemodulated (pam) fluorometer and o2 microsensors. marine ecology progress series 223, 1–14. lewis e. & wallace d.w.r. 1998. program developed for co2 system calculations. ornl/cdiac-105. oak ridge, tn: carbon dioxide information analysis center, oak ridge national laboratory, us department of energy. lund-hansen l.c., hawes i., sorrell b.k. & nielsen m.h. 2014. removal of snow cover inhibits spring growth of arctic ice algae through physiological and behavioural effects. polar biology 37, 471–481. martin a., anderson m.j., thorn c., davy s.k. & ryan k. g. 2011. response of sea-ice microbial communities to environmental disturbance: an in situ transplant experiment in the antarctic. marine ecology progress series 424, 25–37. martin a., mcminn a., heath m., hegseth e. & ryan k.g. 2012. the physiological response to increased temperature in over-wintering sea ice algae and phytoplankton in mcmurdo sound, antarctica and tromsø sound, norway. journal of experimental marine biology and ecology 428, 57–66. mcminn a., ashworth c., bhagooli r., martin a., salleh s., ralph p. & ryan k.g. 2012. antarctic coastal microalgal primary production and photosynthesis. marine biology 159, 2827–2837. mcminn a., martin a. & ryan k.g. 2010. phytoplankton and sea ice algal biomass and physiology during the transition between winter and spring (mcmurdo sound, antarctica). polar biology 33, 1547–1556. mcminn a., müller m.n., martin a. & ryan k.g. 2014. the response of antarctic sea ice algae to changes in ph and co2. plos one 9, e86984, doi: 10.1371/journal. pone.0086984. mcminn a., müller m.n., martin a., ugalde s.c., lee s., castrisios k. & ryan k.g. 2017. effects of co2 concentration on a late summer surface sea ice community. marine biology 164, article no. 87, doi: 10.1007/s00227017-3102-4. mcminn a., pankowski a. & delfatti t. 2005. effect of hyperoxia on the growth and photosynthesis of polar sea ice microalgae. journal of phycology 41, 732–741. mcminn a., ryan k.g. & gademann r. 2003. diurnal changes in photosynthesis of antarctic fast ice algal communities determined by pulse amplitude modulation fluorometry. marine biology 143, 359–367. mock t. & kroon b.m. 2002. in situ primary production in young antarctic sea ice. hydrobiology 470, 127–132. mock t. & thomas d.n. 2005. recent advances in sea-ice microbiology. environmental microbiology 7, 605–619. müller m.n., trull t.w. & hallegraeff g.m. 2015. differing response of three southern ocean emiliania huxleyi ecotypes to changing seawater carbonate chemistry. marine ecology progress series 531, 81–90. palmisano a.c. & sullivan c.w. 1983. sea-ice microbial communities (simco). i. polar biology 2, 171–177. rajanahally m.a., sim d., ryan k.g. & convey p. 2014. can bottom ice algae tolerate irradiance and temperature changes? journal of experimental marine biology and ecology 461, 516–527. ralph p.j. & gademan r. 2005. rapid light curves: a powerful tool to assess photosynthetic activity. aquatic botany 82, 222–237. ralph p.j., mcminn a., ryan k.g. & ashworth c. 2005. short-term effect of temperature on the photokinetics of microalgae from the surface layers of antarctic pace ice. journal of phycology 41, 763–769. ralph p.j., ryan k.g., martin a. & fenton g. 2007. melting out of sea ice causes greater photosynthetic stress in sea ice algae than freezing in. journal of phycology 43, 948–956. raven j.a., giordano m., beardall j. & maberly s.c. 2011. algal and aquatic plant carbon concentrating mechanisms in relation to environmental change. photosynthesis research 109, 281–296. reinfelder j.r. 2011. carbon concentrating mechanisms in eukaryotic marine phytoplankton. annual review of marine science 3, 291–315. polar research 7 https://doi.org/10.1038/srep10497 https://doi.org/10.1038/srep10497 https://doi.org/10.1371/journal.pone.0086984 https://doi.org/10.1371/journal.pone.0086984 https://doi.org/10.1007/s00227-017-3102-4 https://doi.org/10.1007/s00227-017-3102-4 riebesell u., wolf-gladrow d.a. & smetacek v. 1993. carbon dioxide limitation of marine phytoplankton growth rates. nature 361, 249–251. roy r.n., roy l.n., vogel k.m., porter-moore c., pearson t., good c., millero f.j. & campbell d.m. 1993. the dissociation constants of carbonic acid in seawater at salinities 5 to 45 and temperatures 0 to 45°c. marine chemistry 44, 249–267. ryan k.g., cowie r., liggins e., mcnaughtan d., martin a. & davy s.k. 2009. the short-term effect of irradiance on the photosynthetic properties of antarctic fast-ice microalgal communities. journal of phycology 45, 1290– 1298. ryan k.g., mcminn a., hegseth e. & davy s.k. 2012. the effects of ultraviolet-b radiation on antarctic sea-ice algae. journal of phycology 48, 74–84. ryan k.g., ralph p.j. & mcminn a. 2004. photoacclimation of antarctic bottom ice algal communities to lowered salinities during melting. polar biology 27, 679–686. ryan k.g., tay m.l., martin a., mcminn a. & davy s.k. 2011. chlorophyll fluorescence imaging analysis of the responses of antarctic bottom-ice algae to light and salinity during melting. journal of experimental marine biology and ecology 399, 156–161. rysgaard s., bendtsen j., delille b., dieckmann g.s., glud r., kennedy h., mortensen j., papadimitriou s., thomas d.n. & tison j.-l. 2011. sea ice contribution to the air-sea co2 exchange in the arctic and southern oceans. tellus series b chemical and physical meteorology 63, 823–830. schreiber u. 2004. pulse-amplitude-modulated (pam) fluorometry and saturation pulse method: an overview. in g.c. papageorgiou & govindjee (eds.): chlorophyll a fluorescence: a signature of photosynthesis. pp. 279–319. dordrecht: springer. suffrian k., schulz k.g., gutowska m.a., riebesell u. & bleich m. 2011. cellular ph measurements in emiliania huxleyi reveal pronounced membrane proton permeability. new phytologist 190, 595–608. thomas d.n. & dieckmann g.s. 2002. biogeochemistry of antarctic sea ice. in r.n. gibson et al. (eds.): oceanography and marine biology: an annual review. vol. 40. pp. 143–169. boca raton, fl: crc press. thomas d.n. & papadimitriou s. 2003. biogeochemistry of sea ice. in d.n. thomas & g.s. dieckmann (eds.): sea ice – an introduction to its physics, biology and geology. pp. 267–302. oxford: blackwell publishing. torstensson a., chierici m. & wulff a. 2012. the influence of increased temperature and carbon dioxide levels on the benthic/sea ice diatom navicula directa. polar biology 35, 205–214. trenerry l.j., mcminn a. & ryan k.g. 2002. in situ oxygen microelectrode measurements of bottom-ice algal production in mcmurdo sound, antarctica. polar biology 25, 72–80. trimborn s., brenneis t., sweet e. & rost b. 2013. sensitivity of antarctic phytoplankton species to ocean acidification: growth, carbon acquisition, and species interaction. limnology and oceanography 58, 997–1007. ugalde s., martin a., meiners k.m., mcminn a. & ryan k. g. 2014. extracellular organic carbon dynamics during a bottom-ice algal bloom (antarctica). aquatic microbial ecology 73, 195–210. young j.n., kranz s.a., goldman j.a.l., tortell p.d. & morel f.m.m. 2015. antarctic phytoplankton down-regulate their carbon-concentrating mechanisms under high co2 with no change in growth rates. marine ecology progress series 532, 13–28. 8 k. castrisios et al. abstract introduction materials and methods study area experimental set-up experiment 1: photophysiology experiment 2: carbonate chemistry ice algal species composition data analysis results and discussion photophysiology carbonate chemistry in situ fluorescence imaging conclusion acknowledgements disclosure statement funding references microclimate of the nest and egg water loss of the eider somateria mollissima and other waterfowl in spitsbergen h e r m a n n r a h n . john k r o g and fridtjof m e h l u m rahn. h . . krog, j . & mehlum, f. 1983: microclimate of the nest and egg water loss of the eider somareria mollissima and other waterfowl in spitsbergen. polar research i n s . 171-183. temperature gradients in the nest and within the egg. nest humidity as well as eggshell conductance and rate of egg water loss of the eider somareria mollissrma and other uaterfowl were studied at ny-alesund. spitsbergen (78%" latitude). these studies suggest a specific interrelationship between eggshell con ductance and maintenance of an appropriate temperature and humidity environment of the nest. resulting in an egg water loss rate which is optimal for hatching success. i n spite of low ambient temperatures of less than 3°c and very low absolute humidities of less than 4 torr (similar to those found in hot deserts). the nest's microclimate and rate of mater loss were similar t o those reported for nests and eggs in temperate climates. hermann rahn. department of physiolog)). srare uniuersiy of n e w york. buffalo, a'. y . 13214. l ' . s . a ; john krog. deparrmenr of zoophysiology, unruersiy of oslo. blindern. oslo 3 , norway; fridrlof mehlum. norwegian polar research institure. rolfstangueien 12, 1330 oslo lufrhaun. sorway: nouember i982 (accepred may 19831. r introduction while much has been written about the distri bution and nesting behavior of birds in the arctic, little if anything is known about the microclimate of nests of birds that colonize particularly the farthest reaches of the polar region. what are the egg temperatures and nest humidities that such birds can maintain during incubation under severe climatic conditions encountered in the high arctic area (79" north), and how d o these compare with nesting conditions in more southern latitudes. irving & krog (1956) examined nest air tem peratures of arctic birds in alaska (68" north) to see whether the eggs were exposed to lower or more variable temperatures than in temperate regions. using thermocouples affixed to the nest they determined the nest air temperature in seven incubating species and found that the median incubation temperature of 49 records was between 33°c and 3yc, and in 74% of the records, between 33°c and 37°c. these values were similar to those obtained by huggins (1941) in the cleveland, ohio, area (41" latitude); hug gins found a mean temperature among eggs of 37 species to be 34°c. s.d. 2.4. irving & krog con cluded that 'during the periods of incubation and brooding the growth of birds proceeds at well regulated temperatures in the changeable weather of temperate and arctic climates. the regulation of temperature during incubation and brooding is accomplished by the behavior of the parent birds'. in this study we examined the microclimate of the nest in three species of waterfowl nesting in kongsfjord o n spitsbergen (79" latitude). during the latter half of june (see map. fig. 1). the daily mean air temperatures were considerably lower than those in the alsaka study and did not exceed 4"c, while the mean ambient absolute humidity was below 4 torr (mm hg), equivalent to an air moisture content of 4 m g l i . not only did we examine the temperature gradients within the eggs as well as the nest and the absolute humidity of the nest's microclimate. but also the egg water loss and eggshell conductance. most of the infor mation was obtained for the eggs and nests of the eider (somateria ntollissima), with additional data from the nests of the barnacle goose (branfa leucopsis) and the long-tailed duck (clangula hyernalis) and the eggs of the pink-footed goose (anser brachyrhynchus) . 172 hermann rahn, john krog and fridtjof mehlum -7 j i location m a p p fig. i. location map. the nest. this was of sufficient length so that the incubating parent would not leave the nest when readings were made at various times of the day. temperatures were read from a kane-may tem perature recorder. as each nest was visited, the various leads were individually plugged into this hand-held digital read-out device. on one occa sion egg temperatures of eider eggs were meas ured by direct insertion of a thermistor into the egg at various levels. readings at the top, center, and bottom of the egg were made in succession within 30 seconds of the female leaving the nest. brood patch temperature. a small piece of styrofoam plastic was mounted on top of the egg to serve as insulation from the remainder of the egg. a small thermocouple was then mounted on top of the insulation to come in contact with the skin of the brood patch. the leads from this thermocouple were affixed with wax to the outside of the shell as shown in fig. 2. nest air temperature. these were recorded con tinuously in the nest of the long-tailed duck using a thermistor which was mounted as shown in fig. 2. body temperature. -female eiders were captured using a 4 m-long handle net on the nest. while one person held the body, the other opened the bill and inserted a wooden bit to lodge across the angle of the bill so that it stayed open. a small methods temperature measurements egg tempernture. copper-constantan thermo couples were secured at various levels in either fresh eider or chicken eggs. to prevent such eggs from turning in the nest, they were secured on a small board with epoxy resin as shown in fig. 2 . the thermocouple leads exiting beneath the board were buried and extended 10-15 m beyond fig. 2. schematic section through eider egg showing locations of thermocouples and their leads brought out through a hole in the wooden platform which serves to keep the egg in the upright position once placed in the nest. thermocouple mounted on a styrofoam insulation was used to measure the brood patch temperature. its leads were attached with wax to the outside of the egg. next to the egg is mounted a thermistor for air temperature recordings. on the right is shown the wooden bit in the angle of the eider's bill. a polyethylene tube (outside diameter 3 mm) is advanced through a hole in the bit down the esophagus a distance of 36cm to the proventriculus. the thermocouple initially retracted is then advanced 3 m m beyond the end of the tube for the temperature reading. nest microclimate of the eider 173 e g g humidity. the water vapor pressure in the eggs provides the pressure head for the flux of water vapor which leaves the egg during incu bation. this vapor pressure is essentially satu rated and thus can be estimated from the egg temperature using standard water vapor pressure-temperature tables. hole in this bit allowed a third person to advance a ( 3 m m o . d . ) polyethylene tube into the prov entriculus (see fig. 2). after placement a 0.9 mm thermocouple junction inside the tube was advanced 3 mm beyond the terminal end of the tube and the temperature read on the kane-may temperature recorder. the whole operation from the time of capture to the temperature read-out was accomplished in less than one minute. nest and ground temperatures. temperatures at the bottom of the down layer and a few cm below the down layer were measured with thermocouple junctions in eider nests from which the female had been flushed. the depth of the compressed down layer and the ground beneath the nests were also measured. ambient air temperatures. these were daily averages taken from the official log of the local weather station located with 0.5 km radius of the eider nests. humidity measurements nest humidity. egg diffusion hygrometers were prepared as previously described (rahn et al. 1977). briefly, chicken eggs were emptied, cleaned, dried, and filled with a desiccant, silica gel. they were then calibrated by exposure to a constant water vapor pressure in a sealed con tainer. the daily gain in water vapor was meas ured and provided the necessary calibration of the diffusive eggshell conductance expressed in mg hzo day-' torr-' (1 torr = 1 mm hg vapor pressure). once calibrated, the eggs were weighed just prior to insertion into the nest and again 2-4 days after removal from the nest. from the average daily weight gain in the nest and the eggshell conductance, the mean water vapor pres sure can then be calculated, since pn = &f;ih20/g~z0, where pn = the mean water vapor pressure in the nest, torr; =the mean daily weight gain of water, mg day-'; g = the shell conductance, mg day-' torr-'. the chicken egg hygrometers were readily accepted in all the nests. ambient humidity. the absolute ambient humidity was calculated from the mean air tem perature and the relative humidity values of the weather station records, and is also expressed in terms of the water vapor tension, torr. weight changes of eggs during incubation these were determined at various intervals using pesola scales. egg and shell dimensions initial egg mass. since eggs lose appreciable amounts of water during incubation, the air cells were displaced by water in order to establish the initial egg mass; this technique was recently vali dated (grant et a]. 1982). weight measurements were made on a torsion balance to within + 3 mg. initial egg density. this value was calculated from the egg dimensions provided by schonwetter (1960), as recently reported by rahn et al. (1982). surface area. this value was derived from the allometric relationship between surface area and egg mass (paganelli et al. 1974). length and width. these were measured using calipers as previously described (rahn et al. 1976). shell weight. after eggs were emptied the shell was dried, first in air and then for at least one day in a desiccator before weighing on a torsion balance within + 3 mg accuracy. shell thickness. this was measured to three significant figures with a ball point micrometer. twenty-one measurements from representative areas were taken and averaged for each egg. pore counts of shell shell fragments were boiled in a 2.5 koh solution to remove all proteinaceous material. they were then etched in concentrated nitric acid for several seconds, the time depending upon the thickness of the shell. the etching process enlarges the pores so that painting the inside of the shell with a water soluble dye will draw the solution to the 174 hermititi rahti, john krog utid fricirrof mvhlitrn outside rim of the pores t h e pores in each of twenty 1/4 cm' areas h e r e counted and averaged. and the total number per egg calculated on the basis ot its surface area the average coefficient of variation of the 20 pore counts for each egg i s about 2 0 7 egg rliell r o t i c i i ~ t m i c e this was measured according to the method of ar e t al. (1974). eggs were placed at constant room temperature in desiccators with silica gel. the daily weight loss was established and divided by the saturation water vapor pressure at that temperature to yield the eggshell conductance to water vapor expressed i n mg h:o day-' torr ~ ' _ results teniperatitres body temperature of ten female incubating eiders was determined at about 2400 on 2 july. the values ranged from 38.2 t o 395°c. with a mean value of 39.1"c. s.d. 0.4. t h e brood patch tem peratures had a mean value of 38.5"c in eiders and 37.7"c in the barnacle goose (table 1). the width of an eider egg is 5 cm (table 5 ) and the implanted thermocouples were situated 0.5 cm from the top, i n the center. and 0.5 cm above the t d d r 2 local temperatures in 12 eider nests. s . d . in parenthe5es. bottom of gravel-sand down layer below down distancc helow egg or below down. cm 3 . 3 (0.8) 4.1 (1.8) >lean temperature. "c 20.4 (3.8) 10.3 ( 3 . 3 ) bottom of the shell. from table 1 i t can be seen that a 7.6"c temperature difference was observed over a distance of about 4 c m . t h e thermocouple in the center of the egg registered a mean value of 33.6"c about halfway between the top and the bottom thermocouples, and indicates a linear temperature gradient over the extreme distance. it is of interest to note that by direct insertion of a thermistor into six eider eggs the mean top to bottom temperature difference was only 4.1"c. the implanted thermocouples in the barnacle goose egg showed a mean difference of 5.3"c. a t the bottom of the down layer, 3.3 cm below the bottom of the egg, the temperature had fallen to 20.4"c. in the gravel-sand substrate 4.4cm below the down, the temperature averaged 10.3"c (table 2 ) . t h e ambient mean daily air temper atures during the period average about 4°c. humidities the absolute humidities of the nest's microclimate tubk i. . \ . l e a s m m c n t of brood patch and egg temperatures h! implanted thermocouples ~n thc eggs of eider (between 25 june and j jul! and the barnacle goose ( h e r w e n 30 junc and 3 jul! i . egg ccmperatures here also ohtained in eider eggs h y direct insertion ot '4 thermistor into top. center. and bottom of egg ( 2 8 j u n c ) brood egg method of pdtch top centei bottom meawrement eijcr previously 29.7 implanted thcrmocouplcs 7 0.8 6 h insertion of 31 9 thermistor 11 ~ previousl) implanted so nests 1 1 i 6 barnacle sn. obserlation5 6 6 go<)% hlcan temp . "c 37 7 35.9 30.6 s . d . 0 7 11.7 1.2 ~ thcrmocouplss nest microclimate of the eider 175 t a h k 3. absolute humidity values in nest of eider, barnacle goose. and long-tailed duck as well as ambient absolute humidit! and temperature values. date absolute humidity nest ambient ambient renip. hyg. n o . (torr) (torr) ("c) eider 27-30 june ( 2 nests) 3c1 june-3 july 7 6 18.0 4.2 3.6 20.3 4 . 3 4.3 mean 1y.2 4.3 4.0 14-17 june 17-20 june 2&23 june 23-27 june 27-30 june barnacle goose (1 nest) 30 june-2 july 3 18.7 4.0 1 .4 6 20.6 3.7 1.9 1 14.1 4 . 2 1 7 5 16.0 4.0 1 . 1 9 16.9 4.2 3.6 2 17.6 3.3 4.3 mean 17.3 4 . 1 1 5 s d 2.2 0.2 i ? long-tailed +13* j u n e duck 13-16 june (1 nest) 1 6 2 0 june 1 10.9' 2 15.7 5 14.0 mean 14.9 3 i " 1.8' 3.8 2.0 3.8 1.7 3.8 1.9 * incubation had not started during this period. values omitted from mean. for the three species are shown in table 3, giving the date during which a particular egg hygrometer was in the nest. in the barnacle goose nest we have a continuous record of nest humidity over an 18-day period, with remarkably little change and maintaining an average value 13 torr higher than the absolute ambient humidity. during six days of integrated records of the eider nest the nest humidity was maintained 15 torr above the ambient humidity. t h e nest humidity of the long-tailed duck during seven days of recording was somewhat lower than for the first two species, maintaining an 11 torr difference above the ambient humidity. table 4. average weight losses of eggs during incubation weight loss of eggs the mean weight loss for eider eggs was 0.59 g/day. assuming this t o b e a n average throughout incubation, this would result in 25 days in a net loss of 14.8g or 14% of the initial egg mass of 103 g (table 5 ) . f o r the barnacle goose the daily weight loss of 0.57 g for 24.5 days of incubation would result in a net loss of 1 4 g , or 13% of the initial mass of 109 g. i n the long-tailed duck the average value after the initiation of incubation was 151 mg day-'. however, this mean rate dur ing the first 15 days does not reflect the progressive increase in the daily rate from 100 to 1 8 0 m g day-' during four successive weighings during this interval weight loss no. nests no. eggs (days) (mg.day-') se eider barnacle goose long-tailed duck 8 1 1 27 4 4 19 6 15 590 32 572 69 151 3 176 hermann rahn, john krog and fridtjof mehlum period, and thus does not provide a good basis for an overall estimate of incubation water loss. egg dimensions these are shown in table 5 and agree within 3% or less with the values for egg mass, length, width, shell mass, and shell thickness provided by schonwetter (1960). the indicated typical clutch size and incubation times are taken from johns gard (1978). shell conductance and pore dimensions the mean values for water vapor conductance of the shell, g , the pore length or shell thickness, l, and the number of pores in each egg are shown in table 6. since water vapor transport across the shell obeys fick's first law of diffusion, the shell conductance is proportional to the total pore area, a,. and inversely proportional t o the length of the pore, l. (paganelli 1980). substituting the measured values for g and l allows one to cal culate a, = 0.447 g.l (rahn et al. 1976; paga nelli 1980) as shown in table 6. compared with the surface area of the egg (table 5 ) , a, is very small; for example, in the eider it is equal to (3.7/10,700) or 0.03% of the egg's surface area. all gas exchange during incubation is limited to this small fraction of the shell's surface. when the total pore area, a,, is divided by the total number of pores, n , one obtains the average cross sectional area of the individual pores as well as the pore radius, assuming that all pores have uniform diameter throughout their length. the actual shapes of the pores for the eider, pink footed goose, and barnacle goose are drawn to scale in fig. 3. they were copied from the pore casts made by tyler (1964). according to tyler (1964) and board et al. (1977), examination by light and electron microscopy reveals that these pores are partially obstructed by the remains of the cuticle and organic spherules which fill the upper cup of the pores. this is shown diagra matically in the center of the lower row in fig. 3. to the left are three pore casts of the eider and to the right are the calculated dimensions. since this calculation is based on a functional performance, namely, the conductance, the derived dimensions are smaller than the actual pores becawe of the obstruction and therefore one must speak of an effective pore area and an fig. 3. pore casts reproduced from tyler (1964). 1. pink-footed goose, 2. barnacle goose, and 3. eider. in the lower row are shown from left to right three pore casts of eider, a diagram matic cross-section through pore showing the organic spherules which obstruct the pore cup according to tyler (1964) and board et al. (1977). on the right are the calculated effecfiue pore dimensions for eider eggs. see text. effectiue pore radius (paganelli 1980; board 1982). our shell conductance measurements of eider eggs were done on freshly laid eggs before incu bation had started. to our surprise these values were very much lower than one would have expected (ar & rahn 1978) and lower than those that h.r. had previously obtained in incubated eider eggs in alaska and canada. we believe that these low conductance values were due to the presence of cuticular covering plugging the pores which had not yet been removed by pro nest microclimate of the eider 177 longed contact with the brood patch. similar dif ferences in conductance value were observed between unincubated and incubated eggs of the long-tailed duck. for this reason the shell con ductance values for the eider listed in table 6 are based on the average value of nine eggs pre viously measured. as far as we know this is the first observation in non-passeriform eggs that the water vapor conductance will change after incu bation is initiated. that such changes occur in the small eggs of passeriform birds has been pre viously reported by carey (1979), hanka et al. (1979), and sotherland et al. (1980). discussion body temperatures our mean value of 39.1"c for the incubating eider is similar to the 'abdominal temperature of the sitting eider' of 39.6"c reported by rol'nik (1970). kossack (1947) reported a 'cloaca1 tem perature for incubating canada geese' of 40.9"c (n = 2) and caldwell & cornwell (1975) men tioned a 'deep body temperature' of 41°c for the mallard. egg temperatures outer surface measurements. by attaching tem perature recording devices to the outer surface of natural eggs during natural incubation large temperature differences have been recorded table 6. shell conductance, pore length (= shell thickness), pore number per egg, and calculated total pore area and individual pore dimensions. standard error in parentheses. conductance mg.day-'.torr-' (gi eider 21.6. pink-footed goose 29.5 barnacle goose 22.7 long-tailed duck 11.6 (0.8) (1.8) (0.4) measured pore length mm (l) 0.381 (0.007) 0.451 0.460 0.271 (0.004) (o.oa8) number of pores (n) calculated total pore area individual pores (ap) area radius mm2 mp2 mlc 14,266 16,277 11,927 9,373 (684) (544) (939) ~ ~ 3.7 260 9.1 6.0 368 10.8 4.1 394 11.2 1.4 149 6.9 * see text 178 herniann rahn, john krog and fridtjof mehlum between the top and bottom surfaces. both rol'nik (1970) and drent (1970) have reviewed the literature. for example. burke (1925) meas ured these differences daily in five nests of the chicken throughout the whole incubation period, while drent (1970) made similar observations in the herring gull (larus argentatus). in both species the top of the egg under the brood patch maintained remarkably stable temperatures between 39.2 and 39.5"c, while the bottom sur face of the eggshell gradually increased in tem perature during the incubation period from about 30 to 34°c in the chicken and from about 27 to 35°c in the herring gull. in the kittiwake (rissa tridactyla). the t o p of the egg maintains a fairly constant temperature of 38°c throughout most of the incubation period, while the nest's surface below the egg (not the bottom surface of the egg) was approximately 11°c lower (barrett 1980). temperature differences within the egg. a few of these have been reported in natural eggs during natural incubation and are given in table 7 includ ing o u r own observations. t h e egg width of each species is also given. allowing o n e to calculate the approximate temperature gradient within the egg, a"c/cm. as may be noted. these vary greatly and a r e not necessarily related to egg size but more likely reflect the particular stage of embryonic development. in our study the thermocouples were implanted in freshly laid eggs with no appreciable heat production of the embryo nor chorioallantoic circulation. such eggs might be expected to have the largest gradients of l°c/cm or more as shown in table 7. i n the other reported studies the age of t h e embryo, the degree of chorioallantoic development. and the possible disturbance of the normal metabolism and cir culation by implantation of t h e thermocouple are unknown quantities. such factors would influence not only the absolute temperature but also the temperature gradient within the egg. central and air cell egg temperatures. egg tem peratures frequently reported are assumed to be central egg temperatures. the average value reported by drent (1975) for 16 non-passeriform species is 35.8"c. s . d . 1.1. o n e approach is to record the air cell temperature, which does not interfere with the normal development of the embryo. caldwell & cornwell (1975) measured air cell temperatures in mallard eggs (anas playrhynchos) during natural incubation. during the early stages these temperatures were about 33 t o 34°c and during the last week of incubation averaged 38"c, s . d . 1.2, with a n overall average of 36.3"c. s . d . 2.5, for t h e whole incubation period. similar studies in t h e canada goose (branta canadensis) gave values of 38.5"c. s.d. 0.7 (kossack 1947) and 37.9"c, s.d. 1.1 (cooper 1978). t h e latter study also showed a gradual increase in air cell temperature as incubation pro ceeded as well as a marked circadian rhythm, with lowest temperature occurring between 0400 and 0500 and the highest value between 1400 and 1600 hours, with a mean difference of 3.0"c. table 7 . temperature differences within natural eggs during natural incubation. their egg width and calculated temperature gradients. a"c;cm. temperatures. "c egg width temp. grad. ref. t o p center bottom cm at/crn 37.3 33.6 29.7 5 . 1 1.5 30.6 5.1 1 .0 34.6 6.9 0.3 eider /somareria mollissimaj barnacle goose 35.9 /branta kitcopsis) laysan albatross 1 36.8 (diomrdea mmurabilisi royal tern '. 39.2 37.8 4.4 0.6 (srerna maxima) kittiwake 3 38.0 36.4 lrissa rridacfla) great egret 36.9 34.3 (cavmerodrur alhrcc) cattle egret 2 37.5 36.8 /buhu/rus ibis) 1 4.2 0.8 4 1 1.3 3.3 0.5 7 references: 1 . grant. g . tpers. comm.). 2. vleck et al. 1983. 3. barrett 1y80. nest microclimate of the eider 179 "c 39.1 38.5 37.3 33.6 29.7 20.4 10.3 fig. 4. composite of various temperatures measured to show the heat gradients in the eider's nest. a distance scale is on the left. nest air temperatures. this is the temperature found between the eggs. these were measured continuously over a 5-hour period in the nest of the long-tailed duck during the first week after clutch completion and varied between 33 and 34°c. as pointed out by drent (1970, 1975), nest air temperature of the herring gull increases gradually over the first ten days of incubation and during this time may actually exceed the central or air cell egg temperature. measurements of nest air temperatures for other waterfowl have been reported for anus acuta, 35.9"c (irving & krog 1956), for mergus serrutor, 36.9"c (barth 1949), and for the domestic goose. 33.4"c (koch & steinke 1944). lomholt (1976) measured the air temperature and relative humidity 'below the eggs' of eiders and reported a value between 27 and 29°c. which is close to our bottom values inside the egg, namely, 29.7"c (see fig. 4 and table 7). nest air values for other non-passeri form birds have been reported by drent (1975), and for 16 species these average 34.8"c, s.d. 1.3. overall temperature gradient. in fig. 4 we have combined our various temperature measurements for the nest and the egg of the eider. the scale on the left indicates the spatial arrangement and on the right the continuous temperature gradient. these nests were located on a moraine close to the bay and the daily average air temperature varied between 3 and 4°c. it is interesting to note that the temperature gradient of the egg, as pre viously noted, was approximately ls"c/cm, while the gradient across the 3.8 cm of down as well as across 4cm of soil was similar, namely, ca. 2 . pc/cm. when these temperatures are compared with those of other waterfowl nesting in more tem perate climates there are no essential differences, thus confirming the observations of irving & krog (1956) that the arctic environment does not com promise normal egg and nest temperatures in these species. as far as our egg temperatures are concerned, it is important to bear in mind that these represent the situation during the early stages of incubation. as the chorioallantoic cir culation becomes established, it will have a great effect on redistributing the heat more evenly throughout the egg, thus diminishing the large gradients seen in fig. 4. the chorioallantois begins to make contact with the inner shell mem brane about day 6 in the chicken and finally envelops the whole shell by day 12, that is, after only 60% of the incubation period has been com pleted. it is at that time that the rapid growth of the embryo begins to contribute to the heat bal ance of the egg. it is therefore not until the last quarter of the incubation that one would expect to see temperature gradients within the egg reach their minimal values. as we shall see. these are important considerations for predicting the mean temperatures of the egg, since they determine the water vapor pressure head responsible for the incubation water loss. nest humidity the rate of water loss from the egg is equal to the product of the shell conductance and the water vapor pressure difference between the egg and that of the nest air. the vapor pressure of the nest air is therefore an important factor in the regulation of water loss. since arctic climates have a very low absolute humidity or vapor pressure, it was of particular interest to see how nest humidity in the spitsbergen area compared with that of nests in more humid and temperate climates.in table 8 we have compared our aver age values with those obtained in the nests of other waterfowl nesting in temperate regions. 180 hermann rahn, john krog and fridtjof mehlum table 8. absolute nest humidities (torr) in nests of waterfowl measured with egg hygrometers. the values reported for lomholt (1976) and koch 8. steinke (1944) were calculated from their measurements of relative humidity and temperature of nest air. nest humidity (torr) no. obs. reference eider 19.2 2 (somateria mollissima) 21.0 lomholt (1976) barnacle goose 17.3 6 (branra leucopsisl long-tailed duck 14.9 2 (clangula hyemalrrj domestic goose (anser sp. 1 snow goose (anser caerulescens) greylag goose f a n s e r anser) egyptian goose faiopochen aegyptiacus) mallard duck ( a n a s platyrhynchos) 14.0 24.2 22.3 19.2 17.4 koch & steinke (1944) rahn et al. (1977) rahn et al. (1977) rahn et al. (1977) rahn et al. (1977) there appears to be no essential difference and this suggests that these arctic nests are so well insulated against the dissipation of water vapor through the nesting material and the protecting by 24.5 days of incubation (johnsgard 1978) pre dicts a total weight loss of 14g, or 13% of their initial mass of 109 g. feathers that values characteristic of temperate climates are maintained. relation between egg water loss, egg temperature and nest humidity to ensure a given incubation water loss of the egg water loss during incubation egg, the shell conductance must be exposed to a although the rate of water loss is now known for finite nest temperature and humidity. during more than 80 species (ar & rahn 1980). it development, the oxidation of solids and the for includes only one species of waterfowl, namely, mation of metabolic water will each contribute the eider. hagelund & norderhaug (1975) studto an appreciable increase in the relative water ied the weight loss of eiders in spitsbergen over content of the eggs unless it is removed by dif a period of 20 days. in seven broods (33 eggs), fusion through the pores. knowing the metabolic the average weight loss was 625 mg day-'. rate throughout incubation, one can calculate that extrapolated over their reported incubation to achieve a relative water content at the end of period of 24.3 days this represents 14.5% of their incubation equal to that of the fresh egg, about initial egg mass of 104.5 g. belopolski (1961) 15% of the initial egg mass must be lost as water. reported the weight loss of eleven eider eggs in recent measurements of the relative water con the barents sea area with an initial mass of 102 g. tent of precocial eggs have shown that indeed this over a 25-day incubation period these lost 16.6 g, value is the same (72%) for hatchlings and the an average daily weight loss of 660 mg day-'. fresh egg in spite of a water loss equal to about these values may be compared with our value of 15% of the initial egg mass. o n the basis of these 590mg day-' over a four-day period (table 4). observations ar & rahn (1980) have proposed assuming this to represent the average value over that a particular incubation water loss is man a 25-day period of incubation, their total loss datory for optimal hatching success. would be 14.8 g, or 14.3% of their initial mass of we may now consider the nest conditions pre 103g, very close to the average value reported requisite for incubating eggs losing the proper for birds in general (ar & rahn 1980). the baramount of water. the rate of egg water loss is a nacle goose eggs over a 19-day interval lost on physical phenomenon dependent on the escape the average 572 mg day-'. multiplying this value of water vapor by diffusion across the pores of nest microclimate of the eider 181 the shell. it can be described as follows (rahn et al. 19761: mh20 = gegg (pa pn)h2o (1) where mh,o = rate of water loss, mg day-', gegg = water vapor conductance of the shell, mg day-' torr-', pa = water vapor pressure in the egg, torr, and pn = water vapor pressure in the nest air surrounding the egg, torr. substituting into equation (1) the values for the eider, where mh10 =590mg day-' (table 4) and g,,= 21.6mg day-' torr-' (table 6), one obtains the water vapor pressure difference (pa pn) which must have existed between the egg and nest air and is equal to 27.3 torr. since we also know the vapor pressure of the eider nest, pn = 19.2 torr (table 3) we can add these two values (19.2 + 27.3) to obtain the water vapor pressure of 46.5 torr that must have existed in the egg, pa. the water vapor pressure in the air spaces of the membranes beneath the shell is essentially satu rated, and thus one obtains from this value the average temperature of the egg, which according to the vapor pressure-temperature tables is 36.8"c. similar calculations for the eggs of the barnacle goose predict a temperature of 35.2"c. both of these values are similar to the central or vapor pressure 5o ph20rtorr 7 4 0 10 20 30 y 40 fig. 5. simultaneous values of temperature and absolute humidity values found in the egg of the incubating eider, a , the nest air, n , and the ambient environment, 1. curve on the left is saturation water vapor pressure at various temperatures equivalent to 100% relative humidity. curves to the right are isopleths for relative humidity values of 80, 60, 40, and 20%. (for discussion see text.) air cell temperature of other waterfowl eggs dis cussed above as well as the average egg temper ature value for non-passeriform eggs in general, namely, 35.8"c (drent 1975). in fig. 5 are shown the water vapor tempera ture coordinates where the left hand curve rep resents saturation water vapor pressure (= dew point or 100% relative humidity). the other curves represent isopleths for relative humidity of 80, 60, 40, and 20%. point a represents the air space benetah the shell which is saturated at 46.5 torr at 363°c. point n represents the vapor pressure of the nest = 19.2 torr. this point was arbitrarily placed at a temperature of 34"c, an average value for nest air temperature (drent 1975). however, this point can be moved to the right or the left along the 19.2 vapor pressure isopleth when better values for nest air temper ature are eventually obtained. the exact location is of importance only if one wants to obtain a more reliable value for calculating the relative nest humidity. at present, this is shown at ca. 50%. for our purposes, the important difference is the vapor pressure difference between the egg and the nest (pa pn), where pa is determined by the egg temperature and pn by the nest con struction, feather cover, and brooding behavior of the parent. for a given value of (pa pn), the rate of water loss depends on the magnitude of the shell conductance, gegg. by rearranging equation ( l ) , (pa pn) = m h ~ o / g ~ ~ ~ as shown on the right ordinate of fig. 5. in the case of the eider, the required conductance is established in utero long before incubation begins by the for mation of 14,000 pores which have an average length of 370 pm and an effective radius of 9 pm (table 6). nest conductance water vapor released from the egg cannot accu mulate in the nest without raising its vapor pres sure. it must therefore escape by diffusion and/ or convection across the nest and feather barrier. in the steady state the rate of water vapor escape from the nest must equal the escape rate from the egg, assuming that additional release of water vapor from the brood patch is negligible. thus one can write an equation for water loss from the nest, where 182 hermann rahn. john krog and fridtjof mehlum where mhio =rate of water loss for each egg from the nest and is assumed t o be equal t o the rate of water loss from the egg. mg day-', g,,,, = the water vapor conductance of the nest, assumed to be by diffusion only. mg day-' torr-', pn = water vapor pressure of the nest, torr, and pi = water vapor pressure of the ambient environment, torr. the mean ambient vapor pressure. pi, was equal to 4.0 torr. substituting this value in equa tion (2) allows one to obtain the water vapor conductance of the nest per egg. g,,,, = 590/ (19.2 4.0) = 39 mg day-' torr-'. nearly twice the value of the egg conductance. o n the right ordinate of fig. 5 the bracket indicates the (pn pi) difference which is determined by the ratio of mh20/g,,,,. comparison of dry and moist climates in view of a prescribed incubation water loss it is of interest to compare the effects of a dry climate such as spitsbergen's with a moist climate of the tropics o n the development of nest and eggshell conductance. point i in fig. 6 described the ambient atmosphere, pi. at spitsbergen at yc, relative humidity 7096, and an absolute vapor pressure, torr 7 4 5 0 40 30 20 10 0 0 ' 0 20 30 'c 4 c fig. 6. comparison of the total water vapor pressure difference ( p a p , ) in dr!-cold a n d in moist-warm climates. (for discus sion 5ee text.) humidity of 4 torr. during t h e nesting season the ambient atmosphere of enewetak island in t h e pacific has a mean temperature of 28"c, relative humidity 80%, and a n absolute humidity of 24 torr (fig. 6) ( r a h n e t al. 1976). each value, 4 and 24 torr, represents the final sink for water vapor diffusion. assuming in each region a n egg temperature of 36°c equivalent to an egg vapor pressure of 44 torr, then t h e total pressure dif ference (pa pi) available for t h e dissipation of water vapor is (44 4) o r 40 torr in the dry climate of spitsbergen and (44 24) or 20 torr in the moist climate of enewetak as illustrated in fig. 6. in each case this pressure difference must b e divided between that acting across the eggshell and that acting across the nest-feather barrier, since pa pi = (pa pn) + (pn + pi). since the flux rate of water vapor is assumed t o be the same for the egg and the nest, equations (1) and (2) can be substituted and rearranged to yield p a p i 1 ~ 1 mhxj gqg gnes, and since 1/g = the resistance, r (3) -pa pi re,, + r,,,, m h : o thus for a given water loss rate in both climates, (re,, + r,,,,) is half as large (and g twice as large) in the moist climate as in the dry. this does not mean that the eggshell resistance in the dry climate is necessarily half as large (or geg, twice as large), since the particular value of the regg will also depend on t h e changes in r,,,, (equation ( 3 ) ) , and t h e ratio of reg, to r,,,, will vary with each species. however, it emphasizes that each climate imposes a finite total water vapor pressure difference. pa pi (pa deter mined by the egg temperature and pi by the climate), and that the adaptive shell resistance depends upon the nest resistance, as their sums must equal (pa p[)/&0 according t o equation (3). egg resistance in each species is determined by the number of pores, their length and cross sectional a r e a , while a given nest resistance is achieved by the nest construction and the brood ing behavior and attentiveness of the parent. acknowkdgemenrr. these studies were carried out in june and j u l y 1982 at the norwegian polar research institute at ny-alesund. svalbard. and were supported in part by the bell nest microclimate of the eider 183 fund and the distinguished professor fund of the state uni versity of new york at buffalo to hermann rahn. the authors take pleasure in acknowledging the help of many others who assisted in these studies, particularly 0ivind tsien. references a r , a , , paganelli, c. v . , reeves, r . b . , greene, d. g. & rahn, h. 1974: the avian egg: water vapor conductance, shell thickness and functional pore area. condor 76, 153 158. ar. a. & rahn, h . 1978: interdependence of gas conductance, incubation, length, and weight of the avian egg. pp. 227-236 in j. piiper (ed.) respiratory function in birds, adult and embryonic. springer verlag. ar, a . & rahn. h . 1980: water in the avian egg: overall budget of incubation. a m . zool. 20, 3 7 s 3 8 4 . barrett. r . t . 1980: temperature of kittiwake rissa tridacpla eggs and nest during incubation. ornis scandinauica 11, 50-59. barth, e . k. 1949: redetemperaturer og rugevaner. naturen (bergen) 73, 81-95. belopolski, l. 0. 1961: ecology of sea colony birds of the barents sea (transl. from russian edition, 19.57). israel prog. sci. tranrl., jerusalem. board, r . g . 1982: properties of avian egg shells and their adaptive value. biol. reu. 57, 1-28. board, r. g . . tullett, s . g . & perrott. h. r . 1977: an arbitrary classification of the pore systems in avian egg shells. j. zool. lond. 182, 251-26s. burke, e . 1925: a study of incubation. monr. agric. exp. sra. caldwell. p. j. & cornwell, g . w. 1975: incubation behavior and temperatures of the mallard duck. auk 92, 706731. carey, c. 1979: increase in conductance to water vapor during incubation in eggs of two avian species. j. exp. zool. 209, 181-186. cooper. j . a . 1978: the history and breeding biology of the canada geese of marshy point, manitoba. wildlife mono graphs no. 61, 1-87. drent, r. h . 1970: functional aspects of incubation in the herring gull. behauiour, suppl. 17. 1-132. drent, r . h . 1975: incubation. pp. 334-420 in farner. d . s . & king. j. r . (eds.): avian biology vol. 5 . academic press, n.y. grant, g . s . , paganelli, c. v.. pettit, t . n. & whittow, g. bull. 178, 1-44. c. 1982: determination of fresh egg mass during natural incubation. condor 84, 121-122. hagelund, k. & norderhaug, m. 1975: studies of population changes and breeding processes in a colony of eiders (somateria mollissima (l)) in svalbard. norsk polarinstitutt arbok 1973, 141-162. hanka, l. r . , packard, g . c . , sotherland. p. r . , taigen, t. l . , boardman, t. j . & packard, m. j . 1979: ontogenetic changes in water-vapor conductances of eggs of yellow headed blackbirds (xanthocephalus xanrhocephalus) . 1. exp. zool. 210, 1 8 s 1 8 8 . huggins, r . a . 1941: egg temperatures of wild birds under natural conditions. ecology 22, 148-157. irving, l. & krog, j . 1956: temperature during development of birds in arctic nests. physiol. zool. 29, 195-205. johnsgard, p. a . 1978: ducks, geese. and swans of the world. univ. nebraska press, lincoln, nebraska. 404 pp, koch, a . & steinke, l. 1944: uber temperatur and feuchtig keit bei natur und kunstbrut. arch. kleintierzucht 3 , 153 203. kossack, c . w. 1947: incubation temperatures of canada geese. j . wildlife manage. 11, 119-126. lomholt, j . p. 1976: relationship of weight loss to ambient humidity of bird eggs during incubation. j. comp. physiol. 105. 189-196. paganelli, c. v. 1980: the physics of gas exchange across the avian eggshell. a m . zool. 20, 329-338. paganelli, c. v . , olszowka, a . & ar, a . 1974: the avian egg: surface area, volume and density. condor 76, 319-325. rahn, h . , paganelli, c. v., nisbet, i . c. t. & whittow, g. c. 1976: regulation of incubation water loss in eggs of seven species o f terns. physiol. zool. 49, 245-259. rahn, h . , ackerman, r. a . & paganelli, c . v . 1977: humidity in the avian nest and egg water loss during incubation. phys iol. zool. 50, 269-283. rahn, h . , parisi. p. & paganelli, c. v. 1982: estimating the initial density of birds’ eggs. condor 84, 339-341. rol’nik, v. v. 1970: bird embryology (transl. from the russian edition, 1968). israel prog. sci. transl., jerusalem. schonwetter, m. 1960; handbuch der oologie. meise. w. (ed.). akademie verlag. berlin. sotherland, p. r . , packard, g . c. & taigen, t . l. 1980: an altitudinal cline in conductance of cliff swallow eggs to water vapor. auk 97, 177-185. tyler, c. 1964: a study of the egg shells of the anatidae. proc. zool. s o c . lond. 142, 547-583. vleck, c. m . , vleck, d . , rahn, h . & paganelli, c. v 1983: nest microclimate, water vapor conductance and water loss in heron and tern eggs. auk 100, 76-83. the role of weathering and pedological processes for the development of sorted circles on kvadehuksletta, svalbard a short report bernd etzelmuller and johan ludvig sollid etzelmiiller. b. & sollid, j . l. 1991: the role of weathering and pedological processes for the development of sorted circles on kvadehuksletta, svalbard a short report. polar research 9(2). 181-191. the presence of silt-rich, fine-grained material at the center of the well-developed sorted circles on kvadehuksletta, svalbard. is a precondition for their development. field work, laboratory work, and data from published studies indicate that the fine-grained material is a dissolution product of the dolomitic bedrock. the silt is accumulated in situ and by slope wash in terrain depressions. chemical weathering and other pedogenetic processes. such as the translocation of silt, are of great importance in arctic regions and can create the sedimentological prerequisitzs for cryogenetic processes, such as frost sorting and cryoturbation. thercfore, the bedrock composition and the composition of surficial material are considered to be important control factors for these processes. bernd etzelmiiller and johan ludvig sollid, department of physical geography, universiry of oslo. p . 0. box 1042 blindern, n-0316 oslo 3, norway ~ ' ' ~ p 0 ~ , 4 ~ \ ~ 5 ~ ' ' introduction sorted circles on kvadehuksletta. situated on the peninsula brgggerhalvoya, svalbard, are mainly developed in fossil fluvial and beach sediments. the circles appear nearly unique on svalbard because they are exceptionally well-developed and unusually large. they were first described in detail by miethe (1912). on kvadehuksletta (fig. 1) the circles form local networks, as shown in fig. 2. the dynamics of the well-developed circles on kvadehuksletta have been studied in detail by hallet and others (hallet & prestrud 1986; andersen 1988; hallet et al. 1988). patterned ground in general o n the north side of brogger halvoya has been studied in detail by vanvliet lanoe (1988). similar circles on svalbard have been reported from southern spitsbergen in the hornsund area (cf. jahn 1975). this report deals with the problem of the regional distribution of this type of patterned ground and the prerequisites for its development on kvadehuksletta. the genesis of silty fine grained material, found in the center of the circles, is therefore regarded to be of great import ance. on kvadehuksletta fine material is lacking in the unaltered recent beach sediments but is found in older beach sediments. it is suggested that special geological and hydrological factors may favour frost sorting processes and the dev elopment of patterned ground on kvadehuks letta. this is indicated by the lack of well-devel oped forms in other similar strand-flat areas on svalbard which were observed under a surveying project carried out by the department of physical geography, university of oslo, in collaboration with the norwegian polar research institute (sol lid et al. 1991). the fine material is believed to originate as a weathering product, mainly from the dissolution of dolomitic limestone. carbonate dissolution has been described as an important geomorphological agent in arctic regions (hellden 1974; salvigsen & elgersma 1985; akermann 1973) and is viewed as a major prerequisite for the development of the sorted circles on kvadehuksletta. this report is to be regarded as a summary of preliminary results from field and laboratory work carried out in 1987 and 1988 at the department of physical geography, university of oslo, in connection with detailed geomorphological and quaternary geological mapping of kvadehuks letta, scale 1 : 10000 (tolgensbakk & sollid 1987). as a part of this project the genesis of the fine grained material found in the sorted circles was studied by etzelmuller (1989) under the super vision of j. l. sollid. more substantial infor mation about granolumetric and mineralogical analysis of the soils, especially those associated with the sorted circles, will be presented in another report when further laboratory analyses 182 b . etzelmiiller & j. l . sollid k o e s f m i d e u i .** i<... :.<x,f " o c . c l u l . io.lto c i k c i _.<i .u 1 fig. i . kvadehuksletta. located on the peninsula br0ggerhalvoya on the south side of kongsfjorden. the highest marine limit is about 80 m a.s.1. only the most pronounced beach terraces and well-developed sortcd circles are shown (based on tolgensbakk & sollid 1987). are completed and all data from previous field work have been processed. setting kvadehuksletta is a strand-flat area o n the north western point of b r ~ g g e r h a l v ~ y a , western spits bergrn (79"n 1 7 " e ) (fig. 1 ) . t h e bedrock of the area consists mainly of permo-carboniferous dolomite and minor areas of younger clastic sedi ments (orvin 1934: challinor 1967). the climate is high arctic with a marine influ ence. ny-alesund, about 10 km southeast of kva dehuksletta, has an annual mean air temperature of -6.1"c and mean precipitation of 373 mm. o n kvadehuksletta precipitation is assumed to be higher and the summer temperature slightly lower due to the location of ny-alesund in a fjordbasin. the thickness of the permafrost in the area is estimated to be about 200 m based on mcasurc ments carried o u t in front of the glacier austre brsggerhreen, about 1 0 k m south of kvade huksletta ( l i e s t d 1977). a complex of raised beach ridges covers most of the strand-flat a r e a (fig. 1). t h e best preserved ridges are located at levels below the shoreline a t 45 m , dated to late weichsel (about 13.5 ka) by formann et al. (1987). large beach ridges a r e , however, found up to a level of 74 m . according to formann & miller (1984) the uppermost beach ridges could be of pre-weichselian age (130 290 ka). they could suggest an ice-free kvade huksletta i n the weichsel. while most recently mangerud et al. (in press) propose a large weich selian ice sheet, reaching to the edge of the con tinental slope in the west. t h e latter does not necessarily imply that the beach ridges a r e of postglacial age. marine or glacial deposits can survive a glaciation under cold-based ice nearly undisturbed, as reported for recent forms from storsya, svalbard (jonnson 1983) or supposed for fossil forms in the southeastern regions of norway (sollid & sorbel 1984). geomorphologically, t h e complex of beach ridges could be divided into two areas, o n e below and one above 45 m a.s.1. t h e thickness of marine sediments varies by several metres around the the role of weathering and pedological processes on kvadehuksletta. svalbard 183 fig. 2. network of well-developed sorted circles on kvadehuksletta, developed in a moist terrain depression. the photo was taken from helicopter (j.l. sollid 1985). the two parallel stripes across a circle at left-center can be used as a scalc; the distance bctwcen these stripes is about two metres. beach ridges and locally t o almost zero in some interridge areas. h e r e weathered bedrock, flu vially reworked material. and patches of wet. richly vegetated tundra are found. t h e litho logical composition of the marine and fluvial sedi ments on kvadehuksletta reflect the bedrock geology of t h e area, with a dominance of car bonates. samples of pebbles from the recent beach sediments showed a content of about 80% dolomitic limestone and about 5 % other car bonates; the remaining 15% were sandstones, conglomerates and metamorphic pebbles. n o significant difference in the lithological com position between recent and fossil beach sedi ments was found. the hydrological regime of kvadehuksletta is controlled by the beach ridges and permafrost. small ponds fed by snow and permafrost melt water and by surface runoff a r e formed in terrain depressions behind t h e ridges. in spite of the relatively high precipitation, the cryogenetic undisturbed soils developed on the beach ridges a r e classified as being within the polar desert z o n e (tedrow 1977; ugolini 1986). the arid soil regime is mainly controlled by sedi mentological factors, such as the dominance of coarse-grained beach sediments with a thick active layer, which cause good drainage conditions. field and laboratory work the fieldwork for this report was carried o u t during the summers of 1987 and 1988. soil sam pling and detailed geomorphological and soil mapping were carried out along special profile lines (fig. 1). analysis of the rocktype composition of beach sediments was performed by counting 150 to 200 pebbles of the 8-16 m m fraction. grain size analy sis was done by wet and dry sieving. the fraction smaller than 63 p was analysed by a sedigraph 5000 d. mineralogical analyses were carried u t with a phillips pw 1729 x-ray diffractor with a cucy-lamp ( y = 1.54060 a). t h e fraction <63 184 b . etzelmuller & j . l . sollid s e c t i o n 1 a 0 c c r n i i i fig. 3. section through a typical well-developed sorted circle i n moist terrain depression. overlain by beach sediments a . domain (gravelly silt). b . circle border (rounded to subrounded bcach sediments, no fines). c. intercircle area (rounded to angular gravelly beach sediments). note the distinct border hetwecn domain and border. and border and inter-circle 0 5 0 100 i50 2 0 0 2 5 0 3 0 0 area. was used for a randomly-oriented bulk sample. the clay fraction ( < 2 w ) was separated by sedi mentation methods. at this stage an oriented sample was prepared and treated by standard clay mineral analysis techniques. regional distribution pattern sorted circlcs the stone borders outlining the sorted circles have a maximum height of about socm, with average heights of 20 to 3 0 c m . t h e material in the stone borders consists mainly of stones with a diameter of up to a few centimetres. t h e gravel in the borders reflects the surficial material where the circles a r e found. t h e central areas of the circles are dominated by silty fines. t h e fine domain is limited sharply by the gravel border. the limit extends vertically downwards pre sumably to the permafrost table. t h e same ver tical pattern was observed between the circle borders and the inter-circle area (cf. fig. 3 ) sug gesting some kind of vertical movement. t h e fine domain constitutes a plug under the centre of the borders. locally, material rich in silt was also found under the circle borders. as has also been described by jahn (1975) from the hornsund region. detailed geomorphological mapping shows that the well-developed networks of sorted circles (fig. 2) are concentrated around terrain depres sions where the water supply is relatively good. especially surrounding ponds and between beach ridges (fig. 1). these forms are found both in marine beach sediments and in fossil fluvial material. t h e age of the deposits does not seem to govern the pattern of distribution significantly. the circles a r e abundant and well-developed both in the youngest beach sediments and close t o the marine limit. however, areas with a network of sorted circles. as shown in fig. 2, are found mainly behind the 2 8 m ridge (tolgensbakk jt sollid 1987) which is dated t o about 10 ka (formann et al. 1987). this distribution pattern is d u e t o topographical and hydrological factors. single sorted circles a r e found over the entire strandflat area in various degrees of development. they are even found o n dry areas and in dolomitic weathering material in terrain depressions where surficial material thickness is small and water supply is present. t h e borders of these circles are built up of angular stones from bedrock weath ering debris. cryogenetic undisturbed soils the well-drained soils developed on the beach ridges are described in previous works (formann & miller 1984; mann e t al. 1986: sletten 1988). a major feature of these soils is a 15 t o 40 cm thick silt accumulation horizon (b,) which underlies an a-horizon showing extensive dissolution signs on pebbles (fig. 4). in and beneath the silt horizon secondary carbonate precipitation is found on the bottom side of t h e gravel. t h e chemistry and kinetics of the solution and precipitation of car bonates in these soils is described by sletten (1988). soil morphology and soil water chemistry indicate that this pedogenetic silt is mainly a resid ual of the dissolution of dolomitic gravel. the role of weathering and pedological processes on kuadehuksletta, sualbard 185 cm i p r o f i l e c : s o i l c a t e n a i1 ill iv v v i v i i ,.c' : s e 7 0 c n w 5 0 4 0 3 0 2 0 x 1 0 2 rn 0 2 0 0 4 0 0 600 800 1000 1 2 0 0 1400 1600 1800 2 0 0 0 2 2 0 0 2400 m e t e r s tiorisonla1 i v e r l l c a l s c a l e 1 1 5 m o i s t t e r r a i n d e p r e s s i o n s b e a c h s e d i m e n t s , d r a i n e d fig. 4. soil catena along profile line c-c' (cf. fig. 2). dp = desert pavement. a = horizon with obvious signs of carbonate dissolution (angular to subangular pebbles). b, = silt accumulation horizon (notation according to formann & miller (1984)). a / b , = horizon which shows beginning of silt translocation (siltcaps on pebbles). b/c = transition between silty b-horizon and parent material. g = water-saturated horizon (gleyic). 0 = organic horizon. (g) = temporally water saturated. the silt is translocated down through the soil column by percolating pore water and enriched in a silt horizon (formann & miller 1984). the translocation of fines is described by tedrow (1977) and ugolini (1986) as an important pedo logical process in well-drained polar soils, and reported from other areas, for example in mor ainic material in arctic canada (locke 1986) and in polar soils of antarctica (campbell & claridge 1987). formann & miller (1984) attempted t o use the degree of silt accumulation in the soils developed on the beach ridges as a relative dating tool for the marine deposits. in the youngest beach ridges, silt is mainly accumulated as silt caps on pebbles, while on older beach ridges the pebbles are totally imbedded in the silty soil matrix (fig. 4). the border between the two typical morphological features is the 45 m beach ridge. silt-rich horizons are lacking on the recent beach ridges between kvadehuken and kongs fjordneset. there are no signs of silt accumu lation, even by eolian or by pedogenetic processes. silt rich soils were observed in wet inter-ridge depressions, found outside the well-developed sorted circle areas. in these areas hydromorph soils have formed, with a gravelly 0and a horizon and a silty gleyic b-horizon saturated with water (fig. 4). transitions between cryogenetic undisturbed soils and sorted circles transitions between silt horizons and sorted circles are observed especially on the slopes of the beach ridges and in wet depressions. it is obvious that silty hydromorphic soils dominate in areas saturated by water, while sorted circles are formed in areas not constantly saturated by water but having a good water supply. this confirms observations by e.g. jahn (1975) in the hornsund region and by van vliet-lanoe (1988) along the northern coast of brbggerhalvoya. transitions between pedogenetic silt horizons and poorly developed sorted circles on the top of beach ridges have been observed locally. several excavations show that the b,-horizon locally reaches the surface, showing an early phase of development of sorted circles, even on dry areas as represented by the top of the beach ridges. transitions between horizontal silt horizons and mudboils o r 186 % 100 8 0 60 4 0 2 0 b . etzelmiiller & j . l . sollid a (gravel: 82.6%) b (gravel: 93.4%) c (gravel: 36.8%) + d (gravel: 31.82) 0 9 8 7 6 6 4 3 2 1 0 -1 phi fig. 5 . grain size distribution from silt-rich fines. soils sampled from the fine-grained center of sorted circles and from nearby areas. gravel was removed from the samples; the amount of gravel removed is given in brackets. a = silt accumulation horizon of soil developed on 36-m beach ridge. b = domain from section 1. c = domain from circle developed in weathering material. d = silt accumulation in undisturbed hydromorph soils ( 3 3 m a.s.1.). poorly-developed sorted circles observed on the slopes of beach ridges seem to be the result of slope-wash and translocation of silt by percolating pore water. such subsurface drainage is confirmed by observations referred in van wet-lanoe (1988) where these features can occur in zones with drainage concentration. subsurface drainage down the slopes of the beach ridges on kvade huksletta can concentrate on the permafrost table, especially in late spring and early summer. some results from soil sampling and analysis most work was carried out on the material rich in silt, sampled in soils from the fine-grained centre of sorted circles and from adjectant areas. as one of the aims of this work was to find evidence of the origin of fines in the circles, the samples were divided into silt collected from sorted circle sites and silt collected from other sites for cornparism. the first group was sub divided into fines from circles developed directly on beach terraces and from circles developed in moist depressions between terraces. the most striking feature is that the pedo genetic silt found in t h e silt horizons of the cry ogenetic undisturbed soils and the silty material in the sorted circles located nearby do not show any signficant difference, either in grain size dis tribution or in mineral composition. the fines here consist mainly of medium-coarse to coarse silt with a relatively small amount of fine and medium sand and clay (fig. 5 ) . mineralogical analysis of the fines shows that the silt is mainly composed of dolomite and quartz, with a varying amount of feldspar and mica. the quantitative distribution of the main minerals in the silt is found to be nearly the same as for the local unweathered dolomitic bedrock, with slightly higher values for quartz due to the dissolution of carbonates (figs. 6 and 7). the silt in sorted circles developed directly from weath ering material does not show any significant min eralogical difference to unweathered bedrock (fig. 6). feldspar and mica are therefore inherited from sandstones and conglomerates found in the surficial material. fines in sorted circles developed in moist depressions show small variations in grain size distribution and mineral compositions of the silt and clay fraction over the entire study area. almost the same values of these parameters, which are close to those of unweathered bedrock, have been measured both in forms nearby the recent coast line and nearby the highest marine limit, about 80 m a.s.1. the diffraction pattern of the silts directly con nected to beach terraces indicates an increase of quartz, feldspar and mica content relative to dolomite with the age of the beach terraces, both the role of weathering and pedological processes on kvadehuksletta, svalbard 187 10 5 0 q + m 3,34 i ' h d 2 , 8 9 40 35 0 0 c -30 2 x a 2 5 $ 0 20 15 10 f 0 l a i i i 1 i i i i 1 i i l l ' i i 1 " i r " i * * 1 h i i i i i 0 45 40 35 30 25 2 0 15 10 5 d e g r e e 2 8 fig. 6. x-ray diffraction pattern of fines from soil horizons and sorted circles. samples a t o e, pulver sample (<63 p). sample f, oriented sample of clay fraction, untreated. a = dolomitic bedrock. b = domain from circle developed in weathering material. c = domain from section 1 cf. fig. 3. d = silt accumulation in hydromorph soil (33 m a.s.1.). e = silt accumulation horizon of soil developed on 36-m-beach ridge. f = same as e, but fraction less than 2 p. labels of the peaks: m = mica, k/c = kaolinite and chlorite, q = quartz, f =feldspars, ca = calcite, d = dolomite. 188 b. etzelmiiller & j . l . sollid 100 80 20 n fig. 7. relative intensities of randomly oriented bulk saniples " 45 rn beach ridge (fraction < 63 p) of the b,-horizon of undisturbed soils developed on thc main beach ridges on kvadehuksletta. the relative intensities are expressed in percentage of the sum the intensities of the shown minerals. 28 rn beach ridge 36 rn beach ridge 49 ,,,beach we feldspars 1 mica 11 kaolinitdchbrite i..! in the randomly oriented bulk samples (fig. 7) and in the oriented samples of the clay fraction. the amount of clay minerals is almost negligible in the late weichselian and holocene areas of kvadehuksletta, excepting some mica, kaolinite and chlorite inherited from bedrock. in this frac tion dolomite and quartz dominate, with a higher quartz content relative to dolomite. the relative amount of clay minerals and feldspar seems to increase in the silt developed on older beach terraces above 45 m a.s.1. a possible time depen dence of the mineralogical contents of the fines will be discussed in a later paper. to test the hypothesis of the silt mainly being a residue of carbonate dissolution, a dissolution test was carried out. here crushed dolomite rock fragments and pebbles from beach sediments (fraction 4-8cm) were treated with a light acid (ph 2.5) over a period of one week. after this period a considerable amount of residue was pro duced, which could be analysed by grain size and mineral distribution. knowing that the chemical conditions of the test did not represent natural conditions. the results of the analyses showed, however. similar values as those obtained from field samples, with a low clay content and the mode of the distribution in the medium to coarse silt fraction. the test indicates that the dissolution of the dolomitic bedrock o n kvadehuksletta pref erably produces a residue rich in medium to coarse silt. discussion goldthwait (1976) defined the sedimentological prerequisites for the development of frost-sorted patterned ground as primarily being the existence of poorly sorted, heterogenous sediments with a relatively high amount of silt and clay (more than 15%). according to washburn (1980) the amount of silt and clay is important for effective frost heave and frost sorting. most sorted forms described in different studies are observed in areas dominated by till; till normally satisfies the above-mentioned granolumetric conditions (e.g. ballentyne & matthews 1982; harris & cook 1988; karte 1979). fines are originally lacking in the marine beach deposits on kvadehuksletta. the accumulation of silts in areas where networks of sorted circles are abundant can be explained as being an older sediment layer, the result of secondary trans location processes by slope wash or sub-surface drainage, or the result of in situ weathering. the silts can be of marine origin, deposited before the pleistocene beach sediments. a stratigraphic silt rich layer beneath the beach sediments was, how t h e role of weathering and pedological processes oti kvadehuksletta, svalbard 189 ever, not verified elsewhere in the study area. sections along the rivers show the beach sedi ments resting directly o n the bedrock. t h e terrain depressions behind the fossil beach ridges rep resent a similar coastal environment as observed around the recent beach ridges, with the existence of lagoon lakes behind a beach berm. there, one would, theoretically. expect to find fluvial or lacustrine sedimentation of silt rich fines. if this is the case, o n e would expect stratigraphic silt layers in or o n t o p of beach sediments with a relative high degree of sorting. this was not observed in the field. hand-augering o n several sites shows that the silts a r e accumulated as pore fills in the gravelly surficial material, resulting in low sorting values of the material. drilling in the present lagoon lakes would give a better answer to the last proposed theory. t h e above observations indicate, however, that the silt accumulation is due to other processes than marine or lacustrine sedimentation. field observations and laboratory analysis indi cate that the silt in the centres of the sorted circles is of the same origin as the pedogenetic silt described in the soils developed on the beach ridges. t h e fines in the domains of the sorted circles a r e therefore also inferred t o b e originally a weathering product d u e t o chemical dissolution of the dolomitic bedrock and dolomitic gravel in the surficial material. t h e feldspar and mica content indicates, however, that frost shattering occurs as well as the proposed dissolution of car bonates, since these minerals are considered t o be inherited from the clastic pebbles in the surficial material. formann & miller (1984) assume, how ever, that chemical dissolution produces more silt-sized material o n kvadehuksletta. that pro cesses other than frost weathering can b e of importance in cold climates, a t least in carbonate sedimentary rocks, is confirmed by the results of laboratory studies obtained by fahey & dagesse (1984), who showed that adsorption-related pro cesses during oscillations of relative humidity and temperature can contribute t o particle disin tegration. o n the basis of these observations the fines are believed t o accumulate both by in situ weathering and by slopewash with later sedimentation in the coarse beach and fossil fluvial sediments in terrain depressions. t h e grain size distribution of the surficial material then changes from a relatively well-sorted gravelly sediment to a poorly sorted material with a bimodal grain size distribution after the accumulation of fines. this distribution matches the sedimentological prerequisite des cribed by goldthwait (1976) for the development of frost-sorted patterned ground. when the silt content passes a certain limit, frost action can progress. this limit is estimated t o be between 1&12% silt and clay for the beach sediments, and is evidently reached when all macro pores in the gravelly surficial material are filled with fines. the water capacity then increases rapidly and favours further frost processes. the grain-size distribution of the silt rich material of the circle domain and the lower silt limit proposed here correspond with observations from other areas (cf. ballentyne & matthcws 1982: goldthwait 1976; harris & cook 1988; nicholson 1976; washburn 1988). common for these observations is the presence of silt-rich fines in the circle domain, confirming the import ance of the presence of silt-rich fines for the dynamic of frost processes (washburn 1980). in more or less constantly moist areas, the lithological composition of the bedrock and the surficial material play an important role. both for frost processes and for the genesis of fines. t h e hydrological conditions not only govern the frost activity in the ground but also the production of fine-grained material. i n terrain depression. in addition to the proposed translocation of silt, there will be a constant water supply from reactive snow and permafrost meltwater, at least in the late spring. this favours carbonate dissolution and in situ production of silty residue from the dolomitic limestone. this process will continue until a supposed upper limit of silt accumulation is reached. based on data from published studies, the fea tures described above, and observations from sec tions dug in undisturbed soils and certain sorted circles in different stages of development, the following development pattern of sorted circles on kvadehuksletta is suggested (fig. 8). t h e sorted circles develop from a stage where gravelly sediments overlie fine-grained material. t h e fines are originally produced by in situ weathering and accumulated either by soil processes in a silt hori zon or by slope wash and sedimentation of fines in terrain depressions. this results in a higher frost susceptibility in part of the soil and leads to vertical and lateral mass displacement or dif ferential frost heaving. a d o m e of fines is formed, which migrates upwards, eventually reaching the surface ~ producing patterned ground (sollid & sorbel 1988). t h e concept of vertical and lateral 190 b . etzelmuller & j . l . sollid i ' circles starts after a certain limit of silt accumulation has been passed. t h e amount of silt accumulated in the surficial material is therefore one of the main factors that influences the dev elopment and t h e pattern of distribution of sorted 1 circles on kvadehuksletta. ri i 111 fir. 8 stages n f the derclopment of sorted circle\ (from sollid & sorhel 1988. modified). 1 = initial stage of 5111 accumulation and lcrtical torting. i i = l'crtical and lateral mass dkplacc mcnt. ill = earl) stage o f the dcvclopment o f sorted circles. forming a mud boil uhtch reaches the surface. iv = later 5tage. with dcvcloprnent of circle border\. mass displacement in periglacial soils was dis cussed by g r i p p & simon (1934) and later used t o explain the development pattern of sorted circles and other forms of patterned ground (cf. jahn 1975: van vliet-lanoe 1988; washburn 1988). recently, convective processes d u e to a density gradient in the soil a r e suggested to be a main factor in the development of sorted circles (and ersen 1988: hallet & prestrud 1986; hallet e t al. 1988). it is supposed that t h e sorted circles a r e initially formed in a relatively short period of time. they probably then reach a mature state with little further change in their pattern. this would explain the small differences of t h e fine-grained material in the circles covering the study area. it is further suggested that the development of the conclusions o n kvadehuksletta t h e development of frost sorted patterned ground is directly related to the accumulation of fines, which seems to be a residue of the weathering of bedrock and autochtone dolomitic surficial material. this study suggests that chemical dissolution can be an important factor. even for the dynamics of cryogenetic pro cesses. together with o t h e r geomorphological processes, such as slope washing, weathering is a prerequisite and source for later frost sorting and mass displacements in the soils of kvadehuks letta. t h e dolomitic limestone is therefore sup posed to be a major controlling factor for frost processes o n kvadehuksletta; this emphasizes the importance of bedrock petrography and sediment lithology for the distribution pattern of patterned ground o n svalbard. r\c.kfiok,/edjie,~ierirs. b. hallct reviewed thc paper and gave constructive comments. the laboratory analyses wcrc carried nut at the department of geology. university of oslo. tinder the guidance of p. aagaard and t. winjc. the norwegian polar research imtitute contributed logistic and financial support. the kings bay kull comp. a/s allowcd us to use the cottage -'geopol" on kvadehuksletta during thc summer field work. the authors thank the rnentioncd persons and institutions. references andenon. s. p. 1988: upfreezing in sorted circles. westcrn spitshcrgen. pp. w 7 1 in senneset, k . ( e d . ) : proceedings. fifth internurional conference on perniufrosr. the norwegian committce on permafrost, the norwegian institute of tech nology. trondheim. ballcntyne. c. k . & matthews. j . a. 1982: the dcvelopnient of sorted circlcs on recently deglaciated terrain, jotunheinmen, norway. arctic and alpitie research 14 ( 4 ) , 341-351. campbell, 1. b . & claridge, g . g . c. 1984: antarctica: soils. weathcring processes and environment. developnierits in soil srience 16. elsevier. amsterdam. 368 pp. challinor. a. 1967: the structure of brtiggerhalvoya. spits bergen. geoologitr magazine 104, 322-3.36. etzelmiiller. b. 1989: finkornet materide, ders dannelse og b e y d n i n g for frosrprosesser p d kvadeairkslena. suolbard. l.ipubl. cand. scient. thesis in geomorphology. department of physical geography. university of oslo. 113 pp. + appen dix. the role of weathering and pedological processes on kvadehuksletta, soalbard 191 fahey. b . s. & dagcsse, d . f. 1984: a n experimental study on the effect of hcmidity and temperature variations on the granular disintegration of argillaceous carbonate rocks in cold climates. arctic and a l p i n e research 1 6 , 291-298. formann, s . & miller, g. h. 1984: time-dependent soil mor phologics and pedogenic processes on raised beaches, breg gerhalvbya. spitsbergcn. svalbard archipelago. arctic and alpine research, 381-394. formann, s . , mann. d. h. & miller, g . h . 1987: late weich selim a n d holocene relative sea level history of brdgger halveya. spitsbergen. quaternary research 27. 41-50. goldthwait, r. p. 1976: frost sorted patterned ground: a review. quaternary research 6. 27-35. gripp, k . & simon, w. 1934: die experimentelle darstellung des brodelbodens. nanrrwiss. 22. %lo. hallet. b. & prestrud, s . 1986: dynamics of periglacial sorted circles in western spitsbergen. quaternary research 26, 81 99. hallct. 8.. anderson, s . p.. stubbs. c. w. & gregory, e. c. 1988: surface soil displacements in sorted circles, western spitsbergen. pp. 77&775 in senneset. k. (ed.): proceedings, fifth international conference on permafrost. the norwegian committee on permafrost, the norwegian institute of tech nology, trondheim. harris, c. & cook. j. d . 1988: micromorphology and micro fabrics of sorted circles, jotunheimen. southern norway. pp. 776783 in senneset, k. (ed.): proceedings. fifth inter national confrrence o n permafrost. the norwegian com mittec on permafrost, the norwegian institute of technology, trond heim. helldin, u. 1974: karst. en studie av artfjlllets karstomrade sam jamforande korrosionsanalyser f r i n vastspetsbcrgen och tjekoslovakien. meddelanden f r i n l u n d s uniuersitets geo grajisku institution a ohattdlitlgpar l x x i i . 192 pp. jahn. a. 1975: problems of theperiglacial zone. polish scientific publishers. warsawa. 220 pp. jonnson. s . 1983: on the geomorphology and past glaciation of stordya, svalbard. geografisku annaler. ser. a 65 (1-2). 1-17. karte, j . 1979: raumliche abgrenzung und rcgionalc dif fercnzierung des periglaziars. bochumer geographische arbeiteri 35. 21 i pp. liestel, 0. 1977: pingos. springs and permafrost in spitsbergcn. norsk polarinrtirutt a r b o k 1976, 7-25. locke. w. w. 1986: fine particle translocation in soils devel oped on glacial deposits, southern baffin island, n.w.t., canada. arctic and a l p i n e research 18. 33-43. mangerud. j . , bolstad, m.. elgersma, a , . helliksen. d.. land vik, j . y . , lbnne. i . , lyche, a . k.. salvigsen. o . , sandahl. t. & svendsen, j . i . in press: thc last glacial maximum on western svalbard. quaternary research. mann. d. h . . sletten, r . s . & ugolini. f. c. 1986: soil development at kongsfjorden, spitsbergen. polar research 4 , 1-16. miete. a. 1912: uber karreebodenformen auf spitzbergen. zeitschrift d e r gesellschaft f u r e r d k u n d e z u berlin (vol. 4, 1 6 1 9 ) . 241-244. nicholson, f. h. 1976: patterned ground formation and description as suggested by low arctic and subarctic examples. arctic and a l p i n e research 8 . 329-342. orvin. a. k. 1934: geology of the kings bay region. spits hergen. skrifter o m svalbard of lshauer 57. 190 pp salvigsen. 0. & elgersma, a. 1985: large-scale karst features and open taliks at varderborgslettaouter isfjorden, svalbard. polar research 3 . 145-155. sletten, r. s . 1988: the formation of pedogenetic carbonates on svalbard: the influence of cold temperatures and freezing. pp. 467-472 in scnneset, k. (ed.): proceedings, fifth infer national conference on permafrost. the norwegian com mitteeon permafrost. the norwegian institute oftechnology. trondheim. sollid j . l. & sdrbel. l. 1984: distribution and genesis of moraines in central norway. pp. 63-67 in kdnigsson. l.-k. (cd.): ten years of nordic till research. striae 20. uppsala. sollid. j l . & serbel, l. 1988: the area of kvadehuksletta and ny-alcsund. pp. 2(&26 in orheim. a . & sollid. j . l. (eds.): svalbard excursion guide. meddelelser fra grografisk insri tuti, uio. naturgeografisk serie. rapport n r . 8. oslo. sollid, j . l., serbcl, l. & bdeglrd, r. 1091: sualbard coast oideo s u r v e y . department of physical geography. university of oslo. and norwegian polar rcscarch institute. tedrow. j . c. f. 1977: soils of the p o l a r landscape. new brunswick. 638 pp. tolgensbakk, .i. & sollid. j . i . 1987: kuadehukslerta. gemor fologi og kuarruergeologi 1:10000. geografisk institutt. univ ersitet i oslo. ugolini. f. c. 1986: pedogenclic zonation in the well-drained soil of the arctic regions. quafernary resrarrh 26. 10&120. van vliet-lanoe. b. 1988: the origin of patterned ground in n.w. svalhard. pp. 100b1013 in senneset. k. (ed.): proceedings. fifth lnternarional conference o n permafrost. the norwegian committee on permafrost. the norwegian institute of technology. trondheim. washburn. a . l. 1980: g e o c r v o l o g y . a suroey of periglacial processes and enuironmenr. arnold. washingtoninew york. washburn, a . l. 1988: near-surface soil displacemcnt in sorted circles. resolute area. cornwallis island. canadian high arctic. canadian journal of earth science 26. 941-955. akermann, j . 1983: notes on chemical weathering. kapp linne. proceedings. 4th international permafrost conference. 1&16. 406 pp. academia in svalbard: an increasingly important role for research and education as tools for norwegian policy perspective academia in svalbard: an increasingly important role for research and education as tools for norwegian policy ole arve misund university centre in svalbard, longyearbyen, norway; national institute of nutrition and seafood research, bergen, norway; department of biology, university of bergen, bergen, norway abstract svalbard, a high-arctic archipelago over which norway practises sovereignty in accordance with the terms of the svalbard treaty, has become an increasingly important area for arctic research and higher education. there are four more or less permanent settlements with substantial research infrastructure, and a few manned observatories for special purposes. several norwegian and foreign research institutions have established stations and installations in the archipelago. with coal mining activity scaling down because of economic difficulties and lack of political support for subsidies, norwegian policy will prioritize research and higher education as a way of maintaining norwegian settlements in svalbard. i give an overview of the institutions, organizations and facilities for research and higher education in svalbard, and discuss the increasingly important role of research and education in norwegian svalbard policy. keywords arctic; higher education; university centre in svalbard; svalbard treaty; geopolitics; climate research abbreviations npi: norwegian polar institute; sios: svalbard integrated arctic earth observing system; snsk: store norske spitsbergen kulkompani; ssc: svalbard science centre; ssf: svalbard science forum; uit: university of tromsø—the arctic university of norway; unis: university centre in svalbard recent developments in svalbard pose a challenge to the norwegian government, which aims to keep a dominant norwegian presence in the archipelago, which it administers in accordance with the terms of the svalbard treaty of 1925. the treaty recognizes norwegian sovereignty over svalbard, but gives equal rights to the citizens of all the signatory nations (45 as of 2016) to reside there without visas and to engage in commercial activities. the coal mining activity that has for many years been a cornerstone of permanent norwegian settlement in longyearbyen is scaling down, and alternative activities must be found to maintain the norwegian community. developing longyearbyen as a modern family community in the high arctic has long been one of the main priorities of the norwegian government’s svalbard policy. expansion in the public and private sectors is now needed to compensate for the loss of workplaces within the mining industry. the strategic business plan for svalbard (svalbard business association 2014), developed by the business association of svalbard in cooperation with the longyearbyen town council, suggests that the education and research sector could double in the years to come. scientific activities have increased in svalbard during the last decades, and several norwegian and foreign institutions have established research stations and installations in the archipelago. a recent survey shows that visits to svalbard for the purpose of research totalled 61000 person days in 2014, of which norwegian researchers contributed approximately half (aksnes & rørstad 2015). nevertheless, research plays a limited role in maintaining permanent settlements, as most of the activities involve short-term visits by researchers. exceptions include the staff at unis, who live in svalbard year-round. the npi, the ssf and a few other research organizations also have employees stationed in svalbard all year. the norwegian government’s goals and strategies for its svalbard policy, as laid out in two white papers (nmj 2009, 2016) presented to norway’s parliament, the storting, have included consistent and firm enforcement of norwegian sovereignty through proper observance of the svalbard treaty and control to ensure compliance with the treaty. maintenance of peace and stability in the area is prioritized, along with preservation of the area’s distinctive natural wilderness. the government sees the maintenance of norwegian communities in the archipelago as central to enforcing sovereignty through civilian presence. here i briefly describe the scientific infrastructure, organizations and activities in the communities in svalbard and discuss their role in relation to norwegian policy for research, environmental contact ole arve misund ole.arve.misund@unis.no university centre in svalbard, p.o. box 156, no-9171 longyearbyen, norway polar research, 2017 vol. 36, 1308131 https://doi.org/10.1080/17518369.2017.1308131 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1308131&domain=pdf protection and sovereignty. specifically, i discuss the potential for research and educational organizations to take a larger role in the communities where coal mining is being curtailed. svalbard settlements for centuries, svalbard has been an arena for expedition-based polar exploration and resource exploitation by dutch, russian, norwegian, swedish, british, french and others (arlov 2007; avango et al. 2011). exploitation of biological resources started in the early 17th century with whaling, followed by hunting and trapping after 1700. these activities mainly took the form of summer expeditions, but much of the hunting and trapping has been carried out by individuals operating from scattered, rather primitive and isolated stations in the coastal areas of svalbard (reymert & moen 2015). scientific exploration took off during the 19th century and revealed, among other things, valuable mineral deposits. coal mining developed after 1900 and required year-round presence (hacquebord & avango 2009). to produce coal from the relatively rich and easily accessible coal deposits, five more or less permanent villages were established in svalbard: ny-ålesund (norwegian), pyramiden (russian), longyearbyen (norwegian), svea (norwegian) and barentsburg (russian) (arlov 2007; fig. 1). operational difficulties led to closure of the coal mine in ny-ålesund in 1962, and pyramiden was abandoned in 1998. coal mining operations are ongoing in longyearbyen and sveagruva by the norwegian mining company snsk and in barentsburg by the russian company trust arktikugol. however, low prices on the international coal market are forcing the coal mining companies to reduce their activity. in addition, there is political momentum to reduce coal mining on account of the contribution of coal to co2 emissions to the atmosphere (helgesen et al. 2015). the former coal-mining village of ny-ålesund (figs. 1, 2) has been transformed into a base for international high-arctic research. it is run by the norwegian limited company kings bay, which facilitates arctic field stations for polar research institutes from 11 nations (table 1). in winter, the village is maintained by a staff of 25, employed on short-term contracts only, with a maximum residence time of four years. there are no families and no children in the village. cruise vessels are allowed to dock subject to permission. transport to and from longyearbyen is mainly by plane (twice a week), or more infrequently by helicopter or boat. twenty-nine per cent of the research effort (person-years) by norwegian research institutions active in svalbard was carried out in ny-ålesund in 2014 (fig. 3). with a population of 2100 (bjørnsen & johansen 2014), longyearbyen is the northernmost family community in the world. the town has fully developed infrastructure – international airport, harbour figure 1. the svalbard archipelago and its permanent settlements (red dots). 2 o.a. misund facilities, bank, church, hospital, hotels, school, shops, advanced telecommunications and so on. the community is among the most international in norway, with 22% of the population representing 39 nations other than norway (bjørnsen & johansen 2014). there is nearly 100% employment, and 70% of the population is younger than 45 years. average residence time is four to five years. of the person-years of employment produced in svalbard in 2014, coal mining represented 34%, the public sector 25%, education and science 24% and travel and leisure 17% (bjørnsen & johansen 2014). out of the total annual figure 2. nations with various education and research activities in the settlements in svalbard. table 1. research stations and observatories in ny-ålesund (source: http://kingsbay.no/research/research_stations/). station organization country year research topics rabben national institute for polar research japan 1990 arctic environment (atmosphere physics, terrestrial biology, oceanography, glaciology, meteorology) national environment research council british antarctic survey uk 1991 earth and life sciences koldeway alfred wegener institute germany 1991 biology, chemistry, geology, atmospheric physics network for the detection of atmospheric composition change observatory alfred wegener institute germany atmospheric physics, chemistry vlbi – antenna norwegian mapping authority norway 1992 geodesy arctic centre university of groningen netherlands 1995 ecology dirigibile italia national research council of italy italy 1997 environmental research, climate research charles rabot base french polar institute paul émile victor france 1999 atmospheric science, life sciences jean corbel french polar institute paul émile victor france 1999 atmospheric science sverdrup npi norway 1999 environment/ecosystem research zeppelin npi and norwegian institute for air research norway atmospheric chemistry dasan korean polar research institute korea 2002 environmental research, geomorphology, hydrology awipev alfred wegener institute /french polar institute paul émile victor france and germany 2003 joint logistical operation of french and german stations yellow river chinese arctic and antarctic administration china 2004 meteorology, space-earth measurements, glaciology, marine ecosystem, arctic environment kings bay marine laboratory kings bay norway 2005 marine laboratory himadri national centre for antarctic & ocean research india 2008 marine ecosystems, atmospheric science, pollution amundsen–nobile climate change tower national research council of italy italy 2009 atmospheric boundary layers polar research 3 http://kingsbay.no/research/research_stations/ business revenue of about 500 million eur, coal mining contributed 45%, education and science 22%, the public sector 21% and travel and leisure 12% (bjørnsen & johansen 2014). since 2015, this distribution has been changing because of falling prices on the international coal market and their consequences for the local mining company. thirtynine percent of the research effort by norwegian academic institutions active in svalbard was carried out in longyearbyen in 2014 (fig. 3). the ssc is a spectacular edifice located centrally in longyearbyen (mackeith 2006). it houses unis, the svalbard division of the npi, the ssf and the svalbard museum. several other academic organizations such as the uit, the norwegian university of science and technology, sintef, the institute of marine research, the nansen environmental and remote sensing centre, the japanese national institute of polar research and the norwegian scientific academy for polar research have an office – alone or shared – at the ssc. the first building phase of the ssc was completed in 1996 and is owned by unis, whereas phase ii (12000 m2, opened in 2006) is owned by statsbygg, norway’s government property management firm, which rents out facilities to the other organizations. the ssc was evaluated in 2014, and both the building and the societal value of the project were rated high (anonymous 2014). in sveagruva, snsk still operates a coal mine, but the snsk board has decided to suspend mining operations there, a decision recently supported by the company’s owner, the norwegian government. still, there will be some activity in sveagruva to maintain the facilities. use of sveagruva’s infrastructure is rapidly shifting towards educational, research, and tourism activities rather than coal mining. the russian settlement of barentsburg has about 400 permanent residents. trust arktikugol operates a coal mine; there is infrastructure for russian research institutions, and a hotel that is open for tourists. a russian governor oversees activities in the town, but norwegian law prevails and the governor of svalbard is ultimately in charge, as in all of svalbard. barentsburg can be reached by boat, helicopter or (in winter) snowmobile. higher education and research unis has become the dominating research and higher education organization in svalbard. unis’s research activity corresponded to a total of more than 60 person-years in 2014, more than any other academic organization active in svalbard (fig. 3). this is also reflected in the research in svalbard database (see below), in which unis is the organization with the largest project portfolio (fig. 4). about 115 scientific, technical, and administrative staff, and phd students and postdoctoral fellows with permanent addresses in longyearbyen are affiliated with unis. there are an additional 38 adjunct professors in 20% positions and about 160 guest lecturers each year. about 700 students took courses at unis in 2015. altogether, unis staff, fellows and students, and their families, comprise about 20% of the population of longyearbyen. about half the staff and figure 3. the research activity (in person-years) of the organizations active in ny-ålesund, longyearbyen and other sites in svalbard in 2014. 4 o.a. misund nearly 65% of the students come from outside norway. the total budget of unis in 2016 was about 200 million nok, and about half of the budget for direct costs is spent locally. unis is set up for field-based research and education, with a well-functioning logistics unit that can equip staff and students for outdoor activities on land, on ice, or at sea at any time of the year. unis operates the kjell henriksen observatory at breinosa for observations and measurements in the upper and middle atmosphere. the unis co2 lab facility in adventdalen has been used to explore the underground strata and assess the possibility of storing liquid co2 in sealed and permeable sandstone formations (sand et al. 2014). unis is open to students matriculated at norwegian universities who have completed one year of university education in natural science subjects, and who want an arctic profile in biology, geology, geophysics or technology. a cooperation agreement between unis and the norwegian universities ensures that unis courses complement those offered on the mainland. the opportunity to take courses at unis is promoted to students at the norwegian universities, and courses completed at unis give full academic credit. through this arrangement, unis is regarded as the common arctic institute of the norwegian universities. unis is also open to students coming directly from abroad, provided they fulfil the admission criteria; such students are matriculated at uit, in tromsø. the npi has a branch with about 10 permanent staff members at the ssc in longyearbyen. npi has a mandate as a research-based management organization, and acts as an advisor in polar environmental issues to the ministry of climate and environment and to the governor of svalbard. npi runs terrestrial, marine and atmospheric environmental monitoring programmes. in the light season (march–october) scientists and technical staff from the npi’s headquarters in tromsø are active in svalbard (fig. 2). in 2014, npi’s total research activity in svalbard constituted nearly 60 person-years (fig. 3), with research effort rather evenly distributed between ny-ålesund (13 of 59 person-years), longyearbyen (23 of 59 person-years) and other areas in and around svalbard (23 of 59 person-years). the largest universities on the norwegian mainland – the university of oslo, the uit, the university of bergen and the norwegian university of science and technology – have substantial research activity in svalbard (figs. 3, 4). the total research activity of these universities (about 115 person-years) is approximately equivalent to that of unis and the npi together (122 person-years). many other norwegian research organizations also have research activities in svalbard, totalling about 45 person-years (fig. 3). the research activities of the universities and many other research institutes are mainly undertaken as time-limited campaigns rather than requiring permanent staff residing in svalbard. a branch of the research council of norway, ssf is employs three permanent staff members in longyearbyen and has offices in ssc. the ssf’s mandate is to coordinate research in svalbard, to stimulate research cooperation and to administer the database research in svalbard. to obtain permission to go out in the field in svalbard for research purposes, projects must first be registered in ris. research and research cooperation are stimulated through annual arctic field grants and strategic grants through which ssf allocates about 5 million nok for research activities in svalbard. sff calls upon all major research operators in svalbard for coordination meetings twice a year. sios is a project financed by the research council of norway with the aim of establishing an independent organization in the ssc that would coordinate access to stations, observation units and databases for research purposes in svalbard. sios will develop a figure 4. development of number of research projects registered in the research in svalbard (ris) database. polar research 5 knowledge centre to compile the information gathered from the substantial but rather fragmented research activity in svalbard. research organizations from about 10 countries are members of sios. in 2016 sios employed four staff members with permanent addresses in longyearbyen. arctic field stations eleven institutions have established arctic field stations in ny-ålesund (table 1). the research activities in ny-ålesund are coordinated by the ny-ålesund science managers committee. in the summer season, there are scientists at all the stations and the village is full of activity. the npi’s sverdrup station, the zeppelin observatory, the norwegian mapping authority’s station and the joint french–german arctic research base have small permanent staffs to enable measurements and observations also in winter. a record 14 501 research days were logged in nyålesund in 2014 (ssf 2017). russian research in barentsburg dates back to the 1960s. the russian academy of sciences and other russian research institutes have laboratories and units in barentsburg. a rather small group oversees the facilities in winter, and activity appears to increase in summer. for several decades research has been conducted at the stanislaw siedlecki polish polar station in hornsund, mainly in geophysical disciplines. a team of about 10 staff members operate the station through the winter, and in summer the activity can more than double. at hopen and bjørnøya there are manned stations operated by the meteorological institute of norway with four to six staff members working on six-month contracts. their mandate is regular meteorological observations. government policy for research and higher education in svalbard a 2009 white paper presented to the storting highlighted research and higher education as key elements in norwegian activities in svalbard (nmj 2009). the government outlined its desire for the further development of svalbard as a platform for international research, higher education and environmental monitoring, with norwegian polar research taking a leading role. in 2016, the norwegian government presented its updated policy for svalbard (nmj 2016). this gave research and higher education an even more pronounced role in the government’s svalbard policy. to promote the better utilization of the research possibilities in svalbard, the white paper outlined actions to optimize resource use, strengthen coordination and cooperation, prioritize scientific activities, improve research quality, strengthen research leadership, strengthen the scientific bases for higher education and provide open access to data, while minimizing negative environmental impact. one of the most important actions proposed in the white paper (nmj 2016) is that unis, in cooperation with the norwegian universities, develops further to make use of the unique opportunities offered by its location and strives to reach a 50:50 balance between norwegian and foreign students. the government proposes to prolong its prioritization of polar research, especially in svalbard, to enhance the volume and quality of norwegian research in svalbard and to stimulate use of the ny-ålesund facilities by norwegian scientists. increased international cooperation is also suggested. sios is intended to become a subsidiary company under unis, and the ssf will be developed further. the npi will be given overall responsibility for the operative implementation and follow-up of the new strategy for the research village of ny-ålesund, and the ownership of kings bay will be transferred to the ministry of climate and environment. this is the most attention that research and higher education have been given in government white papers about svalbard, and the priorities suggested by the government strongly underline the importance of these activities in norwegian svalbard policy in the years to come. as expected, the document signals further development of unis and indicates that an even closer cooperation with the mainland universities is needed to reach the objective of attracting more norwegian students to svalbard. the ongoing restructuring of higher education in norway, where university colleges are merging with neighbouring universities, will give a larger student base to recruit from. the clear prioritization of polar research, especially in svalbard, further stimulation of the ny-ålesund facilities and the desire for more international cooperation signal the importance of research in norway’s svalbard policy. an evaluation of svalbard research, and development of an overall strategy, will be important tools, and in these matters the research council of norway can build on the overall policy for norwegian polar research developed a few years ago (research council of norway 2014). there has been some controversy about the proposal that the npi should be in charge of prioritizing research in nyålesund, but as a management body under the ministry of climate and environment, the npi is an organization with competence and experience in such matters. moving the responsibility for the norwegian state’s ownership of kings bay to the ministry of climate and environment will facilitate the coordination of norwegian interests in ny6 o.a. misund ålesund since the npi and kings bay will be under the same ministry. future prospects for academia in svalbard under the provisions of the svalbard treaty, many nations have taken the opportunity to establish arctic research stations and facilities in svalbard, either in their own settlements, as in barentsburg or hornsund, or in ny-ålesund, which the kings bay company has managed. most probably, these foreign research stations will be kept running according to the agreements made with norwegian authorities when the stations were established. with the current interest in arctic research, it is to be expected that activities at these stations will remain at the present level for the foreseeable future and will contribute to the continuation of the settlement of ny-ålesund. barentsburg and hornsund are also expected to be maintained as settlements. the strategic business plan for svalbard (svalbard business association 2014) specifically states that unis has the potential to double its activity. the unis board and administration have outlined to the ministry of education and research how such a development could be based on strengthening the existing thematic areas, adding new thematic areas such as arctic safety, climate change and energy transfer, tourism and selected topics in the humanities and social sciences. a building phase iii for ssc is also argued for. gjerdrem and fagernes (2016) were given a mandate to suggest ways to improve the organization of the units under the ministry of education and research. they recommended that unis become an independent management organization (gjerdrem & fagernes 2016). gjerdrem and fagernes (2016) argued that a strategically important organization such as unis should not continue as a limited shareholder company but rather as a unit directly under the ministry of education and research. with an increasingly important role for unis in anchoring norwegian settlement in svalbard, such a development in the status of the organization should be welcomed. this will eventually raise unis to the same management level as the mainland norwegian universities. a prerequisite for working at unis is that the employee lives in longyearbyen. unis provides housing at standard rates. the employee pays taxes – 15.8% of net income – to the norwegian authorities in longyearbyen at a rate that compares favourably to tax rates elsewhere in norway. if the employee stays in longyearbyen for fewer than 187 days per year, the local tax office can decide that the employee shall be taxed according to the rules for mainland norway or his/her home country. thus the employment criteria at unis and svalbard’s local tax regulations are incentives for unis employees to reside in longyearbyen. other incentives are day care, a good school, first-class telecommunications, excellent opportunities for indoor and outdoor sports, a rich cultural scene and the spectacular arctic nature. as a part of the ongoing process of merging institutions of higher learning in mainland norway, the uit proposed (anonymous 2015) incorporating unis and developing a campus in longyearbyen. but unis is a national concern, and would probably not benefit from becoming part of a regionally based university that has its main activities on the norwegian mainland (misund 2015). rather, unis should be further developed along the lines of the basic model that relies on close cooperation on an equal basis with all the norwegian universities. strengthening other research organizations such as the npi, sios and ssf locally in longyearbyen may also contribute to a stable community if new staff members are required to reside permanently in the town. strengthening research in svalbard in general would not necessarily contribute to a stable familybased community if more researchers come to svalbard for a limited period, for instance, to do fieldwork in summertime. ny-ålesund functions well as an arctic outpost station community (i.e., without families), and enables researchers from many countries to visit briefly, mostly in summer. a challenge for norwegian authorities is to stimulate business activities in longyearbyen so that the town does not end up as a larger version of ny-ålesund. even if research and education activities in longyearbyen are doubled, as suggested by the strategic business plan for svalbard (svalbard business association 2014), through strengthening organizations such as unis, npi, ssf and sios, i am afraid this will not compensate for the loss of employment in coal mining. snsk scaled down from more than 400 employees in 2014 to fewer than 100 in 2016. the number of jobs lost in the coal mining industry in the years 2014–16 is therefore of the same order of magnitude as the total norwegian research effort in svalbard of about 303 person-years in 2014. business activities such as tourism, logistics, various services and possibly industrial activities related to fisheries (misund 2014; misund et al. 2016) have to be developed further if the population numbers in longyearbyen are to be maintained. carrying on with activities in sveagruva, which is an industrial site only, will be an even more challenging task when coal mining closes down. unis uses the sveagruva facilities, approximately 1200 person-days per year, for field excursions and research purposes. the site is open to other organizations as well, but so far such use is rather limited. snsk, together with sintef and unis, polar research 7 has launched an initiative called the svea arctic research institute, but the response and support so far have been meagre. for activities related to arctic engineering, sveagruva is an interesting site: snsk operates a harbour, an air field and accommodation facilities, and gives access to its coal mines. sea ice forms regularly during the winter on van miijenfjorden, which is sheltered from the open sea by the island of akseløya, making svea well-sited for studies involving sea ice. in the years to come, science and education will likely constitute the foundation of norwegian settlement in svalbard. the revised policy presented in the recent white paper on svalbard (nmj 2016) makes it apparent that the scientific profile of the main norwegian settlements in the archipelago will evolve through continued development of ny-ålesund as a clean site for environmental research, of longyearbyen for higher education and science within a family town, and of sveagruva as an arena for applied and industrial research in the arctic. acknowledgements npi director jan gunnar winter gave valuable comments on the manuscript and the role of academia in the development of svalbard. janet holmén gave valuable advice on how to improve the english text. dr dag w. aksnes at the nordic institute for studies in innovation, research and education provided fig. 3 and dr karoline bælum at the svalbard science forum provided fig. 4. disclosure statement no potential conflict of interest was reported by the author. references aksnes d.w. & rørstad k. 2015. norsk polarforskning— forskning på svalbard. ressursinnsats og vitenskapelig publisering—indikatorer 2014. (norwegian polar research—research in svalbard. resources invested and scientific publications—indicators 2014.) nifu report 37/2016. oslo: nordic institute for studies in innovation, research and education. anonymous. 2014. svalbard forskningspark. etterevaluering, desember 2014. (svalbard science park. reevaluation, december 2014.) trondheim: norwegian university of science and technology. anonymous. 2015. vil legge unis under tromsø. (unis to be organized under tromsø.) svalbardposten 49, 12–13. arlov t. 2007. svalbards historie. (the history of svalbard.) bergen: fagbokforlaget. avango d., hacquebord l., aalders y., de haas h., gustafsson u. & kruse f. 2011. between markets and geo-politics: natural resource exploitation on spitsbergen from 1600 to the present day. polar record 47, 29–39. bjørnsen h. & johansen s. 2014. samfunnsog næringsanalyse for svalbard 2014. (community and business analysis for svalbard 2014.) nibr report 2014:26. oslo: norwegian institute for urban and regional research. gjerdrem s. & fagernes s.o. 2016. kunnskapssektoren sett utenfra. gjennomgang av organisering av de sentraladministrative oppgaver i kunnskapssektoren. rapport til kunnskapsdepartementet 6. januar 2016. (the knowledge sector seen from the outside. review of the organization of the central administrative tasks in the knowledge sector. report to the ministry of education and research 6 january 2016.) oslo: ministry of education and research. hacquebord l. & avango d. 2009. settlements in an arctic resource frontier region. arctic anthropology 46, 25–39. helgesen l.m., holmén k. & misund o.a. (eds.) 2015. the ice is melting. ethics in the arctic. bergen: fagbokforlaget. mackeith p. 2006. svalbard research centre, norway. architectual record 03.2006, 112–119. misund o.a. 2014. norwegian fisheries: technologically advanced, biologically sustainable and economically profitable. marine technology society journal 48, 17–23. misund o.a. 2015. unis er et nasjonalt anliggende. (unis is of national concern.) svalbardposten 50, 51. misund o.a., heggland k., skogseth r., falck e., gjøsæter h., sundet j., watne j. & lønne o.j. 2016. norwegian fisheries in the svalbard zone since 1980. regulations, profitability and warming waters affect landings. polar science 10, 312–322. nmj (norwegian ministry of justice and public security). 2009. svalbard. stortingsmelding 22. (svalbard. white paper to parliament 22.) oslo: norwegian ministry of justice and public security. nmj (norwegian ministry of justice and public security). 2016. svalbard. stortingsmelding 32. (svalbard. white paper to parliament 32.) oslo: norwegian ministry of justice and public security. research council of norway. 2014. norsk polarforskning. forskningsrådets policy for 2014–2023. (norwegian polar research. the policy of the norwegian research council for 2014–2023.) oslo: research council of norway. reymert p.k. & moen o. 2015. fangsthytter på svalbard 1794–2015. (hunting cabins in svalbard 1794–2015.) longyearbyen: svalbard museum. sand g., braathen a. & olaussen s. 2014. longyearbyen co2 lab—tales of research and education. norwegian journal of geology 94, 77–82. ssf (svalbard science forum) 2017. ny-ålesund. accessed online at http://www.forskningsradet.no/prognett-ssf/ nyalesund/1254001110293 on 07 february 2017. svalbard business association. 2014. strategisk næringsplan for svalbard. (strategic business plan for svalbard.) longyearbyen: longyearbyen town council and svalbard business association. 8 o.a. misund http://www.forskningsradet.no/prognett-ssf/nyalesund/1254001110293 http://www.forskningsradet.no/prognett-ssf/nyalesund/1254001110293 abstract svalbard settlements higher education and research arctic field stations government policy for research and higher education in svalbard future prospects for academia in svalbard acknowledgements disclosure statement references a storm-related origin for the jurassic brentskardhaugen bed of spitsbergen, norway adventdalen harmon d . maher, jr. janusfjellet f m maher, h. d . , jr. 1989: a storm-related origin for the jurassic brentskardhaugen bed of spitsbergen, norway. polar research 7, 61-17. the laterally persistent but thin, jurassic age (bathonian-callovian) brentskardhaugen bed is poorly sorted (often with mud to cobble size), and is crudely normally and/or reversely graded without internal discontinuities. these traits may indicate a short-lived depositional event, and are inconsistent with an origin as a basal, transgressive gravel lag formed in a terrestrial or shoreline setting. mega-storm events on a shallow marine shelf with an underlying condensed section may account for the poor sorting, grading, stratigraphic position and remanie character of the bed. harmon d . maher, jr., dept. of geography and geology, university of nebraska, omaha, 68182, u.s.a.; october 1988 (revised february 1989). janusfjellet f m group brentskardhaugen bed a distinctive and thin conglomerate to pebbly mudstone horizon on spitsbergen occurs between underlying deltaic and shallow marine kapp toscana group strata and overlying, deeper water (below wave base) black shales of the janusfjellet formation. this conglomerate was initially described in detail by frebold (1929, 1930) and informally referred to as the ‘lias con glomerate’ (e.g. parker 1967). the formal strati graphic term of ‘brentskardhaugen bed’ was introduced by parker (1967). a recent and tho rough description and analysis of the bed can be found in backstrom & nagy (1985), and this discussion owes much to their work. the strati graphic assignment of the bed is uncertain. buchan et al. (1965), birkenmajer (1975), and backstrom & nagy (1985) argue that it belongs to the janusfjellet formation (i.e. with the overlying black shales), while parker (1967) and m ~ r k et al. (1982) include it with the underlying triassic to jurassic kapp toscana group (fig. 1). although the exact deposition mechanism is not specified, most authors interpret the brent skardhaugen bed (bb) as a remanie, a gravel lag associated with a quick transgression (flood et al. 1971; birkenmajer 1975; backstrom & nagy 1985) after a widespread depositional hiatus. toarcian to bathonian fossils that are within phos phatic clasts of the bb (backstrom & nagy 1985) represent the sediments reworked during the hiatus. in that black, ostensibly deep-water mar ine shales and siltstones overlie the bb, which is bathonian to early callovian in age, the trans gression is thought t o be a result of a rapid eustatic marh0gda bed 9 1 brentskardhaugenbed < 3 rise at this time (backstrom & nagy 1985; k. maher 1987). backstrom & nagy summarize the depositional history for the bb as follows: ‘during this (aal enian-bathonian) regression the shelf became exposed to coastal erosion with energy high enough to break up parts of the wilhelm~ya formation and concentrate its coarse and resist ant constituents, among these the phosphorite pebbles. a new transgression started probably near the end of the bathonian contemporary with a global elevation of the sea level at the transition between bathonian and callovian. this event led to renewed reworking and final deposition of the remanie sediments forming the brentskard haugen bed’ ( p . 27). m ~ r k et al. (1982) provide a similar account: ‘subsequent [to toarcian] regression and emergence was followed by renewed transgression where the abraded phos phatic material was deposited as a transgressive conglomerate underlying the dark shales of the adventdalen group’ (p. 389). kapp toscana group wilhelmqya fm wllhelm0ya f m 2 ~_.___ 1; de geerdalen f m -----i ~ de geerdalen fm austjqkelen f m i 68 harmon d . maher, jr. the simplest, and perhaps implicit, inter pretation is that the bb is a shoreline con glomerate formed during the transgression. if s o , the conglomerate would be the cumulative result of many tidal cycles and shoreline processes over the duration (albeit possibly short) of the trans gression. the following is a summary of dif ficulties with such an interpretation and a more specific suggestion for the depositional mech anism -that of a mega-storm deposit on a shallow shelf. implications of this mega-storm inter pretation are also discussed. published literature, and observations from southern nordenskiold land, midterhuken, wedel jarlsberg land, and hornsund (treskelodden, fig. 2 ) made during norsk polarinstitutt's 1988 summer field expedition are the basis of the following discus sion. sorting and grading of the bb the bb is poorly sorted. backstrom & nagy (1985) demonstrate that, while the quartz and chert pebble show a much higher degree of sorting (probably inherited from a well sorted con glomeratic source bed), bb phosphatic clasts in the isfjorden area can range in long-axis length from a cm or so up to extremes of 25 cm. field observations also confirm this character for the bb exposed in the western outcrop belt from bellsund to hornsund. the large clasts vary from loosely packed grain support to a carbonate mud (siderite and/or ankerite) and/or sand matrix sup port. the total grain population is very likely polymodal, reflecting a variety of sources. at many localities the bb is also graded (fig. 4). backstrom & nagy's (1985) fig. 6 shows a fining-upwards (normal) grading, and they state, 'in the diabasodden and brentskardet areas the brentskardhaugen bed passes gradually upwards into a 30-150 cm thick microsparitic limestone . . i scattered pebbles of quartz, chert and phosphorite occurring in the lower part of the bed accord with the gradational contact between this unit and the underlying brentskardhaugen con glomerate' ( p . 9). the bb from southern nor denskiold land (flathaugen, fig. 2) is also normally graded (fig. 4). at tilasberget and skiferkammen the bb is reversely graded and at treskelodden the bb shows reverse grading in the lower half and normal grading in the upper. worsley (1986) also shows a photo of the bb near i f \ fig. 2. map trace of brentskardhaugen bed on spitsbergen, modilied from winsnes (1988). western outcrop belt is involved in tertiary age folding and thrusting, while eastern outcrop (isfjorden to agardhbukta) lies within subhorizontal e limb of the central basin syncline. localities referred to in text and map as follows: b = brentskardhaugen area, f = festningen, fi = flathaugen ( s nordenskiold land), h = heimfjella (n wedel jarlsberg land), k = kapp toscana, m = midterhuken, s = skiferkammen, ti = tilasberget, tr = treskelodden. its type locality that shows a reverse grading from sand-sized or finer to large phosphatic clasts. internal stratification and discontinuities such as hardgrounds, bioturbation surfaces and/or paleosoil development were not observed within the conglomerate. the entire bed, usually less than half a meter thick, has the distinct appear ance of representing one, short-lived depositional event. however, very similar conglomerates are found in the underlying wilhelmaya formation; hence, similar depositional events can be inferred. as a single depositional event, the bb is hard to reconcile with a condensed transgressive lag origin, which could be expected to show many internal and lateral discontinuities. the mech a storm-related origin f o r the jurassic brentskardhaugen bed 69 anism producing a poorly sorted layer of wide spread extent is not part of the normal ‘everyday’ litany of near-shoreline mechanisms (deposits of which should be well sorted and laterally discon tinuous, reflecting the high-energy interface environment). phosphate clast shape many of the phosphatic clasts of the bb are smooth and well rounded (e.g. at skiferkammen and tilasberget), traits consistent with substantial reworking during a history of being concentrated as a lag and reworked by near-shore processes. however, several arguments suggest some clasts have retained an original concretionary/nodule shape and texture with minimal reworking. back strom & nagy (1985) note that there is a strong correlation between clast shape and the type of fossil enclosed within. in particular, they indicate: ‘pebble containing piecej of wood or belemnites are oval, or even cigar shaped’ ( p . 19). many wood-cored phosphatic clasts found in the bellsund area show similar ‘cigar’ shapes. such high aspect ratio shapes are not likely the result of rounding and abrasion processes, and might be especially prone to breakage. other clasts approach a perfect sphere. internal laminations, when present, are parallel to the clast’s outer surface. broken pisolitic carbonate-phosphatic clasts later overgrown by subsequent laminae were observed in samples from midterhuken, but angular overgrown edges indicate excavation, reburial and pisolitic growth without significant abrasion. in contrast, other phosphatic clasts within the bb have very irregular shapes with large reen trants (fig. 4). some indentations are clearly related to pressure solution effects at clast contacts, but much of the irregularity reflects original clast shape. the combination of perfect spherical and very irregular forms is consistent with an origin as relatively intact concretionary growths (near sediment surface growth, back strom & nagy 1985), and significant abrasion is not necessary to explain the rounded forms. fossil content and timing the phosphorite clasts contain ammonites, bel emnites, bivalves, and wood and bone fragments. backstrom & nagy (1985, fig. 15) and bir kenmajer & pugaczewska (1975) document a toarcian to aalenian age for the ammonites and a toarcian to bajocian (possibly bathonian) age for the bivalves. overlapping fossil ranges suggest that in the source area for the bb phosphatic clasts marine conditions prevailed throughout this time. given a bathonian to basal callovian age for the bb itself (birkenmajer 1972; backstrom & nagy 1985), the time span left for emergence of the source area, reworking of the phosphate bearing strata and final deposition of the bb is limited to within the bathonian (e.g. backstrom & nagy 1985, fig. 23). any widespread regression and associated hiatus is beneath the stage reso lution provided by the fossil data. an alternate possibility, favored here, is that hiatuses are local and that marine environments occurred within the svalbard area from toarcian (or even earlier) to barremian (the age of the terrestrial festningen member sandstones that overlie the marine janusfjellet formation). south of bellsund the strata underlying the bb have few fossils, and are commonly mediumto coarse-grained wilhelmeya formation sand stones. birkenmajer (1972, 1975) infers a het tangian or older age for these strata. backstrom & nagy (1985) indicate a toarcian age for the underlying strata of the isfjorden area. while not stated, a likely basis for this age is the range of ages of reworked marine fossils in the phosphorite clasts of the bb. however, if the bb was deposited in a marine setting by an offshore trans port mechanism, then the underlying strata could locally be much younger than inferred on the basis of the reworked bb fossil content. furthermore, merk et al.’s (1982) description of this section as a condensed one with many internal hiatuses suggests that the sediments the bb was deposited on were variable in age and character. such an irregular age distribution from shallow shelf sediments is common (walker 1984). this would explain why ‘bathonian bivalves are found in the uppermost part of the wilhelmoya formation of hellwaldfjellet’ (p. 27, backstrom & nagy 1985), toarcian palyno morphs in a shale interval 4.5m below the bb (backstrom & nagy 1985, p. 15), and norian to rhaetian strata underlie the bb at festningen (bjarke & dypvik 1977). the presence of phos phatic sediments within the wilhelmeya for mation indicates deposition overlapped with phosphate nodule genesis and k . maher (1987) 70 harmon d. maher, j r . describes a phosphate cement for a portion of the bb. finally, at wilhelm~ya, shales overlying several phosphatic conglomeratic horizons may have a bajocian/bathonian age (smith 1975). the picture that emerges is of temporally con tinuous, spatially discontinuous, marine depo sition, with phosphate nodule growth occurring before deposition of the bb over surface sedi ments with a range of ages. the bb itself may be diachronous. local and variable stratigraphic gaps at the base of the bb, where present, could be due to shoaling sequences, tidal channel scour, longshore current scour, storm events or other shallow shelf processes. stratigraphic facies relationships backstrom & nagy (1985) propose the name marhogda bed for a 30 to 150cm thick, micro sparitic, partially dolomitized and sideritized limestone bed, overlying and gradational with the bb. the bed is oolitic and contains quartz, chert and glauconite grains. in southern nordenskiold land the matrix of the bb is a sandy, micritic siderite. and underlying micritic siderite beds show cone-in-cone structures and stromatolitic laminations (fig. 3 ) . on midterhuken oolitic and stromatolitic carbonate horizons occur several meters above and below the bb (fig. 3). oolitic, glauconitic carbonates above the bb ( k . maher 1987) may represent the midterhuken equivalent of the marhogda bed of backstrom & nagy (1985). on treskelodden (hornsund), both at the peninsula tip (e side) and at the base of hyrnefjellet, a massive 0.5 m thick micritic sid erite horizon with an upper section with lami nations and cone-in-cone structures is found 18 m below a conglomeratic horizon which may be the bb (dallmann pers. comm.). the particular depositional environment that produced these fe rich carbonates existed locally, before, during and after deposition of the bb. also, locally massive quartz sandstones very similar to those of the underlying wilhelm~ya formation occur above the bb in nordenskiold land and on midter huken. strongly bioturbated sandstones with discon tinuous shale laminations directly overlie the bb in northern wedel jarlsberg land and fine upward into dark marine shales within several meters (fig. 3). glauconite and chamosite grains occur in the bb and in underlying (bjmke & dypvik 1977) and overlying (k. maher 1987) rocks. as environmental indicators (porrenga 1967), these grains, along with the bioturbated and often gradational upper contact of the bb with overlying, extensively bioturbated siltstones sandstones, suggest the conglomerate was deposited near or below fair-weather wave base. similar bioturbated sands occur immediately above the conglomeratic horizon on the south eastern tip of treskelodden, hornsund, but here they are part of a coarsening-upward sequence (fig. 3) that ends with clean, cross-bedded sand stones with rootlets and thin gravel horizons with large wood fragments (dallmann pers. comm.). the sequence immediately above this coarsening upward section is poorly exposed here, and erling siggerud (pers. comm.) reports that a higher conglomeratic horizon, which i did not find, can be found during low tide further east, in which case this conglomerate bed is not the bb. yet, the conglomerate has a significant fe-rich carbonate component, typical of the bb but absent within many of the phosphatic conglomerate horizons within wilhelm~ya, which have a quartz sand matrix. either a coarsening-upwards sequence exists above the bb, or multiple such beds occur, some of limited lateral persistence, and then stratigraphic assignment must be given to the highest such bed. backstrom & nagy (1985) document in the isfjorden area an erosional, discontinuous contact of the bb with the underlying wilhelmoya for mation sandstones, as does birkenmajer (1975) for sw torell land. locally in wedel jarlsberg land and on treskelodden bedding-parallel solu tion surfaces produce an abrupt lower bb contact, but elsewhere the lower contact is distinctly gra dational, with phosphate and other clasts dis persed in the upper part of the sandstone. the sand was most likely a soft substrate during con glomerate deposition, and a reversely graded con tact between the sandstone and bb (fig. 3) suggests possible depositional continuity between the two. locally, similarities in rock types below and above the bb (k. maher 1987; fig. 3 this paper), coupled with a shallow marine character below (mork .:t al. 1982) and a variable, shallow (oolitic carbonates) to below-wave-base (bioturbated, glauconitic, laminated sands) marine character above, and locally gradational upper and lower contacts, suggest the bb could be contained within (not at the base of) a transgressive , t (b l d g r) re ce ss iv e + p o o rl y e xp o se d f la th a u g e n g la u co n iti c (d g y) p e lo id a l q . ch . c, w , b f o ra m s (m g y 0 , y ) m id te rh u k c e n t ila sb e rg e t g o rg e b . c *f ig . (b l) (q y ) , 7 q , c h p h . s s , 9. c d , c (a + w h ) 5 7 p h . q , ch . b, w i q * p , w (w h + i g y ) t ila sb e rg e t m e g a ri p p le l o ca lit y p d ,a r va ri o u s fo rm s o f c ro s s s tr a ti fi ca ti o n c o n g lo m e ra te 5 jj j(1 b io tu rb a ti o n w e a k to s tr o n g sa n d st o n e r r y m e g a ri p p le s fla t p e b b le h o ri zo n 4 2 f w a ; 0 (i 0 ) i s ki fe rk a m m e n 7 sh a le b e o o id s 3 . ? 2 m ix e d c o m p o n e n ts ' ro o tl e ts + i t re ve rs e + n o rm a l g ra d in g e $ th ic kn e ss b $ sh (m ld g y) p 2 t re sk e lo d d e n w w o o d c ca rb o n a te s s s a n d st o n e c d c o m p o u n d f 3 8 co n e -i n -c o n e ca rb o n a te (a n ke ri te . si d e ri te , ra lc it e ) ~ * l ) st ro m a ta lit e s t rl r* st yo lit e s e a m s fi. tp c: , g ra in s iz e : m u d , si lt . sa n d st o n e ( vf , 1. m . c . vc ). co b b le (i n p o o rl y so rt e d o r m ix e d l ith o lo g ic s e ct io n s m a xi m u m si ze s h o w n (i g y + 0 ) co lo r to n e s fr e sh 4 w e a th e re d in cr e m e n ts i, m . d -l ig h t. m e d iu m . d a rk . in m e te rs g y g re y. g r g re e n , b r b ro w n , b l b la ck , o o ra n g e . y ye llo w , $ a. 4 c o n g lo m e ra te c la st t y p e s (g iv e n i n o rd e r of a b u n d a n ce ): c h c h e rt q q u a rt zi te p p h o sp h a te b b o n e fz g 3 s tr a tig ra p h ic s ec tio ns o f h th o lo g e s im m e d ia te ly a bo ve a nd b el ow th e b re n ts ka rd h a u g e n b e d in th e w es te rn fo ld -a n d -t h ru st b e lt o f s ou th er n s pl ts be rg en m id te rh u ke n s ec tio n m od ifie d fr o m k m a h e r's (1 98 7) w es t b ra va ls b e rg e t s ec tio n t re sk e lo d d e n s ec tlo n m o d ifi e d fr o m d a llm a n n , u n p u b lis h e d s ec tio n, m is si ng p o rt io n c on si st s of a c oa rs en in gup w ar d se qu en ce , an d th e co ng lo m er at ic h o ri zo n d e p ic te d m ay n o t be t h e b b (s ee t e xt ) 12 h a r m o n d . m a h e r , j r . a fig 4 photosketches o f slabs of the brentskardhaugen bed a) from kapp toscana. b+c) from flathaugen, d) from tilasberget. c ) reprcscnts the entire bed. a storm-related origin f o r the jurassic brentskardhaugen bed 73 sequence. the conglomerate could occupy a slightly, locally variable position, separating a lower, ,.:ondensed (and hence of variable age) marine section from a more complete section overhead. why it might occupy such a position is discussed below. such an interpretation would relieve the burden of requiring a transgression so sudden as to submerge the bb to beneath wave base without leaving any trace of shelf tide and current processes. instead, shallow-shelf marine conditions gave way to below-wave-base con ditions with the bathonian eustatic rise of uncer tain speed. coarsening-upward cycles in the underlying wilhelm~ya could represent local off shore bar migration (mark et al. 1982; worsley 1986) or delta-lobe progradation. birkenmajer (1984) documents a regressive sequence ending in fluvial-deltaic, plant-bearing, cross bedded sandstones immediately underneath the bb at agardhbukta (e spitsbergen). here, shallow shelf erosion or storm scour may have cut down to such an earlier lobe, removing overlying, possibly marine, strata. interpretation as a mega-storm deposit poorly sorted and graded layers of high lateral persistence are characteristic of turbidites. while most turbidity currents are associated with abyssal and not shelf settings, storm-generated ‘turbidite’ beds within a shelf setting have been increasingly recognized from the record (e.g. brenchley et al. 1979; fiqueirdo et al. 1982; walker 1984 the literature on storm deposits is extensive walker provides a list of references). allen (1985) sum marizes for storm-related deposits: ‘hence we may imagine that a turbidite-like bed of mainly shore-derived sand gradually spreads outwards over the shelf. its base is likely to be erosional, and the lower part may include a lag of shell and other debris scoured up from the nearby shelf’ (p. 265). however, storm ‘turbidites’ differ from abyssal turbidites (discussed later). such a storm interpretation could not only explain the sorting and grading (fiqueirdo et al. 1982) within the bb, but it would also explain: 1) a lack of internal discontinuities and the implication that this was a short-lived depositional event; 2) the local existence of multiple such beds reflecting multiple storm events; 3) an erosional or gra dational base (dependent on the specific storm related mechanism (fiqueirdo et al. 1982) and on a hard versus a soft substrate) and gradational top (backstrom & nagy 1985); 4) a bioturbated top and overlying bioturbated, laminated sand stones and mudstones (representing resumption of normal, below fair-weather wave base pro cesses) at some locales, while at others overlying oolitic carbonates and clean sandstones indicate shallow shelf conditions (i.e. bb deposition occurred in variable water depths); 5) the rela tively intact character of the phosphate nodules (transported by storm event(s), and hence not subject to repeated transport-deposition cycles of a terrestrial or shoreline character). fair-weather bottom shelf currents may have winnowed the soft sediments from around phosphate concretions, prior to any storm transport. both reverse and normal grading are consistent with a storm event, possibly representing the growing and diminishing phases of a storm. a complete record might be reversely graded in the lower portion and nor mally graded in the upper. staining and irregular cementation observed at the base of the bb and extending into the underlying sandstones may represent an ‘under bed‘ (aigner 1982). according to aigner (1982), “‘underbeds” may be regarded as a type of con cretion controlled by the sudden porosity change at the base of the tempestite’ ( p . 191). impor tantly, these underbeds can serve as ‘reference horizons’ the base of storm scour, reworking and redeposition due to their early cementation. several previous storm episodes may be preserved in one final storm deposit as underbed and associ ated hardground clasts (aigner 1982). this possi bility should be investigated for the bb. aigner (1982) also describes steep-walled, lin ear storm scour features at the base of middle triassic storm deposits in sw germany that he calls ‘gutter casts’. k . maher (pers. comm.) reports similar-appearing features from the base of the bb on midterhuken, and fig. 5 of back strom & nagy (1985) may show some possible irregular gutter casts from the base of the bb along the s shore of isfjorden. different conglomeratic facies (clast types and matrix composition) within the bb (e.g. hornsund area, birkenmajer 1975, p. 24) may be due to locally different substrates reworked during storm events, and due to different storm related processes (offshore currents and storm liquefaction), and are worthy of further attention in light of storm-depth determined facies distri butions. 74 harmon d. maher, jr. the occurrence of hummocky cross-strati fication (hcs) in sandstones (one possible hall mark characteristic of a storm deposit; walker 1984: dott & bourgeois 1982) in close strati graphic association with the bb would be expected but was not looked for as i was unaware of its significance and appearance during the field season. eikeland & dypvik (pers. comm.) report hummocky cross-stratification within wilhelm~ya formation sandstones. above the bb it may be obliterated in many places by the intense bio turbation. future workers might look for it, especially in the underlying wilhelm~ya sand stones, where similar size-graded conglomeratic horizons occur in association with mega-ripples (birkenmajer 1972; fig. 3), suggesting a storm origin (fiqueirdo et al. 1982). however, the extent of hcs in wilheim~ya sandstones may reflect more the preservation potential (related to the degree of fair weather reworking) of storm deposits in more shallow parts of the shelf than it does the frequency of storm events. its existence and extent bears only indirectly on whether the bb is storm generated itself. the exact transport mechanism of turbidite like storm deposits is a matter of debate. walker (1984) argues for storm-initiated, gravity-driven turbidity currents, in which case they should flow down-slope. allen (1985) calls upon a wind-setup induced, offshore bottom current. fiqueirdo et al. (1982) reject a gravity-driven turbidite model but describe three mechanisms for storm-related graded layers: 1) storm-induced offshore-long shore currents (as above); 2) bedform migration; 3) storm pumping and liquefaction. they empha size that these are not mutually exclusive mech anisms. but that they likely operate together. gradational contacts of the bb with underlying massive wilhelm~ya sandstones seen in wedel jarlsberg land might represent the operation of the third mechanism. one important aspect of all models for storm deposits is that they represent either offshore and/or longshore transport. transport direction and paleogeography m0rk et al. (1982) and worsley (1986) describe a late triassic and early jurassic median shallow marine shelf with flanking eastern and western shorelines. the western shoreline in late triassic was a deltaic system with extensive offshore bar migration, and changed to an intermittently emergent, starved shallow shelf in early jurassic (wilhelmaya formation times). the eastern shoreline was a delta front barrier located along barents~ya and e d g e ~ y a . both shorelines are inferred to have a general north-northwest trend. birkenmajer (1972) describes mega-ripples within the wilhelm~ya sandstones underlying the bb at tilasberget, van keulenfjorden (fig. 3). at least two horizons with mega-ripples exist. phosphatic graded conglomerates occur in the troughs of the asymmetric mega-ripples (0.8 2.1 m wavelength) which have a trend indicating an n40e transport direction. the long axis of cigar-shaped clasts and bone and wood fragments within this conglomerate was measured and shows one population sub-parallel to the ripple axis and one at a distinct angle to it (fig. 5). the second population suggests a more northerly current direction, and may represent a change in the cur rent direction during diminishing flow. fiqueirdo et al. (1982) in discussing storm deposits associ ated with the holocene transgression on the atlantic coast of the central united states note that ‘the graded deposit will be confined to small areas such as troughs between mega-ripples and sand waves’ ( p . 183). these may represent the ‘swell lags’ of brenner & davies (1973), formed by the in situ reworking of bottom sediments, in this case possibly during the waning stages. using many of the same lines of argument given above (bed grading and poor sorting), at least some of the conglomerates within wilhelmqya also re present storm influenced deposits. measurements of long-axis orientation of cigar shaped clasts within the bb were also made at heimfjella, east of tilasberget. the average direction of s80e suggests a nloe or slow cur rent direction. given the information from tilas berget, nloe is the simplest choice, and this is very similar to the second clast population (oblique to the mega-ripple axes) at tilasberget. observations of current directions in wilhelm~ya formation sandstones of treskelodden show a bimodal or polymodal pattern, but with a domi nant northerly direction, suggesting this may be a long-term dominant, longshore transport direc tion. transport directions to the northeast and north are consistent with a storm origin and the above paleogeography of m0rk et al. (1982). given that the west shore is the most proximal, they would represent some combination of offshore and a storm-related origin for the jurassic brentskardhaugen bed 75 i fig. 5. paleocurrent data for the brentskardhaugen bed and wilhelmoya formation from the tilasberget and heimfjellet areas. a) long-axis clast orientation in conglomerate directly above the mega-ripple surface, tilasberget (fig. 3 for position), n = 14. b) mega-ripple crest orientation, tilasherget, n = 3, 2 surfaces. c) long axis clast orientation in brentskardhaugen bed on heirnfjelkt, n = 9 . d) mean orientation of long axis clast orientations from brentskardet area as reported by back strom & nagy (1985). along-shore transport, both of which characterize storm deposits (walker 1984). backstrom & nagy (1985) document a strong, long-axis, preferred orientation within the bb of the brentskardet area. they infer a n28e or s28w current direction, and note that small cross beds from a sandstone within the bb have a southerly component. if the sandstone represents deposition between two storm events (two con glomeratic horizons), then the southerly direction could be unrelated t o the clast orientation. in any case the bb has a fairly uniform clast orientation at heimfjella and brentskardet, two widely sep arated areas (fig. 2). also, the similarity in orien tation between clasts in the bb and those in underlying conglomeratic layers at tilasberget suggests similar conditions of formation. more paleocurrent analysis from the bb and underlying and overlying sandstones is likely to produce interesting results in the future. singularity of the bb? a mega-storm interpretation for the bb raises the question of how many such events are pre served in the bb and adjacent strata. a one-time super storm for the bb is one possibility, but is philosophically unattractive (postulation of cata strophic events requires extraordinary evidence). in many locales only one conglomeratic horizon separates the wilhelm@ya and janusfjellet for mations, but backstrom & nagy (1985) describe two conglomeratic horizons separated by a sand stone interbed at dr@nbreen, brentskardet area. both are shown with erosional bases on strati graphic columns and, therefore, are likely sep arate events. two closely spaced conglomeratic horizons of very similar character also occur locally on midterhuken (separated by a carbonate bed, k. maher 1987) and in heimfjella (separated by a sandstone bed). the highest horizon in each case might be properly called the bb, but it seems apparent that they represent similar depositional events. these relations give rise to the possibility that the bb is actually not a single, continuous bed, but consists of several laterally-persistent beds within a limited stratigraphic interval that locally overlap each other. conglomeratic horizons that are sometimes poorly sorted and graded (fig. 3) occur through out the wilhelmciya formation (mmk et al. 1982). as forementioned, some of these (e.g. at tilasberget, fig. 3) may also be storm deposits. the lower tilasberget conglomeratic horizons are notably discontinuous, being absent some several hundred meters to the north in a series of excellent exposures of the wilhelm@ya formation and bb (fig. 3). considering these in combination with the bb, at any one locale one t o five or so mega storm events are preserved in the conglomeratic horizons. storm deposits during the time spanned by the wilhelmgya formation, being deposited above fair-weather wave base, would more likely be destroyed by subsequent reworking. some storm sediment may be preserved in local channels filled in by the storm or in other such spotty settings above fair-weather base. the tilasberget mega ripples and trough conglomerates may represent such an occurrence. a much reduced lateral per sistence of wilhelmgya formation storm deposits in comparison to that of the bb is thus explicable. the bb is distinct from the underlying phos phatic conglomerates of the wilhelmciya for 76 harmon d. maher, j r . mation in being more laterally persistent and usually thicker, and in having more of a fine grained carbonate matrix. the bb matrix is simi lar to that of the massive carbonate beds that occur above and below it. a more persistent character is in accord with being deposited below fair-weather base, as is the presence of heavily bioturbated sandstones and mudstone directly overhead. more storm deposits might be expected in the overlying janusfjellet strata, but a bathonian eustatic rise (vail et al. 1977) may have submerged a shallow, flat shelf below even mega-storm wave base at such a rate that only few such events were preserved. during a eustatic rise the sedimentologic potential of a storm will increase in a shallow epicontinental sea by increasing water surface area (and thereby fetch and wave size), and also by submerging shallow sandbars that would act as wave barriers (which would reduce the ‘effective’ fetch). this may explain why the bb is the thickest storm horizon associated with the most extensive reworking. several previous storm events may be recorded as carbonate underbed and/or hard ground clasts (laminated carbonate tabular clasts occur in the nordenskiold land and treskel odden conglomeratic horizons), but this remains to be investigated. with increasing ‘power’ during transgression, the last major storm event before submergence below even mega-storm wave base would likely rework previous events. seilacher (1982) discusses the formation of a shelf equi librium surface near extreme-storm wave base, developed during a sea-level standstill by the win nowing and offshore transport effect of the storms. this may represent an alternate model for the bb, with a formation before, as a storm generated ‘submarine peneplanation’ basal deposit, and not during, a rapid eustatic rise. the term mega-storm is used for the bb in a relative sense if these conglomeratic horizons are storm related, then the bb is the thickest and has the largest clasts, and hence represents the largest storm preserved in the record. also, the storm-related currents necessary t o entrain 15 to 25 cm sized phosphate clasts are notable. while channel currents could be large enough, the bb is a ‘sheet’ deposit and not a channel deposit. conclusions 1) the poorly sorted and locally graded character of the brentskardhaugen bed, along with the lack of internal discontinuities, is inconsistent with a ‘stratigraphic’ origin (fiqueirdo et al. 1982) of a terrestrial or shoreline deposit formed during a quick transgression. instead, locally the bb is likely the result of a short-lived depositional event, specifically a mega-storm turbidite on a shallow shelf. throughout spitsbergen, probably more than one storm event is represented by the bb. 2 ) extensive reworking and abrasion is not necessary to explain the smooth, rounded phos phate clasts within the bb. although they clearly were excavated from older marine strata (bir kenmajer 1972; backstrom & nagy 1985), win nowing by a variety of shallow shelf currents during condensed sedimentation and entrainment and transport of excavated fossiliferous con cretions by storm events may have produced the bb’s remanie character. 3 ) marine fossils, of toarcian to bathonian age, found within the phosphate clasts limit a period of widespread exposure and erosional hiatus prior to bb deposition to within the bathonian ( < 3 ma). an alternate interpretation, of local, variable stratigraphic gaps due to shoaling and shallow shelf submarine erosion within the con densed section, is preferred. 4) the stratigraphic position of the bb is that which would be expected from (a) storm deposit(s) between underlying, mostly shallow marine, shelf sediments and overlying, above overall, deeper water sediments. locally, similar facies exist below and above the bb ( k . maher 1987), consistent with a storm deposit punctuating ‘normal’, fair-weather processes, with deposition in variable water depths. 5) sparse paleocurrent data are equivocal, but are presently consistent with an offshore/long shore transport component typical of a storm deposit. the tilasberget locality (birkenmajer 1972) is especially informative in this regard. 6) locally, more than one size-graded, poorly sorted layer occurs at the bb interval; hence, more than one storm event is represented. similar ‘lag’ gravels within the wilhelmcdya formation strata beneath may represent other storm deposits. 7) as a transgressive lag deposited after a wide spread hiatus, the bb would correctly be included with the overlying janusfjellet formation (bir kenmajer 1975; backstrom & nagy 1985). as a storm deposit on a shallow shelf submerged below a storm-related origin f o r the jurassic brentskardhaugen bed 77 wave base during a bathonian eustatic rise, the stratigraphic assignment would be less certain. however, inclusion within the kapp toscana groups (mark et al. 1982) would be consistent with the existence of similar horizons in the wilhelm0ya formation, and would also more or less separate shallow shelf, above wave-base sedi ments from below wave-base deposits. the base of the bioturbated shale to siltstone sequence of the lower janusfjellet formation would be more precise in making such a separation. acknowledgements. i would like to thank the following people and organizations: winfried dallmann, for providing stimu lating discussion and detailed stratigraphic sections from kapp toscana and treskelodden, and for reviewing an early version of the paper, ntnf of the norwegian government, which provided a fellowship without which this work would not have been possible, norsk polarinstitutt for providing logistical and much other support, university of nebraska at omaha for granting leave and giving support, two anonymous reviewers, who provided valuable criticisms and suggestions, and mary trahman for help in final manuscript preparation. references aigner, t . 1982: calcareous tempestites: storm dominated stratification in upper muschelkalk limestones (middle trias, sw-germany). pp. 18&198 in einsele, g . & seilacher, a . (eds.): cyclic and euent stratification. springer-verlag, berlin. allen, j. r. l. 1985: principles of physical sedimentology. allen and unwin, london. 272 pp. backstrom, s. a . & nagy, j. 1985: depositional history and fauna of a jurassic phosphorite conglomerate (the brent skardhaugen bed) in spitsbergen. norsk polarinstitutt skrifter 183, 1-61. birkenmajer, k. 1972: megaripples and phosphorite pebbles in the rhaeto-liassic beds south of van keulenfjord, spits bergen. norsk polarinstitutt arbok 1970, 117-120. birkenmajer, k. 1975: jurassic and cretaceous sedimentary formations of sw torell land, spitsbergen. studia geologica polonica 44, 7-14. birkenmajer, k. 1984: regressive deposition in the de geer dalen formation (rhaeto-liassic) at agardhbukta, east spits bergen. studia geologica polonica 80, 47-58. birkenmajer, k. & pugaczewska, h . 1975: jurassic and lower cretaceous marine fauna of sw torell land, spitsbergen. studia geologica polonica 44, 75-104. bjierke, t. & dypvik, h . 1977: sedimentological and paly nological studies of upper triassic-lower jurassic sediments in sassenfjorden, spitsbergen. norsk polarinstitutt arbok 1976, 131-149. brenchley, p. j., newall, g. & stanistreet, 1. g. 1979: a storm surge origin for sandstone beds in an epicontinental platform sequence, ordovician, norway. sedimentary geology 22, 185-217. brenner, r. l. & davies, d. k. 1973: storm-generated coyui noid sandstone: genesis of high-energy marine sediments from the upper jurassic of wyoming and montana. geo logical society of america bulletin 84, 1685-1697. buchan, s. h., challinor, a , , harland, w. b. & parker, j. r . 1965: the triassic stratigraphy of svalbard. norsk polar inrtitutt skrifter 135, 1-94. dott, r. h . , jr. &bourgeois, j . 1982: hummocky stratification: significance of its variable bedding saquenccs. geological society of america bulletin 93, 663-680. fiqueirdo, a. g., jr., sanders, j. &swift, d. j. p. 1982: storm graded layers on inner continental shelves: examples from southern brazil and the atlantic coast of the central united states. sedimentary geology 31, 171-190. flood, b., nagy, j . & winsnes, t. s. 1971: geological map of spitsbergen, southern part. norsk polarinrtitutt skrifter i54a. frebold, h . 1929: oberer lias und unteres callovien in spitz bergen. skrifter om sualbard og ishauet 20, 1-24. frebold, h. 1930: verbreitung und ausbildung des meso zoikums in spitsbergen. skrifter om soalbard og ishauet 31, 1-126. maher, k. 1987: thestructure andstratigraphy of lower meso zoic strata, midterhuken peninsula, west spitsbergen, sual bard. m.s. thesis, university of wisconsin, madison, wi, u.s.a. 286 pp. m a k , a . , knarud, r . & worsley. d . 1 9 8 2 depositional and diagenetic environments of the triassic and lower jurassic succession of svalbard. pp. 371-398 in embry, a . f. & blackwell, h. r . (eds.): arctic geology and geophysics. canadian society of petroleum geologists memoir 8 . parker, j. r . 1967: the jurassic and cretaceous sequence in spitsbergen. geological magazine 104,487-505. porrenga, d. h. 1967: glauconite and chamosite as depth indicators in the marine environment. marine geology 5 , 495-501. seilacher, a . 1982: general remarks about event deposits. pp. 161-174 in einsele, g . & seilacher, a. (eds.): cyclic and euent stratification. springer-verlag, berlin. smith, d. g. 1975: the stratigraphy of wilhelms~ya and hellwaldfjellet, svalbard. geological magazine 112,481-491. vail, p. r., mitchum, r. m. & thompson, s. 1977: seismic stratigraphy and global changes in sea level. american associ ation of petroleum geologists memoir 16, 1-97. walker, r. g. 1984: shelf and shallow marine sands. pp. 141 170 in geoscience canada reprint series 1 . facies models (2nd ed.). geological association of canada. winsnes, t . s. 1988: geological map 1:1ooo000. bedrock map of svalbard and jan mayen. norsk polarinstitutt temakart 3 . worsley, d. 1986: the geological history of sualbard euol ution of an arctic archipelago. den norske stats oljeselskap, stavanger, noway. 121 pp. no job name the water column as an attenuating factor of the uvr effects on bacteria from a coastal antarctic marine environmentpor_111 390..398 edgardo a. hernández,1 gustavo a. ferreyra,2 lucas a.m. ruberto1,3 & walter p. mac cormack2 1 cátedra de biotecnología, facultad de farmacia y bioquímica, universidad de buenos aires, a. junín 956 6° piso, código postal c1113aad, buenos aires, argentina 2 instituto antártico argentino, cerrito 1248, código postal c1010aaz, buenos aires, argentina 3 consejo nacional de investigaciones científicas y técnicas, rivadavia 1917, código postal c1033aaj, buenos aires, argentina abstract the effect of uvr on the viability of the culturable bacterial community fraction (cbc), and two of their isolated components (arthrobacter-uvvi and bizionia-uvps), was studied in the top few metres of the water column at potter cove, king george island, antarctica. quartz flasks containing cbc from surface waters were exposed to solar radiation at depths of 0, 1 and 3 m. similar experiments using uvps and uvvi isolates were performed. in some experiments interferential filters were used to discriminate photosynthetic active radiation (par), uv-a and uv-b. cbc from depths of 0, 10 and 30 m were also exposed to surface solar radiation. the deleterious effect of uvr was observed at the surface and at a depth of 1 m, but not at a depth of 3 m. studies with interferential filters showed low bacterial viability values at depths of 0 and 1 m under both uvr treatments. however, under low radiation doses the effect attributed to uv-b was higher than that caused by uv-a. the surface cbc was more resistant to uvr compared with cbc from a depth of 30 m. the results showed that cbc inhabiting waters above the pycnocline (located at a depth of 5–10 m) are more efficiently adapted to uvr than are those from below the pycnocline. the impact of uvr on the marine bacterioplankton studied was only detected in the first metre of the stratified water column of potter cove, which has high levels of suspended particulate matter. these results support the evidence for a significant uvr-attenuating effect in the water column of this coastal antarctic water. keywords antarctica; marine bacteria; psychrotolerants; uv radiation; water column. correspondence walter mac cormack, instituto antártico argentino, cerrito 1248, código postal c1010aaz, buenos aires, argentina. e-mail: wmac@ffyb.uba.ar doi:10.1111/j.1751-8369.2009.00111.x the water column represents a selective filter for the different uvr bands (280–400 nm), with uv-b (280– 315 nm) being more strongly attenuated than uv-a (315–400 nm) and photosynthetic active radiation (par; 400–700 nm) (smith & baker 1979). the antarctic waters of the open ocean are typically oligotrophic, and are characterized by low concentrations of suspended particulate matter, as well as low levels of phytoplankton biomass and productivity (hapter et al. 1983; schloss et al. 1997). under such conditions, the biological effects of uvr can be detected down to ca. 30 m in depth (karentz & lutze 1990). however, in coastal antarctic environments, the uvr transmitted through the water column can greatly fluctuate as a result of significant changes in the optical properties across different seasons. potter cove is a shallow inlet (50–100 m in depth) receiving a high input of suspended particles from freshwater run-off, mainly during the spring–summer period (klöser et al. 1994; varela 1998; schloss et al. 2002). the combination of a strong shallow pycnocline and high levels of suspended particles result in a low penetration of light through the water column, but there is also a high residence time of particles and microorganisms within the first ca. 5 m (schloss & ferreyra 2002). consequently, the surface layer of potter cove represents an interesting natural model to investigate the response of cells suspended in the water column to solar radiation. it is well known that the antarctic region has been exposed, in the last few decades, to increased levels of uv-b as a result of the reduction in the thickness of the stratospheric ozone layer (staehelin et al. 2001). several papers have shown that uv-b causes direct damage to polar research 28 2009 390–398 © 2009 the authors390 mailto:wmac@ffyb.uba.ar marine microorganisms, including bacteria (vincent & neale 2000). bacteria seem to be more sensitive to uv-b than other planktonic microorganisms because of their small size (jeffrey et al. 1996; boelen et al. 2001). on the other hand, uv-a is not significantly filtered by the ozone layer, and some authors have reported that such wavelengths, rather than uv-b, are the main factor causing deleterious effects on marine microorganisms (booth et al. 2001; hernández et al. 2004). as many of the previous studies investigated the effects of exposing bacterioplankton to direct sunlight using interferential filters, or exposing them to artificial radiation from lamps, the in situ effects of uv-a and uv-b on marine microorganisms suspended at different depths in the water column have been poorly analysed. although it is known that the culturable bacterial communities (cbc) only represent a minor fraction of the entire bacterioplankton community (sherr et al. 2001), knowledge of the responses from this fraction, as well as from isolated strains, is a useful tool for inferring the response of the marine bacterial community as a whole. for example, fernandez zenoff et al. (2006) used the cbc to evaluate the effect of uv-b on the bacterial flora from high-altitude wetland waters. therefore, the main goals of this work were: (1) to study the effects of solar radiation on the cbc from surface waters in the first 3 m of the water column, and compare it with those observed for two previously described antarctic marine bacterial isolates; (2) to discriminate the effects of par, uv-a and uv-b on the same biological models; (3) to analyse changes in the viability of cbc obtained from three different depths (0, 10 and 30 m) after exposure to surface uv irradiance. materials and methods study area and bacterial strains field experiments were carried out at potter cove, king george island (isla 25 de mayo), 62°14′s, 58°40′w, south shetland islands, antarctica. laboratory experiments were conducted in the argentinean–german dallmann laboratory at jubany station (argentina), located on the shore of the potter peninsula. the bacterial strains used in this study, arthrobacter uvvi (a pleomorphic, yellow-pigmented gram-positive strain) and bizionia uvps (a gram-negative orangepigmented rod strain), were isolated and characterized previously (hernández et al. 2004). partial 16s rdna sequences of bizionia uvps and arthrobacter uvvi are deposited in genbank under the accession numbers ay220353 and ay220354, respectively. light measurements the incident solar radiation was measured continuously using a multichannel uv spectroradiometer developed at the alfred wegener institute for polar and marine research. this instrument is based on a bentham dm 150 double monochromator (bentham instruments, reading, berkshire, uk), with a multichannel detector system. underwater light measurements were made using an underwater spherical quantum sensor (li 193 sa), and an underwater spectroradiometer (also developed by the alfred wegener institute), similar to the ground-based instrument, mounted in a waterproof housing. the uv-b sensor measures irradiance of 280–323 nm. the underwater instruments were deployed from a small zodiac boat (for a more detailed description, see richter et al. 2008). experimental designs experiments conducted in the water column during the antarctic summers 2003/04 and 2004/05 were made using a set of quartz bottles containing 50 ml of either seawater or mixed bacterial suspension. quartz bottles were submerged into the water column and maintained at three fixed depths: surface, 1 m and 3 m. in experiment 1, a surface water sample previously filtered through a 2-mm pore cellulose filter was placed into the quartz bottles. the aim of this experiment was to analyse the response of the cbc from the surface when exposed to solar radiation at different levels of the water column. in experiments 2–5, quartz flasks contained suspensions of the isolated bacteria. these suspensions were prepared from liquid cultures of each isolate under exponential growth phase, and contained approximately 107 colony-forming units per ml (cfu ml-1). aliquots of these cultures were diluted 1 : 100 in sterile seawater, and were then placed into the quartz bottles for each experiment. in experiments 4 and 5, interferential filters (mylar and plexiglas) were used to cover the flasks, thereby determining four different treatments (by triplicates): (1) dark control (i.e. black filter); (2) par, covered with a 420-nm cut-off filter (plexiglas uf3; arkema, phildelphia, pa, usa); (3) uv-a (par + uv-a), covered with a 320-nm cut-off filter (mylar; dupont, wilmington, de, usa); (4) uv-b (par + uv-a + uv-b) (quartz bottles without filters). in addition, two experiments (6 and 7) were carried out on land. quartz bottles were filled with 50 ml of previously filtered (with a 2-mm pore filter) seawater obtained from depths of 0, 10 and 30 m. flasks were placed in an incubation chamber and exposed to solar radiation on the shore of potter cove. the chamber was immersed in a continuous water circulation uv effect on antarctic bacteriae.a. hernández et al. polar research 28 2009 390–398 © 2009 the authors 391 bath to minimize thermal oscillations in the flasks (the average temperature during the assay was 4.7 � 1°c). in this case, interferential quartz filters (schott, mainz, germany) were used to cover the top of the flasks, and the same four treatments (by triplicates), described above, were used (i.e., dark, par, uv-a and uv-b). in all experiments, samples from the different treatments were taken at 2 and 6 h. serial dilutions of the samples were plated (0.1 ml) on marine agar (difco 2216; bd, franklin lakes, nj, usa) and incubated in the dark for 30 days at 4°c. counts were performed on plates presenting 30–300 colonies, and the results were expressed as cfu ml-1. hereafter, we express the decreases in bacterial counts as a “loss of viability”. although it is known that only a fraction of any bacterial community is able to grow on a nutrient medium, we used the term bacterial viability in reference to the culturability of the studied bacterial community and isolated strains. the uv-b dose received by the bacterial suspension for each experiment is shown in table 1. statistical analysis the bacterial counts data were analysed by repeated measures anovas, tukey’s multiple comparison tests and dunnet contrasts. results effect of uvr on the bacteria of the water column the water column proved to exert an attenuating effect on uvr, thereby reducing the loss of viability of the cbc from potter cove. figure 1 shows changes in the viability of the surface cbc after exposure to solar radiation (at depths of 0, 1 and 3 m), incubated in flasks without interferential filters. at the surface, significant deleterious effects (p < 0.05) were observed after 2 h of exposure (uv-b dose 3.2 kj m-2): i.e., the cbc changed from 1.15 ¥ 104 at the start of the time period to 2.70 ¥ 103 cfu ml-1 after exposure. this effect was 4.5fold higher after 6 h of exposure, when the uv-b dose reached 4.6 kj m-2. the cbc was also significantly affected (p < 0.01) at a depth of 1 m, but to a lesser extent. in this case, the counts were 7.50 ¥ 103 and 2.75 ¥ 103 cfu ml-1 at 2 and 6 h, respectively. on the other hand, no significant negative effects were observed at a depth of 3 m. when the two marine isolates were exposed to the same experimental conditions, we observed that after 2 h of exposure at a depth of 0 m (with a uv-b dose of 8.4 kj m-2) both strains showed a significant decrease in viability, compared with the dark treatment (p < 0.05). the viable count of strain uvvi was reduced by 50%, table 1 doses of uv-b radiation measured at the indicated sampling times during the different experiments performed at potter cove, king george island, antarctica. uv-b dose (kj m-2) exp. 1 2 h 6 h 0 m 3.20 4.60 1 m 0.61 0.80 3 m 0.017 0.028 exp. 2 0 m 8.37 20.11 1 m 2.09 5.02 3 m 0.008 0.002 exp. 3 0 m 1.20 4.33 1 m 0.33 1.20 3 m 0.025 0.093 exp. 4 0 m — 9.50 1 m — 1.90 3 m — 0.04 exp. 5 0 m — 4.80 1 m — 1.21 3 m — 0.076 exp. 6 3.80 7.28 exp. 7 2.35 3.50 fig. 1 effect of solar radiation on the viability of the surface culturable bacterial community (cbc) placed on the water column at depths of 0, 1 and 3 m (experiment 1). viability was evaluated at the beginning of the experiments (t0), at 2 h (t2) and at 6 h (t6). *p < 0.05, **p < 0.01; irradiance treatments compared with dark controls at the same depths. error bars indicate the standard deviation of triplicates. uv effect on antarctic bacteria e.a. hernández et al. polar research 28 2009 390–398 © 2009 the authors392 whereas the viable count of strain uvps was reduced by 90% (fig. 2). at the end of this experiment (6 h) the uv-b dose at the surface was 20.1 kj m-2, and both strains showed viability values of lower than 1%. at a depth of 1 m, the uv-b dose reached 2.1 kj m-2 after 2 h, and the viability was 45% for both strains. however, after 6 h, the viability values were reduced to 25% and 1% for uvvi and uvps, respectively. finally, at a depth of 3 m the exposure to uv-b was very low (8.4 ¥ 10-3 kj m-2). in this case strains did not show significant differences in viability between irradiated and dark conditions. when the same experimental set-up was with a lower solar irradiance, the deleterious effects were strongly attenuated (fig. 3). this observation was reflected by the viability values observed at the end of the assay (after 6 h), when the uv-b dose at the surface was 4.3 kj m-2. under such conditions, uvvi showed a significantly lower viability value (10%, p < 0.05) only at the surface. in fig. 2 effect of solar radiation on the viability of strains uvps (bizionia) and uvvi (arthrobacter) placed on the water column at depths of 0, 1 and 3 m, when the total uv-b dose at the surface was 20.11 kj m-2 (experiment 2). the viability was evaluated at the beginning of the experiments (t0), at 2 h (t2) and at 6 h (t6). *p < 0.05, **p < 0.01; irradiance treatments compared with dark controls at the same depths. error bars indicate the standard deviation of triplicates. fig. 3 effect of solar radiation on the viability of strains uvps (bizionia) and uvvi (arthrobacter) placed on the water column at depths of 0, 1 and 3 m, when the total uv-b dose at the surface was 4.33 kj m-2 (experiment 3). the viability was evaluated at the beginning of the experiments (t0), at 2 h (t2) and at 6 h (t6). *p < 0.05, **p < 0.01; irradiance treatments compared with dark controls at the same depths. error bars indicate the standard deviation of triplicates. uv effect on antarctic bacteriae.a. hernández et al. polar research 28 2009 390–398 © 2009 the authors 393 contrast, the uvps strain showed significant decreases in viability (p < 0.01) not only at the surface but also at a depth of 1 m (to 1 and 10%, respectively). no significant effects were observed on both strains at a depth of 3 m (p > 0.05). differential effects of uv-a and uv-b on the isolated strains the use of interferential filters confirmed that par radiation had no effect on the studied strains at any of the irradiance regimes or depths tested in this work, and that all negative effects observed on the strains were related to uvr (data not shown). consequently, the effects of uv-a on both strains were expressed in terms of the fractional loss of viability (flv%), determined with the following equation: 1 100− [ ]( ) ×cfu cfuuv-a par , where cfuuv-a represents the cfu in the uv-a treatment, and cfupar represents the cfu in the par treatment. in the same way, the flv% resulting from exposure to uv-b was calculated as: 1 100− [ ]( ) ×cfu cfuuv-b uv-a , where cfuuv-b represents the cfu in the uv-b treatment. in one of the assays (fig. 4), the surface uv-b dose was 9.5 kj m-2 after 6 h of exposure. in this case, a high flv% for the strain uvvi resulted from exposure to uv-a at both the surface (70%) and at a depth of 1 m (52%; p < 0.05). the presence of uv-b did not add any significant effect at these depths. this fact is reflected by an flv% close to 0 for the uv-b treatment. at a depth of 3 m, strain uvvi was not affected by exposure to uv-a, whereas exposure to uv-b produced only a weak negative effect (13% flv). under the same conditions, the other strain (uvps) was also deeply affected by uv-a at depths of both 0 and 1 m (fig. 4), showing higher flv% values than those observed for uvvi (99.9 and 94%, respectively). the magnitude of the responses to uv-b was similar, with flv values of 90.4 and 99.0% at depths of 0 and 1 m, respectively. at a depth of 3 m, uv-a had no effect on the viability of uvps, but uv-b caused significant deleterious effects (46.5% flv). under a uv-b dose of approximately half that registered during the experiment described above (4.8 kj m-2 at 6 h; fig. 5), only uv-a affected the viability of the two strains at the surface, with the effect on strain uvvi (22% flv) being less than that found for uvps (31% flv). neither uvvi nor uvps strains evidenced negative effects at depths of 1 and 3 m upon exposure to uv-a. in contrast, the exposure of strain uvvi to uv-b resulted in significant inactivation (p < 0.05) at depths of 0 and 1 m, which was evidenced by the flv% values (65 and 19%, respectively). uvps was also affected at the same depths (97% flv at 0 m and 67% flv at 1 m), showing a higher sensitivity to this uvr band than uvvi. finally, although the flv% values were positive (18 and 21% for uvvi and uvps, respectively) upon exposure to uv-b at a depth of 3 m, these values were not significantly different from those caused by uv-a. effect of uvr on cbc obtained from different depths in the water column when the cbc obtained from depths of 0, 10 and 30 m were exposed to solar radiation reaching the surface of the earth, we observed different responses depending of the depth from which the cbc were obtained, but also depending on the radiation dose. as shown in table 1, during the first 2 h of experiment 6 the bacterial cells received one-half of the total dose of the full experiment, even though 2 h represents only a third of the total expofig. 4 the fractional loss of viability (flv%) observed for strains uvps (bizionia) and uvvi (arthrobacter) placed on the water column at depths of 0, 1 and 3 m, when the total uv-b dose at the surface was 9.5 kj m-2 (experiment 4). see text for details about the calculation of flv. error bars indicate the standard deviation of triplicates. uv effect on antarctic bacteria e.a. hernández et al. polar research 28 2009 390–398 © 2009 the authors394 sure period. this fact could in part explain the high loss of viability observed in this initial period of exposure (table 2). after 2 h (with a uv-b dose of 3.8 kj m-2) the surface cbc was only affected after exposure to uv-b, whereas the cbc from depths of 10 and 30 m were significantly (p < 0.05) affected by exposure to both uv-a and uv-b. however, whereas the cbc from a depth of 10 m was more affected (p < 0.05) by exposure to uv-b than to uv-a, the cbc from a depth of 30 m showed similar losses of viability under both uv treatments. it is important to note that the negative effect of uv-b on the surface cbc was significantly lower (p < 0.05) than on cbc from depths of 10 and 30 m, which showed no differences between them. when the uv-b dose was 50% lower than that registered for experiment 6, as was the case in experiment 7, cbc from depths of 0 and 10 m responded in a similar way, showing no significant differences when compared with the dark controls. under these conditions, cbc from a depth of 30 m showed a significant loss of viability (p < 0.05), with the effect of exposure to uv-b being significantly greater (p < 0.05) compared with uv-a. significant differences between par and dark treatments were not observed during both experiments (data not shown). discussion it is well known that concentrations of suspended particulate matter (spm) and dissolved organic matter (dom) in the water column strongly scatter and absorb uvr, potentially reducing the damaging effects on cells. such uvr decrease is mostly evidenced in coastal waters, and is more marked in the uv-b range than in the uv-a range (tedetti & sempéré 2006). studies performed in tropical coastal waters reported that uv-b values were attenuated by more than 90% in the first metre of the water column (wilhelm et al. 2002). a similar situation was observed in the present studies at potter cove, where uv-b was attenuated by ca. 99% at a depth of 3 m. most of the light absorption in the water column of potter cove can be related to the high spm load originating from terrestrial freshwater inputs during spring and summer (klöser et al. 1994). a recent study by richter et al. (2008) determined that for some days during summer there is severely reduced uvr penetration, with uvr being completely absorbed at a depth of 2 m. on the other hand, gustavson et al. (2000) have reported that the uv-b-induced photodegradation of dom may enhance carbon availability, and hence bactefig. 5 the fractional loss of viability (flv%) observed for strains uvps (bizionia) and uvvi (arthrobacter) placed on the water column at depths of 0, 1 and 3 m, when the total uv-b dose at the surface was 4.8 kj m-2 (experiment 5). see text for details about the calculation of flv. error bars indicate the standard deviation of triplicates. table 2 percentage of viability observed for culturable bacterial communities (cbc) from depths of 0, 10 and 30 m, exposed to surface photosynthetic active radiation (par) + uv-a, and par + uv-a + uv-b solar radiation (experiments 6 and 7, respectively). 0-m cbc 10-m cbc 30-m cbc 2 h 6 h 2 h 6 h 2 h 6 h exp. 6 uv-a 88.45 � 23.55 103.8 � 16.26 66.66 � 4.19* 57.68 � 7.61* 37.57 � 18.85** 37.04 � 18.73** uv-a + uv-b 62.82 � 5.44 71.79 � 10.88 46.66 � 9.42* 35.38 � 6.53** 40.60 � 5.99** 29.24 � 1.65** exp. 7 uv-a 95.28 � 12.54 98.25 � 7.43 86.00 � 6.36 91.15 � 11.71 32.50 � 3.53** 32.99 � 6.46** uv-a + uv-b 77.92 � 19.47 93.57 � 3.51 89.75 � 8.83 87.84 � 17.18 26.25 � 1.76** 20.81 � 5.74** *p < 0.05, **p < 0.01; irradiance treatments compared with dark controls at the same depths. uv effect on antarctic bacteriae.a. hernández et al. polar research 28 2009 390–398 © 2009 the authors 395 rial activity, potentially compensating for the growth losses caused by damage to cellular dna. this fact could lead to a compensation of the negative effects of uv-b, and to the absence of a net change in bacterial activity. however, this is not the case for this study, where the negative effect of uv-b on the antarctic bacteria analysed seems to overcome any possible positive effect resulting from the increase in nutrients available for bacterial growth. this hypothesis can be supported by the low dom concentrations (<50 mm c) reported for potter cove (abele et al. 1999; ferreyra et al. 2008). despite the limitations of the culture methods to study bacterial communities, which were mentioned in the introduction, a number of recent studies have used the culturable fraction to analyse functional characteristics as well as the responses to environmental changes (frette et al. 2004). for example, fernandez zenoff et al. (2006) reported a significant decrease in cell numbers after exposure to uvr, using the cbc to infer the effect of solar radiation. in addition, when the goal of research is to analyse changes in the viability of cells, or in the components of the community, occurring within short time scales (i.e., a few hours), as was the case in our study, the evaluation of the culturable fraction of the bacterial community and their loss of viability could be a more realistic approach than the qualitative and quantitative evaluation of the components by molecular methods. in these cases, independently of their physiological state, or if the bacterial cells are dead or alive, dna of all the original components will remain in the suspension during the whole period studied, leading to the detection of bacterial groups that are not really active at the time of sampling. in our study, the cbc from the surface showed no adaptation to the solar radiation reaching the surface waters. this fact is suggested by the loss of viability observed after only 2 h of solar exposure. this deleterious effect on surface cbc was also observed to a minor extent at a depth of 1 m, but was not significant at a depth of 3 m, where the water column seemed to completely attenuate the effect of solar radiation. the results obtained with the isolated strains suggest that each component of the cbc has a different response to radiation, and that some components are more sensitive and others more resistant than the cbc analysed as a whole. not all of the cbc components exhibit total resistance to radiation, as would be expected from a cbc that was fully adapted to such conditions. this result differs to some extent from those obtained by helbling et al. (1995), who found that two bacterial isolates were more sensitive to solar radiation than the cbc from the same site. they also reported that a gram-positive isolate (bacillus sp.) was more sensitive than a gram-negative acinetobacter sp. in previous works we have observed significant differences in the uvr sensibility of the strains, with the gramnegative uvps being more affected that the gram-positive uvvi (hernández et al. 2006). this higher uvr resistance of gram-positive compared with gram-negative bacteria has also been reported by other authors (fernandez zenoff et al. 2006). a differential response of the bacterioplankton components to uvr was also reported by other authors (joux et al. 1999; arrieta et al. 2000). the deleterious effect of uv-a on marine bacteria has previously been observed in the antarctic (booth et al. 2001; hernández et al. 2006), and in other aquatic environments (sommaruga et al. 1997). in an experiment performed in the marine antarctic water column, helbling et al. (1995) concluded that the impact of uv-a on two bacteria isolates and cbc was consistently greater than the impact of uv-b. although our results agree with the aforementioned finding under high irradiances, we did not observe such an effect for uv-a when the solar radiation was low, as in our experiment 5. also, differences between strains were evident under high irradiances: only uvvi was affected by exposure to uv-a, with the additional effect of exposure to uv-b being negligible; exposure to uv-b caused a significant additional mortality for uvps, compared with the damage caused by exposure to uv-a. under moderate or low radiation levels, uv-b not only had a significant negative effect, but this negative effect was greater than that of uv-a. this effect was similar for both of the strains studied. a comparable situation seems to occur at a depth of 3 m under high levels of surface irradiance, where uv-b also had the greatest effect. taking into account that cloudy days and moderate to low irradiance are by far the most frequent conditions in antarctica (hoyer et al. 2001), this differential effect of uv-b could be the main reason for the damage to bacterioplankton, particularly during spring and early summer, when the ozone hole is largest. although the water column is not a static system, and the vertical mixing could homogenize the microbial components from different depths, our results suggest a different situation. as observed in experiment 6, the cbc from the surface showed a higher resistance level to uvr than the cbc from depths of 10 and 30 m. when the uv-b dose was only a half of that registered during experiment 6, only the cbc from a depth of 30 m was affected, thereby confirming the lesser degree of adaptation of this cbc to the surface uvr. two main features dominate the hydrological structure of the water column in potter cove during spring and summer. on one hand the water column develops a strong pycnocline at a depth of ca. 5–10 m, which to some extent isolates the surface waters from deeper ones. this pycnocline results from an intense freshwater input from the land. on the other hand, the strong winds (wind uv effect on antarctic bacteria e.a. hernández et al. polar research 28 2009 390–398 © 2009 the authors396 speed > 4 m s-1) that characterize this area periodically cause the breakdown of this structure, homogenizing the water column (schloss & ferreyra 2002; schloss et al. 2002). our experiments performed with the natural cbc from depths of 0, 10 and 30 m reflect the adaptation of the community to the first scenario, i.e., a well-stratified water column. the different response shown by the surface bacterial community compared with cbc from a depth of 30 m reinforce the assumption that the pycnocline could be acting as a threshold, partially separating the microbial communities present below and above the pycnocline. however, static incubations of the natural community from surface waters at depths of 0 and 1 m resulted in a significant loss of viability, suggesting that such adaptation may not be enough to cope with the damaging effects of uvr. these results suggest that in sites such as potter cove, where high levels of spm greatly reduce the penetration of uvr, vertical mixing is one of the main factors in reducing the loss of viability caused by surface uvr. however, further studies simulating in situ vertical mixing are necessary to feed models to assess the real effects of these radiations on the bacterioplankton community of antarctic coastal waters. acknowledgements we thank oscar gonzalez and leonardo cantoni for technical assistance, and the alfred wegener institute for providing the uv-b data and laboratory facilities. this research was supported in part by the instituto antártico argentino picta 10 grant. references abele d., ferreyra g.a. & schloss i.r. 1999. h2o2 accumulation from photochemical production and atmospheric wet deposition in antarctic off-shore waters of potter cove, king george island, south shetland islands. antarctic science 11, 131–139. arrieta j.m., weinbauer m.g. & herndl g.j. 2000. interspecific variability in sensitivity to uv radiation and subsequent recovery in selected isolates of marine bacteria. applied and environmental microbiology 66, 1468–1473. boelen p., vernet m.j.w. & buma a.g.j. 2001. accumulation and removal of uvbr-induced dna damage in marine tropical plankton subjected to mixed and simulated non-mixed conditions. aquatic microbial ecology 24, 265–274. booth m.g., hutchinson l.a., brumsted m., aas p., coffin r.b., downer jr r.c., kelley c.a., maille lyons m., pakulski j.d., holder sandvik s.l., jeffrey w.h. & miller r.v. 2001. quantification of reca gene expression as an indicator of repair potential in marine bacterioplankton communities of antarctica. aquatic microbial ecology 24, 51–59. ferreyra g.a., schloss i.r., mercuri g., ferreyra l. & richter k. 2008. the potential ecological significance of dissolved and particulate matter in the water column of potter cove, king george island (isla 25 de mayo), south shetland islands. in c. wiencke et al. (eds.): synopsis of research performed at the dallmann laboratory and jubany station (antarctica). reports on polar research 571, 47–58. fernandez zenoff v., heredia j., ferrero m., siñeriz f. & farias m.a. 2006. diverse uv-b resistance of culturable bacterial community from high-altitude wetland water. current microbiology 52, 359–362. frette l., johnsen k., jørgensen n., nybroe o. & kroer n. 2004. functional characteristics of culturable bacterioplankton from marine and estuarine environments. international microbiology 7, 219–227. gustavson k., garde k., wängberg s.a. & selmer j.s. 2000. influence of uv-b radiation on bacterial activity in coastal waters. journal of plankton research 22, 1501–1511. hapter r., wozniak b. & dobrowolski k. 1983. primary production in ezcurra inlet during the antarctic summer of 1977/78. oceanologia 15, 175–184. helbling e.w., marguet f.r., villafañe v.e. & holm-hansen o. 1995. bacterioplankton viability in antarctic waters as affected by solar ultraviolet radiation. marine ecology progress series 126, 293–298. hernández e.a., ferreyra g.a. & mac cormack w.p. 2004. effect of solar radiation and the subsequent dark periods on two newly isolated antarctic marine bacteria. polar research 23, 67–77. hernández e.a., ferreyra g.a. & mac cormack w.p. 2006. response of two antarctic marine bacteria to different solar uv radiation wavelengths. antarctic science 18, 205–212. hoyer k., karsten u., sawall t. & wiencke c. 2001. photoprotective substances in antarctic macroalgae and their variation with respect to depth distribution, different tissues and developmental stages. marine ecology progress series 211, 117–129. jeffrey w. h., pledger r.j., aas p., hager s., coffin r.b., von haven r. & mitchell d.l. 1996. diel and depth profiles of dna photodamage in bacterioplankton exposed to ambient solar ultraviolet radiation. marine ecology progress series 137, 283–291. joux f., jeffrey w.h, lebaron p. & mitchell d.l. 1999. marine bacterial isolates display diverse responses to uv-b radiation. applied environmental microbiology 65, 3820–3827. karentz d. & lutze l.h. 1990. evaluation of biologically harmful ultraviolet radiation in antarctica with a biological dosimeter designed for aquatic environments. limnology oceanography 35, 549–561. klöser h., ferreyra g., schloss i.r., mercuri g., laturnus f. & curtosi a. 1994. a hydrography of potter cove, a small fiord-like inlet on king geoge island, south shetland. estuarine coastal shelf science 38, 523–537. uv effect on antarctic bacteriae.a. hernández et al. polar research 28 2009 390–398 © 2009 the authors 397 richter a., wuttke s. & zacher k. 2008. two years of in situ uv measurements at dallmann laboratory/jubany station. in c. wiencke et al. (eds.): synopsis of research performed at the dallmann laboratory and jubany station (antarctica). reports on polar research 571, 12–19. schloss i.r. & ferreyra g.a., 2002. primary production, light and vertical mixing in potter cove, a shallow bay in the maritime antarctic. polar biology 25, 41–48. schloss i.r., ferreyra g.a. & ruiz-pino d. 2002. phytoplankton biomass in antarctic shelf zones: a conceptual model based on potter cove, king george island. journal of marine systems 36, 129–143. schloss i.r., klöser h., ferreyra g.a., mercuri g. & pinola e. 1997. factors governing phytoplankton and particulate matter variation in potter cove, king george island, antartica. in b. battaglia et al. (eds.): antarctic communities. pp. 135–141. cambridge: cambridge university press. sherr b., sherr e. & del giorgio p. 2001. enumeration of total and highly active bacteria. in j.h. paul (ed.): methods in microbiology. vol. 30. marine microbiology. pp. 129–159. london: academic press. smith r.c. & baker k.s. 1979. penetration of uv-b and biologically effective dose-rates in natural waters. photochemistry and photobiology 29, 311–323. sommaruga r., oberleiter a., herndl g.j. & psenner r. 1997. inhibitory effect of solar radiation on thymidine and leucine incorporation by freshwater and marine bacterioplankton. applied environmental microbiology 63, 4178–4184. staehelin j., harris n.r.p., appenzeller c. & ebenhard j. 2001. ozone trends: a review. reviews of geophysics 39, 231–290. tedetti m. & sempéré r. 2006. penetration of ultraviolet radiation in the marine environment. a review. photochemistry and photobiology 82, 389–397. varela l. 1998. hydrology of matias and potter creeks. reports on polar research 299, 33–39. vincent w.f. & neale p.j. 2000. mechanisms of uv damage to aquatic organisms. in s.j. de mora et al. (eds.): the effects of uv radiation in the marine environment. pp. 149–156. cambridge: cambridge university press. wilhelm s.w., jeffrey w.h., suttle c.a. & mitchell d.l. 2002. estimation of biologically damaging uv levels in marine surface waters with dna and viral dosimeters. photochemistry and photobiology 76, 268–273. uv effect on antarctic bacteria e.a. hernández et al. polar research 28 2009 390–398 © 2009 the authors398 the purple saxifrage, saxifraga oppositifolia, in svalbard: two taxa or one? anne k. brysting, tove m. gabrielsen, ove s b r l i b d m n , oddmund ytrehorn and christian b r o c h m a " brysting, a. k., gabrielsen, t. m., s ~ r l i b r l t e n , o., ytrehorn, 0. & brochmann, c. 1996: the purple saxifrage, saxifraga oppositifolia, in svalbard: two taxa or one? polar research 15(2), 93-105. several studies have demonstrated high levels of genetic (dna), ecophysiological, ecological, and morphological variation within the species purple saxifrage, saxifraga oppositifolia, in svalbard. it has recently been proposed that s. oppositifolia is represented by two conspicuously different subspecies in this archipelago: ssp. reptans, a late-flowering, prostrate ecotype of snow-protected, damp habitats, and ssp. pulvinata, an early-flowering, cushion-like ecotype of dry, wind-exposed heaths and ridges. it has also been suggested that the subspecies may be differentiated at the tetraploid and diploid levels, respectively, which would promote reproductive isolation. these hypotheses are tested by examining variation in morphology, ecology, and pollen size and stainability in 150 plants of s. oppositifolia growing in 50 vegetation samples at four sites in the kongsfjorden area. although analyses of the various data sets demonstrated the large variation within the species, the material could not be separated into distinct groups. the morphological variation was continuous along local ecological gradients. the pollen grains were fully stainable and the pollen diameter data showed a unimodal distribution, suggesting that the plants analysed represent only one ploidal level. these results reject a hypothesis that the morphologically intermediate plants are hybrids between two taxa at different ploidal levels. thus, the conspicuous variation in s. oppositifolia in svalbard probably results from local, in situ ecoclinal differentiation. although this variation clearly is wifhout taxonomic significance, it is important in the broader context of arctic conservation biology and the potential impact of global warming on arctic vegetation. anne k. brysting, rove m. gabrielsen, oddmund ytrehorn and christian brochmann, botanical garden and museum, university of oslo, trondheimsveien 238, n-0562 oslo, norway; ove s@rlibriten, department of biology, division of zoology, university of oslo, p.o. box 1050 blindern, n-0316 oslo, norway. introduction it has been shown recently that, although fewer in number than in more southern areas, many arctic plants possess extraordinary high levels of varia tion. high levels of intraspecific variation in arctic plants have been documented in their ecological traits (mcgraw & antonovics 1983; mcgraw 1995a, b), ecophysiology and morphology (craw ford et al. 1993), and molecular genetics (broch mann et al. 1992a, b, c; haraldsen & wesenberg 1993; nordal & iversen 1993; gabrielsen et al. 1995; hagen et al. 1995; tollefsrud et al. 1995; bauert 1996; brysting et al. in press). for polyploid species, which constitute the majority of arctic floras, use of a wide species concept is often necessary because many such species are composed of races of different hybrid origins that bridge the morphological discontinuities origin ally found between their diploid progenitors (brochmann 1992b, 1995a, b). this type of evolution is probably associated with the turbulent climatic history of arctic areas, with repeated glaciations/deglaciations, massive plant migra tions, and frequent hybridisation. in diploid arctic species, high levels of variation may be caused by differential selection along gradients in snow cover and duration of the growth season. such factors vary considerably over short distances in the treeless arctic and alpine areas, and this is probably the main reason for the ecotypic differentiation observed in the arctic diploid dryas octopetala (mcgraw & antonovics 1983; mcgraw 1995b). the high level of intraspecific variation in arctic plants has important implications for arctic conservation biology. it is widely accepted that genetic variation and ecotypic differentiation is necessary for the long-term persistence of a species, which is of particular relevance today with regard to potential global warming (craw ford et al. 1993; mcgraw 1995b). it is paradoxi 94 a. k . brysting et al. cal, however, that traditional conservation biology focuses on taxon numbers and rare taxa rather than on the genetic diversity occurring within widely defined, widespread taxa, which probably is a better approach to conserving arctic bio diversity. the purple saxifrage, saxifraga oppositifolia l., is a variable species with wide circumpolar distribution, extending also into the higher mountains southwards in europe, asia, and north america (hultbn & fries 1986). it is a long-lived perennial with opposite, small leaves and con spicuous, pink or purple flowers appearing soon after snow-melt. although this species, in likeness with most other arctic species, is self-compatible, it strongly depends on insect pollination for seed set (stenstrom & molau 1992). the plants grow in a wide range of habitats in the arctic, including moist snow beds, heaths, dry ridges, and barren, recently unglaciated areas. the broad morphological variation within the species has been noted by many scientists, and various attempts have been made to split it into several taxa (see e.g., hayek 1905). the most recent taxonomic treatment of the intraspecific variation in s. oppositifolia is that of webb & gornall (1989), who closely follow engler & irmscher (1919). webb & gornall (1989) recog nise one widely distributed and morphologically variable subspecies, ssp. oppositifolia (the only subspecies they recognise in the european arctic), four subspecies endemic to the central and southern european mountains, and two additional subspecies occurring in the north american arctic (and probably across the beringia into eastern asia (hultbn & fries 1986). the species also varies in chromosome number. most populations investigated are diploid (2n = 26), but several tetraploid (2n = 52) popula tions have been reported from arctic areas in europe, asia, and north america (hedberg 1967; johnson & packer 1968; lave & liive 1975). two chromosome counts, both tetraploid, have been published for s. oppositifolia in svalbard, one from the @fjorden area (flovik 1940) and one from the ny alesund area (chapman 1995). all studies from the rest of northern europe have reported a diploid number (e.g., skovsted 1934; e v e & lave 1956). to what extent the chromosomal variation in s. oppositifolia is correlated with the morphological differentiation of the species is unknown. recently, there has been particular focus on the variation within s. oppositifolia in svalbard. this focus has been accentuated by the publication of a colo;r photograph of a cushion-formed plant from ny alesund on the front cover of the journal molecular ecology (abbott et al. 1995), and by the recognition of two ecologically and morpho logically divergent subspecies, one cushion formed and one prostrate, in the new edition of rbnning’s svalbards flora (rbnning 1996). this variation in growth form within s. oppositifolia in svalbard was already reported by anderson & hesselman (1900). recent studies have demon strated that there not only is large morphological and ecological variation in s. oppositifolia in the archipelago, but that the species also shows large variation in dna markers (abbott et al. 1995; gabrielsen et al. 1995, gabrielsen 1996) and ecophysiological traits (crawford et al. 1993, 1994; crawford & abbott 1994). the different growth forms observed in s. oppositifolia in svalbard have also been suggested to be correlated with other characteristics (craw ford et al. 1993; rbnning 1996; elven & elvebakk 1996). the prostrate plants grow in snow protected, damp habitats and have high photo synthetic rates, distant leaves with marginal cilia, and open flowers with narrow, non-overlapping petals, whereas the cushion-formed plants grow on dry, wind-exposed ridges and have low photosynthetic rates, dense, overlapping leaves entirely or mostly without cilia, and urn-shaped flowers with broad, overlapping petals. in the new edition of rbnning’s svalbards flora ( r ~ n n i n g 1996), the prostrate plants are referred to as s. oppositifolia ssp. reptans (anderss. & hesselm.) rbnning, and the cushion-formed plants are referred to as s. oppositifolia ssp. pulvinata (anderss. & hesselm.) rbnning. although only tetraploid plants of s. oppositifolia have been recorded in svalbard, it has been suggested that both diploid and tetraploid plants are present and that the difference in ploidal level may be correlated with growth form (crawford et al. 1993; cf. also liive & e v e 1951, 1975). the aim of the present study was to determine if it is reasonable to divide s. oppositifolia in svalbard into two ecologically, morphologically, and possibly also chromosomally, distinct taxa, or if the variation merely is ecoclinal, representing continuous morphological variation along local ecological gradients. four different data sets were produced to answer this question: (1) ecological the purple saxifrage 95 parameters were measured or estimated to detect possible habitat differences correlated with growth form differences; (2) macro-morphologi cal characters were measured in field-collected plants to detect any possible characters correlated with ecological traits and/or growth form differ ences; (3) pollen size was measured to reveal possible reproductive barriers owing to ploidal differences between growth forms (see broch mann 1992a); and (4) pollen stainability was estimated to reveal if there was lowered fertility in morphologically intermediate plants, if such plants (potential hybrids) were detected. materials and methods ecological data a total of 50 vegetation samples, each of 1 mz, were analysed at four sites in the kongsfjorden area where the postulated subspecies grow in close geographic proximity: (1) b r ~ g g e r h a l v ~ y a , stuphallet, utm vh 28-29 68-69, 12 samples (nos. 22-33, cf. table 2); (2) brbggerhalvoya, nw of bayelva, utm vh 3265, 16 samples (nos. 4-19); (3) brgggerhalvbya, s of ny h e s u n d , utm vh 34-35 63, 14 samples (nos. 1-3,20, 21, 42-50); and (4) blomstrandoya, london, utm vh 3768, 8 samples (nos. 34-41). the vegetation samples were subjectively selected so that the samples at each site covered the range of variation observed in the vegetation where s. oppositifolia occurred, and so that at least one plant of s. oppositifolia occurred within each sample. in each sample, the percentage cover of each vascular plant species (nomenclature follows elven 1994) and the total cover of the vegetation, vascular plants, cryptogams, bryophytes, lichens, stones, and bare ground were recorded. in addition, the humidity conditions (1 = dry, 2 = in termediate, 3 = damp, 4 = moist) and degree of wind exposure (1 = protected, 2 = intermediate, 3 = exposed) were subjectively estimated from the topography and a general impression of the sample site. the aspect and slope (angle of inclination) were measured for each sample. the vegetation samples and the surrounding areas were classified into five vegetation types following brattbakk (1981): (1) dryas octopetala heaths and ridges, (2) luzula arcuata-lichen heaths, (3) s. oppositifolia-lichen heaths, (4) talus slope vegetation, and (5) deschampsia alpina snowbeds. morphological and pollen stainability data a total of 150 plants of s. oppositifolia occurred within the vegetation samples. in the field, each plant was tentatively classified after growth form as typically prostrate or typically cushion-formed. it was, however, difficult to classify all plants into these two groups, and several plants were tentatively grouped as “intermediates”. thirteen macroscopic morphological characters were scored for each plant. seven characters were quantitative, three characters were qualitative, and table 1 . macroscopic characters used in morphometric analyses of saxifraga oppositifolia. five measurements were made of each character for each plant, and the median was used in further analyses. characters included in the pco analysis are indicated. measurements in mm. character note pco internode length leaf width leaf length leaf index no. of leaf cilia no. of leaf cilia pr. petal width petal length petal index petal apex overlap of petals flower shape flower diameter mm the five longest internodes selected in each plant maximum width leaf widthileaf length number of cilia along one side of the leaf number of ciliafleaf length maximum width petal width/petal length 1 rounded, 2 intermediate, 3 acute 1 non-overlapping, 2 tangent, 3 overlapping 1 flattened, 2 intermediate, 3 urn-shaped from petal apex to petal apex 96 a. k. brysting et al. table 2. floristic composition, frequency, and percentage cover of vascular plants in 50 vegetation samples including saxifraga oppositifolia. vegetation type no. &talus slope vegetation, no. 5-deschampsia alpina snowbed. two species groups in saxifraga were scored collectively because of the early developmental stage of the plants (s. cernua/hyperborea/rivuluris and s. nivalis/ tenuis). 1 dryas octopetala ridgeheath 2 luzula arcuata lichen heath speciedsample no. 10 11 12 13 17 18 25 26 28 30 33 38 freq. 1 2 3 42 43 44 45 46 47 48 49 50 freq. saxifiaga oppositifolia bistorta vivipara cardamine bellidifolia carex rupestris cerastium arcticum cerastium regelii cochlearia groenlandica deschampsia alpina draba lactea dryas octopetala equisetum scirpoides juncus biglumis lwula arctica lwula arcuata oxyria digyna pecicularis hirsuta poa alpina sagina nivalu salk polaris saxifraga cern.lhyp.lriv. saxijiaga cespitosa saxifraga nivalisltenuis silene acaulis silene uralensis 2 4 2 3 4 2 1 0 5 0 8 1 0 1 5 1 0 1 . 0 5 0 5 2 1 0 5 4 3 2 5 5 5 4 5 1 . 0 1 1 1 1 1 1 7 2 2 1 1 0 . 9 i 1 0 . 2 0.2 1 1 0 . 2 1 1 _ _ _ _ _ 0.2 _ _ _ _ _ _ _ 0.0 1 0 . 5 1 1 1 1 1 1 1 1 0 . 7 _ _ 0.2 _ _ _ _ _ _ 1 _ _ _ _ 0.1 _ 0 . 0 1 1 1 0 . 3 _ _ 0 . 1 1 1 1 0 . 3 _ _ 0.2 1 1 1 0 . 3 4 5 0.6 _ _ _ _ _ _ _ _ 0.0 _ _ 0.0 _ _ _ _ _ _ _ _ _ _ 0.0 _ _ 0.2 _ _ _ _ _ _ 0.0 o . o 1 _ _ _ i 0.2 _ _ 0.2 5 3 1 1 5 3 1 2 7 3 3 0 . 9 _ _ 0.0 1 1 1 1 1 1 1 1 1 0 . 8 _ _ 0 . 2 1 1 1 1 1 0 . 4 1 0 . 2 1 1 1 0 . 1 1 1 1 1 o o . 3 1 1 0 . 8 1 6 1 4 1 5 2 5 1 5 3 5 5 0 . 8 1 0 . 3 1 1 1 3 1 1 1 1 0 . 7 _ _ 0.3 2 1 1 1 1 1 1 1 1 0 3 _ _ 0.1 1 1 _ i 0.3 _ _ 0.1 _ _ 0.0 _ _ 0.3 _ _ _ _ 0.0 additional species (occurring in 1-3 samples only): draba alpina, d. corymbosa, d. oxycarpa, d. subcapitatu, d. micropetala, equisetum arvense, e . variegatum, minuartia biflora, papaver dahlianum, saxifraga aizoides, s. hieracifolia, stellaria longipes, carew misandra, phippsia sp. three characters were ratios between quantitative characters (table 1). when possible, five mea surements were made of each character for each plant, and the median of these five measurements was used in further analyses. the leaf characters were measured on the five longest shoots, on a leaf positioned 1 cm below the shoot apex. the flower characters were measured on the five best developed flowers on each plant. pollen size and stainability were measured in 36 plants, 12 plants from each of the three tentative growth form groups (typically prostrate, typically cushion-formed, or "intermediate"). pollen grains were stained in cotton blue in lactophenol (radford et al. 1974). the largest diameter of ten subjectively selected pollen grains of each plant was measured using a light microscope. pollen fertility was estimated by counting the percentage of well-stained and regularly shaped pollen grains in a sample of 200 grains per plant. herbarium vouchers of 20 representative speci mens of s. oppositifolia, selected among the 150 plants analysed, have been deposited at the botanical museum, university of oslo. multivariate analyses and statistics descriptive statistics and correlations were per formed using spss for windows (norusis 1993). the ecological data were analysed using de trended correspondence analysis (dca; cf. hill & gauch 1980) based on floristic composition of the vegetation samples. the canoco program (braak 1987) was used for these computations with standard parameter choice except that rare species were downweighted according to eilertsen et al. (1990). principal coordinate analysis (pco; gower 1966, 1967) and nonmetric multidimen sional scaling (nmds; kruskal 1964) were performed using ntsys-pc (rohlf 1990) based on seven morphological characters, excluding qualitative multistate characters and characters with overlapping information (table 1). the quantitative, continuous morphological characters were in-transformed before analyses to eliminate the purple saxifrage 97 table 2. continued 3 saxifraga oppsififoolia lichen heath 4 5 total 4 5 6 7 8 9 14 15 16 19 20 21 22 24 29 31 32 34 35 36 37 39 40 41 freq. 23 27 freq. 5 5 2 6 3 8 50 7 20 5 10 3 3 10 25 5 10 25 2 8 10 15 30 15 1.0 10 30 0.1 1 1 1 2 1 1 1 1 1 5 1 1 1 5 2 1 1 1 1 2 1 0 . 8 3 1 0 . 1 the effect of size (cf. brochmann 1987). all morphological characters were subsequently stan dardised by “ranging” (i.e., each character was scaled between 0 and 1, gower 1971), and morphological dissimilarities between plants were calculated as average manhattan distances (rohlf 1990). kendall’s z correlations (kendall 1938) were calculated for the two first pco axes, dca axis 1, the morphological characters, and the ecological parameters. ecology saxifraga oppositifolia showed a wide ecological amplitude in the kongsfjorden area. the species occurred in a wide range of habitats varying from dry, wind-exposed, almost unvegetated ridges and slopes, via snow-protected, damp, densely vege tated heaths, to moist, densely vegetated snow beds. a total of 38 vascular plant species was recorded in the 50 vegetation samples analysed (table 2). most samples were classified into three vegetation types, i.e., dryas octopetala heaths and ridges (12 samples), luzula arcuata-lichen heaths (12 samples), and s. oppositifolia-lichen heaths (24 samples; tables 2 and 3). one sample was classified as talus slope vegetation, and one as deschampsia alpina snowbed. the percentage cover of s. oppositifolia in each vegetation sample varied between 2% and 50%, and the cover of the species varied considerably within as well as between the main vegetation types (table 2). the most conspicuously cushion-forming plants of s. oppositifolia were found at the driest, uppermost dryas ridges. the dryas octopetala vegetation type was, on average, the driest and most wind-exposed one among the main vegeta tion types (mean humidity 1.8; mean wind exposure 2.7), but the degree of humidity and wind exposure varied within this vegetation type along a gradient from ridges to slopes and heaths. the total vegetation cover (mean 52%) as well as the cover of bryophytes and lichens were, on \d 0 3 p r t ab le 3 . e co lo gi ca l p ar am et er s sc or ed in 5 0 ve ge ta tio n sa m pl es w ith s ax ifr ag a op po si tif oo lia , c la ss if ie d in to v eg et at io n ty pe s fo llo w in g b ra ttb ak k (1 98 1) . b 0 > h um id ity w in d ex po su re sl op e (a ng le o f t ot al v eg et at io n v as cu la r pl an t n o. o f 1 d ry , 4 m oi st 1 p ro te ct ed , 3 e xp os ed in cl in at io n) co ve r (% ) co ve r (% ) v eg et at io n ty pe sa m pl es m ea n sd m in m ax m ea n sd rn in m ax m ea n sd m in rn ax m ea n sd rn in m ax m ea n sd m in m ax d ry as o ct op et al a ri dg eh ea th 12 1. 8 0. 87 1 3 2. 7 0. 49 2 3 14 16 .2 0 60 52 35 .5 5 95 26 25 .8 3 70 l uz ul a ar cu at a li ch en h ea th 12 2. 3 0. 49 2 3 2. 0 0. 00 2 2 1 1. 8 0 5 82 23 .0 35 10 0 22 17 .3 4 60 sa xi fr ag a op po si tif ol ia li ch en h ea th 24 2. 8 0. 82 2 4 1. 8 0. 51 1 3 9 10 .2 0 40 83 20 .9 15 10 0 21 15 .7 3 55 t al us s lo pe v eg et at io n 1 3. 0 2. 0 o 5 0 z d es ch am ps ia a lp in a sn ow be d 1 4. 0 2. 0 o 9 5 4 5 v eg et at io n ty pe ~ ~ c ry pt og am b ry op hy te l ic he n st on e b ar e gr ou nd n o. o f co ve r (% ) co ve r (% ) co ve r (% ) co ve r (% ) co ve r (a ) sa m pl es m ea n sd rn in rn ax m ea n sd rn in m ax m ea n sd rn in m ax m ea n sd m in m ax m ea n sd mi n m ax ~ d ty as o ct op et al a ri dg eh ea th 12 31 28 .5 1 85 21 25 .9 1 75 11 13 .5 1 45 36 35 .9 1 95 14 25 .8 0 92 l uz ul a ar cu at a lic he n he at h 12 75 21 .7 34 98 60 20 .8 33 95 15 13 .9 1 50 13 16 .6 0 40 5 9. 1 0 30 sa xi fr ag a op po si tif ol ia li ch en h ea th 24 71 21 .5 10 99 44 22 .1 10 98 27 20 .6 1 90 10 13 .6 0 50 8 16 .1 0 70 t al us s lo pe v eg et at io n 1 z 5 2 0 2 5 z d es ch am ps ia a lp in a sn ow be d 1 5 0 3 5 1 5 5 o the purple saxifrage 99 table 4. descriptive statistics of macroscopic morphological characters analysed in saxifraga oppositifolia, based on the median of five measurements per plant. see table 1 for explanation of characters. character no. of plants mean s d min max lnternode length (mm) leaf width (mm) leaf length (mm) leaf index no. of leaf cilia no. of leaf cilia pr. mm petal width (mm) petal length (mm) petal index petal apex (1 rounded, 3 acute) overlap of petals (1 non-overlapping, 3 overlapping) flower shape (1 flattened, 3 urn-shaped) flower diameter (mm) average, lowest in the dryas vegetation type. the uppermost ridges were almost unvegetated (cover 5%), whereas the most humid dryas heaths were densely vegetated (cover up to 95%). the vascular plant species most frequently observed in the dryas vegetation type, except for the only dominating species dryas octopetala and s. oppositijolia, were bistorta vivipara, cerastium arcticum, and salk polaris (table 2). the most prostrate, creeping plants of s . oppositijolia were found in the most humid parts of the lichen heaths. the two lichen heath vegetation types were fairly similar except for quantitative differences in the occurrences of some species, in particular s . oppositijolia, luzula arcuata, bistorta vivipara, and oxyria digyna, and in relative importance of bryophytes versus lichens (tables 2 and 3). the lichen heaths were, on the average, densely vegetated (mean cover 82-83%), but had about the same cover of vascular plants as the dryas vegetation type 146 146 146 146 145 145 132 132 132 131 132 132 132 2.8 1.9 3.3 0.57 8.6 2.6 4.2 6.8 0.60 1.6 2.0 1.9 11.3 1.66 0.26 0.45 0.06 2.0 0.58 1.15 1.07 0.11 0.5 0.6 0.6 2.29 0.3 8.1 1.3 2.7 2.1 4.5 0.44 0.73 4 15 1.3 4.2 1.5 8.6 4.6 10.1 0.33 0.85 1 3 1 3 1 3 7 18 (means 21-22% and 26%, respectively). the cryptogam layer covered, on the average, 71-75% in the lichen heaths, versus 31% in the dryas vegetation. the dca analysis based on the floristic composition of the 50 vegetation samples did not result in an interpretable pattern, probably caused by the species-poor samples with con siderable overlap in species content, and this analysis is therefore not shown. among the ecological parameters, only cryptogam cover and bryophyte cover were significantly (p < 0.05) correlated with dca axis 1. because no other parameters (e.g., humidity or total vegetation cover) were significantly correlated with dca axis 1, these two parameters did not per se provide any meaningful ecological interpretation of the dca axis. dca axis 1 may nevertheless represent a humidity gradient. this might have been verified by a more accurate measure of humidity. several ecological parameters were, however, fig. 1 . variation in internode length in saxifraga oppositifolia from the kongsfjorden area in svalbard. n = 150 plants. 100 a . k. brysting et al. 0.1 c.l v) 3 0.0 - o cushion-formed a intermediate -0.1 -. a a prostrate a pco axis 1 significantly correlated with individual morpho logical traits of s . oppositifolia as well as the pco axes (see below). macromorphology the plants analysed showed conspicuous variation in most individual morphological characters (table 4). however, all quantitative characters showed a unimodal distribution, most distinctly so, and it was thus not possible to separate the material into two or more groups based on any individual characters. internode length, the character most closely associated with the growth form of the plants, varied from 0.3 mm (i.e., 3.3 leaves per mm of the stem) in the most cushion-formed plants to 8.1 mm (i.e., 0.1 leaf per mm of the stem) in the most prostrate plants, with an average of 2.8 mm for the 146 plants measured for this character. as for all morphological characters, the internode length showed a unimodal distribution (fig. 1). the leaves varied considerably in size and shape. the leaf length varied from 2.1 mm to 4.5 mm (mean 3.3 mm), the leaf width varied from 1.3 mm to 2.7 mm (mean 1.9 mm), and the leaf shape varied from narrowly to widely elliptic (mean leaf index 0.57). leaf ciliation varied less than expected. all plants had ciliated leaves, varying from 1.3 to 4.2 cilia per mm of the leaf margin. the variation in floral characters was particu larly conspicuous. the petals varied nearly six fold in width, from very narrow (1.5 mm) to very broad (8.6 mm), and more than two-fold in length (4.6-10.1 mm). the petals also varied consider fig. 2. pco analysis (axes 1 and 2) of 146 plants of saxifiaga oppositifolia from the kongsfjorden area in svalbard based on seven morphological characters. the classification into growth forms (cushion-formed, intermediate, or prostrate) was not included prior to the analysis, but subsequently assigned to the plants subjected to the pco analysis. ably in shape, from very long, narrow, and non overlapping (petal index 0.33) to nearly as broad as long and overlapping (petal index 0.85), and with an apex varying from rounded to acute. the shape of open flowers varied from flattened to distinctly urn-shaped. nor did the pco analysis result in any distinct grouping of the plants, although the analysis revealed that there was a mainly one-dimensional, simple structure in the total morphological data set (fig. 2). the first pco axis had a high eigenvalue (1.40) and accounted for 78.3% of the total variance in the morphological data, and the first two pco axes accounted for 95% of the variance. the result of the nmds analysis (stress 0.22; not shown) was largely similar to that of the pco analysis. most of the morphological characters were signifiantly correlated with pco axis 1 (see also below; cf. table 5). internode length was most strongly correlated, and negatively so (7) = -0.73, p < 0.001), indicating that the most prostrate plants (i.e., those with long internodes) had low values along pco axis 1 and the most cushion formed plants (i.e., those with short internodes) had high values along pco axis 1. the tentative field classification of the plants after growth form as typically prostrate, “intermediate”, or typically cushion-formed was superimposed on the pco diagram (fig. 2; note that this character was not included prior to the pco analysis). most of the plants classified as typically prostrate had low values (-0.3 to 0) along pco axis 1, whereas most of the plants classified as typically cushion formed had higher values (0 to 0.2), indicating that this subjective growth-form classification the purple saxifrage 101 agreed with the exact measurements of internode lengths. notably, neither the growth-form classi fication nor the internode analysis resulted in distinct groups in the material; rather, the scores were distributed continuously along the two pco axes. b 8. pollen size and stainability the pollen diameter in individual plants varied from 20.0 to 32.2 pm, and the mean pollen diameter for the 36 plants analysed was 25.0 pm (sd 2.6). the pollen diameter showed a distinct unimodal distribution (fig. 3). all plants except one had more than 80% stainable pollen (mean 92%, sd 8%, min 60%, max 95%; n = 36 plants). correlations among ecological traits, morphological traits, and pco axes several of the individual traits were significantly correlated (table 5). among the ecological traits, humidity, vegetation cover, vascular plant cover, cryptogam cover, and bryophyte cover were positively correlated (p < 0.01). these traits were negatively correlated (p < 0.01) with stone cover, bare ground cover, and wind exposure. among the morphological characters, leaf width, flower diameter, petal length, petal width, and petal index were positively correlated (p < 0.01). internode length was positively correlated (p < 0.05) with humidity, growth form, flower diameter, petal length, petal width, petal index, leaf length, and leaf width. the number of leaf cilia per mm, petal apex, and wind exposure were negatively correlated with internode length. growth form was positively correlated (p < 0.05) with flower diameter, leaf length, leaf width, leaf index, vascular plant cover, lichen cover, and humidity, and negatively correlated 0, < 0.05) with number of leaf cilia per mm, petal apex, and wind exposure. internode length and number of leaf cilia per mm were most strongly correlated with pco axis 1 (table 5 ) . internode length was negatively correlated, and the number of leaf cilia per mm was positively correlated with pco axis 1. floral characters and leaf width were negatively corre lated with pco axis 1. except for internode length, similar, but weaker correlations were found for pco axis 2. the significant correlations found for pco axis 2 were leaf width (t) = -0.13, 0.01 < p < 0.05), number of leaf cilia pr. mm 102 a . k. bysting et al. fig. 3. variation in pollen diameter in saxifraga oppositifolia from the kongsfjorden area in svalbard. n = 36 plants (360 grains). (z) = 0.24, p < 0.001), petal width (z) = -0.32, p < 0.001), petal index (t) = -0.28, p < 0.001), and flower diameter (z) = -0.25, p < 0.001). the median pollen diameter was positively correlated with internode length (z) = 0.53, p < 0.001) and growth form (z)=o.53, p < 0.001), and negatively correlated with pco axis 1 (t) = -0.58, p < 0.001). thus, the prostrate plants had larger pollen grains, longer internodes, fewer leaf cilia, larger leaves, larger flowers, larger, broader, and more rounded petals and occurred in wetter and less windy habitats than the cushion-formed plants. discussion neither the individual morphological characters nor the pco analysis indicate that it is possible to divide the plant material into two distinct groups, as would be expected if the two growth forms of s. oppositifolia deserve status as separate taxa. most characters vary continuously and show unimodal distributions. the growth form was not included as a character prior to the pco analysis, but when the plants subsequently were labeled according to the tentative growth form classification, the three groups, prostrate, “inter mediates” and cushion-formed, showed a contin uous, overlapping distribution along pco axis 1. in particular, the unimodal distribution of inter node length (fig. l), a character which could be quantified exactly and which is closely associated with growth form, and the strong correlation between this character and pco axis 1 (table 5 ) strongly support the hypothesis that s. oppositifo lia is represented by a single, but variable, taxon in svalbard. several morphological traits besides internode length have been suggested to be diagnostic characters distinguishing between the two pro posed subspecies of s. oppositifolia (crawford et al. 1993; elven & elvebakk 1996; r ~ n n i n g 1996): the prostrate growth form has been suggested to be correlated with occurrence of marginal leaf cilia, open flowers, and narrow, non-overlapping petals, whereas the cushion-like growth form has been suggested to be correlated with absence of leaf cilia, urn-shaped flowers, and broad, over lapping petals. our results demonstrate, however, (1) that the number of cilia is negatively correlated with internode length (i.e., prostrate plants are more sparsely ciliated than cushion formed plants), (2) that petal width is positively correlated with internode length (lee, prostrate plants have broader petals than cushion-formed plants), and (3) that neither flower shape nor overlap of petals are correlated with internode length. we have thus shown that none of the cilia and floral characters separate the two growth forms in the way proposed by crawford et al. (1993), elven & elvebakk (1996), and r ~ n n i n g (1996). it is well known that the pollen size may be useful to discriminate between different ploidal levels in plants, in particular between closely related populations at low ploidal levels (ehren dorfer 1964; ugborogho 1973; brochmann 1992a). the stainable (and thus probably fully fertile) pollen grains and the unimodal distribution of pollen diameter observed in this study suggest that the plants analysed of s. oppositifolia represent a single ploidal level (diploid or the purple saxifrage 103 in conclusion, the present study clearly demon strates the high levels of morphological and ecological variation within s. oppositifolia in svalbard, but gives no support for maintaining the two growth forms as the separate subspecies reptans and pulvinata as proposed by ronning (1996). it seems rather most reasonable to refer all of the populations of s. oppositifolia occurring in svalbard to the widespread and variable, typical subspecies oppositifolia, in agreement with webb & gornall (1989), who note that this subspecies is “usually fairly lax in growth (except in very exposed situations)” (p. 106). the differentiation within s. oppositifolia in svalbard is clearly of no taxonomic significance, but probably caused by local ecoclinal evolution occurring independently in different sites and geographic areas. the close geographic proximity of the extreme forms, a considerable overlap in flowering time, and the existence of many, fully fertile plants that cannot easily be classified as either prostrate or cushion formed suggest that the plants at each site represent single panmictic populations rather than different taxa evolved by sympatric sub-specia tion. genetic diversity and ecological versatility within species seem to be common phenomena in many arctic plants, without necessarily being of taxonomic significance (mcgraw 1995; murray 1995). such variation is, however, of significance in a broader context of arctic conservation biology and the potential impact of global warming on arctic vegetation. achawledgements this study was carried out as a project during the graduate student course in arctic biology (bio 390) arranged in 1995 by the department of biology, university of oslo, in ny hesund, svalbard. we thank the norwegian polar institute !or logistic support and use of their research facilities in ny alesund. the study was partly supported by grant 101183/720 to cb from the terrestrial ecological research program in svalbard, the norwegian research council. tetraploid). because cushion-formed, “intermedi ate”, and prostrate plants were equally well represented among the investigated plants, the growth forms are thus probably not reproductively isolated by genetic barriers. notably, the plants with intermediate morphology had fully stainable pollen. this result would not have been expected if the intermediates were triploid hybrids between a diploid and a tetraploid taxon. however, without chromosome counts it is not possible to determine if the plants analysed are diploids or tetraploids. the significant correlations obtained between some of the ecological parameters and internode length as well as growth form indicate that the cushion-formed plants are most common on dry, wind-exposed ridges, whereas the prostrate plants usually are found in less exposed and more damp habitats. this is in agreement with the observa tions by crawford et al. (1993), rbnning (1996), and elven & elvebakk (1996). the pco and correlation analyses demonstrate, however, that the morphological variation in s. oppositifolia is continuous along local ecological gradients. plants in the driest and most wind-exposed habitats have shorter internodes, smaller and more densely ciliated leaves, and smaller flowers than plants growing in successively more damp habitats. these characters probably all reflect response to drought. similar, genetically based clinal variation along local humidity gradients has recently been demonstrated in the genus franke nia, suggested to be caused by one or a few genetic factors that control organ size and are subjected to differential selection with respect to drought tolerance (brochmann et al. 1995). it is likely that the observed morphological and ecological variation in s. oppositifolia is geneti cally based, but this cannot be determined with certainty without molecular genetic data, manip ulation of environmental factors, or reciprocal transplant experiments. however, we observed that prostrate and cushion-formed plants occa sionally grow in close proximity within the same, apparently homogeneous habitat. this observation may suggest that the growth form is genetically determined, and that the different genotypes sometimes are able to disperse and establish in suboptimal habitats. notably, similar conspicuous differences in morphology and photosynthetic capacity that are genetically based have been demonstrated along similar environmental gradi ents for dryas octopetala in alaska (mcgraw & antonovics 1983; mcgraw 1995a). references abbott, r. j., chapman, h. m., crawford, r. m. m. & forbes, d. g . 1995: molecular diversity and derivations of popula tions of silene acaulis and saxifiaga oppositifolia from the high arctic and more southerly latitudes. molec. e d . 4, 199-207. andersson, g . & hesselman, h. 1900: bidrag ti1 kannedomen om spetsbergens och beeren eilands karlvaxtflora. bih. k. svenska vet.-akad. handl. 26, ill, i, 1-88. bauert, m. r. 1996: genetic diversity and ecotypic differentia tion in arctic and alpine populations of polygonurn viviparum. arct. alp. res. 28, l w 1 9 5 . 104 a . k . brysting et al. braak, c. j. f. ter 1987: canocof o r t m p r o g r a m for canonical communiry ordination by (partial)(detrended)(ca nonical) correspondence analysis, principal components analysis and redundancy analysis (version 2.1). tno inst. appl. comp. sci., stat. dept. wageningen, wageningen. brattbakk, i. 1981: br@ggerhalv@ya, svalbard. vegetasjonskart 1:10.000. k. norske vitensk. selsk. mus. bot. avd., trondheim. evaluation of some methods for hybrid ed by hybridization in argyranthemum (asteraceae). nord. j . bot. 7, 609-630. brochmann, c. 1992a: pollen and seed morphology of nordic draba (brassicaceae): phylogenetic and ecological implications. nord. j . bot. 12, 657473. brochmann, c. 1992b: polyploid evolution in arctic-alpine draba (brassicaceae). sommerf: suppl. 4 , 1-37. brochmann, c. 1995a: arktisk biodiversitet er underestimert: ny innsikt fra evolusjonsog molekylrergenetiske studier. univ. trondheim vitensk.mus. rapp. bot. ser. 1995 3, 18-20. brochmann, c. 1995b conservation biology and polyploid evolution in the arctic: insights from molecular and reproductive studies. abstract, vl international symposium iopb, “variation and evolution in arctic and alpine plants”, tromso, norway. brochmann, c., lobin, w., sunding, p. & stabbetorp, 0. 1995: parallel ecoclinal evolution and taxonomy of frankenia (frankeniaceae) in the cape verde islands, w africa. nord. j. bot. 15, 603423. brochmann, c., soltis, d. e. & soltis, p. s. 1992a: electrophoretic relationships and phylogeny of nordic polyploids in draba (brassicaceae). plant syst. evol. 182, 35-70. brochmann, c., soltis, p. s. & soltis, d. e. 1992b: multiple origins of the octoploid scandinavian endemic draba cacuminum: electrophoretic and morphological evidence. nord. j . bot. 12, 257-272. brochmann, c., soltis, p. s. & soltis, d. e. 1 9 9 2 ~ recurrent formation and polyphyly of nordic polyploids in draba (brassicaceae). amer. j . bot. 79, 673-688. brysting, a. k., elven, r. & nordal, i. in press: the hypothesis of hybrid origin of poa jemtlandica supported by morpho metric and isozyme data. nord. j. bot. chapman, h. m. 1995: p. 10 in stace, c. a. (ed.): iopb chromosome data 9. iopb newsletter 24. crawford, r. m. m. & abbott, r. j. 1994: pre-adaptation of arctic plants to climate change. botanica acta 107, 271-278. crawford, r. m. m., chapman, h. m., abbott, r. j. & balfour, j . 1993: potential impact of climatic warming on arctic vegetation. flora 188, 367-381. crawford, r. m. m., chapman, h. m. & hodge, h. 1994: anoxia tolerance in high arctic vegetation. arct. alp. res. 26, 308-312. ehrendorfer, f. 1964. notizen zur cytotaxonomie und evolu tion der gattung artemisia. &err. bot. zeitschr. 111, 84-142. eilertsen, o., 0kland, r. h., okland, t. & pedersen, 0. 1990: data manipulation and gradient length estimation in dca ordination. j . veg. sci. 1 , 261-270. elven, r. 1994. 6. utg. av lid & lid, norskflora. det norske samlaget, oslo. elven, r. & elvebakk, a. 1 9 9 6 part 1. vascular plants. pp. 9-53 in elvebakk, a. & prestrud, p. (eds.): a catalogue of svalbard plants, fungi, algae, and cyanobacteria. norsk polarinst. skr. 198. engler, h. g. a. & itmscher, e. 1919: saxifragaceae: saxifraga. das pflanzenreich 69, 449-709. flovik, k. 1940: chromosome numbers and polyploidy within the flora of spitzbergen. hereditas 26, 4 3 w o . gabrielsen, t. m. 1996: rapd variation and phylogeography of nordic populations of saxifiaga oppositifolia. cand. scient. thesis, univ. of oslo. gabrielsen, t. m., bachmann, k., jakobsen, k. s. & brochmann, c. 1995: rapd variation in an arctic-alpine, mainly diploid outbreeder: saxifraga oppositifolia. abstract, vi international symposium iopb, ‘ ‘variation and evolu tion in arctic and alpine plants”, tromsg, norway. gower, j. c. 1966: some distance properties of latent root and vector methods used i n multivariate analysis. biometrika 53, gower, 1. c. 1967: multivariate analysis and multidimensional geometry. statistician 17, 13-28. gower, j. c. 1971: a general coefficient of similarity and some of its properties. biometrics 27, 857-874. hagen, a,, schjoll, o., brochmann, c., elven, r., nordal, i. & borgen, l. 1995: genetic variation in the polyploids cerastium alpinum and c . arcticum (caryophyllaceae): morphology, isozymes and rapds. abstract, v1 interna tional symposium iopb, ‘ ‘variation and evolution in arctic and alpine plants”, tromse, norway. haraldsen, k. b. & wesenberg, j. 1993: population genetic analyses of an amphi-atlantic species: lychnis alpina (caryophyllaceae). nord. j. bot. 13, 377-387. hayek, a. 1905: monographische studien iiber die gattung saxifraga, 1. die sektion porphyrion tausch. denkschr. kaiserl. akad. wissensch., wien, 77, 61 1-709. hedberg, 0. 1967: chromosome numbers of vascular plants from arctic and subarctic north america. arkiv bot. 11, 6 , hill, m. 0. & gauch, h. g. 1980: detrended correspondence analysis: an improved ordination technique. vegetatio 42, 47-58. hulth, e. & fries, m. 1986: atlas of north european vascular plants north of the tropic of cancer. koeltz, konigstein. johnson, a. w. & packer, j. g. 1968: chromosome numbers in the flora of ogotoruk creek, n. w. alaska. bot. not. 121, 403-456. kendall, m. g. 1938: a new measure of rank correlation. biometrika 30, 81-94. kruskal, j. b. 1964: multidimensional scaling by optimizing goodness of fit to a nonmetric hypothesis. psychometrika 29, 1-27. liive, a. & e v e , d. 1951: studies on the origin of the icelandic flora. 11. saxifragaceae. svensk bot. tidskr. 45, 368-399. liive, a. & liive, d. 1956: cytotaxonomical conspectus of the icelandic flora. acta horli gotob. 20, 65-291. e v e , a. & e v e , d. 1975: cytotaxonomical atlas of the arctic flora. cramer, vaduz. mcgraw, j. b. 1995a: patterns and causes of genetic diversity in arctic plants. pp. 33-43 in chapin 111, f. s. & korner, c. (eds.): arctic and alpine biodiversity: patterns, causes and ecosystem consequences. springer, berlin. 325-338. 309-326. the purple saxifiage 105 mcgraw, j. b. 1995b: prevalence and significance of ecotypic variation in arctic and alpine plants. abstract, vi interna tional symposium iopb, ‘ ‘variation and evolution in arctic and alpine plants”, tromso, norway. mcgraw, j. b. & antonovics, j. 1983: experimental ecology of dryas octopetala ecotypes. 1. ecotypic differentiation and life cycle stages of selection. j . ecol. 71, 879-897. murray, d. f. 1995: causes of arctic plant diversity: origin and evolution. pp. 21-32 in chapin 111, f. s. & komer, c. (eds.): arctic and alpine biodiversity: patterns, causes and ecosystem consequences. springer, berlin. nordal, i. & iversen, a. p. 1993: mictic and monomorphic versus parthenogenetic and polymorphic-a comparison of two scandinavian mountain grasses. opera bot. 121, 19-27. norusis, m. j . 1993: spss for windows. base systems user’s guide. release 6.0. spss inc., chicago. radford, a. e., dickison, w. c., massey, j. r. & bell, c. r. 1974: vascularplant systematics. harper & row, new york. rohlf, f. j. 1990: ntsys-pc. numerical taxonomy and multivariate analysis system. version 1.60. exeter software, new york. ronning, 0. i. 1996: svalbards flora. ed. 3. norsk polarinstitutt, oslo. skovsted, a. 1934: cytological studies in the tribe saxifrageae. dansk bot. arkiv 8(5): 1-52. stenstrom, m. & molau, u. 1992: reproductive ecology of saxifraga oppositifolia: phenology, mating system, and reproductive success. arct. alp. res. 24, 337-343. tollefsrud, m. m., bachmann, k., jakobsen, k.s. & broch mann, c. 1995: rapd variation in an arctic-alpine, polyploid inbreeder: saxifraga cespitosa. abstract, vi international symposium iopb, ”variation and evolution in arctic and alpine plants”, tromse, norway. ugborogho, r. e. 1973: north american cerastium arvense l. i . cytology. cytologia 38, 559-566. webb, d. a. & gomall, r. j. 1989: a manual of saxifrages and their cultivation. timber press, portland. evidence from testate amoebae for changes in some local hydrological conditions between c. 5000 bp and c. 3800 bp on edgebya (svalbard) l. beyens and d. chardez beyens, l. & chardez. d. 1987: evidence from testate amoebae for changes in some local hydrological conditions between c. 5000 bp and c. 3800 bp on edge~iya (svalbard). polar research 5 n.s., 165169. the study of a subfossil peat from the northwestern part of edgedya (svalbard) enabled a reconstruction of the changes in the testate amoebae communities from c. 5000 bp t o c. 3800 bp to be made. two stratigraphical zones are recognized. the ecological interpretation of these sequences revealed rather humid and unstable hydrological conditions at the bog surface in the oldest zone, which presumably lasted until about 45004300 bp. the communities in the upper zone indicated a more stable and drier environment. l . beyens, department of botany, ruca, groenenborgerlaan, 171, b-2020 antwerpen, belgium; d . chardez, lab. de zoologie gtwrale, facult6 des sciences agronomiques de i'etat, b-5800 gembloux, belgium; january 1987 (revised may 1987). ',j. ~ ~ l ~ r ~ n s ~ ' ' recent testate amoebae communities in the arc tic are mostly dominated by cosmopolitan, readily distributed species, and it seems probable that colonization of new areas after the last glaciation tended to be limited by the availability of suitable habitats rather than by immigration rates. the was taken at regular intervals, and numbered 1 to 24 from the top downwards. two radiocarbon datings were made by prof. w. g. mook, isotope physics laboratory, groningen (van der knaap 1986): -sample no. 1 (top): 3810 f 40 years bp (grn degree of moisture in the habitat is a parameter of prime importance, and changes in the local hydrological conditions can be detected by study ing fossil assemblages. fossil peat layers, although not so frequently encountered in the high arctic, are therefore important archives. such a fossil peat was observed during our 1984 field season on edgeeya, while working on the present distri bution and ecology of testate amoebae and diatoms. the results (in prep.) of that fieldwork permit us t o interpret the ecological significance of the community changes represented in the time span of this peat. material and methods the site is located on the northwestern side of e d g e ~ y a , svalbard (fig. l), in the valley rosen bergdalen, approximately 1300 m from the coast. the peat layer was found in the exposed slope of a glacial terrace, south of the river. this 2 m thick peat layer was sampled by dr. w. 0. van der 13349) i cf i knaap (utrecht), who made the fig. 1 . sketch map of svalbard (excluding bear island), showing available to us. a vertical series of 24 samples the location of rosenbergdalen on e d g e ~ y a . 166 l. beyens & d . chardez 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 2 0 21 22 23 24 20 70 7 0 2 0 30 fig 2 testate amoebae diagram from rosenbergdalcn. > > i -sample no. 24 (bottom): 4995 * 45 years bp (grn-13350) from every sample, an equal weight of air dried peat (1 g) was shaken with 100 cc distilled water, and filtered through sieves with meshes of 1 mm and 0.250mm. testate amoebae in the filtrate were counted with the reverse microscope. results are shown in fig. 2, expressed as per centages of the total number of tests at each level. we must stress that the number of tests is sometimes very low. a fact which should be borne in mind when evaluating the results. results and discussion the following taxa were found: arcella arenaria greeff, centropyxis aerophila deflandre. cen tropyxis aerophila var. sphagnicola deflandre, centropyxis syluatica (deflandre) thomas, cen tropyxis minuta deflandre. centropyxis cassis var. minima van o y e , difjlugia bryophila (penard) jung. diffiugia lucida penard, difflugia penardi (penard) hopkinson, euglypha ciliata ehrenberg, euglypha rotunda wailes, trinema lineare penard. phryganella acropodia (hert. et less.) hopkinson, phryganella acropodia var. penardi decloitre. a few taxa dominate the faunal assemblage throughout the sequence (fig. 2), particularly centropyxis aerophila, its variety sphagnicola and 1 1 i 20 70 40 40' i 0 i trinema lineare. t h e following observations on their representation (summarized in table 1) can be made: -the curve of centropyxis aerophila becomes continuous from level 9 t o 1. -centropyxis aerophila var. sphagnicola shows the same trend. except for a minimum at level 7. -trinema lineare is better represented in the lower half of t h e section. based o n the presence and representation of the various taxa, two stratigraphical zones are distinguished; t h e first zone a includes a" where no tests were found, a n d a , (level 22 to 10) with trinema lineare as t h e dominant species. t h e second, zone b , is characterized by centropyxis aerophila and its variety. this zonation is con firmed by t h e curve for jaccard similarities between samples (fig. 3a), where continuously high values of similarity only occur from level 7 upwards. t h e minimum between levels 8 and 7 table 1 . mean percentual frequencies of the main species in both zones. centr. aerophila 3 1 . 3 60.9 + var. sphagnicola trinema lineare 43.9 22.4 evidence from testate amoebae 167 table 2. ecology of some species based on recent observations on e d g e ~ y a (beyens & chardez in prep.) f: moisture content class according to jung (1936). (fiii = very wet-water drips from the sample without pressure; r v = wet-water drips on application of only slight pressure; fvii = quasi-dry-nly a few drops of water can be squeezed out; wiii = dry-no water is exuded even after high pressures are applied.) species numbers of samples in which encountered moisture content of the moss habitat centropyxis aerophila var. sphagnicola centropyxis minuta difpugia lucida difpugia bryophila difpugiu penardi difpugia penardi + diflugia lucida 0 is due t o the absence of centropyxis aerophila sphagnicola. the interpretation of these fossil assemblages is made possible through our studies of recent moss-dwelling communities in the arctic. macro botanical analyses revealed great numbers of moss-remains (van der knaap 1986). thus, we may assume that most testate amoebae were related to the moss habitat. in a previous study it was shown that trinerna lineare occupies a range from humid to moderately humid con ditions, while the centropyxis aerophila associ ation was found to live in drier conditions (beyens et al., 1986). some ecological observations related to other species made during the field seasons of 1984 and 1985 are compiled in table 2. the specific differences in ecology with regard to the moisture content of the substratum lead to the conclusion that, on the whole, more humid conditions prevailed in zone a than in zone b. more detailed analyses reveal that in a l there were also periods during which drier conditions existed, as indicated by the frequencies of cen tropyxis aerophila and centropyxis aerophila sphagnicola. hydrological conditions at the bog surface were thus rather unstable, as reflected in the lower similarity between the associations of the successive layers. the low diversity indices (fig. 3b) are also suggestive of environmentally stressful situations resulting from the alternation between more humid and drier phases. the most humid conditions probably occurred at level 13, where diflugia lucida and difflugia penardi are found together. at the present day on edgeoya they were observed together in mosses which were so wet that the water dripped from the samnle without dressure. in the diagram there m p 5 v) is sp. l8 t it) 22 23 0 25 50 in 72%; less humid to dry dry: fvii-fviii in 85%: fiii-fiv in 75%: fiii-fiv in 84%: fiii-fiv fiii, fiv, fiii-iv c 0 . e s n h fig. 3. a: the similarity (is,) between the successive communi ties, computed according to the formula of jaccard as modified by spatz (1970). b: the diversity index (h), computed accord inr! to the shannon-weiner formula. 168 l . beyens & d . chardez are no indications of a subaquatic bog surface. the main similarity and diversity are here 8.13 and 0.57, respectively. an important change in hydrological conditions happened between level 10 and level 9, i.e. from here on the bog surface seems to remain only moderately humid to dry. over long periods there were no dramatic changes, as confirmed by the higher similarity and diversity indices (mean more humid drier i' fig. 4 . the evolution of the moisture content at the bog surface. as reflected by differences in percentual frequencies between the more humid and the drier livine soecies. values of 27.86 and 1.13, respectively). we have tried t o represent these fluctuations diagrammatically, computing the differences between the sum of the percentages of the mod erate to dry living taxa and the sum of more humid ones (fig. 4). although it is a rough method, it gives what may be a reliable picture of the succession. comparison with the similarity curve shows that this index is, as expected, generally higher during periods with stable moisture con ditions at the bog surface. it is obvious that from level 9 upwards, some environmental change has induced the dry con ditions. local events such as the diminution of run-off caused by some geomorphological fea tures may be involved. o n the other hand, a more general factor such as climatic change is also plausible. this would have a direct influence on e.g. the amount of precipitation, the melting of snowfields, and the depth of the active layer. in this context, the number of tests preserved in 1 g of peat (fig. 2) is instructive. it is probable that there was some selective destruction, especially when the tests were still in the active layer. but once in the permafrost, it is unlikely that chemical or mechanical destruction occurs. in the upper part of zone b, from level 6 on, which corresponds with a depth of c. 66cm, numbers remain high. if a cooling trend is assumed from level 9 on, then the permafrost table must have risen, and shells must have been incorporated more quickly into the permafrost. however, this is still no more than a hypothesis. in a well-developed moss tundra on edgeeya we have observed active layer depths of 25 cm. another problem is the dating of the major hydrological change. when we extrapolate between the two radiocarbon dates, we find that level 10 is situated around 4245 bp. however, such a linear peat-growth rate is unlikely, since zone b was drier than zone a. we must therefore assume that the transition between a and b is older, and probably falls into the range of 4500 4300 bp. it is worth noting that from other regions (e.g. n.w. greenland) indications of changes in the climatological conditions are known for the period 4500 bp-3500 bp (fredskild 1985), and although it is tempting to link our result to some of these, this is impossible at the present stage of our research. further testate amoebae analyses from edge@ya as well as from other parts of the .,. arctic are planned in the future. evidence from testate amoebae 169 acknowledgements. we wish to thank mrs. pooters, mrs. a. torfs, and mr. r. neefs for their technical assistance. dr. p. oosterveld (netherlands foundation for arctic biological research) provided logistic support at the kapp lee scientific station. we are also grateful to dr. w. 0. van der knaap (utrecht) for the peat samples. prof. dr. d. k. ferguson kindly corrected the english text. one of us (l.b.) received grants from the national science foundation (belgium) for the edgeeiya-expeditions. references beyens, l., chardez, d. & de landtsheer, r., with col laboration of de bock, p. & jacques, e. 1986: testate amoe bae populations from moss and lichen habitats in the arctic. polar biol. 5,165-173. fredskild. b. 1985: the holocene vegetational development of tugtuligssuaq and qeqertat, northwest greenland. meddr. grgnland, geosci. 14, 3-20. jung, w. 1936: thecamoben urspriinglicher lebender deutscher hochmoore. abh. landesmus. wesif. 7 , 1-87. knaap, w. 0. van der 1986: on the presence of reindeer (ran gifer tarandus l . ) on edgeeiya, spitsbergen in the period 3800-5000 bp. circumpolar journal 2, 3-9. spatz, g. 1970: pflanzengeselhchaften, leistungen und lebt ungspoieniial uon allgiiuer alpweiden in abhiingigkeit uon standort und bewirtschaftung. dissertation, techn. univ., munich. 160 pp. polar bears observed climbing steep slopes to graze on scurvy grass in svalbard research note polar bears observed climbing steep slopes to graze on scurvy grass in svalbard lech stempniewicz department of vertebrate ecology and zoology, faculty of biology, university of gdańsk, gdańsk, poland abstract it is well known that polar bears feed on vegetation. here, i report novel observations of polar bears grazing on polar scurvy grass (cochlearia groenlandica) at the foot of a large seabird colony on a cliff on spitsbergen, svalbard, in the summers of 2005, 2006, 2009, 2014 and 2015. why they choose such energy-costly climbing to feed on plants is not clear. one possibility is that they may be suffering from vitamin c deficiency and are searching for this particular plant, which has a high level of this vitamin. another, but not exclusive reason, is that vegetation containing scurvy grass is abundant enough to be efficiently grazed by such unspecialized plant-eaters as polar bears only on such relatively inaccessible, steep slopes below seabird colonies. most of the lowland and gently sloping tundra areas in svalbard are overgrazed by geese and reindeer, the populations of which have increased considerably as a consequence of climate amelioration. large seabird colonies are known to attract animals from different trophic levels, but this is the first description of their attractiveness to polar bears as grazing areas. keywords carnivores feeding on vegetation; ursus maritimus; diet; cochlearia groenlandica; svalbard the polar bear (ursus maritimus) is considered a specialist hunter primarily of seals (derocher et al. 2002). they have also been observed to kill small whales such as belugas (delphinapterus leucas), narwhals (monodon monoceros) and white-beaked dolphins (lagenorhynchus albirostris) when these have become trapped in sea ice (smith & sjare 1990; aars et al. 2015). however, according to modern taxonomic classification, the polar bear is a sister species to the opportunistic omnivorous brown bear (ursus arctos) (wozencraft 2005) and under some circumstances, for example when stranded on land, appear to be quite opportunistic. they will consume a wide variety of other foods, including ungulates like muskox (ovibos moschatus) and reindeer (rangifer tarandus), birds, eggs, rodents and crustaceans, and other polar bears (lunn & stirling 1985; stempniewicz 1993, 2006; donaldson et al. 1995; derocher et al. 2002; derocher 2012; stempniewicz et al. 2014; prop et al. 2015). however, none of these animals make up a significant part of their diet (russell 1975; derocher et al. 2000; brook & richardson 2002). it is thought that polar bears cannot derive sufficient caloric intake from terrestrial food (ramsay & hobson 1991; rode et al. 2015). however, gormezano and rockwell (2015) have calculated that the probability of land-locked polar bears surviving climate change depends largely on the duration of the ice-free season and local availability of novel high-energy terrestrial foods (geese, eggs, caribou). if polar bears can adapt their foraging behaviour to effectively exploit these resources, predictions for starvation-related mortality may be overestimated. both marine and terrestrial plants are part of the polar bear diet. russell (1975) suggests that they may seek plants even when animal food is plentiful. the most common plant food is kelp (fucus spp. and laminaria spp.), eaten presumably as a source of vitamins and minerals. different grass species, including lyme grass (leymus arenarius), are the most common terrestrial plants taken by bears. depending on the locality, polar bears consume different kinds of carbohydrate-rich berries (empetrum nigrum, vaccinium spp. and juniperus communis). they take the leaves and stems of shrubs and herbs in trace amounts only. mosses and mushrooms are occasionally eaten in considerable quantities, possibly as a source of vitamins and minerals (russell 1975). though common throughout the european and american arctic, polar scurvy grass (cochlearia groenlandica) has not yet been mentioned in the available literature as a component of the polar bear’s diet (derocher 2012; gormezano & rockwell 2013a, b). polar scurvy grass, which belongs to the family brassicaceae (cruciferae), is a common plant growing along the entire svalbard coast, and is characterized contact lech stempniewicz biols@univ.gda.pl department of vertebrate ecology and zoology, faculty of biology, university of gdańsk, wita stwosza 59, pl-80-308 gdańsk, poland polar research, 2017 vol. 36, 1326453 https://doi.org/10.1080/17518369.2017.1326453 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1326453&domain=pdf by its high vitamin c content. inuit people, experienced polar explorers and trappers knew of the remedial antiscorbutic features of the plant and used it accordingly (aiken et al. 2007). owing to its tolerance to high nutrient levels in the soil, scurvy grass is most abundant in the vicinity of well fertilized seabird colonies (eurola & hakala 1977; ellis et al. 2011; zmudczynska-skarbek et al. 2013; wojciechowska et al. 2015). it is well known that large seabird colonies in the arctic, surrounded by highly productive ornithogenic tundra, attract various species of herbivores – such as geese and reindeer – scavengers and predators – e.g., glaucous gulls (larus hyperboreus), arctic foxes (vulpes lagopus) and polar bears – searching for easily available plant and animal food (stempniewicz 1990; jakubas et al. 2008; zwolicki et al. 2013, 2016). however, the attractiveness of such areas for plant grazing by polar bears has not been described. observations during fieldwork in july and august 2005, 2006, 2009, 2014 and 2015, one to three polar bears were observed each summer grazing on polar scurvy grass on the talus slope below the large kittiwake (rissa tridactyla) and brünnich’s guillemot (uria lomvia) colony at gnåloden (77°01′n 15°52′e), hornsund, south-west spitsbergen. the remains of birds (eggs, chicks, dead/injured adults) are readily discovered at the foot of the cliff colony, but the bears climbed high up on the steep talus slope (inclination 45–50°) and were focusing on the wide zone of lush vegetation several metres below the foot of the colony (fig. 1). they had apparently come there in order to graze on scurvy grass where it was most abundant, ca. 10–30 m below the foot of the colony. there, scurvy grass reaches its largest individual size and highest density and biomass, all of which then decline towards the shore (zmudczynska-skarbek et al. 2013). the calorific value of the plants occurring there was enhanced as the majority of them were flowering and producing seeds (wojciechowska et al. 2015). the grazing bears were moving along the horizontal strip of the dense, sturdy plants (fig. 1). having traversed the slope, the bears left large patches of grazed scurvy grass plants behind. all 17 fresh polar bear faeces sampled in the area contained exclusively scurvy grass remnants. discussion the large-scale shrinking of sea ice reported in recent decades in the arctic (kwok et al. 2009; onarheim et al. 2014) has reduced the area of natural polar bear hunting habitat and has forced some bears to search for terrestrial food (ramsay & hobson 1991; prop et al. 2015). the consequence of this is an evident long-term decline in their body condition (stirling & derocher 2012; obbard et al. 2016; tartu et al. 2016). most mammals can produce vitamin c endogenously based on the food they ingest. in the case of predators, the fresh meat and fat of their prey are natural sources. for polar bears, blubber, skin and, especially, liver, where ascorbic acid is synthesized, provided by seals, their staple prey, are the most important natural figure 1. polar bear grazing on polar scurvy grass below the seabird colony in hornsund; another individual defecating below the bird cliff after feeding on scurvy grass. 2 l. stempniewicz sources of the vitamin, comparative to those found in blueberries (vaccinium uliginosum) (fediuk et al. 2002). however, the rate of vitamin c synthesis in liver tissue is lower in some carnivores, e.g., dogs, compared to other animals (chatterjee et al. 1975) and consequently, vitamin c has been given as a supplement even to healthy well-fed dogs (hesta et al. 2008). we may speculate that polar bears remaining on land, where they have very limited access – if any – to seals and have been starving/ fasting for a long time, may suffer from a deficiency of vitamin c. polar scurvy grass occurs widely in svalbard, but apart from the areas near the colony of piscivorous birds, the plants are usually sparsely distributed and short, no taller than 3 cm (wojciechowska et al. 2015). moreover, the climate-induced increase in the populations of geese and reindeer in svalbard observed in recent decades has led to overgrazing of the lowland tundra vegetation (olofsson 2006; aubry et al. 2013). as a result most plants easily grazed by herbivores barely protrude above the ground, which makes them inaccessible to polar bears. it remains undetermined whether polar bears select scurvy grass because of its high vitamin c content or are searching for sites with any soft tissue plant abundant enough for grazing and the scurvy grass growing at the foot of the seabird colonies best meets this condition. disclosure statement no potential conflict of interest was reported by the author. funding the study was supported by funds from poland through the polish ministry of science and higher education (ipy/ 25/2007) and from norway through the norwegian financial mechanism (alkekonge, pnrf-234-ai-1/07 and glaere, pol-nor/199377/91/2014). references aars j., andersen m., brenière a. & blanc s. 2015. whitebeaked dolphins trapped in the ice and eaten by polar bears. polar research 34, article no. 26612, doi: 10.3402/ polar.v34.26612 aiken s.g., dallwitz m.j., consaul l.l., mcjannet c.l., boles r.l., argus g.w., gillett j.m., scott p.j., elven r., leblanc m.c., gillespie l.j., brysting a.k., solstad h. & harris j.g. 2007. flora of the canadian arctic archipelago: descriptions, illustrations, identification, and information retrieval. cochlearia groenlandica l. ottawa: nrc research press, national research council of canada. accessed on the internet at http:// nature.ca/aaflora/data on 10 december 2016. aubry l.m., rockwell r.f., cooch e.g., brook r.w., mulder c.p. & koons d.n. 2013. climate change, phenology, and habitat degradation: drivers of gosling body condition and juvenile survival in lesser snow geese. global change biology 19, 149–160. brook r.k. & richardson e.s. 2002. observations of polar bear predatory behaviour toward caribou. arctic 55, 193–196. chatterjee i.b., majumber a.k., nandi b.k., & subramanian n. 1975. synthesis and some major functions of vitamin c in animals. annals of the new york academy of sciences 258, 24–47. derocher a., wiig ø. & bangjord g. 2000. predation of svalbard reindeer by polar bears. polar biology 23, 675–678. derocher a.e. 2012. polar bears. a complete guide to their biology and behaviour. baltimore, md: johns hopkins university press. derocher a.e., wiig ø. & andersen m. 2002. diet composition of polar bears in svalbard and the western barents sea. polar biology 25, 448–452. donaldson g.m., chapdelaine g. & andrews j.d. 1995. predation of thick-billed murres, uria lomvia, at two breeding colonies by polar bears, ursus maritimus, and walruses, odobenus rosmarus. canadian field-naturalist 109, 112–114. ellis j., bellingham p., cameron d., croll d., kolb g., kueffer c., mittelhauser g.h., schmidt s., vidal e. & wait d.a. 2011. effects of seabirds on plant communities. in mulder c. et al. (eds.): seabird islands. ecology, invasion and restoration. pp. 135–176. new york: oxford university press. eurola s. & hakala a. 1977. the bird cliff vegetation of svalbard. aquilo seria botanica 15, l–18. fediuk k., hidiroglou n., madére r. & kuhnlein h.v. 2002. vitamin c in inuit traditional food and women’s diets. journal of food composition and analysis 15, 221–235. gormezano l.j. & rockwell r.f. 2013a. what to eat now? shifts in terrestrial diet in western hudson bay. ecology and evolution 3, 3509–3523. gormezano l.j. & rockwell r.f. 2013b. dietary composition and spatial patterns of polar bear foraging on land in western hudson bay. bmc ecology 13, article no. 51, doi: 10.1186/1472-6785-13-51 gormezano l.j. & rockwell r.f. 2015. the energetic value of land-based foods in western hudson bay and their potential to alleviate energy deficits of starving adult male polar bears. plos one 10, article no. e0128520, doi: 10.1371/journal.pone.0128520 hesta m., ottermans c., krammer-lucas s., zentek j., helweg p., buyse j., & janssens g.p.s. 2008. the effect of vitamin c supplementation in healthy dogs on antioxidative capacity and immune parameters. journal of animal physiology and animal nutrition 93, 26–34. jakubas d., zmudczyńska k., wojczulanis-jakubas k. & stempniewicz l. 2008. faeces deposition and numbers of vertebrate herbivores in the vicinity of planktivorous and piscivorous seabird colonies in hornsund, spitsbergen. polish polar research 29, 45–58. kwok r., cunningham g.f., wensnahan m., rigor i., zwally h.j. & yi d. 2009. thinning and volume loss of the arctic ocean sea ice cover: 2003–2008. journal geophysical research—oceans 114, article no. c07005, doi: 10.1029/2009jc005312 lunn n.j. & stirling i. 1985. the significance of supplemental food to polar bears during the ice-free period of hudson bay. canadian journal of zoology 63, 2291– 2297. obbard m.e., cattet m.r.l., howe e.j., middel k.r., newton e.j., kolenosky g.b., abraham k.f. & polar research 3 https://doi.org/10.3402/polar.v34.26612 https://doi.org/10.3402/polar.v34.26612 http://nature.ca/aaflora/data http://nature.ca/aaflora/data https://doi.org/10.1186/1472-6785-13-51 https://doi.org/10.1371/journal.pone.0128520 https://doi.org/10.1029/2009jc005312 greenwood c.j. 2016. trends in body condition in polar bears (ursus maritimus) from the southern hudson bay subpopulation in relation to changes in sea ice. arctic science 2, 15–32. olofsson j. 2006. shortand long-term effects of changes in reindeer grazing pressure on tundra heath vegetation. journal of ecology 94, 431–440. onarheim i.h., smedsrud l.h., ingvaldsen r.b. & nilsen f. 2014. loss of sea ice during winter north of svalbard. tellus series a 66, article no. 23933, doi: 10.3402/tellusa. v66.23933 prop j., aars j., bardsen b.-j., hanssen s.a., bech c., bourgeon s., de fouw j., gabrielsen g.w., lang j., noreen e., oudman t., sittler b., stempniewicz l., tombre i., wolters e. & moe b. 2015. climate change and the increasing impact of polar bears on bird populations. frontiers in ecology and evolution 3, article no. 33, doi: 10.3389/fevo.2015.00033 ramsay m.a. & hobson k.a. 1991. polar bears make little use of terrestrial food webs: evidence from stable-carbon isotope analysis. oecologia 86, 598–600. rode k.d., robbins c.t., nelson l. & amstrup s.c. 2015. can polar bears use terrestrial foods to offset lost icebased hunting opportunities? frontiers in ecology and the environment 13, 138–145. russell r.h. 1975. the food habits of polar bears of james bay and southwest hudson bay in summer and autumn. arctic 28, 117–129. smith t.g. & sjare b. 1990. predation of belugas and narwhals by polar bears in nearshore areas of the canadian high arctic. arctic 43, 99–102. stempniewicz l. 1990. biomass of dovekie excreta in the vicinity of a breeding colony. colonial waterbirds 13, 62–66. stempniewicz l. 1993. the polar bear ursus maritimus feeding in a seabird colony in franz josef land. polar research 12, 33–36. stempniewicz l. 2006. polar bear predatory behaviour toward molting barnacle geese and nesting glaucous gulls on spitsbergen. arctic 59, 247–251. stempniewicz l., kidawa d., barcikowski m. & iliszko l. 2014. unusual hunting and feeding behaviour of polar bears on spitsbergen. polar record 50, 216–219. stirling i. & derocher a.e. 2012. effects of climate warming on polar bears: a review of the evidence. global change biology 18, 2694–2706. tartu s., bourgeon s., aars j., andersen m., ehrich d., thiemann g.w., welker j.m. & routti h. 2016. geographical area and life history traits influence diet in an arctic marine predator. plos one 11, e0155980, doi: 10.1371/journal.pone.0155980 wojciechowska a., zwolicki a., barcikowski a. & stempniewicz l. 2015. the structure of cochlearia groenlandica population along the bird colony influence gradient (hornsund, spitsbergen). polar biology 38, 1919–1930. wozencraft w.c. 2005. order carnivora. in d.e. wilson & d.m. reeder (eds.): mammal species of the world: a taxonomic and geographic reference. 3rd edn. pp. 532– 628. baltimore: johns hopkins university press. zmudczynska-skarbek k., barcikowski m., zwolicki a., iliszko l. & stempniewicz l. 2013. variability of polar scurvygrass cochlearia groenlandica individual traits along a seabird influenced gradient across spitsbergen tundra. polar biology 36, 1659–1669. zwolicki a., zmudczyńska-skarbek k., iliszko l. & stempniewicz l. 2013. guano deposition and nutrient enrichment in the vicinity of planktivorous and piscivorous seabird colonies in spitsbergen. polar biology 36, 363–372. zwolicki a., zmudczyńska-skarbek k., richard p. & stempniewicz l. 2016. importance of marine-derived nutrients supplied by planktivorous seabirds to high arctic tundra plant communities. plos one 11, e0154950, doi: 10.1371/journal.pone.0154950 4 l. stempniewicz https://doi.org/10.3402/tellusa.v66.23933 https://doi.org/10.3402/tellusa.v66.23933 https://doi.org/10.3389/fevo.2015.00033 https://doi.org/10.1371/journal.pone.0155980 https://doi.org/10.1371/journal.pone.0154950 abstract observations discussion disclosure statement funding references description of plant communities on half moon island, antarctica research article description of plant communities on half moon island, antarctica daniela schmitz a, jair putzkeb, margéli pereira de albuquerque b, adriano luis schünemann b, frederico costa beber vieirab, filipe de carvalho victoria b & antônio batista pereira b adepartamento de biologia vegetal, laboratório de ecologia evolutiva de plantas, universidade federal de viçosa, viçosa, brazil; bnúcleo de estudos da vegetação antártica, universidade federal do pampa, são gabriel, brazil abstract during february–march of the austral summers of 2013/14 and 2014/2015, fieldwork was performed on half moon island, south shetland archipelago, antarctica, to evaluate the distribution and abundance of mosses and lichens, as well as to describe and map the plant communities there. the quadrat (20 × 20 cm) sampling method was employed in a phytosociological study that aimed to describe these communities. the area was mapped using an astech promark ii® dgps, yielding sub-metric precision after post-processing with software. the number of species totalled 38 bryophytes, 59 lichens, only one flowering plant (deschampsia antarctica desv.), and two macroscopic terrestrial algae. five types of plant communities were identified on the island, as follows: (1) fruticose lichen and moss cushion, (2) moss carpet, (3) muscicolous lichen, (4) crustose lichen and (5) moss turf. keywords phytosociology; antarctic plant distribution; bryophytes; lichens; plant community mapping abbreviation ies: index of ecological significance introduction half moon island (62°35′s and 59°55′w) is one of the smallest islands in the south shetland archipelago, antarctica. this island is visited daily by tourists, who are mainly attracted by its penguin colonies and by the fact that, apart from the giant petrel, all birds that reproduce in the antarctic can be found on this island (olrog 1958; favero & silva 1991; esponda et al. 2000). teniente camara base (argentina) is located on this island. the antarctic flora is composed mainly of bryophyte and lichen species adapted to harsh conditions and low temperatures, with 111 moss species described and 360 lichen species accepted by taxonomists occurring in the region, although recent studies indicate that the number of lichen species could actually be as high as 500 species. regarding angiosperms, only two species of native flowering plants have been described from antarctica, which are deschampsia antarctica (desv.) and colobanthus quitensis (kunth) bartl. (pereira & putzke 1994; øvstedal & lewis-smith 2001, 2004; putzke & pereira 2001; chwedorzewska et al. 2008; ochyra et al. 2008; øvstedal & schaefer 2013). the vegetation of half moon island was first reported by lindsay (1971) after a short-term excursion (6 h) in the area, but no reference has been made to any specific species. there are colonies of almost all representative antarctic birds breeding on the island, in addition to colonies of seals resting in the area, which could suggest an association between the presence of these animals with the occurrence of plants there. birds were counted on this island in some previous studies (olrog 1958; favero & silva 1991; esponda et al. 2000). according to esponda et al. (2000), there were 10 breeding species on this island in the antarctic summer of 1995/96: chinstrap penguins (pygoscelis antarctica; 3342 pairs), cape petrels (daption capense; eight), wilson’s storm petrels (oceanites oceanicus; 377), black-bellied storm petrels (fregetta tropica; seven), antarctic cormorants (phalacrocorax atriceps bransfieldensis; 29), subantarctic skuas (catharacta antarctica; three), south polar skuas (c. maccormicki; 103), kelp gulls (larus dominicanus; 39), antarctic terns (sterna vittata; 125) and greater sheathbills (chionis alba; 11). tourism is on the rise in antarctica, and half moon island is one of the areas most visited by tourists. according to the association of antarctic tourism operators, tourism on this island has increased nearly eightfold from 1999 to 2014 (bender et al. 2016). this has likely had an impact on the vegetation, which is a drawback for a plant community study. however, it also provides an opportunity to monitor environmental impacts and diminish future damage from anthropic activities (esponda et al. 2000). this study aimed to describe and map the distribution of plant communities on half moon island in order to contribute to efforts to monitor the impact on plant communities of touristic activities there in the future. contact frederico costa beber vieira filipevictoria@unipampa.edu.br núcleo de estudos da vegetação antártica, universidade federal do pampa, avenida antônio trilha, 1847, são gabriel, rs 97300-000, brazil supplementary data for this article can be accessed here polar research 2018, vol. 37, 1523663 https://doi.org/10.1080/17518369.2018.1523663 © 2018 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0002-3162-2430 http://orcid.org/0000-0002-8945-5030 http://orcid.org/0000-0001-7227-7074 http://orcid.org/0000-0002-8580-1813 http://orcid.org/0000-0003-0368-4594 https://doi.org/10.1080/17518369.2018.1523663 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2018.1523663&domain=pdf materials and methods half moon island is located in the south shetland archipelago, on the west side of the antarctic peninsula. it was visited during the 32nd brazilian antarctic operation, carried out in two fieldwork seasons, both in february–march of the austral summers of 2013/14 and 2014/15 . the operation used the facilities of argentina’s camara base, which was established in 1952/53, and laboratories and equipment were installed in the proximity of la morenita hill. shaped like a crescent moon, the island is located between latitudes of 62°34′50.57′′s and 62°35′54.04′′s and longitudes of 59°53′24.44′′w and 59°56′04.16′′w. its east– west and north–south dimensions are both approximately 2 km. with a total area of 152 ha, it is one of the smallest islands of the archipelago. there are three main hills on the island, among which gabriel hill is the highest point on the island, reaching 101 m a.s.l. penguin rockeries are concentrated on baliza point and are frequently visited by tourists during the summer. the study of vegetal communities on the island started with a survey to locate the vegetated areas, and the collection and identification of the plant species occurring in the area. species not identified in the field were sampled and identified later in the laboratory at camara base. species identification was performed according to guides by ochyra (1998), ochyra et al. (2008) and putzke & pereira (2001) for mosses, ochyra et al. (2008) for liverworts, and redon (1985), øvstedal & lewis-smith (2001) and olech (2004) for lichens, using the usual procedures for each group. a phytosociological survey was carried out using the methods of braun-blanquet (1964), adapted to the antarctic situation (victoria & pereira 2007). south– north lines were placed over each plant community formation, 5 m apart, with the total number of lines placed depending on the size of the vegetation formation, and sampling was maintained until no new species was found in five consecutive samples. along each line, within each 5 × 5 m plot, the abundance and coverage of each plant species was counted by using a 20 × 20 cm quadrat subdivided with a grid into 100 sub-quadrats 2 cm2 in size. a total of 358 quadrats were sampled across the island, including all the observed patches of vegetation. samples of vegetation were taken for subsequent identification if needed. the phytosociological data obtained were then used in the calculation of the ies. the ies combines the parameters of abundance (coverage and frequency, represented as c and f, respectively), as follow: ies = f(1 + c) (lara & mazimpaka 1998; marques et al. 2005; victoria & pereira 2007). the shannonwiener’s diversity index (pitkanen 1998), pielou’s evenness index (peet 1974) were used in order to describe the plant species diversity in each community formation (ludwig & reynolds 1988). the vegetal communities were mapped using an ashtech promark ii® dgps (ashtech oem), with data processed with the astech solutions® software. vegetation spots on the maps produced were then circled and subsequently classified according to the ies. the samples were dried at 40 °c (±5 °c) in a kiln in the field, and deposited at the bruno edgar irgang herbarium in the universidade federal do pampa in southern brazil. results the phytosociological analysis used data from 358 20 × 20 cm quadrats sampled in the field. the plants found included 37 bryophyte species (35 mosses and two liverworts), representing 33% of the bryophyte species described for antarctica, and 59 lichen species that comprise 15% of those described for the antarctic (supplementary table s1). only one flowering plant (deschampsia antarctica) and the macroscopic terrestrial algae prasiola crispa (lightfoot) kützing and prasiola calophylla (carmichael ex greville) kützing were found on the island. the most species-rich family of mosses on the island was bryaceae, followed by pottiaceae, while the most speciose lichen families were physciaceae and teloschistaceae. these results demonstrate that, in spite of its small size, half moon island has a great diversity of plant species compared to the amount of species existing around the antarctic continent (pereira & putzke 1994; victoria et al. 2009; victoria et al. 2013). from the data obtained by phytosociological sampling of all the vegetation on half moon island, the mosses sanionia uncinata (hedw.) loeske and sanionia georgico-uncinata (müll. hal.) ochyra & hedenäs, combined herein as sanionia spp., were the most frequently found species, followed by the lichen usnea aurantiaco-atra (jacq.) bory (table 1). according to this phytosociological study on the vegetation of half moon island, five types of plant communities were identified (table 2, fig. 1) covering approximately 19.17 ha of the island’s surface, which represents 12.5% of the total island area. these communities were mapped (fig. 2) and were characterized according to lindsay (1971), as presented in table 2. fruticose lichen community this community was found to consist mainly of fruticose lichens, such as usnea aurantiaco-atra and sphaerophorus globosus (huds.) vain., on slopes facing the north side of the island, as well as mosses like sanionia uncinata and polytrichastrum alpinum (hedw.) g.l. smith on the most stable surfaces of these slopes. this is the second largest community on the island. however, the difficulties in reaching its locations 2 d. schmitz et al. on slopes limited the number of phytosociological quadrat samples that could be taken to 36, at which point new species stopped appearing in the samples. thirty-seven plant species were identified (e = 0.8811, h′ = 1.3817) comprising mosses, lichens and the grass deschampsia antarctica (table 3) that appears sparsely in both of the hillsides of la morenita and xenia hills. some areas are transitional between the moss andreaea spp. and true fruticose lichen associations, and these are dominated by usnea aurantiaco-atra among the saxicolous species and sphaerophorus globosus, cladonia borealis s. stenroos, c. rangiferina (l.) weber ex f.h.wigg. and stereocaulon glabrum (müll. arg.) vain. among the muscicolous species. the confluence of these communities generates a well-defined complex, aggregating characteristic species of these communities and otherimportant ones,which are mostly muscicolous lichens growing on andreaea spp., such as psoroma hypnorum (vahl) gray, p. cinammomeum malme,parmeliasaxatilis (l.)ach.and,mostcommonly, ochrolechia frigida (sw.) lynge. one formation almost exclusively inhabited by fruticose lichens (saxicolous usnea aurantiaco-atra) is that found on a slope of high declivity that starts near the access to the beach north of xenia hill and then rises up to approximately 250 m a.s.l. from east to west. the small rock fragments in this formation are almost entirely covered by usnea aurantiaco-atra, giving it a very high ies (reaching 425.00) here, followed by crustose saxicolous lichens, which together reached an ies of 266.43. among the moss carpet species, only sanionia spp. were registered here (ies = 115.43), covering areas where a small amount of fine soil particles was found. among the cushion-forming mosses, andreaea gainii card., a. depressinervis card. and himantormia lugubris (hue) i.m. lamb were found sparsely, usually associated with other communities. moss carpet community moss carpet communities are mostly composed of the species sanionia spp. (table 4), which has the highest index of biomass in the antarctic islands (putzke & pereira 2001). this community is usually found on soft slopes or on slopes near drainage lines, forming table 1. list of the most frequently sampled representative species found in the phytosociological survey on half moon island, antarctica. species group number of quadratsa fb (%) iesc sanionia spp. moss 257 71.78 234.81 usnea aurantiaco-atra (jacq.) bory lichen 124 34.63 63.17 polytrichastrum alpinum (hedw) g.l. smith moss 114 31.84 49.63 ochrolechia frigida (sw.) lynge lichen 110 30.62 40.85 verrucaria sp. lichen 83 23.18 29.27 lecidea sciatrapha hue lichen 79 22.06 27.86 sphaerophorus globosus (huds.) vain. lichen 70 19.55 25.67 anumber of quadrats in which the species was recorded. bspecies frequency in 358 quadrats. cies of specie considering all samples. table 2. diversity analyses of the plant communities found on half moon island, antarctica. the number of species (s), specific diversity observed (h′), expected species diversity (hmax), and pielou evenness (j) are presented. community s h′ hmax j area (ha) fruticulose lichen 37 1.3817 1.5682 0.8811 5.08 moss carpet 51 1.3640 1.7075 0.7988 4.30 muscicolous lichen 35 1.3327 1.5440 0.8631 0.64 crustose lichen 39 1.4700 1.5910 0.9239 8.46 moss turf 30 1.3330 1.4771 0.9024 0.70 figure 1. diversity statistics of plant communities found in each community formation observed on half moon island, maritime antarctica. the differences in measurements means the significance of each index at the number of samples in each community formation. polar research 3 extensive carpets both on the tops of hills and on areas adjacent to the beach level. its occurrence is restricted to areas with a stable substrate. in this study, 51 species were identified from 191 quadrat samples of this community (e = 0.7988; h′ = 1.3640), making it the most species-rich community at the study site. the most extensive carpets are found along the northern beaches, at almost the level of the seashore, and also sparsely on the top of xenia hill, at the northern site of la morenita hill, and in the elevated areas between them. the carpets are formed mostly by sanionia uncinata, along with some tufts of brachythecium austrosalebrosum (müll. hal.) kindb. at least 1 m in size, and sparsely some warnstorfia fontinaliopsis (müll. hal.) ochyra. there is still competition, especially with bryum argenteum hedw., b. cf nivale müll. hal. and b. pseudotriquetrum (hedw.) schwaegr., which are found together with the carpets of sanionia uncinata or as completely isolated cushions. there are a few muscicolous lichens, but ring fungi are more frequent. in areas with small guano deposits, such as la morenita in the south and xenia and gabriel hills in the north, the carpets are small and also furrowing among small rocks. sometimes the carpets form large groups, which are frequently colonized by muscicolous lichens such as ochrolechia frigida, psoroma spp., cladonia spp., sphaerophorus globosus and stereocaulon glabrum. it is interesting to note that three different carpets are found in the northern portion of the island, almost at figure 2. distribution map of the plant communities on half moon island, antarctica. 4 d. schmitz et al. sea level, forming a 500-m long group, alongside two linear shallow lakes. the northernmost one contains only sanionia uncinata, the middle one has s. uncinata together with some cushions of bryum cf nivale, and the southernmost one has s. uncinata colonized by cystocoleus niger (huds.) har. and psoroma hypnorum with some small tufts of polytrichastrum alpinum. at the top of xenia hill, there is a carpet formed by sanionia uncinata (exclusively associated with bryum argenteum), and a small amount of muscicolous lichens associated with a water pond. no other place has this association on the island. on the southern face of xenia hill, near its top, another carpet can be found, which is composed of s. uncinata partially covered by muscicolous lichens, such as stereocaulon glabrum, sphaerophorus globosus and psoroma hypnorum, as well as ochrolechia frigida and cladonia spp. some of these muscicolous lichens are associated with andreaea, which is scarce in this association. this formation indicates that a muscicolous community probably occupies the area, and could replace the moss carpet formation in the future; however, further evaluations will be necessary to appraise this succession hypothesis. on the flat area of xenia hill there are two other types of carpets, one of which is s. uncinata that is slightly colonized, but not enough to justify its characterization as muscicolous. another carpet is found high at the top of gabriel hill, formed by s. uncinata with patches of andreaea spp. covering the rocks. this association is noteworthy because it is difficult to identify to which assemblage type it exactly belongs, but in fact there are two carpets here isolated by an andreaea association. a carpet was found ca. 20 m south of camara base, of which s. uncinata is the main component. in this area, the sanionia coverage and frequency becomes larger towards the west. there are other components here, such as andreaea spp. and polytrichastrum alpinum among the mosses, but they are less representative towards the west, and the same trend occurs with saxicolous and muscicolous lichens here. muscicolous lichen community this community represents the vast majority of the moss formations on the island. thirty-five species were identified in this formation (table 5), of which a total of 46 quadrats were evaluated (e = 0.8631, h′ = 1.3327). there is a mix of many moss species, among which s. uncinata is the most abundant. the mosses are colonized by table 3. phytosociological data for the fruticose lichen communities on half moon island, including the frequency (f), coverage (c) and ies for each species. species group f c ies usnea aurantiaco-atra (jacq.) bory lichen 100 3.25 425.00 sanionia spp. moss 61.11 0.888 115.43 sphaerophorus globosus (huds.) vain. lichen 47.22 0.666 78.70 ochrolechia frigida (sw.) lynge lichen 44.44 0.444 64.19 lecidea sciatrapha hue lichen 38.88 0.444 56.17 polytrichastrum alpinum (hedw.) g.l. smith moss 36.11 0.5 54.16 verrucaria sp. lichen 33.33 0.388 46.29 cladonia metacorallifera asahina lichen 33.33 0.361 45.37 lecidea sp. lichen 30.55 0.416 43.28 andreaea depressinervis card. moss 27.77 0.527 42.43 stereocaulon glabrum (müll. arg.) vain. lichen 22.22 0.472 32.71 rhizoplaca aspidophora (vain.) redón lichen 25 0.25 31.25 andreaea gainii card. moss 19.44 0.222 23.76 andreaea regularis muell. moss 16.66 0.222 20.37 schistidium steerii ochyra moss 13.88 0.166 16.20 dicranoweisia grimmiaceae (müll. hal.) broth. moss 13.88 0.138 15.81 microglaena antarctica i.m. lamb lichen 13.88 0.138 15.81 rhizocarpon polycarpum (hepp) th. fr. lichen 13.88 0.138 15.81 psoroma cinammomeum malme lichen 11.11 0.166 12.96 cladonia rangiferina (l.) weber ex f.h. wigg. lichen 11.11 0.138 12.65 buellia latemarginata darb. lichen 11.11 0.111 12.34 ceratodon purpureus (hedw.) brid. moss 11.11 0.111 12.34 rhizocarpon geographicum (l.) dc. lichen 11.11 0.111 12.34 cystocoleus niger (huds.) har. lichen 8.33 0.111 9.25 polytrichum piliferum hedw. moss 8.33 0.083 9.02 caloplaca athallina darb. lichen 5.55 0.055 5.86 cladonia furcata (huds.) schrad. lichen 5.55 0.055 5.86 ochrolechia parella (l.) a. massal. lichen 5.55 0.055 5.86 parmelia saxatilis (l.) ach. lichen 5.55 0.055 5.86 bartramia patens brid. moss 2.77 0.027 2.85 buellia russa (hue) darb. lichen 2.77 0.027 2.85 caloplaca cinericola (hue) darb. lichen 2.77 0.027 2.85 deschampsia antarctica desv. grass 2.77 0.027 2.85 cephallozia sp. liverworth 2.77 0.027 2.85 leptogium puberulum hue lichen 2.77 0.027 2.85 psoroma hypnorum (vahl) gray lichen 2.77 0.027 2.85 schistidium urnulaceum (müll. hal.) b.g. sino moss 2.77 0.027 2.85 polar research 5 lichens at different degrees of coverage, depending on the environmental conditions. these formations are usually found in the upper part of the hills, at sites of transitional communities like those between carpets of mosses and fruticose lichens. the pure andreaea spp. formations are generally colonized by ochrolechia frigida. the carpets are colonized by crustose, foliose and fruticulose lichens. this is the case on the third plateau on the way to xenia hill’s summit, at which a community of mosses formed by polytrichastrum alpinum, sanionia uncinata and andreaea spp. occurs. these mosses are almost completely colonized by the lichens cladonia spp., ochrolechia frigida, psoroma hypnorum, sphaerophorus globosus and stereocaulon glabrum. another muscicolous field is found near the edge of a cliff at the east point of the xenia plateau, which is basically composed of andreaea regularis muell. and sanionia uncinata almost entirely covered by lichens such as ochrolechia frigida, cladonia spp. and psoroma hypnorum. crustose lichen community this community is composed of crustose lichens that develop on gravel, generally in low-altitude and plain areas close to the beach level where there is probably a strong maritime influence (wind and salinity) and plants remain covered by snow for long periods. these sites have strong nitrophilous influences due to the nearby penguin colonies, favouring ornithocoprophilous species. taking into account the island’s entire area, this community comprises a total of 39 plant species (table 6) sampled in 67 quadrats (e = 0.9239, h′ = 1.4700). these communities include sparse appearances by representative mosses and table 4. phytosociological data for the moss carpet communities on half moon island, including the frequency (f), coverage (c) and ies for each species. species group f c ies sanionia uncinata (hedw.) loeske moss 91.09 3.350 396.35 polytrichastrum alpinum (hedw.) g.l. smith moss 31.41 0.565 49.17 usnea aurantiaco-atra (jacq.) bory lichen 25.13 0.544 38.81 lecidea sciatrapha hue lichen 27.74 0.335 37.04 ochrolechia frigida (sw.) lynge lichen 27.22 0.277 34.77 verrucaria sp. lichen 22.51 0.246 28.05 psoroma hypnorum (vahl) gray lichen 14.65 0.214 17.80 rhizocarpon polycarpum (hepp) th. fr. lichen 15.18 0.172 17.80 sphaerophorus globosus (huds.) vain. lichen 14.13 0.230 17.39 andreaea regularis muell. moss 14.13 0.146 16.20 rhizoplaca aspidophora (vain.) redón lichen 12.56 0.125 14.14 andreaea gainii card. moss 12.04 0.136 13.68 cladonia rangiferina (l.) weber ex f.h. wigg. lichen 10.47 0.120 11.73 cladonia metacorallifera asahina lichen 9.94 0.099 10.93 bryum cf nivale müll. hal. moss 8.89 0.146 9.82 rhizocarpon geographicum (l.) dc. lichen 8.37 0.083 9.07 acarospora macrocyclos vain. lichen 7.85 0.078 8.47 stereocaulon glabrum (müll. arg.) vain. lichen 7.32 0.104 8.09 usnea antarctica du rietz lichen 6.80 0.104 7.51 prasiola crispa (lightfoot) kützing chlorophyta 6.28 0.068 6.71 cystocoleus niger (huds.) har. lichen 6.28 0.062 6.67 cladonia borealis s. stenroos lichen 5.75 0.083 6.24 prasiola calophylla (carmichael ex greville) kützing clorophyta 5.75 0.078 6.21 bryum argenteum hedw. moss 5.23 0.151 6.03 hennediella heimii (hedw.) zand. moss 5.23 0.052 5.50 andreaea depressinervis card. moss 3.66 0.062 3.89 himantormia lugubris (hue) i.m. lamb lichen 3.14 0.036 3.25 rhizoplaca melanophtalma (dc.) leuckert & poelt lichen 2.61 0.026 2.68 polytrichum piliferum hedw. moss 2.09 0.031 2.16 buellia latemarginata darb. lichen 2.09 0.026 2.14 bryum pallescens schleich. ex schwägr. moss 1.57 0.015 1.59 huea austroshetlanica (zahlbr.) c.w. dodge lichen 1.57 0.015 1.59 microglaena antarctica i.m. lamb lichen 1.57 0.015 1.59 pannaria hookeri (borrer) nyl. lichen 1.57 0.015 1.59 psoroma cinnamomeum malme lichen 1.57 0.015 1.59 bartramia patens brid. moss 1.04 0.010 1.05 buellia anisomera vain. lichen 1.04 0.010 1.05 pohlia cruda (hedw.) lindb. moss 1.04 0.010 1.05 bryum pseudotriquetrum (hedw.) schwaegr. moss 0.52 0.010 0.52 buellia racovitzae c.w. dodge lichen 0.52 0.010 0.52 bacidia tuberculata darb. lichen 0.52 0.005 0.52 brachythecium austrosalebrosum (müll. hal.) kindb. moss 0.52 0.005 0.52 bryum dichotomum hedw. moss 0.52 0.005 0.52 buellia russa (hue) darb. lichen 0.52 0.005 0.52 caloplaca athallina darb. lichen 0.52 0.005 0.52 ceratodon grossiretis card. moss 0.52 0.005 0.52 haematomma eryhtromma (nyl.) zahlbr. lichen 0.52 0.005 0.52 lecanora skottsbergii darb. lichen 0.52 0.005 0.52 pohlia nutans (hedw.) lindb. moss 0.52 0.005 0.52 6 d. schmitz et al. fruticose lichens, which, in the future, could develop in other locations with favourable conditions.. the small peninsula that connects the hills at the north and middle–south of the island to the penguin rockery in the east are formed mainly of rounded rocks in deposits with plateau shapes. each plateau has a distinct level of stability. in general, they have greater firmness in the centre of the island than at sites close to the sea. apparently, erosionof the central plateaus is only affected anthropically. amphibious vehicles used in 2008/09, for example, left tracks still visible in those sectors. depending on their altitudinal range and the depressions between each other, these areas are differently affected by wind and snow deposits. the higher sites are generally free from ice accumulation, while the depressions are generally covered by snow. however, the general geological structure does not allow for the formation or retention of soil, which allows only a saxicolous community to become established on the peninsula, except for a small part at the north and between each of the two straight-line formations found. the pebbles and rocks here are generally colonized by crustose lichens. skuas use the area for nesting, generating some accumulation of finer particles, and such particulate pebbles and waste from the nests of birds allows the mosses to colonize these places, especially sanionia uncinata and polytrichastrum alpinum. an identical community is found on the east side of la morenita hill, at the plateau formed by the same kind of stones. verrucaria spp., buellia spp. and lecidea spp. are the main crustose lichens in this community. sanionia uncinata and andreaea spp. are the main mosses represented, and are sometimes colonized by the lichen ochrolechia frigida. this community is present as three characteristic groups on the island. one of them is restricted to the penguin rockeries in the south, where the amount of guano is large. the second is found at the north and centre of the island, where the guano supply is smaller and comes from skuas and cape petrels (daption capense) nesting in the area. the third is very peculiar, since it is linked to the rounded small rocks exposed near the beach with the regression of the sea. some animals (birds and pinnipeds) use these places as resting or molting points, depositing feathers and faeces on the rocks and generating an coprophilous community mainly composed of acarospora macrocyclos. on the cliffs of xenia hill, there are also some examples of this community type, stimulated by the presence of guano deposited by cape petrels at their nesting points. the main species in the areas are haematomma erythromma and xanthoria elegans (polycauliona candelaria), covering the higher parts of the cliffs. table 5. phytosociological data for the muscicolous lichen communities on half moon island, including the frequency (f), coverage (c) and ies for each species. species group f c ies sanionia uncinata (hedw.) loeske moss 82.60 2.021 249.62 usnea aurantiaco-atra (jacq.) bory lichen 65.21 1.956 192.81 ochrolechia frigida (sw.) lynge lichen 67.39 0.760 118.66 sphaerophorus globosus (huds.) vain. lichen 54.34 0.956 106.33 polytrichastrum alpinum g.l. smith moss 54.34 0.760 95.69 psoroma hypnorum (vahl) gray lichen 50 0.782 89.13 cladonia rangiferina (l.) weber ex f.h. wigg. lichen 47.82 0.608 76.93 cladonia metacorallifera asahina lichen 32.60 0.326 43.24 verrucaria sp. lichen 28.26 0.326 37.47 stereocaulon glabrum (müll. arg.) vain. lichen 26.08 0.434 37.42 andreaea regularis muell. moss 23.91 0.478 35.34 rhizocarpon polycarpum (hepp) th. fr. lichen 23.91 0.239 29.63 andreaea depressinervis card. moss 17.39 0.413 24.57 lecidea sciatrapha hue lichen 19.56 0.239 24.24 andreaea gainii card. moss 19.56 0.217 23.81 rhizoplaca aspidophora (vain.) redón lichen 13.04 0.173 15.31 cladonia borealis s. stenroos lichen 10.86 0.195 12.99 usnea antarctica du rietz lichen 10.86 0.195 12.99 physconia muscigena (ach.) poelt lichen 10.86 0.152 12.52 umbilicaria antarctica frey & i.m. lamb lichen 10.86 0.152 12.52 microglaena antarctica i.m. lamb lichen 8.69 0.086 9.45 prasiola crispa (lightfoot) kützing chlorophyta 8.69 0.086 9.45 acarospora macrocyclos vain. lichen 6.52 0.086 7.08 psoroma cinnamomeum malme lichen 6.52 0.065 6.94 rhizoplaca melanophtalma (dc.) leuckert & poelt lichen 6.52 0.065 6.94 pohlia cruda (hedw.) lindb. moss 4.34 0.086 4.72 rhizocarpon geographicum (l.) dc. lichen 4.34 0.043 4.53 schistidium antarctici card.) l.i. savicz & smirnova moss 2.17 0.065 2.31 buellia latemarginata darb. lichen 2.17 0.043 2.26 huea austroshetlandica (zahlbr.) c.w. dodge lichen 2.17 0.043 2.26 cystocoleus niger (huds.) har. lichen 2.17 0.021 2.22 hennediella heimii (hedw.) zand moss 2.17 0.021 2.22 himantormia lugubris (hue) i.m. lamb lichen 2.17 0.021 2.22 verrucaria tessellata (c.w. dodge) øvstedal lichen 2.17 0.021 2.22 pohlia nutans (hedw.) lindb. moss 2.17 0.011 2.17 polar research 7 table 6. phytosociological data for the crustose lichen communities on half moon island, including the frequency (f), coverage (c) and ies for each species. species group f c ies lecania brialmontii (vain.) zahlbr. lichen 37.31 0.985 74.06 buellia latemarginata darb. lichen 38.80 0.671 64.86 sanionia uncinata (hedw.) loeske moss 22.38 0.417 31.74 acarospora macrocyclos vain. lichen 20.89 0.283 26.82 turgidosculum complicatulum (nyl.) kohlm. & e. kohlm. lichen 19.40 0.373 26.64 haematomma eryhtromma (nyl.) zahlbr. lichen 17.91 0.373 24.59 rinodina petermannii (hue) darb. lichen 16.41 0.477 24.25 verrucaria sp. lichen 17.91 0.238 22.18 prasiola crispa (lightfoot) kützing chlorophyta 17.91 0.194 21.38 caloplaca regalis (vain.) zahlbr. lichen 14.92 0.313 19.60 xanthoria candelaria (l.) th. fr. lichen 14.92 0.238 18.48 candelaria murrayi poelt lichen 13.43 0.238 16.64 lecidea sciatrapha hue lichen 13.43 0.223 16.44 pannaria hookeri (borrer) nyl. lichen 13.43 0.194 16.03 bacidia tuberculata darb. lichen 11.94 0.238 14.79 usnea aurantiacoatra (jacq.) bory lichen 11.94 0.149 13.72 rhizoplaca aspidophora (vain.) redón lichen 11.94 0.119 13.36 parmelia saxatilis (l.) ach. lichen 8.95 0.253 11.22 xanthoria elegans (link) th. fr. lichen 7.46 0.149 8.57 buellia anisomera vain. lichen 7.46 0.134 8.46 ramalina terebrata hook. f. & taylor lichen 7.46 0.134 8.46 andreaea regularis muell. moss 7.46 0.074 8.01 hennediella antarctica (angstr.) ochyra & matteri moss 7.46 0.074 8.01 syntrichia magellanica (mont.) r.h. zander moss 7.46 0.074 8.01 mastodia tessellata (hook. f. & harv.) hook. f. & harv. lichen 5.97 0.104 6.59 rhizocarpon geographicum (l.) dc. lichen 5.97 0.059 6.32 rhizocarpon polycarpum (hepp) th. fr. lichen 5.97 0.059 6.32 polytrichastrum alpinum g.l. smith moss 4.47 0.059 4.74 psoroma cinnamomeum malme lichen 4.47 0.044 4.67 usnea antarctica du rietz lichen 4.47 0.044 4.67 microglaena antarctica i.m. lamb lichen 2.98 0.044 3.11 andreaea gainii card. moss 2.98 0.029 3.07 caloplaca cinericola (hue) darb. lichen 2.98 0.029 3.07 ochrolechia frigida (sw.) lynge lichen 2.98 0.029 3.07 umbilicaria decussata (vill.) zahlbr. lichen 2.98 0.029 3.07 physconia muscigena (ach.) poelt lichen 1.49 0.014 1.51 rhizoplaca melanophtalma (dc.) leuckert & poelt lichen 1.49 0.014 1.51 usnea acromelana stirt. lichen 1.49 0.014 1.51 verrucaria tessellata (c.w. dodge) øvstedal lichen 1.49 0.014 1.51 bartramia patens brid. moss 0.14 0.007 0.15 table 7. phytosociological data for the moss turf communities on half moon island, including the frequency (f), coverage (c) and ies for each species. species group f c ies polytrichastrum alpinum g.l. smith moss 72.22 2.055 220.67 sanionia uncinata (hedw.) loeske moss 50 1.166 108.33 polytrichum piliferum hedw. moss 38.88 1.166 84.25 ochrolechia frigida (sw.) lynge lichen 50 0.666 83.33 hennediella heimii (hedw.) zand. moss 38.88 0.888 73.45 rhizoplaca aspidophora (vain.) redón lichen 38.88 0.388 54.01 cladonia metacorallifera asahina lichen 33.33 0.333 44.44 verrucaria sp. lichen 27.77 0.277 35.49 bryum argenteum hedw. moss 22.22 0.388 30.86 cladonia rangiferina (l.) weber ex f.h. wigg. lichen 22.22 0.333 29.62 lecidea sciatrapha hue lichen 22.22 0.222 27.16 pohlia cruda (hedw.) lindb. moss 22.22 0.222 27.16 ceratodon purpureus (hedw.) brid. moss 22.22 0.166 25.92 cystocoleus niger (huds.) har. lichen 16.66 0.222 20.37 andreaea regularis muell. moss 16.66 0.166 19.44 psoroma cinnamomeum malme lichen 16.66 0.166 19.44 usnea aurantiacoatra (jacq.) bory lichen 11.11 0.111 12.34 andreaea depressinervis card. moss 5.55 0.277 7.09 acarospora macrocyclos vain. lichen 5.55 0.055 5.86 andreaea depressinervis card. moss 5.55 0.055 5.86 bartramia patens brid. moss 5.55 0.055 5.86 buellia anisomera vain. lichen 5.55 0.055 5.86 buellia latemarginata darb. lichen 5.55 0.055 5.86 chorisodontium acyphyllum (hook. f. & wills.) broth. moss 5.55 0.055 5.86 prasiola crispa (lightfoot) kützing chlorophyta 5.55 0.055 5.86 psoroma hypnorum (vahl) gray lichen 5.55 0.055 5.86 rhizocarpon geographicum (l.) dc. lichen 5.55 0.055 5.86 rhizocarpon polycarpum (hepp) th. fr. lichen 5.55 0.055 5.86 rhizoplaca melanophtalma (dc.) leuckert & poelt lichen 5.55 0.055 5.86 sphaerophorus globosus (huds.) vain. lichen 5.55 0.055 5.86 8 d. schmitz et al. significant ornithocoprophilous communities are found in seven areas of the island. one is located at the extreme north of the island, on a shallow cliff near the seashore that is almost completely covered by nacella concina shells in some places. the area is covered mainly by foliose/fruticose lichens such as rinodina pettermanii and haematoma erythromma, and also by crustose ones, for example buellia spp. this place was the only one on the island where we found usnea acromelana. at two sites near camara base two giant rock fragments sometimes used by kelp gulls and skuas are covered by nitrophilous communities. other hills used by gulls are situated inside the penguin colonies and, therefore, are influenced by them. the two isolated rocks are mainly covered by crustose lichens, such as acarospora macrocyclus, bacidia sp. and rhizoplaca aspidophora. moss turf community eighteen quadrats were sampled and 30 plant species were identified in this formation (e = 0.9024, h′ = 1.3330), which includes species of mosses, lichens and algae. this community is found at four sites of the island, three of which are located at higher altitudes on the tops of la morenita, gabriel and xenia hills. the other formation is at the entrance of the penguin colony at baliza point, located in a transition area composed of pebbles, ornithocoprophilous plant communities and sparse carpets of s. uncinata. there is a constant presence of fur seals at this site. the moss species with high ecological significance in this community were pohlia sp., polytrichastrum alpinum and s. uncinata (table 7). crustose lichens have also been identified in association with the moss species, totalling six distinct species. discussion estimating of the extent and coverage of plant communities is important to assess their ecological relationships with different attributes of the physical environment, such as soil, rocks and the landscape, in greater detail (simas et al. 2008). our results indicated that sanionia uncinata has the highest ies value on half moon island (234.81), followed by usnea aurantiacoatra (63.17) and polytrichastrum alpinum (49.63). on half moon island, the grass deschampsia antarctica had an ies of only 0.28 because its frequency was very low (0.28%), which was probably due to the small size of seabird colonies, as the association of this grass species with ornithogenic soils has been observed in other areas of maritime antarctica (emslie et al. 2014). in the vicinity of arctowski station (poland) in admiralty bay, king george island, victoria et al. (2009) and pinto et al. (2013) found that the maximum ies was observed for deschampsia antarctica (245 and 358, respectively), followed by sanionia uncinata (215 and 269, respectively) and polytrichastrum alpinum (153 and 81, respectively). in this study, we found that the area with grass is not generally used by bird colonies, being used mostly by a few skuas as a nesting point. in two areas with grass on half moon island, esponda et al. (2000) counted only five and two skua nesting pairs, respectively. the opposite occurred at arctowski, as the areas colonized by d. antarctica there have large nutrient input rates due to the presence of penguin colonies. the occurrence of antarctic hair-grass is important to landscape changes since the presence of the grass in plant communities generates changes in several factors in the antarctic soil. the grasses increase the carbon input to the soil, which modifies exudate input and rhizosphere microbial diversity (teixeira 2010; teixeira et al. 2013), as well as soil genesis. the adaptive success of this plant in antarctica is related to its efficient nitrogen acquisition from guano sources (hill et al. 2011). analysing the diversity indices presented in table 2 and fig. 3, it can be observed that the crustose lichen community is the most diverse on half moon island as indicated by the highest shannon diversity index (h′) and even greater evenness (j); despite it not being the most species-rich it is a more homogeneous community in which no species stands out as being dominant over all others. the moss carpet community, in turn, has the highest species richness (51), although it does not have the greatest diversity and even has the lowest evenness. this is due to the fact that s. uncinata stands out as the dominant species in this community. a previous study conducted at hennequin point on king george island in the austral summer of 2004/05 (victoria et al. 2013) showed some similar communities to those found herein on half moon island, but with different indices. the moss carpet community of hennequin point was also the most species-rich one there, but the number of species was lower (28) and it was also the most homogeneous community in that study. fruticose and crustose lichens were also found; however, these were classified as being within the same community, featuring only 28 species. the number of species of both fruticose and crustose lichens at hennequin was relatively lower than that observed on half moon island (table 2), where fruticose and crustose lichens are not found in the same communities. the fruticose lichen community on half moon island is similar to that reported by lindsay (1971), but with the andreaea moss cushion presence only in isolated spots, forming associations similar to those described by that author. accordingly, there is only one association (andreaea–usnea) in this community, and five associations. the associations found on half moon island in this community are usnea– lecidea–andreaea and andreaea–ochrolechia frigida. polar research 9 the other three associations with himantormia lugubris described by lindsay (1971) in the south shetlands were not found in this study; although some small patches of this species were observed, very sparsely distributed, they were not abundant enough to be described as an association. the exposure to high salinity is probably hampering their growth, since the island is too small to protect them from maritime influences. the formations of the moss carpet community, in which s. uncinata appeared most often, were found near drainage lines or sites under the influence of water originating from melting glaciers or lakes, as observed in admiralty bay, king george island (victoria et al. 2009; victoria et al. 2013). spots in which several species have developed in association with s. uncinata were also found. therefore, the same conditions that favour s. uncinata appear to promote adequate conditions for other species of both mosses and muscicolous lichens in these places, even in the absence of glaciers in the area studied in this work. the crustose lichen community has the greatest area of vegetation cover on the island and, in addition, is the most diverse. generally, this community is located in areas where the island birds and penguin colonies are concentrated. important conditions for some species are developed there. the direct relationship between the vegetation and the presence of nests is linked to the fact that birds provide the majority of nutrients for the initial development of plants, since the emergence of plant communities is subsequent to the establishment of nests (allen et al. 1967; leishman & wilde 2001; smykla et al. 2007). in the study by lindsay (1971), the lichen community was composed mainly of crustose lichens, although fruticose lichens could attain appreciable cover and occur on rock surfaces, particularly those subjected to wind and salt spray. at the location of this study, a high coverage by the crustose lichen verrucaria spp. can be observed, which is specifically associated with fresh or salt water (olech 2004) and exposure to wind. at hennequin point, king george island, victoria et al. (2013) found that there was a community sociation with fruticulose lichens, where they described usnea aurantiaco-atra, mastodea tesselata (hook. f. & harv.) hook. f. & harv., and lecania brialmontii (vain.) zahlbr. as the most common species. the last two, which are usually associated with colonies of birds and occur along with other ornitocoprophilous species, were not found at comparable locations on half moon island. the formation located on the top of la morenita hill resembles the sociation of polytrichastrum alpinum–polytrichum piliferum hedw. described by lindsay (1971), in which these two mosses did not form extensive turfs but occurred in small colonies that formed low piles and irregular loafs. the flat top of the hill allows the development of mosses such as s. uncinata and representatives of the family polytrichaceaea. there are other mosses on the hill formation, such as bryum argenteum and ceratodon sp., which develop among the same conditions as those preferred by the species referred to above. fruticose and crustose lichen assemblages are also developed on the rocks nearby. verrucaria species (except v. tessalata) were found in all communities in most of the sites studied on half moon island, except at the top of la morenita and xenia hills and on the slope and beach on the north side of xenia hill, i.e., areas that are probably protected from the east–west winds acting on the island. the only plant community in which verrucaria spp. were not present is that predominated by fruticose lichens, which occurs mainly on the north slope of xenia hill. according to olech (2004), verrucaria species spp. were found on rocks in the spray zone above high-tide level. this indicates that the area is constantly sprayed by marine salt, especially because it is a very small island, which explains the frequent presence of these halophilous species. colobanthus quitensis (caryophyllaceae) was not found on half moon island. this species and the grass deschampsia antarctica are the only native angiosperms found in the south shetlands islands and the maritime antarctic, reaching as far south as 68°42′s along the antarctic peninsula (moore 1970; edwards & lewis-smith 1988; putzke & pereira 2001; olech 2004; parnikoza et al. 2007). colobanthus quitensis is abundant in lower coastal regions, where it forms dense communities and occupies large areas associated with d. antarctica in all the south shetland islands. vera (2011) reported the occurrence of c. quitensis at livingston island (located south-east of half moon island) and proposed that its distribution there is related to the island’s geomorphology, suggesting that it only grows in more interior areas and at higher altitudes, where the types of other vegetation that can persist become more restricted. its dispersion is favoured by skuas for nesting, but can also occur with strong winds. these environmental factors are also found on half moon island: it is a small island, with different altitudinal ranges, strong winds, and the presence of nesting skuas. however, no c. quitensis was found in our survey, suggesting that the soil condition, the size of bird colonies or the maritime influence on half moon island might have affected its development or establishment there. 10 d. schmitz et al. conclusions comparing the plant communities of the ice-free areas on half moon island with those described at stinker point, elephant island, by pereira & putzke (1994), rip point, nelson island, by putzke et al. (1998), the region of arctowski, admiralty bay, king george island by victoria et al. (2009), hennequin point, king george island, by victoria et al. (2013), demay point, king george island, by pereira et al. (2010) and keller peninsula, king george island, by pereira et al. (2007), it was possible to make the following conclusions. moss turf communities were found only in a small area and were difficult to clarify on account of the absence of key species in these communities. for example, chorisodontium aciphyllum (hook. f. & wills.) broth and polytrichum juniperinum hedw. are considered the moss tuft species most observed in this type of formation, but they were not found on half moon island. we found only polytrichastrum alpinum hedw., but its low coverage and frequency made it extremely difficult to define this community based on this species in this study. however, the physiognomy observed in these small sites allow us to suggest the occurrence of this formation on the island. among the flowering plants, only deschampsia antarctica was found on half moon island, while colobanthus quitensis (caryophyllaceae) was absent, in spite of its occurrence in the surrounding islands. because of the scarcity of soil on the island, the grass d. antarctica presented low coverage and low ecological importance indices. ornithocoprophobous species are rare on half moon island on account of guano inputs, as is the case on almost all islands in this region. polytrichum juniperinum and placopsis antarctica d.j. galloway, lewis-sm. & quilhot. were absent. the ornithocoprophilous lichen community is restricted to the eastern extremity of the island, the penguin rockeries are, and to the north-east cliffs, where cape petrels are found. the crustose lichen community is well represented on half moon island, since there are many areas where these lichens completely cover rock fragments. disclosure statement no potential conflict of interest was reported by the authors. funding this work was supported by the brazilian antarctic program through the national council for research and development (cnpq; process no. 574018/2008), the research foundation of the state of rio de janeiro (faperj; process e-26/170.023/2008), the ministry of science, technology and innovation (mcti), the interministerial commission for sea resources (cirm), and the foundation for research support of rio grande do sul state (fapergs), from which the authors appreciate the financial and logistic support that was needed to carry out this work. we also would like to acknowledge the argentine camara base crew, under the command of capitán de corbeta de infantería de marina hector daniel baez mannino, and thank the argentine antarctic program for the facilities arranged for us during our stay on half moon island. orcid daniela schmitz http://orcid.org/0000-0002-3162-2430 margéli pereira de albuquerque http://orcid.org/00000002-8945-5030 adriano luis schünemann http://orcid.org/0000-00017227-7074 filipe de carvalho victoria http://orcid.org/0000-00028580-1813 antônio batista pereira http://orcid.org/0000-00030368-4594 references allen s.e., grimshaw h.m. & holdgate m.w. 1967. factors affecting the availability of plant nutrients on an antarctic island. the journal of ecology 55, 381–396. bender n.a., crosbie k. & lynch h.j. 2016. patterns of tourism in the antarctic peninsula region: a 20-year analysis. antarctic science 28, 194–203. braun-blanquet j. 1964. pflanzensoziologie. (phytosociology.) 3rd ed. vienna: springer. chwedorzewska k.j., giełwanowska i., szczuka e. & bochenek a. 2008. high anatomical and low genetic diversity in deschampsia antarctica desv. from king george island, the antarctic. polish polar research 29, 377–386. edwards j.a. & lewis-smith r.i. 1988. photosynthesis and respiration of colobanthus quitensis and deschampsia antarctica from the maritime antarctic. british antarctic survey bulletin 8, 43–63. emslie s.d., polito m.j., brasso r., patterson w.p. & sun l. 2014. ornithogenic soils and the paleoecology of pygoscelid penguins in antarctica. quartenary international 352, 4–15. esponda c.m.g., coria n.r. & montalti d. 2000. breeding birds at halfmoon island, south shetland islands, antarctica, 1995/96. marine ornithology 28, 59–62. favero m. & silva m.p. 1991. the status of the breeding birds at halfmoon island (isla media luna) south shetland islands, antarctica. contribuciones del instituto antártico argentino 407, 1–8. hill p.w., farrar j., roberts p., farrell m., grant h., newsham k.k., hopkins d.w., bardgett r.d. & jones d.l. 2011. vascular plant success in a warming antarctic may be due to efficient nitrogen acquisition. nature climate change 1, 50–53. lara f. & mazimpaka v. 1998. sucession of epiphytic bryophytes in quercus pyrenaica forest from spanish central range (iberian peninsula). nova hedwigia 67, 125–138. leishman m.r. & wilde c. 2001. vegetation abundance and diversity in relation to soil nutrients and soil water content in vestfold hills, east antarctica. antarctic science 13, 126–134. polar research 11 lindsay d.c. 1971. vegetation of the south shetland islands. british antarctic survey bulletin 25, 59–83. ludwig j.a. & reynolds j.f. 1988. statistical ecology. new york: john wiley & sons. marques j., hespanhol e., vieira c. & séneca a. 2005. comparative study of the bryophyte epiphytic vegetation in quercus pirenaica and quercus robur woodlands from northern portugal. boletín de la sociedad española de briología 26–27, 75–84. moore d.m. 1970. studies in colobanthus quitensis (kunth) bartl. and deschampsia antarctica desv. ii. taxonomy, distribution and relationships. british antarctic survey bulletin 23, 63–80. ochyra r. 1998. the moss flora of king george island, antarctica. kracow: institute of botany, polish academy of science. ochyra r., lewis-smith r.i. & bednarek-ochyra h. 2008. the illustrated moss flora of antarctica. new york: cambridge university press. olech m. 2004. lichens of king george island antarctica. krakow: institute of botany, jagiellonian university. olrog c.c. 1958. observaciones sobre la avifauna antártica y de alta mar desde el río de la plata hasta los 60° de latitude sur. (observations on antarctic and high seas avifauna from el río de la plata to 60° south latitude.) acta zoologica lilloana 15, 19–33. øvstedal d.o. & lewis-smith r.i. 2001. lichens of antarctica and south georgia: a guide to their identification and ecology. cambridge: cambridge university press. øvstedal d.o. & lewis-smith r.i. 2004. additions and corrections to the lichens of antarctica and south georgia. cryptogamie, mycologie 25, 323–331. øvstedal d.o. & schaefer c.e.g.r. 2013. a new lichen species from the heritage range, ellsworth mountains, antarctica. hoehnea 40, 361–364. parnikoza i.y., maidanuk d.n. & kozeretska i.a. 2007. are deschampsia antarctica desv. and colobanthus quitensis (kunth) bartl. migratory relicts? cytology and genetics 41, 226–229. peet r.k. 1974. the measurement of species diversity. annual review of ecology and systematics 5, 285–307. pereira a.b. & putzke j. 1994. floristic composition of stinker point, elephant island, antarctica. korian journal of polar research 5, 37–47. pereira a.b., francelino m.r., stefenon v.m., schünemann a.l. & roesch l.f. 2010. plant communites from icefree areas of demay point, king george island, antarctica. in y.y. valentin et al. (eds.): annual activity report 2010. pp. 58–62. rio de janeiro: national institute of science and technology. pereira a.b., spielmann a.a., martins m.f.n. & francelino m.r. 2007. plant communities from ice-free areas of keller península, king george island, antarctica. oecologia brasiliensis 11, 14–22. pinto g.n., albuquerque m.p., victoria f.c. & pereira a.p. 2013. phytosociological study in ice-free areas of arctowski region, admiralty bay, king george island, antarctica. in y.y. valentin et al. (eds.): annual activity report 2013. pp. 45–47. rio de janeiro: national institute of science and technology. pitkanen s. 1998. the use of diversity indices to assess the diversity of vegetation in managed boreal forest. forest ecology and management 112, 121–137. putzke j. & pereira a.b. 2001. the antarctic mosses with special reference to the south shetlands islands. canoas, brazil: editora da ulbra. putzke j., pereira a.b. & putzke m.t.l. 1998. moss communities of rip point in northern island, south shetland islands, antarctica. pesquisa antártica brasileira 3, 104–115. redon j. 1985. liquens antárticos. (antarctic lichens.) santiago del chile: instituto antártico chileno. simas f.n.b., schaefer c.e.g.r., albuquerque-filho m.r., francelino m.r., filho e.i.f. & da costa l.f. 2008. genesis, properties and classification of cryosols from admiralty bay, maritime antarctica. geoderma 144, 116– 122. smykla j., wolek j. & barcikowski a. 2007. zonation of vegetation related to penguin rookeries on king george island, maritime antarctic. arctic, antarctic and alpine research 39, 143–151. teixeira c.r.s.l. 2010. bacterial diversity in rhizosphere soil from antarctic vascular plants of admiralty bay, maritime antarctica. the isme journal 4, 989–1001. teixeira l.c.r.s., yeargeau e., balieiro f.c., piccolo m.c., peixoto r.s., greer c.w. & rosado a.s. 2013. plant and bird presence strongly influences the microbial communities in soils of admiralty bay, maritime antarctica. plos one 8(6), e66109, doi: 10.1371/journal.pone.0066109. vera m.l. 2011. colonization and demographic structure of deschampsia antarctica and colobanthus quitensis along an altitudinal gradient on livingston island, south shetland islands, antarctica. polar research 30, article no. 7146, doi: 10.3402/polar. v30i0.7146. victoria f.c., albuquerque m.p., pereira a.b., simas f.n.b., spielmann a.a. & schaefer c.e.g.r. 2013. characterization and mapping of plant communities at hennequin point, king george island, antarctica. polar research 32, article no. 19261, doi: 10.3402/polar.v32i0.19261. victoria f.c. & pereira a.b. 2007. índice de valor ecológico (ies) como ferramenta para estudos fitossociológicos e conservação das espécies de musgos na baía do almirantado, ilha rei george, antártica marítima. (index of ecological significance [ies] as a tool for phytosociological studies and conservation of moss species in admiralty bay, king george island, maritime antarctica.) oecologia brasiliensis 11, 50–55. victoria f.c., pereira a.b. & costa d.p. 2009. composition and distribution of moss formations in the ice-free areas adjoining the arctowski region, admiralty bay, king george island, antarctica. iheringia, série botanica 64, 81–91. 12 d. schmitz et al. https://doi.org/10.1371/journal.pone.0066109 https://doi.org/10.3402/polar.v30i0.7146 https://doi.org/10.3402/polar.v30i0.7146 https://doi.org/10.3402/polar.v32i0.19261 abstract introduction materials and methods results fruticose lichen community moss carpet community muscicolous lichen community crustose lichen community moss turf community discussion conclusions disclosure statement funding references synergistic effects of an oil dispersant and low temperature on the freezing tolerance and solute concentrations of the blue mussel (mytilus edulis l.) arne vollan aarset and karl erik zachariassen aarset, a . v. & zachariassen, k. e. 1983: synergistic effects of an oil dispersant and low temperature on the freezing tolerance and solute concentrations of the blue mussel (mytilus edulis l). polar research 1 n . s . , 22s229. exposure of blue mussels (mytilus edulis l.) to an oil dispersant in increasing concentrations caused increased degree of injury in the mussels. the oil dispersant seemed to affect mechanisms responsible for the distribution of inorganic ions (na+, k + , cl-) and free amino acids across the cell membranes. the dispersant caused a marked reduction in the ability of the mussels to survive freezing at -10°c. freezing also caused more pronounced alterations in the transmembrane ionic distributions observed following exposure to the dispersant. this may indicate that the injuries caused by freezing are qualitatively the same as those caused by exposure to the dispersant alone, but brought into more extreme conditions. thus, freezing appears t o potentiate the effect of environmental pollutions by concentrating them in the fluid fraction of the frozen body fluids. arne vollan aarset and karl erik zachariassen, department of zoology, university of trondheim. 7055 draguoll, norway. introduction in many oil spills detergents or emulsifiers have been used to help disperse the oil. several studies have shown that the dispersing agents may cause more damage to living organisms than the oil itself (george 1961; nelson-smith 1968; odum et al. 1974). little is known, however, about the effects of oil dispersants on the abilities of littoral organisms to tolerate variations of natural ecological parameters such as temperature. in the north atlantic region sessile littoral molluscs like the blue mussel mytilus edulis are frequently exposed to air temperatures down to -20°c at low tide in winter (kanwisher 1955). as demonstrated by kanwisher (1955), cold exposure during low tide will be accompanied by freezing of the extracellular body fluid of mytilus. the ability of the blue mussel to tolerate low temperatures in a frozen state is correlated with the salinity to which the mussels are acclimated, so that the cold-hardiness increases with increas ing salinities (williams 1970). lange (1963) showed that acclimation to high salinities is accompanied by increases in the intracellular con centrations of free amino acids and other nin hydrin positive substances, which constitute up to about 50% of the intracellular solutes of mytilus. williams (1970) suggested that the intra cellular amino acids might have a cryoprotective effect in these bivalves, and that this may be the basis of the high cold-hardiness of mussels acclimated to high salinities. the purpose of the present study has been to investigate to what extent an oil dispersant in sublethal concentrations alters the concentrations of inorganic ions and free amino acids in mytilus edulis and the ability of the mussels to tolerate cold-exposure at low tide in winter. the study has been carried out in the laboratory by exposing m . edulis to sea water mixed with the dispersant and observing the effect on their cold-hardiness and the concentrations of free amino acids and inorganic ions in the body fluid compartments by comparison with the corresponding values of a control group kept in unpolluted sea water. materials and methods specimens of myfilus edulis l. (length 5-7cm) were collected in the intertidal zone in verra fjorden, county of s@r-trondelag, norway, in october 1981. the animals were transported within thermos bottles to the laboratory, where they were acclimated for 3-4weeks at 5 4 ° c to 224 arne vollan aarset & karl erik zachariassen a salinity of 30% using an aquarium system with recirculating sea water. t h e sea water was aerated and filtered through an eheim filter unit consisting of two mechanical filters with different pore sizes and an adsorptive charcoal filter. t h e sea water flow was maintained at approximately 3.0 i/min. the animals were not fed during the experiment. acute toxicity test groups of animals. each of nine mussels, were transferred from the acclimation bath to baths containing different concentrations of the oil dis persant finasol osr-5, kept in aerated glass aquaria. t h e oil dispersant was dissolved in 30% sea water at 5-6"c, and dispersant concen trations of 50, 100. 300. 500. and 1000 ppm were used t o determine the toxicity (ec 50). t h e experiment lasted for 150 h and the effects were continuously recorded during the test. a control group of mussels were kept in unpolluted sea water (30%) at the same temperature. t h e experimental media were changed every day. two parallel experimental series were run. o n e problem in using adult mussels in toxicity studies is the tendency of the animals t o close their shells when stimulated by an obnoxious sub stance (simpson 1968; crapp 1971). to ensure that the mussels were exposed to the experimental medium, the mantle cavities were flushed and refilled with the surrounding medium at the beginning of each experiment. the effects of exposure t o the dispersant were quantified according to behavioural criteria. when a normal submersed mussel is touched, it will respond by contracting its adductor muscles andclosing the valves (swedmark et al. 1971; lee et al. 1972; fossato & canzonier 1976). t h e loss of ability to close the valves when t h e clams were touched by a glass rod was used in the present study as 'injury' criterion. the shells were also classified as 'injured' if the shell opening remained wider than about 1 m m after a closing response. mussels that did not show any degree of injury after the toxicity test were selected for the freezing experiments. freezing experiments under natural conditions the mantle cavity is filled with sea water during freezing (williams 1970); similar conditions were used in the present experiments. to accomplish this the shells were kept permanently closed by means of rubber strings when removed from t h e experimental medium. t h e mussels were transferred to air filled pvc-bottles, which were immersed in a n ethanol/water cooling bath. t h e bath tempera ture could be regulated within ? 0.05"c. t h e animals were exposed t o -10°c for 1 2 h ; the mussels were then taken o u t of t h e bottles and transferred back t o their respective experimental media. t h e mussels were observed every hour to ascertain the effect of the freezing. samples of haemolyrnph and tissue samples of haemolymph (0.5-1 ml) were taken by means of a syringe from the pallial sinus (bayne et al. 1976). t h e haemolymph was centrifuged and the supernatant stored at -25°c. t h e pos terior adductor muscle was then dissected o u t and cut in three parts for analysis of intracellular free amino acids, inorganic ions and relative water content. amino acids t h e concentrations of free amino acids in muscle tissue (mmole/kg tissue water) and haemolymph (mmoles/kg plasma) were determined as taurin equivalents of free ninhydrin positive substances (nps) according to a method described by moore & stein (1948. 1954). osrnolality t h e osmolality of the body fluids was determined by measuring the melting point of 50 1.11 samples of haemolymph on a knauer osmometer. inorganic ions t h e concentration of chloride was determined by using a radiometer chloride titrator. t h e chloride concentrations in haemolymph were determined directly with the samples of haemolymph, whereas the chloride concentration in muscle tis sue was determined after acid extraction in hno, of pre-weighed tissue fragments (whittam 1955; little 1964: lutz 1972; aarset & zachariassen 1982). the content of cations was determined o n a perkin elmer 303 atomic absorbtion spectro photometer. t h e contents of na' and k' in t h e haemolymph were determined after dilution with synergistic effects of oil dispersant and low temperature 225 deionized water in order to make use of the optimum range of the spectrophotometer. the concentrations of monovalent ions in muscle tis sues were determined on the same tissue frag ments as those used for the chloride determina tions. standard solutions were prepared according to the perkin elmer manual. to obtain correct values for the intracellular concentrations in muscle tissue, the values were corrected for ions present in the extracellular tissue fluid. according to williams (1970), the extracellular space of the posterior adductor muscle of mytilus amounts to about 10% of the total muscle tissue fluid, and this value was used for the corrections in the present study. relative water content of muscle tissue the relative water content of the muscle tissue was determined by drying pre-weighed muscle fragments to constant weight at + 105°c. results acute toxicity tests and freezing tolerance table 1 summarizes the effects of the oil disper sant (finasol osr-5) on the ability of the mussel mytilus edulis to close the shells before and after exposure to 10°c. the 150 h-median effective concentration (ec50) as calculated by probit analysis (finney 1971) is about four times higher than the ec50-value obtained after 1 h recovery following the freezing stress. during recovery of the mussels the ec50 value increases and is 100 ppm higher after a recovery period of 3 h. a period of 3 h was used because this seems to be sufficient for unpolluted mussels to recover (aar set & zachariassen 1982). this demonstrates that mussels exposed to subfreezing temperatures after pollution are significantly more sensitive to the pollutant than unfrozen mussels. table 1. concentrations (ec-50) of an oil dispersant (finasol osr-5) affecting shell closure of the mussel m. edulis before and after a freezing stress. recovery time after 12 h acute toxicity test freezing at 10°c 150 h l h 2 h 3 h 195 ppm 200ppm 234pprn 300ppm inorganic ions and osmolality figure 1 shows the concentrations of inorganic ions and the osmolality in haemolymph of frozen and unfrozen specimens of m. edulis exposed to various concentrations of the dispersant. there were no significant changes in haemolymph osmolality (fig. l a ) at any of the concentrations of the dispersant (student's t-test). figure l b shows that haemolymph concentra tions of na' decrease significantly with increasing concentrations of the dispersant, except for unfrozen mussels exposed to 500 ppm. there was also a significant difference in na+ concentrations between frozen and unfrozen mussels at 300 and 500ppm, with the lowest values in the haemo lymph of the frozen animals. figure l c shows that haemolymph concentra tions of potassium do not change significantly i n any of the mussels, but the values are somewhat fluctuating in most of the experimental groups. figure id shows that haemolymph concentra tions of chloride are significantly lower in mussels exposed to 1000 ppm dispersant than in unpol luted mussels. figure 2 shows the concentrations of inorganic ions in the posterior adductor muscle of frozen and unfrozen mussels exposed to various con centrations of the dispersant. separate plots are given for the ionic concentrations of injured speci mens (frozen and unfrozen) and those that appear to be unaffected by the pollution. figure 2a shows that concentrations of na' increase significantly with increasing concentra tions of the dispersant. there was also a sig nificant difference in na+ concentrations between frozen and unfrozen mussels at the two highest concentrations of the dispersant, frozen mussels having the highest values. the concentrations of na' in the muscles of injured animals (fig. 2a) are markedly elevated compared to the concen trations in normally behaving mussels, which seem to be rather constant and not significantly different from those of unpolluted mussels. figure 2b shows that the intracellular concen trations of potassium decrease significantly with increasing concentrations of the dispersant. there was also a significant difference in k + concentra tions between frozen and unfrozen animals at the two highest concentrations of the dispersant, the lowest values being found in the frozen mussels. the concentrations of k' in the muscles of injured animals are significantly lower than cor responding concentrations in normally behaving 226 arne vollan aarset & karl erik zachariassen 400 m. 0 y i i 5 i 6 5 1 1 l i i 1 0 50 100 3oo 500 iom) e x posure conc.(f'pm) fig. 1. concentrations of inorganic ions and osmolality in the haemolymph of frozen (-10°c w ) and unfrozen ( + 5 t ci) specimens of m. edulis exposed to various concentrations of the dispersant. 2 0 0 1 i00 0 ux) 200 100 0 i50 1w 50 50 0 u10 200 i00 0 300 200 i c l l 0 k' i ci 6 1 5 ? exposure conc(pph) fig. 2. concentrations of inorganic ions in the posterior adduc tor muscle of frozen ( 10°c w) and unfrozen (+yc 0 ) speci mens of m. edulis exposed to various concentrations of the dispersant. separate plots are given for injured (8) and unaf fected (0) mussels. the standard deviation and the numbers of individuals are indicated on the top of each bar. synergistic effects of oil dispersant and low temperature 227 mussels. in these mussels, however, the k+-con centrations decreased significantly with increasing concentrations of the dispersant. figure 2c shows that the intracellular concen trations of chloride in the posterior adductor muscle increase significantly with increasing con centrations of the dispersant. there are no sig nificant differences in chloride concentration between frozen and unfrozen animals, except for the mussels exposed t o 500 ppm finasol osr-5. the concentrations of chloride in the muscles of injured animals are significantly higher than the corresponding concentrations in normally behaving mussels. the chloride concentrations in the muscles of the latter animals were quite con stant and not significantly different from those of unpolluted animals. free amino acids (nps) figure 3 shows the concentrations of free amino acids (nps) in the posterior adductor muscle and 1 nps 6 5 5 4 5 1 0 50 100 3m 500 lml ’ exposure conc.iwh1 fig. 3. concentrations of free amino acids (nps) in the posterior adductor muscle and the haernolymph of frozen (-10°c w) and unfrozen (+k 0 ) specimens of m. edulis exposed to various concentrations of the dispersant. separate plots are given for injured (a) and unaffected ( 0 ) mussels. the haemolymph of frozen and unfrozen mussels exposed to various concentrations of the disper sant. the concentrations of injured (frozen and unfrozen) and uninjured (frozen and unfrozen) animals are plotted separately. figure 3a shows that the intracellular concen trations of free amino acids in the muscle of unfrozen animals exposed to 1000 ppm dispersant are significantly lower than those of unpolluted animals. there were also significantly lower nps con centrations in frozen than in unfrozen mussels. exceptions were the concentrations of animals exposed to the highest concentrations of the dispersant. animals classified as injured have significantly lower intracellular concentrations of free amino acids at all but the highest concentrations of the dispersant, where no difference could be found. figure 3b shows that the concentrations of free amino acids in the haemolymph of unfrozen animals are significantly higher in polluted mus sels, whereas no significant difference seems to exist between mussels in the various concentra tions of the dispersant. frozen mussels exposed to 0 and 100ppm have significantly higher con centrations of amino acids than unfrozen animals. there were no significant differences between the nps levels in any of the other groups. discussion the present results indicate that exposure to oil dispersant in increasing concentrations causes increasing degrees of injury in mytilus edulis mus sels. it is also evident that the dispersant affects mechanisms responsible for the distribution of inorganic ions and free amino acids across the cell membranes. the observed drop in haemolymph na+ con centration and increase in intracellular na+ con centration indicate that the dispersant affects either the cell membrane permeability to na+, the active transport system to na+ across the cell membranes, or the metabolic processes supplying energy to the active na+ pump system. if there were an effect on the transmembrane per meability, it would probably also take place in the membranes separating the haemolymph from the mantle fluid and cause a flux of na+ from the mantle fluid to the haemolymph, compensating the loss of na+ to the intracellular compartments. 228 arne vollan aarset & karl erik zachariassen the observed d r o p in haemolymph na' concen tration indicates that n o such compensatory rux has taken place; the possibility of an effect on the membrane permeability appears unlikely there fore. t h e present results allow no conclusion to be drawn as to whether there is a direct effect on the transport system or an indirect effect by inhibition of metabolism. a change in the distribution of an actively transported ion like na' across the cell mem branes is tilso likely t o alter the distribution of charged solutes like k' and ci-, by means of a gibbs donnan effect. this is likely to be the basis of the transmembrane distribution of k' and ci-. which in the present study is observed t o take place concomitantly with the change in the distribution of na'. a reduced transmembrane electrochemical potential difference of na' across the cell mem branes is likely to reduce the ability of the mussels to accumulate free amino acids in the intracellular compartments. in that this accumulation t o a great extent is assumed t o depend on a na' dependent transport system (pequignat 1973). t h e present study reveals n o significant drop in the intracellu lar concentration of free amino acids. except at the highest concentration of the dispersant. but the significant increase in the concentration of free amino acids in the haemolymph reveals that the transmembrane distribution of free amino acids is affected. it should here be kept in mind that because of the comparatively high concen tration of free amino acids in the intracellular compartments in relation to those in the hae molymph, even a very moderate reduction of the intracellular concentration may give rise to a marked increase in the concentration in the haemolymph. the present results reveal that an increasing concentration of oil dispersant causes a marked reduction in the ability of the mussels to survive freezing at -10°c. thus. exposure to the disper sant clearly reduces the freezing tolerance of the animals. freezing also causes the alterations in trans membrane ionic distributions observed following exposures to increasing concentrations of disper sant. to become more pronounced. this may indicate that the effects of freezing are quali tativelv the same as those caused by exposure to the dispersant alone. but brought into more extreme conditions. consequently, the present results d o not indicate that the oil dispersant reduces the freezing tolerance of the animals by affecting the special cold-hardening mechanisms of the animals. this conclusion is supported by the fact that all changes in solute concentrations became more extreme when they were calculated for injured animals separately, without regard t o whether the injured animals had been frozen or only exposed to the dispersant. as pointed o u t by aarset & zachariassen (1982), freezing is likely t o potentiate the effect of environmental pollutants by concentrating them in the fluid fraction of t h e frozen body fluids. this effect allows the pollutants t o act in injurious concentrations inside a frozen animal, although they occur in harmless levels in the environment and in unfrozen specimens. a mechanism of this kind might be the basis of the freezing induced injuries observed in m . edulis mussels in the pres ent study. following freezing the animals showed an increasing recovery with time. animals frozen in high concentrations of dispersant needed more thawing-time to recover than animals frozen in low dispersant concentrations. this implies that the injury concept is not easily defined, and that the time parameter has to be taken into consider ation in a manner which depends o n the dispersant concentration used. when dispersant is used to clean oil from beaches, animals may be exposed to undiluted dispersant and left in air until either the incoming tide or the use of water hoses wash off t h e con taminants. consequently, o n e should b e careful when drawing firm conclusions about the applicability of the present results in situations involving use of dispersant against oil spills. before such conclusions can be drawn, more studies are needed, both in t h e field where oil dispersants a r e used in combination with oil and in the laboratory. ackno4edgemenr. this study has been sponsored by the s o w e g i a n marine pollution research and monitoring pro xramme. the authors thank mrs. a . lohrmann for technical assistance. references aarset. a . v . & zachariassen. k. e . 1982: effects of oil pollution on the freezing tolerance and solute concentrations of the blue mussel (mytrlrcr e d u h l . ) . m o r . b i d . 72. 45-51. synergistic effects of oil dispersant and low temperature 229 bayne, b. l.. widdows, j. &thompson, r . i. 1976: physiology 11. pp. 207-260 in bayne, b. l. (ed.): marine mussels. their ecology and physiology. cambridge university press, cambridge. crapp, g . p. 1971: laboratory experiments with emulsifiers. in cowell. e. b . (ed.): the ecological effects o f o i l pollution on littoral communities. finney, d. j . 1971: probit analysis. cambridge university press, cambridge. fossato, v. u. & canzonier, w . j . 1976: hydrocarbon uptake and loss by the mussel m y t i h edulis. mar. biol. 36. 243 250. george, m. 1961: oil pollution of marine organisms. nature f l o n d o n ) 192, 1209. kanwisher. j. w. 1955: freezing in intertidal animals. biol. bull. 109. 5&63. lange, r . 1963: the osmotic function of amino acids and taurine in the mussel mytilusedulis. comp. biochem. physiol. 10. 173-179. lee, r. f., sauerheber, r. & benson, a. a . 1972: petroleum hydrocarbons: uptake and discharge by the marine mussel mytilus edulis. science, n . y. 177, 344-346. little, j . r . 1964: determination of water and electrolytes in tissue slices. analyt. biochem. 7. 87-95. lutz, p t. 1972: extracellular spaces and composition of vari ous tissues of perch. comp. biochem. physiol. 41a, 77-88. moore, s. & stein, w. h. 1948: photometric ninhydrin method for use in the chromatography of amino acids. j. biol. chem. 176. 361-388. moore, s . & stein, w. h. 1954: a modified ninhydrin reagent for the photometric determination of amino acids and related compounds. j. b i d . chem. 211, 907-913. nelson-smith, a . 1968: the effects of oil pollution and emul sifier cleansing on shore life in south-west britain. j . appl. odum. h. t . , copeland, b. j . & mahan, e. a. 1974: coastal ecological systems of the united states. vol. i l l . conserv. found.. washington, d.c. pequignat, e. 1973: a kinetic and autoradiographic study of the direct assimilation of amino acids and glucose by organs of the mussel mylilus edulis. mar. biol. 19, 227-244. simpson, a. c. 1968: oil, emulsifier and commercial shellfish. pp. 1-91 in carthy, j . d. & arthur, d. r. (eds.): the biological effects of oil pollution on littoral communities. field studies council. swedmark, m. b.. emanuelsson. e . & granmo, a . 1971: biological effects of surface active agents on marine animals. mar. b i d . 9. 183-201. whittam, r . 1955: a conventional micromethod for the esti mation of tissue chloride. j. physiol. 120, 65. williams, r . j . 1970: freezing tolerance in mytilus edulis. comp. biochem. physiol. 35, 145-161. e d . 5 . 97-107. no job name metabolism and biomass vertical distribution of zooplankton in the bransfield strait during the austral summer of 2000por_116 415..425 lidia yebra,1,2 santiago hernández-león,2 carlos almeida2 & pierrick bécognée2 1 institut de ciències del mar, csic, passeig marítim de la barceloneta 37–49, es-08003 barcelona, spain 2 biological oceanography laboratory, facultad de ciencias del mar, universidad de las palmas de gran canaria, campus universitario de tafira, es-35017 las palmas de gran canaria, canary islands, spain abstract the vertical distribution (0–550 m) of zooplankton biomass, and indices of respiration (electron transfer system [ets]) and structural growth (aminoacyltrna synthetases activity [aars]), were studied in waters off the antarctic peninsula during the austral summer of 2000. the dominant species were the copepod metridia gerlachei and the euphausiid euphausia superba. we observed a vertical krill/copepod substitution in the water column. the zooplankton biomass in the layer at a depth of 200–500 m was of the same magnitude as the biomass in the layer at a depth of 0–200 m, indicating that biomass in the mesopelagic zone is an important fraction of the total zooplankton in antarctic waters. the metabolic rates of the zooplankton community were sustained by less than 0.5% of the primary production in the area, suggesting that microplankton or small copepods are the main food source. neither food availability nor predation seemed to control mesozooplankton biomass. the wide time lag between the abundance peak of the dominant copepod (m. gerlachei) and the phytoplankton bloom is suggested to be the main explanation for the low summer zooplankton biomass observed in these waters. keywords aars; antarctic peninsula; biomass; ets; metabolism; zooplankton. correspondence lidia yebra, institut de ciències del mar, csic, passeig marítim de la barceloneta 37–49, es-08003 barcelona, spain. e-mail: lyebra@icm.csic.es doi:10.1111/j.1751-8369.2009.00116.x the bransfield strait is located between the south shetland islands and the antarctic peninsula. it presents high variability in both physical conditions (e.g., mesoscale eddies and fronts; zhou et al. 2006) and primary production rates (basterretxea & arístegui 1999; varela et al. 2002; morán et al. 2006). it is also considered to be a highly productive region for all trophic levels (huntley et al. 1990; zhou et al. 1994). the studies of antarctic zooplankton have focused on estimating the impact of these organisms on the development and evolution of primary production in areas affected by strong microor mesoscale plankton distribution patterns, or by the influence of eddies and frontal systems, which are characteristic features of the southern ocean. more recently, the influence of the physical environment on zooplankton species distribution, as well as their role in energy flow, has been studied using indices of physiological processes (bergeron et al. 1985; schalk 1990; drits et al. 1993; hernández-león et al. 1999; hernández-león et al. 2000). however, not all the variability in zooplankton biomass is explained by physical changes. zooplankton biomass and abundance in the bransfield strait have been studied during the austral spring and summer seasons (alcaraz et al. 1998; hernández-león et al. 1999; hernández-león et al. 2000; cabal et al. 2002; calbet et al. 2005), showing a great interannual variability. previous studies (hernández-león et al. 1999; hernández-león et al. 2000; calbet et al. 2005) have reported low mesozooplankton biomass around the antarctic peninsula. this is probably related to predation and/or food quality, rather than to food availability. hernández-león et al. (2000) studied the distribution of mesozooplankton biomass and metabolism in the upper 200-m layer, showing low zooplankton biomass with a rather high growth rate. yet, zooplankton consumed less than 10% of the primary production, and a top–down effect of krill on copepods in the area was suggested. in addition, an important fraction of the biomass in these waters was found in the mesopelagic zone (below 200-m depth), as was observed in previous works on antarctic copepods (lancraft et al. 1989; lancraft et al. 1991; lopez & huntley 1995; pakhomov et al. 1996; lancraft et al. polar research 28 2009 415–425 © 2009 the authors 415 mailto:lyebra@icm.csic.es 2004) and euphausiids (hernández-león, portillohahnefeld et al. 2001; hernández-león & montero 2006). however, most studies to date have been focused on the upper 200-m layer. the study of biomass and diel vertical migration of the deep-water mesozooplankton (200–550-m depth) could improve our understanding of the trophic web in this region of the southern ocean. the main aim of this study is to give a first insight on zooplankton biomass and metabolic rates in relation to the vertical distribution over the 0–550-m water column. we used two enzymatic methods to obtain highresolution estimates of respiration and growth at depth. the activity of the electron transfer system (ets; packard 1971) was used to assess the maximum potential respiration. the aminoacyl-trna synthetases activity (aars; yebra & hernández-león 2004) was applied as an index of the in-situ growth rate. the combined use of these methods allowed us to simultaneously study in-situ respiration and growth rates of mixed zooplankton populations inhabiting mesopelagic depths, without the need for incubation or elaborate procedures. a recent discussion of the usefulness and advantages of these biochemical methods can be found in båmstedt (2000), ikeda et al. (2000), hernández-león, almeida et al. (2001, 2002), yebra, harris et al. (2005), yebra et al. (2006) and guerra (2006). secondarily, we seek to investigate the importance of bottom–up and top–down controls on zooplankton biomass in the bransfield strait. finally, despite the short austral summer nights, we studied the plankton dynamic in the water column by day and night in an attempt to look at diel vertical migration and carbon fluxes mediated by zooplankton in the region. methods sampling during the austral summer of 2000, from 24 january to 17 february, 10 stations were sampled on board the rv bio hespérides in the bransfield strait, antarctic peninsula (fig. 1), using a longhurst–hardy plankton recorder (lhpr; 200-mm mesh net). the average day length was 20 h (06.00–02.00 h gmt), and darkness lasted for only 4 h (02.00–06.00 h gmt). eight hauls were carried out by day (14.33–24.21 h gmt) and two hauls were carried out at night (03.56–04.39 h gmt), in order to study diel fig. 1 location of the longhurst–hardy plankton recorder net stations: �, day; �, night. antarctic summer zooplankton metabolism l. yebra et al. polar research 28 2009 415–425 © 2009 the authors416 differences in biomass and metabolic profiles. samples were collected from 550 to 0 m, at a speed of 3–4 knots. each haul contained about 22 samples, corresponding to different layers, ranging from 13to 24-m deep. a conductivity–temperature–depth (ctd) recorder was used to obtain high-resolution profiles of temperature, conductivity and fluorescence. on board, samples were split into two halves. one half was stored in liquid nitrogen at -196°c, for biochemical assays, and the other half was preserved in 4% formalin for presence/absence analyses of the two main groups found: euphausiids and copepods. biomass and metabolic rates frozen samples were homogenized with tris-hcl buffer (ph = 7.8) before the assays. the protein content was measured using the folin dye method (lowry et al. 1951), as modified for microanalysis by rutter (1967). we transformed biomass, measured as protein content, to carbon, using published ratios: protein : dry weight (dw) = 0.192; carbon : dry weight = 0.40 (postel et al. 2000). the ets activity was assayed using the method of packard (1971), as modified by gómez et al. (1996). ets activity was corrected for the in-situ temperature at each depth using the arrhenius equation with an activation energy of 15 kcal mol-1, as given by packard et al. (1975). aars activity was measured using the method of yebra & hernández-león (2004), and was corrected for the in-situ temperature with an activation energy of 10.5 kcal mol-1 (guerra 2006). the community respiration rates (r; mg c m-2 h-1) were assessed from specific ets activities (ml o2 mg prot-1 h-1) and integrated biomass (mg protein m-2), assuming a respiratory quotient of 0.97 (omori & ikeda 1984) and a theoretical r : ets ratio of 0.5 (hernándezleón & gómez 1996; ikeda et al. 2000). the community growth rates (nm ppi m-2 h-1) were calculated from specific aars activities (nm ppi mg protein-1 h-1) and integrated biomass (mg protein m-2). we assessed the community potential ingestion (i; mg c m-2 h-1) from respiration rates (r), assuming an assimilation and a gross growth efficiency of 70 and 30%, respectively, and applying the equation proposed by ikeda & motoda (1978): i = 100 r/(70 30) = 2.5 r. active flux protein content and ets activity data were averaged at 25-m intervals to obtain day and night vertical distribution profiles. the biomass night profile was then subtracted from the biomass day profile to show daily changes. the day-minus-night protein profile was integrated to estimate migrant biomass (mg protein m-2). the negative area values represent the migrant biomass that reached the euphotic layer at night (0–245-m depth). to assess the respiratory flux (ml o2 m-2 day-1) of carbon to deep waters, positive values of the ets (ml o2 m-3 h-1) day-minus-night profile were integrated and divided by the integrated biomass present in the same depth range (as in yebra, almeida et al. 2005). the specific ets activity measured at depth (ml o2 mg protein-1 h-1) was then multiplied by the migrant biomass (mg protein m-2) to obtain the flux resulting from migrants’ respiration located below 200-m depth during the day. for all calculations, we applied 4 h of darkness per day, and an r : ets ratio of 0.5 (see above). results hydrology we found no sea-ice cover during the sampling period. the water temperature ranged between 1 and 2°c at the surface, decreasing to -1°c at 500-m depth (fig. 2). we observed occasional deep warm water masses at a depth of 200 m. salinity ranged from 33.9 to 34.4 at the surface, but was similar below 100 m at all stations. the maximum of chlorophyll was observed at around 25-m depth, where values reached up to 14 mg chl. a m-3. zooplankton biomass the most abundant organisms were the pelagic copepod metridia gerlachei and the euphausiid euphausia superba. calanoides acutus and calanus propinquus were also present, but were found only in low numbers. visual assessments of the presence/absence of copepods and euphausiids showed that by day large euphausiids were in the surface waters (above 250-m depth), whereas smaller juveniles stayed at depth (500–550 m). m. gerlachei was located in a compact layer from 300 to 500 m depth. occasional layers of salps (salpa thompsonii) were also found around 100and 300-m depths (fig. 3a). surprisingly, the biomass values by day were similar in both the 0–200-m and the 200–550-m layers (t = -0.17, p = 0.86; table 1). at night, euphausiids were observed above 100 m and below 400 m, whereas copepods dominated the layer in between (150–400 m), and salps scarcely occurred above 100 m (fig. 3b). during the night, the biomass was concentrated in the upper 200-m layer, increasing by twofold compared with daytime values (t = 2.85, p < 0.01; table 1). metabolic indices during the day, specific ets activities decreased slightly from the surface down to 200 m, but presented higher antarctic summer zooplankton metabolisml. yebra et al. polar research 28 2009 415–425 © 2009 the authors 417 values at mesopelagic depths (200–550 m, t = -2.81, p < 0.01; fig. 3a). in contrast, specific aars activities were higher above 200 m (fig. 3a), with an averaged specific aars activity double that in the 200–550-m layer (t = 3.83, p < 0.001; table 1). at night, the specific ets remained variable, with peaks at 25and 225-m depths. specific aars activity peaks were also higher in the upper 250-m layer (fig. 3b). the upward diel migration was accompanied by a 60% increase in averaged specific ets activity in the upper 200 m (t = -2.78, p < 0.01), and a slight but not significant (t = 0.93, p = 0.35) 15% decrease between 200 and 550 m. the specific aars activity remained constant in shallow waters (t = 0.42, p = 0.67) and increased, although not significantly (t = -1.77, p = 0.079), by 46% in the mesopelagic zone at night (table 1). community rates and active flux considering the whole water column, we observed a small increase in specific ets and aars activities by night (13% and 9%, respectively; table 1). however, as the biomass also increased at night, the respiration rate of the community was 1.7 times higher during the night (0.20 mg c m-2 h-1) compared to daytime (0.12 mg c m-2 h-1). the community growth rate was also 50% higher by night (360.6 nm ppi m-2 h-1) than by day (241.8 nm ppi m-2 h-1). the mean community respiration (over 0–550 m) was 1.74 mg c m-2 day-1, and the community ingestion (0–550 m) assessed from respiration was 4.35 mg c m-2 day-1. from the day-minus-night biomass differences observed in the upper 250 m (fig. 4a) we obtained a daily migrant biomass of 92.3 mg protein m-2. the integrated total ets activity diel difference (fig. 4b) was 187.8 ml o2 m-2 h-1, and we estimated an active flux to deep waters of 10.2 mg c m-2 d-1. discussion relationship between biomass vertical distribution and enzyme activities the antarctic peninsula is a region of low zooplankton biomass in comparison with other antarctic areas (atkinson et al. 1997; ward et al. 1997; ward et al. 2004). the summer zooplankton biomass in the bransfield strait has high interannual variability, ranging from 35 up to 1039 mg c m-2 (table 2). the highest biomass record corresponds to a summer when the salp s. thompsonii was the most abundant zooplankton species (alcaraz et al. 1998). this species can have a widespread oceanic distribution further north and east of the study area (hosie 1994). however, they were scarcely found during our study, and were mainly associated with relatively warmer waters. instead, zooplankton was dominated by crustaceans, and the biomass values we observed were within the lower range of the previous values reported in the area (table 2). the patterns of zooplankton vertical distribution described for antarctic waters coincide with our observations in the bransfield strait. these studies show a surface layer dominated by krill, and a wide layer of smaller organisms below 200-m depth (pakhomov et al. 1994; murray et al. 1995; weeks et al. 1995; hernández-león, portillo-hahnefeld et al. 2001). during our sampling, fig. 2 daytime conductivity–temperature–depth (ctd) vertical profiles of temperature (°c), salinity and chlorophyll a (mg chl. a m-3). antarctic summer zooplankton metabolism l. yebra et al. polar research 28 2009 415–425 © 2009 the authors418 euphausiids (e. superba) were concentrated above 200 m and around 550-m depth. the copepod m. gerlachei was found in the 300–500-m layer, as previously observed (schnack-schiel & mújica 1994; lopez & huntley 1995; hernández-león, portillo-hahnefeld et al. 2001), and was the dominant copepod species during our sampling. this agrees with pakhomov et al. (2000), who observed that this copepod could make up 40–95% of the total abundance in the absence of krill swarms. despite the reduced krill presence below 200-m depth, the biomass in the mesopelagic zone was similar to that in upper waters. this is in agreement with studies showing that copepods could represent more than 50% of the total biomass in antarctic waters (boysen-ennen et al. 1991; conover & huntley 1991; pakhomov et al. 2000). the vertical distribution of ets activities was related to biomass concentrations. the highest specific respiration rates (ets activities) were found below 200 m, and were mainly related to copepod populations. because of the inverse allometric relationship between size and metabolism (ikeda 1985), copepods would show a higher metabolism than euphausiids, thereby explaining the observed tendency of specific respiration rates to increase with depth. specific ets activity increases in relation to high biomass values were previously observed in the weddell sea (jacques & panouse 1991; schnack-shiel & mújica 1994). the night-time increase in biomass from 0 to 200 m also corresponded to higher values of specific ets, and suggests that higher ingestion rates occur at night. enhanced feeding at night has been previously observed in antarctic waters. atkinson et al. (1996) observed higher grazing rates of copepods, and hernández-león, portillo-hahnefeld et al. (2001) found higher gut fullness of antarctic krill at night. opposite to fig. 3 (a) day and (b) night averaged vertical profiles (�sd) of biomass (mg protein m-3), specific electron transfer system (ets) activity (ml o2 mg protein-1 h-1) and specific aminoacyl-trna synthetases (aars) activity (nm ppi mg protein-1 h-1). biomass plots show the general vertical distribution of euphausiids (e), copepods (c) and salps (s). antarctic summer zooplankton metabolisml. yebra et al. polar research 28 2009 415–425 © 2009 the authors 419 respiration, the specific growth rates (aars activity) during the day in the upper 200 m were higher than in the mesopelagic layer. this indicates higher specific growth rates in the euphotic zone, where primary production was concentrated. also, specific aars activities did not increase at night, which suggests that although feeding seemed to have a day–night cycle, the somatic growth of the populations remained constant in the upper waters. control of zooplankton biomass one of the main unsolved questions in the region is which factors determine the low summer zooplankton biomass. we looked at zooplankton metabolic rates and food availability to discuss the importance of the bottom–up and top–down control of zooplankton populations. the community respiration in the 0–200-m layer (1.33 mg c m-2 day-1) was similar to the summer 1993 estimates in the bransfield strait (1.5 mg c m-2 day-1; hernández-león et al. 2000). however, in summer 1994, the biomass was dominated by salps, and the zooplankton carbon losses due to respiration ranged from 10 to 50 mg c m-2 day-1 (alcaraz et al. 1998). on the other hand, we found that respiration in the mesopelagic waters (200–550-m depth) was 30% higher than that in the euphotic zone (2.2 mg c m-2 day-1). when comparing the average respiration rate of the whole 0–550-m water column (1.74 mg c m-2 day-1) with the average primary production found in the area (2854.5 mg c m-2 day-1; agawin et al. unpubl. data; table 2), we observe that the zooplankton daily respiration needs accounted for only 0.06% of phytoplankton production. this value is much lower than the 0.9 and 5.3% reported for crustacean zooplankton and salps, respectively, by alcaraz et al. (1998). likewise, the average community ingestion (0–550 m) derived from respiration represented only 0.15% of the primary production. therefore, in our study, zooplankton metabolic requirements accounted for less than 0.3% of the photosynthetic production. this percentage is lower than that observed in previous studies (atkinson & shreeve 1995; lopez & huntley 1995; alcaraz et al. 1998; hernándezleón et al. 1999; hernández-león et al. 2000). however, it is important to note that the phytoplankton bloom in february 2000 was notably intense. the average chlorophyll a concentration varied from 3.16 � 1.5 mg chl. a m-3 (ranging from 0.38 to 16.75 mg chl. a m-3) in open water (agustí et al. 2004) to 19 � 5 mg chl. a m-3 within the waters of deception island (sturz et al. 2003). also, the primary production rate was the highest recorded in the area that we know of (table 2). the other important food source to consider for table 1 zooplankton biomass (mg protein m-3, except where otherwise noted), specific electron transfer system (ets; ml o2 mg protein-1 h-1) and specific aminoacyl-trna synthetases (aars; nm ppi mg protein-1 h-1) activities. potential respiration (mg c m-2 h-1) and ingestion (mg c m-2 h-1) rates calculated from specific ets activities and biomass. growth rates (nm ppi m-2 h-1) calculated from specific aars activities and biomass (see methods) for depths of 0–200, 200–550 and 0–550 m in the bransfield strait. depth range (m) day night mean � sd (number of samples) range mean � sd (number of samples) range biomass 0–200 0.23 � 0.61 (62) 0.001–4.68 0.54 � 0.39 (21) 0.05–1.56 200–550 0.24 � 0.20 (59) 0.004–0.86 0.25 � 0.32 (28) 0.03–1.71 average 0–550 0.24 � 0.46 (121) 0.37 � 0.38 (49) total 0–550 0.52/130.0* (121) 1.23/179.4* (49) specific ets 0–200 3.12 � 2.03 (76) 0.04–10.86 4.99 � 4.21 (21) 1.05–21.19 200–550 4.23 � 2.69 (83) 0.54–14.18 3.63 � 3.63 (28) 0.51–20.10 average 0–550 3.70 � 2.45 (159) 4.20 � 3.90 (49) specific aars 0–200 2.49 � 2.28 (62) 0.11–11.36 2.23 � 2.00 (18) 0.03–7.33 200–550 1.26 � 1.70 (65) 0.08–7.87 1.84 � 1.83 (24) 0.07–9.28 average 0–550 1.86 � 1.90 (127) 2.01 � 1.89 (42) potential respiration 0–200 0.037 0.140 200–550 0.092 0.083 average 0–550 0.065 � 0.039 0.111 � 0.041 potential ingestion 0–200 0.093 0.350 200–550 0.231 0.206 average 0–550 0.162 � 0.197 0.278 � 0.102 growth 0–200 114.54 240.84 200–550 105.84 161.00 average 0–550 110.19 � 6.15 200.92 � 56.46 * mg protein m-2. antarctic summer zooplankton metabolism l. yebra et al. polar research 28 2009 415–425 © 2009 the authors420 mesozooplankton is microplankton. e. superba is known to feed on ciliates as well as copepods (price et al. 1988; froneman et al. 1996; atkinson & snyder 1997; perissinotto et al. 2000; wickham & berninger 2007). likewise, m. gerlachei has shown preference for ciliates and other copepods over algae, in both austral autumn and winter (atkinson 1996, 1998; pasternak & schnack-schiel 2001; wickham & berninger 2007). calbet et al. (2005) suggested that, in this region, the mesozooplankton was grazing on microplankton rather than on phytoplankton, and was therefore aiding the development of the phytoplankton bloom. nevertheless, the net microplankton production found (76.36 mg c m-3 day-1; agustí et al. 2004) was much higher than the phytoplankton production (4.6 mg c m-3 day-1; agawin, unpubl. data), although it was similar to the value found in a previous study in the region (93.35 mg c m-3 day-1; arístegui et al. 1996). therefore, the mesozooplankton metabolism during summer 2000 was not limited by phytoor microplankton availability. hence, as previously suggested (hernández-león et al. 1999), we reject the bottom–up control hypothesis. on the other hand, a top–down effect of krill on copepods has been suggested as the main factor controlling copepod abundance and development in the bransfield strait (hernández-león et al. 1999; hernández-león et al. 2000; hernández-león, portillo-hahnefeld et al. 2001). this idea is supported by the inverse relationship of krill/non-krill zooplankton distribution observed here, and in other antarctic areas, where high krill densities coincide with very low copepod abundances (hosie 1994; voronina et al. 1994; atkinson et al. 1999). as mentioned above, krill is able to prey selectively on copepods (price et al. 1988; graneli et al. 1993; atkinson & snyder 1997), although their impact on copepods might be reduced in spring or summer, when phytoplankton concentrations are high. hernández-león, portillo-hahnefeld et al. (2001) observed that during the austral summer of 1993 e. superba grazed on phytoplankton by day, but, despite the high primary production (basterretxea & arístegui 1999; table 2), they switched to feed on m. gerlachei at night, when copepods migrated upwards. our study reflected a similar scenario, with zooplankton biomass in the lower range and a high primary production. hence, the low biomass found could be the result of predation pressure (top–down control). however, as a result of the short length of the summer night and the high phytoplankton concentrations available to krill during the bloom, their impact on copepods would be minimal. thus, predation might not be the only cause for the low zooplankton biomass in the bransfield strait, and copepod life history might be an important factor to explain the low values found in summer. ward et al. (2004) suggested that the low biomass found was probably linked to the higher latitude, lower temperatures and reduced production in comparison with areas further north. this combination could delay the development of zooplankton populations. this agrees with studies of m. gerlachei showing that their abundance peaks in autumn, i.e., march–may (schnack-schiel & hagen 1994, 1995; tucker & burton 1990) or in early winter, i.e., june (king & lacasella 2003). king & lacasella (2003) found the biomass of m. gerlachei in the waters of deception island (bransfield strait) to be 1.7 mg dw m-3 during february 2000, which is similar to the biomass that we observed in open waters at that time (1.2 mg dw m-3). nevertheless, the biomass they found in june (31.4 mg dw m-3) was 20 times greater, showing a four-month lag response of the copepod population to the phytoplankton bloom. this may be explained by their preference for microplankton and small copepods (i.e., oithona spp.) as prey, the populations of which would peak after the phytoplankton bloom. therefore, it is probable that the low zooplankton biomass found in summer is not caused by predation pressure either, but instead is the result of life-cycle fig. 4 day-minus-night averaged value profiles of (a) biomass (mg protein m-3) and (b) total electron transfer system activity (ets; ml o2 m-3 h-1). antarctic summer zooplankton metabolisml. yebra et al. polar research 28 2009 415–425 © 2009 the authors 421 adaptation of the dominant copepod species to the production dynamics in the region. vertical migration and carbon fluxes biomass in the upper 200-m layer increased by twofold at night, corresponding to the upward migration of m. gerlachei (park & wormuth 1993; lopez & huntley 1995; hernández-león, portillo-hahnefeld et al. 2001; king & lacasella 2003). however, the integrated migrant biomass in the bransfield strait was low (192.0 mg c m-2), compared with previous studies in the area (voronina et al. 1994; hernández-león et al. 2000), and was within the lower range (20–5200 mg c m-2) of values found in antarctica (boysen-ennen et al. 1991; robins et al. 1995; ward et al. 1995). the carbon flux due to migrant fauna respiration below 200-m depth (10.2 mg c m-2 day-1) represented less than 0.01% of the averaged primary production measured in the area (2854.5 mg c m-2 day-1; agawin, unpubl. data). at the time of our sampling, khim et al. (2007) were conducting a year-long study to determine carbon fluxes to depths of 960 and 1860 m in the bransfield strait. most sediment particles (60–73%) were of lithogenic origin, followed by biogenic silica (20%) and organic carbon (3–5%). the organic carbon flux was similar at 960and 1860-m depths (54.98 and 54.49 mg c m-2 day-1, respectively). the authors suggested that this carbon was first coming from the diatom spring bloom (gravitational flux), and, later in summer, from zooplankton faecal pellets (active flux). in this sense, anadón et al. (2002) observed summer carbon fluxes in the region ranging from 160 to 800 mg c m-2 day-1 at depths of 60–65 m. they calculated an average export flux from the euphotic zone of 294 � 89 mg c m-2 day-1, which represented 25.6% of the primary production (varela et al. 2002), and suggested that the bransfield strait played an important role as a carbon sink area. on the other hand, ebersbach & trull (2008) observed export fluxes due to faecal pellets to be 50–60 mg c m-2 d-1 at 100-m depth. they concluded that the majority of export flux was processed through the heterotrophic food web, and was not a direct export of phytoplankton detritus. however, if that was the case in the bransfield strait, carbon fluxes would be high during autumn and early winter, when the biomass of copepods peaks. instead, khim et al. (2007) observed that more than 99% of the carbon flux for the year occurred between december and february. the extraordinarily minimal fluxes recorded during the rest of the year suggest important carbon recycling processes in the absence of phytoplankton blooms. nevertheless, serret et al. (2001) suggested that seasonal production and respiration uncoupling in the bransfield strait would increase the role of hydrodynamics (i.e., advection) in the trophic control of carbon export. further research during the austral autumn and winter is needed to reveal the importance of microplankton, both as grazers and as prey, if we seek to assess the changes in carbon transport to the deep ocean through the year. acknowledgements we thank the crew of the rv bio hespérides, the technicians of the unidad de tecnología marina (csic) and the participants of the esepac 2000 cruise for their support at sea, especially s. agustí for inviting us to participate in the esepac project (ant97-0273). we are indebted to n. agawin for kindly supplying primary production values obtained during the cruise, and x. morán and i.a. catalán for providing additional data. this work was undertaken while l. yebra was at the biological oceanography laboratory of the universidad de las palmas de gran canaria, supported by grants from the spanish science and education ministry (mar97-1036) and the university of las palmas de gran canaria. completion of this work was funded by the european social fund (i3p programme, csic). table 2 interannual variability of mesozooplankton biomass (zpb; mg c m-2) and average primary production (pp; mg c m-2 day-1) in the bransfield strait. depth date zpb reference pp reference 0–200 12/1991 34.6* hernández-león et al. 1999 333 basterretxea & arístegui 1999 0–200 01/1993–02/1993 133.6* hernández-león et al. 2000 423–3913 basterretxea & arístegui 1999 0–200 01/1994 713–1039 alcaraz et al. 1998 684–1396 alcaraz et al. 1998 0–200 12/1995–02/1996 136–431 cabal et al. 2002 14–176 varela et al. 2002 0–43 02/1998 — — 262–889 morán et al. 2001 0–200 01/2000–02/2000 94.0–240.5 present work 578–6911 agawin unpubl. data 0–550 270.4–373.2 0–200 01/2001–02/2001 9.3–179.3* catalán et al. 2008 — — 0–250 12/2002 55 calbet et al. 2005 23–451† morán et al. 2006 *carbon calculated from dry weight (dw) applying a c : dw ratio of 0.4 for crustaceans (postel et al. 2000) and 0.05 for salps (schneider 1989). †pp estimated from surface experiments, and assuming 15 h of light per day. antarctic summer zooplankton metabolism l. yebra et al. polar research 28 2009 415–425 © 2009 the authors422 references agustí s., satta m.p. & mura m.p. 2004. summer community respiration and pelagic metabolism in upper surface antarctic waters. aquatic microbial ecology 35, 197–205. alcaraz m., saiz e., fernández j.a., trepat i., figueiras f., calbet a. & bautista b. 1998. antarctic zooplankton metabolism: carbon requirements and ammonium excretion of salps and crustacean zooplankton in the vicinity of the bransfield strait during january 1994. journal of marine systems 17, 347–359. anadón r., álvarez-marques f., fernández e., varela m., zapata m., gasol j.m. & vaque d. 2002. vertical biogenic particle flux during austral summer in the antarctic peninsula area. deep-sea research part ii 49, 883–901. arístegui j., montero m.f., ballesteros s., basterretxea g. & vanlenning k. 1996. planktonic primary production and microbial respiration measured by c-14 assimilation and dissolved oxygen changes in coastal waters of the antarctic peninsula during austral summer: implications for carbon flux studies. marine ecology progress series 132, 191–201. atkinson a. 1996. subantarctic copepods in an oceanic, low chlorophyll environment: ciliate predation, food selectivity and impact on prey populations. marine ecology progress series 130, 85–96. atkinson a. 1998. life cycle strategies of epipelagic copepods in the southern ocean. journal of marine systems 15, 289–311. atkinson a., schnack-schiel s.b., ward p. & marin v. 1997. regional differences in the life cycle of calanoides acutus (copepoda: calanoida) within the atlantic sector of the southern ocean. marine ecology progress series 150, 99–111. atkinson a. & shreeve r.s. 1995. response of the copepod community to a spring bloom in the bellingshausen sea. deep-sea research part ii 42, 1291–311. atkinson a. & snyder r. 1997. krill–copepod interactions at south georgia, antarctica, i. omnivory by euphausia superba. marine ecology progress series 160, 63–76. atkinson a., ward p., hill a., brierley a.s. & cripps g.c. 1999. krill–copepod interactions at south georgia, antarctica, ii. euphausia superba as a major control on copepod abundance. marine ecology progress series 176, 63–79. atkinson a., ward p. & murphy e.j. 1996. diel periodicity of subantarctic copepods: relationships between vertical migration, gut fullness and gut evacuation rate. journal of plankton research 18, 1387–405. båmstedt u. 2000. a new method to estimate respiration rate of biological material based on the reduction of tetrazolium violet. journal of experimental marine biology and ecology 251, 239–263. basterretxea g. & arístegui j. 1999. phytoplankton biomass and production during late austral spring (1991) and summer (1993) in the bransfield strait. polar biology 21, 11–22. bergeron j.p., alayse-danet a.m. & razouls c. 1985. metabolic adaptations of antarctic mesozooplanktonic systems to the phytoplankton standing crop in late austral summer. in j.s. gray & m.e. christiansen (eds.): marine biology of polar regions and the effect of stress on marine organisms. pp. 157–166. chichester: wiley. boysen-ennen e., hagen w., hubold g. & piatkowski u. 1991. zooplankton biomass in the ice-covered weddell sea, antarctica. marine biology 111, 227–235. cabal j.a., álvarez-marques f., acuña j.l., quevedo m., gonzalez-quiros r., huskin i., fernández d., del valle c.r. & anadón r. 2002. mesozooplankton distribution and grazing during the productive season in the northwest antarctic peninsula (fruela cruises). deep-sea research part ii 49, 869–882. calbet a., alcaraz m., atienza d., broglio e. & vaque d. 2005. zooplankton biomass distribution patterns along the western antarctic peninsula (december 2002). journal of plankton research 27, 1195–1203. catalán i.a., morales-nin b., company j.b., rotllant g., palomera i. & emelianov m. 2008. environmental influences on zooplankton and micronekton distribution in the bransfield strait and adjacent waters. polar biology 31, 691–707. conover r.j. & huntley m. 1991. copepods in ice-covered seas. distribution, adaptations to seasonally limited food, metabolism, growth pattern and life cycle strategies in polar seas. journal of marine systems 2, 1–41. drits a.v., pasternak a.f. & kosobokova k.n. 1993. feeding, metabolism and body-composition of the antarctic copepod calanus propinquus brady with special reference to its life-cycle. polar biology 13, 13–21. ebersbach f. & trull t.w. 2008. sinking particle properties from polyacrylamide gels during the kerguelen ocean and plateau compared study (keops): zooplankton control of carbon export in an area of persistent natural iron inputs in the southern ocean. limnology and oceanography 53, 212–224. froneman p.w., pakhomov e.a., perissinotto r. & mcquaid c.d. 1996. role of microplankton in the diet and daily ration of antarctic zooplankton species during austral summer. marine ecology progress series 143, 15–23. gómez m., torres s. & hernández-león s. 1996. modification of the electron transport system (ets) method for routine measurements of respiratory rates of zooplankton. south african journal of marine science 17, 15–20. graneli e., graneli w., rabbani m.m., daugbjerg n., fransz g., cuzinroudy j. & alder v.a. 1993. the influence of copepod and krill grazing on the species composition of phytoplankton communities from the scotia–weddell sea—an experimental approach. polar biology 13, 201–213. guerra c. 2006. growth rate determination in larval krill (euphausia superba dana) during antarctic autumn in the lazarev sea. a methodology comparison. master’s thesis, university of bremen. antarctic summer zooplankton metabolisml. yebra et al. polar research 28 2009 415–425 © 2009 the authors 423 hernández-león s., almeida c., portillo-hahnefeld a., gómez m. & montero i. 2000. biomass and potential feeding, respiration and growth of zooplankton in the bransfield strait (antarctic peninsula) during austral summer. polar biology 23, 679–690. hernández-león s., almeida c., portillo-hahnefeld a., gómez m., rodriguez j.m. & arístegui j. 2001. zooplankton biomass and indices of feeding and metabolism in relation to an upwelling filament off northwest africa. journal of marine research 60, 327–346. hernández-león s., almeida c., portillo-hahnefeld a., gómez m., rodriguez j.m. & arístegui j. 2002. zooplankton biomass and indices of feeding and metabolism in relation to an upwelling filament off northwest africa. journal of marine research 60, 327–346. hernández-león s. & gómez m. 1996. factors affecting the respiration/ets ratio in marine zooplankton. journal of plankton research 18, 239–255. hernández-león s. & montero i. 2006. zooplankton biomass estimated from digitalized images in antarctic waters: a calibration exercise. journal of geophysical research—oceans 111, c05s03. hernández-león s., portillo-hahnefeld a., almeida c., bécognée p. & moreno i. 2001. diel feeding behaviour of krill in the gerlache strait, antarctica. marine ecology progress series 223, 235–242. hernández-león s., torres s., gómez m., montero i. & almeida c. 1999. biomass and metabolism of zooplankton in the bransfield strait (antarctic peninsula) during austral spring. polar biology 21, 214–219. hosie g.w. 1994. the macrozooplankton communities in the prydz bay region, antarctica. in s. el-sayed (ed.): southern ocean ecology. the biomass perspective. pp. 98–123. london: cambridge university press. huntley m.e., brinton e., lopez m.d.g., townsend a. & nordhausen w. 1990. racer: fine-scale and mesoscale zooplankton studies during the spring bloom, 1989. antarctic journal of the united states 25, 157–159. ikeda t. 1985. metabolic rates of epipelagic marine zooplankton as a function of body-mass and temperature. marine biology 85, 1–11. ikeda t. & motoda s. 1978. estimated zooplankton production and their ammonia excretion in kuroshio and adjacent seas. fishery bulletin 76, 357–367. ikeda t., torres j.j., hernandez-leon s. & geiger s.p. 2000. metabolism. in r.p. harris et al. (eds.): ices zooplankton methodology manual. pp. 455–532. london: academic press. jacques g. & panouse m. 1991. biomass and composition of size fractionated phytoplankton in the weddell–scotia confluence area. polar biology 11, 315–328. khim b.k., kim d., shin h.c. & kim d.y. 2007. particle fluxes and delta n-15 variation of sinking particles in the central bransfield strait (antarctica). geosciences journal 11, 201–209. king a. & lacasella e.l. 2003. seasonal variations in abundance, diel vertical migration, and population structure of metridia gerlachei at port foster, deception island, antarctica. deep-sea research part ii 50, 1753–1763. lancraft t.m., hopkins t.l., torres j.j. & donnelly j. 1991. oceanic micronektonic macrozooplanktonic community structure and feeding in ice covered antarctic waters during the winter (ameriez 1988). polar biology 11, 157–167. lancraft t.m., relsenbichler k.r., robison b.h., hopkins t.l. & torres j.j. 2004. a krill-dominated micronekton and macrozooplankton community in croker passage, antarctica with an estimate of fish predation. deep-sea research part ii 51, 2247–2260. lancraft t.m., torres j.j. & hopkins t.l. 1989. micronekton and macrozooplankton in the open waters near antarctic ice edge zones (ameriez-1983 and ameriez-1986). polar biology 9, 225–233. lopez m.d.g. & huntley m.e. 1995. feeding and diel vertical migration cycles of metridia gerlachei (giesbrecht) in coastal waters of the antarctic peninsula. polar biology 15, 21–30. lowry p.h., rosenbrough n.j., farr a.l. & randall r.j. 1951. protein measurement with a folin phenol reagent. journal of biology and chemistry 193, 265–275. morán x.a.g., gasol j.m., pedros-alio c. & estrada m. 2001. dissolved and particulate primary production and bacterial production in offshore antarctic waters during austral summer: coupled or uncoupled? marine ecology progress series 222, 25–39. morán x.a.g., sebastian m., pedros-alio c. & estrada m. 2006. response of southern ocean phytoplankton and bacterioplankton production to short-term experimental warming. limnology and oceanography 51, 1791–1800. murray a.w.a., watkins j.l. & bone d.g. 1995. a biological acoustic survey in the marginal ice-edge zone of the bellingshausen sea. deep-sea research part ii 42, 1159–1175. omori m. & ikeda t. 1984. methods in marine zooplankton ecology. new york: john wiley and sons. packard t.t. 1971. the measurement of respiratory electron transport activity in marine phytoplankton. journal of marine research 29, 235–244. packard t.t., devol a.h. & king f.d. 1975. effect of temperature on the respiratory electron transport system in marine plankton. deep-sea research 22, 237–249. pakhomov e.a., perissinotto r. & mcquaid c.d. 1994. comparative structure of the macrozooplankton/ micronecton communities of the subtropical and antarctic polar fronts. marine ecology progress series 111, 155–169. pakhomov e.a., perissinoto r. & mcquaid c.d. 1996. prey composition and daily rations of myctophid fishes in the southern ocean. marine ecology progress series 134, 1–14. pakhomov e.a., perissinotto r., mcquaid c.d. & froneman p.w. 2000. zooplankton structure and grazing in the atlantic sector of the southern ocean in late austral summer 1993. part 1. ecological zonation. deep-sea research part i 47, 1663–1686. antarctic summer zooplankton metabolism l. yebra et al. polar research 28 2009 415–425 © 2009 the authors424 park c. & wormuth j.h. 1993. distribution of antarctic zooplankton around elephant-island during the austral summers of 1988, 1989, and 1990. polar biology 13, 215–225. pasternak a.f. & schnack-schiel s.b. 2001. feeding patterns of dominant antarctic copepods: an interplay of diapause, selectivity, and availability of food. hydrobiologia 453, 25–36. perissinotto r., gurney l. & pakhomov e.a. 2000. contribution of heterotrophic material to diet and energy budget of antarctic krill, euphausia superba. marine biology 136, 129–135. postel l., fock h. & hagen w. 2000. biomass and abundance. in r.p. harris et al. (eds.): ices zooplankton methodology manual. pp. 83–192. london: academic press. price h.j., boyd k.r. & boyd c.m. 1988. omnivorous feeding behaviour of the antarctic krill euphausia superba. marine biology 97, 67–77. robins d.b., harris r.p., bedo a.w., fernandez e., fileman t.w., harbour d.s. & head r.n. 1995. the relationship between suspended particulate material, phytoplankton and zooplankton duirng the retreat of the marginal ice zone in the bellingshausen sea. deep-sea research part ii 42, 1137–1158. rutter w.j. 1967. protein determinations in embryos. in f.h. wilt & n.k. wessels (eds.): methods in developmental biology. pp. 671–684. new york: academic press. schalk p.h. 1990. biological activity in the antarctic zooplankton community. polar biology 10, 405–411. schnack-schiel s.b. & hagen w. 1994. life cycle strategies and seasonal variations in distribution and population structure of four dominant calanoid copepod species in the eastern weddell sea, antarctica. journal of plankton research 16, 1543–1566. schnack-schiel s.b. & hagen w. 1995. life-cycle strategies of calanoides acutus, calanus propinquus, and metridia gerlachei (copepoda: calanoida) in the eastern weddell sea, antarctica. ices journal of marine science 52, 541–548. schnack-schiel s.b. & mújica a. 1994. the zooplankton of the antarctic peninsula region. in s.z. el-sayed (ed.): southern ocean ecology. the biomass perspective. pp. 79–92. london: cambridge university press. schneider g. 1989. carbon and nitrogen content of marine zooplankton dry material: a short review. plankton newsletter 12, 41–44. serret p., fernández e., anadón r. & varela m. 2001. journal of plankton research 23, 1345–1360. sturz a.a., gray s.c., dykes k., king a. & radtke j. 2003. seasonal changes of dissolved nutrients within and around port foster deception island, antarctica. deep-sea research part ii 50, 1685–1705. tucker m.j. & burton h.r. 1990. seasonal and spatial variations in the zooplankton community of an eastern antarctic coastal location. polar biology 10, 571–579. varela m., fernandez e. & serret p. 2002. size-fractionated phytoplankton biomass and primary production in the gerlache and south bransfield straits (antarctic peninsula) in austral summer 1995–1996. deep-sea research part ii 49, 749–768. voronina n.m., kosobokova k.n. & pakhomov e.a. 1994. composition and biomass of summer metazoan plankton in the 0–200 m layer of the atlantic sector of the antarctic. polar biology 14, 91–95. ward p., atkinson a., murray a.w.a., wood a.g., williams r. & poulet s.a. 1995. the summer zoplankton community at south georgia: biomass, vertical migration and grazing. polar biology 15, 195–208. ward p., atkinson a., schnack-schiel s.b. & murray a.w.a. 1997. regional variation in the life cycle of rhincalanus gigas (copepoda: calanoida) in the atlantic sector of the southern ocean—re-examination of existing data (1928 to 1993). marine ecology progress series 157, 261–275. ward p., grant s., brandon m., siegel v., sushin v., loeb v. & griffiths h. 2004. mesozooplankton community structure in the scotia sea during the ccamlr 2000 survey: january–february 2000. deep-sea research part ii 51, 1351–1367. weeks a.r., griffiths g., roe h., moore g., robinson i.s., atkinson a. & shreeve r. 1995. the distribution of acoustic backscatter from zooplankton compared with physical structure, phytoplankton and radiance during the spring bloom in the bellinghausen sea. deep-sea research part ii 42, 997–1019. wickham s.a. & berninger u.g. 2007. krill larvae, copepods and the microbial food web: interactions during the antarctic fall. aquatic microbial ecology 46, 1–13. yebra l., almeida c. & hernández-león s. 2005. vertical distribution of zooplankton and active flux across an anticyclonic eddy in the canary island waters. deep-sea research part i 52, 69–83. yebra l., harris r.p. & smith t. 2005. comparison of five methods for estimating growth of calanus helgolandicus later developmental stages (cv-cvi). marine biology 147, 1367–1375. yebra l. & hernández-león s. 2004. aminoacyl-trna synthetases activity as a growth index in zooplankton. journal of plankton research 26, 351–356. yebra l., hirst a.g. & hernández-león s. 2006. assessment of calanus finmarchicus growth and dormancy using the aminoacyl-trna synthetases method. journal of plankton research 28, 1191–1198. zhou m., niller p.p., zhu y.w. & dorland r.d. 2006. the western boundary current in the bransfield strait, antarctica. deep-sea research part i 53, 1244–1252. zhou m., nordhausen w. & huntley m. 1994. adcp measurements of the distribution and abundance of euphausiids near the antarctic peninsula in winter. deep-sea research part i 41, 1425–1445. antarctic summer zooplankton metabolisml. yebra et al. polar research 28 2009 415–425 © 2009 the authors 425 the distribution and abundance of seabirds off southwestern greenland in autumn and winter 1988-1989 jan durinck and k n u d falk durinck, j.& falk, k . 1996: the distribution and abundance of seabirds o f f southwestern greenland in autumn and winter 1988-1989. polur reseurch zs(z), 23-42. ship-based surveys of seabirds were carried out off southwestern greenland in the autumn of 1988 and winter of 1989. the results provide the first quantitative information on seabird distribution and numbers for single seasons and estimates for one particular area in winter. some oceanographic habitat characteristics important for seabird distribution arc described. in winter, high numbers of king eiders somaferiuspecrabilis, brunnich’s guillemots urialomuiu, glaucous gulls lorushyperboreus. iceland gulls lurusgluucoides, great black-hackcd gulls lururmurinus and black guillemots cepphusgrylle were found in offshore habitats with heavy ice cover. a n estimated 280,000 king eiders, 170,000 brunnich’s guillemots, 2,500 glaucous gulls, 7,000 iceland gulls, 9,500 great black-backed gulls and 25,000 black guillemots were found in winter in an area west of nuuk. jan durinck, o r n b consuii ltd., bygmurken 42, dk-7730 hansihoim. denmark. knurl f d k , ornis consult l t d . , vesterbrogude 140a, 3., dk-1620 copenhagen v , denmark. introduction greenland has always relied heavily on marine resources. through the last decades stock assess ments and surveys of distribution of the most economically important species of fish, invert ebrates and marine mammals have been impor tant tools for resource management. although heavily exploited, seabirds have not been included i n routine monitoring programs, but the work of several scientists has led to the mapping of the breeding distribution of most colonial species in western greenland, and to estimates of population size and change (salomonsen 1950, 1979; joensen & preuss 1972; boertmann 1979; evans 1984; kampp 1990; evans & kampp 1991; boertmann 1994; kampp et al. 1994). seabird breeding colonies are relatively easy to map and census, but determining the distribution of marine birds at sea is costly and much more labourous. relatively few studies of the dis tribution of seabirds have been conducted near greenland, particularly in fall and winter. with increasing human resource exploitation in marine areas, man-induced impacts on seabird popu lations have become evident. the first clear example of human interactions with seabirds from greenland waters was the huge bycatch of seabirds, especially briinnich’s guillemots uri alomvia, in salmon drift nets set off west greenland in the early 1970s (tull et al. 1972; christensen & lear 1977). pollution from oil exploration and transportation presents a more general risk to seabirds. as there is a clear need to minimize these risks, information o n seabird distribution at sea is now in high demand, especially in the area off western greenland where there is renewed interest in oil exploration. the distribution of seabirds in greenland waters outside the breeding season has been described in general terms by salomonsen (1950). in recent years quantitative information been collated as part of a seabird mapping program for eastern canada with the rough mapping of seabird distribution in greenland waters based on surveys from research vessels. the results of these surveys combined with efforts from various years were published as a seabird atlas by brown et al. (1975) and subsequently updated by brown (1986). the latter presents maps based on obser vations from the period 31 march 1969 to 31 december 1983. other programs that mapped seabirds in the waters between canada and greenland were carried out by canadian biol ogists from aircraft (mclaren 1982; mclaren & renaud 1982; renaud et al. 1982). evans & waterston (1976) presented the results of counts of briinnich’s guillemots in august and 24 j . durinck & k . falk early september from passenger vessels in coastal waters of west greenland. boertmann (1979) mentioned scattered observations from disko bay southwards during the summers 1975 and 1976. seabird distribution in autumn was in directly studied by christensen & lear (1977) while researching bycatch in salmon drift nets. this paper presents the first available information on distribution and numbers of seabirds in south western greenland waters through the autumn and winter. study area the surveys were mainly conducted in waters less than 500 m deep along southwestern greenland. the surface waters off the coast are dominated by cold water derived from the polar current, which transports water from the polar basin south along the east greenland coast and around cape farewell to the west coast of greenland (buch 1990). atlantic water is transported around cape farewell alongside the polar current. as these currents move north along the west coast of greenland, they mix and gradually turn west towards labrador and baffin island. satellite images indicated that all transects fell within the polar current except for the westernmost tran sects off sisimiut; the limit of the polar current is indicated in fig. 1a. strong northerly winds along west greenland may cause upwellings near the coast due to ekman transport of surface water away from the coast (buch 1990). satellite images revealed that such upwellings occurred at least twice within the study area during the early autumn survey. the first event was in late august just south of cape thorwaldsen, and in early october upwellings were observed in the area between nuuk and maniitsoq as well as just south of nuuk fiord (fig. 1a). fig. i. shipbased line transects off southwestern greenland: (a) 29 august 3 october 1988; (b) 23 october-25 november 1988: (c) 14 february-15 march 1989. the distribution and abundance of seabirds off southwestern greenland 1988-1 989 25 methods and material data were collected by the authors during three surveys. survey 1 spanned the period 29 august 3 october 1988, and covered the west greenland coast between approximately 60”n and 72”n (fig. 1a). this survey comprised 2,300 km transect lines, with a total of 736 10-minute sample periods. survey 2 included observations per formed between 23 october and 25 november 1988 along the coast from maniitsoq and nanor talik (550 km, 167 10-minute periods). a signifi cant part of the survey took place in inshore waters (between islands and skerries) just north of nanortalik (fig. 1b). survey 3 took place from 14 february to 5 march, when surveys were slowed by dense ice cover (1,10okm, 414 10 minute periods). most of the time was spent in the northernmost navigable waters just west of nuuk fjord. an area of about 6,000km2 was covered with a high density of transect lines, allowing estimates of numbers of birds within that area (fig. 2). within this single area, a total of 230 10-minute bird counts were made, and 645 km transect lines were sailed which equals a coverage of 196 km2 (3.4% of the total area). all obser vations were carried out from fisheries inspection vessels and passenger vessels. international observation standards were used which include a “snapshot technique” to allow for flux of birds in flight (tasker et al. 1984; webb & durinck 1992). bird observations were recorded in 10-minute periods and noted on field sheets for subsequent database storage. each seabird observation was assigned one of three transect “bands”: (1) from the ship t o 150 m , (2) between 15c a and 300 m fig. 2. area southwest of nuuk, greenland with intensive sampling in fehruary and march 1089. from the ship, o r (3) further away than 300m. only observations within 300 m have been used to calculate relative densities (birds/km*). density was calculated as a 20-minute mean (two 10 minute periods) without compensation for changes in detectability over distance for different species (skov et al. 1995). within the 300 m tran sect, most birds were identified to species but some alcids and phalaropes could not be ident ified. not including little auk alle alle, brunnich’s guillemots made up 97% of all alcids identified to species (table 1) and therefore unidentified large alcids have been treated as briinnich’s guillemots in further analyses. likewise, red-necked phala ropes phalaropus lobatus made up 98% of all phalaropes identified to species; observations of phalaropus sp. have therefore been treated as p . lobatus. observations were only carried out in good or fair weather conditions, i.e. wind speed below lom/s and visibility greater than 500m. birds following trawlers or other ships were excluded from density calculations. colour phases on ful mars fulmarus glacialis were recorded according to franeker & wattel (1982). sea surface temperatures (“c) were recorded in a total of 513 10-minute periods from ther mometers monitoring the temperature of the cooling water for engines of the fisheries inspec tion vessels. a utilization test was used to indi cate whether the numbers of a given species found in a given range. of temperature differed sig nificantly (95% confidence limit chosen) from that expected from the distribution of effort (haney & solow 1992). in these 513 10-minute periods seven species of seabirds were considered numerous enough to allow this test (fig. 16). observation of ice cover in tenths (where 0/10 means no ice in sight and 10/10 is total ice cover) was sampled in 368 10-minute periods. nine sea bird species were considered numerous enough to allow a utilization test to determine if waters with certain ranges of ice cover supported some birds more than others (fig. 17). a total of about 4,000 km (2,200 nautical miles) of transects were sailed, yielding a total sample of 1,317 10-minute periods of observation. most transects fell within 50 km of the coast, although some transects in september were as far as 200 km offshore (fig. 1). except for the surveys off nuuk in february 1989 (fig. 2), transect coverage was not dense enough to estimate population sizes of birds within the sampled areas. 26 j . durinck & k . fulk table 1. bird species observed during three surveys off southwestern greenland 1988/1989 species red-throated diver gavia stellata great northern diver gavia immer fulmar fulmarus glacialis great shearwater pujjinus grauk great cormorant phalacrocorax curbo canada goose branta canadensis mallard anus platyrhynchos king eider somateria spectabilis common eider somateria mollissima eider sp. somateria spp. harlequin duck histrionicus histrionicus long-tailed duck clangula hyemalis duck sp. anus sp. red-breasted merganser mergus scrrutur white-tailed eagle haliaetus albicilla gyrfalcon faicu rwricolus sanderling culidris alba knot culidris canutus dunlin culidris alpina purple sandpiper calidris rnaritima sandpiper sp. calidris spp. rcd-necked phalarope phalaropus lobatus grey phalarope phaluropus fulicarius phalarope bp. phufuropus spp. great skua stercorarius skua pomarinc hkua stercorarius pomarinus arctic skua stercorarius parasiticus kittiwake rissa tridactyla ivory gull pagophila eburnea sabines' gull larus sabinr herring gull larus argentatus glaucous gull larus hyperboreus iceland gull larus g1aucoide.i great black-hacked gull l a r u marinas gull sp. lurus spp. arctic tern sterna paradisaeu guillcmot uriu aolge briinnich's guillemot uria lomuia razorhill a k a tordu black guillemot cepphus grylle puffin fratercula arctica little auk alle alle alcid sp. uriu spp. raven coruus curax surveys 3' 31 2 7,661 1,971 2 42 16 62 225 208 1 20 36 17 2 403 5 22 296 112 135 3 1 3 1,792 40 7,482 826 5,356 384 4 4 11 19 25 2 224 1 4 167 9 1 52 2 3 2 23,042 150 i1 2 5 1 1,681 125 146 68 63 285 41 1 206 1,234 3,255 52 746 197 13 2 3,324 11,875 15,264 77 418 427 47 27 867 264 198 2,467 7 71,96 1 87 1 sum 31 2 9,856 1,971 47 42 16 7,566 1,347 5,676 1 539 43 18 2 7 1 1 i 19 7 27 225 4 i67 9 1 52 23,203 2 5 1 1,952 416 1,x51 4,053 197 15 30,463 i 922 74 1.329 73,760 88 ~~ 29 auguat-3 october 1988 23 octobcr-2 november 1988 14 february-5 march 1989 on the early autumn survey. relative abundance and distribution changed considerably between the three survey periods. as t h e winter of 1988-89 was colder and more severe than usual in west greenland, most fjords became ice covered and waters north of nuuk results a total of 38 bird species were recorded o n the three surveys (table 1 ) . overall, t h e briinnich's guillemot was the most abundant, although kitti wakes rissatridactyla outnumbered all other birds t h e distribution and abundance of seabirds ofy southwestern greenlurid 1988-1989 27 were almost completely ice covered by mid feb ruary. the survey carried out in february in some of the northernmost open waters revealed that there were huge concentrations of alcids and eider ducks (figs. 5c, 6c, 13c and 14c) among the ice floes and near the ice edge. in late february 1989, an area of about 6,000 km2 (fig. 2) held an estimated 500,000 birds, mainly king eiders and briinnich’s guillemots. species account red-throated diver guuia stelluta red-throated divers were only observed during survey 1, during the period 29 august -11 sep tember 1988. fulmar fulmarus glacialis the fulmar was the most widespread and the secondmost numerous bird seen during survey 1 (table 1). fulmars were observed in all areas except for fjords, waters close to the coast and parts of disko bay (fig. 3). the highest densities were found on survey 1 ca. 25 km offshore south of aasiaat and south of paamiut. fulmar densities tended to decrease with increasing distance from land. the average density of fulmars during sur vey 1 was 5.sbirds/km2 (n = 780 10min. periods). an average density of 8.0 birds/km2 (n = 146) was calculated for the area just south of paamiut and 6.6 birds/km2 (n = 104) for the area between nuuk and manitsoq. the areas with fulmar concentrations coincided in space and time with observed upwelling areas. during survey 1 the area just south of aasiaat had the highest average density of fulmars (12.6 birds/km2 n = 100). in late september, only a few fulmars were fig. 3 . distribution of fulmar fulmarusghcialis off southwestern greenland. 28 j . durinck & k . falk observed north of aasiaat. fulmar numbers were low in areas characterised by low sea-surface tem peratures, whereas numbers were high in the warmest water masses (fig. 16). concentrations of fulmars were often observed near long lines of drifting material, and this was the dominant species attending working fish trawlers. on survey 1,13% of all fulmars were observed near trawlers. fulmars were less abundant on survey 2, and none were observed south of paamiut (fig. 3b). transects in the southernmost area, however, were performed in inshore waters between islands and skerries wherefulmars are rarely found. north of paamiut, the average density of fulmars was 4.1 birds/km2 (n = 76). o n survey 3, fulmars were not seen in waters with any but the lightest ice cover (fig. 17) and were only seen in and around an open water area between paamiut and nuuk, where high densities were recorded. the proportion of birds recorded in primary moult decreased during september from 48% (n = 141) o n 4 september to 24% (n = 169) on 16 september and to 19% (n = 291) on 27 sep tember. primary moult was not observed during surveys 2 and 3. the composition of colour phases in mid-september between sisimiut and cape thorwaldsen was 60% ll, 6% l, 17% d and 17% dd (n = 660). the highest proportions of dark birds were found around nuuk. during sur vey 2 , the proportion of light phase birds (ll) was 92% (n = 167), and during winter 62% (n = 58). great shearwater puflnus gravis during survey 1, the great shearwater was the fourth most numerous species observed (table 1). nearly all the great shearwaters (97%) were seen in the last three days of august. the last individual was seen off nuuk on 11 september. shearwaters were roughly distributed in two large aggregations (fig. 4); one just north of nuuk had an average density of 2.6 birds/km2, (n = 62) and one covering a large area around cape thor waldsen had an average density of 6.3 birds/km2 (n = 114). the northernmost observation of great shearwaters was made at 67"13'n on 10 septem ber. great shearwaters were not recorded in the coldest water masses and most were observed in areas within the middle or high ranges of tem perature (fig. 16). the upwelling areas south of nuuk and cape thorwaldsen coincided with the two centers of great shearwater distribution. no great shearwaters were seen attending trawlers. king eider somateria spectabilis the only flocks of king eiders recorded in sep tember were in northern disko bay (fig. 5a). our survey of disko bay was not thorough and we did not record the large moulting flocks which gather there during summer and autumn (sal omonsen 1950). birds were seen during survey 2 around paamiut (fig. 5b) in low densities (0.3 birds/km2, n = 74). i0 2 0 1 \ "2 i 6 4 2 s u r v e y 1 october 3 puff inus gravis 100 72 70 6e 66 64 n a n o r t a l i k fig. 4 . distribution of great shearwater puflinusgraois off south western greenland. t h e distribution and abundance of seabirds off southwestern greenland 1988-1989 29 f i g . 5. distribution of king eider somazeriaspectabilis o f f southwestern greenland. on survey 3, high densities of king eiders were observed west of nuuk and in the almost ice free nuuk fjord. large flocks of king eiders regularly gather in the ice free waters of nuuk fjord (local hunters pers. comm.). however, on our survey most birds resided in areas with heavy drift ice and scattered openings in the ice southwest of nuuk fjord. king eiders were significantly associ ated with high ice cover (fig. 17). king eiders were not found throughout the 6,000 km2 area west of nuuk, but the average density of eiders was 54.3 birds/km2 (n = 2 2 6 ) , and the population within that area may be estimated t o about 280.000 birds. common eider somateria rnollissima common eiders were the most frequently seen of the two eider species during both surveys 1 and 2 , but were outnumbered by king eiders (85%) on survey 3. however, few were seen at any time and most were not identified to species. most of the few birds observed on survey 1 were seen between aasiaat and sisimiut (fig. 6a) and the density of common eiders calculated for this region was (0.9 birds/km*, n = 98, fig. 6a). during survey 2, most eiders were recorded near the coast around paamiut (fig. 6b), and the density on this line was 2.2 birds/km* (n = 74). during survey 3 all eiders observed were con centrated among the ice in the archipelago west of nuuk (fig. 6c). common eiders were present in most icefree parts of nuuk fjord. generally, common eiders were not associated with heavily ice-covered areas (fig. 17). an average density of 7 . 6 birds/km2 (n = 84) was found in a 1,500 km2 area west of nuuk, which leads to an estimate of ca. 12,000 common eiders occupying this area during survey 3 . 30 j . duririck & k . falk somaterla molllsslmo 50 2u0 km f e b r u a r y 14 fig. 6. distribution crf common eider somateria molli.s.sima off southwestern i greenland. long-tailed duck clangula hyrninlis a few long-tailed ducks were seen in on survey 1, (fig. 7a). on survey 2, long-tailed ducks were relatively common near nanortalik (fig. 7b). the long-tailed duck density in this area was 1.1 birds/ km? (n = 66). long-tailed ducks were con centrated in t h e icy waters near nuuk in winter (fig. 7c). gyrfalcon falco rusticolus n o gyrfalcons were seen at sea during surveys 1 and 2. during winter gyrfalcons were seen up to 50 kilometres offshore in bird rich areas, and on some occasions the falcons were obviously hunting seabirds in areas with plenty of king eiders and briinnich’s guillemots. five birds observed at close range were light grey o r white. red-necked phalarope phalaropus lobatus this species was only recorded during survey 1. and the last birds were seen o n 30 september 1988. t h e average density of phalaropes on survey 1 was 0.47 birds/km2 (n = 780). red-necked phalaropes were seen along most of the coast and densities generally decreased with increased distance from shore (fig. 8). most phalaropes were seen south of n u u k , associated with con centrations of fulmars and guillemots. many large baleen whales were also present in the area. the average density of phalaropes in that area was 4.2 birds/km’ (n = 44). t h e phalaropes were found associated with waters with a temperature range between 0.5 and 1.5c (fig. 16). grey phalarope phalaropus fulicarius only four grey phalaropes were observed, all at the distribution arid abundance of seabirds off soicthwestern greenland 1988-1989 3 i fig. 7. distribution o f long tailed duck clangulahyeinalis o f f southwestern greenland. nenortali k , 2 b i r d r l k m ' 1 5 5 50 least 50 k m offshore; two birds were seen south of paamiut o n 31 august, o n e west of nuuk o n 15 september and the o t h e r northwest of paamiut o n 30 september. kittiwake rissa tridactylu kittiwakes were t h e most numerous species observed during survey 1. they were present almost everywhere, although very few were rec orded close to t h e coast, between islands and skerries, in t h e disko bay and in the area just north of nanortalik (fig. 9 a ) . numbers gradually declined during september, but a few still remained in late autumn and winter (fig. 9b and c). in autumn, kittiwakes a r e known to occur regularly in flocks along t h e coast (pihl 1076) o r in offshore areas (salomonsen 1979; brown 1986). o n survey 1, the distribution of t h e kit r 50' 4d october 2 3 november 2 1 3 m a n i i t s o q october 2 3 november 2 s u r v e y 3 march 5 tiwakes seemed t o b e associated with the warmer waters within t h e surveyed area (fig. 16). t h e average density for the total area covered in survey 1 was 7.9 birds/km2 (n = 780). a n aver age density of 11.5 birds/km2 (n = 140) was cal culated for t h e area around cape thorwaldsen, and 10.3 birds/km? (n = 170) for t h e area between nuuk and manitsoq. between sisimiut and aas iaat a n average density of 24.4 birds/km' (n = 104) was calculated. during survey 2 the kittiwakes appeared to have a definite northerly distribution, although this pattern may be exaggerated by the inshore placement of t h e transects in t h e southern areas during this survey. t h e average density in the northern area was 3.5 birds/km? (n = 36). only 2.8% of all kittiwake observations o n the surveys were associated with trawlers. flocks, sometimes numbering hundreds of birds, were often seen resting on icebergs. 32 j . durinck & k . falk \ \ 200 km p 100 n a n o r t a l i k \ birdslk fig. 8. distribution of red-necked phalarope phafaropuslobatlcr off southwestern greenland. glaucous gull larus hyperboreus during survey 1, the glaucous gull was the most widespread large gull. a n average of 0.14 birds/ km2 ( n = 780) was calculated for the entire survey. although the majority of glaucous gulls were seen near the coast, many birds ventured far offshore, a n d some were observed as far as 180 km offshore (fig. 10a). o n survey 2, glaucous gulls were seen in all areas surveyed (fig. lob), but most abundantly in the area around nanor talik (1.3 birds/km*, n = 66). in winter a n average density of 0.4 birds/km2 (n = 234) was found in a n area of 6,000 km2, giving a n estimate of about 2,500 glaucous gulls west of nuuk. most birds were observed in areas with moderate ice cover and this association was statistically significant (fig. 17). about 9% of all observations were associated with trawlers. iceland gull larus glaucoides t h e distribution of iceland gulls was strictly coastal in autumn (fig. l i a ) , and the highest densities were recorded on the transects close t o the shore north of nanortalik o n survey 2 (fig. 11b). t h e average density for iceland gulls o n survey 1 was calculated t o 0.08 birds/km’ (n = 780). o n survey 2 the iceland gulls were most abundant around nanortalik (0.8 birds/km*, n = 66, fig. 11b). in winter the distribution of iceland gulls shifted seaward (fig. 11c). t h e gulls were most numerous in areas with moderate ice cover (fig. 17) west of nuuk fjord and off paamiut. in the area west of nuuk a n average density of 1.2 birds/km2 (n = 296) was calculated for an area of 6,000 km2, giving an estimated population of about 7,000 iceland gulls. only a few iceland gulls were observed near fishing trawlers; in the autumn surveys n o birds were associated with trawlers, and in winter only 5 % of the obser vations were seen near operating vessels. n o birds of the subspecies l.g. kumlieni were observed on the surveys. great black-backed gull larus inarinus during surveys 1 and 2, great black-backed gulls were only seen close to the coast (fig. 12a and b). in survey 1, the average density of great black backed gulls was 0.28 birds/km2 (n = 780). only 6 % of all observations were associated with traw lers. o n survey 2. the great black-backed gulls were most abundant around nanortalik (1.5 birds/km2, n = 66. fig. 12b). in winter, great black-backed gulls were vir tually omnipresent, and high concentrations were present west of nuuk fjord (fig. 12c), in the same general area as the concentrations of king eiders, brunnich’s guillemots and black guille mots. most birds were found in areas with mod erate o r high ice cover and they seemed to avoid areas with lesser ice cover (fig. 17). in winter, only 1.4% of all observations were associated with trawlers. in an area of 6,000 km2 west of nuuk, a n average of 1.6 birds/km2 (n = 298) was the distribution and abundance of seabirds off southwestern greenland 1988-1989 33 fig. 9 . distribution of kittiwake rissatridacfyla off southwestern greenland. found, giving an estimate of about 9,500 great black-backed gulls. arctic tern sterna paradisaea terns were only recorded during the survey 1, and the last bird was seen on 10 september. briinnich's guillemot uria lomvia both guillemot species were recorded on the sur veys, although the guillemot uria aalge is not common in greenland waters, and only 15 birds were identified. briinnich's guillemots were present on most transects during all three surveys (fig. 13), being the most numerous bird in most areas, although only small numbers were observed between sisimiut and aasiaat and far from land off sisimiut (fig. 13a). in survey 1, the highest densities were generally found at dis tances of 10 to 75 kilometres offshore. the aver october 23 november 25 rlsso trldactylo s u r v e y 3 february 14 march 5 pc rissa trldoctvla c; age density of guillemots was 5.4 birds/km2 (n = 780), and in the high density area south of nuuk, the average density was 30.1 birds/km2 (n = 70). o n the transects between nuuk and sisimiut the average density was 7.6 birds/km2 (n = 226). during survey 1, most birds were recorded in waters with surface temperatures in the lower range, a picture which strikingly resembles that of the red-necked phalarope (fig. 16). in late autumn and winter the guillemots were found close t o the coast (figs. 13b and c). in survey 2, very high densities of guillemots were found along the coast and, locally, in the archi pelago northwest of nanortalik (fig. 13b). the average density of guillemots was 49.9 birds/km2 (n = 166) and the highest densities were found on the line between nuuk and cape thonvaldsen (82.5 birds/km*, n = 74). the briinnich's guillemot was the most com mon and widespread species seen on the winter survey and huge numbers of guillemots had 34 j . durinck & k . falk 5 n a n o r t a l i \ lorus lyperbreus f e b r u a r y 14 march 5 m , pc % lorus lyperboreus gathered in the waters west of nuuk. the guille mots sometimes formed very large and dense flocks; two flocks of 33,000 and 27,000 birds were counted, but the transects did not cut into these flocks. the average density of brunnich’s guille mots was 28.1 birds/km2 (n = 288) in an area of 6,000 km2, in and around the nuuk fjord, giving a total estimate of about 170,000 guillemots. in the southern part of the winter survey, an average density of 7.8 birds/km2 was found. in winter, about 30% of all guillemots were seen in small open areas within heavy drift ice, but most were found in areas with less ice cover (fig. 17). razorbill a k a tordu although the razorbill breeds in small numbers along the coast north of cape thorwaldsen (gm & o c 1993), only one bird was identified on the fig. 10. distribution of glaucous gull larlcshyperboreus off southwestern greenland. surveys. this species has probably been over looked among all the guillemots due to problems in identifying the alcids, especially the juveniles, at a distance. the species do occur in west green land in winter. we observed one juvenile during a trip with local hunters in the archipelago west off nuuk in february 1989. black guillemot cepphus grylle black guillemots were almost exclusively seen close to land during surveys 1 and 2 (fig. 14a and b). during survey 2 , the majority of black guillemots were recorded inshore northwest of nanortalik where the density was 5.1 birds/km2 (n = 66) near a large breeding colony (gm & oc 1993). during survey 3, many birds were seen offshore, and particularly large numbers were concentrated west of nuuk in the same general t h e distribution and abundance of seabirds off southwestern greenland 1988-1989 35 fig. 11. distribution of iceland gull larusgluucoides off southwestern greenland. area as guillemots and eiders (fig 14c). the average density of black guillemots in a 6,000 km2 area west of nuuk was 3.9 birds/km2 (n = 290), and the population within that area can be esti mated to about 25,000 birds. most black guille mots were found in areas with heavy ice cover (fig. 17). puffin fratercula arctica very few puffins were seen. a total of 42 obser vations comprising 47 birds were made during survey i, most birds being seen in the southern part of the area covered, especially in the area between paamiut and nanortalik. the average density of puffins in survey 1 was 0.06 birds/km2 (n = 780), but south of cape thorwaldsen the density was 0.5 birds/km2 (n = 56). on survey 2 puffins were not seen on the southern transect close to the coast. the density calculated for the northernmost line was 0.3 birds/km2 (n = 36) and for the area off paamiut, 0.2 birds/km2 (n = 74). no puffins were noted on the winter survey. little auk alle alle little auks were recorded during all three surveys. on survey 1 the highest densities (5.6 birds/km2, n = 94) were found far offshore between sisimiut and aasiaat, whereas no birds were recorded on the transect close to the coast on the same lati tudes (fig. 15a). the density south of cape thor waldsen was 1.3birds/km2 (n = 48) and the average density of little auks was 0.9 birds/km2 ( n = 780). the little auks generally were not found in waters with surface temperatures in the higher range (fig. 16). on survey 2 they were most numerous around paamiut. and none were 36 .i. durinck & k . falk recorded between islands and skerries (fig. 15b). on survey 2 the distribution of little auks resem bled that of the puffin. the density calculated for the northern line on survey 2 was 1.3 birds/km2 (n = 36) and for the area off paamiut 2.7 birds/ km2 (n = 74). during the winter survey, little auks were generally scattered in low densities (1.2 birds/km2, n = 252) in an area of 6,000 km2 west of nuuk fiord, giving an estimated 6,000 little auks for that area (fig. 15c). the densities recorded further south were very low. few little auks were found in areas with heavy ice cover (fig. 17). discussion the results of the surveys in 1988-89 confirm most existing knowledge on the general distribution and phenology of seabirds along the coast of fig. 12. distribution of great black-backed gull larusmarinus off southwestern greenland. southwestern greenland in the autumn and winter seasons (salomonsen 1950, 1979; brown 1986). in addition this study quantifies infor mation on bird numbers and distribution patterns and describes some oceanographic habitat charac teristics important for seabird distribution. the survey lines were few and scattered and only a rough picture of seabird distribution as well as indications of densities could be produced. general seabird densities were much greater close to land and over shallow areas than over the deeper parts of the study area. in some cases, seabird concentrations seemed to be related to oceanographic features such as areas with upwel lings or convergent fronts, the latter phenomena evidenced by lines of drifting matter. the fulmar was one of the most widespread and common seabirds seen along southwestern greenland. although the data do not warrant a population estimate, we believe that in autumn there were the distribution and abundance of seabirds off southwestern greenland 1988-1989 37 fig. 13. distribution of briinnich’s guillemot urialomoia off southwestern greenland at least one million fulmars in the area. the fact that only small numbers of fulmars were observed near fishing vessels indicates that fishing activities played only a minor role for the distribution of fulmars at this time of year, as found by brown (1970). the fact that fulmars were mainly found in the warmer waters found during survey 1 prob ably explains the virtual absence of fulmars from the disko bay area where sea surface tem peratures were very low. the highest proportions of dark phase birds were found around nuuk as also noted by salomonsen (1965) and boertmann (1979). presumably these birds originated from the huge breeding colonies at baffin island as is also suggested by brown et al. (1975). the numbers of great shearwaters off west greenland seems t o fluctuate from year to year; although they were numerous in the autumn of 1988, they were not observed on transect lines south of cape thorwaldsen in the summer 1990 (glahder 1993), and they were almost absent from west greenland waters in early autumn 1992 (greenland environmental research insti tute unpubl. data). a study of seabird distribution in the north atlantic suggests that the great shear waters concentrate in the waters of the irminger basin southeast of greenland (skov et al. 1994). glahder (1993) showed that high densities of great shearwaters were present off southeastern green land in august 1990. in the present study great shearwaters were found in waters within the upper range of surface temperatures measured. it has been suggested that the movements of great shearwaters around the atlantic ocean follow seasonal peaks in local food sources (brown et al. 1981). the three large gulls showed roughly similar distribution patterns. the great black-backed gull was the most numerous staying near the coast in autumn as observed by salomonsen (1950). all 38 j . durinck & k. falk 2 3 i \ 34 6 i three gull species showed higher densities close to the coast. the iceland gull was the least numerous and the species distributed closest to the coast. all three species were apparently more abundant offshore during winter. briinnich’s guillemots were the most numerous birds in this study, especially at some distance from the coast. information from seabird bycatch in salmon drift-nets in the 1970s suggests a similar distribution of guillemots in september, when the largest catch numbers (per unit effort) were recorded in relatively shallow areas a good dis tance from the coast (christensen & lear 1977). however, in late summer and autumn, guillemots can be found in small numbers everywhere in the davis strait (brown 1986). although our surveys cannot determine an accurate population estimate, the numbers in autumn were probably between half and three-quarters of a million birds off southwestern greenland. the briinnichs fig. 14. distribution of black guillemot cepphusgryue off southwestern greenland. guillemot’s affinity to the shallow offshore areas in early autumn may be the main reason that net entanglement in drift-nets is no longer a major mortality factor. currently, most nets are set in the fjords, and september is the main fishing period (falk & durinck 1991). but when the guillemots enter the fjords in late autumn the birds are exposed to hunting pressures (falk & durinck 1992). early in the autumn some little auks probably move down towards the central coast of south western greenland from the huge colonies in northwest greenland. most birds recorded in the northern part of the surveyed area in survey 1 probably derived from these colonies. the largest concentrations of little auks recorded in sep tember were found along the edge of the polar front west of sisimut (figs. 1a and 15a), implying that little auks may be found in greater numbers west of the study area. this pattern is the distribution and abundance of seabirds off southwestern greenland 1988-1989 39 fig. is. distribution of little auk allealle off southwestern greenland. 70 60 50 200 km 6 4 55 50 45 as also suggested by net-entanglement data from 1970s (christensen & lear 1977), and from sur veys in the davis strait (brown 1986). although little auks from svalbard are known t o winter off west greenland (17 ring recoveries, gm & oc 1993), and we find it surprising how few birds were recorded in the late autumn and winter surveys. in the winter of 1988-89, in the northernmost areas with some open water (nuuk fjord and the coastal area west of nuuk), huge numbers of king eiders (ca. 280,000), briinnich’s guillemots (ca. 170,000) and black guillemots (ca. 25,000) were concentrated in an area of about 6,000 km2. if this is a recurring phenomenon, the area must be regarded as an important wintering area for seabirds. the area west of nuuk is a traditional hunting area for the local inhabitants and a well known feeding area for guillemots and eider ducks (anon 1976; falk & durinck 1993). birds/ki 6 4’ october 23 november 25 alle alle f e b r u a r y 14 m a r c h 5 alle alle winter ice cover provided opportunities for land birds t o forage at sea. for predators, ice was a convenient perch for hunting and eating prey, and on several occasions gyrfalcons were seen hunting seabirds in icy areas far from land. furthermore, great black-backed gulls and ravens corms corax seemed attracted to the dense ice cover. this could be because offal was often left on the ice from trawlers operating in winter in areas with dense ice cover, thereby providing easily accessible forage to scavenging gulls and ravens. in addition, as one of the most abundant marine scavengers, the fulmar, appeared to avoid dense ice cover, the ravens and gulls had little competition in the icy waters. acknowledgements. -we wish to thank the greenland environ ment rescarch institute for funding the analysis of seabird distribution and for the use of unpublished data. the present data were collected within the project “a quantitative description of the extent and effect of the wintcr hunting and 40 j . durinck & k . falk 40 -3fl % so{ fulmarus glacialis + alle alle + n-684 % 604 puffinus aravls -0.5 0.6-1 1.1-1.5 1.6-2 2.1-2.5 2.6 temperature ranges t -0.5 0.6-1 1.1-1.5 1.6-2 2.1-2.5 2.6 temperature ranges t -0.5 0.6-1 1.1-1.5 1.6-2 2.1-2.5 2.6 temperature ranges t x , 10 0 . 5 0 6 1 1.1-1.5 1.6.2 2.1-2.5 2 6 temperature ranges t -0.5 0.6-1 11-1 5 1 6 2 2 1-2.5 2.6 temperature ranges t -0.5 0.6-1 1.1-1.5 1.6-2 2.1-2.5 2.6 temperature ranges ‘c uria lomvia n-2768 20 10 -0.5 0.6-1 1.1-1.5 1.6-2 2.1-2.5 2.6 temperoture ranges t -0.5 0 6 1 1.1-1.5 1.6-2 2.1-2.5 2.6 temperature ranges “c fig. 16. proportional distribution of seabirds observed within specific ranges of sea surface temperature off southwestern greenland september 1988. positively significant association (95%) for range indicated by “+” while “-” indicates negative significance. blank indicates “not significant”. the distribution and abundance of seabirds off southwestern greenland 1988-1989 41 x 75 50 25 ;5 1 somaterla spectabllls ice cover in vlo n-502 25 _ 1 2 3 4 5 6 7 8 9 ice cover in !/lo % * ice cover in 1/10 i , 10 . . 1 2 3 4 5 6 7 8 9 ice cover in 1110 i , 1 2 3 4 5 6 7 8 9 ice cover in 1110 1 2 3 4 5 6 7 8 9 ice cover in l/lo i 50 cepphus grylle x 1 2 3 4 5 6 7 8 9 -ice cover in l/lo 1 2 3 4 5 6 7 8 9 ice cover in l/lo------ x 1 2 3 4 5 6 7 8 9 ice cover in 1110 1 2 3 4 5 6 7 8 9 -ice cover in 1110 fig. 17. proportional distribution of seabirds observed within specific ranges of ice cover (1/10 to 9/10) off southwestern greenland february 1989. positively significant association (95%) for range indicated by “+” while “-” indicates negative significance. blank indicates “not significant”. 42 j . durinck & k . falk gill-net fishery upon the brunnich's guillemot population of greenland", funded by the commission for scientific research in greenland and initiated by the zoological museums green land investigations, copenhagen. we are indebted to the greenland military command for access to their fisheries inspection vessels and other logistic help. we also wish to thank lvittut municipality for additional funding to carry out field work and r. g . b. brown for making unpublished material available. references anonymous ed. 1976: rapport nr. 4. registrering af beva ringsvzrdige omrpder/nalunaerusiak nr. 4. nunanik avdlangutsailiugagssanik, nalunaerkutsersuinek. grcdnlands tekniske organisation (gto), arbejdsgruppen vedrerende kondccionshavcres tekniske aktiviteter i grcdnland. boertmann, d . 1979: ornithological observations in west greenland 1972-77. dansk o m . foren. tidsskr. 73, 171 176. boertmann, d. 1994: an annotated checklist to the birds of greenland. medd. grmnland, biosci. 38. 63 pp. brown, r. g . b . 1970: fulmar distribution: a canadian perspective. ibis 112, 44-51. brown, r . g . b. 1986: revised atlas of eastern canadian seabirds. 1 shipboard surveys. can. wildl. serv., ottawa. brown, r . g. b . , nettleship, d . n . , germain, p., tull, c. e . & davis, t. 1975: atlas of eastern canadian seabirds. can. wild. serv., ottawa. 220 pp. brown, r. g . b . , barker, p. s . gaskin, d . e. & sandeman, m. r . 1981: the foods of great and sooty shearwaters (pufinus gravis and p. griseus) in eastern canadian waters. ihis 12.?, 19-30. buch, e. 1990: a monography of the physical environment of the greenland waters. greenland fish. res. inst. duplicated report. 450 pp. christensen, 0. & lear, w. h . 1977: bycatches in salmondrift nets at west greenland in 1972. medd. gr0nland205. 38 pp. evans, p. g . h. 1984: the seabirds of greenland: their status and conservation. pp. 49-84 in croxall, j. p., evans, p. g . h. & schreiber, r. w. (eds.): status and conseruation of the world's seabirds. icbp tech. publ. 2. cambridge. evans, p. g. h & waterston, g . 1976: the decline of the thick-billed murre in greenland. polar rec. 18, 283-287. evans, p. g . h. & kampp, k. 1991: recent changes in thick billed murre populations in west greenland. pp. 7-14 in gaston, a . j . & elliot, r . d (eds.): studies of high-lattitude seabirds. 2 . conservation biology of thick-billed murres in the north-west atlantic. can. wildl. serv. occ. pap. 69. falk, k. & durinck. j . 1991: the by-catch of thick-billed murres uria lomuia in salmon drift-nets in west greenland in 1988. pp. 2s-28 in gaston, a. j . & elliot, r . d (eds.): studies of high-latitude seabirds. 2. conservation biology of thick-billed murres in the north-west atlantic. can. wildl. seru. occ. pap. 69. falk, k . & durinck, j . 1992: thick-billed murre hunting in west greenland, 1988-1989. arcric 45, 167-178. 111 pp, falk, k. & durinck, j . 1993: the winter diet of thick-billed murres, uria lornuia. in western greenland. 1988-1989. can. j . zool. 71, 2644212. franeker, j. a . van & wattcl, j . 1982: geographical variation of the fulmar fulmarusglacialis in the north atlantic. ardea 70. 31-44. glahder, c. 1993: havfugle langs syd og syd0st g r ~ n l a n d , august 1990. dansk o m . foren. tidsskr. 87, 252-254. gm & o c 1993. database over gr0nlands haufuglekolonier. grcdnlands miljounders0gelser (greenland environments1 research institute & ornis consult), copenhagen. 22 pp. iianey, j. c. & solow, a. r. 1992: testing for resource use and selection by marine birds. j . field ornith. 63, 45-52. joensen, a . h . & preuss, n . 0. 1972: report on the ornitho logical expedition to northwest greenland 1965. medd. grmland 191. 58 pp. kampp, k. 1990: the thick-billed murre population 0 1 the thule district, greenland. arctic 43, 115-120. kampp, k . , nettleship, d . n. & evans, p. g . h. 1994: thick billed murres of greenland: status and prospects. pp. 133 154 in: nettleship, d . n . , burger, j . and gochfield, m. (eds.) birdlife conservations series no. i:seahirds on islands: threats, case studies'and action plans. birdlife international cambridge. mclaren, p. l. 1982: spring migration and hahitat use by seabirds in eastern lancaster sound and western baffin bay. arctic 35, 88-111. mclaren, p. l. & renaud, w. e. 1982: seabird concentrations in late summer along the coasts of devon and ellesmere islands, n. w. t. arctic 35, 112-117. pihl, s. 1976: some observations of birds in southwest green land 197s75. dansk o m . foren. tidsskr. 103-106. renaud, w. e . , mclaren, p. l. & johnyon, s. r. 1982: the little auk alle alle as a spring migrant in eastern lancaster sound and western baffin bay. arctic 35, 11%125. salomonsen, f. 1950: the birds of greenland. munksgaard. kdbenhavn. 609 pp. salomonscn, f. 1965: the geographical variation of the fulmar fulmarllr glacialis and the zones of marine environment in the north atlantic. a u k 82, 321-355. salomonsen, f. 1979: ornithological and ecological studies in s. w. greenland (59"46'-62"07' n. lat.). medd. grgnland 204. 214 pp. skov, i t . , durinck, j., danieben, f. & bloch, h. 1994: the summer distribution of procellarriformes in the central north atlantic ocean. vogelwarte 37, 270-289. skov, h. durinck. j . , leopold, m.f. & tasker, m.l. 1995: important bird areas for seabirds in the north sea. birdlife international, cambridge. 156 pp. tasker, m. l., jones, p. h., dixon, t. & blake b . f. 1984: counting birds at sea from ships: a review of methods employed and a suggestion for a standardized approach. auk 101, 567-517. tull, c.e., germain, p. & may, a . w. 1972: mortality of thick-billed murres in the west greenland salmon fishery. nature 237, 42-44. webb, a . & durinck, j . 1992 counting birds from ship. pp. 24-37 in komdeur, j . , bertelsen, j . & cracknell, g. (eds.): manual for aeroplane and ship surveys for waterfowl and seabirds. iwrb spec. publ. 19. slimbridge, uk. holocene sedimentary rocks in mathiesondalen, central spitsbergen, svalbard 0. lauritzen and 0. salvigsen lauritzen, 0. & salvigsen, 0. 1983: holocene sedimentary rocks in mathiesondalen, central spitsbergen, svalbard. polar research 1 n . s . , 151-155. holocene lithified sediments of glacial and glaciofluvial origin have been found in environments where carbonate cementation is a present-day process. the rocks occur as well cemented tillites, conglomerates. coarse sandstones and breccias, indicating a complex depositional pattern within a limited area. both clasts and carbonate cement are mainly derived from underlying carboniferous and permian sequences which form the bedrock of this area. qrnulf lauritzen and otto suluigsen, norsk polarinstitutr, rolfstangueien 12. 1330 oslo lufthaun, norway; january 1983 (revised june 1983). introduction during the summer 1981, members of the norsk polarinstitutt’s expedition to svalbard visited mathiesondalen in biinsow land in central spits bergen (fig. 1). the bedrock in mathiesondalen consists of gently dipping carboniferous and per mian limestones and dolomites. sequences in the valley floor belong to the ebbadalen and nor denskioldbreen formations (cutbill & challinor 1965), and consist of dolomites with anhydrite passing up into calcitic limestones. outcrops of these sediments are uncommon near the coast where there is quaternary cover. however. exposures are found along the streams in the inner parts of the valley. during a general survey of the area, several outcrops of well cemented, lithified young sedi ments were found in scattered exposures along the whole length of the valley (fig. 2 ) . these rocks have not been reported earlier, even though parts of the quaternary succession have been studied by feyling-hanssen (1955,1965), boulton (1979), and troitsky et al. (1979). well cemented young sedimentary rocks have been observed elsewhere in svalbard, but never described. although such rocks usually occur as carbonate cemented breccias in talus deposits, the deposits described here are sediments of glacial and glaciofluvial origin, located on the valley floor. description both cemented and unconsolidated rocks with the same depositional origin occur in association on the valley floor. the present regime of the valley is evidently glaciofluvial with braided streams depositing sediments showing great sim ilarities t o some of the carbonate cemented rocks. the degree of cementation is variable, and non-consolidated beds abut well cemented rocks. the well cemented rocks can be divided into three main types: bedded sedimentary breccias, conglomerates/sandstones, and tillites. these three rock types occupy discrete parts of the valley floor as indicated in fig. 2. breccias the breccias occur in the outermost part of these valley deposits, approximately 6 m above sea level. the best exposure is seen in a 12 m thick bedded succession which is evidently part of a delta foreset, with individual co-sets 1.5 to 1.6 m thick, each co-set fining upwards (fig. 3). the material is polymict, angular, and poorly sorted. clasts are normally less than 25 cm, but some few boulders of 35 to 45 cm are found. more clasts are bioclastic limestones, with a fossil con tent typical of the carboniferous and permian beds in the area, and one rugose coral has been 152 0. laurirzen and 0. salvigsen location m a p *s kv~'"yao fig. i . location map in svalbard found as a separate clast. rare clasts of gypsudanhydrite are also seen, while dolomites, cherts and silicified limestones are relatively com mon. only a few fragments of hecla hoek rocks and no devonian rocks have been found, there may be a weak preferred orientation among some of the more elongated clasts, parallel to the foreset bedding. conglomerateslsandstones the conglomerate and sandstone beds are located in the central part of the valley floor, best exposed north of the present river (fig. 4). this facies represents the glaciofluvial regime of mathieson dalen, but the deposits are capped by tills (see fig. 2 ) . the g!aciofluvial deposits are well bedded. the conglomerates are polymkt. with well rounded pebbles dominated by fossiliferous lime stones of local origin. the pebbles vary in size from 1 to 10cm. but individual beds are well sorted. sandstone dominated horizons occur interbed ded with the conglomeratic beds. the coarse sand fraction consists both of limestone and quartz or chert. the conglomerates and sandstones are found in approximately 0.5 m thick beds, and internal structures are evident within the sand stone horizons. some beds represent trough infills, with sand at the bottom coarsening up to pebbles in the top layers. some imbrication was observed. tillites a 10-12 m high exposure of tillite rises above the valley floor (see figs. 2 and 5 ) , resting on a sandstone. the tillite exhibits no bedding and is laterally overlain by unconsolidated till, although good contacts are not seen at this major exposure. observed sedimentological environments ~ d e l t a ~ braided ~ g l a c i a l ~ braided glacial f r o n t , s t r e a m i , stream ; ' w e l l : c e m e n t a t i o n m o s t l y i c e m e n t a t i o n ; t i l l i t e covered by till ; c e m e n t e d ' c o n f i n e d t o till 1 c o n f i n e d t o ; ~ c e r t a i n beds ~ t i l i t i l l ~ c e r t a i n beds ~ : l i t e j 14511 sea l e v e l fig. 2 sketch of thc bections exposed along the river of maihiesondalen. where both well cemented and non-cemented deposits occur the sections exhibits glacial and glaciofluvial deposits covered by raised beach sediments. figure not in scale. holocene sedimentary r o c k s 153 fig. 3. delta front foresets, as they appear in the outer part of mathiesondalen. their lithol ogy is similar to that of breccias, but exhibits well developed bedding. fig. 4. conglomerates and sandstones in a bedded braided river sequence. well cemented rocks occur along with non cemented ones along the pres ent day river bed. fig. 5. tillite as found in the inner part of mathiesondalen. the rock is well cemented and stands up from the valley floor. 1.54 0. lauritzen and 0. saluigsen the tillite is, however. exposed further north wards along the stream overlain by unconsoli dated till. this contact between the tillite and the till is crucial for the understanding of the age relation ship of these rocks. one boulder is found in both till and tillite; the lower part of it is stuck in the tillite, while the upper part is surrounded by unconsolidated till (fig. 6), exhibiting that these two units belong to the same sedimentary sequence and episode. the unconsolidated till can further be followed up to the present glacier, which is only a couple of hundred metres awav. thin sections thin sections from all three lithofacies show obvious similarities as regards cement and lithi fication. all sections were coloured with alizarin red, and the rim of calcite cement around all clasts thus showed great contrast to the other minerals. these sediments are highly porous and some beds disintegrate on disturbance. discussion and conclusion these lithified units reflect the cementation pro cesses active in a limited limestone area of sval bard. we also know that solution of sulphatic bedrock with formation of karstic features is a fig. 6. this figure exhibits the tillite covered by till. the block’s lower part is cemented in the tillite. while the upper part is within the unconsoli dated till above. both till and tillite belong to the same sedi mentological event. presently active process in the valley (salvigsen et al. 1983), but we cannot relate these dissolved elements to the cementation discussed here. we know that carbonate cementation is active in some areas, but such observations from sval bard are mostly scattered and local. in mathie sondalen, however, we have for the first time found a larger area, where systematic observa tions were possible. although observations were located to one valley floor, we feel that the dif ferent regimes compensate for the lack of regional distribution. the carbonate-rich bedrock of the area plays a major part in this process, supplying the sedi ments along the valley floor with the cement needed. the cool climate of this high arctic area accelerates precipitation of the calcite, a fact stressed by swett (1974) in a work on calcrete crusts in a permafrost environment in central east greenland. at the present stage, we cannot explain properly why this process acts so selec tively in apparently similar beds. one bed may show no cementation at all, while the next one is completely cemented and lithified. little is known about the thickness of these lithified sediments, but it is evident that a large number of them have permafrost. permafrost is apparently an effective barrier for the ground water percolation, and it is difficult to understand how solutions and cement can be distributed within the permafrost layer. the age determination of these rocks is a matter holocene sedimentary rocks 155 of great importance, but unfortunately no fossil material was found in any of the carbonate cemented units. however, there is shell material in the marine, unconsolidated beds above, reveal ing a holocene age of these raised beach deposits (salvigsen et al. 1983). we attach great import ance to the fact that one of the tillite exposures shows both cemented and non-cemented material, showing a gradual transition from one stage to the next. in this locality a boulder more than 0.5 m in diameter is cemented in the under lying tillite, while the top stays within the uncon solidated till (fig. 6). this find indicates that the till above and the tillite below were deposited during the same sedimentological event, probably during the last deglaciation of the area. indica tions of erosional contact between cemented and non-cemented deposits were not seen. we mean to point out from our observations that the carbonate cementation of these rocks commenced during the holocene, and to indicate that this process is still active in the area today. acknowledgement. we are grateful to dr. david worsley for improving the english text and to espen kopperud for pre paring the figures. references boulton, g. s . 1979: glacial history of the spitsbergen archi pelago and the problem of the barents shelf ice sheet. boreas 8, 31-57. cutbill, j. l. & challinor, a . 1965: revision of the strati graphical scheme for the carboniferous and permian rocks of spitsbergen and bjorn0ya. geol. m a g . 102,41&439. feyling-hanssen. r. w. 1955: stratigraphy of the marine late-pleistocene of billefjorden, vestspitsbergen. norsk polarimtitutt skrifter n o . 107. feyling-hanssen, r . w. 1965: shoreline displacement in central vestpitsbergen. n o r s k polarinsrirurr meddelelser n r . 93, 1 5 . salvigsen, o . , lauritzen, 0. & mangerud, j . 1983: karst and karstification in gypsiferous beds in mathiesondalen, central spitsbergen, svalbard. polar research i n.3. swett. k. 1974: calcrete crusts in an arctic permafrost environ ment. a m . j . sci. 274, 1059-1063. troitsky, l . s . , punning, j . m . . hutt. g . & rajamae, r. 1979: pleistocene glaciation chronology of spitshergen. borells 8, 401-407. structure and heat content of the west spitsbergen current peter m. haugan the seasonal evolution of the hydrographic structure of the west spitsbergen current (wsc) above bottom depths from 300 m to 800 m is discussed based on a modem data set with high spatial resolution. the wsc appears to have a core with high temperature and salinity, linked to the topography in this depth interval, with a width on the order of 10 km. strong cooling occurs i n the autumn, reducing the heat content of the upper 200 m, but advected temperature and salinity maxima survive close to the surface in spring when air-sea exchange and vertical mixing is hampered by sea ice and meltwater. p. m . hrrugari, geophysical institute, unirjersity qf bergen, allegaten 70, n-5007 bergen, nonvay. introduction the west spitsbergen current (wsc) is the northernmost extension of the norwegian atlantic current which is known to transport substantial amounts of heat from the north atlantic into the arctic mediterranean. fram strait contains the northernmost permanently ice-free ocean area on earth. global coupled model greenhouse gas scenario runs (washington & meehl 1996) in dicate warming in the continuation of the wsc in the atlantic layer of the arctic ocean and reduction of ice cover with implications for global albedo. arctic ice extent has reduced and the temperature of the atlantic layer has increased in recent years (grotefendt et al. 1998), apparently linked to warming of the deep water i n the greenland sea and changes in the atmospheric circulation towards north-west europe expressed as an increased north atlantic oscillation (nao) index (hurrell & van loon 1997). if such tentative large-scale patterns and links are significant in the natural or perturbed climate system it seems that the wsc must play an important role as the mediator between the north atlantic oceanic system and the arctic. this paper is concerned with the inner part of the wsc which feeds the coastal branch shown in fig. 1, subducting below the surface and continu ing into the arctic ocean as the atlantic layer. while the outer parts of the wsc over deep water may be dominated by large baroclinic eddies and recirculate in complex ways difficult to monitor, it is our hypothesis that the inner branch over the continental slope may be suitable to time series observations and perhaps respond in meaningful ways to large-scale forcing anomalies. the hydrography over the continental slope of west spitsbergen in the depth interval 3 0 0 m to 800 m was studied. the shallow depth limit was chosen because it eliminates shelf observations clearly east of the wsc core while still allowing detection of the shoreward extent of the current and its mixing with shelf water. the deep depth limit was selected to allow detection of the boundary between atlantic water above inter mediate water. the present state is examined on the basis of a recent high quality seasonal data set with high spatial resolution. processes involved in determining the structure of the wsc, relations to the few published seasonal data available, and requirements for future monitoring are briefly discussed. observations most recent measurement campaigns (e.g. gascard et al. 1995; w. walcowski, pers. comm. 1998) have been performed in summer; the november data of aagaard et al. (1987) and the january haugan 1999: polar research 18(2), 183-188 183 fig. 1. branching of the wsc according to gascard et al. (1995). the location of our repeat section (from 77"38'n. 10"33'e to 77"39'n, io"45'e) is indicated. february data of boyd & d'asaro (1994) are notable exceptions. between the summers of 1997 and 1998, we monitored the wsc with detailed hydrographic observations using a seabird ctd system. a cruise planned in february 1998 had to be cancelled since the ship had technical difficul ties in the very cold weather (around -30°c) at the time. during a cruise which was completed in aprilmay, heavy drift ice made it impossible to navigate into fixed positions on the shelf slope. the ice conditions along the west coast of spitsbergen were heavy in winter and spring 1998 with much multi-year ice until the last week of may. stations were established over 300 m, 400 m, 500m, 600m, 700m and 800m depths on the section marked in fig. 1 on 20 september 1997, 19 november 1997, 3-4 june 1998 and 4 september 1998. the section is perpendicular to the top ography and only 9 k m long stretching from approximately 77"38'n, 10"33'e to 77"39'n, 10"45'e. the station spacing is 1.5 km except in the shallowest part where the slope is less steep. the numerical value of the slope is at a maximum of about 0.07 in the depth interval 400 m to 800 m and decreases again to about 0.03 between 1000 m and 2000 m depth. the late november and early june cruises can be considered as taking place at the beginning and end of winter, respectively, while the september data are representative of the local summer peak. figure 2 shows the seasonal evolution of temperature, while salinity is shown in fig. 3. detailed profiles and a temperature-salinity dia gram from the 600m depth station are shown in fig. 4. there is an average reduction in tempera ture of about 1°c in the upper 200 m during the two months from september to november (figs. 2a, b). the cooling has been associated with a reduction in salinity on the order of 0.1 psu (figs. 3a, b), so that the core salinity above 35 is now only present in a thin layer below 200m. the freshening may be due to in-mixing of sea ice meltwater from the western barents sea or influence from coastal water. the rate of reduction i n local upper ocean heat storage corresponds to a net heat release of about 150 wm-' during the two month period. this time rate of change term is a significant contribution to the surface heat budget i n the autumn. it comes in addition to ocean heat flux divergence, which i n principle can be determined from observations of northward cool ing and current velocities (aagaard et al. 1987; boyd & d'asaro 1994). in early june, water warmer than 4°c extends upwards to only 2 0 m depth, capped by a thin surface layer affected by sea ice meltwater (fig. 2c). the high temperature water obviously origi nates from the northward flow of the wsc from warmer, ice-free regions further south. it can be seen from the shallow and strong salinity maxi mum (fig. 3c) that there has been little mixing i84 structure and heat content of the west spitsbergen current f i g . i?. temperature sections: (a) september 1997; ( b ) november 1997; ( c ) june 1998: and (d) september 1998. with the low salinity surface water, which has been isolated from the water below by a strong density stratification at the base of the mixed layer (not shown). in contrast, the shallow mixed layer observed in november. rests on top of a much more gradual and monotonous stratification in temperature and salinity, probably the result of previous vertical mixing events induced by transient wind forcing of the shallow mixed layer. the highest temperatures and salinities in june occur over the slope region, but not further west above deeper water (figs. 2c, 3c). this structure would be consistent with a swift jet situated over the strong topographic slope and weaker north ward flow on the shelf and offshore. but it could also b e that further west, the extreme properties have been eroded more strongly by isopycnal mixing or wind mixing from the surface. in september 1998 the upper 50 m was almost 2 c warmer than in september 1997 (figs. 2a, d, 4a). the survey in 1997 was 16 days later in the year than that in 1998, but the cooling rate of 0.5’c per month estimated during autumn 1997 cannot explain more than a small fraction of this difference, which is ascribed to interannual variability. approximately neutrally buoyant, cold, low salinity anomalies occur on scales of 1-2km in the horizontal and 10 m in the vertical, notably on the 600 m depth station at around 180 m depth in june, (figs. 2c, 3c), and at around 90 m depth in september 1998 (figs. 2d, 3d, 4a, 4b). it is proposed that the origin of these anomalies must be on the shelf east of the main core of the wsc, and that they propagate along isopycnals offshore into the wsc. the detailed mechanisms of transport and their role in cooling and dilution of the wsc remain speculative. as illustrated in fig. haugan 1999: polar research 18(2). 183-188 185 ,./' .7w ,/" /' // fc) saiinltv fmm wsc slom jun 98 -p' a 4 7 2 3 4 5 8 7 8 dmanca (km) ,." -700 /' 1 / " w o ' i 2 3 4 5 tl 7 b 0 distance (krn) f i g . 3. salinity sections: (a) september 1997; (b) november 1997: (c) june 1998; and (d) september 1998. 4c, the water column is always stable with possibilities for marginal instability associated with these intrusions of cold, low salinity water. discussion the structure of the inner parts of the wsc seems similar to that reported by orvik et al. (1995) for the norwegian atlantic current in the lofoten vesterilen area, i.e. a topographically steered, significantly barotropic current. the direct current measurements by orvik et al. show a core over a similar depth interval along the slope as discussed here based only on hydrography. although the distance to the upstream sections in the norwegian sea is considerable, there is a continuity between the two current systems, and similar driving mechanisms may be at work. the continental slope west of spitsbergen is quite steep in this depth interval. topographic steering is theoreti cally expected to be particularly important for high latitude currents based on conservation of potential vorticity. however, significant upslope motion has been reported by richez (1998) north of our study area close to the yermak plateau. the mechanisms behind such motion are partly unknown, and not necessarily applicable to the steep slope area where our measurements have been taken. the observed temperature and salinity maxima at tached to the topographic slope could be recon ciled with upslope motion if water mass modification on the shallow shelf is accounted for. the data of aaagaard et al. (1987), collected on 20-27 november 1977 at 79" and 80"n, showed temperature maxima of 3.5 to 4°c between 100 m and 200 m depth and maximum salinities close to i86 structure and heat content of the west spitsbergen current f i g . 4. temperature and salinity observations from the station at 600 m depth, september 1997 (thickest line), november 1997 (intermediate line thickness). june 1998 (dashed line), september 1998 (thinnest line): (a) temperature profiles: (b) salinity profiles; (c) temperature-salinity diagram, with potential density isolines included. 34.975 between 200 m and 300 m depth. these are close to the values of our november data obtained in another year and 150-3ookm upstream. the data of boyd & d’asaro (1994), collected in january and february 1989, show core tempera tures above 4°c close to our repeat section. while, again, unknown interannual variability cannot be accounted for in comparisons, it does appear possible that such temperatures could have prevailed also in january-february 1998, i.e. that advectively generated local warming occurs below sea ice in winter. expecting heat loss over open water to be strongest in winter, the upstream conditions should provide warmer source waters for the wsc in fall than in spring. nonetheless, assuming constant current speed, the data suggest that the early june situation with warm, saline water in the wsc subducted below surface meltwater seems more favourable for heat transport further north, and eventually into the arctic ocean, than the late november situation with a deeper mixed water column giving up large amounts of heat to the atmosphere locally. the situation may be more haugan 1999: polur research 18(2), 183-188 187 complex however, since seasonal variation in current speed may be significant. morison (1991) reported seasonal variations in barotropic currents on the order of 10 c d s based on data from bottom pressure recorders during 1982 to 1985 north-west of spitsbergen, with strongest current speeds in late fall, possibly related to maxima in wind forcing during that season. ice conditions in spring 1998 were severe in the area, but in summer and early autumn, near surface water was warm west and north of svalbard (data not shown here). a possible explanation may be that the temperature in the wsc below the sea ice is kept high when large amounts of meltwater prevent vertical mixing, and that rather than giving up heat to the atmosphere or to ice melting, these warm waters penetrate with small modifications further north and become available for solar heating when the sea ice has finally disappeared. conclusions the observational coverage of the seasonal cycle is limited, but has revealed strong cooling in the autumn and the persistence of strong temperature and salinity maxima at the end of winter. it is proposed that heavy ice conditions west of spitsbergen during spring, generating a stable surface meltwater layer and consequent reduction in heat loss from the wsc, could lead to increased heat transport into the arctic ocean during summer. such seasonal sea ice modulation of the advective heat transfer to the interior arctic could also have interannual signatures in that heavy ice west of spitsbergen in spring would precondition warm summers north of svalbard. much deeper studies and further monitoring of this coupled atmosphere-ice-ocean system is needed not only for climate change detection, but even for achiev ing the more modest aim of understanding the seasonal cycle and its interannual variations. acknowledgements. the captains and crew of lance, polarsyssel and h&on mosby as well as unis staff and students made the cruises pleasant. vigdis tverberg of unis has been a key person in establishing the unis ctd system and procedures for data analysis. the cruise in september 1998 was carried out in collaboration with harald svendsen of the geophysical institute, university of bergen. references aagaard, k., foldvik, a. & hillman, s. r. 1987: the west spitsbergen current: disposition and water mass transforma tion. j. geophys. res. 92(c14), 3778-3784. boyd, t. j. & d’asaro, e. a. 1994: cooling of the west spitsherg.cn current: wintertime observations west of sval bard. j. geophys. res. 9 9 ( c l l ) , 22597-22618. gascard, j. c., richez, c. & rouault, c. 1995: new insights on large-scale oceanography in frarn strait: the west spitsber gen current. in w. 0. smith & j. m. grebrneier (eds.): arctic oceanography: marginal ice zones and continental shelves. pp. 131-182. washington d.c.: american geophysical union. grotefendt, k., logemann, k., quadfasel, d. & ronski, s. 1998: is the arctic ocean warming? j. geophys. res. 103(c12), 27679-27687. hurrell, j. w. & van loon, h. 1997: decadal variations in climate associated with the north atlantic oscillation. clim. change 36, 301-326. morison, j. 1991: seasonal variations in the west spitsbergen current estimated from bottom pressure measurements. j. geophys. res. 96(c10/, 18381-18395. orvik, k. a,, lundberg, l. & mork, m. 1995: topographical influence on the flow field off lofoten-vesterilen. in h. skjoldal et al. (eds.): ecology of fiords and coastal waters. pp. 165-175. amsterdam: elsevier science. richez, c. 1998: the west spitsbergen current as seen by sofar floats during the arctemiz 88 experiment: statistics, differential kinematic properties, and potential vorticity balance. j. geophys. res. 103(c8), 15539-15565. washington, w. m. & meehl, g. a. 1996: high-latitude climate change in a global coupled ocean-atmosphere-sea ice model with increased atmospheric coz. j. geophys. res. 101(08), 12795-12801. 188 structure and heat content of the west spitsbergen current penetration of ultraviolet b, blue and quanta irradiance into svalbard waters e w i n d aas and jo hbkedal aas, e. & hekedal, j. 1996: penetration of ultraviolet b, blue and quanta irradiance into svalbard waters. polar research 15 (2), 127-138. observations from august 1991 and 1993 of downward uv-b, blue and quanta irradiances, and of colour indices and secchi disc depths in the greenland sea and the northern part of the barents sea, are presented. the uv-b irradiance (306 nm) is on average reduced to 10% of its surface value at 5 metres depth, and to 1% at 10 m. blue irradiance (465 nm) is reduced to 10% at 21 m, and to 1% at 41 m. the integrated quanta irradiance obtains the same reductions at 16 m and 35 m, respectively. these penetration depths correspond to ocean water type 111 in jerlov's classification. they are about twice the values of may-june 1973 observed by aas & berge, but they are half the values observed in september 1979 by hojerslev. this variability may partly be seasonal, caused by the hydrological and light-climate cycles. the uv-b transparency of the svalbard waters seems to be influenced by yellow substance from different freshwater run-offs, and there is probably no single relation between salinity and yellow substance content in this region. statistical relations between the quanta irradiance and the colour index, the secchi disc depth and the blue irradiance differ from one region to another, and from year to year. eyvind aas and j o hgkedal, department of geophysics, university of oslo, p.o. box 1022 blindern, n 0315 oslo, norway. solar ultraviolet radiation is generally divided into three spectral ranges: (1) the extremely harmful uv-c radiation (200-280 nm) which is absorbed almost entirely by the earth's atmosphere, (2) the dna-damaging uv-b radiation (280-315 nm) which is strongly absorbed by the atmospheric ozone, and (3) the both damaging and repairing uv-a radiation (315-400nm) which is only weakly absorbed by the ozone. the observed depletion of polar ozone in the southern and northern hemispheres (fahey 1995) is assumed to lead to increased doses of uv-b radiation at the earth's surface (mckenzie 1995; taalas et al. 1995; zerefos 1995), and this has brought new focus on the impact of uv-b radiation on aquatic life. the amounts of ultraviolet radiation at different depths in the sea may be estimated if the corresponding vertical attenuation coefficient for the surface layer is known (zeng et al. 1993). unfortunately very little systematic mapping of such optical properties has been made. jerlov (1976) has published a figure which shows the regional distribution of optical water types for the world oceans between 70"s and 70"n. a similar map has been presented for the secchi disc depth by shifrin (1988), while simonot & le treut (1986) combine several types of optical observa tions to produce regional distributions of optical water types, secchi disc depths, and vertical attenuation coefficients for blue light (465 nm). none of these maps are suited to predicting the penetration of ultraviolet radiation into the sea, except perhaps for the clearest ocean waters, and none of them extend beyond 70"n. for the svalbard area north of 75"n some irradiance observations in the sea have been published (aas & berge 1976; hojerslev 1980; hojerslev & aas 1991), and a few observations have been made in svalbard fjords (halldal & halldal 1973; hokedal 1993). hojerslev & aas (1991) found that for north atlantic surface waters with a salinity above 35.0 psu, the best fit between the vertical attenuation coefficients k at 310 and 465 nm was obtained by the line k(310) = [0.078 m-'1 + 1.04 k(465). (1) it was also found that in the waters around svalbard with salinities below 35.0 psu, the optical observations deviated from this relation. although it could be presumed that the deviations were due to yellow substance brought into the sea by freshwater run-off, evidence for this hypothesis was lacking. 128 e. aas & j . h@kedal in 1991 different optical measurements were made in the greenland and northern barents seas in collaboration with the norwegian polar in stitute and the norwegian institute for water research ( h ~ k e d a l 1993). the main purposes of the project were to survey the vertical attenuation of uv-b and blue irradiance in this region and to study the influence of the freshwater content on the uv-b attenuation. this paper presents the results of the project. additional measurements made in 1993 have been included. as a useful by-product, relations between the integrated quanta irradiance and the blue irradiance, the colour index and the secchi disc depth were obtained and are compared with similar results from the surrounding areas. instruments one integrating and two single-channel irradiance meters were applied: a quanta irradiance meter manufactured by li-cor, inc., nebraska, a uv-b meter from dansk havteknik a/s, copenhagen, and a blue irradiance meter from the department of physical oceanography at the niels bohr institute, university of copenhagen. the underwater sensor li-l92s(b) measures integrated quanta irradiance in the range 400 700 nm (photosynthetically active or available radiation, par). the properties of this instrument have been described by roemer & hoagland (1981). the sensor of the uv-b meter consists of a quartz diffusor and window, an interference filter, and a photomultiplier. its spectral sensitivity peak lies at 306nm and the band width at half peak value is 10nm. the blue irradiance meter has an opal glass, the standard filter combination bg12 + gg5 from schott, a glass window and a photovoltaic cell. the sensitivity peak lies at about 465 nm, and the band width is 30 nm. details of the construction of the two single channel instruments and of their calibrations with regard to linearity, cosine and immersion effects and spectral sensitivity have been presented elsewhere (hekedal & aas 1994). all three irradiance meters were calibrated against certified standard lamps. the colour index meter, manufactured by dansk havteknik a/s, copenhagen, consists of a sensor that “looks” down into the sea and measures the ratio between the upward scattered blue (446 nm) and bluegreen (514 nm) radiances (jerlov 1974a). the spectral band widths at the two wavelengths are about 17 nm. the method of calibration has been described by aas (1993, 1994). a standard white secchi disc with a diameter of about 30 cm was applied. salinity and temperature were measured with a ctd mark 111 sensor from neil brown. methods and errors of measurement a deck model of the quanta meter served as a reference during all the irradiance measurements. it has been observed for green irradiance in coastal waters (aas 1969) that the deviations from a linear relation between irradiance in air and irradiance at 2 m depth normally are less than 20%, but that in special cases (low sun and uneven cloudiness) they may amount to 70%. from obsenations during clear sky conditions in the mediterranean sea, it was concluded that blue irradiance at 10 m depth varied in the range from 48% to 66% of the surface value for solar elevations in the range 10”-70” ( h ~ j e r s l e v 1974a). this corresponds to a relative variation of f: 16% from the mean value. at 50 m depth the relative variation became f 20%. similarly the relative variation of blue irradiance at 60 m depth below sea ice in the arctic ocean was observed to be only 52% for irradiance fluctuations in air of about 70% (smith 1973). from the 60 m long ship r/v lance, measure ments were made using a bar to keep the irradiance meters at a distance of 5 m from the shipside, 10 m aft of the bow. the side of the ship nearest to the instrument bar reached about 4 m above sea level and 5 m below, the resulting influence of the ship on the calculated vertical attenuation coefficient of downward irradiance, k , was estimated to be of magnitude 0.014.025 m-l (h~kedal 1993). because most of the values obtained for k were greater than 0.1 m-’, it was then assumed that the ship’s influence could be ignored. joseph (1949) and aas & berge (1976) have demonstrated earlier that the signal from the blue irradiance meter is proportional to the downward irradiance at 465 nm (fig. 1). unfortunately it is far more difficult to measure irradiance in the uv-b range. if the ratio between penetration of ultraviolet b, blue and quanta irradiance into svalbard waters 129 e(blue) fig. 1. narrow band irradiance e(465) at 465 nm as a function of the broad band irradiance e@lue) recorded with schott filter bg12 + gg5, based on eight optical stations from the norwegian sea between the surface and a depth of 50 m. both irradiances are normalised against their surface values (aas & berge 1976). lo4 lo4 lo4 1 lrradiance [w m4nm-' j fig. 2. irradiance at 465 nm (right curve) and uncorrected irradiance at 306nm (left curve) as functions of depth, at a station in the central greenland sea (75.0°n, lo.o"w, 1720 gmt, solar altitude 9", 15 august 1991) (hekedal & a a s 1994). the blue and uv-b irradiances increases strongly with increasing depth, even a very small sensitiv ity to blue light in the uv-b instrument may make significant or dominating contributions to the signal (hojerslev 1978). for example the ob served irradiance curves at 306 and 465 nm in fig. 2 tend to become parallel from a certain depth on. the obvious explanation is that the uv-b instrument has a "light leakage" in the blue part of the spectrum. the leakage is quantified by the almost constant ratio z between the irradiances e in the depth range where the two curves are approximately parallel: e(306) e(465) tm at all depths z the "true" uv-b irradiance may then be calculated from the observed irradiances by e(306,t),, x e(306,~),,, ~e(465),~),. (3) the observations were rejected when the correc tion given by the last term of eq. (3) amounted to 50% or more of the observed value. this is demonstrated in fig. 3 which presents the uv-b irradiance of fig. 2 after the corrections have been made. the ratio t, which depends on the shape of the spectral irradiance distribution, varied from one station to another (hokedal & aas 1994). the colour index was recorded by lowering the instrument over the rail. it was observed that the distance between ship and instrument had no significant effect on the colour index. the measurements were restricted to solar altitudes above 15", where the index is practically inde pendent of the sun's position (hojerslev 1974b; jerlov 1974a). overcast conditions will increase the index by about 10% (jerlov 1974a). most of the observations of the colour index were made with an overcast sky and have been suitably adjusted. results observations of the vertical irradiance attenuation during august 1991 irradiance was measured at 29 stations in the greenland sea and in the northern part of the barents sea, and in august 1993 at 23 stations in the same area. the solar altitude was less than 30" at all stations, and often less than 20". the positions were chosen for hydrographical rather than optical reasons. at most of the stations the upper layer acted both as a thermoand a halocline, from the surface or from a few metres depth down to the lower boundary at 10-20 m. many stations also featured a dicotherm at this boundary (fig. 3), which is a characteristic of vertical temperature profiles at high latitudes. the observed salinities 130 e. aas & j . hdkedal temperature [c] 0 1 2 3 4 0 5 8 20 a / /// 30 lo4 lo3 104 lo-' 1 lrradiance [rel. units] ' i 306 ,,'' r i / i i i i 28 29 30 31 32 33 34 35 salinity [psu] temperature (c] -2 -1 0 1 2 /4 0 ' """" ''d ' ' """" '""d 104 106 lo4 103 lo4 lo-' 1 lrradiance [rel. units] 28 29 30 31 32 33 34 35 salinity [psu] at the depths where the irradiance was measured varied in the range from 25.4 to 3 4 . 6 ~ ~ ~ . at a typical station the vertical attenuation decreased with increasing depth (fig. 3). at some stations, however, a distinct two-layer structure was observed in the vertical attenuation, with the boundary at 20-40 m depth (fig. 4). the charac teristic feature of the lower layer was a larger attenuation than in the layer above. most probably this was caused by an internal maximum in particle concentration. such maxima have been observed in svalbard waters for the scattering coefficient (kullenberg 1984; kullenberg & xu 1986) and the mass concentration of suspended particles (forsberg 1983). the present observations demonstrate that the fig. 3. downward irradiances at 306 nm (corrected) and 465 nm, and temperature t and salinity s as functions of depth at the same station as in fig. 2. fig. 4. downward irradiances at 306 and 465 nm, and temperature t and salinity s as functions of depth at a station in the northern barents sea (75.8"n, 28.6"e. 1745 gmt, solar altitude 13", 2 august 1991). irradiance will penetrate deeper in the central part of the greenland sea than in the more peripheral areas (figs. 5-8). no clear pattern can be distinguished in the northern barents sea. the statistical mean values 2 the standard deviations for the depths z306(10%) and z3,&%) (figs. s 6 ) , where the uv-b irradiance is reduced to 10% and 1% of its surface value, are 5 i: 2 m and 10 5 3 m, respectively. the corresponding depths for the blue irradi ance, z46d10%) (fig. 7) and 2465(1%), are 21 5 7 m and 41 ? 20 m. the last depth is partly based on extrapolated values. the mean value and standard deviation of the 10% depths of integrated quanta irradiance, zo(lo%) (fig. 8), become 16 i: 5 m. the depth penetration of ultraviolet b, blue and quanta irradiance into svalbard waters 131 fig. 5. distribution in august 1991 and 1993 of the depths z.3&10%) where the downward uv-b irradiance is reduced to 10% of its surface value. the depths represent one single station or the average of two or three closely situated stations. longitude fig. 6. distribution in august 1991 and 1993 of the depths zj&l%) where the downward uv-b irradiance is reduced to 1% of its surface value. z&%) was not measured at all of our stations, but linear correlation based on 12 stations in 1991 gives for this quantity the approximation zq(l%) = [3 1111 + 22,(10%) (4) with correlation coefficient r = 0.74. the mean value of zo(l%) may then in our case be estimated to be about 35 m. the mean values of z,&l%) and z d l % ) both correspond to water longitude type zzz in jerlov’s optical classification of ocean water (e.g. jerlov 1976). the z(o.l%) depths were usually not measured for the uv-b, blue and quanta irradiances, either because the signals became too small or because the underwater cables were too short. however, z3&0.1%) may be obtained as a crude estimate from the presented values of z3&10%) and z306(l%) by the assumption that semilogarithmic 132 e. aas & j . hcdkedal longitude longitude fig. 7. distribution in august 1991 and 1993 of the 10% depth for downward blue irradiance, z465(10%). fig. 8. distribution in august 1991 and 1993 of the 10% depth for downward integrated quanta irradiance, zdlo%). plots of e(306) versus z become straight lines below z306(1o%): ~ ~ ~ ~ ( 0 . 1 % ) = ~ ~ ~ ( 1 0 % ) + 2(zjo6(l%) ~ ~ ~ ~ ( 1 0 % ) ) = z 3 ~ ( l % ) -z306(10%). influence of freshwater on the w b attenuation if we plot our observed values of k(306) from the svalbard area as a function of the corresponding (s) k(46s) values, the points will not lie on the line described by eq. (l), but they will form a diffuse this estimate works best in optically homogenecloud, situated above the line. this means that ous water. svalbard waters contain optical components penetration of ultraviolet b, blue and quanta irradiance into svalbard waters 133 te 0.6 5 0.4 0.2 0 y 28 29 30 31 32 33 34 35 salinity [psu] fig. 9. calculated values of ak as a function of salinity s for the 38 optical stations where s was available. explanation: 0 = greenland sea, 1991; = northern barents sea, 1991; a = greenland sea, 1993; a = northern barents sea, 1993. the dashed line is the best fit to the observations from the greenland sea in 1991. i i i i i / 0 0 30 . 0 / . 25 ;' . a a 9 p 0 0 0 k 2 0 a( a. % l o ->c' 00 h g 15 a , / / 0 0 . .* n 5 k 20 h g 15 % l o n 5 i i i i i / 0 0 30 25 /. 1 1 . . 0 . 0 0 ;' . 0 0 a( a 0 0.5 0.75 1 1.25 1.5 1.75 2 colour index fig. 10. the 10% depth of integrated quanta irradiance, zdlo%), as a function of the d o u r index at 0 m (symbols as in fig. 9). the dashed line gives the best fit to the observations from 1993. which produce significantly larger vertical atten uation coefficients at 306 nm than at 465 nm. the most likely component in the ocean with such a property is yellow substance (aas & hcikedal 1996). probably eq. ( 1 ) applies to conditions where the content of yellow substance is low, and where the variation in k is due mainly to a varying amount of phytoplankton particles and associated debris. the yellow substance content can be deter mined by spectrophotometric analysis of filtered water samples. because the necessary equipment was not available during our cruises, samples were taken and stored for later analysis, but unfortunately they had by then become contami nated and had to be rejected. this restricts our discussion of the yellow substance to a compar ison with the observed salinity. linear relations between yellow substance and salinity, where the content of yellow substance decreases with increasing salinity, have been observed in the baltic sea by kalle (1949) and jerlov (1955), in the kattegat and skagerrak by hojerslev (1971), and in a section between iceland and nova scotia by walsh et al. (1992). more complex patterns will occur when more than two water types are mixed, as demonstrated by hcijerslev (1980, 1994) and hojerslev et al. (1996). the difference between the observed value of k(306) and the value estimated from the observed value of k(465) by eq. ( 1 ) will be termed a k . ak = k(306),,, k(306),, m k(306),, [0.078 m-'1 1.04 k(465),,,. ( 6 ) if the difference ak is caused by yellow substance, it can then be expected to decrease with increasing salinity. the quantity ak was calculated for the 38 optical stations where data for the salinity s were available. linear correlation restricted to the observations from the greenland sea in 1991 produces the line with the correlation coefficient r = -0.81 (fig. 9 ) . since yellow substance in svalbard waters may originate from local river sources as well as from different run-offs into the arctic ocean and other areas, it is not surprising that observations from other years and other regions deviate from the relation given by eq. (7) in fig. 9 . if ak is assumed to be entirely due to yellow substance, it may be approximated by the expression ak m a y ( 3 0 6 ) / p ( 3 0 6 ) (8) where aa306) is the absorption coefficient of yellow substance, and ~ ( 3 0 6 ) is the mean cosine of the zenith angle for the downwelling uv-b radiance. a crude estimate of the last quantity can be obtained by assuming that the downward uv-b radiance is constant within the snell circle, that is 134 e. aas & j . hflkedal for zenith angles 0 in the range 0 48", and zero outside this range: 48" 0 j sine cose d0 j sin0 d0 = 0.83. (9) 4 3 0 6 ) fz 48" 0 consequently the mean value 0.27 m-' of ak in fig. 9 may correspond to a mean absorption coefficient a,,(306) x 0.22 m-' for yellow sub stance. relations between z ~ ( 1 0 % ) and other optical quantities the euphotic zone may be defined as "that region in which light is sufficient to support the growth and reproduction of plants" (lalli & parsons 1993). from this definition it follows that the lower boundary will vary geographically and for different species. however, as a rule of thumb z&%) is often taken as a measure of the lower boundary for phytoplankton (kirk 1983), and in certain regions and for certain species this may be permitted. the euphotic zone for benthic algae seems to extend to deeper layers than for phyto plankton, and in extremely clear tropical water it even reaches below the 0.001% level (littler et al. 1985). the quantities zo(lo%), zo(l%) and 2 ~ ( 0 . 1 % ) discussed in this paper are then primarely optical (and not biological) properties of the vertical water column. if the quanta irradiance has not been observed, it will be useful to have relations between z&%) and the other optical quantities. in our case the length of the underwater cable did not allow zo(l%) to be observed directly at all stations, so instead relations based on zdlo%) have been studied. when zdlo%) is determined, z d l % ) can be estimated from eq. (4). jerlov (1974b) was the first to point out that a strong correlation usually exists between the transmittances of blue and integrated quanta irradiance in ocean waters with a low content of yellow substance. the present observations from the svalbard waters result in (10) with r = 0.81. our observations of the ratio between the 10% depths of quanta irradiance and the secchi disc z,(lo%) m [6 m] +0.44246~(10%). depth d result in the mean value and the standard deviation z,(lo%)/d f= 1.2 rt 0.3. (11) the colour index f is defined as the ratio lu(446)/lu(514), where l , is the radiance from nadir on the wavelengths 446 and 514nm. it is usually measured at 1 m depth or just beneath the surface. if the correlation analysis between the colour index f , extrapolated to the surface, and zo(lo%) is restricted to the observations from 1993, the result becomes (12) with r = 0.92. the observations from 1991 are not evenly distributed around the line given by eq. (12), as illustrated by fig. 10, and they seem to have a smaller slope. by applying the colour index at 1 m depth the 1993 observations produce z ~ ( l 0 % ) m [-2.0 m] + [17.4 m] f(o m ) zq(lo%) f= [-0.4 rn] + [16.4 m] f(1 m ) (13) with r = 0.93. discussion comparison with earlier investigations during late may to early june in 1973 blue irradiance was recorded at six stations in the svalbard area by aas & berge (1976). on this occasion atlantic surface water (salinity above 3 5 . 0 ~ ~ ~ ) was observed as far north as 76.5"n. the observations gave z4,.@o%) = 7.5 f 3 m in waters with salinities below 35.0 psu, and z46,-(10%) = 16.5 ? 7 m in the atlantic water. similarly z46,-(l%) became 16 ? 7 m for the nowatlantic and 40 f 17 m for the atlantic water. the non-atlantic mean values in 1973 were then less than half of the present observa tions (21 and 41 m, respectively), while the atlantic values were of the same magnitude. the mean values of zdlo%) and z d l % ) could be estimated to be about 8 and 19 m, respectively, for the non-atlantic waters, which again are only about half the present results (16 and 35 m). in september 1979 h~jerslev (1980, 1982a) obtained the value 0.20-0.25 m-l for k(310) in the svalbard area, and this corresponds to a z3,d10%) of 9-12 m and a z3]dl%) of 18-23 m. the observed value of zo(l%) was in the range 50-56 m. these results are all greater than any of penetration of ultraviolet b, blue and quanta irradiance into svalbard waters 135 our observations, and about twice our mean values. the values of the absorption coefficient of yellow substance 375 nm, a,4375), were in the range 0.01-0.02 m-'. the variation of this coefficient with wavelength a may be approxi mated by an exponential function (jerlov 1968; lundgren 1976): a y ( x ) = a y ( x , ) e ~ ( x x o ) . (14) the quantity y varies only slightly with wave length but has a more significant variation in space. in the baltic sea and in the gulf of mexico y has been observed to vary in the range 0.011 0.017nm-' (lundgren 1976; carder et al. 1989) and elsewhere in the range 0.010-0.020 nm-' (bricaud et al. 1981; hpjerslev 1988). if we apply the value o.o14nm-' for y, the ratio a,,(306)/ aj375) becomes 2.6. the 1979 observations will then correspond to a,4306) x 0.03-0.05 m-l, which is an order of magnitude less than our estimated mean value of 0.22 m-'. nyquist (1979) found for baltic waters that a yellow substance concentration of 1 mg/l corre sponded to aa450) = 0.212 m-l, while the obser vations of carder et al. (1989) in the gulf of mexico indicated that aj450) = 0.007-0.13 m-l with the mean value 0.022m-' for the same concentration. the last value is a factor 10 less than the result of nyquist, and due to this uncertainty we have abstained from estimates of the yellow substance concentration. no significant differences in our observations of z306, 2465, and zo were found between the years 1991 and 1993. this might lead to the premature conclusion that the results in figs. 5-8 represent the average conditions for the area, but the observations in 1973 (aas & berge 1976) and in 1979 (hpjerslev 1980) demonstrate that large changes in the optical conditions may occur. the 1973 observations were made from late may to early june, and some of the stations were visibly influenced by plankton blooms. the 1979 ob servations were made in late september, one month later than our observations, and represented a situation with a significantly lower content of yellow substance than in our case, probably due to a stronger influence from atlantic waters. the freshwater run-off from svalbard will normally start in june, obtain its maximum in july-august, and fade away in september (repp 1988); this cycle is likely to influence the biological and optical conditions in the surrounding surface waters. seasonal changes in available daylight may also induce changes in phytoplankton pro duction and thus in the optical conditions. in general the vertical attenuation coefficients may be influenced by the solar altitude. however, because this altitude usually is less than 35" in the svalbard area, the diffuse sky irradiance will always be much larger than the direct solar irradiance in the uv-b and blue parts of the spectrum (baker & smith 1990). as a conse quence the solar influence on the vertical attenuation coefficient in these waters will also be small, and the observed large differences between the three investigations can then hardly be attributed to seasonal changes in the mean solar altitude, but must mainly be due to differences in the absorption coefficient. comparison with adjacent oceanic regions in the atlantic waters of the norwegian sea, hojerslev & aas (1991) found the average value of z31dl%) to be at a depth of 23 m or more, and the maximum depth of 33 m was found north of the faroe islands. this is more than twice the values in the present results from svalbard waters. calkins & thordardottir (1982) have presented values of kuv-s measured in the areas west of iceland. their observations lead to values of zu,&o%) in the range 13 2 6 m, which also are greater than our result. it may be added the uv radiation seems to penetrate to greater depths in the antarctic than in the arctic. gieskes & kraay (1990) reported values of z340(l%) up to 60 m in the weddel sea, and smith et al. (1992) have presented an irradiance observation from the bellinghausen sea where z340(l%) and z3,dl%) were about 35 and 30m, respectively. by applying eq. (14) the result of gieskes & kraay may be converted to z ~ ~ o ( l % ) x 39m, which is 17% less than the corresponding depth of 47 m observed in the gulf of mexico by hojerslev (1985). the last value corresponds to clearer water at 310nm than the clearest natural waters estimated by smith & baker (1981). the smallest observed values of 2310(1%) in natural waters seem to range from 35 cm in a baltic coastal lagoon (piazena & hader 1994) to 17 cm in lake cromwell, qucbec (scully & lean 1994). observations from the norwegian sea and the southern part of the barents sea, including coastal waters (aas 1980), gave the mean value and the standard deviation of z4,alo%) as 17 ? 9 m, and 136 e . aas & j . hdkedal the corresponding values for z465(l%) as 40 ? 20 m. similarly the results for zo(lo%) and za(l%) became 14 2 6 m and 36 t 14 m, respectively. these values are rather close to the present observations. the relation between the 10% depths of quanta and blue irradiance for the same area was obtained as ze(lo%) [3 m] + 0.6324,(10%) (15) with the correlation coefficient r = 0.98 (aas (1980). the values of zo(lo%) estimated by eq. (10) and (15), respectively, will only differ by 1 2 m for svalbard waters. dallakken et al. (1994, 1995) found for their stations, mainly between 15ow-25"e and 70" 75"n in the southern greenland sea, that pre bloom, bloom and post-bloom conditions were quite different. z441(1%) had the pre-bloom mean value 72 m and the post-bloom value 35 m, and the corresponding values for z d l % ) were 53 and 38 m, respectively. the total range of zo(l%) extended from 16 m (bloom) to 66 m (pre-bloom), and the similar range of z4&1%) seems to have been 17-116 m. the post-bloom values resemble the present observations which are classified as jerlov's ocean water type zzi, but the pre-bloom penetration depths are 50-75% greater than our mean values and belong to ocean water type i i . in may 1972 under the ice in the arctic ocean north of ellesmere island, smith (1973) measured the vertical irradiance coefficient at 490 nm to be 0.0444 m-l. the value of z490(1%) would then be about 100 m, which corresponds to the very clear ocean water type ib in jerlov's classification, in contrast to the present mean type 111. it should be noted that also the observations z&%) = 66 m and z4,@%) = 116 m by dall~kken et al. (1995) classify as type zb. from observations at the fladen ground in the northern part of the north sea, hajerslev (1982b) obtained a relation between the colour index at the surface, f(om), and the 10% depth of quanta irradiance, zdlo%), which for our purposes may be more conveniently rewritten as based on data which also includes observations from the north sea, the baltic sea and the belts (h~jerslev & jerlov 1977), coincides better with the present observations: (17) for a variation of f ( l m) in the range from 0.6 to 1.6, the difference between eqs. (13) and (17) becomes 0-2 m. the colour index is closely related to the methods employed in remote sensing. the differences which result from the expressions (12)-(16) and ( 1 3 h 1 7 ) demonstrate that an algorithm obtained for one area in the norwegian sea cannot always be transferred to another without problems. fig. 10 also indicates that the algorithms may vary from one year to another. it may then become far more complicated to estimate the depth of the euphotic zone in these waters by remote sensing than in ocean areas with a low yellow substance content. in the norwegian sea and the southern part of the barents sea the mean value and the standard deviation of the ratio between the 10% depth of quanta irradiance and the secchi disc depth d has been found to be (aas 1980) z,(lo%) = [4 rn] + [12.2 rnlf(1 rn). zp(lo%)/d m 1.5 rt 0.3 (18) the mean value of d around svalbard in the present investigation is 12.5 m, which means that eq. (18) on average will estimate zo(lo%) about 4 m too deep, as compared with eq. (11). here it should be pointed out that although the secchi disc depth is mainly a function of the inherent optical properties, it is also influenced by the conditions at the surface and by the daylight level. the wave height reduces the observed depth (hajerslev 1986), and the reflection of atmos pheric light at the air-water interface has a similar effect. the daylight level decreases with increas ing latitude, and this will increase the liminal contrast threshold of the human eye (blackwell 1946), which again leads to a reduced secchi disc depth. all these effects may have contributed to the difference between eqs. (11) and (18). zq(lo%) = [-22.0 m] (16) + 138.9 m] [f(o rn) + 0.07]0.s conclusions the present investigation, together with the earlier works by aas & berge (1976) and h~jerslev (1980), demonstrate clearly the complexity of the optical conditions in svalbard waters. the mean when f(0m) fluctuates in the range from 0.7 to 1.6, the difference between the estimates of zdlo%) from eqs. (12) and (16) will lie in the range 2-3 m. an equation between f ( l m) and zdlo%), penetration of ultraviolet b, blue and quanta irradiance into svalbard waters 137 1 % depths of the uv-b, blue and quanta irradiances have been observed to vary in the ranges 10-21 m, 1641 m, and 19-53 m, respec tively. observations by dallbkken et al. (1994, 1995) south of 75"n suggest that these ranges may be extended. it is possible that the observed variability is partly or entirely caused by seasonal changes in river run-off and available daylight. for the moment we must conclude that, although we know something of the variability, we do not have sufficient information to estimate the average conditions and the seasonal variations with satisfactory accuracy. studies of the relations between the vertical attenuation coefficients and the surface salinity indicate that yellow substance in the svalbard area originates from different freshwater run-offs. similarities as well as differences in the optical properties between svalbard waters and the adjacent regions have been observed. compar isons of statistical relations between the quanta irradiance and the colour index, the secchi disc depth, and the blue irradiance demonstrate that algorithms obtained for one area in the norwegian sea may result in significant errors in other areas. our results also indicate that such algorithms may vary from one year to another. acknowledgements. the field work and the laboratory analysis were supported by the norwegian polar institute and the norwegian institute for water research (niva), and in particular we recognise t. lqyning and k. s ~ r e n s e n for their significant parts of the optical measurements. we also wish to thank the crew of the w lance for their assistance during the field work, and two anonymous referees who contributed valuable comments to the paper. references aas, e. 1969: on submarine irradiance measurements. rep. dept. phys. oceanogr. no. 6. univ. copenhagen. 47 pp. aas, e. 1980: relations between total quanta, blue irradiance and secchi disc observations in the norwegian and barents seas. pp. 11-27 in kullenberg, g. (ed.): studies in physical oceanography. papers dedicated to professor nils g. jerlov in commemoration of his seventieth birthday. rep. dept. phys. oceanogr. no. 42. univ. copenhagen. aas, e. 1993: calibration of a marine radiance and colour index meter. rep. dept. geophys. no. 87. univ. oslo. 24 pp. aas, e. 1994: a simple method for radiance calibration. pp. 39-44 in wernand, m. (ed.): european workshop on optical ground truth instrumentation for the validation of space borne optical remote sensing data of the marine environment 23-25 nov. 1993. netherlands institute for sea research, rep. no. 1994-3. aas, e. & berge, g. 1976: irradiance observations in the norwegian and barents seas. rep. dept. geophys. no. 23. univ. oslo. 42 pp. aas, e. & hpkedal, j. 1996: properties of marine optical components in the ultraviolet part of the spectrum, rep. dept. geophys. no. 99. univ. oslo. 15 pp. baker, k. s. & smith, r. c. 1990 irradiance transmittance through the air-water interface. pp. 556-565 in spinrad, r. w. (ed.): ocean optics x, 1 6 1 8 april 1990, orlando, florida. spie proc. 1302. blackwell, h. r. 1946: contrast thresholds of the human eye. j . opt. soc. am. 36,624-643. bricaud, a., morel, a. & prieur, l. 1981: absorption by dissolved organic matter of the sea (yellow substance) in the uv and visible domains. limnol. oceanogr. 26, 43-53. calkins, j. & thordardottir, t. 1982: penetration of solar uv-b into waters off iceland. pp. 309-319 in calkins, j. (ed.): the role of solar ultraviolet radiation in marine ecosystems. plenum press, new york. carder, k. l., steward, r. g., harvey, g. r. & ortner, p. b. 1989: marine humic and fulvic acids: their effects on remote sensing of ocean chlorophyll. limnol. oceanogr. 34, 68-81, dall@kken, r., sandvik, r. & sakshaug, e. 1994: variations in bio-optical properties in the greenland/iceland/norwegian seas. pp. 2 6 6 2 7 6 in jaffe, i. s. (ed.): ocean optics xii, 13 15 june 1994, bergen, norway. spie proc. 2258. dallokken, r., sandvik, r. & sakshaug, e. 1995: seasonal variations in the greenland sea: effect of phytoplankton light absorptions. pp. 33-43 in skjoldal, h. r., hopkins, c., erikstad, k. e. & leinaas, h. p. (eds.): ecofogy offiords and coastal waters. elsevier, amsterdam. fahey, d. w. 1995: polar ozone. pp. 3.1-3.52 in ennis, c. a. (ed.): scientific assesment of ozone depletion: 1994. wmo, global ozone res. monitor. proj., rep. no. 37. forsberg, c. f. 1983: sedimentological and early diagenetic studies in the barents sea. thesis, dept. geol. univ. oslo. 75 pp. + appendix, 135 pp. gieskes, w. w. c. & kraay, g. w. 1990: transmission of ultraviolet light in the weddel sea: report of the first measurements made in the antarctic. biomass newsletter 12, 12-14. halldal, p. & halldal, k. 1973: phytoplankton, chlorophyll, and submarine light conditions in kings bay, spitsbergen in july 1971. norw. l bot. 20, 99-108. hojerslev, n. k. 1971: tyndall and fluorescence measurements in danish and norwegian waters related to dynamical features. rep. dept. phys. oceanogr. no. 16. univ. copenhagen. 46 pp. hojerslev, n. k. 1974a: daylight measurements for photosyn thetic studies in the western mediterranean. rep. dept. phys. oceanogr. no. 26. univ. copenhagen. 38 pp. h@jerslev, n. k. 1974b: inherent and apparent optical proper ties of the baltic. rep. dept. phys. oceanogr. no. 23. univ. copenhagen. 89 pp. hojerslev, n. k. 1978: solar middle ultraviolet (uv-b) measurement in coastal waters rich in yellow substance. limnol. oceanogr. 23, 107&1079. hojerslev, n. k. 1980: on the origin of yellow substance in the marine environment. pp. 39-56 in kullenberg, g. (ed.): studies in physical oceanography. papers dedicated to professor nils g. jerlov in commemoration of his seventieth birthday. rep. dept. phys. oceangr. no. 42. univ. copen hagen. 138 e. aas & j . hokedal hojerslev, n. k. 1982a: yellow substance in the sea. pp. 263 281 in calkins, i. (ed.): the role of solar ultraviolet radiation in marine ecosystems. plenum press, new york. h~jerslev, n. k. 1982b: bio-optical properties of the fladen ground: “meteor” flex-75 and flex-76. j . cons. int. explor. mer, 40, 272-290. hojerslev, n. k. 1985: bio-optical measurements in the southwest florida shelf ecosystem. j . cons. int. explor. mer, 42, 65-82. hojerslev, n. k. 1986. visibility of the sea with special reference to the secchi disc. pp. 294-305 in blizard, m. a. (ed.): ocean optics wii, 31 march-2 april 1986, orlando, florida. spie proc. 637. h~jerslev, n. k. 1988: natural occurrences and optical effects of gelbstoff. rep. dept. phys. oceanogr. no. so. univ. copenhagen. 30 pp. hojerslev, n. k. 1994: origin of the kattegat water. pp. 357 365 in jaffe, j . s. (ed.): ocean optics xii, 13-15 june 1994, bergen, norway. spie proc. 2258. hojerslev, n. k. & aas, e. 1991: a relationship for the penetration of ultraviolet b radiation into the norwegian sea. j . geophys. res. 96, 17003-05. hojerslev, n. k., holt, n. & aarup, t. 1996: optical measurements in the north sea-baltic sea transition zone. i. on the origin of the deep water in the kattegat. cont. shelf res. 16, 1329-1342. hojerslev, n. & jerlov, n. 1977: the use of the colour index for determining quanta irradiance in the sea. rep. dept. phys. oceanogr. no. 35. univ. copenhagen. 12 pp. hokedal, j . 1993: svekninga av nedoverretta uvb-irradians i farvanna rundt kong karls land og i gronlandshavet. kdlibreringa av et uvb-irradiansmeter. thesis, dept. geophys. univ. oslo. 75 pp. h ~ k e d a l , j. & aas, e. 1994 calibration of two single-channel instruments for uv-b and blue irradiance. rep. dept. geophys. no. 88. univ. oslo. 17 pp. jerlov, n. g. 1955: factors influencing the transparency of the baltic waters. rep. oceanogr. inst. gothenburg, no. 25. jerlov, n. g . 1968: optical oceanography. elsevier, amster dam. 194 pp. jerlov, n. g. 1974a: significant relationships between optical properties of the sea. pp. 77-94 in jerlov, n. g. & steemann nielsen, e. (eds.): optical aspects of oceanography. aca demic press, london. jerlov, n. g. 1974b: a simple method for measuring quanta irradiance in the ocean. rep. dept. phys. oceanogr. no. 24. univ. copenhagen. 10 pp. jerlov, n. g. 1976: marine optics. elsevier, amsterdam. 231 pp. joseph, j. 1949: iiber die messung des “vertikalen extink tionz-koeffizienten”. dtsch. hydrogr. 2. 2 , 255-267. kalle, k. 1949: fluoreszenz und gelbstoff im bottnischen und finnischen meerbusen. dtsch. hydrogr. z. 2 , 117-124. kirk, j . t. 0. 1983: light and photosynthesis in aquatic ecosystems. university press, cambridge. 401 pp. kullenberg, g. 1984: observations of light-scattering distribu tions in the transition zone to the arctic ocean. rapp. p.-v. rcun. cons. int. explor. mer, 185, 102-110. kullenberg, g. & xu, z. 1986: on suspended matter, as observed by light scattering in the fram strait-svalbard area. neth. j . sea res. 20, 155-161. lalli, c. m. & parsons, t. r. 1993: biological oceanography, 19 pp. littler, m. m., littler, d. s., blair, s. m. & norris, j. n. 1985: deepest known plant life discovered on an uncharted seamount. science, 227, 57-59. lundgren, b. 1976: spectral transmittance measurements in the baltic. rep. dept. phys. oceanogr. no. 30. univ. copen hagen. 38 pp. mckenzie, r. l. 1995: surface ultraviolet radiation. pp. 9.1 9.22 in ennis, c. a. (ed.): scientific assessment of ozone depletion: 1994. wmo, global ozone res. monitor. proj., rep. no. 37. nyquist, g. 1979: investigation of some optical properties of seawater with special reference to lignin sulfonates and humic substances. dr. thesis, dept. anal. mar. chem. univ. gothenburg, 223 pp. piazena, h. & hader, d.-p. 1994: penetration of solar uv irradiation in coastal lagoons of the southern baltic sea and its effect on phytoplankton communities. photochem. photobioi. 60, 4 6 3 4 6 9 . repp, k . 1988 the hydrology of bayelva, spitsbergen. nordic hydrol. 19, 259-268. roemer, s. c. & hoagland, k. d. 1981: immersion effect and cosine collecting properties of li-cor underwater sensors. 11 pp. in: instruction manual. li-185b quantum radio meter, pub 8004-03. scully, n. m. & lean, d. r. s. 1994: the attenuation of ultraviolet radiation in temperate lakes. arch. hydrobiol. beih. 43, 135-144. shifrin, k. s. 1988: physical optics of ocean wafer. am. inst. phys., new york. 285 pp. simonot, j.-y. & le treut, h. 1986: a climatological field of mean optical properties of the world ocean. j. geophys. res. 91, 6642-46. smith, r. c. 1973: optical properties of the arctic upper water. arctic, 26, 303-313. smith, r. c. & baker, k. s. 1981: optical properties of the clearest natural waters ( 2 0 0 4 0 0 nm). appl. opt. 20, 177 184. smith, r. c., prczelin, b. b., baker, k. s., bidigare, r. r., boucher, n. p., coley, t., karentz, d., macintyre, s., matlick, h. a., menzies, d., ondrusek, m., wan, z. & waters, k. i. 1992: ozone depletion: ultraviolet radiation and phytoplankton biology in antarctic waters. science, 255, taalas, p., damski, i., korpela, a,, koskela, t.. kyro, e. & braathen, g. 1995: connections between atmospheric ozone, the climate system and uv-b radiation in the arctic. pp. 4 1 1 4 2 6 in wang, w.-c. & isaksen, i. s. a. (eds.): atmospheric ozone as a climate gas. nato asi series, 32. springer-verlag, berlin. walsh, j. i., carder, k. l. & miiller-karger, f. e. 1992: meridional fluxes of dissolved organic matter in the north atlantic ocean. j . geophys. res. 97, 15625-15637. zeng, j . , jin, z. & stamnes k. 1993: impact of stratospheric ozone depletion on uv penetration into the ocean at high latitudes. pp. 56-63 in eilertsen, h. c. (ed.): underwater light measurements, 29 june 1993, tromsg, norway. spie proc. 2048. zerefos, c. s. 1995: the recent variability of atmospheric ozone in the middle latitudes of the northern hemisphere and solar ultraviolet radiation. pp. 4 4 7 4 5 2 in wang, w.-c. & isaksen, i. s. a. (eds.): atmospheric ozone as a climate 952-959. an introduction. pergamon press, oxford. 301 pp. gas. nato asi series, 3 2 . springer-verlag, berlin. the diets of common and briinnich's guillemots uria aalge and u. zomvia in the barents sea region robert t. barrett, vidar bakken and juri v . krasnov barrett, r. t., bakken, v. & krasnov, j . v. 1997: the diets of common and briinnich's guillemots uria aalge and u. lomvia in the barents sea region. polar research 16(2). 73-84. guillemots uria spp. account for ca. 70% of the total harvest of prey taken by seabirds breeding in the barents sea region. this paper presents guillemot chick diet data collected recently at four localities (finnmark, murman, bjplmplya and spitsbergen) and collates all the data found by the authors in the literature and in the archives of tromspl museum, the norwegian polar institute and kandalaksha state nature reserve. guillemots consume a wide variety of prey and, in comparison to the harvest by predatory fish and marine mammals, their impact on the barents sea ecosystem is considered to be minimal. we point out the need for more systematic collection of data from different regions and at different times of the year before a final impact assessment can be made. robert t. barrett, zoology department, troms# university museum, n-9037 trams#, n o w a y ; vidar bakken, nowegian polar institute, p . o . box 5072 majorstua, n-0301 oslo, notway; juri v. krasnov, kandalaksha state nature reserve, kandalaksha, munnanskaja obl.. russia 184040. introduction the barents sea is one of the most productive marine ecosystems in the world with vast stocks of commercially important fish, seabirds and sea mammals (sakshaug et al. 1994). of the ca. 3.7 million pairs of seabirds (with a biomass of ca. 4200 tonnes) that breed in the barents sea region (as defined by mehlum & gabrielsen 1995), briinnich's guillemots uria lomvia predominate both in numbers (ca. 1.6 million pairs = 43%) and biomass (ca. 2600 tonnes = 61%). they are in addition the major consumer among the barents sea seabirds, taking in the order of 60% of an estimated 2213 tonnes of food consumed daily by breeding seabirds during the summer (mehlum & gabrielsen 1995). when including the ca. 266,000 pairs of common guillemots uria aalge which also breed in the barents sea, the total consump tion by adults and chicks of both guillemot species has been estimated to be ca. 1500 tonnedday or nearly 70% of the total seabird consumption by breeding seabirds (mehlum & gabrielsen 1995). however, guillemots are known to consume a wide variety of prey (erikstad & vader 1989; vader et al. 1990; barrett & krasnov 1996), and this paper addresses the impact guillemots may have on the barents sea ecosystem. it first documents considerable diversity in prey use at four breeding colonies in the southern and western barents sea regions from 198cl-1995 (fig. 1) and evaluates data found in the literature and in the authors' respective institution's archives. regio nal diet patterns are then presented, impact analyses are made and suggestions are given as to where effort should be made in future feeding studies. little emphasis is, however, placed on temporal or inter-species statistical comparisons as these are dealt with in more detail by barrett & krasnov (1996) and barrett et al. (1997), respectively. methods and material most of the recent data concerning the diet of both species during the breeding season were collected by the authors by direct observation of food items brought to the chick by the adults. observations were made from 5-20 m using binoculars. in most cases the food items could be identified to species level. identification controls were made by catching fish-carrying birds with a noose-pole and identifying the food item in the hand. such studies have been carried out on b j ~ m g y a (bear island) (74"21'n, 19"06'e) nearly every year since 1988, on hornoya, east finnmark (70"22'n, 31"lo'e) since 1980 and on kharlov, off the kola peninsula (68"49'n, 37"20'e) since 1985 (fig. 1). 74 r. t. barrett et al. 80’n 70% fig. 1. map of the barents sea showing the four colonies where guillemot diet data were collected by the authors (solid circles) and other localities mentioned in the text. open circles indicate approximate positions of sampling sites listed in tables 1 and l briinnich’s guillemot chick diet was also studied on kovalskifjellet, spitsbergen (77”03’n, 17’17’e) in 1989 (mehlum & gabrielsen 1993) and 1992. in most years, observations were spread over two or three weeks during the main chick feeding period (july) thereby reducing potential errors in shorter-term sampling due to seasonal changes in diet. more details are given by barrett et al. (1997). because briinnich’s guillemots generally land directly on their breeding site, conceal the prey by bowing their heads, and feed their chicks almost immediately on arrival, sample sizes for this species on hornoya and kharlov were often much smaller than for conunon guillemots which commonly hold the fish aloft before feeding the chicks. some stomach samples from adults were also collected from both species on kharlov in 1992 and from briinnich’s guillemots on novaja zemlja (1992) and franz josef land (1993). comparisons of diets between colonies were made using x2 tests, and p-values <0.05 were considered to be significant. when numbers of food items from individual food categories were low in a sample, several categories were com bined before testing. supplementary data gleaned from the literature and the norwegian polar institute, troms@ museum and kandalaksha state nature reserve archives differed so much in degree of quantifi cation that they were impossible to compare directly. furthermore, some of the data were based on observations of chick diet while other data were based on adult stomach samples. because the relationship between chick and adult diet is unknown, chick and adult data are presented separately. results chick diet capelin mallotus villosus, sand eels ammodytes sp., and i-group herring clupea harengus (barrett & krasnov 1996) constituted most of the diet of common guillemot chicks on kharlov, bjornoya and hornoya (fig. 2). there were, however, clear differences among the colonies in the relative composition of the diets. on kharlov, sand eels were the most important prey items fed to common guillemot chicks. in some years, capelin was also important, and, in 1986, dominated the diet (fig. 2). herring fig. 2 . composition (% by number) of diet fed to chicks of common guillemots on kharlov, bjgmgya and horngya. figures above columns = no. of fish counted. 21” indicates that the fish were collected on the neighbouring colony, syltefjord. (see fig. 3 text for english names of prey.) the diets of common and briinnich’s guillemots 75 occurred in some years but generally constituted 110% of the items recorded. in 1995, hemng made up 25% of the fish recorded. on bjarnaya, capelin constituted 90% or more (by number) of the diet in five of the six seasons for which data exists. in the sixth year (1995), capelin made up >60% and the little squid gonatus fabricii accounted for most of the rest (fig. 2). on horngiya, capelin was again the most common prey item caught by common guillemots, while sand eels were regularly eaten but in lower proportions (fig. 2). after 1990, hemng was a periodically important constituent of the chick diet. in nearly all the years for which there is comparable data from hornaya, kharlov and bj~rnaya, there were significant differences in the diet composition among the colonies (x’ > 13, df = 1-3, p < 0.001). the only insignificant differences found were between hornaya and kharlov in 1985 and 1991, but these may have been due as much to the small sample sizes as to the actual geographical differences. while briinnich’s guillemots tended to feed their chicks a much more varied diet than did common guillemots on bj@rn@ya, capelin, sand eels and i-group hemng again made up the samples collected on hornaya and kharlov (fig. 3). on bjamaya, the briinnich’s guillemot samples contained six different prey items (capelin, squid, sculpins (cottidae), polar cod boreogadus saida, blennies lumpenus sp. and eelpouts (zoarcidae)) which occurred in varying proportions. capelin were, however, the most common prey with squid constituting ca. 30% of the food items in three of the five years. there were significant differences between the prey compositions on hornoya and bjornoya in the three years data were collected on both colonies (1989, 1991, 1993, x2 > 30, df = 3, on kovalskifjellet, briinnich’s guillemots fed their chicks almost entirely on polar cod in 1992. two of the 148 food items observed were crustaceans, the only two specimens of this taxa observed fed to chicks in any of the colonies studied. on kharlov, sand eels constituted 100% (in 1992) and 80% (in 1994) of the fish seen. the remaining fish recorded in 1994 were capelin (14%) and hemng (5%). p < 0.001). adult stomach samples of eight adult briinnich’s guillemot stomachs sampled on kharlov in 1992, three contained capelin, two contained herring, two contained gadoids and one contained sand eels. data from the literature chick diet common guillemots on hjelmsoy, west finn mark, fed their chicks almost exclusively capelin in 1983, but in 1984 saithe pollachius virens dominated their diet (vader et al. 1990; tromsgi museum unpubl.). on rost, lofoten, saithe, sand eels and occasionally butterfish pholis gunnellus fig. 3. composition (% by number) of diet fed to chicks of briinnich’s guillemots on homoya, kharlov, bjemeya and kovalskifjellet, spitsbergen. numbers above columns = no. of fish counted. c. harengus = hemng, m . villosus = capelin, ammodytes sp. = sand eel, g. fubricii = squid, lumpenus sp. = blenny, b. suida = polar cod. -l t ab le 1 . f oo d ite m s in th e di et o f co m m on g ui lle m ot s in th e b ar en ts s ea re co rd ed in th e lit er at ur e. n = n um be rs o f ad ul t s to m ac hs (s ) o r c hi ck f oo d ite m s (f ) s am pl ed . n um be r af te r a s to m ac h fo od i te m = n o. o f st om ac hs c on ta in in g th at f oo d ite m . ? = s am pl e si ze n ot g iv en . $ % d ur in g br ee di ng s ea so n in o r ne ar c ol on ie s n ov ja z em lj a d at e n f oo d it em s 19 47 1 3 s po la r co d 13 , a tla nt ic c od 3 . 19 48 -5 0 20 s po la r co d 8, a tla nt ic c od 2 , sa nd e el s 3, c ap el in 2 , s cu lp in 2 . b j@ m @ ya 19 48 19 96 ?f ?s m ai nl y sm al l g ad oi d fi sh m ai nl y eu ph au si id s k ol a p en in su la ( k hn rl ov ) 19 35 46 f a tla nt ic c od , sa nd e el a nd h er ri ng , fi g. 4 . 19 38 19 8f m ai nl y sa nd e el , fi g. 4 . 19 37 -3 9 85 f m ai nl y ca pe lin a nd s an d ee l, fi g. 4 . 19 47 -4 9 19 60 21 s 19 92 9 s 2 4 ,4 7 & 4 1s a tla nt ic c od , sa nd e el a nd h er ri ng , fi g. 4 . g ad oi ds 1 3, c ap el in 5 , c ru st ac ea 3 a nd n er ei s 1. sa nd e el s 5, h er ri ng 2 , a tla nt ic c od i , ca pe lin 1 . n o w a y 19 70 s 19 83 19 84 19 87 ?f 79 f 24 f 1 8 s v ed oy , r gs t. m ai nl y sa ith e an d sa nd e el s, o cc . p ho lis g un ne llu s h je lm sg y. 9 9% c ap el in . h je lm so y. s ai th e 16 , s an d ee l 3, a na rh ic ha s lu pu s 3, s qu id 1 . b le ik sg y. m os tly s qu id b ea ks . o ut si de b re ed in g se as on in c oa st al w at er s a pr 1 98 6 1 7 s e as t fi nn m ar k. e xc lu si ve ly c ap el in . a pr 1 98 5 ? t ro m sa . m os tly c ap el in . so ur ce k an da la ks ha r es er ve a rc hi ve s u sp en sk i 19 56 se rg ea nt 1 95 1 m eh lu m e t al . i n pr es s b el op ol ’s ki i 19 57 k af ta no vs ki 1 93 8 k an da la ks ha r es er ve a rc hi ve s b el op ol ’s ki i 19 57 g er as im ov a (i n k ra sn ov e t al . 19 95 ) k ra sn ov u np ub l. t sc ha nz & b ar th 1 97 8 v ad er e t al . 19 90 t ro m sg m us eu m u np ub l b ar re tt un pu bl . e ri ks ta d & v ad er 1 98 9 v ad er e t al . 19 90 the diets of common and briinnich’s guillemots 77 were fed to chicks in the 1970s (tschanz & barth 1978). in 1938, the only single year for which there is published data for the briinnich’s guillemots on kharlov, sand eels constituted >80% of the diet of both species (kaftanovski 1938). of 20 fish observed in 1994 being fed to briinnich’s guillemot chicks on novaja zemlja by strom et al. (1994), seven were polar cod and four were capelin. on bjernoya, chicks of both guillemot species were fed mainly fish (roi 191 1; duffey & sergeant 1950; sergeant 1951). these were identified as “mainly gadoids” and may well have been polar cod. on kovalskifjellet in 1989, briinnich’s guillemot chick diet consisted almost entirely of polar cod (mehlum & gabrielsen 1993). adult stomach samples most of the data found in the literature were based on stomach samples from adult birds shot or otherwise collected on or near breeding colonies. four other studies were of birds collected in ice covered waters during the summer; another was from the central barents sea and five were from coastal waters during the autumn and spring (tables 1 and 2). the methods of quantification varied considerably among the studies, from near anecdotal notes (e.g. the 19th century references) to detailed estimates of frequencies of occurrence of prey items (e.g. lydersen et al. 1989; erikstad 1990; mehlum et al. 1996; in press) or percentage contribution by mass or energy (weslawski et al. 1994). this prohibited any quantitative compari fig. 4. composition (%) of the diet of common guillemots at seven islands and of briinnich’s guillemots at novaja zemlja in the 1930s and 1940s. data from krasovskii (1937). kaftanovski (1938), uspenski (1956), belopol’skii (1957) and kandalaksha state nature reserve archive. sample sizes are given in table 1. (see fig. 3 text for english names of prey.) sons between sites. certain patterns do, however, arise from the data. there is little data on the common guillemot from novaja zemlja (in bezymyannaya bay), and the main food items documented in the late 1940s were polar cod and atlantic cod gadus morhua (table 1). further west, on kharlov off the kola peninsula, common guillemot stomachs sampled in the late 1930s and 1940s again contained mainly fish (capelin, atlantic cod, herring and sand eels, table 1, krasovskii 1937; kaftanovski 1938; belopol’skii 1957). these data are also summarised in fig. 4. of nine adult stomachs sampled on kharlov in 1992, five contained sand eels, two contained herring, one contained atlan tic cod and one contained capelin (table 1). polar cod and atlantic cod constituted most of the briinnich’s guillemot diet on novaja zemlja in the late 1940s, but other fish such as sand eels, capelin, herring and sculpins were also eaten (table 2, fig. 4) (krasowski 1937; uspenski 1956; belopol’skii 1957). in 1992, 10 of 31 briinnich’s guillemot stomachs sampled on novaja zemlja contained food (table 2). gadoids were found in four, snail fish liparis sp. in two, and capelin, sand eels, sculpins, unidentified fish and crustaceans in one each. in 1993, 12 of 14 briinnich’s guillemot stomachs analysed in franz josef land contained polar cod, four contained crustaceans, one contained polychaetes, and one contained unidentified fish. belopol’skii (1971) otherwise summarises the contents of 11 1 briinnich’s guillemot stomachs sampled on kharlov in 1935, 1941 and 1 9 4 7 4 9 . herring was found in 30, sand eels in 18, atlantic t ab le 2 . f oo d ite m s in th e di et o f b ri in ni ch ’s g ui lle m ot in th e b ar en ts s ea r ec or de d in th e lit er at ur e. r ef er en ce s m ar ke d w ith a n as te ri sk ( *) a re q uo te d fr om l gv en sk io ld ( 19 64 ). n = n um be rs of a du lt st om ac hs ( s) o r ch ic k fo od i te m s (f ) sa m pl ed . n um be r af te r a st om ac h fo od i te m = n o. o f st om ac hs c on ta in in g th at f oo d ite m . ? = s am pl e si ze n ot g iv en . d ur in g br ee di ng s ea so n in o r ne ar c ol on ie s n ov ja z em lja d at e n 19 25 ? ?f 19 34 62 f 19 42 , 4 7 46 , 29 28 19 48 -5 0 44 , 52 1, & 3 12 s 19 92 31 s 19 94 20 f f ra ns j os ef l an d 19 31 16 s 19 91 -9 3 11 s 19 93 14 s sv al ba rd 18 89 ? 18 96 ?f 18 98 ? 18 98 ?s 18 98 , 1 90 0 ? ? ? 19 10 ?s 19 24 ? 19 33 4 s 19 67 49 1 s 19 89 16 1f 19 92 23 s f oo d ite m s po la r co d, g ad oi ds , c ap el in . m ai nl y a tl an ti c co d, f ig . 4. m ai nl y a tl an ti c an d po la r co d, f ig . 4 . v ar ie d: a tl an ti c co d, p ol ar c od , sa nd e el s, f ig . 4. g ad oi ds 4 , sc ul pi ns 2 , a tla nt ic c od 1 , c ap el in 1 , s. e el 1 , l ip ar is 1 , c ru st . 1 po la r co d 7, c ap el in 4 , sa nd e el s 2, b le nn ie s 2. c ru st ac ea ns 8 , u ni d. f is h 7, p ol yc ha et es 2 . 93 % (b y m as s) p ol ar c od , 6 sp p. o f cr us ta ce a, m ai nl y p ar ar he m is to li be llu la . po la r co d 12 , c ru st ac ea ns 4 , p ol yc ha et es 1 a nd u ni d. f is h 1. e dg eg ya . a m ph ip od s, m ai nl y g am m ar us lo cu st a. is fj or de n, p ol ar c od . m id te rh uk en , va n m ije nf jo rd en . po la r co d. a m ph ip od s an d ot he r cr us ta ce a, fi sh . sp its be rg en . c ru st ac ea ns , p ol ar c od , l um pe nu s sp . fi sh . m id te rh uk en , b el ls un d. m ai nl y po la r co d. y ou ng f ed o n fi sh . a lk ef je lle t, h in lo pe n. a du lts a nd y ou ng f ed e xc lu si ve ly o n fi sh . a ll co nt ai ne d t hy sa no es sa in er m is . e dg eg ya . o nl y ga m m ar id s. 84 % p ol ar c od , 10 % l um pe ni da e, 2 % c ot ti da e, 4 % u ni d. f is h. st or fj or de n. p ar at he m is ro s pp ., t. in er m is , g . w ilk its ki i, po la r co d. so ur ce g or bu no v 19 25 in u sp en sk ii 19 56 k ra so vs ki i 19 37 b el op ol ’s ki i 19 57 u sp en sk i 19 56 k ra sn ov 1 99 5 s tr gm e t al . 19 94 d em m e 19 34 w es la w sk i et a l. 19 94 k ra sn ov 1 99 5 w al te r 18 90 * t re vo rb at ty e 18 97 * n at ho rs t 19 00 r om er & s ch au di n 19 00 * k ol th of f 19 03 b ir ul ja 1 91 0* m un st er hj el m 1 91 1 m on ta gu e 19 26 * h ar tle y & f is he r 19 36 de k or te 1 97 2 m eh lu m & g ab ri el se n 19 93 m eh lu m e t a l. 19 96 b j@ m #y a 18 99 ? 19 08 ? 19 48 ? 19 95 , 1 99 6 12 , ? k ol a p en in su la ( k ha rl ov ) 19 38 36 f 19 35 , 1 94 0s 11 1s 19 60 11 s n or w ay 19 83 49 f a du lts a te c ru st ac ea , po ly ch ae te s an d fi sh . y ou ng f ed o n fi sh . y ou ng f ed o n fi sh . c ru st ac ea ns in a du lt st om ac hs . y ou ng f ed c hi ef ly s m al l (c a. 5 0 m m ) ga do id s. o ne s to m ac h co nt ai ne d re m ai ns o f ga do id s & p ol yc ha et es . m ai nl y eu ph au si id s t. in er m is . 86 % s an d ee l, 8% h er ri ng , 3 % g ad oi d, 3 % “ ot he r” . h er ri ng 3 0, s an d ee ls 1 8, g ad oi d 16 , c ap el in 1 4, c ru st ac ea ns 5 c ap el in 5 , g ad oi d 5, s eb as te s 1. h je lm sg y. 3 3% c ap el in , 2 4% s qu id , 2 2% s an d ee l. d ur in g br ee di ng s ea so n in o pe n w at ed ic eco ve re d w at er s sv al ba rd 19 85 /8 6 18 s 19 86 16 s 19 82 -8 7 13 s pe la gi c, i ce -c ov er ed w at er s. p ar at he m is to l ib el lu la , p ol ar c od . 19 84 -8 5 12 s k on gs fj or de n. b en th ic a m ph ip od s, p ol ar c od , u ni d. f is h. fi rs t ye ar i ce . m ai nl y p an da lu s bo re al is , a m ph ip od s an d po la r co d. m ul tiye ar i ce . 4 8% f is h, m os tly p ol ar c od . 33 % a m ph ip od s, m os t g . w ilk its ki i. o ut si de b re ed in g se as on in c oa st al a n d o pe n w at er s s ep 1 98 4 21 s s pr in g 19 85 -8 7 7 6 s s pr in g 19 85 14 s h om su nd . t . in er nt is , ga m m ar id s, p ol ar c od . f eb 1 98 7 3 0 s h op en . p . lib el lu la a nd p ol ar c od . m ar 1 98 7 24 s se nt ra lb an ke n. a tla nt ic c od , p ol ar c od a nd c ru st ac ea ns . a pr 1 98 6 28 s e as t fi nn m ar k. e xc lu si ve ly c ap el in . a pr 1 98 5 ?s t ro m sg . m os tly c ap el in . h om su nd . p ol ar c od d om in at ed , f ol lo w ed b y p . lib el lu la a nd p ol la ch iu s vi re ns m ar gi na l ic e zo ne . p . lib el lu la , p ol ar c od , t. in en ni s, p an da lu s bo re al is . s w en an de r 19 00 r oi 1 91 1 d uf fe y & s er ge an t 19 50 m eh lu m e t al . in p re ss k af ta no vs ki 1 93 8 b el op ol ’s ki i 19 71 g er as im ov a in k ra sn ov e t al . 19 95 v ad er e t al . 19 90 l gn ne & g ab ri el se n 19 92 lp cn ne & g ab ri el se n 19 92 m eh lu m & g je rt z 19 84 , g je rt z et a l. 19 85 , m eh lu m & g ab ri el se n 19 93 m eh lu m & g ab ri el se n 19 93 l yd er se n et a l. 19 89 m eh lu m & g ab ri el se n 19 93 m eh lu m & g ab ri el se n 19 93 b ak ke n 19 90 e ri ks ta d 19 90 e ri ks ta d & v ad er 1 98 9 v ad er e t al . 19 90 y z a 3 r d 4 w 80 r. t. barrett et al. cod in 16, capelin in 14 and crustaceans in five (table 2 ) . very little data have been published from any of the huge briinnich’s guillemot colonies on svalbard. adult stomach samples and a few observations of food fed to chicks indicate that polar cod and crustaceans (mainly amphipods) are the most frequent items taken during the breeding season (table 2 ) . however, prior to and after breeding, the diet of briinnich’s guillemots shot in or near the ice edge consisted nearly solely of crustaceans dominated by amphipods parathe misto libellula and gammarus spp. and, in one study, the prawn pandalus borealis (table 2 ) . three studies of adult briinnich’s guillemots at and around bjgrngya (swenander 1900; roi 191 1; mehlum et al. in press) recorded crustaceans, polychaetes and fish among stomach contents. there are also little data from the coast of norway, but it seems that fish again constituted the total diet of both species with capelin comprising 100% of the prey of both species when they gathered off the coast of tromsg and finnmark just before breeding in the mid-1980s (tables 1 & 2). squid beaks dominated the food remains found in 18 stomachs of adults sampled off bleiksgya, vesterailen, in june and july 1987 (barrett unpubl.). the total number of prey taxa recorded in the briinnich’s guillemot diet in the barents sea region is at least 37, including 17 crustaceans, 16 fish, molluscs, polychaetes and squid. thirteen taxa, mostly fish (capelin, herring, sand eel, atlantic cod, polar cod, wolf fish anarhichas sp., butterfish, sculpins (cottidae), saithe and red fish sebastes sp.) but also squid, polychaetes and molluscs have been documented in the common guillemot diet. discussion general comparisons of briinnich’s and common guillemot diets in canada are discussed by tuck (1960) and bradstreet & brown (1985). this paper presents the first such comparison from the barents sea region. as in the canadian studies, briinnich’s guillemots in the barents sea have a diet of fish and crustaceans, many of which are benthic or associated with ice. their diet is also much more varied than that of common guille mots which catch mainly small pelagic, schooling fish. more details concerning the food differences between the two species at horngya and bjgrngya are discussed by barrett et al. (1997), while annual differences in chick diet at horngya and kharlov are discussed in relation to prey avail ability by barrett & krasnov (1996). it is, however, likely that adult birds consume food different from what they feed their chicks. this was found, for example, in gulls (laridae) by nogales et al. (1995) and partly shown for common guillemots on kharlov in 1935 and 1992 by belopol’skii (in kandalaksha state reserve archives) and jvk (table l ) , respec tively. on kharlov, chicks were fed mainly high energy, pelagic and schooling fish (capelin, herring and sand eel) while many adult stomachs also contained more benthic fish such as atlantic cod and other gadoids. similarly, briinnich’s guillemot chicks on kovalskifjellet were mainly fed polar cod in 1992 (fig. 3), while adults shot offshore, near the colony in the same season, had large proportions of amphipods and euphausiids in their stomachs (mehlum et al. 1996). the same pattern was found at bjernaya in 1993 when stomachs of adults shot offshore contained pre dominantly euphausiids thysanoessa inermis (mehlum et al. in press), while chicks were fed mainly capelin and polar cod (fig. 3). a study of both guillemot species in the same area in 1996 showed that euphausiids were also the dominant prey of common guillemots (mehlum et al. in press). the potential for such differences between adult and chick diets, plus the paucity of data of either kind from all parts of the barents sea, seriously restricts the identification of definitive, broad-scale geographic trends. despite this, the data collected along the mainland coasts of norway and russia do suggest that capelin is especially important as guillemot prey in the early spring (march-april). this is the time when huge flocks of both guillemot species gather to feed on the mature, energy-rich capelin as it approaches the finnmark coast to spawn (barrett 1979; erikstad & vader 1989; strann et al. 1991; krasnov 1995; nikolaeva et al. 1996). these flocks consist not only of birds which breed in the barents sea colonies but also of young common guillemots from, for example, british colonies (strann et al. 1991). furthermore, the distribution of guillemots out at sea early in the year (january-march) and in august-september also seems to coincide with the distribution of capelin (fauchald & erikstad 1995; krasnov the diets of common and briinnich’s guillemots 81 unpubl.). this suggests that capelin is an im portant prey for both species in the central and southern barents sea for at least 4-6 months of the year. although the numbers of capelin along the coast drop after the spawning season, there are always some late spawners available to guillemots throughout the summer (barrett & furness 1990; barrett & krasnov 1996). at least half the numbers of capelin fed to common guillemot chicks on hornpya during seven breeding seasons in the 1980s and 1990s were gravid females (barrett unpubl.). that fewer capelin are taken at kharlov reflects the fact that while capelin almost always occur and spawn in east finnmark, their movements along the kola peninsula are limited to the years when large influxes of warm atlantic water spread further east than normal (ozhigin & luka 1984; gjpszter et al. 1994). similarly, when herring stocks are at their iowest (as was the case in the early 1980s), the youngest year classes of herring do not spread as far east along the coast as they do when the stocks are large (dragesund et al. 1980). such variations in stock levels explain the near absence of herring in the hornpya samples before 1985 and the subsequent increase in the 1990s (fig. 2) and the differences in the amount of herring caught by guillemots on kharlov and hornpya (barrett & krasnov 1996). unfortunately little is known about the distri bution of sand eels in the southern barents sea, but there are spawning grounds around kharlov which are large enough to support a periodic local fishery (krasnov & barrett 1995) and hence contribute to the predominance of sand eels in the local guillemot chick diet (figs. 2 and 3). the data from the literature also document the importance of crustaceans in the diet of adult briinnich’s guillemots around spitsbergen and franz josef land. the dominance of crustaceans in the diet is especially true of birds sampled at sea around spitsbergen during the late winter, spring and summer. food samples in five of ten studies were dominated by the large hyperiid amphipod parathemisto libellula, three by other crustaceans (amphipods or euphausiids) and only two by fish (polar cod). among the 14 studies of birds collected in or near colonies around spitsbergen and franz josef land, seven recorded crustaceans as the main prey type (table 2). among the crustaceans listed are the amphi pods p . libellula and gammarus wilkitskii which are often associated with waters near or covered by ice (sakshaug et al. 1994) and which are much more abundant than, for example, polar cod. although of poorer quality energetically (gabrielsen et al. 1994; gabrielsen pers. comm.), these amhipods are more widely spread, probably more accessible, and thus taken in preference to solitary fish hiding in the ice or on the sea bottom. however, because guillemots chicks are fed food items brought to them singly, the adults probably seek out the larger fish to make the transport into the colony energetically worthwhile. this would explain the high proportion of polar cod in the diet of chicks at kovalskifjellet compared to the crustacean-rich diet of the adults collected off shore in 1992. despite the differences in chick and adult diets, geographical variation in the species of fish caught is apparent from our data and those found in the literature. polar cod is an important prey in svalbard, franz josef land and novaja zemlja but not along the coasts of norway and the kola peninsula where capelin, sand eel and herring dominate. the restriction of polar cod to the colder northern and eastern localities stems from the relatively limited distribution of the species’ spawning grounds. the main spawning ground in the southeast comer of the barents sea, between kolguyev and novaja zemlja, and a smaller one is located east of spitsbergen (gjpszter et al. 1994). adult polar cod are spread over much of the barents sea during the summer and are thus taken in very small proportions by guillemots on bjprnpya where there are otherwise more acces sible stocks of capelin. the main bulk of the polar cod population avoids the southwestern areas which is influenced by the inflow of warm atlantic water (gjpszter et al. 1994). other fish recorded in the literature and in our studies in the high arctic waters included benthic species of blennies (lumpenidae or stichaeidae), sculpins and eelpouts (zoarcidae). the absence of these species in the more southern samples probably reflects the more northerly distribution of some of the species, e.g. lumpenus sp., as much as the relative shallowness of the water (enabling the guillemots to reach the benthic species) in the northern areas where guillemots were sampled. the occurrence of the squid gonatus fabricii in the diets of guillemots on bjprnoya and bleiks@y reflects the proximity of these colonies to the main flow of atlantic water in the norwegian and barents seas with which this species is often associated (wiborg 1979). 82 r. t. barrett et al. ecosystem effects of the ca. 1.6 million pairs of briinnich’s guillemots which bred in the barents sea in 1986, ca. 405,000 pairs bred on the southeastern coasts of svalbard (excluding bjomoya) and 1 million pairs on novaja zemlja. furthermore, 245,000 of the total of 266,000 pairs of common guillemots bred on bjornoya together with ca. 100,000 pairs of briinnich’s guillemot (mehlum & gabrielsen 1995). in other words, ca. 25% of the guillemot food consumption during the breeding season in the barents sea in the mid 1980s took place around svalbard, ca. 50% near novaja zemlja, ca. 20% around bjornaya and ca. 5% along the coast of north norway and the kola peninsula. the annual food requirements of both guillemot species in the barents sea is approximately 70% of t h e t o t a l s e a b i r d r e q u i r e m e n t s : i.e., 70% x 3500 tj (1 tj = 10l2 joules) = 2450 tj (sakshaug et al. 1994; mehlum & gabrielsen 1995). if all the guillemots preyed on one or two fish species only, for example, capelin or polar cod, their annual harvest would have had a significant impact on these single prey popula tions, especially in years when the fish stocks were at a minimum. for example, when the capelin stocks plummeted to <0.5 million tonnes in 1986/87, their annual production was in the order of 1-2000tj only (sakshaug et al. 1994). the same would have applied to the polar cod when stocks were at a minimum in e.g. the early 1970s and early 1980s (gjosater 1995). however, this paper has shown that the guillemot diet constitutes many species and varies considerably both spatially (svalbard; mainly crustaceans, novaja zemlja; polar and atlantic cod, bjorngya; euphausiids, capelin and periodically squid, nor way and the kola peninsula; capelin, sand eels, herring and atlantic cod) and temporally. guille mots also take prey items from the lower trophic levels where annual production is an order of magnitude higher (sakshaug et al. 1994). as a result, the overall impact of the guillemot population on the barents sea ecosystem is very slight compared to the annual production at the different trophic levels and of the different fish populations (sakshaug et al. 1994). furthermore, estimates of the annual food requirements of the top predators in the barents sea (atlantic cod, seals, whales and seabirds) by sakshaug et al. (1994) show that the total seabird harvest is equivalent to only ca. 7% of the total food requirements of higher predators in the barents sea, or to ca. 25% of the average annual capelin fishery outtake in the early 1980s (sakshaug et al. 1994). on the other hand, the impact of the ecosystem on the guillemots can be great. this was illustrated in 1986/87 when the collapse in the capelin stocks resulted in huge declines in the breeding populations of common guillemots on bjomoya, in finnmark, and on the kola peninsula (vader et al. 1990; krasnov & barrett 1995). more dietary data are needed before a full assessment can be made and a prey-consumption model for these species in the barents sea can be developed. this applies especially to the region around novaja zemlja where huge numbers of guillemots breed but where their diet is poorly documented. further comparisons of chick and adult diets should also be made in the various regions to test if the documentation of chick diet (which involves a non-destructive method) can also be used to monitor adult food consumption during the breeding season. finally, most data have, up to now, been collected during the summer and very little is known about the diet of guillemots at other times of the year. there is a need for systematic collection of birds from different parts of the barents sea and at different times of the year, especially from areas where large numbers are known to spend at least part of the autumn and winter (fauchald & erikstad 1995; krasnov unpubl.). acknowledgements. parts of this study were financed by the norwegian polar institute, the norwegian research council, tromsp, museum. the university of tromsp, and the kandalak sha state nature reserve. we are grateful to numerous field assistants and to w. vader, g. w. gabrielsen, f. mehlum and two referees for their constructive comments and criticisms of earlier drafts of this paper. references bakken, v. 1990: the distribution and die1 movements of btiinnich’s guillemots uria lomvia in ice covered waters in the barents sea, februarymarch 1987. polar r e x 8, 55-59. bamett, r . t. 1979: small oil spill kills 10-20,000 seabirds in north norway. mar. poll. bull. 10. 253-255. barrett, r. t., asheim, m. & bakken, v. 1997: ecological relationships between two sympatric congeneric species, common and thick-billed murres, uria aalge and (1. loniviu, breeding in the barents sea. can. j . zoo/. 75, 61 8-63 1. the diets of common and bdnnich’s guillemots 83 barrett, r. t. & furness, r. w. 1990: the prey and diving depths of seabirds on homdy, north norway after a decrease i n the barents sea capelin stocks. ornis scand. 21, 179-186. barrett, r. t. & krasnov, y. v. 1996: recent responses to changes in stocks of prey species by seabirds breeding in the southern barents sea. ices j. mar. sci. 53, 713-722. belopol’skii. l. 0. 1957: ecology of sea colony birds of the barents sea. israel progr. for scientific translations, jerusalem. 346 pp. (translated from russian, 1961). belopol’skii, l. 0. 1971: sostav kormov morskikh ptits barentseva moqa (the diet of barents sea seabirds). uchenye zapiski kaliningradskogo gos. universiteta, kali ningrad 6, 41-67. birulja, a. 1910: zoologiceskie reul’taty russkich 2kspedicij na spicbergen: biologiceskija nabludenija nad pticanii spicbergena. annu. mus. zool. acad. 15. st. petersbourg. bradstreet, m. s. w. &brown, r. g. b. 1985: feeding ecology of the atlantic alcidae. pp. 263-318 in nettleship, d. n. & birkhead, t. r. (eds.): the atlantic alcidae. academic press, london. de korte, j. 1972: birds, observed and collected by the “de nederlandse spitsbergen expeditie” in west and east spitsbergen, 1967 and 196849; third and last part. beaufortia 20, 23-58. d e m e , n. p. 1934: ptichii bazar na skale rubini (ostrov gukera, zemlya frantsa iosifa) (bird nesting colony on the cliff ledge of rubini island (hooker island, franz josef land). trudy arkticheskogo institutu 11, 55-86. dragesund, 0.. hamre, .i. & ulltang, 0. 1980: biology and population dynamics of the norwegian spring-spawning hemng. rapp. p.-v. rlun. cons. int. explor. mer. 177, 43-71, duffey, e. & sergeant, d. e. 1950 field notes on the birds of bear island. ibis 92, 5 5 4 4 6 3 . erikstad, k. e. 1990 winter diets of four seabird species in the barents sea after a crash in the capelin stock. polar b i d . 10, 6 19-627. erikstad, k. e. & vader, w. 1989: capelin selection by common and briinnich’s guillemots during the prelaying season. ornis scand. 20, 151-155. fauchald, p. & erikstad, k. e. 1995: the predictability of the spatial distribution of guillemots (uria spp.) in the barents sea. pp. 105-122 in isaksen, k. & bakken, v. (eds.): seabird populations in the northern barents sea. norsk polarinst. medd. 15. oslo. gabrielsen, g. w., ryg, m., mehlum, f., markussen, n. m. & ehitsland, n. a. 1994: sjbfugl og sjbpattedyr. pp. 203-221 in sakshaug, e., bjbrge, a,, gulliksen, b., loeng, h. & mehlum, f. (eds.): 0kosystem barentshavet. norges forsk ningsrld, univ.forlaget, oslo. gjertz, i., mehlum, f. & gabrielsen, g. w. 1985: food sample analysis of seabirds collected during the “lance”-cruise i n ice-filled waters in eastern svalbard 1984. norsk polar insf. rapp. ser. no. 23, 1-17. gjbsaeter, h. 1995: pelagic fish and the ecological impact of the modern fishing industry in the barents sea. arctic 48, 267-278. gjdsaeter, h., godd, 0. r. & ulltang, 0. 1994: de viktigste fiskeslagene i barentshavet. pp. 181-202 in sakshaug, e., bjdrge, a., gulliksen, b., loeng, h. & mehlum, f. (eds.): 0kosystem barentshavet. norges forskningsrld, univ.forla get, oslo. gorbunov, g. p. 1925: ptich’i bazary novoi zemli (cliff-ledge nesting colonies of birds on novaja zemlja). trudy nauchno issledovatel’skogo instituta p o izucheniyu severa 26, 1 4 7 . hartley, c. h. & fisher, j. 1936: the marine foods of birds in an inland fjord region in west spitsbergen. j . anim. ecol. 5 , 37g389. kaftanovski, y. m. 1938: kolonial’noe gnezdov’e kair i faktory vyzyvayushchie gibel’ yaits i ptentsov (colony nesting of the murre and factors causing the death of the eggs and nestlings). zoologicheskii zhurnali7, 695-705. kolthoff, g. 1903: bidrag ti1 k h e d o m om norra polamakter nas daggdjur och foglar. kgl. sv. vet. akad. handl. 36. stockholm. 104 pp. krasnov. y. v. 1995: ekologiya i povedenie morskikh ptits nu sovremennom etape expluatatsii resursov barentseva niorj (the ecology and behaviour of seabirds during the recent stage of exploitation of barents sea resources). dissertatsia na soiskanie uchenoi stepeni doktora biologicheskikh nauk. 369 pp. krasnov, y. v. & barrett, r. t. 1995: large-scale interactions among seabirds, their prey and humans in the southern barents sea. pp. 443-456 in skjoldal, h. r., hopkins, c., erikstad, k. e. & leinaas, h. p. (eds.): ecology of fjords and coastal waters. elsevier science b.v., amsterdam. krasnov, y. v., matishov, g. g., galaktionov, k. v. & savinova, t. n. 1995: morskie kolonial’nye ptitsy murmana ( m m a n ’ s colonial seabirds). st. petersburg “nauka” publ. 224 pp. (in russian). krasovskii, s. k. 1937: etyudy po biologii tolstoklyuvoi kairy (studies of the biology of the thick-billed murre). trudy arkticheskogo instituta, biologiya 7 7 , 32-92. lydersen, c., gjertz, i. & weslawski, j. m. 1989: stomach contents of autumn-feeding vertebrates from hornsund, svalbard. polar rec. 25, 107-1 14. ldnne, 0. j . & gabrielsen, g. w. 1992: summer diet of seabirds feeding i n sea-ice-covered waters near svalbard. polar biol. 1 2 . 685-692. lbvenskiold, h. l. 1964: avifauna svalbardensis. norsk polarinst. skr. no. 129, 1 4 5 5 . mehlum, f. & gabrielsen, g. w. 1993: the diet of high-arctic seabirds i n coastal and ice-covered, pelagic areas near the svalbard archipelago. polar res. 12, 1-20. mehlum, f. & gabrielsen, g. w. 1995: energy expenditure and food consumption by seabird populations in the barents sea region. pp. 4 5 7 4 7 0 in skjoldal, h. r., hopkins, c., erikstad, k. e. & leinaas, h. p. (eds.): ecology of fjords and coastal waters. elsevier science b.v., amsterdam. mehlum, f. & gjertz, i. 1984: feeding ecology of seabirds in the svalbard area a preliminary report. n o w . polar inst. rapp. ser. no. 16. 1 4 1 . mehlum, f., hunt. g. l., klusek, z., decker, m. b. & nordlund. n. 1996: the importance of aggregations to the distribution of briinnich’s guillemots in storfjorden, svalbard. polar biol. 16, 537-547. mehlum, f., nordlund, n. & isaksen, k. in press: the importance of the polar front as a foraging habitat for guillemots uria spp. breeding at bjbrnbya, barents sea. j . mar. systems. montague, f. a. 1926: notes from spitsbergen. ibis 68, 136151. munsterhjelm, l. 191 1: beobachtungen w&end einer ornitho logischen studiereise nach dem nordpolmeer und spitz bergen im sommer 1910. ofversikf af finska vet.-soc. f6rh. ed. 53, afd. a, no. 20, 1 4 2 . 84 r. t. barrett et al. nathorst, a. g. 1900: tvas somrar i ishafet. vul. 1 . stockholm. 352 pp. nikolaeva, n. g., krasnov, y. v. & barrett, r. t. 1996. movements of common uria aalge and briinnich’s guillemots u. lomvia breeding in the southern barents sea. fauna now. ser. c, cinclus 19, 9-20. nogales, m., zonfrillo, b. & monaghan, p. 1995: diets of adult and chick herring gulls larus argentatus on ailsa craig, south-west scotland. seabird 17, 56-63. ozhigin, v. k. & luka, g. i. 1984: some peculiarities of capelin migrations depending on thermal conditions in the barents sea. pp. 135-147 in gjweter, h. (ed.): pruc. sov. now. symp. on barents sea capelin, bergen. roi, 0. le 1911: spezieller teil. in koenig, k. (ed.): avifauna spitzbergensis. furschungreisen nach der baren-insel und dem spitzbergen-archipel, mit ihrem faunistischen und floristischen ergebnisse. bonn. 294 pp. romer, f. & schaudin, f. 1900 fauna arctica. bd. 1. jena. sakshaug, e., bjorge, a., gulliksen, b., loeng, h. & mehlum, f. 1994 structure, biomass distribution, and energetics of the pelagic ecosystem in the barents sea: a synopsis. polar biol. 14, 405411. sergeant, d. e. 1951: ecological relationships of the guillemots uria aalge and uria lomvia. pruc. x int. om. congr. (uppsala, 1950). 578-587. strann, k.-b., vader, w. & barrett, r. t. 1991: auk mortality in fishing nets in north norway. seabird 13, 22-29. strcim, h., (zliene, i. j., opheim, j., kuznetsov, e. a. & khakhin, g. v. 1994: seabird censuses on novaya zemlya 1994. nof rapportserie, rupp. nr. 2-1994, 1-38. swenander, g. 1900 beitrage zur fauna der b a e n insel. bihang till kgl. sv. vet. akad. bihang 26. afd. iv, 1-50. trevor-battye, a. 1897: the birds of spitsbergen, as at present determined. ibis 39, 574-600. tschanz, b. & barth, e. k. 1978: svingninger i lomvibestanden p i vedoy p i rost. fauna 31, 205-219. tuck, l. m. 1960: the murres: their distribution, populations and biology a study of the genus uria. can. wildlife munogr. ser. no. 1, ottawa. 260 pp. uspenski, s. m. 1956 the bird bazaars of novuya zemlya. cws translation of russian game reports, vol. 4, ottawa. 159 pp. (translated from russian, 1958). vader, w., barrett, r. t., erikstad, k. e. & strann, k.-b. 1990 differential responses of common and thick-billed mums to a crash in the capelin stock in the southern barents sea. stud. avian biol. 14, 175-180. walter, a. 1890 omithologische ergebnisse der von der bremer geographischer gesellschaft im jahre 1889 veran staltete reise nach ostspitzbergen. j. om. 38. weslawski, j. m., stempniewicz, l. & galaktionov, k. 1994: summer diet of seabirds from the frans josef land archipelago, russian arctic. polar res. 13, 173-181. wiborg, k. f. 1979: gunatusfabricii (lichtenstein), en mulig fiskeriressurs i norskehavet. fisken hav. 1979 ( 1 ) . 3 3 4 6 . past and present permafrost as an indicator of climate change hugh m. french the permafrost history of the high northern latitudes over the last two million years indicates that perennially frozen ground formed and thawed repeatedly, probably in close synchronicity with the climate changes that led to the expansion and subsequent shrinkage of continental ice sheets. the early stages of the pleistocene are the least known and the changes that occurred in the late pleistocene and early holocene are the best known. evidence that permafrost is degrading in response to the current global warming trend is difficult to ascertain. the clearest signals are probably provided by changes in permafrost distribution in the sub-arctic regions. at the extreme southern fringes of the discontinuous permafrost zone. h . m . french, depts. of geography and earth science, universit?, of ottawa, p.o. box 450, station a , ottawa. ontario kin 6n5, canada. introduction past permafrost at high latitudes today, permafrost forms under current climatic conditions. a map recently compiled and published under the auspices of the international permafrost association (brown et al. 1998) indicates that permafrost occupies approximately 20-25% of the earth's land surface in the northern hemisphere. in the case of the north american continent, field observations i n both canada (e.g. brown 1967; national atlas of canada 1995) and alaska (e.g. ferrians 1994) indicate that the southern limit of continuous permafrost coincides with the general position of the -6 to -8°c mean annual air temperature (maat) isotherm. this relates to a ground temperature of about -5°c measured just beneath the depth at which seasonal fluctuations are minimal. the discontinuous permafrost zone lies to the south of the continuous zone. its southern limit approximates the 1 "c maat isotherm and ground temperatures vary from just below 0°c to -3 or -4°c. the most extreme, or southern, occurrences of permafrost are found beneath peaty materials, the result of the unusual insulating properties of such material. permafrost has undergone growth and decay at various times during earth's history. there is convincing evidence to suggest that much of today's permafrost probably originated during the fluctuating climate of the pleistocene. some of the most striking evidence includes the remains of woolly mammoths and other pleistocene animals found preserved i n permafrost in siberia, alaska and north-western arctic canada. another line of evidence is cryostratigraphic: i n some areas, the upper boundary of permafrost lies below the depth of modem seasonal freezing and the temperature of permafrost sometimes decreases with increasing depth. both phenomena indicate residual (i.e. relict) cold. another clue lies in the fact that the thickest permafrost occurs in areas which escaped glaciation and which were not protected from cold subaerial conditions by a thick ice cover. finally, offshore or submarine perma frost exists on the continental shelves beneath both the kara and beaufort seas and could only have formed when sea level was lower (i.e. during the cold periods of the pleistocene). cryostratigraphic evidence for pleistocene-age french 1999: polar research 18(2), 269-274 269 palaeo active layer active layer thaw relict active layer unconformity palaeo-thaw uncontorrni t y seasonally frozen layer fig. i . diagram illustrating the types of ice discontinuities commonly found within perennially frozen sediments in (a) the continuous permafrost zone of the arctic. or the tundra region, and (b) the discontinuous permafrost zone of the sub-arctic region. residual thaw layer palaeo-thaw unconformity permafrost v v [71 t 1 o’c (seasona//y [71 t ~ o o c (unfrozen thawed ground) . . ground) t ~ c (seasonally frozen ground) t< o’c (perennially frozen ground) permafrost is provided by the study of the ice discontinuities (e.g. murton & french 1994; french 1998) commonly found within perennially frozen sediments. most permafrost, especially that which has formed in unconsolidated sediments, contains ice. this may be as much as 30-50% by volume in the upper few metres. discontinuities in the ice are usually the result of either the thaw of frozen material or the subsequent refreezing of previously thawed materials. the significance of these discontinuities, termed “thaw unconformi ties.” are explained below. figure 1 shows the typical permafrost condi tions which might exist in (a) the continuous permafrost zone of the arctic, or the tundra region, and (b) the discontinuous permafrost zone of the sub-arctic, or the boreal forest (taiga) region. i n (a), the “active layer” is shown as the surficial horizon of permafrost terrain which thaws during the summer months. a “relict active layer” is shown as ground immediately below the modem active layer that was once part of the active layer but which is now perennially frozen. a “palaeo active layer” is shown as the horizon between the ground surface and the base of the relict active layer. in (b), a “residual thaw layer” is shown as referring to an unfrozen layer, formerly perma frost, lying between the modem depth of seasonal frost penetration and an underlying permafrost body. the base of the current active layer, as in (a), is the simplest and most obvious example of a thaw unconformity . from the viewpoint of permafrost history, it is possible to distinguish between primary (i.e. present-day) and secondary (i.e. palaeo-) thaw unconformities. both are shown in (a), but i n (b) a palaeo-thaw unconformity overlies permafrost unrelated to the present surface conditions. as such, the permafrost is “relict.” the manner in which permafrost degrades and subsequently reforms, and the cryostratigraphic evidence which it leaves, is illustrated i n fig. 2 , which considers a scenario of permafrost terrain being subject to warming and subsequent cooling. it depicts an initial permafrost sequence (a), that is subject to degradation from the surface down wards, possibly the result of regional climate warming (b). as thaw proceeds, a primary thaw unconformity (t-ul) forms at depth below a residual thaw layer. at this time, the ground surface experiences only seasonal freezing and thawing. in the process, an ice wedge is truncated and is no longer active. when the climate subsequently deteriorates, as in (c), permafrost aggrades and the base of the active layer again becomes the primary thaw unconformity. re newed thermal contraction cracking at the ground surface permits a new ice wedge to form. during this process, the original thaw unconformity at depth becomes a secondary (i.e. palaeo-) thaw unconformity (t-u2). the latter can be recognized 210 past and present permafrost as an indicator of climate change f i g . 2. diagram illustrating the cryoatmigraphic evidence associated with the degradation and subsequent aggradation of permafrost. (a) an initial pennafrost sequence is (b) subjected to degradation from the surface downwards. possibly the result of regional climate warming. as thaw proceeds, a primary thaw unconformity (t-u 1) forms at depth below a residual thaw layer. i c ) when the climate suhsequently deteriorates, permafrost apgrades and the base of the active layer again becomes the primary thaw unconformity. a layer 7 t u -' 0 ". i"' ice wedge permafrost lenticular cryostructure permafrost reticulate cryostructure by both the truncated ice wedge and by different ice structures (cryostructures) in the sediments above and below. using this kind of evidence, russian geogra phers (e.g. gerasimov & velichko 1987,; rozen baum & shpolyanskaya 1998) have undertaken large-scale palaeo-environmental reconstructions for the last two million years. for europe and northern eurasia they suggest four stages of permafrost evolution, the earliest being the least known. during the earliest stage, between approxi mately 2.0-0.7 mya. permafrost probably existed without interruption throughout much of yakutia and north-eastern siberia. by contrast. in northern europe. western siberia and mainland north america, permafrost probably formed and thawed on several occasions, but little is known of these conditions. between approximately 190 kya and 10 kya. extensive regions dominated by permafrost con ditions existed once again in both eurasia and north america to the south of the late pleistocene ice sheets. isotopic data (klimenko et al. 1996) indicate that global air temperatures probably dropped by as much as 4 ' c on several occasions during the last 223 ky. this was sufficient to cause significant expansion of areas underlain by permafrost at about 150 kya, 70 kya and 25 kya. one example of all these changes is found near fairbanks in central alaska. there, the eva forest bed (pcwc et al. 1997) lies buried within frozen loess-like materials. the organic remains indicate that the last interglaciation of the north american continent, about 12.5 000 years ago, was a major warm period when there was erosion of loess and the deep and rapid thawing of previously formed permafrost. during the l 0 0 k y that followed, a treeless steppe-like tundra environment returned to northern alaska and the deposits were refrozen as permafrost once again developed. in this time period, permafrost attained its greatest thickness and its lowest temperature in those high-latitude areas of the northern hemi sphere that escaped glaciation. thicknesses in excess of 500 m formed with temperatures at the depth of zero annual amplitude of greater than i s -c. in addition, and in response to the lower sea level in the arctic basin, the continental shelves of the beaufort and kara seas, together with the bering strait, were exposed to perma frost forming, cold-climate subaerial conditions. at this time, the extreme maximum southern limits of permafrost probably extended as far south as 50" in european russia and kazakh stan. during the holocene, or the last 10 ky, there is evidence to indicate that the climate ameliorated, causing permafrost to partially thaw but to then subsequently refreeze towards the end of the holocene. these conditions can be demonstrated with reference to the lowlands of the western canadian arctic. there, observations indicate the existence of a thick palaeo-thaw layer (see e.g. burn 1988, 1997; harry et al. 1988; murton & french 1994). it occurs at a depth of 125-1socm french 1999: pokir reseurch 18(2). 269-274 27 1 in the tuktoyaktuk region and can be recognized by distinct cryostructural contrasts and, in places, by truncated ice bodies. a good example is from the cliffs at crumbling point, in the pleistocene mackenzie delta (fig. 3). recent years have exposed a massive icy body penetrated by remarkably large inactive sand wedges and large active ice wedges, and overlain by sand and diamicton. radiocarbon dates from here and elsewhere in north-western arctic canada suggest that the active layer was deepest about 8.0-9.0 kya and that it was approximately 2.5 times thicker than the present active layer. a similar early holocene thaw unconformity can be recognized on eastern melville island, at 77"n, at a depth of approximately 113 cm (french et al. 1986). permafrost and past climate the early holocene thaw unconformity in the western canadian arctic can be used to illustrate the relationship between permafrost and inferred past climate. bum (1997) has shown that, with care, i t is possible to make inferences about the palaeo-climate prevailing at this time of maximum thaw. he stresses that certain assumptions are critical to the analysis. one must assume that (a) any increase in the active layer is the result of summer thaw, and (b) that the thawing of frozen ground is linked to the thawing index of degree fig. 3. perennially frozen sediments exposed at crumbling point. pleistocene mackenzie delta. western canadian arctic. the early holocene thaw unconformity truncates icy sediments penetrated by sand wedges. photo by j . b. murton. days above 0°c. using such assumptions, the stefan solution can be used to predict the depth of thaw (see e.g. mackay 1995; burn 1997). accord ing to the stefan solution, a doubling of active layer thickness corresponds to a fourfold increase in thawing index, and an active layer 2.5 times as thick as today implies an increase in the thawing factor by 6.25. this analysis can be applied to the climatic records obtained from the five settlements of whitehorse, inuvik, tuktoyaktuk, sachs harbour and rae point, the latter being an oil company logistics base on eastern melville island (table 1). these localities typically record thawing indices today of 1900,1200,800,400 and 300 degree-days per year, respectively. the current active layer at each locality is approximately 150 cm, 100 cm, 50 cm and 30-25 cm, respectively. these data reflect the progressively shorter and cooler summers with increasing latitude. the current treeline is located just north of inuvik and south of the arctic coast. however, during the early holocene climatic optimum, trees probably ex isted at the location of the present arctic coast. therefore, the most appropriate thawing-index comparison for the present arctic coast (i.e. tuktoyaktuk) is with inuvik. the stefan solution for the maximum depth of the thaw unconformity observed at tuktoyaktuk indicates a thawing index of about 1.5 times current conditions at inuvik; in other words, approximately 1800 thawing degree days. thus, permafrost considerations enable one to conclude that, in the early holocene, the 272 past and present permafrost as an indicator of climate change tuhk i. data showing average active layer depths, the depth of the early holocene thaw unconformity (where recognized), typical annual thawing degree-days, and bio-climatic zonations for s localities i n the western and high arctic of canada (sources: french et al. 1986; bum 1998). thawing active early holocene thaw locality latitude degree-day.; ( c‘) layer (cm) unconformity ecozone whitehorse 6 i ~ ‘ n i900 125-1so boreal forest inuvik 68‘n i200 100 tree1 i ne tuktoyaktuk 69’” 800 so 125-150* tundra sachq harbour i 2 n 400 30-50 eastern melville island 77”n 300 25-so 113** polar semi-desert stefan solution: z = bi 1/2 where l = depth of thaw ( c m ) b = soil thermal properties 1 =thawing degree-daya (-0 t h a w unconformity at 125-150 cm depth corresponds t o npprox. 1800 thawing degree-days. **thaw unconformity at 113 cm depth corresponds to approx. 600 thawing degree-days. summer climate at the location of the present arctic coast was typical of that which exists today near whitehorse, i n central yukon. likewise. the thaw unconformity that can be observed at a depth of 113 cm on eastern melville island corresponds to approximately 600 thawing degree-days; that is, a value typical of the climate that forms the low arctic tundra i n the southern beaufort sea region (i.e. between tuktoyaktuk and sachs harbour). by restricting the depth of snow on the ground in winter, it enhances winter frost penetration. subtle variations in surface vegetation characteristics can also produce significant permafrost changes. as illustrated by the permafrost degradation that follows upon forest fires (e.g. mackay 1995; bum 1998). therefore, if climate warming is occurring, the marginal permafrost present at the extreme southern fringes of the discontinuous zone appears to be especially sensitive. permafrost and climate change conclusions today. clear evidence that permafrost is degrading in response to current global climate change is limited. more time is required before definite trends can be detected. possible indicators of climate warming i n the permafrost regions of northern latitudes are summarized by maxwell (1997). they include: (a) increases i n the thickness of the active layer; (b) increases in the frequency of occurrence of active layer failures and slope instability; and (c) increased thermokarst activity, especially related to an increased frequency of forest fires in the summer in the boreal forest and taiga. in addition to these parameters, however, the history of permafrost over the last two million years suggests that permafrost has grown and decayed in response to global climate change. the techniques of cryostratigraphy can be used to infer past climate changes from the permafrost record. if global climate warming is occumng today, and once the buffering thermal effect of the active layer has been overcome, marginal permafrost bodies located at the extreme southern fringes of the discontinuous permafrost zone will be the first to disappear. probably one of the signals will be acknow&-dgernenrs. -research in northern canada over the last 30 years has been supported by the following branches of the provided by changes i n permafrost distribution in canadian federal government: the natural sciences and the sub-arctic regions, at the extreme southern engineering research council (nserc); the geological fringes of the discontinuous permafrost zone. i n such areas the permafrost is typically less than 1 to -20c’ there’ in addition to the influence of peat bodies, the boreal forest to maintain permafrost in marginal situations since, survey of canada and the polar continental shelf project (both of natural resources canada); and the department of indian and northem affairs. the research has also been supported by the aurora institute of the n.w.t. (formerly the lnuvik research centre) at inuvik. the arctic petroleum operators association (apoa), and the university of ottawa. french 1999: polar research 18(2), 269-274 213 references gerasimov, 1. p. & velichko, a. a. (eds.) 1982: palaeogeo graphy of europe during the last one hundred thousand years. 155 pp. moscow: institute of geography. academy of sciences of the u.s.s.r. harry. d. g.. french, h. m. & pollard, w. h. 1988: massive ground ice and ice-cored terrain near sabine point. yukon coastal plain. can. j . earth sci. 25, 184&-1856. klimenko, v. v., klimanov, v. a,. kozharinov, a. v. & fyodorov, m. v. 1996: global climate and the thousand year temperature trend during the postglncial epoch and holocene. mrteorol. hydro/. 7, 2c-35. mackay, j . r. 1995: active layer changes (1968-1993) following the forest-tundra fire near inuvik. n.w.t.. canada. arct. alp. res. 27, 323-336. maxwell. b. 1997: resportdir~g 10 global climarr change in cunuda's arctic. the canadu c o u n t n study: clirnute iinpacts and adaptation. vol. 11. 8 2 pp. downsview, ontario: atmospheric environment service. environment canada. murton. j . b . & french, h. m. 1994: cryostntctures i n permafrost. tuktoyaktuk coaqtlands, western arctic canada. can. j . earth sci. 31, 737-747. national atlas of canada 1995: permafrost. map mcr 3177f. scale: 1 : 7.500.000. ottawa: natural resources canada. piwe, t . l.. berger. g. w.. westgate. j . a., brown, p. m. r: leavitt. s. w. 1997: eva interglaciatiott forest bed, ringluciuted east-central alaska: global ~~'artnitig 125.000 y a r r ago. geologiccil so&& of america, spccicil publica tion 319. 54 pp. rozenbaum, g. & shpolyanskaya, n. 199x: late cenozoic permafrost history of the arctic. perintifrost and prri,q/ucictl process. 9. 247-274. brown. j . , ferrians, 0. j . , heginbottom. j. a. & melnikov, e. s. 1998: circum-arctic map qf permafrost and ground-ic.e conditions. scale: 1 : 10,000.000. circum-pacific map srrirs. cp-45. washington. d.c.: united states geological survey. brown. r . i. e. 1967: permafrost in canada. map 126ja. ottawa: geological survey of canadmational research council of canada. burn, c. r. 1988: the development of near-surface ground ice during the holocene at mayo. j . quat. sci. 3. 31-38. bum, c. r. 1997: cryostratigraphy, paleogeography. and climate change during the early holocene warm interval, weatern arctic coast, canada. can. j . earth sci. 34, 9 12-925. bum. c. r. 1998: the response (1958-1997) of permafrost and near-surface ground temperatures to forest fires. takhini river valley, southern yukon territory. can. j . earth sci. 35, 184-199. ferrians, 0. j . , jr. 1994: permafrost in alaska. i n g. plaafker & h. c. berg (eds.): the geolo,qy i f alaska. the geology i f north america. vol. g i . pp. 845-851. boulder, co: geological society of america. french. h. m. 1998: an appraisal of cryoatratigraphy in north west arctic canada. perniafrost and perigluciul process. (1. 291-311. french. h. m.. bennett. l. & hayley, d. w. 1986. ground ice investigation\ near rae point and on sahine peninsula, eastern melville ialand. can. j . eurth sci. 23. 13x9-1400. past a n d present permafrost as an indicator o f c l i m a t e c h a n g e investigation of babesia sp. in pygoscelid penguins at the south shetland islands research note investigation of babesia sp. in pygoscelid penguins at the south shetland islands ralph eric thijl vanstreels a,b,c, francisco c. ferreira junior d, daniela de angeli dutra d, sabrina epiphanio e, érika m. braga d, pierre a. pistorius b,c & josé luiz catão-dias a alaboratório de patologia comparada de animais selvagens, departamento de patologia, faculdade de medicina veterinária e zootecnia, universidade de são paulo, são paulo, brazil; bmarine apex predator research unit, institute for coastal and marine research, nelson mandela university, port elizabeth, south africa; cdepartment of science and technology and national research foundation centre of excellence at the fitzpatrick institute for african ornithology, department of zoology, nelson mandela university, port elizabeth, south africa; ddepartamento de parasitologia, instituto de ciências biológicas, universidade federal de minas gerais, belo horizonte, brazil; elaboratório de imunopatologia celular e molecular da malária, departamento de análises clínicas e toxicológicas, faculdade de ciências farmacêuticas, universidade de são paulo, são paulo, brazil abstract babesia spp. are tick-borne parasites, and 16 avian-infecting species have been described to date, including one species (babesia peircei) that infects penguins. considering the results of a recent study reporting babesia sp. in penguins on deception island, south shetland islands, we reexamined the samples obtained in a previous investigation on the occurrence of blood parasites in adult adélie (pygoscelis adeliae), chinstrap (pygoscelis antarcticus) and gentoo penguins (pygoscelis papua) on king george and elephant islands, south shetland islands. notwithstanding a comprehensive re-examination of the blood smears, babesia sp. was not detected. when we employed two nested pcr tests targeting the 18s rrna gene of babesia, a considerable proportion of the samples produced positive results; however, gene sequencing revealed these were due to crossamplification of non-target organisms. we therefore did not detect babesia sp. infection in penguins on king george and elephant islands. additional studies will be valuable to clarify the distribution and epidemiology of tick-borne pathogens in sub-antarctic and antarctic seabirds. keywords antarctica; blood; seabird; spheniscidae; tick-borne pathogen abbreviation pcr: polymerase chain reaction technique babesia spp. are tick-borne protozoan parasites (apicomplexa: piroplasmida) that infect birds and mammals. sixteen avian-infecting species have been described to date (peirce 2000; yabsley et al. 2009; peirce & parsons 2012), and one species, babesia peircei, is known to infect penguins (earlé et al. 1993). in a previous study (vanstreels et al. 2013), we investigated the occurrence of blood parasites in adélie (pygoscelis adeliae), chinstrap (pygoscelis antarcticus) and gentoo penguins (pygoscelis papua) sampled in the south shetlands islands in 2011/ 12. we found no evidence of parasites in blood smears, and did not detect dna from haemoproteus and plasmodium through nested pcr testing targeting the cyt-b gene. considering that previous studies examining blood smears of pygoscelid penguins in the south shetland islands and along the antarctic peninsula had failed to detect any blood parasites (myrcha & kostelecka-myrcha 1980; zinsmeister & van der heyden 1987; merino et al. 1996; moreno et al. 1998; vleck et al. 2000; gonzález-acuña et al. 2013), this led us to suggest that blood parasites were likely absent in penguins breeding in the archipelago. however, montero et al. (2016) found evidence of the occurrence of babesia sp. in chinstrap penguins at deception island, south shetland islands, while examining samples collected during the 2012/13 breeding season. intraerythrocytic inclusions consistent with babesia sp. were seen in the blood smears of 23% of chicks (7/30) and 24% of adults (12/50). when the samples from smear-positive individuals were tested with a newly designed semi-nested pcr targeting a fragment of the 18s rrna gene, however, only 13% of chicks (4/30) and 16% of adults (8/50) were confirmed as positive. phylogenetic analysis of a short fragment of the 18s rrna gene revealed a high similarity to babesia sp. from little penguins (eudyptula minor) from australia. intrigued by these results, we thoroughly re-evaluated the samples from our original study (vanstreels et al. 2013), this time also employing molecular methods specifically targeting babesia sp. materials and methods we re-evaluated blood smears from 64 adult pygoscelid penguins sampled in 2011/2012 in the south shetland islands: keller peninsula (62°4ʹ55ʺs 58°24ʹ32ʺw; seven p. antarcticus, 18 p. papua), demay point (62°12ʹ25ʺs contact ralph eric thijl vanstreels ralph_vanstreels@yahoo.com.br laboratório de patologia comparada de animais selvagens, departamento de patologia, faculdade de medicina veterinária e zootecnia, universidade de são paulo, avenida prof. dr. orlando marques de paiva 87, são paulo 05508-270, brazil polar research 2018, vol. 37, 1500267 https://doi.org/10.1080/17518369.2018.1500267 © 2018 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0003-2359-4828 http://orcid.org/0000-0002-2034-4121 http://orcid.org/0000-0003-2341-2035 http://orcid.org/0000-0001-6094-9750 http://orcid.org/0000-0001-5550-7157 http://orcid.org/0000-0001-6561-7069 http://orcid.org/0000-0003-2999-3395 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2018.1500267&domain=pdf 58°27ʹ7ʺw; 10 p. antarcticus) and thomas point (62° 10ʹ23ʺs 58°28ʹ31ʺw; two p. adeliae, one p. antarcticus, two p. papua) at admiralty bay, king george island, and stinker point, elephant island (61°13ʹ20ʺs 55° 21ʹ35ʺw; 24 p. papua). an experienced observer (r.e.t. vanstreels) evaluated an additional 105 cells (in the original study we had examined 3 × 104 cells) under 1000× magnification. frozen blood samples were available for a subset of these individuals (two p. adeliae, 17 p. antarcticus, 19 p. papua; all from king george island). dna was extracted from the blood samples in the laboratory using a standard phenol/chloroform and proteinase k extraction followed by ethanol precipitation (sambrook et al. 2001) and non-phenolic extraction (carvalho 2010); dna extraction was verified and quantified with nanodrop 2000 spectrophotometry (thermoscientific). quality of extracted dna was further verified through molecular sexing (see brummelhaus et al. 2015). samples were tested with two nested pcr tests targeting the 18s rrna gene of babesia: (a) nested pcr1 employs primers bab5.1 and babb (ca. 1800 bp amplicon) followed by babrlbf and babrlbr to amplify a 460–520 bp fragment, and (b) nested pcr2 employs primers bab5.1 and babb followed by bab5.1v2 and bab3.1 to amplify a 1620–1720 bp fragment. pcr protocols were identical to those described by vanstreels et al. (2015). gel electrophoresis was conducted to visualize amplification products, using 2% agarose gel electrophoresis with sybr safe (s33102, invitrogen) and 6% polyacrylamide gel electrophoresis with silver staining. pcr amplification products of positive samples were purified with polyethylene glycol 8000. bi-directional sanger sequencing with dye-terminator fluorescent labelling (applied biosystems 4 337 455, life technologies) was performed through automated sequencing (abi prism 3100, applied biosystems). traditional precautions to avoid dna contamination (laminar flow hoods, separate work areas for reaction mixture preparation, dna extraction, primary and secondary amplification reactions and gel electrophoresis) were used to prevent carry-over of amplified products. blood from a cape cormorant (phalacrocorax capensis) naturally infected with babesia ugwidiensis and blood from a chicken raised in an arthropod-free environment were used as controls in all reactions; the amplification products of the positive control were sequenced to verify the reaction. results we did not observe any parasites while re-examining the blood smears. nested pcr1 identified 75% of the chinstrap penguins (12/16), 37% of the gentoo penguins (7/19) and none of the adélie penguins (0/2) as positive, with electrophoretic bands of approximately 530 bp (whereas the positive control had approximately 510 bp). nested pcr2 agreed with nested pcr1 for all but one individual: 69% of the chinstrap penguins (11/16), 37% of the gentoo penguins (7/19) and none of the adélie penguins (0/2) were positive, with electrophoretic bands of approximately 1660 bp (whereas the positive control had approximately 1560 bp). these results were consistent when all nested pcr tests were repeated. however, despite two to four attempts to sequence the amplification products from each sample, gene sequencing was largely unsuccessful, as samples failed to produce chromatograms with acceptable quality. for three samples, however, partial sequences (112–401 bp) with high similarity to the 18s rrna gene of fungi (98– 99% sequence identity to saccharomyces cerevisiae) were produced (genbank mg745326–8), indicating crossreactivity of the primers with non-target organisms, presumably fungal contaminants. discussion despite our thorough re-examination of the samples from our previous study (vanstreels et al. 2013), we could not find any morphological or molecular evidence of babesia infections in adélie, chinstrap and gentoo penguins on king george and elephant islands. the fact that the primers used to target the 18s rrna gene of piroplasmids can also amplify the gene sequences of non-target fungal organisms is not unexpected considering that they were originally intended for phylogenetic studies and were designed to target highly conserved regions (medlin et al. 1988; gubbels et al. 1999; criado-fornelio et al. 2003), hence they were not designed to be genus-specific for diagnostic purposes. previous studies have shown that primers targeting the 18s rrna gene of avian piroplasmids may also occasionally cross-amplify host dna (vanstreels et al. 2015; montero et al. 2016). our results underscore that when using primers targeting highly conserved sequences such as the 18s rrna gene, it is imperative to sequence amplification products, and only sequencing-confirmed results should be considered as positive in estimates of piroplasmid prevalence. despite their inherent limitations in terms of specificity, the primers targeting the 18s rrna gene employed in this study have been successfully employed in other studies to detect babesia spp. in birds (yabsley et al. 2006; yabsley et al. 2009), including penguins (vanstreels et al. 2015; yabsley et al. 2017). unfortunately, the 18s rrna gene sequence produced by montero et al. (2016) for babesia sp. from chinstrap penguins at deception island was very short (228 bp excluding primers) and does not cover the annealing sites of the primers employed in this study. it is therefore not possible at present to determine the sequence identity between the primers employed in this study and that of the babesia strain reported by montero et al. (2016). however, considering that the partial 18s rrna gene 2 r.e.t. vanstreels sequence produced by montero et al. (2016) has a high identity to the sequence of babesia sp. from little penguins (226/228 nucleotides; 99.1% ) that was produced using the same methods as in this study (see vanstreels et al. 2015), it seems reasonable to assume that the primers and protocols employed in this study would have been successful in detecting the babesia sp. strain reported by montero et al. (2016) if it had been present in the studied samples. the fact that we did not detect babesia sp. in this study could be related to our relatively small sample size and/or to a lower prevalence of ticks at the studied colonies than on deception island. barbosa et al. (2011) found that the abundance of stones with ticks was much higher in the deception island penguin colony (26%) than at other colonies along the south shetland islands (0 – 10%), including stranger point (9%). it is therefore plausible that the remarkably high prevalence of babesia sp. found by montero et al. (2016) at penguins sampled at deception island might be related to the abundance and distribution of ticks at that colony. alternatively, it is also possible that the high babesia prevalence reported at deception island may have been an overestimation or represent an unusual epidemiological circumstance, i.e., an epizootic. it should be noted that although the babesia-positive penguins studied by montero et al. (2016) were apparently healthy, there is evidence that babesia infections can be pathogenic to seabirds. babesia infection may lead to mild anaemia in little penguins (eudyptula minor; sergent et al. 2004) and is associated with mild anaemia, leukocytosis and impairment of hepatic function in african penguins (spheniscus demersus; parsons et al. 2016). furthermore, there are cases of babesia hyper-infections leading to the death of common murres (uria aalge; yabsley et al. 2009) and a king penguin (aptenodytes patagonicus) during rehabilitation (parsons et al. 2017). it is therefore clear that additional studies are necessary to provide insight into the epidemiology of tick-borne pathogens on antarctic seabirds, especially considering their potential implications to the health and conservation of these species and the predictions that ticks will shift their distribution under climate change (süss et al. 2008; ogden & lindsay 2016). acknowledgements we are thankful to our colleagues who contributed in the original study, and to the support of the universidade federal de minas gerais, instituto de ciências farmacêuticas da universidade de são paulo, programa antártico brasileiro, ministério do meio ambiente, ministério da ciência, tecnologia e inovação, comissão interministerial para os recursos do mar and marinha do brasil. we are grateful to nola parsons, lisa nupen, angélica sarmiento, jorge oyakawa, michael yabsley and hannah munro for their contributions to this study. disclosure statement no potential conflict of interest was reported by the authors. funding this work was supported by são paulo research foundation (fapesp 2009/53956-9, 2010/51801-5), program for technological development in tools for health, national counsel of technological and scientific development, brazilian federal agency for the support and evaluation of graduate education and the south african national research foundation. orcid ralph eric thijl vanstreels http://orcid.org/0000-00032359-4828 francisco c. ferreira junior http://orcid.org/0000-00022034-4121 daniela de angeli dutra http://orcid.org/0000-00032341-2035 sabrina epiphanio http://orcid.org/0000-0001-60949750 érika m. braga http://orcid.org/0000-0001-5550-7157 pierre a. pistorius http://orcid.org/0000-0001-6561-7069 josé luiz catão-dias http://orcid.org/0000-0003-29993395 references barbosa a., benzal j., vidal v., d’amico v., coria n., diaz j., motas m., palacios m.j., cuervo j.j., ortiz j. & chitimia l. 2011. seabird ticks (ixodes uriae) distribution along the antarctic peninsula. polar biology 34, 1621–1624. brummelhaus j., valiati v.h. & petry m.v. 2015. morphometric variation in chinstrap penguins: molecular sexing and discriminant functions in the south shetland islands, antarctica. antarctic science 27, 327–332. carvalho a.l. 2010. estudo de um polimorfismo no gene da cadeia pesada β da miosina (cpβm). (study of a polymorphism in the beta-myosin heavy chain gene.) coimbra, portugal: universidade de coimbra. accessed on the internet at http://fisica.uc.pt/fb/discs/wc.show_ doc.php?id_disc=150&id_turma=&id_typ=19&id_typ doc=2&id_doc=21490&anolect=20092010 11 june 2013. criado-fornelio a., martinez-marcos a., buling-saraña a. & barba-carretero j.c. 2003. presence of mycoplasma haemofelis, mycoplasma haemominutum and piroplasmids in cats from southern europe: a molecular study. veterinary microbiology 93, 307–317. earlé r.a., huchzermeyer f.w., bennett g.f. & brossy j.j. 1993. babesia peircei sp. nov. from the jackass penguin. south african journal of zoology 28, 88–90. gonzález-acuña d., hernández j., moreno l., herrman b., palma r., latorre a., medina-vogel g., kinsella m.j., martín n., araya k., torres i., fernandez n. & olsen b. 2013. health evaluation of wild gentoo penguins (pygoscelis papua) in the antarctic peninsula. polar biology 36, 1749–1760. gubbels j.m., de vos a.p., van der weide m., viseras j., schouls l.m., de vries e. & jongejan f. 1999. simultaneous detection of bovine theileria and babesia polar research 3 http://fisica.uc.pt/fb/discs/wc.show_doc.php?id_disc=150%26id_turma=%26id_typ=19%26id_typdoc=2%26id_doc=21490%26anolect=20092010 http://fisica.uc.pt/fb/discs/wc.show_doc.php?id_disc=150%26id_turma=%26id_typ=19%26id_typdoc=2%26id_doc=21490%26anolect=20092010 http://fisica.uc.pt/fb/discs/wc.show_doc.php?id_disc=150%26id_turma=%26id_typ=19%26id_typdoc=2%26id_doc=21490%26anolect=20092010 species by reverse line blot hybridization. journal of clinical microbiology 37, 1782–1789. medlin l., elwood h.j., stickel s. & sogin m.l. 1988. the characterization of enzymatically amplified eukaryotic 16-like rrna-coding regions. gene 71, 491–499. merino s., barbosa a., moreno j. & potti j. 1996. absence of haematozoa in a wild chinstrap penguin pygoscelis antarctica population. polar biology 18, 227–228. montero e., gonzález l.m., chaparro a., benzal j., bertellotti m., masero j.a., colominas-ciuró r., vidal v. & barbosa a. 2016. first record of babesia sp. in antarctic penguins. ticks and tick-borne diseases 7, 498–501. moreno j., león a., fargallo j.a. & moreno e. 1998. breeding time, health and immune response in the chinstrap penguin pygoscelis antarctica. oecologia 115, 312–319. myrcha a. & kostelecka-myrcha a. 1980. hematological studies on antarctic birds. i. hematological indices in some species of the birds studied during australian summer. polish polar research 1, 169–173. ogden n.h. & lindsay l.r. 2016. effects of climate and climate change on vectors and vector-borne diseases: ticks are different. trends in parasitology 32, 646–656. parsons n.j., gous t.a., cranfield m.r., cheng l.i., schultz a., horne e., last r.p., lampen f., ludynia k., bousfield b., strauss v., peirce m.a. & vanstreels r.e.t. 2017. novel vagrant records and occurrence of vector-borne pathogens in king penguins (aptenodytes patagonicus) in south africa. polar biology 41, 79–86. parsons n.j., schaefer a.m. & vanstreels r.e.t. 2016. health evaluation of african penguins (spheniscus demersus) in southern africa. onderstepoort journal of veterinary research 83, a1447, doi: 10.4102/ojvr. v83i1.1147. peirce m.a. 2000. a taxonomic review of avian piroplasms of the genus babesia starcovici, 1893 (apicomplexa: piroplasmorida: babesiidae). journal of natural history 34, 317–332. peirce m.a. & parsons n.j. 2012. babesia ugwidiensis, a new species of avian piroplasm from phalacrocoracidae in south africa. parasite (paris, france) 19, 375–379. sambrook k.j., russel d.w. & sambrook j. 2001. molecular cloning: a laboratory manual. new york: cold spring harbor laboratory press. sergent n., rogers t. & cunningham m. 2004. influence of biological and ecological factors on hematological values in wild little penguins, eudyptula minor. comparative biochemistry and physiology a, molecular and integrative physiology 138, 333–339. süss j., klaus c., gerstengarge f.w. & werner p.c. 2008. what makes ticks tick? climate change, ticks, and tick-borne diseases. journal of travel medicine 15, 39–45. vanstreels r.e.t., miranda f.r., ruoppolo v., reis a.o.a., costa e.s., pessôa a.r.l., torres j.p.m., cunha l.s.t., piuco r.c., valiati v.h., gonzález-acuña d., labruna m., petry m.v., epiphanio s. & catão-dias j.l. 2013. investigation of blood parasites of pygoscelid penguins at the king george and elephant islands, south shetlands archipelago, antarctica. polar biology 27, 135–139. vanstreels r.e.t., woehler e.j., ruoppolo v., vertigan p., carlile n., priddel d., finger a., dann p., herrin k.v., thompson p., junior f.c., braga e.m., hurtado r., epiphanio s. & catão-dias j.l. 2015. epidemiology and molecular phylogeny of babesia sp. in little penguins eudyptula minor in australia. international journal of parasitology—parasites and wildlife 4, 198–205. vleck c.m., vertalino n., vleck d. & bucher t.l. 2000. stress, corticosterone, and heterophil to lymphocyte ratios in free-living adelie penguins. the condor 102, 392–400. yabsley m.j., greiner e., tseng f.s., garner m.m., nordhausen r.w., ziccardi m.h., borjesson d.l. & zabolotzky s. 2009. description of novel babesia species and associated lesions from common murres (uria aalge) from california. journal of parasitology 95, 1183–1188. yabsley m.j., vanstreels r.e.t., shock b.c., purdee m., horne e.c., peirce m.a. & parsons n.j. 2017. molecular characterization of babesia peircei and babesia ugwidiensis provides insight into the evolution and host specificity of avian piroplasms. international journal of parasitology—parasites and wildlife 6, 257–264. yabsley m.j., work t.m. & rameyer r.a. 2006. molecular phylogeny of babesia poelea from brown boobies (sula leucogaster) from johnston atoll, central pacific. journal of parasitology 92, 423–425. zinsmeister v.a.p. & van der heyden m.j.n. 1987. differential leucocyte cell counts from the pygoscelid penguins of antarctica. journal of wildlife diseases 23, 521–523. 4 r.e.t. vanstreels https://doi.org/10.4102/ojvr.v83i1.1147 https://doi.org/10.4102/ojvr.v83i1.1147 abstract materials and methods results discussion acknowledgements disclosure statement funding references the pelagic distribution of little auk azze azze in relation to a frontal system off central norway, marchiapril 1988 arne follestad follestad, a. 1990: the pelagic distribution of little auk alle afle in relation to a frontal system off central norway, march/april 1988. polar research 8, 23-28. large concentrations of little auks were recorded off central norway in march and april 1988. their pelagic distributional patterns may be related to the frontal system between atlantic water and the coastal stream off central norway. peak densities of more than 1,ooo little auks per km2 were recorded in two areas on the continental shelf, close to the frontal system. these densities were up to 500 times as high as those found in adjacent areas. a change in distribution with season was observed, suggesting a seasonal association with the front. arne follestad, norwegian institute for nature research, tungasletta 2 , n-7004 trondheim, norway; february 1990. n -r$ "polar\n~~'' the effects of fronts upon seabird distribution have been described by several authors (brown et al. 1975; haney & mcgillivary 1985a; kinder et al. 1983). seabirds associated with fronts or upwelling areas are often plankton feeders, such as phalaropes and storm-petrels (briggs et al. 1984; haney & mcgillivary 1985b). brown (1976, 1988) found that little auks appeared to use frontal areas off the coast of canada. the little auk is the only atlantic alcid which feeds pri marily on zooplankton, although small fish may be of importance in the winter diet (blake 1983; bradstreet & brown 1985). observations of seabirds have been made the last few years off the coast of central norway, but the coverage is poor compared to the north sea and the barents sea (tasker et al. 1987; bakken & mehlum 1988; strann & vader 1988). improved coverage of the seas off norway is essential to complete an accurate description of the distribution of little auks in the north sea (tasker et al. 1987). the aim of this paper is t o show that some of the distributional patterns of little auk in coastal waters off central norway in late winter and spring may be related to the frontal system in this area. oceanographic background the coast of central norway is bordered by a continental shelf (< 200 m) which extends about 80-90 km off the coast between 62"n and 63"n. at its outer edge, the 'shelf-break', the continental slope drops abruptly to depths greater than 1,000m. there are two important water masses along the norwegian coast, the warm and saline atlantic water, and the cold and less saline norwegian coastal stream. the coastal stream originates from the baltic stream and runs north wards along the coast of norway, where it mixes with fresh water from rivers and oceanic water of higher salinity and density, lying outside and beneath the coastal stream (sztre et al. 1979). the oceanic water moves slowly when com pared to the coastal stream, which attains speeds up to 100 cm/sec (2 knots), and averages between 15 and 40cm/sec. highest speeds are normally found in the surface layers, where north winds may reverse the stream, followed by a rapid movement northwards. these high velocities usually occur some distance from the coast, often at the edge of the continental shelf (sretre et al. 1979). the two water masses meet in a frontal system, which runs along a major part of the norwegian coast. this front may be defined broadly by large horizontal gradients of water properties such as temperature, salinity and den sity (see joyce 1983; le fevre 1986). fronts where surface temperature gradients may be as high as %4"c/5 km are not uncommon along the coast of western and central norway during the winter (r. sretre pers. comm.). biological characteristics of 24 4rne follestad 6 9 o 6 8 o 6 7 o 6 6 o 65‘ 64( 63o 20 6 o 100 1 20 1 4 o 1 6 o 62c fig. 1 . survey route of the research vessel f/f ‘eldjarn’ 22 feburary-24 march 1988. ctd stations are marked with a ‘z’ frontal systems through their complex circulation patterns, such as enhanced production and accumulation of plankton, of which higher trophic animals may take advantage, are reviewed by le fevre (1986). methods and data the surveyed area is shown in fig. 1. little auks were observed from the bridge of f/f ‘eldjarn’ within a 300 m transect while moving at a speed of 11-12 knots. standard procedures were used (tasker et al. 1984) with one alteration in the procedure. because little auks are difficult to observe at sea, binoculars were regularly used to scan the surface to detect little auks within the transect. this change in procedure may make it difficult to compare these data with those from some other surveys in the northeastern atlantic, but this shortcoming is offset by the increase in accuracy attained. the vertical distribution of salinity and of tem perature were observed using a ctd (con ductivity-temperature with depth) with a rosette sampler. distribution of little auk 25 results little auks were present mainly south of 64"n in a non-random distribution (fig. 2a and b). most little auks were recorded on the continental shelf, but were also found in low numbers more or less evenly distributed all the way out to the greenwich meridian. maximum densities of little auks (10-25 birds/ km2) in atlantic waters were recorded on 22 march, between ctd st. no. 252 and 253 (see fig. 1). some of these concentrations of birds may have been related to an eddy in the water, but no data on plankton, fish or hydrography were collected on this transect. acoustic records indicate, however, a regular occurrence of zooplankton. in the coastal stream, large concentrations of up to 300-400 little auks/km2 were found near land on 4-6 march, but no observations were made farther offshore during this period (fig. 2a). from the middle of march they were found in high numbers on the continental shelf south of 64"n, with few close to the coast (fig. 2b). when areas north to 69"n were surveyed in the middle of march, only a few little auks were observed with no particular concentrations evident. at the end of march and in early april, however, very high densities of little auks, between 900 and 1,500 birds/km2, were recorded in two areas on table 1. mean densities of little auks in two areas with very high numbers of birds. density is calculated on the basis of a transect width of 300m and a speed of 11 knots. number of date duration little auks mean density (1988) (min.) observed (birds/kmz) 23 march 45 4,900 1,070 27 march 48 5,800 1,190 the continental shelf between 62'30" and 63'30" (table 1). the mean density of little auks in atlantic water on 23 march was 1.7 birds/ km2. on 23 march, returning from the greenwich meridian to the coastal areas near svincby (62"20'n, 5'16'e), salinity and temperature were measured at intervals (ctd st. no. 253-269 in fig. 1). close to the edge of the continental shelf there was a front between the atlantic and coastal water with a rapid change in surface temperature (7.5 to 5oc) and salinity (35 to 33%0, fig. 3). this front could also be seen on the water surface as turbulence. the number of little auks observed in each 10-minute period along this transect increased very rapidly at the frontal area, from almost zero to 900-1,200 birds (fig. 3 ) . on 27 march, high densities were found about 100 km farther north, east of buagrunnen fig. 2. (a) distribution of little auks before 15 march 1988. size of plots is 20 x 20 km. filled symbols indicate a density of at least 200 birds/km2. small symbols represent transect lines that were less than 6 km long. (b) distribution of little auks after 15 march 1988. 26 arne follestad l 256 260 265 269 1 i i , , i fig. 3. (a) the number of little auks observed per 10-minute interval. black squares beneath the line indicate the 10-minute intervals covered. (b) temperature (t in "c) and salinity (s in % o ) . ctd st. nos. are given at the top (cf. fig. 1). discussion the normal winter range of little auks in the eastern atlantic extends south to the north sea and skagerrak area, as shown by surveys of seabirds at sea (see review in brown 1985; tasker et al. 1987) and by their presence among seabirds (63"05'n, 6"30'e); large numbers of birds were also seen on 1 april at buagrunnen. buagrunnen is an important spawning area for herring clupea harengus, and sampling indicated a high con centration of herring larvae present (r. saetre pers. comm.). distribution of little auk 27 found dead after the oil spill in skagerrak 1980/ 81 (anker-nilssen & rastad 1981). little auks are commonly found in the north sea, but accord ing to recent research only in small numbers (tasker et al. 1987). little auks are regular visitors t o the norwegian coast in winter (norderhaug et al. 1977) where they are sometimes observed in immense numbers, even inshore. for example on 26 january 1986, 5,000 to 15,000 little auks were recorded (follestad e t al. 1986) between the islands of hitra and froya (63”40’n, 9’00’e). large numbers of little auks were found close to the coast in early march 1988, with high den sities only occurring at or close to the front at the continental shelf edge after 15 march. two different patterns of little auk distri bution seemed to occur during march and april 1988. in the warm and saline atlantic water, little auks were more or less evenly distributed in low numbers. in the cold and less saline coastal stream, or close to the frontal system between these two water masses, their distribution was patchy, and they were sometimes present in very high numbers. more data should be collected on the distri butional pattern of little auks along the coastline to see if they move from inshore areas to the front at certain times. the reason for the high concentrations of little auks associated with the frontal system off the coast of central norway is not clear, but fronts in the north sea often coincide with regions of increased primary pro duction (see le f&vre 1986). in water off central norway phytoplankton production in spring will at first increase at the front and in the mixed coastal water masses (r. sztre pers. comm.). during this survey, no data on plankton or fish were collected, but acoustic observations indi cated that little auks were concentrated where food was abundant. little auks may take advan tage of more available food at frontal systems due to enhanced production and accumulation of zooplankton (see review by le fkvre 1986). there is evidence that little auks feed where prey is most concentrated (bradstreet & brown 1985), and a better understanding of the winter and spring distribution of little auks off central nor way will require more detailed studies of their diet seasonally and the distribution of their prey. densities of 1,000-1,500 little auks per km’, as was observed in two areas, are exceptionally high compared to those found in the western part of the north sea where mean densities rarely occur above 2 birds/km2 (tasker et al. 1987). future studies on the little auk should give priority to oceanographic and biological factors that may influence the distribution of the birds at sea, as well as the impact such a huge number of birds may have on the population dynamics of zooplankton and fish. acknowledgemenrs. i thank the norwegian institute of marine research for permission to observe seabirds from their research vessel f/f ‘eldjarn’, the crew for their help, and r. satre for providing unpublished information on temperature and salinity. i also thank david n. nettleship, nancy harrison, and rob barrett for comments on the manuscript. the studies were financed by the norwcgian royal ministry of petroleum and energy. references anker-nilssen, t. & r@stad, 0. w . 1981: unders~kelser av oljeskadede sl0fugler i forbindelse med oljekatastrofen i ska gerrak desember 1980/januar 1981. vi!trapport 16. 41 pp. bakken, v. & mehlum, f . 1988. a k u p final report. seabird investigations in the barents sea south, north of n 74”/ b j m n ~ y a . norw. polar res. inst. rep. ser. 4 4 . 179 pp, blake, b. f. 1983: a comparative study of the dict of auks killed during an oil incident in the skagerrak in january 1981. j. zool. lond. 201. 1-12. bradstreet, m. s. w. &brown, r. g. b. 1985: feeding ecology of the atlantic alcidae. pp. 264-318 in nettleship, d . n. & birkhead, t. r. (eds): the atlunric alcidae. academic press, orlando. briggs. k. j . . dettmen, k. f., lewis, d. b. & tyler, b. 1984: phalarope feeding in relation to autumn upwelling off california. pp. 51-62 in nettleship, d. n., sanger, g. a. & springer, p. f. (eds.): marine birds: rheirfeeding ecology and commercial fisheries relationships. canadian wildlife service speciul pu blicafion. 0 t t awa . brown, r. g. b. 1976: the foragingrange of breeding dovekies alle alle. cunadian field-naturalist 90, 166168. brown, r. g . b. 1985: the atlantic alcidae at sea. pp. 3 8 4 427innettleship. d . n. & birkhead, t. r . (eds): theatlantic alcidae. academic press, orlando. brown, r. g. b. 1988: oceanographic factors as determinants of the winter range of the dovekie (ane alle) off atlantic canada. colotiial wuterbirdr 1 1 , 176.180. brown, r. g. b., nettleship, d. n., germain, p.,tull. c. e. & davis, t. 1975: atlas of eastern canadian seabirds. canadian wildlife service, ottawa. 220 pp, follestad, a., larsen, b. h. & nyglrd, t. 1986: seabird and waterfowl surveys on the coast of south and north trdndelag and southern parts of nordland 1983-86. vilrrapport 41. 112 pp. (in norwegian with english summary). haney, i. c. & mcgillivary, p. a . 1985a: midshelf fronts in the south atlantic bight and their influence on seabird distribution and seasonal abundance. biological oceano graphy 3 . 401-430. haney, 3 . c. & mcgillivary, p. a . 1985b: aggregations of cory’s shearwaters (calonecris diomedea) at gulf stream fronts. wilson bull. 97, 191-200. 28 arne follestad joyce, t . m. 1983: varieties of ocean fronts. in stern, m . e. & mellor, f. k. (eds.): baroclinic lnstabilify and ocean fronts. technical report 83-41, woods hole oceanographic institution. kinder, t. h . , hunt, g. l.. schneider, d. & schumacher, j. d. 1983: correlations between seabirds and oceanic fronts around the pribilof islands. alaska. est. coastal and shelf science 16. 309-319. le fevre, j . 1986: aspects of the biology of frontal systems. advances in marine biology 23, 163299. norderhaug. m., brun, e. & mollen, g. u . 1917: barents havets sj~fuglressurser (seabird resources of the barents sea). norsk polarinstiturt meddelelser 104, 1-119. strann, k.-b. & vader, w . 1988: registrering av sjofugl i barentshavet syd. akup 1985-1988. tromura, natur uitemkap 63. 41 pp. 74 maps. satre, r., sundby, s. & loeng, h. 1979: endel fysisk oseanografiske trekk langs den nordlige del av norskekysten. pp. 45-66 in om oirkninger ao oijeforurensninger i nordiige faruann. foh-report 1 1979. tasker. m. l., jones, p. h., dixon. t. j . & blake, b . f. 1984: counting seabirds at sea from ships: a revicw of methods cmployed and a suggestion for a standardized approach. auk 101, 561-511. tasker, m. l., webb, a,, hall, a. j . , pienkowski. m. w. & langslow, d. r. 1987: seabirdr in the north sea. nature conservancy council, aberdeen. 336 pp. no job name b o o k r e v i e w por_115 313..315 review of explorer: the life of richard e. byrd, by lisle a. rose (2008). columbia, mo: university of missouri press. 544 pp. isbn 978-0-8262-1782-0. with his hollywood good looks, commander’s stripes, boyish humility, overweening faith in the righteousness of american technological progress, and bags of cash from some of america’s most reactionary republican businessmen, richard evelyn byrd in the late 1920s stepped neatly into the role of globally recognized polar superstar, a magnificently tricky job made vacant by roald amundsen’s chivalric disappearance north of tromsø during the italia catastrophe of 1928. in a geographic world soon to be taken over by science bureaucrats in national directorates and emerging research institutions, byrd, a naturally sensitive and deep thinker, self-reinvented as a muscular man of action, became a final bastion of the fading cult of polar personality. this biography of the “admiral of the antarctic” attempts to chart byrd’s life, but never quite decides whether this goal should be reached through a modernist celebration of the great man, through a critical postmodern analysis of byrd’s real, as well as disputed, exploits or by simply laying waste to anyone who ever dared take issue with the execution of those adventures. as such, the volume fails to achieve a consistent tone: not least in its stated hope of resurrecting something of the maudlin american appreciation for lonesome action heroes. byrd’s credo was more than robert peary’s monomaniacal “i must have fame”, but not much more. the author sets out on his trek by proclaiming “there are no heroes now” (p. 1), a threadbare thesis when one considers, among dozens of other examples, the 343 new york city firemen who lost their lives trying to save citizens from 90 different nations on the morning of 11 september 2001. what the author really means is that in a post-modern age, people are rightly skeptical of the heroic. this sense of a world stripped of the heroic is one the author never connects with its obvious conclusion: one of the primary reasons for this cynicism is the sad lineage of american fakery at the north pole. when it came to the “big nail”, and recalling that elisha kent kane and isaac israel hayes claimed far more progress northwards towards a chimerical “open polar sea” than they ever managed, or recalling the poisoning of charles francis hall, the us navy’s jeannette failure, the us army’s greely catastrophe, the magnificent calumnies of frederick cook, robert peary, and, yes, richard byrd—not to mention the tragicomic efforts of walter wellman, evelyn baldwin and anthony fiala—it is clear that the american action hero failed, failed repeatedly, and failed mightily. it is no wonder then, once both poles had been captured, that americans generally concluded that further polar research was either a publicity scam/confidence game or a marginal science pursuit better left to government bureaucrats, university geologists and norwegians. richard evelyn byrd was born into a once-prominent virginia family that had come down a step or two by the late 19th century. byrd and his two brothers, tom and harry, were determined to rebuild the family name, correspondence p.j. capelotti, division of social and behavioral sciences, pennsylvania state university, abington college, abington, pa 19001, usa. e-mail: pjc12@psu.edu polar research 28 2009 313–315 © 2008 the author 313 mailto:pjc12@psu.edu fortune and connections, and they succeeded. harry in particular became invaluable in aiding his brother, richard’s, career in the us navy, first as a conservative newspaper publisher, and later as governor and us senator from virginia. just three years after his graduation from the us naval academy in 1912, byrd was already serving a plum assignment on board the presidential yacht. fifteen years later, when byrd was barely 40 years old and mere moments after the successful conclusion of his flight to the south pole, his brother harry rammed legislation through congress in 48 hours that made richard a rear admiral. these career leaps, as well as richard byrd’s skill at massaging a washington, d.c. bureaucracy to advance his polar ambitions, are detailed well here. byrd’s ability to promote his expeditions by attaching his name to products and sponsors near and far was also remarkable, although even his puritanical patrons at the national geographic society thought he had over-commercialized himself and his first antarctic expedition (p. 277). byrd’s true skill was as an expedition organizer, and such talent is not to be despised, although the author makes it abundantly clear that it was greatly despised by many who believed that byrd was all fund-raiser and no explorer. but, byrd faced unique pressures. by the time he had arrived on the scene, most of the world had already been discovered. all that was left was to rediscover the world in different ways, and for byrd that meant using aircraft. one fascinating tidbit herein is that prior to joining the 1925 macmillan expedition to etah, byrd sought to reach the north pole with a military tc-type dirigible: a 230 000 cubic foot non-rigid airship with a cruising radius approaching 1000 miles (p. 64). byrd wanted to build a hangar in northern greenland, and to somehow put down a supply cache near the pole, where the airship could resupply. it was an audacious and bold plan, and followed an almost identical airship expedition—in a kind of motorized free balloon—that had been attempted by walter wellman in 1907 and 1909. although the two are not connected here, byrd would have been a freshman at the naval academy during wellman’s final polar attempt, and almost certainly would have read of it. such expeditionary detail is largely missing in this volume, until it arrives at the chapters devoted to byrd’s second antarctic expedition. these sections are handled well, and it seems at times that the book is really a history of this expedition that was found to be too short for a full-length manuscript, and so an extended introduction and epilogue were added, and thus it became a fully fledged attempt at a life story. the writer possesses an unfortunate habit of swapping between byrd’s names, as if the author was on personal terms with him. byrd is variously “byrd”, “richard”, “dick”, “dickie”, “reb”, “richard byrd”, “dick byrd”, etc. it would have been far less jarring to pick one of these and use it throughout. at one point the author states his belief that byrd’s near insanity at advance base during the second expedition in 1934 was caused by his stove (p. 354). six pages later he writes that byrd should have known that his stove “was perfectly safe”. we read of “whale sperm oil” (p. 406), when the author presumably means “sperm whale oil” or, more correctly, simply “whale oil”. there are enough flaws in the aviation history and polar geography to make one take note. the author traces the rise of the air meet to “as early as 1912 and 1913” (p. 42), when the meet at rheims took place in 1909, and when balloon meets pre-dated this by several years. roald amundsen’s knowledge of aeronautics is described as “too sketchy to match his dreams” (p. 71), a rather remarkable claim against someone who led the first lighter-than-air expedition over the north pole, and came within an ace of being the first to the pole in a heavierthan-air craft. the author’s familiarity with antarctic terrain is not matched in the north. his description of byrd going “to the island of spitsbergen in the svalbard archipelago north of iceland” (p. 60) leaves much to be desired, as does his description and placement of amsterdamøya as “a bit of bare rock at the very tip of spitsbergen” (p. 120), or his naming of ny-ålesund as “ny aslund” (p. 112). amundsen’s 1925 return flight on the one salvaged dornier “wal” flying boat, piloted by hjalmar riiserlarsen, took off from a 300-m ice field, not the 500 m of water described here. the chronicle of byrd’s much-contested north pole flight of 1926—the very foundation of byrd’s heroic reputation—takes on an unpleasant and ultimately selfdefeating aspect of a score-settling. where other, more adept biographers, such as tor bomann-larsen in roald amundsen, used an explorer’s own actions to delve into their subject’s innermost character, rose uses byrd’s lifetime of questionable actions to launch repeated denunciations of byrd’s critics. the author devotes no less than 20 pages to destroying the critics of byrd’s claim that he was the first human to fly over the north pole. the most prominent critic taken to task on this point is the norwegian master polar aviator, bernt balchen. in the midst of tearing apart balchen, apropos of nothing, he drags norwegian explorer finn ronne into the narrative to take a beating for a paragraph. the author does not even pass on a chance to take a shot at balchen’s widow (p. 478), which is a bit short of the heroic. he describes both balchen and ronne, along with the writer richard montague, as “powerful” enemies, out to destroy byrd (p. 128). but, given byrd’s rank, clout and connections, this description is a little hard to book review polar research 28 2009 313–315 © 2008 the author314 swallow, and the author provides more than enough evidence that byrd was quite capable of doing himself in, as when he made the catastrophic decision to live alone in a small hut buried in the snows of antarctica in 1934. without realizing the implications of this notion, the author instead makes a convincing case that the everparanoid byrd was consumed to near-insanity by the dread that each of his major achievements—from the north pole flight getting off the frozen ground at ny-ålesund, to the 1927 trans-atlantic flight, to the 1929 south pole flight scraping up the liv glacier to the south polar plateau—were in fact the achievements of bernt balchen. sniffing carbon monoxide for four months in a frozen hut in middle age did nothing to improve byrd’s almost congenital insecurities. this theme is woven, but largely unacknowledged, through the book, as if by admitting it the author will condemn the whole life story, rather than producing a fresh analysis. even as the author takes evident delight in dismantling byrd’s critics, he is contradictory, and almost fleeting, in excusing byrd’s unforgiveable carelessness in marking his polar achievements. after he writes that on the north pole of all flights, byrd “could take no chances” (p. 132), he dismisses the discovery of erasures on byrd’s flight diary as evidence of “hasty calculations [that] byrd clearly thought were questions of only momentary value” (p. 133). this is simply not good enough. byrd’s log deletions on 9 may 1926 are the aviation equivalent of peary stuffing a separate page into his diary for 6 april 1909, claiming “the pole at last!!!”. if there was one flight where byrd had to be seen as operating completely above board it was this one. yet, on this of all days, with the white eagle of norway breathing down his neck and ready to fly the norge to and over the pole, richard byrd gives enough evidence of fudging his data that he all but guaranteed that he would be eternally second-guessed. this, of course, is the reason that amundsen surrounded the south pole with all those black flags in 1911, and why he left the polheim tent with a letter inside addressed to robert falcon scott. when it came to the poles, the issue of priority could not be left to chance or doubt. at one point, the author, in a last bid to salvage byrd’s north pole claim, writes that no one has “ever subjected amundsen’s [norge] flight to the brutal skepticism accorded byrd; perhaps simple fairness dictates that they should” (p. 142). this astoundingly absurd notion suggests that the author has doubts that the norge flew over the north pole to alaska. he is the only one. the simple truth is that amundsen had learned the lessons of the peary–cook disaster well; richard byrd did not. the question, of course, is why? it is a given that few of us will ever experience the pressure to perform on a world stage such as that experienced by richard byrd. just as with amundsen, any admission that byrd was human was never on the cards, until it was too late. unlike amundsen, byrd had no great acquired set of polar skills to fall back upon in a crisis. what he did have in him was the one great reflective manuscript alone (1938), in which he changed the arc of the explorer from physics to metaphysics. but even this triumph made his smoothness seem either superhuman or an act. it is an old axiom that a great challenge does not build character, but rather reveals it. byrd’s experiences at advance base revealed that the admiral of the antarctic had engaged in a lifelong and almost superhuman act of self-deception. unfortunately, by the end of this considerable effort, one feels no closer to a revelation of this strange and multifarious character than at the start. book review polar research 28 2009 313–315 © 2008 the author 315 phytoplankton dynamics in the barents sea estimated from chlorophyll budget models maria vernet vernet, m. 1991: phytoplankton dynamics i n the barents sea estimated from chlorophyll hudgct models. pp. 129-145 i n sakshaug. e . , hopkins, c. c. e. & britsland. n. a . (cds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, 12-16 may 1990. polar research lo(1). pigment budgets use chlorophyll a and phaeopigment standing stock in combination with their photo oxidation and sedimentation rates in the euphotic zone to estimate phytoplankton growth and grazmg by microand macrozooplankton. using this approach. average phytoplankton growth in the euphotic zone of the barents sea was estimated at 0.17 and 0.14 d ' during spring of 1987 and 0.018 and 0.036 d ' during lateand postbloom conditions in bummer of 1988. spring growth was 65% lower than the estimates from radiocarbon incorporation. supporting a 3 3 % pigment loss during grazing. macrozooplankton grazing and cell sinking were the main loss terms for phytoplankton during spring while microzooplankton grazing was dominant in summer. in contrast to tropical and temperate waters, arctic waters are characterized by a high phaeopigment : chlorophyll a ratio in the seston. photooxidation ratcs of phaeopigments at in situ tem peratures (0 2 1°c) are lower than in temperate waters and vary by a factor of 2 for individual forms (0.009 to 0.018 m-* mol-'). the phaeopigment fraction in both the suspended and sedimenting material was composed of seven main compounds that were isolated using high-performance liquid chromatography and characterized by spectral analysis. the most abundant phaeopigment in the sediment traps, a phaeo phorbide-like molecule of intermediate polarity ( phaeophorbide a , ) , peaked i n abundance in the water column below the 1 % isolume for par (6&80m) and showed the highest rate of photooxidation. this phaeopigment was least abundant in the scston when phytoplankton was dominated by prymnesiophytcs but increased its abundance i n plankton dominated by diatoms. this distribution suggests that larger grazers feeding on diatoms are the main producers of this phaeopigment. maria vernet, marine research division. scripps institution of oceanography. university of california sun diego. la jolla, california 92093-0218. usa. introduction estimates of phytoplankton growth and fate of the newly formed carbon are essential to our understanding of the physical and biological pro cesses that govern the distributions and trans formations of organic matter in an aquatic ecosystem. due to its specificity to plants, chloro phyll a has been successfully used as a tracer of phytoplankton carbon for the last 40 years (richards & thompson 1952) and is one of the best estimators of phytoplankton abundance in marine waters. chlorophyll a degradation prod ucts, in particular the fluorescent compounds, are tracers of phytoplankton carbon in processes such as grazing (currie 1962), sedimentation (lor enzen et al. 1981; bathmann & liebezeit 1986), and diagenesis in sediments (daley & brown 1973; hurley & amstrong 1990). because of their specificity and abundance, photosynthetic pigments have become important tools in phytoplankton identification (jeffrey 1974; hooks et al. 1988). several forms of chloro phyll a (brown 1985; chisholm et al. 1988) and chlorophyll c (jeffrey & wright 1987; nelson & wakeham 1989) in marine phytoplankton are used as tracers of certain phyla. fucoxanthin (stauber & jeffrey 1988), fucoxanthin derivatives (wright & jeffrey 1987; bjmnland et al. 1988), and xanthophylls (gieskes & kraay 1983, 1986; guillard et al. 1985) are b y themselves or in combination with the chlorophylls also used as markers. although not altogether quantitative, this approach is complementary to other tech niques such as microscopy and can give a first approximation to the complexity and composition of the phytoplankton assemblage. chlorophyll degradation products are con sidered quantitative estimators of grazing (shu man & lorenzen 1975) and have been used in laboratory (landry et al. 1984) and field studies (welschmeyer et al. 1984; downs & lorenzen 1985) of herbivory activity. based on premises of stoichiometric degradation of chlorophyll by 130 m. vernet herbivory. welschmeyer & lorenzen (1985) developed a pigment budget model t o estimate phytoplankton growth and losses. this model uses chlorophyll a and phaeopigment standing stock in combination with their photooxidation and sedimentation rates in the euphotic zone t o esti mate phytoplankton growth and grazing by micro and macrozooplankton. t h e model assumes that chlorophyll a is only associated with phyto plankton while phaeopigments a r e product of the stoichiometric degradation of chlorophyll a d u e to grazing (or at least with a known loss fraction). the usefulness of fluorescent degradation prod ucts as quantitative estimation of grazing has been challenged by a number of laboratory studies. klein e t al. (1986), conover e t al. (1986) and lopez et al. (1988) found high and variable (0 99%) pigment losses in grazing experiments. in contrast, field applications have found low (10 33%) losses (dagg & walser 1987; downs 1989). laws et al. (1988), assuming a 33% pigment loss, found high correlation between growth rates esti mated from t h e pigment budget model and radiocarbon incorporation. it is clear that more experimentation is needed before we can under i 80' n 70" 76' 74" 72" 70 " stand the factors associated with this discrepancy. in this study. phytoplankton growth and zooplankton grazing in t h e euphotic zone were estimated by a chlorophyll budget model. dis tribution, sedimentation, and photooxidation rates of phytoplankton pigments, in particular chlorophyll a and its degradation products, are used as indicators of synthesis and transformation of organic carbon in t h e barents sea. when avail able, the output of t h e pigment budget model is compared t o other estimates in order to assess the usefulness of this approach for arctic waters. methods samples for water column and sedimenting par ticles were collected during two cruises to the western barents sea. t h e pro mare cruise 11 o n r/v (3.0. sars from 15 may to 12 j u n e 1987 visited 2 stations with 2 sediment t r a p deployments at each station. pro mare cruise 15. o n norwegian coast g u a r d k / v andenes. from 1 t o 21 july 1988, visited 2 stations with o n e t r a p deployment at each station. dates. positions, depth, and 2 norway fig. i . water masses of the southwestern barents sea: open arrows = atlantic water; striped arrow = coastal water; dashed arrows = polar waters. dotted line = position of polar front; shaded lines = average position of ice edge during summer months as ice recedes northwards. triangles indicate stations visited during spring 1987: open triangle = stns. 947-987; solid triangle = stns. 941-994. circles indicate stations visited during summer 1988: open circle = stn. 864; solid circle = stn. 885. redrawn from rey & loeng (1985). phytoplankton dynamics in the barents sea 131 table 1. location, sediment trap sampling depth, and water column depth of 4 stations visited in the barents sea during this study. the spring bloom was underway in may-june 1987 while summer conditions prevailed in july of 1988. date station latitude longitude trap water column depth depth (m) ( m ) 27 may-6 june 1987 937-947 75"00'n 28"37'e 50 320 2-7 june 1987 947-987 75"gq'n 28"37'e 50 320 21-28 may 1987 894.941 74"29'n 31"31'e 50 230 28 may-8 june 1987 941-994 74"29'n 31"31'e 50 230 13-16 july 1988 864 73"oo'n 31"15'e 100 278 4-7 july 1988 885 75"oo'n 28"00'e 90 330 length of deployments are presented in table 1 and fig. 1. hydrographic profiles of temperature, con ductivity and depth were obtained with a neil brown mk 111 ctd-profiler mounted with a gen eral oceanic rosette sampler equipped with ten 10-1 niskin bottles. the sampling depths were 0, 5 , 10, 20, 30, 50, 75, 100, 150, 200 and 250111. light was measured with a photosynthetically active radiation (par) 4 n collector placed high on the ship superstructure (biospherical instru ments model qsl-40). the extinction of light in the water column was estimated with a 4 n par downwelling irradiance sensor (mer model 1012f optical profiling unit, biospherical instru ments inc.). sedimentation was measured for a period of 3 to 11 days (see table 1) using double cylindrical pvc traps with a height of 1.6 m and a diameter of 0.16 m (h/d ratio of 10). in may-june 1987, traps were deployed at 50 and ioom, while in july 1988 traps were deployed at 60, 100 and 230m at stn. 864 and at 40, 90, 150, 200 and 250 m. no poisons were used during the deploy ments. the rate of carbon decomposition in the sedimenting matter was, on average, not higher than 2% d-l (wassmann et al. 1991). the con tents of each trap were transferred along with about 2 liters. of seawater to a bottle and thoroughly mixed before subsampling. triplicate samples were taken and .filtered for pigments. pigment sedimentation rates were calculated on basis of the concentration in the trap, length of the deployment, and trap surface area. samples were concentrated on whatman gf/ f filters under 50 mbar of differential pressure. samples for high pressure liquid chromatography (hplc) were frozen in liquid n 2 and stored at -70°c until analysis. pigments were extracted overnight at 4°c in the dark with 90% acetone. extracts were cleared by filtration through what man gf/c filters and injected onto the column without further treatment. pigments were estimated using the fluorometric technique of holm-hansen et al. (1965) on a turner designs fluorometer calibrated with chlorophyll a (sigma chemical co.) in 90% acetone. this analysis was performed during both cruises. in addition, samples for the summer cruise of 1988 were analyzed for chlorophyll a and degradation products ( phaeopigments) by high performance liquid chromatography (hplc) on a reverse-phase c-18 brownlee spherisorb ods 5 column, 25 cm x 4.6 mm, 5 pm particles. pig ments were eluted in a low-pressure gradient sys tem consisting of a linear gradient from 100% a to 100% b in 10 min and maintaining b for another 15min. solvent a consisted of 70:20: 10 methanol : water: water + ion pairing agent (v/ v), the latter solvent in a concentration of 1.5 g of tetrabutylammonium acetate and 0.96 g of ammonium acetate in 100 ml of water (mantoura & llewellyn 1983). solvent b consisted of 60:40 methanol :ethyl acetate (v/v). eluting pigments were quantified by fluorescence in a hitachi f 3000 fluorescence spectrophotometer fitted with a flow-through cell, with excitation beam at 410 nm and emission at 680 nm. pigments were identified by their fluorescence excitation spectra (table 2 ) . the hplc column was calibrated with pure pigments prepared as in vernet & lorenzen (1987) from a culture of thalassiosira nor denskioeldii, with extinction coefficients as in lorenzen & downs (1986) for chlorophyll degra dation products, jeffrey & humphrey (1975) for chlorophylls a and c ~ + ~ . because of a lack of a specific absorption coefficient, chlorophyll c3 was quantified using the same calibration as for 132 m . vernet tuhle 2 fluorescence maxima of pigmen15 analyaed b) reverse-phase high-performance liquid chromatography obtained from thcir fluorescence cxcitation \pectra peak numbers as s h w n in fig 2 spectra o f the pigments were measured in the eluent in a row-through cell attached to the 5pectrofluorometcr. peak pigmcnc retention fi uorescence number time ( m i n ) maxima ( n m ) i 3 4 > h 7 x i 0 11 c'hloroph\ll r dcribalivc chlorophyllide o chloroph>ll c phaeophorbidc a-like (a:) phaeophorbidc d l i k e ( a , ) phaeophorbidr a-like ( a , < ) chlorophyll q + c derivatives chlorophyll u derivative chlorophyll u phaeophytin a-like ( a , ) phaeophytin a-like ( a l ) h y x 0 x y 9 5 10.4 12.1 14.0 14.6 15.0 l y . 5 11.0 chlorophylls c , even though a large error might be expected using this approach (jeffrey & wright 1987). photooxidation estimates of phaeopigments were obtained using material collected in the 100 m traps in june 1987. samples from the traps were diluted with filtered seawater. shaken t o homogenize. and incubated in 250ml pyrex bottles. eight bottles were exposed t o sunlight in an incubator placed o n deck. temperature was kept at 0 % 1°c with running seawater from the ship's water intake. o n e bottle was wrapped in aluminum foil and kept in the refrigerator. in the dark. at 2"c, as control. the pigment content was measured at 3. 6 . 12. 24. 36. and 48 hours of incubation. photooxidation constants. k , . were calculated as in welschmeyer & lorenzen (1985). phytoplankton growth and zooplankton graz ing were estimated from pigment budgets. in the summer cruise of 1988. steady state was assumed and the simplified equations presented in welsch meyer & lorenzen (1985) were used. chlorophyll sedimentation from the euphotic zone was not assumed to be zero. and was estimated as c , c-', where c , (mg chl a m-' d i ) is the chlorophyll flux to the sediment traps and c (mg m-') is the integrated chlorophyll in the euphotic zone. in the spring of 1987. during the bloom. equations were solved numerically. including chlorophyll sedimentation from the euphotic zone and accounting for changes in the depth of the euphotic zone as expressed in laws et al. (1988). pigment concentration was integrated to the 454. 585 437. 624. bb5 450. 586,634 425. 666 414. 614. 662 4ox. h24. 666 442. 462. 626. 667 435. 624. 666 435. 626. 667 117 5. 667 417 5, 666 depth of 1 % incident radiation, defined as the depth of the euphotic zone. pigment estimated by the turner designs fluorometer was used for this analysis because h p l c data for water column phaeopigments were not available for june 1987. results h y d r o g r a p h y . spring c o n d i t i o n s two stations were visited during the spring of 1987 (fig. 1). stns. 947-987 were situated in atlantic waters during a bloom of phaeocystis p o u c h e t i i . with chlorophyll a concentrations of 4 to 6 mg m-3 from the surface to a depth of 60 to 80 m. at this station stratification was very weak, nitrate was detectable through the mixed layer, and the euphotic zone (1% isolume p a r ) extended t o 18 m (wassmann et al. 1991). stns. 941-994 were located in an area under the influ ence of the polar front (rey & loeng 1985) and close to the ice edge. stn. 941 was similar t o stn. 947 but with only 1.3 mg chl a m-3 in the t o p 20 m of the water column. t e n days later, at stn. 994, a strong subsurface chlorophyll a maximum had developed at 4 3 4 5 m . at the depth of a strong halocline. d u e t o surface meltwater. nitrate was depleted in the mixed layer and t h e depth of 1%' isolume ( p a r ) was 41 m . chlorophyll a con centrations averaged 0.5 mg m-3 in the mixed layer and peaked at 12 mg m ' at the maximum. this temporal variability in the chlorophyll profile phytoplatiktori d y n m i c s in the barents sea 133 like pigments were found consistently in the water column and sediment traps (fig. 3). the nomenclature corresponds t o vernet & lorenzen (1987) also used by downs (1989) and hurley & armstrong (1990). two phaeopigments, not named in vernet & lorenzen (1987), less polar than phaeophorbide a 3 , were named a4 and a 5 , as in downs (1989). phaeophorbide a5 was not always well resolved from a4, the most abundant of the two pigments ( p e a k 6 in fig. 3). phaeo phytin a l and a2 ( p e a k s 10 and 11 in fig. 3) were present in all samples. a third minor form eluted after a l , but was not quantified. i present here quantification of t h e more abundant phaeo phorbideand phaeophytin-like pigments, a 2 , a 3 and a 4 + 5 and a , and a,, respectively. suggests strong advection in the area (wassmann et al. 1990), precluding the use of the pigment budget model at this station. summer conditions the stations visited in july 1988 were located in atlantic waters (fig. 1) and had already experi enced &he spring bloom. of the two, stn. 885 had a deeper mixed layer (30 m), and a lower density gradient at the pycnocline (wassmann et al. 1991). nitrate concentrations were undetectable throughout the mixed layer and a nutricline was established between 20 and 75 m. chlorophyll a concentrations were 0 . 9 m g m-3 in the mixed layer and had a subsurface maximum of 1.6mg n r 3 a t the t o p the nutricline, a t a depth of 30 m, with a secondary maximum a t 6 0 m (fig. 2d). this station presents characteristics of late bloom conditions in the barents sea when phyto plankton distribution changes from high con centration in the mixed layer to a d e e p chlorophyll maximum at the nutricline (thingstad & mar tinussen 1991 this volume). station 864, further north, had a shallower mixed layer (20 m) and a stronger density gradient than stn. 885. tem perature profiles revealed a warming of surface waters (5°c) over colder water (2.7"c). nitrate concentrations were also undetectable at the mixed layer. a nutricline was present from 50 to 100m (wassmann e t al. 1991). chlorophyll a concentrations were low in the mixed layer (0.2 mg m-3) and peaked at about 75 m with a concentration of 1.2 mg m j at the depth of maxi mum nutrient gradient (fig. 2d). this station represents summer, or postbloom, conditions in the barents sea (thingstad & martinussen 1991). the euphotic zone, calculated as the depth of 1% isoline for p a r , extended t o 37 and 2 5 m for stns. 864 a n d 885, respectively. while the chlorophyll maximum during the late bloom was at the bottom of the euphotic zone (stn. 885), the chlorophyll maximum in the postbloom (stn. 864) was well below the 1% isolume for p a r (fig. 2a and d). although the exact position of the chlorophyll a maximum might have been lost due to low resolution in the sampling (depths sampled were only 50,75 and 100 m), it was situated below the 0.1% isolume for p a r (55 m). phaeopigment diversity five phaeophorbide-like and three phaeophytin pigments in seston the vertical profile of accessory chlorophylls fol lowed that of chlorophyll a (fig. 2 a and d). the abundance of chlorophylls c1 +, and c3 at station 885 during the late bloom suggests a dominance of diatoms over prymnesiophytes (jeffrey & wright 1987). t h e ratio of chlorophyll c3 :chlorophyll c 1 + 2 (w/w) integrated over the t o p 1 0 0 m was 0.1. stn. 864 was dominated by chlorophyll ci containing algae, probably prymnesiophytes (jeffrey & wright 1987). t h e ratio of chl c3:chl cl+2 (w/w) in the upper 100 m was 0.91. a ratio of approximately 1.0 is commonly found in cul tures of prymnesiophytes, suggesting that most of the chl c 1 + 2 is mostly c 2 from the prymnesio phytes. deeper in the water column, a t the depth of the chlorophyll a maximum, chlorophyll c , + ~ become more abundant, suggesting more diatoms at the nutricline. vertical distribution of phaeopigments was similar to that of chlorophyll a. maximum con centrations coincided with the chlorophyll a maxi mum at both stations although a t stn. 885 the deep maximum ( 6 0 m ) was more conspicuous than the shallow o n e (30 m). phaeophorbide a 4 + 5 was the most abundant phaeopigment in the euphotic zone at both stations, followed by a2 and a,. below the euphotic zone, the stations differed. at stn. 885 phaeophorbides a3 and az became more abundant while phaeophorbide a 4 + 5 stayed dominant in the postbloom situation (stn. 864). phaeophytins presented a similar distribution t o that of the phaeophorbides (fig. 2c and f ) but were more abundant during post-bloom con 134 m. vernet ditions (stn. 864). phaeophytin a , was generally more abundant than phaeophytin a,. pigment sedimentation the two stations in july of 1988 presented dif ferent patterns of sedimentation for chlorophylls and phaeopigments (table 3 ) . phaeopigment sedimentation (all forms of phaeophorbide and phaeophytin combined) was always higher than chlorophyll a sedimentation for any given depth sampled. during the late bloom (stn. 885) chloro phyll a sedimentation was maximum at 40 and 9 0 m and decreased at larger depths. phae opigment sedimentation was lower at 4 0 m and was higher at 9 0 m and deeper. a t stn. 864, during postbloom conditions, sedimentation of all pigments increased 5-fold from 60 to 100 m . t h e 0 25 ci e 5 so 8 0 75 100 ~rr.di.nc~ (ein.1 mead") 1 . 1 . - 0.0 0.6 1 .o 1 .s 2.0 chl-. (rqa chl-c (!ae/l) l . l . l ' ' . j 0.0 0.6 1 .o 1 .s 2.0 1 . 1 . " 0.0 0.6 1 .o 1 .s 2 .o chl-cj (rq/l) similar pattern of both chlorophyll u and phaeo pigments suggests that t h e chlorophyll a maxi mum at about 75 m was the main source of sedi menting matter a t this station. sedimentation rates of phaeopigments showed different patterns among pigment forms and sta tions (table 3 ) . phaeophorbide a 3 was the most abundant degradation product in sediment traps. the only exception was a t 60 m at stn. 864 where phaeophorbide ad+ 5 showed the highest sedi mentation rate. phaeophorbide a? had maximum sedimentation rates in the t o p 100 m during late bloom conditions. with decreased sedimentation rates with depth, while the opposite was observed in postbloom conditions (stn. 864). phaeo phorbide u 3 had maximum rates of sedimentation at 90 or 100 rn. a t greater depths, t h e pattern of sedimentation differed for both stations. remain 0.00 0.03 0.06 0.09 0.12 0.15 phbld. 2 i rga) a-a-4 phbld. 3 (llg/l) tf. 1 . 1 . 1 . . . i , j 0.00 0.03 0.06 0.09 0.12 0.16 1 . 1 . 1 . ~ . 1 , 0.00 0.03 0.06 0.09 0.12 0.15 phb4+6 ( pa/l) fig. 2 . vertical profiles of pigments from 0 to 100 m at two stations in the barents sea visited during july 1988. pigments were analysed by hplc. lrradiance (thick line) is shown for each station i n ( a ) and (d). phytoplankton dynamics in the barents sea 135 0 25 i ci e g 50 0 a 75 100 0.00 0.02 0.04 0.06 0.08 0.10 phytln 1 (up/i) a 4 a 0.00 0.02 0.04 0.00 0.08 0.10 phytln 2 ( p g / l l tt. 0 25 i e 5 50 8 a 7 5 100 0. i f i ' i * ' i i 1 , i \ > 0.09 0.06 0.00 0.12 0.15 phblda 2 ( p g / l ) c-ci 1 l l , l , , , , , , 0.00 0.03 0.06 0.09 0.12 0.15 phbld. 9 (pg/i) tt. i . i i l , i . i , l 0.00 0.03 0.06 0.00 0.12 0.15 0 25 1 e 5 50 a a u 0 7 5 ty st.885 i i 100 i , i , / , , , 6 8 10 0 2 4 irradlanco (elf181 m-* d-'i-- 0.0 0.5 1 .o 1.5 2.0 chl-8 ( pga) l i i . l , i i 0.0 0.5 1 .o 1.5 2.0 chi-c ( pg/l) i i i i 1 , i i 0.0 0.5 1 .o 1.5 2.0 ch1-d ( pg/l) 0 2 5 e 5 5 0 a e 0 u 7 5 100 -- 0.00 0.02 0.04 0.06 0.08 0.10 phytln 1 (sg/l) 0.00 0.02 0.04 0.06 0.08 0.10 pmd. 4+6 ( pa/l) phytln 2 ( p g / l l 0-0-0 136 m . vernet 5 10 15 20 25 time (rnin) f i g . 3. chromatogram zhouing chloroph>ll a and chlorophyll degradation products from 3 5edirnent trap sample collected i n july 1988 in the barents sea pigments were analyscd with a reverse-phase hplc and detected by ruorcscence with exci tation wave length at 42onrn and emission at 680nm. peak identities correspond to those in table ?. ing high at stn. 885 while decreasing at stn. 864. phaeophorbide a.,, increased their sedimen tation rates with depth. with the exception of 100m at stn. 864 where rates peaked. sedi mentation rates of phaeophytin a ? , the form least abundant in the water column. were always equal to or larger than those of phaeophytin a , . t h e pattern of sedimentation of the 2 phaeophytins was similar t o that of phaeophorbide ~ 2 . in general, maximum rates of sedimentation were found at 90 and 100 rn at stns. 864 and 885 respect ively, immediately below the depth of the pigment maxima, where diatoms were more abundant. phaeopigment photoxidation rates the results from the 3 experiments were com bined and the resultant first o r d e r photooxidation decay constant, k , (m? mol-i) was computed. photooxidation rate constants vary among the individual chlorophyll degradation forms by a factor of 2 . from 0.009 to 0.015 m' mol-l (fig. 4 ) . the average photooxidation rate constant for all pigment combined (sum p h a e o ) was 0.012 m' mol-'. pigment model the estimations of phytoplankton growth rate and zooplankton grazing during spring and sum mer based on the pigment model of welschmeyer & lorenzen (1985) a r e shown in table 4. phyto plankton during the bloom of phaeocystis pou chrtii i n atlantic waters, not influenced by the polar front, grows at an average rate in the euphotic zone of 0.14-0.17 d ' . macrozooplank ton grazing ( 0 . 0 5 4 . 0 6 d ' ) dominated over microzooplankton grazing (0.01-0.02 d i ) , accounting for approximately 35% of the phyto plankton loss. sinking of intact cells out of the euphotic zone. estimated from the sedimentation rate of chlorophyll a , was 7-8% of the growth. between 45 to 50% of the newly formed chloro phyll accumulated in the euphotic zone. when compared to growth rates estimated from i4c incorporation, assuming a c : chla ratio of 75 from the p o c data ( f . rey, unpubl. data) and growth calculations according to eppley (1972), the model underestimated phytoplankton growth by 3 5 % . d u e to the lack of independent estimates of the phytoplankton c : chla ratio, it is not poss ible to determine how much pigment might have been lost during grazing (i.e. lopez et al. 1988). a loss of 33% though is expected during macro lankton grazing (downs 1989) and seems t o be a representative pigment loss term in the spring bloom (laws et al. 1988). estimates of phytoplankton growth rates for the summer were a n order of magnitude lower than for spring (table 4). macrozooplankton grazing rates were also an o r d e r of magnitude lower than in the spring. while microzooplankton grazing rates were about the same. in late bloom conditions (stn. 885), where diatoms dominated in the water column, microand macrozooplank ton grazing were comparable. t e n percent of the chlorophyll sank out of the euphotic zone and about 8% still accumulated. in postbloom con ditions, where small flagellates were dominant, microzooplankton grazing accounted for 85% of the phytoplankton growth, while 7 % sank o u t of the euphotic zone, and there was almost no net accumulation of phytoplankton in the euphotic zone. n o radiocarbon incorporation data a r e available from this cruise in o r d e r t o compare growth estimates. discussion arctic phytoplankton phytoplankton growth at the ice edge of polar regions is characterized by a n intense growth phytoplankton dynamics in the barents sea 137 table 3. biomass and sedimentation rates of chlorophyll a and its main degradation products during july 1988. pigments were analysed and quantified by hplc. pigment identification as i n table 2 and fig. 2. "sum phaco" dcnotcs total phacopigment. pigment biomass was integrated from the surface to the depth of the euphotic zone. scdinicntation rates were calculated without correction for daily losses, estimated to be < 2 % d ' (wassmann et al. 1991). pcrcentage loss wa5 estimated as (sedimentation x 100/biomass) in units of d ' . station pigments 864 phbide 2 phbide 3 phbide 4 + 5 chi a phytin 1 phytin 2 sum phaeo phbide 2 phbide 3 phbide 4 + 5 chl a phytin 1 phytin 2 60 0.45 0.42 0.90 13.67 0.86 3.11 i00 i .29 2.85 4 09 54.83 2.83 2.22 0.48 0.1 0.3 1.2 2.5 0.2 0.2 2.0 24.3 7.0 15.9 2.5 4.5 2.0 0.22 0.71 1.33 0.18 0.42 0.64 i .55 8.53 1.71 0.29 0.88 2.03 0.23 sum phaeo 13.28 40.3 303.0 phbide 2 230 1.29 1 .x 1.40 phbide 3 phbide 4 + 5 chl a phytin 1 phvtin 2 2.85 5.8 4.09 4.0 54.83 2.5 2.83 1 . 1 2.22 i .4 2.04 0.98 0.05 0.39 0.63 885 sum phaeo 13.28 21.7 163.0 phbide 2 40 0.94 1.7 181 phhide 3 0.71 5.5 7.75 phbide 4 + 5 i 3 9 3.2 2.01 chl a 38.11 7.2 0.19 phytin 1 0.97 0.8 0.82 phytin 2 0.87 1.7 1.95 sum phaeo 5.08 12.9 253.0 phbide 2 90 3.01 1.8 0.60 phbide 3 3.20 14.9 4.66 phbide 4 + 5 3.08 3.9 1.27 chl a 47.9 6.8 0. i4 phytin i 1.95 1.5 0.77 phytin 2 1.66 3.8 2.29 sum phaeo 12.99 25.y 109.0 phbide 2 150 3.01 1 .0 0.33 phbide 3 3.20 13.9 4.34 phbide 4 + 5 3.08 6.0 1.95 chl a 47.95 2.9 0.06 phytin 1 1.95 1.1 0.56 phytin 2 1.66 1 .9 1.14 sum phaco 12.99 23.9 184.0 phbide 2 200 3.01 i .0 0.33 phbidc 3 phbide 4 + 5 chl a phytin i phvtin 2 3.20 47.95 i .95 1.66 3.08 sum phaco 12.95, phbide 2 250 3.01 phbide 3 phbide 4 + 5 chl a phytin 1 phytin 2 sum phaeo 3.20 3.08 47.95 1.95 i .66 12.99 17.6 7.8 2.3 0.8 1.4 28.6 0.7 15.3 7.2 2.5 0.9 1.1 25.2 5.50 2.53 0.05 0.41 0.84 220.0 0.23 4.78 2.34 0.05 0.46 0.66 194.0 138 m . verne1 a .. phbide 4 o.00t . a e . i a = 0083 j -3 00 0 40 80 120 160 (rn2einst . 1 ) phytin 2 o.00t = i hm e l r 2 = 0 4 9 a = 4 3 1 -1.00 -3.00 0 40 80 120 160 (m2einst -l ) phbide 3 o . o o t 0 3 r z = 0 8 5 a = 4 3 1 a -3 00 0 40 80 120 1 i0 (rn2eins.t -l ) phytin 1 o . o o t * . 1 j k = 4 0 1 r’= 069 -3 00 0 40 80 120 160 (rn2einst-’ ) sum phaeo 0.00 0 a = a.z? -. ., 0 40 80 120 i s 0 (m‘einst -‘) period during the spring d u e to increased sta bilization of the water column. sun angle and daylength ( d u n b a r 1981; rey e t al. 1987; nie bauer & alexander 1989; sakshaug 1989). in the arctic, and in particular in the northern part of the barents sea, the bloom crashes after nitrate has been stripped from the mixed layer and marks the onset of the summer period which is charac terized by a subsurface chlorophyll a maximum near the nutricline. t h e stratification of water is fig. 4. estimation of photooxidation rate constants for the chlorophyll degradation products abundant in the water column and sediment trap matter. data include three experiments incubated on deck in june 1987 from material collected in 100-m traps at stns. 941-994 and 947-987. temperature was maintained at 0 ? 1°c with running seawater from the ship’s intake. peak 4 is a mixture of phaeophorbide (i,+%. sum phaeo ( f ) is the average photooxidation rate constant for all the phaeopigments combined. either d u e t o ice melting at t h e ice edge or t o warming of surface layers, as in t h e case of atlan tic waters in the southwestern a r e a of the barents sea (skjoldal e t al. 1987; loeng 1989). winter and summer are generally dominated by small flagellates while spring blooms a r e d u e t o either diatoms and/or phaeocystis poucherii (rey e t al. 1987). while diatoms a r e generally present in the atlantic waters of the barents s e a , p . pouchetii is dominant in ice edge blooms (wassmann e t al. phytoplankton dynamics in the barents sea 139 table 4. results from pigment model as in wclschmeyer & lorenzen (1985). stations durmg may/june 1987 wcrc solved numcrically. accounting for changes in mixed layer depth and accumulation of biomass in thc euphotic zonc, 3 s in laws ct al. (1988). stations in july 1988 were assumed to be in steady state and solved as in wclschmeyer & lorcnzen (1985). primary production measurements were used to estimate phytoplankton growth rate according to epplcy (1972) and using thc carbon: chlorophyll ratio estimated from particulate (poc) data*. stations 896/911/994 in may/june 1987 wcrc not considcrcd due to lateral advection present at the stations. macro and micro refer to macrozooplankton and microzooplankton; sinking is an estimate of sinking rate of intact cells as indicated by the scdimcntation rate of chlorophyll a , accum refers to the fraction of phytoplankton growth that remains in the euphotic zonc. station zooplankton phytoplankton mass balance *phytoplankton grazing growth growth ( d ' ) ( d ' ) ( d ' ) macro micro macro micro sinking accum july 1988 864 0.0024 0.0309 0.036 7% 85% 7%' 1% 885 0.0059 0.0087 0.018 33% 49% 10% 89% may 1987 947 (11) 0.06 0.02 0.17 34% 13% 8% 45% 0.2 987 (12) 0.05 0.01 0.14 36% 7% 7% 50% 0 1 8 1990), either after a diatom bloom, when silicate becomes limiting for diatoms, or from the onset of the bloom. similar observations have been made in the greenland sea (cota et al. 1990) and in the waters around iceland (stefansson & olafsson 1990). diatoms were dominant in the blooms of atlan tic waters in june of 1987 (vernet unpubl. data) and during late-bloom conditions in july of 1988 (stn. 885). single cell prymnesiophytes (i.e. emi liana huxleyi) were present in pre-bloom con ditions in may 1987 (vernet unpubl. data) and increasingly dominant from late-bloom to post bloom in july 1988 (stn. 864). at the ice edge in may-june 1987, more than 95% of the plankton consisted of p . pouchetii cells (c. hewes, pers. comm.). the distribution of accessory pigments gave a good approximation to characterizing these phytoplankton assemblages in the barents sea (fig. 2 ) . plankton dominated by diatoms were rich in chl c , + ~ (stauber & jeffrey 1988), while those with prymnesiophytes such as e . huxleyi and p . pouchetii had chl c3 in addition to chl c2 (jeffrey & wright 1987). with respect to car otenoids, e . huxleyi has 19' hexanoyloxyfu coxanthin as the main carotenoid (vernet 1989). diatoms and p . pouchetii have focuxanthin (wassmann et al. 1990). the difference in dom inant carotenoid within the prymnesiophytes makes it possible to differentiate them. large cells such as diatoms and the colonial form of p . pouchetii dominate the spring bloom, at which time there are shallow mixed layers, nitrate is present in measurable concentrations, and the density stratification is weak. on the other hand, small flagellates characterize deep or nutrient-depleted mixed layers, encountered in either preor postbloom conditions. in this study, large diatoms were abundant in late spring (stn. 885) but were displaced by prymnesiophytes in the mixed layer as nitrogen became low. these diatoms still grew at the depth of chlorophyll maximum in summer conditions (stn. 864), when irradiance was low but rates of nutrient supply were probably high. this scenario supports the hypothesis that large cells can grow in environ ments where there is an increase in the rate of nutrient supply (thingstad & sakshaug 1990). chlorophyll degradation the more abundant forms of chlorophyll a degra dation found in seston and sedimenting particles of the barents sea (see fig. 2 ) are similar to the forms found in temperate coastal marine waters (klein & sournia 1987; vernet & lorenzen 1987; downs 1989; roy & poulet 1990), lakes (car penter et al. 1986; hurley & armstrong 1990) and sediments (brown et al. 1977). the uniformity of components suggests common catabolic pathways in aquatic environments (hendry et al. 1987). in arctic waters, as in other areas of the ocean, the main pathways of chlorophyll degradation involve biotic and abiotic factors. oxidizing and non oxidizing enzymes from either the alga itself or a grazer that has ingested it, light, bacterial activity, and oxygen are the main degradative agents (hendry et al. 1987). the last two sources can be 140 m . veriier considered secondary in short periods of time (downs 1989; roy & poulet 1990). particularly in polar waters (wassmann e t al. 1991). in the euphotic zone, light plays a main role in the degradation of chlorophyll and phaeopigments associated to detritus. pigments a r e degraded to colorless compounds (struck et al. 1990). the main product of photooxidation (soohoo & kie fer 1982; welschmeyer & lorenzen 1985; vernet & lorenzen 1987; downs 1989). in the absence of light, below the euphotic zone. enzymatic activity resulting from zooplankton grazing may be the main factor of chlorophyll degradation. activity from cellular enzymes. such as chlorophyllase. dephytylizes chlorophyll a in diatoms (jeffrey & hallegraeff 1987). from chlorophyllide further enzymatic activity has been found to produce pyropheophorbide via phaeophorbide in cultures of chlorella fusca. pyrophaeophorbide. the end product, was found to be very stable in the dark and thus accumulated (ziegler e t al. 1988). it is clear that further studies are needed in order to characterize the different forms of phaeophorb ide-like molecules and other degradative forms (matile et al. 1989). the constancy of the mol ecules analyzed, common to so many environ ments, justify the effort. photooxidation rates of chlorophyll degr2. dation seem to follow first-order kinetics (soohoo & kiefer 1982; welschmeyer & lorenzen 1985). at o'c, photooxidation rates of individual phae opigments vary by a factor of 2 (fig. 4a-d). in the barents sea. phaeophorbide a 3 had the highest rate of photooxidation, followed by phaeophorbide a! and phaeophorbide a , . t h e lowest rates are associated with the less polar forms, phaeophorbides a,,,. both forms of phaeophytins also had lower rates than the more polar phaeophorbides. downs (1989) found the same differences among phaeophorbides a 2 and a 3 , although the constants were, on the average. 3 to 5 times higher. a n important corollary of the difference in photooxidation rates of phaeopigments is that the distribution of phaeopigments in the euphotic zone has to be interpreted in light of these differences. where the abundance is a function of the balance between production and loss rates. distributions depicted in fig. 2 and photooxidation rates in fig. 4 suggest that phaeophorbide a,, can accumulate twice as fast as phaeophorbide a 3 for a similar production rate. and may account in part for their abundance in the euphotic zone. total photooxidation rate can be calculated as the decay rate of the corn bined pigments (fig. 4 f ) . for a more accurate calculation of the photooxidation rate of the whole phaeopigment assemblage we should include the relative contribution of each indi vidual component. photooxidation rates measured in this study at 0°c are lower than previously published data for temperate waters (soohoo & kiefer 1982; welschmeyer & lorenzen 1985; downs 1989) and support the hypothesis of temperature depen dence. welschmeyer & lorenzen (1985) and downs (1989) found photooxidation rates to be independent of temperature. t h e authors suggest that the source and type of phaeopigment are a probable cause of the variability observed. t h e rates measured in this study suggest otherwise. individual rates of phaeopigments measured by hplc and the combined photooxidation constant show lower degradation rates at lower tem peratures. fig. 5 shows a n arrhenius plot includ ing all the published k, values from marine environments where temperature has been measured. they have been converted t o units of m' mol-' (table 5). t h e regression obtained is similar t o the o n e by soohoo & kiefer (1982). about 35% of the variance is still unexplained suggesting that other variables, such as type of light sensor, type of dominant form of phae opigment, calibration of the fluorometer, incident a = 4 7 7 r2= 0% ~ 3.3 3.4 , 3.5 3.6 3.7 rn i 0.01 + 10 -3(ak-1) t fir. 5 . arrhenlus plot of the photooxidation rate constant as a function of temperature. estimates from marine waters have hcen pooled: (solid squarc) soohoo & kicfer (19x2): (cross) wclschrncyer & lorenzen (1985): (open square) downs (19x9): (triangle) vcrnct & mitchell (19yu): (asterisk) this study. tem perature range from -0" to 28°c (see table 4). statistics and \driancc cxplaincd arc similar to those ohtaincd by soohoo & kicfcr (19x2). phytoplankton dynaniics i n the barerits sea 131 table 5 . summary of the first order photooxidation decay constant of phaeopigmcnts source k , . 10.' substratc (m'/einst) ~~~ ~ temperature ~ ~ soohoo & kiefcr (1982) welschmeyer & lorcnzcn (1985) barents sea (this study) vernet & mitchell (1990) downs (1989) 1.1-8.8 scston fecal pcllcts 6.75 scston 1.20 sediment trap 1.87 scdiment trap 3.693.9 scdimcnt trap & 2 8 t -y-?vc -1-+2"c 1-+2"c 1+21"c spectral irradiance, and probably size of the par ticles containing phaeopigments, can introduce uncertainty in this type of measurement. the lack of a significant temperature dependence in photooxidation rates in welschmeyer and lorenzen (1985) and downs (1989) studies may be due t o the narrower range of temperatures studied and the logarithmic relationship between these 2 variables. accurate values of photooxidation rate con stants become increasingly important at lower temperatures. a sensitivity analysis showed that the total contribution of microzooplankton graz ing to total grazing in the pigment model decreases rapidly at lower values of k, (fig. 6). the model is then most sensitive for low photo oxidation rate constants, in the range of values measured for arctic waters. specific forms of chlorophyll degradation seem to be quantitatively related to the type of phyto 0.21 8.100 ' 0.02 ' 0.04 ' 0.06 ' 0.08 ' 0.io k , (m2 einst-') fig. 6. temperature dependence of photooxidation ratc con stant in the pigment budget model (welschmcyeer & lorenzen 1985): scnsitivity analysis of the contribution of micro zooplankton grazing (g) to total grazing (g + g') as a functlon of the photooxidation rate constant ( k , ) , arrows indicatc three photooxidation ratc constants: this study (0.012 m2einst-'). soohoo & kiefer (1982) (0.037 m'einst-') and wclschmeycr & lorenzen (0.0675 m?einst-'). plankton present. phaeophorbide was more abundant in the station dominated by prym nesiophytes while phaeophorbide a3 was pro duced by degradation of diatoms. it is not possible to differentiate with the present sampling design if the degradation is originated by enzymes in the phytoplankton or in the grazers if we assume a close coupling between phytoplankton groups and types of grazers. t h e dominant form of phaeo phorbide related to the pair alga-grazer is present not only in the seston but also in the large particles that sink out of the surface and are caught by the sediment traps. if, as hypothesized by shuman (1978) and welschmeyer & lorenzen (1985), phaeopigments in t h e seston a r e mainly d u e t o microzooplankton grazing while sinking faecal pellets originate mainly from macrozooplankton, the dominance of the same phaeopigment both in the water column and sediment t r a p sug gest that the pathway of chlorophyll degradation is related more to the alga than t o the grazer. sedimentation of the most abundant phae ophorbide a in lakes was d u e t o the presence of large grazers (laevitt & carpenter 1990) pre sumably feeding on large algae. pigment sedimentation pigment sediment out of the euphotic zone by either direct sinking of phytoplankton cells, phy todetritus, or through zooplankton fecal pellets. intact phytoplankton cells contain almost exclus ively non-degraded chlorophyll a pigments while the pigments of faecal pellets a r e mostly phaeo pigments (but see wassmann et al. 1990). never theless some undegraded chlorophyll a in the sediment traps could originate from faecal pellets (vernet & lorenzen 1987). in this way, estimates of cell sinking based o n chlorophyll a sedi mentation rates would b e maximum. maximum sedimentation rates of phaeopig 142 m . vernet ment measured below the chlorophyll maximum at both stations suggest that most of the defecation of pigments occurred while zooplankton were feeding at the chlorophyll maximum, as shown by welschmeyer et al. (1984) and dagg et al. (1989) i n coastal areas. if the active transport of pigments by zooplankton to depth through vertical migration is minimum (dagg et al. 1989), sedi mentation rates at depth are dependent mostly of the remineralization or reingestion of pigments by other plankton at mid-depth. the higher changes observed from 100 to 230 m at stn. 864 suggest higher recycling of sinking organic matter in the summer with respect to late spring (from 90 m to 250m at stn. 885). the constant sedimentation rate of pigments below 150m at both stations (except phaeophorbide a 3 ) indicate that most of the transformation may occur immediately below the maximum pigment flux. although all forms of phaeopigment were found at all stations, there seems to be a quan titative relationship between some phaeo phorbides and the type of phytoplankton. phaeo phorbide a3, with high and constant sedi mentation rates below 100111, seems to be associated to large particles that sink fast and are not recycled at mid depths. these results agree with higher presence of this pigment in seston associated with larger cells, i.e. diatoms, at the chlorophyll a maxima at both stations. phae ophorbide a,,+ is proportionally more abundant where prymnesiophytes dominate, at stn. 864, but it is also related to fast sinking particles, particularly at stn. 885. in general, mid-water recycling seems to be more important at stn. 864. during summer conditions, although a lack of sampling at intermediate depths makes these con clusions tentative. phytoplankton population dynamics the rate of phytoplankton growth estimated by the pigment budget model during the spring (stns. 947 and 987) is about 65% of the estimate using radiocarbon incorporation. these numbers are within what is expected if we assume a pigment conversion efficiency of about 65% from a large phytoplankton to a large grazer (shuman & lor enzen 1975; welschmeyer & lorenzen 1985; laws et al. 1988; downs 1989). these numbers seem to indicate that chlorophyll budgets are good indicators of phytoplankton dynamics dur ing spring bloom. on the other hand, phyto plankton growth rate estimates for summer sta tions at the barents sea (stns. 864 and 885) are lower than might be expected for phytoplankton growing at high irradiance in stratified waters. growth rates estimated from primary production measured in the same area in june-july 1979 (ellertsen et al. 1982). and assuming a c:chla ratio of 100. are in the order of 0 . 0 6 4 . 1 d-l, 2 to 10 times higher than the estimated rates (table 4). similar discrepancies are observed in tropical environments. laws et al. (1988) suggest that phytoplankton growth rates in the central pacific might be underestimated by 6670 if we compare data from the pigment model (welschmeyer & lorenzen 1985) to the direct measurements of growth rate (laws et al. 1987). both tropical and arctic data indicate that where nutrient recycling is important and where small algae and small grazers are dominant, there is a higher loss factor in the conversion of chlorophyll t o phaeopig ments. an alternative scenario could be that the observed phaeopigment :chlorophyll ratio would be averaged over a longer food web each of them with a 35% loss in each step of the food web. independent of the reason, summer situations in the arctic seem more similar to tropical stations with an average conversion factor larger than 66%. these results are thus in agreement with studies where pigments were useful tracers of macrozooplankton grazing (dagg et al. 1987) while the opposite is true for microzooplankton (klein et al. 1986; strom 1988). during the spring bloom, phytoplankton grew at maximum growth rates for the ambient light and temperature present at that time of year. growth rate estimates of 0.14-0.17 d-l in 1987 were calculated based on a mean irradiance in the euphotic zone of 1.6611101 m-' d-'. planktonic diatoms isolated from the barents sea, grown at 18 pmol m-2 ski of continuous light (total daily mean irradiance of 1.55mol m-* d-l), had an average growth rate of 0.17 d-' (gilstad & sak shaug 1990), in good agreement with the model estimates. in conclusion, estimates of phytoplankton dynamics based on chlorophyll budgets can be used with reliability during ice edge blooms of arctic waters. during summer conditions the model seems to underestimate phytoplankton growth. mass balances of c are within expected values during both seasons, although the mag nitude of any given pool must be underestimated during the summer. the model parameters used phytoplankton dynamics in the barents sea 143 for temperate and tropical waters cannot be directly applied to polar areas, in particular the photooxidation rate constant for phaeopigments. a close look at the individual phaeopigments in the water column and sedimenting matter can give insight into phytoplankton-grazer inter actions. furthermore, information on phyto plankton composition based on distribution and abundance of accessory pigments can relate graz ing to food availability. acknowledgements. i thank p. wassmann for the sediment trap samples, f. rey for primary productivity data. h.-r. skjoldalfor shiptime, g. johnsen for hplc analyses, e. brody for data analysis and graphics, e. sakshaug for financial support, and e. sakshaug, p. wassmann and b. g . mitchell for critical review of the manuscript. this study was supported by nsf grant dpp-8520848 and by the norwegian research council for science and humanities (navf). references bathmann, u. & liebezeit, g. 1986: chlorophyll in copepod faecal pellets: changes in pellet numbers and pigment content during a declining baltic spring bloom. p.s.z.n.i.: mar. ecol. 7, 59-73. bjflrnland, t., guillard. r. r. l. & liaaen-jensen. s . 1988: phaeocystis sp. clone 677-3 a tropical marine planktonic prymnesiophyte with fucoxanthin and 19’-acycloxyfuco xanthins as chemosystematic carotenoid markers. biochem. syst. ecol. 16, 445-552. brown, j. s. 1985: three photosynthetic antenna porphyrins in a primitive green alga. biochem. biophys. acfa 807.143-146. brown, s. r., daley. r . j . & mcneely, r. n. 1977: com position and stratigraphy of a fossil phorbin derivatives of little round lake. ontario. limnol. oceanogr. 22,336348. chisholm. s. w., olson, r. j., zettler, e. r.. goericke, r.. waterbury, j. b. & welschmeyer, n. a . 1988: a novel free living prochlorophyte abundant in the oceanic euphotic zone. nature 334, 340-343. carpenter, s . r., elser, m. m. & elser. j . j. 1986: chlorophyll production, degradation and sedimentation: implications for paleolimnology. limnol. oceanogr. 31, 112-124. conover, r. j . . durvasula. r., roy, s. & wang, r . 1986: probable loss of chlorophyll derived pigments during passage through the gut of zooplankton. and some consequences. limnol. oceanogr. 3 1 , 871887. cota, g . f., smith, w. 0. & mitchell, b. g . 1990: photo adaptation of phaeocysfis near the ice edge of the greenland sea (cearex). eos 71, 79. currie, r. 1.1962: pigments in zooplankton faeces. nafure 193, 956957. dagg, m. i . , frost, b. w. & walser. w. e . 1989: copepod die1 migration, feeding. and vertical flux of pheopigments. limnol. oceanogr. 34. 1062-1071. dagg, m. j . & walser, w. e . 1987: ingestion, gut passage, and egestion by the copepod neocalanus plumchrur in the laboratory and in the subarctic pacific ocean. limnol. oceanogr. 34, 171188. daley. r. j . & brown, s . r. 1973: experimental charac terization of lacustrine chlorophyll diagenesis. i . physio logical and environmental effects. arch. hvdrobiol. 72. 277 304. downs, j . n. & lorenzen, c . j . 1985: carhon:pheopigment ratios of zooplankton fecal pellets as an index of herbivorous feeding. limnol. oceanogr. 30, 102c1036. downs. j . n. 1989: implications of the phaeopigment. carbon and nitrogen content of sinking particles for the origin of export production. ph.d. thesis, univ. washington, seattle. dunbar, m. h . 1981: physical causes and biological significance of polynyas and other open water in sea ice. pp. 29-35 in stirling, 1. & cleater, h. (eds.): polynyas in the canadian arctic. occm. pap. 45. can. wild. serv. eilertsen, f., hassel, a,, loeng. h.. rey, f.. tjelmeland. s. & slagstad, d . 1982: bkologiske undersokelser n m iskanten i barentshavet somrene 1979 og 1980. fisken og hauet (1982) 3 , 31-83. eppley, r . w. 1972: temperature and phytoplankton growth in the sea. fish. bull. u.s. 70, 10631085. gieskes, w. w. c. & kraay, g. w. 1983: dominance of cryptophyceae during the phytoplankton spring bloom in the central north sea detected by hplc analysis of pigments. mar. biol. 75, 179-185. gilstad. m. & sakshaug. e. 1990: growth rates of ten diatom species from the barents sea at different irradiances and day lengths. mar. ecol. prog. ser. 64, 169-173. guillard, r. r. l., murphy, l. s.. foss, p., liaaen-jensen, s. 1985: synechococcw spp. as likely zeaxanthin-dominant ultraplankton in the north atlantic. limnol. oceonogr. 30, 412-414. hendry, g. a. f., houghton. j. d. & brown, s. b. 1987: the degradation of chlorophyll a biological enigma. new phytol. 107, 255-302. holm-hansen, o., lorenzen, c. j.. holmes. r. w. & strick land, j. d. h . 1965: fluorometric determination of chloro phyll. j . cons. perm. int. expor. mer 30. 3-15. hooks, c. e., bidigare, r. r., keller, m. d. & guillard, r. r . l. 1988: coccoid eukaryotic marine ultraplankters with four different hplc pigment signatures. j . phycol. 24,571 580. hurley, j. p. & armstrong, d. e. 1990: fluxes and trans formations of aquatic pigments in lake mendota. wisconsin. limnol. oceanogr. 35, 384-398. jeffrey, s. w. 1974: profiles of photosynthetic pigments in the ocean using thin layer chromatography. mar. b i d . 26, 101 110. jeffrey, s. w. & hallegraeff, g . m. 1987: chlorophyllase distribution in ten classes of phytoplankton: a problem for chlorophyll analysis. mar. ecol. prog. ser. 35. 293-304. jeffrey, s. w. & humphrey, g. f. 1975: new spectro photometric equations for determining chlorophyll a , b , c , and c2 in higher plants. algae. and natural phytoplankton. biochem. physiol. wanzen (bpp) 167, 191-194. jeffrey, s. w. & wright, s. w. 1987: a new spectrally distinct component in preparations of chlorophyll c from the microalga emiliana huxleyi (prymnesiophyte). biochem. biophys. acta 894, 180-184. klein, b . , gieskes, w. w. c. & kraay. g . w. 1986: digestion of chlorophylls and carotenoids by the marine protozoan oxyrrhis marina studied by hplc analysis of algal pigments. j. plank. res. 8. 827-836. klein, b. & sournia. a. 1987: a daily study of the diatom spring bloom at roscoff (france) in 1985. 11. phytoplankton 197 pp. 113 m . vernet pigment composition studicd h! iiplc dnal!sir ,mar. ecol prog. ser. 3 7 . 2 6 i x landry. m . k . . t l a s x t t . k . p . f a g e r n o s . v. l . . downs. j n & lorenzen. c . j 19x4: effect of food acclimation on dssimilation cfficienc! of caluriiu pac$icus lrmriol. oceuii laws. e . a , . ditullio g k . ti redaljc. d. g . 1987: high phytoplankton growth and production rates in the north pacific subtropical gyre limnol. oceartogr. 3 2 . ws918. laws, e . a , . bienfang. p. k . . ziemann. d. a. & conquest. l d . 1988: phytoplankton population dynamics and the fate of production during thc spring bloom i n auke bay. alaska limnol. oceanogr 3 3 . 57-65, leavitt. p. r . & c a r p e n t e r . s . r . iw: regulation of pigment sedimeniation by photo-oxidation and herbivore grazing c a n . j . fish. a q . scr. 17. llf%1176 loeng. h . 1989: ecological features of the barents sea. pp. 327-365 in rey. l. & alexander. v . ( e d s ): proc. 6rh conf. com. arcrrque fnferriar.. 13-15 m a y 1985. e . j . brill. leiden. lopez. m d g . . huntley. m. e . & sykes. p. f. 1988: pigment destruction by c a l a r t w p a c i f i c w . impact on the estimation of \cater column fluxes j . plarik. res. 10. 715-734. lorenzen. c . j . & downs. j n . 1986: t h e specific absorption coefficients of chlorophyllide u and pheophorbide a in w% acetone. and comments on the tluorometric determination of chlorophyll and pheopigments. lirnnol. o c e a n o g r . 3 1 . 44% 452. lorenzen, c j . . shuman. f. r . 8; bennett, j . t . 1981. i n situ calibration of a sediment trap. lrmnol. o c e a n o g r . 2 6 . 58& 5 8 5 . mantoura. r . f. c . & llewellyn, c . a . 1983: the rapid deter mination of algal chlorophyll and carotenoid pigments and their breakdown products in natural waters by reversc-phasc high-pressure liquid chromatography. a n a l chim. a r i a i s / . 297-31 4. matile. p.. duggelin. t . schellenberg. m.. rentsch. d . bortlik. k . , peisker. c. & t h o m a s , h. 1989: how and why is chlorophyll broken down in senescent leaves? planr physrol. biochem. 2 7 . 1-10. nelson, 1. r . & wakcham. s . g . 1989: a phytol-substituted chlorophyll c from emihana liirrleyr (prkmnesiophvceae) j phycol. 2 5 . 761-766 niebauer. h . j . & alexander. v . 1989. current perspectives on the role of ice margins and polynyas in high altitude ecosystems. pp. i21-iu in re?. l . & alexander. v . (eds ), proc. 6rh conf. corn. arcrique lnrernar.. 13-15 may 1985. e j brill. leiden. key. f. & loeng. h 1985. t h e influence of ice and hydro graphic conditions on the development of phytoplankton i n the barentssea. pp. 4%63 in gray. j . s . & christiansen. m. e . (eds.): marine brology of polar regrotis a n d effecrs of srrtss on marine orgariisms. j . wilcy & sons. ltd. re?. f . . skjoldal. h . r . & slagstad. d . 1987: primary pro duction in relation to climatic changes in thc barcnts sea pp. 19-46 in h . locng ( e d . ) : the effecr of oceanographic condirions on disrrrburrori a n d popularion dynamics of corn rnercial fish srocks i r i rhe barenrs sea. proc. 3rd soviet norwegian synposium. murmansk. 2f1-28 ma! 1986. inst mar. res.. bergen. richards. f a & thompson. t . g . 1952: the estimation and characterization of planktonic populations by pigment analysis. 11. a spcctrophotometric mcihod for the estimation of plankton pigments. 1. m a r . res. 1 1 . 1 5 6 1 7 2 . roy. s & poulet. s . a . 19yo: laboratory study of the chemical or'. 29. 361-364 composition of aging copcpod fecal matcrial. j . exp. mar. b i o l . ecol. 135. s i x . sakshaug. e . 1989: t h e physiological ecology of polar phyto plankton. pp 61-89 in rey, l. & alexander, v . (eds.): proc. 6rh conf, corn. arcrrque inremar.. 13-15 may 1985. e. j . brill. lcidcn. shuman. f. r . 1978. t h e fate of phytoplankton chlorophyll i n the cuphotic zone of washington coastal waters. p h . d . dissertation. unib. washington. seattle. 243 pp. shuman. f. r & lorenzen. c. j 1975: quantitative degra dation of chlorophyll by a marine herbivore. l i m n o l . ocean ogr 20. 5xib5x6. skjoldal. h r . hasscl. a , . key. f. 8; loeng. h . 19x7: spring ph! toplanktun dcvclopmcnt and zooplankton rcproduction i n the ccntral barcnts sea in the period 1979-1984. p p . 59 8y in h . locng ( c d . ) : the effecr ofoceariographic condirions on disrribiirrori arid popularrori d w i a m i c s of commercial f i s h srocks in [lie barertfs sea. proc. 3rd soviet-norwegian sym posium. murmansk. 2 6 2 8 may 1986. inst. mar. kes.. bcrgen. soohoo. j . b & kicfcr. d a 1982: vertical distribution of phacopigments i i rates of production and kinetics of photooxidaiion. d e e p s e a res. 2 9 . 1553-1563. stauher. j . l. & jeffrey. s w . 19x8: photosynthetic pigments i n fifty-one 5pccies o f marine diatoms. j . phvcol. 24. 158 172. stefansson. u 8: olafsson. j . 1990: anomalous silicatc-nitrate relationships associated with phaeocysrrs poircherrr hloomc. eos 7 1 . 66. strom. s . l . 1988: t h e production of phytoplankton pigment degradation products by ciliate protozoa. €08 6 8 . 1761. struck. a , . cmiel. e . . schneidcr. s & scheer. h . 1990: photo chemical ring-opening i n mesochlonnatcd chlorophylls. pho rocliern phorobiol. 5 1 , 217-222 thingstad. t f . & sakshaug. e. 1990: control of phyto plankton growth in nutrient recycling ecosystems. theory and terminology. m a r . ecol. p r o g . ser. 6 3 . 261-272. thingstad. t. f & martinussen. i . 1991: a r e bacteria active in the cold water ecosystems of the barents sea'? pp. 257-268 in sakshaug. e . . hopkins. c . c. e . & britsland. n. a . (eds.): procecdings of the pro mare symposium on polar marine ecologj. trondhcim. 12-16 may 19yo. pular research i o ( 1 ) . vernet. m . 1989: pigment composition of suspended and sink ing particles in the barents sea. abstract. americun a s s o c i arron of limnology and o c e a n o g r a p h y . fairbanks. alaska. vcrnct. m . & lorenzen. c . j . 1987: t h e relative abundance of phcophorhide a and pheophytin a in temperate marine waters. lrvinol. oceariogr. 3 2 . 352-358. vernet. m . & mitchell, b . g . 1990: r a c e r : phaeopiginent photooxidation during the spring bloom in the gerlacbe strait. artrarcric journal of the united srares x x v . 162-164. wassmann. p.. vernet. m . . mitchell, b . g . & key, f. 1990: mass scdimcntation of phaeocysris poucherii in the barents sea m a r . ecol. p r o g . ser. 6 6 . i x s i y s . warsmann. p . . martinez. r . & vernet. m. 1991: respiration and biochemical composition of scdimcnting organic matter during summer in the barents sea. cont. s h e l f r e s . in press. welschmeyer. n . a . . copping. a . e . . vernet. m. & lorenzen, c . j . 1984. die1 fluctuation in zooplankton grazing rate as determined from the downward vertical flux of phcopigments. mar. biol. 8 3 . 2 6 s 2 7 0 . wclschmeyer. n. a . & lorenzen. c . j . 1985: chlorophyll hudgcts: zooplankton grazing and phytoplankton growth in a temperate fjord and the central pacific gyres. limnol. oceanogr. 30. 1-21 phytoplankton dynamics in the barents sea 145 wright, s. w. & jeffrey, s. w. 1987: fucoxanthin pigment markers of marine phytoplankton analyzed by hplc and hptlc. mar. ecol. prog. ser. 38. 259-266. ziegler, r . , blaheta, a,, guha, n. & schonegge. b . 1988: enzymatic formation of pheophorbide and pyropheophor bide during chlorophyll degradation in a mutant of chlurena fusca shihira et kraus. j . plant physiul. 132, 327-332. patterns of fungal–algal symbiont association in usnea aurantiaco-atra reveal the succession of lichen–moss communities in fildes peninsula, antarctica research article patterns of fungal–algal symbiont association in usnea aurantiaco-atra reveal the succession of lichen–moss communities in fildes peninsula, antarctica shunan cao a, fang pengb, hongyuan zhengc, feng wangc, chuanpeng liud & qiming zhou d akey laboratory for polar science, state ocean administration, polar research institute of china, shanghai, china; bchina center for type culture collection, college of life sciences, wuhan university, wuhan, china; ccollege of environmental science and engineering, tongji university, shanghai, china; dschool of life science and technology, harbin institute of technology, harbin, china abstract usnea aurantiaco-atra is the most widespread flora in fildes peninsula. there are two growth types of u. aurantiaco-atra: the erect form on rocks and the prostrate form associated with mosses. phylogenetic analysis showed that individuals of the two growth forms share genotypes. moreover, haploid disequilibrium testing indicated no significant genetic difference for the two growth forms when fungal and algal internal transcribed spacer rdna were treated as two alleles of one lichen individual. the two growth forms of u. aurantiaco-atra appear to reflect different stages of lichen–moss community succession. a mode is proposed for demonstrating the occurrence of this succession. keywords haplotype; its rdna; linkage disequilibrium; mycobiont; populations; reproduction abbreviations its: internal transcribed spacer; pcr: polymerase chain reaction lichens are pioneer organisms in harsh environments and may dominate the terrestrial vegetation. this is especially true in antarctica, where lichens are the major contributors to biomass and diversity (domaschke et al. 2012). lichens are composed of fungal and algal symbionts that contribute to the thallus biomass and form the typical morphological characters. a relatively stable relationship exists between the fungal and algal partners over time. lichens are formed when a fungal spore germinates and the hyphae encounter the correct algal partner. the hyphae grow and cover the algal cells, eventually resulting in formation of typical lichen structures and completing the lichenization process. this process is observed in lichens with sexual reproduction, such as those with apothecia. lichens can also reproduce by vegetative growth and this is common in lichens with soredia, isidia or thallus fragments. sexual reproduction is an opportunity for a new algal partner to be introduced into the original fungal partner. a horizontal transmission of photobiont can then occur (nelsen & gargas 2008; dal grande et al. 2012). in vegetative reproduction, both fungal and algal partners are transmitted vertically from the parental thallus to the new individual and the offspring genotype is unchanged from that of the lichen parent. linkage disequilibrium, a measure of the nonrandom association of alleles at different loci, is useful for studying the population genetic diversity differences in lichens or fungi that disperse via sexual and asexual reproduction (walser et al. 2004; de fine licht et al. 2006; molina-montenegro et al. 2013). selected gene markers often include its rdna, β-tublin, ef-1α, group i intron in small subunit rdna (cassie & piercey-normore 2008; o’brien et al. 2009). higher genetic diversity is typically observed in populations with sexual reproduction (molina-montenegro et al. 2013). for the co-dispersion of mutualistic organisms, werth and scheidegger (2012) suggested that linkage disequilibrium could provide compelling evidence. significant linkage disequilibrium has been observed between fungal and algal loci indicated mutual lichen thalli propagated by clonality, which indicated that the fungal and algal partners in mutual lichen thalli were vertically transmitted. the fildes peninsula is located at the northern tip of antarctica. it has a mean yearly temperature <0°c, sunshine duration < 600 h, and yearly rainfall/snow < 600 mm (yang et al. 2013). it is an ideal natural area to study flora succession resulting from glacial retreat, ice melt and rising sea levels. conditions around this island present a transition from a glacial to a pedogenic geosystem. only one vascular plant – deschampsia antarctica desv. – has been observed on the island but at least 120 lichen species have been reported (http://www.aari.aq/kgi/vegetation/lst_ lichens.html). the marshy grassland area here is a unique feature of the antarctic terrestrial continent and the plant community is primarily composed of lichens, especially usnea arurantiaco-atra (jacq.) bory, and mosses. contact qiming zhou genbank@vip.sina.com school of life science and technology, harbin institute of technology, 2 yikuang street, nangang distinct, harbin150080, china supplemental data for this article can be accessed here. polar research, 2017 vol. 36, 1374123 https://doi.org/10.1080/17518369.2017.1374123 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0002-3264-851x http://orcid.org/0000-0002-2892-6329 http://www.aari.aq/kgi/vegetation/lst_lichens.html http://www.aari.aq/kgi/vegetation/lst_lichens.html https://doi.org/10.1080/17518369.2017.1374123 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1374123&domain=pdf usnea aurantiaco-atra (formerly u. fasciata torr. or neuropogon aurantiaco-ater [jacq.] i.m. lamb in older literature) is the most conspicuous lichen in fildes peninsula. there are two common growth types of this lichen. the erect type grows on rocks and often harbours apothecia. the prostrate type is attached to moss tufts and lacks apothecia. usnea antarctica du rietz is another widespread species in this region; it grows erect and seems to reproduce via the vegetative structures soredia. recent studies, using molecular data, demonstrated that u. antarctica should be included in u. aurantiaco-atra (seymour et al. 2007). hence, u. antarctica is treated as a erect growth type of u. aurantiaco-atra in this study. the coexistence of different growth forms in the same location make u. aurantiaco-atra a good candidate for exploring transformation and evolution of the growth forms. in the current study, u. aurantiaco-atra with different reproduction and growth forms were collected around fildes peninsula and the its rdna of both fungal and algal partners were sequenced. the relationship between the erect and prostrate types of u. aurantiaco-atra was studied using haplotype and linkage disequilibrium analysis based on its rdna data. the its rdna of u. aurantiaco-atra fungal and algal symbionts were set as alleles and the linkage disequilibrium of these alleles was investigated. we assumed that if linkage disequilibrium (between fungal its and algal its regions) was not observed within the prostrate forms with strictly vegetative reproduction nor within the erect sexual reproduction populations, there should be an evolutionary succession where the erect u. aurantiaco-atra was replaced by the prostrate form coinciding with the appearance of moss. based on these analyses, a possible lichen–moss communities succession is detailed. material and methods a total of 132 u. aurantiaco-atra individuals were collected from 12 sites around fildes peninsula, antarctica (fig. 1; supplementary table s1). the total dna was exacted using a modified cetyl trimethylammonium bromide method (cao et al. 2015). the primer pairs used are listed in supplementary table s2. the sequences retrieved from genbank are listed in supplementary table s3. a 50 μl pcr reaction system was used which consisted of 5 μl amplification buffer (containing 25 mmol l−1 of mgcl2), 1.25 units of taq dna polymerase (takara biotechnology co. ltd.), 4 μl 2.5 mmol l−1 of each dntp, 2 μl10 μmol l−1 of each primer, 6 μl of diluted template dna and 33 μl h2o. the pcr amplification conditions were as follows: initial denaturation at 95°c for 5 min, followed by 30 cycles of 94°c for 40 s, 55°c for 40 s, and 72°c for 2–4 min. these cycles were followed by a final extension at 72°c for 10 min. an abi3730xl sequencer was used and double-stranded pcr products were sequenced. the seqman program within lasergene version 7.1 software package (dnastar inc.) was used to check and assemble the double-directional sequence figure 1. distribution of usnea aurantiaco-atra symbionts (fungal and algal) genotypes and sampling sites. (a) map of the fildes peninsula. twelve sampling sites are marked with roman numerals from i to xii. the fungal its rdna haplotypes are represented by capital letters, a – p. the algal its rdna haplotypes are represented by arabic numerals, 1 – 12. most erect individuals had apothecia whereas prostrate individuals lacked them. (b) typical u. aurantiaco-atra with apothecia, erectly growing on rocks. (c) typical prostrate u. aurantiaco-atra, growing with moss. (d) fungal–algal genotypes distribution displayed as a column diagram. 2 s. cao et al. data. the small subunit and large subunit regions of rdna were trimmed off. preliminary alignment of the fungal its rdna sequences together with those retrieved from genbank was performed using clustalw algorithm within mega 5 and then adjusted manually (tamura et al. 2011). the same operation was performed for the algal its rdna sequences. the fungal and algal its haplotype networks were calculated using tcs 2.1 (clement et al. 2000), respectively (supplementary fig. s1). the linkage disequilibrium of its rdna between fungal and algal symbionts was calculated using genalex 6.502 (peakall & smouse 2012). nucleotide diversity, genetic diversity and molecular diversity indexes were calculated using arlequin 3.5 (excoffier & lischer 2010). results and discussion the fungal and algal its sequences for all 132 samples were submitted to genbank (supplementary table s1). fungal its rdna sequences clustered into one branch as u. aurantiaco-atra supported with 99 bootstraps (supplementary fig. s1a). meanwhile, all the algal its rdna assigned as trebouxia jamesii (supplementary fig. s1d). both the phylogenetic analyses and haplotype network results revealed 16 haplotypes for the fungal symbiont (marked from “a” to “p,” supplementary fig. s1b). a total of 14 haplotypes were identified from the erect growth types, 10 of which were unique (haplotypes b, d, e, g, j, k, l, m, o and p). six haplotypes were identified from the prostrate growth types, two of which were unique (haplotypes i and n). four fungal its haplotypes were shared by both growth types (haplotypes a, c, f and h) (fig. 1a, d). both the phylogenetic analyses and haplotype network results showed 12 haplotypes for the algal symbiont (marked from “1” to “12,” supplementary fig. s1d). all the 12 algal its haplotypes have been identified from the erect growth types, and three haplotypes were identified from the prostrate growth types (haplotypes 1, 3 and 8) (fig. 1a, d). the most widespread u. aurantiaco-atra genotype was “a1” (“a” is the fungal haplotype and “1” is the algal haplotype). thirty-eight of 132 individuals possessed genotype a1, and 24 of them appeared within the erect populations. a total of 14 individuals were prostrate forms without apothecia (fig. 1a, d), supplementary table s1). usnea aurantiaco-atra individuals with two distinct growth types not only share the same algal partner t. jamesii but also share the same genotypes. for example, individuals iii-02 and iii-08 share the same genotype “a8”, but the former has an erect growth type and the latter has a prostrate growth type (fig. 1a, d), supplementary table s1). arlequin results showed that there was only minor molecular diversity difference between two u. aurantiaco-atra growth forms. for the fungal its rdna (498 bp after alignment), prostrate u. aurantiaco-atra showed relatively higher nucleotide diversity (0.0021 ± 0.0016), genetic diversity (0.5200 ± 0.1143) and molecular diversity indexes (1.022) than those with erect growth type (0.00160 ± 0.0013; 0.4918 ± 0.0590; 0.787, respectively). for the algal its rdna (663 bp after alignment), u. aurantiaco-atra with prostrate growth had relatively lower nucleotide diversity (0.0023 ± 0.0016), genetic diversity (0.3415 ± 0.1104) and molecular diversity indexes (1.523) than individuals with erect growth (0.0023 ± 0.0016; 0.7585 ± 0.0238; 1.548, respectively). for the fungal—algal its rdna (1161 bp after alignment), u. aurantiaco-atra with prostrate growth had a relatively higher nucleotide diversity (0.0022 ± 0.0014), molecular diversity index (2.545), and relatively lower genetic diversity (0.7077 ± 0.0946) than individuals with erect growth (0.0020 ± 0.0012; 0.8803 ± 0.019; 2.335, respectively). the its rdna from fungal and algal partners were treated as one allele to estimate the combination pattern of the symbionts, and to test the difference of haploid disequilibrium between the erect and prostrate types (table 1). there was no significant difference between the erect type (p = 0.649) and prostrate type (p = 0.704). this result indicated the fungal and algal symbionts within the two u. aurantiaco-atra growth types were randomly matched. haploid disequilibrium was not observed in the prostrate individuals lacking apothecia. discussion although there are two distinct growth types of u. aurantiaco-atra, the lichen-forming fungi and its algal partner were identified as one species, respectively, based on its rdna analyses (supplementary fig. s1). molecular diversity indicated only minor differences between these two growth types (with and without apothecia). the its rdna of u. aurantiaco-atra fungal and algal symbionts were set as alleles and the linkage disequilibrium of these alleles was investigated. we supposed that the fungal and algal partners were transmitted vertically (clonally) if significant linkage table 1. haploid disequilibrium test of usnea aurantiaco-atra symbionts (haploid disequilibrium, 999 randomizations). growth type no. samples vea vob vo/vec no. permutations p (vr ≥ vo)d erect 106 0.437 0.447 1.024 999 0.649 (ns) prostrate 26 0.471 0.448 0.951 999 0.704 (ns) athe expected variance. bthe observed variance. cthe index of linkage disequilibrium. dvr calculated for each random sample as the variance of the randomized data set and the probability of observing a vr value as extreme as that measured for the original data (vo). polar research 3 disequilibrium of the alleles was observed. when u. aurantiaco-atra propagated by sexual reproduction, the linkage disequilibrium could not be observed within offspring because of the recombination of fungi and algae during lichenization. there are two distinct growth types in u. aurantiaco-atra, and reproduction within these two growth forms was obviously different. individuals with erect growth may propagate with apothecia (sexual reproductive structure) or soredia, but individuals with prostrate growth lack such structures and probably undergo dispersal via thallus fragments. the linkage disequilibrium values of the assumed allele (its rdna of fungal and algal partner) of these two u. aurantiaco-atra populations were similar. these data suggested an explanation of the evolutionary succession that may have occurred in the fildes peninsula. since the fungal partner of the sampled lichen thalli was confirmed to be one identical species (u. aurantiaco-atra), the offspring thalli of u. aurantiacoatra with sexual reproduction produced by ascospore-lichenization and the offspring thalli of u. aurantiaco-atra with vegetative reproduction produced clonally (fungal and algal partners co-dispersal) could be distinguished from their population structures and the linkage disequilibrium values. linkage disequilibrium (between fungal its and algal its regions) was not observed within the populations with sexual reproduction. in contrast, an obvious linkage disequilibrium was observed within the prostrate forms that reproduce vegetatively. the value of linkage disequilibrium within the prostrate population was similar to that of the erect populations. this suggests that these two populations had a similar “sexual ancestor.” combining the observations from the local micro-environment, we propose an evolutionary succession model of lichen–moss communities (fig. 2). initially only u. aurantiaco-atra can grow on gravel (fig. 2a, d); after soil appears following the growth of u. aurantiaco-atra, moss colonizes the area (fig. 2b, d); the environmental factors are changed by the development of mosses and humidity increases within the moss vegetation. as a direct result, u. aurantiaco-atra detaches from the gravel because the root portion of lichen thalli may decay in high humidity micro-environment (fig. 2c, d). the prostrate growth form of u. aurantiaco-atra degrades as a result of moss competition (kappen & redon 1987). unattached u. aurantiaco-atra must grow in direct contact with mosses or else winds would blow the thalli into the sea. as a result, a long and curly plant morphology evolves (fig. 2d). the prostrate thalli never bear fruiting bodies and they are less productive than erect form individuals (kappen 1985). this suggests that the prostrate individuals are actually “the degraded” or “root rotten-thalli unattached” status of those with erect form, which explains why a similar linkage disequilibrium value was observed within both populations. we consider the its rdna of the fungus and its algal partner as a pair of alleles. the prostrate individuals of u. aurantiaco-atra were expected to exhibit a strict linkage for its rdna of the two partners if they originated from sterile ones by vegetative reproduction such as lichen fragment dispersal. such a linkage would not be observed in erect u. aurantiaco-atra because most individuals were considered to have derived from the joint union of a parent fungal spore and its photobiont; a random match occurred when these parent fungal spore met a compatible algal partner. we could also conclude that the reproduction of the lichen populations experiences the evolution of horizontal transmission if no linkage occurs between the fungal and algal partners. molina-montenegro et al. (molina-montenegro et al. 2013) reported the nurse effect of u. antarctica figure 2. photographs of (a) tangled prostrate usnea aurantiaco-atra, (b) moss beneath u. aurantiaco-atra (tangled prostrate removed), and (c) gravel beneath moss (moss removed); and (d) diagram illustrating the succession of lichen–moss communities. 4 s. cao et al. in which cushions (formed by prostrate usnea) ameliorate the extreme conditions of antarctic islands by increasing temperature, soil moisture and nutrient availability, decreasing radiation, and water loss from evaporation. we noted moss cushions under the tangled prostrate u. aurantiaco-atra in most circumstances, and the lowest substrates were gravels (fig. 2a–c). hence, a succession model of lichen– moss communities with different stages is presented (fig. 2d). erect u. aurantiaco-atra is ancestral and derived from lichenized fungal spores and compatible algal partners. the prostrate type is a degraded type of the erect type, and the diffusion method for prostrate individuals without apothecia is not vertical transmission, as revealed by the linkage disequilibrium analysis. a loss of vitality for prostrate type individuals would be expected because they are degraded without roots attached to gravel and they have to adapt to a different micro-environment and bryophyte competition. the growth rate and the potential net photosynthesis of prostrate u. aurantiaco-atra are much lower than in the erect form (elisabeth tschermakwoess 1988; li et al. 2014). conclusion the haploid disequilibrium test results indicated no linkage disequilibrium in the prostrate population of u. aurantiaco-atra and there was no significant difference between the erect and the prostrate growth types. since linkage disequilibrium can be viewed as an indicator of reproduction mode in lichens, this result indicates that the prostrate individuals were not clonally derived. usnea aurantiaco-atra without apothecia should be derived from sexual reproduction, similar to those with apothecia. a succession model of antarctica lichen–moss is proposed to explain the differentiation of the two u. aurantiaco-atra phenotypes. the micro-environment has an important influence on lichens that have phenotypic plasticity. this succession model is helpful for understanding lichen evolution in the harsh antarctic environment. acknowledgements we are indebted to the anonymous reviewers for valuable suggestions that improved this manuscript. we are grateful to the chinese arctic and antarctic administration for helping in carrying out the project at the great wall station. our research was facilitated by the polar samples resource-sharing platform (http://birds.chinare.org.cn/) and the polar science data-sharing platform (http://www. chinare.org.cn) maintained by the polar research institute of china and the chinese national arctic & antarctic data center. disclosure statement no potential conflict of interest was reported by the authors. funding this research was supported by the international cooperation programme of the chinese national arctic research expedition (ic201514), chinese polar environment comprehensive investigation and assessment programmes (no. chinare2016-02-01) and national infrastructure of natural resources for science and technology program of china (no. nimr-2017-8); state oceanic administration [ic201514]; state oceanic administration [2012gw03003]. orcid shunan cao http://orcid.org/0000-0002-3264-851x qiming zhou http://orcid.org/0000-0002-2892-6329 references cao s.n., zhang f., liu c.p., hao z., tian y., zhu l. & zhou q. 2015. distribution patterns of haplotypes for symbionts from umbilicaria esculenta and u. muehlenbergii reflect the importance of reproductive strategy in shaping population genetic structure. bmc microbiology 15, article no. 212, doi: 10.1186/s12866-015-0527-0 cassie d.m. & piercey-normore m.d. 2008. dispersal in a sterile lichen-forming fungus, thamnolia subuliformis (ascomycotina: icmadophilaceae). botany 86, 751–762. clement m., posada d. & crandall k.a. 2000. tcs: a computer program to estimate gene genealogies. molecular ecology 9, 1657–1659. dal grande f., widmer i., wagner h.h. & scheidegger c. 2012. vertical and horizontal photobiont transmission within populations of a lichen symbiosis. molecular ecology 21, 3159–3172. de fine licht h.h., boomsma j.j. & aanen d.k. 2006. presumptive horizontal symbiont transmission in the fungus-growing termite macrotermes natalensis. molecular ecology 15, 3131–3138. domaschke s., fernández-mendoza f., garcía m.a., martín m.p. & printzen c. 2012. low genetic diversity in antarctic populations of the lichen-forming ascomycete cetraria aculeata and its photobiont. polar research 31, article no. 17353, doi: 10.3402/polar.v31i0.17353 excoffier l. & lischer h.e. 2010. arlequin suite ver 3.5: a new series of programs to perform population genetics analyses under linux and windows. molecular ecology resources 10, 564–567. kappen l. 1985. water relations and net photosynthesis of usnea. a comparison between usnea fasciata (maritime antarctic) and usnea sulphurea (continental antarctic). in d.h. brown (ed.): lichen physiology and cell biology. pp. 41–56. new york: plenum press. kappen l. & redon j. 1987. photosynthesis and water relations of three maritime antarctic lichen species. flora: morphologie, geobotanik, oekophysiologie 179, 215–229. li y., kromer b., schukraft g., bubenzer o., huang m.r., wang z.m., bian l.g. & li c.s. 2014. growth rate of usnea aurantiacoatra (jacq.) bory on fildes peninsula, antarctica and its climatic background. plos one 9, article no. e100735, doi: 10.1371/journal.pone.0100735 polar research 5 http://birds.chinare.org.cn/ http://www.chinare.org.cn http://www.chinare.org.cn https://doi.org/10.1186/s12866-015-0527-0 https://doi.org/10.3402/polar.v31i0.17353 https://doi.org/10.1371/journal.pone.0100735 molina-montenegro m.a., ricote-martínez n., muñozramírez c., gómez-gonzález s., torres-díaz c., salgado-luarte c., gianoli e. & woods k. 2013. positive interactions between the lichen usnea antarctica (parmeliaceae) and the native flora in maritime antarctica. journal of vegetation science 24, 463–472. nelsen m.p. & gargas a. 2008. dissociation and horizontal transmission of codispersing lichen symbionts in the genus lepraria (lecanorales: stereocaulaceae). new phytologist 177, 264–275. o’brien h.e., miadlikowska j. & lutzoni f. 2009. assessing reproductive isolation in highly diverse communities of the lichen-forming fungal genus peltigera. evolution 63, 2076–2086. peakall r. & smouse p.e. 2012. genalex 6.5: genetic analysis in excel. population genetic software for teaching and research—an update. bioinformatics 28, 2537– 2539. seymour f., crittenden p., wirtz n., øvstedal d., dyer p. & lumbsch h. 2007. phylogenetic and morphological analysis of antarctic lichen-forming usnea species in the group neuropogon. antarctic science 19, 71–82. tamura k., peterson d., peterson n., stecher g., nei m. & kumar s. 2011. mega 5: molecularevolutionary genetics analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods. molecular biology and evolution 28, 2731–2739. tschermak-woess e. 1988. the algal partner. in m. galun (ed.): crc handbook of lichenology. vol. 2. pp. 39–94. boca raton: crc press. walser j.-c., gugerli f., holderegger r., kuonen d. & scheidegger c. 2004. recombination and clonal propagation in different populations of the lichen lobaria pulmonaria. heredity 93, 322–329. werth s. & scheidegger c. 2012. congruent genetic structure in the lichen-forming fungus lobaria pulmonaria and its green-algal photobiont. molecular plant–microbe interactions 25, 220–230. yang q.h., zhang b.z., li m. & meng s. 2013. analysis of weather and sea ice at the antarctic great wall station in 2012. chinese journal of polar research 25, 268–277. 6 s. cao et al. abstract material and methods results and discussion discussion conclusion acknowledgements disclosure statement funding references sea foam as an object of sea-surface film studies nikolai v. druzhkov, pavel r. makarevich and serge1 i. bardan druzhkov, n. v., makarevich, p. r . & bardan, s. i. 1997: sea foam as an object of sea-surface film studies. polar re.search 16(2), 117-121. sea foam and sea-surface films are pelagic habitats of common origin. this suggests a possible similarity between their microplanktonic assemblages and an a priori possibility to use foam samples in qualitative sea-surface film studies. the composition and abundance of microheterotrophs (nanoflagellates <5 pm and bacteria) in the dalnezelenetskaya inlet, kola peninsula, barents sea, in august 1987, was nearly identical in the foam and sea-surface film samples. in contrast, the enrichment of foam with autotrophs (nanoand microphytoplankton) exceeded by an order of magnitude that of sea-surface films, whereas their taxonomic compositions were virtually identical in both habitats. elevated growth rates of phytoplankton in sea foam appear to be an ecological mechanism responsible for the enrichment. n . v. druzhkov, p . r. makarevich and s . i . bardan, munnansk marine biological institute, department of plankton and microbiology, 184 631 murmansk region, dalnie zelentsy, russia. introduction at present, the methods for studying the biology of sea-surface films are subject to ardent criticism. different sampling devices (garret 1965; harvey 1966; daumas et al. 1976; van vleet & williams 1980; carlson 1982; ignatiades 1987) do not adequately sample sea-surface films due to variable entrapment of the underlying layer of the water column. sea-surface films may be >200 pm thick and thus introduce considerable and unpredictable distortions of the information on the structure of microhyponeuston commu nities (williams et al. 1986). the situation is aggravated by the absence of adequate methods for obtaining realistic in-situ estimates of the thickness of sea-surface films. as a result available estimates of the numbers and biomass of microorganisms inhabiting sea-surface films may differ from real levels by several orders of magnitude. since all known modifications of the samplers do not solve the above methodological problem, we have changed the very object of investigation to the study of sea foam. some detailed investigations exist which deal with the biological and chemical characteristics of sea foam (khailov 1971; baire et al. 1974; velimirov 1980), but the origin of this habitat has not previously been considered to be related to the sea-surface films. the formation of sea-surface films at the air-water interface is due to the processes that lower the level of free energy and which are accompanied by the adsorption of organic matter (home 1969). at sites where sea surface films are mechanically compressed, tightly packed slicks emerge, appearing like mirror smooth patches and bands on a rough sea surface (williams 1967). typical sites of slick formation in open areas are convergence zones (shienok 1986). mechanical condensation of sea-surface films through slicks to stable foam is mediated by mixing processes accompanied by intense frothing with entrapped air bubbles. this may occur, for example, by wave breaking, langmuir circulation, mixing of fresh and salt water, or as a result of forced compression against shores (williams 1967; velimirov 1982; shienok 1986). the formation of foam is therefore structurally related to sea-surface films, and a priori one can expect certain biological similarities in both habitats, especially since the life-span of sea foam seldom exceeds a few hours. the most conspicuous exception to this rule may be the foam ridges that arise from phaeocystis blooms along the north sea shores (lancelot et al. 1987). we here compare sea-surface films and sea foam by the surface/volume factor, which allows estimates of the influence of linear dimensions on the biological properties of these habitats. given that sea-surface films and slicks vary from 1 to 1 0 p m in thickness (williams et al. 1986), the surfacelvolume factor ranges from 2000 to 20,000. for sea foam, considering that the thickness of bubble walls averages 5 pm (popov et al. 1979), the corresponding value is about 4000. therefore, the surfaceholume factors of 118 n. v. druzhkov et al. both habitats are quite comparable, suggesting that they are also comparable with respect to microplankton assemblages that are “imprisoned” by their formation. sea-surface films and sea foam are of common origin. as a rule, sea foam is a short-lived and not a specific habitat of marine ecosystems. adequate sampling of stable foam does not give rise to any methodical difficulties compared with the sam pling of sea-surface films. foam samples are therefore believed to be useful in studying the composition and some biological properties of sea-surface film microbiota. in order to verify this suggestion, we have undertaken research to compare microplanktonic assemblages that occu py three different habitats: sea-surface films, stable sea foam, and the underlying layer of the coastal pelagic zone. material and methods sampling was carried out in the coastal zone of the southern barents sea (dalnezelenetskaya inlet: 69”07’n; 36’05‘e) on 31 august 1987, when an intense formation of sea foam (a rather rare ecological event in the study area) was observed after a three-day period of rough weather. during the sampling period, relatively calm weather combined with sufficiently large patches of foam (up to 30-40cm in diameter) floating on the sea surface favoured accurate collection of materials. samples of foam, accumulated in the embay ment by the onflowing tide, were collected by means of a thin plastic sheet without touching the sea surface. they were then allowed to settle to fluid state in 1-liter glass vials for 20-30 min. settling was conducted in a refrigerator at the ambient temperature of about 7°c. sea-surface film samples were collected by a screen sampler as used by carlson (1982). the top locm layer was sampled with a i-liter sampling bottle (culturing flask, 3 cm width), oriented parallel to the sea surface. the enumeration of autotrophic nanoplankton was carried out under the epifluorescent micro scope mld-1 in 25-50ml live samples which were concentrated on 0.65 pm polycarbonate membrane filters (dubna, moscow region) at 280 x magnification (druzhkov & makarevich 1987). one to two-liter microphytoplankton samples, concentrated to 3wom1, were screened over 1 pm polycarbonate membrane filters with a reverse flow device (sukhanova 1983) and then preserved with buffered formalin (final concen tration 1%). microalgal cells were counted and identified in 0.5 ml counting chambers (5 replicas) after repeated reduction of sample volumes to 2-3 ml by sedimentation (fedorov 1979; tsyban 1982). live samples of heterotrophic nanoplankton were enumerated in the 0.5 ml counting chambers (5 replicas) in phase contrast (biolar) at 350x magnification. only moving cells of 1-5 pm size were counted because counting of the larger and motile flagellates was beyond the capacity of the method. because accurate visual separation of large motile bacteria from the smallest motile protists was extremely difficult within the limits of the method used (see cynar et al. 1985), we considered it reasonable to combine all the counted cells into one group of nanoheterotrophs. one-milliliter bacterioplankton samples were concentrated on 0.1 1 m black polycarbonate membrane filters and preserved with 96% ethanol. the filters were stained with fluorescamin accord ing to the method of poglazova & mitskevich (1984), and bacterial cells were counted under the epifluorescence microscope mld1 at 1250 x magnification. enrichment indices (e) were calculated as ratios between the densities of microplankton in sea-surface films and sea foam, and those in the top pelagic zone. all data presented below are means of three replicas. the corrected concentra tions of plankton organisms for sea-surface film (tables 1 and 2) were calculated from the following assumptions: (1) the thickness of a sampled layer is about 200 pm (carlson 1982); (2) the thickness of the proper sea-surface film is 5 pm; (3) the water that is in direct contact with the highly structured sea-surface film layer is biologically similar with the water from locm depth due to continuous microconvection at the air-water interface (fedorov & ginzburg 1992). results and discussion the numbers of microplankton presented in table 1 indicated intense concentrating in sea-surface films and sea foam, a phenomenon well known for sea foam as an object of sea-sugace film studies 119 table 1. abundance ( lo3 cells ml-') of various microplanktonic groups in sea foam, sea-surface film and top pelagic zone (10 cm layer). habitat nanophytomicrophytoheterotrophic plankton plankton nanoplankton bacterioplankton sea foam 283.3 7.1 6.7 78.9 sea-surface film: measured concentrations 1.2 0.01 0.3 2.1 corrected concentrations 40.4 0.4 7.9 62.8 top pelagic zone 0.2 0.003 0.1 0.5 table 2 . calculated enrichment indices (e) for sea foam and sea-surface film. nanophytoplankton microphytonanophytobacterio habitat 1-8 pm 9-16 pm 17--24 pm total plankton plankton plankton sea foam 1240 1694 3750 1334 2554 107 142 sea-surface film: measured concentrations 5 7 5 6 4 4 4 corrected concentrations 179 254 200 197 137 128 113 table 3. percentage of three dominant taxa of diatoms (% of the total microphytoplankton number), three size groups of the nanophytoplankton (w of the total nanophytoplankton number), and four morphological groups of the bacterioplankton (% of the total bacteria number) in sea foam, sea-surface film and the top pelagic zone (standard error of per cent given in parentheses). taxa sea foam sea-surface film top pelagic zone microphytoplankton: licmophora sp. leptocylindrus danicus navicula spp. nanophytoplankton: 1-8 pm 9-16 pm 17-24 pm bacilli cocci coccobacilli ellipsoid forms bacterioplankton: 56.7 (1.51) 1.1 (0.32) 22.3 (1.27) 89.7 (1.17) 9.0 (1.10) 1.3 (0.43) 26.9 (5.71) 50.0 (6.65) 22.4 (5.50) 1.7 (1.71) 77.7 (2.78) 3.2 (1.17) 15.4 (2.41) 90.6 (1.86) 8.9 (1.81) 0.4 (0.40) 28.0 (5.94) 52.1 (6.57) 18.7 (5.68) 1.3 (1.50) 53.6 (5.09) 4.3 (2.07) 23.2 (4.31) 93.2 (3.80) 6.8 (3.80) 0.0 18.2 (5.00) 56.8 (6.61) 23.9 (5.08) 1.1 (1.38) highly structured contact microlayers (bezdek & carlucci 1972; hardy 1982; williams et al. 1986; cullen et al. 1989). most surprising was the fact that the abundance of autotrophs exceeded that of heterotrophs by an order of magnitude. appar ently, the enrichment of sea foam with micro plankton exceeded that of sea-surface films by several orders of magnitude (table 2). however, there is an evident underestimation of the biomass in sea-surface films due to a sampling procedure that cannot exclude the entrapment of water from the layer, underlying sea-surface films. using the correction method described above, the corrected concentrations of plankton organ isms in sea-surface film (table 1) and enrichment indices calculated for these concentrations (table 2) differ considerably from the corrected values. for heterotrophs, the corrected densities and enrichment indices for sea-surface film were similar to the values recorded in foam. in contrast, the numbers and indices calculated for both sea surface film microalgal groups were lower than their abundance in foam by an order of magni tude. for diatoms, the above lack of similarity 120 n. v. druzhkov et al. cannot be easily explained by differences in microalgal taxonomic composition. indeed, the relative abundances of dominant taxa were not significantly different in any of the microphyto plankton assemblages (table 3). small benthic diatoms accounted for 80.1 to 96.3% of micro algal biomass in all three habitats. the similarity of the microheterotrophic com munities from sea-surface film and sea foam would suggest a common origin of two structures, whereas the much stronger enrichment of the sea foam with nanoand microphytoplankton contra dicts such a suggestion. the elevated concentra tions of autotrophs in the foam samples may be explained by the active migration from sea surface films, differential adherence, or, more probably, by a considerable increase of growth rates, resulting in a rapid rise in micro algal biomass (hardy 1982; catalan 1986). in general, there is an evident similarity in microbiotas from sea-surface film and sea foam. the similar percentage compositions of microphytoplankton, nanophytoplankton and bacterioplankton (table 3) in these two habitats suggest a tightly coupled genesis of the assemblages. moreover, our results also demonstrate a similarity of the microbiotas from these two habitats with that of the top layer of the pelagic zone. significant differences were recorded only for the largest fractions of micro algae, i.e. diatoms and flagellates of 17-24 pm size (table 3). these differences are quite under standable since the walls of foam cells are too thin to provide a habitat appropriate to the organisms larger than 5-10 pm. there is no complete identity between the assemblages inhabiting the sea foam and sea surface film. sea foam as living space for unicellular organisms is characterised by extre mely specific chemical and physical properties (velimirov 1980, 1982; bgi-locher et al. 1988; craig et al. 1989). in turn, the characteristics of sea-surface films and sea foam are strongly dependent on the metabolic activity and composi tion of microplankton (especially on those of microalgae) in the subsurface bulk water, demon strating clear seasonal variability (craig et al. 1989; hardy & apts 1989; saliot et al. 1991; gladyshev et al. 1993). it seems therefore true that the problem of the biological and chemical similarity between the two habitats is multi dimensional and has no simple solution. the above results have demonstrated that there is some support for the formulation of a new quantitative approach to sea-surface film and sea foam research since the composition of micro heterotrophs and their enrichment indices were rather similar in the two habitats. a few earlier reports indicated the relative independence of the abundance of bacterioneuston and their enrich ments from physical and chemical variables (maki & remsen 1988). therefore, further joint studies of microplankton in the two habitats should be of great interest. acknowledgements. we are deeply grateful to 0. n. baitaz and the late v. a. baitaz for preparing the data on bacterioplankton. references bake, r. e., groupil, d. w., perlmutter, s. & king, k. 1974: dominant chemical composition of sea-surface films, natural slicks, and foams. j . rech. atmos. 8, 571400. biirlocher, f., gordon, j. & ireland, r. j. 1988: organic composition of seafoam and its digestion by corophium volutator (pallas). j . exp. mar. biol. ecot. 115, 179-186. bezdek, h. f. & carlucci, a. f. 1972: surface concentration of marine bacteria. limnol. oceanogr. 17, 566-569. carlson, d. j. 1982 a field evaluation of plate and screen microlayer sampling techniques. mar. chem. 1 i , 189-208. catalan, j. 1986 approximacion a la composicion y organiza tion del newton. oekol. aqunt. 8, 25-38. craig, d., ireland, r. f. & bbrlocher, f. 1989: seasonal variation in the organic composition of seafoam. j . exp. mar. biol. ecol. 130, 71-80. cullen, j. j., macintyre, h. l. & carlson, d. j. 1989: distributions and photosynthesis of phototrophs in sea surface films. mar. ecol. prog. ser. 55, 271-278. cynar, f. j., estep, k. w. & sieburth, j . mcn. 1985: the detection and characterization of bacteria-sized protist in +protist-free+ filtrates and their potential impact on experimental marine ecology. microb. ecol. 11, 281-288. daumas, r. a., laborde, p. l., marty, j. c. & saliot, a. 1976: influence of sampling method on the chemical composition of water surface films. limnol. oceanogr. 21, 319-326. druzhkov, n. v. & makarevich, p. r. 1987: nanophytoplank ton. pp. 10-11 in makarevich, p. r. & druzlikov, n. v. (eds.): metodicheskie rekomendatsii p o analizu kolichest vennykh i funktsionalnykh kharakteristik morskikh biotseno zov severnykh morei. tsast i . fitoplankton. zooplankton. organ itseskoe veshestvo (methodical recommendations on the analysis of quantitative and functional characteristics of the arctic marine ecosystems. part i. phytoplankton. zooplankton. particulate organic matter). kolsky nauchny tsentr rossiyskoi akademii nauk (kola science centre of russian academy of sciences), apatity (in russian). fedorov, k. n. & ginzburg, a. i. 1992 the near-sui$ace layer of the ocean. vsp, utrecht. 259 pp. fedorov, v. d. 1979: 0 nietodakh izucheniya fitoplanktona i ego aktivnosti (on the methods of study ofphytoplankton and their activity). izdatelstvo moskovskogo universiteta (mos cow univ. press), moskva. i68 pp. (in russian). sea foam as an object of sea-surjiace film studies 121 garret, w. d. 1965: collection of slick-forming materials from the sea surface. limnol. oceanogr. 10, 602-605. gladyshev, m. j . , kalachova, g. s. & sushchik, n. 1993: free fatty acids of surface film of water in the sydinsky bay of the krasnoyarsk reservoir. int. rev. gesamt. hydrobiol. 78, 575-587. hardy, j. t. 1982: the sea surface microlayer: biology, chemistry and anthropogenic enrichment. progr. oceanogr. 11, 307-328. hardy, j. t. & apts, c. w. 1989: photosynthetic carbon reduction: high rates in the sea-surface microlayer. mar. biol. 101, 411417. harvey, g. w. 1966: microlayer collection from the sea surface: a new method and initial results. limnol. oceanogr. 11, 608-613. home, r. a . 1969: marine chemistry. the structure of water and the chemistr)i of the hydrosphere. wiley-interscience, div. of john wiley & sons, new york. 398 pp. ignatiades, l. a. 1987: a simple apparatus for sampling sea surface microlayers. mar. ecol. prog. ser. 39, 207-208. khailov, k. m. 1971: ekologitsesky metabolizm v more (ecological metabolism in the sea). naukova dumka, kiev. 252 pp. (in russian). lancelot, c., billen, g., soumia, a,, weisse, t., colijn, f., veldhuis, m. j. w., davies, a. & wassman, p. 1987: phaeocystis blooms and nutrient enrichment in the con tinental coastal zones of the north sea. ambio 16, 3 8 4 6 . maki, j. s . & remsen, c. c. 1988: examination of a freshwater surface microlayer for die1 changes in the bacterioneuston. hydrobiologia 182, 25-34. poglazova, m. n. & mitskevich, i. n. 1984: primenenie fluoreskamina dlya opredeleniya kolichestva mikroorganiz mov v morskoi vode epijluorestsentnym metodom. mikrobio logiya (application of fluorescamin for assessment of bacteria abundance in the sea water with the use of the epifluorescence microscopy). mikrobiologiya 53, 850-858 (in russian). popov, n. i., fedorov, k. n. & orlov, v. m. 1979: morskuya vodu (sea water) nauka, moscow. 327 pp. (in russian). saliot, a,, marty, j. c., scribe, p., siore, m. a., viets, t. c.. de leeuw, j. w., schenck, p. a. & boon, j. j. 1991: charac terization of particulate organic matter in mediterranean sea surface films and underlying water by flash pyrolysis and gas chromatographic analyses. org. geochem. 17, 329-340. shienok, v. a. 1986: 1 kharaktere vetrovogo vozdeistviya na ekosistemn melkogo vodoyoma (impact of the wind activity on the ecosystem of shallow basins). pp. 217-218 in: 5 syezd vsesoyuznogo gidrobiologicheskogo obshestva, to liyatti, 15-19 sentyabrya 1986 goda. tsast i (proceedings of the fifth all-union conference of the all-union hydro biological society, toliyatti, 15-19 september 1986. part i). kuibyshevskoe knizhnoe izdatelstvo, kuibyshev (in russian). sukhanova, i. n. 1983: kontsentrirovanie fito planktona v probe (concentrating the phytoplankton sam ples). pp. 97-108 in vinogradov, e. m. (ed.): sovremennye metody kolichestvennoi otsenki raspredeleniya morskogo planktona (the modem methods of the quantitative assess ment of marine plankton distribution). nauka, moscow (in russian). tsyhan, a. v . (ed.). 1982. rukovodstvo p o metodam biolo gicheskogo analiza morskoi vody i donnykh otlozheniy (manual of biological analyses of seawater and bottom sediments). gidrorneteoizdat, leningrad. 191 pp. (in rus sian). van vleet, e. s. & williams, p. m. 1980: sampling sea surface films: a laboratory evaluation of techniques and collecting materials. limnol. oceanogr. 25, 764-170. velimirov, b. 1980 formation and potential trophic signifi cance of marine foam near kelp beds in the benguela upwelling system. mar. biol. 58, 31 1-318. velimirov, b. 1982: sugar and lipid components in sea foam near kelp beds. mar. ecol. 3 , 97-107. williams, p. m. 1967: sea surface chemistry: organic carbon, nitrogen and phosphorus in surface films and subsurface water. deep-sea res. 14, 781-800. williams, p. m., carlucci, a. f., henrichs, s . m., van vleet, e. s., horrigan, s. g., reid, f. m. h. & robertson, k. j . 1986: chemical and microbiological studies of sea-surface films in the southern gulf of california and off the west coast of baja california. mar. chem. 19, 17-98. heavy metals and macroelements in the tundra of southern spitsbergen: the effect of little auk azze azze (l.) colonies barbara godzik godzik b.: heavy metals and macroelements in the tundra of southern spitsbergen: thc effect of little auk a66e alle ( l . ) colonies. polar research 9 ( 2 ) , 121-131 samples of two species of widely distributed mosses (sunioniu uncinuru and hylocomium .splendrt7,\) wcrc eollccted in the ariekammen-fugleberget catchment aica (hornsund. spitsbergen) within and out5idc little auk alle ulle (l.) colonies. the concentrations of cd. ph, ni. zn, cu. mn. fe. n . p , and s i n t h e moss samplcs were found to be 1.5-2 times higher within than outsidc the colonies. significant diffcrcnco were found for cd, pb, zn, cu, and fe, but not for ni, m n , n . p. and s . saniorliu urlcir~ura accumulate5 up to 8 fg gg' d . w t cd, 14-pb, %ni, 47-211, 9-cu, 90-mn, and 1920 kg g ' d . w t fc, while hylocornrurn splendens accumulates up t o 4 k g g ' d . wt cd, 12-pb. 3-ni. 31-zn, 5-cu. 60-mn, and 840pggg' d w t fe. the colonies of seabirds contributc greatly t o the supply of elements in the tundra ccosy\tcms of southern spitsbergen. the effect seems, however, to be limited to rather small areas. barbara godzik, w . szafer institute of botany, polish academy of sciences, lubicz 46, 31-512 krukdw, poland. introduction the arctic tundra consists mainly of mosses, lichens, and, to a lesser extent, vascular plants. the vegetation cover is compact in a several kilometre-wide strip along the coast, while the vegetation further inland is more sparse (billings 1973). in arctic regions, the activity of seabirds is one of the main factors that determines the diversity of vegetation and the degree of vegetation cover. in the fiornsund region little auk alle alle occurs in large numbers while kittiwake rissa tridactyla, black guillemot cepphus grille, brunnich's guille mot uria lomuia, fulmar fulmarus glacialis, glau cous gull larus hyperboreus, and others are less dominating. large amounts of nutrients are deposited through the faeces of birds. con stituents of the faeces are dissolved by precipi tation and thawing waters, transported through tundra systems by temporary streams (krzyszow ska 1983), and partly washed out to sea. the remainder is utilized by the vegetation, which is always more abundant close to sites inhabited by birds than elsewhere (eurola & hakala 1977). on the coastal cliffs close to the polish polar station at hornsund there are large colonies of little auks. the little auks feed mainly on cope pods (calanus sp.) during the summer (glutz von blotzheim & bauer 1982; evans 1981) and on other small marine crustaceans and fish during the autumn (lydersen et al. 1085, 1988). marine animals in the hornsund region contain fairly high concentrations of heavy metals (prota sowicki 1988). according to godzik (unpubl. data), various species of marine animals (amphipoda: gummarellus homari; decapoda: eualus gaimardi, hyas araneus; echinodermata: heliometra glacialis; pisces: myxocephalus scor pius, liparis ziparis) from the hornsund area contain about 1.14-6.43 pg g ~ ' d. wt cd, 2.2 43.5 pb, 2.5-13.5 ni, 49.7-185.3 z n , 4.ws.o cu, 3.5-22.1 mn, and 56.8-514.0 pg g-' d. wt fe. it can be assumed that little auks feeding on these species deposit considerable amounts of the same elements in the tundra ecosystems through their faeces. because mosses absorb heavy metal ions, they are often used in the assessment of heavy metal pollution of the environment (riihling & tyler 1978, 1971; pakarinen & tolonen 1976; grod zinska 1978). by using the common moss species sanionia uncinata and hylocomium splendens, this project has aimed at assessing the effect of colonies of little auk on the concentrations of heavy metals, sulphur, nitrogen, and phos phorus in the tundra ecosystem of southern spits bergen. 122 barbara godzik fig. 1 . location of hornsund ( a ) and sites of moss s m p l i n g in the hornsund area ( b ) . i = ariekammen: 2 = fugleherget: 3 = gnalhcrgrt; 4 = rasstupet. heavy metals and macroelernents in the tundra of southern spitsbergen 123 0 3 0 0 600m 0 fig. 2. sites of moss sampling in ariekammen-fugleherget watershed. a = polish polar station: b = water pool: c = fuglebckken river: d = hans glacier moraine. broken lines indicate houndarics of the watershed area. slopes of the ariekammen (511 m a.s.1.) and fug leberget (569111 a.s.1.) mountains and the flat terrain in the southern part of t h e catchment (fig. 2 ) . in the western part of the catchment area. on the slopes of ariekammen, there is a colony of about 50 thousand pairs of little auks. a mosaic pattern of rock rubble divides the colony into rather autonomic subcolonies. t h e density of study area the studies were carried out on a fragment of tundra vegetation in the fuglebekken river catch ment area close to the polish polar station at hornsund in the southwestern part of spitsbergen (76"59'n, 15'33' e) (fig. 1a). t h e catchment area comprises the southern and southeastern 124 barbara godzik breeding pairs is usually one pair per 1.5-2.0 m' (stepniewicz i9xo). in the eastern part of the catchment area (slopes of fugleberget) little auks occur less frequently. accompanied by small col onies of kittiwakes. the flat part of the study area is a feeding ground for the pink-footed goose atiser hrachl.rl7,-ticiiir.s. the vegetation of the ariekammen-fugle berget catchment area is variable. the western part (southern slope of ariekamman) is "ferti lized" by birds and supports abundant orni thocoprophilous plant communities, a condition lacking in the eastern part (dubiel & olech in press). materials and methods sanioniu iincinoru (hedw.) loeske and hyl coriiirirn sp1eridetz.s (hedw.) b. s. g . are the most widespread moss species occurring in both the "fertilized" and "nonfertilized" parts of the catch ment area. samples of these mosses were col lected in june 1986 within the ariekammen fugleberget catchment area (fig. 2) and at several other sites in the hornsund fiord (fig. 1b; table 1). samples were taken in the western part of the catchment area, along three transects leading from points elevated about 3 0 0 m a.s.1. on the slopes of ariekammen towards the flat coastal terrace about 10 m a.s.1. (19 samples, locations 1-19), in the eastern part of the catchment area at the foot of fugleberget (3 samples, locations 2&22), close t o gnilherget (1 sample, location 23), and on rasstupet (2 samples, locations 24 25). some of the sanionia uncinata samples were collected within bird colonies: little auk colonies on ariekammen (locations 2 4 , % l l , 18), col onies on fugleberget (location 2&21), within geese-feeding ground (location 14), and within a colony of kittiwake on rasstupet (location 25). the remaining samples were collected outside bird colonies or feeding grounds. five samples of hylocomium splendens were collected within little auk colonies, on arie kammen (locations 9-11, 18) and fugleberget (location 20). the remaining samples were col lected either above or below the colonies. moss samples were air-dried and then oven dried at 105°c to constant weight. the samples were slowly digested in a 4 : 1 mixture of spectral tuble i . n u m b e r of samples and localities of mos) collcction in the hornsund region (a = within hird colonies: b = outside bird colonic%) species sanioriio uncinatu hvlocomium spendens locality a ariekammen b 8 samples locations: 2 . 3. 1. 9. 10. 1 i . 11.18 4 samples locations: 9, 10. 11. 18 11 simples 7 samplcs locations. i . 5. 6. 7 , 8 . 12. 13. is. 16. 17. 19 locations: i . 5. 8. 12, 16. 17, 19 ~~ d 2 samples 1 sample locations: 20. 21 location: 20 fugleberget b 1 sample 1 sample b 1 sample location: 22 a location: 24 rasstupet location: 25 a b gnilodden 1 sample location: 23 heavy metals and macroelements in the tundra of southern spitsbergen 125 3 8 i -j pure hitric and perchloric acids o n a hot plate for 3 days until all organic matter was oxidized. t h e solution was then evaporated t o 1 ml and diluted with distilled water to 50 ml. blanks were run f o r each series of samples. t h e paper bags in which the plants had been stored were treated in the same way as the moss samples. t h e con centrations of c d , pb, ni, z n , cu, mn, and fe 2 3.84 10.9 1.9 31.1 5.0 35.4 428.3 2860 1729 2.09 3 6.33 12.9 2.8 42.2 6.8 37.6 575.4 2980 1895 2.37 4 7.90 12.0 2.6 46.9 8.0 34.7 530.6 3200 1856 2.34 were determined with a n atomic absorption spectrophotometer (varian-techtron model a 1000). t h e measurements were repeated on a hitachi 180-80 spectrophotometer. sulphur was determiend by a nephelometric method, nitrogen by kjeldahl method, and phosphorus by a vanado-molybdate method (nowosielski 1968). the concentrations were determined collec fuglebcrgct table 2. heavy metal, phosphorus, sulphur (yg g-' d.wt), and nitrogen (%) concentrations in sunionia uncinatu collected in the hornsund area (localities within bird colonies have been given in frames). locality n o cd ph ni zn cu mn fe p s n 20 1.87 9.5 5.4 17.6 10.0 72.7 1362.3 71 21 1.08 9.7 6.0 18.2 8.3 106.1 1919.7 1303 1.37 1 1.58 6.3 1.8 18.3 3.8 25.3 407.1 1880 1206 1 . 1 6 ~ 8 2.41 11.1 2.6 22.4 3.7 38.3 289.6 1700 1264 0.94 9 1.97 13.7 8.1 37.4 6.8 90.2 839.7 2390 1143 1.66 10 2.12 13.7 2.7 22.4 4 . 2 42.7 866.9 i670 1023 1.24 i i 4.48 12.2 1.9 33.9 5.4 29.1 486.3 2880 18x6 2.07 12 4.47 8 . 5 1.8 37.6 5.2 38.5 174.7 3240 1649 2.20 13 1.32 4.3 1.7 21.7 4.3 36.6 220.5 2630 1522 1.69 y u .w 8% a $ i 1 14 1.13 10.4 5.3 21.6 8.4 71.4 1354.5 2800 1361 1.59 1 15 0.81 11.7 4.6 13.6 3.7 41.3 1058.4 2650 1058 1.03 ~ 16 1.82 8.8 2.2 14.2 2.6 21.5 184.3 1370 1127 1.12 17 1.64 9.0 2.7 12.9 5.0 36.5 794.7 1670 1303 1.24 18 1.66 10.8 5.6 22.0 8.7 88.0 331.4 1970 1071 0.89 19 1.56 6.3 1.7 17.3 3.8 17.0 301.4 1960 1311 1.14 w 3 3 i :: 5 i ~ 22 i s 6 10.6 2.6 13 1 2 8 32.8 425.5 1460 1273 i 19 gnilodden 23 1.25 7.4 2.6 15.1 2.9 10.7 253.0 1630 1208 0.68 1 24 3.15 12.7 2.1 16.2 2.6 14.5 212.2 2320 1744 1.37 i rasstupct 25 1.62 7.9 2.1 12.3 1.2 12.6 59.7 1570 1120 0.91 126 barbarn godzik tuhk 3. mean concenlrations of heavy mctals. phosphorus. sulphur (big g i d.wt) and nitrogen (7%) in sunionia uncinata collected within thc httle auk colon) on the dope d ariekammcn ( 1 ) . outside the little auk colony on the slope of ariekammen (11). in amall bird colonies a t the foot of fugleherget and rasatupet (111). outside small bird colonies on fugleberget. gniloddcn and ra5stupet (i\'). ~ locallt> cd pb x i zn c u m n fc p s n 1 ( 2 . 3 , 4. 9. 10. 1 1 ) i! ( i . 5 . 6 . 7.s. 12. 1.;. is) i l l ill! ' i . 2 4 ) i \' ( 2 2 . 2 3 . 2 5 ) \ sd \ sd \ sd \ 51) 17.3 3.7 1 . 2 0 2 3 3 6.2 2 . 4 3 1 0 0 . 8 5 10.58 4.7 i 4 7 1.76 8.6 2.4 1 . 7 2 0 . 2 y tively for the green and brown parts of the mosses. only three samples of sanionia ~rncirzata were subjected to separate analysis of the green and brown parts. differences in heavy metal con centrations were assessed by a kruskall-wallis and student t-test. the heavy metal index (s,) was calculated according t o a procedure suggested by grodzinska (1978) from the formula where x,, is the content of i-heavy metal in j location; xi mean content of i-heavy metal in all locations: in this case j equals 7 ( c d . ph. ni. zn. mn, f e ) . results the chemical composition of the samples of sanionia itticinata collected across the arie kammen slopes varies considerably (table 2 ) . cadmium and manganese show the widest ranges. and lead, copper, sulphur and phosphorus showed the narrowest ranges. t h e variation is particularly high in the con centrations of heavy metals and macroelements found along transects i and 11; variation along transect 111 is much smaller. along transect i. the concentration of cadmium increases sixfold in locations approaching the centre of a colony; that of lead. zinc and nitrogen increases twofold; and the remaining elements increase about 1.5 times. the highest concentrations were found at locations 3. 4 and 9 where the nests of birds were 33.7 6.4 5 1 . 1 57y.8 2564 1515 1.41 0 . 4 1 1.63 36.2s 202.41 569.7 413.7 0.568 i y 3 4.0 55.1 436.x 2 l i h 1310 1.34 9 4 1 1.16 11.29 4112.70 591.') 2 2 4 . 8 0 . 4 2 5 is4 7 3 hh.7 1111.7 7545 l4lx 1.55 2 2y 3 25 3s.lll 717.75 3(a1 5 2 2 1 . 4 0.237 13.7 2 3 18.7 346.1 1.553 1203 0.03 1 . 3 0 . y 5 12.25 ix3.0(1 86.2 79.3 0 2 5 5 most densely arranged. a m o n g locations situated within the colonies, the lowest concentrations of elements were found in moss from location 18 which has few nests of little auks (table 2). when samples of the s a m e species of moss were collected o n the ariekammen slopes outside the colonies of little auks (localities 1. 5 . 6. 7 . 8, 12. 13, 15). the average concentrations of cadmium, lead and zinc were less t h a n half those found within the colonies, concentrations of copper and manganese were about one-third. and of nickel and iron about one-fourth as much (table 3). samples of the moss s. rcncinatu collected at locations with few birds (localities 20, 21. 24) contained less t h a n half the amount of the con centrations of cadmium and zinc found within colonies o n the ariekammen slopes and similar concentrations of the remaining elements (table 3). lower concentrations of heavy metals and macroelements were found in the samples of s. wicinara collected about 100-300 metres below the small groupings of nests (table 3). the differences in concentrations of cd, pb. zn. cu. and fe in the mosses collected within and outside colonies were statistically significant ( p < 0.05). the total index (s,) of heavy metal con centrations in the mosses allows the separation of the site locations into low content locations (index values ranging from -0.45 to 0.0) and high con tent locations (index values ranging from 0.0 t o 0.63). the first group comprises the locations outside the bird colonies; the latter comprises those within the colonies (fig. 3). the moss hvlocorniittii splendens is a weaker heavy metal accumulator than saniorziu icncinata. heavy metals and macroelements in the tundra of southern spitsbergen 127 300 600m fig. 3. index of heavy metal contents of the moss sunionin unciriala collected on the slope of m f . ariekarnrncn. solid circlc ( 0 ) = localities within the alle alle colony (index value: 0.0-0.64) and in the feeding ground of anser bracliyrhynchus (locality 14, index value: 0.44). opcn circle (0) = localitics outside the aue nle colony (index value: 0 . 6 0 . 0 ) . other explanations as in fig. 2 . h. splendens accumulated only about half the amount of cd, ni, zn and mn, and about two third the amount of the remaining elements as did s . uncinuta. similar to s. uncinata. samples of h . splendens collected within colonies contained higher heavy metal concentrations than those from outside bird-inhabited sites (table 4). the concentrations of heavy metals in the younger, green parts of s. uncinata mosses were always lower than those in the older brown parts (fig. 4). the greatest differences occurred in ni and mn concentrations. the brown parts con tained 3 to 12 times more ni and mn than the green parts. the concentration of cadmium was 1.5 to 2 times higher, lead 2-3 times, zinc 3-5 times, and copper 3-7 times more than in the green parts (fig. 4). the differences were stat istically significant (p < 0.05). phosphorus and 128 barbara godrik table 4. heavy nmal\. phosphorus. sulphur (lcg g ' d.wtl and nirrogcn 1 % ) conccnlrations of thc moss h ? . k u m t i t o i t .~p/ivtdi~tt.v collectcd in the hornwnd iircil (localitics within bird colonic., hmc. $ken in friimcs). l ~ k ' i l l i l ~ $1) cd pb x i zn cu xln f c p $ 3 ~ ~~ i 1i.yh 3 . 8 11.7 13.2 2.1) 17.7 173.1 isw) 827 1.15 5 i l . x . 1 3.5 1.11 13.1 2 . 5 21.3 2lu.y im) 9-34 1.1)l h 1 . l w l 12.1.1 1.h 1 1 . 1 2.7 16.1 .ixx.7 1720 my 1.37 13.11 iyz.(i i 3 w l hy)o 0.y4 ill.? 3.9 ih.? 473.1 1 3 y j hy2 ll.wl 163') 1.92 .2 i2 ii.'j5 5 . 2 11.5 lll.4 2.3 111.4 259.2 1340 605 i).81 9.y 2 . 2 11.5 245.1 1631) iiuy 1.05 < i -l ' u i.(lh 8.6 l . y 12.: 3.7 i 111 1.w 11.3 2.3 ! i 1 4.23 7.11 1.7 3 1 . 5 4.4 28.4 316.2 2wi ! & i il l ih i.jii 6.1 i1.y i 1 . 1 1 ) h.x 2.2 1ll.il 2,s 32.4 562.1 i2wl lln7 0.67 57.6 x-lo.2 13x0 -1 i--; is l..w ? . 5 2 . x 1s.s 4.1 i u ii.w 5.y 1.7 11.5 4.h 13.4 142.1 1421) ' 2 5 ) i l h y hird wlon\ < 1.y' s . 6 2 . 2 l d . 4 4.11 2x.x3 4 5 5 6 17ml iinix i . i u ( s l ) 1,544 i . y 2 il.4y 0.43 0.3ll 211.29 2 x i i . x 4 737.9 4 3 . 5 1i.sx cwtsitlc \ i . i h c 6.2 1.3 i i ..: 2.7 17.5 282.2 i524 001 11.96 bird idon! sd ii.ls4 2.s3 11.62 1.3s 0 . x 7 7.55 i4h.68 172. i 150.7 k?56 -.. -. . i----..__ . .----- !-- f u $ l c l l ~ l ~ c . l ' 31 1 . 7 s 5.1) 2. 12.6 3 . 4 11.7 m4.h 2(mi 1173 i ..- sulphur were accumulated most efficiently in the brown parts. while nitrogen in the green parts (fig. 4). discussion the group nesting of seabirds i n the far north regions is a major factor in influencing t h e varia bility and abundance of plant associations. in the sites fertilized by bird facces. specitic orni thwoprophilous associations have developcd (eurola & hakala 1977: dubiel &i olech in press). the presence of a great colon): (comprising more than so thousand pairs) of little iluks on the slope of the ariekammen mountains has caused vegetation to thrive much better than elsewhere in thc catchment area. the little auks remain in their breeding colonies from mid-june to mid-august before later migrat ing south. in this period. egg-laying. incubation. and feeding of the young take place. adult and young birds consume about 280 metric tonnes of marine food during this period. about a third of this amount is voided as faeces deposited mainly within the colonies (klekowski & opalinski 1983). previous studies have shown that the con centrations of nitrogen (as nitrates) and phos phorus in surface waters were high within the colonies but decreased with increasing distance from the colonies (krzyszowska 1985). similarly. the concentrations of n, p and s in mosses collected within little auk colonies at hornsund were higher than those found in mosses growing on sites not inhabited by birds. this indicates the effect bird colonies have on the levels of macroelements in tundra vegetation of the region. such elevations of macroelement con centrations were also found in higher plants of spitsbergen by staaland et al. (1983). the range of colony-related effect is small. the concentrations of heavy metals in mosses collected less than 100 m from bird nests are simi heavy metals and macroelements in the tundra of southern spitsbergen 129 1 i zn mn b/ 200 p m !003 ow 4 2 1 ' i 1 ' c p il 1 2 3 1 2 3 1 2 3 1 2 3 locolily 0 =green pork h9 = brown p o r t s fig. 4. h e a v y metal, phosphorus, sulphur (pg g ' d . wt) and nitrogen (%) concentrations in green and brown parts of the mosc sanionia uricinata (localities i . 2, and 3 , southern slope of mt. ariekammenll. 130 barbara godzik table 5. tlrav! mctal. phmphorus. sulphur ( ~ i g ' d . wt) and nitrogen ( % ) concentrations i n the green ( a ) and brown (h) parts of the nicw suniormc uncinaru llocalities i . 2. and 3 o n the southern slope of m t . ariekammcn). locallt v i 2 3 _ _ element d sd h sd a sd b sd a sd b sd cd pb ni zn c u hln fe p 5 n i . 7 1 8.6 1.5 13.9 2.1 12.1) 239.2 1340 i035 1.19 0 104 1 .oo 0.10 2.31 0 29 2.42 15.70 3.21 10.2 5.8 34. i 5.4 95.3 1661.3 1650 1 i43 0.97 0.226 1.90 1.87 7.50 0.59 2.5 2.69 13.2 0.75 5 2 6.01 21.1 261.68 451.1 1690 1204 1.12 0.223 1.21 0.57 3.20 2.30 62.83 0.96 lar to (except for cadmium) the levels found else where in hornsund. according t o data by grodzinska & godzik (1991, this volume). mean concentrations of heavy metals in sanionia unci natci from many locations in hornsund area are ( p g g i ) : c d . 0.59; p b , 7.07; ni, 4.25; c u , 6.01; and z n . 21.13. hylocomium splendens accumu lates similar quantities of these elements. since concentrations of cadmium. lead and zinc in sanionia uncinata and hylocomiuni splendens col lected within bird colonies a r e considerably higher than the levels found o n many locations elsewhere in southern spitsbergen, the faeces of sea birds is an important source of heavy metals in sites inhabited by birds. higher concentrations of heavy metals found in older (brown) parts of mosses compared with younger (green) parts agree well with findings by other authors (lotschert e t al. 1975; grodzinska 1978). it may thus be concluded that colonies of sea birds play an important role in introducing heavy metals and macroelements t o the tundra eco systems of southern spitsbergen. t h e range of this effect is limited to the closest surroundings of colonies of nests. acknowledgernenrs this work was supported by the polish academy of scicnccs. programme cpbp 03.03. references billings, w. d. 1973: arctic and alpine vegetations: similarities. differences and susceptibility to disturbance. bioscience 2 3 . 697-703. 2.75 22.6 23.2 68.8 28.1 298.4 5184.7 2290 1059 0.97 0.193 0.92 5.55 3.50 20.48 499.81 1.70 1.34 7.2 2.9 12.5 5.0 43.3 474.7 1810 949 1.18 0.166 0.29 0.42 1.67 0.29 3.70 41.68 2.43 15.3 10.3 34.6 13.8 116.3 3218.7 2333 834 0.91 0.221 2.45 1.32 3.76 i .42 8.14 375.43 dubiel. e. & olech, m. (in press): ornithocoprophilous plant communities on the southern slopes of ariekammen (hornsund region. spitsbergen). i n opalinski. k . w. & kle kowski. r. z . (eds.): spitsbergen '84: landscape. life, world and man in high arctic. institute of ecology publishing. ossolineum, wroclaw, 1992. eurola. s . & hakala, w . k. 1977: the bird cliff vegetation of svalbard. aquilo. ser b o t . 15. 1-18. evans, p. g . h. 1981: ecology and behavior of the little auk alle alle in west greenland. ibis 123, 1-18. glutz von blotzheim. u . n. & bauer. k. 1982. handbuch der vogel mitteleuropus. akademische verlagsgesellschaft. wiesbaden. 8/11, 1209-1228. grodzinska. k. 1978: mosses as bioindicators of heavy metals pollution in polish national parks. water. air. soil pollut. 9 , 83-97. grodzinska. k . & godzik, b . 1991: heavy metals and sulphur in mosses from southern spitsbergen. polar research 9(2). 13s140. klekowski. r. z . & opalinski. k . w. 1984: mattcr and energy row i n spitsbergen tundra. wiad. ekol. 30. 133-166. krzyszowska. a. j . 1983: wlasnosci chemiczne wbd pow ierzchniowych i gciek6.w na wybrzeiu zatoki isbjmnhamna (fiord hornsund. spitsbergen). pp. 102-103 in xi1 zjazd hydrobiolog6w polskich w luhlinie. keferaty plenarne i st reszczenia komuni ka t6w. lu blin, krzyszowska. a . j . 1985: chernistryof the fugleberget drainage basin. pol. polar res. 6 ( 3 ) , 341-347. lbrxhert. w . . wandtner, r . & hiller. h . 1975: schwer metallanreicherung bei bodenmossen in imissionsgebiten. ber. deursch. bar. ges. 88. 419431. lydersen, ch.. gjertz. i . & wplawski, j . m . 1985: aspects of vertebrate feeding in the marine ecosystem in hornsund, svahdrd. norsk polarinstitutt rapportserie 2 1 . 57 pp. lydersen, ch., gjetz. i . & wcslawski. j . m . 1988: stomach contents of autumn-feeding marine vertebrates from hornsund. svalbard. polar record 25. 107-1 14. nowosielski. 0. 1968: merod? o:nac:ania potrreb nawoieniu. pwril. warszawa. 688 pp. pakarinen. p. & tolonen. k. 1976: regional survey of heavy metals in peat mosses (sphagnum). anibio 5 , 3 n o . protasowicki, m. 1988: wstcpne badania zawartosci hg. cd, pb. cu i zn w golcu (salvelinus alpinus l . ) i innych organiz mach z rejonu hornsundu. pp. 375-379 in: j a h n . a . . heavy metals and macroelements in the tundra of southern spitsbergen 131 pereyma. j . & szczepankiewicz-szmvrka (eds.): xv sym pozjum polarne. stan obecny i wybrane problemy polskicb badan polarnych. wydawnictwa uniwersytetu wroclawski ego, wroclaw. riihling. a . & tyler, g. 1968: a n ecological approach t o the deposition of heavy metals over scandinavia. bor. noriser 121. 321-342. ruhling. a . & tyler. g. 1971: regional differences in the deposition of heavy metals over scandinavia. j. appl. eco[. 8, 497-507. staaland, h., brattback, j . , ekern. k. & kildemo, k. 1983: chemical composition of reindeer forage plants in svalbard and norway. holnrctic ecobgy 6, 109-122. stcpniewicr, l . 1980: breeding biology of little auk plautus alle in the hornsund region, spitsbergen. acfo om. 28, 1 26. the pelagic distribution of marine birds in a heterogeneous environment george l. hunt, jr. hunt, g. l., jr. 1990: the pelagic distribution of marine birds in a heterogeneous environment. polar research 8 , 43-54. in this paper i review recent, small-scale, process-oriented studies of the pelagic distribution of marine birds. i examine the roles played by a variety of hydrographic features, including steep flow gradients (fronts) and water column stratification, in determining thc abundance or availability of avian prey. the ice edge/marginal ice zone is a frontal area of particular interest in polar regions. in most oceanic systems we have examples of avian use of a feature, hut only poor information on the importance of the feature for supporting the population as a whole. i review recent studies of the spatial and numerical concordance of marine birds and their prey, and find that these studies have yielded mixed results, with corrclations stronger for piscivorous birds, particularly murres foraging on capelin, than for planktivores. review of investigations of multispecies interactions during foraging shows that flock foraging has both bcneficial and negative aspects. interspecific facilitation of foraging occurs in numcrous interactions involving both other species of birds and marine mammals. however, co-occurrence of predators may occur becduse both seek the same prey, and caution must be used in assessing mutualistic interactions between predatory spccies. george l . hunt, jr., department of ecology & evolutionary biology, universiry of california, lroine. ca 92717, u.s.a.; june 1989. recently, hunt & schneider (1987) examined the similarities in distribution and abundance patterns of zooplankton and seabirds at a variety of spatial and temporal scales. in their review, it was appar ent that mapping of seabird distributions at the scale of major portions of the world ocean has given way t o more detailed studies of birds and oceanographic processes at the scale of tens to hundreds of kilometers. in this review, i focus on recent smaller-scale, process-oriented studies, many of which have been published since hunt & schneider (1987) was compiled. the ultimate goal of pelagic studies of marine birds is to understand the processes underlying the observed distribution and abundance of birds at sea. these processes include three related elements: 1) aspects of the physical regime that result in either the passive accumulation of prey or increased production of prey, 2 ) the amount and type of prey present and its availability, and 3 ) interactions with other organisms that enhance a bird’s ability t o locate prey or that result in competition for the prey, once found. in the ideal study of seabirds at sea, we would like to measure simultaneously hydrographic structure and process, as well as the distribution and abundance of both predators and their prey. usually it is not possible to obtain a complete suite of these data. often, therefore, we must infer the processes responsible for the observed patterns. in particu lar, when we lack information on prey abundance and the behavior of foraging individuals, we must assume that variations in prey availability are responsible for the observed variations in seabird abundance. estimating the importance of features within the larger geographic areas that constitute the water types or habitats occupied by seabirds. seabirds are not uniformly distributed (ashmole 1971; shuntov 1974; ainley & boekelheide 1984; schneider et al. 1988). this patchiness is fre quently associated with physical processes that vary in spatial scale from relatively small lang muir cells to fronts associated with continental shelf slopes and major ocean currents (hunt & schneider 1987; brown 1988). when concen trations of foraging birds frequently associate with some feature, we infer that this feature is the location of a major trophic transfer of energy to birds. the question remains whether these foraging areas are the most important sites for trophic transfer, or if the majority of trophic 44 g . l . hunt, j r . transfer occurs through individual birds scattered, seemingly at random, over the ocean. for instance, in a study of birds in the vicinity of the ice edge in the canadian high arctic, mclaren (1982) found that the majority of birds were for aging offshore, even though densities were often higher along the edge of the land-fast ice. we infer that we have identified correctly important trophic pathways and the physical pro cesses responsible for creating the preferred for aging habitats when there is repeatability of results between locations with similar physical features, or between years at the same feature. for example, phalaropes (phaearopus) during their ‘pelagic’ stage have been found to con centrate at frontal areas and upwellings associated with major boundary currents off california (briggs et al. 1984), peru (brown 1980a), the southeastern (haney 1985) and northeastern united states and canada (orr et al. 1982; powers 1983) and the canary current in the east ern tropical atlantic (brown 1979; cadee 1981) (see also brown 1988 for other references). sev eral of these studies were based on multiple visits to an area over a period of two or more years. in this instance we can have considerable confidence that we have identified the most important marine habitat of this avian group. migrant shearwaters (pujjlinus spp.) in the north pacific, like the phalaropes, are associated with shelf waters offshore of coastal upwelling systems (briggs & chu 1986; briggs et al. 1987). at least in california, these birds are not found in the coldest, most recently upwelled water, but farther offshore, possibly associated with con vergences near the shelf edge (briggs & chu 1986). in the bering sea, their greatest numbers are generally in the vicinity of the front between the stratified waters of the middle domain and the well-mixed waters of the inner domain (hunt et al. 1981; schneider 1982; schneider et al. 1986; guzman & myers 1987). within this region of the bering sea, the shearwaters are extremely patchy in distribution and we have no data on the factors controlling patch size or the small-scale distri bution of flocks. hydrographic structures one of the most robust generalizations con cerning the distribution of seabirds on continental shelves is that cross-shelf gradients in seabird distributions are consistently stronger than long shelf gradients. this pattern reflects the under lying physical regimes. recent studies in the bering sea (iverson et al. 1979; schneider &hunt 1982; schneider et al. 1986; schneider et al. 1988), the eastern pacific ocean off california (briggs et al. 1987; briggs et al. 1988), the western atlantic ocean off the southeastern united states (haney & mcgillivary 1985b) and the benguela current off southern africa (schneider & duffy 1985; schneider et al. 1988) provide examples of seabird distributions that change in response to frontal systems parallel to continental shelf bathy metry. in each of these systems, going from near shore waters to offshore waters, one crosses a series of watermasses separated by fronts. the watermasses typically differ in their temperature and salinity characteristics. additionally, hydro graphic structure, driven by a combination of bathymetry and currents, may differ between watermasses. as a result, adjacent water masses frequently have different prey communities and trophic pathways. the southeastern bering sea provides an example of a 500 km wide shelf system that is partitioned into three domains (iverson et al. 1979; coachman 1986). plankton and fish com munities trap a substantial portion of the primary production in a pelagic food web in the outer shelf domain, but in the middle domain much of the carbon settles to the bottom (walsh & mcroy 1986). as a result, seabirds in the middle domain are primarily subsurface foragers and those in the outer domain are surface foragers (schneider & hunt 1982; schneider et al. 1986). currents may also carry different prey com munities into an area. in the northern bering sea, currents of different origin establish three distinct marine habitats (coachman et al. 1975; kinder & schumacher 1981). unlike the southeastern bering shelf, bathymetry is not the major deter minant of watermass boundaries in the region between st. lawrence island and the bering strait. the various watermasses support strikingly different zooplankton communities. these dif ferences are reflected in the foraging and breeding distributions of seabirds in the northern bering sea and the chukchi sea (springer & roseneau 1985; springer et al. 1984,1987; hunt & harrison unpublished). other ocean systems also provide examples of shifts in seabird food webs between water masses. in the barents sea, belopol’skii (1961) showed that arctic cod (boreogadus saida) are of prime pelagic distribution of marine birds 45 ent waters. in an examination of 62 crossings of fronts, densities of birds were not significantly greater at the fronts, on average, than over nearby waters. however, these authors found that those fronts with the steepest flow gradients had elev ated numbers of birds present more frequently than weaker flow gradients. although this result provides an important insight into habitat use by marine birds, it is not clear whether strength or predictability of strong flow gradients is the more important factor. numerous examples exist of predictable, but temporally varying tidally gen erated flow gradients that are important foraging areas for local populations (e.g. brown 1980a, b; braun & gaskin 1982; vermeer et al. 1987; brown & gaskin 1988; cairns & schneider 1990). hydrographic structure may be important in the vertical dimension as well as the horizontal. when water of a lower density rests atop more dense water, the result is increased stability and reduced mixing in the vertical dimension. stable vertical structure has important consequences for planktonic organisms which may concentrate at sharp property gradients (harder 1968; bar roclough et al. 1969). hunt et al. (1990) have shown that least auklets (aerhia pusillu) in the northern bering sea forage in stratified water where echosurveys have revealed concentrations of zooplankton at and above a shallow pycnocline. when the water lacks stratification, even if prey are apparently abundant close t o a colony, the auklets fly to more distant but stratified waters where the prey are at higher densities close to the surface. strong winds are capable of mixing surface waters to considerable depth, thereby deepening the pycnocline and diluting near surface con centrations of plankton. lasker (1979) suggested that such mixing decreased recruitment of first feeding larval northern anchovies (engraulis mor dux) (peterman & bradford 1987), a prey of xantus’ murrelets (synthliborumphus hypoleuca) (hunt & butler 1980). hunt & butler found that in a year of high winds and low anchovy survival, murrelet breeding was considerably delayed (see also lasker 1979). decreased foraging rates of both plunge divers (e.g. salt & willard 1971; dunn 1973) and pursuit divers (e.g. birkhead 1976) as a function of wind speed may reflect increased difficulty in obtaining prey from a greater volume of water as well as greater dif ficulty in flying or spotting prey. the potential importance of vertical as well as horizontal struc importance t o seabirds in the eastern sector which is dominated by arctic water. in the western barents sea, in which warmer north atlantic current water is present, sandlance (amodytes spp.), capelin (mallotus uillosus) and herring (clupeu harengus) are the primary fish taken by birds. similarly, in the north sea, there are dramatic changes in trophic paths to seabirds, depending upon whether the birds are foraging in north atlantic or north sea water (joiris 1983). within the above and other shelf systems, steep flow gradients (fronts) have frequently been identified as important foraging areas for birds (e.g. brown 1980a; schneider 1982; kinder et al. 1983; haney & mcgillivary 1985a, b; veit 1985; schneider, harrison & hunt 1990; schneider, pierotti & threlfall 1990; abrams & lutjeharms 1988). the importance of hydrographic features that enhance prey availability can be particularly great near colonies and foraging distributions around colonies are likely to be patchy (ford et al. 1982), reflecting local oceanographic conditions. competition for food near large colonies is strong (gaston et al. 1983; furness & birkhead 1984; birkhead & furness 1985; hunt et al. 1986) and in some instances prey abundance is depressed (birt et al. 1987). evidence is accumulating that alcids at many colonies concentrate their foraging at a limited number of sites near the colony where currents or tidal flows concentrate or force prey toward the surface often i n a frontal structure (kinder et al. 1983; cairns & schneider 1990; schneider, harrison & hunt 1990; schneider, pierotti & threlfall 1990). in polar regions, ice edge habitats near colonies may be particularly important ‘frontal’ areas in which prey availability is enhanced (brown & nettleship 1981). under standing factors affecting seabird foraging in the vicinity of colonies is particularly important, as a lack of success can affect reproductive success. thus, this area of research is of interest not only t o students of the pelagic biology of marine birds, but also to a growing number of workers on colonies (e.g. wanless et al. 1985; trivelpiece et al. 1986; croxall et al. 1988). many studies of birds at fronts rely on one to a few crossings of the physical structure in question, and the possibility that the reported observation of elevated numbers of birds was a coincidence or a rare event cannot be ignored, schneider et al. (1987) addressed this question by testing whether larger numbers of birds were found at bering sea shelf fronts than over adjac 46 g. l . hunt, jr. ture in defining seabird foraging habitats is only just becoming apparent. the ice edge and marginal ice zone ice cover is a physical feature of major importance to marine birds in high latitude oceans. ice cover determines access to resources, provides a refuge from aquatic predators, and in some situations contributes t o enhanced prey abundance. in the last decade, our understanding of the processes whereby sea ice influences marine bird popu lations has increased greatly, but overall, we still lack sufficient data to assess the magnitude of the contribution of ice-related productivity t o seabird populations. the presence of extensive ice cover can prevent marine birds from acquiring adequate food resources. unlike seals that maintain breathing holes through the ice, marine birds at high lati tudes do not maintain openings, and with the occasional exception of some gulls (laridae) and skuas (stercorariidae), marine birds are rarely present in areas of 100 percent ice cover. when not breeding, marine birds can shift their distri bution to avoid excessive ice cover, and in some cases they aggregate near the edge of the ice while waiting for it to melt (divoky 1979, 1981). in areas of heavy ice cover, polynyas (areas of open water surrounded by ice) may be of critical importance to breeding (and wintering) birds (stonehouse 1967; stirling 1980; brown & nettleship 1981; dunbar 1981). in the northern hemisphere, virtually all large colonies of seabirds i n the north american and european arctic are adjacent to recurring polynyas (brown & nettleship 1981). the importance of open water near colonies is emphasized by the obser vations of nettleship et al. (1984); in a year of unusually heavy ice cover in lancaster sound, canadian high arctic, breeding of thick-billed murres (uria lomuia) was delayed by three weeks. under certain circumstances, sea ice may enhance foraging opportunities for marine birds. in both the arctic and the antarctic, there is a diatom flora associated with sea ice and an under ice or epontic community of zooplankton that forages on exposed ice algae (alexander & chap man 1981; dunbar 1981; bradstreet & cross 1982; smith et al. 1985; garrison et al. 1986). addition ally, in the late winter and early spring, these ice algae provide an innoculum for an algal bloom that occurs in the open water of the marginal ice zone (mcroy & goering 1974; schandelmeier & alexander 1981; smith & nelson 1985, 1986). ‘the melting of ice creates water column stability via a sharp pycnocline below low-salinity melt water (buckley et al. 1979; alexander & niebauer 1981; niebauer 6t alexander 1985; smith & nel son 1986; muller-karger & alexander 1987; smith 1987). additionally, at least in the arctic, upwelling of nutrients at the ice edge occurs due to wind forcing, thereby creating the physical conditions conducive to a strong algal bloom. marine birds in the arctic and the antarctic for age on food webs based on the epontic algae (bradstreet 1980,1988; bradstreet & cross 1982; fraser & ainley 1986). birds also take meso pelagic organisms that come near the surface under the ice, possibly due to reduced light levels (gulliksen 1984; ainley et al. 1986). birds for aging near the ice edge presumably benefit from a concentration of prey organisms at the ice-water interface beneath the ice, a situation in which prey cannot easily escape avian predators (bradstreet 1988). in the antarctic, marine birds forage on a food web based on the algal bloom seaward of the ice edge (fraser & ainley 1986). use of this portion of the marginal ice zone by birds has not been studied in the arctic. however, given the poten tially vast size of the open water portion of the marginal ice zone (up to 250km wide in the antarctic, smith & nelson 1986), one might expect that its contribution to marine birds would be even greater than that of the ice edge and epontic system. this prediction is based on the assumption that algal production is cropped by pelagic zooplankters. if these primary consumers are scarce and pelagic fish largely unavailable (e.g. the middle domain of the bering sea, iver son et al. 1979; cooney & coyle 1982; coyle & cooney 1988), foraging in the open sea portion of the marginal ice zone should not be especially profitable and enhanced numbers of birds would not be expected. considerable evidence points to the importance of the ice edge as a foraging zone for high latitude seabirds. in the canadian high arctic, foraging seabirds concentrate at the ice edge (bradstreet 1979, 1982, 1988; divoky 1981) and thick-billed murres fly up to 100 km from their colonies over open water to forage at the ice edge (bradstreet 1979). in the barents sea, there are similar long pelagic distribution of marine birds 47 within the pack ice. regardless of this lack, it is increasingly clear that the marginal ice zone is a frontal system of great significance to marine birds. distance movements over water to the ice edge (v. bakken pers. comm.). in the antarctic, evi dence is accumulating that the ice edge is an area in which birds concentrate, but the picture appears less clear than it is in the arctic. in the weddell sea, fraser & ainley (1986) observed concentrations of birds and avian biomass near the ice edge, but in the ross sea, ainley & jacobs (1981) found peaks in avian biomass at the ice edge on only one of five transects (their fig. 3a e). because the ross sea ice edge was over the edge of the continental shelf, it is difficult to assess the relative importance of the ice or shelf edge to birds. ainley & jacobs suggest that both factors work together, as did eppley & harrison (1985), who found an elevated number of birds when the ice edge was coincident with the shelf edge near wilkes land. seabird distributions are patchy along the ice edge (bradstreet 1982; bakken & hunt unpublished), and vary in response to fac tors such as wind velocity and the amount of pack ice present seaward of the edge of land-fast ice (bradstreet 1979; mclaren 1982). this patchiness confounds our ability to assess the importance of the ice-edge habitat when survey efforts are limited to one or a few transects across the ice edge zone. assessment of the importance of the ice edge as a foraging zone for seabirds is complicated by the difficulty in delimiting the area of concern from adjacent areas. when there is a sharply defined interface between open water and con tinuous land-fast ice, only the seaward boundary of the ‘ice edge’ zone need be defined. when ice is breaking up and extensive areas of pack ice are involved, there may be a wide zone grading from open water to solid ice cover with no clearly defined edge. the term marginal ice zone has been used to refer to this zone (see smith 1987). however, the zone of stratified water seaward of the ice edge that results from stability imposed by low-density melt-water is also a part of the physi cal regime that results in enhanced productivity in the marginal ice zone. thus, in examining the contribution of sea ice to avian food resources, it is necessary to include the entire region from the seaward edge of this zone of stratified water to water completely covered by ice. to date, there are no published data, of which i am aware, that compare the relative importance to bird popu lations (total bird use) of unstratified waters sea ward of the marginal ice zone, stratified water in the marginal ice zone and the use of open water marine birds in relation to prey resources in recent examinations of the distribution and abundance of birds in relation to prey resources, the working hypothesis has been that predators should aggregate where prey are most abundant. several assumptions are implicit in the for mulation of this hypothesis: (1) there is a close coupling between prey abundance and prey avail ability, (2) the predators are good at detecting prey and evaluating the relative value of prey patches, and (3) predators do not deplete prey patches prior to measurement of prey abundance. the validity of these assumptions has not been tested. correlation between predator and prey abun dance has been sought for both planktivorous and piscivorous species of birds, using a variety of echosounding techniques for measuring prey abundance. for the most part, measures of the abundance of plankton prey explain only a small portion of the variance in seabird abundance, while in contrast, measures of fish abundance have explained large portions of the variance in the abundance of avian piscivores. the strength of correlation in most cases is sensitive to the scale at which measurements are taken. one of the first studies of marine bird distri bution with respect to planktonic prey was obst’s (1985) investigation of the abundance of marine birds in bransfield strait, antarctica, with respect to the abundance of antarctic krill (euphausia superba). obst used a ship’s depth finder as a semi-quantitative measure of krill abundance. h e found that avian density and biomass were higher in waters where krill were present, and, for three species of birds and for all birds combined, the probability that krill was present increased with increasing bird density. however, obst was unable to predict bird density on the basis of relative abundance or depth of krill. in contrast, woodby (1984) in a study of murres (uria s p p . ) in relation to prey in the bering sea, found significant rank correlations between the density of murres and that of euphausiids (thysonoessa s p p . and euphausiapacifica) in one of two years. 48 g. l . hunt, jr. in the second year, no correlation was found between murres and euphausids, and woodby concluded that murres were able t o catch suf ficient prey in the low density aggregations of prey. h e suggested that it might not be ener getically efficient for murres to seek the densest patches of prey. subsequent to these early studies of seabirds and euphausiids, heinemann et al. (1989) and hunt et al. (unpublished) undertook studies of seabirds and krill in antarctica, and hunt et al. (1990) examined the abundance of least auklets with respect to the abundance of copepods (neocalanus s p p . ) in the northern bering sea. using quantitative echosurveys of krill in con junction with counts of birds in bransfield strait, antarctica, heinemann et al. (1989) determined the frequency of miles of survey in which both birds and krill were present (spatial concordance) and correlations of abundance within the spatial units in which both predators and their prey were present (numerical concordance). they found that seabirds of two species, cape petrels (dap zion capensis) and antarctic fulmars (fulmarus glacialoides) , showed spatial concordance with krill but only adelie penguins (pygoscelis adeliae) and cape petrels showed significant correlations with krill abundance. correlations were found over a range of spatial scales from nautical mile intervals to scales of hundreds of nautical miles. generally, correlations (up to 0.99) were stronger at the larger scales, but few were statistically significant. near bird island, south georgia, hunt et al. (unpublished) found positive correlations between antarctic krill and antarctic fur seals (arctocephalus gazella), macaroni penguins (eudyptes chrysolophus) and black-browed albatrosses (diomedia melanophris). however, when the confounding variables of distance and direction from the colony on bird island were factored out, hunt et al. were able to demonstrate an additional influence of krill abundance on predator abundance for fur seals only. in the northern bering sea, least auklets for age on copepods and other small zooplankton found in stratified water 15-55 km offshore of their island colonies (hunt et al. 1990). rank correlations between the abundance of these predators and echosounder estimates of prey abundance were strongest for prey in the portion of the water column above the thermocline. in and prey abundance appeared stronger when scales of measurement were increased from 1-2 nautical miles t o 5-12 nautical miles, although due to sample size considerations, the number of statistically significant correlations dropped at the larger measurement interval. at a measurement interval of 1-2 nautical miles the average of five rz values was 0.25, while for the 5-12 nautical mile intervals it was 0.68. thus, as in the case with the heinemann et al. (1989) study of seabirds and krill in bransfield strait, explained variances were improved at larger measurement intervals. in the northern hemisphere, several investi gators have attempted to determine the strength of correlations between seabirds and forage fish. safina & burger (1988), after an initial failure to detect an influence of forage fish density on common tern (sterna hirundo) density (safina & burger 1985), found in a multiyear study that common tern flock size increased with a number of measures of increasing prey abundance and prey availability (e.g. density, relative abundance in the upper water column). this study is the first to demonstrate statistically significant corre lations between a surface foraging seabird and forage fish, although the correlations are gen erally fairly weak, and the statistical significance of the correlations was driven by the large num bers of tern flocks investigated. the study did not address the problem of the correlation between seabirds and their prey throughout a potential foraging area because their study was focused on foraging flocks and sampling was not independent of bird distribution. in general, we may expect difficulties in associating surface foraging birds with prey density using echosounding surveys of prey because the echosounders are unable to rec ord prey in the top one to ten meters of the water column, depending upon the system used. two investigations of the distribution and abun dance of common murres ( u . aalge) and atlantic puffins (fratercula arctica) with respect to capelin abundance have yielded strong correlations between these birds and their prey (schneider & piatt 1986; piatt 1990; erikstad this volume). in work in the avalon channel between new foundland and the grand banks, schneider & piatt found significant positive correlations between murre and capelin abundance on four out of six transects. scale-dependent correlations between predators and prey occurred on two tran sects for murres and three transects for puffins, four out of five cases, correlations between bird with correlations increasing at larger measure pelagic distribution of marine birds 49 interactions between seabirds and their prey are likely and single measurement distances may fail to reveal significant interactions (schneider & piatt 1986). secondly, in several studies it was apparent that significant correlates between predators and prey were intermittent and that repeated surveys were necessary for detection of correlations (schneider & piatt 1986; safina & burger 1988). additionally, studies focusing on diurnally foraging birds (e.g. alcids) appear to have been more successful in finding positive cor relations than those focusing on southern hemi sphere predators that take krill. many of these krill predators take the majority of their prey at night (croxall et al. 1985, 1988; fraser et al. unpublished) when krill migrate to near-surface waters (mauchline 1980; everson 1983; loeb & shulenberger 1987). most hull-mounted echo sounders are unable to detect krill within 10-20 m of the water’s surface. thus given the difficulties of detecting krill near the surface and counting foraging birds at night, it is possible that surveys of krill predators and krill are unlikely to yield strong correlations at small scales of measurement except under unusual circumstances (e.g. hunt et al. 1985). these problems not withstanding, efforts to correlate avian predators and zooplank ton prey seem t o yield lower correlation values, particularly at small scales, than surveys of fish eating birds and their prey. it is possible that the planktivorous birds are less able to locate the densest patches of prey. alternatively, they may not need to seek the densest patches if back ground densities or the frequency of micro patches of prey at high densities are sufficiently great (woodby 1984; hunt et al. 1990). ment distances. piatt (lyyo), reporting on a longer series of observations, including many in the immediate vicinity of the large common murre and atlantic puffin colonies (about 74,000 pairs of each) in witless bay, newfoundland, found that the abundance of both murres and puffins increased each year in late june when spawning schools of capelin arrived inshore. thereafter, there was a strong temporal correlation between the abundance of capelin and the abundance of these alcids. piatt found that murres (68% of 63 surveys) and puffins (54% of 70 surveys) were significantly correlated with capelin at a measure ment scale of 0.5 km and correlations grew increasingly stronger with increasing measure ment interval on 35% of murre and 27% of puffin surveys. interestingly, piatt also found evidence for a threshold effect in prey density. a maximum correlation in the regression of bird and capelin densities occurred at an intermediate density of capelin; the value of the threshold was higher for murres than it was for puffins. the value of the threshold also varied with background values of prey abundance. erikstad (this volume) also has found scale-dependent correlations between common murres and capelin wintering in the barents sea. in contrast, in the bering sea, woodby (1984) found no indication that rnurre abundance varied in response to the large-scale distribution or abundance of schooling fish. in some cases, most of the individual birds seen in a long-term, wide-ranging study may be concentrated in one or more very large foraging aggregations. for instance, hunt et al. (1985) found 76% of all adelie penguins seen during a 20 day period in one foraging flock and 62% of all cape petrels and 62% of all antarctic fulmars seen over the same period in another foraging flock. in this instance, rare large aggregations of foraging birds associated with unusually large patches of antarctic krill were responsible for the vast majority of foraging seen over an extended period. thus, large patches of prey may be of disproportionate importance to foraging birds. two features are common to the results of most studies of seabirds in relation to prey abundance. first, in all studies where measurement scale was investigated, correlations between these pre dators and their prey were scale dependent and showed stronger correlations at measurement intervals greater than the minimum. consequently, survey designs must be large enough to encompass the largest scales at which multispecies interactions during foraging although seabirds in many cases search for food over very large areas, feeding events occur at the very small scales of individual prey patches (duffy 1983; hunt & schneider 1987). the location of individual prey patches in a comparatively vast area of foraging habitat is particularly challenging if the prey sought are out of sight well beneath the surface. surface manifestations of the presence of prey are important to searching birds; for instance, the presence of feeding birds can often be detected from a long distance (simmons 1972; bayer 1983; gotmark et al. 1986). foraging birds 50 g. l . hunt, j r . can locate feeding birds either directly by observ ing the behavior of nearby birds that have located prey, or indirectly by responding to changes in the behavior of birds moving toward a foraging flock (network foraging, wittenberger & hunt 1985). birds at a colony also obtain information about the location of prey from birds returning to or departing from the colony (e.g. gaston & nettleship 1981). the importance of using foraging birds as indi cators of available food should not be under estimated. in at least some situations, foraging flocks account for the majority of all individuals seen feeding (e.g. duffy 1983; hunt et al. 1985, 1988). the dynamics of these flocks are thus of importance in determining the trophic linkages between seabirds and the marine environment. in particular, t o the extent that birds choose to join others that are already foraging in preference to foraging independently, the first birds to com mence feeding will influence the type of prey taken and the size of patch exploited by the joiners. many foraging flocks consist of more than one species, and the roles played in the flocks differ between species (sealy 1973; hoffman et al. 1981; duffy 1983). some bird species serve as ‘nuclear’ (sealy 1973) or ‘catalyst’ species (hoffman et al. 1981), while others are late joiners or even disrupters of the flocks. in some cases, there is evidence that subsurface foragers drive prey to the surface, which is then available to surface foragers (sealy 1973; grover & olla 1983); in other cases organisms injured by birds foraging deep in the water column drift to the surface where they are taken by nondiving species (hunt et al. 1988; schneider, harrison & hunt 1990). gotmark et al. (1986) found that, for captive gulls foraging on live fish in a shallow pool, fishing success of individual gulls improved with increas ing flock size up to at least eight gulls. the pres ence of numerous foraging birds broke up the protective schooling-’of the fish (shaw 1978). additionally, they found that a greater proportion of captures was from the front or side of the prey when the flock was present than when a single gull was foraging. thus, a variety of synergistic interactions is possible within foraging flocks. interactions between bird species in foraging flocks can also lead to displacement of one species by another. hoffman et al. (1981) describe how large numbers of shearwaters (pufjinus s p p . ) join ing a flock can disrupt foraging by other bird species present. likewise, duffy (1986) provides evidence of common terns displacing roseate terns (s. dougalli) to the edge of dense foraging flocks. larger-sized birds may monopolize the center of foraging flocks where food is densest, but smaller species are still able to forage at the periphery (duffy 1983). kleptoparasitism (hatch 1975) is a highly visible negative effect of joining a flock for the bird that loses its prey. however, the percentage of attacks that result in the attacked bird losing its prey may be fairly small, and thus this penalty for joining a flock may be relatively small compared to the advantages of flock foraging (bayer 1983). marine birds also associate with marine mam mals (evans 1982; burger 1988). evans (1982) cites several examples of birds obtaining prey that whales had concentrated and driven to the surface. he describes instances in which various species of dolphins herding fish near or at the surface were converged upon by gannets (sulu bassana) which then dove in the areas where the prey were concentrated. seabirds near the subantarctic crozet islands join killer whales (orcinus orca) in order to scavenge floating offal (ridoux 1987), but in other areas killer whales are not usually joined by birds (evans 1982; bering sea, hunt personal observation). grey whales (eschrictius robustus) in the bering sea forage on amphipods living in the bottom sedi ment and expel clouds of mud containing amphi pods and fragments of amphipods at the surface. several species of birds take advantage of this otherwise unavailable resource (harrison 1979; obst & hunt 1990). in the chirikov basin, 87% of all red phalaropes (phalaropus fulicarius) and black-legged kittiwakes ( r i m tridactyla) seen foraging were at grey whale mud plumes, sug gesting that, for at least some bird species in this region, whales provide access to a significant source of food (obst & hunt 1990). in many instances, birds and mammals take similar prey, and their presence together may result from independent aggregation to forage on a particular prey (evans 1982). for instance, au & pitman (1986) conclude that the statistically significant positive association between birds and dolphins is the result of a ‘common attraction to food made available by feeding yellowfin tuna (thunnus albacares)’. interestingly, only in the eastern tropical pacific, where surface-foraging schools of yellowfin commonly occur, were birds frequently found with dolphins. elsewhere in the pelagic distribution of marine birds 51 of particular interest for revealing the ability of predators to locate prey. in comparison, when prey are abundant relative t o predators, the extent to which predators seek the densest prey patches appears to be reduced. under these cir cumstances, correlations between avian abun dance and prey abundance are often considerably stronger at large than at small scales of measure ment. the propensity of marine birds to join foraging birds or marine matnmals can influence the extent t o which the abundance of foraging marine birds will correlate with prey abundance at small scales. participation in mixed-species for aging assemblages may result from chance associ ations while pursuing the same prey. although in some cases the result is competitive interactions, in a number of mixed-species flocks interactions are beneficial to one or more species. our know ledge of the extent and persistence of mixed species assemblages is as yet poor. we need to know which species regularly co-occur over wide portions of their ranges and how these species interact when foraging. in many of the areas of study reviewed, we have only begun to answer the larger questions of how the observed interactions with physical and biological aspects of the marine environment influence trophic transfer at the level of populations. beyond this, we have not yet begun to relate the foraging success of the birds to the ultimate question of their survival or repro ductive success. central and western pacific where surface foraging yellowfin are rare, birds were not commonly associated with dolphins. birds also seldom flock with species of dolphins that rarely associate with yellowfin. the flocks associated with the dolphins in the tropical waters of the eastern tropical pacific were generally multispecies aggregations of boobies ( s u b s p p . ) , wedge-tailed shearwaters (puffinus pacificus), sooty terns (sterna fuscata) and jaegers (au & pitman 1988). in contrast to the multispecies flocks of the eastern tropical pacific, au & pitman (1988) found that equa torial and southern subtropical waters supported primarily single-species flocks of sooty terns which were not associated with dolphins. these reports suggest that extreme care must be exer cised in assuming that interactions between seabirds and marine mammals are the result of birds following the mammals in order to locate food. summary over the past decade, marine ornithologists have made considerable progress in relating variations in the pelagic distribution and abundance of marine birds to physical and biological aspects of the marine environment. attendance of birds at fronts in the open sea and at the ice edge are well documented, and at least in some cases, water column stratification is important. however, for most of these features, we have little information on their overall significance for trophic transfer to marine birds. in at least one case, the inter domain fronts of the southeastern bering sea, fronts were not attended by higher numbers of birds than expected by chance. although we assume that birds attend various physical features because prey is either more abundant or more available at them, we have relatively few data on the distribution of prey at an appropriate measurement scale. those studies investigating t h e spatial and numerical concordance between marine birds and their prey have found some instances of strong concordances and others in which prey distribution and abundance were of little or no value in predicting bird abundance. this is an area of study in which we need more information linking birds, prey and physical fea tures. additionally, study of systems in which prey abundance has been severely reduced (such as the barents sea capelin fishery) and predators are abundant relative to prey stocks should be references abrams. r . w . & lutjeharms j . r. e. 1988: relationships between seabirds and meso-scale hydrographic features in the agulhes current retroflection region. pp. 991-996 in oulette, h . (ed.): proc. x i x i n l . om. congr. ottawa, 1986. ainley, d. g. & boekelheide, r. i.. 1984: an ecological com parison of oceanic seabird communities of the south pacific ocean. stud. avian biology 8 . 2-23. ainley, d. g. &jacobs, s . s . 1981: sea-bird affinities for ocean and ice boundaries in the antarctic. deep-seu res. 28a. 117.3-1185. ainley, d. g., fraser, w . r . , sullivan, c. w . , torres, j . j . , hopkins, t. l. & smith, w . 0. 1986: antarctic mesopelagic micronekton: evidence from seabirds that pack ice affcct5 community structure. science 232. 847-849. alexander, v . & chapman, t. 1y81: the role of epontic com munities in bering sca ice. pp. 773-780 in hood, d. w. & caldcr, j. a. (eds.): the eastern bering seu shelf: oceano graphy and resources. vol. 11, noaa, washingron, d.c. alexander, v. & niebauer, h . j . 1981: oceanography of the eastern bering sea ice-edge zone in spring. limnology and oceanography 26, 1 1 11-1125. 5 2 g. l . hunt, j r . ashmole, n. p. 1971: seabird ecology and the marine environ ment. pp. 223-286 in farner d . s . & king j . r. (eds.): avian biol. 1 . academic press, new york. au, d. w. k. & pitman, r. l. 1986: seabird interactions with dolphins and tuna in the eastern tropical pacific. condor 88, 304-317. au. d . w. k. & pitman, r . l. 1988: seabird relationships with tropical tunas and dolphins. pp. 1 7 4 2 1 2 in burger, j. (ed.): seabirds and other marine uertebrates. columbia u. press, new york. barroclough, w. e . , lebrasseur, r. j . & kennedy, 0. d . 1969: shallow scattering layer in the subantarctic pacific ocean: detection by high-frequency echosounder. science 166,611 613. bayer, r. d. 1983: black-leggcd kittiwake feeding flocks in alaska: selfish/reciprocal altruistic flocks? j . field ornithol. 5 4 , 196199. belopol’skii, l. 0. 1961: ecology of sea colony birds of the barents sea. israel prog. sci. transl. jerusalem. birkhead, t. r . 1976: effects of sea conditions o n rates at which guillemots feed chicks. brit. birds 69, 490-492. birkhead, t. r. & furness, r. w. 1985: regulation of seabird populations. pp. 147-167 in sibley, r . m. & smith, r . h . (eds.): behauioral ecology; ecological consequences of adapt ive behauior. blackwell, london. birt, v . l . , birt, t. p., goulet, d . , cairns, d. k. & montc vecchi, w . a . 1987: ashmole’s halo: direct evidence for prey depletion by a seabird. mar. ecol. prog. ser. 40, 205-208. bradstreet, m. s . w. 1979: thick-billed murres and black guillemots in the barrow strait area, n . w . t . , during spring: distribution and habitat use. can. j . z o o / . 57, 178% 1802. bradstreet, m . s. w . 1980: thick-billed murres and black guillemots in the barrow strait area, n.w.t., during spring: diets and food availability along ice edges. can. j . zool. 58, 2120-2140. bradstreet, m. s. w. 1982: occurrence, habitat use and behavior of seabirds, marine mammals and arctic cod at the pond inlet ice edge. arctic 35, 28-40. bradstreet, m. s. w. 1988: importance of ice edges t o high arctic seabirds. pp. 997-1000 in oulette, h. (ed.): proc. xix int. o m . congr., ottawa, 1986. bradstreet, m. s. w . & cross, w. e . 1982: trophic relation ships at high arctic ice edges. arctic 35, 1-12. braun, b. m . & gaskin, d. e . 1982: feeding ecology of nonbrceding populations of larids off deer island, new brunswick. auk 99, 67-76. briggs, k. t . & chu, e . w. 1986: sooty shearwaters off cali fornia: distribution, abundance and habitat usc. condor 88, 35s364. briggs, k. t . , ainley, d . g . , spear, l. b . , adams, p. b. & smith, s . e. 1988: feeding of two alcids at central california upwellings. pp. 982-990 in oulette, h . (ed.): proc. xix int. om. congr., ottawa, 1986. briggs, k . t . , dettman, k. f., lewis, d . b. & tyler, w. b. 1984: phalarope feeding in relation to autumn upwelling off california. pp. 51-62 in nettleship, d. n., sanger, g . a . & springer, p. f. (eds.): marine birds: their feeding ecology and commercialfisheries relatiomhips. can. wildl. serv., ottawa. briggs, k. t., tyler, w . b., lewis d . b. & carlson, d . r. 1987: bird communities at sea off california: 19751983. stud. avian biol. 1 1 , 1-74. brown, r . g . b . 1 9 7 9 seabirds of the senegal upwelling and adjacent waters. 166 121, 283-292. in burger, j., o h , b . l . & winn, h . e . (eds.): behavior of marine animals 4 . plenum press, new york. brown, r . g . b . 1980b: the pelagic ecology of seabirds. tram. linnaean sac. new york 9 , 15-22, brown, r. g . b. 1988: zooplankton patchiness and scabird distributions. pp. 1001-1009 in oulette, h . (ed.): proc. xix int. o m . congr., ottawa, 1986. brown, r. g. b. & gaskin, d. e. 1988: the pelagic ecology of the grey and red-necked phalaropes phalaropuc fulicarius and p. lobatus in the bay of fundy, eastern canada. ibis 130, 234250. brown, r. g. b . & nettleship, d. n. 1981: the biological significance of polynyas to arctic colonial seabirds. pp. 59-65 in stirling, i . & cleater, h . (cds.): polynyas in the canadian arctic. can. wildl. serv. occ. pap. 45. buckley, j . r . , gammelsr0d, t., johannssen, j . a , , johannssen, 0. m. & r ~ e d , l. p . 1979: upwelling: oceanic structure at the edge of the arctic ice pack in winter. science 203, 165-167. burger, j . 1988: seabirds and ocher marine vertebrates. colum bia u . press, new york. cadee, g. c. 1981: seabird observations between rotterdam and the equatorial atlantic. ibis 11 7, 339-356. cairns, d . k. & schneider, d . c. 1990: hotspots in cold water: feeding hahitat selection by thick-billed murres. stud. avian biology (in press). coachman, l. k. 1986: circulation, water masses, and fluxes on the southeastern bering sca shelf. cant. shelfres. 5 , 23 108. coachman, l. k . , aagaard, k. & tripp, r . b. 1975: bering strait: the regional physical oceanography. u. washington press, seattle. 172 pp. cooney, r. t. & coyle, k . 0 . 1982: trophic implications of cross-shelf copepod distributions in the southeastern bering sea. mar. biol. 70, 187-196. coyle, k. 0. & cooney, r . t. 1988: estimating carbon flux to pelagic grazers in the ice-edge zone of the eastern bering sea. mar. biol. 98, 299-306. croxall, j . p . , davis, r. w. & o’connell, m. j . 1988: diving patterns in relation t o diet of gentoo and macaroni penguins at south georgia. condor 90, 157-167. croxall, j. p., everson, i . , koozman, g. l., ricketts, c. & davis, r . w . 1985: fur seal diving behavior in relation to vertical distribution of krill. j . anim. ecol. 54, 1-8. divoky, g. j . 1979: sea ice as a factor in seabird distribution and ecology in the beaufort, chukchi and bering seas. pp. 9-18 in bartoneck, j . c. & nettleship, d. n . (eds.): con servation of marine birds of northern north america. u . s . fish and wildlife service research report 11. divoky, g . j . 1981: birds and the ice-edge ecosystem in the bering sea. pp. 799-804 in hood, d . w. & calder, j . a . (eds.): the eastern bering sea shelf oceanography and resources. val. 11, n o a a , washington, d . c . duffy. d . c. 1983: the foraging ecology of peruvian seabirds. auk 100, 80c-810. duffy, d . c. 1986: foraging at patches: interactings between common and roseate terns. ornis scand. 17, 47-52. dunbar, m. j. 1981: physical causes and biological significance of polynyas and other open water in sea ice. pp. 29-43 in stirling, i . & cleator, €i. (eds.): polynyas in the canadian arctic. can. wildl. serv. occ. pap. 45. dunn, e . k. 1973: changes in fishing ability of terns associated with windspeed and sea surface conditions. nature 244, 52& 521. brown, r . g. b. 1980a: seabirds as marine animals. pp. 1-39 eppley, z . a . & harrison, n. m. 1985: distribution of marine pelagic distribution of marine birds 5 3 birds off wilkes land, february 1985. u . s . antarctic journal i985 review, 164166. evans, p. g . h . 1982: associations between seabirds and cet aceans: a review. mammal. rev. 12, 187-206. everson, i. 1983: variations in vertical distribution and density of krill swarms in thc vicinity of south georgia. memoirs of nat’l. instit. polar res. tokyo special issue 27, 84-92. ford, r. g., wiens, j . a , , heinemann, d . & hunt, g . l. 1982: modelling the sensitivity of colonially breeding marine birds to oil spills: guillemot and kittiwake populations on the pribilof islands, bering sea. j . appl. ecol. 19, 1-31. fraser, w . r . & ainley, d. g. 1986: ice edges and seabird occurrence in antarctica. bioscience 36, 256263. furness, r . w. & birkhead, t. r . 1984: seabird colony distri butions suggest competition for food supplies during the breeding season. nature lond. 311, 655-656. garrison, d . l., sullivan, c . w. & ackley, s. f. 1986: sea ice microbial communitics in antarctica. bioscience 36, 24% 250. gaston, a . j . & nettleship, d. n. 1981: the thick-billed murres of prince lcopold island. can. wildl. seru. monogr. ser. 6 , 1-350. gaston, a. j . , chapdclainc, g. & noble, d . 1983: the growth of thick-billed murre chicks at colonies in hudson strait: interand intra-colony variation. can. j . zool. 61, 2465 2475. gotmark, f., winkler, d . w. & andersson, m. 1986: flock feeding on fish schools increases individual success in gulls. nature lond. 319, 58y-591. grover, j . j . & olla, b . l. 1983: the role of the rhinocerous auklet (cerorhinea monocerata) in mixed species feeding assemblages of seabirds in the strait of juan de fuca, wash ington. auk 100, 979982. gulliksen, b. 1984: under-ice fauna from svalbard waters. sarsia 69, 11-23. guzman, j . r . & myers, m. t. 1987: ecology and behavior of southern hemisphere shearwaters (genus pufinus) when over the outer continental shelf of the gulf of alsaka and bering sea during the northern summer (1975-1976). outer continental shelf environmental assessment program final report 5 4 , n o a a , washington, d . c . , 571-682. haney, j . c . 1985: wintering phalaropes off the southeastern united states: application of remotc sensing imagery to scabird habitat analysis at oceanic fronts. j . field. ornith. 5 6 , 321-333. haney, j . c. & mcgillivary, p. a . 1985a: aggregations of cory’s shearwaters (caloneatris diomedea) at gulf stream fronts. wilson bull. 97, 191-200. haney, j . c. & mcgillivary, p. a . 1985h: midshelf fronts in the south atlantic bight and their influence on seabird distribution and scasonal abundance. biol. oceanogr. 3,401 430. harder, w. 1968: reactions of plankton organisms to water stratification. limnol. and oceanogr. 13, 156-168. harrison, c . s . 1979: the association of marine birds and fccding grey whales. condor 81, 93-95. hatch, j. j . 1975: piracy of laughing gulls larus atricilla: an example of the selfish group. ibis 117, 357-365. heinemann, d., hunt, g. & everson, 1. 1989: the distributions of marine avian predators and their prey, euphausia superba, in bransfield strait and southern drake passage, antarctica. mar. ecol. prog. ser. 5 8 , 3-16. hoffman, w., heinemann, d. & wiens, j . a . 1981: the ecology of seabird feeding flocks in alaska. auk 98, 437-456. hunt, g . l. & butler, j. l. 1980: reproductive ecology of western gulls and xantus’ murrelets with respect to food resources in the southern california bight. cal cofl rept. 21, 62-67, hunt, g . l. & schneider, d. c. 1987: scale-dependent pro cesses in physical and biological environment of marine birds. pp. 7-41 in croxall, j. p. (ed.): seabirds:feeding biology and role in marine ecosystems. cambridge u. press, cambridge. hunt, g. l., eppley, z. a. & schncider, d. c. 1986: repro ductive performance of seabirds: the importance of popu lation and colony size. auk 103, 306317. hunt, g. l., everson, i . , veit, r. r. & heinemann, d. 1985: distribution of marine birds and their prey in bransfield strait and southern drake passage. ant. j. u . s . 19, 166-168. hunt, g . l., gould, p . , forsell, d. & peterson, h . 1981: pelagic distribution of marine birds in the eastern bering sea. pp. 689-717 in hood, d. w. & caldcr, j . a . (cds.): the eastern bering sea shelf: oceanography and resources. vol. 11, n o a a , washington, d. c. hunt, g. l., harrison, n. m. & cooncy, t. 1990: foraging of lcast auklcts: the influence of hydrographic structure and prey abundance. stud. avian biology (in press). hunt, g. l., harrison, n. m., hamner, w. m. & obst, b. s. 1988: observations of a mixed-species flock of birds foraging on euphausiids near st. mathew island, bering sea. auk 105, 345-349. iverson, r . l., coachman, l. k., cooney, r . t . , english, t . s., goering, j. j . , hunt, g . l . , maccauley, m. c., mcroy, c. p., reeburg, w. s. & whitledge, t . e . 1979: ecological significance of fronts in the soutbcastcrn bcring sca. pp. 437 465 in livingston, r . l. (ed.): ecologicalproce.wes in coastal and marine systems. plenum press, new york. joiris, c. 1983: winter distributions of seabirds in the north sea: an oceanological interpretation. gefaut 73, 107 123. kinder, t . h . & schumacher, s. d. 1981: circulation over the continental shelf of the southeastern bcring sea. pp. 53-75 in hood, d . w. & calder, j. a . (eds.): the eastern bering sea shelf: oceanography and resources. vol. i . , noaa, washington, d . c . kinder, t. h . , hunt, g . l., schneidcr, d. & schumacher, j . d. 1983: correlations between seabirds and oceanic fronts around the pribilof islands, alaska. estuar. coast. shelf sci. 16, 309-319. lasker, r . 1979: factors contributing to variable recruitment of the northern anchovy (engraulis mordax) in the california current: contrasting years 1975 through 1978. ices sym posium on the early life history of fish. marine biological laboratory, woods hole, ma. loeb, v. j. & shulenberger, e . 1987: vertical distributions and relations of euphausiid populations off elephant island, march 1984. polar biol. 7, 363-374. mauchline, j . 1980: the biology of mysids and euphausiids. a d v . mar. biol. 18, 527-542. mclaren, p. l. 1982: spring migration and habitat use by seabirds in eastern lancaster sound and western baffin bay. arctic 35, 86111. mcroy, c. p. & goering, j . j. 1974: the influence of ice on the primary productivity of the bering sea. pp. 403-421 in hood, d. w. & kelly, e. j . (eds.): oceanography of the bering sea. imtitute of marine science (alaska) occ. publ. l. miiller-kargcr, f. & alcxander, v. 1987: nitrogen dynamics in a marginal sea-ice zone. cont. shelf res. 7, 805-823. nettleship, d. n., birkhead, t. r . & gaston, a. j . 1984: breeding of arctic seabirds in unusual ice years: the thick 54 g. l . hunt, jr. billed murre uria lomuia in 1978. bedford imtitule of oceanography reuiew 1984, 35-38, niebauer, h . j . & alexander, v. 1985: oceanographic frontal structure and biological production at an ice edge. cont. shelf res. 4 , 367-388. obst, b. s. 1985: densities of antarctic seabirds at sea and the presence of the krill euphausiu superba. auk 102,54&549. obst, b. s . & hunt, g . l. 1990: marinc birds foraging at grey whale mud plumes in the bering sea. auk (in press). orr, c. d., word, r . m. p . , williams, n. a. & brown, r. g. b . 1982: migration pattcrns of rcd and northern phalaropes in southwest davis strait and in the northern labrador sea. wilson bull. 94, 303-312. piatt, j. f. 1990: the aggregativc response of common murres and atlantic puffins to schools of capelin. stud. auian biology (in press). pcterman, r. m. & bradford, m. j . 1987: wind spccd and mortality rate of a marine fish, the northern anchovy (engraulis mordax). science 235, 354356. powers, k. d . 1983: pelagic distributions of birds off the north eastern united states. national oceanic and atmospheric administration, technical memorandum nmfs-finec-27. woods hole, mass. 201 pp. kidoux. v. 1987: feeding association between seabirds and killer whales, orcinus orca, around subantarctic crozct islands. can. j . zool. 6 5 , 2113-2115. safinn, c . & burgcr, j 1985: common tern foraging: seasonal lrcnds in prcy fish densities and compctition with bluefish. ecol. 66, 1457-1463. safina, c. & burger, j. 1988: ecological dynamics among prey fish, blucfish. and foraging common terns in an atlantic coastal systcm. pp. 95-173 in burger, j . (cd.): seabirds & other marine uertebrates. columbia u . press, new york. salt, g . w. & willard, d . c. 1971: the hunting behavior and success of forster’s tern. ecol. 5 2 , 989-998. schandelmeier, l. & alexander, v. 1981: an analysis of thc influence of ice on spring phytoplankton structure in the southeast bering sea. limnol. and oceanogr. 26, 935-y43. schneider, d. c. 1982: fronts and seabird aggregations in the southeastern bering sea. mar. ecol. prog. ser. 10. 101 103. schncidcr, d . c. & duffy. d . c. 1985: scale-dependent varia bility in wabird abundance. mur. ecol. prog. ser. 25. 21 i 218. schneider, d . c. & ilunt, g . l. 1982: carbon flux to seabirds in water with different mixing regimes in the southeastern bering sea. mar. biol. 6 7 . 337-344. schneider, d. c . & ppdtt, 1 . f. 1986: scale-dependent cor relation of seabirds with schooling fish in a coastal ecosystem. mar. ecol. prog. ser. 3 2 , 237-246. schneider. d . c., duffy, d. c. & hunt, g . l., jr. 1988: cross shelf gradients in the abundance of pelagic birds. pp. 9 7 6 981 inoulcttc, h . (cd.): pruc. x / x l n t . o m . congr., ottawa, 1986. schncidcr, d . c., harriwn, n. m . & hunt, g. l. 1987: vari ation in thc occurrcncc of marine birds at fronts in the bering sea. esluar. coast. shelf sci. 25, 135-141. schneider, d. c , , harrison. n. m. & hunt. g . l. 1990: scabird diet at a hathymetrically dctcrmincd conflucncc near thc pribilof islands, alaska. stud. auian biology (in press). schneider, d. c . , hunt, g . l. & harrison, n. m. 1986: mass and energy transfer to seabirds in the southeastern bering sea. cont. shelf. res. 5,241-257. schneider, d . c . , pierotti, r . & threlfall, w. 1990: alcid patchiness and flight directions near a colony in castcrn new foundland. stud. auian biology (in press). scaly, s. g. 1973: interspecific feeding assemblages of marine birds off british columbia. auk 90, 796802. shaw, e. 1978: schooling fishes. a m . sci. 66, 166175. shuntov, v. p. 1974: seabirds and the biological structure of the occan. washington, d.c.: u . s . d e p t . ofcommerce, nar’l. tech. l n f . sero. (ntis-tt-74-55032). simmons, k. e . l. 1972: some adaptive features of seabird plumage types. brit. birds 6 5 , 405-479, 51cl521. smith, s. l . , smith, w. o., codispotti, l. a . &wilson, d. l. 1985: biological observations in the marginal ice zone of the east greenland sea. j . mar. res. 43, 693-717. smith, w. 0. 1987: phytoplankton dynamics i n marginal ice zones. oceanogr. mar. biol. ann. rev. 25, 11-38. smith, w. 0. & nelson, d . m . 1985: phyloplankton bloom produced by a receding ice edge in the ross sea: spatial cohcrcnce with the density field. science 227, 163-166. smith, w. 0. & nelson, d . m. 1986: importance of icc cdge phytoplankton production in the southern occan. bioscience 36, 251-257. springer, a . m. & roseneau, d . g . 19x5: copepod-based food webs: auklets and occanography in the bering sea. mar. ecol. prog. ser. 21,229-231. springer, a. m., murphy, e. c., roscncau, d. g . , cooper. b. p. & mcroy, c . p. 1987: seabird food wcbsin the northcrn bering sea. cont. shelfres. 7, 895-911. springcr, a. m., roscneau, d. g., murphy, e. c . &springer, m. i . 1984: environmental controls of marine food webs: food habits of seabirds in the eastern chukchi sea. can. j. fish. aquat. sci. 4 1 , 1202-1215. stirling, 1 . 1980: the biological importance of polynyas in the canadian arctic. arctic 33, 303-315. stonchouse, b. 1967: occurrence and cffccts of open wnlcr in mcmurdo sound, antarctica, during winter and carly spring. trivclpiece, w. z . , benatson. j . l . , trivclpiccc, s. g. & volkman, n. j . 1986: foraging behavior of gentoo and chinstrap penguins as determined by new radiotclemetry techniques. auk 103, 777-781. vermccr, k., szabo, i. & greisman, p. 19x7: the relationship between plankton-feeding bonaparte’s and mew gulls and tidal upwelling at active pass, british columbia. j . plankton res. 9, 483-501. veit, r. r. 1985: long-tailed jacgcrs wintcring along thc falk land current. amer. birds 39. 87.3-878. walsh, j . j . & mcroy, c. p . 1986: ecosystem analysis in the southeastern bering sea. conr. shelf res. 5 . 259-288. wanless, s., harris, m. p. & morris, j . a . 1985: radio moni toring as a methiid for estimating time budgets of guillcmots uriu aulge. bird study 32, 17cl-175. wittenberger, j . f . & hunt, g . l. 1985: the adaptive sig nificance of coloniality i n birds. pp. 1-78 in farner, d . s . , king, j . r. & parkes, k . c. (eds.): auian b i d . 8 . academic press, orlando. woodby, d. a . 1984: the april distribution of murres and prey patches in the southeastern bering sca. limnol. oceanogr. 2y. 181-188. pcjl. res. 13, 775-778. revisiting perceptions and evolving culture: a community dialogue on women in polar research perspective revisiting perceptions and evolving culture: a community dialogue on women in polar research sandra starkweather a, m. seagb, o. leec & a. poped acooperative institute for research in environmental sciences, university of colorado, boulder, co, usa; bscott polar research institute, university of cambridge, cambridge, uk; cinternational arctic research center, university of alaska fairbanks, fairbanks, ak, usa; dinternational arctic science committee, akureyri, iceland abstract women have made outstanding contributions to polar research in recent decades, though full engagement may be hindered by persistent inequities, including notably the prevalence of workplace harassment. remote field settings, such as those pervasive in polar research, have been identified as particularly susceptible to cultures of harassment. it was therefore timely at the polar 2018 open science conference in davos, switzerland, to convene a discussion focused on women’s perspectives and experiences. a panel discussion—“from entering the field to taking the helm: perspectives of women in polar research”—took place on 20 june 2018 and featured five women undertaking work from marine biotechnology to organizational leadership, across career levels. over 300 conference attendees joined the lunchtime panel. the panellists’ perspectives on historical barriers, current challenges and future prospects revealed that while challenges persist, experiences vary greatly. audience engagement underscored the need to sustain dialogue at polar meetings, to bring visibility to the statistics related to workplace harassment and to encourage polar science organizations to assume leadership on promoting equitable workplace culture. keywords gender; equity; harassment; culture; science; open science conference abbreviations iasc: international arctic science committee; scar: scientific committee on antarctic research background women’s participation in polar research has grown steadily as cultural and institutional barriers to their participation have decreased (rosner 2009; hulbe et al. 2010; carey et al. 2016). however, in spite of decades of progress, including women’s ascension to leadership at key institutions, challenges persist. the high prestige of work associated with remote field sites, long vessel cruises and sustained studies within northern communities has often been accompanied by high barriers to female participation. twentiethcentury policies barring women from polar field sites (seag 2017) have left a legacy of field cultures centred around masculine norms (rosner 2009; glasberg 2012; carey et al. 2016). today, as hard barriers are falling, these norms need revisiting, and expected codes of conduct in field sites must be clearly articulated and enforced (starkweather et al. 2017). a growing body of evidence, including the safe study (clancy et al. 2014), has recently underscored the much more damaging impact of harassment directed disproportionally at women participating in fieldwork, ranging from the rare but most explicit forms of violence to subtle but more pervasive gender harassment. polar research is not immune to these threats to safety and inclusivity (bell & koenig 2017; waldman 2018). recently, nelson et al. (2017) have documented the prevalence of career exits due to negative experiences with scientific field programmes, particularly those that do not enforce codes of conduct. other scholars have emphasized that female scientists can fail to achieve the “visibility” of male peers, even when their work is equally impactful (e.g., oreskes 1996). the combined effects of these stressors may account for a greater portion of the so-called “leaky pipeline” effect (goulden et al. 2011), describing the progressive loss of female talent from the science labour pool, than has been previously understood (srt 2018). last month, the us national academies of science, engineering, and medicine released the results of a sweeping, multi-year study on harassment in the sciences (nasem 2018). their study found that between 20% and 50% of female students in us science, engineering and medicine reported having experienced harassing behaviour perpetrated by staff or faculty; more than 50% of faculty also said they had experienced harassment. lgbtq women and women of colour were more likely than their straight, white counterparts to have been harassed, and women of colour were more likely to report feeling unsafe because of their gender. the study also recognized a problematic dearth of data. contact sandra starkweather sandy.starkweather@noaa.gov cooperative institute for research in environmental sciences, university of colorado, ucb 216, boulder, co 80309, usa polar research 2018, vol. 37, 1529529 https://doi.org/10.1080/17518369.2018.1529529 © 2018 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0001-7369-1891 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2018.1529529&domain=pdf this dearth of data is true in the polar regions too, but the recent work of nash et al. (2018) provides an important first look. their survey of researchers in the australian antarctic program revealed that 64% of female participants experienced harassment, and, like the safe study, found that these incidents go largely unreported. meanwhile, media reports concerning female geologists working under the us antarctic program (scoles 2018) put a harrowing face on how such harassment can proceed unchecked in remote and isolated locations. data from nonwestern countries and data on arctic research are even scarcer. given these facts, a fresh round of examinations of polar work cultures is called for. the international polar year 2007–09 opened many doors to researchers from around the world (krupnik et al. 2011), including women, so it was timely at the polar 2018 open science conference for a discussion focused on women’s experiences in polar research. the panel discussion—“from entering the field to taking the helm: perspectives of women in polar research”—took place on 20 june and featured five women in disciplines ranging from marine biotechnology to organizational leadership to history of science. while the “taking the helm” event centred on the perspectives of women, it was important to the organizers to avoid essentializing “women” and further to recognize that gender is nonbinary. further, it was important to recognize that many intersecting identities can result in overlapping challenges that require specific attention. panellists represented plural intersecting factors spanning career levels, research discipline, professional roles and national and ethnic identities. from the event the event drew more than 300 participants representing 32 countries, who engaged in a vibrant, interactive dialogue with the panellists following interview questions by independent journalist hannah hoag. hoag’s questions explored aspects of the panellists’ experiences including: landmark achievements; challenges related to retention, mentoring and the #metoo movement in science; and redefining leadership. hoag introduced the discussion by acknowledging her surprise at the relatively recent history of women’s inroads to polar work and the leading achievements of some of the panellists. hongkum lee, a former director of the korean polar research institute, was among the first women to assume the leadership of any polar institute. during her tenure as director (2007–2013), she oversaw the completion of korea’s first research icebreaker, aaron, and the jangbogo antarctic research station in terra nova bay. lee noted that her position empowered her to budget for appropriately sized field equipment for female participants—a key safety advancement. susan barr, iasc’s first female leader, characterized her field experiences as overwhelmingly positive, even as she was blazing trails. while taking on a role that required extensive fieldwork in svalbard did expose her to improperly sized equipment and scepticism related to her abilities to operate firearms or outboard motors, she met these hurdles with a sense of humour. morgan seag, a doctoral candidate in geography studying women’s advancements into antarctic research, shared that her work was inspired by senior female researchers like these “who changed my conception of what my future could look like. i had assumed that my sixties and seventies would involve hammocks and grandbabies—these powerful women [in antarctica] showed me how narrow that idea was. i could [like them] be camping on the ice sheet, making discoveries.” seag went on to observe that the antarctic culture for female researchers is still mixed in spite of these pioneers’ contributions. in response to an audience question about sexualization of women in the field, she noted the enduring prevalence of comparing and “rating” female field team members on their attractiveness across field sites on the continent. challenges are by no means limited to field sites. arctic researcher colleen strawhacker, an archaeologist who works with indigenous communities in both alaska and the american south-west, recounted her own experiences with bullying during proposal preparation at the hands of senior male investigators, which caused her to note: “you can either fight for a seat at the table or build your own table. both are exhausting.” while she stood her ground against the bullying behaviour, she fears the type of retaliation that could await her through anonymous community processes like proposal or publication review. these anxieties were echoed by an audience member who had taken similar positions. these and other challenges prompted hoag to turn to the panellists for their ideas about how to move forward. chandy nath, the new executive director of scar, shared her view that “we need to reimagine what leadership looks like”. she and others acknowledged that there can be an unconscious image in our heads when we think about polar research, i.e., the frosty beard, and that it takes deliberate efforts to broaden that view. or as others have noted: “if you aren’t being consciously inclusive, you are likely being unconsciously exclusive.” all panellists agreed that early career researchers should not let perceptions about barriers stand in their way. audience questions honed in on and amplified those sentiments of the panellists focused on barriers and challenges. multiple audience comments also focused on the low numbers of men present in the audience, who accounted for about 5% of the 2 s. starkweather et al. participants. even if stemming from positive intentions, such as to allow women to have their own space, a lack of male participation in these conversations was viewed as particularly problematic related to the road towards creating more inclusive polar research cultures. the event generated a strong response across social media platforms, where hundreds—both inside and outside the room—participated in the virtual conversation following the hashtag #polarwomen2018, eventually reaching a social media audience of more than 800 000 panellists’ perspectives were augmented through the development of an instagram effort eliciting input through a series of questions. the instagram account has grown a steady following from zero to over 600 followers in 10 weeks. the resulting women in polar science compilation, which currently numbers 50 profiles, continues to enrich our understanding of the plurality of experiences and achievements of women in polar research, and highlights the potentials and aspirations of a generation of women poised to impact the world. reflected in these profiles are the joys of collegiality and accomplishment in positive work environments; the importance of believing in yourself, following your instincts, supporting colleagues and not letting biases stand in your way; and a clear love of polar environments and people. moving forward the innovations required to address the next generation of polar research questions surpass the bounds of the physical, chemical or biological sciences alone. future challenges will require systems thinking, inclusive collaboration and the dismantling of socially enmeshed barriers to progress. what better way to prepare a generation of scientists to meet the challenges posed by rapid ecological change, muchneeded interdisciplinary work and the paradigmatic shift towards knowledge co-production than through raising cultural awareness and equity within our own ranks? the overwhelmingly strong presence of early career researchers at the event suggests that there will be a continued demand to sustain inclusivity dialogues; some senior researchers were dismayed that “we still need to have these conversations”. these types of generational differences may reflect shifting norms, or they may reflect a subtler selection bias whereby certain types of adaptive strategies, natural to some and quite foreign to others, improve survivorship in research settings (e.g., mcnutt 2017; willenbring 2018). as cheryl rosa of the us arctic research commission notes in her instagram profile, “[i]t would be nice not to need any strategy” to succeed as a woman in polar research. will the future impact of women in polar research be limited by their ability to strategize around gender barriers? or is our community willing to evolve culturally, to dismantle those barriers and broaden our image of who contributes to scientific excellence and how? the answer lies in part with our institutions, including international science bodies like iasc and scar. cultural shifts take time and deliberate remedies. the us national academies of sciences, engineering, and medicine study recognized that solutions to harassment in the geosciences will require a “system wide change to the culture and climate”. system-wide change of this type starts with dialogue, an important objective of the “taking the helm” event. yet without stronger participation from male colleagues, system-wide change will not advance. iasc executive secretary allen pope, a coorganizer for the event, asked on twitter: “do we have sufficient ‘buy-in’ to the staggering statistics about harassment to make a change?” each of us who has personally experienced such harassment might reflect on the value of sharing these experiences more openly to build such buy-in. further, we need to promote the types of culture and climate surveys that reveal the experiences of researchers in our proximal settings, including those who wish to remain anonymous. polar institutions like iasc and scar could play key roles in supporting surveys to establish a baseline of experiences against which we could formulate remedies and measure progress. in the meantime, it is imperative that organizations like the forum of arctic research operators and the council of managers of national antarctic programs continue to grow a role for themselves in preventing and responding to sexual harassment in polar field settings. a beneficial starting point, as raised through the social media commentary, would be to help make acceptable norms of behaviour well understood and enforced. indigenous participants were notably underrepresented at polar 2018 for a variety of reasons and absent from the panel itself. strawhacker challenged the audience to investigate why these meetings are not more relevant for, or accessible to, indigenous communities. returning to the starting premise that intersectionality provides a valuable frame for cultural examination, co-organizer renuka badhe, of the european polar board, noted during closing remarks at the event that there are many other minoritized groups who would benefit from an expanding dialogue about inclusivity in polar research. organizations like iasc and scar should consider ways to better integrate inclusivity dialogues into their meeting programmes, encouraging all attendees to participate, and to develop and enforce codes of conduct for their own organizations. if there was a unifying aspect of the “taking the helm” event, it was a shared aspiration to see a future for polar research that is ever more diverse, respectful and inclusive for all, one that supports a polar research 3 vibrant community of researchers through all career stages and enables them to rise to the height of their potential. our collective efforts to better understand polar regions are impaired when we are not inclusive, and, at this critical time, we can’t afford that. let’s work together to evolve a more positive work culture for all so that the adaptive strategies that women, people of colour and others have developed to cope with discrimination can become a thing of the past. acknowledgements we would like to thank our sponsors for their support of the “taking the helm” event: antarctic and southern ocean coalition, arctic research consortium of the usa, iasc, international association of cryospheric sciences, international glaciological society, ocean expeditions, ltd., tinker muse prize, usa arctic research commission and an anonymous private donor. we would also like to thank our moderator, panellists and volunteer coordinator meredith lavalley. disclosure statement no potential conflict of interest was reported by the authors. orcid sandra starkweather http://orcid.org/0000-0001-73691891 references bell r.e. & koenig l.s. 2017. harassment in science is real. science 358, 1223. carey m., jackson m., antonello a. & rushing j. 2016. glaciers, gender, and science: a feminist glaciology framework for global environmental change research. progress in human geography 40, 770–793. clancy k., nelson r., rutherford j. & hinde k. 2014. survey of academic field experiences (safe): trainees report harassment and assault. plos one 9, e102172, 10.1371/journal.pone.0102172. glasberg e. 2012. antarctica as cultural critique: the gendered politics of scientific exploration and climate change. new york: palgrave macmillan. goulden m., mason m.a. & frasch k. 2011. keeping women in the science pipeline. annals of the american academy of political and social science 638, 141–162. hulbe c., wang w. & ommanney s. 2010. women in glaciology, a historical perspective. journal of glaciology 56, 944–964. krupnik i., allison r., bell r., cutler p., hik d., lópezmartinez j., rachold v., sarukhanian e. & summerhayes c. (eds.) 2011. understanding earth’s polar challenges: international polar year 2007-208, summary by the ipy joint committee. rovaniemi, finland: university of the arctic. mcnutt m. 2017. welcome in our field: attracting the best and brightest. plenary session talk at 2017 aquatic sciences meeting, honolulu, hi. nasem (national academies of sciences, engineering, and medicine) 2018. sexual harassment of women: climate, culture, and consequences in academic sciences, engineering, and medicine. washington, dc: the national academies press. nash m., lea m.-a., shaw j., king m., bax n. & nielsen h. 2018. findings from a national survey on gender equity in australian antarctic science. poster presented at the polar 2018 open science conference, 15–26 june, davos, switzerland. nelson r., rutherford j., hinde k. & clancy k. 2017. signaling safety: characterizing fieldwork experiences and their implications for career trajectories. american anthropologist 119, 710–722. oreskes n. 1996. objectivity or heroism? on the invisibility of women in science. osiris 11, 87–113. rosner v. 2009. gender and polar studies: mapping the terrain. signs: journal of women in culture and society 34, 489–494. scoles s. 2018. the harassment problem in scientific dream jobs. outside online. accessed online at https://www. outsideonline.com/2300656/harassment-problemscientific-dream-jobs?utm_content=bufferf4f3d&utm_ medium=social&utm_source=twitter&utm_campaign= tweet on 7 september 2018. seag m. 2017. women need not apply: gendered institutional change in antarctica and outer space. the polar journal 7, 319–335. srt (subcommittee on research and technology; 115th congress) 2018. hearing—a review of sexual harassment and misconduct in science. accessed online at https:// science.house.gov/legislation/hearings/subcommitteeresearch-and-technology-hearing-review-sexualharassment-and on 7 september 2018. starkweather s., derry k. & crain r. 2017. leveling the field: the role of preparation, leadership, and networks in empowering minoritized participants. presented at the american geophysical union fall meeting, 11–15 december, new orleans. waldman m. 2018. boston university rejects geologist david marchant’s appeal of termination. scientific community, science. accessed online at http://www. sciencemag.org/news/2018/02/boston-university-rejectsgeologist-david-marchant-s-appeal-termination on 7 september 2018. willenbring j. 2018. the elephant in the women-in-science room. speaking of geoscience. accessed online at https:// speakingofgeoscience.org/2018/06/29/the-elephant-in-the -women-in-science-room/ on 7 september 2018. 4 s. starkweather et al. https://doi.org/10.1371/journal.pone.0102172 https://doi.org/10.1371/journal.pone.0102172 https://www.outsideonline.com/2300656/harassment-problem-scientific-dream-jobs?utm_content=bufferf4f3d%26utm_medium=social%26utm_source=twitter%26utm_campaign=tweet https://www.outsideonline.com/2300656/harassment-problem-scientific-dream-jobs?utm_content=bufferf4f3d%26utm_medium=social%26utm_source=twitter%26utm_campaign=tweet https://www.outsideonline.com/2300656/harassment-problem-scientific-dream-jobs?utm_content=bufferf4f3d%26utm_medium=social%26utm_source=twitter%26utm_campaign=tweet https://www.outsideonline.com/2300656/harassment-problem-scientific-dream-jobs?utm_content=bufferf4f3d%26utm_medium=social%26utm_source=twitter%26utm_campaign=tweet https://www.outsideonline.com/2300656/harassment-problem-scientific-dream-jobs?utm_content=bufferf4f3d%26utm_medium=social%26utm_source=twitter%26utm_campaign=tweet https://science.house.gov/legislation/hearings/subcommittee-research-and-technology-hearing-review-sexual-harassment-and https://science.house.gov/legislation/hearings/subcommittee-research-and-technology-hearing-review-sexual-harassment-and https://science.house.gov/legislation/hearings/subcommittee-research-and-technology-hearing-review-sexual-harassment-and https://science.house.gov/legislation/hearings/subcommittee-research-and-technology-hearing-review-sexual-harassment-and http://www.sciencemag.org/news/2018/02/boston-university-rejects-geologist-david-marchant-s-appeal-termination http://www.sciencemag.org/news/2018/02/boston-university-rejects-geologist-david-marchant-s-appeal-termination http://www.sciencemag.org/news/2018/02/boston-university-rejects-geologist-david-marchant-s-appeal-termination https://speakingofgeoscience.org/2018/06/29/the-elephant-in-the-women-in-science-room/ https://speakingofgeoscience.org/2018/06/29/the-elephant-in-the-women-in-science-room/ https://speakingofgeoscience.org/2018/06/29/the-elephant-in-the-women-in-science-room/ abstract background from the event moving forward acknowledgements disclosure statement references photosynthetic responses of selected antarctic plants to solar radiation in the southern maritime antarctic pedro montiel, andrew smith & don keiller the effects of uv-b exclusion and enhancement of solar radiation on photosynthesis of the two phanerogams which occur in the maritime antarctic, deschampsia antarctica and colobanthus quitensis, and the moss sanionia uncinata were investigated. data on air temperature and solar radiation illustrate a drastic seasonal variation. daily o3 column mean values and uv-b measured at ground level document the occurrence of the 0 3 “hole” in the spring of 1997, with a concomitant increase in uv-b. the grass, d. antarctica, exhibited a broad temperature optimum for photosynthesis between 10-25°c while photosynthesis did not saturate even at high irradiance. the high water use efficiencies measured in the grass may be one of the features explaining the presence of this species in the maritime antarctic. the net photosynthesis response to intercellular co2 (nc,) for d. antarctica was typical of a c3 plant. exposure to a biologically effective uv-b irradiance of 0.74 w m-’ did not result in any significant change in either the maximum rate of photosynthesis at saturating coz and light, or in the initial carboxylation efficiency of rubisco. (vc,,,ax). furthermore while ambient (or enhanced) solar uv-b did not affect photochemical yield, measured in the field, of c. quitensis and d. antarctica, uv-b enhancement did affect negatively photochemical yield in s. uncinata. in d. antarctica plants, exposure to uv-b at low irradiances elicited increased flavonoid synthesis. the observed effects of uv-b enhancement on the moss (decreased photochemical yield) and the grass (increase in flavonoids) require further, separate investigation. p. montiel, british antarctic survey, high cross, madingley road, cambridge cb3 oet, uk; a. smith & d. keiller, anglia polytechnic university, east road, cambridge cb1 ipt, uk. summer climatic conditions in the antarctic, together with the isolation from more northerly land-masses, restrict the vegetation in the maritime antarctic to mosses, lichens, algae, cyanobacteria and to two vascular species: the pearlwort colobanthus quitensis and the grass deschampsia anturctica (smith 1984). evidence of climatic change in the antarctic peninsula includes an upward trend in summer air temperatures since the late 1940s (smith 1994). mean annual air temperatures have also increased b y 0.022 to 0.067”c per year (king 1994). since the mid 1970s there has been a marked thinning of the stratospheric ozone layer over the polar regions (farman et al. 1985), which has continued throughout the 1980s and 1990s (jones & shanklin 1995). climate change is likely to lead to shifts in species, communities and relative abundance of polar vegetation (mcgraw & fetcher 1992). without detailed knowledge of species physiology and ecosystem properties, such shifts will be difficult to predict. monitoring populations of both antarctic vas cular species over a 27 year period has revealed a significant increase in numbers of individuals and populations at two separate localities in the maritime antarctic (fowbert & smith 1994). in d. antarctica no specific adaptations to the antarctic environment are evident in terms of reproductive strategies (convey 1996), or the fatty acid composition of phospholipids and galacto lipids in leaves and roots (zuiiiga et al. 1994). however, an inverse relationship of chloroplast to cell area index and temperature has been reported montiel et al. 1999: polar research 18(2), 229-235 229 for d. antarctica along a climatic and latitudinal gradient (jellings et al. 1983). more significantly, one previous study (edwards & smith 1988) suggests that photosynthetic rates in both species approach 30% of their maximum at 0°c. a much larger number of studies on the cryptogamic vegetation of the region exist, including photo synthetic measurements in both lichens (reviewed by schroeter et al. 1997) and mosses (e.g. davey & rothery 1996). cellular responses to extreme fluctuations in solar radiation, temperature and water status are likely to be critical to plant competitive balance (larcher 1995). in antarctic terrestrial biota these relationships remain largely unexplored. the biological effects of uv-b on vegetation can be direct or indirect; direct effects include dna photodamage and physiological effects (reviewed by caldwell et al. 1995). although direct damage of photosystem i1 has been widely documented (bomman 199 1; nedunchezhian & kulandaivelu 1997), inhibition of photosynthesis by uv-b is more likely to be linked to coz fixation (baker et al. 1997). photoprotective responses to uvr include structural modifications and increased synthesis of uv-b absorbing compounds (cald well et al. 1995; rozema et al. 1997). research into the biological effects of increased uv-b in the antarctic has focused mainly on marine ecosystems (see goes et al. 1994; karentz 1994; riegger & robinson 1997; neale et al. 1998), with relatively few studies on photoprotec tive pigments of terrestrial macro-algae, mosses and cyanobacteria (e.g. post 1990; garcia-pichel & castenholz 1991; post & larkum 1993). the present study defined photosynthetic responses in d. anturctica and assessed whether the two vascular plants and the moss sanionia uncinata were responsive to manipulation of the solar environment (chiefly uv-b exclusion and en hancement) under ambient conditions at lconie island. methods monitoring of solar radiation: at rothera station (67"34'07"s, 68"07'30'w), in the south-westem antarctic peninsula, a bentham dm 150 scanning spectroradiometer has measured spectral global irradiance since 1997. measurements are made from 280 to 600 nm with a step size of 0.5 nm and a resolution of 1 nm. the same instrument is used to calibrate uv-a and uv-b sensors (delta-t devices ltd., cambridge, uk) and irradiance (photosynthetically active radiation, par, 400-700 nm) quantum sensors (skye instruments ltd., powys, uk) which are part of a year-round, automated station at lconie island (67"36's, 68"20'w), 9 km south-west of rothera station. field experimentation: all field experimentation was carried out on lconie island. the species selected included the two vascular plants (d. antarctica, c. quitensis) and the moss s. uncinata. these species are found co-existing in similar locations, are widespread along the antarctic peninsula and provide a representative contrast between vascular and cryptogamic life strategies. plants were transplanted to a north-facing terrace, dominated by grass swards. following acclima tion (10 days), plastic screens were positioned to affect changes in solar uv radiation. the screens (du pont polyesters group, middlesborough, uk) used included uv transparent (perspex 0x0-2), uv opaque (perspex ve) and uv-b opaque but uv-a transparent (melinex). uv-b enhancement (around 30% of background solar levels) was provided by a uv-b lamp (3 13 nm maximum, cole-palmer instrument company, london, uk) fitted with sanalux glass panels to absorb uv radiation below 280nm. the uv-b lamp was positioned in such a way so as to provide uniform uv-b enhancement over the test area, whilst not shading any plant material from sunlight. this enhancement (square-wave addition) was given for 5 h day-' around solar noon (13.00 local time). the uv-b lamp (115 vac, 60hz) was switched on only when irradiance exceeded 300 pmoles m-2 s-'. such an arrangement al lowed a total of five contrasting treatments, namely ambient (direct sun), uv transparent, uv exclusion, uv-b exclusion only and uv-b enhancement. controlled environnient experiments: plants (d. antarctica) were collected at signy (60°43's, 45"38w) and lconie islands and transported to the bas headquarters (cambridge, uk) where they were acclimated in growth chambers prior to experiments. chamber temperatures were 15"c/ 7°c for daily 16 h day/8 h night cycles, respec tively. these conditions were used throughout, with plants kept inside growth incubators under modified covers made from the same uv 230 photosynthetic responses of selected antarctic plants to solar radiation 40 ,.. .. ~ ..~. .. ~.-~~-___ ________.. -~ .. g 20 e! lo $ 0 c -20 -10 3 0 ozone -uv-b daily ozone and uv-b mean values rothera 1997/ 9 244 264 284 304 324 344 364 19 39 59 1 (b) sep-97 julian day feb-98 1 lrradiance datale'onie i. 1997/ 98 ~.~ 3000 2500 1 , i (c) 3fflw97 29/9/97 29/10/97 28/11/97 28/12197 27/1/98 26/2/98 28/3/98 f i g . i. seasonal fluctuation in temperature. ozone and solar radiation at kothera station and lconie i., 1997-98. ( a ) air temperatures (20cm above ground) are hourly average of readings taken every 10 min (april 1997-march 199x). (b) ozone column values and uv-b irradiance fluences (derived from scans from the bentham spectrorddiometer) are daily means (september 1997-march 1998). (c) irradiance (photo synthetically active radiation, par) are values ( 10 min intervals) from a quantum sensor (400-700 nm) (september 1997-march 1998). transparent and opaque acrylic plastics as em ployed in the field studies. typical irradiance in the growth cabinets was 150 pmol m-2 si , at plant level, while uv-b and uv-a was main tained at around 0.4 and 5.1 w m-2, respectively, with a daily weighed ("generalized plant action spectrum" by caldwell [197 11; parametrized by t h i m i j a n e t al. [ 1 9 7 8 ] ) dose of 4.89be kj m-' day-' for a 16 h day-' cycle. although the total irradiance in the growth cabinets was low compared to peak irradiance in the field (fig. ic), the ratio of uv-b/uv-apar was similar to that measured in the field, in the absence of significant ozone depletion. it must be noted that in the antarctic the high seasonal variation in irradiance (fig 1; see also davey & rothery 1996) combines with daily variation; high uv-b irradiances can occur at low irra diances during ozone hole events in early spring (webb 1997). photosynthetic gas exchange f o r d. antarctica: a ciras-1 infra-red gas analyser (pp systems ltd., herts., uk) was used, together with a micro processor controlled cuvette which allowed com plete control of leaf micro-environment variables ( c 0 2 , temperature, irradiance and humidity). the ciras1 system allows simultaneous recording of photosynthetic and transpiration rates. only the grass proved suitable for the automated cuvette. water use efficiency (wue) was calculated from c 0 2 and h 2 0 exchange rates (nobel 1991). steady-state photosynthetic rate (measured after 7-8 min. equilibration for temperature and light response curves) was determined at an air flow rate of 300 ml min-', 345 ppm c 0 2 , (unless n c , curves were collected) and 80% relative humidity (5-6 mb). attached d. antarctica leaves were used throughout. temperature response curves (expressed as % of maximum rate achieved per plant, so as to eliminate interplant vari ation caused by different leaf mass), were obtained (10-15 february 1998) from eight plants from three contrasting habitats: full sun (up to 1 8 0 0 p m o l m ~ s ' ) , partial sun (up to 1200 p m o l m 2 s ' ) and shade (up to 250pmol m s-'). irradiance was maintained at 1500 pmol s i while cuvette and leaf temperature was increased stepwise from 2°c to 30 c and decreased similarly from 30°c to 2°c. light response curves were also measured using plants from the same contrasting environments; irradi a n c e w a s i n c r e a s e d s t e p w i s e f r o m 0-1500 pmol m-' s-', following a 15 min dark acclimation, whilst leaf temperature was main tained between 15'c and 20°c. 7 -7 photochemical eficiency: chlorophyll fluores cence was used to monitor psi1 photochemistry in undisturbed plants exposed to the different uv treatments. measurements were made in the morning and again towards the end of the day period in order to evaluate any possible interac tion between uv treatments and extended ex posure to high irradiance. a portable osloo modulated chlorophyll fluorometer (opti sciences inc, ma, usa) was used to obtain montiel et al. 1999: polur research 18(2), 229-235 23 1 u) .g loo qm 240 q 5 8 0 ~ . b c t 0 steady-state yield values from undisturbed plants under field conditions. the fluorometer was used with a modified, 65” open-body cuvette guide and an irradiance (par) sensor. transplanted plants were “tagged” so that positioning of the fluorom eter fiber optic tip on the same spots (4-5 per treatment) was reproducible throughout the ex periments. relative amplitude of the modulated light was set at 60 (vascular plants) and 70 (the moss) with a 0.8 s pulse duration. # x x e n p ’5 3 $2 g $ 6 w b 10 5 a.0. : =i# 4 e g % !b r 10 n c w b l € 9: 2o 0 ) x a x = x ~~ > (n a j+ r i r m y ~~ c ‘ e ‘ l t x t 5 w total flavonoid analysis by hplc: gradient hplc analysis of flavonoids was performed on a prodigy ods3 column (phenomenex, cheshire, uk), at 30°c with diode array detection. plant tissue was ground in a pestle and mortar with cold 50% aqueous methanol containing 0.5% (v/v) 400 800 1200 1 -5 lrradiance (~idi / n?/ s) f i g 3. light response curves for d. aritarctica plants from contrasting habitats (open circles = full sun-exposed; filled circles = shade). irradiance was increased stepwise from 0-1500 pmol m-2 sc1 (dark acclimation for 15 min). leaf (and cuvette) temperature were kept between 15°c and 20°c. glacial acetic acid, after which the extracts were centrifuged and passed through 0.45 pm filters. mobile phases included ammonium dihydrogen phosphate (ph 2.5) and absolute acetonitrile (lunte 1987). results data on air temperature (20 cm above ground) and solar radiation illustrate a drastic seasonal varia tion (figs. la, c). daily 0 3 column mean values and uv-b (averaged from the bentham scans) illustrate the occurrence of the o3 “hole” in the spring of 1997, with a concomitant increase in uv-b during november 1997 (fig. lb). photosynthesis measurements showed that d. antarctica had a broad temperature optimum (approximately 90% of the maximum) between 10-25°c (fig. 2). photosynthetic rate response to irradiance revealed no saturation at high irradiance even in plants from shaded environments. similarly there was very little difference in light compensation points between plants collected from the contrast ing habitats (fig. 3). apparent water use efficiency (wue) was very high, with values ranging between 62 and 123 mol h 2 0 per mol coz; typical values for c3 species are between 300-500mol h 2 0 per mol. such effi ciency, if confirmed in the natural environment, may partially explain the capacity of this species to 232 photosynthetic responses of selected antarctic plants to solar radiation j 0.600 e -f i 0.m d 0.2w 0 000 fig. 5 . steady-state yield fluorescence parameter determined in the natural environment for (a) c. quitensis, (b) d. rmrc~rc.ticn and (c) s. uricinnfa, following 7 days exposure to ambient conditions. lotal uv radiation exclusion, selective uv-b exclusion and ljv-b enhancement (7-8 february 1998). means & 1 se are given. measurements were carried out in the morning (10.00 h, filled bars) and evening (19.30 h, open bars). statistical significance (r-test, one-tail) is indicated (+ p < 0.5) for the comparison of treatments vs ambient control. survive in the cold semi-desert conditions of the maritime antarctic (fig. 4). chlorophyll fluorescence is used routinely as an intrinsic probe of photosynthetic function and as a screening tool for environmental stress tolerance, e.g. low temperatures (oquist & huner 1993), dehydration (casper et al. 1993), and uv-b (vassiliev et al. 1994). for both phanerogams the data suggest that following an initial transient reduction in psii yield, induced by uv-b enhancement (data not shown), there was no significant change in psii efficiency (figs. 5a. b). in contrast, a significant and sustained decrease in photochemical yield was recorded for the moss s. uncinata when exposed to enhanced uv-b (fig. 5c). i i 5 " " " "" " ' " " " " ' " ' ' 4 0 m 4 m ) 6 0 0 8 0 0 1 w o internal co, (ci, ppn) fig. 6. a/ci response curves (net photosynthesis response to intercellular co? concentration) for d. antarcticn plants, maintained in controlled environment cabinets. and acclimated to uv-b exclusion or exposure (biologically effective irra diance of 0.74 w m-* uv-b). steady-state photosynthesis (measured after 7-8 min equilibration) was determined at an air flow rate of 300 ml m i n ~ ' , 345 pl1-i coz, and 80% relative humidity (5-6 mb). attached d. antarcticn leaves were used throughout. uv-b enhancement had little or no effect on the net assimilation response to intercellular c 0 2 concentration (a/ci) in d. antarctica (fig. 6). hplc analysis of d. antarctica shoots kept in controlled environments at low irradiances showed that total flavonoid were increased by exposure to uv-b, with some flavonoid species showing marked increases (peaks 1, 2, 3 and 7 in the overlay chromatograms; fig. 7). the identity of these flavonoids requires further investigation. discussion d. antarctica exhibited a typical c3-type response to temperature with a broad optimum. optimal temperatures for net co2 uptake are usually between 20°c to 35°c for c3 plants (nobel 1991); thus the lower optimum for d. anturctica could be regarded as a specific adaptation. a wide optimum has the advantage that large daily fluctuations in temperature result in only small changes in photosynthetic rate (larcher 1995). the data also confirmed that d. antarctica can sustain net photosynthesis (15-25% of maximum rate) at temperatures approaching 0°c (edwards & smith 1988). the response of net photosynthesis to irradiance indicate that light saturation did not occur at high irradiance even when using plants montiel et al. 1999: polar research 18(2). 229-235 233 -25 ! i i i i i i i 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 time (rnin) fig. 7. desclznmnpsifi antnrcfica. overlay of chromatograms from two flavonoid extracts from tillers grown under conditions of low irradiances and where uv-b was excluded (-uv-b) or allowed through (+uv-b) for 17 days. plants were grown at 1s0c/7'c for 1 6 h day/8h dark daily cycles. extracts were prepared using similar amounts of leaf material (around 20 mg fresh weight) and injection of 60p1 from equal dilution volumes from shade habitats. a high saturation point may allow fuller exploitation of the high irradiance levels experienced in the region during the growing season (fig. lc), and may also serve as a protective mechanism against photoinhibition (long & humpries 1994). the gas exchange data, alci response curves in particular (figs. 2, 6), confirm that d. anfarctica uses c3-type photosynthesis (sage 1994). how ever instantaneous water use efficiency (wue) values were markedly higher than expected for a c3 grass. comparable wue values have been reported in both c3 and cam succulents, from the southern namib desert, suggesting that some c3 plants can achieve high wue values (eller & ferrari 1997). it is hypothesized that the high wue of the hair-grass may play an important role in the successful performance of the plant in an environment where free water is restricted. the finding that uv-b exposure did not effect psii photochemical yield in either vascular species (fig. sa and fig. sb) concurs with the emerging consensus that psii damage is only manifested at high and unrealistic uv-b exposures (allen, mckee et al. 1997; allen, nogucs et al. 1998). similarly, exposure to a biologically effective uv b irradiance of 0.74 w m-' (caldwell-weighted), at a relatively low irradiance in growth cabinets, did not result in any significant change in either the maximum rate of photosynthesis at saturating c 0 2 and light (j,,,), or in v,,,,,. in contrast, baker et al. (1997) reported significant reductions in both these parameters at uv-b irradiances of 0.63 w mp2. the responses of the vascular plants, in terms of photosynthesis and photoprotective pigments, to exclusiodenhancement of solar uv b, indicates that current uv-b levels, experienced by c. quitensis and d. antaictica during the growing season, may not constitute a direct threat to photosynthetic activity. furthermore, because of snow cover these species are unlikely to experience the elevated uv-b levels occurring during the spring o3 depletion event (fig. lc). the negative effect of uv-b enhancement on photo chemical yield in the green moss s. uncinata requires further evaluation (fig. 5c). this study has shown that exposure to enhanced solar uv-b irradiance elicited increased flavonoid production in d. antarctica (fig. 7), thus seques tering energetic resources. vegetation of the maritime antarctic are slow growing, and sub jected to numerous abiotic stresses, thus photo assimilate allocation may prove critical to survival. in antarctic ecosystems particular atten tion should be paid to indirect plant responses to enhanced solar uv-b radiation; these are likely to affect competitive balance in species at the limits of their survival, with possible implications to biodiversity within ecosystems (caldwell et al. 1995). it has been suggested that the current trend towards warmer growing seasons in the region will result in increased colonization by vascular plants (fowbert & smith 1994). the results of this study support this hypothesis, as photosynthesis in these species appears to be well-adapted to current levels of solar irradiance and uv radiation. acknowledgements. the authors wish to thank dr. helen peat and andrew rossaak for processing micro-meteorological data, dr. brian gardiner for providing the ozone column data and to rothera station personnel (a. rossaak and p. wickens in particular) for the logistical support that made the field work possible and enjoyable. the melinex plastic used was a gift from the du pont polyester group (wilton, middlesborough. u k l references allen, d. j., mckee, i. f., farage, p. k . & baker, n. r. 1997: analysis of the limitation to coz assimilation on exposure of leaves of two brussicn napus cultivars to uv-b. plant, cell eizviron. 20, 633-640. allen, d. j., nogubs, s. & baker, n. r. 1998: ozone depletion and increased uv-b radiation: is there a real threat to photosynthesis? .i. exp. bot. 49. 1775-1788. 234 photosynthetic responses of selected antarctic plants to solar radiation baker, n. r., noguts, s. & allen, d. j. 1997: photosynthesis and photoinhihition. in p. j. lumsden (ed): plants and uv-b: responses to environmental change. seb series 64. pp. 85-1 11. cambridge: cambridge university press. bornman, j . f. 1991: uv radiation as an environmental stress in plants. j . photochem. photobiol. b: biol. 8, 337-342. caldwell, m. m. 1971: solar ultraviolet radiation and the growth and development of higher plants. in a. c. giese (ed.): photophysiology. vol. 6. pp. 131-177. new york: academic press. caldwell, m. m., teramura, a. h., tevini, m., bornman. j . f., bjorn, l. 0. & kulandaivelu, g. 1995: effects of increased solar ultraviolet radiation on terrestrial plants. ambio 24, 166-173. casper, c., eickmeier, w. & osmond, c. b. 1993: changes in fluorescence and xanthophyll pigments during dehydration in the resurrection plant selaniellu lepidophylla in low and medium light intensities. oecologia 94, 528-533. convey, p. 1996: reproduction of antarctic flowering plants. antarct. sci. 8, 127-134. davey, m. c. & rothery, p. 1996: seasonal variation in respiratory and photosynthetic parameters in three mosses from the maritime antarctic. ann. bot. 78, 719-728. edwards, j . a. & smith, r. 1. l. 1988: photosynthesis and respiration of colobanthus quitensis and deschampsia antarctica from the maritime antarctic. br. antarct. sum. bull. 81, 43-63. eller, b. m. & feaari, s. 1997: water use efficiency of two succulents with contrasting c02 fixation pathways. plant, cell environ. 20, 93-100. farman, j. c., gardiner, b . g. & sbanklin, j. d. 1985: large losses of total ozone in antarctica reveal seasonal clox/no interaction. nature 315, 207-210. fowbert, j. a. & smith, r. i. l. 1994: rapid population increases in native vascular plants in the argentine islands, antarctic peninsula. arct. alp. rex 26, 29cl-296. garcia-picbel, f. & castenholz, r. w. 1991: characterization and biological implications of scytonemin, a cyanobacterial sheath pigment. j . phycol. 27, 3 9 5 4 0 9 . goes, j. i., handa, n., taguchi, s. & hama, t. 1994: effect of uv-b radiation on the fatty acid composition of the marine phytoplankter tetraselmis sp.: relationship to cellular pig ments. mar. ecol. prog. ser. 114, 259-274. jellings, a. j., usher, m. b. & leech, r. m. 1983: variation in the chloroplast to cell area index in deschampsia antarctica along a 16" latitudinal gradient. br. antarct. sun>. buil. 6 1 , 3-20. jones, a. e. & shanklin, j. d. 1995. continued decline of' total ozone over halley, antarctica, since 1985. nature 376, 4 0 9 4 1 1. karentz, d. 1994: ultraviolet tolerance mechanisms in antarc tic marine organisms. in c. s. weiler & p. a. penhale (eds): ultraviolet radiation in antarctica: measurements and biological effects. antarct. res. ser. 62, 93-1 10. king, j. c. 1994: recent climate variability in the vicinity of the antarctic peninsula. int. j . climatol. 14, 357-369. larcher, w. 1995: gas exchange in plants. in w. larcher: physiological plant ecology. 3rd edition. pp. 74-128. berlin: springer. long, s. p. & humpries, s. 1994: photoinhibition of photo synthesis in nature. ann. rev. plant physiol. plant m o l . b i d . 45, 663-662. lunte, s. m. 1987: structural identification of flavonoids in beverages by liquid chromatography with ultraviolet-visible and electrochemical detection. j. chromatogr. 384,371-382. mcgraw, j. b. & fetcher, n. 1992: response of tundra plant populations to climatic change. in f. s. chapin et al. (eds.): arctic ecosystems in a changing climate: an ecophysiological perspective. pp. 359-376. san diego: academic press. neale, p. j., davis, r. f. & cullen j. j. 1998: interactive effects of ozone depletion and vertical mixing on photosynthesis of antarctic phytoplankton. nature 392, 585-589. nedunchezcian, n. & kulandaivelu, g. 1997: changes induced by ultraviolet (280-320 nm) radiation to vegetative growth and photosynthetic characteristics in field grown vigna unguiculata. plant sci. 123, 85-92. nobel, p. s. 1991: physicochemical and environmental plant physiology. new york academic press. 635 pp. oquist, g. & huner, n. p. a. 1993: cold-hardening induced resistance to photoinhihition of photosynthesis in winter rye is dependent upon an increased capacity for photosynthesis. planta 189, 150-156. post, a. 1990. photoprotective pigment as an adaptive strategy in the antarctic moss ceratodon purpureus. polar biol. 10, 24 1-245. post, a. & larkum, a. w. d. 1993: uv-absorbing pigments, photosynthesis and uv exposure in antarctica: comparison of terrestrial and marine algae. aquat. bot. 45, 231-243. riegger, l. & robinson, d. 1997: photoinduction of uv absorbing compounds in antarctic diatoms and phaecystis antarctica. mar. ecol. prog. ser. 160, 13-25. rozema, j., van de staaij, j., bjorn, l. 0. & caldwell, m . m. 1997: uv-b as an environmental factor in plant life: stress and regulation. trends ecol. evol. 12, 22-28. sage, r . f. 1994: acclimation of photosynthesis to increasing atmospheric coz: the gas exchange perspective. photosyn. scbroeter, b., kappen, l., green, t. g. a. & seppelt, r. d. 1997: lichens and the antarctic environment: effects of temperature and water availability on photosynthesis. in w. b. lyons et al. (eds): ecosystem processes in antarctic ice free land.scapes. pp. 103-1 17. rotterdam: balkema. smith, r. i. l. 1984: terrestrial plant biology of the sub antarctic and antarctic. in r. m. laws (ed.): antarctic ecology. vol. 1. pp. 61-162. london: academic press. smith, r. i. l. 1994: vascular plants as bioindicators of regional warming in antarctica. oecologia 99, 322-328. thimijan, r. w., carns, h. r. & campbell, l. e. 1978: final report (epa-iag-d6-0168): radiation sources and relative environmental control f o r biological and climatic effects of uv research (bacer). washington, d.c.: environmental protection agency. vassiliev, i. r., prasil, o., wynam k. d., kolber z., hanson, a. k. jr., prentice, j. e. & falkowski, p. g. 1994. inhibition of psi1 photochemistry by irradiance and uv radiation in natural phytoplankton communities. photosyn. res. 42, 51-64. webb, a. r. 1997. monitoring changes in uv-b radiation. in p. j. lumsden (ed.): plants and uv-b: responses to environ mental change. pp. 13-30. cambridge: cambridge university press. zufiiga, g. e., alberdi, m., fernandez, j., moutiel, p. & corcuera, l. j. 1994: lipid content in leaves of deschampsia antarctica from the maritime antarctic. phytochemistry 37, 669-672. res. 39, 3.5-368. montiel et al. 1999: p o l a r research 18(2), 229-235 235 222rn and 226ra: indicators of sea-ice effects on air-sea gas exchange kent a . fanning and linda m. torres fanning. k. a . & torres. l. m. 1991: i2'rn and ""ra: indicators of sea-ice effects on air-sea gas exchange. pp. 51-58 in sakshaug. e . , hopkins. c. c. e . & oritsland. n . a . (eds.): proceedings of the pro mare symposium on polar marine ecology, trondhcim. 12-16 may 1990. polar research 10(1). i2'rn and 226ra distributions beneath the sea ice of the barents sea revealed that ice cover has varied effects on air-sea gas exchange. twice, once in late summer and once in late winter, seawater samples from the top meter below drill holes had zzrrn activities that were not lower than their '"ra activities. indicating the existence of secular equilibrium and a negligible net exchange of lr2rn and other gases with the atmosphere. however. seawater in the upper 20-85 m usually exhibited at least somc zzrrn depletion; 22'rn-to-2'bra activity ratios tended to have 'ice-free' values (0.3-0.9) in the summer and values between 0.9 and 1.0 in the winter. integrated '*'rn depletions and piston velocities in both seasons typically fell in the lower 25% of the ranges for ice-free seawater. suggesting that a moderate but far from total reduction in gas exchange is normally caused by ice cover and/or meltwater. the results demonstrate that sea-ice interference with the oceanic uptake of atmospheric gases such as coz is not well understood and needs further investigation. kent a . fanning and linda m. torres, department of marine science, uniuersit.v of south florida, sf. petersburg, florida 33701, usa introduction the global significance of the effects of sea-ice cover on air-gas exchange is unresolved at present. a complete absence of atmospheric-c02 penetration through sea ice of the weddell sea was invoked to help explain why sinking antarctic bottom water appears t o carry away only 15% of the anthropogenic excess c 0 2 that enters the surface ocean (poisson & chen 1987). a partial rather than a complete reduction of gas exchange across sea ice was implied by water-mass studies that found freons f-11 and f-12 to be 20-37% undersaturated in the surface arctic ocean (kry sell & wallace 1988; wallace et al. 1987). these studies emphasized the consequences of high latitude gas exchange on oceanic solutes but they did not determine gas-exchange parameters for the air-seawater (or air-ice-seawater) interface. 222rn is a quantitative tracer of air-sea gas exchange on time scales of a few days (broecker & peng 1971, 1974, 1982; peng et al. 1979; sme thie et al. 1985; glover & reeburgh 1987). in a parcel of seawater isolated from exchange with the atmosphere or underlying sediments, activi ties of 222rn (a222) and its parent 226ra (a?2h) will become equal and attain a condition called secular equilibrium. near the sea surface in the ocean's mixed layer, secular equilibrium is dis rupted by the preferential escape of radon to the atmosphere, and the ratio of a222 to is thus <1.0. a222:a226 ratios in ice-free oceanic mixed layers are typically 0.5-0.9, averaging 0.76 (50.09) in geosecs studies (peng et al. 1979) and 0.75 (50.07) in transient tracers' studies (smethie et al. 1985). the lowest observed ratios are -0.3 in the bering sea (glover & reeburgh 1987). piston uelocify, which is defined as the thickness of a sea water column exchanging gas with the atmosphere per unit time (broecker & peng 1982), ranges over nearly two orders of magnitude in ice-free seawater (table 1). the work reported here was a reconnaisance of 222rn and 226ra distributions near sea ice. our objectives were to obtain new insights into the mechanisms of air-sea gas exchange in ice-bearing waters and to estimate the 222rn depletions and piston velocities in the presence of sea ice for comparison to values for the same exchange par ameters in the absence of sea ice. materials and methods the work was done in april 1986 (late winter), and september 1988 (late summer), aboard the norwegian coast guard icebreaker k/v andenes during the norwegian pro mare program on the 5 2 k . a . fanning & l . ,m. torres table 1 comparison ot w i t h 2z2rn gas exchange parameters elsewhere in the ocean :rn gas exchange parameters in the barents s c j i n late winter (april) and late summer (september) barents sea elsewhere late winter late summer whole tropical bcring hydrostaiions ice station5 ocean atlantic sea (ref 1 ) (ref 2) (ref. 3 ) 43 52 7 3 depth of !'?rn depletion ( m ) total ?'!rn depletion (dpm m ') value( s ) average piston velocity (m d i ) value( s) average piston velocity (20°c) value(s) average 110 63 10-20 15-20 48 ( 2 2 6 ) 280 610 3jo-680 3jo-450 190-3610 330-2190 960 1239 0.6 1 . 5 1.3-2.6 0 9-1.2 0.5-12.7 1.4-6.9 0.2-4.9 2 8 3.6 2.2 1 . 2 2.8 2.5-5.1 1 9 2 . 4 0.6-18.6 1.1-6.0 3 3 3 . 1 references: ( i ) peng et al (1979) (2) smcthic et al (1985). ( 3 ) glover & reeburgh (1987) barents sea. this scheduling permitted a range of sea-ice effects to be examined because of the large seasonal variations in barents sea ice cover. the winter cruise (fig. 1 ) investigated the entire water column beneath or adjacent to close packed winter ice (>90% surface coverage). sea 10" 20" 30" 40' 50"e 1 " " " " ' " " " ' " ' 1 8 0 " n c x ice slation a2 * ?v 'ice sialion a 3 x ice stailon l5 m t 1 @ = winter slalions (19061 i f i r i . map of the barents sea showing the station locations during the late -,inter cruise of april 1986. and the late summcr cruise of september 1988. approximate ice limits are also s h o s n . water i n natural or ship-created open areas was sampled with 30-liter niskin bottles to within 10 m of the bottom. hydrographic parameters were determined with a ctd or discrete sampling. at an ice station ( h l ) , a helicopter served as transport for collecting seawater below unbroken ice more than 50 miles from the vessel. a small ( 10 cm) hole was drilled into the ice, and vacua in gas-tight, 20-liter pvc sampling bottles were used to suck seawater from beneath the ice through weighted tubing (i.d.: 6-12 mm) (fig. the late summer cruise (fig. 1) consisted entirely of ice stations at which the 1986 ice station protocol was followed (fig. 2). surface ice coverage within the pack was ~ 7 0 % . 2zzrn activities were determined aboard the vessel after using the 20-liter pvc bottles as z22rn-extraction chambers (mathieu et al. 1988) (fig. 2 ) . overall 222rn extraction and counting efficiency was 85%. after the extractions, the seawater samples were slowly passed through col umns of mn-oxide-coated acrylic fiber to extract 22hra (reid et al. 1979). later. the columns were sealed in gas-washing bottles so that the 226ra activities of the original samples could be deter mined from the z22rn ingrown after >lmonth of storage i n accordance with the tests and rec ommendations of moore (1981). relative stand ard deviations of replicate 226ra analyses averaged 6%. 2 ) . indicators of sea-ice effects 53 sight tubf 1 a e v a +=? hole drilled with auger -1, top of ice weighted sample tube di1 inlet valve gas dispersion frlt to outlet valve i 'bottom of ice inlet valve arrows show path of helium d c fig. 2. diagram of the deployment and use of 20-liter pvc radon sampling and extraction bottles showing: a ) an overall view. b) a cutaway view. c) a bottle in sampling position for sucking seawater through weighted tubing lowered into drill holes at ice stations. and d) a radon extraction. vacua in the bottles were also used to suck seawater from 30-liter niskin bottles at pro marc hydrostations. face water. out of sixteen samplings of the upper 85 m, ten had a222:a226 values higher than the normal range (0.5-0.9), and six had ratios within it. five of those (two each at hydrostations 43 and 52 and one at ice station h1) exceeded 0.8. these results suggest that the extensive ice cover retarded the degree of degassing. one sample in results the late winter cruise of 1986 upper portions of the winter z2zrn and 226ra profiles (fig. 3) approached secular equilibrium much more closely than reported for ice-free sur v i l 3 ? 2. i? a c t iv it y ( g ) 3 0 1 0 1 0 0 2 0 0 30 0 4 0 0 e n n v i iw a > 1 ' t r a l * 5 i ? < i : v ) i 1 i l l 1 a c t iv it y ( g ) 0 1 0 2 0 3 0 2 0 0 30 0 r a i i 0 4 0 0 0 1 0 2 0 3 0 4 0 s a l in it y ( % o ) s ta ti o n 4 3 s h ip -m a d e o p e n in g in t h in i c e 1 0 2 0 3 0 4 0 s a l in it y ( % o ) s ta ti o n 5 2 s ta ti o n 3 7 o p e n w a te r n e a r i c e e d g e o p e n w a te r w it h in i c e , c e n t r a l b a n k 1 0 2 0 3 0 4 0 s a l in it y ( '3 0 0 ) ic e s ta . h 1 f ir . 3 pr of ile s of ' "r n ac tiv ity a nd " 'r a ac tiv ity a nd s al in it y fo r th c b ar cn ts s ea c ru is c in l ar e w in te r. a pr il 1 98 6 (h yd ro st at io ns 4 3. 5 2 an d 37 a nd i cc s ta ti on h i) . d cp th s w er e m ea su rc d w ith r cf er cn cc t o th e se a su rf ac c at h yd ro st at io ns o r to t he i ce s ur fa ce a t ic e rt at io ns . s ca w at cr r os e to w ith in 5 c m o f th c ic e su rf ac c in a ll d ri ll ho le s. c t d s al in ity p ro fi le s ar e sh ow n as s ol id l in cs w it ho ut d at a po in ts : di sc re te s al in it y m ca w re m en ts a re i nd ic at ed b y so lid c ir cl es ( 0 ) . indicators of sea-ice effects 5 5 0 10 the upper 20 meters (the 1-m sample at ice station h1) showed clear evidence for secular equilib rium, i.e. no reduction in below another 1-meter sample (at hydrostation 43) had an a z 2 ? value 4% below its a,,, value. this sample was close t o secular equilibrium, but could also have experienced a small amount of recent exchange. to o u r knowledge, the water column at hydrostation 43 comes the closest to exhibiting no **'rn loss to t h e atmosphere of all oceanic water columns studied to date. its lowest a 2 2 2 : a 2 2 6 value was 0.93 at 1 0 m ; all others in the upper 100 m fell between that value and 1.0. the strongest winter 222rn depletions were a t hydrostation 37 which had also apparently under gone a recent water-column turnover. a layer in the upper 20 m with a 40-70% 222rn surplus was both overlain and underlain by seawater with -20% z22rn depletion. large near-bottom '"rn enrichments at hydrostations 43 and 52 and the small near-bottom enrichment at hydrostation 37 indicated that barents sea sediments, as bering sea sediments (glover & reeburgh 1987) and other shelf sediments (fanning et al. 1982), emit 222rn and label near-bottom water with an a222 value greater than its a226 value. thus the 222rn surplus in the seawater at 7-15111 denotes its recent near-bottom origin, and the 222rn deple tion between 40 and 7 8 m denotes the recent arrival of air-exposed surface water. the water column had little density structure to provide stability, being isohaline (34.5%0 salinity) and almost isothermal (-1.7 t o -13°c). in addition the water was much shallower than at the other hydrostations (135 m vs. 300-400 m), and the sea surface was ice-free. these three conditions prob ably led to t h e overturn and the increased out gassing relative t o t h e other hydrostations. depths of the 222rn-deficient zones beneath the late-winter ice were taken as the depths at which secular equilibrium appeared or were esti mated by linear interpolation between the great est depth showing a 222rn depletion and the next *. % : i d i \ + /!la-226 4 ) : i . i ! i i l salinity : i & 0 fig. 4. profiles of 222rn activity and **"ra activity and salinity for the barents sea cruise in late summer. september 1988 (ice stations 2 and 3). depths were measured with reference to the sea surface at hydrostations or to the ice surface at ice stations. seawater rosc to within 5 em of the ice surface in all drill holes. discretc salinity measurements are indicated hy solid circles (0). ice sta. 2 10 20 30 0 10 20 30 salinity (%o) ice sta. 3 10 20 30 1 rn-222 i 2o 0 10 20 30 salinity (%o) 56 k . a. funrirng c(: l . m . torres depth sampled (table 1 ) . the zones extended deeper (60-110 m ) than usually observed (peng et al. 1979) and reached the depletion depths found after storms (fanning et al. 1982). salinities at hydrostations 43 and 52 had slight increases from -34.ytr above 5 0 m to -35.1% below 100 m . however the density increases that might have resulted were partially offset by temperature increases from 1 to 2°c above 50 m to 1 .o"c below 100rn. resulting in a weak water-column stability that allowed deeper penetration of gas exchange processes. t h e largest pycnocline that was found occurred between 100 and 120m at hydrostation 43 where u, increased by only 0.12. by contrast, ut changes over 20-meter-thick pycnoclines in the bering sea were -8 times larger (fig. 3d in glover & reeburgh 1987). beneath ice station 3 (fig. 4). showed no reduction of a,?? below a?,,. since the water was obviously meltwater (salinity = 6.1%), a reasonable explanation is that i t was confined to the upper portion of an ice-walled cavity. other wise. the mixing processes that were producing and distributing strongly '??rn-deficient waters throughout the region should have destroyed the strong halocline between 1 and 2 m along with the associated secular equilibrium. apparently. the combination of solid ice walls and meltwater was capable of restricting '"rn loss enough to maintain secular equilibrium despite the sub stantial air-sea "'rn exchange indicated by the normal-to-extensive '??rn depletions in the top meter beneath ice stations 2 and 5. the late sunirner cricise of i988 discussion profiles for this cruise indicated much greater individual '"rn depletions (fig. 4). most of the ---rn-'2hra data pairs from ice stations 2 and 3 had activity ratios i n the normal range: 0.5-0.9. two had very low ratios of 0.30 and 0.37 ( t h e 2-m and 3-m values, respectively. from ice station 2) not shown is a 1-meter sample taken at ice station 5 (see fig. 1) with = 2 . 8 d p m (loool)-'. = 0.38. these low values confirm previous bering sea findings that water parcels at high-latitude can undergo considerable ?:?rn loss during the sum mer (glover & reeburgh 1987). the summertime "'rn losses occurred in ice melt-stabilized seawater. north of 79" n in the region containing the three ice stations (fig. 1 ) . pro mare c t d casts detected a surface layer in which temperatures were usually less than -1.4"c. and salinities ranged from 3 3 . 0 % ~ to less than 1 w c r (fig. 4 ) . t h e layer was 2 0 m thick at most locations. clearly identifiable thermoclines and haloclines and strong pycnoclines lay between the layer and deeper waters having temperatures between 1 and 0°c and salinities >34cr. t h e greater openness of the summer ice pack (s70qr coverage) and steady winds from the northwest quadrant at 3-10 m s ' apparently enhanced the degassing in the open areas and the downward and horizontal mixing of the ??'rn-deficient waters in the meltwater layer one example of under-ice secular equilibrium was found during the summer cruise. as at the wintertime ice station h 1 in fig. 3. 1-meter water 77 = 7.4 dpm (100 l ) ' . and a ? ? ? : ,,, ---rn depletions and piston velocities for both summer and winter were calculated by integrating depth profiles (smethie e t al. 1985) for all stations in figs. 3 and 4 except hydrostation 37 which, due to turnover. was obviously not at steady state. comparisons were then made to parameters either published in or calculated from previous studies (table 1). for hydrostations 43 and 52, integrations were made between the surface and the estimated depths of depletion (see above). time and equipment constraints prevented a more detailed sampling of the water column, resulting in fairly large uncertainties i n the measured thicknesses of the z'rrn depletion zones at hydrostations 43 and 52. t h e consequent errors in the depletions and piston velocities for those stations in table 1 are estimated t o be up to 18% for hydrostations 43 and 30% for hydrostation 52. these values fall in the ranges reported by smethie e t al. (1985). because the difficulty of sampling through drill holes precluded the precise determination of depletion depths during the summer cruise, the maximum summertime depletion depth was assumed to be the maximum thickness of the meltwater layer (20 m ) . this assumption was employed because pycnoclines at the base of the meltwater were 20-40 times the largest 1986 win ter pycnocline and 2-5 times the bering sea pycnoclines found by glover & reeburgh (1987). thus. parameters for ice stations 2 and 3 in table 1 are shown with ranges. low values are based on the average depletions down t o the greatest indicators of sea-ice effects 57 regions o n the underside of the ice. t h e ice struc tures that produce the isolation are unknown. normally, even in winter, breaks or other weak nesses in the ice cover seem to be present in sufficient abundance that the integrated gas exchange over the surface water column is slightly less than observed in ice-free seawater. the impli cation for the possible role of seawater as a sink for anthropogenic coz is that sea ice is a 'porous' barrier t o the uptake of c 0 2 by high-latitude surface waters having a p c 0 2 below the atmospheric value. poisson & chen's (1987) assumption of n o gas exchange across weddell sea ice during the formation of antarctic bottom water is thus open to question, although the lack of an appreciable p c 0 2 gradient across weddell sea ice may mean that an impermeable ice barrier is not required t o explain the low amounts of anthropogenic coz in antarctic bottom water. until direct studies of '"rn beneath weddell sea ice are performed in winter, the uncertainty regarding the influence of antarctic sea ice on the fate of atmospheric coz will remain. ackriowledgemenrs. pro mare provided logistical support. financial support was provided by the univcrsity of south florida faculty rcsearch and creative scholarship fund. the american-scandinavian foundation. the u . s . national science foundation (via grant int 8900496 to scripps institution o f oceanography and grant oce wi33y2 to the university of south florida), and pro mare. c. rooth supplied valuable comments and suggestions. depth sampled, and high values on the assumption that those depletions persisted t o 20 meters. barents-sea l z 2 r n depletions and piston vel ocities fit within the ranges of those parameters found elsewhere in ice-free seawater. t h e overall range of barents sea z22rn depletions (280 680 dpm m-i) falls in the lower 14% of the whole ocean range and the lower 19% of the tropical atlantic range. t h e overall range of barents sea piston velocities normalized to 20°c (1.2-5.1 m d & ' ) falls in the lower 25% of the whole-ocean range, but the highest normalized barents sea piston velocity is only 15% below the highest tropical-atlantic value. although these com parisons clearly indicate that sea ice restricts gas exchange, barents sea parameters are far from the zeros t o be expected if sea-ice cover routinely permitted no gas exchange. as required by the antarctic excess-coz model of poisson & chen (1987). our zz2rn and 226ra results a r e much more consistent with the weaker restrictions on gas-exchange implied by the moderate freon undersaturations in the arctic ocean (krysell & wallace 1988; wallace e t al. 1987). even a t ice covered hydrostation 43, the upper third of the water column had a 2 2 2 : a z 2 6 ratios that were uniformly, albeit just slightly, less than unity. interestingly, integrated barents sea '"rn depletions and piston velocities varied little between summer and winter, suggesting that the overall effect of sea ice o n air-sea gas exchange is roughly the same in both seasons (table 1). in summer, individual percent depletions were high, but ice meltwater was present to constrain the depth of exchange. in winter, low water-column stability permitted the deeper penetration of 222rn outgassing t o 60-110 m, but the greater ice cover appeared t o restrict the degrees of deple tion. probably there was a deep convection fol lowed by a horizontal advection of ??'rn-depleted water associated with the leads that occupy at least 1% of a sea-ice region, even in winter (smith et al. 1990). the distributions of 222rn depletions and enrichments at hydrostation 37 (fig. 3) sug gest that the process in those leads might begin with the turnover of a low-stability water column. conclusion from measurements using a 222rn tracer, our conclusion is that strong retardation of air-sea gas exchange by sea ice occurs mainly in isolated references broecker. w . s . & peng. ts.-h. 1y71: the vertical distribution of radon in the bomex area. earth planer. sci. l e n . 1 1 , 9 9108. broecker, w . s . & pcng. ts.-h. 1974: gas exchange rates between air and sea. tellur 26. 21-35. broecker, w . s . & peng. ts.-h. 1982: tracers in the sea. eldigio press, palisades. n . y fanning, k . a , , brcland. j . a , . 11. & byrne, r. h. 1y82: radium-226 and radon-222 in the coastal waters of west florida: concentration and atmospheric degassing. science 215. 667-670. glover. d. m. & reeburgh. w . s . 1987: radon-222 and radium 226 in southeastern bering sea shelf waters and bediment. conr. sherf res. 7. 433-456. krysell. m. & wallace. d. w . r 1988: arcticocean ventilation studies w i t h a suite of anthropogcnic halocarhon tracers. science, 242. 746749. mathieu. g. g.. biscaye. p. e . . lupton. r. a . & hammond. d. e. iy8x: measurement of radon-222 in natural watcr systems. healrli pltys 55. 989-y92. moore. w. s . iyxi: radium isotopes in the chesapeake bay. esruar. cousr. shelf scr. 1 2 . 713-723. peng, t 5 . h . , broecker. w . s . . mathicu. g. g . & li. y.-€1. 58 k. a. fanning & l . m . torres 1979: radon evasion rates in the atlantic and pacific ocean5 as determined during the gcosecs program. j . geophvs. res. 84. 2471-2486 poisson. a . & chcn. c:t. 1987. why is there littlc anthro pogcnic co: in the antarctic bottom watcr? deep-sea res 34. 1255-1275. reid. d. f.. key. r . m. & schink. d. r . 1979: radium. thorium and actinium cxtraction from seawater using an improved manganese-oxide coated fiber. eorrh planer. scr. lerr. 4 3 . 2 2 s 2 2 6 smethie. w . m . . j r . . takahashi. t. & chipman. d. w . 1985: gas exchange and co: flux in the tropical atlantic ocean dctcrmined from ?:'rn and p c o ? measurements. j. ceophys. res 90. 7001-702?. smith. s d.. muench. r . d. & peasc. c . h . 1990: polynas and leads. an ovcrview of physical processcs and environment. j. geoplijs. res. 95. 9461-9379. wallace. d. w. r . . moorc. r . m. & jones. e. p. iy87: ventilation of the arctic ocean cold halocline: rates of dia pycnal and isopycnal transport. oxygen utilization and pri mary production inferrcd using ehlorofluoromethane distributions. d e e p s e a res. 34. 1957-1979. no job name the parasitic tick ixodes uriae (acari: ixodidae) on seabirds from spitsbergen, svalbardpor_117 399..402 stephen james coulson,1 erlend lorentzen,2 hallvard strøm2 & geir wing gabrielsen2 1 department of arctic biology, university centre in svalbard, no-9171 longyearbyen, norway 2 norwegian polar institute, polar environmental centre, no-9296 tromsø, norway abstract the parasitic tick ixodes uriae was recorded from brünnich’s guillemots (uria lomvia) at two colonies on spitsbergen, the principal island in the arctic archipelago of svalbard. six brünnich’s guillemots from 30 studied at the ossian sars seabird colony were found to be parasitized. a tick was also collected from below the larger fuglehuken colony. however, ticks were not seen on brünnich’s guillemots examined at the smaller krossfjorden colony, and neither were they observed in two black-legged kittiwake (rissa tridactyla) colonies (blomstrandhalvøya and krykkjefjellet). it is suggested that either the tick has only recently been established in svalbard or the population has increased from a low level, and has consequently become visible to small-scale sampling studies. implications for the seabird population of the northern barents sea are discussed. keywords guillemot; ixodes; spitsbergen. correspondence s.j. coulson, department of arctic biology, university centre in svalbard, p.o. box 156, no-9171 longyearbyen, svalbard, norway. e-mail: steve.coulson@unis.no doi:10.1111/j.1751-8369.2009.00117.x the bird tick ixodes uriae (white, 1852) (acari: ixodidae) is a common ectoparasite of many species of colonial seabird and, although displaying local adaptation to its seabird host, has a circumpolar distribution in both the arctic and antarctic (mccoy et al. 2005). the tick is known from bjørnøya (bear island), the southern outlying island of the svalbard archipelago, where it was first observed in 2002 on common guillemot (uria aalge). it is likely that the tick is also present on brünnich’s guillemot (uria lomvia) and glaucous gull (larus hyperboreus) from bjørnøya (h. strøm, unpubl. data). the tick had previously only been observed once in the main part of the svalbard archipelago, with one larva being found on a black-legged kittiwake (rissa tridactyla) from the 61 blacklegged kittiwake and six brünnich’s guillemot chicks searched at ossian sarsfjellet, on the island of spitsbergen, in 1999 (mccoy 2001). with this exception, the tick has not been recorded on seabirds from spitsbergen (g.w. gabrielsen, pers. obs.; coulson 2007). indeed, although they may harbour a range of mallophaga (mehl et al. 1982) and parasitic gut nematodes (sagerup et al. 2000), the majority of the seabirds on spitsbergen are relatively clean of ectoparasites. of the 28 species of bird that breed regularly in svalbard (strøm & bangjord 2004), the brünnich’s guillemot is one of the most numerous, and has a wide circumpolar distribution, occurring at latitudes between 46 and 82°n (strøm 2006). breeding takes place on cliff ledges, and brünnich’s guillemot colonies in svalbard can attain a population of more than 100 000 pairs (strøm 2006). infestation with i. uriae may have debilitating effects on the host, including acting as a vector for several viral and bacterial pathogens (nunn et al. 2006; larsson et al. 2007; staszewski et al. 2007), reduction of host haematocrit (wanless et al. 1997) and sub-lethal behavioural changes (boulinier & danchin 1996; mangin et al. 2003). these effects influence the population dynamics of the seabirds, and hence the presence of i. uriae on spitsbergen is important for the seabird ecology of the northern barents region. materials and methods during july 2007, brünnich’s guillemots and blacklegged kittiwakes from the kongsfjorden region of spitsbergen (fig. 1) were hand-searched for ticks. spitsbergen, approximately 76.5–80°n, 10–21°e, is the main island of the svalbard archipelago. brünnich’s guillemots were examined from four colonies, two close to the settlement of ny-ålesund, one from ossian sars and one from krossfjorden, in the vicinity of flakbreen (fig. 1). in addition, birds were observed from a distance at polar research 28 2009 399–402 © 2009 the authors 399 mailto:coulson@unis.no fuglehuken. black-legged kittiwakes were examined from two colonies in kongsfjorden: blomstrandhalvøya and krykkjefjellet (fig. 1). the brünnich’s guillemot colonies at ossian sars (1100 individuals; table 1; scrib 2007) and fuglehuken (50 000 individuals) are considerably larger than the krossfjorden colony, where the population is estimated to be 220 individuals. moreover, at fuglehuken, there are also 4000 pairs of black-legged kittiwakes (scrib 2007), as well as small numbers of northern fulmars (fulmarus glacialis), common guillemots, common eiders (somateria mollissima), little auks (alle alle), atlantic puffins (fratercula arctica), glaucous gulls, arctic skuas (stercocarius parasiticus) and barnacle and pink-footed geese (branta leucopsis and anser brachyrhynchus). at ossian sars, blacklegged kittiwakes are present in addition to brünnich’s guillemots (scrib 2007). the two black-legged kittiwake colonies searched are also small, with blomstrandhalvøya and krykkjefjellet having ca. 966 and 637 pairs, respectively (scrib 2007; table 1). searching seabirds for ticks was undertaken in conjunction with other projects, and, initially, birds were not captured specifically to assess parasite prevalence. on 6 and 7 july 2007, 30 brünnich’s guillemots from the ossian sars colony were hand-searched for ticks. the life stages of the feeding ticks were not recorded. at krossfjorden, 39 brünnich’s guillemots were caught. ten birds (six males and four females) were searched systematically, whereas the remaining 29 birds were subject to a brief inspection for ticks. engorged adult ticks are readily observed, even under plumage, because of their large size. black-legged kittiwakes, both adults and chicks (30 individuals per colony), were also searched during the same field season from colonies at krykkjefjellet and blomstrandhalvøya. results six brünnich’s guillemots from the ossian sars colony were infested by feeding ticks (table 1), mostly at the top fig. 1 location of the colonies sampled on spitsbergen, svalbard: (1) fuglehuken; (2) krossfjorden, in the vicinity of flakbreen; (3) blomstrandhalvøya; (4) ossian sars; and (5) krykkjefjellet. table 1 summary of the colonies studied (data from this study or scrib 2007). (+ = present but in low numbers) colony location number of brünnich’s guillemots number of black-legged kittiwakes. (breeding pairs) number of little auks number of atlantic puffins number of common guillemots number of birds searched birds infested (%) fuglehuken 78°53′n, 10°32′e 50 000 4000 presenta presenta presenta 0 0b krossfjorden 79°09′n, 11°51′e 220 39 0 ossian sars 78°56′n, 12°29′e 1100 1300 30 20 blomstrand-halvøya 78°59′n, 12°08′e 966 30 0 krykkjefjellet 78°54′n, 12°12′e 637 30 0 apresent, but in low numbers. bone tick collected from under the birdcliffs. ixodes uriae (acari: ixodidae) on seabirds s.j. coulson et al. polar research 28 2009 399–402 © 2009 the authors400 of the legs. at fuglehuken, one live, fully engorged tick was collected fortuitously from grass under these bird cliffs on 23 june 2007. no ticks were found at the krossfjorden, blomstrandhalvøya or krykkjefjellet colonies. discussion the seabird colonies of kongsfjorden, svalbard, have been studied in detail since the early 1980s. nonetheless, previous studies involving the direct handling of the seabirds failed to detect the presence of i. uriae, with the exception of that of mccoy (2001), who, after examining 61 blacklegged kittiwakes at ossian sarsfjellet, found one larva on a chick, in 1999. in the summer of 2007, i. uriae was observed in the two larger brünnich’s guillemot colonies of the three colonies studied. the age of a colony has been implicated in the level of infestation by i. uriae (danchin 1992), but this seems unlikely to be of importance here, as all the colonies in the present study were well established. however, it has also been previously observed that parasite density can vary greatly, even within a colony (mccoy et al. 2003), and it may be that the presence of the tick at krossfjorden was overlooked because of the limited sampling. no black-legged kittiwakes, adults or chicks, were seen to be parasitized at the two colonies studied. the presence of i. uriae on spitsbergen may have debilitating consequences for the seabird population of the northern barents. for example, the feeding of the tick is known to reduce the haematocrit (wanless et al. 1997), and it has been suggested that during extreme infestations, the loss of blood can lead to the death of the host (gauthier-clerc et al. 1998). i. uriae may also have sublethal behavioural effects that result in reduced breeding success (mangin et al. 2003). high levels of infestation result in black-legged kittiwakes abandoning historical breeding sites and founding new colonies (boulinier & danchin 1996), but these new colonies may be at less favourable locations, thereby reducing the overall fitness of the colony. seabirds in the arctic may already be under significant levels of stress, resulting from the lack of food, pollutants and climate change (sagerup et al. 2000; gabrielsen 2007; sandvik et al. 2005); any additional stress factor may exacerbate the existing effects, with unpredictable results on seabird populations. ixodes uriae occurs throughout the seabird colonies of norway (mehl & traavik 1983), and it is interesting to ask why i. uriae is now being observed on spitsbergen. there are several possible answers. (i) the tick has always been present, but not previously observed. despite seabirds being handled every year since the early 1980s, in studies often involving ringing and blood sampling, as well as in investigations aimed at detecting the tick, i. uriae has only once been recorded previously on spitsbergen (mccoy 2001). if the tick was resident previously, its density must have been low, and we are now observing an increasing population. nonetheless, it must be recognized that only one study has previously been targeted at collecting ticks (mccoy 2001), and because of the difficulties in sampling birds in svalbard, only a limited number of individuals were searched. (ii) the levels of persistent organic pollutants are rising. persistent organic pollutant (pop) levels in many populations of arctic seabirds are rising (gabrielsen 2007), and this has a negative effect on their immune systems, resulting in an elevated gut parasite load (sagerup et al. 2000). given that the immune response restricts tick development by impairing engorgement, ova production and viability (wikel 1996), increased pops may result in greater i. uriae infestation rates among arctic seabirds. (iii) ticks were introduced by birds from other colonies. infested prospecting birds may recently have moved north, bringing the tick with them. (iv) climate change enables ticks to survive the winter. i. uriae is thought to be freezing intolerant, and, with the exception of the egg stage, cannot survive temperatures below -12°c (lee & baust 1987). the recent relatively mild winters, with no sea-ice formation in kongsfjorden, may have enabled greater overwintering success. in conclusion, the bird tick i. uriae has recently been observed on brünnich’s guillemots on spitsbergen. if it is a new arrival, it may spread to other breeding bird species and populations, and is likely to affect the ecology of the seabird population in the northern barents sea. further studies that examine svalbard seabirds for this parasite are called for. acknowledgements the authors thank the mariclim (165112/s30) and copol (176073/s30) projects for assistance in gaining access to the birds and collecting the ticks, and the assistance of kjetil letto and gry gasbjerg with fieldwork. the comments of rob barrett on a draft manuscript were appreciated. malin daase assisted with the preparation of fig. 1. references boulinier t. & danchin e. 1996. population trends in kittiwake rissa tridactyla colonies in relation to tick infestation. ibis 38, 326–334. coulson s.j. 2007. the terrestrial and freshwater invertebrate fauna of the high arctic archipelago of svalbard. zootaxa 1448, 41–58. danchin e. 1992. the incidence of the tick parasite ixodes uriae in kittiwake rissa tridactyla colonies in relation to the age of the colony and a mechanism of infecting new colonies. ibis 134, 134–141. ixodes uriae (acari: ixodidae) on seabirdss.j. coulson et al. polar research 28 2009 399–402 © 2009 the authors 401 gabrielsen g.w. 2007. levels and effects of persistent organic pollutants in arctic animals. in j.b. orbaek et al. (eds.): arctic alpine ecosystems and people in a changing environment. pp. 377–412. berlin: springer. gauthier-clerc m., clerquin y. & handrich y. 1998. hyperinfestation by ticks ixodes uriae: a possible cause of death in adult king penguins, a long-lived seabird. colonial waterbird 21, 229–233. larsson c., comstedt p., olsen b. & bergstrom s. 2007. first record of lyme disease borrelia in the arctic. vector bourne zoonotic diseases 7, 453–456. lee r.e. & baust j.g. 1987. cold-hardiness in the antarctic tick ixodes uriae. physiological zoology 60, 499–506. mangin s., gauthier-clerc m., frenot y., gendner j.p. & le maho y. 2003. ticks ixodes uriae and the breeding performance of a colonial seabird king penguin aptenodytes patagonicus. journal of avian biology 34, 30–34. mccoy k.d. 2001. consequences of dispersal in host–parasite systems: population dynamics, genetic structure, and local adaptation of the seabird tick ixodes uriae. phd thesis. pierre and marie curie university, paris. mccoy k.d. chapuis e., tirard c., boulinier t., michalakis y., le bohec c., le maho y. & gauthier-clerc m. 2005. recurrent evolution of host-specialized races in a globally distributed parasite. proceedings of the royal society of london series b 272, 2389–2395. mccoy k.d., tirard c. & michalakis y. 2003. spatial genetic structure of the ectoparasite ixodes uriae within breeding cliffs of its colonial seabird host. heredity 91, 422–429. mehl r., bang c., kjos-hanssen b. & lie h. 1982. mallophaga from svalbard. fauna norvegica series b 29, 19–23. mehl r. & traavik t. 1983. the tick ixodes uriae (acari, ixodides) in seabird colonies in norway. fauna norvegica series b 30, 94–107. nunn m.a., barton t.r., wanless s., hails r.s., harris m.p. & nuttall p.a. 2006. tick-borne great island virus: (i) identification of seabird host and evidence for co-feeding and viraemic transmission. parasitology 132, 233–240. sagerup k., henriksen e.o., skorping a., skaare j.u. & gabrielsen g.w. 2000. intensity of parasitic nematodes is associated with organochlorine levels in the glaucous gull (larus hyperboreus). journal of applied ecology 37, 532–539. sandvik h., erikstad k.e., barrett r.t. & yoccoz n.g. 2005. the effect of climate on adult survival in five species of north atlantic seabirds. journal of animal ecology 74, 817–831. scrib 2007. seabird colony registry of the barents and white seas. unpublished database. tromsø: norwegian polar institute. staszewski v., mccoy k.d., tveraa t. & boulinier t. 2007. interannual dynamics of antibody levels in naturally infected long-lived colonial birds. ecology 88, 3183–3191. strøm h. 2006. birds of svalbard. in k.m. kovacs (ed.): birds and mammals of svalbard. polarhåndbok 13. pp. 86–191. tromsø: norwegian polar institute. strøm h. & bangjord g. 2004. the bird and mammal fauna of svalbard. in p. prestrud et al. (eds.): a catalogue of the terrestrial and marine animals of svalbard. skrifter 201. pp. 123–135. tromsø: norwegian polar institute. wanless s., barton t.r. & harris m.p. 1997. blood hematocrit measurements of four species of north atlantic seabirds in relation to levels of infestation by the tick ixodes uriae. colonial waterbird 20, 540–544. wikel s.k. 1996. host immunity to ticks. annual review of entomology 41, 1–22. ixodes uriae (acari: ixodidae) on seabirds s.j. coulson et al. polar research 28 2009 399–402 © 2009 the authors402 thermal hysteresis antifreeze agents in fishes from spitsbergen waters john-peder denstad, t o r e aunaas, jan fredrik borseth, a r n e vollan aarset and karl erik zachariassen denstad, j.-p., aunaas, t . , borseth, j. f., vollan aarset, a. & zachariassen, k. e. 1987: thermal hysteresis antifreeze agents in fishes from spitsbergen waters. polar research 5 n.s., 171-174. the occurrence of macromolecular antifreeze agents (so-called thermal hysteresis factors) in blood plasma of fishes from spitsbergen waters was investigated in august 1983, october 1984, and january 1986. thermal hysteresis was found in the plasma of three species of spitsbergen fishes: shorthorn sculpin (myoxocephalw scorpiw), polar cod (boreogadw saidu), and sea snail (lipuris lipuris). this is the first time thermal hysteresis is reported from the sea snail. seasonal changes in the amount of thermal hysteresis were observed in blood plasma of the shorthorn sculpin and the sea snail. with the exception of the polar cod, blood plasma of deep water fishes displays no thermal hysteresis. the reason for this is probably that the polar cod also occurs in shallow ice laden sea water, where an 'antifreeze' would be needed to protect against inoculative freezing. no thermal hysteresis was observed in blood plasma of the saithe (pollachim virens), despite the fact that the saithe was observed swimming in ice laden sea water at a temperature of -1 to -1.5"c under natural conditions, and was rapidly killed when it came into contact with ice in the laboratory. it is not known how the saithe survives in ice laden water under natural conditions. john-peder denstad, tore aunaas, jan fredrik borseth, arne vollan aarset and karl erik zocharimsen. departmen) of zoology, a v h . universify of trondheim. 7055 drugvoll. norway; november 1986 (revised augrlst 1987) most species of teleost fish which inhabit tem perate marine waters have blood plasma melting points (mps) within the range -0.6 to -023°c (holmes & donaldson 1969). in the absence of ice, such fishes are capable to survive supercooling of 2 to -3°c. however, if ice is present, the supercooled fishes will immediately freeze and die due to inoculation of ice through the skin (scholander et al. 1957). polar oceans are char acterized both by subzero water temperatures and the presence of ice. since many marine fishes spend their entire iife in these regions, they must possess specialized means of protecting them selves from freezing. investigations have shown that many subpolar and polar fishes possess pro teinaceous antifreeze agents, i.e. so-called ther mal hysteresis factors (thf), (devries 1971; devries & lin 1977; duman & devries 1975). they act in a non-colligative way by causing a separation of melting point and freezing point (thermal hysteresis) of frozen samples of body fluid, so that ice crystals are prevented from grow ing upon cooling until a temperature lower than the melting point is reached. at this temperature, which is called the hysteresis freezing point (hfp), a rapid growth of ice crystals is observed. this study presents information about the con tent of t h f in 16 species of fish from shallow and deep water at spitsbergen. material and methods sample collection the fishes were collected in the vicinity of ny h e s u n d , spitsbergen, in august 1983, late october 1984, and in january 1986. shallow water fishes were collected by means of bow-nets and jigging at depths of 1-5 m. deep water fishes were caught at a depth of 180 m from a trawler. blood was collected from the caudal vein and artery by sucking it into glass capillary tubes by means of the capillary forces. after centrifugation on a compur m 1100 micro centrifuge the plasma was sealed from air by a layer of paraffin oil, as described by zachariassen et al. (1982), and frozen for later analysis. determination of melting point and hysteresis freezing point the melting points and hysteresis freezing points of the blood plasma of the animals were deter 172 j . p . denstad et al. table 1 . the blood plasma hysteresis freezing points (hfp), melting points (mp), and amount of thermal hysteresis (mp-hfp) in several species of arctic fish at different seasons. values are mean tsd. numbers of specimens are given in parentheses. date species family fishing ground hfp mp mp-hfp depth (m) ("c) ("c) ("c) august myoxocephalw scorpius (1) cottidae 3 -1.36 -0.78 0.58 1983 gadur morhua (3) gadidae melanogrammu aeglefinus (2) gadidae boreogadus saida (3) gadidae hippoglossoides platersoides (2) pleuronectidae sebastes marinus (3) scorpaenidae lycodes esmarki (1) lycodidae october eumicrotremus spinosw (1) cyclopteridae 1984 mallotus oillosur (1) osmeridae triglops pingeli (3) cottidae anediellus uncinatus (2 1 cottidae leptagonus decagonus (1) agonidae a g o n w cataphractus (1) agonidae boreogadus saida (1) gad i d a e october pollachiw oirens (1) gadidae 1984 myoxocephalus scorpius (2) cottidae liporis liporis (2) liparididae 180 180 180 180 180 180 180 180 180 180 180 180 -0.90 -t 0.14 -0.93 -1.94 ' 0.47 -0.78 -0.95 -t 0.08 -0.84 -0.79 -1.09 -0.92 5 0.30 1.05 -o.% -1.20 -0.90 2 0.14 -0.93 -0.80 ' 0.33 -0.78 -0.95 f. 0.08 -0.84 -0.79 -1.09 -0.92 2 0.30 -1.05 -0.96 -1.20 0 0 1 . 1 4 k 0.59 0 0 0 0 0 0 0 0 0 1-3 1-3 1-3 1-3 -1.66 -0.70 -1.81 -1.34 1 . 1 1 -0.70 -0.76 -0.73 0.55 0 1.05 0.61 january myoxocephalus scorpiur (1) cottidae 1-3 -1.71 -0.77 0.93 1986 boreogadus saida (3) gadidae 1-3 -2.19'0.09 1 . 1 2 ? 0 . 0 2 1.06'0.08 liporis liparis (4) liparididae 1-3 1 . 9 0 t 0.11 -0.92 -t 0.08 0.98 t 0.04 mined by using a clifton nanolitre osmometer as described by zachariassen 6i husby (1982a). the melting process of 3 0 n l samples was observed in a microscope, while the temperature of the samples was regulated with an accuracy of *o.ool"c. t h e temperature at which the last tiny ice crystal disappeared during slow warming of the prefrozen sample was taken as the melting point. plasma samples containing a tiny seeding ice crystal were then cooled. and the temperature at which a rapid growth of ice crystals took place was taken as the h f p (devries 1971). survival of shallow water fishes during contact with ice in an additional experiment a volume of 10 litres of seawater was cooled and partly frozen at a temperature of -1.6"c. shallow water fishes of three different species were put in the ice laden sea water and their behaviour observed. results the mps. the hfps, and t h e amount of thermal hysteresis in the blood plasma of fishes from spitsbergen are shown in table 1. t h e data reveal that all d e e p water species investigated in the autumn had blood plasma mps in t h e range of 1.09 to -0.78"c. all shallow water fishes inves tigated in t h e summer, autumn, a n d winter had mps in t h e range of -1.12 t o -0.70"c. in most of the species caught at d e e p water, the h f p of the blood plasma corresponds to the mp, indicating that thfs were absent from their plasma. however, t h e blood plasma of polar cod (boreogadus saida) showed a hysteresis of about l . l " c , revealing the presence of thf in the blood plasma of this species. plasma from the arctic shorthorn sculpin (myoxocephalus scorpius), collected in shallow water in august 1983, had a n m p of -0.78"c, and a hysteresis (0.58"c) was present (table 1). blood plasma of polar c o d , arctic shorthorn sculpin, and sea snail (liparis liparis) collected in shallow water in late october showed a thermal hysteresis of 0.55, 1.05, and 0.61"c, respectively, indicating that thfs are present in the blood plasma of these species. t h e hysteresis effect in the blood plasma of m . scorpius was significantly antifreeze agents in fishes from spitsbergen 173 table 2. survival time of three species of arctic fish in ice laden sea water in october. values are mean +sd. number of specimens are given in parentheses. species water survival temperature time ("c) (min.) pollachius oirem ( 2 ) -1.6 0 myoxocephalus scorpius (1) ice 63 boreogadus saida ( 2 ) present 30 greater in specimens collected in october than in those collected in august. in saithe (pollachius uirens), collected in shallow water in late october, the hfp corresponded to the mp, indicating that thfs are absent from the blood plasma. the mp and the hfp in the blood plasma of sea snail collected in shallow water were substantially lower in animals collected in january than in animals collected in october, and the thermal hysteresis effect was stronger in january than in october (table 1). the hfp in the blood plasma of polar cod collected in shallow water was lower in january than in october. the hysteresis effect was also stronger in january than in october (table 1). on the contrary, for the shorthorn sculpin there were no differences in any of the parameters from october to january (table 1). the survival times of the fish exposed in ice laden sea water in late october are shown in table 2. sea water was supercooled and then seeded with a few ice crystals. the sea water was then immediately filled up with a whole flurry of ice crystals. the temperature was -1.6"c. one individual of saithe froze and died immediately when put into the ice laden sea water, whereas polar cod and arctic shorthorn sculpin survived for 4 hour and 1 hour, respectively. discussion eleven out of twelve deep water fish species from spitsbergen showed no thermal hysteresis in their blood plasma in the autumn (table 1). these fishes could survive the winter in a supercooled state since they would not come into contact with seeding ice (scholander et al. 1957). however, plasma from polar cod caught at deep water showed hysteresis. the reason for this may be that the polar cod is also found in shallow ice laden water, where an 'antifreeze' effect would be needed to protect against inoculative freezing. the presence of thfs has been reported in some deep water fish species also in previous studies (duman & devries 1975). the present observation of thfs in the blood plasma of sea snail ( l . liparis) is the first obser vation of such antifreeze agents in this species. blood plasma of sea snail, collected in shallow water, also showed a seasonal change in the t h f from -1.34"c in october to -1.90"c in january (table 1). in the same period the mp of the blood plasma was lowered by about 0.2"c. thus, thermal hysteresis effect in the blood plasma of the sea snail increased by about 60% from octo ber to january. this probably reflects a better protection against both the lower water tem peratures prevailing in the winter and the pres ence of more ice. blood plasma of shorthorn sculpin, collected in shallow water, displayed thermal hysteresis in the summer, autumn, and winter (table 1). the maintenance of plasma antifreeze proteins throughout the year appears to be a feature com mon to a number of fish species residing in polar and sub-polar oceans (fletcher et al. 1982). dur ing the summer months the alaskan sculpin (myoxocephalus uerrucosus) loses 50% of its winter levels of antifreeze, probably reflecting the higher water temperature of 7°c at this time (devries 1980). in the blood plasma of shorthorn sculpins from spitsbergen the thermal hysteresis effect increased by about 6&80% from august to october. individuals of saithe were collected in shallow water containing ice. no thermal hysteresis was observed in the blood plasma of this species (table 1). previous studies have shown that some bottom living fish species from shallow frozen bays in nova scotia do not have a thermal hys teresis effect in their blood plasma. these fish probably survive simply by avoiding contact with the surface ice (duman & devries, 1975). fish species with no 'antifreeze' in their blood plasma are capable of surviving supercooling of 2 to -3°c in the absence of ice. however, if ice is present, ice crystals appear t o penetrate the outer epithelium and cause the supercooled fish to freeze and die immediately (scholander et al. 1957). the present experiments at spitsbergen show that the saithe died immediately when put in ice laden sea water at a temperature of 1.6"c (table 2), whereas the polar cod and the short 174 j . p . denstad et al. horn sculpin survived for about f and 1 hour, respectively. this is in good agreement with the fact that thfs are lacking in the blood plasma of the saithe and that thfs are present in the blood plasma of the polar cod and the shorthorn sculpin. these observations support the view that thfs are important to prevent inoculative freezing, in the same way that previous work has shown that thfs play an important role in hibernating freeze-sensitive insects (zachariassen & husby 1982b). acknowledgemenn. this study was made possible by econ omic support from the norwegian polar research institute. the norwegian rescarch programme for marine arctic ecology (pro mare), the oil company fina. and the department of zoology. university of trondheim. we also want to thank the crew onboard the trawler 'nordstjernen' from the faroe islands. who provided us with deep water fishes. references devrie\. a . l 1971: glycoprotcins as biological antifrccze agent\ i n antarctic fkhes. science. a). y 172, 1152-1 155 devriek. a . l . l9xo: biological antifreeze\ and survival i n freezing environments. pp. 58s607 in gillcs. r. ( c d . ) : ani malr and environmental firness 1 . pergamon press, toronto. devries. a. l . & lin. y . 1977: the role of glycoprotein antifreezes in the survival of antarctic fishes. pp. 439-458 in llano, g. a . (cd.): adaptations within antarctic ecosystems. proceedings of the third scar symposium on antarctic biology. gulf publishing co., houston. duman, j . g . & devrics, a . l. 1975: the role of macro molecular antifreezes in cold water fishes. comp. biochem. fhysiol. 52a, 19?-199. fletcher. g. l . . addison, r. f.. slaughter, d. & hew. c. l. 1982: antifreeze proteins in the arctic shorthorn sculpin (myoxocephalus scorpiur). arctic. 35 (2), 302-306. holmes. w. n . & donaldson, e . m . 1969: the body com partments and distrihution of electrolytes. pp. 1-89 in hoar, w . s . & randall, d. s. (cd5.): fish physiology 1. academic press, new york. scholander, p. f . , van dam. l . , kanwishcr, j . w . . hammel. h. t . & gordon. m . s. 1957: supcrcooling and osmo regulation in arctic fish. j . cell. comp. fhysiol. 4y. 5-24. zachariassen. k . e . , baust. j . g . & lee. r . e . jr. 1982: a method for quantitativc determination of ice nucleating agents in insect hcmolymph. cryobiology 19, 18c184. zachariassen. k. e. & husby, j . a . 1982a: antifreeze effect of thermal hysteresis agents protects highly supercoolcd insects. nature 298, 865-867. zachariassen, k. e . & husby. j . a. 1982b: stabilization of highly supercooled insects by thermal hysteresis agents. (abstract from symposium on invertebrate cold-hardiness, oslo 1982.) cryo-letters 3 , 316. karstic surface in the lower permian sabkha sequence of the gipshuken formation, central spitsbergen, svalbard 0 r n u l f lauritzen lauritzen, 0. 1983: karstic surface in the lower permian sabkha sequence of the gipshuken formation. central spitsbergen, svalbard. polar research, i n.s., 157-160. some unusual karst structures occur in the upper part of the evaporite-dominated sequence of the gipshuken formation. this lower permian unit is characterized by interbedded anhydrite and dolomites, and is now interpreted in terms of superimposed sabkha cycles. the karst structures are found in the inner part of skansdalen in dickson land, and have not yet been observed elsewhere in corresponding horizons in svalbard. these structures, often seen as linked hemispheroids. consist of almost pure anhydrite and are here interpreted as representing the remnants of consolidated sabkhas; the original sabkha plain was flooded and partly dissolved, and abandoned channels between the hemispheroidal structures were then filled with sediments of later sabkha cycle. the younger sediments which f i l l the relief between and above the structures contain small enterolithic folds which indicate primary formed anhydrite. anhydrite is still the most common subsurface mineral in these sulphatic deposits. an3 there is no evidence of gravitational or tectonic movements within these beds 0rnulf laurirzen, norsk polarinstitutt, p . 0. box 158, 1330 oslo lufthaun. norway; march 1982 (revised june 1982) during the summer of 1977 a field party from norsk polarinstitutt’s expedition visited skans dalen (fig. l ) , in the eastern part of dickson land, in order to investigate sediments of the gipsdalen group. the lower permian evaporites l o c a t i o n m a p p of the gipshuken formation (cutbill & challinor 1965) were studied in detail and a horizon with unusual hemispheroidal structures was found (fig. 2) in the upper part of this sulphatic sequence (fig. 3). these structures are located in the westernmost part of skansdalen where a stream has eroded a cliff section through the upper part of the evaporitic sequence. the studied structures are restricted to the top of the evaporite-dominated beds of the gipshu ken formation; they are overlain by approxi mately 115 metres of dolomites with scattered sulphate nodules which are sharply bounded from the overlying voringen member of the kapp sta rostin formation (fig. 3). the gipshuken for mation is exposed in gently dipping sequences in the area north of isfjorden, and the formation was originally assigned t o the ‘upper gypsiferous series’ of the permo-carboniferous by gee, har land & mcwhae (1953). the formation comprises greyish dolomites intercalated with bedded and nodular sulphates. the gipshuken formation is generally assigned to the artinskian stage of the lower permian, a period of general regression in svalbard. sediments of the gipshuken for mation suggest shallow to restricted marine fig. i . location map with place names mentioned in the text. 158 0rnulf lauritzen environments throughout the svalbard archipel ago during the artinskian; areas with evaporitic beds (e.g. north of isfjorden) represent lagoonal to supratidal environments with superimposed sabkha cycles (lauritzen 1981) and short periods of shallow marine deposition. description the surface and its structures described here are all restricted to the upper part of one single con tinuous anhydrite bed which can be followed lat erally for several hundred metres. this bed, the uppermost prominent anhydrite horizon, is about 1 m thick in the intervals between the rises or hemispheroids, though these structures them selves have up to 3 m relief. the most well-devel oped of these structures is found innermost in skansdalen (fig. 2). and is about 4 m high in the observed section. this single section gives no information o n the three-dimensional shape of these structures. however. smaller but similar structures are exposed in the same cliff and bed, and show lateral separation in order of tens of metres. exposures which show more than two-dimen sional cross-section indicate an almost hemis pheroidal shape. it is possible, however, that some of the structures may have a more elon gated, ridge-like geometry. the hemispheroids or ridges themselves display few internal struc tures. the anhydrite is white, pure and homo geneous. quite unlike many of the other sulphatic beds lower in the formation which show chicken-wire structures (lauritzen 1981). the nature of the upper surface and of the contact with the siderock are important aspects of these structures. the upper surfaces are usually smooth. but the upper left part of the feature shown in fig. 2 contains a depression filled with darker sediment. note also the overhang on the upper right side seen in the same figure. the siderock on either side of this hemispheroid is quite different; it consists of dark, thinly bedded dolomite with almost no anhydrite to the left, while on the right side of the section (fig. 2 ) it is sulphatic with enterolithic folds and minor finely laminated beds of dolomite. the sediments abut both sides of the hemispheroid with a sharp angular disconformity. but rest comformably on the top of the structure. the hemispheroidal structures observed aver age about 1 m in height, but vary from the largest about zm high, (fig. 2), to minor irregularities on the upper surface of the sulphate bed. the dolomitic sediments found in connection with the structures contain several of the development fea tures of gypsum/anhydrite described by lauritzen (1977). the tubes (subtype iic) are here positive infillings in burrows, and are found in association fig. 2. the highest of the hem ispheroidal structures on the karstic surface, as exposed in skansdalen, svalbard. karstic surface in sabkha sequence 159 with cross-bedding and ripple marks, reflecting a shallow energetic environment. chem or slbclfied sedllnents do m n d t e in the lower transgressive inember, fosvllferous iimeftoneb arc mainly doloniite often algal lami nated sulphdtc mostly found a s s: nodules but continuous beds also discussion although at a distance the hemispheroidal struc tures appear to be miniature growth diapirs, their relationship to the associated beds rules out this interpretation; the total facies association also excludes tectonic forces as a mechanism produc ine diadirs. erosive surfaces are common in eva rfaie rcstr,cted to u p p r r l n o ~ t part of the cvaporlre donunatrd srqucnce legend: chert and s ~ l i c t f i e d rocks mostly dolomtr ;t~hy:,r,,;c ~ i i l ~ r h c d d ~ d w i t h fig. 3. stratigraphic setting of t h e karstic surface exposed in skansdalen. v i poritic sequences of the sabkha type, as described by e.g. kendal (1979), but documentation of the gipshuken formation elsewhere (lauritzen 1981) has yielded few erosion or solution surfaces. the studied surface is interpreted here as a karstic surface, an interpretation not inconsistent with a general sabkha setting, here illustrated in fig. 4. (a) precipitation of anhydrite in a supratidal coastal sabkha environment, ultimately pro a a a a a a a aaaaaaaaaaaaaaa a a a a a a a a a ~ a ~ \ a ~ a ~ a ~ a ~ a ~ a a a a a a a a deposition of anhydrite in a supra tidal sabkha environment, produc ing a thick, continuous bed. end of a s a b k h a c y c l e . transgression and partial solution of the sabkha. leaving an irregular o r undulating channelled surface a a a a a a a a a a a a a a a a , a a a a a a a a a a a a a a a a a within the mtertidal zone. tidal flats established o n top of the partly dissolved anhydrite sur face. with deposition of calcareous mud (often algal laminuted) he tween the heinispheroids. further solution o f the emergent parts of the anhydrite. beginning of a new sabkha cycle. ) a a a a a a a a a a a a a a a a a fig. 4 . steps in the development = s of the karstic surface in anhy drite, a s s e e n in the gipshuken formation in skansdalen, , a a a a a a svalbard. p a a a , a a a a a a a a a a a a a a a a a 160 0rnulf lauritzen ducing a thick. continuous bed which rep resents the culmination of a sabkha cycle. this bed must have had a primary minimum thickness of about 3 metres. (b) the sabkha surface was subsequently trans gressed or flooded by sea water. this resulted in partial dissolution and an irregular, undu lating upper surface with hemispheroidal or ridge-like structures. (c) partial emergence and establishment of a tidal flat environment on the karstic t o p of the anhydrite unit led to deposition of calcareous mud. often algal laminated in the hollows (channels) between the remaining positive structures. solution of the higher. exposed parts of the structures continued. and dis solved anhydrite was partlv reprecipitated in the siderock. beginning of a new sabkha cycle. (d) further deposition of anhydrite within algal mats. producing thin layers, smaller nodules and enterolithic folds. t h e whole structure was now covered. and smaller depressions within its top were filled with sediments before total burial. a c k n o w l e d g e m e n t s . i thank dr. david worsley for his cri ticism and help and for improving the english text. thanks also to espen kopperud for help with the final figure drafting. references cutbill. j. l. & challinor. a . 1965: revision of the stratigraph ical scheme for the carboniferous and permian rocks of spitsbergen and b j ~ r n ~ y a . geol. m a g . 102, 418-439. gee, e . r.. harland. w b . & mcwhae. j . r . h. 1953: geology of central vestspitsbergen part i . review of the geology of spitshergen with special reference to central vestspitsbergen; p a n 11. carboniferous and lower permian of billefjorden. trans. r . soc e d i n b . 63. 299-356. kendal. a . c . 1979: continental and supratidal (sabkha) eva porites. i n walker. r. g ( e d . ) : facies models. geoscience c a n a d a , reprint series 1. lauritzen. 0. 1977: development patterns of gypsudanhydrite in lower permian sediments of central spitsbergen a sug gested classification. n o r s k polarinst. a r b o k 1976. 5-20. lauritzen. 0. 1981: development of the gipshuken formation (lower permian) at trollfuglfjella in central spitsbergen, svalbard. n o r s k polarinst. s k r . 176. geology of gjelsvikfjella and western muhlig hofmannfjella, dronning maud land, east antarctica y . o h t a , b . 0. tbrudbakken a n d k . shiraishi ohta, y . , terudbakken, b . 0. & shiraishi, k. 1990: geology of gjelsvikfjella and western miihlig hofmannfjella, dronning maud land, east antarctica. polar research 8, 99-126. as a part of the norwegian antarctic research expedition 1984185, geological mapping was performed in gjelsvikfjella and western miihlig-hofmannfjella, dronning maud land. the northern part of gjelsvikfjella is dominated by the jutulsessen metasupracriistals which have been intruded by a major gabbroic body and several generations of dykcs. to the south the metasupracrustals gradually transform into the risemedet migmatites. in western miihlig-hofmannfjella the bedrock is dominated by the large svarthamaren charnockite batholith. the batholith is bordered by the sn0toa metamorphic complex outcropping to the south and west in miihlig-hofmannfjella and it is characterized by a high content of partly assimilated country rock inclusions. mineral paragenesis and geothermometry/geobarometry suggest a two-stagc tectonothermal-igneous history with an initial intermediate pressure, upper amphibolite to granulite facics metamorphism followed by high temperature transformations related to the charnockite intrusion. thc age of the initial tectonothcrmal event is probably about 1,100 ma. geochronological work in the present study (rb/sr whole rock) gave an age of 500 2 24 ma for the svarthamaren charnockite, interpreted to record the age of crystallization. late brittle faulting and undeformed dolerite dykes outcropping in jutulscssen are believed to be related to mesozoic crustal stretching in the jutulstraumen pencksokket rift zone to the west. y . o h t a , norsk polarinstitutt, p . 0. box 158, n-1330 oslo lufthaon, n o r w a y ; b.o. t@rudhakken, saga petroleum ais, kj@rboueien 16, n-1301 sanduika, n o r w a y ; k . shiraishi, nationul lnsritute of polar research, t o k y o , japan; a p r i l 1990 (rewised august 1 9 9 0 ) . the studied area is located to 2"-5"35'e and 71"46'-72"15's, on the eastern side of the jutulstraumen-pencksokket rift zone (j-p rz) (neethling 1972) which separates a proterozoic platform to the west and high-grade metamorphic areas to the east (fig. 1). the j-p r z is a key tectonic structure in correlating this part of antarctica with the southeastern part of africa (grantham et al. 1988). metamorphic rocks in the study area were first described by roots (1953) and widespread reconnaissance mapping was undertaken by soviet geologists (ravich & soloviev 1966), who also carried out radiometric dating on the rocks (ravich & krylov 1964). a 1 : 1.5 million scale geological map has been edited by roots (1969) in the antarctic map folio series. the h.u. sverdrupfjella area to the southwest has been described by hjelle (1972). he recognized three lithological units, of which the sveabreen formation (granitized gneisses and migmatites of upper amphibolite facies) and the rootshorga formation ( psammo-pelitic, metamorphosed supracrustals) extend into the present area. grantham et al. (1988) have described the geology and petrology of northern h.u. sverdrupfjella in detail. they separated various igneous rocks from hjelle's lithostratigraphic formations and carried out some age deter minations. the oldest obtained age is about 900 ma (rb-sr whole rock) from conformable granitoids in the gneisses. late tectonic granites are about 470 ma (rb-sr whole rock). the highest grade metamorphism, possibly a late magmatic stage, is determined to about 850°c and 9-11 kb. most rocks were metamorphosedunder conditions of about 560"-690"c and 5-6 kb, followed by a retrograde overprinting. an alkaline complex near the j-p r z has been dated to about 182 ma (40ar-39ar) and 170 ma (rb-sr, allen 1990), indicating young extensional activity along the rift zone. according to ravich & krylov (1964), western muhlig-hofmannfjella consist of high-grade metasupracrustals of pre-riphean ages and a 100 y . ohta, b. 0. torudbakken & k . shiraishi fig. 1. distribution of exposures in western dronning maud land. t h e study area is in the eastern part of the map. numhcrs: radiometric ages in million years ( m a ) obtained hy various methods (kavich & krylov 1y64; krylov 1972: wolmarans & k c n t 1982; moycs 1989). analytical methods: p: pb/pb, u: u/ph. r : kh/sr, s : sm/nd, a : 4uar/3yar. k: k/ar. analyscd samples: w: whole rock, h: biotite. m: muscovite, p: phengite, c: chlorite, z: zircon, f feldspar, wm: whole rock-minerdl. granite-granosyenite complex. their k/ar and rb/sr whole rock ages range from 400 to 480 ma, with a 510 ma age from gjelsvikfjella. the norwegian antarctic research expedition 1984-85 mapped the main part of gjelsvikfjella and western miihlig-hofmannfjella. description of regional geology gjetsvikfjella in gjelsvikfjella the geological mapping covered jutulsessen, risemedet and terningskarvet. the southwestern parts, including southwest jutulsessen, nupskammen and von essenskarvet were not visited, but distant observations were made from terningskarvet towards these areas (fig. 2). three major lithologic units have been recognized: -metagabbros in northeastern jutulsessen -jutulsessen metasupracrustals -risemedet migmatites recognized: --4plite-pegmatite dykes -metabask dykes -mesozoic dolerite three subordinate dyke types were also metagabbros the metagabbro in jutulsessen occurs as an intrusive body about 7 km long and 1 km wide. geology of gjelsvikfjella and western muhlig-hofmannfjella 101 fig. 2. geological map of gjelsvikfjella, including distant observations by binoculara on the northern sidc of the fjellimcllom bakhallct glaciers, nupskammcn, gluvrekletten and von esscnskarvet. x and y i n circle: localities of the dated samples (ref. tablc 8), bt-, yo-: localities of samples i n tables 2 , 3 and 4. the rocks are medium-grained, melanocrafc, to white, aplite-pegmatite dykes, generally less hornblende-biotite gabbro, locally coarsethan 0.5 m thick. most dykes show gentle dips to grained, with no preferred orientation of the the southeast, although some have steep dips. minerals. these rocks include fine-grained similar dykes are closely associated with the cogenetic, rounded xenoliths with randomly gneisses and migmatites. oriented biotite, and are cut by numerous pink the main constituent minerals of the meta 102 y . ohta, b. 0. terudbakken & k . shiraishi gabbro are green hornblende, often dusty with opaques, and commonly including granular clinopyroxene grains. fresh dark brown biotite flakes are sometimes bent. plagioclase has normal zoning with andesine-oligoclase composition, and shows blocky and for wavy extinction. the coarse grained gabbroic facies contains a large proportion of clinopyroxene and locally carries olivine. small grains of apatite, sphene and opaques are the accessories. the contact to the jutulsessen meta supracrustals is intrusive and a wedge of the metagabbro, about 100m wide, cuts the latter north of stabben. fine-grained xenoliths, consisting of primary prismatic plagioclase and granular clinopyroxene, may be a doleritic early facies of the metagabbro. pale green hornblende surrounds the clino pyroxene grains. randomly oriented, over growing dark brown biotite may be due to secondary changes, when the rock was captured as xenoliths. an ore-rich phase which is developed in connection with the later aplite-pegmatite dykes consists of more than 80% magnetite and coarse grained microcline, plagioclase and sub idiomorphic quartz. small amounts of biotite and muscovite surround the ore grains. jutulsessen metasupracrustals micaceous and felsic gneisses are the main constituents of this lithological unit (table 1). the gneisses are found in the northern half of jutulsessen, and extend to the east, across the slithallet glacier to medmulen. the metagabbro discordantly cuts these rocks in the north, whilst on the southern side a gradational transition is observed to the risemedet migmatites. a steep e-w trending fault, the armlenet fault, offsets the rocks in northern armlenet. a) lower succession an approximately 4.5 km thick succession of gneissose and schistose rocks is exposed in the cliffs of grjotlia in western jutulsessen. the lower succession, 1.3 km in thickness, which consists of alternating felsic and micaceous gneisses, occurs below a layer-parallel shear fault in this area. the micaceous gneisses are mainly biotite bearing rocks with or without garnet. the other main minerals are microcline, ~ quartz and table 1 . lithostratigraphy of the jutulsessen metasupracrustals. mesozoic dolerites aplite pegmatites metagabhro basic dykes and sheets jutulsessen metasupracrus tals (c. 4,500m) (lateral change into the risemedct migmatites) upper succ. (700 m) middlc succ. 2,600 m) (2,200 lower succ. (1,300111) -felsic, migmatitic gneisses with biotite rich and basic .paleosomcs felsic gncisscs with micaceous gneibsc\ and agmatites (500 m) pink felsic gneiss and agmatites (1,800 m) felsic gneiss (300 m ) three sequences of micaceous gneiss with thin biotite rich layers (400 m) micaceous handcd gneisses (550 m) felsic gneisses with basic paleosomes (1som) dark biotitc gneisscs (150m) micaceous gneisses (80 m) dark biotite gneisses felsic gneisses (150 m) plagioclase (an1523 with normal zoning) (tables 2 and 3). the most biotite rich gneisses form thin layers and contain strongly pinitized cordierite and hercynite, both occurring as inclusions i n later andalusite. reddish brown biotite, with t i 0 2 contents up to 4.4wt%, is stable in most rocks; locally it displays symplectite texture with fibrous sillimanite (tables 2 and 3). garnet biotite clusters of cm size in a plagioclase matrix are often observed in the biotite rich gneisses. the cores of the clusters are composed of flaky, brown biotite (tioz approximately 1.5 wt%) and granular garnet. most garnet grains are strongly fragmented and are usually free from inclusions, but a few contain biotite and quartz inclusions. the garnet has a mg content which decreases, while the fe and mn contents increase from centre t o rim, suggesting a retrograde readjustment of geology of gjelsvikfjella and western miihlig-hofrnannfjella 103 table 2 . metamorphic mineral assemblages of the micaceous gneisses from gjelsvikfjella, jutulsessen metasupracrustals. sil ky and cord sp ga hb mus bi pl kf q z il rut bt5 x x x x x bt13 x x x x x x yo14 x x x x x yo58 x x x x x x y o e g x x x x x y 0 1 4 b x x x x x x x bt4 i x x x yo54 x x x yo133 x yos8b x x x x x x x x x x accessories: apatite, zircon, allanite, monazite and secondary sphene, cpidote, chlorite and sericite. muscovites (mus) listcd are large lepidohlastic flakes (not alteration prciducts). magnetite may exist and has not been discriminated from allanite. x x x x x x x x x x x x x x x x x x the rim composition. porphyroblasts of plagioclase and microcline augen are occasionally developed in the micaceous gneisses. myrmekitic plagioclase also occurs occasionally. sphene, apatite, zircon, graphite and monazite are the accessories. the most biotite rich rock, containing domains t d d r 3. keprcscntativc microprobe analyses of metamorphic minerals from t h c rocks of the jutulsesscn metasupracrustals. lociilitics of the samples i n fig. 2. ... y058b: garnct biotite gneiss, grjotlia garnet biotite sp core rim core flaky pscudm. i n ga sio: tio? a1201 c r ? 0 3 fco* mno ( ' a 0 na10 k?o zno total mgo 38 32 36 89 0 0 u. 14 0.06 32.29 35.26 1.20 2.51 6.12 3.60 1.20 0.92 0 0 0 0 21.56 21.06 35.62 3.29 18.75 0.06 18.68 0 . 0 5 11.41 0 0.28 9.04 97.18 35.41 3.20 18.75 0.12 18.40 0.04 1 i .26 0 0.21 8.83 96.22 34.62 2.71 19.56 0.03 17.33 0 11.14 0 9.05 94.69 0.25 kation ratio 0 12 12 22 22 22 si 2.999 2.970 5.2y1 5.301 5.251 ti 0 0 0.367 0.360 0.309 a l 1.988 1.998 2.709" 2.6')9* 2.749* cr 0.009 0.004 0.007 0.014 0.004 fc 2.113 2.374 2.320 2.303 2.198 mn 0.080 0.171 o.no6 0.00s 0 mg 0.714 0.432 2.526 2.513 2.519 ca 0.101 0.079 ( i 0 0 n a 0 0 0.081 0.061 0.074 k 0 0 1.713 1.686 1.751 zn 0.573 * * 0.609" * 0.748** ~ x m g 0.253 0.154 0.521 0.522 0.534 feo* = total fe as feo, al* = all", a l * * = ai"', xmg = mg/mg + fe in all analyses. feldspars single separated grains in the matrix, unless specified. pl:an=27.9,ab=71.3,or=0.9andan=26.1,ab=73.5,or=0.4 0.02 0.09 59.70 0.19 34.31 0.18 4.16 1.37 100.02 4 0.001 0.002 i.on2 0.004 0.808 0.004 0.004 0.175 0.028 0.178 104 y . ohta, b . 0. t@rudbakken & k . shiraishi table 3 . (continued) garnet core rim y014: garnet biotite gneiss, sw of stabben matrix biotite flaky' in ga s i 0 2 t i 0 2 a1203 c r 2 0 3 feo' mno cao n a 2 0 k20 total mgo 37.40 0.01 20.82 0 32.56 2.53 3.81 2.29 0 0 99.42 36.36 0 20.56 0 33.38 6.34 2.22 1.30 0 0 100.16 kation ratio 0 12 12 si 3.009 2.967 ti 0.001 0 a1 1.975 1.977 cr fe mn ca na k mg xme 0 2.191 0.172 0.457 0.197 0 0 0.173 0 2.278 0.438 0.270 0.114 0 0 0.106 34.39 3.10 16.61 0.07 21.57 0.27 9.12 0.02 0.06 9.34 94.55 22 5.374 0.364 2.626* 0.433** 0.009 2.819 0.036 2.125 0.003 0.018 1.862 0.430 35.29 1.78 17.09 0.05 21.41 0.12 9.68 0.01 0.05 9.45 94.93 22 5.465 0.207 2.535* 0.5x5"* 0,006 2.773 0.016 2.235 0.002 0.015 1.867 0.446 33.72 0.61 21.80 0.17 19.71 0.25 8.25 0.01 0.05 8.31 92.88 22 5.244 0.01 1 2.756* 1.240** 0.021 2.564 0.033 1.913 0.002 0.015 1.649 0.427 fcldspars pl: an = 23.3, ah = 75.1, or = 1.6 and an = 15.8, ab = 82.9, or = 1.4 flaky': very thin biotite flake near garnet yoeg: garnet biotite gneiss, medmulen garnet biotite core rim* rim** coarse small' s i 0 2 38.48 ti02 0.04 a1203 21.43 ( 3 2 0 3 0.01 feo* 25.92 mno 0.57 mgo 6.13 cao 7.11 n a 2 0 0 k 2 0 0 total 99.69 kation ratio 0 12 si 3.002 ti 0.002 a1 1.970 cr 0.001 fe 1.691 m n 0.038 37.35 0 20.30 0.04 31.48 1.90 2.23 5.37 0 0 98.67 12 3.036 0 1.944 0.003 2.140 0.131 38.51 0 21.72 0.05 26.79 0.43 7.06 4.66 0 0 99.22 12 3.005 0 1.998 0,003 1.748 0.028 34.59 4.20 15.42 0 24.15 0.07 8.42 0.02 0.01 8.99 95.87 22 5.384 0.492 2.616* 0.213'* 0 3.144 0.009 35.54 2.86 15.72 0.23 22.59 0.07 9.09 0.11 0.04 8.73 94.98 22 5.519 0.334 2 481' 0.396** 0.028 2.934 0.009 geology of gjelsuikfjella and western muhlig-hofmannfjella 105 table 3 . (continued) ca 0.594 0 468 na 0 0 k 0 0 mg n.713 0.271) xmg 0.297 0.112 0.821 1.954 2 104 0 0.003 0.012 0 1.785 1.729 0.320 0.383 0.418 0.390 0.003 0.018 rim' = adjaccnt to plagioclasc rim" = adjaccnt to sillimanitc small': thin biotite flake around garnet feldspars pi pi pl pi kf an 44.3 40.4 46.3 50.8 0.3 ah 54.8 59 .0 53.2 48.6 0.5 or 0.9 0.6 0.5 0.6 99.2 a kyanite grain occurs as inclusion in thc garnct opx biotite bt16: granulitic gneiss, n e stabbcn h o r n b cumming. siol 50.86 tiol 0.05 a120, 0.54 cr203 0 feo* 27.62 mno 0.65 mgo 19.60 cao 0.35 na,o 0.02 k 2 0 0 total 99.6') kation ratio 0 6 si 1.956 ti 0.001 al 0.1)24* 0 cr i) fc 0.888 mn 0.02 1 mg 1.124 ca 0.014 n a 0.001 k 0 xme 0.559 feldspars 36.81 4.49 14.35 0.02 17.56 0.04 p3.46 0.04 0.21 x .90 95.88 22 5.529 0.507 2.471* o.o69** 0.002 2.206 0.005 3.014 0.006 o.061 1.705 0.577 pl: an = 48.3, ah = 51.2. o r = 0 . 5 and an = 41.5, ah = 58.1, o r = 0.4 48.73 1.00 6.63 0.04 13.77 0.20 14.88 10.79 0.99 0.34 97.37 23 7.123 0.110 0.877" o.2hb* * 0.005 1.683 0.025 3.243 1 .6yo 0.281 0.063 0.658 54.28 0.03 0.39 n 22.90 0.53 18.44 0.70 0.07 0 97.34 23 7.942 0.003 0.058* 0.009 * .* 0 2.802 0.066 4.022 0 . l l o 0.020 0 0.589 garnct corc rim bt24: amphibole gneirs, e jutulratcr o p x cpx biot , hornbl. cumming s o l 39.79 36.61 48.75 49.58 36.29 43.09 51.37 t i 0 2 0.13 0.02 0.04 0.12 3.66 1.61 0.02 a1203 21.25 20.76 0.44 0.74 14.78 9.42 0.33 mno 1.12 2.32 1 . o y 0.39 0 0.27 0.83 c r k h 0.01 0 0.01 0.02 0 0 0.03 feo* 25.73 30.14 37.32 15.66 19.21 21.13 30.58 106 y . ohta, b . 0. torudbakken d k . shiraishi table 3 . (continued) mgo 4.10 c d 0 9.20 nazo k2o total 99.33 kation ratio 0 12 si 2.988 ti 0.008 al 1.y80 cr 0.001 fc 1.701 m n 0.075 mg 0.483 ca 0.779 na k xmg 0.221 feldspars pi' 2.23 6.57 98.65 12 2.979 0.001 1.991 0 2.051 0.160 0.270 0.573 0.1 i 7 pi2 10.84 0.84 0 0 99.33 6 1.982 0.001 0.018* 0.004** 0 t 269 0.038 0.657 0.037 0 0 0.341 pi3 8.90 21.12 0.20 0 96.73 6 1.981 0.004 0.019* 0.016** 0.001 0.523 0.013 0.530 0.904 0.015 0 0.503 11.05 0.07 0.01 9.24 94.31 22 5.594 0.424 2.406' 0.279** 0 2.476 0 2.539 0.012 0.003 1.817 0.506 7.81 11.49 10.65 0.82 1.51 0.02 0.67 0 96.16 95.49 23 23 6.692 8.000 0.188 0.002 1.308* 0* 0.416** 0.060** 0 0.004 2,744 3.983 0.036 0 109 1.808 2.668 1.772 0.137 0.455 0.006 0.133 0 0.397 0.401 an 48.1 44.7 52.4 ah 51.0 54.4 46.9 or 1.0 0.9 0.7 pl': core, pi2: rim, pi': adjacent to garnet. ga-pl and hb-pl symplectites occur locally. with and without quartz, occurs as restite in a migmatitic gneiss (tables 2 and 3). in the quartz bearing domains garnet porphyroblasts are converted into a biotite, plagioclase assemblage. biotite, rutile, ilmenite and hercynite (mg/ fe + mg = 0.22, zno = 0.6 wt%) also occur as inclusions i n garnet. the mg/fe + mg ratios of the central parts of the garnet are as high as 0.28, whereas that of the biotite, which is constant and independent of the texture and assemblages, is 0.50-0.53. biotite inclusions in the garnet have slightly higher ratios of about 0.55. plagioclase compositions in the matrix are an14 to an17. in the quartz-free domains aggregates of sillimanite, hercynite (mg/fe + mg = 0.15-0.19, zno = 1.4 wt %), plagioclase (an23-27), biotite and small amounts of muscovite, chlorite, rutile, ilmenite and secondary kaolinite are found. her cynite is also found as scattered inclusions in large biotite flakes. andalusite occurs as porphyro blasts, surrounded by hercynite-plagioclase aggregates. these are overgrown by biotite which is chloritized along the margins. sillimanite is partly converted to muscovite. the described tex tural relationships of andalusite and sillimanite may indicate a late temperature increase under relatively low pressure conditions. the felsic gneisses contain less than 5% dark brown lepidoblastic biotite in a granoblastic matrix consisting of microcline, plagioclase and quartz. plagioclase grains sometimes have albite rims and myrmekitic texture. small amounts of pink garnet occur in some aplitic gneisses. an isolated small grain of orthopyroxene has been found in a felsic gneiss, coexisting with anti perthitic plagioclase. the basic rocks always occur as blocky paleo somes in the felsic and banded biotite gneisses and such agmatitic gneisses form distinct layers of some tens of metres in thickness. the basic rocks show varying degrees of disruption, ranging from conformable lenses to torn apart dykes or sheets, indicating their emplacements at different stages of the tectonothermal history. their tex tures also vary, ranging from completely recrys tallized granoblastic amphibole gneiss to weakly recrystallized igneous fabrics. the granoblastic amphibolitic gneisses consist of alternating bands of hornblende-biotite-plagioclase and clinopy roxene-plagioclase-quartz (tables 3 and 4). some bands have abundant garnet porphyroblasts in polygonal plagioclase domains. the compo sitional profile of the garnet shows that the mg/ fe + mg ratio decreases towards the margins geology of gjelsvikfjella and western miihlig-hofmannfjella 107 (fig. 3a). brown hornblende is replaced by green amphibole around its margins and orthopyroxene is converted to cummingtonite, which coexists with the green hornblende (tables 3 and 4). sub angular basic paleosomes commonly consist dom inantly of prismatic hornblende which often includes clinopyroxene grains. most hornblende, however, displays a coarse-grained lepidoblastic texture which is associated with plagioclase of andesine-oligoclase composition, and is over grown by biotite. one basic paleosome displays garnet-plagioclase clusters, whilst some garnet porphyroblasts are partly overgrown by a hornblende-clinopyroxene-plagioclase mosaic. brownish green hornblende of this rock has both orthoand clinopyroxene inclusions. b) middle succession above the layer parallel shear fault about 2,600 m of the middle succession are exposed. the lower 700 rn dominantly consist of felsic gneisses, but include three layers, 50-150111 thick, of fine grained, garnet-bearing, micaceous gneisses. some mica rich layers are fine-grained and schistose, whilst others have feldspar por phyroblasts. the middle 1,800 m are dominated by pink felsic gneisses, often granitic i n composition. sev eral layers of agmatite, including basic and biotite rich paleosomes, occur concordantly in the , i table 4. metamorphic mineral assemblages of the amphibolites from the jutulsessen metasupracrustals. yo18 yo9 bt17 y 060 btlo b'i2.4 yo60 yo92 bt24 includes garnet and cummingtonite. accessories: apatite, zircon, allanite and secondary epidote, zoisite, muscovite, chlorite, sphcne. bt16 (table 3) has a similar assemblage to yo42 and secondary cummingtonite surrounding hornblende. ( ): almost totally converted into hornblende and possibly plagioclase. opx cpx hb hi pl kf qz il x x x x x x x x x x x x x x x x x x x x x x x x x x (4 x x x x x (x) x x x x x x x x x x x x gneisses. the basic paleosomes are aligned in some places, and indicate that the original trend of the dykes was oblique to the gneissosity, while others are concordant lenses. the upper 500 m of the middle succession con tain two layers of banded biotite gneisses and several thin agmatitic layers in felsic gneisses. these rocks form the western ridge of grjotlia, and extend along the southern ridge of jutuls essen. the felsic gneisses in the upper part of the middle succession have a more granitic com position than those described in the lower part. the matrix is microcline rich and plagioclase mg/mg+fe 0.16 1 0.1 l 0.12 , 1mm , 0.8 1 1 0.l l m m i i 0.3 fig. 3 . compositional profiles of garnets: a) from a garnet amphiholite (bt24. ref. tables 3 and 4 ) , eastern part of jutulsessen; b) from a garnet biotitc gneiss (ref. tdbks 2 and 3 ) . northern medmulcn, castcrn gjclsvikfjclla. 108 grains, mainly oligoclase, are commonly myr mekitic. biotite, which is the only major mafic constituent, shows signs of chloritization around the margins. disruption and rotation of basic and biotite rich paleosomes and modal increase of microcline may indicate that parts of the felsic gneisses were mobilized in this area. y . ohta, b . 0. tgrudbakken & k . shiraishi c) upper succession the upper succession, which is more than 700 m in thickness, is dominated by felsic-granitic gneisses. the succession extends from the western ridge of grjotlia to jutulhogget to the east, where it forms a cliff approximately 500 m high. the micaceous and agmatitic layers are rare, and become more felsic, shadow-like discontinuous lenses. the fel sic gneisses laterally change into granitic mig matites of various textures, and increase in thickness towards the north. some basic paleo somes are enriched in biotite, and display ptyg matic folds. the upper gneisses extend to brugda where the thickness is estimated to be more than 500 m. various migmatites are present in brugda and in the eastern side of jutulsessen, and these rocks are similar to the risemedet migmatites. garnet-biotite gneisses and agmatites with basic paleosomes make up the middle part of the eastern slope of armlenet. these rocks are interlayered with granitic lenses, and have a thick ness of about 700m. stabben, a distinct tower in northeastern jutulsessen, is composed of a relatively homogeneous, coarse-grained granite with sharp contacts to the gneisses and migma tites. aplites in this area often contain small grains of red garnet. some garnet-biotite gneisses have small prismatic sillimanite. felsic gneisses occur in western armlenet and northern stabben, whilst the area south of stab ben is dominated by various migmatites. in west ern armlenet the succession consists of an approximately 500 m thick unit of felsic gneiss, interbedded by numerous agmatite layers and overlain by a garnet-biotite gneiss of 100 m thick ness and a 200 m thick felsic gneiss. the basic paleosomes are enriched by hornblende and con verted into small hornblendite bodies some tens of cm in size. an alternation of plagioclase por phyroblastic biotite gneiss and granitic gneiss occurs between the two peaks of stabben. these rocks laterally grade into agmatitic and shadow like migmatites northeast of stabben. a biotite rich gneiss from northeastern stabben has granoblastic orthoand clinopyroxene with reddish biotite. antiperthitic plagioclase and partly mesoperthitic orthoclase are common in this rock. a basic paleosome in the same area has granular clinopyroxene and ortho-pyroxene biotite aggregates in a complex symplectite texture. plagioclase shows irregular com positional domains in each grain. pale green, poi kiloblastic hornblende includes clinopyroxene grains, and is partly converted into cummingtonite during a retrograde process. the rabben nunataks 10km north of jut ulsessen are composed of coarse-grained, biotite and hornblende gneisses, each 20-30 m thick. dark, biotite rich boudins represent an older basic rock, whereas fine-grained schistose amphibolite is younger. a 7 m wide metagabbro dyke cuts the gneisses. a 100 m thick, regularly banded biotite gneiss occurs in the southern part of rabben. a separated small nunatak to the south consists of granitic gneiss. granitic gneiss with thin layers of garnet-biotite gneiss and agmatite with basic paleosomes are present to the east in medmulen, medhovden and gygra-risen at the northeastern edge of gjelsvikfjella. some biotite rich paleosomes in this area have large poikiloblastic garnets with inclusions of kyanite, ilmenite, rutile, potash feld spar and plagioclase (an51). a compositional profile of the garnet shows a convex shape for mg with a decrease near the margins (fig. 3b). sillimanite rarely occurs in contact with garnet and plagioclase in the matrix. d) original rocks of the jutulsessen metasupracrustals complex deformation and metamorphic recrys tallization make estimation of protolith rocks dif ficult and uncertain. however, the occurrence of al-silicates, cordierite and garnet in dark micaceous layers may suggest originally argil laceous to sandy sediments. a possibility of acid volcanic rock origin for the felsic gneisses cannot be ruled out. basic rocks probably originated from both synand late-tectonic basic dykes and sheets. e) metamorphic conditions the metamorphic mineral assemblage in the pel itic gneisses commonly includes biotite and geology of gjelsuikfjella and western muhlig-hofmannjjella 109 garnet. sillimanite has been found to b e a major constituent in some rocks (tables 2, 3 and 4). occurrence of kyanite as inclusions in garnet (tables 2 and 3, sample y o e g ) indicates an intermediate pressure facies series for the pro grade process. orthopyroxene occurs in some silica undersaturated rocks, suggesting the maxi mum metamorphic grade is transitional from upper amphibolite facies t o granulite facies. cordierite and hercynite in some rocks may reveal a pressure fall after the metamorphic climax. andalusite porphyroblasts found in a silica undersaturated gneiss a r e replacing an older gar net-biotite assemblage, and are overgrown by sillimanite and biotite. t h e sillimanite is partly converted into muscovite. these reactions reveal a high temperature facies metamorphism fol lowing a cooling period after the older meta morphism, which is probably related to a thermal event during the emplacement of large masses of charnockite, which will be described later. for the calculation of the maximum meta morphic conditions, geothermometry and geo barometry were applied. normally, garnet has a high content of c a and mn and biotite has dis tinctive amounts of ti. therefore, garnet-biotite geothermometry is not applicable for most rocks. however, a central part of the garnet and its inclusion biotite from a gneiss of grjotlia gave a temperature range of 650-750°c by the cali bration given by thompson (1976). the garnet rutile-sillimanite-ilmenite ( g r a i l ) geobarome t e r (bohlen e t al. 1983) for the same rock gave 8 * 1 kb at -760°c. rocks from sverdrupfjella to the west of gjelsvikfjella were examined for comparison, using the samples collected by iijelle in 197cl-71. in this area orthopyroxene has not been found in intermediate and basic rocks, suggesting that the metamorphic grade did not reach granulite facies. a garnet porphyroblast has sillimanite and quartz inclusions, and indicates upper amphibolite facies. garnet-biotite geothermometry (thomp son 1976) gave 750°c for t h e central part of the garnet, t h e geobaronietry of newton & haselton (1981) yielded about 7 k b at -750°c and g r a i l gave 8 k b at -750°c for a garnet and its inclusion biotite. these calculations and the lack of ortho pyroxene show a transition from upper amphibo lite facies t o granulite facies, which is similar to that of t h e rocks of gjelsvikfjella. these results a r e somewhat higher than those obtained by grantham e t al. (1988): 560-690°c and 5-6 kb for the main metamorphism in northern h . u . sverdrupfjella. an ultramafic rock sampled in this area shows late magmatic conditions of 850°c and 9-10 kb. t h e metamorphic conditions cal culated for the rocks in the areas from kir wanveggen t o middle miihlig-hofmannfjella are summarized in fig. 4. risemedet migmatites this migmatite complex is defined as a lithologic unit. t h e jutulsessen metasupracrustals show gra dational transition t o t h e risemedet migmatites in the south. banding in biotite gneisses gradually disappears and biotite is concentrated in thin seams in granitic-aplitic rocks. t h e latter contain microcline and plagioclase. plagioclase has albite rims and well developed myrmekite texture. t h e thick felsic gneisses around jutulhogget show a very faint gneissosity of irregular orientation and basic dykes show strong ptygmatic folds and rotated fragments, indicating mobilization of the felsic gneisses. t h e gneisses in the middle part o f the eastern slope of armlenet have agmatitic and shadow-like paleosomes in a medium-grained granitic gneiss. gneissosity is locally difficult to detect. similar migmatites occur in the eastern side of stabben. t h e basic paleosomes in t h e gneisses change into more biotite enriched conformable layers, having distinct amounts of microcline and quartz. some basic rocks in armlenet cut the gneissosity of both gneiss paleosomes and granitic metatect and include angular blocks of granite. the basic rocks themselves a r e cut by aplite and pegmatite dykes. migmatites with streaky, shadow-like and biotite rich paleosomes occupy the risemedet and horten areas. similar rocks are probably also present in medhovden based on distant observation. t h e modal content of hornblende is exceeded by biotite in the basic paleosomes. orthoclase perthites are often present in both gneissic and basic paleosomes. t h e gneissic paleosomes lose their clear sharp boundaries t o the granitic metatect, and gradually transform into homogeneous granitic rock. migmatite varieties also make up most of terningskarvet. biotite gneiss-rich layers, about 100 m thick, and granitic migmatite a r e mappable units in t h e area. t h e biotite gneiss is often feldspar porphyroblastic and strongly folded, and contains many basic paleosomes. a massive 110 y . ohta, b . 0. t#rudbakken & k . shiraishi kb 10 8 6 4 1 mh: muhlig hofmannfj. g : gjelsvikfj. sn: north sverdrupfj. ss: south sw: west k: kirwanryggen #:: ahimannryggenkrgmassivet i amph.fj i i a ’ h i i i . 600 700 8 00 9oooc fig. 4. pressure-temperature conditions of the metamorphic rocks from western dronning maud land. ahlmannryggen borgmassivet: wolmarans & kent (1982); kirwanveggen and h. u . sverdrupfjella: wolmarans & kent (1982), grantham et al. (1988), allen (1990); gjelsvikfjella and miihlig-hofmannfjella: present study. reference curves: 1. holdaway (1971), 2 . ringwood & green (1966). 3 . richardson (1968), 4. percival (1983), 5. holdaway & lee (1977). broken curves: estimated retrograde conditions. diorite, about 200 m wide, occurs concordantly in the granitic migmatites in the southwestern part of terningskarvet. a plagioclase porphyroblastic biotite schist occurs in the same area, alternating with garnet bearing aplite layers and schistose amphibolites. these rocks form a km wide, large paleosome in the migmatites. the granitic metatects are rich in pink coloured microcline, and contain as much as 5% biotite. the basic paleosomes have clino pyroxene inclusions in hornblende grains and biotite overgrows on the hornblende. medium grained oligoclase is the main constituent and no hydration of mafic minerals has been observed. gneisses and granitic layers, some tens to a few hundred metres thick, were traced by binocular observation on nupskammen, von essenskarvet and the southwestern side of jutulsessen, and the observed outlines are shown in fig. 2. geological structures of gjelsvikfjella a) mesoscopic structures all rocks of the jutulsessen metasupracrustals show distinct gneissosity represented by dif ferentiated layering and preferred orientation of mafic minerals. the gneissosity is considered to be the result of the main period of deformation and metamorphism. the observed orientation of the foliation is summarized on the equal-area lower hemisphere stereographic projection for six subareas in gjelsvikfjella (fig. 5). some layers, cm to dm thick, include isolated isoclinal folds, indicating that the gneissosity is a transpositional foliation. compositionally distinct units, some hundreds of metres thick and with 5 10 km lateral persistency, can be considered to reflect differences in primary lithologies to some extent. some granoblastic basic rocks are com geology of gjelsvikfjella and western miihlig-hofmannfjella 111 fig. 5 . stereographic projections, lower hemisphere, of foliations and lincations from gjclsvikfjclla. division of the wharca\ and general structures are shown i n the inserted map. ( ): number of measured foliation poles; 1-5-10: pcrccntagc of thc contours for the foliation plots; solid dot: mineral lineation; opcn circle: fold axis. pletely conformable with the gneissosity of sur rounding rocks. these are believed to represent pre-metamorphic basic sheets or dykes. basic rocks with clinopyroxene in hornblende show oblique alignment t o the gneissosity, and are interpreted as syn-metamorphic intrusions. the isoclinal folds are refolded by later tight folds which represent the main phase of deform ation (d2). the isoclinal folds therefore indicate a strong deformation, d,, prior to the main recrystallisation phase dz. the most common mesoscopic fold axes coincide with the mineral lineations defined by preferred orientation of mafic constituents. these are formed during the main deformation-meta morphism, d2, together with the formation of gneissosity and differentiated layering. these mesoscopic linear structures have by later deform ation (d3) been rotated into a wide large girdle along the maximum gneissosity girdle in the type locality of the jutulsessen metasupracrustals in grjotlia (subarea i1 in fig. 5). similar rotations of the lineations are seen in the diagrams for subareas 111 and vi, but the axes of rotation are oblique to the axes defined by the gneissosity girdles. the d3 deformation resulted in a kind of dome-basin structure, as shown by the general trends of gneissosity in the inserted map of fig. 5. the wide girdle deviations of lineation in sub areas i, 11, i11 and iv can be explained by the rotation during the d3 migmatization. b) faults a distinct fault, the armlenet fault, occurs in northern armlenet (fig. 2 ) . it has an e-w strike, subvertical dip and a downthrow to the south. the fault plane itself is not directly exposed, but appears to be manifested by a narrow discrete break buried beneath a 10 m wide zone of scree cover. the northern side of the fault forms a 150 m high vertical cliff, with two types of basic dykes present. one type is a disrupted and folded biotite amphibolite which was possibly emplaced during the migmatization. the second type con sists of a network of unmetamorphosed dolerite of possible mesozoic age. from the dip change of the gneissosity across the fault it is considered that the fault intersects the crest of a regional antiform. the eastern extension of the fault prob ably passes between medmulen-medhovden and gygra-risen and the gneissosity in these two 112 y . ohta, b . 0. torudbakken & k . shiraishi areas also shows opposing dips. t h e occurrence of many basic dykes along t h e fault and its structural relationship t o the major regional structures sug gest that this fault may have been initiated during the late stages of the d2 deformation episode, and was subsequently reactivated during the mesozoic. a ne-sw striking fault, dipping 60" eastwards, occurs about 2 km south of the armlenet fault (fig. 2), and cuts strongly migmatized gneisses. this fault separates an easterly dipping western block from a westerly dipping eastern one, but its strike is oblique t o that of the gneissosity. this fault may b e a splay fault of the armlenet fault. a 3-5 m wide shear zone was observed in the middle part of t h e eastern ridge of grjotlia (fig. 2). cataclastic structures a r e developed, but no associated retrograde metamorphism has been identified. this fault is nearly parallel to the com positional layering in the biotite rich gneisses and the sense of displacement is unknown. c) fold structures there is n o structural discordance between the jutulsessen metasupracrustals and the risemedet migmatites, and their gneissosities define an oval, incomplete d o m e structure, the jutulsessen dome, with its axis elongated in a nw-se direc tion (subareas 11, i11 and iv). t h e armlenet fault cuts t h e northern part of the dome. north of the fault t h e gneiss-migmatites form a steep northeast trending fold (subarea i ) . t h e gneissosities in the medmulen-medhovden area have roughly e-w strikes and moderate southern dips, while those of t h e gygra-risen area have northern dips. this may show an open anticline with an e w trend between the two areas. a n asymmetric, nw-se trending antiform occurs around t h e horten nunatak with 50"-60" sw dips in t h e western limb and 60"-75" n e dips in the eastern limb. t h e eastern limb of this fold can be followed into a synform t o t h e east of horten, where t h e opposite flank dips about 10" 15" to t h e west. these structures have not been observed on t h e northern cliffs of medmulen medhovden which lie in t h e strike direction of the folds. t h e antiform is therefore probably terminated in risemedet as an elongate dome. a small open synform with a nw-se trend and a southeasterly plunging axis occurs in the southeastern part of brugda. this synform is a subordinate structure on the southern slope of the jutulsessen dome. a major s e plunging synform occurring in terningskarvet is divided in two by a small anti form around t h e highest part of the nunataks. t h e axes of these folds plunge t o the se, subparallel to those in brugda and horten. compositional layers include many isoclinal folds indicating that they a r e of d1 structure. t h e folds described above are from t h e d2 deformation, with some later rotation by the d3 deformation. geological event history in gjelsvikfjellu t h e following successive events can be recognized from t h e petrographic and structural observa tions: 1) argillaceous and sandy sedimentary rocks may b e protoliths for the dark micaceous gneisses occurring in t h e jutulsessen metasupracrustals. felsic gneisses may alternatively have been derived from acidic volcanic rocks. w e cannot exclude that it is possible t o discriminate between some plutonic rocks in the metasupracrustals. 2) strong deformation resulted in the for mation of isoclinal and tight folds and trans positional foliation (d1 and dz phases of deformation). t h e deformation phases were associated with major metamorphism under upper amphibolite to granulite facies conditions. increasing temperature or phz0 led to regional migmatite formation especially in the southern areas. 3) regional open fold structures (d,) refolded the earlier folds into dome-basin-like structures. metagabbro intrusions a r e associated with the d3 deformation phase and the emplacement of basic, aplitic and pegmatitic dykes took place in the later stages of this phase. 4) brittle activation of the armlenet fault. 5 ) emplacement of the mesozoic dolerite dykes associated with brittle deformation reac tivation of the armlenet fault. western muhlig-hofrnannfjellu o u r mapping covered t h e area from skigarden (4"30'e) t o ahlstadhottane (s"30'e) along the northern escarpments of western miihlig-hof mannfjella. reconnaissance observations were made t o the south (fig. 6). t h e svarthamaren charnockites and the snotoa metamorphic complex dominate in the area. the former intrude into t h e latter. t h e term char geology of gjelsvikfjella and western muhlig-hofmannfjella 113 114 y . ohta, b . 0. tgrudbakken & k . shiraishi nockite is used for rocks with orthopyroxene and mesoperthite as essential constituents, which have a dark brownish-green colour due to the felsic constituents. some varieties have biotite and hornblende as main minerals. the charnockite intrusion will be described from west to east. skigarden-snbtoa area and the area to the west the skigarden and b j ~ r n s a k s a nunataks are mainly composed of coarse-grained, dark char nockite (fig. 6). the rocks have large idiomorphic crystals of orthoclase mesoperthite, a large modal content of biotite and both orthoand clino pyroxene are present. plagioclase grains are often antiperthitic. isolated pale coloured blocks, up to 50m across, mainly of heterogeneous granitic com position, often with gneissic and basic paleo somes, are included in the charnockite mass. size and frequency of the granitic xenoliths increase to the south. a one km wide, vertically dipping xenolith rich zone of charnockite occurs in southern skigarden. the zone has a roughly e w strike, and forms the boundary to the shadow like migmatites of snatoa (fig. 7). small gneiss and granite blocks have diffuse margins and the adjacent charnockite shows a red coloured contact zone, cm t o dm wide, probably formed by assimilation. the migrnatites of sncbtoa. commonly with shadow-like and streaky paleosomes and some times agmatitic, have an e-w strike, dip mod erately to the south and display upper amphibolite facies mineral assemblages (table 5 ) . parts of the sncbtoa migmatites form a sheet about 500 m thick in the charnockite. a similar sheet-shaped occurrence of char nockite and migmatites was observed in the north ern cliff of tjuvholene, northern gryt~yrfjellet. in these mountains dark granulitic rocks contain sheets of granitic rocks with relatively sharp con tacts. grinda nunataks to the north of tjuvholene consist entirely of charnockite. a zone from southern skigarden to western grytcbyrfjellet can be regarded as an intrusive transition zone between a large charnockite mass t o the north and metamorphic rocks to the south. fig. 7. contrasting mountain shapes between the charnockite (pinnacles) and the snotoa metamorphic complex (massive mountains); skigarden i n front and sncdtoa in the background. geology of gjelsvikfjella and western muhlig-hofmannfjella 115 table 5. metamorphic mineral assemblages of the gneisses and migmatites of the sndtoa metamorphic complex. sil ga sp co opx cpx hb bi pl kf qz il bt80 bt79 bt58 bt97 bt95 bt108 bt120 bt104 bt94 bt85 x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x accessories: apatite, zircon, allanite, monazite and secondary epidote, sphene, serpentine, chlorite, vermiculite, hematite. sample yo169 (table 6) has the same assemblage as sample bt95. sample yo167 (table 6) has the same assemblage as bt97, but the content of opx is very small. west of flogeken a dark charnockite, more than one km wide, occurs t o the south of hoggestabben (fig. 6), and has e-w strikes and steep dips. hoggestabben consists of a granitic migmatite with banded gneiss relics. weakly banded granulitic rocks dominate in hochlinfjellet. distinct banded gneisses, a few km wide, occur in the northern part of vedskllen. a 15 m thick skarn layer has been observed in its eastern part. towards the western part of vedskdlen the banded gneiss is replaced laterally by a granulitic granite . festninga further to the west (fig. 6) is dom inated by granitic migmatites with some distinct layers of banded gneisses and agmatites. these rocks have a roughly e-w strike and gentle to moderate southward dips. the banded gneiss migmatites in festninga and bvrevollen are prob ably the continuation of the jutulsessen meta supracrustals and the risemedet migmatites of eastern gjelsvikfjella. petrellfjellet and harnarskoruene areas petrellfjellet to the south of skigarden (fig. 6) has outcrops of granulitic metamorphic rocks along the northwestern foothills, on the northern ridge (with the 2,285m peak) and the eastern part. dark charnockite which makes up the north ern tip of the eastern ridge is a roughly concordant layer to the migmatites, and has a nearly e-w strike and 20°-40' southward dips. another char nockite in southern petrellfjellet overlies the metamorphic rocks. hamar@ya and a nunatak to the south are composed of massive charnockite. granulitic migmatites with some banded gneiss and agmatite layers with e-w to ene-wsw strikes and 10'40" southward dips occupy slok stallen and kvithamaren (fig. 6). these rocks were also observed in hamarskorvene to the southeast, where the banded gneisses consisted of pink feldspar porphyroblastic biotite-garnet gneiss, felsic gneiss, agmatitic migmatite with basic paleosomes and pink aplitic gneiss layers. some of the pink gneisses are augen gneiss and mylonite gneiss. ptygmatic folds are frequently observed in the gneisses and migmatites. an approximately 5 m thick, coarse-grained marble layer, containing diopside-wollastonite-grossular aggregates, occurs in the gneisses. coarse-grained mosaic texture of subangular hornblende and plagioclase has been preserved in an agmatitic basic paleosome found in the agmatitic basic rocks. the rock consists of plagio clase, an 38-26, normally zoned, biotite, ortho and clinopyroxene and quartz with accessory ilmenite and apatite. randomly orientated, yel lowish brown biotite is dominant, and replaces orthopyroxene in places. irregularly shaped orthopyroxene with fine lamellae of clinopyroxene is decomposed into biotite-quartz aggre gates. this rock is considered to be a basic intrusion which was emplaced after the formation of the gneisses, but prior to the intrusion of charnockite. these banded granulitic rocks and upper amphibolite facies rocks seem to dominate in the southern part of western muhlig-hofmannfjella and are continuous with those of gjelsvikfjella. the charnockite extends eastwards from vestre skorvebreen. an isolated nunatak to the north, larsgaddane, is composed of homogeneous, coarse-grained pink granite, with large idiomorphic potash feld spar phenocrysts. this may be a large xenolith in the charnockite, granitized charnockite or poss ibly a younger intrusive. hamarskaftet the northern nunatak of hamarskaftet, 1,661 m high (fig. 6), consists of pink granite with small feldspathized gneissic paleosomes. the southern nunatak, 1,745 m high, is composed of dark char 116 nockite, while a small nunatak about 1.5 km t o the north consists of migmatite with shadow-like paleosomes including biotite gneiss blocks. t h e migmatites may b e part of a large xenolith in the charnockite. y . ohta, b . 0. t#rudbakken h k . shiraishi plogska ftet occurrences of gneiss-migmatite-granite xeno liths in charnockite a r e well demonstrated in these nunataks (figs. 6 and 8). t h e northernmost nun atak, 1,595 m high, is composed o f a streaky migmatite including tightly folded, biotite-horn blende gneiss. charnockite intrudes along joints in the gneiss, crosscutting the gneissosity. this gneiss mass may b e a large block enclosed in the charnockite. another type of xenolith which occurs in this nunatak is medium-grained granoblastic gneiss containing fe-rich minerals (tables 5 and 6). t h e rock consists of orthopyroxene, biotite, plagio clase, potash feldspar quartz and ilmenite. t h e orthopyroxene is a ferrosilite relatively rich in m n ( e n = 18.5, fs = 77.2, r h = 2.0, wo = 1.9) and the biotite is rich in feo and ti02 (28.65 and 4.85 wt%, respectively). plagioclase shows weak zonation from an32 t o an28. another granulitic rock sample of this xenolith type contains ortho and clinopyroxene, biotite, antiperthitic plagio clase, ilmenite and monazite. t h e orthopyroxene is broken down t o biotite and quartz around its margins. two-pyroxene geothermometry (wood & banno 1973) yields 780°c for this rock. t h e high-temperature mineral assemblages possibly resulted from re-equilibration d u e t o the thermal influence of t h e charnockite o n the original granu lite facies assemblages. t h e 1,623 m high nunatak reveals typical occur rences of charnockite dykes cutting migmatites of shadow-like, agmatitic and ptygmatic types. biotite rich and basic gneisses occur as numerous paleosomes in the migmatites, showing various degrees of granitization. homogeneous white granite is also found as xenoliths in the charnock ite. o n e biotite rich gneiss paleosome has a gar net-sillimanite assemblage. many aplite and pegmatite dykes cut the migmatites and numerous joints a r e filled by leucocratic veins. t h e char nockite cuts all rocks described above with sharp contacts. only a few, narrow white veins a r e injected along joints in t h e charnockite and these a r e probably t h e e n d products of the charnockite consolidation. a weak foliation is revealed by fig. 8. occurrencc of xenoliths of gneisscs and migmatitcs in the charnockitc. plogskaftct. the alignment of subidiomorphic potash feldspar crystals in the charnockite. t h e three middle nunataks, 1,731 m , 1,625 m and 1,755 m high, also show good examples of xenolithic occurrences of gneisses, migmatites and granite in the charnockite (fig. 8). many angular blocks, u p to 50 m across, are aligned in the charnockite along its gentle, west dipping weak foliation. even small xenoliths of some dm size have sharp angular outlines. charnockite dykes, cutting agmatitic migma tites, a r e exposed on the northern face of the 1,755 m high nunatak. both granitic metatect and gneissic paleosomes a r e sharply transected by white pegmatites and all these rocks are again cut by dark charnockitic dykes. along the margins of the charnockite fine-grained chilled facies, about 1 m in width, a r e locally developed. t h e southernmost nunatak consists of dark charnockite in its western half, whilst a homo geneous, white potash feldspar granite occurs in t h e eastern part. several dykes of charnockite cut geology of gjelsuikfjella and western muhlig-hofnzannfjella 117 table 6. representative microprobe analyses of thin-sections from the snqtoa mctarnorphic complex and the svarthamaren charnockite batholith (ref. tables 5 and 7). sample localities are shown in fig. 6. sio: tiol ai1o, c r 2 0 i fco^ m n o mgo c a 0 na:o k 1 o total kation ratio 0 si ti al cr fl. m n ('a nil k x m g mg bt104, charnockitc, hegsenga 01 cpx hornblende 19 .69 0 0 0.04 hx.hl 1 . x i 0.32 0 0 100.47 4 i .no0 1) 0 o.no1 1.932 0.052 0.016 0 0 0. ()ox ~ 4x. 22 0.03 0.97 0 2x. i x 0.02 0.93 20.47 0.25 99. (1 1 0 i .9xs 0.001 0 . 0 is* o.030'r 0 0.970 0.022 0.057 0.903 0.020 0.056 ~ 37.9s 0.97 11.64 0.03 32.25 0.26 0.56 10.46 i .68 1.41 97.22 23 6.246 0.121 i .754* 0.504* o.oo4 4.439 0.036 0 . 137 1 .x44 0.536 0.296 0 . 0 3 0 feo* =total fe as fco, al" = all". al** = ai"', xmg = mg/fe + mg i n a l l analyses. feldspars pl: core: an = 33.6, ah = 65.3, or = 1.1 rim: an = 29.9. ab = 69.3. or = 0.8 bt95: gneiss xenolith in charnockite, h ~ g s e n g a opx c p x hornbiendc grain lamell. poiki to opx biot $10, t i 0 , alzo, c r 2 0 3 feo* mno cdo n d @ k z o totdl mgo kation ratio 0 si ti al cr fe mn ca mg ~ 4x 59 0 09 0 23 0 02 40 23 1 5 1 x 53 0 82 0 0 100 02 6 1.993 0.003 0.007* 0.004** 0 001 1.380 0.052 0.522 0.036 50.00 0.06 0.58 19.57 0.63 7.46 20.40 0.23 0 99.03 0.10 6 1.9x2 0.002 0.018* 0.003 0.649 0.021 0.441 0.x67 n , on9 * * 50.01 0. i3 0.77 0.04 19.77 0.63 7.44 20.49 0.34 0 99.62 6 1.973 0.004 0.027% o.n09* * 0.001 0.652 0.021 0.438 0.866 42.91 8.34 0.03 21 45 0.32 8.76 10.97 1 .62 1.41 96.18 0.37 23 6.730 1.270* 0.272** 2.813 0.043 2.048 1.843 0.044 0.004 39.94 1.21 10.22 0.02 27.80 0.13 3.85 10.71 1 .66 1.63 97.17 23 6.423 0.146 1.577* 0.360** 0.003 3.739 0.923 1.845 0 . m 37.65 3.20 12.42 0.ox 20.34 0 1 l j ils7 0.02 9.18 94.72 0.07 22 5.81 1 0.371 2.189* 0.071 * * 0.010 2.626 0.025 2.662 0.003 118 y . ohta, b . 0. tfirudbakken & k . shiraishi table 6. (continued) na 0 0.018 0.026 k 0 0 0 xmg 0.274 0.405 0.402 feldspars pl: core: an = 32.6, ah = 65.2, or = 2.2 rim: an = 32.4, ah = 65.2, or = 2.4 poiki: poikiloblastic to opx: contact with orthopyroxene 0.493 0.282 0.421 0.518 0.334 0.198 0.021 1.808 0.503 y0167: gneissic xenolith i n charnockite. n plogskaftet opx biotite sioz t i 0 2 crzoi feo' mno cao n a 2 0 k 2 0 total , 4 1 2 0 3 mgo 47.22 0.03 0.32 0.07 43.69 1.12 6.00 0.82 0.05 0 99.32 34.yo 4.85 13 12 0 28 65 0.14 5.08 0.01 0 01 8.75 95 51 kation ratio 0 6 22 si 1.988 5.582 ti 0.001 0.583 a1 0.0121 2.418' cr 0.002 0 fe 1.539 3.832 mn 0.040 0.019 mg 0.377 1.211 ca 0.037 0.002 na 0.004 0.003 k 0 1.786 xmg 0.197 0.240 fcldspars pl: core: an = 30.4, ah = 68.3. or = 1.3 rim: an = 29.0, ah = 70.2, o r = 0.8 opx: en = 18.9, fs = 77.2, rh = 2.0, wo = 1.9 0.004** 0.056** y0169: gneissic xenolith in charnockite. n plogskaftet opx cpx biotite s i 0 2 tioz a1209 ( 3 2 0 3 feo* m n o cao nazo k2o total kation ratio 0 si ti mgo 49.33 0.11 0.34 0 33.53 1.20 13.85 0.81 0 0 99.17 6 1.973 0.003 51.07 0.11 0.64 0 14.44 0.5 i 10.66 21.09 0.29 0 98.81 6 1.981 0.003 36.66 5.05 13.17 0.08 19.62 0.16 10.84 0.06 0.05 9.20 94.89 22 5.641 0.584 geology of gjelsuikfjha and western muhlig-hofmunnfjella 119 table 6. (continued) al 0.016* 0.019* 0 0.010 cr 0 0 fe 1.122 0.468 mn 0.041 0.017 ca 0.035 0.876 n a 0 0.022 k 0 0 xmg 0.424 0.568 feldspars pl: an = 27.8. ab = 70.9, or = 1.2 and an = 26.9, ah = 71.9, or = 1.2 mg 0.826 0.616 2.359* 0.029 0.010 2.525 0.021 2.487 0.010 0.015 1.806 0.496 the granite and t h e contact is partly sheared with a 5-10 cm wide mylonite zone. fe-rich, medium grained charnockite from this area consists of fayalite (fa = 99), hedenbergite ( e n = 2.5, fs = 50.5, w o = 47), plagioclase (an35-26from centre t o rim), quartz, ilmenite and magne tite (tables 6 and 7). t h e quartz-fayalite-mag netite assemblage from this rock gave fo2 = 10-(’@15) bars and 750°c (wones & gilbert 1969) as the formation conditions for t h e charnockite. svarthamaren to ahlstadhottane t h e high mountains in this area are exclusively composed of charnockite (fig. 6). weak foliations a r e locally present and they generally show nw se strikes and moderate westward dips to the west of svarthamaren and eastward dips t o the east of bbsbolken. t h e charnockite can be divided into two facies: a ) a medium-grained, greenish grey rock with less than 10% mafic constituents (orthoand clino table 7. mincral assemblages of the svarthamaren charnockite, muhlig-hofmannfjclla. 01 opx cpx hh hi pl k f qz i l bt46 bt48 bt98 bt106 bt104 btll5 bt69 bt144 x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x accessoiies: apatite, zircon, allanitc. monazite and secondary cpidote, sphene, serpcntinc. pyroxene and locally biotite), b) a dark brown, coarse-grained rock, characterized by large idiomorphic potash feldspar crystals and smoky quartz. these two facies show sharp contacts. t h e medium-grained variety is restricted in its occur rence t o northern svarthamaren, southern cumu lusfjella and t h e middle part of hogsenga. large amounts of deep green hornblende is t h e major mafic constituent. orthoand clinopyroxene a r e always present and often included in the horn blende. pale coloured, irregular flame-like patches occur in the medium-grained charnockite with high angles t o the weak foliation (fig. 9). t h e flame-like patches d o not display clear lithological differences to t h e dark charnockite, except for t h e colour of the felsic constituents. t h e centres of some flame domains are granitic in composition. these flames may have formed by late hydration of the charnockite or by assimilation of granitic xenoliths in t h e charnockite. small gneissic, migmatitic and granitic xeno liths occurring elsewhere in the charnockite show varying degrees of assimilation, revealed by vari ous widths of t h e transition zone of the block margins. isolated large granitic xenoliths, tens t o hundreds of metres in size, are observed in the southeastern cliff of svarthamaren, t h e north western tip of b h b o l k e n , the middle part of the western cliff and northeastern slope of hogsenga, the southern and southeastern parts of cumu lusfjellet and t h e middle and eastern parts of ahlstadhottane. t h e 2,695 m peak of south western breplogen consists of granitic migmatites containing basic paleosomes and together they form a large xenolithic block in the charnockite. some xenoliths show diffuse margins of white tint, but many others have very sharp angular 120 y . ohta, b . 0. torudbakken & k . shiraishi fig. 9. flamc-likc. pale coloured facies in thc charnockitc, hsgsenga block boundaries. a gneissic xenolith in the char nockite of hogsenga consists of orthoand clinopyroxene, dark green hornblende, brown biotite, plagioclase, potash feldspar, quartz and accessory ilmenite (tables 6 and 7). ortho pyroxene with exsolved ca-clinopyroxene ( ferroaugite-ferrosalite) lamellae is surrounded by poikiloblastic hornblende. clinopyroxene also occurs as individual medium-sized grains in the rock and the composition is similar t o that of the lamellae. t h e hornblende is heterogeneous both in colour and composition within one grain. two pyroxene geothermometry (wood & banno 1973) gave a possible blocking temperature of about 795°c for this rock. distant observation by binoculars from ahlstadhottane and breplogen t o t h e mountains and nunataks t o t h e east of austre skorvebreen shows that all visible exposures are dark red coloured charnockite. dyke rocks several different types of dykes, which cut the medium-grained charnockite, are well exposed in a 300 rn high cliff in southern svarthamaren: 1) t h e oldest dykes a r e agmatitic and irregu larly shaped. they consist of biotite rich basic rock fragments of 1g-20 cm size, and occur in a fine-grained, dark yellow, felsic granulitic matrix. 2 ) yellowish felsic charnockite forms thin dykes, locally with pink-coloured seams in the centre. 3) a pink, impregnation-like aplitic rock forms irregular dykes. they cut t h e felsic charnockite dykes. 4) hornblende rich basic dykes with large, white idiomorphic potash feldspar cut t h e pink aplitic dykes. 5 ) d a r k coloured, basic dykes with biotite clus ters cut the feldspar idiomorphic dykes. these five types of dykes a r e considered to be emplaced during a late consolidation stage of the medium-grained charnockite. there a r e two more types of sharply cross cutting dykes: 6) dark metabasite dykes, 3-5 m thick, are the most distinct dykes in the upper part of the cliff. geology of gjelsuikfjella and western muhlig-hofmannfjella 121 they can b e followed in a distance of more than 3 k m with a gentle dip to the south. 7) grey aplite dykes cut t h e metabasite dykes, and sometimes form composite dykes with the latter. dyke types 6) and 7 ) d o not show any mobil ization, but they a r e moderately recrystallized. all dykes a r e cut by the coarse-grained, dark charnockite in the northern part of svarthamaren. svarthamaren is t h e only locality with such a high concentration of basic dykes in the medium grained charnockite, which indicates that the area may be in a special structural position near the margin of t h e charnockite massif. s u m m a r y o f the geology in western miihlig h o f m a n n f j e l h t h e observations in western miihlig hofmannfjella show that a large intrusive char nockite complex, the svarthamaren charnockite batholith, occurs in the northeastern part of the area. t h e main rock types a r e coarse-grained and medium-grained charnockite. a westward projection of the coarse-grained charnockite extends from svarthamaren to ski garden. this projection splits into several major subconcordant sheets and dykes and they cut into the snatoa metamorphic complex along the east e r n parts of grytoyrfjellet and northern hoch linfjellet. t h e coarse-grained charnockite has sharp cutting contact relationships t o t h e medium grained charnockite, showing that t h e coarse grained charnockite is younger than the former. t h e medium-grained charnockite includes a large proportion of xenoliths probably derived from the snotoa metamorphic complex. these xenoliths a r e assimilated t o a varying degree. however, many xenoliths, even small ones, are almost devoid of assimilation and have retained their angular outlines a t many localities. strongly assimilated rocks a r e mostly of granitic compo sition. partly assimilated gneissic and basic xeno liths commonly have white coloured margins in which t h e granulitic mineral assemblages are lost. white patches may also b e hydrated charnockite by volatiles derived from t h e xenoliths. t h e sn0toa metamorphic complex occupies the high mountains in t h e southern part of western miihlig-hofmannfjella. o n the western side of vestre skorvebreen t h e snotoa metamorphic complex contains granulite facies gneisses and migmatites which probably were partially recrys tallized during t h e emplacement of the svart hamaren charnockite batholith. geochronology previous works two distinctly different age provinces are separated by t h e j-p rz in western dronning maud land (fig. 1). to the west of the rift zone archean basement, 3,100-2,800 ma old (halpern 1970; elworthy 1982), covered by almost undeformed 1,850-760 ma old fluvial and volcanic sediments. to the east of the zone isotope data have been interpreted t o record a regional metamorphic phase of 1,00&1,200 m a (elworthy 1982), coeval with the bunger orogeny of east antarctica (angino & turner 1964; deutsch & webb 1964) and the nimrod orogeny of the trans antarctic mountains (grindley & mcdougall 1969). elworthy (1982) also inter preted a thermal event about s o ( h 0 0 m a old, comparable t o the ross orogeny (elliot 1975). because the two provinces show such a contrasting history, different degrees of deformation and metamorphic grade, the j-p rz is believed to be a deep crustal discontinuity with probably significant lateral displacement. t h e youngest igneous activity associated with the j-p r z is a 155-140ma old nepheline syenite in the northeastern part of h . u . sverdrupfjella. 170 ma old mesozoic dolerite lavas and dykes, similar to the ferrar dolerite of the trans antarctic mountains, are known from some places to the east of the zone. t h e radiometric ages obtained until 1989 in western dronning maud land are shown in fig. 1. both in kirwanveggen (wolmarans & kent 1982) and h . u . sverdrupfjella (grantham e t al. 1988) in the southwestern extension of the present area t h e older gneisses and migmatites have an age range from 1,186 to 8 6 1 m a (rb-sr, whole rock and u-pb zircon, elworthy 1982; moyes 1989). elworthy (1982) interpreted some of these ages as t h e record of the main metamorphism, and inferred that the rocks had a relatively short history prior t o the metamorphism, on the basis of low initial 87sr/86sr ratios. granitic, intermediate and mafic intrusions from the same area fall in an age range from 918 t o 519ma (moyes 1989). nearly all rb-sr mineral ages and k-ar mineral and whole rock ages from kirwanveggen in t h e west t o miihlig-hof 122 y . ohta, b . 0. tqrudbakken & k . shiraishi mannfjella in the east fall in a 55c-330ma age range (ravich & krylov 1964; krylov 1972; elworthy 1982; moyes 1989). location and description of the samples five types of rocks were sampled at three localities, x, y and z shown in figs. 2 and 6. each sample weighed 3-6 kg and explosives were used to obtain fresh rock samples. felsic gneiss of the jutulsessen metasupracrustals. ten samples of felsic gneiss were collected from the middle succession of the jutulsessen metasupracrustals. the bulk composition of the rock is granodioritic and the main minerals are oligoclase, microline, quartz and some biotite. the samples have only very weak gneissic fabric. metagabbro. nine samples of metagabbro were collected northwest of stabben in the northeastern part of jutulsessen. the metagabbro has a sharp intrusive contact to the jutulsessen metasupracrustals. the samples were chosen to cover as many lithological varieties of the gabbro as possible. the mineral assemblage is plagioclase (andesine-oligoclase), pale green clinopyroxene, brown biotite, green hornblende and olivine in some samples. the modal composition varies considerably between the samples. opaque minerals, sphene and apatite are the accessories. clinopyroxene is partly converted into green hornblende. the lithological variation is believed to be caused by magmatic differentiation and successive hydrothermal processes, and original igneous textures are well preserved. charnockite. -this rock was sampled in southern svarthamaren and care was taken to avoid the light coloured parts which may be contaminated facies with assimilated foreign materials. the nine samples collected are medium-grained, dark yellow-brown charnockite without preferred mineral orientation. these rocks have tabular potash-feldspar often with very small opaque inclusions, quartz, oligoclase, dark brown biotite, brown clinopyroxene and occasional orthopyroxene grains as the main constituents. the bulk composition is granitic to granodioritic. grey aplitic and dark basic dykes, cutting the medium-grained charnockite. -two types of dyke cutting the charnockite in svarthamaren were chosen for the isotope study. the gray aplitic dyke is the youngest dyke, and consists of oligoclase, microcline, brown-green biotite, green hornblende, quartz and opaque grains. the samples are uniform and have granodioritic bulk composition. the dark dyke (metabasite) has a basic bulk composition, and consists of oligoclase, dark brown biotite, clinopyroxene and accessory amounts of opaque grains and apatite. this rock is cut by the grey aplitic dyke and locally they form composite dykes. analytical techniques rb-sr ratios were determinzd by x-ray fluor escence spectrometry. measurements of unspiked 87sr/86sr were made on a vg micromass 30 at mineralogisk-geologisk museum, oslo, using procedures similar to those described by pankhurst & o'nions (1973). variable mass discrimination in 87sr/86sr was corrected by normalizing 88sr/ 86sr to 8.3754. the 87rb decay constant used is 1.42 x 10-"y-' and the regression technique was that of york (1969). age and intercept errors are quoted at the 2 sigma level. results and discussion felsic gneiss, middle jutulsessen. high sr and relatively low rb contents did not give a spread in the rb/sr ratios sufficient enough to allow an age calculation (table 8). therefore, only two samples were analysed for sr isotope composition. the obtained 87sr ratios, 0.70576 t 0.00016 and 0.70482 ? 0.00018, may be regarded as maximum numbers of the initial 87sr/86sr ratio. assuming an age of 1,100 ma, referring to the results from h.u. sverdrupfjella and kirwanveggen, the calculated initial 87sr/86sr ratios for the two samples are 0.7029 and 0.7014 (fig. 10). these are close to the lowest values which are geologically reasonable. although no definite conclusion is possible, the calculation suggests that the felsic gneiss could fall into the same groupasthegneissesdatedin h.u. sverdrupfjella, or be younger. metagabbro, northeastern jutulsessen. very similar rb/sr ratios made age determination impossible for this rock (table 8). the sr isotopes were analysed in four samples and they show some scatter on the isotope diagram (fig. 10). this scatter may be due to a slight disturbance geology of gjelsuikfjella and western miihlig-hofmannfjella 123 jjtulsessen i %r/%r 710 + + + met a g a b b r o + i / 4 ' 'felsic gneiss i i 705, + 87 r b/%r . 2 ./l .6 .a fig. 10. isotope diagram for the felsic gneiss of the jutulscsscn mctasupracrustals and mctagabbro (rcf. table 8). of the isotope system. however, all samples show relatively high 87sr/86sr ratios from 0.70785 to 0.70874. this may indicate that a relatively high initial ratio can be inferred for the metagabbro. such high initial ratios have commonly been obtained from the mafic rocks to the west of the j-p r z , and have been interpreted by elworthy (1982) and barton & copperthwaite (1983) to be due to an undepleted mantle source or crustal contamination. charnockite, suarthamaren, miihlig-hofmann fjella. acceptable spread in the rb/sr ratios enabled whole rock age determination of the medium-grained charnockite (table 9). the regression calculation gave an isochron age of 500 f 24ma with m.s.w.d. = 1.64 (fig. 11). this age is interpreted as the age of crystallization, and is regarded as the most reliable age for the emplacement of the large charnockite massif in muhlig-hofmannfjella (e.g. ravich & krylov 1964; krylov 1972). this intrusion event is coeval to the ross orogeny of the trans antarctic tuhle 8. r b and sr analyscs of the fclsic gnciss and metagabbro from jutulscsscn f c l ~ gneiss sample n o rh' sr* x7rb/x6sr 87sr/86sr s e ' * es e6a e l e2 eb e4 ehb e6c e7 exa e8b e8c ey el08 elob 83 y5 83 70 82 95 93 85 95 98 111 63 88 91 86 1322 1264 1294 12x1 i278 l2by 130y 1294 i170 i253 1290 1297 1596 1132 1170 metagabbro sample no. rb* sr* 87rb/86sr 87sr/86sr se** a 46 790 171 70874 00012 di 114 2y01 1 i 3 70785 000 14 d2 116 2697 124 70868 00012 ti 71 381h 052 70804 00010 b 120 3208 c1 20 1408 c 2 23 1308 f1 75 3464 f7. 71 3846 *ppm **2 sigma 124 y . ohta, b. 0. tprudbakken & k . shiraishi table 9. rh and sr analyses of the charnockite and associated dyke rocks from svarthaniaten charnockite sample n o . rh* sr* 87rhl86sr 87sr186sr se*' h1 h2 h4 h5a h5b h 6 h 7 h8 h9 26 1 264 27 1 385 290 226 211 205 211 greyaplitic dyke sample no. rb' 1 50 156 153 192 159 159 i76 158 184 sr* 5.06 4.92 5.15 5.83 5.30 4.13 3.58 3.17 3.33 .74685 .74580 .74753 ,75123 ,74834 .74004 ,73593 ,13796 ,73401 87rb186sr .00018 ,0001 4 .000 12 ,00014 .00012 .o(jo02 .00002 .00002 .00002 se*' ~~ ji 152 454 ,970 ,71527 .00002 j4 234 192 3.54 .73635 .moo2 j7 15 1 456 ,961 ,71520 .00002 jy 153 448 ,987 ,71538 ,00003 53 149 464 j5 150 464 56 151 452 j x 152 451 dark dyke, svarthamaren sample no. rb* sr* 87rb186sr 87sr/86sr se** k i 88 1694 ,150 ,70996 .00002 *ppm '*2 sigma mountains. evidence of deformation related to this orogeny in western dronning maud land is so far restricted t o the folding of the lower paleozoic sediments (the urfjell group), out cropping in southern kirwanveggen (aucamp et al. 1972). a relatively high initial 87sr/86sr ratio of 0.71057 * 0.00071 for the charnockite is probably related to crustal contamination, since many partly assimilated xenoliths of gneiss and migmatite have been observed along the marginal areas of the charnockite body. grey aplitic and dark basic dykes, suarthamaren, miihlig-hofmannfjella. no significant spread in rb/sr ratio, except for one sample, was obtained for the grey aplitic dyke and accordingly, only four samples were analysed for sr isotope composition (table 9). the results, together with the analysis of the dark basic dyke and a reference line corresponding to the charnockite isochron, are plotted in fig. 12. from their crosscutting occurrence both types of dykes are younger than the medium-grained charnockite. i n addition, the two kinds of dykes sometimes occur as composite dykes, suggesting their comagmatic derivation. no meaningful age, therefore, can be obtained for the grey aplitic dyke, or for any combination of this rock with the dark basic dyke. the scatter in the isotope diagram possibly reflects originally different initial rb/sr ratios, due to magmatic differentiation processes. conclusions 1. the bedrock of gjelsvikfjella and western muhlig-hofmannfjella is essentially composed of two metamorphic-igneous rock units: firstly the jutulsessen metasupracrustals and snotoa metamorphic complex and secondly the svart hamaren charnockite batholith. 2 . the age of the regional metamorphism could not be determined in the present study. however, it can be assumed to be about 1,100 ma old from the structural and lithological continuities with the geology of gjelsuikfjellu and western miihlig-hofmannfjellu 125 87s r-186~ r -15 svarthamaren i charnockite / age: 5 0 0 2 2 4 ma i r:0.7 1037 20.00071 ms w d: 1.64 fig. 11. isotope diagram for thc 87r bib6si 2 3 4 5 6 charnockite from southern svarthamaren (ref. table 9). rocks of h.u. sverdrupfjella and kirwanveggen. around 1,100 m a is a possible age for the felsic gneiss of the jutulsessen metasupracrustals. 3. the sngitoa metamorphic complex consists of granulite facies banded gneisses and migmatites intruded by medium-grained charnockite. t h e medium-grained charnockite includes a large proportion of gneiss and migmatite xenoliths and intruded into the s n ~ t o a metamorphic complex about 500 m a ago. coarse-grained charnockite ' 7 ~ r ~ 8 6 ~ r ' / p' svarthamaren ,// / / 73 / / / / / / , / / 0 o grey felsic dyke 0 dark basic dyke 1 2 3 87rw86s~ fig. 12. isotope diagram for the dykes from southern svarthamaren (ref. tahlc 9). makes u p the major part of the svarthamaren charnockite batholith, which is extending far to the east of the mapped area. t h e cooling process after this thermal event is probably recorded in the mineral ages u p to about 400 ma. 4. t h e regional metamorphism was originally an intermediate pressure type, upper amphibolite facies t o granulite facies. this was probably modified into a high temperature type facies by later thermal influence during the emplacement of the svarthamaren charnockite batholith. 5 . a similar two-stage igneous-metamorphic history is also known from eastern dronning maud land from sgir rondane to prins olav coast by t h e studies of japanese expeditions (e.g. shiraishi e t al. 1987). although the area in middle dronning maud land from 6"e t o 20"e has not been mapped in detail, this two-stage tectonic history seems t o be common in dronning maud land east of t h e j-p rz. acknowledgements. thc authors would like to thank two anonymous reviewers and alastair allen for helpful suggcstions and commcnts on the manuscript. kurt buchcr-nurmincn and hbkon austrheim rcad and commented on an early draft of the manuscript. we would also like to thank anne lund for her exccllcnt handling of thc word processor. references allen, a . r. 1990: thc tcctonic and metamorphic evolution of h.u. sverdrupfjella, wcstcrn dronning maud land, antarctica. in thomson ct al. (cds.): geological evolution of anfurcticu. cambridge university press (in press). angino, e. e. & turner, m. d. 1964: antarctic orogenic belts as delineated by absolute age dates. pp. 552-556 in adie, r. j. (ed.): anrurcric geology. north holland puhl. c o . , amsterdam. 126 y . ohta, b . 0. torudbakken & k . shiraishi aucamp, a . p. h . , wolmarans, l. g . & neethling, d. c. 1972: the urfjell group, a deformed (?) early palaeozoic sedimentary sequencc, kirwanveggen, western dronning maud land. pp. 557-562 in adie, r . j. (ed.): antarctic geology and geophysics. universitetsforlaget, oslo. barton, j . m., jr. & copperthwaite, y . e. 1983: sr-isotope studies of some intrusive rocks in the ahlmann ridge and annandagstoppane, western queen maud land, antarctica. pp. 59-62 in oliver, r . l . , james, p. r . & jago, j . b. (eds.): antarctic earth sciences. australian academy of science, canberra, and cambridge university press. bohlcn, s . r., wall, v. j . & boettchcr, a . l. 1983: gcobaromctry in granulites. pp. 141-171 in saxcna, s . k. (ed.): kinetics and equilibrium in mineral reactions. springcr, new york. dcutsch, s. & webb, p. n. 1964: sr/rh dating on basement rocks from victoria land. pp. 557-562 in adie, r. j . (ed.): antarctic geology. north holland publ. co., amsterdam. elliot, d. e. 1975: tectonics of antarctica, a rcview. a m . jour sci. 275, 45-106. elworthy, t . p. 1982: gcochronology. pp. 73-86 in wolmarans, l. g. & kent. l. e. (eds.): geological inoestigations in wrstern dronning maud land, antarctica a synthesis. s . afr. j. antarct. res. suppl. 2 . grindley, g . m . & mcdougall, 1. 1969: age and correlation of the nimrod group and other precambrian rock units in thc central trans-antarctic mountains, antarctica. new zealund jour. geol. geophys. 12, 391-411. grantham, g . h . , groenewald, p. b . & hunter, d. r . 1988: gcology of thc northern 1i.u. sverdrupfjclla, western dronning maud land, and implications for gondowana rcconstructions. s. a f r . 7: nau. antarct. i x ( i ) , 2-10. halpcrn, m. 1970: rubidium-strontium datc of possibly three billion years for granitc rocks from antarctica. science 169, 977-978 hjelle, a. 1972: some observations on the geology of h.u. svcrdrupfjella, dronning maud land. norsk polarinst. .4 .&k 1972, 7-22. holdaway. m . j. 1971: stability of andalusite and the aluminium silicatc diagram. a m . jour. sci. 271, 97-131. holdaway, m. j . & lee, s . m. 1977: fe-mg cordierite stability in high grade pelitic rocks based on experimental, theoretical and natural observations. contr. miner. petrol. 63, 175 198. krylov, a . ya. 1972: antarctic geochronology. pp. 491-494 in adic, r . j . (ed.): antarctic geology and geophysics. universitetsforlaget, oslo. moyes, a . b . 1989: a compilation of radiogenic isotope data f r o m western dronning maad land, antarctica. preprint distributed at international workshop on antarctic geo chronology, miinchen, 1989. 9 pp. neethling, d. c. 1972: age and corrclation of the ritscher supergroup and other precambrian rock units, dronning maud land. pp. 547-556 in adie, r . j . (cd.): antarctic geology and geophysics. universitetsforlaget, oslo. newton, r . c. & haselton, h. t . , jr. 1981: thermodynamics of the garnet-plagioclase-ai,sio,-quartz geobarometer. pp. 131-147 in newton, r . c., navarotsky, a. & wood, b. j . (eds.): thermodynamics of minerals and melts. springer, new york. pankhurst, r . j . & o'nions, r. k . 1973: dctcrmination of rh/sr and 87sr/86srs ratio of some standard rocks and evaluation of x-ray fluorescence spectrometry in rh-sr gcochemistry. chemical geol. 12, 127-136. percival, j. a . 1983: high grade metamorphismin the chaplcau folyet area, ontario. a m . miner. 68, 667-686. ravich, m. g. & solovicv, d. s. 1966: geology and petrology of the mountains of central queen maud land (eastern antarctica). trans. sci. rcs. institute of arctic geol., ministry of geology, ussr. 141 pp. (translated in jerusalem. 1969). ravich, m. g. & krylov, a . ya. 1964: absolute ages of rocks from east antarctica. pp. 590-596 in adie, r . j . (cd.): antarctic geology. north holland publ. co.. amsterdam. richardson, s . w. 1968: staurolite stability in a part of thc system fe-ai-si-0-11. jour. petrol. 9 , 467-488. ringwood, a. e. & green, d. h . iy66: an experimental investigation of the gabbro-cclogite transformation and somc geophysical implications. tectonophys. 3 . 38?-427. roots, e. f. 1953: preliminary note on the geology of western dronning maud land. norsk geol. tid.s.\kr. 3 2 , 17-33. roots, e . f. 1969: geology of western queen maud land. antarctic map folio series, foho 12, plule 6. am. geogr. soc. shiraishi, k., hiroi, y . , motoyoshi, y. & yanai, k. in press: plate tcctonic development of late proterozoic paired metamorphic complex in eastern queen maud land, east antarctica, proceedings of 6th gondowana symposium, american geophysical union. thompson, j . b . 1976: mineral reactions in pelitic rocks. 11. calculation of some p-t-x (fe-mg) phase relations. american jour. sci. 276, 425-454. wolmaranb, l. g . &kent, l. e. 1982: geologicalinoestigations in western dronning maud land, antarctica a synthesis. s. a f r . j. antarct. res., suppl. 2 . 93 pp. wones, d. r. & gilbert, m. c . 1969: thc fayalitc-magnetite quartz assemblage between 600" and 800°c. american jour. sci. 267-a, 480. wood, b. j. & banno, s. 1973: garnet-orthopyroxcnc and orthopyroxene-clinopyroxene relationships in simple and complex systems. contr. mineral. petrol. 42, 109-124. yiirk, d. 1969: least squares fitting of a straight line with correlated errors. earth and planetary sci. letterv 5 , 32& 324. bookreviews03.indd 210 book reviews in using phoca hispida rather than pusa hispida for the ringed seal and phoca groenlandica rather than pagophilus groenlandicus for the harp seal, but this can be a matter of personal preference; there is in fact no “offi cial” world list of scientific names. there is very little to criticize and much to laud in the production and editing of the book. i could fi nd only one typographical error (ridgway’s name is spelled wrong in the list of recommended readings). the binding is fi ne, and the photographic illustrations and other graphics are superb. a quick-identifi cation sheet and forms for reporting sightings are provided in a pocket at the back. this guide should provide good and long service in the fi eld and may result in collection and collation of sightings potentially useful to the scientifi c understanding of these fascinating animals. it is highly recommended for accurate information on the marine mammals one is likely to encounter in and around the far-northern arctic territories of norway. review of marine mammals of svalbard, by k. m. kovacs, i. gjertz & c. lydersen olle melander the swedish tourist authority, box 860, se–101 37 stockholm, sweden. every year, tourists converge on svalbard hoping to catch sight of the big marine mammals. but most tourists are not zoologists. for a temporary visitor, it is no easy task to recognize marine mammals. of course polar bears and walruses are easy to distinguish—and they also top the visitor’s wish list—but tourists also want to see seals and especially whales. these animals seldom “pose” the way polar bears and walruses sometimes do. they may give you no more than a brief glimpse and then leave you wondering: what was that? how big is a seal? what does it eat? as of last summer, tourists and tour guides have a new way of fi nding answers to their questions about svalbard’s fauna: kovacs et al. marine mammals of svalbard. but there are already several fi eld guides and a substantial body of scientifi c literature. does this book add anything new? this is an appealing book in terms of design, size, text and content. it is just the right size to take along with you, and just the right thickness to invite reading. the book itself is too big to shove into your pocket, but just inside the back cover you will fi nd an identifi cation sheet with drawings of the animals. at least you can always carry the id sheet with you. passengers on cruise ships will not fi nd the book’s size any problem. it can be kept close at hand in case you want to read up on animals that have been observed. the authors are knowledgeable. the descriptions of the animals are clear and comprehensible. the language is precise and formulated with scientifi c caution. known facts are described with care; if uncertainties remain, this is stated. the book is clearly organized and its structure easy to grasp. information is presented consistently under the same headings for each individual species. this makes it easy to fi nd one’s way around in the book. it contains more photographs and drawings than other, similar books. the photographs are not all of top quality, but here perhaps the publisher is more to blame than the authors. even though the book is entitled marine mammals of svalbard, it contains general information and glimpses of other parts of these animals’ ranges. thus it can be of use even to people who are not visiting svalbard specifi cally. as the book states in several places, information concerning the range, population, etc. of the marine mammals is uncertain. the authors, whose research fi eld is the mammals of svalbard, give modest population estimates. is this an expression of scientifi c conservatism? how uncertain are the estimates? more knowledge is needed, and in the preface, the authors hope readers visiting svalbard will be inspired to report the animals they see by sending in the sighting sheet tucked into a sleeve at the end of the book. though the aim is admirable, the authors bungle the job a bit by not giving clear reasons for the data collection. in addition, the sighting sheet is enormous, providing over 50 lines on which to report observations. what tourist has the stamina —or the luck—to make that many observations? one is reluctant to report a few scattered observations, which is all one usually gets on a short tourist outing. a postcard-sized reporting sheet, with the address pre-printed, and with a brief explanation of what the data will be used for, would inspire much more participation. in addition, many tourists visit svalbard more than once, though a few years may pass between visits. for them, it would be good if more than 211book reviews 2004: polar research 23(2), 209–213 one sighting card were provided. voluntary census takers also want to know where the data they have collected end up. a free-text search for “marine mammals” or “svalbard” on the norwegian polar institute website gives no hits. this doesn’t detract from the book in any way, but people would be more eager to send in observations if they could trace their contributions in the ongoing data compilation. the book is good and makes you hungry for more. it is also refreshing that the book keeps to the point, but what is the purpose of the map on page 1? why not a map showing the ranges of the animals the book is about? moreover, hunting of marine mammals has dominated svalbard’s history from the early whaling days to the polar bear hunting of modern times. hunting in svalbard and its devastating effect on these mammals would have been a more interesting topic than general comments about bowhead whales, steller’s sea cow and sea otters. the sections on seals and whales should both begin with a few general words concerning the relationships between the species and their evolution. the text is packed with interesting information, but a discussion of the future is called for: not just the future of the whales but of all svalbard’s marine mammals. if the ice at the north pole melts away, will there still be polar bears in svalbard? how many polar bears have been killed since they became protected? tourists ask a lot of questions; the authors would surely be able to provide answers. hopefully the next edition can provide indications of size for the whales on the identifi cation sheet. are they all rendered at the same scale? greater consistency in presenting the whales’ weight and size in text would make reading easier. for instance, it would be interesting to know where the fi gure 200 tonnes for the blue whale comes from, and what the average weight is. could the authors provide a few more references? as the number of tourists grows, it would be worthwhile listing the names of the whales in even more languages. the book is so good no nature-loving tourist going to svalbard should be without it. for people like myself, who guide tourists in experiencing svalbard’s fauna, the book is a gold mine, with its logical structure and clear text. it is affordable, easy to take along, and answers the questions. and when the sighting reports start coming in, it will hopefully lead to better knowledge about the marine mammals of svalbard. review of negotiating the arctic: the construction of an international region, by e. c. h. keskitalo (2004). new york and london: routledge. 282 pp. isbn 0-415-94712-x. oran r. young bren school of environmental science and management. university of california (santa barbara), 4518 bren hall, ucsb, santa barbara, ca 93106-5131, usa. since the waning of the cold war during the late 1980s, the arctic has emerged as a lively arena for initiatives designed to promote international cooperation. these initiatives take a variety of forms. some, like the arctic environmental protection strategy (aeps) and its successor the arctic council (ac), involve intergovernmental agreements. others, such as the northern forum (nf), are collaborative efforts on the part of subnational units of government (e.g. counties, provinces, states). still others, like the international arctic science committee (iasc), the university of the arctic (uarctic), and the inuit circumpolar conference (icc), feature efforts on the part of nongovernmental bodies to infl uence the course of transnational relations. how can we explain this development? and what are the prospects for a broadening and deepening of arctic cooperation during the foreseeable future? this intriguing, albeit sometimes diffi cult and frustrating, book seeks to answer these questions by focusing on the idea of region-building, deploying the methods of social constructivism, and making liberal use of discourse analysis. the result is an analysis that has the salutary effect of making us stop to think about the underpinnings of cooperation in the arctic, even though it may have little impact on the actual course of events in this dynamic region. is there an arctic discourse? what methods are appropriate for answering this question? keskitalo’s central argument is that such a discourse has emerged during the last 20-30 years and that it refl ects in large measure the views and perspectives of canada and, to a lesser degree, those of the icc (treated as a partner of canada with regard to circumpolar issues). the evidence underlying this << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <feff004200720075006700200064006900730073006500200069006e0064007300740069006c006c0069006e006700650072002000740069006c0020006100740020006f0070007200650074007400650020005000440046002d0064006f006b0075006d0065006e0074006500720020006d006500640020006800f8006a006500720065002000620069006c006c00650064006f0070006c00f80073006e0069006e0067002000740069006c0020007000720065002d00700072006500730073002d007500640073006b007200690076006e0069006e0067002000690020006800f8006a0020006b00760061006c0069007400650074002e0020005000440046002d0064006f006b0075006d0065006e007400650072006e00650020006b0061006e002000e50062006e006500730020006d006500640020004100630072006f0062006100740020006f0067002000520065006100640065007200200035002e00300020006f00670020006e0079006500720065002e00200044006900730073006500200069006e0064007300740069006c006c0069006e0067006500720020006b007200e600760065007200200069006e0074006500670072006500720069006e006700200061006600200073006b007200690066007400740079007000650072002e> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice no job name is climate change causing the increasing narwhal (monodon monoceros) catches in smith sound, greenland?por_106 238..245 martin reinhardt nielsen faculty of life sciences, university of copenhagen, bülowsvej 17, dk-1870 frederiksberg c, denmark abstract this paper evaluates recent changes in narwhal (monodon monoceros) catches in siorapaluk, the northernmost community in greenland, in consideration of the effects of changing climate and uncertainty of stock delineation. the catch statistics show a significant increase in narwhal catches by hunters in siorapaluk after 2002, which does not appear to be a result of increased effort. hunters attribute the increase to changed sea-ice conditions providing access by boat to smith sound as early as june and july. this indicates that climate change is likely to have a considerable impact on narwhal hunting in northern greenland. traditional ecological knowledge and scientific surveys suggest that narwhal in smith sound constitute an independent stock. the absence of scientific recommendations for this stock has been seen as an opportunity to increase quotas in west greenland. scientific management recommendations are urgently needed to allow the authorities to assign sustainable quotas for this stock. the development of collaborative management agreements and locally based monitoring are recommended to ensure local acceptance of regulations, and to allow rapid responses to climate change. keywords climate change; greenland; monodon monoceros; narwhal; whale management; whaling. correspondence martin reinhardt nielsen, faculty of life sciences, university of copenhagen, bülowsvej 17, dk-1870 frederiksberg c, denmark. e-mail: nielsenmr@gmail.com doi:10.1111/j.1751-8369.2009.00106.x three independent stocks of narwhal (monodon monoceros) are currently recognized in greenland waters (heidejørgensen & laidre 2006). the summer stock at inglefield bredning, in qaanaaq municipality, is considered to be the same stock that is caught in autumn and winter in uummannaq municipality and the disko bay area (heidejørgensen et al. 2005), with individuals straying only rarely as far south as maniitsoq. this stock is referred to as the west greenland stock. the summer stock in melville bay is caught by hunters from upernavik municipality and from savisivik in qaanaaq municipality. this stock spends the winter in the central part of baffin bay (dietz & heide-jørgensen 1995). narwhal in east greenland are genetically distinct from stocks in west greenland (palsbøll et al. 1997), and are considered to comprise one stock, largely because of a lack of information (nielsen, unpubl. ms.). surveys reveal that the narwhal summer stock in inglefield bredning halved over the course of 20 years (heide-jørgensen et al. 2002). the west greenland winter population has also been reduced, and the latest population assessment predicts local extinction of this stock in less than 30 years if current harvest levels continue (jcnb/ nammco 2004). no reliable population estimates are available for the melville bay stock. quotas were introduced by the greenland home rule government through an executive order on protection and hunting of beluga and narwhal in 2004. management advice is provided by the canada–greenland joint commission on conservation and management of narwhal and beluga (jcnb). the jcnb receives scientific recommendations on harvest sustainability by a joint working group (jwg) comprising the jcnb scientific working group and a working group from the scientific committee of the north atlantic marine mammal commission (nammco). the jwg recommends a maximum catch of 135 narwhal from the west greenland stock (witting 2005). however, uncertainty surrounds the stock delineation of narwhal populations in baffin bay and the northern strait between greenland and canada, the so-called smith sound, which in the winter constitutes part of the north water polynya (heide-jørgensen et al. 2005). unclear stock delineation and the lack of reliable population estimates prevent the assignment of population-specific quotas to the relevant greenlandic municipalities, where isolated communities depend on narwhals as a source of nourishment and income (stevenson et al. 1997; freeman et al. 1998). the urgency to solve this problem increases as the greenland polar research 28 2009 238–245 © 2009 the author238 mailto:nielsenmr@gmail.com home rule government repeatedly exceeds quota allocations proposed by its department of fisheries, hunting and agriculture (dffl). it is important to ensure that information on sustainable harvest levels is available for all stocks, so that the lack of information cannot be used as an argument for increasing quotas that would otherwise have been gradually reduced in accordance with scientific advice. the potential effects of climate change on narwhal populations also remain uncertain. generally, declining arctic sea-ice trends are expected as a result of climate change (symon et al. 2005; solomon et al. 2007). remotely sensed sea-ice concentrations in the period 1979–2001, however, indicate a decreasing fraction of open water and increasing interannual variability in narwhal wintering grounds in central baffin bay (laidre & heide-jørgensen 2005). these wintering grounds are critically important for narwhal energy intake and overall fitness, suggesting that recent changes entail an increased risk of ice entrapment and vulnerability (laidre & heidejørgensen 2005). this result extends to jones sound in the north water polynya for the month of march (heide-jørgensen & laidre 2004). however, as sea-ice concentrations are primarily driven by wind and current patterns as well as by temperature (heide-jørgensen et al. 2007), trends may vary according to local conditions, and may result in less sea ice locally. the potential effects of reduced sea-ice cover on marine mammal stocks include nutritional stress resulting from the redistribution of prey, changes in survivorship or fecundity, and altered migration routes or timing caused by changing ice patterns (simmonds & isaac 2007). the effects on higher tropic levels are, however, particularly difficult to investigate, because they involve relationships that may be nontrivial, non-linear and affected by time lags (lusseau et al. 2004; leaper et al. 2006). furthermore, few studies have considered the impact of changing hunter behaviour as a result of climate change (but see stirling & parkinson 2006). the aim of this paper is therefore to evaluate the recent changes in narwhal catches in siorapaluk, in consideration of the effects of changing climate as well as the uncertainty of stock delineation. study area siorapaluk (77°47′n, 70°43′e) is the northernmost community in greenland and the one nearest to smith sound (fig. 1). the community has a church, school, a general store and electricity, but no running water. there are approximately 60 inhabitants, of which 16 held an occupational hunter’s license and seven held a part-time hunter’s license in 2004. almost all households depend on hunting and fishing for subsistence and income. halibut, seal, narwhal, walrus, polar bear, reindeer, muskoxen and various birds are caught. sealskin and halibut are produced for the national market, but only in small quantities on account of limited local freezer capacity, and because the products have to be transported to qaanaaq to be sold. particularly valuable catches such as narwhal, which may bring in the equivalent of approximately 5800 usd for an adult (nygård & topp-jørgensen 2007), are also occasionally transported for marketing in qaanaaq. however, often narwhal is not traded because it is considered to be of high cultural value, and important for the upkeep of social relationships through traditional sharing practices (sejersen 2001). hunting and fishing is carried out exclusively using dog sledges on the sea ice and from small dinghies. in accordance with qaanaaq municipality by-laws, narwhal are hunted with handheld harpoons with attached floats, and from kayaks, which are transported to the hunting area by dinghies: sometimes dinghies are dragged over long stretches of sea ice. the actual kill is undertaken with a rifle once the narwhal has been secured with several floats. methods siorapaluk was selected as the focal research community as it had been identified as a location of a considerable increase in narwhal catches. the evaluation is based on quantitative and qualitative inquiry, including catch statistics, information on the number of hunters and focus group discussions. the siorapaluk catch statistics were extracted from the national catch database, piniarneq, for the period 1993–2004. all hunters record catches per month, and report their annual catch to the dffl, which maintains the database. reported catches were verified during meetings or subsequently by telephone. prior to 2004, narwhal hunting was permitted for both occupational and part-time hunters. information on the number of active hunters in the period 1993–2004 was extracted from the national hunting license register. sufficiently detailed and reliable data are not available for siorapaluk prior to the establishment of piniarneq (see heidejørgensen 1994). statistical tests were conducted with sas software. correlations were tested with the pearson product-moment correlation coefficient. significant differences in the means were tested with the mann– whitney u-test. semi-structured focus group discussions (bryman 2004; lloyd-evans 2006) on narwhal hunting, hunting methods and the impacts of climate change were conducted in greenlandic, with the aid of a local interpreter, with 12 members from the local hunting organization, knapk, and four members of the village board, on 30 november and 1 december 2006, respectively. all is climate change increasing narwhal catches?m.r. nielsen polar research 28 2009 238–245 © 2009 the author 239 hunters in the community were invited for the discussion, and as more than half of the hunters and the village board participated in the discussion the results are considered to be representative for these groups. a meeting was also conducted with four members of the board of knapk in qaanaaq on 3 december 2006. this approach was selected so that information could be collected from the primary stakeholders, including individual hunters, local hunting organizations and local authorities. semistructured focus group discussions were selected instead fig. 1 map of (a) greenland, with insets (b) and (c) of the study area. is climate change increasing narwhal catches? m.r. nielsen polar research 28 2009 238–245 © 2009 the author240 of more open-ended or structured methods, to ensure the collection of the required information while retaining a measure of flexibility (bryman 2004; lloyd-evans 2006). the key points raised were reviewed with the local interpreter immediately after the focus group discussions, and after the completion of the fieldwork a summary report was forwarded to the local knapk and the village board for verification and validation, and to allow for the consideration and inclusion of further comments. the consensus results of the discussions are reported unless otherwise stated. names of participants and respondents have been kept confidential to protect their privacy. results the results (fig. 2) illustrate a significant increase in narwhal catches by hunters in siorapaluk after 1998, compared with previous data (u6.6 = 0; p < 0.05). no significant correlation was found between the size of the catch and the total number of hunters (r12 = 0.42, p > 0.05), or the number of occupational hunters (r12 = 0.49, p > 0.05), suggesting that the increased catch is not a result of increased effort, assuming that hunting technology and the narwhal distribution have remained relatively stable throughout the period. these assumptions may not be valid, and will be considered in the discussion. hunters in siorapaluk attribute the increased catch to the changing sea-ice conditions in smith sound. previously, narwhal populations in smith sound were only accessible by dog sledge on the sea ice, and, according to the hunters, no one travelled there to hunt narwhal. one hunter from siorapaluk recalled traveling to smith sound by dog sledge in may 1976 on a polar bear hunt, and seeing large pods of narwhal. according to the hunters, the formation of the ice is occurring later, the ice is thinner, it breaks up earlier, and, since 1998, smith sound can therefore be accessed by boat as early as june or july. this is supported by a substantial change in the distribution of the catch, with the bulk of the catch caught in june and july after 1998 (fig. 3). a more detailed look at the catch statistics, breaking it down into three periods, indicates a close connection between the catch and the number of hunters in the period 1993–98 (see fig. 2), although no significant correlation was found (r6 = 0.48, p > 0.05). the increasing number of hunters from 1999 to 2001 may explain the increasing catch in this period. however, from 2002 the number of hunters has remained stable, whereas the catch has almost tripled. this suggests that that effect of changing ice conditions on narwhal hunting, as emphasized by the hunters, cannot be disentangled from the effects of increased effort, until 2002. from july 2004 quotas were introduced on narwhal hunting in west greenland. unfortunately, remotely sensed sea-ice data are not readily available at sufficient spatial and temporal resolution for smith sound to enable correlation tests with the catch from 1993 to 2004 (laidre, pers. comm.). similarly, the air-temperature records available from qaannaq and the carey islands are of dubious utility in this context, because of the distance from smith sound, and because local sea-ice concentrations are determined by wind and current patterns, as well as by temperature (heide-jørgensen et al. 2007). assessing the correlations reported here with measures of climate change is thus beyond the scope of this study. documentation of similar changes in sea-ice cover is, however, abundant from other locations in the arctic, and will be considered in the discussion. hunters in siorapaluk consider the narwhal in smith sound to be a separate population that either migrates between canada (ellesmere island and humbolt brink) and greenland, or remains in smith sound all year round. according to local knowledge, the winter population is very variable. narwhal hunting in smith sound is primarily carried out by hunters from siorapaluk, but hunters from qaanaaq and perhaps moriusaq are 0 10 20 30 40 50 60 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 catch hunters fig. 2 narwhal catch by hunters from siorapaluk and total number of hunters in the period 1993–2004. 0 10 20 30 40 50 60 70 ja nu ar y fe br ua ry m ar ch ap ril m ay ju ne ju ly au gu st se pt em be r o ct ob er n ov em be r d ec em be r 1993-1998 1999-2004 fig. 3 percentage of accumulated narwhal catches by hunters in siorapaluk per month, before and after 1998. is climate change increasing narwhal catches?m.r. nielsen polar research 28 2009 238–245 © 2009 the author 241 increasingly targeting this area as well. this means that the increase in the catch in smith sound may be higher than fig. 2 indicates. according to the knapk in qaanaaq, approximately three boats from qaanaaq hunt narwhal in smith sound, and annually return with between one and three narwhal each. it was also rumoured that unlicensed hunting is on the increase. the window of opportunity is, however, decreasing: according to the hunters, the break-up of the ice occurs earlier and earlier, causing the narwhal to disperse and head to the fjords. discussion and recommendations the hunters’ observations of changes in sea ice correspond to scientifically documented changes in sea-ice cover, ice thickness, and dates of freeze and break-up in the arctic (johannessen et al. 1999; maslanik et al. 1999; parkinson et al. 1999; rothrock et al. 1999; copley 2000; rigor et al. 2002; rothrock et al. 2003; serreze et al. 2003; comiso & parkinson 2004; fowler et al. 2004; gough, cornwell et al. 2004, gough, gagon et al. 2004; gagon & gough 2005; lindsay & zhang 2005; rothrock & zhang 2005; stroeve et al. 2005; stirling & parkinson 2006). they also correspond to changes observed by inuit in other parts of the arctic (see review in laidler 2006). these changes are considered to be the result of anthropogenic climate change (solomon et al. 2007). the results indicate that climate change is likely to have been making a considerable impact on narwhal hunting in smith sound since 2002, and potentially since 1999. this conclusion is based on the assumption that hunting technology and narwhal distribution and stock size have remained stable. all vessels used by occupational hunters must be registered in the greenland vessel register managed by the greenland fisheries license office (gflk). gflk has, however, only received three reports from qaanaaq municipality. the reports mention one vessel in 1992, two more in 1993 and another two in 1999, bringing the total to five dinghies in siorapaluk, all below 4 gross metric tonnes. the danish maritime authority registered one vessel in siorapaluk in a survey in 2000, and none in 2007. however, in the period 2000–02, about 13 600 usd was allotted to support the purchase of three 19-foot/115-horsepower dinghies by occupational hunters in siorapaluk, from the home rule government’s fund for development of the hunting sector. no information is available on vessels owned by part-time hunters. because of the incomplete information about vessels in use, it cannot be ruled out that improvement in technology has had an effect on narwhal hunting by hunters from siorapaluk. based on the available information and observations of vessels, and the lack of snowmobiles in siorapaluk, it is, however, considered unlikely that improved technology is the main reason for the increase in catch from an average of two whales per year from 1993 to 1998 (95%; ci [confidence interval] � 0.05), to 30 whales per year from 1999 to 2004 (95%; ci � 0.37). aerial surveys conducted in june recorded narwhals in smith sound at the same time as pods were observed at inglefield bredning (koski & david 1994). this indicates that the smith sound pods belong to an independent population, which also accords with local knowledge. in combination with the reduction of narwhal stocks at inglefield bredning (heide-jørgensen et al. 2002), primarily attributed to unsustainable exploitation, this indicates that the increased catch is not caused by a change in the narwhal distribution. however, it cannot be excluded that a potential increase in stock size has contributed to the increased catch by hunters in siorapaluk, although this is unlikely given the general declining trend in narwhal stocks in greenland for the period (born et al. 1994; heide-jørgensen et al. 2002; heide-jørgensen & acquarone 2002; heide-jørgensen 2004; jcnb/ nammco 2004). as no abundance estimates exist for smith sound, no information is available on sustainable catch levels for this stock. the optimal sustainable use of all greenlandic narwhal populations is imperative, in consideration of the cultural and economic importance of narwhal hunting (sejersen 2001). with the introduction of quotas from july 2004, catches have been reduced drastically, and hunters struggle to find alternative incomegenerating activities. hunting is a central part of greenlandic culture and identity, and the greenlandic hunter’s organization, knapk, has strong political support. the existence of a population of narwhal in smith sound for which scientific recommendations are lacking has been seen as an opportunity to increase narwhal quotas in west greenland. coupled with the effects of climate change, which appear to be accelerating and leading to changes in sea-ice cover earlier than expected (holland et al. 2006; stroeve et al. 2007; serreze et al. 2007), this could have serious detrimental implications for narwhal stocks. the dffl have been attempting to reduce quotas gradually to the scientifically recommended sustainable levels in order to give narwhal hunter’s time to adapt and develop alternative income options. however, in the quota year 2005–06, the home rule government added 50 extra narwhal to the quota of 260 whales recommended by the dffl for west greenland, a number that already greatly exceeded the recommended harvest of 135 whales from the west greenland stock (no recommendation is available for the melville bay stock). in is climate change increasing narwhal catches? m.r. nielsen polar research 28 2009 238–245 © 2009 the author242 december 2006 an additional 100 animals were allotted to the 2006–07 quota of 285 whales. in july 2007, an initial quota of 300 whales was allocated for the quota year 2007–08. the home rule government simultaneously pledged in a press release to develop a plan to reduce quotas to levels in accordance with scientific advice by april 2008. however, the quota for the year 2008–09 was again set at 300 animals, and by december 2008 a plan had not yet been produced. instead, 90 animals had been allocated in addition to the initial quota. in a press release by the home rule government this was justified on the basis of the fact that the hunters had applied for additional whales. on a more positive note, a preliminary analysis of new data indicates a higher abundance of narwhal than has previously been assumed (nammco 2008). scientific recommendations are urgently needed to allow authorities to assign sustainable quotas for the smith sound population of narwhals. to prevent untimely interference by politicians in quota allocation, and to ensure compliance and optimal adaptation to local circumstances, collaborative management agreements should be developed with local hunter organizations. this could ensure local acceptance of regulations, and thus prevent the inclination for politicians to allot extra quotas to show their support for the hunters and gain local popularity and votes. collaborative management could also include a jointly developed monitoring strategy (huntington 2000; russel et al. 2000; harwood et al. 2002). this should, in addition to scientific population counts, use the large and costefficient data potential of systematically recorded quantitative observations from the hunters (kofinas et al. 2001; moller et al. 2004; see also danielsen et al. 2000), who regularly traverse smith sound and other narwhal areas. this would give hunters a valid basis for their arguments in discussions on quota allocations, and could provide biologists with an indirect measure of population trends and other information in the periods between scientific counts (fernandez-gimenez et al. 2006), and would therefore permit rapid management responses to changing circumstances, occurring as a result of climate change for instance. although not unproblematic (richard & pike 1993; collings 1997; kruse et al. 1998; klein et al. 1999; kaplan & mccay 2004; tyrrell 2007; fernandez-gimenez et al. 2008), co-management initiatives could ease a strained relationship between biologists and hunters, who have been in strong opposition since the introduction of quotas in greenland (sejersen 2003). recently, a collaboration agreement was signed between knapk and the greenland institute of natural resources. hopefully this can help ensure that the common goals of large viable populations, and compliance with international agreements that greenland has adopted, are achieved. acknowledgements i want to thank the people of siorapaluk for their hospitality, and the hunter’s organizations and local administration in siorapaluk and qaanaaq for providing information for this study. thanks also to the hunting division of the directorate for fisheries, hunting and agriculture for access to catch statistics and other information, and to kristine laidre, mads peter heide-jørgensen, elmer topp-jørgensen, erik w. born, fernando ugarte and natasja kingod for useful information and comments on earlier drafts of the manuscript. references born e.w., heide-jørgensen m.p., larsen. f. & martin a.r. 1994. abundance and stock composition in inglefield bredning (nw greenland). meddelelser om grønland. bioscience 39, 51–68. bryman a. 2004. social research methods. second edn. oxford: oxford university press. collings p. 1997. subsistence hunting and wildlife management in the central canadian arctic. arctic anthropology 34, 41–56. comiso j.c. & parkinson c.l. 2004. satellite-observed changes in the arctic. physics today 57(8), 38–44. copley j. 2000. the great ice mystery. nature 408, 634–636. danielsen f., balete d.s., poulsen m.k., enghoff m., nozawa c.m. & jensen a.e. 2000. a simple system for monitoring biodiversity in protected areas of a developing country. biodiversity and conservation 9, 1671–1705. dietz r. & heide-jørgensen m.p. 1995. movements and swimming speed of narwhals (monodon monoceros) instrumented with satellite transmitters in melville bay, northwest greenland. canadian journal of zoology 73, 2106–2119. fernandez-gimenez m.e., huntington h.p. & frost k.j. 2006. interaction or co-optation? traditional knowledge and science in the alaska beluga whale committee. environmental conservation 33, 306–315. fernandez-gimenez m.e., hays j.u., huntington h.p., andrew r. & goodwin w. 2008. ambivalence towards formalizing customary resource management norms among alaska native beluga whale hunters and tohono o’odham livestock owners. human organization 67, 137–150. freeman m.m.r., bogoslovskaya l., caulfield r.a., egede i., krupnik i.i. & stevenson m.g. 1998. inuit, whaling and sustainability. walnut creek, ca: altamira press. fowler c., emery w.j. & maslanik j. 2004. satellite-derived evolution of arctic sea ice age: october 1978 to march 2003. ieee geosciences remote sensing letters 1, 71–74. is climate change increasing narwhal catches?m.r. nielsen polar research 28 2009 238–245 © 2009 the author 243 gagnon a.s. & gough w.a. 2005. climate change scenarios for the hudson bay region: an intermodel comparison. climatic change 69, 269–297. gough w.a., cornwell a.r. & tsuji l.j.s. 2004. trends in seasonal sea ice duration in southwestern hudson bay.arctic 57, 299–305. gough w.a., gagon a.s. & lau h.p. 2004. interannual variability of hudson bay ice thickness. polar geography 28, 222–238. harwood l.a., norton p., day b. & hall p.a. 2002. the harvest of beluga whales in canada’s western arctic: hunter-based monitoring of size and composition of the catch. arctic 55, 10–20. heide-jørgensen m.p. 1994. distribution, exploitation and population status of white whales (delphinapterus leucas) and narwhals (monodon monoceros) in west greenland. meddelelser fra grønland. bioscience 39, 135–149. heide-jørgensen m.p. 2004. aerial digital photographic surveys of narwhal, monodon monoceros, in west greenland. marine mammal science 20, 246–261. heide-jørgensen m.p. & acquarone m. 2002. size and trends of the bowhead whale, beluga and narwhal stocks wintering off west greenland. nammco scientific publications 4, 191–210. heide-jørgensen m.p., dietz r. & laidre k. 2005. metapopulation structure and hunt allocation of narwhals in baffin bay. in: nammco annual report. pp. 221–223. tromsø: north atlantic marine mammal commission. heide-jørgensen m.-p., hemmeken n. & hollebeek p. 2002. optælling af narhvaler i qaanaaq kommune i august 2001. (census of narwhal in qaanaaq municipality in august 2001.) teknisk rapport 50. nuuk: institute of natural resources. heide-jørgensen m.p. & laidre k.l. 2004. declining extent of open water refugia for top predators in baffin bay and adjacent waters. ambio 33, 488–495. heide-jørgensen m.p. & laidre k. 2006. greenland’s winter whales: beluga, narwhal and bowhead whale. nuuk: ilinniusiorfik undervisningsmiddelforlag. heide-jørgensen m.p., stern h. & laidre k.l. 2007. dynamics of the sea ice edge in davis strait. journal of marine systems 67, 170–178. holland m.m., blitz c.m. & tremblay b. 2006. future abrupt reductions in the summer arctic sea ice. geophysical research letters 33, article no. l23503. huntington h.p. 2000. using traditional ecological knowledge in science: methods and applications. ecological applications 10, 1270–1274. jcnb (canada–greenland joint commission on conservation and management of narwhal and beluga)/ nammco (north atlantic marine mammal commission) 2004. joint meeting of the nammco scientific committee working group on the population status of narwhal and beluga in the north atlantic and the canada/greenland joint commission on conservation and management of narwhal and beluga scientific working group. 3–6 february 2004. tromsø, norway: north atlantic marine mammal commission. johannessen o.m., shalina e.v. & miles m.w. 1999. satellite evidence for an arctic sea ice cover in transformation. science 286, 1937–1939. kaplan i.m. & mccay b.j. 2004. cooperative research, co-management and the social dimension of fisheries science and management. marine policy 28, 257–258. klein d.r., moorehead l., kruse j. & braund s.r. 1999. contrasts in use and perceptions of biological data for caribou management. wildlife society bulletin 27, 488–498. kofinas g., lyver p., russell d., white r., nielson a. & flanders n. 2001. towards a protocol for community monitoring of caribou body condition. rangifer 14, 43–52. koski w.r. & david r.a. 1994. distribution and numbers of narwhals (monodon monoceros) in baffin bay and davis strait. meddelelser om grønland. bioscience 39, 15–40. kruse j., klein d., braund s., moorehead l. & simeon b. 1998. co-management of natural resources: a comparison of two caribou management systems. human organization 57, 447–458. laidler g.j. 2006. inuit and scientific perspectives on the relationship between sea ice and climate change: the ideal complement? climate change 78, 407–444. laidre k.l. & heide-jørgensen. m.p. 2005. arctic sea ice trends and narwhal vulnerability. biological conservation 121, 509–517. leaper r., cooke j., trathan p., reid k., rowntree v. & payne r. 2006. global climate drives southern right whale (eubalaena australis) population dynamics. biology letters 2, 289–292. lindsay r.w. & zhang j. 2005. the thinning of arctic sea ice, 1988-2003: have we passed a tipping point? journal of climate 18, 4879–4894. lloyd-evans s. 2006. focus groups. in v. desai & d. potter (eds.): doing development research. pp. 153–163. london: sage publications. lusseau d., williams r., wilson b., grellier k., barton t.r., hammond p.s. & thompson p.m. 2004. parallel influences of climate on the behavior of pacific killer whales and atlantic bottlenose dolphins. ecology letters 7, 1068– 1076. maslanik j.m., serreze m.c. & agnew t. 1999. on the record reduction in the western arctic sea ice cover in 1998. geophysical research letters 26, 1905–1908. moller h., berkes f., lyver p.o. & kislaioglu m. 2004. combining science and traditional ecological knowledge: monitoring populations for co-management. ecology and society 9(3), article no. 2. nammco (north atlantic marine mammal commission) 2008. scientific committee. report of the fifteenth meeting. qeqertarsuaq, greenland. 11–14 april 2008. tromsø, norway: north atlantic marine mammal commission. nygård l.a. & topp-jørgensen j.e. 2007. paper on significant trade review: beluga whale, narwhal, atlantic walrus and polar bear. nuuk: hunting department, ministry of fisheries, hunting and agriculture. palsbøll p.j., heide-jørgensen m.p. & dietz r. 1997. population structure and seasonal movements of narwhals, is climate change increasing narwhal catches? m.r. nielsen polar research 28 2009 238–245 © 2009 the author244 monodon monoceros, determined from mtdna analysis. heredity 78, 284–292. parkinson c.l., cavalieri d.j., gloersen p., zwally h.j. & comiso c.j. 1999. arctic sea ice extents, areas and trends, 1978–1996. journal of geophysical research—oceans 104, 20 837–20 856. richard p.r. & pike d.g. 1993. small whale co-management in the eastern canadian arctic: a case history and analysis. arctic 46, 138–143. rigor i.g., wallace j.m. & colony r.l. 2002. response of sea ice to the arctic oscillation. journal of climate 15, 2648–2663. rothrock d.a., yu y. & maykut g.a. 1999. thinning of the arctic sea ice cover. geophysical research letters 26, 3469–3472. rothrock d.a., zhang j. & yu y. 2003. the arctic sea ice anomaly of the 1990s: a consistent view from observations and models. journal of geophysical research—oceans 108, article no. 3083. rothrock d.a. & zhang j. 2005. arctic ocean sea ice volume: what explains its recent depletion? journal of geophysical research—oceans 110, article no. c01002. russel d., kofinas g. & griffith b. 2000. need and opportunity for a north american caribou knowledge cooperative. polar research 19, 117–130. sejersen f. 2001. hunting and management of beluga whales (delphinapterus leucas) in greenland: changing strategies to cope with new national and local interests. arctic 54, 431–443. sejersen f. 2003. grønlands naturforvaltning: ressourcer og fangstrettigheder. (greenland’s nature management: resources and hunting rights.) copenhagen: akademisk forlag. serreze m.c., holland m.m. & stroeve j. 2007. perspectives on the arctic’s shrinking sea-ice cover. science 315, 1533–1536. serreze m.c., maslanik j.a., scambos t.a., fetterer f., stroeve j., knowles k., fowler c., drobot s., barry r.g. & haran t.m. 2003. a record minimum arctic sea ice extent and area in 2002. geophysical research letters 30, article no. 1110. simmonds m.p. & isaac s.j. 2007. the impacts of climate change on marine mammals: early signs of significant problems. oryx 41, 19–26. solomon s., qin d., manning m., chen z., marquis m., averyt k., tignor m.m.b. & miller h. l. jr. (eds.) 2007. climate change 2007. the physical science basis. contribution of working group i to the fourth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. stevenson m.g., madsen a. & maloney e. 1997. the anthropology of community-based whaling in greenland. edmonton: canadian circumpolar institute, university of alberta. stirling i. & parkinson c.l. 2006. possible effects of climate warming on selected populations of polar bears (ursus maritimus) in the canadian arctic. arctic 59, 261–275. stroeve j.c., serreze m.c., fetterer f., arbetter t., meier w., maslanik j. & knowles k. 2005. tracking the arctic’s shrinking ice cover: another extreme september minimum in 2004. geophysical research letters 32, l04501, doi: 10.1029/2004gl021810. stroeve j., holland m.m., meier,w., scambos t. & serreze m. 2007. arctic sea ice decline: faster than forecast? geophysical research letters 34, article no. l09501. tyrrell m. 2007. sentient beings and wildlife resources: inuit, beluga whales and management regimes in the canadian arctic. human ecology 35, 575–586. symon c., arris l. & heal b. 2005. arctic climate impact assessment. cambridge: cambridge university press. witting l. 2005. a model selection based assessment for west greenland narwhals with uncertain stock structure. in: final report. joint meeting of the nammco scientific committee working group on the population status of narwhal and beluga in the north atlantic and the canada/greenland joint commission on conservation and management of narwhal and beluga scientific working group. 13–16 october 2005. nuuk, greenland, october 2005. pp. 15–16. tromsø, norway: north atlantic marine mammal commission. is climate change increasing narwhal catches?m.r. nielsen polar research 28 2009 238–245 © 2009 the author 245 tidal ice dynamics in the area of svalbard and frans josef land n . e . dmitriev, a. y u . proshutinsky, t . b . l 0 y n i n g and t. vlnje * dmitriev, n . e . , proshutinsky, a . yu., l ~ y n i n g , t.b. & vinje. t. 1991: tidal ice dynamics in the arca of svalbard and frans josef land. polar research 9(2), 193-205. this study is part of the soviet-norwegian oceanographic programme (snop) on ice and water dynamics in the region between svalbard and frans josef land. the effects of the movements of water and ice on the ice regime are discussed. due to the scarcity of data, numerical hydrodynamical simulations are used. the tidal ice drift is visualized on satellite images as elliptically shaped traces in the ice fields formed by grounded icebergs. these traces are a result of the joint action of tides. wind and permanent currents. n . e . dmitriev and a . yu. proshutinsky, arctic and antarctic scienr$c research institute. bering st. 38. st. petersburg 199226, u . s . s . r . ; t. b . lmyning and t . vinje. norsk polarinstitutt, p.o. box 158, n-1330 oslo lufrhaun, norway. introduction this study is part of the soviet-norwegian oceanographic programme (snop) on ice and water dynamics in the region between svalbard and frans josef land. the effects of the move ments of water and ice on the ice regime are discussed. due to the scarcity of data, numerical hydrodynamical simulations are used. the tidal ice drift is visualized on satellite images (figs. 1 and 2 ) as elliptically-shaped traces in the ice fields formed by grounded icebergs. the length, form and orientation of the elliptic axis make it possible to determine some important parameters which can accordingly be used for the calibration of the mathematical models. two different methods have previously been used for tidal ice drift estimation. zubov (1945) and legenkov (1968) assumed the ice motion to be determined by the surface currents only. they calculated deformation in the ice cover t o specify the regional and temporal change of the ice con centration. kagan (1968), kheysin & ivchenko (1973), kowalik (1981), and timokhov & khey sin (1987) took into account the additional effects of the ice cover and formulated a coupled model. kagan (1968) considered a three-layer model with near-bottom and near-ice boundary layers, and a central layer where the turbulence was neglected. the lack of knowledge of frictional forces in the central layer prevent us from using this model for studies in the arctic oceans where the frequency of the major tide-generating force m2 is equal or very close to the inertial frequency. kowalik (1981) offered a non-linear two dimensional model, which was based on shallow water theory and coupled with a non-linear ice model. his model took into account the internal shear in the ice cover. this model has been used in this study to simulate the tides and the cor responding ice drift. the ice and weather conditions, the area cov ered by satellite images, and the area covered by the model are all shown in fig. 3. the model the horizontal momentum equation for the water, according to shallow water theory and with the tide producing forces included, is + am’v’u the continuity equation on the integral form is -m2div (:h), a6 at _ the equation of the ice motion is dui + 2fi x ui = -mgve+: ti + f, dt p ( 3 ) 194 n . e. dmitriev el al. ftg. / satcllitc imagc of ice bituatioo on 21 m a y 198x. and the equation for the ice concentration is u . u , are the horizontal velocity vectors of water t is the time variable. c is the horizontal del operator, h is the depth; h = d + t. where d is the equi librium depth of the ocean: is the displacement of the sea surface from its equilibrium position, and ice, is the equilibrium tide: (i is a coefficient which takes into account the effects of increased water mass o n the solid earth. i.e. depression d u e t o higher sea level and uplift d u e t o tide producing forces (the changes of the phases a r e neglected). ( y = 1 is used in the model simulation. is a reduction coefficient, which parametrizes the effect of tidal forces o n a n elastic e a r t h . /3 = 0.69 is used in t h e model simulation. f, is the internal ice friction (forces of interaction between ice floes), m is a scale coefficient for the set approximating the arctic ocean o n t h e stereographic pro jection map. for o u r m a p m = l.oon the north the tidal ice dynamics 195 fig. 2 satcllite imagc of ice situation on 1 june 1988. pole, m = 1.017at latitude 75"nand m = 1.072 at latitude 60"n. pw is the density of water, p i s the surface density of the ice cover where p = plh, s , p,, h, and s, are the density, thickness and concentration of the sea ice respectively; a is the coefficient of the horizontal eddy viscosity , r is the angular velocity of the earth's rotation, g is the magnitude of acceleration due to gravity. the bottom and ice-water stress vectors tb and t, can be expressed by ~b = kbpwuiui, t, = k,pju u,i(u u,) (5) where kb and k, are bottom and ice-water friction coefficients. the equation for the internal ice friction is f, = qv*u, + yvdivu, vp. (6) = (nk,divui if divui 2 0 if divu, < 0 (7) where q and y are the coefficients of bulk and shear viscosity in the ice cover with units in cm2/s, p is the pressure due to the ice compression, k, is the coefficient of compression. we borrowed the fi from the studies of rothrock (1975) and kowalik (1981). 196 n . e. dmitrieu et al. 80’ 20. 40 0” 75 * i i 20 o 40 = region corresponding to satellite photos, figs. 1 and 2. -1 01 0 = isobars, mbr. the tidal ice dynamics 197 t h e model parameters used for the simulation are a = 55555 m grid size, kb = 2 . 6 . bottom friction drag coefficient, ki = 5 . 5 . ice-water friction drag coefficient. a = 10". d m2/s. hi = 250 cm average ice thickness value in the arctic basin, hi = 450 cm average ice thickness value in the canadian sector, hi = 140 cm average ice thickness value in the marginal seas, r ] = l o x coefficient of bulk viscosity, y = l o 8 coefficient of shear viscosity, k, = 10 r ] coefficient of compression. polyakov & proshutinsky (1988) obtained root mean-square errors for the values of the tidal amplitudes and phases, using observed harmonic constants for 94 stations located on the coast and islands of the arctic oceans. these values are 0.054m, 0.023m. 0.013m and 0.014m from amplitudes of the waves m2. s2, k 1 and 0 1 . respectively. t h e standard deviations for the phases a r e 26, 28, 28, 30 degrees, respectively. there is a lack of tidal observations in the region of spitsbergen and frans josef land. most sta tions are situated in the narrow bays or straits far from the open ocean. o n e station. located in the strait between nordaustlandet and kvitaya (aagard e t al. 1983) provides data o n bottom pressure and current records (tables 1 and 2 ) . apparently, the observed harmonic constants for most of the stations do not reflect the real process of spreading of the tidal waves in the ocean (figs. 4 and 5). t h e tidal currents in the fram strait (table 1) are assumed to be more representative and they are in closer correspondence with the calculated values. we observe many features in our cotidal charts (figs. 4 and 5) of waves m2 and k 1 common t o those obtained by gjevik & straume (1989). t h e main differences are related t o the displacement of the amphidromic point of the m2 wave near franz josef land and novaja zenilja. our charts indicate that these points are in the open sea (two grid steps from the coast) while the charts of gjevik & straurne (1989) indicate a location on the coast. the differences are d u e to different grid implimentation. the study of polyakov & proshutinsky (1988) shows that the barents s e a is a good resonater of the semidiurnal oscillations. small differences in boundary and initial conditions at the coasts ( g , ) we have used a no-slip condition, i.e. zero velocities, along t h e coastlines u l g , = 0, u i l g l = 0 (8) along the open boundary (g2) t h e vector of the average velocity must b e known as a function of position and time. let u = (u, v) and u, = (ui, y ) then u(x, y, t)lc2 = a,cos(wt i),) u(x, y , f)lg2 = cos(wt w v ) (9) u,(x, y , t)/g, = '"1 cos(wt w u , ) u,(x, y , t)lgz = a v ~ cos(wt i ) v , ) with the following condition, which means that the water mass and masses of ice a r e conserved in the basin: u, = u sin q + u cos cq. u,, = u, sin a1 + v, cos (y, where n is a normal t o t h e open boundary, w is a frequency of the tidal wave, v,, i),,, i),,, i)v, are the phases of water and ice velocity and a,, a,, a,,, a,, a r e the amplitudes of ice and water velocities, respectively, (y, is the angle between the n and x-axis and d g is an infinitesimal seg ment of g z . w e assumed the system to be initially at rest, u ( x , y . 0) = 0, u , ( x , y, 0) = 0, z(x, y, 0) = 0 at t = 0 (10) and the ice concentration t o be s(x, y, 0) = 0.9 a t t = 0. (11) results in the numerical simulations reported below, we have used the boundary values for a,, i)", a,,, i),,, obtained by polyakov & proshutinsky (1988). equations 1 t o 4 were approximated by a lax-wendroff semi-implicit, central-difference scheme, modified by tee (1976). fig. 3. ice and meteorological situation i n the region on 21.05.88 ( a ) and 01.06.88 (b). 198 n . e . dmitrieo et al. tublr 1 . tidal ellipse parameters in the fram strait. abbre\ations: mod = model results: obs = observations: res = our results. model results are from gjevik (19%)). observations ( f i . f?. f3i arc from aagard et a l . (1985). and (f4) is from aagard et al. (1983) * indicates upper current recordcr; * * indicates near bottom current recorder. the geographical positions of the stations fi. f2. f3 and f4 are +en i n tablc 3. station consistuent major scmiaxis minor semiaxis cmils cm/s mod obs res mod obs res f1 m? k i f2 m? k i f.7 m? k1 f1 m2 f1 k i f4 s2 f4 01 3.3 2 . 5 1.5 1.1 3.6 2 . 5 i .3 1 . 2 2 . 5 2 . 5 i ? i .4 8.6 3.6 1.3 0.9 3.5 1.6 0.5 0.3 3.3 1.7 2.8 1 6 2.4 1 . 5 7 9 1.3 3.2 0.5 0.2 0.4 0.4 0.2 0 . 2 0.2 0.3 0.3 0.2 0.2 0.1 0.1 2.2 2.4 0.1 0.2 1.3 0.7 0.2 0.0 0.6 0.3 0.4 0.0 0.4 0.1 3.4 0.1 1.1 0.3 table 7 . tidal ellipse parameters in the fram strait. ahbrevations: mod = model results; obs = observations; res = our results. model results are from gjevik (1990). observations ( f i . f2. f3) are from aagard et al. (1985). and (f4) is from aagard et al. (1983). azimuth = oricntation in degrees of major axis from north. positive eastward. rotation: positive (+) = anticyclonic; negative ( ) = cyclonic. * indicates upper current recorder: * * indicates near bottom current recorder. station consistuent azimuth degree rotation mod 0 bs res mod ohs res f1 m2 k i f2 mz k i f3 m2 k1 f4 m? f4 k i f3 s? f4 01 i 3 18 1 1 37 10 14 i 19 i6 8 3 6 -6 12 14 27 -1s 5 1 57 ~ 68 10 ~ 14 0 i5 17 6 -8 15 12 i0 + + + + + table i geographical positions of the stations the approximation of depths of coastline between the different models may therefore lead to con station la t lon siderable differences in the cotidal charts. the calculated tidal ice drift (figs. 6 and 7) f1 78"59'n y15'e shows maximum velocities to the south of spits f2 79"w'n 4"z5'e bergen, at depths from 5 0 m to 100m. the vel ocity of the semidiurnal ice drift is in this area about 30 cm/s. the ice velocities caused by the station coordinates 3"18'e 30a00,e f3 78% ' n f4 80"oo'n 0 75 ' a 75 ' the tidal ice dynamics 0' 20 l o 60 ' 80 ' 80 * 0' 40' 20' 40 a ~tidal wave phases = tidal wave amplitude l8 at the stations , 34 = phaselamplitude observed 99 30° 50 ' 80' 60' f i g . 4 phases and aniphtudcs of the m2 ( a ) and s2 (b) tidal waves. zero phase corresponds to the lunar time at the greenwich meridian. phases are in degrees, amplitudes i n cm. 63 152 = phase/amplitude observed by pressure recorder 200 n . e . dmitriev et al. 0' 75 ' 0 75 20' 80' 0" 20" 60' 20 75' 40" __ = tidal wave phases -= tdal wave amplitude -2z = phase/arnplitude observed at the stations frg .i phd5r.s and 'trnplitudcs of the k i ( a ) and 01 ( 8 ) tlddl @go = phaselamplitude observed w a e 5 4mplitudes a r e in cm ' by pressure recorder :0 i0 * 80' 60' the tidal ice dynamics 201 9 1p 2p 3p y c*/s fig. 6 . principal axis of m2 (a) and s2 (b) tidal ice motion ellipse 202 n . e . dmitrieu et al. , ‘ ’ \ i i,--+/ ‘ i / f i i # , i i ‘ i i i i 1 ’ i i i c 0 10 20 30 40 c”/s fig. 7 . prlnctpal axis of the k l ( a ) and 01 ( b ) tidal ice motion ellipse 203 the tidal ice dynamics \ i i i i / i 01.06.88 0 3 6 9krn fig. 8. trajectories of ice motions. a) = observed data where a corresponds to fig. 1 and b corresonds to fig. 2. b) = calciilated results, where ice velocities and the sum of the harmonic tidal wave components m2, s2. k1 and 01 have been used. c) = calculated results as b) plus the influence of wind and permanent currents. 204 n . e. dmitrieu e t a / . 30 20 40 0 -10 -a -3( 4 0 30 20 10 0 -10 2c 3c 4 0 h o u r s event 11. fip. y. the dnergcncc of t h c ice velocities f o r the situation o n ? i ma! lyx8 (event 1 ) and f o r the situation on 1 june 19x8 ( e i e n t i ! ) diurnal k1 wave are greater or equal to the effects of the semidiurnal s? wave. the intensification of the semidurnal ice drift is noticeahle in the area between frans josef land and spitsbergen. the velocities of the net diurnal ice drift is. however. relatively small and possibly directed northwards between spitsbergen and frans josef land. t h e main direction of the maxi mum ice drift deviates from 8 to 30 degrees from the main direction of t h e maximum water vel ocities in the region. now let us discuss the correspondence between the calculated ice drift a n d t h e observed drift (figs. 1 and 2 ) . we will then analyse the character of the ice drift and specify t h e ice and nieteoro logical conditions. the tidal ice dynamics 205 the sign of the divergence changes from positive t o negative with a variable period from 4 t o 16 hours. t h e channels in the ice cover can exist only when the divergence is positive. if the divergence is negative, the channels will b e closed. intensive freezing may prevent t h e channels from closing, but this is unlikely t o occur in may and june, the months when the satellite pictures where taken. it would be valuable t o analyse similar satellite pictures from t h e winter (freezing) season. accordingly, performed simulations may at least qualitatively explain the formation of the regu larly formed channels in t h e ice cover caused by grounded icebergs. o n 21 may (fig. 1) the ice concentration was 9-10/10. t h e ice border was well-defined and the ice was in a compressive condition because of normal directed, on-ice winds. in this situation, apparently, there were no discernible wind induced movements of the ice cover. t h e orien tation of the most elliptical trajectory was parallel to the ice border. t h e average length of the major axis was 5.8 km and the minor axis about 3.9 km. the trajectories of the ice drift were unclosed with a small distance from the beginning to the end of the track. if we assume that the semidiurnal tidal icedrift prevailed in this region, then the average permanent current velocity must have been equal t o 4 c m / s and directed t o the west. this current may be related with the general anticyclonic circulation of t h e seawater around spitsbergen. fig. 8a and b show (a) observed trajectory, (b) calculated trajectory with only the tidal forces included in the model, and (c) cal culated trajectory with tidal forces, the wind and permanent current included. t h e model cal culations a r e carried out for two tidal periods. this explains why there are two loops in the model results (fig. 8 a ( b ) , b(b), and b(c)) and not in the observations (fig. 8 a ( a ) and b(a)). t h e trajectories a r e obtained by using current hourly values from the model calculations t o cal culate the particle displacement. nilsen e t al. (1990) employed a simular procedure, using cur rent measurements averaged over a period of 30 minutes. fig. 8a reveals that good correspondence between the model calculation and observations is obtained by using all tidal waves together with the wind and the permanent current influence. modelled ice drift trajectories for 1 june are shown in fig. 8 b(b) and (c). t h e wind and ice conditions a t this date differ from the event discussed above. t h e concentration of ice is about 7-y/10 and the wind blows in a southwesterly direction, coinciding with the direction of the permanent current. t h e trajectories of the ice movements are therefore elorigated. t h e major axis is now about 15 k m , which corresponds well with the observed trajectories (fig. 8 b(a)). the consequence of the joint action of tides, wind and permanent current creates the periodic formation of loops. t h e twice diurnal divergence and compression (fig. 9) may explain why the tracks of ice movement live for only 12-13 hours. references aagard. k.. foldvik. a., g a m m e l s r ~ d , t . & vinje, t . 1983: one-year records of current and bottom pressure in the strait between nordaustlandet and kvitoya, svalhard. 198c-1981. polar research 1(2), 107-113. aagard. k., darnall. l . , foldvik. a. 6t t ~ r r e s e n , t . 1985: fram strait current measurement5 1984-1985. report no. 63. dept. of oceanography, university of bergen. gjevik, b. 1990: model simulations of tidcs and shelf waves along the sbelvcs of the norwegian-greenland-barents sea. i n davies. a . m. (cd.): modelling marine systems, ool. i crc press inc. gjevik, b. & staume. t. 1989: model simulations of the m and k tide in the nordic seas and the arctic ocean. tellus 41a. 73-96. kagan. b. a . 1968: hydrodynamical tidal mouementc. in the sea. hydrometeoizdat. 219 pp. (in russian). kheysin. d . e. & ivchenko. b. 0. 1973: a numerical model of tidal ice drift with thc interaction between flocs. i z o . arad. sci. ussr: atmosplteric and oceanic plfvsics 9, 42&429 (in russian). kowalik. z . 1981: a study of the m2 tide in the ice-covered arctic ocean. modelling. identification and control 2. 201 223. legenkov, a . p. 1968: on the definition of ice concentration. dispertion and compaction using tidal currenta. a a ri lssue 285, 215-222 (in russian). nilsen. j. h . , mcclimans. t. a. & l0vis 1990: rift drift in floe flow: ice-berg wakes in arctic sea ice. continental shelf research l o ( 1 ) . 81-86. polyakov, i. v. & proshutinsky, a . yu. 1988: periods of the eigcnoscillations of sea level i n the arctic ocean. mereor ologia and hvdrologia 11. 91-100 (in russian). rothrock, d . a . 1975: the mechanical behaviour of pack ice. a n n . reu. of earth and planetary sci. 3. 317-342. tee. k. t. 1976: tide-induced residual current, a 2-d nonlinear numerical tidal model. journal of marine research 34. 603 628. timokhov, l. a . & kheysin, d. e. 1987: dvnamics ofrhe sea ice. hydrometoizdat. leningrad. 271 pp. (in russian). zuhov. n . n. 1945: arctic ice. izd. glavsevmorputi. moscow. 350 pp. (imrussian). terrace scarp deflation as a renewable source for eolian sediments in an arctic periglacial setting k e e n e s w e l t a n d keith m a n n swett k. & mann k., 1986: terrace scarp deflation as a renewable source for eolian sediments in an arctic periglacial setting. polar research 5 n . s . . 45-52. glacial, glaciofluvial, and glaciolacustrine sediments deposited by the retreating vibekes glacier are being actively reworked into sand dunes and loess sheets o n the tops of glaciofluvial terraces down valley from vibekes glacier and vihekes s 0 . active permafrost precludes trenching below 0.5 to i .0 meters. however, sedimentary structures, deflationary and abrasion features in shallow and surface deposits are visible. although an armored pavement inhibits sediment deflation on the horizontal terrace surfaces, a combination of fluvial erosion, mass-wasting, and eolian processes o n terrace scarps provides a continuing source of sandand silt-size materials for redeposition. keene swert and keith mann. department of geology, the universiry of iowa. iowa cit-v. iowa, u.s.a. februar), i986 (revised september 1986). introduction periglacial environments have frequently been cited as contributory or pivotal to the generation of pleistocene and older eolian deposits (tuck 1938; cailleux 1942; fristrop 1952; pewe 1955; smalley 1966; selby, rains & palmer 1974; nies sen et al. 1984). however, few studies have docu mented modem eolian processes and their sedi ments actively forming in periglacial environ ments. although small in areal extent ( < 10 km2), the accumulating sand dunes and loess deposits on the terraces of vibekes elv (river) provide a modem example of eolian processes and their deposits. the sand and loess deposits described here are accumulating 10-20 km southeast of the present front of vibekes glacier in northern hudson land in central east green land at 74'5" and 23"w (fig. 1). vibekes s0 (lake) is adjacent to the terminus of vibekes glacier. vibekes elv flows from the lake and courses down valley through glacial, glacio fluvial, and glaciolacustrine deposits. numerous terraces occur at various heights on both sides of the river with the uppermost terrace being 150-200 m above the present river level. the terraces are marked by their unusually flat upper surfaces (fig. 2). cowie & adams (1957) briefly described these terraces. approximately 25 km downstream from the outlet of vibekes s0, vibe kes elv converges with a valley occupied by wordies glacier. northwesterly winds coming down-valley off the greenland ice sheet pre dominate, although we occasionally observed up-valley southeasterly winds during our two week stay in the valley. description of the terraces in this relatively short valley (25 km), vibekes elv has entrenched 150 to 200 m through glacial, glaciofluvial, and glaciolacustrine deposits. the glacial, glaciofluvial, and glaciolacustrine sedi ments that form the terraces consist of sorted and poorly sorted clayto boulder-size materials. these sediments are mostly unconsolidated, al though there is slight competency to the glacio lacustrine silt beds. the cobbleto boulder-sized material in these terraces is well to very well rounded. approximately 35 km2 of unconsoli dated sediments at the angle of repose ( = 30") are exposed along the terrace scarps. (calcula ted, assuming: (1) an approximate average relief of 175 m between the valley floor and the top of the upper prominent terrace, and (2) approxima tely 100 km of terrace scarp surfaces along the meandering path of vibekes elv and its tributari es.) description of the eolian deposits two genetically distinct types of eolian deposits 46 -----, / hudson land 24" 23" fig. /. map of a portion of central east greenland showing geographic relations of hudson land, the vibekes glacier. vibekes so (lake), vibekes elv (river) a n d wordies glacier. insert shows locality of area in east green land. exist within the vibekes elv valley: wind shadow, 'cliff dunes and vegetative-baffled loess sheets. the cliff dunes are visually more prominent, but the loess sheets are probably more significant volumetrically and areally. hobbs (1931) also observed these two types of deposits in southeast greenland. the cliff dunes range i n size from a single large longitudinal dune nearly 0.75 km in length, 100 m wide and 20 m high (fig. 3) to minor sand 'drifts' behind vegetated tufts (fig. 4), or behind large boulders and cobbles. the larger dunes, restricted to terrace margins adjacent to the angle of repose scarps. appear to result from vertical eddies formed where the wind currents transport sand up the scarps shear at the horizontal terrace tops. sedimentary structures of the sand dunes in clude large-scale cross-bedding (larger than the access of o u r permafrost-limited excavations), ripples (figs. 5 and 6) and surface scours (fig. 7 ) . two surprises emerged from the excavations made to observe internal sedimentary structures in the dunes: ( 1 ) cross-bedding on the up-wind, erosional side of the dunes (except for a thin veneer < 1 cm) was inclined at an angle consis tent with the slip face on the lee side of the dune (fig. 8), and (2) the existence of a 25 cm thick, tabular bed of snow lying 18 cm beneath the surface, but above the permafrost surface on the lee side of the largest dune (fig. 9). the volume and distribution of snow and ice layers deeper within the dune is an interesting subject for spe culation, but further investigation would require equipment more persuasive than our folding shovels to excavate through the permafrost. slump structures on the surface of many dunes may result from melting or sublimation of such snow or ice layers within the dunes. this process should be considered as a potential cause of erra tic internal structures within periglacial and per haps northern temperate zone dune deposits. similar snow layers a n d associated slumping structures have been observed elsewhere in 47 fig. 2. photo looking northwest up the vibekes elv valley showing the prominent and flat upper terrace level and the angle of repose scarps to present river level. here the terrace is approximately 150 meters above river level. some bedding within the fluvial terrace gravels can also be seen. fig. 4. view of small sand ‘drifts’ to the lee of vegetated tufts. entrenching tool handle is 50 cm long. arrow indicates principal wind direction. modern sand dunes (selby, rains & palmer 1974; ahlbrandt & andrews 1978; ahlbrandt & fryberger 1982), but perhaps have been over looked as the cause of contorted or slumped bedding structures in ancient eolian deposits. size-frequency distributions over the surface of the sand dunes are so variable that their analy ses are judged to be non-significant. of signifi cance, however, are observations of the grain shapes on the dune surface. the sands were sepa rated into 1/2 phi class intervals, and the only grains on the stoss or lee sides of the dunes to show any degree of rounding were those larger fig. 3. view across the upper terrace in the vibekes elv valley looking to the southwest. in the distance i s the largest of the observed dunes, approximately 20 m high, that sits on the edge of the erosional bank of the terrace. closer to the photographer is a smaller longitu dinal dune 2-3 rn high. than 0.125 mm; these were subangular. all o f t h e grains smaller than 0.125 mm were angular to very angular. this may reflect the relatively short distance of fluvial and eolian transport and hence opportunity for abrasion, or may merely reflect the lesser susceptibility of smaller grains t o abrasion (kuenen 1960). the loess sheets, comprised principally of silt-size detritus, are mainly deposits trapped by tufted vegetation (species of dlyas and silene constitute the major vegetative tuft builders o r ‘bunch plants’). tufted vegetative surfaces (fig. 10) occupy a consider able portion of the upper terraces and thus must trap volumes of loess far exceeding the sediment volume of the cliff dunes, albeit in a less con spicuous fashion. at one locality where a tribu tary stream dissected a loess deposit we observed 1 to 1.5 m of structureless loess, although some mottling and irregular fermginous o r organic staining boundaries were apparent within the loess (fig. 1 i ) . we also observed lemming bur rows on the surface, but did not see evidence of burrowing exposed in the cuts. surficial tracks of musk oxen, fox, and birds abound, but preser vation of these structures would be an unlikely event. wind blown sand often fills the polygonal desiccation cracks that commonly exist between vegetative tufts. surficial mud cracks are also present in several non-vegetated areas on the terrace surface, particularly adjacent t o the small ponds. 48 figs. 5 and 6. views of dune surface showing ripple marks of two different sizes. entrenching tool handle is so cm in each photo. fig. 7. a granitic cobble o n the edge of the dune with a wind scoured excavation on the stoss (right) side. scale beneath the scour structure in the photo is 3.5 cm wide. the granitic cobble is polished and incipiently fluted by sand abrasion. i t also exhibits minor exfolia tion on its upper surface, perhaps due to feldspar expansion during weathering. arrow indicates princip al wind direction, less significant are deposits of silt-sized mate rials trapped in the small ponds that have formed either as kettle lakes or as abandoned channels on the terrace surfaces. that this sediment is actively accumulating was confirmed by the ease with which the fine sediment was stirred into suspension during a brief excursion into one of the ponds t o bathe. deflation and abrasion features a deflated and abraided armored pavement (fig. 12) veneers virtually all of the terrace surfaces that are not covered by low vegetation (comm only clumped as 'bunch plants') or covered by water (the small ponds in abandoned channels or kettles). in a similar environment in southeast greenland, hobbs (1942) reported the deflation of dust, sand and smaller pebbles from outwash plains to form an armor of pebble pavement that protected the materials below from further defla tion. in areas of active eolian sand transport, the pebbles, cobbles, and boulders exhibit highly polished surfaces and often show preferential removal of weathered rinds on the windward (generally up-valley) side (fig. 7). many of the rounded cobbles and boulders on the terrace surface show in situ frost shattering (fig. 13) that produces modifications of clast shapes on the surface. examination of cobbles and boulders buried within the terraces indicates that the frost shattering occurs only on the upper surface of the terraces and not within the buried gravels. facet ing, fluting, and polishing of the pebbles, cobb les, and boulders on the armored pavement are common and well developed. limestone clasts exhibit the highest degree of faceting and fluting, but even granite (fig. 14) and quartzitic cobbles show discernible fluting. we observed multi faceted wind-polished and fluted cobbles. it is unclear whether eolian abrasion generated the facets, or if merely eolian abrasion of fracture formed facets produced them. an interesting type of eolian faceting, though of dubious geological significance, occurs where clumped vegetation (bunch plants) has trapped eolian sediments. erosion of these clumps has produced 'facets' on their stoss sides much like the cobbles and boulders elsewhere (fig. 15). geomorphic processes and hypotheses of dune formation in the vibekes elv valley although vibekes elv presently flows along the southwest flank of wordies glacier to the fjord 49 fig. 8. cross-bedding in the slip-face of a dune that is parallel or sub-parallel to the surface of the dune. painted dark and white intervals on the monopod are 10 cm each. fig. 10. view of irregular tufted vegetation on the upper terrace. the ‘bunch plants’ serve as an effective baffle to trap silt-sized sediment over large areas of the terrace. individual tufts are approximately 10 cm high. fig. 9. excavation into the slip face of the largest dune that exposes a tabular snow layer 25 cm thick beneath i8 cm of sand. bedding structures within the snow as well as the sand indicate that both the snow and the sand were prograded by eolian deposition on the lee side of the dune. thin sand laminae within the snow further suggest that at the time the snow was being added to the dune, the snow cover was probably relati vely thin so that both snow and sand surfaces were being deflated. fig. 11. scraping of an erosional bank in the loess reveals faint irregular and cross-cutting ?liesegang color mottling. some of the organic or ferruginous stains cross-cut faint bedding planes. at wordies bugt, the terraces and lacustrine sedi ments observed in the lower vibekes elv valley offer convincing evidence that vibekes elv was, at one time, dammed by the wordies glacier to form a lake. this lake not only caused deposition of the glaciolacustrine sediments seen in the lower portions of the valley, but persistent lake levels, determined by the wordies glacial dam, were also apparently the base level control for the prominent glaciofluvial terraces throughout the valley. ephemeral standstills and periodic lowering of the wordies glacial dam appear to have produced the prominent upper terrace and several minor terrace levels (fig. 16). thick glacial, glaciofluvial, glaciolacustrine and tributary fan deposits composing the broad terraces in vibekes elv constitute the immediate provenance for the modern eolian deposits. the ultimate bedrock source of the sediments is glacial and fluvial erosion of a diverse suite of igneous, 50 metamorphic and sedimentary rocks of archean, proterozoic, and phanerozoic age. schists, slates, phyllites, granites, gabbros, dolerites, sand stones, conglomerates, cherts, limestones, and dolostones are all prominent lithoclast types in the cobbleto boulder-sized detritus of the terraces. katabatic winds that cascade southeastward down from the greenland ice sheet (fig. 17) are reworking the finer-grained terrace sediments into cliff dunes and loess sheets. the cliff dunes appear to result from both vertical and horizontal wind eddies with steady progradation and pro gressive thickening of the eolian sand deposits through time. the derivation of eolian sediments from poorly sorted glacial and periglacial precursor sedi ments poses an enigma. the eolian deposits or a densely packed lag deposit of pebbles, cobbles and boulders (i.e. an armored surface) veneer the upper terrace surfaces. therefore, except for reworking, the upper surfaces of the terraces cannot now be providing a sediment source for the eolian sand and loess. i n this setting, modern deflation processes acting on the terrace gravels would seem t o be self-inhibiting because of the armored pavement. periodic advance and retreat of the glaciers might expose fresh surfaces of unwinnowed materials, but would readily erode the unconsoli dated materials in the valley and, almost certain ly, would rework and modify the eolian deposits beyond recognition. the outlet of vibekes sb appears to be morainally dammed with no discernible outwash that might serve as a source of sand and/or loess. direct observations of the processes currently operating in the valley of vibekes elv, however, offer fresh insight into a renewable source of deflatable sandand silt sized sediments. during our stay in the valley, the suspended air-borne sediment was often so thick as to obscure visibility, and near the terrace scarps the saltating sand was intolerable. of tangential interest during these dust storms was that, if the day was sunny, one could observe the reflections of light from the cleavage planes of fine micas (mainly muscovite) that were suspended in the air. fluvial erosion of the thick gravel deposits by the present course of the vibekes elv has produced vast exposures of angle of repose gravel slopes adjacent to the river. as wind deflates the finer particles (sand, silt, and clay) from these angle of repose surfaces, the pebbles, cobbles, and boulders roll downslope and accumulate at the base of the slope rather than remaining as a lag on the steeply inclined surfaces. cowie & adams ( l 9 5 7 ) , referring to material cascading down these slopes, stated that it includes ‘large boul ders which, in the spring, can bowl at speed across the frozen river to the diversion of those who use it for sledging’. to an observer standing on the terrace cliff edge during the strong kata batic wind storms there is little doubt that sand-, granule-, and pebble-sized materials are being transported up the scarp faces and onto the upper terrace. meandering and lateral cutting by the river at its erosional level remove the coarse clasts from the bases of the slopes, and the pro cess continues to slowly broaden the valley floor. thus, the combined processes of lateral cutting by the river and mass wasting of the coarse detri tus down the angle of repose slopes generate renewable a n d abundant sources of deflatable detritus to form the eolian deposits of vibekes elv. summary and conclusions i n the periglacial valley of vibekes elv i n northern hudson land, central east greenland, retreat of the vibekes glacier, probably during the last 6000 years, coupled with damming of the valley by a convergent glacier has left thick depo sits of glaciofluvial and glaciolacustrine sedi ments as prominent terraces on either side of the valley. deposition and subsequent incision of these terraces by the river have produced vast areas of angle of repose slopes that are subject to deflation by present day katabatic winds. the deflated material derived from these scarps is being redeposited both as sand dunes and as vegetative-bound loess deposits on the tops of the terraces. the observed complimentary mechanisms of fluvial erosion, mass wasting, and deflationary processes acting on these scarps provide a constantly renewable source of fine sediment. the horizontal surfaces of the terraces are inhibited from deflation by the armored pavements. 5 1 fig. 12. surface of the terrace in a deflated area show ing the coarse desert pavement of mixed lithologies. fluting and polishing of the pebbles and cobbles are apparent. scale at lower right is 3.5 cm wide. fig. 15. eolian faceting of a vegetative tuft. the consis tent orientation of these ‘facets’ indicates that they are the product of eolian abrasion. height of tuft is approximately 15 cm. arrow indicates principal wind direction. fig. 13. photo of a partly buried dolomitic siltstone on fig. 16. view across vibekes elv showing the multiple the upper terrace surface showing in situ frost shattererosional terrace levels formed during ephemeral ing of the cobble into flakes parallel to the bedding. ‘stand-stills’ in the lowering of the glacial dam at the scale at upper left is divided into cm. confluence of the vibekes elv and the wordies glacier. fig. 14. a partly buried granitic cobble on the fig. 17. photo across the vibekes elv valley on a mildly deflation surface of the upper terrace showing fluting windy day showing the wind-born sand and silt moving of the stoss side by eolian abrasion. scale is 17 cm long. from right to left down-valley (southeastward). at arrow indicates principal wind direction. times the sediment cloud reached heights of several hundred meters. arrow indicates principal wind direc tion. 5 2 the integration of c o m p l e m e n t a r y erosional and mass-wasting processes t o p r o v i d e a mechanism for g e n e r a t i n g continually d e f l a t a b l e s e d i m e n t s merits c o n s i d e r a t i o n as a n e x p l a n a t i on for o t h e r modem, pleistocene, or o l d e r peri glacial eolian deposits. acknowledgements. the observations recorded here were made during an expedition to east greenland supported by n.s.f. grant dpp-84-41584. we appre ciate the careful editorial reviews of the paper by timothy kemmis. sherwood tuttle, and ian smalley. references ahlhrandt, t. s. 8( a n d r e w . s . 1978: distinctive sedi mentary features of cold climate eolian deposits, north park, colorado. paleogeographr. paleoclima ro1og.r. palt=oecologjzs.327--35 1. ahlbrandt, t. s. & fryberger. s. g. 1982: introduction to eolian deposits. pp. i 1 --47 in scholle. p. a. & spearing, d. (eds.): sandstone depositional environ nienfs. .4merican .4ssociation of petroleum geologists. mrmoir 31. cailleux, a. 1942: les actions eolians periglaciaires en europe. societe geologique france, memoire 46. 176 pp. cowie, j . w. & adams, p. j. 1957: the geology of cambro-ordovician rocks of central east green land. meddr. grenland 153. fristrop, b. 1952: wind erosion within the arctic deserts. geogr. tidsskr. sz. 5 1 -65. hohbs, w. h. 193 1 : loess, peddle bands and boulders from glacial outwash of the greenland continental glacier. joumalqfceology 39.381 -385. hobbs. w. h. 1942: wind-the dominant transporta tion agent within extramarginal zones to continental glaciers. journaloj'geologp so. 556-559. kuenen, p. h. 1960: experimental abrasion 4: eolian action. journalof geology 68,427-449. niessen, a. c. h. m.. koster, e. a. & galloway, j. p. 1984: penglacial sand dunes and eolian sand sheets: an annotated bibliography. department of the inferior. u . s . geological survqr openlfile report. 84167. pewe. t. l. 1955: origin of upland silt near fairbanks, alaska. geol. soc. ofamerica bull. 66,699-724. selby. m., rains, r. b. & palmer, w. p. 1974: eolian deposits of ice-free victoria valley, antarctica. new zealand journal of geology and geophjric.7 17. 543-562. smalley, i. j. 1966: the properties of glacial loess and the formation of loess deposits. journal ojsediment a n . petrology 36,669-676. tuck, r. 1938: the loess of the matanuska valley, alaska. journalof geology 46.641 -653. no job name r e s e a r c h n o t e por_123 426..432 pleomorphism in the antarctic flagellate pyramimonas gelidicola (prasinophyceae, chlorophyta) john van den hoff & john m. ferris† australian antarctic division, 203 channel highway, kingston 7050 tasmania, australia †deceased abstract species of the genus pyramimonas (prasinophyceae) are a common, widespread, but minor component of the antarctic marine phytoplankton. they are often associated with the seasonal sea-ice environment. pyramimonas gelidicola (mcfadden, moestrup & wetherbee, 1982) was isolated from the water column of a saline antarctic lake, and observations on the organism’s life history as it grew in unialgal cultures were made. the alga proved to be pleomorphic: capable of producing several morphologically distinct life stages. we recorded motile single-celled quadriflagellates that formed two statistically distinct size classes, a rare uniflagellate cell-type, and aggregations of quadriflagellate cells, multilobed forms and an encystment stage. multilobed forms and cell aggregations, never before observed in an antarctic pyramimonas species, are presumed to be growth medium-induced morphotypes. multilobed forms contained an equal number of nuclei and lobes, suggesting that they are the product of asexual reproduction. some of the morphotypes we report here may never be observed under natural field conditions, but the potential for this alga to alternate between morphotypes is clearly demonstrated. keywords antarctica; life history; pleomorphism; prasinophyceae; pyramimonas. correspondence john van den hoff, australian antarctic division, 203 channel highway, kingston 7050, tasmania, australia. e-mail: john_van@aad.gov.au doi:10.1111/j.1751-8369.2009.00123.x the green algal genus pyramimonas schmarda, 1850 is well represented in polar waters (daugbjerg & moestrup 1993). from antarctic waters, mcfadden et al. (1982) first described pyramimonas gelidicola (prasinophyceae) after it was isolated from sea-ice samples taken in prydz bay, and water samples collected at rookery lake and ace lake in the vestfold hills, east antarctica. since then, two more species, pyramimonas tychotreta (daugbjerg, 2000) and pyramimonas australis (moro et al., 2002) have been described from coastal antarctic waters. the life cycles of the known antarctic pyramimonas species currently include an encystment stage for p. gelidicola (van den hoff et al. 1989; daugbjerg et al. 2000) and a uniflagellate stage that daugbjerg et al. (2000) considered to be a gamete of p. tychotreta. the formation of a resistant, cyst stage was presumed to be a response to environmental stress, but recently daugbjerg et al. (2000) found germinating cysts and encysting cells co-occurring in field samples, leading them to suspect that no single abiotic factor regulated the formation of those stages. the environmental stimuli required to germinate cysts remains unknown for several pyramimonas species (belcher 1969; van den hoff et al. 1989), but in others a return from darkness to a low light regime and fresh media triggered excystment (hargraves & gardiner 1980; aken & pienaar 1981). an additional life stage, a multilobe form (termed pleomorph cells by aken & pienaar 1981) has been observed for two pyramimonas species: pyramimonas amylifera and pyramimonas parkeae (hargraves & gardiner 1980; aken & pienaar 1981). multilobed stages are most probably a culturally induced stage, having never been reported from the wild, and their frequency of occurrence in culture seems to be temperature dependent (hargraves & gardiner 1980). individual lobes possess a complete set of flagella and have been seen breaking away from the main cellular mass, suggesting that the stage is implicated in the regeneration of the vegetative cell type (hargraves & gardiner 1980). autogamy may take place within the structure (hargraves & gardiner 1980), but this remains unconfirmed. polar research 28 2009 426–432 © 2009 the authors426 mailto:van@aad.gov.au here, we report on different morphotypes produced by p. gelidicola in culture, discuss the morphological and functional similarities with other pyramimonas species and propose an in vitro life cycle for the species. materials and methods the sample collection, cell culture and microscope observation methods for the investigation of p. gelidicola cells from ace lake, antarctica, have been detailed previously in van den hoff et al. (1989). the culture material upon which the previous study and this study were based no longer exists, but the ace lake strain of p. gelidicola is held at the csiro marine and atmospheric research microalgae supply service. cell dimensions were measured with an eyepiece graticule, and cell sizes (mm) are expressed as means � standard deviations. cellular nucleic acids were stained with the fluorochrome 4′,6-diamidino-2phenylindole (dapi) at final concentrations of 0.2 mg ml-1 for glutaraldehyde-fixed samples, and at 1–2 mg ml-1 for living material (coleman 1985). dapi-stained cells were viewed using a pm2 spectrophotometer (carl zeiss, oberkochen, germany) with uv epifluorescence excitation (g365 exciter filter, ft395 dichroic beam splitter and a lp420 barrier filter). results pyramimonas gelidicola produced a number of distinct morphotypes when grown under identical environmental conditions in either f/2 or gp growth media (fig. 1). quadriflagellate cells we observed two different-sized motile quadriflagellate cell types: a small cell type and a larger, rounder cell type (fig. 1a). the small cells measured 12.0 � 1.2 mm in length, and 9.9 � 0.8 mm in diameter (n = 13); each cell had four flagella, and appeared to contain a central pyrenoid and lipid inclusions surrounding the flagella depression. the larger cells were rounder, measuring 15.7 � 2.5 mm in length and 14.2 � 2.5 mm in diameter (n = 17). student’s t-test comparisons of the means showed that these cell types formed two distinctly different size classes (cell length, t-value = -4.93, d.f. = 28, p < 0.001; cell width, t-value = -5.80, d.f. = 28, p < 0.001). dividing cells (fig. 1b) had two sets of four flagella and two pyrenoids. cell division began at the flagella depression, and continued until the cells remained joined only at the posterior end (fig. 1c). uniflagellate cells (fig. 1d) cells possessing only a single flagellum measured 12.6 � 0.7 mm in length, and 10.2 � 0.3 mm in diameter (n = 5). these cells contained an enlarged starch reserve and numerous lipid droplets dispersed throughout the apical half of the cells. a single flagella with a terminal swelling (perhaps induced by the fixation procedure) emerged from an apical depression. this cell type was rare, and therefore no scanning electron microscope (sem) or transmission electron microscope observations could be made to determine whether scales were present on the periplast and flagella. cell aggregations (fig. 1e) aggregations of usually four, but sometimes up to eight, very closely associated single-celled quadriflagellates were observed. unlike the multilobed stages (described below), each cell within the aggregation retained its own integrity. cell aggregations were very active, beating their flagella rapidly. multilobed forms (fig. 1f, g) multilobed forms had between three and eight lobes. a common periplast surrounded the mass, and each lobe had four active flagella. eight-lobed forms consisted of two, four-lobed forms joined by an isthmus (fig. 1g). this morphotype had a covering of periplast and flagella scales that are typical of the motile quadriflagellate (fig. 1f), thereby confirming they were a product of the quadriflagellate cell. the eight-lobed example shown in fig. 1g lacks scales, perhaps as a result of individual differences in fixation. single motile cells were observed (but not photographed) in live culture during the process of budding from multilobed masses. nuclear dna staining (dapi) revealed that a single nucleus was present within each lobe, perhaps indicating that nuclear division had taken place within the mass, or that a number of quadriflagellate cells had fused. unfortunately, only drawings were made of this aspect of the study, and so no photographs are presented here. the nuclei in deeply invaginated forms were most often located nearer the flagella pits, but were more central in rounder forms, suggesting that these forms were at a different stage of cell division compared with the deeply invaginated forms. on one occasion, a four-lobed form was seen (and drawn) with a thick cyst-like wall within a thinnerwalled membrane. dapi staining showed that the cell contained a single distinct nucleus and a separate dispersed region of dna. pleomorphism in pyramimonas gelidicolaj. van den hoff & j.m. ferris polar research 28 2009 426–432 © 2009 the authors 427 pleomorphism in pyramimonas gelidicola j. van den hoff & j.m. ferris polar research 28 2009 426–432 © 2009 the authors428 cysts (fig. 1h, i) light micrographs (lms) revealed thick-walled cysts contained varying numbers of starch grains and numerous lipid droplets (fig. 1h). cysts were spherical (ø = 17.2 � 3.4 mm, n = 23), and sem showed a covering of spine-scales (fig. 1i), consistent with a previous study (van den hoff et al. 1989). discussion as a first point of discussion it is important to affirm that the morphotypes we report here are life stages of p. gelidicola and no other species. the water samples from which the culture material originated were collected from ace lake, a well-studied antarctic saline lake (e.g., burch 1988; laybourn-parry et al. 2002; bell & laybourn-parry 2003) known to contain a cyst-producing quadriflagellate species described as p. gelidicola (mcfadden et al. 1982; van den hoff et al. 1989). the unialgal cultures used in this study have been confirmed to contain p. gelidicola (van den hoff et al. 1989). the presence of box, crown, limulus and pentagonal scales on the periplast and flagella of a multilobed stage (fig. 1f) lends support to this identity of the species, and also indicates that the multilobed form is the product of p. gelidicola itself. pyramimonas gelidicola has the capability of producing several morphologically distinct life stages (i.e., pleomorphism), albeit under enrichment culture conditions. the cultures contained morphotypes that have never before been observed in antarctic pyramimonas species, but which have previously been reported for other pyramimonas species (table 1). changes in growth culture conditions over time (e.g., nutrient depletion) possibly stimulated the occurrence of these life stages, so perhaps they may never be observed under natural field conditions. however, the encystment stage seen in culture has been observed from field collections (fig. 1i; van den hoff et al. 1989). three species isolated from antarctic waters (p. gelidicola, p. tychotreta and p. australis) are known to produce an encystment stage (table 1). the cysts of p. gelidicola and p. tychotreta are barely distinguishable from each other: both are round, have a thick tri-layered cell wall and have a covering of spiny cyst scales that differ from the quadriflagellate cell type (van den hoff et al. 1989; daugbjerg 2000). the pyramimonas cyst formation began with the motile single-celled quadriflagellate (van den hoff et al. 1989; daugbjerg 2000; moro et al. 2002), but cysts could also be the product of the multilobed stage observed in culture, because we saw on one occasion a multilobed form containing a thickened internal cyst-like fig. 1 light micrographs (lms) and scanning electron micrographs (sems) of the morphologically distinct life stages observed in growth cultures of the antarctic prasinophyte pyramimonas gelidicola. scale bars: 10 mm; except in (f), 1 mm. (a) nomarski lm of glutaraldehyde-fixed small (t-cell) and large (l-cell) quadriflagellate cells. note the enlarged starch reserve in the central l-cell (white arrow) compared with the smaller t-cell (black arrow). (b) phase contrast lm of a living dividing quadriflagellate cell. cell division has begun at the anterior (flagella) of the cell. according to mcfadden et al. (1982), the refractive bodies (white arrow) lying within the flagella collar are lipids. (c) nomarski lm of a glutaraldehyde-fixed dividing cell still joined at the posterior end. a further incomplete division at this stage could produce the pleomorph cell type shown in (f). (d) nomarski lm of a uniflagellate cell type. note the starch (s) and lipid (l) droplets, similar to those seen in the encystment stage (h). the swollen flagella tip (arrow) is likely to be an artefact of sample preparation. (e) nomarski lm of an “aggregation” of four quadriflagellate cells. (f) sem of a four-lobed stage possessing a near full complement of four flagella in each flagella pit. the periplast has a covering of body (black circle) and crown scales (black arrows), and the flagella are covered in limulus scales (white arrows). these scale types are typical of motile quadriflagellate p. gelidicola cells (mcfadden et al. 1982). (g) sem of an eight-lobed morphotype. the mass shown here has no body or flagella scales, which were perhaps lost during the fixation process for this individual. the example has multiple flagella per lobe, and an isthmus separating the two four-lobed cell masses. (h) nomarski lm of a cyst cell, showing the thick cell wall (arrow), two starch grains (s) and numerous lipid (l) droplets. (i) sem of a cyst showing the cyst scale type that differs from scales found on the quadriflagellate. this cell was observed in freshly collected and preserved ace lake water. � table 1 comparisons of morphotypes reported (+) or not yet reported (–) in the literature for selected pyramimonas (prasinophyceae) species. antarctic species are set in bold; rs, ross sea; ws, weddell sea. pyramimonas species small and large cell types multilobed stage uniflagellate cell type cyst stage reference p. gelidicola + + + + this study p. tychotreta ws daugbjerg 2000 p. tychotreta rs + + daugbjerg et al. 2000 p. australis + moro et al. 2002 p. amylifera + + hargraves & gardiner 1980 p. parkeae + + + aken & pienaar 1981 p. pseudoparkeae + + pienaar & aken 1985 pleomorphism in pyramimonas gelidicolaj. van den hoff & j.m. ferris polar research 28 2009 426–432 © 2009 the authors 429 wall structure, a single nucleus and a diffuse mass of dna. perhaps the region of diffuse dna in this cell resulted from the dissolution of other nuclei during cyst formation. alternatively, the diffuse nuclear material seen resulted from cell damage during fixation. given that we lack observations on germinating cysts, we propose that in p. gelidicola, the process is likely to be similar to that in p. tychotreta (daugbjerg et al. 2000), in which the contents of cysts ultimately divided into four quadriflagellate cells that were released through a rupture in the cyst wall. the antarctic environment is extreme and highly changeable, and an encystment stage is one mechanism by which the pyramimonas species can tolerate such changes and survive the extremes of the antarctic environment. a variety of morphotypes observed here for p. gelidicola have been reported previously for p. amylifera (hargraves & gardiner 1980), p. parkeae (aken & pienaar 1981), pyramimonas pseudoparkeae (pienaar & aken 1985), p. tychotreta (daugbjerg et al. 2000) and p. australis (moro et al. 2002) (table 1). the p. gelidicola cultures contained two statistically different-sized single cell types (fig. 1a). two different-sized vegetative cell types have been observed in p. parkeae (aken & pienaar 1981) and p. pseudoparkeae (pienaar & aken 1985). the motile multilobed stages (fig. 1f, g), with up to eight lobes, of p. gelidicola were similar in appearance to those of p. amylifera (hargraves & gardiner 1980: fig. 14) and, to a lesser extent, to stage 7 of p. parkeae (aken & pienaar 1981: fig. 1). with the use of a dna stain (dapi), we report here that these are multinucleate stages, in most cases with an equal number of nuclei and lobes. as with hargraves & gardiner’s observations in 1980, we cannot comment on whether autogamy takes place at any time within the cell mass. multilobed stages of pyramimonas have yet to be observed in nature, or in the two other antarctic pyramimonas species (table 1). hargraves & gardiner (1980) described how differing environmental conditions produced varying numbers of p. amylifera multilobed stages in their cultures: the numbers were inversely correlated with temperature. for the present study, the temperature and light intensity were held constant, and thus the effects of manipulating these parameters were not investigated. however, the presence of various different morphological stages in the cultures suggests factors other than light and temperature are involved in their production. experimental manipulations would provide valuable information on how the life stages for p. gelidicola may change under growth conditions that model possible climatic change scenarios. from our limited observational record, binary fission in p. gelidicola (fig. 1b, c) was most similar to that described for p. australis (moro et al. 2002), p. parkeae (aken & pienaar 1981) and, to a lesser degree, with p. amylifera (hargraves & gardiner 1980) and pyramimonas quadrifolia (daugbjerg & moestrup 1993). like p. parkeae, cells of p. gelidicola can remain joined at the posterior (fig. 1c) for an undetermined period. a further incomplete division of such a cell at this time could result in the formation of a multilobed stage (fig. 1f). as with p. amylifera, such stages of p. gelidicola could be the product of incomplete cell division caused by a lack, or oversupply, of a culture medium component(s) critical to cytokinesis (hargraves & gardiner 1980). deeply invaginated forms are possibly at a more advanced period in their cell division processes than the more spherical forms. the budding of single lobes from a multilobed stage may be one mechanism by which the quadriflagellate is regenerated; this process has been observed for p. amylifera (hargraves & gardiner 1980) and p. parkeae (aken & pienaar 1981). the budding of single cells most likely occurs when the cell mass is at a deeply invaginated stage (i.e., where the cells are barely joined at the posterior). multilobed stages with an odd number of lobes were observed in our cultures, suggesting that a single cell had broken free through vegetative budding from the main cell mass. aggregations of, usually four, very vigorously swimming quadriflagellate cells were seen in cultures. these masses were distinguishable from the multilobed forms because, although closely associated with each other, each cell remained separate from other cells within the mass (fig. 1e). to our knowledge, no pyramimonas species are previously known to produce such a life form. whether these cells were aggregating, disaggregating or the product of excystment remains unresolved. we also observed, with lms only, a uniflagellate form of the vegetative cell type (fig. 1d). daugbjerg et al. (2000) saw such a form in p. tychotreta samples freshly collected from the wild, and, based on ultrastructural observations and scale morphology, they linked the uniflagellate to p. tychotreta, rather than reporting it as a new species. uniflagellate cells differed morphologically between the two species: in p. gelidicola, the cell shape was more like the quadriflagellate, whereas in p. tychotreta it was a rather more elongate cigar shape, compared with the quadriflagellate. daugbjerg et al. (2000) suggested that these cell types may represent a gamete, implying the occurrence of sexual reproduction in the life cycle of p. tychotreta. we cannot comment on the occurrence or otherwise of sexual reproduction in p. gelidicola, except to say that the presence of an unusual uniflagellate form in both p. tychotreta and p. gelidicola suggests that an alternative to asexual reproduction of the quadriflagellate is possible. pleomorphism in pyramimonas gelidicola j. van den hoff & j.m. ferris polar research 28 2009 426–432 © 2009 the authors430 overall, we lack real-time video footage of cells as they progressed through the various morphological stages, and thus the life cycle for p. gelidicola that we present in fig. 2 is purely conceptual. the model conceived draws on limited observations for p. gelidicola, combined with those from other pyramimonas species (hargraves & gardiner 1980; aken & pienaar 1981; daugbjerg et al. 2000). until proven otherwise, note that this model is only representative of the species growing under culture conditions. the model suggests three alternative cellular processes by which vegetative cells could reproduce. firstly, duplicating the population through binary fission of the singlecelled quadriflagellate (loop 1 in fig. 2). secondly, via the processes of encystment of the single cell and the subsequent excystment of a number of single cells (loop 2 in fig. 2). thirdly, cell multiplication could proceed via budding in the multilobed stage (loop 3 in fig. 2). our observations do not allow us to make any comment on the possibility that dna recombination takes place in multilobed stages, and, like daugbjerg et al. (2000), we found it difficult to place the uniflagellate form of p. gelidicola into a proposed life history, and so we make no attempt to do so. the significance of the cell aggregations is also unresolved. although it is unfortunate the original culture material that we isolated from ace lake is no longer available, and fig. 2 proposed life cycle for pyramimonas gelidicola in culture. the three alternative routes by which the quadriflagellate cell can reproduce are shown as loops 1, 2 and 3. from our current understanding, the uniflagellate cell type and cell aggregations cannot be placed in the life cycle. scale bar: 20 mm. the solid lines are the reported process for p. gelidicola. the dashed line is the speculative process for p. gelidicola, but is known for other pyramimonas species. pleomorphism in pyramimonas gelidicolaj. van den hoff & j.m. ferris polar research 28 2009 426–432 © 2009 the authors 431 that the work has not been followed up more recently, we feel it would be fruitful for others to investigate the causes of these aberrant cells in culture. acknowledgements andrew davidson, fiona scott and øjvind moestrup made constructive comments on early drafts of the paper. deborah riewesthal produced the life-cycle figure. as a result of the journal referees’ comments, this is a muchimproved paper. references aken m.e. & pienaar r.n. 1981. observations on the reproduction of pyramimonas parkeae norris et pearson (prasinophyceae). south african journal of science 77, 330–331. belcher j.h. 1969. further investigations on the type species of pyramimonas (p. tetrarhynchus schmarda) (prasinophyceae): an examination by light microscopy, together with notes on its taxonomy. botanical journal of the linnaean society 62, 241–253. bell e.m. & laybourn-parry j. 2003. mixotrophy in the antarctic phytoflagellate, pyramimonas gelidicola (chlorophyta: prasinophyceae). journal of phycology 39, 644–649. burch m.d. 1988. annual cycle of phytoplankton in ace lake, an ice covered, saline meromictic lake. hydrobiologia 165, 59–75. coleman a.w. 1985. cyanophyte and cyanelle dna: a search for organelles in plastids. journal of phycology 21, 371–379. daugbjerg n. 2000. pyramimonas tychotreta, sp. nov. (prasinophyceae), a new marine species from antarctica: light and electron microscopy of the motile stage and notes on growth rates. journal of phycology 36, 160–171. daugbjerg n., marchant h.j. & thomsen h.a. 2000. life history stages of pyramimonas tychotreta, sp. nov. (prasinophyceae, chlorophyta), a marine flagellate from the ross sea, antarctica. phycological research 48, 199–209. daugbjerg n. & moestrup ø. 1993. four new species of pyramimonas (prasinophyceae) from arctic canada including a light and electron microscope description of pyramimonas quadrifolia sp. nov. european journal of phycology 28, 3–16. hargraves p.e. & gardiner w.e. 1980. the life history of pyramimonas amylifera conrad (prasinophyceae). journal of plankton research 2, 99–108. laybourn-parry j., quayle w. & henshaw t. 2002. the biology and evolution of antarctic saline lakes in relation to salinity and trophy. polar biology 25, 542–552. mcfadden g.i., moestrup ø. & wetherbee r. 1982. pyramimonas gelidicola sp. nov. (prasinophyceae), a new species isolated from antarctic sea ice. phycologia 21, 103–111. moro i., la rocca n., dalla valle l., moschin e., negrisolo e. & andreoli c. 2002. pyramimonas australis sp. nov. (prasinophyceae, chlorophyta) from antarctica: fine structure and molecular phylogeny. european journal of phycology 37, 103–114. pienaar r.n. & aken m.e. 1985. the ultrastructure of pyramimonas pseudoparkeae sp. nov. (prasinophyceae) from south africa. journal of phycology 21, 428–447. van den hoff j., burton h.r. & vesk m. 1989. an encystment stage, bearing a new scale type, of the prasinophyte pyramimonas gelidicola and its paleolimnological and taxonomic significance. journal of phycology 25, 446–454. pleomorphism in pyramimonas gelidicola j. van den hoff & j.m. ferris polar research 28 2009 426–432 © 2009 the authors432 egg laying, chick growth and food of kittiwakes rissa tridactyla at hopen, svalbard robert t. barrelt barrett, r.t. 1996: egg laying, chick growth and food of kittiwakes rissa hidactyla at hopen, svalbard. polar research 15(2), 107-113. in 1984, kittiwakes at hopen laid eggs ca. 14 days later than previously found in north norway and on the kola peninsula. the mean clutch size, egg volume, and hatching success were otherwise very similar to those documented on the mainland. although feeding trips were very long, a rapid chick growth and high rate of chick survival suggested that food availability was not a limiting factor in 1984. in contrast to other sites at svalbard where polar cod boreogadrcs saida and crustaceans dominate kittiwake diets, the diets of chicks at hopen consisted mainly of capelin mallotus villosus which the adults probably collected at or beyond the polar front southeast of the island. robert t. barrett, zoology department, tromsm museum, university of tram@, n-9037 trams@, norway. introduction methods the kittiwake rissa tridactyla is extremely common throughout the barents sea region and breeds in large and small colonies on svalbard, franz josef land, novaja zemlja, the north coast of the kola peninsula and and in northern norway. of the ca. 900,000 pairs which breed in the region, ca. 270,000 nest on svalbard (includ ing bj~rnbya) (mehlum & bakken 1994; barrett & tertiski in press). while the breeding biology of the species has been studied in considerable detail along the coast of north norway and the kola peninsula (summarised in barrett & tertiski in press), most effort in the large colonies in the northern part of the barents sea has been put into studies of the energetics of the species (sum marked in gabrielsen 1994). apart from the presentation in gabrielsen et al. (1992) of a chick growth curve at a colony in kongsfjord, spitsber gen (79" n, 12" e), i have been unable to find other data concerning the breeding biology of kittiwakes from this region. this paper presents data from hopen (76" 35'n, 25" 20'e, fig. l), ca. 200 km east of s~rkapp, spitsbergen, where ca. 40,000 pairs of kittiwakes bred in 1984-1985 on several cliffs around the entire island (barrett & mehlum 1989). these data supplement gaston's (1988) documentation of kittiwake breeding biology in the northernmost part of the kittiwake's arctic range in the north atlantic. the data are also compared to similar data collected at colonies in north norway and northeast england. the study was carried out during the period 20 june-9 august 1984 in a small colony (2600-2800 nests, pers. obs.) ca. 500 m south of the meteorological station on the southeast coast of the island. sixty-four nests were individually marked and checked on alternate days beginning on 22 june. eggs were taken from 16 of these nests (for eating) by the station staff on 14 june. eggs, and later chicks, in each nest were fig. 1 . barents sea, showing the position of the localities mentioned in the text, the approximate positions of the polar front in july (from loeng 1989) and the main distribution of the adult capelin summer feeding grounds (shaded area, from dragesund 8-i gj0szter 1988). 108 r. t. barrett 14 12 $j 10 i? $ 4 g 8 3 6 2 0 3-4 7-8 11-12 15-16 19-20 individually marked and counted at each visit. laying dates were back calculated from hatching dates using a mean incubation period of 27d previously documented in the region (runde & barrett 1981). egg dimensions (length l and breadth b) were measured to the nearest 0.1 mm using vernier calipers, and egg volumes (v) were calculated using the formula v = lb x 0.4861 (runde & barrett 1981). chicks were weighed using pesola spring balances (25 g) and their wing lengths (max. flattened chord) were measured to the nearest 5 mm on each nest visit. logistic growth curves were fitted using ricklefs’ (1967) graphical method. eighty adults were also weighed (k5 g) during the incubation period, whereas the wing lengths of 112 adults were measured ( 2 1 mm) throughout the season, any food samples regur gitated by adults or chicks during handling were collected and frozen for later sorting in the laboratory. each food sample was weighed to fig. 2. the distribution of the laying dates of kittiwake eggs laid in 48 control nests, and 16 nests which were harvested on 14 june, at hopen in 1984. the nearest 1 g and the contents identified to the lowest possible taxa by examining otoliths and other recognisable hard parts using breiby (198s), harkonen (1986) and tromsa museum’s refer ence collection. the contribution of each prey taxa to the overall diet was expressed as the proportion by mass of the total mass of the samples. capelin lengths (snout to end of tail) were calculated using the equation fish length= otolith length x 48.0 + 25.8 (barrett unpubl.). all means are given 2 one standard deviation. results the mean laying date of 73 eggs of known laying or hatching date in the 48 control nests was 14 june 2 7 d (range 3-30 june, fig. 2). after the 14 june harvest, sixteen eggs were laid in 10 of the 16 harvested nests. three eggs in two of the clutches were laid only 5-6 days after the harvest. table 1. logistic growth parameters (based on ricklefs 1967, k = growth constant, w 4 = maximum instantaneous growth rate) of kittiwake chicks on hopen compared to colonies in north norway and england. hekkingen and north england data from barrett & runde (1980), bleikseya and horneya from barrett (1983, 1996). growth rate asymptote adult mass colony year a (9) w (g) r = a j w k ka/4(g/d) t i w d d ) hopen homeya horneya bleikwya hekkingen hekkingen hekkingen n. england n. england 1984 1980 1981 1986 1973 1974 1976 1954-57 1961-62 401 418 422 396 414 405 410 350 375 419 43 1 43 1 392 375 375 375 354 330 0.96 0.97 0.98 1.01 1.10 1.08 1.09 0.99 1.07 0.18 0.20 0.18 0.20 0.18 0.20 0.21 0.21 0.20 18.0 20.9 19.0 19.8 18.7 20.1 21.7 18.7 18.4 23.9 22.4 24.4 21.9 24.2 22.1 20.7 20.6 22.4 egg laying, chkk growth and food of kittiwakes rissa tridactyla at hopen, svalbard 109 fig. 3. the growth (mean body mass and wing length in relation to age) of kittiwake chicks at hopen in 1984. sample sizes are given above the x-axis and vertical lines indicate standard deviations. 300 d7 57 57 52 52 52 51 44 36 37 29 23 20 19 19 12 1-2 9-1 0 19-20 29-30 9 8 i i i i 1 i i , , i 1 ' 1 1 1 i i i i because replacement eggs are not usually laid until at least a week after the loss of the first clutch (maunder & threlfall 1972; barrett 1978, 1989), these three were considered as eggs of a first clutch, leaving 13 true replacement eggs. the laying dates of two eggs in one of the harvested nests is unknown because they were laid before we started the nest controls and lost before hatching. eleven of the remaining eggs were laid 13.5 f 2.3 days after the harvest (range 9-15 days). the mean clutch size in the 48 control nests was 1 . 7 ? 0.6 eggs (2 x 0, 11 x 1 and 35 x 2 eggs). no three-egg clutches were found. the mean volume of control eggs which could be reached was 45.5 t 3.4 ml ( n = 79) and of replacement eggs was 44.7 2 5.4 ml (n = 13). the difference was not significant (t = 0.54, p = 0.60). sixty-eight (89%) of 74 eggs in 45 of the control nests hatched. three eggs were lost, three did not hatch and two were abandoned. eight (62%) of 13 true replacement eggs in the harvested nests hatched. four eggs were lost in a rock fall and the fifth failed to hatch. the overall hatching success was 85.8% (79/92 eggs). two sample t-tests of the mean masses of chicks in 1-chick and 2-chick broods of the same age shoved brood size did not affect chick growth. similarly, chicks hatched early (before 7 july, n = 2 1 ) grew at the same rate as those hatched late (after 11 july, n = 2 7 ) such that growth data for all chicks were pooled. the overall growth curve of chicks was sigmoidal, logistic in form and reached an asymptote of 401 g (96% of mean adult mass which was age d 250 e 200 t, 150 e cn p 100 3 50 0 418.7 t 28.1, n = 80 during the incubation period, table 1) approximately 30 days after hatching (fig. 3). the maximum instaneous growth rate was 18.0 g/d. two chicks reached a maximum mass of 470 g. wing length increased steadily to ca. 240 mm at day 35/36 (fig. 3). this was equivalent to 78% of the mean adult wing length ( = 321.6 2 6.9 mm, n = 112). fifty three (69%) of the 77 chicks which hatched had either fledged or were still in the nest on the last day of the study (8 august). of the 24 which died, 12 (50%) were lost within the first week post-hatch, and a further five during the second week. of the 54 regurgitations collected, 38 were from chicks and 16 were from adults. eighty seven percent contained capelin mallotus villosus, 22% contained the hyperiid amphipod parathe misto libellula and 17% contained arctic cod boreogadus saida. other food items included the table 2. frequency of occurrence and proportion (by mass) of the food items in 54 kittiwake regurgitations at hopen, svalbard, july 1984. prey species/group mallotus villosus boreogadus saida leptagonus decagonus unidentified fish parathemisto libeilula pandalus sp. nereis sp. ~ ~ frequency of proportion by occurrence mass number % mass (g) %i 47 87 811 86 9 17 75 8 1 2 8 1 3 6 5 0.5 12 22 37 4 3 1 7 0.5 2 1 4 0.4 110 r. t. barrett prawn pandalus sp., polychaetes nereis sp., the fish leptagonus decagonus and unidentified fish. capelin also dominated the samples gravimetri cally, making up 86 % by mass of the samples collected (table 2). the mean masses of 31 chick and 14 adult regurgitations were 16.5 2 7.6 g and 29.6 f 17.5 g respectively. the difference was significant (t = 2.7, p = 0.02). using galbraith’s (1983) find ings that kittiwake chick regurgitations weigh 80% of the original feed mass, single chicks were fed ca. 30 g food and chicks and siblings in a two chick brood each received ca. 20 g. the mean length of 56 capelin found in the samples was 130.4 2 15.9 mm (range 95-162 mm). discussion the laying dates of kittiwakes on hopen in 1984 were similar to those recorded on novaja zemlja in the late 1940s, but, as to be expected in high arctic colonies, they were later (by ca. 14 days) than previously found on the ice-free coasts of norway and kola (belopol’skii 1957; barrett 1978, 1983). based on early studies summarised by lqvenskiold (1964) but in which data were not systematically collected, they were probably also later than found at b j ~ m ~ y a . they were, however, 10-14 days earlier than those found by gaston (1988) in the canadian high arctic and by fadley et al. (1989) at cape thompson in northern alaska. despite the fact that no three-egg clutches were found, the mean clutch size of hopen kittiwakes in 1984 was in the upper range of those found on hornsya, east finnmark (0.8-1.9 eggshest in 13 years between 1980-1995, pers. unpubl. data), where, in some years, up to 20% of the nests contained three eggs. uspenskii (1956) and swartz (1966) found three-egg clutches in only 1% of clutches studied on novaja zemlja and cape thompson respectively, and gaston found no three-chick broods in the canadian arctic in 1982. furthermore, a three-egg clutch was recorded only once in five studies carried out at b j ~ m ~ r a , kongsfjord and homsund at the turn of the century (bvenskiold 1964). although us penskii and swartz’ sample sizes were small, and gaston’s observations were from late in the season after a certain amount of egg and chick loss, these studies suggest that the normal clutch size of kittiwakes in the northermost part of the table 3. breeding success of kittiwakes at hopen in 1984 compared to other north norwegian colonies. hekkingen data from barrett (1978), bleiksdya data from barrett (1989) (= no data). ~ hekkingen hopen bleiksdya 1984 1973 1974 1975 1976 1986 no. eggs laid 92 286 91 246 100 % hatched 86 56 4 57 79 no. chicks hatched 77 81 146 118 79 % fledged 59’ 52 77 25 76 *assuming a further 10% loss between the last date of the study and final fledging species’ breeding range is one or two eggs and that the frequency of three-egg clutches is negligible. further south, in north sea colonies, the frequency of three-egg clutches has been recorded to be in the range 7-13% (cullen 1957; coulson & white 1958; poluszynski 1979). the interval between egg loss and replacement and the lack of difference in the egg volumes of first and replacement clutches were also similar to those found in two north norwegian studies (barrett 1978, 1989). this and the large clutch size suggest that factors determining kittiwake clutch initiation and egg volume around hopen were no more limiting than those found in the mainland colonies. similarly, the hatching success, chick growth, rate of chick loss and fledging success of kittiwakes on hopen were similar to those found in north norwegian colonies (tables 1 and 3), again suggesting that resources in the northern barents sea did not limit production in 1984. this is in contrast to other arctic colonies, e.g. colonies in alaska which have suffered from poor productivity since the mid-1970s due to low prey availability (hatch et al. 1993). there was no evidence of hopen chicks reaching a higher asymptotic mass than chicks in more southerly colonies (table 1) as was suggested for arctic breeding kittiwakes by gaston (1988). whereas capelin was an important constituent (up to 93%) of the diet of kittiwake chicks in several colonies in the southern barents sea (belopol’skii 1957; barrett & krasnov 1996), only once has it been documented in the northern part of the region as a very minor supplement to the diets of adults collected east of spitsbergen in spring and summer (lqnne & gabrielsen 1992; egg laying, chick growth and food of kittiwakes rissa tridactyla at hopen, svalbard 111 mehlum & gabrielsen 1993). capelin was not noted in the stomachs of springor autumn feeding kittiwakes in hornsund, nor amongst the summer diets of kittiwakes collected in kongs fjord, spitsbergen or at franz josef land (lyder sen et al. 1989; mehlum & gabrielsen 1993; weslawski et al. 1994). nor was capelin noted in the diet of auks and fulmars fulmarus glacialis in any of the above studies. in these studies and in nine historical studies of birds collected at svalbard during the breeding season (summarised by bvenskiold 1964), arctic cod and crustaceans dominated all the samples. the dominance of capelin in the chick diet at hopen is thus an interesting supplement to the overall picture of svalbard kittiwake diets. however, this is doubt less due to hopen being so far southeast of the main archipelago and very often on the western edge of the main summer feeding grounds of capelin (fig. 1). the size distribution and mean length of the capelin caught by kittiwakes at hopen were very similar to those collected at hornaya in the 1980s (barrett & furness 1990), but larger than those in their diet in southeastern alaska (median 81-90 mm in 1977, 51-70 mm in 1978, baird 1990). capelin of similar size (14-15 cm) were recorded during a fish survey 25-30 miles east of hopen in 1969 and 1970 (zaferman 1972). although capelin often occur near hopen during the summer, there are suggestions that in 1984 kittiwakes had to forage further than normal to obtain this capelin. a study of the energetics of kittiwakes in the same colony and season documented adult feeding trips lasting 17-29 hours (mean = 23 hours, n = 17, gabrielsen et al. 1987). fourteen of these adults had single chicks and three had two chicks. all chicks were 5-10 days old. however, gabrielsen et al’s (1987) observations of birds were made four times a day only and may thus have missed some feeding bouts. the resulting trip durations were much longer than previously recorded in, e.g., north norway. at hekkingen, kittiwakes fed their chicks 4-6 times a day (barrett 1978), whereas at hornaya the median feeding trip durations in 1983 were a little over one hour, indicating a foraging range of 27 km (furness & barrett 1985). trip durations recorded at hopen by gabrielsen et al. (1987) were also much longer than those recorded at other colonies where feeding condi tions were both good (2-4 hours, pearson 1968; watanuki et al. 1992; wanless & harris 1992; roberts & hatch 1993; hamer et al. 1993) and bad (10-14 hours, wanless & harris 1992; hamer et al. 1993). this suggests that hopen kittiwakes were either foraging much further afield than is normal for the species, possibly in the order of hundreds of kilometres, or that some of the feeding bouts were missed. as suggested by gabrielsen et al. (1987), it is also possible that some of the time away from the nest was spent resting, not foraging, thus further reducing the apparent foraging time and range. adults colour-dyed in 1984 at hopen were observed by passing ships ca. 40 km south-east of the island (pers. unpubl. data); this suggests that adults ranged far to the south or east of the island, possibly in or beyond the frontal zone between the atlantic and arctic currents (the polar front, fig. 1) in their search for food. this open-sea site is well beyond the areas covered by the previous studies of kittiwake diet at spitsbergen in which adult birds were collected in coastal or ice-filled waters. the distant foraging also suggests that 1984 was a year when the main summer distribution of capelin was far east of hopen. according to galkin & ushakov (1977), this is not an uncommon phenomenon. by september, however, capelin had spread northwestwards and were abundant very close to the island (h. gj~saeter, pers. comm.) although the adults may have been foraging very far afield to collect chick food, the mean masses of the adult and chick regurgitates were in the upper part of the ranges of those recorded on three north norwegian colonies in ten seasons (chicks 6-27 g, adults 9-36 g, barrett, unpubl. data) and during one season in scotland by galbraith (1983). the two heaviest adult regur gitates at hopen were 72 and 58 g, very similar to galbraith’s 68 and 53 g. maxima of 50-70 g were also recorded in the above-mentioned studies in north norwegian colonies. the hopen and galbraith’s maxima are ca. 18% of the respective adult body masses, suggesting that this is close to the maximum carrying capacity of kittiwakes when feeding their chicks. kittiwake chicks have a daily food requirement of ca. 80-100 g capelin when 10 days old (gabrielsen et al. 1992). if adults carry their food at their maximum capacity, this requirement could easily have been reached at hopen by adults even when feeding their chicks at the observed rate of a little more than once a day. however, with two chicks in the nest, adults would need to provide 112 r . t. barreat two to three times the maximum and thus increase their feeding frequency accordingly. unfortu nately, no feeding frequency data were collected for a large sample of two-chick nests. the high growth rates and fledging success, and the lack of differentiation in growth rates in relation to brood size suggest, however, that adults did indeed increase the feeding rate above that recorded by gabrielsen et al. (1987). acknowledgements. this study was financed by the norwegian research council for science and the humanities over the promare research programme, and by the university of troms0. special thanks are due to 1. johnsen, g.w. gabrielsen and f. mehlum for their help in the field, and to h. gjesaeter for locating maps of capelin distribution from the norwegian marine research institute’s multitude of cruise reports. 1 am also grateful to the meteorological office in north norway for permission to stay on their station at hopen and to the station’s staff for their help and hospitality. t. anker nilssen kindly made constructive comments to an early draft of the manuscript. references baird, p. h. 1990: influence of abiotic factors and prey distribution on diet and reproductive success of three seabird species in alaska. ornis scand. 21, 224-235. barrett, r. t. 1978: the breeding biology of the kittiwake, rissa tridactyla (l.), in troms, north norway. cand. real. thesis, univ. of t r o m s ~ . 132 pp + appendices. barrett, r. t. 1983: seabird research on horn@y, east finnmark with notes from nordland, troms and w. finn mark 1980-1983. a preliminary report. unpubl. rep., tromse museum, univ. of tromse. 62 pp. barrett, r. t. 1989 the effect of egg harvesting on the growth of chicks and breeding success of the shag phalacrocorax aristotelis and the kittiwake rissa tridactyla on bleiksey, north norway. ornis fennica 66, 117-122. barrett, r. t. 1996: prey harvest, chick growth and production of three seabird species on bleiksey, north norway during years of variable food availability. pp. 20-26 in montevec chi, w. a. (ed.): studies of high-latitude seabirds. 4. trophic relationships and energetics of endotherms in cold ocean systems. c w s occ. paper 91. ottawa. barrett, r. t. & furness, r. w. 1990. the prey and diving depths of seabirds on homey, north norway, after a decrease in the barents sea capelin stocks. ornis scand. barrett, r. t. & krasnov, y. v. 1996: recent responses to changes in stocks of prey species by seabirds breeding in the southern barents sea. ices j . mar. sci. 53, 713-722. barrett, r. t. & mehlum, f. 1989 bird observations and seabird census at hopen, svalbard. fauna now. ser. c, cinclus 12, 21-29. barrett, r. t. & runde, 0. j. 1980: growth and survival of nestling kittiwakes rissa tridactyla in norway. ornis scand. 11, 228-235. barrett, r. t. & tertiski, g. in press: the kittiwake rissa 21, 179-186. tridactyla. in ankef-nilssen, t., bakken, v., bianki, v., golovkin, a. & tatarinkova, i. (eds.): status of marine birds breeding in the barents sea region. belopol’skii, l. 0. 1957: ecology of sea colony birds of the barents sea. israel progr. for scientific translations, jerusalem. 346 pp. (translated from russian, 1961). breiby, a. 1985: otolitter fra saltavannsfisker i nordnorge. tromura natvitenskap nr. 45, univ. of tromse. 30 pp. coulson, j. c. &white, e. 1958: observations on the breeding of the kittiwake. bird study 5, 74-83. cullen, e. 1957 adaptations in the kittiwake to cliff-nesting. ibis 99, 275-302. dragesund, 0. & gjesaeter, j. 1988: the barents sea. pp. 339-361 in postma, h. & zijlstra, j. j. (eds.): continental shelves. ecosystems of the world 27. elsevier, amsterdam. fadley, b. s., piatt, j. f., hatch, s. a. & roseneau, d. g. 1989: populations, productivity, and feeding habits of seabirds at cape thompson, alaska. alaksa fish & wildl. res. center. final rep., ocs study mms 89-0014. us fish & wildl. serv. 429 pp. furness, r. w. & barrett, r. t. 1985: the food requirements and ecological relationships of a seabird community in north norway. ornis scand. 16, 305-313. gabrielsen, g. w. 1994: energy expenditure in arctic seabirds. dr. philos thesis, univ. of tromse. gabrielsen, g. w., klaasen, m. & mehlum, f. 1992 energetics of black-legged kittiwake rissa tridactyla chicks. ardea 80, 29-40. gabrielsen, g. w., mehlum, f. & nagy, k. a. 1987: daily energy expenditure and energy utilization of free-ranging black-legged kittiwakes. condor 8 9 , 126-132. galbraith, h. 1983: the diet and feeding ecology of breeding kittiwakes rissa tridactyla. bird study 30, 109-120. galkin, a. s. & ushakov, n. g. 1977: capelin investigations in the barents sea for 1971-1976. ices rep. c.m. 1977lh:6, 1-20. gaston, a. j. 1988: timing of breeding of kittiwakes rissa tridactyla and growth and diet of the chicks at hantzch island, n.w.t., canada. seabird 1 1 , 3-11. hamer, k. c., monaghan, p., uttley, j. d., walton, p. & bums, m. d. 1993: the influence of food supply on the breeding ecology of kittiwakes rissa tridactyla in shetland. ibis 135, 255-263. hatch, s. a., byrd, g. v., irons, d. b. & hunt, g. l. 1993: status and ecology of kittiwakes (rissa tridactyla and r. brevirostris) in the north pacific. pp. 140-153 in vermeer, k., b r i g s , k. t., morgan, k. h. & siegel-causey, d. (eds.): the status, ecology, and conservation of marine birds of the north pacific. cws special publ., ottawa. harkonen, t. 1986: guide to the otoliths of the bony fishes of the northeast atlantic. danbiu aps, hellerup. 256 pp. loeng, h. 1989: ecological features of the barents sea. pp. 327-365 in rey, l. proceedings of the 6th conference of the cornit6 artique international, 13-15 may 1985. e. j. brill. leiden. lydersen, c., gjertz, i. & weslawski, j. m. 1989: stomach contents of autumn-feeding vertebrates from homsund, svalbard. polar record 25, 107-114. lome, 0. j. & gabrielsen, g. w. 1992: summer diet of seabirds feeding in sea-ice-covered waters near svalbard. polar biol. 12, 685692. uvenskiold, h. l. 1964: avifauna svalbardensis. norsk polarinst. skr. no. 129, 1-455. egg laying, chick growth and food of kittiwakes rissa tridactyla at hopen, svalbard 113 maunder, j. e. & threlfall, w. 1972 the breeding biology of the black-legged kittiwake in newfoundland. auk 89, 789-816. mehlum, f. & bakken, v. 1994: seabirds in svalbard (norway): status, recent changes and management. pp. 155-171 in nettleship, d.n., burger, j. & gochfeld, m. (eds.): seabirds on islands. threats, case studies and action yfans. birdlife conservation series no. 1, cambridge, uk. mehlum, f. & gabrielsen, g.w. 1993: the diet of high-arctic seabirds in coastal and ice-covered, pelagic areas near the svalbard archipelago. polar res. 12, 1-20. pearson, t. h. 1968: the feeding biology of sea-bird species breeding on the fame islands, northumberland. j . animal poluszynski, j. 1979: some observations of breeding kittiwakes (rissa tridactyla) on helgoland. abh.a.d. geb. vogeld. 6 , 113-120. ricklefs, r. e. 1967 a graphical method of fitting equations to growth curves. ecol. 48, 978-983. roberts, b. d. & hatch, s. a. 1993: behavioral ecology of black-legged kittiwakes during chick rearing in a failing colony. condor 95, 330-342. e d . 37, 521-552. runde, 0. & barrett, r. t. 1981: variations in egg size and incubation period of the kittiwake rissa tridactyla in norway. o r n k scand. 12, 80-86. swartz, l. g. 1966: sea-cliff birds. pp. 6 1 1 4 7 8 in wilimovs ky, n. j. & wolfe, j. n. (eds.): environment of the cape thompson region, alaska. us atomic energy commission. uspenskii, s. m. 1956: the bird bazaars of novaya zemlya. cws translation of russian game reports, vol. 4, ottawa. 159 pp. (translated from russian, 1958). wanless, s. & harris, m. p. 1992: activity budgets, diet and breeding success of kittiwakes rissa tridactyla on the isle of may. bird study 39, 145-154. watanuki, y., naito, y. & schauer, j. 1992: chick diet and daily activity pattern of common murres and black-legged kittiwakes at bluff seabird colony, norton sound, alaska. proc. nipr symp. polar biol. 5 , 98-104. weslawski, j. m., stempniewicz, l. & galaktionov, k. 1994: summer diet of seabirds from the frans josef land archipelago, russian arctic. polar res. 13, 173-181. zaferman, m. l. 1972 observations on capelin in the area of hope island. materialy rybokhozyaistvennykh issledovanii severnogo basseina, 19, 93-100. (fish. res. bd., canada transl. ser. no. 2840, 1973). plant dispersal by canada geese in arctic greenland research note plant dispersal by canada geese in arctic greenland andy j. green a, ádám lovas-kiss b, rachel a. stroudc, niall tierneyc & anthony d. fox d adepartment of wetland ecology, estación biológica de doñana, csic, sevilla, spain; bdepartment of botany, faculty of sciences and technology, university of debrecen, debrecen, hungary; cfaculty of natural resources and environmental sciences, agricultural university of iceland, hvanneyri, iceland; ddepartment of bioscience, aarhus university, rønde, denmark abstract despite the abundance of migratory geese as herbivores in the arctic, and ongoing changes in their populations and distributions, little is known about their role in seed dispersal. climate change requires arctic plants to adjust their distributions, and avian vectors may have an important role to play. we present the first study of endozoochory (internal transport) of arctic plants by canada geese. in central west greenland, we collected 50 faecal samples, from which we extracted 2943 intact seeds from six species and four families, all but one of which (a non-native species) are extremely common and widespread in this part of greenland. the majority (95%) of seeds were from empetrum nigrum, but carex nardina (3%) and vaccinium uliginosum (2%) were also abundant. one seed of the non-native persicaria lapathifolia was recorded. these results suggest migratory geese are likely to be vital vectors of arctic plants. although the sample size was small, there were indications that nonbreeding geese may disperse more seeds than breeding geese, which stay closer to lakes to reduce the risk of predation, rarely accessing dwarf-scrub heath where non-breeders ingested seeds. future research should address such possible links between reproductive status and seed dispersal in waterbirds. keywords branta canadensis; carex; empetrum; endozoochory; faeces; seed dispersal arctic plant species assemblages are highly structured, on account of sequential pleistocene glaciations and long-established physical barriers to dispersal and gene flow (such as mountain chains, glaciers and the oceans (alsos et al. 2015; eidesen et al. 2013) as well as biotic interactions such as herbivory (post & pedersen 2008). vertebrate seed dispersers are important to maintain and enhance arctic plant community richness (bruun et al. 2008). this is especially significant in these times of climate change, which is reducing the extent of sea and terrestrial ice, and affecting seasonality, precipitation and wind patterns. changing climate and resultant short-term changes in the arctic environment (for instance, in land ice cover) create new opportunities for colonization of novel plant species and genotypes, as well as imposing different templates for patterns of activity, growth, reproduction and dispersal of existing plant life forms in these regions (klein et al. 2008). such vegetation dynamics are dependent on effective dispersal processes, including endozoochory (dispersal of seeds and other diaspores via gut passage) by migratory geese and other herbivores. although the role of arctic geese as herbivores and in nutrient cycling is well documented (e.g., ruess et al. 1989; jefferies et al. 1994), only a handful of studies worldwide show that geese can disperse a variety of plants both with and without a fleshy fruit (garcía-álvarez et al. 2015; green et al. 2016). as yet there is almost no information on the roles geese may play in maintaining and enhancing the diversity of arctic plant communities. here, we report on endozoochory by canada geese (branta canadensis interior) in a coastal area of central west greenland, and consider their likely role as vectors in the local changes in cover of native and nonnative plant species. although apparently present in west greenland since at least the 1860s, canada geese have recently increased in abundance and range in west greenland and have colonized this specific study area since the 1980s (malecki et al. 2000; fox & glahder 2010; fox et al. 2011; fox et al. 2012). study area, materials and methods the study area lies north and east of the town of ilulissat (69° 13ʹn 51°6ʹw) in central west greenland (fig. 1). the area comprises a rocky plateau 100–400 m a.s.l. covered by dwarf-scrub heath vegetation. dominant species are cassiope tetragona, empetrum nigrum and vaccinium uliginosum microphyllum, with some graminoids, and on the dry barrens dryas octapetala, salix arctica and graminoids such as carex nardina and kobresia myosuroides. wetter sites and lake margins are dominated by eriophorum scheuchzeri and carex rariflora. canada geese spending the summer in this contact anthony d. fox tfo@bios.au.dk department of bioscience, aarhus university, kalø, grenåvej 14, rønde dk-8410, denmark polar research 2018, vol. 37, 1508268 https://doi.org/10.1080/17518369.2018.1508268 © 2018 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0002-1268-4951 http://orcid.org/0000-0002-8811-1623 http://orcid.org/0000-0001-8083-7633 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2018.1508268&domain=pdf area in july/early august comprise either moulting flocks of non-breeding (i.e., failed breeders or subadult individuals) or family groups of parents with goslings (too small to fly). all geese tend to resort to the open water of lakes and streams when threatened by predators such as arctic fox (vulpes lagopus), the only mammalian predator of this region, so tend to be constrained to feed close to water, although they will forage away from shorelines on relatively profitable food. fifty samples of fresh canada goose droppings were collected from three sites near ilulissat from 12 to 19 july 2016 within one to two hours of observing the birds feeding there (fig. 1). thirty-two faecal samples were obtained from a flock of 28 non-breeders moulting flight feathers on a lake at 69°19ʹ08.0”n 50° 48ʹ41.6”w on 19 july 2016, seven from nine nonbreeding moulters at 69°15ʹ27.9”n 50°48ʹ05.6”w on 12 july 2016 and 11 from a family of two adults (five faecal pellets mean dry mass 3.74 g ± 0.82 s.e.) and four goslings (six faecal pellets mean dry mass 2.06 g ± 0.34 s.e., judged on clear size difference to adult faeces from young aged 25–30 days old and half grown) on 14 july 2016 at 69°14ʹ13.7”n 50°54ʹ34.0”w. droppings from the non-breeder flock were 12–15 mm in diameter, adult droppings in the family groups were distinguishable in this way from the gosling faeces, which were ca. 5–8 mm diameter. although the very slightly smaller greenland white-fronted goose (anser albifrons flavirostris) is endemic to west greenland, this species was not observed during protracted exploration of the study area. this, together with our detailed observations of the canada goose groups prior to faecal collection, gives us confidence that we sampled exclusively from this species. all samples were freshly collected and sun dried, placed in envelopes and transported in plastic bags to hungary for further investigation. in hungary, samples were kept refrigerated at 4°c until analysis. samples were then soaked in deionized water, sieved with a 100 µm sieve and deionized water, then inspected under a binocular microscope for plant diaspores. only intact, uncracked seeds were extracted and quantified. the seeds were identified based on shape, size, colour and seed coat pattern, in accordance with the recent literature (aiken et al. 2007; cappers et al. 2012; usda, nrcs 2018). viability tests were run for seeds on 1 august 2017, using the peroxidase test (copeland & mcdonald 1999). for those species for which we extracted more than 50 seeds, we randomly selected a subset of 50 (table 2). as a consequence of their smaller size, some of the v. uliginosum seeds were accidentally destroyed during the testing process, so that final sample size was 25 (table 2). seeds were soaked for 12 h in deionized water, cut in half and inspected to confirm the presence of an embryo. half of each seed was immersed in 10% h2o2 solution, drained off and the seeds were rinsed in 90% ethyl alcohol followed by ph 8 phosphate buffer. finally, the seeds were soaked in benzidine diluted in 80% ethyl alcohol, which immediately turns viable seeds to a distinctive dark colour. results from the 50 dried samples (mean dry mass = 3.536 g ± 2.39 g s.d.), we recovered a total of 2943 seeds, belonging to six species from four plant families (table 1). only one plant taxon was an aquatic emergent (hippuris vulgaris); the remainder were terrestrial species. one family (ericaceae) comprised two berry-bearing species; the others had no obvious adaptations for endozoochory. overall, of all the faecal samples, 39 (78%) contained at least one seed (table 1). we found one seed from the non-native persicaria lapathifolia in one sample from the non-breeding flock, a plant species occurring outside its natural range, introduced to greenland through human agency (böcher et al. 1978). faecal samples from non-breeding flocks were rich in seeds, and 95% of these samples contained at least one seed. in contrast, only 18% of samples from the goose family contained any seeds (table 1). the peroxidase test confirmed viability for seeds of c. nardina, e. nigrum, v. uliginosum and p. lapathifolia (table 2). we also recorded fragments of mosses or lichens in four of our samples, which potentially were viable at the time of egestion. discussion we showed that canada geese are potentially important seed vectors in the arctic biome, and that they disperse a range of flowering plant taxa by endozoochory. we focussed our study on large diaspores preserved after drying, but it is also possible that the canada geese were vectors for the spores or viable fragments of the mosses and lichens, which were additional components of their diet (wilkinson figure 1. study area in greenland in relation to the town of ilulissat. 2 a. j. green et al. et al. 2017; lovas-kiss et al. 2018). our conservative viability test, conducted a year after faeces were collected, confirmed viability of > 10% of seeds. our findings are consistent with previous studies suggestingthatthisgoosespecies isanimportantplantvector in other biomes. morton & hogg (1989) germinated seeds of three species from canada geese faeces collected on an island in georgian bay, great lakes, including v. angustifolium, which did not grow on the island and was thought to be dispersed several kilometres from the lake shore. neff & baldwin (2005) germinated six taxa from faeces in a freshwater marsh in washington d.c. best and arcese (2009) germinated five taxa from faeces from islands near vancouver. in the only previous study of endozoochory by arctic geese we are aware of, bruun et al. (2008) recorded viable seeds of 12 taxa (including c. nardina, k. myosuroides and v. uliginosum) in faeces of barnacle geese b. leucopsis in coastal north-east greenland. canada geese have recently increased in abundance in west greenland and can assist in the dispersal of native plant species that are shifting their distribution, as well as potentially with new additions to the greenland flora, especially under a scenario of rapid climate change (klein et al. 2008). they are also thought to be the vectors of local dispersal for daphnia that rapidly colonize new ponds and lakes formed as ice retreats in western greenland (haileselasie et al. 2016). the appearance of a single seed of p. lapathifolia suggests geese have a role in the spread of non-native species in greenland. this plant is also non-native in the canadian arctic (usda, nrcs 2018), and to date in west greenland it is relatively restricted to the vicinity of human settlements along the coast. geese and other waterbirds are known to disperse many non-native plants (green 2016), and p. lapathifolia has been recorded as dispersed by european dabbling ducks (green et al. 2016). on islands near vancouver, canada geese have been shown to play a key role in the spread of non-native grasses through both endozoochory and grazing (best & arcese 2009). larger seeds are thought more likely destroyed during passage through the avian gut, so it is noteworthy that all the seeds we recorded were > 1 mm and < 3 mm long (in contrast to studies of endozoochory by european ducks (soons et al. 2016; lovas-kiss et al. 2018). two of the three most abundant angiosperms in our samples have a fleshy fruit characteristic of an endozoochory syndrome (table 1). in contrast, half of the species we recorded are usually assumed to rely on gravity (barochory) or water (hydrochory) for their dispersal (table 1). although we sampled the geese at a time when they would probably deposit seeds only tens or hundreds of metres away from the mother plants, this is likely to be further than the seeds could disperse by other means such as water or wind (bullock et al. 2017). this may therefore represent a vital process enabling changes in vegetation in response to climate change (gonzalez-varo et al. 2017). furthermore, it is very possible that the geese can disperse these same plant species over hundreds of kilometres during their long-distance migrations in a similar manner to migratory ducks, since the longest seed retention times in the guts of geese exceed the time required for migration (viana et al. 2013; garcía-álvarez et al. 2015). geese have not been shown to empty their digestive tract before migrations, and flight activity is likely to increase seed survival (kleyheeg et al. 2015). a role for geese as long-distance vectors in arctic environments is strongly consistent with genetic and floristic analyses (alsos et al. 2015). all the plant species we recorded are widely distributed in canada and the coastal usa (usda, nrcs 2018), suggesting that canada geese may have contributed as vectors to their broad distributions and to contemporary long-distance gene flow. table 1. plant diaspores recovered from canada goose droppings in greenland. total number of intact seeds (ts), number of samples with seeds (ns) and maximum number of seeds in any given sample (max). plants non-breeding (n = 39) breeding (n = 11) family species length (mm)a dispersal syndromeb ts ns max ts ns max cyperaceae carex nardina 2.22 ndc 82 16 22 – – – kobresia myosuroides 2.63 barochory 8 6 3 – – – ericaceae empetrum nigrum 1.85 endozoochory 2780 32 494 2 1 2 vaccinium uliginosum 1.3 endozoochory 69 11 25 – – – plantaginaceae hippuris vulgaris 1.85 hydrochory – – – 1 1 1 polygonaceae persicaria lapathifoliad 2.88 barochory 1 1 1 – – – total 2940 37 494 3 2 2 alength data were derived from the leda database (kleyer et al. 2008) and our own measurements. bdispersal syndromes were taken from baseflor (julve 1998): barochory implies self-dispersal via gravity, hydrozoochory implies water dispersal, endozoochory implies dispersal via frugivory. cno data because this species is not listed in baseflor. wind dispersal has been proposed elsewhere for c. nardina (flora of svalbard 2018). dspecies not native to greenland according to böcher et al. (1978). table 2. viability of seeds recovered from canada goose droppings in greenland. results of the peroxidase test for a subset of seeds, showing numbers of tested seeds (ts), seeds with an embryo (se), and viable seeds (vs). family species ts se vs cyperaceae carex nardina 50 7 4 kobresia myosuroides 8 0 0 ericaceae empetrum nigrum 50 10 3 vaccinium uliginosum 25 12 6 plantaginaceae hippuris vulgaris 1 0 0 polygonaceae persicaria lapathifolia 1 1 1 total 135 30 14 polar research 3 in spite of the small sample size, our results also suggest that endozoochorous seed dispersal by arctic geese can be affected by microhabitat use, which could potentially be related to social status. different groups from within a given goose population that feed within the same landscape, but differ in social status, can show radically different diets. our results are consistent with our direct field observations of canada goose behaviour during the moult period. non-breeding canada geese tend to aggregate into relatively large flocks during the ca. three weeks they are flightless. during this time, they resort to the safety of open water bodies to avoid predation, largely from arctic fox, but may feed out on dwarfscrub heath where their diet may be predominantly the berries of e. nigrum and v. uliginosum, which frequently form the dominant vegetation cover in areas of deeper soil. empetrum berries provide relatively little metabolizable biomass for geese, but may provide critical antioxidants and fatty acids, which may be important for completion of moult and for successful autumn migration (e.g., hupp et al. 2013). the larger flock size of nonbreeders enhances predator detection, enabling them to forage at greater distances from the water’s edge than smaller groups of breeding pairs with their broods. breeding groups tend to graze the aboveground growth of graminoids such as c. rariflora along lake shores, especially when goslings are very young, rarely leaving the safety of peripheral lake wetland habitats to ensure an escape route to open water. hence, they do not tend to feed where the berries and dry habitat graminoids such as c. nardina occur. given that we only collected faeces from breeding birds at a single site, however, we remain prudent about inferring much from the differences between these and the more abundant samples from non-breeders at two sites. more detailed studies are required to fully investigate the role of arctic geese as plant vectors at different spatial scales. this should include the influence of social status on microhabitat use and the quantity and quality (sensu schupp et al. 2010) of seed dispersal, a research topic not yet addressed in waterbirds (green et al. 2016). acknowledgements this study was supported by spanish ministerio de economía, industria y competitividad project cgl2016-76067-p (aei/ feder, eu) to ajg. alk was supported by the new national excellence program únkp-17-3-i-de-385. we greatly appreciate the help of csaba máthé, márta mikóné hamvas and tamás garda in undertaking the viability tests. we thank juan p. gonzález-vero and two anonymous referees for comments and suggestions that improved the article. disclosure statement no potential conflict of interest was reported by the authors. funding this work was supported by the new national excellence program (únkp-17-3-i-de-385) and the spanish economy ministry (cgl2016-76067-p). orcid andy j. green http://orcid.org/0000-0002-1268-4951 ádám lovas-kiss http://orcid.org/0000-0002-8811-1623 anthony d. fox http://orcid.org/0000-0001-8083-7633 references aiken s.g., dallwitz m.j., consaul l.l., mcjannet c.l., boles r.l., argus g.w., gillett j.m., scott p.j., elven r., leblanc m.c., gillespie l.j., brysting a.k., solstad h. & harris j.g. 2007. flora of the canadian arctic archipelago: descriptions, illustrations, identification, and information retrieval. ottawa: nrc research press, national research council of canada. accessed on the internet at http://nature.ca/ aaflora/data on 3 june 2017. alsos i.g., ehrich d., eidesen p.b., solstad h., westergaard k. b., schönwetter p., tribsch a., birkeland s., elven r. & brochmann c. 2015. long-distance plant dispersal to north atlantic islands: colonization routes and founder effect. aob plants 7, plv036, doi: 10.1093/aobpla/plv036. best r.j. & arcese p. 2009. exotic herbivores directly facilitate the exotic grasses they graze: mechanisms for an unexpected positive feedback between invaders. oecologia 159, 139–150. böcher t.w., fredskild b., holmen k. & jakobsen k. 1978. grønlands flora. (greenland's flora.) copenhagen: p. haase & søns forlag. bruun h.h., lundgren r. & phillip m. 2008. enhancement of local species richness in tundra by seed dispersal through the guts of muskox and barnacle goose. oecologia 155, 101–110. bullock j.m., gonzalez l.m., tamme r., gotzenberger l., white s.m., partel m. & hooftman d.a.p. 2017. a synthesis of empirical plant dispersal kernels. journal of ecology 105, 6–19. cappers r.t.j., bekker r.m. & jans j.e.a. 2012. digitale zadenatlas van nederland. digital seed atlas of the netherlands. 2nd edn. groningen: barkhuis. copeland l.o. & mcdonald m.b. 1999. seed viability testing. in l.o. copeland & m.b. mcdonald (eds.) principles of seed science and technology. pp. 111–126. boston: springer. eidesen p.b., ehrich d., bakkestuen v., alsos i.g., gilg o., taberlet p. & brochman c. 2013. genetic roadmap of the arctic: plant dispersal highways, traffic barriers and capitals of diversity. new phytologist 200, 898–910. flora of svalbard 2018. the flora of svalbard. accessed on the internet at http://svalbardflora.no on 1 august 2018. fox a.d. & glahder c.m. 2010. distribution and abundance of post moulting white-fronted and canada geese in west greenland 2007. polar research 29, 413–420. fox a.d., mitchell c., weegman m.d., griffin l., thomas h., stroud d.a. & francis i.s. 2011. potential factors influencing increasing numbers of canada geese in isunngua, west greenland. wildfowl 61, 30–44. fox a.d., sinnett d., baroch j., stroud d.a., kampp k., egevang c. & boertmann d. 2012. the status of canada goose subspecies in greenland. dansk ornitologisk forenings tidsskrift 106, 87–92. 4 a. j. green et al. http://nature.ca/aaflora/data http://nature.ca/aaflora/data https://doi.org/10.1093/aobpla/plv036 http://svalbardflora.no/on garcía-álvarez a., van leeuwen c.h.a., luque c.j., hussner a., vélez-martín a., pérez-vázquez a., green a.j. & castellanos e.m. 2015. internal transport of alien and native plants by geese and ducks—an experimental study. freshwater biology 60, 1316–1329. gonzalez-varo j.p., lopez-bao j.v. & guitian j. 2017. seed dispersers help plants to escape global warming. oikos 126, 1600–1606. green a.j. 2016. the importance of waterbirds as an overlooked pathway of invasion for alien species. diversity and distributions 22, 239–247. green a.j., brochet a.l., kleyheeg e. & soons m.b. 2016. dispersal of plants by waterbirds. in c.h. şekercioğlu et al. (eds.): why birds matter: avian ecological function and ecosystem services. pp. 147–195. chicago: university of chicago press. haileselasie t.h., mergeay j., weider l.j., jeppesen e. & de meester l. 2016. colonization history and clonal richness of asexual daphnia in periglacial habitats of contrasting age in west greenland. journal of animal ecology 85, 1108–1117. hupp j.w., safine d.e. & nielson r.w. 2013. response of cackling geese (branta hutchinsii taverneri) to spatial and temporal variation in the production of crowberries on the alaska peninsula. polar biology 36, 1243–1255. jefferies r.l., klein d.r. & shaver g.r. 1994. vertebrate herbivores and northern plant communities: reciprocal influences and responses. oikos 71, 193–206. julve p. 1998. baseflor. index botanique, écologique et chorologique de la flore de france. (baseflor. botanical, ecological and chorological index of the flora of france.) lille: institut catholique de lille. accessed on the internet at http:// perso.wanadoo.fr/philippe.julve/catminat.htm on 15 june 2016. klein d.r., bruun h.h., lundgren r. & phillip m. 2008. climate change influences on species interrelationships and distributions in high-arctic greenland. advances in ecological research 40, 81–100. kleyer m., bekker r.m., knevel i.c., bakker j.p., thompson k., sonnenschein m., poschlod p., van groenendael j.m., klimeš l., klimešová j., klotz s., rusch g.m., hermy m., adriaens d., boedeltje g., bossuyt b., dannemann a., endels p., götzenberger l., hodgson j.g., jackel a.-k., kühn i., kunzmann d., ozinga w.a., römermann c., stadler m., schlegelmilch j., steendam h.j., tackenberg o., wilmann b., cornelissen j.h.c., eriksson o., garnier e. & peco b. 2008. the leda traitbase: a database of life-history traits of northwest european flora. journal of ecology 96, 1266–1274. kleyheeg e., van leeuwen c.h.a., morison m.a., nolet b.a. & soons m.b. 2015. bird-mediated seed dispersal: reduced digestive efficiency in active birds modulates the dispersal capacity of plant seeds. oikos 124, 899– 907. lovas-kiss á., vizi b., vincze o., molnár v.a. & green a. j. 2018. endozoochory of aquatic ferns and angiosperms by mallards in central europe. journal of ecology 106, 1714–1723. malecki r.a., fox a.d. & batt b.d.j. 2000. an aerial survey of nesting white-fronted and canada geese in west greenland. wildfowl 51, 49–58. morton j.k. & hogg e.h. 1989. biogeography of island floras in the great lakes. 2. plant dispersal. canadian journal of botany—revue canadienne de botanique 67, 1803–1820. neff k.p. & baldwin a.h. 2005. seed dispersal into wetlands: techniques and results for a restored tidal freshwater marsh. wetlands 25, 392–404. post e. & pedersen c. 2008. opposing plant community responses to warming with and without herbivores. proceedings of the national academy of sciences 105, 12353–12358. ruess r.w., hik d.s. & jefferies r.l. 1989. the role of lesser snow geese as nitrogen processors in a sub-arctic salt marsh. oecologia 79, 23–29. schupp e.w., jordano p. & gomez j.m. 2010. seed dispersal effectiveness revisited: a conceptual review. new phytologist 188, 333–353. soons m.b., brochet a., kleyheeg e., green a.j. & jongejans e. 2016. seed dispersal by dabbling ducks: an overlooked dispersal pathway for a broad spectrum of plant species. journal of ecology 104, 443–455. usda, nrcs 2018. plants database. national plant data team, natural resources conservation service, us department of agriculture, greensboro, nc 27401-4901 usa. accessed on the internet at http://plants.usda.gov on 1 august 2018. viana d.s., santamaria l., michot t.c. & figuerola j. 2013. allometric scaling of long-distance seed dispersal by migratory birds. american naturalist 181, 649– 662. wilkinson d.m., lovas-kiss á., callaghan d.a. & green a.j. 2017. endozoochory of large bryophyte fragments by waterbirds. cryptogamie bryologie 38, 223–228. polar research 5 http://perso.wanadoo.fr/philippe.julve/catminat.htm http://perso.wanadoo.fr/philippe.julve/catminat.htm http://plants.usda.gov abstract study area, materials and methods results discussion acknowledgements disclosure statement funding references ontogenetic changes in the feeding strategy of lepidonotothen nudifrons (pisces, nototheniidae) off the south shetland islands and the antarctic peninsula research article ontogenetic changes in the feeding strategy of lepidonotothen nudifrons (pisces, nototheniidae) off the south shetland islands and the antarctic peninsula gabriela blasina a,b, andrea lopez cazorlaa,b, mariana deli antonic,d, daniel brunoe, matías delpianic,d & juan martín díaz de astarloac,d alaboratorio de vertebrados, departamento de biología, bioquímica y farmacia, universidad nacional del sur (uns), bahía blanca, argentina; binstituto argentino de oceanografía, consejo nacional de investigaciones científicas y técnicas (conicet)/universidad nacional del su (uns), bahía blanca, argentina; cinstituto de investigaciones marinas y costeras, consejo nacional de investigaciones científicas y técnica (conicet)/universidad nacional de mar del plata (unmdp), mar del plata, argentina; dgrupo de biotaxonomía morfológica y molecular de peces, /universidad nacional de mar del plata (unmdp), mar del plata, argentina; elaboratorio de ecología, fisiología y evolución de organismos acuáticos, consejo nacional de investigaciones científicas y técnicas (conicet), ushuaia, argentina abstract the diet and feeding strategy of lepidonotothen nudifrons off the south shetland islands and the antarctic peninsula, as well as their variation in relation to ontogenetic stage (juvenile– adult) and sampling area, were determined by stomach contents analysis. additionally, the trophic level of this species was estimated to determine its position within the antarctic food web. out of 247 specimens with prey in their stomachs, 144 were caught near the south shetland islands and 103 off the antarctic peninsula. ontogenetic changes in the trophic ecology of l. nudifrons were observed in both areas and were mainly related to a decrease of copepods and an increase of euphausiids in the diet. the diet of juveniles from the south shetland islands was characterized by the dominance of calanoid copepods, followed by isopods and amphipods, whereas diet off the antarctic peninsula was dominated by amphipods and cyclopoid copepods. the diet in adults was dominated by amphipods and euphausiids in both areas. the specialization of individual predators on different prey types was observed when considering the whole population of l. nudifrons, but when ontogenetic stages were considered separately it showed a more mixed feeding strategy, with different dominant prey for each class. although the trophic level increased with fish size, l. nudifrons can be classified as secondary consumer throughout its lifespan. keywords antarctic fish diet; zonerelated changes; dominant prey; feeding strategy; trophic level; food web abbreviations anova: one-way analysis of variance test; ap: antarctic peninsula; np-manova: non-parametric permutation multivariate analysis of variance; ssi: south shetland islands; tr: trophic level introduction antarctic coastal fish communities are composed of species not found elsewhere in the world (knox 2006). these communities are isolated and are, structurally and functionally, the result of millions years of co-adaptation and co-evolution among fish species (eastman 2005). current climate change, coupled with the impacts related to human activities, threatens the equilibrium and stability of antarctic ecosystems. to evaluate the human activity effects on these ecosystems it is essential to know their structure and dynamic (heath et al. 2012). studying growth, reproduction and feeding habits of antarctic fishes is necessary to understand their biology and ecology, as well as their relationship with other components in the antarctic marine ecosystem (kock et al. 2012). coastal antarctic fish fauna is dominated by highly endemic species of the family nototheniidae. these species have demersal lifestyles as adults, but develop from pelagic larvae (eastman 2005). generally, nototheniids occupy intermediate food web positions in the southern ocean (kock et al. 2012) and have developed several feeding strategies to utilize different food resources in a variety of habitats (targett 1981; fanta & meyer 1998). they feed on both benthic and epibenthic invertebrates, and are preyed upon by other fishes, seals and birds (la mesa et al. 2004). to determine the role of nototheniids in the antarctic marine ecosystem is essential to understand the energy flow in its food web (barrera-oro 2003). lepidonotothen nudifrons (lönnberg 1905) inhabits antarctic waters between 3 and 400 m depths and is among the most abundant and broadly distributed demersal fish off the ssi and the ap (llompart et al. 2015). reaching a maximum size of 220 mm total length and attaining sexual maturity at four or five years of age, it is small and slow growing (hourigan & radtke 1989). this species is ecologically important on account of its ecological role as predator and prey (barrera-oro 2002; la mesa et al. 2004). the dietary composition of l. nudifrons has contact gabriela blasina gabriela_blasina@hotmail.com laboratorio de vertebrados, departamento de biología, bioquímica y farmacia, universidad nacional del sur, san juan 670, bahía blanca 8000, argentina polar research, 2017 vol. 36, 1331558 https://doi.org/10.1080/17518369.2017.1331558 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0001-8000-9846 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1331558&domain=pdf been previously reported from south georgia and the south orkney islands (targett 1981), the ssi (barrera-oro 2003) and the danco coast in the western ap (casaux et al. 2003). in all these investigations, l. nudifrons was found to feed mainly on copepods, amphipods, polychaetes and shrimps. the diet of antarctic fish is likely to vary considerably between years, especially in an environment in which one of the major prey items, such as krill, exhibit huge inter annual variability. furthermore, feeding habits and diet composition of fish species can change during its ontogeny, as well as its role in the ecosystem (moreira et al. 2014). however, comparative studies on feeding ecology of juvenile and adult stages, as well as regional pattern change, have not been carried out so far. the aims of this study were: (1) to provide new insights on the diet of l. nudifrons; (2) to compare the feeding habits and feeding strategy of juveniles and adults; and (3) to estimate their trophic level off the ssi and the ap, in order to determine both their position and ecological role within the antarctic food web. materials and methods a total of 269 specimens of l. nudifrons were collected off the ssi and the ap (fig. 1). of them, 156 were caught off the ssi, ranging between 63 and 178 mm total length (tl), and 113 off the ap, with a size range of 55–166 mm tl. fish were caught during the 2011 summer austral campaign of argentina’s national scientific and technical research council (table 1), on board the puerto deseado oceanographic vessel, by a demersal bottom trawl pilot net with 25 mm mesh size. fishing hauls were performed at a speed of 2–3 knots for 15 minutes and all the fish captured were identified following de witt et al. (1990), counted and frozen at −10°c. afterwards, individuals were measured to the nearest millimetre to determine tl and standard length (sl), weighted to the nearest 0.01 g (w) and their stomach contents were removed. specimens were classified in two size classes, according to the length at first maturity (hourigan & radtke 1989): juvenile (≤93 mm sl) and adult fishes (>93 mm sl). only specimens containing food in their stomachs were used for the diet analyses. of them, 144 (72 juveniles and 72 adults) were caught off the ssi, ranging between 63 and 175 mm tl, and 103 (55 juveniles and 48 adults) off the ap, with a size range of 55–166 mm tl (fig. 2). the vacuity index (iv) and the stomach repletion index (isr) were calculated for each sampling area. the iv was calculated as: (number of empty stomachs/total number of stomachs examined) × 100 (molinero & flos 1992). isr was calculated as: (wf/w) × 100, where w is the fish weight and wf is the ingested food weight (okach & dadzie 1988). a t-test was applied to analyse differences between isr from both the ssi and the ap. figure 1. sampling area, including the ssi and the ap. black dots represent the stations where fishing hauls were performed. table 1. details of the fishing hauls performed off the ssi and the ap. date latitude longitude water temp. (°c) salinity depth (m) juvenilea adulta 17 february 2011 62° 04.2′ s 57° 29.3′ w 2.3 33.9 203 16 13 17 february 2011 62° 09.7′ s 58° 03.4′ w 2.1 34.0 105 10 13 19 february 2011 62° 22.3′ s 58° 53.9′ w 2.1 33.8 123 16 16 20 february 2011 63°14.6´ s 58°46.3´ w 2.2 33.9 117 15 4 20 february 2011 63°47.5´ s 59°26.0´ w 2.2 33.8 163 9 12 21 february 2011 63°51.5´ s 60°15.5´ w 2.3 33.9 201 11 5 24 february 2011 62° 47.2′ s 60° 12.3′ w 2.4 33.9 254 15 14 24 february 2011 62° 52.4′ s 60° 35.6′ w 2.2 33.9 214 9 4 25 february 2011 62°32.3′ s 59°17.4′ w 2.3 33.8 147 14 16 27 february 2011 62° 43.0′ s 56° 32.0′ w 0.5 34.2 202 5 12 27 february 2011 62° 43.2′ s 56° 29.8′ w 0.6 34.1 222 6 8 27 february 2011 62° 45.6′ s 55° 37.2′ w 0.8 34.1 188 12 14 anumber of fish collected on each collecting date. 2 g. blasina et al. prey were identified to the lowest possible taxonomic level according to boltovskoy (1999) and each prey item was counted and weighed (±0.01 g). the importance of each prey item was calculated with the index of relative importance (iri) from the equation iri = %o × (%n + %w), where %o is frequency of occurrence, %n is percentage by number and %w is percentage by wet weight (pinkas et al. 1971; hyslop 1980). iri values were thus standardized to 100% (% iri) (cortés 1997). for the statistical analyses, prey items were grouped into main taxonomical groups. ontogenetic and areas-related changes in diet were assessed using multivariate analysis on the number and weight of the main prey categories consumed. a non-metric multi-dimensional scaling of bray–curtis similarity measures (zuur et al. 2007) was performed to order fish in a two-dimensional plane according to their relevant diet similarity. the relative and interactive effects of ontogenetic stage and areas were tested by a two-way np-manova using bray– curtis distances with 10 000 permutations of the data matrix (anderson 2001). if significant differences were detected, a posteriori pairwise comparisons were made (anderson 2001). all statistical analyses were performed using r statistical software (r development core team 2012). feeding strategy, niche width contribution and dominance of each prey category in the diet of l. nudifrons were assessed with a modification of the costello graphical method (costello 1990; amundsen et al. 1996). in the graphical method, prey-specific abundance (%p) is plotted against the frequency of occurrence (%o), providing a two-dimensional diagram (amundsen et al. 1996). the number of each prey taxon was used to calculated %p: %p : pa i.pa t � � � 100 (1) where p is the prey-specific abundance, ai is the abundance of prey i in stomach contents and at is the total prey abundance considering only those predators in which the prey i occurs. in accordance with amundsen et al. (1996), prey importance is represented by the diagonal set from the lower left to the upper right, with dominant prey at the upper and rare prey at the lower end. prey located at the upper right of the diagram would indicate a narrow niche breadth (i.e., a specialized predator), but if most prey points are located along or below the diagonal, the trophic niche breadth would be broad (i.e., generalist predator). prey located on the upper left corner of the graph indicate specialized individual predators, while prey on the lower right corner are eaten occasionally by most individuals in the population (fig. 3). this graphical method was performed for each area and ontogenetic stage. the tr of l. nudifrons, was estimated for the whole population, size class and sampling area, according to cortés (1999), as: tr : 1 þ xn j�1 pj � trj ! (2) where trj is the tr of each prey item and pj is the proportion of each prey item in the fish diet. the trj values for each prey item were obtained from cortés (1999), pauly et al. (2000) and ebert and bizzarro (2007) (table 2). anova was used to examine the tr differences and a posteriori pairwise comparisons were made with a tukey honest significant difference test (zar 2010). results the vacuity index of l. nudifrons was relatively low in both areas, being 7.65 and 9.71% off the ssi and the ap, respectively. stomach repletion index was moderate, 1.58 ± 0.95 off the ssi and 1.69 ± 1.02 off the ap, and no significant differences between them were found (t = 0.778, p value = 0.437). diet composition of l. nudifrons showed higher prey numbers in the ssi than figure 2. length–frequency distributions of 247 individuals of lepidonotothen nudifrons with stomach content from the ssi and the ap. polar research 3 in the ap, yielding 26 and 20 prey taxa, respectively. the most important zoological categories in both areas were amphipods, isopods, copepods, polychaetes and euphausiids (table 3). some of the main prey items exhibited considerable variation between areas and ontogenetic stages. in the ssi, the most important prey items in juveniles´ diet were calanoid copepods, followed by the isopod serolis sp., polychaetes and amphipods, while in adults´ diet, amphipods and isopods showed the highest importance, followed by euphausiids and polychaetes. off the ap, in contrast, the main food items in the diet of juveniles were amphipods and cyclopoid copepods, while in adults, the euphausiid euphausia superba showed higher importance, followed by amphipods, polychaetes and isopods (table 3). based on the numerical abundance of prey categories, individuals of l. nudifrons showed a clear separation between ontogenetic stages, but there was no clear trend between areas. juveniles of each area were segregated, while the adults overlapped each other (fig. 4). the np-manova test (for both number and weight) evidenced an interaction between ontogenetic stages and areas, where only juveniles showed significant differences in their diet (table 4). the feeding strategy of l. nudifrons seems to be both generalist (for prey positioned in the lower part of diagram) and specialist (for prey positioned in the upper part of diagram). considering the general population in both areas, the high prey specific abundance and low occurrence of copepods, amphipods and euphausiids indicates a high between-phenotype component, with different individual groups relying on a small number of prey items which are different for each group (fig. 5a, b). however, when ontogenetic stages and sampling areas were considered separately, l. nudifrons showed a more mixed strategy, varying between predators specializing on one prey and several individuals in the population eating several different types of prey. in juveniles´ diet, amphipods and copepods were the dominant prey items; however, a different pattern was detected in the frequency of these prey from each area. amphipods were more frequently consumed off the ap than off the ssi and isopods were more frequently consumed off the ssi than off the ap (fig. 5c). adults’ diet in both areas was dominated by euphausiids and amphipods (fig. 5e and 5f). tr for the total population of l. nudifrons was 3.34 ± 0.03. ontogenetic differences were found in tr (anova f value = 2130; df = 3 and 396; p value = 0.0002), pointing out an increase of tr with fish size (juveniles´ tr = 3.22 ± 0.01; adults´ tr = 3.51 ± 0.01; t = 84.79, p value < 0.001). there was no difference in tr between areas for juveniles (t = 2.004, p value = 0.860) as well as for adults (t = 1.453, p value = 0.551). discussion this study represents a comprehensive assessment of the feeding ecology of l. nudifrons off the ssi and the ap, and the first evaluation of the effect of the ontogenetic variability in diet composition, feeding strategy and tr. the size range of individuals sampled in the ssi and the ap was similar to those previously reported from the ap (daniels 1982), south georgia and the south orkney islands (targett 1981). the low iv and the moderate isr of l. nudifrons observed off the ssi and the ap during summer are in agreement with those mentioned for l. larseni in the same study area (curcio et al. 2014), for l. squamifrons in south georgia (gregory et al. 2014) and elsewhere for other notothenioids (bushula et al. 2005; barrera-oro & winter 2008; moreira et al. 2014). consisting mainly of polychaetes, gammarian amphipods, isopods, copepods and krill, the food preferences of l. nudifrons found in the present study agree with those observed by several authors (targett 1981; takahashi & iwami 1997; barrera-oro 2003; casaux et al. 2003). however, l. nudifrons presented spatial differences in diet composition among different areas: figure 3. explanatory diagram for the interpretation of feeding strategy, niche width contribution and importance of prey items. isp: individual specialization of predators; pesp: individuals in the population eating several different prey items. modified from amundsen et al. (1996). table 2. trj of lepidonotothen nudifrons prey items. prey items trj reference polychaetes 2.6 ebert & bizzarro 2007 molluscs (excluding cephalopods) 2.1 cortés 1999 pycnogonids 2.5 cortés 1999 copepods 2 pauly et al. 2000 ostracods 2.25 ebert & bizzarro 2007 amphipods and isopods 2.52 cortés 1999 euphausiids 2.25 cortés 1999 4 g. blasina et al. isopods and calanoid copepods were more consumed off the ssi than in the ap, while cyclopoid copepods were more consumed off the ap than in the ssi. additionally, other regional differences also were reported by targett (1981), who found that l. nudifrons preyed on errant polychaetes, shrimps, fish and mysids off south georgia, and amphipods, isopods, sedentary polychaetes and cumaceans off the south orkney islands. in contrast with targett (1981), shrimps, fishes, mysids and cumaceans are absent in the diet of l. nudifrons off the ssi and the ap. such spatial differences might presumably be due to different local abundances (i.e., availability) of potential prey species. although the relative abundances of the major suprabenthic and zooplanktonic taxa (i.e., mysida, amphipoda, cumacea, isopoda and copepoda) are comparable, they are highly variable in the investigated areas (linse et al. 2002; lörz & brandt 2003; calbet et al. 2005; rehm et al. 2007; san vicente et al. 2007). table 3. juvenile and adult diet composition of lepidonotothen nudifrons caught off the ssi and the ap shown as number of individuals (n), percentage frequency of occurrence (%o), percentage by number (%n), percentage by wet weight (%w) and per cent index of relative importance (%iri). south shetland islands antarctic peninsula juvenile (n = 72) adult (n = 72) juvenile (n = 55) adult (n = 48) prey items %o %n %w %iri %o %n %w %iri %o %n %w %iri %o %n %w %iri hydrozoa 4.4 0.8 0.9 0.3 nemertea 1.5 0.3 1 0.1 polychaeta 21.5 4.1 17.8 14.8 20.6 5.7 13.3 16.7 13.2 2.3 14 9.1 20 8.5 11.4 13.6 mollusca margarella sp. 3.2 0.5 0.6 0.1 teledonia major 4.3 0.8 1.4 0.4 10 3.7 7.5 3.8 laternula elliptica 4.6 1.6 1.9 0.7 pycnogonida 2.9 0.8 1.8 0.3 3.8 1.6 4 0.6 5 2.2 2.3 0.8 copepoda calanoida 23.1 52 9.8 43.8 1.5 0.8 0.1 0.1 5.7 10 0.7 2.6 5 6.6 0.1 1.1 harpacticoida 3.1 13.7 2.1 1.5 20.8 35.2 4 34.7 ostracoda 7.7 6.4 1.7 1.1 1.9 0.7 0.2 0.1 amphipoda paradexamine fisicauda 4.4 4.8 0.9 1.1 13.2 4.5 10.7 8.5 jassa falcata 13.9 5.5 7.8 5.7 10.3 18 3.7 9.5 13.5 11.3 16.4 15.5 15 10.2 12.6 11.6 cyllopus magellanicus 1.5 0.3 2.5 0.2 2.9 0.5 0.6 0.1 9.4 3.6 9.1 5 8.1 9.5 3.7 3.4 waldeckia obesa 1.5 0.3 0.4 0.1 7.4 6.6 6.6 4.1 1.9 2.6 3.3 0.5 8.5 18.3 6 6.2 gondogeneia antarctica 3.1 1.2 8 0.9 9.4 7.4 6.2 5.4 7.5 5.1 2.1 1.9 eusirus antarcticus 4.4 6.1 2.1 1.5 orchomenella nana 7.4 5 3.4 2.6 bovallia gigantea 8.8 3.2 2.7 2.2 primno macropa 1.5 2.4 0.3 0.2 17 5.8 5 7.8 caprellidea (unidentified) 5.9 2.4 0.5 0.7 7.6 4.8 2.8 2.5 unidentified amphipods 12.3 6.1 9.7 6 14.7 11.1 4.1 9.5 1.9 1 1.2 0.2 2.5 1.5 0.1 0.1 isopoda glyptonotus acutus 8.8 3.4 13.6 6.5 5.7 2.3 2.6 1.2 2.5 0.7 0.4 0.1 glyptonotus antarcticus 4.6 1.5 6.7 1.2 16.3 8.2 11.5 13.6 7.6 3.9 7.8 3.7 7.5 6.6 1.7 2.1 serolis sp. 24.6 5.4 23.4 21.8 16.1 6.4 9.3 10.8 1.9 0.7 1.4 0.2 15 7.3 9.6 8.6 unidentified isopods 9.2 3.2 5.7 2.5 7.4 5.3 3.6 2.8 5.7 1 2.8 0.9 8 1.5 1.8 0.6 euphausiacea euphausia superba 1.5 0.3 4.4 0.4 17.7 5.3 16.1 16.1 3.8 1.3 7.8 1.5 27.5 16.1 29.5 42.7 teleostei 7.5 2.2 11.2 3.4 figure 4. non-parametric multi-dimensional scaling of lepidonotothen nudifrons samples based on stomach content analysis, with both areas and ontogenetic stages superimposed. table 4. results of np-manova testing the effect of ontogenetic stage (juvenile, adult) and area on the number and weight of the main prey items (polychaeta, copepoda, amphipoda, isopoda and euphausiacea) of lepidonotothen nudifrons. prey number prey weight factor df f p f p ontogenetic stage 1 7.1239 0.0001b 12.5467 0.0001b area 1 1.8639 0.0987a 1.5585 0.1421a ontogenetic stage x area 1 3.0257 0.0121b 3.0125 0.0338b residuals 243 juvenile-ap vs. adult-ap 1 4.8065 0.0004b 3.8806 0.0007b residuals 101 juvenile-ssi vs. adult-ssi 1 5.3657 0.0031b 9.7658 0.0001b residuals 142 adult-ssi vs. adult-ap 1 2.4022 0.1245a 1.7202 0.1166a residuals 118 juvenile-ssi vs. juvenile-ap 1 2.6896 0.0294b 2.8106 0.0327b residuals 125 anon-significant differences. bstatistically significant differences (α = 0.05). polar research 5 variations in physical factors such as current direction and speed, sea-ice cover, sediment structure, topography and food supply may cause spatial differences in the composition of assemblages in the southern ocean (san vicente et al. 2009). bonicelli et al. (2008) showed that the region of the ssi is a dynamic area, where the distribution of zooplankton is strongly related to the water masses characteristic of the bellingshausen sea and south-east weddell sea. off the ssi the mesozooplankton community was mostly composed of copepods, dominated by calanoids, whereas in the waters off the ap the dominant copepods were cyclopoids (ayón et al. 1999; calbet et al. 2005). previous studies also showed that isopods are more abundant off the ssi than off the ap (linse et al. 2002; lörz & brandt 2003; san vicente et al. 2007). ontogenetic changes in the trophic ecology of l. nudifrons were observed in both areas, reflected by a decrease in the consumption of copepods and an increase in the consumption of e. superba with fish size. targett (1981) also provided evidence of an ontogenetic dietary change in l. nudifrons at south georgia and the south orkney islands, where polychaetes and cumaceans were preyed upon by juvenile fish, while mysids, shrimps and fish eggs were eaten by adult fish. differences in the diet composition of fish of different sizes have also been noted in other notothenioids from the southern ocean, such figure 5. feeding strategy and importance of prey items in the diet of lepidonotothen nudifrons with stomach content from the ssi and the ap. 6 g. blasina et al. as l. larseni, l. squamifrons, gobionotothen gibberifrons and g. marionensis (targett 1981; takahashi & iwami 1997; bushula et al. 2005; curcio et al. 2014; gregory et al. 2014). in all these species, as well as l. nudifrons, the number of different prey types increased with fish size and may be attributed to morphological constraints (e.g., gape-limited) or the better foraging ability of larger individuals (knox 2006). the diet changes between the ssi and the ap observed only in the juvenile stage could be related to their limited swimming ability (fanta & meyer 1998), which would reduce their movement between areas. the diet composition of juvenile l. nudifrons in ssi mainly comprised amphipod and isopods, as also found by moreira et al. (2014). conversely, the calanoid copepods, which we found to be the most important copepods consumed by juvenile fish, were not found in the previous study (moreira et al. 2014). a high between-phenotype contribution to the niche width was observed when considering the whole population of l. nudifrons in each sampling area, where individual predators had specialized on different prey types and each food category had been consumed by only a limited fraction of the predators. however size classes were separated in the analysis, l. nudifrons showed a more mixed feeding strategy, with different dominant prey for each class and a greater within-phenotype component, with several individuals in the population eating several different types of prey. a similar feeding strategy was described in l. nudifrons off the ap (daniels 1982), where each ontogenetic stage showed half the prey diversity of the whole population. the adoption of different feeding strategies and taking different prey or amounts of the same prey likely reduces intraspecific competition (la mesa et al. 1997). food sharing reflects competition only under conditions of limited resource availability (ward et al. 2006). according to casaux et al. (1990) and knox (2006), during summer there was a high availability of food in this area, which may contribute to reducing intraspecific competition for food (moreira et al. 2014). changes in the dominant prey items in the diet of juveniles could be due to differences in availability and abundance of potential prey at different sites, as well as an opportunist strategy, as suggested by barrera-oro (2003). the tr estimated in the present study for l. nudifrons (tr = 3.34) allowed this species to be characterized as a secondary consumer (tr < 4). this result indicates that, in the trophic structure of antarctic communities, l. nudifrons plays an important role in the energy flow from lower to higher trs, because it is usually preyed by seals, birds and also other fishes (barrera-oro 2002). although an increase in tr related to ontogenetic stage was found in the present study, juveniles and adults were both secondary consumers. unfortunately, the lack of previous data on the tr of l. nudifrons, and other congeneric species, prevents comparisons among them. further studies should focus attention on tr estimation throughout the ontogeny of other species of lepidonotothen in order to provide new insights on the ecological role of each ontogenetic stage within demersal food webs of the antarctic zone. acknowledgements the authors would like to thank to dr mario la mesa and an anonymous referee for their helpful comments that greatly improved early drafts of the manuscript. we also acknowledge to dr juan manuel molina for helpful revision of grammar style. funding this work was supported by the consejo nacional de investigaciones científicas y técnicas (project fondo ibol); dirección nacional del antártico and instituto antártico argentino. geb was supported by a fellowship from the consejo nacional de investigaciones científicas y técnicas. orcid gabriela blasina http://orcid.org/0000-0001-8000-9846 references amundsen p., gabler h. & staldvik f. 1996. a new approach to graphical analysis of feeding strategy from stomach contents data: modification of the costello (1990) method. journal of fish biology 48, 607–614. anderson m. 2001. a new method for non-parametric multivariate analysis of variance. austral ecology 26, 32–46. ayón p., girón gutiérrez m., arones flores k. & quesquén r. 1999. composición, abundancia y distribución del zooplancton antártico en el estrecho bransfield y alrededores de la isla elefante. verano austral 1998. (composition, abundance and distribution of antarctic zooplankton in the bransfield strait and the waters around elephant island. austral summer 1998.) perú antar 9, 47–62. barrera-oro e. 2002. the role of fish in the antarctic marine food web: differences between inshore and offshore waters in the southern scotia arc and west antarctic peninsula. antarctic science 14, 293–309. barrera-oro e. 2003. analysis of dietary overlap in antarctic fish (notothenioidei) from the south shetland islands: no evidence of food competition. polar biology 26, 631–637. barrera-oro e. & winter d. 2008. age composition and feeding ecology of early juvenile notothenia rossii (pisces, nototheniidae) at potter cove, south shetland islands, antarctica. antarctic science 20, 339–341. boltovskoy d. 1999. south atlantic zooplankton. leiden: backhuys publishers. bonicelli p., lopez j., ochoa d., shreeve n. & rachael s. 2008. estructura comunitaria del zooplancton asociada con el fitoplancton y las masas de agua del estrecho bransfield y la isla elefante durante el verano austral del 2006. (community structure of zooplankton associated polar research 7 with phytoplankton and water masses in the bransfield strait and around elephant island during the austral summer of 2006.) ecología aplicada 7, 159–164. bushula t., pakhomov e.a., kaehler s., davis s. & kalin r. m. 2005. diet and daily ration of two nototheniid fish on the shelf of the sub-antarctic prince edward islands. polar biology 28, 585–593. calbet a., alcaraz m., atienza d., broglio e. & vaqué d. 2005. zooplankton biomass distribution patterns along the western antarctic peninsula (december 2002). journal of plankton research 27, 1195–1203. casaux r., barrera-oro e., baroni a. & ramón a. 2003. ecology of inshore notothenioid fish from the danco coast, antarctic peninsula. polar biology 26, 157–165. casaux r., mazzotta a. & barrera-oro e. 1990. seasonal aspects of the biology and diet of nearshore nototheniid fish at potter cove, south shetland islands, antarctica. polar biology 11, 63–72. cortés e. 1997. a critical review of methods of studying fish feeding based on analysis of stomach contents: application to elasmobranch fishes. canadian journal of fisheries and aquatic sciences 54, 726–738. cortés e. 1999. standardized diet compositions and trophic levels of sharks. ices journal of marine science 56, 707–717. costello m.j. 1990. predator feeding strategy and prey importance: a new graphical analysis. journal of fish biology 36, 261–263. curcio n., tombari a. & capitanio f. 2014. otolith morphology and feeding ecology of an antarctic nototheniid, lepidonotothen larseni.. antarctic science 26, 124–132. daniels r.a. 1982. feeding ecology of some fishes of the antarctic peninsula. fishery bulletin 80, 575–588. de witt h.h., heemstra p.c. & gon o. 1990. nototheniidae. in o. gon & p. c. heemstra (eds.): fishes of the southern ocean. pp. 279–331. grahamstown: j.l.b. smith institute of ichthyology. eastman j.t. 2005. the nature of the diversity of antarctic fishes. polar biology 28, 93–107. ebert d.a. & bizzarro j.j. 2007. standardized diet compositions and trophic levels of skates (chondrichthyes: rajiformes: rajoidei). environmental biology of fishes 80, 221–237. fanta e. & meyer a.a. 1998. behavioural strategies for feeding of six species of the antarctic fish family nototheniidae (pisces, notothenioidei) in a tank. antarctic record 42, 227–243. gregory s., brown j. & belchier m. 2014. ecology and distribution of the grey notothen, lepidonotothen squamifrons, around south georgia and shag rocks, southern ocean. antarctic science 26, 239–249. heath m.r., neat f.c., pinnegar j.k., reid d.g., sims d. w. & wright p.j. 2012. review of climate change impacts on marine fish and shellfish around the uk and ireland. aquatic conservation: marine and freshwater ecosystems 22, 337–367. hourigan t.f. & radtke r.l. 1989. reproduction of the antarctic fish nototheniops nudifrons. marine biology 100, 277–283. hyslop e.j. 1980. stomach contents analysis – a review of methods and their application. journal of fish biology 17, 411–429. knox g.a. 2006. biology of the southern ocean. 2nd edn. london: crc press. kock k.h., barrera-oro e., belchier m., collins m.a., duhamel g., hanchet s., pshenichnov l., welsford d. & williams r. 2012. the role of fish as predators of krill (euphausia superba) and other pelagic resources in the southern ocean. ccamlr science 19, 115–169. la mesa m., eastman j.t. & vacchi m. 2004. the role of notothenioid fish in the food web of the ross sea shelf waters: a review. polar biology 27, 321–338. la mesa m., vacchi m., castelli a. & diviacco g. 1997. feeding ecology of two nototheniid fishes, trematomus hansoni and trematomus loennbergii, from terra nova bay, ross sea. polar biology 17, 62–68. linse k., brandt a., hilbig b. & wegener g. 2002. composition and distribution of suprabenthic fauna in the south-eastern weddell sea and off king george island. antarctic science 14, 3–10. llompart f., delpiani m., lattuca e., delpiani g., cruzjiménez a., orlando p., ceballos s., díaz de astarloa j.m., vanella f. & fernández d. 2015. spatial patterns of summer demersal fish assemblages around the antarctic peninsula and south shetland islands. antarctic science 27, 109–117. lörz a.-n. & brandt a. 2003. diversity of peracarida (crustacea, malacostraca) caught in a suprabenthic sampler. antarctic science 15, 433–438. molinero a. & flos r. 1992. influence of season on the feeding habits of the common sole solea solea. marine biology 113, 499–507. moreira e., juáres m. & barrera-oro e. 2014. dietary overlap among early juvenile stages in an antarctic notothenioid fish assemblage at potter cove, south shetland islands. polar biology 37, 1507–1515. okach j.o. & dadzie s. 1988. the food, feeding habits and distribution of a siluroid catfish, bagrus docmac (forsskal), in the kenya waters of lake victoria. journal of fish biology 32, 85–94. pauly d., christensen v., froese r. & palomares m. 2000. industrial fishing over the past half-century has noticeably depleted the topmost links in aquatic food chains. fishing down aquatic food webs. american scientist 88, 46–51. pinkas l., oliphant m.s. & iverson i.l.k. 1971. food habits of albacore, bluefin tuna and bonito in california waters. fishery bulletin. vol. 152. sacramento: state of california, department of fish and game. r development core team 2012. r: a language and environment for statistical computing. version 2.14.2. vienna: r foundation for statistical computing. rehm p., thatje s., mühlenhardt-siegel u. & brandt a. 2007. composition and distribution of the peracarid crustacean fauna along a latitudinal transect off victoria land (ross sea, antarctica) with special emphasis on the cumacea. polar biology 30, 871–881. san vicente c., castelló j., corbera j., jimeno a., munilla t., sanz c., sorbe j.c. & ramos a. 2007. biodiversity and structure of the suprabenthic assemblages from south shetland islands and bransfield strait, southern ocean. polar biology 30, 477–486. san vicente c., munilla t., corbera j., sorbe j.-c. & ramos a. 2009. suprabenthic fauna from the bellingshausen sea and western antarctic peninsula: spatial distribution and community structure. scientia marina 73, 357–368. takahashi m. & iwami t. 1997. the summer diet of demersal fish at the south shetland islands. antarctic science 9, 407–413. targett t.e. 1981. trophic ecology and structure of coastal antarctic fish communities. marine ecology progress series 4, 243–263. ward a.j.w., webster m.m. & hart p.j.b. 2006. intraspecific food competition in fishes. fish and fisheries 7, 231–261. zar j.h. 2010. biostatistical analysis. 5th edn. upper saddle river, nj: prentice hall. zuur a.f., ieno e.n. & smith g.m. 2007. analysing ecological data. new york: springer. 8 g. blasina et al. abstract introduction materials and methods results discussion acknowledgements funding references arrival and pre-nesting period of the snow bunting plectrophenax nivalis in east greenland hans meltofte meltofte, h. 1983: arrival and pre-nesting period of the snow bunting plectrophenax nivalis in east greenland. polar research 1 n s . , 185-198. the first snow bunting males arrive in northeast greenland in early april, 6-8 weeks before nesting and 2 4 weeks ahead of the females. at this time temperatures regularly reach -25 to -30°c and snow storms may rage for days. the living conditions during this long-lasting pre-nesting period and its possible function are described and discussed. based on 781 birds caught. .ringed, and measured, and on observations on phenology, diurnal rhythm, night roosts, etc., it is shown that the age ratio in males is close t o 50/50 first living year/adults, that adult males arrive and occupy territories earlier than first year males, that first-year males have shorter wings and are leaner than adult males, that the birds lose weight during spells of inclement weather early in the season, that diurnal rhythm is apparently governed by direct insolation, that males apparently greatly outnumber females in the populations, and that competition for the optimal territories is probably the selective force behind the prolonged pre-nesting period in males. hans meltofte, zoological museum, uniuersifetsparken i s , dk-2100 copenhagen 0, denmark; december 1982 (revised february 1983). introduction the snow bunting plectrophenax nioalis breeds virtually throughout the ice-free parts of green land. it is probably the most common bird and the only passerine breeding in any numbers in the high arctic. although no racial differences within greenland have been accepted (salomonsen 1951), two distinct populations exist. the snow buntings of high arctic northeast greenland win ter in central eurasia, while those of low arctic southeast and west greenland spend the winter in central north america (fig. 1) (salomonsen 1967, 1981). this migratory pattern probably reflects the origin of the populations. the migra tory divide in north greenland is found some where between thule and peary land (meltofte 1976a), and in the southeast probably a little south of scoresby sund (salomonsen 1981) (fig. 2). some snow buntings, mainly males, winter in southeast and southwest greenland (salomon sen 1967; pihl 1976, and this paper). the male snow buntings arrive in east green land very early in the spring, up to two months before nesting and 2-4 weeks before the females. they appear in high arctic greenland at a time when temperatures regularly reach -25°c to -3o"c, and when severe snow storms may rage for days. based on data obtained from several hundred catches of snow buntings during their pre-nesting period and on observations on phenology, diurnal rhythm, etc., i attempt in this paper to evaluate the living conditions of the birds during this period, and to trace possible reasons for their extremely prolonged pre-nesting period. materials and methods in addition to already published arrival data, i have used first observation dates collected by weather station crews in east greenland in 1974 and 1975. large numbers of snow buntings were caught for ringing at angmagssalik by stig jiirgensen in 1974-76 and bjdrn christensen in 1975, at kap tobin (scoresby sund) by myself in 1974 and by bjdrn christensen in 1976, and at danmarks havn by myself in 1975 (see table 2). most birds were caught in cage traps in the spring with grain and seed for bait. the birds were collected when a sufficient number had been trapped. very often some hours passed between each inspection of the traps. as far as possible birds were sex and age determined on criteria given by sv'ensson (1975) (see further below), 186 hans meltofre ~~ fig. 1 . supposed wintering areas (hatched) and main migratory routes of greenland snow buntings (after salomonsen 1981). recoveries of birds ringed in east greenland are plotted. open circles: autumn and winter: dots: recoveries during spring migration. all recoveries east of the atlantic are of birds ringed at danmarks havn and daneborg in northeast greenland. those from canada were ringed at angmagssalik i n southeast greenland and wings were measured flattened and straightened. a t danmarks havn all birds. including retraps. were weighed with a 1oog spring balance. observations were made o n daily numbers, diurnal rhythm. roosting. etc.. espe cially at danmarks havn in 1975. according t o svensson (1975), snow buntings in their first year of life can be age determined by the extent of black or dark colour of t h e longest primary coverts. however. this applies t o euro pean populations, and according t o salomonsen (1931, 1951). the extent of dark colour on primary coverts differs much in subspecies. therefore 22 adult and 130 juvenile and immature specimens in the zoological museum of copenhagen, col lected in greenland in the autumn (adults after 1 august). were analysed with respect to this characteristic. t h e primary coverts a r e not moulted until the post-nuptial moult of the first summer. so birds showing juvenile characters in the autumn should b e representative of first-year birds t h e next spring too, while first-summer birds have attained adult plumage after 1 august. all of the 94 males, except o n e adult and ten juveniles, were clearly distinguishable. thirteen adults showed white or almost white primary coverts, and eighty juveniles had more o r less black longest coverts. o n e adult male and ten juveniles had broad black tips on the longest primary coverts. thus, in accordance with svensson (1975), there is a little overlap (about 10% being inter mediate). t h e criteria given are valid for males in greenland populations, too. in females, eight adults and fifty juveniles all showed dark or pre dominantly dark longest primary coverts. although a certain difference could b e seen between the two groups, t h e primary coverts could not be used for age determination of female snow buntings in greenland. according to the european criteria, nearly all greenland females should b e in their first living year. a certain number of errors, or at least differ ences, may be involved in the present material in the observers' separation of adult, first-year, and unageable males. snow bunting arrival and pre-nesting period 187 danmarks havn hochstetter forland aputi teq p"i fig. 2. map of greenland showing main localities mentioned in t h e text and in table 1. results arrival t h e first snow buntings arrive in south and west greenland in late march and early april, earlier now than in the last century (salomonsen 1951, 1967). in east greenland, from scoresby sund and northwards, the first observations are usually made in the first o r second week of april (table l ) , but in areas with few birds (e.g. peary land) or in late seasons (e.g. germania land 1939) n o birds a r e seen until late april or even early may. t h e snow buntings in southeast greenland belong to the west greenland population, and arrive a little earlier than those further north. except for possible wintering individuals, the first birds at angmagssalik are usually seen in march (table 1). t h e early arrival at this place compared to most other areas in greenland (salomonsen 1951) could be caused by migrants to iceland over-shooting their goal during spring migration. t h e only reported observation of direct immi gration was that of four birds arriving from the east-northeast at havgirds 8 (80"n) in northeast greenland on 25 april 1970 (sirius pers. comm.). the first arrivals are males; the first females are not seen until late april or early may. at danmarks havn (fig. 3) and daneborg, the main influx of males takes place in late april and of females in early o r mid may (rosenberg et al. 1970; meltofte 1975, 1977). according t o recoveries of birds ringed mainly during this study, spring migration is speedy. four recoveries from the archangelsk region in the northern soviet union are dated 8-20 april, and four recoveries from northern norway a r e dated 6-25 april (see fig. 1). southeast greenland birds have been recorded o n newfoundland until 20 april (see luttik & wattel 1979; o r r e t al. 1980). a t bod0, northern norway. flocks of several hundred (perhaps up to 10,000) individuals occur in april (j. fjeldsi, unpubl. data; see vincent & bedard 1976). the first flocks appear in late march. they reach a peak just after mid april and disappear in early may. this is closely in accordance with the arrival pattern for high arctic greenland. annual time variation in first arrivals cannot be determined by weather conditions in high arctic greenland itself. as the birds have to fly more than 1500 km non-stop across the sea from northern norway; only the climate in the winter quarters and along the route can influence the progress of migration. danmarks havn is located in an extremely favourable kettle-hole where flocks of snow bunt ings gather, particularly around the weather sta tion, in april and may during the pre-nesting period. pre-nesting concentrations in april were also observed a t daneborg (conradsen 1957; rosenberg et al. 1970), but in less favourable areas like peary land (johnsen 1953) and kap tobin (meltofte 1976b), only few birds were seen in april and larger numbers were not observed until early or mid may. a t danmarkshavn weather station, the num bers of birds vary with the weather conditions 188 hans meltofte snow bunting arrival and pre-nesting period 189 tuble2. sex and age composition of snow buntings caught for ringing at danmarks havn. kap tobin. and angmagssalik in april and may 1974-76. (fig. 3). on days with new snow and/or strong wind, large numbers of birds are attracted by the favourable feeding conditions near the houses where a very lush vegetation is found. in 1975 there was even plenty of food in the traps. on some days the number of individuals ringed out numbered the number of birds counted. on 23 april 1975, for instance, up to 85 snow buntings were counted at one time, while 109 individuals were caught in the traps. after this date, most of the birds caught already carried rings, but after a new snow storm on 12-14 may, many new individuals appeared (fig. 3). a g e composition in males table 2 shows that about half of the age-deter mined males were first-year individuals, and that the proportion of adults apparently decreased from april to may (only statistically significant for angmagssalik: 2-test: p < 0.01). this may indicate both an earlier arrival of the adults, as already suggested by salomonsen (1951) and conradsen (1957), and an earlier dispersal (see below). the proportion of unidentified individ april % may % total % danmarks havn da" adult dd 1st year dd total dd/?p undet. kap tobin: dd adult dd 1st year dd total pp d d / p p undet. pp 65 51 25 41 90 48 62 49 36 59 98 52 180 64 244 6 12 18 2 1 3 56 44 56 44 . 72 56 72 56 149 149 97 97 angmagssalik. dd adult 85 71 59 51 144 61 dd 1st year 35 29 57 49 92 39 dd total 120 130 250 pp 2 12 14 dd/9 p undet . 3 3 6 uals includes both intermediately coloured birds and birds not age-determined. the sampling may not be fully representative, however, as first-year 0 r p c d q ~ y i ~ s l ~ o m t h r some do) r c r o p t u r e r from 1 j r r i l n ~ 8 $ doys 1 holes rinqcd i m o i c r r i n g e d rarch ~ d ~ ~ i d u d ~ rought l o t d r l w e d 150 100 fig. 3. snow buntings at danmarkshavn weather station in april and may 1975. lower part: daily numbers os birds recorded. snow fall and heavy wind are indicated. *: snow, (*): showers of snow, snow fall part of the day. or drifting snow.: +: about 1.5 knot wind per arrow. the proportion of females to males was prior to mid may were clearly not sufficiently recorded. as individual females were caught from 22 april (see upper part). i n 1970 the main 50 * n hole, rn icm.1er estimated only, and females 50 10 rn i immigration of females started 10 15 20 25 30 1 4 about 5 may (meltofte 1975). april may 190 hatis :melrofie %he 3 ,age c o r n p ~ b ~ t i o n ot ,no\\ bunting, caught i n good and inclement wenlher a t danniarks h a \ n in april a n d &la! 1975 (days n i t h inclernmt \ \ r a t h e r t h o a n in flg. 3. onl! first-rlms caught rndi\~iduala incliidcll. 1 birds may be trapped more readily than older individuals: first-year birds were retrapped more often and over longer periods than adults. table 3 shows that the proportion of adults increased in inclement weather. especially in ma!,. and that the proportion of adults was much lower in good \veather periods in may than in april. further confirming that adults disperse ear lier than first-year birds but rnal’gather into flocks again during spells of bad weather. however. due to the limited materials. these differences do not reach full statistical significance ( f t e s t ) . as table 3 only includes first-time caught birds. the inclement weather sample may be the most rep resentative for the age composition i n male snow buntings i n general. indicating a close to fifty-fifty first-year,adult ratio for males in the spring. this ratio fits in well with the age composition of 34 snow buntings ringed as pulli in greenland and recovered the following year in greenland (salomonsen 1067). fifteen were found as one year alds and nineteen as older birds. indicating that roughly 4(l50rk of the summer population are one-year old birds. custer k: pitelka (1977) present similar \,slues for the lapland bunting cnlcrrrirrs ir7pporiicir.s in arctic alaska. apparently the single trap catches at danmarks h a w were predominated by either first-year or adult birds. indicating that the two age groups stayed in more or less separate flocks. unfortu nately this was not tested. wing riieasiiretnents wing measurements of 921 snow buntings from east greenland are presented in table 4. males have significantly longer wings than females (stu dent‘s t-test: p < 0.01), and adult males have sig nificantly longer wings than first-year males ( p < 0.01). t h e material shows no statistically significant differences between the three trapping sites. body weights mean body weights of 259 first-time caught snow buntinss at danmarks havn are presented in table 5 . males were heavier than females (stu dent’s t-test: p < 0.01 j . adult males were heavier than first-year males ( p < 0.05), males caught in april were 4.8% lighter than males caught in may. a n d males caught during spells of inclement weather in april were 3.9% lighter than those caught in good weather periods. this was obviously not the case in may. and the difference between males i n april and may is less pro nounced (1.9% j . when considering only birds caught in good-weather periods. while the differences in body weight of adult males, first-year males, and females are statisti cally significant. the differences between april and may and between good and inclement weather d u e to great variance and small samples d o not reach full statistical significance. these weights cannot be said to be fully representative, however. as lean and hungry individuals may be more easily caught: on the other hand. they had access to large amounts of food once inside the traps. but the relative differences should at least be indicative. t h e snow buntings seemed nervous and fed v e r y eagerly in poor-weather periods. tirhlr 4 \ v m p mcdcurcnicnts ( ~ n rnrn) of $ n o \ \ h u n t m g s caught at danniarks h a m . k a p t o h ~ n . a n d a n g m a p a a l i k during lu’4-76 ( a t d m n i d r b h.i\n a n d kap tobin onl! hirdr. from spring m o n t h 3 april to june included. while material from a n p n c i g s d i h i n i l u d c \ spring and autumn. j u h t o septcmher. rncasurcrnenta.) danmarkz h d \ n k a p tobin angrn;igssoiik \ k a n s . d . s \ l e a n s . d n \lean s . d . rv snow bunting arrival and pre-nesting period 191 g. * 1 5 r10 toble 5 . body weights (in g) of snow buntings caught in good and inclement weather (see fig. 3) at danmarks havn in april and may 1975. only first-time caught individuals included. for sample size, see tables 2 and 3. april may sex weather age mean s.d. mean s . d . adult 41.9 4.9 (42.8) crd good 1st y . 40.4 5.1 40.9 4.0 total 40.7 4.9 41.5 4.3 adult 40.0 4.9 42.0 4.7 dd inclement 1st y . 38.5 4.7 41.5 4.6 total 39.1 4.8 41 7 4.2 0'6 total 39.6 4.9 41.7 1 4 99 total 34.6 4.9 . . . . . . . . . . . . . . . . . . . . . . . . " . . . . .".. . . . . . . . .. . . . of the 259 snow buntings caught at danmarks havn during the pre-nesting period in 1975, 144 were retrapped 572 times. individual birds were retrapped up to 33 times and up to 26 days after ringing, many being caught several times (max imum seven) in one day, especially during incle ment weather. but the different age and weight groups showed large differences in this respect. including retraps on the day of ringing, 71% of the first-year males were retrapped, but only 50% of the adults (?-test: p < 0.01). when initially caught, adults and first-year birds retrapped later on weighed respectively 5 % and 9% less than birds caught only once (p < 0.05 and p < 0.01, respectively, t-test). fig. 4 shows that retrapped males rapidly gained weight during the week after ringing, but lost weight during the first day. initial weight loss was probably due to the severe weather prevailing when the majority of these birds were caught, and the succeeding increase reflects the better conditions during the following days, and espe cially perhaps the optimal feeding possibilities inside the traps. twenty-one first-year males retrapped more than eight days after ringing ended up with a mean weight of 46.6g (range 36-56g), or 17% more than all first-time caught first-year males (p < 0.01). this final weight seems to be the maximum mean weight for first-year snow bunting males during this period, but may perhaps only be attained by birds having access to unlimited food resources (see below). these individuals specialized in feeding in the traps, and were only caught when taken by sur prise. otherwise they easily found their way out of the traps again. a few birds were so exhausted when caught, -5 . -10 that they probably did not survive; no males weighing less than 27 g were retrapped. -ii+..-. . ..._" .. .f" . . . . . . . . . . diurnal rhythm and night roosts fig. 5 shows that during the pre-nesting period at danmarks havn in 1975, the snow buntings arrived and left the feeding area around the weather station and the traps almost symmetri cally around solar zenith. no correlation was found with the daily air temperature cycle two metres above the ground. thus probably the 192 hans meltofte fig. 5. time of first and last observations of snow buntings on a number of days between 14 april and 19 may 1975 at the feeding areas around danmarkshavn weather station (solid dots) together with the mean daily temperature oscillation per ten-day period (solid lines). small dots indicate a few birds present, large dots mnre than ten birds present. time5 given are local solar times. i.e. one hour after gmt. during period 11 april to 20 may maximum sun height increased from 21.5" to 33.2" over the horizon and the minimum height from -4.9" to 6.8". fig 6. termometerfjeldet ( 138 m above sea level) at danmarks haln u,ith the main night roost circled (26 april 1975) even the cliffs a little higher to the right were sometimes used. s o t c the '5emi-snow-cover' o n the plain in the foreground. hg. 7. the main night roost on termometerfjeldet with ten snon buntings sitting in cracks and on the snow ridge in front of the cliff (see fig. 8 ) . most birds flew off as i approached the cliff (26 april 1975). snow bunting arrival a n d pre-nesting p e r i o d 193 from quebec in canada, vincent & bcdard (1976) report similar night roost scrapes made by snow buntings on the lee side of snow drifts in the winter, but only when temperatures fell below -7°c. h e r e the distance between each scrape was about 2 s m , however, and rarely less than 3 0 c m . huddling did not occur even under extreme physical conditions. during snow storms, snow buntings, like tetraonids, may let themselves be nearly covered with snow (in norwegian: dokke) behind the edge of snow drifts (meltofte 1975; see also bagg 1943; parmelee 1968; marjakangas 1981; thiede 1982). t h e very low number of birds present on the weather station during the severe snow storm (45 knots) on 13 may was thus caused by the fact that most birds would b e seeking shelter and many probably remained on night roost throughout the day. the birds flew to and from the roosts in groups of up to ten, and very often fed nearby for some time after arrival. song, flight pursuits, and other antagonistic displays were often performed at the roost. o n 24 april 40-50 individuals were present, about 35 o n 26 april, and about 20 on 8 may; direct insolation and thereby the conditions near the ground a r e the most decisive factors for the diurnal rhythm of the birds. at danmarks havn the sun is in the sky for 24 hours a day from 25 april; the average daily temperature oscillation in 1975 decreased from only 5°c in mid april to about 3°c in mid may, reaching a maximum dur ing the afternoon and a minimum during the early morning hours (fig. 5). unfortunately, no measurements of the microclimate are available, but the daily oscillations are much more pro nounced near the ground. t h e snow buntings from the area at danrnarks havn roosted o n southwest exposed cliffs o n termometerfjeldet about 900 m northeast of the weather station (figs. 6 and 7 ) . the cliffs were exposed to t h e sun until 09:15 p.m. and again from 09:15 a . m . (local solar times). the prevailing winds (and storms) at danmarks havn blow from northern and northwesterly directions. the birds sat in narrow cracks in the cliffs (fig. 7) and in scrapes made by the birds in the snow just behind the ridge of a snow fan half a metre in front of o n e of the cliffs (fig. 8). t h e amount of droppings indicates that these sites were used regularly. fig 8 . vcrtlcal photo of the scrapes behind the edge of the snow drift in front of the main night roost on terrnometerfjeldet on 26 april 1975. 194 h a n s meltofte about the same numbers as estimated a t the weather station on the corresponding days. by 21 may n o birds were present at the roosts; thus, after dispersal and mating, the snow buntings did not roost there any more. similarly, a communal roost o n rathbone 0 near scoresby sund, occu pied by 80 snow buntings o n 12 may, was left by 26 may (ko d e korte in litt.). parmelee & hlac donald (1960) made similar observations on ellesmere island, but elsewhere communal roost ing, especially involving males, has been reported throughout t h e breeding season (summers 1971, 1973; swann 1975). dispersal and breeding phenology snow buntings were heard singing sporadically from arrival at danmarks havn in mid april 1975 and encounters took place on the feeding sites. especially around the traps. at angmagssalik, where t h e first birds usually appear as early as march. singing does not start until mid april (petersen 1908). song intensified from the last days of april. as the males approached full nuptial plumage. it was my impression that newly arrived (unringed) males had a less developed nuptial plumage than 'residents'. age differences may also be involved here. by mid may most males were in nuptial plumage, the bills having turned from yellow t o dark grey. but a few were still more or less in winter plumage. from then on loose flocks were more frequent in the lowland around the weather station. males highly out numbered females in these flocks, while females increased to more than 50% of the birds present at the weather station (fig. 3). pairs appeared from about 20 may when t h e males had attained almost full nuptial plumage with only narrow light edges o n black feathers. in late may the number of birds present in the lowland a t danmarks havn reached a peak with more than o n e hundred individuals. most birds still stayed in loose flocks. of which 76% of 165 sex-determined individuals were males. during t h e last few days of may flocks decreased in size and number: most birds appeared in pairs. and many males sang intensively. during spells of bad weather. however. flocks formed again. thus, during three days of severe snow storm from 16 t o 18 j u n e . u p to 100 indi viduals gathered at the weather station; 80% of these were males. t h e birds sought shelter, some were nearly covered by snow. and others fed intensively. o n e fresh egg was found o n the ground in open terrain. in 1975, egg laying took place about mid june at danmarks havn. t h e first fledglings left the nests 12-13 july, the bulk of them about 16 july. this is in good accordance with statements from most of the high arctic greenland, while most young in south and west greenland fledge in late june (salomonsen 1951). given a fledging period of 10-12 days, an incubation period of 12-13 days (manniche 1910; parmelee & macdonald 1960), and one egg laid per day (tinbergen 1939), most clutches were initiated in mid june and most young hatched during the last days of j u n e and the first days of july. earlier breeding has been found o n a num ber of occasions in northeast a n d north green land. pairs have been seen several times from early may, and nest building has been observed in mid may. a t scoresby sund a n egg was found o n 1 june and hatched pulli seen o n 22 june (pedersen 1930). a t daneborg, a clutch was hatched on 19 j u n e , 1975 (meltofte 1977), and newly hatched young were found on 20 j u n e 1969 at danmarks havn (meltofte 1975). in peary land, the northernmost land area in the worl'd, fledglings have been seen as early as on 1 , 4, 6, and 7 july of 1964, 1968, 1912, and 1949, respec tively (freuchen 1915; johnsen 1953; r ~ e n 1965; andersen 1970). breeding may b e considerably delayed under extreme conditions. i n 1939, pedersen (1942) found that the snow bunting flocks did not break u p until the second half of j u n e , and many indi viduals died during the pre-nesting period. discussion t h e most striking feature of t h e snow bunting's pre-nesting period is t h e fact that the males arrive 2-4 weeks in advance of the females. they appear in high arctic greenland at a time when temper atures regularly reach -25 to -3o"c, when severe snow storms a r e common and most of t h e ground is snow covered. not until late may d o maximum temperatures regularly exceed zero. t h e main reason why snow buntings a r e able to survive at all in these extreme high arctic environments is probably the same as for many o t h e r animals: the fact that regular storms blow the snow off large areas, so that vegetable food is available through o u t the year. large areas a r e only covered with snow bunting arrival and pre-nesting period 195 period lasts 2-5 weeks. in addition to time for competition for favourable breeding territories, for mating, etc., this period may be needed to give the females time to adjust the onset of breed ing to the diversified local and annual environ mental conditions, i.e. the progress of spring (meltofte 1976a). this can hardly be the reason for the 6-8 weeks pre-nesting period for males, however, especially as they are prepared to copu late during a much longer period than the females (tinbergen 1939). still another feature is striking. there are several indicia that males outnumber females in snow bunting populations. bay (1894) observed that the great majority of birds seen at scoresby sund were males, and similarly pedersen (1926) noted ‘eine gewisse uberzahl bei den mannchen’. these statements might have been based on observations during early spring when many snow buntings congregate around houses, etc., and only few females are present. but summers (1973) found this obliquity even in late summer. out of twenty snow buntings feeding scattered on the tundra, fourteen were males. in late may 1975, at a time when all females had arrived and most males should be defending territories, 76% of 165 sex-determined individuals feeding in loose flocks at danmarks havn were males. among the juv eniles kept in the zoological museum of copen hagen, collected in greenland in the autumn, when biased sampling among juveniles is less likely than in the spring, 64% are males. of 38 northeast greenland juveniles 26 are males. in peary land (meltofte 1976a) and on hochstetter forland (meltofte et al. 1981) several male snow buntings have been heard singing in territories where females were never seen. the males left by late june or early july without any sign of breeding. even on baffin island in canada single and small groups of unmated males were seen in unfavourable areas (watson 1957). all of this indicates a certain surplus of males in the popu lations, and that they establish territories in mar ginal areas. this further supports the idea that strong competition exists between the males both for favourable territories and for a mate at all. salomonsen (1951) states that one-year old males breed. their later arrival, however, and dispersal and poorer physical condition in general (lower weight and shorter wings), make it likely that they constitute the main part of the marginal unmated males. similarly custer & pitelka (1977) found that what could be called a semi-snowcover, through which the seed spikes of grasses and sedges appear. from the time the first snow buntings arrive early in april, the heavy insolation causes much of the thin snow cover to evaporate. by absorbing the insolation the exposed seed spikes and other tall vegetation create snow free holes in the snow around them, which further increases the feeding possibilities for snow buntings. after all, the climate is ‘milder’ in april than in march. spring actually starts in early april when mean temperatures rise to above -20°c compared with -20 to -30°c throughout march. many authors have speculated about the func tion of the long-lasting pre-nesting period of the snow bunting (salomonsen 1972). i am unable to provide anything but speculations either. great differences in population densities exist, varying from more than five pairs per square kilometre in highly favourable areas, to nearly none or at least exceedingly thin populations in large. barren, ‘rock-less’, or late thawing areas. there is probably hard competition for the most favourable breeding sites. the males start to sing and occupy territories soon after arrival and long before the arrival of females. n o doubt the optimal territories are occupied first, the com petition for them being perfectly illustrated by the well developed display and fight system described in detail by tinbergen (1939); some males even succeed in getting more than one female. during all of the pre-nesting period the birds gather into flocks again as soon as unfa vourable weather conditions prevail. the birds often alternate between territorial and flock behaviour in the course of one single day (tin bergen 1939; rosenberg et a]. 1970). the majority of the less favourable breeding areas are not populated until early, mid or even late may, when the majority of the birds having spent the pre-nesting period in favourable areas like the kettlehole at danmarks havn, leave for other breeding areas. only a small proportion of the locally breeding birds carried rings. thus it seems advantageous for the male snow buntings to arrive and occupy the most favourable territories as early as possible, but not so early that the advantage of optimal territories is coun teracted by a too heavily increased mortality risk. the lacking pre-nuptial moult of the snow bunt ings (salomonsen 1951) may be part of the adap tion features making this strategy possible. for female snow buntings the pre-nesting 196 hans meltofte 'floating' males of lapland buntings were a con spicous sight at point barrow after about 20 june. and that they included an unknown proportion of non-breeders believed to have been mainly first-year individuals. the males are bigger and heavier than the females and should thus be better equipped to sustain periods of inclement weather during their early pre-nesting period. apparently they are able to maintain close to normal body weight even in april, but only under good weather conditions. during spells of bad weather in april weights drop, illustrating the unfavourable living condi tions that male snow buntings have to face after arrival. the body weights found for pre-nesting males are quite similar to weights found in july. september at mestersvig ( g r e e n & summers 1975). and also fit in well with weights given for both may and august in peary land (mahl hansen 1937: johnsen 1953). bentz ( i n l i t t . ) recently studied staging snow buntings before their departure from northern nonvay. a total of 151 males and 49 females weighed at andoya on 19-25 april 1982 averaged 51.5 g and 34.7 g. respectively. compared to the arrival weights in northeast greenland. this shows a pre-migratory fat gain of at least 30% in both sexes. the pre-migratory weights found by bentz are closel! in agreement with those found during the same period in the spring in captive (outdoor) snow buntings at quebec in canada (vincent 6: b d a r d 1976). h e r e the body weights increased very abruptly in .march and april. from below 40 g to a b o \ e 5 0 g (all birds grouped). mean po3t migration weipht in canada was about 48:. i.e. ver! close to the final weights of the snow buntings in the traps at danniarks havn. even though differences may be found from year to year and from place to place. the snow bunting populations breed highly synchronously. the main part of the broods hatch within a week or so (meltofte 1977; asbirk et al. manuscript). onset of breeding may be triggered by the dis appearance o f the snow. i . e . when the feeding conditions ( o n arthropod prey) are improved for the females prior to and dcring egg laying (see custer 6: pitelka 1977: morton 1978: madsen 1982). this is further supported by the fact that pre-nesting snow buntings weigh significnntly less than artificially fed birds during the same period (vincent & bedard 1976). ultimately onset of breeding may even be governed by the time required for development including post-juvenile moult by the young before autumn migration (asbirk et al. manuscript). furthermore. most young hatch and a r e fed a t the time of the season when arthropod prey is superabundant, i.e. from late june until the second half of july (hussell 1972: meltofte. unpubl.). in northeast greenland song and other terri torial behaviour cease a t the time of hatching by early july. after fledging, family flocks stay together for about 10-12 days when the young are still fed (asbirk e t al. manuscript). t h e males leave. often to more mountainous areas for a very rapid moult during t h e second half of july and early august. during this period they may be almost flightless (see g r e e n & summers 1975). females moult a little later. flocks of u p to 250 individuals may gather in august, the first appear ing in late july, and numbers reach a peak in late august and early september. most adults leave during the first half of september (manniche 1910) and most immatures follow before the end of the month (meltofte 1975). single individuals are seen, however, until late october or even in november and december (bird & bird 1941). population densities in favourable areas have been estimated to about three pairs per square kilometre at mestersvig (vibe 1954; ferns 1978), and more accurately censused to 4.7 pairs per square kilometer at daneborg in 1964 (rosenberg et al. 1970) and 5.6-5.8 pairs per square kilometre at danmarks havn in 1975 (meltofte 1977). a t danmarks havn, however, only 3.3-3.6 pairs per square kilometre were recorded breeding. opti mal breeding sites are rocky 'islands' or boulder screes near early thawing, moist, well vegetated areas. t h e diurnal rhythm registered fits in well with observations made at the same time of the year on ellesrnere island (parmelee & macdonald 1960) and is in relatively good agreement with the diurnal rhythm found in snow buntings during the nesting period at mestersvig farther south in northeast greenland (asbirk & franzmann 1979). t h e daily activity pattern there was highly synchronized with the ground temperature oscil lations. and thereby with arthropod activity. the apparent seasonal increase in duration of daily activity seen in fig. 5 may partly be a result of the increased number of birds present in april (fig. 3 ) . o n a few occasions birds were actually at the weather station throughout the 'night'. a t ny-alesund on spitsbergen the snow bunt snow bunting arrival and pre-nesting period 197 ings were found t o roost during the afternoon and evening hours in j u n e and july, and to leave the roosts around midnight (swann 1975). these results indicate that both the endogenous rhythm and environmental stimuli, such as insolation intensity, weather, temperature and feeding con ditions, may govern the diurnal rhythm (see len nerstedt 1973). summary based on 781 snow buntings caught, ringed, and measured on three different sites in east green land in the spring, and o n observations on phen ology, diurnal rhythm, night roosts, etc., the characteristics and function of the pre-nesting period (that is the period from arrival until start of nesting) are described and discussed. t h e fol lowing main points are emphasized: 1 2. 3. 4. 5. 6. 7. 8. 9. two different populations exist in east green land: o n e in the high arctic northeastern part, wintering in central eurasia, and one in the low arctic southeastern part wintering in cen tral north america together with the west greenland birds. these differences probably reflect the geographic origin of the two populations. males arrive 2-4 weeks ahead of females, and have a total pre-nesting period of 6-8 weeks. among the males there is a close to fifty-fifty adult/first-year ratio. adult males arrive and disperse, i.e. occupy territories earlier than first-year males. first-year males have shorter wings and are generally leaner than adult males. the birds lose weight during spells of inclement weather in april. communal roosting takes place during the pre-nesting period. the diurnal rhythm is probably governed by direct insolation and not by air temperature. t h e prolonged pre-nesting period of the males is probably a result of strong competition between males for the most favourable territories. 10. there are strong indications that males highly out-number females in the populations. the surplus of males probably occupy marginal ter ritories and constitute mainly first-year birds. acknowledggernenrs. i am indebted to stig jiirgensen and bjern christensen for their good work in angmagssalik and kap tobin, to knud fischer, hans christensen. and ulrik capito who did much of the ringing at danmarks havn in 1975, to viggo bloch and jens ole larsen who continued the ringing after my start at danmarks havn in 196%71, to the staffs of the weather stations in east greenland who readily provided the dates of initial observation of snow buntings. to ko de korte for his unpublished data from scoresby sund 1973-75. to p.-g. bentz for providing unpublished data on staging snow buntings i n northern norway 1982. t o the ornithological depart ment of the zoological museum in copenhagen for giving me access to their collections. to finn dalberg pedersen for his help with the statistical analyses, to jon fjeldsd for his critical reading of an early draft of the manuscript, and to lene smith who corrected my english. references andersen, 0. g . n . 1970: ornithological observations on the 5th pearyland expedition in the summer of 1968. with a review. (danish with english summary.) dansk orri. foren. tidsskr. 64, 104-112. asbirk, s. & franzmann, n.-e. 1979: observations on the diurnal rhythm of greenland wheatears oerzanrhe oe. leu corrhoa gm. in continuous daylight. dansk orrz. foren. tidsskr. 73, 95-102. asbirk. s . . franzmann. n:e., greenwood, j . j . d. & sum mers, r. w. manuscript: observations on snow buntings in east greenland. particularly on the daily pattern of activity. manuscript not yet published. bagg. a . m . 1943: snow buntings burrowing into snowdrifts. a u k 60. 145. bay. e. 1894: hvirveldyr. in: den estgr8nlandske expedition u d f m i aarene 1891-92. meddr. grmrzland 1 9 / 1 ) , bird. c. g . & bird. e. g . 1941: the bird, of north-east greenland. ibis i4(5). 11%161. chapman. f. m . 1932: some field-notes on the birds of east greenland. i n watkins. h . g. ( c d . ) : the british arctic air route expedition. geographical journal 79. 193-496. conradsen, f . r . 1957: ornithologiske iagttagelser ved dane borg. n . 0 . grenland. dansk orn. foren. tiddskr. 51. 12 18. custer. t. w. & pitelka. f . a . 1977: demographic features of a lapland longspur population near barrow, alaska. a u k 94, 505-525. ferns. p . n . 1978: general ornithological notes. i n green, g . h . & greenwood. j . j . d. (eds.): joint blokjgicrlexpedirion to north east greenland 1974. dundee universin n . e . greeriland expedition. 152-164. freuchen. p . 1915: rcport of the first thule expedition. scien tific work. birds. meddr. gr@nland 51/12), 4 0 6 4 1 1 . green. g . h . & summcrs. r . w . 1975: snow bunting moult in northeast greenland. bird study 22. 9-17. helms, 0. 1926: the birds of angmagssalik. meddr. gronland hussell. d. j . t. 1972: factors affecting clutch sire in arctic johnsen. p. 1953: birds and mammals of peary land in north koch, l. 1925: nord om g r d d a n d . kebenhavn. lennerstedt, i . 1973: nlght rest during nestling period i n four passerine species under subarctic summer conditions. ornis scand. 4 , 17-23. luttik. r . & wattel, j . 1979: observations of land birds on weather ships in the north atlantic. limosa 52, 191-208. madsen, j. 1982: timing of breeding and reproductive success i n a lapland bunting ca1carius lapponicus population in 5814). 205-274. passerines. ecol. monogr. 42, 317-364. greenland. meddr. gronland 128(6) 198 hans meltofte eqalungmiut nunaat. west greenland. dansk orn foren. t i d w k r . 76. 137-14s manniche. a . l. v. 1910: the terrestrial mammals and birds of north-east greenland. m e d d r . g r ~ l m d 4 5 ( 1 ) , 200 pp. marjakangas. a 1981 : snow buntings plectrophenax nroahs burrowing in the snow ornis fennica 58. 8!+90. meltofte. h . 1975. ornithological observations in northeast greenland between 76"' and 78"oo' n. lat.. 1969-71. ,metidr. grqnland 1 9 1 ( 9 ) . 72 pp. meltofte. h 1976a: ornithological observations in southern pearv land. north greenland. 1973. m e d d r . gronland lmeltofte. h . 197hb: ornithological observations from the scorcsb? sund area. east greenland. 1974 (danish with english summary ) dunik orri foreri. t i d d s k r . 70. 107-122. meltofte. h. 1977: ornithological observations in gerniania land. northeast greenland, 1975. (danish with english sum mar! ) d a m k o r n foren. tidssskr. 7 1 , 81-94. meltoftr. h.. elander. .m. 8hjort. c. 1982: ornithological observation5 in sortheast greenland between 74"30' and 7h"w' s . la!.. 1976. .meddr. grqnland. bioscience3. 53 pp. morton. m. l. 1978: snow conditions and the onset of breeding in the mountain white-crowned sparrow, condor 80. 285 289. mohl-hansen. u . 1947the bird-life in pear! land. xorth greenland. (danish with english summary ) dansk orn f o r e n tidjskr. 43, 109-129, orr, c . . gillis. d . j & valdron. l g . 1980: snow, buntings. lapland longspurs. and othcr passerines in davis strait and labrador sea. 1977-1979. c a n . field .var. 9 4 , 185-187 parmelee. d . f. iy6x: snow bunting. i n bent. a . c. c t a1 (eds.): l i f e himmes of sorrh a m e r i c a n cardinals. gros beaks, bunrings. tohhees. finchei. sparrows. and allies part 3. neu york. parmelee. d. f 8macdonald. s . d 1960. the birds of west-central ellesmerc lsland and adjaccnt areas. .vm. i l i r d . canada bull 109. 1-103. pedersen. a. 1926. beitrige z u r kcnntnis der saugcticrund vogelfauna der ostkusic gronlands .weddr gronland 68131. 14y-zjy. pedersen. a 1930. fortgesetzte beitrage zur kenntnih der saugetier und vogelfauna der ostkuste gronlands. .mrddr. grqnland 77/51. 341-507. pedcrscn. a . 1942 saugeticre und vogel. .meddr. gronland petersen. j . 1908. ornithologiske lagttagelser fra angrnagsalik 205(1), 57 pp. 1 2 8 / 2 ) . 119 pp i aarene 1902-08. dansk orn. foren. tidsskr. 3 , 1-26. petersen, j , 1941 : dagbogsoptegnelser om fuglenes forekomst ved scoresbysund station fra efteraaret 1934 ti1 sommeren 1935. dansk orn. foren. tidsskr. 35. 123-125. pihl. s . 1976observations of birds in southwest greenland, 197-%75. (danish with english summary.) dansk orn. foren. tidsskr. 70. 103-106. roscnberg. n. t.. christensen, n . h. & g e n s b d , b. 1970: bird observations in northeast greenland. meddr. grmnland r w n . u . 1965: ornithological observations on the 3rd peary land expedition in the summer of 1964. (danish with english summary.) dansk orn. foren. tidsskr. 59, 85-91. salornonsen. f. 1931: on the geographical variation of the snow-bunting f p l e c f r o p h e n a x niualir). ibis 13(1), 57-70. salomonsen. f. 1951: the birds of greenlund. copenhagen. salomonsen. f. 1967: fuglene p d gronlund. copenhagen. salomonsen. f . 1972: zoogeographical and ecological problems in arctic birds. p r o c . xvth lnt. ornithol. congr. 25-77. salornonsen. f. 1981: fugle ( a u e s ) . i n salomonsen, f . (ed.): g r o n l a n d s fauna. copenhagen. summers. r . 1971: the diurnal rhythm of snow buntings in continuous daylight. i n smart, i . h . m . & o'brien. r . (eds.): report of the dundee l'niuersih scoresbyland expedition 1970. 51-55. summers. r 1973: the diurnal activity pattern of the snow bunting 1n o'bricn. r . m . g . &greenwood, j . j . d. (eds.): rrporr o,f the unwersily of diindee norrh easr greenland expedirion 1972. 59-60. s\ ensson. l 1975: identificarion guide t o european passerines. stockholm swann. r . l . 1975: communal roosting of snow buntings in spitsbergen. srerna 1 4 . ill-112. thiede. w. 1982: snow buntings plecrropltenar niualis roosting in the s n o w omis fenn. 59. 37-38. tinbergen. n. 1939: the behavior of the snow bunting in spring. trans. linn. soc. .my. 5 . 1-94. tcherniakofsky. p. 1939: contribution a i'etude ornithologique d u scoreshy-sund l'oiseau 9 , 321-363. vibe. c. 1954: gronlands zoogeogratiske undersogelse 1953. bercriiinger uedr@retide g r r n l a n d 1954. i , 74-15. vincent. j . 8: bidard. j . 1976: fat reserves in snow buntings. can j . zoo/. 54. 1051-1063. watson. a . 19.57: birds i n cumberland peninsula. baffin island. can. field nar 7 1 . 87-109. l y l ( 1 ) . 87 pp. calculation of melt pond albedos on arctic sea ice alexander p. makshtas and igor a . podgorny makshtas, a . p. & podgorny, i. a . 1996: calculation of melt pond albedos on arctic sea ice. polar research 15(1), 43-52. an analytical approximation of spectral albedo is derived for a melt pond with a lambertian bottom assuming that rayleigh scattering in the water is small compared to absorption. a monte carlo method is used to verify that scattering can he ignored in the water. this enables us to calculate pond albedos in the 4oc-700 nm wavelength hand using the analytical approximation. model calculations and observations indicate that a step-decrease in albedo is likcly t o occur when a melt pond initially forms, and melt pond albedos i n the visible depend more on the structural and optical properties of the bottom than on the depth of the pond. a . p. makshtus, arctic & antarctic reseurch institute, 38 bering s t . , 199397, st. petershurg, russia; i . a . podgorny, universiry of wushingron, jlsao, p . o . box 354235, seattle, w a 98195, usa introduction melt ponds represent an important component of the arctic climate system. they greatly affect both the surface albedo and redistribution of solar energy in the sea ice cover during the melt season (e.g. maykut 1986; maykut & perovich 1987; barry et al. 1993; ebert & curry 1993; ebert et al. 1995). over the past few decades a large quantity of albedo measurements have been reported for melt ponds (e.g. nazincev 1964; langleben 1971; grenfell & maykut 1977; grenfell & perovich 1984; ivanov & alexandrov 1994; perovich 1994; morassutti & ledrew 1995). the measurements span the entire season and include observations for a variety of ice types and illumination conditions. for example, according to nazincev’s (1964) observations in the central part of the arctic basin, melt ponds having an albedo as low as 0.3 covered up to 45% of the surface. as a result, area-averages albedos of the surface were as low as 0.45 in july. in addition t o empirical studies, the effect of melt ponds on the short wave radiative transfer has been studied using a coupled atmosphere-ocean-sea ice model (jin et al. 1994). despite this considerable effort, there is a need for better knowledge of how solar energy is redis tributed in the ponded ice (moritz et al. 1993). while there do exist some empirically obtained parameterisations for melt pond albedos and radi ative fluxes into the melt water layer (ebert & curry 1993; ebert et al. 1995; morassutti & led rew 1995), a theoretical basis for these par ameterisations is still absent. as outlined by moritz et al. (1993), spectral albedo models for melt ponds must be formulated taking into account ice thickness, melt pond area and thick ness, lead fraction, ice age, salinity and snow characteristics. investigation of how melt pond albedo is affected by each of these parameters will yield an improved understanding of the relationship between summer albedos and melt processes. this paper presents new data on pond albedos in the arctic ocean in the 40g700nm band and describes a method for calculating spec tral albedos of melt ponds. only the visible spec trum is considered because pond albedos in the solar infrared are determined primarily by fresnel reflection and are nearly independent of wave length (e.g. grenfell & maykut 1977). both measured and calculated albedos are analyscd as a function of pond depth. we do not attempt to present a definitive parameterisation of pond albedo that could he incorporated into the sea-ice models. instead, the objectives of this paper are twofold: (1) to increase the understanding of the short-wave radi ative transfer in melt ponds and (2) to develop a forward model that can be applied in estimating 44 the vertical partitioning of solar energy in a melt pond and underlying ice from measurements of pond albedo and depth. a . p . makshtas & i . a . podgorny spectral albedo of melt ponds statement of the p r o b l e m because many details of the inherent optical properties of ponded ice are still uncertain, a priori prescribed spectral albedos of the melt pond bottom are used in numerical simulations of radi ative transfer within the ice layer. the ice is assumed to be optically thick, while the reflec tance distribution of the pond bottom is assumed to be lambertian and independent of the angular distribution of the incident radiance. optical properties of the melt water are postulated to be similar to the optical properties of the clearest water observed in the central part of the arctic basin (smith 1973). the configuration of the model used in this study is shown in fig. 1. the model consists of two plane-parallel layers, hereafter referred to as the water and ice layers. both layers are assumed to be optically homogeneous in the vertical and horizontal directions. spectral albedo (cu) is denoted by the subscript w for the water in the melt pond itself and by the subscript i for the ice at the pond bottom. melt pond depth is denoted the directions defining the incoming and out coming light beams in the atmosphere are expressed by ( p , @ ) , where p is the cosine of the zenith angle and @ is the azimuthal angle. fur thermore, p and p denote upward and downward directions. the direction of the incoming solar beam is denoted by (-k,, &). similarly, the direc by hw. / .c=o z=tw h w ice fig. 1. configuration of the one-dimensional melt-pond model. tions defining the light beams in the water layer are expressed by (q,@), with q and -7 denoting upward and downward directions respectively. the direct solar radiation reaching the air-water interface from above (f,) is refracted into the direction (-qo, 4) in accordance with snell's law where n, is the refractive index of the water. the n, value is taken t o be 1.33 in this study, irrespective of wavelength. we start by considering the monochromatic radiative transfer equation in one spatial dimen sion for the water layer. specifically. ( 2 ) 4n where y and y' are determined by ( 3 ) here, i ( t , ~ , @ ) is the unpolarised diffuse spectral radiance at wavelength a (omitted for brevity) at optical depth t. a, is the single-scattering albedo, x(y) is the phase function, y is the scattering angle (0 y isoo), r ( h ) denotes the fresnel reflection coefficient for the air-water boundary, and f,, is the incident spectral irradiance. as seen from fig. 1, optical depth increases with the depth of the water layer. in addition to eq. ( 2 ) , which governs the trans fer of diffuse radiation, we introduce the transfer equation for direct radiation in the water layer: the direct component of the radiation field is associated with that part of the unscattered solar flux which penetrates through the air-water interface and is attenuated exponentially. the boundary condition at the top of the water layer is given by calciilution of melt pond albedos on arctic sea ice 45 while downwelling radiation at the top of the ice layer is here, t, = (k, + a,,,)lhwl is the optical thickness of the water layer, k~ and ow are the beam absorp tion and scattering coefficients in the water, and r(q) is the fresnel reflection coefficient for the water-air interface. eq. (6) describes the fresnel reflection of the upwelling diffuse radiation from the top surface of the water layer. eq. (7) des cribes the diffuse reflection of the downwelling direct and diffuse radiation from the top surface of the ice layer. it and i j. denote the upwelling and downwelling radiances respectively. because the pond bottom is assumed to be a lambertian reflector, r/ and 9 are omitted in the left side of the problem is formulated as follows: under the assumption that scattering is small compared to absorption, one needs to find an approximate (analytical) solution to eq. (2) with the boundary conditions given by eqs. (6) and (7). the accuracy of the analytical solution must then be estimated for actual rw and a, values. eq. (7). anutyfic solution to the radiutiue transfer eqitation when scattering in the water layer is small com pared t o absorption, the diffuse radiation field is independent of the azimuthal angle for any 71 and 5 because the only source of diffuse radiation in this case is the reflection from the melt pond bottom in accordance with eq. (7). inserting a delta-function for the phase function into the right side of eq. (2), integrating over q' and 4' and dividing by (1 aw), we reduce the transfer equation for the diffuse radiation t o the dif ferential form of beer's law: where t = (1 aw)r. (9) in terms of t, boundary condition (7) is expressed as xi? (t,)= a; 2n i " ~ ~ , r l ' ) r l ' d r l ' + f ~ , ~ ( $ ) ) , (10) ( i : where the optical thickness of the water layer i; is equal to k,lhwl. according to eq. (8) and boundary condition ( 6 ) , the diffuse radiance 1 7 ( t,) is decreased by a factor exp(-:) along the direction ( q , $ ~ ) between the pond bottom and top of the water layer. it is then reduced by a factor r(q) at the air-water interface and, finally, by another factor exp( -:) along the direction (-q,$) before reaching the pond bottom again. 2tw inserting i (t,)r($)exp( -7) into the right rl side of eq. (10) and integrating over q', the solution to eq. (8) is written as follows a;(l r(p,,))foexp(-f -7 tw vo rl i t ( 2 , v ) = n( 1 2c~ir3(22,)) and where is a generalisation for the third exponential inte gral (abramowitz & stegun 1964) integrating (1 r(q)it(o,q)q over the upper hemisphere yields f (0), the upwelling irradiance just above the air-water interface. dividing ft (0) derived from eq. (11) by fo and adding the fresnel reflection coefficient for the air-water interface, we obtain an expression for a, the spectral albedo for the melt pond of optical thick ness 't, under direct illumination for the case of a 46 a . p. makshtas & i . a . podgorny lambertian bottom: as earlier, ,lq a n d qo a r e related by e q . ( 1 ) . parameterisation of the function r3(t) t h e goal of this section is t o parameterise the function r3(t) so that % can be computed efficiently. because melt ponds a r e unlikely t o b e deeper than 1 m in the arctic, actual values of ‘t, a r e unlikely t o exceed 1 in t h e visible spectrum according t o data on k~ compilated by smith & baker (1981). consequently, the following series expansion can b e used for calculating e3(t): (-1)”t” m i 2 where c is t h e euler constant. a convenient where denotes t h e cosine of the critical angle for total internal reflection. expanding exp (-:) in a power series, we get 5 e3(t) r,(t) = (-l)mrmtn’, (19) i11 = 0 where rm is given by when eqs. (16) and (19) a r e employed to cal culate e3(t) o r e3(t) r3(t), the summation over index m is performed from 0 to a finite numbe1 m. finally, let us evaluate r3(0) which is a pre requisite for calculating radiometric quantities for an optically thin melt pond. i t is seen from e q . (14) that e,(o) = 0.5. according t o e q . (13), 2 r 4 0 ) is equal to the internal reflectance of radi ation at the air-water interface for radiation inci dent from below r + , for the case of a uniform radiance distribution at a plane water surface (preisendorfer 1976). t h e r + values are in the range from 0.47 to 0.49 for the visible spectrum (preisendorfer 1976). consequently, the value of r3(0) is about half t h e value of e3(0). monte carlo simulations monte carlo method was employed t o find an “exact” solution to eq. (2) with the boundary conditions given by eqs. (6) and (7). comparison of t h e monte carlo solution t o e q . (2) and the analytical solution to e q . (8) enables us t o esti mate errors of the analytical solution. these errors arise d u e to scattering of radiation in the water layer. t h e estimated errors give a measure of the precision of e q . (15) in calculating the pond albedo over the wavelength region of interest. t h e method t o b e applied in monte carlo siinu lations is similar t o t h e methods reported earlier in t h e context of computing underwater light fields (see mobley 1994 for references). in particular, a weight wo is assigned to each photon as follows wo = exp(-k,l) r(%). (21) h e r e gw is the path length of the photon, k is the number of fresnel reflections from the water air interface, and r ( q k ) is t h e fresnel reflection coefficient for radiation incident from below the interface. two detectors are used: the first to determine the upwelling irradiance f t (0) just above the water surface, and the second to deter mine t h e downwelling irradiance f .1 ( tw) just above the pond bottom. t h e one-dimensional ( t h e coordinate t) path of each photon is followed until t h e photon strikes t h e bottom twice. t h e coordinate q is used explicitly t o determine t h e direction of t h e photon travel. in turn, the coor dinate q5 is employed implicitly to compute a new value of q in accordance with eqs. (3) and (4) when a scattering interaction takes place. g o r d o n & brown (1974) introduced a modi fication of the monte carlo method to assess the influence of bottom albedo o n the diffuse k k = l calculation of melt pond albedos on arctic sea ice 47 reflectance of a plane-parallel ocean as a function of bottom depth and albedo. as this problem is very close to that addressed here, the method of gordon & brown (1974) is applicable to our study. in particular, an expression for the upwell ing irradiance measured by the first detector (above the water surface) is written as where f o t (0) is the contribution to ft (0) from photons that do not strike the bottom, f1 (0) is the contribution to f (0) from photons that strike the bottom once for a; = 1, and p is the ratio of the contribution to fl(z,) from photons that strike the bottom twice to the contribution from photons striking the bottom once for nl = 1. so, the value a, = 1 is applied to both contributions which form the ratio p, but the actual value of a; is then used to determine ft (0) from eq. (22). the important thing to mention is that the factor (1 a,p)-' in eq. ( 2 2 ) accounts for all the mul tiple reflections. the computations were carried out for the case of rayleigh scattering. accordingly, the phase function was specified by 3 4 x( y) = -( 1 + cosq y ) ) . (231 although the a, values for the clearest water do not exceed 0.31 in the 40g700 nm wavelength region (smith & baker 1981), our calculations were made for an overestimated value of a, = 0.5. moreover, the maximum possible value for the spectral albedo of melting white ice, ai = 0.8 (grenfell & maykut 1977), was used. thus, the effect of scattering on the pond albedo may be slightly overestimated. the maximum relative statistical error in estimating a,,, by the monte carlo method was about 1.5%. shown in fig. 2 are the a; values versus tw calculated for a solar zenith angle of 60". curve i (dashed line) represents the "exact" monte carlo solution. curves i1 and 111 represent albedos cal culated for the non-scattering water layer, i.e. either directly from eq. (15) (solid line) or using parameterisations (16) and (19) with m = 4 (dot ted line). z, is determined from z, using eq. (9). as seen from fig. 2, scattering has no effect on a; whenever t, < 1. beyond the visible spectrum tw can exceed 1 for actual ponds, but a, is neg ligible for wavelengths exceeding 700 nm. eq. 0.01 0.1 1 10 optical thickness fig. 2 . melt-pond albedo versus optical thickness of the water layer calculated using ( i ) the monte carlo method, (11) ana lytical expression (15), and (111) calculations using analytical expression (15) where functions e, (t) and r, (t) are computcd using expressions (16) and (19). (15) and, thus, parameterisations (16) and (19) (m = 4) are used below to cohpute a;. 0 bservations measurements in the barents sea the observational data presented in this study were collected during the r/v lance cruise in the northern part of the barents sea in august 1993 under the russian-norwegian oceanographic programme (rusnop). measurements of pond albedo were carried out on 12 august 1993 over a small multiyear floe with a diameter of about 150 m located near 78.8"n, 34.8"e. measure ments were also made of the albedo of the melting bare ice. the ice thickness was approximately 2 m. glitter patterns on the pond surfaces were not observed. wind speed was about 2 m/s. a quantum sensor li-190 sb with a spectral window of 40g700 nm was employed to measure both the incident and reflected irradiances over a sequence of melt ponds of varying depths. the sensor was located about 0.2 m above the water surface and between 1.5 and 2.0 m away from the bare ice to avoid reflected radiance from outside the melt pond surface. 48 a . p . makshtus & i . a . podgorny all albedo measurements were made under clear skies at about 1200 solar time. the solar zenith angle was about 60" and the full solar disc was visible. weather and illumination conditions were stable during the observations. measure ments of upwelling and downwelling irradiances for each individual pond were made between three and five times in order to estimate mean values and standard deviations of albedo. more over, before measurements were made, every melt pond was tested visually for the presence of bottom contamination, and only uncontaminated, clean ponds were selected. no clean ponds were found with a depth exceeding 0.35m; one ref erence measurement was made for a com paratively deep (0.5 m) contaminated pond. as seen from table 1, the measured albedo at h, = 0.5 m is as low as 0.35 compared to 0.59 observed at h, = 0.35 m. this is clearly connec ted, in our opinion, with cryoconite holes (eicken et al. 1994) that were observed on the bottom of the deepest pond. according to eicken et al. (1994), the occurrence of cryoconite holes is a consequence of contaminants deposited o n the pond bottom and is linked, therefore, to a decreased value of pond albedo. at the same time, the albedos reported in table 1 for the shallow (h, < 0.35 m) ponds are nearly inde pendent of pond depth. comparison with other duta sets these albedos are in reasonable agreement with observations made by other investigators. in par ticular, ivanov & alexandrov (1994) carried out measurements north of franz josef land during an expedition aboard r/v polarstern in august 1993 and found spectrally-averaged albedos of clean ponds to be 0.30 ? 0.05 for depths less than 0.3 m, and 0.26 ? 0.03 for depths in the range of 0.30 t o 0.50 m. although these albedo values are lower than those shown in table 1 for the shallow ponds, the difference can be partly attributed to employing the model pp-1 pyranometer which has a spectral window of 390-780nm, for the measurements performed by ivanov & alex androv (1994). morassutti & ledrew (1995) calculated regression curves for pond albedo in the 400 700 nm wavelength band versus pond depth based on an analysis of several hundred field measure ments. the regression curve, reported for the case of clear sky, demonstrates a sharp decrease in a depth range from 0 to 0.1 m but is almost constant at larger depths. spectrally-averaged albedo of melt ponds we used a simplified approach to compute the incident irradiance reaching the surface. because the atmosphere was assumed to be cloudless and aerosol-free, only the absorption of solar radi ation by o3 was taken into account. absorption by water vapor and other gases was ignored because their effect on solar radiation is insig nificant over the spectral region of interest (e.g. liou 1992). furthermore, rayleigh scattering in the atmosphere was also ignored. first, the direct incident irradiance reaching the surface exceeds the downwelling diffuse irradiance by an order of magnitude for the solar zenith angle of 60". second, the fresnel external reflectance for the case of uniform radiance at a plane water surface is about 0.066 (preisendorfer 1976) and is close to the observed value of r(kj of about 0.060 for e,, = 600. table 1 . albedo of melt ponds in the 4 w 7 0 0 nm wavelength band versus pond depth pond depth (m) melt pond bottom (top surface of the bare ice) albedo standard deviation bare ice 0.02 0.10 0.19 0.35 0.50 clean clean clean clean clean contaminated 0.84 0.54 0.53 0.56 0.59 0.35 0.05 0.02 0.01 0.02 0.02 0.02 calculation of melt pond albedos on arctic sea ice 49 the measurements of spectral albedo reported by grenfell & maykut (1977) for melting mul tiyear white ice were used to specify a;. absorp tion of solar radiation by o3 in the chappuis band for the total ozone content equivalent to 0.5 cm was calculated according to nicolet (1981). the k, values were taken from smith & baker (1981). spectrally averaged broadband albedo, ( g), for a spectral region (a1,&) is introduced as fol lows where fo(a) is the distribution of the incident spectral irradiance. the integration was performed from dl = 400 nm to a, = 700 nm with a step of 10 nm. 00 = 60” was used. the zero value of h, corresponds to both bare ice and ponds of infinitesimally small depth, hereafter referred to as “newly formed” melt ponds. the calculated (a,,,) are plotted in fig. 3 together with the measurements reported in table 1. discussion although the differences between calculated and observed albedos are significant, two conclusions can still be drawn from fig. 3. the first conclusion is that a step-decrease in albedo is likely t o occur when a melt pond forms. in order to address this issue in more detail, we write eq. (15) for t, = 0. clearly, this is the case of the newly formed melt pond. taking into account that 2r3(0) = r+ for the case of a lambertian bottom, we obtain from eq. (15) eq. (25) allows us to determine aml, the dif ference between ~ ( 0 ) and q, 0.0 0.2 0.4 0.6 0.8 1.0 pond depth (m) fig. 3. measured and calculated albedos for melt ponds and bare ice in the. -700 nm wavelength band. vertical bars represent standard deviations. as seen from eq. (26), aa; is negative if a;r+ > r ( h ) . this is satisfied for actual values of a; and 0,. the maximum absolute value of a % is about 0.12 for q = 0.6 and 0, = 60”. according to mullen & warren (1988), who calculated the spectral albedo of lake ice, the external surface reflectance tends to increase albedo over what it would be without the surface layer (air-ice interface, in our case), whereas the internal reflection directs radiation back down tending t o decrease albedo. with respect t o the problem addressed in this paper, one may con clude that the spectral albedo of the ice layer beneath the pondis larger than the spectral albedo of the bare ice with the same optical properties under conditions where the solar zenith angle is not too large. on the other hand, an analysis of table 1 of this study and fig. b8a from morassutti & ledrew (1995) suggests that there exists a difference between the albedos of newly formed pond and bare ice; the magnitude of this difference is about 0.1-0.3 in the 400-700 nm wavelength band. moreover, a similar sharp decfease in spectral albedo was reported. by perovich (1994) for a shallow (0.03m) melt pond. finally, this dif ference is also observed in our calculations of melt pond albedo reported in fig. 3. thus, the only way to explain both observed and modelled 50 a . p . makshtas & i . a . podgorny step-decreases in albedo is to postulate that the changes in structural and optical properties of the bottom, which occur when the melt pond forms, cause a greater decrease than predicted by eq. to assess the influence of the assumption that the melt pond bottom is a lambertian reflector, the case where this assumption is relaxed is exam ined. a convenient way to parameterise the upwelling radiance for the newly formed pond is to use the cardioidal radiance distribution (26). where e is a parameter. lambertian reflectance is the special case of e = 0. under the assumption that the law of diffuse reflectance for the pond bottom is independent of the direction of the incident radiation, eq. (25) is still valid for the radiance distribution given by eq. (27). this can be shown by applying eq. (22) to the newly formed pond. when q = 1 and absorption of the radiation in the water layer is negligible, the average contribution t o the upwelling radiance just above the air-water interface from photons that do not strike the bottom is exactly r ( h ) , while the contribution from photons striking the bottomonceis(1 r ( h ) ) ( l r+).furthermore, the ratio of the contribution to the downwelling irradiance at the pond bottom from photons that strike the bottom twice to the contribution from photons striking the bottom once is r + for the case of a; = 1. incorporating p = rr and the above considerations into eq. (22) yields eq. (25). in accordance with eq. (271, r + calculated for negative (positive) e is larger (smaller) than r + calculated for the case of a lambertian bottom. when e > 0, radiation is redirected into a more nearly normal direction and it is easier, therefore, for it to escape from the melt pond due to the reduced fresnel reflection at the small zenith angles. alternatively, for e < 0, radiation is more likely to be reflected back to the bottom. thus, deviations from lambertian behaviour can cause either an increase or reduction of a q . a negative e has a stronger effect on the absolute value of a&. for example, when e = -0.9 (which is representative for the upwelling radiance dis tribution observed in the upper ocean), and a; = 0.8, ~ ( 0 ) = 0.57 because r+ would be about 0.7 (preisendorfer & mobley 1985). the reference value of k ( 0 ) for e = 0 is as large as 0.7 as mentioned above, wind speeds during our observations were too small ( 2 m/s) to produce capillary wave slopes sufficient to cause a signifi cant effect on the penetration of radiation into the melt pond. the effect of capillary waves can be stronger, however, when a high wind speed is combined with a comparatively large (>60") solar zenith angle. the major contribution to the albedo change in this case would be due to the reduced fresnel reflection of the incident radiation, whereas the effect of capillary waves on the internal reflection would be smaller accord ing to preisendorfer & mobley (1985), therefore, with respect to the melt pond albedo, possible deviations from lambertan behavior of the pond bottom seem to be more important than the effect of capillary waves. the step-decrease in albedo is associated with a variation in f (tw), the downwelling irradiance entering the ice layer. for the case of direct illumination, contribution t o f 4 (t,,,) from the diffuse radiation field can be found by integrating i l ( t w , q ) q (see eq. (12)) over the lower hemi sphere. the contribution from the direct radiation fieldis f&(tw) (see eq. ( 5 ) ) . as a result, we have where denotes spectral transmissivity of the water layer, it can be shown using eqs. (15) and (29) that spectral albedo of the newly formed pond and its spectral transmissivity are related by the expression thus, tw(0) > 1 if a q < 0. the second conclusion from fig. 3 is that the melt pond albedo depends more on the optical properties of the bottom than on pond depth. to evaluate the effect of absorption of the short wave radiation in the water on pond albedo, let us determine the spectral radiative energy flux into the water layer (h,,,). the upwelling irradiance at the ice-water interface can be found calculation of melt p o n d albedos on arctic sea ice 51 table 2. spectral albedo of a melt pond, spectral transmissivity of the water layer and spectral radiative energy fluxes into the water and ice layers at a = so0 nm as functions of pond depth (a, = 0.8) pond dcpth (m) n, t, h,/fo h,/fo 0.0 0.70 1.51 0 0.30 0.1 0.69 1.49 0.01 0.30 1 .o 0.62 1.36 0.11 0.27 by multiplying eq. (28) by a;: ft(t,) = a;t,(t,)fo. (31) the difference between f ( t,) and f t ( t,) is the special radiative energy flux into the ice layer: h, = (1 dtw(%)fo. ( 3 2 ) finally, h, can be obtained by subtracting hi from (1 q ) f o : h, = (1 a;, (1 a ; ) ~ ~ ( t ~ ) ) ~ ~ . ( 3 3 ) table 2 shows the spectral melt pond albedos, spectral transmissivities of the water layer and spectral radiative energy fluxes into the ice and water layers computed for three different values of h, using eqs. (15), (29), ( 3 2 ) and ( 3 3 ) . these values represent a newly formed pond, a shallow pond and a deep pond respectively. calculations are performed for a = 500 nm and a; = 0.8. for convenience, the radiative fluxes are presented relative to fo so that knowledge of the absolute value of fo is unnecessary. the results reported in table 2 enable us to evaluate the effect of absorption of short-wave radiation in the water layer on the melt pond albedo. the effect is negligible for shallow ponds, and should be taken into account only for deep ponds. nevertheless, the usually observed dif ference between spectral albedos of melting bare ice (as high as 0.8 at a = 500 nm for the white ice) and deep ponds (as low as 0.2-0.3 at a = 500 nm for the old ponds) (e.g. grenfell & maykut 1977) is unlikely to be explained only by absorption of the radiation in the water layer which is rather transparent to the radiation in the visible spectrum. the major contribution to this dif ference should be attributed to the optical and structural properties of t h e underlying ice. conclusions in this study, we have both empirically and theor etically examined melt pond albedos in the 4 0 g 700 nm wavelength band as a function of the pond depth. an analytical approximation of spectral albedo was derived for a pond with a lambertian bottom, assuming that rayleigh scattering in the water is small compared to absorption. using a monte carlo method, it was shown that scattering in the water can be ignored. measurements of albedo in clean ponds were made in the barents sea in august 1993 under clear sky conditions. comparison of observations and theoretical calculations indicates that (1) a step-decrease in albedo is likely to occur when a melt pond initially forms, and (2) melt pond albedos depend more on the structural and optical properties of the underlying ice than on pond depth. the effect of absorption of short-wave radiation in the water on melt pond albedos needs to be taken into account for the deep ponds only. the analytical approximation to the melt pond spectral albedo can be inverted and applied to estimating the spectral albedo of melt pond bot toms as described by podgorny (1995). this enables us to determine the redistribution of solar energy between the melt pond and underlying ice from measurements of pond albedo and depth using the forward model developed in this paper. acknowkdgernenu. ~ the authors wish to acknowledge t. vinje for the organisation of the expedition aboard riv lance and j . h ~ k e d a l for his assistance in performing measurements of melt pond albedo. we are also grateful to t. grenfell, b . ivanov, d. perovich and g. shved for many suggestions and discussions and t o two anonymous reviewers for valuable com ments on this paper. assistance of m. berge and t. grenfell in preparing the manuscript for publication is highly appreci ated. this research was partly supported by the russian fund of fundamental research under grant 95-0.5-15315, by the inter national science foundation under grant nsfooo and by the joint institute for the study of the atmosphere and ocean contribution 339. references abramowitz, m. & stegun, i . a . (eds.) 1964: handbook of mathematical functions with formulas, graphs and math ematical tables. national bureau of standards, applied mathematics scries ss. barry, r. g . , serreze, m. c . , maslanik, j . a. & preller, r. h. 1993: the arctic sea ice-climate system: observations and modelling. rev. geophys. 31, 397-422. ebert, e. e. &curry, j . a. 1993: an intermediate one-dimen sional thermodynamic sea ice model for investigation ice 52 a. p. makshtas & i . a. podgorny atmosphere interactions. j. geophys. res. 98 (cs), ' l o o 8 s 10109. ebert, e. e . , schramm, j . l. & curry, j. a . 1995: disposition of solar radiation in sea ice and the upper ocean. 1. geophys. res. 100 (cs), 15965-15975. eicken, h., alexandrov, v . , gradinger, r . , ilyin, g . , ivanov, b., luchetta, a , , martin, t., olsson, k . , reimnitz, e., pac, r . , poniz, p. & weissenberger, j . 1994: distribution, structure and hydrography of surface melt puddles. ber. polarforsch. 149, 7 3 7 6 . gordon, h. r . &brown, 0. b. 1974: influence of bottom depth and albedo on the diffuse reflectance of a flat homogeneous ocean. appl. opt. 13(9), 2153-2159. grenfell, t. c . & maykut, g . a. 1977: the optical properties of ice and snow in the arctic basin. j. glaciol. 18(80), 445 463. grenfell, t. c. & perovich, d . k. 1984: spectral albedos of sea ice and incident solar irradiance in the southern beaufort sea. .i. geophys. res. 89 ( c 3 ) , 3573-3580. ivanov, b. v . & alexandrov, v. 1994: albedo of the ice cover during late summer time and energy exchange process. ber. polarforsch. 149. 47-51. jin, z . , stamnes, k., weeks, w. f. & tsay, s . c. 1994: the effect of sea ice on the solar energy budget in the atmosphere sea ice-ocean system: a model study. j . geophys. res. 99(c12), 25281-25294. langleben, m. p. 1971: albedo of melting sea ice in the southern beaufort sea. j. glaciol. 10 (58). 101-104. liou, k. n. 1992: radiation and cloud processes in the atmos phere. oxford university press. 487 pp. maykut, g . a . 1986: the surface heat and mass balance. pp. 395-463 in untersteiner n. (ed.): the geophysics of sea ice. martinus nijhoff publ., dordrecht (nato as1 b146). maykut , g . a . & perovich, d . k. 1987: the role of short wave radiation in the summer decay of a sea ice tover. j. geophys. res. 92 ( c 7 ) , 7032-7044. mobley, c. d . 1994: light and water. radiative transfer in natural waters. academic press inc. 592 pp. morassutti, m. p. & ledrew, e. f. 1995: melt pond dataset for use in sea-ice and climate-related studies. ists-eol tr95-001, earth-observations lab., ists and dept. geog., university of waterloo, ontario, canada. 53 pp. moritz, r . e., curry, j. a , , thorndike, a. s. & untersteiner, n. (eds.) 1993: sheba. a research program on the surface heat budget of the arctic ocean. apl-uw, seattle. 33 pp. mullen, p. c . & warren, s . g . 1988: theory of optical proper ties of lake ice. j. geophys. res. 93 (d7), 840>8414. nazincev, ju. l. 1964: teplovoj balans poverchnosti morskogo ledjanogo pokrova v central'noj arktike (heat balance of the surface of the multiyear ice cover in the central arctic). aanii, trudy, 267, 11g-126. nicolet, m. 1981: the solar spectral irradiance and its action in the atmospheric photodissociation processes. planet. space sci. 29 ( 9 ) , 951-974. perovich, d. k. 1994: light reflection from sea ice during the onset of melt. j. geophys. res. 99 (cz), 3351-3359. podgorny, i. a . 1995: measurement of the optical charac teristics of a puddle. russian meteorology and hydrology, n3, 50-58. preisendorfer, r . w. 1976: hydrologic optics. vol. 6: surfaces. pacific marine environmental laboratory, erl-noaa, seattle. 390 pp. preisendorfer, r. w. & mobley, c. d . 1985: unpolarized irradiance reflectances and glitter patterns of random capil lary waves on lakes and seas, by monte carlo simutation. noaa tech. memo. e r l pmel-63, pacific marine environmental laboratory, erl-noaa, seattle. 141 pp. smith, r. c. 1973: optical properties of the arctic upper water. arcric 26 ( 4 ) . 303-313. smith, r . c. & baker, k. s . 1981: optical properties of the clearest natural waters (20cl-800 nm). appl. opt. 20 ( 2 ) . 177 184. notation the third exponential integral incident spectral irradiance (w m-* nm-i) downwelling spectral irradiance (w rn-' nm-i) upwelling spectral irradiance (w m-* nm-') thickness of the water layer or pond depth (m) spectral radiative energy flux into the ice layer (w m-2 nm-i) spectral radiative energy flux into the water layer (w nm-') diffuse spectral radiance (w m-* nm-i sterad-') diffuse downwelling radiance (w m-* nm-l sterad-') diffuse upwelling radiance (w m-z nm-' sterad-i) refractive index of the water internal reflectance of the air-water for uniformillumi nation fresnel reflection coefficient for irradiance incident on the air-water from above fresnel reflection coefficient for irradiance incident on the air-water from below fresnel reflection integral spectral transmissivity of the water layer for the downwelling irradiance weight assigned t o a photon phase function spectral albedo of the ice layer, ( f f ( z w ) / f i ( ~ ) spectral albedo of the melt pond spectral albedo of the newly formed pond spectrally averaged albedo of the melt pond scattering angle parameter of the cardioidal radiance distribution difference between a , ( o ) and lu, path length of photon in the water layer cosine of zenith angle in the water layer cosine of zenith angle for direct solar radiation in the water layer cosine of the critical angle for total internal reflection solar zenith angle (degrees) spectral absorption coefficient of the water (m-i) wavelength (nm) single-scattering albedo of the water cosine of zenith angle in the atmosphere cosine of the solar zenith angle scattering coefficient of the water (m-') optical depth optical thickness of the water layer (exact solution) optical thickness of the water layer (analytical solu tion) azimuthal angle (degrees) solar azimuthal angle (degrees) glaciomarine sedimentation in a modern fjord environment, spitsbergen anders elverhdi, 0 i v i n d l 0 n n e a n d reinert seland elverhoi, a , , l m n e , 0. & seland. r. 1983: glaciomarine sedimentation i n a modern fjord environment, spitsbergen. polar research 1 n.s., 127-149. by means of high resolution acoustic profiling and correlation of echo character and sediment lithology, fjords in western and northern spitsbergen are shown to be blanketed by a 5-20 m layer of acoustically transparent sediments consisting mainly of soft homogeneous mud with ice rafted clasts. acoustically semi-transparent material is found on slopes and sills reflecting their coarser composition. the areal average depositional rate in the outer fjord is in the range of from 0.1 to l.omm/year, increasing towards the glaciers. in kongsfjorden, 5&100mm/year of muddy sediments is deposited at a distance of lokm from the calving kongsvegen glacier. close to the ice front ( 4 . 5 km) coarser grained, interbedded (sanqmud) sediments are deposited. the main sediment sources are from settlement out of the turbid surface sediment plume, combined with various types of gravity flow (sediment creep, minor slides, and slumping). material deposited from turbidity current is probably of minor importance. on shallow sills the sediments are remobilized by icebergs. the sediment adjacent to the ice front is reworked and compacted during surges, a common form of glacial advance for spitsbergen glaciers. during the surge considerable amounts of coarse-grained sediment are deposited by meltwater in front of the ice margin. anders eluerhbi, norwegian polar research institute, p . 0. box 158, 1330 oslo lufthaun, norway; 0 i v i n d lbnne, norwegian petroleum directorate, p . 0. box 600, n-4001 stavanger. norway; reinert seland. elf aquitaine norge als, p . o . box 168. n-4001 stavanger, norway; april 1983 (revised july 1983). introduction in partly glaciated regions such as svalbard, alaska and arctic canada, sediment laden (1 5 $) meltwater streams result in high depo sitional rates in the fjords, 0.1-3 m/year (hoskin & burrell 1972; repp 1979; elverhei et al. 1980; molnia & hein 1982; gilbert 1982). additionally, sediment is supplied by iceberg calving from tidewater glaciers. these depo sitional rates, based mainly on bottom sediment samples, only relate to the areas adjacent to melt water outlets. knowledge of how a glacially fed fjord acts as a sediment trap is limited, however. from the few investigations available, the depo sitional rate seems to decrease exponentially away from the source (hoskin et al. 1978; syvitski & murray 1981; gilbert 1982; farrow et al. 1983). this study, in which kongsfjorden has received most attention, high resolution acoustic profiling and sediment sampling were undertaken to inves tigate the thickness and distribution of sedimen tary facies in fjords of spitsbergen (figs. 1 and 2). the objectives of the study were to identify: (1) sediment composition and depositional rates throughout the fjords, and (2) factors con trolling the sedimentation. surging is a common mode of advance for glaciers on svalbard (liest01 1969; schytt 1969). kongsvegen is the main glacier calving into kongsfjorden, and attained surge maxima in c. 1869 and in 1948 (fig. 3). a surge is also reported from one of the other investigated fjords, pau labreen, at the head of van mijenfjorden (rowan et al. 1982). this paper also comments on the sedimentary pattern from these surging tidewater glaciers. background glaciology at present about 60% of svalbard is covered by ice and a number of the glaciers terminate in the sea. generally, the glaciers on spitsbergen are retreating (liestd 1975), but most of them surge periodically, advancing between a few hundred metres and more than 10 km during a couple of months or years (liest01 1969). both polar and subpolar glaciers are present. most glaciers probably had their largest holo cene extent during the previous century, corre sponding to the uppermost trimline above the 128 anders eiiwrhoi, 0 i v i n d lqnne and reinert seland a l o c a t i o n nldp b fig. i . map showing the loca tion of 3.5 k h z echo-sounding profiles in fjords of western and northern spitsbergen. present glacier surface (liestsl 1969: liestsl pers. the investigated fjords: smeerenburgfjorden, comm ). a genera! glacial advance probably liefdefjorden, raudfjorden. and tributary fjords occurred between 3500 and 2000 years bp (barto isfjorden. in van mijenfjorden, part of the sill a n o w l i i 1977). is subaerial. in kongsfjorden, isfjorden, and woodfjorden. the fjord trough continues as a depression across the shelf without a major sill. kongsfjorden has an inner basin separated from the main basin by a shallow sill associated with the lovensyane (fig. 2). t h e fjord basins a r e generally 200 to 300 m d e e p . bnthjmetr\. the characteristic outer shallow sill commonly associated with fjords is present in only some of glaciomarine sedimentation in svalbard fiord 129 fig. 2 . bathymetric map of kongsfjorden showing boomer and 3.5 khz echo-sounding profiles and-localities for sedimcnt and water samples and light scatteringitransmission measurements. fig. 3 . positions of the kongsvegen ice front since 1869 (based on data from olav liestel). i i 130 anders elverhai, biuind l a m e and reinert seland x fig. 4. salinity and temperature ~ section across kongsfjorden. w for location, see fig. 2 . atlan tic water is seen to flow into the fjord at a water depth of about 75 m. measurements: 1/9.1981. 14 lillrl n 0 -\ '1 --yl temperature oc salixity "/oo physical oceanography the hydrographical conditions in the fjords have not been studied in detail. and knowledge of the winter conditions is particularly limited. long term measurements in the mouth of kongsfjorden reveal homogeneous cold, saline water through out the water column in late winter/early spring. this homogeneity is probably formed in response to cooling and convection during winter (blind heim & ljaen 1972). during spring and summer. atlantic water penetrates into kongsfjorden on the southern side at intermediate water depths (75-loom, fig. 3 ) . the mechanism driving this current is probably the outflow of meltwater which as a brackish surface plume is forced along the northern side of t h e fjord. but the current is also influenced by the coriolis force (gam melsrad pers. comm.). t h e influx of atlantic water into kongsfjorden is probably facilitated by t h e lack of an outer shallow sill. in kongsfjorden the 5-10 m thick summer sur face layer has a salinity of 31-32%0 and a tem perature of 2 to 4°c. investigations in fjords with sills (e.g. v a n mijenfjorden (schei et al. 1979), smeerenburgfjorden, and raudfjorden (gam m e l s r ~ d & rudels 1983)) show a better defined halocline near the surface. in van mijenfjorden s t a t i o n n r i . fig. 5 . distribution of sus pended matter in a section across kongsfjorden in terms of light transmission. sampled sediment concentrations in mgh at some localities (light transmission plotted as in% light transmission). for loca tion, see fig. 2 . measurements: 1/9, 1981. glaciornarine sedimentation in svalbard fiord 13 1 the surface salinities a r e relatively fresh at the fjord head, 5-20%0, gradually increasing to 32% down the fjord (schei et al. 1979). fjords with an outer shallow sill commonly have a cold, -1 to +0.5"c, bottom water mass during the summer season. suspended particulate matter during summer all the fjords are characterized by a turbid surface overflow, which can vary in volume and position in response t o meltwater/ sediment discharge, wind directions, and tidal currents. sediment concentrations in the plume adjacent to kongsvegen can reach 300-500 mg/l (elverhoi e t al. 1980), decreasing to 1-5mg/l in central and outer parts of the fjord (fig. 5). in the inner basin concentrations in intermediate water masses may reach 2 0 2 5 m d l and to 2 3 m d l in t h e central parts (fig. 5), while relative clear water in the outer parts of the fjord contains 0.5 mgh (station 20) (fig. 2). t h e concentration in the bottom of t h e nepheloid layer has been measured at 13 mgh (station 20). investigations of the suspended matter in the central and outer parts of smeerenburgfjorden and raudfjorden show a similar pattern (light scattering measure ments, g. kullenberg pers. comm.) data acquisition seismic equipment included an eg & g 100 j boomer uniboom and a 10 k w 3.5 khz penetra tion echo-sounder. t h e bandpass filter settings were 200-4000 hz and 3 . 2 4 . 4 khz, respectively. the vertical resolution of the boomer is about two metres. that of the 3.5 khz echo-sounder about o n e metre. profile locations are shown in figs. 1 and 2. sediment samples were obtained with a three metre long gravity corer, with an internal diameter of 110 mm (fig. 2). temperature and salinity were measured a t a number of stations in raudfjorden, smeeren burgfjorden, and kongsfjorden using a neil brown ctd-sonde. t h e distribution of sus pended particles was measured simultaneously by an in situ integrating light scattering meter (univ. copenhagen, jerlow 1961), o r a nephelometer/ transrnissiometer (montedewo-whitney, mark iv). a t some of the stations water samples were obtained by a rosette sampler with 2.5 liter nisken bottles (locations, fig. 2). the water samples were vacuum filtered on to preweighed 4 7 m m millipore filters of 0.4 pm pore-size. laboratory methods t h e sediment cores were split with an osmotic knife and x-radiographed. shear strengths were measured, when possible, by means of a falling cone penetrometer. sediment colour was deter mined using a munsell soil colour chart after the sediment was dried at 50°c to avoid the influ ence of monosulphides. grain size distribution (gravel, sand, mud), water content and bulk den sity were determined according to standard pro cedures. materials for i4c-dating were washed in distilled water before drying at 50°c. then sealed in a plastic bag, and analysed within two weeks. acoustic nomenclature classification of echo types t h e relationship between echo character (3.5 khz) and sediment lithology has been dis cussed at length by damuth (1975). damuth & hayes (1977), and damuth (1978,1980). bottom echoes a r e classified in relation to the degree of prolongation of the bottom echo return and acoustic transparency. prolonged echoes. t h e degree of prolongation of t h e bottom echo refers t o the duration of the reflected event compared to the emitted pulse. t h e subdivision is mainly in accordance with damuth (1978): distinct bottom echoes (include weakly pro longed bottom echoes) (fig. 6). semi-prolonged bottom echoes (fig. 6) prolonged bottom echoes (fig. 7) t h e same classification can also be applied to sub-bottom reflectors. acoustic transparency. t h e acoustic trans parency refers to the intensity of the grey tone o n the record in between reflectors (e.g king 1967). t h e degree of transparency is divided into the following classes: acoustically transparent: a weak grey tone is s e m i p r o l o n g e d a c o u s t i c a l l y b o t t o m e c h o e s i s e m i t r a n s p a r e n t d i s t i n c t 2 0 0 ~ 4 0 0 m s ~ _ _ _ _ 0 2 i i i l ki n fi g. 6 . in te rp re te d ac ou st ic p ro fi le o f k on gs fj or de n. in cl ud in g il lu st ra ti on s of o ri gi na l d at a fr om n ea rb y pr of il es . f or t he i nt er pr et ed p ro fi le a s ei sm ic v el oc ity o f 2 km /s ec i s ap pl ie d. c l o o m s . _ .. 0 1 2 k m in t e r b e d d e d p r o x im a l d e p o s it s / i i i d is t a l h o m o g e n e o u s m u d 5 0 m s 1 0 0 m 0 5 0 2 -2 1 0 0 y 3 % 1 5 0 ; 2 0 0 c i 5 0 v i fi g. 7 . i nt er pr et ed a co us ti c pr of ile o f th e in ne r ba si n in k on g5 fj or dc n in cl ud in g or ig in al d at a. ( b as ed o n a se ls m ic v cl oc ity u f 2 kr n' .w c. ) f or l oc at io n. s ee f ig 6. 134 anders elverhgi, biuind l ~ n n e and reinert seland present on the record (fig. 6). sub-bottom reflectors may be clearly identified. acoustically semi-transparent: a heavier grey tone is observed but sub-bottom reflectors may still be clearly identified (fig. 6). -acoustically opaque: a dark grey tone is probably represents bedrock because this reflec tor can be followed to the shore where bedrock is exposed. reliable data on unit i are confined to the inner basin. in the main basin the identi fication of this unit is more uncertain. observed and sub-bottom reflectors become diffuse or almost completely masked. the echo character is mapped in areas where the penetration exceeds three ms (two-way travel time). the degree of transparency where i t is affected by prolonged bottom echoes is not mapped. acoustic and sediment stratigraphy in kongsfjorden four acoustic units are identified. the lower units, i , 11. and 111. are mainly identified from the boomer records. the uppermost one, unit l v , was mapped by 3.5 khz penetration echo sounder. unit 1 bedrock(?) the upper surface of unit i is marked by a high amplitude seismic reflector (fig. 6). the unit unit i i compacted glacigenic deposits unit i1 is characterized by a paucity of distinct internal reflectors except for a few hyperbolae (figs. 6 and 7). in the inner basin, however, the unit can be subdivided into two units separated by a continuous reflector. in the main basin unit i1 is often seen t o form topographic highs. max imum thickness (170 ms two-way travel time) is observed in the central part of the inner basin. sediment cores into unit i1 show stiff sediments with a variable content of coarser material (figs. 8.9 and 10). the gravel content is typically higher than in the overlying soft mud (dropstone sedi ments). it is not possible yet to say whether unit i1 is a very coarse glaciomarine deposit which has been loaded subsequently by an ice advance, or whether it is primary till deposit. because of the high content of gravel, shear strength could not be measured. in the lower part of core 111 (fig. lo), from the same area, a shear strength of 10 kn/m' was recorded but this was in a different type of material, significantly less stiff than the fig. 8. triangular diagram showing the grain size compo sition of cores, based on aver age values for each lithological unit i n the core. classification based on holtedahl (in myhre 1974). glaciomarine sedimentation in svalbard fiord 135 unit iv 1 a a n i , , , , , i . , , i i i 1 . 5 2 . 0 2.5 bulk density legend: v glaciomarine deposits basin 0 glaciomarine deposits slopes and sills glaciomarine deposits -surge and icefront deposits a till fig. 9. bulk density and water content of the cores, based on average values for the lithological unit in the core. other samples. i n core 107 the material was par ticularly stiff, almost with a shale texture. unit i i i surge depositslice front deposits unit i11 is typically acoustically opaque to the 3.5 khz profiler, but diffuse parallel reflectors, hyperbolae, and discontinuous reflectors may be identified on boomer records (figs. 6 and 7). the unit is found in minor depressions in unit i1 and proximal to moraine ridges o r directly overlying unit i. these sediments, sandy gravelly mud, were recorded in the lower parts of the cores from the shallow sill south of lovcn0yane (core 105, 106). because these deposits occur just outside the maximum extent of the 1948 surge (and also the 1869 surge south of lovenoyane) they were prob ably brought to the ice front by the increased meltwater discharge during these surges (weert man 1969; thorarinsson 1969; liest01 1969). these sediments will later be referred t o as surge deposits. sediments of a similar composition as the surge deposits are also found closer to the modern ice front (station 110, fig. 2 ) . these sediments are interpreted as more local ice front deposits associ ated with the meltwater stream (see ice-proximal coarse-grained sediments by powell (in press)). general description. unit i v is a continuous cover of mainly transparent and semi-transparent sediments extending throughout the fjord (figs. 6 and 7 ) . internal reflectors are mostly found in the inner part of the main basin. in general, prolongation of the bottom echoes increases and the degree of acoustic transparency decreases towards the fjord head (fig. 11). maximum sedi ment thicknesses are found in the deeper parts of the main basin along the fjord axis, 30-40 ms (two-way travel time) (fig. 12). in the inner basin, the sediment thicknesses decrease towards the front of kongsvegen. near t h e ice front, unit i v is not identified o n the records because the soft sediment cover is less than 1-1.5 m. i.e. less than the resolution of t h e 3.5 khz signal. t h e colour of the sediments also varies down the fjord (fig. 10). i n the inner basin and central part of the main basin, light reddish brown sedi ments dominate, reflecting the old r e d devonian rocks in the source area. in the outer fjord and in kongsfjorddjupet the colour is greylgreyish brown. subdivision of unit iv. sediments which belong to unit i v are subdivided into: (a) mud with interbedded sandy layers (figs. 10 and 13), (b) homogeneous mud with a relative low content of sand and gravel clasts (figs. 10 and 13), (c) sandy gravelly mud on slopes and sills (figs. 8 and 9), and (d) mud o r sandy mud, sometimes finely lami nated (on x-radiographs), bioturbated mostly by polychaetous worms. high content of monosulphides (black colour, and release of h2s) (figs. 10 and 13). unit iva and b contain numerous monosulphid layers, 2-3 mm thick with a n interlayer distance of >lo cm (fig. 10). n o evidence of bioturbation is seen in these sediments. unit iva is only found underneath unit ivb, and these two latter units a r e only observed in the inner basin and on the sill south of lovenoyane. unit iva and ivb. t h e outer part of the inner basin is capped by a 5-10 ms thick acoustically transparenqsemi-transparent sequence. this sequence is divided into two subunits by a weak internal reflector (fig. 7 ) . correlation with the 136 anders elrierh@i, qiuind l o m e and reinert seland ; 827 t's h 5 h.. . . . : , , , . , . , . , . . . . , , , . . . , , , . , . . . , , ', , i , , ' . i y: el glaciomarine sedimentation in sualbard fiord 137 fig. 11. map of kongsfjorden showing the echo types. a. degree of acoustic trans parency. b . degree of prolon gation of the bottom echoes. note that echo types are only mapped for areas where sedi ment thickness exceeds 3 ms. acoust 1 c transparency -09 5 5 s e m i prolonged o 5 1'10 b -05 stratigraphy in cores 111 and 112 indicates that the upper subunit may consist of the soft homo geneous mud (figs. 10 and 13), while the lower subunit appears to correspond to the interbedded sediments. mode of deposition, unit iva, interbedded prox imal deposits. according to a previous inves tigation in the inner basin (elverh0i et al. 1980), layered sediments are confined to areas close to the ice front, <500m. similar sediments have also been described in front of calving tidewater glaciers where the layers are interpreted as having been formed in response to a varying meltwater/sediment discharge of the underflow or from reworking of the primary sediments by gravity flow (mackiewicz & powell 1982; powell in press). in kongsfjorden, the meltwater enters the fjord at sea level. current velocity of the surface plume may exceed 50cm/sec, and medium-grained sand is observed 200m away from the ice front in the surface plume (elverhd et al. 1980). both the discharge and direction of the surface sediment plume may vary considerably over short periods (days/weeks). we therefore suggest that these sediments are formed in response to such variations in the meltwater/sediment discharge of 138 anders elverhoi, @ b i n d linne and reinert seland 1'10 19 t h i c k n e s i n two-way t r a v e l t i m e of unit a a 0 3 ms 3-5 '1 5 1 0 8 0: 1 0 2 0 2 0 3 0 01 > 3 0 18 u n c e r t a i n c o n t o u r s t u d y a r e a -- fig. 1 2 . isopach map of unit iv. acousticall) transparent and semi-transparent sediments in kongsfjorden the surface sediment plume, and not by under flow. this view is reinforced by considerations of the local bathymetry, which would require an underflow current to flow uphill across hummocky terrain (fig. 7 ) . mode of deposition, unit ivb, distal homogeneous mud. generally, the surface sediment plume flows out of the inner basin through the northern outlet and may also extend through the southern outlet. sediment settling from these surface sedi ment plumes is probably the main source of the fine-grained glaciomarine mud (hoskin et al. 1978; elverhcbi et all980; syvitski &murray 1981; gilbert 1982; farrow et al. 1983). the relatively low content of ice rafted materials is in part related to the high depositional rate of mud (elverhfli et al. 1980). it may also be due to the fact that icebergs calving off from the kongsvegen glacier pass through the area relatively rapidly. the observed semi-regular pattern of mono sulphide layering has been discussed previously ( e l v e r h ~ i et al. 1980), and attributed to organic material derived mainly from spring diatom blooms. similar layers have also been found in fjords in alaska, also interpreted as annual markers (hoskin & burrell 1972; powellin press). unit ivc, slope deposits. the sediments on the slopes and sills are generally almost acoustically opaque or semi-transparent with prolonged/ semi-prolonged bottom echoes (fig. 6). corre lation with sediment lithology shows that these slope deposits consist mainly of sandy, gravelly mud (fig. 14). on the shallow sill south of lovencbyane bedded sediments were cored, probably formed in association with the overturning of numerous grounded icebergs (ovenshine 1970). ice goug ing, observed by side scan sonar (wiseman pers. comm.) suggests that the sediments on the sill are subject to reworking. unit ivd basin deposits. in the main basin and in kongsfjorddjupet sediments are acoustically transparent with distinct bottom echoes (fig. 6). correlation with sediment lithology shows that these deposits consist of soft mud with a relatively low content of coarser materials (fig. 14). tex turally these basin deposits differ only slightly glaciomarine sedimentation in sualbard fiord 139 fig. 13. x-radiographs of two cores from kongsfjorden. ( a ) core 112, from the inner basin. showing the transition from interbedded proximal sediments into the overlying homo geneous distal mud with dropstones. (b) core 121. from kongsfjorddjupet, illustrating the basin deposits. the 'threads' show bioturbation, mainly from polycheats. note the diffuse lamination between 0.6 and 0.7 m depth. 140 anders e l u e r h ~ i , 0 i v i n d l0nne and reinert seland fig. 14. plot of the echo types in relation to grain size com position. grain size classitica tion based on holtedahl (in sand myhre 1974). comments on the fjord-bed morphology in the inner basin t h e northern front of kongsvegen, which does not surge ( l i e s t d pers. comm.), advances 30 50 m during t h e winter and retreats 50-100 m in from the homogeneous distal mud in the inner basin (fig. 10). t h e term basin deposits is applied to distinguish these sediments from those in the inner basin where the depositional rate is much higher (discussed later). glaciomarine sedimentation in svalbard fiord 141 ‘ 3 0 0 1 0 km fig. 15. interpreted acoustic profiles of dicksonfjorden and isfjorden. a seismic velocity of 2 km/zec is applied. the summer by calving. the hummocky relief in the inner basin of kongsfjorden (fig. 7) is believed to have formed in response to these annual oscillations of the ice front. acoustic surveys in the isfjorden area, raudfjorden, smeerenburgfjorden, and liefdefjorden/woodfjorden in general the sea floor is blanketed by acousti cally transparent sediments with distinct bottom s e l i e f d e f j o r d e n r 0 01 fig. 16. interpreted acoustic profiles from liefdefjorded woodfjorden and smeerenburgfjorden. a seismic velocity of 2 k w s e c is applied. echoes (figs. 15,16 and 17). one or two sub bottom reflectors parallel with the seabed are always present in the basin and may also be traced across minor sills and up slopes. sediments are thickest in the basin, thinning towards slopes and ridges. based on the relationship of lithology and echo types (fig. 14), this sediment drape is inter preted as a mud or sandy mud with a relatively low content of coarser grained sediments. for the inner parts of isfjorden the acoustic stratigraphy can be related to a ten metre long core (fig. 18). the lowermost reflector in the area was probably not sampled by the core. with reference to the sediment stratigraphy in kongsfjorden, the upper six metres are homo geneous distal mud/basin mud, underlain by interbedded proximal deposits, while the two low ermost lithological units may be ice front deposits. vema 2 3 6 5 ne 3 5 0 m s -400ms 4 5 0 m s 1 0 4 km i i i fig. 1 7 . 3.5 khz echo-sounding profile from the inner part of isfjorden. for location. see fig, 15. 142 anders eluerhsi. o i v i n d lonne and reinert seland . . . fix. i 8 sedimeni drscripiion of the l'esia-core % h i from the inner part of laflorden for location. see fig. 1. the ittho facies of the different u n i t s are also indicated (description ha$ed on megascopic description of split core. lamont-doherr! geo logical obsenator! of colurnbla l'niverait) , 1976). w in adventfjorden a minor sill is present in the central part of the fjord. inside this sill an acoust ically layered sequence is present (fig. 19). t h e r e is a delta at the head of adventfjorden and the layered sediments may correspond to prodelta ice deposits. according to the profile. delta sedi ments are trapped inside the sill. a similar phenomenon of delta sediments to be trapped inside the sill of another tributary fjord is also seen i n the outer part of g r ~ n f j o r d e n . acoustic survey in van mijenfjorden the fjord is divided naturally into an outer and an inner basin separated by a sill (the central sill) (fig. 20). the outer basin acoustically transparent sediments with distinct bottom echoes, i.e. soft mud o r sandy mud, are found in the outer basin (fig. 21a). four t o six internal reflectors parallel to the seabed are pres ent. the thickness of the unit decreases towards the o u t e r and central sill from a maximum of about 20 m . a n underlying acoustically opaque unit with prolonged bottom echoes, indicating coarser-grained sediment, occurs in some places. e 1 o o m s 0 z k m 2 0 0 m s ~~~ f i r 1') 3 5 k l l z echo-sounding profile from ad\enlflordcn. for location. see fip 1 0 00 i i 1 0 km 0 akselsundet till-surf a c e 0 ti rt 3 5. 1 0 0 3 i i i l o c a t i o n map d e p t h i n m 1 6 ' i id 3 fig. 20. interpreted acoustic profile from van mijenfjorden. a seismic velocity of 2 km/sec is applied w e -150ms i 200ms 0 2km c e n t r a l slll maximum e x t e n t of l a t e holocene c ' i r g e w a c o u s t i c a l l y e s e d i m e n t s t l l l s u r f a c e --50ms b e d r o c k ? 1 5 0 m s 0 4 km fig. 21. 3 . 5 khz echo-sounding profiles from van mijenfjorden. for location see fig. 20 144 anders elverhli, oiuind l l n n e and reinert seland the inner basin in the inner basin, topography is hummocky and has amplitudes ranging from 2-3 m to 10 m and wave lengths between 100 and 200m (fig. 21b). close to the central sill there is an abrupt change in bottom relief, with an even surface sloping gently down towards the sill. maximum observed sediment thickness, 60 ms (two-way travel time), is observed close to the central sill. the sediment thickness decreases towards the mouth of rin dersbukta. a number of acoustical units can be seen. but no core control is available. the acoustic stratigraphy is tentatively interpreted using the holocene glacial history of the area. ( a boomer and sampling survey is planned for this area.) paulabreen surged between 600 and 250 years ago, covering considerable parts of the inner basin (haga 1978; rowan et al. 1982), and the base of the uppermost and acoustically transparent unit is interpreted as a till surface. the change in relief to the central sill is likely to define the maximum extent of the glacier surge. the sediment between the maximum ice front position and the sill may consist of deposits built up during the surge (or previous surges). the thin, uppermost and acoustically transparent unit is suggested t o con sist of sediments deposited after the glacial retreat, > 9 0 years ago. at the time the glacier front was located inside the mouth of rinders bukta (liest01 pers. comm.). from terrestrial investigations the maximum late holocene glacial extent has been placed at conwentodden (fig. 20) (rowan et al. 1982). the fact that the acoustically transparent upper unit forms a layer of uniform thickness throughout theinner basin suggests ice extended t o the central sill. sedimentation rates kongsfjorden inner basin assuming that the monosulphide layers are annual markers, an average sedimentation rate of 50-100 mm/year is estimated for the inner basin ( e l v e r h ~ i et al. 1980). these values seem to be confirmed by the observed thicknesses of the gla ciomarine deposits (unit iv, i.e. homogeneous distal mud and interbedded proximal deposits) above the till. at a locality covered by ice until about 20 years ago (core 109) (figs. 2 and 3), the till was encountered at a depth of 1.35m, indi cating an average sedimentation rate of 70mm/ year. just inside the 1948 moraine the till was covered by 2.20 m of sediments, i.e. an average sedimentation rate of 80 mm/year. outside the 1940 moraine the thickness of the glaciomarine sediments above the suggested till surface is 10 ms (two-way travel time) adjacent to the 1869 ice front position, decreasing to 8 m s towards the 1948 moraine. applying a seismic velocity of 1500 m/sec for these glaciomarine sediments, their thickness is 6-8m in the area in between the 1869 and 1948 ice front position. assuming deglaciation 100 years ago (fig. 3), a sedimen tation rate of 60-80 mm/year is implied. the inner basin is about 15 km2, which in turn indicates that about 2.106 tons are deposited annually (bulk density: 1.7 g/cm3). kongsfjorddjupet in core 121, located in the central part of kongsfjorddjupet, gastropods (epitonium grsnlandicum) are dated (table 1). the dated sample consisted of seven specimens distributed over 10cm. the age of 1730 & 140 years bp at a sediment depth of 70 cm (75-65 cm) shows an average sedimentation rate of 0.4 mm/year. van mijenfjorden inner basin paulabreen surged between 600 and 250 years bp (rowan et al. 1982). the thickness of the gla ciomarine sediments above the suggested till sur face is about 1.5-3m. assuming the area to be deglaciated 200 years ago, the sedimentation rate has been 15 mm/year. discussion sediment distribution and sources in general there is a basinward thickening and fining of the mapped sediments. several processes are believed to have governed the sediment dis tribution (fig. 23). sediment settling from the turbid surface flow is probably the main sediment source for fine grained deposits in glacial fjords (hoskin & bur re11 1972; hoskin et al. 1978; syvitski and murray 1981; gilbert 1982; farrow et al. 1983). however, the distribution of the overflow and sediment thickness maxima may not coincide, except close glaciomarine sedimentation in svalbard fjord 145 om 100 p l i l : l 2 0 0 fig. 22. interpreted profile from outside blomstrandbreen in kongsfjorden showing probable fan deposits. for location, see fig. 2. to the meltwater outlets. turbidities and related gravity flow deposits have been reported from glacial fjords (holtedahll975; gilbert 1982; pow ell in press). sedimentary structures used to infer these processes have not so far been observed in the kongsfjorden sediments. even where con siderable polychaete activity is seen (fig. 13), very fine laminae have remained intact. the homogeneous structure in the other cores from the main basin is thus considered to be primary. however, transport by gravity flow is demon strated by a fan-like feature outside blomstrand breen (fig. 22) and probably slide deposits are seen outside dicksonfjorden (fig. 15). fjord deltas at the mouth of meltwater rivers are common features along the fjords. detailed investigations of their morphology by means of side scan sonar have been carried out on the delta slope at the head of adventfjorden, showing sub marine chutes on the upper delta slope (prior et al. 1981). as shown from the 3.5 khz echo-sound ing profiles, the delta sediments are trapped by a sill. however, without a sill, the sediments are likely to continue into the main fjord. chute and slump features are also observed in the inner part of kongsfjorden near the ice front (wiseman pers. comm.). near the meltwater outlet in kongsfjorden, and on the slopes of the sill south of loveneyane, side scan sonar records show evidence of sediment creep (wiseman pers. comm.). sediment move ment as creep is due to the action of gravity on extremely underconsolidated sediments, and may operate on slopes as low as one per cent (kraft et al. 1979). the above observations on chute, slumping and sediment creep have so far been made in a few areas only. similar environments are also present in other fjords and these processes are probably of major importance for the redistribution of the fjord sediments. additionally, sediment reworking by currents is important in fjords (e.g. syvitski & macdonald 1982). the existence of such processes is indicated by the general coarser composition of the slope w i n n o y l n g 8 1 c u r r l l l l s 350 j fig. 23. diagram illustrating sediment types and processes in a spitsbergen fjord fed by a tidewater glacier (based on data from kongsfjorden). 146 anders elverhoi, (aiuind lenne and reinert seland and sill deposits compared with the composition of the basin deposits. the observed nepheloid layer may in part consist of this winnowed material. sedimentation rates further information on sedimentation rates can be obtained using the time elapsed since the deglaciation of the region. this kind of calculation has been done for fjords and coastal embayments in alaska, using till surface as the lower time marker (van huene 1966; molnia & sangrey 1979). such calculations, however, include the sediments deposited during deglaciation and may therefore give excessive rates. in svalbard the timing and extension of glacia tions during the weichselian are disputed (boul t o n 1979: troitsky et al. 1979: hughes et al. 1981; salvigsen & nydal 1981; miller 1982; boulton et al. 1982). most likely, only a minor expansion beyond the present-day margins took place along the western and northern coasts during the late weichselian (salvigsen 1977; boulton 1979; miller 1982; salvigsen & osterholm 1982). a more extensive glaciation has also been suggested (hoppe 1970; hughes et al. 1981). however, the last major advance beyond the present-day coast line probably occurred in the early weichselian, tentatively dated as ending 80-90 ka bp (salvig sen & nydal 1981; boulton et al. 1982; miller 1982). during the mid weichselian the glaciers probably did not expand significantly beyond their modern margins (troitsky et al 1979; boulton et al. 1982; miller 1982). in table 1 the sedimentation rates are listed, based on the available data on the weichselian glaciations for the lower boundary. for the north t u b k 1 sedimentation rates of acoustically transparent and semi-transparent sediments in fjords on the western and northern c o a m of spitsbcrgen. calculation of sediment thlckness i, based on a seismic velocity of 1500m/scc. t y p e of p r o b m u ayeface lower boundary r a t i o glacial sedimxt timf. mr sedimentation mr dated drainage/ coverage i n t h i c k n e s s d f f i l a c i a t i o n rate interval fjord a r e a drainage area ijxality i " m aqe bp mm/year o / o liefdeflorden 46 1 0 1 2 . 0 0 0 0 . 5 top lw till 6 4 1 veerenburgfjorden 1 0 1 5 1 0 1 2 . 0 0 0 1 . 5 top lw till 4 56 faudfjorden 8 1 2 1 0 1 2,000 1 .o top lw tlll 3 57 woodfiorden 10 80.000 0 . 1 toil w till i d 1 2 . 0 0 0 1.0 i c ~ lw till ~ _ _ xonqsfjorden 1""-r b s l n 1 . 3 , 20 1 0 till, 1 9 4 8 surge n 100 8 0 tlii, 1 8 6 9 s u r q e 5 0 1 0 0 organic v a r v 6 . 5 kongsf~orden i n n e r part of+ 1 2 2 0 1 0 . 0 0 0 1-2 top lw till central basin 1 7 0 . 6 0 . 1 top ew till top lw tlll 6 outer part of n o . o o o central bas," 6 101 2 , 0 0 0 2 ~~ ~~ kongsf]ordd]upet 0 . 7 5 1,73u!l60 0.4 i'r-4 7 x 1 ) 80,000 0.25 top ed till 1 0 1 2 , 0 0 0 top lw till 2 1 9 1 9 0.25 top ew till 10 80,000 0 . 1 top ew till 1 0 10-1 2 . 0 0 0 top lw till 2 0 80,000 20 1 0 1 2 , 0 0 0 2 top lw till isfiorden , o u t e r part i n n e r part 1 3 4 0 ivfma core) 6 1 0 . 0 0 0 0 . 6 ice-proximal d e w s 1 ts in the vema core 23-65 top lw tlll 2 0 0 4 0 0 10-20 till. surge d~ck~on f i o r d e n 7 . 5 1 0 . 0 0 0 0 . 8 > 2 0 0 y e a r s van hiienfprden . inner basin 5 35 outer basin* $ 80,000 0 . 2 5 top ew till top lw till 2 101 2 , 0 0 0 -~ data on drainage arca and glacial coverage are from liestdl and roland (per,. c o m m . ) . bediment thickness from 3 . 5 k h z echo-sounding profiles. + sediment thickness from rsopach map. glaciomarine sedimentation in soalbard fjord 147 ern fjords (except woodfjorden), dicksonfjor den, and the inner part of the main basin in kongsfjorden, the lower boundary has been dated to the late weichselian. in isfjorden and the outer parts of woodfjorden, kongsfjorden, and van mijenfjorden both a late and early weich selian age are indicated for the lower boundary. kongsfjorden. in the central and outer parts of kongsfjorden sedimentation rate differs by an order of magnitude, depending on whether a late or early weichselian age is assigned to the lower boundary (table 1). the outer part of kongsfjor den is close to kongsfjorddjupet, and based on the similarities in (1) bathymetry and hydrogra phy, (2) acoustical signature, and (3) sediment lithology and thickness, the sedimentation rates are suggested to be approximately uniform for the two areas. application of the depositional rate from core 121 in kongsfjorddjupet for the acoustically transparent unit in the whole region, gives an age for the lower boundary of 60,000 years bp, which corresponds to mid/early weichselian, implying that the outer part of kongsfjorden has not been covered by grounded ice during the mid and late weichselian. in kongsfjorden the sedimentation rate decreases two orders of magnitude away from the main sediment source. the lower input to the central and outer parts of the fjord is also partly due to the frequent confinement of the surface plume to the inner basin. field observations in 1979,1980, and 1981 indicated, however, that the plume extends to a position where the katabatic winds blowing down the glacier, counterbalance the more general wind direction in the region. additionally, tidal currents flowing in on the southern side forced the surface water to flow out through the northern outlet, which was frequently filled by icebergs. the fact that most of the sediment yield from kongsvegen (the main glacier in the kongsfjor den area) is trapped in the inner part of the fjord, is also seen from the sediment colour. the red coloured sediments derived from the old red beds of the eastern part of kongsfjorden’s drain age area are confined to the region inside station 114 (fig. 2), an area of about 100 km’. the lowering of the sedimentation rate down the fjord is also due to the ‘carrying potential’ of the surface sediment plume, i.e. a considerable part of the finer material in the surface plume may be carried out of the fjord without settling (syvitski & murray 1981). the other fiords. the ratio of drainage (fluvial and glacial) area to depositional area (or the area of the fjord) is relatively uniform (table l), which, combined with a relatively similar glacial coverage and bedrock geology (un/low meta morphic clastic rocks (flood et al. 1971; hjelle & lauritzen 1982) in the drainage areas, indicates the depositional rates to be comparable. addi tionally, all larger fjords are characterized by tributary fjords and inner basins which function as sediment traps for the main fjord. for the northern fjords (except woodfjorden) the depositional rates of 0.5-1.5 mm/years are comparable with those of kongsfjorden. the thicker sediment sequence in the central and outer parts of woodfjorden is similar to the outer part of kongsfjorden explained in terms of no glacia tion in the mid and late weichselian rather than a higher sediment input. concerning the inner part of isfjorden the vema core indicates a sedimentological change from ice proximal to basin deposits at a sediment depth of six metres. an early weichselian age for this boundary would give a markedly low sedimentation rate of 0.1 mm/year. alternatively, a late weichselian age for the lower boundary shows a rate of 0.6 mm/year which is more com parable with the values from kongsfjorden. according to this, late weichselian grounded ice may have extended into the main fjord rather than have remained in the tributary fjords as proposed by boulton (1979). in van mijenfjorden the late weichselian ice may have extended to akseloya or further, or has been confined to the central sill. in the latter case, part of the acoustically transparent unit in the outer basin in van mijenfjorden is lacustrine. the sedimentation rate in van mijenfjorden (based on a late weichselian ice extending to akseloya) is higher than for other fjords (table 1). this is attributed to the akseloya threshold which makes the fjord almost a closed basin. surge deposits in kongsfjorden minor basins with infill of coarser grained sediments are observed just outside the 1948 moraine in the inner basin. a similar infill is also found on the western slope of the sill south of lovcnoyane, outside the end-moraines of the 148 anders eluerhbi, biuind l l n n e and reinerr seland 1869 and 1948 surges. in van mijenfjorden a basin infill of coarser materials is located outside the position of maximum ice extent. the sedi mentation of thick meltwater deposits outside the ice front during a surge may be related to such factors as: (1) increased meltwater discharge due to fric tional heating during a surge (e.g. weertman 1969), ( 2 ) radical change of the subglacial meltwater channels, or (3) erosion of glaciomarine sediments reworked by the surging glacier. so far no marginal feature, end-moraine or surge deposit corresponding to the 1869 moraine on land has been observed in the fjord. from the distribution of its moraine on the adjacent shore, the 1869 surge in this area was characterized by thin ice. the lack of surge deposits may be attri buted to the ice almost boating in its outer parts. conclusion investigations of glacial fjords in western and northern spitsbergen by means of high resolution acoustic profiling and sediment sampling show 5 to 20 m thick acoustically transparent sediments with distinct bottom echoes in the fjord basin. these muddy to sandy muddy sediments with a relatively low content of clasts ( < 5 % , ) are formed mainly from materials settled from the turbid surface overflow, and deposited at rates between 0.5 and 1 mrq'year. the ice-rafted component is of volumetrically minor importance. on slopes and sills, semi-transparent or acoustically opaque sediments with prolonged bottom echoes are found, reflecting their coarser composition rela tive to the basin deposits. the slope and sill deposits are subject to reworking by currents and gravity flow processes as slide. slumping and sedi ment creep, while turbidity current deposits seem to be of minor importance. sedimentation rate increase up fjords towards glaciers. in kongsfjorden, the main study area, the rate is 50-100 mm/year at a distance of 10 km from the front of kongsvegen (a 1000 km2 gla cier). this rate is characteristic of a fjord bed area of 15 km2, which is 1/6 of the area dominated by kongsvegen sediments. this in turn shows that about 90% of the sediment imput from kongs vegen is deposited relatively adjacent to the ice the glaciers at svalbard advance periodically by a surge, reworking and compacting glacio marine sediments. during a surge considerable amounts of subaqueous outwash sediments may be deposited in front of the glacier. acknowledgements. financial support for this study was pro vided by elf aquitaine norge a / s and the norwegian polar research institute, which also provided the logistical platform. we are grateful to james syvitski. john milliman. william wiseman jr.. ross powell, and colleagues at the norwegian polar research institute for their constructive comments and critical reviews. adrian read corrected the english text and is thanked for his critical comments. bengt christensen kindly determined the type of gastropode. the geological institute, university of bergen, provided seismic (boome) equipment and technical support during the field work in 1980. references baranowski. s . 1977: the subpolar glaciers of spitsbergen seen against the climate of this region. wroclaw, wydawnictwa universytetu wrochawskeiyo. resulrs of investigation of the polish scientific spitsbergen e.rpedition 3 . 93. blindheim. j. & ljqen. r . 1972: on the hydrographic con ditions in the west spitsbergen current in relation to ice distnbution during the years 19561963. pp. 3 3 4 1 in karls son. t. (ed.): sea ice. conference proceedings, reykjavik. boulton. g . s . 1979: glacial history of the spitsbzrgen archi pelago and the problem of a barents shelf ice sheet. boreas 8. 31-57. boulton. g . s . . baldwin, c . t . . peacock, j. d . , mccabe, a . m . . miller. g . , jarvis, j . , horsefield, b . , worsley, p . , eyles, n . , croston, p. n.. day, t. e . , gibbard, p.. hare, p. e. & von brunn. v . 1982: a glacio-isostatic facies model and amino acid stratigraphy for late quaternary events in spits bergen and the arctic. nature 2y8, 437-441. damuth. j. e . 1975: echo character of the western equatorial a t l a d c floor and its relationship to the dispersal and distri bution of terrigenous sediments. marine geology 18, 17-45. damuth. j. e . 1978: echo character of the norwegian-green land sea: relationship to quaternary sedimentation. marine geology 28. 1-36. damuth. j . e. 1980: use of high-frequency (3.5-12 khz) echo grams in the study of near-bottom sedimentation processes in the deep sea: a review. marine geology 38. 51-75. damuth. j . e. & hayes, d. e. 1977: echo character of the east brazilian continental margin and its relationship to sedi mentary processes. marine g e o l o g y 24, m73-m95. elverhei. a . . liestel. 0. & nagy. j . 1980: glacial erosion, sedimentation and microfauna in the inner part of kongsfjor den. spitsbergen. norsk polarinrtitutt skrifter no. 172. 33 58. farrow, g . e . . syvitski, j . p. m. & tunnicliffe, v . 1983: suspended particulate loading on the macrobenthos in a highly turbid fjord: knight inlet. british columbia. can. j . fish. a q u a t . sci. 40, 273-288. flood. b.. nagy, j . & winsnes. t. s . 1971: geological map, svalbard 1:500.000. sheet ig spitsbergen, southern part. norsk polarrnstitutt skrifrer n o . 154a. g a m m e l s r ~ d . t. & rudels, t . 1983: hydrographic and current measurements in the fram strait, august 1981. polar front. reseorch 1 n.s. ( 2 ) , (this volume). glaciomarine sedimentation in svalbard fiord 149 gilbert, r . 1982: contemporary sedimentary environments of baffin island, n.w.t., canada: glaciomarine processes in fjords of eastern cumberland peninsula. arctic and alpine research 1 4 , 1-12. haga, 0. 1978: morenemasser i dddis etter et breframstdr i van mijenfjorden, spitsbergen. unpub. cand. real. thesis, univ. of oslo. 88 p p , hjelle, a. & lauritzen, 0. 1982: geological map, svalbard 1:500.000. sheet 3g spitsbergen, northern part. norsk polarinstitutt skrifter no. 154c. holtedahl, h . 1975: the geology of the hardangerfjord. west norway. nor. geol. unders. 323, 1-87. hoppe. g . 1970: the wurm ice sheets of northern and arctic europe. acta geographica lodziensia 24, 105-115. hoskin. c. m. & burrell. d . c. 1972: sediment transport and accumulation in a fjord basin, glacier bay, alaska. j. geol, 80, 359-551. hoskin, c. m . , burrell. d . c. & freitag, g . r . 1978: suspended sediment dynamics in blue fjord, western prince william sound, alaska. estuarine and coastal marine science 7 , 1 16. hughes. t. j., denton. g . h . , andersen, b . g . , schilling, d. h., fastook, j. l. & lingle, c. s. 1981: the last great ice sheets: a global view. pp. 263-317 in denton. g. h . & hughes t . j . (eds.): the last great ice sheets, john wiley & sons. king, l. h . 1967: use of a conventional echo-sounder and textual analyses in delineating sedimentary facies: scotian shelf. can. 1. earth sci. 4 , 691-708. kraft, l. m. jr., campbell, k. j. & ploessel, r . m. 1979: some geotechnical engineering problems of upper slope sites in the northern gulf of mexico. pp. 25-42 in doyle, l. j . & pilkey. 0. h . j r . . (eds.): geology of continental slopes. soc. econ. palent. min. spec. publ. 2 7 , tulsa, oklahoma. liestdl. 0. 1969: glacial surges in west spitsbergen. can. j. earth sci. 6 , 895-897. liestel. 0. 1975: glaciological work in 1975. norsk polar institutt arbok 1975. 147-158. mackiewicz, n . e. & powell, r . d. 1982: laminated ice proximal glaciomarine sediments. eleventh international congress on sedimentology, hamilton, canada, abstracts, 74. miller, g . h . 1982: quaternary depositional episodes, western spitsbergen, norway: aminostratigraphy and glacial history. arctic research and alpine research 14, 321-340. molnia, b. f. & sangrey, d . a . 1979: glacially derived sedi ments in the northern gulf of alaska geology and engi neering characteristics. proc. 1979 offshore technology con ference, otc-3433, 2 , 647-655. molnia, b. f. & hein, j. g. 1982: clay mineralogy of a glacially dominated, subarctic continental shelf: northeastern gulf of alaska. j. sed. pet. 5 2 , 515-527. myhre, l. 1974: a computer program for grainsize distribution analyses. publ. 44, ntnfs continental shelf project, 1-22. ovenshine, t , a , 1970: observations of iceberg rafting in glacier bay, alaska. and the identification of ancient ice rafted deposits. geol. soc. a m . bull. 81, 891-894. powell, r. d . in press: glaciomarine sedimentation processes in glacier bay, alaska. i n molina, b. f. (ed.): glacial marine sedimentation, plenum. prior, d . b.. wiseman, w. j . jr. & bryant, w r. 1981: submarine chutes on the slopes of fjord deltas. nature 290, 326-328. repp, k. 1979: breerosjon, glasio-hydrologi og materialtrans port i et hmyarktisk miljg, brdggerbreene, vest-spitsbergen. unpub. cand. real. thesis, university of oslo. 136 pp. rowan. d . e., pewc, t . l . , pcwe. r . h . & stuckenrath, r . 1982: holocene glacial geology of the svea lowland, spits bergen, svalbard. geogr. ann. 64 a , 35-51. salvigsen, 0. 1977: radiocarbon datings and the extension of the weichselian ice-sheet in svalbard. norsk polarinstitutt arbok 1976, 209-224. salvigsen, 0 . & nydal, r . 1981: the weichselian glaciation in svalbard before 15.000 bp. boreas 10, 43s446. salvigsen, 0. & osterholm. h . 1982: radiocarbon dated raised beaches and glacial history of the northern coast of spits bergen. svalbard. polar research 1 . 97-115. schei, b., eilertsen, h . g . , falk-larsen, s . , gulliksen, b. & taasen, j . p. 1979: marinbiologiske undersdkelser i van mijenfjorden (vest-spitsbergen) etter oljes0llekasje ved sveagruva 1978. tromsd mlcreums rapportserie, naturuiten skap. nr. 2 . universitetet i troms0, 50 pp. schytt, v. 1969: some comments on glacier surges in eastern svalbard. can. j. earth sci. 6 , 867-873. syvitski, j . p. m. & murray. j . w. 1981: particle interaction in fjord suspended sediment. marine geology 3 9 , 215-242. syvitski, j. p. m. & macdonald. r. d . 1982: sediment char acter and provenance in a complex fjord: howe sound, british columbia. can. j. earth sci. 19. 1025-1044. thorarinsson, s . 1969: glacier surges in iceland, with special references to surges of bruarjokull. can. j . earth sci. 6 , 875-882. troitsky, l.. punning, j . m.. hiitt, g . & rajamae, r . 1979: pleistocene glaciation chronology of spitsbergen. boreas 8, 401-407. van huene, r. 1966: glacial-marine geology of nuka bay, alaska, and the adjacent continental shelf. marine geology 4 , 291-304. weertman, j . 1969: water lubrication mechanism of glacier surges. can. j. earth sci. 6 , 929-939. research note 14 raised beach deposits and new prins karls forland, western svalbard c ages from pricepynten, + torbjorn andersson this note reports the occurrence of two generations of 14c dated raised beach deposits at pricepynten. southern prins karls forland, western svalbard, dated to < 12 kya and >30 kya. in addition two new 14c ages of ca. 9.2 and 1.8 ky are presented from myrilus eclulis and a buried peat deposit, respectively. t. aiidersson. pirrstugun. moriing, se-153 9.5 jljrmi, sweden. fieldwork on southern prins karls forland in the summer of 1997 focused on geomorphologic investigations in the pricepynten area (fig. i ) . the study is part of a project on the late quaternary history of prins karls forland, western svalbard. previous results within the project from central and northern prins karls forland are reported i n andersson et al. (1999, in press) and bergsten et al. (1998). f i g . 1. svnlbnrd base map with localities mentioned i n the text. previous investigators, e.g. salvipsen (1977), suggested that the occurrence of multiple genera tions of raised beach deposits, with well-preserved pre-late weichselian beach terraces. at localities on the west coast of svalbard could indicate the presence of ice-free areas during the late weich selian glacial maximum. based on studies of elevation, degree of morphologic preservation, c ages. molluscan amino acid ratios and soil profile development, up to three generations of raised beaches have been identified on brmgger halvcaya (brggger peninsula). western spitsbergen (forman & miller 1984). definitive ages for the raised beach sequence for br~ggerhalv#ya are provided by ''c ages of >36 ky and 13-9 ky above and below the late weichselian marine limit (lwml), respectively (forman et al. 1987). on central and northern prins karls forland, palaeotemperature estimates, derived from amino acid ratios, indicate subaerial polar desert condi tions with temperatures of -2o't during the time interval ca. 70-10 kya (andersson et al. 1999, in press). on northern prins karls forland this is further emphasized by a horizon of intense weathering and frost-shattered pebbles and cob bles, stratigraphically sited between ca. 70 kya deltaic deposits and holocene emergence deposits (andersson et al. in press). the results from central and northern prins karls forland conflict with a recent synthesis by landvik et al. (1998) which concluded that the late weichselian barents sea i4 andersson 2000: polrir research 19(2). 27 1-273 17 1 fig. -7. a distinct and well-preserved pre-late weichselian raised beach ternice at 50 m asl. the terrace i, built against the mountain slope and it can be followed for more than 100 m i n the terrain. the person is 1.85 m tall. ice sheet expanded on a broad front out to the continental shelf edge, 50-100 km off the present west coast, and that only some of the > 1000 m as1 mountain peaks on prins karls forland could have remained ice-free. i n this context, the main aim of this note is to report the observation of multiple generations of raised beach deposits and asso ciated “c ages from pricepynten, southem prins karls forland, that may indicate that the area remained ice-free during the late weichselian. two generations of raised beach deposits the observation of multiple generations of raised beach deposits on the west coast of svalbard have been reported by salvigsen (1977. 1979), boulton (1979). salvigsen & nydal (19811, forman & miller (1984) and forman (1989, 1990). on southern prins karls forland, salvigsen (1977) reports vague pre-late weichselian raised beach deposits up to approximately 50 m asl. similar features on northern prins karls forland are reported with potential minimum ages of >30 k y (salvigsen 1977). on central prins karls forland, pre-late weichselian raised beach de posits are constrained by well-developed soil profiles with bi-horizons of >8ocni and a minimum limiting ams “c age of >40 ky (anderson et al. 1999). geomorphologic fieldwork during the summer of 1997 i n the pricepynten area. southern prins karls forland (fig. i ) , verified the existence of two generations of raised beach deposits. a well preserved series of raised beaches extend from the present-day coastline to the lwml at 36 m asl. a minimum limiting age of ca. 11.4 ky is inferred for the formation of the lwml on this part of prins karls forland (forman 1990). discontinuous beach deposits rise from the lwml at 36 m as1 to approximately 50 m asl. reworked shell fragments collected from soil pits dug into a distinct and well-preserved beach terrace at 50 m asl. (fig. 2 ) and submitted for ams ‘‘c dating, yielded ages of 28 530 f 420 and 33 820 f 815 years bp (table 1). the carbonate i n the shell fragments may have exchanged with moving groundwater, introducing modern carbon, and the reported ages are con sidered minimum age estimates. a sub-recent marine transgression the issue of a modem transgression i n the area has been discussed by feyling-hanssen (1955 1. blake (1961), forman et al. (1987) and forman (1990). among others. “c dates on whale bones and terrestrial peat buried by modem storm beach gravels from southern prins karls forland and hermansengya. respectively, indicate that sea level rose to its present position ca. 2-1 kya (forman 1990). on southern prins karls forland, 1.5 km south of pricepynten, a horizon of peat of terrestrial origin is exposed in section at 3.5 m asl. the peat horizon is laterally continuous and traceable along the section for more than 50 m and i t is overlain by an up to 50cm thick deposit of storm beach gravels. a sample of the buried peat yielded an ams “c age of 1760 -i 70 years bp (table 1) and further supports the notion that sea level rose to its present position ca. 2-1 kya (forman 1990). a new i4c age on mytilus edulis paired and well-preserved shells of m . rclirlis occur i n stratigraphic position i n sections 1.5 km south of pricepynten. a sample of paired shells submitted for ams “c dating yielded the corrected age of 9130 f 65 years bp (table 1). the reported age is almost identical to a former age determination of 8955 & 90 years bp of m . rdulis from pricepynten (forman 1990), and is within close range of the first immigration of m . edidis to the west coast of svalbard by ca. 9.5 kya (salvigsen et al. 1992). 172 raised beach deposits and new ‘-!c ages from pricepynten. prim karls forland tnble 1. ams "c ages expressed as years bp, pricepynteii. prins karls forland. svalbard. corrected '"c field i4c age iu age f i u years 6 "c no. lab no." yeara b p bp" oiw ' dated material m as! tapkf ua-12911 33 820 f 815 c3.21 \hell fragment from raised beach teracej1 50.0 007-97 tapkf ua-12451 28 530 f 420 +2.59 shell fragment from raised beach terrace" 50.0 007-97 tapkf ua-12455 9600 f 65 9130 2 65 -0.73 paired valve of mytilrrs edulis from littoral 2.0 0 12-97 sediments" tapkf ua-12456 1760 f 70 -27.77 terrestrial peat from stratigraphic section5' 3.5 014-97 "ua numhers refer to accelerator mass spectrometry (amsi ''c dates perforrned at the & w r o m laboratory. uppsala university, "corrected for a marine reservoir effect of 470 years [sruvier & braziunas 1993). "as per convention all i4c ages ha\w been normalized 111 -25%0 (5 "c. "reported ages are on a single shell fragment analysis. pv-treatment of shell fragment prior to dating include a twofold leach i n "pre-treated with 1 % hot hci and 1 % hot naoh. the insoluble p l ~ l has been dated. sweden. 0.5 m hci. the inner fraction has been dated. a ~ . k f i o ~ \ l r ~ / g e i n p r , t s . ~ the author wants to thank the norwegian authorities for permission to carry out fieldwork in the forlandet nasjonalpark. this work, carried out when the author was affiliated with the university of gijteborg, is a part of the s w d i s h arctic research programme (swedarctic). crib erous support has been procided by the swedish natural scicnce research council (nfr), the norwegian polar in\titute. the swedish polar reaearch secretariat, the royal swedish academy o f sciencesnh. nordstroms fund. the swedish society for anthropology and geography. the ymer-80 foundation. and the earth sciences centre. university of gbtehorg. thanks also to p. saniuelsson for helpful and appreciated asislance during the 1997 field season. the paper benefited from the reviews by 0. salvigsen and one anonymous referee. references andersson. t.. forman. s. l., ingdlfsson, 0. & manleq. w . f. 1999: late quaternary environmental history of central prim karls forland, western svalbard. b o r i y s 28. 292-307. andersson, t., forman, s. l., ingolfsson, 0. & manley, w. f. in press: stratigraphic and morphologic constraints uii the weichselian glacial history of northern ptins karls forland, western sbalbard. geogr. ann. bergsten. h.. andersson. t. & ingolfsson, 0. 1998: forami niferal stratigraphy of raised marine deposits. repre\enting isotope stage 5. prins karls forland. western svalhard. p o h res. 17, 81-91. blake. w.. jr. 1961: russian settlement and land rise in nordaustlandet, spitshergen. arctic 14. 101-1 i i . boulron. g . s . 1979: glacial history of the spinhcrgen archipelago and the problem of a barents shelf ice sheet. boreus 8, 31b.57. feyling-hanssen. r. w. 1955: stratigraphy of the marine late pleistocene of billefjorden. vestspitsbergen. nur. polurit?.tr. skr. 107. forman, s. l. 1989: late weichselian glaciation and deglacia tion of forlandsundet area, western spitabergen, svalbard. boriws 18. 5 1-60. forman. s. l. 1990: post-glacial relative fen-level history of northwestern spitsbergen. svalbard. g e n l . soc. am. bull. 102. 1580-1590. forman, s. l., mmn. d. &miller, g. h. 1987: late weichselian m d holocene relative sea-level history of br@ggerhalv@ya, spitsbergen. svalbard archipelago. q u i t . re.s. 27. 11-50. forman. s. l. & miller, g. h. 1984: time-dependent soil morphologies and pedogenic proceases on raised beaches. broggerhalvdya. spitsbergen. svalbard archipelago. a m . a l p . r r s . 16. 381-394. landvik. j . y., bondevik, s.. elverhbi. a., fjeldskaar. w., mangerud. j., siegert, m. j . , salvigsen, 0.. svendsen. j.-i. & vorren. t. 0. 1998: the last glacial maxiinurn of svalbard and the barents sea area: ice sheet extent and configuration. qriu/. sci. rev. 17. 43-76. salvigaen, 0. 1977: radiocarbon datings and the extension of the weichselian ice-aheet i n svalbard. nor. poluriiur. . & / > . 1976. 209-223. salvigsen. 0. 1979: the last deglaciation of svalbard. borrtrs 8. 229-23 i . salvigsen, o., forman, s. l. & miller. g . h. 1992: thermo philous molluscs on svalhard during the holocene arid their paleoclirnntic implications. p o / w re$. / i , 1-10, salvigsen. 0. & nydal. r. 1981: the weichzelian glaciation i n svalbard before 15,000 b.p. borens 10. 3 3 3 4 3 6 . stuvier. m. & braziunas, t. f. 1993: modelling atmospheric ijc intluences and '"c ages of marine samples to 10.000 bc. radiocc7rbon 25, 137-1 89. a n d e r \ \ o n 2000: polar resenrch z9(2), 211 -773 213 the distribution and diel movements of brunnich’s guillemot uria lomvia in ice covered waters in the barents sea, february/march 1987 vidar bakken bakken, v . 1990: the distribution and die1 movements of brunnich’s guillcmot uria ~omoiu in icc covered waters in the barents sea, february/march 1987. polar research 8 , 55-59. the distribution of briinnich’s guillemot in ice covered waters and near the marginal ice zonc in thc southern part of the barents sca was mapped from ship and helicopter in february/mdrch 1987. high densities of briinnich’s guillcmot (up to 1,300 ind./km*) were found in ice leads. the density of birds was especially high over shallow hanks where the sea depth was 4&80 m. a diel movement was also recorded. in the evening the birds left the leads and flew south. next morning they returned to fccd in the open leads. how far they migrated is uncertain, but possibly they flew down to the open sea or to leads close to the marginal ice zone. the migration may have been a mcans of avoiding to becomc trapped if leads closed after dark. vidar rakken, norsk polarinsriturt. p . o . box 158, n-1.330 oslo lufthaon, norway; october i989 (revised february 1990). the brunnich’s guillemot is one of the most numerous seabird species in the barents sea. breeding colonies are found on the norwegian coast (only in small numbers), in the svalbard area and in the soviet territories (frans josef land, novaja zemlja and the murman coast) (fig. 1) (norderhaug et al. 1977; golovkin 1984; mehlum & fjeld 1987). more than 600,000 pairs breed in the svalbard area (mehlum & fjeld 1987; bakken & mehlum 1988; knutsen et al. 1988; kempf & sittler 1988), while according to golovkin (1984), the total breeding population in the soviet territories is more than one million pairs. ringing recoveries have shown that briinnich’s guillemots breeding on the west coast of spits bergen and on the murman coast migrate towards waters southwest of greenland in winter (nor derhaug et al. 1977; kampp 1988). despite that more than 50,000 brunnich’s guillemots have been ringed on novaja zemlja (uspenski 1958), only a few have been recovered from greenland (salomonsen 1967,1971; kampp 1988), and many probably stay south of the ice covered areas in the eastern part of the barents sea during the winter (uspenski 1958). counts of seabirds in the southern barents sea in 1986-1988 have shown that the brunnich’s guillemot was a common species south of the ice covered waters in winter (anker-nilssen et al. 1988). in early spring, high densities of brunnich’s guillemot have been recorded in leads near the breeding colonies at svalbard (norsk polar institutt unpublished), but if they also exploit the ice covered waters in winter is unknown. in the bering sea high densities of guillemots have been observed in march, both in leads and near the marginal ice zone (irving et al. 1970). bj0rne ya 1 3 land fig. 1. map of the barents sea. 56 v . bakken in this paper i present results of counts of brunnich's guillemots in the ice covered waters in the barents sea in february/march 1987, during which period a diurnal migration was recorded. the possible causes for this migration are discussed. the ice conditions in the barents sea most of the ice in the barents sea is formed locally (vinje 1985). during the winter, it gradu ally extends southwards, and surrounds the breed ing colonies in the northern part of the barents sea (svalbard, frans josef land and novaja zemlja). however, the extent of the ice cover vanes greatly from year to year (fig. 2). the ice drift is influenced mostly by the wind, and the occurrence and distribution of open leads are highly dependent on wind speed and direction (vinje 1985). southerly winds compact the ice and close the leads, while northerly winds have the opposite effect. there are no areas within the ice covered waters which are permanently open during the winter period. december january february march fig. 2. maximum and minimum extension of sea ice in the barents sea in december-march based on long-term russian observations (after ussr ministry of defence 1980). methods counts were made from k.v. 'nordkapp', a norwegian coastguard vessel, and from a heli copter which was based on the ship. ship-based counts were made in daytime from one side of the bridge (16 m a.s.1) by a method described by tasker et al. (1984). when the ship was anchored, counts-of flying guillemots were made in the morn ing and evening from an observation platform (26 m a.s.1.). counts from the helicopter were made at a speed of c. 90 knots and at a height of c. 200 feet. two observers, one on each side, recorded birds seen in a 200 m wide (100 m on each side of the helicopter) transect. 18 71 9 0 0 0 0 0 d l" d ln a ln a00 e oe d l" d m 2 m a00 e oe 7 8 .o 11 .o 78 .o 17 .o 16 .o 15 .o 14 .o 9 9 9 9 9 9 s ln 0 ln l" a m 16 .o 11 .o 16 .o 1s .o l i . 0 0 none @ 1.0 10.0 0 0.1 0.3 q 10.0 30.0 q 0.1 1.0 0 10.0 100.0 0 1 . 0 1.0 more ?han 100.0 fig. 3. densities (number of birds per km2) of briinnich's guillemots observed from the boat (top) and helicopter (bottom) in the ice covered waters and close to the marginal ice zone in the barents sea, february/march 1987. distribution and die1 movements of briinnich's guillemot 57 the areas covered by the ship and helicopter surveys are shown in fig. 3. the data presented were collected from 27 february to 8 march. results the distribution of briinnich's guillemot was patchy in the ice covered waters, with lower den sities of birds in the eastern part of the study area (fig. 3 ) . the highest densities (up t o 1,300 birds/ km2) were seen in leads south and west of hopen (fig. 4). in this area there are shallow banks with sea depths from 40 t o 80 m, as compared to depths of c. 150 to 300m in the eastern sector. the distance from this area to the southerly marginal ice zone was about 150km. open leads were found throughout the area investigated. in the western part of the study area, between hopen and b j m m y a (fig. 4), we noted a distinct migration of briinnich's guillemots every morn ing and evening. just before dusk, the guillemots left the leads and flew south. in the morning they returned, and stayed in the leads for 7-10 hours. at night, there were almost no guillemots left in the area. the main northerly migration took place between 0700 and 1000 hrs. and the southerly migration between 1400 and 1700 hrs. (gmt). numbers flying past one side of the ship were counted three times (twice in the morning and once in the evening) (table 1). the total number of birds migrating was much higher than shown in table 1. during the survey, which lasted 14 days, the ice distribution changed greatly, with a general eastward shift of the western edge of the marginal ice zone (fig. 4). this change also influenced the distance from the main area, where the guillemots were observed southwest of hopen, to the mar ginal ice zone. in the last part of the survey, the distance to the western marginal ice zone was about the same as t o the southern marginal ice zone (fig. 4). one night during this period the fig. 4. the study area with the positions of the marginal ice zone at the start and at the end of the survey. the arrows indicate where and in which direction a diurnal migration of briinnich's guillemots was registered. the arrows pointing north are morning migrations and the arrow pointing south is an evening migration. thc dotted area indicates where the highest densities of briinnich's guillemots in leads were observed. crew on the bridge observed 'large flocks' of briin nich's guiliemot in the ship's search-light in big leads close to the western marginal ice zone. because no migration observations were made the previous evening or the next morning, i do not know if there also was a shift in the migration direction. discussion the high densities (up t o 1,300/km2) of briin nich's guillemots show that the southern parts of the ice covered waters of the barents sea were important for this species in februarylmarch. when passing the breeding colonies on hopen and bj@rncbya in the helicopter, no birds were observed on the breeding ledges which were table 1. three counts of migrating brunnich's guillemots observed on one side of the ship in the barents sea, february/march 1987. date time (gmt) position number of migrating birds direction 27 feb. 0740-1140 74"40'n 21"56'e 6,440 north/northwest 04 mar. 14w1600 76"20'n 25"oo'e 7,903 south/southeast 06 mar. 070c-1000 76"05'n 23"40'e 10,564 north/northwest 58 v. bakken covered with snow. hence, the occurrence of the guillemots in the ice covered waters was probably not connected to the use of the colony prior to the breeding season. in the barents sea, the formation of leads is almost totally dependent on the wind (vinje 1985). meteorological data from the southern part of the barents sea during a 30 year period show that the predominant wind-direction in winter is from the north-east (steffensen 1982). leads form on the leeward side of the island (t. vinje pers. comm.); hence, the probability of finding open leads southwest of hopen in winter is high. here tides probably also influence their formation, particularly in shallow areas where currents may be faster (t. vinje pers. comm.). the area may thus be of great importance for briinnich’s guillemots when the sea is otherwise covered by ice. leads may similarly form south of the islands further north (spitsbergen and edgeoya), but if the birds have to spend the night in open water the distance to the marginal ice zone is much longer. we have few data showing where the birds spent the night, but two observations indicate that the birds migrated to the marginal ice zone or to big open leads close to it. birds observed on a northerly morning migration near bjornoya were only a few km from the marginal ice zone (fig. 4). the night observation of ‘large flocks’ in open water near the western marginal ice zone also suggests a daily migration to this area. the evening migration from the ice covered waters could be caused by the danger of being trapped in the ice at night when leads may close. because of small wingloading (ruppel 1975), guillemots need considerable room to take flight from the water. during other surveys in ice covered waters in the barents sea, i have observed brunnich’s guillemots trapped in small leads and being unable to take off. in strong winds brunnich’s guillemots may manage to get alight from an icefloe, but in most cases they fail (per sonal observation). this die1 movement was only observed over a four day period when the ship stayed south and west of hopen, and i do not know if this migration is the regular pattern throughout the winter. if the birds depend on light for feeding in the ice covered waters, it will probably be impossible to exploit these areas in december and january because of the dark period. at hopen the sun is below the horizon from 2 november to 9 febru ary. a similar die1 movement for briinnich’s guillemots in ice covered waters has not pre viously been recorded, but there are earlier obser vations of high densities of guillemots near the marginal ice zone and in leads elsewhere (irving et al. 1970; divoky 1979; bradstreet 1980, 1982). the profit of feeding in the leads must have been high in relation to a daily return flight of up to 300 km (assuming they flew from the marginal ice zone). during our survey, the feeding con ditions in the leads were good. stomach analyses of 30 brunnich’s guillemots shot in the leads showed that the staple food was the amphipod parathemisto libellula and the polar cod bor eogadus saida (f. mehlum & g. gabrielsen pers. comm.). the mean body weight of the birds was 1,066 grams (sd = 113, n = 30), which is among the highest recorded during the year i n the sval bard area (f. mehlum & g. gabrielsen pers. comm. ; personal observation). stomachs of birds shot in open water near the marginal ice zone in the same time period contained mostly polar cod and amphipods, but the samples were well digested (erikstad 1990), suggesting that the birds had caught the food earlier (and possibly else where). gulliksen & lonne (1989) have shown that the sympagic fauna in this area is rich in polar cod and amphipods, and these resources are perhaps easier to catch for the birds than prey in the open sea at this time of year. this may explain why the guillemots migrated into the ice covered waters each day. acknowbdgemenn. -thanks are due to geir wing gabrielsen and egil soglo who helpcd counting birds. i am grateful to geir wing gabrielsen and fridtjof mehlum for letting me use their unpublished data and for thcir comments on the manuscript. 1 am also grateful to kjell einar erikstad, rob barrett and an anonymous referee for valuable comments. rob barrett also improved the english. many thanks to the crew and helicopter pilots on the coastguard vcssel k/v ’nordkapp’ for their help and hospitality. ‘this study was financed by the norwegian department of oil and energy as a part of an environmental impact analysis in connection with planned oil/gas drilling in the southern part of the barents sea. references anker-nilssen, t.. bakken, v. & strann, k-b. 1988: kon sekvensanalyse olje/sjchfugl ved petroleumsvirksomhet i barentshavet s0r for 74”30’n. v i l f r p p o r f 46. 98 pp. +appendix. distribution and die1 movements of brunnich's guillemot 59 bakken, v. & mchlum, f . 1988: akup-sluttrapport. sjdfugl undersvtkelscr nord for n7c/bjvtrndya. norsk polarinst. rapportserir 4 4 . 127 pp.+appendix. bradstreet, m. s . w . 19x0: thick-billed murres and black guillemots in the barrow strait, n.w.t., during spring: diets and food availability along ice edges. cun. j . z o o / . 58, 2120 2140. bradstreet, m. s . w . 1982: occurrcncc, habitat use, and behaviour of scahirds, marine mammals, and arctic cod at the pond inlct ice edge. arctic 35, 28-40, divoky, g . j . 1979: sea ice as a factor in seabird distribution and ecology in the beaufort, chukchi, and bering seas, pp. 7-19 in bartonek, j. c. & nettleship, d . n. (eds.): conservation of marine birds of northern north amcrica. fkh wildl. seru. res. rep. 11. erikatad, k . e. 1990: winter diets of 4 seabird species in the barenls sea after a crash in thc capelin stock. polur biol. (in prcss). golovkin, a. n . 1984: seahirds nesting in the ussr: the status and protection of populations. pp. 473-486 in croxall, j . p . , evans, p. g . € i . & schreiber, r . w . (eds.): staius and conseriiation of the world's seabirds. k b p techn. publ. 2 . gullikscn, b. & ldnne, 0. j . 1989: distribution, abundance, and ccological importance of marine sympagic fauna in the arctic. rapp. p.-v, reun. cons. inr. explor. mer 188, 133 138. irving, l . , mcroy, c. p. & burns, j . j . 1970: birds observed during a cruise in the ice-covered bering sea in march 1968. condor 72, llll112. kampp, k . 1988: migration and winter ranges of brunnich's guillemots uria lomuiu breeding or occurring in greenland. dunsk o m . tidsskr. 82, 117-130. kempf, c. & sittler, b. 1988: ccnsus of breeding seabirds on the northwest coast of svalbard 1973 and 1978. polar reseurrh 6 , 195-203. knutsen, l. o . , fjeld, p. e. & olsson, 0. 1988: sjdfugl undersvtkelser pa 0st-spitsbergen, svalbard, mcd kon sckvensvurdering av aktivitet p i haketangen. pp. 79-1 14 in prestrud, p. & 0ntsland. n. a. (eds.): miljdunders~kelser i tilknytning ti1 petroleumsvirksomhet p i svalbard 19x7. norsk polarinst. rapportserie 41. mchlum, f . & fjeld, p. e. 1987: catalogue of scahird colonies in svalbard. norsk polarinst. rapportserie 35. 222 pp. nordcrhaug, m., brun, e . & mollen, g . u . 1977: barents havcts sjdfuglressurser. norsk polarinst. meddelelser 104. 119 pp. ruppcl, g . 1975: fugle fm-digheter, flukt og fart. lademann. 184 pp. salomonscn, f. 1967: fu,qieiie p6 gr@nlurrd. khodos. 341 pp. salomonsen, f. 1971: recoveries in grccnland of birds ringed abroad. medd. o m grgnlund 191. 52 pp. stcffcnsen, e . 1982: the climatc at norwegian arctic stations. klimu 5 . 44 pp. tasker, m. l . , hope jones, p., dixon, t. j . & blake, b . f. 1984: counting seabirds at sca from ships: a review of mcthods employed and a suggestion for a standardized approach. auk 101, 561-577. uspenski, s . m . 1958: the bird bazaars of novaya zemlja. canadian wildl. seru. translations of rllssian game reports 4 . ottawa. 159 pp. ussr ministry of defence (gorskov, s . g. & faleev, v. 1. (cds.)) 1980: atlas of the oceans. the arctic ocean. vinje, t . 1985: drift, composition, morphologhy, and distri bution of the sea ice fields in the barents sca. norsk polarinst. skrifter 179c. 26 pp. research note the role of the west spitsbergen current in the formation of ice edge position alexander makshtas and igor podgorny makshtas. a . p. & podgorny, ]..a. 1991: the role of the west spitsbcrgen current in the formation of ice edge position. p d u r research 9(2), 207-210. the intensity of sea-ice interaction in the fram strait is estimated from hydrographic data by use of three different methods. preliminary results concerning fresh water formation rate are reported. a . p . m a k s h m and i . a . podgorny, arctic and antarctic research insriture. 38 bering st.. 199226 sr. petersburg. u.s.s. r. it is commonly accepted that advective heat fluxes in the atmos phere and the hydrosphere along with sea ice transport from the arctic ocean control in general the spatial ice distribution in the greenland sea. the advection of warm atlantic water appears to be the main factor in the formation of the ice edge position and the upper layer of low salinity water in the north east part of the fram strait, where the wesyspitsbergen current (wsc) intcracts very actively with the ice edge. the intensity of this interaction has been investigated by manyoceanographers. for example quadfasel et al. (1987) who used temperature and salinity profiles from two oceano graphical stations in the wsc (one at 77"30'n and one at 80"20'n). they estimated the influence of atlantic water on fig. 1 . location of all hydrographic stations used in the hori zontal maps. the solid line indicates the ice-breaker drift during operation of the two-day ice station. the dotted line indicates the ice margin position (may 1989). the ice edge formation and found the difference in the heat content in the upper i00 m layer between the two profiles to be 5.03 x lo8 j/ml with an associated salt deficit of 3 g/cm'. this might have been caused by the daily retreat of the ice edge of about 5 km with a thickness of 1.5 m. more recently unterstciner (1988) described the above pro cesses on the basis of a steady heat-balance model in which the ice edge was interpreted as a wedgc with a thickness changing from zero on the ice margin to 2.5 m at 150 km to the north. the relevant heat flux from the upper ocean layer to melting ice was estimated as being about to 300 w/m'. nevertheless, the data of vinje & finnekisa (1986) indicate considerablc ice aoe thicknesses immediately near the ice edge as being up to 2 m. on thc basis of these data and our own observations i n the area under study, wc suggested the wedge description to be rather questionable, and we have therefore tried to estimate the role of the wsc in the ice edge and upper layer formation anew, paying particular attention to the localization of the intensive ice melting. for this purpose, during the r/v otto schmidt cruise in may 1989 two oceanographical sections up and down the westcrn branch of the wsc were defined and a two-day ice station was established for collecting data. the study area and the station locations are shown in fig. 1. horizontal distributions of the main oceanographical charac teristics in the upper 100 m in the castcrn part of the fram strait are shown in fig. 2. one can see that t and s fields vary significantly from place to place. especially under the sea ice. the distribution of the heat content (q) in layers & 3 0 m and 3&100 m is similar to that of t and s near thc surface. the main dccrease of q takes place in the vicinity of the compact ice margin between 80"16'n and 80"03'n. this may he illus trated with the aid of table i . where "normalized" differences in q ( a q ) between several profiles of the first section (fig. 2a) are determined. the origin of the horizontal coordinate x corresponds to xv16'n. temperature and salinity profiles from two stations in the wsc (one at 80"16'n and one at xo"03'n) are plotted in fig. 3. 208 aiexnnder mriksktns & lgnr podgorriy the role of the west spitsbergen current in the formation of ice edge position 209 tubk 1. "normalized" differences a q (j/mi) at the section along the wsc (see fig 2) a z l a x g15.6 15 c 5 3 . 5 53.5-72.1 72.1-153 5 153 5-264.7 &30 370 -65 16 18 -2 3(!-50 -272 25 15 40 16 50-1ci) y 72 43 -12 10 100-200 -57 53 -102 37 7 note: a q is the average heat content change of a cubic metre seawater p e r one metre distance. a z ( m ) characterizes the upper and lower boundaries of a layer and ax (km) is the distance between two successful stations. s 34 t 0 1 i 3 i i 0 1 i 3 i i i '\ . . f i g 3 vertical profiles of temperature ("c) and salinity ( % a ) at stations 8732 (80"16'n, 4"05'e) and 8731 (80"03'n. k w e ) the iiioht intensive interaction between the wsc and sea ice appears to be in the upper 5 0 m layer. where aq has its maximum change. we suggest that variations of aq in the 50 200 m layer arc mainly linked to the uncertainty in determining q , and. perhaps, to eddy structures (johannessen et al. 1987). i t should be mentioned also that the heat transfer from the open ocean to the atmosphere which was determined from the ship's meteorological data using the algorithm proposed by makshtas et al. (1989) was quite close to zero (= 40 w/m') during the period of observations and has not been taken into consideration. fig. 2.horizontal distributions of main oceanographical charac teristics in the upper 100 m layer in the east area of the fram strait (may 1989): a. b surface temperature ("c) and salinity (you); c. d the same at 100111; e, f heat content (j/m2 x lor) in layers 0-30 and 3&100 m; ice concentrations: 0.1-0.2 (--), 0.9-1.0 (-,-); (+) station locations used in table 1; ( 0 ) -stations 8731 and 8732. let us examine the heat balance equation to evaluate the heat flux from the upper ocean layer upwards near the margin of sea ice: j t jt pwc, = -div f ( 1 ) where pn and c, are the density and the specific heat of sea water and f is the heat flux in the wsc. because of the weak temporal variability of the seawater temperature t near the ice margin, (1) may be rewritten as: where ii, denotes the northward average current velocity. we found the term df,/dx due to turbulence to be small in comparison with the term jfjjz and integrated (2) through the layer of the most intensive ice-sea interaction with the depth h: j h u, lo p,c,t dz = f, fh. ( 3 ) 210 alexander makshtas & 1gor podgorny so. using (3). taking u, = [ ) . i m/s ( a a g a a r d et al. 1985) and h = 50 m , and considering a heat rux through the stable pycno cline as very weak. h e can estimate f,, as 1600 w / m ' o n the hasis of table 1 this heat flux is suggested to be generally localized between wo3' and xff 16". where ice concentration changed from 11.5 to 1.0. direct measurements to the north of this region, where the two-day ice station wa\ located (fig. i ) . gave a n exper imental estimate of the ice bottom melting rate of about 2 . 5 cm! day, corresponding to f,, being only u p to yo wim'. t o prove our result we also used another approach. having examined the salt balance equation: where s, and s, arc the seawater a n d the sea ice salinities. and p, and h, the density and the spatially averaged thickness of sea ice. the method. being similar to that used by quadfascl c t al. (19x7). has been used again with s, = 2 7 ~ . h = 50 m and salinity profilcs. as plotted in fig. 3 . w e found the value of dh,!dt to he of 0 . 3 m/daq and the associated heat flux of 7(x) wim' as no! being remarkably different from the ahovc estimate. i t \hould he mentioned that o u r estimate of dh,,'dt d o e s not differ very much from that reported by josberger (1987). who carried out direct measurements of the ice melting rate in the marginal ice zonc and found i t to be u p to 0 5 m/day. o u r results sugge\t that the greater part of fresh water and heat fluxes in the northeastern area of the fram strait u c r e formed under thc narrow icc hclt with width ax = i5 k m run ning zonally along the compact ice margin. however. thcre is some uncertainty regarding this conclusion. it is possible that the oceanographical characteristics of the analysed stations simply corresponded t o the different water masses of the west spits hergen and the east greenland currents. to examine the a h w e results once again let us use the ice mass balance equation: dh dt h, u, = ax ( 5 ) here u, denotes the x-component of the drift. i f the advcction of warm atlantic water from the south. determining thc valuc of dh,/dt. and the advection of sea ice from the north keep ice edge stationary. ( 5 ) is true assuming h, = ? m . ax = i 5 km. we get u, = 5.6cm;s and 3.5 cm/s corresponding to f,, = 1600 wim' and 700 w!m! respectively these estimates of u, d o not differ very much from the value u, = 6.5 cm/s reported by vinje & finnekasa (1986) taking the northward transport in the wsc a t 79"n in the upper 5 0 m layer as cqual t o 0 . 5 s v (hanzlick 1983). and assuming that three quarters of this current continues t o row to the north and the remaining goes round spitsbergen. we found from ( 4 ) that the fresh water formation rate in the region of ourohservation is 1 2 0 krn'/year. moreover. some fresh water appears to be formed to the north. but according to o u r data it is not possible to estimate the complete a m o u n t . according t o ouadfawl et al. (1987) and untersteiner ( i y x x ) . an unknown part of this water is thought to recirculate and join the east greenland current recently we invcstigated the interaction between the eastern branch of the wsc and the sea ice to the north of spitsbergen. direct measurements. carried o u t during the k/v otto schmidt cruise in april 19'91 to the east of the ice margin in this region. gave an estimated ice melting rate of about ycm/day. t h e maximum melting rate was not over the warmest a!lantic water. hut rather ovcr the continental slope, being more than that reported above. w e suggest this fact to be possibly con nected with the recent results by padman & dillon (1991) who investigated water mass modification n e a r the yermak plateau and found i t to be linked t o current-topography interactions. a detailed discussion of such a mechanism is beyond the scope of this study a n d will be presented in o u r next paper. we would like to mention. however. that the reaion north of spitshergen probably corresponds bctter with untersteinder's (1988) "ice wcdge" description than with the northeastern area of the fram strait. i n o u r opinion, the latter may be associated with the existence of a mechanism that appears to neutralize the suppression of the heat flux from the ocean upwards despite the rapid ice melting and when a strong vertical mixing by surface waves (evidently the main mechanism of vertical heat transfer in the northeastern part of the fram strait) is absent. as is well-known the storage of fresh water in the arctic ocean represents o n e of the major uncertainties in under \tanding hoth arctic and global climate (aagaard & carmack 1989). thus. the importance of the problem demands further observational and modelling efforts to improve o u r knowledge of air-ice-sea interactions in the frain strait. ackrio~,lengernerif.\. we would like t o acknowledge two anonymous reviewers for their valuable commcnts on a n early draft of this p a p e r . we a r e also grateful for the help provided by the officers a n d research scientists aboard the ice-breaker r v otto s c h m i i y i references aagaard. k . a , . darnall, c . , foldvik, a , , & terrcscn. t. 1985: fram strait current measurements. 198619x5, joint data report. bergen. norway. 85 p p . aagaard. k . a . & carmack, e . c. 1989: the role of sea ice and other fresh water in the arctic circulation. j . geophys. res. y4 (c/o). 14485-14498. hanzlick. d . j . 1983: t h e west spitsbergen current: transport, forcing and variability. p h . d . thesis. univcrsity of wash ington. seattle. johannesscn. j . a , . johannessen. 0. m . , svendsen. e.. shuch man. r . . manley. t . . campbell. w . j . , josherger. e. g . . sandvcn. s . . gascard, j . c . , olaussen. t.. davidsoii. k. & van leer. j . 19x7: mesoscale eddies in the fram strait marginal ice zone during the 1983 and 1984 marginal ice zone experiment. j . geophys. res 92 (c7). 67546772, josberger. e . g . 1987: b o t t o m ablation a n d heat transfer coef ficients from the 1983 marginal ice zone expcrinicnts. j . geuph,vs. res. 92 (c7), 7012-7016. makshtas. a . p.. tikmachev, v. f. & ivanov. b . v. 1989: energy exchange between the atmosphere and the underlying surface in the marginal ice zone. workshop proceedings 'regional and mezoscale modelling of ice cover oceans'. n r s c conference r e p o r f n 3 , ix6190. padman, l . & dillon. t . m . 1991: turbulent mixing near the yermak plateau during the coordinated eastern arctic experiment. j . g e o p h y s . res. y6(cll). 476f4782. k.-p. 1987: large-scale oceanography in fram strait during the 1984 marginal ice z o n e experiment. j . geophys. res. 92 (c7). 67194728. untersteiner. n. 1988: on the ice and heat balance in frdm strait. 1. g e o p h y s . r e s . 93 (cl), 521-533. vinje. t. & finnekisa, 0. 1986: t h e ice transport through the fram strait. norsk polarinsf. skrifrer 186. 39 pp. ouadfasel, d. j . , gascard. j.-c. & koltermann a preliminary survey of the terrestrial arthropods of the rosenthal islands, antarctica research note a preliminary survey of the terrestrial arthropods of the rosenthal islands, antarctica j.d. gantz a, drew e. spacht b & richard e. leea adepartment of biology, miami university, oxford, oh, usa; bdepartment of evolution, ecology and organismal biology, ohio state university, columbus, oh, usa abstract the rosenthal islands lie along the western edge of the antarctic peninsula. they are largely inaccessible and the few research projects in the area have focused on seabird colonies, so nothing has been known about the arthropod fauna on these islands. we conducted a preliminary survey of the arthropods associated with large penguin colonies. we identified two species of collembola (cryptopygus antarcticus and friesea grisea), four species of mites (alaskozetes antarcticus, hydrogamasellus racovitzai, tectopenthalodes villosus and rhagidia sp.) and one insect (belgica antarctica). the mite a. antarcticus and the collembolan c. antarcticus were common in large aggregations at our collecting sites and were occasionally observed on the surface of penguin guano without vegetative cover. the insect, a chironomid midge, was less common and found only in vegetated areas. keywords antarctic peninsula; maritime antarctic; collembola; mites; belgica antarctica introduction the purpose of this survey was to examine arthropod diversity and abundance in the rosenthal islands, which lie within the antarctic specially managed area no. 7 and are under consideration for designation as an antarctic specially protected area. the rosenthal islands (64°35’s, 64°16ʹw) lie on the western edge of the antarctic peninsula, along the west coast of anvers island (fig. 1). despite their proximity to palmer station, the rosenthal islands remain largely inaccessible for scientific study on account of incomplete bathymetry records, many shoals and large swells that make boating difficult. as a result, nothing was known about the arthropods of these islands prior to this survey. because the rosenthal islands are near palmer station (64°46’s, 64°03ʹw), where the flora and fauna are well characterized, one might assume that the terrestrial arthropod fauna is similar; however, climatic conditions may be quite different between the two locations. whereas the area around palmer station is sheltered by cape monaco from the swell and storms coming from the drake passage, the rosenthal islands are not protected, are geographically closer to the open ocean where storms circulate along the antarctic circumpolar current (hoskins & hodges 2005) and, as a result, likely experience more wind and precipitation. while there are no climate data available for the rosenthal islands to test this assertion, snow cover and depth during our survey was more extensive than it was near palmer station at the same time. indeed, only a small fraction of the land on the islands surveyed in this study was free of snow and ice. further, extensive snow cover, along with seabird activity, likely affect the diversity and abundance of arthropod species in the rosenthal islands through their influence on vegetative growth. nearly all the exposed land on the islands included in this survey is used by nesting seabirds (w.r. fraser, pers. comm. 2017), which can prevent plant growth through trampling and the toxicity of guano (ryan & watkins 1989; sinclair et al. 2006; smykla et al. 2007; schaefer et al. 2017). virtually all the islands near palmer station support moss beds, the terrestrial alga prasiola crispa (lightfoot) kützing 1843 and antarctic hair grass deschampsia antarctica e. desv. (strong 1967), the vegetation we found in the rosenthal islands was largely restricted to steep ridges and small, isolated rock outcroppings without nesting seabirds. what is known about the vegetation on the islands that we did not visit was gleaned from satellite imagery (c. harris, pers. comm. 2017). gerlache island, the largest of the rosenthal group, is nearly 100% glaciated; the other islands are not glaciated and many are at least partially vegetated. though some antarctic arthropods can live in habitats without vegetation (gressitt 1967; strong 1967; sinclair 2001), vegetative cover mitigates problems with water availability, which is the limiting factor for habitat selection on the antarctic peninsula (janetschek 1970; kennedy 1993; convey et al. 2003; contact j.d. gantz gantzjd@miamioh.edu department of biology, miami university, 700 e. high st, oxford, oh 45056, usa polar research 2018, vol. 37, 1500266 https://doi.org/10.1080/17518369.2018.1500266 © 2018 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0003-3847-6031 http://orcid.org/0000-0002-3651-114x http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2018.1500266&domain=pdf hayward et al. 2004). as such, vegetative cover is an important factor influencing arthropod diversity and abundance in the maritime antarctic (worland & block 1986; ryan & watkins 1989). the extensiveness of our survey was severely limited by time and circumstance. our ship’s schedule gave us an 18 h window in which to work. poor weather reduced that window to just 8 h, mostly during the late evening and extended twilight hours of the polar summer. further, the only three islands we were able to visit support penguin colonies, whereas most of the remaining 40 or more islands that make up the rosenthal group do not. thus, this note represents only a limited survey of arthropods found on islands heavily used by penguins. materials and methods the rosenthal islands are located about 21 km northwest of palmer station, along the western coast of anvers island (fig. 1). gps locations for each of the islands surveyed are: island 1: s 64.59079 w 064.24715; island 2: s 64.60035 w 064.21499; and island 3: s 64.60297 w 064.21044. the survey was conducted on islands 1, 2 and 3 on 13 december 2016. surveys were restricted to spotchecking habitats that seemed most likely to support arthropods. these locations generally fit into one of two categories: along the edge of seabird colonies (where special attention was paid to ornithogenic soil under rocks), and areas with moss and p. crispa that were unused by or inaccessible to nesting seabirds. time constraints prevented us from surveying intertidal zones, which are a preferred habitat of at least one species of mite, rhombognathus gressitti newell, found in the maritime antarctic (strong 1967). we used aspirators to collect at least five individuals from each distinct species observed in the field. we also sampled large aggregations by collecting substrate from within the aggregation. these samples were returned to our laboratory at palmer station, figure 1. map of the rosenthal islands. gps waypoints for the three islands surveyed: island 1: s 64.59079, w 064.24715; island 2: s 64.60035, w 064.21499; island 3: s 64.60297w, 064.21044. 2 j.d. gantz et al. where arthropods were separated from the substrate using a modified berlese extraction (kawarasaki et al. 2013). substrate was placed on screens above metal trays filled with ice water. heat lamps were then placed above the screens and, as the substrate dried, the arthropods moved downward, falling through the screen into the ice water. following extraction, stereoscopic microscopes were used to help with identification. sample collection was not standardized and cannot be used to estimate abundance. results collembola collembola were present in numerous aggregations of thousands of adults and sub-adults on each of the three islands (table 1). cryptopygus antarcticus willem, 1901 predominated in these aggregations, though friesea grisea schaffer, 1891 was present in smaller numbers. aggregations were found in mosses and p. crispa, under rocks, and even on the surface of guano in active penguin colonies where no vegetation was present. mites mites were also abundant at our collecting sites, with alaskozetes antarcticus michael, 1903 as the dominant species. this common mite was present at all of our sample sites, including in penguin guano without vegetation (table 1). other mites – hydrogamasellus racovitzai trouessart, 1903, tectopenthalodes villosus trouessart, 1902, and rhagidia sp. (either r. gerlachei or r. leechi) – were only found on islands 2 and 3 and where moss or p. crispa were present. insects the chironomid midge, belgica antarctica jacobs, 1900 is abundant near palmer station and is the only insect found in the area (strong 1967). we observed midge larvae in modest numbers (fewer than 100 in each location) in one location each on islands 2 and 3 (table 1). larvae were only found in moss and p. crispa. the collection site on island 2 was an abandoned section of a penguin colony, about 10 m × 5 m in size. it is unclear how long this area was unused, though vegetation was sparse and mainly restricted to sheltered spaces among rocks, suggesting that the substrate remained too toxic to support much vegetation. the site on island 3 was on a cliff face about 10 m high on the leeward side of the island that was too steep for seabirds to use for nesting. moss and p. crispa grew on small ledges, usually less than 15 cm wide, across the cliff face. every other species of arthropod we identified was also present in both of these locations. discussion the results of our survey indicate that some of the arthropods commonly found on the sheltered and vegetated islands around palmer station also thrive in the harsher conditions of the rosenthal islands. indeed, the two most abundant species in the maritime antarctic (tilbrook 1967; block & convey 1995; hogg & stevens 2002) occurred in aggregations of thousands of individuals. though the collembolan c. antarcticus and the mite a. antarcticus were abundant, their distribution was patchy and there were no obvious reasons for their presence or absence in many of the survey sites. this uneven distribution might be explained by clumping due to social factors, rather than limitations of seemingly identical microhabitats (joosse & groen 1970; booth & usher 1984; usher & booth 1986). additionally, the variety of habitats occupied by c. antarcticus and a. antarcticus supports the idea that these are generalists that tolerate a wide variety of environmental insults (richard et al. 1994). low temperature, particularly, does not appear to be a limiting factor for survival in the rosenthal islands because these, and other, species table 1. the islands and habitat types where each species of arthropod was identified in the rosenthal islands. n/a denotes the absence of that habitat type found on the island. island substrate type acari collembola insecta 1 ornithogenic soil, no vegetation a. antarcticus c. antarcticus f. grisea vegetated n/a n/a n/a 2 ornithogenic soil, no vegetation a. antarcticus h. racovitzai c. antarcticus f. grisea vegetated a. antarcticus h. racovitzai t. villosus c. antarcticus f. grisea b. antarctica 3 ornithogenic soil, no vegetation a. antarcticus h. racovitzai c. antarcticus f. grisea vegetated a. antarcticus h. racovitzai t. villosus rhagidia sp. c. antarcticus f. grisea b. antarctica polar research 3 are widely distributed in colder areas further south along the antarctic peninsula (convey & smith 1997; convey 1998; stevens & hogg 2002). interestingly, c. antarcticus, and a. antarcticus, were both common on the surface of penguin guano in active parts of the penguin colonies. while it is not uncommon to find these species in similar locations elsewhere (strong 1967), they are typically under rocks and, despite extensive collecting, we have never observed large aggregations on the surface of guano at palmer station. it is possible that the timing of our survey could explain this behaviour. the surveys were conducted from approximately 18:00 until 02:00 (local time), which includes a few hours of twilight. perhaps the observed behaviour is common during the overnight hours when we would not normally be out collecting to see it; however, this seems unlikely because many aggregations were noted on penguin guano early in the survey, well before sunset. instead, since arthropods select habitats under rocks to mitigate water stress (strong 1967), this behaviour was more likely the result of high relative humidity and moisture content in the substrate resulting from recent precipitation, reducing or eliminating the need for water-conserving behaviour. with the exception of c. antarcticus, and a. antarcticus, the other arthropods we identified in this study were restricted to habitats with vegetation. this could be because vegetative cover can help retain water and water availability, not cold, is the limiting factor for arthropods in the maritime antarctic (kennedy 1993; convey et al. 2003; hayward et al. 2004). cryptopygus antarcticus and a. antarcticus may behaviourally overcome the limitations presented by hydric stress in non-vegetated sites by seeking moist refuges during periods of hydric stress (hayward et al. 2001; hayward et al. 2004) and forming aggregations, which enhances resistance to desiccation (benoit et al. 2008). our preliminary results show that the arthropod diversity of the rosenthal islands is similar to that of palmer station. even so, we observed unusual habitat usage by c. antarcticus, and a. antarcticus, as both species were abundant in areas without vegetative cover, and were struck by how different these islands were from those close to palmer station. acknowledgements the authors would like to thank colin harris and katharina lorenz of environmental research and assessment for contributing the map in fig. 1. we would also like to thank the support staff at palmer station, in particular the small boat operations team, for their hard work and assistance as well as the captain and crew of the laurence m. gould, who provided logistic support and expertly coordinated the field visit. disclosure statement no potential conflict of interest was reported by the authors. funding this research was supported by us national science foundation grant no. plr 1341385. orcid j.d. gantz http://orcid.org/0000-0003-3847-6031 drew e. spacht http://orcid.org/0000-0002-3651-114x references benoit j.b., yoder j.a., lopez-martinez g., elnitsky m.a., lee r.e. & denlinger d.l. 2008. adaptations for the maintenance of water balance by three species of antarctic mites. polar biology 31, 539–547. block w. & convey p. 1995. the biology, life cycle and ecophysiology of the antarctic mite alaskozetes antarcticus. journal of zoology 236, 431–449. booth r.g. & usher m.b. 1984. arthropod communities in a maritime antarctic moss–turf habitat: effects of the physical and chemical environment. the journal of animal ecology 53, 879–893. convey p. 1998. latitudinal variation in allocation to reproduction by the antarctic oribatid mite, alaskozetes antarcticus. applied soil ecology 9, 93–99. convey p., block w. & peat h.j. 2003. soil arthropods as indicators of water stress in antarctic terrestrial habitats? global change biology 9, 1718–1730. convey p. & smith r.i.l. 1997. the terrestrial arthropod fauna and its habitats in northern marguerite bay and alexander island, maritime antarctic. antarctic science 9, 12–26. gressitt j.l. 1967. notes on arthropod populations in the antarctic peninsula—south shetland islands—south orkney islands area. in j.l. gressitt (ed.): entomology of antarctica. pp. 373–391. washington, d.c.: american geophysical union. hayward s.a.l., bale j.s., worland m.r. & convey p. 2001. influence of temperature on the hygropreference of the collembolan, cryptopygus antarcticus, and the mite, alaskozetes antarcticus from the maritime antarctic. journal of insect physiology 47, 11–18. hayward s.a.l., worland m.r., convey p. & bale j.s. 2004. habitat moisture availability and the local distribution of the antarctic collembola cryptopygus antarcticus and friesea grisea. soil biology and biochemistry 36, 927–934. hogg i.d. & stevens m.i. 2002. soil fauna of antarctic coastal landscapes. in l. beyers & m. bölter (eds.): geoecology of antarctic ice-free coastal landscapes. pp. 265–280. berlin: springer. hoskins b.j. & hodges k.i. 2005. a new perspective on southern hemisphere storm tracks. journal of climate 18, 4108–4129. janetschek h. 1970. environments and ecology of terrestrial arthropods in the high antarctic. in m.w. holdgate (ed.): antarctic ecology. vol. 2. pp. 871–885. new york: academic press. joosse e.n. & groen j.b. 1970. relationship between saturation deficit and the survival and locomotory 4 j.d. gantz et al. activity of surface dwelling collembola. entomologia experimentalis et applicata 13, 229–235. kawarasaki y., teets n.m., denlinger d.l. & lee r.e. 2013. the protective effect of rapid cold-hardening develops more quickly in frozen versus supercooled larvae of the antarctic midge, belgica antarctica. journal of experimental biology 216, 3937–3945. kennedy a.d. 1993. water as a limiting factor in the antarctic terrestrial environment: a biogeographical synthesis. arctic and alpine research 25, 308–315. richard k.j., convey p. & block w. 1994. the terrestrial arthropod fauna of the byers peninsula, livingston island, south shetland islands. polar biology 14, 371– 379. ryan p.g. & watkins b.p. 1989. the influence of physical factors and ornithogenic products on plant and arthropod abundance at an inland nunatak group in antarctica. polar biology 10, 151–160. schaefer c.e., pereira t.t., almeida i.c., michel r.f., corrêa g.r., figueiredo l.p. & ker j.c. 2017. penguin activity modify the thermal regime of active layer in antarctica: a case study from hope bay. catena 149, 582–591. sinclair b.j. 2001. on the distribution of terrestrial invertebrates at cape bird, ross island, antarctica. polar biology 24, 394–400. sinclair b.j., scott m.b., klok c.j., terblanche j.s., marshall d.j., reyers b. & chown s.l. 2006. determinants of terrestrial arthropod community composition at cape hallett, antarctica. antarctic science 18, 303–312. smykla j., wołek j. & barcikowski a. 2007. zonation of vegetation related to penguin rookeries on king george island, maritime antarctic. arctic, antarctic, and alpine research 39, 143–151. stevens m.i. & hogg i.d. 2002. expanded distributional records of collembola and acari in southern victoria land, antarctica. pedobiologia 46, 485–495. strong j. 1967. ecology of terrestrial arthropods at palmer station, antarctic peninsula. in j.l. gressitt (ed.): entomology of antarctica. pp. 357–371. washington, d.c.: american geophysical union. tilbrook p.j. 1967. the terrestrial invertebrate fauna of the maritime antarctic. philosophicaltransactions of the royal society of london, series b, biological sciences 252, 261–278. usher m.b. & booth r.g. 1986. arthropod communities in a maritime antarctic moss–turf habitat: multiple scales of pattern in the mites and collembola. the journal of animal ecology 55, 155–170. worland m.r. & block w. 1986. survival and water loss in some antarctic arthropods. journal of insect physiology 32, 579–584. polar research 5 abstract introduction materials and methods results collembola mites insects discussion acknowledgements disclosure statement funding references spatial and temporal variability in the responses of arctic terrestrial ecosystems to environmental change terry v. callaghan, malcolm c. press, john a. lee, david l. robinson & clive w. anderson this paper compares the responses of two contrasting arctic ecosystems to climate change simulations: a polar semi-desert (in svalbard) and a dwarf shrub heath (at abisko, northern sweden). these ecosystems are located close to the northernand southernmost extremes of the arctic region, respectively. impacts of simulated climatic changes were determined through factorial perturbation experiments, where growing season temperature, nutrient availability and water supply were manipulated. the results are compared with the impact of interannual variation in climate on the growth of a keystone moss species, hylocoinium splendens, from the wider circumpolar area. the perturbation studies revealed that current interannual variability in temperature and the temperate tolerance of many species may exceed predicted changes in mean summer temperature over the next century. arctic ecosystems differed in their responses to environmental manipulations, with the structure of the dwarf shrub heath being affected through shifts in competitive hierarchy, potentially leading to lower biodiversity, and the polar semi-desert being affected through invasion, potentially leading to higher diversity. h. splendeizs showed negative responses to perturbation at the sub-arctic site, in contrast to the positive relationship between temperature and growth observed in the natural environment. this apparent discrepancy may result from: (i) artefacts arising from the perturbations, such as lower atmospheric relative humidity; (ii) non-equilibrium responses during the relatively short-term perturbation studies and/or (iii) ecotypic variation in the moss population. thus, caution should be employed when extrapolating from perturbations studies to both longer time-scales and different ecosystems within the arctic. t. v. callaghan. the royal swedish academy oj’ sciences’ abisko scientific research station, se-981 07 abisko, sweden, and the shefield centre f o r arctic ecology, dept. of animal and plant sciences, shefield university, 26 taptonville road, shefield s l o 5br, u k ; m . c. press & j. a . lee, dept. of animal and plant sciences, sheffield university, alfred denny building, western bank, shefield sio 2tn, u k ; d. l. robinson & c. w. anderson, dept. of probability arid statistics, shefield university. western bank, shefield sio 2tn, uk. introduction climate change is a global concern that is amplified in the arctic since predicted increases in temperature are greater than for lower latitudes (cattle & crossley 1995; weller 1999). permafrost, soils and biota are also likely to be particularly sensitive to change (chapin, jefferies el al. 1992). plants, for example, have long life cycles with little possibility of adapta tion. generally low and sporadically successful recruitment from sexual reproduction, and an existing burden of multiple stresses such as low nutrient availability, herbivory, and harsh climate (jonasson et al. in press). changes in arctic ecosystems could have important consequences for the sustenance and cultural identity of northern human populations, the maintenance of a rich and characteristic wildlife, and the earth’s atmospheric circulation via albedo effects and by the sequestering of atmospheric c 0 2 in extensive organic soils. callaghan et al. 1999: p a l m research 18(2), 191-197 191 although global circulation models generally predict that the greatest warming will occur at high latitudes in the winter, it is clear that climatic changes will vary regionally. indeed, recent changes have shown both cooling and warming in different areas of the arctic: south and mid-west greenland has cooled by 1°c per decade whereas continental parts of alaska and siberia have warmed by the same extent over the past 30 years (walsh, quoted in weller in press). other areas, such as arctic europe, have warmed only moderately, and then mainly during the present decade. it is therefore, dangerous to generalize future climatic trends for the whole circum-arctic region. moreover, ecosystems vary considerably in structure and function throughout the region: they vary from open forest tundra at the southern border of the arctic to polar desert in the far north, and from shrub communities at the altitudinal tree line to fell field in the alpine zone. communities vary along continental gra dients from moss-dominated communities in oceanic areas to relict tundra steppe communities in interior alaska and siberia. and plant communities vary from productive closed and relatively tall vegetation of woody species to open communities dominated by cryptogams with low productivity. such different arctic ecosystems would be expected to respond differently to even the same change in climate. climate also varies greatly with time. die1 variations around mid-summer and mid-winter are less pronounced than at lower latitudes but the seasonal variation is dramatic, with a snow free growing season that seldom exceeds three months (weller in press). at the annual scale, weather conditions vary between years and the temperatures of some months (often in spring and autumn) may vary markedly. in addition, extreme events occur. it is likely that trends of ecosystem responses in time will not be linear or follow a smooth trend but are likely to be punctuated with stochastic extreme events that may reinforce trends of ecosystem change or even negate them. this paper focuses on a comparison between the responses of two contrasting arctic ecosystems to climate change simulations. these ecosystems are located close to the northernmost and southern most extremes of the arctic region. transient responses of these ecosystems to simulated climatic changes will be compared with equili brium responses of a keystone plant species to climate over a longer period of time and from the wider circumpolar area. approaches two basic approaches are combined in this study. one is to perturb ecosystems by simulating some of the components of predicted climate change. this approach has been applied to a closed dwarf shrub heath community in abisko in sub-arctic swedish lapland (68"21'n, 18'49'e) and a high arctic polar semi-desert community in svalbard (78"56'n, 11'50%) in which only about 40% of the ground was covered by vegetation. full site descriptions are given in wookey et al. (1993). the components of predicted climate change that were manipulated are (1) summer air temperature, which was increased by between 2.7 (abisko) and 3.5"c (svalbard) using open top plastic chambers (see wookey et al. 1993 and parsons et al. 1994 for details); (2) increased nutrient availability (10, 10 and 12.6 g m-'yr-' of n, p and k, respectively, at the lapland site, and 5.0, 5.0 and 6.3 g m-* yr' of n, p and k, respectively, at the svalbard site) to explore the possibility of increases in microbial activity induced by soil warming and nutrient release, in addition to increased atmospheric nitrogen deposition; (3) increased summer pre cipitation (50% in both lapland and svalbard). the experiments, still in progress, were estab lished in 1991 and results presented here are for the first five years. while this approach allows direct simulations of climate change to be made, it also gives insights in to the various current environmental constraints on ecosystems because the manipulations can be performed independently of each other as well as factorially. also, the controls of the experiment serve as useful monitoring plots for natural interannual weather variations (henry & molau 1997). however, a constraint of the experimental approach is that the manipulations are confined to quite small plots (1.5 m x 1.5 m) rather than landscapes, and changes that occur are detected in real time over relatively short periods. the second approach discussed here is the retrospective analysis of plant growth (callaghan, carlsson & tyler 1989; callaghan, carlsson, sonesson et al. 1997). some widespread arctic species are long-lived and past growth can be identified and measured. this allows statistical 192 spatial and temporal variability in the responses of arctic terrestrial ecosystems to environmental change f i g . 1. changes in cover of the most abundant higher plants and mosses and lichens at the polar semi-desert site (svalbard) related to increased nutrient availability (data from 25 robinson et al. 1998). 30 20 l 15 t 8 10 5 0 x cover of species receiving nutrients relative to controls 1 x . .. / 0 i.. 1991 models to be constructed of climate-driven growth in ways analogous to dendrochonology (call aghan, carlsson & tyler 1989). some species have records of growth that go back 30 years while even the moss hylocomium splendens can contain growth records of more than 15 years (callaghan, carlsson, sonesson et al. 1997). when samples are collected from different habitats, from different / i / + -t +t treatments l r=0.94* + + , i i i -1 0 5 0 5 mean annual temperature ("c) fig. 2. (a) growth rate and (b) maximum annual growth increment in hyloconiiurrt splerzdens in relation to mean annual temperature at several arctic sites (from callaghan. carlsson, sonesson et al. 1997). (c) the effect of temperature elevation (+t) on the dry wt. of the moss is also shown (from potter et al. 1995). 1993 year 1995 regions, or even from different historic periods, a greater understanding of plant responses to climate variation in space and time can be gained than with field manipulation experiments, although relation ships between past growth and climate must remain correlative rather than causal. together, the two approaches give a powerful insight into the complexity and probable causes of plant responses to climatic variations. variation in space of arctic ecosystems' responses to climate change responses of individual plant species to increased temperature were greater at the colder site, svalbard, and were particularly pronounced in developmental processes such as flowering, re productive development and leaf area expansion (wookey et al. 1993). enhanced seed production and viability in the open vegetation of the high arctic is particularly important for the process of colonization and closure of vegetation cover (see below). nutrient addition had fewer and smaller effects than increased temperature on reproductive development at the svalbard site but stimulated vegetative growth, particularly of the dominant species dryas octopetala and resulted initially in an increase in cover (fig. 1) (robinson 1997; robinson et al. 1998). an increase in total plant cover, particularly in relation to nutrient addition, was also achieved by colonization of mosses and callaghan et al. 1999: polar research 18(2), 191-197 193 table i. potential rate of colonization of a polar semi-desert site in svalbard by dryas octopernla. see text for more details assumptions 0 there will be an increase of available nutrients similar to those given in the environmental manipulation experiment, 0 no extreme weather event will occur. 0 the spread of d i y u will be continuous and will occur at a maxima1 rate. 0 there will be a linear increase in cover with time. 0 there will be no competition from co-occurring or immigrating species. 0 there will be no preferred directionality of growth. starting variables measured cover of d r y s at start available space (littedorganic detritus, dead plant parts and bare ground) maximum, measured annual rate of increase calculated rate of colonization number of years required to complete colonization and close the canopy linear, annual growth (mm) 7.8% 73.4% 5.8% 12 29 immigrant higher plants, which had characteristics of nitrogen-rich bird cliff communities (robinson et al. 1998). at the sub-arctic abisko site, the four dominant dwarf‘ shrubs showed individualistic responses to temperature increases (parsons et al. 1994) but their responses to nutrient addition were even greater. the grass calamagrostis lapponica in creased its dominance at the abisko site (press et al. 1998) through an 18-fold increase in abundance and an increase in height that elevated the canopy by 86%. biomass at the site increased in relation to increased temperature and nutrients. mosses at this site also showed individualistic responses to treatments: hylocomium splendens showed re duced growth due to increased temperature or increased nutrients (fig. 2 ) (potter et al. 1995; press et al. 1998), while polytrichum commune increased its growth when nutrients were added. overall, therefore, the sites mainly differed in that increased nutrients and temperature led to an increased occupation of available space and an increased biodiversity at the polar semi-desert site. in contrast, these treatments led to an increase in height, change in dominance and a decrease in biodiversity at the sub-arctic heath site where the canopy was already closed at the start of the experiments. the increase in the cover of dryas receiving nutrients and temperature enhancement between 1991 and 1993 suggests that under conditions of uniform warming, the sparse vegetation of the polar semi-desert community could close, with important implications for increased biomass and carbon storage. making the assumptions outlined in table 1, it is possible to calculate that dryas could close its community within 12 years. however, many of these assumptions are unrea listic: nutrient availability is never likely to be as high as the experimental level; extreme weather events are likely to occur (see next section); an exponential increase in cover with time is more realistic than a linear trend; co-occurring and immigrant species may compete for space; and directionality of growth favours recolonization of dead matter, rather than bare ground, and exten sion along slopes (robinson 1997). when the actual rate of colonization of dryas was modelled using observed patches of dryas and rates of increase in cover measured for the experimental treatments, it was found that dryas grew preferentially onto dead patches rather than onto bare ground (robinson 1997). it also grew across a slope, rather than up or down (figs. 3a, b), and over 80% of patches grew only 1 cm per year or less, with an exceptional maximum rate of radial growth of 4 cm per year (fig. 3c). overall, the mean rate of growth was 0.86 cm per year. variation in time of arctic ecosystems’ responses to climate change during a period of natural or experimental warming, the response of a given species occurs over a great range of time scales. these range from seconds, when photosynthesis responds to chan ging cloud conditions; through hours, when flowers track the sun’s movements; through months, when seasonal changes in leaf develop 194 spatial and temporal variability in the responses of arctic terrestrial ecosystems to environmental change 9 2 8 ). 7 ? 6 !! 4 ; 5 3 2 1 0-l w .. ............. e i i i i i l l 1 0 45 90 135 180 2 2 5 270 315 360 w n e s w direction (4 distance travelled 0.86 cmlyear c m per 5 years fig. 3 . (a) circular histogram and (b) linear histogram showing directional growth and (c) rate of growth of dvyns octopetnla clones from the polar semi-desert site in svalbard (modified from robinson 1997). ment, reproduction and resource storage occur; to years, when life history parameters respond; and longer, when adaptation might occur. although each of these processes has its own significance, it is changes in plant distribution and bio diversity that are particularly important integrative measures of response. changes in productivity, while important in terms of ecosystem function. have a more limited range of response options. table 2. characteristics of an extreme weather event and its impacts on the growth of dryas octopefala at a polar semi desert site in svalbard (from robinson et al. 1998). weather characteristics november weather 1961-1996 mean 1993 temperature "c -7.0 -2.8 precipitation (mm) 69 230 percent cover changes of living and dead dryas with (+f) and without (-f) nutrient addition. p is significance level for living and dead matter at p 5 0.01** and p c 0.001***; ns is non-significant differences. 1991 1993 1995 living matter + f 14.5 26.1 14.5 living matter -f 14.6 14.6 21.6 p ns dead matter + f 7.3 2.6 19.4 dead matter -f 8.9 4.2 11.3 p ns ns ns *** ** during a period of warming, it is unlikely that ecosystems will reach an equilibrium stage or even keep pace with the changing environment. this applies particularly in the arctic where plants are long-lived and many have specific mechanisms to buffer environmental changes such as interannual variations in weather (callaghan, carlsson & tyler 1989). recorded responses of vegetation to experimental warming in the field must be seen, therefore, as a particular stage in a longer series of changes. thus, in warming experiments in alaska (chapin, shaver et al. 1995), alpine lapland (molau & alatalo 1998), and lowland lapland (jonasson 1992; parsons et al. 1995; press et al. 1998), ecosystem warming in the first year led to a change in dominance favouring graminoid species. however, after a decade or more in alaska, dwarf birch increased its dominance. in the lowland heath at abisko where polycormic mountain birch predominates, particularly vigorous, perhaps even monocormic trees typical of warmer areas, might be expected to become dominant eventually. natural warming may not follow such smooth trends in time, however. at the polar desert site in svalbard, an exceptionally warm period occurred in november 1993 (table 2 ) . this was associated with exceptionally high precipitation that fell as rain rather than snow. the effect of this was to kill shoots of many species such as dryas (table 2 ) , particularly those individuals that had received fertilizer addition and which remained green much later into autumn (robinson et al. 1998). a result of this extreme event was that dryus cover callaghan et al. 1999: polar research 18(2), 191-197 i95 developed stochastically rather than smoothly over time (fig. 1). such extreme events can, theoreti cally, either enhance a longer trend of increasing vegetation cover in response to warming or, as seen here, negate it. one problem associated with environmental manipulation experiments in the arctic is that it is not feasible to sample all the variation existing within a given landscape or vegetation type, or to sample over a time period long enough for major community reorganizations to occur. as an example, environmental manipulation experi ments in a lowland heath at abisko in lapland showed that mosses were particularly sensitive to manipulations. the moss hylocomium splendens, which is particularly widespread and an important component of many northern ecosystems, showed a decrease in cover (press et al. 1998) and vigour (fig. 2; potter et al. 1995) when temperature or nutrients were increased. this result contrasts with trends of increasing growth rate and size (maxi mum annual dry weight increment) with increas ing temperature observed for populations collected from sites situated along a large annual tempera ture gradient (fig. 2 ; callaghan, carlsson, sones son et al. 1997). hylocomium is clearly found in areas warmer than those induced by the enhanced temperature treatment. indeed, h. splendens is characteristic of some southern boreal forests with mean annual temperatures of about 7°c (gkland 1997) and some even warmer temperate regions. three possible mechanisms might explain this apparent discrepancy. first, experimental warming might have artefacts, such as reducing air moisture, that are particularly important for ectohydric mosses such as hylocomium. however, natural increases in temperature without increases in precipitation might lead to a similar effect. second, experimental warming over five years induced vegetation change only to the stage of dominance by graminoids and associations be tween this moss and dense grass canopies are not typical. over a longer period, the stimulation of a denser forest canopy layer, either deciduous or evergreen coniferous, would be expected to reduce the dominance and density of the grasses below, cool the surface (dyrness et al. 1986; callaghan & jonasson 1995) and open up a new, characteristic niche for hylocomium again. alternatively, or in addition, warming at a much larger landscape scale would include far more niches available for a rearrangement of species associations such that species like hylocomium might be lost from one association and niche, but could move into others. such a suggestion was raised by grime & callaghan (1988). they suggested that environ mental factors producing patch effects such as aspect could play an important role in plant response to climatic warming. thus, species characteristics of south facing slopes at the south ern part of the species range, or local distributional limits, may be relocated to north-facing slopes while only species of north-facing slopes at the northern edge of their range would truly be under threat of loss. in the arctic, small topographical gradients assume great significance for heat gain, soil moisture retention and other abiotic variables. thus, warming may lead to species relocation over small distances under appropriate topographical conditions. the mean annual temperature range naturally experienced by hylocomium is considerable, even though the summer temperatures that the growing moss segments experience might show a smaller range. in the data illustrated in fig. 2 it spans 16°c; including 0kland's populations (0kland 1997), the range exceeds 2vc, from -13°c to +7"c. this range is far greater than the expected increase in temperature over the next century, i.e. between 2 to 4°c in summer (cattle & crossley 1995). although there might be different ecotypes throughout this range, as a species, it is unlikely that hylocomium will be displaced except from the southernmost areas of its distribution. conclusions we still have limited ability to generalize about the impacts of environmental change on arctic terrestrial ecosystems because of the spatial and temporal patterns of environmental change, the responses of ecosystems at various levels of complexity from physiological processes to eco system function and structure, and because of the complex interactions between co-occurring envir onmental change factors. however, the two approaches summarized here suggest that: (i) current interannual variability in summer temperature and the temperature tolerance of many circum-arctic species might override pre dicted changes over the next century. (ii) in closed communities, changes in nutrient availability will affect their structure through 196 spatial and temporal variability in the responses of arctic terrestrial ecosystems to environmental change changes in competitive hierarchy, possibly leading to reduced biodiversity. (iii) major vegetation change in response to temperature is expected at high latitudes and altitudes, i.e. on substrates open to colonization and at the cold tolerance limit of the species. this should lead to increased biodiversity in these locations. acknowledgements. we are grateful to the uk natural environment research council, which supported much of this work (grant gst/02/53 i ) , the eu-basis project (framework iv, grant env4-ct-0637), staff at the abisko scientific research station, the norwegian polar institute and the kings bay kull company for allowing us access to facilities, and past and present members of the sheffield centre for arctic ecology together with members of the department of plant ecology, lund university, for their past and present contributions to the research. references callaghan, t. v., carlsson, b. 8., sonesson, m. & temesvary, a. 1997: between-year variation in climate-related growth of c i r c u d r c t i c populations of the moss hylocomiuni spleiz dens. fnnct. ecol. 11. 157-165, callaghan, t. v., carlsson, b. a. & tyler, n. j. c. 1989: historical records of climate related growth in cassiope tetragona from the arctic. .i. ecol. 77, 823-837. callaghan. t. v. & jonasson, s. 1995: arctic terrestrial ecosystems and environmental change. phil. t r a m r . soc. lond. a 352, 259-276. cattle, h. & crossley, j. 1995: modelling arctic climate change. phil. trans. r. soc. lond. a. 352, 201-213. chapin, f. s. 111, jefferies, r. s., reynolds. g. r., shaver, c. r. & svoboda, j. (eds.) 1992: arctic ecosystems i n a changing climate, an ecophysiological perspective. 469 pp. san diego: academic press. chapin, f. s. 111, shaver, g. r., giblin, a. e., nadelhoffer, k. g. & laundre. j. a. 1995: responses of arctic tundra to experimental and observed changes in climate. ecology 76. 694-711. dyrness, c. t., viereck, l. a. & van cleve, k. 1986: fire in taiga communities of interior alaska. ecol. stud. 57, 74-86. grime, j. p. & callaghan, t. v. 1988: direct and indirect effects of climate change on plant species, ecosystenis and processes of conservation and ameniv inferest. (contract contract report ref. t07020bl). london: dept. of the environment wk). henry, g. h. r. & molau, u. 1997: tundra plants and climate change: the international tundra experiment (itex). global change b i d . 3 (suppl. i ) , 1-9. jonasson. s. 1992: growth responses to fertilization and species removal in tundra related to community structure and clonality. oikos 63, 420-429. jonasson, s., callaghan, t. v., shaver, g. r. & nielsen, l. a. in press: arctic terrestrial ecosystems and ecosystem function. in m. nutall. & t. v. callaghan (eds.): the arctic: its environment, peoples and policy. reading: harwood aca demic publishers. molau, u. & alatalo, j. m. 1998: responses of subarctic-alpine plant communities to simulated environmental change: biodiversity of hryophytes, lichens and vascular plants. ambio 27, 322-329. 0kland. r. h. 1997: population biology of the clonal moss hylocomium splendens in norwegian boreal spruce forests. 111. six-year demographic variation in two areas. lindbergia 22.49-68. parsons, a. n., welker, j . m., wookey, p. a,, press, m. c., callaghan, t. v. & lee, j. a. 1994: growth responses of four sub-arctic dwarf shrubs to simulated environmental change. j . ecol. 82, 307-318. potter, j. a,. press, m. c., callaghan, t. v. & lee, j. a. 1995: growth responses of polytrichum commune hedw. and hylocotnium splendens (hedw.) br. eur. to simulated environmental change. new phytol. 131, 533-541. press, m. c., potter, j. a,, burke, m. j. w., callaghan, t. v. & lee, j. a. 1998: response of a sub-arctic dwarf shrub heath community to simulated environmental change. j . ecol. 86, 3 15-327. robinson, c. h., wookey, p. a., lee, j. a,, callaghan, t. v. & press, m. c. 1998: plant community responses to simulated environmental change at a high arctic polar semi-desert. ecology 79, 856-866. robinson, d. 1997: directional preferences in arctic plant movement. m.sc. thesis, university of sheffield, uk. weller, g. in press: the climate of the arctic. in m. nutall & t. v. callaghan (eds.): the arctic: its environment, peoples and policy. reading: harwood academic publishers. wookey, p., parsons, a,, welker, j. m., potter, j., callaghan, t. v., lee, j. a. & press, m. c. 1993: comparative responses of phenology and reproductive development to simulated environmental change in sub-arctic and high arctic plants. oikos 67,490-502. callaghan et al. 1999: polar research 18(2), 191-197 197 size, age and spawning frequency of landlocked arctic charr salvelinus alpinus (l.) in svartvatnet, svalbard nils gullestad and anders klemetsen gullestad, n. 62 klemetsen, a. 1997. size, age and spawning frequency of landlocked arctic charr salvelinus alpinus (l.) in svartvatnet, svalbard. polar research 16(2), 85-92. this conhihution reports the analysis of a sample of landlocked arctic cham collected with gillnets in svartvatnet, svalbard, 1964. this is the first scientific sample from a landlocked charr population from svalbard. we found a very prominent modal group of large, old and sexually adult fish of both sexes. their length ranged from 15 to 62 cm, but 92% of the fish were longer than 40 cm and 62% of them fell in the 45 to 54 cm interval. the age range was 7 to 31 years, but 93% were 14 years or older and represented 18 year classes. the length-at-age of the charr seemed to increase steadily until they reached the size and age of the modal group. the growth rate decreased sharply after that. the mortality rates within the age span of the modal group seemed to be low. the ages at first spawning for most of the charr in the sample were between 7 and 9 years and spawning cycles of two years were indicated. nils gullestad, noravn. 2, n-3060 svelvik, norway; anders klemetsen, norwegian institute of nature research, department of arctic ecology, storgt. 25, n-9005 trams@, norway. introduction the northernmost european populations of arctic charr are found in the arctic archipelago of svalbard where it is the only permanent fresh water fish. both anadromous and landlocked populations are found (gullestad 1975). there are about 15 anadromous populations and prob ably more than 100 non-anadromous populations (svenning 1993). both occur along the whole latitudinal range of the archipelago and are mostly found along the western and northem coasts. many of the non-anadromous populations are landlocked because their upstream migration is physically blocked. new charr localities are still being officially recorded (hindrum 1994). the fishing pressure on the svalbard charr has increased in recent decades because of increasing tourism and motorised transport. the charr populations are vulnerable to increased exploita tion, and although unexploited populations can still be found, their numbers are decreasing. there is an increasing interest in studying charr in svalbard because it is the only fish species in systems of low diversity and because the charr, even this far north, seem to exhibit large genetic, phenotypic, demographic and life history varia tion (klemetsen et al. 1985; svenning 1993; svenning & borgstrom 1995). in this paper we report the results of analyses of a sample of large arctic charr from a landlocked population in svartvatn, in southern spitsbergen, from 1964. this appears to be the oldest sample from a landlocked charr population on svalbard. it provides valuable information because the popu lation was largely undisturbed by exploitation at that time. characteristic modes of large fish have been found in several populations in the arctic regions, including greenland (sparholt 1985; riget et al. 1986), bjomoya (klemetsen et al. 1985), spits bergen (svenning & borgstrom 1995) and elles mere island, canada (parker & johnson 1991; reist et al. 1995). such modes of large charr typically consist of old and sexually adult fish of both sexes with relatively uniform sizes but highly different ages. their demographic structures seem to be stable if they are unperturbed by exploitation (johnson 1983, 1995). arctic charr populations at high latitudes tend to spawn at intervals of two years or more (johnson 1980). restrictions on growth because of low temperatures, short seasons and low food availability have been postulated as reasons for this tendency. in a well-documented study of the anadromous popu lation of the nauyuk system in arctic canada, dutil (1986) found that postspawners needed at least two summers to recover and build up enough energy reserves to spawn again. for non-migra tory charr at lake h in borup fjord, ellesmere 86 n . gullestad & a. klemetsen island, parker & johnson (1991) found that the frequencies of post-spawners were about 0.1 in females and 0.2 in males. these values may indicate very long intervals between spawnings in the population, and also that males spawn twice as frequently as do females. the 1964 sample from svartvatn provided a good opportunity to test whether this unexploited, landlocked population had a structure that con firmed findings from elsewhere in the arctic. we predicted that there would be a defined mode of large and sexually adult fish with a relatively narrow range of sizes and a wide range of ages. we also predicted that spawning intervals among the large charr of svartvatn would be longer than one year but that males would spawn at shorter intervals than females would. the aim of this study was to test these predictions by describing the size and age structure and analysing the growth pattern, condition factors and spawning frequencies of the sample. materials and methods svartvatnet is an oligotrophic lake situated about 3.5 km from the sea at an elevation of 63 m a.s.1. on the southern side of hornsund, in southwest spitsbergen (fig. 1). the surface area is about 0.8 km'. to the west, the bottom forms a steep gradient and the substrate is dominated by rocks and boulders. to the east, the depth of the lake increases gradually and the bottom substratum is predominantly sand. the upper part of the outlet stream, the lisbetelva, has a gentle slope and several shallow pools. the lower part forms a number of small rapids and waterfalls and drops steeply about 50 m before entering hornsund. the steep rise in the lower part of the stream makes it impassable to ascending fish. the lake is influenced by glacial melt water and is usually open from late july or early august to the end of september. in 1964 the last ice on the lake disappeared on 13 august. a total of 194 charr were caught with nylon gillnets during two rounds of sampling in 1964, 143 on 3-5 august and 52 on 11-13 august. the nets were placed singly or in pairs along the eastern shore of the lake. knot to knot mesh sizes of the nets were 20, 25, 29, 35, 40 and 45 mm. this series catches charr longer than 17 cm fork length with approximately equal efficiency (jen f i g . 1. map of svanvatn in the hornsund area. sw spitsbergen. the hatching indicates the area of gillnet sampling. altitudes in m a.s.1. sen 1984). the same effort was used in both rounds of sampling. one small cham was caught with a handnet in a stream pool close to the outlet. all fish were measured for total length, weighed and sexed. scale samples and otoliths were preserved dry. external colouration and flesh colour were noted. the development of the gonads was scored according to the seven-stage scale of dahl(l943) as modified for male charr by gullestad (1975). fish at stages >i11 were considered to be spawners of that year. otoliths were used for age reading by employ ing the grinding technique of nordeng (1961). the innermost spawning imprint in the otoliths was used to estimate the age at first spawning (nordeng 1961). results the net catches from svartvatnet consisted of arctic cham ranging in length from 15 to 62cm. large fish predominated; 92% of the catch size, age and spawning frequency of landlocked arctic charr 87 50 c] female 0 male not sexed length groups, cm fig. 2 . length distribution of landlocked arctic charr, svartvatn 1984. consisted of fish above 40 cm and 62% of these fell in the 45 to 54cm interval (fig. 2). only six fish in the sample were smaller than 35 cm (table 1). the largest female fish was 5 8 c m long and weighed 1680 g, and the largest male was 62 cm long and weighed 2495 g. most fish were dark green on the back with strong yellow or orange spawning colours on the belly. except for three fish shorter than 30cm that had white-coloured flesh and one large fish with yellowish flesh, all charr in the sample (98%) had red-coloured flesh. the first sample (3-5 august) contained larger fish than the second sample did. there were significantly more fish shorter than 40cm and fewer fish longer than 54cm in the second sampling (2% and 23% fish shorter than 40cm and 19% and 6% longer than 54 cm, respectively, for the two samples; chi-square test, p < 0.001, table 1). significantly more females than males were caught overall (1 12 females, 82 males, chi-square test, p < 0.05). however, males were most table 1. length distribution of charr in two consecutive net catches, svartvatn 1964 length groups, cm <35 35-39 4 m 4 4 5 4 9 5&54 > 5 5 total 4-5 august 1 2 23 41 47 28 142 11-13 august 5 6 5 18 15 3 52 frequent among the very largest fish in the sample: 26 out of 30 fish longer than 55 cm were males (chi-square test, p < 0.001). the fish in the net samples were 7 to 31 years old (fig. 3). the single fish caught by hand from the stream pool was 4 years old. as many as 93% of the fish were 14 years or older, representing 18 year-classes. the bulk of the sample (87%) consisted of 13 consecutive, well-represented year-classes (14-26 years). the females were up to 29 years old and the males up to 31 years old (table 2). the total life span, therefore, did not differ much between the sexes, but there were significantly more males than females among the oldest fish above 26 years (chi-square test, p < 0.01). the sexes showed no important length for pge differences. the growth data were therefore pooled. length for age data indicated a slow but steady growth in the svartvatn cham up to age 13 and a mean length of about 45 cm (fig. 4). after age 13, a marked reduction in growth was evident, but there was appreciable size variation in individual fish within each year-class. the range in length for 22-year-old fish, for instance, was 40 to 59cm. on average, a slight increase in length was indicated among the first six of the dominat ing year-classes. after age 18, no length-at-age increase was apparent. the weight for age data fig 3 age distnbution of 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 landlocked arctic charr, svartvatn 1964 age, years 88 n . gullestad & a. klemetsen table 2. numbers of spawning and nonspawning adult charr of different ages in svartvatn 1964 ~ age classes (years) 1 1 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 total 90 spawners 1 3 4 1 2 3 1 6 4 7 4 1 0 1 6 1 1 55 51.9 nonspawners 2 2 6 3 3 4 2 4 1 3 4 6 4 5 2 51 48.1 males spawners 1 1 3 4 1 4 3 1 1 4 3 1 1 28 34.6 nonspawners 1 1 2 6 5 9 2 4 5 2 5 2 2 3 2 2 5 3 6 5 , 4 showed a similar picture; there was a clear retardation in the average growth after age 13, no average growth after age 18, and a large and highly overlapping size variation in the dominat ing year-classes (fig. 5). the condition of these charr showed a high variation, with fulton q-values from 0.5 to 1.3. most were between 0.7 and 1.0 (fig. 6). all very low values (<0.7) were from large fish. these were predominantly males with unripe gonads, presumably spent fish from the year before. spawning marks in the otoliths were found for 164 (85%) of the fish. the majority of these (83%) matured at 7 to 9 years of age (fig. 7). the lowest age at first spawning was 5 years and the highest 11 years. there was no apparent sex difference in the age of first spawning. the gonad maturation pattern showed that only some of the sexually adult fish were ripening to spawn in 1964. the sample covered 21 successive 70 r year-classes (table 2 ) . the youngest spawning female was 13 years old and the youngest spawning male, 14 years old. above these ages, non-spawners and spawners occurred in most age classes of the sample. the few exceptions to this are presumably the result of stochastic variations because there were few fish in some year-classes. the frequency of female spawners above the age of first spawning was not significantly different from 0.5 (chi-square test, p = 0.75). the fre quency of male spawners above the age of first spawning did differ significantly (p < 0.01) from 0.5 but not from 0.33 (p = 0.80). discussion the lower part of the outlet stream from svartvatn, the lisbetelva, is too steep for fish to fig. 4 . length-at-age for landlocked arctic char, svartvatn 1964. size, age and spawning frequency of landlocked arctic charr 89 2400 2000 2 1600 p, .i= e“ g 1200 . 800 i 13 20 i 1 1 . 1 ~ 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 12 14 16 18 20 22 24 26 28 30 i2 age, years fig. 5. weight-at-age for landlocked arctic charr, svartvatn 1964 ascend. it cannot be ruled out that small fish are occasionally taken downstream past the rapid stretch and out to sea, but these fish would be lost to the population. an anadromous life cycle is therefore not possible in the svartvatn system, and the population is essentially landlocked. the term “landlocked’ is used to distinguish this situation from charr systems that are physically open to anadromous migration but in which the popula tion (or part of it) is nevertheless nonmigratory. the prediction that the svartvatn population would have a major mode of large and old fish comprising many accumulated year-classes was confirmed. as many as 18 year-classes were represented in the 40 to 60 cm size range and 13 of these year-classes made up the bulk of charr in the sample. the overlap in fish size between year classes was extensive. the year-class strength within the major mode showed some variation but no more than could be accounted for by stochastic variation. we assume that the fishing mortality in the years prior to 1964 was very low in svartvatn. personnel from the polish research station at isbjornhavna across hornsund (pers. comm. to n. fig. 6. length-weight relationships of landlocked arctic c h m , svartvatn 1964 graphs for fulton condition factors of 0.7 and 1.0 are shown. 15 20 25 30 35 40 45 50 55 60 total lenqth in crn 90 n . gullestad & a . klemetsen 1 1 " 5 6 7 8 9 age, years lln10 12 fig. 7. age at first spawning for landlocked arctic charr, svartvatn 1964. sexes are pooled. gullestad, 1964) had visited svartvatn, but the fishing pressure had been light. landlocked charr of this size have practically no natural predators on svalbard. therefore, the present sample describes the size and age structure of a pristine charr population in the high arctic with very low mortality rates over a long period of time. in 1991, the governor of svalbard took another sample of charr from svartvatn (nilssen & gulseth 1992). this sample was small and biased because only 40-mm nets were used, but it confirms the presence of a mode of large charr, similar to the results from 1964, nearly 30 years earlier. this supports results from arctic canada that unper turbed arctic charr populations tend to have stable age and size structures over long periods of time (johnson 1983, reist et al. 1995). strikingly similar demographic structures have been found in several populations of landlocked arctic charr in the arctic. in greenland, sparholt (1985) reported a major mode of large charr in the iterlaa lakes with lengths up to 52 cm (one fish of 62 cm) and ages up to 19 years; and riget et al. (1986) found a large mode that peaked at 38 cm and comprised several year-classes of up to 24 years in lake tasersuaq. on ellesmere island (canada), parker & johnson (1991) reported a mode of large fish in lake h, borup fjord, that were 14 to 22 years old and about 30 to 5 0 c m long. lake hazen on ellesmere was found to have an upper mode of large charr that were 30 to 70 cm long, most of which were 11 to 28 years old (reist et al. 1995). one fish was 35 years old, certainly one of the oldest arctic charr known. on svalbard, klemetsen et al. (1985) found a mode of large charr ranging from 29 to 50 cm and from 8 to 25 years in age in ellasjoen, bjornoya, and svenning (1993) found a mode of large cham that ranged from 26 to 56 cni in length and from 16 to 31 years in age in arresjoen, north-west spits bergen. there is some variation in size and age ranges between the populations, but they all have the characteristic mode of large and mature fish of uniform size and varying age. the 1964 sample from svartvatn confirms what seems to be a common pattern in landlocked arctic charr populations in the arctic. many allopatric charr populations with an accumulated mode of large charr also have a dense mode of small but sexually mature charr in the population. bimodality tends to increase with latitude (griffiths 1994). there were no small charr in the present gillnet sample, which is to be expected since the nets used only caught charr above 17 cm effectively. small fish were observed in high densities in pools in the upper part of lisbetelva. these fishes are probably a regular part of the svartvatn population and move into the stream in the summer to find food or to avoid predation, or both. several of the large svartvatn charr had small charr in their stomachs. this may indicate that the population has a bimodal structure that is sustained by cannibalism like in arresjoen (svenning & borgstrom 1995), but this needs confirmation by closer studies. the otoliths indicated that the most common ages at first spawning were 7 to 9 years. only a fraction of the sample had gonads that were ripening for spawning in 1964, but all had the characteristic colours of sexually adult charr. this strongly suggests that the large svartvatn charr did not spawn annually. if the reciprocal of the frequencies of spawners are taken to indicate spawning intervals (parker & johnson 1991), the results may indicate that female svartvatn charr tend, on the average, to spawn every second year while males spawn every third year. this is, however, based on defining all stage i11 fish in early august as non-spawners of the year. this may not always be correct for males. the development of the testes can be difficult to assess in august, and the seasonal development may differ between individual fish. there were 19 stage 111 males in the sample (table 2 ) . if only four of these were in fact going to spawn that size, age and spawning frequency of landlocked arctic charr 91 year, then the ratio of male spawners and non spawners was no longer significantly differen! from 0.5 (chi-square test, p < 0.05). the indi cation that males spawned less frequently than females therefore needs confirmation by a sample taken closer to spawning time, when gonad maturation can be assessed with certainty. we conclude that both sexes of the large charr in svartvatn spawned, on the average, every second year and that the prediction that males spawned at shorter intervals than females was not supported. non-annual spawning has been demonstrated for other charr populations in the arctic, for instance, by gullestad (1973, sparholt (1985) and riget et al. (1986). dutil (1986) found that postspawners in nauyuk lake, in arctic canada, were heavily depleted of somatic energy reserves. these are anadromous fishes that spend nearly two years in freshwater during the spawning run because of the special run-off conditions in the system (johnson 1980). dutil concluded that energetic constraints in arctic environments are the reason for spawning cycles of more than one year in length in arctic charr. this is presumably also the case in svartvatn, which is a low productivity system with a short ice-free season. the low condition factors of several specimens indicate that maturation and spawning takes a heavy toll and that these large charr cannot find enough energy in one short season to be able to spawn annually. johnson (1983) published a classic analysis of single fish stocks in arctic lakes from canada and discusses this in a series of papers (see johnson 1994a,b,c and vanriel & johnson 1995, and references therein). a brief account is given by johnson (1995). johnson concludes that the fish in arctic lakes very often single stocks of arctic charr occupy the dominant position in the ecosystem. the uniformly sized fish of variable age form an establishment that imposes top-down stability on the rest of the system. a steady state in which stochastic environmental variability is absorbed by the population has been reached in these undisturbed, isolated systems. johnson compares this situation to the climax concept in plant ecology. his studies have put undisturbed arctic lakes systems on the agenda as natural history documents of considerable theoretical interest. svartvatn supports the johnson hypoth esis that populations of landlocked arctic charr in arctic lakes form dominant modes of large fish that are stable over a long time if undisturbed. the lake is situated within the south-spitsbergen national park (caw 1994). we hope that the present results will contribute to the establishment of a suitable management regime for the valuable charr population of svartvatn. acknowledgements. we would like to thank the norwegian polar institute for financial assistance and practical help. thanks are also due to field assistant h. p. gullestad. we are grateful to the managing editor, jim reist and an anonymous referee for their useful comments on an earlier version of the manuscript, and to jim reist for his comments on the final version. references conservation of arctic flora and fauna (caw) 1994: the state of protected areas in the circumpolar arctic 1994. directorate of nature management, trondheim. 163 pp. dahl, k. 1943: orret og grretvann. studier og forsgk. oslo. 112 pp. (in norwegian). dutil, j.-d. 1986: energetic constraints and spawning interval in the anadromous arctic charr (salvelinus alpinus). copeia 1986 ( 4 ) , 945-955. griffiths, d . 1994: the size structure of lacustrine arctic charr (pisces: salmonidae) populations. biol. j. linn. soc. 51, 337-357. gullestad, n. 1975: on the biology of char (salmo alpinus l.) in svalbard. i. migratory and non-migratory char in revvatnet, spitsbergen. norsk polarinst. arbok 1973, 125140. hindrum, r. 1994: undersekelser av vassdrag p b spitsbergen i 1994. svalbardreye. report, sysselmannen pd svalbard, longyearbyen. 11 pp. (in norwegian). jensen, j. w. 1984: the selection of arctic charr salvelinus alpinus l. by nylon gillnets. pp. 4 6 3 4 6 9 in johnson, l. & bums, b. l. (eds.): biology o f t h e arctic charr. university of manitoba press, winnipeg. johnson, l. 1980: the arctic charr, salve2inus alpinus. pp. 15-98 in balon, e. k. (ed.): charrs: salmonidfishes of the genus salvelinus. dr. w. junk publishers, the hague. johnson, l. 1983: homeostatic characteristics of single fish stocks in arctic lakes. can. j . fish. aquat. sci. 40, 987-1024. long-term experiments on the stability of ons in previously unexploited lakes. can. j . fish. aquat. sci. 51, 209-225. johnson, l. 1994b: pattem and process in ecological systems: a step in the development of a general ecological theory. can. j. fish. aquat. sci. 51, 226246. johnson, l. 1994c: the far-from-equilibrium ecological hinter lands. pp, 51-103 in patten, b. c. & jgrgensen, s . (eds.): complex ecology: the part-whole relationship in ecosystems. prentice hall, englewood cliffs, n.j. johnson, l. 1995: systems for survival: morals and arctic charr (salvelinus alpinus). nordic j . freshw. res. 71, 9-22. klemetsen, a,, grotnes, p. e., holthe, h. & kristoffersen, k. 1985: bear island charr. rep. inst. freshw. res. drottnin gholm 62, 98-1 19. nilssen, k. j. & gulseth, 0. a. 1992: alder-lengdefordeling og nzringsvalg has arktisk r ~ y e (salvelinus alpinus l.) fanget med 40 mm gam i vann p i svalbard. pp. 63-71 in nilssen k . 92 n . gullestad & a . klemetsen j. (ed.): forvaltningsrelazerte rqyeunders(ke1,rer pb sual bard (frgws). programrapport for perioden 1990-1991. report, universitetet i trondheim. 81 pp. (in norwegian). nordeng, h. 1961: on the biology of char (salmo alpinus l.) in salangen, north norway. i. age and spawning frequency determined from scales and otoliths. nyn mag. zool. 10, 67-123. parker, h. h. & johnson, l. 1991: population structure, ecological segregation and reproduction in non-anadromous arctic charr, salvelinus alpinus (l.), in four unexploited lakes in the canadian high arctic. j . fish b i d . 38, 123-147. reist, j., gyselman, e., babaluk, j., johnson, j. & wissink, r. 1995: evidence for two morphotypes of arctic char (sulvelinus nlpinus (l.)) from lake hazen, ellesmere island, northwest territories, canada. nordic j . freshw. res. 71, 39-10. riget, f. f., nygaard, k. h. & christensen, b. 1986 population structure, ecological segregation, and reproduction in a population of arctic char (saluelinus alpinus) from lake tasersuaq, greenland. can. j . fish. aquat. sci. 43, 985-992. sparholt, h. 1985: the population, survival, growth. reproduc tion and food of arctic charr, salvelinus alpinus (l.). in four unexploited lakes in greenland. j. fish biol. 26, 3 13-330. svenning, m.-a. 1993: life history variations and polyrnorph ism in arctic charr, saluelinus alpinus (l.), on svalbard and in northern norway. dr. scient. thesis, university of tromsg, svenning, m.-a. & borgstrgm, r. 1995: population structure i n landlocked arctic charr. sustained by cannibalism? nordic j . freshw. res. 71, 42-31, vanriel, p. & johnson, l. 1995: action principles as determinants of ecosystem structure: the autonomous lake as a reference system. ecology 76, 1741-1757. 122 pp. reindeer in tundra ecosystems: the challenges of understanding system complexity feodor v. kryazhimskii & alexey n. danilov the resilience of tundra ecosystems is limited, with relatively few key biotic components determining the general pattern of the dynamics of these systems. sustainable use of reindeer pastures, which are natural tundra ecosystems, should take into account interactions within the whole complex of key components. among the most important are the small herbivorous rodents. for example, during peak densities lemmings may reduce above-ground plant biomass by 50-70%. at the same time, rapid turnover of nutrients in the form of significant amounts of potassium, phosphorus and nitrogen that lemmings excrete in urine promotes vascular plant growth. it is concluded that these kinds of studies are essential for the sustainable management of russia’s grazing lands: 1) comparative studies of productivity, biological diversity and structure of plant communities under the different pressures exerted by the main groups of herbivorous animals (reindeer and small rodents), as well as under varying levels of industrial development; 2) studies of the direct and indirect effects of herbivorous mammals on biological turnover and energy flow within the system; 3) studies of the role of industrial contamination on the turnover of nutrients in tundra ecosystems. f. v. kryazhimskii & a. n . danilov, institute of plant and animal ecology, ural division of the russian academy of sciences, 202, 8 marta st., 620144 ekaterinburg, russia. it is widely recognized that the resilience of tundra ecosystems is limited, resulting in low tolerance to many extrinsic pressures. this feature is a product of 1) low productivity of the dominant plant communities, and 2) the simple structure (includ ing species composition, trophic chains and energy allocation pathways) of tundra ecosystems (bol shakov et al. 1993). these characteristics are related to thermal instability of permafrost, the relatively short period of evolution of these ecosystems and severe climatic conditions. as a consequence, a relatively few key biotic compo nents determine the general pattern of biological turnover and, consequently, the whole dynamics of tundra ecosystems. protection and sustainable use of reindeer pastures, which are in fact natural plant commu nities, should not ignore the effects caused by other components of tundra ecosystems in addition to reindeer. moreover, interactions within the whole complex of key components of tundra ecosystems are essential for the long-term, sus tained production of reindeer pastures. among these components, the most important for the vegetative cover are small herbivorous rodents. lemming species (dicrostonyx torquatus and lemmus sibiricus) play the leading role within this group (thompson 1955; tikhomirov 1959; pitelka 1964; chernyavskii & tkachev 1982; tishkov 1985). in this paper we take a brief look at this group to demonstrate the importance of examining reindeer habitats as natural ecosystems with complex networks of interrelations. most data were col lected on the yamal peninsula. w e attempt to show the practical and theoretical importance of a complex approach to studying tundra ecosystems. the modern state of reindeer pastures in russia from the viewpoint of an ecologist reindeer herding, a traditional activity in russia’s northern regions, is one of the most important factors affecting the state of vegetative cover kryazhimskii & danilov 2000: polar research 19(1), 107-1 10 i07 (andreev 1972; polezhaev 1980; stchelkunova 1992). extensive studies of pastures aimed toward evaluating their foraging possibilities were started in russia in the early 1930s (andreev 1930; sochava 1931; gorodkov 1935; igoshina 1937; avramchik 1939). the research became focused on processes of pasture degradation and their restoration abilities (e.g. andreev 1972: utkin 1977; polezhaev 1980: karpov 1991; dobrinskii 1995). intensive herding of domestic reindeer leads to dramatic changes i n the structure of vegetative cover, lowering its productivity and, consequently, the quality of pastures (stchelkuno va 1992; polezhaev 1993; magomedova 1994). in general, excessive grazing pressure suppresses valuable species of lichens, and results in the replacement of typical tundra plant communities by graminoid-dominated ones. on the other hand, since tundra ecosystems developed under some pressure from reindeer (andreev 1972), complete cessation of grazing also results in changes in the vegetative complex, these changes being negative from the viewpoint of plant productivity and species richness (karpov 1991). apparently, both lack of grazing and overgrazing threaten to degrade the structure of tundra ecosystems as grazing lands for reindeer. therefore, the re sponses of vegetation to grazing pressure are not linear. this non-linearity provides a basis for understanding what conditions are optimal for maintaining the productivity of tundra vegetation for sustainable reindeer grazing. during the 20th century, grazing pressure of domestic reindeer on their pastures in russia has increased significantly. for instance, in the yamalo-nenets autonomous region the numbers of reindeer have doubled since the beginning of the century (fig. 1 ) . recently, rapid industrial devel 500 g 450 w b g 350 8 z g 403 zm 250 ***'****' temporal trend 1 e c o i , , i , i i i , ! i 1900 1910 1920 1930 1940 1950 1960 1970 1980 1 3 9 years fig. 1. numbers of domestic reindeer in the yamalo-nenets autonomous region during the 20th century (dobrinskii 1995). table i . the ratio between fluxes of carbon dioxide from the soil and its intake by vegetation in southern yamal g c02/mz (dobrinskii et al. 1983). intake of c 0 2 flux from release/ the soil intake plant community coz alluvial cereal-sedge 25 15.7 0.63 moss tundra with 6.9 6.4 0.93 meadow rubus chamacmorus and carex spp. dwaft shrubs and cottongrass sphagnum bog with 4.2 4.9 1.17 opment has added to the pressure generated by the increasing herds. in the russian north a unique combination of factors, both natural and artificial, are affecting the natural ecosystems. these ecosystem level changes may have consequences at the global level through their alteration of atmospheric gas fluxes. for example, in situ studies of coz fluxes in different types of plant communities in southern yamal showed that in typical tundra communities the photosynthetic intake of carbon dioxide by vegetation in the peak of the growth season was practically equal to its release by soil respiration, while in meadows the uptake of coz was significantly greater than its release (table 1). these results suggest that if typical tundra communities are replaced by meadow-like ones, dominated by cereals and sedges, as a consequence of heavy grazing pressure, the general balance of carbon in arctic and sub-arctic regions may be altered. the role of small rodents in tundra ecosystems among herbivorous animals, reindeer and small rodents have the most visible influence on the vegetation of tundra ecosystems. the role of small rodents in shaping the appearance of tundra ecosystems in russia was first described by tikhomirov (1959). judging by rough estimations of the mass of dry matter removal by reindeer (polezhaev 1993) and lemmings (danilov 1 9 9 9 , their impact on the vegetation is quantitatively similar. however, the character of this influence is different in reindeer and rodents. in addition to the differences in the diet (small rodents make little use of lichens), the temporal and spatial character 108 reindeer in tundra ecosystems: the challenges of understanding system complexity istics of the impact differ between these two groups of mammals. lemming populations fluctuate, reaching high density at the peak phase (up to 20g300 individualsha), with a biomass of about 5-8 kg/ ha. in years of peak density lemming may reduce above-ground plant biomass by 50-70% (thomp son 1955; pitelka 1964; batzly 1974). during periods of low density, when the impact of rodents on vegetation is practically absent, accumulation of dead parts of plants occurs. (kiryustchenko 1979; danilov 1995). the pressure of rodents on the vegetative cover, therefore, oscillates over time, in contrast to that of reindeer. this cyclic alteration of herbivore pressure was shown to be an important factor in the dynamics of tundra vegetation in the southern yamal (peshkova 1977). rodents also play an important role in the turnover of nutrients in the tundra. it is clear from fig. 2 that significant amounts of potassium, phosphorus and nitrogen that lemmings consume in their food are rapidly released in their urine. 1.10 kg 0.07 kg 0.55 kg 63.1 kg 7 0 60 rp 50 4 0 30 20 10 0 f i g . 2. intake and release of nutrients (n, p and k) and plant biomass by lemmings (lemmus sibiricus and dycrostonix forquafus) during a population cycle in southern yamal (danilov 1995). kg values indicate the absolute value of nutrients involved in turnover, per ha. column segements represent proportion (%) of different components of turnover for each nutrient. this rapid turnover of nutrients can be viewed as natural fertilization, promoting vascular plant growth. the rate of decomposition of faeces of herbivorous mammals is, however, slow usually not exceeding 2% of dry matter per year (malafeev & kryazhimskii 1990; mukhin 1993). thus utilization of faecal nutrients by plants is delayed. this temporal complexity of biotic turnover in tundra is not well known and should be carefully examined. prospects for further studies it follows from the above that there is an urgent need to study tundra reindeer pastures as compo nents of whole ecosystems. there is little hope that sustained production of reindeer pastures can be achieved with the aid of agricultural measures, such as fertilization, seeding etc., since economic justification for such measures is questionable. reindeer herding remains an important use of biological resources in the russian north. the state and dynamics of the natural ecosystems upon which herding is based are dependent on a complex of interactions between a variety of extrinsic and intrinsic factors. however, since tundra ecosystems are relatively simple, it is possible to outline several key biotic components determine the general pattern of its dynamics (schwarz 1971). studying the responses of these components to changes (which are not simple and linear) in both intrinsic and extrinsic factors (including the inevitable continuation of industrial development) should provide information essen tial for the sustainable management of russia’s reindeer grazing systems. w e recommend the following research emphases: 1) comparative studies of productivity, biological diversity, and structure of plant communities under the different pressures exerted by the main groups of herbivorous animals (reindeer and small rodents), as well as under varying levels of industrial development. 2 ) study of the direct and indirect effects of herbivorous mammals (both reindeer and rodents) o n biological turnover and energy flow within the system. 3) study of the role of industrial contamination on the turnover of nutrients in tundra ecosystems. these studies should be based on the modern system approach, taking into account both tem kryazhimskii & d a n i l o v 2000: polar research 19(1), 107-1 10 109 poral and spatial dynamics of the subjects of the studies. acknowledgements. w e are grateful to our colleagues from the institute of plant and animal ecology, ural division of ras: n. v. peshkova, l. n. dobrinskii, yu. m. malafeev, v. a. mukhin and m. a. magomedova for great help with field work or in subsequent discussions. the study was supported by the russian fund for fundamental research (grant no. 99-04-49030) and by the federal programme, “biodiversity.” references avramchik, m. n. 1939: zimnee pitane olenei na yamal’skom severe. (winter feeding of reindeer in northern ydmal.) trudy nii polyarnogo zemledeliya, zhivotnovod.rtvu i pro myslovogo hozvaistvu, ser. olenevodstvo (proc. res. inst. polar agric., ser. reindeer breeding) 4, 7-66. andreev, v. n. 1930: geobotanicheskoe issledovanie tudroyyh olen’ih pastbistch. (geobotanical studies of tundra reindeer pastures.) sovetskiy sever 5 , 101-108. andreev, v. n. 1972: imcheniye antropogennykh vozdeistviy na rastitel’nost’ arktiki i subarktiki. (studies of anthropo genic influence on the vegetation of the arctic and sub arctic.) in: studies of biogeocoenoses of tundru and forest tundra. pp. 4 4 4 9 . leningrad: nauka publ. batzly, g . 0. 1 9 7 4 relationships between lemmings and vegetation in tundra ecosystems. in: proceedings a f t h e first international theriological congress. vol. i . pp. 4 7 4 8 . moscow. bolshakov, v. n., dedkov, v. s., dobrinskii, l. n., korytin, n. s., kryazhimskii, f. v., magomedova, m. a,, nifontova, m. g., semerikov, l. f. & shiyatov, s . g. 1993: dynamics of tundra ecosystems in the west-siberian sectors of arctic: signs of crisis. abstructs of the conference: global change and arctic terrestrial ecosystems. p . 34. oppdal (norway). chernyavskii, f. b. & tkachev, a. v. 1982: populyutsyonnye tsgkly lemmingov v arktike: ekologicheskiye i endokrinolu gicheskiye uspekty. (population cycles of lemmings in the arctic: population and endocrinology aspects.) moscow: nauka publ. danilov, a. n. 1995: the role of lemmings in the biological cycle in southern yamal. russ. j . ecol. 26(3), 203-207. dobrinskii, l. n. (ed.) 1995: priroda yamala. (the nature of yamal.) ekdterinburg: nauka publ. dobrinskii, l. n., davydov, v. a,, kryazhimskii, f. v. & malafeev, yu. m. 1983: funktsional’nye svyazi melkih mlekopitayusrchih s rastitel ‘nost’yu v lugovyh biogeoceno zah. (functional links of small mammals with vegetation in meadow biogeocoenoses.) moscow: nauka publ. gorodkov, v. n. 1935: rastitel’nost’ tundrovoi zony sssr. (vegetation of the tundra zone of the ussr.) moscow: ussr academy of sciences. igoshina, k. n. 1937: pastbistchnye korma i kormovye semny v olenevodstve priural’ ya. (pasture food and feeding seasons in the reindeer herding of pre-urala.) sovetskoye olenevodstvo 10, 125-195. karpov, n. s . 1991: vliyanie vypasa olenei nu rastitel’nost’ subarcticheskoi tundry v yakutii. (the efsect of reindeer grazing on the vegetation of pastures in the sub-arctic tundra of yakuti.ya). yakutsk: ussr academy of sciences. kiryustchenko, s. p. 1979: vozdeistvie lemmingov na rasti tel’nost’ arkticheskoi ekosystemy. (the influence of lem mings on the vegetation of an arctic ecosystem: the example of vrangel island.) in f. b. chernyavskii (ed.): ekologiya polyovok i zemleroyek nu severo-vostoke sibiri. (ecology of voles and shrews in north-west siberia.) pp. 3945. vladivostok: ussr academy of sciences. magomedova, m. a. 1994: lishainiki predtundrovyh lesov zapadnoi sibiri. (lichens of pre-tundra forests of west siberia.) botanicheskii zhurnal 7 9 ( i i ) , 1-1 i . malafeev, yu. m. & kryazhimskii, f. v. 1990: the rate of decomposition of moose excrements in the subarctic. proceedings of the third international symposium on moose. p. 68. syktyvkar: ussr academy of sciences. mukhin, v . a. 1993: biota ksilotrofnyh bazidiomitsetov zapadnoi sibiri. (biota of xylotrophic busidiomycetes of west siberia.) ekaterinburg: nauka publ. peshkova, n. v. 1977: produktivnost’ rastitel’nyh soobstchestv statsionara “khadyta” i vliyaniye gryzunov na travyanistyi pokrov poligonov. (productivity of plant communities of the khadyta station and the effect of rodents on the polygon testing ground.) in n. n . danilov (ed.): biotsenoticheskaya roll zhyvotnykh v lesotundre yamala. (biocenotic role of unimals in yamal forest tundra.) pp. 134-145. sverdlovsk ussr academy of sciences. pitelka, f. a. 1964: the nutrient recovery hypothesis for arctic microtine cycles. in d. j. crisp (ed.): grazing in terrestrial and marine environments. pp. 55-56. oxford: oxford university press. polezhaev, a. n. 1980: izmemeniye rastitel’nosti na pasbistch akh chukotki pod vliyaniyem vypasa. (changes of vegetation at the pastures of chukotka under the influence of grazing.) ekologiya 5, 5-13. polezhaev, a. n. 1993: rastitel’nost’ dal’nego vostoka i eye ispol’zovaniye v olenevodsrve. (vegetation of the far easi and its usage in reindeer herding.) dsc thesis, institute of plant and animal ecology, ural division of russian academy of sciences. schwarz, s. s. 197 i : populyatsionnaya struktura biogeotsenoza. (population structure of a biogeocoenosis.) izvestiya a n sssr, ser. biol., 4 , 458-493. sochava, v. b. 193 i : tundrovedeniye i yageleustroistvo. (tundra science and lichen management.) sovetskii sever i , 78-84. stchelkunova, r. p. 1992: vozdeistviye promyshlennosti i trdnsporta nd olen’i pastbistcha: na primere taimyrd. (effect of industry and transport on reindeer pastures: the example of taymyr.) geografiyu i prirodnye resursy 4,49-55. thompson, d. q. 1955: the role of food and cover in population fluctuation of the brown lemming at point barrow, alaska. trans. north am. wildl. con$ 20, 166-176. rikhomirov, b. v. 1959: vzaimosvyaz’ zhivotnogo mira i rastitel ’nogo pokrova tundry. (interrelation between animals and tundra vegetative cover.) moscow: nauka publ. tishkov, a. a. 1985: rastitel’noyadnye zhivotnye v ekosiste mah tundry. (herbivorous animals in tundra ecosystems.) in v. e. sokolov (ed.): mlekopitayusrchiye v nazemnykh ekosistemakh. (mammals in terrestriul ecosystems.) pp. 38 66. moscow: nauka publ. utkin, v. v. 1977: ob izmenenii rastitel’nosti na lesotundrovyh pastbistchah r. pechory vsledstviye mnogoletnego vypasa olenei. (on the change of vegetation in forest-tundra pastures of the pecbora river as a consequence of long-term grazing of reindeer.) in: meloratsiya zemel’ krainego severa (meliora tion o j territories of the f a r north.) pp. 243-250. moscow: agropromizdat. 110 r e i n d e e r i n tundra e c o s y s t e m s : t h e c h a l l e n g e s of u n d e r s t a n d i n g s y s t e m complexity bookreviews03.indd 211book reviews 2004: polar research 23(2), 209–213 one sighting card were provided. voluntary census takers also want to know where the data they have collected end up. a free-text search for “marine mammals” or “svalbard” on the norwegian polar institute website gives no hits. this doesn’t detract from the book in any way, but people would be more eager to send in observations if they could trace their contributions in the ongoing data compilation. the book is good and makes you hungry for more. it is also refreshing that the book keeps to the point, but what is the purpose of the map on page 1? why not a map showing the ranges of the animals the book is about? moreover, hunting of marine mammals has dominated svalbard’s history from the early whaling days to the polar bear hunting of modern times. hunting in svalbard and its devastating effect on these mammals would have been a more interesting topic than general comments about bowhead whales, steller’s sea cow and sea otters. the sections on seals and whales should both begin with a few general words concerning the relationships between the species and their evolution. the text is packed with interesting information, but a discussion of the future is called for: not just the future of the whales but of all svalbard’s marine mammals. if the ice at the north pole melts away, will there still be polar bears in svalbard? how many polar bears have been killed since they became protected? tourists ask a lot of questions; the authors would surely be able to provide answers. hopefully the next edition can provide indications of size for the whales on the identifi cation sheet. are they all rendered at the same scale? greater consistency in presenting the whales’ weight and size in text would make reading easier. for instance, it would be interesting to know where the fi gure 200 tonnes for the blue whale comes from, and what the average weight is. could the authors provide a few more references? as the number of tourists grows, it would be worthwhile listing the names of the whales in even more languages. the book is so good no nature-loving tourist going to svalbard should be without it. for people like myself, who guide tourists in experiencing svalbard’s fauna, the book is a gold mine, with its logical structure and clear text. it is affordable, easy to take along, and answers the questions. and when the sighting reports start coming in, it will hopefully lead to better knowledge about the marine mammals of svalbard. review of negotiating the arctic: the construction of an international region, by e. c. h. keskitalo (2004). new york and london: routledge. 282 pp. isbn 0-415-94712-x. oran r. young bren school of environmental science and management. university of california (santa barbara), 4518 bren hall, ucsb, santa barbara, ca 93106-5131, usa. since the waning of the cold war during the late 1980s, the arctic has emerged as a lively arena for initiatives designed to promote international cooperation. these initiatives take a variety of forms. some, like the arctic environmental protection strategy (aeps) and its successor the arctic council (ac), involve intergovernmental agreements. others, such as the northern forum (nf), are collaborative efforts on the part of subnational units of government (e.g. counties, provinces, states). still others, like the international arctic science committee (iasc), the university of the arctic (uarctic), and the inuit circumpolar conference (icc), feature efforts on the part of nongovernmental bodies to infl uence the course of transnational relations. how can we explain this development? and what are the prospects for a broadening and deepening of arctic cooperation during the foreseeable future? this intriguing, albeit sometimes diffi cult and frustrating, book seeks to answer these questions by focusing on the idea of region-building, deploying the methods of social constructivism, and making liberal use of discourse analysis. the result is an analysis that has the salutary effect of making us stop to think about the underpinnings of cooperation in the arctic, even though it may have little impact on the actual course of events in this dynamic region. is there an arctic discourse? what methods are appropriate for answering this question? keskitalo’s central argument is that such a discourse has emerged during the last 20-30 years and that it refl ects in large measure the views and perspectives of canada and, to a lesser degree, those of the icc (treated as a partner of canada with regard to circumpolar issues). the evidence underlying this 212 book reviews proposition deals, for the most part, with the determination of appropriate boundaries for the arctic as a region and the framing of the arctic policy agenda in terms of issues involving environmental protection, indigenous claims, and frontier development. although the story keskitalo unfolds regarding the emergence of an arctic discourse is intriguing, i am not convinced that the evidence supporting this line of analysis is compelling. it is true that there is a kind of disconnect between north american and russian perspectives on the arctic on the one hand and european perspectives on the other. but the boundaries of this emerging region owe as much to the effects of political manoeuvering and the preferences of those working on issues of pollution and the conservation of fl ora and fauna as they do to the success of canada in dictating the boundaries of the region. far from achieving consensus regarding the framing of issues on the arctic agenda, those active in arenas like the ac and the nf still tend to talk past each other in extolling the relative merits of environmental protection and sustainable development as conceptual lenses for the analysis of arctic issues. what is more, participants in these processes are often struck by the diffi culty canada has in arriving at a national consensus regarding arctic issues, much less inducing others to buy into canadian ways of thinking in this realm. above all, keskitalo’s account of the emerging arctic discourse offers no mechanism for structuring or disciplining thought regarding appropriate ways to resolve issues of environmental protection and sustainable development under conditions prevailing in the arctic. as those of us who are active in ac and nf meetings know all too well, efforts to promote transboundary cooperation in the arctic often refl ect a cacophony of voices rather than the application of a coherent discourse to a more or less well-defi ned collection of issues. how can we explain the emergence of the arctic as a distinct region in international society over the last two or three decades? to answer this question keskitalo develops the argument that canada (along with the icc) has acted as the pivotal player in this drama, with the result that the arctic agenda is really a canadian agenda for what canadians (as well as some europeans) call the “northern dimension”. without doubt canada has played a prominent role in the evolution of transbounday cooperation in the arctic. with russia preoccupied with internal issues, the united states dragging its feet, and the nordics possessing limited capacity to call the shots, canada has taken the lead at a number of key points in the development of international cooperation in the arctic. as keskitalo correctly observes, canadian leadership was particularly important during the mid 1990s in the run-up to and immediate aftermath of the creation of the ac. even so, i fi nd the case for canadian dominance in this process somewhat unconvincing. it is easy to fi nd examples of proactive leadership on the part of other players, as in the role finland played in the process leading to the establishment of the aeps in 1991. whenever the united states (and to a lesser degree russia) becomes annoyed and resists the placement of important issues (e.g. issues relating to the harvesting of marine mammals) on the arctic agenda, canada has little choice but to back down. canada itself is a multi-cultural society most of whose citizens have little knowledge of or interest in the arctic, even as they ritually repeat the dogma of “the true north strong and free” enshrined in their national anthem. in short, canada lacks the power and (often) the will that constitute critical ingredients in successful efforts to impose a discourse on others. canada has played an active role in settings like the ac. but as soon as its initiatives run into opposition, the limits of canada’s ability to infl uence the course of arctic affairs become apparent. what are the consequences of region-building in the arctic and the spread of the ideas that go with it? a persistent subtext of keskitalo’s analysis of canadian infl uence is the proposition that the emerging arctic discourse overlooks or even clashes with the geographical, social, and political realities of fennoscandia and the nordic world more generally. if i understand her correctly, she regards this as a signifi cant fl aw in arctic region-building. but is this a fair assessment? finland has played a key role in framing numerous issues of environmental protection in the arctic. finland and norway have emerged as the mainstays of support for the university of the arctic. denmark has taken the lead in nurturing and supporting the indigenous peoples secretariat, which now plays a critical role in facilitating the participation of indigenous peoples in the ac. iceland has assumed a highly proactive role as the current chair of the ac. what is more, there are undeniable similarities between the nordics and the other arctic states when it comes to the problems of maintaining vital human settlements in their northern peripheries. 213book reviews 2004: polar research 23(2), 209–213 even relatively centralized countries like norway and sweden have struggled with this well-known feature of core–periphery relations. i do not mean to suggest that keskitalo is wrong to emphasize the differences between the european arctic and the northern american arctic and the russian arctic. but i believe it would be incorrect to infer from an account of these differences that nordic policymaking regarding arctic issues has been highjacked by the canadians. there are perfectly good interest-based explanations for the active participation of countries like finland and norway in arctic region-building. there is also considerable variation among the nordic countries in this realm. for instance, sweden, which has a particularly strong interest in baltic cooperation, has played a more subdued role in the ac than finland and norway. in my experience, scandinavians active in bodies like the ac show no signs of suffering from false consciousness regarding the virtues of region-building in the arctic. what can we say about the future of arctic region-building? although she does not address the issue directly, keskitalo’s analysis is suggestive with regard to this question. converging or congruent interests can suffi ce to trigger specifi c developments like the creation of the ac and the nf. but regions tend to gel and become lasting political arenas when they give rise to social practices and take on a life of their own that transcends the interplay of well-defi ned interests among individual members. whatever its provenance, the growth of an effective arctic discourse could play a crucial role in these terms. from this vantage point, the future of regionbuilding in the arctic is hard to forecast at this stage. interest-based initiatives have produced a level of international cooperation in the arctic that goes well beyond what most of us could have anticipated twenty years ago. yet i would argue that arctic cooperation remains relatively fragile, precisely because it is based largely on convergent but transient interests in contrast to shared experiences in the past and a shared vision of the future. would the continuation of region-building in the arctic be a good thing? where you stand concerning this question undoubtedly depends on where you sit. the development of social practices never yields perfectly symmetrical results. even in cases that produce gains for all parties concerned, some participants are apt to be bigger winners than others. if i read her correctly, keskitalo is troubled by the thought that canadian dominance might marginalize the nordic countries in arctic regionbuilding and, in the process, box them into a social practice that fails to serve them well over the long run. keskitalo is undoubtedly right to draw our attention to the impacts of ideas on interests in evaluating the consequences of arctic region-building. but here, too, i am skeptical about the argument as presented. my perception is that most nordic policymakers are generally positively disposed toward arctic region-building and that they know exactly what they are doing in this regard. of course, it is possible that they will experience a rude awakening regarding this issue somewhere down the line. but i doubt it. for the most part, keskitalo’s scholarship is excellent. she has done a commendable job of tracking down primary sources, and she uses them to good advantage. nonetheless, minor inaccuracies creep into her text from time to time. the u.s. arctic research and policy act of 1984 did not mandate the work of the committee on arctic social sciences, which i co-chaired (p. 41). the 1973 calder case involving the land claims of aboriginal peoples in canada did not deal with the controversy over a proposed pipeline in the mackenzie valley corridor (p. 133). canada did not take the lead in the creation of the nf (p. 160); the governor of alaska organized a conference held in anchorage during 1990 that provided the impetus for the establishment of the nf. in addition, the text of this book is often rather opaque, making the thread of the argument diffi cult to follow in some places. this book would have benefi ted greatly from attention on the part of an english-speaking copyeditor. still, it would be wrong to make too much of these shortcomings. although it is apparent from what i have said that i am not persuaded by some of the principal arguments of this book, i am convinced that it is a useful addition to the literature on international cooperation in the arctic. most of the existing literature in this realm refl ects a somewhat naive enthusiasm for region-building in the far north. keskitalo has brought fresh eyes to this topic and developed an argument that requires us to stop and think about the origins and consequences of international cooperation in the arctic. while others may join me in responding skeptically to specifi c arguments presented, their understanding of what is at stake in the arctic will be sharpened substantially as they work their way through the analysis set forth in negotiating the arctic. interrelationships between egg dimensions, pore numbers, incubation time, and adult body mass in procellariiformes with special reference to the antarctic petrel thalassoica antarctica * f. mehlum, h. rahn, c. bech a n d s. haftorn mehlum, f., rahn, h., bech, c. & haftom, s. 1986: interrelationships between egg dimensions, pore numbers, incubation time, and adult body mass in procellariiformes with special reference to the antarctic petrel tbalassoica antarctica. polar research 511,s.. 53-58. dimensions of eggs and eggshells and pore density are reported for eggs of the antarctic petrel thalassoica antarctica(as well as eggs of the snow petrel pagodroma nivea). allometric relationships are used to estimate the initial egg mass, total number of pores and incubation time. the initial egg mass for antarctic petrel was estimated to 83 g. and the incubation time to 55 days. the total pore number in antarctic petrel was estimated to 4212 and in snow petrel 2654 pores per egg. using data from 8 species of procellariiformes, the relationship between total pore counts, initial egg mass and incubation time is described. fridrjof mehlum. norsk palarinstitutt. p.o. bor 158, n-1330 oslo licfrhavn. n o w a y ; hermann rahn. department of phwio1og.v. state university ($ new york. bujjalo. n . y . 14214. u s a ; claus bech. department of zoology. university of trondheim. n7055 dragvoll. n o w a y ; svein haftom, the museum. university of trondheim. erling skakkesgate 47a. n-7000 trondheim. norway: october 1986 (revised february 1987). the initial egg mass at the time of laying is a n important reference point because of its correla tion with various egg parameters, e.g. eggshell dimensions, number of pores in the eggshell, incubation time, and adult body mass. allo metric relationships that have been established allow one to predict many of these, and other functions, once the initial egg mass is established. initial egg mass and various egg dimensions of the antarctic petrel have only scarcely been reported. schonwetter (1 960) presents data based on a single egg only, and orton (1968) gives values of mass, length and width, but d o not list the nuinber of specimens nor provide data for egg shell dimensions. the data presented here were collected at the end of the incubation period and d o not represent initial egg mass. eggs o f the order procellariiformes lose water during their incubation period (grant et al. 1982a), which is similar in amount to that of other birds (n = 8 i ) , and average 15% of the initial egg mass (ar & rahn 1980). in this study we report dimensions for 2 1 eggs and eggshells and pore density for 9 eggs of the antarctic petrel (as well as 16 and 3 eggs for dimensions of eggs and eggshells, respectively, of the snow petrel pagodroma nivea), which allow one to estimate the initial egg mass based on allometric relationships of egg dimensions versus egg mass established for 69 species of procellarii formes. once the initial egg mass is known, one can calculate the total number of pores per egg and, furthermore, predict from other allometric relationships the incubation time and adult body mass for this species. the eggs were collected during the norwegian antarctic research ex pedition 1984185 at the breeding colony svart hamaren (71"53's, 5" io'e) located in dronning maud land (mehlum et al. 1985). methods length and width dimensions were obtained with calipers and read to the nearest 0.1 mm. * publication no. 87of the norwegian antarctic research expediiions ( i 9841851. 54 shell thickness was measured in each egg at twenty different points, using a ball-point caliper which could be read to 0.01 mm. the shell thick ness measurement included the dried membranes adhering to the shell. pore density was etablished as follows: pieces of eggshell from various regions were boiled in 5% (g/l) koh solutions for several minutes to remove all proteinaceous material. they were then etched by being dipped briefly in concentra ted nitrid acid for a predetermined period of about 15 seconds, which enlarges the pores. after drying, the inside of the shell was painted with a concentrated water solution of evans blue dye. by capillary action this solution fills the pores which now become visible at the outer shell sur face as blue spots against a white background and can now be counted with a dissecting scope. the counting iield was 0.25 cmz, and twenty fields representing various regions of each egg were counted (see fig. i ) . these averaged values where multiplied by 4, expressing the pore density per cm?. the latter value is factored by the total surface area of the egg derived from the relation ship a (cm2) = 4.835 w’.“’ (paganelli et al. 1984) where w = initial egg mass (g). fig. i . photograph of a 0.25 cm’ shell area showing tjpical distribution of dye-stained pores which had results and discussion prediction of initial egg mass table i shows egg mass, egg and shell dimensi ons previously reported, and those obtained in this study. we have estimated the initial egg mass from the regression of length and width dimensi ons as a function of egg mass based on 88 corre lates (69 species) listed by schonwetter (1960) for the order procellariiformes shown in fig. 2. the xsee is 1.03 and 1.02 for the length and width correlates, respectively, where xsee is the anti log of see (standard error of estimate) = value by which y is multiplied or divided. the projection of 70 mm length and 48 mm width (from table 1 ) on fig. 2 predicts a n initial egg mass of 80 and 86 g, respectively. thus, a n average value of 83 g is a reasonable prediction for the initial egg mass from this particular nest site. the pore density and number ofpores the average pore density for nine eggs was 11.7/0.25 cm’, or 46.8 cm-’ (table 2). the total egg surface calculated (see methods) on the basis of an egg mass of 83 g = 90 cm2. thus, the total number of pores = (46.8 x 90) or 42 12 pores per egg. table 3 gives egg and eggshell dimensions for the snow petrel and a pore density of (10.7/0.25 cm2) or 42.8 c m 2 for three eggs. the surface area for the 47 g egg is 62 cm2 and the total pore number = (42.8 x 62) or 2654 pores per egg. i n table 4 are listed the egg mass, incubation time, and pore number of nine species of the order procellariiformes, including the two reported from this study. they have been ranked accor ding t o egg mass. the number of pores is only 50-60% of that predicted from the regression established for 161 species (ar & rahn 1985). thus, for a given egg mass the pores of the order procellariiformes are significantly fewer, which appears to be related to their prolonged incubati on time (see below). when pore numbers in table 4 are regressed against the relative growth rate of embryos, expressed as egg mass divided by incubation time (g.day-’), the slope is essenti ally 1.0, a relationship that describes the pore prevrouslv been enlarged by acid etching. number for birds in general (ar & rahn 1985). 5 5 table i . egg mass, egg and shell dimensions of the antarctic petrel thalassoica antarctica. egg shell reference mass length width n mass thickn. n mm mm g mm area g ~ antarctic continent 95 71.4 50.0 1 7.14 0.35 1 schonwetter 1960 70.0 48.0 orton 1968 wilkes station 90 dronning maud land 70. i 48.6 21 1.29 0.406 9 thisstudy s.d (3.1) (1.5) (1.01) (0.032) 100 e e 0.361 length 14.08 w n = 88 r = .998 10 10 5 50 r = ,998 see = x 1.02 i) 5 10 fig. 2 . regression of egg length and egg width upon egg mass f o r 69 species and 19 subspecies oj’the order procellari$onnes takenfrom the tables of schonwetter ( 1 960). setting aside the unusally high pore count of pterodroma hypoleuca in table 4, the pore count of procellariiformes is best described by the relationship, the number of pores, n = 3100 (w/i), s.d. 440, where w = initial egg mass, g, a n d i = incubation time, days. incubation rime in fig. 3 are plotted the incubation times against egg mass for 475 species excluding the order procellaniformes (grant et al. 1982a). the dotted lines mark the limits for k see. the shaded 56 table 2 . pore density (number of pores per field of 0.25 cm') for nine eggs o f the antarctic petrel thalassoica anrarcrica. for each egg 20 fields were counted and averaged. egg no. 2 3 4 5 7 8 9 10 ii grand mean pore density 10.1 12.0 13.3 15.3 9.8 10.4 11.7 13.5 8.8 11.7 s.d. 2.0 2.2 3.8 2.8 2.1 2.6 2.7 3.4 2.2 2. i table 3 egg mass. egg and shell dimensions, and pore density o f t h e snow petrel pugodroma nivea area m a s s length width n mass thickn. n reference g mrn mrn g mm s. georgia. s. orkney 47.0 56.5 40.2 15 3.40 0.27 i5 schonwetter 1960 davis station 47.4 55.5 39.4 21 dronning maud land 56.7 39.2 16 3.42 0.28 3 thisstudy brown 1966 s.d ( 2 . 1 ) (1.0) pore density (number of pores per 0.25 cm') egg no. i 4 7 g r a n d m e a n pore density 11.3 11.7 9.2 10.7 s.d. 2.8 2.8 2.2 1.3 table 4. egg mass, incubation time. and number of pores per egg in 9 species of the order procellarii formes. species egg incun o . refe mass bation pores rence g days diomedea exu1an.r )) nigripec u rrnmurabilrs fulniarus glaciali.~ i7iala w ) i c a anrarcrica frerodroma phaeopygia fullinus pac$nrs pagodroma nivea pterodroma hypoleuca 500 78 30.5 66 2 8 5 65 i 0 1 49 x 3 ( 5 5 ) 77 5 5 57 52 47 45 39 49 19.698 16.700 15.753 5.210 4.2 i 2 4.544 3.747 2.654 4.159 i 1 1 & 3 4 5 6 4 7 ~ re/erence.t : ( 1 ) tullett & board 1977; ( 2 ) grant et al. i982a; ( 3 ) rahn et al. 1984a: (4) this study; ( 5 ) whittow et al. 1983:(6)whittow 1 9 8 4 ; ( 7 ) g r a n t e t a l . 1982b. region above shows the regression .+ see for 38 species of the procellariiformes where the incu bation times were taken from watson ( 1 975) and other sources, and the corresponding egg weight from schonwetter (1960). for the procellariifor rnes the regression is-incubation time, i = 31 w0.l3'', + = 0.82 and x s e e = 1.1 1. for an 83 g egg of the antarctic petrel one would predict an incubation time of 55 days (range 50-61 days for f 1 see). this predicted value is larger than the reported incubation period of 40 -45 days (orton 1968; j.a. van franeker pers.comm.). the shortening of the incubation period compared to other procellariiformes may be an adaptation for breeding in the hostile climate on the antarctic continent. adult body weight and egg mass from the egg weight (schonwetter 1960) and adult body weight (warham 1977; lack 1968) the regression in fig. 4 is plotted for 67 correlates representing 50 species of the order procellarii formes. the regression for egg mass, w = 0.7 13 fjw0.-3s , f = 0.98, x s e e = 1.17. for non passerine birds (n = 557) a similar regression was reported (rahn et al. 1985) where w = 0.399 bw'.''', f = 0.89, and xsee = 1.48. 57 80 70 to 50 lo . -. .. . 30 m.. 20 . . ,, . , -. . ~ 15 i 1 1 i i l l i i i i i l l l i 1 1 1 i 1 i1,x) . ' to too rn egg weight ( g ) '9 fig. 3. regression of incubation time upon egg mass. upper shaded region for 38 species of the order procellarii formes. lower regression for 475 non-passerine birds. for details see text. (from grant et al. 1982a). frocellariforrnes 'ooo 7 100 1 2. / t . , &y ,," yo' ' 0 735 w 10713 bw n 67 (50 species) r = ,992 see= ,067.x i 17 1 'i'o too 1000 10, body weight, g 30 fig. 4. regression ofegg mass upon adult body mass for 50 species (n = 67) of the order procellariiformes. 58 while t h e e x p o n e n t s of t h e s e t w o regressions are n o t significantly different, t h e intercept f o r t h e procellariiformes is (0.7 13/0.399), or i .8 times larger t h a n i n n o n p a s s e r i n e birds. the relatively larger eggs o f this order h a v e b e e n described previously ( r a h n e t al. 1975; rahn e t al. 1984b). we h a v e a l s o regressed a d u l t body mass against egg mass for t h e procellariiformes using the same correlates as a b o v e . this regression is a d u l t body mass, bw = 1.73 w1.’4, 9 = 0.98, and xsee = 1.23. solving this e q u a t i o n for a n 83 g egg mass o f t h e antarctic petrel predicts an a d u l t body weight of 645 g, w h i c h can be compa red with 641 g ( n = 34) given by bierman & voous (l950), cited by w a r h a r n ( l 9 7 7 ) , and 609 g ( n = 20) obtained in t h i s s t u d y . references ar, a. & rahn, h . 1980: water in the avian egg: overall budget of incubation. amer. zool. 20,373 -384. ar, a. & rahn, h . 1985: pores in avian eggshells: gas conductance, gas exchange and embryonic growth rate. respir. physiol. 61, i 20. bierman. w . h . & voous, k . h . 1950: birds observed and collected during the whaling expeditions of the willem barends in the antarctic. 196-1947 and i947 1948. ardea 37.1 123. brown, d.a. 1966: breeding biology of the snow petrel pagodroma nivea (forster). anare scient$c re ports ser. b ( 1 ) 89. grant, g.s., pettit, t.n., rahn, h., wittow, g.c. & paganelli. c.v. i982a: water loss from laysan and black-footed albatross eggs. physiol. zool. -55, 405 4 i 4. grant. g.s.. pettit, t.n., rahn, h., whittow, g.c. & paganelli. c.v. 1982b: regulation of water loss from bonin petrel plerodroma hypoleuca) eggs. auk 99, 236-242 lack, d. 1968: ecological adaptations .for breeding in birds. methuen, london. mehlum, f., bech, c. & haftorn, s. 1985: omithologi cal investigations in miihlighofmannfjella, dron ning maud land. pp. 27-34 in orheim, 0. (ed.): report of the norwegian antarctic research ex pedition ( n a r e 1984185). nor. polarinst. rapport. 22. i38 pp. orton, m.n. 1968: notes on antarctic petrels 7halas mica antarctica. emu 67.225-229. paganelli, v.c., olszowka, a. & ar, a. 1974: ‘ h e avian egg: surface area, volume, and density. condor 76, 3 19-325. rahn, h., paganelli, c.v. & ar, a. 1975: relation of avian egg weight to body weight. auk 92.750-765. rahn, h., greene, d.g.,taien, o., b o g , j . & mehlum, f. 1984a: estimated laying dates and eggshells con ductance of the fulmar and brunnich’s murre in spitsbergen. ornisscand. 15.110114. rahn, h., ackerman, r.a. & paganelli, c.v. 1984b: eggs, yolk and embryonic growth rates. pp. 89112 in whittow, g.c. & rahn, h. (eds.): seabird energe rics. plenum press, new york. rahn, h., sotherland, p.r. & paganelli, c.v. 1985: interrelationships between egg mass and adult body mass and metabolism among passerine birds. j . om. 126.263271. schonwetter, m. 1960: handbuch der oologie. meise, w. (ed.). akademie verlag, berlin. tullett, s.g. & board, r.g. 1977: determinants of avi an eggshell porosity. j . zool. london 183.203-21 1. warham, j . 1977: wing loadings, wing shapes and flight capabilities of procellariiformes. new zealund j . zool. 4.73-83. watson, g.e. 1975: birds of the antarctic and sub anrarcric. amer. geophysic. union, washington, d.c. whittow, g.c. 1984: physiological ecology of incubati on in tropical seabirds. pp. 47-72 i n schreiber, r. (ed.): tropical seabird biology. studies in avian bio log^^. no. 8. cooper ornith. soc. whittow,g.c.,simons,t.r. & pettit,t.n. 1984: water loss from the eggs of a tropical seabird (plerodroma phaeopygialat high altitude. comp. biochem. physiol. 78a.537-540. proceedings of the international symposium on polar aspects of global change tromsq, norway, 24-28 august 1998 preface the first ideas for this symposium were presented several years ago at scar and iasc meetings. they were based on the realization that there had apparently never been such an interdisciplinary bipolar meeting. the intent of the symposium was to provide a current assessment of the role of the polar regions in global change. contributions were requested primarily on subjects that were not narrowly of interest to researchers working only in one hemisphere. this aim was achieved for almost every session. dealing with social issues, the ninth session was the exception. here nearly all papers concerned the arctic. keynote addresses by gunter weller. chris rapley and hartmut grass1 began the symposium, highlighting the reasons why i t was timely and important. together with the over 120 presentations, these addresses also identified both what is known and gaps in our knowledge. attended by 240 participants from 21 nations, the symposium was the first major scientific meeting organized by the norwegian polar institute (norsk polarinstitutt) after its move north of the arctic circle, to tromso. although the main office building at the new polar environmental centre would not be completed for another six weeks, we were proud to give symposium participants a preview of the centre's facilities and a visit to the exhibition centre polaria, which had opened to the public earlier i n 1998. the symposium achieved its major aim of bringing together scientists from different disciplines and different regions. numerous fringe meetings were conducted at the margins of the conference. vigorous interactions were observed both in the meeting rooms and at the social events, and not least during the sold-out post-symposium excursion to svalbard. the symposium was jointly sponsored by the international arctic science committee (iasc) and the scientific committee on antarctic research (scar). co-sponsors were the european polar board, the nordic council for polar research, the university of tromsg, the commission for scientific research in greenland, the international glaciological society, the arctic monitoring and assessment programme (amap), the world climate research programme (wcrp)/the arctic climate system study (acsys). and the international arctic research center (iarc). the general scientific planning committee initially comprised charles bentley, gunter weller and olav orheim. the scientific steering committee was later established with weller and bentley as chair and co-chair, and augmented by the session chairmen. the latter took on the task of planning and organizing their sessions, including selecting oral presentations. a local organizing committee was led by orheim and had members from the university of tromso, the norwegian polar institute and the polar environmental centre. the event lasted four days and consisted of the following nine sessions (chairmen in parentheses): 1999: polar research 18(2), 113-1 14 1 1 3 1) climatic trends in the arctic and antarctic (gunter e. weller) 2) teleconnections linking the polar regions to low and mid-latitudes ( h u t aagaard) 3 ) terrestrial systems and feedbacks on climate change (torben r. christensen) 4) variabiliry of polar snow, ice and permafrost features (jon ove hagen) 5 ) ice sheets and glacier mass balance and sea level (philippe huybrechts and vladimir 6) biogeochemical cycles in the arctic and antarctic (paul treguer) 7 ) the circumpolar arctic/antarctic palaeoenvironmental record (olafur ing6lfsson and jorn 8) atmospheric chemist?, ozone and uv-b effects (edward c. de fabo) 9) regional and socio-economic impacts of global change (louwrens hacquebord) some 50 oral presentations were made and about 70 posters set up. about half of these presentations were eventually submitted to polar research for inclusion in the published proceedings. with the assistance of the session chairmen who subsequently served as special editorial advisors for the proceedings issue, papers underwent the rigours of the peer review process. it posed a stiff challenge for authors to address the critiques of two or three referees as well as those of the editor and the advisors while keeping the paper within the strict page limit set in 1998. the authors of the 36 articles printed in the following pages are those who met this challenge. some submissions which could not be pared down will be published in subsequent issues of the journal. the editor is grateful to the contributors and referees for their hard work. to show the journal’s appreciation, we have printed a list of referees at the back of this issue. the editor would also like to thank the editorial advisors, who were vital to the success of this collaborative effort. kotl y akov) thiede) olav orheim, director, norwegian polar institute helle valborg goldman, editor-in-chief, polar research 114 preface: proceedings of the international symposium on polar aspects of global change patterns of production and sedimentation in the boreal and polar northeast atlantic paul wassmann. rolf peinert and victor smetacek wassmann, p., peinert, r. & smetacek, v. 1991. patterns of production and sedimentation in the boreal and polar northeast atlantic. pp. 209-228 in sakshaug. e., hopkins, c. c. e. & 0ritsland. n . a. (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, 12-16 may 1990. polar research 10(1). pelagic systems are potentially capable of retaining and recycling all autochthonous organic material. although some losses due to sinking particles inevitably occur. relating processes in the surface layers quantitatively to vertical particle flux is difficult because only a small percentage of the total production is lost annually via sinking in the open ocean. further. only a few types of particles contribute to this flux and only a small proportion of these may actually reach greater depths. measurements of vertical flux with sediment traps revealed seasonal and regional patterns also within the northwestern atlantic and indicate imbalances betwccn particle formation and dcgradation. the classical pattern of spring bloom sedimentation followed by reduced loss ratcs has bccn found in \hclf and shallow water regions such as the norwegian coastal current and fjords and is also cncountcrcd in the barcnts sea. i n the norwegian sea. however. the seasonal pattern appears different as thc seasonal maximum has been observed during late summcr/autumn. the physical environment determines nutrient avdihbility and hence the particles potentially available for sedimentation. the relationship betwccn phytoand zooplankton govcrns vertical flux seasonality. and zooplankters with different life cycles and feeding strategies further modify the principle patterns. her bivores with life-cycle strategies involving overwintering of large biomass and predictable seasonal appear ance (copepods. cuphausiids) will have a different impact than opportunistic organisms with vcry ion overwintering biomass, for example salps and ptcropods. the latter exhibit much greater interannual biomass variation and may thus contribute to interannual variability of the vertical flux. shelf systems of similar latitude arc generally comparable w i t h rcspcct to their flux patterns and also share timilarities w i t h marginal ice zoncs. open ocean systems as the norwegian sea. however, cxhibit different patterns which are similar to the subarctic pacific. puul wassmann. n o r w g i a n college of fishery science. uniiier.~itv of trurnsc. p . 0. box 3083 g u l e q , n-9001 trornsg. n o r w a y ; rolf peitiert. instirut f u r meereskiiiide. dusternbrookerweg 20. 0-2300 k i d i . federal republic of germany; victor smetacek. alfredwegener-lnstitut f u r polarund meere.\ forschung. a m handelshafen 12, d-2850 bremerhaoen. germany. introduction sediment trap deployments conducted in the seventies in localities as disparate as the deep sargasso sea (deuser & ross 1980), the baltic sea (smetacek e t al. 1978) and the shallow waters of kiel bight (smetacek 1980a) revealed a strik ingly common feature. t h e annual sedimentation pattern was dominated by a strong pulse following the spring bloom with lower rates during the rest of the year. a n additional autumn maximum in kiel bight could be related t o the autumn blooms which occur there regularly but not in the other areas. this spring pulse was accepted as the para digm case for waters experiencing a spring bloom. t h e combination of insolation, shallowing of the mixed layer d u e t o fresh-water run-off, melt ing ice and/or solar warming and high con centrations of winter-accumulated nutrients in the euphotic zone provide the basis for the spring phytoplankton bloom (fig. 1). it starts normally in march in the boreal zone and a second bloom might take place in august/september when nutrients are mixed upwards from deeper layers. the spring phytoplankton bloom starts in april or later in the arctic and since light reaches limiting values by september, only o n e bloom occurs. the low herbivore biomass at the end of the winter period and the resulting low grazing pressure results in a slow response of zooplankton to increasing food supply, particularly in the arc tic (heinrich 1962; smetacek et al. 1984; peinert et al. 1989; tande 1991 this volume). a s a result, extensive sedimentation of ungrazed phytoplank ton and phytodetritus takes place during the sen escent stage of the spring bloom. despite the pulsed nature of vertical flux, 210 p . wassmann, r . peinert & v . smetacek i . -_-_-i .______ a boreal ltght 1 -\\\ -____-_-’ .______ a slrathcat8on ii and numen1 concentral8on 8n the eupholc zone (i _ _ _ _ _ _ _ regeneraled pinduction regenefaled production ~ _ _ _ . new prodvclbon new production phytoplank ton zooplankton annual integrations of sedimentation acquired from early t r a p deployments yielded a linear-log relationship with annual primary production in the overlying water column (suess 1980). recently, wassmann (1990) has shown that such a simple model can be applied t o boreal coastal waters of the north atlantic. in the early eighties, it was widely accepted that the sedimentation rate in a given region could be ascertained from knowledge of primary pro duction: the higher the production, the greater the proportion settling o u t (berger et al. 1989). the concept of primary production, however, underwent a differentiation since we now dis tinguish “new” from “regenerated” production (eppley & peterson 1979) and the “new” pro duction sets the upper limit t o particle flux out of agiven water column (platt et al. 1988). it seemed reasonable t o assume that major flux pulses would , follow periods dominated by new production, i.e. the spring bloom (fig. 1). attention next focused on the processes that control the vertical flux of particles from the mixed layer (cadee 1985; alldredge & silver 1988; lampitt et al. 1990). during the eighties, sediment traps were deployed in a variety of localities. results from these studies indicate that annual patterns in dif ferent regions can deviate substantially from the fig. 1 . conceptual diagram of seasonal changes in physical factors, phytoplankton stocks, new and regenerated production and sedimentation for boreal and arctic areas. they merely demonstrate its restricted appli cability. indeed, implications arising from an assessment of the recent data o n vertical flux are already overturning another, older paradigm: the implicitly accepted patterns of the annual cycles of phytoplankton and zooplankton as exemplified by the curves of heinrich (1962) which represent different regions of the world ocean. w e now know that these might well be basic types dic tated by the physical environment, but in fact the variability is much greater than previously envisioned. sediment traps a r e powerful tools in furthering o u r understanding of the dynamics of pelagic systems (gofs 1989). they not only collect the material settling o u t of the upper layer but also demonstrate which types of suspended particles d o not sink o u t , or d o so only rarely. inter regional and inter-seasonal comparisons ( h o n j o 1990) provide a very useful framework to inter pret, in ecologically meaningful terms, the per plexing data now being derived from sediment trap deployments. complications of primary production rates in the world ocean (e.g. koblentz-mishke e t al. 1970) as well as satellite-derived phytoplankton pigment distribution in the north atlantic (brewer et al. 1986) indicate that the northeast spring maximum paradigm that emerged during 1 atlantic is highly productive. this area is charac the seventies. considerable interannual variation terised by vast shelf areas including t h e north sea in rates and even patterns recorded from the same and the barents sea that a r e open t o exchange region have also come to light (deuser 1988). t h e with ocean basins (figs. 2 and 3). in contrast to new data d o not disprove the earlier paradigm. the circular flow of the north pacific gyre, warm production and sedimentation in the northeast atlantic 21 1 r o o fig. 2. topography of the boreal and polar northeast atlantic (200 and 1mx) m contours) and sediment trap mooring sites referred to in the text. li = lindlspollene; f a = fanafjorden; v p = vdring plateau; ncc = norwegian coastal current; na-i = aegir ridge-1; nb-1 = jan mayen; lb 1 lofoten basin; b a = balsfjorden; bi-1 = bjdrneya; bs = barents sea sampling area (thin broken line); fs-i = fram strait; gb-2 = greenland basin. also shown is the sea ice cover: average minimum and maximum in may (----) and august (-) (redrawn from wadhams 1986). 30' 20" atlantic water is transported northward along the eastern side beyond 80"n, whereas both cold arctic surface water flowing along the western side and deep bottom water are exported south wards into lower latitudes (fig. 3). while the north pacific could be characterised as a more closed and circular system, the north atlantic is an open, asymmetric system with horizontal advection being of great importance for struc turing pelagic systems and, hence, also their sedi mentation patterns. the depth of winter mixing varies regionally with maxima of several thou sands of metres south off iceland and in the central norwegian sea where north atlantic deep and bottom waters are formed. further, there is a large latitudinal gradient of incident light and the nordic seas are characterised by a seasonally variable sea-ice cover i n the west, north and northeast (fig. 2 ) as well as by extensive fronts between arctic water and atlantic water (fig. 3). the regional pattern of the timing a. 'biological spring" depicted in fig. 4 averaged over a 10 year period has been compiled by pavshtiks & timokina (1972). the advent of biological spring is triggered by stabilisation of a shallow surface layer which arises earliest in the southern realm. particularly marked along the norwegian shelf. however, the occurrence of an early spring off the greenland shelf and across the barents sea is related to melting at the ice edge. further north and in the open greenland sea, spring commences as late 2s july/august. the unstable water column northeast of iceland is noteworthy. one would expect the timing of spring dev elopment to have a major influence on sedi mentation patterns. the actual situation, however, is much more complicated. we here discuss vertical flux data from the boreal and polar regions of the northeast atlantic with the aim to identify different factors con trolling the vertical flux. 212 p . wassmann. r . peinert & v . smetacek fig. 3. surface currents and fronts in the northeast atlantic: i = norwegian coastal current: 2 = norwegian atlantic current; 3 = north capc current: 4 = murmansk current: 5 = kanin current: 6 = east spitsbergen current: 7 = west spitsbergen current; 8 = east greenland current: 9 = east icelandic current: 10 = irminger current: 1 1 = jan mayen current. fronts in the northeast atlantic: 12 = norwegian coastal front; 13 = barents sea polar front; 14 = polar ocean front: 15 = east greenland front and iceland gap front. shaded areas = mixing of arctic and atlantic water. case studies northeast atlantic shelf north sea. vertical flux studies were carried out in the fladen ground area of the northern north sea during the springs and early summers of 1976 (flex 76) and 1983 ( r e f l e x 83). striking differences were recorded between these years. during 1976 a spring bloom comprising small diatoms developed and a strong sedimentation pulse consisting of diatom cells and phytodetritus followed (davis & payne 1984). a substantial portion of organic matter produced by this bloom settled o u t . i n 1983 an unusual. small. colonial prymnesiophyte (corymbellus aureus) dominated the spring biomass while diatoms attained only secondary importance (gieskes & kraay 1986). no sedimentation pulse was recorded this year (cadee 1986) and organic material produced by the bloom was apparently retained in the water column. h'orweginn fiords. t h e comp..cated topography of the norwegian coastal zone, which ranges from 58 to 71"n. gives rise to a large variety of fjord, trough and shelf systems. land-locked fjords and open fjords are characterised by different threshold depths at the entrance and different average depths. open fjords and shelf systems are closely connected and house the same plankton organisms. t h e ecology of land-locked fjords, however, differs significantly d u e t o restricted water exchange, the exclusion of various types of plankton and the stagnation of bottom water. a "typical" fjord thus does not exist. seasonal sedimentation trap deployments i n fjords along the norwegian coast revealed dif ferent flux patterns. i n the unpolluted land-locked fjord lindaspollene, for example, major losses were recorded in april and early may with much lower fluxes during the rest of the year (fig. 5a) (wassmann 1983; skjoldal & wassmann 1986). in open fanafjorden in contrast. only little organic fig. 4. timing of “biological spring”. as defined as the beginning of the development of phytoplankton and concentration of c. finmarchicus. euphausiacea. etc. near the surface (pavshtiks & timokhina 1972) in the northeast atlantic. redrawn from pavshtiks & timokhina (1972) with additional information by u . stefinsson (pers. comm.) and k . tande (pers. comm.). production and sedimentation i n the northeast atlantic 2 1 3 roo matter from the diatom spring bloom which occurred in april settled out of the mixed layer within the fjord. t h e bulk of the bloom biomass was probably exported onto the adjacent shelf prior to sedimentation as a result of a wind induced up-welling event. a second phyto plankton bloom, sustained by new nutrients in the newly up-welled water, however, settled out in the fjord itself in may/june. another, minor increase in sedimentation was measured in autumn when water column stability decreased following strong winds (fig. 5a). o p e n fjords could, thus, b e characterised as multi-pulse sys tems (lindahl 1987; wassmann 1991), whereas land-locked fjords with threshold depths lower than the seasonal pycnocline would be single pulse ones. also in the open, subarctic balsfjorden (about 70”n) a seasonality of sedimentation is evident from late winter t o early summer (lutter et al. jul-aug 1989) (fig. 5b). t h e spring maximum following the phytoplankton bloom, however, was much less pronounced compared to fanafjorden. at greater depth seasonal variation was also less significant. this possibly reflects a spring bloom which starts in weakly-stratified waters (eilertsen et al. 1981) a n d , a t the same time, is influenced by the grazing by over-wintering herbivorous zooplankters (hopkins e t al. 1985). the norwegian shelf. t h e few measurements available from the norwegian shelf (fig. 5b) indi cate a spring maximum of vertical flux and low values during summer, i.e. a pattern comparable to balsfjorden and the barents sea. spring trap collections from 1983 (peinert 1986b) contained relatively little intact phytoplankton, indicating that no major phytoplankton sedimentation pulse had been encountered. summer sedimentation rates were lower, less variable and comprised 214 p . wassmann. r. peinert & v . smetacek llndaspollene l 4 0 m ) a 600, d fanallotden 0 norwegian costal current t 0 a-a' a c; vsring plateau (500rn) 0 months fig 5 sedimentation rates of particulate organic carbon (mg c m ' d ' ) in land-locked fjords. open fjords. the norwegian coastal current. the barenrs sea and the vsring plateau data replotted from wassmann (1983. 1984 1989). peinert (1986b). skjoldal & wassmann (19%). lutwr et al (1989). bathmdnn et al (1990a) and wassmann et al (19%)) much less freshly produced matter of phy toplankton origin. t h e bulk of the t r a p collections during this season consisted of krill faeces, some times loaded with tintinnid loricae. the horizontal spring phytoplankton distri bution in t h i s region is very patchy and coupled to the complex hydrography of the norwegian coastal current (braarud et al. 1958; same & mork 1981). frontal processes between the norwegian atlantic current and norwegian coastal current. topographically induced gyres on the shelf (sundby 1984). as well as lateral injections of low salinity water from fjords pro vide variable conditions for phytoplankton growth. differences in water column stability, up/ down-welling, nutrient availability at the onset of the growth season and nutrient replenishment by entrainment influence the immediate growth environment. differences in the initial phy toplankton seeding populations and advection of grazers of different type may modify conditions and hence further contribute t o space/time-dif ferences in the spring bloom. vertical fluxes, accordingly, must b e expected to exhibit a n even greater variability in space/ time during spring as highly non-linear factors influence the direct sedimentation of phyto plankton (nutrient exhaustion triggering mass sedimentation, differing settling behavior of phy toplankters). during spring, maximum vertical flux values may well exceed those depicted in fig. 5b (peinert 1986a), but it may not b e easy t o document such events as they would b e short term and spatially restricted. in general, however, a spring sedimentation pulse of freshly produced autotrophic biomass, based o n and limited by winter nutrients can b e expected regularly o n the norwegian shelf. t h e shelf, because it is shallow, is not a favorable site for the overwintering of large populations of herbivores. t h u s , it has to be colonised by annually dominant grazers during each spring. t h e resultant time lag between spring phytoplankton growth and the onset of intense grazing pressure (mainly by copepods) primarily controls spring sedimentation rates. b a r e n f s sea. t h e amount and seasonality of sedimentation in t h e barents sea is comparable to those of coastal areas of the boreal zone (fig. 5b). highest sedimentation rates of u p t o 1 g c m-* d-' were recorded during a dense phaeocystb pouchetii bloom in areas dominated by atlantic water during may/june (wassmann e t al. 1990). the average sedimentation rate below the euphotic zone ( 5 0 m ) during spring was about 300 mg c m-? d-' (p. wassmann unpubl. data) with significant variation in different areas of the barents sea. during s u m m e r , sedimentation rates were much lower and averaged 80 mg c m-* d ' below the euphotic zone (wassmann 1989). t h e patterns of phytoplankton production and sedimentation in the barents sea are strongly influenced by the seasonal and interannual dynamics of sea ice (rey & loeng 1985). while the southwestern part is always ice-free, the central. eastern and southeastern areas a r e cov ered by sea ice during spring (fig. 2). t h e mar production and sedimentation in the northeast atlantic 215 78-40" 09 time (monlhs) fig. 6. results from a mathematical model by wassmann & slagstad (unpubl. results): seasonal dynamics of primary pro duction (-.-.-.-), sedimentation (-) (g c m-* d ' ) and suspended phytoplankton biomass (-----) ( g c m-*) along a transect in the central barents sea. ginal ice zone moves to the north during summer with the greatest retreat in the eastern barents sea. interannual differences, however, are significant (wadhams 1986). the spring phy toplankton bloom in the southern barents sea dominated by warm atlantic water takes place in may/june (fig. 6c) and is dominated by diatoms, for example chaetoceros socialis. and by p . pouchetii. phytoplankton growth starts already in late march, but stabilisation of a shallow sur face layer by solar insolation is slow in this area and hence phytoplankton biomass increases cor respondingly slowly. a strong pulse of sedi mentation during spring is usually encountered as zooplankton grazing pressure by the major herbivore calanus finmarchicus is light. grazing by this copepod, which also dominates in the atlantic water of the norwegian sea, was shown to counteract sedimentation (peinert et al. 1987). in the southern part of the barents sea, zooplank ton can expect a rather predictable development of the spring bloom during may/june (fig. 6c). to what extent the bloom is influenced by grazing, however, depends both on the size of over wintering populations, especially c . finmarchicus, as well as on the advection of its copepodites from the norwegian sea into the southern barents sea (see below). the southern barents sea is a one pulse system since no additional autumn bloom takes place due to light limitation. in the marginal ice zone further north and east the situation is different (fig. 6a, b). if the sea ice conditions allow for light penetration, the phytoplankton spring bloom starts earlier and develops more rapidly than in the southern rar ents sea. this is due to the rapid increase in stability caused by melting sea ice. again, a strong pulse of sedimenting matter follows the spring bloom after nutrient limitation. if, however, win ter nutrients are left at the end of the spring bloom due to a deterioration of the light conditions (caused by a new advance of the marginal ice zone), another, yet smaller bloom may take place later (fig. 6b). the rapid development of the spring bloom in the marginal ice zone of the barents sea typically decouples phytoplankton development from zooplankton grazing (eilert sen et al. 1989). this effect is most pronounced in the ice-covered north where a minor, light limited spring bloom may take place as late as in august/september during some years, followed presumably by a correspondingly small pulse in sedimentation. in other years, no bloom takes place at all when sea ice covers the northernmost areas until insolation reaches limiting values i n september. annual primary production de creases, thus, with increasing latitude, and food supply is more unpredictable in the northern as compared to the southern barents sea (rey et al. 1987). plant biomass may not be available every year, depending on the ice situation. the major zooplankton species in the areas dominated by arctic water are c . glacialis and calanus hyperboreus, and these species seem well adapted to an unpredictable food supply by a life-cycle of more than one year (tande 1991). this makes them less vulnerable to seasonal and interannual variability in food supply. these copepods are much larger than c . finmarchicus and accordingly produce larger faecal pellets for which higher sinking velocities have to be assumed. it is thus not yet clear if their grazing on spring phytoplankton counterworks sedimentation to the same extent as that of c . finmarchicus. capelin (mallotus oillosus) is a commercially 216 p. wosstmtiti, k. peiriert rr c'. stnetocek important fish that is also a key species in the southern and central barents sea. after spawning close to the coast of northern norway and the kola peninsula. the capelin stocks migrate i n the form of a 'front' northwards into the barents s e a . migrating capelin decimate zooplankton stocks in the southern and central barents sea. leaving behind only sparse numbers in the "wake". con sidering the efficiency with which capelin deplete zooplankton stocks over a bast area (skjoldal & rey 1989). their presence is likely to affect sedimentation patterns. the capelin stocks in the barents sea have been strongly reduced since 1987 as a result of fishing and increased predation by cod. presumably zooplankton at present exerts greater control on the vertical flux than before. as grazing pressure and hence retention of essential elements during summer in the upper layers will have increased due to decreased sedimentation. the present situation in the barents sea might be shifted towards that encountered in the norweg ian sea after the break-down of the herring stock in the sixties (see below). the shallow areas of the barents sea differ from the deeper regions in as much as pelagic herbivores have to share food resources with epi benthic macrofauna. this holds true for the waters especially around bjornoya and spitsber gen as well as in the eastern and southeastern part of the barents sea. locally. some of the world's largest benthic biomass concentrations a r e found here (zenkevitch 1963) exemplifying the tight pelago-benthic coupling characteristic of shallow, arctic environments (grebmeier et al. 1988: hopner-petersen 1989). loss rates of phvto plankton by sedimentation in these areas may be of minor importance when compared t o active removal by benthic suspension feeders. the biodeposition of pelagic suspended matter by the scallop chlaniys islaridica. commonly found in the shallow parts of the barents sea. can locally exceed sedimentation by an order of magnitude (vahl 1980). further, the zooplankton of the banks south of spitsbergen can be dominated by cirripede larvae during may/june ( f . rey pers. comm.) which indicates the important role of this benthic suspension feeder on the plankton of the area. ope11 h'orwegiari sen the surface currents of the norwegian sea are strongly influenced by the warm saline water of the norwegiar, atlantic current whose branches cover a large area of the central northeast north atlantic. in the southwest an additional. arctic water source is supplied by the east icelandic current (fig. 3). o n the norwegian coastal shelf, \vater from the norwegian coastal current con tributes to the northward flow. periods with tem peratures and salinities well below the long-term mean occurred i n the east icelandic current in the late 1960s and were recorded in the 1970s thereafter in the atlantic inflow to the norwegian sea (dickson et al. 197.5; g a m m e l s r ~ d & holm 1984). a down-stream delay of about three years between the rockall channel in the southwest and the entrance t o the barents sea in the north east of the norwegian sea was recorded as well, suggesting that this event was advective (dickson 6: blindheim 1981). this climatic anomaly rep resents one of the most persistent and extensive variations in ocean c!imate yet observed in this century (dickson e t al. 1988) and influences the plnnkton dynamics in the norwegian sea (blindheim 1989). the winter convection in the norwegian sea generally extends to as d e e p as 3 0 0 m and seasonally replenishes near-surface nutrient reserves. as the vernal stratification of the surface layers is almost entirely dependent on solar radi ation. the spring phytoplankton bloom is delayed by one to two months as compared t o the con tinuously stratified coastal waters (halldal 1953; rey 1981). t h e timing of stabilisation. however, varies between years, depending on meteoro logical conditions. the norwegian sea is a transition zone with water sources of both atlantic and arctic origin. accordingly the biota include both boreal and arctic species but, as is typical for northern seas, are not very diverse. t h e spring phytoplankton bloom consists mainly of diatoms. but also years with dominance of naked flagellates were observed. considerable interannual variations in the qualitative as well as the quantitative aspects of the spring development in the norwegian sea have been acknowledged (paasche 1960). t h e summer vegetation is rather sparse and dom inated by microflagellates, coccolithophorids and dinoflagellates. but is more diverse and represents a typical regenerating community. it is not known to what extent autumn blooms take place. the norwegian sea is generally rich in mac rozooplankton with copepods (c. finrnarcliicus, c. hyperboreus), various euphausiids ( e . g . production and sedimentation in the northeast atlantic 217 100 meganyctiphanes noruegica) and pteropods ( l i m acina retrouersa) being important grazers (wiborg 1955). 0stvedt (1955) observed neritic plankton to spread out as far as ocean weather ship m i k e which is well within the norwegian sea proper. there, lie (1968) observed large variations in the timing of maximum zooplankton concentrations (up to three months), possibly also due to advec tion from the norwegian coastal current. advec tion from the norwegian coastal current and also along the axis of the norwegian current results in blurring spatial distribution patterns of arctic and boreal zooplankton. c. finmarchicus maintains itself in the norwegian sea because of ontogenetic vertical migration. the overwin tering population drifts southward at depth whereas feeding stages are moved northwards with surface water (noji 1989). comparing vertical fluxes from oceanic environments of the northeast atlantic with those of the fjords and shelf is difficult because the former are derived from trap deployments below 500m which are greatly reduced due to remin eralization of matter in the upper hundreds of metres. the seasonal sedimentation of poc at 500 m depth on the v ~ r i n g plateau in the norweg ian sea off the norwegian shelf at 67"n is shown in fig. 5c. seasonal maxima were generally found during summer with low sedimentation rates in spring and autumn. three years of trap deploy ments, however, showed significant interannual variations. the single peaks recorded in april 1986 and november/december 1987 appear unexplained. despite the scatter in the data, it is obvious that the "regular" seasonal maximum of vertical flux occurs in summer on the v ~ r i n g plateau and is hence not related to the spring bloom, as is typical for shallow regions described above. microscopic analyses of trap collections indi cate that the various identifiable biogenic com ponents tend to have elevated fluxes at the time of the general seasonal maximum (fig. 7). it appears that sedimentation on the vgring plateau is strongly influenced by zooplankton. through the productive season, zooplankton feeding press ure is high and loss rates, accordingly, are low. the abundance of copepods over-wintering at depth and of those in small numbers present in the surface in late winter and their ability to respond to increases in food supply must be con sidered in order to assess grazer control of the phytoplankton spring bloom in the norwegian p copepod faecal pellets 300 , months diatoms 1490 300 0 300 tintinnids loo 1 forammilera lo\ 0 0 0 0 1 5 pteropods oval faecal pellets 50 mlnipellets 2000 months fig. 7. sedimentation rates at 500 m depth on the vering plateau during 1986 (open circles), 1987 (filled circles), and 1988 (open squares). total flux (dry weight) (mg m-2 d-i) and contributions of different biogenic particles (numbers lo3 m-2 d-i). data replotted from bathmann et al. (1990a). 218 p. wassmann, r. peinert& v. smetacek sea (peinert et al. 1989; bathmann et al. 1990b). spring phytoplankton biomass accumulation and sedimentation thus depends on the grazers and blooms may not take place each year. the trap data, never depicting spring flux maxima in vari ous years indicate in fact that spring phy toplankton outbursts may be the exception from the rule in this region. during summer, a pulse of faecal pellets was observed, presumably due to a declining recycling efficiency caused by ontogenetic migration of c. finmarchicus copepodites to greater depth (bathmann et al. 1987). this event triggered a response in benthic metabolism (graf 1989). indirect evidence indicates that the presence of large copepod stocks counteract pellet sedi mentation, although these are produced in large numbers (smetacek 1980b). the tentative con clusion is that copepods themselves break up their faeces (named coprorhexy by lampitt et al. 1990) and contribute organic material to the microbial network hence promoting recycling of waste prod ucts (smetacek & pollehne 1986). however, repackaging of sinking material can also take place at mid-water depths as reflected by oval faecal pellets and minipellets at certain depth horizons (bathmann et al. 1990a) (fig. 7). detailed microscopy of v ~ r i n g plateau trap samples reveal that not all particles sink out in concert nor are all flux patterns recurrent. the time series (fig. 7) show, for example, that the pteropod flux maximum is in autumn in contrast to the summer maximum of the other biogenic components. although not observed in 1987, the pteropod maximum may nevertheless be a typical feature for the norwegian current as it was found again in 1988 (bathmann et al. 1990a) and was also described for the nearby lofoten basin (honjo et al. 1987). bathmann et al. (1991) show that intense feeding by dense swarms of repro ducing pteropods enhance flux due to sinking out of feeding webs with adhering particles. after reproduction, mass mortality occurred which was reflected in large numbers of pteropod shells i n sediment catches. a shift of the seasonal maximum of the vertical flux towards summer/autumn seems to be typical for the oceanic areas dominated by the norwegian atlantic current (fig. 8a. b) which clearly sep arates them from the coastal and shelf waters of the northeast atlantic. compared to the vsring plateau, the flux maximum i n the lofoten basin (about 650 km northeast of the vsring plateau deployment) occurs even later during autumn (figs. 8 a , b). off bjsrndya, west of the barents sea entrance, sedimentation rates are far higher as in the northeast atlantic proper; seasonality differs and winter values are greatly enhanced (fig. 8a. b). this is explained by winterly sedi ment resuspension and subsequent cross shelf transport of nepheloid layers from the barents sea into the norwegian sea by dense bottom water (midttun 1984; honjo et al. 1988; quad fasel et al. 1988). western regions of the northeastern north atlantic greenland sea and fram strait. the water masses of this region consist primarily of two components: very cold (-1.5 to 1.5"c) and low saline (34.0 to34.6%0) water from the east green land current and slightly warmer and more saline water from the irminger and west spitsbergen currents. the area is heavily covered by sea ice during most of the year, the seasonal and interan nual variability of sea ice, however, is less pro nounced in the fram strait and greenland sea area as compared to the barents sea (fig. 2). sea ice dynamics are dominated by the transpolar current and the east greenland current which transports polar water and ice from the polar sea along the greenland coast into the greenland sea and icelandic areas. the ice cover age is still significant at 60"n in the western part of the northeast atlantic compared to an average latitude of sea ice in the barents sea of about 75"n on the eastern side. heavy sea ice from the polar sea and the fram strait blocks the fjords of east greenland, for example scoresby sound, for most of the year. the productivity of these fjords is, therefore, low. our knowledge about the relationship between plankton production and sedimentation in the fram strait and greenland sea is limited. however, primary production, zooplankton abundance and hence probably also the vertical flux vary much between cold and warm years i n the waters off southern greenland (horsted 1989). primary production is generally highest in the frontal regions between the east greenland current and the warmer water masses. the spring bloom starts in the outer parts of the fjords in southeast greenland as early as march and max ima are found in april and july/august (smidt 1979). microzooplankton has its maximum in july production and sedimentation in the northeast atlantic 219 norwegian atlantic current 0 61-1 (1700m) 8 nb-1 (2815rn) 0. east greenland current c o fs-i (2ooom) p o c gb-2 (1900rn) 0 gb-2 (3000m) 1 '0 j ' f i m ' a l m l j ' j7)a ' s '0 n ' d1 2 0 b o l e i d o f s 1 0 na-1 psi 0 gb-2 ._ c c 0 81.1 a n b l fig. 8. sedimentation rates (mg m-* d-') of particulate organic carbon (poc) and particulate silicate (psi) as obtained from d e e p areas dominated by the norwegian atlantic current and east replotted from honjo et al. 5 1 6 e a (% 12 moored sediment traps in 8 greenland current. data -0. -o-o.o-o-o-o-o j ' f m i a ' m ' j ' j a ' s '0 ' n ' d i (1987). months and the macrozooplankton has a somewhat longer-lasting maximum from june-july onwards. phytoplankton growth in glacial fjords shows a pronounced seasonal cycle and is enhanced in the outer, more mixed areas as com pared to the inner, stratified waters (horsted 1989) where light penetration is lower due to turbidity brought about by the sediment load from glacial meltwater. in the open waters of the davis strait the most important herbivores are the copepods c. fin marchicus, c . glacialis, c . hyperboreus and o. similis. the composition of the zooplankton and the timing of its development are strongly affected by hydrography and ice conditions. c. fin marchicus is an indicator of atlantic water, c. glacialis and c . hyperboreus are characteristic for arctic water, while oithona similis indicates the region of the polar front and mixed waters (pavshtiks 1968). zooplankton development commences during june in coastal waters and in april to may in the davis strait. the timing between primary and secondary production off greenland is coupled to variations of the east greenland and irminger currents that influence ice cover, temperature, and stratification as well as advection of nutrients and organisms. the dis tributions and abundances of for example cod, salmon and shrimps show accordingly long-term and short-term variations (horsted 1989), and so should the vertical flux of particles. polynyas are regularly found in the marginal ice zone off east greenland (niebauer & alexander 1989). the nutrient rich, polar water of the trans polar current is exposed to insolation in these polynyas and the marginal ice zone and is trans ported into open waters (spies et al. 1988). along the drift of water exposed to sunlight, sequences of planktonic developments are found in space which would be found in time at an ice-free, subarctic station. as in the barents sea, diatoms and p. pouchetii are the dominating phyto plankton species (gradinger 1987; smith et al. 1987). ice-algae from melting multi-year ice from the polar basin may add t o the phytoplankton biomass present in polynyas (melnikov & bon darchuk 1987). the zooplankton is dominated by larger forms such as c. finmarchicus, c. hyp erboreus and c . glacialis (barthel 1990; smith & schnack-schiell990); egg production and feeding take place prior t o the spring phytoplankton bloom (smith 1990) and secondary production within the marginal ice-zone can be high (h. j. hirche pers. comm.). the zooplankton com munity shares common features with those of the barents sea as well: atlantic species with annual 220 p. wassmann, r . peinert & v . smetacek life cycles preferring the warmer water to the east of the marginal ice zone predominance (e.g. c. finmarchicus) are contrasted by arctic species in the marginal ice zone and polynyas which prefer colder water and have a multi-annual life-cycle. sedimentation data from these regions are sparse and originate from deep-moored traps. poc sedimentation rates as well as seasonal varia bility i n the greenland basin and the fram strait are lower (fig. 8c) as compared to waters dom inated by the norwegian atlantic current (honjo 1990). sedimentation, however, increases during summer and for biogenic silica one episode of increased vertical flux was encountered by the greenland sea trap (fig. 8d). i t is not known to what extent the ice coverage of the deployment areas during the productive period might have limited primary production and hence sedi mentation. recent deployments including shal lower traps, however, indicate a pronounced seasonal vertical flux pattern (b. v. bodungen pers. comm.). icelandic waters. the hydrography around ice land is influenced by atlantic water from the irminger current and polar water from the east greenland current (fig. 3). whereas atlantic water and the icelandic coastal current dom inate the shelf and oceanic areas t o the south and west of iceland, the waters in the north and east of iceland are influenced by a complicated mix ture of different water masses. the latter area is a highly variable frontal zone fed by the irminger current (atlantic water), the east icelandic cur rent (arctic water), the east greenland current (polar water) as well as the clockwise turning icelandic coastal current (fig. 3). most of the fjords of iceland are deep and well connected to the adjacent shelf. during input of polar water, the marginal ice zone comes close to the northern icelandic coast. low primary production rates were observed dur ing such years and attributed to increased strati fication of surface water, preventing the supply of nutrients from below and hence constraining continued new production (thoradottir 1977). the spring phytoplankton bloom starts in the southern and western waters of iceland in near coastal areas in late march, whereas further in offshore areas its advent is usually in the second half of may (thoradottir 1986). in the north, the spring phytoplankton bloom ends earlier during cold periods than during warmer periods, usually before the middle of june. autumn blooms are generally not reported from icelandic waters. the zooplankton biomass follows that of phyto plankton in the atlantic water and over win tering is of significance in the fjords (astthorsson & jonsson 1988; astthorsson 1990). the spring bloom of the areas to the south and west of iceland is, thus, influenced by grazers. during periods when the influx of atlantic water is strong and the zooplankton stocks are rich, this may probably also be true for oceanic provinces to the north. since new production is lower during times of dominating outbreaks of polar winter, less zooplankton is accordingly found as compared to warmer periods (thoradottir & astthorsson 1984). extensive changes in the physical, chemical and biological properties in the waters have been recorded especially north of iceland, reflecting climatical variations (thoradottir 1977; stefans son & jacobson 1989). while diatoms usually dominate the phytoplankton spring bloom in ice landic waters, colonial stages of p . pouchetii increase markedly during the cold periods. since the 1960s this species has dominated the phy toplankton community t o the north of iceland. the p . pouchetii blooms reflect anomalies in the silicate-nitrate relationship ( s t e f h s o n 1990). to what extent p . poucherii colonies are grazed by zooplankton, sink into the aphotic zone and/or are broken down by microbial degradation is still a matter of dispute (huntley et al. 1987; hansen et al. 1990; estep et al. 1990). however, p. p o u chetii colonies have been observed to sink rapidly in arctic and subarctic waters of the barents sea (wassmann et al. 1990), adding nutrient depletion of the euphotic zone and thus limiting further production in the waters north of iceland. the highly productive front areas off iceland and jan mayen support large zooplankton stocks which have been the basis for large pelagic fish eries (for example herring, capelin and blue whit ing). the herring has played a key role as a planktonic carnivore in icelandic waters and of the norwegian sea (summarised by devold & jacobsen (1968) and dragesund et al. (1980)). herring feed mostly in the waters between iceland, jan mayen and the icelandic gap front during may to september. however, the northern norwegian sea, for example the waters west of b j ~ r n o y a . is also a feeding ground. the herring must have had a pronounced influence on the vertical flux of biogenic matter by grazing on production and sedimentation in the northeast atlantic 22 1 zooplankton and by producing faeces, as fish faeces can contribute significantly to vertical flux (staresinic et al. 1983; heussner et al. 1987). as a consequence of increased stability due to increased supply of cold water from the east greenland current from 1966 on, productivity of the icelandic gap front has since generally decreased (stefansson & jacobson 1989). it can be speculated that climatic induced reduction in zooplankton stocks also resulted in decreased stocks of carnivores as zooplankton resources might be limited in relation to food requirements of zooplankton feeders, for example herring (pavshtiks & timokhina 1972). the effect of the disappearance of herring on other stocks and the zooplankton community is difficult t o assess and so far no observations are available which indicate that the herring has been replaced by any other major planktivore. no vertical flux data are avail able from icelandic waters. we suggest that sedi mentation today is different from that in the mid 1960s and before. evaluation of case studies the case studies clearly indicate that the relation ship between annual patterns of primary pro duction and those of sedimentation can vary considerably. the factors determining vertical flux interact with one another so that flux rates and patterns can exhibit large regional and interannual variability. in the following we exam ine the role of the governing factors individually in order to assess their specific impact on processes governing particle production, modification and sedimentation. nutrients, water column stability and spring phytoplankton growth rate the potential new production is dictated by depth of the mixed layer but also by initial nutrient concentrations. nitrate is generally accepted to be the controlling nutrient species. diatoms and also p. pouchetii blooms respond rapidly when ambient nitrate is exhausted and mass sedi mentation is commonly observed. the deploy ment of ultra-clean methods to monitor essential trace elements has provoked a debate whether iron in particular is the limiting nutrient in some areas of the pacific ocean and the antarctic (mar tin & fitzwater 1988; banse, 1990; martin 1990; dugdale & wilkerson 1990). this debate is beyond the scope of this paper and future results may elucidate a potential impact on the vertical flux of particles. at present, it could only be speculated that, for example, diatoms may respond in a different way to iron limitation com pared to nitrate limitation. aggregation and rapid sinking from surface layers following nitrate limi tation (smetacek 1985) may not be triggered if iron is the limiting element. a shallow mixed layer in spring is a prerequisite for development of the spring bloom. the depth of this layer in relation to light supply determines the rate of biomass accumulation during this period (smetacek & passow 1990). the shal lowest mixed layers are found in sheltered waters but also along fronts between waters of different salinities, for instance on the borders of river plumes and at the edge of melting sea ice. massive blooms covering restricted areas are characteristic of such shallow mixed layers, and blooms cul minate as a result of ambient nutrient exhaustion. these are the blooms most likely to form aggre gates on a large scale that sink out of the mixed layer rapidly (smetacek 1985). the percentage of new production lost t o the system via vertical flux is highest under such conditions. in contrast, spring growth that commences in a deep mixed layer deplenishes nutrients and accumulates bio mass slowly. the impact of grazing is obviously much greater on a phytoplankton population growing slowly as compared t o one growing rapidly. accordingly, the percentage loss via sink ing cells and phytodetritus is smaller and the proportion of organic material channelled t o the grazer pools is larger. however, depending on the degree to which available nutrients are utili sed, total new production can be much higher in regions with a deeper mixed layer, hence also the potential for support. although the average depth of the mixed layer is a characteristic feature of specific regions, it is still dependent on short-term weather conditions. in land-locked fjords, the annual variation will be restricted; in open ocean conditions, variation in the biomass accumulation rate can vary greatly. thus, under cloudy, stormy conditions, mixing will be thorough and average cell division rates low. under the influence of a stable high pressure zone, heating of the upper metres will lead to temporary stabilisation and rapid accumulation of biomass since cells and their progeny will con tinue to divide at maximal rates. one can assume that in such a situation, the thin, warmer water 222 p. wassmann. r . peinert & v . smetacek layers will not lie like a sheet over the colder winter water. rather. the warming water will be susceptible to horizontal displacement and for mation of warm water lenses on the kilometre scale. the horizontal distribution of algal biomass will be correspondingly patchy. indeed, this mechanism is probably responsible for the patchy distribution of the spring bloom recorded in the norwegian shelf by peinert (1986a), along the polar front and in the marginal ice zone of the barents sea and fram strait (h. j . hirche, pers. comm.) and also i n the open baltic during pex 86 (passow 1990). smetacek (1985) postulated that mass flux is preceded by aggregation of cells and chains. aggregate formation in nutrient exhausted blooms has since been observed in nature (kranck & milligan 1988; alldredge & gotschalk 1989; riebesell 1989). it follows that the higher the phytoplankton concentration the greater the speed of aggregate formation and hence also the proportion of the bloom lost to sedimentation. this is the case during blooms of sticky colonies of p. poucherii (wassmann et al. 1990). evidence for such a relationship is circumstantial at present but we see little reason t o suspect that it does not apply in nature. in this case horizontal patchiness of bloom biomass would result in even greater patchiness in vertical flux. composition of phytoplankton sediment trap data to date indicate that diatoms and coccolithophorids both algae equipped with mineral covers contribute a much greater pro portion to vertical flux than flagellates without a mineral burden. this is illustrated by the situation described from the north sea fladen ground in 1976 and in 1983: when diatoms dominated, heavy sedimentation was recorded whereas flux rates were very low when the colonial flagellate corym bellus aureus dominated the spring bloom. the factors responsible for this inter-annual shift in dominance are unknown but their effect on ver tical flux is obvious. the degree to which the latter situation can be classified as unusual also awaits clarification. the fate of another, much more widespread. colonial flagellate (phaeo cystis) appears to be both retention within the mixed layer as well as sedimentation. thus, in the north sea, huge masses of foam emanating from declining phaeocystis blooms accumulate on the coast (batje & michaelis 1986), a phenom enon which never occurs in the case of the larger diatom blooms that precede phaeocystis. we con clude that this flagellate, following senescence of its blooms, does not sink out as readily as do diatoms but, under conditions not yet specified, can indeed settle out of the mixed layer as observed in the barents sea (wassmann et al. 1990). much more information is required on the sinking behavior of different phytoplankton groups and species to further our knowledge of vertical flux. in recent studies in the baltic and the barents sea, passow (1990) and wassmann & rey (unpubl. data), respectively, found significant species-specific differences in sinking behavior within a mixed spring bloom population. the role of grazers as one moves from shallower t o deeper water, the role of grazers increases in importance to an extent that grazing pressure can significantly retard bloom growth and hence prevent sinking out of cells and phytodetritus. whether sedi mentation occurs subsequent t o heavy grazing in the form of herbivore faeces or whether it is retarded altogether depends on the type of grazer dominating this trophic level. protozoans, particularly the large forms that feed by extrusion of a feeding appendage (jakobson & anderson 1986) can well exert significant grazing pressure on phytoplankton including large, chain-forming diatoms. digestion in these organisms seems to be fairly thorough and faeces attributed to this group generally consist of empty frustules. these so-called minipellets can be an important vehicle for transporting whole diatom frustules to the deep sea (gowing & silver 1985; nothig & bodungen 1989). however, we are far from quantifying the role of these organ isms in pelagic systems. their influence on sedi mentation patterns is likely to be substantial and warrants investigation. field data (bathmann et al. 1987; peinert et al. 1987; noji 1989) and laboratory experiments (lampitt et al. 1990) suggest that copepod grazing can counteract sedimentation by keeping matter in suspension. being widespread, more evenly distributed horizontally (for example euphausi ids) and unable to undertake direct horizontal migrations, copepods cannot easily leave their feeding grounds. in this context, coprorhexy (mechanical destruction of their own and other’s faeces; lampitt et al. 1990) and coprophagy are production and sedimentation in the northeast atlantic 223 important mechanisms. by conditioning feeding grounds they would ensure that resources are retained and recycled and not “wasted” by sedi mentation to depths beyond the copepods’ reach. the efficiency of retention would be intimately related to copepod population density and food availability and hence not solely dependent on the immediate growth environment. during spring, copepod over-wintering success, the timing of their ascent from hibernation, population density and grazing pressure in surface waters are factors that exert control on “successful” retention or loss by sedimentation of primary produced matter. this is also supported by a model of phy toplankton growth and sedimentation under vary ing influence of copepod grazing by wassmann & slagstad (unpubl. results). assuming that no zooplankton grazing takes place, the model indi cates that total primary production is solely deter mined by physical factors and sedimentation is high (fig. 9a). if the number of copepods in the model is increased (fig. 9b, c), retention of suspended matter in the upper layers becomes more efficient, sedimentation decreases accord ingly and the phytoplankton biomass maximum is lower as well. biomass of grazers of the copepod type which is controlled by the copepod’s over wintering success and advection during late winter and spring obviously has a dominating influence on the carbon flux in the southern barents sea. as a consequence, grazing pressure can be expected t o be highly variable from year to year, as the maximum macrozooplankton biomass shows a wide range between 1.5 and 15 g c m-2 (skjoldal et al. 1987). grazing by large, roving crustaceans such as euphausiids produces faeces that sink too rapidly for easy recycling at depths of their production. thus these crustaceans inherently deplete their own and others’ feeding grounds. to sustain large fig. 9. results of a model run by wassmann & slagstad (unpubl. results): the effect of zooplankton grazing during early spring (variation in overwintering success and advection) in atlantic water of the barents sea at 72”30’n. the number of copepodite stage v are indicated. primary production sedimentation (-) in g c phytoplankton (----) and zooplankton biomass (.....) in g c m z . (-._._._) and ,,-zd-l. , suspended 15 12 0.9 0.6 u n e 0.3 0 s 0.0 c i b 2000 copepods i c 1.5 & 0 c 20 y 1.2 -10 ................... time (months) n e 0 m i c 0 1 a 0 n c m 224 p. wassmann, r . peinert& v . snietacek populations of this type of herbivore. however, horizontal migration to hitherto ungrazed blooms or continued new production by physical nutrient supply must compensate for losses via sedimented faeces. these organisms, however, also would benefit from copepods and other grazers that recycle matter in near surface layers. other herbivores such as pteropods and some gelatinous plankters (salps. appendicularians) are less predictable i n their appearance. but may be abundant in very high numbers in some years and may significantly influence sedimentation. they all feed efficiently and non-selectively on small particles and, for example, faeces of salps can contribute significantly to the vertical flux (bathmann 1988). discharged pteropod feeding nets (noji 1989) and abandoned appendicularian houses (alldredge 1986) may play a role in accel erating losses by scavenging small and slower sinking particles. finally, the organisms them selves (e.g. pteropods shells) can constitute a seasonally important fraction of settling inor ganics (bathmann et al. 1991). a further and indirect impact on sedimentation, which as yet can only be speculated upon, may result from changes in food web dynamics due to the presence of succession within herbivores. for the open norwegian sea, the maximum sedimentation, as encountered in late summer, could be related to a shift from a food web with copepods as major grazers towards a dominance of pteropods (bathmann et al. 1990a). during years of very high salp abundance, as observed non-periodically and non-predictably in norwegian waters (brattstrom 1972). we specu late that flux patterns would differ from normal years depending on the season of their appear ance: if large salp biomass appeared early in spring, most of the phytoplankton biomass could leave the upper layers due to rapidly sinking faeces. this would leave copepods little chance to increase the size of their population. such a scenario would result in a strong spring pulse in sedimentation and the observed summer or autumn pulse would be greatly reduced. climatic change and the role of advection the fjord examples indicate that advection. dri ven by the local wind field, can determine the annual flux in these coastal systems. i f , for example. the spring advective event referred to above had occurred weeks later, heavy sedi mentation of the phytoplankton bloom could have been expected within the fjord. a second sedi mentation pulse following an upwelling event could have taken place in addition to the first. we can postulate that in such open fjord systems, sedimentation patterns are governed by stochastic events, and hence are highly variable, whereas in closed fjords interannual variation will be lower due to limited advection. i n contrast to the subarctic north pacific, the northeast atlantic on the whole can be viewed as a huge advective flow-through system. the major impact of this large scale latitudinal advec tion along a gradient of physical environmental conditions on sedimentation will be different as compared to the direct influence in the fjords. it is the advection of grazers to latitudes eventually unfavourable for their reproductional success which we believe to be important. the barents sea provides examples of this: the number of copepods advected from the norwegian sea var ies interannually due t o variations of the inflow of atlantic water (blindheim & loeng 1981). the grazing pressure on spring phytoplankton will vary accordingly. long-term changes in the location and strength of major current systems influence the north atlantic as a whole (parsons & lalli 1988). cole brook (1978) and taylor (1978) observed that zooplankton is less abundant when the influence of the north atlantic current on the northeast atlantic is weak. also, periods of hydrographic anomalies in the norwegian and barents seas do have implications for the pelagic food web. as a result of increased stratification due t o a strength ening of the east icelandic current, primary and secondary production has decreased in the ice landic gap front and herring stocks have dis appeared. although fishing was involved in the decline of herring stocks, there is reason to believe that variability in the pelagic system due to changed hydrographical conditions contributed to the observed change as well. a similar dev elopment was observed in the barents sea. here, capelin disappeared as a result of climatically forced changes in zooplankton stock and fishing pressure. the pelago-benthic coupling and the food production for fish is strongly influenced by lateral transport of atlantic water into the southern barents sea (fig. 9) and, thus, subject to climatic variations (blindheim & loeng 1981; skjoldal & rey 1989). the reasons for this varia bility are as yet poorly understood, but we specu production and sedimentation in the northeast atlantic 225 late that the pelago-benthic coupling in the nordic seas may have changed significantly since the decline of the herring and capelin stocks. also, vertical flux may have decreased during recent years since coprophagy and coprorhexy of rich and well-structured zooplankton communities result in retention of food sources in the upper layers. the vertical flux studies accomplished dur ing recent years may, thus, not be representative for previous periods with large abundances of pelagic fishes such as herring and capelin. since the norwegian and barents seas experience large climatic and biological variations, no ‘normal’ pattern of production and sedimentation can be derived from a few annual studies. the dominant copepods in the north pacific differ in their life cycles from those in the atlantic. one school of thought suggests that this difference is the underlying cause for the striking differences in annual cycles of phytoplankton (frost et al. 1983; frost 1987). in the subarctic north pacific gyre, nutrient reserves (nitrate) are never exhaus ted and spring blooms do not occur. this is dif ferent in the north atlantic. an establishment of the pacific copepods in the north atlantic, following from this reasoning, would entirely change its biology towards those patterns observed in the pacific. we tend to believe, how ever, that this would have been ‘tested out’ in the course of evolution and we rather suggest that the cause for the difference lies in the advective nature of the atlantic as compared to the pacific. this different nature of the north atlantic may not allow the establishment of overwintering copepod populations that are tightly geared to the seasonal production regime in the overlying surface layers as in the pacific. colebrook (1985) has pointed out that inter-annual variation in copepod biomass is governed by the size of the overwintering population. peinert et al. (1987, 1989) suggest that this might hold true for the norwegian sea and the model of wassmann & slagstad (unpubl. results) suggest that this is the case for the barents sea as well. if the seasonally first appearing copepods first serve to condition their environment by their activity in such a way as to open and maintain an adequate niche for their progeny, the size of the initial stock would indeed determine reproductive success in that year. such biological gearing within populations and between trophic levels could be affected in unexpected ways by variability of the physico chemical environment. it is the task of future studies to establish such mechanisms and unravel the various processes at work in shaping and driving marine pelagic systems. information on vertical flux will continue to be a prerequisite for furthering our understanding of pelagic systems in this context. acknowledgements. p. wassmann was supported by the norwegian research council for science and the humanities (navf) and the norwegian ministry of the environment. this publication is a contribution from the norwegian research program for marine arctic ecology (pro mare), publication no. 91 of the sonderforschungsbereich 313, university of kiel. and no. 332 of the alfred-wegener-institute for polar and marine research, bremerhaven. references alldredge. a . l. 1986: aggregate dynamics: biological processes. which form, alter and destroy aggregates in the ocean. pp. 109-130 in alldredge, a. l. & hartwig, e. 0. (eds.): aggregate dynamics in the sea: workshop report. american institute of biological sciences, washington d.c. alldredge, a. l . , silver, m. w. 1988: characteristics. dynamics and significance of marine snow. prog. oceanogr. 20,41-82. alldredge. a. l. & gotschalk. c. 1989: direct observations of the flocculation of diatom blooms: characteristics, settling velocities and formation of diatom aggregates. deep-sea res. 36. 159-171. astth6rsson. 0. s. 1990: ecology of the euphausiids thys sanoessa raschii, t. inermis and meganyctiphanes noruegica in isafjord-deep, northwest iceland. mar. biol. 107,147-157. astth6rsson. 0 . s. & jonsson. g. s. 1988: seasonal changes in abundance in isafjord-deep. northwest iceland. in relation to chlorophyll a and hydrography. counc. meet. int. counc. explor. sea 1988fl:3. 18 pp. batje, m. & michaelis. h . 1986: phaeocystis pouchetii blooms in east frisian coastal waters german bight. north sea. mar. biol. 93. 21-27. banse. k. 1990: does iron really limit phytoplankton pro duction in the offshore sub-arctic pacific? limnol. oceanogr. 35, 772-775. barthel, k.-g. 1990: relationships of food uptake and body components of calanus finmarchicus, c . glacialis and c . hyperboreus to particulate matter and water characteristics in the fram strait. polar biol. 10, 34s350. bathmann. u . 1988: mass occurrence of salpafusiformis in the spring of 1984 off ireland: implication for sedimentation processes. mar. biol. 97, 127-135. bathmann. u . , noji, t. t., voss. m. & peinert. r . 1987: copepod fecal pellets: abundance, sedimentation and content at a permanent station in the norwegian sea in may/june 1986. mar. ecol. prog. ser. 38. 45-51. bathmann. u., peinert. r. & bodungen, b. v. 1990a: pelagic origin and fate of sedimenting particles in the norwegian sea. prog. oceanogr. 2 4 . 117-125. bathmann. u., noji. t. & bodungen, b. v. 1990b: copepod grazing potential in late winter in the norwegian sea a factor in the control of spring phytoplankton growth? mar. ecol. prog. ser. 60, 225-233. bathmann, u . , noji, t . & bodungen, b. v. 1991: sedimentation of pteropods in the norwegian sea in autumn. deep-sea res. 10, 1341-1351. 226 p . wassmann, r . peinert & v , smetacek berger. w.. smetacek. v. & wefer. g. 1989: ocean pro ductivity and paleoproductivity. pp. 1-34 in berger, w . , smetacek. v. & wefer. g . (eds.): producfiuify o f f h e ocean: presenf and past. john wiley & sons, new york. blindheim, j . & loeng. h . 1981: on the variability of atlantic influence in the norwegian and barents sea. fiskdir. skr. ser. hauunders. 17, 161-189. blindheim, j. 1989: ecological features of the norwegian sea. pp. 366-401 inrey,l.&alexander.v. (eds.): proc. 6fh conf. com. arcfiquelnternatl, 13-15 may 1986. e . j . brill. leiden. braarud,t.,gaarder. r . k. & nordli.o.1958: seasonalchanges in the phytoplankton at various points of the norwegian west coast. fiskdir. skr. ser. hauunders. 13. 77 pp. brattstrom, h. 1972: on salpafusiformis cuvier (thalaciacae) in norwegian coastal and off-shore waters. sarsia 48.71-90. brewer. p. g., bruland, k. w., eppley, r. w. & mccarthy, j . j . 1986: the global ocean flux study (gofs): status of the u.s. gofs program. eos 67,827-832. cadee, g . c. 1985: macroaggregatesof emiliana huxleyiin sedi ment traps. mar. ecol. prog. ser. 24, 193-196. cadce, g. c. 1986: organic carbon in the water column and its sedimentation, fiaden ground (north sea). nefh. j. sea res. 20.347-358. colebrook. j . m. 1978: continuous plankton records: zooplank ton and environment, north-east atlantic and north sea: 1948-1975. oceanol. a c f a i. 9-23. colebrook. j. m . 1985: continuous plankton records: over wintering and annual fluctuations in the abundance of zooplankton. mar. biol. 84.261-265. davies, j . m. & payne, r. 1984: supply of organic matter to the sediment in the northern north sea during a spring phy toplankton bloom. mar. biol. 78,315-324. deuser, w. g. 1988: variabilityof hydrography and particle flux: transient and long-term relationships. pp. 17s193 in degens, e. t . , izdar, e . i . , honjo. s. (eds.): parficlejlw in the ocean. mitt. geol.-palaont. inst.. univ. hamburg. scope/unep sonderband 62. deuser, w. g . & ross, e . h. 1980: seasonal changes in the flux of organic carbon to the deep sargasso sea. nature ( l o n d . ) 283.364-365. devoid, f. & jacobson, j . 1968: the formation and disap pearance of a stock unit of norwegian herring. fiskdir. skr. ser. hauunders. 15. 1-22. dickson, r . r., lamb, h. h. & malmberg, s. a , , colebrook 1975: climatic reversal in the northern north atlantic. nature (lond.)256,479-482. dickson, r . r . & blindheim. i . 1984: on the abnormal hydro graphic conditions in the european arctic in the 1970s. rapp. p.-u. rdun. cons. i n t . explor. mer 18s. 201-213. dickson. r . r . , meinke. j . , malmberg, s.-a. & lee, a. j . 1988: the 'grcat salinity anomaly' in the northern north atlantic 1968-1982. prog. oceanogr. 22,103-151. dragesund. 0 . hamre, 1 . & ulltang. 0.1980: biologyandpopu lation dynamics of the norwegian spring-spawning herring. rapp. p.-u. rdun. cons. i n t . explor. mer 177.43-71. dugdale, r . c. & wilkerson. f. p. 1990: iron addition experi ments in the antarctic: a reanalysis. global biochem. cycles 4.13-19. eilertsen. h. c . , schei. b. & taasen. j . 1981: investigations on the plankton community of balsfjorden, northern norway. sarsia66, 129-141. eilertsen, h . c.. tande, k. & hcgseth. e. n. 1989: potential of herbivorous copepods for regulating thc spring phytoplan kton bloominthebarentssea. rapp. p.-u. rdun. cons. int. explor. mer 188, 154-163. eppley. r. & peterson, b. j . 1979: particulate organic flux and planktonic new production in the deep ocean. nafure ( l o n d . ) estep, k. w.. nejstgaard, j . c . & skjoldal, h. r. 1990: grazing of copepods upon phaeocystis colonies as a function of the physiological state of the prey. mar. ecol. prog. ser. 67,235 249. frost, b. w., laury, m. r. & hasset. r. p. 1983: feeding behavior of large calanoid copepods neocalanus crisfatus and n. plumchrus from the subarctic pacific ocean. deep-sea res. frost, b. w. 1987: grazingcontrol of phytoplanktonstock in the open subarctic pacific ocean: a model assessing the role of mesozooplankton, particularly the large copepods neocalanus spp. mar. ecol. prog. ser. 39.49-68. gammelsr0d. t., holm, a . 1984: variationsof temperature and salinity at station m (66"n. 2"e) since 1948. rapp. p.-u. rdun. cons. int. explor. mer 185,188-200. gieskes, w. w. c . & kraay, g . w. 1986: analysis of phy toplankton pigments by hplc before, during and after mass occurrence of the microflagellate corymbellus aureus during the spring bloom in the open northern north sea in 1983. mar. biol. 92.45-52. gofs (1989): sediment frap technology andsampling. report of the u.s. gofs working group of sediment trap technology and sampling, woods hole. 93 pp. cowing, m. m., silver, m. w. 1985: minipellets: a new and abundant sizeclassofmarine fecal pellets. j. mar. res. 43,395 418. graf, g . 1989: benthic-pelagic coupling in a deep-sea benthic community. nature ( l o n d . ) 341.437439. gradinger, r. 1986: die phyfoplankfonuerteilung in der fram straj3e zwischen gronland und spitzbergen. diplom thesis, univ. kiel. 94 pp. grebmeier, j . m., mcroy, c . p. & feder, h. m. 1988: pelagic benthic coupling on the shelf of the northern bering and chukchi sea i. food supply and benthic biomass. mar. ecol. prog. ser. 4 8 , 5 7 4 7 . halldal, p. 1953: phytoplankton investigations from weather ship m in the norwegian sea, 1948-49. hualrdd skr. 38. 91 pp. hansen, b..tande. k. & berggreen, u. c . 1990: on the trophic fate of phaeocystis pouchefii (hariot). 111. functional responses in grazing demonstrated on juvenile stages of cal anusfinmarchicus (copepoda) feddiatoms and phaeocystir. j. plankton res. 12,1173-1 187. heinrich, a. k. 1962: the life histories of plankton animals and seasonalcyclesof planktoncommunitiesin theoceans. j. cons. i n f . explor. mer 27,15-24. heussner, s . , monaco, a. & fowler, s. w. 1987: charac terisation and vertical transport of settling biogenic particles in the northwestern mediterranean. pp. 127-147 in degens. e. t.. izdar, e. i. & honjo, s . (eds.), parriclepux in the ocean. mitt. geol.-palaont. inst.. univ. hamburg, scope/unep sonderband 62. honjo, s. 1990: particle fluxes and modern sedimentation in polaroceans. pp. 687-739insmith. w. 0. (ed.): polar ocean ography. academic press, new york. honjo, s., manganini, s. j.. karowe, a . & woodward, b. l. 1987: particle fluxes. north-eastern nordic seas: 1983-1986, woods hole oceanogr. inst. tech. rept. whoi-87-17.85 pp. honjo. s . , manganini, s. j . & wefer, g. 1988: annual particle 282,677-683. 30, 1-13. production and sedimentation in the northeast atlantic 221 flux and a winter outburst of sedimentation in the northern norwegian sea. deep-sea res. 35. 1223-1234. hopkins, c. c. e . , tande, k. s., grbnvik, s . . sargent, j. r. & schweder. t. 1985: ecological investigations of the zooplank ton community of balsfjorden. northern norway: growth. and quantification of condition, in relation to over-wintering and food supply in metridia longa. calanusfinmarchicw, thy sanoessa inermis and thysanoessa raschi. pp. 83-102 in gray, j . s. & christensen, m. e. (eds.): marine biology of polar regions and effecr of stress on marine organisms. john wiley and sons, new york. horsted, s. a . 1989: some features of oceanographic and bio logical conditions in greenland waters. pp. 4 5 6 4 7 6 in rey, l. & alexander, v. (eds.): proc. 6rh conf. c o m . arctique inrernat., 13-15 may 1985. e . j. brill, leiden. huntley, m., tande. k. & eilertsen, h. c. 1987: on the trophic role of phaeocystis pouchetii (hariot). 11. grazing of calanus hyperboreus (krbyer) on diatoms and different size categories of p. pouchetii. j . exp. mar. biol. ecol. 110,197-212. hbpner-petersen, g . 1989: benthos, an important compartment innorthernaquaticecosystems. pp. 162-178inrey. l. &alex ander, v. (eds.): proc. 6rh conf. com. arctiquelnrernat. e . j. brill, leiden. jacobson, d. m. & anderson, j. m. 1986 thecate heterotrophic dinoflagellates: feeding behavior and mechanisms. j . phycol. 22,249-258. koblentz-mishke, 0 . j., volkovinsky. v. v. & kabanova, j . k. 1970: plankton primary production of the world ocean. pp. 183-193 in wooster, w. (ed.): scientific exploration of rhe south pacific, proceedings of the symposium, nat. acad. sci., washington, d.c. kranck, k. & milligan, t. g. 1988: macroflocs from diatoms: in situ photography of particles in bedford basin, nova scotia. mar. ecol. f r o g . ser. 44, 183-189. lampitt, r. s., noji, t. & bodungen, v. b. 1990: what happens to zooplankton fecal pellets? implications for material flux. mar. biol. 104, 15-23. lie, u. 1968: variationinthequantityofzooplanktonandpropa gation of c. finmarchicus at station m in the norwegian sea 1959-66. fkkdir. skr. ser. haounders. 14.121-128. lindahl, 0. 1987: plankton community dynamics in relation to water exchange in the gulmarford, sweden. ph.d. thesis, univ. stockholm. 138 pp. lut1er.s.. taasen,j. p.. hopkins, c. c. e. & smetacek, v. 1989: phytoplankton dynamics and sedimentation processes during spring and summer in balsfjord, northern norway. polar biol. 10,113-124. martin, j. h. 1990: iron in antarctic waters. nature (lond.)345, 156158. martin, j. h . & fitzwater, s. e. 1988: iron deficiency limitsphy toplankton growth in the north-east pacific subarctic. nature (lond.) 331,341-343. melnikov, a. & bondarchuk, l. l. 1987: ecology of mass accumulation of colonial diatom algae under drifting arctic ice. oceanology 27.233-236. midttun, l. 1984: formation of heavy bottom water in the bar ents sea. counc. meer. int. counc. explor. sea 1984/c. 17. 9 pp. niebauer, h. j., alexander, v. 1989: current perspectives on the role of ice margins and polynyas in high latitude ecosystems. pp. 121-144in rey.l. &alexander. v. (eds.): proc. 6thconf. com. arcrique internat., 13-15 may 1985. e. j . brill. leiden. nothig, e.-m. &bodungen. b. v. 1989: occurrence andvertical flux of faecal pellets of probably protozoan origin in the south eastern weddell sea (antarctica). mar. ecol. frog. ser. 56. noji, t. 1989: the influence of zooplankton on sedimentation in the norwegian sea. ber. sonderforschungsbereich 313, u n i u . kiel17. 183 pp. bstvedt, 0. j. 1955: zooplankton investigations from the weather ship m in the norwegian sea. hualrdd. skr. 40.93 pp. paasche, e. 1960: phytoplankton distribution in the norwegian sea in june. fiskdir. skr. ser. hauunders. 12. 77 pp. pars0ns.t. r. & lalli, c. m. 1988: comparative oceanicecology of the plankton communities of the subarctic atlantic and pacificoceans. oceanogr. mar. biol. ann. reu. 1988.317-359. passow, u. 1990. vertikalverteilungund sedimentationvon phy toplanktonarten in der mittleren ostsee wahrend des friihjah res 1986. ber. inst. meereskunde, kiel. 203 pp. pavshtiks, e. a . 1968: the influence of currents upon seasonal fluctuation in the plankton of the davis strait. sarsia 34.38% 392. pavshtiks, e. a. & timokhina, a. f. 1972: history of inves tigationson plankton in the norwegian sea and main results of soviet investigations. proc. r . soc. edinburgh 73,267-278. peinert, r. 1986a: saisonale und regionale aspekte der pro duktion and sedimentation von partikeln im meer. ber. son derforschungsbereich 313, unio. kiel2. 108 pp. peinert, r . 1986b: production, grazing and sedimentation in the norwegian coastal current. pp. 361-374 in skreslet, s. (ed.): the role of freshwater ourfow in coastal marine ecosystems. springer verlag, berlin. peinert, r., bathmann, u., bodungen, b . v. & noji, t. 1987: the impact of grazing on spring phytoplankton growth and sedimentation in the norwegian current. pp. 149-164 in degens, e. t.. fzdar. e. 1. & honjo, s. (eds.): particleflux in fhe ocean. mitt. geol.-palaont. inst., univ. hamburg. scope/unep sonderband 62. peinert, r.. bodungen, b. v. & smetacek, v. 1989: food web structure and loss rates. pp. 34-48 in berger, w., srnetacek, v. & wefer, g . (eds.): producrioity of the ocean: present and past. john wiley and sons, new york. platt, t . , harrison, w. g., lewis, m. l . , li, w. k. w.. sathy endranath, s., smith, r. & vezina, a . f. 1988: biological productionandtheoceans: thecaseforaconsensus. mar. ecol. f r o g . ser. s2.77-88. quadfasel, d., rudels, b. & kurz, k. 1988: outflow of dense water from a svalbard fjord into the fram strait. deep-sea res. 35,1143-1150. rey, f. 1981: the development of the spring phytoplankton out burst at selected sites off the norwegian coast. pp. 649-680 in saetre, r. & mork. m. (eds.): thenorwegian coasral currenr, univ. bergen. rey, f. & loeng, h . 1985: the influence of ice and hydrographic conditionson thedevelopment of phytoplanktonin the barents sea. pp. 49-63 in gray, j. s. & christensen, m. e. (eds.): marine biology of polar regions and effect of srress on marine organisms. john wiley and sons, new york. rey,f.,skjoldal, h. r. ~4slagstad.d. 1987:primaryproduction in relation t o climatic changes in the barents sea. pp. 29-46 in loeng, h. (ed.): the effect of oceanographic conditions on distribution and population dynamics of commercial fish stocks in rhe barenu sea. proc. 3rd soviet-norwegian symp., murmansk, 2 6 2 8 may 1986. institute of marine research, bergen. riebesell, u. 1989: comparison of sinking and sedimentation rate measurements in a diatom winter/spring bloom. mar. ecol. f r o g . ser. 54, 109-119. 281-289. 228 p . wassmann, r . peinert & v . smetacek sztre. r. & mork. m. i y 8 1 : the norwegian coarfal curreri( univ. bergen. 795 pp. skjoldal. h. r. & wassmann, p. 1986: sedimentation of par ticulate organic matter and silicium during spring and summer in lindispollene. western norway. m a r . ecol. prog. ser. 30. 4 9 4 3 . skjomal, h . r.. hassel, a , . rey, f. & loeng. h . 1987: spring phytoplankton development and zooplankton reproduction in the central barents sea in the period 1979-1984. pp. 59-89 in loeng. h . (ed.): the effect of oceanographic condiriom on distribution a n d p o p u l a t i o n d y n a m i c s o f commercial f i h srocks in rhe barenrc sea. proc. 3rd soviet-norwegian symp.. murmansk. 2 6 2 8 may 1986. institute of marine research. bergen. skjoldal. h . r . & rey, f. 1989: pelagicproductionandvariability of the barents sea ecosystem. pp. 2 4 s 2 8 3 in sherman. k. & alexander, l. m. (eds.): biomars a n d geography o f large marine ecosysrems. westview press. boulder. colorado. smetacek, v. 1980a: annual cycle of sedimentation in relation to plankton ecology in western kiel bight. o p h e l i a . suppl. 1 . 65-76. smetacek, v. 1980b: zooplankton standing stock. copepod fae cal pellets and particulate detritus in kiel bight. esruar. coarr. mar. sci. 11.477-490. smetacek. v. 1985: role of sinking in diatom iife-history cycles: ecological. evolutionary and geological significance. m a r . biol. 84.239-251 smetacek. v , brockel. k. v.. zeitzschel, b. & zenk. w. 1978: sedimentation of particulate matter during a phytoplankton spring bloom in relation to the hydrographical regime m a r . b i d . 47.21 1-226 smetacek, v . . bodungen. b. v.. knoppers. b . , peinert, r . . pol lehne. f.. stegmann. p. & zeitzschel. b. 1984: seasonalstage, characterizing the annual cycle of an inshoce pelagic system. repp. p . u . rcun. cons. inr. explor. mer 183. 126135. smetacek. v. & pollehne. f. 1986: nutrient cycling in pelagic systems: a reappraisal of the conceptual framework. ophelia 26.401-428. smetacek. v. & passow, u . 1990: spring bloom initiation and sverdrup's critical depth model. l l m n o l . o c e a n o g r . 35. 2 2 1 234. smidt. e . l. b. 1979: annual cycles of primary production and of zooplankton at southwest greenland. m e d d . g r m l . , bios cience 1 . 1-53. smith. s. l. 1990: egg production and feeding by copepods prior to the spring bloom of phytoplankton in fram strait. green land sea. m a r . biol. 106.59-69. smith. s. l. & schnack-schiel. s. b 1990: polar zooplankton. pp. 527-598insmith. w. 0. ( e d . ) : p o l a r o c e a n o g r a p h y . aca demic press. new york. smith. w. 0.. baumann. m. e. m.. wilson. d. l. & aletsee. l. 1987: phytoplankton biomass and productivity in the marginal icezoneofthe framstraitduringsummerof 1984 1. g e o p h y s . res. 92,87174786. spies. a . , brockmann. u. h. & kattner. g . 1988: nutrient regimes in the marginal ice zone of the greenland sea in summer. mar erol. p r o g . ser. 47. 195-204. staresinic. n . farrington. j . , gagosian. r . b . . clifford. c. h . & hulburt, e. m. 1983: downward transport of particulate matter in the peru upwelling: role of the anchoveta engraulis u p w l l i n g . its sedimenrary r e c o r d . plenum press, new york stefansson. u . 1990: anomalous silicate-nitrate relationships associated with phaeocysris pouchetii blooms. eos 71(2): 77. stefansson. u. &jacobson, j . 1989: oceanographicvariations in the iceland sea and their impact on biological conditions. pp. 427-455 in rey. l. & alexander. v. (eds.): f r o c . 6 t h conf. corn. arcrique inremar.. i s 1 5 may 1985. e . j . brill. leiden. suess. e. 1980: particulate organic carbon flux in the oceans: surface productivity and oxygen utilization. narure ( l o n d . ) . 288.26&263 sundby. s. 1984: influence of bottom topography on the cir culation at the continental shelf of northern norway. fiskdir. skr. ser. hauunders. 17. 501-519. tande. k s. 1991: c a l a n u in north norwegian fjords and in the barents sea. pp. 389-407 in sakshaug. e.. hopkins. c . c . e. & britsland. n. a . (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, 12-16 may 1990. polar research io(2). tay1or.a. h. 1978: long-termchangesin north atlanticcurrent system and their biological implication. proc. r . soc. edin burgh 76.22s243. thbradottir. t . 1977: primary production in northern icelandic waters in relation to recent climatic changes. pp. 655-665 in dunbar. m. j . (ed.): polar oceans. arctic institute of america, canada. thoradbttir. t . 1986: timing and duration of spring blooming south and southwest of iceland. pp. 345-360 in skreslet. s. ( e d . ) : the role of freshwater ourflow i n coarral marine ecos w e m s . springer verlag. berlin. thorad15ttir. t . & astth6rsson. 0. s. 1984: chlorophyll a and zooplankton distribution in icelandic waters in spring 1982. 1983 and 1984. annales biologiques 41.63-66. vahl. 0 . 1980: volume of water pumped and particulate matter deposited by the iceland scallop c h l a m y s islandica in balsfjord, northern norway. pp. 639-644 in freeland, h. j . , farmer. d . m. & levings. c. d. (eds.): fjord oceanography. nato conf. ser. (ser. iv; mar. sci.). new york. wadhams. p. 1986: the ice cover. pp. 21-84 in hurdle. b. g . (ed.): the nordic seas. springer verlag. berlin. wassmann. p. 1983: sedimentation oforganicand inorganicpar ticulate material in lind!ispollene. a stratified, land-locked fjord in western norway. m a r . ecol. p r o g . ser. 13.237-248. wassmann. p. 1984: sedimentation and benthic mineralization of organic detritus in a norwegian fjord. m a r . biol. 83,83-94. wassmann. p. 1989: sedimentation of organicmatter andsilicate from the euphotic zone of the barents sea. r a p p . p . u . rcun. cons inr. explor. m e r 1 8 8 . 108-114. wassmann. p. 1990: relationship between primary and export production in the boreal. coastal zone of the north atlantic. limnol. oceanogr. 35.464-471. wassmann. p . . vernet. m.. mitchell. g . & rey. f. 1990: mass sedimentation of phaeocysris poucherii in the barents sea. mar. ecol. p r o g . ser. 66. 183-195. wassmann. p. 1991: dynamics of primary production and sedi mentation in shallow fjords and polls of western norway. oce anogr. m a r . biol. ann. r e v . 29.87-154. wiborg. k. f. 1955: zooplankton in relation to hydrography in the norwegian sea. fiskdrr. s k i . ser. h a o u n d e r s . 11. 66 pp. zenkevitch. l. a . 1963: b i o l o g y o f r h e s e a s o f the ussr. georgc ringens pp 22-240 i n suess. e & thiede. j (eds ) coarlal allen & unwin ltd , london occurrence of ulva lactuca l. 1753 (ulvaceae, chlorophyta) at the murman сoast of the barents sea research note occurrence of ulva lactuca l. 1753 (ulvaceae, chlorophyta) at the murman сoast of the barents sea svetlana malavenda a, mikhail makarov a, inna ryzhik a, maxim mityaeva & sergey malavendab alaboratory of algology, murmansk marine biological institute, murmansk, russia; bdepartment of biology, murmansk state technical university, murmansk, russia abstract findings of ulva lactuca l. on the murman сoast of the barents sea are described for the period 2009–2017. this species has not been found in this area for more than 50 years. the occurrence of u. lactuca on the murman coast appears to be related to the recent warming of waters in the region. keywords sea lettuce; seaweed; climate change; global warming; arctic; berealization introduction the present study aims to give an overview on the distribution of ulva lactuca linnaeus 1753: 1163 (chlorophyta, ulvaceae) in the barents sea. in the world ocean, this species is very widespread (guiry & guiry 2018), found almost everywhere in shallow waters, including estuaries. the temperature and light tolerance of the species are well studied. photosynthesis has been observed at temperatures ranging from 0°c to 28°c (lüning 1984), with the highest growth rate occurring at 10–15°c (fortes & lüning 1980). at water temperatures of 7°c and 10°c, u. lactuca can adapt to low illumination levels (vermaat & sand-jensen 1987; sand-jensen 1988). however, it is still unclear how u. lactuca responds to the combination of low illumination and low temperature. at the northern margin of its geographical range, u. lactuca findings are random and rare: it has been found on the western, southern and the northern shores of svalbard (vinogradova 1995; gullikssen et al. 1999), novaya zemlya (štrik et al. 2000) and on the coasts of norway (brattegard et al. 2001) and alaska (hayden & waaland 2004; lindeberg & lindstrom 2010). the harsh wintertime conditions of the polar region – low temperature and lack of light (limiting photosynthesis) – is likely the reason for the weak expansion of species in the arctic seas. on the murman coast, u. lactuca was found in olenii strait (22 september 1930), in kola bay (1 june 1932) and in podpakhta bay 30 years later (2 july1961) (vinogradova 1974). species lists compiled later do not mention u. lactuca (e.g., šošina & averintseva 1994; šošina 2003; zavalko & šošina 2008) and even question the presence of this species in the barents sea. analysis of these data indicates the instability of the presence of u. lactuca on the murmansk coast. in recent decades, temperatures in the barents sea have risen following the increased inflow of atlantic water masses during spring (matishov et al. 2009; matishov et al. 2014; mmbi 2017). it is possible that these water masses also brought spores, gametes or zygotes of u. lactuca, which developed in zelenetskaya bay under the more favourable conditions. part of the long-term monitoring of the state of coastal phytocenoses of the murman coast and the russian archipelagos of the barents sea, this study aims to present the latest findings of u. lactuca on the murman coast and to consider their possible relationship with the positive temperature anomalies of the coastal water masses in the barents sea. materials and methods a study of the species composition of the phytocenoses of the murman coast was carried out each year from 2009 to 2017, mainly in the summer (june–september). during this period 12 different sites from pechenga bay in the east (69º 36´ n 31º 21´ e) to ivanovskaja bay in the west (68º 17´ n 38º 44´ e) of the murman coast were investigated, spanning a distance of about 300 km (fig. 1). algae were sampled with a standard geobotanic method, using a frame with an area of contact svetlana malavenda malavenda@yandex.ru murmansk marine biological institute, kola scientific center, russian academy of sciences (mmbi ksc ras), vladimirskaya st. 17, murmansk 183010 russia supplementary data for this article can be accessed here. polar research 2018, vol. 37, 1503912 https://doi.org/10.1080/17518369.2018.1503912 © 2018 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://orcid.org/0000-0002-8314-3255 http://orcid.org/0000-0001-9277-6292 http://orcid.org/0000-0003-3874-2379 https://doi.org/10.1080/17518369.2018.1503912 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2018.1503912&domain=pdf 0.25 × 0.25 m, with three replicas, on the upper, middle and lower littoral. on the entire accessible part of the littoral of the bays, qualitative surveys of species composition were also carried out. ulva lactuca was identified using the description of vinogradova (1974). we relied on morphological features because the genetic analysis of ulva lactuca and another species of ulva gathered in other areas (malta et al. 1999; hayden & waaland 2002; hayden et al. 2004) has shown these to characterize the species. ulva lactuca is characterized by a bright green solid thallus, attached to the substrate by a small rhizoid part (stems and sack-like base are absent). the thallus is bilayered, without a cavity. the cells are arranged chaotically, somewhat elongated in the transverse section, their size ranging from 12 to 23 μm, in most cases 15–20 μm. the chloroplasts are lamellar, in mature thallus, granular. there are one to two (occasionally three) pyrenoids in the cells, but sometimes they are indistinctly visible. differentiation of u. lactuca and u. rigida was not carried out in this study due to the lack of clear species criteria. all the found thalli with the described set of characteristics were considered u. lactuca. ulva rigida has not previously been noted in the barents sea, and we do not consider it reasonable to introduce this species into the flora on the basis of this single sample. further study is needed in order to determine whether u. rigida is present in the region. the material is stored at the murmansk biological institute (murmansk, russia). one of the samples was given to the herbarium of the komarov botanical institute of the russian academy of sciences (st. petersburg, russia). results and discussion murman’s coastal biocenoses were first systematically studied in the period from 1912 through the 1930s. the barents sea underwent a warming in the early 1930s (matishov et al. 2009; matishov et al. 2014), when findings of u. lactuca (vinogradova 1974) on the murman coast were first described. the second period of intensive algological research was from 1985 to the 1990s, when the list of species of yarnyshnaya bay, in the eastern part of the murman coast, was drawn up (šošina & averintseva 1994). at that time, negative temperature anomalies were observed (matishov et al. 2009; matishov et al. 2014) and the species was not on the list. the most recent period in the study of the algal communities of the murman coast began in 2009. thalli of u. lactuca (fig. 2) were found exclusively in zelenetskaya bay (69.10 n, 36.05 e) in 2009, 2012, 2014, 2016 and 2017 (table 1). although zelenetskaya bay had been carefully surveyed in earlier years, 2009 was the first year in which signs of u. lactuca were observed there. in 2009, 2012, 2014 and 2016, single specimens of this species were encountered in zelenetskaya bay, with the first finding being made in the sublittoral community (fig. 1). in 2017, u. lactuca was noted many times on the boulders of the lower littoral, protected from the surf (supplementary fig. s1), and also at the experimental farm of saccharina latissima (linnaeus) lane, mayes, druehl & saunders 2006 and fucus vesiculosus l. 1753. attachment of u. lactuca spores on the ropes of the experimental plot could only happen by way of self-planting from the water column since the thalli of s. latissima and f. vesiculosus, woven into lines, were sampled directly from the bay. the other seaweeds came from the bay, so u. lactica must have landed on the ropes by itself, via the water. in 2016 and 2017, the size of the cells of u. lactuca specimens grown on the farm ropes had smaller cells (7–12 × 12–18 μm, height 14–17 μm), which separates these algae from those grown at the bottom figure 1. the study area on the murman coast. inset: zelenetskaya bay, indicating where ulva lactuca was found in 2009–2017. 2 s. malavenda et al. substrate, although the plants themselves were outwardly typical (supplementary fig. s2). finding u. lactuca in zelenetskaya bay confirms the presence of the species on the murman coast, and adds to observations of the occurence of the species on other barents sea coasts. it also raises a number of questions, since, of all the areas of the murman coast that were surveyed in recent years, u. lactuca was found only in zelenetskaya bay. zelenetskaya bay (in some publications, dal’nezelenetskaya) is protected from the direct action of the surf by a group of islands to the north. the bay shape is square, about 2 km across. depths do not exceed 18 m. the substrate in the protected part of the bay is silty−sandy, with a small amount of medium-sized and small stones, and in the straits and along the edge of the shore there are boulders. there are two inlets in the bay: the south-western inlet (oscar inlet) and a much larger south-eastern inlet. the average annual temperature of the surface waters is 3.8 ± 0.1°c (mitjaev 2014). there are two independent currents in the bay: the waters enter and exit through the western and eastern straits, moving in the inlets counter-clockwise (mitjaev 2014). the hydrological regime of zelenetskaya bay differs even from the adjacent yarnyshnaya bay on account of different physical and geographical conditions (gromov et al. 2010; mitjaev 2014). in 1983–84, the water temperature in the 0–15 m layer of zelenetskaya bay dropped to −1.5°c in january, and a steady rise in the water temperature was observed only from the end of april. in junejuly, the temperature of the water was less than 7°c, and only at the end of august and september was there an increase to 9°c (bardan & širokolobov 1988). since 1998, coastal waters have warmed (matishov et al. 2009; matishov et al. 2014). in 2002–2012, the average annual temperature of the surface water layer in zelenetskaya bay was 3.8°c, and the average monthly temperature in julyseptember exceeded 7°c. in winter, it did not drop below 0.7°c (il’in et al. 2016). oceanographic studies have revealed continuing positive thermohaline anomalies in the spring and summer in 2016 and 2017, indicating the increased inflow of waters of atlantic origin into the barents sea (moiseev & žičkin 2017). observations of a sharp increase in u. lactuca occurrences in zelenetskaya bay in 2017 suggest a relationship with the warming of the bay. it is likely that warmer conditions in the spring and in the first half of summer contribute to the survival and growth figure 2. (a) the appearance of the ulva lactuca thallus found in zelenetskaya bay, july 2017; (b) the transverse section of the thallus, viewed through a microscope. table 1. brief description of the sites in zelenetskaya bay where ulva lactuca was found and the morphological parameters of the specimens. sporangia were present only in the specimen found on 3 august 2016 (marked in boldface). date (dd/mm/yy) site description t (°c) number of specimens thallus size (cm) cell size (μm) 26/08/09 sublittoral, 2 m, bottom community of saccharina latissima 7.2 2 15 × 20 7 × 10 15–20 03/07/12 littoral, bottom community of fucus distichus + f. vesiculosus 7.7 2 3 × 4 4 × 5 15–20 10/08/14 littoral, bottom community of fucus distichus + f. vesiculosus 6.7 1 17 × 15 15–18 03/08/16 seaweed farm (s. latissima), on the rope, near the surface 9.2 1 18 × 25 10–15 13/08/17 lower littoral, an area protected from the violent churning along coastline, between monostroma grevillei at the bottom substrate 7.5 1 1 × 2 15–20 14/08/17 seaweed farm (s. latissima), on the rope, near the surface 8.7 1 6 × 7 12–15 21/08/17 lower littoral of zhiloi island, at the margin of the rockweeds and kelp 9.3 > 20 0.2 × 1–2 × 5 15–20 05/09/17 lower littoral of zhiloi island, at the margin of the rockweeds and kelp 2 2 × 3 and 3 × 4 15–20 polar research 3 of u. lactuca. the ability of this species to reproduce vegetatively in extreme environmental conditions, as well as the viability of zygotes for several months, allows them to spread over long distances (vinogradova 1974). it is probable that u. lactuca zygotes are transported to the study area by the currents coming from the coast of the scandinavian peninsula, and in warmer periods they can germinate and develop. adult plants demonstrate a high tolerance to low temperature (fortes & lüning 1980; lüning 1984; vermaat & sand-jensen 1987; sandjensen 1988); however, the temperature sensitivity of spores, gametes and zygotes of this species has not been investigated. unicellular stages may be more sensitive to stress and are probably unlikely to survive high-latitude wintertime conditions of low temperatures and little light. a similar pattern in the distribution of the species at the northern margin of the geographical range was noted in spitsbergen: studies conducted in 1988 in the southern part of the archipelago – hornsund fjord, sørkappland – did not find this species; but in 2007–08 it was noted (weslawski et al. 2010). the authors attribute the appearance of u. lactuca with the increase in the mean water temperature: the average temperature in hornsund in summer also exceeds 7°c. in the novaya zemlya archipelago, u. lactuca was identified in the collections made in 1994–95 in the yugorsky shar strait, in chernaya bay and at mestnyi island, and in ivanova bay in 1995 (štrik et al. 2000), although the species was not found earlier in this region (gemp & byzova 1976). these findings may be associated with the warming period of the southeastern barents sea in 1990–95 (griŝenko 2010). the findings of u. lactuca in olenii strait and in kola bay in the 1930s and in podpakhta bay in the 1960s (vinogradova 1974) may also be related to climatic conditions of those times (matishov et al. 2009; matishov et al. 2014; mitjaev 2014). thus, the analysis of the periodicity of the findings of u. lactuca in various areas of the barents sea suggests a connection of its recent poleward expansion with an increase of the water temperature. acknowledgements the authors are grateful to t.a. mikhailova for help in transferring material to the komarov botanical institute herbarium disclosure statement no potential conflict of interest was reported by the authors. funding this work was financially supported by project no. rfmefi61616x0073 (memo-pro) funded by the ministry of education and science of the russian federation. orcid svetlana malavenda http://orcid.org/0000-0002-83143255 mikhail makarov http://orcid.org/0000-0001-9277-6292 inna ryzhik http://orcid.org/0000-0003-3874-2379 references bardan s.i. & širokolobov v.n. 1988. gidrologo– gidrohimičeskie issledovanija. (hydrological–hydrochemical research.) in v.g. averincev et al. (eds.): kontrol’ e’kologicheskoj situacii v rajone opy’tno-promy ’shlennoj plantacii v gube dal’nezeleneczkaya (operativny’j informacionny’j material). (control of the environmental situation in the area of the experimental seaweed farm in dalnezelenetskaya bay. operational and information material.) pp. 7–23. apatity: kola scientific center of the russian academy of sciences. brattegard t. & holthe t. (eds.) 2001. distribution of marine, benthic macro-organisms in norway. a tabulated catalogue. research report 2001-3. (updated version of report dn 1997-1.) trondheim: directorate for nature management. fortes m.d. & lüning k. 1980. growth rates on north sea macroalgae in relation to temperature, irradiance and photoperiod. helgoländer meeresuntersuchungen 34, 15–29. gemp k.p. & byzova l.n. 1976. vodorosli proliva karskie vorota (južnoe poberež’e novoj zemli). (the algae of the kara strait, south coast of novaya zemlya.) materialy rybohozaistvennih issledovaniy severnogo bassejna (fisheries research in the northern basin) 12, 102–110. griŝenko v.i. 2010. izmenenija klimata na akvatorii ûgovostočnoj časti barenceva morja. (climate change in the waters of the south-east barents sea.) in g.g. matišov & g.a. tarasov (eds.): priroda šel’fa i arhipelagov evropejskoj arktiki. kompleksnye issledovanija prirody špicbergen. (proceedings of the international scientific conference nature of the shelf and archipelagos of the european arctic. complex investigations of the svalbard archipelago nature. murmansk, russia, 27-30 october 2010.) pp. 68–72. moscow: geos. gromov m.s., moiseev d.v. & ŝirokolobov d.v. 2010 the hydrometeorological conditions in the yarnyshnaya and zelenetskaya bays of the barents sea in the summer of 2009. in g.g. matišov & g.a. tarasov (eds.): priroda šel’fa i arhipelagov evropejskoj arktiki. kompleksnye issledovanija prirody špicbergen. (proceedings of the international scientific conference nature of the shelf and archipelagos of the european arctic. complex investigations of the svalbard archipelago nature. murmansk, russia, 27-30 october 2010.) pp. 72–79. moscow: geos. guiry m.d. & guiry g.m. 2018. algaebase. database maintained by national university of ireland, galway. accessed on the internet at http://www.algaebase.org 1 march 2018. 4 s. malavenda et al. http://www.algaebase.org gulikssen b., palerud r., brattegard t. & sneli j. (eds.) 1999. distribution of marine benthic macro-organisms at svalbard (including bear island) and jan mayen. research report dn 1999-4. trondheim: directorate for nature management. hayden h.s. & waaland j.r. 2002. phylogenetic systematics of the ulvaceae (ulvales, ulvophyceae) using chloroplast and nuclear dna sequences. journal of phycology 38, 1200–1212. hayden h.s. & waaland j.r. 2004. a molecular systematic study of ulva (ulvaceae, ulvales) from the northeast pacific. phycologia 43, 364–382. il’in g.v., moiseev d.v., širokolobov d.v., derjabin a.a. & pavlova l.g. 2016. gidrologičeskij režim guby zeleneckaja, vostočnyj murman. (long-term dynamics of the hydrological conditions of zelenetskaya bay, east murman.) vestnik mstu 19, 268–277. lindeberg m.r. & lindstrom s.c. 2010. field guide to the seaweeds of alaska. fairbanks: alaska sea grant college program. lüning k. 1984. temperature tolerance and biogeography of seaweeds: the marine algal flora of helgoland (north sea) as an example. helgoländer meeresuntersuchungen 38, 305–317. malta e.j., draisma s.g.a. & kamermans p. 1999. freefloating ulva in the southwest netherlands: species or morphotypes? a morphological, molecular and ecological comparison. european journal of phycology 34, 443–454. matishov g.g., berdnikov s.v., zhichkin a.p., dzhenyuk s.l., smolyar i.v., kulygin v.v., yaitskaya n.a., povazhniy v.v., sheverdyaev i.v., kumpan s.v., tretyakova i.a., tsygankova a.e., d’yakov n.n., fomin v.v., klochkov d.n., shatohin b.m., plotnikov v.v., vakulskaya n.m., luchin v.a. & kruts a.a. 2014. atlas of climatic changes in nine large marine ecosystems of the northern hemisphere (1827-2013). international ocean atlas and information series 14. noaa atlas nesdis 78. silver spring, md: national environmental satellit. data, and information service, national oceanic and atmospheric administration, us dept. of commerce. doi: 10.7289/v5q52mk5. matishov g.g., matishov d.g. & moiseev d.v. 2009. inflow of atlantic-origin waters to the barents sea along glacial troughs. oceanologia 51, 321–340. mitjaev m.v. 2014. murmanskoe poberež’e (geologogeomorfologičeskie i klimatičeskie osobennosti, sovremennye geologičeskie processy). (murman coast. geological, geomorphological and climatic features, current geological processes.) apatity: kola scientific center, russian academy of sciences. mmbi 2017. biologičeskie resursy arktičeskih morej rossii: sovremennoe sostojanie, vlijanie prirodnyh izmenenij i antropogennogo vozdejstvija, naučnaja osnova i perspektivy ispol’zovanija. (biological resources of russia’s arctic seas: current state, the influence of natural changes and anthropogenic effects, the scientific basis and perspectives of use for the period 2014-17.) murmansk: murmansk marine biological institute, kola scientific center, russian academy of sciences. moiseev d.v. & žičkin a.p. 2017. termohalinnye uslovija v prikromočnoj zone na severe barenceva morja v aprele 2016 goda. (thermohaline conditions of the ice edge area in the northern barents sea in april 2016.) trudy kol’skogo naučnogo centra ran 8, 10–25. sand-jensen k. 1988. photosynthetic responses of ulva lactuca at very low light. marine ecology progress series 50, 195–201. šošina e.v. 2003. makrofity. (macrophytes.) in l.l. kuznecov & e.v. šošina (eds.): fitocenozy barenceva morâ (fiziologičeskie i strukturnye harakteristiki). (phytocenoses of the barents sea. physiological and structural characteristics.) pp. 177–304. apatity: kola scientific center, russian academy of sciences. šošina e.v. & averinceva s.g. 1994. raspredelenie associacij vodoroslej, vidovoj sostav i biomassa v gube jarnyšnoj barenceva morja. (distribution of the algal community, their species diversity and biomass in yarnyshnaia bay of the barents sea.) in g.g. matišov (ed.): gidrobiologičeskie issledovanija v gubah i zalivah severnyh morej rossii. (hydrobiological research in the bays and coves of russia’s northern seas.) pp. 38–61. apatity: kola scientific center, russian academy of sciences. štrik v.a., vozžinskaja b.v. & vehov n.v. 2000. morskie vodorosli poberež’ja novoj zemli i proliva jugorskij šar. (marine algae of the coast of novaya zemlya and the jugorskiy shar strait.) in a.a. nejman & m.i. tarverdijeva (eds.): morskie gidrobiologičeskie issledovanija. (marine hydrobiological studies.) pp. 88–98. moscow: russian research institute of fisheries and oceanography. vermaat j.e. & sand-jensen k. 1987. survival, metabolism and growth of ulva lactuca under winter conditions: a laboratory study of bottlenecks in the life cycle. marine biology 95, 55–61. vinogradova k.l. 1974. ul’vovye vodorosli (chlorophyta) morej sssr. (ulvaceous algae [chlorophyta] of the seas of the ussr.) leningrad (st. petersburg): nauka. vinogradova k.l. 1995. the checklist of the marine algae from spitsbergen. botaničeskij žurnal 80, 50–61. weslawski j.m., wiktor j. jr & kotwicki l. 2010. increase in biodiversity in the arctic rocky littoral, sorkappland, svalbard, after 20 years of climate warming. marine biodiversity 40, 123–130. zavalko s.e. & šošina e.v. 2008. mnogourovnevaja morfofiziologičeskaja ocenka sostojanija fukusovyh vodoroslej v uslovijah antropogennogo zagrjaznenija (kol’skij zaliv, barencevo more). (multilevel morphophysiological investigation of brown algae, kola bay, barents sea.) vestnik mgtu 11, 423–431. polar research 5 abstract introduction materials and methods results and discussion acknowledgements disclosure statement funding references physical properties, spectral reflectance and thickness development of first year fast ice in kongsfjorden, svalbard sebastian gerland, jan-gunnar winther, jon bone @rba=k & boris v. ivanov a ground truth study was performed on first year fast ice i n kongsfjorden, svalbard, during spring 1997 and 1998. the survey included sea ice thickness monitoring as well as observation of surface albedo, attenuation of optical radiation in the ice, physical properties and texture of snow and sea ice. the average total sea ice thickness in may was about 0.9 m. including a 0.2 m thick snow layer on top. within a few weeks i n both years, the snow melted almost completely, whereas the ice thickness decreased by not more than 0.05 m. during spring, the lower part of the snow refroze into a solid layer. the sea ice became more porous. temperatures in the sea ice increased and the measurable salinity of the sea ice decreased with time. due to snow cover thinning and snow grain growth, maximum surface albedo decreased from 0.96 to 0.74. texture analysis on cores showed columnar ice with large crystals (max. crystal length >0. 1 m) below a 0.1 1 m thick mixed surface layer of granular ice with smaller crystals. i n both years, we observed sea ice algae at the bottom part of the ice. this layer has a significant effect on the radiation transmissivity. s . gerlirtzd, j . -g. winther & j . b . orbcek, norwegian polur institute. polar environmental centre, n-9296 trotns0, nonvayv; b . v. ivunov. arctic and anturc.tic research institute. bering 38, 199397 st. petersburg, russia. introduction many publications (e.g. wadhams 1994) underline the importance of sea ice for climate-related research. climate modelling and remote sensing studies of sea ice rely heavily on ground truth data from field measurements. knowledge of the physical properties and thickness of sea ice and its snow cover are crucial for understanding reflectance characteristics, energy balance, and marine biological productivity. ice thickness measurements from surface, ships or air (e.g. kovacs & morey 1991; wadhains 1994, haas et al. 1997; haas 1998; vinje et al. 1998) usually give snapshot-like information on ice thickness. due to limited accessibility and ice dynamics, it is difficult to obtain time series of ground truth data, including ice thickness and physical properties measured from the surface. especially during melting. optical properties of sea ice have interested researchers for several decades (e.g. langleben 1968; perovich 1994; perovich, roesler et al. 1998). the basic theory and physical principles of radiation measurements over snow-covered ground have been delineated (e.g. wiscombe & warren 1980; warren 1982). spectral character istics of tundra snow before and after the onset of melt in spring in the kongsfjorden area have been published (gerland et al. 1999: winther et al. 1999). the crucial role that svalbard’s seasonally ice-covered fiords play in the biological produc tivity dynamics has also been discussed (e.g. mehlum 1991). for example, sea ice algae survival depends on radiation penetrating the sea ice and the physical and chemical properties of the water below the sea ice and within brine drainage channels (e.g. ackley et al. 1979: homer 1985). this paper describes the changes of fast ice at dyrevika in inner kongsfjorden on the western coast of svalbard at 79”n during the spring melts in 1997 and 1998 (fig. 1). the survey included sea ice thickness monitoring, surface albedo and transmissivity measurements, logging of physical properties of snow and sea ice, as well as texture analysis of sea ice cores from thick and thin gerland et al. 1999: polur research 18(2), 215-282 27s f fig. 1 . map of kongsfjorden showing the research sites dyr and blo. the svalbard archipelago is shown in the inset. the settlement ny-alesund is located at the southern coast of kongsfjorden. most of the studies presented here were performed at site dyr. sections. some work on sea ice in kongsfjorden has been published. carrying out biological studies in kongsfjorden, smith & lydersen (1991) measured snow thickness on the sea ice. there are also published data on the extent of sea ice (spring seasons 1981-83, 1985-86, mehlum 1991; spring 1984; smith & lydersen 1991), showing that the break up of the sea ice cover in kongsfjorden varies between april and july. even as late as in july, these records show dyrevika to be ice-covered, as this place is fairly well protected by the surrounding coast (fig. 1). methods and instrumentation most results presented here originate from mea surements and sampling at site dyr (dyrevika; fig. 1). samples were also taken once in 1997 from the fast ice edge off blomstrandhalvprya (site blo), about 2.5km west of dyr. long-term meteorological records from ny-alesund, some 12km south-west of dyrevika, show a mean annual precipitation of 402.9 mm water equivalent (period 1975-1996), and mean annual temperature of -53°c (1935-1996, fprrland et al. 1997). field work was performed from early may to mid-june. continuous temperature and global radiation data were acquired at dyr with an automatic logging station, using standard thermo meters and pyranometers. dyr was visited about three times a week. we monitored the thickness of snow and sea ice using drilling and snow stakes as well as a portable electromagnetic device (em3 1 , geonics, mississauga, canada). this inductive method enables indirect, fast and non destructive ice thickness determination (kovacs & morey 1991; haas et al. 1997). snow and sea ice temperature was measured with an electronic p t l o o thermometer. snow density was recorded volumetrically using a half-litre tube and a spring balance. we made stratigraphic descriptions of the surface snow layer, including grain size determination, using a magnifying glass and a mm-scale pad. sea ice cores were obtained with a drill that produces cores of about 0.1 m diameter. ice core temperature was measured in holes drilled from the side into the core. core pieces were melted for salinity determination with a standard conductivity meter. from two ice cores we prepared thick and thin sections in the cold laboratory at the alfred wegener institute for polar and marine research. for spectral surface albedo determination we used a portable fieldspec fr spectroradiometer (asd, boulder, usa). it measures over a wave length range from 350 to 2500nm. the field of view for the albedo measurements was 18". the albedo set-up and instrumentation is described in gerland et al. (1999). for the underwater measurements, a waterproof extension fibre was connected to a cosine receptor, mounted on swing arm, which could be operated through drill holes (construction like in mobley et al. 1998). after lowering the sensor in a drill hole, the arm was swung up 90" such that the sensor was positioned a few centimetres below the sea ice and about one metre horizontally away from the drill hole. results meteorozogy: results from the logging station set up at dyr showed that the maximum short-wave global radiation typically vaned from 300 wm-2 (noon) for overcast conditions, which were more common, to 600 wm-2 for clear skies. the average air temperature at dyr remained below 0°c in may, except for short warm periods during the first half of the month each year. the air temperature varied on average between -6 and + 1"c, approaching 0°c at the end of may. in both 276 physical properties, spectral reflectance and thickness development of first year fast ice in kongsfjorden --c snow + ice ' 0 . 4 1 o.2j , 0.0 02/05/97 12/05/97 22/05/97 01/06/97 11/06/97 date 1 .o e $0.6 e 5 2 0.6 y ._ m ._ rn m c c 0.4 t 6 m a y -22may -30may -3june t 9 j u n e -14june -i 0 5 10 15 20 25 30 distance, m years, warm days with average air temperatures up to +2"c and intensive surface melting occurred during the last days of the measurements in early june. integrated short-wave albedo at dyr decreased from around 0.8 in the beginning of may to 0.7 and below at the end of may and beginnifg of june. similar values were measured in ny-alesund, but there the albedo started to decrease later than on the fast ice, probably due to about twice the snow thickness (gerland et al. 1999), and different snow temperatures and metamorphism compared with the sea ice. thickness monitoring: most of the sea ice cover was very even and regular, apart from some encapsulated ice blocks originating from calving events from surrounding glaciers. the average total sea ice thickness in may 1997 was about 0.9 m, of which the top 0.2 m was snow. at the end of may and the beginning of june, the snow layer on top of the ice melted rapidly and almost completely, whereas the ice underneath decreased by only about 0.05 m (fig. 2a). however, samples from drilling showed that, at the same time, the +snow +ice +snow 8 ice i --0snow 8 refrozen laver 02/05/98 12/05/96 22/05/98 01/06/98 11/06/98 date fig. 2. (a) thickness changes of snow and sea ice at dyr in spring 1997. (b) thickness changes of snow and sea ice at dyr in spring 1998 with consideration of formation of a solid refrozen snow layer. the time series from 1998 does not fully include the disappearing of unconsolidated surface snow, because recordings were stopped earlier than the year before for safety reasons. (c) thickness changes from early may to mid june 1997 along a 30 m profile of first year fast ice at dyr, measured by means of electromagnetic induction. the profile follows very even first-year fast ice with only very little spatial thickness variation. the dates of individual profile measurements are indicated. ice became very porous and thus lost strength (see texture analysis below). the development of a solid layer of refrozen snow (see below) at the snow-sea ice interface made it difficult to define exactly the bottom of the snow layer. in 1998, we investigated this more closely and made distinctions between measure ments which both included and excluded the refrozen snow layer (fig. 2b). the initial total sea ice thickness in may 1998 was about 0.1 m less than the year before. this might be connected with the timing variability of onset of sea ice formation in winter. electromagnetic measurements, giving infor mation on spatial variability and changes of total sea ice thickness with time, were taken along a 3 0 m long profile in 1997 (fig. 2c). using a conversion algorithm (haas et al. 1997), total ice thickness was calculated from measured apparent electrical conductivity. the selected profiles show that the first significant thickness changes could be observed on 30 may 1997. the major thickness change is connected to snow thickness reduction, which was also observed by punctual gerland et al. 1999: polar resenrch 18(2), 275-282 277 0.0 0.1 0.2 e 5” 0.3 f g 0.4 a a, -0 0.5 0.6 7 -5 may 1998 -e13 may 1998 -824 may 1998 -a27 may 1998 -&2 june 1998 (a) -o9 june 1998 i i ‘ i ’ i ‘ -3 -2 -1 0 ice temperature, “c 0.0 0.1 0.2 e 50.3 q a, u a, 0.4 0.5 0.6 -5 may 1998 -e13 may 1998 -e24 may 1998 27 may 1998 -2 june 1998 9 june 1998 i i i 5 10 15 salinity, oloo fig. 3. logs from ice cores obtained at dyr in spring 1998 (the dates of individual logs are indicated): (a) temperature, measured in small drill holes in the core, directly after obtaining the core; (b) salinity, measured from melted core sections. direct surface measurements (fig. 2a). a total thickness change (ice and snow) of about 0.2m, derived from electromagnetics, accords with the direct measurements on snow and in boreholes (fig. 2 4 . temperature and salinity: snow and sea ice temperatures rose significantly through spring time. figure 3a shows six selected temperature profiles from ice core measurements from spring 1998. while the logs from may show continuous warming with time, in june the temperature remained rather constant after reaching a certain level. before the onset of melting, salinity measure ments on melted core samples show a typical c shape (fig. 3b), as it is known from other studies on first year sea ice (e.g. clarke & ackley 1984; eicken, lange & dieckmann 1991; perovich, roesler et al. 1998). with warming, the salinity decreased in the upper part of the sea ice, probably due to wicking at the snow-ice interface (see refrozen snow, below) and loss of brine due to enlarged brine channels. snow: as a rule, snow grain sizes increase due to constructive and firnification metamorphosis, whereas precipitation events and destructive metamorphism produce finer grained snow (la chapelle 1992). average grain diameters of the surface snow at dyr increased from between 0.2 and 0.5mm in early may to between 0.75 and 1 mm, occasionally up to 1.5 mm or more. in june, grain sizes in snow below the surface were even bigger, reaching 5 mm and more. i n general, grain size increase reduces surface albedo (e.g. wiscombe & warren 1980). the freeboard (elevation of upper ice edge relative to water level) in early may was between +10 and -20mm; later, after the onset of melt, it decreased to -40 mm. reasons for this change were possibly density increase of surface snow and reduction of absolute ice volume due to melting and increased ice porosity. refrozeti snow: from end of may onwards, we observed a slushy layer at the snow-sea ice interface and also a refrozen, 40mm thick solid “snow” layer, here referred to as “refrozen 278 physical properties, spectral reflectance a n d thickness development of first year fast ice i n kongsfjorden f i g . 3. thin sections from sea ice cores, photographed between crossed polaroids: (a) combination of three vertical sections of mixed surface layer and columnar ice below, showing the upper 0.3 m of the core (18 may 1997. site dyr), (b) horizontal section of columnar ice ( 1 8 may 1997. site dyr), showing relatively large columnar ice crystals, (c) horizontal section of columnar ice (18 june 1997. site blo), showing relatively large columnar ice crystals with high amount of pores. snow”. the existence of those layers (e.g. of the sea ice salinity below. this would indicate ackley et al. 1979; lange et al. 1990; eicken, superimposed ice (e.g. onstott 1992) formed by lange, hubberten et al. 1994; jeffries et al. surface melting, percolation and refreezing. it 1998; sturm et al. 1998) can be crucial for could have been formed i n may. under positive remote sensing interpretation (e.g. onstott 1992). freeboard conditions, and temporal air tempera the salinity of a melted “refrozen snow” sample tures above 0°c (c. haas, pers. c o r n . 1999). in (site dyr, 9 june 1998) was 0.40%0, being 1 1 % contrast, snow-ice, formed after flooding, gen gerland et al. 1999: polar resetirch 18(2), 7-75-32 279 erally exhibits higher salinity than sea ice (eicken 1998). however, we later observed very wet snow in the snowpack’s lower part and negative freeboard, both pointing to flooding. we also observed a positive salinity gradient with depth i n the snow, which indicates sea water wicking (e.g. sturm et al. 1998). these conditions could lead to additional snow-ice formation (lange et al. 1990). texture of sea ice: laboratory texture analyses were performed on thick and thin sections of vertical and horizontal cuts of two sea ice cores. thick sections were inspected on a light table in order to detect pores, brine drainage channels and algae, and thin sections between crossed polaroids for visualization of individual crystals (e.g. gow et al. 1986). a core, taken at d y r on 18 may 1997, exhibited columnar ice with large columnar crystals (length >0.1 m) below a 0.11 m thick mixed surface layer with granular ice and small ice columns (max. crystal length lomm), and a ca. 20mm thick transition zone in between (fig. 4a). horizontal thin sections taken from the columnar ice of the cores from 18 may and 18 june 1997 (retrieved at site blo, ice thickness 0.51 m) show a significant increase i n porosity (figs. 4b, c). sea ice algae: after early may 1997 we observed brownish coloured ice in the columnar ice at the lowest section of the cores. the lowermost 40 mm contained algae, attenuating light significantly more than the ice above (fig. 5 ) . these algae vanished during spring. living in brine channels between the ice platelets that form very young sea ice, the algae disappear in june as the melt begins and associated conditions, such as water salinity, change (m. poltermann, pers. comm. 1999). we observed a maximum in the visible sea ice algae development at d y r during the second half of may. homer (1985) found a similar timing for the beaufort sea. zeebe et al. (1996) modelled the effect of radiation attenuation by an algae bottom layer to be about 90% relative to the incoming radiation above the layer. the algae absorb solar radiation most at wavelengths below 550 nm (perovich, cota et al. 1993). spectral albedo and under-ice solar radiation: a decrease in albedo at d y r and blo during spring (fig. 6a) is mainly due to thinning of the snow cover and snow grain growth. on 18 may 1997, fig. 5. thick section of bottom section showing the darkening of the ice by ice algae ( 1 8 may 1997. qite dyr). the hole in the center of the section was drilled to measure temperature inside the core. the average snow density was 318 kg m-3, whereas the average snow grain size was 2mm. the main part of the snow pack appeared relatively dry with only some liquid water at the snow-sea ice interface. on 3 june 1997, the average snow density was 356kgm-3 and the snow grain size at a fresh thin surface layer was 0.5 mm. below that, snow grains were by then already about 4 m m large. at this stage, the refrozen snow layer formed. on 18 june 1997, melting reached an advanced stage and little snow was left. snow grains reached sizes of 5 to 10 nun, the surface was wet and melt ponds developed. maximum albedo values were about 0.96 on 18 may 1997, while on 3 june and 18 june 1997 they were 0.92 and 0.74, respectively (fig. 6a). interestingly, the change in albedo between 18 may and 3 june 1997 mainly occurred in the visible wavelength range, probably due to the darker ice surface shining through the snow layer, and perhaps also some surface blackening from fine dust from nearby moraines. as spring progressed, the snow became both thinner and more transparent (gerland et al. 1999). from 3 to 18 june 1997, a more pronounced decrease in 280 physical properties, spectral reflectance and thickness development of first year fast ice in kongsfjorden l ' o n . . . . . . . . , 18-may-97 . . . . . . . 03-jun-97 18-jun-97 diff. is-may. 3-jun diff. 3-jun. is-jun 0 u 9 0.4 0.2 0.0 ... 500 1000 1500 2000 2500 wavelength, nm 0.1 wavelength, nm f i g . 6. (a) surface-reflectance studies (albedo measurements) from early (18 may, site dyr, solid black curve), mid(3 june, site dyr, dotted black curve) and late (18 june, site blo. dashed black curve) season 1997. also plotted is the difference in albedo between 18 may 1997 and 3 june 1997 (dashed gray curve) and between 3 june 1997 and 18 june 1997 (solid gray curve) as a function of wavelength. the sky was clear on all three observation days. (b) under-ice radiation measurements, taken at dyr on 13 may 1998. spectral irradiance that reaches the water masses is plotted relative to the irradiance at the surface with snow (dotted curve) and without snow cover (snow was removed, solid curve). the ratio between both curves (dashed curve) is only plotted until 850 nm. irradiance for individual measurements above that wavelength is very low, and the ratio would be mainly affected by instrument noise. visible albedo occurred. even more remarkable was the decrease of near-infrared and infrared albedo during this period, caused by increasing grain sizes and the liquid water in the snow pack. w e performed an experiment measuring under ice irradiance, both with snow on top of the sea ice and also when the snow was removed from the ice (fig. 6b). thus, we were able to distinguish between the attenuation effect from ice and from the combined ice and snow layer. the average snow density was 260kg mp3, with grain sizes varying from 0.1 to 5 mm (smallest grains at the top). the average snow temperature was -2.8"c, and the thickness 0.21 m. the sea ice thickness was 0.61 m, with temperatures from -3.o"c (top) to -1.5"c (bottom; fig. 3a). data were corrected with an immersion correction factor of 1/0.7, which takes different refractions of air and water around the sensors into account. the measurement with snow shows that about 1% of the surface radiation at 550 nm penetrated through the entire snow-sea ice system. after removing the snow, i t became obvious that the snow blocks most o f the radiation. in this particular case 3.7% of the irradiance at 550 nm penetrated the sea ice with a snow cover on top compared to the situation when snow was removed. this relationship was smaller for shorter and longer wavelengths, e.g. 2.3% at 4 0 0 n m and 1.6% at 7 0 0 n m (fig. 6b). infrared radiation penetrates less deeply into the snow pack than does visible radiation. here, this is visualized by the near absence of radiation above 750 nm in the case including snow, whereas a significant portion of ir radiation reached the water masses in the case without snow. conclusions similar ice characteristics observed in two con secutive years indicate that the observed condi tions are rather typical for fast ice in spring in kongsfjorden. the significant reduction of spec tral surface albedo during spring, affected by snow thinning and metamorphism, shows how sensitive the sea ice can be to climate change related processes. moreover, our radiation measurements under the sea ice showed that changes in average snow thickness would heavily affect the amount of optical radiation penetrating the sea ice and thus the amount of radiation available for the ecosys tem in and below the ice. acknow&dgernews. we thank h. miller, h. eicken and c. haas from the alfred wegener institute (awi) for polar and marine research (brernerhaven, germany) for lending us the em31 instrument. c. haas (awi) and m. poltermann (norwegian polar institute, np), helped with instructive dixussions. thin and thick section work was done at awi's cold laboi'dtoiy with support from f. v. delgado (awl). we thank a. blanco (university of helsinki) and 0 . g . s t ~ e n (np) for their help i n the field. this work was performed as part of the project "spectral reflective characteristics of snow and sea gerland et al. 1999: polar research 18(2), 275-282 28 1 ice", within the arctic light and heat (alv) programme, funded by the norwegian research council and np. references ackley. s. f., buck. k. r. & taguchi, s. 1979: standing crop of algae in the sea ice of the weddell sea region. deep-sea res. 26a. 269-28 i . clarke. d. b. & ackley, s. f. 1984: sea ice structure and biological activity in the antarctic marginal ice zone. j . geophys. res. 89(c2), 2087-2095. eicken, h. 1998: deriving modes and rates of ice growth i n the weddell sea from microstructural, salinity and stable isotope data. in m. 0. jeffries (ed.): antarctic sea ice: physical processes, interactions and iariabilit).. antarct. res. ser. 74. 89122. eicken, h., lange, m. a. & dieckmann, g. s. 1991: spatial variability of sea-ice properties in the northwestern weddell sea. j . geophys. res. 96(c6), 10603-10615. eicken, h.. lange, m. a,, hubberten, h.-w. & wadhams, p. 1994: characteristics and distribution patterns of snow and meteoric ice in the weddell sea and their contribution to the mass balance of seil ice. ann. geophys. 12. 80-93. fwland, e. j., hanssen-bauer, i. & nordli, p. 0. 1997: climate statistics and longterm series of temperature and precipitation at svalbard and jan mayen. dnmi (det norske meteorolo giske institutt) klima rapp. 21. 72 pp. gerland, s., winther. j.-g., orbaek, j. b., liston, g. e., (zlritsland, n. a,, blanco, a. & ivanov, b. 1999: physical and optical properties of snow covering arctic tundra on svalbard. hydrol. process. 13(14/1.5). 233 1-2343. gow, a. j., tucker 111, w. b. & weeks, w. f. 1986: crystal structure of fram strait sea ice. crrel special report 86(3// mizex bulletin vii. 20-29. haas, c. 1998: evaluation of ship-based electromagnetic inductive thickness measurements of summer sea-ice in the bellingshausen and amundsen seas, antarctica. cold regions sci. techno!. 27, 1-16. haas. c., gerland, s., eicken, h. & miller, h. 1997: com parison of sea-ice thickness measurements under summer and winter conditions in the arctic using a small electromagnetic induction device. geophysics 62(3). 749-757. homer, r. a. (ed.) 1985. sea ice biota. 215 pp. boca raton. fl (usa): crc press. kovacs, a. & morey, r. m. 1991: sounding sea ice thickness using a portable electromagnetic induction instrument. geophysics .56(1?), 1992-1998. jeffries, m. 0.. li, s., jana, r. a,, krouse, h. r. & hurst cushing, b. 1998: late winter first-year ice floe thickness variability, sea water flooding and snow ice formation i n the amundsen and ross seas. in m. 0. jeffries (ed.): antarctic sea ice: physical processes, interactions and variahilit).. antarct. res. ser. 74, 69-81. lachapelle, e. r. 1992: field guide to sizoii' c q s t a l s . cambridge (uk): international glaciological society. lange, m. a., schlosser, p.. ackley s. f., wadhams, p. & dieckmann. g. s. 1990. ''0 concentrations in sea ice of the weddell sea, antarctica. j. glaciol. 36(12j). 3 15-323. langleben, m. p. 1968: albedo measurements of an arctic ice cover from high towers. j . glaciol. 7(.50), 289-297. mehlum, f. 1991: breeding population size of the common eider somateria mollissima in kongsfjorden. svalbard, 1981-1987. nor. polarinst. skr. 195, 21-29. mobley, c. d., cota, g. f., grenfell, t. c., maffione, r. a., pegau, w. s. & perovich, d. k. 1998: modeling light propagation in sea ice. i e e e trans. grosc.i. remote sens. 36(.5). 1743-1749. onstott, r. g. 1992: sar and scatterometer signatures of sea ice. in f. d. carsey (ed.): microwave remote sensing of sea ice. geophys. monogr. 68. 73-104. perovich, d. k. 1994: light reflection from sea ice during the onset of melt. j . geo/i/zys. res. 99(c2). 3351-3359. perovich, d. k.. cota, g. f., maykut. g. a. & grenfell, t. c. 1993: bio-optical observations of first-year arctic sea ice. geophys. res. lett. 20, 1059-1062. perovich, d. k., roesler, c. s . & pegau. w. s. 1998: variability in arctic sea ice optical properties. j . geophvs. res. 103(ci), 1193-1208. smith, t. g. & lydersen, c. 1991: availability of suitable land fast ice and predation as factors limiting ringed seal populations. phocci hispida, i n svalbard. polar res. 10(2), 585-594. sturm, m . . morris, k. & massom. r. 1098: the winter snow cover of the west antarctic pack ice: its spatial and temporal variability. in m. 0. jeffries (ed.): antarctic sea ice: physical prowsses, interactions and variability antarct. res. ser. 74, 1-18. vinje, t . , nordlund. n. & kvambekk, a. 1998: monitoring ice thickness in fram strait. j . geophys. res. 103(c.5), 1043710449. wadhams, p. 1994: sea ice thickness changes and their relation to climate. in 0. m. johannessen et al. (eds.): the polar oceans and their role in shaping the global environment. geophys. monogr. 8.5, 337-361. warren, s. g. 1982: optical properties of snow. rev. geophys. space phys. 20(1), 67-89. winther, j.-g., gerland, s., 0rbaek, j. b.. ivanov, b., blanco. a. & boike, j. 1999: spectral reflectance of melting snow in a high arctic watershed on svalbard: some implications for optical satellite remote sensing studies. hydrol. process. 13(12/13), 2033-2049. wiscombe, w. j. & warren, s. g. 1980 a model for the spectral albedo of snow. i: pure snow. j . atmos. sci. 37, 21 12-2733. zeebe, r. e., eicken, h., robinson, d. h., wolf-gladrow, d. & dieckmann, g. 1996: modeling the heating and melting of sea ice through light absorption by microalgae. j . geophys. res. l o l ( c l ) , 1163-1181. 282 physical properties, spectral reflectance a n d thickness d e v e l o p m e n t of first year fast ice in kongsfjorden hydrographic and current measurements in the fram strait, august 1981 t o r gammelsrbd and bert rudels g a m e l s r o d , t. & rudels, b. 1983: hydrographic and current measurements in the fram strait, august 1981. polar research 1 n . s . , 115-126. the hydrographic (ctd) observations and pendulum current measurements obtained with m / s 'lance' in august 1981 in the area west and north of spitsbergen, are presented. the warm and saline northward flow, known as the west spitsbergen current, is found to follow the shelf break. in the fram strait the hydrographic structure is complicated because of eddies and other transient movements. the current measurements suggest a two-layer structure where the velocity vector rotates in opposite directions in the two layers with a period near the semidiurnal tidal period. t o r gammelsrfld, geophysical insriture, dio. a . , university of bergen, 5014 bergen-unru., n o r w a y ; berr rudels, norsk polarinstitulr. rolfstangcieien 12, 1330 oslo lufthavn, n o r w a y ; march 1982 (revised o c t o b e r 1982). introduction the passage between svalbard and greenland, the fram strait, is the main connection between the arctic sea and the world oceans. it is very significant as regards the heat and mass exchange in the arctic ocean, and the large quantity of heat carried north by the ocean current influences the climate of the arctic region as a whole. the main positive heat flux through the passage is provided by atlantic water which is transported northward in the west spitsbergen current. almost equally significant in the heat balance is the export of cold polar surface water and ice by the east greenland current (mosby 1962; vow inkel & orvig 1970; aagaard & greisman 1975). a careful study of the heat and water balance requires that the measurements be performed across the whole passage, since a substantial part of the northflowing atlantic water never enters the polar basin proper, but recirculates in the passage (aagaard & greisman 1975; scor working group 58. 1979). in august 1981 the norwegian polar research institute (np) arranged a multidisciplinary expe dition with m / s 'lance' in the svalbard waters. the expedition was in two parts. the first cruise was concentrated in the area north and west of svalbard, while the second was in the northern barents sea. this brief preliminary report deals with the physical oceanography programme in the fram strait as part of a joint project between np and the university of bergen. severe ice conditions in the fram strait pre vented us from extending the stations into the east greenland current. furthermore, due to damage in the ctd cable, the stations after st. 31 extend only to 1650m. this unfortunately reduced the possibility of studying the exchange of bottom water between the greenland sea and the polar basin, which is a subject of considerable interest (aagaard 1981). direct current measurements were obtained in the deeper parts of the passage, but some impor tant stations on the continental slope west of svalbard could not be taken because of poor weather conditions. the positions of the stations are shown in fig. 1. methods vertical profiles (fig. 2 ) of temperature and salinity were obtained using a neil brown ctd sonde lowered at a speed of approximately 1 m/ s. with a sample rate of 30 times per second, this gives a sample approximately every third centimeter. the ctd salinities were standardized against water samples taken with a rosette sam pler attached to the sonde. the bottles were trig gered from the laboratory on board and the ctd values were noted simultaneously from the deck unit. 116 tor gammelsrod & bert rudels 6 0 0 1200 i 8 0 0 2 4 0 0 31100 25.0 25 i 26 0 2 5 . 5 2 1 . 0 2 1 . 5 2 8 . 0 r .;i ( fig. 2 . ctd station 29. the deepest obtained on this cruise. temperature (t), salinity ( s ) and density (&) versus depth are shown. except for a thin surface layer the water column is almost homogeneous fig. 1. map showing the station positions. ctd stations are marked with circles and current measurements with triangles. because of the presence of ice some sections do not follow a straight line. a t station 25 we had t o replace the ctd sonde after it hit the bottom and was damaged. both c t d s seem to have worked well, and when obvious erroneous calibration points were removed we got r.m.s. errors of 0.006% and 0 . 0 0 5 % ~ in salinity. current measurements were obtained from pendulum current meters (haamer 1974). these instruments consist of a plow-shaped wing into which a small plexiglass box is attached. inside the box a compass needle is suspended o n a string and the box is filled with a solution of gelatine, water, sugar and glycol. current measurements were performed by low ering a heavy weight (150-200 kg) on a 6 mm nylon rope, which passes through a meter wheel. t h e current meters were attached t o the rope a t predetermined distances from the weight. about 10 t o 15 instruments were used a t each station. subsurface floats were tied to the rope above the upper current meter and a surface marker was attached. t h e rig was left unattended for about one hour to allow the gelatine solution to stiffen. t h e direction of the current was then determined by the compass needle orientation and the speed by the deviation of the string from the vertical. hydrographic and current measurements 117 the method has several drawbacks, especially when measurements are made in such cold and deep waters as in the fram strait. because of currents the rope may deviate from the vertical, making the observation depths greater than intended. because of the time needed to put out the system, there is also the risk that the gelatine solution will gel either during the actual lowering or while the system is approaching an equilibrium with the current field. to minimize these sources of error, the lowering was made at the highest possible speed; a system could be launched to 3000m in 25-30minutes. to increase the time available for lowering the current meters, the gelatine solution was kept as 'soft' as possible. since it is not possible to determine with cer tainty which observations have been affected by the factors described above, we will proceed as if all measurements giving sensible results are correct, while keeping in mind that uncertainty increases with increasing depth. in spite of these drawbacks, pendulum measurements do provide a simple and easy method of obtaining an instantaneous picture of the current field at a station. the measurements presented here are the deepest so far made with pendulum current meters. the ctd observations the ctd stations (fig. 1) define six sections which are presented here ordered from south to north. the southernmost section along 78"n is pre sented in fig. 3. using the classification proposed by swift & aagaard (1981), we recognize several typical water masses. below 800 m the norwegian sea deep water (nsdw) (t < -.4"c, 34.90%0 < s < 34.94%0) is the dominating water mass (see fig. 3a and 3b). there is a salinity minimum at around 1000 m where the salinity is slightly below 34.90% this cold water mass (t -1°c) is usu ally denoted as greenland sea deep water (gsdw) and is very dense (fig. 3c). at the surface we find polar water (s < 34.4%0) which in summer may reach temperatures of up to +5"c. the atlantic water (aw), defined by t > 3°c and s>34.9%0, is found near the continental slope, sometimes penetrating up onto the shelf. this is demonstrated in fig. 4. the geostrophic velocity field, which is computed assuming no motion at the maximum observation depth, shows that the atlantic water flows northward (fig. 3d). this flow is known as the west spitsbergen current (wsc). on the sections taken farther north, we recog nize the aw which follows the continental slope (see figs. 5 , 6 and 7, and 8). the geostrophic calculations also yield a fairly consistent wsc. in the northernmost section (fig. 8), the aw seems to be colder and less saline than further south. this could indicate that the aw is modified by mixing as it flows northwards, but it is also possible that the current splits up and the main branch is north of st. 76. the water masses in all sections are defined in the description of the section at 78"n. we would like to point out that at the surface on the outer parts of the two northernmost sections there is polar water with temperatures below 0°c. polar water is also found at the bottom of raudfjorden (fig. 8), and is probably produced there during winter. on the two long sections the geostrophic veloc ities computed show a rather 'wiggly' nature (see figs. 3d and 6d). this may be due to eddies in geostrophic balance with a radius of about 30 km. however, internal waves may distort the density field to such a degree that the apparent eddy structure is caused by the non-synoptic nature of the sections. this point is discussed further in the next section, where we present the current measurements. current measurements within the accuracy of the observed directions (* 30"), the observations revealed thick vertical layers with approximately unidirectional flow. the direction and speed of the current in each of these layers were taken to be those found by vertical averaging over the layers. the resulting simplified current field is shown in plan view in fig. 9. the surface currents, which are probably dominated by local winds, have not been included. it must be emphasized that this is a non-synoptic picture, and spans a period of 14 days. the current field on the deeper (>2000 m) sta tions (29-43) has a marked two-layer structure. the thickness of the two layers is 500-1000m. the velocity in a thinner (50-100 m) bottom layer often coincides with that in the lower main layer, but on two stations (29,35) it is in the opposite 118 tor gammelsr~d & bert rudels i . . . fig. 3. contours of (a) tem perature, ( b ) salinity. (c) den sity, and (d) geostrophic veloc ity computed with zero at maximum observation depth based on the ctd section along 78"n defined by stations 3650. maximum observation depths are marked with crosses. hydrographic and current measurements 119 m n 0 0 n n n " m : , * w i " " i ' " ' i ' ~ " l ' ' ' 15 150 225 300 d l s t i k m ) : sect 1 on : s 1 gma t . t i m e : 8 { . 8 . 4 : 7 . 2 5 € 3 3 . 8 . 1: 3 . 4 0 pos: 1 8 . 0 4 ° n 3 . 6 l n w 78.00'n 1 2 . 0 1 ' e along 78 n 120 t o r giinimelsrod 6. bert rrcdels a 0 pl '0 + i z x 0 26 oist. i n k f l : t e m p e r a l u r e i k oeg. c e l . section along 78 78.13" 8 . 9 9 ' e 78.1.3'n 1 3 . 4 9 ' e o a t e l julf 26 2 9 . 1 s b 1 i 2 x p 0 ff,q 4 . samc ;i\ ftg 3 hut b;j,cd o n t h e s e c t i o n along 78"n lion5 > \ b l 4 are ~n the \ame pos ition as 42-50. n o t e the dlfter i ' " ' 1 i 0 so 75 100 dutincd h! s t a t i o n c 1-10. sta o i s t . i n k t l : 26 preicticnl s r l ; n i t y o r t e i j u l y zb 2 9 . 1961 e m scale$ on t h e a x k section r l o n g 76 78.13'n 8.99'e 7 8 . 1 3 ' n 1 3 . 4 9 ' e direction. these deep measurements. however. are rather unreliable (see discussion above). the dicections of flon in the two main layers change considcrabl! from station to station. the observed speeds are rather high 10cm;s and if east-west sections drawn froin stations 36 33 and 3 4 3 (figs. 10. 11) are compared with onl!, a little with d e p t h . the computed geostrophic sections (figs. 6d. 3d), the agreement is poor. neither the magnitude of the current nor the vertical shear show any sig nificant correspondence. t h e current measure ments give a marked two-layer structure on the southern section (fig. 11) with a southward mov ing upper layer above a northward flow in the lower layer. on the northern section (fig. 10) the hydrographic and current rneasitrerrients 12 0 5d 15 2d d i s t . i n k m : c , ., i h g 5 as fig 3 for stations 11-19 direction of flow changes in both layers from station t o station, suggesting the presence of eddies. just as internal waves may distort the density field and affect the geostrophic computations, transient motions such as tides may dominate the current field. with comparatively few stations distributed over such a long period (10 days), it is almost impossible to separate time and space variations and identify mean and transient motions. in order to proceed we make the following hypotheses: (a) semidiurnal tidal motion (m2) is the domi nant periodic motion in the area. (b) the wavelength of the periodic motion is so large that all stations have the same phase. 0 25 prrcticrl s r l i n i t y r 50 1 5 o i s t . i n k h : this permits us to use all stations as o n e time series taken at a single station. tidal motions in broad basins may be described by long gravity waves which are affected by the rotation of the earth. we therefore compute the angular velocity necessary to give the observed change in current direction between the stations. since we are looking for semidiurnal tidal motions, 360" has been added to the observed change of angle if the time difference between two stations is greater than 12 hours. the angle between the currents in the two layers changes from station to station, indicating a baroclinic velocity field. assuming that the velocity vector turns clockwise in the upper layer and counter clockwise in the lower layer, we find that the average angular velocity in the upper layer is w, , , , , c 7 i50 215 dist. in k f l : 15 ceostrophic velocity i n c m i s e c . section rloug 7 9 . 4 78.98.y l . 5 1 ' y 79.67" 10.00'e o r t e i j u l y 3 1 ruwst 3 . 1981 fig 6 a, fig 3 for stations 212-33 35"/h and in the lower layer 26'/h. the reverse situation. with the velocity in the upper layer turning anticlockwise and in the lower layer clock wise. gives the corresponding values. 25"ih (upper) and -23"/h (lower) (see table 1). this should be compared with w / h . which is the average angular velocity for mr. it must be admitted that the scatter is considerable. a pos sible interpretation of these observations is a tide generated baroclinic wave. t h e directions of the orbital motions in the two layers cannot be decided from the data. this is not surprising since 150 d i s t . i n k r : 1 5 prrc tical srlinity sect i o n rlong 7 9 . 4 1 8 . 9 8 ' n 1 . 5 1 ' u 7 9 . 5 7 " i o . o o * e d a t e : j u l y 31 r u g u s t 3 . 1481 ja d i s t . iu k f l : s i f r a t h e t a . section rlong 7 9 . 4 7 8 . 9 8 ' n 1 . 5 1 ° k 7 9 . 6 7 ' n 10.00'e o r t e : july 3 1 rugust 3 . 1 9 8 1 the mean time lag between the stations (-10 h) is close t o t h e semidiurnal period. t h e currents observed on the continental slope and shelf north a n d west of svalbard are stronger and their direction corresponds better with those found from the geostrophic computations. o n the western slope the current is generally to the north (fig. 10) and coincides with the core of saline atlantic water entering the polar basin (see fig. 6). t h e east-west component (fig. 9), on the other hand. shows great variations from station to station. whether these variations a r e generated hydrographic and ciirrent measurements 123 0 u, ,. d -i* y) c 0 -m v1 yi m y l y l y)y) .y1 w v 1 0 t e m p e r a t u r e i n oeg. cel. prriticrl s r l i n i t v s e c t i o n s n e e r e n b u r 80.33" 9 . 9 8 ' e 79-63" 1 k . s z . e s e c t i o n sheerenbur 8 0 . 3 3 " 4 . 9 8 ' e ~ 7 4 . 6 3 " i l 5 2 ' c o r t e : r u w s t 9 l o . ] g a l d r t e : rugust 9 1 0 . 1 4 0 1 y) r 0 olst. i n k n : g e o s t r 0 2 h i c v e l o c i t y i n c h / s e c . s e c t i o n s h e e r e l b u r a 0 . w ~ 9 . 9 8 ' ~ 1 9 . 6 3 0 ~ 1 1 . ~ 2 ' ~ o r t e : rugust 9 l o . 1 9 8 1 s i c n r t h e t r . s e c t i o n smeerenbur 80.33" 9 . 9 e ' e 79.63'n i 1 . s z ' e d r t e : r u w s t 9 i d . 1981 fig. 7. as fig. 3 for stations 53-65. a l3 1 0 0 0 1 5 1 . i n fin: t e m p e r r t u r e i n oec. c e l . section r r u o n e f o 8 0 . 5 8 . n 1 1 29.e ~ 19-67" 1 z . l l ' e orle: rucusl 1 0 1 1 . 1 4 8 1 i p r r c t i c r l s r l i n i t y 5 c c t i o i i rruonefo 8 0 58.m i 1 29.e ~ 79 61" 1 2 . 1 1 ' € orle. rugus1 1 0 ~ , i . 1 4 8 1 fig. 8. as fig. 3 for stations 66-76 124 tor g a n i n i e l s r ~ d & bert rudels 81c 8 0 72 70o l o o o d l o o i hfi % 7 7 fig. 9 pendulum current measurements. vertical layer mcans. see text n o r t h c o n p 7 5 f 'f 73 0 0 100 11 51 30 29 2 0 2 1 26 ~ , ~ l o o o rn 1000 2 0 0 0 0 k m 50 100 150 200 7 t 81 80° 7 q 0 7 8 o a g . 10. contours of north com ponent of current hased o n measurements at stations 2 6 34. hydrographic und ciirreiii measurenienis 125 35 s t 30 lo l i l ? l 3 200u n o r t h comp k m 50 100 i 5 0 200 fig. 11. as fig. 10 for stations 35-43. table i. the change in direction of the currents i n the two layers o n stations 29-43. for explanation. 5ee text. station a i @upper a 0 upper b upper h lower a @ lower ti lower h degrees degrees o/h degrees degrees o/h anticvclonic rotation in upper 29 260 30 10 210 31 1 n 230 32 8 15 33 6 0 34 4 295 35 20 200 38 30 260 40 9 230 41 5 135 42 5 185 43 6 1 50 laycr -310 -20 145 -345 295 -(265 + 360) -(60 + 2.360) 330 265 5 0 325 -31 0 -2.0 -18.1 -57.5 -73.8 -31.3 -26.0 -36.7 -53.0 -10 0 -54.2 160 325 1 61) 260 245 315 315 305 340 50 10 t 195 t 165 t 260 i5 +(290 t 360) + ( @ t 2.300) + 10 +325 + ? y o t 40 t 19.5 t i h . 5 t 3 2 . 5 t 2 . 5 +27.0 i 2 4 . 0 r 1 . l t 65.1) + 5 8 . 0 + ( i 7 __ __ -35 x 25.3 ~~ ~~ station a t bupper ah upper @ upper 0 lower a 8 lower r lower h degrees degrees o ‘h degrees degrees oi h cyclonic 29 30 31 32 33 34 35 38 40 41 42 43 rotation i n upper layer 260 10 210 10 230 8 15 6 0 4 195 20 200 30 260 9 230 5 135 5 1x5 6 150 50 340 215 15 65 (95 + 360) (300 t 720) 30 95 310 35 5.1 34.0 26.9 2.5 16.2 21.8 34.0 3.3 19.0 62.0 5.8 21.1 160 325 160 260 245 315 315 305 340 50 10 165 195 100 -345 -(70 t 360) (0.720) 350 35 70 320 -16 5 1y.5 12.5 5 7 . 5 -17 y -24 0 -38 9 -7 0 -14.0 -53.3 -26 1 __ 126 tor gammelsrad & bert rudels east comp 53 51 56 5 8 i , , , , , , i i i , 1 , i i t ’ ’ 0 k m 2 5 50 7 5 fig. 12. contours of east component of current based on measurements at stations s 5 8 . locally by the bottom topography, or are due to transient motions, cannot be decided from so few data. on the north-south sections north of svalbard (figs. 12, 13) we find a relatively strong (10 lscm/s) and persistent flow towards the east. these observations show that the atlantic water present on the shelf moves east north of svalbard as it enters the polar basin. this agrees with the classical observations made by nansen (1915), sverdrup (1933), and mosby (1938). summary our measurements show a complicated structure in the waters and motions in the fram strait. it c t 500 i i ! 1---1-i ’ ’ i ’ 4 0 k m 2 5 5 0 fig 13 as fig. 12 for stations 71-75 is a region where 4-5 different water masses meet and mix and perhaps new water masses form. the simple inflow-outflow current pattern is compli cated by baroclinic tides and probably by strong eddy motions. to reasonably resolve the structure in the passage would require a much greater effort than the present one. the warm and saline west spitsbergen current is revealed both by ctd measurements and direct current measurements. it follows the shelf break, turning east north of svalbard. acknowledgements. we express our gratitude to the crew on board the m/s ‘lance’ for their great help and interest in our work. bruce hackett is acknowledged for his critical review of an early version of the manuscnpt. torgny vinje organized our participation on the cruise and arne foldvik contributed with stimulating suggestions. one of us (br) was supported by the nordic council of physical oceanography. references aagaard, k. 1981: on the deep circulation in the arctic ocean. deep sea res. 28a. 251-268. aagaard, k. & greisman, p. 1975: towards new mass and heat budgets for the arctic ocean. j . geophys. res. 80, 3821 3827. haamer, j. 1974: current measurements with gelatine pen dulum. vanen no. 1 . mosby, h. 1938: svalbard waters. geofysiske publikmpner xi1 ( 4 ) . mosby, h. 1962: water, salt and heat balance of the north polar sea and of the norwegian sea. geophys. publ. 24, 28!+313. nansen, f. 1915: spitsbergen waters. oceanographic obser vations during the cruise of the ‘veslem~y’ to spitsbergen-in 1912. vid. selsk. skr. i . matem.-naturuit. ki. 1915 no. 2. christiania. scor working group 58, 1979: the arctic ocean heat budget. rep. no. 5 2 , geophysical institute, div. a , univ. of bergen, norway. sverdrup, h. u . 1933: oceanography. scientific results of the ‘nautilus’ expedition 1931. part 11. pupers in phys. ocean. and met. i1 (1). cambridge, mass. swift, j . h . & aagaard, k. 1981: seasonal transitionsand water mass formation in the iceland and greenland seas. deep sea res. 28, 1107-1130. vowinkel, e. & orvig, s. 1979: the climate of the north polar basin. in orvig, s. (ed.): climates of the polar regions. world survey of climatology 14. elsevier. 370 pp. heygster.indd 35voss et al. 2003: polar research 22(1), 35–42 improving sea ice type discrimination by the simultaneous use of ssm/i and scatterometer data stefan voss, georg heygster & robert ezraty the multi-year sea ice (my) concentration as determined with the nasa team algorithm (nta) shows an increase during winter. this unrealistic feature can be reduced using combined active and passive remote sensing data, leading to a more realistic estimation of my area. our joint analysis of ssm/i, quikscatterometer (qscat) and meteorological data reveals events (i.e. intervals in space and time) where increased surface roughness and volume scattering, after a melt–refreezing episode, alters the passive microwave signature of the undisturbed sea ice surface. in these events, the calculation of my and fy areas employing the nta leads to false estimations of their amounts. it is shown that when such events occur, qscat backscatter values increase by more than 3 db. this backscatter variation can be easily detected and the fy and my area determination of the nta can be corrected accordingly within defi ned event–regions. using this method, called simultaneous nta, we found that in may 2000 12 % of the area detected by the nta as my has to be corrected to fy. as a consequence, a detailed reanalysis of the 20-year passive microwave data set is suggested to more precisely compute the my area. s. voss & g. heygster, institute of environmental physics, university of bremen, box 330440, d-28334 bremen, germany, heygster@uni-bremen.de; r. ezraty, institut français de recherche pour l’exploitation de la mer, centre de brest, bp 70-29280 plouzané, france. in the context of climate scenarios, perennial sea ice volume is a major prognostic parameter used by modellers to detect long-term warming trends in the arctic. when used for control purposes, this parameter is in practice reduced to multi-year sea ice (my) extent obtained from micro wave satellite measurements because of the scarcity of sea ice thickness measurements. the multi frequency bright ness temperature (tb) data of the scan ning multichannel microwave radiometer (smmr) and the later special sensor microwave/imager (ssm/i) are used to calculate the ice concentra tion (the percentage of ice-covered ocean). analysis of this data over the period 1978–1997 reveals a reduction of about 3 % per decade in total ice extent (parkinson et al. 1999; serreze et al. 2000). but it has remained unclear whether the amount of my (ice having survived at least one summer season) has changed. on average, my is about three times thicker than fi rst-year ice (fy)—which is typically 1 2 m thick—so that changes in ice type distribution are important climate change indicators. evidence of a long-term trend of the sea ice cover has been presented by johannessen et al. (1999) by analysing time series of my areas from 1979 to 1998, based on smmr and ssm/i data (see their fig. 1). on the one hand, this fi gure shows a trend of 14 % reduction of the my area during this 19-year period. on the other hand, during the winter period, a large increase in my is shown, which is unrealistic since all increase is fy. kwok et al. (1996) have shown that the variability in my during winter appears to be caused by spatial and temporal variations in the signatures assumed constant in the algorithm, but they 36 improving sea ice type discrimination did not identify the responsible geophysical processes. my, fy and open water have different radiative properties. the nasa team algorithm (nta) developed for the smmr instrument (gloer sen et al. 1992) and later revised to be used for the ssm/i data (cavalieri et al. 1991) is able to separate each of these surface types and estimate the fy and my concentrations (cfy and cmy) in the cold season. although the total ice concentrations (ct) estimated as cfy + cmy seems realistic, sudden, unrealistic variations of opposite sign in cfy and cmy time series have limited the confi dence in these estimates. the purpose of this paper is to show how the use of independent external information, namely the variations of backscatter measured by a scatterometer, can be used to identify the intervals in time and space (hereafter “events”) when passive radiometer measurements will lead to a false my concentration value. the data sets and the basic parameters used are presented in the following section. we then discuss an illustrative example of an event, after which we present the method used to detect systematically these events and then correct the ice concentration. the data sets the radiometric data and the nta since 1987, the ssm/i radiometer onboard the usa’s defense meteorological satellite program satel lite series measures brightness temperatures at different frequencies and polarizations (v polarization and h polarization) at a constant incidence angle of 53° (hollinger et al. 1990). the nta makes use of the channels measuring at 19 ghz vertical and horizontal polarization (19 v, 19 h) and at 37 ghz vertical polarization (37 v). the data are processed and mapped onto a 25 × 25 km2 polar stereographic grid prepared by the national snow and ice data center (nsidc). the algorithm exploits the large brightness temperature dif ference of open water and ice between the 19 v and 19 h channels. furthermore, the tb difference between 37 v and 19 v is greater over my than over fy. these properties are expressed in the form of two independent variables: the polarization ratio (pr) and the gradient ratio (gr) defi ned as: pr = [tb(19 v) – tb(19h)] / [tb(19 v) + tb(19 h)] gr = [tb(37 v) – tb(19 v)] / [tb(37 v) + tb(19v)] which are the input quantities to the algorithm. using ratios of tb reduces the errors due to surface temperature variations. pr is mainly sensitive to ct while gr varies with the fractions of fy and my (see fig. 2.3.5 in gloersen et al. 1992). reference tb (tie points) defi ne, in the prgr diagram, the location of 100 % cfy , 100 % cmy and open water. once the percentage of each ice type is computed, ct is estimated as: ct = cfy + cmy . the scatterometer data and the meteorological data scatterometers have been originally constructed for wind vector retrieval over the ocean. yet it has been shown that they provide useful information on sea ice type and extent (gohin & cavanié 1994; ezraty & cavanié 1999; bingham & drinkwater 2000). a scatterometer emits an electromagnetic pulse and measures the backscattered signal. the normalized radar backscatter σ0, defi ned as the ratio of scattered power relative to isotropic scattering targets, is characteristic for the scattering target. in this study, data from the seawinds sensor of the quickscatterometer mission (qscat) are employed. qscat operates at 13.4 ghz (ku-band) and has two beams at constant incidence angles of 46° and 54° with h and v polarization, respectively. a detailed description of the sensor, the data processing and the fi nal daily backscatter maps can be found in ezraty & piollé (2001). these maps use the same polar stereographic projection and the same grid size as used by nsidc for the ssm/i data. this facilitates comparative and simultaneous studies involving both sensors. in this study, the backscatter maps of the inner beam (h polarization) are used because the dynamic range is higher at the lower incidence angle, and the backscatter signal does not depend signifi cantly on the polarization of the incident radation (ezraty & cavanié 1999). information about the weather conditions in the regions of interest is obtained from coastal weather stations. maximum and minimum temper atures and the amount of precipitation are extrac ted from the website of wetteronline gmbh (2001). 37voss et al. 2003: polar research 22(1), 35–42 joint analysis of ssm/i, qscat and meteorological data for a selected event this section shows the simultaneous use of data collected by the active and passive microwave instruments together with meteorological information. the two example areas presented here lie off the east coast of greenland at the latitude of iceland (area ca. 300 × 250 km2) and in hudson bay (ca. 250 × 250 km2) (fig. 1). the meteorological conditions measured at the met eorological station of tasiilaq (65.6° n, 37.6° w) and kuujjuarapik (55.2° n, 77.5° w) are assumed to be representative of the whole of the two areas. high backscatter events during the arctic winter, typical σ0 values for fy are between –18 db and –11 db, those of my are above –11db (voss 2002). the threshold of –11 db is similar to the seasonally slightly varying values found by kwok et al. (1999). nevertheless, discriminating fy and my on the basis of a fi xed σ0 threshold is frequently found incorrect in small areas (80 to 500 × 103 km2) showing fig. 1. map of area showing areas of open water, multiyear sea ice and fi rst-year ice. investigated areas near tasiilaq, greenland (1), and near kuujjuarapik (2), hudson bay, are marked. fy where events are detected from october to may, 1999–2001 first-year ice (fy) with σ0 < –11 db multi-year (my) sea ice open water 38 improving sea ice type discrimination a high σ0 within ice known to be fy. the time series of the mean σ0 over the event area marked as number 1 in fig. 1 is shown in fig. 2a. twice during the investigated period, σ0 increases by about 4 db within 2 4 days. the beginnings of the σ0 increases—the “events” (3 february 2001 is event 1 and 20 april 2001 is event 2)— are marked with a vertical bar. the maximum is fig. 2. (a) time series of daily qscatσ0 data averaged over the test area off tasiilaq, greenland, during 2001 (thick solid line), the daily maximum temperature (tmax: thin solid line), minimum temperature (tmin: dotted line), and the amount of precipitation (histogram). (b) time series of qscat-σ0, pr and gr; r is the correlation coeffi cient between σ0 and gr. (c) time series of ct, cmy and cfy from the nta. (d) time series of tb (19 v), tb (19 h) and tb (37 v). (a) (b) (c) (d) 39voss et al. 2003: polar research 22(1), 35–42 reached after 2 and 3 days for event 1 and event 2, respectively. the maximum values of about – 9 db are well within the range of the σ0 of my. after event 1, σ0 decreases slowly over a period of six weeks to the values before the event (< –12 db), whereas the decrease after event 2 takes only about one week. to elucidate the mechanism of the events, the time series of daily minimum and maximum air temperatures, and the amount of precipitation as measured at the nearby weather station of tasiilaq are also displayed in fig. 2a. several days before the beginning of both events the daily minimum temperature is above (event 1) or around (event 2) 0 °c with amounts of precipitation between 16 mm (event 1) and 4 mm (event 2). the precipitation is caused by low pressure systems connected to warm air advection. the impact of the weather condition on the microwave properties of the surface is discussed in detail in the next section. following the warm air advection, cooler and drier weather is observed for event 1, less so for event 2, and σ0 increases by about 5 db to values above –9 db. as will be described later, freezing of liquid water in the snow layer on top of the sea ice leads to strong volume scattering. the volume scattering is further amplifi ed by the snow metamorphosis due to changing temperatures. following the fi rst event at the beginning of february, σ0 decreases slowly and after about four weeks arrives at its previous values. the slow and steady decrease in σ0 can be explained by the east greenland current, which advects sea ice southward along the greenland coast. with a typical drift of 10 cm/s (martin & augstein 2000), the ice in the event region will be exchanged completely by ice coming from the north over a period of about four weeks. this ice was most likely not subjected to a melting–refreezing process because of the high meridional temperature gradient associated with the polar front typically located in this region. the effect of precipitation strongly depends on the surface temperature, as shown in fig. 2a: while both events are preceded or accompanied by a large amount of wet precipitation (precipitation on days with temperatures above freezing), there is no large increase in σ0 from dry precipitations (i.e. during periods with temperatures below zero). the fast drop in σ0 one week after event 2 is due to a new infl ow of warm air and rain. later on, at the end of april and the beginning of may, σ0 fl uctuates increasingly because of the temperature tending to fl uctuate around 0 °c causes melt–refreezing cycles, and we observe wet precipitation. the time series of pr and gr as well as that of σ0 are presented in fig. 2b. a slight increase of pr and a strong decrease of gr are observed for both events. over the depicted time series, gr and σ0 are anticorrelated with a correlation of –0.63. while no signifi cant variation in the total ice concentration ct (fig. 2c) is observed (pr does not change signifi cantly), the changes of gr cause opposite variations in cmy and cfy. cmy increases from 0 % to 40 % and cfy decreases from 65 % to 25 %. the algorithm to determine the ratio between my and fy is clearly unreliable in this case. a close look at the time series of tb (fig. 2d) explains this artefact. before 3 february the tb (37 v) is higher than the tb (19 v) (gr > 0), but after 3 february the opposite is true. in other words, since the physical surface temperatures are nearly identical, the ratio of the surface emissivities ε37v / ε19v has changed from > 1 before the event to < 1 after the event. moreover, the simultaneous decrease of tb by approximately 10 k to 20 k in all three channels tends to increase the absolute values of pr and gr. it follows that the relative fraction of cfy and cmy are signifi cantly modifi ed. it takes about one month for cfy and cmy to reach their previous values, and a similar period for σ0. as noted earlier, this recovery is mainly due to ice advection, which is a dominant geophysical characteristic of the investigated area. in a previous study of active and passive microwave signatures within the ice pack, ezraty (1999) used a lagrangian approach (in order to discard advection effects) and showed that typical recovery duration for cmy is about two months. to detect melt–refreezing events we prefer to use σ0 instead of gr for several reasons. (1) σ0 is measured independently of the passive data which are already used to estimate the my concentration. (2) σ0 is a physical quantity that can be measured directly. in contrast, gr is a composed quantity (ratio of difference to sum) with not so obvious statistical properties. especially taking the difference in the nominator increases the noise. (3) as a consequence, the signal to noise ratio of the events is higher for σ0 than for gr. this is addressed in the following example: the values of σ0 and gr are investigated at event 1 and during a 59-day period after event 1 between 12 february and 11 april. during this period both quantities are not infl uenced by any other event (see fig. 2). the difference signal between σ0 on 40 improving sea ice type discrimination day i and day i-4 is calculated, similarly for gr. the standard deviations of both difference signals (0.51 db for σ0 and 0.0052 for gr) can be related to the leap of σ0 and gr during event 1 on 3 february (4.4 db for σ0 and 0.036 for gr). for σ0, the leap during the event is 9 times higher than the standard deviation of the differences, but the corresponding ratio of grs is only 6. 4) the brightness temperatures, especially at 37 ghz, can also be infl uenced by both cloud liquid water and cloud ice, as has been demonstrated by liu & curry (2003). we conclude that σ0 is more suitable to detect events than gr. it should be noted, however, that other authors have used temporal information of passive microwave measurements to detect thaw–freeze events, e.g. the onset of melt over sea ice (smith 1998). figure 3 shows the time series of the daily backscatter coeffi cient σ0 of region 2, and the minimum and maximum temperatures and precipitation at kuujjuarapik in the year 2000. the correlation of increase of backscatter with wet precipitation is confi rmed and permits the identifi cation of the starting dates of three events: 23 february, and 20 and 24 march. after the strong increases associated with the fi rst and last event, σ0 remains high with small variations. we explain this different behaviour with the fact that the ice in the hudson bay is fast and is not drifting slowly out of the event region as in region 1, confi rming our fi nding that the slow decreases of σ0 after the large increases in fig. 2a are caused by ice drift and not by ice evolution. the slight decrease of σ0 around 18 april during the third event is attributed to melting conditions and precipitation around this date, but σ0 remains above –11 db. from fig. 3 we also learn how a second event infl uences a surface already affected by a preceding one: σ0 shows the characteristic pattern of decrease and increase, but σ0 is not increased beyond the typical values of –8 to –11 db. towards the end of april, when the melting season starts, σ0 shows strong and irregular variations. in summary, this analysis has shown that in the test regions, events of sudden and large σ0 increase are linked to a strong decrease of the emissivities. these variations occur after surface melt in conjunction with precipitation followed by surface refreezing. similar studies in other regions of the arctic as well as in the antarctic have shown similar changes in σ0 and in the brightness temperatures (voss 2002). snow metamorphosis we now address the reason for the observed changes in the dielectric properties of the surface. since the discussed events are caused by atmospheric effects, it is likely that the uppermost surface layer, i.e. the snow cover, plays a crucial role. the snow depth on arctic sea ice typically ranges from about 5 to 40 cm (ledley 1991). three phases of snow metamorphosis caused by an event can be identifi ed: initial state, melting phase and refreezing. in the fi rst phase, the snow layer is dry and has low density with small absorption and scattering (ulaby et al. 1986). it is nearly transparent at the wavelength used here (2.2 cm). both active and passive microwave mainly stems from the underlying sea ice surface. when surface melt occurs because of warm fig. 3. time series of daily qscatσ0 data averaged over the test area off kuujjuarapik, hudson bay) during 2000 (thick solid line), the daily maximum temperature (tmax: thin solid line), minimum temperature (tmin: dotted line), and the amount of precipitation (histogram). 41voss et al. 2003: polar research 22(1), 35–42 air advection, the liquid water in the snow will aggregate the small crystals to coarsely grained clusters (massom et al. 2001). this process can be amplifi ed by rain. the liquid water increases the dielectric losses, increases the emissivity and reduces the penetration depth to about one wavelength. volume scattering becomes negligible, and both emissivity brightness temperature increase (smith 1998). during an event of few days, the temperature in the deeper snow layers remains below freezing. it can be speculated that, similar to the observations of haas (2001) in antarctica, percolating melt and rain water refreezes and forms a rough icy layer in the snow or at the snow–ice interface. the sea ice underneath is not or only slightly affected. the third phase starts when temperatures decreases below freezing again so that liquid water creating larger grains and voids in the snow layer (massom et al. 2001). the penetration depth increases again because liquid water is no longer present. the larger grains increase volume scattering resulting in lower emissivity and brightness temperatures. results geographical distribution of events the spatial distribution of the events detected is shown in fig. 1. medium and dark grey both represent regions of fy. dark grey indicates areas where at least one event is detected from october to may during the two winter periods under consideration. within the seasonal sea ice zone, where fy grows, events occurred in the following regions: the southern and mid-hudson bay; the coast of labrador in the labrador sea; denmark strait; the kara sea, especially between novaya zemlya and the siberian coast and in several bays of the laptev sea; in the sea of okhotsk along the russian coast, the sakalin island and in most parts of the bering sea. it is not surprising that events occur in these marginal seas since this is where cyclones advect warm air and rain. large-scale estimation of event area to estimate the error induced by the described meteorological infl uences on the fy classifi cation, the area of spurious my detected by the nta during winter has been estimated when no new my is formed. to this end we exclude all regions where my (1) can have survived the last summer or (2) can be advected by ice drift (both marked in light grey in fig. 1). for the remaining fy area, the my output of the nta increase from 0 to 0.3 × 106 km2 in the entire arctic region from october 1999 to may 2000 and from october 2000 to may 2001, respectively, due to falsely detected my. note that this my area correction corresponds to a much larger total area affected because the error in my concentration during an event is between 10 and 20 %, with initial values up to 40 % (fig. 2c). the fy area correction accounts for about 13 % of the total area where an event is detected (2.3 × 103 km2) according to the two criteria that σ0 (1) increases by more than 3 db within 4 days and (2) reaches values of –11 db or higher. the total ice-covered area of the whole arctic ocean reaches about 12 × 106 km2 in mid-winter. the my area estimated by the nta is approximately 2.5 × 106 km2, most of it being the real my of the central arctic. but as shown here about 12 % of the total arctic my calculated with the nta is an artefact and should be replaced by fy. assuming a static mask for the my area is conservative because areas containing mixtures of fy and my are also excluded from the correction scheme. therefore, future applications, e.g. aiming at improved time series of my concentrations and extent, should include a more sophisticated, dynamic discrimination between fy and my. this will lead to even larger corrections. the correction of the passive microwave data for the period when ku-band scatterometer data are available appears straight forward, and the correction of the complete 20-year data set of passive microwave imagery, which would have to be based on the data themselves, especially the gr (fig. 2), could be optimized with data of the overlap period of both sensors. conclusions as sea ice ages, its microwave radiative and backscatter properties are modifi ed. in particular, multi-year sea ice (my) has a lower emissivity than fi rst-year sea ice (fy) because desalination reduces dielectric loss. the lowering of emissivity depends on the frequency and is exploited by the 42 improving sea ice type discrimination nta to discriminate fy from my. furthermore, my backscatter (> –11 db) is larger than that of fy (< –11 db) because of both increased surface roughness at microwave wavelength scale and increased volume scattering due to air pockets. in this study, using routine meteorological information, it is shown how and why melt–refreezing events, enhanced by rain, alter the normal microwave signature of sea ice. the nta will underestimate the amount of fy and overestimate the amount of my while the total sea ice concentration remains unchanged. an alternative possibility of a rapid backscatter increase of fy not discussed in this study is ice compression with an associated increase in roughness and ridging. the addition of backscatter data allows correcting for this effect and the nta can be corrected accordingly. as an example, such a simultaneous use of ssm/i and qscat data has been performed in the arctic seasonal sea ice zone, where most of these events were detected during two consecutive winter periods. the correction amounts to up to 12 % of the area. acknowledgements.—ssm/i data were provided by the national snow and ice data center, university of colorado, boulder and the seawinds/qscat maps by ifremer/ cersat, brest. the weather data were provided by wetteronline gmbh, bonn. the fi rst author acknowledges a grant from eumetsat for supporting his stay at institut français de recherche pour l’exploitation de la mer, brest. references bingham, a. w. & drinkwater, m. 2000: recent changes in the microwave scattering properties of the antarctic ice sheet. ieee trans. geosci. rem. sens. 38, 1810–1820. cavalieri, d., crawford, j., drinkwater, m., eppler, d., farmer, l. jentz, r. & wackerman, c. 1991: aircraft active and passive microwave validation of sea ice concentration from the defense meteorological satellite program special sensor microwave imager. j. geophys. res. 96(c12), 21 989–22 008. ezraty, r. 1999: arctic sea ice microwave signatures. a lagrangian approach during the nscat mission. in: igarss ‘99 hamburg germany: ieee 1999 international geoscience and remote sensing symposium, 28 june–2 july 1999—congress centrum hamburg; remote sensing of the system earth—a challenge for the 21st century; proceedings. pp. 1585–1587. ezraty, r. & cavanié, a. 1999: intercomparison of backscatter maps over arctic sea ice from nscat and ers scatterometer, j. geophys. res. 104(c5), 11471–11483. ezraty, r. & piollé, j. f. 2001: seawinds on quickscat polar sea ice grids—user manual. convection report 5, v1.1, august 2001. brest: institut français de recherche pour l’exploitation de la mer. available on the internet at www.ifremer.fr/cersat/ activite/ceo/imsi/f4i_html/e_ intro.htm. gloersen, p., campbell, w., cavalieri, d., comiso, j., parkinson, c. & zwally, h. j. 1992: arctic and antarctic sea ice, 1978–1987: satellite passive-microwave observations and analysis. washington, d.c.: national aeronautics and space administration. gohin, f. & cavanié, a. 1994: a fi rst try at identifi cation of sea ice using the three beam scatterometer of ers-1. int. j. remote sens. 15, 1221–1228. haas, c. 2001: the seasonal cycle of ers scatterometer signatures over perennial antarctic sea ice in summer. ann. glaciol. 33, 69–73. hollinger, j. p., peirce, j. l. & poe, g. a. 1990: ssm/i instrument evaluation. ieee trans. geosci. remote sens. 5, 781– 790. johannessen, o., shalina, e. v. & miles, m. w. 1999: satellite evidence for an arctic sea ice cover in transformation. science 286, 1937–1939. kwok, r., comiso, j. c. & cunningham, g. f. 1996: seasonal characteristics of the perennial sea ice cover of the beaufort sea. j. geophys. res. 101(c12), 28 417–28 439. kwok, r., cunningham, g. f. & yueh, s. 1999: area balance of the arctic ocean perennial ice zone: october 1996 to april 1997. j. geophys. res. 104(c11), 25 747–25 759. ledley, t. s. 1991: snow on sea ice: competing effects in shaping climate. j. geophys. res. 96(d6), 17 195–17 208. liu, g. & curry, j. 2003: observation and interpretation of microwave cloud signatures over the arctic ocean in winter. j. appl. meteorol. 42, 51–64. martin, t. & augstein, e. 2000: large-scale drift of arctic sea ice retrieved from passive microwave satellite data. j. geophys. res. 105(c4), 8775–8788. massom, r., eicken, h., haas, c., jeffries, m. o., drinkwater, m., sturm, m., worby, a., wu, x., lythe, v., ushio, s., morris, k., reid, p., warren, s. & allison, i. 2001: snow on antarctic sea ice. rev. geophys. 39, 413–445. parkinson, c. l., cavalieri, d. j., gloersen, p., zwally, h. j. & comiso, j. c. 1999: spatial distribution of trends and seasonality in the hemispheric sea ice covers: 1978–1996. j. geophys. res. 104(c9), 20 827–20 835. serreze, m., walsh, j., chapin, f., osterkamp, t., dyurgerov, m., romanovsky, v., oechel, w., morrison, j., zhang, t. & barry, r. g. 2000: observational evidence of recent changes on the northern high-latitude environment. clim. change 46, 159–207. smith, d. m. 1998: observation of perennial arctic sea ice melt and freeze-up using passive microwave data. j. geophys. res. 103(c12), 27 753–27 769. ulaby, f. t., moore, r. & fung, a. k. 1986: microwave remote sensing, active and passive. vol. iii. norwood, ma: artech house. wetteronline gmbh 2001: on the internet at www.wetter online.de, 15 december 2001. voss, s. 2002: synergetische charakterisierung von meereis mit ssm/iund scatterometerdaten. (synergetic characterization of sea ice with ssm/iand scatterometer data.) phd thesis, institute of environmental physics, univer sity of bremen. heavy metals and sulphur in mosses from southern spitsbergen krystyna grodzinska and barbara godzik grodzinska, k. & godzik, b. 1991: heavy metals and sulphur in mosses from southern spitshergcn. polur research y(2i3 133140. concentrations of cd, pb. ni. cu. zn and s were determined in 16 nioss species collectcd from 9 localities in southern spitsbcrgcn (mostly within the hornsund region). two species, sanionia uncinrrfa and hybcumiuni splendens, were objects of more thorough studies. i n sanionia uncinara the mean con centrations werc ( ~ d g ) : cd-0.59, pb-7.07, ni-4.25. cu-6.01. zn-21.13 and s1.481. hylocomium splendens accumulated similar quantities of these elements. the concentrations of metals and sulphur in mosses differed significantly ( p < 0.05) from site to site. depending on geological and climatic conditions specific to the arctic region. the effect of remote sources of pollution reaching spitshergen on the levels of heavy metal concentrations was taken into account, a5 well as thc effect of local emissions from the polish polar station. at 1@25 metre distances from the station. thc levels of heavy metals and sulphur werc 3-10 times higher than at a 300-metre distance. krysryna grodzrnska and barbaru godzik. w. szafer insfirrite of b o t a ~ i , ~ . polish aradertly of sciences. luhicz 46, 31.312 kruk6w. poland. introduction the arctic environment is influenced by chemical elements of both anthropogenic and natural origin and from remote as well as local sources (jaworowski 1989). the svalbard region is exposed to a greater atmospheric transport of inpurities from distant sources than some other arctic areas (rahn et al. 1983; penkett 1984; pacyna & ottar 1985; ottar et al. 1986; heintz enberg 1989; jaworowski 1989). the island seems to be affected by airborne pollutants originating in western europe and the soviet union and to a lesser extent in north america (rahn & show 1982; rahn 1984; maenhaut et al. 1989). local sources of pollution, e.g. mines, miners' colonies and polar stations (krzyszowska 1985a), are thought t o contribute only negligible quantities of pollutants compared with remote sources (lan nefors et al. 1983). the extent of environmental pollution is often assessed by employing plants of various sys tematic groups as bioindicators (grodzinski & yorks 1981). mosses have commonly been used as bioindicators of pollution by heavy metals (riihling &tyler 1973,1984; ruhling et al. 1987; grodzinska 1978; grodzinska et al. 1990) and, to a lesser extent, as indicators for sulphur com pounds (winner & atkinson 1987; szarek & chrzanowska in press). the aim of our study was to assess the degree of environmental pollution in a large area of southern spitsbergen as well as the area closely surrounding the polish polar station in the hornsund area; as bioindicators, we employed various species of moss. material and methods sixteen species of mosses were collected in arctic tundra ecosystems at 1-9 sites within an area of 30,000 km? in southern spitsbergen. eight species were collected at 1-6 sites within 10 to 300-metre distances west and east of the polish polar station (figs. 1 and 2). all the samples were taken at the beginning of june 1985, immediately after snow melting. the unwashed mosses were separated into green and brown shoots and stored in paper bags. the material was dried to a con stant weight at 85". the samples were then wet digested in a 4:l mixture of concentrated spectral pure nitric (hn03) and perchloric (hc104) acids on a hot plate for 3 days until all organic matter was oxidized. the solution was evaporated to 1 ml and then diluted with distilled water to 50 ml. pyrex glassware was used for the chemical procedure. 134 krystynn grodziriska & burbara godzik i i i 1 l' 16' 18' 1 22' 2 6 0 25 50km u heavy metal ( c d , pb. ni, cu. z n ) conwere(yg/g): cd-00.01. cu-0.01, f e 0 . 3 , m n 0.0. ni 0.02, pb 0.04. z n 0 . 1 c a 0.6. m g 0.2 and s 5 . nonparametric two-way variance analysis and h-test (sokal& rohlf 1969) were used to estimate the differences between element concentrations in moss species from the various sites. centrations were determined in the water solution by atomic absorption spectrophotornetry (varian techtron a-1000). total sulphur was determined by the butters-chenery method according to nowosielski (1968). blanks were run in each series of samples. t h e concentrations of metals and sulphur in the blanks heavy metals and sulphur in mosses from southern spitsbergen 135 i i i i 77’ j i i i i i i 3. ariekammen 4. fugleberget 5 .gnalodden 6.treskelen 7. gash a m n a 8,palffyodde n pps polish polar station 15’ 15’20’ 15’40’ fig. 2 . sites of moss sampling in the hornsund area. results heavy metal concentrations in mosses from southern spitsbergen considerable differences among concentra tions were found for particular species (table 1). the moss species can be divided into two groups as far as the accumulation of some chemical elements is concerned. aulacomium palustre and a . turgidum, hylocomium splendens, sanionia uncinata and tortula ruralis are good accumu lators for heavy metals while racomitrium lanu ginosum, polytrichum alpinum and dicranum groenlandicum are not. the members of the first group show significant ( p < 0.05) differences in heavy metal concentrations at different sites within southern spitsbergen, whereas moss species of the second group show more homo geneous results (table 2). two species (hylocomium splendens and sanionia uncinata), which accumulate rather large quantities of heavy metals were chosen for assess ment of the extent of environmental pollution. 16‘ 16’20’ sanionia is a very common species throughout the area. hylocomium is much less common, but it was chosen because of its widespread use as a bioindicator of environmental pollution else where. the mean concentrations of heavy metals in sanionia uncinata in southern spitsbergen were as follows (pg/g): cd-0.59, pb-7.07, ni-4.25, cu-6.01 and zn-21.13 (table 3). hylocomium splendens accumulates heavy metals at similar concentrations: cd 0.66, pb 6.54, ni 3.56, cu 6.08 and zn 23.80 (table 4). the concentrations of heavy metals in both sanionia uncinata and hylocomium splendens varied among the sites (tables 3, 4; fig. 3). the highest quantities of cadmium in sanionia unci nata were accumulated at the gnilodden site, of nickel and copper at the treskelen site, of zinc at a southernmost sorkapp site, and of lead at the palffyodden site (table 3; fig. 3). the least quan tities of cadmium, zinc and copper were found at the gishamna site, of lead and nickel at the werenhus site (table 3; fig. 3). when the sites are arranged in order of increas 136 krvstyna grodziriska & barbara godzik tobit. i concentration\ (.>i tie,n,! metal, and total \ulphur icig g ' d , w t ) in rno\\ch from southern spitsbcrgen (valucs arc ineanh oi . ? ? i \:imples). ~ cd ph n i cu z n s spcllc\ n x s d \ s d u s d x sd x s d y sd aulacomnium palustrc (hcd* ) schwacgr. aulacomnium turgidum ( w h l b . ) sch\\acgr. brachkthccium turgidum ( h a r t m . ) b.s.g callicrgcln \tramincum ( b r i d . 1 kindh. dicranum grocnlandicum brid. dicranum spadiceum zett. ditrichum rcuicactle (schlcich.) h a m p r hyloconiium \plendcns ( l 3 e d w . i b . s cj plcurozium schrcberi mitt. polytrichum alpinum hedw. polytrichum commune hcdu . racomitrium ericoidc\ (urid. 1 brid racomitrium lanuginosum (hcdu.1 brid. sanionia uncinata h e d w . tomcntvpnuni niten\ ( t f e d w . ) locskc tortula ruralis ( f l c d u , . ) g a e r t n . . meyer e t schsrb. 6 11.83 ( i . l x 6.69 1 . 4 2 8.31 5 4 1 13.98 i5 0.77 u.19 5.68 3 i ? 2.57 0.81) 3.31 3 1.95 i1 37 3.50 i1 74 1.81 0.45 4 . 4 2 3 0.82 oo6 4.03 11.77 7.29 0.45 6.11 8 0.46 1.12 2.93 1.36 1 7 0 0.59 3.67 8 0.59 0.21 5.70 2.16 2.41 045 3.02 3 11.44 0.13 1.60 (1.04 0.79 0.02 2.15 9 0.66 i1 i 2 6.54 1.45 3.56 1.25 6.08 6 0.63 u.14 6.mi 3 . 5 1 3 y(l 1.65 2.92 8 0 . 4 2 ko9 3 5 8 1.87 2.33 0.71 4.34 3 i).% 0.04 lj.94 11.78 1.71 0.21 4.76 3 0.82 lj.07 7.115 1.30 12.56 0.56 17.69 i 8 0.31 (1.09 4.86 2.20 2 . 3 5 0.87 2.31 21 0.59 0.13 7.07 4.49 4.75 2.53 6.01 6 0.71 (1.11 6.44 l 4 y 8 75 6.92 5.92 12 0 . x 5 ij.4il 5 22 1.76 3.57 0.84 6.90 13.07 ?y.(iz 5.33 1.97 26.76 6.96 0 . i x 20.33 0.48 u.no 29.07 1.27 0.76 16.39 4.43 1.03 17.19 5.22 0.00 9.811 0.86 3.01 23.80 9.88 1.05 19.35 6.01 0.40 18.69 3.19 0.5x 24.01 0.32 1.80 42.87 2.31 1.91 13.04 4.94 4.52 21.13 4.98 7.07 26.70 17.65 3.30 31.74 14.21 903 220 1081 247 1168 314 1219 325 1190 282 1112 322 780 52 1103 297 1224 368 1238 303 1294 313 1586 37 561 164 1481 143 1256 41 1718 369 ing concentrations of heavy metals. the list starts with the gilshamna and werenhus sites and ends with the treskelen. gnalodden and palffyodden sites (table 3 ) . total sulplzitr concentration in mos.res from southerti spirshergen the concentrations of sulphur are highest in saniotiia uncinatu, aulacomium turgidurn and hyloconiium splendens and many times less in ritcomitrium lanuginosum and polytrichum alp inum (tables 1 , 3 and 4). t h e r e are statistically significant (p < 0.05) differences in sulphur con centrations in mosses between sites (table 2). sanionia. f o r example, accumulated the least sul phur on the werenhus site, the most on the arie karnrnen site (table 3). i d d r 2 s t a t i m u i anal!si\ of the differences betuc.cn hc.a\! iiic.tak. and total w l p h u r conccntrations in moss species from various sit^ in w u t h c r n s p i t s h c r y n . " specie, aulaconiniurn turgidurn dicranuni grr~enlandicuiii ti! locnmiuni splcndens polttrichum alpinum racomitriuin lanuginosum snnionia u n c i n d i i t o r t ui;i r 11 ralk cd u.uu.1* i1 6")"' 0.u4 i ' 11.362"' 0.457"' o.ij21 ' o.(wji cu ~ zn s 0.00(1* 0.044* o.u44* 0.223"' 0.103"' 0.007 * o . l ~ o o * o.og€* 0. om* 0.1)11* o.oo7 * (1 181"' 0.001' 0.982"' 0.022* 0.044" 0. (106 * 11.008' 0.000* 0.000' 0.011* . p '. i l 115 " sc\cn m o b \ \pecic\ occurring in more than n o sites here used for statistical analysis (cf. table i ) . heavy metals and sulphur in mosses from southern spitsbergen 137 table 2 . concentration5 of hcavy mctals and total sulphur (pgg i d . w t ) in suiiionicc uncbiatci collected from 8 sites in aouthrrn spitahergen. values are means of 3 samplcs cach. site cd ph ni cu zn s u sd x sd x sd x sd x sd x sd wcrcnhua rotiesfjellet fuglehergov arichammcn gnalodden trcskclcn gaahamna palffyoddcn smkapp average ~~ 0.526 0.07 3.36 0.34 1.60 0.04 2.85 0.61 20.95 9.91 1330 i l l 0.679 0 . 0 8 4.99 1.08 2.37 0.(16 2.73 0.58 17.16 1.51 0.723 (1.817 0.582 0.406 0 502 0.576 0 598 0.12 9.48 1.55 5.06 (1.39 9.51 li.(lo 21.98 1.31 i626 64 0.05 12.0 2.11 3.30 0.27 4.27 0.00 26.17 u.31 ~ 0.05 5.12 0.54 x.xx 0.24 14.96 1.54 2.5.00 1.92 1600 52 0.04 3.8s 0.55 2.07 (1.22 2.(j5 0.00 12.3x 1.14 1370 0 0 . o x 16.26 0.52 6.76 0.11 6.84 0.84 22.83 0.35 0.115 4.6o 0.3y 4.67 0.55 5.60 11.70 27.00 1.56 0.13 7.07 4.49 4.35 2 . 5 3 6.01 4.52 21.13 4.98 14x1 i43 concentrutions of lzeavy metals mid sulphur in the surroundings of the polish polar station within 10 to 25 metre distances from the polish polar station the concentrations were several times higher than those at the ariekammen site which is about i km distance from the station; the concentrations were also higher than the mean concentrations in sanionia uncinatu on 8 sites of southern spitsbergen (table 5). most remarkable were the differences in concentrations of zinc ( l o x ) , copper ( 6 ~ ) and lead ( 3 ~ ) between sites within 10-25m of the station and the arie kammen site. the differences were less pro nounced in the cases of nickel and cadmium (table 5 ) . around the station sanionia iincinata had higher amounts of heavy metals than h y l oconiium splendens (table 5 ) . at 150-300 metre distances from the station, the heavy metal concentrations did not differ from those at the ariekammen site and the 8 sites of southern spitsbergen (tables 3-5). the total sulphur concentrations in mosses col lected in the entire 10 to 300 metre zone near the station were uniform and did not differ from those found at the ariekammen site (tables 3- 5). discussion the different concentrations of heavy metals in mosses noted from the various sites in southern spitsbergen situated several kilometres to several tens of kilometres suggest local causes of such differences. spitsbergen is an area with very diversified geology. the southern part of spitsbergen con sists mainly of precambrian formations of hoeckla hoek, accompanied by rocks of carbon. permian and devonian age (smulikowski 1965). in the fjord hornsund there are quartz, ankerite. and ankerite-quartz ore-bearing veins. these veins often contain pyrite and chalcopyrite; less often they contain pirotyne, galena, sphalerite. limonite, cuprite, malachite and azurite (bir kenmajer & wojciechowski 1964; wojciechowski table 4 . concentrations of hcavy metals and total sulphur (lip g ' d . w t ) in hyloconiiim splendcns collected from 3 sites in southern spitsbcrgen. values arc means of 3 samplcs cach. ~~ cd pb ni c u zn s site x s d x sd x s d u sd x sd x s d rotjesfjellet 0.75 0.12 6.4 0.62 3.63 0.45 1.08 0.00 17.77 3.09 730 13 ariekammen 0.518 0.03 5.05 0.43 2.37 0.06 4.0x 0.00 36.2 2.x6 140(1 34 fuglcbcrget 0.719 0.08 8.18 0.72 4.69 1.43 10.10 0.00 17.45 1.00 1180 40 ~~ ~ average 0.662 0.13 6.54 1.45 3.56 1.25 6.ljx 3.47 23.x0 y.88 il(13 297 138 krystyna grodziriska & barbara g o d z i k pb ppm‘ ni,cu.pb cu :d cd l z r zn i0 20 nt 10 !3$5 6 7 8 9 fig. 3 . concentration of cd, ni, cu. pb and zn (ppm d . w t . ) in sonionio uncinara collected from different sites in southern spirshergen: see fig 2 for locations of sites 1-8; site 9 = ssrkapp 1964). the rocks of fugleberget, ariekammen, gdshamna and palfyodden, where most of zn, cd and pb. samples of mosses were collected, are rich in pyrite and chalcopyrite (wojciechowski 1964). these rocks contain higher concentrations of heavy metals, mainly fe and cu, sometimes also rather high concentrations of heavy metals (except pb) in svalbard soils are reported by steinnes (1984) and thomas (1986). table 5 . cmccntrations of hcavy mclal\ and total sulphur (118 g ’ d . w t ) in s o t t r o f ~ i o ioicitiorci ( s ) and hvlocornium splrriclen~ ( h ) coilcctrd in variow distances from thc polish polar station vaiucs arc mcans of 3 samplcs cach. cd ph ni c u zn s s1tc t sd x s d x sd x s d i sd x s d s 1.15 0.14 30.18 0.00 6.04 0.45 36.90 2.30 226.0 50.90 1450 0 0.h7 0.09 15.56 0 38 5.55 0.77 14.24 0.64 96.9 1.21 1146 35 i1 68 1).04 11.75 2.10 3.85 0.32 8.66 1.22 47.3 1.10 1136 11 5 i) 44 (1.12 8.98 1 . 1 1 4.53 i1.m) 7.44 0.m) 4 6 . 2 6.36 i663 35 s 0.41 (1.06 6.w 0.89 3.15 0 . 6 4 4.yx 0.00 2 1 . 3 0.77 i 1 s i i y 5 0.06 2 1 . 1 1 2.03 4 5 3 ij.ih1 ?&(i4 2.30 76.y 0.x7 1360 69 11 s i1 5 7 0.07 5.54 0.47 3 . 1 4 0.86 7.77 0.47 145.9 5.16 i o o m e ,, 1 0 m w i , 7 0 m w 150 inm’ s i1 56 11.05 x.93 0.79 3.93 0.57 x.66 1.22 73.9 8.98 i i i1 35 1 ~ . 1 i o 8.19 0.00 2.x8 11.49 y.90 1.56 45.7 4.11 ~ 3oo 111 m’ ~ ~ ~ 25 m e ~ heavy metals and sulphur in mosses f r o m southern spitsbergen 139 in the arctic areas, superficial rocks are weath ered into fine particles due to the erosive action of air and water. in southern spitsbergen, the snow cover persists for 9-10 months. during the short 2-3-month summer, abundant waters from melting snow flow over the surface of rocks and moss mats. they carry a variety of rock fragments, minerals, and chemical compounds which can easily be absorbed by plants (krzyszowska 1985b). mosses have no epidermis and cuticula, therefore their cell walls are easily penetrable for metal ions (tyler 1971, 1972). it may be supposed that there is a relationship between the levels of at least some of the heavy metals in mosses and the substrate in the southern part of spitsbergen. the chemical analyses within this project covered only mosses; the chemical composition of soil and rocks was not determined. no data are therefore given here which could document correlations between the concentrations of heavy metals in mosses and substrate in individual sites in sou thern spitsbergen. many published studies (rahn et al. 1983; heintzenberg 1989; jaworowski 1989) state that air pollutants from industrialized parts of the northern hemisphere reach the arctic regions by way of long distance transboundary transport. these pollutants enter arctic tundra via precipi tation. mosses, the main components of this tundra, have no organs for uptake of minerals from substrate; they obtain minerals, as well as pollutants, from the atmosphere from precipi tation and dry deposition (tyler 1971). hence it may be expected that high concentrations of heavy metals and sulphur in the mosses of sou thern spitsbergen are, at least, in part, caused by the long range transboundary transport of pol lutants in gaseous and particulate form. our data for heavy metal concentrations in mosses from southern spitsbergen have been compared with similar data from sweden, iceland, and greenland (riihling et al. 1987). the levels of lead and zinc in spitsbergen mosses are several times lower than those found in sweden, but similar to those from iceland and greenland. however, the copper concentration in mosses from spitsbergen was similar to that in sweden and 2-3 times less than copper con centrations in mosses from iceland and green land. the mosses from southern spitsbergen contained considerable quantities of cadmium and nickel, higher than found in mosses from scandinavia, iceland and greenland. our results are in a good agreement with the heavy metal concentrations in plant mat erial collected in spitsbergen and reported by jaworowski (1967), thomas (1986), and ottar et al. (1986). ruhling et al. (1987) demonstrated decreasing heavy metal concentrations from south to north in scandinavia as an effect of the transboundary transport of pollutants from western europe. lead, zinc and copper follow this pattern in south ern spitsbergen; cadmium, nickel and sulphur do not. staaland et al. (1983) found much higher con centrations of metals in reindeer forage plants (lichen, bryophytes, forbs) from svalbard than in plants from continental norway. jaworowski (1989) suggests that this might be due to the greater availability of metals in svalbard soils, a result of intensive weathering processes. the level of heavy metals found in mosses collected within a 10-300 metre radius around the polish polar station at hornsund proved that the chemical effects from the station are local and present no threat to the arctic tundra ecosystems. similar conclusions have been reached by krzyszowska (1985a). according to her assess ment, the anthropogenic impact of the station is rather insignificant, affecting no more than 3.5 hectares. because of specific climatic conditions and the diversified chemistry of the substrate in the arctic regions, the mosses should be applied as indi cators of air pollution by heavy metals only with caution. mosses in the close surroundings of local sources of pollution, for example polar stations, in uniform geological conditions can prove to be very sensitive indicators of local changes in the atmosphere. sanionia uncinata, hylocomium splendens and other species representing the first group of mosses distinguished in this study can be regarded as good indicators of pollution originating from local sources. the other group (among others racomitrium canescens and polytrichum alpinum) shows less diversity in heavy metal con centrations between sites in southern spitsbergen, being less affected by substrate composition. this group may be used for monitoring pollutants orig inating from distant, transboundary sources. acknowledgements. this work was supported by the polish academy of sciences, programme cpbp 03.03. 140 krystyna grodzinska & barbara godzik references birkenmaler k . & wojciechowski. j . 1964. on the age of ore bearing veins of the hornsund area. vestspitshergen. studia geol. pol. 11. 179-184. grodzinska. k . 1978: mosses as bioindicators of heavy metal polluti(in in polish kational parks. w a f e r . air und sod pol lution 9. 83-97, grodzinska. k.. srarck. g . & godzik. b. 190: heavy metal deposition in polish national parks ~ changes during ten yean. wuwr. air and soil pollution 49. 41%4ly. grodzinski. w. & yorks. t. p. 1981: species and ccosystcm level hioindicators of airborne pollution: an analysis of two major studies. water. a i r and soil pollurion 16. 32-53. ileintzenherg. j . 1989: arctic haze: air pollution in polar regions ambro 18. 50-55. jaworowski. z. 1967: stable and radioactive lead in environ ment and human body. nuclear energy lrformatiorr center. warsau,. report no. neic-rr--79. 1-181 jaworow\ki. z. 19x9: pollution of the norwegian arctic: a review. a'ortk polarrnsritutr rapportserie 5.5. y3 pp. krz!sznwska. a. j 19x5a. tundra degradation in thc vicinity ot the polish polar station. hornsund. svalbard. p o h r rtworch 3. 247-251. krz>szoa'ska. a. j 1yx5h: chemist9 of the freshwdter of the fuglcherget drainage b a h pol. polar kes. 6. 341-347. lanncfor-,. h.. heintzenherg. j . & hansson. h.ch. 1983: a comprehensive study of physical and chemical paramctcrs of the arctic w m m e r aerosol: results from the swedish expedition ymer-xi). tellics 3-7 b . 4(!-54. maenhaut, w . , cnrnille. p . . pacyna. j . m 8: vitols. v. 1989: trace element composition and origin of atmospheric aero w l r i n thc norwegian arctic. atrnos. enorron -73f111. 1551 1578. n o u o w a s k i . 0 . i 9 h r : m e r o i l ! o z r i a c x i i i u purrzeh nuwofenru. lvaruawa pwril hhx p p . ottar. b y . , gotta5. y . hob. 0 . . ibersen. t . , jorangcr. e . . ochmc, m.. pacyna. j . scmh. a , . thomas. w . & vitols. v 19xh: air pollutant\ i n the arctic. , v l l l or: 30'86. 1 x l l . pacyna. j . m. & ottar. b . 1985: transport and chemical com position of the wmmer a e r o d i n the sorwegian arctic. a tmot . en oiron, l y. 7 109-2 120. penkdt. s. a . 19x4: implications of arctic air pollution. .ibrure 31 i . 2!)9 kahn. k a 1984: who', polluting the arctic? .varurul hisrurr. 9 1 . 1-4. rahn, k . a . & show, e . g . 1982: sources and transport of arctic pollution aerosols: a chronicle of six years of onr research. navul research r e v . 1982 34, 2-26. rahn. k. a , . lewis, n. f . , lowenthal. d. h . & smith, d. l. 1983: noril'sk only a minor contributor to arctic haze. narure. 306. 45%461. ruhling. a , . rasmusscn, l . . pilegadrd, k . , mikinen, a . & steinnes. e . 1987: survey of atmospheric heavy metal depo sition in the nordic countries in 1985. n o r d 21, 1-44. riihling. a . 61 tyler, g . 1973: heavy metal deposition in scandinavia. water. a i r and soil pollution -7, 445-455. ruhling. a . &tyler, g . 1984: recent changes in the deposition of heavy metals in northern europe. wuter. a i r and soil pollrtriori 2 2 , 17s180. smulikowski w. 1y65. petrology and some structural data of lover metamorphic formations of the hoeckla hoek suc cession in horsnund. vestspitsbergen. studia geol. pol. 18. 1-107 sokal. r. r . & rohlf. f. j. 1969: biometry. freeman and company. san francisco. 776 pp. staaland. h . , brattbakk. i . , ekern, k. & kildemo, k. 19x3: chemical composition of reindeer forage plants in svalbard and norwaay. holarrric ecology 6, 10%122. steinncs. e. 1984: lleavy metal pollution of natural surface soil due to long-distance atmospheric transport. pp. 115-122 in yaron. b., dagan. g . . goldshmid, j . (eds.): pollutarrtv in porous m e d i u . springer verlag. berlin. szarek. g . & chrzanowska. e . in press: sulphur content i n the mosses of polish national parks-hanges during ten years. actu soc. bor. pol. thomas. w . 1986: accumulation of airborne trace pollutants i n arctic plants and soil. wut. sci. tech. 18, 47-57. tyler g . ly7l: moss analysis: a method for surveying heavy metal deposition. pp. 12s132 in englund. h . m . & berry, w . t . ( e d s . ) : proceedings o f t h e 2nd international clean air cotrgress. washington dc. tylcr g . 1972: heavy metals pollute nature. may reduce pro ductivity. a m b i o / . 57-59. winner. w . e. & atkinson. c. 1y87: annual absorption of gaseous air pollutants by mosses and vascular plants in diverse habitats. pp. 427-43x in hutchinson. t . c. & meema. k . m . (eds.): effects of atmospheric pollutants o n forests, wetlands and agricultural ecosystems. n a t o a s / serie.s rml. 6, 16. springer verl. london-paris-tokyo. wojciechowski j . 1964: ore-bearing veins of the hornsund area. vestspitshergen. studia geol. pol. / i . 173-177. phytoplankton growth and light absorption as regulated by light, temperature, and nutrients dale a. kiefer and john j . cullen * kiefer, d. a . & cullen, j . j . 1991: phytoplankton growth and light absorption as regulated by light, temperature. and nutrients. pp. 16x172 in sakshaug. e.. hopkins. c. c. e. & britsland, n . a . (eds.): proceedings of the pro mare symposium on polar marine ecology. trondheim, 12-16 may 1990. polar research l o ( 1 ) . numerous studies of the growth of phytoplankton in the laboratory have demonstrated the dependence of cellular pigment concentration and growth rate upon light intensity, photoperiod, temperature, and nutrient supply. these same environmental parameters vary with season in the polar seas and presumably affect the growth rate and cellular pigment concentration of the phytoplankton crop. unfortunately, there has not been a complete mathematical description of the interaction of all four environmental parameters. this study presents an approach to describing these interactions. it can reasonably be assumed that the gross specific growth rate. g. is a function of the specific rate of light absorption: g = n r (l-exp(-a, $,,, e d n 6 ) ) . the dependent variables in this equation are g, the gross specific growth rate, n , the maximum carbon specific photosynthetic rate, and, 6 . the ratio of carbon to chlorophyll. the value of all three dependent variables is constrained. the independent variables are e,). the light intensity (assumed constant during the photoperiod), and r. the photoperiod (as a fraction of 24 hours) that the cells are illuminated. n is the instantaneous capacity of the dark reactions to assimilate electrons, while the product a p $mrr e,jb is the instantaneous capacity of the light reactions to supply electrons. if the capacity for photochemistry exceeds the capacity for assimilation. dissipative processes occur, and the quantum yield is low. we have applied this equation to the analysis of the growth and light absorption by skelefonema costafum cultured under light. temperature, and nutrient limitation. decreases in nutrient supply and tcmpcrature cause decreases in n and increases in 6; thus both the capacity for electron supply and utilisation decrease. however. decreases in temperature decrease the capacity for electron assimilation more rapidly than the capacity for supply; quantum yield drops. decreases in nutrient supply cause the capacity for supply and assimilation to drop in parallel; quantum yeield is maintained. decreases in day length cause dccrcases in 0 and increases in n. the capacity to assimilate electrons and the capacity to supply electrons increase in parallel; quantum yield is maintained. decreases in light intensity cause decreases in both band the capacity to supply electrons. although the changes in n with light intensity are difficult to assess. the capacity to assimilate electrons appears to be little changed by light limitation. quantum yields increase with decreasing light levels. dale a. kiefer. department of biological sciences, university of southern california, university park, los angeles. california wo89-0371, usa; john j . cullen. bigelow laboralory for ocean science, mckown point. west boothbay harbor, maine 04575, usa. introduction a number of factors may limit the growth rate of phytoplankton in the sea. these include light intensity, day length, temperature, and nutrient supply. given t h e large seasonal variability that exists at high latitudes, it is likely that the extent to which each of these four variables determines the growth rate may fluctuate. for example in the barents sea, which is between 70--80"n, the water temperature ranges over the year between 0 and 6"c, the day length ranges between 0 and 24 hours, midday incident photosynthetically avail able radiation ranges between 20 and 1000 p e , and the concentration of nitrate ranges m-2 s i between 0.1 and 1 2 p m o l kg-'. although the growth of phytoplankton is clearly influenced by this variability, there have been few, if any, pub lications describing the effects of all four vari ables light intensity, day length, temperature, and nutrient concentation upon growth rate. in this study a tentative description of the regu lation of phytoplankton growth by more than o n e or two environmental parameters is presented. through examination of data on growth rate and 164 d. a . kiefer & j . j . cicllen chemical composition obtained from the con tinuous cultures of phytoplankton where all four factors mentioned above have been varied. i t is suggested that there are strong patterns in the responses of phytoplankton to variations in tem perature. light, and nutrient limitation. this infor mation has been incorporated into a model that provides a reasonably satisfactory description of the relationship between the light absorption, chemical composition. and growth rates of phyto plankton. model many models of the growth of phytoplankton a r e energy budgets (ryther & yentsch 1957; w e b b et al. 1974; jassby & platt 1976; geider 1990) that describe growth as a function of incident irradiance; photosynthetic efficiency and the amount of carbon that must be synthesized to make another cell. while such models are very useful, they d o little to explain how environmental factors regulate growth and chemical composition of phytoplankton (cullen 1990). additional insight comes from descriptions of the effects of irradiance, day length, nutrients, and tempera ture on light absorption. photosynthetic efficiency. and chemical composition. although these effects have been described many times. (smith 1980; laws & bannister 1980: fasham & platt 1983; kiefer & mitchell 1983; osborne & geider 1986; geider 1987: falkowski e t al. 1985). a comprehensive description is still lacking. by examining experimental d a t a to specify how each environmental factor affects parameters of a simple model. this study aims at describing phytoplankton growth as regulated by light, tem perature. and nutrients. t h e conceptual model used to relate the rate of light absorption by phytoplankton t o t h e growth rate is based upon both a phenomenological description and a mech anistic description. t h e phenomenological description. which will be used t o analyze the data presented in the following section, simply states that the specific growth rate of phytoplankton is the product of the rate of light absorption by the cell and the quantum yield of cellular carbon fixation. more specifically, the following can be stated: g. which is the specific gross rate of photosynthesis and a dependent variable (units of d a y ' ) , is a function of independent variables: light intensity, e,]: photoperiod. r; temperature, t; and nutrient concentration, n . g is equal t o t h e sum of the specific growth rate. 1-1, and the specific respiration rate (bannister 1979). in this study the light regime is rectified; the lights are on (units of mol m-' day-i) for a fraction, r, of each 24-hour cycle; t is in units of "c; n is in units of mg-at m i . a p is the chlorophyll a-specific absorption coefficient (units of m' mg-') and is assumed here to be a constant. 6 is the ratio of cellular carbon to cellular chlorophyll a (units of mg-at c mg chl-i) and is a dependent variable. 4 is the quan tum yield (units of mg-at c mol-i) and is a depen dent variable. although the two dependent variables may be functions of all four independent variables, we will see that this is true only for 8; table of symbols 8. n . r. e,, ap. i # j ~ . ~ ~ . 9. h . fc fc . t.d 01 . '!it. jcc. a dependent \ariable as indicated by equation 7 . i s the gross specific growth rate of the cells a dependent varidbk. is the maximum. instantaneous. carbon specific rate of carbon fixation an independent lariahlc. i s the duration of the photoperiod as a fraction of d ?+hour day a n independent bariable. i s the light intensity during the photoperiod a constant. i5 the chlorophyll (1 specific absorption coefficient of the cell suspension a constant and t h u s independent of light intensit!. tcmpcrature. day length. and nutrient concentration. is the a dependent variahlc as indicated by cqudtions ( 5 ) and ( 8 ) . is the quantum yield of carbon fixation a dependcnt variable. i s the ratio of cellular carbon to chlorophyll o a dependcnt \ a n a b l e as indicated b) cqudtion ( 2 ) . 15 the maximum. light-limited. instantancoub. carbon specific a dependent \ariahle a r indicated b! equation ( 3 ) . i s thc maximum. light-limited daily. carbon specific rate of dependent lariahle. is the minimum steady state turnober time of the photosynthetic electron transport system a dependent \ariahie. 15 the mean. cffccti\c absorption crors-section of photosvrtem i i a dependent bariahle. is the ratio of the ccllular concentration of photosystcm i i to carbon a con\tant which depends upon the chemical composition of the cell. i s the ratio ot the number of carhon atnms maximum q u a n t u m bield of carbon fixation rate of carbon tixatinn carbon fixation fixed t o the numhcr of clcctronr p a s c d through t h e elcctron transport s p t c m phytoplankton growth and light absorbance 165 14 h a j p c h l * , 1 ‘ r a t ji, 7 o2 t 28 h 7 h20 t 3 h t 14 h 2 0 (3xixc7( p reaajons reactions chl aox 7 c 0 2 t n h 3 7 o2 t 28 h fig. 1 . a conceptual model of phytoplanktonic growth and rcgulation. variations in light intensity. photopcriod, temperature, and nutrient supply will cause changes in both the rates of energy transformations and the cellular concentrations of the components shown in the figure. these components are the photosynthetic unit. the electron transport chain. and the cnzymes of the dark reactions. the cellular concentrations of these three components are regulated so that the growth rate is maintained without excessive dissipation of energy @ varies with temperature and light intensity but is little affected by variations in day length and nutrient concentration. we represent the maximum, light-limited instantaneous carbon specific rate of carbon fix ation as fc (units of day-’): the maximum, light-limited, daily carbon specific rate of carbon fixation is fc: (3) the mechanistic description is represented in fig. 1. photosynthetic growth is described in terms of the cycling of the pool of electron trans port compounds. symbolized by aox/arc, the oxi dized and reduced forms of the carrier pool. electrons are supplied to this pool by the activity of photosystem 11, symbolized by chlii/chl d , the ground and excited states of chlorophyll in the photosystem. although not shown in the figure, each photosystem consists of a n antenna and a reaction centre. photosystem i is not shown but is assumed to be under metabolic control (foyer et al. 1990) and does not restrict electron flow. while rates of electron supply will depend directly upon the size and cellular concentration of the photosystems and upon light intensity, rates will also be regulated by day length, temperature, and nutrient concentration. although evidence is limited, it appears that the cellular concentration of the electron transport pool is proportional to the concentration of photosystem i1 (sukenik et al. 1987). electrons are lost from the electron transport pool by the assimilation of inorganic compounds such as carbon dioxide and nutrients. while the rates of electron assimilation will dep end directly upon the cellular concentration of the enzymes of the dark reactions and temperature, rates will also be regulated by day length, nutrient concentration, and light intensity. transformations of the system include the dissipation of free energy in photosystem i1 by fluorescence and heat production, the dis sipation of heat from the electron transport sys tem by short circuiting of electrochemical gradients, and the dissipation of heat and excreted compounds by the “photorespiratory” pathways of the dark reactions. of course, such dissipation causes reductions in the quantum yield of carbon assimilation. w e assume that the process of meta bolic regulation involves adjustments t o maintain growth rates and t o minimize the costs that are associated with dissipation. (for example see kie fer & e n n s 1976 and shuter 1979.) such regu lation can generally be achieved by adjusting the rate of supply of electrons from the light reactions with rates of utilization by the dark reactions. specifically, this is achieved by varying the cellular concentrations of all three components shown in fig. 1, photosystem 11, the electron transport pool, and the enzymes of the dark reactions. a t present we d o not have a complete mathematical formulation describing the steady state, optimized condition. a mathematical description of the relationship between light absorption and growth is most simply represented in terms of the cellular con 166 d . a . kiefer & j. j . cullen centration of photosystem 11. its effective absorp tion cross-section, and its minimum, steady state, turnover time. a similar derivation has been pre sented by bannister (1979). t h e minimum, steady state, turnover time of photosystem 11, t, is the minimum time required for the reaction center to process an electron under steady state conditions (myers & graham 1971). t h e time required for charge separation by the unit is many times shorter. t, which is a dependent variable (unit of days), can be defined as the quotient of the cellu lar concentration of photosystem i1 and the maxi mum carbon specific rate of photosynthesis: r = qll jce/ii. (4) q i i , a dependent variable (in units of m gm-at c), is the concentration of photosystem i1 normalized to cellular carbon (units of moles mg-at c ] ) . n, a dependent variable, is the maximum carbon specific rate of photosynthesis (units of d a y ] ) . jce, which is a constant, is the stoichiometric coefficient of the number of carbon atoms fixed per electron that is passed through the transport chain (units of gm-at c mole e l ) . increases in the concentration of reaction centers tend to increase the turnover time while increases in t h e maximum rate of carbon assimilation tend t o decrease the turnover time. if the time between the capture of photons by photosystem i1 is less than the minimum turnover time of the photosystem, the photosynthetic quantum efficiency will be reduced. this relationship is expressed by the poisson distribution function (dubinsky e t al. 1986; peterson e t al. 1987; cullen 1990): (5) @,,,, a constant, is the maximum photosynthetic quantum yield; its value can be measured when the time between each capture of a photon by the photosystem is much longer than the minimum turnover time. ui1 is the effective cross-section of photosystem i1 (units of m2/mole) (ley & mauzerall 1982). the mean specific absorption coefficient. ap, is assumed to be contributed solely by the photo synthetic pigments of photosystems i and 11. if the effective absorption by the two photosystems is equal, o n e writes: @ = @ma, ( ~ ~ x p ( u i i te"))/uii rew by appropriate substitution within equations 1, 1. 5 , 6. o n e eliminates the two dependent variables. n l l and ull and obtains an equation for gross specific growth rate in terms of two constants, @,,, and ap, two independent variables, eo and r, and two dependent variables, i3 and 8: g = nt (1 -exp( -ap &,axeo/n 8)). (7) the quantum yield is g = no (l-exp(-a, $ma, eo/n * 8 ) / a p eo. (8) equation (7) is the exponential form of photo synthetic response curve. 8ii/a,@,,, is ik, g 8 is p i . if it is assumed that a p and $i,,, a r e constants, then variations in quantum yield that a r e effected by temperature, day length, a n d nutrient con centration must result from changes in the product no. a s mentioned earlier, it appears that this product is sensitive to changes in light intensity and temperature but not to changes in day length and nutrient concentration. growth and light absorption in cultures the laboratory studies used to examine t h e model presented above provide information on changes in two (g and 8 ) of the three dependent variables which are effected by variations in light intensity, day length, temperature, and nutrient supply. two studies which describe the steady state growth of skeletonema costatum will now be examined. o n e study by yoder (1979) examined the cellular concentration of chlorophyll a and growth rate of cells limited by light intensity and temperature. t h e other study by sakshaug et al. (1989) examined cellular concentration of chloro phyll a and growth rate of cells limited by light intensity, day length, a n d rates of nutrient supply. cultures in these studies were grown a t 15°c. it will be seen that g, n, a n d 8 vary with tempera ture, nutrient concentration, light intensity, and day length. it will also be seen that although the product n8 varies little with day length and nutrient concentration, it does vary with tem perature. thus, only light intensity and tem perature effect the steady state quantum yield of carbon assimilation. yoder (1979) grew skeletonema costaturn in turbidostat a t five temperatures (0, 5 , 10, 16, and 22°c) and at five light intensities. although cultures were also grown under a number of dif ferent photoperiods, values for the ratio of cellu lar carbon to chlorophyll u were reported only for phytoplankton growth and light absorbance 167 2.00 .1.60 -1.20 f -0.80 -0.40 * clchl 1growth rate 10.00 8.00 6.00 0 4.00 2.00 fig. 2. variations in specific growth rate, p (d-i). and the cellular ratio of carbon to chlorophyll, l9 (gm-at c gm chl-', of skeletonema costatum caused by variations in temperature. the five cultures were grown under light intensities of about 130 pmol m-* ski and a photoperiod of 12 hours. ._ . - 6.00 5.00 4.00 e 3.00 . . - 0.00 l 0.00 - t 0 .0.90 0.60 p 0.30 0.00 a 12-hour light and 12-hour dark cycle. sakshaug et al. (1989) grew skeletonema costatum con tinuously by daily dilution with a medium with an elemental composition that ensured nitrogen limitation. the cultures were maintained at 20°c, at six light intensities, ranging from 12 to 1200 pe * m-2 s-l, 3 photoperiods, 6 h light, 14 h light, and 24h light, and from 4-6 rates of dilution. the matrix of light intensities, dilution rates, and photoperiods was not complete. both studies include measurements of the temperature, light intensity, day length, specific growth rate, p, and the ratio of cellular carbon to chlorophyll a , 8. the data from these two studies have been analyzed by introducing values for the measured independent and dependent variables into equation (7). ap has been assigned a value of 0.016 m2 mg chl-' and a value of 0.10 g-at mol-'. since neither g nor the specific rate of 5 10 1 6 2 2 temperature respiration in the dark was measured, we assumed that g was equal to p and that dark respiration was only a small fraction of p. this assumption is questionable for cultures grown at very low light intensities or very short photoperiods. growth rates and cellular concentrations of chlorophyll a figs. 2, 3, 4, and 5 summarize the changes in growth rate and cellular chlorophyll a con centration that occurred with limitation by the four independent variables, light intensity, day length, temperature, and nutrient supply. tem perature limitations (fig. 2) causes decreases in growth rate that are accompanied by increases in the ratio of cellular carbon to chlorophyll a . such decreases in growth rate have been interpreted to result from decreases in the maximum specific i .a c/chl -.growth rate t 1.20 168 d . a . kiefer & j . j . ciilleri 1 .1 c i c h l growth fate 1 i 5 .. 1 2 -0.9 fig. 4. variations in specific growth rate. p ( d i ) . and the cellular ratio of carbon to chlorophyll. tj (gm-at c gm caused by variations in photoperiod, r. the three cultures werc grown at 0 6 o . 3 chl-i). of skeleronernu costalum 0 o 1s"c and under a light intensity of 0.25 0 . 5 8 r activity of enzymes of the dark reactions. limi tations by light intensity (fig. 3) cause decreases in growth rate that are accompanied by decreases in the ratio of cellular carbon t o chlorophyll a . growth rate declines with eo because the cellular concentration of chlorophyll a does not increase sufficiently with decreasing intensity. limitations by day length (fig. 4) cause decreases in growth rate that are accompanied by little change in the ratio of cellular carbon to chlorophyll a . since the instantaneous rate of cellular light absorption remains constant for the three photoperiods, the decreases in growth a r e simply caused by decreases in the daily rate of light absorption. limitations by rates of nutrient supply (fig. 5) cause decreases in growth rate that are 1 .oo 100pmol m-' s k i and with a rapid wpply of nutrients. accompanied by increases in the ratio of cellular carbon t o chlorophyll a . growth rates and maximal daily rates of photochemistry the data from the two studies can b e further analyzed by examining the relationship between the specific growth rate of the cultures, p, and the cell's maximal daily capacity to supply electrons, fc of equation (3). in t h e case of temperature and light limitation t o growth the relationship is complicated by a n absence of linearity. as shown in fig. 6, growth rate is a curvilinear function of fc. furthermore. this relationship is clearly a function of temperature; temperature decreases 5 0 t \ ~ ',, e 30 t fig. 5. variations in the cellular ratio of carbon t o chlorophyll. h (gm-at c grn c h l l ) , of skeleronernu cosfurum caused by variations in >pccific rates of nutrient supply. t h c culture3 were grown a t 15°c. at the light intcnsitics 2 0 + 40 i "'l c* c-.-.----_ i 0 2 0 4 0 6 0 8 1 1 2 i 4 shown (pmol m : 5 l ) . and under a u photoperiod of 24 hours. 0-' phytoplankton growth and light absorbance 169 rate. variations fig. 6. p. variations of in skeletonemu cellular. in specific daily costaturn capacity growth with of ( d a y 1 p 0.50 1.00 1 electron supply, fc of equation 3. the grown at the temperatures shown in variations between cultures that were 0.00 *.o0 t 1 _ _ ..@.@ 0 t=o xt=5 * t=10 + t=16 * t=22 [3x ~ _ _ . ... ~ ~~~~ ~ ~ .. . ,-.~~~~ ~ . -., .. cause decreases in rates of electron supply that saturate growth. it is apparent from this figure that a t 5°c a daily rate of electron supply of 0.5 d ' is sufficient t o meet a rate of assimilation of about 0.6 d-i. a t 22°c a daily rate of electron supply of 2.0 d-' is needed t o meet maximal daily rates of assimilation of about 1.8 d-'. in the case of limitations t o growth by light intensity, day length, and nutrient supply, the relationship appears t o b e linear. a s shown in fig 7, when skeletonema's growth rate at a given light intensity is plotted as a function of its daily capacity for photochemistry, the relationship is linear despite changes in day length and rate of nutrient supply. t h e slope of this line, which in fig. 7. variations in spccific growth rdtc, p. of skeletonemu costaturn with variations in cellular. daily capacity for electron supply. fc of equation (3). the variations bctwecn those cultures that were grown under the light levels, e,, (pmol m-? s-i). shown in the legend were caused hy variations in both rates of nutrient supply and photoperiod. the temperature was 15°c. 0 '.i 1 fact is the proportional to quantum yield, increases with increasing light intensity. quantum yields and growth rates t h e variations in quantum yield implied in figs. 6 and 7 are explicitly presented in figs. 8 and 9. when the quantum yields for growth at a given light intensity are plotted as a function of growth rate, there is evidenced a clear distinction between the adaptation to limitation by tem perature and the adaptation t o limitation by either day length or rate of nutrient supply. as shown in fig. 8, decreases in the temperature-dependent growth rate a t a given light intensity are 0 s 170 d . a . kiefer & j . j . cullen 0 0 4 . 0.02 0 00 0 50 1 0 0 1 5 0 u ( d a y 1 ) accompanied by decreases in quantum yield. each of the five categories of light intensity display a trend of decreasing yield with decreasing growth rate. one also notes by comparing the five cat egories that quantum yields tend t o decrease with increasing light levels. decreases in growth rate at a given light level effected by decreases in nutrient supply or day length d o not appear to be accompanied by decreases i n quantum yield (fig. 9). an exam ination of the six categories of light levelsindicates that in four of the six categories there is little or no covariation between quantum yield and growth rate. the two exceptions are the categories of the 4 2.00 lowest light levels, 12 and 41 ymol m-* d ' , where decreases in quantum yield appear to parallel decreases in growth rate. again, it can be noted that quantum yields decrease with increases in light levels. capacity for instantaneous electron supply and assimilation the final analysis of the two studies of ske letonema consisted of introducing values for eo, r, and 8, into equation (7). the equation is then solved for n , the maximum, instantaneous, specific rate of carbon fixation, by introducing 004 t i 0 0 2 4 0 4 0 fig. 8. variations in the photosynthetic quantum yield, i#j (gm at c e-i). of skeletonema costaturn w i t h variations in specific growth rate. p. the variations between those cultures that were grown under the light levels. 6, (pmol m * s-i). shown in the legend were caused by variations in temperature. the photoperiod was 12 hours. a * o fig. y. variations in the photosynthetic quantum yield. i#j (gm w i t h variations in specific growth rate. p. the variations between those *i at c e ' ) . of skeletonema costaturn * o ; 0 0 0 0 cultures that were grown under the " light levcls. e,, (pmol m ' s ' ) . shown in the legend were caused by variations in nutrient supply and 0 2 0 . 4 0 6 0.8 1 1.2 1.4 photoperiod. the temperature was ( d a y 1 ) 15°c. phytoplankton growth and light absorbance 171 significantly greater than the rate of change in photochemistry. while at 15°c and above, the specific capacity for electron supply is comparable to the specific capacity of electron assimilation; at 0°c the capacity for supply is about three times greater than the capacity for assimilation. the large decreases in quantum yield with decreases in temperature are explained by the differences between the two slopes. decreases in nutrient supply (fig. 11) cause decreases in both the capa city to supply and assimilation electrons. however, in the case of nutrient limitation, decreases in capacity for supply are paralleled by decreases in assimilation. thus, unlike tem perature adaptation, adjustments of the light and dark systems to nutrient limitation help to main tain the constancy of the quantum yield. decreases in light intensity cause decreases in the cellular instantaneous capacity to supply elec trons but have little effect on the capacity to assimilate electrons (fig. 12). thus, quantum yields increase with decreasing light levels. unfor tunately, values of ll calculated from equation 7 for light limitation are too variable to allow us to confidently conclude that there is no trend. on the other hand, there is abundant evidence that quantum yields increase with decreasing light levels, and thus cellular capacity for electron supply must drop more rapidly with light level than cellular capacity for electron assimilation. finally, unlike decreases in light intensity, decreases in day length cause increases in both 4.00 3.00 ~ ( d a y l ) 2.00 1.00 4 ' 0 0 2.00 i i c 0.00 i 0 5 i 0 i5 2 0 2 5 temperature fig. 10. variations in the cellular, instantaneous capacity for electron supply by the light reactions, fc of equation (2):and the instantaneous capacity for electron assimilation by the dark reactions, n. with variations in temperature. the five cultures were grown under light intensities of about 130 pmol m-* s-' and a photoperiod of 12 hours. values of 1 for g. changes in ll with temperature, light level, day length, and nutrient supply are then compared with changes in maximum instan taneous rates of photochemistry, fc, defined in equation (2). such a comparison provides insight into the differences in adaptation to the four environmental variables. decreases in tempera ture at a given light level and photoperiod (fig. 10) cause decreases in both the maximal rates of photochemistry and maximal rates of assimilation. of most importance is the rate of change in assimilation with temperature which is 5.00 t 0.00 j i 0 0.2 0.4 0.6 0.8 1 i .2 p ( d a y l ) fig. 11. variations in the cellular, instantaneous capacity for electron supply by the light reactions, fc of equation 2, and the instantaneous capacity for electron assimilation by the dark reactions. n. with variations in specific rates of nutrient supply. p. (p = dilution rate). the six cultures werc grown under a light intensity of about 100 pmol m 2 s ' and a photoperiod of 14 hours. t 16 .' r0.5 0.00 i 0 4 0 8 0 120 160 200 e o ( u e m . 2 ~ i ) fig. 12. variations in the cellular, instantaneous capacity for electron supply by the light reactions, fc of equation (2). and the instantaneous capacity for electron assimilation by the dark reactions, n. with variations in light intensity, e,). the five cultures were grown at 16°c and under a photoperiod of 12 hours. 172 d. a . kiefer & j. j. cullen i 4 03s eo 1w o o a 8 0 do 0 20 0 4 0 0 6 0 0 8 0 i00 r fig. 13. variations in the cellular. instantaneous capacity for electron supply hy the light reaction\. fc of equation ( 2 ) . and the instantancous capacity for electron assimilation hy the darh reactions. n. u i t h \ariations in photo-pcriod. r. t h e three cultures were grown at iyc under light intensities of ahout 1001~mol m ' 5 ' and at a dilution rate of 0 . 3 5 d ~ ' . the cellular instantaneous capacity to supply and assimilate electrons (fig. 13). since changes i n both capacities parallel each other, photosyn thetic quantum yields a r e little affected by changes i n day length. these results indicate that adaptation to day length is to a large extent inde pendent of adaptation to light intensity. a r k n o w l e d g e m e m . this work was sponsorcd by both the oceanic processes branch of the national aeronautics and space administration (nagw-317 and nagw-2072) and the biological oceanograph) program of the office of n a v a l research (n~xx)14-ry-j-30xi. nowii-8y-j123'). and no(k)i4 89-j10661. references bannister. t . t . 1979. a general theor! of \[cad) state p h l t o plankton growth in a nutrient saturated mixed layer. l i i n n o l . oceanogr. 14. 3x6-30 1 cullcn. j. j iyvi on model, of growth and photosynthesis in phgtoplanhton d e e p s e u res. 3 7 . m7-683 gcider. r. j . ly90: t h e relationship bctwccn stead! state phhtoplankton growth and photos)nthcsis. liinnol. ocenn ugr 35. 971 duhinsky. z . falkowski. p . c . b w y m a n . k 1986 light hdr\tsting 2nd utilization h! phytoplankton. planr cell phys i , > / . 17. 133.11349. f a l k o ~ s k i . p . g . dubinsk!. z . b wyman. k . lyx5: growth irrrdiancc relationships in phytoplankton lrinnol oceun 30, 3 1 1-321 fasham. m. j . r. & platt. t. lyx3: photosynthetic response of phytoplanktcm to light: a physiological model. proc. ,7. soc. l o n d . ,719. 355-370. fo!cr. c . furhank. r . . llarhinson. j . ti horton. p . iyyw t h e mcchaniimh contrihuting to photosynthetic control nf clcctron transport of carbon assimilation in leaves. phoro. r r , . 11. x3-ilml. geider. r . j . lyx7: light a n d temperature dependcncc of the carhon to chlorophyll a ratio in microalgac and cyanohactcria: implications for physiology and growth of phytoplankton. a'ew phyrologsr 106. 1-34. jasshy. a . d. 8; platt. t . 1976: mathematical formulation of the relationship between photosynthcsis a n d light for phyto plankton. lininol. oceanogr. 21. 5 4 c 5 4 7 kicfer. d . a . & enns. t. 1976: a steady state model of light. temperature. and carbon limited growth of phytoplankton. pp. 31%336 in canale, r . p . (cd.): m o d e l i q of biochemical prticesses i n aquaric sysfems. a n n arhor science. ann arbor. michigan. kicfer. d. a . & mitchell. b. g . 1983: a simplc, steady state description of phytoplankton growth based on absorption cross scction and q u a n t u m cfficiency. linrtiol. oceanogr. 28. l l ( k 7 7 6 . laws. e . a . b bannister. t. t. 1980: nutrienta n d light-limited growth of tho/assiosira fluoiufilis in continuous culture with implications for phytoplankton growth in thc occan. limnol. oceanojir. ls. 457173 lc). a . c. 8: mauzerall. d c. 1982: absolute absorption cross-section for photosystcm i1 and the minimum quantum requirement for photosynthesis in chlorellu uulguris. biorhim biophys. arru 680. 95-106. m y e n . j . & g r a h a m . j. 1971: t h e photosynthetic unit in c h l o r d l a measurcd by repctitivc short rashcs. pianr physrol. 48. 2x2. oshornc. b . a . & gcidcr. r . j 1986: effcct of nitrate-nitrogen limitation o f photosynthesis of thc diatom phueodacfylum rrrcornurum bohlin (bacillariophyceae). plunr cell enuiron. petcrson. d . h . . pcrry. m . j.. bencdla. k . e . & talbot. m. c. iyx7. phytoplankton productivity in relation to light intcnsity: a simple equation. esruar. cousr. shelfsci. 24.813-832. rythcr. j . h . 8. ycntsch. c. s . ly57: t h e estimation of phyto plankton production in thc ocean from chlorophyll a n d light data litntiol oceanogr. 2 . 281-286. sahshaug. e . . kiefer. d a . & andrcscn. k . iyry: a steady state description of growth and light ahsorption in the marine planktonic diatom skeleronema cosrurum. l i m n o l . oceanogr. 34. lyb205. shuter. b ly7ya model of physiological adaptation in uni cellular algac. 1. theor. biol. 78. 51f552. smith. r. a . 1980: t h e thcorctical basis for estimating phyto plankton production and specific growth rate from chloro ph!ii. light. a n d temperature d a t a . ecul. modelling 10. 243 2 6 . . sukenik. a , . bennett. j. & falkowski. p . g . ly87. light sdturatcd photosynthesis q limited by clcctron transport or carhon fixation'? biochim. biophvs. acra 8yl. 205-215. wchh. w l . newton. m . & starr. d . 1074: c a r b o n dioxidc exchange of alnrrs rubra. a mathcmatical model. oecologiu (berlrnj 17. 2x1-2yi yoder. j . a . 1y7y: effect of tempcrature on light-limited growth and chemical composition of skeleronetna cosfarurn (bacil lariophyccae) 1 . p/iyco/. i s . 362-370. y. 617-625. the little auk a l l e alle polaris of franz josef land: a comparison with svalbard a l l e a. alle populations l. stempniewicz, m . skakuj and l. iliszko stempniewicz, l., skakuj, m. & iliszko, l. 1996: the little auk alle alle poluris of franz josef land: a comparison with svalbard alle a . alle populations. po/ar research 15(1), 1-10, breeding biology, nestling growth and development, and biometry of the little auk alle une poluris were studied in franz josef land. a total of 103 adult birds were measured, 60 in the field and 43 in the st. petersburg museum. the development of 16 chicks was compared with that of alle a . alle chicks from spitsbergen. a t particular stages of development, both adults and nestlings of a . a . pofuris are larger than those of a . a . alle. in franz josef land the breeding season is more extended and less synchronised than that of svalbard. the majority of the little auks in the studied colonies in franz josef land nested on steep rocky cliffs, possibly as an adaptation to the severe climatic conditions and heavy mammalian predation in subcolonies located on accessible mountain slopes. glaucous gulls lurur hyperboreus exerted negligible predatory pressure. this study confirms the existence of morphologically distinguishable populations of the little auk on franz josef land and svalbdrd, supported by recent studies of climatic and oceanographic conditions in the two areas that parallel the morphological differentiation. lech stempniewicz, michuf skakuj und lech iliszko. department of vertebrate ecology und z o o f o ~ y . university of gdunsk, legion6w 9, 80-441 gdunsk, poland. introduction there are several examples of intrageneric dif ferentiation in the alcidae. for example, the genus uria has two closely related sister species, the common guillemot uria aalge and the briinnich’s guillemot u . lomvia. although their breeding ranges overlap widely, u . aalge tends to be boreal and u . lomvia tends to be polar. morphology, biology, food and behaviour are very similar though some differences exist, especially where the ranges overlap (salomonsen 1944; storer 1952; spring 1971; bbdard 1985; strauch 1985; birkhead & nettleship 1987a, b, c). closely related species are also found in the genera cepphus and fratercula, but these are geographically separated. the pacific ocean is inhabited by two cepphus species and two fra tercula species, whereas the black guillemot cepphus grylle and atlantic puffin fratercula arc tics occur in the atlantic ocean. there are also several examples of intraspecific differentiation within the genera cepphus and uria. for instance, storer (1952) has recognised six subspecies of black guillernot, seven sub species of common guillemot and two subspecies o f briinnich’s guillemot. o n the basis of size, stenhouse (1930) described a . a. polaris, a subspecies of the little auk alle alle, as originating from franz josef land. the ten specimens measured by stenhouse (1930) showed greater mean body dimensions (wing length, bill length and width and tarsus length) than those of the nominate subspecies a . a. alle which inhabits greenland, novaja zemlja and svalbard. since stenhouse’s (1930) paper, rus sian workers have collected and measured forty additional specimens from franz josef land and two from severnaja zemlja. the latter area is conjectured t o be a breeding area of subspecies polaris (dement’ev 1951; kozlova 1957; flint & golovkin 1990). until the present, the taxonomic position of little auks from these regions has remained uncertain and has been questioned (bcdard 1985). the aim of this study was to compare measure ments of adults and to analyse growth and devel opment of nestling little auks which inhabit svalbard (spitsbergen and bjclirmya) and franz josef land, where the subspecies alle and polaris, respectively, breed. aspects of the little auks’ breeding biology were also studied and compared. the results of this study may be useful in under standing patterns and processes of intraspecific differentiation in the little auk. 2 l . sternpniewicz et al. materials and methods biometrical data were obtained during three expeditions to franz josef land (21 august-7 september 1991, 15 august-5 september 1992, and 17 a u g u s t 4 september 1993). fifteen birds were collected in august 1991 in the colony at rubini rock (hooker island, 80" 47"). forty one birds were collected in august 1992 (34 at hooker island; 3 at prince george land, 8@ 81"n, 2 at northbrook island, 80"n 51'e and 2 at kane island, 81"n). four birds were collected in august 1993 at brady island (80"n). in total 60 individuals were measured in the field, including 14 netted and 46 shot for parasitological, toxi cological and food content analyses. in addition one of the authors, m. skakuj, measured 45 specimens which had bee housed for ca. 60 years in the collection of the institute of zoology of the russian academy of sciences in st. petersburg. the specimens included 43 adult little auks from franz josef land and 2 from severnaj a zeml j a. the little auks from spitsbergen (n = 99) were caught and measured during five expeditions to hornsund (77"n): 15 j u n e 4 september 1974,27 june-9 september 1975,13 may-20 august 1980, 30 july-27 august 1983, and 10-13 august 1992). the results have been published in part in an earlier paper (stempniewicz 1981). during the expedition to bj@rn@ya, 5-30 july 1994,272 little auks, including 219 adults and 53 subadults, were netted and measured in the colony at alfredfjellet (74" 15'n, 19" 03'e). subadult birds were dis tinguished from adults by external features such as colour and wear of primaries, secondaries, wing coverts and tail-feathers (roby et al. 1981; bradstreet 1982; bcdard 1985). measurements of subadult birds were excluded from the inter population comparisons. measurements were taken in the field by l. stempniewicz. all birds collected were thoroughly examined and then (shot birds) sectioned in the laboratory. age (two groups: subadults, birds in their second calendar year, and adults, older birds) and sex of birds were determined. sex determination was only possible for shot birds, measurements included body mass (with accuracy to l g ) , wing length (naturally folded wing and maximally flattened and stretched wing, adapted to little auks from svensson 1975), bill length (from tip to feather ing), head length (from bill tip to occiput; measured only in b j@m@ya birds), tail length (from root to tip of longest tail-feathers, when naturally folded, adapted to little auks from svensson 1975) and tarsus length (with accuracy to 1 mm). egg biometry is based on 99 eggs measured in spitsbergen, 15 eggs measured on bj@rn@ya, and 18 measurements from franz josef land taken from gorbunov (1932). the maximal length (l) and breadth (b) of eggs were measured and then volume index (v) was calculated using formula v = n / 6 * lb2/1000. chick growth and development were studied in august 1992 in the colony at rubini rock, hooker island. measurements of wing, bill, tarsus, tail and body mass were taken and plu mage development described every second day in the nestlings from 16 marked nests. other data about chick development as well as little auk breeding biology in spitsbergen were taken from earlier papers (stempniewicz 1980, 1981, 1986). statistical comparisons were made using a t-test, assuming normal distribution of data and equal variances of the samples. moreover, breeding phenology (dates of egg hatching, fledging of the young), activity rhythm (attendance at colony, feeding) and predation by glaucous gulls larus hyperboreus (number and percent of successful attacks) were studied and compared in the three areas (spitsbergen, b j ~ r n @ya and franz josef land). for methodological details see stempniewicz (1986, 1995). results measurements of adult and subadult birds table 1 presents statistics of measurements of adult little auks from hornsund (spitsbergen), bj@rn@ya and franz josef land. the last were separated into those taken on birds in the field and those from museum skins. subadult birds were not included in table 1, as they are sig nificantly smaller than adults. fifty-three subadult birds measured in bj@rn@ya differed significantly from adults (n = 212-219) in all body measure ments (t-test, 2-tailed p < 0.005), except for tarsus length (p = 0.32). there was, however, a considerable overlap in all measurements between the two age groups. sex-related dif ferences in adult body size were not evident (t-test, 2-tailed p > 0.05), except for body mass of the spitsbergen birds (df = 18, p < 0.001). the little uuk alle alle polaris 3 table 1. statistics of measurements of adult little auks alle alle from spitsbergen, bj0rn0ya and franz joscf land. body mass in g, length measurements in mm. wing nat. = naturally folded wing. sec table 2 for results of statistical tests. area spitsbergen bjmneya franz josef land franz josef land spitsbergen bjornoya franz josef land p r a m joscf land spilsbergcn bjyirncaya f l a w joaef land franz josef land spitsbergen bjornoya franz josef land franz josef land spitsbergen bjarnclya franz jmef land franz josef land spitsbergen bjornoya franz josef land franz josef land sample variable mean sd rangc n field mass 163.0 11.35 134.(&192 .5 94 field 157.8 10.53 133.f.ll96.0 212 field 202.3 12.48 174.(&230.0 56 museum field wing nat. 120.9 3.27 114.(&129.0 94 field 120.4 2.47 113.0-129.0 219 field 128.0 3.83 116.c-136.0 58 museum ~ field wing max. 124.6 2.51 121.(l127.0 5 field 124.8 2.64 118.0-133.5 217 field 133.3 3.73 122.u-141.0 59 museum 131.6 3.07 124.0~139.0 41 field tail 33.6 2.46 27.0-38.0 88 field 34.4 1.59 30.c39.0 219 field 38.3 1.24 35.u-41.0 41 museum field bill 15.9 0.71 14.0-17.5 88 field 15.3 0.82 13.0-17.5 217 field 17.4 1.19 14.7-19.5 57 museum 15.9 1.03 i4.(&18.0 32 field tarsus 21.8 0.81 2 0 . s 2 3 . 5 94 field 21.4 0.86 16.5-23.5 214 field 23.1 0.84 21.4-25.5 51 museum 21 .6 0.93 20.(&23 .o 42 ~ note: data arc not segregated by sex as a majority of the birds were not scx-determined. however, small sample of sex-determined birds makes the comparison difficult. in general, birds from franz josef land were heavier and larger than those from svalbard. evi dent differences in measurements (taken in the field) between birds from svalbard and those from franz josef land have been found (t-test, p < 0.001). moreover, little auks from bj@rn@ya were lighter and had shorter bill and tarsus than those of spitsbergen (table 2). skin measurements of franz josef land birds showed intermediate values, presumably d u e t o shrinkage and somewhat different methods of measuring live o r freshly dead birds versus skins, making it difficult t o compare the two kinds of samples. as a result, wing length (maximal length) of t h e skins was significantly shorter than maximal wing length of birds caught and measured in t h e field (franz josef land). also, bill length and tarsus length were significantly shorter in franz josef land skins than in those measured in t h e field. moreover, skins from franz table 2. differences in measurements (taken in the field) o f adult little auks alle alle from spitsbergen, bjornoya and franz josef land: body mass in g, length measurements in mm. wing nat. = naturally folded wing. see table 1 for data. area variable t p (2-tailed) bjorneya mass -3.92 0,000 versus wing nal. -1.47 0.141 spitsbergen wing max. 0.17 0.866 tail 3.24 0.001 bill -6.71 0.000 tdrsus -3.49 0.000 bjornoya mass -27.02 0.000 versus wing nat. -18.42 0.000 franz josef land wing max -19.90 0.i)ol) tail 14.66 o.m bill 15.72 0.000 tarsus 12.29 0.000 spitsbergen mass -19.74 0.000 versus wing nat. -12.26 0.000 franz josef land wing max. -5.09 0.000 tail -11.37 0.000 bill -9.20 0.000 tarsus -8.95 n.ooo 4 l. stempniewicz et al. table 3 . differences in measurements of adult little auks alle alle from spitsbergen, bj0rn0ya and franz josef land (taken in the field and in the museum). wing nat. = naturally folded wing. body mass in g, length measurements in mm. area (sample) variable t p (2-tailed) bjarngya (field) versus franz josef land (museum) spitsbergen (field) versus franz josef land (museum) franz josef land (field) versus franz josef land (museum) wing nat. wing max. tarsus bill wing nat. wing max. tarsus bill wing nat. wing max. tarsus bill -25.58 -14.64 -1.37 -4.04 -17.84 -4.87 1.04 0.12 -5.12 2.53 1.72 6.12 0.000 0.000 0.172 0.000 0.000 0.000 0.301 0.904 0.000 0.013 0.000 0.000 note: wing length in skins was taken (as far as possible) as maximum wing length josef land did not differ significantly from sval bard specimens measured in the field as regards bill length and tarsus length (spitsbergen) and tarsus length (bjornoya) (table 3). multivariate analysis showed that any set of two variables measured in the field clearly dis criminates the little auk populations from franz josef land and svalbard (anova, p < 0.001). figs. 1 and 2 illustrate discrimination of the two populations by combining body mass and wing length, and wing and bill length. eggs and chicks of the eggs measured, those from franz josef land were the largest, those from b j ~ r n 0 y a were t h e smallest, and the eggs from spitsbergen were intermediate in size. the differences are not stat istically significant. the samples are, however, body mass (9) relatively small. differences are more evident in egg breadth than length (table 4). this study is the first to address the devel opment of little auk chicks in franz josef land. the material we have obtained permits us to make general comparisons with spitsbergen nestlings. little auk nestlings in franz josef land attained significantly higher mean values of body mass and wing bill, tarsus and tail lengths in subsequent days of their lives than pitsbergen chicks (t-test, p < 0.05). the curves, however, have similar slopes, suggesting the same mode of chick growth and development in either locality (figs. 3 and twenty-five percent of the chicks observed in franz josef land belonged to the white-bibbed form and another 25% showed intermediate plu mage with ash-grey throats. these figures are much higher than in the case of nestlings studied 4). fig. 1 . body mass maximal wing length relationship in adult little auks alle alle from franz josef land and b j ~ r n 0 y a . dark ovals contain mean values and standard deviation ranges. the little auk alle alle polaris 5 fig. 2. maximal wing length bill length relationship in adult little auks alle alle from f r a u josef land and bj0rnqya. dark ovals contain mean values and standard deviation ranges. table 4. little auk alle alle egg measurements. length and breadth in mm, volume in cm3. area variable mean sd range franz josef land length 49.29 1.85 45.%52.5 (1914; n = 18) breadth 34.63 1.17 32.8-36.8 volume 31.00 2.87 26.3-36.0 spitsbergen length 48.99 1.88 45.0-54.4 (1974-75; n = 99) breadth 33.91 0.87 31.8-35.9 volume 29.49 2.19 24.634.7 b j q r n ~ y a length 48.53 2.61 43.6-53.7 (1994; n = 15) breadth 33.68 1.76 28.9-36.6 volume 29.01 4.25 19.1-37.6 in hornsund, spitsbergen (10%) (stempniewicz 1989). phenology fresh eggs have been found in franz josef land as early as 9 june and as late as 14 july (egg laying span 35 days) (gorbunov 1932; demme 1934). egg laying in hornsund in 1974 and 1975 covered only 15 days. it started about ten days later (18 june in 1974) and was completed about ten days earlier (3 july in 1975) (stempniewicz 1981). hatching has been observed in franz josef land as late as in the first days of august i.e. about 10 20 days later than in hornsund (norderhaug 1980; stempniewicz 1981). in 1992, timing of hatching in the colony at rubini rock was calculated to span the period 31 july-7 august, based on growth and developmental features of 16 nestlings studied during the period 16 august-3 septem ber. in franz josef land, birds began to leave fig. 3. comparison of the little auk chick body mass growth (mean 5 sd) in franz josef land (n = 1 4 1 6 ; for chicks older than 23 days, n = 7-9) and spitsbergen (n = 4 4 5 4 ; for chicks older than 24 days. 1 3 5 7 9 11 13 15 17 19 21 23 25 27 n = 9-37; data from sternpniewicz 1980). age (days) 6 l . stempniewicz et al. localilvlseason 120 ~ elm 1 100 h e e 5 80 v m c q, m (i 60 40 3 20 1 3 5 7 9 11 13 15 17 19 21 23 25 27 the colony about 20 days later than in spitsbergen, i.e. o n 28 august (fig. 5). females apparently left the colony earlier, leav ing the males to take care of the young during the chick's final days in the nest and during fledging. twenty-three of 31 (74.2%) adult little auks shot and sex-determined between 16 and 26 august fjl, 1914,30-31 i fjl, 1992 bjerrnerya, 1994 hornsund,l983 hornsund,l980 hornsund,l975 hornsund, 1974 hornsund, 1965 hornsund,l964 hornsund, 1963 fig. 4. compariwn of the little auk chick wing length growth (mean ? sd) in franz josef land (n = 14-16: for chicks older than 23 days, n = 7-9) and spitsbergen (n = 11-31; data from stempniewicz 1980). ' 1991/1992, and all 27 adult birds shot in the vicinity of the colony later in the two seasons (i.e. between 27 august and 7 september) were males. in the second half of august, adult little auks started moulting the black breast feathers (breed ing plumage) which gradually changed into white feathers (winter plumage). on 19 august 1992, 1 10 20 30 10 20 30 10 20 30 10 june july august sept. fig. 5 . timing of egg laying, hatching and fledging of young little auks in svalbard and franz josef land (horizontal lines ranges with numbers of nests controlled: vertical lines medians). data for spitshergen are from norderhaug (1980) and stempniewicz (1981, 1986, 1995; unpubl. data), for b j ~ r n ~ y a from stempniewicz (unpubl. data) and for franz josef land from gorbunov (1932). demme (1934), and stempniewicz (1993: unpubl. data). the little auk alle alle polaris 7 forty-one of 183 birds (22.4%) surveyed in the colony showed distinct signs of breast feather moulting. w e 0 m z 2 e m c w q m ? ? ? ? 0 0 0 0 '19"09 0 1 0 " n n b l l n" n n e e e z a e e a z a e e z a discussion the original description of the subspecies from franz josef land, alle a. polaris, was based on a small sample (stenhouse 1930). this study con firms the existence of a morphologically dis tinguishable population of the little auk on franz josef land. the existence of two distinct popu lations in svalbard and franz josef land is dif ficult t o explain because these two land masses are both in the same high-arctic zone (salomonsen 1972). recent studies, however, do show dif ferences in climatic and oceanographic conditions between these two areas that may parallel this morphological differentiation. the climate in franz josef land is more severe due to the impact of two cold currents (makarov and arctic currents) which flow from the north, and to the relatively weak influence of the relatively warm novaja zemlja current which brings remnants of atlantic water from the south (weslawski 1993). nevertheless, the distance separating these two archipelagos is small and easily covered by little auks which migrate thousands of kilometres each year (norderhaug 1967). partial interchange of birds between the two areas is very likely and differences in body size between the birds from franz josef land and svalbard are not absolute (table 1, figs. 1 and 2 ) . morphological differences may be maintained or strengthened by divergent migratory habits related to recent glacial history. it is conceivable that the larger of the two subspecies, having a surface : volume ratio that is more adaptive in severe climate, could have evolved in a refugium along the arctic coast basin, whereas the smaller subspecies was restricted to the south. larger body size, however, usually involves higher energy demands. franz josef land is known for its numerous polynyas which remain open during the entire winter season (zenkevie 1963). abun dant food resources and feeding close to the col ony may increase feeding efficiency (wesiawski et al. 1994). the use of distinct wintering areas may have reinforced the differentiation. there is some evidence of differences in migratory habits between svalbard and franz josef land populations. the svalbard population 8 l . stempniewicz et al. winters in southwest greenland waters (nor derhaug 1967), whereas the wintering grounds of the franz josef land population are not known. considerable numbers of little auks winter in the northern region of novaja zemlja. as the little auk population in novaja zemlja is estimated at several thousand pairs only (golovkin 1984), the birds wintering there may originate from franz josef land (rutilevskij & uspenskij 1957; butev 1959). the early arrival of little auks at their breeding grounds in franz josef land (february and early march; gorbunov 1932) suggests that they winter relatively close by; some birds may even winter in the polynyas of this region. the discovery of little auks in the bering sea, along with evidence that some of these birds belong to an established population (bcdard 1966; breckenridge 1966; holmes 1968) and the fact that these specimens have been assigned both to alle a. alle and a . a . polaris (sealy et al. 1971) does not clarify the situation. however, day et al. (1988) concluded that all the little auks found in the bering strait belonged to the niminative subspecies. two birds from severnaja zemlja in the collection of st. petersburg museum differ so much in their measurements that one could be assigned to the subspecies polaris and the other to alle. some differences in body size are also found among a . a. alle specimens from different areas (tables 1 and 5). interpretation of these dif ferences is difficult because of the various meas uring techniques used. however, even when measurements were obtained by the same method, differentiation of the little auk popu lations within the svalhard archipelago could be confirmed. birds from b j ~ r n ~ y a tend t o be smaller than those from spitsbergen (table 2 ) . there were no statistically significant dif ferences in the size of eggs from the three areas (bj~rncbya, spitsbergen and franz josef land), but the mean values corresponded with the dif ferences found in body size. however, these dif ferences should be interpreted with caution due to the small sample sizes (bjcbrncbya and franz josef land) and different sample years (table 4). the majority of the little auks in the colonies visited in franz josef land occupy holes and crevices in the walls of rocky cliffs, the same breeding habitat occupied by black guillemots. this may lead to interspecific competition for nesting sites. on several occasions we observed little auks displaying black guillemots from cliff ledges and even chasing them in the air. in franz josef land only small colonies of little auks were observed in easily accessible talus slopes, which is not true for little auks in svalbard. the apparent preference for cliffs to talus slopes in the visited colonies in franz josef land can partially be explained by the easy accessibility of the cliffs which allow earlier breeding, a factor which is crucial in the extremely short franz josef land summer, and protection from mammalian predation which is high in the talus colonies. at least one arctic fox alopex lagopus was observed almost permanently penetrating the little auk col onies at the foot of rubini rock, and polar bears u r s w maritimus were noted to cause considerable losses in these colonies (stempniewicz 1993). predation by the glaucous gull was, however, negligible both in the vulnerable cliff colonies and in the talus colonies. in 1992 eight glaucous gull pairs nested at rubini rock. they hunted mainly young brunnich’s guillemots and kittiwakes rissa tridactyla. during 143 hours of observation, only 27 incidents of patrolling gulls were observed in the little auk colony at rubini rock, and only one successful attack on a little auk fledgling. in spitsbergen, glaucous gulls persecute little auks much more intensely (stempniewicz 1995). in franz josef land, little auks begin breeding about 10 days earlier and leave the colony about 15-20 days later than they d o in svalbard. thus, their breeding season seems t o be more protracted and less synchronised than in svalbard. the total duration of the little auk breeding period (com prising eggs and chicks present in the colony) was calculated to 67 days in spitsbergen and to 86 days in franz josef land. a lower synchronism in franz josef land is probably a consequence of less intense predation by glaucous gulls and shorter feeding ranges there, which tend to make synchronisation of colony attendance and fledging less essential for survival (stempniewicz 1986; weslawski et al. 1994). the intense activity of mammalian predators which damages little auk nests at different breeding stages may cause a lengthening of the egg-laying period (replacement clutches). however, great caution is needed when interpreting phonological differences due to prominent interannual climate variations in the high arctic. demme’s (1934) suggestion that young little auks leave the breeding colony in franz josef land in winter plumage was not confirmed by us. however, the percentage of white-bibbed the littfe auk alle alle polaris 9 nestlings was much higher than that found in spitsbergen (stempniewicz 1989). white-bibbed young birds may elude the first pre-basic moulting involving lower face and throat areas and thus save time and energy after fledging. parent little auks start moulting while they are still feeding their chicks. moulting during breeding creates an additional energy demand and is only possible under conditions of easily available food and numerous feeding grounds close to the breeding colony. by starting to moult breast feathers before breeding is completed, adult little auks also save time and energy later. both these features of young and adult a . a. polaris may be considered as adaptations t o the extremely severe and short summer season in franz josef land. acknowledgements. we would like t o thank our colleagues from the expeditions lo franz josef land (rus-nor-pol 91 93) and bjornoya 94 for their help during field work. special thanks are due to j . m . weslawski from the institute of oce anology pas. the norwegian polar institute kindly allowed us to use the cabin in revdalen, bjornoya. financial support was received from the university of gdansk (grant nr. bw/1140-5 00872 and 805). we are grateful to three anonymous referees for english language assistance and constructive comments to the manuscript. references bedard, j . 1966: new records of alcids from st. lawrence island, alaska. condor 68, 50s506. btdard, j . 1985: evolution and characteristics of the atlantic alcidae. pp. 1-51 in nettleship, d. n. & birkhead, t. k. (eds.): the atlantic alcidae. academic press, london toronto. birkhead, t . r. & nettleship, d. n. 1987a: ecological relation ships between common murres, uria aalge, and thick-billed murres, uria lomuia, at the gannet islands. labrador. i. morphometrics and timing of breeding. can. j . zool. 65, 1621-1629. birkhead, t. k. & nettleship, d . n. 1987b: ecological relation ships between common murres, uria aalge, and thick-billed murres, uria lomuia, at the gannet islands, labrador. 11. breeding success and site characteristics. can. j . zool. 65, 163&1637. birkhead, t. r. & nettleship, d . n . 1987c: ecological relation ships between common murres, uria aalge, and thick-billed murres, uria lomvia, at the gannet islands, labrador. 111. feeding ecology of the young. can. j . zool. 6 5 , 1638-1649. bradstreet, m. s . w. 1982: pelagic feeding ecology of dovekies, alle alle, in lancaster sound and western baffin bay. arctic 35, 126140. breckenridge, w. j . 1966: dovekie on diomede island, alaska. auk 83, 680. butev, w. t. 1959: zimovka ptic na severe novoj zemli (birds wintering i n the north of novaja zemlja). ornitologia 2 , 9 % 101. 1988: distribution and subspecies of the dovekie in alaska. condor 90, 712-714. dement’ev, g. p. 1951: otrjad cistiki. pticy souetskogo sojuza (alcidae. birds of the soviet union). sov. nauka, moskva, pp. 169-240. demme, n . p . 1934: ptieij bazar na skale rubini (birds’ colony on the ruhini rock (hooker island, franz josef land). trudy arkt. inst. 11, 55-86. flint, v. e. & golovkin, a . n. 1990: pticy sssr. c‘istikovye b i r d s of the ussr. alcidae). nauka, moskva. 207 pp. golovkin, a. n. 1984: sea birds nesting in the ussr: status and protection of populations. pp. 473486 in croxall, j . p . , evans, p. g. h. & schreiber, r. (eds.): seabirds of the world: their status and conseroation. international council for bird preservation. cambridge, england. gorbunov, g. p. 1932: pticy zemli franca josifa (birds of franz josef land). trudy arkr. inst. 4 , 1-234. holmes, r. t. 1968: a dovekie on the pribilov islands, alaska (plautus aiie record). condor 70, 86. kozlova, e . v. 1957: podotrjad tistikouye, fauna sssr, pticy (suborder, alcae, fauna of ussr, birds), vol. 2 . moscow leningrad. pp. 114-143. lovenskiold, h. l. 1954: studies on the avifauna of spits bergen. norsk polarinst. skr. 103. 131 pp. norderhaug, m. 1967: trekkforhold, stedstrohet og par dannelse hos alkekonge pa svalbard. fauna 20(4), 236-244. norderhaug, m . 1980: breeding biology of the little auk (plautus alle) in svalbard. norsk polarinst. skr. 1 7 3 , 1-45. roby, d . d . , brink, k . l. & nettleship, d . n . 1981: measure ments, chick meals and breeding distribution of dovekies (alle alle) in north-west greenland. arctic 3 4 . 241-248. rutilevskij, g . l. & uspenskij. s . m . 1957: fauna ptic i mlekopitajuseih centralnoj arktiki (fauna of birds and mam mals of the central arctic). trudy. arkt. inst. 205, 5-18. salomonsen, f. 1944: the atlantic alcidae. the season and geographical variation of the auks inhabiting the atlantic ocean and adjacent waters. g0reborgs kunlinga vetenskaps och vitterhetssamhalles handlingar, serie b 3, 1-138. salomonsen, f. 1972: zoological and ecological problems in artic birds. proc. intern. ornithol. congr. 15, 25-77. sealy, s. g., bidard, j . , udvardy, m. d . f. & fay, f. h . 1971: records and zoogeographical notes on the birds of st. lawrence island, bering sea. condor 73, 322-336. spring, l. 1971: a comparison of functional and morphological adaptations in ihe common murre ( u r i a aalge) and thick billed murre (uria lomuia). condor 73, 1-27. stempniewicz, l. 1980: factors influencing the growth of the little auk, piaurur alle (l.), nestlings on spitsbergen. ekol. pol. 28, 557-581. stempniewicz, l. 1981: breeding biology of the little auk, plautus alle in the hornsund region, sw spitsbergen. act0 ornithol. 18, 141-165. stempniewicz, l. 1986: factors causing changes in the rhythm of attendance of the little auks, plautus alle (l.), at a colony during the breeding season in svalbard. ekof. pol 34, 247 263. stempniewicz, l. 1989: dovekie juvenile plumage dimorphism. colonial waterbirds 1 2 , 123-125. stempniewicz, l. 1993: the polar beef ursus maritimus feeding in a seabird colony in frans josef land. polar res. 12, 31 36. stempniewicz, l. 1995: predator-prey interactions between glaucous gull larus hyperboreus and little auk alle alle in spitsbergen. acta ornifhol. 29, 155-170. day, r. h . , d e gange, a . r . , divoky, g . j . & troy, d. m. stenhouse, j . h. 1930: the little auk alle alle (polaris sub 10 l . stempniewicz et al. species nov.) of franz josef land. srottish nuturulisr 182, 47-49, storcr, r . w. 1952: a comparison of variation. behavior and cvolution in the bca bird genera uriu and cepphus. u m u . &/if. puhl. zoo/. 52. 121-222. strauch, j . g . jr. 1985: the phylogeny of the alclrlue. auk 102, 520-539. svcnswn, l . 1975: ident$cution guide to european p u s w i n e s naturhistoriska riksmuseet. stockholm. westawski, j . m. 1993: the comparison of weqt spitshergen and frans josef land marine coastal ecosystems. sfudia i materiafy oceunologicrne ( s i m o ) 64, 331-341. weslawski, j . m, stempniewicz. l. l galaktionov k . 1yy4: summer diet of seabirds from the frans josef land archi pelago, russian arctic. polar res. 13, 173-181. zenkevic, l. a . 1963: biobgiu morej sssr (biology of the seas of the ussr). nauka, moscow. 735 pp. fluxes of c 0 2 and ch4 in high latitude wetlands: measuring, modelling and predicting response to climate change nicolai s. panikov this review covers selected aspects of recent international efforts to measure and model greenhouse gas emission from northern wetlands, to identify the environmental factors that control gas emission, and to investigate wetlands' responses (particularly with respect to gas emission) to global change. both bottom-up and top-to-bottom approaches, based respectively on local observations plus inventory of gas fluxes and inverse modelling of global circulation, agree on the size of the high latitude (> 60"n) contribution to global methane, which should be about 13% or 70 tglyear. it has been shown that winter and spring fluxes are an essential part in the annual budget of ch4 and especially coz exchange (varying from 5 to 50%). soil micro-organisms were shown to be able to respire during winter even at 16°c. in comparison to aerobically respiring organisms, anaerobic methanogenic bacteria were less active in frozen soil, although they are subjected to significant stimulation by soil freeze-thaw cycles. the absence of immediate coupling of methanogenesis with plant photosynthesis implies that substrates for methane formation are derived from peat decomposition rather than from root exudation. n . s. panikov, institute of microbiology, russian academy of sciences. prospect 60-let octyabrya 712, moscow 11781 1, russia. introduction increases in the concentration of greenhouse gases since pre-industrial times (i.e. since 1750) have led to a positive radiative forcing of climate, tending to warm the surface and to produce other changes in climate (houghton et al. 1995). global circula tion models (gcms) predict an increase in global mean temperature of 3°c by the end of next century; they also indicate that high northern latitudes will warm more than the global mean in winter (walsh 1991; maxwell 1997). warming is indicated by: reduction in sea ice extent and snow cover, particularly in spring (robinson & dewey 1990); lowering of surface-based temperature inversion depths (bradley et al. 1993); retreat of mountain glaciers; and rise of near surface air temperature by 0.3-0.6"c since the late 19th century (houghton et al. 1995). the northern ecosystems are a significant source of greenhouse gases. even if the present day fluxes are modest, the large size of the reserves of conserved organic matter implies that potential, warming-induced coz, ch4 and non-methane hydrocarbons (nmhc) fluxes could be very large (vourlitis & oechel1997). warming and drying of tundra areas could result in massive losses of c 0 2 . there are data indicating that some tundra areas have already shifted from net carbon sinks to sources in the last 10-15 years (oechel, vourlitis et al. 1995). warming of areas which remain wet could stimulate methane formation and increase already large methane releases to the atmosphere. trace gas fluxes are also expected to be sensitive to changes in plant and microbial community distribution, which might be driven by perturba tions of biological equilibrium and have a counter intuitive response. trace gas fluxes vary in a complex way across space and over time; gas formation and transport involve various physiological and physico-chemi cal mechanisms. the most evident gaps in this field were identified as follows (see iasc-gcte working group's fate [feedbacks from arctic terrestrial ecosystems] document, accessible via the internet): deficiency of flux data on gas, panikov 1999: polar research 18(2), 231-244 231 especially on winter emissions from northern eurasia and the high arctic; poor understanding of the mechanisms behind observed fluxes at a physiological level (formation of belowground substrates, microbial, enzymatic, and microfaunal interactions, etc); the lack of generalized inte grated approaches, and long-term and spatially extensive measurements. the progress achieved recently by the international efforts of arctic scientists to fill in the indicated gaps is summar ized here. contribution of northern wetlands to global methane budget one of the most important objectives is to determine circumpolar c 0 2 and ch4 fluxes, quantify the rates of gas emission in different parts of the arctic and reveal the trends associated with global climatic change. there are two complementary approaches to this: bottom-up and top-down approaches. the first one is based on the long-term monitoring of gas emission via a network of field stations or sites that cover the main types of habitats. at its simplest. the total circumpolar emission, e is estimated as a sum: n i=i e = c a ~ f ~ where n is the number of the types of northern ecosystems differentiated in terms of easily mapped features like vegetation, soil properties, relief, geomorphology, etc.; a is the area of each type; and f is characteristic annual emission. the sets of a j and fi are assumed to be constants. instead of sum, one can use the more or less complicated functional dependence of f on environmental parameters, say on soivair tem perature, water table level, mineral content in soil, etc., to evaluate regional emission (bouwman et al. 1999). bottom-up approach: geographical coverage, variation in spatial and temporal fluxes a thorough survey of available data is beyond the scope of this paper; readers are referred to reviews by harris et as. (1993) and vourlitis & oechel (1997). the most intensive studies and the longest observations of gas fluxes have been obtained in north america, mainly the alaskan north slope (whalen & reeburgh 1988, 1992; oechel, vourli tis et al. 1995; baldocchi et al. 1996; oechel, cowles et al. 1994, 1995). currently these sites are the main focus of the atmospheric radiation measurement (arm) programme, supported by the us department of energy, and the us national science foundation land-atmosphere ice-interactions (laii) flux programme (weller et al. 1995). there are similar programmes funded by eu and national igbp programmes of several european countries (lteef-finland, beri, dan ish trace gas flux study, congas. etc.). in northern eurasia, extensive measurements of gas emission were initiated in the late 1980s. these were either short-term measurements across geographical transects or long time series of flux at single sites. the first approach is illustrated by chamber measurements of c 0 2 and ch4 fluxes across the russian arctic (christensen, jonasson et al. 1995). the second approach is realized in a number of field stations where gas fluxes are measured mainly during the summer season (zimov et al. 1993: panikov, sizova et al. 1995; panikov, glagolev et al. 1997). the general tendencies of spatial and temporal flux variation can be formulated as follows. first, there are evident temperature related variations: even within northern wetlands the highest net fluxes occur in warmer soils, the maximal values being attained in the boreal zone. seasonal variation also follows a temperature dynamic curve, although winter, autumn and spring emis sion are often essentially non-zero (see below). second, there is always enhanced emission from wetlands patches covered by vascular plants (eriophorum, carex, menianthes) as compared with pure sphagnum lawn (due to the effects of vascular transport of methane and higher produc tivity of graminoids as compared with mosses). third, variations of the water table affect co;? and ch4 emission in an opposite ways, methane fluxes being stimulated and carbon dioxide suppressed by a rising water table. however, the range of fluxes varies so widely that uncertainty in regional and global estimates remains large and very much dependent on site-specific features of each parti cular study. for example, extensive measurements by various techniques over hudson bay lowland (roulet et al. 1994) lead to the conclusion that 238 fluxes of coz and ch4 in high latitude wetlands northern wetlands are a modest source of atmos pheric methane, with an average july emission of 10-20 mg chjdlm’ and a regional flux no more than 0.5tgch4 per year. on the other hand, source tg1yea.r global emission* tubk 1. contribution of northern area (above 60”n) to global methane emission (based on hein et al. 1997). % from alaskan wet meadow and shrub/tussock tundra have an average summer emission up to 100-700 mg chdd/m2 (whalen & reeburgh 1992), extrapolating to 42 rt 26 tg ch4/year. a similar or even higher emission level was found in the boreal zone both in minnesota (dise 1992; melloh & crill 1993) and in west siberia (panikov, sizova et al. 1995; panikov, glagolev et al. 1997). a modelling approach based on empirical relationships between ch4 fluxes, environmental factors and npp provides some compromise between the two cited extremes, say, 20 ? 16 tg chdyear from northern wetlands globally (christensen, prentice et al. 1996). however, the uncertainty in regional/global esti mates is very disappointing and calls for alter native ways to solve the problem. an inverse modelling approach is one such solution. top-down approach: inverse modelling information on temporal and spatial variation of ch4 and co? emissions from soils is deduced from observational data on gas mixing ratios in air (obtained via a network of noaa/cmdl field stations scattered over the globe, mainly i n oceanic regions far from industrial sources). these data are fitted to a 3-d atmospheric transport model, which is combined with a tropospheric background chemistry module and accounts for all essential sources and sinks of gas. the model is validated against an “internal standard,” such as methyl chloroform. for this volatile man-made com pound, the chemical industry has reliable data on its annual production, as well as the kinetics of’ its elimination from the atmosphere through photo chemical reactions involving the same oh radicals as in the case of atmospheric methane (hein et al. 1997). the inverse modelling method optimizes the agreement between calculated and observed methane mixing ratios by adjusting the magnitudes of the various methane sources and sinks. the adjustment is constrained by specified a priori information. e.g. methane emission from wetlands and rice paddies is allowed to vary in seasonal dynamics, while methane from anthropogenic wetland 28.7 12.3 animals 2.6 3.1 landfills 2.2 5.6 fossil sources 40.7 38.9 sum 74.3 12.9 biomass burning 0 0 *540 tglyear sources (fossil fuel escaping from oil wells, natural gas pipelines, coal mains, etc.) is not. additional constraints come from 13c/12c isotopic ratios of gas in the atmosphere, driven by isotopic fraction ation factor having different values for biological and abiotic catalysers. a similar approach was used to assess c 0 2 sources (fan et al. 1998). currently available results of inverse modelling (hein et al. 1997) do not deviate significantly from data obtained by bottom-up approaches (table 1). the contribution of high latitude areas ( > 60”n) to global methane levels was less than 13% or 70 tg/ year, and northern wetlands are responsible for emissions of less than 30 tg of ch4 per year. such conclusions seems to contradict the latitudinal gradient pattern of atmospheric methane with a maximum over the arctic. however, this maxi mum can be attributed to a smaller sink (slower removal of ch4 in photochemical reactions with oh at lower temperatures), rather than by more intense gas emission from northern terrestrial as compared with mid-latitude sources. at the same time, hein et al. admit that simulation of ch4 seasonal dynamics in arctic air was poor, reflect ing that some essential mechanistic considerations behind gas emission were missed. mechanistic understanding of biological and environmental control of gas emission to clarify such mechanisms we require a holistic view of the functioning of the whole ecosystem, including photosynthesis, respiration, c-flows between plants, micro-organisms and animals, as well as decomposition and conservation of soil organic matter (om), nutrient dynamics, water panikov 1999: polar research 18(2), 231-244 239 fig. 1. schematic representation of biological processes in wetland soil responsible for methane formation, uptake and emission. regime, etc. (fig. 1). methane is the end product of an anaerobic metabolic network, which starts with the hydrolytic split of plant litter polymers (lignocellulose, pectin). the next step is fermenta tion of monomeric soluble products into volatile compounds (fatty acids, alcohols, h2 and coz). fatty acids containing three or more carbon atoms are resistant to instant assimilation under anaerobic conditions, but are converted to acetate and h2 by enigmatic soil microbes called syntrophic bacteria. their functioning is permitted by the second law of thermodynamics only under conditions of contin uous removal of produced h2 and acetate (stams 1994). the removal is performed by methanogens and their competitors, acetogenic and sulfidogenic bacteria. under some environmental conditions (e.g. if sulphate content is high enough) methano gens are suppressed by their competitors and anaerobic soils do not produce methane. gases formed anaerobically move across a concentration gradient (molecular diffusion, ebullation or vascu lar transport) to atmosphere, being partly sca venged by methanotrophic bacteria occupying the aerobidanaerobic interface. all microbial cells are subjected to elimination by grazing protozoa. even a simplified scheme (fig. 1) illustrates a very important feature of the anaerobic metabolic network: ch4 formation proceeds through a number of alternative pathways and methane can be substituted by competitive end products (fatty acids, acetate or sulphide). this feature of anaerobic soil calls for adequately structured mathematical simulations aimed at understanding and predicting ecosystem dynamics under climate change (warming/cooling, soil flooding or drain ing, fertilization, etc.). it is not enough to relate methane emission to the water table level without considering the nutrient status of the soil environ ment and the possibility of one or several competing pathways. plant-microbial interactions it is well known that c 0 2 exchange in aerobic soils is entirely controlled by the carbon and nutrient 240 fluxes of c 0 2 and ch4 in high latitude wetlands 2500 “e 2000 p z i“ 0 1500 1000 ch4 source: decompositi of dead om ch,source: living plant (root exudates, sloughing ...) 0 2 4 6 8 10 days fig. 2. dynamics of methane formation in the peat soil under sedges (plotnikovo, west siberia) after clipping plants and enclosing the soil in a stainless steel cylindrical frame (28 cm diameter, 32cm long). during 10 days of anaerobic in situ incubation the peat water was sampled at different depths and analysed for dissolved methane content (panikov, unpubl. data). flows between the plant and microbial commu nities (panikov & gorbenko 1992). photosynthetic uptake of c 0 2 initiates plant growth (shoots and roots), as well as the formation of rhizodeposition (root sloughing and exudation) which is the main c and energy source for soil microbes. on the other hand, micro-organisms are the main suppli ers of n, p and hormones regulating plant growth. the immediate link between plants and soil methane is less obvious. do methanogens con sume root exudation products or do they utilize peat decomposition products? this question was addressed in a number of recent studies with ‘“c02 labelling of plants which traced the label in methane emitted from submerged soil to the atmosphere. clear-cut results were obtained with rice paddies (minoda & kimura 1994): incorpora tion of photosynthetically derived 14c to methane was highest (72-1 10%) in young plants and then declined to 13-17% at senescence. in our preliminary experiments with natural northern wetlands we came to the opposite conclusion (fig. 2): the prevention of photosynthesis by plant clipping or shading and the subsequent prevention of root exudation did not affect a steady rate of methane formation. in other words, we have not found any significant short-term response of methanogens to changes in photosynthetic activ ity. this indicates that anaerobic processes in wetlands are mainly driven by peat decomposition rather than by root exudation. temperature effects, cold season fluxes temperature stimulation of methanogenesis and methane emission is probably the main focus in the majority of ecological and biogeochemical studies of trace gas fluxes. the mechanism of such stimulation seems to be counter-intuitive. indeed, summer temperatures rise more in the top methanotrophic soil layer or, at least, should stimulate both methane formation and uptake. therefore, net emission (formation minus uptake) was expected to decline or remain more or less constant under soil warming. however, in reality, net ch4 emission is always accelerated by warming, indicating that methane formation is more responsive to temperature than methane uptake. although a molecular mechanism for such a phenomenon is still unknown, we have reliable estimates of empirical qlo coefficient that varies between 5-8 for methanogens and around 2 for methanotrophs. several recently published papers deal with winter fluxes and belowground processes in frozen soils. whalen & reeburgh (1988) noted in alaskan sites episodic release of ch4 amounting to 41% of the annual flux from moss-covered areas. winter ch4 emission from various bogs and fens were found to account for 4-21% of annual fluxes in minnesota (dise 1992) and 2-10% in the temperate poor fen in new hampshire (melloh & crill 1993). february fluxes of ch, in west siberia were 5.0 * 3.7 m g m p 2 per day, which corre sponds to 3.5 to 11% of annual budget (panikov, dedysh et al. in press). winter c 0 2 emission to the atmosphere was shown to be even higher: average values for the entire cold season (october-may) were 150 mg c mp2 d-’ in subarctic kolyma soils (zimov et al. 1993) and 300 and 80 mg c m-’ d-’ for moist tussock tundra and coastal wet sedge ecosystems, respectively (oechel, vourlitis & hastings 1997). the cold season loss of c then should be 20-70 g m-’, which is up to 80% of the total annual net loss. the reason for the difference in contributions of ch4 and coz winter fluxes to the annual budget stems first of all from the algebra behind flux calculation. indeed, the net panikov 1999: polar research 18(2), 237-244 24 1 0 2 4 6 incubation time, days fig. 3. dynamics of peat respiration ( c 0 2 formation) during winter sample incubation at -16 f 1°c: c 0 2 evolution rate in peat from 1-10 cm (1) and 10-20 cm (2). the deeper peat layers are not shown. the total flux (3) was calculated as the sum of respiration rates over all peat depths. annual coz flux is a difference between two high numbers: net c-flux = r ph = r,, + rwjn ph = (1 k2)r + kzr klr = (1 kl)r where r is total ecosystem respiration, ph is plant photosynthesis, and r,,, and rwin are summer and winter respiration, respectively. since r,,, ph (summer respiration is almost balanced by photo synthesis), then net coz flux is very much influenced by cold season emission, when ph = 0, even if the rwin > > r,y,,. for example, if k l = 0.9 and kz = 0.05 (i.e. winter respiration is only 5 % of the annual respiration as in the case of methane), then the contribution of winter to the annual net c02-flux would be very high anyway: r,i,/net co2 flux = kz/(l k l ) = 0.5 or 50%! the mechanisms of cold season emission are intensively discussed. some authors explain win ter fluxes by the mechanical release of c 0 2 from soil during ice formation (coyne & kelley 1971). oechel, vourlitis & hastings (1997) hypothesize that frozen soil retains the respiratory activity of cold-tolerant organisms; potential candidates are soil fungi, which display a wider temperature range of metabolic activity than bacteria (flanagan & bunnell 1980). zimov et al. (1993) assume -6 -3 0 3 6 9 incubation time, days fig. 4. the effects of freeze-thawing on soil methanogenic activity. peat sampled from 15-20 cm depth was incubated at 20°c for 6 days, then frozen (1) and allowed to thaw (t), with subsequent incubation at 20°c (panikov, dedysh et al. in press). peat was sampled in april ( i ) and july 1998 (2). uninterrupted activity of soil micro-organisms due to their self-heating; biogenic heat production can be viewed in biochemical terms as deliberate adaptive uncoupling of oxidative reactions from atp-generation to convert chemically usable energy to heat. we have recently obtained direct experimental evidence for this phenomenon (panikov, dedysh et al. in press). we have found that fresh samples of frozen peat soil incubated under laboratory conditions at a constant temperature of 16°c displayed very slow but steady respiration. this varied from 0.05 to 0.2 mg coz-c d-' dm-3, depending on peat sampling depth (fig. 3). although this activity was 200-300 times lower than summertime soil respiration, it was enough to support the observed in situ winter c 0 2 emission. there are at least three convincing arguments confirming that ob served coz evolution is caused by instant micro bial activity, but not diffusion of gas accumulated in soil crumbles during the warm season: 1) the dynamic pattern of coz evolution from frozen soil, which follows an asymptotic curve, approaches a low but constant steady gas forma tion rate, rather than a gradual decline to zero which would be expected from mechanisms based on release of accumulated co?. 2) the vertical distribution of the respiration rate 242 fluxes of coz and ch4 in high latitude wetlands along a profile of frozen soil has its maximum on the top, where highest biological activity occurs. it is clear that opposing mechanisms (release of accumulated gas) would require more intensive c 0 2 flux from bottom layers, where coz con centration is higher. 3) the proportionality between respiration rates of soils at low and high temperatures indicate that the forces driving the process are basically the same at both temperatures. other interesting effects observed at low temperatures are activation of soil respiration and especially high methanogenic activity. the thaw and subsequent peat incubation at 15°c acceler ated gas formation by one order of magnitude followed by a decline, approaching a steady state level (fig. 4). although the mechanism of freeze thaw activation needs further clarification, it was nevertheless possible to simulate the observed activation dynamics with a mathematical model, which accounts for the burst of microbial growth on nutrients released into soil from frost-damaged cells. acknowledgements. -this research was supported in part by the russian fund for fundamental research. grant nos. 96-04 49321 and 99-04-48725. and by the ec environment and climate programme (congas). references baldocchi, d.. valentini. r., running, s.. oechel, w. & dahlman. r. 1996: strategies for measuring and modelling carbon dioxide and water vapor fluxes over terrestrial ecosystems. glob. change b i d . 2(1l 101-1 10. bouwman, a. f.. derwent. r. g. & dentener, f. j . 1999: towards reliable global bottom-up estimates of temporal and spatial patterns of emissions of trace gases and aerosols from land-use related and natural sources. in a. f. bouwman (ed.): approaches to scaling of trace gas ,flnxes in ecosystems. pp. 1-26. amsterdam: elsevier. bradley, r. s., keimig, f. t. & diaz, h. f. 1993: recent changes in the north american arctic boundary layer in winter. j . geophys. res. 98(05), 8851-8858. christensen. t. r.. jonasson. s., callaghan, t. v. & havstriim. m. 1995: spatial variation in high latitude methane flux along a transect across siberian and european tundra environments. j. geophys. res. iood, 21035-21045. christensen, t. r., prentice. i. c., kaplan, j., haxeltine, a. & sitch. s. 1996: methane flux from northern wetlands and tundra. an ecosystem source modelling approach. tellrrs 43b. 652-661. coyne, p. 1. & kelley, j . j . 1971: release of carbon dioxide from frozen soil to the arctic atmosphere. natnre 234, 4 0 7 4 0 8 . dise, n. b. 1992: winter fluxes of methane from minnesota peatlands. biogeochem. 17, 7 1-83. fan, s., gloor, m.. s m i e n t o , j., takahashi, t. & mans, p. 1998: a large terrestrial carbon sink in northern america implied by atmospheric and oceanic carbon dioxide data and models. science 282(5388), 4 4 2 4 6 . flanagan, p. w. & bunnell, f. l. 1980: microfloral activities and decomposition. in j . brown et al. (eds.) an arctic ecosystem: the coastal tundra of northern alaska. pp. 291-335. new york: van nostrand reinhold. harris, r.. bartlett, k., frolking, s. & crill, p. 1993: methane emissions from northern high-latitude wetlands. in r. s. oremband (ed.): biogeocheniistrv of global change: radia tively active trace gases. pp. 4 4 9 4 8 6 . new york: chapman & hall. hein. r., cmtzen. p. j . & heimann, m. 1997: an inverse modeling approach to investigate the global atmospheric methane cycle. glob. biogeochem. cycles l l ( l ) , 43-76. houghton, j . t., meira filho. l. j., callander, b. a,, hams, n., kattenberg, a. & maskell, k. (eds.) 1995: climate change 1995. the science of climate change: contribution of working gronp i to the second assessment report of the intergovern mental panel on climate change. cambridge: cambridge university press. maxwell, b. 1997: recent climate patterns in the arctic. in w. c. oechel et al. (eds.): global change and arctic terrestrial ecosystems. pp. 2 1 4 6 . new york: springer. melloh, r. a. & crill, p. m. 1993: winter methane dynamics in a temperate peatland. glob. biogeochern. cycles 10(2), 247-254. minoda, t. & kimura, m. 1994: contribution of photosynthe sized carbon to the methane emitted from paddy fields. geophys. res. lett. 21, 2007-2010. oechel, w . c., cowles, s., grulke, n., hastings, s.j., lawrence, b.. pmdhomme. t., riechers, g., strain, b., tissue, d. & vourlitis, g. 1994: transient nature of co2 fertilisation in arctic tundra. nature 371, 500-503. oechel, w. c., vourlitis, g. & hastings, s. j. 1997: cold season c 0 2 emission from arctic soils. glob. biogeochem. cycles l l ( l ) , 163-172. oechel, w. c., vourlitis, g. l., hastings, s. j. & bochkarev, s. a. 1995: change in arctic c 0 2 flux over two decades: effects of climate change at barrow, alaska. ecol. appl. 5,846-855. panikov, n. s. 1999: understanding and prediction of soil microbial community dynamics under global change. appl. soil ecol. 11, 161-176. panikov, n. s., dedysh, s. n. & tarasov. a. l. in press: cold season ch4 and co2 emission from temperate peat bog (west siberia): winter fluxes and thaw activation dynamics. glob. biogeochem. cycles. panikov. n. s.. glagolev, m. v., kravchenko, i. k., mastepa nov, m. a., kosych, n. p., mironycheva-tokareva. n. p., naumov. a. v., inoue, g. & maxutov, s. 1997: variability of methane emission from west-siberian wetlands as rebated to vegetation type. ecol. chem. 6. 59-67. panikov. n. s. & gorbenko. a. j. 1992: the dynamics of gas exchange between soil and atmosphere in relation to plant microbe interactions: fluxes measuring and modelling. ecol. bull. 42. 53-61. panikov, n. s., sizova, m. v., zelenev, v. v., machov, g. a,, naumov, a. v. & gadzhiev, i. m. 1995: methane and carbon dioxide emission from several vasyugan wetlands: spatial and temporal flux variations. ecol. chem. 4 ( 1 ) , 13-23. robinson, d. a. & dewey, k. f. 1990 recent secular variations in the extent of northern hemisphere snow cover. geophys. res. lett. 17, 1557-1560. panikov 1999: p o l a r research 18(2), 237-244 243 roulet, n. t., jano, a,, kelly, c. a,, klinger, l. f., moore, t. r., protz, r., ritter, j. a. & rouse, w. r. 1994: role of hudson bay lowland as a source of atmospheric methane. j . geophys. res. 99, 1439-1454. stams, a. j. m. 1994: metabolic interactions between anaerobic bacteria in methanogenic environments. antonie van leeu wenhoek 66, 271-294. vourlitis, g. & oechel, w. c. 1997: the role of northern ecosystems in the global methane budget. in w. c. oechel et al. (eds.): global change and arctic terrestrial ecosystems. ecological studies 124. pp. 266-289. new york springer. walsh, j. e. 1991: the arctic as a bellwether. nature 352, 19-20. 244 weller g. et al. 1995: the arctic flux study: a regional view of trace gas release. j. biogeogr. 22, 365-374. whalen, s . c. & reeburgh, w. s . 1988: a ch4 time series for tundra environments. glob. biogeochem. cycles 2 , 399-409. whalen, s . c. & reeburgh, w. s. 1992: interannual variations in tundra methane emission: a 4-year time series at fixed sites. glob. biogeochent. cycles 6, 139-159. zimov, s . a,, zimova, g. m., davidov, s. p., davidova, a. i., voropaev, y. v., voropaeva, z. v., prosiannikov, s . f., prosiannikova, 0. v., semiletova, i. v., & semiletov, i. p. 1993: winter biotic activity and production of c 0 2 in siberian soils: a factor in the greenhouse effect. j . geophys. res. 98, 5017-5023. fluxes of c 0 2 and ch4 in high latitude wetlands landslides and relict ice margin landforms in adventdalen, central spitsbergen, svalbard takanobu sawagaki and takashi koaze sawagaki, t. & koaze, t. 1996: landslides and relict ice margin landforms in adventdalen, central spitsbergen, svalbard. polar research 15(2), 139-152. two characteristic landforms, landslide blocks and drainage channels, were investigated in adventdalen, central spitsbergen. the landslides in the middle reaches of adventdalen comprise large-scale bedrock slumps which form a hummocky surface on the south slope of arctowskifjellet. the fourteen recognised landslide blocks are divided into upper and lower sections, according to altitude. the drainage channels consist of tributary rivers to adventelva which flow in two distinct directions, either parallel with or oblique to the direction of the main river. glacial deposits were found to cover the ridges between these tributary channels. the upper and lower landslide divisions may indicate former positions of the ice surface, and the channels appear to have originated during the existence of lateral moraine ridges with high ice content. these geomorphological findings have allowed reconstruction of former ice marginal positions, and they strongly suggest the existence of stagnant ice or minor re-advance phases during the course of deglaciation in adventdalen. tukanobu sawagaki, laboratory of geoecology, graduate school of environmental earth science, hokkaido university, sapporo, 060, jupan. takashi koaze, department of geography, meiji university, kanda, surugadai, chiyoda-ku, tokyo, japan. introduction in the large valleys of central spitsbergen, such as adventdalen, reindalen and sassendalen, distinct moraines delineating the pattern of deglaciation have not previously been recognised except for a complex series of moraines outside of the mouth of isfjorden (ohta 1982; mangerud et al. 1992). additionally, it has been stated that younger dryas moraines seem to be completely absent in svalbard (salvigsen 1979) and that the ice dissipated rapidly in the warming climate of the early holocene age (feyling-hanssen 1955, 1965; forman 1989; mangerud et al. 1992). as most of the studies on the quaternary glaciation in svalbard are based on research along the coastal areas, where glacial till and uplifted former shorelines are easily found (e.g. boulton 1979; troitsky et al. 1979; mangerud et al. 1987; forman 1989; miller et al. 1989; mangerud & svendsen 1990; salvigsen et al. 1981; mangerud et al. 1992), the quaternary history of the inland area is less well understood. it is difficult to find thick glacial till layers due partly to the possible presence of former cold-based, non-scouring ice. in addition, the lack of historical record of glacial fluctuations and absolute ages for moraines and glacial deposits have prevented studies in the inland area up to now. the japanese geomorphological expedition to svalbard carried out field work in 1988 and 1989 (ono et al. 1991) and was followed by the japanese svalbard expedition in 1990. as part of the latter expedition, a geomorphological study was carried out in august 1990 and in the period of june-august 1991 to identify the geomorpho logical evidence for glacial fluctuations in ad ventdalen, an inland area of central spitsbergen. the investigated area is situated between the ice margin of dr~nbreen and the junction of foxdalen and adventdalen. two characteristic landforms, landslides and drainage channels were investigated. the causes and times of failure for the landslides were evaluated. regarding the drainage channels, this study shows how the distribution of till and channels allow reconstruction of the former ice margin landforms in the adventdalen area. as large-scale topographic maps suitable for the purpose of this study are not available, two basic maps on the scale of 1:10,000 and 1:25,000 with a contour interval of 10 m were drawn, using 140 t. sawagaki & t. koaze fig. 1 . location map of adventdalen, spitsbergen. present glaciers are shaded. inner squares indicate the sites of figs. 2, 6, 8 and 13. the. analytical photogrammetric system (wild aviolyt bc 2) of the national institute of polar research, japan. data on morphometry were obtained by interpretation of air photographs in the scale of 1:15,000 taken by the norwegian polar institute in august 1990. the study area adventdalen is an ese-wnw trending glacial valley which terminates in adventfjorden, a tributary to isfjorden, central spitsbergen, sval bard (fig. 1). the valley is approximately 45 km long and 4 km wide. the upper reaches of the valley are connected with sassendalen to the northeast and reindalen to the south through low passes at altitudes of about 400 m a.s.l., forming a network of interconnected valleys. the valley is surrounded by ice-capped mountains ranging in altitude from 1000 to 1100 m. the highest summit is that of mt. skolten (1128 m). dr~nbreen, the largest glacier, occupies the valley head, and other small glaciers terminate in the tributary valleys. adventelva, the main stream of this valley, drains westward from drqnbreen into adventfjor den. it has formed braided channels and an outwash plain in front of dranbreen. from the upper reaches to the middle reaches of the valley, the river has dissected late quaternary sediments and the underlying jurassic shale bedrock to form terraces about 1 0 m high which dominate the valley bottom. in the lower reaches of the river, the stream spreads out to form complicated braided channels. in the investigated area, three large tributaries in helvetiadalen, janssondalen and foxdalen flow into adventelva. wide alluvial fans have formed at their confluent points. polygons of various sizes have developed both on river terraces along adventelva and on the hill slopes. ice wedges were found beneath some of the polygons (svensson 1988; ono et al. 1991) and some pingos were present on the riverbed. few direct measurements of the permafrost thickness have been made in this area. according to the measurements reported by liestgl (1975), landslides and relict ice margin landforms 141 , 1 0 0 d contour line / fault dipstrike lan i fig. 2. distribution of the landslide blocks on the southern slope of arctowskifjellet (cf. fig. 1). the permafrost thickness on the southern side of adventdalen was 450 m. in summer, a seasonal thawed layer 40-100 cm thick was observed, and the active layer saturated by water collapsed in many places on the valley slopes. as this type of failure is limited to the surface, it is not discussed in this article. the bedrock geology of adventdalen is shown on a 1:100,000 map (major & nagy 1972). a major part of the investigated area is underlain by jurassic and cretaceous sedimentary rocks which dip gently towards the southwest. progressively older rocks are exposed from south to north. these deposits are lithologically divided into the janusfjellet, helvetiafjellet and carolinefjellet formations in ascending order. the janusfjellet formation consists predomi nantly of dark-gray shale and siltstone. the helvetiafjellet formation consists of a lower festningen member and an upper glitrefjellet member (parker 1967). the festningen member is a light-gray, fineto coarse-grained sandstone forming distinctive cliffs. the glitrefjellet mem ber is a mediumto coarse-grained sandstone interbedded with shale and siltstone. the caro linefjellet formation consists of shallow marine sediments with alternating beds of sandstone and shale (major & nagy 1972). the most characteristic structures in the studied area are two north-south trending anticlines, the skolten anticline and the tronfjellet anticline, which are separated by dronbreen syncline (major & nagy 1972; haremo et al. 1990). the skolten anticline in this area has a trend of about n160"e and a plunge of less than s'sse (haremo et al. 1990, fig. 6). in a river section along 142 t. sawagaki & t. koaze adventelva, the upper part of a duplex structure with a northward fold axis crops out (haremo et al. 1990). normal faults with minor (0.1-1 m) offset have been identified in the janusfjellet formation. haremo et al. (1990) suggest these as young faults associated with landslides. they note that cleavage and joints are generally not characteristic deformation structures and that joint orientation is highly variable in this area (haremo et al. 1990). fig. 3. landslide block location (no. 14) on the west of arctowskifjellet. fig. 4. idealised sketch of the internal structure and features of the landslide blocks. landslides identification of the landslides according to the geological map of the advent dalen area (major & nagy 1972), a multitude of smaller and larger landslides termed ‘landslips’ had occurred in areas where the mountain slopes were comprised of a combination of the janusfjel let and helvetiafjellet formations. these slopes landslides and relict ice margin landforms 143 table 1. features of the landslide blocks. no. area orientation length width base top height old new dh dl ( ~ 1 0 ~ ~ ’ ) (m) (m) (m a.s.1.) (m a.s.1.) (m) (m a.s.1.) (m a d . ) (m) (m) 1 12.61 s46e 400 400 430 572 142 600 550 50 2 6.15 s64e 280 200 380 480 100 600 480 120 3 7.03 s30e 370 150 300 450 150 600 450 150 4 15.12 s06e 550 275 210 390 180 600 390 210 5 7.77 s06w 55 150 230 390 160 600 390 210 6 34.42 s08e 730 500 430 623 193 600 500 100 7 20.12 s08w 270 675 400 450 50 500 450 50 8 16.06 slow 440 475 250 373 123 9 48.84 s46w 1010 600 380 587 207 540 450 90 10 6.28 w 320 200 410 520 110 11 20.11 w 550 425 360 480 120 520 450 70 12 15.56 s72w 470 450 250 360 110 13 21.19 s72w 670 350 270 410 140 540 400 140 14 48.02 s58w 730 780 230 380 150 540 360 180 no = number of each block. area = area of the block. orientation = downward orientation of the long axis of the block. length = the maximum horizontal length of the block. width = the maximum horizontal length of the block, right-angle to the orientation. base = altitude of the lowest point of the block top = altitude of the highest point of the block. height = the relative height of the block calculated by an equation: (height) = (top)-(bottom) old = the original altitude festningen sandstone. new = altitude of the festningen sandstone in the block. dh = the differential height between ‘old’ and ‘new‘ (vertical travelling height of the festningen sandstone). dl = the differential horizontal length between ‘old’ and ‘new’. 215 62.5 675 1000 825 325 300 325 200 700 875 fig. 5. vertical distribution of the landslide blocks. are commonly underlain by shale, which is loose been identified on the convex southeast to south and crumbles easily. conversely, sandstone, west facing slopes of arctowskifjellet (fig. 2). in especially the quartzitic sandstone of festningen the field, most landslides were recognised as slide member, is hard and remains as caprock forming blocks (as shown in figs. 3 and 4) with the cliffs. following characteristics: using aerial photographs together with detailed the inner stratification of massive sandstone field observation, fourteen landslide blocks have which forms the top of the block has not been 144 t. sawagaki kk t. koaze disturbed, and the block surface is tilted back toward the upper part of the slope at a gentle angle. the edge of the festningen sandstone generally forms a steep cliff. gentle slopes composed of shale occur in the middle part of the block. a number of sandstone blocks have fallen down from the cliffs and lie scattered on the slope surface. although the bedding in the underlying shale is difficult to identify, the bedding plane occasionally remains. in such cases, most of the bedding planes are complexly folded and faulted. a landslide on the highest part of the slope on the south of arctowskifjellet has the largest scarp in this area. the height of the scarp is about 150 m, and the slope angle is nearly 40”. the foot of the scarp is covered by talus and the landslide blocks spread downward from the talus slopes. on the blocks, sandstone layers of the helvetiafjellet formation tilt upslope to form small hillocks. this tilting results in a transverse depression between the landslide scarps and the blocks. both sides of the depression are smoothed by solifluction. positions of the festningen sandstone beds within the blocks were confirmed by field observation. they are good markers and indicate displacement of the landslide blocks. features of the individual blocks are listed in table 1. vertical traveling height (dh) and differential horizontal length (dl) of the festningen sand stone were calculated using the original altitude of the sandstone (old) and the current altitude of the sandstone (new). vertical distribution of the landslide blocks as shown in figs. 2 and 5, the landslide blocks may be divided into two groups according to their vertical distributions, an ‘upper block group’ (nos. 1, 2, 6, 9, 7, 11, 10) and a ‘lower block group’ ( 3 , 5 , 4 , 1 3 , 1 4 , 8 , 1 2 ) . the base zone of the upper block is higher than 360 m a.s.l., and the lower block extends to below 300 m a.s.1. the ‘height’ and ‘dh’ of the upper block group seem to be variable. however, the ‘base’ of the individual landslide blocks within the upper block group seem to be between 360 and 430 m. in the case of block no. 6, the base is undefined, because the lower part of the block seems to have been disturbed and is obscured by secondary landslides (nos. 3, 5 and 4). the bases of landslide blocks in the lower block group may be limited to between 210 and 300 m a. s. 1. in the upper block group, the festningen sandstone is commonly found in the middle, whereas in the lower block group, it occurs in the uppermost part of the block. the deformation structures and displacement of the festningen sandstone suggest that the lower block group originated from the upper block group as secondary landslides (fig. 5) causes of landslides the landslides in the studied area have been classified as ‘rock slumps’ (after varnes 1978). a rock slump is a type of slide characterised by a rotational component. the term ‘slide’ signifies the existence of a single surface or several surfaces of shear displacement. none of these features were recognised in the adventdalen landslides, but this may be because the shear planes occur at depth, below the ground surface, or because shear may have occurred within a diffuse zone. however, a backward rotational movement is indicated by the tilting sandstone strata on the blocks. rotation occurs due to forces that cause a turning moment about a point above the centre of gravity of the unit. the less firm shale underlying the sandstone has been pushed ahead forming lobate pressure ridges in front of the block. the valley walls of adventdalen are believed to have been eroded by glacial activity. however, the slopes in the studied area are not u-shaped, but rather form gentle hummocky shapes; helve tiadalen, a tributary of adventdalen, has the same shape. these hummocky slopes may have been produced by the landslides which were associated with the side wall steepening as a result of the former glacial erosion. the jurassic shale is loose enough to be denuded, while the sandstone remains on top of the shale. consequently, loading of the sandstone and over-steepening of the slope have occurred, resulting in the failure of the sandstone overlying the shale. in svalbard, most of the glaciers are subpolar glaciers (hagen 1987). subpolar-type glaciers reach melting point in high accumulation areas, below which continuous permafrost appears. thus, melt water sinks into the ground producing a groundwater stream which flows downwards under the permafrost layer (liestal 1975). the bedrock on the valley slopes should freeze after the glacier retreated, thus it is possible for the groundwater stream to act as slump surface landslides and relict ice margin landforms 145 between the upper frozen bed and the lower thawed bed. we assume three principle causes of the landslides in adventdalen: (1) a caprock structure, composed of helvetiafjellet sandstone above and janusfjellet shale below, causes loading of the sandstone onto the shale; (2) glacial erosion produces the over-steepening of the valley wall; and ( 3 ) the groundwater stream under the frozen bedrock has resulted in hydrologic change. time of occurrence owing to a lack of empirical evidence in the field, it is difficult to assess the exact time of the landslides and deposition of its surface materials. however, since glacial erosion is considered to be one of the causes of the landslides, the time of occurrence of the landslides should correspond to the deglaciation. in the middle part of the lobe of block no. 14 (fig. 2), the shale is exposed, striking n20"w and dipping 48"w. glacial striae were locally ob served on unweathered and polished surfaces (fig. 3 ) . the ssw orientation of the glacial striae fig. 6. recent glacial margin landforms in the upper part of janssondalen (cf. fig. 1). coincides with that of the current main drainage in adventdalen. the lobe was formed as a bulge in front of a sliding block, and the striae are believed to have been originally formed on the horizontal bedding plane of the shale before the landslide occurred. because shale is very susceptible to erosion, it is hard to believe that the shale could have survived another glaciation. therefore, the landslide blocks are not believed to have experi enced glaciation since formation of the striae. the landslides caused by deglaciation seem to have been intercepted by the glacier ice remaining in the valley. in fact, some of the landslides which are located along the present ice margin are indicated in the geological map of adventdalen (major & nagy 1972); for example, tellbreen and fangenbreen at the north of helvetiafjellet, arnicabreen to the east of arctowskifjellet. these landslides are commonly restrained by lateral moraines or glacier ice. the two groups of landslide blocks which are based on the two fixed base levels (fig. 5 ) can then be considered to indicate the former levels of the surface of the glacier ice. this means that the occurrence of the landslides coincides with two 146 t. sawagaki & t. koaze fig. 7. development of two glacier margin hillside channels during deglaciation. a. glacier advance forming the ice-cored moraines. b. thinning of the ice-core during glacial retreat. c. extinction of the ice-cored moraine remaining the superficial deposits. different stages of deglaciation. at first, after the surface of the glacier had dropped considerably to one level, the upper blocks slumped. later, when the ice surfaces further lowered, the lower blocks slumped from the upper blocks. ice marginal landforms recent ice marginal landforms in adventdalen the most distinct moraines around the margin of dr~nbreen and other glaciers in adventdalen are considered to have formed during the little ice age (e. g. warner 1989; mangerud & svendsen 1990; shiraiwa et al. 1991). as is usually the case in svalbard, these moraines are ice-cored. the gl~tfjellbreen and m~ysalbreen glaciers, which converge to the west of mt. skolten, show a typical example of present ice margin features (fig. 6). the moraine ridges in front of these glaciers are approximately 10 m high and have been cut by streams in several places. tributary stream courses on the valley walls have been blocked by the ice-cored lateral moraines of the glacier and diverted along the margins of the moraines, incising into the shale underlying the moraines and forming narrow, deep marginal channels (fig. 6). the outermost parts of the subpolar glaciers are frozen to the bed preventing the water from draining in and out. thus it is also likely that similar ice marginal channels along the high moraine ridges were formed at various times in the past. since these channels formed, the ice cores in the moraine ridges have melted and the ridges have decreased in height, leaving only surface deposits. once a channel was established, the stream continued to cut into the relatively soft shale bedrock. thus each channel was incised and remained long after the ice retreated, in contrast to the degraded ice-cored moraine ridges. flint (1971) presented an idealised sketch showing the development of glacier-margin hill side channels during deglaciation. in the present study, another idealised sketch is proposed based on the investigation of gr~tfjellbreen (fig. 7). this sketch shows that a pair of marginal channels develop on either side of the ice-cored moraine during a stagnation in the deglaciation. drainage pattern and distribution of glacial deposits in adventdalen the river system in the middle reaches of adventdalen shows a feather-like drainage pattern (fig. 8). the upper part of major tributaries and their branches are mainly aligned in a north-south direction according to slopes. however, major tributaries turn their courses in the lower part below about 200 or 300 m a.s.l., from north-south to northeast-southwest on the north side and to southeast-northwest on the south side of the valley, oblique to the general inclination of the valley walls. these stream channels join the main river channel at an angle between 45" and 90°, following former courses in their lowest parts. the tributaries on both sides are confluent to the main river at almost the same place, like a three pronged fork. topographic profiles presented in fig. 9 show that these tributaries flow at the same altitude on both sides of the main river and that the tributaries on each side make a pair. landslides and relict ice margin landforms 147 ! fig. 8. drainage system and till distribution in adventdalen (cf. fig. 1). the azimuth of the orientation and the total length of the tributaries in each direction were measured as defined by lines joining the nodes and head of stream segments after the method of morisawa (1964) and jarvis (1976) (fig. 10b). two distinct directions, northeast on the right bank of the valley and east-southeast on the left bank, oblique to the principal slopes of the valley, are indicated on fig. 1oa. generally, the drainage patterns are influenced by both geological struc ture and lithology. in particular the parallel or preferred orientation of the stream courses is usually influenced by geological structure. the structural geological data of this area collected along the skolten anticline and the duplex structure along adventelva (harem0 et al. 1990) show that the orientation of the dominant structure is "w-sse. according to these data, no relation between bedrock structure and the channel directions is apparent. except for the distinct moraines in front of the glaciers, the till and other superficial deposits over bedrock in this area are generally only a few metres or so thick. the till and sandstone erratics are distributed on interfluves between the tribu tary channels and on the terraces of the trough at definite levels (fig. 8). the drainage pattern and the distribution of the till in adventdalen (fig. 8) are interpreted as evidence showing that the glacial marginal channels and ice-cored moraines remain as relict landforms. the parallel-mnning tributaries and interfluves should be developed in the same manner as shown in fig. 7; the till on the interfluves was originally deposited on the ice cored moraine and the channels were formed as marginal channels. relationship between the landslides and the channels the vertical distribution of the landslide blocks, ice marginal channels and till are shown in fig. 9. in the main valley, the landslide blocks are 148 t. sawagaki & t. koaze legend festningen sandstone upper block group lower block group till ~x bedrock $. channel ‘* inferred dump surface ~ ~~ ~~ fig. 9. topographic profiles of adventdalen. locations of the profiles are indicated in fig. 8. situated at higher altitudes and do not reach the valley bottom. the channels, however, are mainly distributed on the lower part of the valley slopes or on the valley bottom. it is therefore difficult to find a direct connection between the two in the main valley. however, at the confluent point of helvetiadalen, on the southeast of helvetiafjellet (fig. l), a landslide block has come into contact with a channel and its lateral ridge (figs. 11 and 12). the ridge and the block are connected. the ridge continues to the southwest, though it is partly interrupted by the alluvial fan flowing down from above. some erratics and till were deposited on the ridge, and a few erratics can be seen on the landslide block. an alluvial fan spreads out at the place where helvetiadalen joins with adventdalen. at the fan top, in a river section of helvetiadalen, a well-layered section of flat-lying and alternating beds of fine sand and coarse gravel is exposed. the section appears to fig. 10. orientational data of the tributaries of the adventelva. the measurement was applied to the inner square in fig. 8. a. total length and orientation of the tributaries in adventdalen. b. angles were defined by joining ends of stream segments or links. have a gradational contact with a diamicton which includes striated boulders within a fine sand and clay matrix. these features are believed to demonstrate that the ridge and the channel were formed before the landslides and relict ice margin landforms 149 landslide because the slope instability was in creased by undercutting in the channel. discussion as previously stated, ice marginal channels and landslides intercepted by the former glacier ice are well developed in the adventdalen area. the jurassic argillaceous rocks dominating this area are weak and susceptible to weathering and erosion. the soft shale exposed extensively on the lower slopes and valley is subject to erosion and transport by glacial meltwater. thus, this rock type is unlikely to form distinct moraine ridges. although moraine ridges were once formed, because they were high in ice content, they subsequently decreased drastically in size. on the other hand, erosional landforms incised into the shale layer are likely to remain intact. it also seems likely that the angle of the slope at the interface between rock and ice is critical. flint (1971) stated that an ice-margin stream should easily be able to cut through the ice to the base of the slope in the case of a nearly vertical interface. with a flat-lying interface, as on a bedrock spur, a similar stream would more likely incise its channel into the bedrock. in the case of jansson dalen, the slope on the southern side of the valley is steeper than that on the northern side. ice margin channels develop on the northern slope but not on the southern side (fig. 8). regarding other areas where ice margin channels are absent, such fig. 11. landslide block and ridge distribution at the mouth of helvetiadalen. 150 t . sawagaki & t. koaze fig. 12. schematic sketch of the landforms and surface material development at the mouth of helvetiadalen. fig. 13. inferred position of the former ice margin in the midde part of adventdalen (cf. fig. 1). each ice margin inferred is identified by numbers of i, i1 ......, viii and ix. arrows in the figure are described in the text. as reindalen or the lower reaches of adventdalen, as the present ice front features show, channels both sides of the valley could be steep enough to are formed at the edge of the thin ice which is prevent meltwater streams from incising into the thought to be receding. even a small advance or a bedrock, which is made up of horizontally bedded short stagnation of the ice during the course of sandstones. deglaciation could be enough to form the landslides and relict ice margin landforms 151 rn a.s.1. fig. 14. inferred profile of the former ice surface along adventdalen. the recon struction of ice surfaces i and i1 is based on the altitude of the base of the upper and the lower landslide blocks. channels. on this assumption, these landforms indicate former positions of the glacier margin in the intervals of stagnation or at small re-advances. former position of the ice margin the former position of the ice margin and the former ice surface profile have been reconstructed in figs. 13 and 14, respectively, under the assumption that the till on the interfluves was originally deposited on the ice-cored moraine and that the channels were formed as marginal channels. the altitudes of the bases of the upper and lower landslide blocks are utilised for the reconstruction of ice surfaces i and 11. although absolute ages for the various ice margin positions are not available, the correlative recessional sequences of the glaciers are traceable. the main glacier retreat can be traced as i, 11,111, iv, v, vi, vii, viii and ix in figs. 13 and 14. retreat of the tributary glacier in helvetiadalen is denoted by i, 11, and iv. as for the janssondalen, positions 11, i11 and iv are inferred. as for stages i and 11, the former position of the ice front is uncertain. however, the ice of stage-i could have terminated in isfjorden to form the terminal moraines reported by ohta (1982), assuming that the ice surface corresponds to the last glacial maximum in this area. on the right bank of the valley, some of relatively large tributaries other than the river in helvetiadalen flow into the main river. a cirque has been formed at the upper end of each valley. a small glacier, arnicabreen, presently occupies the head of arnicadalen. taking these present-day features into consideration, these tributary valleys were probably filled with ice, and the glaciers likely joined dr~nbreen at the time of glaciation (arrows, fig. 13). the reconstructed positions of former ice margins suggest that some intervals of stagnation or small re-advances occurred during the course of deglaciation. however, it has been stated that the ice in spitsbergen dissipated rapidly in the warming climate of the early holocene age (feyling-hanssen 1955, 1965; forman 1989; mangerud et al. 1992), and there is widespread evidences for this throughout the arctic. in present day spitsbergen, surges are frequent phenomena and a common form of glacier advance (e.g. liest01 1969; schytt 1969; drewry & liest01 1985; dowdeswell 1986a,b; hagen 1987; dow deswell et al. 1991). glacial surge is thus most likely to have caused the stagnation and re advances during the course of deglaciation. conclusions fourteen landslide blocks are recognised on the southern slope of arctowskifjellet; they are divided into two groups based on the altitudes of the base of the blocks. the two levels of the landslide blocks seem to be related to the former ice surface levels, assuming that landslide blocks were intercepted by the glacier ice. the geo morphic changes produced by glacial erosion and glacial retreat are the causes of the landslides. these landslides are classified as belonging to the rotational bedrock slumps. the present-day ice marginal landforms, the development of drainage patterns and the dis tribution of till in adventdalen may reflect former ice marginal positions. the crumbly and erosive nature of the soft jurassic shale aided in channel incision. former positions of the glacier tongues were reconstructed on the basis of the relict ice marginal landforms. the landforms suggest that 152 t. sawagaki & t. koaze several episodes of stagnation or small re-advance phases occurred during the course of deglaciation. since few exact dating methods were used in this study, the deglaciation history in adventdalen remains difficult to date. acknowledgements. -we would like to thank y. ono, graduate school of environmental earth science, hokkaido university, for many helpful suggestions, advice and encouragement during the course of this work. we also thank k. moriwaki, national institute of polar research, japan, for permission and instruction in using the analytical photogrammetric system of that institute. for assistance in the field work, sincere thanks are extended to members of the japanese svalbard expedition in 1990: k. hirakawa, hokkaido university, n. matsuoka, tsukuba university, and s. sawaguchi, meiji university. we express our gratitude to y. ohta, 0. salvigsen, t. siggerud and other staff of norsk polarinstitutt for their logistical support for the expedition, and for their valuable help in preparing the manuscript. references boulton, g. s. 1979: glacial history of the spitsbergen archipelago and the problem of barents shelf ice sheet. boreas 8 , 31-57. dowdeswell, j. a. 1986a: drainage-basin characteristics of nordaustlandet ice caps, svalbard. j . glaciol. 32, 31-38. dowdeswell, j. a. 1986b: remote sensing of ice cap outlet glacier fluctuations on nordaustlandet, svalbard. polar res. . 4 n. s., 25-32. dowdeswell, j. a., hamilton, g. s. & hagen, j. 0. 1991: the duration of the active phase on surge-type glaciers: contrasts between svalbard and other regions. j. glaciol. 3 7 , 3 8 w o . drewry, d. j. & liestel, 0. 1985: glaciological investigations of surging ice caps in nordaustlandet, svalbard. polar rec. 22,359-378. feyling-hansen, r. w. 1955: stratigraphy of the marine late pleistocene of billefjorden, vestspitsbergen, norsk polar inst. skr. 107, 187. feyling-hansen, r. w. 1965: shoreline displacement in central vestspitsbergen and a marine section from the holocene of talavera on barentsoya in spitsbergen. norsk polarinst. medd. 93, 1-34. flint, r. f. 1971: drainage; eolian features. in: glacial and quaternary geology, new york, john wiley & sons ltd., forman, s. l. 1989 late weichselian glaciation and deglacia tion of forlandsundet area, western spitsbergen, svalbard. boreas 18, 51-60. hagen, j. 0. 1987: glacier surge at usherbreen, svalbard. polar res. 5 n. s., 239-252. haremo, p., anderson, a,, dypvik, h., nagy, j., elverhgi, a,, eikeland, t. & johansen, h. 1990 structural development along the billefjorden fault zone in the area between kjellstromdalen and adventdalen/sassendalen, central spitsbergen. polar res. 8 n. s., 195-216. jarvis, r. s. 1976: stream orientation structures in drainage networks. j . geol. 84, 563-582. 227-226 liestel, 0. 1969: glacier surges in west spitsbergen. can. j . earth. sci. 6, 895-897. liestel, 0. 1975: pingos, strings, and permafrost in spitsbergen. norsk polarinst. arhok 1975, 7-29. major, h. & nagy, j. 1972: geology of the adventdalen map area. norsk polarinst. skr. 138. mangerud, j. & svendsen, j. i. 1990: deglaciation chronology inferred from marine sediments in a proglacial lake basin, western spitsbergen, svalbard. boreas 19, 249-272. mangerud, j., bolstad, m., elgersma, a, helliksen, d., landvik, j. y., lycke, a. k., lqnne, i., salvigsen, o., sandahl, t. & sejrup, h. p. 1987: the late weichselian glacial maximum in westem svalbard. polar res. 5 a s . , 275-278. mangerud, j., bolstad, m., elgersma, a, helliksen, d., landvik, j. y., u n n e , i., lycke, a. k., salvigsen, o., sandahl, t. & svendsen, j. 1. 1992: the last glacial maximum on spitshergen, svalbard. quat. res. 38, 1-31. miller, g. h., sejrup, h. p., lehman, s. j. & forman, s. l. 1989: glacial history and marine environmental change during the last interglacial-glacial cycle, westem spitsber gen, svalbard. boreas, 18, 273-296. morisawa, m. e. 1964: development of drainage systems on an upraised lake floor. am. j. sci. 262, 340-354. ohta, y. 1982 morpho-tectonic studies around svalbard and northernmost atlantic. embry, a. f. and balkwill, h. r. (eds.): arctic geology and geophysics. canad. soc. petrol. geol. mem. 8, 415-429. ono, y., matsuoka, n., sawaguchi, s., shimokawa, k., fukuda, m., takahashi, n., shiraiwa, t., hasegawa, h., yoshikawa, k. & muto, h. 1991: geomorphological results of the japanese expedition to svalbard, 1988-1989. mountain res. dev. i i , 259-269. parker, j. r. 1967: the jurassic and cretaceous sequence in spitsbergen. geol. mag. 104, 487-505. salvigsen, 0. 1979: the last deglaciation of svalbard. boreas 8 , 229-231. salvigsen, o., eligersma, a., hjort, c., lagerlund, e., liestel, 0. & svensson, n. 0. 1981: glacial history and shoreline displacement on erdmannflya and bohemanflya, spitsber gen, svalbard. polar res. 8 n. s., 261-273. shiraiwa, t., sawaguchi, s., hasegawa, h., sawagaki, t. & ono, y. 1991: timing of the little ice age glaciation in reindalen, western spitsbergen, reconstructed by lichenometry. proceedings of the international symposium on the little ice age climate, september, 1991. tokyo metropolitan univ., tokyo, japan. schytt, v. 1969 some comments on glacier surges in eastern svalbard. can j . earth sci. 6, 867473. svensson, h. 1988 ice-wedge casts and relict polygonal patterns in scandinavia. j . quat. sci. 3, 57-67. troitsky, l. s., punning, j. m., ht, g. & rajamae, r. 1979: pleistocene glaciation chronology of spitsbergen. boreas 8, 401-407. varnes, d. i. 1978: slope movements and types and processes. in: landrlides: analysis and control, transportation res. board, nat. ac. sci., washington spec. rep. 176, 11-33, (cited by hansen, m. j. 1984). werner, a. 1989: holocene glaciation and climatic change, spitsbergen, svalbard. ph. d. thesis, university of color ado. primary production in polar waters: relation to nutrient availability w. g . harrison and g . f. cota harrison, w. g. & cota. g. f. 1991: primary production in polar waters: relation to nutrient availability. pp. 87-104 in sakshaug, e., hopkins. c. c. e. & oritsland. n. a . (eds.): proceedings of the pro mare symposium on polar marine ecology. trondheim. 12-16 may 1990. polar research l o ( 1 ) . temperature, light and dissolved nutrients are considered the “master” abiotic properties controlling primary production in the ocean. each of these properties, in turn, is influenced by water column stahility and vertical mixing. sustained research over the past several decades has endeavored to ascertain which of these properties is most important in regulating phytoplankton growth. i n no region has this research effort been more evident than at high latitudes. for both polar regions, extremes in each of these properties is the rule in surface waters where phytoplankton grow: the lowest ocean temperatures, the greatest seasonal excursion in incident solar radiation, and the highest dissolved nutrient concentrations. based largely on indirect evidence, early researchers speculated that polar primary production was high relative to production at lower latitudes. this was commonly attributed to the abundant surface “macronutrients” (no3, po4, h4sioj) since physiological adaptations to the suboptimum temperatures and light were thought t o characterise these high latitude populations. intensification of polar research since the late 1960’s has in many respects modified this view. current perspectives are that important differences exist between the arctic and antarctic with regard to the availability and role nutrients play in regulating primary production. in general much less emphasis is now placed on the significance of the macronutrients in the antarctic although there is speculation and some evidence that “micronutrients” (fe) may be important. macronutrient availability appears to play a more important. though secondary. role in the arctic. that of sustaining rather than initiating phytoplankton growth. this paper reviews early. contemporary, and present research addressing the question. “what role does nutrient availability play in the distribution and magnitude of primary production in arctic and antarctic waters?” emphasis is placed on new research on under-ice communities as well as on the historically studied pelagic communities. w . g . harrison, biological oceanography division, department of fisheries and oceans. bedford institute of oceanography, p.o. box 1006, dartmouth. nova scotia, canada b2y 4a2; g. f. cora. graduate program in ecology, university of tennessee, knoxville. tennessee 379%, usa. introduction over the past two decades, oceanographic research in polar oceans has made considerable progress in identifying the environmental (abiotic and biotic) properties which regulate the biomass and productivity of high-latitude phytoplankton (fogg 1977; holm-hansen et al. 1977; nemoto & harrison 1981; sakshaug & holm-hansen 1984; priddle et al. 1986; jacques 1989; sakshaug 1989; smith & sakshaug 1990). among the factors com monly considered are 1) temperature, 2) light, both solar variations and how it is influenced by the presence of sea-ice, 3) nutrients, 4) turbu lence, or conversely, water column stability, and 5) food web interactions, e.g., grazing losses (el sayed 1984). currently, it is believed that the environmental factors which exert the greatest control on polar phytoplankton growth are the low and relatively invariant temperatures, the presence (or absence) of sea ice and the extreme seasonal variations in the high-latitude light regimes (smith & sakshaug 1990). in general, therefore, turbulence/stability, food web inter actions and nutrient availability (the latter deter mined by these physical and biological processes, i.e. “new” and “regenerated” nutrients, dugdale & goering 1967) may be considered to exert secondary effects on primary production or play a more confined role regionally or temporally. this paper deals with the specific role nutrients play in limiting, or more correctly controlling (thingstad & sakshaug 1990) primary production in both the pelagic and sea-ice phytoplankton communities of the arctic and antarctic. the emphasis is on the essential macro elements n , p, and si, although we recognise that, strictly speaking, the term “nutrients” has a much 88 w . g. harrison & g. f. cora broader connotation which encompasses the trace elements essential for plant growth ( e . g . fe) as well as the non-essential elements (holm-hansen 1985). under natural conditions. unequivocal proof of "nutrient limitation" of primary production can infrequently, if not rarely, be established. limi tation is generally deduced from indirect evidence such as 1) the presence or absence of essential nutrients in the upper water column (usually the mixed layer), 2 ) covariance (direct or inverse) of nutrients with phytoplankton biomass and/or productivity, 3 ) nutrient bioassays, 4 ) cellular chemical composition. or 5 ) relative nutrient util isation rates. these indirect indices will form the basis for the discussion developed in this paper. there is an extensive amount of current litera ture dealing with this and allied topics. and our review merely touches on some of the highlights. why consider nutrients? in the absence of any influence of nutrients, the general features of oceanic primary production average sea-surface temperature 1 80 60 40 2 0 0 20 40 60 80 clear sky lrradiance at surface lo00 i 800 6 ? 600 400 5 9 0 200 .. 0 . . , . , . i . , . , . i . , . 80 5 3 40 20 0 20 40 60 80 s latilude (deg) n fig. i . latitudinal \ m a t i o n s in averagc sea surfacc tcmpcrature (pickard 1964) and incident solar radrdtion (ivanoff 1975. see also campbell & aarup 19x9 for par variations). lowcr panel also shows annual range hased on monthly means. geosecs data i p a c i f i c i 7 0 6 0 5 0 40 30 20 10 0 1 0 20 30 40 50 60 70 4 0 30 t e e e 0 20 10 0 7 0 6 0 5 0 4 0 30 2 0 1 0 0 10 20 30 40 50 60 70 s n latitude (deg) fig. 2. latitudinal variations in no3 and h,sio, concentrations in surface waters of the atlantic and pacific oceans. geosecs data (bainbridgc 1976a. b ) . and phytoplankton biomass would be expected to follow the global ocean patterns in available light and temperature (fig. 1) with the highest levels at low latitudes. it is clear, however, that t h e major patterns in the distribution of biological activity show lowest levels at low latitudes. indeed, global plankton distributions a r e more closely correlated with the distributions of elev ated sea surface nutrients (reid 1962) which increase with latitude (fig. 2). this apparent link between nutrients and biology led sverdrup (1955) to construct the first global m a p of ocean productivity (fig. 3 ) based o n the tenet that, .'. . . productivity depends on the rate at which plant nutrients of the surface layers a r e renewed and that the renewal takes place by physical pro cesses. such as vertical convection, upwelling and turbulent diffusion. . .". this picture of the global distribution of ocean productivity and biomass is remarkably similar to o u r current views based on cumulative field measurements (berger 1989) and ocean color satellite images (lewis 1989), with one notable exception; sverdrup's m a p depicts polar primary productivity in the highest category, for example on the same scale as that primary production in polar waters 89 fig. 3. schematic representation of global productivity (relative) based on variations in nutrient “rcnewal” to surface waters by physical mixing processes (redrawn from sverdrup 1955) of coastal upwelling systems. we now know that this is clearly not the case, particularly for the antarctic (holm-hansen et al. 1977; subba rao & platt 1984). the prevailing contemporary view is that factors other than nutrient “replenishment” are comparable or of greater importance in setting the limits on primary production at high latitudes. the pelagic production zone multidisciplinary investigations of the ecology of polar marine communities (distribution, pro ductivity and their relationship to the environ ment) did not become an important component of ocean research until the late 1960s and early 1970s (llano 1978; el-sayed 1988). studies have increased markedly in recent years: in the arctic, the probes and ishtar programs (bering chukchi seas), the mizex and cearex programs (east greenland sea) and pro mare (barents sea); and i n the antarctic, the a m e r i e z (wedd ell-scotia seas) and racer programs. despite the relatively late start in multidisciplinary polar oceanography, most of the major arctic and ant arctic water masses (fig. 4) have been studied sufficiently to permit some generalisations about phytoplankton and the role nutrients play in its distribution and production. antarctic open waters persistently high nutrient concentrations. especially nitrate (no3), phosphate (po,), and silicic acid (h4si04), in antarctic surface waters are distinctive characteristics of the southern ocean (fig. 2). indeed, nutrient concentrations south of the polar front (-50”s) are among the highest in any surface waters i n the world; no3, h4si04, and po, levels in summer can exceed 20 mmol m-3, 50 mmol m-3, and 2 mmol m-3, respectively (priddle et al. 1986; jones et al. 1990). this is due largely to the massive-scale upwelling of deep north atlantic waters at the antarctic divergence. from the standpoint of phytoplankton ecology, this system has been described as a “giant chemostat” (holm-hansen 1985) which provides an abundant, spatially uni form and continuous supply of nutrients for pri mary production. though nutrient concentrations decrease in response to the phytoplankton growth cycle, they are rarely consumed to depletion, even during massive blooms (el-sayed 1984). more over, classical nutrient enrichment assays have failed to demonstrate an increase in phyto plankton biomass or stimulation of production by the addition of the major or minor (trace) nutrients (jacques 1983; hayes et al. 1984). elemental ratios of the particulate matter (c/ n, n/p, c/p) deviate little from the expected redfield ratios (smith & sakshaug 1990) which also argues against any significant n or p defi ciencies. with respect to nitrogen limitation, the case is further weakened when one considers that, in addition to no3, reduced forms (nh,, urea) are available and usually preferentially utilised; 90 w . g. harrison & g. f . cota atlanth ocean . . . . ~ fig 4 major present and past sites of ecological sludies in polar oceans up to 5 0 7 ~ or more of the phytoplankton nitrogen demand is met by this "regenerated" nitrogen produced locally as plankton metabolic wastes (smith & nelson 1990. and references cited therein). specific instances have been reported, however, where nutrient limitation was suspected. holm-hansen et al. (1989), for example, observed depletion of no3 and po4 in surface waters in the vicinity of palmer station during an intense phytoplankton bloom: chloro phyll a (chl) = 4-30 mg m-3. ancillary measurements of cellular biochemical properties also revealed abnormally high chl/adenosine triphosphate (atp) and particulate organic car bon (poc)/atp ratios, indicative of nutrient limited populations. exhaustion of surface no3 and po4 have also been reported in some ice primary production in polar waters 91 edge communities in the ross sea (nelson & smith 1986; see next section). other findings have suggested that h4si04 may limit (or have the potential to limit) phytoplankton growth. based on an analysis of n03-h4si04 and p04-h4si04 relationships in the world’s oceans using the extensive nodc nutrient database, zentara & kamykowski (1977) and kamykowski & zentara (1985,1989) have shown the potential for h4si04 depletion in surface waters in the southern ocean, particularly in waters south of the sub tropical convergence and north of the antarctic divergence. holm-hansen et al. (1977) also drew attention to this region, noting that h4si04 con centrations decreased northward from the diver gence much more rapidly than did no3 and po,; this is clearly seen in the geosecs data in fig. 2 (see also le jehan & treguer 1985). differential loss of r the highly silicified phytoplankton (primarily diatoms) by sinking and low si-dis solution rates (relative to regeneration of n and p) as a result of the prevailing low seawater tem peratures has been the favored explanation (nel son & gordon 1982; treguer et al. 1989). biochemical and physiological characteristics of antarctic diatoms also point t o the potential for si-limitation. silicification appears much greater in antarctic diatoms than in more temperate forms; often si/c ratios are significantly elevated (see also section below) relative to normal ratios (brzezinski 1985), suggesting an unusually high si-demand for growth (smith & sakshaug 1990). studies of si uptake kinetics have also revealed very low substrate affinities in some strains of antarctic diatoms; k, values ranging from 12 90 mmol m-3 have been documented (jacques 1983; sommer 1986), as compared with normal values in the range of 1-5mmol m-3. elevated k, values imply the potential for si-limitation even at the high ambient h4si04 levels charac teristic of the southern ocean. a discussion of the nutrient effects on pro ductivity of antarctic open waters would not be complete without commenting on several recent papers dealing with the possibility of “trace” nutrient (specifically, fe) limitation in the southern ocean (martin & fitzwater 1988; mar tin & gordon 1988; martin 1990; martin et al. 1990b). trace metal enrichment experiments have been done previously in the antarctic (jacques 1983; hayes et al. 1984) but with nega tive results. metal-free “clean” techniques were not used, and the findings have consequently been considered suspect. using “clean” techniques, martin and colleagues showed that despite the presence of high ambient concentrations of macro-nutrients, phytoplankton growth in the subarctic pacific was stimulated only after the addition of nmolar amounts of fe. this apparent fe-deficiency was attributed to low inputs from the atmosphere (the primary source of fe in the open ocean) in the region. they further specu lated that the “antarctic paradox” (low pro ductivity despite high nutrients) may be explained using the same argument. interestingly enough, hart (1934) was one of the first to suggest fe deficiency as a controlling fact of antarctic pro ductivity. martin et al. (1990b) subsequently showed that high productivity in antarctic coastal waters was associated with high ambient fe con centrations, whereas low productivity zones were extremely low in fe offshore. martin (1990) also noted an apparent link between fe availability and glacial/interglacial coz levels based on analy sis of antarctic ice cores. martin’s conclusions, however, have not been universally accepted because of questions arising from details of his methodology (banse 1990, 1991; see also martin et al. 1990a). buma et al. (1990) have carried out contaminant-free enrichments experiments in the weddell and scotia seas, showing fe stimulation of chlorophyll a synthesis and nutrient assimi lation, but growth in their control (unenriched) treatments also exceeded levels normally observed. they thus concluded that fe was likely only one of several growth-limiting factors. sak shaug & holm-hansen (1984) argue that observed variations in antarctic productivity and biomass accumulation can be sufficiently explained by mixing and its effects on the phy toplankton light environment. antarctic marginal ice zone the view of the antarctic as an “oligotrophic” ocean (jacques 1989) has been modified by recent findings that a substantial portion of the annual productivity is associated with the southward retreating ice edge during the austral spring-sum mer (jennings et al. 1984; smith & nelson 1986). according to current estimates, the marginal ice zone accounts for about 40% of the total antarctic primary production (smith & nelson 1986). bio mass and productivity associated with the ice edge are among the highest recorded for the southern ocean (el-sayed 1971) and are typically higher than levels found in surrounding waters (smith 92 w . g. harrisori kc g. f. cotm & nelson 1985); i t therefore tollows that the potential for nutrient limitation should be greatest there. studies to d a t e , however, d o not generally bear this out although nutrient levels are reduced to a greater extent than in surrounding waters (el-sayed & taguchi 1981; nelson & smith 1986: nelson et al. 1989). t h e o n e exception is the study of nelson & smith (1986) where n o 3 and po4 were reduced to levels below analytical detection in surface waters a t two stations in the ross sea. these investigators have also noted exceptionally high h,sio, demand and si/c com positional ratios ( 6 8 x normal) of the ice edge diatoms in the ross (nelson & smith 1986) and weddell seas. even in the late summer when the ice edge is stationary (nelson et al. 1989). this fact along with observed low substrate affinities described previously (jacques 1983; sommer 1986) may potentially lead t o si-limitation. even if concentrations a r e not reduced t o extremely low levels. si-limitation. however, has not been conclusively demonstrated in the field yet. over all. the link between nutrient availability and primary production in the antarctic marginal ice zone seems weak at present. in summary, despite isolated examples of nutri ent exhaustion in intense bloom conditions in shallow waters or near the ice edge and evidence of atypically high nutrient demand (specifically, h4si04) by some phytoplankton species, it is presently felt that the distribution and production patterns of southern ocean phytoplankton bear little relationship to the distribution of the major nutrients. t h e converse apparently is true o n the small to meso-scale, e . g . biological processes apparently have a major influence on the dis tribution of hisio, (relative to that of n o 3 and po4) in waters flowing northward from the ant arctic divergence ( j o n e s et al. 1990). o t h e r environmental or biological factors are currently felt to be more important in the initiation of southern ocean phytoplankton production and growth, with nutrients playing a secondary role (i.e. sustaining growth) at best. the exact role of “trace” nutrients is an intriguing question; however. their status as major controlling factors is as yet unresolved. arctic o p e n waters in marked contrast to the antarctic, nutrient concentrations in arctic/subarctic surface waters are considerably lower (see fig. 2 ) and commonly reach exhaustion in summer (codispoti & rich ards 1968: hameedi 1978; alexander & niebauer 1981: harrison et al. 1982; rey & loeng 1985; smith et a [ . 1985; whitledge e t al. 1986; mac donald & wong 1987; spies e t al. 1988). in fact, sakshaug & holm-hansen (1984) have made the observation that maxiniirm arctic concentrations are typically lower than minimum antarctic con centrations. of t h e three macronutrients con sidered, po, is almost universally present in excess in arctic waters (but see macdonald et al. 1987). even during summer when surface con centrations are usually at their lowest and the potential for nutrient limitation therefore gen erally focuses o n n o 3 or h 4 s i 0 4 . a n inspection of kamykowski & zentara’s (1985) analysis of n 0 3 h 4 s i o j relationships in the world’s oceans revealed relatively few data sets for arctic waters which permit a n assessment of the prevalence of, or potential for, n o 3 versus hjsiol exhaustion in surface waters. t h e available results suggest excess h3sioj at no, depletion in t h e chukchi and western beaufort seas and either n o 3 o r h 4 s i 0 4 depletion in the northern bering sea and the eastern greenland/norwegian seas. a more selective but less comprehensive analysis of no, h 4 s i 0 , relationships for representative data sets in summer months suggests that the potential for no, limitation may be more common (fig. 5 ) , even in the arctic basin (english 1961). t h e r e are notable exceptions, however, t o this pattern in other arctic regions. for example, rey & skjoldal(l987) observed a regular and apparently extensive d e e p h 4 s i 0 4 depletion. extending well beyond the depth of the nitracline, in the barents sea during sedimentation of the spring diatom bloom. they suggested that subsequent diatom growth during summer could be retarded as a result since the positioning of the h4siol gradient below that of the no3 and po4 gradients would mean relatively less hjsiol available to the base of the photic zone when mixing occurred. in a long term study of no3-h4sio4 relationships in waters off iceland, stefansson & olafsson (1990) described years where h,sio, was in excess as “anomalous”, occurring only when the spring bloom was dominated by non-diatom algae such as the prymnesiophyte, phaeocysris pouchetii. codispoti et al. (1990) noted a similar residual of h 4 s i 0 , in surface waters of t h e greenland sea coincident with phaeocysris blooms. in any event, surface nutrient exhaustion in summer and con comitant reduction in phytoplankton productivity primary production in polar waters 93 ? e e" e y ? e canadian ice island nansen basin 40 8 30 6 204 2 y = 0.31 + 2.12 x y 1.34 + 0.31 x 0 7 1 i 1 0 5 1 0 1 5 2 0 0 5 1 0 1 5 chukchl sea 501 e e y 0 5 10 15 eastern canadian arctic a ? e 40 30 y 3.14 + 1.87 x 0 5 1 0 1 5 2 0 n i t r a t e (mmol m-3) i g y drift station alpha 0 2 4 6 8 10 1 2 labrador sea 2o 1 15 1 0 5 1 0 15 20 nitrate (mmol m.3) fig. 5. n0,-hisi04 relationships for selected sites in the arctic. line represents least-squares linear regression f i t . data sources: canadian ice island b. t. hargravc (unpubl. data). nansen basin e. p. jones (unpubl. data), chukchi s e a hameedi (1978). eastern arcticirwin et al. (1978a. 1982. 1983. 1984. 1985. 1987. 1988). labrador seairwin et al. (1978b. 1 9 7 8 ~ . 1986a. 1986b. 1988. 1989). 94 w . g. harrison & g. f. cota and biomass are widespread features of the arctic. establishing a direct link between nutrients and phytoplankton variations in the arctic summer is not always straightforward. extensive studies over several years in the eastern arctic (labrador sea to northern baffin bay) have failed to dem onstrate any statistical relationship between phy toplankton biomass or productivity indices and ambient nutrient concentrations (harrison & platt 1986). multivariate analysis (step-wise regression) of an updated and more extensive (627 observations) data set of photosynthesis irradiance parameters and environmental factors (fig. 6, table 1) confirm harrison & platt's earlier conclusions; only temperature and light contri buted significantly t o the variance in p c , the maximum photosynthetic rate at light saturation, while biomass contributed (but only marginally) to the variance in d, the photosynthetic efficiency parameter (table 2). a similar analytical t a b k 1 . range and mean values for chlorophyll a (chl. mg m ' ) . photosynthesis-irradiance parameters (p: = mgc mgchl-' h ' . m a = mgc mgchl ' h ' (pmol m-: s ' ) ' , and selected environmental properties of the upper water col umn i n the labrador sea and eastern canadian arctic (see fig. 6). sample depth = metres. temperature ( t ) = "c, no3 concentration = mmol m-'. no. obs minimum maximum mean p i 674 0.11 12.84 2.04 0 8 673 0.001 0. i88 0.018 chl 672 0.03 25.27 2.44 depth 674 0 80 18 t 653 -1.8 11.5 1.9 no, conc. 650 0.00 16.55 2.17 approach was taken in assessing nutrient effects on water-column integrated productivity of a sub set of the above d a t a (29 stations) from baffin bay and adjoining waters (table 3). in this analysis, neither nutrient concentrations n o r nutrient util fig. 6. station locations in the eastcrn canadian arctic (labrador sea. baffin bay and adjoining waters) where photosynthcsis irradianec ( p i ) mcasurements have been made (see also table i ) . primary production in polar waters 95 table 2 . stepwise regression analysis of photosynthesis-irradiance parameters and selected environmental factors from field work covering summer periods from 1977-1984 and including regions from ca. wn-79"n latitude (data summarised in table 1 ) . adjusted r2 rms residual f a . dependent variable: p z independent variables included: temperature 0.252 1.33x 164.52 sample depth 0.274 1.318 20.06 variables excluded: no, conc. 2.49 chlorophyll a 1.42 independent variables included: chlorophyll a 1.61 b. dependent variable: d' variables excluded: sample depth 3.14 temperature 2.51 no1 conc. 0.37 0.01 i 0.069 isation rates contributed to the observed variation in primary productivity; incident radiation and phytoplankton biomass were the only significant co-variates (table 4). studies in the bering sea, on the other hand, have clearly established the link between no3 and productivity/biomass levels in late spring and summer, e.g. in associ ation with shelf-break mixing (iverson et al. 1979), wind mixing events (sambrotto et al. 1986), and ice edge upwelling (alexander & nie bauer 1981). the availability of no3 appears to be a major determinant in the spatial and temporal table 3 . range and mean values for chlorophyll a (chl, mg m-'). carbon productivity (pp. mgc m 2 d ' ) , nitrogen productivity (pno, & pnh,, mmol m-* d-i) and selected environmental properties of the upper water column in the eastern canadian arctic during summer 1978 & 1980 (harrison e l al. 1982, 1985). average daily incident radiation ( i j = mol m 2 h l . temperature (1) = "c. photic dcpth ( z , ) and mixcd layer depth (2,) = metres. n o , & nh, concentration (mmol m-2). and f-ratio = p n 0 3 / ( p n 0 , + pnhi). no. obs minimum maximum mean chl pp pnoi pnh, f-ratio 1,) 2, 2, no, conc. nh4 conc. t 29 12.8 121.7 49.2 29 105 1076 298 29 0.34 8.00 2.22 29 0.19 3.20 1.49 29 0.19 0.88 0.54 29 0.47 3.00 1.51 27 -1.0 7.8 1 . 1 29 24 54 34 29 0 22 13 29 0.7 227.1 59.8 29 0.7 16.5 4.9 distribution of phytoplankton in that region (mcroy et al. 1972; whitledge et al. 1986; walsh et al. 1989; hansel1 et al. 1989). further south in the gulf of alaska, surface no3 concentrations rarely reach undetectable levels even in summer (anderson et al. 1969). martin & fitzwater (1988) attribute this and the relatively low productivity of the region to fe-limitation, although sup pression of no3 uptake by nh4 has also been suggested (wheeler & kokkinakis 1990). in the eastern arctic, rey et al. (1987) established a clear relationship among chlorophyll a biomass, no3 utilisation rates, and water column stability in temporal studies in the barents sea over a several year period. despite the common absence of no3 from summer surface waters, reduced-n forms (nh4, urea), which are often not routinely measured, constitute a significant fraction of the nitrogen available for phytoplankton growth in the arctic and may mitigate to some extent the potential limiting effects of no3 depletion (harrison et al. 1982, 1985); uptake patterns of the reduced-n compounds to date have provided no evidence that the summer phytoplankton populations are severely n-limited (harrison et al. 1982; harrison 1983; kristiansen & lund 1989). this may help to explain the lack of correlation between phy toplankton indices and nutrients in the eastern arctic. it seems clear, in any event, that other environmental factors may be more important on the time/space scales characterising these data (harrison et al. 1982; harrison & platt 1986). regenerated-n forms constitute a surprisingly 96 w . g. harrison & g. f . cora table 4 . stepwise regression analysis of water-column integrated primar) productivity and selected environmental factors from summer field work in bafhn bay and a d ~ o i n i n g waters. e a t e r n canadian arctic. iy7h and i980 (data summariscd in table 3 ) . adjusted r: rms residual f a . dependent variable: chlorophyll ( i ( c h l i independent variables included: incident radiation 0.299 25 90 12.07 variables excluded: f-ratio i .70 temperature 0.43 n-uptake 0.37 chlorophyll a 0.395 159.67 43.49 inorganic-n conc 0.49 b. dependent lariahie: primary productivity (pp) independent variables included: incident radiation 0.614 127 5 4 15.19 f-ratio 1.22 temperature 0.98 n-uptake 0.65 inorganic-n conc 0.34 variables excluded: inorganic-n = n o i + nh,. n-uptake = n o x + nh, uptake. f-ratio = n o , u p t a k e / ( n o , + nh,) uptake large portion of the nitrogen productivity in both the arctic (harrison et al. 1982; muller-karger & alexander 1987; kristiansen & lund 1989; smith & kattner 1989) and the antarctic (slawyk 1979; olson 1980, gilbert et al. 1982; ronner et al. 1983; collos & slawyk 1986; koike et al. 1986; smith & nelson 1990). which suggests that biotic controls on nutrient availability need more serious consideration than i n the past. arctic marginal ice zone biological activity in the marginal ice zones is as important to the annual primary production cycle in the arctic as it is in the antarctic (smith 1987). detailed calculations for the bering sea. for example. show that the ice-edge communities account for 40-508 of the total regional pro duction (mcroy & goering 1976; v . alexander, cited in smith 1987). although the effects of melting ice on vertical stability is considered the major factor i n the rnirrarion of the ice edge blooms, its consequences in the arctic are mark edly different from those in the antarctic. meltwater stability provides a more suitable light environment for phytoplankton growth but it also imposes a barrier to nutrient resupply once mixed layer reserves are depleted. in the antarctic. of course. this presents little problem since nutrient concentrations are usually well in excessof growth requirements. however. in the arctic, surface concentrations are much lower and are generally depleted early in the growing season, particularly in the marginal ice zone (alexander & niebauer 1981: 1989; rey & loeng 1985; smith et al. 1985; spies et al. 1988). in the arctic, therefore, nutri ent availability (i.e. resupply) is a major factor in the maintenance of ice edge production. mixing processes such as ice edge upwelling and eddy formation are considered the principal resupply mechanisms in both the bering (alexander & niebauer 1981; muller-karger & alexander 1987) and east greenland (buckley et al 1979; smith et al. 1985; johannessen et al. 1987) seas. rey &i loeng (1985) found no evidence of upwell ing i n their studies of the ice edge production cycle i n the western barents sea but noted a seasonally progressive deepening of the phy toplankton biomass, tracking the nitracline and residing well below the pycnocline by late summer. post bloom production appeared to be supported principally by biotic nitrogen sources. i.e. "regenerated"-n (harrison et al. 1982. 1985; muller-karger & alexander 1987; kristiansen & lund 1989) as is the case in temperate waters. in summary, whereas nutrient availability may only rarely influence phytoplankton dynamics in the antarctic, some degree of nutrient limitation seems the rule i n arctic waters, especially in summer. the link between nutrients (no3 or h 4 s i 0 4 ) and phytoplankton biomass and pro ductivity has been clear in some studies, par prirnary production in polar wafers 91 tively low with little seasonal variability; evidence for in situ growth is limited to a slight nutrient depletion in ice (dieckmann e t al. 1990). bottom ice algae on land-fast ice, by contrast, have been studied intensively and the largest blooms occur during local spring when there is little competition for nutrients. benthic algae with summer growth maxima, on the other hand, a r e in direct com petition with phytoplankton for light and nutri ents. over large scales phytoplankton and ice algae dominate polar productivity because of their wider distributions. ice algal productivity appears to be most pro nounced under land-fast annual ice in regions with high nutrients and low snow cover. in providing a highly concentrated resource for grazers and augmenting phytoplankton production, they are important in prolonging the brief polar growth season. during their peak growth season, ice algae dominate local autotrophic activity ( h o m e r & schrader 1982). bottom ice algal assemblages are confined to the ice water interface because of low temperatures; this represents the t o p of the seasonal euphotic zone. photosynthetically active radiation incident o n bottom ice algae is usually 1-5% or less of surface irradiance, and when heavily colonised 80-90% is absorbed within the algal layer (welch & bergmann 1989). accumu lations of 10&300 mg c h l m-?, predominantly pennate diatoms, are common in productive regions (smith e t al. 1988; cota & sullivan 1990; welch & bergmann 1989). visible bands of pig ments are confined to a few cm. intense gradients of nutrients and light across this layer suggest that cells at the t o p receive elevated irradiances but may be nutrient-limited whereas the reverse occurs at the bottom of the layer, i.e. light-limited and nutrient replete (cota & horne 1989; cota et al. 1990; smith e t al. 1988,1990). in this regard, the ice algal layer may be largely analogous to phytoplankton in the water column but vertically compressed. nutrients available to ice algae come from three principal sources: ice desalination, biological regeneration in situ, and mixing of the adjacent water column (cota e t al. 1987). the largest pool of nutrients is the latter (fig. 7). most salts (70 80%) are excluded from sea ice during formation while ice growth, which persists over about half of the vernal bloom, promotes convective fluxes at the interface (reeburgh 1984). subsequent brine drainage is almost continuous, but most salts in sea ice are locked within the ice until the ticularly where physical mixing processes dominate (for example the marginal ice zone), but more difficult to establish in other studies where regenerative, “biotic”, processes appar ently dominate (for example the summer open waters condition of the eastern canadian arctic). in polar waters in general, it is clear that several environmental factors collectively determine the distribution and activity of phytoplankton, how ever, nutrient availability appears to rank high among these in the arctic. the under-ice production zone besides being vast, remote and inhospitable with planetary extremes in temperature, light and nutrients. polar oceans have a n annual fluctuation in ice cover of about 23 x lo6 km2, most of which is first-year ice. sea ice influences heat flux, ther mohaline structure of the upper ocean, air-sea interactions such as gas exchange and momentum transfer, albedo. the transmission of irradiance, and biological activity, especially primary pro ductivity. acute undersampling and bias in polar observations reflect the historical emphasis on ice-free areas during the summer navigable season. t h e proliferation of studies near ice edges and in ice-covered systems over the last decade or two has greatly improved our appreciation for the space/time variability of primary productivity. initially, primary productivity under seasonal or permanent ice cover was thought t o be neg ligible because of very low irradiance and tem perature (english 1961), but several groups of algae are capable of growing in ice-covered waters or o n sea ice. benthic algae, including micro phytes and macrophytes, phytoplankton, and ice algae, all have been found t o display net pro duction under certain ice-covered conditions ( h o m e r & schrader 1982; dunton 1985; dayton et al. 1986; rivkin et al. 1989). these algal groups have characteristic distributions and periods of maximum growth. t h e benthic algae a r e restric ted t o shallow regions (<2&50 m ) , and although most algae have summer growth maxima during open water periods, some macrophytes utilise stored carbon reserves and display winter growth peaks when nutrients are highest and competition lowest (dunton 1985). ice algae are associated with most types of sea ice, but particularly annual (first-year) ice. little is known about pack ice assemblages except that biomass levels are rela 98 w . g . harrison & g . f. cota 2 0 20 4 0 e i i l lu n 60 80 1 0 0 nitrate (mmol m 0 5 1 0 a i i i i i v - t i i i i i i i a 0 1 0 20 30 silicic a c i d (mmol m3, f i g . 7. schematic representation of no, and h&ioj distribution through ice and water column. late spring melt when concentrated brines exit from particular sites (50-200 brine channels mw2), maintaining their identity well below the interface. biomass accumulations indicate that large amounts of nitrogen and silicon are needed to account for minimal requirements of net popu lation growth. regenerative fluxes can supply only a small portion of algal demand, especially for silicon. however, nutrients in seawater are more than adequate to satisfy demand, but fluxes are episodic (cota et al. 1987; cota & sullivan 1990). productivity and maximum biomass accumu lation of bottom ice algae in some cases appear to be related t o nutrient availability. in southeastern hudson bay classical enrichment bioassays have shown that nitrogen limits ice algal biomass in estuarine waters (maestrini et al. 1986). moreover, welch et al. (1991) suggest that the maximum ice algal biomass is directly pro portional to mean water column no3 for 5 shallow (<150 m) sites in the canadian arctic. welch and co-workers also hypothesised that no3 con sumption by macrophytes in winter may reduce nearshore nitrogen concentrations in northwest ern hudson bay. they also found that depletion of h4si04 in barrow strait exceeded 275 mmol m-’ between april and june in the top 100 m of the water column well before any phytoplankton bloom (welch & begrnann 1989; see also cota et al. 1990). even in areas with relatively strong currents, steep and persistent nutrient gradients primary production in polar waters 99 relatively constant compared to planktonic systems. nutrients, on the other hand, may be depleted and resupplied episodically as in pelagic environments; in sea ice, nutrients must be avail able within, or delivered to, a narrow stratum. except in the lowest few centimetres, nutrient concentrations are low in sea ice and could sustain only a brief ice algal bloom if they were readily available. regenerative processes satisfy a por tion of the required nitrogen and phosphorus, but dissolution of biogenic silica appears to be too slow to provide much h4si04. if high standing stocks of ice algae are attained and have sufficient light to continue growing, then rates of external nutrient supply, particularly from the water column, may become limiting even in the most nutrient-rich polar waters. with near surface minima have been observed in "well mixed" surface layers beneath heavily colonised sea ice, confirming a strong source sink relationship (cota et al. 1987, 1990; cota & horne 1989). at sites in the arctic and subarctic, vertical nutrient fluxes appear to be linked closely to tidal forcing, and fluctuations in supply can influence ice algal photosynthetic response and biomass (gosselin et al. 1985; cota et al. 1987; cota & horne 1989; demers et al. 1989); other environmental forcing may dominate currents and mixing in mcmurdo sound, antarctica (cota & sullivan 1990). ice algae are apparently capable of storing significant amounts of phosphorus and nitrogen so that nutrient ratios and concentrations in melted bottom ice cores may exceed those in seawater (cota et al. 1990; smith et al. 1990). ammonium concentrations in bottom ice are also elevated, but about half of the nitrogen utilisation by ice algae is no3 (table 5, cota et al. 1988; harrison et al. 1990). significant internal nitrogen stores and compositional ratios (c: n, c : chl) in the redfield proportions are indicative of n sufficient populations (harrison et al. 1990). sev eral lines of evidence, however, suggest that h4si04 is likely t o be limiting for bottom ice algae in fully marine waters (cota et al. 1990; cota & sullivan 1990; gosselin et al. 1990). microalgal populations colonising the inters tices of sea ice represent a special situation with extreme and prolonged vertical stability where temperature, salinity and irradiance are often summary nutrient availability varies in its importance for phytoplankton growth in polar oceans. generally speaking, the antarctic is characterised by a con tinuous and ample supply of nutrients. nutrient limitation (or the potential for nutrient limitation) is apparently rare, but local depletion can occur if other growth-limiting conditions (for example water-column stability) are conducive to optimum production, biomass accumulation, and elevated nutrient demand (mitchell & holm-hansen 1991). such conditions occur in shallow coastal table 5. range and mean values for ice algal chlorophyll d (chl, mg m 2 ) . photosynthesis-irradiance parameters (p! = mgc mgchl-' h ' ) , ar = mgc mgchl-' h ' (pmol m 2 s ' ) . ' , and selected environmental properties for bottom ice assemblages under low snow cover from barrow strait, nwt, canada and mcmurdo sound. antarctica in 1985 and 1986. temperature ( i ) = "c, nol & nh4 concentration = mmol m i q pnhl & pnhi = mmol m ] h ' , f-ratio = pno,/(pnol + pnh,). no. obs minimum maximum mean pe lp t chl nol* conc. nol** conc. nh,'" conc. h4si04* conc. pnoi p n h ~ f-ratio 60 60 60 96 9s 14 14 95 s2 so 45 0.01 0.002 1.90 4.5 1.80 3.91 4.05 2.90 0.02 0.05 0.08 1.80 0.362 -1.80 182.0 12.3 123.40 40.39 14.40 80.04 36.15 0.92 0.37 0.050 -1.85 68.9 18.3 40.3y 16.38 6.90 6.05 3.45 0.53 concentrations based on bottom 3-5 cm of ice cores, resolute 1985 (cota et al. 1990). directly comparable measurements were not available from the antarctic. * * concentrations based on bottom 1-3cm of ice cores, resolute 1985 and 1986 (harrison et al. 1990). directly comparable measurements were not available from the antarctic. 100 w. g. harrison & g. f. cota waters, along receding ice edges and in under-ice (epontic) communities where vertical stratifi cation is more persistent or prolonged. t h e gen erally more favorable growth conditions in the northern ocean, i.e. water-column stability (e.g. dunbar 1968). combined with lower overall nutri ent concentrations result in nutrient depletion being a common feature in subarctic a n d arctic surface waters, in open waters as well as along ice edges. in both polar regions. factors other than nutrients are apparently most important in the initiation of growth whereas nutrients may be relegated t o a more secondary role of sustaining growth and setting the upper limit o n biomass accumulation. studies t o date have provided a convincing picture of the interaction of ocean physics and phytoplankton as manifest through the supply of nutrients for growth. in both polar oceans, physically-mediated nutrient supply (“new” pro duction, eppley & peterson 1979) is more impor tant than at lower latitudes (fig. 8). accounting for over 50% of the total primary production. particularly in the marginal ice zones (smith & nelson 1990). this high proportion of new pro duction, however, is not commensurate with the level of primary production predicted if nutrient limitation were the only consideration (fig. 9). clearly, other factors come into play in setting the upper limits o n polar productivity, even in nutrient availability 1 . o biological 0 l 2 0 . 5 l i controls i i “1 l o w lalilud. high l.1ilyd. 0 . 0 i 4 temp fig. x. schematic representation of the relative importance of physical and hiological sources of nutricnts for phytoplankton growth along a latitudinal axis. [n] = surface nutrient con centration. temp = seawater temperature. physical sources (”new“ nutrients) are scaled by the f-ratio (eppley & peterson 197y) and rangc from approximately 0.1 (10% of total) in tropical oceans to approximately 0.6 (60% of total) in polar oceans. “regenerated” nutricnts (biological sources) make up the halance 0 6 a o 2 0 1 y o 0 0 / i i i i i i 0 i 2 3 4 5 6 p r i m a r y p r o d u c t i o n (gc m-2 d 1 ) f i g . 9. relationship between f-ratio (ncw/total nitrogen pro duction) and total primary production. open symbols and curve = temperate/tropical data (eppley & peterson 1979); closed symbols = polar data. circles are pelagic studies. triangles are ice cdge studies (smith & nelson 1990). the arctic where nutrient depletion is prevalent. nonetheless, the close link between new pro duction and the export (and redistribution) of biogenic materials (eppley & peterson 1979) points to t h e importance of nutrient-phyto plankton relationships in developing a better understanding of the role of polar oceans in global biogeochemical cycles (dugdale & wilkerson 1989; jones e t al. 1990; smith & sakshaug 1990). the so-called “biotic” factors have received surprisingly little attention in studies of polar phytoplankton (el-sayed 1984; holm-hansen 1985). in view of the large proportion (almost half) of the primary production that is supported by locally regenerated nutrients ( n h 4 , urea), despite often high “new” nutrient (no,) con centrations, attempts to model polar phyto plankton growth dynamics will be incomplete until plankton food web interactions (both in terms of grazing losses and nutrient resupply) a r e incorporated. references alcxander. v. & niebaucr. h . j . 1981: occanography of the eastern bering sea ice-edge in spring. l i m n d . oceanogr. 26, 1 i 1 1-1 1 2 5 . alexander. v & niehauer. h . j . 1989: recent studies of phytoplankton blooms at the ice edge in the southeast bering sea. rupp. p . . i i . rcun. cons. inr. e x p l o r . m e r 188. 91107. anderson. g . c . . parsons. t. r . & stephens. k . 1969: nitrate distribution in the subarctic northeast pacific ocean. deep sea res. 16. 329-334. primary production in polar waters 101 bainbridge. a. e. 1976a: geosecs atlantic final hydro graphic data report. geosecs operations group. scripps institution of oceanography, la jolla. california. bainbridge. a . e . 1976b: geosecs pacific final hydrographic data report. geosecs operations group, scripps insti tution of oceanography, la jolla, california. banse, k. 1990: does iron really limit phytoplankton pro duction in the offshore subarctic pacific? limnol. oceanogr. banse. k. 1991: iron availability, nitrate uptake. and exportable production in the subarctic pacific. j. geophys. res. 96,741 748. berger. w. h. 1989: global maps of ocean productivity. pp. 429-455 in berger, w. h., smetacek. v. s. & wefer, g. (eds.): productivify of the ocean: present and past. wilcy intencience, new york. brzezinski, m. a . 1985: the si:c:n ratio of marine diatoms: interspecific variability and the effect of some environmental variables. j. phycol. 21. 347-357. buckley, j . r., g a m m e l s r ~ d , t., johannessen. j . a.. johan nessen. 0. m. & reed. l. p. 1979: upwelling: oceanic structure at the edge of the arctic pack ice in winter. science 203, 165-167. buma, a. g. j., nolting, r . f. de baar, h . j . w. & cadee. g. c. 1990: testing the iron limitation hypothesis for phy toplankton from the southern ocean. eos 71, 67. campbell, j. w. & aarup. t. 1989: photosynthetically available radiation at high latitudes. limnol. oceanogr. 34,149ck1499. codispoti, l. a. & richards, f. a. 1968: micronutrient dis tributions in the east siberian and laptev seas during summer, 1963. arctic 21, 67-83. codispoti. l. a , , freiderich. g . e . . whaling, p. & fri ebertshauser. m. e. 1990: some implications of the nutrient observations made during the 1989 cearex experiment. eos 71, 79. collos, y. & slawyk. g. 1986: "c and "n uptake by marine phytoplankton -1v. uptake ratios and the contribution of nitrate to the productivity of antarctic waters (indian ocean sector). deep-sea res. 33, 1039-1051. cota. g. f. & horne. e. p. w. 1989: physical control of ice algal production in the high arctic. mar. ecol. prog. ser. 52. 11 1-21. cota, g. f. & sullivan, c . w. 1990: photoadaptation. growth and production of bottom ice algae in the antarctic. j. phycol. 26, 399-411. cota, g. f . . prinsenberg, s . j . , bennett, e. b.. loder, j. w., lewis, m. r.. anning. j. l., watson, n. & harris, l. r. 1987: nutrient fluxes during extended blooms of arctic ice algae. j. geophys. res. 92, 1951-1962. cota, g. f., sullivan, c . w. & priscu, j . c . 1988: uptake of inorganic nitrogen by ice algae in mcmurdo sound. antarc tica. eos 69, 1104. cota, g. f.. anning, j . l., harris, l. r.. harrison, w. g. & smith, r. e. h . 1990: the impact of ice algae on inorganic nutrients in seawater and sea ice in barrow strait. nwt. canada during spring. can. 1. fish. aq. sci. 47. 1402-1415. dayton, p. k.. watson, d.. palmisano, a , , barry, j. p.. oliver, j. s. & rivera, d. 1986: distribution patterns of benthic microalgal standing stock at mcmurdo sound. antarctica. polar biol. 6, 207-213. demers. s . , legendre. l.. maestrini, s. y.. rochet. m. & ingram, r. g . 1989: nitrogenous nutrition of sea-ice mic roalgae. polar biol. 9. 377-383. diekmann, g.. sullivan, c. w. & garrison, d. l. 1990: 35, 772-775. seasonal standing crop of ice algae in pack ice of the weddell sea. antarctica. eos 71. 79. dugdale, r. c . & goering. j . j . 1967: uptake of new and regenerated forms of nitrogen in primary productivity. limnol. oceanogr. 12. 196206. dugdale. r. c. & wilkerson, f. p. 1989: regional perspectives in global new production. pp. 289-308 in denis. m. m. (ed.): oceanologie, actualite et prospective. centre d'oceanologie de marseille. dunbar, m. j . 1968: ecological development in polar regiom. prentice-hall, englewood cliffs. n.j. dunton. k. h. 1985: growth of dark-exposed laminaria suc charina (l.) lamour, and laminaria solidungula j . ag. (lamipariales: phaeophyta) in the alaskan beaufort sea. 1. exp. mar. biol. ecol. 94, 181-189. el-sayed, s. z. 1971: observations on phytoplankton bloom in the weddell sea. pp. 301-312 in llano. g. & wallen, i. (eds.): biology ofthe antarctic seas. am. geophys. union., washington, d.c. el-sayed, s. z. 1984: productivity of antarctic waters: a reap praisal. pp. 19-34 in holm-hansen, 0.. bolis. l. & gilles, r. (eds.): marine phytoplankton and productivity. springer verlag, berlin el-sayed. s. z. 1988: the biomass program. oceanur 31, el-sayed, s. z. & taguchi, s. 1981: primary production and standing crop of phytoplankton along the ice-edge in the weddell sea. deep-sea res. 28, 1017-1032. english, t . s. 1961: some biological observations in the central north polar sea. drift station alpha. 1957-1958. arct. fnst. n . a m . res. paper 13, 8-80, eppley. r. w. & peterson, b. j. 1979: particulate organic matter flux and plankton new production in the deep ocean. nature 282, 677-680. fogg, g. e. 1977: aquatic primary production in the antarctic. phil. trans. r. soc. lond. 8279. 27-38. gilbert. p. m., biggs, d. c. & mccarthy. j. j. 1982: utilization of ammonium and nitrate during austral summer in the scotia sea. deep-sea res. 29, 837-850. gosselin, m. l.. legendre, l.. demers, s . . ingram. r. g. 1985: responses of sea-ice microalgae to climatic and fort nightly tidal energy inputs (manitounuk sound, hudson bay). can. 1. fish. aquat. sci. 42, 999-1006. gosselin, m., legendre, l.. therriault, j-c. & demers. s. 1990: light and nutrient limitation of sea-ice microalgae (hudson bay. canadian arctic). j. phycol. 26,22&232. hameedi. m. j. 1978: aspects of water column primary pro ductivity in the chukchi sea during summer. mar. biol. 48, 37-46. hansell, d. a , . goering. j. j . . walsh. j. j.. mcroy, c. p.. coachman. l. k . & whitledge. t. e. 1989: summer phy toplankton production and transport along the shelf break in the bering sea. cont. shelf res. 9. 1085-1 104. harrison, w. g. 1983: the time-course of uptake of inorganic and organic nitrogen compounds by phytoplankton from the eastern canadian arctic: a comparison with temperate and tropical populations. limnol. oceanogr. 28, 1231-1237. harrison, w. g. & platt, t. 1986: photosynthesis-irradiance relationships in polar and temperate phytoplankton popu lations. polar biol. 5 . 153-164. harrison. w. g., platt. t. &irwin. b. 1982: primaryproduction and nutrient assimilation by natural phytoplankton popu lations of the eastern canadian arctic. can. 1. fish. a q . sci. 39,335-345. 7 5 7 9 . , 102 w. g. harrison & g. f. cota harrison, w. g . , head. e j . h . . conovcr. r . j . . longhurst. a. r. & sameoto. d . d 1985. the distribution and metab olism of urea in the eastern canadian arctic. deep-sea res. 32. 2 3 4 2 . harrison. w. g . . cota. g . f. & smith. r e . h . 1990: nitrogen utilization in ice algal communities of barrow strait. north west territories. canada mar. ecol. prog. ser. 67.27s283. hart. t. j . 1934: on the phytoplankton of the south-west atlantic and bellingshausen sea disc. rep. 8 . 1-268. hayes. p. k.. whitaker. t. m. & fogg. g . e . 1984: the distribution and nutrient status of phytoplankton i n the sou thern ocean between 20" and 70" w. polar biol. 3 . 153-165. holm-hansen, 0. 1985: nutrient cycles in antarctic marine ecosystems. pp. 6-10 in siegfried. w. r . . condy. p. r. & laws. r. m. (eds.): anturctic nutrient cyclesand food webs. springer-verlag. berlin holm-hansen. 0.. el-saved. s. z.. franceschini, g . a . & cuhel, r. l. 1977: primary production and factors controlling phytoplankton growth i n the southern ocean. pp. 11-50 in llano, g . a . (ed.): adaptations within antarctic ecosystems. gulf publ. co., houston. holm-hansen. 0 , mitchell. b. g . . hewes. c . d . & karl. d. m. 1989: phytoplankton blooms in the vicinity of palmer station. antarctica. polar eiol. 10. 49-57. horner. r . a. & schrader. g . c. 1982: relative contributions of ice algae. phytoplankton and benthic microalgae to primary production in nearshore regions of the beaufort sea. arctic 35, 485-503. irwin. b.. hodgson. m.. dickie. p & platt. t. 1978a: phy toplankton productivity experiments in baffin bay and adjac ent inlets 22 aug. to 18 sept. 1977. fisheries and marine service data report. no. 8 2 . irwin. b., evans, p. & platt. t. 1978b: phytoplankton pro ductivity expenments and nutrient measurements in the lab rador sea from 15 oct. to 31 oct. 1977. fisheries and marine service data report, no. 83. irwin. b., evans. p & dickie. p. i978c: phytoplankton pro ductivity experiments and nutrient measurements in the lab rador sea from 11 february to 28 february 1978. fishecies and marine service datu report. no. 114. irwin. b.. platt. t.. harrison. w . g . . gallego,. c . l. & lindley. p. 1982: phytoplankton productivity experiments and nutri ent measurements in ungava bay nwt from 1 august to 3 september. 1979. fisheries and marine service data report. no. 287. irwin. b . . harris. l.. hodgson, m . , horne. e. & platt. t. 1983: primary productivity and nutrient measurements in northern foxe basin. nwt from 27 august to 7 september 1981. fisheries and marine service duta report, n o . 385. irwin. 9.. dickie. p . . lindlcy. p. & platt. t. 1984: phy toplankton productivity in lancaster sound and approaches during the summer of 1979. fisheries and marine service data reporr. no 423 irwin. b.. platt. t . & ca\crhill, c . 1985: primary production and other related measurements i n the eastern canadian arctic during the summer of 1983. fisheries and marine service data report. no 510. irwin. 8.. caverhill. c . . dickie. p.. hodgson. m. & platt, t. 1986a: primary productivity of ice algae on the labrador shelf from 16 march to 27 march 1984. fisheries and marine service data report. no. 559. i r w i n . b.. cavcrhill. c . . dickie. p.. hornc. e . & platt. t. 1986b: primary productivity on the labrador shelf during june and july 1984. fisheries and marine service data report. no. 5 7 7 . irwin. b.. hornc. e . p. w.. boulding, e. & platt, t. 1987: phytoplankton productivity in jones sound during august and september 1984. fisheries and marine seroice data report. no. 676. irwin. 9.. dickic. p.. hodgson. m. & platt. t . 1988: primary production and nutrients on the labrador shelf, in hudson strait and hudson bay in august and september 1983. fish eries and marine service data report. no. 692. irwin. b.. caverhill. c.. mossman. d., anning, j . , horne, e . & platt. t. 1989: primary productivity on the labrador shelf during july 1985. fisheries and marine service data report, no. 7 6 0 ivanoff. a. 1977: oceanic absorption of solar energy. pp. 47 71 in kraus. e. 9. (cd.): modelling and prediction of the upper layers of the ocean. pergamon prcss. oxford. iverson. r. l . , whitledge. t. e. & gocring, j . j . 1979: chloro phyll and nitrate fine structure in the southeastern bering sea shelf break front. nature 281, 664466 jacques. g . 1983: some ecophysiological aspects of the ant arctic phytoplankton. polar eiol. 2 . 27-33. jacques, g . 1989: primary production in thc open antarctic ocean during the austral summer. a review. vie milieu 39, 1-17. jennings. j . c . . j r . . gordon. l. i . & nelson. d. m. 1984: nutrient depletion indicates high primary productivity in the weddell sea. nature 308. 51-54. johannessen. 0. m.. johannessen. j . a,. svendsen. e. a. s . , shuchman. r. a , . campbell, w. j . & josberger. e. 1987: ice edge eddies in the fram strait marginal ice zone. science 236. 427429. jones. e. p.. nelson. d . m. & treguer, p. 1990: 7. chemical oceanography. pp. 407476 in smith. w. 0. jr. (ed.): polar oceanography part e : chemistry. biology and geology. aca dcmic press. new york. kamykowski. d. & zentara, s.-j. 1985: nitrate and silicic acid in the world ocean: patterns and processes. mar. ecol. prog. ser. 26. 47-59. kamykowski. d. & zentara. s.-j. 1989: circumpolar plant nutrient covariation in the southern ocean: patterns and processes. mar. ecol. p r o g . ser. 5 8 . 101-111. koike. i . . holm-hansen, 0. & biggs, d . c. 1986: inorganic nitrogen metabolism by antarctic phytoplankton with special reference to ammonium cycling. mar. ecol. prog. ser. 30. 105-1 16. kristiansen. s . & lund. b. a . 1989: nitrogen cycling in the barents sea i. uptake of nitrogen in the water column. deep-sea res. 36. 255-268. le jehan, s . & treguer, p. 1985: the distribution of inorganic nitrogen. phosphorus. silicon and dissolved organic matter in surface and deep watcrs of the southern ocean. pp. 22-29 in siegfried, w. r . . condy. p. r . & laws, r . m. (eds.): antarctic nutrient cycles and food webs. springer-verlag. berlin. lewis. m. r. 1989: the variegated ocean: a view from space. new scientist 124. 3 7 4 0 . llano. g . a. 1978: polar research: a synthesis with special refcrence to biology. pp. 27-61 in llano. g . a. (ed ): polar research: to the present, and the future. aaas selected symp. 7. westview press. macdonald. r . w.. wong. c. s. & erickson. p. e . 1987: the distribution of nutrients in the southeastern beaufort sea: implications for water circulation and primary production. j . geophys. res. 92. 2939-2952. maestrini. s. y . . rochet. m., legendre. l.. demers. s. 1986: nutrient limitation of the bottom-ice microalgal biomass primary production in polar waters 103 (southeastern hudson bay, canadian arctic). limnol. oce anogr. 31 ~ 969-982. martin, j. h. 1990: glacial-interglacial c 0 2 change: the iron hypothesis. paleooceanogr. 5 , 1-13. martin, j . h. & fitzwater. s. 1988: iron deficiency limits phy toplankton growth in the north-east pacific subarctic. nature martin. j . h . & gordon, r. m. 1988: northeast pacific iron distribution in relation t o phytoplankton production. deep sea res. 35, 177-196. martin, j. h., broenkow, w. w., fitzwater, s. e. & gordon, r. m. 1990a: yes it does: a reply to the comment by banse. limnol. oceanogr. 35, 775-777. martin, j. h. & gordon, r. m. & fitzwater. s. 1990b: iron in antarctic waters. nature 345, 156158. mcroy. c. p. & goering. j. j. 1976: annual budget of primary production in the bering sea. mar. sci. comm. 2 , 255-267. mcroy, c. p., gwring, j. j. & shiels. w. e. 1972: studies of primary productivity of the bering sea. pp. 199-216 in takenouti, a. (ed): biological oceanography of the northern north pacific ocean. idemitsu shoten, tokyo. mitchell. b. g. & holm-hansen. 0. 1991: observations and modeling of the antarctic phytoplankton crop in relation to mixing depth. deep-sea res. 38. 981-1007. muller-karger, f. & alexander, v. 1987: nitrogen dynamics in a marginal sea-ice zone. conr. shelf res. 7 . 805-823. nemoto, t. & harrison, g. 1981: high latitude ecosystems. pp. 95-126 in longhurst, a. r. (ed.): analysis of marine ecosystems. academic press. london. nelson, d. m. & gordon. l. i. 1982: production and pelagic dissolution of biogenic silica in the southern ocean. geochim. cosmochim. acta 46. 491-501. nelson, d. m. &smith, w. 0.. j r . 1986: phytoplankton bloom dynamics of the western ross sea ice edge 11. mesoscale cycling of nitrogen and silicon. deep-sea res. 33,1389-1412. nelson, d. m., smith, w. 0.. j r . , muench, r. d.. gordon, l. i . , sullivan, c. w. & husby, d. m. 1989: particulate matter and nutrient distributions in the ice-edge zone of the weddell sea: relationship to hydrography during late summer. deep sea res. 36, 191-209. olson, r. j . 1980: nitrate and ammonium uptake in antarctic waters. limnof. oceanogr. 25, 1064-1074. pickard, g. l. 1964: descriptive physical oceanography. per gamon press, new york. priddle, j . . hawes. i. & ellis-evans, i . c . 1986: antarctic aquatic ecosystems as habitats for phytoplankton. b i d . reo. 6 1 , 199-238. reeburgh. w. s. 1984: fluxes associated with brine motion in growing sea ice. polar biol. 3, 29-33. reid, j. l. 1962: on circulation, phosphate phosphoruscontent. and zooplankton volumes in the upper part of the pacific ocean, limnol. oceanogr. 7, 287-306. rey, f. & loeng, h . 1985: the influence of ice and hydro graphic conditions on the development of phytoplankton in the barents sea. pp. 49-64 in gray. j . s . & christiansen. m. e. (eds.): marine biology of polar regions and effects of stress on marine organisms. j . wiley & sons, chichester. rey, f. & skjoldal, h. r . 1987: consumption of silicic acid below the euphotic zone by sedimenting diatom blooms in the barents sea. mar. ecol. prog. ser. 36. 307-312. rey, f., skjoldal, h . r . & slagstad, d. 1987: primary pro duction in relation to climatic changes in the barcnts sea. pp, 29-46 i n loeng, h. (ed.): the effect of oceanogruphic conditions on distribution and population dynamics of com mercial fish stocks in the barenrs sea. proc. 3rd soviet 331. 341-343. norwegian symp., murmansk. 26-28 may 1986. institute of marine research, bergen. rivkin. r . b., putt. m., alexander, s. p., meritt. d. & gaudet, l. 1989: biomass and production in polar planktonic and sea ice microbial communities: a comparative study. mar. biol. 101, 273-283. ronner. u.. sorensson. f. & holm-hansen. 0. 1983: nitrogen assimilation by phytoplankton in the scotia sea. polar biol. 2, 137-147. sakshaug, e. 1989: the physiological ecology of polar phy toplankton. pp. 61-89 in rey. l. & alexander, v. (eds.): proc. 6th conf. com. arct. lnternatll3-i5 may 1985. e. j . brill, leiden. sakshaug. e. & holm-hansen, 0. 1984: factors governing pelagic production in polar oceans. pp. 1-18 in holm-hansen, o . , bolis. l. & gilles, r. (eds.): marine phyroplankron and productioify. springer-verlag, berlin. sambrotto, r. n., niebauer. h. j., goering. j . j. & iverson, r . l. 1986: relationships among vertical mixing. nitrate uptake, and phytoplankton growth during the spring bloom in the southeast bering sea middle shelf. conr. shelfres. 5 , 161-168. slawyk. g. 1979: "c and "n uptake by phytoplankton in the antarctic upwelling area: results from the antiprod i cruise in the indian ocean sector. aust. j . mar. freshwater res. 30. 431-448. smith, r. e. h.. anning, j . , clement, p. & cota, g . 1988: abundance and production of ice algae in resolute passage, canadian arctic. mar. ecol. prog. ser. 48. 251-63. smith, r. e. h.. harrison, w. g . , harris, l. r . & herman, a. w. 1990: vertical fine structure of particulate matter and nutrients in sea ice of the high arctic. can. j . fish. aquar. sci. 47. 1348-1355. smith, s. l., smith, w. 0.. jr., codispoti, l. a . & wilson, d. l. 1985: biological observations in the marginal ice zone of the east greenland sea. j . mar. res. 43, 693-717. smith, w. 0.. jr.. 1987: phytoplankton dynamics in marginal ice zones. oceanogr. mar. biof. ann. reu. 2s. 11-38, smith, w. 0.. jr. & kattner. g. 1989: inorganic nitrogen uptake by phytoplankton in the marginal ice zone of the fram strait. j . cons. perm. int. explor. mer 188. w 9 7 . smith, w. 0.. j r . &nelson. d. m. 1985: phytoplankton bloom produced by the receding ice idgc in the ross sea: spatial coherence with the density field. science 227. 163-166. smith.w. o . . j r . & n e l s o n , d . m. 1986: lmportanceoficeedge phytoplankton production in the southern ocean. bioscience smith. w. 0.. jr. &nelson. d. m . 1990: phytoplankton growth and new production in the weddell sea marginal ice zone during austral spring and autumn. limnol. oceanogr. 35. 809-821. smith, w. 0.. jr. & sakshaug, e. 1990: polar phytoplankton. pp. 477-525 in smith, w. o., jr. (ed.): polar oceanography part b : chemistry, biology and geology. academic press. new york. sommer. u. 1986: nitrateand silicate-competition among ant arctic phytoplankton. mar. biol. 91. 345-351. spies, a.. brockmann, u . h . & kattner, g . 1988: nutrient regimes in the marginal ice zone of the greenland sea in summer. mar. ecol. prog. ser. 47. 195-204. stefansson. u. & olafsson. j . 1990: anomalous silicate-nitrate relationships associated with phaeocystis pouchetii blooms. eos 71, 66. subba rao. d. v. & platt. t. 1984: primary production of arctic waters. polar biol. 3, 191-201. 36, 251-257. 104 w. g. harrisori & g. f. cora sverdrup. h . u . 1955: the place of physical oceanography in oceanographic research. j mar. res. 1 4 . 287-293. thingstad. t f. & sakshaug. e. iw: control of phy toplankton growth in nutrient rccyling ecosystems. theory and terminology mar e c o l . prog. res. 6 3 . 261-272 treguer. p.. kamatani, a . gucnelc). s. & queguiner. b. 1989: kinetics of dissolution of antarctic diatom frustules and the biogeochemical cycle of silicon in the southern ocean. po/ar biol 9 . 397-403. walsh. j . j . . mcroy. c. p.. coachman. l . k . . gocring. j . j . . nihoul. j . j . whitledge. t. e . . blackburn. t . h . . parkcr. p. l.. wirick. c . d.. shuert. p. g . . grebmeier. j . m.. springer. a . m.. tripp. r d . , hansell. d. a , . djenidi. s . . deleersnijder. e , henriksen. k . . lund. b. a , . andersen. p.. muller-karger, f. e. & dean. k. 1989: carbon and nitrogen cycling within the bering/chukchi seas: source regions for organic mattcr effecting a o u demands of the arctic ocean. prog. oceanogr. 22. 277-359, welch. h. e . & bergmann. m . a . 1989: seasonal developmcnt of ice algae and its prediction from environmental factors near resolute. n.w.t.. canada. can. j . fish. aquar. sci. 4 6 . 1793-1803. welch. h . e.. bergmann. m. a , . sifcrd. t . d. & amarulik, p. s. 1 9 9 1 : the seasonal development of ice algae near chesterfield inlet. n.w.t. canada. can. j. fish. aquar. sci. i n press. wheeler. p. a . & kokkinakis. s. a . 1990: inhibition of nitrate uptake by submicromolar ammonium in the oceanic subarctic pacific: ammonium recycling limits new production. lirnnol. oceanogr. 3 5 . 1267-1278. whitledge. t . e . . reeburgh. w. s. & walsh. j . j 1986: seasonal inorganic nitrogen distributions and dynamics in the southeastern bering sea. con[. shelf res. 5 , 109-132. zentara. s.-j. & kamykowski. d. 1977: latitudinal relationship among temperature and selected plant nutrients along the west coast of north and south america. 1. mar. res. 35. 321-337. barents sea drift ice characteristics * torgny vinje and a n u n d s . kvambekk vinje t. & kvambekk as. 1991: barents sea drift ice characteristics. pp. s9-68 in sakshaug. e . . hopkins. c. c. e. & britsland. n . a . (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim. 12-16 may 1990. polar research l o ( / ) . a short review of the ice field characteristics in the barents sea is given. a digitised ice distribution data set covering the period 1 9 6 6 8 8 has been used to calculate the probability distribution of sea ice and temporal trends. the ice-covered area between 68 and 83"n and 10 and w e at the end of the melting season is found to have been reduced by 40% during the last 23 years. the maximum extension, however. shows no significant decrease over the same period, and this indicates that there might have been a reduction/increment in the ice thickness/melting effects in the barents sea during the last 23 years. torgny vinje and anund s . k u a m b e k k . norsk polariistitutt, p.o. box 158. n-1330 oslo lufthalm. n o r w a y . introduction the sea ice conditions in the different marginal seas bordering the arctic ocean are determined by dynamic and thermodynamic processes charac teristic for each area. in addition, the exchange with the arctic ocean may influence, and in some cases dominate, the age-composition of ice in the various seas. the physical boundaries of the different marginal seas are in this connection of major importance. the western and southern parts of the ice fields of the barents sea are bounded by the warmer currents spreading north and eastwards from the norwegian sea. towards the east there is a relatively large opening to the kara sea between frans josef land and novaja zemlja; this facilitates the exchange of ice masses with the neighbouring sea in this area. the bound ary towards the north is linked by a number of islands which to some extent govern the exchange of ice with the arctic ocean. the ice drift in the barents sea is mainly wind driven. the exchange of ice with the kara sea and the arctic ocean may thus vary considerably from year to year in accordance with changes i n the general atmospheric circulation. this exchange in turn determines to a large extent the amount of ice that remains in the barents sea through the subsequent summer. the com position of the ice fields may therefore at times be very complex, consisting of local and imported ice of various ages. glaciers in frans josef land and svalbard feed * norsk polarinstitutt contribution no. 275. icebergs to the area. this occurs at a highly vari able rate, mainly determined by the surging activity. the subsequent distribution of icebergs is determined by the prevailing wind field. an extreme event occurred in the spring of 1929 when about 20 icebergs were observed along the coast of finnmark (hoe1 1962). distribution the denser, warmer modified atlantic water fills up the deeper part of the barents sea. the south ward extension of the sea ice is therefore during the cold season indirectly, topographically con trolled i n the western part, where the bottom topography shows marked shelf breaks. similarly well-defined shelf breaks do not exist in the east ern part. contingent upon the intensity of the governing dynamic and thermodynamic pro cesses, the increasingly cooled water flowing east ward from the norwegian sea may here dive under the polar water at quite different latitudes. these features are reflected in the increasing variability of the ice edge position in the eastern part of the barents sea (fig. 1). the degree of cooling of the warmer water masses entering the southern area from the west as well as the ice formation during the cold season are determined by the atmospheric and oceanic circulation. the position and the intensity of the barents sea low are in this regard of particular importance. prevailing westerly/easterly winds will for example cause less/more ice formation in 60 torgny vinje & a n w i d s . kvambekk fir 1 . the probability of encountering sea ice at the end of april in the barents sca. we note the eastward increasing variability in the ice edge position. from satellite-based ice maps during 19661988. mainly from the norwegian meteorological institute ( d n m i ) . the n a v y n o a a joint ice center. i: s . a . . and observations from ships and aircraft collected by norsk polarinstitutt. this area and accordingly determine the position of the ice edge (vinje 1976-1982). t h e effect of heat transfer from the warmer water masses flowing in from t h e west is illustrated by a cor respondence between temperature anomalies at the kola meridian oceanographic section and anomalies in the ice extension in the barents sea (saetersdal & loeng 1984). loeng et al. (1983) also found that oceanic temperature changes in the eastern part will occur o n e year later than in the western part. helland-hansen & nansen (1909) found similar indications, mainly that cli matic variations in the barents sea lagged o n e year with respect to the lofoten section. oceano graphic features will accordingly play an impor tant role in long-term ice forecasting. if the barents sea low center is located in the central part of the barents sea, and if the barents sea drift ice characteristics 61 circulation is more intense than normal, we will have an increased surface speed of warmer water as well as relatively high atmospheric tem peratures and northward drift in the eastern part of the barents sea. this was the case, for example, in march 1985 when there occurred a broad opening, extending up to the northernmost tip of novaja zemlja (dnmi ice maps). if on the other hand the air pressure is high during the freezing season, there will be a retarding effect on the eastward flowing warmer water, and cold, continental winds may favour the cooling and freezing over of large areas. this happened in 1979 when an extreme western position of the ice edge was observed towards the end of the freezing season (vinje 1980). a deviation from the mean ice limit has a traceable persistency in the barents sea over a period of 2-3 months (lemke 1980). this impor tant prognostic feature, here given a statistical number, is so predominant that it has for a long time (on an empirical basis) been used for the planning of expeditions t o the area. the seasonal variation of the ice-covered area of the barents sea and the adjacent part of the arctic ocean shows great interannual variations (fig. 2 , area: 6gon-83"n, lve-55"e). the 1970 1975 1980 1985 1970 1975 1980 1985 year fig. 2. annual ice-covered area in the barents sea and the adjacent part of the arctic ocean (68n-83"n. 10e-55"e). as observed for the period 1966-1988 at the end of april (upper) and at the end of august (lower). the database is the same as for fig. 1 . seasonal variation of the sea ice distribution shows a maximum/minimum extension in late april/ august, respectively. the ice-covered area in late april was during 1973-1976 about 700,000 km2 and about 1150,000 km2 in 1969 and 1979, revealing a vari ation of as much as 400,00~500,000 km2 in the annual maximum extension over a period of four years. it is noted that the variability in the maxi mum extension is far greater than the variability in the minimum extension. the barents sea south of 80"n has been com pletely ice free for one or two months in 1972, 1976, 1984, 1985, and 1986. the long-term vari ation from the turn of the century indicates that the extension at the end of the melting season has been reduced markedly (sear 1988). a cor responding yearly reduction of 5.4 2 2.7 km?/ year is found from correlation studies for the last 23 years (1966-1988) from the area represented by fig. 2 (late august). thus, the minimum ice extension in our area has been reduced by as much as 40% during this period. the maximum extension (late april), however, shows no signifi cant change over the same period. the increasing difference between the annual minimum and maximum extension indicates that a reduction/ increment of the ice thickness/melting may have taken place in the barents sea over the two last decades. polynyas one of the main areas for polynya occurrence in the western barents sea is found in the inner part of storfjorden. when northerly winds prevail, newly formed ice is continuously transported southwards resulting in an opening outside of the rim of land-fast ice. because of the considerable ice formation that takes place, there occurs a continuous brine production which results in ver tical convection and the formation of cold, dense bottom water (midttun 1985; quadfasel et al. 1988). polynyas are also formed on the lee side of the smaller islands in the archipelago. these are consequently not stable but change position with the wind direction. hopen, kong karls land, storoya, and kvitoya are areas where polynyas may frequently develop. fig. 3 shows the prob ability of encountering open water (polynyas) in parts of these areas. ice-free areas are observed during the winter season 10%-30% of the time, 62 torgny vinje r anitnd s . k v a m b e k k storfjorden hopen week fir. 2. the probability of encountering polynyas of an) sizc at four various locations in thc barents sea for the period 1966 i y x x . the dalahase i s t h e same as for fig. 1 and the probability does not change significantly during the winter. (there is, of course. a marked peak during the melting season.) as north-northeasterly winds a r e most frequent over the area during the cold season (gorshkov & faleev 1980). a steady divergence occurs in the bng karls land 20 j o 4 0 50 week ice fields with a corresponding formation of leads (fig. 4). t h e total open areas in the ice fields of the barents sea may therefore be considerably larger than the area of the polynyas. in addition, we also have on a smaller scale t h e effect of the twice daily tidal divergences in the ice field, in this case particularly over shallow banks or near the islands. composition thickness as mentioned above, t h e ice fields may constitute quite a complex picture, containing ice of various age and origin. as the ice drift in the barents sea is mainly wind-driven, the ice exchange with the neighbouring seas is to a large extent determined by the atmospheric stress field. t h e barents sea may on an annual average be a n ice source for the arctic ocean and an ice sink for the kara sea over periods of about a decade (zacharov 1976). however, on the average, there is a seasonal variation indicating a reversed ice exchange with the neighbouring seas during t h e warmer season (vinje 1988). the dominant ice flow in the arctic is the transpolar ice drift stream which pours from 4000 to 5000 k m 3 ice per year into the greenland barents sea drift ice characteristics 63 fig. 4. infrared noaa a v h r r image showing lee polynyas and fracture patterns in the barents sea during a period with northerly winds, 27 february. 1987. sea (vinje & finnekisa 1986). (this corresponds to a fresh water supply to the greenland sea of the same order as the amazon discharge.) in comparison, the average annual transport from the kara sea to the barents sea is on the order of 500km3, and from the barents sea t o the arctic ocean only 3&40km3 per year (vinje 1988). although the latter two figures are small, their variations play an important role for the stability of the water column as well as for the local heat budget, particularly because of the shallowness of this sea. the thickest ice encountered in the barents sea is generally imported from the arctic ocean. this influx of perennial or multi-year ice may be extra large during conditions with persistent northerly winds in the region. this will affect the heat budget of the area t o a great extent, resulting in a larger extent of sea ice the following summer season. such a succession of events took place. for instance. in 1988-89 when the ice fields at the end of july 1989 showed a 60-years’ extreme southern extension of multi-year ice (volkov & vinje 1990). the thickness of the land-fast ice at hopen reached a maximum of 173 cm at the end of april during the extreme cold season of 1968-69 (vinje 1985). based on t h e relationship between the ice thickness and the accumulated degree-days at this site, we have calculated the long term average ice 7 a b k i ice t h i c k n c \ \ [ c n i ] ji bariou, l a t i t u d e 3 in t h e baren15 s e a hascd o n the o h s e r v e d r c l a t i o n \ h l p h e r w e e n ice t h i c k n e ~ a n d accurnul;itcd dcgrc.c-da!\ f o r t h e p e r d lyh7-1yxo ( a f t e r vinje 19x8) l a t i t u d e 75% 7h's 77:2 78's 7 y z n 80's t h i c k n e s s ( c r n ) y 5 105 1 3 ) 1311 145 1711 thickness that may be formed at various latitudes (table 1). the degree-days are derived from daily averages of temperature and are the sum of the number of degrees celsius below zero experi enced each day during the period of sustained frost. table 1 illustrates the effect of the considerable meridional temperature gradient in the area. we have noted that the extreme at hopen. 76.5"n, was 173 cm. comparing this figure with table 1 gives us an indication of the maximum deviation we may expect from the mean (60 cm). the multi year ice drifting in from the arctic ocean is generally 2-4 m thick. in addition there is a con siderable formation of ice in the lee polynyas to the south of the islands during conditions with northerly winds. typically. 20 cm of new ice may be formed per day during cold spells. this may result in an accumulation of about 6 m of newly frozen ice per month in the steadily unveiled water in a polynya. martin & cavalieri (1989) calculate a new ice formation of 1&17m in the polynya near frans josef land for the whole freezing season. if northerly winds prevail for some time. the result may be long lee-belts of thinner ice. bordered by thicker winter ice or multi-year ice from the arctic ocean (fig. 3 ) . thus the polynya effect may influence the ice thickness distribution in the barents sea to a considerable extent. a n additional ice producing agent is the tidal effect which twice daily opens and closes the space between the ice floes. this may cause an accumulation of frazil ice along the rim of the ice floes. illustrated bv the often observed raised ice floe edges. floe size and frrsr ice distribution wave effects produce small-sized ice floes of 10 50 m in the outer 10-50 km of the ice margin. this active disintegration zone is most narrow in areas with great water depths, while it becomes par ticularly broad i n areas where the waves are increased by a rising shelf break, for instance on spitsbergenbanken. t h e wave energy is rapidly dissipated and further inward from the active wave zone only the long waves with periods of 15-25 s penetrate; accordingly. t h e floe size also increases from several hundred metres to several kilometres. during the freezing season off-ice winds will cause divergence and refreezing between the floes. thus producing larger floes of ice breccia (ice floes consisting of smaller floes of different age). in addition, a formation of ice bands extending perpendicular t o the main edge gen erally occurs. t h e r e a r e a number of hypotheses and models indicating how these bands a r e pro duced. but so far n o single hypothesis has been generally accepted. the formation of fast ice in the barents sea occurs in sheltered areas. t h e most important places are the inner part of the storfjorden. the triangle between nordaustlandet. kong karls land and barentsoya, a n d t h e archipelago of frans josef land. a smaller, frequently recur ring. fast ice area is found over t h e shallow shelf just south of kongsoya. ridging ridging events may take place with onshore winds. rubble fields, possibly d u e t o this effect, are often observed in the n w part of the barents sea. and ice piles 10-15m high have been observed o n the shore of the islands. t h e height of the ridging is also illustrated by the fact that fairly large accumulations of ice blocks may be observed on t o p of 7-15 m high grounded icebergs (loset et al. 1988; vinje e t al. 1989). ice ridging also occurs in convergences caused by wind, cur rents. and land constraints. the most frequent ridge height observed from the meteorological station o n h o p e n is 2 m . t h e most frequent ridge density in t h e ice fields of the barents sea as observed from a long term project using aircraft is about 10 km-l. t h e frequency distribution is fairly broad. with a maximum of 26 km-' (vinje 1985). ice bottom topography the ice bottom topography has been studied extensively using a scanning sonar ( johnsen 1989). the measurements indicate that t h e multi year ice has a relatively smoother bottom top barents sea drift ice characteristics 65 . . . . --.--. . . . . /-. / / i i / / / / i 2 / fig. 5. typical bottom topography features of multi-year ice as mapped with a scanning sonar at 78.8"n and 29.7"e september 1989. the dimensions of the box are 40 m x 40 m x 10 m . the flat areas in the corners are areas with no data due to ship or ridge shadows. the grid spacing is 2 m . ography than the first-year ice in the marginal ice zone. this may reflect the effect of thermo dynamic processes having acted over a longer time period for the former ice type. a typical sample of a multi-year ice bottom topography is given in fig. 5 . an ice field is considered to have a very high oil pooling capacity due to capture in the leads, under and upon the ice floes. johnsen 8~ vinje (1987) estimated that the domes under the ice floes 10-90 km from the outer ice edge could trap as much as 0.08 m3/m2 on an average. martin et al. (1976) found in a laboratory test that 0.004 m3/ m2 oil could be pumped upon pancake ice. pan cake ice is a very common ice type in the outer 10 km of the ice margin during the freezing season. terrigenous and biogenous material in sea ice when the freezing starts in september/october, the coastal water masses contain a maximum of suspended material delivered by the run-off from a variable extent, dependent upon the con centration of suspended material and the intensity of the freezing. the occurrence of sediment-laden ice is quite common in the arctic ocean (nansen 1904,1906; thiede 1988) as well as in the barents sea. elverhgi & solheim (1983) report that the material in the latter area is both of local and external origin. this is in accordance with the influx of ice to this region from other shelf areas in the arctic. as mentioned above, the greater part of the potentially sediment-laden ice import generally comes from the kara sea. however, temporary deviations from the normal flux pat tern indicate that considerable amounts may at times also come from other parts of the siberian shelf. this was the case in 1989 (volkov & vinje 1990). another phenomenon which was observed on spitsbergenbanken in march 1987 is the accumu lation of material in ice ridges which may act as traps for material brought up under the ice by turbulent currents over shallow banks. when these newly formed, nonconsolidated ridges are land and glaciers. the material in the upper water . broken up, mud-accumulation between the ice layers will be embedded in the new frozen ice to blocks and a number of dark brown ice surfaces 66 torgriv vinje & a n u n d s . koambekk along the track of the ship may be observed. t h e observation of scattered muddy ice floes in the barents sea ice fields is not a rare event. the accumulation of bottom material trapped i n newlv formed ridges is a phenomenon that surely occurs during freezing in all shallow areas. when these ridges are consolidated during the following summer. storage of sediments as well as of nutrients, bacteria. or other biological material such as eggs and larvae will occur. being trans ported over long distances. this storage may form a basis for new biological growth in new areas during the melting season. then mainly in the marginal ice zone. the potential of an ice field to carry trapped terrigenous or biogenous material is indicated by the above-mentioned great number of ridges observed per km. garrison e t al. (1989) observed that a high concentration of organisms i n sea ice may be the result of accumulation of frazil ice. the highest concentration of organisms should accordingly be observed along the down uind border of a polynya or along the edge of ice aoes where we will have an accumulation of frazil ice. another structure-forming agent is the melting and freezing that takes place in perennial ice. freezing takes place at the bottom d u e to the conducted radiative heat loss during winter. melt ing mainly takes place on the surface due to the positive radiation balance during the summer. this repeated melting and freezing over a period of some years results in an upward transport of sediments. nutrients. and biological material. this may explain the frequent observations of very muddy surfaces or marked layering of dark material in the column of perennial ice. ice drift tidal or inertial effects play an important role for the daily movement of the ice, particularly over the shallow shelves, in passages, or along the coast. t h e movement of the ice fields d u e t o tidal or inertial effects is clearly illustrated by the trails formed by grounded icebergs (fig. 6). t h e dia meters of the loops vary between 5 km and 15 k m , depending o n the corresponding water depth and f i g 6 . trails after grounded icebergs on spitsbergenbanken caused by tidal or inertial effects in the moving ice field. landsat tm image 1 june. 1988. the loop diameter is about 15 km. barents sea drift ice characteristics 67 produce double, mushroom-shaped eddies. this has repeatedly been observed near the southern tip of hopen (vinje 1985). information on the ice drift in the barents sea has been collected mainly from ice drift buoys since 1975. to illustrate the variance caused by the passage of lows, the drift of three buoys deployed at the same time and longitude but at different latitudes can be considered (fig. 7). the wind stress. if the number of grounded icebergs is large, the grinding of ice floes may have an effect on the floe size distribution in the area. the twice-daily tidal wave causes a periodic divergence and convergence over shallow banks, near the coast or in narrow passages. this is a well-known and marked phenomenon which has been taken advantage of for a long time by ice navigators. the tidal wave may also at times 80n 75n 7 0 n o e 20e 40e 60e 20e 40e 7 5 n 7 0 n fig. 7. drift of icexair-buoys in 1986/87. the buoys were parachuted on ice roes 16 december 1986 at 76.8"n. 78.5"n. and 80.o"n along 40"e. off indicates when the buoy became afloat. note the great variety in the drift directions. the dates in the figure are day/month. (after johnsen & vinje 1987). 68 average simultaneous ice velocity in the outher margin is observed t o be about 0.2111s-i with a mean net displacement of 0.06 m s ' towards southwest (vinje 1988). according to buoy drift observations, the ice velocity amounts to 1-2% of the geostrophic wind speed (johnsen & vinje 1987). this is in agreement with wind-induced ice edge displacements such as those observed o n satellite images (vinje 1977). t h e wind effect on the ice increases towards the margin, probably because of the increased form drag d u e to wave effects (stokes drift) as well as to the scattering of ice floes. torgny vinje ce anrinti s . kiinnibekk references elvcrhei. a . & solheim. a . 1983: the barents sea ice shcet a sedimentological discussion. polar res. i . 23-42, garrison. d l . . close, a r. & reimnitz. e. 1989: algae concentrated by frazil ice: evidencc from laboratory cxperi mcnts and field experiments. a n r . s r i . i (1). 31s316. gorshkov. s . g . & f a k c \ . v . 1. (cds) 19x0: atlac ofrhe oceans the arcric oceari. ussr ministry of defensc. helland-hansen, b. & nansen. f . 1909. thc noruegian sea. fiskdir. skr ser. haciirnders. 2 ( 2 ) . 1-360. h o d , a. 1962: lsfjcll p i kysten av 0st-finnmark norsk geo grafrsk tidsskrifr s 4 , 2 2 b 2 3 8 . johnsen. a . s. 1989: relations between top and bottom ice topography using a scanning sonar p r o c . 10th con/ p o r t . and ocean engfrit'ering under arcrrc condirtoils 1. 7 7 4 6 . tekniska hsgskolan i lulei. sverigc. johnsen. a . s & virile. t 1987: havisunders~kelseri barcnts havct. a kup-proslekr 1.3. norsk polarinstitutt. oslo. 97 pp. lemkc. p 1980: application of the inverse modelling technique to arctic and antarctic sea ice anomalics. hamburger geo physrkalische e i r u e l s c h r i f r e n , reihe a . wissenschofrltche abhandlungen. heft 4y. 95 pp. loeng. h . . nakkcn, 0. & rakncs, a . 1983: loddas utbrcdelsc i barentshavct i forhold t i 1 temperaturfcltct i pcriodcn 1 9 7 6 1983. fisken or hover i . 1-17. leset. s . . vinje. t . . levas. s . m . . johnsen. a ' s . , jenscn. h.. erlingsson. b. & vefsnmo. s . 19x8: i d a p 88 vessel deplownenr. volume 2 . field ohseruarrons and a n a l w s . norwegian hjdrotechnical laborator?. trondheim. 138 pp martin. s . & cavalicri. d j 1989: contribution of the siberian shelf paltnyas 1 0 thc arctic ocean intermcdiate and deep uater j . grophis. r e s . y4 i c y ) . 12725-12738 34artin. s . kauffman. p. & wclandcr. p e. 1976. a laborator! \tuj! ot the di3persion of crude oil within scil ice grown in a ~ a \ c field proc. 27ih a l a s k o sci. con/: 2 . 261-787. fdirhanks. alaska. hlidttun. l. 1985: formation of dense hottom water i n the barcnts sea. deep-sea res. 32. 1233-1231. n a n w . f . iyoj. the bathynctrical iedtures of the north polar scac. w i t h ti discussion of the contincntal shclvcc and prcvioub owllatiom of the shore-line. pp. 1-232 i n nansen f. (cd.): 7 l i r .yorwegian norrli polar expedrriorr 1x93-lxy6. scienrific resulrs 4 ( 1 3 ) . j . dvhwad. christiania nanscn. f. iym: protozoa on the ice-floes of t h c north polar sea. pp. 1-22 i n nanscn f. (ed.): 7 h e nornvgiarr north polar €.rpedirion ixy.3-18y6. scietirific resu/r.s 5 ( 1 6 ) . j . dyhwad, chriahania. quadfascl. d . . rudela. b & kurz. k . 1988: outflow of dense water from a svalbard fjord into the fram strait. deep-sea re, 35, i i j , ~ 1 1 s i ~ . sztcrsdal. g . 8: loeng. h 1983: ecological adaption of repro duction in arctic cod. pp. 13-35 in gode. 0. r . & tilaeth, s . ( c d s . ) : proc. souier-norwegian s y m p . . reproduction arid recrrurtnem of arcrtc r o d . inatitutc of marine research, bcrgcn scar. c . b. 1988: an index of sea ice variation5 i n the nordic seas. 1. climarol. 8 . 33%355. thicdc. j . ( c d ) 1988: scientific cruise report of arctic expedition ark iv/3. reporrs on polar research ( a w l j 4 3 . 237 pp. vinje. t. iy7&1982: annual reports. norsk polarrrisrirurr a r b o k . oslo. vinjc. t. 1980: on the extreme sea ice conditions observed in the greenland and barents seas in 1979. norsk po/aririsritur! a r b o k 1979. 5%65. oslo. vinje. t . 1977: sea ice studies in the spitsbergcn-greenland area. l a n d s a t report € 7 7 1 0 2 0 6 . u . s . dcpt. of com. n a t l . info. service. 59x5 port royal rd., springrcld. v a . v1nje.t. 1985: drift. composition. morphology anddistribution of the sea ice ficlds in the barents sea. norck pohrinsrirutr skrifrer 17yc. oslo. 26 pp. vinje. t. 1988: dynamics and morphology of the barcnts sea ice fields. proc. yrh coiif. port a n d ocean engineering w i d e r arrric condirrons i . 26s-268. university of alaska fairbanks. alaska, u.s.a. v i n j c . t . & finnekisa. 0 . 1986: the ice transport through thc fram strait. norsk polarinsrirurr skrifrer 186 39 pp. vinjc. t . . j c n x n . h.. johnsen. a . s . . laset. s . . hamran. s . . l e ~ a s . s . m . & erlingsson. b. iyxy: idap-xy r i v l a n c e deplo! menr. v o l u m e 2: field obseroations arid analysis. norak polarinstitutt. oslo. 74 pp. \'olkov. v & v i n j c . t . (cds) 1990: sovict-norwcgian occano graphic programme ly8&lyy2. cruise reports 1989. norsk polarrrisrirrirr rapporrserre 5 7 . 5 5 pp zacharob. v . f 1976: cooling of the arctic and the ice cover of the arctic scas. (trsl.: norsk polarinstitutt) a a n l l t r u l f ~ l 337 gidrometcoizdat. leningrad. 96 pp. bookreviews25(2).indd 181polar research 25(2), 181–188 widely read and acknowledged. however, the fi rst and last chapters are also an interesting read and give a nice basis for evaluating the biological and ethnographic material presented in the volume’s middle section, although now and again they are redundant. the book contains an interesting and eclectic collection of black and white illustrations including portraits, historical photographs, and technical and biological drawings. otto fabricius was a cleric, philologist, naturalist and ethnographer. much of his scholarly work stems from the relatively short period of his life spent as a missionary in greenland (1768–1773). his observations during these fi ve years and the experiences he had with greenlandic people clearly left a great impression on fabricius that lasted until his death. unlike many missionaries of his time, fabricius left the european colonytown where he was posted and lived in a greenlandic inuit community. he resided in a house built of stones, turf and timbers and learned the language and the ways of the people. much of their hunting culture revolved around knowing the habits of seals, and hence the people were a wealth of knowledge to fabricius in his faunal and ethnological studies. fabricius is undoubtedly best known for his publication fauna groenlandica (1780), but the work translated by kapel in this book, published a decade later (1790–91), allowed fabricius to expand greatly on the seal material presented in the earlier book. fabricius’s detailed description of the seals of greenland focuses fi rst and foremost on the harp seal or greenland seal (phoca groenlandica), describing: nomenclature; appearance and morphology; distribution (occurrence); behaviour; variation in occurrence and movements; breeding; feeding; predators; hunting methods; utilizabook reviews review of otto fabricius and the seals of greenland. meddelelser om grønland: bioscience 55, by finn o. kapel (2005). copenhagen: danish polar center. 150 pp. isbn 87-90369-77-7. kit m. kovacs norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, kovacs@npolar.no. in this three part volume finn kapel presents us with 1) a brief biography of fabricius, 2) a translation of his treatise on the seals of greenland and, fi nally, 3) a refl ection on the contribution of fabricius as a seal naturalist/scientist. i concur with dr kapel’s belief that the key paper is the second one. this work on greenland’s pinnipeds has until now been available only in danish and german and certainly deserves to be more skull of the “hook-snouted seal”, now known as the grey seal (halichoerus grypus). the drawing illustrated fabricius’s detailed description of the seals of greenland (1791). (reproduced with permission of the danish polar center.) portrait of otto fabricius. (reproduced with permission of the danish polar center.) 182 book reviews tion; parasites; and synonyms. ringed seals (pusa hispida), harbour seals (phoca vitulina), hooded seals (cystophora cristata) and bearded seals (erignathus barbatus) are presented similarly, although more briefl y. fabricius also gives short synopses of four additional “species” reported to him by the greenlanders. three of these animals are either mythical beasts or some sort of biological oddity such as albino specimens. the fourth species summary is the fi rst scientifi c account of the grey seal (halichoerus grypus), which fabricius describes primarily from material in his possession from an island off the danish coast. given the era in which fabricius was writing, his restricted time in greenland, and limited travel in the north, his biological accounts are remarkably insightful. occasionally, they are defi nitively incorrect, such as when he says, “as for the breeding of the harp seal, the matingtime is beyond all doubt in august” when in reality harp seals mate in march. but fabricius can be forgiven for using the size of the embryo in september to back-calculate the time of mating: delayed implantation was unknown in the 1700s. other small slips can be similarly accounted for. he is probably not credited as often as his work warrants; perhaps this book by finn kapel will help correct this situation. if allen’s history of north american pinnipeds (1880) or similar books are on your shelf, otto fabricius and the seals of greenland undoubtedly also deserves a place there. references allen, j. a. 1880: history of north american pinnipeds. a monograph of walruses, sea-lions, sea-bears and seals of north america. washington, d. c.: u.s. geological and geographical survey of the territories. fabricius, o. 1780: fauna groenlandica. (fauna of greenland.) copenhagen(?): j. g. rothe, hafniae & lipsiae. fabricius, o. 1790–91: udførlig beskrivelse over de grønlandske sæle, første og andet stykke. (detailed description of the seals of greenland, parts one and two.) copenhagen: skrivter af naturhistorie-selskabet. review of le monde polaire, mutations et transitions, under the direction of mariefrançoise andré (2005). paris: ellipses– carrefours. 187 pp. isbn 2-7298-2683-1. in french. bernard lefauconnier place du mollard, f-38700 le sappey en chartreuse, france, b.lefauconnier@wanadoo.fr. as mentioned on its back cover, le monde polaire, mutations et transitions comprises part of a collection (carrefours) intended for students of geography, history and the social sciences as well as for a wider public interested in understanding the changes our world is undergoing. other volumes in the series concern, for example, water in the arab world, large cities of north america and international commerce. twelve authors have collaborated on the book. the work is divided into two parts, made up in total of 11 chapters and six brief inset texts. the fi rst part is supposed to present some general aspects of the subject, regional aspects being introduced in the second part. seven of the book’s 11 chapters concern the indigenous peoples of the circumpolar region and constitute the heart of the volume. chapter 3 explores how the inuit conceive of—and are integrated with—their environment. chapter 4 discusses the transition from a subsistence economy to the present situation in the canadian arctic, focussing on nunavik, northern québec. major social transformations are described in chapter 10, with examples from the central canadian arctic. chapter 5 describes the emergence of the sense of an inuit identity, the creation of the inuit circumpolar conference and the building of inuit managerial and administrative competence, especially in the nunavut and nunavik territories, northern canada. chapter 7 concerns the transformation of greenlandic society. the situation of the saami, the subject of chapter 8, is unusual in that this population is represented in four countries: norway, sweden, finland and russia. the relationship between the saami and the norwegian state is described. the small-numbered indigenous ethnic groups—mainly reindeer herders—of the russian arctic are briefl y presented in chapter 9. only two chapters are devoted chiefl y to the 183polar research 25(2), 181–188 physical environment: chapter 1 presents a review of some recent research on the melting of glaciers and the related sea level rise while chapter 2 discusses the impacts of climate change through the metamorphosis of polar landscapes. one chapter (6) describes the development of polar tourism and chapter 11 summarizes past and present scientifi c activities in the antarctic. the limited space allotted to the environment in this book is regrettable. impacts related to climate change are not confi ned to glaciers and landscapes. in a book with academic intentions, references to the arctic climate impact assessment and the arctic monitoring and assessment programme would have been minimally necessary. in chapter 1, one of only two chapters devoted to the environment, some of the research results that are discussed are erroneously interpreted. for example, arendt et al. (2002) estimated the contribution to sea level of alaskan glaciers from the mid-1950s to the mid-1990s to be 0.14 ± 0.04 mm per year. this is equivalent to 5.6 ± 1.6 mm over the period, not 5 cm. another example is where the chapter’s author (incidentally, also the book’s editor), referring to rignot et al. (2003), writes that patagonian glaciers contribute even more than alaskan glaciers to sea level rise. in fact, rignot et al. said that the contribution from the patagonian glaciers is larger than that of alaskan glaciers per unit area. this is an important distinction. finally, the chapter mentions glacier surging but this phenomenon is evidently not understood by the author. there are other fl aws. chapter 6 takes into account the local and regional environmental impacts of tourism but does not mention the contribution to global pollution generated by the transportation of voyagers from low latitudes to the polar areas. in two places—a short inset in chapter 10 and a section heading in chapter 4— the use of the phrase “welfare state” (état providence) seems inappropriate. the texts discuss social and economic transformations and largescale interventions by the canadian central power. the “welfare state” must have been developed to try to counter-balance negative social effects of these transformations and is not in itself the cause of these negative effects. this is a strange book. the title claims to embrace the polar world but only a single chapter concerns the antarctic. the chapters discussing the environment merely skim lightly over a narrow slice of this important topic, without any real look at current climatic changes or the fact that the arctic and antarctic have already been affected by pollution, including ecotoxins, coming from sources elsewhere in the world. even with these drawbacks le monde polaire has value: there are few books presenting a broad picture of circum-arctic peoples. social, economic and geopolitical problems and the similarities and differences in the relationships between far northern indigenous peoples and the modern states that encompass them are briefl y but, in general, clearly described. i was particularly captivated by the subject of chapter 3—“corps inuit, espace géographique et cosmologique”, which opened for me, as an occidental scientist, a new window on the arctic and enriched my vision of it. references arendt, a. a., elchemeyer, k. a., harrison, w. d., lingle, c. s. & valentine, v. b. 2002: rapid wastage of alaska glaciers and their contribution to rising sea level. sciences 297, 382–386. rignot, e., rivera, a. & cassasa, g. 2003: contribution of the patagonia ice-fi elds of south america to sea level rise. science 302, 434–437 review of the north pole, by kathan brown (2004). san francisco, ca: crown point press. 504 pp (xi-xvi). isbn 1891300-18-0. thor b. arlov research and innovation unit, norwegian university of science and technology, no-7491 trondheim, norway, thor.arlov@ntnu.no. at fi rst glance a medium brick sized book entitled the north pole seems a promising read to anyone interested in the arctic, such as this reviewer. unfortunately it does not quite deliver according to expectations, presuming you expect solid information about the polar region. if, however, you are particularly interested in the personal experiences of arctic tourists with a dash of environmental concern, this book may not be a complete waste of time. the author kathan brown is the founder and 184 book reviews director of a renowned san francisco-based fi ne art printing press and publishing house. she has previously published various books on art and artists. however, her professional or personal connection with the polar regions are, as it were, shrouded in northern mists. the introduction to the north pole is not very helpful about her motives for writing this book. it appears she took part in a trip to the north pole sponsored by the american museum of natural history aboard the russian nuclear powered icebreaker yamal in 2002. the following year, she spent a week on a coastal cruise around svalbard. her experiences during these two trips have obviously inspired the book. in addition she has read a number of works about various arctic subjects and talked to some knowledgeable people, but to call this a thoroughly researched book would be stretching it. admittedly, brown seems to have no pretences in this direction. the north pole is voluminous in pages—a little more than half a thousand. the genre is a bit diffi cult to decide as the author mixes forms. since the voyage seems to be the structuring element, i suppose the book might be placed in the travel literature category. following a brief introduction that attempts to explain the somewhat odd composition of the book, there are eight main chapters. the fi rst seven are devoted to the north pole trip on the yamal. each of them is divided into three sections: a personal narrative by the author; excerpts from the journal of fridtjof nansen from the fram expedition; and a conversation with various people rendered in verbatim form. the last chapter is on the visit to svalbard and also contains a conversation, but— quite understandably—no excerpts from nansen. in between there are more than 100 photographs, the vast majority taken by the author herself. to the extent that there are any main themes at all, the issue of climate change and the question who was the fi rst on the north pole (if indeed peary cheated) recur frequently with slight variations throughout the book. if i were to be very polite i would call this unusual lay-out interesting, but to be honest i am rather put off by what seems to be a lack of serious effort making this book. the author’s own, original contribution represents the lesser part of the manuscript. the “journey” sections written by brown make up some seventy pages, or less than 15 % of the book. the photographs, also the work of brown, constitute nearly a quarter of the book. of the remaining 60 %, the excerpts from the journal of nansen fi ll almost 100 pages. the conversations or interview sections, where brown acts as “moderator”, occupy over 150 pages. at the end of the book there is a rudimentary time line, a short bibliography and a decent index. the only map in the book is a poor sketch of the arctic. although neatly organized, this book is in effect a compilation of somewhat disparate elements. by themselves the journey sections work fairly well; brown is a good observer and masters the style of a well-read journalist. she makes a pretty good job of popularizing science. this is the kind of prose one might expect to fi nd in for example national geographic: a personal account supplemented by factual information, or vice versa. the conversation sections function less well. their consistently verbatim form leaves the question open whether editing has taken place or not. anyway, stronger editing would have been desirable—considerable parts of the conversations are just plain small talk between fellow travellers. i kept wondering why the reader is invited to listen in. some of the contributors have more to offer, but the knowledge and capacity of participants like, for instance, arctic climate impact assessment director gunther weller and scott polar research institute archivist bob headland, could have been exploited far better in more elaborate interviews. in general, brown does not seem to distinguish between the substantial and the trivial in her role as moderator. for example, rendering an exchange of opinions concerning rock bands or suvs leaves me, in this context, cold. a more selective approach would certainly not have been amiss. nansen’s journal of his and hjalmar johansen’s dramatic attempt to reach the north pole from fram and their subsequent wintering on franz josef land in 1895–96 is a classic in arctic literature, but should rather be read in the original and in extenso. brown’s excerpts seem out of context and do not lend her account authority—just extra pages. i feel the use of nansen borders on literary theft when the author does not even make the effort of paraphrasing or commenting. finally, the photographs are for the most part unimpressive and appear to be ordinary amateur snapshots. considering the author’s professional background the reproduction is disappointing; the colours seem washed out and the subjects are fre185polar research 25(2), 181–188 quently unsharp. variations on ice fl oes are only interesting to a certain point, which brown oversteps. it does not make things better that there are no captions to the pictures, leaving the reader to guess when, where and why they were taken. in all fairness, kathan brown’s the north pole is probably not intended for well-read polar enthusiasts. it is indeed hard to imagine that readers of polar research will fi nd very much of interest in this book. it is simply too superfi cial with regard the factual parts and has too little to offer in literary terms. in my opinion, neither the gracious contributions of some prominent savants of the arctic nor the extensive quoting of nansen’s diary help salvage this north pole voyage from wreckage. at the uttermost ends of the earth: the physiology of polar fi shes, edited by anthony p. farrell & john f. steffensen (2005). amsterdam: elsevier. 396 pp. isbn 0-12350446-5. andrew clarke biological sciences, british antarctic survey, high cross, madingley road, cb3 oet cambridge, uk, accl@bas.ac.uk. ecologists and physiologists have always been interested in organisms living in extreme environments because of the light they shed on fundamental problems, and the general public has long been fascinated by animals living in climates so inhospitable that unprotected humans would rapidly perish. the pioneering physiologists of the early 20th century had quickly recognized that teleost fi shes with their dilute blood would have real problems in the cold waters of the polar regions, and when johan ruud collected the fi rst scientifi c specimens of an icefi sh he was able to confi rm that there really did exist a group of polar fi shes with no blood pigment. the scene was thereby set for an exploration of the physiology of polar fi shes, and this remains a vibrant fi eld of research to this day. the latest volume of the prestigious fish physiology series brings together a group of distinguished workers in the area of polar fi sh and provides a state-of-the-art survey of our understanding of the physiology of a group of organisms that have successfully adapted to one of the most physiologically challenging marine environments on the earth. the opening chapter (devries & steffensen) provides a brief overview of the marine environment of the polar regions, emphasizing the marked differences between the arctic and antarctic as much as their similarities, and thereby defi ning an important theme for the rest of the book. as well as differences in topography, bathymetry, riverine input and oceanography, attention is drawn to the very different tectonic, climatic, glacial and evolutionary histories of the two polar regions. the latter are fundamental to understanding the very different fi sh faunas of the arctic and antarctic, which are described in exemplary fashion in the second chapter by møller, nielsen & anderson. it is refreshing to see due attention being paid to the systematic and biogeographic aspects of the fauna in a volume devoted primarily to physiology, for this is essential to any complete understanding of evolutionary aspects of the physiology. the systematic treatment also covers all depths, thereby providing a broad context for the traditional (but not universal) concentration by physiologists on the more easily sampled shallow waters. the physiological chapters start with a thorough review of current knowledge of the metabolic biochemistry of polar fi shes by pörtner, lucassen & storch. the main themes of this chapter are the central role played by oxygen in shaping both thermal limits and lifestyle, and the trade-offs inherent in the utilization of energy in a strongly resource-limited environment such as the polar seas. the strengths of this chapter are the way physiological processes are set in an environmental context, the use of a wide range of model organisms, and the links between physiology and ecology. antifreeze proteins and freezing avoidance are reviewed by devries & cheng. the physiological challenge to teleost fi sh living in polar regions was recognized in the 1960s: even with an elevated blood salt concentration, polar fi sh are under cooled by almost 1k. whilst this may seem a small interval, because polar oceans contain ice crystals freezing of these fi sh would be inevitable in the absence of a protective mechanism. the existence of antifreeze glycoproteins and proteins in polar fi sh was quickly established by elegant work by art devries himself, but almost four decades later we are still unravelling the complexities of this system. in addition 186 book reviews to providing a masterly summary of the classical work, the authors also discuss areas of active current research making this the best current review of freezing avoidance in polar fi sh. in the next chapter steffensen concentrates on the respiratory system and metabolic rate; this chapter is thus closely allied to the earlier one by pörtner and colleagues but takes a quite different perspective by concentrating on the organismal rather than the molecular level. steffensen revisits the arguments over the existence of metabolic cold adaptation (mca) in polar fi shes, and does so in a thorough and balanced manner. once a fi sh has taken up oxygen, it then needs to move this oxygen around the body and the circulatory system is described by axelsson. a major factor here is the increase in blood viscosity at low temperature, and it is likely that selection for reduced circulatory costs coupled with the increased solubility of oxygen at low temperatures is what drove the evolution of reduced hematocrit in many polar fi shes and the complete loss of haemoglobin in one group, the icefi sh family channichthyidae. a key feature of this chapter is the discussion of the control of heart rate, setting the antarctic notothenioids in the wider context of non-polar fi sh. wells covers blood gas transport and haemoglobin, principally from studies of notothenioids but also setting the results in a wider context. wells also revisits the topic of mca, coming to a less defi nitive conclusion than steffensen. davison describes the skeletal musculature and locomotion, again principally based on studies of notothenioids. data are compared with warmer water fi sh and the differences related to ecological factors such as growth rate and buoyancy. in exploring the various ways in which temperature may limit muscle performance in polar fi sh, davison also discusses the limitation of mitochondrial atp supply, which links this chapter nicely to that by pörtner and colleagues. the fi nal chapter in the book is an authoritative review of the nervous system of polar fi shes by macdonald & montgomery. how does this volume rate overall? i believe it succeeds in providing a thorough, timely and authoritative survey of the physiology of polar fi shes. it will fi nd a place in my library and i have already found myself making extensive use of it. it is a pity that not every author has taken the opportunity to cover both arctic and antarctic studies, for the book does tend to concentrate on studies of notothenioids in many places. important and interesting as these fi sh are, they are confi ned to the southern hemisphere and physiologists have much to learn from thorough comparative studies. nevertheless this is an excellent summary of current knowledge and will remain for some time the place to go to learn about the physiology of fi shes living at high latitudes. review of the north pole was here: puzzles and perils at the top of the world, by andrew c. revkin (2006). boston: kingfi sher. 128 pp. isbn 0-7534-5993-0. helle v. goldman norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, goldman@ npolar.no. ever wondered what the men’s toilet at camp borneo, a temporary russian camp on the ice about 96 km from the north pole, consists of? in the north pole was here, andrew revkin reveals this—“a waist high igloo-style wall of ice blocks” (p. 16)—and other details of the fi eld conditions experienced by scientists who carry out research near the very top of the world. using revkin’s own visit to the north pole environmental observatory—a science camp set up every year on the ice about 48 km from the north pole—as a jumping off point, the book describes the arctic and our past and ongoing efforts to understand it. climate change is a major theme. other topics, like early exploration of the region and the earth’s shifting magnetism, are also covered. in an enchanting chapter called “the imagined pole”, revkin describes early notions of the far north. we learn, for example, that in ancient hindu / buddhist cosmology, the stars in the sky were tied by ropes of wind to the north star, which was positioned above a gigantic mountain that constituted the world’s centre. four landmasses, divided by great rivers, lay around that centre. three thousand years ago, greek historians supposed that there was a society of “hyperboreans”: “an immortal race of people who lived in happiness and warmth beyond the source of the north wind” (p. 28). (this is sure to raise 187polar research 25(2), 181–188 a smile from readers who, like me, reside north of the arctic circle.) as late as the 19th century some maintained that the earth was hollow, with large openings into the interior at the north and south poles. according to another tenacious and surprisingly recent theory, the north pole was topped by a huge iron cone, which was the source of the planet’s magnetism. the bulk of the north pole was here is set in the present. revkin focusses his account on the scientists who undertake polar research, how they do it and the diverse challenges they face. one chapter begins with this riveting opening: “six of the world’s leading experts at solving arctic riddles are on their knees on the sea ice thirty miles from the north pole, stumped by three broken bolts” (p. 89). the chapter goes on to relate how the bolts were replaced and the winch repaired, and how the equipment contributes to our knowledge of the ocean, atmosphere and climate in the arctic. the heroes of revkin’s book are polar scientists and the divers, technicians and others who work with them. in the harsh environment of the arctic, research teams must combine “the brainpower of scientists with the brute strength of furniture movers, the wile of small-town mechanics, the courage (or recklessness) of extreme athletes, and the willingness to carry a shotgun to ward off polar bears” (p. 92). without oversimplifying its subject matter, the north pole was here makes science accessible to the nonspecialist reader. the slim book is aimed particularly at young adults but will also appeal to their parents. the chapters are short, the type is large and the text is amply illustrated with photographs, diagrams, maps and other illustrations. excerpts from new york times stories relating to the arctic (about half by the author) are sprinkled throughout the book. an award-winning journalist, revkin has been reporting on environmental issues for the new york times for over a decade. some readers may recognize the author’s name from his recent coverage of the bush administration’s attempt to stifl e jim hansen, director of nasa’s goddard institute for space studies, after hansen publicly called for prompt reductions in greenhouse gas emissions. the north pole was here is well timed: 2007-08 is an international polar year, during which scientifi c resources around the world will be concentrated on the arctic and antarctic. its antecedents have taken place in 1882-83, 1932-33 and 1957-58. revkin traces the polar year project back to the inspiration of the austrian karl weyprecht. upon returning from an arctic expedition in 1874, the explorer and scientist was determined to persuade the scientifi c institutions of many nations that it was crucial to coordinate meteorological and geophysical research and to share the resulting data. weyprecht’s efforts bore fruit, though it was posthumous: he died the year before the fi rst polar year. fourteen stations ringing the arctic were established by 11 countries (norway, sweden, finland, austria, netherlands, france, germany, uk, russia, canada, us). revkin observes that the fi rst polar year marked a major change in the culture of science, which became more open, collaborative and self-critical. this book is written with the american reader in mind. for example, the arctic ocean near the north pole is described as “two miles deep— deep enough that ten empire state buildings could be stacked beneath us” (p. 11). that the book tilts decidedly toward a youthful american readership is appropriate. the american association for the advancement of science (1990) has made the point that most schoolchildren in the us are not science literate. it behooves the generation of americans about to come of age to develop a basic understanding of the causes, signs and potential impacts of climate change, as well as to improve their knowledge of other major environ188 book reviews mental problems confronting us, such as natural habitat destruction and loss of biodiversity. the scientists who are spotlighted in the north pole was here are perhaps among the fi rst people to discern the magnitude of human impacts on the natural world; our children may be among the fi rst to have to cope with these changes during their lifetimes. revkin entitled his book after a sign erected by a scientist at the north pole observatory. the joke plays on the fact that the ice supporting the temporary science camp is in constant motion. less amusing are computer simulations according to which the ice on the surface of the arctic ocean may be gone by the end of this century. as is well known in the scientifi c community, this would have radical consequences for the world. let us hope that the north pole was here— a lively paean to polar scientists—is the kind of book that engages young minds in the arctic and in science itself. reference american association for the advancement of science 1990: science for all americans. new york: oxford university press. accessed on the internet at www.project2061.org/ publications/sfaa/online/sfaatoc.htm. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <feff0041006e007600e4006e00640020006400650020006800e4007200200069006e0073007400e4006c006c006e0069006e006700610072006e00610020006e00e40072002000640075002000760069006c006c00200073006b0061007000610020005000440046002d0064006f006b0075006d0065006e00740020006d006500640020006800f6006700720065002000620069006c0064007500700070006c00f60073006e0069006e00670020006600f60072002000700072006500700072006500730073007500740073006b0072006900660074006500720020006100760020006800f600670020006b00760061006c0069007400650074002e0020005000440046002d0064006f006b0075006d0065006e00740065006e0020006b0061006e002000f600700070006e006100730020006d006500640020004100630072006f0062006100740020006f00630068002000520065006100640065007200200035002e003000200065006c006c00650072002000730065006e006100720065002e00200044006500730073006100200069006e0073007400e4006c006c006e0069006e0067006100720020006b007200e400760065007200200069006e006b006c00750064006500720069006e00670020006100760020007400650063006b0065006e0073006e006900740074002e> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice high voltage transmission lines and their effect on reindeer: a research programme in progress eigil reimers, kjetil flydal & rune stenseth we review literature on high voltage transmission lines and their effect on wild reindeer (rangifer tarandus) migration patterns and area use. we conclude that reliable knowledge is lacking on the effects of transmission lines on reindeer ecology. this condition relates to the lack of long-term monitoring of reindeer migration patterns i n relation to existing lines. it is also related to the fact that nothing is known about hearing in reindeer (or any other deer species in norway) in relation to transmission line noise, which is considered an obstacle for migrating reindeer. we then outline a research programme that includes a laboratory study to determine the audiogram in reindeer and two field studies to examine the proximate effects of transmission lines independently as well as combined with ambient environmental variables on reindeer behaviour. the audiogram in two yearling male reindeer has been determined; this part of the study will be completed this year with the determination of a corresponding audiogram in two female yearlings. the behaviour study of domestic reindeer under high voltage transmission lines was completed in september 1999. the behaviour study of wild reindeer in the area crossed by a 420kv power line will continue this year and its completion is anticipated in 2001. e. reimers & k . flydal, university of oslo, dept. of biology, box i051 blindern, n-0316 oslo, norway; r. stenseth, barnard as, division fou, gudmundsrud ggrd, n-2056 algarheim, norway. in southern norway, plans for the construction and expansion of several high voltage transmission lines (300 and 420 kv) have awakened interest in the impact of these constructions on wild reindeer (rangifer tarandus). in particular, the focus is on potential long-term effects on reindeer population dynamics and range use. according to norwegian law “the energy act” and “the plan and building act” the energy transmission authority (statnett sf) is obligated to assess the ecological consequences transmission lines may impose in areas where they travel through designated wild reindeer habitat. in accordance with this, statnett sf organized and funded a preliminary study with two objectives: 1 ) to ascertain current knowledge concerning possible conflicts between reindeer1 caribou and high voltage transmission lines; and 2) to suggest a research strategy that will elucidate the effects of high voltage transmission lines on reindeer population dynamics and range use. this paper is divided into two main parts: the first reviews the literature for what is known about the effects of transmission lines on reindeer and other species; the second outlines ongoing re search that includes a laboratory study to deter mine the audiogram in reindeer and two field studies to examine the proximate effects of transmission lines independently as well as combined with ambient environmental variables on reindeer behaviour. note: most high voltage transmission lines in norway utilize alternating current (ac) and include lines that carry more than 1 kv. the main high voltage power line system in norway consists of lines carrying 132,300 and 420 kv. high voltage transmission lines and reindeer w e anticipate three possible influences on un gulates from an established power line: 1 ) reimers et al. 2000: polar research 19(1), 75-82 75 physiological effects from electromagnetic fields; 2) disturbing noise originating from electrical discharge or wind action on lines or masts; 3) frightening visual effects from physical structures and disturbances from installation, monitoring and maintenance work on the lines. the following is based on a literature survey (reimers et al. 1998). physiological effects from electromagnetic fields animal systems have been examined under a range of electric and magnetic field intensities and for varied exposure conditions and duration. four reviews (algers & hennichs 1983; naif et al. 1989; sosialog helsedept. 1994; thommesen & tynes 1994) reveal uncertainty about which biological system or function, if any, is likely to be affected by fields. experimental data are in general consistent with theoretical considerations (thommesen & tynes 1994). they show no unambiguous biological effects from such fields that may be suspected to have health conse quences, unless field strength exceeds that neces sary to induce currents compatible with the mean level of endogenous chaotic currents. from epidemiological studies there are some indications of an increased cancer risk, particularly leukaemia, among children growing up in the vicinity of power lines (thommesen & tynes 1994). electric fields from transmission lines could affect agricultural animals in three primary ways: induced body currents and fields; fields percep tion; or shocks due to induced voltages on objects. two studies deal with transmission line electric fields and the possible effects on livestock. electric fields of the strength found beneath so0 kv transmission lines (goodwin 1975) re sulted in no visible changes in grazing, feeding and drinking habits of cattle on damp ground in electric fields up to 18 kv/m. results of this study, as well as observations of wild and domestic animals on other 500 kv transmission line rights of-way, do not indicate any aversion of animals to entering the field area. lee & reiner (1983) studied cattle behaviour near an 1100 kv prototype transmission line. the cattle showed no obvious reluctance to graze or to consume water or salt beneath the llookv line. however, when the line was periodically turned off, the use of the pasture by the cattle increased. when the line was re-energized, use of the pasture decreased. utility operating experience and overall results of research involving livestock owners indicate electric fields apparently do not notice ably affect the behaviour or health of livestock. in maximum electric field areas (i.e. 8-12 kv/m or 765 kv and 1100 kv), it is possible that some livestock species may perceive the presence of an electric field, and that in some way the electric field or noise from the lines is unpleasant to the animals. however, if no accompanying aversion or fright develops, this would not necessarily result in any outward behavioural response. on the basis of an extensive study of cattle herds exposed to 400 kv power lines for more than 15 days per season, algers & hultgren (1986) concluded that high voltage transmission lines did not influence ovary function, rut intensity or pregnancy in cows which had been kept under the line for feeding. correspondingly, in a study on possible effects from a 400 kv dc (direct current) transmission line on holstein livestock perfor mance, martin et al. (1986) recorded n o significant differences in milk production or reproductive capacity. at present we have no convincing evidence that high voltage power lines and associated electro magnetic fields detrimentally affect ungulates exposed to fields for longer or shorter periods of time, neither on their biological systems nor on their functions. as reindeer probably choose not to remain in prolonged proximity to power lines it is indeed their habit never to remain in any place for extended lengths of time we believe that physiological effects from electromagnetic fields are of limited importance for this species. disturbance from sounds originating from electrical discharge or wind on lines or masts noise in general (fletcher & busnel 1978) or noise originating from electrical discharge or wind action on lines or masts is thought to affect ungulates negatively. under climatic conditions favouring transmission line noise, animals may avoid the line corridor (ellis et al. 1978; lee & griffith 1978). in dry weather, noise from a 300 kv transmis sion line (rpd-tveiten) measured 4-26, 18-29 and 22-33db at distances of s o , 30 and 20m, respectively, from the outer line (nve 1979). in humid weather, the noise increases up to 15-30 db compared to recordings in dry weather. in a recent study, ustad (1997) showed that discharge noise from a 300 kv power line in slidalen dominated over background noise (wind noise) in the 76 high voltage transmission lines and their effect on reindeer frequency area between 2 and 16 khz in misty weather. noise from the line and the surrounding vegetation was recorded in the range 30hz to 16 khz, with corresponding sound pressure vary ing from 70 to less than 5 db. most literature deals with people and audible noise. but the hearing range in animals differs from that in man; sound that might disturb animals may be inaudible to man. audible noise measured in db with reference to hearing in man may not be the appropriate measure of noise as it is perceived by wildlife. most other mammals hear higher frequency sounds than do humans. for example, optimal hearing range of ungulates like sheep (wollack 1963), cattle and horses (heffner & heffner 1983) is from 23 hz to 42 khz, with a best sensitivity between 1 khz and 16 khz (see fig. 1). lowest threshold in db measured from -11 in cattle to 7 in horses. correspondingly, frequency values for man range from 20 hz to 18 khz, with optimal frequencies from 1 to 4 khz. although animals may be responsive to changes in the acoustic environment, they may rapidly acclimate or habituate. in a study o n sheep (ames 1978) which used heart rate and respiration rate as indicators of physiological responses, the hypoth esis of habituation to sound type and intensity was supported. on the other hand, the opposite phenomenon, so-called sensitization, is also known from beha viotiral studies. in these cases, the strength or the intensity of a response increases with repeated stimulation. this is generally the situation when bo 5 0 s $ 40 5 30 20 10 i 32 53 125 250 5w iwo 2000 4000 no00 i6oon 32000 frequency (hz) fig. i . comparison between noise level from a power line and mean capacity of hearing in some ungulates. noise measure mentq (*) have been taken for a 132 kv power line in rainy weather. the mean capacity of hearing for ungulates (.) is based on audiograms for cattle goat, horse, pig and sheep (heffner & heffner 1990). the stimulus is uncomfortable or in the animal’s experience is followed by something unpleasant. knowledge of the auditory capacities of north ern deer species (cervids) like moose (alces alces), red deer (cewus elaphus), roe deer (capreolus capreolus) and reindeer is currently lacking. disturbance from the installation, monitoring and maintenance of physical structures in an earlier review of the effects of power lines on reindeer and caribou, reimers (1984) concluded that information within this field reflects opinions rather than scientific facts. based upon the available information, reimers (1984; 1986) concluded: 1) well-documented consequences of power lines are permanent loss of grazing land covered by mast footing and temporary loss of grazing land in connection with construction. the importance for reindeer is limited. 2 ) during construction reindeer may alter their migration pattern and range use. 3) limited data indicate that semi-domestic and wild reindeer habituate to power lines shortly after their construction when the lines are not accom panied by other human activity such as road traffic, tourist tracks, settlement etc. 4) factors that may influence whether animals cross under power lines are: the topographical location of the line (e.g. in valleys, over mountain tops); whether it is located in forested or in open terrain; the location in relation to grazing, calving and rutting areas; time of the year; presence or absence of harassing insects; climatic factors that lead to corona and wind noise from the line; and the age, sex, physical and psychological condition of the animals and their earlier experience. information available from goodwin (1975), stahlecker (1975), ellis et al. (1978), lee & griffith (1978), smith et al. ( 1 986) and takatsuki (1 992) indicates that the general conclusion, above, also applies to deer (odocoileus sp.), elk (cervus canadensis), bighorn sheep (ovis cana densis), pronghorn antelope (antilocapra amer icana) and sika deer (cervus nippon). methodology in a study of elk and other deer under an energized 500 kv transmission line (goodwin 1975) included direct observations, time-lapse photography, track counts and vegeta tion analysis. typical behaviour of most deer when entering a right-of-way or control area was to reimers et al. 2000: polar reseurch 19(1), 75-82 7 1 remain motionless for a few moments at the forest edge. after this, they entered the clearing and usually began feeding. after initial wariness when entering a clearing, none of the observed deer appeared to be disturbed by the presence of the transmission line. during several days of 55 to 60db(a) noise levels, track counts did not indicate any aversion by the animals to the right of-way. data obtained through this study indicates that elk movement near the 500 kv transmission line right-of-way was not significantly different than that near other forest openings. the transmis sion line produced audible noise levels, which at times were very annoying to humans. there was no indication, however, that noise deterred elk, other deer and several other wildlife species from entering and crossing the right-of-way. it is important to emphasize that these power lines cut through forested areas. the line corridor provided an ecotone with excellent food resources and accessible hiding in the adjacent forest. the availability of both food and protection may have outweighed the possible negative effect of a power line. desert bighorn sheep were studied for six years (before, during and after construction) in relation to a 500 kv transmission line (smith et al. 1986). it was not possible for the observers to make any meaningful comments on sheep and the transmis sion line as there were few interactions between the sheep and the line. in the limited observations of smith et al., sheep crossed the line without hesitation and foraged immediately under the line without indicating any obvious distraction from the line or its associated noise. the research programme research designed to address some of the current questions relating to the effects of power lines on reindeer includes: 1 ) determination of the hearing capability (audiogram) in reindeer, including frequency range, sound level sensitivity and the lowest threshold level; 2) examination of the hearing sensitivity and threshold levels related to recordings of transmission line noise and noise from snowmobiles, aircraft and normal vehicular traffic; 3) controlled experiments with domestic reindeer fenced in under high voltage transmission lines; 4) recording and assessing the behaviour of wild reindeer in a calving area adjacent to a 420 kv transmission line in setesdal-ryfylke. the research programme started in march 1999 with taming and training of two domestic yearling reindeer males for determination of their audio gram, and the establishment of the four experi mental areas in association with the power lines. preliminary behavioural studies of wild reindeer and power lines were carried out in may 1999. the audiogram in two yearling male reindeer has now been determined and this part of the study will be completed this year with the determination of a corresponding audiogram in two yearling females. in september 1999 the behaviour study of domestic reindeer under high voltage transmission lines was completed. data processing and write-up are in progress. the behaviour study of wild reindeer in the area crossed by a 420 kv power line will continue this year and is planned to be completed in 2001. i ) hearing in reindeer: hearing range and sensitivity; audiogram determination to evaluate the effect of power line noise and noise from various human activities in connection with power line construction and maintenance, we have initiated a study to determine the audiogram in reindeer, i.e. the frequency range with corre sponding sensitivity levels. the behavioural meth ods developed should be applicable to other deer species. knowledge of the auditory capacities of deer may be important, not only in a transmission lines context, but also in an attempt to reduce automobile/train and deer accidents. in recent years, between 5000 and 6000 animals (official statistics of norway 1997) are killed annually in such collisions. deer audiograms may be determined from brainstem-evoked potentials recorded in various parts of the head in anaesthetized animals, or from conditioned behavioural responses to specific sound stimuli. we have selected the latter method, currently the most used method in determining the audiograms in mammals. testing, as described below, is well underway at the animal quarter at the university of oslo. we have now determined the audiogram for the two male yearlings and continue work with the two female yearlings. we plan to have completed determination of the audiogram for reindeer by september 2000. two male yearling reindeer have been trained to react to tones accompanied by a mild electric 78 high voltage transmission lines and their effect on reindeer shock, using a method described by heffner & heffner (1990). the thirsty animal is trained to make contact with its mouth on a waterspout in order to receive a steady trickle of water. tones are presented at random intervals and are followed by a mild electric shock delivered through the spout. by breaking contact with the spout during tone presentation, the animal avoids the shock and indicates that it has heard the tone. testing occurs, according to a procedure established by heffner & heffner (1995), in a double-walled sound chamber (2.4 x 3.6 x 2.4 m), the walls and ceiling of which have been lined with sound absorbing panels to minimize outside noise and sound reflection. an adjacent room houses the test equipment. during testing the animal is confined in a rectangular cage with a loudspeaker, 1 rn in front of the cage at the level of the animal’s ears. the mildness of the electrical shock is empirically verified by observing that none of the animals ever develop fear of the waterspout and return to it without hesitation after receiving a shock. to receive feedback for successful avoid ance, a light in the test chamber is momentarily flashed on each time a shock is delivered. auditory threshold is determined for each frequency by reducing the intensity of the tone in 5 db steps until the animal can no longer distinguish tone trials from silent trials. threshold is defined as the lowest intensity yielding a performance of 0.50 (performance = hit rate [hit rate x false alarm rate]) (heffner & heffner 1995). the use of pure tone stimulation is necessary when training animals to obtain their audiogram. pure tones will in most cases only alert an animal and not cause any fright or flight reaction. other sounds with many sound frequency components, or noise, may however, give a spontaneous fright reaction. it is therefore necessary to apply such noise in the tests as indicated in 2), below. 2 ) hearing in reindeer: hearing range and sensitivity of noise related to transmission lines and human activity transmission line noise (wind noise and electrical discharge) and traffic sounds (aircraft, snow mobiles, vehicular traffic) will be recorded and analysed for frequency level and intensity. noise levels are related to the audiogram of reindeer to reveal their disturbing potential to the animals. noise recordings will be played in tests during august 2000 with our experimental female rein deer, to determine the relevance of such a testing procedure to evaluate possible behavioural effects of noise. 3 ) behaviour of domestic reindeer under a high voltage transmission line the reindeer’s sensory perception of a power line is potentially a combination of stimuli from the power line alone and these same stimuli combined with environmental variables. relevant environ mental variables (weather factors, food distribu tion and availability, forms of harassment and combinations of these variables) can in turn strengthen or weaken the effects of the power line. the objective of this experiment, which took place in august-september 1999, was to test the reactions of reindeer toward power lines under different environmental variables and sensory stimuli (sight, sound, electric fields and general perception). t h e experimental area was established adjacent to the two high voltage transmission lines (132 kv and 300 kv) along slidalsvegen in north otta dalen, norway, where natural reindeer habitat and forage exist. the experiments were carried out in four oblong pens (fig. 2 ) with two treatment pens located beneath the power lines, and two control pens in an adjacent area that was not influenced by the lines. the four 50 x 400 m pens were similar in size, shape, topography, vegetation cover etc. during august and september 1999 three 1 % year old domestic female reindeer were released in each pen. through the scan method (altmann 1974) we recorded manually the activity of the 12 reindeer in the four pens every 10 minutes during the daylight hours. the information recorded included location of the individual animals in the pens and their activities, such as standing, feeding still, feeding slow walk, running, lying head down, lying head up. every 20 minutes the activity of one focal animal (altmann 1974) was recorded for 5 minutes, with the time spent in each activity noted. data on wind speed and direction, precipitation, temperature and humidity were obtained from a portable weather station (fig. 2). the combined recordings enabled us to determine the effects of important weather and environmental variables and test for their independent or combined effects with a power line in the reindeer’s ambient environment. replication of each treatment pen gave the opportunity to sort out the effect of individual variation between animals. by compar reimers et al. 2000: polar research 19(1), 75-82 79 ing treatment pen and control pen the effect of the power line could be separated from the effect of the pen itself. replication was increased by introducing 12 new animals after 2 weeks, and by a crossover between control animals and treatment animals. the animals had access to water in buckets located at two places (at 50 m and 350 m) in the pens. 4 ) video monitoring behaviour of the reindeer in the four pens based on a monitoring concept developed by one of us (stenseth), we have designed a monitoring approach using video as a tool for acquiring vital information about the behaviour of the reindeer in the four pens (fig. 3). an astraguard video motion analysing system was connected to eight video cameras programmed to react to prescribed situations, while continuously analysing the scenes. the astraguard is connected to other equipment, like video transmission, via cables called the i/o system. if astraguard spots reindeer on channel 2, it will accordingly raise the voltage level on cable 2 , telling the video transmission to select camera 2, and send pictures back to the user from this camera. astraguard will store pictures of what it detects, even if it for some reason fails to alert the user immediately (communication lines might be temporarily out of service). one can also trigger a “trip” around the camera’s view when detection occurs, to give an overview of what goes on. for outdoor applications, all of the electronic fig. 2 . the study area in north ottadalen, norway, showing the location of the two experimental pens (exp. 1 & 2) under the power lines (132 kv and 300 kv), the two control pens (con 1 & 2 ) , the weather station (w) and the research facility ( r s ) . equipment may be installed in a hardened water proof device called scout (self-contained observation unit). in our experiment, the astraguard was pro grammed to divide the visible field of view into 3 zones at 100, 200 and 300+ m in each pen. for each zone we prescribed areas of interest during the tests, and astraguard returned pictures from 1 i i f i g . 3. the main components of an astragard installation are: sensors (a), instrument unit with instruments (b), communica tion package (c), power supply and batteries (d). the cameras are connected to a video distribution amplifier which splits the video signals between the astraguard video detection unit and the video transmission system. astraguard is a computer, which ‘‘looks’’ at the video cameras view continually; when movement that fits the pattern or programmed set-up takes place, it is triggered to react in the fashion we choose. the scout system (self-contained observation unit) houses the equipment and connects to a suitable number of cameras. the astraguard computer in scout, programmed to react to a prescribed situation, will continuously analyse the scenes. this reaction can be programmed as any of a number of possible actions, such as taking pictures, sending pictures to a remote location, activating a microphone or tape recorder etc. 80 high voltage transmission lines and their effect on reindeer the zones whenever reindeer crossed the zone boundaries. due to budgetary limits we only got the cameras in one of the experimental pens (with power lines) operative. data from these two cameras compared with simultaneous manually recording of reindeer activity showed that the cameras recorded precisely the animals shifting use of the established zones. we eventually got the other cameras to work, but n o data were stored from the other pens. recordings of animals that crossed in either direction between zone 1 and 2 and zone 2 and 3 + in this pen were logged with image, date and time and stored in the database for later retrieval and processing. as the purpose of this experiment was to test the astraguard recording method as an alternative to manual recording of behaviour, we conclude that this innovative system, which minimizes the possible disturbing effects of observers, opens up exciting possibilities for the study of animal behaviour. relation to transmission line noise, which may be an obstacle for migrating reindeer. it is important to fill these gaps because of actual and possible conflicts between reindeer (both semi-domestic and wild) and existing as well as planned power lines. these questions are currently addressed in an ongoing research programme with several components, the results of which will be analysed and published within the next two years. acknowledgements. we thank p. s. b0ving for assistance in the literature survey, and j. h. l’abke-lund, k. nybak and p. enger for scientific input during the planning process. this study was supported financially by the rein-project under the effekt-programme (norwegian research council contract no. 125127/212), trygve gotaas fond and stiftelsen thomas fearnley, heddy og nils astrup. references algers, b. & hennichs, k. 1983: biological effects of electromagnectic fields on vertebrates. a review. vet. res. commun. 6,265-279. algers, b. & hultgren, j. 1986: hur pdverkas husdjuren av kraftledninpar? (how are domestic animals affected bv 5 ) behaviour of wild r e i d e e r in an ~ e a crossed y by a 420 kv power line in setesdal-ryfilke power lines?). veterinarmedicin 2. swedish university of to our knowledge, no observational report exists that records and evaluates reindeer (or other animal species) behaviour upon approach to, or crossing under, a transmission line. in view of the plans for new transmission lines and reinforcement of current lines, we believe that such information is urgently needed. to address this knowledge gap, we established in 1999 an observation area south of botsvatn in setesdal-ryfylke, norway, where a 420 kv power line crosses through a major calving area. reindeer behaviour under and adjacent to the power line was recorded manually, in a set-up similar to the one described under 3), and on video during may. the fieldwork in this area continues in may-june 2000 and is expected to be completed at the same time next year. conclusion reliable knowledge is lacking on the effects of transmission lines on reindeer ecology. this condition relates to the lack of long-term monitor ing of reindeer migration patterns in relation to existing lines. it is also related to the fact that no knowledge exists regarding hearing in reindeer in agriculture. altmann, j. 1974: observational study of behaviour: sampling methods. behaviour 49, 227-267. ames, d. r. 1978: physiological responses to auditory stimuli. in j. l. fletcher & r. g. busnel (eds.): effects of noise on wildlife. pp. 23-46. london: academic press. ellis, d. h., goodwin, j. g., jr. &hunt, j. r. 1978: wildlife and electric power transmission. in j. l. fletcher & r. g. busnel (eds.): effects of noise on wildlife. pp. 81-104. london: academic press. fletcher, j. l. & busnel, r. g. (eds.) 1978: effects of noise on wildlife. london: academic press. goodwin, 1. g., jr. 1975: big game movement near a 500 kv transmission line in northern idaho. prepared for bonneville power administration, engineering and construction divi sion, portland, or. heffner, r. s. & heffner, h. e. 1983: hearing in large mammals: horses (equus caballus) and cattle (bos raurus). behav. neurosci. 97, 299-309. heffner, r. s . & heffner, h. e. 1990: hearing in domestic pigs (sus scrofa) and goats (capra hircus). hearing res. 48, 231 240. heffner, r. s. & heffner, h. e. 1995: conditioned avoidance. in r. j. klump et al. (eds.): methods in comparative psycho acoustics. pp. 79-93. basel: birkhauser verlag. lee, j., jr. & griffith, d. b. 1978: transmission line audible noise and wildlife. in j. l. fletcher & r. g. busnel (eds.): effects of noise on wildlife. pp. 105-168. london: academic press. lee, j. m, jr. & reiner, g. l. 1983: transmission line electric fields and the possible effects on livestock and honeybees. transactions of the asae (am. soc. agric. eng.) 26, 279 286. martin, f. b., bender, a., steuernagel, g., robinson, r. a., reimers e t al. 2000: polar r e s e a r c h 19(1), 75-82 8 1 revsbech, r., sorensen, d. k . , williamson, n. & williams, a. 1986: epidemiologic study of holstein dairy cow performance and reproduction near a high-voltage-direct current powerline. j . toxicol. environ. health 19, 303-324. nair, i., morgan, m. g. & florig, h. k. 1989: biological effects of power frequency electric and magnetic fields. ota-bp-e 53. us congress, office of technology assessment. wash ington, d.c.: us government printing office. nve (norges vassdragsog energidirektoratnorway 's water resources and energy directorate) 1979: st@y og statisk induksjon f r a elektriske anlegg. (noise and static induction from electric installations.) norges vassdragsog elektrisi tetsvesen. official statistics of norway 1997: hunting statistics. oslo: statistics norway. reimers, e. 1984: virkninger av menneskelig aktivitet p b rein or caribou. en lieraturstudie. (effects of human activity on reindeer and caribou. a literature study.) vn rapp. 9. natur og landskapsavdelingen, norges vassdragsog energi direktorat (nve) (nature and environment dept., norwegian water resources and energy directorate). reimers, e. 1986: virkninger av menneskelig aktivitet pii rein og caribou. en litteraturstudie. (effects of human activiry on reindeer and caribou. a literature study.) kraft og mi& 12. naturog landskapsavdelingen, norges vassdragsog energidirektorat (nve) (nature and environment dept., norwegian water resources and energy directorate). reimers, e., boving, p. s., coleman, j . e. & enger, p. s . 1997: study proposal f u r determining effects of high voltage wansmission line on behavioral ecology of wild reindeer. biological institute, university of oslo. smith, e. l., gaud, w. s., miller, g. d. & cochran, m. h . 1986: studies of desert bighorn sheep (ovis canadensis mexicana) in western arizona. impacts of the palo verde to devers 500 kv transmission line. final reportj vol. 2. prepared for southern california edison co. and arizona public service c o . sosialog helsedept. (social and health dept.) 1994: har tavfrekvente elektriske og magnetiske felt noen helsemessig betydning? (do low frequency electrical and magnetic fields have any impact on health?) sosialog helsedept. rapp. may. norway. stahlecker, d. w. 1975: impacts o f a 230 kvtransmission line in great plains wildlife. m.sci. thesis. colorado state university, fort collins. takatsuki, s. 1992: a case study on the effects of a transmission-line corridor o n sika deer habitat use at the foothills of mt goyo, northern honshu, japan. ecol. res. 7, 141-146. thommesen, g. & tynnes, t. 1994: statiske og lavfrekvente elektriske og magnetiske felt. biologiske effekter og yrkeshygienisk betydning. (static and low frequency electric and magnetic fields: biological effects and significance in occupational health.) strcilevern rapp. 1994: i . bsteris: statens strilevern (norwegian radiation protection author ity). ustad, a. 1997: akustiske stpym81inger av 300-kv ledningen slcidalen 11. (acoustic noise measurements of the 300 kv line slcidalen i i . ) sintef tele og data notat, september. norway. wollack, c. h. 1963: the auditory acuity of the sheep (ovis a r k s ) . j . aud. res. 3, 121-132. 82 high voltage transmission lines and their effect on reindeer chaulk.indd 121chaulk et al. 2004: polar research 23(2), 121–130 understanding regional and annual variation in the breeding ecology of organisms is important for conservation and management purposes. variable expression of ecological characteristics often occurs in response to change in the environment where organisms live. breeding ecology can be infl uenced by biophysical factors at differing temporal and spatial scales (scott et al. 2002). aspects of avian ecology such as nest density, clutch size, and egg volume can be infl uenced by population dynamics, population genetics, habitat quality, and/or food availability (lack 1967; ryder 1970; robertson et al. 2001; hario & selin 2002). furthermore some components of breeding ecology may be prone or resistant to annual and/or regional fl uctuations in the biophysical environment (avise & hamrick 1996; erikstad, tveraa et al. 1998; bregnballe 2002; hario & selin 2002). common eiders (somateria mollissima) are an important species for many northern peoples, as a source of meat, eggs and down. these birds exhibit substantial variation in the timing of nesting, nesting density, clutch size and other aspects of their breeding ecology (goudie et al. 2000; robertson et al. 2001; chaulk et al. in press). underregional and annual variability in common eider nesting ecology in labrador keith g. chaulk, gregory j. robertson, & william a. montevecchi nesting densities are often used to estimate breeding population size and with other measures of reproductive performance can be useful indicators of population status. these aspects of breeding biology often show considerable spatial and temporal variation. between 2000 and 2003, we surveyed nesting common eiders (somateria mollissima) on 172 islands in three archipelagos (nain, hopedale, rigolet) on the labrador coast. rigolet was the largest archipelago (2834 km2) followed by nain then hopedale, and island density varied inversely with archipelago size. overall means were: nest density 52.0 ± 141.9 (sd) nests/ha; nest initiation 12 june ± 12 days; clutch size 3.7 ± 1.2 eggs/nest; egg volume 98.8 ± 10.4 cm3; and clutch volume 392.3 ± 135.0 cm3. rigolet had the highest average egg volumes and nest densities, the highest single island nest density of 1053 nests/ha, and the earliest average nest initiation date. we found signifi cant differences in nest densities among archipelagos and across years; signifi cant archipelago and year interactions were detected for nest initiation date and clutch size. signifi cant differences were found among individual islands for all response variables except egg volume. for egg volume, within-archipelago island differences were not signifi cant, but between-archipelago differences were signifi cant. thus egg volume may be a useful diagnostic to identify population affi liation. k. g. chaulk, labrador inuit association, box 382 station “c”, goose bay, labrador, nl, canada a0p 1c0, kchaulk@nunatsiavut.com; g. j. robertson, canadian wildlife service, 6 bruce street, mount pearl, newfoundland, nl, canada a1n 4t3; w. a. montevecchi, department of psychology, memorial university of newfoundland, st. john’s, newfoundland, nl, canada a1b 3x9. 122 regional and annual variability in eider nesting ecology standing patterns of annual and regional variation in eider breeding performance can be very important for management and conservation purposes. early nest initiation dates and large clutch sizes are generally indicative of favourable breeding conditions, while nesting densities are often used to estimate breeding population size. unfortunately most eider research is limited in spatial and/or temporal scope, and the rare papers that contain multi-year and/or multi-site comparisons, are generally from temperate climes in northern europe (milne 1974; swennen 1983; coulson 1984, 1999; hario selin 1988; bregnballe 2002; hanssen et al. 2003). the goal of this paper was to examine annual and regional variation of common eider nesting ecology at three distinct sites on the mid-labrador coast, a subarctic region, over a four-year period (2000 to 2003). in this paper, we investigate nest density, nest initiation, clutch size, egg and clutch volume. in general we expected both regional and annual variation in most nesting characters, as these traits have been shown to vary in eiders. of greater interest was whether annual patterns of variation were maintained across regions, or whether traits varied independently within regions across the years. study area archipelagos near the communities of nain, hopedale and rigolet were surveyed from 2000 to 2003 (fig. 1). the extent of each archipelago was determined by calculating a minimum convex polygon (mohr 1947) containing all islands that were completely searched. the total geographic area of the three archipelagos was estimated to be 4785 km2, and contained approximately of 1600 islands (table 1). the archipelago adjacent to rigolet covered the largest geographic area while the archipelago adjacent to hopedale was the smallest (table 1). overall the average size of islands within the three archipelagos was 30.1 ha ± 288.8 (1 sd); on average the largest islands were found in the rigolet archipelago (table 1). the greatest island density occurred in the hopedale archipelago (0.90 islands/km2) foltable 1. location, island characteristics, sampling intensity and sampling dates of archipelagos in labrador where data were collected on nesting ecology of common eiders (somateria mollissima), 2000–2003. nain hopedale rigolet all study area location mean latitude (ºn) 56.36 55.33 54.18 mean longitude (ºw) 61.06 59.81 57.41 study area size (km2) 1151 800 2834 4785 study area perimeter (km) 145 128 278 551 n (islands) in study area 497 720 335 1552 island density (islands/km2) 0.43 0.90 0.12 0.32 archipelago island size mean ± 1 sd (ha) 33 ± 318 20 ± 194 47 ± 394 30 ± 289 range (ha) 0.01 6903 0.02 3875 0.02 5204 0.01 6903 size sampled islands mean ± 1 sd (ha) 1.3 ± 1.5 1.6 ± 2.6 4.1 ± 10.2 2.3 ± 6.0 island sampling scheme no. one year only 13 33 17 63 no. two years only 11 19 15 45 no. three years only 10 14 12 36 no. all four years 8 13 7 28 survey dates 2000 3 9 july 28 30 june 20 26 june 20 june 9 july survey dates 2001 5 19 july 4 17 july 18 27 june 18 june 19 july survey dates 2002 13 22 july 3 17 july 17 22 june 17 june 22 july survey dates 2003 11 13 july 3 7 july 14 20 june 14 june 13 july 123chaulk et al. 2004: polar research 23(2), 121–130 lowed by nain then rigolet (table 1). all archipelagos shared similar environmental characteristics such as a northern maritime climate, vegetation composed primarily of mosses, lichens, forbes, grasses, and sedges. the archipelagos were typically comprised of barren islands with sparse vegetation and very limited nesting cover. islands in the rigolet area had denser and taller ground vegetation, and on some islands woodier cover, including stunted black spruce (picea mariana). all three archipelagos are classifi ed as coastal barrens (lopoukhine et al. 1978), are considered to have a high boreal ecoclimate (meades 1990) and a low arctic oceanographic regime (nettleship & evans 1985). on the central and northern labrador coast the concept of discrete archipelagos is somewhat misleading, as the island complex along this coast is for the most part continuous. the island complexes, hereafter referred to as archipelagos, selected for study were typical of this portion of the labrador coast. methods from 2000 to 2003 we surveyed three archipelagos (nain, hopedale, rigolet) for nesting eiders. islands were selected for study on the basis of random sampling. in all cases we limited our searches to islands that were estimated to be smaller than 30 ha. analysis of the spatial distribution of our data set show that our samples were spatially random within the subset of islands that were less than 30 ha within each archipelago (k. g. chaulk unpublished data). ground surveys were conducted using standard search methods employed by the canadian wildlife service (nettleship 1980) and other researchers (falardeau et al. 2003; merkel 2004; chaulk et al. in press); these consisted of two to four people walking linearly over the islands searching for signs of eider nesting. islands in the three archipelagos were for the most part barren with limited nest-cover; hens and unattended nests were easily detected. archipelagos were searched at approximately the same time each of the four years (table 1). for the most part the senior author conducted all surveys, the exception being nain and hopedale in 2001 and 2002, where the senior author initiated the surveys but the fi eld crew completed them. for each common eider nest observed, information was recorded on apparent clutch size, nest age, and nest status. nests were classed as follows: incubating – current season nest containing fig. 1.: general location of archipelagos surveyed between 2000 and 2003 on the labrador coast. 124 regional and annual variability in eider nesting ecology eggs; hatching – at least one chick was breaking its shell; hatched – at least one chick was completely out of its shell; depredated – broken and bloody eggs were present in or immediately adjacent to the nest; and unknown – nest was in disrepair with no eggs or signs of depredation. the incubation period was assumed to be 24 to 26 days (goudie et al. 2000), with incubation generally commencing after the laying of the penultimate egg (hanssen et al. 2002). candling was used to age the eggs (weller 1956) and to calculate nest initiation we added the number of eggs to the egg age and we subtracted this number plus one from the survey date. nests with more than six eggs were not aged. apparent clutch sizes were calculated using nests classifi ed as incubating; nests with more than six eggs are generally considered dump nests produced by two or more females (swennen 1983; robertson 1995) and were omitted from the analysis. due to lack of data, nest initiation dates were not calculated for the 2001 breeding year. with respect to egg size measurements we randomly selected a subset of previously surveyed islands, and on these we randomly selected nests and eggs for further investigation. each randomly selected egg was then measured using vernier calipers: egg length was measured from pole to pole, and width was measured at the widest part of the egg; all measurements were recorded in mm. egg volume was calculated based on the formula presented by guild (1974) and robertson et al. (2001); clutch volume was estimated only for nests for which we had data on egg volume and clutch size. clutch volume was estimated as clutch size multiplied by the estimated egg volume for a given nest. island nest densities were calculated using islands that were completely searched. island sizes were derived from digital 1:50000 base maps for the labrador coast. geodetic coordinates are reported as latitude and longitude, decimal degrees, north american datum 1983. nest density, nest initiation, and clutch size were analysed using a general linear model, with the year, archipelago and its interaction as fi xed factors. island, nested within archipelago, was also included as a random factor to control for multiple measurements of islands across years. egg volumes and clutch volumes were analysed with one-way anova, with archipelago as a fi xed factor and island, nested within archipelago, as a random factor. critical alpha was set at 0.05 for all tests, which were all two-tailed. results we sampled 172 islands in the three archipelagos with the greatest island sampling effort expended in hopedale (table 1). the average size of sampled islands was 2.3 ± 6.0 ha (table 1). on the islands that were completely searched we counted 10 962 eider nests and these contained 35 401 eggs. overall, on average there were 52 nests/ha or 172 eggs/ha (table 2). the highest nest counts were observed in rigolet; one island had 654 nests, and another island, 0.18 ha in size, had the equivalent of 1053 nests/ha. for island nest-density both archipelago and year were signifi cant factors, although they did not show statistically signifi cant interaction (table 3). there appeared to be greater between-archipelago variation than between-year variation in nest density (fig. 2). the overall average nest initiation date was 12 june, the earliest average nest initiation dates occurred in the south at rigolet (3 june) and the latest in the north at nain (23 june) (fig. 3). however, we detected a signifi cant interaction between archipelago and year for nest initiation date (table 3, fig. 4). the overall average clutch size was 3.7 ± 1.2 eggs/nest (table 2). the largest average clutch size was observed in hopedale at 3.8 ± 1.2 eggs, followed by rigolet at 3.7 ± 1.2 eggs, and nain at 3.6 ± 1.2 eggs; howevtable 2. mean ( ± 1 sd) and ranges of nesting traits of common eiders breeding in labrador, 2000–2003. period n mean nest density (nests/ha) 2000–03 331 52.0 ± 141.9 (range = 0 1053) nest initiation 2000, 02–03 272 12 june ± 12 d (range = 21 may to 9 july) clutch size 2000–03 10 137 3.7 ± 1.2 (range = 0 6) egg volume (cm3) 2003 415 98.8 ± 10.4 (range = 61.0 160.0) clutch volume (cm3) 2003 415 392.3 ± 135 (range = 77.2 1008.4) 125chaulk et al. 2004: polar research 23(2), 121–130 fig. 2.: interval plot of mean nest density (nests/ha) by archipelago and year with 95 % ci. horizontal line is equal to the overall mean. fig. 3.: interaction plot of mean nest initiation (day of year) by archipelago and year. horizontal line is equal to the overall mean. fig. 4.: interaction plot of mean clutch size (eggs/nest) by archipelago and year. horizontal line is equal to the overall mean. 126 regional and annual variability in eider nesting ecology er, we detected a signifi cant interaction between archipelago and year for clutch size (table 3, fig. 4). egg volume varied signifi cantly among archipelagoes but not across individual islands (table 3). the largest egg volume was observed in rigolet and the smallest in nain (fig. 5). the largest clutch volume was observed in hopedale (table 2, fig. 5) although the differences among archipelagos were not signifi cant (table 3). discussion the highest nest density that we observed occurred in rigolet (1053 nest/ha). this observation was made on a small island approximately 0.18 ha, and is high relative to nest densities reported elsewhere. for example, s. m. borealis typically nest at low nest densities (0.8 to 4.5 nests/ha; cooch 1986), though there are some exceptions, such as east bay, southampton island (abraham & finney 1986). nest densities for s. m. dresseri in the st. lawrence river averaged 3 nests/ha, but reached as high as 741.5 nests/ha (chapdelaine et al. 1986). nesting densities are probably infl uenced by numerous interacting local factors, including—but not limited to—available nesting islands and brood rearing areas, predators, disturbance, and overall population size. previously, we also observed signifi cant differences in nest densities among archipelagos across a larger geographic range in labrador, but were not able to examine annual variation (chaulk et al. in press). the present analysis suggests that annual variation is important, and suggests increasing nest densities over the 2000–2003 study period. nest initiation spring ice break-up was late in both the hopedale and nain archipelagos during 2002. we found a signifi cant interaction between archipelago and year with respect to nest initiation date, with rigolet in the south showing relatively consistent timing, and the two northern archipelagos showing greater annual variation. earlier, we documented that nest initiation dates in labrador were positively related to lattable 3. summary of general linear model analysis by variable for nesting characteristics of common eiders breeding in labrador, 2000–2003. variable model fi tr2-adjusted ( % ) factors df f p nest density 90.3 year 3 4.2 < 0.01 archipelago 2 3.9 0.02 year–archipelago interaction 6 1.1 0.36 island nested in archipelago 165 17.9 < 0.01 nest initiation 72.6 year 2 42.7 < 0.01 archipelago 2 62.1 < 0.01 year–archipelago interaction 4 7.1 < 0.01 island nested in archipelago 63 2.4 < 0.01 clutch size 6.6 year 3 3.5 < 0.01 archipelago 2 9.4 0.01 year–archipelago interaction 6 10.1 < 0.01 island nested in archipelago 116 4.7 < 0.01 egg volume 6.1 archipelago 3 5.5 < 0.01 island nested in archipelago 43 1.1 0.27 clutch volume 11.5 archipelago 3 0.8 0.44 island nested in archipelago 43 2.0 < 0.01 127chaulk et al. 2004: polar research 23(2), 121–130 itude, but we were not able to test year effects (chaulk et al. in press). this latitudinal pattern still holds over multiple years, but there can be substantial between-year variation in the timing of nest initiation. this highlights the importance of multi-year studies, especially for those aspects of breeding ecology that can be easily infl uenced by biophysical factors, such as sea ice break-up in the spring (laurila & hario 1988; goudie et al. 2000). given that we found an interaction between archipelago and year in nest initiation date, it is likely that nest initiation date is infl uenced by ice conditions at the local level. it is important to recognize that common eider nest initiation can be infl uenced by annual variation in the timing of spring break-up. this could mean that common eiders are a potentially good species for monitoring the effects of climate change in this region of north america, but our results show that more than one site would need to be monitored. clutch size clutch size is often used as a comparative measure between different populations (lewis 1939; milne 1974; swennen 1983; coulson 1984; robertson et al. 2001; bregnballe 2002; chaulk et al. in press). common eider clutch size is infl uenced by female body condition, food availability, disease, body parasites, severity of winter, timing of spring, predation and nest parasitism (rohwer 1992, erikstad, bustnes et al. 1993). some researchers have suggested that average clutch size may increase during population growth (hario & selin 1988), whereas other have found no such trend (swennen 2002). our analysis revealed a signifi cant interaction of archipelago and year on clutch size, indicating that any annual patterns were not matched across regions. however, our model had a low r2 value; therefore a signifi cant amount of variability remains unexplained by either archipelago, year or their interaction. interestingly, bregn balle (2002) did fi nd that clutch size varied across years in a similar way across fi ve colonies in denmark. at a larger spatial scale, coulson (1999) found that clutch size varied independently across years between scottish and dutch colonies. clearly, the geographic scale of the analysis appears to be important. previously, we found signifi cant archipelago differences in clutch size but this fi nding was based on analysis of one year of data (chaulk et al. in press). annual and regional variation in clutch size is not surprising. our new fi ndings suggest that average clutch size varies by archipelago and year at the scale of coastal labrador, and we do not recommend the use of single measures (i.e., one archipelago and/ or year) of clutch size as a basis to assess population productivity. instead long-term measurements over several archipelagos are needed for robust comparisons between different populations. fig. 5.: interval plot of mean egg and clutch volume (cm3) by archipelago with 95 % ci. horizontal lines are equal to the overall means. 128 regional and annual variability in eider nesting ecology egg and clutch volume some studies have shown that annual variation in eider egg volume is limited (swennen & van der meer 1992; robertson 1995; laurila & hario 1998; hanssen et al. 2002). as such, egg volume may hold value as a comparative measure between populations at large geographic scales (robertson et al. 2001). in 2003, egg volume differed significantly by archipelago, but not by island, whereas clutch volume differed by island but not by archipelago. clutch volume is largely infl uenced by clutch size, and likely has limited value as a comparative measure between archipelagos (see above). our data support the idea that average egg volume has merit to assess population structure at moderate geographic scales (i.e., 100s of km). but with only one year of data and low r2 values for our egg and clutch volume models additional data are required to assess spatial and temporal interactions. using values presented in goudie et al. (2000) we calculated average egg volumes for two subspecies of common eiders in north america (borealis = 96.4 ± 4.4 cm3, range = 93.8 102.8; dresseri = 108.0 ± 5.5, range = 100.6 115.8). based on an examination of these values it appears that egg volumes from nain were most similar to those of borealis, while the values for hopedale and rigolet were on the high end for borealis and on the low end for dresseri. this pattern is likely the result of intergradation between borealis and dresseri in the zone of overlap that is considered to occur in both hopedale and rigolet (mendall 1980; chaulk et al. in press). egg volume followed a latitudinal pattern with eiders from rigolet in the south having the largest egg volumes and eiders from nain in the north having the smallest. finally, we feel the need to comment on our sampling scheme, as the average size of sampled islands was signifi cantly lower than the average size of islands in each archipelago. we actively excluded islands larger than 30 ha from our surveys. we did this for logistical reasons. large islands require signifi cant effort to search, so instead we focused on smaller islands that could be easily censused by small fi eld crews over restricted time periods. goudie et al. (2000) reported that common eiders preferred nesting on islands < 75 100 ha. other researchers have used island size thresholds to help identify islands for investigation during eider breeding research (nakashima & murray 1988; robertson & gilchrist 1998; merkel 2004) or focused on small islands during breeding surveys (korschgen 1977; götmark & åhlund 1984). it is possible that omitting islands > 30 ha has impacted our results, most likely with respect to our estimates of nest density and percentage of occupied islands. in addition, larger islands might have greater vegetative coverage, and cover has been shown to increase nest success (choate 1967; milne 1974; schmutz et al. 1983), and nest success could in turn impact some of the breeding characteristics that we discuss in this paper. since we lack data from islands > 30 ha we have no way of knowing the magnitude or direction of these differences. however, our personal observations and discussions with local aboriginal people support the idea that eiders breeding on the mid-labrador coast rarely use large islands (> 30 ha) for nesting. we recognize that the spatial structuring and the biophysical characteristics of eider breeding islands are important, but these variables are beyond the scope of this paper. we hope to investigate habitat requirements of common eiders breeding in labrador in future research. conclusions to summarize our fi ndings, when annual effects were detected, they often interacted with regional effects. based on the inter-annual and interregional variation, as well as their interactions, long-term surveys over wide geographic regions are needed for comprehensive understanding of population dynamics and responses to environmental changes. such understanding is needed for sound management decisions. for example, large clutch sizes and early breeding could lead to a liberalization of hunting regulations given the expected large number of young birds in the fall fl ight. conversely, reduced clutches and late breeding might be used as rationale to reduce harvest quotas and limit hunting seasons. however, if only one site is assessed, our results suggest that these indicators of breeding conditions would not be representative for an entire breeding range. finally, egg volume does not appear to vary between islands at small geographic scales (i.e., within an archipelago), but does vary at moderate geographic scales (i.e., 100s of km) and could hold promise as an indicator of population genetic differences (robertson et al. 2001). 129chaulk et al. 2004: polar research 23(2), 121–130 acknowledgements.—special thanks to b. turner (canadian wildlife service); n. anderson, k. dicker, d. pottle, w. wolfrey (fisheries and oceans canada); j. rowell, b. anderson, w. hunter, i. winters, e. merkuratsuk, d. wolfrey (labrador inuit association). special thanks also go to shawn broomfi eld for help in preparing the data for analysis. the labrador inuit association, the canadian wildlife service, the northern ecosystem initiative, the northern scientifi c training program, memorial university of newfoundland, and inco provided funding for this study. we also thank a. mosbech and s. hanssen for their very helpful comments. references abraham, k. f. & finney, g. h. 1986: eiders of the eastern canadian arctic. in a. reed (ed.): eider ducks in canada. can. wildl. serv. rep. ser. 47, 55–73. avise, j. c. & hamrick, j. l. (eds.) 1996: conservation genetics. london: chapman & hall. bregnballe, t. 2002: clutch size in six danish common eider somateria mollissima colonies: variation in egg production. in h. noer & g. nehls (eds.): population processes in the common eider somateria mollissima. danish review of game biology 16. rønde, denmark. chapdelaine, g., dupuis, p. & reed, a. 1986: distribution, abundance et fl uctuations des populations d’eider à duvet dans l’estuaire et le golfe du saint-laurent. (distribution, abundance, and fl uctuation of eider populations in the st. lawrence estuary and gulf). in a. reed (ed.): eider ducks in canada. can. wildl. serv. rep. ser. 47, 6–11. chaulk, k. g., robertson, g. j., montevecchi, w. a. & ryan, p. c. in press: aspects of common eider nesting ecology in labrador. arctic. choate, j. s. 1967: factors infl uencing nesting success of eiders in penobscot bay, maine. j. wildl. manage. 31, 769–777. cooch, f. g. 1986: the numbers of nesting northern eiders on the west foxe islands, nwt, in 1956 and 1976. in a. reed (ed.): eider ducks in canada. can. wildl. serv. rep. ser. 47, 114-118. coulson, j. c. 1984: the population dynamics of the eider duck somateria mollissima and evidence of extensive nonbreeding by adult ducks. ibis 126, 525–543. coulson, j. c. 1999: variation in clutch size of the common eider: a study based on 41 breeding seasons on coquet island, northumberland, england. waterbirds 22, 225–238. erikstad, k. e., bustnes, j. o. & moum, t. 1993: clutch-size determination in precocial birds: a study of the common eider. auk 110, 623–628. erikstad, k. e., tveraa, t. & bustnes, j. o. 1998: signfi cance of intraclutch egg-size variation in common eider: the role of egg size and quality of ducklings. j. avian biol. 29, 3–9. falardeau, g., rail, j.-f., gilliland, s. & savard, j.-p. l. 2003: breeding survey of common eiders along the west coast of ungava bay, in summer 2000, and a supplement on other nesting aquatic birds. can. wildl. serv. tech. rep. ser. no. 405. götmark, f. & åhlund, m. 1984: do fi eld observers attract nest predators and infl uence nesting success of common eiders. j. wildl. manage. 48, 381–387. goudie, r. i., robertson, g. j. & reed, a. 2000: common eider (somateria mollissima). the birds of north america (a. poole & f. gill, eds.) 546. philadelphia, the birds of north america inc. guild, b. l. 1974: the breeding biology of the hudson bay eider at la pérouse bay, manitoba. m.sc. thesis. wright state university, dayton, oh. hanssen, s. a., folstad, i. & erikstad, k. e. 2002: incubation start and egg size in relation to body reserves in the common eider. behav. ecol. sociobiol. 52, 282–288. hanssen, s. a., folstad, i. & erikstad, k. e. 2003: reduced immunocompetence and cost of reproduction in common eiders. oecologia 136, 457–464. hario, m. & selin, k. 1988: thirty-year trends in an eider population: timing of breeding, clutch size and nest preferences. finn. game res. 45, 3–10. hario, m. & selin, k. 2002: cohort-specifi c differences in reproductive output in a declining common eider somateria mollissima population. in h. noer & g. nehls (eds.): population processes in the common eider somateria mollissima. danish review of game biology 16. rønde, denmark. korschgen, c. e. 1977: breeding stress of female eiders in maine. j. wildl. manage. 41, 360–373. lack, d. 1967: the signifi cance of clutch size in waterfowl. wildfowl 18, 125–128. laurila, t. & hario, m. 1988. environmental and genetic factors infl uencing clutch size, egg volume, date of laying and female weight in the common eider somateria mollissima. finn. game res. 45, 19–30. lewis, h. f. 1939: size of sets of eggs of the american eider. j. wildl. manage. 3, 70–73. lopoukhine, n., prout, n. a. & hirvonen, h. e. 1978: the ecological land classifi cation of labrador: a reconnaissance. environment canada, series 4. meades, s. j. 1990: natural regions of newfoundland and labrador. st. john’s, newfoundland: protected areas association of newfoundland and labrador. mendall, h. l. 1980: intergradation of eastern north american common eiders. can. field nat. 94, 286–292. merkel, f. r. 2004: evidence of population decline in common eiders breeding in western greenland. arctic 57, 27–36. milne, h. 1974: breeding numbers and reproductive rate of eiders at the sands of forvie national nature reserve, scotland. ibis 116, 135–154. mohr, c. o. 1947: table of equivalent populations of north american small mammals. am. midl. nat. 37, 223–249. nakashima, d. j. & murray, d. j. 1988: the common eider (somateria mollissima mollissima) of eastern hudson bay: a survey of nest colonies and inuit ecological knowledge. environ. stud. revolv. funds rep. 102. nettleship, d. n. 1980: census techniques for seabirds of arctic and eastern canada. canadian wildlife service occasional paper 25. ottawa. nettleship, d. n. & evans, p. g. h. 1985: distribution and status of atlantic alcidae. in d. n. nettleship & t. r. birkhead (eds.): the atlantic alcidae. pp. 53–154 london: academic press. robertson, g. j. 1995: annual variation in common eider egg size: effects of temperature, clutch size, laying date, and laying sequence. can. j. zool. 73, 1579–1587. robertson, g. j. & gilchrist, h. g. 1998: evidence of population declines among common eiders breeding in the belcher islands, northwest territories. arctic 51, 378–385. robertson, g. j. reed, a. & gilchrist, h. g. 2001: clutch, egg and body size variation among common eiders breeding in hudson bay, canada. polar res. 20, 85–94. 130 regional and annual variability in eider nesting ecology rohwer, f. c. 1992: the evolution of reproductive parameters in waterfowl. in b. d. batt et al. (eds.): ecology and management of breeding waterfowl. pp. 486–539. minneapolis: univ. minnesota press. ryder, j. p. 1970: a possible factor in the evolution of clutch size in ross’ goose. wilson bull. 82, 5–13. schmutz, j. k., robertson r. j. & cooke, f. 1983: colonial nesting of the hudson bay eider duck. can. j. zool. 61, 2424–2433. scott, j. m., heglund, p. j., morrison, m. l., haufl er, j. b., raphael, m. g., wall, w. a. & samson, f. b. (eds.). 2002: predicting species occurrences: issues of accuracy and scale. covelo, ca: island press. sokal, r. r. & rohlf, f. j. 1995: biometry: the principles and practice of statistics in biological research. third edition. san francisco: w.h. freeman and company. swennen, c. 1983: reproductive output of eiders (somateria mollissima mollissima) on the southern border of its breeding range. ardea 71, 245–254. swennen, c. & van der meer, j. 1992: variation in egg size of common eiders. ardea 80, 363–373. swennen, c. 2002: development and population dynamics of common eider somateria mollissima colonies in the netherlands. in h. noer & g. nehls (eds.): population processes in the common eider somateria mollissima. danish review of game biology 16. rønde, denmark. weller, m. w. 1956: a simple fi eld candler for waterfowl eggs. j. wildl. manage. 20, 111–113. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice research note establishment of a committee for norwegian stratigraphy at a meeting of the norwegian council of geology (norsk geologirad) on 5 may 1982, a resolution was passed for the establishment of a committee for norwegian stratigraphy norsk stratigrafisk komite (nsk) which will operate under the council’s auspices and ultimate control. at a statutory general meeting of the committee on 5 january 1983, anna siedlecka, geological survey of norway, was voted in as chair woman with tore torske (university of t r o m s ~ ) as vice chairman. status the committee for norwegian stratigraphy is a select com mittee under the control of the norwegian council of geology. in certain cases. decisions taken by the committee can be forwarded to the norwegian council of geology for their ruling. mandates the committee for norwegian stratigraphy has been author ized to carry out the following tasks: 1. to draw up and present a guide to stratigraphical procedure and nomenclature in norway. 2. to give approval to existing and new terminology in nor wegian stratigraphy. 3. to establish and maintain a computer-based archive of terms and names used, including those judged as invalid. this applies to stratigraphic units in use on the norwegian main land, in arctic and antarctic land areas under norwegian jurisdiction, and on the related continental shelves. 4. to produce and continually up-date a stratigraphic glossary for the areas mentioned under point 3. the glossary will contain an inventory of (a) all types of stratigraphic units (including those for biostratigraphy. chronostratigraphy, lith ostratigraphy, lithodemy, morphostratigraphy, and tecto nostratigraphy as well as major tectonic structures); (b) tables showing correlative stratigraphic units both within norway and in other, neighbouring countries. 5 . to maintain a continual control of, and provide advice on, the introduction of all new stratigraphical unit names and terms. composition and working routine the norwegian council of geology has appointed the members and deputy members for a four-year period, with the possibility of re-election for a further four-year period. the appointed members of the committee for norwegian stratigraphy were chosen such as to provide the most comprehensive coverage of all types and ages of stratigraphy (precambrian to recent) within the land and shelf areas mentioned under point 3. the committee will deliver an annual report to the nor wegian council of geology on its activities and future plans. in addition, at least once a year it will make known, possibly through publication, all the approved, new, stratigraphical unit names. the committee’s secretariat and computer archive are based at the geological survey of norway (ngu), trondheim. advice to authors authors intending to introduce new names and units or redefine pre-existing names and units in manuscripts prepared for pub lication arc encouraged to submit the proposed nomenclature to the committee for norwegian stratigraphy for its ruling. authors will be requested to provide details of each unit on forms specially devised for this purpose. these forms can be obtained from the committee’s secretariat: norsk stratigrafsk komitk, norges geologbke unders(kelse, p.o. box 3006, n-7001 trondheim, norway. invited keynote address the aim of the symposium gunter weller, university of alaska fairbanks chairman, scientific steering committee the polar regions play a crucial role in global climate change. they are sensitive indicators of change and their snow and ice features are good integrators of change. they store long-term climatic records in their ice sheets, such as the antarctic and greenland ice sheets. they also affect the global climate directly through interac tions between their atmospheres, ice cover, and oceans, and through feedback processes. practi cally all climate models predict an amplification of the global greenhouse effect at high latitudes, but models as well as observations have produced results that are not easily interpreted. there are large differences, for example, between the results of various gcm simulations, and uncertainties exist about the magnitude and timing of the expected changes. also, the observed high latitude climate trends over the last few decades are much more regional and patchy than predicted by the models. models are improving, however, with the introduction of sulphate aero sols and the elimination of flux adjustments and while considerable uncertainties remain in the long-term prediction of change there is some agreement between model results and observed trends by season on shorter time scales. the warming observed over the landmasses of the arctic and in the arctic ocean over the last few decades is matched by corresponding observed changes i n the cryosphere, including decreases in snow cover and glacier mass balances. thawing of permafrost, and by reductions in sea ice extent and thickness. in antarctica, warming in the antarctic peninsula and ross sea regions is associated with dramatic reductions in ice shelf areas and reduced ice thicknesses on the lakes in the mcmurdo dry valleys. a warmer climate in future will accelerate permafrost thawing on land and thus affect ecosystems and humans, it will change the productivity of marine ecosystems in the arctic and southern oceans, will have economic impacts on fisheries, petroleum production and other human activities, and will cause social conse quences on northern indigenous populations. while uncertainties exist about the future, climate change in the polar regions during the past few decades can be shown to have already had major impacts which will become much more pro nounced if present trends continue. the key questions that need to be answered to remove some of the uncertainties include the following: are we already seeing a climate change due to the greenhouse effect, as predicted by gcms, and if not when are we likely to see it, and where? are the changes in climate that we see $h the polar regions due to natural or man-’made causes, or both; and if both, what are their relative contributions to change? 0 what parameters, processes and interactions past, present and future do we need to understand better in order to predict future climate change? what are the likely impacts of global change on the polar environment and people and of polar processes and feedbacks on the global climate and society? the aim of this symposium is to begin to answer at least some of these questions. weller 1999: polar research 18(2), 115 115 recent status of bowhead whales, balaena mysticetus, in the wintering grounds off west greenland randall r. reeves and mads peter heide-jbrgensen reeves, r.r. & heide-jergensen, m.p. 1996: recent status of bowhead whales, balaena mysticetus, in the wintering grounds off west greenland. polar research 15 ( 2 ) , 115-125. bowhead whales, balaena mysticetus, belonging to the davis straitlsaffin bay stock, have historically wintered in baffin bay and davis strait, including waters along the west coast of greenland in and near the entrance of disko bay. aerial surveys of the disko bay region during late winter (1981, 1982, 1990, 1991, 1993 and 1994) showed that it was still visited regularly by a few tens of whales. commercial whaling on bowheads in baffin bay and davis strait ended in about 1915, but occasional killing continued until as recently as the 1970s. the low numbers of bowheads observed off west greenland in recent years are consistent with the results of surveys of the summering grounds in the eastern canadian arctic, indicating that any recovery has been exceedingly slow. the only conclusion supported by the data is that the current stock size is a small fraction of what it was prior to commercial whaling. randall r. reeves, okapi wildlife associates, 27 chandler lane, hudson, quebec jop lh0, canada; mads peter heide-j@rgensen, greenland institute of natural resources, c / o national environmental research institute, tagensvej 135, dk-2200 copenhagen n, denmark. introduction the stock of bowhead whales, balaena mystice ?us, centred in davis strait and baffin bay (the davis straitdaffin bay stock) consisted of at least 12,000 whales in 1820 (woodby & botkin 1993). since the whaling grounds off west greenland had already been depleted by then (ross 1993), the abundance prior to the start of commercial whaling in this region (early 1700s) must have been considerably greater than 12,000. the current stock size has been estimated at about 250 (finley 1990) or 350 whales (zeh et al. 1993). by far the largest concentrations of bowheads in the eastern north american arctic occur in isabella bay, northeastern baffin island, canada, the site of the only dedicated field study ever conducted on this stock (finley 1990). one individual photographed in isabella bay in late september 1986 was re-photographed in the pack ice near the entrance of disko bay in early april 1990 (heide-j~rgensen & finley 1991). eschricht & reinhardt (1866) summarised information on the bowhead's occurrence off west greenland, deriving data mainly from journals kept at whaling stations on shore. since then, little has been published about this species in greenland apart from reports of opportunistic observations. born & heide-j~rgensen (1983) summarised observations near qeqertarsuaq (godhavn; see fig. 1 for localities), and kapel (1985) reported the capture of a young bowhead in a net set for white whales, delphinapterus leucas, near upernavik. during a 29-day ice breaker cruise in davis strait and baffin bay, february-march 1976, turl (1987) saw one bowhead off the mouth of disko bay (ca. 68"n, systematic aerial surveys of marine mammals in west greenland waters have provided some quantitative data on bowheads. we have analysed these data and evaluated the current distribution and abundance of bowheads in this part of the davis straitdaffin bay stock's range. 54"w). material and methods systematic aerial surveys of west greenland waters were conducted during march 1981 and 1982 with the principal objective of documenting the distribution and abundance of marine mam mals along a proposed liquid natural gas tanker route (mclaren & davis 1981, 1983). another series of aerial surveys, stratified to provide intense coverage of the core winter distribution of the baffin bay stock of white whales, was conducted during march 1991,1993 and 1994 and april 1990 (heide-jmgensen et al. 1993; heide 116 r. r. reeves & m . p. heide-jqrgensen j~rgensen & reeves 1996). some of the effort in these latter surveys, especially to the north of the main white whale strata, was intended to cover the winter distribution of walruses, odobenus ros marus, off central west greenland (born et al. 1994). the present study uses sightings and effort data from all six sets of surveys to assess bowhead distribution and abundance. for the 1981 and 1982 surveys we extracted data from the figures presented by mclaren & davis (1981, 1983), whereas for the other four surveys we used the original field data. it was assumed that the criteria and methods for surveying white whales in the 1990s surveys, e.g. low wind speeds (sea states 5 3 on the beaufort scale), good visibility (> 1 km), slow flying speed (160-17okmbr) and a target survey altitude of 750 ft (228 m) above sea level, also ensured optimal conditions for detecting bowheads. the 1981-82 surveys were flown at a lower altitude (150 m) and higher speed (about 220 kmbr), probably rendering them less efficient for detecting animals in the surveyed strips. from the positions of 23 (92%) of the 25 bowheads sighted in the aggregate data set, a stratum for bowhead late-winter (march-april) distribution off west greenland was constructed (fig. 1). this stratum has an area of 21 260 km2. it is delimited to the west and north by heavy pack ice at 56"w and 69"10'n, respectively, to the south by large expanses of open water and to the fig. 1. baffin bay and davis strait regions showing places mentioned in text and the bowhead stratum used in this paper for abundance estimation off west greenland. dots are positions of bowhead kills, april-june, as recorded in whaling logbooks and journals from british and north american archives, 1829-1910 (ross & maciver 1982). the kill positions are illustrative only. additional kills were recorded outside the mapped area. recent status of bowhead whales in the wintering grounds off west greenland 117 east by land. the two sightings outside the bow head stratum were within about 75 and 25 km of its borders, respectively. the low number of sightings precluded any detailed statistical scrutiny of the abundance estimation technique. instead, simple strip-census estimates were calculated for each year. an effective strip width of 700 m on either side of the aircraft was assumed for all years. this strip width is reasonable for the distribution of sighting distances obtained in the 1990s surveys (fig. 2). mclaren & davis (1981, 1983) limited their search to an area within 800 m on either side of the flight path. two sightings (3 animals) in 1994 were at distances greater than 700 m and therefore were not used for calculating that year’s abun dance estimate. results the observed winter distribution of bowheads was fairly consistent off west greenland from year to year. sightings in march and early april tended to be clustered in an area off the mouth of disko bay south to kangaatsiaq (68’00”) (figs. 3-8). bowheads were sighted at least once in all of the surveys. point estimates of relative abundance ranged from as few as 6 in 1993 to 51 in 1991, but all of the estimates had low precision (table 1). the only conclusion supported by these data is that at least a few tens of bowheads were present in west greenland waters in the years with surveys. most of the bowhead sightings were of solitary individuals although groups of up to 3 or 4 closely associated animals have been reported occasion ally (born & heide-j~rgensen 1983). a group of 4 was seen in the 1982 survey, and a closely associated pair of large animals was seen in 1994. discussion distribution and seasonal movements historically, bowheads were found in winter as far south as labrador in eastern canada and about 64”n in west greenland (eschricht & reinhardt 1866; reeves et al. 1983). the area surrounding the mouth of disko bay, where the tongue of permanently open water along the east side of davis strait ends, was well known for its winter and spring concentration of bowheads (fig. 1). according to journals of the whaling station at sisimiut (holsteinsborg; 66’56”) from 1780 to 1839, bowheads usually arrived there in mid december and began migrating north by mid march (eschricht & reinhardt 1866). somewhat farther north at qeqertarsuaq (69’14”) the whales were usually present until mid june (eschricht & reinhardt 1866). assuming that the present-day migratory schedule is similar to the historical one, the timing of the 1990s surveys reported here, as well as those of mclaren & davis (1981, 1983) and born & heide-j~rgensen (1983), should have been about right for catching 1 1 0 400 800 1200 1600 perpendicular dirtance from trackline (metres) fig. 2. perpendicular distances to sightings of bowheads in 1990,1991,1993 and 1994. the two sightings more than 700 m from the trackline were not used for abundance estimation. note that the counts (y-axis) are sightings and not individuals; some of the sightings were of more than one individual. table 1. strip-census estimates of bowhead abundance in the bowhead stratum off west greenland. data from 1981-82 were extracted from mclaren & davis (1981, 1983). year 1981 1982 1990 1991 1993 1994 sum effort (w observations (individuals) n 1615 2121 993 2101 2271 2890 3 6 1 7 1 2* 20** density n h z 0.0013 0.0020 0.0007 0.0024 0.0003 0.0005 abundance (95% ci) 28 (10-79) 15 (2-90) 51 (21-119) 6 ( 1 4 4 ) 43 (5-333) 11 (3-37) * two sightings (3 individuals) in 1994 were outside the 700 m strip width. * * a total of 23 observations within the bowhead stratum, 3 of which were outside the strip; 2 additional sightings of single bowheads were made outside the s t r a t u m 4 n e in 1981 (fig. 3) and one in 1982 (fig. 4). 7 0" '; . . . . 66 "n .. . f ig . 3 . t ra ns ec ts fl ow n (s ol id li ne s) a nd b ow he ad s si gh te d in 1 98 1 (r ed ra w n fr om m cl ar en & d av is 1 98 1) . t he b ow he ad s tr at um i s bo un de d by b ro ke n lin es . f ig . 4 . t ra ns ec ts fl ow n (s ol id li ne s) a nd b ow he ad s si gh te d in 1 98 2 (r ed ra w n fr om m cl ar en & d av is 1 98 3) . t he b ow he ad s tr at um i s bo un de d by b ro ke n lin es . 914 a p ri l1 99 0 0 1 ln dw td ua l ! i i i i 1 i / i \ m \, '. '. \ \ m k m f ig . 5 . t ra ns ec ts fl ow n (s ol id l in es ) a nd b ow he ad s si gh te d in 1 99 0. t he b ow he ad st ra tu m is b ou nd ed b y br ok en l in es . 19 -2 4 m ar ch 1 99 1 0 1 in di vi du al 1 i \ 6 ( m k m f ig . 6 . t ra ns ec ts fl ow n (s ol id li ne s) a nd b ow he ad s si gh te d in 19 91 . t he b ow he ad st ra tu m is b ou nd ed b y br ok en l in es . n ot e th at t he t w o a ni m al s on l at itu de 6 7% " w er e se en to ge th er a t 54 "1 7' w. i 124 m ar ch i 99 4 1 0 1 in di vi du al i i i i '+ i i i m \ \ . \ \ > , \ \ ' \ m \ \ \ \ > , \ \ ' fi g. 7 . t ra ns ec ts f lo w n (s ol id li ne s) a nd b ow he ad s si gh te d in 1 99 3. i rr eg ul ar ity o f th e lin es i s du e to t he f ac t th at t he y sh ow a ct ua l ro ut es f lo w n. t he b ow he ad s tr at um i s bo un de d by b ro ke n lin es . fi g. 8 . t ra ns ec ts f lo w n (s ol id l in es ) an d bo w he ad s si gh te d in 1 99 4. ir re gu la ri ty o f th e lin es i s du e to t he f ac t th at t he y sh ow a ct ua l ro ut es f lo w n. t he b ow he ad s tr at um i s bo un de d by b ro ke n lin es . n ot e th at t w o of t he a ni m al s on l at itu de 6 7" 55 'n w er e se en to ge th er a t 54 "2 7' w . c l h ) 0 3 3 recent status of bowhead whales in the wintering grounds off west greenland 121 the peak residency of bowheads in at least the northern portion of our bowhead stratum. it is not surprising that the bulk of recent sightings in march and april have been in or just outside the mouth of disko bay (born & heide-j~rgensen 1983; figs. 3-8). bowheads can still be seen in this general area until well into mid may. for example, heide-j~rgensen (unpubl. data) sighted one at 68"50.40'n, 53"24.70'w on 7 may 1992 during a cruise to the north and at 68"54.40'n, 53"42.67'w on 15 may 1992 during his return passage south. d. boertmann and a. mosbech of the national environmental research institute in copenhagen (pers. comm.) observed bowheads in this same area during low-altitude aerial surveys of seabirds between 29 a p r i l 4 may 1996 (4 sightings, 5 animals). bowheads in the west greenland wintering area at any one time represent only a part of the davis straitbaffin bay stock. according to present understanding, this stock includes all of the whales that summer in the eastern canadian high arctic or northwest greenland and migrate southwards in autumn along either the east coast of baffin island or west greenland. finley & renaud (1980) found no bowheads in the baffin bay "north water", a flaw lead system (or polynya) in northern baffin bay, during aerial surveys in march-april 1978 and march 1979, but two sightings were made during a similar survey in march 1993 one animal at the mouth of jones sound and another northwest of coburg island (p.r. richard, canadian department of fisheries & oceans, winnipeg, pers. comm.). two bowheads engaged in courtship behaviour were seen along the ice edge in smith sound at 77"n, 72"w on 10 may 1996 (a. mosbech, pers. comm.). bowheads have also been seen during february and march in heavy ice well away from the greenland coast to as far north as 6t30' 69"oo'n (e.g. duncan 1827; m'clintock 1860). the stock affinities of bowheads that winter off southeastern baffin island and in the labrador sea are uncertain, as some or all of them may be migrants from the summering areas in northern hudson bay and foxe basin (cf. reeves and mitchell 1990). kapel (1985) interpreted the capture in autumn at upernavik (mentioned above) as demonstrating the continued use of a traditional southward migration route along the west coast of greenland. while some whales may use this route, the paucity of bowhead observations by greenlandic hunters, who are regularly at sea hunting white whales, narwhals, monodon monoceros, and seals during the autumn (cf. heide-jgrgensen 1994), is in striking contrast to the situation off north eastern baffin island, where a nearshore autumn migration is well documented from scientific investigations (davis & koski 1980; finley 1990) and observations by local hunters (anon ymous 1995). numbers and trends it is important to bear in mind that bowheads can dive for periods of at least 40 min and that they may spend 80% or more of their time below the surface and thus be unavailable for sighting (dorsey et al. 1989; wiirsig & clark 1993; finley & goodyear 1993). the availability bias in survey results presented here is not measurable, as the percentage of time at the surface depends on activity state (e.g. feeding, socialising, travelling, resting) and other confounding variables (ri chardson et al. 1995). the settlement kitsissuarsuit (hunde ejland) is situated in the southern part of the mouth of disko bay. the inuit there derive a large part of their annual sustenance and income from hunting narwhals. during february-april they keep daily look-outs for whales, but bowheads have been observed only occasionally (e.g. one to the west of the island on 27 march 1990; heide-jsrgensen, unpubl. data; also see born & heide-j~rgensen 1983). the hunters have not noted any increase in sightings despite the fact that more dinghies are being used each winter to search a larger and larger area for whales. the fishing banks off west greenland are visited by shrimp trawlers and other types of vessels, e.g. cutters and dinghies, at all seasons, including periods in late winter and spring when the pack ice is navigable. in addition, the land-fast ice along the mouth of disko bay is used for hunting trips by dog sledge. the combined effort of all these types of traffic has increased enormously during the post-war period, especially during the past 30 or 40 years with the advent and proliferation of mechanical transportation (mattox 1973; horsted 1978; rask 1993), in combination with rapid human population growth (lyck & taagholt 1987). in qeqertarsuaq municipality alone, the vessel fleet in 1989 consisted of four large multi-purpose trawlers and 19 smaller fishing cutters, as well as several hundred 122 r. r. reeves & m . p. heide-jgrgensen dinghies (= skiffs) with 40+-horsepower outboard motors (caulfield 1993). yet in spite of the regular and widespread human presence at sea, few reports of bowheads have been received from this or any other area of west greenland. some bowheads presumably follow the shore lead (the commercial whalers called it the “land water”) along the coast of west greenland during their northward spring migration, much as the 19th century british whalers did (cf. scoresby 1820; barron 1970). the shore lead along the west coast of disko island during march and april is extremely narrow (usually < 2 km wide), bordered by land or land-fast ice to the east and by the dense pack ice of baffin bay to the west. to a certain extent, the shore lead can be perceived as a bottleneck for whales travelling north from the relatively extended wintering grounds in davis strait and the labrador sea. the same lead west of disko island is also used by hunters as they pursue white whales, narwhals, walruses and seals during the late winter and early spring. although these hunters do observe bowheads, the numbers are few ( < l o sightings per year; e.g. born & heide-j~rgensen 1983). if a major increase in local bowhead abundance had occurred over the last few decades, it definitely would have been noticed by the greenlanders. it is important to recognise, however, that ice cover does not restrict bowhead movements to nearly the same degree as it does vessel passage, so it should not be assumed that all, or even most, of the whales migrate northwards through the shore lead off disko. group size, group composition and behaviour it is unlikely that the small mean group size from the aerial survey data (1.6 f sd 1.2) is an artifact of survey procedures because the routine practice (at least during the four sets of surveys in the 1990s) was to interrupt level flight and circle above bowhead sightings for photography. in these circumstances, additional animals in the vicinity should have been detected. bowheads in other stock areas are known to migrate in waves or pulses, with young (weaned but immature) animals often travelling separately from adults (braham et al. 1984; moore & reeves 1993). similar segregation has been reported on the summering grounds in the beaufort sea (cubbage & calambokidis 1987). finley (1990) found that the late-summer “resident” whales in isabella bay consist mainly of large adults, with few calves and small subadults present. whaling manuscripts from the late 19th and early 20th centuries, along with recent observations of large adults accompanied by small calves off northern baffin island, reinforce the idea that the davis strait stock is segregated to some degree during the summer and autumn (finley 1990; finley & darling 1990; reeves & mitchell 1991). rela tively few observations of bowheads have been made on any of the wintering grounds (reeves et al. 1983; moore & reeves 1993). the observa tions reported here include animals subjectively classified as small subadults (< 10 m) as well as sexually mature adults (> 13 m; see koski et al. (1993) and schell & saupe (1993) for discussions of size at age in bowheads). no calves were seen during the aerial surveys, but several sightings of calves have been reported by local hunters in west greenland (anonymous 1981; born & heide-j~rgensen 1983). although sexual activity in bowheads can be observed at various times of the year, most conceptions are believed to occur in the late winter or spring (koski et al. 1993). eschricht & reinhardt (1866) reported that boisterous sexual activity was typical of bowheads near sisimiut during january and february. two large animals that we observed off kangaatsiaq on 14 march 1994 were interacting vigorously at the surface, rubbing bodies and rolling in apparent courtship. exploitation, protection and prospects for recovery in a reconstruction of the davis strait stock’s catch history, mitchell & reeves (1982) con cluded that no bowheads had been killed by greenlanders after 1956. however a published summary of greenland hunting statistics (anonymous 1977), supplemented by unpublished correspondence (letters between l. vesterbirk, ministry for greenland, copenhagen, and e. vangstein, international whaling statistics, san defjord, norway, 1973-74), indicates that one bowhead was taken at qeqertarsuaq in april 1973. thus, although commercial whaling for bowheads had ended in both canada and greenland by about 1915, some killing continued in both countries into the 1970s (mitchell & reeves 1982). documented post-1915 kills in greenland include one at qeqertarsuaq in april 1928 (rosendahl 1957) and one in the atammik-napasoq area recent status of bowhead whales in the wintering grounds off west greenland 123 (approx. 64”30’45”00’n) in march 1956 (freuchen & salomonsen 1958) in addition to the one at qeqertarsuaq in 1973. bowheads have been legally protected by international agreements for more than 50 years, although the international whaling commission (iwc) sanctions continued hunting by alaskan eskimos for subsistence (gambell 1993). the greenlanders’ hunting of minke whales, balaen optera acutorostrata, and fin whales, balaenop tera physalus, is managed by a quota system under the iwc’s aboriginal subsistence whaling scheme (gambell 1993; caulfield 1993). the bowhead is fully protected in greenland waters. canada withdrew from the iwc in 1982, and bowhead whaling was initiated on a small scale in the western canadian arctic (bering-beaufort chukchi seas stock) in 1991 (freeman et al. 1992). a similar initiative in the eastern canadian arctic began prematurely in 1994 when a small bowhead was taken illegally in northern foxe basin (anonymous 1994; george 1995). the establishment of a “total allowable harvest” of at least one bowhead in the eastern canadian arctic was mandated under the recent nunavut land claim agreement (indian & northern affairs canada 1993). initiation of whaling was to be preceded by the commencement of “an inuit knowledge study to record sightings, location and concentrations of bowhead whales in the nunavut settlement area” (indian & northern affairs canada 1993, p. 38). early results from the study reflect the firm belief by inuit that bowhead numbers have increased substantially since the end of commercial whaling (anonymous 1995). aerial surveys in northern foxe basin and north western hudson bay in 1994 and 1995 have been interpreted as suggesting that at least 200-300 bowheads summer there (anonymous 1996). a large bowhead was taken in a legal hunt at repulse bay, northwestern hudson bay, on 15 august 1996 (rassel 1996). intensive scientific monitoring of some other severely depleted stocks of baleen whales has demonstrated that they are recovering under protection or conservative hunt management (best 1993). the data presently available from surveys are clearly inadequate for demonstrating recent or current trends in the davis straitbaffin bay stock of bowheads. they do indicate, however, that the total population size remains a small fraction of what it was prior to commercial whaling. sub stantial recovery seems not to have occurred in the greenland portion of this stock’s range. hunters and fishermen in west greenland have reported few encounters with bowheads and have not suggested that the stock is increasing. the paucity of sightings cannot be explained by too little time spent at sea in late winter and early spring. in fact, much boating and shipping activity takes place in the open water and loose pack ice along the west coast of greenland, where bowheads were once seasonally plentiful. the rarity of sightings during aerial surveys is consistent with the shortage of reports by local people. if the davis straitdaffin bay bowhead stock were increasing, it would appear to be doing so mainly in the western part of its range. our data from west greenland corroborate the conclusions of davis & koski (1980), finley (1990) and zeh et al. (1993) that the stock is at a small fraction of its pre-whaling level of abundance and that any recovery since the early 1900s has been very slow. initiation of whaling on bowheads in the eastern north american arctic must be consid ered in an international context. some whales move back and forth between canada and greenland, possibly on an annual basis. others may occur during the winter in the labrador sea outside any coastal state’s exclusive economic zone. if an objective of management is to allow for substantial population recovery, and we believe that it should be, then complete or nearly complete protection from hunting will be neces sary for decades into the future. also, we believe that canada has an obligation to seek international cooperation on bowhead conservation and to subject its programmes of bowhead population assessment and hunt management to independent scrutiny. acknowledgements. w e are grateful to the fisheries directorate of the greenland home rule government for sponsoring the white whale and walrus surveys during 1990 94. our fellow whale spotters, j. teilmann, j. jensen and l. petersen (who also piloted the aircraft), deserve special thanks. the surveys in 1981 and 1982 were conducted by lgl ltd. and funded by the arctic pilot project. j. jensen kindly compiled the information on post-1915 bowhead hunting in greenland. d. boertmann and a. mosbech of the danish national environmental research institute, department of arctic environment, copenhagen, very generously allowed us to cite their unpublished bowhead observations. p. barry helped prepare the map figures. data analysis and manuscript preparation were made possible by the support of the greenland institute of natural resources, nuuk, and by a grant from the whale & dolphin conservation society, bath, avon, u.k. 124 r. r. reeves & m . p. heide-j@rgensen references anonymous 1977: hunting statistics based on the green landers’ list of game caught in greenland in the period 1/1 31/12 1973 purchase of products by the royal greenland trade department in 1973. ministry for greenland, copen hagen. anonymous 1981: denmark (greenland) progress report on cetacean research 1978-79. rep. int. whal. comm. 31, 185 186. anonymous 1994: elder’s wish outweighs law, hunters say. toronto globe and mail, 26 september, p. a7. anonymous 1995: nunavut bowhead traditional knowledge study. preliminary report based on interviews conducted during 1995. report presented at the meeting of the nunavut wildlife management board, rankin inlet, northwest territories, 1&16 nov. 1995. 24 pp. + appendices. anonymous 1996: report of the national marine mammal peer review committee, winnipeg, manitoba, 7-8 march 1996. government of canada, department of fisheries and oceans. barron, w. 1970: old whaling days. conway maritime press, greenwich. 211 pp. (first publ. in hull, by w. andrews & co., 1895). best, p. b. 1993: increase rates in severely depleted stocks of baleen whales. ices j. mar. sci. 50, 169-186. born, e. w. & heide-j~rgensen, m.-p. 1983: observations of the bowhead whale (balaena mysricetus) in central west greenland in march-may 1982. rep. int. whal. comm. 33, 545-547. born, e. w., heide-jorgensen, m. p. & davis, r. a. 1994: the atlantic walrus (odobenus rosmarw rosmarus) in west greenland. medd. grenl. biosci. 40, 1-33. braham, h. w., krogman, b. d. & carroll, g. m. 1984: bowhead and white whale migration, distribution, and abundance in the bering, chukchi, and beaufort seas, 1975-78. noaa tech. rep. nmfs ssrf-778, 1-39. caulfield, r. a. 1993: aboriginal subsistence whaling in greenland: the case of qeqertarsuaq municipality in west greenland. arctic 46, 144-155. cubbage, j. c. & calambokidis, i. 1987: size-class segregation of bowhead whales discerned through aerial stereophoto grammetry. mar. mamm. sci. 3, 179-185. davis, r. a. & koski, w. r. 1980: recent observations of the bowhead whale in the eastern canadian high arctic. rep. int. whal. comm. 30, 439-444. dorsey, e. m., richardson, w. j. & wdrsig, b. 1989: factors affecting surfacing, respiration, and dive behaviour of bowhead whales, balaena mysticetus, summering in the beaufort sea. can. j. zool. 67, 1801-1815. duncan, d. 1827: arctic regions, voyage to davis’ strait, by david duncan, master of the ship dundee. london: privately published. 126 pp. eschricht, d. f. & reinhardt, j. 1866: on the greenland right whale (balaena mysricerus, linn.). pp. 1-150 i n flower, w.h. (ed.): recent memoirs on the cetacea by professors eschricht, reinhardt and lilljeborg. published for the ray society by robert hardwicke, london. finley, k. j. 1990 isabella bay, baffin island: an important historical and present-day concentration area for the endangered bowhead whale (balaena mysticetus) of the eastern canadian arctic. arctic 43, 137-152. finley, k. j. & darling, l. m. 1990: historical data sources on the morphometry and oil yield of the bowhead whale. arctic 43, 153-156. finley, k. j. & goodyear, j. d. 1993: dive patterns and feeding habitat of the bowhead whale in baffin bay. 10th biennial conference on the biology of marine mammals, galveston, texas, u.s.a., 11-15 november. abstracts, p. 48. finley, k. j. & renaud, w. e. 1980 marine mammals inhabiting the baffin bay north water in winter. arctic 22, 724-738. freeman, m. m. r., wein, e. w. & keith, d. f. 1992: recovering rights. bowhead whales and inuvialuit subsis tence in the western canadian arctic. canadian circumpolar institute and fisheries joint management committee (studies on whaling 2), edmonton, alberta. 155 pp. freuchen, p. & salomonsen, f. 0. 1958: the arctic year. g. p. putnam’s sons, new york. gambell, r. 1993: international management of whales and whaling: an historical review of the regulation of commercial and aboriginal subsistence whaling. arctic 46, 97-107. george, l. 1995: leaders rally in support of igloolik hunters. nunatsiaq news (iqaluit, nwt, canada), 3 february, pp. 1 2. heide-jorgensen, m. p. 1994: distribution, exploitation and population status of white whales (delphinapterus leucas) and narwhals (monodon monoceros) in west greenland. medd. grenl. biosci. 39, 135-149. heide-jorgensen, m. p. & finley, k. j. 1991: photographic reidentification of a bowhead whale in davis strait. arctic 44, 254-256. heide-jorgensen, m. p., lassen, h., teilmann, j. & davis, r. a. 1993: an index of the relative abundance of wintering belugas, delphinapterus leucas, and narwhals, monodon monoceros, off west greenland. can. j. fish. aquat. sci. 50, heide-jorgensen, m. p. & reeves, r. r. 1996: evidence of a decline in beluga, delphinapterw leucas, abundance off west greenland. ices j. mar. sci. 53, 61-73. hors+ed, sv. aa. 1978: rejerne ved gronland. fisk & hav 78. danmarks fiskeriunders~gelser 1978. 71 pp. indian & northern affairs canada 1993: agreement between the inuit of the nunavut settlement area and her majesty the queen in right of canada. tungavik federation of nunavut & minister of indian affairs & northern develop ment, ottawa. kapel, f. 0. 1985: a note on the net-entanglement of a bowhead whale (balaena mystrcehts) in northwest green land, november 1980. rep. int. whal. comm. 35,377-378. koski, w. r., davis, r. a,, miller, g. w. & withrow, d. e. 1993: reproduction. pp. 239-274 in burns, j. j., montague, j. j. & cowles, c. j. (eds.): the bowhead whale. society for marine mammalogy, lawrence, kansas, usa (spec. pub. 2323-2335. lyck, l. & taagholt, j. 1987: greenland-its economy and resources. arctic 40, 5c.59. mattox, w. 1973. fishing in west greenland 1910-1966. the development of a new native industry. medd. gronl. 197(1), 1-344 + appendix. mclaren, p. l. & davis, r. a. 1981: distribution of wintering marine mammals in southern baffin bay and northern davis strait, march 1981. report to arctic pilot project, calgary, alberta. recent status of bowhead whales in the wintering grounds off west greenland 125 mclaren, p. l. & davis, r. a. 1983: distribution of wintering marine mammals off west greenland and in southern baffin bay and northern davis strait, march 1982. report to arctic pilot project, calgary, alberta. m’clintock, f. l. 1860 the voyage of the ‘fox’ in the arctic seas, a narrative of the discovery of the fate of sir john franklin and his companions. boston: ticknor & fields. 375 pp. mitchell, e. & reeves, r. r. 1982: factors affecting abundance of bowhead whales ealaena mysricerm in the eastem arctic of north america, 1915-1980. biol. conserv. 22, 59-78. moore, s. e. & reeves, r. r. 1993: distribution and movement. pp. 313-386 in bums, j. j., montague, j. j. & cowles, c. j. (eds.): the bowhead whale. society for marine mammalogy, lawrence, kansas, usa (spec. pub. 2). rask, s. 1993: de f ~ r s t e erhvervsmotorbdde. om fangstens betydning for udviklingen i industrifiskeriet. tidsskr. grgnl. 1993(3), 1ocl118. rassel, j. van 1996: nunavut celebrates bowhead kill. nunatsiaq news (iqaluit, nwt, canada), 23 august. reeves, r. r. & mitchell, e. 1990 bowhead whales in hudson bay, hudson strait, and foxe basin: a review. naturaliste can. (r&. ficol. syst.) 117, 25-43. reeves, r. r. & mitchell, e. 1991: sc/43ips28. summer segregation in the davis strait bowhead whale stock. rep. int. whal. comm. 41, 762 (abstract only). reeves, r., mitchell, e., mansfield, a. & mclaughlin, m. 1983: distribution and migration of the bowhead whale, ealaena mysricerus, in the eastern north american arctic. arctic 36, 5-64. richardson, w. j., finley, k. j., miller, g. w., davis, r. a. & koski, w. r. 1995: feeding, social and migration behavior of bowhead whales, bnlaena mysticehcs, in baffin bay vs. the beaufort sea-regions with different amounts of human activity. mar. mamm. sci. 11, 1-45, rosendahl, ph. 1957: jakob danielsen. en grenlandsk maler. tegninger og akvareller. det grenlandske forlag, godthdb. ross, w. g. 1993: commercial whaling in the north atlantic sector. pp. 511-561 in burns, i. j., montague, i. j. & cowles, c. j. (eds.): the bowhead whale. society for marine mammalogy, lawrence, kansas, usa (spec. pub. 2). ross, w. g & maciver, a. 1982: distribution of the kills of bowhead whales and other sea mammals by davis strait whalers 1829-1910. report for arctic pilot project. calgary, alberta. schell, d. m. & saupe, s. m. 1993: feeding and growth as indicated by stable isotopes. pp. 491-509 in bums, j. j., montague, j. j. & cowles, c. j. (eds.): the bowhead whale. society for marine mammalogy, lawrence, kansas, usa (spec. pub. 2). scoresby, w., jr. 1820: an account of the arctic regions, with a history and description of the northern whale-fishery. archibald constable, edinburgh. 2 vols., 522 and 574 pp. turl, c. w. 1987: winter sightings of marine mammals in arctic pack ice. arctic 40, 219-220. woodby, d. a. & botkin, d. b. 1993: stock sizes prior to commercial whaling. pp. 387407 in bums, j. j., montague, j. j. & cowles, c. j. (eds.): the bowhead whale. society for marine mammalogy, lawrence, kansas, usa (spec. pub. wiirsig, b. & clark, c. 1993: behavior. pp. 157-199 in bums, j. j., montague, j . j. & cowles, c. j. (eds.): the bowhead whale. society for marine mammalogy, lawrence, kansas, usa (spec. pub. 2). zeh, j. e., clark, c. w., george, j. c., withrow, d., carroll, g. m. & koski, w. r. 1993: current population size and dynamics. pp. 409489 in bums, j. j., montague, j. j. & cowles, c. j. (eds.): the bowhead whale. society for marine mammalogy, lawrence, kansas, usa (spec. pub. 2). 2). killingtveit.indd 161killingtveit et al. 2003: polar research 22(2), 161–174 hydrological data from arctic regions are sparse, and svalbard is no exception. there were, for example, no regular monitoring stations for river runoff before 1990 and even today there are fewer than fi ve stations with continuous recording. water resources can easily become a limiting factor for development of industry and tourism, and knowledge about hydrological processes constitute an important link between global change scenarios and consequences for the arctic ecosystems. both for scientifi c studies and water management, it is important to know the amount of water in storage in the catchments (as glaciers, snow, groundwater and lakes) and the fl ux of water into or out of the catchments as precipitation, evaporation and runoff. water balance or water budget calculations is a method used by hydrologists to assess the water resources within an area, and to verify that the different measurements of hydrological terms are consistent and gives results that are correct. the water balance concept is based on the fact that during some time (a day, a month, a year, etc.) the total input of water to an area, for example water balance investigations in svalbard ånund killingtveit, lars-evan pettersson & knut sand this paper reviews and summarizes all known previous water balance studies in svalbard. an updated water balance computation was then done for the three water catchments with the best data: bayelva, de geerdalen and isdammen/endalen for 10 hydrological years 1990–2001. the computations were based on the best available data and correction methods. special emphasis was put on correction of precipitation data, both for catch errors and gradients in precipitation. areal precipitation in the three catchments is more than two times the measured precipitation at the closest meteorological station: 548 mm/year in de geerdalen, 486 mm/year in endalen/isdammen and 890 mm/year in bayelva. compared to this, average measured precipitation is only 199 mm/year at svalbard airport, close to endalen/isdammen and de geerdalen, and 426 mm/year in ny-ålesund, close to bayelva. evaporation is not well understood in svalbard; the best estimates indicate an average annual evaporation of ca. 80 mm/year from glacier-free areas, and no net evaporation from glaciers. glacial mass balance has in general been negative in svalbard during the last 40 years, leading to a signifi cant contribution to the water balance, on the order of 450 mm/year on average. annual runoff ranges from 545 mm in endalen/isdammen, 539 mm/year in de geerdalen up to 1050 mm/year in bayelva. runoff computed from water balance compares well with observed runoff, and average error in water balance is less than ± 30 mm/year in all three catchments. å. killingtveit, dept. of hydraulic and environmental engineering, norwegian university of science and technology, no-7491 trondheim, norway, aanund.killingtveit@bygg.ntnu.no; l.-e. pettersson, norwegian water resources and energy directorate, box 5091 majorstua, no-0301 oslo, norway; k. sand, statkraft grøner as, box 331, no-7403 trondheim, norway. 162 water balance investigations in svalbard a river catchment, will be balanced by the total amount of water leaving the area and changes in storage within the area. no water can disappear since it has to be accounted for in the budget. the water balance can, in principle, be calculated for any area, large or small, but in practice the water balance is usually calculated for a river drainage basin, also called a catchment. the usual formulation of the water balance equation for a river catchment is: pa – qs – qg – ea ± ∆m = ε , (1) where pa is precipitation input (mm), qs is surface (river) runoff from the catchment (mm), qg is groundwater runoff from the catchment (mm), ea is evaporation from the catchment (mm), ∆m is changes in water storage within the catchment (mm) and ε is an error term (mm). the error term ε should approach 0 if all the fi ve terms on the left side of the equation have been determined correctly. the magnitude of the error term indicates the accuracy of the different terms of the water balance. the type of errors and their magnitude will be different in different hydrological regimes, depending on climatic, geological and topographical conditions, and the quality of measurements. in arctic catchments many specifi c problems are encountered in the measurements. methodology—special problems in arctic catchments the problem of water balance computations in arctic catchments is illustrated in fig. 1. here, the measured runoff in bayelva (converted to mm) is compared to the measured precipitation at the nearest precipitation station at ny-ålesund (see fig. 2). the comparison is done for 12 hydrological years (a hydrological year is from 1 october to 30 september) with simultaneous observations of runoff and precipitation. this is a striking example of what is sometimes called the “hydrological paradox”. the paradox is that runoff seems to be much larger than precipitation. in reality, it should, of course, be the other way around, since all river runoff is ultimately generated from precipitation, and there will also be evaporation and possibly groundwater runoff removing some of the precipitation from the catchment. the paradox can be attributed to a combination of measurement errors, non-representative location of precipitation stations and net glacial melt during the period of study. by identifying and correcting these problems it is possible to establish the true value of each component in the water balance, and fi nally check the water balance in order to verify the computations. the computation of each individual term in the water balance, and some particular problems specifi c for arctic climate are described below. precipitation the term pa in the water balance is the average or areal precipitation in the catchment. this term is based on observed (measured) precipitation, but it will usually be higher than measured precipitation since precipitation measurements are affected by a number of error sources. in addition, precipitation gauges may not be placed in representative locations in the catchment, compared fig. 1. observed precipitation and runoff in bayelva. 163killingtveit et al. 2003: polar research 22(2), 161–174 to the areal precipitation variation. one particular problem of great importance is that precipitation usually increases with elevation, while most precipitation gauges are located in the lowlands. this is a highly signifi cant problem in svalbard where all precipitation stations are located close to sea level, while catchments may reach up to more than 1000 m a.s.l. the computation of areal precipitation in general is based on measurements in one or preferably several gauges located within or near the catchment. the computation usually consists of the following two steps. (1) the observed precipitation (po1, po2, … pon) is corrected for gauge catch errors to obtain true point precipitation values at the site of the precipitation gauges (pt1, pt2, … ptn). (2) areal precipitation (pa) can then be computed as an areal average for the catchment. this is based on the corrected point precipitation data: pa = f (pt1, pt2, … ptn). the method fig. 2. location of the three selected catchments in spitsbergen, svalbard: bayelva, endalen/isdammen and de geerdalen. 164 water balance investigations in svalbard for areal averaging must consider both regional and elevation gradients in precipitation distribution within the catchment. it is well known that precipitation measurements—in particular the measurement of snow precipitation—are subject to large errors (see, e.g. strutzer 1965, bogdanova 1968, larsson & peck 1974 and sevruk 1982). the measurement error nearly always leads to an observed precipitation that is less than the true point precipitation. correction methods for gauges in the nordic countries have recently been developed and reported by førland et al. (1996). error sources and correction methods were studied in the climate studies in the arctic project, where one of the sub-projects was to investigate the difference between measured and true precipitation at svalbard. results from this study and other relevant studies are reported by hanssenbauer et al. (1996). they conclude that “the seasonal ratio between true and measured precipitation varies between 1.26 for the summer and 1.70 for the winter. if it is supposed that the seasonal ratios which were found are typical for a normal year in ny-ålesund, the true normal (1961–1990) would be 550 mm, i.e. 50 % higher than the offi cial uncorrected value” (p. 37). water balance calculations by sand & bruland (1999) used the correction factors found by hanssen-bauer et al. (1996): 1.26 in june–august, 1.45 in september–november, 1.70 in december–february, and 1.57 in march–may. these correction factors were applied for the precipitation gauges both in ny-ålesund and at svalbard airport. elevation gradients in precipitation in mountainous catchments one usually fi nds that precipitation increases with increasing elevation, at least up to some elevation levels. in the nordic countries it is quite common to observe precipitation gradients of 5 10 % increase per 100 m increase in elevation. in svalbard all precipitation stations are located near sea level, and therefore the measured precipitation here can be much lower than the average (areal) precipitation in the catchments which may extend up to elevations of 500 1000 m a.s.l. or more (fig. 3). this problem was recognized when the fi rst attempts on water balance calculations were planned from 1990 onwards. the fi rst observational network for the study of precipitation gradients was set up in de geerdalen and close to longyearbyen. the average gradients found for precipitation during summer were 5 10 %/100 m. the true gradient may have been higher though, since the gauges located at higher elevations were more exposed to wind than those in lower and more sheltered areas (killingtveit et al. 1994). at ny-ålesund the orographic precipitation distribution was studied during the 1994 and 1995 summer seasons (førland et al. 1997a). a gradient of 20 %/100 m was found for summer precipitation, at least for elevations up to 300 m. this led to the conclusion that “the orographic precipitation enhancement, and catch defi ciency of conventional precipitation gauges may fully explain the apparent discrepancy between precipitation measured at ny-ålesund and runoff/ mass balance estimates for the bayelva catchment”. this result corresponds well with repp (1979), who found a gradient of 95 mm/100 m (ca. 20 %) and hagen & lefauconnier (1993, 1996) who used 25 %/100 m but who also pointed out that a linear gradient of 25 %/100 m might give too high values in the uppermost areas. mercier (2001) reported average gradients of 100 mm/ 100 m in a small catchment near zeppelinfjellet, which translates to ca. 12 %/100 m. sand & bruland (1999) used a gradient of 25 %/ 100 m in the bayelva catchment, with reference to hagen & lefauconnier (1993). in the lon don elva catchment they used a gradient of 31 %/100 m, a value found from analyses of snow survey data from the years 1996–98 in the same catchment. fig. 3. hypsographic curve for the three selected catchments. 165killingtveit et al. 2003: polar research 22(2), 161–174 finally, they used a gradient of 14 %/100 m in the de geerdalen catchment with reference to killingtveit et al. (1994). precipitation gradients during winter cannot easily be studied by direct precipitation measurements due to the large problems of measuring snow precipitation in higher and more wind-exposed locations. since snow in svalbard usually accumulates without any signifi cant melt events during the winter, it is possible to use snow on the ground as a measure for winter precipitation. this requires a careful selection of measurement sites to avoid problems due to wind redistribution of snow on the ground. tveit & killingtveit (1994) reported gradients of 85, 57, 20 and 85 mm /100 m for the four years 1991–94, based on analysis of snow surveys. this translates into relative gradients from 4 to 28 %/100 m, with an average around 14 %/100 m. winther et al. (1998) studied regional distribution of snow in svalbard as well as the elevation gradients. their study was supplemented by sand et al. (2003), who updated the results based on three years of snow surveys. the average gradient was 97 mm/100 m for the elevation range 100 1000 m a.s.l., which translates to 16 %/100 m. runoff runoff is usually the most reliably measured term in the water balance. since runoff is an integrated response from the whole catchment, the problem of representativity of stations does not exist for this term. still, there are other important problems and error sources, in particular in an arctic catchment. practically all continuous runoff measurements are done by calibrating a rating curve which shows the river fl ow (runoff) as a function of river water level (stage). the stage can fairly easily be recorded and the runoff computed as long as the rating curve is valid. most errors in runoff records are related to problems in establishing calibration and the stability of the rating curve, while the stage measurements in itself is relatively simple to perform. two of the most important problems sources in arctic rivers are unstable bed profi les at gauging stations and ice and snow blocking the river profi le. in svalbard, river runoff mostly occurs during a few months from june up to september. in the autumn all rivers freeze up completely, except short reaches of rivers fed by springs or in the front of some glaciers (petterson 1994). during the freeze-up process, large amounts of bottom ice may be formed, blocking the river profi le. later, during the winter, snow is swept down into the river channel and thick snow drifts may form, especially in deep gorges and ravines. when the snowmelt starts in the spring or early summer, the runoff often increases quite rapidly, fl owing into a river channel which is still blocked by ice and snow. in perennial rivers similar problems may occur when surface ice breaks up and creates iceruns and ice-jams in the river. in all these cases, the water level in the river, which is the property measured at gauging stations, may increase much more than the fl ow. the problem will gradually disappear as snow and ice is eroded and melted, but its magnitude and duration may be very diffi cult to determine, especially at remote stations with automatic measurements. evaporation evaporation from a catchment occurs from water surfaces, soil surface and vegetation. the total evaporation from the catchment is called areal or actual evaporation. areal evaporation is determined partly by the climate (potential evaporation) and partly by the wetness conditions in the catchment. in a dry desert, the potential evaporation may be very high, but the actual evaporation will be zero if there is no water. in arctic catchments the potential evaporation during the summer may be very signifi cant, due to high net radiation during days with 24 hours of sunshine. the amount of actual evaporation may still be small due to little vegetation, little rainfall and soils that easily dry up after snowmelt. potential evaporation can be determined by measurements or by computations based on climatic data. actual evaporation is usually computed as a fi xed percentage of potential evaporation or as a function of potential evaporation and soil moisture conditions. it may also be computed as a residual term in a water balance computation. storage change the most signifi cant storage components generally considered in the water balance calculations are: ∆m = ∆ms + ∆mg + ∆ml + ∆mr , (2) where ∆ms is change in snow storage, ∆mg is change in glacier storage, ∆ml is change in 166 water balance investigations in svalbard lakes and river storage, ∆mr is a residual term, including change in soiland groundwater storage. snow storage, lake and river storage and the residual term will normally show limited variations on a seasonal time scale. glacier storage, however, normally show variations over a much longer time scales and the ∆mg term may become very signifi cant over a period of a few years. if the water balance calculation is done for a long time period (several years) most of these terms can usually be neglected, with the exception of ∆mg. also, if the water balance is done for hydrological years (e.g. 1/9–31/8 or 1/10–30/9) the storage terms (except ∆mg) can usually be neglected. for shorter time steps (month, week, day) all the storage terms must be included in the calculation, which complicates the calculations considerably. previous work some of the elements in the water balance have been measured for a long time in svalbard. precipitation measurements have been made by the norwegian meteorological institute from 1911 in green harbour, from 1916 in longyearbyen and from 1950 in ny-ålesund (førland et al. 1997b). glacier mass balance measurements started 1966 at brøggerbreen (j. o. hagen, pers. comm 2002), while the fi rst known systematic runoff measurements in svalbard were started in bayelva close to ny-ålesund from 1974 (repp 1988a, b). regular and continuous runoff measurements have been operated by the norwegian water resources and energy directorate since 1989 in bay elva. later, regular runoff measurements have been established in three other catchments: endalen/ isdammen and de geerdalen close to longyearbyen, and in londonelva near ny-ålesund. evaporation measurements are almost non-existent, but a few measurements were done by the foundation for technical and industrial research at the norwegian institute of technology (sintef) in ny-ålesund in 1992 and 1993 as part of the land arctic physical processes (lapp) project (institute of hydrology et al. 1999). the fi rst known water balance study in svalbard was done near kings bay in 1968 (geoffray 1968). data from repp’s studies in bayelva were used by bruland (1991) in an attempt to establish the water balance and calibrate hydrological models in svalbard. these data were also used by hagen & lefauconnier (1993). some other river fl ow measurements have been reported by russian scientists (gokhman & khodakov 1986) and polish scientists (pulina et al. 1984). none of these studies included a complete water balance computation. jania & pulina (1994) reported on the results from several polish research projects in svalbard, and summarized the results in tables for water balance and chemical denudation in the weren skioldbreen basin for one hydrological year (1979/80) and for several unidentifi ed basins in the horn sund area. the main results are summarized in table 1. water balance computation for catchments in svalbard based on norwegian studies was presented at the northern research basins meeting in ny-ålesund in 1994 (killingtveit et al. 1994). this study was based on the observations initiated by the norwegian national committee for hydrology from 1991 to 1993 in the three catchments—bayelva, de geerdalen and endalen/ isdammen. in this paper the results from a literature search were also reported, but no other studies beyond those already noted could be found. several studies have been done concerning winter water balance and possible groundwater fl ow to tvillingvatnet, near ny-ålesund, and isdammen, near longyearbyen. these are summarized in the section on groundwater runoff. sand & bruland (1999) presented the water balance for the bayelva, londonelva and de geereltable 1. water balance results from polish research projects in svalbard reported by jania & pulina (1994). glaciated catchments permafrost basins pa 1070 1340 mm/year 800 mm/year qs 1680 1920 mm/year 710 mm/year ea 90 mm/year 90 mm/year ∆mg 670 700 mm/year 0 mm/year table 2. water balance results from catchments in spitsbergen reported by sand & bruland (1999). bayelva londonelva de geerdalen pa (mm/year) 968 595 478 ea (mm/year) 46 100 108 ∆mg (mm/year) –456 0 –21 qs (mm/year) 1053 411 525 ε (mm/year) –7 118 –134 167killingtveit et al. 2003: polar research 22(2), 161–174 va catchments for the years 1991 to 1998 (see table 2). for years when snow survey data existed they determined the areal winter precipitation based on the snow survey data rather than measurement of precipitation. for other years, the areal precipitation was estimated from precipitation measurements only. a recent work (mercier 2001) includes a summary from a large number of studies of geomorphology, glaciology and hydrology in svalbard, including studies of the components in the hydrological balance (water balance) for austre lovénbreen in kongsfjorden and for a 0.1 km2 non-glaciated area near zeppelinerfjellet near ny-ålesund. some of the results from this report are included in subsequent sections. catchments selected for water balance study in this paper, data from the three catchments with the best data coverage—bayelva, de geerdalen and endalen—will be used. a brief description of the different observation data (runoff, precipitation, evaporation and glacier balance) is given in the following sections. the location of the catchments and a simplifi ed map of each catchment is shown in fig. 2. the area–elevation distribution within each catchment (hypsographic curve) is shown in fig. 3. a summary of the most important data for each catchment is given in table 3. runoff measurements–stations and records surface runoff—bayelva. runoff measurements in bayelva started in 1974 (repp 1979). these measurements ended in 1978, but were resumed in 1990 as part of an initiative taken by the norwegian national hydrological committee in 1987. measurements during the fi rst year are considered unreliable due to an unstable river bed. in 1988 the river profi le was stabilized by a concrete crump-type weir and a permanent and stable rating curve could be established (skretteberg 1992). the main operational problem now is caused by snow blocking the weir at the start of the snowmelt season, leading to errors in calculation of river discharge. this is corrected for as far as possible, but the resulting accuracy is not precisely known. surface runoff—de geerdalen. in the autumn of 1990 a second runoff station was established in de geerdalen. the station is located in a narrow gorge with stable bedrock profi le close to the outlet of the river, at hyperittfossen (fig. 2). the station has been in routine operation since summer 1991. the main operational problems here are related to ice and snow blocking in the narrow gorge. surface runoff—isdammen/endalen. the fi rst station was established early in the summer of 1992, in the outlet from isdammen, the water supply reservoir for longyearbyen (fig. 2). here, the main operational problems were caused by uncertain rating curves and ungauged leakage in the outlet structure. later, the station was reestablished in endalselva, upstream of a road culvert close to the inlet to isdammen. at this site bottom ice build-up in the river profi le seems to be the main operational problem, possibly also some leakage outside the main culvert. there is some uncertainty in the drainage area for these catchments, since the glacier bogerbreen may also have some drainage to another catchment. annual runoff for hydrological years for the three catchments is shown in table 4. average monthly runoff (mm/month) is shown in table 5 and the seasonal distribution of the runoff over the year is shown in fig. 4. it is evident from fig. 4 that runoff occurs mainly in june–september, with maximum runoff occurring in july. the runoff is dominated by snowmelt in june and july, while in august and september the runoff mainly comes from rainfall and glacial melt. the high percentage of glaciers in the bayelva catchment gives a relatively higher runoff in august and september than in the two other catchments. groundwater runoff. due to the permafrost there is usually no fl ow in groundwater below the table 3. data for the three catchments bayelva, de geerdalen and isdammen/endalen. the minimum elevation is where the runoff gauging station is located area (km2) elevation (m a.s.l.) % glaciersmin. average max. bayelva 30.9 4 265 742 55 de geerdalen 79.1 40 410 987 10 isdammen 34.4 3 427 1015 17 endalselva 28.8 4 427 1015 20 168 water balance investigations in svalbard active zone (1 2 m) and therefore probably no groundwater fl ow directly to the sea. exceptions may be groundwater fl ow from recharge areas under temperate glaciers and discharge through taliks under lakes or directly to the sea. speculations concerning possible groundwater infl ow to the water supply reservoirs for ny-ålesund and longyearbyen (winther 1994) spurred special studies of the winter water balance for these reservoirs and their catchments. for tvillingvatnet (ny-ålesund) there was previously documented winter infl ow from groundwater in the 1920s. this groundwater fl ow was probably generated by recharge below the temperate basal part of the glacier austre brøggerbreen (haldorsen & heim 1999). recent studies during 1990s (sandsbråten 1995) did not confi rm these results, but fl ow may have been reduced due to reduced infi ltration area as the glacier has retreated signifi cantly (haldorsen & heim 1999). groundwater recharge in the isdammen reservoir near longyearbyen have been postulated as a possibility. studies during the winter 1999/ 00 have not lead to conclusive evidence of any groundwater infl ow (klungland 2000). there are no data to confi rm or exclude the possibility of groundwater fl ow directly to the sea in svalbard. halvorsen & heim (1999) did a detailed investigation along kongsfjorden in the ny-ålesund area but could not fi nd any indications of springs discharging along the coast or into the fjord. therefore, in the water balance calculation presented here, it is assumed that no signifi cant groundwater fl ow exists into or from the three catchments studied. fig. 4. seasonal variations in runoff for the three selected catchments. monthly averages computed for the observation period. table 5. seasonal variation in runoff, mm/month, average for years 1990–2001. runoff (mm) bayelva de geerdalen endalen january 0 0 0 february 0 0 0 march 0 0 0 april 0 0 0 may 0 1 0 june 201 164 109 july 437 233 247 august 317 106 114 september 111 33 34 october 4 4 0 november 0 0 0 december 0 0 0 table 4. annual runoff (mm/year) for the three catchments. hydrol. year bayelva de geerdalen endalen 1990 1288 573 1991 947 489 1992 1097 641 486 1993 1292 429 596 1994 962 481 1995 1005 463 429 1996 1012 596 555 1997 1008 605 608 1998 1061 472 611 1999 1227 593 534 2000 877 586 2001 1316 573 average 1091 539 545 169killingtveit et al. 2003: polar research 22(2), 161–174 precipitation measurements stations and data records bayelva. there are no regular precipitation measurements in the bayelva catchment, but the meteorological station in ny-ålesund is located quite close to the catchment. here, regular precipitation measurements have been made since 1950. in addition, various studies concerning precipitation correction and precipitation distribution have been done. one of the most interesting is a study of precipitation distribution and precipitation gradients carried out by the norwegian meteorological institute (førland et al. 1997a). in other studies precipitation has also been estimated indirectly through snow measurements and glacier mass balance measurements within the catchment. these measurements are later used to establish precipitation–elevation gradients. de geerdalen. there are no regular precipitation measurements in the catchment and the closest meteorological station is located at svalbard airport, about 20 km south-west of the valley de geerdalen. a number of precipitation stations were operated for a few years in the early 1990s as part of the fi rst water balance studies initiated by the norwegian hydrological committee (killingtveit et al. 1994). a network of snow measurement stations has also been operated since 1991, making it possible to estimate winter precipitation indirectly (tveit & killingtveit 1994). these measurements have been used to estimate precipitation–elevation gradients in the catchments (killingtveit et al. 1994). isdammen/endalen. there are no regular precipitation measurements in the catchment and the closest meteorological station is located at svalbard airport, about 10 km west of isdammen. a number of precipitation stations were operated a few years in the early 1990s as part of the fi rst water balance studies. these measurements have been used to estimate precipitation–elevation gradients in the catchments (killingtveit et al. 1994). annual measured precipitation in ny-ålesund and svalbard airport is shown for the hydrological years 1990/91 to 2000/01 in table 6. average (normal) monthly precipitation for the two stations is shown in table 7. areal precipitation precipitation correction factors based on previous studies from svalbard (repp 1979; hagen & lefauconnier 1993, 1996; tveit & killingtveit 1994; hanssen-bauer et al. 1996; sand et al. 2003) and other relevant studies in other arctic catchments were used in this water balance calculation, leading to an average correction of 1.15 for rainfall and 1.65 for snow precipitation for ny-ålesund data and slightly higher values (1.15 and 1.75) for svalbard airport data. in these water balance computations a gradient of 15 %/ 100 m was selected for the isdammen/endalen and bayelva catchments, and 20 %/100 m for de table 6. annual precipitation data for stations at ny-ålesund and svalbard airport (mm/year). calender year ny-ålesund svalbard airport 1990 479 157 1991 502 257 1992 381 194 1993 674 262 1994 385 220 1995 256 159 1996 547 234 1997 390 217 1998 248 92 1999 348 187 2000 519 203 2001 487 185 average 431 196 table 7. precipitations averages (mm/month) for the period 1961–1990 based on data from stations at ny-ålesund and svalbard airport. ny-ålesund svalbard airport january 32 15 february 36 19 march 45 23 april 23 11 may 18 6 june 18 10 july 28 18 august 38 23 september 46 20 october 37 14 november 33 15 december 31 16 sum 385 190 170 water balance investigations in svalbard geerdalen. observed precipitation was fi rst corrected for catch errors and then for elevation gradients, giving the average (areal) precipitation for each of the catchments. for catch errors the rain correction factor was applied for months with air temperature > 0 °c and snow correction factor for months with air temperature < 0 °c. the results of these computations are given as annual values in table 8 for the bayelva catchment. the same computations were done for the two other catchments. this is the fi nal and total precipitation input to the three catchments and it is used in the subsequent water balance computation. evaporation measurements evaporation measurements have been and remain very scarce in svalbard. a survey by bruland (1991) found only one reference to previous measurements in svalbard. based on this observation and a few data from other arctic sites, bruland estimated an actual average annual evaporation of 100 mm/year. this value was later also used by hagen & lefauconnier (1993, 1996). in the fi nal report from the lapp project (institute of hydrology et al. 1999) the use of evaporation data in water balance computations is discussed with reference to hagen & lefauconnier (1993) and killingtveit et al. (1994). the value of 100 mm/year is used, the report stating that “still, no better estimate exists, and we have used the same value in our study” (p. 38). net evaporation from glaciers was assumed to be 0. jania & pulina (1994) used 90 mm/year in their water balance calculations. this value seems to be based on calculations from meteorological data “due to diffi culties in taking measurements (a large error range is likely)” (p. 62). to improve evaporation estimates, a class a evaporation pan was installed in ny-ålesund in 1992 and operated by sintef. some early results from the measurements are reported in killingtveit et al. (1994). the annual pan evaporation was estimated to 166 mm, based on pan measurements and some computed values where a regression equation between evaporation and air temperature was used to infi ll data gaps. the average actual evaporation from non-glaciated catchments was estimated to 120 mm/year in the ny-ålesund area, at an elevation of 10 m a.s.l. mercier (2001) reports computed potential evaporation for the years 1969–1995, based on both the turc and the penman formulas. average computed values were 200 mm/year (penman) and 51 mm/year (turc). the large deviation between the two methods is discussed and it seems that most confi dence is placed on the results from the turc formula. in this study a computation of potential evaporation as a function of air temperature was used. this function was calibrated by regression analysis using sintef’s evaporation observations in ny-ålesund and air temperature data from nyålesund. the computed average annual potential evaporation for the 12-year period 1989–1991 was 138 mm/year for an area close to sea level in ny ålesund, computed from air temperature data and assuming a pan coeffi cient of 1. evaporation from snow or glaciers is not included. this value can be compared to data from axel heiberg island (80° n) where ohmura (1982) found an average evaporation of 138 mm/year. this value also included an estimated value of 20 mm/year of sublimation from snow. using the regression model and observed air temperature data the average evaporation from glacier-free areas could be computed for each year, using an average lapse rate of –0.6 °c/ 100 m. the results were 80 mm/year in bayelva and 82 mm/year in de geerdalen and endalen— about 50 mm/year less than potential evaporation close to sea level. net annual evaporation from glaciers is assumed to be 0, as in previous studies in svalbard (hagen & lefauconnier 1993, 1996; institable 8. areal precipitation calculation in bayelva (mm/ year). hydrological year observed precip. catch correction elevation correction areal precip. 1990/91 472 252 293 1016 1991/92 420 182 243 845 1992/93 396 213 247 856 1993/94 678 369 424 1472 1994/95 169 84 102 355 1995/96 648 348 403 1398 1996/97 312 157 190 659 1997/98 242 148 158 548 1998/99 380 175 225 780 1999/00 387 148 217 751 2000/01 582 207 320 1109 average 426 207 256 890 171killingtveit et al. 2003: polar research 22(2), 161–174 tute of hydrology et al. 1999). this assumption can be questioned, but it has not been possible to fi nd better estimates from studies in svalbard. there will probably be some losses by sublimation from dry snow and blowing snow but also some input by sublimation on ice during summer months. the net balance between losses and gains by sublimation on glaciers in svalbard is probably small but cannot be verifi ed yet. more studies need to be done. if such errors exist, positive or negative, it will add up in the error term in the water balance. using these data and the percent of glaciated area for each catchment (table 3), the following values for average annual actual evaporation were computed for the catchments: bayelva, catchment average 80 mm/year * 0.45 = 38 mm/year at 265 m a.s.l. de geerdalen, catchment average 82 mm/year * 0.90 = 72 mm/year at 410 m a.s.l. endalen, catchment average 82 mm/year * 0.80 = 66 mm/year at 427 m a.s.l. storage terms if the water balance is computed on an annual basis and for hydrological years, most of the storage terms in eq. (2) can be neglected. using a hydrological year from 1/10 to 30/9, we can assume that changes in snow storage, lakes, ground water and soil moisture from one year to another can be neglected. lake storage is only important in endalen/ isdammen but here the lake level has been measured and the lake is always fi lled to the same (maximum) level at the beginning of the winter season. due to the deep permafrost there is no groundwater recharge from the surface except possibly below some of the glaciers. such groundwater recharge has been not been identifi ed in these three catchments, though there may be some small recharge under vestre lovénbreen. (haldorsen & heim 1999). if any recharge exists it is probably very small; there are no indications of substantial changes from year to year. there are, to our knowledge, no indications that water content in the active layer changes signifi cantly from year to year. however, no measurements are available to prove this assumption. theoretically, a very dry summer and autumn could dry out the soil moisture in the active layer, leaving a deficit that would fi ll up next spring. also, there are no wetlands or icings that could store and “carry over” water from one year to another. seasonal snow cover is always melted before the end of september and new snow cover usually starts to build up from october. therefore, it seems acceptable to assume that all these storage terms can be neglected, except possibly some changes in soil moisture in the active layer. since we have no data to compute such changes, the possible errors will contribute to the error term in the water balance. the change in glacier mass balance from year to year is very important and must to be included in the water balance. mean annual net mass balances for a number of spitsbergen glaciers have been studied for many years, some back to 1951. at austre brøggerbreen, the annual mass balance has been studied since 1967, at longyearbreen from 1977 to 1982 table 9. glacier mass balance for austre brøggerbreen (in m) for hydrological years 1974/75 to 2000/01. hydrological year winter summer total 1974/75 0.78 –1.09 –0.31 1975/76 0.72 –1.17 –0.45 1976/77 0.76 –0.87 –0.11 1977/78 0.75 –1.31 –0.56 1978/79 0.77 –1.48 –0.71 1979/80 0.75 –1.27 –0.52 1980/81 0.46 –1.01 –0.55 1981/82 0.64 –0.68 –0.04 1982/83 0.70 –0.97 –0.27 1983/84 0.69 –1.42 –0.73 1984/85 0.93 –1.48 –0.55 1985/86 0.98 –1.3 –0.32 1986/87 0.82 0.6 0.22 1987/88 0.61 –1.13 –0.52 1988/89 0.56 –1.01 –0.45 1989/90 0.75 –1.41 –0.66 1990/91 0.92 0.79 0.13 1991/92 0.69 –0.89 –0.1 1992/93 0.54 –1.57 –1.03 1993/94 0.79 –0.95 –0.16 1994/95 0.56 –1.34 –0.78 1995/96 0.78 –0.95 –0.17 1996/97 0.50 –1.12 –0.88 1997/98 0.65 –1.78 –1.13 1998/99 0.51 –0.87 –0.36 1999/00 0.41 –0.51 –0.11 2000/01 – – –0.45 172 water balance investigations in svalbard and at bogerbreen from 1975 to 1986 (j. kohler, pers. comm. 2002). annual results are given in table 9. the average annual mean net balance during the observational period is given below: brøggerbreen 1967–2002, –450 mm/year bogerbreen 1975–1986, –430 mm/year longyearbreen 1977–1982, –550 mm/year for water balance computations in bayelva we used the changes measured at brøggerbreen directly. for the water balance computations in the de geerdalen and in endalen/isdammen there exist no glacier mass balance data for the glaciers in the catchments for the period when runoff has been measured. since the bogerbreen and longyearbreen glaciers are much closer to these catchments than brøggerbreen, we assumed that the bogerbreen and longyearbreen glaciers provide better information on glacial mass balance than brøggerbreen. in lieu of direct glacier mass balance data in de geerdalen and endalen/ isdammen, we used annual changes measured at brøggerbreen as an index of glacier mass balance, scaled by the difference between the glaciers bogerbreen and longyearbreen and brøggerbreen during the overlapping measurement periods. the computed scaling factor is 1.06, i.e. changes in glacier storage in de geerdalen and endalen are computed as 1.06 times changes at brøggerbreen, per unit area. water balance calculation the water balance for bayelva was calculated annually from data given in tables 4, 8 and 9. the results are summarized in table 10. the water balance for de geerdalen and endalen/isdammen was calculated similarly and the results are summarized as average for the whole computational period in table 11, together with the results from bayelva. discussion of results the average water balance is good for all three catchments, with an average error term (imbalance) close to 0. there are, however, large deviations in some years which cannot easily be explained. a correlation analysis shows that there is still a strong correlation between the annual error term and winter precipitation. this indicates that the residual errors are probably related to problems of precipitation correction and areal precipitation computations. the results show very clearly the large difference between observed precipitation and areal precipitation computed within the catchments. the observed precipitation has to be multiplied by a factor on the order of 2 to compensate for errors in measurements and non-representative locations. the glacial mass balance term also makes a large contribution to the water balance and possible errors here will easily contribute signifi cantly to the errors in some years. the evaporation is usually the most uncertain term in water balance computations. the results here cannot verify or disprove the evaporation estimates since the error terms in many years is on the same order of magnitude as the evaporation. comparing our results with the results reported by jania & pulina (1994), both the measured runoff and precipitation estimates are consideratable 10. water balance for the de geerdalen catchment in hydrological years 1990/91 to 2000/01: pwinter + psummer + ∆glaciers – q – e = ε. all terms are in mm. hydrological year pwin psum ∆glaciers q e ε 1990/91 504 176 -14 573 70 23 1991/92 329 270 11 489 69 52 1992/93 503 134 109 641 93 12 1993/94 455 254 17 429 45 252 1994/95 224 115 83 481 77 –136 1995/96 561 189 18 463 53 252 1996/97 347 197 93 596 50 –8 1997/98 254 68 120 605 103 –266 1998/99 218 232 38 472 69 –54 1999/00 316 208 12 593 65 –122 2000/01 288 180 48 586 95 –166 average 364 184 49 539 72 –15 std. dev. 122 60 45 72 19 162 table 11. water balance for all catchments – annual average for hydrological year (pwinter + psummer + ∆glaciers – q – e = ε. all terms are in mm. catchment pwin psum ∆glaciers q e ε std ε bayelva 597 277 245 1050 37 31 230 de geerdalen 364 184 49 539 72 -15 162 endalen/ isdammen 321 158 101 545 66 -14 106 173killingtveit et al. 2003: polar research 22(2), 161–174 bly lower in this study. it should be kept in mind the catchments investigated by jania & pulina (1994) are all located in the hornsund area, in southern spitsbergen, while our catchments are located in the central and north-western parts of the island. sand et al. (2003) did a study of regional snow distribution on spitsbergen which indicates that the hornsund area receives approximately twice as much precipitation during the snow accumulation period (october–may) as the central region. so far, the results from the water balance studies carried out in svalbard have not been evaluated against water balance studies from other regions of the arctic. however, the results from svalbard will be part of a recently initiated study which will be an intercomparison of water balance in arctic experimental watersheds (d. l. kane, pers. comm 2003). further studies—recommendations the results show that the calculated water balance in svalbard still cannot be considered good enough to assess the individual components of the hydrological cycle with fair accuracy. even though the average balance (error term) in the three catchments is close to zero, errors in individual years are still considerable. this indicates that it is still necessary to improve data collection and possibly also correction methods, in particular for precipitation and glacial net balance. we recommend more detailed investigations concerning precipitation distribution, in particular the distribution during winter, when most of the precipitation falls. snow measurements can be used to study amount and distribution of seasonal snow. such data can be useful both to improve methods for precipitation correction and methods for computing areal precipitation in svalbard. even if evaporation is not a dominant factor in the water balance, it would be very useful to improve the data base and we recommend that regular measurements should be established to acquire more precise data and to study seasonal and interannual variations in evaporation. also, it would be useful to study and collect data on the evaporation from snow since this has not yet been studied in svalbard. acknowledgements.—we would like to thank all those who have supplied data and information concerning previous studies and reports. in particular we thank the norwegian meteorological institute for supplying all meteorological data, and the norwegian water resources and energy directorate for supplying runoff data and information concerning quality of runoff data. we also thank to jack kohler at the norwegian polar institute and jon ove hagen at the university in oslo for providing information about glacier mass balance for a number of glaciers. references bogdanova, e. g. 1968: estimate of the reliability of the characteristics of the shortage in solid precipitation due to wind. soviet hydrology. selected papers 2 1968, 139–146. washington, d. c.: american geophysical union. bruland, o. 1991: vassbalanse og avlaupsmodellar i permafrostområder. (water balance and runoff in permafrost areas). thesis d-1991-28. dept of hydraulic and environmental engineering, university of trondheim. førland, e. j., allerup, p., dahlström, b., elomaa, e., jónsson, t., madsen, h., perälä, j., rissanen, p., vedin, h. & vejen, f. 1996: manual for operational correction of nordic precipitation data. rep. 24/96. oslo: norwegian meteorological institute. førland, e., hanssen-bauer, i. & nordli, p. ø. 1997a: orographic precipitation at the glacier austre brøggerbreen, svalbard. klima 02/97. oslo: norwegian meteorological institute. førland, e., hanssen-bauer, i. & nordli, p. ø. 1997b: climate statistics & longterm series of temperature and precipitation at svalbard and jan mayen. klima 21/97. oslo: norwegian meteorological institute. geoffray, h. 1968: etude du bilan hydrologique et de l’érosion sur un bassin pertiellement englacé, spitsberg, baie du roi, 79° lat. nord. (a study of water balance and erosion in a partly glaciated basin, spitsbergen, kings bay, 79° n.). thesis, university of rennes. gokhman, v. v. & khodakov, v. g. 1986: hydrological investigations in the mimer river basin, svalbard in 1983. polar geogr. geol. 10, 309–316. hagen, j. o. & lefauconnier, b. 1993: reconstructed runoff from the high arctic basin bayelva in svalbard based on mass-balance measurements. in k. sand (ed.): polar hydrologi. rapport fra forskermøte i trondheim 29–30 mars 1993. (report from research meeting in trondheim 29–30 march 1993.) sintef rep. stf60 a93081. pp. 25– 38. trond heim: norwegian institute of technology. hagen, j. o. & lefauconnier, b. 1996: reconstructed runoff from the high arctic basin bayelva based on mass-balance measurements. nord. hydrol. 26, 285–296. haldorsen, s. & heim, m. 1999: an arctic groundwater system and its dependence upon climate change: an example from svalbard. permafrost periglacial process. 10, 137–149. hanssen-bauer, i., førland, e. & nordli, p. ø. 1996: measured and true precipitation at svalbard. klima 31/96. oslo: norwegian meteorological institute. institute of hydrology, institute of terrestrial ecology, finnish meteorological institute, finnish environmental institute, foundation for technical and industrial research 174 water balance investigations in svalbard (norwegian institute of technology), institute of geography & university of copenhagen 1999: final report lapp: land arctic physical processes. available on the internet at http://www.nwl.ac.uk/ih/www/research/iresearch.html. jania, j. & pulina, m. 1994: polish hydrological studies in spitsbergen, svalbard: a review of some results. in k. sand & å. killingtveit (eds.): proceedings of the 10th international northern research basins symposium and workshop, spitsbergen, norway. pp. 47–76. sintef rep. 22 a96415. trondheim: norwegian institute of technology. killingtveit, å., petterson, l.-e. & sand, k. 1994: water balance studies at spitsbergen, svalbard. in k. sand & å. killingtveit (eds.): proceedings of the 10th international northern research basins symposium and workshop, spitsbergen, norway. sintef rep. 22 a96415. pp. 77–94. trondheim: norwegian institute of technology. klungland, k. o. 2000: winter water balance for isdammen, svalbard. thesis, stavanger university college and university centre on svalbard. larsson, l. w. & peck, e. l. 1974: accuracy of precipitation measurements for hydrological modelling. water resour. res. 10, 857–863. mercier, d. 2001: le ruissellement au spitsberg. (runoff on spitsbergen.) clermont-ferrand, france: blaise pascal university press. ohmura, a. 1982: evaporation from the surface of the arctic tundra on axel heiberg island. water resour. res. 18, 291– 300. petterson, l.-e. 1994: the hydrological regime of spitsbergen, svalbard. in k. sand & å. killingtveit (eds.): proceedings of the 10th international northern research basins symposium and workshop, spitsbergen, norway. sintef rep. 22 a96415. pp. 95–107. trondheim: norwegian institute of technology. pulina, m., rereyma, j., kida, j. & krewczyk, w. 1984: characteristics of the polar hydrological year 1979/80 in the basin of the werenskiold glacier, sw spitsbergen. pol. polar res. 5, 165–182. repp, k. 1979: breerosjon, glasiohydrologi og materialtransport i et høyarktisk miljø, brøggerbreene, vest-spitsbergen. (glacial erosion, glacial hydrology and sediment transport in a high arctic basin, brøggerbreen, west spitsbergen.) msc thesis, university of oslo. repp, k. 1988a: the hydrology of bayelva, northwest spitsbergen. in t. thomsen et al. (eds.): proceedings of the 7th northern research basins symposium/workshop. may 25june 1 1988. illulissat, greenland. pp. 105–114. copenhagen: danish scoeity for arctic technology. repp, k. 1988b: the hydrology of bayelva, spitsbergen. nord. hydrol. 4, 259–268. sand, k. & bruland, o. 1999: water balance of three high arctic river basins in svalbard. in j. elíasson (ed.): proceedings of the 12th international northern research basins symposium and workshop. reykjavik, kirkjubæjarklaustur and höfn, iceland, august 23–27, 1999. pp. 270– 283. reykjavik: engineering institute, university of iceland. sand, k., winther, j.-g., maréchal, d., bruland, o. & melvold, k. 2003: regional variations of snow accumulation on spitsbergen, svalbard, 1997–99. nord. hydrol. 34, 17– 32. sandsbråten, k. 1995: vannbalanse i et lite arktisk nedbørfelt, tvillingvatn, svalbard. (water balance in a small arctic catchment, tvillingvann, svalbard.) repo. 43. dept. of geography, university of oslo. sevruk, b. 1982: methods of correction for systematic error in point precipitation measurement for operational use. wmo oper. hydrol. rep. 21. wmo-no 589. geneva: world meteorological organization. skretteberg, r. 1992: the establishment of gauging stations under arctic conditions—the svalbard experience. in t. d. prowse et al. (eds.): proceedings of the 9th international northern research basins symposium and workshop, canada 1992. nhri symposium no. 10, vol. 2. pp. 509–518. saskatoon: national hydrology research institute. strutzer, l. r. 1965: principal shortcomings of methods of measuring atmospheric precipitation and means of improving them. soviet hydrology, selected papers, 1 1965, 21– 35. american geophysical union. tveit, j. & killingtveit, å. 1994: snow surveys for studies of water budget on svalbard 1991–1994. in k. sand & å. killingtveit (eds.): proceedings of the 10th international northern research basins symposium and workshop, spitsbergen, norway. sintef rep. 22 a96415. pp. 489– 509. trondheim: norwegian institute of technology. winther, j.-g. 1994: polar hydrology—svalbard. revision of the original r&d programme. in k. sand & å. killingtveit (eds.): proceedings of the 10th international northern research basins symposium and workshop, spitsbergen, norway. sintef rep. 22 a96415. pp. 1–22. trondheim: norwegian institute of technology. winther, j.-g., bruland, o., sand, k., killingtveit, å. & marechal, d. 1998: snow accumulation distribution on spitsbergen, svalbard in 1997. polar res. 17, 155–164. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /all /binding /left /calgrayprofile (dot gain 20%) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages true /colorimagedownsampletype /bicubic /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages true /grayimagedownsampletype /bicubic /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /fra <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> /enu (use these settings to create pdf documents with higher image resolution for improved printing quality. the pdf documents can be opened with acrobat and reader 5.0 and later.) /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308000200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e30593002537052376642306e753b8cea3092670059279650306b4fdd306430533068304c3067304d307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e30593002> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <feff004200720075006b00200064006900730073006500200069006e006e007300740069006c006c0069006e00670065006e0065002000740069006c002000e50020006f00700070007200650074007400650020005000440046002d0064006f006b0075006d0065006e0074006500720020006d006500640020006800f80079006500720065002000620069006c00640065006f00700070006c00f80073006e0069006e006700200066006f00720020006200650064007200650020007500740073006b00720069006600740073006b00760061006c0069007400650074002e0020005000440046002d0064006f006b0075006d0065006e00740065006e00650020006b0061006e002000e50070006e006500730020006d006500640020004100630072006f0062006100740020006f0067002000520065006100640065007200200035002e00300020006f0067002000730065006e006500720065002e> /sve <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> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice no job name decrease of lichens in arctic ecosystems: the role of wildfire, caribou, reindeer, competition and climate in north-western alaskapor_113 433..442 kyle joly,1,2 randi r. jandt3 & david r. klein4 1 national park service, gates of the arctic national park and preserve, 4175 geist road fairbanks, ak 99709, usa 2 department of biology and wildlife, 211 irving 1, university of alaska fairbanks, fairbanks, ak 99775, usa 3 bureau of land management, alaska fire service, 1541 gaffney road, fort wainwright, ak 99703, usa 4 institute of arctic biology, university of alaska fairbanks, p.o. box 757000, fairbanks, ak 99775, usa abstract we review and present a synthesis of the existing research dealing with changing arctic tundra ecosystems, in relation to caribou and reindeer winter ranges. whereas pan-arctic studies have documented the effects on tundra vegetation from simulated climate change, we draw upon recent long-term regional studies in alaska that have documented the actual, on-the-ground effects. our review reveals signs of marked change in arctic tundra ecosystems. factors known to be affecting these changes include wildfire, disturbance by caribou and reindeer, differential growth responses of vascular plants and lichens, and associated competition under climate warming scenarios. these factors are interrelated, and, we posit, unidirectional: that is, they are all implicated in the significant reduction of terricolous lichen ground cover and biomass during recent decades. lichens constitute the primary winter forage for large, migratory caribou and reindeer herds, which in turn are a critical subsistence resource for rural residents in alaska. thus, declines in these lichens are a major concern for rural people who harvest caribou and reindeer for subsistence, as well as for sport hunters, reindeer herders, wildlife enthusiasts and land managers. we believe a more widely distributed and better integrated research programme is warranted to quantify the magnitude and extent of the decline in lichen communities across the arctic. keywords climate warming; disturbance; fire; grazing; lichens; rangifer tarandus. correspondence kyle joly, national park service, 4175 geist road, fairbanks, ak 99709, usa. e-mail: kyle_joly@nps.gov doi:10.1111/j.1751-8369.2009.00113.x climate warming is predicted to cause unprecedented change in the future (parry et al. 2007). rapid and dramatic changes in both terrestrial and aquatic ecosystems were already evident throughout much of the arctic several years ago (symon et al. 2005). the arctic is now experiencing the warmest temperatures it has seen over the past 400 years, and the rate of temperature rise is predicted to increase (hinzman et al. 2005; symon et al. 2005). these climatic changes will have, and indeed are already having, a dramatic effect on the flora and fauna of the arctic. a comprehensive review of the effects of climate change on the winter range of reindeer (rangifer tarandus tarandus) in norway was conducted by heggberget et al. (2002). their review focused on how climate warming could affect the quality, distribution and availability of winter forage, with lichens being of specific interest (heggberget et al. 2002). terricolous (ground-dwelling) lichens are the preferred winter forage, where available, for rangifer populations, with specific species of interest that include cladina mitis, cladina rangiferina, cladina stellaris, cladonia amaurocraea, cladonia gracilis, cladonia uncialis, cetraria cucullata, cetraria ericetorum, cetraria islandica and cetraria nivalis (ahti 1959; scotter 1967; pegau 1968; holleman & luick 1977; thomas & hervieux 1986; thomas & kiliaan 1998; brodo et al. 2001). heggberget et al. (2002) also reviewed the impacts of climate warming on alternative, vascular forage, and the impacts of grazing on lichens, whereas the role of wildfire, uncommon in norwegian reindeer ranges, was only briefly covered. the intent with our review is to build upon past reviews, highlighting the major driving factors altering arctic flora, while focusing on the winter ranges of polar research 28 2009 433–442 © 2009 the authors 433 mailto:joly@nps.gov caribou (rangifer tarandus granti) and reindeer (rangifer, collectively) in alaska. by expanding the scope of the review to include the findings of recent long-term field and experimental studies on changes in the tundra ecosystems in alaska, we believe that the possibility of panarctic changes should be considered. there is strong agreement in climate change models with regards to temperature changes, and the rate of climate warming in alaska is predicted to accelerate (chapin et al. 2005; symon et al. 2005; parry et al. 2007). wildfires, a primary ecosystem driver in the boreal forest regions of alaska, have increased in frequency and extent in recent years (kasischke & turetsky 2006; shulski & wendler 2007). though more common in boreal forest ecosystems, fires do occur within the tundra winter ranges of rangifer (jandt et al. 2008), and are expected to continue to increase in frequency (higuera et al. 2008). although there is little agreement on how the moisture regime will be affected by climate change, it plays an important role in the ecology of the arctic (rouse et al. 1997), especially for lichens. the reliance of lichens on atmospheric moisture and nutrients, and their slow growth, make them vulnerable to the disturbance and environmental changes driven by climate warming and drying. summer warming and drying, with increased evaporative loss, would lead to decreased growth rates in lichens if there was not an increase in precipitation, be it rain, fog or dew. continued climate warming is expected to have a direct impact on lichens in arctic and subarctic plant communities, and to indirectly impact them through industrial development activities (klein & vlasova 1991), leading to concern that declining lichen communities could lead to reduced rangifer populations. rangifer populations are heavily utilized by rural residents in alaska, and are therefore important in their subsistence-dominated economies. caribou are sought after by sport hunters, and are appreciated by wildlife enthusiasts: groups that are important to the broader economy of alaska. because of the importance of lichens in tundra ecosystem dynamics in alaska, investigators have used longterm monitoring studies to understand their response to disturbance factors that affect their presence and distribution within the northern landscape. we highlight four recent long-term studies in this review. on st. matthew island (fig. 1), in the northern bering sea, permanent plots were originally established in 1957, in conjunction with a study of feral reindeer (klein 1968). on the eastern seward peninsula, permanent plots were established in 1981 to monitor caribou grazing pressure and changes in vegetative cover within the core winter range of the western arctic herd (wah; fig. 1; joly, jandt et al. 2007). jandt et al. (2008) monitored post-fire succession from 1981 to 2006 using adjacent, paired burned and unburned transects within the same region. holt et al. (2008) investigated plots on the western seward peninsula: a region used by both caribou and reindeer. twenty-nine reindeer were introduced to st. matthew island in 1944, as an emergency source of human food for personnel at a navigational station that was abandoned only two years later (klein 1968). much of the vegetated portion of the island was initially blanketed with dense lichen mats. the herd faced no predation pressure, and in the absence of humans the reindeer population rapidly increased, reaching 6000 animals in 1963. by that time, the herd had decimated the lichen community, and, in conjunction with severe weather, a population crash occurred during the late winter of 1964 (klein 1968). the population expired shortly after the crash, as no viable males survived that winter, and the island has remained free of reindeer and other large herbivores ever since. lichen re-growth on the island was tracked during subsequent studies (klein 1987; klein & shulski 2009) the wah, alaska’s largest caribou herd, reached a population of nearly 500 000 in 2003 (dau 2005a). it occupies a total range of about 363 000 km2 in northwestern alaska. the centre of the herd’s wintering area lies just east of the seward peninsula, and is dominated by tussock tundra, but also contains extensive areas of boreal forest and alpine ecosystems. the herd is highly migratory, and faces predation from wolves (canis lupus), bears (primarily ursus arctos), other carnivores and golden eagles (aquila chrysaetos). the wah remains an important resource in the subsistence-dominated lifestyle of the people of the region, which emphasizes the need for an increased understanding of caribou–habitat relationships for the effective management and conservation of the herd. in recent years there has been an increased focus on changes in plant community structure within the winter range of the herd, primarily associated with the influences of wildfire and climate change, and their effects on habitat quality for rangifer and other herbivores (racine et al. 1985; racine et al. 1987; sturm et al. 2001; joly et al. 2007; jandt et al. 2008). the role of terricolous lichens, which constitute the majority (60–80%) of the diet of wah caribou in winter (saperstein 1996), in the ecosystem dynamics of tundra and boreal forest habitats, remains poorly understood. reindeer were first introduced to the seward peninsula in 1892 through the efforts of sheldon jackson, then commissioner for education in alaska, for the purpose of providing a stable supply of food for the native inhabitants (stern et al. 1980). reindeer herding on the seward peninsula was at its apex in the 1930s, when more than 100 000 animals were present, but numbers since have loss of lichens in arctic ecosystems k. joly et al. polar research 28 2009 433–442 © 2009 the authors434 greatly declined (stern et al. 1980). with the expansion of the wah in recent decades making herding of reindeer no longer feasible over all but the westernmost portion of the peninsula, the industry has been reduced to less than 10 000 reindeer (dau 2000). studies of the effects of wildfire and grazing by both rangifer species on the seward peninsula have been carried out by holt et al. (2008). wildfire the role of wildfire in boreal forest succession is relatively well studied. in alaska, the burn area correlates strongly with increased summer temperature (duffy et al. 2005). the frequency and extent of wildfires in north american boreal ecosystems have increased in recent decades (kasischke & turetsky 2006). caribou forage lichens are especially vulnerable to being consumed by fire during dry summers (auclair 1983; dunford et al. 2006), because of their growth form and rapid loss of moisture content in response to decreases in relative humidity that proceed a fire front. caribou are known to avoid recently burned areas in the boreal forest: that is, areas burned within the last 50 years (thomas et al. 1996; thomas et al. 1998; joly et al. 2003; dalerum et al. 2007). less is known about the role of fire in arctic tundra ecosystems. fires are relatively uncommon, and are of limited extent, in tundra ecosystems (wein 1976; payette et al. 1989), although they are somewhat more common in the noatak river valley and the seward peninsula (racine et al. 1985; racine et al. 1987)—both are areas within the range of the wah. similarly, the incidence of fires is increasing within the range of the wah (fig. 2; this study). however, a corresponding trend in the acreage burned has not yet been identified, which may be because of improved firefighting capabilities. in 2007, a fig. 1 total annual range of the western arctic caribou herd, shown outlined by the thick, solid black line, within which the dark-grey shaded area is the core winter range, in north-western alaska (courtesy of the alaska department of fish and game). areas shaded black within the range of the herd depict recent burns (< 55 years old) in boreal forest habitats while stippled areas depict burns within tundra habitats, for the period 1950–2007 (courtesy of the alaska fire service). loss of lichens in arctic ecosystemsk. joly et al. polar research 28 2009 433–442 © 2009 the authors 435 single fire burned over 100 000 ha of tundra, making it the largest fire on record north of the arctic circle in alaska (the north-easternmost fire in fig. 1; this study). in addition to the unusual size of this tundra fire, the fact that it burned so late into the season (e.g., late september, when small lakes had already frozen) was remarkable. this fire elicited concern from local rural residents that arctic tundra fires may become an issue in the future. caribou forage lichens are also vulnerable to being consumed by wildfire in tundra habitats, and are a major component of these ecosystems. the response of caribou to burned tundra habitat has received much less attention than in boreal ecosystems. in fact, only one regional study of these effects has been undertaken so far. this recent analysis using satellite telemetry data determined that caribou avoided burned tundra habitat in mid-winter for up to 55 years (joly, bente et al. 2007). in complementary studies, it was shown that the lichen cover in burned tundra areas was less than 5% at 30 or 35 years post-fire (holt et al. 2008; jandt et al. 2008, respectively). this level of lichen cover is not likely to be great enough for caribou to seek it out as foraging habitat (arseneault et al. 1997; joly, jandt et al. 2007). wildfires reduce the abundance of lichens, especially the late-succession fruticose lichens that are the primary caribou forage lichens, for decades in tundra ecosystems (morneau & payette 1989; arseneault et al. 1997; racine et al. 2004; holt et al. 2006; holt et al. 2008; jandt et al. 2008). furthermore, post-fire lichen recovery is taking longer than has been predicted (jandt et al. 2008). the natural resource conservation service forecasted lichen cover of >20% at 10 years post-fire, and of >30% at 20 years post-fire, on the seward peninsula (swanson et al. 1985), whereas lichen cover has remained at under 5% for 20–35 years post-fire on the plots examined by jandt et al. (2008). caribou and reindeer rangifer directly affect lichen abundance through grazing and trampling (ahti 1959; klein 1968, 1982, 1987; pegau 1969; moser et al. 1979; helle & aspi 1983; van der wal et al. 2001; van der wal 2006). these effects can occur at local and regional levels (moser et al. 1979; morneau & payette 1989; arseneault et al. 1997). on st. matthew island, klein (1968, 1987) reported on the population increase and crash of the introduced reindeer, and their impact on the island flora. heavy grazing pressure exerted by reindeer on st. matthew island as the population increased to its peak, without the option for dispersal or movement from the island, resulted in the near total removal of lichens, with few live fragments from which forage lichen species could regenerate (klein & shulski 2009). although lichen cover and biomass recovered somewhat from 1985 to 2005, it was still below historic levels (klein & shulski 2009). lichen biomass on st. matthew island was just 12% of that on neighbouring hall island, which had not been populated by reindeer (klein & shulski 2009). the wah reached a record high population level (490 000 caribou) by 2003, causing the general public and fig. 2 the incidence of reported fires from 1950 to 2007 occurring within the range of the western arctic caribou herd, north-western alaska (compiled from alaska fire service data). the solid black line represents the 5-year moving average, and the dashed grey line is a best-fit trend polynomial. loss of lichens in arctic ecosystems k. joly et al. polar research 28 2009 433–442 © 2009 the authors436 land managers to become concerned about the possibility of deteriorating winter ranges through heavy grazing pressure (dau 2005a). in fact, lichen cover had declined by more than 50% (joly, jandt et al. 2007) on permanent unburned transects in the winter range between 1981 and 2005, coincident with the population rise. joly, jandt et al. (2007) determined that the decline in lichen cover was significantly related to the amount of caribou utilization: 31% of the variation in the decline of lichens was explained by caribou utilization. on the seward peninsula, areas that were heavily grazed by reindeer had lower lichen cover and shorter thallus heights than areas that were lightly grazed (holt et al. 2008). the recovery of lichen communities from heavy grazing by caribou and reindeer can take a few to many decades, depending on the intensity and duration of grazing, past history of grazing, the suite of lichen species present, characteristics of snow cover at the time of use by the caribou or reindeer, and the duration of the growth season and its favourability for lichen growth (pegau 1969; thing 1984; messier et al. 1988; henry & gunn 1990). competition with vascular plants graminoids (grasses and sedges) are known to increase under heavy grazing pressure from reindeer and caribou in lichen-dominated plant communities (klein 1968; thing 1984; post & klein 1999), and are also predicted to increase under global warming scenarios (chapin et al. 1995; walker et al. 2006). these taxa rapidly increased in the wah winter range over a 25-year period, more than doubling their percentage cover (joly, jandt et al. 2007). holt et al. (2008) revealed a strong negative correlation between lichen and graminoid cover. shrub height and cover extent is also expected to increase with climate warming (chapin et al. 1995; van wijk et al. 2003; walker et al. 2006), and studies using aerial photography indicate that shrub expansion is already occurring in arctic and sub-arctic alaska (sturm et al. 2001; tape et al. 2006). dwarf shrub cover has increased by more than 35% in north-western alaska over the past 25 years (joly, jandt et al. 2007). tall shrubs (e.g., alnus spp.) have noticeably increased within the wah winter range, based on time-paired photos (bureau of land management, unpubl. data). vascular plant species compete with lichens for sunlight and available ground surface substrate. this competition can lead to declining lichen cover in arctic tundra ecosystems. these vascular taxa not only directly compete with lichens, but they also alter the snow-melt patterns, which could lead to even greater shrub cover (sturm et al. 2005). although the shrubs may interfere with the winter grazing of lichens by rangifer, the smothering (by shed leaves of deciduous shrubs) and shading effects of the shrubs may be more detrimental to the lichens. the expansion of vascular plants has also come at the expense of some mosses, which have declined by 67% in the wah winter range (joly, jandt et al. 2007). this may prove to be important regionally, as holt et al. (2008) determined that there was a positive correlation between lichen and moss cover. climate change the observed reduction in lichen cover in north-western alaska over the past 25 years cannot be attributed solely to wildfire and the effects of rangifer grazing. the slow rate of the re-establishment of lichens on st. matthew island, and their subsequent growth, has been further retarded by pronounced climate warming in recent decades, with associated atmospheric drying (klein & shulski 2009). in areas that contain high densities of rangifer or other animal populations in summer, atmospheric drying could result in increased damage to lichen communities by trampling (cooper et al. 2001). lichen cover has declined on some unburned seward peninsula transects that have only experienced light caribou grazing (joly, jandt et al. 2007). jandt et al. (2008) also revealed that lichen cover dropped from 20 to 6% on unburned transects with low caribou use. furthermore, the recovery of lichen communities after wildfire has regressed on transects on the seward peninsula over the past decade (jandt et al. 2008). analyses of the implications of climate change on tundra ecosystems as well as experimental warming studies predict that lichens and mosses will be negatively affected as a result of warming and drying (chapin et al. 1995; robinson et al. 1998; cornelissen et al. 2001; van wijk et al. 2003; epstein et al. 2004; hollister et al. 2005; walker et al. 2006; wiedermann et al. 2007), and we posit that recent observations from north-western alaska augment this body of evidence. furthermore, decreases in lichen and moss cover have also been detected on the north slope of northern central alaska between 1984 and 2002 (jorgensen & buchholtz 2003). alternatively, lichens in alpine habitats may benefit from increased temperatures if there is little competition with vascular species (molau & alatalo 1998) and sufficient atmospheric moisture (cooper et al. 2001). the effects of climate change on arctic ecosystems will not, however, be easy to predict, especially changes in the moisture regime (rouse et al. 1997; wookey 2007). snow is a critical factor in determining the accessibility of winter forage for rangifer (heggberget et al. 2002). rangifer prefer to forage in areas where the snow is less hard and shallow (collins & smith 1991). exceptionally deep snow, in conjunction with depleted lichens, was a loss of lichens in arctic ecosystemsk. joly et al. polar research 28 2009 433–442 © 2009 the authors 437 factor in the crash of the reindeer herd on st. matthew island. in the arctic, warming will be especially pronounced during winter (hinzman et al. 2005; symon et al. 2005). warmer winters could be accompanied by increased rain-on-snow events that form ice crusts, or engulf vegetation, at ground level on rangifer winter ranges. within the winter range of the wah, two of these events have been documented, along with the associated caribou die-offs (dau 2005b). interactions wildfire, disturbance by rangifer, competition with vascular plants and climate change all independently act to reduce lichen cover in arctic tundra ecosystems. these factors, however, are also interactive. wildfires consume lichens, but also facilitate rapid increases in shrub and graminoid cover through nutrient release and soil warming (racine et al. 2004; jandt et al. 2008). darker surfaces left by wildfire charring may reduce surface albedo, leading to more melting, which would give competitive advantage to vascular taxa over lichens. deep burns also expose suitable mineral soil seedbeds for the establishment of new shrubs: particularly willows, which have efficient wind-aided seed dispersal. the establishment of new willows (salix pulchra) following fire on the seward peninsula has been documented (racine et al. 2004). greater shrub cover could also reduce the surface albedo, over that of the pre-burn tundra vegetation (chapin et al. 2005). herbivory can also induce fairly rapid changes in tundra plant community structure, both directly and indirectly (thing 1984; arseneault et al. 1997; van der wal 2006; klein & shulski 2009). areas heavily grazed by reindeer had 26% higher vascular plant cover than areas that were lightly grazed (holt et al. 2008). the reduction of lichens by grazing rangifer may also affect the surface albedo and plant community structure, which could lead into a feedback loop with further declines in lichens. climate warming induces change more slowly, and is the most difficult factor to document with field studies. however, longer growing seasons, increased photosynthetic activity and accelerated leaf tissue maturation have all been detected in tundra ecosystems (goetz et al. 2005). climate warming could lead to more dwarf birch (betula nana) across tundra ecosystems in northern alaska (van wijk et al. 2003), which was the primary fuel when this region had significantly more frequent fires (higuera et al. 2008). thus, climate warming may induce changes in shrub species dominance and cover, which, in conjunction with warmer temperatures, could increase fire frequency (higuera et al. 2008). climate warming and summer drought are correlated with more frequent and extensive wildfires in alaska, northern canada and siberia (wein 1976; duffy et al. 2005; mccoy & burn 2005; soja et al. 2007), which could accelerate lichen declines and the potential disappearance of old-growth lichen tussock tundra communities in north-west alaska (rupp et al. 2000), thereby further degrading the caribou winter range (see rupp et al. 2006). the decline in lichen biomass within plant communities that previously had a major lichen component appears to result from the warmer summers of recent decades, which favour vascular plant growth. moreover, the associated dryer conditions at the ground surface inhibit lichen re-growth following either wildfire or moderate to heavy winter grazing by rangifer species. in other words, climate change may extend the lichen regeneration time lines following disturbance by either wildfire or rangifer grazing (gough et al. 2008; jandt et al. 2008; klein & shulski 2009). the negative effects of climate warming on the rangifer winter range may be partially offset by the improved spring forage quality resulting from earlier snowmelt (cebrian et al. 2008). however, as spring forage quality and availability are temperature dependent, whereas caribou migration and calving are cued by changes in day length, a trophic mismatch may arise (post & forchhammer 2008). in west greenland, this trophic mismatch has resulted in decreased calf production and increased calf mortality (post & forchhammer 2008). conclusions our review of the theoretical, experimental and actual outcomes of climate warming reveals a decrease in the extent and biomass of fruticose lichens over recent decades in north-western alaska. our current understanding of the primary factors influencing arctic tundra ecosystems, inclusive of wildfire, grazing by rangifer species, competition with vascular plants and climate change, leads us to conclude that these factors are unidirectional, interrelated and most likely have led to a marked decline in lichens among plant communities at high latitudes across alaska. changes in arctic and sub-arctic lichen communities in alaska may be representative of changes elsewhere in the arctic (shaver & jonasson 1999), with the possible exception of the fennoscandian arctic (callaghan et al. 1999). our review, in concert with others (e.g., heggberget et al. 2002), leads us to question if these changes may well be pan-arctic in nature, and may foreshadow major changes in plant community structure throughout the world’s circumpolar regions. lichens are considered to be critical winter forage for the large, migratory herds of caribou in north america, loss of lichens in arctic ecosystems k. joly et al. polar research 28 2009 433–442 © 2009 the authors438 for the wild reindeer in eurasia, as well as for the semi-domesticated reindeer throughout the arctic, particularly for herds that face predation (white et al. 1981; klein 1982; syroechkovskii 1995; heggberget et al. 2002). thus, the decline of lichens in arctic and sub-arctic plant communities should concern land managers, subsistence and sport hunters, reindeer herders and wildlife enthusiasts. some researchers have postulated that the transition from a lichen-rich winter diet to one dominated by graminoids may not adversely affect rangifer populations (bergerud 1974; heggberget et al. 2002; van der wal 2006). this postulation, however, is based on ad libitum feeding trials with individual animals in captivity (jacobsen & skjenneberg 1975), and extrapolation from higharctic, low-density populations of peary caribou (rangifer tarandus pearyi; thomas & edmonds 1983) and the svalbard caribou (rangifer tarandus platyrhynchus). the latter, in the absence of predators, with little winter snow accumulation and with little need for efficient mobility, acquired morphological, physiological and behavioural adaptations that, unlike other caribou, equip them for winter survival through low energy expenditure, a greater capacity for fat storage, and an increased efficiency in the digestion of graminoids and mosses (tyler 1987). on predator-free, high-arctic islands, low-density populations of rangifer can survive without abundant fruticose lichens (van der wal et al. 2001; heggberget et al. 2002). lichens, as a component of the winter diet of the continental wah, have declined during the past decade, with corresponding increases in graminoids (joly, cole et al. 2007). therefore, the wah may serve as a test case for assessing the importance of lichens for large, migratory caribou herds that face predation. declining recruitment in the herd (dau 2005a) concurrent with the decline in lichens on the landscape and in the diet, and the avoidance of recently (within 55 years) burned areas on the winter range (joly, bente et al. 2007), despite the quick and vigorous regrowth of graminoids (jandt et al. 2008), appear to be initial evidence supporting the importance of climate warming and a lichen-rich winter diet for this herd. furthermore, the initial population estimate for the wah in 2007 revealed a 20% decline from the population high of 490 000 in 2003 (dau, pers. comm.). it has been hypothesized that rangifer herds may become smaller, more sedentary and utilize mountainous habitat more, as a result of climate warming and declining lichen communities (heggberget et al. 2002). the work of holleman et al. (1979) also supports the theory that more mobile rangifer utilize greater proportions of lichen in their diets. thus, the potential loss of dense and extensive lichen communities in the arctic could lead to declines in herd sizes, and changes in distribution, behaviour and diet of rangifer, rather than leading towards their extirpation. the role of wildfire in caribou winter ecology has long been debated (leopold & darling 1953; scotter 1970; klein 1982). however, of the four factors affecting lichen abundance, wildfire appears to be the one that land managers have the most control over, and thus garners the most attention. we promote the idea of improving the synthesis of existing research, supporting new research projects to address knowledge gaps and using this information to develop fire management plans for the winter ranges of large, migratory rangifer herds. in addition, an integrated, international effort is needed to investigate the role of lichens in arctic and sub-arctic ecosystems, and the responses of lichens to changes in the environment: changes that have accelerated in recent decades (symon et al. 2005). such an effort should encompass: climate change detection and modelling; the assessment of the long-term impacts of boreal forest and tundra wildfires, and the related soil dynamics; determining the competitive feedbacks between lichens, shrubs and graminoids in plant community structure; and impacts on caribou ecology. furthermore, dramatic changes in seaice dynamics, which strongly influence arctic weather patterns, may lead to even more pronounced changes on terrestrial arctic ecosystems. land managers throughout the arctic could use such data to guide strategies for fire and resource management that fit with the changing climate. acknowledgements we thank all the bureau of land management employees that have worked on the various projects mentioned in this paper, especially r. meyers and j. cole. j. allen, t. chapin, k. kielland, r. meyers, g. theisen, r. van der wal and anonymous reviewers provided comments and discussions that were helpful for developing this manuscript. references ahti t. 1959. studies on the caribou lichen stands of newfoundland. annales botanici societatis zoologicae botanicae fennicae vanamo 30. helsinki: societas zoologica botanica fennica vanamo. arseneault d., villeneuve n., boismenu c., leblanc y. & deshaye j. 1997. estimating lichen biomass and caribou grazing on the wintering grounds of northern quebec: an application of fire history and landsat data. journal of applied ecology 34, 65–78. auclair a.n.d. 1983. role of fire in lichen-dominated tundra and forest–tundra. in r.w. wein & d.a. maclean (eds.): loss of lichens in arctic ecosystemsk. joly et al. polar research 28 2009 433–442 © 2009 the authors 439 role of fire in northern circumpolar ecosystems. pp. 235–256. new york: john wiley and sons. bergerud a.t. 1974. decline of caribou in north america following settlement. journal of wildlife management 38, 757–770. brodo i.m., sharnoff s.d. & sharnoff s. 2001. lichens of north america. new haven: yale university press. callaghan t.v., press m.c., lee j.a., robinson d.l. & anderson c.w. 1999. spatial and temporal variability in the response of arctic terrestrial ecosystems to environmental change. polar research 18, 191–197. cebrian m.r., kielland k. & finstad g. 2008. forage quality and reindeer productivity: multiplier effects amplified by climate change. arctic, antarctic and alpine research 40, 48–54. chapin f.s. iii, shaver g.r., giblin a.e., nadelhoffer k.j. & laundre j.a. 1995. responses of arctic tundra to experimental and observed changes in climate. ecology 76, 694–711. chapin f.s. iii, sturm m., serreze m.c., mcfadden j.p., key j.r., lloyd a.h., mcguire a.d., rupp t.s., lynch a.h., schimel j.p., beringer j., chapman w.l., epstein h.e., euskirchen e.s., hinzman l.d., jia g., ping c.-l., tape k.d., thompson c.d.c., walker d.a. & welker j.m. 2005. role of land-surface changes in arctic summer warming. science 310, 657–660. collins w.b. & smith t.s. 1991. effects of wind-hardened snow on foraging by reindeer (rangifer tarandus). arctic 44, 217–222. cooper e.j., smith f.m. & wookey p.a. 2001. increased rainfall ameliorates the negative effect of trampling on the growth of high arctic forage lichens. symbiosis 31, 153–171. cornelissen j.h.c., callaghan t.v., alatalo j.m., michelsen a., graglia e., hartley a.e., hik d.s., hobbie s.e., press m.c., robinson c.h., henry g.h.r., shaver g.r., phoenix g.k., jones d.g., jonasson s., chapin f.s., molau u., neill c., lee j.a., melillo j.m., sveinbjornsson b. & aerts r. 2001. global change and arctic ecosystems: is lichen decline a function of increases in vascular plant biomass? journal of ecology 89, 984–994. dau j. 2000. managing reindeer and wildlife on alaska’s seward peninsula. polar research 19, 57–62. dau j. 2005a. western arctic herd. in c. brown (ed.): caribou management report of survey and inventory activities, 1 july 2002–30 june 2004. pp. 177–218. juneau: alaska department of fish and game. dau j. 2005b. two caribou mortality events in northwest alaska: possible causes and management implications. rangifer special issue 16, 37–50. dalerum f., boutin s. & dunford j.s. 2007. wildfire effects on home range size and fidelity of boreal caribou in alberta, canada. canadian journal of zoology 85, 26–32. duffy p.a., walsh j.e., graham j.m., mann d.h. & rupp t.s. 2005. impacts of large-scale atmospheric–ocean variability on alaskan fire season severity. ecological applications 15, 1317–1330. dunford j., mcloughlin p., dalerum f. & boutin s. 2006. lichen abundance in the peatlands of northern alberta: implications for boreal caribou. ecoscience 13, 469–474. epstein h.e., calef m.p., walker m.d. chapin f.s. iii & starfield a.m. 2004. detecting changes in arctic tundra plant communities in response to warming over decadal time scales. global change biology 10, 1325–1334. goetz s.j., bunn a.g., fiske g.j. & houghton r.a. 2005. satellite-observed photosynthetic trends across boreal north america associated with climate and fire disturbance. proceedings of the national academy of science 102, 13521–13525. gough l., shrestha k., johnson d.r. & moon b. 2008. long-term mammalian herbivory and nutrient addition alter lichen community structure in alaskan dry heath tundra. arctic, antarctic and alpine research 40, 65–73. heggberget t.m., gaare e. & ball j.p. 2002. reindeer (rangifer tarandus) and climate change: importance of winter forage. rangifer 22, 13–32. helle t. & aspi j. 1983. effects of winter grazing by reindeer on vegetation. oikos 40, 337–343. henry g.h.r. & gunn a. 1990. recovery of tundra vegetation after overgrazing by caribou in arctic canada. arctic 44, 38–42. higuera p.e., brubaker l.b., anderson p.m., brown t.a., kennedy a.t. & hu f.s. 2008. frequent fires in ancient shrub tundra: implications of paleorecords for arctic environmental change. plos one 3(3), e0001744. doi: 10.1371/journal.pone.0001744. hinzman l.d., bettez n.d., bolton w.r., chapin f.s. iii, dyurgerov m.b., fastie c.l., griffith b., hollister r.d., hope a., huntington h.p., jensen a.m., jia g.j., jorgenson t., kane d.l., klein d.r., kofinas g., lynch a.h., lloyd a.h., mcguire a.d., nelson f.e., oechel w.c., osterkamp t.e., racine c.h., romanovsky v.e., stone r.s., stow d.a., sturm m., tweedie c.e., vourlitis g.l., walker m.d., walker d.a., webber p.j., welker j.m., winker k.s. & yoshikawa k. 2005. evidence and implications of recent climate change in northern alaska and other arctic regions. climate change 72, 251–298. holleman d.f. & luick j.r. 1977. lichen species preference by reindeer. canadian journal of zoology 55, 1368–1369. holleman d.f., luick j.r. & white r.g. 1979. lichen intake estimates for reindeer and caribou during winter. journal of wildlife management 43, 192–201. hollister r.d., webber p.j. & tweedie c.e. 2005. the response of alaskan arctic tundra to experimental warming: differences between shortand long-term responses. global change biology 11, 525–536. holt e.a., mccune b. & neitlich p. 2006. defining a successional metric for lichen communities in the arctic tundra. arctic, antarctic, and alpine research 38, 373–377. holt e.a., mccune b. & neitlich p. 2008. grazing and fire impacts on macrolichen communities of the seward peninsula, alaska, u.s.a. the bryologist 111, 68–83. jacobsen e. & skjenneberg s. 1975. some results from feeding experiments with reindeer. in l.r. luick et al. loss of lichens in arctic ecosystems k. joly et al. polar research 28 2009 433–442 © 2009 the authors440 (eds.): proceedings of the first international reindeer and caribou symposium. biological papers of the university of alaska special report 1. pp. 95–107. fairbanks, ak: university of alaska. jandt r.r., joly k., meyers c.r. & racine c. 2008. slow recovery of lichen on burned caribou winter range in alaska tundra: potential influences of climate warming and other disturbances. arctic, antarctic and alpine research 40, 89–95. joly k., bente p. & dau j. 2007. response of overwintering caribou to burned habitat in northwest alaska. arctic 60, 401–410. joly k., cole m.j. & jandt r.r. 2007. diets of overwintering caribou, rangifer tarandus, track decadal changes in arctic tundra vegetation. canadian field-naturalist 121, 379–383. joly k., dale b.w., collins w.b. & adams l.g. 2003. winter habitat use by female caribou in relation to wildland fires in interior alaska. canadian journal of zoology 81, 1192–1201. joly k., jandt r.r., meyers c.r. & cole m.j. 2007. changes in vegetative cover on western arctic herd winter range from 1981–2005: potential effects of grazing and climate change. rangifer special issue 17, 199–207. jorgensen j.c. & buchholtz c.a. 2003. eighteen years of vegetation monitoring in the arctic national wildlife refuge, alaska. accessed on the internet at www.arcus. org/search/meetings/2003/webcast.php on 19 feburary 2009. kasischke e.s. & turetsky m.r. 2006. recent changes in the fire regime across the north american boreal region—spatial and temporal patterns of burning across canada and alaska. geophysical research letters 33, l09703, doi: 10.1029/2006gl025677. klein d.r. 1968. the introduction, increase, and crash of reindeer on st. matthew island. journal of wildlife management 32, 350–367. klein d.r. 1982. fire, lichens, and caribou. journal of range management 35, 390–395. klein d.r. 1987. vegetation recovery patterns following overgrazing by reindeer on st. matthew island. journal of range management 40, 336–338. klein d.r. & shulski m. 2009. lichen recovery following heavy grazing by reindeer delayed by climate warming. ambio 38, 11–16. klein d.r. & vlasova t.j. 1991. lichens, a unique forage resource threatened by air pollution. rangifer 12, 21–27. leopold a.s. & darling f.f. 1953. wildlife in alaska: an ecological reconnaissance. new york: ronald press. mccoy v.m. & burn c.r. 2005. potential alteration by climate change of the forest-fire regime in the boreal forest of central yukon territory. arctic 58, 276–285. messier f., huot j., le henaff d. & luttich s. 1988. demography of the george river caribou herd: evidence of population regulation by forage exploitation and range expansion. arctic 41, 279–287. molau u. & alatalo j.m. 1998. responses of subarctic–alpine plant communities to simulated environmental change: biodiversity of bryophytes, lichens, and vascular plants. ambio 27, 322–329. morneau c. & payette s. 1989. postfire lichen–spruce woodland recovery at the limit of boreal forest in northern quebec. canadian journal botany 67, 2770–2782. moser t.j., nash t.h. iii & thomson j.w. 1979. lichens of anaktuvuk pass, alaska, with emphasis on the impact of caribou grazing. the bryologist 82, 393–408. parry m.l., canziani o.f., palutikof j.p., van der linden p.j. & hanson c.e. (eds.). 2007. climate change 2007: impacts, adaptation and vulnerability. contribution of working group ii to the fourth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. payette s., morneau c., sirois l. & desponts m. 1989. recent fire history of the northern quebec biomes. ecology 70, 656–673. pegau r.e. 1968. growth rates of important reindeer forage lichens on the seward peninsula, alaska. arctic 21, 255–259. pegau r.e. 1969. effect of reindeer trampling and grazing on lichens. journal of range management 23, 95–97. post e. & forchhammer m.c. 2008. climate change reduces reproductive success of an arctic herbivore through trophic mismatch. philosophical transactions of the royal society b 363, 2369–2375. post e. & klein d.r. 1999. caribou calf production and seasonal range quality during a population decline. journal of wildlife management 63, 335–345. racine c.h., patterson w.a. iii & dennis j.g. 1985. tundra fire regimes in the noatak river watershed, alaska: 1956–1983. arctic 38, 194–200. racine c.h., jandt r., meyers c. & dennis j. 2004. tundra fire and vegetation change along a hillslope on the seward peninsula, alaska, u.s.a. arctic, antarctic, and alpine research 36, 1–10. racine c.h., johnson l.a. & viereck l.a. 1987. patterns of vegetation recovery after tundra fires in northwestern alaska, u.s.a. arctic and alpine research 19, 461–469. robinson c.h., wookey p.a., lee j.a., callaghan t.v. & press m.c. 1998. plant community responses to simulated environmental change at a high polar semi-desert. ecology 79, 856–866. rouse w.r., douglas m.s.v., hecky r.e., hershey a.e., kling g.w., lesack l., marsh p., mcdonald m., nicholson b.j., roulet n.t. & smol j.p. 1997. effects of climate change on the freshwaters of arctic and subarctic north america. hydrological processes 11, 873–902. rupp t.s., chapin f.s. iii & starfield a.m. 2000. response of the subarctic vegetation to transient climatic change on the seward peninsula in north-west alaska. global change biology 6, 541–555. rupp t.s., olson m., adams l.g., dale b.w., joly k., henkelman j., collins w.b. & starfield a.m. 2006. simulating the influences of various fire regimes on caribou winter habitat. ecological applications 16, 1730–1743. loss of lichens in arctic ecosystemsk. joly et al. polar research 28 2009 433–442 © 2009 the authors 441 http://www.arcus saperstein l.b. 1996. winter forage selection by barren-ground caribou: effects of fire and snow. rangifer special issue 9, 237–238. scotter g.w. 1967. the winter diet of barren-ground caribou in northern canada. canadian field-naturalist 81, 33–39. scotter g.w. 1970. wildfires in relation to the habitat of barren-ground caribou in the taiga of northern canada. annual proceedings tall timbers conference 10, 85–106. shaver g.r. & jonasson s. 1999. response of arctic ecosystems to climate change: results of long-term field experiments in sweden and alaska. polar research 18, 245–252. shulski m. & wendler g. 2007. the climate of alaska. fairbanks: university of alaska press. soja a.j., tchebakova n.m., french n.h.f., flannigan m.d., shugart h.h., stocks b.j., sukhinin a.i., parfenova e.i., chapin f.s. iii & stackhouse p.w. 2007. climate-induced boreal forest change: predictions versus current observations. global and planetary change 56, 274–296. stern r.o., arobio e.l., naylor l.l. & thomas w.c. 1980. eskimo, reindeer and land. bulletin 59. fairbanks: university of alaska fairbanks. sturm m., racine c. & tape k. 2001. increasing shrub abundance in the arctic. nature 411, 546–547. sturm m., schimel j., michaelson g., welker j.m., oberbauer s.f., liston g.e., fahnestock j. & romanovsky v.e. 2005. winter biological processes could help convert arctic tundra to shrubland. bioscience 55, 17–26. swanson j.d., schuman m. & scorup p.c. 1985. range survey of the seward peninsula reindeer ranges, alaska. anchorage ak: usda soil conservation service. symon c., arris l. & heal b. (eds.) 2005. arctic climate impact assessment. cambridge: cambridge university press. syroechkovskii e.e. 1995. wild reindeer. washington, d.c.: smithsonian institution libraries. tape k., sturm m. & racine c. 2006. the evidence for shrub expansion in northern alaska and the pan-arctic. global change biology 12, 686–702. thing h. 1984. feeding ecology of the west greenland caribou (rangifer tarandus groenlandicus) in the sisimuit–kangerlussuaaq region. danish review of game biology 12. copenhagen: vildtbiologisk station. thomas d.c., barry s.j. & alaie g. 1996. fire–caribou–winter range relationships in northern canada. rangifer 16, 57–67. thomas d.c. & edmonds j. 1983. rumen contents and habitat selection of peary caribou in winter, canadian arctic archipelago. arctic and alpine research 15, 97–105. thomas d.c. & hervieux d.p. 1986. the late winter diets of barren-ground caribou in north–central canada. rangifer special issue 1, 305–310. thomas d.c. & kiliaan h.p.l. 1998. fire–caribou relationships: (iv) recovery of habitat after fire on winter range of the beverly herd. technical report series 312. edmonton: ab: prairie and northern region, canadian wildlife service. thomas d.c., kiliaan h.p.l. & trottier t.w.p. 1998. fire–caribou relationships: (iii) movement patterns of the beverly herd in relation to burns and snow. canadian wildlife service, prairie & northern region technical report series 311. edmonton: ab: prairie and northern region, canadian wildlife service. tyler n.j.c. 1987. body composition and energy balance of pregnant and non-pregnant svalbard reindeer during winter. symposia of the zoological society of london 57, 203–229. van der wal r. 2006. do herbivores cause habitat degradation or vegetation state transition? evidence from the tundra. oikos 114, 177–186. van der wal r., brooker r., cooper e. & langvatn r. 2001. differential effects of reindeer on high arctic lichens. journal of vegetation science 12, 705–710. van wijk m.t., clemmensen k.e., shaver g.r., williams m., callaghan t.v., chapin f.s. iii, cornelissen j.h.c., gough l., hobbie s.e., jonasson s., lee j.a., michelsen a., richardson s.j. & rueth h. 2003. long-term ecosystem level experiments at toolik lake, alaska, and at abisko, northern sweden: generalizations and differences in ecosystem and plant type responses to global change. global change biology 10, 105–123. walker m.d., wahren c.h., hollister r.d., henry g.h.r., ahlquist l.e., alatalo j.m., bret-harte m.s., calef m.p., callaghan t.v., carroll a.b., epstein h.e., jonsdottir i.s., klein j.a., magnusson b., molau u., oberbauer s.f., rewa s.p., robinson c.h., shaver g.r., suding k.n., thompson c.c., tolvanen a., totland ø., turner p.l., tweedie c.e., webber p.j. & wookey p.a. 2006. plant community responses to experimental warming across the tundra biome. proceedings of the national academy of science 103, 1342–1346. wiedermann m.m., nordin a., gunnarsson u., nilsson m.b. & ericson l. 2007. global change shifts vegetation and plant–parasite interactions in a boreal mire. ecology 88, 454–464. wein r.w. 1976. frequency and characteristics of arctic tundra fires. arctic 29, 213–22. white r.g., bunnell f.l., gaare e., skogland t. & hubert b. 1981. ungulates on arctic ranges. in l.c. bliss et al. (eds.): tundra ecosystems: a comparative analysis. pp. 397–483. cambridge: cambridge university press. wookey p.a. 2007. climate change and biodiversity in the arctic—nordic perspectives. polar research 26, 96–103. loss of lichens in arctic ecosystems k. joly et al. polar research 28 2009 433–442 © 2009 the authors442 census of seabird colonies on nordaustlandet , svalbard, and in neighbouring localities in 1978 and 1979 palle uhd jepsen and a r e m o b e k jepsen, p. u . & mobak, a . 1983: census of seabird colonies on nordaustlandet. svalhard. and in neighhouring localities in 1978 and 1979. polar research 1 n . s . . 199-209. seabird colonies were censused during the summer expedition of norsk polarinstitutt to nordaustlandet. svalbard, in 1978 and 1979, and to kongs~ya in 1979. an outline is givcn of thc distribution of the ,pecir, together with an estimate of the number of breeding pairs in the colonies. twenty-five colonies were ccnsused; seven were visited both years. four colonies with more than 1,000 breeding pairs of the most abundant species, brunnich‘s guillemot and kittiwake, were found on nordaustlandet. palle u h d jepsen, vildtreseruarkontoret, 8410 rmnde, d e n m a r k : a r e mobcek, fylkesmannen i h e d m u r k . h e d m a r k fylkeshus. 2300 hamur. norway; october i981 (reciised june iyx.3). introduction the seabird colonies in spitsbergen, particularly those in the western fjords and o n prins karls forland, have been investigated and described by lovenskiold (1964), larsen (1965), and norder haug (1967,1974). norderhaug et al. (1977) men tion that seabird colonies of more than 1,000 breeding pairs are unlikely on nordaustlandet. they also state that colonies of between 1,000 and 10,000 birds have been registered by lovenskiold (1964) among others on the islands and coasts of hinlopen. a single colony on alkefjellet had more than 100,000 birds. o n kong karls land. between 1.000 and 10,000 seabirds have been registered in two colonies. not until lately, in connection with the summer expeditions of norsk polarinstitutt (np), have quantitative and qualitative data been collected from the sea bird colonies on nordaustlandet, the surrounding islands, and on kong karls land. two biologists joined the n p summer expe ditions in 1978 and 1979 to census breeding species in seabird colonies in northeastern svalbard. t h e results of these registrations are presented in this report. t h e breeding conditions of the following sea birds a r e described: fulmar fulrnarus glacialis, kittiwake rissa tridactyla, little auk alle alle, briinnich’s guillemot uria lomuia, puffin fra tercula arctica, and black guillemot cepphus grylle. t h e breeding occurrence of glaucous gulls larus hyperboreus and ivory gulls pagophiln eburnea is also described. leaders of the ornithological programme were a r e m o b a k in 1978 and palle uhd jepsen in 1979, with assistants per magne jensen and hdkon robak, respectively. the authors a r e grateful for their efforts and cooperation through out the programme. thanks are also d u e to par ticipants on other projects for a number of obser vations which form part of the material for this report. material and methods the study area t h e investigated seabird colonies are found on localitjes possible t o visit within the limits which had to b e expected, as the foremost aim of the expedition was within topographic and geologic investigations. the different routes taken by the expedition vessel m / s ‘norvarg’ in 1978 and 1979. and weather conditions made it impossible t o census all the same colonies in 1979 as in 1978. but a large area was covered and seabird colonies not visited before were registered both years. the study areas in 1978 and 1979 are shown in fig. 1. observations in 1978 were made mainly in the northwestern part of nordaustlandet, along the 200 palle u h d jepsen & a r e mobmk 1 g e r e n , lomfjorden. 28 july kapp f a n s h a h e and alkeflellet, 29 july selanderneset. 31 j u l y martensoya and nelsonoya. 4 august hamiltonbukta, 8 august depotodden and goosbukta, 9 august waldenoya. 11 august karl xi1 byane. 12 august f o y n ~ y a and brochoya, 27 august t h e 1979 rsgistrations included some of the localities visited in 1978 (tables 1 and 2 ) , but in and localities in the northeastern part of nord austlandet t h e following localities for seabird i &-7 addition included k o n g s ~ y a in kong karls land, .uu ..rcs 1t.d \ \ \ i l < \ h l l 1 1 i fig 1 map of sur\c\ drea in 1978 and 1979 the large inland localitiea for 1979 \\ere sur\ebed mainl, from a helicopter 0 “ i”. 1 were reg,stered mosselbukta, 26 july martensaya. parryoya, phippsoya, nordkapp, west side of hinlopen. the following seabird coldepotodden, august and august onies were registered: nordkapp. 23 july vesle tavleaya. 916 ju1) and w a l d e n ~ y a , 8 august foynoya and b r o c h ~ y a . 18 august tuble i . shematic outline of localities registered l from the shore. g from rubber dinghy, e from the expedition vessel, h from helicopter. ‘i’ shows that time (number of hours) has not been the iimiiing factor for accomplishing the counts, and ‘ d indicates that aiailahle time was not sufficient for complete registrations. 1978 l y i 9 time spent localities l g e time spent l g e h (hours) h’orda u s t l a s d e t vesle tavleeya y y t nelsonoya x y t nordkapp y x t x 2 1 martenseya y y t x i t parryoya x 11 t p h i p p s ~ y a x i t u’aldenclya x x d y z t t depotodden x i x 3 t goosbukta x t selanderneset x d zeipelfjellet x x t karl xi1 o > a n e x i x 3 1 foynoya y t x x 4 t brochoya y t x y x 2 t kapp bruun x x . i t damhdugen x d winsnesbreen x d ko.vgsoya kapp kiihurg y t sjogrentiellst \ t z o r d n c x t x t r c t r i u \ t iellct \ t spi tsr e r g f \ xorth oi rundiscn \ d gersn y d kapp fanshaac \ d ilosselhukta y 2 1 t ab le 2 . l ar ge st n um be r of b re ed in g pa ir s in s ea bi rd c ol on ie s on n or da us tl an de t. k on g k ar ls l an d (k on gs 0y a) . an d n w s pi ts be rg en , re gi st er ed i n 19 78 a nd 1 97 9. t he n um be rs pr ec ed in g pl ac e na m es a re p lo tt ed i n th ei r co rr es po nd in g ge og ra ph ic al p os it io n in f ig . 2. + : br ee di ng . bu t no t co un te d bi rd s. d at e l oc al iti es 19 78 n o r d a u s t l a n d e t 1. n or dk ap p 24 .7 2. v es le t av le ~ y a 26 .7 3. m ar te ns q ya 4. 8 4. n el so nq ya 4. 8 5. p ar ry ~ y a 6. p h ip p s~ y a 8. d ep ot od de n 9. 8 9. g oo sb uk ta 9 .8 10 . s el an de rn es et 31 .7 1 1 . z ei pe lf je ll et 13 . f o y n ~ y a 27 .8 14 . b ro ch oy a 27 .8 is . k ap p b ru un 16 . d am ha ug en 17 . w in sn es br ee n k o n g s q y a 18 . k ap p k ob ur g 19 . s jo gr en fj el le t 20 . n or dn es et 21 . r et zi us fj el le t 22 . n or th o f r un di se n s p it s b e r g e n 23 . g cr cn 28 .7 24 . k ap p f an sh aw e 29 .7 25 . m os se lb uk ta 7. w al de no ya 11 .8 12 . k ar l x i1 0 y an e 12 .8 b ru nn ic h' s b la ck fu lm ar k it ti w ak e gu il lc m ot pu ff in gu il le m ot iv or y gu ll (f ul m ar us (r u su l it tl e au k ( u ri u (f ra rr rc ir la (c ep ph rr s (p ag op hi la gl nc r a lis ) tr rd ac h la ) ( m e d ie ) lo rn u 1 0 ) ar cr ic a) gr yl le ) eb ur tt eo ) 19 79 19 78 19 79 19 78 19 79 19 78 19 79 19 78 19 79 19 78 19 79 19 78 19 79 19 79 6. 8 6. 8 75 0 54 0 6. 8 6. 8 6. 8 2. 8 14 0 20 0 50 62 0 10 .8 15 0 19 .8 30 17 .8 18 .8 25 21 .8 21 .8 50 9. 8 60 15 00 10 00 26 .7 20 30 0 > 50 12 00 10 0 so 45 0 15 0 50 > 70 25 0 16 80 25 0 42 0 46 0 12 0 + 60 80 10 40 > 50 12 0 16 00 30 0 50 50 8 50 > 10 60 75 50 70 75 > 36 10 0 > 60 20 60 5 15 + 12 15 + 10 + 65 11 0 85 14 0 10 26 10 15 15 25 10 00 35 202 pulle u h d jepsen & a r e m o b e k karl xi1 (ilyane. 19 august kapp bruun. 21 august s . repaya. 32 august from 13 to 25 august. h . robak surveyed bird cliffs on kongssya. several rather small bird cliffs were found in 1979 in connection with aerial surveys of eider sonlaterin rnollissinzn and rein deer rungifer m r a n d l i s plat\.rhj~nchus. ice arid observution conditions quantitative registrations of seabird colonies in nordaustlandet are hampered by the extreme weather conditions prevailing in the arctic regions. some colonies could not be counted because of bad weather in 1978 and 1979. in other cases poor visibility and precipitation must be blamed for the inferior quality of a few counts. the count at waldensya was difficult in 1978. and in 1979 bad weather prevented a visit to nelsonsya. in 1978. registrations of breeding pairs in sev eral colonies could be made from a rubber dinghy below the cliffs. but this method could only be used to a limited extent in 1979. when solid bum mer ice surrounded the islands and coastline i n the northwestern part of nordaustlandet (table 1). we therefore had to rely on helicopter trans port to most localities. such conditions may t o a high degree influence the biological qualit! of the registrations. and make a comparison of the two years‘ results questionable. in addition. the time difference of the two years’ summer regis trations at each locality also complicates the pos sibilities for comparative studies. census methods binoculars (7 x 50 or 8 x 40) and telescopes (2sx) were used for seabird registrations. tele scopes could only be used from the deck of the expedition vessel in stable weather. and for regis trations on land. when registrations were made from the rubber dinghy below the bird cliffs or on land just below the cliffs. binoculars were most useful. both groups tried to make as exact counts as possible. but because of the large size of some colonies in relation to the registering time avail able. it was sometimes necessary to make counts in representative parts of the colonies o n l y . and on the basis of these counts to estimate the total number of breeding pairs. each of the groups made several independent registrations both years, and these were later compared in order to find the most representative total. if the deviation between the results was too great. registrations were made jointly, the observ ers drawing each other‘s attention to groups of birds or areas that might have been overlooked in the first count. for documentation of the size of the bird col onies and the distribution of the cliffs, a sketching-in o n polaroid photos was made in 1978. this method was only used t o a limited extent in 1979. when. on the other hand, drawings were used. in both years some colonies were photographed in black/white for later registration. a t a possible later selection of a representative number of col onies on nordaustlandet for more systematic investigations, this method would supply valuable documentation material, especially for species such as kittiwake and briinnich’s guillemot. i n the field the prime objective was to locate as many seabird colonies as possible and estimate the approximate number of breeding pairs. t h e method of sketching-in colonies, either on polaroid photos or o n drawn sketches, will make it possible to evaluate the fluctuation pattern of some species, as the space occupied in a given cliff area will change if the populations increase or decrease in number. t h e method appears to give a significant and reliable index, giving future observers a good basis for continuous studies and enabling them to estimate where it is important to concentrate investigations. the sketching-in method might be used with reasonable certainty in size estimates of colonies of h l m a r s , kittiwakes, and brunnich’s guillemots, but it cannot really b e used for registering little auks. puffins, or black guillemots. breeding more scattered on the cliffs. in 1979 the observers could use the two expe dition helicopters, and a total of 26 hours were spent o n various biological surveys. this meant that great areas could be surveyed for breeding colonies. real registrations are not possible and justifiable from aircraft. however, since flying i n the immediate vicinity of colonies causes an unacceptable degree of disturbance. on later occasions it was possible to investigate some of the registered colonies on land. helicopter was also used to register breeding and moulting eiders. results census of seabird colonies 203 sketches of seabird colonies on nordallstlandet the positions of the various seabird species on the cliffs are shown in figs. 3-10. only localities where it has been possible to sketch in the extent of the colonies are shown. the size of the colonies has been sketched-in on three cliffs both i n 1978 and 1979. for future registrations of the cliffs visited in 1978 and 1979, it is possible with advantage to draw up sketches of some other areas, e.g. parryoya, phippsoya, and waldenoya. there the colonies are found concentrated in well-defined cliff areas. in other areas, however, the birds breed very sparsely, for instance at foynoya, brochoya, and in two localities on kongsoya. in these cases sketches would hardly be of much help. in figs. 12 and 16 for respectively fulmars and black guillemots, some colonies appear with an arrow. these colonies were registered from helicopter in 1979, but no real count was made. seabird colonies four different colonies with more than 1,000 breeding pairs were found on nordaustlandet during the np expeditions in 1978 and 1979, on selanderneset and n e l s o n ~ y a in 1978 and on martensoya and kapp brunn in 1979 (fig. 2). in three of the colonies, more than 1,000 pairs of one species were breeding. on nelson0ya, 1,700-1,800 pairs of brunnich’s guillernot were found and on martensoya and kapp bruun there were approximately 1,200 and 1,000 kittiwake pairs, respectively. one colony of 500-1 .ooo pairs of seabirds was found on martensoya in 1978, and two on parryoya and waldenoya in 1979. in 1978 a colony with possibly more than 100,000 pairs was registered west of hinlopen on the well-known alkefjellet mountain. no real count of breeding pairs was made. two colonies at geren in lomfjorden and kapp fanshawe on the lornfjordhalv~lya peninsula were also found to have 1,00&1,500 pairs of kittiwake and 2,000 pairs of kittiwake/brunnich’s guillemot, respectively. a colony of 1,500 pairs of kittiwake and several smaller colonies on sjogrenfjellet on kongscbya, kong karls land, were found in 1979. breeding pairs in seabird colonies registered in 1978 and 1979 are listed in table 2. the numerals preceding locality names refer to geo graphical position (see fig. 2). fig. 2 . seabird colonies recorded and counted in 1978 and 1979. the colonies are shown in three size categories, and include the species mentioned in table 2. numbers refer to the list of localities in table 2 . fig. 3. northwest side of vesle tavleeya with seabird colonies sketched in. legend (refers to figs. >5 and 7-10): ---: col onies counted in 1978, -: colonies counted in 1979.1. fulmar fulmarus glacialis, 2 . kittiwake risssa friductyla, 3. little auk aile ane, 4. briinnich’s guillemot uria lomuia, 5. black guil lemot cepphus grylle, 6 . mixed colonies of nos. 2 and 4 , 7. mixed colonies of nos. 3 and 5. vesle taule@ya (fig. 3) is an island in the s j u ~ y a n e group and, together with rossoya, is svalbard’s northernmost island at almost 81”n. briinnich’s guillemot is dominant among the breeding birds, and the colony is found at the northwestern corner of the island, opposite r o s s ~ y a . on the west side of the island a few little auks and black guillemots are found breeding, together with the rather small colony of puffins. the colony was counted in 1978. 204 palle uhd jepsen & are mobcek -. - fig. 4. martensdya observ.ed from the southeast with seabird colonies sketched i n . for legend. see fig. 3 . martens@yu (fig. 4) is the easternmost island in the sjuciyane group, located a t approximately 80"40'n. the seabird colonies a r e found on the south-southeast side of s d v b e r g e t , where the kittiwake is represented in the largest numbers. little auks. black guillemots, and puffins breed sparsely. t h e colonies were counted both in 1978 and 1979. n e l s o n @ p ~ (fig. 5) is o n e of the smallest islands in the sjuciyane group lying 200-300 metres south west of parryejya. t h e island has two rather large seabird colonies containing the largest registered concentrations of breeding briinnich's guillemots on nordaustlandet. in addition, a rather large colony of kittiwakes and a rather small population of black guillemots and puffins are found. t h e colonies are found o n the north and northwest sides (fig. 5b) and o n the south side of the island. o n the sketch (fig. 5a) showing the south side of the island. the briinnich's guillemots area is indicated rather inaccurately, because the birds appear extremely concentrated o n clear. vcrtical geological layers in the cliff. o n the west side of k . _-r ,--\ fig. 5 . nelsondya observed from the south (a), and the north (b). with seabird colonies sketched in. on the southern cliff briinnich's guillemots were found scattered over the dashed line. but concentrated around vertical crevices (shaded areas). for legend, see fig. 3 . the island t h e birds were breeding very sparsely, making it difficult t o sketch-in t h e colonies accu rately. they have therefore been left out. t h e colonies were counted in 1978. depotodden (figs. 6 and 7) is situated in the western part of laponiahalvoya (approximately 80"zo'n). t h e seabird colonies a r e found o n the steep cliffs facing south. t h e only colony of ful mars registered on nordaustlandet in 1978 was found here, and it also showed t h e highest number of breeding pairs among the few colonies regis tered in 1979. both years the colony was found on the cliff north of the cottage. in 1979 a rather small colony of kittiwakes was found on the cliff together with breeding little auks. a small num ber of black guillemots were observed breeding both in 1978 a n 1979, little auks and black guil lemots were found scattered o n the cliff, and their breeding areas are therefore difficult t o sketch-in on the map. h g 6 depotodden. 2 august 1979. compare with sketch in fig. 7 photo: palle uhd jepsen fig. 7. depotodden with seabird colonies sketched in. fulmars were breeding scattered i n the colonies. for legend, see fig. 3. see also fig. 6. selanderneset (fig. 8) is the name of the north western corner of scaniahalv0ya at the mouth of wahlenbergfjorden (approximately 79"35'n). the seabird colonies are found southwest of the foreland opposite hinlopen. colonies of briinnich's guillemots and kittiwakes were found in 1978 totalling more than 1,000 pairs. a few black guillemots were also registered. t h e local ities were not visited in 1979. karl xi1 oyane (fig. 9) a r e two islands north of eastern nordaustlandet at approximately 80"35'n. they a r e connected by a high beach ridge consisting of stone and very coarse-grained gravel. t h e southern cliff of the northern island has a very lush moss vegetation on the lower eroded slope. a colony of kittiwakes was regis tered there both in 1978 and 1979 totalling 30 and 120 pairs, respectively. both the southern and northern islands have populations of black guil lemots. t h e little auk breeds o n the northern island and at least two pairs were registered in 1979. selanderneset 1978 fig. 9. karl xi1 (dyane seen from the southeast with seabird colonies sketched in. for legend, see flg. 3. kapp bruun (fig. 10) is the northernmost cliff massif o n a peninsula in the northeastern part of nordaustlandet, east of prins oscars land. the seabird colonies a r e found on a steep cliff at approximately 80"16'n. in 1979 more than 1,000 pairs of kittiwakes were found breeding in four small colonies, and a well-defined colony of about 60 pairs of black guillemots. in addition, approx imately 80 pairs of black guillemots were breeding scattered o n the cliff. the little auk was breeding in small numbers. the seabirds the following is a description of the breeding occurrence of seabirds in the areas investigated in 1978 and 1979. the survey is hardly satisfac tory, however, as there are probably still some unknown colonies. in 1979 large areas in the northern and western parts of nordaustlandet (fig. 1) were surveyed by helicopter in connection with other registrations, without discovery of any big seabird colonies (see table 1). kapp b r u u n 1979 fig. 8. southwest side of selanderneset with seabird colonies sketched in. for legend, see fig. 3. fig. zo. north side of kapp bruun with seabird colonies sketched in. for legend. see fig. 3. 206 palle uhd jepsen & are mobmk found in the seabird colonies o n kong karls land and spitsbergen, marked in fig. 2. i ll1"l'irli. ylrcldll. 1 i n l fig. 11. colonies of fulmars shown as the greatest number of breeding pairs counted in 1978 and 1979. the colony marked with arrows was surveyed from helicopter in 1979 and is not included in table 2 . fulniar fulmarus glacialis (fig. 11). the great est colony on nordaustlandet was registered on depotodden, where the number of breeding pairs was estimated at 140 in 1978 and approximately 200 in 1979. on zeipelfjellet in palanderbukta. 100-150 pairs of fulmars were counted in 1979 (0. lauritzen pers. comm.). the most remarkable discoveries of breeding fulmar colonies were at damhaugen and wins nesbreen in 1979, with respectively 50 and 60 pairs. the colonies were situated respectively 15 and 12 km from the nearest coast, and were regis tered from helicopter. discovery of breeding fulmars at inland local ities. e . g . on nunataks, is also mentioned by nor derhaug et al. (1977). no breeding fulmars were - kittiwake rissa tridactyla (fig. 12). the northern-most seabird colony in svalbard was registered on martensoya, with the highest num ber of breeding pairs on nordaustlandet in 1979, viz. 1,200. i n 1978 the breeding population here totalled 700-750 pairs. breeding kittiwakes registered on nelsonoya in 1978 numbered 480-540 and were distributed in three colonies. the largest colony, with 35c 400 pairs, was discovered on the south side of the island. this locality was not visited in 1979. in addition small colonies were found in goosbukta and on depotodden. a colony of more than 600 pairs was found on selanderneset in 1978. the kapp bruun colony is the second largest discovered on nordaustlandet in 1979 with 1,040 breeding pairs. the colony was counted on 21 august, at which time most of the juvenile birds were close to fledging. some had already left the cliff, as juvenile birds could be watched from the vessel. a colony of 120 pairs on karl xi1 byane visited on 19 august had fledged juvenile birds in the colony. it was also visited in 1978, when about 30 pairs were registered. the total number of breeding pairs registered on nordaustlandet in 1978 was just under 2,000, and in 1979, 2.400 pairs. i n 1979 more than 2,000 pairs were counted on kong karls land (kongsoya). distributed in five colonies, the larg est having 1,600 pairs. little auk alle alle (fig. 13). breeding little auks were found i n greater or smaller numbers fig. 12. colonies of kittiwakes shown as the greatest number of hreeding pairs rccorded in 1978 and 1979. fig. 13. colonies of little auks shown as the greatest number of breeding pairs in 1978 and 1979. census of seabird colonies 207 nordaustla n det svalbard o w i r n fig. 14. colonies of briinnich‘s guillemots shown as the greatest number of breeding pairs in 1978 and 1979. in practically all investigated seabird cliffs. in addition, the species bred alone in small numbers at many localities; this was noticed during the helicopter survey in 1979. it is often difficult to estimate the exact number of breeding little auks in colonies. the birds breed scattered, and the nests are often found at the tops of cliffs in the most inaccessible places. the number of breeding pairs in the various colonies are therefore given with certain reservations, and should be regarded as absolute minimum numbers. in 1978, the largest colony of breeding little auks was registered on nordkapp, 250-300 pairs. fifty pairs were counted in the same place in 1979, but this small figure is probably due to the fact that there was very little time available for counting that year. the real number must cer tainly be much higher, judging from the great number of little auks seen flying near the colony. one flight, for instance, had approximately 200 individuals. in 1979 the largest colony of little auks was found on parryaya, with about 450 breeding pairs. no breeding little auks were dis covered during the surveys of kongsaya. briinnich’s guillemot uria lomvia (figs. 14 and 15). only a few, but big colonies were found on nordaustlandet. the highest number of breed ing pairs was registered on sjudyane in 1978, where nelsonaya alone counted three different colonies totalling 1,680 pairs. in addition, 250 pairs were counted in a colony on vesle tavlecbya. these two islands were not visited in 1979, when a colony of 100 pairs was found on depotodden. approximately 250 pairs were breeding on fig. 15. colony of briinnich’s guillemots on walden~ya, 6 august 1979. photo: palle uhd jepsen. waldenaya in 1978, and more than 400 pairs in 1979. in 1978 a colony of 600 pairs of briinnich’s guillemots was found on selanderneset in wal denbergfjorden. this area was not visited in 1979. on spitsbergen a mixed colony of kittiwakes and briinnich’s guillemots was found in 1978. a total of 2,000 pairs were found on kapp fan shawe. as previously mentioned, the large colony on alkefjellet (lavenskiold 1964) was registered too, probably also including a considerable popu lation of briinnich’s guillemots. no briinnich’s guillemots were recorded on k o n g s ~ y a in 1979. a total of 2,640 and over 500 breeding pairs were registered on nordaustlandet in 1978 and 1979, respectively. the figures cannot be directly compared, however, because parts of sjuayane were not visited in 1979. the choice of nesting site in relation to the geological structure of the cliff is significant for the briinnich’s guillemot. this was particularly clearly observed at selanderneset in 1978, where the nests were always placed on shelves of hori zontal, sedimentary rocks (fig. 8). puffin fratercula arctica. this bird breeds very sparsely at nordaustlandet. the largest total number of pairs was found on waldencbya in 1979, 208 palie u h d jepsen & are m o b a k fig. 16. colonies of black guillemots shown as the greatest number of breeding pairs counted in 1978 and 1979. colonies marked with arrows were surveyed from helicopter in 1979 and are not included in table 2. where the breeding population was estimated at minimum 36 pairs. in addition, the species was found scattered in small quantities on other islands, among others on vesle tavleoya. the species was not observed on kongsoya in 1979. black gicillernot cepphus grylle (fig. 16). this bird only breeds in small colonies o n nordaust lander and on kongsoya. most often together with other species. t h e black guillemot does not always breed in well-defined colonies. but the nests are sometimes seen scattered o n the cliffs. several small colonies of black guillemots, with no other species breeding in the immediate vicin ity, were observed during aerial surveys along the coasts around prins oscars land, glenhalvoya. fig. 17. little auks on karl xi1 oyane. 19 august 1979. photo palle uhd jepsen. and repoyane in 1979. because of t h e very lim ited occurrence of breeding black guillemots, the count figures from the two years must be taken as absolute minima. a t nordaustlandet a little less than 300 pairs were recorded in 1978, a n d 1,100 pairs in 1979. t h e great difference is first and foremost d u e t o higher aerial survey results in 1979. on kongsoya approximately 40 pairs of black guillemots were recorded in 1979. glacuoils gull larus hyperboreus. this bird breeds scattered o n nordaustlandet, and also occurs o n k o n g s ~ y a . it is found mainly in the immediate vicinity of other seabird colonies. t h e largest number of pairs recorded within a well defined area was six pairs in 1979; a total of 40 pairs were counted in connection with seabird colony surveys. ivory gull pagophila eburnea. this bird was not observed breeding o n nordaustlandet in 1978 and 1979, but o n kongsoya five rather small colonies totalling more than fifty pairs were recorded in 1979. eight pulli were caught and ringed. accord ing to lovenskiold (1964) ivory gulls breed on s t o r ~ y a and kvitoya, but the species was not recorded at these localities in 1978 and 1979. ahlmann & malmberg (1931) also mention that t h e ivory gull is a common breeding bird on kvitoya. t h e species is quite widespread in areas with drifting ice around nordaustlandet, and in 1978 and 1979 more than t e n individuals were observed several times a day when the expedition vessel passed through ice covered waters. discussion this report is o n e of several contributions describ ing t h e bird-life in these arctic regions and, to a limited extent, comparing the population sizes by observing t h e same colonies in two successive years. it has been mentioned that the figures for some species, first of all for the little auk, black guillemot, and puffin, must be regarded as abso lute minima. as it is difficult t o produce exact figures for birds breeding scattered and in impass able mountain regions. undiscovered seabird col onies probably exist along the coast of norden skioldbukta, rijpfjorden, and duvefjorden. i n addition, some seabird colonies have probably been overlooked in wahlenbergfjorden. census of seabird colonies 209 the rather different recording methods used in 1978 and 1979, mainly because of the greater extention of solid ice in 1979 compared with the year before, may complicate a direct comparison of the numbers of breeding pairs in colonies vis ited and recorded both years. when counting from a boat below a cliff, the size of the breeding population will often be underestimated. this is especially so in the case of breeding briinnich’s guillemots and fulmars, where some birds are hidden behind others or are sitting so far in on the shelves. that they escape notice. counts made from the mountain top on the other hand will be impeded by a poorer general view and will also cause some disturbances in the colonies. but. if plenty of time is available, the method will probably give good information of the number of breeding pairs present. the two methods may profitably be combined, if circum stances permit. norderhaug (1974) points to the possibility of recording nonbreeding individuals as breeding pairs in the seabird colonies. this risk must absolutely be taken into consideration. counts after the middle of august, when birds start to leave the colonies (norderhaug et al. 1977), can also give a wrong impression of popu lation size. the largest seabird colonies in svalbard are found in the western part of the archipelago, where the favourable influence of the gulf stream on the climate and biological production forms the basis of the. for arctic regions, extremely high density in the breeding seabird populations. farther east, around nordaustlandet, the sum mer sea temperature decreases to under 0°c compared to 2 5 3 ° c west of spitsbergen (l0venskiold 1964). this must to a high degree influence the ecological conditions for the birds, and be one of the reasons for the relatively lower number of breeding pairs here. great annual variations in the distribution of solid ice around nordaustlandet must also influence breeding suc cess and thus cause great, annual fluctuations in the number of breeding pairs in the colonies. to get more information on these questions, it is important that the counts started be supple mented with breeding biology studies, including production analyses, mortality studies, and inves tigations of the food supply available. the development of new methods for estimat ing breeding populations more exactly should be encouraged. with this end in view, small seabird cliffs with less than 1,000 pairs can be chosen, which may be counted with reasonably great accuracy. counts should be made several times during 24-hour periods over a fairly lengthy period of time to ascertain day and night varia tions caused by the activity pattern of the birds, the weather, temperature, etc. (norderhzug 1980). the accuracy of counts is reduced the larger the size and the higher the density of colonies; selected colonies must therefore be frequently photographed in order to provide reference material and documentation. references ahlmann. h. w. & malmberg, s . 1931: s o f n f n a r l i d polliaoer. stockholm. 301 pp. larsen. t. 1965: ornitologiske unders~kelser fra den nord vestre del av vestspitsbergen sornmeren 1967. norsk polar inst. a r b o k 1963. 25p263. l~venskiold, h. l. 1964: avifauna svalbardensis. n o r s k polar insr. skrifter n o . 1 2 9 , 460 pp. norderhaug, m . 1967: trekkforhold, stredstrohet og pardan nelse hos alkekonge p l svalbard. fauna 20(4). 236244. norderhaug, m . 1974: studier av sj0fuglkoloniene p i fugle huken, prins karls forland nasjonalpark. n o r s k polarmst. a r b o k 1972. 9f106. norderhaug, m . , brun. g . & mollen, g . u. 1977: barentshav ets sj0fuglressurser. n o r s k polarinst. m e d d . n o . 104, 119 pp. norderhaug, m . 1980: breeding biology of the little auk (plautus a l l e ) in svalbard. norsk p d a r i n s r . skrtfrer no. 173. 45 pp. meetings25(2).indd 189polar research 25(2) upcoming meetings north atlantic climate and ecosystems: a current threat? 11–12 september 2006 reykjavik, iceland www.hafro.is/symposium session on alpine and arctic biodiversity and ecology, 36th annual conference of the ecological society of germany, switzerland, and austria 11–15 september 2006 bremen, germany www.gfoe-bremen-2006.de/ 2006 alaska park science symposium 12–14 september 2006 denali national park and preserve, alaska, usa www.nps.gov/akso/symposium international glaciological society british branch annual meeting 13–14 september 2006 keele, uk www.esci.keele.ac.uk/igs2006 36th annual northwest glaciology meeting 15–16 september 2006 fairbanks, alaska, usa www.northwestglaciology.org session on interface processes between the ocean, atmosphere, sea ice, and snow in polar re gions, joint igac/cacgp/wmo symposium 17–23 september 2006 cape town, south africa www.atmosphericinterfaces2006.co.za/ international ice drilling technology workshop 17–23 september 2006 sheperdstown, west virginia, usa www.idt-workshop.unh.edu workshop on the uses of photography to detect change in the cryosphere 18–22 september 2006 juneau, alaska www.earthslot.org/photoworkshop/ workshop for polar earth observing network for the international polar year 4–6 october 2006 dresden, germany www.geo.tu-dresden.de/ipg/polenet alpine snow workshop 5–6 october 2006 munich, germany www.alpinesnowworkshop.org/ continues next page erratum the article by m. uchida et al. in polar research 25(1), “estimation of the annual primary production of the lichen cetrariella delisei in a glacier foreland in the high arctic, ny-ålesund, svalbard” (pp. 39–49), included a misplaced reference to smith & gremmen (2001) in the last paragraph of page 47. the correct citation is to: cooper, e. j., smith, f. m. & wookey, p. a. 2001: increased rainfall ameliorates the negative effect of trampling on the growth of high arctic forage lichens. symbiosis 31, 153–171. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <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> /nld <feff004700650062007200750069006b002000640065007a006500200069006e007300740065006c006c0069006e00670065006e0020006f006d0020005000440046002d0064006f00630075006d0065006e00740065006e0020007400650020006d0061006b0065006e0020006d00650074002000650065006e00200068006f00670065002000610066006200650065006c00640069006e00670073007200650073006f006c007500740069006500200076006f006f0072002000610066006400720075006b006b0065006e0020006d0065007400200068006f006700650020006b00770061006c0069007400650069007400200069006e002000650065006e002000700072006500700072006500730073002d006f006d0067006500760069006e0067002e0020004400650020005000440046002d0064006f00630075006d0065006e00740065006e0020006b0075006e006e0065006e00200077006f007200640065006e002000670065006f00700065006e00640020006d006500740020004100630072006f00620061007400200065006e002000520065006100640065007200200035002e003000200065006e00200068006f006700650072002e002000420069006a002000640065007a006500200069006e007300740065006c006c0069006e00670020006d006f006500740065006e00200066006f006e007400730020007a0069006a006e00200069006e006700650073006c006f00740065006e002e> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice a diagnostic study of the arctic ocean winter density driven circulation in 1973-79 igor v . polyakov and nikolay y u . doronin polyakov. i. v. & doronin, n. y u . 1999: a diagnostic study of the arctic ocean winter density-driven circulation in 1973-79. polar resrordi ir(1). 27-38. diagnostic computations of density-driven circulation for seven winters from 1973 through 1979 were carried out. the only forcing was provided by observed temperature and salinity data collected during on site russian winter surveys in 1973-79. computed circulations from 1973 through 1978 were close to the mean circulation obtained earlier by averaging observed 1973-79 temperature and salinity (polyakov & timokhov 1994). the computed i979 density-driven circulation flowed counter-clockwise to the north of the laptev sea. this circulation pattern was caused by an anomalous salinity distribution associated with changes in the atmospheric circulation regime in 1979. prevailing offshore winds blew fresh water from the laptev and east siberian shelves toward fram strait. fresh water was exchanged for saltier intermediate water that upwelled to the surface along the slope. the observed surface salinity anomalies at the continental slope of the laptev sea i n 1979 increased by several salinity units. one may speculate that the same process may have caused the observed salinification of the eurasian basin in the 1990s. 1. v . polwkoc. iritertmrional arctic rrseurch center, univrrsity of alaska fairbanks. fuirbanks. a k , 99775-7221. u s a : n . y u . doronin. ecoshelf; p.o. box 850, 199048, s i . petersburg. russiu. introduction the characteristics of surface currents in the arctic ocean are well known owing to a number of observations obtained from drifting buoys (fig. 1 : thorndike & colony 1982), and from manned ice drift camp trajectories (treshnikov 1985). the major features of the circulation are the trans polar drift stream, which flows from the chukchi sea slope toward fram strait, and the anticyclonic beaufort gyre. however, analysing atmospheric pressure charts and drift patterns of manned polar stations, gudkovich (1961) pointed out that summer ice drift and surface water circulation may alternate between anticyclonic and cyclonic. serreze et al. (1989) used drifting buoy data for 1979-85 to demonstrate that in late summer to early autumn the ice motion can indeed become cyclonic. using modelling results and observa tional data. proshutinsky & johnson (1997) have found that i n the central arctic, wind circulation and resulting wind-driven motion in the upper ocean alternate between anticyclonic and cyclonic. shifts between these two regimes occur at 5 t o 7 year intervals, resulting i n a 10 to 15 year period. the anticyclonic circulation regime has been observed for 1946-52, 1958-62, 1972-79, and 1983-88. the cyclonic circulation regime pre vailed during 1953-57, 1963-71, 1980-83, and 1989-96. measurements of the deep ocean circulation are difficult due to year-round ice cover. aagaard (1989) summarized existing observations on deep currents and concluded that general water trans port in the polar basin takes the form of narrow boundary currents along the ocean peripheries. these currents move opposite to surface currents. f i g . 1. surface current5 in the arctic ocean (adapted from thorndike b colony 1982. j . grophys. res. 87 [cri, p. 5850; copyright by the american geophysical union: printed uith permission of the authors and agu). 28 i n the interior of the canadian basin the currents are weak, and their kinetic energy is concentrated in mesoscale eddies. according to aagaard, thermohaline currents are the main component of arctic ocean subsurface circulation, and their intensity is comparable to that of the thermohaline currents in the greenland sea. modelling studies help to compensate for the lack of observational information and to improve understanding of the mechanisms affecting natural processes. hakkinen (1993) used a coupled ice ocean model to examine ice and ocean behaviour for an explanation of the salinity anomaly in the greenland sea during the 1960s. she demonstrated the important role of wind-driven circulation in the arctic in the formation of temperature and salinity anomalies in the north atlantic. zhang et al. (1998) found a strong link between the wind pattern over the central arctic and the atlantic water transport from the greenland and barents seas into the arctic ocean, and pointed out that in the 1990s an increased penetration of the atlantic water from the barents sea caused salinization and warming in the eurasian basin. previously, steele & boyd (1998) had used observational data to reveal a remarkable salinification and warming there. they stressed that the salinity anomaly in the upper ocean layer reached up to several parts per thousand (ppt). according to steele & boyd (1998), this anomalous salinization had not been observed before. in this study we use russian observational data to demonstrate that observed salinization of the upper ocean in the 1990s is not unique, and that analogous event occurred in 1979. using simple diagnostic calculations we show how ocean thermohaline circulation responds to this salinity anomaly. given the forcing. the diagnostic method renders a three-dimensional distribution of current for the steady-state flow. the first diagnostic calculation using an integrated vorticity balance equation for the stream function appeared in 1969 (sarkisyan 1969). holland & hirschman (1972) produced a steady-state solution for the north atlantic circulation using a primitive equation model. sarmiento & bryan ( 1 982) used a robust model with a newtonian damping factor to force the temperature and salinity toward climatological values. this methodology was widely used later; for example. it was applied by hibler & bryan (1987) and zhang et al. (1998) in their coupled sea ice-ocean models for the arctic. i . v. polycikov & n . yu. doronin t a h k 1. number of oceanographic stations for each winter survey i n 1973-79. yelir 1973 1974 1975 1976 1977 1978 1979 numherofatations 172 166 182 152 117 127 118 temperature and salinity data in this study, we used temperature and salinity data for each winter from 1973 through 1979, with measurements covering most of the arctic ocean. the number of oceanographic stations for each year is presented i n table 1. the areas covered by the observations varied. the largest areas were measured in 1974-76. the number of stations in 1973 was approximately the same as in 1974-76. but did not include a region adjacent to the canadian archipelago. temperature and salinity data for the arctic marginal seas in 1977 were not available, and we used data for the central arctic only. observations in 1978 and 1979 also omitted an area adjacent to the canadian archipelago. the positions of the oceanographic stations in 1979 are shown in fig. 2. despite the lower number of oceanographic stations in 1977-79, the data density was approximately the same as in 1974 76 due to some reduction of the total area of observations. aircraft were used for all surveys. the planes landed on the drift ice, holes were drilled, the water temperature was measured, and water samples were taken using nansen bottles. salinity was determined by silver chloride titration. the precision of the temperature and salinity measure ments was to 0.01'c and 0.01 ppt, respectively. the measurements were carried out at russian standard oceanographic depths of 5 , 10, 15,20.25, 30, 40, 50, 75, 100, 150, 200, 250. 300, 400, 500, 600, 750 and 1000 m, and at 500 m intervals from 1000 m to the bottom. the data were examined to correct obvious errors: missing values in the vertical profiles were estimated by linear inter polation from neighbouring points; and spline interpolation was used to calculate the temperature and salinity values at every grid point. model and design of numerical experiments a three-dimensional primitive equation z-coordi nate free surface ocean model was used in this a dilignostic stu& cf the arctic owari winter density-driver1 circulation iri 1973-79 2 9 study. as a part of a coupled ice-ocean model. i t has been applied, for example. to simulate currents and sea level elevations in the arctic ocean (polyakov et al. 1998). the model incorporates a turbulent closure model, which follows from the equation for turbulent kinetic energy and is ;i relation between the eddy viscosity coefficient. vertical shear of the horizontal velocity. and buoyancy. a kinematic boundary condition for the vertical velocity at the surface allows repro duction of fast external surface gravity waves. including tides. the model incorporates splitting of the original three-dimensional momentum equation$ for the depth-averaged equations and for the vertically varying equations (blurnberg & mellor 1983; song & haidvogel 1994). the horizontal viscosity coefficient is constant and equal to 5 . 10‘ cin’/s. the finite-difference ap proximation used in the model is described in polyakov ( 1996). the numerical model domain incorporates uniform horizontal resolution with ail increment of a x = 55.56 km (fig. 3). the diagnostic computation technique devel oped by sarkisyan (1991) was used in these experiments. given the density forcing, this f i g . 2. posiriow of station5 duting russian oceanographic u r v e y in 1979. diagnostic method renders a three-dimensional distribution of current for the steady-state flow. in this particular experiment, the only forcing was the density distribution for seven years starting with 1973 and ending with 1979. we applied the primitive equation ocean model, but the heat and salt balance equations were omitted because the density was assumed to be constant across time. at the open boundaries. zero sea level and zero velocity derivatives normal to the open boundary were specified. the position of the open boundary in every experiment was determined by available information on temperature and salinity. the locations of the oceanographic stations and the areas of the ocean covered by the observations varied from year to year. sarkisyan ( 1991) showed that the effect of boundaries in diagnostic experi ments may be traced in the grid points nearest to the boundaries only. our results demonstrate the accuracy of this conclusion because there is no numerical noise i n the computed velocities and sea level elevations at the open boundaries. therefore, we did not apply any special method, such as the flow relaxation scheme (engedahl i995), to determine the velocity at the open boundary. 30 i . v. polvakov & n . yu. dot-onin f i g 3. the arctic ocean bathymetry. 1 = chukchi sea, 2 = east siberian sea, 3 = laptev sea, 4 = kam sea. 5 = barents sea, 6 = greenland sea. 7 = beaufobrt sea. 8 = canadian archipelago, 9 = spitsbergen. 10 = nansen basin, 1 1 = lomonosov ridge. there were seven diagnostic computations for each winter from 1973 through 1979. the time dependent behaviour of volume-averaged mean total energy was used as a criterion of the steady state solution. the time required to obtain a stable solution for each experiment vaned from 22 to 30 days. the ocean model was not coupled with an ice model i n this study. the results of diagnostic computations of the density-driven circulation omitting the effects of wind seem relatively unaffected by the stresses between the drifting ice and the surface ocean currents. moreover, sarkisyan (1991) has argued that the oceanic density structure is adjusted to the wind forcing; therefore, the effect of winds is partly incorporated into the density field. results the density-driven component of the arctic ocean circulation, computed by mean winter temperature and salinity for 1973-79, has been discussed i n polyakov & timokhov (1994) and is presented i n fig. 4. the major features of the surface circula tion are the trans polar drift stream and the anticyclonic beaufort gyre, with its corresponding positive sea level elevations of up to 30 cm in the a diagriostic stu& of the arctic ocean winter density-driven circulation in 1973-79 3 1 fi,q. -1. computed mean winter density-driven circulation i n the arctic ocean. dashed line delineates the area shown i n figs. 5-7. ( a ) sen level elevotion (cm) and wrface currents. vectors are plotted at every other grid point. (b) near-bottom currents. vectors are plotted at every grid point. vectors with value less than 0.25 cnds are not shown. the acale of vectors: arrow length of 0.5 d corresponds to current velocity 0.25 < v < 0.5 c d s ; ito ow length of 1 d corresponds to 0.5 < v < 2.5 c d s : arrow length of 1 .s d corresponds to 2.5 i v < 5.0 c m k :mow length of2 d corresponds to 5.0 < v < 10.0 cnds; and m o w length of 2.5 d corresponds to v > 10.0cnds. v is velocity magnitude. d i s grid cell length. ared without observations has no vectors. centre of the rotation. in the computed surface density-driven circulation. an anticyclonic gyre is generated by the salinity minimum at 2 5 0 m and deeper, located north and north-west of greenland with relatively weak (up to 2-3 cnds) currents: the corresponding sea level maximum is about 13 cm there. on the east siberian sea shelf, the westward coastal current obtained i n our experiments contradicts the commonly accepted circulation pattern on this shelf (gorshkov 1980). nikiforov & shpaikher ( i 980) depicted an eastward current there, but we do not know whether their circulation pattern was obtained by observations or by modelling. note also that our computation omits the effect of winds, which is the major contributor to shallow water circulation. a complex balance of various forces that maintain the observed circula tion on the arctic shelves may be responsible for these different directions in the coastal currents. the computed currents maintain their direction with depth on the siberian shelf and at the continental slope of the chukchi and east siberian seas. at the slope of the laptev sea the surface and near-bottom currents move in opposite directions. more typically, surface and bottom currents in the arctic ocean are directed at some angle to each 32 i. v . polvukov & n . yii. doroniri f i g . 4. continued. other, and the greater the velocity. the smaller the angle. this result contradicts aagaard’s sugges tion (1989) that surface and deep circulations have opposite directions in the arctic ocean. again, our computation does not take winds into account; wind-induced surface circulation may differ sub stantially from the density-driven circulation. the sea level elevation and surface currents computed with the use of the winter density distributions for 1973, 1978 and 1979 are depicted i n figs. 5a, 6a and 7a. figs. 5b, 6b and 7 b show the corresponding near-bottom circulation. the com puted density driven circulation during these years was in one way or another anomalous. the plots for 1974-77 are not presented because the computed circulation for these years was close to the mean circulation depicted in fig. 4. the variation in the location of the centre of anticyclonic rotation i n the beaufort sea, deter mined by the local sea level maximum, is relatively small from 1973 to 1978. the part of the trans polar drift stream contiguous with the continental slope of the arctic seas is stable, and is determined by the bottom topography. away from the continental slope, the location of the trans polar drift stream becomes unstable from year to year with deviations up to 250-300 km. the thermohaline circulations on the shelves of the chukchi, laptev and east siberian seas have small temporal variations. both the location and intensity of the anticyclonic gyre to the north and north-west of greenland are variable in time. as a result, the sea level maximum in the averaged pattern is submerged and currents are weak (fig. a diiignostic stuclv of the arctic ocean winter density-driven circulation in 1973-79 33 f i g . 5 . computed winter density-driven circulation in the arctic ocean i n 1973. ( a ) sea level elevation (cm) and surface currentb. vectors ore plotted at every other grid point. (b) near bottom curreiits. vectors are plotted at every grid point. vectors w i t h value leys than 0.15 c d s are not shown. scale of vectorb is shown i n fig. .i. 34 i . v. polyakov & n . yu. dot-onin f i g . 6 . computed winter density-driven circulation in the arctic ocean in 1978. (a) sea level elevation (cm) and surface currents. vectors are plotted at every other grid point. (b) nedr hottom currents. vectors are plotted at every grid point. vectors with value less than 0.25 cm/s are not shown. scale of vectors is shown in fig. 4. a diugnostic study of the arctic ocean winter density-driven circulation in 1973-79 35 t d ~ k 2. the averaged kinetic energy of the winter thermoha line currents for 1973-79 (kj). discussion year 1973 1974 197.5 1976 1977 1978 1979 energy 0.28 0.11 0.09 0.05 0.08 0.41 0.21 4 4 . the intensity of the thermohaline circulation in 1973-78 was very different. dynamic processes were especially pronounced in 1978 (fig. 6). when the sea level elevation in the beaufort sea was greater than 50 cm, with a corresponding increase in the current velocity. table 2 shows the averaged-over-the-domain kinetic energy of the density-driven currents. this characteristic con firms that density-driven circulation was particu larly strong in 1978. at the same time, atmospheric processes during the winter of 1978 were very stable, with the extreme development of the arctic high (petrov 1983), which apparently resulted in increased water and ice circulation. the general water mass transport in deep layers is concentrated in relatively narrow currents along the continental slopes and ridges. in the abyssal areas the currents are weak and form topographic eddies. this conclusion does not seem to follow from plots presented; however. this apparent disapree ment resides in the problem of plotting the vectors. normalized vector plots, with vector length plotted as a percentage of the maximum vector length, would have shown only 3-4 narrow flows along the continental slope of siberia, the beaufort sea, spitsbergen, and along lomonosov ridge. the other vectors would have been reduced to points. such plots would show the general mass transport and would agree well with aagaard‘s conclusion ( 1 989) that the maximum currents are at the arctic ocean margins. however, since this method would provide little information on the basin as a whole. we scaled the vectors, and each range is shown as a vector of a certain length. for example, an arrow length of 2.5 d (d is the length of the grid cell side) corresponds with all vectors with modules higher than 10 c d s . the computed density-driven circulation of 1979 is atypical (fig. 7). the trans polar drift stream, and circulation in the nansen basin and on the shelf of the chukchi and east siberian seas are the opposite of average conditions (fig. 4). but because the oceanographic survey in 1979 was carried out over a limited area of the arctic ocean it is not possible to draw a conclusion about the circulation in the arctic ocean as a whole. diagnostic computations are a popular and inexpensive method of estimating circulation with the use of observational data and a mathematical model. however, such computations have at least two serious shortcomings: the first is the sensi tivity of the solution to “noise” caused by non stationary processes affecting the temperature and salinity fields, the second shortcoming is that the model topography disagrees with the observed temperature and salinity used in the computations. an adjustment method that has been suggested to reduce these weaknesses of the diagnostic ap proach (sarkisyan & demin 1983; demin et al. 199 1) consists of using diagnostic calculations that keep temperature and salinity constant i n time, followed by a short-term prognostic computation. this method has been applied by ezer & mellor ( 1 994) to simulate north atlantic circulation. these authors note that their model yields dynamically adjusted velocities and sea level heights. we did not use any special method for the diagnostic computations because the level of numerical noise in the computed velocities and sea level elevations was relatively low. the computed trans polar drift stream, the anticyclonic beaufort gyre, and currents over the shelf of the arctic seas are the consistent elements of the arctic thermohaline circulation from 1973 through 1978. a sea level elevation maximum with corresponding anticyclonic rotation to the north and north-west of greenland is also persistent i n the computed current patterns for 1973-78. however. large variability in this circulation resulted in a weak overall average. the general water mass transport in deep layers is concentrated in relatively narrow currents along the continental slopes and ridges. in the abyssal areas the currents are weak and form topographic eddies. the computed density-driven circulation in 1979 was atypical when the direction of the major circulation branches was opposite to the mean pattern. the reason for this unusual situation lies with the anomalous salinity distribution in 1979. that was a transitional year between the anticy clonic (the 1970s) and cyclonic (the 1980s) circulation regimes (proshutinsky & johnson 1997). which implies that very different wind conditions existed in 1973-78 compared with 1979. a possible explanation of the anomalous salinity distribution in the eurasian basin in 1979 36 i . v. polyakov & n . yu. doroniri fig. 7. computed winter density-driven circulation i n the arctic ocean in 1979. (a) sea level elevation (cm) and surface currents. vectors are plotted at every other grid point. (b) near bottom currents. vectors are plotted at every grid point. vectors with value less than 0.25 c m / s are not shown. scale of vectors is shown in fig. 4. a cliagnostic study of the arctic o c ~ ~ t n winter density-driven circulation in 1973-79 37 f i g . 8. winter surface salinity (ppt) averaged over the period 1973-79. contour interval is 0.5 ppt. may be found in nikiforov & shpaikher (1980). they indicated that salinification and freshening of the upper ocean layer i n this region of the arctic is closely related to the atmospheric circulation, and suggested a scenario in which years with reduced atmospheric surface pressure had prevail ing offshore winds that blew fresh surface water formed by siberian river discharge and ice melt into the northern laptev sea. this surface water is replaced by the saltier underlying water of the nansen basin. the positive salinity anomalies to the north of the laptev sea, which were indicated by russian observations, increased by up to several ppt. nikiforov & shpaikher’s (1980) scenario is confirmed by observational data from the russian oceanographic surveys made in 1973-79. during 1973 through 1978, the surface salinity distribu tion was close to the mean, with a gradual decrease in salinity from the siberian coast toward green land and a salinity minimum in the beaufort sea (fig. 8 ) . in 1979, the surface salinity was at a minimum in the central portion of the nansen basin, a situation apparently caused by freshwater advected by prevailing winds from the siberian shelf (fig. 9). this freshwater was replaced by salty intermediate water that upwelled along the laptev and east siberian slope to the surface. the centre of the maximum, with salinity greater than 34 ppt, was near sevemaya zemlya. thus, russian observations (nikiforov & shpai kher 1980; this study) have shown very strong salinification events in the nansen basin in the i 1 1 fig. y. winter 1979 surface salinity (ppt). contour interval is 0.5 ppt. 38 i . v. polyakov & n . yu. doronin past, which attest to the conclusion that the salinification in the 1990s (steele & boyd 1998) was not unique. the most probable reason for this phenomenon is anomalous winds, as suggested by nikiforov & shpaikher (1980) and steele & boyd (1998), and not increased warm and salty atlantic water coming i n via the barents sea as suggested by zhang et al. (1998). our diagnostic computa tions demonstrate that ocean circulation, as well as salinity, is influenced by such anomalous atmo spheric conditions. acknowledgements. we thank the anonymous referees for many useful comments. references aagaard, k.1989: a synthesis of the arctic circulation. rapports et proces-verbaux des reunions /conseil permanent international pour l’exploration de la mer. 188, 11-22, blumberg. a. f. & mellor, g. l. 1983: diagnostic and prognostic numerical circulation studies of the south atlantic bight. j . geophys. res. 88, 45794592. demin, yu. l., friedrich, r. a,, ibraiev, a. s., sarkisyan, a. s. & sundermann, j. 1991: a note on modelling the world ocean climate. ocean modelling 89, 10-1 1. engedahl, h. 1995: use of the flow relaxation scheme in a three dimensional baroclinic ocean model with realistic topogra ezer, t. & mellor, g. l. 1994: diagnostic and prognostic calculations of the north atlantic circulation and sea level using a sigma coordinate ocean model. j . geophys. res. 99(c7), 14159-1417 i . gorshkov, s . g. 1980: atlas okeanov. severnij ledovitij okean. (atlas of ocean; arctic ocean.) 199 pp. moscow: military defense publishing house. gudkovich, z. m. 1961: svjaz’ mezdu drejfom i’da v arkticeskom bassejne i ledovimi uslovijami v sovetskih arkticeskih morjah. (relationship between ice drift i n the arctic basin and ice conditions in the soviet arctic seas.) trudi okeanologiceskogo komiteta (transactions, oceano graphic committee) 11, 145-148. moscow: academy of science, ussr. hakkinen, s. 1993: an arctic source for the great salinity anomaly: a simulation of the arctic ice-ocean system for 1955-1975. j . geophys. res. 98(c9), 16397-16410. hibler, w. d. 111 & bryan, k. 1987: a diagnostic ice-ocenn model. j . phvs. oceanogr. 7 , 987-1015. holland, w. d. & hirschman, a. 1972: a numerical calculation of the circulation in the north atlantic ocean. j . phys. oceanogr. 2 , 3 3 6 3 5 4 . phy. tellus. 47a(3), 365-382. nikiforov, ye. g. & shpaikher, a. 0. 1980 zakonomernosti formirocanija krupnomusstabnih kolebanij gidrologiceskogo rezima sevemogo ledovotogo okeana. (features of the formation of hydrological regime large-scale variations in the arctic ocean.) 272 pp. leningrad: hydrometeoizdat. petrov, l. s. 1983: struktura atmosferi nad arkticeskim okeanom. (atmospheric stmcture over the arctic ocean.) trudi arkticeskogo i antarkticeskogo naucno-lssledova tel’skogo institutu. (transactions, arctic and antarctic research insfitute.) 125 pp. leningrad: hydrometeoizdat. polyakov, i. v. 1996: diagnostic calculations of the currents and sea level variations of the arctic ocean. izvesriya atmos. and ocean. physics 32, 637-649. polyakov, i. v. & timokhov. l. a. 1994: mean fields of temperature and salinity of the arctic ocean. russian meteorol. hydrol. 7 , 33-38. polyakov, 1. v., kulakov, i. yu., kolesov, s. a,, dmitriev, n. eu., pritchard, r. s., driver, d. & naumov, a. k. 1998: coupled sea ice ocean model of the arctic ocean. j . offshore mech. arctic eng. 120, 77-84. proshutinsky, a. yu. &johnson, m. a. 1997: two circulation regimes of the wind driven arctic ocean. j . geophys. res. 102, 12493-12514. sarkisyan, a. s. 1969: on the shortcomings of barotropic models of the oceanic circulation. izvestiya atmos. and ocean. physics 5 , 8 18-836. sarkisyan, a. s . 1991: modelirovanije dinarniki okeana. (modelling of ocean d.ynamics.) 295 pp. st. petersburg: hydrometeoizdat. sarkisyan, a. s. & demin, yu. l. 1983: a semidiagnostic method of sea currents calculation. large-scale oceano graphic experiments in the wcrp. world climate research programme publication series 2(1), 201-214. sarmiento, j. l. & bryan, k. 1982: an ocean transport model for the north atlantic. j . geophys. res. 8 7 , 394408. serreze. m. c., barry, r. g. & mclaren, a. s. 1989: seasonal variations i n sea ice motion and effects on sea ice concentration in the canada basin. j . geophys. res. 94. 10955-10970. song, y. & haidvogel, d. 1994: a semi-implicit ocean circulation model using a generalized topography-following coordinate system. j . comput. phys. 115, 228-244. steele, m. & boyd, t. 1998: retreat of the cold halocline layer i n the arctic ocean. j . geophys. res. 103, 10419-10435. thorndike, a. s. & colony, r. 1982: sea ice motion in response to geostrophic winds. j . geophys. res. 87, 5845-5852. treshnikov, a. f. 1985: atlas arktiki. (atlas of the arctic.) 204 pp. moscow: main administration of geodesy and carto zhang, j., rothrock, d. a. & steele. m. 1998: warming of the arctic ocean by a strengthened atlantic inflow: model results. geophjs. res. lett. 25(10), 1745-1748. graphy. climate states and variability of arctic ice and water dynamics during 1946-1997 andrey y. proshutinsky, igor v. polyakov & mark a. johnson recently observed changes in the arctic have highlighted the need for a better understanding of arctic dynamics. this research addresses that need and is also motivated by the recent finding of two regimes of arctic ice ocean wind-driven circulation. in this paper, we demonstrate that during 1946-1997 the arctic environmental parameters have oscillated with a period of 10-15 years. our results reveal significant differences among atmosphere, ice, and ocean processes during the anticyclonic and cyclonic regimes in the arctic ocean and its marginal seas. the oscillating behaviour of the arctic ocean we call the arctic ocean oscillation (aoo). based on existing data and results of numerical experiments, we conclude that during the anticyclonic circulation regime the prevailing processes lead to increases in atmospheric pressure. in ice concentration and ice thickness, river runoff, and surface water salinity as well as to decreases in air temperature, wind speed, number of storms. precipitation, permafrost temperatures. coastal sea level, and surface water temperature. during the cyclonic circulation regime the prevailing processes lead to increased air and water temperatures, wind speed, number of storms, open water periods, and to decreases in ice thickness and ice concentration, river runoff, atmospheric pressure, and water salinity. the two-climate regime theory may help answer questions related to observed decadal variability of the arctic ocean and to reconcile the different conclusions among scientists who have analysed arctic data obtained during different climate states. a. y. proshutinsky, i . v. polyakov & m . a. johnson, institute of marine science, universiv o j alaska fairbanks, p.o. bo.r 757200, fairbanks, a k 99775-7220, usa. introduction recently observed changes in the arctic ocean’s hydrographic characteristics (quadfasel 199 1 ; rudels et al. 1994; carmack et al. 1995; carmack & aagaard 1996; morison 1996) and ice condi tions (maslanik, serreze et al. 1996; cavalieri et al. 1997) have highlighted the need for a better understanding of arctic climate variability. for example, morison (1996) reports that the new observational data “indicate a fundamental change in the circulation of the arctic ocean beginning in the early 1990s.” in addition, carmack & aagaard ( 1996) conclude that “remarkable new observa tions call for a revised conceptual model of the arctic ocean, and a rethinking of theory and process parameterization.” our research may help explain these observed changes in the arctic. it builds upon the recent findings of two regimes of arctic ocean ice and water circulation described by proshutinsky & johnson (1997). the two-climate regime theory may help answer questions related to the observed variability of the arctic ocean, and to reconcile the different conclusions among scientists who have analysed hydrographic data, water circulation. ice thickness, ice motion, and other parameters obtained during different climate states. wind-driven circulation regimes proshutinsky & johnson (1997) simulated wind driven ice and water motion in the arctic ocean from 1946 through 1993 and validated the proshutinsky et al. 1999: polar research 18(2), 13.5-142 135 seo level g r a d i e n t s 4 7 2 y o 2 1950 1960 1970 1980 1990 2000 north p o l e slp 1950 1960 1970 1980 1990 2000 ob+yenisei+leno river dischorqe i 1950 1960 1970 1980 1990 2000 barrow permafrost t e m p e r a t u r e 1 .o o 0.5 & 0.0 d -0.5 -1.0 1.5 1950 1960 1970 1980 1990 2000 f i g . 1. decadal variability of (a) sea level gradients in the center of the arctic basin (arctic ocean oscillation). (b) north pole slp anomaly, (c) siberian rivers discharge anomaly, and (d) barrow permafrost temperature anomaly. bars represent annual mean anomaly and solid thick line shows 5 year running mean anomaly. modelled ice motion with data from 630 drifting surface buoys and 31 “north pole” stations. we have updated our model results through 1997. to determine the variability of the arctic ocean’s circulation, the sea level slope near the center of the arctic basin was examined as a measure of cyclonicity and anticyclonicity (see protushinsky & johnson 1997 for details). the time series of the sea level gradients from 1946 through 1997 shows an arctic ocean oscillation (aoo) (fig. la) with two major regimes describing the modelled wind driven ice and water motion. one regime is characterized by anticyclonic circulation (positive anomaly) and the second regime is characterized by cyclonic ice and water motion (negative anomaly). regime shifts between cyclonic and anticyclonic flow occur at 5-7 year intervals, resulting in a 10-15 year period. the anticyclonic circulation regime (accr) is observed i n the model results for 1946-1952, 1958-1962, 1972-79, and 1984-88. the cyclonic circulation regime (ccr) prevailed during 1953-57, 1963-1971. 1980-83, and 1989-1997. in this paper, we compare the simulated and observed sea level at stations along the arctic ocean coastline (fig. 2). coefficients of correlation between observed and simulated sea level are higher than 0.7. the good agreement between modelled and observed parameters confirms a generally accurate reproduction of the ice and water circulation, and further validates the two regime theory. observations the north pole sea level atmospheric pressure (slp), siberian river runoff (ob, yeanisei and lena rivers), barrow permafrost temperature, index of the north atlantic oscillation (nao), dynamical heights i n the beaufort gyre, ice extent in the arctic ocean, sea ice anomalies in davis strait and i n the bering sea, and some other environmental parameters have similar variability to the a 0 0 (fig. 1, table 1). for example. increased bering sea ice extent occurs in the periods of anticyclonic circulation. high atmos pheric pressure at the north pole drives the anticyclonic wind-driven regime and low slp at the north pole leads to the cyclonic circulation. siberian river runoff increases during accr and decreases during ccr. we have examined the recent findings of others on changes observed in the arctic and have attempted to characterize their results i n terms of the two regimes of circulation (table 1). some of these relations can be easily explained while others are difficult to understand. a f u l l comparison is in progress. to compensate for the lack of observa tional data in many of the arctic ocean regions, we have analysed results of a set of numerical experiments using a three-dimensional thermody namic coupled ice-ocean model. thermodynamic aspects of two circulation regimes the experiments with the 3-d thermodynamic 136 climate states and variability of arctic ice and water dynamics dikson (kara sea) 1960 1965 1970 1975 1980 1985 1990 v i z e (karo sea) 1960 1965 1970 1975 1980 1985 1990 uedinenia (kora sea) q -10 1960 1965 1970 1975 1980 1985 1990 zhelanio (kara sea) 8 -208 1960 1965 1970 1975 1980 1985 1990 kotelnyi (loptev sea) 0 -10 8 2 0 1 1960 1965 1970 1975 1980 1985 1990 peschanyi (laptev sea) :2kcl=o’.sl c 2 = 0 . 8 5 ’ c3=0.79 a4 -10 0 ; 5 i -1% 1960 1965 1970 1975 1980 1985 1990 fi,+ 2. annual mean sea level (cm) at the coastal stations and islands of the kara and lnptev seas. solid line depicts observations. dashed line shows simulation result using 1946-1997 slp derived from observations (experiment i). dotted lines ,how simulation result based on 1973-1997 ncar/ncep reanalysis data set (experiment 2 ) . c i , c2. and c 3 are correlntion coefficients between observed and sirnulated sea level in experiment i , experiment 2. and between siniulated seu levels i n experiment i and 2. respectively. location of stations is shown in fig. 6. coupled ice-ocean model were specially designed to further test our hypothesis of two circulation regimes. the model description, experiment de sign. and some preliminary results are presented in proshutinsky et al. (1997a, b) and polyakov et al. (1998). here we discuss results of a simulation of ice and water dynamics for 1987 and 1992, which are typical years of accr and ccr, respectively. analyses of the results of numerical experiments reveal significant differences between environ mental parameters during the two different regimes of arctic system variability. these regimes are not only characterized by differences in the ice drift (fig. 3. table 1 ) and ocean surface currents (not shown), they are also associated with major changes in ice thickness and concentration, water temperature and water salinity of the upper 50 m ocean layer (fig. 4). in general, our 3-d model simulations and observational data show that during accr, the “winter” conditions with cold (see fig. 5 ) and dry atmosphere, increased ice thickness and concen tration, increased water salinity, and decreased water temperature (fig. 4) prevail over the seasonal cycle. during ccr, the “summer” arctic conditions dominate with a relatively warm and wet atmosphere (fig. s ) , decreased ice thickness and concentration, decreased water salinity, and increased water temperature (fig. 4). variability of ice thickness has been discussed by wadhams (1994), mclaren et al. (1994), and vinje et al. (1998). from our theory, this variability is closely related to the two climate regimes (proshutinsky & johnson). for example, during the ccr, the ice in fram strait is thicker than during the accr because thicker ice is transported from the canadian basin. at the same time, ice becomes thinner near the north pole because the transpolar drift is shifted toward greenland and carries relatively thin ice from the siberian seas to the north pole region. an approximately 20% decrease in ice volume occurs in the ccr years. this decrease is defined mainly by changes in the ice thickness. the corresponding decrease of the ice area across the entire arctic ocean is less than 5%. the simulated decrease of ice area during ccr (not shown) is in good agreement with observations (maslanik, serreze et al. 1996; cavalieri et al. 1997). several processes lead to the ice deficit during ccr. counter-clockwise summer ice drift causes a flushing of ice from the siberian sector of the arctic and decreases ice concentration in the central arctic while there is an accumulation and ridging of ice along the coast of the canadian proshutinsky et al. 1999: polar re.worch 18(?), 135-142 137 table i. interpretation of observed and simulated anomalies of environmental parameters in terms of the two regimes theory. n = negative anomaly, p = positive anomaly, a = anticyclonic circulation, c = cyclonic circulation. parameter anomaly accr ccr data source atmospheric vorticity over the polar cap sea level atmospheric pressure nao index before 1968 nao index after 1968 surface air temperature duration of ice melt beason sea ice extent summer ice concentration sea ice thickness ice drift ice extent i n the bering sea ice extent i n davis strait upper 30 m layer circulation upper 50 m layer water temperature i n the upper 50 111 water salinity i n the arctic baain sea level along coast line depth of upper boundary of atlantic water along dynamicdl heights in the beaufort gyre atlantic water temperature atlantic water salinity atlantic water transport through fram strait atlantic water transport through the barents sea deep water formation i n the greenland sea deep water formation in the labrador sea siberian rivers runoff permafrost temperature arctic basin continental slope n p p n n n p p p a p p a n p n p n n n n n p n p n archipelago and northern greenland. the ice transport through fram strait is increased because the ice penetrates to fram strait from the canadian sector of the arctic, and according to observations and our model results, moves faster during ccr. during the following winter, normally ice-free areas of the arctic ocean are covered by first year ice. repetition of this process during several years of ccr leads to a thinning of ice in the central arctic where numerous summer openings result in warming and accumulation of heat in the upper ocean layer which in turn increases the length of the ice melt season. this result agrees with observations (smith 1998). higher water tempera ture of the upper ocean layer during ccr is the second factor reducing the ice volume in the arctic ocean during ccr. atmospheric winds redistri bute ice mechanically and thermodynamic factors lead to changes of ice thickness. according to our model results, 80% of the ice thickness variability p n n p p p n n n c n n c p n p n p p p p p n p n p tanaka et al. 1995 proshutinsky & johnson 1996. 1997; walsh et al. hurrell 1995 hurrell 1995 martin & muroz 1997 smith 1998 maslanik, serreze et al. 1996. cavalieri et al. 1997 maslanik, serreze et al. 1996 proshutinsky et al. 1997a, b. this study proshutinsky & johnson 1997; int. arctic buoy program niebauer 1988 agnew 199 1 proshutinsky et al. 19973, b: jones et al. 1998 ewg 1997 1996 ewg 1997, see references in introduction ewg 1997. introduction ewg 1997. introduction ewg 1997, introduction ewg 1997, introduction ewg 1997, introduction ewg 1997, introduction rudels et al. 1994; this study speculation speculation ewg 1997, introduction osterkamp et al. 1994 between accr and ccr is due to winds and only 20% is due to air surface temperature variability. this conclusion coincides with the results of harder et al. (1997) and maslanik, fowler et al. (1997). additional ice melt freshens the upper ocean layer and increases the outflow of fresh water from the central arctic into the greenland sea through fram strait (not shown). discussion recent observations show that after 1989 many ocean characteristics changed from the 195 1-1980 russian climate study (gorshkov 1983). many researchers have compared atmosphere, ice and ocean parameters before and after 1989 (walsh et al. 1996; mcphee et al. 1998; morison 1996; jones et al. 1998; steele & boyd 1998; zhang et al. 138 climate states and variability of arctic ice and water dynamics 1987 1992 f i g . 3. seasonal variability of the ice drift and ice edge location (solid line) i n 1987 (accr) and 1992 (ccr). vectors are shown at every fourth grid point. dotted areas depict location of fast ice. 1998), and describe this change as a climate shift. we believe that similar changes in the arctic have occurred i n the past. satellite and buoy drift observations of arctic ice demonstrate two modes (defined by gloerson et al. [ 19921 as siberian and alaskan) i n the summer pack ice behavior, which are evenly distributed over the period between 1979 and 1987 (before the climate shift i n 1989). the siberian mode occurs when the beaufort gyre and the transpolar drift are well-developed (corresponds to accr). the alaskan mode occurs when the beaufort gyre weakens and transpolar c . in . . -1.40 n i 0.90 8 0.85 0.80 2 0.70 3.4 ; 3.2 3.0 2 2.8 2 2.6 0 2.4 2 2.2 2.0 . * , , . , 0.75 * , 2 4 6 8 1 0 1 2 m o n t h fig. 4. seasonal variability of ice and water parameters in 1987 (accr, solid line) and i n 1992 (ccr, dotted line). water temperature and salinity are averaged for the upper 50 rn ocean layer of the arctic basin. drift shifts toward greenland (corresponds to ccr). recent results by jones et al. (1998) are in agreement with this conclusion about cyclonic ice and water motion in the arctic after 1989. they deduce circulation patterns from the distribution of atlantic and pacific waters in the upper 30 m layer of the arctic ocean based on nitrate and phosphate analyses, and conclude that the surface layer moves cyclonically (as in ccr). the joint us.-russian atlas of the arctic ocean (ewg 1997) presents temperature and salinity averaged decadally from the 1950s through the 1980s; unfortunately, this decadal averaging does not coincide with the periods of natural variability based on the aoo. because the decadal averaging aliases much of the existing natural variability, it would be better to average the proshutinsky et al. 1999: polar research 18(2), 1.75-142 139 0 " -10 t? -20 v 30 2 m e t r e air temperature 2 4 6 8 10 12 surface wind w e e d 2 4 6 8 10 12 sea ice concentration 1 .oo 0.90 0.70 0.60 0.50 bp 2 4 6 8 1 0 1 2 precipitation e l o ~~ 2 4 6 8 1 0 1 2 arctic rivers runoff 2 4 6 8 1 0 1 2 buoy speed 0 2 4 6 8 1 0 1 2 months f i g . 5. seasonal variability of environmental parameters for multi-year mean accr (thin lines) and ccr (thick lines) conditions. information for the periods of accr and ccr. fortunately. some differences between ccr and fig. 6. salinity difference of the upper 50 m layer between the 1980s and 1970s (data from ewg. 1997). hatched area depicts regions with salinization of the upper 50 m layer in the 1980s. d, v, u , z, k, and p show location of stations dikson, vize. uedinenia, zhelania, kotelnyi and peschanyi (see fig. 2). accr have survived even in the decadally averaged atlas data. if we decadally average sea level gradients (not shown) we can conclude that the 1950s experienced climate conditions close to the mean; that the '60s and '80s were decades dominated by the ccr; and that during the 1970s, the accr prevailed in the arctic. the salinity (fig. 6) and temperature (not shown) anomalies obtained from the atlas show that, indeed, in the 1980s the upper ocean layer was fresher and warmer, and that in the 1970s it was colder and saltier than russian climatological data presented in gorshkov (1983). note that the 1970s and 1980s were not purely anticyclonic and cyclonic; there fore anomalies are not so pronounced as in the 1990s (mcphee et al. 1998; steele & boyd 1998). the nature of these processes is still uncertain. there is a good correlation between river runoff and aoo before 1966, but the later correlation is weaker. there is also good correlation between the nao and ice concentration i n summer in the laptev sea (not shown), between nao and aoo, and between nao and air temperatures in the norwegian sea after 1966 (not shown), between nao and north pole slp after 1978 (not shown); but before 1966, these correlations had different signs or the processes were not correlated at all. a temporal boundary between correlated and un 140 climate states and variability of arctic ice and water dynamics correlated processes in the north atlantic coin cides with the beginning of the great salinity anomaly (1964-68). in the north pacific the temporal boundary coincides with the climate shift that occurred in 1976 (niebauer 1988). both climate shifts have changed the interdependence of natural processes in the arctic-north atlantic and arctic-north pacific systems. the reasons for these shifts should be the subject of future research. acknowledgements. this research has been supported hy the wadati fund of the geophysical institute. uaf, and by a grant from the national science foundation (opp 9806926). we would like to express our gratitude to our reviewers. their suggestions greatly improved this paper. references agnew, t. 1991: simultaneous winter sea ice and atmospheric circulation anomaly patterns. fiph ams conference on c h u t e vuriations (preprints). pp. 362-365. denver: ameri can meteorological soc. carmack, e. c. & aagaard, k. 1996: the dynamic arctic ocean: spatial, temporal, and conceptual heterohene\ies. abstract. eos, truns. am. geophys. union 7 6 ( 3 ) , os 12. carmack, e. c., macdonald, r. w.. perkin. r. g., mclaughlin. f. a. & pearuon, r. j. 1995: evidence for warming of atlantic water i n the southern canadian basin of the arctic ocean: results from the larsen-93 expedition. geophys. rex lett. 22(y). 1061-1064. cavalieri. d. j.. gloersen, p.. parkinson, c. l., comiso. j. c. & zwally, h. j. 1997: observed hemispheric asymmetry in global sea ice changes. science 278. 1104-1 106. ewg (environmental working group) 1997: j o i n t u.s.-kir.\ siun atlus of the arctic oceun. cd-rom. boulder: national snow and ice data center. gloersen, p., campbell. w. j.. cavalieri. d. j.. coiniho. c.. parkinson. c. l. & zwally, h. j. 1992: arctic urid anforcfic s c c i ice. 1978-1 987: satellite / ' u s s i v r m i c r o ~ a i ~ i ~ obser~~rrrioris urid unulysis. washington, d.c.: nasa. gorshkov. s . g. 1983: arctic oceun. vol. 3. in s. g. gorshkov (ed.): the w r l d oceun atlas. oxford: pergamon. harder, m.. hilmer, m., lemke, p.. steiner. n. & windmuller. m. 1907: modeling the variability of sea ice, 1973-1997. proceedings of the conference on polar prot.e.s.sev und glohtrl cliniurr. rosario. orcas island, washington. usa, 3-6 november 1997. pp. 74-75. hurrell, j . w. 1995: decadal trends in the north atlantic oscillation: regional temperatures and precipitation. science 269, 6 7 6 6 7 9 . jones. e. p., anderson. l. g. &swift, j. h. 1998: distribution of atlantic and pacific waters in the upper arctic ocean: implications for circulation. geophys. res. leu. ?5/6), 765-768. martin. s . & muiioz. e. a. 1997: properties of the arctic 2 meter air temperature field for 1979 to the present derived from a new gridded dataset. j . c h i . /o, 1428-14.10. maslanik. j.. fowler, c.. emery, w. & weatherly. j. 1997: on the interanliual variability of arctic sea ice transport: relationships to atmospheric circulation modes and signifi cance for gcm assessments. proceedings of the conference on polur processes and global climure. rosario, orcas island. washington, usa. 3-6 november 1997. pp. 1 5 6 1 5 8 . maslanik, j . a,, serreze, m. c. & bany, r. g. 1996: recent decreases i n summer ice cover, and linkages to anomalies in atmospheric circulation. geophys. res. lett 23(13), 1677-1680. mclaren, a. s . , bourke, r . h., walsh. j. e. & weaver, r. l. 1994: variability of sea-ice thickness over the north pole from 1958 to 1992. i n 0. m. johannessen et al. (eds.): the polur oceans und their role in shuping the global environ ment. pp. 363-371. washington, d.c.: american geophysi cal union. mcphee, m. g.. stanton. t. p., morison, j . h. & maninson, d. g. 1998: freshening of the upper ocean in the arctic: is perennial sea ice disappearing? geophys. res. lett. 25( 10). 1729-1732. morison. j . e. 1996: changes in upper ocean hydrography measured during the 1993 cruise of the uss pargo. abstract. eos, truns. am. geophys. union 76(3), os 12. niebauer, h. j . 1988: effects of el nino-southern oscillation and north pacific weather patterns on interannual variability in the sub-arctic bering sea. j . geophys. res. 93. 5051-5068. osterkamp, t. e.. zhang, t. & romanovsky, v. e. 1994: evidence for a cyclic variation of permafrost temperatures in northern alaska. perniqfrosr perigluciul process. 5. 1 3 7134. polyakov. i . v.. kulakov. 1. y u . , kolesov, s . a,, dmitriev. n. eu., pritchard, r. s . , driver, d. & naumov, a. k. 1998: coupled sea ice-ocean model of the arctic ocean. j . qffshort. mech. arct. eng. 120, 77-84. proshutinsky, a. & johnson, m. 1996: two regimes of arctic ocean circulation from ocean models and observations. abstract. 1996 ocean sciences meeting. san diego. ca. eos, truns. an]. geopliys. union 76(3). os29. proshutinsky. a. & johnson, m. 1997: two circulation regimes of the wind-driven arctic ocean. j . geophys. res. 102, 12493-12514. proshutinsky. a., johnson, m. & polyakov, 1. 1997a: decadal hcale variability of the arctic system. proceedings of conferencr on polur processes und globul clitnute. rosario, orcas island, washington. usa, 3-6 november 1997. pp. 206-208. proshutinsky, a., polyakov, 1. & johnson, m. 1997b: seasonal variability of the arctic ocean processes based on observations and numerical modeling. proceedings of con .ference on polar processes und globul clirnutr. rosario, orcas island, washington, usa, 3-6 november 1997. pp. 203-205. quadfasel. d. 1991: warming in the arctic. nurure 3.50. 385. rudels. b., jones, e. p., anderson, l. g. & kattner, g. 1994: on the intermediate depth waters of the arctic ocean. in 0. m. johannessen et al. (eds.): the polur oceans mid their role in shupin,q the glohul environment. pp. 3 3 4 6 . washington, d.c.: american geophysical union. steele. m. & boyd t. 1998: retreat of the cold halocline layer i n the arctic ocean. j . geupiys. res. 103(c5). 10,419-10,336. smith, d. m. 1998: recent increase in the length of the melt season of perennial arctic sea ice. geophys. res. lett. 25(5). 655-658. tanaka, h. l., kanohgi, r. & yasunari. t. 1995: recent abnormal weather in the arctic. proceedings of the w d a t i proshutinsky et al. 1999: polar research / 8 ( 2 ) , 135-142 141 conference on global change and the polar clirnate. 7-10 november 1995, tsukuba science city, japan. geophysical institute, university of alaska fairbanks. pp. 13-16. vinje, t., nordlund, n. & kvambekk, a. 1998: monitoring ice thickness i n fram strait. j . geophys. rps. 103(c5), 10,43710,449. wadhams, p. 1994: sea ice thickness changes and their relation to climate. in johannessen et al. (eds.): the polar oceans and their role in shaping the global environment. pp. 337-361. washington, d.c.: american geophysical union. walsh, j. e., chapman, w. l. & shy, t. l. 1996: recent decrease of sea level pressure in the central arctic. j . clim. 9, 480-486. zhang, .i., rothrock, d. a. & steele, m. 1998: warming of the arctic by a strengthened atlantic inflow: model results. geophys. res. len. 25(10), 1745-1748. i42 climate states and variability of arctic ice and water dynamics correlations between pelagic distribution of common and brunnich’s guillemots and their prey in the barents sea w e l l einar erikstad, truls moum a n d wim vader erikstad, k. e., moum, t. & vader, w. 1990: correlations between pelagic distribution of common and briinnich’s guillemots and their prey in the barents sea. polar research 8 , 77-87. correlations between guillemots (including common guillcmots uria aalge and briinnich’s guillemots u . lomuia) and their prey (divided into five prey categories, capelin mallatus villosus, herring ciupea harengus, polar cod boreogadus saida, plankton, and a mixture of other prey species) at two depths (10-100m and 100-200 rn) were estimated along an extended transect of 3,060 nautical miles (5,667 km) in the barents sea in april/may 1986. spatial concordance was highest during daylight hours when the largest number of birds were seen on water (presumably feeding birds). capelin was the single prey category which was most often associated with birds but no single prey category could alone explain the distribution of birds. although only a small fraction of guillemots could be identified to species, there was some evidence that capelin were of greater importance lo common than t o briinnich’s guillemots. overall correlation between birds and total prey density was statistically significant at the smallest scale of 5 nautical miles ( n m . ) . the removal of herring from the calculations increased the strength of the correlation. the depth at which prey was located had little effect on the distribution of birds. the correlation between birds and prey was scale dependent, and reached a maximum at 90 n.m., although there seemed t o be some upper threshold in the coefficient at c. 40 n.m. numerical concordance (including only 5 n.m. periods wherc both prey and birds were present) was significant at the 5 n.m. scale but was higher for high density than for low density prey patches. the results are discussed in relation to thc few similar studies in other oceans and in relation to the severe reduction of important prey species in the barents sea. kjell einar erikstad, norwegian institute for nature research, t r o m p museum, university of tromsm, n 9ooo trams@, norway; trulf moum and wim vader, zoology and marine biological departmenls, t r o m p museum, uniuersiv of trams@, n-woo t r a m @ , norway; november 1989 (revised january 1990). feeding seabirds aggregate in large patches with chord lengths of several kilometres (schneider & duffy 1985; schneider & piatt 1986). one likely determinant of these aggregations is that food aggregates at a similar scale (hunt & schneider 1987; schneider & piatt 1986). two main approaches have been applied to test the ‘food aggregation hypothesis’ (see hunt & schneider 1987, hunt this volume and schneider this volume for reviews): 1. to look for correlations between aggre gations of birds and the occurrence of fronts. this method is based on the observations that biological activity increases in areas of water mass boundaries (e.g. f’ingree et al. 1975; emery et al. 1973). 2. to directly correlate numbers of seabirds with the abundance of their prey (obst 1985; schneider & piatt 1986; heinemann et al. 1989). so far numerous studies have related pelagic seabird abundance to the physical properties of the ocean (see hunt & schneider 1987 and schneider this volume for reviews), but only a few have correlated the distribution of birds with their prey (see hunt & schneider 1987 and hunt this volume for reviews). in general, the former show that birds aggregate at fronts, but that fronts explain only a very low fraction of the variance in avian abundance. the few studies of the relationships between seabirds and their prey have shown that the strength of correlation is highly variable (hunt this volume) and that the correlation between birds and prey is stronger at large than at small scales (schneider & piatt 1986; heinemann et al. 1989). the relatively low vari ance of avian abundance explained by fronts may be, as pointed out by schneider (this volume), due to the causal chain linking seabirds to fronts, namely that prey are linked to fronts whereas birds are linked to prey. spatial correlation of marine birds with prey is highly variable, with highest coefficients for larger spatial scales (c. <10 km) and for prey assem blages dominated by a single type of prey 78 k . e . erikstad, t. m o u m & w. vader (schneider & piatt 1986; heinemann et al. 1989). the correlation with assemblages of several prey appears to be low in guillemots (woodby 1984). however, woodby (1984) did not look at cor relation over several spatial scales. this study analyses the correlation of guille mots with prey assemblages over a range of spatial scales. it also compares correlation of guillemots with individual prey species to correlation with the prey assemblage at the same spatial scale. study area observations were made from r/v 'eldjarn' in the barents sea from 29 april to 15 may 1986 along an extended transect of 3,060 nautical miles (5,667 km) in an area ranging from the norwegian coast northward to the ice border at approxi mately 75"n, and from west of bjeirn~ya to west of novaya zemlya (fig. 1). the area is a shallow continental shelf with a mean depth of 230 m and few areas deeper than 400-500m (e.g. loeng 1989). there are three main water masses in the barents sea (e.g. midt tun 1985; loeng 1989; midttun this volume): the norwegian coastal current and the atlantic cur rent which both flow into the barents sea from the southwest and the arctic current system which brings arctic water in from the north. where the arctic and atlantic water meet they mix and form the polar front. the barents sea is an important nursery and feeding area for several commercial fish species such as cod gadus morhua, polar cod boreogadus saida, haddock melanogrammus aeglefinus, her ring clupea harenglls, and capelin mallotus uillosus. capelin is an important prey for both breeding and non-breeding guillemots in the area (belopol'skii 1957; furness & barrett 1985; erikstad & vader 1989). during the non-breeding season, briinnich's guillemots also prey heavily on both gadoid fish and crustaceans (erikstad in press). material and methods bird observations birds were counted from the top of the vessel's bridge (10 m above sea level) in 300 m transects and 10 min. blocks on one side of the ship (tasker et al. 1984). the speed of the ship was about 10 knots, such that counts covered an area of about 0.92 km2 in 10 min. the total number of 10 min. blocks counted was 1,143, covering an area of 1051.6 km2. bird counts were made during the day, usually with a break between 2200-0200 hrs., and also with breaks when the boat was trawling. no attempts were made to count the whole seabird community since some species, e.g. gulls, fulmars fulmarus glacialis, and kittiwakes rissa tridactyla were strongly affected by the trawling activity of the ship (erikstad et al. 1988). we limited the observations to alcid species and bird counts followed the standard procedure suggested by tasker et al. (1984). flying birds were, however, counted continuously and not by divid ing the 10 min. transect into shorter sections. the procedure suggested by tasker et al. (1984) mini mises the problem of repeatedly counting birds circling around the ship. however, because flying alcids only cross the transects and are not affected by the presence of the ship, such effects could be disregarded. bird numbers are probably under estimated since diving birds are not seen and some distant birds may be overlooked. common and briinnich's guillemots were dif ficult to separate at a distance, and only those seen close to the ship were identified to species. 15' 20' 25' 30° js' 400 450 -'p" estimates of prey densities 1 740 i 730 i 70' -1 1 -\ l the ship made quantitative acoustic/trawl survey estimates of the densities of different fish species in the area, according to standard methods. the instrumentation on board r/v 'eldjarn' included simrad ek 400, a digital scase echo-integrator and a nord-10 computer for data storage and analysis, including echo-integration which aggre gated data every 5 nautical miles (n.m.). the echoes produce traces often characteristic fig. 1. map of the study area showing the transect surveyed and the approximate position of the ice edge in april/may 1986. for different prey species or prey categories. on common and brunnich’s guillemots and their prey 79 this basis the integrator values were assigned to different prey categories. this procedure was verified by trawl net samples every 3 m o n.m. or in areas of high integrator values. the prey categories were capelin, herring, polar cod, plankton and mixture. the last category groups together several fish species, the most numerous of which were cod, haddock and redfish sebastes rnarinusls. mentellu. the different prey cate gories were also assigned t o two depth cate gories, 10-100 m and 100-200 m. data analysis prey densities were measured to a minimum scale of 5 n.m., whereas seabirds were counted in tran sects of 10 min. blocks. to enable comparison of seabird and prey data at the minimum scale of 5 n.m., we used two methods. first, maps were drawn of prey and bird distributions, using a grid computer programme which could be varied in size from squares of 20 x 20 km upwards. secondly, to describe the patchiness and distri bution of birds and prey along the continuous transect, we used the maximum number of birds seen within each 5 n.m. period as an index of bird density. regressing total bird numbers against maximum numbers within 30 min. periods (c. 5n.m. when the speed of the ship is 10 knots) showed that nearly all variation in avian density could be explained by this index (r2 = 0.99). the acoustic values of different prey species were used as an index of density only, since more information is needed for estimating absolute fish density (johannesson & mitson 1983). the size distribution of different fish species is a very important factor in determining the suitability of prey to seabirds (swennen & duiven 1977; hulsman 1981). we used a logarithmic scale in the presentation of data and in several analyses we also ranked the data in order to meet the assumptions of the statistical tests. spatial scaling to examine the importance of spatial scale on the correlation between seabird density and prey density we analysed the seabird and prey density estimates from the 5 n.m. periods and then the mean densities were calculated for larger scales by aggregating data over an increasing number of 5 n.m. periods (2-20). the day time counts of birds provided sampling units separated both in space and time. we used all segments longer than 10 x 5n.m. periods (a total of 17 segments, covering a range from 10 to 27 x 5 n.m. periods), and tested for correlation between mean prey and bird density. statistical testing the spatial association between guillemots and prey (defined as the degree to which seabird and prey present are related) was calculated at the 5 n.m. scale. we tested the presence/absence data, and tested for differences in spatial associ ations at different times of the day (4 h blocks), using chi-square tests. to estimate the overall correlation between seabirds and prey, we calculated spearman rank correlations. the data could not be described by standard statistical models (see also schneider & piatt 1986; heinemann et al. 1989), so random ization tests were used to evaluate statistical significance. correlation between seabirds and prey at the 5 n.m. scale was tested for significance by comparing the observed correlation at this scale, r(5) to one hundred values of the same statistic obtained by randomizing 5 n.m. prey data with respect to location. a turbo-pascal random generator was used t o obtain random permutation of prey data. bird data were not randomized in this test. we tested the two following hypotheses (see also schneider & piatt 1986): 1) the null hypothesis, h,:r(5) = 0, was rejected if an observed value of r(5) was greater than 95 of 100 values of r(5) from randomization data, and 2) the null hypothesis (scale independent corre lation), ho: r(5) = r(f), was rejected in favour of the alternative hypothesis, ha:r(5) <r(f), if 95 of 100 randomized values of r(f) were greater than the observed r(5) value. f is spatial scale, taking on values of 2-20 periods of 5 n.m. since densities above the 5 n . m . scale are means of densities pooled within larger sampling units, we tested the correlations at larger scales against the underlying 5 n.m. scale (see heinemann et al. 1989). the numerical correlation (defined as the rank correlation between seabird numbers and prey densities where both are present) was estimated at the 5 n.m. scale only. since numerical association may manifest itself only above some threshold in prey density (piatt 1987; heinemann et al. 1989), 80 k. e. erikstad, t. moum c% w . vader 160 we analysed ‘low density’ and ‘high density’ patches separately. ‘high density’ prey patches were selected according to discontinuities in the distribution of prey densities and in such a way that an appropriate number of 5 n . m . periods was obtained for statistical testing. mar 618 capelin results 240 1 bird densities a total of 8,726 birds were seen within the 1,143 10 min. periods, giving a total of 7.6 birds per km2. briinnich’s guillemots and common guillemots were by far the most common alcid species, and totalled 90.8% of all birds seen. only 38.4% of the guillemots seen could be identified to species, but the ratio of those identified showed that briin nich’s guillemots were by far the most numerous (88.3%). other auks seen were (in decreasing order of abundance): little auk alle alle (5.6%), puffin fratercula arctica (3.1%), razorbill a k a torda (0.1 %) and black guillemot cepphus grylle (0.06%). because of their small number, these four species were left out of the calculations below. of the total number of brunnich’s and com mon guillemots seen (n = 7,919), 61.2% were seen on water and 38.8% flying. in the cal culations of the correlations between birds and prey only birds seen on the water were considered, since flying birds are not necessarily associated with the habitat and their numbers can not be expected to be closely linked to the presence of food. mixture max2218 spatial distribution of guillemots and prey both birds and prey showed a clear non-random distribution where low density patches alternated with high density patches along the transect (fig. 2). of the 388 five nautical mile periods where we had both bird and prey data, birds were present in 275 (70.9%) periods, prey present in 243 (62.6%) and both birds and prey in 173 out of 275 periods (62.6%). the degree of spatial association of birds and prey varied during the day (table 1, 2 = 27.2, df = 4, p < 0.001). it was highest during the day (1000-1400,75%) and lowest at night (0200-0600, the proportion of birds seen on water (and which were presumably feeding (table 1)) varied 21 %) . 8 0 40 -’ 0 i 1.l 1, id 0 sbloolso2i)o250340~400450500556 bw 5 neutlcal mile periods fig. 2. number of common and briinnichs guillcmots and density of different prey categories along a transect in the southern barents sea. throughout the day and night. the maximum occurred when prey and birds were most closely correlated (1000-1400). the overall spatial associations of birds and prey irrespective of time of day were low for single prey categories (range from 8% in herring to 33.8% for capelin (table 2)). between 1000 and 1400 hrs., the association of capelin increased to 58.9%, which differed significantly (2 = common and briinnich’s guillemnts and their prey 81 table i . percentage of common and briinnich’s guillemots seen in the southern barents sea on water (n = total number of birds seen) and the percentage of 5 nautical miles with birds that also had prey present (n = total number of 5 mile blocks with birds within this time period) during 4-h time blocks from 0200-2200 local time. time of day ~~ ~ 0001-0400 0401-0800 0801-1200 1201-1600 1601-2000 (n = 748) (n = 1,081) (n = 3,082) ( n = 1,305) (n = 1,501) (n = 19) (n = 72) (n = 55) (n = 64) (n = 64) birds on water (to) 15.6 54.0 85.9 49.8 46.3 5 mile periods with 21.1 37.5 70.5 65.7 60.9 birds and prey (%) 12.4, df = 1, p < 0.001) from when all time periods were considered, but the association with other single prey categories remained very low. the low spatial association between birds and single prey categories is also obvious from figs. 2 and 3, since birds were distributed in patches along the whole transect while each prey category was restricted to smaller areas with partly non overlapping distributions. most illustrative are the distributions of the schooling species capelin, herring and polar cod, which overlapped very little spatially. capelin were most common in the northwestern part of the study area, while herring and polar cod were distributed to the south and east, respectively (fig. 3). overall correlation and spatial scaling since it is obvious from inspection of the data that no single prey category could explain the distributional patterns of birds, we carried out an exploratory analysis of overall correlation between birds and prey first by combining all five prey categories at both depths and then stepwise removing different combinations of prey cate gories and depths to evaluate combinations where we achieved the highest significant correlation. at the 5 n.m. scale there was a statistically significant correlation between birds and total prey density at depths 100-200m and 10-200m (fig. 4). the coefficients were low (0.14-0.20) but could be increased somewhat ( o . l t m . 2 5 ) by aggregating data on the 10 n.m. scale. coefficients were not significantly higher at larger scales, sug gesting an absence of scale dependent correlation. the removal of herring from the calculations increased the strength of correlation. at the 5 n m . scale, correlations ranged from 0.22-0.29 but were again only signficant at depths 100 200 m and 1&200 m. maximum significant cor relation coefficient was achieved at 100-200 m on a scale of 90 n.m. (0.54) and at 10-200 m on a scale of 80 n.m. (0.50). according to fig. 4, there appears to be some upper threshold in the coef ficients reached around a scale of 40 n.m.(r-values of about 0.43). above 40 n m . the r-values fluc tuated markedly, although maximum significant correlation coefficients were achieved at 80 and 90n.m. for depths 100-200m and 10-200m, respectively. the highest correlation was achieved when using the three prey categories capelin/1@-100 m, mixture/10-100 m and plank ton/10-200 m. these coefficients were signi ficant at all scales, and reached a maximum at 90 n.m. (r = 0.64). overall correlations between seabird and prey density means at the ‘segment’ periods (fig. 5) were strong (r = 0.63). this correlation coef ficient also differed significantly from the under lying 5 n.m. correlation. numerical correlation correlations between birds and prey at the 5 n.m. table 2. the presence of different prey categories (%) in 5 mile periods where birds were present according to different times of day. n = number of 5 n.m. periods. capelin herring polar cod plankton mixture total all times of day (n = 275) 33.8 8.0 15.6 12.4 17.4 62.9 day time (1001-1400) (n = 56) 58.9 7.0 17.9 21.4 28.6 75.0 82 k . e . erikstad, t. mourn & w . vader a 10 a 5 . common o%y 0 1 guillemot 0. 10 m 5 capelln 10 0 5 20 m 10 polar cod plankton . 10 5 mixture fig. 3. the distribution of common and brunnich's guillemots and different prey categories in the southern barents sea. filled circles indicate numbcr of birds/kmz o r m e a n acoustic signal strength/km2 (for diffcrcnt prcy categories). scale when both were present were significant (r = 0.42). the correlations were much higher for discussion high density prey patches (r = 0.71) than for low density patches (r = 0.35), suggesting that spatial distribution of birds and prey numerical concordance between birds a i d prey the association of birds and prey showed a clear may first manifest itself when a threshold is die1 pattern, and was highest during day time reached (fig. 6). these high density prey patches when the largest number of birds was seen on covered only 5.6% of the area studied but the water (presumably feeding birds). accord included as much as 58.2% of all birds seen. ingly, the time of day (die1 feeding rhythm) is an common and brunnich's guillemots and their prey 83 0.6 0.5 0.4 0.5 o.6 i a c /. e ,.-@4 . ' 0.0 ' 0.6 r 0.3 0.2 0.1 0.2 1 " 0.1 , 0.0 0.7 i o : l o l w m d e p t h a : 100 -200 m depth 0 : 10 200 m depth 0.0 ' 0 4 8 12 16 20 frame size (5 n.m.) fig. 4. correlations between guillemots uriu spp. and prey in the southern barents sea at different depths as a function of measurement distance (5 nautical mile periods). a . guillemots and total prey density. b. guillemots and prey when herring is rcmoved from the calculations. c. guillemots and the prey categories which gave the highest correlation cocfficients (cap elin at depth 1&100m, plankton at both depths, and mixture at dcpth 1&100 m). statistical significance is indicated by solid symbols (p < 0.05). important factor which has to be considered when evaluating the correlations between birds and prey. birds on the water include both resting and feeding birds (which are difficult to differentiate), while flying birds are presumably searching for food either by looking for other feeding birds or by spotting surface prey, and are therefore expected to be less associated with prey. woodby (1984), who also addressed this problem in the southeastern bering sea, noted a similar diurnal pattern in the number of guillemots seen on water but he did not evaluate the degree of association between birds and prey at different times of the day. there was no single prey category which alone could explain the distributional patterns of birds. this agrees with recent studies of the diets of seabirds from the barents sea where briinnich's guillemots may feed heavily on both capelin, cod, and crustacea during the non-breeding season (erikstad & vader 1989; erikstad in press). there is less information on the diet of com mon guillemots but they have been shown to prey on capelin close to the breeding colonies during the prelaying season (erikstad & vader 1989). from the open sea there is to date no study, but there is a general acceptance that they rely heavily on capelin also at this time of the year (barrett 1979; vader et al. in press), a suggestion which is in accordance with diet studies from the breeding colonies in this study area (furness & barrett 1985). unfortunately we were not able to evaluate the associations between capelin and the two guillemot species separately, as only a small fraction of birds of the two species could be dif ferentiated. however, there is some evidence that common guillemots may be more strongly associated with capelin than briinnich's guille mots. first, capelin was the single prey species which was most common in areas where birds were located. secondly, the distribution of the few common guillemots identified was similar to the distribution of capelin which covered the northwestern part of the transect system (fig. 3). briinnich's guillemots were distributed through out the area investigated. in the northwestern part they overlapped with the common guillemot but in the eastern part briinnich's guillemots were found alone within the range of polar cod but outside the capelin area. herring was the only prey category which was less associated with birds than initially expected. at first sight this may seem contradictory since herring is known to have been an important nourishment for both guillemot species during summer in the eastern parts of the barents sea (belopol'skii 1957). however, the herring avail able in this study (mean length c. 20 cm with only 84 k . e . erikstad, t. mourn & w , vader rs= 0.63 p < 0.01 . 1 . 1 . . 8 . . . . . . . -1 0 1 2 3 4 5 6 7 prey density index (log.) fig. 5 . overall correlation between mean density of guillemots and prey at the ‘segment’ intervals. 6 1 i r. -0.35 5 p< 0.01 . i . 0 l l l . . . . 8 * . l ~ 0 1 2 3 4 5 prey density index (log. ) r. =0.71 1 p<o.o1 l, 6 7 8 prey denslty lndex(log.) 0 . 5 fig. 6. numerical correlation (where both birds and prey were present) between guillemots and prey in the southern barents sea at low (a) and high (b) density prey patches. avery few specimens less than 18 cm, unpublished data from the norwegian fishery institute) may have been too large for the guillemots to feed on. herring of 20cm length have a body height of c. 45 mm. although common guillemots are able to swallow fish of this size, swennen & duiven (1977) found that they prefer much smaller (c. 12 cm) fish. this result agrees with the observed size range of other fish fed upon by the two guillemot species in the barents sea. erikstad & vader (1989) showed that common and brunnich’s guillemots feed on capelin of c. 15 cm during the prelaying season, which is also con sistent with studies from the breeding season (furness & barrett 1985; barrett & furness unpublished). brunnich’s guillemots feed on 8 12 cm cod and polar cod during winter (erikstad in press), the capelin recorded in this study had a mean size of 15cm (unpublished data from the norwegian fishery institute), suggesting that most of the capelin available were within the appropriate size range for guillemots. we know nothing about the size range of the other prey categories present in this study. spatial scaling and overall correlation at the smallest scale of 5 n.m. there was a signifi cant, albeit low, positive correlation between bird and total prey density. the correlation coefficient increased when herring was removed from the calculation. at spatial scales greater than 5 n.m. the correlations increased and reached a maxi mum at 80n.m. (145 km). however, there appears to be some upper threshold in the cor relation reached at about 3 w o n.m. (54 km). the highest correlation coefficient was achieved when using the prey categories capelin/1@100 m, plankton/10-200 m and mixture/1@100 m. it is difficult to make any reasonable interpretation of this result. presumably it is accidental and caused by some intercorrelations of different prey cate gories. the depth at which different prey categories were distributed had little effect on the strength of the correlation. in fact the coefficient was somewhat higher for the depth range lo(r200 m than for 10-100 m. that birds seem to track prey independent of depth may be a result of several mechanisms. guillemots can dive to depths greater than 100 m (piatt & nettleship 1985; burger & simpson 1986) even though they may common and briinnich’s guillemots and their prey 85 feed in shallower water (barrett & furness unpublished). moreover, young year classes of important prey categories in the barents sea, such as capelin and cod, show diurnal vertical migration patterns and are found near the surface during the day (e.g. belstad et al. 1975). this pattern is consistent with the diurnal variation in birds seen on the water in this study. to draw firm conclusions about the importance of the depth of prey, a detailed study of patches of feeding birds in relation to prey depth is needed. the present study is one of four which have documented a positive correlation between bird and prey density (schneider & piatt 1986; piatt 1987; heinemann et al. 1989). the results pre sented here are also consistent with the other three studies in that the degree of correlation was higher at larger spatial scales. schneider & piatt (1986) described three different mechanisms which may cause reduced correlation at a smaller scale: 1) local avoidance of the dense prey patches, 2) differences in locomotory capacities of birds and prey and 3) ‘sit and wait predation’ by birds within extended aggregations of prey. local avoidance of dense prey patches seems unlikely in this study, since there was a high numerical correlation (where both birds and prey were present) between bird and prey density. we know less about the other two mechanisms but differences in the locomotory capacity of birds and prey may also be of importance in this study. capelin, which is presumably the most important prey for guillemots, migrate from the northern barents sea to the coast of norway and mur mansk (jangaard 1974; setre & g j o s ~ t e r 1975) at the time of year this study was carried out. rapid swimming by capelin schools may make it difficult for birds to track them, especially at night when they are not feeding (see also schneider & piatt 1986). heinemann et al. (1989) mention two other factors which may explain the lower correlation at small scales: 1) most prey patches are unex ploited at any given time and 2) a small number of prey patches are disproportionately important to birds. we know nothing about the exact num ber of prey and bird patches in this study but at the 5 n.m. scale there is no apparent excess of prey patches (fig. 2). such a low number of prey patches in relation to bird patches may be a consequence of the severely reduced stocks of three important fish species in the study area, namely herring, capelin and cod (hamre 1986, 1988; bergstad et al. 1987). this reduction in prey abundance has also recently led to dramatic decreases in the breeding populations of both common and briinnich’s guillemots in the area (vader et al. in press). that some prey patches are more important to birds than others does not seem to be justified in this study. in fact there was a very close positive correlation between the sizes of prey and bird patches above some threshold (numerical con cordance), suggesting that birds are very good at detecting prey and presumably also at evaluating the relative value of prey patches when prey avail ability is low. the results presented by piatt (1987) are interesting in this context. in a study on com mon guillemots and capelin from witless bay, newfoundland, he found evidence for an upper threshold in prey density. maximum correlation between guillemots and capelin was achieved at an intermediate density of capelin. piatt (1987) suggested that the capture rate of prey by birds levelled out at some threshold and that birds could not increase their foraging success further by sel ecting patches above this level. the general prey density in the barents sea was possibly at such a low level that this upper threshold was not reached. strength of correlation the strength of correlation between prey and pelagic seabird density varies greatly in different studies from very low (68%) to very high explained variances (above 90%, schneider & piatt 1986; heinemann et al. 1989). although few studies have been carried out, there appears to be some general trend in the results obtained, as pointed out by hunt (this volume). studies focusing on diurnally foraging alcids and capelin have been more successful in finding positive cor relations (schneider & piatt 1986; piatt 1987) than those focusing on seabirds and krill (obst 1985; heinemann et al. 1989). as pointed out by hunt (this volume), the majority of krill special ists take their prey at night, whereas birds have to be counted during the day. he also mentions the possibility that planktivorous birds are less able to locate the densest prey patches or, alterna tively, that they may not need to seek the densest patches if background densities or the frequency of micro-patches of prey at high densities are sufficiently great (hunt this volume). when comparing results from different studies, 86 k . e . erikstad, t . mourn & w . vader the use of different correlation techniques should be taken into account. schneider & piatt (1986), who have found the highest coefficients (0.88 l . o ) , used the product moment correlation coef ficient. in this study we estimated the spearman rank correlation. calculating the product moment correlation on our data gives an r-value of 0.86 at the 5 n.m. scale, whereas the spearman rank correlation at this scale was only 0.23. however, we felt that the spearman statistic was more appropriate, since the correlation was driven by a few large patches of birds and prey. schneider & piatt (1986) observed that the correlation between birds and prey was only intermittent and repeated surveys were necessary for detection of correlations (see also safina & burger 1985, 1988). they found that the cor relation of birds and capelin was significant in only 6 out of 12 transects ranging in length from 15 to 30km. with this in mind, the r-values obtained in this study along one long transect of nearly 6,000 km are high. the severe reduction of important prey species in the barents sea (hamre 1986, 1988; r ~ t t i n g e n this volume) may have contributed to this result. a strong reduction in populations of prey species may also reduce the number of prey patches and make it more difficult for birds to track prey at sea. this may explain the mass starvation of common guillemots in the study area during the winter of 1987 (vader et al. in press), when the capelin stock was at its lowest level (hamre 1988). however, such a reduction in the number of prey patches may strengthen the correlations between birds and prey, since the number of prey patches which at any time are unexploited may be low. hence, it can be hypo thesized that correlations between birds and prey should decrease when prey density increases. both the capelin and herring stocks are slowly recovering in the barents sea (hamre 1988), which gives us the unique opportunity to test this hypothesis by repeating counts along such an extended transect during the years of recovery. conclusion and management implications hunt (this volume) mentions three assumptions which are implicit in the hypothesis that predators should aggregate where prey are most abundant: 1) there is a close coupling between prey abun dance and prey availability, 2) the predators are good at detecting and evaluating the relative value of prey patches and 3) predators do not deplete prey patches prior t o measurement of prey abun dance. all of these assumptions seem to be reasonably well justified in this study. birds and prey were closely coupled especially during the day, and the high numerical correlation between birds and prey suggests that birds were both effective in locating and evaluating the relative value of prey patches. a high numerical correlation also sug gests that the birds had not depleted the prey patches severely before measurement. accord ingly, at a scale of 3wo n.m. the distribution of birds could be predicted fairly well, using data on prey distribution and abundance. in fact about 60% of all birds, which were located within only 5% of the study area, could be closely predicted by extremely high values of prey abundance. predicting the distributional patterns of pelagic seabirds using standard acoustic prey density esti mates has important management implications in areas such as the barents sea, where pelagic fish species are heavily exploited and where both the distribution and density of fish species are closely monitored. however, before drawing any final conclusion about the usefulness of standard prey data in predicting seabird abundance, further studies are needed. repeated surveys should be carried out in years when prey density increases (see discussion above) and further studies should also aim at estimating the predictability of prey patches within larger areas of the ocean. acknowkdgemenfs. ~ we are grateful for the help and co operation of the captain, crew and scientists on board r/v ‘eldjarn’. we also thank v . bakken, k . 0. jacobsen and i . johnsen for help with the bird observations, h . m . iversen for programming and the fisheries research institute in bergen for letting us use their acoustic data on different fish species. david schneider and rob barrett kindly made comments on an earlier draft of this paper and rob barrett also corrected the english. this study was part of a larger project (fobo), studying the pelagic distribution of seabirds and their prey in the barents sea. the study was financed by the norwegian research council for science and the humanities and the o i l companies operating in the barents sea area (okn). references barrett, r . t. 1979: small oil spill kills 10-20,000 seabirds in belopol’skii, l. 0. 1957: ecology of sea colony birdr of the northern norway. mar. poll. bull. 10, 253-255. barents sea (engl. transl. 1961, ipst, jerusalem). common and briinnich’s guillemots und their prey 87 belstad, a. k., nakken, 0. & smestad, 0. m. 1975: inves tigations on die1 vertical migration of 0-group fish in the barcnts sea. fiskdir. skr. ser. hauunders. 16, 229-244. bergstad, 0. a , , jorgensen, t. & dragesund, 0. 1987: life history and ecology of thc gadoid resources of the barents sea. j . fish. res. 5 , 119-161. burger, a . e . & simpson, m. 1986: diving depths of atlantic puffins and common murres. auk 103, 828-830. emcry, k. o., milliman, j . d. & uchupi, e. 1973: physicdl properties and suspended matter of surface waters in the southeastern atlantic ocean. j . sedim. petrol. 43, 822-837. erikstad, k. e. in press: winter diets of 4 seabird species in the barents sea after a crash in the capelin stock. polar biol. erikstad, k. e . , bustnes, j. 0. & jacobscn, 0. 1988: duration of ship-following by kittiwakes rissa tridactyla in the barents sea. polar research 6 , 191-194. erikstad, k. e. & vader, w. 1989: capelin selection by com mon and briinnich’s guillemots during the prelaying season. ornis scand. 20, 151-155. furness, r . w. & barrett, r. t. 1985: the food requirements and ecological rclationships of a seabird community in north norway. ornis scund. 16, 305-313. hamre, j. 1986: bestandsog forvaltningspolitikk for lodde og sild i 1979 og 1980-irene. seminar om barentshuuets ressur ser. rapp. norges fiskarladfiskeridir. haufors kningsinsfitutt, 72-03. hamrc, j 198x: some aspects of the interrelation between the herring in the norwegian sea and the stocks of capelin and cod in the barents sea. unpubl. ices paper c . m . 19881 h : 4 2 . i5 pp. heinemann, d . , hunt, g . l . , jr. & evcrson, i . 1989: thc distributions of marine avian predators and their prey, euphausia superha, in the branfield strait and southern drake passage, antarctica. mar. ecol. prog. ser. 58, 3-16, hulsman, k. 1981: width of gape as determinants of size of prey eaten by terns. emu 81, 29-32. hunt, g . l., jr. 1990: the pelagic distribution of marine birds in a heterogeneous environment. polar research 8, 43 54. hunt, g. l.. jr. & schneider, d. c. 1987: scdlc-dependent processes in physical and biological environment of marine birds. pp. 7-41 in croxall, j. p. (en.): seabird,: feeding biology and role in marine ecosystemc.. cambridge university press, cambridge. jangaard, p. m. 1974: the c d p e h (mallotus uillosus): biology, distribution, exploitation, utilization and composition. bull. fish. res. bd. can. 186, 1-70. johannesson, k. a . & mitson, r. b. 1983: fisheries acoustics. a practical manual for aquatic biomass estimation. f a 0 fish. tech. pap. 240. 249 pp. lneng, h. 1989: ecological features of the barents sea. pp. 327-365 in rey, l. & alexander, v. (cds.): proc. 6th conf. comitd arct. int. may 1985. midttun, l. 1985: formation of dense bottom water in the barents sea. deep sea research 32, 1233-3244. midttun, l. 1990: surface temperatures of the barcnts sea. polar research 8 , 11-16. obst, b. s. 1985: densities of antarctic seabirds at sea and the presence of the krill euphausia superba. auk 102,54&549. piatt, j. f. 1987: behauioural ecology of common murre and atlantic puffin predation on cupelin; implications for p o p u lation ecology. ph.d. thesis, department of biology, mem orial university of newfoundland, st. john’s. piatt, j . f. & nettleship, d. n . 1985: diving depths of four alcids. auk 102; 293207. pingree, r . d . , pugh, p. r . , holligan, p. m. & foster, g. r. 1975: summer phytoplankton blooms and red tides along tidal fronts in the castern barents sea. j . geophys. res. 83, 4659-4667. rottingen, i . 1990: changes in the distribution and abundance of norwegian spring spawning herring and barcnts sea capelin. polar research 8 , 33-42. safina, c. & burger, j . 1985: common tern foraging. seasonal trends in prcy fish densities and competition with bluefish. ecology 6 6 , 1457-1463. safina, c . & burger, j . 1988: ecological dynamics among prey fish, bluefish, and foraging common terns in an atlantic coastal system. in burger, j . (ed.): seabirds and other marine uertebrates. columbia univcrsity press, new y o r k . schneider, d. c. 1990: seabirds and fronts: a brief overview. polar reseurch 8 , 17-21. schneider, d . c. & duffy, d . c. 1985: scalc-dependent varia bility in seahird abundance. mar. ecol. prog. ser. 25, 211 218. schneider, d . c. & piatt, j. 1986: scale-dependent correlation of seabirds with schooling fish in a coastal ecosystem. mar. ecol. prog. ser. 32, 237-246. swennen, c. & duiven, p. 1y77: size of food objects of three fish-eating seabird species: uriu ualge. a k a tordu, and fra tercula arcticu (aves, alcidac). neth. j . sea res. 11, 92-98, saetre, r . & gjoszter, j . 1975: ecological investigations o n thc spawning grounds of the barents sea capelin. fiskdir. skr. ser. hauunders. 16, 203-227. tasker, m . l., hope jones, p., dixon. t. & blakc, b. f. 1984: counting scabirds at sea from ships: a review of methods and a suggestion for a standard approach. auk 101.567-577. vader, w . , barrett, r. t.. erikstad, k. e. & strann, k.-b. in press: differcntial responses of common and thick-hilled murres uria spp. to a crash in the capelin stock in the southern barents sea. studies in auian b i d . woodby, d . a . 1984: the april distribution of murres and prey patches in the bering sea. limnol. oceanogr. 29, 181-188. methane emissions are lower from reindeer fed lichens compared to a concentrate feed research article methane emissions are lower from reindeer fed lichens compared to a concentrate feed kia krarup hansena,b, monica alterskjær sundseta, lars p. folkowa, marte nilsena & svein d. mathiesenc,d,e adepartment of arctic and marine biology, uit—the arctic university of norway, tromsø, norway; bdepartment of social sciences, uit —the arctic university of norway, tromsø, norway; cuarctic ealat institute at international centre for reindeer husbandry, kautokeino, norway; duit—the arctic university of norway, tromsø, norway; esaami university of applied science, kautokeino, norway abstract methane emissions from reindeer (rangifer tarandus tarandus) fed lichens (mainly cladonia stellaris) and a concentrate feed were determined using open-circuit respirometry. the lichen diet was low in crude protein (< 2.6% of dry matter [dm]), starch (6.0% dm) and acid detergent lignin (2.0% dm) compared to the concentrate feed (12.7, 22.5 and 7.2% dm, respectively), and high in neutral detergent fibre (82.2% dm versus 34.8% dm in concentrate feed). the feeds were offered in equal amounts (ca. 0.440 kg dm) 2 h after initiating methane recordings in the respiration chamber. the reindeer were adapted to these diets for > 4 weeks prior to experiments and methane emissions recorded for two separate 23 h periods for each diet. methane emissions increased on average by 0.93 g/h (or by 5.8 times) in the first hour after feeding the concentrate feed, while emissions remained unchanged after the intake of lichens. mean methane emissions from reindeer (n = 5) were 7.5 ± 0.54 (se) g ch4 day −1 when fed lichens, compared to a higher emission (p = 0.001) of 11.2 ± 0.54 g ch4 day−1 on the concentrate diet. the mean proportion of gross energy intake lost as methane was 5.2 ± 0.37% on the lichens and 7.6 ± 0.37%, or some 50% higher, on the concentrate feed. this difference was significant (p < 0.001). our results suggest that it is of environmental importance to preserve the lichens on the tundra and minimize supplementary feeding with concentrate diets, in order to reduce methane emission. keywords respirometry; dietary secondary compounds; energy loss; rangifer tarandus abbreviations aic: akaike information criterion; dmi: dry matter intake; gei: gross energy intake; ro: ruminantiumolleyae clade; sgmt: smithiigottschalkii-millerae-thaueri clade; stpd: standard temperature and pressure dry; uit: uit—the arctic university of norway introduction globally only about 40% of the total ice-free land area is suitable for land agriculture. a further expansion of crop and pasture land or an intensification of agriculture is undesirable because this will contribute to the loss of biodiversity, climate change, increased resource use and pollution. dietary change and decreases in food waste are essential to reduce greenhouse gas emission and provide global food security by 2050 (bajzelj et al. 2014). as much as 8% of the land surface is dominated by lichens, particularly in northern and alpine areas (nash 1996). lichens are well known for their high content of phenolic secondary compounds, synthesized as a defense against consumption by herbivores and uv-b radiation (ingolfsdottir 2002). reindeer (rangifer tarandus), unlike most other ruminants, are able to utilize lichens as an important source of energy and nutrients in winter (norberg et al. 2001; storeheier, mathiesen, tyler & olsen 2002). about 2 million of the world population of reindeer are semidomesticated and herded between natural pastures year around, in a sustainable transhumant system by ethnic minorities in russia and fennoscandia (turi 2002). multiple drivers of environmental and social change can be identified in the reindeer herders’ grazing land in the barents region and more change is expected. infrastructure development is currently the most significant driver of change in land use and climate change is an increasing threat to traditional livelihoods (degteva et al. 2017). as ruminants, reindeer rely on a symbiotic relationship with a diverse microflora of bacteria, ciliate protozoa, anaerobic fungi and methanogenic archaea in their anaerobic rumen and hindgut, to utilize plant cell wall carbohydrates (sundset et al. 2007; sundset et al. 2009a, 2009b). one of the end products of rumen microbial fermentation is methane (ch4). methanogenesis is undertaken by methanogenic archaea, which remove h2 from the fermentation to reduce co2 and form ch4. emitted methane represents a loss of energy to the host animal, and also contributes to the global greenhouse effect (johnson & johnson 1995; moss et al. 2000). ways of modulating the rumen microbiota have been explored as an approach to mitigating methane emission and thereby curtail global warming (eckard et al. 2010; martin et al. 2010). several equations have been developed to predict ch4 production in ruminants using data generated contact monica alterskjær sundset monica.a.sundset@uit.no department of arctic and marine biology, uit—the arctic university of norway, 9037 tromsø, norway polar research 2018, vol. 37, 1505396 https://doi.org/10.1080/17518369.2018.1505396 © 2018 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2018.1505396&domain=pdf by respiration chamber studies of cattle and sheep. the equations are based on dmi, level of feed intake and energy digestibility, digestible carbohydrates, or on a range of other dietary and animal factors (kriss 1930; blaxter & clapperton 1965; moe & tyrrell 1979; holter & young 1992). analysing a data set including 289 means from 52 different studies, ramin & huhtanen (2013) concluded that feed intake is the main determinant of total methane production. furthermore, they showed that ch4 energy as a proportion of gei is negatively related to feeding level and dietary fat concentration and positively related to diet digestibility. dietary carbohydrate composition has only minor effects (ramin & huhtanen 2013). even though huge amounts of data are available on methane emission from sheep and cattle, no data have been published on methane emission from reindeer to date, apart from a pilot study by gotaas & tyler (1994). numbers of rumen methanogens are generally lower in reindeer (sundset et al. 2009b) compared to those found in, e.g., cattle (denman et al. 2007; evans et al. 2009; hook et al. 2009). this might indicate lower methane emission from reindeer, as the density of methanogens in the rumen is directly proportional to the production of methane (denman et al. 2007). the reindeer rumen microbiome is affected by a highly seasonal environment and forage chemistry. the amount of methane produced through rumen microbial digestion is therefore also expected to vary with season and diet. little is known about the methanogenic archaea and what factors influence their diversity, density and methanogenesis in the reindeer rumen (sundset et al. 2009a, 2009b). consequently, the main objective of the present study was to measure and compare methane emission from reindeer on two different diets: one consisting of mixed lichen (mainly cladonia stellaris), the other a commercial concentrate feed based on grain and grass. the diets were chosen because studies have shown that lichens may account for up to 50% of the winter diet of reindeer in some areas (scotter 1967; steen 1968; gaare & skogland 1975; boertje 1984). according to inga (2007), holleman & luick (1977) and skogland (1975), reindeer prefer lichens of the genus cladonia, while concentrate feeds are widely used as supplementary feed among herders in fennoscandia (tyler et al. 2007). the type used here (fk reinfor) is the only one produced for reindeer in norway (josefsen & sundset 2014). materials and methods animals five female semi-domesticated reindeer (1.5–2 yr of age) were used in this experiment. the animals were formerly owned and herded by saami reindeer herders. after collection from their herd in tønsvika outside tromsø in northern norway (69°n, 19°e), the animals were transported to the animal research facilities at the department of arctic and marine biology at uit. on arrival, the reindeer were inspected by a veterinarian, given routine anti-parasite treatment (10 ml ivomec oract [merial]) and tagged with numbered ear tags for identification. between experiments and the feed habituation periods, the reindeer were kept outdoors, or in indoor pens under simulated photoperiod conditions corresponding to 69°n, with ad libitum access to feed (pellets and/or lichens) and water unless otherwise stated. their body mass was frequently measured and their surroundings cleaned daily. as experiments required that animals were handled and placed inside a respirometry chamber, preparatory training and habituation over many months was conducted. all experiments were carried out in winter, with animals in their full winter pelage. respirometry measurements enteric methane emission was measured in an opencircuit respiration chamber system consisting of an aluminium box (1.3 m3) with a transparent front. the box was placed inside a climatic chamber at a temperature of 0°c in order to secure thermoneutral conditions for the animals (nilssen et al. 1984). the outlet air was pulled from a hole through the top of the respiration chamber via a tube that was connected to a negative pressure air pump that provided an airflow of 120–140 l · min−1. air flow was measured with a mass flow meter (type g-40, elster a/g mainz). the flowmeter was checked against a singer dtm-325 volumeter that had been controlled by running known volumes of air from a mechanical spirometer through it. small openings at the bottom rear wall of the chamber allowed fresh inlet air to enter. a fan circulated the air inside the box in order to secure that the respired air from the animal could not leave through the air inlet openings. the concentration of ch4 in both outlet and inlet air was determined using a binos-100 methane analyser (rosemount), to allow calculation of the methane production of the animal. also, the concentration of o2 was continuously monitored with a 3-sa oxygen analyser (applied electrochemistry), mainly to assure that the box was always adequately ventilated. gas temperature (tgas, °c) and relative humidity (%) of the outlet air were recorded using a thermoand hygrometer (vaisala hmi 32), for use in calculation of water vapour content for stpd corrections of gas flow. gas subsamples were drawn from the main air flow tube and fed into a pressure reduction chamber via a small pump (thomas industries), and from 2 k.k. hansen et al. there the gas analysers pulled gas via columns containing a drying agent (calciumchlorid, merck kgaa) for removal of water vapour prior to analysis. before each experiment, the methane analyser was calibrated using a certified aga 99.99% pure n2 as a zero (baseline), and 997 mol-ppm (0.0997%) ch4 in n2 as a reference. the oxygen analyser was calibrated against 99.99% pure n2 and ambient air (20.95% o2) before experiments and then checked manometrically at weekly intervals. analogue signals from all instruments were digitized by an a/d converter (powerlab/16sp, adinstruments), and then recorded as 30-s means on a computer using the programme chart v5 for windows (powerlab, adinstruments). experimental procedures methane emission experiments were carried out with all five reindeer, twice per animal per diet. hence, a total of 10 individual recordings per diet were conducted. the diets were either a concentrate feed containing 23.0% oats, 18.9% timothy grass, 16.0% wheat bran, 11.2% barley, 7.8% beet pulp, 5.0% oat meal flour, 5.0% molasses, 0.8% soya extract, 1.5% vegetable fat and 10% premix including vitamins (a, d3, e, copper, selen) (fk reinfor, felleskjøpet, norway) or mixed lichens (mainly cladonia stellaris) picked in østerdalen, in southern norway. the lichens were kept frozen at −20°c until use. to avoid problems with variable feed intake between individuals during experiments, we offered all animals a limited amount of ca. 0.440 kg dm feed during each experiment, to ensure that there were not feed refusals. the amount of feed was based on our experiences with food intake of the experimental animal during training. we also took into consideration that the feed intake of reindeer under natural conditions is much reduced in winter (larsen et al. 1985). prior to the experiments, the reindeer were given ad libitum access to the relevant feed in a four-week habituation period, to allow both the digestive tract and the gut microflora time to adapt to the feed. the last week before the measurements, the reindeer were given the same restricted amount of feed that was given during the experiment, thereby adapting the animals to the experimental feed rations. as a consequence, the animals lost some body mass during the course of the experiments (table 2). the animals were kept inside approved animal indoor pens at the department during both the habituation and experimental periods. the water contents of the lichens and pellets were determined prior to the experiment, to allow calculation of the wet weight of feed that would correspond to 0.440 kg dm. the feed was kept in plastic bags at −20°c until thawing, 2 h before feeding. pilot experiments showed an immediate response in methane emission to feeding pellets, while it took more than 12 h for methane emission to return to baseline levels (background levels before feed). in order to obtain the best possible estimate of the daily methane emission on each specific diet and daily ration, we aimed to conduct measurements over a full 24 h cycle. however, to allow repeating measurements, change of experimental animal and resetting of equipment, measurements were conducted for 23 h, while the 24th h was extrapolated. as stated above, methane emission was determined twice for each animal on each diet. to allow the animals to rest between experiments, these were not on consecutive days. one measurement with animal no. 10 on the lichen diet was excluded because outlet gas by mistake was not analysed during the first 3 h of that experiment. all experiments started at 09:10. concentrations of ch4 and o2 of the outlet (animal) air were recorded for 50 min every hour, followed by 10 min recording of inlet air concentrations, to determine background gas levels. the average gas concentration was logged every 30 s. the animals were fed 2 h into the experiment, to keep their normal routine, and to allow a 2-h recording of baseline methane levels prior to feeding. water was not offered until about 6 h into the experiment, to avoid spillage of food due to mixing with water. lights were on during all experiments to permit continuous surveillance of the animal via a video camera. body mass was determined before and after each experiment. calculations the mean hourly differences in gas concentrations (δ ch4 and δ o2, in %) between outlet and inlet air were determined based on 50 min of outlet air recording, and the 2 × 10 min of inlet air recording before and after each outlet air recording. on shifting between sampling of outlet and inlet air, 2–5 min passed before the dead space gas in the system had been replaced. therefore, only the last 45 min of the outlet air recording and the last 5 min of the two inlet air recordings were used for hourly gas concentration calculations. the hourly stpd-corrected volume of methane emitted (vch4 (l · h −1)) was calculated as follows: vch4 ¼ δ% ch4 � 0:01 � 60 � flowstpd (1) flowstpd (l· min −1) is the dry air flow at standard temperature ts (273.15 k) and pressure ps (760 mmhg), as recorded with the mass flowmeter and then corrected by subtracting the vapour content of the gas. this was calculated based on the following equation (modified from vaisala 2013): polar research 3 flowstpd ¼ flowstp � ðflow � ððrh=100þ � 4:59 � ð10^ðð7:6 x tgasþ=ð241 þ tgasþþþ=pþ (2) rh is relative humidity (%), tgas is the gas temperature (°c) and p is air pressure (mmhg). the hourly mean amount of methane emitted (mch4; g· h−1) was calculated as follows: mch4 ¼ ps � vch4 � mch4ð þ= r � tsð þ (3) ps, vch4 and ts are as defined above (for eqn. 1), mch4 is the molar mass of ch4 (16.043 g · mole −1) and r is the gas constant (62.36 l · mmhg · k−1 · mole−1). methane emission during the 24th h that was not recorded was estimated as the mean of the emission during the first and the 23rd h. the total daily methane emission (vch4, tot; l · day −1) on the experimental diets was then calculated by summing all hourly emission. gross energy lost as methane was determined by multiplying the total daily stpd-corrected methane emission (vch4, tot; l · day −1) by the energy content of methane (ecch4 = 39.45 kj · l −1) (brouwer 1965; suzuki et al. 2007). daily energy loss by methane emission (ech4), as expressed in % of daily gei, is then: ech4 ¼ vch4; tot � ecch4 � � =gei � � � 100 (4) gei is equal to the product of the calorific value (kj · g−1) of the feed (table 1) and the daily dm intake of the feed (g · day−1), i.e., the ca. 0.440 kg of pellets or lichens that was offered to the reindeer each day. oxygen uptake rates (vo2; lo2 kg −1 day−1) were calculated in the same way as the methane emission rates, based on the stpd-corrected air flow and the difference in o2 concentration between inlet and outlet air and assuming an rq of 1. chemical analyses of the diet prior to each experiment, subsamples from different locations of the feed-storage-container were collected, to obtain representative samples of the feed. the samples were stored at −20°c for later analyses. the water content was determined by weighing each sample before drying (wet weight) and after drying, at first at 60°c, then at 110°c, until completely dry (dry weight). samples were placed in previously dried beakers and stored in containers holding dried silica gel (chemiteknik as) to prevent them from attracting moisture. a mixture of the representative samples from each experiment (400 g pellets, n = 2 and 300 g lichens, n = 3) was used for the chemical analyses that were performed by eurofins food & agro testing norway as. the calorific values of the dry feeds were determined by use of an oxygen bomb calorimeter, type parr 6300 (thermo fisher scientific). the crude protein content was determined according to the kjeldahl method (european commission directive 93/28 m). to determine fat content, 5 g of the sample was covered with a fat-free wad of cotton wool, before extraction with light petroleum for 6 h in an extractor and oven-dried for 1.5 h, followed by weighing. the ash content was determined by gradual heating of the weighed (5 g) samples until carbonization. samples were then placed in a muffle-furnace at 550°c until the ash was white, light grey or reddish. water-soluble carbohydrates were extracted with boiling water. the amounts of glucose and fructose were enzymatically determined after acid hydrolysis (boehringer mannheim 1984). the amount of starch was determined according to the chatteris laboratory of asl food and pharmaceutical using their standard method am/c/401 based upon european commission regulation 152/2009. starch content was corrected subtracting the aqueous alcohol extract reading (sugars) from the total optical rotation figure (starch plus sugars). the range of application is 0.1–100 g/ 100 g. dm was determined for the same samples and numbers are given in percent of dm (% dm). neutral detergent fibre content was determined in ground samples that were weighed before adding 100% neutral detergent solution and sodium sulphite prior to incubation for 16 h in a 90°c oven. amylase was added 1 h before the end of incubation. after filtering through tarred crucibles with fitted discs and washing with water, the crucible was dried overnight and weighed. the neutral detergent fibre content was derived from the weight difference before and after treatment (chai & udén p 1998). acid detergent fibre and acid detergent lignin contents were determined according to robertson & van soest (1981), using the permanganate method, as performed by the department of soil and environment, swedish university of agricultural sciences (skara, sweden). neutral detergent fibre represents the total cell wall content of hemicellulose, cellulose and lignin, while acid detergent fibre is a subcomponent of the neutral detergent fibre, containing cellulose and lignin. the lignin content of the feed is given as acid detergent lignin. table 1. chemical composition of the mixed lichen diet and the concentrate diet (mean ± sd). pellets (n = 2) lichens (n = 3) calorific equivalent (kj· g-1 dm) 18.5 ± 0.05 17.4 ± 0.85 dry matter (%) 88.9 ± 0.10 38.2 ± 1.86 in % of dry matter: crude protein 12.7 ± 0.10 < 2.6a fat 4.7 ± 0.16 1.7 ± 0.16 ash 7.8 ± 0.10 < 2.6 a water-soluble carbohydrates 5.9 ± 0.05 0.1 ± 0.06 starch 22.6 (n = 1) 6.0 (n = 1) neutral detergent fibre 34.8 ± 0.29 82.2 ± 1.13 acid detergent fibre 1.9 ± 0.01 3.4 ± 0.45 acid detergent lignin 7.2 ± 0.21 2.0 ± 0.10 a below the detection level. 4 k.k. hansen et al. statistical analyses the statistical analyses were performed using r 3.4.1 for windows (r development core team 2017). we analysed the variation in methane emission per day, and per day per kg, mass-specific vo2 (resting oxygen uptake rate), and the proportion of gei lost as methane, using identically structured linear mixed models fitted with the lmer function from the lme4 package (bates et al. 2015). specifically, we considered three alternative models with either feed type, feed type and date, or the full factorial term (i.e., feed type × date), as covariates. all models also included a random intercept for ‘“subject id”’ to account for repeated sampling, which improved model fit in all cases (mean ± se δaic: 4.9 ± 1.5). we compared the aic for all original models (fitted with maximum likelihood), and selected the model with the lowest aic as our final model. when δaic for alternative models was < 2, we selected the most parsimonious model as final. we then refitted this model with restricted maximum likelihood (zuur et al. 2009), and calculated degrees of freedom using the satterthwaite approximation (lmertest package; kuznetsova et al. 2017). diagnostics plots confirmed that the model of percentage of gross energy intake lost as methane performed better with an untransformed response variable than with logitor arcsine square root-transformed values (the final model structure did not differ depending on different transformations). body mass variation between feeding treatments was compared in a mixed-effects model (fitted with lmer from the lme4 package) with body mass as the dependent variable, feed type as a fixed factor, and subject id as a random factor. apart from results on feed composition and energy content, which are presented as means ± sd, data in tables and text are least square means ± se (estimated using the lsmeans package; lenth 2016), and all significances are two-tailed. results the concentrate feed produced for reindeer (felleskjøpet, norway) contained high concentrations of crude protein, fat, ash, water-soluble carbohydrates, starch and acid detergent lignin compared to the lichens (mainly cladonia stellaris) diet (table 1). the lichen diet consisted mostly of carbohydrates extracted in the neutral detergent fibre fraction of the chemical analysis (82.2 ± 1.13% of dm), in addition to starch comprising 6.0% dm (table 1). the average body mass and dm feed intake was 61 ± 1.34 kg (n = 5) and 0.434 ± 0.003 kg on the concentrate feed, and 53.4 ± 1.34 kg and 0.450 ± 0.053 kg on the lichen diet (table 2). the reindeer had a similar intake pattern for both diets, and finished their meal within the first hour after feeding either pellets or lichens. table 2. parameter estimates, degrees of freedom, and f and p values for final models. for interactions, estimates represent the slope of the relationship between the dependent variable and the covariate for each of the factor levels. for main effects, estimates are the least squares means as predicted for the final model. for main effects in interaction models, estimates are the least squares means disregarding any other factors/ covariates in the model. degrees of freedom were estimated using the satterthwaite approximation. parameter estimate (se) df f p total methane emission (g d−1) feed (pellets | lichens) 1, 13.54 16.93 0.001 feed = pellets 11.173 (0.542) feed = lichens 7.498 (0.545) julian date (1 = 1 january) −0.049 (0.005) 1, 14.89 4.60 0.049 feed ×× julian date 1, 11.97 8.94 0.011 feed = pellets 0.004 (0.026) feed = lichens 0.111 (0.037) specific methane emission (g kg−1 d−1) feed (pellets | lichens) 1, 14.37 26.15 < 0.001 feed = pellets 0.1834 (0.0095) feed = lichens 0.1405 (0.0097) julian date (1 = 1 january) −0.0006 (0.0001) 1, 14.73 10.70 0.005 feed ×× julian date 1, 12.58 16.65 0.001 feed = pellets 0.0002 (0.0005) feed = lichens 0.0029 (0.0007) specific vo2 (lo2 kg −1 d−1) feed (pellets | lichens) 1, 13.23 35.08 < 0.001 feed = pellets 7.917 (0.205) feed = lichens 6.790 (0.210) proportion gross energy lost as methane (ech4) feed (pellets | lichens) 1, 12.94 107.12 < 0.001 feed = pellets 0.0760 (0.0037) feed = lichens 0.0523 (0.0037) body mass (kg) feed (pellets | lichens) 1, 14.00 99.32 < 0.001 feed = pellets 60.980 (1.341) feed = lichens 53.325 (1.341) polar research 5 methane emission from reindeer increased in response to intake of the concentrate feed, and was elevated for the following 8–12 h, while methane emission from reindeer fed lichens did not increase above baseline levels in response to feeding (fig. 1). the mean methane emission from reindeer fed lichens was 7.5 ± 0.54 g · day−1, compared to 11.2 ± 0.54 g· day−1 from reindeer fed the same dm amount of pellets (table 2). this difference was significant (p = 0.001). there was also a difference (p < 0.001) between the two feeds when methane loss was expressed in terms of energy loss in % of gei (ech4; %): lichens: 5.2 ± 0.37%; pellets: 7.6 ± 0.37%. calculated as methane yield, the reindeer fed pellet emitted 25.7 ± 1.24 g/kg dmi, while the reindeer fed lichens emitted 16.6 ± 1.21 g/kg dmi. there was a clear interaction effect (f = 8.94, p = 0.011) between feed and (julian) date while the animals were fed lichens (table 2). the oxygen concentration of the outlet air never dropped below 20.48%, showing that the respiration chamber was well ventilated at all times. the mean mass-specific oxygen uptake rate (vo2) was significantly higher (f = 35.08, p < 0.001) when the reindeer were fed pellets (7.92 ± 0.20 lo2 · kg −1 · day−1) than when fed lichens (6.8 ± 0.21 lo2 · kg −1 · day−1). discussion this study has shown that reindeer fed lichens emitted significantly less methane compared to when fed concentrate pellets in equal (dm mass) or equi-caloric amounts (table 2), even when the lesser body mass of lichens-fed animals was taken into account (methane emission was 0.1834 g/day/kg body mass on a pellets diet versus 0.1405 g/day/kg body mass on a lichen diet [f = 26.15, p < 0.001]). several factors may have caused this difference. secondary phenolic compounds in the diet, energy intake and relative proportions of volatile fatty acids in the rumen all have the potential to influence methane production in ruminants (lawler 2001). more than 600 different secondary compounds have been reported in lichens, including a large amount of the antibiotic usnic acid (sundset et al. 2010). such plant secondary metabolites may have a direct toxic effect on the rumen methanogens or their symbiotic protozoa and thereby contribute to reduce methane emission (bodas et al. 2012). a mixed lichen diet dominated by cladonia stellaris, such as the one fed to our reindeer in this present study may contain as much as 9.1 mg x g-1 dm of the secondary compound usnic acid (sundset et al. 2010). microbial fermentation in the reindeer rumen has been shown to allow detoxification of dietary secondary compounds (sundset et al. 2008; sundset et al. 2010), but the mechanistic effects of lichens on methanogens and thereby on emission of methane from reindeer remain unknown. a recent study by salgado-flores et al. (2016), examining the effect of lichens consumption and the consumption of a concentrate feed on the rumen and caecum microbiotas in reindeer, showed that the overall density of methanogens was independent of diet. the archaeal and bacterial diversity differed significantly in both compartments, depending on diet (salgado-flores et al. 2016). these altered methanogen and bacterial profiles may explain the significantly lower methane emission from reindeer fed lichens compared to when fed concentrate pellets. we know from other ruminants that methanogens belonging to the genus methanobrevibacter are predominant in the rumen (king et al. 2011). methanobrevibacter-related sequences are distributed between two major clades, figure 1. mean hourly methane emission rates (± s.d.) (gch4· h −1) by reindeer (n = 5) during 24h (data for the last hour extrapolated). the reindeer were fed 2 h into the experiment (arrow), with a concentrate feed (solid line/closed symbols) or a mixture of lichens (dashed line/open symbols). 6 k.k. hansen et al. the sgmt clade and the ro clade (king et al. 2011; stpierre & wright 2012). sequences within a host tend to group phylogenetically either within the sgmt or the ro clade, so that hosts with a large representation of the sgmt group, typically have lower representation of the ro group and vice versa. salgado-flores et al. (2016) found a decreased ratio between methanogens of the sgmt clade and methanogens of the ro clade with the ingestion of lichens in reindeer, suggesting an increased proportion of ro-methanogens associated to lower ch4 output as discussed in other ruminants. furthermore, salgado-flores et al. (2016) demonstrated a lower abundance of predicted genes associated with ch4 metabolism in lichen-fed reindeer, supporting our findings that methane emissions are reduced in lichen-fed reindeer. both nitrogenous compounds and carbohydrates are needed to produce microbial cells, volatile fatty acids and methane (wolin & miller 1988; ørskov 1992; moss et al. 2000). the different proportions of these in the lichens and pellets (table 1) could therefore also explain the observed difference in methane emission. for example, an increased intake of starch often decreases methane emissions (johnson & johnson 1995). in the present study, lower methane emissions were observed in reindeer fed lichens compared to concentrate pellets. lichens consist of many different carbohydrate fractions, with large differences in composition between the different species eaten by reindeer (svihus & holand 2000). lichenin, also known as lichenan or moss starch, is a chemically complex glucan, occurring in certain species of lichens. some lichens are high in lichenan, e.g., cetraria islandica (27% of dm) and c. nivalis (18% of dm). these were both part of our lichen diet in addition to larger amounts of cladonia stellaris, which contains less lichenan (0.1% of dm; svihus & holand 2000). our chemical studies (table 1) showed that the lichens mix used in our study contained 6.0% dm starch. on the other hand, fermentation of proteins typically results in less volatile fatty acids compared to fermentation of carbohydrates (sveinbjörnsson et al. 2006). less methane would therefore be expected to be produced on the more protein-rich pellets diet (12.7% of dm; table 1). this was not the case in the present study, possibly because of the much lower protein content in lichens (< 2.6% of dm), which may have been too low to sustain sufficient microbial growth, thereby causing lower fermentation and low methane production. lichen’s protein content is too low to allow reindeer to maintain a net balance of protein, so the animal has to mobilize body proteins and therefore loses body mass, as normally seen in late spring in reindeer (mcewan & whitehead 1970), compared to when they were fed pellets in january/march. hence, reindeer require a combination of lichens and vascular plants to maintain a stable body mass in winter. wintergreen parts of graminoids contain 10% protein, approximately the same amount as concentrate feed (storeheier et al. 2002). this additional nitrogen source on natural pastures may prevent mobilization of muscle protein, but might also affect the methane emission from reindeer differently from when measured here on the lichen diet. the results of the present study can, of course, not be directly extrapolated to free-ranging animals on natural pastures, because of the different feeding conditions, diet and intake. for example, studies of other ruminants have shown that methane emission increases with increasing intake (blaxter & clapperton 1965). great variability in methane emission across successive days has been noticed in multiday trials and is to a great extent related to variable intake of food (e.g., jonker et al. 2016). in the present study we did not record methane emission during consecutive days, but rather for two individual days per animal per diet. in contrast to many other studies, we standardized the level of intake to a given amount of food so that all of it was eaten in one batch at the beginning of each experiment. this removed the factor of dmi, which is a main determinant of total methane production in ruminants (ramin & huhtanen 2013). methane energy losses relative to gei may vary between 2 and 15% in other domesticated ruminants, but mainly range between 5 and 6.5% (blaxter & clapperton 1965; holter & young 1992; johnson & ward 1996). our data from reindeer were within (for lichens) or slightly above (for concentrate feed) this range. the variable methane emission from different ruminants may, of course, be related to species and body size, but also to dietary compositions, differences in gut anatomy and differences in their gut microbiomes (blaxter & clapperton 1965). in order to compare methane emission from reindeer with those from other herbivores further, we have also performed a pilot study with an identical experimental set-up and design, using norwegian sheep (ovis aries). our study of sheep also indicated a depression in mean methane emission in relation to gei, from sheep (n = 2) fed lichens (2.8 ± 1.0%) compared to sheep eating the concentrate reindeer feed (5.0 ± 0.9%) (nilsen 2013). in both reindeer and sheep, the methane emission rate increased markedly after intake of the concentrate feed, while intake of lichens did not cause any detectable change to the basal emission rate. comparing ch4 emission between different diets and even more so between different studies is challenging because data on methane emission are presented using different units. we have presented our data in g ch4/day and ch4 in % of gei (ech4) (table 2). ech4 relates methane emission to the energy intake and hence to the chemistry (energy polar research 7 contents) of the feed, and to the amount of feed eaten, but does not take into account, e.g., differences in the in vivo dm digestibility of the different feeds. when the digestibility of energy increases, energy lost as methane also increases (blaxter & clapperton 1965). we know that the reindeer rumen microflora has evolved to degrade/detoxify lichen secondary compounds, and that reindeer are highly adapted to utilize lichens as a substrate for nutrients (sundset et al. 2008; sundset et al. 2010; glad et al. 2014). in the present study, we used a lichen diet dominated by cladonia stellaris but also containing small amounts of other lichen species included in the winter diet of reindeer. storeheier et al. (2002) showed that the chemical composition and the in vitro digestibility of lichens eaten by reindeer varies considerably. however, in vivo digestibility of mixed lichens, consisting primarily of c. stellaris similar to our lichen diet, has been found to be high in reindeer (69–81% dm digestibility) (jacobsen & skjenneberg 1975, 1979; øksendal 1994). although we do not know the dm digestibility of the concentrate feed presently used, we do know from previous studies that the in vitro dm digestibility of rf-80 (a concentrate reindeer feed from the same company—felleskjøpet— resembling the reindeer feed used in our study) was 60.7% (storeheier et al. 2002). hence, digestibility studies of lichens in reindeer show that the utilization is high (69–81%), possibly even higher than that of the concentrate diet. assuming a higher digestibility of lichens than that of pellets, reindeer need to eat less lichens than pellets to gain the same amount of energy and methane emission would be even higher on pellets compared to lichens than if only ech4 values are compared between the diets (i.e., 58% higher instead of ca. 50% higher, as we now report). a higher content of starch in the concentrate feed compared to the lichen diet (table 1) may also in part explain the significantly higher output of methane by our pellet-fed animals (table 2). when the residence time in the rumen decreases with the increasing passage rate, the time available for microbial fermentation decreases and so does methane production. rapid passage rate also favours propionate production (moss et al. 2000). since the rumen turn-over time in reindeer fed lichens is long (23–69 h according to aagnes & mathiesen 1994), the passage time does not seem to explain the low methane production in reindeer fed lichens. furthermore, johnson et al. (1996) found that pelleting of forages decreases the methane production, as a result of an increase in passage time (le-liboux & peyraud 1999). however, these effects are not apparent when food intake is restricted, as it was in our experiments. in conclusion, methane emission from reindeer was lower when fed a lichen diet compared to a diet of pellets feed normally used for supplementary feeding. this may be due to the low nitrogen content or the antimicrobial components of the lichens. supplementary feeding has increased in saami reindeer husbandry to ameliorate difficult winter condition, which is crucial for reindeer survival and production (tyler et al. 2007). this study indicates that reindeer emit less methane when eating lichens instead of concentrate feed. acknowledgements we are grateful to the staff of animal caretakers, hans lian, hans arne solvang and john ness, for their help in relation to the experiments. we thank post-doctoral fellow andreas nord for help with the statistics, prof. oddmagne harstad for helpful advice and constructive discussions and lorenzo ragazzi for technical assistance in connection with the experiments. disclosure statement no potential conflict of interest was reported by the authors. funding this study is linked to the framework of the international polar year as part of the consortium project #399 ealat: climate change and reindeer husbandry. funding was provided by the reindeer husbandry research fund. the publication charges for this article have been funded by a grant from the uit publication fund. ethics statement reindeer (rangifer t. tarandus) are not an endangered or a protected species, and no specific permission was required to buy and transport the animals to uit. the transport of the animals took 30 min. all animal experiments were conducted after arrival to uit, in the approved animal research facilities of the department of arctic and marine biology (approved by the norwegian food safety authority, approval no. 089). all procedures were approved by the norwegian animal research authority (permit nos. 3524 and 4003), and the ethics guidelines for research developed by the international centre for reindeer husbandry were implemented. references aagnes t.h. & mathiesen s.d. 1994. food and snow intake, body mass and rumen function in reindeer fed lichen and subsequently starved for 4 days. rangifer 14, 33–37. bajzelj b., richards k.s., allwood j.m., smith p., dennis j. s., curmi e. & gilligan c.a. 2014. importance of fooddemand management for climate mitigation. nature climate change 4, 924–929. bates d., maechler m., bolker b. & walker s. 2015. fitting linear mixed-effects models using lme4. journal of statistical software 67, 1–48. 8 k.k. hansen et al. blaxter k.l. & clapperton j.l. 1965. prediction of the amount of methane produced by ruminants. british journal of nutrition 19, 511–522. bodas r., prieto n., garcía-gonzález r., andrés s., giráldez f.j. & lópez s. 2012. manipulation of rumen fermentation and methane production with plant secondary metabolites. journal of animal feed science and technology 176, 78–93. boehringer mannheim. 1984. methods of enzymatic food analysis using test combinations. methods for food analysis. mannheim, germany: boehringer mannheim gmbh. boertje r.d. 1984. seasonal diets of the deali caribou (rangifer tarandus granti) herd, alaska (usa). arctic 37, 161–165. brouwer e. 1965. report of sub-committee on constants and factors. in k.l. blaxter (ed.): proceedings of the 3rd symposium on energy metabolism. pp. 441–443. london: academic press. chai w.h. & udén p. 1998. an alternative oven method combined with different detergent strengths in the analysis of neutral detergent fiber. journal of animinal feed science and technology 74, 281–288. degteva a., oskal a., mathiesen s.d., burgess p., aslaksen i., johnsen k., magga a.-m., van rooij w., brattland c., corell r., dubovtsev a., garnåsjordet p.a., holmberg a., klokov k., maynard n.g., nellemann c., niillas b., partapuoli p.j., pogodaev m., reinert e., sandström p., slepushkin i., smuk i.a., steffanson j., strogalschikova z., tyskarev a. & westerveld l. 2017. indigenous peoples’ perspectives. in: amap 2017. adaptation actions for a changing arctic: perspectives from the barents area. pp. 167–194. oslo: arctic monitoring and assessment programme. denman s.e., tomkins n.w. & mcsweeney c.s. 2007. quantification and diversity analysis of ruminal methanogenic populations in response to the antimethanogenis compound bromochloromethane. fems microbiology ecology 62, 313–322. eckard r.j., grainger c. & de klein c.a.m. 2010. options for the abatement of methane and nitrous oxide from ruminant production: a review. livestock science 130, 47–56. evans p.n., hinds l.a., sly l.i., mcsweeney c.s., morrison m. & wright a.-d.g. 2009. community composition and density of methanogens in the foregut of the tammar wallaby (macropus eugenii). applied and environmental microbiology 75, 2598–2602. gaare e. & skogland t. 1975. wild reindeer food habits and range use at hardangervidda. in f.e. wielgolaski (ed.): ecological studies, analysis and synthesis. fennoscandian tundra ecosystem. pp. 195–205. berlin: springer. glad t., barboza p., mackie r.i., wright a.-d.g., brusetti l., mathiesen s.d. & sundset m.a. 2014. dietary supplementation of usnic acid, an antimicrobial compound in lichens, does not affect rumen bacterial diversity or density in reindeer. current microbiology 68, 724–728. gotaas g. & tyler n.j.c. 1994. methane production and the doubly labelled water method in reindeer (rangifer tarandus tarandus). proceedings of the society of nutrition physiology 3, 181. holleman d.f. & luick j.r. 1977. lichens species preference by reindeer. canadian journal of zoology 55, 1368–1369. holter j.b. & young a.j. 1992. methane production in dry and lactating dairy cows. journal of dairy science 75, 2165–2175. hook s.e., northwood k.s., wright a.-d.g. & mcbride b. w. 2009. long-term monensin supplementation does not significantly affect the quantity or diversity of methanogens in the rumen of the lactating dairy cow. applied and environmental microbiology 75, 374–380. inga b. 2007. reindeer (rangifer tarandus tarandus) feeding on lichens and mushrooms: traditional ecological knowledge among reindeer-herding sami in northern sweden. rangifer 27, 93–106. ingolfsdottir k. 2002. usnic acid. phytochemistry 61, 729–736. jacobsen e. & skjenneberg s. 1975. some results from feeding experiments with reindeer. in j.r. luick et al. (eds.): proceedings of the first international reindeer/caribou symposium. pp. 95–107. fairbanks: university of alaska. jacobsen e. & skjenneberg s. 1979. experiments with different diets fed to reindeer. scientific reports. agricultural college of norway 58, 1–11. johnson d.e. & ward g.m. 1996. estimates of animal methane emissions. environmental monitoring and assessment 42, 133–141. johnson k.a. & johnson d.e. 1995. methane emissions from cattle. journal of animal science 73, 2483–2492. jonker a., molano g., koolaard j. & muetzel s. 2016. methane emissions from lactating and non-lactating dairy cows and growing cattle fed fresh pasture. animal production science 57, 643–648. josefsen t.d. & sundset m.a. 2014. fôring og fôringsbetingende sjukdommer hos rein. (feeding and feed-related diseases among reindeer.) norsk veterinærtidsskrift 2, 163–171. king e.e., smith r.p., st-pierre b. & wright a.-d.g. 2011. differences in the rumen methanogen populations of lactating jersey and holstein dairy cows under the same diet regiment. applied and environmental microbiology 77, 5682–5687. kriss m. 1930. quantitative relations of the dry matter of the food consumed, the heat production, the gaseous outgo, and the insensible loss in body weight of cattle. journal of agricultural research 40, 283–295. kuznetsova a., bruun p. & bojesen christensen r.h. 2017. lmertest: tests in linear mixed effects models. r package version 2.0–32. https://rdrr.io/github/alku86/lmertest/. larsen t.s., nilsson n.ö. & blix a.s. 1985. seasonal changes in lipogenesis and lipolysis in isolated adipocytes from svalbard and norwegian reindeer. acta physiologica scandinavia 123, 97–104. lawler j.p. 2001. heat increment and methane production by muskoxen fed browse. phd thesis, university of alaska fairbanks. le-liboux s. & peyraud j.l. 1999. effect of forage particle size and feeding frequency on fermentation patterns and sites and extent of digestion in dairy cows fed mixed diets. animal feed science and technology 76, 297–319. lenth r.v. 2016. least-squares means: the r package lsmeans. journal of statistical software 69, 1–33. martin c., morgavi d.p. & doreau m. 2010. methane mitigation in ruminants: from microbe to the farm scale. animal : an international journal of animal bioscience 4, 351–365. mcewan e.h. & whitehead p.e. 1970. seasonal changes in the energy and nitrogen intake in reindeer and caribou. canandian journal of zoology 48, 905–913. moe p.w. & tyrrell h.f. 1979. methane production in dairy cows. journal of dairy science 62, 1583–1586. moss a.r., jouany j.p. & newbold j. 2000. methane production by ruminants: its contribution to global warming. annales de zootechnie 49, 231–253. polar research 9 https://rdrr.io/github/alku86/lmertest/ nash t.h. iii 1996. lichen biology. cambridge: cambridge university press. nilsen m. 2013. ernæringsbasert matproduksjon hos sau. (nutrition-based food production in sheep.) master's thesis, department of biology, uit—university of tromsø: norway. nilssen k.j., sundfjord j.a. & blix a.s. 1984. regulation and metabolic rate in svalbard and norwegian reindeer. american journal of physiology, regulatory integrative comparative physiology 247, r837–r841. norberg h., maijala v. & nieminen m. 2001. palatability and nutrient composition of plants, fungi and lichens foraged by reindeer. programme and abstracts 11th nordic conference on reindeer research, kaamanen 18–20 june 2001. rangifer report 5, 66–67. ørskov e.r. 1992. protein nutrition in ruminants. london: academic press limited. øksendal h. 1994. lav og rundballeensilert engsvingel som krisefór til reinkalvar, innverknad på mage-tarm anatomien og evnen til cellulose gjæring. (lichen and baled meadow fescue silage as an emergency food for reindeer calves; influence on the gastrointestinal anatomy and the ability to ferment cellulose.) tromsø: norwegian college of agriculture/university of norway. r development core team. 2017. r: a language and environment for statistical computing. vienna: r foundation for statistical computing. ramin m. & huhtanen p. 2013. development of equations for predicting methane emissions from ruminants. journal of dairy science 96, 2476–2493. robertson j.b. & van soest p.j. 1981. the detergent system of analysis and its application to human foods. in w.p.t. james et al. (ed.): the analysis of dietary fiber in food. pp. 123–158. new york: marcel decker. salgado-flores a., hagen l.h., ishaq s.l., zamanzadeh m., wright a.-d.g., pope p.b. & sundset m.a. 2016. rumen and cecum microbiomes in reindeer (rangifer tarandus tarandus) are changed in response to a lichen diet and may affect enteric methane emissions. plos one 11, e0155213, doi: 10.1371/journal.pone.0155213. scotter g.w. 1967. the winter diet of barren-ground caribou in northern canada. field naturalist 81, 33–39. steen e. 1968. some aspects of the nutrition of semi-domestic reindeer. in m.a. crawford (ed.): comparative nutrition of wild animals. symposia of the zoological society of london. vol. 21. pp. 117–128. london: academic press. storeheier p.v., mathiesen s.d., tyler n.j.c. & olsen m.a. 2002. nutritive value of terricolous lichen for reindeer in winter. lichenologist 34, 247–257. storeheier p.v., mathiesen s.d., tyler n.j.c., schjelderup i. & olsen m.a. 2002. utilization of nitrogenand mineral-rich vascular forage plants by reindeer in winter. journal of agricultural science 139, 151–160. st-pierre b. & wright a.-d.g. 2012. molecular analysis of methanogenic archaea in the forestomach of the alpaca (vicugna pacos). bmc microbiology 12(1), article no. 1, doi: 10.1186/1471-2180-12-1. sundset m.a., barboza p.s., green t.k., folkow l.p., blix a.s. & mathiesen s.d. 2010. microbial degradation of usnic acid in the reindeer rumen. naturwissenschaften 97, 273–278. sundset m.a., edward j.e., cheng y.f., senosiain r.s., fraile m.n., northwood k.s., præsteng k.e., glad t., mathiesen s.d. & wright a.-d.g. 2009a. molecular diversity of the rumen microbiome of norwegian reindeer on natural summer pasture. microbial ecology 57, 335–348. sundset m.a., edward j.e., cheng y.f., senosiain r.s., fraile m.n., northwood k.s., præsteng k.e., glad t., mathiesen s.d. & wright a.-d.g. 2009b. rumen microbial diversity in svalbard reindeer with particular emphasis on methanogenic archaea. fems microbiology ecology 70, 553–562. sundset m.a., kohn a., mathiesen s.d. & præsteng k.e. 2008. eubacterium rangiferina, a novel usnic acid-resistant bacterium from the reindeer rumen. die naturwissenschaften 95, 741–749. sundset m.a., præsteng k.e., cann i.k.o., mathiesen s.d. & mackie r.i. 2007. novel rumen bacterial diversity in two geographically separated sub-species of reindeer. microbial ecology 54, 424–438. suzuki t., mccrabb g.j., nishida t., indramanee s. & kurihara m. 2007. construction and operation of ventilated hood-type respiration calorimeters for in vivo measurement of methane production and energy partition in ruminants. in h.p.s. makkar & p.e. vercoe (eds.): measuring methane production from ruminants. pp. 125–135. dordrecht: springer. sveinbjörnsson j., hutanen p. & udén p. 2006. the nordic dairy model karoline— development of vfa submodel. in e. kebreab et al. (ed.): nutrient digestion and utilisation in farm animals: modelling approaches. pp. 1–14. wallington, uk: cab international. svihus b. & holand ø. 2000. lichen polysaccharides and their relation to reindeer/caribou nutrition. journal of range management 53, 642–648. turi j.m. 2002. the world reindeer livelihood current situation, threats and possibilities. in s. kankaanpää et al. (ed.): northern timberline forests: environmental and socio-economic issues and concerns. finnish forest research institute research paper. vol. 862. pp. 70–75. helsinki: finnish forest research institute. tyler n.j.c., turi j.m., sundset m.a., strøm bull k., sara m.n., reindert e., oskal n., nellemann c., mccarthy j. j., mathiesen s.d., martello m.l., magga o.h., hovelsrud g.k., hanssen-bauer i., eira n.i., eira i.m. g. & corell r.w. 2007. saami reindeer pastoralism under climate change: applying a generalized framework for vulnerability studies to a sub-arctic social–ecological system. global environmental change 17, 191–206. vaisala 2013. humidity conversion formulas. calculation formulas for humidity. helsinki: vaisala oyj. wolin m.j. & miller t.l. 1988. microbe-microbe interactions. in p.n. hobson (ed.): the rumen microbial ecosystem. essex: elsevier. zuur a.f., ieno e.n., walker n.j., saveliev a.a. & smith g. m. 2009. mixed effects models and extensions in ecology with r. new york: springer. 10 k.k. hansen et al. https://doi.org/10.1371/journal.pone.0155213 https://doi.org/10.1186/1471-2180-12-1 abstract introduction materials and methods animals respirometry measurements experimental procedures calculations chemical analyses of the diet statistical analyses results discussion acknowledgements disclosure statement funding ethics statement references the thermal structure of hansbreen, a tidewater glacier in southern spitsbergen, svalbard jacek jania, dariusz mochnacki and bogdan g 4 d e k jania, j., mochnacki, d. & ggdek, b. 1996: the thermal structure of hansbreen, a tidewater glacier in southern spitsbergen, svalbard. polar research !s(z), 53-66. ice temperature measurements were taken from three shallow and five deep (to bedrock) boreholes on hansbreen, svalbard, in selected years between 1988 and 1994. in general, results show a subpolar, polythermal structure. the glacier accumulation zone is of warm ice within the entire vertical profile except in the uppermost layer of seasonal temperature fluctuations where there is an upper cold ice layer in the ablation zone which vanes in thickness and may even be absent in the western lateral part. the upper layer of cold ice thins along the glacier centre-line from the equilibrium line altitude down to the glacier front. the depth of the pressure melting, indicating the base of the cold ice layer, was defined at the borehole measurement sites but was not manifested as an internal reflection horizon using multi-frequency radar methods. the isotherm lies about 20 m above a radar internal reflecting horizon near the equilibrium line altitude and about 40 m above it in the frontal part of the glacier. the internal reflection horizon almost certainly reflects the high water content within temperate ice and not the cold/temperate ice interface. at 1 0 m depth, the temperatures are 2-3°c higher than the calculated mean annual air temperatures, demonstrating the importance of meltwater refreezing on the release of latent heat. j . jania and b . gpdek, department of geomorphology, faculty of earth sciences, university of silesia, ul. bpdziriska 60,41-200 sosnowiec, poland; d . mochnacki, geographisches institur e t h , winterthurerstrasse iw, ch-8057 zurich, switzerland. introduction svalbard glaciers have been recognised as sub polar in temperature structure since the classifi cation of ahlmann (1935), where a layer of cold ice is underlain by temperate ice at temperatures at the pressure melting point. the thickness of the cold layer generally increases from the equi librium line down to the glacier terminus. this traditional view of the longitudinal temperature distribution within a spitsbergen glacier was out lined by schytt (1964) and, with respect to the consequences for glacial hydrology, discussed by baranowski (1977). however, both direct and indirect data from svalbard glaciers suggest that his picture of the thermal structure of different glaciers in the archipelago is more complicated than previously suspected (e.g. jania 1988). the term “polythermal glacier”, introduced by fowler & larson (1978) and developed by blatter (1990), is particularly relevant to the glaciers of svalbard. a combination of data from temperature measurements and radio-echo soundings from glaciers in northwestern spitsbergen shows that the relatively small and thin (<150 m) b r ~ g g e r breen is cold and frozen to its bed along its entire length. the thicker lovknbreen is tem perate in the middle and higher parts but cold and frozen to its bed in the ablation area. kongs vegen has a temperate accumulation zone and an 8&100 m-thick cold layer below the equilibrium line (hagen 1992). a strong internal reflector of radar signals from the interface between cold and temperate ice (with significant free water content) has been stressed at a number of glaciers (dowdeswell et al. 1984; maeeret & zuravlev 1985; bamber 1987) and later supported by direct borehole measurements of temperature (c.f. hagen 1992). this paper describes studies of ice temperature variations in hansbreen, a tidewater glacier in southern spitsbergen, and discusses the results in the context of the thermal character of other svalbard glaciers and ice caps (fig. 1). although the general model of the thermal structure of svalbard glaciers put forward here is not new, the studies reported in this paper provide additional information regarding ice temperatures within a tidewater glacier and emphasise unusual features in their distribution. 54 j . jania, d. mochrzacki & b. gpdek arated from each other by rock sills rising up to depths of -50 m . t h e ice thickness in the western tributary glaciers exceeds 200 m. t h e mass balance of hansbreen has been measured since the winter season of 1988/1989. in recent years t h e mean equilibrium line altitude has varied between 320 m a.s.1. and 370 m a.s.1. superimposed ice layers have been observed within and near the equilibrium line altitude zone each year. i n 1989, t h e equilibrium line altitude lay a t 325 m a.s.1. and t h e accumulation area ratio (aar) was 0.46. in 1988/1989 the average winter balance was +0.97 m w.e., t h e summer balance 1.15 m w.e., and the average net surface balance was -0.18 m w.e. if the mass loss d u e t o iceberg calving is taken into consideration, the corrected average net balance is about -0.53 m w.e. the dynamics of t h e lower part of the glacier have been monitored systematically by means of terrestrial photogrammetry since 1982 (jania & kolondra 1982; jania 1988). t h e glacier surface velocity in t h e profile located ca. 0.5 k m from the ice cliff is about 60 m a ’ (averaged for the profile). i n the upper part of the ablation zone, t h e velocity is about 30 m a ’ a t the centre-line. glacier velocity accelerates significantly towards the terminal ice cliff. t h e average velocity near t h e terminus profile exceeds 210 m a-’. the mean annual calving speed is about 250 m a-l and annual calving flux amounts t o 22 x lo6 mz of ice. fig. i . svalbard, location map of hansbreen and the glacicrs studied with respect to ice temperatures (table 5 ) : v = vestfonna, hg = hoghetta, hi = holtedahlfonna, k = kongs vegen. be = bertilbreen, l = lornonosovfonna, n = nor denskioldbreen. b = brbgerbreen, f = fridtjovbreen, a = amundsenisen. a general description of hansbreen hansbreen is a grounded tidewater glacier which flows into the fjord of hornsund, southern spits bergen (figs. 1 and 2). t h e glacier covers an area of about 57 km2 and its length is about 16 km. t h e mean slope angle of t h e glacier is 1.5”. t h e glacier tongue is about 2.5 km wide and ter minates as a 1.5 km long ice-cliff. t h e lateral parts of the front are based o n land. t h e bedrock topography is known from a ground-based radio-echo soundings survey in 1089 (glazovskij e t al. 1991). more than 75% of the glacier bed lies below sea level. t h e bed area below sea level extends as far as 12 km u p the glacier from the ice-cliff. t h e glacier thickness increases gradually from the lower part of the ablation zone (150-200 m) towards the middle part of t h e glacier, where it is about 300 m thick. t h e maximum ice thickness is about 400 m . three over-deepened rock basins with a depth of more than 100 m below sea level are distinguishable in the longitudinal profile (fig. 5). they a r e sep ice temperature measurements t h e first direct measurements of the ice tem perature of hansbreen were performed in 1979 by grzes (1980) in a hole located in the lower western lateral part of t h e glacier about 100 m a.s.1. (site g in fig. 2). resistant thermometers were used, but the reliability of the technique was not discussed by the author. however, wheat stone bridge measurements of electrical resistivity suggest that a high level of accuracy might have been achieved using this method. the results demonstrated the occurrence of temperate ice in the profile, except in the thin upper layer of seasonal temperature changes (fig. 3a). t w o d e e p holes were drilled using a 50 mm diameter thermo-electric “hot point” drill in the autumn of 1988. t h e holes were located near the glacier front, in t h e zone of superimposed ice near t h e equilibrium line (jania & pulina 1990). the thermal structure of hansbreen, a tidewater glacier in southern spitsbergen, svalbard 55 basin boundary (the dashed line indicates the assumed ice divide) mountain slopes i 3 conlour lines at every 100 rn a .s.l. la ,. . d . ml i, ??. moraines .. . drilling sites with implanted slrings of lhermistors * frontal ice-cliff in-l 1 iortisuiid fig. 2 . sketch map of hansbreen basin with location of drilling sites. * = data from sites a-g b-f are shown in tables 1-4 and described i n the tcxt. at sites a and d respectively (fig. 2). a mixture of polyethylene glycol with water was applied as an antifreeze during the drilling. platinium thermistors pt 100 with triple wire connections were used. the resistance was measured by an ohmmeter of 0.1% accuracy. this corresponds to a temperature error of l0.26"k. however, when the calibration errors and differences between resistance of wires in the cables are included, the absolute error is probably about r0.4"k. the thermal structure near the front obtained from this method was similar to results obtained by grzes (1980), with temperate ice being rec orded (fig. 3b). the string of thermistors reached a depth of 250 m in site d (fig. 2), where the total glacier thickness is about 330 m. the results of measurements from 1988/1989 are summarised i n table 1. due to severe weather conditions at the time of mounting a data-logger and possible interactions between anti-freeze liquid, ice and cables or the insulation of the thermistors, the accuracy of measurements is probably not wholly consistent. cold ice was found down t o a depth of 60-100 m (fig. 3c). the thermistor at a depth of 250m indicated ice at the pressure melting point temperature. a new system of more precise ice temperature measurements was then developed. pt 100 thermistors with quadruple connections were used. this new survey was based on the quasi compensation method for measuring the resist ance of a platinium thermistor. the principle of measurement is the same as in the compensation method, but the compensator was replaced by a high-input resistance millivoltmeter (10 mq). the temperature measurements were calculated 56 j . jania, d. mochnacki & b . gpdek a siteg tempemlure ('c) -4 -3 -2 -1 0 -r 24%. 79 0 10 20 h 5 r i b sitea temperalure ('c) 3 -2 -1 0 e y c site d temperature ( %) -10 -8 4 -4 -2 0 "s, fig. 3. thermal profiles of hansbreen based upon the preliminary temperature measurements: a , at site g in 1979 (grzes 1980); b, at site a in 1988/1989; c, at site d in 1988/1989 (jania & pulina 1990). for location see fig. 2. table 1. results of temperature measurements at sites a and d in 1988 and 1989 (absolute error ?0.4"c) (a) site a (drilling on 15 august 1988). temperatures in degrees centigrade. ~ date depth 0.5 m 1 0 m 2 0 m 60m 27 aug. 1988 -1.3 -1.5 0.0 -0.4 25 sept. 1988 -2.4 -1.5 0.0 -0.7 (b) site d (drilling on 25 september 1988). temperatures in degrees centigrade. ~ depth date (hour) 0.1 m l m 5 m 1 0 m 1 5 m 20m 6 0 m 100 m 250 m ~~ ~ ~ ~~~ 17 oct. 1988 2 april 1989 i april 1989 (22.30) -7.5 4 . 7 -3.0 4 . 7 -3.0 0 . 5 -1.2 -0.4 (21.50) -10.3 -9.9 4 . 6 -3.9 -3.9 -0.6 -0.8 -0.7 -0.2 (19.00) -9.8 -9.5 -6.7 -4.0 -3.9 -0.6 -0.9 -0.6 -0.2 indicates lack of data the thermal structure of hansbreen, a tidewater glacier in southern spitsbergen, sualbard 57 table 2. results of temperature measurements in shallow holes at sites b , c and e in the period of 1992-1994 (absolute error -+ 0.03"c). (a) site b (drilling on 30 september 1991). temperature in degrees centigrade. date 5 m depth 10 m 15 rn 20 m 5 oct. 1991 16 oct. 1991 8 feb. 1992 1 march 1992 20 march 1992 31 march 1992 20 april 1992 5 sept. 1993* 7 nov. 1993** 4 june 1994** -1.90 -1.89 -2.97 -3.21 -3.10 -3.42 -3.49 -0.27 -8.56 -6.92 -2.24 -2.24 -2.00 -2.05 -2.16 -2.23 -2.34 -1.21 -2.93 -4.59 ~ -1.74 -1.42 -1.60 -1.63 -1.66 -1.68 -1.76 -1.23 -1.25 -1.15 -1.15 -1.15 -1.18 -1.20 -0.63 -2.48 -0.37 (b) site c (drilling on 24 september 1991). temperature in degrees centigrade date 5 m depth 10 m 15 m 20 m 14 oct. 1991 9 jan. 1992 8 feb. 1992 1 march 1992 20 march 1992 31 march 1992 20 april 1992 27 april 1992 5 sept. 1992 17 sept. 1992 7 nov. 1993 28 may 1994 1 oct. 1994 -2.35 -2.19 -3.00 -3.25 -3.46 -3.56 -3.59 -3.74 -3.24 -2.73 -2.59 -6.49 -2.72 -2.91 -2.63 -2.63 -2.63 -2.65 -2.68 -2.70 -2.13 -3.53 -2.96 -3.30 -4.08 -3.95 -2.5*** -2.44 -2.42 -2.42 -2.39 -2.39 -2.37 -2.37 -2.62 -2.41 -2.15 -2.88 -3.11 -1.90 -1.98 -1.98 -2.00 -2.00 -2.00 -2.00 -2.0 -2.13 -2.03 -2.16 -2.26 -2.33 (c) site e (drilling on 1 october 1991). temperature in degrees centigrade. depth date 5 m 10 m 15 m 20 m sept. 1993 -0.05' * * -0.12*** 0.0"' * after opening of new crevasses close to the measurement profile. * * during and after very cold winter with very thin snow cover. **' wider error bar (*o.l"c). -lack of data. from the ratio of voltage drops in the thermistor and the standard resistor. the application of only one millivoltmeter eliminated any instrument error. the thermoelectricity voltage error was eliminated by changing the battery polarity. the resolution of the millivoltmeter and the accuracy of the standard resistor is 0.01%. the absolute temperature error of this method is not greater than +0.03"k. using this method, temperatures were measured in 1991 and 1992 in two 20 m deep holes and, in 1993, in three holes, sites b, c and e respectively (fig. 2). data from these locations are presented in table 2. due to tension flow in the terminal part of the glacier, new wide crevasses were opened on both sides close to the thermistor profile at site b beween the end of 58 j . jania, d . mochnacki & b. gpdek tubk 3 . results of temperature measurements in deep holes at sites b, d and f in 1994 (absolute error ?0.02”c) (a) site b2 128 m a.s.1. (drilling on 13 may 1994). temperature in degrees centigrade. depth date 22 may 1994 4 june 1994 29 sept. 19y4 10 m 25 m 40 m 55 m 70 m 176 m 206 m -2.89 -0.10 -0.05 -0.07 -0.07 -0.16 -0.33 -2.93 4 . 1 7 -0.06 -0.08 -0.09 -0.15 -0.35 -2.17 -0.41 -0.07 -0.07 -0.09 -0.15 -0.26 (b) sitc d2 324 m a.s.1. (drilling on 21 april 1994). temperature in degrees centigrade depth 3 may 1994 date 17 may 1994 4 june 1994 5 oct. 1994 10 m 25 m 40 m 55 m 70 m 85 m 100 m 115 m 130 m 145 m 160 m 175 m 190 m 205 m 220 m 235 m 250 m 260 m 270 m 280 in 290 m 300 m 310 ni 320 m 330 m -3.93 -2.43 -1.55 -0.89 -0.09 -0.06 -0.06 -0.08 -0.08 -0.09 -0.09 -0.12 -0.12 -0.13 -0.14 -0.15 -0.16 -0.17 -0.18 -0.19 -0.19 -0.21 -0.22 -0.22 -0.21 -4.07 -2.44 -1.55 -0.91 -0.32 -0.08 -0.07 -0.09 -0.09 -0.10 -0.11 -0.14 -0.14 -0.15 -0.15 -0.16 -0.18 -0.18 -0.19 -0.19 -0.20 -0.22 -0.22 -0.23 -0.23 -3.31 -2.53 -1.58 -0.91 -0.44 -0.09 -0.08 -0.09 -0.09 -0.10 -0.14 -0.15 -0.15 -0.16 -0.17 -0.19 -0.19 -0.19 4 . 2 1 -0.22 -0.23 -0.23 -0.24 -0.12 -0.21 -3.15 -2.55 1 5 8 -0.90 -0.46 -0.21 -0.09 -0.09 -0.10 -0.11 -0.12 -0.15 -0.15 -0.15 -0.16 -0.18 -0.20 -0.21 -0.22 -0.22 -0.22 -0.24 -0.24 -0.25 -0.25 (c) site f a 0 5 m a.s.1. (drilling on 4 may 1y94). temperature in degrees centigradc depth 5 m 10 m 25 m 40 m 50 m 55 m 70 m 80 m 110 m date 17 may 1994 22 may 1994 -0.44 -0.55 -0.03 -0.03 -0.02 -0.02 -0.03 -0.03 -0.03 -0.04 -0.06 -0.09 -0.07 -0.06 -0.05 -0.05 -0.09 -0.09 5 oct. 1994 4 . 0 1 -0.01 -0.02 -0.04 -0.04 -0.04 -0.05 -0.06 4 . 0 9 the thermal structure of hansbreen, a tidewater glacier in southern spitsbergen, sualbard 59 table 3 (continued) (c) site f 4 0 5 m a.s.1. (drilling on 4 may 1994). temperature in degrees ccntigrade (continued). date 17 m d y depth 1994 22 may 1994 5 oct. 1994 ___ 140 m 170 m 200 m 230 rn 260 rn 290 m -0.09 -0.13 -0.1s -0.15 -0.17 -0.19 -0.10 -0.13 -0.14 -0.1s -0.17 -0.18 -0.10 -0.12 -0.17 -0.19 -0.21 -0.22 april 1992 and september 1993. this is what probably caused t h e failure of the thermistor at a depth of 15 m. the crevasses also caused signifi cant disturbance of temperatures, warming after the summer of 1993 and cooling during and after the cold and dry winter of 1993/1994. a similar cooling during the same winter was noted at site c (table 2 ) . three new deep holes were drilled using hot water equipment for the implanting of thermistors in the spring of 1994. two were located close to the previous temperature profiles (ca. 100 m to the n ) at sites b and d (fig. 2 ) (hence, b2 and d2). ceramic ntc uub31j1 thermistors with double wire connections were applied. this thermistor is about 4% ok-' sensitive, i.e. ten times more than the pt 100 thermistor. because of the greater sensitivity of this thermistor and its resistance (which is considerably higher than that of the cable), only a four-and-a-half-digit ohm meter was used. additionally, in each string of thermistors, one precision-reference resistor was included. this permitted a correction for the changes in cable resistance and thus eliminated the ohmmeter error. this method ensures an accuracy of temperature better than i0.02"c and a of resolution is ~ 0 . 0 1 " c . data are presented in table 3 and fig. 4. the latest measurements of hansbreen temperatures come from a polish swiss project on the energy balance and the origin of the polythermal structure of the glaciers. discussion hydrothermal conditions although measurements were made in different years with different accuracies, the results are not contradictory. between 1991 and 1994, measure ments were made with accuracy greater than five hundredth of a degree. the distinction between temperate and cold ice in the profiles may thus be defined to a high degree of accuracy. the problem of the nature of the boundary between cold and temperate ice is very important for the elucidation of many features of the glaciers of svalbard. part of the problem is defining what is meant by temperate glacier ice (paterson 1981). due to the presence of impurities within ice (e.g. salts, gases, dust), the real (observed) pressure melting point temperature is lower than the pure liquid equlibrium temperature. harrison (1975) studied the problem on blue glacier in wash ington, usa, and recorded temperatures as pre cisely as ~0.00s"c. h e found that, except close to the surface, temperature varies linearly with depth, and the ice is about 0.02"c colder near the surface and 0.04"c colder at 192 m depth when compared with the simplest model (pure liquid phase equilibrium). a general agreement exists between harrison's results and the gradients measured in the temperate layers of hansbreen ice (fig. 4). the exceptions are the temperatures recorded near the glacier bed in the frontal part of the tongue at sites a and b2 (figs. 3b and 4a). both boreholes reached the bed near or below sea level. the lower temperatures found there might be related to the presence of sub-sea permafrost which probably extends underneath the frontal part of the glacier. however. the fine grained, probably marine, sediments found at the bottom of the holes provide a more convincing explanation for the slightly lower temperatures. the invasion of these sediments, with significant saline content, into the lowermost part of both boreholes in the neighbourhood of the ther mistors might have caused contamination. 60 1. j a n i a , d . m o c h n a c k i & b . ggdek a site02 b site 02 temperalure ( 'c) -0.4 -0.3 -0.2 -0.1 0 n o temperalure ("c) -0.5 -0.4 -0.3 -0.2 -0.1 0 0 100 h e r a v f3 2 0 0 c sitcf temperature ( 'c) -0.2 -0.1 0 100 h v e 5 a 8 2 0 0 fig. 4. thermal profiles of hansbreen from measurements in 1994: a , in the frontal part near site b (at b2); 9, near the equilibrium line altitude, 100 m north from the site d (at d2); c , at the site f in accumulation zone (see fig. 2 for location). error bars are indicated. the linear gradient of temperatutes within the temperate ice of blue glacier, washington, u.s.a. (from harrison 1975) is added for comparison. broken lines indicate the extrapolation or interpolation of data. the temperature scale is expanded and differs from that of fig. 3. additional salt and mineral particles are probably responsible for the unexpected cooling of the near-floor part of the profiles. clearly, the prob lem of position of the permafrost limit requires further study. some differences were found between the linear gradient obtained by harrison and down hole measurements at site f (fig. 4c), for example the presence of warmer firn and ice to a depth of about 200 m. this could have been an effect of the percolation of meltwater during the ablation period, on the one hand, and a significant demineralisation of the firn layers on the other. the winter snow cover in the accumulation zones of glaciers in wedel jarlsberg land contains a relatively high amount of salts from sea spray in the air (summary content for the whole snow cover thickness is 24 g m-2 as an average in amundsenisen, at 720 m a.s.1. in southern spits bergen). recent studies of this phenomenon (1989/199(r1993/1994> show that the majority of salts are flushed out from the snow cover and upper firn by percolating meltwater during sum mer (the average salt content in the one-year-old firn is 1.1 g m-*, or less than 5% of the original content). the net accumulation is about 50% of the winter accumulation (gkowacki and pulina, pers. commun.). this implies that much of the meltwater migrates down t o the firn, particularly where slopes are low in glacial accumulation zones. near site f on hansbreen, the summer melting is about 0.7 m (w.e.), which constitutes about half of the total accumulation. no data are available on the salt content in the deeper firn layers and the glacier ice of hansbreen. however, the thermal profile from site f suggests a low salt content down to the 200 m level. analysis of the relations between snow/fir/ice chemistry and firdice temperatures needs data from parallel observations in the same site. in studies of the the thermal structure of hansbreen, a tidewater glacier in southern spitsbergen, svalbard 61 thermal structure of the svalbard glaciers, such processes and phenomena should not be ignored. the relatively clear delineation of the cold temperate ice transition surface is the most impor tant result of the comparison of harrison's studies with the hansbreen data. the depth of this boundary is self-evident in fig. 4. for the first time in studies of svalbard glaciers, the interface between cold and temperate ice has been deter mined directly to an accuracy of +-3 m in depth. in the equilibrium line altitude zone (site d), the thickness of the cold ice is about 95 m and, in the lower ablation zone (site b ) , about 45 m (fig. 4). the results confirm the previous temperature measurements down to 20 m depth, where nega tive temperatures were noted (table 2). by con trast, in the lateral part of the terminus (site g ) , the less precise measurements of grzes (1980) suggest the occurrence of only temperate ice (fig. 3a). o u r first drilling in 1988 (site a in the crevasse zone near terminus) discovered tem perate ice at the 20 m level. however, bearing in mind the low measurement accuracy (.0.4"k), the temperature could have been slightly colder than the pressure melting point, as was the case at site b2 at the 25 m level (fig. 4a). existing data seem to show that the western lateral stream of the glacier may be entirely temperate. if the ice is really cold at this location, its temperature is below the pressure melting point by only about 0.4"c. in the middle of the ablation zone (site c), cold ice exists at the 20 m level, which suggests a continuous cold ice layer between the equilibrium line altitude and the glacier terminus. in the accumulation zone (site f) only tem perate firn and ice were found. at site e, at the 20 m level, the pressure melting point tem perature was measured one year after the instal lation of thermistors. the depth of the cold-temperate transition sur face was compared with the results of low fre quency radio-echo soundings studies in spring 1989 along a long profile. the low frequency recorded indicates thinning of the upper cold ice layer from the equilibrium line altitude to the glacier terminus (fig. 5). the average thickness m a.s.1. 0 5 10 15 h pmbpmeculmdthepr~reme(lingisotherm (precise dep(h a1 sites b and 0) bedrock (broken lines indicale exirapolation) surfaceprotibin 1989 (broken lines indicate edrapolation) localion d temperalure measuremen( sites borehdes wilh themislor internal r d a c t i s recorded by iow frequency n d d soundings fig. 5 . longitudinal section of hansbreen along the centre-line based upon geodetic surveys and ground low frequency radio-echo soundings in 1989 (glazovskij et al. 1991; jania & pulina 1990). points of survcy and soundings are indicated. 62 j. .luniu, d . mochnacki & b . g p d e k of the cold ice is less than 1/3 that of the total glacier thickness. one might expect a complex distribution pattern in the thickness of the cold layer, such as described for storglaciaren, sweden (holmlund & erikson 1989). above the equi librium line altitude, the cold layer seems to decline sharply over a distance of less than 1.5 km between sites d and e (fig. 5 ) . one possible explanation for this phenomenon might be associ ated with the precise location of site d. the drilling profile did not lie exactly on the centre line, but was located slightly to the east, to avoid the crevassed area on the centre-line. thus, site d may represent in part the thermal character of ice originating from the more easterly lower part of the accumulation zone where there is a prevalance of superimposed ice. abrupt changes in cold-layer thickness over a short distance were also observed by radio-echo soundings on other glaciers in svalbard (hagen 1992; bjornsson et. al. 1996). our studies have revealed the main features of the thermal structure of hansbreen (fig. 5 ) . temperate ice dominates in the accumulation area of the glacier. near the equilibrium line, a layer of cold ice overlies thick temperate ice. the cold ice layer continues but becomes thinner near the glacier terminus. below the layer of seasonal changes (20-25 m), temperatures are negative but significantly different: ca. -2.5"c (25 m) near the equilibrium line altitude, ca. -2.0"c (20 m) in the middle of the ablation area, to about -1.2"c (20 rn) and -0.4"c (25 m) in the lower reaches. the temperature of cold ice therefore increases sig nificantly down the glacier. this increase is also obvious at the 10 m level (table 4). hence, the cold layer becomes negative in temperature down the glacier both at the 10 m and 20 m (25 m) levels. table 4. ice temperatures of the iianabreen at the 10 m depth the temperature gradient across the pressure melting isotherm (cold-temperate transition sur face) is very low and varies between only 0.008"c m-' and 0.024"c m-l. it is nearly one order of magnitude weaker than assumed earlier by some authors (e.g. 0.1"c m-', bamber 1987). thermal structure and rudur horizons the interface between cold and temperate ice occurs above the uppermost internal reflecting horizons (irh) recorded during ground-based low frequency radio-echo sounding in april 1989 (glazovskij et al. 1991) and airborne ultra high frequency (uhf) radio-echo soundings in july 1979 (maeeret & zuravlev 1985). the difference is clearly visible at the sites of direct temperature measurements, about 40 m at site b and about 20 m at site d. both values are significantly higher than any error of both radio-echo soundings. in the accumulation area, irhs were registered by low frequency radar at the end of the winter. the uppermost irh is not identical with the cold temperature transition surface. this result con firms bamber's (1987) conclusion about the origin of the irhs in glaciers and does not contradict the results of maeeret et al. (1993) which described a three-layer model. changes in the depth of the irh were noted during the airborne uhf radio echo soundings of the neighbouring weren skioldbreen between july 1979 and september 1984 (maeeret et al. 1993). seasonal fluctuations of the piezometric head within the glaciers of svalbard are well known. water level changes have been observed during speleological explo rations of moulins in hansbreen. in the area of site c, water level increases of about 20 m and o f more than 30 m two kilometres upglacier were noted during the winter september/october site altitude (m a.s.1.) temperatures at 10 m depth date site f site d (ela) site c site b site a 405 324 225 127 ca. 60 0.0-c 22 may-5 oct. 1994 -3.5"c 17 may-5 oct. 1994 -2.7"c 9 jan.-l7 sept. 1992 -2.2"c i march-20 apr. 1992 29 sept. 1994 -1.s"c 25 sept. 1988 the thermal structure of hansbreen, a tidewater glacier in southern spitsbergen, svalbard 63 fig. 6. a concept of the four layer model of hydro-thermal structure of hansbreen. g/ac/qf surlace i cold ice layer i \ me/l/n(r /sofhqitti \ i / \ / i \ i i temperr conlenl / \ / \ i \ -+ \ . i . \ ’ ye&’ ,y 7 . . . . . . ate ice wilh low ’ water . * y,’ 1. s ; 2 . \i i l l temperate ice saluraled by water (4-5 %) . . * . . . . . . . . . _ _ \ / \ i / \ i / \ i / \ i / \ iv bollom layer oflemperale ice wilh lower water content ’ ‘ b e d r o c k / \ i 1991-may 1992 (j. schroeder pers. commun.). unfortunately, the data are barely sufficient for a precise interpretation. however, the increasing distance between the melting isotherm level and the uhf i r h down the glacier profile suggest a similarity with the hydraulic grade line (bamber 1987) as affected by an active outflow from a r channel at the glacier bed. winter storage of water within the glacier continues until a more efficient basal drainage system develops sometime in the first half of the ablation season. the drain age system is fed by large quantities of meltwater in the first weeks of summer. before the opening of the drainage channel system, water pressure rises and the piezometric head may reach the cold-temperate transition surface. cold ice may be regarded as an impermeable layer (moulins are exceptions). thus, the pressure of stored water may exceed overburden pressure. geyser like water spouts on the surface of weren skioldbreen have been noted in the ablation zone and even in the accumulation area (baranowski 1973; glowicki 1982). the importance of the cold ice layer in the elucidation of the hydrology of glaciers is thus evident and confirms that there are significant fluctuations in the water levels in subpolar glaciers. the interpretation of the radio-echo sounding data (maeeret & zuravlev 1985; bamber 1987; maeeret et al. 1993), together with the results of our temperature measurements, enable us to propose a model for the hydrothermal structure of the glacier which consists of four layers in the ablation zone (fig. 6). the uppermost layer of ice (i) is cold and “dry”. below the cold-temperate transition surface, there is temperate ice with a seasonally-fluctuating bulk water content (ii), (usually the ice is nearly “dry”). the first irh forms the lower boundary of this layer. tem perate ice (111) with an anomalously high water content ( 4 5 % ) has been detected below the irh by maeeret et al. (1993). the layer is more than 60 m thick (up to 220 m). temperate ice with a smaller content of water (iv) is placed by the authors between the bedrock and layer 111. intriguingly, layer i11 is oversaturated with water. possibly this is due the presence of water inclusions in the form of micro-channels within the ice (raymond &harrison 1975). indeed, such channels and fissures (diameter 4-8 mm) were found in a few levels of the ice-core from the amundsenisen (zagorodnov & zotikov 1981). they contained highly mineralised water (pulina 1986). sea-spray salts deposited in the snow cover may be identified as a source of such higher min eralisation of water inclusions significantly deeper within the ice than the lower limit of firn. the seasonal fluctuations in depth of the irh (i.e. the water saturated layer) at werenskioldbreen suggest that layer i1 may have a similar structure. 64 j . jania, d . mochnacki & b . ggdek alternatively, the fluctuations occur only within layer 111, whereas layer i1 is temperate and nearly impermeable because of the lack of micro channels. the problem needs additional study. however, we agree with maeeret et al. (1993) that a multi-layer hydrothermal structure seems to be typical for many of the larger svalbard glaciers. shallow ice temperatures the data presented in the tables (tables 1, 2 and 3) show, as expected, seasonal temperature changes within the activ; layer. the ice tem perature at the standard 10 m depth (tlo) is widely used for comparison of the thermal status of gla ciers (paterson 1981; blatter 1987), including the glaciers in svalbard (maeeret & zuravlev 1985; bamber 1978). seasonal temperature fluctuations are easily demonstrable at this depth except in the accumulation zone. the winter “cold wave” can also be recognised at a deeper levels (15 m, even 20 m) but with a significant time delay (ca. 0.5 yr) and amplitudes of the order of 0.2”c. nevertheless, averaged 10 m temperatures seem to be quite representative of particular parts of the glaciers. data from other svalbard glaciers have been compiled for comparison with hansbreen. the most detailed set of data relates to temperatures at the 10 m level (table 5; cf fig.1 for location). these temperatures have been compared with the mean annual air temperatures at the neighbouring meteorological stations. table 5 also displays cal culated air temperatures at the altitudes of points of the ice temperature measurements (an adia batic lapse rate of 0.6”c per 100 m was used). air temperatures might be lower by 1-2°c due to the influence of the local climate of glaciers (koryakin et al. 1985). in all cases, tlo is significantly higher than the assumed air temperatures. this confirms the importance of heat transfer by the percolation of water (release of latent heat of fusion) within glacier accumulation zones. the phenomenon indirectly influences entire glaciers due to the advection of temperate ice to ablation zones. penetration of short wave radiation to some depth in blue ice in the ablation zone also influences the shallow ice temperatures. earlier studies deter mined the relations between the annual mean air temperatures, mass balance facies and the tlo in polar and subpolar conditions (hooke et al. 1983; blatter 1987). in such conditions, differences between the mean annual ice and air temperatures were observed, with the ice tending to be warmer than air. with respect to svalbard glaciers, an important statistical relationship between tlo and the mean annual temperatures in the equilibrium line altitude zone (correlation coefficient r = +0.87), and an even stronger relationship in ablation areas (r = +0.97), has been established. the statistical probability of other results are 1% and 0.1% respectively. this suggests that the 10 m-level ice temperatures are in or near equilibrium with the contemporary climatic conditions. the tlo temperatures of hansbreen are highest among the data referring to the ablation area. the location of the glacier in the southwest part of the archipelago, where the influence of oceanic air masses (e.g. higher accumulation) is stronger, seems to be a reason for this. the accumulation areas of svalbard glaciers are usually temperate or near temperate. the hansbreen accumulation zone temperatures are typical for areas strongly affected by meltwater percolation and associated refreezing effects. conclusions the polythermal structure of hansbreen is similar to many larger svalbard glaciers; it is of subpolar type. the upper, cold layer of ice is thinner and warmer by comparison with the other glaciers. the cold ice layer seems to be in a state of evolution (reduction of thickness and increase of temperature) as a reaction to climatic change. the areal pattern of the cold ice layer (its presence and thickness) appears to be more com plex than that proposed by more traditional models (e.g. schytt 1964). cold ice did not exist in the western lateral part of the glacier due to the proximity of “warm” tributary accumulation zone and the high ablation near to the terminus. fluctuations in the depth of the irh suggest the possibility of water level changes within the temperate ice which underlies the cold ice layer. a four-layer hydrothermal model of glacier ther mal structure with depth seems to be adequate for the interpretation of the results of temperature measurements, radio-echo sounding data on irhs and direct hydrological observations. the model is provisional and requires further sim ultaneous studies both of ice temperatures and of the radar reflection horizons. t h e thermal structure of hansbreen, a tidewater glacier in southern spitsbergen, sualbard 65 ra6le 5. tempcratures of ice at the 10 m (tlo) svalbard glaciers (degree centigradcs). atlitude tio meterol. air air t” gi acie r (ma.s.1.) date (ice) station t* period (glacier) ( 1 ) vcstfonna (2) (3) (4) hoghetta holtedahl fonna kongsvegen ( 5 ) bertilbreen (6) lomonosovfonna (7) nordenskioldbreen (9 ) fridtjovbreen (10) amundseniscn (11) hansbreen 312 550 622 1200 firdice 370 630 475 325 1050 670 590 600 400 700 320 224 128 15.07.58 5.08.5x 11&22.04.1958 20.05 .58 26.06.58 27.07-3.08.58 4.06.87 may 1980 27.06.65 16.08.65 4.06.65 16.6.65 may 1980 july 1981 212.04.1989 5.10.94 14.10.91 16.10.91 -8.5 -1.43 -0.86 -1.43 -8.0 -11.0 -1.6 -4.75 ca. 0 -4.75 -4.25 -2.67 -2.33 -5.0 -4.33 -7.5 -3.0 -0.56 -3.9 -3.15 -2.91 -2.22 murchinson fjorden pyramiden nyalesund ny-hesund pyramiden pyramiden pyramiden longyearbyen lufthavn isfiord radio hornsund hornsund -8.6 1957-58 -7.1 1979-81 -6.0 1979-83 -6.0 1979-83 -5.4 193g-56 -7.1 1979-81 -5.4 1930-56 -5.4 193&56 -6.2 1965-74 -6.8 1979-83 -5.2 1965-74 -4.9 1951-70 -4.9 1979-93 -4.9 1979-93 -10.4 -11.9 -12.2 -8.5 -8.5 -8.1 -9.5 -9.2 -8.3 -11.0 -9.3 -8.7 -10.0 -10.4 -1.5 -7.2 -9 1 -6.7 -6.1 -5.5 notes: alt.. altitude; ti”, temperature of ice at the 10 m depth; t*, mean annual air temperature at the nearest meteorological station; t i *, calculated mean annual air temperature above place of ice tempcrature measurements (adiabatic cooling assumed as 0.6”~/10nm). acknowledgemenfs. the authors are grateful to h . blatter and j . 0. hagen for criticism and valuable suggestions to a draft version of the paper, to two anonymous referees for constructive comments for improving the paper, and l o “geo style” ( i . morawiecka and p. t. walsh) for improving the language. thanks also to p. glowacki, j . kida and j. trynda for participation and assistance in the field activity. this research was supported by the committee on scientific the institute of geography, eth-zurich (h. blatter and a. ohmura) made possible the advanced studies of the hansbreen structure in 1994. cooperation with the institute of geophysics, polish academy of sciences and the logistic support of the polish polar station, hornsund, is greatly appreciated. research, poland (kbn) under the terms of research grant no. 6-6257-91-02 for the project on “changes of mass balance. references geometry and t h e m a i regime of svalbaid glaciers under the influence of contemporary climatic warming”. cooperation with ahlmann, h. w . 1935: contribution to the physics of glaciers. geogr. j . 86f2), 97-113. 66 j . jania, d . mochnacki & b . gpdek bamber, j. l. 1987: internal reflecting horizons in spitsbergen glaciers. ann. glaciol. 9, 5-10, baranowski, s . 1973: geyser-like water spouts at werens kioldbreen, spitsbergen. i a s h publ. 95, 131-133. baranowski, s. 1977: the subpolar glaciers of spitsbergen seen against the climate of this region. acta univer. wratisl. 410. bj0rnsson, h., gjessing, y., hagen, j . o., hamran, s. e . , liest01, o., pblsson, f. & erlingsson, b . 1996: the thermal regime of subpolar glaciers mapped by multi-frequency radio echo sounding. j . glaciol. 42, 23-32. blatter, h . 1987: on thermal regime of an arctic valley glacier: a study of white glacier, axel heiberg island, n.w.t., canada. j . glaciol. 33(114), 200-211. blatter, h. 1990: effect of climate on the cryosphere. climatic conditions and the polythermal structure of glaciers. federal institute of technology, 190 zurich. 101 pp. dowdeswell, j . a , , drewry, d. j . , liest01, 0, & orheim, 0. 1984: radio-echo sounding of spitsbergen glaciers: problems in the interpretation of layer and bottom returns. 1. glaciol. 30(104), 16-21. fowler,a.c.&i.arson,d.a. 1978:ontheflowofpolythermal glaciers: i. model and preliminary analysis. proc. r. soc. lon. ser. a , 363 (1713). 217-242. glazovskij, a . f.;kolondra, l., moskalevskij, m. yu. & janija. ja. 1991: issledovanija prilivnogo lednika chansa na spicsbergene (studies of the tide-water glacier hansbreen on spitsbergen-summary), materialy gljaciologiteskich issle dovanij 71, 145149. giowicki, b. 1982: some hydrological phenomena observed in the outflow from the werenskiold glacier basin. acra uniuersiratis wratislaviemis nr 525, 4%56. grzes m . 1980: non-cored hot point drills o n hans glacier (spitsbergen), method and first results. pol. polar res. z(2 3 ) . 75-85. hagen, j.o. 1992: temperature distribution in broggerbreen, lovcnbreen and kongsvegen, north-west spitsbergen (abstract). in: field workshop on glaciological research in svalbard. current problems, polish polar station, hornsund, 2 6 3 0 april 1992. p. iv-5. harrison, w. d. 1975: temperature measurements in a tem perate glacier. j. glaciol. 14(70). 23-30. holmlund, p. & eriksson, m. 1989: the cold surface layer on storglaciaren. geogr. ann. 71a (3-4). 241-244. hooke, r. l e b., gould, j. e. & brzozowski, j. 1983: near 94 pp. surface temperatures near and below the equilibrium line on polar and subpolar glaciers. zeitschr. gletsch. glazialgeol. 19 ( i ) , 1-25. jania j . 1988: dynamrczne procesy glacjalne nu pohdniowym spitsbergenie w swietle badari fotointerpretacyjnych i fofogrametrycznych (dynamic glacial processes in south spitsbergen i n the light of photointerpretation and photo grammetric research-summary), uniwersytet slaski, katowice. 258 pp. jania, j. & kolondra, l., 1982: field investigations performed during the glaciological spitsbergen expedition in 1980. interim report. uniwersytet haski, katowice. 32 pp. jania, j. & pulina m . 1990: field investigations performed during the glaciological spitsbergen expedition in summer of 1989. interim report. uniwersytet slaski, katowice. 13 pp. korjakin, v . s., krenke, a. n. & tareeva, a. m. 1985: raseetnaja akkumulacija na vysote granitsy pitanja lednikov (estimated accumulation at the equilibrium line altitude). pp. 54-61 in kotljakov, v.m. (ed.): gljaciologija spicbergeria (glaciology of spitsbergen). “nauka”, moskva. maeeret, ju. ja., moskalevsky, m. yu. & vasilenko, e. v. 1993: velocity of radio waves in glaciers as an indicator of their hydrothermal state, structure and regime. j. glaciol. 39(132), 373-384. maeeret, yu. ya. & zuravlev, a. b . 1985: tolseina, ob’em i stroenie lednikov (thickness, volume and structure of glaciers). pp. 7-35 in kotljakov, v . m. (ed.): gljaciologija spicbergena (glaciology of spitsbergen). “nauka”, moskva. paterson, w. s. b . 1981: the physics of glaciers. pergamon press. oxford. 380 pp. pulina, m. 1986: problematyka geomorfologiczna i hydro glacjologiczna polskich wypraw na spitsbergen w latach 1979 i 1980 (geomorphological and hydro-glaciological inves tigations of the polish spitsbergen expeditions in 1979 and 1980). czasopisrno geograficrne 57 (3), 367-392 (in polish). raymond. c . f. & harrison, w. d. 1975: some observations on the behaviour of the liquid and gas phases in temperate glacier ice. j . glaciol. 12, 19-44. schytt, v. 1964: scientific results of the swedish glaciological expedition t o nordaustlandet, spitsbergen 1957 and 1958. geogr. ann. 46(3), 243-248. zagorodnov. v. s. & zotikov, i. a. 1981: kernovoe burenije na spicbergenene (ice core drilling i n spitsbergen). marerialy gljaciologiteskich issedovanij 40, 157-163. trichinella sp. in polar bears from svalbard, in relation to hide length and age thor larsen and bjbrn kjos-hanssen larsen, t. & kjos-hanssen, b . 1983: trichinella sp. in polar bears from svalbard, in relation to hide length and age. polar research 1 n.s., 89-96. oslo. d i a p h r a g m and masseter muscles from 376 polar bears ((irsur maririmus), 252 ringed seals (phocn hispida), 84 bearded seals (erignarhus barbarus), and 77 arctic foxes (alopex lagopus) from svalbard were examined for trichinelln. infection rates in polar bears varied between 23 and 5 8 % , and between 3 and 67% in arctic fox. none of the seals were infected. trichrnella in polar bears is probably transferred through cannibalism and scavenging upon polar bear carcasses. infection rate in arctic fox was high when they preyed upon polar bear carcasses before polar bear hunting was prohibited in 1973. a low infection rate seems more natural when such prey is not available. n o difference could be found in infection rate between male and female polar bears. there is only a slight increase in infectlon rate with age, as calculatcd from hide lengths, and many adult animals remain uninfectcd. geographlcal isolation of polar bear populations may explain differences in trichinella infection rates between beara from arctic amcrica and arctic europe. possible explanations are that discrete polar bear populations have different food habita. or that they are exposed to different trichinella strains. thor larsen, norsk polarinsriturr, rolfsiangueien 12, 1330 oslo lufrhaun, norway; bjgrn kjos-hanssen. tordenskioldsgt. 4, 4000 stauanger, norway. march 1983 (reuited may 1983). introduction trichinellosis in free-roaming polar bears (ursus maritimus) was first described by parnell (1934). later research has shown that trichinella has a circumpolar distribution and that the parasite has occurred in polar bears for a long period of time (jepsen 1968). bears can be infected by eating other bears or bear carcasses, although some authors have claimed that polar bears receive trichinellosis mainly from eating seals o r walruses (ozeretskovskaya & uspensky 1957; manning 1960; lentfer 1976). the objective of this paper is to discuss probable infection pathways for tri chinella in arctic ecosystems, to evaluate possible differences in trichinella infection rates in rela tion to sex and age of polar bears, to discuss the effect of various trichinella strains on polar bears and other species, and to compare trichinella infections in polar bears from various regions in order to differentiate between populations. material and methods the material consisted of 342 diaphragma and 34 masseter muscle samples from 376 different polar bears collected between about 1950 and 1970, diaphragma samples from 252 ringed seals (phoca hispida) collected in 1981 and 1982, and from 84 bearded seals (erignathus barbatus) from 1954. seventy-seven diaphragma samples from arctic foxes (alopex lagopus) collected between 1954 and 1980 were also studied. the polar bear samples were either dried or preserved in 70% ethyl alchol or in 4% formaldehyde. the seal and fox samples were kept frozen at 20°c below zero. thirty polar bear samples were from animals whose age was determined by sectioning and counting the teeth cementum layers. one hundred and sixty-seven samples were from bears with known hide length. trichinellosis was stud ied by means of the compression method: ca. 4 g muscle tissue was squeezed between glass plates to a thin layer which permitted inspection under a 5 0 ~ enlargement microscope or tri chinoscope, and counting of trichinellas in the sample. dried and alcohol preserved samples were softened in water, and formaldehyde pre served samples were softened and clarified with a 5% koh solution (roth 1949) prior to compression. after such treatment, trichinella capsules could be identified (fig. 4). frozen samples and questionable formaldehyde samples were studied by the digestion technique where the magnet stirrer method was used (framstad 1980). 89 90 t. larsen & b . kjos-hanssen b l l i ltkgtn i h i n fig. 1. percentage of polar bears from svalbard infected b) tri chinella sp. versus hide lengths. age determination and growth curves (figs. 2 and 3) are based on body measurements and tooth cementum age determinations for 82 male and 83 female polar bears captured alive and studied in svalbard between 1967 and 1980. hide lengths were calculated by converting measured zoologi h i? -~ . --~ fig 2 growth curve of female polar bears from svalbard age versus hide lengths (n = 83) cal lengths with a factor of 1.18 for males and 1.23 for females. the correction factors have been calculated from lon0 (1970), who gives zoological lengths and hide lengths for 43 male and 34 female polar bears from svalbard. bears with hides between 130 and 229cm were classified as cubs or juveniles, i.e. bears before they are weaned and leave their mother in their third year of life. bears with hide lengths between 230 and 310 cm are classified as subadults or adults. no further attempt was made to distinguish between age groups because of the amount of overlap in hide lengths. results the results of the trichinella investigations in the total of 376 polar bear samples are given in table 1. table 2 shows the trichinella infection in 30 bears aged by tooth cementum layer counts from ryke yseoyane 1967-69. in table 3, the occur rence of trichinella in polar bears is plotted against hide length of intervals of 10 cm. figures 2 and 3 show female and male growth curves. eighty-six bears had hide lengths less than 230 cm and are classified as cubs and juveniles. of these 28 had trichinellosis, giving an infection rate of 33%. of the remaining 81 bears classified as subadults or adults, 29 had trichinellosis, i.e. an infection rate of 36%. the percentage number of polar bears with trichinellosis versus hide lengths at 10 cm intervals is shown in fig. 1 . the incidence of trichinella infection in different polar bear samples varies between 23 and 58%, with an average of 32.7%. four of the six different sample sets had an infection rate between 23 and 33% (table 1 ) . the infection rate of males was not significantly different from that of females (tables 2 and 3). there was no evident increase in infection rate with increasing hide length (fig. 1). of the 77 arctic fox samples, 10 of a total of 15 from tjuvfjorden in 1954-55 were infected, giving an infection rate of 67%. the remaining 62 fox samples were from northwest spitsbergen in 1979. only 2, or 3%, were infected. none of the 252 ringed seal samples nor 84 bearded seal samples were infected by trichinella. discussion polar bears are typical carnivores, and 90% of their diet consists of seals (l0n0 1970; larsen trichinella in polar bears 91 290 280 270 260 250 2 4 0 230 220 ~ 210 2 0 0 ~ 190 iao ~ 170 ~ 160 150 140 130 table 1. occurrence of trichinella sp. in polar bear diaphragma samples from different localities in svalbard between 1950 and1970. 1 locality no. of year samples no. of positive % inf. sampled by b j ~ r n d y a tjuvfjorden ryke ysebyane hopen hopen halvmlnebya/ tjuvfjorden ca. 1950 12 1954 66 196749 104 1966-67 57 1969-70 40 1969-70 63l 7 32 34 13 10 16 58 zool. mus. oslo 48 0. l0n0 33 k. torsvik 23 hopen crew 25 hopen crew 25 p. johnsen, a . strand and s . ytreland s u d a v e r a g e 342l 112 32.7 1. in addition, 34 masseter muscle samples were studied, of which 6 were infected. 1978). seals, and particularly ringed seals, which are the polar bears' main prey animal, eat mainly plankton, fish or benthic organisms, in which trichinella cannot develop. the absence of tri chinella in the seals in this study is in agreement with the observations of thorshaug & rosted (1956), who did not find trichinellosis in any of 1556 samples from various arctic seal species. madsen (1961) found only one infected ringed seal in 1775 animals from greenland, and fay (1960) only two in 300 from alaska. trichinellosis in seals can be due to an occasional eating of i i remains of an infected polar bear carcass. it has been experimentally confirmed that trichinella can be transferred b y amphipods and esh (fay 1960; ozeretskovskaya et al. 1969). trichinellosis in seals must be regarded as a curiosity and cannot be taken to explain the high infection rate in polar bears, because it is unlikely that crustaceans or fish play any role in the transfer of the parasite in nature. various studies of walrus (odobenus rosmurus) give a trichinella infection rate between 2% (born et al. 1982) and 9% (thorshaug & rosted 1956). the walrus is a bottom feeder which lives mainly from molluscs. there are reports, how ever, about walruses which occasionally eat meat or hunt for seals and other mammals (degerbd table 2 . trichinellosis in 30 polar bears from ryke y s e ~ y a n e , svalbard 1967-69, aged by tooth cementum layer counts. no. of dd no. of 9 9 age examined infected examined lnfected 1 2 2 2 3 1 1 3 1 4 1 4 3 1 1 5 1 1 6 2 1 7 2 1 1 1 8 2 9 1 i 1 1 1 ._ 12 1 120 ' , 7+ age 13 1 1 1 1 2 3 4 5 6 fig. 3. growth curve of male polar bears from svalbard. age sum 14 3 16 5 versus hide lengths (n = 82). 92 t . larsen & b . kjos-hanssen fig. 4 . trrichinello capsules in formaldehyde preserved polar bear diaphragma samples compressed after treatment with a s'7c koh solution (photo h . ulveseter) & freuchen 1935; fay 1960). thus. trichinellosis in walrus can be explained by its occasional eating of polar bear meat or dog meat which is infected. on the other hand, the walrus is not normally a prey animal for polar bears, unless it eats car casses from walrus hunts (kulstad 1970: l m 0 1970). the walrus was very rare in svalbard waters between 1945 and 1970 (larsen & nor derhaug 1974). all walrus hunting in norwegian waters was prohibited in 1952. walruses or walrus carcasses have therefore not been available as an important food resource for polar bears in sval bard when this study was made, and cannot explain trichinella infection rates. arctic foxes are not common prey animals for polar bears. trichinellosis in arctic fox has been described from all parts of the arctic. rausch (1970) esti mated that about 10% are infected; roth (1949) found an infection rate of 3% in greenland. the infection rate in the fox material from svalbard in 1979 is comparable with their findings. in 1954-55 foxes from tjuvfjorden had a compar atively very high trichinella infection rate, which can be explained by their scavenging upon polar bear carcasses. during this period there was an extensive polar bear set gun harvest in that area, trichinella in polar bears 93 table 3. trichinellosis versus hide lengths in polar bears from svalbard hide length 140-149 15b159 160-169 170-179 180-189 190-199 2 w 2 0 9 210-219 220-229 23b239 24cl249 250-259 260-269 2lc-279 280-289 290-299 3 w 3 1 0 no. of dd no. of 99 exam. inf. exam. inf. 0 0 1 1 4 1 1 0 2 0 4 1 2 0 3 0 4 1 1 0 3 1 3 2 6 1 8 8 3 0 21 5 7 3 1 3 4 ~~ no. of dd 99 combined exam. inf. % infected 1 s 6 5 5 6 14 24 20 7 10 15 8 3 9 1 1 14 3 21 9 1 19 3 3 18 i 1 9 3 9 1 1 85 28 82 29 167 57 and trappers abandoned polar bear carcasses after they had skinned the animals. these carcasses must have been an important food supply for arctic fox during the winter, when other food was scarce. the foxes from northwest spitsbergen were collected after six years of total polar bear protection. polar bear carcasses were conse quently not available as fox food. foxes in this region mainly depend upon dead reindeer (ran gifer tarandus platyrhynchus), ringed seal pups, birds, or caches collected during summer. a low infection rate in svalbard foxes is probably natural. the occurrence of trichinella in the arctic is far more common in polar bears than in any other free-roaming species. but the high infection rates cannot be explained by their consumption of seals, nor occasional preying upon walruses or other species. polar bears have a large muscle mass and high longevity. scavenging and possibly also cannibalism (taylor et al. 1983) are normal in this species. the interaction of these factors causes the polar bear to act as an infection res ervoir for trinchinellosis, and maintains the cir culation of the parasite in the ecosystem of which the polar bear is a part. in areas where polar bear hunting is permitted, carcasses left in the field after being skinned will maintain trichinellosis in polar bears in that region. in this study, the infection rate in svalbard bears vanes between 58% found in the material from b j ~ r n 0 y a around 1950, and 23 to 33% in the samples collected between 1966 and 1970 (table 1). material from the 1950s studied by thorshaug & rosted (1956) showed59% infection i n 278 samples from svalbard and greenland polar bears. chi-square tests show significant dif ferences between that study and infection in sval bard samples after 1966 (p < 0.001). when polar bears were protected from hunting in the soviet union in 1956, the annual harvest in the western soviet arctic and adjacent waters was reduced by more than 100 bears (uspensky 1969). this means that relatively fewer bear carcasses were left in the field available for scavenging. this would in turn have reduced the probability of trichinella infection in live bears from svalbard and the western soviet arctic which belong to one com mon population (larsen 1978; larsen et al. 1980), and may explain the difference between the material from the 1950s and later years. significant differences in percentage trichinel losis between polar bears of different sizes, i.e. age, could not be demonstrated in this study. nor 94 t. larsen & b . kjos-hanssen could we find that the number of trichinella lar vaes per g muscle tissue increased with age. some bears are infected before they are weaned and become mature, but many adult bears remain uninfected (table 3, fig. 1). some reservations must be made because of the small sample size, but when samples are pooled in a cub/juvenile and a subadult/adult group, there is still no dif ference between them. because polar bears are typical scavengers and sometimes cannibals, one would expect that the longer a bear lives, the greater the probability of an infection. one pos sible explanation is that infected bears die, so that the relative infection rate remains stable with increasing age. but this would mean that adult bears would be absent from the population. which they are not (t. larsen, unpublished data). such a mechanism would also be a significant mortality factor. because polar bears have a low recruit ment rate and very slow population growth (tay lor 1982), deaths from trichinellosis would be detrimental to t h e population. previous studies have shown that trichinellosis in polar bears where 100 or more animals have been studied, varies between 24 and 64% (roth 1949; thorshaug & rosted 1956; fay 1960; mad sen 1961; lentfer 1976). the low infection rate in svalbard bears between 1966 and 1970 is com parable with the 24 to 26% infection rate found in greenland bears (roth 1950; madsen 1961). chi-square tests could not reveal significant dif ferences (p < 0.05). recoveries of bears marked in svalbard show that some of them migrate to east greenland (larsen 1972). craniometric stud ies have revealed differences between bears from many regions, but not between svalbard and east greenland bears (manning 1971). there is prob ably an exchange of bears between the two areas, which in turn may explain the similarity in tri chineflu infection rates. marwrecapture pro grammes have demonstrated that there are sev eral discrete subpopulations off the north american coasts, with limited exchange between them (lentfer 1972; stirling et al. 1977, 1980; stirling & kiliaan 1980). chi-square tests show significant differences (p < 0.001) in samples of more than 100 specimens between alaska and canada and between alaskdcanada and green land. the differences cannot be found in biases caused by methods used, because all studies referred to used the compression method. fur thermore, the differences are probably not caused by sex and age differences in the material, because trichinellosis in polar bears seems to be indepen dent of sex and relatively independent of age, according to our study. the polar bear hunt in svalbard, greenland and canada, and partly in alaska before 1960, was not selective with regard to sex and age, which would have minimized a sampling bias if it had been. we may therefore observe differences in trichinella infection rates which reflect polar bear population discreteness. polar bears may have developed an active resistance which reduces their risk of being heav ily infected with trichinellas from arctic ecosys tems. during the winter 1950-51, odd lon0 fed four sledge dogs with polar bear meat which was positively infected. a later autopsy of the dogs showed that only one of them had been infected from the polar bear meat (thorshaug & rosted 1956). laboratory mice and man react differently to arctic strains of trichinellu and infections from southern regions. nelson et ul. (1966) and dunn (1978) found that trichinellu from alaska had a lower infectivity in rats and domestic pigs than the european strain of the same parasite. tri chinella from wild polar bears from frans josef land and wrangel island had less infectivity in laboratory mice than laboratory trichinellu strains and strains from southern regions (ozer etskovskaya et al. 1969; pereverzeva et al. 1973). it has been demonstrated that polar bears are more vulnerable to trichinellas from southern regions than they appear to be to strains from their natural environment. between 1946 and 1964, nine polar bears in moscow zoo died from trichinellosis after they had been infected by pest rodents (khutoyanskii & nemov 1969). autopsy of an adult female polar bear which was born in captivity and died in como zoo in minneapolis, showed a mass infection of trichinellu which it must have received from eating infected meat or pest animals in the zoo (m. taylor, pers. comm.). ozeretskovskaya et al. (1969) showed that humans infected with trichinellu on the arctic bennett island showed symptoms after an average 30.5 days, while persons who received trichinel losis in the bryansk and smolensk provinces on the russian mainland, showed symptoms after an average 21.3 and 21.2 days, respectively. the findings above show that trichinella strains which occur in the arctic differ from others with regard to infectivity and other properties. nelson (1970), pawlowski (1981), and steele & schultz (1978) state that many areas of the world have their own peculiar trichinella strains that behave differently trichinella in polar bears 95 nellas with different infectivities. this may explain the differences in infection rates between populations. in their natural foci, and that such strains have different infectivity. recent research has shown that there are at least three different strains of trichinellas in natural ecosystems. the taxonomic classification is still controversial (martinez fer nandez & duran 1981; pawlowski 1981). all three strains are morphologically identical, but have different biological characteristics and do not interbreed (britov & boev 1972; dunn 1978). in this study, we have classified them as species with the nomenclature trichinella spiralis, trichinella natiua, and trichinella nelsoni, according to r.vik (pers. comm.). modern research classifies trichi nella nativa as the aboriginal species which had wild asian carnivores as its hosts (britov & boev 1972; dunn 1978). trichinellaspiralisis a youngerspecies andoriginatedfrom trichinellanatiua when the pig was domesticated in asia 5000-8000 years ago (dunn 1978). from asia it was transported to europe and much later to north america, where trichinellosis until then had been absent. many studies assume that trichinellosis in the arctic is caused by trichinella spiralis, but do not give any further classification (roth 1949; rauschetal. 1956; madsen 1961; thing et al. 1976; born et al. 1982). ozeretskovskaya & uspensky (1957) and dick & chadee (1981) suggest that trichinella in arctic soviet union and in canada are trichinella natiua. in our opinion, trichinella natiua can have entered arctic ecosystems from asia long before humans settled in the arctic. early explorers and other human activities in the last few hundred years may have introduced other trichinella strains to the arctic. thus, different trichinella strains or sibling species may be present in different arctic regions. we can therefore offer three possible expla nations for the significant differences in trichi nella infections found in polar bears from various areas: 1 . the almost exclusive circulation of trichinella in polar bears within geographically isolated areas may encourage parasitehost co-evolution and a greater tolerance by the host towards the parasite, as described by ozeretskovskaya et al. (1969) and dunn (1979). this may explain the polar bear tolerance against infections, and may also explain differences in infectivity between bear popula tions because of differences in evolutionary patterns. 2. subpopulations of polar bears may have been or may be exposed to different strains of trichi 3. differences in polar bear hunting practices and harvest levels may cause differences in the like lihood of live bears being infected through scav enging, which again may explain differences in infection rates between populations. we do not know which of these mechanisms, or whether a combination of them, regulate tri chinellosis in polar bears. however, the sig nificant differences in trichinella infection rates between areas confirm the lack of mass exchange of bears previously demonstrated through mark ing and recapture programmes, satellite telemetry and morphometric studies. if polar bear popu lations were not relatively discrete, migration and exchange of bears would cause more uniformity in infection rates throughout the arctic. quan tification of trichinella rates in polar bears may therefore be another tool with which to discrimi nate between populations. it should only be used, however, when samples are representative and sufficiently large, when preservation and labora tory techniques are comparable, and if sampling is done simultaneously. further studies need to be done on trichinella taxonomy in the arctic, and on the infectivity and biological properties of strains or sibling species occurring in polar bears. acknowledgements. we thank the following persons and institutions for making this study possible: muscle samples for trichinella analyses were collected by ian gjertz, per johnson, christian lydersen, odd l0n0, pal prestrud, arild strand. kristian torsvik, svein ytreland, and by weather station crew on hopen 19664i7 and 1969-70. the material from bjorneya was made available to us by the zoological museum in oslo. lillian meling and sverre trosvik helped with the laboratory work, and halldis lie, dr. ian stirling, dr. mitchell taylor and dr. r . vik offered valuable help and criticism during the writing ofthe manuscript. the work wasfinanced by norsk polarinstitutt. references born, e . w . , clausen, b . & henriksen, s . aa. 1982: trichineffu spiral& in walruses from the thule district, north greenland, and possible routes of transmission. z. saugerfierk. 4 7 ( 4 ) , 246-25 1 . britov, v. a . & boev, s. p . 1972: taxonomic rank of tri chinellae of different strains and character of their circulation. vesmik akademii nauk kuzakchrkoj s s r 2 8 ( 4 ) , 27-32. degerbel, m. & freuchen, p. 1935: mammals. report of the fifth thule expedition 1921-1924. nordisk forlag, copen hagen. 278 pp. 96 t. larsen & b. kjos-hanssen dick, t. a. & belosevic. m. 1978: observations on a trichinella spiralis isolate from a polar bear. 1. parasir. 64(6). 1143 1135. dick. t. a & chadee, k . 1981: biological characterization of some north american isolates of trichinella spiralis in mice pp. 2%33 in kim, c w.. ruitenberg. e . j . & teppema. j . s (eds.). trichinellosis proceedings of rhe fijrh inrernarional conference on trichmellosu, reedbooks ltd. surrey. england dunn. a . m . 1978: vererinorv helminrhology. william hei nemsnn medical books ltd.. london. 323 pp. fay. f. h . 1960: carnivorous walrus and some arctic zoonoses arcric 13. 111-122. fay. f . h. 1967: experimental transmission of trichinella ipir a h via marine amphipods can. 1. zoo/. 46. 597-599. framstad. k 1980: magnetrer-trikinkontrollmetoden. ,vor aerer~ncrridsskrifr 92. 507-5 12. jepsen. aa. 1968: forelesninger over kgdkonrrol. den kgl. veterinzr og landbohejskole. dsr forlag. copenhagen khutoyanskii,a a . & nemov.g. s . 1969:thepolarbearinzoos inthe ussrandothercountries. pp. 142-156inbannikov.a. g . . kishchinski. a. a . & c‘spensky. s. m . (eds.) the polar bear and irs conseriiarion in rhe souier arcnc. gidrometerol ogizdat. leningrad kulstad. j 1970: besknvelse om min reise ti1 spitsbergen. polarboken 1 9 6 e 7 0 : 74-123. norsk polarklubb. oslo. larsen. t. 1972: air and ship census of polar bears in svalbard j wildl. manage. 36. 562-570. larsen. t . 1978: the worldofrhe polar bear. hamlyn. london. larsen. t . 1983. polar bear denning and cubproducriori in sual bard. typewritten manuscript. 14 pp, larsen. t , jonkel. c . & vibe. c. 1980: satellite radio tracking of polar bears between svalbard and greenland. proc srh i n t . bear conference, maduon. in press. larsen. t . & norderhaug. m 1979: hvalrossen kommer tilbake t i 1 svalbard. norsk narur. 1 0 ( 2 ) . 44-47. lentfer. j. w 1976: environmental contaminants and parssites in polar bears. federal aid ro wildlife resrorarion reporr. 22 pp. lentfer. j w. & hensel. r j . 1980: alaskan polar bear denning. pp. 101-108 in martinka. c. j . & mcarthur. k. l . (eds.). bears their biology and management bear biology assoc. conf. ser. 3 . lano, 0 1970: the polar bear in the sbalbard area. xor. polarinsr s k r . no. 149. 103 pp. madsen, h 1961: the distribution of trichinella spiraiis in sledge dogs and wild mammals in greenland under a global aspect. meddelelser o m gronland 159(7). 124 pp. manning. t h. 1971: geographical variation in the polar bear can. wildl. s e r o reporr series 13 27 pp. martinez fernandez. a . r & duran, m. l s . 1981: some difference i n the biological behavior of vanous sibling species of trichinella pp. 35-39 i n kim, c . w . . ruitenberg. e j d teppema. j s . (eds.), trichinellosis. proceedtngs of rhe frfth inrt-rnarional conference on trichinellosis. reedbooks l t d . . surrey. england. nelson. g 5 . 1970. trichinosis in africa. pp. 47-92 in gould. s e . (ed ). trichinosrc in man and animals. c. c thomas. spnngfield. illinois nelson. g s . . black, e . & mikundi. j . 1966: comparative studies on geographical strains of trichinella spiralu 7ranr. roy. trop. med. hyg. 60, 471480. nelson, g . s . . rogers, r . . keymer, j . & davis. r 1976: xerio radiographic demonstration of calcified trichinella cy\ts in 2’2 pp. 96 pp polar bear diaphragm. trirhinella narioa in polar bears from moscow zoo. trans. roy. s o c . trop. med. h y g . 70. 10. ozeretskovskaya, n n . & uspensky, s . m. 1957: group infes tation with trichinella from polar bear meat in the soviet arctic. med. parasirol. 26. 152-159. ozeretskovskaya. n . n.. romanova, v. i. & bronstein, a . m. 1969: trichinosis from polar bear meat inthe soviet arctic. pp. 157-168in bannikov. a. g . , kishchinski. a . a. & uspensky. s . m. (eds.) the polar bearand its conservation in the soviet arcric, gidrometerologizdat. leningrad. parnell. i . w. 1934: animal parasites of north east canada. canad. field. nar. 18. 111-115. pawlowski. z . s . 1981: control of trichinellosis. pp. 7-20 in km. c . w . , ruitenberg, e. j . & teppema, j . s . (eds.), tnchinellosis. proceedings of rhe fifrh international confer ence on trichinellosis. reedbooks ltd., surrey, england. pereverzeva, e v., ozeretskovskaya, n. n. & veretennikova, n. l. 1973: development of larvae of trichinellae of an arctic bear strain in laboratory animals. itdarel’ sruo ‘nauka’ moscow, u d c 591. 69-974. 2 , 54-61. rausch. r . l. 1970: trichinosis in the arctic. pp. 348-373 in gould, s. e. (ed.), trichinosis in man and anirnah, c. c. thomas, springfield, illinois. rausch, r. l . , barpro, b . b , rausch, r . & schiller f. l. 1956: studies on the helminth fauna of alaska xxvii. the occurrence of larvae of trirhinella spiralis in alaskan mam mals. parasirology 42. 25f271. roth. h . 1949: trichinosis in arctic animals. nature 163, 805-806. steele. j . h . & arambulo, p.v. 1975: trichinosis a world problem with extensive sylvatic reservoir. inr. i. zoon. 2 , 6 s 7 5 . steele, j. h . & schultz, m . g. 1978: trichinellosis a review of the current problem. pp. 45-75 in kim, c. w. & paw lowski, 2. s . (eds.). trichinellosis. proceedings of rhe 4th lnrernational conference on trichinellosis. university press of new england. new hamshire. stirling. i . & cross. d . 1977: the ecology of the polar bear alongthe westerncoastofhudsonbay. can. wildl. seru. occas stirling, i . . calvert, w. & andriashek. d . 1980: population ecology studies of the polar bear in the area of southeastern baftin island can. wildl. seru. occas. pap. 44, 31 pp. stirling, 1 . & kiliaan. h . p. l. 1980: population ecology studies of the polar bear in northern labrador. can. wildl. seru. occas. pap. 42. 18 pp. taylor, m. k. 1982: the distribution and abundance of polar bears in the beaufort and chucki seas. phd. thesis, mimeo, 2 volumes. 353 pp. taylor. m. k., larsen, t. & schweinsburg. r . 1983: canni balism in polar bears. manuscript. 39 pp. thing. h . , clausen, 8. & henriksen, s. aa. 1976: finding of trichinella spiralis in a walrus in the thule district, northwest greenland. nor. ver. med. 28, 59. thorshaug, k & rosted, a . f 1956: researches on the preva lences of trichinosis in animals i n arctic and antarctic waters. nor. ver. med. 8 , 115-129. uspensky. s . m. 1979. polar bear huntingin the north of eurasia in the 18th to 20th century. pp. 122-141 in bannikov, a . g . , kishchinski, a . a , , uspensky, s . m. (eds.). the polar bear andirs conserciarion i n rhesoiiier arcric. gidrometerologizdat. leningrad. uspensky, s . m. & belikov, s. e . 1980: data on the winter ecology of the polar bear in wrangel island. page 117 in martinka, c . j . & mcarthur, k . l. (eds.), bears their biology and management. bear biol. assoc. conf. srr 3. pap. 33.64 pp. nitrogen uptake rates in phytoplankton and ice algae in the barents sea svein kristiansen and tove farbrot kristiansen. s. & farbrot. t. 1991: nitrogen uptake rates in phytoplankton and ice algae in the barents sea. pp. 187-192 in sakshaug, e.. hopkins, c.c.e. & britsland, n. a . (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, 12-16 may 1990. polar research l o ( 1 ) . uptake rates of nh:. no: and dissolved organic nitrogen (urea) were measured in phytoplankton and in ice algae in the barents sea using a "n-technique. no7 was the most important nitrogen source for the ice algae (f-ratio = 0.92). the in situ irradiances in the subsurface chlorophyll maximum and in the ice algal communities were low. the in situ nos uptake rate in the ice algal communities was light-limitcd. the in situ n o j and nh: uptake rates in the subsurface chlorophyll maximum were at times light-limited. i t is hypothesised that nhf may accumulate in low light in the bottom of the euphoric zone and inhibit the in situ nos uptake rate. -..i i,... svein kristiansen and tove farbrot, department of biology, marine botany section, university of oslo. p . o . box 1069. blindern. n-0316 oslo 3. norway (revised february 1991). introduction nutrient concentrations in the barents sea vary considerably through t h e year. during winter nutrient concentrations a r e high d u e t o vertical mixing of the water column. during spring and summer the water column becomes stratified, phytoplankton grows, and an oligotrophic surface layer develops south of the marginal ice zone. a t the same time a pronounced subsurface chloro phyll maximum is formed at the nutricline (kri stiansen & lund 1989; loeng 1989; rey & loeng 1985). several ice algal communities have been identified in the barents sea ( h o m e r et al. 1988). the ice algal biomass, especially in the sub-ice assemblage, may be very high, and has been suggested to be a n important part of the eco system in the barents sea (syvertsen 1991 this volume). irradiance is low in both the subsurface chlorophyll maximum (rey & loeng 1985) and in the ice algal communities (e. e. syvertsen pers. commun.), and algal cells in some of these communities have been shown t o be shade adapted (sakshaug 1989). kristiansen & lund (1989) found that nhf concentrations >0.8 vmol i ' significantly reduced no; uptake in the low light regime in the subsurface chlorophyll maxi mum. the uptake rates of nh;, no, and urea in these low light and often nutrient-rich environ ments, the subsurface chlorophyll maximum, and the sea ice algal communities will be discussed. materials and methods the samples from the subsurface chlorophyll maximum were collected during four cruises in the central parts of the barents sea in may-june and in august 1984 (kristiansen & lund 1989), in july-august 1985, and in may-june 1987. t h e ice algae were sampled during four cruises into the ice by divers using gentle suction from a submersible pump (l0nne 1988) or by scraping algae off the ice (fig. 1). it has been observed that the algal cells usually float directly beneath the ice, making quantitative sampling difficult. lspi tsbe rgen 0 20" 26" 32' fig. i . stations i n the barents sea where ice algal samples were collected. the curves represent the approximate southern limit of the sea ice during each of the four cruises. 1 ( a ) . k / v nordkapp in february-march 1987: 2 (a), kiv senja and k/v 4 (0). r/v lance in may-june 1986. andenes in april 1986; 3 (0). k/v andenes in may-june 1988: 188 s. krisriansen & t . farhrot the samples were diluted to contain less than s(b75 pg chl i ' before incubation. the values presented here have been corrected for the dilu tion procedure. t h e nitrogen uptake rates were measured using the stable isotope "n. t h e methods used are given in kristiansen & lund (1989). the uptake rates are calculated in situ absolute uptake rates in mol i ' hk' unless other wise stated. saturating amounts. 4.0 pmol i ' n h f or urea-n or 8.0 pmol no;. of the isotopes (95-99 atom%' ' i n ) were used in the experiments. the half-saturation coefficients used in the cal culations of the in situ rates were l . 3 ymol i ' for n h f , 1.8 pmol i ' for n o , and 0.2 umol i ' for urea-n. these half-saturation coefficients are typical for not-rich barents sea water con taining > 1 pmol i ' ( p e r s . observation): in no; -poor barents sea water ( < 1 pmol i i). the half-saturation coefficients for the three nutrients were 0 . 1 4 . 2 p m o l l i . t h e growth rate. 11. in doubl. h i , was calculated as: p = p * ( p n * l n 2 ) ' where i-, is summed in situ absolute uptake rate of no; + n h ; +urea in pmol i ' h ' and pn is particulate nitrogen in umol i ' . scalar irradiance beneath the ice was measured using a 4-rr collector (biospherical instruments inc.. model qsl-140). and the irradiance in the incu bator was adjusted accordingly with stainless steel nets. at one station, in march 1987. quantitative ice algal samples were incubated in in situ incu bation chambers. t h e chambers were acrylic cyl inders closed in o n e e n d . 11 cm in diameter and 950 ml capacity. tightly f i t acrylic lids were used to cap off the chambers after sampling. the iso tope was added through a septum mounted in each lid. the chambers were filled. capped off. and isotopes were added. all under the ice. and the chambers were left to incubate under the ice. results and discussion the n o t concentration was typically about 1 3 p m o l l ' in the whole water column during winter and below the pycnocline during summer (table i ) . i n the oligotrophic surface layer the no, concentration was usually not detectable. the concentrations of n h ; and urea were usually 4 . 3 pnol i ' . at stationswith a pronouncedsub surface chlorophyll maximum. however. a sub surface n h ; maximum was often found associated with the chlorophyll peak (table 2 ) . during the productive season. high nh: con centrations were found also in the ice/water interface (table 2 ) . in winter the nh: con centration was < o . i pmol i ' . the sampled ice algal biomass was very high and variable (table 3). though not unexpectedly considering the sampling methods used. the mean ratio between particulate carbon and nitro gen ( c : n) in the ice algae and in the water column in the marginal ice zone ( m i z , as defined in vincent 1988) were both close t o 7 which is typical for multispecies communities of phytoplankton (redfield et al. 1963). t h e mean ratio between chlorophyll a and particulate organic c (chl/c) was 2.6 times and 13.8 times higher in the ice algal communities than in the water column in m i z and in the oligotrophic surface layer south of m i z respectively (tables 3 and 6 ) . this indi cates that the ice algal communities were shade adapted (sakshaug 1989). t h e c and n values have not been corrected for non-phytoplankton carbon. and the chl/c ratios are minimum esti mates. a mixture of one-year and multi-year ice was found at the two northernmost stations (fig. 1 ) . and one-year ice dominated at the other sta tions ( pers. observations; syvertsen 1986, 1987, 1988; vinje 1987). t h e sub-ice assemblage was the dominating ice algal community both in one year and in multi-year ice. dominating species were nitzschia frigida and thalassiosira spp. in one-year ice and melosira arcdca in multi-year ice (syvertsen 1986. 1987. 1988: e . n. hegseth pers. commun.). the mean uptake rates in the ice algal com munities and i n the water column in m i z are compared in table 4. t h e summed absolute uptake rate ( n h ; + n o , + urea) in the ice algal communities was high and variable, mainly because the sampled biomass was variable. the tublr i . t!pical c o n c e n t r a t i o n s of no; i n h ; . u r e a n . a n d particulate o r g a n i c n i t r o g e n ( p n ) i n pmol i' i n t h e b a r e n t s sea d u r i n g w i n t c r a n d d u r i n g w m m e r in thc o l i g o t r o p h i c s u r f a c c la!er a n d i n d e e p w a t e r . summer o l i g o t r o p h i c deep s u i r i e n t w i n t e r s u r f a c c l a y s r w a t e r nitrogen uptake rates in phytoplankton and ice algae in the barents sea 189 table 2 . concentrations of n h ? in the subsurface chlorophyll maximum. in thc ofigotrophic surface layer, in the icc/scawatcr interface and in the water column 0.3 m under the ice during the productive season. range means i se samplc (pmol i ' ) ( p o l i ' ) n subsurface chloroph. max. 0.11-2.28 0.67 + 0.08 40 oligotrophic surface layer 0.09-0.39 0.25 2 0.02 23 ice/seawater interface 0.4g-2.51 1.17 f 0 . 4 2 i 0.3 m under the ice 0.05-0.58 0.33 + 0. i i 5 table 3. concentrations o f chlorophyll a ( p g l ' ) and of particulale organic nitrogen (pn in }tmoll-'). atomic ratlo between particulate organic carbon and nitrogen (c/n) and ratio between chlorophyll a and particulate organic carbon (chl/c in g/g) in the ice algal samples and in the water column in the marginal ice zone. mean * standard error and number of samples ( n ) arc given. sample chl pn chl/c c/n ( x 1000) n ~ ~~~ ice algae 1260 f 558 227 5 65 8.6 ? 0.5 41.4 2 5 . 2 "18 (9) hwater col. 2.0 2 0.6 1.11 ? 0.17 10.0 * 0.6 16.1 + 3.2 20 ~ 'chlorophyll a from 9 samples only h(personal observation) table 4 . summed nh; + no5 + urea-n absolute uptake ratc in nmol 1-i h l . i-ratio (no: uptake ratc divided by summed uptake rate) and nh; and urea uptake rate as % of summed uptake ratc in the ice algal samples. in one quantitative ice algal sample incubated in situ. in the water column in the marginal ice zone (miz). and at stations 905. 947 and 961 south of miz. mean 2 standard error and number of samples (n) are given. n.a. = no values available. sample summed uptake f % n h i % urea n ice algae 500 2 191 0.92 * 0.02 6 2 2 2 + i 15 ice algae, in situ n.a. 0.y6 0 3 1 "water column, miz 10 f 3 0.92 * 0.01 5 + 1 3 2 1 15 905, 26 m 4 0.00 80 20 i 947, 30 m 10 0.74 24 2 1 961, 30 m 15 0.00 100 0 1 a( pcrsonal observation). corresponding mean n growth rate, assuming 12 hours daily uptake, was 0.04 _t 0.01 doubl. d ' (mean and se, n -= 15). t h e n growth rates are minimum estimates because nitrogen was taken up at a reduced rate in the dark (fig. 2 and table 5), and because they have not been corrected for non-phytoplankton nitrogen. reported growth rates for ice algae are 3-8 times higher (see pal misano & sullivan 1985). t h e ratio between no; uptake rate and summed uptake rate (f ratio) is often used as an index of new production (eppley & peterson 1979; harrison e t al. 1987). the f-ratio was very high, and nh; and urea were negligible as nitrogen sources in the ice algal communities. high nh; concentrations were found in the ice/seawater interface at some of the stations (table 2) but not, however, in the uptake samples. t h e sampling procedure and dilution with filtered sea water may have diluted away any elevated nh; concentrations in the uptake samples. the relative importance of the three nitrogen sources may therefore be biased, and possibly the true mean f-ratio was lower than 0.92. this seems unlikely, however, because a similar f-ratio was found in o n e in situ incubation (table 4). a similar f-ratio was also found in the water column within the ice (table 4). t h e same sampling and dilution procedures were used in similar experiments in antarctica during the epos cruise, leg 1, in 1988. t h e infiltration 190 s. kristiunsen & t . furbrot a h h k 0 100 200 irradiance w o l m2 s l ) 0 10 20 30 40 50 irradiance ( p o i m-2 s.1) fig. 2 . maximum absolute uptake rates of nh; (0). no; (m) and urea-n ( a ) as functions of irradiancc. a . samples from the subsurface chlorophyll maximum at station 961. 30m. 4 june 1987: and b . samples from the sub-ice assemblage at station h k . 26 may 19% t h e arrows indicate the irradiancc at the sampling depths at n o o n sen. unpubl. values). olson (1980) found a lower mean f-ratio (0.71 ~ n = 2) in ice algal communities in antarctica but also claims that his f-ratios were minimum estimates. t h e f-ratio was 0 in the sub surface maximum a t stations 905 and 961 (table 4). a t the biomass-rich station 947, however, the f-ratio was 0.74 at 30 rn depth (table 4). similar variation in the f-ratio has been found in the subsurface chlorophyll maximum earlier (kri stiansen & lund 1989). typical maximum absolute nitrogen uptake rate versus irradiance curves from the subsurface chlorophyll maximum and the sub-ice assemblage are given in fig. 2. t h e maximum absolute nitro gen uptake rates in t h e subsurface chlorophyll maximum were light-saturated at the same irradiance as carbon uptake (91 pmol m-'s-l a t station 905; rey, pers. commun.). no definite light-saturation level was found for no; and urea uptake in the sub-ice assemblage. it is reasonable, however. based o n the values in fig. 2 , t o assume that the maximum absolute no, and urea uptake rates in the sub-ice assemblage were light-satu rated at about 100 pmol m-'s-i. t h e maximum nh; uptake rate was light-saturated a t 21 vmol m ? si (fig. 2b). these light-saturation levels are within the range of published values for c uptake in ice algal communities (burkholder & mandelli 1965; palmisano & sullivan 1985; pal misano et al. 1985; horner 1985). maximum nitrogen uptake rates at in situ irradiance are calculated as percent of light-saturated rates in table 5 . a linear relationship was assumed between maximum nitrogen uptake rates and irradiances <21-41 pmol m-? s-i in making the calculation. in situ irradiance at noon was low both in the subsurface chlorophyll maximum and in the sub-ice assemblage (table 5). even though the chl/c ratios indicated shade-adapted cells in both communities (table 6), the maximum nitrogen uptake rates at all stations in table 5 were light-limited. assemblage (horner et al. 1988) was the dom inating ice algal community encountered during the epos cruise, and t h e mean f-ratio was 0.96 (sd = 0.05. n = 5 ; s . kristiansen & e. e. syvert tuble.5. lrradiance at samplc dcpth at noon ( i . in btmol m ' 5 ' j and as percentage of surfacc irradiance ( % i \ ) , and in situ maximum uptake rate of no;. nh; and urca a5 pcrccntagc of light-saturated maximum rates in thc water column south of the marginal icc' zone and in thc ruh-ice assemblagc. n . a . = no values availahlc. stat i on depth i c i . r f no; (t nh; 5f urea 61 28 79 68 44 nitrogen uptake rates in phytoplankton and ice algae in the barents sea 191 table 6 . concentration of chlorophyll a (pg i ' ) , ratio between chlorophyll a and particulate organic carbon (chl/c in g/g), and concentrations of not. n h t and urea-n in p o l i ' in the water column south of the marginal ice zone and in the sub-ice assemblage. the ice algal samples were not collected quantitatively. n . a . = n o values available. chl/c station depth chl ( x 1000) no, nh: urea-n "905 905 "96 1 96 1 947 947 1 1 hk 10 26 10 30 10 30 ice algae ice algae 0.56 7.04 0.19 6.72 5.09 3.49 3844 8120 4.1 47.1 1.9 13.8 17.7 12.7 58.7 n.a. 0.0 0.0 0.0 0.0 0.4 2.6 7.3 4.8 0.09 0.53 0.17 0.21 0.17 0.59 0.10 0.03 0.20 0.17 0.03 0.03 0.12 0.04 n.a. 0.03 *oligotrophic surface layer except for nh: a t station 905 ( 2 6 m ) , the nutrient concentrations at stations 905 and 961 were low, close t o the detection limit (table 6), and it is not possible t o decide whether the in situ absolute uptake rates of nh: and urea in the subsurface chlorophyll maximum were light-lim ited or not. t h e f-ratio was 0 a t both stations (table 4), and the in situ absolute no, uptake was clearly substrate-limited a t both stations. t h e nh: concentration was significantly higher in the subsurface chlorophyll maximum at station 905 (26 m) than in the oligotrophic surface layer above (station 905, 10 m ; table 6). probably the in situ nh: uptake rate was light-limited in the sub surface chlorophyll maximum at station 905. sta tion 947 was sampled at 30 m depth, in not rich water below 1% light depth (table 6). however, the phytoplankton biomass was high in the upper 50 m, and n o pronounced subsurface chlorophyll maximum was found a t this station. the maxi mum absolute uptake versus irradiance curves a a n0;conccntration <0.5 pmol i-t no j concenlration >2.0 pmol i-! no; concentration 0.5.2.0 pmol i-' 1 2 3 ammonium concentration (lniol 1.') fig. 3. maximum specific no: uptake rate as a function of nh: concentration in the subsurface chlorophyll maximum. were similar t o the curves in fig. 2 a except that the no, curve was higher than the curves for both nh: and urea. no, was the major nitrogen source (f-ratio = 0.74, table 4), and the in situ uptake rates of both n o s a n d n h $ probably were light-limited a t this depth. high concentrations of nh: and of urea have been found in the subsurface chlorophyll maxi mum (table 2 ; kristiansen & lund 1989). these high nh: and urea concentrations were obviously produced by heterotrophic processes in the water column. typical values for irradiance in the subsurface chlorophyll maximum at noon were <25 pmol m-2 ski, and the irradiance varied with global radiation ( f . rey pers. commun.). it is suggested that light-limitation of the in situ uptake rates of nh: (and urea) was o n e major reason for this accumulation of nutrients. the data indicate that this actually was happening at stations 905 and 947 (tables 5 and 6). nh; concentrations >0.&1.0 pmol i ' reduced the maximum no, uptake rate drastically (fig. 3; kristiansen & lund 1989). a t some of the not-rich stations the maximum no, uptake rate was close t o zero, and consequently the in situ absolute no, uptake rate also was low. indirectly then, light limitation of the in situ absolute nhz uptake rate may affect the in situ absolute no, uptake rate. the in situ irradiance during sampling of the ice algae was well below the optimum irradiance for nitrogen uptake (fig. 2a, table 5 ) . irradiances a t the surface were not measured but both samples were collected o n dark snowy days. the concentration of no, in the sub-ice assem blage was high (table 6), and the in situ not uptake rate was probably light-limited. the 192 s . kristiansan & t . farbrot nh: and urea concentrations were low. and it is not possible t o decide if t h e in situ rates of these two nitrogen sources were light-limited or not. the absolute uptake rates of nh: and urea were very low in the sub-ice assemblage, however, and both were negligible as nitrogen sources for the ice algae (table 4 ) . typical under-ice irradiance in the barents sea was between 2 and 3 0 p o l m ? i s , the highest values measured on sunny days (e. n . hegseth pers. commun.). t h e no, concentration in the ice algal communities at the stations in fig. 1 was 2.6-10.8 fmol i ' . and the in situ uptake rate of n o t , the main nitrogen source at these stations, was probably light limited. acknowledgements. we acknowledge the generous assistance of the other cruise participants and the captains and crews of k / v s e n j a . wc thank e. n. hegseth and e . e . syvertsen for providing ice algal samples: f. rey for chlorophyll. no; and some of the particulate organic carbon and nitrogen data from the water column; e. n. hegseth for chlorophyll data and some of the particulate organic carbon and nitrogen data from the ice algal samples. and b. g . mitchell for light data. the incubations on board r/v lance were done by e. e . syvertsen. we also thank p. a . wheeler for reviewing an earlier draft of the manuscript. this work is a part of the norwegian research program for marine arctic ecology (pro mare) and was in part linanced by the norwegian research council for science and the humanities (navf) and the norwegian ministry of the environment. r!v g. 0 sars. r/v lance. k / v andenes. k/v nordkapp, and references burkholder, p. r . & mandelli. e. f . 1965: productivity of microalgae in antarctic sea ice. science 14y. 872-874. epplcy. r . w. & peterson, 8. j . 1979: particulate organic matter flux and planktonic new production in thc deep ocean. nature 2 8 2 . 677-680. harrison, w. g . . platt, t. & lewis. m. r . 1987: f-ratio and its relationship to ambient nitrate concentration in coastal waters. j . plankron res. 9 . 235-248. horner. r. 1985: ecology of sea ice microalgae. pp. 8>103 in horner. r. (cd.): sea ice biofa. crc prcss. florida. horner. r . a , , syvertsen. e . e.. thomas. d. p. & lange, c. 1988: proposed terminology and reporting units for sea ice algal assemblages. polar biol. 8. 24y-253. kristiansen. s . & lund. b. aa. 1989: nitrogen cycling in the barents sca-i. uptakc o f nitrogen in thc watcr column. d e e p sea res. 36, 255-268. loeng. h. 1989: ecological features of the barents sea. pp. 327-365 in rcy. l. & alexander. v. (cds.): procc,edirigs uf the sixth conference on the comiti arctique iiiternationul1.3 i s may l985. e. j . brill, leiden. l ~ n n e , 0. j . 19x8: a diver-operated electric suction sampler for sympagic (=under-ice) invertebrates. polar r e s 6. 135 1.16. olson. r. j . 1980: nitrate and ammonium uptakc in antarctic waters. limitol. oceunogr. 25. 1064-1074. palmisano, a . c. & sullivan. c. w. 1985: growth. metabolism. and dark survival in sea ice microalgac. pp. 131-146 111 horner. r. (ed.): sea ice biota. crc press. florida. palmisano. a. c., soohoo. j . b. & sullivan. c w. i y x s : photosynthesis-irrddiance relationships in sca ice microalgae from mcmurdo sound. antarctica. j . phycol. 2 l . 341-316. redfield, j . l.. kctchum, b. h . & rickards. f. a . 1963: thc influencc of organisms on the composition of seawater. pp. 2 6 7 7 in hill. m. n . (cd.): the s e a . v u l . 2 . john wilry and sons. rey, f. & loeng, h. 1985: the influence of ice and hydro graphic conditions on the development of phytoplankton in the barents sea. pp. 49-64 in gray, j . s. & christiansen. m e. (eds.): marine biology of polar regions and effecrs of stress on marine organisms. john wiley and sons. sakshaug. e. 1989: the physiological ecology of polar phy toplankton. pp. 61-89 in rey. l. & alexander, v . (eds.): proceedings of rlie sixrh coiiference oii the cornire arctiyrte internurional 13-15 m a v 1985. e. j . brill. lciden. syvertsen. e. 1986. pro mare-tokt mcd "lance". mailjuni 19x6. toktrapport fra isflora-gruppen. pp. 15-16 in mehlum. f . (ed.): rapport fra norsk polarinstitutts pro marc-tokt med "lance", barentshavet 21/5-10/6. 19x6. norsk polarrnsf. rapportserie nr. 2 9 . oslo (in norwegian). syvertsen, e. e . 1987: isalger. diatomecr vcd iskanlcn i bar entshavet. pp. 22-23 in syvertscn. e. e . (ed.): rapporr f r a pro mare-rokr 10 m e d k / v n o r d k a p p 2 4 . febrirar-10. mar\ 1987. biologisk institutt. universitet i oslo. oslo ( i n norweg ian). syvcrtsen. e . e. 1988: isalger. diatomccr vcd iskanten i bar entshavet. p. 25 in l ~ n n e . 0. j . (ed.): r a p p o r t . pru mare tokt n r . 1 4 . med k / v a n d e n e r 18. mai-2. jutri 1988. universitctct i t r o m s ~ . t r o m s ~ (in norwegian). syvertsen. e. e. 1991: k c algae in the barents sea: types of assemblages. origin, fate and role in the ice edge phyto plankton bloom. pp. 277-287 in sakshaug. e . , hopkins. c.c.e. & oritsland, n. a . (eds.): proceedings of the pro mare symposium on polar marine ecology. trondheim. 12 16 may 1990. polar research 10(1). vincent, w . f. 1988: microbial ecosystems o f a n t a r c t i c a cam bridge university press, cambridge. vinje. t . 1987: norsk polarinstitutt. isgruppen. pp. 12-13 in syvertscn. e. e. (ed.): r a p p o r t f r a pro m a r e t o k t l o m e d k l v n o r d k a p p . 24. februar-10. mars 1987. biologisk institutt. universitetet i oslo. oslo (in norwegian). devonian-carboniferous slivers within the basement area of north-east oscar i1 land, spitsbergen yoshihide ohta, claude lepvrier & friedhelm thiedig formed during an early compressional period in the opening of north atlantic ocean, a tertiary fold-thrust belt extends along the mid-to southern part of the western coast of spitsbergen. complex thrust structures involve the basement (caledonian and older) and many shallow dipping thrust faults dissect the overlying cover rocks (devonian and younger) in oscar i1 land in the northern part of the belt. some of these faults occur within the basement rocks with slivers or fault blocks of the cover rocks from south-western broggerhalvgya to innermost st. jonsfjorden in north-eastern oscar i1 land. six of the slivers contain carboniferous rocks and one is a fault-bounded block with devonian rocks. these steeply west-dipping faults form a complex fault system eofc (engelskbukta-osbornbreen fault complex) within the base ment area. the lithological units of the basement are separated by faults within the eofc, which is structurally continuous with the broggerhal vgya fold-thrust zone to the north and is thought to continue to the fold thrust zone on the south-eastern coast of st. jonsfjorden. some previous authors considered that the two lithologically contrasting vendian diamictites and intervening moefjellet formation are stratigraphically continuous and defined two separate tilloid successions in the present area. this interpretation has been extended over the whole of western spitsbergen. however, the present study indicates that these two tilloid formations and the moefjellet formation are separated by the faults, probably thrusts, within the eofc and are not in a continuous stratigraphic relation. therefore, the two-stage history of vendian glaciation seems questionable. y. ohta, norweginn polar institute, c/o ngu, b o x 5348 mnjorstiiu, n-0304 oslo, norway; c. lepvrier, tectonic. lobornton, esa 7072. p. and m. cirrie utiiwr~ity, 4 place jiissiru, 75252 paris cedex 0 5 . france: f. thiedig, institute of geology and pnlaeontologv. universih of miinstet-. corrensstrasre 24, 0-48149 miinster. gerrriany. several thinand thick-skinned fold-thrust zones develop along the west coast of spitsbergen. the largest island of svalbard archipelago (fig. i ) . this belt was caused by the tertiary diastrophism related to the early plate movement of the opening of the north atlantic ocean, and is generally referred to as the west spitsbergen fold-thrust belt. the trend of the belt turn5 from a nnw to a north-west direction, from inner st. jonsfjorden to b r ~ g g e r h a l v ~ y a ( b r ~ g g e r peninsula) in oscar i1 land. a complex thrust structure of carbonifer ous-tertiary sediments is developed in the penin sula, involving metamorphic rocks of the basement (orvin 1934: challinor 1967: hjelle & lauritzen 1982; dallmann, andersen et al. 1993; saalmann et al. 1997). the faults between the ohta et al. 2000: polar resenrch 19(2). 217-226 217 basement and the cover sediments (devonian to tertiary) follow the same trends as the belt. some thrusts at least two displacing the cover sediments in braggerhalvaya seem to extend southward, bounding different lithological units of the basement (fig. 1). since the 1960s, several localities of carboni ferous and devonian rocks have been recognized in north-eastern oscar i1 land (harland, horsfield et al. 1979; hjelle, ohta et al. 1979; winsnes & ohta 1988; dallmann, andersen et al. 1993), as narrow slivers and a block along the faults probably thrusts within the basement area. many previously unpublished field observations were incorporated i n the tectonic map of dallmann, andersen et al. (1993). in the lithostratigraphy of the vendian tilloid successions in oscar i1 land, waddams (1983) and harland, hambrey et al. (1993) identified two tilloid successions separated by a thick marble (fig. 1). these authors claimed that primary stratigraphic contacts exist in this area. this article describes the occurrences of carbo niferous and devonian rocks within the basement area of north-eastern oscar i1 land as presently known and suggest their structural significances both for the tertiary tectonics as well as the stratigraphy of the vendian tilloids in a general geological view. no detailed kinematics will be presented since the data are limited due to the difficult accessibility of the localities. description of the localities seven localities of devonian and carboniferous fig. i . (a) the svalhard archipelago. place name ahhreviations are: b = bellsund; h = hornsund; nf = ny friesland. rectan gle indicates area enlarged in (h). (h) distrihution of west coast diamictites along the south-western coast of spitshergen; kf = kongsfjorden; st = st. jonsfjorden; pkf = prins karls forland: if = isfjorden: bs = bellsund; hs: hornaund; trian gles =upper tilloids of harland. hamhrey et al. (1993); dotted = lower tilloids of harland, harnhrey et al.: hlack = lower tilloids of harland, hamhrey et al.. but the grenvillian unconformity conglomerates in our interpretation. rectangle indicates area enlarged i n (c). (c) geological map of eastern oscar i 1 land, showing the localities of described occurrences of devonian and carboniferous rocks. eofc = engelskhukta oshornhreen fault complex: we = welderyggen: do = dom kyrkja; bi = bispesetet; s p = spannklumpen: kr = kregnes toppen; pa = patronen; ka = kausen: circled numbers 1-7 are localities described in this paper. 718 devonian-carboniferous slivers within the basement area of north-east oscar i1 land rocks found as a fault block and narrow slivers are described below, from south-western braggerhal voya to north-eastern st. jonsfjorden (fig. ic). loculity 1. north of uversp?\.ra a thin sliver, 5-lom wide, of white sandstones with thin coal beds, presumed to belong to the lower carboniferous orustdalen formation and a grey massive limestone with siliceous concretions, presumed to be a part of the upper carboniferous scheteligfjellet formation (cutbill & challinor 1965; harland 1997). occurs on the south-western slope, ca. loom asl, of welderyggen and the southern slope of steenfjellet. the rocks are distributed along the fault-bounding micaceous schists of the bogegga formation of the kongs vegen group (orvin 1934) in the north and the non-tillitic sandy phyllites of the trondheimtjella formation (waddams 1983) in the south (table i ) . the sliver is discontinuous along the fault which extends south-eastward under the moraine of uversayra and uversbreen. the north-western extention continues to one of the thrust-displacing carboniferous strata in braggerhalvaya. the marginal fault planes of the carboniferous sliver are covered by scree, but their trend is estimated to be ca. 300-310‘ with steep to vertical dips. schistosities in marbles, schists and phyllites of the basement dip mainly 60-90’ w and sw and strike 135-180’-’. oblique to the boundary trend. while the beddings in the carboniferous sediments within the sliver show 10-15” w dips (fig. 2). subsidiary faults in the marbles near the boundary fault bear oblique normal striae plunging north west, suggesting a late extensional event already documented in braggerhalv~ya (lepvrier & geyssant 1984: lepvrier 1992: saalmann & brommer 1997: saalmann et al. 1997). about 2 km north-west of locality 1, red clastic beds with dolomites of the brogertinden forma tion occur along the fault. the bedding of these rocks has subparallel strikes with steep dips to the south-west. l o c u l i ~ 2. south-eastern edge of trondhein~ella trondheimfjella is the type locality of the vendian tilloids, the trondheimfjella formation (harland, horsfield et al. 1979; harland, hambrey et al. 1993: waddams 1983). definitive tillite occurs on the north-eastern slope of trondheimfjella, while siliceous phyllites, areno-argillaceous and calcar eous phyllites dominate structurally above and below. the rocks in the middle ridge and north eastern slopes are separated by a south-west dipping steep fault which, north-east of uversoyra, extends toward the north-west. at the south-eastem corner of trondheimfjella, a ca. l 0 0 m thick sliver of carboniferous sedi ments occurs in the foothill of the reverse fault which is the southern extension of the fault mentioned above, though the eastern boundary of the sliver is under a glacier. the rocks are red sandstones and poorly sorted conglomerates, with thin layers of coarse-grained sandstone. locally with a dolomitic matrix. a few thin limestone beds occur in the upper stratigraphic part of the t u b k i . stratigraphic scheme of eastern oscar i1 land, spitsbergen. (the author i s aware that this interpretation differs from that presented in the map hy hjelle. piepjohn et al. 1999.) middle carboniferous lower cdrboniferou\ devonian vendian neoproterozoic mesoproterozoic gipshuken group scheteligfjellet fin.: liiiiestones, sandstones brdggertinden fm.: congloniemtes. sandstones billefjorden group orustdalen fm.: \undm)nes, conglomerates. coal seams red bay group: red breccia and conglomerttes comfortlesshreen group trondheimfjella fm.: tilloids. phyllires. carhonates moefjellet fm.: carbonates kongsvepen group st. jonafjorden group tilloids, phyllites. quartzites. green phyllites nielsenfj. fm.: phyllites. carbonates steenfj. fm.: carbon:ite\ quartzites. preenschists bogegga fm.: schists, gneisses phyllites. carbonates. ohta et al. 2000: polar research 19(2). 217-226, 219 north uversaryra m n (10c.l) \i spond to a later phase of extension similar to that observed at locality i (fig. 2). fig. 2. stereographic projections of the measured structureq from locality 1 . lower hemisphere projections on equal area stereonet. heavy line = estimated marginal fault; thin lines = subsidiary faults; dots = fault stria, arrows indicate movement direction. i l ) and ( 2 ) refer lo the movement episodes measured on the same fault place: small open circles = pole to bedding: cross = pole to cleavage. succession. these lithologies are correlated with part of the billefjorden group and possibly with the braggertinden and scheteligfjellet formations (table 1). the carboniferous beds have roughly north south strikes with nearly vertical dips, though two measurements have gentle dips, and are younging eastwards (fig. 3). poles to bedding concentrate along a great circle, which suggest a fold with a subhorizontal axis. bedding and the boundary fault are subparallel and this may suggest an orthogonal compression structure prior to, or during, the faulting. the possibility of different stages of folding and faulting cannot be excluded. the boundary fault along the west side of the carboniferous sliver strikes roughly north-south and has a steep westerly to vertical dip, locally with steeply south-plunging slip striations. a subsidiary fault with a moderate south-east dip also has a moderate south-south-east plunging slip striae, showing normal and dextral fault movement components. two other subordinate faults strike nearly perpendicular to the boundary fault with a normal slip. the successive normal fault move ments are consistent with each other and corre loculity 3. south-western trotidheimfiellu several subvertical, westerly dipping steep faults bound sandy-shaly phyllites with thin marble layers of the trondheimfjella formation against thick marbles of the structurally overlying moe fjellet formation around the westernmost peak, domkyrkja of trondheimfjella. since stratigra phically lower marbles in the west overlie the tillitic phyllites in the east, the fault zone is considered to be a thrust zone. this thrust zone passes bispersetet in the southern part of trond heimfjella, where it incorporates slivers of carbo niferous rocks. a thin, brecciated, grey limestone with a trace of a coal seams occurs at the pass between the peaks 830 m in the west and 810 m in the south east in bispersetet. these may be correlated with the scheteligfjellet formation. the fault zone extends with a ca. 330" strike and subvertical to steep westerly dips (fig. 4). though the fault itself is covered by scree, and passes through the pass between the 830 m and 860 m peaks in the north west. beddings in the carboniferous limestone strike mainly wnw-ese with steep south-west dips. this obliquity may be explained by a dextral south-eastern trondheimfjella m,! (loc.2) fig. 3. stereographic projections of the measured structure5 from locality 2. thick line = observed reverse fault: legend otherwise the same as for fig. 2 . 220 devonian-carboniferous slivers within the basement area of north-east o s c a r i1 land south-western trondheimfjella (loc.3) fig. 4. stereographic projections of measured structure\ from locality 3. for legend see fig. 2 . additional: small square\ with short lines = axes of crenulation and mesoscopic folds in the phyllitic rocks. for explanations of ( i ) and (2). refer tv thc text. transpression, or by a rotation during supposed thrusting, though the possibility of different stages of formation of the fold and fault cannot be excluded. two folds with axes of different direction are inferred from the great circles of phyllitic cleavages: 1 ) one fold with a gentle north-east plunging axis; and 2) one with a gentle south-east plunging axis. n o overprinting relationship, which could signify a polyphase folding. has been identified, except for a young episode of crenula tion formation. the western slope of the 8 3 0 m peak is composed of a wide scree of white sandstones. possibly billefjorden group, but without solid exposure. the rocks seen in the scree are similar to those across a glacier to the south at locality 4a. ca. 500 m perpendicular to the strike, but their relation is unknown due to ice cover. phyllite zone occurs between the carboniferous rocks (fig. 5d). the southern boundary fault is not exposed, but its south-east extension is observed at locality 4 b , having a strike in 140" and steep westerly to vertical dips (fig. 5b). to the south of the fault are sandy siliceous phyllites with strong cleavages of north-south to north-west-south-east strikes and about 5-10' w dips. the rocks are typical tillites around 4b. containing subangular dolomite and quartzites clasts, less than 15 c m in size, scattered in a coarse-grained, phyllitic sandstone matrix. the northern border is under a glacier. the carboniferous rocks in the upper part of the locality are gritty sandstones, containing very thin seams of coal, and conglomerates with round quartzite clasts, less than s c m across, having north-west-south-east strikes and 70-80" ne dips. cross-bedding observations show that the beds are inverted. the narrow sliver of basement rocks in the middle of the ridge is bounded by roughly 130 135' striking steep faults, subparallel to the southern boundary fault. with shallow south-east plunging striations with slip direction indicating a dextral oblique slip movement (fig. sa). the rocks are quartzitic phyllites, sandy, grey-black phyllites with or without garnet, and brown dolostones, a total of ca. 5 0 m in width. their cleavage has north-south to nne-ssw strikes and moderate to gentle easterly dips. mesoscopic fold axes trend ene with moderate plunges and crenulation axes i n a south-west trend with gentle plunges. the cleavages of the basement rocks in the south and middle of the carboniferous rocks together may form a rough great circle around inferred nne ssw horizontal axis, subperpendicular to the carboniferous structure, which does not confirm with the observed mesoscopic fold axes. this inferred fold may represent a post-caledonian structure. the carboniferous rocks in the lower part of the locality are white sandstones and conglomerates with some plant fragments. the cross beddings show that the beds are in stratigraphically normal position. they have a similar bedding trend to the carboniferous rocks in the upper part. two sets of nne-ssw-striking, conjugated or loccility 4a. sniad ridge extending to the north in south-enst bid1 sinionsenfjellet this narrow ridge consists of white sandstones and conglomerates with thin coal seams and plant fragments in coarse-grained sandstones. which can be correlated with the orustdalen formation of the billefjorden group. a narrow fault-bounded pseudo-conjugated normal faults with steep to moderate east or west dips, occur within the carboniferous rocks (fig. sa). the bedding orientations of the carboniferous rocks, inverted in the upper and upright position in ohta et al. 2000: polar rrsenrch 19(2), 217-226 22 1 a . nordenfjeldskebreen fig 5 . stereographic projections of (a) south-east bull simontenfjellet. locality sa, (b) southern bull simonsenfjellet. locality 4b. and ( c ) north-west bull simonsenfjellet, locality sc, as well as (dl schematic profile of the northern ridge. far legend see figs. 2 and 4. in (d), dark m o w s = stratigraphic younging directions; cb = carboniferous; ss = sandstone: is = limestone; mb = marbles: phy = phyllite; till = tilloids. the lower parts, indicate an overturned fold with a of bull simonsenfjellet. this fault separates a ca. north-west subhorizontal axis. it can be speculated 100 m thick marble of the moefjellet formation in that this fold was formed by a synthetic compresthe north-east from phyllitic vendian tilloids in the sional structure of an assumed dextral oblique, south-west on the northern ridge. the boundary conjugated faults mentioned above. but it may also between the banded schistose marbles and phyl be older than the faulting: a thrust-related lites does not always show evidence of displace deformation. ment around this locality, but local slickenside with moderately plunging slip striation has been locality 4 b . southern bull s i m o n s e t ~ e l l e t the southern boundary fault of locality 4a extends to the south-east and passes a pass west of spannklumpen, having 140' trend with a steep north-east dip (fig. 5b). there it separates the thick banded marbles of the moefjellet formation, which form spannklumpen to the east, from a tillitic phyllite to the west. the marbles have north-west-south-east strikes and 60-70'' sw dips, while the tillitic phyllites have east-west strikes and 0-30 dips. a scree of white sandstones of the carboniferous occurs along the fault on the south-western slope of spannklumpen, but no bedrock exposure has been seen. observed at a few exposures (fig. 5c). the banded marbles to the north of the boundary are commonly brecciated at the contact to the phyllites and are locally stained yellow-brown by sulphide mineralization. on some profiles of local ridges branching to the north-east, the general structure of the banded marbles and the phyllites is slightly oblique across the boundary; therefore a fault is inferred. the quartzites and sandstones, ca. 2.2 m in total thickness, along the boundary could be of carboniferous age. but this is difficult to judge due to their strong shearing. these observations do not clearly confirm a fault at this locally, since displacement might possibly be accommodated along cleavage planes of the phyllitic rocks, but some dislocation along the boundary between the banded marbles and 4c. north-west sitnonsenfjellet tilitic ,,hyllites can be inferred, since the inferred the southern boundary fault of locality 4a fault is the northern extension of faults at extends to the north-west along the northern slope localities 4a and 4b. 222 devonian-carboniferous slivers within the basement area of north-east oscar i1 land loculity 5. southern tuslingane the carboniferous scheteligfjellet formation, the northern half of the tuslingane nunataks are composed of phyllitic tilloids that extend from trondheimfjella southwards. the cleavages are with nnw-sse strikes and moderate west dips. a distinct banded marble, 10-15 m thick, occurs in the middle part. black phyllites occur to the south of the marble and they have cleavages emphasized by the black, shiny surface of the bituminous material. with north-west-south-east strikes and moderate south-west dips and gentle west-plun ging mesoscopic fold axes. such an extremely graphitic cleavage has not been seen in the basement rocks. therefore, these rocks are thought to be derived from coal-bearing carboniferous rocks. an east-west-striking vertical fault separates the bituminous phyllites i n the middle of the nunataks from a grey limestone. ca. 20 m thick, i n the south. the bedding of the limestone has a north-west strike and a moderate south-west dip. sandstones and thin shale beds occur further south of the nunataks. fossils of plant fragments indicate the sandstones belong to the billefjorden group and the limestone to the scheteligfjellet forma tion. no observation on shear sence in the faults has been obtained. a 3 4 m thick dolerite dyke, probably of mesozoic, occurs in the north-eastern part of the nunataks. localih) 6. kregizestvppen the eastern half of this high nunatak consists of thick dark grey, crystalline dolostones, partly sandy. of the steenfjella formation of the kongsvegen group (orvin 1934). near the top, a vertical, north-west-south-east-striking fault sepa rates the dolostones from tillitic phyllites to the west. the tillitic phyllites have north-west-south east strikes and moderate south-west dips and contain quartzite and thin schistose marble lenses. a massive grey limestone, locally brecciated and siliceous with a brown colour. occurs on the lower part of the western slope. bounded by a north-south-striking, steep west-dipping fault. fault striae are horizontal and reveal sinistral displacement, shown by the slip direction of the striae. within the limestone. another fault with a similar attitude bears normal dip-slip striations. this limestone unit is presumed, though no critical supporting evidence has been found, to belong to since it lacks schistosity a n d has a fine-grained texture. the westernmost part comprises strongly cre nulated, biotite-bearing sandy phyllites with scat tered quartzitic clasts, having cleavages of wsw ese strikes and moderate south dips. a small isolated nunatak further to the west consists of sandstone scree, possibly of the billefjorden group. but no solid exposure has been seen. loculiq 7. south-east haruldfiellet a steep ridge to the south-east into osbornebreen is entirely composed of red-coloured, poorly sorted conglomerates. angular clasts are quartzites and carbonates of various colours with a clast supported texture; the matrix is red-coloured sandstone. plant fragments, similar to those found by gjelsvik (1974) on lovcnayane in inner kongsfjorden, were found at this locality (t. s. winsnes, pers. comm. 1994), and indicate a devonian age for these rocks. bedding does not develop well and has 80-70" strikes. measured dips are mostly 20-30" se, but vary. a nnw striking subvertical fault marks the western limit, but a local unconformity has been observed (h. d. maher jr., pers. c o r n . 1994). the eastern boundary is situated under a glacier. a tilloid with a calcareous sandy matrix and thin marble lenses comprises the western part of the nunatak. the cleavages of rocks have north-west south-east strike and a moderate west dip. dolostone layers are intercalated in the western ridge and nne-ssw-trending breccia zones with sulphide mineralization developed in the western most nunataks. a dolerite dyke of 1 m thickness, probably mesozoic, occurs with an east-west strike. the tillitic phyllites further west commonly contain quartzite layers. discussion definition of the eofc fuiclt con7plex all devonian and carboniferous rocks described above occur along faults in a zone that extends from south-westem br@ggerhalv@ya to inner st. jonsfjorden. the zone shows a very gently curved distribution from a north-west-south-west to a nnw-sse strike. the north-eastern boundary of the zone, includ ohta et al. 2000: polar research 1 9 ( 2 ) , 217-226 223 ing faults with the carboniferous slivers at localities 1 and 6 (fig. l), separates the kongsvegen group to the north-east from the tilloid-bearing phyllitic and carbonate successions to the west. locality 7 is located on the southern extension of this fault. the devonian rocks at locality 7 seem to overlie the tillitic phyllites; though this is not confirmed on the outcrops, at least there are no micaceous schists similar to those of the kongsvegen group i n the moraine blocks along the eastern foothill of the nunatak. thus, the eastern boundary fault is located to the east of locality 7, and therefore this locality is included in the fault zone. the south-westem boundary of the fault zone is the connection of the westernmost localities of the carboniferous slivers in bull simonsenfjellet, at localities 4a, 4b and 4c, but the southern part is located around the distribution boundary between the moefjellet marbles plus tillitic phyllites in the east and the mesoproterozoic st. jonsfjorden group to the west. it seems possible to consider all the faults described above as belonging to a 3-5km wide basement fault complex, the engelskbukta-os bornebreen fault complex (eofc in fig. lc). this fault complex contain several subparallel faults, bounding various lithological units of the vendian tilloids and distinctive marbles of the moefjellet formation, both neoproterozoic, and separates these rocks from high-grade metamorphic rocks of the kongsvegen group to the northeast and from the st. jonsfjorden group to the south-west of the eofc; both are considered to be mesoproterozoic. the slivers of carboniferous rocks and a block of devonian rocks are distributed along the faults within the eofc. the connection of the faults within the eofc as illustrated in fig. l c is highly speculative, due to complexity within the fault complex and small occurrences separated by large glaciers. linkage of the fuult complex to the north-west of the eofc, a multiple thrust complex. involving both basement and post devonian sediments, is developed in broggerhal vaya (orvin 1934; challinor 1967; manby 1988; saalmann & blommer 1997; saalmann et al. 1997). the north-westem parts of two faults of eofc are directly continuous with the faults of the braggerhalvaya thrust complex. since most other faults within the eofc have similar general nature, they are also considered to be thrusts. this suggests that the carboniferous slivers occurring along the faults of eofc are parts of the carboniferous sediments that were deeply buried into the basement by an as yet unknown mechan ism, most likely caught into thrusts (saalmann 1999; piepjohn et al. in press). kinematics of fault movement are suggested at some localities. but the information is fragmented and no systematic interpretation can be made at the present stage. a well developed fold-thrust zone is developed in the south-eastern coast of st. jonsfjorden around vegardfjella and wittenburgfjella (winsnes & ohta 1988; welbon & maher 1992). the carbo niferous rocks of this area are underlain by a basement of low grade, tillite-bearing neopro terozoic rocks, while to the west is the st. jons fjorden group. accordingly, this zone can be con sidered the southern extension of eofc, which is underlain by the neoproterozoic basement, while the exposing structural level is shallower in the south than that i n the north of st. jonsfjorden. it is therefore proposed that the eofc repre sents a deep structure of the tertiary fold-thrust belt, developed along the basement and cover boundary zone i n western spitsbergen. the present observations are not enough to corroborate this hypothesis and detailed kinematic of polyphase deformation history as previously studied i n other parts of the fold-thrust belt (challinor 1967; lepvrier & geyssant 1984; lepvrier 1988. 1992; manby 1988; gabrielsen et al. 1992; dallmann, andersen et al. 1993; braathen & bergh 1995; maher et al. 1997). lithostrurigruphy of the vencliun rilloids latest proterozoic tilloids in svalbard provide an important geological record of vendian glaciation (fig. lb). harland, hambrey et al. (1993) inter preted the field relationships between the comfort lessbreen group, trondheimfjella and moefjellet formations in oscar i1 land as stratigraphically conformable. referring to the two stages of vendian glaciation known in n y friesland (north-east spitsbergen), finnmark (northernmost norway) and eastern greenland, they considered that the trondheimfjella formation and the comfortlessbreen group can be correlated to the lower and upper tillite successions, respectively. these two have different lithologies in oscar i1 land. the lower succession is characterized by 2 24 devonian-carboniferous slivers within the basement area of north-east oscar i1 land intercalations of many carbonate layers and has mainly calcareous sandy matrices, while the upper formation and that with quartzites i n the west is identical to the comfortlessbreen group. there is one contains many quartzite layers and clasts of granitic rocks (waddams 1983; harland, hambrey et al. 1993). the idea of two tilloid successions separated by a marble succession has been applied by harland (1978) and harland, hambrey et al. (1993) to interpret the diamictites in west-central and south western spitsbergen along a ca. 2 5 0 k m long basement belt (fig. lb). all lower “diamictites” in the belt. e.g. the konglomeratfjellet conglomerates i n the south of bellsund (dallmann. hjelle et al. 1990) and the slyngfjellet conglomerates northern coast of hornsund (birkenmajer 1992; ohta & dallmann 1998). have been correlated with the trondheimfjella formation. thick marble succes sions above these diamictites in chamberlindalen in the south of bellsund and the hoferpynten marbles in hornsund have been compared with the moefjellet formation, which has been placed between two tilloid successions. but these carbo nate successions have been also correlated with the akademikerbreen group of ny friesland (e.g. birkenmajer 1992), and the akademikerbreen carbonates contain pre-vendian microfossils in ny friesland (knoll e t al. 1989). our field observations in north-eastern oscar i1 land show that the two tilloid successions, the trondheimfjellet formation and the comfortless breen group, and the moefjellet formation i n between, are separated by faults which involve carboniferous slivers. these three formations do not show any primary stratigraphic relation, except for the carlsfjella area, and are completely dismembered by faults. while the lithology of the two tilloid successions is contrasting. harland. hambrey et al. (1993) stated that clasts of granitic rocks are restricted to the comfortlessbreen group, but such clasts were also found in the trondheimfjella formation, on the southern slope of bjorvikfjellet. carlsfjella. located to the south-west of locality 7 in the southernmost eofc, north-east of st. jonsfjorden (fig. lc). consists entirely of tilloids and various phyllites. the tilloid succession includes several thin marble layers in the middle part of haraldfjellet (west of locality 7 ) and kausen. while it is interbedded with many quartzite beds in the western part from patronen to valentinryggen, without any observable struc tural discontinuity. the marble-bearing lithology in the east is similar to the trondheimfjella no thick marble succession similar to the moe fjellet formation between the two lithologically different tilloid successions. this is the only locality in the basement terrain of western spitsbergen where two contrasting lithologies of vendian tilloids occur without any structural break and with primary stratigraphic relations. there fore, there is no evidence of two tilloid successions separated by a thick marble in oscar i1 land; accordingly, the application of the idea of two successions of vendian tilloids, separated by a period of carbonate deposition, to the whole of western spitsbergen (harland, hambrey et al. 1993) is questionable. existence of two lithologically contrasting tilloid-bearing successions is acceptable and all observable tilloids in western spitsbergen may show one thick unit including both of these lithologies. accordingly, all tilloid successions in western spitsbergen have been informally called the west-coast diamictite unit in recently pub lished maps (dallmann, hjelle et al. 1990; dallmann, andersen e t al. 1993; ohta & dallmann 1998). if this is the case, western spitsbergen has a different depositional history than north-eastern svalbard and other regions such as northern scandinavia and eastern greenland, and might represent an exotic terrane juxtaposed during the caledonian orogeny. ac.trion.lrr/~t.r,ir,~rs. much unpublished information has been shared by t. s. winsnes and a. hjelle (norwegian polar institute) and e. tveten (norwegian geological survey). comments from. and discussion with, dr. h. d. maher jr. are much appreciated. part ofthe financial support was given by the french-norwegian science cooperation program. prof. m. bjgrnerud kindly improved the language of this paper. references braathen, a. & bergh, s. 1995: kinematics of tertiary deformation in the basement-involved fold-thrust complex, western nordenskiold land. svalbard: tectonic implications based on fault-slip data analysis. trctonoplijsics 249. 1-29. birkenmajer. k. 1992: precambrian succession at hornsund. south spitsbergen: a lithostratigraphic guide. studin geol. challinor. a. 1967: the smucture of breggerhalveya, spits bergen. gt.01. m a g . 104, 321-336. dallmann. w. k.. andersen. a,. bergh. s. maher, h. d., jr. & ohta. y. 1993: t r r h i y fold-und-thrust belt of’ sp;i.dwrgeti, siulhurd nor. polarinst. maid. 128. dnllmann. w. k., hjelle. a,. ohtn. y., salvigsen, 0.. bjornerud, fd. 98* c 6 6 . ohta et al. 2000: polar reserrrch 1 9 ( 2 ) , 217-226 225 m. g.. hauser. e. c.. maher, h. d.. jr. & craddock. c. 1990: geoliigicul niap ofsccilbard i : 100,000, bi ig. van keiclen jjordm. nor. pulririnst. teniakart is. gubrielsen, r. h., klgvjan, 0. s.. haugsbg. h., midb@e, p. s., ngttvedt. a,. rasmussen, e. 81 skott, p. h. 1992: a structural outline of the forlandsundet graben. prins karls forland, svalbard. nor. geol. tidsskr. 72. 105-120. gjeljvik. t. 1974: a new occurrence of devonian rocks i n spitsbergen. nor. polurinsr. arbok iy72, 23-28. harland. w. b. 1978: a reconsideration of late precambrian stratigraphy of southern spitsbergen. poluiforschung 4 8 . 4 4 61. harland, w. b. 1997: the ,qeology of s ~ d b a r d . g e d soc. mernoir 17. london: geological society of london. harland. w. b., hambrey. m. j. & waddams, p. 1993: the vendiun geology of svalbard. nor. polririnsr. skr. 193. harland. w. b., horsfield. w. t., manby, g. m. & morris, a. p. 1979: an outline pre-carboniferous stratigraphy of central western spitsbergen. nor. polnrinst. skr. 167, 119-143. hjelle, a. & lauritzen. 0. 1982: geologicni niup of swfburd i : 500,000, 3g, spitsbergen norrhcw purl, nor. polarinst. skr. 154c. hjelle. a., ohta, y. & winsnes. t. s . 1979: hecla hoek rocks of oscar i1 land and prins karls forland, svalbard. nor. polurinsr. sxr. 167. 145-169. hjelle. a,, piepjohn, k., saalmann, k., ohta. y., salvigsen, 0.. thiedig. f. & dallmann. w. k. 1999: geological niap of swilbard i : 100,000. a7g. kongsfiorden. nor. polurinsr. teintrkurr 30. knoll, a. h.. swett. k. 8: burkhardt, e. 1989: paleoenviron mental distribution of microfossils and stromatolites in the upper proterozoic backlundtoppen formation, spitsbergen. brcli. geof. soc. am. 95. 1293-1302. lepvrier. c. 1988: relais compressifs et distensit's entre dkcrochements dans la c h a h e tertiaire du spitzberg (sval bard. norvege). (compressional and extensional relay zones along the west spitsbergen strike-slip belt [svalbard, nor way].) coniptes rendiis a c u d h i e sciences, lome 307, serie i i . 4 0 9 4 14. lepvrier. c. 1992: early tertiary paleostress distribution on spitbbergen: implications for the tectonic development of the western fold-and-thrust belt. nor. geol. tid.sskr. 72. 129-1 35. lepvrier. c. & geyssant. j. 1984: tectonique cassante et champs de contrainte tertiaires le long de la marge en coulissement du spitsberg. corrklations avec les mkcanismes d'ouverture de la nier de norvtge-groenland. (brittle tectonics and tertiary palaeoslress field along the spitsbergen strike-slip margin. correlations with the opening of the norwegian-greenland sea.) annulus sor norcl ciii. 333-344. maher. h. d., jr.. bergh. s.. braathen. a . & ohm, y . 1997: svartfjella. eidembukta. and daudinannsodden lineament tertiary orogen-parallel motion i n the crystalline hinterland of spitsbergen's fold-thrust belt. tectonics 16(1), 88-106. manby, g. m. 1988: tertiary folding and thrusting i n nw svalbard. nor. polurinsr. r u p p e r . 46, 17-20, ohta. y. & dallmann, w. k . (eds.) 1998: ceologictrl inup of svulbard i : 100.000, 8 i 2 c . torellbreen. nor. polarinst. tertiuktrrt 29. orvin. a. k. 1934: geology sf rlie kings buy region, spits bergen. skrlfrer oni swlburd og ishuret 57. norwegian polar institute. piepjohn. k., thiedig. f. & manby. g. m. in press: nappe stacking i n the br@ggerhalv@ya. geologisrhes jahrbuch. saalmann, k. 1999: kinenintik des terriiiren deckenhairs irn wesr-spitzbergeii fulreiirind u ~ ~ e r s c h i e h i ~ n g s g i i r r ~ ~ l , ( k i n e m r i c s of tertiury nuppe srriictures in rhe west spitsber,pen ,fiiult and riiriisr belt.) phd thesis. geologisch-pal~ontolo gisches institut, westfdische wilhelms universitiit. saalmann. k. & brommer. a. 1997: stratigraphy and structural evolution of eastern braggerhalv@ya. nw spitsbergen. miinst. forsch. geol. pnttionrologie hf; 8 2 , 147-164. saalmann. k.. piepjohn. k . & thiedig, f. 1997: involviering des tertiars von ny-alesund in den alpidischen deckenbau der br0ggerhalvbya. nw spitsbergen. (involvement of the ny alesund tertiary strata in the alpine nappe structure of brcaggerhalvgya.) miinst. for.wh. geol. puliiontologie h f : 82. 129-145. waddams, p. 1983: the late precambrian succession in northwest oscar i1 land, spitsbergen. geol. mug. 120. 233-252. welbon, a. l. & maher, h. d., jr. 1992: tertiary tectonism and basin inversion of the st. jonsfjorden region. svalbard. j . srruct. geol. 1 4 ( l ) , 41-55. winsnes, t. s . & ohta. y . 1988: fold structures of carboniferous to triassic rocks in the inner part of st. jonsfjorden. nor. polarinst. rupp.ser. 46, 21-24. 226 devonian-carboniferous slivers within the basement area of north-east oscar i1 land lipid composition of phytoplankton from the barents sea and environmental influences on the distribution pattern of carbon among photosynthetic end products r. james henderson, rolf e . olsen and hans c. eilertsen henderson. r. j . , olsen, r. e. & eilertsen, h. c. 1991: lipid composition of phytoplankton from the barents sea and environmental influences on the distribution pattern of fixed carbon among photosynthetic end products. pp. 229-237 in sakshaug, e . , hopkins, c. c. e. & (dritsland. n. a . (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim. 12-16 may 1990. polar research ! & i ) . the colonial algae phaeocystis pouchetii and dinobryon pellucidum dominated the phytoplankton crop at three stations in the polar front area of the barents sea. lipid extracted from the seawater containing the phytoplankton was dominated by neutral lipid classes, particularly triacylglycerols. and phospholipids were more abundant than galactolipids at all stations. polyunsaturated fatty acids comprised between 15 and 26% of fatty acids of total lipid. of the carbon assimilated into lipid over 24 hours, 40% was.located in the neutral lipid fraction. phospholipids contained a smaller proportion of fixed carbon than galactolipids. no defiinte relationships were observed between the distribution of fixed carbon in photosynthetic end products and the temperature or irradiance at which the phytoplankton was incubated. at a constant irradiance of 8.5 pmol rn-*s-l, the highest proportion of fixed carbon was recovered in protein at 4.5"c, but at 1.5'c most radioactivity was present in low molecular weight compounds. regardless of incubation conditions. lipid always contained less than 30% of total assimilated carbon. r. james henderson and rove. olsen, n. e . r.c. unit of aquatic biochemistry, school of natural sciences, universiry of stirling, stirling fk9 4la scotland, u k ; hans c . eilertsen, aquatic biology group, norwegian college of fisheries science. uniuersily of tromsc. n-9000 tromse. norway (revised december 1990) introduction it is well known that irradiance and temperature are important variables in controlling phyto plankton primary production in polar and tem perate regions (harrison & platt 1986; mortain bertrand et al. 1988). several quantitatively important phytoplankton species in arctic/ northerly waters, among them phaeocystis pou chetii, adapt to low light by increasing their pho tosynthetic efficiency (eilertsen et al. 1989a; palmisano et al. 1986). temperature is known to control the rate of light saturated photosynthesis, and an increase in the activity of ribulose-1,5 biphosphate carboxylase may occur in phy toplankton as an adaptation to growth at low temperature (mortain-bertrand et al. 1988). other adaptations to low environmental tem peratures may also exist in arctic phytoplankton. for example, temperature is known to influence the lipid composition of photosynthetic marine algae grown in batch cultures whereby a decrease in growth temperature corresponds with an increase in the degree of unsaturation of the com ponent fatty acids (ackman et al. 1968; hen derson & mackinlay 1989; mortenson et al. 1988). this is in keeping with the general phenomenon of homeoviscous adaptation which maintains the fluid state of biomembranes in poikilotherms as environmental temperature falls. laboratory studies of the influence of temperature on fatty acid composition in algae have not employed temperatures as low as those encountered in arc tic waters. although the lipid composition of phy toplankton sampled in temperate waters has been studied (kattner et al. 1983; claustre et al. 1990), little information is available for the lipid com position of natural populations of arctic phy toplankton. it is not known whether the lipids of arctic phytoplankton show any special adap tations to environment. the incorporation of up to 80% of fixed carbon into lipid by field populations of antarctic phyto plankton has been attributed to low environ mental temperatures coupled with low ambient light intensities (smith & morris 1980a, b). in laboratory cultures of the cryptomonad chroo monas salina, the proportion of carbon fixed into lipid is influenced more by growth tem perature than by light (henderson & sargent. 230 r . j . henderson. r . e . olsen & h . c . eilertsen 1989). extrapolation of this finding to natural phytoplankton populations would suggest that low temperature rather than low light enhances the assimilation of carbon into lipid in polar waters. the present study had two aims: firstly to deter mine the lipid composition of phytoplankton taken from a polar front situation, and secondly to examine the influence of low temperature and light on the distribution pattern of fixed carbon within the various end products of photosynthesis, particularly lipids. materials and methods hydrography and phytoplankton studies were carried out on board rjv johan r u u d . the hydrographic parameters of the sta tions at which phytoplankton were sampled in the present study have already been described in detail elsewhere (hansen et al. 1989). the sta tions were located in the mixing zone between atlantic and arctic water masses at the edge of the drift ice. samples of seawater containing phytoplankton were collected by niskin bottles. irradiance was measured using a lambda li-185 quantum meter equipped with a spherical sensor. chlorophyll a and phaeophytin determinations were carried out as described by eilertsen et al. (1989a). for analysis of lipid composition, phyto plankton was collected by filtering 5 to 71 of seawater sampled from the layer of maximum chlorophyll a through glass fibre filters (type gf/ c) which had previously been washed with chloroform : methanol (2 : 1, v/v). the filters con taining phytoplankton were stored in glass vials filled with chloroform : methanol (2 : 1, v/v) and stored at 15°c until analysed further. carbon fixation incubations only samples taken from stations 1 and 2 were used for the study of carbon fixation. samples of seawater taken from the deep chlorophyll a maximum were placed in glass bottles and nahi4co3 (56mci mmol-i) added at a con centration of 250 kci i ' . for time course experi ments, 2 1 of seawater was incubated at 95 pmol m ? s l and 0.5"c. aliquots of 200 ml were taken at each required time point. in experiments on the effects of variation in temperature and light, 100 ml of seawater was used in each incubation. incubations were carried out for 12 hours in tem perature-controlled incubators with artificial illumination supplied by fluorescent daylight tubes. samples of seawater were subjected to different light intensities by surrounding the incu bation bottles with nylon mesh of different mesh sizes. light was measured inside the bottles using the probe of the quantum meter. samples were equilibrated at the required temperature for 1 hour before the addition of nahi4co3. at the end of incubation time, 10% of total sample volume was filtered through a gf/c filter and a further 100ml of previously-filtered sea water passed through the same filter. the filter was transferred to a scintillation vial and stored at -15°c for the later determination of total carbon fixation by scintillation counting after the addition of scintillant fluid. the remainder of each sample was collected onto another filter and stored in 7 ml chloroform : methanol ( 2 : 1, v/v) at -15°c for later analysis of the distribution of radioactivity in the end products of photosyn thesis. in the laboratory, cells retained on glass fibre filters were fractionated into chloroform soluble (lipid), methanol-water soluble (low molecular weight material), hot trichloroacetic acid soluble (polysaccharide) and hot trichloroacetic acid insoluble (protein) fractions according to the pro cedure of rivkin (1985). aliquots of the fractions were transferred to polythene scintillation vials, dried and resuspended in scintillation fluid prior to measurement of radioactivity content by liquid scintillation spectrophotometry. lipid analysis for the analysis of lipid, filters stored in chloroform : methanol ( 2 : 1, v/v) were macerated in more of the same solvent system and filtered. the filtrate was shaken with one quarter its vol ume of 0.88% kci. after centrifugation, the aqueous layer was discarded and the organic sol vent evaporated to yield a lipid extract which was desiccated under vacuum and redissolved in ch1oroform:methanol (2: 1, v/v). the techniques employed for the separation and quantitation of lipid classes have been described elsewhere as have the procedures used for the analysis of fatty acid composition (olsen & henderson 1989; henderson & mackinlay 1989). lipid composition of phytoplankton 23 1 the distribution of fixed carbon in lipid fractions was measured by separating lipid classes by thin layer chromatography and measuring directly the radioactivity contained in bands of adsorbant by standard scintillation techniques. results characteristics of sampling stations at the three stations examined, the chlorophyll a maximum occurred at a depth of 40 to 50 m and was located within a layer of cold water which occurred at all stations between 20 and 60m. the highest chlorophyll a concentrations were observed at station 3 (table 1). the colonial haptophyte phaeocystis pouchetii and the colonial chrysophyte dinobryon pel lucidum always dominated the phytoplankton from the chlorophyll a deep maximum. of the two species, p. pouchetii was the most abundant at all three stations but especially at station 3 where it comprised some 70% of the total phyto plankton present in terms of cell numbers. very small numbers of the diatoms thalassiosiru nor denskioeldii and chaetoceros compressus were also observed in the samples from all three stations. at station 1 the irradiance at 4 0 m when the phytoplankton was sampled was 42 p o l m-ls-', corresponding to 6.5% of the irradiance measured just beneath the surface of the water. the lowest temperature of water sampled occurred at station 2. lipid composition of phytoplankton samples the amounts of total lipid extracted from the phytoplankton samples were too small to be esti table 1 . characteristics of water sampling stations. mated gravimetrically. general similarities were notable between stations 1 and 2 in the relative abundance of the lipid classes in lipid of phyto plankton (table 2). under the analytical con ditions employed, lipid-soluble pigments were the most abundant component of the lipid extracted accounting for 38.9% and 29.4%, respectively, of the total lipid at stations 1 and 2. of the total lipid extracted from phytoplankton at station 3, 17.7% was pigmented material and 19.5% was in the form of triacylglycerols, the major lipid class at this station. excluding pigments, neutral lipids comprised a larger proportion than polar lipids of the total lipid from the phytoplankton at all three stations. triacylglycerols were always the pre dominant lipid class. in addition to triacyl glycerols, sterol esters were also a major neutral lipid and comprised approximately 10% of the lipid in phytoplankton from each station. the proportion of monogalactosyldiacylgly cerol in each lipid extract was more than twice that of the other two galactolipids present, diga lactosyldiacylglycerol and sulphoquinovosyldia cylglycerol. the proportion of galactolipids was highest in phytoplankton from station 3 (7.8% of total lipid) but at all stations the level of these lipids was lower than that of phospholipids which accounted for 14.9%, 18.2% and 23.8% of the total lipid in phytoplankton taken from stations 1 , 2, and 3. phosphatidylcholine was the pre dominant phospholipid class in each case. the fatty acid compositions of the total lipid from phytoplankton at all three stations were generally similar (table 3). 16:o was the most abundant fatty acid, accounting for 25 to 30% of the total fatty acids. in all samples the proportions of saturated fatty acids decreased in the order 16:0,18:0,14:0,15:0,17:0. taken together, these fatty acids comprised around half the total fatty acids present in the lipid from the phytoplankton station 1 station 2 station 3 location depth sampled (m) temperature ("c) chlorophyll a (pg i ' ) ' phaeophytin (pg i ' ) species composition (% phaeocystis: % dinobryon) 75"46'n 34"48'e 40 0.19 0.48 0.78 60:40 75%" 28"24'e 50 -0.82 1.19 1.49 58 : 42 76'04" 33"18'e 40 -0.36 1.29 0.98 71:29 232 r . j . henderson, r . e . olsen & h. c. eilertseti table 2 . lipid composition ( q total lipid) of phytoplankton from different stations at each station. t h e levels of the monoenes (18:l(n-9) and 16:l(n-7) were very similar in all three lipid samples, accounting for some 13% and 9 9 of the fatty acids in each. lipid class station 1 station 2 station 3 hydrocarbons 6.6 8.2 5.8 triacylglycerols 12.8 11.3 19.5 free fatty acids 6.0 8.6 9.2 pigment 38.9 29.4 11.7 mgdg 4 2 5.2 5.5 pe 4 . 7 4.6 5.3 psipi 2 7 3.3 5.1 pc 4 , 9 6 . 1 7.9 abbreviations: pag. partial acylglycerols; m g d g . mono galactosyldiacylglycerols. d g d g . digalactosyldiacylglycerols: sl. sulphoquinovosyldiacylglyercol: pe. phosphatidylethan olamine: pg. phosphatidylglycerol. cl. cardiolipin: ps. phos phatidylsenne: pi. phosphatidyinositol; pc. phosphattdyl choline. steryl esters 10 4 10.4 9. i sterols/pag 5 5 6.8 7.3 dgdg/sl 0.9 1 .6 2.3 pg/cl 2 6 4 2 5 . 5 14:o 1 5 : o 16:o 16: 1 (n-917) 16:2 16: 3 16:4 17.0 18: 0 18: 1 (n-9) 18: 1 (n-7) 1 8 : 2 (n-6) 18:3 (n-6) 18: 3 (n-3) 1 8 : 4 (n-3) 1 8 : 5 (n-3)!20:0 20: 1 (n-9) 2 0 : 4 (17-6) ?0:4 (n-3) 2 0 : 5 (n-3) 7 3 . i 2 2 . 5 (n-3) 2 2 : h in-3) 2 4 . 1 in-9) unknouns totdl satb. total monos total pufa _ t h e lipid from station 1 phytoplankton had a higher content of polyunsaturated fatty acids ( p u f a ) than that from the other two stations, due mainly to the fact that 20:5(n-3) accounted for 1 . 4 % of the fatty acids in this lipid but only 2.4% and 3.9% in those from stations 2 and 3. the level of 22:6(n-3) was also higher in the sample from station 1 than from the other two stations. in all samples the level of 18:4(n-3) exceeded that of 18:3(n-3). overall the (n-3) p u f a predominated over the (n-6) p u f a . 18:2(n-6) comprised less than 4%, and 20:4(n-6) less than 1 % . of t h e total fatty acids in all samples. lipid of phytoplankton from station 2 contained the lowest proportion of p u f a , 15.5% of the total fatty acids. carbon fixation by phytoplankton the rate of total carbon fixation was slightly table 3 . fauty acid composition ( w t '3) of total lipid. higher at station 1 than at station 2 (fig. 1). differences were also observed in t h e incor fatty acid station 1 station 2 station 3 poration pattern of fixed carbon into different cell fractions in relation t o incubation time. a t station 3 3 1 i ) 7 2 1 polysaccharides were the most radioactively 58 6.7 5.5 25 4 8 4 0 3 21 7 6 13 2 2 6 3 0 0 4 1 2 3 2 2 9 0 3 0 3 10 4 0 7 7 4 i 4 29.6 9 9 u.4 i ? 2 6 10.3 13.3 2 . 1 ? . i 0.5 1.6 2 0 3 3 (1 5 0.7 0 2 2 4 0 4 4 3 1 . 4 _ _ 30 z 7 9 0 3 0 9 03 2 0 1 6 13 9 19 3 2 0 7 1 7 31 3 5 0 6 0 6 i i 3 9 o x 6 2 03 0 9 labelled components after 2 hours and contained 33% of the total fixed carbon. in contrast, this fraction contained only 19% of the total carbon fixed in the same time a t station 2. low molecular weight ( l m w ) compounds showed the greatest labelling over 2 hours at station 2. a t station 1 the incorporation rates of carbon into protein and lipid were similar. after 24 hours these fractions together contained two-thirds of the fixed carbon. at station 2, the incorporation rates into protein and lipid were also linear and similar. t h e rates of carbon assimilation into lmw material and polysaccharides were less than those into protein and lipid by phytoplankton from both stations, although the differences were less pronounced at station 2. protein, lipid, l m w material, and polysaccharides contained 35.2%, 33.5%, 18.1 %, and 13.2% of the total carbon assimilated by phytoplankton from station 1 over 24 hours. t h e . ~ . 4 7 . 0 56 3 5 2 u corresponding values for phytoplankton from sta 2 5 1 26.8 2s i tion 2 were 3 0 . 9 5 ' ~ ~ 27.396, 26.0%, and 15.8%. within the total lipid, phospholipids always contained less fixed carbon than neutral lipids or galactolipids at both stations (fig. 2) and gen 2 2 . 0 26 2 is 5 s a t s . = saturates. monos. = monounsaturates, pufa = poly. unsaturated $aft! acids. lipid composition of phytoplankton 233 1.5 1 .o 0.5 c '= 0.0 0.50 j 0.251 ,.& i@@ 0.00' . ' ' ' . ' . ' 0 6 1 2 1 8 2 4 time (hours) fig. 1 . assimilation of carbon into end products of photo synthesis by water samples from layer of maximum chlorophyll (i content. note difference in scales used for stations 1 and 2. values are means of duplicate incubations: 0-c = lipid; 0-0 = protein; c. = polysaccharides; 0 0 = l.m.w. compounds. erally accounted for 16 to 26% of the carbon assimilated into lipid. differences were observed between the two stations in the relative dis tribution of fixed carbon between the neutral lipid and galactolipid fractions. with phytoplankton from both stations, however, the proportion of fixed carbon in galactolipids was least after 24 hours and neutral lipid contained the most fixed carbon after this time, accounting for 40% of the carbon fixed into lipid. in general, no great differences were observed in the amount of carbon fixed in relation to light intensity or temperature over 12 h (table 4). at station 1, a slight trend was apparent whereby the amount of carbon fixed at 0.5 and 8.5 fmol m-2 s-i increased as temperature increased. this pattern was not apparent with phytoplankton from station 2. a high degree of variation was observed between replicate incubations in the distribution of assimilated carbon in cellular fractions (figs. " t 40 2 30 3 20 q . c c 0 c 10 ' 5 .0 . % c c c ' 50 1 ""i 0 stn2 a9 40 30 20 10 0 2 4 8 12 24 time (hours) fig. 2. distribution of carbon fixed into total lipid within lipid fractions. values are means of duplicate incubations. 3.and 4). at the lowest temperature examined (-1s"c), lmw material contained the highest, and lipid the second highest, proportion of carbon assimilated at 0.5 and 8.5 pmol m-*s-' by phyto plankton from both stations. at the same light and a temperature of o s t , lmw material also table 4. efects of temperature and light intensity on total carbon fixation. temp light intensity station 1 station 2 "c p o l n i 2 s c 1 fgc(pgchla)-' b-' -1.5 0.5 8.5 -0.5 0.5 8.5 95.2 0.5 0.5 8.5 95.2 4.5 8.5 0.16 ? 0.03 0.23 5 0.04 n.d. n.d. n.d. 0.27 2 0.01 2.57 2 1.63 0.48 2 0.14 0.34 2 0.13 0.52 2 0.02 0.64 t 0.13 0.40 2 0.17 0.66 2 0.17 0.60 f 0.09 n.d. n.d. n.d. 0.68 5 0.01 n.d. = not determined. values are means 2 s.d. of three incu bations. 234 r. j. henderson. r . e . olsen & h . c . eilertsen m llpd in incubations with water from stations 1 and prote'n 2 at 0.5 and -0.5"c, respectively, t h e distribution patterns observed at 95 pmol m-'s-' were notably different from those of t h e same temperature but lower irradiance in that t h e lmw compounds contained less fixed carbon. protein also con tained more fixed carbon than polysaccharides a t the higher light intensity. although the per centage fixed into lipid decreased with increasing light intensity at 0.5"c at station 1, the change po'ysvc 601 4.5-c w t t 0 5 0 5 9 5 2 light intensity (pmol 1-6';') flg 3 effects of light and temperature o n the distribution of carbon assimilated by waters sampled at station 1 into end producis of photos)nlhesis values are means of 3 incubations vertical bars represent s d contained most of the carbon fixed by phy toplankton from station 1 and the distribution pattern was generally similar to that observed at -1.5"c. in contrast, the distribution pattern observed with phytoplankton from station 2 at 0 . 5 t a n d 0 . 5 a n d 8 . 5 p o l m ? s ' w a s n o t c o m parable with that seen with the same phy toplankton at 1.5"c. -1.5-c 7 50 l v d e protein t polysacc 40 30 20 10 0 &)i 4.5-c 40 "1 0 5 8 5 9 5 2 -2 -1 light intensity (pmol rn s ) fig. 4 . effects of light and temperature on the distribution of carbon assimilated by waters sampled at station 2 into end products of photosynthesis. values are means of 3 incubations and vertical bars represent s.d. lipid composition of phytoplankton 235 photosynthesis (bird & kalff 1987), the overall lipid composition of this species may be less influ enced by lipids associated with chloroplasts as that of purely photosynthetic species. in comparison with phytoplankton material including phaeocystis sp. sampled from temperate regions (claustre et al. 1990; kattner et al. 1983), the lipids from the barents sea phytoplankton which were analysed in this study contained higher levels of polyunsaturated fatty acids. this is particularly noticeable when it is considered that most of the lipid actually consisted of tri acylglycerols, a situation which usually confers a low degree of unsaturation upon the total lipid (piorreck et al. 1984). although most fatty acids found in the total lipid in the present study also occurred in previous analyses of a surface slick of p . ,pouchetii from arctic/boreal waters (sargent et al. 1985) and in phaeocystis sp. in the irish sea (claustre et al. 1990), the overall fatty acid profile was not very similar to either. in particular only 4% of the total fatty acids in the phaeocystis sp. from the irish sea were polyunsaturated (claustre et al. 1990) in comparison with over 50% in that from northern norwegian waters (sargent et al. 1985) and around 20% in the phytoplankton ana lysed here. apart from the fact that the fatty acids of d. pellucidurn also contributed to the overall fatty acid composition in this study, differences in the stage of growth as well as environmental parameters are likely to influence the fatty acid composition of phaeocystis species. thus, no definite conclusions can be drawn from the present data about the fatty acid composition of phytoplankton adapted to the low temperatures of arctic waters in comparison with the same species from more temperate waters. the detailed fatty acid composition of the lipid classes of phy toplankton from arctic waters has not been exam ined, mainly due as in the present study to the collection of insufficient material. further analy ses of the lipid composition of arctic phyto plankton may reveal specific adaptations to their habitat and also yield information on seasonal changes in their value as food for zooplankton. the lowering of temperature in photosynthetic algae generally leads to an increase in the pro portion of polyunsaturated fatty acids in the lipid (ackman et al. 1968; henderson & mackinlay, 1989). however, it is to be noted that polyun saturated fatty acids are not major components of any class of lipids on sea ice diatoms (nichols et al. 1986). an increased content of polyun was not statistically significant and no such trend was observed in relation to light intensity at sta 'tion 2 at -0s"c. when the distribution patterns of fixed carbon at 8.5 pmol m-2s-1 were compared over three different temperatures, the most notable effect was that the proportion recovered in protein was highest at 4.5"c at both stations. correspond ingly, lmw material contained least assimilated carbon at this temperature. in contrast to the situation at 4.5"c, lipid accounted for a higher proportion of assimilated carbon than protein at 1.5"c. discussion phaeocystis pouchetii and dinobryon pellucidurn, particularly the former, are regular members of the phytoplankton community in the atlantic and qrctic waters of the barents sea during spring and summer (eilertsen 1989; eilertsen et al. 1989a, b, c). although the lipid composition of p. pouchetii has been examined in phytoplankton sampled from non-arctic waters (claustre et al. 1990; sargent et al. 1985), it has not been examined in this species taken from the barents sea, and as far as we are aware no data are available on the lipids of d . pellucidurn. the lipid compositions reported here are those of the lipid extracted from the total assemblage of phytoplankton in the waters sampled. although p . pouchetii dominated at all three sta tions in terms of cell numbers, it cannot be assumed that the overall lipid composition mainly reflects the lipid of this species since it is not known whether the two principal species have similar lipid contents. neutral lipid classes pre dominated in the lipid of the phytoplankton exam ined. such lipid classes have also been shown to be more abundant than phospholipids in the lipid of sea ice diatoms in the antarctic (nichols et al. 1986). it is known that the proportion of tri acylglycerols, the major neutral lipid found here, increases in batch cultured algae during nutrient depletion and consequently the amount of satu rated fatty acids present also increases (piorreck et al. 1984; mortensen et al. 1988). the lipid composition of natural populations is also likely to change with the growth stage. consequently the pattern of dietary fatty acids available to herbivorous predators is not constant. since d . pellucidurn is capable of phagotrophy as well as 236 r . j . h e n d e r s o n . r . e . o l s e n & h . c. eilertsen saturated fatty acids in comparison with phyto plankton from temperate waters may not be a general adaptation to low environmental tem perature in polar phytoplankton. the proportion of total fixed carbon incor porated into lipid never exceeded 30% under any of the conditions employed in this study. this is in agreement with the corresponding value reported for phytoplankton sampled from many locations, including the arctic waters of eastern canada (li & platt 1982), northern norwegian fjords (sargent et al. 1985). tropical waters (morris e t al. 1981), eutrophic scandinavian lakes (jensen 1985) and temperate waters (harding et al. 1985). t h e incorporation of 80% of fixed carbon into lipid by phytoplankton from the antarctic ocean (smith & morris 1980a, b) has been attributed to low temperature coupled with low irradiance. t h e present results imply that other factors must also be necessary for enhanced carbon assimilation into lipid by arctic phytoplankton. it is well known that the antarctic and arctic waters differ in many respects, including post bloom nutrient levels (sakshaug & holm-hansen 1984). previous studies o n distribution of fixed carbon in photosynthesis end products have only con sidered total lipid. this study shows that within the lipids of the phytoplankton from the barents sea most of the assimilated carbon is located in neutral and galactolipids. t h e lipid contained insufficient radioactivity t o permit the detailed analysis of the distribution of fixed carbon in specific lipid classes and component fatty acids. galactolipids contained a higher proportion of the carbon than expected on the basis of mass. it can be expected that. as well as the fatty acid moieties, the glyceryl and galactosyl moieties of acylglycerols and galactolipids. respectively, con tained fixed carbon. t h e distribution pattern of assimilated carbon between the moieties, and the effect of variations in temperature and irradiance on it, could not b e determined in the present study d u e to the lack of sufficient incorporated radioactivity. although no great differences were notable in the proportion fixed into lipid in response t o different incubation temperatures and irradiances. unseen changes may have occurred in the distribution of carbon between the lipid classes and between the component portions of the actual lipid classes. changes may also have occurred in the pattern of fatty acids synthesised. for example, the specific incorporation of radio activity into p u f a increases as growth tem perature decreases in a t least o n e species of marine algae in batch culture (henderson & sar gent 1989). in the present study the phytoplankton were subjected to sudden changes in temperature and irradiance. since adaptive mechanisms are dynamic processes (mortain-bertrand et al. 1988), longer incubation times than those employed here might be required before signifi cant changes a r e observed in the assimilation of carbon into specific e n d products. further studies are necessary to examine in detail lipid synthesis in arctic phytoplankton in relation to t h e natural environmental parameters. acknowledgemenrs. r . j . henderson thanks the norwegian fisheries research council and the norwegian research pro gram for marine arctic ecology (pro mare) for allowing his participation in the research cruise. references ackman. r. g . . toeher. c . s. & mclachlan, j . 1968: marine phytoplankter fatty acids. 1. fish. res. bd. can. 25, 1603 1620. bird. d. f. & kalff. j . 1987: algal phagotrophy: regulating factors and importance relative to photosynthesis in dino b n o n (chrysophyceae). limnol. oceonogr. 32. 277-284. claustre. h . . poulet. s. a , . williams, r . , marty. j . c . . coornbs. s . . ben mlih, f.. hapette. a. m. & martin jezequel. v 1990: a biochemical investigation of a phaeo c w f b sp bloom in the irish sea. 1. mar. biol. ass. u . k . 70. 197-207 eilertsen. h . c. 1989: phaeocystis pouchetii (harlot) lagerheim. a key species i n arctic marine ecosystems: life history and physiology. rapp. p . o . riun. cons. inr. explor. mer 18%. 131. eilertsen. h. c.. taasen. j . p. & weslawski, j . m. 1989a: phytoplankton studies in the fjords of west spitsbergen: physical environment and production in spring and summer. j. plankron res. 1 1 . 1245-1260. eilertsen. h. c . . tande, k. s . & hegseth. e. n . 1989b: poten tial of herbivorous copepods for regulating the spring phy toplankton bloom in the barents sea. rapp. p.-o. reun. c o n s . inr. explor. mer 188. 154-163. eilertsen. h. c.. tande. k. s. & taasen. j . p. 1 9 8 9 ~ : vertical distribution of primary production and grazing by calanus glacialis jaschnov and c. hvperboreus kroyer in arctic waters (barents sea). polar biol. 9, 253-260. harding. l. w.. meeson. b. w.. fisher. t . r . 1985: patterns of photosynthetic carbon metabolism in light-limited phyto plankton. mar. biol. 89. 121-133. hansen. b.. berggreen. u . c.. tande, k. s.. eilertsen, h . c . 1989. post-bloom grazing by calanus glociolis. c. f i n marchicus and c. hvperboreus in the region of the polar front. barents sea mar. b i d . 104. 5-14. harrison. w. g. & platt. t . 1986: photosynthesis-irradiance lipid composition of phytoplankton 237 relationships in polar and temperate phytoplankton popu lations. polar biol. 5 . 153-164. henderson, r. j. & mackinlay. e. e. 1989: effect of tem perature on lipid composition of the marine cryptomonad chroomanas salina. phytochemistry 28, 294f2948. henderson, r . j . & sargent. j. r. 1989: lipid composition and biosynthesis in ageing cultures of the marine cryptomonad chroomonas salina. phytochemistry 28, 1355-1361. jensen. l. m. 1985: 'clabclling patterns of phytoplankton: specific activity of different product pools. 1. plankton res. 7 , 643-652. kattner, g . . gercken. g . . hammer, k. d. 1983: development of lipids during a spring plankton bloom in the northern north sea i particulate fatty acids. mar. chem. 1 4 , 149-162. li, w. k. & platt. t. 1982: distribution of carbon among photosynthetic end-products in phytoplankton of the eastern canadian arctic. 1. phycol. 18. 466471. morris, i . , smith. a. e. & glover, h. e . 1981: products of photosynthesis in phytoplankton off the orinoco river and in the carribbean sea. limnol. oceanogr. 26, 10341044. mortain-bertrand. a , , descolas-gros. c. & jupin. h. 1988: growth. photosynthesis and carbon metabolism in the tem perate marine diatom skeletonema costaturn adapted to low temperature and low photon-flux density. mar. biol. 100. 135-141. mortensen, s. h.. borsheim, k. y., rainuzzo, j . r. & knutsen, g. 1988: fatty acid and elemental composition of the marine diatom choetoceros gracilis schutt. effects of silicate dep rivation, temperature and light intensity. j. exp. mar. b i d . ecol. 122, 173-185. nichols, p. d., palmisano, a,. smith. g . a . & white, d. c. 1986: lipids of the antarctic sea ice diatom nitzschia cylindrus. phytochemistry 25, 164s1653. olsen, r. e. & henderson, r . j. 1989: the rapid analysis of neutral and polar marine lipids using double-development hptlc and scanning densitometry. j. exp. mar. biol. ecol. 129, 189-197. palmisano, a . c.. soohoo. j . b., soohoo, s. l., kohmeier. s. t., craft, l. l. & sullivan. c . w . 1986: photoadaptation in phaeocystis pouchetii advected beneath annual sea ice in mcmurdo sound antarctica. j. plankton res. 8 . 891-906. plorreck, m . , baasch, k.-h. & pohl, p. 1984: biomass produc tion. total protein, chlorophylls, lipids and fatty acids of freshwater green and blue-green algae under different nitro gen regimes. phytochemistry 23, 207-216. rivkin, r. b. 1985: carbon-14 labelling patterns of individual marine phytoplankton from natural populations. mar. biol. 89, 135-142. sakshaug, e. & holm-hansen, 0. 1984: factors governing pelagicproduction in polar oceans. pp. 1-18 in holm-hansen. o., bolis. l. & gilles. r. (eds.): marine phytoplankton and producriuiry. springer verlag. berlin. sargent. j . r., eilertsen, h . c., falk-petersen. s. & taasen, j . p. 1985: carbon assimilation and lipid production in phyto plankton in northern norwegian fjords. mar. biol. 85. 109 116. smith, a . e . & morris, i. 1980a: pathways of carbon assimi lation in phytoplankton from the antarctic ocean. limnol. oceanogr. 25, 865-872. smith. a. e . & morris, 1. 1980b: synthesis of lipid during photosynthesis by phytoplankton of the southern ocean. science 207, 197-199. fichefet.indd 91fichefet et al. 2003: polar research 22(1), 91–98 microwave-derived time series of sea ice concen tration (the percentage of ice-covered oceanic area) are now among the longest continuous satellite-derived geophysical records, spanning about 25 years. analyses of these records indicate that the ice area in the northern hemisphere (southern hemisphere) has shrunk (increased) at an annual mean rate of ~3 % (~1.5 %) per decade with strong interannual var i ability since the late 1970s (bjørgo et al. 1997; cavalieri et al. 1997; parkinson et al. 1999; comiso & steffen 2001). regarding the longer-term variability, vinje’s study (2001), based on in situ data collected in the nordic seas, suggests that the extent of ice in this region during april has undergone a reduc tion of ~33 % over the past 135 years against a background of pronounced decadal variations. analysis of another historical data set covering the whole arctic (updated from chapman & walsh 1993) has revealed that the spring and summer decreases (which are largely responsible for the overall negative trend in arctic sea ice area during the satellite observing era [parkinson et al. 1999]) were present during the entire second half of the 20th century and that there has been only a slight and uncertain downward trend in autumn a hindcast simulation of arctic and antarctic sea ice variability, 1955−2001 thierry fichefet, hugues goosse & miguel angel morales maqueda a hindcast simulation of the arctic and antarctic sea ice variability during 1955–2001 has been performed with a global, coarse resolution ice–ocean model driven by the national centers for environmental prediction / national center for atmospheric research reanalysis daily surface air temperatures and winds. both the mean state and variability of the ice packs over the satellite observing period are reasonably well reproduced by the model. over the 47-year period, the simulated ice area (defi ned as the total ice-covered oceanic area) in each hemisphere experiences large decadal variability together with a decreasing trend of ~1 % per decade. in the southern hemisphere, this trend is mostly caused by an abrupt retreat of the ice cover during the second half of the 1970s and the beginning of the 1980s. the modelled ice volume also exhibits pronounced decadal variability, especially in the northern hemisphere. besides these fl uctu ations, we detected a downward trend in arctic ice volume of 1.8 % per decade and an upward trend in antarctic ice volume of 1.5 % per decade. however, caution must be exercised when interpreting these trends because of the shortness of the simulation and the strong decadal variations. furthermore, sensitivity experiments have revealed that the trend in antarctic ice volume is model-dependent. t. fichefet & h. goosse, institut d’astronomie et de géophysique georges lemaître, université catholique de louvain, chemin du cyclotron 2, b-1348 louvain-la-neuve, belgium, fi chefet@astr.ucl.ac.be; m. a. morales maqueda, potsdam-institut für klimafolgenforschung, telegrafenberg c4, postfach 601203, d14412 potsdam, germany. 92 a hindcast simulation of arctic and antarctic sea ice variability and winter since about 1970 (folland et al. 2001). as for the antarctic, de la mare (1997) inferred from whaling records that the summer sea ice edge has moved southwards by 2.8° of latitude between the mid-1950s and the early 1970s. this suggests a decline in the area covered by sea ice of some 25 %. the indirect nature of the reconstruction, however, makes this conclusion very uncertain (ackley et al. 2003). another important variable characterizing the state of a sea ice pack is its volume, which can be determined from the ice thickness distribution. our knowledge of sea ice thickness in the northern hemisphere (nh) comes mainly from upward sonar profi ling by submarines. rothrock et al. (1999) compared ice draft data acquired by the scientifi c ice expeditions (scicex) programme in 1993, 1996 and 1997 with data from six cruises during the period 1958–1976. they found a decrease in the mean ice draft at the end of the melt season of about 1.3 m (i.e. 40 %) in most of the deep-water areas of the arctic ocean. comparing data from single cruises in 1996 and 1976 from fram strait to the north pole, wadhams & davis (2000) reported a strikingly similar reduction in ice draft. in contrast, ice draft data collected during six submarine cruises from alaska to the north pole in 1991–97 exhibit almost no change (winsor 2001). from nine cruises from 1976 through 1994 on the alaska-to-north pole section, tucker et al. (2001) found an abrupt thinning between the mid-1980s and early 1990s. no similar trend was observed, however, near the north pole. very recently, a detailed analysis of submarine and modelled ice thicknesses (holloway & sou 2002) has demonstrated that ice motion and high interannual variability make inference of trends from sonar transect data ambiguous. thus, the available sonar data are insuffi cient to resolve the variability of the arctic ice thickness. the situation is even worse in the southern hemisphere (sh). so far there have been very few systematic measurements of sea ice thickness in the southern ocean and the available records are rather short (e.g. harms et al. 2001), to the point that the broad spatial and seasonal climatology of antarctic ice thickness is not well known. in the present work, a global, coarse resolution ice–ocean model is used to document the variability of the arctic and antarctic sea ice during the 47-year period 1955–2001. daily data of sur face air temperature and wind are utilized to produce the year-to-year variations of the ice packs. we focus on analysing the simulated variability of the ice area and volume in both hemispheres. we also evaluate the model performance by comparing ice area anomalies from the last two decades of this hindcast simulation with those derived from satellite measurements. experiments of this type have been carried out with regional models of the arctic or antarctic sea ice–ocean system (e.g. polyakov & johnson 2000; zhang et al. 2000; beckmann & timmermann 2001; holloway & sou 2002). however, to our knowledge, this is the fi rst time that an ice–ocean model designed for climate studies is utilized for investigating the changes of both the arctic and antarctic ice covers in the recent past. the model, forcing and experimental design the model used here is based on that of goosse et al. (2000) and fichefet et al. (2003). it is made up of a primitive-equation, free-surface ocean general circulation model coupled to a thermodynamic–dynamic sea ice model with viscous-plastic rheology. the horizontal resolution is 1.5° × 1.5°, and there are 30 unequally spaced vertical levels in the ocean. the following modifi cations have been made to the original model. first, a truncated elliptical yield curve and the so-called replacement closure (e.g. geiger et al. 1998) have been introduced in the formulation of the ice rheology to prevent any tensile stress and to guarantee energy conser vation. second, a more computationally effi cient numerical method for solving the ice momentum equation (zhang & hibler 1997) has been imple mented. third, in fichefet et al. (2003), an ad hoc redistribution of the heat fl ux through open water was applied to ensure that thermo dynamic closure of leads did not occur. this artefact has been removed. the model now includes a physically-based formulation of the open ing of leads by shearing deformation (stern et al. 1995) together with a parameterization of the col lec tion thick ness of ice in leads based on that of biggs et al. (2000). the model is driven by daily surface air temperatures and winds from the national centers for environmental prediction / national center for atmospheric research (ncep/ncar) reanalysis project for the period 1948–2001 (kalnay et 93fichefet et al. 2003: polar research 22(1), 91–98 al. 1996). the ncep/ncar reanalysis data set is the longest global gridded atmospheric data set available today. unfortunately, it con tains a number of inaccuracies, artifi cial climate trends and even errors (e.g. hines et al. 2000; kistler et al. 2001) that must be borne in mind when interpreting the results of our simulation. the other atmospheric input fi elds consist of climat ological monthly surface relative humid ities (trenberth et al. 1989), cloud fractions (ber liand & strokina 1980) and precipitation rates (xie & arkin 1996). the surface fl uxes of heat and momentum are determined from these data by using empirical parameterizations (see fichefet et al. 2003 for details). evapor ation / sublimation is derived from the turbulent fl ux of latent heat. the freshwater infl ows from the largest rivers are prescribed according to the monthly climatology of grabs et al. (1996). for the smaller rivers, the annual run-off values of baumgartner & reichel (1975) are employed. in addition, a relaxation towards observed annual mean salinities (levitus 1982) is applied in the 10 m thick surface grid box with a time constant of 2 months. the simulation started from a quasiequilibrium state obtained under a monthly climatological forcing built from the above-mentioned data fi elds. the model was integrated over three 54-year cycles driven by forcing fi elds from 1948 to 2001. the results discussed below are those from the third cycle. the fi rst 7 years of this cycle are excluded from the analysis because sensitivity experiments to initial conditions showed that the ice characteristics during these years were notably affected by the forcing jump that occurred at the beginning of each cycle and because of the poor quality of the ncep/ncar reanalysis data during this period (kistler et al. 2001). results table 1 indicates that the model does fairly well in simulating the mean seasonal cycle of the sea ice area in both hemispheres. regarding the modelled ice volume, it oscillates in the nh between a maximum of 29.8 × 103 km3 in may and a minimum of 15.1 × 103 km3 in september, on average; it oscillates in the sh between a max imum of 12.2 × 103 km3 in october and a minimum of 1.6 × 103 km3 in february, on average. the time series of the monthly ice area anomalies produced by the model in both hemi spheres are illustrated in fig. 1. also shown in this fi gure are the monthly ice area anomalies derived from passive microwave measurements by using the bootstrap algorithm (comiso 2002). the simulated and observed anomalies were obtained by taking the monthly value for each individual month and subtracting the average value for that month over the period during which satellite data are available (november 1978–september 2001). the marked interannual variability seen in the data is relatively well captured by the model. in particular, thanks to the forcing, the model is capable of simulating the transition from a negative anomaly in arctic ice area in 1995 to a very large positive one in 1996. the abnormally low antarctic ice areal coverage observed during the second half of 1979 and the fi rst half of 1980 as well as the strong positive and negative anomalies in maximum antarctic ice area recorded in 1985 and 1986 are also well reproduced. however, one can see that the model signifi cantly underestimates the arctic ice area during 1979–1981. according to tartinville et al. (2002), this feature would mostly result from a warm bias in the ncep/ncar surface air temperatures during this period in the beaufort and laptev seas and in baffi n bay. in addition to this problem, the model has a tendency to exaggerate the negative ice area table 1. simulated and observed seasonal maximum and minimum sea ice areas in the northern and southern hemispheres averaged over the years 1978–2001. the observed values were derived from passive microwave measurements by applying the bootstrap algorithm (comiso 2002). nh sea ice area sh sea ice area march september february september model 14.1 × 106 km2 6.5 × 106 km2 1.4 × 106 km2 16.1 × 106 km2 observations 14.2 × 106 km2 6.2 × 106 km2 2.2 × 106 km2 15.8 × 106 km2 94 a hindcast simulation of arctic and antarctic sea ice variability anomalies observed since 1995 in the sh. despite these shortcomings, the correlation between the simulated and observed time series is 0.75 in the nh and 0.56 in the sh. on the other hand, the standard deviation of the modelled anomalies over the 22.9-year period of satellite data is 0.33 × 106 km2 in the nh and 0.44 × 106 km2 in the sh. these values are consistent with the observed ones (0.36 × 106 km2 and 0.35 × 106 km2, respectively), although slightly overestimated in the sh. at least two factors might be responsible for the weaker correlation noticed in the sh: (1) the lower accuracy of the ncep/ncar rean alysis data in this hemisphere (kistler et al. 2001) and (2) the more important role played in the sh by the deep ocean (which is not restored towards observations in our simulation and thus can depart significantly from reality) in con trolling the variability of the sea ice cover. a least squares regression analysis of the model results reveals a decrease of 13 650 ± 2900 km2 yr -1 in arctic ice area between november 1978 and september 2001. by contrast, no statistic ally sig nifi cant trend in antarctic ice area is detected. as for the bootstrap data, they show an overall decreasing trend of 32 500 ± 2600 km2 yr -1 in arctic ice area; they show an overall increasing trend of 15 350 ± 3050 km2 yr -1 in the antarctic ice area. it should be noted that the agreement between the simulated and observed trends improves substantially if one excludes from the analysis the years for which we have identifi ed sys tem atic problems (see above). furthermore, one should mention that there are substantial dif ferences in the satellite-derived sea fig. 1. time series of monthly ice area anomaly as simulated by the model (grey line) and as observed (dashed black line) for (a) the northern hemisphere and (b) the southern hemisphere. (a) nh (b) sh 95fichefet et al. 2003: polar research 22(1), 91–98 ice areas depending on which algorithm is used to retrieve the ice compactness from the passive microwave data (e.g. comiso et al. 1997; markus & cavalieri 2000). so, the model might actually do a better job than the comparison with the bootstrap data suggests. over the period 1955–2001, the simulated ice area decreases by 8300 ± 1000 km2 yr -1 (0.8 % per decade) in the nh and by 9200 ± 1500 km2 yr -1 (0.9 % per decade) in the sh. super imposed on these trends are pronounced decadal variations. in the sh, the overall negative trend is mainly due to an abrupt decline in ice area taking place during the second half of the 1970s and the beginning of the 1980s. actually, the mean ice area from 1982 to 2001 (after the decline) is 0.3 × 106 km2 lower than that from 1955 to 1976 (before the decline). this shrinkage is somewhat weaker than the one obtained by fichefet et al. (2003) (0.5 × 106 km2) with an earlier version of the model that runs over the period 1958–1999. one cannot rule out the possibility that the modelled decline is caused, at least partly, by a change in the observing systems utilized in the ncep/ncar reanalysis. such a change took place in 1979 when the global operational use of satellite soundings was introduced (kistler et al. 2001). however, it is noteworthy that the computed monthly ice area anomalies compare favourably with the observed ones during the last two months of 1978 (see fig. 1). furthermore, there is some observational evidence that the antarctic sea ice cover was more extensive in the mid-1970s than during recent decades (e.g. folland et al. 2001). according to (a) nh (b) sh fig. 2. time series of monthly ice volume anomaly as simulated by the model for (a) the northern hemisphere and (b) the southern hemisphere. 96 a hindcast simulation of arctic and antarctic sea ice variability fichefet et al. (2003), this retreat of the ice pack would be partly attributable to the strong weakening of the antarctic semi-annual oscillation observed since the mid-to-late 1970s in the real atmosphere and also present in the ncep/ncar reanalysis (e.g. van den broecke 1998). figure 2 displays the monthly ice volume anomalies simulated by the model in both hemispheres. as in fig. 1, the anomalies are relative to november 1978–september 2001. in the model nh, the ice volume experiences strong dec adal variability, with maxima around the years 1956, 1966, 1977 and 1987. large negative anomalies are visible in the early 1980s and since the mid1990s. over the entire period, there is a decreasing trend of 40.0 ± 5.2 km3 yr -1 (1.8 % per decade). this fi gure must, however, be taken with caution because of the relative shortness of the time series and the high amplitude decadal fl uctuations. all these results are consistent with those from other modelling studies (e.g. hilmer & lemke 2000; polyakov & johnson 2000; zhang et al. 2000; holloway & sou 2002; tartinville et al. 2002). from fig. 2 it can be seen that the modelled antarctic ice volume also exhibits decadal vari ability. however, the peak-to-trough changes are generally much weaker than the arctic ones. in addition to these oscillations, there is an overall increase in ice volume of 10.5 ± 1.5 km3 yr -1 (1.5 % per decade). this upward trend is mainly a consequence of the enhanced ice vol umes produced by the model from the mid-1980s onwards. this feature was not present in the simulation made by fichefet et al. (2003). sensitivity experiments performed with the cur rent version of the model have revealed that its occurrence depends on the formulation utilized for lead processes. in particular, the use of a parameterization for the collection thickness of new ice in leads that includes the effect of surface wind (biggs et al. 2000) seems to be of crucial importance. this will be explored more thoroughly in a forthcoming paper. conclusion a hindcast simulation has been conducted with a global, coarse resolution ice–ocean model forced with the ncep/ncar reanalysis daily surface air temperatures and winds in order to document the variability of the arctic and antarctic sea ice covers over the period 1955–2001. we stress that this simulation did not include the potential contribution from the hydrological cycle variability to the changes of sea ice on inter annual or longer time scales. the model does reasonably well in reproducing the mean state and variability of the arctic and antarctic sea ice areas over the satellite observing era, and this with the same set of para meter values for both hemispheres. several defi ciencies were identifi ed, however, such as too low ice areas in the nh during 1979–1981, too large negative ice area anomalies in the sh since 1995, and too weak and too thin an ice cover in the western weddell sea (see fichefet et al. 2003). most of them were partly attributed to inaccuracies in the atmospheric forcing fi elds. the simulation revealed decadal variations in ice area along with downward trends of about 1 % per decade in both hemispheres over the period 1955–2001. in the sh, this trend mainly results from a mean loss of ice cover of 0.3 × 106 km2 during the second half of the 1970s and the beginning of the 1980s. the marked weakening of the antarctic semi-annual oscillation observed since the mid-to-late 1970s in the real atmosphere and captured by the ncep/ncar reanalysis seem to contribute signifi cantly to this feature. nevertheless, part of the modelled decrease in ice area might be spurious and caused by the introduction in the ncep/ncar reanalysis of satellite sounding data in 1979. the computed ice volume also exhibits large decadal variability in both hemispheres. however, the amplitude of the fl uctuations appears much higher in the nh than in the sh. this is due to the fact that most of the antarctic ice melts away during summertime, while a large part of the arctic ice cover survives the summer melt, thus providing a memory at longer time scales. of particular interest in the nh are the very low values of ice volume simulated in the early 1980s and from the mid-1990s onwards. over the period 1955–2001, the ice volume decreases by 1.8 % per decade in the model nh and increases by 1.5 % per decade in the model sh. however, caution must be exercised when interpreting these trends because of the shortness of the time series and the strong decadal variations. furthermore, we have shown that the sh trend is highly dependent on the type of lead parameterization utilized. 97fichefet et al. 2003: polar research 22(1), 91–98 acknowledgements.—we wish to thank the two anonymous referees for their careful reading of the manuscript and constructive criticism. the ncep/ncar reanalysis data were provided by the national oceanic and atmospheric administration/cooperative institute for research in environ mental sciences climate diagnostics center, boul der, from their internet site at www.cdc.noaa.gov. the boot strap sea ice areas were obtained through the national snow and ice data center, university of colorado, boulder. t. fichefet is research associate with the belgian national fund for scientifi c research. this study was carried out as part of the second multiannual scientifi c support plan for a sustainable development policy (belgian state, prime minister’s services, federal offi ce for scientifi c, technical, and cultural affairs, contracts ev/10/7d and ev/10/9a), the concerted research action 097/02-208 (french community of belgium, department of education, research, and form ation), the frfc project 2.4556.99 (belgian national fund for scientifi c research), and the french project of operational oceanography mercator. support from each of these is gratefully acknowledged. references ackley, s., wadhams, p., comiso, j. c. & worby a. p. 2003: decadal decrease of antarctic sea ice extent inferred from whaling records revisited on the basis of historical and modern sea ice records. polar research 22, 19–25. baumgartner, a. & reichel, e. 1975: the world water balance. new york: elsevier. beckmann, a. & timmermann, r. 2001: circumpolar infl uences on the weddell sea: indication of an antarctic circum polar coastal wave. j. clim. 14, 3785–3792. berliand, m. e. & strokina, t. g. 1980: global distribution of the total amount of clouds. leningrad: hydro meteorological. biggs, n. r. t., maqueda, m. a. m. & willmott, a. j. 2000: polynya fl ux model solutions incorporating a para meterization for the consolidated new ice. j. fluid mech. 408, 179–204. bjørgo, e., johannessen, o. m. & miles, m. w. 1997: analysis of merged smmr–ssmi time series of arctic and antarctic sea ice parameters 1978–1995. geophys. res. lett. 24, 413–416. cavalieri, d. j., gloersen, p., parkinson, c. l., comiso, j. c. & zwally, h. j. 1997: observed hemispheric asymmetry in global sea ice changes. science 278, 1104–1106. chapman, w. l. & walsh, j. e. 1993: recent variations of sea ice and air temperature in high latitudes. bull. am. meteorol. soc. 74, 33–47. comiso, j. c. 2002: bootstrap sea ice concentrations from nimbus-7 smmr and dmsp ssm/i. boulder: national snow and ice data center. digital media. comiso, j. c., cavalieri, d. j., parkinson, c. l. & gloersen, p. 1997: passive microwave algorithms for sea ice concentra tion: a comparison of two techniques. remote sens. environ. 60, 357–384. comiso, j. c. & steffen, j. 2001: studies of antarctic sea ice concentrations from satellite data and their applications. j. geophys. res. 106(c12), 31 361–31 385. de la mare, w. k. 1997: abrupt mid-twentieth-century decline in antarctic sea-ice extent from whaling records. nature 389, 57–60. fichefet, t., tartinville, b. & goosse, h. 2003: antarctic sea ice variability during 1958–1999: a simulation with a global ice–ocean model. j. geophys. res. 108(c3), 3103. folland, c. k., karl, t. k., christy, j. r., clarke, r. a., gruza, g. v., jouzel, j., mann, m. e., oerlemans, j., salinger, m. j. & wang, s.-w. 2001: observed climate variability and change. in j. t. houghton et al. (eds.): climate change 2001: the scientifi c basis. contribution of working group i to the third assessment report of the inter governmental panel on climate change. pp. 99–181. cambridge: cambridge university press. geiger, a. g., hibler, w. d. iii & ackley, s. 1998: largescale sea ice drift and deformation: comparison between models and observations in the western weddell sea during 1992. j. geophys. res. 103(c10), 21 893–21 913. goosse, h., campin, j.-m., deleersnijder, e., fichefet, t., mathieu, p.-p., morales maqueda, m. a. & tartinville, b. 2000: description of the clio model, version 3.0. institut d’astronomie et de géophysique georges lemaître scientifi c report 2000/3. université catholique de louvain, louvain-la-neuve, belgium. grabs, w., de crouet, t. & pauler, j. 1996: freshwater fl uxes from continents into the world oceans based on the data of the global runoff data base. global runoff data centre report 10. koblenz. harms, s., fahrbach, e. & strass, v. h. 2001: sea ice transports in the weddell sea. j. geophys. res. 106(c5), 9057– 9073. hilmer, s. & lemke, p. 2000: on the decrease of arctic sea ice volume. geophys. res. lett. 27, 3751–3754. hines, k. m., bromwich, d. h. & marshal, g. j. 2000: artifi cial surface pressure trends in ncep–ncar reanalysis over the southern ocean and antarctica. j. clim. 13, 3940–3952. holloway, g. & sou, t. 2002: has arctic sea ice rapidly thinned? j. clim. 15, 1691–1701. kalnay, e., kanamitsu, m., kistler, r., collins, w., deaven, d., gandin, l., iredell, m., saha, s., white, g., woollen, j., zhu, y., chelliah, m., ebisuzaki, w., higgins, w., janowiak, j., mo, k. c., ropelewski, c., wang, j., leetmaa, a., reynolds, r., jenne, r. & joseph, d. 1996: the ncep/ ncar 40-year reanalysis project. bull. am. meteorol. soc. 77, 437–470. kistler, r., kalnay, e., collins, w., saha, s., white, g., wool len, j., chelliah, m., ebisuzaki, w., kanamitsu, m., kousky, v., van den dool, h., jenne, r. & fiorino, m. 2001: the ncep–ncar 50-year reanalysis: monthly means cd-rom and documentation. bull. am. meteorol. soc. 82, 247–267. levitus, s. 1982: climatological atlas of the world ocean. noaa prof. pap. 13. washington, d.c. markus, t. & cavalieri, d. j. 2000: an enhancement of the nasa team sea ice algorithm. ieee trans. geosci. remote sens. 38, 1387–1398. parkinson, c. l., cavalieri, d. j., gloersen, p., zwally, h. j. & comiso, j. c. 1999: arctic sea ice extents, areas, and trends, 1978–1996. j. geophys. res. 104(c9), 20 837–20 856. polyakov, i. v. & johnson, m. a. 2000: arctic decadal and inter decadal variability. geophys. res. lett. 27, 4097– 4100. rothrock, d. a., yu, y. & maykut, g. a. 1999: thinning of the arctic sea-ice cover. geophys. res. lett. 26, 3469– 98 a hindcast simulation of arctic and antarctic sea ice variability 3472. stern, h. l., rothrock, d. a. & kwok, r. 1995: open water production in arctic sea ice: satellite measurements and model parameterizations. j. geophys. res. 100(c10), 20 601–20 612. tartinville, b., cavanié, a., ezraty, r. & fichefet, t. 2002: arctic multiyear ice coverage: a model study. institut d’astronomie et de géophysique georges lemaître scientifi c report 2002/1. université catholique de louvain, louvain-la-neuve, belgium. trenberth, k. e., olson, j. g. & large, w. g. 1989: a global ocean wind stress climatology based on the ecmwf analyses. national center for atmospheric research technical note 338+str. boulder, co. tucker, w. b. iii, weatherly, j. w., eppler, d. t., farmer, l. d. & bentley, d. l. 2001: evidence for rapid thinning of sea ice in the western arctic ocean at the end of the 1980s. geophys. res. lett. 28, 2851–2854. van den broecke, m. r. 1998: the semiannual oscillation and antarctic climate, part 2: recent changes. antarct. sci. 10, 184–191. vinje, t. 2001: anomalies and trends of sea-ice extent and atmospheric circulation in the nordic seas during the period 1864–1998. j. clim.14, 255–267. wadhams, p. & davis, n. r. 2000: further evidence of ice thinning in the arctic ocean. geophys. res. lett. 27, 3973– 3975. winsor, p. 2001: arctic sea ice thickness remained constant during the 1990s. geophys. res. lett. 28, 1039–1041. xie, p. & arkin, p. a. 1996: analyses of global monthly precipitation using gauge observations, satellite estimates and numerical model predictions. j. clim. 9, 840–858. zhang, j. & hibler, w. d. iii 1997: on an effi cient numerical method for modeling sea ice dynamics. j. geophys. res. 102(c4), 8691–8702. zhang, j., rothrock, d. & steele, m. 2000: recent changes in arctic sea ice: the interplay between ice dynamics and thermodynamics. j. clim. 13, 3099–3114. dedomenico05.indd 141de domenico et al. 2004: polar research 23(2), 141–146 thanks to their metabolic potential and wide biodiversity micro-organisms play a fundamental role in making biodegradation processes more effi cient, and in transforming recalcitrant macromolecules into chemical substances more amenable to further metabolization. psychrotrophic bacteria, which are adapted to a wide temperature range and to other fl uctuating conditions such as low nutrient availability, low water activity and high pressure, may have important advantages in biotechnological applications (gounot 1991; mohn et al. 1997) such as the removal of pollutants from cold environments. cripps (1990) claimed that hydrocarbons, both aliphatic and aromatic, present in the southern ocean are above all of a biogenic nature and can be considered as part of the natural background. however, human activities in antarctica (such as tourism, research and fi shing, all of which require fossil fuels for transport and energy), potentially make petroleum hydrocarbons the most likely source of pollution in antarctic ecosystems (bícego et al. 1996; cripps & shears 1997; ferguson et al. 2003). several studies have shown that pollution is actually a localized phenomenon closely connected to human activity (karl 1993; tumeo & wolk 1994). evaporation and photo-oxidation represent the fi rst steps in the disappearance of hydrocarbons from seawater, while microbial degradation, along with weathering processes, is the ultimate fate of oil at sea (leahy & colwell 1990). in the past few years new species of marine bacteria capable of biodegrading hydrocarbons have been isolated from various marine areas (delille & vaillant 1990; bícego et al. 1996; delille et al. 1998; gentile et al. 2003; yakimov et al. 2003). however, natural microbial degradation is slow and diffi cult in the marine environments due to the low concentrations of nitrogen, phosphorous salts and oxygen, and the formation of water-in-oil emulsion and tar balls. furthermore, biodegradation is often limited by the antimicrobial effect of petroleum components (leahy & colwell 1990; heipieper et al. 1992), the toxicity of the watersoluble oil fraction and—more indirectly—by a general inhibition of biological processes due to the increase of uv radiation with decreasing protection by the ozone layer. pollutants other than hydrocarbons have been detected in antarctic seawater. among these, polychlorinated biphenyls (pcbs) are long-term persistent compounds widely utilized in industrial applications for their heat resistance, lipophilicity diesel oil and pcb-degrading psychrotrophic bacteria isolated from antarctic seawaters (terra nova bay, ross sea) maria de domenico, angelina lo giudice, luigi michaud, marcello saitta & vivia bruni fifty-seven antarctic marine bacteria were examined for their ability to degrade commercial diesel oil as the sole organic substrate at both 4 °c and 20 °c. based on the preliminary screening, two isolates (b11 and b15) with high capacity to degrade diesel oil were selected and their biodegradation effi ciency was quantifi ed by gas chromatographic analysis. as expected for psychrotrophs, diesel oil biodegradation was slower at 4 °c than at 20 °c. the two strains also mineralized the c28 n-paraffi n octacosane at 20 °c and polychlorinated biphenyls (pcbs) at 4 °c and 20 °c. m. de domenico, a. lo giudice, l. michaud & v. bruni, department of animal biology and marine ecology, university of messina, salita sperone 31, it-98166 messina, italy, vivia.bruni@unime.it; m. saitta, department of organic and biological chemistry, university of messina, salita sperone 31, it-98166 messina, italy. 142 diesel oil and pcb-degrading psychrotrophic bacteria from antarctic seawater and relative inertness (master & mohn 1998; vaillancourt et al. 2003). in the present study, two psychrotrophic marine strains from antarctica (namely, b11 and b15) were selected from 57 isolates because they had a strong ability to degrade diesel oil, as demonstrated by their noticeable growth in a culture medium containing this substrate as sole carbon source. their biodegradative potential on diesel oil as well as on pcbs was estimated by gas chromatography, in order to assess whether they could be a useful tool for the removal of these organic pollutants from marine environments. materials and methods bacterial strains the psychrotrophic bacterial strains used in this study were previously isolated (maugeri et al. 1996) from antarctic seawater samples (terra nova bay, ross sea) collected along the water column (0 200 m) in two fi xed stations: 23 from mergellina (mer: 74° 41' 33" s 164° 07' 15" e; about 250 m from the coast) and 34 from santa maria novella (smn: 74° 43' s 164° 16' e; in the middle of terra nova bay, about 10.5 km from mer). from among the total of 152 bacterial strains isolated by maugeri et al. (1996), these 57 strains were selected, on the basis of their lipolytic activity on tween 80 (sierra 1957). the isolates are maintained at 4 °c on slopes of marine agar (from difco) and routinely streaked on agar plates from tubes every six months to control purity and viability. antarctic strains are also preserved by freezing cell suspensions at –80 °c in marine broth (difco) to which 20 % (vol/vol) glycerol is added. growth conditions hydrocarbon degradation was screened on a mineral liquid medium (mills et al. 1978) supplemented with commercial diesel oil at a fi nal concentration of 1 % (vol/vol). ten-millilitre portions of the medium were placed in pre-sterilized screw cap tubes and 100 µl of pre-sterilized commercial diesel oil was added to each portion. the medium was inoculated with 100 µl of a bacterial suspension previously prepared in distilled water supplemented with 3 % (wt/vol) nacl. the effect of temperature on the biodegradative activity was determined by cultivation at 4 °c and 20 °c for one month and one week, respectively, on a rotary shaker operated at 100 rpm in order to guarantee a continuous supply of oxygen. turbidity was the positive indicator. uninoculated control tubes were incubated in parallel to monitor abiotic losses of the substrate. all assays with uninoculated controls were performed in duplicate. two strains (b11 and b15) seemed to have a strong degradation effect on diesel oil at both 4 °c and 20 °c. based on these preliminary results, their ability to mineralize both the longchain alkane octacosane (c28) and a pcb mixture (aroclor 1242) was examined. the mineral liquid medium was supplemented with octacosane or pcbs at a fi nal concentration of 0.2 % (wt/vol and vol/vol, respectively). removal of these substrates was recorded after incubation at 4 °c and 20 °c. both strain b11 and strain b15 had been isolated from samples taken at the santa maria novella sampling station at a depth of 5 m. gas chromatographic analysis gas chromatographic analysis was performed for strains b11 and b15 grown on diesel oil, octacosane (c28) and pcbs. in addition, strain d41 (isolated from the santa maria novella station at the depth of 200 m) and strain d48 (isolated from surface water from mergellina) were randomly chosen among those that made the culture medium turbid at 4 °c, but did not seem to grow on diesel oil as the sole carbon source at 20 °c. following the incubation periods, the cultures of each tube were extracted twice with 20 ml of n-hexane as a solvent by using separatory funnels to remove the cellular material. the extracts were transferred to tared vials. the volume of each extract was adjusted to 100 ml by adding more n-hexane, and vials were kept at 4 °c until the gas chromatographic analysis was carried out. biodegradation of hydrocarbons was quantifi ed by quantitative gas chromatographic analysis using a dani 8521-a gc equipped with an se-54 fused silica capillary column (25 m × 0.32 mm i.d.; 0.45 µm fi lm thickness) and a fl ame ionization detector. hydrogen (1 kg/cm2) was used as the carrier gas. the temperature program consisted of an initial oven temperature of 50 °c for 5 min increased at a rate of 10 °c/min to 280 °c for 10 min and then isothermal for 10 min. injector and detector temperatures were maintained at 280 °c. the splitting ratio was 1:60. 143de domenico et al. 2004: polar research 23(2), 141–146 pcb degradation was determined by quantitative gas chromatography using a carlo erba mega 5300 gc equipped with an electron capture detector and an spb-5 fused silica capillary column (30 m × 0.25 mm i.d.; 0.25 µm fi lm thickness). helium (1.5 kg/cm2) was used as the carrier gas. the initial oven temperature was 150 °c, increased to 230 °c at a rate of 2 °c/min and then increased to 280 °c at a rate of 10 °c/min (10 min hold). the temperature of the injector and the detector were 250 °c and 280 °c respectively. nitrogen (1.5 kg/cm2) was the gas at the detector. the splitting ratio was 1:25. the degradation was expressed as the percentage of substrate degraded in relation to the amount of the remaining fractions in the appropriate abiotic control samples (external standard technique). the biodegradation effi ciency (be), based on the decrease in the substrate concentration as a whole, was evaluated by using the following expression: be (%) = 100 – (as × 100/aac) where as is the total area of peaks in each sample, aac is the total area of peaks in the appropriate abiotic control and be (%) is the biodegradation effi ciency. results during this study, all but six of the 57 lipolytic isolates screened grew on diesel oil as the sole source of carbon and energy. twenty-one of the strains from mer and 30 of the strains from smn showed an ability to biodegrade diesel oil at at least one of the temperatures tested (fig. 1). the number of diesel oil-degrading bacteria isolated from each sampling depth in relation to the temperature of incubation is shown in fi gure 2. twenty-eight isolates (13 from mer and 15 from smn) degraded diesel oil at 4 °c exclusively (assessed after a month of incubation), while six (all from smn) did so only at 20 °c (assessed after a week of incubation). diesel oil was observed to be utilized at both temperatures by 17 strains only: nine of them were isolated from smn and eight from mer. among these isolates strains b11 and b15 gave the highest turbidity. quantitative gas chromatographic analysis allowed the estimation of their biodegradation fig. 1. distribution of the 51 diesel oil-degrading bacteria in relation to their origin (sampling station and depth). strains utilizing the substrate at at least one of the temperatures are included. fig. 2. distribution of diesel oil-degrading bacteria in relation to the incubation temperature and to the depth. the appearance of turbidity was used as the positive indicator. 144 diesel oil and pcb-degrading psychrotrophic bacteria from antarctic seawater effi ciency, which was expressed as the percentage of substrate degraded (fig. 3). very little difference was observed between the degradation of diesel oil by strain b11 at 4 °c and 20 °c. in culture medium inoculated with strain b15, 66.7 % of the diesel oil had disappeared after the onemonth incubation at 4 °c and 50.5 % had disappeared after one week at 20 °c. a signifi cant diesel oil mineralization was observed for strains d41 and d48 at 20 °c (66.10 % ± 2.55 [mean ± sd] and 56.15 % ± 0.49 [mean ± sd], respectively). the biodegradative activity was confi rmed by the calculation of the c17:pristane and c18:phytane ratios (table 1). strains b11 and b15 also mineralized the c28 n-paraffi n octacosane at 20 °c and pcbs at 4 °c and 20 °c as the sole carbon source. strain b11 utilized 31.9 % and 62.8 % of the pcb mixture at 4 °c and 20 °c, respectively, while 22.8 % and 30.8 % of the substrate disappeared from the culture medium inoculated with strain b15 after incubation at 4 °c and 20 °c, respectively. discussion diesel oil is a complex combination of hydrocarbons deriving from the distillation of crude oil and represents an excellent substrate in the study of hydrocarbon biodegradation thanks to its composition (bicca et al. 1999). diesel oil contains 2000 to 4000 different hydrocarbons (marchal et al. 2003) with a carbon number ranging approximately from c9 to c20, including paraffi n, olefi ns, naphtha and aromatic compounds. during the screening for the degradation of diesel oil, only 6 of the 57 lypolitic isolates did not mineralize the substrate, despite their ability to hydrolyse tween 80. this highlights the strong relationship between lipolytic activity and the biodegradation of diesel oil as previously shown by mills et al. (1978). the amounts of diesel oil mineralized by strains b11 and b15 at both the temperatures tested were very similar. since extraction for the gas chromatographic analysis was carried out after a month of culture at 4 °c and after a week at 20 °c, this fi nding suggests that both strains degraded diesel oil more slowly at 4 °c than at 20 °c, as expected for psychrotrophs. this is in line with the effect of temperature on the rate of hydrocarbon metabolism by micro-organisms: metabolism decreases with decreasing temperature. the signifi cant diesel oil mineralization by strains d41 and d48 at 20 °c should be highlighted. these strains had been randomly chosen amongst those that showed growth at 4 °c but not at 20 °c as indicated by the turbidity of the culture medium. in this kind of qualitative screening, the assumption of hydrocarbon utilization cannot be based only on the appearance of turbidity; instead a chromatographic analysis of the culture is needed. on the other hand, mills et al. (1978) showed that in liquid media it is possible that micro-organisms only grow in the oily phase, producing neither visible growth in the oil–water interface nor visible turbidity in the water phase. mills and co-workers suggested that in such cases the quantity of proteins in the culture should be determined because production of protein in quantities greater than 30 µg/l is correlated to easily visible turbidity. however, as is well known, one must take into account that the rate of hydrocarbon degradation is not always directly related to the bacterial growth. the c17:pristane and c18:phytane ratios were generally characterized by lower values than the fig. 3. percentage of diesel oil, pcb and c28 biodegraded by the strains b11 and b15. table 1. c17:pristane and c18:phytane ratios. sample incubation temperature (°c) c17:pristane ratio c18:phytane ratio abiotic control 4 and 20 2.2 2.1 strain b11 4 1.7 2.2 strain b15 4 1.2 1.5 strain b11 20 1.3 1.5 strain b15 20 1.1 1.1 strain d41 20 1.4 1.6 strain d48 20 0.7 0.5 145de domenico et al. 2004: polar research 23(2), 141–146 abiotic control. pristane, widely employed as an internal standard for the analysis of hydrocarbon samples, is characterized by a high degree of persistence (watkinson & morgan 1990). thus, its disappearance from the culture medium demonstrates the occurrence of biodegradation. the biodegradation effi ciencies on pcbs were lower than those observed for diesel oil. this is not surprising as pcbs are highly recalcitrant to biodegradation. lower incubation temperature severely limited pcb degradation. in fact, the removal of pcb by bacterial degradation was higher at 20 °c. after only a week of incubation at 20 °c the disappearance of pcbs was two-fold higher than at 4 °c after a month. yakimov et al. (1999), searching for bioemulsifi er-producing bacteria, selected the strains b11 and b15 and identifi ed them at molecular level as marine variants of rhodococcus fascians. psychrotrophic alkane-degrading members of the genus rhodococcus sp. have also been isolated from a number of cold environments (whyte et al. 1996, 1998, 2002; bej et al. 2000). rhodococci have been found to utilize a variety of xenobiotic compounds as carbon source (seto et al. 1995; larkin et al. 1998) and to possess a variety of alkane-catabolic pathways (whyte et al. 1998; smits et al. 1999; andreoni et al. 2000). the results obtained confi rm that culturable antarctic bacteria are capable of degrading hydrocarbons, both at 4 °c and at 20 °c. as many authors state (atlas 1981; bertrand et al. 1993; whyte et al. 1997; delille & delille 2000), the exposure of the microbial community to hydrocarbons is responsible for its potential to oxidize these compounds and, consequently, for the number of micro-organisms able to utilize them. also delille & vaillant (1990), who did in situ and laboratory experiments to investigate the effect of crude oil on the growth of sub-antarctic marine bacteria, found that the addition of hydrocarbons always induced a marked, rapid increase in the bacterial population. it is therefore surprising that hydrocarbon-degrading marine bacteria were isolated from both superfi cial and deep seawaters with hydrocarbon pollution levels as low as those of the antarctic. thus, the occurrence of these bacteria in terra nova bay could probably be related to the presence of hydrocarbons of natural origin rather than to the impact deriving from human activities in antarctica. in conclusion, the ability of psychrotrophic marine bacteria of antarctic origin to utilize diesel oil and pcbs as the sole carbon source was demonstrated. although the experiments were performed in batch culture under stable conditions different from those of natural environments, this kind of screening is an essential step in the evaluation of bacteria biodegradation effi ciency. in accordance with whyte et al. (1998), our results suggest that psychrotrophic microorganisms, which clearly utilize a wide variety of hydrocarbons at temperatures ranging from 0 °c to 30 °c, may be better suited for in situ bioremediation in both temperate and cold environments than mesophiles or psychrophiles. acknowledgements.—this research was supported by the italian national research project in antarctica (pnra). references andreoni, v., bernasconi, s., colombo, m., van beilen, j. b. & cavalca, l. 2000: detection of genes for alkane and naphthalene catabolism in rhodococcus sp. strain 1bn. environ. microbiol. 2 (5), 572–577. atlas, r. m. 1981: microbial degradation of petroleum hydrocarbons: an environmental perspective. microbiol. rev. 45, 180–209. bej, a., saul, d. & aislabie, j. 2000: cold-tolerant alkanedegrading rhodococcus species from antarctica. polar biol. 23, 100–105. bertrand, j. c., bianchi, m., al mallah, m., acquaviva, m. & mille, g. 1993: hydrocarbon biodegradation and hydrocarbonoclastic bacterial communities composition grown in seawater as a function of sodium chloride concentration. j. exp. mar. ecol. 168, 125–138. bicca, f. c., fleck, l. c. & ayub, m. a. z. 1999: production of biosurfactant by hydrocarbon degrading rhodococcus ruber and rhodococcus erythropolis. rev. microbiol. 30, 231–236. bícego, m. c., weber, r. r. & ito, r. g. 1996: aromatic hydrocarbons on surface waters of admiralty bay, king george island, antarctica. mar. pollut. bull. 32, 549–553. cripps, g. c. 1990: hydrocarbons in the seawater and pelagic organisms of the southern ocean. polar biol. 10, 393–402. cripps, g. c. & shears, j. 1997: the fate in the marine environment of a minor diesel fuel spill from an antarctic research station. environ. monit. assess. 46, 221–232. delille, d., basseres, a., desommes, a. & rosiers, c. 1998: infl uence of daylight on potential biodegradation of diesel and crude oil in antarctic seawater. mar. environ. res. 45, 249–258. delille, d. & delille, b. 2000: field observations on the variability of crude oil impact on indigenous hydrocarbondegrading bacteria from sub-antarctic intertidal sediments. mar. environ. res. 49, 403–417. delille, d. & vaillant, n. 1990: the infl uence of crude oil on the growth of subantarctic marine bacteria. antarct. sci. 2, 123–127. 146 diesel oil and pcb-degrading psychrotrophic bacteria from antarctic seawater ferguson, s. h., franzmann, p. d., snape, i., revill, a. t., trefry, m. g. & zappia, r. 2003: effects of temperature on mineralisation of petroleum in contaminated antarctic terrestrial sediments. chemosphere 52, 975–987. gentile, g., bonasera, v., amico, c., giuliano, l. & yakimov m. 2003: shewanella sp. ga-22, a psychrophilic hydrocarbonoclastic antarctic bacterium producing polyunsaturated fatty acids. j. appl. microbiol. 95, 1124–1133. gounot, a. m. 1991: bacterial life at low temperature: physiological aspects and biotechnological implications. j. appl. bacteriol. 71, 386–397. heipieper, h. j., diefenbach, r. & keweloh, h. 1992: conversion of cis unsatured fatty acids to trans, a possible mechanism for the protection of phenol-degrading pseudomonas putida p8 from substrate toxicity. appl. environ. microbiol. 58, 1847–1852. karl, d. m. 1993: microbial processes in the southern oceans. in e. i. friedmann (ed.): antarctic microbiology. pp. 1–63. new york: wiley-liss, inc. larkin, m. j., allen, c. c. r., kukalov, l. a. & nagy, i. 1998: purifi cation and characterization of a novel naphtalene dioxygenase from rhodococcus sp. strain nicmb12038. j. bacteriol. 181, 6200–6204. leahy, j. g. & colwell, r. r. 1990: microbial degradation of hydrocarbons in the environment. microbiol. rev. 54, 305–315. marchal, r., penet, s., solano-serena, f. & vandecasteele, j. p. 2003: gasoline and diesel oil biodegradation. oil & gas science and technology – rev. inst. fr. pet. 58, 441–448. master, e. r. & mohn, w. w. 1998: psychrotolerant bacteria isolated from arctic soil that degrade polychlorinated biphenyls at low temperatures. app. environ. microbiol. 64, 4823–4829. maugeri, t. l., gugliandolo, c. & bruni, v. 1996: heterotrophic bacteria in the ross sea (terra nova bay, antarctic). microbiologica 19, 67–76. mills, a. l., breuil, c. & colwell, r. r. 1978: enumeration of petroleum-degrading marine and estuarine microorganisms by the most probable number method. can. j. microbiol. 24, 552–557. mohn, w. w., westerberg, k., cullen, w. r. & reimer, k. j. 1997: aerobic biodegradation of biphenyl and polychlorinated biphenyls by arctic soil micro-organisms. appl. environ. microbiol. 63, 3378–3384. seto, m., kimbara, k., shimura, m., hatta, t., fukuda, m. & yano, k. 1995: a novel transformation of polychlorinated biphenyls by rhodococcus sp. strain rha1. appl. environ. microbiol. 61, 3353–3358. sierra, g. 1957: a simple method for the detection of lipolytic activity of micro-organisms and some observations on the infl uence of the contact between cells and fatty acid substrates. antonie van leeuwenhoek 23, 15. smits, t. h. m., röthlisberger, m., witholt, b. & van beilen, j. b. 1999: molecular screening for alkane hydroxylase genes in gram-negative and gram-positive strains. environ. microbiol. 1, 307–316. tumeo, m. a. & wolk, a. e. 1994: assessment of the presence of oil-degrading microbes at mcmurdo station. antarctic journal u.s. 29 (5), 375–377. vaillancourt, f. h., haro, m. a., drouin, n., karim, z., maaroufi , h. & eltis l. d. 2003: characterization of extradiol dioxygenases from a polychlorinated biphenyl-degrading strain that possess higher specifi cities for chlorinated metabolites. j. bacteriol. 185, 1253–1260. watkinson, r. j. & morgan, p. 1990: physiology of aliphatic hydrocarbon-degrading micro-organisms. biodegradation 1, 79–92. whyte, l. g., bourbonnière, l. & greer, c. w. 1997: biodegradation of petroleum hydrocarbons by psychrotrophic pseudomonas strains possessing both alkane (alk) and naphthalene (nah) catabolic pathways. appl. environ. microbiol. 63, 3719–3723. whyte, l. g., greer, c. w. & innis, w. e. 1996: assessment of the biodegradation potential of psychrotrophic microorganisms. can. j. microbiol. 42, 99–106. whyte, l. g., hawari, j., zhou, e., bourbonnière, l., innis, w. e. & greer, c. w. 1998: biodegradation of variablechain-length alkanes at low temperatures by a psychrotrophic rhodococcus sp. appl. environ. microbiol. 64, 2578–2584. whyte, l. g., schultz, a., van beilen, j. b., luz, a. p., pellizari, v., labbé, d. & greer, c. w. 2002: prevalence of alkane monooxygenase genes in arctic and antarctic hydrocarbon-contaminated and pristine soils. fems microbiol. ecol. 41, 141–150. yakimov, m. m., giuliano, l., bruni, v., scarfì, s. & golyshin, p. n. 1999: characterization of antarctic hydrocarbon-degrading bacteria capable of producing bioemulsifi ers. microbiologica 22, 249–256. yakimov, m. m., giuliano, l., gentile, g., crisafi , e., chernikova, t. n., abraham, w. r., lünsdorf, h., timmis, k. n. & golyshin, p. n. 2003: oleispira antarctica gen. nov., sp. nov., a novel hydrocarbonoclastic marine bacterium isolated from antarctic coastal sea water. int. j. syst. evol. microbiol. 53, 779–785. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <feff004e00e4006900640065006e002000610073006500740075007300740065006e0020006100760075006c006c006100200076006f0069006400610061006e0020006c0075006f006400610020005000440046002d0061007300690061006b00690072006a006f006a0061002c0020006a006f006900640065006e002000740075006c006f0073007400750073006c00610061007400750020006f006e0020006b006f0072006b006500610020006a00610020006b007500760061006e0020007400610072006b006b007500750073002000730075007500720069002e0020005000440046002d0061007300690061006b00690072006a0061007400200076006f0069006400610061006e0020006100760061007400610020004100630072006f006200610074002d0020006a0061002000520065006100640065007200200035002e00300020002d006f0068006a0065006c006d0061006c006c0061002000740061006900200075007500640065006d006d0061006c006c0061002000760065007200730069006f006c006c0061002e0020004e00e4006d00e4002000610073006500740075006b0073006500740020006500640065006c006c00790074007400e4007600e4007400200066006f006e0074007400690065006e002000750070006f00740075007300740061002e> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice no job name an observation of the banded structure of the antarctic coastal current at the prime meridianpor_166 322..329 ismael núñez-riboni1 & eberhard fahrbach2 1 max planck institute for meteorology, bussestraße 53, de-20146 hamburg, germany 2 alfred wegener institute for polar and marine research, bussestraße 24, de-27570 bremerhaven, germany abstract observations of three bands of westward flow and two countercurrents, spanning roughly 50 km from the ice-shelf edge in front of the fimbul ice shelf (prime meridian) in antarctica, are presented. a comparison with a numerical model and the proximity of two of these current cores to the ice shelf suggest that they split from the antarctic coastal current because of the influence of sea ice on the surface drag. a comparison with previous studies suggests that the other core is the current associated with the antarctic slope front. because the fimbul ice shelf overhangs the continental shelf, the antarctic coastal current displaces offshore, getting close to the antarctic slope front. the obtained structure is derived from conductivity–temperature–depth geostrophic velocities from february 2005, referenced with detided acoustic doppler current profiler velocities. keywords antarctic coastal current; antarctic slope front; countercurrent; current bands; sea ice; southern ocean. correspondence núñez-riboni, max planck institute for meteorology, bussestraße 53, de-20146 hamburg, germany. e-mail: ismael.nunez-riboni@zmaw.de doi:10.1111/j.1751-8369.2010.00166.x in the atlantic sector of the southern ocean, the antarctic slope front (asf; jacobs 1986) and the antarctic coastal current (acoc; deacon 1937) flow westwards along the antarctic coast as a part of the southern branch of the weddell gyre. the acoc in particlular is a key current for the advection of nutrients and krill (heywood et al. 2004), and acts as a “dynamic barrier”, keeping the warm deep water (wdw) of the weddell sea away from the ice shelf cavity of the antarctic continent (smedsrud et al. 2006). most importantly, the southern branch of the weddell gyre is a major carrier of water masses to the formation areas of antarctic deep water (aadw) and antarctic bottom water (aabw) in the south-western weddell sea (heywood et al. 2004). previous studies have revealed a banded structure of the antarctic coastal flow at three regions around antarctica: gill (1973) and foster & carmack (1976) found that the current along the antarctic continental slope splits into coastal and slope components near 27°w. heywood et al. (1998) found that at 17°w the current associated with the asf is split into two cores (one of them merged with the acoc). near kapp norvegia (12°w), fahrbach, rohardt et al. (1994) also observed two westward bands flowing over the continental slope. the splitting of the coastal flow observed by gill (1973) and foster & carmack (1976) has been attributed to the widening of the continental shelf and the retreat of the coastline away from the continental slope. fahrbach, rohardt et al. (1994) explained the cores they found as a consequence of a step-like shape of the continental slope. however, heywood et al. (1998) did not observe such a structure, and were not able to explain the splitting of the asf. in contrast to a one-banded flow, a multibanded flow generates areas of stronger and weaker horizontal shear, which impact transport (particularly of salt and heat), mixing and dynamics. therefore, precise determination of the banded structure of the antarctic coastal flow at several regions around antarctica is important for identifying influences on the antarctic ecosystem and on antarctic water mass formation. this notion becomes obvious when considering transport estimates, which are generally calculated from geostrophic velocities derived from conductivity–temperature–depth (ctd) measurements from ships and/or with moored instruments. both methods overlook the banded structure of the antarctic coastal flow if the measurements do not occur in sufficient spatial resolution (e.g., thompson & heywood 2008). at the prime meridian, the horizontal structure of the antarctic coastal flow has been, until now, fully unknown. the present study fills this gap, addressing the question of the banded structure being permanent in time and space around antarctica. polar research 29 2010 322–329 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd322 mailto:riboni@zmaw.de data description and analysis the structure of the antarctic coastal flow at the prime meridian was determined from measurements of ctd, and from ship-borne acoustic doppler current profiler (adcp) data from the rv polarstern ant-xxii/3 expedition on 17 and 18 february 2005. these data and the area of study are depicted in fig. 1. the adcp data are extracted into a 0.01° ¥ 0.01° horizontal grid (approximately 0.4 km ¥ 1 km in the study region). to estimate the effect of internal waves generated by the baroclinic tides on the observed density field, the ratio between the variance of barotropic and baroclinic tides in the study region is calculated. barotropic tides are calculated as the vertical mean of high-passed velocities (cut-off period of 7 days) of a current metre mooring positioned at the prime meridian and at 69.4°s (pangaea 2008), ca. 22 km away from the ice shelf (fig. 1). the mean instrument depths are 247, 744 and 1925 m (in a water depth of 1975 m; fig. 2a). baroclinic tides are calculated from the deviation of the individual time series from the vertical mean. only the period of time in which the ctd section was taken is considered. these measurements show that the vertical mean variance of the baroclinic tides is 6.2% of the variance of the barotropic tides. therefore, the tides in the zone are essentially barotropic, and the effect of internal waves caused by baroclinic tides is minor. the root mean square (rms) velocity of the barotropic tide during the ctd section at the prime meridian of ant-xxii/3 is 1.9 cm s-1, which represents 14.0% of the rms velocity from the adcp (13.7 cm s-1). these comparatively small tidal velocities are a consequence of low tidal amplitude in the study region (depths larger than fig. 1 (a) the grey rectangle near the coast in the eastern weddell sea indicates the study area in the southern ocean. (b) in a closer view of the area of study, arrows show the subsampled (for clarity) acoustic doppler current profiler (adcp) data of the polarstern antxxii/3 expedition (21 january–6 april 2005). the seaward edge of the fimbul ice shelf is indicated with a thick black line. isobaths are given in 500-m steps, from 500 to 4000 m depth (vanney & johnson 1985). current velocities can be derived from the reference arrow in the lower left corner. diamonds mark the positions of the conductivity– temperature–depth stations. the station inside the ring marks the position where the mooring used to detide the adcp data was deployed. banded structure of the antarctic coastal currenti. núñez-riboni & e. fahrbach polar research 29 2010 322–329 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 323 1500 m), together with the fact that the observations were taken during neap tide, as corroborated with the mooring time series. such small tidal velocities are close to the accuracy of the adcp (garcia-gorriz et al. 1997). although this suggests that the detiding of adcp data is of little effect in our results, the tides are removed from the adcp velocities as follows. the phase and velocity amplitude of the zonal velocity of each tidal harmonic are found with a least-squares minimization between mooring velocities and the sum of four harmonic functions, representing the principal tidal harmonics m2, s2, k1 and o1. an amplification factor for each tide harmonic is calculated as the amplitude change from the digitized co-tidal charts of robertson et al. 1998 (their plate 1) between the mooring position and each adcp data point. the phase shift for each tidal harmonic is calculated similarly. tidal velocities of each harmonic are extrapolated from the mooring time series to each adcp data point using the amplification factor and phase shift. finally, the sum of the extrapolated four harmonics, m2, s2, k1 and o1, at each adcp data point is subtracted from the adcp zonal velocity. this method is preferred to the direct subtraction of modelled tidal velocities (i.e., without using the mooring velocities) because it reproduces the mooring tide velocities with minimum rms differences. robertson et al.’s fig. 2 (a) geostrophic velocities derived from conductivity–temperature–depth (ctd) measurements referenced with detided acoustic doppler current profiler (adcp) velocities (positive eastwards). (b) potential density anomaly sq referred to the surface (kg m-3). (c) potential temperature. the thin dashed lines indicate the position of the ctd stations.the numbers at the top indicate the meridional distance (km) to the southernmost station. bold vertical lines mark the current cores, which are identified with s for south, m for middle and n for north. the thick black contours in (a) indicate zero-velocity isolines, the diamonds show the positions of the moored instruments used to detide the adcp velocities, and the grey disc at the surface (near 69.5°s) shows the position where sea ice with 10% concentration was observed in the aspect programme. the southern end of the displayed transect (69.6°s) denotes the edge of the fimbul ice shelf, as inferred from gps positions from the rv polarstern. data farther north of the northernmost station has not been extrapolated, but has instead been interpolated with a station not shown in the figure. the depth axes are divided in two, from 0 to 500 m and from 500 to 3500 m. banded structure of the antarctic coastal current i. núñez-riboni & e. fahrbach polar research 29 2010 322–329 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd324 (1998) model is preferred above the high-latitude tidal models of the earth and space research institute and oregon state university, tpxo7.1 (egbert & erofeeva 2002) and cats2008 (cats 2008; padman, pers. comm.) because rms differences between model velocities extrapolated to the position of a second mooring (69.0°s, 0°e) and the observed tidal velocities are the smallest in the robertson et al. (1998) model. the model results confirm that the observations were taken during neap tide. geostrophic velocities from ctd data are calculated relative to a reference level of 3500 m depth. because the two southernmost stations are not exactly at the prime meridian (but approximately 8 km east and west of it; fig. 1), the geostrophic velocities are projected into the zonal direction using the azimuth between ctd stations. for each pair of ctd stations, the projected profiles of geostrophic velocity are shifted until the mean geostrophic velocity between 50 m and the maximum depth of the adcp (ca. 250 m) matched the mean zonal detided adcp velocity between the stations (for the same depth range). only adcp data deeper than 50 m is considered to avoid the influence of the ship and the ekman layer, which is thinner than 40 m, as calculated following willebrand (1989). the bathymetry used is the one-minute grid of the general bathymetric chart of the oceans (vanney & johnson 1985). sea-ice observations were taken on-board the polarstern and are now available from the data archive antarctic sea ice processes and climate (aspect 2008). results the absolute zonal geostrophic velocities (fig. 2a) show that the coastal flow at the prime meridian is approximately 50 km wide at the surface, and is split in three westward current bands: at 69.54°s (labelled s, for south), 69.38°s (labelled m, for middle) and 69.11°s (labelled n, for north). the cores are also visible in the density field (fig. 2b), with isopycnals sq inclined downwards towards the coast. an uncertainty for the zonal geostrophic velocity of s could arise because of the unknown velocity component parallel with the line connecting the two southernmost ctd stations (fig. 1). however, because the velocity field is prescribed at the surface with adcp data, the uncertainty is related only to the shear of s. centred at the continental slope (69.29°s) and at the ice-shelf edge (69.55°s), there are two countercurrents at the sea bed, with eastward velocities of ca. 5 and 10 cm s-1, respectively (fig. 2a). the transport of the first countercurrent is ca. 1.6 sv. the second countercurrent seems to be partially under the ice shelf, and therefore its transport cannot be estimated. a patch of warm water near 69.5°s at a depth of 100 m suggests downwelling (fig. 2c). to estimate the effect on the transport calculations when the banded structure of the current is not considered (e.g., thompson & heywood 2008), the geostrophic transport has been calculated by using all ctd stations and by removing the ctd station at 69.5°s, which merged the two bands near the ice shelf into one. the transport is underestimated by 12% if this ctd station is removed, suggesting that the omission of the banded structure yields a significant transport inaccuracy. discussion heywood et al. (1998) mention the splitting of the current associated with the asf into two cores. they state that the southern core is merged with the acoc in their study region, and match this splitting with that of the “eastern boundary currents” of the weddell gyre observed by fahrbach, rohardt et al. (1994). both studies observe a current core near the ice front and a slower core offshore (heywood et al. 1998: fig. 5b; fahrbach, rohardt et al. 1994: fig. 6). in the case of heywood et al. (1998), the southern core has a speed of 30 cm s-1 and the northern core has a speed of 20 cm s-1, and they are separated from each other by ca. 50 km. these observations coincide roughly with cores m (ca. 30 cm s-1) and n (ca. 12 cm s-1) in this paper, which are separated by ca. 30 km from each other. in both previous studies, the southern core has been observed to flow along the ice-shelf front, in regions of strong density gradients in which the isopycnals slope downward towards the coast. south of 69.3°s, the same density structure is observed at the prime meridian (fig. 2b; also observed by fahrbach, rohardt et al. [1994], and modelled by smedsrud et al. [2006]), where bands s and m are located. the northern band reported in both previous studies flows over the deeper part of the continental slope (at a depth of ca. 3000 m), which is also the position of n (ca. 3100 m; fig. 2a). these correspondences suggest that s and m are related to the near-shore core observed by heywood et al. (1998) and fahrbach, rohardt et al. (1994), i.e., the acoc and n to their offshore core (the current associated with the asf). whereas the acoc normally flows over the continental shelf of antarctica (heywood et al. 2004), the current is generated mainly by the wind, which piles up water against the ice shelf front as a result of ekman transport. therefore, the fimbul ice shelf overhanging the continental shelf (fig. 1) displaces the current offshore, and brings it closer to the asf. banded structure of the antarctic coastal currenti. núñez-riboni & e. fahrbach polar research 29 2010 322–329 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 325 whereas heywood et al. (1998) found that the asf splits into two cores, they did not observe any splitting of the acoc. however, they could not explain the splitting of the asf. the step-like topography related to a plateau in the continental slope at intermediate depth that fahrbach, rohardt et al. (1994) observed, and which they proposed to generate the cores, was not observed by heywood et al. (1998). in the present study, there is also no evidence of plateau-like structures to yield the current bands. zonation resulting from the beta plane (e.g., sokolov & rintoul 2007) is also improbable: the rhines scale (rhines 1975), characterizing the conditions under which bands are formed in the study region, is ca. 700 km (eqn. 5 of read et al. [2007], using a typical velocity of 20 cm s-1 at 69°s). this value is considerable larger than the observed distance between the bands. on the other hand, splitting of the acoc (and not of the asf) by sea ice is a more likely cause for the observed current bands. to provide evidence that a strip of sea ice in front of the antarctic ice shelf can divide the acoc into bands, solutions of hydrostatic boussinesq equations for a flat-bottomed, f-plane ocean near an ice shelf (fennel & johannessen 1998) were used. the contribution of the pressure gradient resulting from water piled against the ice-shelf front by ekman transport (fig. 3a, d) is obtained from the first term of eqn. 32 of fennel & johannessen (1998): the non-oscillatory part of the solution to the problem of the fixed ice shelf (clarke 1978). the contribution to the velocity field of a strip of sea ice (fig. 3b, e) is obtained from the solution of eqn. 54 of fennel & johannessen (1998), by taking by taking their constants c0 and a0 as zero (these measures neglect the wind stress fig. 3 (a–c) wind stress profiles. (d–f) the resulting zonal velocity fields derived from the theory of fennel & johannessen (1998). in (a) and (d) the problem of the fixed ice shelf is shown. using eqn. 32 of fennel & johannessen (1998), (a) shows a constant wind stress over the open ocean, whereas (d) shows the non-oscillatory part of the solution: a geostrophic along-edge jet in downwind direction in front of the ice shelf and a countercurrent underneath. stress generated by a strip of zonally moving sea ice is shown in (b), and (e) shows the corresponding downwind jet. (c) the sum of both wind stresses and (f) resulting velocity fields are also represented. the ice-shelf front is represented by the horizontal thick lines. the region in which y < 0 is the antarctic continent; the region in which y > 0 is the ocean. the wind stress represents winds towards the west. because in fennel & johannessen (1998) the wind is assumed to force the ocean evenly across the mixed layer, the wind stress is scaled by the density and depth of the mixed layer (i.e., the stress is given by the squared friction velocity per unit depth; m s-2). negative current velocities (m s-1) are westwards. the north is upwards. in (f), the two resulting current bands, which would be related to those of fig. 2, are marked with s (for south) and m (for middle). the parameters from the fennel & johannessen (1998) analysis are subjectively chosen: the depth of the mixed layer is taken as 30 m, the friction velocity is taken as 1 cm s-1 and the width of the ice floes is taken as 500 m. the baroclinic rossby radius r is taken as 5 km, based on houry et al. (1987). this solution corresponds to the eighth time step after starting the wind stress (the analysis of fennel & johannessen [1998] is not stationary). banded structure of the antarctic coastal current i. núñez-riboni & e. fahrbach polar research 29 2010 322–329 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd326 over the entire area apart from a band representing the sea-ice strip). the sum of both contributions (fig. 3c, f) is remarkably similar to the observed banded structure of the acoc (fig. 2a). in this solution to the equations of motion of fennel & johannessen (1998), the stress over the sea ice is larger than over the open ocean, which occurs when ridged sea ice is present: the ice behaves like a sail, increasing the drag (luepkes & birnbaum 2005). in agreement with this notion, the on-board ice observations during ant-xxii/3 (aspect 2008) show a strip of first-year sea ice near 69.5°s (fig. 2a). further similarities between the observation and fennel & johannessen’s (1998) theory reinforce this idea: the countercurrent below the ice shelf predicted by fennel & johannessen (1998) and clarke (1978) (fig. 3d) would relate to an eastward velocity of 10 cm s-1 close to the ocean bottom and the ice shelf in fig. 2a. the solution of fennel & johannessen’s (1998) eqn. 54, although with c0 � 0, predicts downwelling at the position of the nearcoast core and a countercurrent seaward of the offshore core (fennel & johannessen 1998: fig. 5). accordingly, s lies near a patch of warm surface water downwelled to 100 m near 69.50°s (water with temperatures equal or higher than -1°c; fig. 2c), and there is a countercurrent immediately north of m (near 69.3°s, fig. 2a). although two countercurrents along the antarctic ice shelf have not yet been observed simultaneously, this is probably because of their different dynamics: the first countercurrent is generated by the blocking action of the ice-shelf front (clarke 1978; fennel & johannessen 1998), and hence it is a permanent feature, but is difficult to observe because it is below the ice shelf. the second countercurrent is linked to the sea ice, and hence it appears seaward of the ice-shelf front, but as a semipermanent feature changing position and intensity. in previous studies there is evidence of either one or the other countercurrent: a countercurrent below the fimbul ice shelf has been modelled by smedsrud et al. (2006), west of 2°w at a depth of ca. 500 m. fahrbach, peterson et al. (1994) found a north-eastward undercurrent (4 cm s-1; their fig. 4) counter to the prevailing coastal flow at a similar depth of the countercurrent at the continental slope in the present study (between 1000 and 1500 m). similarly, heywood et al. (1998) report an undercurrent near 17°w, trapped close to the continental slope and carrying 0.16 sv along the isobaths between 700 and 1100 m. the transport discrepancy between heywood et al. (1998) and the present study (1.6 sv) could be related to different sea-ice conditions, wind and hydrography forcings between the two studies. these similarities with fennel & johannessen’s (1998) theory suggest that the acoc is generated as a single current band by ekman transport piled against the iceshelf front. the acoc splits in two current bands because of the increased wind drag of sea ice compared with open water: a strip of sea ice flowing along the ice shelf (separated from it by a polynya) generates a band of high velocity. the intensity of this current band depends on the influence of the sea ice on the surface drag coefficient, i.e., on the roughness and concentration of the sea ice. the only disagreement between theory and observation is the position of the sea-ice strip: in the observation it lies between the two cores (fig. 2a), rather near the slow core s, whereas in the theory it lies over the fast core m (fig. 3). such discrepancies are usual when comparing observations and numerical models, and can be related to various factors: coarse spacing between ctd stations, human errors in the sea-ice observations, or greater complexity in the actual influence of the sea ice on the dynamics of currents than in the simplified scheme presented by fennel & johannessen (1998). a scenario in agreement with the notion of heywood et al. (1998) is also possible: core m could be part of the current associated with the asf, whereas core s alone would constitute the acoc (i.e., the asf would split into cores m and n). then again, as there is no obvious reason for the splitting of the asf, splitting of the acoc as a result of sea ice seems to be the most probable scenario. finally, it is worth discussing how representative of the mean conditions of the acoc is the presented geostrophic field: the composite mean velocity of the barotropic component for mid-february (when the ctd section of antxxii/3 was taken) is calculated from the mooring at 69.4°s to be 6 � 4 cm s-1 (filtered to 7 days to eliminate tides). the vertical mean of the absolute geostrophic velocities of ant-xxii/3 for the position of the mooring is 8.9 cm s-1, lying inside the range of the mid-february composite velocity. this suggests that the ctd section of ant-xxii/3 represents a typical flow of the acoc in summer. furthermore, because the sea ice in the study region is normally separated from the ice shelf by a polynya, the banded structures of sea ice and acoc observed in the present study are expected to be common. in previous studies in this region (fahrbach et al. 2004; klatt et al. 2005), the banded structure of the acoc has not been observed because of the coarse spacing between ctd stations or the failure to find a layer of known motion. in order to reveal this structure, it is recommended for future studies that the spacing between ctd stations be equal to or smaller than the smallest distance between the stations of the present study (10 km; fig. 2a). summary and conclusions in the present study, the structure of the antarctic coastal flow at the prime meridian is derived from hydrographic banded structure of the antarctic coastal currenti. núñez-riboni & e. fahrbach polar research 29 2010 322–329 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 327 data from ctd and detided adcp velocities. three bands of westward flow, spanning approximately 50 km off the ice-shelf edge, are revealed. their proximity to the iceshelf front and the similarity of their structure with fennel & johannessen’s (1998) model results suggest that the two near-shore bands are split from the acoc, as a result of the influence of the sea-ice concentration on the surface drag. a countercurrent on the continental slope, also observed in previous studies (fahrbach, peterson et al. 1994; heywood et al. 1998), and downwelling agree with fennel & johannessen’s (1998) scheme, supporting the notion of the influence of sea ice on the dynamics of the acoc. the offshore band could be related to the asf because its position relative to the bottom slope coincides with the position of this front, as observed in previous studies (fahrbach, rohardt et al. 1994; heywood et al. 1998). the velocities of the observed bands and their positions relative to the water mass properties are also those of the acoc and the current associated with the asf, as reported by fahrbach, rohardt et al. (1994) and heywood et al. (1998). the proximity between the acoc and the asf in the present study is related to the fimbul ice shelf overhanging the continental shelf, which displaces the acoc seaward. comparison of the transport estimates from a ctd section including all of the bands, with a section in which one band was ignored, shows that neglecting the bands of the acoc results in an underestimation of the transport by 12%. acknowledgements the kind cooperation of gerd rohardt, boris cisewski, anna akimova, carmen böning, nikolay koldunov and svetlana erofeeva is highly appreciated. discussions with laurence padman and wolfgang fennel are especially acknowledged. the authors are also grateful to the german research foundation for a research grant (geschäftszeichen: fa 436/2-3), to the officers, crew and members of the ctd group of the polarstern ant-xxii/3 expedition, and to four anonymous reviewers (two of whom examined an earlier version of this paper that was rejected) for their helpful suggestions. inr was at the alfred wegener institute for polar and marine research at the time the research reported here was carried out. references aspect 2008. individual ship-based sea-ice observations. antarctic sea ice processes and climate. accessed on the internet at http://www.aspect.aq/data.html on 7 september 2008. cats 2008. cats2008a_opt: circum-antarctic tidal simulation, inverse model version 2008a. accessed on the internet at http://www.esr.org/antarctic/barotropic.html in january 2009. clarke a.j. 1978. on wind-driven quasi-geostrophic water movements near fast-ice edges. deep sea research 25, 41–51. deacon g.e.r. 1937. the hydrology of the southern ocean. discovery reports 15. london: discovery committee colonial office. egbert g.d. & erofeeva s.y. 2002. efficient inverse modeling of barotropic ocean tides. journal of atmospheric and oceanic technology 19, 183–204. fahrbach e., hoppema m., rohardt g., schroder m. & wisotzki a. 2004. decadal-scale variations of water mass properties in the deep weddell sea. ocean dynamics 54, 77–91. fahrbach e., peterson r.g., rohardt g., schlosser p. & bayer r. 1994. suppression of bottom water formation in the southeastern weddell sea. deep-sea research part i 41, 389–411. fahrbach e., rohardt g., schroeder m. & strass v. 1994. transport and structure of the weddell gyre. annales geophysicae 12, 840–855. fennel w. & johannessen o.j. 1998. wind forced responses near ice edges revisited. journal of marine systems 14, 57–79. foster t.d. & carmack e.c. 1976. frontal zone mixing and antarctic bottom water formation in the southern weddell sea. deep-sea research 23, 301–317. garcia-gorriz e., font j. & candela j. 1997. data quality control for vessel mounted acoustic doppler current profiler. application for the western mediterranean sea. scientia marina 61, 417–430. gill a.e. 1973. circulation and bottom water production in the weddell sea. deep-sea research 20, 111–140. heywood k.j., locarnini r.a., frew r.d., dennis p.d. & king b.a. 1998. transport and water masses of the antarctic slope front system in the eastern weddell sea. in s.s. jacobs & r.f. weiss (eds.): ocean, ice, and atmosphere: interactions at the antarctic continental margin. pp. 203–214. washington, d.c.: american geophysical union. heywood k.j., naveira-garabato a.c., stevens d.p. & muench r.d. 2004. on the fate of the antarctic slope front and the origin of the weddell front. journal of geophysical research—oceans 109, c06021, doi: 10.1029/ 2003jc002053. houry s., dombrowsky e., demey p. & minster j. f. 1987. brunt–väisälä frequency and rossby radii in the south atlantic. journal of physical oceanography 17, 1619–1626. jacobs s.s. 1986. the antarctic slope front. antarctic journal of the united states 21, 123–124. klatt o., fahrbach e., hoppema m. & rohardt g. 2005. the transport of the weddell gyre across the prime meridian. deep-sea research part ii 52, 513–528. banded structure of the antarctic coastal current i. núñez-riboni & e. fahrbach polar research 29 2010 322–329 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd328 http://www.aspect.aq/data.html http://www.esr.org/antarctic/barotropic.html luepkes c. & birnbaum g. 2005. surface drag in the arctic marginal sea-ice zone: a comparison of different parameterisation concepts. boundary-layer meteorology 117, 179–211. pangaea 2008. publishing network for geoscientific & environmental data. dois of the moorings data: 10.1594/pangaea.510179–10.1594/pangaea.510182. accessed on the internet at http://www.pangaea.de in august 2007. read p.l., yamazaki y.h., lewis s.r., williams p.d., wordsworth r., miki-yamazaki k., sommeria j. & didelle h. 2007. dynamics of convectively driven banded jets in the laboratory. journal of the atmospheric sciences 64, 4031–4052. rhines p.b. 1975. waves and turbulence on a beta-plane. journal of fluid mechanics 69, 417–443. robertson r., padman l. & egbert g.d. 1998. tides in the weddell sea. in s.s. jacobs & r.f. weiss (eds.): ocean, ice, and atmosphere: interactions at the antarctic continental margin. pp. 341–369. washington, d.c.: american geophysical union. smedsrud l.h., jenkins a., holland d.m. & nost o.a. 2006. modeling ocean processes below fimbulisen, antarctica. journal of geophysical research—oceans 111, c01007, doi: 10.1029/2005jc002915. sokolov s. & rintoul s.r. 2007. multiple jets of the antarctic circumpolar current south of australia. journal of physical oceanography 37, 1394–1412. thompson a.f. & heywood k.j. 2008. frontal structure and transport in the northwestern weddell sea. deep-sea research part i 55, 1229–1251. vanney j.r. & johnson g.l. 1985. gebco bathymetric sheet 5.18 (circum-antarctic). in s.s. jacobs (ed.): oceanology of the antarctic continental shelf. pp. 1–3. washington, d.c.: american geophysical union. willebrand j. 1989. general circulation dynamics. in j. sündermann (ed.): oceanography. pp. 123–150. berlin: springer. banded structure of the antarctic coastal currenti. núñez-riboni & e. fahrbach polar research 29 2010 322–329 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 329 http://www.pangaea.de responses of west greenland humans on foot caribou to the approach of peter aastrup responses to the approach of a human were studied in two caribou populations (akia and isortoq) in west greenland during calving, summer and after the hunt in 1997-98. for each group encountered the distance between the approaching person and the caribou at their first sign of fright (“fright threshold distance”), the distance between the person and the caribou when they began to move away (“flight threshold distance”), and the distance the caribou ran (“run distance”) were measured with a laser range finder. generally, groups of caribou had longer fright threshold, flight threshold and run distances, indicating more vigilance than single individuals. groups with calves were more vigilant than female and male groups, while there was no difference between female and male groups. this pattern was most clear in the akia population. the frequency of curiosity behaviour indicated that the akia caribou were less vigilant than the isortoq caribou after the hunting, while there was no locational difference during the other seasons. caribou in akia were most vigilant during calving, whereas in the isortoq population the highest vigilance was found after hunting. hunting seemed to have heightened awareness in the isortoq population. it is concluded that flight and fright reactions of greenland caribou are similar to those found among other caribou populations, and that precautions should be taken to minimize disturbing caribou during calving. p. aastrup, national environmental research institute, dept. of arctic environment, frederiksborgvej 399, box 358, dk-4000 roskilde, denmark. greenland’s caribouheindeer populations are either wild caribou (rangifer tarandus groenlan dicus), domestic reindeer ( r . t. tarandus) or feral reindeer ( r . t. tarandus). caribou are found in the ice-free region of western greenland where they have lived for centuries without natural predators like wolf, wolverine and bear. today, most of these populations still live in areas with little human disturbance and without predators. but during recent years human activities, including tourism and mineral exploration, have increased in greenland’s formerly pristine areas. quota-based hunting is permitted during a one month period from mid-august to mid-september. hunters usually travel to the general areas by boat and then hike inland to hunt. hunting close to the coast is preferred as the meat has to be carried out. remote inland areas are more or less protected from hunting as hunters normally d o not travel far from coastal areas. mineral exploration activities in caribou calving areas during calving require approval by the bureau of minerals and petro leum. tourism is not regulated. b@ving & post (1997) found that caribou in kangerlussuaq, greenland, were less vigilant than caribou in alaska and suggested that this was an adaptation to the absence of large natural pre dators. klein ( 1 980) claimed that habituation to humans would occur more readily in populations that were not hunted and lived in areas lacking natural predators. greenland caribou could thus be expected to be only slightly affected by distur bances. the present study investigated the reac tions of cariboukeindeer to an approaching human to elucidate the behaviour of caribou in areas relatively undisturbed by man and natural pre aastrup 2000: polar research 19(1), 83-90 83 table i. population and season of observations. akia pop. isortoq pop. total calving 48 25 13 summer 20 61 81 after hunt 34 61 95 total 102 147 249 the kangerlussuaq study site, north of akia and tasersuaq, includes slopes covered with either dwarf shrubs like betulu nana, salix glaucu and vaccinium uliginosum or with graminoids like kobresia myosuroides. between the slopes there are vast plains with grassland, fens and bogs. kangerlussuaq is the traditional calving area of the isortoq population (thing 1984). the study area lies within 10 to 15 km from the international airport in kangerlussuaq and helicopters often pass the area. the study area was a caribou reserve from 1967 to 1995; hunting has been permitted since 1996. though hunting pressure is low here, it is higher than in the southern study area. the number of caribou killed at the kangerlussuaq study site is about double the number killed at the akia study site (hangaard, pers. comm.). more dators and to provide the background data for over, kangerlussuaq is visited in summer by assessing possible effects on caribou if mineral hikers: in this area caribou encounter humans activities in calving areas are approved. relatively frequently. f i g . 1 . study sites (indicated by arrows) and range of the lsortoq population to the north and the akia population to the south. study areas study locations and ranges of herds studied are shown on fig. 1 . studies were performed within an area of approximately 100km2 at each study location. although natural large predators are not present in the two study sites, sporadic predation of calves by foxes and ravens may occur. akia and tasersuaq are situated in the ranges of the akia population (thing & falk 1990). akia has a rich cover of lichens, while almost no lichens are found tasersuaq, in the north-eastem part of this study area. the topography is moderately hilly, with relatively short viewing distances. tasersuaq lies within the calving areas while it is assumed that only sporadic calving occurs in akia (cuyler & linnell, unpubl. data). both a k a and tasersuaq are rarely visited by humans apart from a few hunters in august and september. though traditional hunting has occurred in the area for centuries, the pressure is low. methods studies were performed 1) during calving in early june 1997, 2) in late july and early august 1997, and 3) after the hunting season in late september 1998 (table 1). caribou groups were approached on foot. approach to the group was initiated by slowly walking in a straight line towards it until flight actually took place. when caribou are first disturbed they show signs of awareness and fright by raising their heads, raising their tails and jumping (de vos 1960). the initial flight is often followed by curiosity behaviour, where the disturbed animal circles around the intruder to catch the scent. during calving care was taken to avoid provoking panic reactions. stops were made for each distance measurement. distances were measured by a laser range finder (leica 7 x 42 bda, geovid). parameters recorded during each encounter with caribou in the study are summarized in table 2. 84 responses of west greenland caribou to the approach of humans on foot table 2 . data recorded at each encounter with caribou during the study parameter date and time temperature insect harassment wind direction wind speed distance vegetation type topography group size group type sighting distance fright threshold distance flight threshold distance run distance run direction curiosity distance descriptionhemarks all study periods were characterized by relatively stable weather conditions. subjectively judged as none, low, o r high based on observations of behaviour associated with avoidance recorded as: none; blowing against the sides of the animals; blowing from the caribou to the observer; recorded as 0, light-brisk, or brisk. the distance from observer to the group was recorded from first observation. recorded as one of the following: dwarf shrub heath without lichens, fell field, golf green, grassland, recorded as flat, hilly or sloping. the total number of individuals. groups were categorized as follows: one individual = single; 2-15 of insects such as mosquitoes, oestrid flies and nostril flies. or blowing from the observer to the caribou. lichen heath, snow patch and snow. individuals = small; 1 6 2 5 individuals = large; and >25 individuals = extra large. data treatment was performed for two categories: single individuals and groups of two or more. recorded as “calf’ if there were one or more calves in it, as “female” if it included adult females but no calves, and as “male” if there were only males in the group. distance where one or more caribou becarhe aware of the researcher either by sight or smell; often identical with the fright threshold distance and in some case> also with the flight threshold distance. distance between caribou and approaching researcher where one or more individuals showed the first sign of fright. distance between the researcher and the group when all individuals ran away. distance from the point where one or more individuals took flight to where the group stopped and took recorded as directly away from the researcher relative to his direction of approach, sideways relative to distance covered by caribou exhibiting curiosity behaviour; the closest approach was also recorded. up another activity; often difficult to measure as the groups often disappeared behind hills. the direction of researcher’s approach, or closer to researcher. these parameters included: “sighting distance”, the distance between an approaching person and the caribou when the animals first showed signs of being aware of the researcher; “fright threshold distance,” the distance between the approaching person and the caribou at their first sign of fright; “flight threshold distance”, the distance between the researcher and the caribou when they began to move off; “run distance”, the distance the caribou ran; and “curiosity distance”, the distance covered by animals exhibiting curiosity behaviour. prior to statistical analysis of the data, a shapiro-wilk test was performed to test for normal distribution. the test indicated that distance data should be logarithmically transformed to achieve normal distribution and variance homogeneity. each of the variables of fright threshold distance, flight threshold distance and run distance were analysed in one model by a glm procedure (sas 1989) for the effects of the following parameters: season, locality, group type, group size, wind direction, insect harassment, vegetation type, topography and interactions. parameters with insignificant effects were removed from the model and the model was run again. it could b e expected that the parameter locality would be auto-corre lated with vegetation type and topography. there fore the model was run initially without locality. neither vegetation type nor topography had significant effects. these parameters were then removed and substituted with locality which had significant effects in some cases, indicating that locality was an important factor which could be related to differences in behaviour among caribou from the two localities. means were compared by a bonferroni means test and least square means, and 95% confidence levels were computed. results sighting distance: group size and locality were significantly correlated with the distance at which caribou became aware of the approaching person (table 3). groups became aware of the researcher earlier than solitary individuals. in the isortoq population, caribou became aware of the research er earlier than those in the akia population. a a s t r u p 2000: polar research 19(1), 83-90 85 table 3. sight distance for group types and localities. upper 95% lower 95% mean confidence limit confidence limit significance group 188.7 169.9 207.5 0.0001 single 132.3 108.2 156.3 isortoq pop. 190.0 169.3 2 10.7 0.0139 nuuk 156.4 132.5 180.4 t table 4 . flight threshold distances for single individuals/groups and for populations ~~~ ~~~ ~ upper 95% lower 95% mean confidence limit confidence limit significance group 145.6 159.9 132.6 0.0001 isortoq pop. 129.5 147.0 114.0 0.0108 single 93.4 111.3 78.3 akia pop. 103.6 118.4 90.6 fright threshold distance: both season (p = 0.0389) and group size (p = 0.0005) had signifi cant effects on the fright threshold distance and there was significant interaction between season and group size (p = 0.0074) (fig. 2 ) . generally fright threshold distance was shortest for single individuals. there was no clear pattern in relation to season. flight threshold distance: both group size and locality had significant effects on flight distance (table 4). flight distances were shortest for single individuals in the akia area. run distance: the effect of group size on run distance was tested for several group size 250 i i 1 1 i 'p==l 50 calving calving after hunt after hunt summer summer gmup single grbup single group single f i g . 2. fright threshold distance (m) for seasons and for single individuals and groups (both sexes and populations). 95% confidence intervals are indicated. categories. only the distinction between singles and groups had significant effects. the analysis was then concentrated on these two categories. group size and season had significant effects on the run distance (table 5). solitary individuals ran significantly shorter distances than groups. run distance was significantly longer during calving than in summer and following hunting. curiosity behaviour: none of the recorded par ameters had a significant effect on the curiosity distance, which was on average 142.6 m (105 observations; lower and upper 95% confidence limits 128.5 m and 156.7 m, respectively). sig nificant differences between localities (table 6) were found after hunting (p = 0.0482) where relatively fewer caribou in the akia population were curious than in kangerlussuaq. differences between male and female groups were not significant. in a k a , calf groups exhibited curios ity behaviour significantly less frequently than both female (p < 0.003) and male groups (p < 0.036) while in kangerlussuaq only the difference between calf and male groups (p < 0.052) was significant. comparison between seasons (table 7) showed that in the a k a population there were significantly fewer curiosity events during calving than in summer (p = 0.0089). the proportion of curiosity events was also smaller during calving than after hunting although this was not significant. in the isortoq population there were significantly fewer curiosity events after hunting than in summer 86 responses of west greenland c a r i b o u to the approach of h u m a n s on foot table 5. run distances for various seasons and group sizes, upper 95% lower 95% mean confidence limit confidence limit significance calving 146.6 186.8 115.1 summer 92.0 114.5 13.9 0.0049 after hunt 98.4 125.9 76.8 single 93.0 124.6 69.4 0.0134 group 129.9 148.7 113.4 (p < 0.0107). there were also fewer curiosity events in this population after hunting than during calving, but the difference was not statistically significant. immediate response: with the exception of male groups in the akia population, about 90% of encounters resulted in an immediate response: the individual responded by fright or flight as soon as it discovered the intruder, i.e. sighting distance equalled flighttfright threshold distance (table 8). male groups in the akia population responded immediately in only 57% of the encounters. this is significantly different than the other group types in the akia population (p <0.049). other parameters: no significant effects on fright threshold and flight threshold distances were recorded for vegetation, topography, wind direc tion, wind speed and level of insect harassment. summing up 0 generally, groups of caribou had longer fright indicating greater vigilance than solitary ani mals. 0 groups with calves were generally more vigilant than female and male groups, while there was no difference between female and male groups. this pattern was most clear in the akia population. 0 the frequency of curiosity behaviour indicated that caribou were less vigilant in the akia threshold, flight threshold and run distances table 6. frequency of curiosity behaviour in relation to group type and population. calf female male lsortoq pop. 32.2 47.1 54.5 akia pop. 29.4 68.0 54.1 population than in the isortoq population after the hunting, while there were no locational differences during the other seasons. 0 caribou in the akia population are most vigilant during calving, while in the isortoq population the highest vigilance was found after hunting. discussion greenland is still a relatively pristine environment, largely undisturbed by human activities and lacking natural large predators. it was expected that under these circumstances differences would be detectable in the reactions of greenland caribou compared with caribou elsewhere. boving & post (1 997) reported that greenland caribou displayed less vigilance during feeding and adopted a vigilant posture less often than caribou in alaska. they postulated that this was an adaptation to the absence of natural predators. in the study reported upon here, caribou showed weak responses to mild provocations but in almost all cases a reaction was 70% of the encounters, flight threshold distances were about 95 m, and mean run distances were between about 95 m and 145 m. elicited. curiosity behaviour w a s seen in nearly table 7. frequency of curiosity behaviour expressed as a percentage of encounters, in relation to season and locality. in the a k a population the proportion of curiosity events was significantly lower (p < 0.0089) during calving than i n summer. in the isortoq population the proportion of curiosity events was significantly lower (p < 0.0107) during after hunt than in summer. comparisons between localities gave sig nificantly different proportions after hunting, where the proportion was lowest in the isortoq population (p < 0.0482). calving summer after hunt isortoq pop. 32.0 52.5 26.2 akia pop. 35.4 64.7 50.0 aastrup 2000: polar research 19(1), 83-90 87 table 8. percentage of immediate responses (when the caribou responded with fright or flight at the same distance as they discovered the intruder), broken down by population and group type. calf female male isortoq pop. 89 88 82 akia pop. 91 88 57* *statistically significant result. among reindeer in southern norway, eftestal (1998) found flight threshold distances between l l o m and 190m, and run distances from ca. 200m to almost 5 0 0 m both greater than we observed in greenland. in svalbard fright thresh old distances varied between approximately 100 m and 160 m, flight threshold distances between’ about 5 0 m and 140m, and run distances from about 8 0 m to more than 300m (colman & jacobsen 1996). generally, greenland caribou fright reactions were similar to svalbard reindeer. this probably reflects the similar histories of the two populations, both having existed for an extended period without large predators and with little hunting (see also klein 1980). in this study, the highest vigilance levels as gauged by fright threshold, flight threshold and run distances occurred in groups with calves during calving and post-calving . in canada’s barren grounds de vos (1960) made similar observations. vigilance during calving is probably inherent in caribou and serves to protect calves from predators (de vos 1960; bergerud 1974; dau & cameron 1986). on the other hand, expenditures of energy should be minimized when caribou are nutritiously stressed following winter and when females are rearing calves. in an area without large natural predators, as in greenland, there is currently no obvious advantage in running long distances during any period. it could, however, be an adaptation to avoid hunters. caribou that are heavily hunted and/or preyed upon by natural predators can be expected to show high vigilance, while caribou not hunted or preyed upon would be expected to show mild reactions and low levels of vigilance (see reimers & kolle 1988). this study found that immediately follow ing hunting, response to approaching humans was similar to that at calving time. indeed, in the isortoq population vigilance was even higher just after hunting than during calving. (it is also possible that the behaviour of caribou in this post-hunting period is influenced by the approach ing rutting period.) of the animals in the two study areas, caribou from the akia population exhibited less curiosity (and had shorter flight threshold distances) when confronted by the approaching researcher. in the a h a population curiosity was lowest in groups with calves and during calving. the curiosity rate increased in summer and decreased slightly after hunting. the small size of the decrease can be accounted for by the low level of hunting in this area, which is difficult to reach from the coast. in the isortoq population, where curiosity was higher than in the akia population, curiosity levels were similar during calving and during summer but after the hunt the curiosity rate fell below the level during calving. this can be interpreted as an adaptation to hunting by humans. however, this lesson seems to be short-lived, as the curiosity rate increased during summer. environmental regulation of activities in calving areas during calving this study has provided: 1) documentation that greenland caribou normally respond by fright or flight when approached by humans and behave much like caribou in e.g. norway and svalbard; 2) support for the assumption that caribou in green land are more sensitive during calving than in summer and to some degree also after hunting; and 3) documentation that the effect of disturbance, measured as frequency and strength of energy consuming reactions, is greater during calving than in summer and in autumn after hunting. negative impacts on caribou of disturbances include reduced feeding and resting time, avoid ance of sites of disturbance, increased risk of detection by predators and injuries related to severe harassment. bradshaw et al. (1997) sug gested for woodland caribou in alberta that increased movement may result in higher energy expenditure during winter and that disturbed caribou may switch habitat type for cover or escape terrain. they recommended limiting total disturbance during winter instead of restricting timing of industrial activity as a mitigating procedure. calving areas may merit particular care. car ibou usually calve in more or less well-defined calving grounds (miller & broughton 1973). these calving grounds have long been considered critical habitats for large migratory caribou herds 88 responses of west greenland caribou to the approach of humans on foot in north america (kelsall 1968; thomas 1969; klein 1991; mccabe 1994). the international porcupine caribou board (1995) ranked calving grounds highest among sensitive habitats for the porcupine herd in alaska and yukon. in greenland, high fidelity to specific calving grounds has been documented for four herds: one with calving grounds north-east of kangerlussuaq (thing 1984); one south of the ameralik fiord, which is south of nuuk (aastrup 1986); one north of lake. tasersuaq, which is north of the nuuk fiord (cuyler & linnell, unpubl. data; aastrup, unpubl. data.); and one in the area of nassuttuup nunaa (aastrup, unpubl. data). calving also occurs in the qorqut area in the ranges of the former domestic reindeer herd in itinnera and among the domestic reindeer in isortoq in southern greenland (lund et al.). calving may occur in other localities as well, some of which may be important. environmental guidelines (gbp 1998) for mineral exploration in greenland stipulate that mineral activities in calving grounds during calving require approval by the greenland bureau of minerals and petroleum (gbp) while tourism and other kinds of public access to the calving grounds is not regulated. although not spelled out in the regulations, the reason for protecting calving caribou is the risk of negative effects on calf survival via harassment induced injuries, de creased time for food intake, increased time of energy consumptive activities, and displacement from optimal foraging areas. as confirmed by the present study, it was assumed that groups with calves were more sensitive to disturbance than other groups and they were most sensitive to disturbance during calving. this study indicated that a single encounter between a human and a group of caribou seems to have little lasting impact. there is little doubt, however, that very close contact such as close photographic efforts or helicopter landings would impose a high risk of injuries to newborn calves. and it must be noted that even minor disturbances if repeated often enough may affect feeding time and energy balance negatively, and may displace animals from optimal foraging areas (cameron et al. 1992). it seems probable that small-scale activities with one or two persons moving around in the area without intent to disturb the caribou will have a minimal effect, but activities on a larger scale with much traffic and use of all terrain vehicles could cause displacement of caribou to less optimal sites a n d or result in competition for food resources. in the future, special attention should be paid to caribou calving grounds in greenland, with continued emphasis on the requirement of ap proval of all mineral exploration and development activities during calving time. acknowledgements. i wish to thank jonathan colman and sindre eftestol for inspiration and willingness to help during the initial phase of the study. josephine nymand and christine cuyler are thanked for good companionship in the field. two anonymous reviewers are thanked for valuable comments and suggestions. the study was funded by the danish environ mental protection agency. references aastrup, p. 1986: rensdyrundersbgelser ved vandkraftprojekt kangerluarssunnguaq/bukse~ord, nuuwgodthiib 1984485. (caribou studies related to the kangerluarssunnguaq/bukse fiord hydropower project in nuuwgodthdb 1984-85.) copen hagen: gronlands fiskeriog milj@undersogelser (green land’s fisheries and env.). bergerud, a. t. 1974: the role of the environment in the aggregation, movement, and disturbance behaviour of caribou. in v. geist and f. walther (eds.): the behaviour of ungulates and its relation to management. vol. 2. iucn publ., new ser. 24,552-584. morges, switzerland. int. union for the conservation of nature. boving, p. s . & post, e. 1997: vigilance and foraging behaviour of female caribou in relation to predation risk. rangifer 17(2), 55-63. bradshaw, c. i. a., boutin, s. & hebert, d. m.1997: effects of petroleum exploration on woodland caribou i n northeastern alberta. j . wildl. manage. 6/(4), 1127-1 133. cameron, r. d., reed, d. j., dau, j . r. & smith, w. t. 1992: redistribution of calving caribou in response to oil field development on the arctic slope of alaska. arctic 45(4), 338-342. colman, j. e. & jacobsen, b. w. 1996: summerfright distances of svalbard reindeer (rang f i r turundu3 plaryrhyncus) after disturbance by humans on foot. the frequency of untlerless females among svalbard reindeer (rangifer tarandus platyr hyncus). cand. scient. thesis, dept. of biology, university of oslo. dau, j . r. & cameron, r. d. 1986: effects of a road system on caribou distribution during calving. rangifer, spec. issue i, de vos, a. 1960: behaviour of barren ground caribou on their calving grounds. j . w i l d manage. 24(3), 250-258. eftestol, s . 1998: fright behaviour in norwegian wild reindeer (rangifer tarandus tar-andus) after disturbance by humans on foot o r skis. cand. scient. thesis, dept. of biology, university of oslo. gbp (bureau of minerals and petroleum) 1998: rules f o r f i e l d work and reporting regarding mineral resources (excluding hydrocarbons) in greenland. nuuk: government of green land, bureau of minerals and petroleum (gbp). international porcupine caribou board 1995: sensitive habitats 95-101. aastrup 2000: polar research 19(1), 83-90 89 of the porcupine caribou herd. report from the porcupine caribou technical committe. kelsall, j. p. 1968: migratory barren-ground caribou of canada. ottawa: canadian wildlife service. klein, d. r. 1 9 8 0 reactions of caribou and reindeer to obstructions reassessment. in e. reimers et al. (eds.): proceedings of the second international reindeedcaribou symposium, rbros, norway, 1979. pp. 5 19-527. trondheim: direktorat for vilt og ferskvannsfisk (directorate of game and freshwater fish). klein, d. r. 1991: caribou in the changing north. appl. anim. behav. sci. 29, 279-291. mccabe, t. r. 1994: assessing values of arctic wildlife and habitat subject to potential petroleum development. lands. urban plan. 28, 33-45. miller, f. l. & broughton, e. 1973: behaviour associated with mortality and stress in maternal-filial pairs of barren-ground caribou. can. field-nut. 87, 21-25. reimers, e. & kolle, k. 1988: jaktens betydning for villreinens aktivitetsbudsjett og konsekvenser for dyrenes vekst og kroppst~arrelse. (effects of hunting on caribou activity budgets and its consequences for individual growth and body size.) villreinen 2, 5-6. sas 1989: sas/stat user's guide. version 6. fourth edition. voi. i . c q , nc: sas institute inc. thing, h. 1984: feeding ecology of the west greenland caribou (rangifer tarandus groenlandicus) in the sisimiut-kanger lussuaq region. dan. rev. game biol. 12(3). thing, h . & falk, k . 1990: status over rensdyrbestandene i vestgrgnland mellem nassuttuup og paamiut sermiat. marts-april 1990. (status of caribou populations in west greenland between nassuttuup and paamiut sermiat. march-april 1990.) teknisk rapp. 19. grenlands hjernrnes tyre, mil& og naturforvaltning (greenland's home rule, env. and nature management.) thomas, d. c. 1969: population estimates of barren-ground march to may, 1967. can. wildl. serv. rep. ser. 9. 90 responses of w e s t greenland caribou t o t h e approach of humans on foot doi:10.3402/polar.v33.21417 r e s e a r c h / r e v i e w a r t i c l e selected elements in surface waters of antarctica and their relations with the natural environment arkadiusz nędzarek,1,2 agnieszka tórz1 & arkadiusz drost1 1 department of aquatic sozology, west pomeranian university of technology in szczecin, k. królewicza 4, pl-71-550 szczecin, poland 2 department of antarctic biology, polish academy of sciences, ustrzycka 10-12, pl-02-141 warsaw, poland keywords antarctic surface waters; total and dissolved elements; baseline elements values; anthropogenic metal contamination. correspondence arkadiusz nędzarek, department of aquatic sozology, west pomeranian university of technology in szczecin, k. królewicza 4, pl-71-550 szczecin, poland. e-mail: arkadiusz.nedzarek@zut.edu.pl abstract the aim of the study was to specify the concentration of selected chemical elements in surface waters of king george island, off the western coast of the antarctic peninsula. the research encompassed six streams, a lake and an artificial water reservoir located on the western coast of admiralty bay. measured hydrochemical parameters included ph, conductivity, total dissolved solids (tds), and total and dissolved forms elements such as al, co, ni, cu, zn, cd, pb, mn, fe, as and se. the values of ph, conductivity and tds had the following ranges: 6.09�8.21, 6.0�875 ms cm�1 and 7.0�975 mg/l, respectively, and were typical for surface waters of antarctica. wide disparities were discovered regarding concentrations of the investigated elements, ranging from b0.01 mg/l for cd to 510 mg/l for fe, and differing from one water body to another. the investigated elements are discussed with reference to environmental conditions and anthropogenic factors. concentrations of total and dissolved forms of elements are considered in connection with the composition of soil in their surroundings and with atmospheric deposition, mostly such as that took place locally. the increased levels of pb and zn concentrations in the immediate proximity of a research station suggested anthropogenic contamination. one of the results of human impact is a change in the concentrations of trace metals in surface waters of the earth; therefore it is advisable to conduct research in parts of the world located far from industrialized and populated areas. the isolation of antarctica provides an opportunity to study surface waters in their original state and to treat them as a reference point with respect to other areas of the earth (préndez & carrasco 2003). it is a matter of particular importance to recognize the qualitative composition of surface waters in regions characterized by progressive deglaciation. in antarctica, the antarctic peninsula is such a region. for four decades the results of climate warming, including melting glaciers and the occurrence of areas free from ice both alongside the coast and inland, have been observed there (martianov & rakusa-suszczewski 1990; king 1994; skvarca et al. 1998; birkenmajer 2002; cook et al. 2005). an especially important research area is king george island, one of the south shetland islands. it is one of the most populated areas of the maritime antarctica, where deglaciation processes have been observed since the 1970s (martianov & rakusa-suszczewski 1990; birkenmajer 2002). this provides an opportunity for conducting research both in an environment subject to heavy human impact (e.g., fildes peninsula) and in an environment subject to almost no human impact. the aim of our study was to discuss the composition of selected elements occurring in surface waters of the western coast of admiralty bay, king george island, with respect to basic hydrochemical indicators (ph, conductivity, dissolved solids) and to focus on mechanisms determining the presence of the elements in suspended and dissolved fractions. the problem of origin of the studied elements from natural and anthropogenic to access the supplementary material for this article, please see supplementary files under article tools online. polar research 2014. # 2014 a. nędzarek et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 21417, http://dx.doi.org/10.3402/polar.v33.21417 (page number not for citation purpose) http:/www.polarresearch.net/index.php/polar/rt/suppfiles/21417/0 http:/www.polarresearch.net/index.php/polar/rt/suppfiles/21417/0 http://www.polarresearch.net/index.php/polar/article/view/21417 http://dx.doi.org/10.3402/polar.v33.21417 sources was considered, taking into account air pollutants brought from the island and/or neighbouring continents by the wind. material and methods the studied surface water bodies are located on the western coast of admiralty bay (king george island, south shetland islands, antarctic peninsula; fig. 1). admiralty bay is situated in the sub-polar climatic zone, characterized by strong winds, high air humidity, total precipitation exceeding 505 mm, striking changeability of daily weather and considerable fluctuations in air temperature*from �32 to �168c (kratke & wielbińska 1981; styszyńska 1990; marsz & styszyńska 2000). since 1977, an all-year polish station named after h. arctowski has functioned in the area. during this period, progressive deglaciation was observed off the coast of admiralty bay, north of ecology glacier (the area covered by this glacier in 1979 is shown in fig. 1). the research encompassed six streams: petrified forest creek (pfc), ornithologists creek (oc), czech creek (cc), a stream running along the border of ecology glacier (eg), vanishing creek (vc), a stream running across the wróbel valley (wv) and lake wujka (lw), as well as an artificial drinking water reservoir (dwr) which belonged to the research station (fig. 1). water samples were collected from the sources and mouths of streams, and in the case of oc additional samples were collected midstream. as for lw and dwr, samples were collected from the central part of the reservoirs at a depth of 20 cm below the water surface. samples were collected between january and march 2005. we used procedures of water sample collection, storage and analysis that minimized the possibility of sample contamination. polyethylene bottles and their caps utilized for storing samples had been cleaned with 2% hno3, rinsed with milliq purified water (18.2 mv) and dried at a temperature of 30�358c. the dissolved fractions were analysed in 500 ml samples filtered through a 0.45 mm polypropylene membrane that had been purified with ultrapure water and 150 ml samples of tested water. water samples (both filtered and unfiltered) were preserved by adding 2 ml of hno3 to lower the ph value below 2, frozen and transported to poland, where they were subject to further analysis according to the methodology specified by the american public health association (apha 1995). in all cases, al, co, ni, cu, zn, cd, pb, mn, fe, as and se were quantified by an elan drc-e inductively coupled plasma-mass spectrometer (icp-ms; perkin elmer, waltham, ma, usa). all analyses were carried out in duplicate. certified model solutions produced by tusnovics instruments (krakow, poland) were used to assess measurement precision and construct fig. 1 location of the research area on the western coast of admiralty bay featuring sampling sites (nos. 1�15) where surface water samples were collected: 1 lake wujka (lw); 2 drinking water reservoir (dwr); 3, 4 petrified forest creek (pfc); 5, 6, 7 ornithologists creek (oc); 8, 9 czech creek (cc); 10, 11 stream flowing along the border of ecology glacier (eg); 12, 13 vanishing creek (vc); 14, 15 stream flowing across the wróbel valley (wv). selected elements in surface waters of antarctica a. nędzarek et al. 2 (page number not for citation purpose) citation: polar research 2014, 33, 21417, http://dx.doi.org/10.3402/polar.v33.21417 http://www.polarresearch.net/index.php/polar/article/view/21417 http://dx.doi.org/10.3402/polar.v33.21417 calibration curves. spectral interferences were corrected with the help of merck’s (whitehouse station, nj, usa) internal model: 103 rh (10 mg/l rh[no3]3 in hno3 2�3%). the precision of the analytical procedures (calculated as standard deviations of triplicates) was higher than 10%. detection levels (in ng/l) amounted to: al 0.09; co 1.0; ni 1.2; cu 0.5; zn 0.3; cd 0.08; pb 0.06; mn 0.78; fe 0.20; as 0.9; and se 1. prior to conducting the series of measurements, the icp-ms was properly optimized both in the standard operation mode and in the drc-e mode, using appropriate perkin-elmer optimizing solutions. basic optimization criteria included achieving maximum sensitivity to respective chemical elements, the slightest possible signals for oxides (e.g., ceo � ) and doubly charged ions (e.g., ba �� ) and the lowest possible background values. simultaneously, blank tests were performed using milliq (18.2 mv) water (tests were performed for filtered and unfiltered water). concentrations of studied metals indicated in the blank tests were taken into account in the final results for respective metals. conductivity and total dissolved solids (tds) were measured with a lf197 conductivity meter (wtw weilheim, germany) and ph was measured with a hi 9025 ph meter (hanna instruments, woonsocket, ri, usa). those parameters were measured immediately in the field while collecting water samples, with an accuracy of up to 0.0 for tds and conductivity and up to 0.00 for ph. subsequently, statistical analysis was applied to the obtained results, conducted with the aid of statistica 10.1 software (statsoft inc. 2011). pearson’s linear regression was calculated for a�0.05 and principal component analyses (pca) were conducted. pca analyses were performed using the mean values for each variable and water body. standardized values of the chemical parameters were taken into account. results the ph range and average ph values for water, as well as the conductivity and tds values, can be found in table 1. the ph ranged from 6.09 to 8.21, while the average ph value amounted to 7.67. toward the mouth of the stream, and away from its source, ph tended to increase slightly. the highest difference between water ph values between particular research sites was noted for oc, and at the same time the lowest ph was noted at its source (fig. 2). conductivity values ranged from 6.0 to 875 ms/cm and tds values ranged from 7.0 to 975 mg/l, with averages of 170.7 ms/cm and 190.7 mg/l, respectively. the lowest values of the aforementioned indicators were observed in water samples collected from eg: they were half the average values for the remaining streams. the highest conductivity and tds values were recorded in the waters of lw, exceeding the corresponding values in the other freshwater reservoirs of thomas point oasis by about three times. increasing conductivity and tds values were also noted while table 1 range and average values of the investigated physicochemical indicators in surface waters of the western coast of admiralty bay. water body a n b statistics ph conductivity ms/cm total dissolved solids mg/l eg 8 range 6.88�7.79 6.0�158.7 7.0�177.0 mean 7.48 72.40 80.5 wv 8 range 7.30�8.02 38.7�232 43.0�258.0 mean 7.73 122.5 136.5 cc 8 range 7.10�7.99 132.0�209.0 159.0�233.0 mean 7.87 160.1 180.3 vc 8 range 7.70�7.93 118.8�289.0 133.0�322.0 mean 7.83 172.6 192.6 pfc 8 range 7.80�8.02 156.1�202.0 174.0�227.0 mean 7.90 179.5 200.1 oc 12 range 6.09�7.94 31.3�226.0 35.0�254.0 mean 7.28 167.6 187.5 dwr 4 range 7.66�7.96 143.7�178.8 160.0�201 mean 7.81 165.6 184.8 lw 4 range 7.66�8.21 399.0�875.0 446.0�975.0 mean 7.90 580.0 647.0 mean 7.67 170.7 190.7 a sampled waters are abbreviated as follows: a stream flowing along the border of ecology glacier (eg); a stream flowing across the wróbel valley (wv); czech creek (cc); vanishing creek (vc); petrified forest creek (pfc); ornithologists creek (oc); drinking water reservoir (dwr); lake wujka (lw). btotal: 60. fig. 2 variability of ph at sampling stations at ornithologists creek: stream mouth (5); middle part of the stream (6); and stream source (7). a. nędzarek et al. selected elements in surface waters of antarctica citation: polar research 2014, 33, 21417, http://dx.doi.org/10.3402/polar.v33.21417 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21417 http://dx.doi.org/10.3402/polar.v33.21417 moving away from the source towards the stream mouth, similar to oc (fig. 3). supplementary tables s1 and s2 provide concentration range, mean values, absolute standard deviation for the entire population and variation coefficient for total concentrations and dissolved fractions of the studied elements. concentrations of total elements ranged widely between b0.01 mg/l in the case of cd and 510 mg/l in the case of fe; both concentrations were recorded in water samples collected from the stream running along eg (supplementary table s1). with regard to mean values, total elements could be divided into three groups. the first group included elements with the highest concentrations, such as al and fe, with average concentrations of 17.4 and 67.1 mg/l, respectively. those elements showed a high level of interdependence, and the calculated correlation coefficients were statistically significant: r �0.93 (table 2, fig. 4). the pca analysis also indicated the existence of a strong mutual dependence between the two elements (fig. 5). the second group included cu, zn, pb and mn, with average concentrations amounting to 1.19, 10.59, 5.55 and 9.08 mg/l, respectively. within this group, significant correlations were observed between cu and zn, cu and pb, cu and mn, as well as between zn and mn. the values of pearson’s correlation coefficient amounted to 0.67, 0.27, 0.64 and 0.30, respectively (table 2). finally, the third group included elements characterized by the lowest concentrations: co, ni, cd, as and se, with average concentrations of 0.16, 0.56, 0.48, 0.57 and 0.08 mg/l, respectively. no statistically significant correlations were discovered between elements in this group (table 2). however, significant correlations were discovered between co and such metals as mn and fe (r �0.69 and 0.31, respectively); a correlation was also discovered between pb and ni (r �0.86) (table 2). among studied elements, in the case of co, cu and mn, significant inversely proportional correlations with water ph were discovered, whereas for the remaining metals such correlations were not statistically significant and the directions of correlations varied. with regard to conductivity and tds, statistically significant correlations were noted for mn and se (table 2). in the case of most studied metals, higher concentrations were discovered in water samples collected from stream mouths in comparison to those collected from stream sources (table 3). statistical analysis of the dependence between chemical element concentrations and the distances of the studied streams revealed mostly positive correlations. statistically significant correlations were identified only for mn and se (r �0.29 and 0.38, respectively). for cd and as, the dependence on distance was inversely proportional (table 2). pca analysis was applied in order to find dependencies between the studied chemical elements and water bodies, which allowed for reducing 11 variables to three principal components while retaining over 98% of the total variance. the pca analysis led us to distinguishing two groups of water reservoirs. the first group included oc and lw: water samples collected from those water bodies showed similar concentration levels of ni, cu, zn, cd, pb, mn, fe and as. the second group comprised the remaining studied reservoirs (fig. 6). in this group, large disparities were observed from one reservoir to another with respect to concentrations of elements, so it was impossible to break the group into subgroups. concentrations of dissolved elements (supplementary table s2) may also be described as divisible into three groups. the highest average concentration of the dissolved fraction was recorded in the case of fe, amounting to 17.5 mg/l. the second group, characterized by average concentrations of dissolved fractions included al, zn, cd, pb and mn (5.1, 3.27, 1.95 and 2.35 mg/l, respectively). finally, the third group, with the lowest concentrations of dissolved fractions included such elements as co, ni, cu, cd, as and se (0.05, 0.23, 0.45, 0.08, 0.26 and 0.13 mg/l, respectively). the concentrations of dissolved elements were lower in comparison to total concentrations by the average values of 19% for se, 29% for as, 49% for pb, 50% for cd, 57% for mn, 59% for fe, 61% for co and ni, 65% for al and 67% for cu. fig. 3 variability of total dissolved solids (tds) at sampling stations at ornithologists creek: stream mouth (5); middle part of the stream (6); and stream source (7). selected elements in surface waters of antarctica a. nędzarek et al. 4 (page number not for citation purpose) citation: polar research 2014, 33, 21417, http://dx.doi.org/10.3402/polar.v33.21417 http://www.polarresearch.net/index.php/polar/rt/suppfiles/21417/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/21417/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/21417/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/21417/0 http://www.polarresearch.net/index.php/polar/article/view/21417 http://dx.doi.org/10.3402/polar.v33.21417 discussion the levels of ph, tds and conductivity recorded in the course of the study were typical for antarctic freshwaters. similar values of these parameters had been given by: howard-williams et al. (1989), sheppard et al. (1997), vinocur & unrein (2000), elster & komarek (2003) and toro et al. (2007). the ph of freshwater in antarctica is affected by such factors as primary production, which increases ph, and the infiltration of ornithogenic soils, which lowers ph. in the study discussed here, an acidic ph level was observed in the water sample collected at the mouth of oc (fig. 2). similar results for the same stream were obtained by elster & komarek (2003), who posited that they were due to the decomposition of penguin droppings in the catchment area of the stream. the stream flows through ornithogenic soils and, as has been pointed out by juchnowicz-bierbasz (1999) and juchnowicz-bierbasz & rakusa-suszczewski (2002), waters infiltrating this type of soils are acidic. the increased ph levels in the remaining reservoirs might be attributable to primary production. water in antarctic streams is characterized by low buffer capacity, so ph can increase even with a very low rise in primary production (toro et al. 2007). antarctic streams are supplied by meltwater from glaciers and permafrost, as well as melting snow and rain, and are therefore characterized by low tds concentrations, which we observed in this study (the lowest tds and conductivity were recorded in eg). however, due to the effect of sea aerosol, the tds and conductivity table 2 values of pearson’s correlation coefficient (r) regarding total concentrations of the investigated elements, physicochemical indicators and distance in the investigated surface waters. an asterisk indicates statistical significance at pb0.05. al co ni cu zn cd pb mn fe as se ph conductivity co 0.49* � ni �0.07 0.06 � cu 0.25 0.58* 0.45* � zn �0.01 0.25 0.22 0.67* � cd �0.11 �0.09 0.24 0.13 0.10 � pb �0.13 �0.04 0.86* 0.27* 0.11 0.07 � mn 0.24 0.69* 0.14 0.64* 0.30* 0.20 �0.04 � fe 0.93* 0.31* �0.02 0.22 0.04 �0.07 �0.08 0.13 � as 0.17 �0.04 �0.24 �0.13 �0.07 �0.09 �0.24 �0.05 0.10 � se �0.14 �0.02 0.14 0.14 0.11 �0.06 0.11 0.29* �0.16 0.14 � ph �0.20 �0.70* �0.02 �0.39* 0.02 0.04 0.02 �0.64* �0.02 0.09 0.18 � conductivity �0.18 �0.06 0.03 0.22 0.10 0.08 0.02 0.33* �0.17 �0.15 0.68* 0.21 � total dissolved solids �0.18 �0.06 0.03 0.22 0.10 0.08 0.02 0.33* �0.17 �0.15 0.68* 0.21 1.00* distance 0.02 0.22 0.26 0.24 0.22 �0.08 0.24 0.29* 0.00 �0.22 0.39* �0.11 0.23 fig. 4 the correlation between aluminium and iron in the investigated surface waters of the western coast of admiralty bay (statistically significant correlation coefficient). fig. 5 the principal component analysis (pca) results regarding all investigated metals. taking into account the existing correlations, four groups of metals are distinguished: groups i, ii and iii included metals displaying very strong correlations within each group; group iv included metals which did not display strong correlations within the group. total variation for the first two components equaled 49.87%. a. nędzarek et al. selected elements in surface waters of antarctica citation: polar research 2014, 33, 21417, http://dx.doi.org/10.3402/polar.v33.21417 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21417 http://dx.doi.org/10.3402/polar.v33.21417 may become higher, especially in the littoral zone (caulkett & ellis-evans 1997; toro et al. 2007). according to nędzarek & rakusa-suszczewski (2007), average rainwater conductivity in the fluvial terrace in the lowest location (2 m a.s.l.) on the western coast of admiralty bay equalled 1613 ms/cm. furthermore, the authors proved that the conductivity of atmospheric precipitation (rain and snow) depended on the power and direction of the wind as well as on the season. they noted higher conductivity in atmospheric precipitation during storms, in the precipitation carried by winds blowing in the north�north-west direction, and in the summer season. in the region of the admiralty bay, winds blowing from the north and the north-west prevail during austral summer and are especially powerful in the autumn. sea aerosol could be responsible for the heightened conductivity and tds values in lw that were recorded in our study. according to pociecha (2008), the conductivity of the water in lw was as high as 378600 ms cm�1, while water temperature dropped to �18c. total and dissolved concentrations of the studied elements showed considerable variability and, together with the variation coefficient, were similar to those recorded by other authors discussing heavy metal contents in water bodies of antarctica (e.g., sheppard et al. 1997; préndez & carrasco 2003). for instance, green et al. (2005) showed that during a 49-h study period there was a 13-fold difference regarding fe concentrations and in the case of cd there was a 16.5-fold difference between table 3 a comparison of total elements concentrations (average values) at the mouths and sources of the investigated streams. al co ni cu zn cd pb mn fe as se streams a n mg/l mouths eg 4 47.2 0.24 0.50 1.57 6.90 0.03 2.29 7.44 192.9 0.24 0.10 wv 4 19.3 0.19 0.29 1.04 7.08 0.03 1.16 7.12 73.0 1.18 0.23 cc 4 5.2 0.05 0.29 0.63 7.37 0.04 1.87 1.36 30.6 0.23 0.12 vc 4 12.7 0.08 0.19 0.65 9.93 0.04 1.35 2.01 44.4 0.18 0.19 pfc 4 7.7 0.05 1.58 1.47 11.49 0.25 15.57 1.89 40.6 0.08 0.19 oc 4 18.3 0.55 0.89 4.20 24.74 0.11 5.33 33.9 33.0 0.11 0.19 sources eg 4 14.0 0.18 0.76 1.49 7.97 0.04 3.73 3.69 59.9 0.13 0.05 wv 4 23.7 0.10 0.20 0.98 6.94 0.05 1.02 5.02 66.9 2.08 0.16 cc 4 6.5 0.04 0.23 0.62 6.41 0.02 1.81 1.12 22.0 0.18 0.10 vc 4 10.0 0.06 0.23 0.60 4.56 0.04 1.09 2.08 40.3 0.20 0.18 pfc 4 6.3 0.06 0.83 1.06 10.22 0.18 10.26 1.45 40.6 0.13 0.13 oc 4 9.3 0.10 0.49 1.24 7.61 0.88 3.39 4.75 36.5 0.22 0.10 average mouths 24 18.4 0.19 0.63 1.59 11.26 0.08 4.60 8.96 69.1 0.34 0.17 sources 24 11.6 0.09 0.46 1.00 7.28 0.20 3.55 3.02 44.4 0.49 0.12 a sampled waters are abbreviated as follows: a stream flowing along the border of ecology glacier (eg); a stream flowing across the wróbel valley (wv); czech creek (cc); vanishing creek (vc); petrified forest creek (pfc); ornithologists creek (oc); drinking water reservoir (dwr); lake wujka (lw). fig. 6 results of principal component analysis of (a) dissolved elements and (b) total elements dividing surface waters into two groups: group i included the oc stream and the lw lake while group ii included the remaining streams and the dwr (a � dissolved elements, b � total elements). selected elements in surface waters of antarctica a. nędzarek et al. 6 (page number not for citation purpose) citation: polar research 2014, 33, 21417, http://dx.doi.org/10.3402/polar.v33.21417 http://www.polarresearch.net/index.php/polar/article/view/21417 http://dx.doi.org/10.3402/polar.v33.21417 the highest and the lowest concentration. such results indicated that the metals they studied were exceedingly sensitive to the changes of conditions in the stream. following the conclusions drawn by préndez & carrasco (2003) and green et al. (2005), it can be assumed that in our study the observed high levels of variation regarding concentrations of selected elements were probably due to the effects of local factors and not due to any influences from beyond the island. the analysed elements could have been washed out from surrounding soils by meltwater from the permafrost and melting glaciers, and could also have originated from local atmospheric dust, including the dust brought down from the atmosphere by rainfall and snowfall as a result of changing directions of the wind (e.g., wind-born dust, sea spray). some atmospheric dust might even have originated from burned fuels used for heating scientific stations (loureiro et al. 1992; ikegawa et al. 1997; sheppard et al. 1997; mishra et al. 2004; lu et al. 2011). according to bölter (2011), soils in the studied area are composed of weathered rocks of volcanic origin (mainly basaltic andesites and pyroclastic rocks), as well as a mosaic of sedimentary rocks, similarly to soils in other parts of king george island. there are also ornithogenic soils, believed to cover ca. 70 ha (tatur 1989). as shown in table 4, volcanic rocks and soils of king george island are characterized by metal concentrations exceeding the average concentrations found in the earth’s crust, with cu and mn concentrations being especially high. therefore, the recorded heightened concentrations of the studied elements may be associated with such natural processes as geochemical weathering of volcanic rocks taking place in catchment areas of the studied water reservoirs, and not necessarily with anthropogenic pollution. this is especially plausible for research sites in places where the arctowski station cannot directly affect them. comparing the results of our research with data provided by préndez & carrasco (2003), we found lower concentrations of most elements. higher concentrations were discovered only in the case of pb and mn, while the concentrations of co and al were similar. préndez & carrasco (2003) studied surface waters on fildes peninsula, in the western part of king george island, where an airport and scientific stations belonging to chile, russia, china and uruguay were located. the area is subject to much heavier human impact than where our study took place. as pointed out by campbell et al. (1994), breaking up the surface of soil in antarctica results in releasing water from the melting permafrost. precipitating out while the rising groundwater evaporated, mineral salts have accumulated on the surface of antarctic soils. this phenomenon confirms the existence of a water circulation system transporting dissolved salts. in addition, these salts, which are products of chemical reactions, have a tendency to accumulate in soil until they are washed out by water (ugolini & anderson 1973). as shown by sheppard et al. (1997), areas affected by human activity may be characterized by higher metal concentrations than areas unaffected by such activity. this can be the result of waste storage and releasing solid particles to the atmosphere; such particles can contain, for instance, pb from fuels and zn from used car tyres. anthropogenic activities might be the reason why higher pb and zn concentrations were recorded in drw, lw, pfc and oc, in the immediate proximity of arctowski station. annually, the station burns ca. 100 tonnes of fuel, emitting ca. 0.2 kg yr �1 pb and 0.5 kg yr �1 zn (table 5). research conducted by suttie & wolff (1993) showed very high concentrations of cu, cd, pb and zn in snow samples collected in the immediate proximity of combustion engines. the further away from the source of exhaust gases, the lower were the metal concentrations, and at the distance of 10 km they dropped to the table 4 metal content in soils and volcanic rocks of antarctica compared to metal content in earth’s crust (values in mg/kg, except al and fe in %). matrice al cu fe mn ni pb zn soil near ferraz station a 3.44 44 6.15 442 5.1 11.5 52 soil near lake vanda b � 28 1.0 104 11.2 3.9 24 fildes peninsula c � 129 5.54 1201 44.0 58 81 fildes peninsula d 5.86 122 5.7 923 14.3 15.8 58 volcanic rocks (king george island) e 5.18 111 2.79 1500 12.5 7.7 66 rocks (global average)f 4.77 25 4.32 716 56.0 14.8 65 a santos et al. (2005). bwebster et al. (2003). c carrasco and prendez (1991). d lu et al. (2011). egroeneweg & beunk (1992). f wedepohl (1995). table 5 annual fuel consumption and emission of selected metals resulting from fuel burned at the stations located on king george island (data from mishra et al. 2004). fuel consumed l/yr pb zn cu cd station kg/yr arctowski (poland) 100 000 0.20 0.5 0.1 0.000003 artigas (uruguay) 150 000 0.30 0.75 0.15 0.000005 bellingshausen (russia) 250 000 0.50 1.25 0.25 0.000008 ferraz (brazil) 320 000 0.64 1.6 0.32 0.00001 frei (chile) 1 000 000 2.00 5.0 1.0 0.00003 great wall (china) 250 000 0.50 1.3 0.25 0.000008 jubany (argentina) 240 000 0.48 1.2 0.24 0.000007 king sejong (korea) 273 000 0.55 1.4 0.27 0.000008 total 2 583 000 5.20 12.9 2.6 0.000077 a. nędzarek et al. selected elements in surface waters of antarctica citation: polar research 2014, 33, 21417, http://dx.doi.org/10.3402/polar.v33.21417 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21417 http://dx.doi.org/10.3402/polar.v33.21417 background level. in the case of king george island, exhaust gases should be viewed as resulting from an anthropogenic influence. the island is one of the most heavily populated areas of antarctica, with eight all-year scientific stations and an airport that belongs to the chilean station. as the island is easily accessible and its environment is attractive, the area is frequently visited by cruise ships. the resulting exhaust gas emissions may affect a considerable area of the island, and because the distances between particular stations are rather short, negative effects can be overlapping. the concentration values recorded for most elements analysed by us can be considered close to the geochemical background of the region of antarctica covered by our study. for instance, high cu concentrations in the soils of the antarctic peninsula and king george island are connected with copper mineralization and not with anthropogenic pollution (lu et al. 2011). according to the results of statistical analyses, there are strong correlations between various elements. especially high correlations have been recorded for al and fe, mn and cu, co and mn, and finally for co and fe (table 2), which implies their terrigenous origin, as the rocks and soils of king george island are rich in these metals (table 4). the structure of catchment areas played an important role in the process of shaping physicochemical conditions of the studied water reservoirs. this fact was confirmed by pca analysis (fig. 6). the division of studied water bodies into two groups can be explained by different types of catchment areas characteristic of reservoirs belonging to these two groups. the catchment areas of oc and lw have ornithogenic soils. additionally, breeding colonies of adélie penguins (pygoscelis adeliae) and brown skuas (catharacta antarctica) occur nearby. ornithogenic soils are composed of clays containing secondary aluminous and ferriferous phosphates, and have the capacity to retain elements permanently (tatur 1989). as for the remaining reservoirs, their catchment areas have mainly mineral soils and are hardly affected by the presence of ornithofauna. the observed increase of conductivity, tds and concentrations of selected elements further away from the sources of streams and closer to their mouths is typical for lotic waters, in which dissolved substances tend to accumulate over the years (wetzel 2001). this is particularly notable for major ions, as was shown, for example, for the onyx river by green et al. (2005). in their study, they did not observe homogeneous growth of heavy metal concentrations along the course of the river. similarly, in our study we did not observe uniform accumulation of any of the studied chemical elements along the course of the stream from the source to the mouth. moreover, statistically significant correlations regarding the dependencies between the elements and the distances of the studied streams were discovered only in the case of mn and se. rapid particulate scavenging, recycling from pore waters, and local weathering processes are all likely to contribute to longitudinal variations (green et al. 2005). the lower concentrations of dissolved elements that we recorded indicated the presence of a considerable share of the studied elements in the solid phase. similar dependencies were noted by green et al. (2005), proving that such dependencies were typical for metals in river waters all over the world. it can be assumed, after préndez & carrasco (2003), that the elements were absorbed or complexed on suspended mineral and organic particles. sand transported by strong winds, mineral material carried by meltwater and organic waste could be the source of the particles. the phenomena of metal complexation and absorption are complicated and depend on many factors, amongst others, on the kind of metal, its concentration, the type of absorbent and its active surface and ph, as well as the kind and concentration of organic and inorganic ligands (vuceta & morgan 1978; upadhyay et al. 2002). our ability to define factors that affect the processes of reducing concentrations of dissolved elements is limited by the absence of detailed data regarding the content and composition of mineral matter and organic matter. however, the recorded reductions of the studied elements may be associated, as has been suggested by sheppard et al. (1997), with the reduced solid particle content in water samples, as fine suspended particles provide the material necessary for adsorption of heavy metals. this has been confirmed by analyses of soil samples collected from lake shores and bottom sediments in antarctica, which showed that the composition of the samples was similar (mentasti et al. 1998). conclusions metal concentrations recorded in the studied surface waters of king george island seem to justify considering them as a reference point with respect to surface waters of other areas of the earth. concentrations of total and dissolved forms of elements were connected with the composition of soils in their surroundings and with atmospheric deposition, mostly took place locally. the increased levels of pb and zn concentrations recorded in the immediate proximity of the research station indicated anthropogenic contamination. significant changeability regarding concentrations of the studied elements indicated that diversely composed rocks were undergoing dynamic and irregular processes of selected elements in surface waters of antarctica a. nędzarek et al. 8 (page number not for citation purpose) citation: polar research 2014, 33, 21417, http://dx.doi.org/10.3402/polar.v33.21417 http://www.polarresearch.net/index.php/polar/article/view/21417 http://dx.doi.org/10.3402/polar.v33.21417 chemical weathering and elements were being leached from the soil by water; it also suggested that mechanisms of their distribution were multidirectional. they depended on chemical mechanisms and chemisorption, as well as complexation and/or chelation of mineral particles and organic matter. a more detailed evaluation of these mechanisms requires further studies focusing on inorganic complexing agents and the composition of organic ligands. references apha (american public health association). 1995. standard methods for examination of water and wastewater. 19th edn. washington, dc: american public health association. birkenmajer k. 2002. retreat of ecology glacier, admiralty bay, king george island (south shetlands, west antarctica, 1956�2001). bulletin of polish academy of science, earth science 50, 15�29. bölter m. 2011. soil development and soil biology on king george island, maritime antarctic. polish polar research 32, 105�116. campbell i.b., claridge g.g.c. & balks m.r. 1994. the effects of human activities on moisture content of soils and underlying permafrost from the mcmurdo sound region, antarctica. antarctic science 6, 307�314. carrasco m.a. & préndez m. 1991. elemental distribution of some soils of continental chile and the antarctica peninsula. projection to atmospheric pollution. water, air and soil pollution 57�58, 713�722. caulkett a.p. & ellis-evans j.c. 1997. chemistry of streams of signy island, maritime antarctic: sources of major ions. antarctic science 9, 3�11. cook a.j., fox a.j., vaughan d.g. & ferrigno j.g. 2005. retreating glacier fronts on the antarctic peninsula over the past half-century. science 308, 541�544. elster j. & komarek o. 2003. ecology of periphyton in a meltwater stream ecosystem in the maritime antarctica. antarctic science 15, 189�201. green j.w., stage b.r., preston a., wagers s., shacat j. & newell s. 2005. geochemical processes in the onyx river, wright valley, antarctica: major ions, nutrients, trace metals. geochimica et cosmochimica acta 69, 839�850. groeneweg w.j. & beunk f.f. 1992. the petrography and geochemistry of the king george island supergroup and admiralty bay group volcanic, south shetland islands. in j. lópez-martı́nez (ed.): geologı́a de la antártida occidental. (the geology of western antarctica.) pp. 46�60. salamanca: congreso geológico de españa iii y viii congreso latinoamericano de geologı́a. howard-williams c., priscu j.c. & vincent w.f. 1989. nitrogen dynamics in two antarctic streams. hydrobiologia 178, 51�61. ikegawa m., kimura m., honda k., makita k., fuju y. & itokawa y. 1997. spring-time peaks of trace-elements in antarctic snow. environmental health perspectives 105, 654�659. juchnowicz-bierbasz m. 1999. year-round changes of nutrients in fresh water bodies near arctowski station (south shetland islands, antarctica). polish polar research 20, 243� 258. juchnowicz-bierbasz m. & rakusa-suszczewski s. 2002. nutrients and cations content in soil solutions from the present and relict penguin colonies (admiralty bay, king george island). polish journal of ecology 50, 79�91. king j.c. 1994. recent climate variability in the vicinity of the antarctic peninsula. international journal of climatology 14, 357�369. kratke j. & wielbińska d. 1981. co-occurrence of particular meteorological elements in the region of arctowski station (king george island, south shetlands) in 1987. polish polar research 2(3�4), 7�21. loureiro a.l.m., vasconcellos m.b.a. & pereira e.b. 1992. trace element determination in aerosols from the antarctic peninsula by neutron activation analysis. journal of radioanalytical and nuclear chemistry 159, 21�28. lu z., cai m., wang j., yang h. & he j. 2011. baseline values for metals in soils on fildes peninsula, king george island, antarctica: the extent of anthropogenic pollution. environmental monitoring and assessment 184, 7013�7021. marsz a.a. & styszyńska a. 2000. główne cechy klimatu rejonu polskiej stacji antarktycznej im. h. arctowskiego (antarktyka zachodnia, szetlandy poludniowe, wyspa króla jerzego). (main climate features of the area of h. arctowski antarctic station [west antarctica, south shetlands].) gdynia, poland: gdynia maritime university. martianov v. & rakusa-suszczewski s. 1990. ten years of climate observations at the arctowski and bellingshausen stations (king george is., south shetlands, antarctica). in a. breymeyer (ed.): global change regional research centres: scientific problems and concept developments. seminar papers and igbp wg 2 report. pp. 80�87. warsaw: polish academy of sciences. mentasti e., abollino o., aceto m. & sarzanini c. 1998. distribution and statistical correlations of major, minor and trace-metals in lake environments of antarctica. international journal of environmental analytical chemistry 71, 245�255. mishra v.k., kim k.-h., hong s. & lee k. 2004. aerosol composition and its sources at the king sejong station, antarctic peninsula. atmospheric environment 38, 4069�4084. nędzarek a. & rakusa-suszczewski s. 2007. nutrients and conductivity in precipitation in the coast of king george island (antarctica) in relation to wind speed and penguin colony distance. polish journal of ecology 55, 705�716. pociecha a. 2008. density dynamics of notholca squamula salina focke (rotifera) in lake wujka, a freshwater antarctic lake. polar biology 31, 275�279. préndez m. & carrasco m.a. 2003. elemental composition of surface waters in the antarctic peninsula and interactions with the environment. environmental geochemistry and health 25, 347�363. a. nędzarek et al. selected elements in surface waters of antarctica citation: polar research 2014, 33, 21417, http://dx.doi.org/10.3402/polar.v33.21417 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21417 http://dx.doi.org/10.3402/polar.v33.21417 santos i.r., silva-filho e.v., schaefer c.e.g.r., albuquerquefilho m.r. & campos l.s. 2005. heavy metal contamination in coastal sediments and soil near the brazilian antarctic station, king george island. marine pollution bulletin 50, 185�194. sheppard d.s., deely j.m. & edgerley w.h.l. 1997. heavy metal content of meltwaters from the ross dependency, antarctica. new zealand journal of marine and freshwater research 31, 313�325. skvarca p., rack w.m., rott h., ibarzabal h. & donangel t. 1998. evidence of recent climate warming on the eastern antarctic peninsula. annals of glaciology 27, 628�632. statsoft inc. 2011. statistica data analysis software system, version 10.1. accessed on the internet at www.statsoft.com on 12 june 2011. styszyńska a. 1990. the effect of wind direction and orography on air temperature at the arctowski station. polish polar research 11, 69�93. suttie e.d. & wolff e.w. 1993. the local deposition of heavy metal emissions from point sources in antarctica. atmospheric environment 27a, 1833�1841. tatur a. 1989. ornithogenic soils of maritime antarctic. polish polar research 10, 481�532. toro m., camacho a., rochera c., rico e., bañón m., fernández-valiente e., marco e., justel a., avendaño m.c., ariosa y., vincent w.f. & quesada a. 2007. limnological characteristics of the freshwater ecosystems of byers peninsula, livingston island, in maritime antarctica. polar biology 30, 635�649. ugolini f.c. & anderson d.m. 1973. ionic migration and weathering in frozen antarctic soils. soil science 115, 461�470. upadhyay s., liss p.s. & jickells t.d. 2002. sorption model of dissolved aluminum in freshwaters. aquatic geochemistry 8, 255�275. vinocur a. & unrein f. 2000. typology of lentic water bodies at potter peninsula (king george island, antarctica) based on physical�chemical characteristics and phytoplankton communities. polar biology 23, 858�870. vuceta j. & morgan j.j. 1978. chemical modeling of trace metals in fresh water: role of complexation and adsorption. environmental science & technology 12, 1302�1309. webster j., webster k., nelson p. & waterhouse e. 2003. the behavior of residual contaminants at a former station site, antarctica. environmental pollution 123, 163�179. wedepohl k.h. 1995. the composition of the continental crust. geochimica et cosmochimica acta 59, 1217�1232. wetzel g.r. 2001. limnology: lake and river ecosystems. 3rd edn. san diego: academic press. selected elements in surface waters of antarctica a. nędzarek et al. 10 (page number not for citation purpose) citation: polar research 2014, 33, 21417, http://dx.doi.org/10.3402/polar.v33.21417 http://www.statsoft.com http://www.polarresearch.net/index.php/polar/article/view/21417 http://dx.doi.org/10.3402/polar.v33.21417 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice are bacteria active in the cold pelagic ecosystem barents sea ? t . frede thingstad and ingrid martinussen of the thingstad, t. f. & martinussen, i. 1991: are bacteria active in the cold pelagic ecosystem of the barents sea? pp. 255-266 in sakshaug, e., hopkins. c. c. e. & 0ritsland. n. a. (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, 12-16 may 1990. polar research l o ( 1 ) . bacterial biomass and activity indicators have been studied at low water temperatures (-1.9 t o +4"c) in the barents sea. strong responses by indicators of bacterial activity. such as hydrolytic enzyme and substrate uptake potentials, were observed in association with the development of phytoplankton blooms. at late successional stages of blooms, observation by cpifluorescence microscopy revealed heavy bacterial colonisation of detrital matter, in particular of senescent colonies of phaeocystis poucherii. based on the retention of bacteria on filters of 1 pm pore size, up to 55% of the bacterial population was estimated to be attached to organic aggregates in some cases. based on thymidine incorporation and a conventional conversion factor, bacterial generation times as short as one day were estimated at temperatures below zero. changes in substrate availability governed by the successional stages of the planktonic ecosystem seem t o be more important as controlling factors for bacterial growth than the low temperatures of the barents sea. t. frede thingsfad and 1. martinussen. deparfment of microbiology and plant physiology, university of bergen, jahnebakken 5. n-5007 bergen. norway. introduction pelagic food webs are dynamic systems where both transient responses and equilibrium states depend upon the interactions between a large number of processes. if these processes differ in temperature sensitivity, the balance between them may shift, and, as a result, food webs in polar regions may theoretically behave differently than those of temperate regions. one such mech anism was proposed by pomeroy & deibel(l986) when considering bacterial degradation of organic material. based on data indicating low bacterial activity below +4"c, they made the suggestion that bacterial processes are of less importance in cold than in temperate waters. one of the significant aspects of such a mechanism is the potential effect of temperature on the relative importance of bacterial dissolution/degradation of particulate matter, versus metazoan feeding on these particles. with the large variation expected in time and space for both of these processes, and with the technical difficulties associated with their measurement, a direct comparison of the relative importance of these two processes for different regions is not easily obtained. if, however, bac terial growth in cold waters is severely inhibited, phytoplankton blooms in cold waters would not be expected to be followed by any strong responses in bacterial biomass or activity. a pre dominance of metazoan consumption prior to bacterial invasion of detrital particles would also make the observation of colonised particulate material unlikely. in the polar and meltwater regions of the bar ents sea, phytoplankton blooms occur at water temperatures close to freezing point (skjoldal & rey 1989), and the subsequent processes of dom and detrital pom transformation must also occur at this low temperature. these blooms are often dominated by the colony forming prymnesio phyte phaeocystis pouchetii (skjoldal & rey 1989). in temperate areas, phaeocystis blooms have been shown to leave large amounts of organic material in the water (eberlein et al. 1985), and after a delay of 5-10 days, the blooms are followed by a development of planktonic bac teria (billen & fontigny 1987). if low-tem perature inhibition of bacterial degradation is important, one would expect bacterial responses to phaeocystis blooms in the barents sea to be feeble, more delayed or even absent. processes related to the bacterial dissolution and degra dation of particles involves the hydrolysis of macromolecules, the uptake of monomers, and the formation of bacterial biomass. we have found that bacterial abundance, activity poten 256 tials for hydrolytic enzymes and uptake potentials for monomers, as well as the incorporation rate of thymidine. all increase i n response to phy toplankton blooms occurring at temperatures between -1 and +4oc i n the barents sea. i n senescent blooms. massive bacterial invasion of colonies was also observed. little support was therefore found for a bacterial response quali tatively different from that described in temperate waters. t . f. thingstad & i . martinussen materials and methods sampling samples were collected by a rosette sampler with niskin water bottles attached to the ctd sonde, or, when large volumes were required, by 30l niskin bottles shortly after the ctd cast. geo graphical position of stations are given in fig. 1. the stations are from different cruises: stations 14. 24. 31. 52 are from cruises with coast guard vessels k / v andenes and k ~ v s e n j a in april 1986. 80 z 0 78 76 w 0 2 74 l j a stations 733. 890 and 961, with r/v g . 0. sars in june 1984. august 1985 and june 1987, respect ively. temperature dependence of proteases was measured on a sample of brown ice collected in april 1986 and thawed at an ambient temperature of 10°c. incubations where performed at close to in situ temperature in a thermostatted water cooled incubator, or, for temperature depen dence studies, in a temperature gradient incu bator described by eriksen & g o k s ~ y r (1976). microscopic counts heterotrophic and autotrophic picoand nano plankton were counted by epifluorescence micro scopy according to martinussen & thingstad (1991). due t o a double staining with primuline and dapi and t h e alternation between blue and uv-exitation in the epi-fluorescence microscope, this procedure allows identification of autotrophs by chlorophyll autofluorescence, positive identi fication of cells based on the existence of a dapi stained nucleus. and the visualisation of the whole j 890 24, ,961 v i e 14 31 0 bjerneya i 7 2 i norway 70 i i i i 0 20 30 40 i l o n g i t u d e o e fig. i . positions of stations in the barcnts sea. 3 are bacteria active in cold waters? 257 cell by the primuline stain. the primuline stain also allowed the visualisation of the mucus of phaeocystis colonies. samples were fixed with 2.5% final concentration of borate-buffered for malin. as a standard procedure, a 5 m l sample was filtered on a 0.2 pm pore-sized polycarbonate filter for bacterial counts and between 15 and 50 ml, dependent upon expected population den sity, on a 1 pm filter for counting of eucaryotes and retained bacteria. bacterial cell volumes were calculated from linear dimensions determined in the microscope at looox magnification using a calibrated graticule (new porton g12, graticules ltd., england) in one ocular. enzymatic activity potentials activity potentials for protease and fglucosidase were determined according to somville & billen (1983) and somville (1984) using a perkin-elmer ls5 fluorescence spectrophotometer. thymidine incorporation thymidine incorporation into cold tca-pre cipitable material was determined according to fuhrman & azam (1982) modified by increasing the concentration of added thymidine to 10 nmole i-'. conversions from thymidine incor porated to estimates of cell production rates are based on a conversion factor of 2.4 10ir cells mol-' as suggested by fuhrman & azam (1982) for offshore waters. generation times are computed as in2 x cell density (cell production rate)-'. uptake potentials of i4c-labelled glucose and amino a c i h uptake potentials for monomers were measured by adding 37 kbq of 14c-labelled glucose (amer sham cfb.96) or a i4c-labelled amino acid mix ture (amersham cfb.104) to 10ml samples of seawater. final concentrations of glucose and amino acids were 0.37 and 0.38 pmol i ' , respect ively. the different amino acids in the mixture had different specific activities, and conversion from dpm to nmoles are based on mean specific activity of the mixture (68 e q mmol-i). after 5 h incubation, the samples were filtered on 0.2 pm cellulose-nitrate membrane filters. the filters were washed twice with filtered seawater. dried, and counted by scintillation counting. chlorophyll, noj, in-situ fluorescence and light these data were obtained from the sampling pro gramme of the marine research institute, bergen. chlorophyll a concentrations were measured fluorometrically after acetone extrac tion of filtered samples, nitrate was measured by autoanalyser as described in foyn et al. (1981), fluorescence profiles were obtained using a sub mersible fluorometer (q-fluorometer). an excep tion to this is station 961, where profiles of in situ fluorescence, light, and a, profiles are obtained from b. g . mitchell, scripps institution of ocean ography, and were collected using a bio-optical rig (biospherical instruments) equipped with sensors mer-12, mer-08, and mer-53. results ice-edge bloom, april i986 the bacterial development during the first phase of the ice-edge bloom was followed on a cruise fig. 2. station 31. april 1986. profilcs of salinity (broken line). tcmpcrature (solid linc). and protcasc activity potential (solid circles). development of bacterial activitics occurring in thc cold meltwatcr layer on top of warmer atlantic water masses. 258 t. f. thingstad & i . martinussen ~ a i i 1 i i b 6 11 16 21 e 11 16 2 1 1 4 24 31 date april 1986 l 4 24 31 52 52 w t i o n n r . fig. 3. scqucncc of stations during icc-cdgc bloom. samplcs from 10 m dcpth a . chlorophyll (i (opcn triangles). no, (open squares). and tcmpcraturc (opcn circlcs) b. bacterial abundancc (solid circlcs). bactcrial biovolumc (solid squarcs). and generation times estimated from thymidinc incorporation (solid triangles). c. protcase activity potential (solid circles). uptake potential f o r amino acids (opcn circles). d. /?-glucosidasc aetlvity potcntial (solid trianglcs). and glucose uptakc potcntial (open trianglcb). are bacteria active in cold waters? 259 with coast guard vessel k/v andenes in april 1986 in the area west of sentralbanken in the barents sea (fig. 1 ) . the meltwater layer in the area extended down to about 50m (fig. 2). return of the ship to the same area with intervals of a few days allowed the ordering of samples in a time sequence spanning 13 days, permitting an indication of how the bloom in the area devel oped, although bo strict time sequence of the development in a well-defined water body was possible. during the period of observation, the increase in chlorophyll levelled off, and nitrate was consumed. a slight heating of the meltwater layer occurred, with water temperatures at 10 m reaching -1.o"c at the end of the period (fig. 3a). bacterial abundance increased by a factor of 3 in numbers and 5.6 in total biovolume (fig. 3b), the main increase in bacterial bio volume occurred at the end of the period. all measurements of bacterial activity indicated a transition to a phase of active bacterial growth at the end of the period. the enzymatic activity potentials increased throughout the period with factors of 60 and 40 for 6-glucosidase and protease respectively. due t o a temporary failure of the scintillation counter, uptake measurements are only available for stations 31 and 52, but glucose and amino acid uptake potentials both showed the same rapid increase as the enzyme activity potentials (fig. 3c, d). the bacterial response was restricted to the cold water layer with no response in the warmer atlantic water below as illustrated by the profile of protease activity potential in fig. 2. estimates of bacterial gen eration times from thymidine incorporation indi cated a decrease in mean generation time of the bacterial population from 13 to 4 days between the 8th and the 13th day of the period (fig. 3b). subsurface chlorophyll maximum station 961, in the central barents sea, june 1987, is an example of a later successional stage where a sharp subsurface chlorophyll a maximum has developed at the pycnocline (fig. 4a) between the meltwater layer and the underlying atlantic water. the autotrophic community was com pletely dominated by phaeocystis. the profile of bacterial abundance had a sharp peak very similar to the distribution of phaeocystis cells (fig. 4b), but with a maximum of 2 . lo6 ml-' shifted slightly downwards in the water column relative to the peak in abundance of phaeocystis. activity poten tials of hydrolytic enzymes and uptake of glucose and amino acids all indicated the same type of depth profiles with peaks associated with the upper part of peak in bacterial abundance (fig. 4c, d). at this station, colonies of phaeocystis were still relatively free of bacteria, and maximum retention of bacteria on 1 pm filters was 10% at 10m. at the fluorescence maximum 3% were retained. bloom in water without well-defined pyknocline station 733 in the eastern barents sea, june 1984, represents a situation with temperatures below zero at all depths. there was no distinct pycno cline, but a gradual increase in ut downwards. (fig. 5a). the in situ fluorescence increased down to 20 m which corresponded to the bottom of the photic zone. a broad maximum in the fluor escence profile extended down to about 60 m with a long "tail" extending to the lowest measured depth at 90 m. chlorophyll at the depths of maxi mum fluorescence corresponded to 3.8 pg chl i ' . estimates of bacterial generation time had two minima, 1.2 and 1.5 days, at the surface and at 30m respectively (fig. 5b). heavily invaded phaeocystis colonies were observed and bacterial retention on 1 pm reached a maximum of 40% at 30m depth (fig. 5b). post-bloom situation. august 1985 station 890 in the central barents sea, august 1985, represents a situation with low values of in situ fluorescence throughout the water column, combined with nutrient depletion above the pycnocline (fig. 6a). except for a maximum of 0.9 pg chl * i ' at 20 m, values were below 0.4 pg chl i ] . water temperature above the pycno cline at 10m were +4"c, decreasing to -1.8 in the underlying polar waters. the phytoplankton community was dominated by a small, unidenti fied picoplanktonic species approximately 1.5 pm in diameter and by dinobryon spp. the fastest bacterial growth was found at the bottom of the pycnocline (20m) (fig. 6b) where a bacterial generation time of 1.0d was estimated. at all depths of this station, aggregates with bacterial colonisation were observed, a feature particularly prominent at 20m. this was reflected in a high fraction (55%) of the bacterial population being retained on 1 pm polycarbonate filters. the extreme maximum of bacterial retention in the 260 t. f. thingstad & i . martinussen t e m p e r a t u r e " c 1 . 0 0 5 0 0.5 1 0 phaeocvstis cells 0 1 2 i u m i n situ :iuorescence re1 units 0 1 2 3 4 1 b a c t er i q 0 2 106in1-1 2 7 6 21 20 0 gt amino acid upt.n h e 0 g l u c o s e u p t a k e a nm0l.l" .h' 0 0 1 0 2 o 3 nrnol.l".h' o 002 0 0 4 006 0 o r i i i p r o t e a s e a c t i v i t y p o t e n t i a l nmol q' 41.' > i c 0 glucosidase act. p o t e n t i a l a 0 0 . 5 1 . o 1 . 5 nrnot .i-' .ti1 d are bacteria active in cold waters? 261 fluoresc. rehnits nitrate amol-l-' 0 2 k 6 8 1 0 i"" ~ , 1 1 1 2 6 21.6 21.8 1 0 temp o(: oi 0 25 e i w 0 50 15 100 bad. abundance 1o'mi-l . gemtime d 8 i i i 20 40 60 % retained fig. 5. bloom in water without well-defined pycnocline. station 733, june 1984. a . profiles of fluorescence (solid line). tem perature (dotted line). u, (broken line) and nitrate (open squares). b . bacterial abundance (solid triangles). generation time estimates (solid squares), and percentage of bacterial population retained on 1 pm polycarbonate filters (solid circles). vicinity of the pycnocline was specific for this station. the origin of the organic aggregates at this station is unknown. at other stations, however, senescent colonies of phaeocystis p o u chetii heavily colonised by bacteria were easily recognisable. classification of the water samples according to whether the phytoplankton com munity was dominated by phaeocystis, the unidentified picoplankton sp., a mixture of these, or dominated by other species demonstrated a clear correlation between the phaeocystis/ picoplankton communities, and a high retention of bacteria by 1 pm filters (fig.7). temperature sensitivity of protease the arrhenius plot for hydrolysis of the artificial substrate by the natural mixture of proteases in brown sea ice was linear (r2 = 0.996) in the inter val 1.5 (lowest temperature investigated) to 21°c (fig. 8). the slope of the linear part cor responds to an activation energy of 12.1 kcal . mole-' which corresponds to a qlo in the range -1.5 to 8.5"c of about 2.2. discussion bacterial abundances and activities, not drast ically different from those of temperate waters, may develop in the barents sea, even at subzero temperatures. this is a conclusion in accordance with results previously reported by investigators in the antarctic ocean (hodson et al. 1981; han son & lowery 1985). we found, however, a large range in values of thymidine uptake, from less than 0.004 nmole . i ' . day-' in samples taken in late winter before the onset of the ice edge bloom to 0.26 nmole i-' . day-' in connection with deep chlorophyll maxima in august. our sampling did not allow a strict deter mination of the timing between the peak of the ice-edge phytoplankton bloom and the bacterial response. the sequence of stations in april 1986 (fig. 3) did, however, suggest that the response was initiated even before the exhaustion of the nitrate. no indications were found of a delay substantially longer than the 5-10 days reported for temperate waters by billen & fontigny (1987). at later stages of the bloom, a close correlation between the profile of bacterial abundance and the deep fluorescence maximum could be observed (fig. 4), with bacterial abundances up fig. 4. deep fluorescence maximum, station 961. june 1987. a . fluorescence (solid line), temperature (dotted line) and u, (broken line). b . cell counts of phoeocysfis (solid triangles), and bacteria (solid squares). c. protease activity (solid squares) and amino acid uptake (open squares) potentials. d . b-glucosidase activity (solid triangles), and glucose uptake (open triangles) potentials. 262 t. f. thingstad & i . martinussen f i u o r escen ce .. r e i. un i t s iri 5 10 0 b a, 26.5 2 2 0 27.5 28.0 j i i i n i t r a t e pm 0 5 10 1 5 10 20 30 e i= : lo 5 0 60 7 5 0 5 t e m p , o c i i 1 1 0 20 40 60 ‘10 r e t a i n e d 0 1 50 40. 30 20 10 ( 4 33 11 5 0 ph pi ph+pi phytoplcommuni t y fig. 7. retention of bacteria on 1 pm polycarbonate filters. water samples from cruise in august 1985 classified according to dominance of phytoplankton community by phaeocysrk (ph). picoplankton (pi). a combination of these (ph + pi). or by other groups (0). bars and vertical lines indicate mean and range. rcspectivclv. number of water samples in each category givcn abobc each bar. f q 6 post-bloom situation. station xyo. august iy8.5 a profiles of fluorescence (solid line), temperature (dotted line). u, (hroken line), and nitrate (open squares). b. bacterial ahun dancc (solid triangles). generation time cbtimatcs (solid squarca), and retention on i u m polycarbonatc filters (solid circles). are bacteria active in cold waters? 263 3.5 3.0 2.0 2 ’ o fig. 8. arrhenius plot of the rate of hydrolysis of l-leucyl-pnaphtyl amide by proteases from a sample of brown ice . \ 8 \ temp i oc 30 i 21 i i 1 3 i 5 ‘i \. to 2 + lo6 ml-l, similar to levels observed in coastal temperate waters (azam et al. 1983). our gen eration time estimates are based on a conversion factor between thymidine incorporation and cell production rate which is not determined for the actual environment(s). since the factor is known to vary (fuhrman & azam 1982; riemann et al. 1987), our generation time estimates must be taken as indicative only. some of the higher values obtained for the conversion factor seem, however, t o be associated with the addition of thymidine at concentrations below 10 nmole * i-’, while lower values have been determined in coastal waters (riemann & bell 1990). the fastest growth with generation times about 1 day are, however, comparable to generation times esti mated in temperate waters. as an example, rie mann et al. (1984) report values based on thymidine uptake between 17 and 91 hours through a die1 cycle in a danish coastal environ ment. in laboratory studies, harder & veldkamp (1971) reported a maximum growth rate of 0.073 h-l at -2°c for one of the species inves tigated (pseudomonas l12), corresponding to a generation time of 9.5 hours. this is below the generation times estimated by us, and dem onstrates the feasibility at low temperatures of generation times that are short when viewed in an ecological context. the maximum protease activity potential observed at station 52 (fig. 3c) was 1 . 1 nmole * i-’ . min-l. using the tempera ture dependence determined, this corresponds to an activity of about 3 nmole i ] . min-l around 15°c. this is comparable to typical values reported by fontigny et al. (1987) for coastal seawater in the north sea, although maximum values found in this more eutrophic environment exceeded 20 nmole . i-’ . min-l. from the visual observation of how bacterial microcolonies had formed on senescent phaeo cystis colonies, we felt fairly convinced that the colonisation was accompanied by active growth of attached bacteria. we have, however, no esti mate of the relative proportion between those bacteria that were primary invaders and their offspring on the mucous material. in situations with high mucus content of the water, the reten tion of bacteria by 1 pm filters may overestimate the proportion of attached bacteria due to entrap ment of bacteria in the mucus during the filtration process. the observation of colonies without attached bacteria during early stages of the blooms do, however, show that fresh mucus did not collect bacteria during the filtration process. while we feel confident that our observation shows that detrital particulate matter is colonised, we can not determine to what degree the material had been respired. a possible difference in the temperature responses of growth and respiration has been suggested (christian & wiebe 1974). a large temperature dependence for respiration could imply a large change in consumption rate 264 of organic matter, without this being revealed in measurements related to changes in bacterial biomass. temperature has been shown to influence most of the important growth parameters for bacteria. in a study of aerobacter aerogenes (25 to 40°c). topiwala (1971) found that parameters such as the half saturation constant for growth and endogenous metabolism were temperature dependent. harder & veldkamp (1967) found that a decrease in temperature was compensated for by an increase in the concentration of rna and respiratory enzymes. bacterial degradation of organic matter within an ecosystem context is, however, not simply a function of the physio logical properties of the bacteria; degradation may also be strongly controlled by trophic inter actions such as competition, predation, and remineralisation (pengerud et al. 1987), and therefore by the temperature dependence of such processes. in a system where bacterial growth rate is controlled by organic or inorganic substrate limitation. moderate changes in maximum growth rate with temperature may be unimportant or compensated for by the dynamics of the system. an example is perhaps a possible compensation for low temperature by high substrate con centrations as suggested by pomeroy & wiebe (1988). supporting evidence for this was found in investigations of amino acid concentrations and bacterial activity in the arctic (pomeroy et al. 1990). if extracellular hydrolysis is the rate limiting step of macromolecular degradation as suggested by billen (1988), the temperature dependence of this process is particularly important. the exten sion of the linear part of the arrhenius plot for hydrolysis by barents sea proteases t o tem peratures below 0°c (fig. 8) demonstrates that enzymes functioning normally at low tempera tures have developed in this ecosystem. the exist ence of bacteria with a complete enzymatic machinery functioning normally at low tem peratures has been demonstrated two decades ago by harder 81 veldkamp (1971) who studied a group of pseudomonas spp. for which the linear part of the arrhenius plot for maximum growth rate extended down t o between 4 and -5°c. qlo values reported for enzyme catalysed reactions in natural systems seem to be fairly uniform. the value of about 2.2, corresponding t o an activation energy of 12.1 kcal . mole-', found for hydrolysis by barents sea proteases, can be compared to the t . f. thingstad & i . martinussen value 12.0 kcal . mole-' reported for hydrolysis of casein with trypsin (white et al. 1968), to the value of 11 kcal . mole-' reported for maximum growth rate of both obligate and facultative psych rophilic bacteria (harder & veldkamp (1971), or to a range of q l o values between 1.8 and 2.3 for photosynthetic capacity of natural phytoplankton as reviewed by harris (1980). any extreme sensitivity of bacterial processes to low temperatures of the type suggested by pomeroy & deibel (1986) or pomeroy & wiebe (1988) does therefore not seem to be of universal validity or to be a necessary consequence of any fundamental limitations in bacterial physiology. the reason for this apparent discrepancy in results is not immediately obvious. one may speculate on the possibility that there are differences in the composition of the bacterial community in permanently and in seasonally cold waters. polar water masses i n the barents sea are characterised by temperatures below 0°c. the atlantic inflow has a mean of 6.2"c, but this decreases rapidly east and northwards into the barents sea (loeng 1989), and the barents sea therefore classifies as a permanently cold environment. in a one-year study in the baltic when surface temperatures varied from 0 to 14t, kuosa & kivi (1989) found a peak in bacterial production following the spring phytoplankton bloom in a period during which water temperatures increased from 2 to 6°c. this was a result seemingly in qualitative accordance with our results from the barents sea. in experi ments with water collected in april from thz same area, however, bacterial growth was not found when filtered samples were incubated at in situ temperature (+ 1"c), although higher incubation temperatures induced rapid bacterial growth (autio 1990), suggesting that cold-adapted bac teria were not present. a unified picture of how the bacterial community adapt to temperature in permanently and in seasonally cold environments seems therefore still to be lacking. ecosystem behavior is a result not only of the interactions between biological processes but also of the interactions between biological and physi cal processes. perhaps the latter is a field where differences in temperature dependence of inter acting rates is more likely t o be expected. as an example, viscosity of 35% seawater decreases by a factor of only 1.36 between 0 and 10°c (knauss 1978). one may speculate whether this response is sufficiently small to shift the balance between sedimentation and degradation rate of particles are bacteria active in cold waters? 265 and, as a result, influence the degree of nutrient impoverishment of the meltwater layer or the amount of organic material reaching the sedi ments. such a shift would constitute a third element to be considered in the discussion of whether a match in time between the spring phy toplankton bloom and the development of mezo zooplankton is important for the partitioning of the primary production between sedimentation and predation by metazoans in the barents sea ecosystem (rey et al. 1987; wassmann 1989). it would also effect the carbon budget of the upper ocean. acknowledgements. this work is part of the norwegian research program for marine arctic ecology (pro mare) and was financed by the norwegian research council for science and the humanities and the norwegian ministry of the environ ment. we wish to thank colleagues within this programme for cooperation on the cruises and for supplying ctd, fluorescence and mineral nutrient analyses used in this article and 1. dundas for comments on the manuscript. references autio, r. m. 1990: bacterioplankton in filtered brackish water cultures: some physical and chemical parameters affecting community properties. arch. hydrobiol. 117. 437451, azam. f.. fenchel, t., field, j . g . , gray, j . s., meyer-reil. l. a . & thingstad, t. f. 1983: the ecological role of water column microbes in the sea. mar. ecol. prog. ser. 10. 257 263. billen, g . 1988: delayed development of bacterioplankton with respect to phytoplankton: a clue to understanding their trophic relationships. 4th inr. workshop on measurement of microbial activities in the carbon cycle. ceske budejovice, czechoslovakia. billen, g. & fontigny, a. 1987: dynamics of phaeocystis dom inated spring bloom in belgian coastal waters. 11. bac terioplankton dynamics. mar. ecol. prog. ser. 37, 249-257. christian, r . r., & wiebe. w. i . 1974: the effects of tem perature upon the reproduction and respiration of a marine obligate psychrophile. can. 1. microbiol. 20, 1341-1345. eberlein, k . , leal, m. t.. hammer. k. d. & hickel. w. 1985: dissolved organic substances during a phaeocystis pouchefii bloom in the german bight (north sea): mar. biol. 89,311 316. eriksen. j . & gokseyr. j . 1976: the effect of temperature on growth and cellulase (p-1 .4-endoglucanase) production by the compost fungus chaetomium fhermophile var. dissitum. arch. microbiol. 110. 233-238. feyn, l . . hagebe, m. & seglem. k. 1981: automatisk analyse av nmingssalter med "on-line" databehandling. fisken og h a w . serie b . fontigny, a.. billen. g . & vives rego, j . 1987: some kinetic characteristics of exoproteolytic activity in coastal seawater. est. coast. mar. sci. 25, 127-134. fuhrman, j. a . & azam, f. 1982: thymidine incorporation as a measure of heterotrophic bacterioplankton production in marine surface waters: evaluation and field results. mar. biol. 66, 1 w 1 2 0 . hanson, r. b. & lowery, h . k. 1985: spatial distribution, structure, biomass. and physiology of microbial assemblages across the southern ocean frontal zones during the late austral winter. appl. enuiron. microbiol. 49. 1029-1039. harder, w. & veldkamp. h. 1967: a continuous culture study of an obligately psychrophilic pseudomonas species. arch. microbiol. 59, 123-130. harder, w. & veldkamp, h. 1971: competition of marine psychrophilic bacteria at l o w temperatures. antonie iian leeuwenhoek 37, 51-63. harris, g . p. 1980: the measurement of photosynthesis in natural populations of phytoplankton. pp. 129-187 in morris. 1. (ed.): the physiological ecology of phyroplankton. blackwell. oxford. hodson, r. e., azam. f., carlucci. a. f., fuhrman, j . , karl. d . m. & holm-hansen. 0. 1981: microbial uptake of dis solved organic matter in mcmurdo sound, antarctica. mar. biol. 6 1 , 89-94. knauss, j. a . 19 7 8: introduction 10 physical oceanography. prentice hall p. 324. kuosa, h. & kivi, k. 1989: bacteria and heterotrophic flag ellates in the pelagic carbon cycle of the northern baltic sea. mar. ecol. prog. ser. 53, 95-100. loeng, h. 1989: ecological features of the barents sea. in: rey, l. & alexander, v. (eds.): proc. 6th conf. com. arctique internat., 13-15 may 1985. e . j . brill. leiden 1989. martinussen, i . & thingstad. t. f. 1991: a simple double staining method for enumeration of autotrophic and het erotrophic nanoand picoplankton. mar. mirrob. food webs 5 , 5 1 1 . pengerud, b.. skjoldal, e. f. & thingstad. t . f. 1987: the reciprocal interaction between degradation of glucose and ecosystem structure. studies in mixed chemostat cultures of marine bacteria. algae. and bacterivorous nanotlagellates. mar. ecol. prog. ser. 35. 111-117. pomeroy, l. r. & deibel. d. 1986: temperature regulation of bacterial activity during the spring bloom in newfoundland coastal waters. science 233, 359-361. pomeroy, l. r.. macko, s . a , , ostrom, p. h. & dunphy. j . 1990: the microbial food web in arctic seawater: con centration of dissolved free amino acids and bacterial abun dance and activity in the arctic ocean and in resolute passage. mar. ecol. prog. ser. 61, 31-40. pomeroy. l. r. & wiebe, w. j . 1988: energetics of microbial food webs. hydrobiologia 159, 7-18. rey, f.. skjoldal. h. r. & slagstad. d . 1987: primary pro duction in the barents sea. pp. 29-46 in loeng. 13. (ed.): the effect of oceanographic conditions on distribution and population dynamics of commercialfish stocks in the barents sea. proc. 3rd sovict-norwegian symp. murmansk. 2 6 2 8 may 1986. riemann, b. & bell, r . t.. 1990: advances in estimating bacterial biomass and growth in aquatic systems. arch. hydrobiol. 4 . 385-402. riemann. b., bjdrnsen. p. k . . newell. s. y . & fallon. r. d. 1987: calculation of bactereplankton production from measurements of 'h-thymidine incorporation. limnol. oce anogr. 32, 471-476. riemann, b.. niclsen. p., jeppesen. m.. marcussen, b. & fuhrman. j . a . 1984: die1 changes in hacterial biomass and growth rates in coastal environments. determined by means of thymidine incorporation into dna, frequency of dividing 266 t. f. thingstad & 1. martinussen cells(fdc). and microautoradiography. m a r . ecol. f r o g . ser. 17, 227-235. skjoldal. h. r & rey. f. 1989: pelagic production and varia bility in the barents sea ecosystem. pp. 242-286 in sherman. k . & alexander. l (eds.): biomass yields ondgeography of large marine ecosysrem. aaas selected symposium 1 1 1 . westview press, boulder. colorado. usa. somville. m. 1984: measurement and study of substrate speci ficity of exoglucosidase activity in eutrophic water. appl. enoiron. microbiol. 48, 1181-1185. somville. m. & billen. g . 1983: a method for determining exoproteolytic activity in natural waters. limnol. oceunogr. 28. 1%193. topiwala. h . 1971: temperature relationships in continuous culture. biofechnol. bioeng. 13. 795-813. wassmann. p. 1989: sedimentation of organic matter and sili cate from the euphotic zone of the barents sea. rapp. p:u. r e u n . corn. lnr. explor. mer 188. lo&l14. white a . handler. p. & smith, e. l. (eds.) 1968: principles of biochemrtfrv. mcgraw-hill. new york. 233 pp. photosynthesis-irradiance relationships in natural phytoplankton populations of the barents sea francisco rey rey. f . 1991: photosynthcsis-irradiance relationships in natural phytoplankton populations of the barents sea. pp.105-116 in sakshaug, e . . hopkins. c. c . e. & britsland. n . a . (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim. 12-16 may 1990. p o / a r research i o ( 1 ) . an analysis is made of the photosynthesis-irradiance relationships in natural phytoplankton populations in the barents sea. the data set comprises 232 experiments carried out during a 10-year period, both in open and ice-covered waters. the variability on the p-1 parameters is discussed and examined in relation to the variation in a variety of environmental conditions. the results suggest that in the barents sea. as in other arctic areas, phytoplankton photosynthesis is mainly controlled by physical variables. however, control of the phytoplankton stock. i . e . by zooplankton grazing, seems also to have a considerable indirect influence on p-i parameters, especially after the spring bloom and the depletion of winter nutrients. “ ‘ ‘ . ~ l a r \ n s ~ ’ ’ francisco r e y . institute of marine research. p . 0. box 1870 nordnes. n-5024 bergen. n o r w a y (revised m a y 1 9 9 1 ) . introduction as in other polar seas, phytoplankton in the bar ents sea are exposed to extreme seasonal vari ations of such environmental conditions as day length, available light, water column stability, and water temperature. especially important is the fact that the barents sea is dominated by two different water masses: cold arctic waters flowing in from the north and warmer atlantic waters flowing in from the south, giving rise to a marked front. in addition, the northern halfof the barents sea is seasonally covered by ice. since 1979, the institute of marine research has carried out biological oceanographic inves tigations in the barents sea. studies have been focused mainly on the feeding conditions of the capelin stock in order to elucidate the large annual and geographical variations i n the growth of this fish species (skjoldal & rey 1989). these inves tigations were incorporated into the norwegian research program for marine arctic ecology (pro mare) in 1984 and were concluded in 1989. during this period, a series of phytoplankton photosynthesis-irradiance experiments were car ried out. the aim of these experiments was to characterise the primary production potential of the barents sea. the data set obtained from these experiments is presented here and analysed with respect to the relationships between the par ameters of the photosynthesis-irradiance curve and other environmental parameters. for logis tical reasons the bulk of the data was collected during the boreal spring and summer. material and methods the data employed in this analysis of phyto plankton photosynthesis were derived from 232 photosynthesis-irradiance experiments carried out between 1980 and 1989. samples represent different seasons, types of water masses, ice cover, and depths. the samples were usually taken from the upper mixed layer, the subsurface chlorophyll maximum (if present), and from below the pycnocline. fig. 1 shows the location of the sampled stations while table 1 presents an overview of the collected data. two types of incubators were used for meas uring the uptake of radioactive carbon. the first, called the low-light incubator (ll), was equipped with daylight-type fluorescent tubes (osram 191 daylight 5000 de luxe) that, combined with neu tral density plexiglass filters, gave ten different quantum scalar irradiances in the range from 0 to 390 pmol m-2 s-i. the sample volume was 100 ml of seawater, to which 148 kbq (4 pci) of radio active carbon were added (the international agency for i4c determination, denmark). the incubation time was about 4 hours. the second incubator, a high-light type (hl), was equipped with an halogen-metal lamp (osram power 106 franckco rev 80 -. 78 16 74 a f y 0 72 i i t 10 20 30 40 50 imgitude ( 'e) fig i station locations in the barents sea star, 400 w ) that, combined with neutral density filters, gave 11 different intensities in the range from 0 t o 1700 pmol m ' s ' of quantum scalar irradiance. to a sample volume of about 300 mi. about 1480 kbq (40 pci) was added. after gentle a thermostat-controlled water bath. in all cases, incubation was terminated by immediate filtration through millipore membrane filters of 0.45 pm pore size. thereafter, the filters were either kept frozen at -18°c for further treatment ashore or analysed on board. t h e filters were fumed for 15 minutes with concentrated hydrochloric acid, after which 7 ml of instagel ( u p t o 1986) or opti fluor was added. t h e radioactivity o n t h e filters was measured with a packard tri carb scin tillation spectrometer using t h e channel-ratio method for estimating counting efficiency. t h e photosynthesis-irradiance curve parameters were estimated using the model described by platt e t al. (1980): p b = p:(i e-ab'/p:)e-flb'/pfl pb: photosynthetic rate [mgc (mgch1)-' h-'1 p! : light-saturated photosynthetic rate in the absence of photoinhibition [mgc (mgchl)-' h-'1 ab: initial slope of t h e p-i curve [mgc (mgchl)-' h-' (pmol m-' s ' ) ' ] . i : quantum scalar irradiance ( p m o l m-2 s-i) bb: index of photoinhibition (mgc (mgch1)-' h-' (pmol m-? s ' ) ' ] mixing, 20ml aliquots were poured into pyrex bottles with a n automatic dispenser and incubated for about 2 hours. when working in open sea areas, the temperature in t h e incubators was kept after fitting t h e equation t o t h e data (nelder & mead 1965), the following derived parameters were calculated (platt e t al. 1980): at in situ temperature by a continuous flow o f p k = p?[cub/(ab + b b ) ] * [/3"/($ + pb)]@b'"b, subsurface seawater (about 4 m depth). in icethe maximum observed photosynthetic covered waters and in front areas, the tem perature in the incubators was maintained at i, = p:/(~", an index of photoadaptation 51°c of the in situ temperature by means of rate [mgc (mgchl)-' h-'] (pmol m-' s-') t o b k 1. overview of the data sets utilised number of year observation$ month sampling incubator main type of depth, ( m ) 'ypc watermasses 1980 1981 1982 1983 1989 3 '9 8 49 37 zh 27 39 12 july may. july. august may. june may. june junc. august august april february. may. june may -5-35 0-45 (l30 6 8 0 ll l l l l ll ll ll ll h l h l open waters open waters open waters ice-covcrcd waters open waters open waters open waters ice-covered waters ice-covered waters open waters open water5 ll = low-light incubator h l = high-light incubator photosynthesis-irradiance relationships in the barents sea 107 i, = pf/ab in[(# + pb)/pb], the irradiance at which photosynthesis is at maximum (ymol m-* s-l) ib = p:/flb, an index for photoinhibition sus ceptibility (ymol m-2 s-') chlorophyll a concentrations were determined by filtering known volumes of seawater through membrane filters of 0.45 ym pore size. the filters were kept frozen for a few days and then dissolved in 90% acetone. the pigments were extracted overnight at 4'c, centrifuged, and then their fluorescence was measured before and after acidi fication in a turner designs fluorometer. the fluorometer was calibrated against commercially purified chlorophyll a (sigma chemical co.). nutrients were measured onboard immediately after collection with standard methods adapted to an autoanalyser (foyn et al. 1981). results and discussion environmental parameters the average seasonal distribution of par (photosynthetically active radiation) at bj0rncbya (74'15") which lies at the mean latitude of the barents sea is shown in fig. 2. during the arctic winter, incident light is hardly detectable. the first recordable light appears in mid-february and increases exponentially thereafter and reaches a maximum total daily irradiance in mid-june. the greatest temporal increase in incoming irradiance is usually observed in april. the average hourly irradiance, however, increases exponentially somewhat earlier than the total daily irradiance and levels off at the end of april. hydrographic conditions were extremely vari able, ranging from relatively warm atlantic waters of high salinity to cold arctic water masses, in many cases near the freezing point. fig. 3 shows the temperature-salinity relationships at the depths from where the water samples were col lected. about 60% of the samples were collected either from atlantic or arctic water proper and about 25% from meltwater. the remainder was collected in areas with different degrees of mixing between the main water masses. variations in p-i parameters the frequency distributions of the parameters of the p-i curve for the whole investigated period are shown in fig. 4a-e. for most of the par ameters, a positive skewness of the values was evident, as has been found in previous polar inves tigations (harrison & platt 1986). pft, ranged from 0.27 to 7.3 mgc (mgchl)-' h-' with a mean of 1.73; a" ranged from 0.0037 to 0.1633 with a mean of 0.0440 mgc (mgch1)-' h-' 0 60 120 180 240 300 360 julian day fig. 2. average (ly7g-ly89) seasonal distribution of photosynthetically active radiation (par) at bjarnaya. a . total daily irradiance. b . average hourly irradiance (lit hours). 108 francisco rey h 32.0 33.0 34.0 35.0 salinity fig. 3 temperature-salinity relationships at the sampling depths. a . atlantic water: b . arctic water: c i . spring mclt water: c2 summer melt water: d mixed atlantic and mclt waters in surnmer/autumn: e . mixed atlantic and arctic w a l c r s (pmol m-? s ' ) i ; bb ranged from 0 to 1.085 mgc (mgchl)-' h-' (pmol m-? s ' ) ' with a mean of 0.0312; i, ranged from 19 to 891 pmol m-'s-i with a mean of 190; il ranged from 4 t o 3 1 9 p ~ 1 o l r n ~ s ~ with a mean of 47; i h ranged from 49 to infinite. for pb and i h , the number of observations was reduced to 194 by excluding a series of experiments for which the light intensity of one of the incubators (ll) was not sufficient for obtaining a proper estimate of these parameters. harrison & platt (1986) found that high latitude phytoplankton populations exhibited lower val ues for p i . i,, and i, as well as higher ab values than phytoplankton of temperate latitudes. such differences were not always found in o u r data set. the median p: for all samples was 1.60 mgc (mgchl)-' h i . which is somewhere between t h e median values of 1.21 and 2.39 found for arctic and mid-latitudes in eastern c a n a d a . t h e barents sea is an area typically characterised by cold arctic waters in the north and relatively tem perate atlantic waters in the south. assuming that the overall median value for t h e barents sea represents an "average" value for temperate and cold waters. the data set was divided into two groups representing temperatures above and below 0°c respectively. this temperature is com monly used as a boundary between arctic and atlantic waters (loeng 1989). a single a n o v a was then applied t o determine if there were significant differences in the mean values of the p-1 parameters between t h e two subgroups. only p i and i , mean values were found t o be sig nificantly different at t h e 5% significance level. mean pi was 1.49 below 0°c and 2.01 above 0°c. this is as expected when it is taken into con sideration that the maximum photosynthetic rate of natural populations is usually a function of temperature. however, o t h e r factors such as species composition, cell size, and biomass might also have an influence o n these differences. mean i, values were 41 and 54 pmol m-' s-' for below and above 0°c samples, respectively, but this is probably mainly d u e t o variations in p i . means of the other parameters were not significantly different. mb. the o t h e r parameter determining i i . which in the eastern canadian arctic was slightly larger at high latitudes (harrison & platt 1986). showed similar mean values for both tem perature ranges in the barents s e a . although the range and median values of p: in the barents sea were of the same magnitude as those found in the eastern canadian arctic, there were large differences in the a* values between the two regions. assuming a solar irradiance conversion factor of 4.6 pmol m-'s-' ( w m ? ) ' , the canadian arctic values showed a median of 0 . 0 1 2 m g c ( m g c h l ) ' h ' (pmol m ? s i ) i compared t o 0.037 in the barents sea, a difference of 3 ~ . this obviously affected also the differences found between the median ik val ues from both regions, i.e. 78 p o l m-: s-' for the canadian arctic versus 43 for the barents sea. both data sets are large and include samples taken at different seasons, depths, and hydro graphical and biological conditions, so if the dif ferences in mb and ik a r e real, these comparisons suggest that the natural phytoplankton popu lations of the barents sea may b e more efficient in harvesting low light. t h e possibility of the effect of the different light sources utilised in the canadian arctic and the present work on ab and i k cannot be ruled o u t , since both parameters are influenced by t h e light spectral composition. the values of the p-i parameters from the barents sea a r e in the same range as those reported from several investigations carried out in the antarctic ocean (table 2 ) . all t h e experi ments in the antarctic ocean were carried o u t under controlled light conditions in laboratory incubators, with the exception of those of sak photosynthesis-irradiance relationships in the barents sea 109 1.73 i , i , i 0.0 a 0.15 0.10 c & i r 2 3 0.05 1.6 3.2 4.8 6.4 8.0 15 0.20 0.15 6 f 0.10 r 0.05 0 b 0.15 0.10 p t .k $ 3 3 0.05 c 0.044 d fig. 4a-e. frequency distribution of p-i parameters. numeri cal values represent mean values. 110 francisco rey table 2. p-l parameters of phytoplankton of selected polar areas ( m e a n \ ~n pdrenthcscs) n p: b b 1, i t rcfcrence antarctic isolated species 3 0 . g 9 . 3 0.0150.029 m 8 n rivkin & ( 5 . 5 ) (0.023) ( 6 1 ) putt (1987) antarctic natural population 7 2 8-3.7 0.064-0.075 4 2 4 9 rivkin early spring ( 3 . 1 ) (0.069) (45) e t at. (1989) antarctic natural population 20 0.2-2.4 0 . w . m 6 s 5 3 0 34-177 brightman winter ( 1 . 2 ) (0.026) (219) (54) & smith (1989) antarctic natural population 8 0 8-4.4 o . o o w . o j 9 16c-570 3 b l y o sakshaug & summer (2.6) (0.029) (331) (103) h o l m h a n s e n (1986) arctic natural population 21 6 1.2' 0.012' 36x' 7x' harrison & all seasons platt (1986) arctic natural population 232 0 % 7 3 o . o o u 1 163 i s 8 9 1 & 3 1 y this work all seasons ( 1 . 7 ) (13.044) clx)) (47) * median values units: p t : mgc (mgchl)-' h l nb: mgc (mgchl) ' h ' ( p o l m-' s ' ) l . i,. ik: pmol m-: s ' shaug & holm-hansen (1986) which were carried out under natural light on deck. relationships between the p-i parameters there is a pronounced correlation between p t and eb in both natural populations and laboratory cultures (harding e t al. 1981, 1985; maccaull & platt, 1977; harrison & platt 1986). this cor relation is also evident in the barents sea although the scattering of values is high (fig. 5 ) , especially where ab values were higher than 0.1. these values should be viewed with caution since they lie above the theoretical limit for 9 of phy toplankton (sakshaug & slagstad 1991 this volume). values of eb lower than 0.1 showed a slightly better correlation with p z at tem peratures above 0°c than at below 0°c. p:. as expected from theoretical consider ations. showed a slight positive correlation with both i,,, and i,. although there was a large spread in the data. u b , also as expected, was inversely correlated with the two above-mentioned light parameters (fig. 6 a and b ) . neither pw or eb were correlated with i b . p-i parameters and environmental factors previous studies have shown that it is possible to assess the effect of environmental variables on 8 7 6 5 o i 9 i i 1 0 0.05 0.10 0.15 0.20 q [ mgc(mgcnj* h-l (pnol m%-3-'1 fig 5 relationshlp bctween p e and 0' for samples taken helo% (circles) and abovc (squarea) 0°c photosynthesis-lrradiance relationships in the barents sea 11 1 lo00 t ly600 _1 m looo 1 800 4 0 1 2 3 4 5 6 7 0 a [mgc(mgqlljl i1 1 fig. 6a-b. relationships between two p-i parameters. 8 l 7 1 0 0.05 0.10 0.15 0.20 b a b i mgc(mgchl)-l h-' (ilmol ~ n ~ s ' ) ' ] i 1 t 0 10 20 30 a ophcal depth fig. 6a-b. relationships between two p-i parameters 1 i i i 0 10 20 30 c optical depth 1 i 1 0 10 20 30 b optical depth m m m i i 0 10 20 30 d optical depth fig. 7 a d . relationships between the optical depth and p-i parameters. 112 francisco rev photosynthesis through their effect o n the p-i parameters. p:. for example seems t o be. on an annual basis, predominantly controlled by tem perature, while mb is controlled by light history (platt & jassby 1976; harrison & platt 1980; sakshaug e t al. 1991). t h e same results have been found for phytoplankton growing in the laboratory (mortain-bertrand et al. 1988). t h e effect of temperature on the p-i parameters of natural phytoplankton populations of the barents sea have already been commented upon above. with regard to light. since irradiance data for the whole set of p-i data was not available. the optical depth (sampling depth mean light attenuation coefficient at sampling station) has been chosen as an index of the light conditions at t h e sampling depths. none of the p-i parameters (p:, wb, i,. il or i,,) showed a clear relationship t o optical depth. however. for all parameters except ik, there was a general trend for maximum observed tahk 3. simple rank correlation matrlx of photosynthetic and en\ironmental parameters. barents sea. 198&-1989. all coefficients based on 232 sample, pbmax alfa beta pbmax alfa beta imax ik ib optdepth temp salt no3 po4 s104 n 0 3 / s 1 0 4 chlor phaeop phaeop/chl ib optdepth temp salt no3 po4 s104 n 0 3 / s 1 0 4 chlor phaeop phaeopichl po4 9 0 4 n 0 3 ' s 1 0 4 chlor phaeop phaeop 'chl phaeop chl i ommj 0 4253 * 1 0 4067 ' i 0 4075 ' i 0 4948 ' i 0 oh22 0 1758 ' 2 0 2478 * i 0 0947 (1 0495 0 0394 0 1x20 ' 2 -0 0289 -0 0455 00111 -n 0528 ib i o(m i 1 0 3 5 5 -0 0427 0 0351 -0 0876 -0 i070 -0 0489 -0 0214 0 "9 0 0342 -0 (03005 po4 1 o(kx) u 7846 ' i 0 6543 ' i -0 0188 0 uo42 0 0 4 1 4 phaeop chl i oooo loo00 0 0397 -0 4264 ' i -0 5041 ' i 0 0489 -0 0616 0.0003 -0 0680 0 2075 '2 0.2052 '2 0 1809 ' 2 0 1355 '3 -0.1939 '2 -0.1183 0.1857 '1 optdepth 1 .oooo 0.0577 0.2656 ' 1 0 1666 '3 0.1577 '3 0.0410 0 3338 ' i 0.3246 ' i 0.3434 ' 1 -0.0214 sio4 1 .inw 0.2940 'i 0 .o?xlj 0 0107 0.0130 1 i m x m l -0 1389 '3 0 xxi ' i 0 xi69 ' i -0 11113 0 1360 ' 3 0 0u)l 0 114x4 ( i 0604 0 0718 -0 0107 -0 0075 -0 0463 0 0295 temp i w k k ) 0.3715 ' i -0.3182 * i 0 3413 ' i -i) 1321 * 3 -0.4496 * i -11.2348 * i -0 1973 ' 2 o.ni4o so3lsio4 i i x x x ) 0 2281 ' i 0.2131 '2 0.0075 imax i k i oooo 0.8178 ' i 0.3594 * 1 0 . i677 *3 0 . i083 -0.lxx9 * 2 -0.2119 '2 -0.0436 -0.1729 '2 0.1195 0.0741 0 . i z o x -n.1426 '3 salt 1 .o(mi 0.2499 ' i 0.2557 ' i 0.3240 * 1 0 1057 0.1789 '2 0.1595 '3 -0.1904 '2 chlor i .0uiwj 0.8084 * 1 -0.4951 ' i 1 .0000 -0.1426 *3 -0.1277 0.2315 ' i 0.1907 * 2 -0.1639 '3 0 . l x l l j '2 -0.01 17 -0.1871 '2 0.1249 0.0560 -0.1746 ' 2 no3 i .owxi 0.9525 ' 1 0.7665 *1 0.6965 ' i -0.0184 -0.0209 -0.0018 phaeop 1 . wo) 0.0143 * i = 99 y c ; confidence l e \ c l 99 o r < confidence h e 1 ' 7 = 95 ucr confidence h e 1 * 7 photosynthesis-irradiance relationships in the barents sea 113 values t o decrease with increasing optical depth (fig. 7a-d). although the trend is strongly influenced by eight samples obtained at optical depths larger than 10, these samples were col lected in two different years (1985 and 1987), under quite different biological conditions (see below). it can then be assumed that the observed trend is real and not influenced by some common factor. the lack of correlation between i k and depth in high-latitude samples has also been observed by other authors (platt et al. 1982; har rison & platt 1986) and has been ascribed, together with smaller depth-related differences of the other p-i parameters, to the difference in the development of density stratification in high latitudes areas as compared with temperate regions. in order to assess more qualitatively the influ ence of different environmental factors on the p-i parameters, a spearman rank correlation analysis was carried out on the whole data set (table 3). p: was positively correlated with temperature and silicate, but negatively correlated with the optical depth. ab was positively correlated with nutrients and a grazing index (phaeopigments/ chlorophyll) and negatively correlated with bio mass (chlorophyll). i, and ik were positively correlated with hydrographic variables as tem perature and salinity and negatively correlated with nutrients. when the data were analysed by seasons, some important differences appeared in the extent and nature of the environmental variables' effects on p:. for example during win ter (february-march), p: was negatively cor related with temperature but started t o show a positive correlation in spring (may-early june), exhibiting the strongest correlation during the summer months (july-august). the oppostie was seen in the correlation of p: with the optical depth, being positively correlated in winter and early spring (april) and negatively correlated dur ing spring and summer. the relationship between ab and other environmental factors did not show such marked differences from season to season. however, the relative strength of the different correlations changed from one season to another, with nutrients being more important in the spring and the grazing index during summer. with the exception of the influence of temperature on p t that occurred through all seasons, no other environmental variable showed such strong cor relation with the p-i parameters. the same lack of strong correlation between p-i parameters and environmental variables has been observed in other regions (harrison & platt 1986). a more quantitative assessment of the import ance of the environmental variables on p-i par ameters can be obtained b y using stepwise multiple regression analysis (harrison & platt 1980, 1986). for this purpose the following environmental parameters were selected: tem perature (as an hydrographic variable), chloro phyll (to represent phytoplankton biomass), nitrate (for nutrients), optical depth (for light conditions), the ratio between phaeopigments and chlorophyll (to represent grazing impact), and the ratio between nitrate and silicate (to represent main dominating phytoplankton groups; skjoldal & rey 1989). table 4 sum marises the results of these regression analyses using p k and ab as the dependent variables for the whole data set. temperature and the phaeo pigments/chlorophyll ratio were found to be the main variables controlling p:, although together they explained just 17% of the variation. the other four selected parameters explained only an additional 6%. for ab, the phaeopigment/ chlorophyll ratio explained 8.5% of the total vari ation with nitrate as a second important variable with about 3%. the rest of the variables accounted only for 3% of the total variation. as in the rank correlation analysis there were also large seasonal variations in the contribution of the different selected parameters in explaining variations of p: or ab. during winter (n = 8). table 4. stepwise multiple regression analysis of p i and ub on selected biological and environmental variables. based on 232 samples. p: variable temperature phaeop/chl optical depth nitrate chlorophyll nitrate/silicate (yb phaeop/chl nitrate optical depth temperature chlorophyll nitrate/silicate multiple r mr' 0.297 0.088 0.413 0.171 0.440 0.194 0.460 0.212 0.491 0.241 0.493 0.243 0.291 0.085 0.334 0.112 0.361 0.130 0.371 0.138 0.372 0.139 0.374 0. i40 delta r' f-ratio 0.088 22.28 0.083 23.58 0.023 18.24 0.019 15.26 0.029 14.32 0.002 12.06 0.085 21.23 0.027 14.40 0.018 11.3s 0.008 9.07 0.001 7.27 0.001 6.09 114 francisco rey nutrients and biomass accounted for about 7s% of the variations in pf)l while biomass and tem perature were responsible for about 28% of the variations i n early spring ( n = 27). in spring (n = 133), temperature and optical depth accounted for about 149% of the variations and the ratio phaeopigments/chlorophyll and temperature were responsible for 52% of the variations during summer (n = 64). these results suggest a seasonally increasing influence of temperature on the photosynthetic capacity of the phytoplankton in the barents sea. this is probably related t o the increasing difference in temperature between the shallow upper mixed layer and the layers below the pycnocline that occurs throughout the spring and summer, especially in waters that have been covered by ice during winter. i n the case of ab. biomass and the ratio phaeopigments/chlorophyll contributed 61 % and 35% of the variation, respectively, during winter and early spring. in spring the variables respon sible for most of the variation were the optical depth and nitrate, accounting for just 10%. i n summer, the optical depth, the ratio phaeopigments/chlorophyll, and temperature contributed about 30% to the variation. the importance of the light history (i.e. optical depth) in controlling ab. as it has been found in other investigations (platt & jassby 1976). was not evi dent until spring and was almost negligible on a several year basis. the same lack of relationship has been found earlier (harrison & platt 1986). the relatively large importance of the ratio phaeopigments/chlorophyll as one of the vari ables determining a sustantial part of the vari ations of p t and ab, both on an annual and a seasonal basis, has not been described before for arctic phytoplankton, probably because it has not been included in the analyses. the relative amount of phaeopigments has been suggested as an index of grazing pressure by herbivore zooplankton on phytoplankton (shuman & lor enzen 1975; welschmeyer & lorenzen 1985), but little is known about how it can affect phy toplankton photosynthesis. most probably the effect is indirect, either through the recycling of nutrients or the reduction of biomass. cbte & platt (1983). working in a small marine inlet, also found a strong positive correlation between the phaeopigment/chlorophyll ratio and p and emphasised the importance of nutrient recycling in that coastal area. kristiansen & lund (1989) found that in the barents sea ammonium was the most important nitrogen source for phytoplank ton in late spring and summer. this period is characterised by a well-developed pycnocline that gives rise to an upper oligotrophic layer with phytoplankton growth supported by remin tubk 5. mean values and standard deviation (in parentheses) of photosynthetic parameters and environmental variables from two biological situations in the barents sea. depth strata temperature chlorophyll p! p', a n a' 1, i k * ] 0 2 'lo-' m a y j u n e 1987 10 metre n = 12 30 metre n = 7 >40 metre n = i ? a u g u t i985 10 metre n = 8 2g30 metre n = r 31-40 metre n = 8 > 4 l metre n = j 0.70 (-1.48-2 12)' 1.10 (-0.61-2.05)' u.98 (-0.7%?.03) 3.81 0 2 0 (-1.7.lh.48)' -0.91 (-1.78-2.83)' 0.y4 (0 73-1.09)' (2.03-5.39)' 2.638 (2.010) 3.571 (1.138) 3.283 ( i ,362) 0.346 (0.176) 0.886 (0.492) 1.789 ( 1 . 4 5 1 ) 0.823 ( 0 . m ) 1.452 1.455 (0.751) 0.962 (0.549) (n.708) 1.735 (0.365) 1.295 (0.480) 1 283 ( i .2s3) 0.y37 (0.171) 2.53 ( 1 . 2 4 ) 2.56 (1.31) 1.68 (0.96) 2.34 2.46 (0.87) 3.40 (3.67) 4.05 ( i .01) (0.49) 0.0244 0.0275 (0.0133) 0.0206 (0.0085) (0.0139) 0.0348 (0.0090) 0.0347 (0.01 07) 0.0561 (0.0458) 0.0526 (0.0 186) 0.43 (0.24) 0.48 (0.23) 0.36 (0.15) 0.47 (0.12) 0.66 (0.17) 1.48 (1.37) 2.31 (0.y7) 214 (37) 1 89 (103) 1 1 1 (39) 93 ( 1 3 ) range. photosynthesis-lrradiance relationships in the barents sea 115 eralised nutrients (rey & loeng 1985). under these conditions, the effects of grazing on nutrient recycling could be of major importance in con trolling phytoplankton photosynthesis in the bar ents sea after the spring bloom and the strengthening of the pycnocline. the fact that phytoplankton in this area is not severely nitrogen limited (kristiansen & lund 1989) supports this idea. on an overall basis neither biomass, nutrients, nor phytoplankton species composition seemed to have any major influence on controlling the variations in the p-i parameters. the same was observed by harrison & platt (1986) while work ing with phytoplankton populations in the eastern canadian arctic. these authors found their results to be consistent with nutrient studies that showed no signs of nutrient-stress. in general, the results of this analysis of the p i parameters in the barents sea confirm previous findings in other arctic regions (harrison & platt 1986), i.e. the general lack of strong correlation between the p-i parameters and covarying environmental factors and the clear correlation between pe and ab. the main difference was that light did not have a clear role in determining variations in the photosynthetic efficiency, a", as it had been previously suggested. however, it is inevitable that when working with such large sets of data some single relationships become masked and do not appear as significant. this is demon strated in table 5 , where p-i parameters have been summarised along with some environmental factors from two different biological situations: in the spring of 1987 at the end of the phytoplankton bloom, dominated by the prymnesiophyte phaeo cystis pouchetii (wassmann et al. 1990); and in the summer of 1985 after oligotrophic conditions have developed in the upper layer and a strong subsurface chlorophyll maximum has developed (rey unpubl. data). during the spring situation, there were no differences in the p-i parameters with depth in the euphotic zone, with the excep tion of i, that decreased with depth. below the euphotic zone (>40m depth), only small dif ferences in the p-i parameters were observed. this indicates that no adaptation to low irradiance had occurred, probably due to a strong vertical mixing. in the summer the situation was com pletely different. the chlorophyll normalised p i parameters were similar throughout the upper 30 metres, but they showed a sharp increase in ab at the region of the subsurface chlorophyll maximum and below, while p z , i, and ik decreased with depth. this supports the findings of beardall & morris (1976) that a diatom growing at low intensities has enhanced ability to utilise sub-optimal intensities and reduced ability to util ise saturating levels. the most dramatic differ ence, however, was found in the carbon normalised p-i parameters. both p: and ac increased strongly with depth below the euphotic zone, suggesting that one of the mechanisms by which the phytoplankton adapted to the low light levels was increasing their cellular concentrations of photosynthetic pigments. these findings illus trate small scale effects on the p-i parameters, such as light adaptation, which may not always be revealed in a global analysis as the one made here. acknowledgements. -sincere thanks to f. mora for his help in collecting and processing the data. my gratitude also to b. stensholt for advice in statistical matters and to e. sakshaug for providing valuable comments. thanks are also due to two anonymous reviewers for their helpful suggestions. this work was partially supported by the norwegian fisheries research council. references beardall, j. & morns. i . 1976: the concept of light intensity adaptation in marine phytoplankton: some experiments with phaeodacrylum tricornutum. mar. biol. 37, 317-387. brightman, r. i. & smith. w . 0.. jr. 1989: photosynthesis irradiance relationships of antarctic phytoplankton during austral winter. mar. ecol. prog. ser. 5 3 , 143-151. cbt6, b. & platt. t. 1983: day-to-day variations in the spring summer photosynthetic parameters of coastal marine phy toplankton. limnol. oceanogr. 28. 32ck344. feyn. l.. magnussen. m. & seglem. k. 1981: automatic analy sis of nutrients with 'on-line' data treatment. a presentation of the construction and performing of the system in use at the institute of marine research vessels and laboratory. fisken hau., serie 8. 1981(4), 1-39. harding, l. w . . j r . . meeson. b. w.. prezelin. b. b. & sweeney. b. m. 1981: die1 periodicity of photosynthesis in marine phytoplankton. mar. biol. 6 1 , 95-105. harding. l. w . , jr., meeson. b. w. & fisher, t. r.. j r . 1985: photosynthesis patterns in chesapeake bay phytoplankton: shortand long-term responses of p-i curve parameters to light. mar. ecol. prog. ser. 26. 99-1 11, harrison, w. g. & platt. t. 1980: variations in assimilation number of coastal marine phytoplankton: effects of environ mental co-variates. 1. piankton res. 2, 249-260. harrison, w. g. & platt. t. 1986: photosynthesis-irradiance relationships in polar and temperate phytoplankton popu lations. polar biol. 5 . 153-164. kristiansen, s. & lund, b.aa. 1989: nitrogen cycling in the barents sea-i. uptake of nitrogen in the water column: deep sea res. 36, 255-268. 116 franci.sco rey loeng. h. 1989: ecological featurcs of the barents sea. pp. 3 m 1 in rey. l. & alexander. v. (eds.): proceedings of rhe surh conference ofrhe cofnlre arcrique l n f e r ~ i a r i o n a l , 13 i5 may 1985. e . j. brill. leiden. maccaull. w. a. & platt. t. 1977: die1 variations i n the photosynthetic parameters of coastal marine phytoplankton. l i m n o l . oceanogr. 22. 73-73 1 mortain-bcrtrand. a . . dcscolas-gros. c. & jupin. h. 1988: growth. photosynthesis and carbon metabolism in the tem perate marine diatom s k d e r o n e m a cosfafurn adapted to loa temperature and l o w photon-flux density. m a r . biol. 100. 135-1.11. neldcr. j . a. & mead. r . 1965: a simplex method for function minimization. cornpurer 1. 7. 30b31.7. platt. t . & jasshy. a . 1976: the relationship between photo synthesis and lrght for natural assemblages of coastal marine phytoplankton. j . p h w o l 12. 421-430. platt. t.. gallegos. c. l & harrison. w . g . 1080: photo inhibition of photosynthesis i n natural assemblages of marine phvtoplankton j . mur. res. 38. w7-701. platt. t . harrison. w . g . . irwin. b.. horne. e. p. & gallegos. c. l. 1982: photosynthe5is and photoadaptation of marine phytoplankton in the arctic. deep-sea res 29. 115y-1170. rey. f & loeng. h . 19x5: the influence of ice and hydro graphic conditions on the development o f phytoplankton in the barentssea. pp. 4%63 in gray. j. s. & christianscn. m . e. (eds.): marine biology of polar regions a n d €ffecfs of srress o n marine o r g a n u m s . john wile? & sons ltd.. england. rivkin. r . b. & putt. m. 1987: photosynthesis and cell division by antarctic microalgae: comparison of benthic. planktonic and ice algae. j. p h y d 23. 223-229. rivkin. r. b.. putt. m . . alexander. s. p.. meritt. d. & gaudet. l. 1989 biomass and production in polar planktonic and sea ice microbial communities: a comparative study. m a r . biol. 101. ?7-l283 sakshaug. e . & holm-hansen. 0. 1986: photoadaptation in antarctic phytoplankton: variations in growth rate. chemical composition and p versus i curves. 1. piankron res. 8 . 459 473 sakshaug. e . & slagstad. d. 1991: light and productivity of phytoplankton in polar marine ecosystems: a physiological view. pp. 6%85 i n sakshaug. e.. hopkins. c . c. e. & britsland. n . a . (eds.): proceedings of the pro mare sym posium on polar marine ecology. trondheim. 12-16 may 1990. polar research 1 0 ( / ) . sakshaug. e.. johnsen. g . . andresen, k . & vernet. m. 1991: modeling of light-dependent algal photosynthesis and growth: experiments with the barents sea diatoms thal assiosira nordenskioeldii and chaeroceros fitrcellarus. d e e p sea res. 38. 41-30, skjoldal. h. r. & rey. f. 1989: pelagic production and varia bility of the barents sea ecosystem. pp. 241-286 in sherman, k . & alexander. l. m . (eds.): b i o m a s s y i e l d s a n d g e o g r a p h y o f large marine ecosvsrems. aaas selected symposium 11 1, westview press. inc.. colorado. usa. shuman. f. r. & lorenzen. c . j . 1975: quantitativedegradaton of chlorophyll by a marine herbivore. limno1. oceanogr. 20, 5ru-585 wassmann. p . . verncl, m . . mitchell. b. g. & rey. f: 1990. mass sedimentation of phaeocysris p o u c h e f i i in the barents sea. mar. ecol. p r o g . ser. 66. 183-195. welschmeyer. n . a . & lorenzen. c. j . 1985: chlorophyll budgets: zooplankton grazing and phytoplankton growth in a temperate fjord and the central pacific gyre. l i m n o l . oceanogr. 30. 1-21 doi:10.3402/polar.v33.20206 r e s e a r c h / r e v i e w a r t i c l e benthic foraminifera from the lower jurassic transgressive mudstones of the south-western barents sea*a possible high-latitude expression of the global pliensbachian�toarcian turnover? silvia hess,1 jenő nagy1 & gitte vestergaard laursen2 1 department of geosciences, university of oslo, po box 1047, blindern, no-0316 oslo, norway 2 statoil asa, no-4035 stavanger, norway keywords barents sea; foraminifera; marginal marine environments; early jurassic; pliensbachian�toarcian turnover. correspondence silvia hess, department of geosciences, university of oslo, po box 1047, blindern, no-0316 oslo, norway. e-mail: silvia.hess@geo.uio.no abstract the lower jurassic section of two commercial wells (7119/12-1 and 7119/12-2), drilled in the hammerfest basin, was analysed for foraminiferal assemblages in order to reconstruct palaeoenvironmental changes. foraminifera occurred singularly in transgressive mudstone intervals of the stø formation in well 7119/12-1. high-energy marginal marine and offshore sandstones and freshwater sandand mudstones were barren of foraminifera. three distinct foraminiferal assemblages could be distinguished. they contain exclusively agglutinated taxa and have extremely low species diversities, indicating restricted environmental conditions. the main restricting factor was low salinity in strongly delta-influenced waters. foraminiferal assemblage 1 is developed at the base of the stø formation and suggests transgressive, extremely hyposaline lagoonal conditions. assemblages 2 and 3 occur in hyposaline prodelta shelf mudstones of the stø formation and reveal increased diversities in major local transgressive phases. the foraminiferal assemblages indicate pliensbachian� toarcian ages. the mudstones of the stø formation are regarded as a local expression of the global pliensbachian�toarcian turnover recording regional transgressive developments in the toarcian. foraminifera have been used in numerous studies as palaeoenvironmental indicators in ancient marine environments. in siliciclastic marginal marine and coastal (paralic) systems, the palaeoenvironmental application of this biota is much more infrequent even though these environments, which contain coal and petroleum reservoirs, have high industrial potential. in the boreal realm, biofacies studies of paralic foraminiferal assemblages have recently intensified, resulting in several papers (e.g., nagy & johansen 1991; nagy & seidenkrantz 2003; nagy & berge 2008; nagy et al. 2011). the early jurassic was a period of considerable environmental changes resulting in marine biotic turnover events which are also documented at high latitudes (e.g., nikitenko & mickey 2004; zakharov et al. 2006). successions of organic-rich mudstones and shales associated with a negative carbon isotope excursion developed during transgressive phases in the lower toarcian (suan 2011) and coincide with biotic turnover events. this paper presents the results of an investigation of early jurassic foraminiferal assemblages from two commercial wells drilled in the hammerfest basin in the south-western barents sea (fig. 1). our study concentrates on lower jurassic deposits of the stø and nordmela formations, which compose the uppermost part of the kapp toscana group (fig. 2). this sand-dominated succession is widely developed on the barents sea shelf (including the svalbard archipelago) where it has a high petroleum reservoir potential, but is rather poor in agesignificant fossils. (page number not for citation purpose) polar research 2014. # 2014 s. hess et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 20206, http://dx.doi.org/10.3402/polar.v33.20206 http://www.polarresearch.net/index.php/polar/article/view/20206 http://dx.doi.org/10.3402/polar.v33.20206 quantitative foraminiferal assemblage analyses are integrated with sedimentological data to enhance the understanding of depositional conditions of the deltainfluenced, marginal marine succession of the lower jurassic. in addition, information from the distribution of modern foraminiferal faunas is used. such information reflecting environmental parameters (i.e., food supply, oxygen content, salinity, sediment type, water depth) is useful in order to enhance the understanding of past analogue environmental conditions (e.g., scott et al. 1983). the foraminiferal faunas of the analysed succession are characterized by low diversities and consist entirely of agglutinated taxa. they reveal close similarities to agglutinant-dominated assemblages occurring in jurassic deposits of several northern european and arctic areas, as recorded from svalbard (løfaldi & nagy 1980; nagy et al. 2011), arctic canada (souaya 1976; wall 1983), alaska loppa high finnmark platform t ro m sø b a si n hammerfest basin bjørnøya basin h ar st ad b as in norsel high v es le m øy h ig h s e n ja r id g e t ro m sf in n m a rk f a u lt c o m p le x må sø y f au lt c om ple x ny sle pp f au lt c om ple x n or dk ap p ba si n samson dome 0 45 km alta n o r w a y 19°e 73°n 72°n 71°n 17°e 18°e 19°e 20°e 21°e 22°e 23°e 24°e 20°e 21°e 22°e 23°e 24°e 25°e 26°e 27°e 72°n 71°n 70°n http://www.npd.no/factmaps bjarmeland platform deep cretaceous basins shallow cretaceous basins cretaceous highs terraces and intrabasinal highs mesozoic platforms paleozoic highs studied wells 7119/12-1 7119/12-2 fig. 1 study area map of the south-western barents sea shelf with the well locations (modified from the norwegian petroleum directorate’s fact map). lower jurassic foraminifera s. hess et al. 2 (page number not for citation purpose) citation: polar research 2014, 33, 20206, http://dx.doi.org/10.3402/polar.v33.20206 http://www.polarresearch.net/index.php/polar/article/view/20206 http://dx.doi.org/10.3402/polar.v33.20206 (tappan 1955), siberia (nikitenko & mickey 2004) and the northern north sea basin (nagy 1985a,b; nagy & johansen 1991; nagy & seidenkrantz 2003). the kapp toscana group in the hammerfest basin the kapp toscana group is a siliciclastic sediment succession attaining a thickness of 2000 m in the hammerfest basin, south-western barents sea. the succession was deposited in offshore shelf to dominantly coastal and deltaic environments with transport direction from southeast, east and north-east (mørk et al. 1999). in this basin, the group is subdivided into the following five formations, in ascending order (ages and descriptions from dalland et al. [1988]; fig. 2). the snadd formation (ladinian to norian) consists mainly of shales with subordinate siltstones and sandstones, and was deposited under offshore shelf conditions. the fruholmen formation (norian to rhaetian) comprises mudstones and sandstones ascribed to open shelf, coastal to fluvial environments. the tubåen formation (rhaetian to sinemurian) contains thick sandstone bodies and thin mudstone intervals interpreted as estuarine deposits. the nordmela formation (sinemurian to late pliensbachian) consists predominantly of alternating sandand mudstones. minor coal beds and numerous rootlet horizons are present (fig. 3). the main facies associations recognized in this formation are distributary channels, interdistributary bays, back-barrier lagoons and tidal flats. lacustrine mudstones also occur. it is assumed that the lagoonal, interdistributary bay and intertidal strata were deposited under hyposaline conditions. the stø formation (late pliensbachian to bajocian) is dominated by fineto coarse-grained sandstones alternating with subordinate mudstone intervals. the sandstones were deposited mainly in high-energy shoreface environments or as offshore bars. some of the mudstones are probably formed in low energy marginal marine settings such as tidal flats, lagoons and interdistributary bays. regionally extensive mudstone horizons represent transgression events depositing offshore marine facies between more proximal marine sandstones. such transgressive mudstones are typical for the upper part of the formation (fig. 3). most sections show fining-upward parasequences and common bioturbation. a sedimentological study of the nordmela and stø formations carried out by olaussen et al. (1984) included the two wells analysed in this paper. the stratigraphy and regional development of the deltaic systems dominating the kapp toscana group are further discussed by van veen et al. (1992) and riis et al. (2008). material and methods the two wells examined are located in the south-western part of the hammerfest basin: well 7119/12-1 (n 71806?07.99??, e 19847?40.29??) and well 7119/12-2 (n 71800?51.81??, e 19858?20.81??; fig. 1). the wells were drilled to obtain information about the hydrocarbon reservoir properties of jurassic sandstones. the sampled intervals of the nordmela and stø formations range from 2670 to 2850 m core depth in well 7119/12-1 and from 1470 to 1690 m in well 7119/12-2. a total of 68 core samples were prepared for foraminiferal analyses: 57 from well 7119/12-1 and 11 from well 7119/12-2. in total, 36 samples contained foraminifera. all are from the stø formation of well 7119/12-1. altogether 32 samples were barren of foraminifera. they are the following: all 11 samples taken from the nordmela formation of well 7119/12-2; 7 samples from the nordmela formation of well 7119/12-1; 14 samples of the stø stage u p p e r tr ia ss ic l o w e r ju ra ss ic m . j u ra ss ic carnian norian rhaetian hettangian sinemurian pliensbachian toarcian aalenian bajocian bathonian g ro u p k a p p t o sc a n a m ya e p o c h 225 220 215 210 205 200 195 190 185 180 175 170 165 formation snadd fruholmen tubåen nordmela stø fig. 2 stratigraphic overview of the kapp toscana group in the hammerfest basin. s. hess et al. lower jurassic foraminifera citation: polar research 2014, 33, 20206, http://dx.doi.org/10.3402/polar.v33.20206 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20206 http://dx.doi.org/10.3402/polar.v33.20206 2830 2800 2840 2750 2740 2730 2720 2710 2670 2810 2820 2790 2760 2770 2780 2700 2690 2680 1 2 3 4 17 18 19 46 47 48 49 50 52 51 53 54 55 56 57 s ta g e l a te p lie n sb a ch ia n t o a rc ia n a a le n ia n e p o ch e a rl y ju ra ss ic m id d le j u ra ss ic n o rd m e la s tø l ith o lo g y s a m p le co re d e p th ( m ) f o rm a tio n structures depositional environment gamma ray beach or bar deposits prodelta shelf mudstone storm generated beds shoreface and foreshore sand bars lagoonal deposits estuarine deposits, tidal channels, marshcoastal plain? offshore transition offshore transition offshore transition offshore bar offshore bar foram.assemblage 3 foram.assemblage 1 offshore bar prodelta shelf mudstone foram.assemblage 2 cl si sand fvf m vc gc c c cross stratification parallel stratification low angle stratification bioturbation rootlets solution seams/ incipient stylolites stylolites mudstone sandstone legend: c coal fig. 3 age relationships, lithological log and facies interpretation of the analysed interval of well 7119/12-1. the illustration is based on olaussen et al. (1984) and the present study. lower jurassic foraminifera s. hess et al. 4 (page number not for citation purpose) citation: polar research 2014, 33, 20206, http://dx.doi.org/10.3402/polar.v33.20206 http://www.polarresearch.net/index.php/polar/article/view/20206 http://dx.doi.org/10.3402/polar.v33.20206 formation of well 7119/12-1. the majority of samples were taken from mudstone layers, usually dark in colour. the laboratory processing of samples required an unexpectedly intensive treatment owing to the high degree of diagenetic cementation (also reflected by common styloliths in the sandstones). to achieve disaggregation of the mudstones, the samples were first soaked in kerosene for approximately 30 min. after decanting the kerosene, the sediments were boiled in a solution of sodium hydroxide (naoh). thus, the disintegrated material was washed through sieves with �63 mm mesh size and dried at 408c. if necessary, the procedure was repeated to achieve sufficient disaggregation. the dried residue �90 mm was analysed for its foraminiferal content. from the residue, at least 300 foraminiferal tests (if available) were picked and mounted on micropalaeontological slides, which are stored at the department of geosciences in oslo. the foraminiferal abundance was calculated as the number of individuals per 10 g of dry sediment. faunal diversity is expressed both by the shannon-wiener h(s) and fisher a diversity indices (fisher et al. 1943; shannon 1948). most foraminiferal tests were compressed by diagenetic compaction of the sediments. therefore, some species are kept in open nomenclature. the taxonomical identifications are mainly based on earlier descriptions and on subsequent papers by nagy & johansen (1991) and nagy & basov (1998). additionally, the organic carbon (toc) and carbonate content of the well sections were measured with a cr412 carbon analyzer (leco corporation, st. joseph, mi, usa). benthic foraminiferal assemblage features of the stø formation general characteristics of assemblages in total, 3581 benthic specimens were picked and used in the analyses. only agglutinated foraminifera are present in the sample set. fourteen taxa are identified and listed in table 1. the most common species are trochammina squamataformis, ammodiscus pseudoinfimus forma granulata and kutsevella memorabilis. they are often accompanied by bulbobaculites vermiculus, b. strigosus, thuramminoides sp., lagenammina inanis, psammosphaera sp. and reophax metensis. in the examined part of well 7119/12-1, three biotic events are distinguished which reflect transgressive encroachments of marine shelf conditions in the stø formation (fig. 3). the dark mudstone intervals deposited during these inundations show a range of foraminiferal abundance between 41 and 2 individuals per 10 g dry sediment (fig. 4). the species diversities are generally low with fisher a values below 5, indicating restricted environmental conditions (fig. 5). foraminiferal assemblage 1 the transitional beds between the nordmela and stø formations were checked for foraminifera by processing nine samples from the interval 2810 and 2845 m core depth. only a single sample from the lower stø formation contains foraminifera (sample 50, 2811.6 m core depth). just 15 individuals were found in 10 g of dry sediment (fig. 4). the assemblage is composed entirely of agglutinated taxa and has an extremely low diversity; only three taxa are present (fisher a index �0.6). the assemblage is nearly monospecific with ammodiscus pseudoinfimus forma granulata as the most abundant species (fig. 6). the sample was taken from a finegrained silty mudstone interval that appears to represent a minor flooding event. foraminiferal assemblage 2 the middle mudstone interval containing foraminiferal assemblages 2 in the stø formation is recognized in samples 19�46, which are located between 2729.3 and 2738 m core depth (fig. 4). this interval is split by a silty�sandy bed into two foraminifera-bearing subunits (samples 19�29 from 2729.3 to 2732.3 m core depth, and samples 34�37 from 2734.1 to 2737.3 m core depth). table 1 all foraminiferal taxa identified in this study are listed alphabetically. generic classification follows loeblich and tappan (1988). open nomenclature is used for taxa that could not be identified to species level. ammodiscus pseudoinfimus forma granulata gerke & sossipatrova 1961 ammodiscus glumaceus gerke & sossipatrova 1961 bulbobaculites vermiculus nagy & seidenkrantz 2003 bulbobaculites strigosus (gerke & sossipatrova 1961) �ammobaculites strigosus gerke 1961 kutsevella memorabilis (scharovskaja 1958) lagenammina inanis (gerke & sossipatrova 1961) �saccammina inanis gerke & sossipatrova 1961 psammosphaera sp. recurvoides sp. reophax metensis franke 1936 reophax sp. spiroplectammina sp. thuramminoides sp. trochammina squamataformis kaptarenko-chernousova 1959 verneuilinoides subvitreus nagy & johansen 1991 s. hess et al. lower jurassic foraminifera citation: polar research 2014, 33, 20206, http://dx.doi.org/10.3402/polar.v33.20206 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20206 http://dx.doi.org/10.3402/polar.v33.20206 4 6 5 7 9 8 10 12 11 13 15 14 16 17 toc (%) 2 4 abundance (indiv./10 g) 20 40 2 4 sa m pl es fisher α index fa 3 flooding event major flooding interval fa 3 depositional conditions hyposaline prodelta 19 21 20 22 24 23 25 27 26 28 30 29 31 33 32 34 toc (%) 2 4 abundance (indiv./10 g) 20 40 2 4 35 36 37 38 39 40 41 42 43 44 45 46 sa m pl es fisher α index fa 2 flooding event fa 2 major flooding interval maximum flooding interval depositional conditions hyposaline prodelta barren barren 49 51 50 52 54 53 55 57 56 toc (%) 2 4 abundance (indiv./10 g) 20 40 fisher α index 2 4 7.9 sa m pl es fa 1 flooding event fa 1 minor flooding depositional conditions strongly hyposaline lagoon barren barren2830 2800 2840 2750 2740 2730 2720 2710 2670 2810 2820 2790 2760 2770 2780 2700 2690 2680 1 2 3 4 17 18 19 46 47 48 49 50 52 51 53 54 55 56 57 s ta ge la te p lie ns ba ch ia n t oa rc ia n a al en ia n e po ch e ar ly j ur as si c m id dl e ju ra ss ic n or dm el a s tø li th ol og y s am pl e co re d ep th ( m ) f or m at io n fig. 4 lithological features, main foraminiferal distribution proxies and foraminifera-based facies interpretation of the analysed interval of well 7119/ 12-1. fa stands for foraminiferal assemblage and toc stands for organic carbon. lower jurassic foraminifera s. hess et al. 6 (page number not for citation purpose) citation: polar research 2014, 33, 20206, http://dx.doi.org/10.3402/polar.v33.20206 http://www.polarresearch.net/index.php/polar/article/view/20206 http://dx.doi.org/10.3402/polar.v33.20206 the foraminiferal abundance in this mudstone interval ranges between 2 and 41 individuals per 10 g of dry sediment (fig. 4), reaching maximum values in the upper subunit (sample 20). the fisher a diversities are low, with an average of 1.7. simple species numbers range between 4 and 9. the assemblages contain only agglutinated taxa. the dominant species in both subunits is trochammina squamataformis, which is accompanied by ammodiscus pseudoinfimus forma granulata and kutsevella memorabilis (fig. 6). foraminiferal assemblage 3 the foraminiferal assemblage 3 is characteristic for the samples 4�17 from 2709.7 to 2714.3 m core depth in the upper mudstone interval of the stø formation. foraminiferal abundances range between 2 and 35 individuals per 10 g dry sediment. the diversities are low; showing species numbers ranging between 3 and 10 and an average fisher a index of 1.6 (fig. 4). dominant species include trochammina squamataformis, ammodiscus pseudoinfimus forma granulata, bulbobaculites vermiculus and kutsevella memorabilis (fig. 6). foraminiferal facies reflecting depositional conditions general aspects and modern analogues a sedimentological framework of the lower to middle jurassic deposits of well 7119/12-1 was provided by olaussen et al. (1984) with assessments of the depositional conditions. this sand-dominated succession was deposited in several environmental settings ranging from delta-influenced shelf mudstones through shoreface sands (stø formation) to tidal flat/coastal plain finegrained sandstones with thin coal layers and rooted horizons (nordmela formation). as mentioned above, 32 samples treated for foraminiferal analysis were barren. mudstone samples containing no foraminifera may represent freshwater deposits. marginal marine and offshore sandstones are assumed to have been deposited in hyposaline waters. the foraminiferal assemblages of the three mudstone intervals are typified by entirely agglutinated species composition, extremely low diversities, and the dominance of ammodiscus and trochammina taxa. the low fisher a indices (all b5) suggest restricted environmental conditions in which low salinity or oxygen depletion were the potentially main controlling factors (nagy et al. 2011), as indicated by modern analogues (fig. 5). a compilation of foraminiferal distribution patterns in modern environments (murray 1973) demonstrates that hyposaline conditions are typified by fisher a indices lower than 5. low diversity assemblages dominated by agglutinated taxa such as ammodiscus and trochammina are known from some modern brackish environments, although these genera also occur in normal marine habitats (murray 1991). of particular interest is the dominance of ammodiscus and trochammina taxa in some modern marginal marine environments with bottom water hypoxia developed in a salinity-stratified water column. foraminiferal taxa adapted to such conditions often show reduced test dimensions (see nagy et al. 2010 and references therein). this feature was used for the recognition of hypoxic conditions in upper triassic to lower jurassic deposits of the north atlantic margin by nagy et al. (2010). environments of the nordmela formation the investigated well sections of the nordmela formation consist of fine-grained sandstones and siltstones with interbedded mudstone intervals. several parasequences show fining upwards trends and might represent tidal channel fills. in some intervals in well 7119/12-1 (2845 to 2820 m core depth) some rootlet horizons and thin coal seams are present. no foraminifera were found in any sample from the nordmela formation. these barren samples and the presence of rootlets suggest extremely brackish tidal flat to coastal plain conditions. restricted conditions normal marine shelf conditions 0.5 1.0 1.5 2.0 2.5 3.0 1 2 3 4 5 6 7 8 fisher α h (s ) fig. 5 foraminiferal sample plot of fisher a and h(s) diversity indices from the analysed interval of well 7119/12-1. foraminiferal assemblages 1, 2 and 3 are represented by a square, dots and diamonds, respectively. s. hess et al. lower jurassic foraminifera citation: polar research 2014, 33, 20206, http://dx.doi.org/10.3402/polar.v33.20206 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20206 http://dx.doi.org/10.3402/polar.v33.20206 environments of the stø formation the sedimentary succession composing the stø formation reveals shallow marine environments with transgressive trends. the thick and homogeneous sandstones with no or sparse bioturbation are interpreted as shoreface and foreshore sand bars (fig. 3). fine-grained sandstones, commonly silty, often bioturbated and locally with storm beds are ascribed to the offshore transition zone. the sandstones are barren of foraminifera. s a m p le s f o rm a ti o n s tø n o rd m e la 1 9 8 7 6 5 4 3 2 10 18 17 16 15 14 13 12 11 19 21 28 27 26 25 24 23 22 20 29 30 38 37 36 35 34 33 32 31 39 40 56 54 52 50 48 46 44 42 41 43 57 55 53 51 49 47 45 s ta g e l a te p lie n sb a ch ia n t o a rc ia n a a le n . f o ra m in ife ra l a s s e m b la g e 1 f o ra m in ife ra l a s s e m b la g e 2 f o ra m in ife ra l a s s e m b la g e 3 k u ts e ve lla m e m o ra b ili s p sa m m o sp h a e ra s p . a m m o d is cu s p se u d o in fim u s fo rm a g ra n u la ta b u lb o b a cu lit e s ve rm ic u lu s b u lb o b a cu lit e s st ri g o su s l a g e n a m m in a in a n is r e o p h a x m e te n si s t ro ch a m m in a s q u a m a ta fo rm is r e p h a x sp . s p ir o p le ct a m m in a s p . v e rn e u ili n o id e s su b vi tr e u s r e cu rv o id e s sp . t h u ra m m in o id e s sp . a m m o d is cu s g lu m a ce u s ≤ 1 indiv./ 10 g ≤ 2 > 20 ≤ 10 ≤ 4 barren ≤ 20 fig. 6 stratigraphic distribution of foraminiferal taxa through the analysed interval of well 7119/12-1. lower jurassic foraminifera s. hess et al. 8 (page number not for citation purpose) citation: polar research 2014, 33, 20206, http://dx.doi.org/10.3402/polar.v33.20206 http://www.polarresearch.net/index.php/polar/article/view/20206 http://dx.doi.org/10.3402/polar.v33.20206 the three main mudstone intervals containing the described foraminiferal assemblages 1�3 represent transgressive pulses superimposed on the overall transgressive development of the formation (fig. 3). the lowermost fine-grained and bioturbated siltstone�mudstone beds of the stø formation represent a transgressive event in a still coastal near environment. this is confirmed by the presence of a low diversity foraminiferal assemblage in sample 50 of well 7119/12-1 (foraminiferal assemblage 1). the nearly monospecific composition of this assemblage suggest slightly increased salinity in a possibly lagoonal environment. the upper two mudstone intervals are referred to prodelta shelf environments. the siltstone bed appearing in the middle of the lower mudstone interval is interpreted as a storm deposit, which explains why it is barren of foraminifera (fig. 4). the water masses of the shelf area with prodelta mud deposition were hyposaline as indicated by the low diversity agglutinated foraminiferal assemblages 2 and 3. in accordance with this, the assemblages include ammodiscus, trochammina, bulbobaculites and kutsevella among the dominant genera. development of hyposaline conditions in the prodelta shelf outside the kapp toscana deltas is in accordance with the large dimensions of this deltaic system, as it is apparent from the reconstructions presented by van veen et al. (1992) and riis et al. (2008). as mentioned above, size reduction of foraminifera is regarded as an adaptation to low oxygen conditions. by using taxa of ammodiscus and trochammina, this feature is applied as a proxy for oxygen depletion by nagy et al. (2010) in several upper triassic to middle jurassic sections including an interval of the ragnarok formation of the mjølnir structure (central barents sea). in the foraminiferal assemblages 2 and 3, these genera show no size reduction although a small degree of hypoxia is expected owing to the somewhat increased toc content of the mudstone samples (fig. 4). it seems probably the oxygen depletion was too small to cause a test size reduction. the presence of bioturbation in the mudstones also suggests that oxygen depletion was not a significant restricting factor in this environment. stratigraphic significance of foraminiferal assemblages age relationships the foraminiferal assemblages of the upper kapp toscana group are of low diversity, and the study of these faunas is still in a pioneering stage. in spite of these factors, the faunal content of the foraminiferal assemblages 1�3 reveals a significant stratigraphic potential as shown by the age distribution pattern of the various species in other regions. ammodiscus pseudoinfimus forma granulata is recorded from the pliensbachian of western siberia (azbel & grigalis 1991) and ammodiscus glumaceus ranges from toarcian to aalenian in western siberia and occurs in the toarcian of middle siberia (bulynnikova et al. 1990). bulbobaculites vermiculus is originally described from pliensbachian to toarcian strata from anholt, denmark (nagy & seidenkrantz 2003). lagenammina inanis occurs in pliensbachian to toarcian beds in western and middle siberia (bulynnikova et al. 1990) and reophax metensis ranges from upper sinemurian to lower bathonian with an acme in the pliensbachian and toarcian (nagy & johansen 1989). trochammina squamataformis is reported from the pliensbachian and toarcian of the caucasus and ukraine (azbel & grigalis 1991). verneuilinoides subvitreus was first described from the upper toarcian of the northern north sea basin but the closely related verneuilinoides mauritii (terquem) occurs in the pliensbachian (nagy & johansen 1991). the stratigraphical ranges mentioned above reveal the significant pliensbachian�toarcian affinities of the foraminiferal assemblages in this study. therefore, they are referred to these stages. of particular interest in this connection are the taxa a. pseudoinfimus forma granulata, b. vermiculus, l. inanis and t. squamataformis. for the beds above and below the mudstone levels, we follow the ages proposed by olaussen et al. (1984). a new reference section for the pliensbachian� toarcian biotic turnover? striking features of the analysed stø formation mudstone intervals are their transgressive nature and increased toc content, which are coupled with a pliensbachian�toarcian age (fig. 4). these relationships warrant a closer consideration of their possible connection to the global pliensbachian�toarcian turnover comprising several biotic extinction events. the main stages of the pliensbachian�toarcian turnover were a regression followed by a transgression leading to oceanic hypoxia (zakharov et al. 2006; wignall & bond 2008). the turnover with its main phase in the early toarcian falciferum zone affected primarily the marine realm expressed by a development and widespread extinction of invertebrates such as ammonites and bivalves. in northern siberia, the turnover comprises two major intervals with reduction of species diversities, the first in the antiquum zone and the second in the falciferum zone (zakharov et al. 2006). the stø formation mudstones and corresponding stratigraphic levels in the hammerfest basin can be s. hess et al. lower jurassic foraminifera citation: polar research 2014, 33, 20206, http://dx.doi.org/10.3402/polar.v33.20206 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20206 http://dx.doi.org/10.3402/polar.v33.20206 regarded as reference sections for the pliensbachian� toarcian turnover in the boreal seas. their foraminiferal assemblages might potentially define key horizons that could be used for basin-wide layer correlations and dating. however, prior to this additional research needs to be conducted to confirm the connection to the global pliensbachian�toarcian biotic turnover. conclusions lower jurassic foraminiferal assemblages from a marginal marine succession of the nordmela and stø formations cored in two commercial wells (7119/12-1 and 7119/12-2) in the hammerfest basin were analysed in order to contribute to the stratigraphy and to reconstruct palaeoenvironmental conditions. foraminiferal assemblages only occurred in samples from well 7119/12-1, where they are located in three mudstone intervals of the stø formation. the foraminiferal assemblages 1�3 contain exclusively agglutinated taxa and are characterized by low diversities (fisher ab5). these features and analogies to some modern faunas indicate restricted environmental conditions. the main restricting factor was low salinity in strongly delta-influenced waters. the foraminiferal assemblage 1 is developed at the base of the stø formation and represents transgressional conditions bringing strongly hyposaline lagoonal waters over freshwater strata. assemblages 2 and 3 occur in mudstone intervals higher in the stø formation and reveal increased diversities. they represent two major transgressions leading to extension of hyposaline waters with prodelta shelf mudstone deposition into more proximal hyposaline sandstone environments. the three foraminiferal assemblage compositions indicate a pliensbachian�toarcian age. the mudstones of the stø formation are considered as local developments of the global pliensbachian�toarcian transgressions and associated faunal change. in addition to the age relationships, this consideration is based on the highly transgressive nature of these mudstone horizons and their slightly increased toc content. acknowledgements this project, including a post-doctoral scholarship for sh, was supported by the statoil-funded research programme vista. the study is based on sample material obtained from statoil. we are particularly grateful to statoil for granting permission to publish the data presented here. the authors gratefully acknowledge the reviews by michael a. kaminski and an anonymous referee. references azbel a.j., & grigalis a.a. (eds.) 1991. praktičeskoe rukovodstvo po mikrofaune sssr. tom 5. foraminifery mezozoja. (practical guide to microfauna of the ussr. vol. 5. mesozoic foraminifera.) leningrad: all-union geological scientific research institute. bulynnikova s.p., komissarenko v.k., belousova n.a., bogomjakova e.d., ryl’kova g.e. & tylkina k.e. 1990. atlas molljuskov i foraminifer morskih otloženij verhnej jury i neokoma zapadno-sibirskoj neftegazonosnoj oblasti. tom 2, foraminifery. (atlas of molluscs and foraminifera from upper jurassic and neocomian marine deposits of the western siberian hydrocarbon region. vol. 2. foraminifera.) moscow: siberian scientific research institute of geology, geophysics and mineral resources. dalland a. worsley d. & ofstad k. (eds.) 1988. a lithostratigraphic scheme for the mesozoic and cenozoic succession offshore midand northern norway. npd-bulletin 4. stavanger: norwegian petroleum directorate. fisher r.a., corbet a.s. & williams c.b. 1943. the relation between the number of species and the number of individuals in a random sample of an animal population. journal of animal ecology 12, 42�58. loeblich a.r. & tappan h. 1988. foraminiferal genera and their classification. new york: van nostrand reinhold. løfaldi m. & nagy j. 1980. foraminiferal stratigraphy of jurassic deposits on kongsøya, svalbard. norsk polarinstitutt skrifter 172, 63�96. mørk a., dallmann w.k., dypvik h., johannessen e.p., larssen g.b., nagy j., nøttvedt a., olaussen s., pcelina t.m. & worsley d. 1999. mesozoic lithostratigraphy. in w.k. dallmann (ed.): lithostratigraphic lexicon of svalbard: review and recommendations for nomenclature use: upper palaeozoic to quaternary bedrock. pp. 127�214. tromsø: norwegian polar institute. murray j.w. 1973. distribution and ecology of living benthic foraminiferids. london: heinemann. murray j.w. 1991. ecology and palaeoecology of benthic foraminifera. harlow, uk: longman scientific & technical. nagy j. 1985a. jurassic foraminiferal facies in the statfjord area, northern north-sea. part 1. journal of petroleum geology 8, 273�295. nagy j. 1985b. jurassic foraminiferal facies in the statfjord area, northern north-sea. part 2. journal of petroleum geology 8, 389�403. nagy j. & basov v.a. 1998. revised foraminiferal taxa and biostratigraphy of bathonian to ryazanian deposits of spitsbergen. miropaleontology 44, 217�255. nagy j. & berge s.h. 2008. micropalaeontological evidence of brackish water conditions during deposition of the knorringfjellet formation, late triassic�early jurassic, spitsbergen. polar research 27, 413�427. nagy j., hess s. & alve e. 2010. environmental significance of foraminiferal assemblages dominated by small-sized ammodiscus and trochammina in triassic and jurassic strata. earth-science reviews 99, 31�49. lower jurassic foraminifera s. hess et al. 10 (page number not for citation purpose) citation: polar research 2014, 33, 20206, http://dx.doi.org/10.3402/polar.v33.20206 http://www.polarresearch.net/index.php/polar/article/view/20206 http://dx.doi.org/10.3402/polar.v33.20206 nagy j., hess s., dypvik h. & bjærke t. 2011. marine shelf to paralic biofacies of upper triassic to lower jurassic deposits in spitsbergen. palaeogeography, palaeoclimatology, palaeoecology 300, 138�151. nagy j. & johansen h.o. 1989. preservation and distribution pattern reophax metensis (foraminifera) in the jurassic of the north sea. journal of foraminiferal research 19, 337�348. nagy j. & johansen h.o. 1991. delta-influenced foraminiferal assemblages from the jurassic (toarcian�bajocian) of the northern north sea. micropaleontology 37, 1�40. nagy j. & seidenkrantz m.s. 2003. new foraminiferal taxa and revised biostratigraphy of jurassic marginal marine deposits on anholt, denmark. micropaleontology 49, 27�46. nikitenko b.l. & mickey m.b. 2004. foraminifera and ostracods across the pliensbachian�toarcian boundary in the arctic realm (stratigraphy, palaeobiogeography and biofacies). geological society special publication 230, 137�174. olaussen s., dalland a., gloppen t.g. & johannessen e. 1984. depositional environment and diagenesis of jurassic reservoir sandstones in the eastern part of troms i area. in a.m. spencer et al. (eds.): petroleum geology of the north european margin. pp. 61�79. london: graham and trotman. riis f., lundschien b.a., høy t. & mørk a. 2008. evolution of the triassic shelf in the northern barents sea region. polar research 27, 318�338. scott d., gradstein f. & schaffer c. 1983. the recent as a key to the past: does it apply to agglutinated foraminiferal assemblages? iku publication supplement 108, 147�157. shannon c.e. 1948. a mathematical theory of communication. bell system technical journal 27, 379�423, 623�656. souaya f.j. 1976. foraminifera of sun�gulf�global linckens island well p-46, arctic archipelago, canada. micropaleontology 22, 249�306. suan g., nikitenko b., rogov m.a., baudin f., spangenberg j.e., knyazev v.g., glinskikh l.a., goryacheva a.a., adatte t., riding j.b., foellmi k.b., pittet b., mattioli e. & lécuyer c. 2011. polar record of early jurassic massive carbon injection. earth and planetary science letters 312, 102�113. tappan h. 1955. foraminifera from the arctic slope of alaska. part 2. jurassic foraminifera. professional papers u.s. geological survey b 236, 21�90. van veen p.m., skjold l.j., kristensen s.e., rasmussen a., gjelberg j. & stølen t. 1992. triassic sequence stratigraphy in the barents sea. in t.o. vorren et al. (eds.): arctic geology and petroleum potential. pp. 363�375. amsterdam: elsevier. wall j.h. 1983. jurassic and cretaceous foraminiferal biostratigraphy in the eastern sverdrup basin, canadian arctic archipelago. bulletin of canadian petroleum geology 31, 246�281. wignall p.b. & bond d.p.g. 2008. the end-triassic and early jurassic mass extinction records in the british isles. proceedings of the geologists’ association 119, 73�84. zakharov v.a., shurygin b.n., il‘ina v.i. & nikitenko b.l. 2006. pliensbachian�toarcian biotic turnover in north siberia and the arctic region. stratigraphy and geological correlation 14, 399�417. s. hess et al. lower jurassic foraminifera citation: polar research 2014, 33, 20206, http://dx.doi.org/10.3402/polar.v33.20206 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20206 http://dx.doi.org/10.3402/polar.v33.20206 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <feff005500740069006c0069007a006500200065007300740061007300200063006f006e00660069006700750072006100e700f5006500730020007000610072006100200063007200690061007200200064006f00630075006d0065006e0074006f007300200050004400460020006500200065006d0069007400690072002000720065006c0061007400f300720069006f007300200073006f00620072006500200063006f006e0066006f0072006d0069006400610064006500200063006f006d0020006f0020005000440046002f0058002d0033002e0020005000440046002f0058002000e900200075006d0020007000610064007200e3006f002000640061002000490053004f00200070006100720061002000740072006f0063006100200064006500200063006f006e0074006500fa0064006f00200067007200e1006600690063006f002e002000500061007200610020006f00620074006500720020006d00610069007300200069006e0066006f0072006d006100e700f50065007300200073006f00620072006500200063006f006d006f00200063007200690061007200200064006f00630075006d0065006e0074006f0073002000500044004600200065006d00200063006f006e0066006f0072006d0069006400610064006500200063006f006d0020006f0020005000440046002f0058002d0033002c00200063006f006e00730075006c007400650020006f0020004700750069006100200064006f002000550073007500e100720069006f00200064006f0020004100630072006f006200610074002e0020004f007300200064006f00630075006d0065006e0074006f0073002000500044004600200070006f00640065006d0020007300650072002000610062006500720074006f007300200063006f006d0020006f0020004100630072006f006200610074002c002000520065006100640065007200200034002e00300020006500200070006f00730074006500720069006f0072002e> /dan <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> /nld <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> /esp <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> /suo <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> /ita <feff00550073006100720065002000710075006500730074006500200069006d0070006f007300740061007a0069006f006e00690020007000650072002000760065007200690066006900630061007200650020006c006100200063006f006e0066006f0072006d0069007400e0002000610020005000440046002f0058002d003300200065002000630072006500610072006500200064006f00630075006d0065006e00740069002000500044004600200073006f006c006f00200069006e0020006300610073006f00200064006900200063006f006e0066006f0072006d0069007400e0002e0020005000440046002f0058002d0033002000e800200075006e006f0020007300740061006e0064006100720064002000490053004f00200070006500720020006c006f0020007300630061006d00620069006f00200064006900200063006f006e00740065006e00750074006f0020006700720061006600690063006f002e002000500065007200200075006c0074006500720069006f0072006900200069006e0066006f0072006d0061007a0069006f006e0069002000730075006c006c006100200063007200650061007a0069006f006e006500200064006900200064006f00630075006d0065006e00740069002000500044004600200063006f006e0066006f0072006d0069002000610020005000440046002f0058002d0033002c00200063006f006e00730075006c00740061007200650020006c0061002000470075006900640061002000640065006c006c0027007500740065006e007400650020006400690020004100630072006f006200610074002e0020004900200064006f00630075006d0065006e00740069002000500044004600200070006f00730073006f006e006f0020006500730073006500720065002000610070006500720074006900200063006f006e0020004100630072006f00620061007400200065002000520065006100640065007200200034002e003000200065002000760065007200730069006f006e006900200073007500630063006500730073006900760065002e> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice doi:10.3402/polar.v35.24571 r e s e a r c h / r e v i e w a r t i c l e variation in summer nitrogen and phosphorus uptake among siberian headwater streams john d. schade,1 erin c. seybold,2 travis drake,3 seth spawn,4 william v. sobczak,5 karen e. frey,6 robert m. holmes 4 & nikita zimov 7 1 environmental studies department, st. olaf college, 1520 st. olaf avenue, northfield, mn 55057, usa 2 nicholas school of the environment, duke university, po box 90328, durham, nc 27708, usa 3 environmental studies program, university of colorado, 1201 17th street, boulder, co 80309, usa 4 wood hole research center, 149 woods hole road, falmouth, ma 02540, usa 5 biology department, college of the holy cross, 1 college street, worcester, ma 01610, usa 6 department of geography, clark university, 950 main street, worcester, ma 01610, usa 7 northeast science station, p.o. box 18, cherskiy, sakha republic, russia keywords arctic streams; nutrient uptake; hydrologic transient storage; phosphorus sorption; coupled n and p cycling. correspondence john d. schade, environmental studies department, st. olaf college, 1520 st, olaf avenue, northfield, mn 55057, usa. e-mail: schade@stolaf.edu abstract arctic streams are likely to receive increased inputs of dissolved nutrients and organic matter from thawing permafrost as climate warms. documenting how arctic streams process inorganic nutrients is necessary to understand mechanisms that regulate watershed fluxes of permafrost-derived materials to downstream ecosystems. we report on summer nitrogen (n) and phosphorus (p) uptake in streams draining upland soils from the pleistocene, and lowland floodplain soils from the holocene, in siberia’s kolyma river watershed. uptake of n and p differed between upland and floodplain streams, suggesting topographic variation in nutrient limitation. in floodplain streams, p uptake rate and uptake velocity were higher than n, while upland streams had similar values for all n and p uptake metrics. phosphorus uptake velocity and size of the transient hydrologic storage zone were negatively related across all study streams, indicating strong influence of hydrologic processes on nutrient fluxes. physical sorption of p was higher in floodplain stream sediments relative to upland stream sediments, suggesting more physically driven uptake in floodplain streams and higher biological activity in upland streams. overall, these results demonstrate that high-latitude headwater streams actively retain n and p during summer base flows; however, floodplain and upland streams varied substantially in n and p uptake and may respond differently to inorganic nutrient and organic matter inputs. our results highlight the need for a comprehensive assessment of n and p uptake and retention in arctic streams in order to fully understand the impact of permafrost-derived materials on ecosystem processes, and their fate in continental drainage networks. to access the supplementary material for this article, please see the supplementary files under article tools, online. in the coming century, anthropogenic climate warming is predicted to be amplified in the arctic relative to lower latitudes (symon et al. 2005). arctic amplification (serreze & francis 2006; screen & simmonds 2010) will likely lead to globally significant consequences, including the thawing of permafrost soils that underlay many arctic ecosystems (schuur et al. 2008; schaefer et al. 2011). these soils are generally rich in organic matter and represent a significant pool of labile carbon and other nutrients, which have been stored for thousands of years (zimov et al. 2006; tarnocai et al. 2009). this is particularly true in north-east siberia, where permafrost polar research 2016. # 2016 j.d. schade et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 24571, http://dx.doi.org/10.3402/polar.v35.24571 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/24571/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24571/0 http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/24571 http://dx.doi.org/10.3402/polar.v35.24571 soils are composed of frozen organic-rich loess deposits, which will release a significant amount of highly-labile carbon and nutrients upon thaw (vonk et al. 2013). small, first-order streams will receive these materials, owing to their unique position linking upland terrestrial environments to larger rivers and coastal oceans, and therefore have the potential to regulate the export of carbon, n and p to downstream ecosystems (alexander et al. 2000; wollheim et al. 2001). arctic streams have received insufficient attention to date, particularly in eastern siberia, and an improved understanding of their role in the landscape is essential to assessing the impact of permafrost thaw on nutrient export to the ocean. recent studies of arctic rivers have shown a consistent seasonal pattern in which concentration and bioavailability of organic matter and nutrients is high during spring thaw, followed by a substantial decline in the summer (holmes et al. 2008; mann et al. 2012), with most nutrient flux to the ocean occurring during spring snow melt (finlay et al. 2006; holmes et al. 2008; mann et al. 2012). these studies, however, have focused on temporal dynamics at the mouths of these rivers, and we still do not know where or how the signal observed at river mouths is generated within watersheds. one possible explanation is that organic matter and nutrient inputs from terrestrial ecosystems may be lower and more refractory in the summer as hydrologic connections between terrestrial ecosystems and headwater streams decrease, leading to observed low concentrations in summer. alternatively, low summer export of nutrients from large rivers may indicate a shift to active processing of nutrient inputs by small streams during summer months, when stream discharge decreases and temperatures rise. furthermore, during these months, small streams have high potential to alter nutrient fluxes because there is significant contact between water and the streambed where physical sorption by sediment particles or biological uptake by microbes may remove nutrients from the water column (alexander et al. 2000; sobczak & findlay 2002). biological and physical processes in small arctic streams, therefore, may be playing a larger role in regulating nutrient exports than is generally recognized. research on arctic streams has primarily focused on their metabolic response to n and p enrichment, with little attention explicitly paid to rates of n and p uptake. enrichment studies show a range of biological responses, including increased primary and secondary productivity and heterotrophic activity that suggest p limitation (peterson et al. 1985; slavik et al. 2004; mann et al. 2013). these observed increases in biological activity have been linked to changes in uptake rates of n and p in headwater streams that may influence the mass and form of nutrient exports. few published studies, however, report direct measurements of nutrient uptake rates for arctic streams, and these have been geographically limited to streams in alaska (wollheim et al. 2001; slavik et al. 2004; benstead et al. 2005; greenwald et al. 2008). comparable studies of streams in the siberian arctic are notably absent. our objective in this study was to investigate landscape variation in rates of n and p uptake, and the relative importance of physical and biological processes that may control nutrient uptake during the summer low-flow period in arctic streams in eastern siberia. we studied two classes of streams that varied in topographic position and sediment composition and age. all streams drain subwatersheds of the kolyma river that are underlain by continuous permafrost. upland streams drain pleistoceneaged loess soils, while floodplain streams drain holoceneaged soils. this comparison will provide information on differences in the relative importance of physical and biological processes relevant to developing hypotheses on how streams in this region may respond to changes in inputs as permafrost thaws. methods in this study, we applied a whole-ecosystem approach using nutrient spiralling models that explicitly integrate nutrient processing rates and downstream transport (newbold et al. 1981; newbold et al. 1983; newbold 1992). we also investigated the role of physical processes, including transient storage of water within the channel and physical sorption by sediments in regulating nutrient fluxes. nutrient spiralling provides a conceptual framework and a numerical ‘‘toolbox’’ that ecologists can use to compare the ability of streams to retain and process nutrients and provides a whole-system approach to investigate ecosystem responses to environmental change (webster & patten 1979; newbold et al. 1981; ensign & doyle 2006; mulholland et al. 2008; valett et al. 2008). in this work, we used these tools to assess spatial variation in nutrient processing in arctic streams and to investigate potential patterns in nutrient limitation across abbreviations in this article doc: dissolved organic carbon don: dissolved organic nitrogen n: nitrogen otis: one-dimensional transport with inflow and storage model p: phosphorus srp: soluble reactive phosphorous tsz: transient storage zone n and p cycling in arctic streams j.d. schade et al. 2 (page number not for citation purpose) citation: polar research 2016, 35, 24571, http://dx.doi.org/10.3402/polar.v35.24571 http://www.polarresearch.net/index.php/polar/article/view/24571 http://dx.doi.org/10.3402/polar.v35.24571 the landscape. nutrient spiralling is quantified in streams using related metrics (summarized in supplementary table s1) including uptake length (sw), uptake rate (u) and uptake velocity (or mass transfer coefficient, vf). uptake length is the average distance a nutrient atom travels in a stream before being removed from the water column. uptake rate represents the area-specific rate of nutrient loss from the water column and is commonly used to compare nutrient demand across streams with differing discharge. uptake velocity represents the demand for nutrients relative to concentration (stream solute workshop 1990), and allows comparison across streams that differ in discharge and background nutrient concentrations. we also used whole-stream solute additions to estimate transient storage, and chamber nutrient uptake experiments to investigate the relative importance of physical sorption and biological uptake in p removal from the water column. these experiments are described in greater detail below. study site study streams are located in the kolyma river basin, near the city of cherskiy in north-east siberia (fig. 1). the kolyma river basin is unique in that it is the largest watershed in the world underlain by continuous permafrost (zimov et al. 2006; frey & mcclelland 2009). the climate in this region is dry and continental. mean annual temperature (1999�2010) is �9.98c, but monthly mean temperatures reach 13.48c in july. annual precipitation is low, ranging from 200 to 215 mm yr �1 , with only 80�100 mm falling as rain during the summer months (corradi et al. 2005). nutrient spiralling experiments were conducted throughout july 2009 in five headwater streams (one experiment in each), selected based on landscape position and accessibility from the northeast science station. two (fps1, fps2) streams were located in the low-lying floodplain of the kolyma river, where sediments mainly originate from the holocene. three streams (dvy, tdo and y4) were located topographically higher in the landscape and drained yedoma soils, which date primarily from the pleistocene. all study streams were quite small (discharge of 1�3 l/s, stream order 1�2, table 1), with heavily vegetated banks and silty substrates. bank vegetation was similar between floodplain and upland streams and consisted mainly of sedge tussocks and small woody shrubs. whole-stream nutrient uptake to quantify nutrient uptake, we conducted whole-stream nutrient release experiments consisting of simultaneous additions of n (as nh4 � ) and p (as po4 3 � ) with a conservative tracer (cl � ) to each of the five study streams during summer base flow in july 2009. our decision to add n and p simultaneously was a consequence of fig. 1 map showing location of experimental streams within the kolyma river watershed in north-eastern siberia. john d. schade et al. n and p cycling in arctic streams citation: polar research 2016, 35, 24571, http://dx.doi.org/10.3402/polar.v35.24571 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/24571/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24571/0 http://www.polarresearch.net/index.php/polar/article/view/24571 http://dx.doi.org/10.3402/polar.v35.24571 logistical constraints that only allowed one visit to each stream during our field expedition, coupled with the need for information on both n and p uptake given uncertainties about nutrient limitation and the impact of future changes in nutrient input from thawing permafrost. we have acknowledged in our previous work (schade et al. 2011) that this decision has an impact on our interpretation of our results. solutes were dissolved in 30 l of stream water and were added to the surface stream at the top of each reach using a metering pump (fluid metering inc.) at a rate designed to increase nutrient concentrations. in all streams, nutrient enrichments were b60 mg l�1, compared to ca. 100 mg l�1 or less typical of previous studies (as reported by hoellein et al. 2007). solutes were added at a constant rate until concentrations reached a plateau at all downstream sampling points. conductivity was measured continuously using ysi 556 multimeters (ysi incorporated) at the top and bottom of each reach before, during and after solute releases to monitor changes in cl � for transient storage modelling and to identify when plateau concentrations were reached for nutrient sampling. in each reach, five transects were established every 10�15 m, depending on total reach length, which varied from 40 to 60 m. triplicate water samples were collected at each transect prior to the addition and once concentrations reached plateau. all water samples were filtered through whatman gf/f filters (0.7 mm) immediately upon return to the laboratory, and analysed for srp (an index of po4 3 � ) and ammonium (nh4 � ) concentrations at the northeast science station within 24 hours. subsamples were also frozen for return to st. olaf college for analysis of nitrate (no3 � ) concentration. ammonium concentrations were measured using a fluorometric method developed by holmes et al. (1999) and modified by taylor et al. (2007) on a turner designs aquafluor portable fluorometer. srp was measured using the molybdate colorimetric method on a biotek microplate spectrophotometer. nitrate was analysed using cadmium reduction on a lachat qc8000 autoanalyzer. background nutrient concentrations were subtracted from all plateau concentrations to calculate spiralling metrics. all methods had detection limits below 3 mg l�1. uptake lengths were estimated by regressing logtransformed, background-corrected nutrient concentrations at plateau at each transect against distance downstream (supplementary table s1). the inverse of the regression slope is equivalent to the uptake length. areal nutrient uptake rates and uptake velocity (supplementary table s1) were calculated using the equations below: u ¼ qc w � sw vf ¼ u c ; where u is areal uptake rate (mg m�2 s�1), vf is uptake velocity (m s �1 ), q is discharge (l s �1 ), c is background nutrient concentration (mg l�1), w is stream width (m) and sw is uptake length (m). transient storage modelling transient storage refers to the temporary retention of water and solutes and may occur in small eddies, in stagnant pools, or within the porous sediments below or lateral to the main channel, which together constitute what is referred to as the tsz. we require estimates of the size of the tsz and the degree of exchange between it and the main channel to properly understand the fate of solutes, including n and p, which depend on hydrologic residence time and biological activity of different stream zones (valett et al. 2008). to characterize hydrologic properties of our sample streams, we applied the otis model (runkel 1998), which has been used to characterize the fate of solutes in a wide range of rivers and streams (edwardson et al. 2003; salehin et al. 2003; ensign & doyle 2006; zarnetske et al. 2007). it comprises a set of mass balance equations for both the main channel, in which solute transport is governed by the advection� dispersion equation, and the tsz, where advection and table 1 mean background values for relevant physical and chemical variables for the five streams used in this study. yedoma floodplain dvy tdo y4 fps1 fps2 physical discharge (l s �1 ) 3.5 2 1.07 3.6 2.5 width (m) 0.52 0.45 0.47 1.02 0.95 depth (m) 0.08 0.04 0.06 0.09 0.07 velocity (m s �1) 0.01 0.01 0.03 0.02 0.03 order 1 1 2 1 1 do %sata 71.8 60.6 90.3 53.9 79.3 temp (c) 10.5 9.5 4.6 9.2 9.2 cond (ms m�1) 23 27 21 32 35 chemical doc (mg/l) 18 16.4 18.1 13 14 don (mg/l) 0.53 0.62 0.56 0.56 0.79 doc:don 39.6 36 37.7 27 20.7 nh4 (mg/l) 21 29 30 18 60 no3 (mg/l) 10 12 5 9 10 po4 (mg/l) 13.7 32.6 34.7 9.6 18.5 nh4:no3 2.1 2.4 6 2 6 molar in:ip 5 2.8 2.2 6.2 8.4 a percent saturation of dissolved oxygen. n and p cycling in arctic streams j.d. schade et al. 4 (page number not for citation purpose) citation: polar research 2016, 35, 24571, http://dx.doi.org/10.3402/polar.v35.24571 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24571/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24571/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24571/0 http://www.polarresearch.net/index.php/polar/article/view/24571 http://dx.doi.org/10.3402/polar.v35.24571 dispersion are disregarded because downstream transport from these zones is assumed to be negligible (runkel 1998). we used two metrics from otis to characterize transient storage in the five sample streams; the ratio of tsz area to main channel area (as/a) and mean storage residence time (tstor). the first metric, as/a, represents the relative size of the tsz. because as/a does not incorporate the rate of exchange between the two zones, it does not reflect how long a given molecule spends in the storage zone. the second metric, tstor, represents the average time that a water particle spends in storage and is calculated as: tstor ¼ 1 a � as a ; where a is the storage zone exchange coefficient, or the rate at which molecules move between the main channel and the tsz. thus, tstor incorporates both the size of the tsz relative to the main channel and the exchange rate between the two zones (zarnetske et al. 2007). physical sorption physical sorption of p in sediments from the five study streams was estimated following protocols outlined by lottig & stanley (2007). at each stream, five sediment samples were collected along a longitudinal transect at 1 m intervals. two samples were taken from the right side of the stream, two from the left, and one from the middle. samples were collected in plastic resealable bags that were kept sealed until bags were submerged in sediments to reduce potential contamination by surface water and aquatic vegetation. sediment samples were kept cool and out of direct sunlight until incubation. in addition, 10 l of water was collected from the top of the longitudinal transect for use in the incubation. sediment subsamples were pooled by stream and mixed thoroughly prior to incubations, which were conducted in triplicate for each stream, in 0.5 pint mason jars. into each jar, we mixed 30 g of sediment with 10 ml of site water. half the jars were treated with 2 ml of a 37% formalin solution and shaken continuously for 30 minutes to kill the biological component of the sediments. following this incubation, 100 ml of site water was added to killed and live jars. all jars (live and killed sediments) received a po4 3 � spike with a target concentration of 2 mg/l and were incubated for two hours and shaken every 15 minutes. initial and final nutrient samples were collected, filtered and analysed using the procedures described above. phosphorus uptake by killed sediments was used to estimate physical sorption, while the difference in p uptake between live and killed sediments was used to estimate uptake due to biological processes. statistical analysis all comparisons of means between upland and floodplain streams were conducted as two-sample student’s t-tests with three degrees of freedom, following tests for adherence to assumptions of normality and equal variances. because of low sample sizes, we report two levels of significance. we adhere to the convention of using an alpha of 0.05 to determine statistical significance, but we also acknowledge our lack of statistical power with use of the term ‘‘marginally significant’’ for results with p values that fall between 0.05 and 0.1. to assess differences in relationships between tsz metrics, stream discharge, and nutrient uptake metrics, we used linear regression analysis. results background water chemistry most physical and chemical characteristics were similar between upland and floodplain streams (table 1). the exceptions were significantly higher mean concentrations of doc (17.590.6 vs. 13.590.5 mg l �1 ; p �0.02) and doc:don (37.891.04 vs. 23.993.2; p �0.001), in upland streams, slightly higher in:ip [(nh4�no3)/srp] in floodplain streams, which was marginally significant (7.391.1 vs. 3.390.9; p �0.06), and higher srp in yedoma streams, although this difference was not statistically significant (2796.7 vs. 1494.5 mg l�1; p �0.22). in all streams, don was the most abundant form of n, with concentrations an order of magnitude higher than either nh4 or no3. inorganic n pools were dominated by nh4 (nh4:no3�2), and no3 concentrations were generally quite low (table 1). concentrations of srp were more variable between streams, ranging from ca. 9 to 35 mg l�1, and n:p of the inorganic pool (in:ip; table 1) was generally low in all streams (56.2). whole-stream nutrient uptake mean uptake lengths of n (swn) were much longer in floodplain streams than upland streams (455 and 81 m, respectively; p �0.006; fig. 2a), while uptake lengths of p were similar (31 and 52 m, respectively; p�0.43; fig. 2a). as a result, swn:swp was much higher in floodplain john d. schade et al. n and p cycling in arctic streams citation: polar research 2016, 35, 24571, http://dx.doi.org/10.3402/polar.v35.24571 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24571 http://dx.doi.org/10.3402/polar.v35.24571 streams than upland streams (15 and 1.6, respectively; p �0.005; fig. 2d). results from both u and vf showed a similar pattern to uptake lengths, although the differences were not statistically significant (fig. 2b, c). in addition, no3 concentrations did not increase significantly during any nh4 additions, suggesting nitrification rates were too low to explain longitudinal declines in nh4 concentrations in all streams. the ratios of un:up and vfn:vfp were higher in upland streams than floodplain streams, although these differences were only marginally significant (pb0.1; fig. 2e, f). within upland streams, statistical comparisons between spiralling metrics for n and p yielded no significant differences. in the floodplain streams, however, p uptake lengths were significantly lower than n uptake lengths (p �0.003, fig. 2a), and up was significantly higher than un (p � 0.01, fig. 2b), while vfp was higher than vfn but this difference was only marginally significant (pb0.1, fig. 2c). additionally, no spiralling metrics for either n or p were significantly related to discharge in either upland or floodplain streams. transient storage modelling we found no significant differences when comparing means between upland and floodplain streams for either as/a or tstor; therefore, we used a regression approach to assess patterns in transient storage. both as/a (r 2 �0.925, p�0.025) and tstor (r 2 �0.793, p �0.027) showed a strong negative relationship with discharge (q) across all streams (fig. 3a, b). we also found negative relationships between vfp and both as/a and tstor, although these relationships were not statistically significant (fig. 3c, d). it should be noted that as and tstor could not be accurately modelled for stream fps2 because of an instrument malfunction during solute addition. this malfunction did not affect our ability to assess nutrient spiralling metrics. p sorption in all sorption experiments, a high proportion (ca. 60� 80%) of added p was removed during incubation. upland sediments showed a significantly higher proportion of fig. 2 nutrient spiralling parameters (sw, u, vf) for (a�c) n and p and (d�f) their ratios in upland and floodplain streams. error bars are 91 standard error. n and p cycling in arctic streams j.d. schade et al. 6 (page number not for citation purpose) citation: polar research 2016, 35, 24571, http://dx.doi.org/10.3402/polar.v35.24571 http://www.polarresearch.net/index.php/polar/article/view/24571 http://dx.doi.org/10.3402/polar.v35.24571 biological uptake than floodplain sediments (18% vs. 7% respectively; pb0.05; fig. 4). physical sorption, however, was responsible for a higher proportion of p removal than biological uptake in all sediment experiments. discussion nutrient spiralling metrics our results clearly show that small streams in the kolyma river basin have the potential to act as active processors of nutrients during summer months, but that there is significant landscape-scale variation in nutrient demand, which elements are being processed, and the relative importance of biological uptake. specifically, our results highlight fundamental differences in how upland and floodplain streams process n and p inputs. n and p uptake lengths in upland streams were similar, while floodplain streams were characterized by relatively high p uptake and negligible n uptake (fig. 2). one hypothesis for this observation is simply p limitation of floodplain streams, as has been observed in the alaskan tundra (peterson et al. 1985; slavik et al. 2004). alternatively, this pattern may be the result of high physical sorption of p (lottig & stanley 2007) and low biological uptake of nutrients in floodplain streams relative to upland streams. results of sorption experiments support this conclusion, suggesting that biological uptake of p in upland streams is threefold higher than in floodplain streams and that nearly all p uptake in floodplain streams was explained by physical processes (ca. 95%, fig. 4). in addition, we suggest that physical processes dominate p uptake, while nh4 uptake is likely to be a mix of physical and biological factors. differences in concentration and chemical composition of dissolved organic matter may contribute to variation in fig. 3 relationships between transient storage indices (as/a and tstor) and (a, b) discharge and (c, d) vfp. error bars are 91 standard error. fig. 4 biological uptake of p by floodplain and upland sediments. error bars are 91 standard error. john d. schade et al. n and p cycling in arctic streams citation: polar research 2016, 35, 24571, http://dx.doi.org/10.3402/polar.v35.24571 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24571 http://dx.doi.org/10.3402/polar.v35.24571 n uptake between upland and floodplain streams. all study streams were undersaturated with dissolved oxygen and showed high nh4:no3, suggesting heterotrophic activity is likely to dominate stream metabolism. concentrations of doc are relatively high in all study streams (ca. 13�18 mg l�1, table 1) and could contribute substantially to heterotrophic metabolism, depending on its quality (mann et al. 2012). upland streams are roughly 30% higher in background doc, and previous work has shown doc in upland streams to be more labile (mann et al. 2013). in addition, upland streams are ca. 35% higher in doc:don, and ca. 55% lower in in:ip (table 1) than floodplain streams. we suggest that these factors combined may contribute to higher nh4 demand in upland streams, but this remains quite speculative to date and should be viewed with caution. in contrast to n uptake, p uptake did not differ between upland and floodplain streams, and, as discussed above, is likely explained by physical sorption. overall, our results suggest that sediment characteristics that influence p sorption and hydrologic variables that influence how water and sediments interact are likely to be important for understanding how streams will process materials entering from the surrounding watershed. indeed the relationship between transient storage and p uptake (see below) highlights the importance of understanding hydrologic exchange between surface and sediments (see also greenwald et al. 2008). transient storage and nutrient uptake transient storage dynamics of siberian arctic streams are comparable to those in streams in other regions. the average as/a for our study streams was ca. 0.24, similar to a range of 0.2�0.6 reported for temperate streams (d’angelo et al. 1993; harvey et al. 2003), and to values of 0.31 and 0.32 reported for similar small arctic streams in alaska (edwardson et al. 2003, zarnetske et al. 2007). we also found an inverse relationship between transient storage (tstor, as/a) and discharge (q), consistent with previous studies (d’angelo et al. 1993; edwardson et al. 2003; zarnetske et al. 2008) that suggest that frozen active layer soils and, in some cases, shallow permafrost can act as barriers to deeper hyporheic exchange with groundwater aquifers. this may result in increased flushing of surface features when discharge increases, particularly during early spring and summer thaw, which may reduce hydrologic residence time in tszs. our results also suggest that transient storage is affecting p processing rates (fig. 3c, d). although uncommon, our observation of a negative relationship between both tstor and as/a and vfp is consistent with other work that found the tsz to be less active in terms of nutrient uptake relative to the main channel (valett et al. 2002), although the explanation for these results remains unclear. our data are not extensive enough to contribute substantially to a mechanistic understanding of this pattern, and more data are required to confirm the generality of our result. a better, more mechanistic, understanding of the drivers of nutrient dynamics in streams of this region represents a priority for future research. implications the consequences of increased input of nutrients from permafrost thaw for aquatic food webs and nutrient transport are likely to be quite different for floodplain versus upland streams, particularly if physical processes, rather than biological uptake, dominate nutrient loss from the water column to a greater degree in the floodplain. it seems quite likely that increasing organic matter and nutrient inputs will stimulate biological activity to a greater degree than physical processes (lottig & stanley 2007), which may lead to larger changes in organic matter and nutrient dynamics in upland streams. this may result in very different spatial and temporal patterns in nutrient export downstream. indeed, our results suggest strong differences in the ratio of n uptake to p uptake between upland and floodplain streams that are likely the result of differences in the relative importance of biological and physical processes (fig. 2d�f). these data provide a preliminary understanding of n and p uptake in stream ecosystems in the siberian arctic. while these findings are only a snapshot of how these streams function in a highly seasonal and variable environment, they represent a first look at these processes during low-flow summer months when streams are the most active and their influence on downstream nutrient fluxes is likely to be near its maximum. multi-year data sets that measure these processes over multiple seasons and flow conditions are necessary to fully understand n and p cycling. despite the limited data set reported here, we have provided a substantial first step towards understanding stream biogeochemistry in an understudied yet critically important region of the world. acknowledgements this research was funded by the polaris project (arc1044612), and we are grateful to all polaris project participants for stimulating discussion and help with field and laboratory activities. we especially thank greg fiske at the woods hole research center for the map in fig. 1. we are also grateful to three anonymous reviewers for n and p cycling in arctic streams j.d. schade et al. 8 (page number not for citation purpose) citation: polar research 2016, 35, 24571, http://dx.doi.org/10.3402/polar.v35.24571 http://www.polarresearch.net/index.php/polar/article/view/24571 http://dx.doi.org/10.3402/polar.v35.24571 insightful comments that substantially improved the quality of the manuscript. references alexander r.b., smith r.a. & schwarz g.e. 2000. effects of stream channel size on the delivery of nitrogen to the gulf of mexico. nature 403, 758�761. benstead j.p., deegan l.a., peterson b.j., huryn a.d., bowden w.b., suberkropp k., buzby k.m., green a.c. & vacca j. 2005. responses of a beaded arctic stream to shortterm n and p fertilization. freshwater biology 50, 277�290. corradi c., kolle o., walter k., zimov s.a. & schulze e.d. 2005. carbon dioxide and methane exchange of a northeast siberian tussock tundra. global change biology 11, 1910�1925. d’angelo d., webster j., gregory s. & meyer j. 1993. transient storage in appalachian and cascade mountain streams as related to hydraulic characteristics. journal of the north american benthological society 12, 223�235. edwardson k.j., bowden w.b., dahm c. & morrice j. 2003. the hydraulic characteristics and geochemistry of hyporheic and parafluvial zones in arctic tundra streams, north slope, alaska. advances in water resources 26, 907�923. ensign s.h. & doyle m.w. 2006. nutrient spiraling in streams and river networks. journal of geophysical research* biogeosciences 111, g04009, doi: http://dx.doi.org/10.1029/ 2005jg000114 finlay j., neff j., zimov s., davydova a. & davydov s. 2006. snowmelt dominance of dissolved organic carbon in high-latitude watersheds: implications for characterization and flux of river doc. geophysical research letters 33, l10401, doi: http://dx.doi.org/10.1029/2006gl025754 frey k.e. & mcclelland j.w. 2009. impacts of permafrost degradation on arctic river biogeochemistry. hydrological processes 23, 169�182. greenwald m.j., bowden w.b., gooseff m.n., zarnetske j.p., mcnamara j.p., bradford j.h. & brosten t.r. 2008. hyporheic exchange and water chemistry of two arctic tundra streams of contrasting geomorphology. journal of geophysical research*biogeosciences 113, g02029, doi: http:// dx.doi.org/10.1029/2007jg000549 harvey j., conklin m. & koelsch r. 2003. predicting changes in hydrologic retention in an evolving semi-arid alluvial stream. advances in water resources 26, 939�950. hoellein t.j., tank j.l., rosi-marshall e.j., entrekin s.a. & lamberti g.a. 2007. controls on spatial and temporal variation of nutrient uptake in three michigan headwater streams. limnology and oceanography 52, 1964�1977. holmes r.m., mcclelland j.w., raymond p.a., frazer b.b., peterson b.j. & stieglitz m. 2008. lability of doc transported by alaskan rivers to the arctic ocean. geophysical research letters 35, l03402, doi: http://dx.doi.org/10.10289/ 2007gl032837 holmes r.m., minot a., kérouel r., hooker b.a. & peterson b.j. 1999. a simple and precise method for measuring ammonium in marine and freshwater ecosystems. canadian journal of fisheries and aquatic science 56, 1801�1808. lottig n.r. & stanley e.h. 2007. benthic sediment influence on dissolved phosphorus concentrations in a headwater stream. biogeochemistry 84, 297�309. mann p.j., davidova a., zimov n., spencer r.g.m., davydov s., bulygina e., zimov s. & holmes r.m. 2012. controls on the composition and liability of dissolved organic matter in siberia’s kolyma river basin. journal of geophysical research*biogeosciences 117, g01028, doi: http://dx.doi.org/ 10.1029/2011jg001798 mann p.j., sobczak w., larue m., bulygina e., davydova a., vonk j.e., schade j., davydov s., zimov n., holmes r.m. & spencer r.g.m. 2013. evidence for key enzymatic controls on metabolism of arctic river organic matter. global change biology 20, 1089�1100. mulholland p.j., helton a.m., poole g.c., hall r.o., hamilton s.k., peterson b.j. & tank j.l. 2008. stream denitrification across biomes and its response to anthropogenic nitrate loading. nature 452, 202�205. newbold j.d. 1992. cycles and spirals of nutrients. in p. calow & g.e. petts (eds.): the rivers handbook. pp. 370�408. oxford: blackwell scientific. newbold j.d., elwood j.w., o’neill r.v. & sheldon a.l. 1983. phosphorus dynamics in a woodland stream ecosystem: a study of nutrient spiraling. ecology 64, 1249�1265. newbold j.d., elwood j.w., o’neill r.v. & van winkle w. 1981. measuring nutrient spiraling in streams. canadian journal of fisheries and aquatic sciences 38, 860�863. peterson b.j., hobbie j.e., hershey a., lock m., ford t., vestal r., hullar m., ventullo r. & volk g. 1985. transformation of a tundra river from heterotrophy to autotrophy by addition of phosphorus. science 229, 1383�1386. runkel r.l. 1998. one dimensional transport with inflow and storage (otis): a solute transport model for streams and rivers. water-resources investigation report 98-4018. denver: us geological survey. salehin m., packman a.i. & worman a. 2003. comparison of hyporheic exchange in vegetated and unvegetated reaches of a small agricultural stream in sweden: seasonal variation and anthropogenic manipulation. advanced water resources 26, 951�964. schade j.d., macneill k., thomas s.a., mcneely f.c., welter j.r., hood j., goodrich m., power m.e. & finlay j.c. 2011. the stoichiometry of nitrogen and phosphorus spiraling in heterotrophic and autotrophic streams. freshwater biology 56, 424�436. schaefer k., zhang t., bruhwiler l. & barrett a.p. 2011. amount and timing of permafrost carbon release in response to climate warming. tellus series b 63, 165�180. schuur e.a.g., bockheim j., canadell j.g., euskirchen e., field c.b., goryachkin s.v., hagemann s., kuhry p., lafleur p.m., lee h., mazhitova g., nelson f.e., rinke a., romanovsky v.e., shiklomanov n., tarnocai c., venevsky s., vogel j.g. & zimov s.a. 2008. vulnerability of permafrost carbon to climate change: implications for the global carbon cycle. bioscience 58, 701�714. john d. schade et al. n and p cycling in arctic streams citation: polar research 2016, 35, 24571, http://dx.doi.org/10.3402/polar.v35.24571 9 (page number not for citation purpose) http://dx.doi.org/10.1029/2005jg000114 http://dx.doi.org/10.1029/2005jg000114 http://dx.doi.org/10.1029/2006gl025754 http://dx.doi.org/10.1029/2007jg000549 http://dx.doi.org/10.1029/2007jg000549 http://dx.doi.org/10.10289/2007gl032837 http://dx.doi.org/10.10289/2007gl032837 http://dx.doi.org/10.1029/2011jg001798 http://dx.doi.org/10.1029/2011jg001798 http://www.polarresearch.net/index.php/polar/article/view/24571 http://dx.doi.org/10.3402/polar.v35.24571 screen j.a. & simmonds i. 2010. the central role of diminishing sea ice in recent arctic temperature amplification. nature 464, 1334�1337. serreze m.c. & francis j.a. 2006. the arctic on the fast track of change. weather 61, 65�69. slavik k., peterson b.j., deegan l.a., bowden w.b., hershey a.e. & hobbie j.e. 2004. long-term responses of the kuparuk river ecosystem to phosphorus fertilization. ecology 85, 939�954. sobczak w.v. & findlay s. 2002. variation in bioavailability of dissolved organic carbon among stream hyporheic flowpaths. ecology 83, 3194�3209. stream solute workshop 1990. concepts and methods for assessing solute dynamics in stream ecosystems. journal of the north american benthological society 9, 95�119. symon c., arris l. & heal b. (eds.): 2005. arctic climate impact assessment. cambridge: cambridge university press. tarnocai c., canadell j.g., schuur e.a.g., kuhry p., mazhitova g. & zimov s. 2009. soil organic carbon pools in the northern circumpolar permafrost region. global biogeochemical cycles 23, gb2023, doi: http://dx.doi.org/10.1029/2008 gb003327 taylor b.w., keep c.a., flecker a.s., hall r.o., jr., koch b.j., tronstad l.m. & ulseth a.j. 2007. improving the fluorometric ammonium method: matrix effects, background fluorescence, and standard additions. journal of the north american benthological society 26, 167�177. valett h., crenshaw c. & wagner p. 2002. stream nutrient uptake, forest succession, and biogeochemical theory. ecology 83, 2888�2901. valett h.m., thomas s.a., mulholland p.j., webster j.r., dahm c.n., fellows c.s., crenshaw c.l. & peterson c.g. 2008. endogenous and exogenous control of ecosystem function: n cycling in headwater streams. ecology 89, 3515�3527. vonk j.e., mann p.j., davydov s., davydova a., spencer r.g.m., schade j.d., sobczak w.v., zimov n., zimov s.a., bulygina e., eglinton t.i. & holmes r.m. 2013. high biolability of ancient permafrost carbon upon thaw. geophysical research letters 40, 2689�2693. webster j.r. & patten b.c. 1979. effects of watershed perturbation on stream potassium and calcium dynamics. ecological monographs 49, 51�72. wollheim w.m., peterson b.j., deegan l.a., hobbie j.e., hooker b., bowden w.b., edwardson k.j., arscott d.b. & hershey a.e. 2001. influence of stream size on ammonium and suspended particulate nitrogen processing. limnology and oceanography 46, 1�13. zarnetske j.p., gooseff m.n., bowden w.b., greenwald m.j. & brosten t.r. 2008. influence of morphology and permafrost dynamics on hyporheic exchange in arctic headwater streams under warming climate conditions. geophysical research letters 35, l02501, doi: http://dx.doi.org/10.1029/ 2007gl032049 zarnetske j.p., gooseff m.n., brosten t.r., bradford j.h., mcnamara j.p. & bowden w.b. 2007. transient storage as a function of geomorphology, discharge, and permafrost active layer conditions in arctic tundra streams. water resources research 43, w07410, doi: http://dx.doi.org/10. 1029/2005wr004816 zimov s.a., schuur e.a.g. & chapin f.s. iii 2006. climate change: permafrost and the global carbon budget. science 312, 1612�1613. n and p cycling in arctic streams j.d. schade et al. 10 (page number not for citation purpose) citation: polar research 2016, 35, 24571, http://dx.doi.org/10.3402/polar.v35.24571 http://dx.doi.org/10.1029/2008gb003327 http://dx.doi.org/10.1029/2008gb003327 http://dx.doi.org/10.1029/2007gl032049 http://dx.doi.org/10.1029/2007gl032049 http://dx.doi.org/10.1029/2005wr004816 http://dx.doi.org/10.1029/2005wr004816 http://www.polarresearch.net/index.php/polar/article/view/24571 http://dx.doi.org/10.3402/polar.v35.24571 an upper proterozoic unconformity in northern wedel jarlsberg land, southwest spitsbergen: lithostratigraphy and tectonic implications m . bjornerud bjornerud, m . 1990: a n upper proterozoic unconformity in northern wedel jarlsberg land, southwest spitsbergen: lithostratigraphy and tectonic implications. polar resenrch 8 , 127-139. recent field studies of upper proterozoic rocks in northern wcdel jarlshcrg land, southwest spitshergen. have shed new light on thc prc-caledonian evolution of the region. a regional angular unconformity divides the greenschist-facies metasedimentary rocks into two distinct tectono-slratigraphic sequenees. thc sub-unconformity (nordbukta) sequence, exposed in the southwestern part of the study area, con5ists mainly of quartzites, phyllitcs and dolomites, and may be correlative with proterozoic rocks exposed ca\t of recherchebreen (magnethegda scqucnce) and south of torellbreeii (deikggd scqucncc). the nordhukta sequence was affected by l a r g e ~ l e recumbent folding during late (?) proterozoic tectonism. strata above the unconformity (dundcrbukta-recherchefjorden sequence) include conglomerates, dolomites. green and black phyllites, meta-basalts and vendian (?) diamictites, with laterally complex dcpiisitional relationships. the continuation of this sequence south of torellbreen is the sofiebogen group in the hornsund arca. the apparent continuity of both suband supra-unconformity proterozoic rocks across rcchcrchehreen and torellbreen is not compatiblc with the hypothesis that a major late dcvonian strikc slip terranc boundary lies beneath these glaciers. m . bj@merud, geology depnrtment, miami unioersity, oxford. ohio 45056, u . s . a . ; mu.y 1990 (reoiserf august 1990). the proterozoic succession exposed in northern wedel jarlsberg land, between bellsund and torellbreen, southwest spitsbergen (fig. l ) , consists of greenschist-facies metasedimentary and metavolcanic rocks, including quartzite, phyllite, conglomerate, dolomite, metabasalt, metatuff and diamictite. the total thickness of the succession may be as great as 9,000m ( b j ~ r n e r u d 1987). the age of these rocks is poorly constrained but considered to be upper proterozoic on the assumption that diamictites at the top of the succession are vendian glaciogenic deposits (harland 1964; hjelle 1969). until recently, the proterozoic succession had been studied only on a reconnaissance basis (orvin 1940; winsnes 1965; hjelle 1969; flood et al. 1971). considerable debate has centered on the nature of several clast-bearing units within the succession: congiomerates exposed at konglomeratfjellet, orvinfjellet and south of dunderdalen (orvin 1940; winsnes 1965; hjelle 1969) and the ‘kapp lyell’ diamictite sequence exposed between dunderdalen and chamberlin dalen (garwood & gregory 1898; hjelle 1969; harland 1978a; waddams 1983; kowallis & craddock 1984). resolving the depositional environment and lithostratigraphic position of these units is important for correlations not only with coeval rocks in svalbard but also with vendian and riphean successions throughout the north atlantic region. this has not been possible without careful and complete mapping, due to the depositional complexity of the proterozoic rocks and to the effects of polyphase caledonian deformation. (although tertiary tectonism also affected this area, k-ar age dates and structural relationships indicate that metamorphism and penetrative deformation of the proterozoic rocks were pre-tertiary.) most of northern wedel jarlsberg land (wjl) has now been mapped at a scale of 1 : 10,000 as part of a university of wisconsin (u.s.a.) project whose principal objective was to define caledonian structural features. a by-product of this work is detailed knowledge of the proterozoic lithostratigraphy and geologic setting of the region. this new information is of particular importance because the proterozoic rocks in northern wjl occur on both sides of a postulated caledonian strike-slip terrane boundary to which hundreds of kilometers 128 m. bjgrnerud barenb sea d caledonian ell sequence wendion?) dunderbukto-recherchefjocden sequence dunderdalen formation sletttjelldalen formation konglomerotfjellet formation ulor unconformity eotnedalen through dsrdolen formations mognefhsgda sequence peder kokk fjellet formalion kopp berg. evofj formations fig. 1. simplified geologic map and cross-section of northern wedcl jarlberg land. structure of nordbukta and magncth@gda sequences is too complex t o depict in detail at this scale (scc dallmann ct al. 1990). inset shows location within svalhard. upper proterozoic unconformity in northern wedel jarlsberg land 129 of late devonian displacement have been attributed (fig. 1) (harland 1978b; harland et al. 1985). upper proterozoic unconformity the purpose of this report is to describe a well exposed angular unconformity which divides the proterozoic succession of northern wjl into two stratigraphically and structurally distinct sequences (hauser et al. 1983; cochrane 1984; bjornerud 1985; kalinec 1985). the sub unconformity rocks, referred to here as the nordbukta sequence (nomenclature of dallmann et al. 1990), record a period of intense deformation in proterozoic time ( b j ~ r n e r u d 1987; bj0rnerud et al. 1990). the age of this event is constrained only to the extent that the supra-unconformity rocks, which include the vendian (?) diamictites, bear no evidence of pre-caledonian deformation. the laterally variable supra-unconformity sequence is divisible into two interlocking geographic parts, here designated the dunder bukta and recherchefjorden sequences (dall rnann et al. 1990). south of dunderdalen the contact between the nordbukta and dunderbukta sequences dips moderately to steeply northeastward as part of a regional caledonian-age fold (fig. 1). the discontinuity cuts across an estimated 1,500 m of nordbukta stratigraphy but is parallel to bedding in the dunderbukta sequence. the surface itself is well exposed along a 15 km nw-trending trace and it is clearly an angular unconformity rather than a fault. features which record erosion and deep weathering are common in rocks just below the unconforrnity. where the unconforrnity transects quartzitic units in the nordbukta sequence, for example, it is typically not a distinct surface but instead a zone of transition from regolith-like, fragmented and iron-stained quartz ite upward into quartzite-cobble conglomerates with graded bedding (nania 1987). nordbukta sequence carbonate rocks near the trace of the unconformity, moreover, contain sparry solution cavities and apparent collapse breccias which may represent palaeo-karst features formed at the same time as the unconformity (kalinec 1985). the rocks immediately above the unconformity are also characteristic of an erosional stratigraphic contact. the dunderbukta sequence begins with a basal conglomerate, containing rounded clasts of nordbukta rock types locally truncated by the unconformity. the mineralogy of the conglomerate matrix is generally different from that of the clasts, providing further evidence that the conglomerate is not a fault breccia. in addition, many clasts show deforrnational fabrics not present in the matrix, indicating that the fabrics formed before the clasts were incorporated into the conglomerate. although the clasts of the basal dunderbukta beds vary laterally from pebbleto boulder-size, the conglomerate shows an overall upward-fining trend. the transection of the nordbukta sequence by the unconformity indicates that the erosional surface developed on a strongly deformed terrane. contrasting structural styles in the two proterozoic sequences also point to a deformational episode which preceded deposition of the dunderbukta sequence. the nordbukta sequence is charac terized by a penetrative linear fabric not developed in the younger rocks. cross-bedding and graded bedding in nordbukta rocks show, moreover, that the sub-unconformity rocks were regionally overturned at the time the dunderbukta sequence was deposited. these and other structural features (recumbent isoclinal folds, sheath folds and zones of intense layer-parallel mylonitization) suggest that the nordbukta sequence was deformed during a proterozoic tectonic event, which involved development of a nappe-like fold whose upper limb was largely removed by erosion before n w *a -t." d y c fig. 2. schematic portrayal of late proterozoic events in northern wedel jarlsberg land. ornamentation as in fig. 1 . a. deposition of nordbukta sequence. b. late proterozoic tectonism involving nappe emplacement. zig-zag line shows level of future unconformity. c . erosion of upper limb of nappe structure, leaving lower limb with inverted stratigraphy. deposition of dunderdalen recherchefjorden sequence. 130 m . bjmrnerud the dunderbukta sequence was laid down (fig. 2) (bjornerud et al. 1990). regional structures and distribution of the two proterozoic sequences the large-scale distribution of proterozoic rocks in northern wjl is controlled by macroscopic nw-trending folds of caledonian age (flood et al. 1971; b j ~ r n e r u d 1987). south of dunderdalen the unconformity lies on the northeastern limb of an anticlinorium and dips almost homoclinally to the northeast, although its trace is offset about 6 kin in a dextral sense along the nne-trending orvindalen fault (fig. 1). nordbukta sequence rocks are exposed southwest of the unconformity trace, in the core of the anticlinorium, while dunderbukta sequence rocks lie on the ne dipping limb of the antiform and in the succeeding synclinorium, which is cored by the kapp lyell diamictites. in the eastern part of the study area (fig. 1) the northeastern limb of this synclinorium is partly obscured by the glacier recherchebreen, with a possible continuation of the proterozoic unconformity on this sw-dipping limb, beneath the glacier. this inference is supported by the fact that the lowest stratigraphic units of the recherchefjorden sequence occur immediately west of recherchebreen (mccord 1978; hauser 1982). the proterozoic magnethogda sequence (formerly ‘antoniabreen succession’; hauser 1982; craddock et al. 1985) is exposed in a broad antiformal arch east of recherchebreen. the magneth~gda sequence is the possible con tinuation of the sub-unconformity nordbukta sequence south of dunderdalen; evidence for and implications of this correlation are discussed below. sub-unconforrnity nordbukta sequence lithostratigraphy because the rocks of the nordbukta sequence have experienced at least two periods of penetrative deformation (proterozoic and cale donian), it is impractical to subdivide them according to stratigraphic rules developed for undeformed rocks. the lithostratigraphic div isions presented in this paper, therefore, are necessarily informal. table 1 summarizes the lithostratigraphy of the nordbukta sequence south of dunderdalen. (formation names pro posed here are the same as those which appear in the norsk polarinstitutt 1 : 100,000 geologic map of van keulenfjorden (dallmann et al. as mentioned, younging-direction indicators including cross-bedding and graded-bedding show that nordbukta strata are overturned on a regional scale (bjornerud 1985; kalinec 1985). these ‘way up’ indicators also show that progressively younger nordbukta rocks are preserved along the trace of the unconformity from peder kokkfjellet northwestward to floyfjellet (figs. 1 , 2 ) . the rocks of the nordbukta sequence fall into two broad divisions which suggest a general upward-shallowing trend. the upper division (peder kokkfjellet formation through dordalen formation; table 1) is characterized by an abundance of dolomites and limestones, while the lower division (evafjellet and kapp berg formations) consists of quartzites and phyllites. the lower division occurs mainly as shattered outcrops on the strandflat, and it lacks distinctive marker beds for regional correlation. massive white, pink and green quartzites, locally cross bedded, alternate with beds of black phyllite across the width of the strandflat from olafsonbukta to kapp borthen (fig. 1) (cheng 1984; cochrane 1984; wills 1984; kalinec 1985; phillips 1986). it is not clear whether the widely scattered occurrence of these quartzites represents strati graphic or tectonic repetition (perhaps both). the kapp berg formation has a greater proportion of phyllitic strata than the overlying evafjellet formation, but the boundary between the two units is not sharply defined. the bottom of the kapp berg formation is not exposed. the intercalation of quartzite and phyllite in the two formations suggests that they may represent shelf edge density-flow deposits, with the evafjellet formation more proximal to the sediment source than the kapp berg formation. however, tectonic obliteration of sedimentary structures makes it difficult to establish the depositional setting of the rocks. good exposures and the presence of several marker horizons allow the lithostratigraphy of the upper nordbukta division to be resolved in detail ( b j ~ r n e r u d 1985; bray 1985; kalinec 1985). the estimated total thickness of the upper division 1990).) upper proterozoic unconformity in northern wedel jarlsberg land 131 table i. lithostratigraphy of the sub-unconformity proterozoic sequences, northern wedel jarlsberg land. sw spitsbergen. unit estirnatcd nord b ukta sequence fl@yfjeller ro peder kokkfjeller (bjsrnerud 1987) (rogers 1985) 8 dsrdalen formation 150+ 0 8 (hi*): thickness (m) oruinfjellet area heterogeneous dolomite & limestone/white marble phyllitc i thiisdalen formation rcd-brown phyllite & quartzite 200 0 7 (hpm): maroon phyllitc h trinutane formation c ) ferroan dolomite/pink 150 0-6c (hdo): marble orange dolomite b) resinous phyllite 30 0 6 b (hpw): waxy phyllite c) pink, cross-bedded quartzitc 200 5 seljehaugfjellet formation h) grey dolomite 1 so 0 5 h (hdfl): grey dolomite aoatstone a) black lirncstonc so 4 botnedalcn formation 300 0 4 (hlsp): platy limestone, dolomite and phyllite limestone & phyllite 3 peder kokkfjellet formation 60 sandy dolomite 2 evafjellet formation quartzitc & phyllite 1,000:' 1 kapp berg formation 1 ,000? phyllite & quartzite magnethbgda sequence anroniubreen area (hauscr 1982) m-8 ( h b d l ) : banded dolomite/whitc marble m-7 (hdp): dark phyllitc m-6c (hyd): yellow dolomite m-6b (hgq): grey-green quartzite m-6a (hfq): feldspathic quartzite augcn mylonite m-sh (hgd): grey dolomite w/hematite m-2 (hlq): layered quartzite * symbols used by rogers (1985) and hauser (1982) is in the order of 1,500m. the first distinctive unit above the monotonous quartzites is an orange-weathering dolomite which is sandy (locally cross-bedded and oolitic) in the north and rich in white mica in the south. this unit is named for peder kokkfjellet (fig. l), where it is exposed in the core of a large east-closing recumbent fold. the peder kokkfjellet formation is also well exposed on evafjellet and grisryggen. it grades upward into a platy, micaceous limestone-phyllite-dolomite unit, named the botnedalen formation. sedimentary structures (including bedding) are difficult t o discern in this unit, which apparently sustained intense shear strain during proterozoic tectonism. the bot nedalen formation grades into black, thinly bedded, locally oolitic limestone and laminated, stromatolitic (?) grey dolomite (seljehaugfjellet formation). the succeeding unit, the trinutane formation. includes three rock types which define a distinctive stratigraphic package. the formation begins with pinkto orange-weathering, dolomitic 132 m . bj@rnerud quartzite which is gradational from the underlying seljehaugfjellet formation. the lowermost beds of the quartzite are commonly cross-bedded, and contain what appeartobe rip-upclastsof dolomite. the dolomite content decreases upward, and the top of the 200m thick quartzite is slightly feldspathic. the upper part of the trinutane formation consists of green, thinly laminated phyllite with a resinous luster and orange weathering ferroan dolomite studded with centi meter-sized pyrite crystals. in most exposures the resinous phyllite and orange dolomite are tectonically interleaved. in the hinge zones of some mesoscopic isoclinal folds the dolomite has been transformed into a pale pink marble. the trinutane formation is overlain by reddish brown quartzitic phyllite (thiisdalen formation) and a heterogeneous series of dolomites and phyllites ( d ~ r d a l e n formation). these are the youngest preserved nordbukta rocks, exposed on fleyfjellet, d0rdalsnuten and seljehaugfjellet in the inferred hinge of the proterozoic fold nappe (fig. 2 ) . magneth@da sequence as discussed previously, the regional distribution of proterozoic rocks in northern wjl suggests that the magnethogda sequence east of rech erchebreen (hauser 1982) may be correlative with the nordbukta sequence south of dunderdalen. tectonic disruption of the magnethogda sequence and uncertainties about younging direction within it (hauser 1982) make unit-by-unit correlations between the sequences difficult, however. in table 1 magnethogda sequence units are designated by numbers which indicate their possible relationships with the nordbukta sequence. the predominance of carbonate rocks in the magnethogda sequence (hauser 1982) suggests that it may have affinities with the upper division of the nordbukta sequence. hematite-bearing dolomite exposed on jarnfjellet and magneth~gda (unit m-sb) contains apparent algal laminae, dolomitic intraclasts and cross beds, and thus is strongly reminiscent of the transition between the grey dolomite of the seljehaugfjellet formation and pink quartzite of the trinutane formation. feldspathic quartzite (m-6a) and grey-green quartzite (m-6b) exposed north of magnethagda, moreover, are similar to the trinutane pink quartzite and resinous green phyllite. in the magnethogda sequence, however, the arkosic quartzite varies texturally from a clearly sedi mentary rock into a mylonite with cm-sized feldspar augen. no comparable texture has been observed in the nordbukta sequence. similarities between the magnethogda sequence and sub-unconformity rocks of the orvinfjellet area (fig. 1) are particularly noteworthy. the unconformity is particularly well-exposed in this area, and the sub-uncon formity rocks were studied in detail by rogers (1985). because their relationship with nordbukta units is not entirely clear, they are listed by number in table 1. banded grey and white marble (0-8), exposed as flatirons on the west flank of peak 665 m near orvinfjellet, very likely corresponds with magnethogda sequence grey and white marble (m-8) on the lower east side of mariatheresiatoppen. the occurrence of specular hematite bodies on the south side of peak 665 m also suggests a connection with the iron ore bearing magnethogda dolomites. the possible link between the magnethogda sequence and the sub-unconformity rocks west of recherchebreen is critical to interpretations of spitsbergen’s proterozoic and early palaeozoic history because recherchebreen is the proposed site of a major late devonian strike-slip fault zone. harland (1978b) cited the different character of proterozoic rocks immediately east and west of the glacier as evidence for a first order terrane boundary there. an equally plausible explanation is that the trace of the proterozoic angular unconformity continues beneath recherchebreen. metamorphic grade of sub-unconforrnity rocks most mineral assemblages in the nordbukta and magnethogda sequences indicate peak metamorphic conditions within the greenschist facies (hauser 1982; bjornerud 1985; kalinec 1985), for example: -chlorite + muscovite + quartz -chloritoid + muscovite + quartz -dolomite + quartz -calcite + muscovite + quartz. hauser (1982) reported local occurrences of garnet in a magnethogda quartzite (m-6a), but the composition of the garnet has not been studied. cheng (1984) found a small amount of kyanite in a specimen of (evafjellet formation) quartzite collected west of peder kokkfjcllet. upper proterozoic unconformity in northern wedel jarlsberg land 133 this is t h e only known occurrence of kyanite in the sub-unconformity proterozoic rocks, but it suggests that some of the rocks may have experienced amphibolite-facies metamorphism. t h e recrystallized feldspar augen in magnethogda unit m-6a may also indicate moderately high grade metamorphism of parts of t h e magnethagda sequence. further analyses of t h e nordbukta and magnethogda sequence rocks a r e needed to constrain the timing and conditions of meta morphism. supra-unconformity lit hostratigraph y dunderbukra-recherchefjorden sequence t h e stratigraphic complexity of the supra unconformity sequence has been a major reason for the confusion about proterozoic lithostratigraphic correlations within and beyond wedel jarlsberg land. t h e lateral complexity of the sequence, however, also provides glimpses into its depositional environment. kapp lye11 diamicff tes (vendion?) greenschisf/ phytlite dolomite/ llmestone conglomerate late proterozoic angular uncontormity nordbukta sequence magnethbgda sequence fig. 3. lateral thickness and facics variations in the supra-unconformity dunderdalen-recherchefjorden sequence. the underlying nordhukta and magnethogda sequences arc depicted schematically. 134 m . bj0rnerud table 2 . lithostratigraphy of the supra-unconformity proterozoic sequences, wedel jarlsherg land, sw spitsbergen unit estimated probable equivalent in thickness (m) soficbogen group of hornsund area (hjelle 1969; birkenmajer 1981) kapp lyell sequence diamictite, conglomeratc 2,000-3,000 quartzite, phyllite dundekbukta and recherchefjorden sequences dunderdalen formation 1,000-2,000 gbshamna phyllite phyllite, greenschist & metabasalt with local bodies of dolomite &l quartzilc ~ slettfjelldalcn formation dolomite & limestone 50-300 hoferpynten dolomite konglomcratfjcllct formation b) green conglomeratc, 300+ a) brown conglomcratc, 400+ diamictite & quartzite diamictitc & quartzite slyngfjellet conglomerate thiisfjellet formation b) black pyritic limestone 0-100 a ) dolomite gritstone and 0-50 conglomerate u n c o n f o r m i t y (nordbukta sequence) (deilegga group) supra-unconformity proterozoic rocks are exposed in the central part of northern wjl, from kapp lyell southward to the orvinfjellet area. although the rocks in this central area clearly constitute a single depositional sequence, lateral facies contrasts are dramatic enough to make a distinction between a western division, the dunderbukta sequence (exposed from dunderbukta to gmeineryggen), and an eastern division, the recherchefjorden sequence (chamberlindalen to orvinfjellet) (fig. 3). these original depositional contrasts appear to have influenced later caledonian deformational pat terns (bjgrnerud et al. in press), so distinguishing the two subdivisions is also useful from a structural standpoint. in the following discussion the dunderbukta and recherchefjorden (d-r) sequences will be described together, with significant differences between them noted where appropriate. informal formation names are proposed in table 2. four main divisions can be identified within the supra-unconformity sequences (fig. 3). beginning at the unconformity, these include: 1) a succession of coarse clastic rocks, mainly conglomerates and quartzites (konglomeratfjellet formation), and, locally, a basal unit of sandy dolomites and silty limestone (thiisfjellet formation). combined thickness 800 to 1,700 m. 2 ) a series of dolomites and minor limestones (slettfjelldalen formation) with featuresincluding cross-bedding, depositional breccias, stro matolites and chert beds, as well as shallow mafic intrusions in the recherchefjorden (eastern) sequence (50 to 300 m thick). 3) green, silver and black phyllite (dun derdalen formation) containing discontinuous quartzite and dolomite beds and, in the recherchefjorden sequence in chamberlindalen, volcaniclastic rocks and pillow basalts (1,000 to 2,000 m) . 4) the kapp lyell diamictite sequence (per haps 3,000 m thick). within the framework of these four broad divisions there are many local variations in rock type and stratigraphic thickness. upper proterozoic unconformity in northern wedel jarlsberg land 135 basal units: thiisfjellet and konglomeratfellet formations lateral facies changes are most dramatic in the conglomerate succession at the bottom of the supra-unconformity sequence, presumably reflecting a depositional environment with considerable topographic relief. in the dun derbukta sequence three separate conglomeratic horizons within this succession can be traced with reasonable continuity from fl0yfjellet to gmeineryggen : 1 ) thiisfjellet formation: gritstone/con glomerate with greyto orange-weathering dolomitic matrix and highly variable thickness (0 to 50m). from flgyfjellet to buggefjellet this lowermost conglomerate is both interfingered with and overlain by black, pyritic, phyllitic limestone (50 to 100 m thick), containing isolated beds of quartzite pebble conglomerate. 2) konglomeratfjellet formation, lower part: brown conglomerate/diamictite with a dolomitic matrix and pebbleto cobble-sized clasts composed mainly of dolomite. many clasts are fragments of oncolites or stromatolites. some intervals are massive and lack identifiable bedding planes. i n other intervals locm to l m thick graded beds occur. the bedding is locally contorted by apparent soft-sediment folding, faulting and diapirism. about 400 m thick. 3) konglomeratfjellet formation, upper part: green conglomerate/diamictite with a chloritic matrix and pebbleto cobble-sized clasts composed mainly of quartzite. graded bedding and ripplemarks are typical sedimentary struc tures. about 300 m thick. these divisions are not entirely applicable to the recherchefjorden sequence. in the chamberlindalen and orvinfjellet areas the thiisfjellet formation is absent, and the clastic succession as a whole is thicker and coarser grained. on orvinfjellet, where the unconformity is clearly exposed, ‘brown’ and ‘green’ divisions can be distinguished in the lowermost con glomerates (rogers 1985). well-rounded clasts of white, pink and green quartzite probably derived from the pastel quartzites of the lower nordbukta sequence are the predominant types in these boulder conglomerates. higher in the section the clastic sequence near orvinfjellet becomes more similar to the dunderbukta conglomerates and diamictites. graded bedding, laterally discontinuous strata and apparent soft sediment structures are typical of rocks in both areas, and indicate rapid deposition by high energy waterlsediment flows. in addition, oncolite clasts occur in a diamict layer on the ridge northeast of orvinfjellet, suggesting a common source area with the dunderbukta conglomerates. it seems likely, however, that even laterally traceable strata within the conglomerates re present time-transgressive deposits. because the trace of the proterozoic uncon formity is probably obscured beneath rech erchebreen, it is difficult to determine how much of the lower recherchefjorden sequence is concealed in the chamberlindalen area. the oldest exposed recherchefjorden rocks are coarse conglomerates which occur on konglomeratfjellet and brenibba. these rocks are very much like the lowermost conglomerates o n orvinfjellet, with rounded, boulder-sized clasts of white, pink and green quartzite. it seems probable, therefore, that they occupy a similar stratigraphic position near the unconformity. significantly, about 5% of the clasts in the konglomeratfjellet conglomerate have compositions similar to the feldspathic quartzite (unit m-6a) of the magneth0gda sequence. the mean clast size of the recherchefjorden sequence conglomerates decreases northward from konglomeratfjellet. this trend is probably a combination of progressive fining both laterally and upsection. slettjjelldalen formation the slettfjelldalen dolomites and limestones show almost as much lateral viability as the underlying conglomerates and quartzites. cross-bedding, sedimentary breccias, digitate stromatolites and chert beds occur in various permutations in these rocks, suggesting complex spatial and temporal variations in depositional environment. the slettfjelldalen formation has rather different characteristics in the recherchefjorden and dunderbukta subdivisions. first, the unit is considerably thicker in the recherchefjorden sequence (200 to 300 m vs. 50 to 100 m). second, sills and dykes of alkali basalt composition are common in the recherchefjorden dolomites but not in their dunderbukta equivalents. finally, the deformational fabrics of the carbonates in the two areas are very different. sedimentary structures in the recherchefjorden carbonates are modified or obliterated by an intense (caledonian) mylonitic foliation, while the 136 m . bjlrnerud dunderbukta carbonates show only a non penetrative pressure solution cleavage. while this distinction is not a depositional one, it may reflect mechanical contrasts related to original variations in thickness and composition. dunderdalen formation dunderdalen, chamberlindalen and trinutpasset are underlain by an extremely thick (1,000 to 2,000 m), but poorly exposed phyllite unit which overlies the slettfjelldalen formation. the rarity of good outcrops makes stratigraphic relationships within the phyllite obscure, but several distinctive features of the unit are noteworthy. discontinuous beds and lenses of quartzite and dolomite, commonly brecciated, occur from place to place in the phyllite. the limited extent and fragmented internal textures of some of these bodies suggest that they may represent olistoliths transported into an otherwise quiet basin. in chamberlindalen the phyllite contains variolitic pillow basalts and lenses of alkali diabase like that in the underlying dolomites, indicating that volcanism was con current with deposition of the unit (hauser 1982). the phyllite also contains apparent pyroclastic bombs vesicular spheroids 5 to locm in diameter. these objects have been dolomitized, and they typically occur in a very green fine grained phyllitic matrix which may represent metamorphosed volcanogenic sediments. kapp lye11 sequence the contact between the thick dunderdalen phyllites and the overlying kapp lyell diarnictites is somewhat enigmatic. the increased intensity of a secondary foliation close to the contact could indicate that the two units are in tectonic, rather than stratigraphic, contact (hauser 1982; kowallis & craddock 1984). sedimentary featuresindicate, however, that the phyllite-diamictite transition is probably a gradational stratigraphic contact. the uppermost strata of the phyllite unit include coarse-grained quartzites with isolated cobbles and boulders of dolomite. the lowermost beds of the diamictites, in turn, are extremely clast poor, and consist mainly of varve-like laminae of interlayered phyllite and sandy dolomite, with each couplet 0.2 to 1.0cm thick. the phyllite diamictite contact is most likely a stratigraphic transition which was the locus of high shear strain during later deformation. above the basal transition zone, cobbles and boulders punctuate the varve-like layering of the diamictites. these clasts may well be ice-rafted, although the superimposed tectonic fabric makes it difficult to identify clear examples of dropstone textures. the diamictites contain clasts re presentative of almost all underlying rock types, including pelite, limestone and dolomite, which appear to be derived from the post-unconformity sequence. the matrix of the diamictites is largely dolomitic, perhaps derived from carbonate rocks exposed at the time of deposition. graded beds of quartzite, 50 to 100 cm thick, occur at irregular intervals within the otherwise finely laminated rock. these and related features, including flame and injection structures, led waddams (1983) to describe the kapp lyell rocks as ‘resedimented’ glaciomarine deposits. on the macroscopic scale the diamictite sequence defines a nw-plunging synclinorium (fig. 1) which is a second-phase caledonian structure (bjornerud et al. in press). at the mesoscopic scale, however, sedimentary layering in the diamictites is transposed by first-phase isoclinal folds, making the original stratigraphy of the sequence difficult to decipher. depositional setting of the dunderbukta recherchefjorden sequence the following observations summarize dund erbukta-recherchefjorden lithostratigraphy: 1) the sequence is divisible into four major units: conglomerates, dolomites, phyllites/meta volcanic rocks and diamictites. 2) dramatic lateral variations i n rock type and thickness occur within the framework of these four divisions. important differences exist between the post-unconformity strata in the dunderbukta and recherchefjorden areas. 3) sedimentary features of the lower con glomeratic units (konglomeratfjellet formation) indicate rapid and localized deposition by high energy watertsediment flows. 4) mafic volcanic and shallow intrusive activity occurred during deposition of the upper part of the recherchefjorden sequence. collectively, these observations suggest that the supra-unconformity rocks were deposited in an unstable sedimentary environment. the coarse clastic units in the lower part of the sequence probably reflect the topographic relief which existed after late proterozoic deformation of the upper proterozoic unconformity in northern wedel jarlsberg land 137 sub-unconformity sequence. the basalts and related rocks in chamberlindalen indicate that tectonism (rifting?) may also have contributed to the creation of an unstable depositional setting. syn-sedimentary graben formation in an exten sional regime might account for the lateral thickness variations observed in the rocks. it seems likely that most lithologic units in the dunderbukta-recherchefjorden sequence represent time-transgressive deposits, not time horizons. the basal units (thiisfjellet and konglomeratfjellet formations) may be dia chronous deposits which accumulated in topo graphically and/or tectonically controlled basins. the black limestones of thethiisfjellet formation, for example, may represent localized, relatively deep-water deposits. the relatively thick and coarse conglomerates in the east may reflect proximity to the locus of incipient volcanism. the green chloritic matrix of some conglomerates in the dunderbukta and orvinfjellet areas could conceivably be time-correlative with the very green volcanogenic (?) phyllites of chamberlin dalen. if so, the conglomerates in the north would be older than those in the south, possibly reflecting the southward propagation of the volcanic centre with time. interpretation of dunderbukta-recherche fjorden lithostratigraphy is further complicated by probable differences in sedimentation rates for the various units. the conglomeratic units, for example, may have been deposited relatively rapidly, while the dunderdalen phyllites probably accumulated much more slowly. depending on the amount of time represented by the dunderdalen phyllites, the glaciogenic kapp lyell sequence could be only slightly younger than, or much younger than the dunderbukta recherchefjorden sequence. metamorphic grade of dunderbukta recherchefjorden sequence the dunderbukta-recherchefjorden sequence appears to have experienced metamorphic temperatures and pressures no higher than those of middle greenschist facies. as in the nordbukta sequence, chlorite, chloritoid and muscovite are typical metamorphic minerals, and the most common rock types (quartzites and dolomites) are not sensitive recorders of low-grade metamorphic temperatures and pressures. the phyllites, greenschists and metabasalts of the dunderdalen formation offer the best possibility for geo thermometry and -barometry. possible correlations with the hornsund area the close correspondence between the upper hecla hoek rocks in northern wjl and the sofiebogen group near hornsund has been recognized for some time (orvin 1940; winsnes 1965; hjelle 1969). the three formations within the sofiebogen group, the slyngfjellet conglomerate, the hoferpynten dolomite and the g h h a m n a phyllite (birkenmajer 1981), are clear analogs of the konglomeratfjellet, slettfjelldalen and dunderdalen formations, respectively. in detail, the similarities between the bellsundand hornsund-area rocks are even more striking. for example, the ‘brown’ and ‘green’ conglomeratic divisions observed south of dunderdalen have counterparts in the hornsund area. according to birkenmajer (1959, p. 13), ‘two horizons can be distinguished within the (slyngfjellet) conglomerates, the lower one coloured yellow and the upper horizon with green colour prevailing’. in addition, sedimentary features which are common in the slettfjelldalen dolomites (e.g. stromatolites, cross-bedding, chert layers and depositional breccias) also characterize t h e hoferpynten dolomites near hornsund (birkenmajer 1970). lateral variations in stratigraphic thickness and sedimentary facies are typical of both the sofiebogen group and the dunderbukta-recherchefjorden sequence. it is less easy to make direct correlations between the nordbukta sequence and the hornsund-area deilegga group, which lies unconformably beneath the sofiebogen group. the correlation is hampered because the unconformity almost certainly transects the underlying deformed terrane at different stratigraphic levels in different places. discussion and conclusions in summary, a newly-recognized proterozoic angular unconformity in northern wedel jarlsberg land records a period of pre-vendian tectonism. the unconformity truncated the upper limb of a nappe-like fold in the sub-unconformity sequence, leaving the sequence overturned on a regional 138 m. bj@rnerud scale. the age of the proterozoic deformational event is not yet constrained, but it may eventually provide a basis for tectonostratigraphic correlations with proterozoic sequences elsewhere in svalbard and the high arctic. the proterozoic unconformity, associated conglomerates and overlying units can be traced almost continuously from recherchefjorden across torellbreen t o hornsund, defining a major late proterozoic sedimentary province in southern spitsbergen. the supra-unconformity rocks accumulated above a structurally complex basement and regional correlations among sub-unconformity sequences are not clear at this time. the conglomerates which overlie the unconformity may have been shed in an extensional tectonic setting in which syndepositional faulting controlled sedimen tation. these conglomerates are distinct from a sequence of apparently glaciogenic diamictites which lie higher in the section. apparent correlations between suband supra unconformity proterozoic rocks on both sides of recherchebreen and torellbreen are incom patible with the postulated existence of a fundamental paleozoic terrane boundary beneath theseglaciers (harland 1978b). if such a boundary indeed exists, it must lie elsewhere. acknowledgements. this report incorporates the results of dctailcd field studies by the author as well as c. craddock, e. hauser, a . bray, a . chcng, p. cochrane, j. kalinec, b. kowalhs, d. mccord, j . nania, t. phillips, g . rogers and c. wills. principal funding for this study came from national science foundation grant dpp 8203038 to c. craddock. m. bjernerud was supported by national scicncc foundation and university graduate fellowships at uw-madison. logistical support from norsk polarinstitutt in oslo was vitally important to this field-based study. mange takk to t. winsncs, t. siggerud, y. ohta and others at norsk polarinstitutt for their kind efforts on behalf of the wisconsin expeditions to spitsbergen. thanks also to dr. ohta and to anonymous reviewers for comments on the manuscript. references birkenmajcr, k. 1959: report on the geological investigations of the hornsund area, vcstspitsbcrgcn. in 1958. i . hecla hock formation. bull. de 1’acudemie polonaise des sciences birkenmajcr, k . 1970: cross-bedding and stromatolites in thc precambrian hoferpyntcn formation of s ~ r k a p p land, spitsbcrgen. norsk polarinstitutt arbok 1970, 121145. birkenmajcr, j . 1981: the geology of svalbard, the western part of the barcnts sea, and the contincntal margin of scandinavia. pp. 265-329 in nairn, a , , churkin, m. & stchli, f. (eds.): the ocean businsand murgins5, the arctic ocean. plenum prcss, new york. b j ~ r n e r u d , m. 1985: the structure and stratigraphy of vu (2), 129-136. proterozoic rocks in the thirjfellet area, wedel jarlsberg land, west spitsbergen. m.s. thesis, univ. of wisconsin madison. 135 pp. b j m ~ e r u d , m. 1987: structural evolution of a proterozoic metasedimentary terrane, wedel jarlsberg land, sw spits bergen. ph.d. dissertation, univ. of wisconsin. 202 pp. bjernerud, m., craddoek, c. & wills, c. 1990: a major late proterozoic tectonic event in southwestern spitsbcrgen. precambrian research 48. bjbrnerud, m., decker, p. & craddock, c. in press: reconsidering caledonian deformation in sw spitsbergen. tectonics. bray, a. 1985: the structure and stratigraphy of the proterozoic hecla hoek succession near flgyfiellet, wedel jarlsberg land, spitsbergen. m.s. thesis, univ. of wisconsin. 135 pp. chcng, a. 1984: structure of the 7 @ r s l e f t a area, wedel jarlfberg land, spitsbergen. m.s. thesis, univ. of wisconsin. cochrane, p. j. 1984: structure and stratigraphy of the hecla hoek sequence in the turrsjbdalen-breuarsdalen areu. wedel jarlsberg land, w spitsbergen. m.s. thesis, univ. of wisconsin. 172 pp. craddock, c., hauser, e., maher. h., sun, a. & zhu. g.-q. 1985: tectonic evolution of the west spitshergcn fold bclt. tecronophysics 114, 193-211. dallmann, w . , hjellc, a , , ohta, y . , salvigscn, o., maher, h., b j ~ m e r u d , m., hauser, e . & craddock, c. 1990: geological map of svalbard 1: 100,000. shect b l l g van keulenfjordcn. norsk polarinstitutt temakart 15. flood, b., nagy, j. & winsncs, t. s . 1971: geological map of svalbard 1:500,000. sheet 1g. spitsbcrgcn southern part. norsk polarinstitutt skrifter 154a. garwood, e. & gregory, j . 1898: contribution to the glacial geology of spitsbergen. quart j . geol. soc. london 54,197 225, harland, w. b. 1964: evidence of late precambrian glaciation and its significance. pp. 119-149 and 179-184 in nairn, a . (ed.): problems of paleoclimatology. wilcy. london. harland, w. b. 1978a: a reconsideration of late precambrian stratigraphy of southern spitsbergen. polarforschung 48.40 61. harland, w. b . 1978b: the caledonidcs of svalbard, in caledonian-appalachian orogcn of the north atlantic region. geol. survey of canada paper 7&13, 3-11. harland, w. b . , gaskcll, b . , hcaffard, a . , lind. e . & perkins, p. 1985: outline of arctic post-silurian contincntal displacements. pp. 137-148 in spencer, a . m. (cd.): petroleum geology of t/ze north european margin. norwcgian petrolcum society. hauser, e. 1982: tectonic euolution of a segment of the west spitsbergen fold belt in northern wedel jurlsberg land. ph.d. dissertation, univ. of wisconsin. 188 pp. hauser, e.,cochrane, p., zhu, g.-q., chcng. a . &craddock, c. 1983: the structure and stratigraphy of the hccla hock sequence near kapp berg, spitsbergen. geol. soc. a m . ahs. w. progs. 15, 230. hjelle, a . 1969: stratigraphical correlation of hecla hock succession north and south of bcllsund. nortck polurinstrtutt arbok 1967, 46-51, kalincc, j . 1985: the structure and stratigraphy of the seljehaugfjellet urea, wedel jarlsberg land, spitsbergen. m . s . thesis, univ. of wisconsin. 188 pp. kowallis, b. & craddock, c. 1984: stratigraphy and structure of the kapp lyell diamictites (upper proterozoic). spitsbergen. geol. suc. am. bull. 95, 1293-1302. 120 pp. upper proterozoic unconformity in northern wedel jarlsberg land 139 mccord, d. 1978: hecla hoek stratigraphy and structure, south chamberlindalen, spitsbergen. m . s . thesis, univ. of wisconsin. 89 pp, nania, j . 19871 structure and stratigraphy along a major proterozoic 'unconformity, dunderdalen to breuassdalen, wedel jarlsberg land, spitsbergen. m . s . thesis, univ. of wisconsin. orvin, a . 1940: outline of the geological history of spitsbergen. norsk polarinstitun skrifter om sualbard og ishauet 78. 51 pp. phillips, t. 1986: thestructure andstrarigraphy of fhe grisryggen area, wedel jarlsberg land, west spitsbergen. m . s . thesis, univ. of wisconsin. 154 pp. rogers, g. 1985: the structure and stratigraphy of !he proterozoic succession near oruinfjellet, wedel jarlsberg land, spitsbergen. m . s . thesis, univ. of wisconsin. waddams, p. 1983: late precambrian resedimented con glomerates from bellsund, spitsbergen. geol. mag. 120,154 164. wills, c. j. 1984: structure and stratigraphy of the lower oruindalen area, wedel jarlsberg land, spitsbergen. m . s . thesis, univ. of wisconsin. 119 pp. winsnes, t . s . 1965: the precambrian of spitsbergen and bj0rn0ya. pp. 1-24 in rankama, k . (ed.): the geologic systems 2. the precambrian. interscience publishers, ncw york. depth distribution of calanus finmarchicus and c . glacialis in relation to environmental conditions in the barents sea kim h. unstad and kurt s. tande unstad. kim h. & tande, kurt s . 1991: depth distribution of calanusfinmarchicus and c. glacialis in relation to environmental conditions in the barcnts sea. pp. 409-420 in sakshaug. e.. hopkins. c . c. e. & 0ritsland. n. a . (eds.): procecdings of the pro marc symposium on polar marine ecology, trondheim. 12-16 may 1990. polar research lo(2). stage composition and vertical distribution of copepodids of colanus finmarchicus and c. glacialis are described during spring and summer in atlantic and arctic waters, respectively. the two species co occurred in the region of the polar front. both in moderate to high population densities. ontogenetic migration. meaning that the migration range becomes progressively wider with advancing stage. was found in both species. the present study also revealed that c. finmarchicus had modifications in its ontogenetic vertical distribution. the standing crop of phytoplankton, predominantly phaeocysfis pouchefii. appeared to influence the degree of stage-specific segregation. both low and high food concentrations tended to increase the vertical distribution of the instars. on thc other hand, a narrow subsurface stratum of abundant phytoplankton led to an aggregation of copepodids at this dcpth. in the region of the polar front. where the two species co-occur. c. glacialis had a deeper distribution than c. finmarchicus, thus creating a bimodal vertical distribution pattern within the uppermost 200 m. ' l j ~ p o l a r ~ n s ~ ' ' kim h . unstad and kurf s . tande. department of aquafic biology. norwegian college of fishery science. unioersitj of tromsb. n-9000 tromsb, norway. introduction there is a tendency in pelagic environments for zooplankton and its food supply to be patchily distributed on any spatial or temporal scale (dagg 1977). aggregations of zooplankton have been found on horizontal scales of 1-10 km ( k i ~ r b o e 1988), while zooplankton layers, varying in thick ness from a few to tens of metres have been observed vertically (vinogradov 1968; longhurst 1976). the difference in scales is related to the fact that hydro-dynamic and biological variations in the environment are usually greater when con sidered vertically than when considered hori zontally. vertical migration and distribution of zoo plankton organisms have been the subject of extensive research efforts since the 19th century (hardy 1971). in the debate concerning this phenomenon, it has been postulated that the explanations have to be considered at two levels (see vinogradov 1970; bohrer 1980; ringelberg 1980). the phenomenon can, from an evol utionary perspective, be regarded as an adaption to the planktonic way of life (ultimate and teleo logical mechanisms). on the other hand there is the direct response of the individual, both to environmental and endogenous factors. these can be regarded as the instant and directly acting agents (proximate or causal mechanisms). most studies concerning vertical zooplankton migrations have been carried out in temperate regions, where the annual variations in the light and temperature regimes are minor, as compared to polar regions. consequently, the main topics of these studies have been related to die1 verti cal migrations. in high-latitude systems, which exhibit pronounced seasonal variations in day length and temperatures, seasonal and onto genetic vertical migrations are important features of the vertical migration pattern (bogorov 1946; longhurst 1976; buchanan & haney 1980; gron dahl & hernroth 1986; eilertsen et al. 1989). the present study is based on an investigation of the vertical distributions of different devel opmental stages of the calanoid copepod calanus finmarchicus carried out in 1986 in fjords of north ern norway (tande 1988). the study from these inshore waters clearly points out that c . fin marchicus in this region exhibited both die1 and ontogenetic vertical migrations during the spring and early summer. differences in the vertical 410 k . h . unstad & k . s . tande distributions of the copepodids were related to differences in environmental conditions (i.e. tem perature and phytoplankton abundance) and in population densities of c. finmarchicus between the locations. the study suggested that the ver tical separation could be an important mechanism in reducing the competitive interactions among the copepodids of c. finmarchicus. based on samples taken at three time periods in may, the response of the different developmental stages to the environmental conditions was found to be continuously modified throughout the most inten sive growth and recruitment period of c. fin marchicus. this complex behaviour pattern of c. fin marchicus in inshore waters could have been mediated by local environmental factors such as topography and tidal action. therefore, the potential effect of hydrographic variability of coastal water might have obscured the behav iourally copepod-generated distribution pattern. thus, in order to readdress this question specifi cally related to the vertical behaviour of c. fin marchicus in an anticipated more homogeneous physical environment, a new study was under taken in offshore waters in the barents sea. the time period selected in may and june is con sidered to be the period of culmination of the spring bloom in atlantic waters (tande 1991 this volume). thus it is likely that the herbivorous zooplankton grazing balances the carbon pro duction at least in certain areas (tande & slagstad 1991). it is expected that the copepod community displays a vertical distribution pattern that leads to an optimal utilisation of the standing stock of phytoplankton (see lane 1975; bohrer 1980; williams & conway 1980; tande 1988). the present study was undertaken in order to describe the vertical distribution of c. finmarchicus i n different vertically structured phytoplankton en vironments; it aimed at delineating any con sistent pattern between the vertical distribution of c . finmarchicus and the physical and biological environment. the area selected was a transect from 73"n to 75" 30" in the western part of the barents sea. the area was sampled twice in the period from 26 may t o 13 june 1987, cor responding to the same biological period, and with exactly the same methodological approach as the preceding year in inshore waters in northern norway. materials and methods sampling programme sampling was accomplished during a survey with r / v endre d y r b y , from 26 may to 13 june 1987. a series of 3 stations along a transect between 73'00" 28'00'e and 75'30" 30'00'e was taken at the start of the cruise and was repeated at approximately the same locations (except for sta tions 6 and 17) at the end of the cruise 14 days later (see table 1 and fig. 1). station time varied slightly, but most of the collections were carried out between 0830 and 1400 cet (central euro pean time), except at station 1 (110g1910 c e t ) . hydrography and light conditions conductivity, temperature and density measure ments (ctd) were performed using a neil brown instruments smart ctd coupled to a hewlett packard computer. in order to construct the iso plots in fig. 2, hydrographic measurements from stations at 73'30" 28"oo'e and 74'30" 30'00'e were used, in addition to the sampling stations shown in fig. 1. since surface irradiance is toble i. timing. position. weather and dcpth data for the diffcrcnt sampling stations ( s t n . ) . wind speeds were measured at start of sampling. cloudincss depth wind stn. date timc (cet) position ( ? t ) (m) ( m / s ) 1 26.05 11w1910 73"oo'n 28"o'e w i w 333 4.6 3 28.05 0845-1j00 74"w'n 28"w'e 100 402 9.8 6 31.05 085&1355 74"30'n 30"w'e 9c-100 365 1 .0 13 09.06 08401405 73"oo'n 28"w'e 100 333 4.6 15 11.06 083g1325 74"w'n 28"oo'e 100 102 4.6 17 13.06 0 8 6 1 3 1 5 75"oo'n 30"oo'e 1 ou 387 9.8 depth distribution of calanus 411 80° 7 0' 76" fig. 1 . map of the barents 74" sea showing the investigated area and the sampling stations (1-17). also shown are the 72' average position of the polar front (stippled line) and the surface currents: arctic currents (broken arrows), atlantic currents (solid arrows) and coastal currents (stippled arrows). 68' (1987). 70" approximately inversely proportional to cloud coverage (kuz'min 1972), data for the latter were used to detect major differences in the light regimes of the sampling locations. plankton zooplankton was sampled by means of a pump system (see solemdal & ellertsen 1984) which consists of a 90" bent glass fibre tube with a diameter of 40 cm. a plankton net (180 pm mesh) was mounted on the vertically-oriented outlet while the impeller was positioned on the hori zontally oriented opening. samples were taken at discrete depths from the surface down to a depth of 195 m, at 15 m intervals. no sampling from the deeper water masses was carried out. pumping time was set to 6 minutes and water flow was measured with a tsk (tsurumi-seiko-kosha kusho co. ltd.) flowmeter. the flow rate varied, probably related to the position of the pump relative to the currents, and the values typically varied between 5 and 10 m3 min-i. for the collection of phytoplankton, a 5 liter. 20' 25' 30' 35' 40' 45' 50" 5! niskin water bottle was mounted externally on the pump. the closing mechanism was remotely controlled by the power source of the pump in such a way that the bottle was closed at the initiation of pumping. both zooand phy toplankton samples were preserved in 2% for maldehyde in seawater, buffered with borax. 50% (by volume) 1.5 propane diol, which functions as a bacteriacide that also helps keeping setae and appendages soft, was added to the zooplankton conservation medium. in the laboratory, the calanus specimens were identified and counted using a wild m3 stereo microscope at either 16 or 4 0 ~ magnification, depending on copepod size. the different stages of calanus spp. were assigned to species using the prosome lengths given in table 2. samples containing large numbers of copepods were split into ten using a lea-wiborg splitter (wiborg 1951). the number of fractions analysed was adjusted so that 50 o r more were counted for each copepodid stage. this procedure gives an estimated value that deviates by less than 30% from the real sample size (aksnes 1981). from the 412 k . h . unstad d k . s. tande 73 0 74 0 75 0 fig. 2. isoplots showing temperature (upper) and salinity (lower) for series 1 (left) and series 2 (right), 73 0 74 0 7 5 0 latitude i n l respectively resulting copepod densities, the total population size could be estimated by simple plane integra tion. phytoplankton was identified and counted from duplicate subsamples, according to the method described by utermohl (1958). during this process a wild heerbrugg inverted micro scope was used at 2 0 0 ~ magnification. results hydrography and p h y f o p l a n k f o n there was a general decrease in temperature going northwards in the area of investigation in both of the series (fig. 2 ) . n o thermal strati fication was seen, except for the most northern area at 75.5"n i n series 1 (station 6). isotherms show that temperatures generally decreased between 0.5 and 1.o"c from surface down to a depth of 195 m. in such a way that the differences in surface values between areas tended to persist down to the deepest depth of sampling. salinity showed little temporal and spatial variation, rang i n g from 35.15 to 35.25%. a decrease in salinity was found in two regions at 74"n (station 3) and 75.5"n (station 6) in series 1, respectively, with low surface salinities (<35.00%0) due to meltwater from sea ice. the phytoplankton communities of all sampling locations were dominated by the prymnesiophyte phaoecystis pouchetii. although other phyto plankton groups were present, the degree of dom inance of p . pouchefii was so high that this species was considered as representative of the food avail table 2 . calanur app. identification kcy for c. finmarchicus ( c f i n ) . c. glocialis (cgla) and c. hvperboreus (chyp). modified from hassel (unpubl.). prosome length ( m m ) stage cfin cgla chyp ci c0.85 0.85-0.90 n . 9 0 cii <1 20 1.2& 1.42 > 1 . 4 2 clll 1 1 . 6 5 1.65-2.15 >2.15 civ 1 2 . 3 0 2.3w3.00 >3.w cv 1 3 . 0 0 3.0-3 40 >3.40 females <3.20 3 2 k 4 . 5 0 >4.50 depth distribution of calanus 413 20 i o stat!on 1 30 w 0 4 station 13 m fig. 3. calanus finmarchicur. stage composition at all stations in the two series able for the copepods. therefore, the phyto plankton conditions will be described here with respect to p. pouchetii only. as shown in table 2, the mean values for cloud coverage varied between 90 and 100%. thus no great differences in light conditions between the stations could have been caused by variability in cloudness. calanus finmarchicus: temperature, phytoplankton, and vertical distribution of copepodids. series 1 . in the first series, station 1 exhibited the highest sea surface temperature (3.6"c) com pared to the other two stations further north (fig. 4). the abundance of p. pouchetii varied greatly between stations 1, 3 and 6. at station 1, the lowest phytoplankton standing stock was found. the number of p. pouchetii was highest at 30 m depth, with 1.27 x 106cells i ' . below this depth, cell numbers were low. the copepodite stages in the population of c . finmarchicus at station 1 were represented in relatively equal proportions (see fig. 3 for stage composition). however, the population, which was estimated to a total size of 8141 individuals m-', contained a somewhat higher proportion (30.2%) of ciii. the depth of station 3 station 6 station 15 n = 66.987 copepodids station 17 maximum occurrence increased with each stage (fig. 4): ci and cii had their highest numbers at 45 m, ciii at 60 m, and civ and cv at 75 m and 165 m, respectively. the adult females were most numerous at 180 m. at station 3 the surface temperature was approximately 3.4"c, steadily decreasing to 2.2"c at 200m depth. the phytoplankton peaked at 75 m of depth, with maximum in p . pouchetii of 2.37 x lo6 cells i ' . the copepod abundance and stage composition was clearly different from station 1: ci made up 73% and thus totally dominated in the population of 52,000 individuals m-2. the vertical distribution pattern was almost similar to that at station 1, except for the tendency of cv and adult females to occupy a shallower depth (see fig. 4). at the northernmost station (station 6) the vertical temperature profile was characterised by cold surface water overlying deeper water masses with a temperature of approximately 1.2"c. the bulk of phytoplankton was found between the surface and a depth of 60 m. where the cell num bers peaked at 30m with 10.4 x 106cells1-'. here, c. finmarchicus was found at the lowest abundances recorded during the investigation (5300 individuals m-2). a bimodal stage dis tribution was seen in which the population con sisted of primarily cv and adult females (see 414 k . h . unstad & k . s . tande % 0 20 40 60 80 100 ---% .*..-a 120 200 160 ~ % 0 20 40 60 80 100 % r-- f,,,, i cell numbers ( x 1 0 6 i ' ) stn 6 0 1 2 3 4 temperature ("c) f i g . 4. vertical distributions of calanurfinmarchicus and phaorytis pouchcrti cell numben. together with temperature profiles at stations 1 , 3 and 6 . fig. 3). in addition t o a lesser proportion of the smallest copepodids (ci and ciii). vertically, ci and cii had their highest numbers at 30 and 45 m. respectively. thus resembling the population dis tributions at stations 1 and 3 (fig. 4). in contrast to all the other sampling locations. the two most advanced instars occupied shallower depths and had a depth of maximum occurrence a t 30 m . series 2 . sampling of the same area two weeks later showed a temperature in the upper water layers which was in general higher than that found at corresponding locations in series 1. a t station 13 a surface temperature of 3.9"c decreased slightly with depth (fig. 5). the phytoplankton was present a t notably abundances only in the uppermost 45 m of depth. t h e highest abundance of copepodids throughout the whole survey was found at this station (62,000 individuals m-?). ciii dominated with 45% of the total population. cii and c i v were each represented by almost 20%, while ci constituted t h e smallest proportion of the population (see fig. 3). a clear ontogenetic vertical distribution was seen, with the majority of the entire population found below the surface maximum in cell numbers (fig. 5). depth distribution of calanus 415 yo % 80 120 n=69.22 1 stn 13 160 200 i i l l 1 1 1 n=66.987 stn 15 n 20 n=51.255 120 160 200 cv ..-*.q civ w 0 1 2 3 4 temperature (%) fig. 5. vertical distributions of calanusfinmarchicus and phaocysris poucherii cell numbers. together with temperature profiles at stations 13. 15 and 17. a surface temperature of 3.6"c was found at station 15, with a slightly more pronounced ver tically decrease in temperature compared to the former location. the phytoplankton was found in very high abundance in the uppermost waters, where phaeocystis pouchetii peaked in maximum abundance (13.9 x lo6 cells 1-i) at 15 m of depth. the total abundance of calanusfinmarchicus was found at about the same size as that at station 13 (fig. 3). the majority of the population appeared as cii, chi and civ, and was located in the uppermost 45 m of depth. at the northernmost station surface tempera tures were approximately 2"c, and decreased to 1.3"c 'at 170 m (fig. 5). the greatest standing crop ever recorded during the investigation was found at cell densities of approximately 6 x 10' i ' in the uppermost 6 0 m of depth. the abun dance of c . finmarchicus was relatively high also at station 17. out of a population of 51,300 individuals m-? (fig. 3), ci and cii made up 36 and 31%, respectively, and thus constituted the largest proportion of the population. relatively low abundance of civ and moderately high num bers of cv and adult females resulted in a bimodal stage-distribution pattern at station 17, a situation 416 k. h . unstad & k . s . tande station 6 station 1 7 5 n = 6 0 5 3 n = 1 3 6 9 5 copepodids fig 6 cokanns glucrolrr srage composition dt stations 6 and 17 which also was seen at stations 6 and 3. the various stages were distributed vertically from 40 to 8 0 m of depth, although with a tendency for a larger vertical spread, especially pronounced among cv and adult females (see fig. 5). calanus glacialis: temperature, phytoplankton and vertical distribution of copepodids. calanus glacialis was abundant only at the two northernmost sampling locations, stations 6 and yo 0 0 20 40 60 80 100 80 40p=.i 120[ % 0 20 40 60 80 100 i clll civ 13 (see figs. 6 and 7). the following information i n the data set is emphasised: at station 6, c . glacialis was present i n low numbers. estimated at 6053 m ? . the population was composed mainly of two groups of instars, the majority of which were copepodid stages i and 11, representing50.9 and 21.7%, respectively. cv. which constituted 18.2%, made up the second group. the two early copepodite stages (ci and cii) were found between 30 and 9 0 m , while the more advanced stages displayed a wider depth distribution, having been recorded at depths between 30 and 105 m (fig. 7). low num bers of cv and adult females were found at all depths, except for a peak in distribution at 30 m , which was somewhat shallower than the younger stages. samples taken two weeks later and 30 nautical miles further south (station 17) contained greater amounts of calanics glacialis and the total popu lation size was estimated to 13.695 individ ualsm-2 by plane integration. of this, the first three copepodite stages made up more than 75% (26.6 ci, 24.9% cii and 23.7% ciii), while the rest of the population was mainly composed of % cell numbers (x106 i" ) n=6.053 0 2 4 6 8 10 -7p-10.37 i t 7 i i stn 6 i i i 1 i i i i k rj m [ stn 17 0 1 2 3 4 temperature ("c) fig. 7. vcrtical distributions of calanur glacialir and phaocpsrij poucltefii cell numhcrr. togcthcr w i t h tcrnpcraturc profilca at stations 6 and 17. depth distribution of calanus 417 copepodids in stages iv and v. at station 17, all the copepodid stages of c. glacialis were recorded at all sampled depths (fig. 7). the tendency for successively larger stages to have shallower depths of maximum occurrence, as could partly be seen at station 6 , was clearly evident at station 17. a tendency towards a bimodal depth distribution was also seen, especially in copepodite stage v. correlation analysis a correlation analysis was performed on untrans formed depth values of the numbers of each devel opmental stage. the resulting values were then used in a mds (multi-dimensional scaling) analysis. the spread in coordinates representing depth distributions of the different populations (fig. 8) is seen mainly along the horizontal axis (dimension). the largest distance is between the coordinates representing depth distributions for calanusglacialis at station 17 and c. finmarchicus at stations 1 and 6. on the other hand, the coor dinates for c. finmarchicus at stations 13, 15 and 17 may be considered to constitute a group. the coordinates representing the vertical distribution pattern of c. finmarchicus at station 15 are seg regated from this group, mainly along the vertical axis (dimension 2). discussion calanusfinmarchicus, together with its two sibling species c. glacialis and c . marshallae, constitutes a group that is distributed over the entire atlantic north of 40” latitude, and throughout the barents sea, the polar basin and the northern pacific (jaschnov 1961,1970; matthews 1969, fleminger & kulsemann 1977; frost 1974). in the barents sea, c. finmarchicus is mainly found north of the polar front area (see fig. l ) , while c. glacialis is an indicator species of water masses of arctic origin and consequently has its main area of dis tribution north of the polar front (see jaschnov 1961). the area of the present investigation was located in the atlantic part of the barents sea, with the exception of the most northerly area, and c. finmarchicus was the dominating copepod species. at the two stations near the polar front, c. glacialis was present in the same order of magnitude as c. finmarchicus. length ranges of c. finmarchicus and c. gla cialis have been shown to overlap, and a plasticity 1 i 16 8 f15 dimension 1 fig. 8. mds plot showing coordinates representing the vertical distributions of colunurfinmurchrcus (f) and c. glociolrs (g) at the different stations (numbers). in body lengths appears when comparing popu lations from different regions (frost 1974). the relatively slight degree of morphological diver gence further complicates distinguishing between the two species when analysing zooplankton samples. length-frequency distributions that were constructed during the analysis of the present material (unstad unpubl. results) showed that the prosome lengths of copepodids of the two species showed some degree of overlap. over lapping “tails” of the distributions, however, were considered not to give more than marginal effects in distinguishing the two species when they occurred in equal proportions of abundance. at the same time, the use of prosome lengths would lead to a substantial over-estimation of one species if it was represented by a very small frac tion as compared to the other species. the annual spring bloom in the barents sea is characterised by the presence of large amounts of the prymnesiophyte phaeocystis pouchetii (zen kevich 1963). although inter-annual variations in species composition appear (e. n~st-hegseth pers. comm.), there is a trend towards phaeocystis domination in high latitudes, which is especially pronounced for the period after the culmination of the spring bloom (eilertsen et al. 1981). in the area of investigation, both population size and vertical distribution of p . pouchetii varied and the highest cell numbers were found between depths 418 k . h . unstad & k . s . tande of 15 and 60 m. there was also a tendency for the phytoplankton standing crop to be larger at the more northerly locations. the fact that relatively high cell densities were found down towards depths of 150m indicates that the bloom in the area of investigation was in its culminating phase during this study (h. c. eilertsen pers. comm.). even though the dominance of phaeocystis pouchetii may theoretically have been a conse quence of selective grazing by zooplankton upon other phytoplankton taxa. p . pouchetii is regarded as the main food source for the herbi vorous zooplankton during the research period. although the trophic fate of this species has been discussed for years, p . pouchetii is consumed by calanus finmarchicus and other members of this genus (turner 1984; tande & bamstedt 1987; hansen et al. 1990b). huntley et al. (1987) found that p . pouchetii alone could sustain the nutrient demands of c . hyperboreus in terms of carbon. in the life cycle of p . pouchetii, both small, flagellated solitary cells and colonies comprising non-flagellated cells appear. the colonies are often larger than 200 pm in diameter. according to hansen et al. (1990b), particles with an equiv alent spherical diameter (esd) of 50 pm are in the upper proportion of the size range of food particles suitable for stage 1-111 copepodids of c . finmnrchicus. during the culmination of the spring bloom, the fraction of disintegrating col onies increases (hansen et al. 1990b). colonies in this state may be easier for the small cope podites to consume. during the period of investigation, the greatest proportion of the c. finmarchicus population inhabited depths from 15 to 100m. copepodid stages i and i1 (ci and cii) were generally found at depths of less than 50 m, while ciii and civ tended to be located above 120 m depths. cv and adult females generally inhabited the upper 100 m of the water column, but the distributions within this depth interval varied between the stations. at one instance (station 1). the greatest pro portions of cv and adult females were found at depths of nearly 200 m. the deeper limit of ver tical distribution can be seen in relation to coexisting copepods; samples from depths greater than 100 m typically contained large amounts of metridia spp. and pseudocalanus spp. (unstad unpubl.). low numbers of calanus spp. in the upper 15m of the water column at all stations except station 15 may be related to illumination preferences. with light intensities near the surface possibly exceeding the light optimum (see boden & kampa 1967) of the animals. no samples were taken from depths greater than 195 m, but as very few copepodites were found in the lower part of the sampled depth range this may indicate that no substantial part of the population was located at greater depths. the vertical distribution patterns indicate an existence of ontogenetic vertical migration in c . finmarchicus at stations 1,13,15 and 17. at these locations, successively older copepodids tended to be located deeper in the water column than the younger developmental stages. n o such tendency was found at station 6, but this locality differed strongly from the other stations in displaying a stratification where the upper part of the water column showed temperatures lower than the rest of the sampled depth interval. additionally, c . finmarchicus co-occurred in relatively low num bers with c . glacialis (see below). the degree of stage-specific segregation seemed to be related t o the vertical distribution of phytoplankton biomass and to the relative abundance of food available t o the copepods, i.e. phytoplankton biomass versus copepod popu lation size. at stations 6, 13 and 15, the verti cal phytoplankton distributions revealed distinct depth-specific peak levels of algal biomass, and the c . finmarchicus populations tended to aggre gate in these depth strata. at station 17, the phytoplankton was vertically dispersed and high cell numbers were found from the surface down to depths of 135 m. at this location the degree of stage-specific segregation was greater than at the previously mentioned stations and the depth stra tum inhabited by each stage was wider. at station 1, where phytoplankton cell numbers were low throughout the sampled depth interval, the ver tical dispersion was pronounced. however, this tendency was not as clear at station 3, even though cell numbers were low also at this location. a small peak in the number of phytoplankton cells at 75 m, together with a high number of copepodid stages i and i1 at station 3, are features that distinguish this station from station 1. it is difficult to conclude that this might account for the difference in dispersion among instars between the two stations. at this point, the present data set is insufficient and further infor mation is needed. at stations 6 and 17, the arctic species c . glacialis was found in the same order of magnitude as the populations of c. finmarchicus. at both depth distribution of calanus 419 the present study reveals that c. finmarchicus showed modifications in its ontogenetic vertical distribution. both low (station 1) and high food concentrations (station 17) appeared to increase the vertical distribution of the instars. on the other hand, a narrow subsurface stratum of abun dant phytoplankton led to an aggregation of cope podites at this depth (stations 6, 13 and 15). the observed shifts in ontogenetic vertical distri butions in c. finmarchicus in high latitude off shore and inshore (tande 1988) waters could thus be explained by changes in food availability. although the present study does not facilitate an examination of alternative causal relationships, similar future studies should encompass the species complexities at the study site, including physical processes and predation. the monitoring of the same body of water for a time period of several weeks is a prerequisite for future inves tigations of any causal relationships aimed at improving our understanding of vertical behav iour in zooplankton. stations, ci dominated, but at station 17, a large proportion of cii-civ was also found. as for c. finmarchicus at these stations, the copepodids of c. glacialis displayed a depth distribution with a small degree of overlap between the different stages. the ontogenetic tendencies in the vertical distributions of c. glacialis were inverse to those of c. finmarchicus, so that the youngest stages of c. glacialis were found at depths greater than those where advanced stages were found. this contrasts with the findings of hansen et al. (1990a), where the older stages of c . glacialis were found deeper in the water column than the younger copepodites. however, williams & conway (1980) demonstrated an inverse stage specific vertical distribution in c. finmarchicus as compared to the congenric species c. helgo landicus in the north sea and the celtic sea, resembling the differences in vertical distributions between c. finmarchicus and c. glacialis found in the present study. at station 17, the population of c. glacialis was spread more vertically than its sibling species and could be found throughout the whole interval from 15 to 180 m. in this way the bulk of c. glacialis had the deeper distribution of the two species, a tendency similar to what was found by herman (1983) in baffin bay. even though there was less vertical spread between the two calanus species at station 6, similar dif ferences between the vertical distributions of the two species could also be seen here. the grouping of the coordinates which rep resent the vertical distribution patterns of calanus finmarchicus at stations 3, 13 and 17 by the mds analysis illustrates their similarity. the increased distance between these points and the coordinate representing the c. finmarchicus profile at station 15 are most likely related to the upward shift in the latter profile, as compared with the three previously mentioned. the position of the coor dinate representing the c. finmarchicus profile at station 1 near the ones representing both this species and c. glacialis at station 6 may be due to the relatively low representation of both species at these two stations. the differences in onto genetic distribution patterns between the two sib ling species are reflected by the position of the coordinates representing the two species at sta tions 6 and 17 some distance apart from each other. the relatively large distance between the points representing c. glacialis at the two stations may be related to the differences in population sizes of this species. acknowledgements. -the authors would like to thank b . vaaja for analysing the phytoplankton material. constructive criticism from anonymous referees is also appreciated. references aksnes, d . l . 1981: undersekelse av zooplankton popu lasjonsdynamikk i lindhspollene. 1979. cand. real. thesis. university of bergen. 122 pp. boden, b . & kampa. m . 1967: the influence of natural light on the vertical migrations of an animal community in thc sea. symp. zool. soc. lond. no. 19, 15-26. bogorov, b . g. 1946: peculiarities of diurnal vertical migrations of zooplankton in polar seas. j . m a r . res. 6, 2 6 3 2 . bohrer, r . n. 1980: experimental studies on die1 vcrtical migration. pp. 111-121 in kerfoot, w. c. (ed.): eoolurion and ecology of zooplankton communities. university press of new england. buchanan, c . & hancy. j . 1980: vertical migrations of zooplankton in the arctic: a test of the environmental controls. pp. 6%79 in kerfoot, w. c. ( e d . ) : eoolution and ecology of zooplankton communities. university press of new england. dagg, m . 1977: some effccts of patchy food environment on copepods. limnol. oceanogr. 22, 99-107. eilertsen. h. c.. schei. b . & taascn. j . p. 1981: lnvestigations of the plankton community of balsfjorden. northern norway. the phytoplankton 1976-1978: abundance, species com position and succession. sarsia 66, 126-141. eilertsen. h. c . . tande. k. s . & taasen. j . p. 1989: vertical distributions of primary production and grazing by colanus glacialis jaschnov and c . hyperboreus kreyer in arctic waters (barents sea). polar biol. 9, 253-260. 420 k . h . unstud & k . s . tande fleminger, a. & hulsemann. k. 1977: geographical range and taxonomic divergence in north atlantic calanus f c . helgolandicus. c. finmarchicus and c. glacialis). mar. biol. 40. 233-238. frost, b. w. 1974: calanusmarshallae. a new speciesofcalanoid copepod closely allied to the sibling species c. finmarchicus and c . glacialis. mar. biol. 26. 77-99. grondahl. f. & hernroth, l. 1986: vertical distribution of eopepods in the eurasian part of the nansen basin. arctic ocean. pp. 311-320 i n schriever. g , schminke. h . k . & shih. c . t. (eds.): proceedings of the 2nd. inr. conference on copepoda, oftawa. syllogeus no. 58, ortawa. hansen. b., berggreen. u c.. tande. k. s. & eilertsen. h. c. 1990a: post-bloom grazing by calanus glacialis. c . finmarchicus and c . hyperboreas in the region of the polar front. barents sea. mar. biol. 104. 5-14. hansen. b., tande. k. s. & berggreen. u. c. 199ob: on the trophic fate of phaeocystis pouchetii (hariot). 111. functional responses in grazing demonstrated on juvenile stages of cal anus finmarchicus (copepoda) fed diatoms and phaeocystis. j . plankron res. 12. 1173-1187. hardy. a. c . 1971: the open sea. part 1. the norld of plank ton. 2nd. ed. collins. 335 pp. herman, a . w. 1983: vertical distribution patterns of copepods. chlorophyll and production in northeastern baffin bay. limnol. oceanogr. 28. 709-719. huntley. m., tande. k . s . & eilertsen. h . c . 19x7: on the trophic fate of phaeocysris poucherii (hariot). i i . grazing rates of calanus hyperboreus ( k r ~ y e r ) on diatoms and dif ferent size categories of phaeocystis pouchetii. 1. exp. mar. biol. ecol. 110, 197-212. jaschnov. w . a . 1961: water masses and plankton. 1. species of calanus finmarchicus s.1. as indicators of definite water masses. zool. z u r n a l 4 0 . 1314-1334 (translated from russian by n. f. c. owen. scottish mar. biol ass. oceanogr. lab.. edinburgh. 1961). jaschnov. w . a . 1970: distribution of calanus species in the seas of the northern hemisphere. int. reoue. ges. hydrobiol. 55. 197-212. kiarboe. t. 1988: p l a n k t o n f ~ d e k ~ d e n : bioenergetiske og oko logiske studier. isbn 87-7481-550-4. danmarks fiskeriog haoundersmgelser. 51 pp. kuz’min. p. p. 1972: melting of snow cover. israel progr. scr. translations. jerusalem. lane. p . 1975: the dynamics of aquatic systems: a comparative study of the structure of four zooplankton communities. ecol. monogr. 45, 307-336. longhurst. a . r. 1976: vertical migration. pp. 116-139 in cushing. d. h. & walsh. j . j . (eds.): the ecology o f t h e seas. blackwell. oxford matthews. j . b. l. 1969: continuous plankton records: the geographic and seasonal distribution of calanusfinmarchicus s. l. in the north atlantic. bull. mar. ecol. 6, 251-273. midttun, l. & loeng. h. 1987: climatic variations in the barents sea. pp. 113-127 in loeng, h . (ed.): the effect of oceanographic conditions on distribution and population dynamics of commercialfish stocks in the barents sea. proc. 3rd soviet/nonvegian symp.. murmansk 2 6 2 8 may 1986. inst. mar. res.. bergen. ringelberg, j . 1980: introductory remarks: causal and teleo logical aspects of diurnal vertical migration. pp. 6 5 4 8 in kerfoot, w. c. (ed.): eoolution and ecology of zooplankton communities. university press of new england. solemdal p. & eliertsen, b. 1084: sampling fish larvae with large pumps; quantitative and qualitative comparisons with traditional gear. flodeuigen rapporfser. 1. 335-363. tande. k. s. 1988: an evaluation of factors affecting the vertical distribution among recruits of calanus finmarchicus in three adjacent high-latitude localities. hydrobiologia 167/168. 115-126. tande. k. s. 1991: calanus in north norwegian fjords and in the barents sea. pp. 389-407 in sakshaug. e.. hopkins. c. c. e. & britsland. n. a . (eds.): proceedings of the pro mare symposium on polar marine ecology. trondheim. 12-16 may 1990. polar research 10(2). tande. k. s. & bsmstedt. u . 1987: on the trophie fate of phaeocysris pouchetii. 1. copepod feeding rates on solitary cells and colonies of p. pouchetii. sarsia 72, 313-320. tande. k . s. & slagstad. d. 1991: regional and interannual variations in biomass and productivity of calanus fin marchicus in subarctic environments. oceanologica acta. i n press. turner. j . t . 1984: the feeding biology of some zooplankters that are important prey items of larval fish. n o a a techn. rep. nmfs7. 28 pp. utermohl. h . 1958: zur vervollkommnung der quantitativen phytoplankton-methodik! m i t t . int. verein. theor. angew. limnol. 9. 1-38. vinogradov. m. e. 1968: vertical dhtribution of the oceanic zooplankton. nauka publ. house. moscow (translated from russian to english. 1970. israel progr. sci. translations, jerusalem. 320 pp.). wiborg. k. f. 1951: the whirling vessel. an apparatus for fractioning of zooplankton samples. fiskeridir. s k r . ser. haounders. 9, 1-16. williams. r . & conway. d . 1980: vertical distributions of calanus finmarchicus and c . helgolandicus. mar. biol. 60, zenkevich. l. 1963: biology of the seas ofthe ussr. allen and 57-6 1. unwin. 995 pp. doi:10.3402/polar.v33.22483 r e s e a r c h / r e v i e w a r t i c l e species distribution and depth habitat of recent planktic foraminifera in fram strait, arctic ocean theodora pados1 & robert f. spielhagen1,2 1 department of paleoceanography, geomar helmholtz centre for ocean research kiel, wischhofstraße 1-3, de-24148 kiel, germany 2 academy of sciences, humanities, and literature mainz, geschwister-scholl-straße 2, de-55131 mainz, germany keywords planktic foraminifera; fram strait; arctic ocean; depth habitat; n. pachyderma (sin.); t. quinqueloba. correspondence theodora pados, department of paleoceanography, geomar helmholtz centre for ocean research kiel, wischhofstraße 1-3, de-24148 kiel, germany. e-mail: tpados@geomar.de abstract to describe the horizontal and vertical distribution of recent planktic foraminifera in fram strait (arctic), plankton samples were collected in the early summer of 2011 using a multinet sampler (�63 mm) at 10 stations along a west�east transect at 78850?n. five depth intervals were sampled from the sea surface down to 500 m. additionally, sediment surface samples from the same locations were analysed. the ratio between absolute abundances of planktic foraminifera in the open ocean, at the ice margin and in the icecovered ocean was found to be approximately 2:4:1. the assemblage was dominated by the polar neogloboquadrina pachyderma (sin.) and the subpolar turborotalita quinqueloba, which accounted for 76 and 15% of all tests in the warm, saline atlantic waters and 90 and 5% in the cold and fresh polar waters, respectively. both species had maximum absolute abundances between 0 and 100 m water depth, however, they apparently lived shallower under the ice cover than under ice-free conditions. this indicates that the depth habitat of planktic foraminifera in the study area is predominantly controlled by food availability and not by temperature. the distribution pattern obtained by plankton tows was clearly reflected on the sediment surface and we conclude that the assemblage on the sediment surface can be used as an indicator for modern planktic foraminiferal fauna. to access the supplementary material for this article, please see supplementary files under article tools online. planktic foraminifera are protozoa that inhabit the upper part of the water column in the world oceans. as their species distribution in high latitude oceans reflects properties of their habitat (i.e., water temperatures and the position of the summer sea-ice margin), fossil assemblages in sediments are often used to reconstruct palaeoenvironments. however, for a correct interpretation of fossil data, it is important to improve our understanding of the correlation between environmental variability in the ocean and the related distribution of living foraminifera. it is particularly essential to reveal the actual depth habitat of recent specimens, as the water properties reconstructed from their fossil calcite shells must be attributed to correct water depths. many studies on recent planktic foraminiferal distributions were conducted in tropical/subtropical areas (e.g., bé & hutson 1977; andrijanic 1988; naomi et al. 1990; kuroyanagi & kawahata 2004), while rather few studies concentrated on (sub-)arctic regions, mainly on fram strait. hansen & knudsen (1995) published data from freemansundet, svalbard, carstens & wefer (1992) presented results on recent foraminifera in the nansen basin, and kohfeld et al. (1996) analysed samples from the northeast water polynya. close to our work area, studies have been conducted by carstens et al. (1997) and volkmann (2000), who showed that planktic foraminiferal species composition in fram strait is dominated by polar neogloboquadrina pachyderma (sinistral) (ehrenberg 1861) polar research 2014. # 2014 t. pados & r.f. spielhagen. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/22483/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/22483/0 http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 and subpolar turborotalita quinqueloba (natland 1938). the abundance ratio of these two species varies with the hydrographical regime but they both occur in the upper 500 m of the water column, with highest abundances at the sea-ice margin. in this paper, we present new data on the vertical and horizontal distribution of planktic foraminifera species, collected during the polarstern arkxxvi/1 cruise, in 2011, at 10 stations along a transect at 78850?n across fram strait (fig. 1). the samples were taken using a multinet sampler with nets of 63 mm mesh size at five depth intervals. additionally, the sediment surface at the same locations was sampled. in this area, the production maximum of planktic foraminifera usually occurs in mid-summer (kohfeld et al. 1996; jonkers et al. 2010). foraminifer assemblages in core-top and down core samples from fram strait are therefore thought to represent modern and past summer conditions, respectively. in order to examine whether processes during deposition (e.g., lateral transport, selective dissolution) significantly change the distribution of planktic foraminiferal tests in sediments, our multinet sampling results are also compared to the planktic foraminifer assemblages found on the sea floor. oceanography fram strait is characterized by high oceanographic variability. two major surface current systems dominate the area: the west spitsbergen current (wsc) in the eastern part that transports water masses northward and the southward flowing east greenland current (egc) in the west (johannessen 1986). the upper 500 m of the wsc is dominated by atlantic water with a thin (b5 m) mixed layer on top in the summer, resulting from ice melting. in winter, the polar surface water takes over its place and forms a thicker wedge to the west (rudels et al. 1999). the atlantic layer is characterized by salinities above 34.5 and temperatures higher than 0.58c. it ranges between 200 and 500 m. the polar mixed layer (pml) is colder, with a low salinity (b34) and about 50 m thickness. the two layers are isolated by a cold halocline (jones 2001). the egc carries cold, low-saline arctic outflow waters in the upper 200 m. as a result of ice melt, surface waters at the east greenland continental slope are characterized by extremely low salinities in summer (below 32). the pml here is located above a well-developed halocline (rudels et al. 2000). underneath the halocline, warmer and saline waters of atlantic origin can be found. the sea-ice extent in the strait is controlled by the interaction between polar and atlantic waters and is highly variable (vinje 1977, 2001): usually only the shelf of east greenland and the northern fram strait stay covered by ice in the summer, but in the case of extremely cold winter/spring periods the ice can even intrude into the eastern part of the strait (dickson et al. 2000). oceanographic measurements during ark-xxvi/1 cruise (beszczynska-möller & wisotzki 2012) provided fig. 1 absolute abundances of planktic foraminifera at 10 stations along a transect at 78850?n across fram strait. arrows*red for the west spitsbergen current and white for the east greenland current*indicate the ocean circulation in the study area. the white dashed line shows the position of the sea-ice margin in the transect during the sampling period (shipboard observation and satellite data from the us national oceanic and atmospheric administration). map source: the international bathymetric chart of the arctic ocean (jakobsson et al. 2012). recent planktic foraminifera in fram strait t. pados & r.f. spielhagen 2 (page number not for citation purpose) citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 a detailed profile across fram strait at the time of sampling (fig. 2). the atlantic layer in the east was characterized by salinities near 35 and temperatures between 7 and 28c, while the polar layer in the western part of the strait yielded salinities around 33 and a mean temperature of �1.58c. here, on the surface beszczynskamöller & wisotzki (2012) found the above-mentioned low-salinity layer with lowest values of 30.6. underneath the arctic-derived and mainly ice-covered water mass, submerged warm and salty atlantic waters can be found. the sea-ice margin in the transect was located at ca. 28w during the sampling period. material and methods samples used in this study were obtained during the ark-xxvi/1 expedition with the research vessel polarstern in late june/early july 2011 in fram strait. plankton samples were collected by a multinet sampler (net opening 0.5 m 2 ; hydro-bios, kiel, germany) at 10 stations along a transect at 78850?n across fram strait (fig. 1, table 1). the nets of 63 mm mesh size were towed vertically on regular depth intervals (500�300 m, 300�200 m, 200�100 m, 100�50 m, 50�0 m) with a maximum winch speed of 0.3 m/s. during the sampling, the volume of filtered water was measured with a flow metre attached to the multinet frame. the flow metre was discovered to be defective and could not be repaired during the cruise. for some multinet casts and depth intervals, the instrument gave no or obviously unreliable results. we have therefore decided to omit the flow metre data for this study. the filtered volume was calculated from the mouth opening of the multinet and the vertical length of the towed interval for each sample. the plankton samples were sieved with a sieve of 500 mm mesh size, fixed with ethanol and stored at 48c on board. before picking the foraminifera by a pipette, all samples were rinsed with distilled water, treated with hydrogen peroxide to remove organic material and preserved in seawater. the picked specimens were rinsed with distilled water, dried on air and ashed in a low temperature vacuum asher for 90 min. sediment surface samples were obtained from multicorer deployments at the same stations and preserved in ethanol. samples were freeze-dried, wet-sieved with distilled water through a 63 mm mesh, dried at 408c and split into several fractions. all foraminifera from a split of the 100�250 mm fraction of the plankton samples (half or quarter) and from a split of the 100�250 mm fraction of the sediment surface samples (containing �300 individuals) were identified using the taxonomy of hemleben et al. (1989) and counted under dry conditions. temperature and salinity of the water column were measured by a fig. 2 temperature and salinity of the water column in the upper 1000 m along a transect at 78850?n across fram strait. data obtained by conductivity�temperature�density measurements during the ark xxvi/1 expedition (beszczynska-möller & wisotzki 2012). t. pados & r.f. spielhagen recent planktic foraminifera in fram strait citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 conductivity�temperature�depth (ctd) profiler (beszczynskamöller & wisotzki 2012) immediately before the plankton tows. data of ice coverage were obtained by shipboard observations. results planktic foraminifera in the plankton samples the absolute abundances of planktic foraminifera of the 100�250 mm size class in the upper 500 m of the water column show a general increase from ca. 10 individuals per cubic metre (ind./m 3 ) at the eastern stations to 29 ind./m 3 at the sea-ice margin (station 54). further westward we can see a drastic decrease (3 and 9 ind./m 3 , stations 75 and 71, respectively; fig. 1). the species assemblage is dominated by polar neogloboquadrina pachyderma (sin.) and subpolar turborotalita quinqueloba, with proportions of around 76 and 15% in the east and 90 and 5% in the west, respectively. other planktic foraminifera species found in the samples (n. pachyderma [dex.] and globigerina bulloides) contribute less than 9% to the faunal composition. the relative abundance of n. pachyderma (sin.) varies between 73 and 92% with an increasing trend towards the west, while t. quinqueloba shows a reverse tendency with the highest value of 23% in the eastern part of the strait and the lowest (5%) at the greenland slope. figure 3 shows the species composition at the stations in preselected depth intervals. n. pachyderma (sin.) contributes less than 70% to the total planktic foraminiferal fauna at two stations (at 88e and 68e), between 0 and 50 m water depth. the highest proportion of this species was found at station 75 (48w). the two dominant species, n. pachyderma (sin.) and t. quinqueloba, show similar trends in the depth distribution: both have maximum absolute abundances (ind./m 3 ) between 0 and 100 m water depths (fig. 4). n. pachyderma (sin.) has highest abundances near the surface between 0 and 50 m at stations 35 and 87 in the middle of the strait (48e and 38e, respectively) and under the ice cover at station 75. highest amounts of t. quinqueloba in the upper 50 m were found at stations 127, 35 and 44 (88e, 48e and 08e, respectively); at the remaining stations, the depth of 50�100 m yielded maximum abundances of this species. looking at the relative abundances (percentage of total population of the given species at the given station per depth interval; fig. 4), both species show a trend to increasing percentages from the surface to the interval 50�100 m, followed by a decrease to 300�500 m. only at the easternmost station (127), the population maximum of n. pachyderma (sin.) descends below 200 m, while the highest relative abundance of t. quinqueloba at all stations lies above 200 m. sediment samples the samples do not show any evidence of selective carbonate dissolution. only few broken shells were found, and the two studied species do not show any significant difference in the degree of fragmentation. in the absolute abundances of planktic foraminifera, we see a trend similar to that of the plankton samples: the station close to svalbard (25) has a low value (b400 ind./g sediment), followed by a minor peak at 48e (ca. 6500 ind./g). after a steady interval (ca. 3000 ind./g), a significant peak can be observed at the sea-ice margin (station 54, ca. 26 000 ind./g), followed by a drastic decrease to ca. 50 ind./g below the sea ice (fig. 5). neogloboquadrina pachyderma (sin.) has highest proportions in the assemblage at the sea-ice margin (91%) and lowest (73%) in the east (78e, station 25). between these two stations, a steady increase can be detected. t. quinqueloba shows an exactly reverse trend with abundances between 8 and 24% (fig. 6). comparing the relative abundances of n. pachyderma (sin.) and t. quinqueloba on table 1 list of the stations sampled during the arkxxvi/1 cruise with the polarstern in june/july 2011. station no. latitude longitude water depth date ice cover ps78-19 78849.84?n 680.69?e 2464 m 25.06.11 no ps78-25 78849.962?n 780.077?e 1465 m 26.06.11 no ps78-35 78849.772?n 3858.380?e 2335 m 28.06.11 no ps78-39 78850.09?n 1854.56?e 2554 m 28.06.11 no ps78-44 78849.972?n 084.630?e 2636 m 29.06.11 no ps78-54 78850.02?n 280.21?w 2714 m 01.07.11 ice margin ps78-71 78849.66?n 5820.99?w 684 m 04.07.11 ice covered ps78-75 78849.74?n 3855.44?w 1978 m 04.07.11 ice covered ps78-87 78850.44?n 380.19?e 2454 m 06.07.11 no ps78-127 78849.84?n 881.33?e 1019 m 10.07.11 no recent planktic foraminifera in fram strait t. pados & r.f. spielhagen 4 (page number not for citation purpose) citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 fig. 3 faunal composition of samples taken from the upper 500 m of the water column along a transect at 78850?n in fram strait. t. pados & r.f. spielhagen recent planktic foraminifera in fram strait citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 the sediment surface to those counted in the upper 100 m of the water column, the species composition in the depth interval of 50�100 m follows the trend of the core-top samples more precisely than the depth interval between 0 and 50 m mirrors the sediment surface (fig. 6). all count data can be found in supplementary tables s1�s3. discussion species assemblage the planktic foraminiferal species composition of the study area resembles the typical foraminiferal fauna previously reported from arctic/sub-arctic regions with fig. 4 absolute (blue lines) and relative (black bars) abundances (percentage of total population of the given species at the given station per depth interval) of neogloboquadrina pachyderma (sin.) and turborotalita quinqueloba in the upper 500 m along a transect at 78850?n in fram strait. recent planktic foraminifera in fram strait t. pados & r.f. spielhagen 6 (page number not for citation purpose) citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 http://www.polarresearch.net/index.php/polar/rt/suppfiles/22483/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/22483/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/22483/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/22483/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/22483/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/22483/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/22483/0 http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 the clear dominance of neogloboquadrina pachyderma (sin.) and turborotalita quinqueloba. a similar species distribution has been already shown for the arctic ocean (bé 1960; carstens & wefer 1992) and for fram strait (carstens et al. 1997; volkmann 2000). furthermore, despite the warming of atlantic waters passing through the strait (spielhagen et al. 2011), the polar species n. pachyderma (sin.) still clearly prevails in our samples, compared to the subpolar t. quinqueloba. interestingly, at the sampled stations, t. quinqueloba showed relatively low values compared to the results of the above-mentioned studies (fig. 3). carstens et al. (1997) observed a range from 15 to 64% for this species, while the proportion of t. quinqueloba in certain samples collected by volkmann (2000) in warm, atlantic water-dominated regimes reached even 93%. in our plankton samples, the relative abundance of t. quinqueloba varied between 5 and 23% and the sediment surface samples showed a very similar trend. these discrepancies point to a variable foraminiferal production found due to different sampling periods. carstens et al. (1997) and volkmann (2000) took their samples in august, while our samples were collected in late june/early july and therefore probably reflect an early summer plankton bloom. in the eastern north atlantic ocean, schiebel & hemleben (2000) found distinctly different planktic foraminiferal faunas in june and in august. in contrast to early summer, the late summer assemblage was dominated by species preferring warmer waters than other species present, just like the subpolar t. quinqueloba in the planktic foraminiferal fauna of fram strait. it has been shown for the western north atlantic that, while the production of n. pachyderma (sin.) has two peaks during the season and one already in early summer, the production of t. quinqueloba reaches its maximum only in early autumn, after the second bloom of n. pachyderma (sin.) (jonkers et al. 2010). although sediment trap studies in the northeast water polynya revealed a unimodal pattern of planktic foraminiferal production (kohfeld et al. 1996), our data indicate that a temporal offset in the production maxima of the two species exists also at these northern latitudes. this could lead to the relatively low numbers of t. quinqueloba in our samples, collected in june/july compared to the studies conducted in august. horizontal distribution the variable species composition along the transect reflects the complex hydrography of fram strait. in the east, the wsc carries warm, saline atlantic water northwards. in this area, the subpolar t. quinqueloba had higher abundances and the polar n. pachyderma (sin.) had lower abundances than in the western part where the upper 200 m of the egc consist of cold, low-saline arctic outflow waters. here, n. pachyderma (sin.) had a proportion of around 90%. this indicates that the horizontal distribution of the two species is primarily controlled by the distribution of different water masses. the ratio between absolute abundances of planktic foraminifera in the open ocean, at the ice margin and in the ice-covered ocean was found to be ca. 2:4:1 (fig. 1). our data show a similar trend to that in the study of carstens et al. (1997). the ice margin offers increased food supply for the foraminifera with higher primary production caused by diatoms that are the major food fig. 5 absolute abundances of planktic foraminifera on the sediment surface at 10 stations along a transect at 78850?n across fram strait. the sample from station ps78-127 (88e) did not hold enough individuals for counting. fig. 6 comparison of relative abundances of neogloboquadrina pachyderma (sin.) and turborotalita quinqueloba in the depth intervals 0�50 m and 50�100 m as well as on the sediment surface at 10 stations along a transect at 78850?n in fram strait. t. pados & r.f. spielhagen recent planktic foraminifera in fram strait citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 source for n. pachyderma (sin.) (hemleben et al. 1989). diatoms typically do not develop well under permanent ice cover due to the light limitation, but they prefer seasonally stratified water conditions that occur in the marginal ice zone (smith et al. 1987; williams 1993). ice melting increases stratification and consequently the stability of the water column, which triggers phytoplankton blooms (alexander 1980), and the enhanced phytoplankton biomass along the ice margin may have led to a major increase in absolute abundances of planktic foraminifera. vertical distribution both n. pachyderma (sin.) and t. quinqueloba had maximum absolute abundances between 0 and 100 m water depth. however, the relative abundances per depth interval (fig. 4) showed that in the western fram strait, at the ice-covered stations more specimens of n. pachyderma (sin.) lived close to the surface (above 100 m), while in the eastern part of the strait the majority of the population was found deeper, between 50 and 200 m. simstich et al. (2003) analysed plankton and several core-top samples from the nordic seas, taken mainly south of our transect (808n�628n). they reported on a shallow apparent calcification depth in t. quinqueloba over most of the studied profile. if we assume that foraminifera calcify in the water depth where they are most abundant, these results are consistent with our findings. in their study, going from west to the east, the habitat of n. pachyderma (sin.) seems to sink deeper in the atlantic water off norway, similar to what we observe from our samples taken from the warm and saline wsc. these results contrast with the findings of carstens et al. (1997), who concluded that n. pachyderma (sin.) and t. quinqueloba follow the path of the atlantic water submerging below polar water and therefore live deeper in the western part of the strait. during our sampling period, in the western fram strait, the surface polar water masses extended down to 200 m. as none of the studies on planktic foraminifera conducted in the same area (including the study of carstens et al. 1997) revealed an average depth habitat below 200 m, the scenario described by carstens et al. (1997) seems rather unlikely here. furthermore, previous investigations revealed that food availability strongly affects the distribution of planktic foraminifera (schiebel & hemleben 2005). thus, the depth habitat of these protozoa might be controlled by the position of the chlorophyll a maximum (fairbanks & wiebe 1980; kohfeld et al. 1996) rather than by the water mass distribution. from the summer months in the northeast water polynya, with oceanographic conditions similar to the western fram strait, kohfeld et al. (1996) reported maximum chlorophyll a concentrations and consequently highest abundances of n. pachyderma (sin.) between 20 and 80 m water depth, which accords with the results presented here. hirche et al. (1991) also found, for the same period of the year in fram strait, chlorophyll a maxima in the open ocean at greater depth than under the ice coverage. assuming that the depth distribution of n. pachyderma (sin.) is indeed predominantly controlled by food availability in this area, the deeper depth habitat reported by carstens et al. (1997) could be explained by different sampling periods. it is possible that during the above-mentioned experiments in late summer, the ice coverage was not as intact as in june/july and consequently, due to the higher translucency, the deep chlorophyll maximum might have fig. 7 the position of the isopycnal layer of 27.7�27.85 along the transect at 78850?n across fram strait and relative abundance of neogloboquadrina pachyderma (sin.) found in the depth intervals including the density range of 27.7�27.8 (green numbers at the top) and the range of 27.7�27.85 (red numbers at the bottom) at the 10 stations. water density data obtained by conductivity�temperature�density measurements during the ark xxvi/1 expedition (beszczynska-möller & wisotzki 2012). recent planktic foraminifera in fram strait t. pados & r.f. spielhagen 8 (page number not for citation purpose) citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 descended/extended to deeper layers. planktic foraminifera respond to the redistribution of chlorophyll within several days (schiebel et al. 2001) and may therefore have followed the descent of the chlorophyll maximum. another possible explanation for the different findings might be the sampling in different ontogenetic stages. n. pachyderma (sin.) and t. quinqueloba are known to reproduce on a synodic lunar cycle (bijma et al. 1990; schiebel & hemleben 2005) and for reproduction they simultaneously descend from their average depth habitat, possibly to the greatest depth they inhabit during their ontogenetic cycle (berberich 1996; schiebel & hemleben 2005). volkmann (2000) also assumed that n. pachyderma (sin.) prefers shallower water depths under permanent ice coverage. in her study, this species showed maximum abundances in the narrow temperature layer between �1.5 and �1.88c, while t. quinqueloba did not show such preference to a particular temperature range. in our study, the maximum abundances of n. pachyderma (sin.) and t. quinqueloba were found between 0 and 100 m water depth at every station and therefore in a very wide temperature range (from �1.7 to 78c; fig. 2). we therefore assume that the depth habitat of planktic foraminifera in fram strait during june/july is more influenced by the distribution of the food source than by temperature. kozdon et al. (2009) proposed that the average depth habitat of n. pachyderma (sin.) in the nordic seas is controlled by water density and that this species is bound to a layer between 27.7 and 27.8 (potential density, st). along our studied transect during the sampling period, this isopycnal layer was found mainly between 0 and 100 m water depth. there are two exceptions. the first are the stations at 88e, 78e and 48e, where this water mass reaches deeper. the second is the western part of the strait (west of ca. 38w), on the greenland shelf, where the whole layer submerged below 150 m. regarding the relative abundances of n. pachyderma (sin.), our data show that in the eastern and central fram strait (28w�88e) during the sampling period a broad range from 34 to 81% of the population lived in the depth intervals including the specific density range. extending the range to 27.85, we found a better correlation with values between 65 and 86% (fig. 7). in contrast, in the west, in the cold and fresh water masses of the egc, the depth habitat of n. pachyderma (sin.) was found in significantly shallower water depths than the layer of st �27.7�27.8. this discrepancy of findings may be related to the nature of the samples and data used. while the water mass and foraminifer data of our study are from just a short time interval and may be representative of only one early summer plankton bloom, they are nonetheless consistent in being obtained at the same time and place (i.e., station and water depth). kozdon et al. (2009) calculated the calcification depth of n. pachyderma (sin.) using a long-term oceanographic database and temperatures obtained from paired mg/ca and d44/40ca measurements of shells picked from sediment surface samples. such samples integrate foraminifer assemblages over the entire plankton growth seasons in a certain number of years, depending on sedimentation rates and bioturbation intensity. furthermore, variable ages of the surface samples analysed (modern to more than 1000 yr ago; see simstich et al. 2003) may play a more significant role than anticipated by kozdon et al. (2009), who claimed that the samples ‘‘represent modern oceanographic conditions.’’ recent work in the norwegian sea and fram strait (sejrup et al. 2010; spielhagen et al. 2011; werner et al. 2011) has demonstrated that temperature variations of 28c and more occurred in the atlantic water layer during the last one to two millennia. particularly in areas with low sedimentation rates (i.e., in ice-covered regions), sediment surface samples may thus rather represent earlier and colder periods (e.g., the little ice age) than just modern, warmer conditions of the comparatively short industrial period. for this reason, the isopycnals calculated by kozdon et al. (2009) on the basis of data extracted from a hydrographic database may not always correspond to the average conditions during deposition of the related sediment surface samples. our comparison of in situ sampled foraminifera and measurements avoid such potential bias and indicates a wider density range for the habitat of n. pachyderma (sin.). comparison with the sedimentary records comparison of plankton tow results with those from the sediment surface has important implications for palaeoceanographic reconstructions because in such studies core-top samples are usually assumed to represent the recent foraminiferal fauna and therefore modern conditions. in our study area, the planktic foraminiferal species composition in the overlying water column is fairly well reflected in the sediment surface samples: the polar n. pachyderma (sin.) clearly dominates all the samples, with relative abundances of the subpolar t. quinqueloba varying between 8 and 24%. again, the differences between plankton tow and sediment data can most likely be ascribed to the early summer sampling of the water column. lateral advection of foraminifera is not considered a major factor because mean transport distances in fram strait are only 25�50 km for n. pachyderma (sin.) and 50�100 km for t. quinqueloba, as determined for a sediment trap at 1125 m water depth (von gyldenfeldt t. pados & r.f. spielhagen recent planktic foraminifera in fram strait citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 et al. 2000). in the east and the west of the study area (where differences between plankton tow and sediment data are largest), the flow direction of warm and cold water masses is largely normal to the sampling transect and transport effects of subpolar and polar species on the species assemblages on the sea floor can be expected to be minor. furthermore, the increase in abundances in the water column at the sea-ice margin compared to the open ocean and under the ice cover is also seen on the sediment surface (fig. 5). comparison of the relative abundances of n. pachyderma (sin.) and t. quinqueloba in the depth intervals of 0�50 m and 50�100 m to those from the sediment surface (fig. 6) suggests that the sediment surface samples relate best to the fauna living between 50 and 100 m water depth. this hypothesis is supported by the fact that in the water column at almost all stations both species were most abundant in this depth interval. the congruence of the fauna found in the water column and on the sediment surface indicates that in this area processes that can influence the deposition of shells (e.g., lateral transport, selective dissolution) do not change significantly the distribution during settling. since fram strait is relatively narrow and interannual west�east variability in the position of the average summer sea-ice margin can be high, effects of fluctuations related to centennial-scale climate changes may be more subdued in the sediment surface samples than in the nordic seas. as a consequence, the largescale oceanic regimes are more obvious from the faunal compositions. this suggests that planktic foraminifera in fram strait sediments provide a fairly reliable proxy for palaeo-water mass characterization. conclusions in fram strait, the distribution pattern of the two dominating species, neogloboquadrina pachyderma (sin.) and turborotalita quinqueloba shows a distinct relation to the complex hydrography. warm and saline atlantic waters yield higher abundances of the subpolar t. quinqueloba than the cold and fresh waters of the egc, while the polar n. pachyderma (sin.) shows an exactly reverse tendency. the ratio between absolute abundances of planktic foraminifera in the open ocean, at the ice margin and in the ice-covered ocean is ca. 2:4:1. high abundances in the marginal ice zone are related to the high primary production triggered by the strongly stratified water column at the ice margin. the depth habitats of n. pachyderma (sin.) and t. quinqueloba in the area seem predominantly controlled by the availability of food. both species dwell shallower under the ice cover than under ice-free conditions, possibly following the position of the deep chlorophyll maximum. the effect of other water column properties, like temperature, on the depth habitat seems to be masked. we could not verify the hypothesis of kozdon et al. (2009), which associates the vertical distribution of n. pachyderma (sin.) to a discrete isopycnal band. this discrepancy might be due to various factors, for example, differences in applied methods and palaeoceanographic variability in the study area in the recent past. sediment surface samples, often used for palaeoceanographic reconstructions, fairly well reflect the composition of the foraminiferal fauna living in the overlying water column. in fram strait, the species composition and relative abundance in the sediments correlate best with that of the fauna living between 50 and 100 m water depth. in this area*and probably beyond*planktic foraminifera may therefore be used as proxies for subsurface water conditions. acknowledgements the authors wish to thank the captain and crew of the rv polarstern and the alfred wegener institute, helmholtz centre for polar and marine research in bremerhaven for support during ark xxvi/1 cruise. we are indebted to dr angelina kraft for assisting in the deployments of the multinet sampler and to maciej telesinski for collecting the sediment surface samples for this study. dr agnieszka beszczynska-möller and andreas wisotzki provided the ctd data for this study. thanks are due to dr hartmut schulz for kindly providing the low temperature vacuum asher at the university of tübingen and for his hospitality and technical assistance during the process. thanks also go to dr dorothea bauch, who helped during the preparation phase for the cruise and for her valuable comments and suggestions throughout the study, and to dr daniele de corte for reviewing the manuscript. we thank thomas m. cronin and one anonymous reviewer for their constructive feedback and insightful comments. this research was conducted with funding of the european community’s 7th framework programme fp7 2007/2013, marie-curie actions, under grant agreement no. 238111�case itn. rfs thanks the academy of sciences, humanities and literature mainz for financial support through the akademienprogramm. references alexander v. 1980. interrelationships between the seasonal sea ice and biological regimes. cold regions science and technology 2, 157�178. recent planktic foraminifera in fram strait t. pados & r.f. spielhagen 10 (page number not for citation purpose) citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 andrijanic s. 1988. geographical distribution of living planktonic foraminifera (protozoa) off the east coast of australia. australian journal of marine and freshwater research 39, 71�85. bé a.w.h. 1960. some observations on arctic planktonic foraminifera. contributions from the cushman foundation for foraminiferal research 11, 64�68. bé a.w.h. & hutson w.h. 1977. ecology of planktonic foraminifera and biogeographic patterns of live and fossil assemblages in the indian ocean. micropaleontology 23, 369�414. berberich d. 1996. die planktische foraminifere neogloboquadrina pachyderma (ehrenberg) im weddellmeer, antarktis. (the planktic foraminifer neogloboquadrina pachyderma (ehrenberg) in the weddell sea, antarctica.) berichte zur polarforschung 195. bremerhaven: alfred wegener institute. beszczynska-möller a. & wisotzki a. 2012. physical oceanography during polarstern cruise arkxxvi/1. bremerhaven: helmholtz centre for polar and marine research, alfred wegener institute. bijma j., erez j. & hemleben c. 1990. lunar and semi-lunar reproductive cycles in some spinose planktonic foraminifers. journal of foraminiferal research 20, 117�127. carstens j., hebbeln d. & wefer g. 1997. distribution of planktic foraminifera at the ice margin in the arctic (fram strait). marine micropaleontology 29, 257�269. carstens j. & wefer g. 1992. recent distribution of planktonic foraminifera in the nansen basin, arctic ocean. deep-sea research part i 39, 507�524. dickson r.r., osborn t.j., hurrell j.w., meincke j., blindheim j., adlandsvik b., vinje t., alekseev g. & maslowski w. 2000. the arctic ocean response to the north atlantic oscillation. journal of climate 13, 2671�2696. ehrenberg c.g. 1861. über die tiefgrund-verhältnisse des oceans am eingange der davisstrasse und bei island. (about sea bottom conditions at the mouth of davis strait and at iceland.) monatsbericht der königlichen preussischen akademie der wissenschaften zu berlin. pp. 275�315. fairbanks r.g. & wiebe p.h. 1980. foraminifera and chlorophyll maximum: vertical distribution, seasonal succession, and palaeoceanographic significance. science 209, 1524�1525. hansen a. & knudsen k.l. 1995. recent foraminiferal distribution in freemansundet and early holocene stratigraphy on edgeøya, svalbard. polar research 14, 215�238. hemleben c., spindler m. & anderson o.r. 1989. modern planktonic foraminifera. new york: springer. hirche h.-j., baumann m.e.m., kattner g. & gradinger r. 1991. plankton distribution and the impact of copepod grazing on primary production in fram strait, greenland sea. journal of marine systems 2, 477�494. jakobsson m., mayer l., coakley b., dowdeswell j.a., forbes s., fridman b., hodnesdal h., noormets r., pedersen r., rebesco m., schenke h.w., zarayskaya y., accettella d., armstrong a., anderson r.m., bienhoff p., camerlenghi a., church i., edwards m., gardner j.v., hall j.k., hell b., hestvik o., kristoffersen y., marcussen c., mohammad r., mosher d., nghiem s.v., pedrosa m.t., travaglini p.g. & weatherall p. 2012. the international bathymetric chart of the arctic ocean (ibcao) version 3.0. geophysical research letters 39, l12609, doi: 10.1029/2012gl052219. johannessen o.m. 1986. brief overview of the physical oceanography. in b.g. hurdle (ed.): the nordic seas. pp. 103�127. springer: new york. jones e.p. 2001. circulation in the arctic ocean. polar research 20, 139�146. jonkers l., brummer g.-j.a., peeters f.j.c., van aken h.m. & de jong m.f. 2010. seasonal stratification, shell flux, and oxygen isotope dynamics of left-coiling n. pachyderma (sin.) and t. quinqueloba in the western subpolar north atlantic. paleoceanography 25, pa2204, doi: 10.1029/2009pa001849. kohfeld k.e., fairbanks r.g., smith s.l. & walsh i.d. 1996. neogloboquadrina pachyderma (sinistral coiling) as palaeoceanographic tracers in polar oceans: evidence from northeast water polynya plankton tows, sediment traps, and surface sediments. paleoceanography 11, 679�699. kozdon r., eisenhauer a., weinelt m., meland m.y. & nürnberg d. 2009. reassessing mg/ca temperature calibrations of neogloboquadrina pachyderma (sinistral) using paired ca and mg/ca measurements. geochemistry, geophysics, geosystems 10, q03005, doi: 10.1029/2008gc002169. kuroyanagi a. & kawahata h. 2004. vertical distribution of living planktonic foraminifera in the seas around japan. marine micropaleontology 53, 173�196. naomi t.s., mathew k.j. & antony g. 1990. studies on the distribution of recent planktonic foraminifera in the arabian sea and the bay of bengal. in k.j. mathew (ed.): proceedings of the first workshop on scientific results of forv sagar sampada, cochin, 5�7 june 1989. pp. 71�79. cochin, india: central marine fisheries research institute. natland m.l. 1938. new species of foraminifera from off the west coast of north america and from the later tertiary of the los angeles basin. scripps institute of oceanography bulletin 4, 137�164. rudels b., friedrich h.j. & quadfasel d. 1999. the arctic circumpolar boundary current. deep-sea research part ii 46, 1023�1062. rudels b., meyer r., fahrbach e., ivanov v.v., østerhus s., quadfasel d., schauer u., tverberg v. & woodgate r.a. 2000. water mass distribution in fram strait and over the yermak plateau in summer 1997. annales geophysicae 18, 687�705. schiebel r. & hemleben c. 2000. interannual variability of planktic foraminiferal populations and test flux in the eastern north atlantic ocean (jgofs). deep-sea research part ii 47, 1809�1852. schiebel r. & hemleben c. 2005. modern planktic foraminifera. paläontologische zeitschrift 79, 135�148. schiebel r., waniek j., bork m. & hemleben c. 2001. planktic foraminiferal production stimulated by chlorophyll redistribution and entrainment of nutrients. deep-sea research part i 48, 721�740. sejrup h.p., lehman s.j., haflidason h., noone d., muscheler r., berstad i.m. & andrews j.t. 2010. response of t. pados & r.f. spielhagen recent planktic foraminifera in fram strait citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 norwegian sea temperature to solar forcing since 1000 a.d. journal of geophysical research*oceans 115, c12034, doi: 10.1029/2010jc006264. simstich j., sarnthein m. & erlenkeuser h. 2003. paired d18o signals of neogloboquadrina pachyderma (s) and turborotalita quinqueloba show thermal stratification structure in the nordic seas. marine micropaleontology 48, 107�125. smith w.o., jr., baumann m.e.m., wilson d.l. & aletsee l. 1987. phytoplankton biomass and productivity in the marginal ice zone of the fram strait during summer 1984. journal of geophysical research*oceans 92, 6777�6786. spielhagen r.f., werner k., sorensen s.a., zamelczyk k., kandiano e., budeus g., husum k., marchitto t.m. & hald m. 2011. enhanced modern heat transfer to the arctic by warm atlantic water. science 331, 450�453. vinje t. 2001. fram strait ice fluxes and atmospheric circulation: 1950�2000. journal of climate 14, 3508�3517. vinje t.e. 1977. sea ice conditions in the european sector of the marginal seas of the arctic, 1966�75. norsk polarinstitutt årbok 1975, 163�174. volkmann r. 2000. planktic foraminifers in the outer laptev sea and the fram strait*modern distribution and ecology. journal of foraminiferal research 30, 157�176. von gyldenfeldt a.-b., carstens j. & meincke j. 2000. estimation of the catchment area of a sediment trap by means of current meters and foraminiferal tests. deep-sea research part ii 47, 1701�1717. werner k., spielhagen f.r., bauch d., hass h.c., kandiano e. & zamelczyk k. 2011. atlantic water advection to the eastern fram strait*multiproxy evidence for late holocene variability. paleogeography, paleoclimatology, paleoecology 308, 264�276. williams k.m. 1993. ice sheet and ocean interactions, margin of the east greenland ice sheet (14 ka to present): diatom evidence. paleoceanography 8, 69�83. recent planktic foraminifera in fram strait t. pados & r.f. spielhagen 12 (page number not for citation purpose) citation: polar research 2014, 33, 22483, http://dx.doi.org/10.3402/polar.v33.22483 http://www.polarresearch.net/index.php/polar/article/view/22483 http://dx.doi.org/10.3402/polar.v33.22483 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <feff005500740069006c0069007a006500200065007300740061007300200063006f006e00660069006700750072006100e700f5006500730020007000610072006100200063007200690061007200200064006f00630075006d0065006e0074006f007300200050004400460020006500200065006d0069007400690072002000720065006c0061007400f300720069006f007300200073006f00620072006500200063006f006e0066006f0072006d0069006400610064006500200063006f006d0020006f0020005000440046002f0058002d0033002e0020005000440046002f0058002000e900200075006d0020007000610064007200e3006f002000640061002000490053004f00200070006100720061002000740072006f0063006100200064006500200063006f006e0074006500fa0064006f00200067007200e1006600690063006f002e002000500061007200610020006f00620074006500720020006d00610069007300200069006e0066006f0072006d006100e700f50065007300200073006f00620072006500200063006f006d006f00200063007200690061007200200064006f00630075006d0065006e0074006f0073002000500044004600200065006d00200063006f006e0066006f0072006d0069006400610064006500200063006f006d0020006f0020005000440046002f0058002d0033002c00200063006f006e00730075006c007400650020006f0020004700750069006100200064006f002000550073007500e100720069006f00200064006f0020004100630072006f006200610074002e0020004f007300200064006f00630075006d0065006e0074006f0073002000500044004600200070006f00640065006d0020007300650072002000610062006500720074006f007300200063006f006d0020006f0020004100630072006f006200610074002c002000520065006100640065007200200034002e00300020006500200070006f00730074006500720069006f0072002e> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice doi:10.3402/polar.v33.21425 r e s e a r c h / r e v i e w a r t i c l e assessing the importance of human activities for the establishment of the invasive poa annua in antarctica marco a. molina-montenegro,1 fernando carrasco-urra,2 ian acuña-rodrı́guez,1 rómulo oses,1 cristian torres-dı́az 3 & katarzyna j. chwedorzewska 4 1 centro de estudios avanzados en zonas áridas (ceaza), facultad de ciencias del mar, universidad católica del norte, larrondo 1281, coquimbo, chile 2 departamento de botánica, universidad de concepción, casilla 160-c, concepción 4030000, chile 3 laboratio de genómica y biodiversidad, departamento de ciencias naturales, universidad del bı́o-bı́o, chillán 3780000, chile 4 department of antarctic biology, institute of biochemistry and biophysics, polish academy of sciences, pawińskiego 5a, pl-02-106 warsaw, poland keywords alien species; colobanthus quitensis; deschampsia antarctica; human disturbance; poa annua; tourists. correspondence marco a. molina-montenegro, centro de estudios avanzados en zonas áridas (ceaza), facultad de ciencias del mar, universidad católica del norte, larrondo 1281, coquimbo, chile. e-mail: marco.molina@ceaza.cl abstract because of its harsh environmental conditions and remoteness, antarctica is often considered to be at low risk of plant invasion. however, an increasing number of reports have shown the presence and spread of non-native plants in antarctica; it is therefore important to study which factors control the invasion process in this ecosystem. here, we assessed the role of different human activities on the presence and abundance of the invasive poa annua. in addition, we performed a reciprocal transplant experiment in the field, and a manipulative experiment of germination with p. annua and the natives colobanthus quitensis and deschampsia antarctica, in order to unravel the effects of physical soil disturbance on the establishment and survival of p. annua. we found a positive correlation between abundance of p. annua and level of soil disturbance, and that survival of p. annua was 33% higher in sites with disturbed soil than non-disturbed. finally, we found that disturbance conditions increased germination for p. annua, whereas for native species germination in experimentally disturbed soil was either unchanged or reduced compared to undisturbed soil. our results indicate that human activities that modify abiotic soil characteristics could play an important role in the abundance of this invasive species. if the current patterns of human activities are maintained in antarctica, the establishment success and spread of p. annua could increase, negatively affecting native flora. considered one of the harshest environments worldwide, antarctica is characterized by low temperatures, high solar radiation, strong winds, a short growing season and limited water and nutrient availability (robinson et al. 2003; wasley et al. 2006). antarctica has been considered less susceptible to biological invasions than other ecosystems due to its severe environmental conditions, isolation and exceptionally low species diversity (convey 2003; hughes et al. 2010). nevertheless, a number of studies have documented the presence of alien species in maritime antarctica and on the mainland (lewissmith 1996; frenot et al. 2005; chwedorzewska 2008). many of the alien species reported in these studies are low in abundance and are restricted to disturbed sites (chwedorzewska 2008, 2009; chwedorzewska & korczak 2010; molina-montenegro et al. 2012; cuba-dı́az et al. 2013). the non-native species are mainly found in the vicinity of scientific bases and tourist landing areas, suggesting that their presence and abundance are facilitated by human activities (chwedorzewska & korczak 2010; chown et al. 2012; molina-montenegro et al. 2012). human travel is occurring at an unprecedented level across the globe and is becoming a major vector for the transfer of propagules, such as seeds, eggs and spores, of species alien to the antarctica (e.g., frenot et al. 2005; polar research 2014. # 2014 m.a. molina-montenegro et al. this is an open access article distributed under the terms of the creative commons attributionnoncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 21425, http://dx.doi.org/10.3402/polar.v33.21425 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21425 http://dx.doi.org/10.3402/polar.v33.21425 lityńska-zając et al. 2012). introduction routes of alien organisms are largely associated with the movement of people and cargo from scientific programmes and to a lesser extent tourist operations (frenot et al. 2005; tin et al. 2009; chown et al. 2012; molina-montenegro et al. 2012). all cargo, personal luggage, clothes and equipment of people visiting antarctic stations can be a potentially contaminated by alien propagules. several studies have examined the relationship between the number of alien species established in sub-antarctica and antarctica and the number of human visitors (e.g., chown et al. 1998; lee & chown 2009a, 2009b). in spite of the constant increase in tourist visits mainly in the antarctic peninsula region, in many ways research stations could be considered to have a greater impact on the terrestrial environment. about 40 000 people, mostly tourists, visit the antarctic coast every year, whereas antarctica has a summer population of about 4000 researchers from different countries (frenot et al. 2005; iaato 2013). scientific expeditions remain in one place much longer than tourists, affecting the environment around the station continuously, and bring in large quantities of supplies and equipment (which may be contaminated with soil and propagules). scientific activity is most intense during summer melts, when vegetation is developing and seabirds and mammals are reproducing (e.g., chwedorzewska & korczak 2010; chown et al. 2012). the construction of buildings and other infrastructure at antarctic stations disturbs the soil, physically and chemically, creating areas around each station that could be particularly vulnerable to human impact (chwedorzewska & korczak 2010). keeping stations supplied and maintaining infrastructure require the use of heavy vehicles, typically concentrated in a very limited area, which contributes to potential soil damage. most stations are built in ice-free areas, which have the most favourable microclimates for the establishment of plants in the antarctic. recent reviews have identified several pivotal factors in determining the establishment and spread of non-native invasive species (e.g., richardson et al. 2000; dietz & edwards 2006; theoharides & dukes 2007). for instance, while the native community and abiotic features of the invaded habitat are important barriers for invasion (richardson et al. 2000), disturbance is considered one of the main drivers of plant invasions (hobbs & humphries 1995; londsale 1999). in antarctic habitats, disturbances can be caused by natural geomorphological processes such as landslides, cryogenic soil movement (convey 1996), by deglaciation and by animals, such as seals (scott & kirkpatrick 2005; hausmann et al. 2013). the majority of non-native species reported in the antarctica has been found in disturbed sites surrounding scientific bases (olech 1996; chwedorzewska & korczak 2010; molinamontenegro et al. 2012; cuba-dı́az et al. 2013) or in pioneer zones (olech & chwedorzewska 2011). nevertheless, the establishment of alien vascular plants has recently also been reported in natural habitats (olech & chwedorzewska 2011). one of the most ubiquitous plant species in the world, poa annua is widely established in the sub-antarctic and maritime antarctica (see hughes et al. 2010). the wide distribution of p. annua may result from its dispersal mechanism and physiological tolerance, mainly in areas subject to human activities or in pioneer zones (frenot et al. 1997) and in those with disturbance and manuring from animal aggregations (walton 1975). this alien species is considerate an invasive species in antarctica, with negative impacts on the biomass and physiological performance of native vascular species, with which it competes for resources and/or space (molina-montenegro et al. 2012). in this study we assess different variables related to human activities with the abundance and the successful establishment of the invasive plant species p. annua in the antarctic peninsula, and south shetland islands. we also analyse the survival percentage of p. annua growing in sites with different kinds of soil disturbance. finally, we evaluate the germination percentage of the alien p. annua and the native plants colobanthus quitensis and deschampsia antarctica subjected experimentally to different levels of soil disturbance. materials and methods we visited 25 different sites on antarctic islands and the antarctic peninsula during the chilean scientific antarctic expeditions of 2007/08 and 2009/10*the austral summer seasons*in order to search for populations of poa annua (see molina-montenegro et al. 2012). in each site we visually surveyed the presence of p. annua around every building and point of landing (fig. 1). each plant individual was labelled in order to avoid recording the same individuals twice, and its distance to the closest buildings was recorded. out of all sites visited we found individuals of p. annua at six of them. the plant was recorded at one point at each of five sites, whereas at the polish arctowski antarctic station it was recorded at two points. in order to find potential drivers of p. annua establishment, we performed a regression analysis using the abundance of this species and (i) mean number of tourists landed in each point where p. annua has been recorded, (ii) mean number of scientists and operators landed in each point where p. annua has been recorded, (iii) distance to the main building of each station and (iv) level of soil disturbance. we used the time in years from anthropogenic effects on establishment of poa annua m.a. molina-montenegro et al. 2 (page number not for citation purpose) citation: polar research 2014, 33, 21425, http://dx.doi.org/10.3402/polar.v33.21425 http://www.polarresearch.net/index.php/polar/article/view/21425 http://dx.doi.org/10.3402/polar.v33.21425 the last time when any building was constructed or renovated at each station as a proxy for soil disturbance. drawing from the database of the international association of antarctica tour operators, we considered the mean number of visits (tourists and non-tourists) landed during the 2007/08 and 2009/10 summer seasons*the growing seasons that coincided with our fieldwork. to assess the effect of different soil-patch types on establishment, we performed a transplant experiment with adult individuals of p. annua collected close to the coastline (within 30�40 m to the sea). this experiment was conducted in a study area near arctowski station. all plants used ranged in height from 5 to 7 cm and appeared healthy. each individual plant was excavated together with the soil around the roots (ca. 500 g) and kept wellwatered in a plastic box under natural conditions of light and temperature for 12 h until the transplant. plant status was visually assessed just before the transplant (plants showing foliar and/or root damage were excluded). we considered two soil-patch types for the experiment; the first type was in the bare ground between the resident vegetation (natural) and the second was in the disturbed soil surrounding the scientific stations. we selected three patches by each soil-type, with distances of 23, 41 and 56 m among each pair of sites (natural�disturbed). at each patch, 10 p. annua individuals were planted within each of three soil-patches of each type (n �30 individuals per soil-type). individuals were planted at least 5 cm apart from each other. transplants were carried out during the 2010/11 growing season and seedling survival was evaluated after six weeks. additionally, we compared nitrogen availability and soil moisture between five non-disturbed and five disturbed patches. a soil sample of 10 cm depth (ca. 100 g) was taken in each patch. this depth was selected is this the average depth of the root zone of p. annua in the study. soil samples were stored in sealed plastic bags and sent for analyses to determine the concentration of nitrate (no�3 ; robarge et al. 1983) and ammonium (nh þ 4 ; longeri et al. 1979). soil moisture (soil matric potential) was measured in five non-disturbed patches and five disturbed patches during the mid-growth season (january 2010). at each sampling point, a 2725 series jet fill tensiometer (soil moisture equipment corp., santa barbara, ca, us) was dug into the soil to a depth of 10 cm. tensiometers were placed at mid-day and, after a stabilization period of 2 h, the soil matric potential was recorded. at the end of experiment, all surviving individuals were removed from the site and destroyed. finally, we performed a manipulative experiment to assess the effect of soil disturbance on germination of pou annua, colobanthus quitensis and deschampsia antarctica. we collected seeds from the inflorescence of the previous year’s adult healthy-looking plants growing in tussocks in ice-free zones close to the coastline. at the commencement of this experiment three seeds of each species were tested to assess viability. this was done by cutting the seed in half on the equatorial axis with a razor blade after 24 h of immersion in tetrazolium chloride. all seeds were viable. each experimental unit was a plastic pot (50 �40 �30 cm) filled with soil extracted from the study site. each experimental unit consisted 10 seeds of p. annua or c. quitensis or d. antarctica (n �6 pots per species; total n �18 pots). seeds were buried 4�5 cm deep in a plastic pot, as this was the maximum depth at which p. annua seeds were found at the study site. pots were subjected to a 20/4 h light/dark photoperiod at 48c and were watered with 100 ml of water every four days. to determine the effect of soil disturbance on germination, half the pots of each species was subjected to manual disturbance in the top 4�5 cm of soil every three days until emergence of the first seedling (total n �9 pots). after the first germination, manual disturbance ceased in order to avoid seedling damage, but the recording of germination continued. the remaining pots*the controls*were undisturbed. disturbance was deemed similar in intensity and effects to that of footfall and light vehicle traffic. fig. 1 poa annua individual growing at arctowski station, king george island, south shetland islands, antarctica. (photograph by marco a. molina-montenegro, february 2010). m.a. molina-montenegro et al. anthropogenic effects on establishment of poa annua citation: polar research 2014, 33, 21425, http://dx.doi.org/10.3402/polar.v33.21425 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21425 http://dx.doi.org/10.3402/polar.v33.21425 at the conclusion of the experiment, which ran for three months, we recorded the number of emerged seedlings. statistical analysis to investigate the relationship between the abundance of p. annua individuals and the different human activities in the south shetland islands and the antarctic peninsula, we used standard pearson correlations. a one-way anova was performed to compare the nitrogen content, water availability and survival percentage of p. annua individuals growing in soil patches with different disturbance type. to evaluate the effect of disturbance on the germination percentage in both natives and alien plant species, we conducted a two-way anova. for all two-way anovas, the assumptions of normality and homogeneity of variances were tested using the shapiro� wilks and bartlett tests, respectively (zar 1999). results during the 2007/08 and 2009/10 growing season, the presence and abundance of p. annua at six different sites was recorded out of a total of 25 sites in the south shetland islands (one site at deception island and two sites at arctowski station) and the antarctic peninsula (bernardo o’higgins station, gabriel gonzález videla station, and almirante brown station). regression analysis did not show a relation between p. annua abundance and the mean number of tourists or non-tourists landed at each scientific station (fig. 2a, b). however, the distance of p. annua individuals to the main station building showed a positive but not significant correlation (fig. 2c), and the abundance of p. annua was positively and significantly correlated with the number of years elapsed since any building was constructed or renovated (fig. 2d). in the transplant experiment, the survivorship of p. annua individuals was significantly higher (f1, 8 �6.11; p �0.039) in sites with soil disturbance than without disturbance (fig. 3). soil moisture was not different (f1, 8 �28.52; p �0.09) between disturbed and nondisturbed patches of soil ( �2594 and �3096 mpa disturbed and non-disturbed, respectively). in contrast, the available nitrogen content of the disturbed soil was significantly higher (f1, 8 �231.21; pb0.01) than in nondisturbed conditions (7.5691.2 and 3.9891.6 mg �k�1 disturbed and non-disturbed, respectively). overall, the percentage of germination was significantly increased under the disturbance treatment (f1, 24 �563.33; pb0.001), but this trend was not similar for all species fig. 2 analysis of correlations between abundance of poa annua recorded at different sites and (a) annual mean number of tourists landed, (b) annual mean number of scientists landed, (c) distance to main building of each site, and (d) time in years since last time that a building was built or renovated in each site. we considerate in this analysis all sites containing some p. annua individuals: general bernardo o’higgins station in northern graham land, almirante brown station at paradise bay, gabriel gonzález videla station at paradise bay, two sites at henry arctowski station at king george island, and deception island. anthropogenic effects on establishment of poa annua m.a. molina-montenegro et al. 4 (page number not for citation purpose) citation: polar research 2014, 33, 21425, http://dx.doi.org/10.3402/polar.v33.21425 http://www.polarresearch.net/index.php/polar/article/view/21425 http://dx.doi.org/10.3402/polar.v33.21425 (f2, 24 �364.25; pb0.001). for p. annua the germination increased with disturbance, for c. quitensis germination decreased significantly under disturbance while for d. antarctica the germination percentage was not different between the disturbance and control treatments (fig. 4). discussion in the 21st century, the number of visitors to the antarctica and the scale of human influence have increased dramatically, mainly due to tourism (iaato 2013). there has been concern about the potential impact of visitors on the antarctic environment (culik & wilson 1995; chown et al. 2012). several studies have aimed to detect the effects of this visitor pressure (chwedorzewska & korczak 2010). we did not find a positive correlation between poa annua abundance and the mean number of tourists or scientists visiting the antarctic. however, a positive relationship between the abundance of p. annua and the time since a base underwent construction suggests that this kind of human activity influences the establishment phase of this species. we believe that human activity associated with research stations enhances soil nutrients and modifies the soil matrix, and therefore facilitates the germination and establishment of p. annua. several studies have shown that cargo and vehicles transported to antarctic research stations contain propagules of many plants (whinam et al. 2005; lee & chown 2009b; chown et al. 2012). hughes et al. (2010) highlighted that research station construction also facilitates the transport of non-native seeds. we found that time since construction influences the presence of p. annua, most likely because more time allows for the establishment and population expansion of the plant. in antarctica, ice-free areas near the coast are rather scarce and are hotspots for local fauna and flora (convey 1996) as well as humans (chown et al. 2012). high traffic around research stations creates a high level of soil disturbance, which can facilitate the establishment of exotic plants (chwedorzewska 2008; cuba-dı́az et al. 2013), as our experiments support. in stressful environments such as those found in the antarctic terrestrial ecosystems, it has been predicted that alien species are unlikely to colonize and extend their range of distribution unless some process relaxes the environmental constraints (dullinger et al. 2003; pauchard et al. 2009). it is widely assumed that soil disturbance enhances resource availability (e.g., burke & grime 1996; davis et al. 2000), and some have examined the effect of disturbances in cold environments and shown increased nutrients, or higher accessibility, following disturbance (stanton et al. 1994; grieve 2000). we have elsewhere shown that alien species take advantage of high resource availability (e.g., nutrient or water), improving their ecophysiological performance (molina-montenegro et al. 2011). in the study reported here, we found that disturbed soils had higher levels of nutrients, as well as germination and survival percentage of p. annua, suggesting that disturbance by humans may generate microhabitats more favourable to p. annua than to native plants. alternatively, the enhanced establishment and survival of p. annua in disturbed areas could result from non-random spatial distribution due to wind. in cold environments some plant fig. 4 germination percentage (mean9sd) of the natives colobanthus quitensis and deschampsia antarctica and the alien poa annua subjected to manipulative experiments without and with soil disturbance. asterisks indicate significant differences (a posteriori tukey test a�0.05). fig. 3 survival percentage (mean92ee) of poa annua individuals growing in soil patches without and with disturbance. m.a. molina-montenegro et al. anthropogenic effects on establishment of poa annua citation: polar research 2014, 33, 21425, http://dx.doi.org/10.3402/polar.v33.21425 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21425 http://dx.doi.org/10.3402/polar.v33.21425 species show greater establishment and survival percentages when sheltered from the desiccating effect of wind (resler et al. 2005). in antarctica p. annua has been shown to become established at sites sheltered from wind, such as alongside buildings (olech 1996). more surveys should be conducted to further explain the spatial distribution and performance of p. annua in antarctica. since it was first recorded in the mid-1980s (olech 1996), p. annua is the only introduced plant species to have established permanent scattered populations in the shetland islands and on the antarctic peninsula (frenot et al. 2005; chwedorzewska 2008, 2009; molinamontenegro et al. 2012). the species has shown a steady, constant increase in abundance and number of new populations (molina-montenegro et al. 2012). having spread to alpine ecosystems (johnston & pickering 2001), northern europe (gederaas et al. 2012) and sub-antarctic islands (frenot et al. 2005), p. annua is ‘‘generalist’’ invasive species that tolerates stressful environments and takes advantage of favourable conditions, e.g., enhanced nitrogen availability in disturbed soils. surprisingly, nowadays there is no international policy to control the introduction of non-native species to antarctica. our study provides evidence that antarctic environments could be severely impacted in the near future by such introductions and in the long-term they may have unsuspected consequences on antarctic diversity. although, some efforts have been made to accomplish this goal, they are still insufficient to mitigate the negative impacts of human activities on antarctic biodiversity (see hughes & convey 2014). in summary, p. annua is positively correlated with human activities and its survival and germination is enhanced in soil disturbance conditions. we conclude that human impacts, mainly associated with research activities, may have negative effects on the native species but positively influence the abundance and spread of the invasive p. annua on the antarctic continent. acknowledgements we acknowledge the financial support of the chilean antarctic institute (inach project t-14-08 and g-22-11). references burke m.j.k. & grime j. 1996. an experimental study of plant community invisibility. ecology 77, 776�790. chown s.l., gremmen n.j.m. & gaston k.j. 1998. ecological biogeography of southern islands: species�area relationships, human impacts and conservation. american naturalist 152, 562�575. chown s.l, huiskes a.h.l., gremmenb n.j.m., lee j.e., teraudsa a., crosbie k., frenot y., hughes k.a., imura s., kiefer k., lebouvier m., raymond b., tsujimoto m., ware c., van de vijver b. & bergstrom d.m. 2012. continentwide risk assessment for the establishment of nonindigenous species in antarctica. proceedings of the national academy of science of the united states of america 109, 4938�4943. chwedorzewska k.j. 2008. poa annua l. in antarctic: searching for the resource of introduction. polar biology 31, 263� 268. chwedorzewska k.j. 2009. terrestrial antarctic ecosystem at the changing world*an overview. polish polar research 30, 263�273. chwedorzewska k.j. & korczak m. 2010. human impact upon the environment in the vicinity of arctowski station, king george island, antarctica. polish polar research 31, 45�60. convey p. 1996. the influence of environmental characteristics on life history attributes of antarctic terrestrial biota. biological reviews of the cambridge philosophical society 71, 191�225. convey p. 2003. maritime antarctic climate change: signals from terrestrial biology. antarctic research series 79, 145�158. cuba-dı́az m., troncoso j.m., cordero c., finot v.l. & rondanelli-reyes m. 2013. juncus bufonius, a new nonnative vascular plant in king george island, south shetland islands. antarctic science 25, 385�386. culik b.m. & wilson r.p. 1995. penguins disturbed by tourists. nature 376, 301. davis m.a., grime j.p. & thompson k. 2000. fluctuating resources in plant communities: a general theory of invisibility. journal of ecology 88, 528�534. dietz h. & edwards p.j. 2006. recognition that causal processes change during plant invasion helps explain conflicts in evidence. ecology 87, 1359�1367. dullinger s., dirnböck t. & grabherr c. 2003. patterns of shrub invasion into high mountain grasslands of the northern calcareous alps, austria. arctic, antarctic and alpine research 35, 434�441. frenot y., chown s.l., whinam j., selkirk p.m., convey p., skotnicki m. & bergstrom d.m. 2005. biological invasions in the antarctic: extent, impacts and implications. biological review 80, 45�72. frenot y., gloaguen j.c. & trehen p. 1997. climate change in kergulen islands and colonization of recently deglaciated areas by poa kergulensis and p. annua. in b. battaglia (ed.): antarctic communities: species structure and survival. pp. 358� 366. cambridge: cambridge university press. gederaas l., moen t.l., skjelseth s. & larsen l-k. 2012. alien species in norway*with the norwegian black list. trondheim: norwegian biodiversity information centre. grieve i.c. 2000. effects of human disturbance and cryoturbations on soil iron and organic matter distributions and on carbon storage at high elevations in the cairngorm mountains, scotland. geoderma 95, 1�14. hausmann n.s., rudolph e.m., kalwij j.m. & mcintyred t. 2013. fur seal populations facilitate establishment of exotic vascular plants. biological conservation 162, 33�40. anthropogenic effects on establishment of poa annua m.a. molina-montenegro et al. 6 (page number not for citation purpose) citation: polar research 2014, 33, 21425, http://dx.doi.org/10.3402/polar.v33.21425 http://www.polarresearch.net/index.php/polar/article/view/21425 http://dx.doi.org/10.3402/polar.v33.21425 hobbs r.j. & humphries s.e. 1995. an integrated approach to the ecology and management of plant invasions. conservation biology 9, 761�770. hughes k.a. & convey p. 2014. alien invasions in antarctica*is anyone liable? polar research 33, article no. 22103, doi: 10.3402/polar.v33.22103. hughes k.a., convey p., maslen n.r. & smith r.l.i. 2010. accidental transfer of non-native soil organisms into antarctica on construction vehicles. biological invasions 12, 875�891. iaato (international association of antarctica tour operators) 2013. number of visitors (tourists, staff and crew) per site per vessel*all antarctic sites. accessed on the internet at http://iaato.org/tourism-statistics on 10 march 2013. johnston f.m. & pickering c.m. 2001. alien plants in the australian alps. mountain research and development 21, 284� 291. lee j.e. & chown s.l. 2009a. breaching the dispersal barrier to invasion: quantification and management. ecological applications 19, 1944�1959. lee j.e. & chown s.l. 2009b. quantifying the propagule load associated with the construction of an antarctic research station. antarctic science 21, 471�475. lewis-smith r.i. 1996. introduced plants in antarctica: potential impacts and conservation issues. biological conservation 76, 135�146. lityńska-zając m., chwedorzewska k.j., olech m., korczakabshire m. & augustyniuk-kram a. 2012. diaspores and phyto-remains accidentally transported to the antarctic station during three expeditions. biodiversity and conservation 21, 3411�3421. londsale w.m. 1999. global patterns of plant invasions and the concept of invisibility. ecology 80, 1522�1536. longeri l., etchevers j. & venegas j. 1979. metodologı́a de perfusión para estudios de nitrificación en suelo. (perfusion method for soil nitrification studies.) ciencia e investigación agraria 6, 295�299. molina-montenegro m.a., carrasco-urra f., rodrigo c., convey o., valladares f. & gianoli e. 2012. occurrence of the non-native annual bluegrass on the antarctic mainland and its negative effects on the native plants. conservation biology 26, 717�723. molina-montenegro m.a., quiróz c.l., torres-dı́az c. & atala c. 2011. functional differences in response to drought in the alpine invasive taraxacum officinale from native and introduced habitat ranges. plant ecology and diversity 4, 37�44. olech m. 1996. human impact on terrestrial ecosystem in west antarctica. proceedings of the nipr symposium on polar biology 9, 299�306. olech m. & chwedorzewska k.j. 2011. the first appearance and establishment of an alien vascular plant in natural habitats on the forefield of a retreating glacier in antarctica. antarctic science 23, 153�154. pauchard a., kueffer c., dietz h. & miren consortium. 2009. ain’t no mountain high enough: plant invasions reaching high elevations. frontiers in ecology and environment 7, 479� 486. resler l.m., butler d.r. & malanson g.p. 2005. topographic shelter and conifer establishment and mortality in an alpine environment, glacier national park, montana. physical geography 26, 112�125. richardson d.m., pysek p., rejmánek m., barbour m.g., panetta f.d. & west c.j. 2000. naturalization and invasion of alien plants: concepts and definitions. diversity and distributions 6, 93�107. robarge w.p., edwards a. & johnson b. 1983. water and waste water analysis for nitrate via nitration of salicylic acid. communication in soil science and plant analysis 14, 1207� 1215. robinson s.a., wasley j. & tobin a.k. 2003. living on the edge*plants and global change in continental and maritime antarctica. global change biology 9, 1681�1717. scott j.j. & kirkpatrick j.b. 2005. changes in subantarctic heard island vegetation at sites occupied by poa annua, 1987�2000. arctic, antarctic, and alpine research 37, 366�371. stanton m.l., rejmánek m. & galen c. 1994. changes in vegetation and soil fertility along a predictable snowmelt gradient in the mosquito range, colorado, usa. arctic and alpine research 26, 364�374. theoharides k.a. & dukes j.s. 2007. plant invasions across space and time: factors affecting nonindigenous species success during four stages of invasions. new phytologist 176, 256�273. tin t., fleming z., hughes k.a., ainley d., convey p., moreno c., pfeiffer s., scott j. & snape i. 2009. impacts of local human activities on the antarctic environment: a review. antarctic science 21, 3�33. walton d.w.h. 1975. european weeds and other alien species in the subantarctic. weed research 15, 271�282. wasley j.s., robinson a., lovelock c.e. & popp m. 2006. climate change manipulations show antarctic flora is more strongly affected by elevated nutrients than water. global change biology 12, 1800�1812. whinam j., chilcott n. & bergstrom d.m. 2005. subantarctic hitchhikers: expeditioners as vectors for the introduction of alien organisms. biological conservation 121, 207�221. zar j.h. 1999. biostatistical analysis. 4th edn. new jersey: prentice-hall. m.a. molina-montenegro et al. anthropogenic effects on establishment of poa annua citation: polar research 2014, 33, 21425, http://dx.doi.org/10.3402/polar.v33.21425 7 (page number not for citation purpose) http://iaato.org/tourism-statistics http://www.polarresearch.net/index.php/polar/article/view/21425 http://dx.doi.org/10.3402/polar.v33.21425 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <feff00560065007200770065006e00640065006e0020005300690065002000640069006500730065002000450069006e007300740065006c006c0075006e00670065006e002c00200075006d002000650069006e0065006e00200042006500720069006300680074002000fc00620065007200200064006900650020005000440046002f0058002d0033002d004b006f006d007000610074006900620069006c0069007400e4007400200065007200680061006c00740065006e00200075006e00640020005000440046002d0044006f006b0075006d0065006e007400650020006e00750072002000640061006e006e0020007a0075002000650072007300740065006c006c0065006e002c002000770065006e006e0020007300690065002000fc0062006500720020006400690065007300650020004b006f006d007000610074006900620069006c0069007400e400740020007600650072006600fc00670065006e002e0020005000440046002f00580020006900730074002000650069006e0065002000490053004f002d004e006f0072006d0020007a0075006d002000410075007300740061007500730063006800200076006f006e0020006400690067006900740061006c0065006e00200044007200750063006b0076006f0072006c006100670065006e002e0020005700650069007400650072006500200049006e0066006f0072006d006100740069006f006e0065006e0020007a0075006d002000450072007300740065006c006c0065006e00200076006f006e0020005000440046002f0058002d0033002d006b006f006d00700061007400690062006c0065006e0020005000440046002d0044006f006b0075006d0065006e00740065006e002000660069006e00640065006e002000530069006500200069006d0020004100630072006f006200610074002d00480061006e00640062007500630068002e00200044006900650020005000440046002d0044006f006b0075006d0065006e007400650020006b00f6006e006e0065006e0020006d006900740020004100630072006f0062006100740020006f0064006500720020006d00690074002000640065006d002000520065006100640065007200200034002e003000200075006e00640020006800f600680065007200200067006500f600660066006e00650074002000770065007200640065006e002e> /fra <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> /jpn <feff005000440046002f0058002d00336e9662e0306e30ec30dd30fc30c87528304a30883073658766f84f5c62107528306b4f7f75283057307e30593002005000440046002f00580020306f30b030e930d530a330c330af30b3002030f330c630f330c4590963db306b304a3051308b002000490053004f00206a196e96306730593002005000440046002f0058002d003300206e9662e0306e658766f84f5c6210306b306430443066306f0020004100630072006f006200610074002030e630fc30b630ac30a430c9309253c2716730573066304f30603055304430024f5c62103057305f00200050004400460020306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200034002e003000204ee5964d30678868793a3067304d307e30593002> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <feff0041006e007600e4006e006400200065006e00640061007300740020006400650020006800e4007200200069006e0073007400e4006c006c006e0069006e006700610072006e00610020006e00e40072002000640075002000760069006c006c00200072006100700070006f007200740065007200610020006f006d0020005000440046002f0058002d0033002d007300740061006e00640061007200640020006f0063006800200073006b0061007000610020005000440046002d0064006f006b0075006d0065006e007400200073006f006d0020006600f6006c006a00650072002000640065006e006e00610020007300740061006e0064006100720064002e0020005000440046002f0058002000e4007200200065006e002000490053004f002d007300740061006e00640061007200640020006600f6007200200075007400620079007400650020006100760020006700720061006600690073006b007400200069006e006e0065006800e5006c006c002e0020004d0065007200200069006e0066006f0072006d006100740069006f006e0020006f006d002000680075007200200064007500200073006b00610070006100720020005000440046002d0064006f006b0075006d0065006e007400200073006f006d0020006600f6006c006a006500720020005000440046002f0058002d003300200068006900740074006100720020006400750020006900200061006e007600e4006e00640061007200680061006e00640062006f006b0065006e0020006600f600720020004100630072006f006200610074002e0020005000440046002d0064006f006b0075006d0065006e00740065006e0020006b0061006e002000f600700070006e006100730020006d006500640020004100630072006f0062006100740020006f00630068002000520065006100640065007200200034002e003000200065006c006c00650072002000730065006e006100720065002e> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice larter&nagy.indd 131larter & nagy 2004: polar research 23(2), 131–140 caribou (rangifer tarandus) and muskoxen (ovibos moschatus) are the only ungulate species successfully occupying arctic tundra environments. caribou and muskoxen have different morphological adaptations which presumably enabled them to utilize forage resources with little overlap (klein 1992). caribou, with their small body size, narrow muzzle, small gut capacity, and rapid passage rate (tyler & blix 1990; klein 1992), are representative of a mixed feeder type, intermediate between roughage feeders and concentrate selectors according to hofmann’s (1989, 2000) classifi cation. muskoxen, with their large body size, broad muzzle, and large gut capacity capable of processing large amounts of low quality forage (klein 1992) are representative of roughage feeders (grazers) according to hofmann’s (1989, 2000) classifi cation. a number of studies have reported the diets of muskoxen and caribou in arctic canada (e.g. wilkinson et al. 1976; parker 1978; shank et al. 1978; thomas & edmonds 1983; oakes et al. 1992; larter & nagy 1997), alaska (e.g. svendsen 1992; ihl 1999; ihl & klein 2001), and greenland (thing 1984; thing et al. 1987; klein & bay 1990). many diet studies have shown willow (salix spp.) to be a noticeable component of the muskoxen diet regardless of season (e.g. wilkinson et al. 1976; thing 1984; svendsen 1992; larter & nagy 1997; thomas et al. 1999). in early summer, willow use was prominent among muskoxen on banks island (larter & nagy 1997). willow is also a prominent component of their late winter diet especially in years of deeper and harder snow (larter & nagy 1997; thomas et al. 1999). lichen is an important winter food for barrenground caribou on the mainland, but in the high arctic islands, which support low lichen biomass, caribou must use other forages, usually willow and graminoids (reimers et al. 1980; klein 1992). where food choices are limited or muskox density is high, the two species may compete for food seasonal changes in the composition of the diets of peary caribou and muskoxen on banks island nicholas c. larter & john a. nagy caribou and muskoxen are the only ungulate species occupying arctic tundra environments. we analysed plant fragments found in fresh (< 4 hr old) samples of faecal material to determine the diets of peary caribou (rangifer tarandus pearyi) and muskoxen (ovibos moschatus) on banks island, canada. willow was a major component of the diets of both animals, dominating the caribou diet during summer and representing substantial proportions of the muskoxen diet during at least seven months of the year. the diet of caribou was more diverse than that of muskoxen and was dominated by sedge, willow (salix arctica), legume (astragalus spp., oxytropis spp.) and dryas integrifolia. the diet of muskoxen was dominated by sedge and willow. there was substantial overlap (up to 70 %) in the diets of these herbivores with the similarity more pronounced in areas of high muskox density (ca. 1.65 animals/km2). we discuss herbivore diets in relation to foraging behaviour and forage availability. n. c. larter, government of the northwest territories, department of resources, wildlife & economic development, box 240, ft. simpson, nt, canada x0e 0n0, nic_larter@gov.nt.ca; j. a. nagy, government of the northwest territories, department of resources, wildlife & economic development, bag service #1, inuvik, nt, canada x0e 0t0. 132 seasonal changes in composition of diets of peary caribou and muskoxen (mckendrick 1981). on banks island in the canadian high arctic, lichen biomass is low and the muskox population represents a substantial proportion of worldwide muskoxen numbers, with some of the highest reported densities of muskox, 1.5 2.0 animals/km2 (nagy et al. 1996; larter & nagy 2001a). during the 1990s peary caribou numbers on banks island were at historic lows, 500 1000 animals, excluding calves (nagy et al. 1996). peary caribou rely on willow during the short arctic summers in order to regain fat prior to winter and there was concern that the availability of willow during summer may be impacted by the increased annual use of willows by herbivores (larter & nagy 1997; larter 1999). in order to describe, in detail, the seasonal diet composition of peary caribou and muskoxen on banks island we embarked on a program to collect fresh faecal samples deposited on known dates during every month of the year. we hypothesized that muskoxen would feed on willow to a greater extent during the growing season when willow was of higher nutritive quality (larter & nagy 2001b) and/or during late-winter when the availability of sedge (carex spp., eriophorum spp.) would be lowest, due to the combination of grazing and snow conditions (larter & nagy 2000, 2001c). we also hypothesized that the diet composition of muskox would be different in areas of different muskox density. this paper documents the monthly diets peary caribou, the monthly diets of muskoxen residing in areas of both high and low muskox density, the percent similarity in diet between the two animals, and relates the monthly changes in diet to foraging behaviour. study area banks island is the westernmost island in the canadian arctic archipelago and covers approximately 70 000 km2 (fig. 1). the climate is arctic maritime along coastal areas where weather stations are located, tending toward arctic desert inland (zoltai et al. 1980). winters are long and cold; mean monthly temperatures are below 0 °c from september through may; mean minimum daily temperatures range from –30 °c to –40 °c from december to march. summers are short and cool; mean maximum daily temperatures range from 5 °c to 10 °c from june through august. there is little precipitation; the annual mean is 90 mm (zoltai et al. 1980). sachs harbour (population 125) is the only permanent settlement on the island. habitat descriptions were adapted from kevan (1974), wilkinson et al. (1976), and ferguson (1991). there are four major terrestrial habitats: 1) wet sedge meadow, 2) upland barren, 3) hummock tundra, and 4) stony barren. muskoxen and caribou forage in all habitats. wet sedge meadows (wsm) are generally level hydric and hygric lowlands characterized by carex aquatilis, eriophorum scheuchzeri, and dupontia fi sheri. upland barrens (ub) are well drained sites found on the upper and middle parts of slopes. vegetation is dominated by dryas integrifolia and salix arctica. hummock tundra (ht) is found on moderately steep slopes and is characterized by individual hummocks which are vegetated primarily by dwarf shrubs (d. integrifolia, s. arctica, with some cassiope tetragona). stony barrens (sb) have a coarse gravelly substrate and are found in windblown areas, on ridges and on gravel and sand bars; vegetation is sparse. the areas of high and low muskox density where samples were collected for this study cover 2700 and 18 400 km2, respectively, and have had distinctly different densities of muskox since 1985 (nagy et al. 1996). similar vegetation types and vegetation of similar quality are found throughout both areas (larter & nagy 2001b). however, in the low density area, vegetated habitats are more patchily distributed with sb being more prominent (larter & nagy unpubl. data) and latewinter snow conditions tend to be harsher (larter & nagy 2001c). a more detailed description of the fl ora of banks island can be found in wilkinson et al. (1976), porsild & cody (1980), and zoltai et al. (1980). plant taxonomy follows kartesz (1999). methods two fi eld camps were established in june 1993 on south central banks island (fig. 1): one camp (coyote) is located in an area of high muskox density (1.6 1.9 muskox/km2) about 90 km ese of sachs harbour, and the other (bernard) in an area of low muskox density (0.3 0.4 muskox/ km2) about 130 km ene of sachs harbour (fig. 1). from june 1993 to may 1998 we made six trips to these camps annually in june, july, august, november december, february, and april may. 133larter & nagy 2004: polar research 23(2), 131–140 fig. 1. the study area, banks island, northwest territories, canada. the hatched areas indicate where samples were collected from the high muskox density (western) and low muskox density (eastern) areas. the location of the coyote and bernard camps is indicated. 134 seasonal changes in composition of diets of peary caribou and muskoxen we collected fresh (< 4 hr old) peary caribou faecal samples opportunistically during all these fi eld trips. additional faecal samples were collected during fi eld trips in march and may 1993 and january 2001, from animals killed by hunters (since 1990), and from animals taken during a collection in winter 1993–94. in total 298 samples were analysed from all months, range of 10 to 49 samples/month. we present monthly diet composition pooled across sex and age classes and years with the individual caribou as the sample unit. we assume inter-annual variation was minimal. previous analyses (larter & nagy 1997) indicated that between-group variation was greater than within-group variation in the diet of muskox. therefore, we assumed that a composite sample of fresh (< 4 hr old) muskox faeces from a number of individuals in a group was representative of that group of muskox and that by sampling groups instead of individuals we would get a better measure of the diet over a larger portion of the muskox population. thus, we used the composite sample from a muskox group as the sample unit. initially (march 1993) the sample unit consisted of fi ve pellet groups; this was reduced to three pellet groups/muskox group. small pellets (i.e. from calves) were not included in composite samples. we collected faecal samples from mixed sex and age groups during fi eld trips conducted between march 1993 and may 1998 and during september, october, and december 2000 and january 2001. this provided data for all months of the year from the high density area, and for all months except january, september and december in the low density area. we recorded the number of individuals present in each group we collected faecal samples from. the number of groups sampled per month during the sampling period ranged from 2 to 29, representing between 63 and 634 animals in the high density muskox area, and from 1 to 23, representing between 30 and 371 animals, in the low density muskox area. we present mean monthly diet composition of muskoxen pooled across years with the group as the sample unit, weighted by the number of individuals in a group. january and september data from the high density area and may and october data from the low density area are from one year only. we assume inter-annual variation was minimal. faecal samples were thawed, air dried for 24 hr, oven dried at 60 °c for 48 hr, and ground through a 1 mm screen with a centrifugal mill. subsamples (ca. 1 g dry weight) were forwarded to the composition analysis laboratory, ft. collins, colorado, for analysis. diet composition was determined by analysing plant fragments (sparkes & malechek 1968) according to hansen et al. (1976). the microhistological technique has inherent limits, such as an inability to separate some species, and a limited percent of identifi able fragments in the slides (johnson et al. 1983; barker 1986). however, we deemed this method suitable for this study, since we were interested in the proportional dietary contribution of different forage classes, not of individual species. moreover, this method had been used in previous work on banks island (oakes et al. 1992; larter & nagy 1997). the diet was subdivided into the following forage classes: sedge (cyperaceae), willow (predominantly salix arctica), grass (poaceae), rose/saxifrage (rosaceae and saxifragaceae but predominantly dryas integrifolia), legume (oxytropis spp., astragalus spp.), fruticose lichen (cetraria spp., cladonia spp., cladina spp., peltigera spp., and thamnolia subuliformis), and other (other forbs, moss, and equisetum spp.). no samples had completely unidentifi able material. there were traces (≤ 1.93 %) of unidentifi able grass, and forb material. these were included in their respective categories. trace (≤ 0.1 %) quantities of rush were included as grass. we used simpson’s index (si) (krebs 1989) as a measure of monthly diet diversity. annual diet diversity was calculated as the mean of monthly si over twelve months for caribou and muskoxen in high density areas, and over eight months for muskoxen in low density areas. we used the renkonen index (renkonen 1938; krebs 1989) to compare monthly percent diet similarity (ps) between peary caribou and muskoxen in high and low muskox density areas. this index determines ps by summing the lower percentage of each individual forage class in the diets being compared. we compared monthly diet similarity between peary caribou and muskox both within and between months. we used the same forage classes as above except that the sedge class was subdivided into carex spp. and eriophorum spp. and that the moss component was reported separately from the other category. we considered ps > 50 % as substantial diet similarity. we used the sign test (conover 1980) to compare the amounts of willow and sedge in the diet of muskoxen in low and high density areas. 135larter & nagy 2004: polar research 23(2), 131–140 results the annual diet of caribou, simpson’s index (si) of 0.704, was more diverse than that of muskoxen in both high (si 0.433) and low (si 0.314) density areas, and was dominated by four forage classes: sedge, willow, legume, and rose/saxifrage (predominantly dryas integrifolia) which varied in their monthly contribution to the diet (fig. 2a). willow was the dominant dietary component during summer (june-august). legumes and dryas integrifolia represented ≥ 50 % of the diet from october to may. the sedge component of the diet was generally between 15 and 25 % for all months except january, april, may and july. lichen and grass use was negligible (≤ 5 %) except during january. diet diversity was greatest in january and september (si 0.811 and 0.809, respectively), when the four dominant forage classes made up < 75 % of the diet: 74 % in january and 66 % in september (fig. 2a). the annual diet of muskoxen in both high and fig. 2. monthly diet composition, mean percent relative density of faecal plant fragments, of a) peary caribou, b) muskoxen in high density areas, and c) muskoxen in low density areas. values over each histobar are the number of samples. for caribou, samples represent individuals. for muskoxen, samples represent groups. an asterisk indicates data from one year only. 136 seasonal changes in composition of diets of peary caribou and muskoxen low density areas was dominated by two forage classes, sedge and willow (fig. 2b, c). sedge and willow made up ca. 95 %, or more, of the diet in all months except july, when legume use was noticeable. muskoxen in high density areas tended to have somewhat more willow and less sedge (p < 0.01; 1-tailed) in their monthly diets when compared to muskox in low density muskox areas (fig. 2b, c). in high density areas, substantial willow use (48 75 %) occurred during fi ve months of the year: january, may, june, september and october. in low density areas, willow use was highest during october (46 %), may (25 %), and june (20 %); there were no data for january and september. only in june was there substantial overlap (71 %) in diet between peary caribou and muskox in high density areas. however, there was substantial overlap between the summer (june august) diet of caribou and the fall diet (september and october) of muskox and between the july diet of muskox and the february, march and june diet of caribou (table 1). the april diet of peary caribou, with its low sedge and willow content, was the least similar to the diet of muskoxen. similar patterns of diets were found for peary caribou and muskox in low density areas (table 2). for any month, the diets of muskoxen in high and in low density areas had substantial similarity (table 3). in the three months with lowest similarity (may 57 %, june 51 % and october 67 %) the greater use of willow by muskoxen in high density areas relative to those in low density areas caused the reduction in diet similarity (table 3; fig. 2b, c). discussion at the start of the growing season the levels of anti-herbivore defence compounds in deciduous species are low (chapin et al. 1980) and willow leaves are of their highest quality (murray 1991; larter & nagy 2001b). muskoxen grazed almost exclusively on willow leaves during the start of the growing season at sverdrup pass, ellesmere island (murray 1991; raillard 1992). similarly, we found high use of willow by muskoxen during may and june, consistent with the hypothesis that foraging on willow occurs during the early growth stages when leaves and young shoots are emerging and plants are of high nutritive quality. we did not expect muskoxen would feed on willow to such an extent during the fall (september and october) and in january (fig. 2b, c). the fi bre and lignin content of willow leaves and stems increases over the course of the growing season with a corresponding decrease in digestibility (hartley & jones 1997; larter & nagy 2001b). by fall and winter, willow leaves and stems have lignifi ed and are certainly not of the high nutritive quality they were at the start of the growing season. sample sizes for these months were smaller than for other months and may not have provided an accurate refl ection of the diet; however, the percent willow in any individual sample was ≥ 37 % which implies willow was an important dietary component for muskoxen during september, october and january. the diet of cape bathurst caribou (rangifer tarandus groenlandicus), found on the maintable 1. the renkonen index of percent similarity between the monthly diets of muskox and caribou in high muskox density areas. substantial overlap (> 50 %) indicated by bold print. jan. feb. mar. apr. may jun. jul. aug. sep. oct. nov. dec. january 20.8 27.4 27.9 28.7 27.5 26.9 43.4 26.7 27.4 23.7 21.9 26.5 february 25.6 26.7 27.2 26.8 21.7 51.3 26.0 28.1 24.0 22.6 25.2 march 38.1 38.9 37.6 33.0 62.2 36.8 33.2 29.5 27.6 34.9 april 13.6 12.9 12.4 37.4 12.1 16.9 13.0 10.5 11.6 may 24.8 24.2 49.3 24.0 28.6 24.9 22.3 23.9 june 70.8 53.1 37.7 60.6 57.2 27.7 52.4 july 24.9 18.0 58.9 84.2 21.9 41.0 august 29.5 67.5 63.7 32.1 50.7 september 36.0 32.2 30.4 37.5 october 27.1 25.3 28.7 november 25.8 32.1 december 31.1 137larter & nagy 2004: polar research 23(2), 131–140 land of the northwest territories to the south of banks island, was > 85 % willow during late june and july (n. larter & j. nagy unpubl. data), and we expected peary caribou, being a mixed feeder, also to forage on high quality patchily distributed forage such as willow during the growing season. during july the peary caribou diet was least diverse (si 0.276) and willow made up 85 % of the diet. in june and august, willow constituted ca. 45 % of the diet of peary caribou on banks island (fig. 2a). willow use peaked in july when the available biomass of willow leaf crude protein was at its greatest (larter & nagy 2001b; n. larter & j. nagy unpubl. data). this pattern of foraging is consistent with the multiplier effect in ruminant physiology (white 1983), where selective foraging on high quality foods has a positive infl uence on animal production, and it occurred during a period of milk production (for females) and fat deposition. body size and fat reserves have a powerful effect on calf production and age of fi rst reproduction of reindeer and caribou (dauphine 1976; leader-williams 1980; thomas 1982). some studies indicated that legumes were an important component of the summer diet of muskoxen on banks island and that their foraging behaviour may shape regrowth and reproduction of oxytropis borealis (oakes et al. 1992; mulder & harmsen 1995). we found a fair amount of legume in the july diet of muskoxen, but negligible use during the other months of the year. legumes were at their highest digestibility in july (larter & nagy 2001b). selective feeding on highly digestible legumes in july may represent a multiplier effect (white 1983) for banks island muskoxen. the proportion of legume in the july diet was higher for muskoxen in high density areas (fig. 2b, c). legumes made up substantial portions of the monthly diet of caribou from october through may; july was the only month caribou did not feed on legumes (fig. 2a). legumes are an ideal forage for mixed feeders like caribou during winter. they are patchily distributed throughout upland habitats (larter & nagy 2001d) and have a substantially higher crude protein content (ca. 12 %) than other available forages (larter & nagy 2001b). larter & nagy (1997) indicated that the differences in the diet of muskoxen between areas of high and low density may have been related to forage availability. greater use of legumes by muskoxen in high density areas may be a result of table 2. the renkonen index of percent similarity between the monthly diets of muskox and caribou in low muskox density areas. substantial overlap (> 50 %) indicated by bold print. feb apr may jun jul aug oct nov february 21.6 27.4 25.4 28.2 36.9 27.0 22.7 23.7 april 13.8 11.9 14.3 23.1 13.2 11.5 9.9 may 23.8 26.2 35.0 20.9 23.2 19.2 june 49.6 54.2 33.5 56.2 22.1 july 24.2 12.7 53.7 13.2 august 25.3 62.6 23.5 october 25.4 27.9 november 24.2 table 3. the renkonen index of percent similarity between the monthly diets of muskox in high and low muskox density areas. substantial overlap (> 50 %) indicated by bold print. feb apr may jun jul aug oct nov february 79.5 87.3 37.9 66.5 77.4 86.0 64.5 87.8 april 94.0 43.0 72.2 81.5 90.3 63.1 82.7 may 56.9 71.9 67.3 55.8 82.7 47.8 june 50.7 46.4 35.2 58.8 24.9 july 83.4 63.0 61.4 55.6 august 88.3 61.6 72.7 october 66.6 28.1 november 91.3 138 seasonal changes in composition of diets of peary caribou and muskoxen availability. the frequency of occurrence (larter & nagy 2001d) and aboveground standing crop (n. larter & j. nagy unpubl. data) of legumes was greater in habitats in the high muskox density area. this was not the case for willows or sedges in wet sedge meadows, which had similar availability in areas of high and low muskox density; yet the willow proportion of the diet in summer is greater for muskoxen in high density areas. larter & nagy (2001a) indicated that a per capita decrease in summer sedge availability at peak muskox densities was the likely cause of the larger willow component of the summer diet. greater intraspecifi c competition for sedge would explain why sedge remained a lower proportion of the summer diet of muskoxen in high density areas (fig. 2b). during winter, muskoxen in the high arctic generally forage in moister habitats where there is an abundance of monocots, generally sedge (urquhart 1973; schaefer & messier 1995a, 1995b; thomas et al. 1999; larter and nagy 2001c). this would be expected of a grazing animal. if muskox select wet sedge meadow habitat throughout winter, why do muskoxen in high density areas have so much willow in the diet during some months? sedges do constitute the majority of forage biomass in wet sedge meadows on banks island; however, willow is often found in this habitat (larter & nagy 2001d). we believe that the decrease in the sedge component and the increase in the willow component of the diet from november to january is caused by changing forage availability in wet meadows as a result of foraging by muskoxen, and the onset of 24-hr darkness. muskox move into wet meadows once the ground is frozen in november and actively forage on sedges, thus decreasing sedge biomass relative to willow biomass and making the snow cover harder as a result of cratering for forage. during the period of 24-hr darkness and after the onset of extreme cold (december through mid-january) there appears to be a reluctancy to search for ungrazed meadows. in february, with the rapid return of daylight, we believe that the animals search for ungrazed meadows to meet foraging requirements and again remain in these localized areas through march, as indicated by a decrease in the sedge and an increase in the willow component of the diet. by mid-april the extreme cold has ended, daylight lasts almost 24 hr and we believe muskoxen then actively seek ungrazed meadows in which to forage. this would coincide with the time (april and may) when muskox show an increase in energy expenditure (lawler & white 1997). whether the pattern is the same in areas of low muskox density is unknown because of a lack of data. the similarity between the diets of peary caribou and muskoxen in high density areas during any given month was < 40 % except during june, when there was substantial diet similarity (71 %; table 1). however, diet similarity in any given month does not completely address the potential for food competition. foraging during the nongrowing season clearly has a direct impact on the availability of forage in the non-growing season, but it may also impact availability in the following growing season. the june diet of peary caribou shows substantial similarity to the june, july, september, october and december diets of muskoxen—particularly in their willow components— and the september and october diets of muskoxen have substantial overlap with the june, july and august diets of peary caribou. therefore for fi ve months of the year the diet of muskoxen is similar to the summer diet of caribou. given this similarity between their diets, even though the two species may not forage in the same areas at the same time, there is potential for competition should food become limiting. inter-annual variation in diet could potentially affect our results, particularly if there were directional changes in diet over time or if greater or lesser sampling intensity occurred during a year in which diet was different from that in most years. changes in the quality and/or availability of forages would be important factors in interannual variation in diet. larter & nagy (2001b) found annual variability in the quality of forages on banks island, but these changes were consistent across all forages and across areas of both high and low muskox density. there was annual variation in the standing crop of forages on banks island, but this was not consistent across habitat types (n. larter & j. nagy unpubl. data). given the variability in diet of individual caribou and groups of muskoxen, and the lack of evidence for any directional change in forage quality or availability, any inter-annual variability in diet would not drastically affect the dietary patterns we describe. although data were not collected specifi cally to investigate changes in diet that may be related to winter forage availability, many faecal samples were collected during a period when winter snow conditions (larter & nagy 2000) and winter 139larter & nagy 2004: polar research 23(2), 131–140 foraging behaviour (larter & nagy 2001d) were investigated. winters 1996–97 and 1997–98 were less severe with shallower and softer snow cover than previous winters; there was very little snow cover in november 1997 (larter & nagy 2000; 2001d). shallower snow conditions in early winter may have increased lichen availability, as suggested by the observation that the amount of lichen in the november diet of peary caribou in 1997 was larger than november in other years, 10.3 % (n = 5) in 1997, versus mean of 1.4 % (n = 44) in 1991, 1993–96. less severe snow conditions may also increase the availability of legumes relative to dryas integrifolia for caribou. the absolute amount of legume and the ratio of d. integrifolia to legume in the november diet of caribou during 1996 and 1997 (n = 10) was greater than for four (n = 39) of the previous years (41 versus 27 % and 1.1 versus 0.9, respectively). acquiring a higher proportion of legumes and consequently a diet of higher protein content during winter could be advantageous for banks island peary caribou. the numbers of both muskoxen and peary caribou on banks island have remained high over the past decade: 50 000 to 65 000 muskoxen over the age of one year, and 500 to 1200 caribou over the same age (nagy et al. 1996; larter & nagy 1997; j. nagy & n. larter unpubl. data). in addition to peary caribou and muskoxen herbivory, arctic willows make up a considerable amount of the winter diets of arctic hares (lepus arcticus) and ptarmigan (lagopus mutus, l. lagopus) (klein & bay 1990; larter 1999; n. larter & d. hik unpubl. data). can willows sustain the substantial amounts of herbivory to which they are currently being exposed? willows that were released from browsing on banks island did not alter the ratio of leaf biomass to stem diameter compared to browsed plants; however, plants that were not browsed had larger diameter stems resulting in an increase in total leaf biomass of 30 % (larter & hik in press). arctic willows appear to be relatively tolerant of herbivory, but there is some indication that vegetative growth is becoming dominated by younger and narrower stems. should herbivory on willows result in reduced willow biomass, the peary caribou population would incur more of a negative impact than the muskoxen population because caribou feed selectively on high quality willows during summer when the animals are growing and putting on fat reserves. a reduction in willow biomass would reduce the potential for caribou numbers to increase. acknowledgements.—we thank the following for fi eld and lab assistance during the course of the study: s. baryluk, a. esau, e. esau, l. gordon, s. gray, j. lennie, j. lucas sr., t. lucas, f. raddi, l. raddi, p. raddi, w. raddi, and d. semple. we thank all the hunters in sachs harbour who provided caribou faecal samples. t. foppe and colleagues at the composition analysis lab are gratefully acknowledged for comments and insight into the microhistological technique. s. carrière provided comments on early drafts of this manuscript. major funding for this project was provided through the inuvialuit final agreement. references barker, r. d. 1986: an investigation into the accuracy of herbivore diet analysis. aust. wildl. res. 13, 559–568. chapin, f. s., iii., johnson, d. a. & mckendrick, j. d. 1980: seasonal movement of nutrients in plants of differing growth form in an alaskan tundra ecosystem: implications for herbivory. j. ecol. 68, 189–209. conover, w. j. 1980: practical nonparametric statistics 2nd edition. new york: john wiley & sons, inc. dauphine, jr., t. c. 1976: growth, reproduction and energy reserves. part 4: biology of the kaminuriak population of barren-ground caribou. can. wildl. serv. rep. ser. 38. ferguson, r. s. 1991: detection and classifi cation of muskox habitat on banks island, northwest territories, canada, using landsat thematic mapper data. arctic 44, 66–74. hansen, r. m., foppe, t . m., gilbert, m. b., clark, r. c. & reynolds, h. w. 1976: the microhistological analyses of feces as an estimator of herbivore diet. unpublished report available from the department of range science, colorado state university, ft. collins, co, usa. hartley, s. e. & jones, c. g. 1997: plant chemistry and herbivory: or why the world is green. in m. j. crawley (ed): plant ecology. 2nd edition. pp. 284–324. oxford: blackwell scientifi c. hofmann, r. r. 1989: evolutionary steps of ecophysical adaption and diversifi cation of ruminants: a comparative view of their digestive system. oecologia 78, 443–457. hofmann, r. r. 2000: functional and comparative digestive system anatomy of arctic ungulates. rangifer 20, 71–81. ihl, c. 1999: comparative habitat and diet selection of muskoxen and reindeer on the seward peninsula, western alaska. msc thesis, university of alaska, fairbanks. ihl, c. & klein, d. r. 2001: habitat and diet selection by muskoxen and reindeer in western alaska. j. wildl. manage. 65, 964–972. johnson, m. k., wofford, h. & pearson, h. a. 1983: digestion and fragmentation: infl uence on herbivore diet analysis. j. wildl. manage. 47, 877–879. kartesz, j. t. 1999: a synonymized checklist and atlas with biological attributes of the vascular fl ora of the united states, canada, and greenland. first edition. in j. t. kartesz & c. a. meacham (eds): synthesis of the north american fl ora, electronic version 1.0. chapel hill, north carolina: north carolina botanical garden. kevan, p. g. 1974: peary caribou and muskoxen on banks island. arctic 27, 256–264. klein, d. r. 1992: comparative ecological and behavioral adaptions of ovibos moschatus and rangifer tarandus. rangifer 12, 47–55. 140 seasonal changes in composition of diets of peary caribou and muskoxen klein, d. r. & bay, c. 1990: foraging dynamics of muskoxen in peary land, northern greenland. holarctic ecol. 13, 269–280. krebs, c. j. 1989: ecological methodology. new york: harper and row publishing. larter, n. c. 1999: seasonal changes in arctic hare, lepus arcticus, diet composition and differential digestibility. can. field natural. 113, 481–486. larter, n. c. & hik, d. s. in press: response of arctic willow (salix arctica) following release from herbivory in a high arctic ecosystem. arctic. larter, n. c. & nagy, j. a. 1997: peary caribou, muskoxen and banks island forage: assessing seasonal diet similarities. rangifer 17, 9–16. larter, n. c. & nagy, j. a. 2000: annual and seasonal differences in snow depth, density, and resistance in four habitats on southern banks island, 1993-1998. department of resources, wildlife & economic development, manuscript report 136. larter, n. c. & nagy, j. a. 2001a: calf production, calf survival, and recruitment of muskoxen on banks island during a period of changing population density from 1986-1999. arctic 54, 394–406. larter, n. c. & nagy, j. a. 2001b: seasonal and annual variability in the quality of important forage plants on banks island, canadian high arctic. appl. veg. sci. 4, 115–128. larter, n. c. & nagy, j. a. 2001c: variation between snow conditions at peary caribou and muskox feeding sites and elsewhere in foraging habitats on banks island in the canadian high arctic. arct. antarct. alp. res. 33, 123–130. larter, n. c. & nagy, j. a. 2001d: distribution of forage types among four terrestrial habitats on southern banks island. department of resources, wildlife & economic development, manuscript report 142. lawler, j. p. & white, r. g. 1997: seasonal changes in metabolic rates of in muskoxen following twenty-four hours of starvation. rangifer 17, 135–138. leader-williams, n. 1980: population ecology of reindeer on south georgia. in e. reimers, e. gaare & s. skjenneberg (eds): proceedings of the second international reindeer/ caribou symposium, røros, norway, 1979. pp. 664–676. trondheim: direktoratet for vilt og ferskvannsfi sk. mckendrick, j. d. 1981: responses of arctic tundra to intensive muskox grazing. agroborealis 12, 49–55. mulder, c. p. h. & harmsen, r. 1995: the effect of muskox herbivory on growth and reproduction in an arctic legume. arct. alp. res. 27, 44–53. murray, j. l. 1991: biomass allocation and nutrient pool in major muskoxen-grazed communities in sverdrup pass, 79o n, ellesmere island, n.w.t., canada. msc thesis, university of toronto. nagy, j. a., larter, n. c. & fraser, v. p. 1996: population demography of peary caribou and muskox on banks island, n.w.t., 1982–1992. rangifer 9, 213–222. oakes, e. j., harmsen, r. & eberl, c. 1992: sex, age, and seasonal differences in the diets and activity budgets of muskoxen (ovibos moschatus). can. j. zool. 70, 605-616. parker, g. r. 1978: the diets of muskoxen and peary caribou on some islands in the canadian high arctic. canadian wildlife service, occasional paper 35. porsi1d, a. e. & cody, w. j. 1980: the vascular plants of continental northwest territories, canada. ottawa: national museum of canada. raillard, m. 1992: infl uence of muskox grazing on plant communities of sverdrup pass (79°n), ellesmere island; n w t, canada. phd thesis, university of toronto. reimers, e., villmo, l., gaare, e., holthe v. & skogland, t. 1980: status of rangifer in norway including svalbard. in e. reimers, e. gaare & s. skjenneberg (eds): proceedings of the second international reindeer/caribou symposium, røros, norway, 1979. pp. 774–785. trondheim: direktoratet for vilt og ferskvannsfi sk. renkonen, o. 1938: statistisch-ökologische untersuchungen über die terrestriche käferwelt der fi nnischen bruchmoore. (statistical-ecological investigation of the terrestrial beetle population of finnish bogs.) ann. zool. soc. bot. fenn. vanamo 6, 1–231. schaefer, j. a. & messier, f. 1995a: habitat selection as a hierarchy: the spatial scales of winter foraging by muskoxen. ecography, 18: 333–344. schaefer, j. a. & messier, f. 1995b: winter foraging by muskoxen: a hierarchical approach to patch residence time and cratering behaviour. oecologia, 104: 39–44. shank, c. c., wilkinson, p. f. & penner, d. f. 1978: diet of peary caribou, banks island, n.w.t. arctic 31, 125–132. sparkes, d. r. & malechek, j. c. 1968: estimating percentage dry weights using a microscopic technique. j. range manage. 21, 264–265. svendsen, c. r. 1992: utilizaion of riparian willow stands during summer by moose, muskoxen, and reindeer on the seward peninsula, alaska. in b. bobek, k. perzanowski & w. regelin (eds): global trends in wildlife management. transactions of the 18th international union of game biologists congress, krakow, poland, 1987. pp. 233–236. krakow-warszawa: swiat press. thing, h. 1984: feeding ecology of the west greenland caribou (rangifer tarandus groenlandicus) in the sisimiutkangerlussuaq region. dan. rev. game biol. 12, 1–53. thing, h., klein, d. r., jingfors, k. & holt, s. 1987: ecology of muskoxen in jameson land, northeast greenland. holarctic ecol. 10, 95–103. thomas, d. c. 1982: the relationship between fertility and fat reserves of peary caribou. can. j. zool. 60, 597–602. thomas, d. c. & edmonds, j. e. 1983: rumen contents and habitat selection of peary caribou in winter, canadian arctic archipelago. arct. alp. res. 15, 97–105. thomas, d. c. & edmonds, j. e. 1984: competition between caribou and muskoxen, melville island, nwt, canada. biological papers of the university of alaska, special report 4, 93–100. thomas, d. c., edmonds, e. j. & armbruster, h. j. 1999: range types and their relative use by peary caribou and muskoxen on melville island, n. w. t. canadian wildlife service, technical report series number 343. tyler, n. j. c. & blix, a. s. 1990: survival strategies in arctic ungulates. rangifer special issue 3, 211–230. urquhart, d. r. 1973: oil exploration and banks island wildlife. a guideline for the preservation of caribou, muskox and arctic fox populations on banks island, n.w.t. northwest territories game management division. unpublished manuscript available at the department of resources, wildlife and economic development, government of the northwest territories, yellowknife, nt, canada x1a 2l9. white, r. g. 1983: foraging patterns and their multiplier effects on productivity of northern ungulates. oikos 40, 377-384. wilkinson, p. f., shank, c. c. & penner, d. f. 1976: muskoxcaribou summer range relations on banks island, n. w. t. j. wildl. manage. 40, 151–162. zoltai, s. c., karasiuk, d. j. & scotter, g. w. 1980: a natural resource survey of the thomsen river area, banks island, n. w. t. unpublished report prepared for parks canada, available at canadian wildlife service, edmonton, alberta, canada, t6v 2x3. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <feff004200720075006700200064006900730073006500200069006e0064007300740069006c006c0069006e006700650072002000740069006c0020006100740020006f0070007200650074007400650020005000440046002d0064006f006b0075006d0065006e0074006500720020006d006500640020006800f8006a006500720065002000620069006c006c00650064006f0070006c00f80073006e0069006e0067002000740069006c0020007000720065002d00700072006500730073002d007500640073006b007200690076006e0069006e0067002000690020006800f8006a0020006b00760061006c0069007400650074002e0020005000440046002d0064006f006b0075006d0065006e007400650072006e00650020006b0061006e002000e50062006e006500730020006d006500640020004100630072006f0062006100740020006f0067002000520065006100640065007200200035002e00300020006f00670020006e0079006500720065002e00200044006900730073006500200069006e0064007300740069006c006c0069006e0067006500720020006b007200e600760065007200200069006e0074006500670072006500720069006e006700200061006600200073006b007200690066007400740079007000650072002e> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice doi:10.3402/polar.v34.24289 r e s e a r c h / r e v i e w a r t i c l e the significant inputs of trace elements and rare earth elements from melting glaciers in antarctic coastal waters intae kim,1,2 guebuem kim2 & eun jung choy1 1 division of polar ocean environment, korea polar research institute, incheon 406-840, republic of korea 2 school of earth and environmental sciences/rio, seoul national university, seoul 151-747, republic of korea keywords iron; trace elements; rare earth elements; glacier melting; antarctica; marian cove. correspondence guebuem kim, division of polar ocean environment, korea polar research institute, incheon 406-840, republic of korea. e-mail: gkim@snu.ac.kr abstract to evaluate the impact of modern glacier melting on the chemical enrichment of antarctic coastal waters, we measured trace elements, including dissolved iron (fe) and rare earth elements (rees), together with dissolved inorganic nitrogen, phosphorous, silicate and dissolved organic carbon (doc) in ice, snow and coastal seawater of marian cove in the northernmost part of antarctica (628s). there was an increase in the concentrations of fe and other trace elements (al, mn, cr, ni, co, pb and rees) between the bay mouth and the glacier valleys. good correlations between salinity and these chemical elements indicate that the trend was mainly due to the influence of glacier meltwater (gmw). when the effect of gmw was quantified based on plots of its presence (average 5.7%) in the surface water of the cove, the concentrations of trace elements in seawater increased 18-fold for fe, eightto 10-fold for al and mn and up to four-fold for cr, ni, co, pb and rees by gmw. however, the contribution of gmw to inorganic nutrients and doc was negligible. the significance of gmw-borne ree contribution in this cove was further evidenced by middle ree enrichment in cove water. our results suggest that the currently increasing glacier melting in antarctica has a significant influence on the level of trace elements, particularly fe, in cove water, which in turn may have a significant impact on the biogeochemistry of coastal seawater in antarctica. at the latest count, there were approximately 200 000 icebergs in the southern ocean, with linear dimensions between 50 m and tens of kilometres (williams et al. 1999; smith et al. 2007). depending on their size, some icebergs are grounded whereas others can drift over hundreds to thousands of kilometres within several weeks (schodlok et al. 2006; schwarz & schodlok 2009; luckman et al. 2010). antarctic glaciers have retreated in recent years, which has resulted in a loss of mass from ice shelves (scambos et al. 2000; bindschadler & rignot 2001; long et al. 2002; rignot & steffen 2008; rignot et al. 2013). the disintegration of antarctic ice shelves over the past 50 years has been attributed to several processes: atmospheric warming (cook & vaughan 2009), an increase in basal melt of glaciers by warm waters (jacobs et al. 2011; pritchard et al. 2012) and changes in coastal polynyas (khazendar et al. 2013). such processes have contributed to an increase in the numbers of icebergs in the southern ocean (rignot & thomas 2002; velicogna & wahr 2006; rignot et al. 2011). glaciers acquire a significant load of terrigenous material through glacial processes, dust accumulation and direct contact with shelf sediments. glacier fragments (or ice fragments) containing elevated levels of land-borne material are released directly into ambient waters by melting (maher & dennis 2001; raiswell et al. 2008). the increase in iceberg calving from antarctica over the last few decades has therefore provided new opportunities to evaluate the significance of terrestrial micronutrient inputs into the southern ocean (smith et al. 2007; shaw et al. 2011; alderkamp et al. 2012). for example, glaciers have been suggested as an important source of iron (fe) polar research 2015. # 2015 i. kim et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 to the surrounding waters (de baar et al. 1995; raiswell et al. 2008; raiswell 2011). amongst terrigenous elements, fe is particularly important in the southern ocean because it can limit primary productivity (martin 1990; buma et al. 1991; sunda & huntsman 1997; coale et al. 2003). recent studies have shown the potential importance of glacier melting to the supply of new fe and the subsequent effect on marine production in the southern ocean (statham et al. 2008; schwarz & schodlok 2009; lin et al. 2011; alderkamp et al. 2012). shaw et al. (2011) reported that free drifting icebergs are important for terrigenous material inputs to surface waters in the southern ocean. gerringa et al. (2012) also suggested that large fe inputs from pine island glaciers by the lateral advection could supply the total fe demand by a phytoplankton bloom. more recently, bhatia et al. (2013) showed that the annual flux of bioavailable fe from greenland ice meltwater was comparable to that of dustderived soluble fe inputs to the north atlantic. however, little is known about the role of melting glaciers on the distribution of trace elements in the surrounding seawater because their sources are diverse and the interactions with the ecosystem are highly dynamic. the main objectives of this study are (1) to determine the distribution of dissolved trace elements including fe and rare earth elements (rees), dissolved inorganic nitrogen (din), phosphorous (dip), silicate (dsi) and dissolved organic carbon (doc) in ice floats, snow and coastal seawater and (2) to quantify trace elements and chemical components derived from antarctic glacier melts in a coastal embayment. this study was conducted at marian cove, which is located south of the antarctic polar front (fig. 1). it was selected as an ideal place to study the impacts of glacial melt on coastal waters because glacier valleys drain into marian cove and deliver large volumes of turbid glacier meltwater (gmw) during the austral summer (shim et al. 2011). materials and methods study area this study was conducted at marian cove near the king sejong research base (korean antarctic station; 628s, 59.78w) from 21 to 28 january 2012 (fig. 1). the base is located on the barton peninsula on king george island, the largest island in the south shetland archipelago (fig. 1). marian cove (3.5 km long and 1.2 km wide) is a small fjord with a maximum depth of about 100 m and is located in an inlet of maxwell bay, south of the antarctic polar front (yoo et al. 2000). surface temperatures and salinities in the cove range from �2 to 28c (average �0.48c) and from 32 to 35 (average 33.8), respectively (shim et al. 2011). marian cove is free of sea ice for most of the year, but thick annual sea ice appears during winter. during the austral summer, the cove is completely ice-free (from november to february), which leads to enhanced biological productivity (klöser et al. 1993; ahn et al. 1997). small valley glaciers draining into marian cove deliver icebergs and large volumes of turbid meltwater during the summer months (yoon et al. 1998). most ice-rafted debris originates from icebergs calved off the edges of glaciers, whereas fine-grained particles are discharged by glacier melt during the summer (shim et al. 2011). substantial amounts of snow meltwater are also discharged into the bay during this period, although the volume attributed to this type of meltwater has not yet been determined. sampling surface seawater samples for dissolved trace elements analysis was collected from the coastline or on board a zodiac boat using a handle sampler (1 l polyethylene dipper with a 4 m handle length). the dippers were soaked and pre-cleaned with double-distilled 1 m ultrapure hno3 (65%, thermo fisher scientific, waltham, ma, usa) for at least 24 h before sampling. salinities were measured in situ using an ysi 30 portable conductivity sensor (ysi, yellow springs, oh, usa) and an ocean seven 304 conductivity�temperature�depth logger (idronaut, brugherlo, italy). ice samples that had drifted to the coast after calving events were manually collected from the near-shore region and bagged in clean plastic zippered bags. back in the laboratory, the ice samples were rinsed briefly with distilled water to remove any possible surface contamination, and the rinse water was left to drip from the ice for a few minutes. finally, the ice samples were transferred to new clean zippered bags and melted completely for trace element analyses. old glacier ice and recently formed ice were included in the ice samples, but no sea ice was present. snow samples consisting of a mixture of recently formed and old glacier ice were collected in acidcleaned high-density polyethylene (hdpe) bottles from land sites near king sejong base (fig. 1) and transported to the clean laboratory bench. all samples were collected in hdpe bottles (1 l) that had been pre-cleaned with 1 m ultra-pure hno3 and then rinsed with de-ionized water (diw). the samples were double-bagged with clean plastic zippered bags and moved to the clean bench at king sejong base where fe, trace elements and rare earth elements from melting glaciers i. kim et al. 2 (page number not for citation purpose) citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 they were passed through a pre-cleaned membrane filter (0.45 mm, mixed cellulose ester) and then acidified with 6 m ultra-pure hno3 (15.8 m, thermo fisher scientific) to 0.03 m of hno3 (phb1.5) within 5 h of initial sampling. the samples were then stored in a freezer for later analyses. pre-concentration of trace elements in this study, we define dissolved trace elements as the total amount of trace elements extracted by a chelex 100 column (bio-rad, hercules, ca, usa). colloidal and nanoparticulate phases retained on the column were also included in the measurements. these phases were not retained by the physical filtration process as they are much smaller than the pore size of the packed column (10 mm), and it was therefore considered that they were retained by a surface reaction or binding. the concentrations of dissolved trace elements (including fe) in water samples were measured using the chelex 100 resin column method developed by lewis & landing (1991), öztürk (1995), öztürk et al. (2003) and ardelan et al. (2010), and recently improved by kim & kim (2011) and jeong et al. (2012). briefly, the aqueous samples (100� 500 ml) were adjusted to ph 5.7�5.9 using pure ch3cooh (99.7%, junsei chemical co., tokyo, japan) and nh3 (28%, junsei). then, the samples were passed through a chelex 100 resin (1.2 g, wet weight) column at ma rian co ve 0 0.5 1 km barton peninsula weaver peninsula ice cap 59° 44’ w59° 46’ w59° 48’ w 62° 13’ s 62° 14’ s penguin rookery 0 10 20km 62° 15’ s 62° 00’ s 62° 00’ s 62° 15’ s 59 ° 00 ’ w 59 ° 30 ’ w 58 ° 30 ’ w 58 ° 00 ’ w 58 ° 00 ’ w king sejong (kor) king george island d r a k e p a s s a g e b r a n s f i e l d s t r a i t 0 500 1000km 50°s 60°s 70°s chile southern ocean south atlantic ocean south pacific ocean indian ocean south pacific ocean kin g s ejo ng bas e n g la ci er gl ac ier iceberg-dominated area mc1 mc6 seawater iceberg snow 100 100 100 50 50 20 20 20200 300 mc2 mc3 mc4 mc5 mc7 mc8 1 2 3 4 5 1 2 3 4 5 king sejong base fig. 1 location of marian cove near the korean antarctic station, king sejong, on king george island. sampling sites for seawater, ice floats and snow are indicated. i. kim et al. fe, trace elements and rare earth elements from melting glaciers citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 a flow rate of less than 1.2 ml min �1 . the chelex 100 resin was pre-cleaned with 2 m hno3 followed by diw (resistivity �18.2 mv) (human power, seoul, korea) and then soaked in 1 m ammonium acetate overnight before being packed into the column, which effectively buffered the resin at ph 6. the size of the column used in this study was 85 mm �8 mm (eichrom technologies, lisle, il, usa). eight millilitre of the 1 m ammonium acetate solution (sigma aldrich, st. louis, mo, usa) and 5 ml of diw were used to wash out the interfering elements, and the trace elements absorbed onto the resin were then eluted with 1.5�2.0 ml of 2 m hno3. all procedures for the extraction of trace elements from samples were conducted at a clean bench (class-100) installed at king sejong base. the determination of trace elements using inductively coupled plasma mass spectrometry dissolved trace elements were measured by inductively coupled plasma mass spectrometry (model x-ii, thermo scientific waltham, ma, usa). the standards used for trace elements and rees were diluted from standard stock solutions (scp science, quebec, canada). the procedural blank values (n �9) were 2409150, 391, 1292, 2694, 591, 1298 and 1693 pm for al, cr, mn, ni, cu, zn and pb, respectively. the procedural blank values of co and cd were lower than the detection limits (b1 pm). our total procedural blank values were obtained from full volume (500 ml) samples of artificial seawater for all steps of pre-concentration and analysis. the blank concentrations are therefore for pre-concentrated (about 250fold) solutions. all blank values were lower than 5% of the average seawater concentrations, with the highest value for fe (about 5%). the recovery test for this column extraction method was conducted by spiking approximately 100 times the average seawater concentrations of trace elements to the seawater samples. when these spiked samples were pre-concentrated, the recoveries of al, cr, mn, fe, co, ni, cu, zn, cd and pb were 103911, 9296, 97915, 87917, 93910, 88916, 75917, 108931, 118934 and 11099% (n �3 for trace metals and n �9 for fe), respectively. the recovery efficiencies for seawater samples were higher than 90% for most of these trace elements. all the concentrations in this study were corrected by this recovery factor. to check the validity of this method, we also analysed common seawater reference samples (cass-4 and nass-5, national research council of canada) for trace elements (table 1). the validity of this method for fe was tested more carefully. the chelex 100 blank for fe was b0.36 nm, which falls in the range of blanks from other studies (0.290.08 nm fe) using the same resin (öztürk 1995; ardelan et al. 2010). the levels of fe for the reagent blanks (ultra-pure hno3, ch3cooh, nh3 and ammonium acetate solution, n �18) and procedural blanks (n �25) were 0.190.04 nm and 0.390.1 nm, respectively. our total blank level of fe was similar to the values from other recent studies (0.1�0.25 nm) that used different analytical methods (ardelan et al. 2010; milne et al. 2010; lee et al. 2011). the detection limit of fe was 0.14 nm, which was three times the standard deviation of the instrumental blanks. the procedural blank values for la, ce, nd, tb, tm and lu (i.e., rees) were 4.5, 1.4, 1.3, 0.4, 0.7 and 0.5 pm, respectively, whereas values for the other rees were not detectable. the instrumental detection limits of la and gd were 4.0 and 2.7 pm, respectively, while those of the other elements were b2 pm. the extraction efficiencies for rees were �95%. the relative standard deviation (rsd%) of each ree measurements was lower than 2, 3 and 5% for the light, middle and heavy ree (lree, mree and hree), respectively. the bao/eu and ceo/ce ratios were found to be lower than 2 and 1%, respectively, when 1 ppb of rees was measured before the sample measurement. although the chelex resin extraction method eliminates most of the major alkaline and alkaline earth metals (na � , mg 2� , k � , and ca � ), up to 75 nm of ba concentrations remained in the extracted samples. because high amounts of ba and its oxides, such as bao or baoh�, can lead to polyatomical interferences to eu, 151 eu and 153 eu were monitored using ba solutions of 15�70 nm, which are similar to the range observed in the eluted solution of seawater. in all trials (n �50), no eu was detected, except for in a few cases where b3 pm eu (b4% of the eu concentrations in seawater samples) was detected. in addition, no increase in eu concentrations was observed when 2�10 ppb of ba was table 1 measured concentrations of trace elements for the certified material (cass-4 and nass-5) (91s, n �3). certified reference material (unit: mg/l) cass-4 nass-5 element reference value this study reference value this study cr 0.1490.02 0.0990.05 0.1190.02 0.0390.03 mn 2.7890.19 2.9190.07 0.9290.06 1.2490.16 fe 0.7190.06 0.5090.10 0.3090.04 0.6590.10 co 0.0390.00 0.0390.01 0.0190.00 0.0190.01 ni 0.3190.03 0.3490.08 0.2590.03 0.2790.07 cu 0.5990.06 0.7090.03 0.3090.04 0.5090.13 zn 0.3890.06 0.2190.25 0.1090.04 0.0590.2 cd 0.0390.00 0.0290.02 0.0290.00 0.0290.01 pb 0.0190.00 0.0290.04 0.0190.01 0.0190.00 fe, trace elements and rare earth elements from melting glaciers i. kim et al. 4 (page number not for citation purpose) citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 added to the actual samples. these findings indicate that polyatomic interferences of bao or baoh � for eu did not occur in this study. analyses of nutrients and doc to analyse nutrients (din, dip and dsi), approximately 100 ml water samples was filtered through pre-combusted gf/f filters (whatman, kent, uk) and stored frozen in acid-washed 125 ml hdpe bottles (nalgene, rochester, ny, usa). in the laboratory, nutrients were measured using a futura plus auto-analyser (alliance instruments, frepillon, france), which uses the cu�cd reduction column method for din and the molybdenum blue colorimetric method for dip (gordon et al. 1993). in addition, the certified reference material from moos-1 (national research council, canada) was measured in each batch of the samples. for doc analyses, approximately 30 ml water samples was filtered through pre-combusted whatman gf/f filters and acidified with 6 m hcl. the doc samples were then heated in pre-combusted amber glass bottles (5508c for 5 h). a vcph toc analyser (shimadzu, kyoto, japan) was used for the high-temperature combustion oxidation (htco) analysis of doc (dittmar et al. 2006). the detection limit was b5 mm. the accuracy was verified daily using a certified doc seawater sample (deep seawater reference; 46�47 mm) obtained from the university of miami. our results were within 5% of the reference value. results and discussion concentrations of trace elements, nutrients and doc in ice and snow the concentrations of trace elements (al, cr, mn, fe, co, ni, cu, zn, cd, pb, and rees) in ice or snow were one to two orders of magnitude higher than those in seawater, whereas the concentrations of din, dip, dsi and doc in ice or snow were similar to, or much lower than, those in seawater (tables 2, 3). difference in fe concentrations between ice and seawater was the largest: the concentrations of the total dissolved fe in marian cove seawater were in the range of 0.1�3.8 nm (average 1.291.4 nm, n �8), while the concentrations of fe in ice and snow samples were in the range of 2.1�38.1 nm (average 14914 nm, n �5) and 2.6�29.2 nm (average 11911 nm, n �5), respectively. these concentrations were within the range of those reported by previous studies for glacier samples, but our values were slightly lower than the average values (1�600 nm, average 33921 nm, n �29) (table 4), which could be related to the different methodologies used, the type of ice sampled (old glacier or recently formed ice) or the spatio-temporal scales investigated. although there were no data for trace elements, table 2 the concentrations of dissolved organic carbon (doc), dissolved inorganic nitrogen (din), phosphorus (dip), silicate (dsi) and trace elements in seawater, glacier floats and snow samples. station no. salinity fe (nm) doc (mm) din (mm) dip (mm) dsi (mm) al (nm) cr (pm) mn (nm) co (pm) ni (nm) cu (nm) zn (nm) cd (pm) pb (pm) seawater mc1 35.0 0.09 40 22 1.1 64 2.1 60 0.06 15 0.51 0.64 0.71 28 79 mc2 34.6 0.15 44 26 1.3 65 2.7 62 0.13 22 0.49 1.5 1.0 28 50 mc3 34.3 0.10 45 24 0.9 100 18 61 0.15 23 0.55 1.1 1.2 27 120 mc4 34.3 0.20 38 22 0.6 136 24 60 0.07 29 0.54 0.02 2.9 35 30 mc5 33.3 1.11 52 27 4.8 106 6.4 66 0.54 61 0.62 0.02 2.7 27 48 mc6 31.1 2.99 44 23 0.7 59 33 97 0.57 77 0.60 0.13 2.0 25 120 mc7 32.0 3.76 45 23 2.1 61 8.5 84 0.74 110 0.69 0.65 1.0 30 97 mc8 32.6 1.36 43 13 0.4 84 27 63 1.6 73 0.52 0.81 0.94 20 66 floating iceberg 1 0 13.7 20 5.5 0.5 1.3 11 116 223 1030 3.92 2.2 28 26 920 2 0 38.1 31 3.5 0.4 1.4 189 241 0.45 73 3.08 8.1 7.7 11 270 3 0 8.6 67 3.1 0.4 1.4 34 182 1.7 35 0.93 2.0 8.4 5.7 410 4 0 8.1 43 3.3 0.4 1.2 6.2 121 1.9 48 0.73 2.2 8.3 4 190 5 0 2.1 57 2.7 0.4 1.1 3.6 29 0.49 17 0.36 0.72 2.7 2.0 90 snow melts 1 0 12.5 26 6.6 0.2 30 115 59 11 260 1.33 0.87 1.5 13 160 2 0 4.0 31 7.2 0.1 20 102 139 8.0 2450 1.56 5.7 20 12 260 3 0 2.6 44 6.4 0.2 19 331 173 22 6830 4.25 14 20 25 340 4 0 6.1 28 6.2 0.2 18 12 129 3.7 170 0.18 0.82 2.4 4.3 88 5 0 29.2 43 5.7 0.2 32 219 258 17 5280 3.16 12 19 26 550 i. kim et al. fe, trace elements and rare earth elements from melting glaciers citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 the vertical distributions of the nutrients and the doc in the upper layer (b30 m depth) were constant in this region. concentrations of trace elements in seawater: inputs from glacier melting the concentrations of trace elements (al, cr, mn, fe, co, ni, cu, zn, cd, pb and rees) in bay seawater are also listed in tables 2 and 3. the concentrations of most trace elements (al, mn, fe, co, cu, zn, cd, pb and rees) were found to be within the range of those reported from the major oceans (westerlund & öhman 1991; sanudowilhelmy et al. 2002; saito et al. 2010), whereas those of cr and ni were an order of magnitude lower than those in the oligotrophic southern ocean (fitzwater et al. 2000; hendry et al. 2008). in general, cd showed a good correlation with phosphate in the oceans (de baar et al. 1994), with a cd=po 3� 4 ratio (mol:mol) of approximately 0.18 �10�3�0.35 �10�3 (de baar et al. 1994). because the average concentrations of po3�4 in the seawater of this study area were 1.090.5 mm (mostly b1 mm), the relatively lower concentrations of cd (10�100 nm) in this study could be related to biological removal occurring in the surface layer (as shown by hendry et al. 2008) in the antarctic region. as such, löscher (1999) reported table 3 the concentrations of dissolved rare earth elements (ree) in seawater, glacier floats and snow samples. ree (pm) station no. y la ce pr nd sm eu gd tb dy ho er yb lu seawater mc1 16.3 4.9 5.1 0.9 4.4 0.9 0.2 1.0 0.2 0.9 0.20 0.65 0.61 0.11 mc2 19.9 8.0 10.2 1.4 6.5 1.4 0.3 1.5 0.2 1.3 0.27 0.83 0.72 0.11 mc3 13.1 4.9 4.6 0.7 3.6 0.7 0.2 0.8 0.1 0.7 0.17 0.55 0.50 0.08 mc4 16.6 6.4 7.9 1.2 5.6 1.2 0.3 1.4 0.2 1.2 0.24 0.76 0.66 0.10 mc5 23.0 12.1 19.3 2.7 12.6 2.4 0.6 2.6 0.3 1.7 0.33 0.99 0.77 0.12 mc6 21.3 17.6 31.2 3.5 16.2 3.3 0.8 3.5 0.4 2.2 0.41 1.20 0.91 0.13 mc7 39.6 18.4 36.3 5.0 22.2 4.6 1.0 4.7 0.6 3.0 0.57 1.64 1.23 0.18 mc8 22.6 10.7 21.1 2.9 13.1 2.7 0.6 2.8 0.3 1.8 0.34 0.95 0.70 0.10 floating iceberg 1 827 215 435 41 136 31 9.0 35 9.6 34 13 34 24 6.1 2 14.6 9.9 19.7 2.7 12.5 3.0 0.9 2.8 0.4 2.0 0.33 0.92 0.66 0.10 3 4.3 3.2 5.1 0.7 4.0 0.8 0.2 0.8 0.1 0.5 0.10 0.28 0.21 0.02 4 4.9 3.6 5.1 0.7 3.3 0.7 0.2 0.8 0.1 0.5 0.10 0.29 0.20 0.03 5 2.1 1.5 1.8 0.2 1.2 0.3 0.1 0.3 0.0 0.2 0.04 0.12 0.08 0.01 snow melts 1 66 102 36 38 176 47 15 53 8.9 50 8.8 23 15 2.0 2 335 58 141 23 118 35 11 44 6.9 39 6.9 18 12 1.6 3 1090 187 482 76 382 114 36 139 23 130 23 59 41 5.1 4 21 4.1 9.1 1.5 8.1 2.3 0.7 3.0 0.4 2.6 0.5 1.2 0.8 0.1 5 719 128 313 50 254 74 23 93 15 84 15 39 27 3.4 table 4 dissolved fe concentrations in glacier samples. region (sampling year) location sample type fe (nm) weddell sea (2008�2009)a 61�638s, 48�528w floating ice 3.8�28.8 (13912)b gerlache strait (apr 1989)c 64.98s, 63.18w floating ice 25.9 polar frontal region of weddell sea gyre (1992) d 478s to 598s, 68w floating ice 20.4 ice core 10.8�26.3 (19911) seymour island, weddell sea e 64.38s, 56.88w floating iceberg 0.2�0.7 (0.490.3) admiralty strait off king george islande 62.28s, 58.88 iceberg 0.2�2.2 (1.291.4) taylor glacier and canada glacier e 77.6�77.78s, 162�1638e glacier 0.1�3.8 (1.591.8) southern branch of antarctic circumpolar current region (1992)f 52�588s, 68w floating ice 30 law dome, wilkes land (1983) g 66.18s, 110.88e ice core (bhc1) 120 law dome, wilkes land (1988)g 66.78s, 113.28e ice core (de08) 0.5�7.9 (2.992.7) law dome, wilkes land (1993) g 66.78s, 112.88e ice core (dss) 0.6�2.5 (1.290.7) marian cove, king george island, barton peninsula (2012)h 62.28s, 58.88e floating ice 2.1�38.1 (14914) a lin et al. (2011). b one abnormally high value (fe: 607 nm) is excluded when calculating average concentration. c martin (1990). d löscher et al. (1997). e raiswell et al. (2008). f de baar et al. (1995). g edwards et al. (1998). h this study. fe, trace elements and rare earth elements from melting glaciers i. kim et al. 6 (page number not for citation purpose) citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 that the concentrations of ni in seawater have positive relationship with major nutrients (especially phosphate). therefore, we think that the relatively lower concentrations of cr, ni, and cd, which are generally known as nutrientlike elements, in our study region could be associated with larger biological removal during the austral summer. the concentrations of trace elements (al, cr, mn, fe, co, ni, pb and rees) in seawater showed significant negative relationships with salinities (figs. 2, 3). the salinities of seawater decreased from 35.0 to 31.0 at locations near a huge ice valley and at coastal beaches where a large volume of gmw discharges into the sea. when extrapolating the linear plot to a zero salinity by assuming the conservative mixing of dissolved fe in gmw and particles in coastal water, the dissolved fe concentration was determined to be about 2793 nm, which represents the dissolved fe endmember of all fresh gmw entering into the bay (fig. 2). khim et al. (1997) estimated that the freshwater in this region is almost exclusively derived from gmw (d 18 o � �44) during the summer, based on the relationship between d 18 o and salinity. all the isotopic data for marian cove were distributed along the line of mixing between isotopically lighter freshwater and isotopically heavier saline seawater. this endmember is therefore likely to be a representative value of dissolved fe in the gmw in this region. endmembers of gmw-derived fe and other trace elements in seawater this endmember concentration of dissolved fe falls into the range of that in the ice (2.1�38.1 nm) and snow (2.6�29.2 nm) samples collected in the same region but slightly higher than the average values (14914 nm, n �5 for ice; 11911 nm, n �5 for snow). liu & millero (2002) reported that the solubility of fe in seawater could be increased by up to 60% (0.25�0.4 nm) than that 60 10 300 250 200 150 100 50 0 8 6 4 2 0 50 60 80 40 20 0 0 c o n ce n tr a tio n ( p m ) c o n ce n tr a tio n ( p m ) c o n ce n tr a tio n ( u m ) c o n ce n tr a tio n ( p m ) y=–0.95x+77 y=0.72x–1.32 din mn cr (r2=0.10, p=0.07) (r2=0.31, p=0.12) y=–4800x+173900 (r2=0.46, p=0.015) y=–33x+1600 (r2=0.82, p=0.001) co y=–22x+770 (r2=0.23, p=0.16) y=–11x+450 (r2=0.02, p=0.64) y=–770x+26700 al fe (r2=0.96, p<0.001) (r2=0.14, p<0.42) y=170x+6200 y=–8.7x+360 (r2=0.80, p=0.005) (r2=0.78, p=0.001) 100x103 80x103 60x103 40x103 20x103 0 (r2=0.05, p=0.53) y=–0.05x+3.23 (r2=0.002, p=0.80) y=–2.4x+168 ds i (r2=0.02, p=0.48) dipdoc 40 30 20 10 5000 4000 3000 2000 1000 3000 ni 8000 6000 4000 2000 0 2000 1000 0 0 2000 1500 1000 500 0 200 150 100 50 0 200 150 100 50 0 200 150 100 50 0 1000 cu pb cd 800 600 400 200 0 y=–76x+4080 (r2=0.14, p=0.80) y=1.1x–10 zn 50 40 30 20 10 0 y=144x–4200 30 31 32 33 34 35 salinity 36 30 31 32 33 34 35 salinity 36 30 31 32 33 34 35 salinity 36 30 31 32 33 34 35 salinity 36 fig. 2 plots of salinity versus dissolved organic carbon (doc), dissolved inorganic nitrogen (din), phosphorus (dip) and silicate (dsi), and trace elements in marian cove surface water. i. kim et al. fe, trace elements and rare earth elements from melting glaciers citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 in freshwater due to higher ionic strengths. in addition, thuróczy et al. (2012) suggested that the presence of organic ligands could also increase the solubility of fe in seawater. the fe endmember that is higher than the fe concentration in ice is therefore considered to be related to the additional fe released from particles in ice and shallow sediments. the fe concentrations in our ice samples are within the range of those reported by previous studies for glacier samples, but slightly lower than the average values (1� 600 nm, mean �33921 nm, n �29; table 4). although lin et al. (2011) did not quantify the fe inputs from glacier melting water and particles, they observed the relationship between fe and salinity in the weddell sea, indicating the fe concentration of gmw to be 45913 nm. these discrepancies are considered to be related to the large differences in the methodologies, the type of ice samples (old glacier or recently formed ice), and the spatio-temporal scales sampling. our endmember value could be slightly underestimated owing to various fe sinks such as phytoplankton uptake, settling, and scavenging, although fe shows a strong negative correlation with salinity. we also estimated the endmember concentrations of other trace elements in ice samples using the same method. the extrapolated endmember concentrations of al, mn, cr, ni, co and pb were 174995 nm, 6.191.3 nm, 0.3690.06 nm, 1.790.5 nm, 0.7790.14 and 0.4590.28 nm, respectively. although trace elements data in glacial ice are scarce, we compare our endmember concentrations to those in ice core samples. our endmembers of cr (360960 pm) and pb (4509280 pm) were similar to, or significantly higher than, those of previously reported values (180�710 pm for cr and 0.070�12 nm for pb from dome c and the low dome ice core, respectively; boutron et al. 1994; gabrielli et al. 2005). the endmember of al in our study was estimated to be 174 nm, which is one to two orders of magnitude higher than that in the low dome ice core (hong et al. 1998). this difference is likely due to the different types of ice samples and spatio-temporal variations. influence of gmw-driven trace element fluxes on their inventories in seawater if we assume that the average salinity in marian cove is 33, the amount of gmw in the surface waters (b30 m depth) of marian cove is estimated to be approximately 7.2 �106 m3. assuming that the average salinity in marian cove is 33, we calculated the contribution of c o n ce n tr a tio n ( p m ) c o n ce n tr a tio n ( p m ) c o n ce n tr a tio n ( p m ) y= –3.2x+115 (r 2 =0.87, p=0.07) y= –0.7x+25 sm (r 2 =0.87, p=0.002) y= –0.34x+12.8 (r 2 =0.83, p=0.003) y= –0.06x+2.16 (r 2 =0.81, p=0.003) y= –0.07x+3.1 (r 2 =0.60, p=0.02) y= –0.007x+3.35 (r 2 =0.38, p=0.05) ludy ho y= –0.15x+5.4 eu (r 2 =0.88, p=0.001) y= –0.7x+25.9 tbgd (r 2 =0.89, p=0.001) y= –0.08x+2.8 (r 2 =0.86, p=0.002) y= –7.0x+249 (r 2 =0.93, p<0.001) y= –0.75x+27 (r 2 =0.87, p=0.002) y= –3.4x+128 (r 2 =0.87, p=0.002)pr nd yb la ce 25 50 40 30 20 10 0 20 15 10 5 0 10 30 25 20 15 10 5 0 8 6 4 2 0 10 8 6 4 2 0 10 8 6 4 2 0 2.0 1.5 1.0 0.5 0.0 2.0 1.5 1.0 0.5 0.0 1.0 0.6 0.8 0.4 0.2 0.0 0.4 0.3 0.2 0.1 0.0 1.0 0.6 0.8 0.4 0.2 0.0 5 4 3 2 1 0 30 31 32 33 34 35 salinity 36 30 31 32 33 34 35 salinity 36 30 31 32 33 34 35 salinity 36 30 31 32 33 34 35 salinity 36 fig. 3 plots of salinity versus rare earth elements in marian cove surface water. fe, trace elements and rare earth elements from melting glaciers i. kim et al. 8 (page number not for citation purpose) citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 gmw in the inventory of trace elements in marian cove, based on the correlations with salinity. the calculated average concentrations of these elements in cove water were thus increased by approximately eight-fold for al, 1.2-fold for cr, 10-fold for mn, 18-fold for fe, four-fold for co, 1.2-fold for ni, 2.9-fold for pb, and 1.9-fold for rees, relative to the background seawater (with no gmw input) (fig. 4). in contrast, we did not find any appreciable inputs of cu, cd, nutrients (din, dip and dsi), and doc from gmw to the bay water (ratios 51, fig. 4) as predicted from the lower concentrations of these chemical components in ice/snow samples than in seawater. the calculated average fe concentration enhanced by gmw input was about 1.6 nm (fig. 4), which was much higher than that in the background seawater concentration (0.09 nm fe with no gmw input). considering that the fraction of fresh glacier melts (7.2 �106 m3) accounts for only about 5.7% of the total marian cove surface water (1.2 �108 m3), the impact of gmw to the fe inventory is striking. our calculations covered the trace element budgets of the entire cove area resulting from glacial melts and dissolution from (glacial) particles. these results suggest that antarctic glacier melting has a significant influence on the budgets of trace elements (particularly fe). rees as tracers of gmw-derived trace elements as evidence of terrestrial source inputs for rees, we found a substantial elevation of mree in the bay seawater when normalized for the upper continental crust (taylor & mclennan 1985). this mree enrichment, relative to the typical ocean pattern (elderfield et al. 1990; nozaki et al. 2000), is evidently related to glacier melting as there was a strong relationship between salinity and rees (fig. 3). the mree enrichment pattern was even clearer in beach seawater samples (fig. 5). all our ice floats and snow exhibited mree enrichment, which could be from patagonian origin because this pattern resembles those from volcanic rocks sampled in that region (gaiero et al. 2004) and/or those shown by south american dust (gabrielli et al. 2010). implication: gmw as a source of fe in the southern ocean although a large fraction of fe supplied into the coastal ocean probably settles to bottom sediments before being utilized by phytoplankton, fe adsorbed onto sediments can be returned to the water column around the antarctic peninsula through sedimentary diagenesis or re-suspension (de jong et al. 2013). this remobilized fe can also be transported to offshore regions through lateral water mixing. previous studies (dulaiova et al. 2009; ardelan et al. 2010) showed that the transport of the antarctic shelf-water to the southern ocean is an important mechanism for fe delivery to the offshore region. for example, dulaiova et al. (2009) reported that the fe flux through lateral transport to the drake passage is 4.0 �107 mol fe yr�1, which is much larger than the vertical flux of dust-borne fe. ardelan et al. (2010) also suggested that this supply of fe by lateral transport contributes significantly to high phytoplankton biomass in the scotia sea region. more recently, de jong et al. (2012) showed that almost a half (54%) of the total fe flux to the atlantic sector of the southern ocean is transported through horizontal advection. recent studies have also shown that global warming may have caused an increase in the disintegration of the ice shelves along the antarctic peninsula by up to 13% during the last two decades (rignot et al. 2011). our results imply that the increase of fe in association with glacier melting may enhance the future biological productivity of the southern ocean. conclusions this study found that the inventories of some trace elements (al, fe, mn, cr, ni, co, pb, and rees) in seawater were increased up to 18-fold in marian cove, antarctica (628s), by gmw inputs. the gmw inputs resulted in substantially higher mree in seawater, a pattern indicative of terrestrial source inputs. our results imply that the 20 18 16 14 12 10 8 6 4 2 0 al cr mn fe ce ni cu zn cd pb ree din dip dsi doc c o n ce n tr a tio n ra tio ( a vg ./ b kg .) fig. 4 ratios of calculated average (avg.) concentrations of trace elements, rare earth elements (ree), dissolved inorganic nitrogen (din), phosphorus (dip), silicate (dsi) and dissolved organic carbon (doc) in marian cove surface water to those in background seawater, with no glacier melts (bkg.). the value for ree is the average of all elements since they showed a similar trend. i. kim et al. fe, trace elements and rare earth elements from melting glaciers citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 modern rates of glacier/ice melting in antarctica may contribute significantly to the budgets of trace elements in coastal seawater. further extensive studies are necessary in order to quantify the fluxes of trace elements, particularly fe, caused by gmw transport to the polar oceans and to evaluate the biogeochemical consequences of such fluxes to the ocean require further investigation. acknowledgements we are grateful to three anonymous reviewers for providing insightful comments and suggestions that improved this manuscript. we also thank all workers at the korea polar research institute and the korean antarctic research base, king sejong, who helped with field work and sampling. this work was supported by a national research foundation of korea grant funded by the korean government (nrf-2013r1a2a1a05004343) and a grant from the korea polar research institute for the project titled impacts of ocean acidification on calcifying organisms in the antarctic marine ecosystem (pe14150). ik was supported by scholarships from bk21. references ahn i.y., chung h., kang j.s. & kang s.h. 1997. diatom composition and biomass variability in nearshore waters of maxwell bay, antarctica, during the 1992/1993 austral summer. polar biology 17, 123�130. alderkamp a.c., mills m.m., van dijken g.l., laan p., thuróczy c.e., gerringa l.j.a., de baar h.j.w., payne c.d., visser r.j.w. & buma a.g.j. 2012. iron from melting glaciers fuels phytoplankton blooms in the amundsen sea (southern ocean): phytoplankton characteristics and productivity. deep-sea research part ii 71, 32�48. ardelan m.v., holm-hansen o., hewes c.d., reiss c.s., silva n.s., dulaiova h., steinnes e. & sakshaug e. 2010. natural iron enrichment around the antarctic peninsula in the southern ocean. biogeosciences 7, 11�25. bhatia m.p., kujawinski e.b., das s.b., breier c.f., henderson p.b. & charette m.a. 2013. greenland meltwater as a significant and potentially bioavailable source of iron to the ocean. nature geoscience 6, 274�278. bindschadler r. & rignot e. 2001. ‘‘crack!’’ in the polar night. eos, transactions of the american geophysical union 82, 497�505. boutron c.f., candelone j.p. & hong s. 1994. past and recent changes in the large-scale tropospheric cycles of lead and other heavy metals as documented in antarctic and 1 0.1 0.01 (s a m p le /u c c )x 1 0 6 (s a m p le /u c c )x 1 0 6 0.001 0.01 1 0.1 0.01 1 0.1 0.010.001 floating ice snow melts beach seawaterbay seawater mc1 mc2 mc3 mc4 1 2 3 4 5 1 2 3 4 5 la ce pr nd eusm gd dy ho er tm yb lutb la ce pr nd eusm gd dy ho er tm yb lutb la ce pr nd eusm gd dy ho er tm yb lutb la ce pr nd eusm gd dy ho er tm yb lutb mc1 mc2 mc3 mc4 mc5 mc6 mc7 mc8 10 1 0.1 fig. 5 upper continental crust (ucc)-normalized rare earth element patterns in ice, snow and seawater (beach seawater � bay water) samples from marian cove. fe, trace elements and rare earth elements from melting glaciers i. kim et al. 10 (page number not for citation purpose) citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 greenland snow and ice: a review. geochimica et cosmochimica acta 58, 3217�3225. buma a.g.j., de baar h.j.w., nolting r.f. & van bennekom a.j. 1991. metal enrichment experiments in the weddell� scotia seas: effects of iron and manganese on various plankton communities. limnology and oceanography 36, 1865�1878. coale k.h., wang x., tanner s.j. & johnson k.s. 2003. phytoplankton growth and biological response to iron and zinc addition in the ross sea and antarctic circumpolar current along 170 w. deep-sea research part ii 50, 635�653. cook a.j. & vaughan d.g. 2009. overview of areal changes of the ice shelves on the antarctic peninsula over the past 50 years. the cryosphere discussions 3, 579�630. de baar h.j.w., de jong j.t.m., bakker d.c.e., löscher b.m., veth c., bathmann u. & smetacek v. 1995. importance of iron for plankton blooms and carbon dioxide drawdown in the southern ocean. nature 373, 412�415. de baar h.j.w., saager p.m., nolting r.f. & van der meer j. 1994. cadmium versus phosphate in the world ocean. marine chemistry 46, 261�281. de jong j., schoemann v., lannuzel d., croot p., de baar h. & tison j.l. 2012. natural iron fertilization of the atlantic sector of the southern ocean by continental shelf sources of the antarctic peninsula. journal of geophysical research* biogeosciences 117, g01029, doi: 10.1029/2011jg001679. de jong j., schoemann v., maricq n., mattielli n., langhorne p., haskell t. & tison j.l. 2013. iron in land-fast sea ice of mcmurdo sound derived from sediment resuspension and wind-blown dust attributes to primary productivity in the ross sea, antarctica. marine chemistry 157, 24�40. dittmar t., hertkorn n., kattner g. & lara r.j. 2006. mangroves, a major source of dissolved organic carbon to the oceans. global biogeochemical cycles 20, gb1012, doi: 10.1029/2005gb002570. dulaiova h., ardelan m., henderson p.b. & charette m.a. 2009. shelf-derived iron inputs drive biological productivity in the southern drake passage. global biogeochemical cycles 23, gb4014, doi: 10.1029/2008gb003406. edwards r., sedwick p.n., morgan v., boutron c.f. & hong s. 1998. iron in ice cores from law dome, east antarctica: implications for past deposition of aerosol iron. annals of glaciology 27, 365�370. elderfield h., upstill-goddard r. & sholkovitz e.r. 1990. the rare earth elements in rivers, estuaries, and coastal seas and their significance to the composition of ocean waters. geochimica et cosmochimica acta 54, 971�991. fitzwater s., johnson k., gordon r., coale k. & smith w. jr. 2000. trace metal concentrations in the ross sea and their relationship with nutrients and phytoplankton growth. deep-sea research part ii 47, 3159�3179. gabrielli p., barbante c., boutron c., cozzi g., gaspari v., planchon f., ferrari c., turetta c., hong s. & cescon p. 2005. variations in atmospheric trace elements in dome c (east antarctica) ice over the last two climatic cycles. atmospheric environment 39, 6420�6429. gabrielli p., wegner a., petit j.r., delmonte b., de deckker p., gaspari v., fischer h., ruth u., kriews m. & boutron c. 2010. a major glacial�interglacial change in aeolian dust composition inferred from rare earth elements in antarctic ice. quaternary science reviews 29, 265�273. gaiero d.m., depetris p.j., probst j.l., bidart s.m. & leleyter l. 2004. the signature of riverand wind-borne materials exported from patagonia to the southern latitudes: a view from rees and implications for paleoclimatic interpretations. earth and planetary science letters 219, 357�376. gerringa l.j.a., alderkamp a.c., laan p., thuroczy c.e., de baar h.j.w., mills m.m., van dijken g.l., van haren h. & arrigo k.r. 2012. iron from melting glaciers fuels the phytoplankton blooms in amundsen sea (southern ocean): iron biogeochemistry. deep-sea research part ii 71, 16�31. gordon l.i., jennings j.c. jr., ross a.a. & krest j.m. 1993. a suggested protocol for continuous flow automated analysis of seawater nutrients (phosphate, nitrate, nitrite and silicic acid) in the woce hydrographic program and the joint global ocean fluxes study. methods manual whpo91�1. corvallis, or: world ocean circulation experiment hydrographic program office, oregon state university. hendry k.r., rickaby r.e., de hoog j., weston k. & rehkämper m. 2008. cadmium and phosphate in coastal antarctic seawater: implications for southern ocean nutrient cycling. marine chemistry 112, 149�157. hong s., boutron c.f., edwards r. & morgan v.i. 1998. heavy metals in antarctic ice from law dome: initial results. environmental research 78, 94�103. jacobs s.s., jenkins a., giulivi c.f. & dutrieux p. 2011. stronger ocean circulation and increased melting under pine island glacier ice shelf. nature geoscience 4, 519�523. jeong j., kim g. & han s. 2012. influence of trace element fluxes from submarine groundwater discharge (sgd) on their inventories in coastal waters off volcanic island, jeju, korea. applied geochemistry 27, 37�43. khazendar a., schodlok m.p., fenty i., ligtenberg s.r.m., rignot e. & van den broeke m.r. 2013. observed thinning of totten glacier is linked to coastal polynya variability. nature communications 4, article no. 2857, doi: 10.1038/ ncomms3857. khim b.k., park b.k. & yoon h.i. 1997. oxygen isotopic compositions of seawater in the maxwell bay of king george island, west antarctica. geosciences journal 1, 115�121. kim i. & kim g. 2011. large fluxes of rare earth elements through submarine groundwater discharge (sgd) from a volcanic island, jeju, korea. marine chemistry 127, 12�19. klöser h., ferreyra g., schloss i., mercuri g., laturnus f. & curtosi a. 1993. seasonal variation of algal growth conditions in sheltered antarctic bays: the example of potter cove (king george island, south shetlands). journal of marine systems 4, 289�301. lee j.m., boyle e.a., echegoyen-sanz y., fitzsimmons j.n., zhang r. & kayser r.a. 2011. analysis of trace metals (cu, cd, pb, and fe) in seawater using single batch i. kim et al. fe, trace elements and rare earth elements from melting glaciers citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 nitrilotriacetate resin extraction and isotope dilution inductively coupled plasma mass spectrometry. analytica chimica acta 686, 93�101. lewis b.l. & landing w.m. 1991. the biogeochemistry of manganese and iron in the black sea. deep-sea research part a 38, s773�s803. lin h., rauschenberg s., hexel c.r., shaw t.j. & twining b.s. 2011. free-drifting icebergs as sources of iron to the weddell sea. deep-sea research part ii 58, 1392�1406. liu x. & millero f.j. 2002. the solubility of iron in seawater. marine chemistry 77, 43�54. long d.g., ballantyn j. & bertoia c. 2002. is the number of antarctic icebergs really increasing? eos, transactions of the american geophysical union 83, 469�474. löscher b.m. 1999. relationships among ni, cu, zn, and major nutrients in the southern ocean. marine chemistry 67, 67�102. löscher b.m., de baar h.j.w., de jong j.t.m., veth c. & dehairs f. 1997. the distribution of fe in the antarctic circumpolar current. deep-sea research part ii 44, 143�187. luckman a., padman l. & jansen d. 2010. persistent iceberg groundings in the western weddell sea, antarctica. remote sensing of environment 114, 385�391. maher b.a. & dennis p.f. 2001. evidence against dustmediated control of glacial�interglacial changes in atmospheric co2. nature 411, 176�180. martin j.h. 1990. glacial-interglacial co2 change: the iron hypothesis. paleoceanography 5, 1�13. milne a., landing w., bizimis m. & morton p. 2010. determination of mn, fe, co, ni, cu, zn, cd and pb in seawater using high resolution magnetic sector inductively coupled mass spectrometry (hr-icp-ms). analytica chimica acta 665, 200�207. nozaki y., lerche d., alibo d.s. & tsutsumi m. 2000. dissolved indium and rare earth elements in three japanese rivers and tokyo bay: evidence for anthropogenic gd and in. geochimica et cosmochimica acta 64, 3975�3982. öztürk m. 1995. trends of trace metal (mn, fe, co, ni, cu, zn, cd and pb) distributions at the oxic�anoxic interface and in sulfidic water of the drammensfjord. marine chemistry 48, 329�342. öztürk m., bizsel n. & steinnes e. 2003. iron speciation in eutrophic and oligotrophic mediterranean coastal waters; impact of phytoplankton and protozoan blooms on iron distribution. marine chemistry 81, 19�36. pritchard h.d., ligtenberg s.r.m., fricker h.a., vaughan d.g., van den broeke m.r. & padman l. 2012. antarctic ice-sheet loss driven by basal melting of ice shelves. nature 484, 502�505. raiswell r. 2011. iceberg-hosted nanoparticulate fe in the southern ocean: mineralogy, origin, dissolution kinetics and source of bioavailable fe. deep-sea research part ii: topical studies in oceanography 58, 1364�1375. raiswell r., benning l.g., tranter m. & tulaczyk s. 2008. bioavailable iron in the southern ocean: the significance of the iceberg conveyor belt. geochemical transactions 9, 7, doi: 10.1186/1467-4866-9-7. rignot e., jacobs s., mouginot j. & scheuchl b. 2013. ice-shelf melting around antarctica. science 341, 266�270. rignot e. & steffen k. 2008. channelized bottom melting and stability of floating ice shelves. geophysical research letters 35, article no. 7, doi: 10.1029/2007gl031765. rignot e. & thomas r.h. 2002. mass balance of polar ice sheets. science 297, 1502�1506. rignot e., velicogna i., van den broeke m.r., monaghan a. & lenaerts j. 2011. acceleration of the contribution of the greenland and antarctic ice sheets to sea level rise. geophysical research letters 38, l05503, doi: 10.1029/ 2011gl046583. saito m.a., goepfert t.j., noble a.e., bertrand e.m., sedwick p.n. & ditullio g.r. 2010. a seasonal study of dissolved cobalt in the ross sea, antarctica: micronutrient behavior, absence of scavenging, and relationships with zn, cd, and p. biogeosciences 7, 4059�4082. sanudo-wilhelmy s., olsen k., scelfo j., foster t. & flegal a. 2002. trace metal distributions off the antarctic peninsula in the weddell sea. marine chemistry 77, 157�170. scambos t.a., hulbe c., fahnestock m. & bohlander j. 2000. the link between climate warming and break-up of ice shelves in the antarctic peninsula. journal of glaciology 46, 516�530. schodlok m.p., hellmer h.h., rohardt g. & fahrbach e. 2006. weddell sea iceberg drift: five years of observations. journal of geophysical research*oceans 111, article no. c06018, doi: 10.1029/2004jc002661. schwarz j.n. & schodlok m.p. 2009. impact of drifting icebergs on surface phytoplankton biomass in the southern ocean: ocean colour remote sensing and in situ iceberg tracking. deep-sea research part i 56, 1727�1741. shaw t.j., raiswell r., hexel c.r., vu h.p., moore w.s., dudgeon r. & smith k.r. jr. 2011. input, composition, and potential impact of terrigenous material from free-drifting icebergs in the weddell sea. deep-sea research part ii 58, 1376�1383. shim j.g., kang y.c., kang d.j. & han m.w. 2011. fluxes and budgets of biogenic elements at the sediment�water interface of marian cove, king george island. antarctic science 1, 1�11. smith k.l. jr., robison b.h., helly j.j., kaufmann r.s., ruhl h.a., shaw t.j., twining b.s. & vernet m. 2007. free-drifting icebergs: hot spots of chemical and biological enrichment in the weddell sea. science 317, 478�482. statham p.j., skidmore m. & tranter m. 2008. inputs of glacially derived dissolved and colloidal iron to the coastal ocean and implications for primary productivity. global biogeochemical cycles 22, gb3013, doi: 10.1029/2007gb 003106. sunda w.g. & huntsman s.a. 1997. interrelated influence of iron, light and cell size on marine phytoplankton growth. nature 390, 389�392. taylor s.r. & mclennan s.m. 1985. the continental crust: its composition and evolution. oxford: blackwell scientific. thuróczy c.e., alderkamp a.c., laan p., gerringa l.j., mills m.m., van dijken g.l., de baar h.j.w. & arrigo k.r. 2012. fe, trace elements and rare earth elements from melting glaciers i. kim et al. 12 (page number not for citation purpose) citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 key role of organic complexation of iron in sustaining phytoplankton blooms in the pine island and amundsen polynyas (southern ocean). deep-sea research part ii 71, 49�60. velicogna i. & wahr j. 2006. measurements of time-variable gravity show mass loss in antarctica. science 311, 1754�1756. westerlund s. & öhman p. 1991. cadmium, copper, cobalt, nickel, lead, and zinc in the water column of the weddell sea, antarctica. geochimica et cosmochimica acta 55, 2127�2146. williams r.n., rees w.g. & young n.w. 1999. a technique for the identification and analysis of icebergs in synthetic aperture radar images of antarctica. international journal of remote sensing 20, 3183�3199. yoo k.c., yoon h.i., oh j.k., kang c.y. & khim b.k. 2000. water column structure and dispersal pattern of suspended particulate matter (spm) in a floating ice-dominated fjord. marian cove, antarctica during austral summer. the sea 5, 295�304. yoon h.i., park b.k., domack e.w. & kim y. 1998. distribution and dispersal pattern of suspended particulate matter in maxwell bay and its tributary, marian cove, in the south shetland islands, west antarctica. marine geology 152, 261�275. i. kim et al. fe, trace elements and rare earth elements from melting glaciers citation: polar research 2015, 34, 24289, http://dx.doi.org/10.3402/polar.v34.24289 13 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24289 http://dx.doi.org/10.3402/polar.v34.24289 book review book review review of five journeys through the arctic and a new russia in search of willem barents, by jaapjan zeeberg (2023). soesterberg, netherlands: aspekt publishers. 372 pp. isbn 978-9-46462-914-9.   citation: polar research 2023, 42, 9739, http://dx.doi.org/10.33265/polar.v42.9739 copyright: © 2023 susan barr. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 10 july 2023 correspondence susan barr, snarøya, norway. e-mail: snbarr@gmail.com   there are a number of decidedly iconic cultural heritage sites in the high arctic that are connected with european exploration in the 16th to 19th centuries. many of these were protected from serious human impact up to the late 20th century when climate change and increasing access possibilities opened up the area. one such site is the remains of willem barentsz’ wintering house on the north-eastern tip of novaya zemlya. this was in addition protected by visitor restrictions to the area during the soviet union period. after the break-up of the soviet union, the 1990s offered a window of opportunity for western scientists to approach the site and investigate the remains of the wintering house known as het behouden huys (the preserved/remained house). the stated aim of this book by jaapjan zeeberg is to present the dutch–russian expeditions to novaya zemlya in 1991, 1993, 1995, 1998, and 2000 that were intended both to document the house site and to search for remains of barentsz’ ship and his grave. curiously enough, one of the most important of such expeditions occurred in 1992 and is passed over in complete silence in zeeberg’s account. willem barentsz (1550–1597; zeeberg uses the anglicised name barents, which is less usual now) was a dutch navigator who was sent on three expeditions from the netherlands to search for a north-east passage from europe to asia. in 1594, the expedition met favourable ice conditions and reached as far east as novaya zemlya and the kara sea. the following year, the vaigatch strait was blocked by ice. the final expedition in 1596 is the most famous owing to the first recorded discovery of western svalbard and the unfortunate trapping of barentsz’ ship in the ice off northern novaya zemlya. barentsz, who was the navigator and cartographer, captain jacob van heemskerk, and the 14-man crew built a wintering house of drift logs and wood from the wrecked ship. in june 1597, the group started southwards in two open boats. barentsz died on the 20th, and a burial site has never been found. the wintering became internationally famous through the published diary of crew member gerrit de veer, which was quickly translated into several languages and contains detailed and apparently reliable descriptions of the wintering and escape southwards. norwegian skipper elling carlsen was in 1871 probably the first to discover and certainly to describe the wintering site and to gather artifacts. in 1875 and 1876, two other western visitors collected more artifacts, and in 1933, 1977, 1979, and 1980, russian visits occurred that also documented and collected artifacts. zeeberg’s book describes both the history behind the wintering and the visits and results mentioned above. he himself steps into the picture in the 1990s and his book becomes a mixture of excerpts from his own diaries and from other dutch participants on the expeditions where he was not present. this reviewer is probably biased with regard to the day-by-day diary entries that describe the often spontaneous, sometimes ridiculous, and at times hazardous experiences of traveling to the high arctic with russians during the 1990s. having done it myself, i enjoyed reliving the experiences and could thoroughly visualize the camping, the cold, and the frustrations but also the gratitude for the opportunities to gain access to iconic historical sites on the islands north of the russian mainland. the various diary entries contain evocative descriptions of scenes and events and references to other relevant experiences and comparisons, and they document how much time on such expeditions is wasted on logistics— just arriving at the site can take most of the allotted time. a disadvantage of basing much of the story on diaries is that it can at times be confusing as to whom, what, where, and why. it is not until the final acknowledgments at the end of the book that much of the missing information is revealed, such as surnames for people otherwise referred to by only first names and more of the context of the described expeditions. the final expedition the author undertook was in 2000 to vaigatch island “to see what we could find there” (p. 305) but who his companions were and why they went there is not particularly clear. again, the descriptions from the diary are detailed and interesting, but this expedition seems to have nothing to do with the titled search for willem barents. it resulted in a lot of hanging around waiting for permissions or transport and a final 10 days—described over 18 pages—alone in a soggy tent waiting for the pick-up helicopter. for readers not so interested in daily updates from the tents, the book can feel overly focused on the author’s personal trips to the detriment of analyses and contexts concerning the barentsz site. all in all, the book has interesting qualities, particularly the vivid descriptions of how fieldwork in the russian high arctic in the ‘happy-go-lucky’ period of the 1990s could be—and, according to this reviewer’s own experience, usually was. it also presents an overview of willem barentsz’ expeditions and associated events as well as the history of het behouden huys and its fate after the barentsz expedition left in 1597. this history shows clearly how much the site has been disturbed by human activity since its rediscovery in 1871, the large number of artifacts that have been removed both with and, most often, without professional archaeological recording methods, and how the artifacts have ended up in various museums and institutes. however, it is with regard to this latter history that the book has one large failing that reflects negatively on the rest as a faithful and honest account. this reviewer is well aware of what was perhaps the most professional archaeological study of the barentsz house site and which is well documented, for example, in an article in the peer-reviewed, multidisciplinary, scientific journal arctic, published by the arctic institute of north america in 1995. zeeberg has himself published in arctic concerning the search for barentsz’ grave, so the journal is not unknown to him. nor is it possible to imagine that the distinguished dutch arctic archaeologist and author of the 1995 paper, professor louwrens hacquebord, would be unknown to zeeberg. if the expedition in 1992 that he omits from his history of the site was unknown to him, it would be a hard job to explain why. as he in addition briefly mentions the multi-disciplinary expedition to investigate the dutch whaling station of smeerenburg in svalbard in 1979–81, which was led by hacquebord, it could seem to be a deliberate slight to mangle the latter’s name (“laurens hakbord”). all this is unfortunate as it sabotages the otherwise useful chronology of investigations of the barentsz house site and negatively colors the impression of the book as a whole. the publisher offered only a digital version of the book for review. this saves them money but makes the book project less tangible for the reviewer. in the digital version, pages 260–263 are mixed up. hopefully they are not in the printed book as well. references hacquebord l. 1995. in search of het behouden huys: a survey of the remains of the house of willem barentsz on novaya zemlya. arctic 48, 248–256, doi: 10.14430/arctic1246. no job name b o o k r e v i e w por_136 468..469 review of point hope alaska: life on frozen water, by berit arnestad foote (2009). fairbanks: university of alaska press. 244 pp. isbn 978-1-60223-065-1. this beautifully illustrated book documents three years in the life of point hope, alaska. point hope has been a whaling camp site of the inupiat people for over 2500 years, based on archaeological studies. up until the 1950s, the settlement here had remained much as it had been since its inhabitants first began having contact with outsiders. missionaries, school teachers and supplies had arrived from the usa in the 20th century, as the territory of alaska started to receive greater attention from the government and people of the “lower 48” states. but in the 1950s, two rather momentous events conspired to change point hope, and the rest of rural alaska. in 1959 alaska became the 49th state of the union. one year earlier, the nuclear physicist edward teller proposed to the atomic energy commission (aec) that they explode an atomic bomb 100 times more powerful than the one dropped on hiroshima in north-west alaska, in order to create a man-made harbour. the site selected by the aec was ogotoruk creek, 50 km south-east of point hope. this proposal seems ludicrous to most people in the 21st century. indeed, the author’s brother-in-law, joseph foote, described it as “harebrained but frightening” in his essay near the start of the book. nevertheless, the project was adopted by the aec, under the code name of project chariot. the full story of this bizarre chapter in american history has been very well told in dan o’neill’s book, the firecracker boys (1994). project chariot brought a young american geographer, don foote, and his norwegian wife, berit arnestad foote, to point hope. they formed part of the team of scientists sent to determine the effects of the nuclear blast on the surrounding environment. berit arrived in november 1959, and ended up staying three years at point hope, or tikigaq, as it is called by the indigenous population. this book represents a photographic album of her time there. it presents a fascinating ethnographic study of a people who, at that time, were still maintaining the essential elements of a traditional hunter–gatherer lifestyle. there were no cars or trucks in point hope at that time, and no snowmobiles. transportation was by foot, dog sled or skin boat. winters were spent in flimsy-looking wooden shacks or sod houses. much of the summer was spent in canvas tents. hunting was the primary occupation of the men. the different seasons of the year initiated the hunting of various prey animals, including caribou on land and various marine mammals at sea. but, these people and their ancestors chose to settle at point hope because it offers excellent opportunities to hunt humpback whales. there is very little text in this book. it is almost completely devoted to the author’s photographs. fifty photos are reproduced in colour, and more than a hundred black and white photos are provided. the book itself is in a rather large format: 25 ¥ 28 cm. because the photographs were snapshots taken with an ordinary camera of 1950s vintage, many of them appear quite grainy in these large-format reproductions. however, this does not really detract from the book. in fact, it adds a sort of naive charm. berit foote was not a professional photographer, but if she had been, she probably would not have been given such complete access to photograph the intimate details and daily lives of the inhabitants. therein lies both the beauty and usefulness of this exceptional book. looking at these pictures gives you a set of very vivid impressions of what life was like for the inupiat of point hope at this critical juncture in their history. it quite literally documents their passage from traditional correspondence scott elias, geography department, royal holloway, university of london, egham, surrey, tw20 0ex, uk. e-mail: s.elias@rhul.ac.uk polar research 28 2009 468–469 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd468 mailto:elias@rhul.ac.uk hunter–gatherers into residents of the 49th state of the union. parts of the traditional whale hunting lifestyle remain in point hope and other inupiat villages today, but it will never be the same as it was before contact with people from outside the arctic. the pictures are placed in groups, depicting the different seasons of the year. many of the photographs show how hard the life was. the native people were battling the elements: the bitter cold of winter, and the evershifting pack ice in spring and early summer. they were battling the mighty whales, not from the safety of some modern, iron-clad whaling ship, with cannon-fired harpoons, but from small skin umiaks, using traditional weapons. survival, both of the individual and of the community, was not to be taken for granted. the village had faced starvation only a few decades earlier, as documented by charles brower in his classic book about life in arctic alaska, fifty years below zero (1942). the people had to rely on each other in order to survive. whale hunting involved all the able-bodied men of the community. whale carcass butchering involved all of the adults. this was the fierce, frightening, dangerous side of life at point hope, and it is well documented here. but, there is another side of life, in the home, at clan gatherings and at play. the pictures in this book capture the cosy feel of family life, with kids playing, women sharing chores and men sitting around a fire at a hunting camp. the good humour of these people shines through, time and again. there is much smiling and laughter. there is an indelible mark of community shown here. that small community was galvanized by the threat of destruction brought by project chariot, and they eventually managed to defeat their high-powered foes in washington, d.c.: project chariot was cancelled in 1962. the people of tikigaq founded a native alaskan environmental movement that is still active today, almost 50 years later. ironically, the aec scientists wanted to test their nuclear civil engineering plans in north-west alaska precisely because they thought there was nothing of value there—no one would care what happened. this book documents precisely what would have been destroyed: a fascinating and rich native culture. scott elias references brower c. 1942. fifty years below zero: a lifetime of adventure in the far north. new york: dodd, mead & co. reprinted in 2008, whitefish, mt: kessinger publishing. o’neill d. 1994. the firecracker boys. h-bombs, inupiat eskimos, and the roots of the environmental movement. new york: st. martins press. book review polar research 28 2009 468–469 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 469 low protein variability and genetic similarity between populations of the polar bear (ursus maritimus) t h o r larsen, hakan tegelstrom, r. kumar juneja and mitchell k. taylor larsen, t . , tegelstrom, h . . kumar juneja, r . & taylor, m. k. 1983: low protein variability and genetic similarity between populations of the polar bear (ursus maritimus). polar research 1 n . s . , 97-105. blood samples from a total of 460 polar bears (ursus maritimus) from various arctic regions, but excluding the ussr, were collected during the period 1967-1981 to study electrophoretic variation in different proteins. two hundred and one samples from alaska, 48 from the canadian arctic, 89 from svalbard, and 21 from northeast greenland were collected during the period 1967-1973 and were analysed by vertical polyacrylamide gel electrophoresis to study transferrin and hemoglobin polymorphism, thirty-one samples collected in 1974 were analysed by starch gel electrophoresis for 14 enzyme systems in serum and red blood cells. seventy samples collected from alaska, the barents sea, and canada in 198&81 were studied by starch gel electrophoresis, and further analysed for protein variation by thin-layer isoelectric focusing, horizontal polyacrylamide gel electrophoresis, and two-dimensional electrophoresis. in all, about 75 loci were analysed for variation. the degree of protein and enzyme variation in the polar bear was observed to be relatively low. starch gel electrophoresis revealed variation of an unidentified serum protein. the distribution of this protein indicates a closer connection between bears in alaska and canada compared to those in greenland and svalbard, but the differences were not significant. as in many large mammals, the information from protein variation in polar bears has limited use for management purposes. we could not find any simple system usable for identification of discrete populations. on the basis of protein variation as sole criterion, the populations investigated could not be separated. possible explanations for the uniformity of blood proteins can be exchange of bears between geographical areas and/or a high selective pressure in polar bears. thor larsen, norsk polarinstitun, box 158, n-1330 oslo lufthaun, norway; hdkan tegelstrom, department of genetics, university of uppsala, box 7003, s-75 007 uppsala, sweden; r . kumar juneja, department of animal breeding and genetics, the swedish university of agricultural sciences, s-75 007 uppsala, sweden; mitchell k . taylor, faculty of forestry, university of british columbia, vancouver, british columbia, canada. may 1983 (reuired june 1983). introduction although polar bears (ursus maritimus) were effectively protected through the international agreement on the protection of polar bears in 1973, there is still a substantial harvest in alaska, canada and greenland. there is thus increasing concern that overhunting may take place in some countries, or that industrial activities may harm polar bears in some areas. proper management and conservation require that the borders of dis crete populations are identified and defined, and that the exchange of bears between areas is quan tified. information about the extent of effective dispersal, i.e. geneflow between possible polar bear populations, is quite scarce. pedersen (1945) claimed that polar bears belonged to one uniform population that migrated clockwise around the polar basin. polar bear marwrecapture programs and satellite telemetry studies have shown that polar bears belong to several, relatively discrete, populations (larsen 1971; lentfer 1974; stirling et al. 1977, 1978, 1980; stirling & kiliaan 1980; uspensky & beli kov 1981; vibe 1982). many nations share polar bear populations, and there is often a migration and an exchange of bears across jurisdictions (parovshchikov 1967; kolz et al. 1978; larsen et al. 1980; vibe 1982). manning (1971) and wilson (1976) found geographical variation in polar bear skulls from various areas, but it is not known whether such variation is genotypic. genetic variants of different body proteins may be usable as a powerful tool for assessing affinities between different populations of a species. stud ies of many species of large mammals, however, have often shown a low level of protein variability, thereby decreasing the possible use of these meth ods. an extremely high interpopulation genetic similarity was observed in black bears (ursus 97 98 t. larsen et al. table 1. summary of materials and methods used for the study of polar bear proteins. year of sample method proteins locality collecting size used studied alaska canadian arctic svalbard east greenland alaska east greenland svalbard hudson bay, canada barents sea alaska 1967-1973 1967-1 973 19671973 1973 1974 1974 1974 1980 1980 1981 201 * 48 89 21 10 10 11 24 23 23 vpage vpage vapge sge sge sge sge ief, sge, hpage, 2-de ief. sge, hpage, 2-de ief, sge, hpage, 2-de transferrin and hemoglobin transferrin and hemoglobin transferrin and hemoglobin transferrin and hemoglobin 14 enzymes and 3 serum proteins 14 enzymes and 3 serum proteins 14 enzymes and 3 serum proteins general proteins general proteins general proteins killed bears americanus) (manlove et al. 1980) and in polar bears from east greenland (allendorf et al. 1979). the objective of our work was to study and compare possible variation in polar bear blood proteins and enzymes from several arctic areas. material and methods a total of 460 polar bear blood samples were collected and analysed between 1967 and 1981 (table 1). samples from killed bears were taken from the heart, a vein or an artery. heparin was added to blood drawn from the femoral vein of the live captured bears. samples were separated by centrifugation shortly after collection, frozen, and stored at -20°c. when a centrifuge was not available, samples were kept in a cool place for 24 hours to be separated by sedimentation before transfer to vials and freezing. vertical polyacrylamide gel electrophoresis (vpage) (raymond 1962) was performed in a tris-borate-edta buffer 0.1-m with ph 9.1 and a 6% polyacrylamide gel (cyanogum 41, fisher scientific co.). after a prerun of one hour at 250 volts, plasma or serum was pipetted out in slots in the gel. before application, a 5% solution of 1 % bromophenol blue in buffer saturated with sucrose was added to the sample. erythrocyte samples were washed three times with physio logical saline; water and 1 ml ether were added and the samples centrifuged. the supernatant was drawn off and the cells were frozen. before application to the gel, sucrose crystals were added to the samples. the electrophoresis was run at 100-150 volts for ten minutes, then at 250-300 volts for about three hours. serum or plasma proteins were stained with 9 g amido black dissolved in 400 ml water, 400 ml methanol, and 100 ml acetic acid for 20 minutes. destaining was performed for 12 hours in the same solution, omitting the amido black. all samples were collected in 1974 and were later investigated with the use of starch gel elec trophoresis (sge). twelve per cent starch gels were used in a tris-citrate lithium borate buffer of ph 8.5 or a tris-borate-edta buffer of ph 7.5. the separations were performed at 10 v/cm for three hours. proteins and enzymes were stained in accordance with the techniques rou low protein variability in polar bears 99 tinely used (shaw & prasad 1970; harris & hop kinson 1976). selected samples of serum were treated according to coppenhauer & buettner janusch (1970) with neuraminidase to determine whether the observed variation in serum proteins was induced by sialic residues (chen & sutton 1967). the serum transferrins were also partly purified by rivanol treatment according to boettcher et al. (1958). seventy samples collected in the period 1980 81 (table 1) were studied by means of isoelectric focusing (ief) in addition to sge. samples were electrofocused in a ph gradient of 4-6.5, an appropriate range for almost all polar bear serum proteins. horizontal polyacrylamide gel electro phoresis (hpage) (12% acrylamide in separa tion gel; tris-citrate-borate buffer ph 9.0) was done according to gahne et al. (1977). the serum samples were analysed by a method of two-dimensional electrophoresis (2-de) described by juneja et al. (1981). the first dimen sion separation in agarose gel (ph 8.6) was fol lowed by a second dimension separation in hori zontal polyacrylamide gel (ph 9.0). fig. 1. vertical polyacrylamide gel electrophoresis of polar bear hemoglobins. samples from (a) alaska and (s) svalbard. results vertical polyacrylamide gel electrophoresis ( v p a g e ) the initial analyses of samples collected before 1974 concentrated on studies of polymorphism in hemoglobins and transferrins by protein separa tion with vpage. the hemoglobin analysis showed an identical pattern, with one single com ponent. no polymorphism could be demon strated, and there were no visible differences between geographical areas (fig. 1). in the serum and plasma electrophoretograms, particular attention was paid to the transferrin component. no transferrin polymorphism could be demonstrated. the serum and plasma separ ations showed several different general protein patterns, which initially could be suspected to demonstrate transferrin polymorphism. auto radiography showed that only two of the bands were transferrins, a fast moving, weak compo nent, and a slower, but stronger component. comparison between the svalbard samples and the alaska samdes showed differences in the stained separations' there was only one strong and one weak transferrin fig. 2. vertical polyacrylamide gel electrophoresis of polar bear semm proteins. samples from (a) alaska and (s) svalbard. band in the svalbard samples, corresponding to transfemns are indicated by dots. 100 t . larsen et al. the pattern in the autoradiographs, there were two strong bands in the same positions in the alaskan samples (fig. 2 ) . autoradiographs of the alaskan samples could not be distinguished from the svalbard samples. however. the visual jif ferences in the electrophoretograms are most likely due to sampling differences. one possible explanation is that the second strong band in the fast moving transferrin position in the alaskan samples was caused by a haptoglobiq'hemoglobin complex. such complexes were located close to the transferrins in the electrophoretograms, as demonstrated by benzidine stains (fig. 3). the strong double band in the transferrin position could only be demonstrated in the alaskan samples of killed bears. it was probably an artifact caused by hemolysis when bears were shot. starch gel electrophoresis ( s g e ) red blood cells and serum from 31 samples col lected in 1974 were investigated in 1975. fourteen fig. 3 . vertical polyacrylamide gel electrophoresis of polar bear serum proteins. samples from (a) alaska and (s) svalbard. autoradiographs (left) show two transferrin bands. indicated by dots. benzidine stains (right) suggest haptoglobin/hemoglo bin complex bindings in the same position as the lowest trans ferrin band fig. 4 starch gel electrophoresis of polar bear serum proteins. samples from (a) alaska and (b) hudson bay. the variable bands are indicated by arrows. low protein variability in polar bears 101 12 13 14 15 0 $16 t" ------------- 18 fig. 5. interpretation of the variation found in polar bear serum proteins separated by starch gel electrophoresis. enzymes and three other proteins representing around 30 loci were resolved. the following sys tems gave good activity and resolution: non-spe cific esterase, alkaline phosphatase, acid phos phatase. catecol oxidase, catalase, malate dehydrogenase, superoxide dismutase, aldehy deoxidase, isocitrade dehydrogenase, glucose phosphate isomerase, glucose-6-phosphate dehy drogenase, 6-phosphogluconate dehydrogenase, nadp-diaphorase, hexokinase, hemoglobin, general proteins, and lipoproteins. other systems showed only weak activity (leucine aminopepti dase) or exhibited no activity (lactate dehydro genase, alphaglycerophosphate dehydrogenase, alcohol dehydrogenase, retinol dehydrogenase, betaglucuronidase, and succinate dehydrogen ase). the systems showing good resolution were investigated in the 31 bears, and of these 16 systems proved to be monomorphic. in serum, stained for general proteins, there is a system of bands showing variation i n all populations inves tigated. eighteen protein bands were resolved by sge of serum (fig. 4) where bands 11 and 12 represent transferrins. band 5 was present in some greenland bears only. bands 6 to 10 show a phenotypic variation according to fig. 5, where phenotype 1 is found in svalbard and greenland bears. phenotype 2 was found in all three popu lations and phenotype 3 was found in greenland and alaska bears. phenotypes 4 and 5 were found in svalbard bears and phenotypes 6 , 7 , and 8 were found in alaska bears. thus bands 8 and 10 could be found in alaska bears only. other bands were found in all populations. the nature and specificity of the variable serum proteins showing phenotypic variability are unknown and owing to the complexity of the variation observed, a genetic interpretation of the phenotypic variation has not been possible. bears from svalbard and greenland, however, shared the same bands in different combinations in con trast to the bears from alaska. general proteins were also investigated in the 70 bears from the period 198g1981. the same general pattern of variation as in the 1974 samples was found. there was a greater similarity between the hudson bay and the cape lisburne samples compared to the samples collected in the barents sea. graphic demonstration starch gel electropho resis variation is shown in fig. 5. isoelectric focusing (ief) analysis of serum samples yields from 43 to 63 protein bands in ph gradient 4-6.5 (fig. 6). individuals from different populations were com pared in order to estimate differences between the three populations. comparisons between sep arated proteins were performed according to fig. 6. general protein patterns of polar bear serum separated by isoelectric focusing in a ph gradient of 4-6.5 (lowest ph at top of the gel). samples from hudson bay, barents sea and alaska. 102 t . larsen et al. tegelstrom et a l . (1982). identity values between individuals from the same popdation range from 0.81 to 1 .oo. intrapopulational identities esti mated for the different populations are: hudson bay 0.95 ? 0.03 (n = 8), cape lisburne 0.95 * 0.03 (n = 8), and barents sea 0.92 * 0.06 (n = 8). there is less identity within the barents sea material and also a greater statistical variation indicating a more heterogeneous population. comparisons of individuals from different popu lations gave t h e following interpopulation ident ities: barents sea versus hudson bay 0.93 ? 0.05 (n = ll), barents sea versus cape lisburne 0.94 * 0.05 (n = 12), and cape lisburne versus hudson bay 0.96 * 0.04 (n = 13). the identity between populations is very high, and not stat istically different from the identity between ani mals from the same population. there is no stat istical identity difference between the three investigated populations. there is, though, an indication of a higher identity between bears from the north american continent compared to the animals sampled in the barents sea. with the higher resolution achieved by i e f compared to standard gel e~ectrophoresis, we could not find any protein diagnostic for the populations inves tigated, although there is variation within populations. nonspecific esterases were also investigated by i e f in a p h gradient 3-10, where 11 bands could be resolved. there was no difference between populations. horizontal polyacrylamide gel electrophoresis ( h p a g e ) polar bear serum yields from 20 to 27 protein bands (fig. 7). variation is present in the different populations, but a genetic interpretation for the observed variations is unlikely. the band which probably represents the a-foeto-protein is divided into two distinct bands in some bears in all popu lations. the most probable explanation is that the extra band is the result of age and not a genetic difference between individuals. there was vari ation in a fast moving protein where an extra band was observed in two individuals from the alaska population. this variation was also observed when the proteins were separated by two-dimensional electrophoresis (figs. 7 and 8). fig. 7. horizontal polyacrylamide electrophoresis of polar bear serum proteins. samples from alaska bands with a presumed genetic variation are indicated. these were also resolved by two-dimensional electrophoresis. fig. 8 two-dimensional electrophoresls of polar bear serum proteins. samples from alaska. the bands with a presumed genetic variation found in hpage are illustrated with arrows. two-dimemiona[ e/ectrophoresk (2-de) patterns of some samples are shown in fig. 8. low protein variability in polar bears 103 the prealbumin system with probable genetic variation, also found in hpage, is indicated. n o other variation was revealed by this technique. all together around 30 enzyme or protein loci were investigated by sge, and approximately 35 additional proteins and 10 enzymes in serum were resolved by ief, representing around 45 loci. hpage and 2-de probably revealed some additional proteins not observed by the other two methods. thus around 75 loci were analyzed all together. discussion efforts have been made in recent years to evaluate the potential of genetic information in the man agement of wildlife populations. levels of genetic variation have primarily been estimated by means of electrophoresis. the method, however, has often proved less useful owing ta the usually low level of variability found in large mammals. selander & kaufman (1973) pointed out that vertebrates generally show lower levels of elec trophoretically detectable variation than inver tebrates. they propose that large and highly mobile animals could show lower levels of vari ation than smaller and less mobile animals. the level of genetic variation in terms of protein polymorphism seems to be substantially reduced in natural populations of large compared with small mammals (mcdermid et al. 1972; bonell & selander 1974; allendorf et al. 1979; bruce & ayala 1979; ryman et al. 1980; simonsen 1982; simonsen et a l . 1982a and b). several explanations have been proposed (levins 1968; selander & kaufman 1973; ohta 1974; valentine 1976). the low variation found in the present study of 460 polar bears is in agreement with two pre vious reports on protein and enzyme variation in bears (manlove et al. 1980; allendorf et al. 1979). manlove et al. (1980) investigated 19 proteins in 233 black bears from six localities covering the species range. they found six polymorphic pro teins exhibiting two alleles. the low levels of genetic variability in these populations are towards the lower end of the range for mammals. allendorf et a l . (1979) investigated 12 enzymes by starch gel electrophoresis of sera and red blood cells in 52 polar bears from eastern greenland and found no variation. the degree of polar bear variation in blood proteins and enzymes was found to be low in this study in spite of the use of high resolution tech niques. even proteins usually found to be variable in most species (such as transferrins, gc-vitamin d binding serum protein and non-specific ester ases) are monomorphic in this species. of the 75 loci investigated, sge revealed an unidentified variable protein, and hpage another system. the sge variation indicates a closer genetic relationship between bears from alaska and can ada, compared to greenland and svalbard. this protein system could not be found in the ief, hpage, or 2-de, and has not been further investigated. it may be a tool for further identi fication of polar bear populations. extensive maryrecapture programs on polar bears have been made in all arctic countries since 1966. none of the bears marked in north america have been killed or recaptured in the eurasian arctic, or vice versa. nor have any of the radio-instrumented bears migrated between europe and north america. the common con clusion of these studies, observations of abun dance and distribution, and studies of cranial variation (manning 1971; wilson 1976), is that polar bears stay in distinctively different areas for many years. research suggests the following: svalbard, frans josef land, northern novaja zemlja and adjacent ice covered seas include the range of one population, which has connections across the greenland sea and northeast green land (larsen et al. 1980; larsen 1981; parovsh chikov 1967). the central east greenland fjords may have their own small population (vibe 1981, 1982). in the canadian arctic, there may be ten or more populations (schweinsburg et al. 1982; stirling et al. 1977, 1978, 1980; stirling & kiliaan 1980; taylor 1982). bears in the northeast cana dian arctic have connection with bears in north west greenland (schweinsburg et al. 1982; stirling et al. 1978). in alaska there may be two different populations (lentfer 1972, 1974), of which one, in the chucki sea, may have connections with bears in the soviet wrangel island and the adja cent sibirian coast (kolz et al. 1978; taylor 1982). bears in the central soviet arctic probably belong to a separate population (uspensky & belikov 1981). but the discreteness of these populations has been questioned (prevett & kolenosky 1982; stirling et a l . 1978; taylor 1982). observations from many sources show that bears are often encountered in the central polar basin, outside their normal range (lentfer 1970). such bears may come from, or migrate to, any arctic region. 104 t. larsen et al. over long periods of time, there may, there fore, be an exchange of bears and hence genetic material sufficient t o justify the early statement by pedersen (1945) that bears belong to one com mon population, at least in a genetic sense. the possibility of recent ‘bottlenecks’ caused by drastic reduction in the number of animals and therefore resulting in lowered levels of genetic variation cannot be rejected, but seems improb able. there is no evidence of any radical reduction in the number of polar bears in any arctic region in historical time. it should also be remembered that the polar bear is a relatively young species in the evolu tionary sense, and is probably not more than 250,000 years old (kurten 1976). low blood pro tein and enzyme diversity and lack of differences between populations may be explained by high selective pressure in a species which lives in a difficult environment and a highly specialized niche. our conclusion is that the lack of polymorphism in polar bear blood proteins and enzymes reflects the generally low level of protein variability that has been observed in other large mammals. even if there is little exchange of individuals between polar bear populations, such exchanges may be sufficient to create genetic uniformity over time. this fact, combined with the possible high selec tive pressure described above. may explain the lack of polymorphism observed in this study. acknowledgements. this study was sponsored by the vor wegian polar research institute and by grants from the nilsson-ehlc and erik philip-sorensen foundations. blood samples were kindly provided by e . born, c . jonkel. j w. lentfer, and c. v i b e we are grateful for help and support from polar bear projects under the alaska department of fish and game. us fish and wildlife service. and the canadian wildlife service. we received help from the sysselmann (gov ernor) in svalbard. from the crew and assistants o n the nor wegian polar research institute svalbdrd expeditions, and from the organizers of the swedish ‘ymer 80’ expedition. thanks arc expressed to those who aided our research and who par ticipated in the practical work in the laboratories: britt-marie bergquist, d r . u. s seal. and per-ivan wyoni. we thank dr. david clapman for revising the english text and professor karl fredga. dr. johan b. steen, and dr. nils chr. stenseth for valuable comments on the manuscript. references allendorf, f. w , christiansen, f. b.. dobson. t.. eanes. w. f. & frydenberg, 0. 1979: electrophoretic variation in large mammals. i the polar bear. thalarctos maritimus. hereditas 91 i 19-22. boettcher, e . w.. kistler. p. &? nitschmann, h . 19%: method of isolating the &metal binding globulin from human blood plasma. nature 181, 4 w 9 1 . bonell, m. l . & selander, r. k . 1974: elephant seals. genetic variation and near extinction. science 814, 908-909. bruce, e. j . & ayala, f. j . 1979: phylogenetic relationships between man and the apes. electrophoretic evidence. evo lution 33, 104cl1056. chen, s.-h. & sutton, h . e. 1967: bovine transferrins: sidic acid and the complex phenotype. genetics 56,425-430. coppenhauer, d . & buettner-janusch, j . 1970: transferrin in cercopithecinae. folia. primat. 13, 2 s 3 4 . gahne, b . , juneja, r . k. & grolmus, j. 1977: horizontal polycrylamide gradient gel electrophoresis for the simulta neous phenotyping of transferrin. post-transfertin, albumin and post-albumin in the blood plasma of cattle. anim. blood grps biochem. genet. 8 . 127-137. harris, h. & hopkinson, d. a . 1976: handbook of enzyme elecnophoresh in human genetics. north-holland publish ing company. juneja, r . k . , lundin, l . g. & gahne, b . 1981: genetic polymorphism of an a-protease inhibitor in mink plasma. hereditas 94, 249-252. kolz. a. l., lentfer, j. w. & fallek, h . g . 1978: polar bear tracking via satellite. int. isa biomed. sci. imtrumenration s y m p . 15. 137-144. kurtkn. b. 1976: the caoe bear story. columbia university press. new york. 163 pp. larsen, t. 1971: capturing. handling and marking polar bears in svalbard. 1. wildl. manage. 35 (i), 27-36. larsen. t. 1981: distribution, numbers, and population charac teristics of polar bears in svalbard. report to the 8th meeting o f t h e iucn polar bear specialist group. mimeo. 14 pp. larsen, t . , jonkel. c. & vibe, c . 1980: satellite radiotracking of polar bears between svalbard and greenland. in meslow, c. (ed.). bears their biology and management. bear biology assor. conf. ser. 4 . in press. lentfer. j . w. 1970: polar bear research and management in alaska 1 9 6 b 6 9 . iucn publications new series suppl. paper 29, 45-66. lentfer. j . w . 1972: alaska polar bear research and manage ment 197c-71. iucn publication new series suppl. paper 35, 29-39. lentfer. j . w . 1974: discreteness of alaskan polar bear popu lations. international game biol. 1 1 , 323-329. levins. r . 1968: evolution in changing environments: some theorertcal explorarions. princeton university press, princeton. n.j. 120 pp. manlove. m. n . . baccus. r.. pelton. m . r . , smith, m. h. & graber. d. 1980: biochemical variation in the black bear. pp. 3 7 4 1 in martinka. c. & mcarthur, k. l. (eds.), bears their biology and management. bear biol. assoc. conf. ser. 3. 375 pp. manning. t . h . 1971: geographical variation in the polar bear. canadian wildlife service report series n o . 13. 27 pp. mcdermid. e. m.. ananthakrishan, r. & agar, n . s. 1972: electrophoretic investigation of plasma and red cell proteins and enzymes of macquarie island elephant seals. anim. blood groups biochem. genet. 3 , 85-94, ohta, t. 1974: mutational pressure as the main cause of mol ecular evolution and polymorphism. nature 252, 351-354. parovshchikov, v. y . 1967: the polar bear in frans josef land. problems of rhe north 1 1 , 149-159. pedersen, a . 1945: der eisbar. verbreitung und lebemweise. e . bruun & co., kebenhavn. 166 pp. . low protein variability in polar bears 105 prevett, j. p. & kolenosky, g. b. 1982: the status of polar bears in ontario. le naturaliste canadian 109(4), 933-939. raymond, s. 1962: convenient apparatus for gel electropho resis. clin. chem. 8 , 44-470. ryman, n . , reuterwall, c., nygren, k. & nygren, t. 1980: genetic variation and differentiation in scandinavian moose (alces alces): are large mammals monomorphic? evolution 34, 1037-1049. schweinsburg, r . e., lee, j. l. & latour, p. b. 1982: distri bution, movement, and abundance of polar bears in lancaster sound, northwest territories. arctic 35, 159-169. selander, r. k. & kaufman, d. w. 1973: genetic variability and strategies of adaptation in animals. proc. natl. acad. sci. 70, 1875-1877. shaw, c. & prasad, r . 1970: starch gel electrophoresis of enzymes a compilation of recipes. biochem. genet. 4 , simonsen, v. 1982: electrophoretic variation in large mammals. 11. the red fox, vulpes uulpes, the stoat, mustela erminea, the weasel, mustela niualis, the polar cat, mustela putorius, the pine marten, martes martes, the beech marten, martes fiona, and the badger, meles meles. hereditas 96, 299-305. simonsen, v., allendod, f. w., eanes, w. f. & kapel, f. 0. 1982a: electrophoretic variation in large mammals. 111. the ringed seal, pusa hispida, the harp seal, papophilus groen landicur, and the hooded seal. cystophora cristata. hereditas 97, 87-90. simonsen, v., born, e. w. & kristensen, t. 1982b: electro phoretic variation in large mammals. iv. the atlantic walrus, odobenus rosmarus rosmarus (l). hereditas 97, 91-94. stirling, i . , jonkel, c., smith, p., robertson, r. & cross, d. 1977: the ecology of the polar bear along the western coast of hudson bay. canadian wildl. serv. occas. paper 33, 64 pp. 297-320. stirling, i., schweinsburg, r. e., calvert, w. & kiliaan, h. p. l. 1978: population ecology of the polar bear along the proposed arctic islands gas pipeline route. final report to the environmental management seruice, department of the environment, edmonton, canada, 93 pp. stirling, i . , calvert, w. & andriashek, d. 1980: population ecology studies of the polar bear in the area of south-eastern baffin island. canadian wildl. serv. occas. paper 44, 33 pp. stirling, i. & kiliaan, h. p. l. 1980: population ecology studies of the polar bear in northern labrador. canadian wildl. s e w . occas. paper 42, 21 pp. taylor, m. k. 1982: the distribution and abundance of polar bears in the beaufort and chucki seas. ph.d. thesis, 2 vols. tegelstrom, h . , wyoni, p . 4 . & ryttman, h. 1982: thin layer isoelectric focusing as a taxonomic tool. ann. zool. fenici. 19, 20?-207. uspensky, s . m. & belikov, s. e. 1981: polar bear research and management in the ussr 1979-80. iucn publ. new ser. suppl. paper. in print. valentine, j. w. 1976: genetic strategies of adaptation. pp. 78-94 in ayala, f. j . (ed.), molecular evolution, sinauer ass. vibe, c. 1981: miscellaneous information relating to polar bears in greenland. proceedings of the 8th working meeting of the iucn/ssc polar bear specialist group. in print. vibe, c. 1982: grenlands hvide bjerne. naturens uerden 1982, wilson, d. e. 1976: cranial variation in polar bears. pp. 447-453 in pelton, m . r., lentfer, j . w. & folk, e . g . (eds.). bears their biology and management. iucn publ. new ser. 40, 467 pp. 353 pp. 41-56. observations of bowhead whales in west greenland during summer research note observations of bowhead whales in west greenland during summer david boertmann,1 katrine raundrup,2 josephine nymand,2 janne fritt-rasmussen1 & kasper l. johansen1 1department of ecoscience, aarhus university, roskilde, denmark 2greenland institute of natural resources, nuuk, greenland abstract bowhead whales (baleana mysticetus) are usually away from west greenland waters during summer. reported here is an observation of at least six bowhead whales in july 2022 in the uummannaq fjord system of west greenland. keywords balaena mysticetus; eastern canada–west greenland stock; summer aggregation; migration; uummannaq fjord abbreviations sst: sea-surface temperature ibcao: the international bathymetric chart of the arctic ocean   citation: polar research 2023, 42, 9436, http://dx.doi.org/10.33265/polar.v42.9436 copyright: © 2023 d. boertmann et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 20 july 2023 competing interests and funding: the authors report no conflict of interest. these observations were made during a regional environmental baseline assessment initiated and funded by the environmental agency for mineral resource activities (greenland government). correspondence: david boertmann, department of ecoscience, aarhus university, frederiksborgvej 399, dk-4000 roskilde, denmark. e-mail: dmb@ecos.au.dk   introduction bowhead whales (baleana mysticetus) of the eastern canada–west greenland stock occur off west greenland during january to june, most numerously from april (tervo et al. 2009; heide-jørgensen et al. 2021). tracked from the feeding grounds in disko bay in april and may 2009 and 2010, 78 tagged whales all left greenland waters and migrated north-west towards the canadian arctic archipelago during may and june (heide-jørgensen & laidre 2021; heide-jørgensen et al. 2021). in july and august they were mainly distributed around baffin island and in the waters of the canadian arctic archipelago (nielsen et al. 2015; heide-jørgensen & laidre 2021). observations during land-based fieldwork in summer 2022, a number of bowhead whales were observed in a bay in south-west svartenhuk peninsula (siggup nunaa), in the northern part of uummannaq fjord, west greenland (71.40°n, 55.03°w; fig. 1). on 24 july 2022, a relatively small and greyish, mottled bowhead whale was observed during a boat transfer from eastern svartenhuk peninsula to the bay of tasiussap imaa, a shallow bay in which there were several icebergs, ranging from bergy bits to large bergs. we got the impression that it was a stray young whale, but the following days revealed that several bowhead whales were in the bay. on 26 july, a single large whale was seen basking at the surface 150 m from the coast, and the same evening up to four large whales were simultaneously moving slowly back and forth off our campsite, most likely feeding (fig. 1). the following day, four whales were again observed at approximatively the same positions, and later, during a boat transfer a single whale was seen somewhat to the west of the four whales. finally, the same evening, our boat captain observed two whales on his trip back to uummannaq. fig. 1 positions of at least six different bowhead whales, observed 24–27 july 2022. the numbers by the asterisks indicate the observation date in july. bathymetry is shown with depth curves with an equidistance of 25 m, interpolated based on the ibcao, version 4 (jakobsson et al. 2020). the depth model is probably not accurate in the specific area, as icebergs with a keel much deeper than 25 m were present in the bay. daytime ssts on 26 july 2023 (shown in shades of blue) in the bay and the waters south of are derived from aqua-modis (nasa ocean biology processing group 2023a). as the first observed whale was clearly different from the (at least) five observed the following days, altogether there was a minimum of six whales staying in the bay of tasiussap imaa in july 2022; it is possible that there were more. if only a single whale had been observed, it could easily have been characterized as a stray animal, but since several individuals were observed, some of which were apparently feeding, this is not likely. another observation is worth mentioning in this context. on 3 june 2022, a bowhead whale was caught and landed at qaarsut, in uummannaq fjord, 110 km south-east of the site where we observed the whales (m.p. heide-jørgensen, pers. comm.). this was also outside the normal season for bowhead whales in west greenland and at a location where bowhead whales usually do not occur. people in uummannaq told us that bowhead whales had been observed during summer in the region in recent years. discussion eschricht & reinhard (1866) reported in detail the arrivals and departures of bowhead whales from whaling stations (sisimiut and qeqertarsuaq) in west greenland between 67° and 70°n and more scattered observations further south to maniitsoq at 65°n and north to upernavik at 73°n during the years 1780 to 1839. at sisimiut the arrival dates ranged between 28 november and 22 january, with an outlier on 10 february, and at qeqertarsuaq between 12 november and 6 january. the days of last annual observations at sisimiut ranged from 12 february to 9 april and at qeqertarsuaq from 26 april to 25 june. these dates correspond to the occurrence pattern seen today, and only one observation from july was reported by eschricht & reinhard (1866): a young whale was captured on 11 july 1803 near saitok island (probably saatut), in uummannaq fjord, resembling the 2022 observations reported here. this is the only historical observation in the uummannaq fjord system known to us. examining movements of bowhead whales in relation to sst, chambault et al. (2018) found that the whales target areas with ssts between −0.5 and 2 °c. on 26 july 2022, the sst in the area where we observed the whales ranged from 2.9 to 3.2 °c, with the lowest values in the bay itself (fig. 1). the average sst for the period 20 to 27 july ranged from 4.6 to 6.3 °c (nasa ocean biology processing group 2023a, 2023b). this is considerably higher than the preferred temperatures reported by chambault et al. (2018). based on this information, the tasiussap imaa bay seems not to be an optimal habitat for bowhead whales. whether our observations, along with those of local residents, are early signs of a new summer ground for bowhead whales in west greenland or they represent a short-lived occurrence in a species that shows flexibility in movement patterns and habitat selection (see chambault et al. 2018) is hard to assess. but with the increasing warming in the arctic (rantanen et al. 2022), it is likely that the bay’s importance as a summer habitat for the whales will be of short term, because the ssts in the future will deviate even more from the temperatures preferred by the whales. acknowledgements the authors thank paaluk kreutzmann, uummannaq seasafari aps, for skilful navigation and for sharing his knowledge of bowhead whales, and the two anonymous reviewers who improved the manuscript. references chambault p., albertsen c.m., patterson t.a., hansen r.g., tervo o, laidre k.l. & heide-jørgensen m.p. 2018. sea surface temperatures predicts the movements of an arctic cetacean: the bowhead whale. scientific reports 8, article no. 9658, doi: 10.1038/s41598-018-27966-1. eschricht d.f. & reinhardt j. 1866. on the greenland right-whale (balaena mysticetus, linn.), with especial reference to its geographical distribution and migrations in times past and present, and to its external and internal characteristics. in h.f. flower (ed.): recent memoirs on the cetacea. pp. 1–150. london: ray society. heide-jørgensen m.p., hansen r.g. & shpak o.v. 2021. distribution, migrations, and ecology of the atlantic and the okhotsk sea populations. in j.c. george & j.g.m. therwissen (eds.): the bowhead whale balaena mysticetus: biology and human interactions. pp. 57–75. london: academic press. heide-jørgensen m.p. & laidre k.l. 2021. box 7. movements and space use-patterns of bowhead whales in baffin bay, 2009 and 2010. in d. boertmann & a. mosbech (eds.): disko west—an updated strategic environmental impact assessment of oil and gas activities. scientific report from dce—danish centre for environment and energy 438. pp. 150–152. aarhus, denmark: aarhus university. jakobsson m., mayer l.a., bringensparr c. castro c.f., mohammad r., johnson p., ketter t., accettella d., amblas d., an l., arndt j.e., canals m., casamor j.l., chauché n., coakley b., danielson s., demarte m., dickson m.-l., dorschel b., dowdeswell j.a., dreutter s., fremand a.c., gallant d., hall j.k., hehemann l., hodnesdal h., hong j., ivaldi r., kane e., klaucke i., krawczyk d.w., kristoffersen y., kuipers b.r., millan r., masetti g., morlighem m., noormets r., prescott m.m., rebesco m., rignot e., semiletov i., tate a.j., travaglini p., velicogna i., weatherall p., weinrebe w., willis j.k, wood m., zarayskaya y., zhang t., zimmermann m. & zinglersen k.b. 2020. the international bathymetric chart of the arctic ocean version 4.0. scientific data 7, article no.176, doi: 10.1038/s41597-020-0520-9. nasa ocean biology processing group 2023a. aqua-modis sea surface temperature (11 u daytime), daily (20220726), 4km, standard mapped image, level 3. accessed on the internet at https://oceandata.sci.gsfc.nasa.gov/cgi/getfile/aqua_modis.20220726.l3m.day.sst.sst.4km.nc on 6 january 2023. nasa ocean biology processing group 2023b. aqua-modis sea surface temperature (11 u daytime), 8-day (20220720-20220727), 4km, standard mapped image, level 3. accessed on the internet at https://oceandata.sci.gsfc.nasa.gov/cgi/getfile/aqua_modis.20220720_20220727.l3m.8d.sst.sst.4km.nc on 9 january 2023. nielsen n.h., laidre k., larsen r.s. & heide-jørgensen m.p. 2015. identification of potential foraging areas for bowhead whales in baffin bay and adjacent waters. arctic 68, 169–179, doi: 10.14430/arctic4488. rantanen m., karpechko a.y., lipponen a., nordling k., hyvärinen o., ruosteenoja k., vihma t. & laaksonen a. 2022. the arctic has warmed nearly four times faster than the globe since 1979. communications earth & environment 3, article no. 168, doi: 10.1038/s43247-022-00498-3. tervo o.m., parks s.e. & miller l.a. 2009. seasonal changes in the vocal behavior of bowhead whales (balaena mysticetus) in disko bay, western-greenland. journal of the acoustical society of america 126, 1570–1580, doi: 10.1121/1.3158941. no job name status of the black-legged kittiwake (rissa tridactyla) breeding population in greenland, 2008por_169 391..403 aili lage labansen,1 flemming merkel,2 david boertmann2 & jens nyeland3 1 greenland institute of natural resources, po box 570, dk-3900 nuuk, greenland 2 national environmental research institute, department of arctic environment, aarhus university, frederiksborgvej 399, dk-4000 roskilde, denmark 3 naturama, dronningmaen 30, dk-5700 svendborg, denmark abstract based on the intensified survey efforts (since 2003) of greenlandic breeding colonies of black-legged kittiwake (rissa tridactyla), the total greenland breeding population was estimated at roughly 110 000 breeding pairs, constituting about 4% of the total north atlantic breeding population. this population estimate of black-legged kittiwake is the most reliable and updated estimate hitherto reported for greenland. the results confirm considerable population declines in many areas of west greenland. the breeding population of blacklegged kittiwakes in the qaanaaq area appears healthy, whereas the rest of the west coast has experienced declines, especially the north-western region (in the area from upernavik to kangaatsiaq). exactly when these reductions have occurred is uncertain because of the limited survey effort in the past, but some colonies declined as far back as the mid-1900s, whereas declines of other colonies have occurred since the 1970–80s. east greenland data from the past are few, but recent aerial surveys confirm that the abundance of breeding kittiwakes on this inaccessible coast is low. the reasons for the west greenland declines are not documented. poor feeding conditions and a high hunting pressure, particularly prior to 2002 when the open season was shortened considerably, are possible explanations. keywords black-legged kittiwake; greenland; population status; rissa tridactyla. correspondence aili lage labansen, greenland institute of natural resources, po box 570, dk-3900 nuuk, greenland. e-mail: aili@natur.gl doi:10.1111/j.1751-8369.2010.00169.x the black-legged kittiwake rissa tridactyla (hereafter kittiwake) is a widely distributed seabird in the circumpolar arctic (cramp & simmons 1983; hatch et al. 1993), numbering more than 5 million pairs when all national population estimates are summed (cramp & simmons 1983; hatch et al. 1993; anker-nilssen et al. 2000; mitchell et al. 2004; bakken et al. 2006; hatch et al. 2008; barrett et al. 2006). reports on declines in breeding populations, poor breeding performance and so on, from many regions of the breeding range of kittiwakes, have led to an increased international focus on this species (regehr & montevecchi 1997; carscadden et al. 2002; frederiksen et al. 2004; mitchell et al. 2004; barrett et al. 2006; bornaechea & gardarsson 2006; gardarsson 2006; mavor et al. 2006; sunnanå & fossheim 2008). hence, the kittiwake is now considered to be a species of conservation concern by the arctic council working group conservation of arctic flora and fauna (caff), and the need for a circumpolar conservation strategy and action plan is being considered by caff’s seabird expert group. the kittiwake is categorized as vulnerable (vu) on the greenland red list (boertmann 2007). the kittiwake is a widespread breeder in greenland, particularly along the west coast. former estimates of the west greenland breeding population have been somewhere between 80 000 and 200 000 pairs (boertmann et al. 1996; bakken et al. 2006), based largely on outdated surveys (as old as 80 years) of varying quality, and the east greenland population has been virtually unknown. as the kittiwake is subject to hunting in greenland, in contrast to elsewhere in the north atlantic (merkel & barry 2008), an updated and more reliable estimate of the breeding population is required for management purposes. this was underlined by nyeland (2004), who documented a general decreasing trend in the breeding population in west greenland during the past century. therefore, the survey effort of the greenland kittiwake breeding population was intensified after 2003 with the aim of surveying all significant breeding areas within a polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 391 mailto:aili@natur.gl reasonably short time frame. the results from these surveys have been published in regional reports (boertmann 2004, 2006; nyeland & mathæussen 2004; burnham et al. 2005; merkel et al. 2007; nyeland 2007), and in combination with unpublished results from other surveys, allow us to make an updated estimate of the breeding population in greenland. the objective of this study is to present an updated population estimate of breeding kittiwakes in greenland. key breeding areas are identified and apparent population trends are discussed. methods data on kittiwake breeding numbers are stored in a database containing information about greenland’s seabird colonies, which is maintained by the national environmental research institute and is available on the institute’s website (boertmann et al. 1996; bakken et al. 2006). this database includes historical kittiwake data (breeding location data back to 1898) as well as all survey results from recent years (e.g., boertmann et al. 1996; boertmann 2006; merkel et al. 2007). the database contains information on colony location and survey results for all colonial seabird species breeding in greenland (boertmann et al. 1996; bakken et al. 2006). from this database the most recent survey results (2007 was the most recent survey year in west greenland; 2008 in east greenland) from all known kittiwake colonies in greenland were extracted. these data are expressed either as the number of individuals or nests/ pairs. nest/pairs are here presented as “apparently occupied nests” (aons), and numbers of individuals were converted to number of aons by using a k-factor of 0.65. this was derived from a study in qaanaaq (merkel et al. 2007), which, as a result of the lack of data from other regions, was applied to the entire area. survey data in the database are categorized as being of high, medium or low quality. colonies are spatially grouped according to administrative municipalities, which are named after the largest town. for the purpose of this presentation the west greenland data were further grouped into four larger regions (north, north-west, south-west and south), and the east greenland data were grouped into two regions (north-east and south-east), as shown in fig. 1. all survey results in the west greenland data set were obtained by direct counts on site (primarily from a boat using binoculars), except for two colonies in ilulissat, two in upernavik and the four colonies in the qaanaaq area, which were all photographed systematically, and aons were counted from these photographs (boertmann 2006; merkel et al. 2007; nyeland 2007). colony surveys were mainly carried out in july (96% of the west greenland surveys), which is the time when at least one of the adults or large chicks are present on their nests. a few colonies were surveyed in late june (n = 7), in august (n = 3) and in very early september (n = 1) (see the appendix). east greenland data were treated separately. in june– july 2008, an aerial seabird survey was conducted along the entire coast from kap farvel (60°n) to kap morris jesup (83.5°n), and this contributed significantly to the otherwise limited data for this part of greenland (boertmann et al. 2009; merkel et al. 2010). results west greenland sixteen west greenland kittiwake colonies in the database may never have existed, and were excluded from the data set. the remaining 246 colonies, accepted to have been occupied at some time in west greenland since 1920, were included in the present summary (see the appendix; fig. 1). the median year of the most recent count of these colonies was 2003 (standard deviation = 6.7 years); of the 246 colonies, 64.6% had been visited since 2003 and 92.3% within the past 10 years (1998–2007) (table 1). the remaining 19 colonies (with most recent survey data of more than 10 years old) were all small (�65 aons) or empty. the oldest count included in the present summary is from 1954 (see the appendix; table 1). among the 246 colonies, 139 were occupied by breeding pairs during the most recent visit, and their numbers add up to a total west greenland breeding population of 103 348 aons (fig. 1; table 2). as much as 95.8% of the total number of aons were counted in 2003 or later, and 99.7% in 1998 or later (table 1). the mean colony size was 744 aons, with a range from 1 to 18 707. the median colony size was 57 aons, and only three colonies had more than 10 000 aons (fig. 1). data from 12 colonies were converted from number of individuals to aons, and added up to 3588 aons (3.5% of the total number of aons). the quality of the count data were categorized as high, medium and low for 94, 20 and nine colonies, respectively. for 16 colonies the quality of the count data was not reported (see the appendix). low-quality count data accounted for 0.3% of the total number of aons. count data of medium and high quality accounted for 98.4% of the total number of aons. figure 1 and table 2 give an overview of the regional distribution and abundance in west greenland. the northern region is characterized by very few but large colonies, holding 34.5% of the west greenland breeding population in only four colonies. colonies are far more abundant in the north-west region, from upernavik in the north to kangaatsiaq in the south, being home to 71.1% of all registered colonies, although they house kittiwake population status in greenland a.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd392 x xx x x x xx x xxxxxxxx xxxx xxx x xx x xx xx x xx x xxxx xxx x x x xx xx x xx xx x xx x xxx xxxxx x xxx x xxxxxxxx x x xxx xx x xxx x x x xx x xxx x x x north north-west south-west south north-east south-east north-east water polynya scoresby sound wollaston forland polynya nuuk narsaq qaanaaq aasiaat paamiut tasiilaq sisimiut ivittuut qaqortoq upernavik uummannaq ilulissat maniitsoq nanortalik kangaatsiaq qeqertarsuaq qasigiannguit ittoqqortoormiit 15°e10°e5°e0°5°w10°w15°w 25°w 25°w 30°w35°w 35°w 40°w45°w 45°w 50°w55°w 55°w65°w70°w75°w80°w85°w90°w95°w 75°n 75°n 70°n 70°n 65°n 65°n 60°n 60°n 0 200 400 km kittiwake colonies no . of pairs 1 -100 101 -1000 1001 10000 10001 -20000 x 0 x fig. 1 map of greenland with locations of the largest town from each municipality (marked as squares), and locations of all 246 registered breeding colonies in west greenland and 16 registered breeding colonies in east greenland. the size of the colonies at the most recent visit (with 2007 being the most recent survey year in west greenland and 2008 in east greenland) is indicated by the size of the circle. empty colonies are marked with an x. the borders between the four regions in west greenland (north, north-west, south-west and south) and the two regions in east greenland (north-east and south-east) are indicated with dotted lines. kittiwake population status in greenlanda.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 393 only 29.5% of the breeding population. the south-west region (from sisimiut to nuuk) holds 19.1% of all the colonies, and 32.3% of the total breeding population. the smallest numbers of kittiwakes were found in the southern region (from paamiut to nanortalik), with 8.1% of the colonies and 3.7% of the breeding population (table 2). of the 246 west greenland colonies included in the data set, 107 (43%) were abandoned at the latest survey. only in qaanaaq were no colonies abandoned, whereas 51% were abandoned in the north-west, 26% in the south-west and 25% in the southern greenland region (table 2). looking at the smaller regions, the municipalities, the largest numbers of breeding kittiwakes occur in qaanaaq, maniitsoq and ilulissat, with 34.5, 31.4 and 21.3%, respectively, of the total west greenland population. the remaining municipalities hold between 0 and 6% of the breeding population (fig. 1; table 2). the municipalities with the largest numbers of empty kittiwake colonies during the most recent survey were uummannaq (27 of 39), kangaatsiaq (25 of 35) and ilulissat (17 of 40) (table 2). east greenland only 16 breeding colonies or possible breeding colonies are recorded from east greenland (see the appendix; fig. 1). four are in the region between 60° and 69°n (in the south-east region), and 12 are found north of 69°n (in the north-east region). nine colonies were surveyed in 2008, of which three were new and one abandoned. one new colony was recorded in north-east and two new colonies were recorded in south-east greenland, although the name of one of the latter colonies indicates that the site has previously been occupied by kittiwakes table 1 distribution of the number (n) of kittiwake colonies and number of apparently occupied nests (aons) by the most recent survey year in west greenland. year ncolonies naons ncolonies (%) naons (%) cumulative ncolonies (%) naons (%) 2007 28 4884 11.4 4.7 11.4 4.7 2006 10 35 746 4.1 34.6 15.4 39.3 2005 74 23 301 30.1 22.5 45.5 61.9 2004 1 0 0.4 0.0 45.9 61.9 2003 46 35 025 18.7 33.9 64.6 95.8 2002 2 2623 0.8 2.5 65.4 98.3 2001 3 10 1.2 0.0 66.7 98.3 2000 40 732 16.3 0.7 82.9 99.0 1999 6 301 2.4 0.3 85.4 99.3 1998 17 514 6.9 0.5 92.3 99.8 1988–97 8 121 3.3 0.1 95.5 99.9 1978–87 2 50 0.8 0.0 96.3 100.0 1968–77 8 0 3.3 0.0 99.6 100.0 1958–67 1948–57 1 41 0.4 0.0 100.0 100.0 total 246 103 348 table 2 number of kittiwake colonies, number of colonies occupied by breeders and number of apparently occupied nests (aons) at the most recent survey (with 2007 being the most recent survey year in west greenland and 2008 in east greenland) within each region in greenland. the regions in west greenland are divided further into municipalities. region municipality number of colonies number of aonstotal occupied north qaanaaq 4 4 35 666 north-west upernavik 42 32 6230 uummannaq 39 12 732 qeqertarsuaq 6 2 75 ilulissat 40 17 22 034 qasigiannguit 12 5 323 aasiaat 1 0 0 kangaatsiaq 35 17 1065 subtotal north-west 175 85 28 376 south-west sisimiut 5 1 50 maniitsoq 35 29 32 421 nuuk 7 5 905 subtotal south-west 47 35 33 376 south paamiut 8 4 3295 qaqortoq 3 3 188 narsaq 5 4 299 nanortalik 4 4 65 subtotal south 20 15 3847 west greenland total 246 139 103 348 north-east 12 12 3537 south-east 4 3 ca. 200 total 262 155 107 085 kittiwake population status in greenland a.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd394 (see the appendix). five colonies north of 69°n were surveyed in 2003–04 by gilg (2005) (in two of these kittiwakes were present, but breeding was not confirmed), and the remaining two colonies have not been surveyed since 1993 and 1933, respectively. the colonies in east greenland are relatively small (maximum 1300 aons), and the sum of the latest counts adds up to less than 4000 aons (table 2). discussion numbers the results of recent kittiwake surveys have improved our knowledge on the status and distribution of the breeding population of kittiwakes in greenland considerably. given the large distribution range and the often remote locations of the breeding colonies, the presented population estimate of nearly 110 000 pairs must be considered as a good estimate. the total estimate is within the range of former estimates, but has now been updated and much better documented (boertmann et al. 1996; bakken et al. 2006). population estimates based on surveys distributed over time suffer from some sources of error. one is interannual variation in attendance at breeding colonies (hatch & hatch 1988; baird 1990). however, considering the large number of colonies counted within a relatively short time frame, a balance between unusually high or low colony attendances in the survey year is expected. another factor is the possibility that some of the colonies found with few or no breeding pairs more than 10 years ago may have changed status. yet, large increases in colony size are unlikely to stay unnoticed in west greenland, where local people frequently travel along the coasts and are very aware of the presence of seabird colonies. as the majority of the kittiwake data were collected as aons in july, before the fledging period (when prospecting immature birds may occupy empty nests), the population estimates are not highly sensitive to variation in daily or seasonal attendance (boulinier et al. 1996; cadiou & monnat 1996). count data of kittiwakes are most commonly given in aons (e.g., mitchell et al. 2004; barrett et al. 2006), and the k-factor used to convert from the number of individuals to aons may not be representative for all of greenland. however, as most count data were collected as aons (96.5%), this error is small. the small contribution of data categorized as being of low quality is similarly considered a minor source of error (0.4% of the total number of aons). the fact that all the largest colonies and the areas with high densities of registered colonies were covered in the more recent surveys should secure a good estimate for the population status in west greenland. the present estimate of the greenland breeding population constitutes about 3.8% of the north atlantic kittiwake population (cramp & simmons 1983; ankernilssen et al. 2000; mitchell et al. 2004; bakken et al. 2006; barrett et al. 2006; hatch et al. 2008), which is less than the 8–15% previously indicated (boertmann et al. 1996; bakken et al. 2006). this disparity must be ascribed to the higher quality of the current data, and does not document a shift in the size of the populations. distribution by far the majority of the population is distributed along the west greenland coast, with two key areas: maniitsoq and qaanaaq. the west greenland population estimate of breeding kittiwakes falls within the range of former estimates, although the regional distribution is somewhat different from previous perceptions (boertmann et al. 1996; nyeland & mathæussen 2004), in that the qaanaaq area is now identified as equally or more important than the maniitsoq area (table 2). in contrast to west greenland, the east greenland coast is much more influenced by sea ice in spring and summer (hansen et al. 2008; hvidegaard et al. 2008), and the 2008 aerial survey confirmed that this coast holds only a sparse and scattered breeding population of kittiwakes. all the important colonies are located at the major coastal polynyas: the scoresby sund polynya (five colonies, including the largest east greenland colony, with 1300 aons), the wollaston forland polynya (three small colonies, with a maximum of 75 aons) and the northeast water polynya (one colony, with 873 aons). the remaining three colonies (<50 aons) are in the northern dove bay, which becomes free of ice relatively early. new information (available after the 2008 survey) indicates that more colonies of minor sizes may be found along this remote and inaccessible coast of south-east greenland: in 2006 about five small colonies with 20–120 aons (in total ca. 340 aons) were located between tasiilaq and umiivik (a. rosing-asvid, pers. comm.). however, even if more colonies remain unknown along this remote and harsh coastline of east greenland, they are likely to be small and unstable. trends west greenland. the size of the qaanaaq population, in the north, is much larger than the former estimates of 14 000 from 1987 (kampp 1990). however, the original 1987 estimates were crude because these colonies were visited primarily for monitoring thick-billed murres (uria lomvia). moreover, nests at the two largest colonies are located high above sea level (up to ca. 400 m a.s.l.), and kittiwake population status in greenlanda.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 395 are often dispersed over large cliff areas, which may have caused an underestimation in 1987 (merkel et al. 2007). archived photos from 1987 of selected areas indicate that the kittiwakes were at least as plentiful then as today. in one colony (76014) fewer birds were counted in the 2006 photographs (2793 birds in 1987 versus 2484 birds in 2006; 17 colony sections), whereas the opposite was the case in another colony (77002; 659 birds in 1987 versus 733 birds in 2006; six colony sections). in total, the comparison of 23 colony sections indicates a small population decline of ca. 7% (greenland institute of natural resources, unpubl. data). nearby high-arctic colonies of kittiwakes in barrow strait, canada, are doing well, and the area has experienced significant increases in the breeding population since the 1970s (mallory et al. 2009). the breeding population of the north-west region, on the other hand, appears to have experienced a substantial decline, indicated by the large number of abandoned colonies (fig. 1), as well as large reductions in colony sizes (burnham et al. 2005; boertmann 2006). the updated figures show a decrease of 39, 79 and 36% in number of aons in upernavik, uummannaq and the disko bay area (from ilulissat to aasiaat), respectively, compared with previous information (boertmann et al. 1996). however, it is uncertain when these reductions have occurred because of the limited survey effort in the past (burnham et al. 2005; boertmann 2006). the uummannaq area shows the most drastic declines (from 268 000 aons in 1920 to 1100 aons in 2000), with large reductions in the number of colonies as well as birds, a decline that may have happened at any time during the past 90 years, given that many colonies had not been surveyed since 1920 (burnham et al. 2005). however, data from a few larger colonies indicate some reduction by 1949, and a survey in 1984 showed that several large colonies were abandoned by then (burnham et al. 2005). in the disko bay region, and the fjords immediately to the south of the bay, substantial decreases were recorded in 2003. for example, by 2003 the populations in the fjords arfersiorfik (n = 15 colonies and 3099 aons in 1954) and nordre strømfjord (n = 9 colonies with 715 aons in 1954) were reduced by 75 and 88%, respectively. even larger reductions may have taken place in the disko bay, but presumed exaggerated survey results in the 1950s preclude sound comparisons (boertmann 2006). the latest survey (2003) of the maniitsoq area concluded that the breeding population of this key breeding area had been halved since 1977 (nyeland & mathæussen 2004), and for some of the larger colonies, this decrease had occurred by the early 1990s (nyeland 2004). similarly, the breeding population of the surveyed colonies in south greenland has decreased by 60% since the previous (1970–80s) counts (boertmann 2004). the southwest and south greenland regions show a common characteristic. even though the total number of aons has decreased, the population is now more dispersed, as several new and small colonies have been established (boertmann 2004; nyeland & mathæussen 2004). such small colonies are often unstable over time, but this phenomenon may give a false impression of a healthy and increasing population (nyeland & mathæussen 2004). east greenland. in 2004 the population in north-east greenland seemed to have increased considerably (gilg 2005). this was, however, moderated in 2008, when six of these colonies had decreased from 700 to 302 aons (see the appendix). despite this decrease, the conditions for kittiwakes have probably improved in recent years, because less drift ice has occurred along the coasts in the summer months (johannessen et al. 2004; hansen et al. 2008; hvidegaard et al. 2008). this is underlined by the fact that the boreal lesser black-backed gull (larus fuscus) has extended its breeding range to these coasts of greenland in recent years (boertmann 2008). reasons for decline. the exploitation of seabirds in greenland (hunting and egg collecting) has been a key factor for the decrease in several breeding seabird populations, such as the thick-billed murre and common eider (somateria mollisima) (kampp et al. 1994; merkel 2004), and may also be a contributing factor for the declines in the kittiwake population. hunters in greenland are annually obliged to report the number of birds taken each month, and these bag records date back to 1993. during the first year as many as 63 000 birds were reported to have been killed, but this decreased gradually to about 32 000 in 2001 (government of greenland, unpubl. hunting statistics 2008). from 2002 the open season was shortened from 16 august–31 may to 1 september–15 february (government of greenland 2002), after which the annual harvest declined further, and has stabilized at roughly 8000 birds (government of greenland, unpubl. hunting statistics 2008). these figures must be considered as index values because an uncertain number of birds are not reported, however, the pre-2002 records indicate that more than half of the annual catches were from the spring period. ring recoveries indicate that there was a higher fraction of greenlandic breeders in the spring catches than in the autumn catches, whereas the autumn catches had a higher fraction of younger birds and of adult breeders from abroad (lyngs 2003). thus, the spring harvest may have been more harmful to the greenlandic breeding population than the autumn harvest, both in terms of direct mortality and from disturbances as a result of hunting close to breeding kittiwake population status in greenland a.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd396 colonies. however, a population effect of the reduced hunting season has yet to be observed. so far, the linkage between the population decline and the harvest has not been as clear for kittiwakes as for other seabirds harvested in greenland (nyeland 2004). kittiwakes are pelagic surface feeders, which, particularly in the breeding season, makes them more vulnerable to reduced food availability (furness & tasker 2000). in some areas of the north atlantic, the observed reductions in breeding populations as well as reduced reproductive success of kittiwakes has been connected to limited access to suitable food resources as a result of large-scale shifts in marine ecosystems (ekker 2008). in canada, a clear demarcation in population trends and biology between kittiwake colonies in the high arctic and along the atlantic coast give a similar picture as in greenland, of healthy colonies in the high arctic and colonies with reduced breeding populations further south (gaston et al. 2009). the colonies in atlantic canada have decreased because of changes in feeding regimes (regehr & montevecchi 1997; gaston et al. 2009). little is known about the diet of kittiwakes in greenland; however, to our knowledge, severe breeding failure has not been reported from greenlandic colonies. future surveys may show if the reduced hunting season will have an effect on the size of the breeding population. other questions that are vital to address in greenland include reproduction success, diet, impacts of climate change, etc., data which are also relevant for the management of the population. we therefore strongly recommend that a kittiwake monitoring programme is initiated in greenland. acknowledgements we thank the danish nature protection agency for financial support for the kittiwake surveys in 2005 and 2006 (journal no. 127/001-0192). we are grateful to birger knudsen for providing up-to-date kittiwake information from the paamiut area, and to kasper johansen and morten bjerrum (national environmental research institute) for gis support. for safe navigation during the recent ship-based kittiwake surveys, we thank finn steffens (2005), naimmanngitsoq petersen (2006) and jens kjeldsen (2007), and leif petersen, danish air survey, was an excellent pilot during the aerial surveys in east greenland in 2008. thanks also to aevar petersen for icelandic literature, and to morten frederiksen, as well as two reviewers, for improving this manuscript. references anker-nilssen t., bakken v., strøm h., golovkin a.n., bianki v.v. & tatarinkova i.p. 2000. the status of marine birds breeding in the barents sea region. norsk polarinstitutt rapportserie 113. tromsø: norwegian polar institute. baird p.h. 1990. influence of abiotic factors and prey distribution on diet and reproductive success in three seabird species in alaska. ornis scandinavica 21, 224–235. bakken v., boertmann d., mosbech a., olsen b., petersen a., strøm h. & goodwin h. 2006. nordic seabird colony databases. results of a nordic project on seabird breeding colonies in faroes, greenland, iceland, jan mayen and svalbard. temanord 2006: 512. copenhagen: nordic council of ministers. barrett r.t., lorentsen s.-h. & anker-nilssen t. 2006. the status of breeding seabirds in mainland norway. atlantic seabirds 8, 97–126. boertmann d. 2004. seabird colonies and moulting harlequin ducks in south greenland. results of a survey in july 2003. research notes from neri 191. roskilde, denmark: national environmental research institute. boertmann d. 2006. optœlling af ridekolonier i disko bugt, arfersiorfik fjord og nordre strømfjord i 2005. (survey of kittiwake colonies in disko bay, arfersiorfik fjord and nordre strømfjord in 2005.) arbejdsrapport fra dmu 225. roskilde, denmark: national environmental research institute. boertmann d. 2007. grønlands rødliste 2007. (the greenland red list 2007.) roskilde, denmark: national environmental research institute. boertmann d. 2008. the lesser black-backed gull, larus fuscus, in greenland. arctic 61, 129–133. boertmann d., mosbech a., falk k. & kampp k. 1996. seabird colonies in western greenland (60°–79°30� n. lat.). technical report 170. roskilde, denmark: national environmental research institute. boertmann d., olsen k. & nielsen r.d. 2009. seabirds and marine mammals in northeast greenland. technical report 721. roskilde, denmark: national environmental research institute, aarhus university. bornaechea p.g. & gardarsson a. 2006. fuglabjörg á snæfellsnesi árid 2005. (seabird colonies in snæfellsnesi in 2005.) bliki 27, 51–54. boulinier t., danchin e., monnat j.y., doutrelant c. & cadiou b. 1996. timing of prospecting and the value of information in a colonial breeding bird. journal of avian biology 27, 252–256. burnham w., burnham k.k. & cade t.j. 2005. past and present assessments of bird life in uummannaq district, west greenland. dansk ornitologisk forenings tidsskrift 99, 196–208. cadiou b. & monnat j.y. 1996. parental attendance and squatting in the kittiwake rissa tridactyla during the rearing period. bird study 43, 164–171. carscadden j.e., montevecchi w.a., davoren g.k. & nakashima b.s. 2002. trophic relationships among capelin (mallotus villosus) and seabirds in a changing ecosystem. ices journal of marine science 59, 1027–1033. cramp s. & simmons k.e.l. (eds.) 1983. the birds of the western palearctic. vol. 3. oxford: oxford university press. ekker m. (ed.) 2008. vest-nordiske sjøfugler i et presset havmiljø. (west nordic seabirds in a marine environment under pressure.) kittiwake population status in greenlanda.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 397 temanord 2008:573. copenhagen: nordic council of ministers. frederiksen m., wanless s., harris m.p., rothery p. & wilson l.j. 2004. the role of industrial fisheries and oceanographic change in the decline of north sea black-legged kittiwakes. journal of applied ecology 41, 1129–1139. furness r.w. & tasker m.l. 2000. seabird-fishery interactions: quantifying the sensitivity of seabirds to reductions in sandeel abundance, and identification of key areas for sensitive seabirds in the north sea. marine ecology progress series 202, 253–264. gardarsson a. 2006. nýlegar breytingar á fjölda íslenskra bjargfugla. (recent changes in numbers of icelandic colonial seabirds.) bliki 27, 13–27. gaston a.j., bertram d.f., boyne a.w., chardine j.w., davoren g., diamond a.w., hedd a., montevecchi w.a., hipfner j.m., lemon m.j.f., mallory m.l., rail j.-f. & robertson g.j. 2009. changes in canadian seabird populations and ecology since 1970 in relation to changes in oceanography and food webs. environmental reviews 17, 267–286. gilg o. (ed.). 2005. ecopolaris—tara 5 expedition to ne greenland 2004. francheville, france: groupe de recherches en ecologie arctique. government of greenland 2002. hjemmestyrets bekendtgørelse nr. 38 af 6. december 2001 om beskyttelse af fugle. (executive order no. 38 of 6 december 2001 on the protection of birds.) nuuk: government of greenland. hansen b.u., sigsgaard c., rasmussen l., cappelen j., hinkler j., mernild s.h., petersen d., tamstorf m.p., rasch m. & hasholt b. 2008. present-day climate at zackenberg. in h. meltofte et al. (eds.): high-arctic ecosystem dynamics in a changing climate. pp. 111–149. amsterdam: elsevier. hatch s.a., byrd g.v., irons d.b. & hunt g.l. 1993. status and ecology of kittiwakes (rissa tridactyla and r. brevirostris) in the north pacific. in k. vermeer et al. (eds.). the status, ecology and conservation of marine birds in the north pacific. pp. 140–153. ottawa: canadian wildlife service special publication. hatch s.a. & hatch m.a. 1988. colony attendance and population monitoring of black-legged kittiwakes on the semidi islands, alaska. condor 90, 613–620. hatch s.a., robertson g.j. & baird h.p. 2008. black-legged kittiwake (rissa tridactyla). in a. poole (ed.): the birds of north america online. ithaca, ny: cornell laboratory of ornithology. hvidegaard s.m., forsberg r., hanson s., skourup h. & pedersen l.t. 2008. sea ice conditions off nw and ne greenland from satellite measurements, airborne and in-situ data: contract report for greenland bureau of minerals and petroleum. copenhagen: national space institute and center for oceans and ice, danish meteorological institute. johannessen o.m., bengtsson l., miles m.w., kuzmina s.i., semenov v.a., alekseev g.v., nagurnyi a.p., zakharov v.f., bobylev l.p., pettersson l.h., hasselmann k. & cattle h.p. 2004. arctic climate change: observed and modeled temperature and sea-ice variability. tellus series a 56, 328–341. kampp k. 1990. the thick-billed murre population of the thule district, greenland. arctic 43, 115–120. kampp k., nettleship d.n. & evans g.h. 1994. thick-billed murres of greenland: status and prospects. in d.n. nettleship et al. (eds.): seabirds on islands, threats, case-studies and action plans. pp. 133–154. cambridge: birdlife international. lyngs p. 2003. black-legged kittiwake rissa tridactyla recoveries. dansk ornitologisk forenings tidskrift 97, 92–100. mallory m.l., akearok j.a. & gaston a.j. 2009. status of high arctic black-legged kittiwake (rissa tridactyla) colonies in barrow strait, nunavut, canada. arctic 62, 96–101. mavor r.a., heubeck m., schmitt s. & parsons m. 2006. seabird numbers and breeding success in britain and ireland, 2006. uk conservation report 31. petersborough: joint nature conservation committee. merkel f.r. 2004. evidence of population decline in common eiders breeding in western greenland. arctic 57, 27–36. merkel f. & barry t. (eds.) 2008. seabird harvest in the arctic. caff technical report 16. akureyri: conservation of arctic flora and fauna international secretariat. merkel f.r., labansen a.l. & witting l. 2007. monitering af lomvier og rider i qaanaaq kommune, 2006. (monitoring of thick-billed murre and kittiwakes in the municipality of qaanaaq, 2006.) teknisk rapport 69. pinngortitaleriffik: greenland institute of natural resources. merkel f.r., rasmussen l.m. & rosing-asvid a. 2010. seabirds and marine mammals in south and southeast greenland, june 2008. technical report 81. pinngortitaleriffik: greenland institute of natural resources. mitchell p.i., newton s.f., ratcliffe n. & dunn t.e. 2004. seabird populations of britain and ireland. london: t. & a.d. poyser. nyeland j. 2004. apparent trends in the black-legged kittiwake in greenland. waterbirds 27, 342–349. nyeland j. 2007. monitering af lomviekolonierne kippaku og apparsuit i det nordlige upernavik, 2002. (monitoring the thick-billed murre colonies kippaku and apparsuit in northern upernavik.) teknisk rapport 65. pinngortitaleriffik: greenland institute of natural resources. nyeland j. & mathæussen h. 2004. monitering af havfuglekolonier i maniitsoq kommune 2003. (monitoring seabird colonies in the municipality of maniitsoq 2003.) teknisk rapport 59. pinngortitaleriffik: greenland institute of natural resources. regehr h.m. & montevecchi w.a. 1997. interactive effects of food shortage and predation on breeding failure of black-legged kittiwakes: indirect effects of fisheries activities and implications for indicator species. marine ecology progress series 155, 249–260. sunnanå k. & fossheim m. 2008. forvaltningsplan barentshavet—rapport fra overvåkingsgruppen 2008. (management plan barents sea—report from the monitoring group.) fisken og havet special issue 1b. bergen: institute of marine research. kittiwake population status in greenland a.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd398 appendix latest count of all registrated breeding colonies of black-legged kittiwakes in greenland. based on data from the seabird breeding colony database maintained by the national environmental research institute. in west greenland, the area name is listed by municipality. in east greenland the area name is listed by name of site. area colony number date qualitya unitb min pairsc north qaanaaq 77002 25 july 2006 h p 12 860 qaanaaq 76014 27 july 2006 h p 18 707 qaanaaq 76013 28 july 2006 h p 2457 qaanaaq 76012 29 july 2006 h p 1642 north-west upernavik 73069 16 july 1998 l i 10 upernavik 73056 8 july 2007 h n 43 upernavik 73043 8 july 2007 h n 152 upernavik 73026 6 july 2007 h n 13 upernavik 73025 6 july 2007 h n 13 upernavik 73011 6 july 2007 h n 608 upernavik 73010 31 july 2002 h i 437 upernavik 73009 1 august 2002 h i 2186 upernavik 73008 6 july 2007 h n 219 upernavik 73007 5 july 2007 h n 0 upernavik 72151 13 july 1999 h n 2 upernavik 72140 13 july 1999 h n 2 upernavik 72137 15 july 1998 h n 16 upernavik 72096 7 july 1998 h n 26 upernavik 72092 13 july 1998 l i 20 upernavik 72083 16 july 1998 l i 65 upernavik 72078 15 july 1998 h n 57 upernavik 72047 12 july 1998 m p 0 upernavik 72038 13 july 1998 l i 65 upernavik 72037 11 july 2007 h n 0 upernavik 72036 4 july 1998 h n 8 upernavik 72035 1 july 2007 h n 130 upernavik 72034 1 july 2007 h n 12 upernavik 72033 14 july 1998 l i 7 upernavik 72032 13 july 1998 h n 9 upernavik 72031 13 july 1998 l i 39 upernavik 72027 1 july 2007 h n 48 upernavik 72026 18 july 1994 m p 0 upernavik 72025 11 july 2007 m n 104 upernavik 72024 13 july 1998 m p 0 upernavik 72023 4 july 1998 m p 0 upernavik 72022 14 july 2000 m p 0 upernavik 72020 13 july 1998 h n 0 upernavik 72018 13 july 1998 h n 192 upernavik 72017 1 july 2007 h n 3 upernavik 72016 8 july 1998 m p 0 upernavik 72014 9 july 2007 h n 994 upernavik 72013 26 july 1999 h n 83 upernavik 72011 26 july 1999 h n 145 upernavik 72009 28 june 2007 h i 465 upernavik 72008 8 july 2008 h n 0 upernavik 72005 9 july 1999 h n 57 uummannaq 72002 10 july 2000 h i 228 uummannaq 71090 18 july 2000 h n 6 uummannaq 71087 18 july 2000 h n 80 uummannaq 71086 18 july 2000 h n 4 kittiwake population status in greenlanda.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 399 appendix continued area colony number date qualitya unitb min pairsc uummannaq 71084 18 july 2000 h n 21 uummannaq 71050 18 july 2000 h n 60 uummannaq 71026 16 july 2000 h p 0 uummannaq 71025 16 july 2000 h n 125 uummannaq 71023 18 july 2000 h n 4 uummannaq 71015 2 july 2000 m n 180 uummannaq 71011 13 july 2000 h p 0 uummannaq 71010 13 july 2000 h p 0 uummannaq 71009 13 july 2000 h n 2 uummannaq 71008 13 july 2000 h p 0 uummannaq 71007 13 july 2000 h p 0 uummannaq 70114 13 july 2000 h p 0 uummannaq 70113 13 july 2000 h p 0 uummannaq 70112 13 july 2000 h n 2 uummannaq 70111 12 july 2000 h p 0 uummannaq 70109 12 july 2000 h p 0 uummannaq 70106 15 july 2000 h p 0 uummannaq 70101 13 july 2000 h p 0 uummannaq 70099 13 july 2000 h p 0 uummannaq 70098 13 july 2000 h p 0 uummannaq 70097 12 july 2000 m p 0 uummannaq 70095 12 july 2000 h p 0 uummannaq 70090 12 july 2000 h p 0 uummannaq 70088 12 july 2000 h p 0 uummannaq 70086 8 july 2000 h p 0 uummannaq 70079 8 july 2000 h p 0 uummannaq 70072 8 july 2000 h p 0 uummannaq 70069 8 july 2000 h p 0 uummannaq 70068 8 july 2000 h p 0 uummannaq 70065 8 july 2000 h p 0 uummannaq 70064 12 july 2000 h p 0 uummannaq 70053 15 july 2000 h p 0 uummannaq 70049 15 july 2000 h p 0 uummannaq 70042 7 july 2000 h p 0 uummannaq 70026 4 july 2000 h n 20 qeqertarsuaq 70005 3 september 1995 l i 65 qeqertarsuaq 69116 15 july 2001 h 0 qeqertarsuaq 69064 22 july 2001 l n 10 qeqertarsuaq 69063 15 july 2001 h 0 qeqertarsuaq 69001 11 july 2005 m p 0 qeqertarsuaq 68012 11 july 2005 l p 0 ilulissat 69129 7 july 2005 h p 15 ilulissat 69118 6 july 2005 h p 0 ilulissat 69103 5 july 2004 m p 0 ilulissat 69081 6 june 2007 h n 0 ilulissat 69077 5 july 2005 h n 1 ilulissat 69049 5 july 2005 m p 2783 ilulissat 69048 6 july 2005 h n 90 ilulissat 69046 6 july 2005 h 0 ilulissat 69045 6 july 2005 h n 42 ilulissat 69043 6 july 2005 h n 44 ilulissat 69042 6 july 2005 h 0 ilulissat 69041 6 july 2005 h n 210 ilulissat 69040 7 july 2005 h n 18 ilulissat 69039 7 july 2005 h n 136 ilulissat 69038 6 july 2005 h p 7072 kittiwake population status in greenland a.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd400 appendix continued area colony number date qualitya unitb min pairsc ilulissat 69037 6 july 2005 m n 1077 ilulissat 69036 6 july 2005 h 0 ilulissat 69035 6 july 2005 m p 800 ilulissat 69034 6 july 2005 h p 0 ilulissat 69033 6 july 2005 h p 9514 ilulissat 69032 7 july 2005 h n 45 ilulissat 69030 7 july 2005 h n 27 ilulissat 69028 7 july 2005 h 0 ilulissat 69027 7 july 2005 h n 111 ilulissat 69026 7 july 2005 h p 0 ilulissat 69025 7 july 2005 h 0 ilulissat 69022 8 july 2005 h i 0 ilulissat 69020 5 july 2005 h 0 ilulissat 69019 5 july 2005 h 0 ilulissat 69018 5 july 2005 h 0 ilulissat 69017 4 july 2005 h 0 ilulissat 69016 4 july 2005 h 0 ilulissat 69015 4 july 2005 h n 49 ilulissat 69014 4 july 2005 h 0 ilulissat 69011 5 july 1976 i 0 ilulissat 69010 5 july 1976 p 0 ilulissat 69007 6 july 1976 m p 0 ilulissat 69003 5 july 1976 i 0 ilulissat 68036 6 july 1976 p 0 ilulissat 68035 6 july 1976 m p 0 qasigiannguit 68209 8 july 2005 h i 1 qasigiannguit 68203 9 july 2005 h n 314 qasigiannguit 68138 9 july 2005 h n 1 qasigiannguit 68112 9 july 2005 h n 2 qasigiannguit 68106 26 june 1976 i 0 qasigiannguit 68081 23 july 1997 m p 0 qasigiannguit 68054 21 july 2005 h p 0 qasigiannguit 68026 8 july 2005 h 0 qasigiannguit 68025 8 july 2005 h 0 qasigiannguit 68020 8 july 2005 h p 5 qasigiannguit 68017 8 july 2005 h p 0 qasigiannguit 68014 8 july 2005 h 0 aasiaat 68029 july 2006 m p 0 kangaatsiaq 68219 12 july 2005 h n 3 kangaatsiaq 68202 19 july 2005 h n 9 kangaatsiaq 68159 14 july 2005 h p 85 kangaatsiaq 68158 14 july 2005 h n 195 kangaatsiaq 68129 20 july 2005 h p 0 kangaatsiaq 68123 14 july 2005 h n 84 kangaatsiaq 68121 19 july 2005 h n 12 kangaatsiaq 68095 14 july 2005 h p 0 kangaatsiaq 68094 14 july 2005 h p 0 kangaatsiaq 68093 14 july 2005 h p 0 kangaatsiaq 68086 13 july 2005 h p 0 kangaatsiaq 68085 13 july 2005 h n 59 kangaatsiaq 68084 13 july 2005 h n 243 kangaatsiaq 68083 13 july 2005 h n 14 kangaatsiaq 68082 24 july 1997 m p 0 kangaatsiaq 68079 21 july 1997 m p 0 kangaatsiaq 68077 13 july 2005 h n 90 kangaatsiaq 68072 11 july 1954 m up 41 kittiwake population status in greenlanda.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 401 appendix continued area colony number date qualitya unitb min pairsc kangaatsiaq 68067 20 july 2005 h n 147 kangaatsiaq 68066 20 july 2005 h 0 kangaatsiaq 68065 20 july 2005 h p 0 kangaatsiaq 68061 21 july 2005 h p 0 kangaatsiaq 68059 21 july 2005 h p 0 kangaatsiaq 68058 21 july 2005 h p 0 kangaatsiaq 68055 21 july 2005 h p 0 kangaatsiaq 67062 19 july 2005 h 0 kangaatsiaq 67061 12 july 2005 h p 1 kangaatsiaq 67060 12 july 2005 h 0 kangaatsiaq 67059 12 july 2005 h 0 kangaatsiaq 67030 16 july 2006 h n 38 kangaatsiaq 67027 16 july 2006 h n 5 kangaatsiaq 67026 16 july 2006 h 0 kangaatsiaq 67025 16 july 2006 h n 37 kangaatsiaq 67024 16 july 2006 m p 0 kangaatsiaq 67011 16 july 2005 h n 2 south-west sisimiut 67017 16 july 2005 h 0 sisimiut 67015 16 july 2005 h 0 sisimiut 67014 16 july 2005 h 0 sisimiut 66201 28 august 1993 l p 50 sisimiut 66028 20 july 1975 m 0 maniitsoq 66044 22 july 2003 n 118 maniitsoq 66043 22 july 2003 n 23 maniitsoq 66021 28 june 1992 m p 0 maniitsoq 66008 22 july 2003 n 10 maniitsoq 66007 22 july 2003 n 67 maniitsoq 66005 22 july 2003 n 39 maniitsoq 66003 22 july 2003 m p 0 maniitsoq 66002 22 july 2003 n 14 maniitsoq 66001 21 july 2003 n 502 maniitsoq 65064 26 july 2003 h n 1205 maniitsoq 65043 1980 m p 50 maniitsoq 65036 22 july 2003 n 103 maniitsoq 65030 22 july 2003 n 43 maniitsoq 65029 22 july 2003 n 41 maniitsoq 65028 22 july 2003 n 164 maniitsoq 65027 22 july 2003 m p 0 maniitsoq 65026 22 july 2003 n 12 maniitsoq 65024 22 july 2003 m p 0 maniitsoq 65023 22 july 2003 n 48 maniitsoq 65022 22 july 2003 n 20 maniitsoq 65021 22 july 2003 n 27 maniitsoq 65019 21 july 2003 h n 11 337 maniitsoq 65018 21 july 2003 n 34 maniitsoq 65015 25 july 2003 h n 3930 maniitsoq 65013 25 july 2003 h n 1730 maniitsoq 65012 25 july 2003 m p 0 maniitsoq 65011 25 july 2003 h n 1390 maniitsoq 65010 25 july 2003 m p 0 maniitsoq 65009 25 july 2003 h n 3393 maniitsoq 65008 25 july 2003 h n 715 maniitsoq 65004 26 july 2003 h n 2400 maniitsoq 65003 26 july 2003 h n 4770 maniitsoq 65002 26 july 2003 h n 130 kittiwake population status in greenland a.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd402 appendix continued area colony number date qualitya unitb min pairsc maniitsoq 65001 26 july 2003 h n 100 maniitsoq 64200 4 july 1992 h p 6 nuuk 64035 28 june 2007 h p 48 nuuk 64023 6 july 1986 m p 0 nuuk 64022 27 june 2007 m p 276 nuuk 64019 13 july 2007 m p 302 nuuk 64018 27 june 2007 m p 217 nuuk 64016 2 july 2007 0 nuuk 64015 13 july 2007 m p 62 south paamiut 62018 26 july 2007 h p 437 paamiut 62010 22 july 2007 h n 0 paamiut 62003 22 july 2007 h n 41 paamiut 62001 26 july 2007 h p 0 paamiut 61028 26 july 2003 h n 0 paamiut 61009 26 july 2007 h p 697 paamiut 61007 july 2003 m p 0 paamiut 61002 26 july 2003 m n 2120 qaqortoq 60087 28 july 2003 m n 81 qaqortoq 60016 28 july 2003 m n 95 qaqortoq 60012 1 august 1999 m n 12 narsaq 61040 28 july 2003 m n 33 narsaq 61039 28 july 2003 m n 22 narsaq 61038 28 july 2003 m n 110 narsaq 61010 28 july 2003 l 0 narsaq 60015 28 july 2003 m n 134 nanortalik 60044 16 july 2003 h n 32 nanortalik 60028 16 july 2003 h n 3 nanortalik 60027 16 july 2003 h n 25 nanortalik 60001 18 july 2003 h n 5 north-east mallemukfjeld 80501 july 1993 h n 873 fugleø 76528 16 august 2003 l i 7 rødeø 76524 16 august 2003 l i 5 maroussia 76508 29 july 2008 l n 50 hvalros ø 74512 24 july 2008 h n 75 hvalros ø 74511 24 july 2008 h n 30 hvalros ø 74502 24 july 2008 m n 40 kangikajik 70508 9 july 2004 h n 1300 immikkeertikajik 70507 23 july 2004 h n 600 appalik 70505 23 july 2004 h n 450 sulussuutikajik 69503 26 july 2008 l n 50 dunholm 69502 26 july 2008 h n 57 southeast umiivik 64501 18 july 1933 small colony taateraat 61501 18 june 2008 m i 97 west of kap discard 60502 16 june 2008 m i 39 kangerlussuatsiaq 60501 1 june 2008 l 0 a l, low; m, medium; h, high. b the original unit for which the count number was given. i, individual; n, nest; p, pair. c number of individuals were converted to number of breeding pairs using a factor of 0.65. kittiwake population status in greenlanda.l. labansen et al. polar research 29 2010 391–403 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 403 kekonen.indd 33kekonen et al. 2005: polar research 24(1–2), 33–40 volcanic ash particles are commonly detected from ice cores because of their importance for dating (e.g. grönvold et al. 1995; zielinski et al. 1997). volcanic eruptions usually produce large volumes of so2 gas, dust, lava, ash and rock (thordarson et al. 2001). volcanic material can travel high into the atmosphere and mix with air masses, which can spread very widely. this material is eventually scavenged in precipitation, or deposited dry in very arid regions. volcanic tephra includes all rock and lava particles that are erupted into the air, regardless of particle size. in addition to volcanic ash particles, tephra contains other larger sand and rock particles. ash and other small particles can travel long distances, but bigger sand particles are much heavier than ash and are deposited much closer to the eruption site. volcanic ash is the smallest tephra fragment (< 2 mm) composed of silicon, aluminium, iron, calcium, magnesium, sodium and other trace elements. each volcanic eruption produces volcanic ash particles with a specifi c signature in these elements, thereby producing a chemical fi ngerprint by which it can be identifi ed the icelandic laki volcanic tephra layer in the lomonosovfonna ice core, svalbard teija kekonen, john moore, paavo perämäki & tõnu martma the largest sulphuric acid event revealed in an ice core from the lomonosovfonna ice cap, svalbard, is associated with the densest concentration of microparticles in the ice core at 66.99 m depth. electron microscope analysis of a volcanic ash particle shows it has the same chemical composition as reported for debris from the eruption of iceland’s laki fi ssure in 1783 and confi rms the identifi cation of the tephra. most of the particles in the deposit are not ash, but are common sand particles carried aloft during the eruption event and deposited relatively nearby and downwind of the long-lasting eruption. the tephra layer was found 10 20 cm deeper than high sulphate concentrations, so it can be inferred that tephra arrived to lomonosovfonna about 6 12 months earlier than gaseous sulphuric acid precipitation. the sulphuric acid spike has a signifi cant cooling impact recorded in the oxygen isotope profi le from the core, which corresponds to a sudden drop in temperature of about 2 °c which took several years to recover to previous levels. these data are the fi rst particle analyses of laki tephra from svalbard and confi rm the identifi cation of the large acidic signal seen in other ice cores from the region. they also confi rm the very large impact that this icelandic eruption, specifi cally the sulphuric acid rather than ash, had on regional temperatures. t. kekonen, university of oulu, box 3000, fi-90014 university of oulu, finland and arctic centre, university of lapland, box 122, fi-96101 rovaniemi, finland, teija.kekonen@oulu.fi ; j. moore, arctic centre, university of lapland, box 122, fi-96101 rovaniemi, finland; p. perämäki, dept. of chemistry, university of oulu, box 3000, fi-90014 university of oulu, finland; t. martma, institute of geology, tallinn university of technology, estonia pst 7, ee-10143 tallinn, estonia. 34 the laki tephra layer in the lomonosovfonna ice core (e.g. palais et al. 1992; grönvold et al. 1995; zielinski et al. 1997; zielinski et al. 1998). the eruption of iceland’s laki fracture in 1783 was one of largest basaltic fi ssure eruptions in recorded history. the volume of aerosols injected into the atmosphere by the eruption was one of the greatest atmospheric pollution events over europe during historic times (thordarson & self 2003). the laki volcanic eruption lasted for eight months (june 1783 to february 1784) and produced one of the largest recorded basaltic lava fl ows in iceland. the sulphuric and, especially, the hydrofl uoric acid produced by the eruption were responsible for the deaths of more than half the animals on iceland (thordarson & hoskuldsson 2002). there were also widespread effects in the northern hemisphere, including cooling (thordarson & hoskuldsson 2002; highwood & stevenson 2003; thordarson & self 2003). a strong sulphate acid signal corresponding to an age of 1783–84 has been reported in many ice cores from greenland and svalbard (fiacco et al. 1994; zielinski et al. 1994; thordarson et al. 1996; watanabe et al. 2001; thordarson & self 2003). in this work we have analysed samples close to a major sulphate peak in the ice core and found a particle-rich layer at a depth of 66.99 m using sem-eds. this is the fi rst published result relating to the tephra layer and volcanic ash particle from the laki eruption located in svalbard glaciers. study site and methods the 121 m long ice core was recovered with an electromechanical drill from the summit of the lomonosovfonna ice cap (1255 m a.s.l.), on the island of spitsbergen, svalbard, in 1997 (fig. 1) (isaksson et al. 2001). total ice depth from radar sounding was 123 m, and the site is close to the highest point of the ice cap with roughly radial ice fl ow. the ice core represents an approximately 800 year period. the time scale of the core was based on an ice layer thinning model (nye 1963) tied with the known dates of prominent reference horizons (1963 radioactive layer and 1783 laki volcanic sulphate layer and volcanic ash particle; see kekonen et al. [2005] for details). the accumulation rate for the 1997–1963 period is 0.41 m water equivalent per year and a somewhat lower value of 0.31 m w.e. per year for the period 1963– 1783. the model age profi le can be independently checked by comparison with automated seasonal cycle counting in stable isotopes and ions down to 81 m (pohjola et al. 2002). the model age at 81 m depth is 1705, while the cycle counting method gives a date of 1715. there is a thus a discrepancy of 10 years in about 75 years between the laki horizon and the limit of cycle counting. however, the cycle counting method will always tend to miss a fraction of low accumulation rate years due to the resolution of the data and isotope diffusion effects, so a good model dating should be more reliable (on average) than cycle counting. the current annual temperature range is from 0 °c to about –40 °c. any summer meltwater is refrozen mostly within the previous winter’s snow, and the remainder within the next two or three lower annual layers. although percolation can be up to eight years in the warmest years in the 20th century, it was much reduced during the little ice age (kekonen et al. 2005). various statistical analytical methods (see kekonen fig 1. map showing svalbard and iceland and the inferred plume direction of the westerly jet stream on 10 june 1783. transport paths are based on the data of thordarson & self (2003) and fiacco et al. (1994). 35kekonen et al. 2005: polar research 24(1–2), 33–40 et al. 2005; moore et al. 2005) show that chemical and isotopic stratigraphy are suffi ciently well preserved that signifi cant decadal-scale periodicities can be found, annual layers can be counted for about 300 years, and changes in chemical composition related to changes in climate are far more signifi cant than changes in chemical composition in ice layers subject to various degrees of percolation. the core was transported and stored in a frozen state (–22 °c). the whole ice core was cut into 5 cm sections and the outer parts of the samples were removed in a cold room under a laminar fl ow hood. for particle analyses, selected samples were melted and fi ltered under a laminar fl ow hood. the 10 20 ml of meltwater was fi ltered just after melting with nuclepore polycarbonate membranes (25 mm diameter and 0.2 mm pore size) using a vacuum fi lter system. each sample was fi ltered through separate fi lter membranes. filter membranes were glued onto the stubs using carbon-coated double-sided tape and coated with a thin fi lm of carbon. samples were analysed for major elements using a jeol jms-6400 scanning electron microscope combined with a link isis and inca energy dispersive spectrometer. an acceleration voltage of 15 kv and a beam current of 1.2 na were used for the sem-eds (scanning electron microscope energy dispersive spectrometer) analysis with the sample distance of 15 mm. acidity was measured using a radiometer copenhagen phm 205 ph meter and xc 161 combined ph electrode. for acidity measurements, samples were melted under nitrogen atmosphere to prevent carbon dioxide dissolution. all the ions (na+, k+, nh4+, mg2+, ca2+, cl–, no3–, so42–, ch3so3–) were analysed over the whole core in 5 10 cm resolution using a dionex ion chromatograph with conductivity detector and suppressor housed in a clean laboratory. details for ion chromatography analyses are described by kekonen et al. (2002) and kekonen et al. (2004). δ18o was determined using a finnigan-mat delta-e mass spectrometer (isaksson et al. 2001). results are measured against laboratory internal standard water, which has been calibrated on the v-smow/slap scale using the international reference materials v-smow (vienna standard mean oceanic water) and slap (standard light antarctic precipitation) from the international atomic energy agency. reproducibility of replicate analyses is generally better than ± 0.1 ‰. we used an automated particle analyser to measure the chemical composition of all the particles present on a 271 × 191 mm subsections of the 490 mm2 fi lter membrane. in total we analysed 2063 particles in 44 different subsections of the same fi lter membrane. results and discussion there are no visible dust or tephra bands in the ice core, but particles were sought at many depths using the method described above. enormous amounts of tephra (approximately half a million particles) were detected on the 66.99 67.04 m depth fi lter membrane. the subsection typically contained 30 100 particles, most commonly 50. (for comparison, at other depths a subsection usually contained less than 10 particles.) this is the only depth where tephra were found close to a high sulphate and acidity peak (66.69 66.89 m) (fig. 2). most of the tephra were small sand particles of basaltic composition (fig. 3). the sio2 composition is approximately same as in particles originating from laki eruption as reported in the literature (see references in table 1). while the automated analyses in fig. 3 do not give very exact chemical compositions due to the nature of the particle morphology, the large numbers of analyses give a statistical view of tephra composition relative to the composition of the laki tephra. a volcanic ash particle (that is, an amorphous glassy shard indicative of volcanic eruption activity) was found amongst the many sand particles (fig. 4) and was analysed in detail using a spot analyser at 40 points on the particle. comparison of the chemical composition of the particle with the composition of tephra from known eruptions indicates that particles found in the lomonosovfonna ice core originate from the volcanic eruption of laki in 1783 (table 1). the tephra (including sand and ash) was ejected into the atmosphere by the fi ssure eruption mechanism that is typifi ed by the laki eruption (fiacco et al. 1994). atmospheric transport directed the laki aerosol plume fi rst to the east and the north-east (thordarson & self 2003) (fig. 1). since svalbard is rather near to iceland—less than 2000 km—and generally downwind of it, many heavy sand particles in addition to ash particles are observed in the core. the volcanic tephra layer is about 10 20 cm deeper than the high sulphate concentration and acidity peaks (seen between 66.69 and 66.89 m) 36 the laki tephra layer in the lomonosovfonna ice core (fig. 2). at this depth (66 67 m), the 5 cm sample resolution roughly corresponds to few months of time. this indicates that the volcanic tephra was carried to lomonosovfonna ice cap about 3 9 months before the sulphuric acid started to precipitate on the glacier, and 6 12 months before the main sulphuric acid precipitation occurred. sulphuric acid precipitation on the lomonosvfonna ice cap lasted for 9 15 months. ecm analyses of greenland ice cores (clausen et al. 1997) indicate that the fallout from the laki eruption lasted 1.0 and 1.6 years there. after the main sulphate concentration and acidity peaks, a smaller peak can also be observed (figs. 2, 5). thordarson et al. (1996) reported that high discharge basaltic eruptions, such as fig. 2. sulphate (thick line) concentrations and acidity (thin line) near the laki peak. the tephra layer is marked by the thick black vertical line. table 1. mean value and standard deviation for the 40 spot analysis of volcanic ash particle (fig. 4) compared to other laki particles. “ref. 1” is the composition of the glass phase of the laki eruption. an average of six samples and ten glass grains were analysed in each sample (. grönvold, pers. comm. 2002). refs. 2 and 3 are the composition of laki tephra (t. thordarson, unpubl. data; fiacco et al. 1994). ref. 4 is the composition of particles from fi lter paper collected from the gips2 ice core (fiacco et al. 1994). ref. 5 is the major element composition of laki glass (thordarson et al. 1996). the number of analyses is shown in the last column (n). wt. % na2o mgo al2o3 sio2 so3 k2o cao tio2 mno feo n mean 2.81 6.59 13.16 50.64 0.45 0.18 10.20 2.07 0.03 13.85 40 sd 0.50 0.65 0.56 1.09 0.22 0.12 1.17 0.23 0.09 1.50 ref. 1 2.61 5.32 12.70 49.10 0.47 10.10 2.96 0.24 13.70 ref. 2 2.78 5.40 13.26 49.97 0.44 9.90 3.02 0.21 14.08 18 sd 0.11 0.02 0.02 0.07 0.01 0.03 0.01 0.00 0.05 ref. 3 1.83 5.48 12.96 54.47 0.50 9.23 2.84 12.69 3 sd 0.18 0.47 1.56 1.05 0.01 0.59 0.35 1.01 ref. 4 1.26 4.81 13.05 52.26 0.69 10.41 2.88 14.64 5 sd 0.52 0.65 0.95 2.45 0.25 0.90 0.34 2.59 ref. 5 2.84 5.78 13.05 49.68 0.42 10.45 2.96 0.22 13.78 21 sd 0.12 0.30 0.48 0.36 0.05 0.28 0.17 0.03 0.61 37kekonen et al. 2005: polar research 24(1–2), 33–40 laki, are able to loft huge quantities of gas to altitudes (including the troposphere and lower stratosphere) where the resulting aerosol can reside for 1 2 years (stevenson et al. 2003). in greenland ice cores high sulphate peaks are observed in spring, summer and autumn 1784, indicating that the increased atmospheric loading of so2 lasted for about a year (fiacco et al. 1994; thordarson et al. 1996). the highest sulphate concentration observed in the greenland ice cores is about 1300 µg l–1 (fiacco et al. 1994), which is slightly lower than we observe in the lomonosvfonna ice core (fig. 2). the mean acidity of the laki signal is 18 ± 8 µg l–1. thordarson & self (2003) estimated the excess optical depth caused by the eruption relative to that due to the absolutely calibrated krakatau aerosol cloud with a correction for the different geographic extent of the volcanic clouds. the method requires only the mean amplitude of the acidity of the laki peak in greenland ice cores, and produces an excess optical depth of 0.8 ± 0.4. applying the same procedure to the lomonosovfonna acidity record results in an excess optical depth of 0.9 ± 0.4, which is in excellent agreement with thordarson & self (2003). clausen et al. (1997) report acidic fallout in central and southern greenland ice cores (147 and 177 kg km–2, respectively). this compares with a fallout preserved in the lomonosovfonna ice core of 390 kg km–2. this much larger fallout is a consequence of svalbard being virtually downwind of iceland during the eruption, while southern and, especially, central greenland were essentially upwind. the impact of the large acidity pulse on european temperatures has been well documented using various historical and proxy archives (thordarson & self 2003). the impact on the lomonosovfonna δ18o isotopic temperature proxy (isaksson et al. 2003) can be seen in fig. 5. it is clear that there is an immediate drop in δ18o following the acid deposition rather than the ash fallout recorded by the tephra layer deposit. there is a 0.8 ‰ dip in 3-year running means relative to 30-year running means in δ18o for the 3 years following the acidic fallout, and this represents the lowest value of δ18o between 1400 and the fig. 3. chemical compositions of 2063 particles by automated analysis in 44 different subsections of the membrane fi lter from a depth of 66.99 m. the box shows the chemical composition of laki volcanic ash particles from the literature cited in table 1. fig. 4. a volcanic ash particle from a depth of 66.99 m. 38 the laki tephra layer in the lomonosovfonna ice core 1820s, and may therefore be regarded as highly signifi cant. this is in contrast with the signal in the greenland ice cores, where either a modest rise in δ18o or no change is seen immediately following the eruption (vinther et al. 2003). however, this apparent discrepancy may be explained by the larger acidic fallout to the west of iceland over europe and svalbard, and the typical seesaw behaviour of the north atlantic oscillation, resulting in temperature anomalies of opposite sign over europe and greenland, (e.g. vinther et al. 2003). we can calibrate the δ18o–temperature relationship with borehole thermometry. van de wal et al. (2002) analysed the borehole temperature profi le, fi nding that temperatures in the 19th century were 2.4 °c colder than the 20th century. this compares with a 0.8 ‰ difference in δ18o (isaksson et al. 2003) between the 19th and 20th centuries—virtually the same depression as caused by the laki eruption. thus we can estimate that the 3 year dip in δ18o corresponds to about a 2.4 °c temperature fall. we could also use a calibration of isotopes against instrumental temperature records. however, extrapolating the calibrations to the colder pre-20th century period is unreliable (e.g. von storch et al. 2004), so we prefer to use the estimate based on the borehole temperature profi le. highwood & stevenson (2003) and thordarson & self (2003) observed in their calculations that temperature decreased 0.21 °c and 1.3 °c, respectively, in the wider northern hemisphere after the laki eruption. there are several reasons why the temperature drop in svalbard may have been higher than in mainland europe. it is clear that recovery to more normal temperatures takes at least two to three years (thordarson & self 2003). although the laki eruption probably did not eject aerosol into the upper stratosphere (stevenson et al. 2003), where long residence times are possible, the long-lasting nature of the eruption helped to produce a persistent temperature depression, at least over much of europe. the north atlantic sea surface temperatures during the period 1780–1820 were monitored by the british admiralty and are discussed by bjerknes (1964): the ocean south of 40° n was up to 3 °c warmer than the present climate, while the northerly parts were 2 3 °c cooler. this condition would readily lead to increased sea ice cover in the greenland, iceland and barents seas, providing a ready positive feedback mechanism for a year or two. feedbacks with the large-scale atmospheric circulation patterns similar to those found for more recent eruptions (kirchner et al. 1999) may also have enhanced the impact of the eruption. fig. 5. sulphate (thick line) concentrations and isotope δ18o value (thin line) as a proxy for temperature near the laki sulphate peak. the tephra layer is marked by the thick black vertical line. 39kekonen et al. 2005: polar research 24(1–2), 33–40 conclusions the insoluble fractions of ice core samples show that during the 1783 laki volcanic eruption massive amounts of tephra arrived to the lomonosovfonna ice cap in svalbard. the volcanic tephra layer includes large amounts of sand particles which suggests that not only light ash particles were well transported downwind from the eruption site. the heavy particles would also have been resistant to removal on the ice cap by wind. the tephra layer was found 10 20 cm deeper than high sulphate concentrations and acidity and shows that tephra arrived to the ice cap 6 12 months earlier than gaseous sulphur dioxide was rained out as sulphuric acid. the sulphuric acid precipitation lasted 9 15 months. analyses indicate that the geochemical compositions of the volcanic tephra are basaltic, and the geochemical signatures of an ash particle show derivation from the icelandic laki volcanic eruption in 1783. acknowledgements.—the authors thank the finnish forest research institute research station in rovaniemi for cold and clean room facilities and aslak grinsted for helpful analyses. the drilling of the lomonosovfonna 1997 ice core was fi nanced by the norwegian polar institute and the institute for marine and atmospheric research, utrecht. the laboratory work presented here was funded by the finnish academy figare project. elisabeth isaksson, veijo pohjola, roderik van de wal and all the fi eld participants are also thanked. references bjerknes, j. 1964: atlantic air–sea interaction. adv. geophys. 10, 1–82. clausen, h. b., hammer, c. u., hvidberg, c. s., dahl-jensen, d. & steffensen, j. p. 1997: a comparison of the volcanic records over the past 4000 years from the greenland ice core project and dye 3 greenland ice cores. j. geophys. res. 102(c12), 26707–26723. fiacco, r. j., thordarson, t., germani, m. s., self, s., palais, j. m., whitlow, s. & grootes, p. m. 1994: atmospheric aerosol loading and transport due to the 1783–84 laki eruption in iceland, interpreted from ash particles and acidity in the gisp2 ice core. quat. res. 42, 231–240. grönvold, k., óskarsson, n., johnsen, s. j., clausen, h. b., hammer, c. u., bond, g. & bard, e. 1995: ash layer from iceland in the greenland grip ice core correlatred with oceanic and land sediments. earth planet. sci. lett. 135, 149–155. highwood, e. j. & stevenson, d. s. 2003: atmospheric impact of the 1783–1784 laki eruption. part ii: climatic effect of sulphate aerosol. atmos. chem. phys. 3, 1177–1189. isaksson, e., hermanson, m., hicks, s., igarashi, m., kamiyama, k., moore, j. c., motoyama, h., muir, d., pohjola, v., vaikmäe, r. & van de wal, r. 2003: ice core from svalbard—useful archives of past climate and pollution history. phys. chem. earth 28, 1217–1228. isaksson, e., pohjola, v., jauhiainen, t., moore, j., pinglot, j. f., vaikmäe, r., van de wal, r. s. w., hagen, j. o., ivask, j., karlöf, l., martma, t., meijer, h. a. j., mulvaney, r., thomassen, m. & van den broeke, m. 2001: a new ice core record from lomonosovfonna, svalbard: viewing the data between 1920–1997 in relation to present climate and environmental conditions. j. glaciol. 47, 335–345. kekonen, t., moore, j., mulvaney, r., isaksson, e., pohjola, v. & van de wal, r. s. w. 2002: an 800 year record of nitrate from the lomonosovfonna ice core, svalbard. ann. glaciol. 35, 261–265. kekonen, t., moore, j., perämäki, p., mulvaney, r., isaksson, e., pohjola, v. & van de wal, r. s. w. 2005: the 800 year long ion record from the lomonosovfonna (svalbard) ice core. j. geophy. res. 110(d7), 10.1029/2004jd005223. kekonen, t., perämäki, p. & moore, j. c. 2004: comparison of analytical results for chloride, sulfate and nitrate obtained from adjacent ice core samples by two ion chromatographic methods. j. environ. monit. 6, 147–152. kirchner, i., stenchikov, g., graf, h.-f., robock, a. & antuna, j. 1999: climate model simulation of winter warming and summer cooling following the 1991 mount pinatubo volcanic eruption. j. geophys. res. 104(d16), 19039–19055. moore, j. c., a. grinsted, t., kekonen & pohjola, v. 2005: separation of melting and environmental signals in an ice core with seasonal melt. geophys. res. lett. doi:10.1029/ 2005gl023039 nye, j. f. 1963: correction factor for accumulation measured by the ice thickness of the annual layers in an ice sheet. j. glaciol. 4, 785–788. palais, j. m., germani, m. s. & zielinski, g. a. 1992: interhemispheric transport of volcanic ash from a 1259 a.d. volcanic eruption to the greenland and antarctic ice sheets. geophys. res. lett. 19, 801–804. pohjola, v. a., martma, t., meijer, h. a. j., moore, j. c., isaksson, e., vaikmäe, r. & van de wal, r. s. w. 2002: reconstruction of 300 years annual accumulation rates based on the record of stable isotopes of water from lomonosovfonna, svalbard. ann. glaciol. 35, 57–62. stevenson, d. s., johnson, c. e., highwood, e. j., gauci, v., collins, w. j. & derwent, r. g. 2003: atmospheric impact of the 1783–1784 laki eruption. part i: chemistry modelling. atmos. chem. phys. 3, 487–507. thordarson, t. & hoskuldsson, a. 2002: classic geology in europe. 3: iceland. herts, uk: terra publishing. thordarson, t., miller, d. j., larsen, g., self, s. & sigurdsson h. 2001: new estimates of sulphur degassing and atmospheric mass-loading by the 934 ad eldgjá eruption, iceland. j. volcan. geotherm. res. 108, 33–54. thordarson, t. & self, s. 2003: atmospheric and environmental effects of the 1783–1784 laki eruption: a review and reassessment. j. geophys. res. 108(d1), 4011–4039. thordarson, t., self, s., óskarsson, n. & hulsebosch, t. 1996: sulfur, chlorine, and fl uorine degassing and atmospheric loadings by the 1783–1784 ad laki (skaftár fires) eruption in iceland. bull. volcan. 58, 205–225. van de wal, r. s. w., mulvaney, r., isaksson, e., moore, j. c., pinglot, j.-f., pohjola, v. & thomassen, m. p. a. 2002: reconstruction of the historical temperature trend from measurements in a medium-length bore hole on the lono40 the laki tephra layer in the lomonosovfonna ice core mosovfonna plateau, svalbard. ann. glaciol. 35, 371–378. vinther, b. m., johnsen, s. j., andersen, k. k., clausen, h. b. & hansen, a. w. 2003: nao signal recorded in the stable isotopes of greenland ice cores. geophys. res. lett. 30, doi:10.1029/2002gl016193. von storch, h., zorita, e., jones, j. m., dimitriev, y., gonzález-rouco, f. & tett, s. f. b. 2004: reconstructing past climate from noisy data. science 306(5696), 10.1126/ science.1096109. watanabe, o., motoyama, h., igarashi, m., kamiyama, k., mat oba, s., goto-azuma, k., narita, h. & kameda, t. 2001: studies on climatic and environmental changes during the last hundred years using ice cores from various sites in nord aust landet, svalbard. mem. natl. inst. polar res. spec. iss. 54, 227–242. zielinski, g. a., fiacco, r. j., mayewski, p. a., meeker, l. d., whitlow, s., twickler, m. s., germani, m. s., endo, k. & yasui, m. 1994: climatic impact of the a.d. 1783 asama (japan) eruption was minimal: evidence from the gisp2 ice core. geophys. res. lett. 21, 2365–2368. zielinski, g. a. & germani, m. s. 1998: new ice-core evidence challenges the 1620s bc age for the santorini (minoan) eruption. j. archaeol. sci. 25, 279–289. zielinski, g. a., mayewski, p. a., meeker, l. d., grönvold, k., germani, m. s., whitlow, s., twickler, m. s. & taylor, k. 1997: volcanic aerosol records and tephrochronology of the summit, greenland, ice cores. j. geophys. res. 102(c12), 26 625–26 640. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <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> /nld <feff004700650062007200750069006b002000640065007a006500200069006e007300740065006c006c0069006e00670065006e0020006f006d0020005000440046002d0064006f00630075006d0065006e00740065006e0020007400650020006d0061006b0065006e0020006d00650074002000650065006e00200068006f00670065002000610066006200650065006c00640069006e00670073007200650073006f006c007500740069006500200076006f006f0072002000610066006400720075006b006b0065006e0020006d0065007400200068006f006700650020006b00770061006c0069007400650069007400200069006e002000650065006e002000700072006500700072006500730073002d006f006d0067006500760069006e0067002e0020004400650020005000440046002d0064006f00630075006d0065006e00740065006e0020006b0075006e006e0065006e00200077006f007200640065006e002000670065006f00700065006e00640020006d006500740020004100630072006f00620061007400200065006e002000520065006100640065007200200035002e003000200065006e00200068006f006700650072002e002000420069006a002000640065007a006500200069006e007300740065006c006c0069006e00670020006d006f006500740065006e00200066006f006e007400730020007a0069006a006e00200069006e006700650073006c006f00740065006e002e> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice the ecophysiology of under-ice fauna arne v. aarset aarset. a . v. 1991: the ecophysiology of under-ice fauna. pp. 309-324 in sakshaug, e . , hopkins, c . c . e . & 0ritsland, n.a. (eds.): proceedings of the pro mare symposium on polar marine ecology. trondheim. 12-16 may 1990. polar research l o ( 1 ) . during exposure to low salinity, the under-ice amphipods gammarus wilkitzkii and onisimus glacialis appeared as euryhaline osmoregulators. displaying regulation of haemolymph concentrations of sodium and chloride. free amino acids took part in the regulation. during freezing and brine formation, the amphipods were freeze-sensitive and did not tolerate being frozen into solid ice. however. they could stay in the vicinity of the ice, conforming osmotically to the ambient brine and thus lowering the melting point of the amphipods' body fluids. this prevented internal ice formation in the absence of antifreeze agents (thf) in the haemolymph. when g. wilkitzkii. 0. glacialis and apherusa glacialis were exposed to dilute seawater, elevated rates of oxygen consumption and ammonia excretion were observed. the 0 : n atomic ratio was kept nearly constant during hyposmotic stress, indicating protein/lipids as metabolic substrate. rates of oxygen consumption and ammonia excretion increased with increasing osmotic differences between the haemolymph and the medium. indicating higher energy requirements for osmotic and ionic regulation at low salinities. a minor decrease in haemolymph sodium concentrations coincided with the increased ammonia output during hyposmotic stress. indicating a possible counter ion regulation of nh: and na+. an increased rate of oxygen consumption, ammonia excretion and o : n ratio versus temperature was observed for all species. arne v . aorset'. department of zoology. universitv of trondheim. n-7055 dragiioll. norway. introduction polar sea ice is a habitat for under-ice biota (hor ner 1985). if these organisms are associated with the sea ice throughout the year, they will be exposed to seasonal changes in physical par ameters as the ice melts or freezes. it is clear that animals in intimate contact with the ice would benefit considerably from physiological and behavioural adaptations that permit them to sur vive freezing and thawing changes in their immediate environment. sea-ice initially forms when open water is exposed to cold air. at the ice/water interface of growing ice, salts are included as brine pockets in the ice (weeks 1968). in response to temperature change and internal stress, the pockets inter connect as brine channels, and about 50-300 chan nels per m2 may exist along the bottom of the ice (lake & lewis 1970; eide & martin 1975; niddrauer & martin 1979). as the arctic sea ice becomes thicker, the average bulk salinity of the ice decreases from 10-20%0 to about 4-8%0, indi cating a major loss of brine to the ocean (malm gren 1927; cox & weeks 1974). however, the volume and salinity of brine excluded from sea * present address: centre for environment and deuelopmenr. unruersiry of trodhelm. n-7055 trondheim. norway. ice depend on the growth rate of the ice and the salinity of the seawater (wakatsuchi & ono 1983). in the arctic, melting of the sea-ice surface begins as air temperatures approach freezing point with a development of melt ponds at the surface of the ice floes (nansen 1906). a large part of this meltwater flows further off the ice and into the sea. melt ponds which are charac teristic of melting ice in the arctic have rarely been seen in the antarctic (gordon 1981; maykut 1985) as antarctic pack ice melts predominantly at the ice/water interface (andreas & ackley 1982). in both polar regions the true under-ice (sym pagic) fauna is dominated by amphipods (carey 1985). the dominant species in the ice community of the arctic barents sea are apherusa glacialis, gammarus wilkitzkii and onisimus glacialis (gul liksen 1984; gulliksen & l ~ n n e 1989; aarset & aaunaas 1987a). in the antarctic weddell sea, the dominant species observed in the ice com munity were the amphipod eusirus antarcticus and the first juvenile stage of the krill euphausia superba (aarset & torres 1989). the micro distribution of these crustaceans in the under-ice habitats varies from species to species (carey 1985). individuals have been observed living in brine channels (cross 1982; newbury 1983) and 310 a . v . aarser partially or fully embedded in the ice (gulliksen 1984). green & steele (1975) reported that g a m maraconrhus loricatus was the only amphipod species associated with ice stalactites and may at times be frozen within them. in the weddell sea, e. antarcticus was found living in brine channels or at the ice/water interface and the first juvenile stage of the krill e . superba was observed feeding on ice algae (aarset 1988). during summer melt of the sea ice, the crus taceans are likely to encounter low salinity con ditions, and during sea-ice growth they will be exposed to low temperature and high salinity brine at the ice/water interface. the mechanisms of cold resistance and osmotic regulation of the animals will ultimately determine whether they must leave the sea ice or may stay and cope physiologically with the changing conditions. this topic was the first to be examined at the start of the pro mare program. the next question to be answered was. what would be the metabolic consequence of an adaptation of amphipods to the sea-ice environment? we have in our studies therefore recorded the metabolic responses (measured as the specific oxygen consumption and ammonia excretion) of the arctic amphipods exposed to various seawater salinities and tem peratures (aarset & aunaas 1990a. b, c, 1992). the effects of salinity and temperature on the rates of oxygen consumption of crustacean species in general have been well documented (kinne 1970, 1971: ivleva 1980; vernberg 1983). similarly, the effects of salinity and temperature on the rates of ammonia excretion have been presented for several crustacean species (need ham 1957: haberfield et al. 1975; mangum et al. 1976; spaargaren et al. 1982; claybrook 1983; quarmby 1985; taylor et al. 1987). some authors have further been focusing on the influence of environmental parameters on the relationship between consumed oxygen and excreted nitrogen (atomic o : n ratio), to obtain an indication of the kind of substrate oxidised by the animals (mayzaud & conover 1988 for ref.). a substrate of only proteins should give a minimum value of 7 (mayzaud 1973). with equivalent weights of proteins and lipids a ratio of 24 is obtained and if lipids and carbohydrates are metabolised, the ratio would approach infinity (conover & corner 1968). our estimates of the 0 : n ratio were used to clarify the nature of the metabolic substrates oxidised in order to meet the energetic require ments during salinity and temperature stress. studies of similar adaptation mechanisms of antarctic under-ice crustaceans (aarset 1988; aarset & torres 1989) as well as arctic intertidal amphipods (aarset & zachariassen 1988) have been included in the pro mare programme to compare the physiological mechanisms involved in the adaptation of amphipods to the under-ice habitat of the barents sea. osmotic regulation arctic sympagic amphipod species appear to be euryhaline organisms (aarset & aunaas 1987a). the adaptation of such animals to changes in seawater salinity is based on two different types of physiological mechanisms: the anisosmotic regulation of inorganic ions between blood and the external medium, and the intracellular isos motic regulation, or cell volume regulation of free amino acids (gilles 1979; gilles & pequeux 1983; clarke 1985). lnorganic ions in the arctic, g . wilkitzkii and 0. glacialis occur on the undersurface and in interstices of the sea ice where they might be exposed to low salinity seawater during sea-ice melting. in such an environment, the sympagic amphipods would face the problem of diffuse loss of solutes and osmotic influx of water. to cope with these problems, the animals may lower their body fluid concentra tions, thus reducing diffusion gradients and/or t h e ion-water permeabilities of the body surfaces, as well as eliminating water through the pro duction of urine (potts 1955; shaw & sutcliff 1961; werntz 1963; lockwood et al 1973; kirsch ner 1979; mantel & farmer 1983). the sympagic amphipod species g. wilkitzkii and 0. glacialis appeared as hyperosmotic regu lators (fig. 1 a), both displaying extracellular regulation of haemolymph concentrations of sodium and chloride (fig. 1b and c ) (aarset & aunaas 1987a). the haemolymph concentration of the poorer regulator g. wilkitzkii was nearly parallel with the isosmotic line in media below a salinity of about 17 ppt (fig. 1a). this response might be of adaptive value for marine organisms inhabiting water which is brackish, due to the reduction in the ionic concentration gradients (potts 1955) (fig. 1b and c). the amphipod 0. glacialis maintained a nearly constant internal fig. 1. haernolyrnph osmolality (a), sodium concentrations (b) and chloride concentrations (c) in the haemolymph of gammarus wilkitzkii (-c-), onisimus glacialis (6) and parathemisto libellula (-el-) acclimated for 24 hours to various salinities. the data are given as mean f sd with number of animals indicated above each point. the solid lines show the isosmotic ( a ) or iso-ionic conditions ( b , c). (aarset & aunaas 1987a). 600 r" 500 e y u 400 ecophysiology of under-ice fauna 311 1 i 1000 e 0" f 800 e o" 600 400 500 z i 400 e 300 concentration of sodium and chloride over a wide range of external salinities (fig. 1b and c), and thus appeared t o be a very efficient osmotic regu lator (fig. 1a). the amphipod p . f i b e f f u f u was a stenohaline osmoconformer with haemolymph isosmotic to the ambient seawater over t h e tolerated salinity range (fig. 1a). t h e observed lack of a sodium and chloride regulation of the haemolymph (fig. 1b and c) is characteristic of osmoconformers (gilles 1979). being an osmoconformer with a relatively low tolerance t o salinity variations, this species is forced t o live in a rather constant environment. t h e species c . wilkitzkii and 0. 312 a . v . aarsef glacialis thus have a larger capacity to adapt to an under-ice environment w i t h salinity variations than p . libellula. the antarctic sympagic amphipod e. ant arcticus and the first juvenile stage of the krill e . supherba appeared as osmoconformers with a low salinity tolerance (aarset 1988), indicating that these antarctic species are not as euryhaline as the arctic species. this might be associated with differences i n the melt progression of the two polar regions with the most significant input of meltwater to the sea surface i n the arctic, creating larger fluctuations in water salinity (gordon 1981; maykut 1985). the physiological response of the antarctic species is thus similar to pelagic crus taceans, while the arctic sympagic fauna behave more as benthic intertidal species (werntz 1963; kinne 1970; dorgelo 1977; aarset & zach ariassen 1988). free amino acids a decrease in the concentration of faa (free amino acids) versus low salinity exposure was documented for the sympagic amphipods g. wil kitzkii and 0. glacialis and has been observed for other crustacean species (florkin & schoffeniels 1969; schoffeniels 1976; gilles 1979; gilles & pequeux 1983; clarke 1985). the adjustment of the intracellular faa seem to be related to inter action of inorganic ions and enzyme activity in such a way that at low salinities the balance of amino acid synthesis and degradation favour a decline in the faa pool. this is reduced by release of amino acids from t h e tissues. a rather high tissue/haemolymph faa ratio in crus taceans reflects the importance of the amino acids in addition to the inorganic ions as intracellular osmotic effectors (gilles 1979; gillles & pequeux 1983; clarke 1985). in the amphipod g . wilkitzkii. a 50% reduction i n the total concentration of free amino acids (tfaa) present at 35% occurred during exposure to 5% salinity (aarset et al. unpubl. data) (fig 2 ) . the decrease in tfaa corresponds to a decline in haemolymph osmolality and inor ganic ions concentrations (aarset & aunaas 1987a). indicating an osmotic response of the amphipod cells. a reduction in the total con centration of essential amino acids (eaa) was also present due mainly to the changes in the concentration of arginine (figs. 2 and 3 ) . arginine is an important component of the phosphagen m m el 0 1 0 2 0 30 40 salinity (o/oo) fig. 2 . concentrations (pmoles/g fresh weight) of total free amino acids (tfaa) and total essential amino acids ( e a a ) in gomrnorus w i l k i t r k i i acclimated for 24 hours to various salini ties. the data are given as mean ? s e (aarset et al. unpubl. data). phosphoarginine in the crustacean muscle and appears sometimes in rather high concentrations (gilles 1979; claybrook 1983). the nonessential amino acids in g. wilkitzkii accounted for more than 80% of the tfaa reduction and do so in most crustaceans (clay brook 1983; aarset et al. unpubl. data). of these glycine, alanine and proline appeared to be the most important osmolytes as well as taurine (fig. 3). taurine is an end product of sulfur amino acid metabolism and like the free amino acids concentrated intracellularly (allen & garrett 1971; huxtable & barbeau 1976; gilles 1979). in g. wilkitzkii. taurine was a most significant osmololyte i n the salinity range of 35 to 15%0. however, dalla via (1986) and mecoid et al. (1984) both demonstrated a minor contribution of taurine as osmoeffector during hyposmotic stress of the shrimp p . japonicus and p . vannamei, respectively. taurine appears therefore not to have the same role as osmotic effector in all crustacean species, and this role can be different i n the same species depending on the salinity in the range tolerated as has been observed for g. wilkitzkii at 5% (fig. 3). the high glycine and alanine concentrations in ecophysiology of under-ice fauna 313 2 8 16. 12. 8 4 3 c (1 -l m e" fig. 3. concentrations (pmole/ g fresh weight) of taurine. glycine. alanine and arginine in gammarus witkirzkii acclimated for 24 hours to various salinities. the data are given as mean 2 se with number of animals indicated (aarset et al. unpubl. data). 8 4 q l y c i n e 4 " e i e 2 e 38 4 0 c. wilkitzkii decreased respectively 70, and 50% at a salinity decline from 35 to 5%0 (aarset et al. unpubl. data) (fig. 3). as loss of amino acids to the sea does not seem to be the main route in crustaceans, the observed reduction could be a result of amino acid catabolism (claybrook 1983). cold tolerance brine exposure ectothermic polar invertebrates and fishes have body temperatures corresponding to the ambient temperature. if the ambient temperature drops below the melting point of the body fluids, the animals face the problem of internal ice forma tion. to cope with this, several general strategies have been developed. freezing tolerance is a strategy based on a tolerance t o tissue ice forma tion, while supercooling is a strategy for avoiding freezing, thus allowing the body fluids to be cooled below the equilibrium freezing point with out freezing (for previous reviews of cold tol erance see aarset 1982; murphy 1983; clarke salinity (o/oo) 1983; zachariassen 1985; 1989; storey & storey 1989). polar ecotherms seem to use both these strategies. cold hardiness as sea ice has a sponge-like structure with cavities, brine channels and crevices, amphipods may become trapped within the bulk sea ice as it grows and thus be exposed to low temperatures. in the arctic, however, the sympagic amphipods c. wilkitzkii and 0. glacialis did not tolerate being frozen into the solid sea ice. instead the amphipods were able t o stay away from the advancing ice front during sea ice growth (aarset & aunaas 1987b). the intertidal spitsbergen amphipod garnrnarus oceanicus, however, could survive being frozen into the solid ice at a tem perature of about 6 to -7" c (aarset & zach ariassen 1988). this has also been observed for the eggs of the subarctic plaice p . platessa (aarset & j ~ r g e n s e n 1988). in antarctica, the first juvenile stage of the 314 a . v . aarset krill, e. superba, unlike the amphipod. e . ant arcticus, tolerated being frozen into the solid sea ice at temperatures down to about 4°c (aarset & torres 1989). although both crustaceans are mobile species, the amphipods avoided the grow ing ice front during freezing experiments while the krill did not. the results correlated well with underwater observations made in the weddell sea. during several scuba dives under the polar pack ice, underwater frazil ice formation was observed. while the krill largely disappeared dur ing the freezing episodes, the amphipods lsft the congelation ice. crawled through the frazil ice layer, and took up a position at the interface of the frazil ice crystal and the surrounding seawater (aarset 1988). supercooling, thermal hysteresis factor ( t h f ) and nucleating activity when the arctic sympagic amphipod g. wilkitzkii were cooled in air, the amphipod froze and died at a temperature of about -4°c (table 1) (aarset & aunaas 1987b). a relatively high supercooling point may indicate that some nucleating agents are present in the body fluids of the animals (zachariassen 1980). in freeze sensitive insects, it is well known that gut content may act as an ice nucleator ( s ~ m m e 1982). in g. wilkitzkii, however, there was no observed difference in the supercooling capacity of animals with and without gut contents. tests for extracellular nucleating agents were also negative (table 1). indicating an intracellular nucleation. similarly, the amphipod a. glacilis had supercooling points of about -7"c, and g. oceanicus, associated with landfast ice, about -6.o"c. (aarset & zachariassen 1988). when the antarctic under-ice crustaceans e . ant arcticus and €. superba were cooled in air, they froze and died at temperatures of about -11°c and -9°c respectively (table 1) (aarset & torres 1989). these relatively low supercooling points indicate that no potent nucleators were present in the body fluids of the animals, and that the antarctic under-ice fauna appeared to have a greater supercooling capacity than the arctic species. rakusa-suszczewski & mcwhinnie (1976) studied the supercooling capacity of benthic and pelagic antarctic species supercooled in filtered seawater. the supercooling capacity was in the range of -4°c to -8°c and ice formation started on gill surfaces and appendages of the animals. our experiments with individuals supercooled in filtered seawater yielded similar results (range -3°c to -6°c) (aarset & torres 1989). however, as the individuals can be supercooled to a lower temperature in air, representing internal ice nucleation, it is probable that ice nucleation initi ated in filtered seawater at a higher temperature originates i n the medium. the survival of the under-ice fauna in a supercooled state could de pend on thermal hysteresis agents present in their body fluids. these are proteinaceous compounds which act to stabilise the supercooled state and which have been demonstrated to be present in different categories of supercooled animals (dev ries 1971; zachariassen & husby 1982; denstad et al. 1987). however, several tests for thermal hysteresis agents in both arctic and antarctic crustaceans were all negative (table 1.) (aarset & aunaas 1987b; aarset & zachariassen 1988; aarset & torres 1989). the fact that animals cooled in freezing seawater were injured at a tahle 1 . thermal data ("c) of under-ice organisms. scp = supcrcooling point. f = frcezing point. m = melting point (mcan f_ sd) species n scp f m f-m ~ ~ ~~~ e antarcircus 3a 3b e superba 6a l b g oceanicus l a 4b g w i l k i t z k r r 6a 5 h a glacralls 5d -11.4?0.6 -1.98 z 0.06 1.95 i 0.07 -0.03 2 0 . 0 9 2 . 0 0 2 0.09 -1.96 2 0 . 0 8 -0.04 2 0 . 1 2 1 . i 3 2 0.04 1 . 1 2 t0.03 -0.01 i 0.0s -1.98 2 0 . m 1 . 9 5 f_ 0.09 -0.03 2 0.1 i 9 . 0 % 1.6 6 . 3 2 0 . 3 3 . 8 2 0.8 -7.8 5 1.7 a = intact animals. b = hdemolymph (data from aarsel & torres 19x9. aarsel & zachariassen 1988. aarset & aunaas 1987b) fig. 4. haemolymph osmolality ( a ) , sodium concentrations (b) and chloride concentrations (c) in the haemolymph of gammorus w i k i r z k i i (*) acclimated for 24 hours to various salinities. the data are given as mean * sd with number of animals indicated above each point. the solid lines show the isosmotic ( a ) or iso-ionic conditions (b, c ) . (aarset & aunaas 1987b). 1800 1600 1400 1200 1000 800 700 6 00 500 9 0 0 800 700 6 00 ecophysiology of under-ice fauna 315 30 35 40 45 50 5 5 60 s a l i n i t y ( % o ) brine exposure during sea-ice growth, brine is excluded to the sea and thereby increases the salinity of the under ice environment (maykut 1985). when the arctic higher temperature than animals cooled in air indicates that other mechanisms than spon taneous internal freezing were causing the injur ies. 316 a . v . aarset amphipod g. wilkitzkii was acclimated to high salinity media, the amphipod responded by being an osmoconforming organism in the salinity range of 34 to 60%0 (fig. 4a). the results also indicate a passive relationship between the concentrations of haemolymph and seawater na' and c1(fig. 4b and c) (aarset & aunaas 1987b). an increased concentration of total faa in g. wil kitzkii versus elevated salinities has been observed. this implies that during sea-ice growth, the amphipods in the vicinity of the ice conform to the ambient brine. thus, the animals lower the melting point of their body fluids and thereby reduce the probability of a heterogenous ice nucleation. an increased body fluid osmolality would probably also cause a colligative depression of the supercooling point (zachariassen & ham me1 1976). this adaptation assumes that the cool ing rate of the medium is slow enough t o make a gradual increase in the brine osmolality, pro moting an osmolality adjustment in the hae molymph of the animals. by direct exposure of g. wilkitzkii to a salinity increase from 34 to 46%0, the amphipod become isosmotic in about 3-4 hours, indicating a good possibility of the animals to conform to the brine in due time underneath the arctic sea ice (aarset & aunaas 1987b). by acclimating to high salinity media, the ant arctic under-ice crustaceans e . antarcticus and e . supherba also conformed osmotically to their tolerated salinity range (26 to 45%0) (aarset & torres 1989), which to some extent corresponds to the studies of the antarctic amphipod orch omene plebs (rakusa-suszczewski & mcwhinnie 1976). during sea-ice growth, both the krill and the amphipod were similar to the arctic amphi pods, able to stay in the vicinity of the ice by conforming to the ambient brine and thus low ering the melting point of their body fluid. however, a low temperature seems to promote the salt tolerance for both the krill and the amphi pods, a mechanism which has previously been documented for other crustaceans (kinne 1964). the arctic and the antarctic sympagic fauna thus seem to be rather alike in their strategy towards freezing. metabolic responses versus salinity although the sympagic amphipod species have developed physiological mechanisms to cope with variations in seawater salinity, the environmental osmotic stress could interfere with the metabolism of the organism. changes in seawater salinity affected the metabolic rates of the sympagic amphipods g. wilkitzkii, 0. glacialis and a . gla cialis. this may be of ecological significance for the arctic amphipods. time-course of metabolic responses versus low salinity the time-courses of specific oxygen consumption and nitrogen excretion rates of g. wilkitzkii and 0. glacialis, transferred from 35 to 5%0 seawater, indicated that the amphipod species elevated both rates just after the transfer and kept them high throughout the experimental period (26-72 hours). although an increase in the time-course of the 0 : n ratio in g. wilkitzkii occurred during the first hours of the hyposmotic stress, the ratio was kept rather constant in both species at about 15-20, reflecting lipid/protein catabolism (aarset & aunaas 1990a, b). these results may indicate that the salinity induced metabolic responses of the arctic amphipods is slower than previously demonstrated for estuarine crustacean species (bulnheim 1972; mangum et al. 1976; taylor et al. 1987). metabolic responses versus salinity acclimation acclimation of the sympagic amphipods g. wil kitzkii, 0. glacialis and a . glacialis to low sal inities induced elevated oxygen consumption rates for all species (aarset & aunaas 1990a. b, 1992). for both 0. glacialis and a . glacialis the lowest rate was obtained at a salinity of 35%0 and the hyposomotic stress induced a 2-3 fold increase in the rate (aarset & aunaas 1990b, 1992). how ever, the oxygen consumption rate of g. wilkitzkii was salinity-independent i n the range of 25 to 48%0 (fig. 5a). below a salinity of 15-20%0 g. wilkitzkii was rather sensitive to salinity stress, with a 2-3 times increase i n the oxygen con sumption rate when transferred from 35 to 15%0. this indicates that the amphipods can live in the sea-ice environment in the fully compensated salinity range with minor changes in energy requirements. in an invironment with salinities below 15-20%0, the animals will need higher energy inputs. however, the salinity had little effect on the mean oxygen consumption rates of e . antarcticus and e . superba in their tolerated salinity ranges (aarset & torres 1989). ecophysiology of under-ice fauna 317 fig. 5. the rates of specific oxygen consumption ( a ) , specific ammonia excretion (b) and o : n ratios (c) of gammarus wilkifzkii acclimated for 24 hours to various salinities. the data are given as mean t sd with number of animals indicated above each point (aarset & aunaas 1990a). a 16 1 4 5 12 10 i 0 6 4 2 2 rn 0' i i 10 20 30 4 0 b 3 2 1 4 i 4 i 4 10 20 30 4 0 50 2 0 10 20 30 4 0 salinity (o/oo) an increased ammonia excretion rate in dilute media was documented for the under-ice amphi pods g. wilkitzkii, 0. glacialis and a . glacialis. this has previously been noted in a number of other crustacean species (reginault 1984; taylor et al. 1987; haberfield et al. 1975; spaargaren et al. 1982; harris & andrews 1985; aarset & aunaas 1990a, b , 1992). exposure of g. wil 318 a . v . aarset kitzkii to the 24 hour hyposmotic stress resulted in a substantial increase in ammonia excretion rates in individuals exposed to salinities below 2 5 % ~ (fig. 5b). thus, the excretion rate to some extent seems to correspond with the changes in the oxygen consumption rate. in the salinity range of 2 5 4 8 % ~ . there was a small decrease in excretion rate, indicating that the amphipods were not fully compensating for the salinity vari ations in the media. exposure to salinities below 15-20%0 revealed sensitivity to the salinity stress with a 2-3 times increase in the excretion rate. this observation and the concomitant elevation of the oxygen consumption rates might support an energetically favourable migration of the animals into waters of higher salinities. changes in the energy substrate utilisation as a function of osmotic stress has been observed in some crustaceans (tendengran et al. 1988; stern et al. 1984); however. a rather constant 0: n ratio of about 15-20 has been documented for the sympagic amphipods 0. glacialis and a . glacialis (aarset & aunaas 1990b. 1992). in g. wil kitzkii the pooled 0 : n ratio for 24 hours osmotic stress varied from 21 at hyposmotic to 37 at hyp erosmotic stress (fig. 5 c ) ; however, individual variations i n the ratios displayed no significant differences. ikeda & bruce (1986) pooled the data for 12 antarctic zooplankton species and obtained an 0: n ratio of about 14. antarctic krill e . superba ranged from 21 to 50 (hirche 1983). metabolic responses versus osmolality differences haemolyph sodium concentrations in many crustaceans the respiratory rate has been demonstrated to be highest when the osmotic difference between haemolymph and external medium is at a maximum (rao 1985; king 1965; hagermann 1970). the lowest respiratory rate occurred when the osmotic difference between haemolymph and medium was minimal. the observations were supported by the studies of g. wilkitzkii (fig. 6a) and 0. glacialis (aarset & aunaas 1990a, b). these amphipods were osmo regulators at low salinities, maintaining elevated haemolymph concentrations of na' and ci (aarset & aunaas 1987a). the observed increase in the oxygen consumption rates thus seems to indicate increased energy requirement for osmotic regulation at low salinities. however, the energy actually required for osmoand ionic regulation in crustacean species. calculated from thermodynamic considerations, has been claimed to account for only a minor part (1-5%) of the observed increase in the oxygen consumption rate (potts 1955; styczynsaka-jurewicz 1970; spaar garen 1975; dalla via 1987). another reason for the accelerated respiratory rates may be related to the catabolism of free amino acids during cell volume regulation, as the control of the amino acid pool is governed mostly by changes in trans port activity, deamination, and oxidation of the acids to c 0 2 (gilles 1973). mangum et al. (1976) demonstrated that ammonia excretion of the crab callinecfes sapidus was related to the osmotic difference between blood and water. these observations were sup ported by the excretion rate of both g . wilkitzkii (fig. 6b) and 0. glacialis (aarset & aunaas 1990a, b). the main site of ammonia transfer in crustaceans appears to be the gill epithelium (evans & cameron 1986), where the nhf ion has been proposed to act as a counter ion in the regulation of haemolymph sodium concentrations (weiland & mangum 1975; kirschner 1979; taylor et al. 1987). thus, a minor decrease in haemolymph sodium would coincide with increased ammonium output during hyposmotic stress. in g. wilkitzkii the time-course of the haemolymph sodium concentration might support this observation. in several crustacean species, the rate of ammonia excretion may be reduced during long term exposure to hyperosmotic stress (needham 1957; mangum et al. 1976). in g. wilkitzkii there was a decrease in the excretion rate of individuals exposed to salinities from 25 to 4 8 % ~ indicating a metabolic requirement of the nhz ion at higher salinities. armstrong et al. (1981) suggested a reversal of the na+/nh; exchange mechanism in the prawn macrobrancium rosenbergii, allowing the animals t o hyporegulate in con centrated media. however, no ability to hypo regulate has yet been demonstrated in g. wilkitzkii (aarset & aunaas 1987b). hypo regulation would raise the melting point of the amphipod haemolymph, and under such cir cumstances ice nucleation would be likely to occur at low temperatures. metabolic responses versus temperature crustaceans which have adapted to the low tem peratures of the antractic oceans seem to be ecophysiology of under-ice fauna 3 19 60 5 0 40 r 30 0 20 l o a fig. 6 . the rates of specific oxygen consumption ( a ) , specific ammonia excretion ( b ) and o:n ratios (c) of gammarus wilkitzkii as a function of the osmotic difference between the heamolymph and medium osmolality. the simple regressions are indicated by solid lines (aarset & aunaas 1990a). c 8 8 8 8 8 m 8 8 8 8 8 8 y = 1.1 + 0 . 0 1 5 9 ~ r = 0.80 a 20 p < 0.001 15 8 ' 8 10 8 8 0 1 100 200 300 400 y = 0.3 + 0.0035~ r = 0.87 b 1 p c 0.001 8 8 i 1 100 200 300 400 8 8 osmolality haernolymph-medium (mosm) 320 a . v . aarsef sensitive to elevated ambient temperatures (rakusa-suszczewski 1980, 1982; rakusa-susz czewski & klekowksi 1973). however, scho lander et al. (1953) and percy (1975) indicated that most of the canadian arctic crustaceans they studied survived a temperature exposure of about 18°c. in our studies of g . wilkitzkii, 0. glacialis and a . glacialis, short term temperature exposures from -1" t o 10°c were not lethal to the under-ice amphipods, although the maximal annual variation in temperature of the surface waters of the arctic barents sea is about 3 4 ° c . as the crustaceans are unable to control their body temperature, their metabolic rates should vary with changes in ambient temperatures. the general response to increasing temperature is an increased metabolic rate, although several crus tacean species appear to be thermally insensitive (low qlo values) over wide temperature ranges (prosser 1973; vernberg 1983). oxygen consumption percy (1975) reported that the oxygen con sumption rate of the winter acclimated individuals of the benthic amphipod onisimus affinis were relatively temperature-insensitive between 0" and 8°c with a q l o of 1.36. however, above 8" the rate increased rapidly with temperature as indi cated by a qlo of 2.4 between 8" and 15°c. similar results have been demonstrated for the arctic copepod calanus glacialis (tande 1988) and the antarctic krill euphausia superba (mcwhinnie 1964). the effect of elevated temperatures on the metabolic rates of the arctic under-ice amphi pods g . wilkitzkii, 0. glacialis and a . 'glacialis revealed an overall increase-response for all species (aarset & aunaas 1990c, d). although the rate of a . glacialis appeared to be independent at temperatures between 0" and 5"c, with a rather low qlo value, the rate increased significantly as the temperature increased further from 5" to 10°c (fig. 7a). the first response may thus indicate a conservation of energy at low temperatures. both g . wilkitzkii and 0. glacialis exhibited "normal" qlo values of 3.4 and 3.6, respectively, in the temperature range 0" to 10°c. in the range from 0" to 5°c. which is approximately the range these amphipods generally would experience in the arctic, both species displayed rather high qlo values, with the most pronounced increased by 0. glacialis (aarset & aunaas 1990b). high qlo values have been documented for several polar species as an indication of sensitivity to tem perature changes (klekowski et al. 1973). however, scholander et al. (1953) discussed the problems by using qlo as an indicator of adap tation to the environment. they concluded that physiological adaptation of poikilotherms to cold was reflected in the lateral displacement of the metabolism temperature curve. wohlschlag (1960) supported this theory, but arguments against the concept of metabolic cold adaptation have also been presented (clarke 1980, 1983; maxwell & ralph 1985). however, the metab olism temperature curve may vary according to season, starvation, sex, and activity of the animals (vernberg 1983; clarke 1980), making com parative data difficult to interpret. ammonia excretion the rate of ammonia excretion represents a rate at which metabolic systems are digesting, assimi lating and processing nitrogen substances. an increase in the excretion rate with increasing tem peratures therefore suggests an increase in the digestion and assimilation efficiencies at higher temperatures. several crustacean species, such as the spot prawn pandalus platyceros and the antarctic isopod glyptonotus antarcticus (white 1975), do increase the excretion rate with tem perature. however, excretion rates of copepodite stage v as well as adult females of the arctic copepode calanus glacialis were temperature independent in the range of -1.7" to 1°c (tande 1988). the effect of elevated temperature on the excretion rate of the under-ice amphipod a . gla cialis revealed a significant increase in the rate at both 0", 5" and 10°c with an overall qlo of 1.8 (fig. 7b). the results reveal a significant increase in the nitrogen excretion rates for both g . wil kitzkii and 0. glacialis by an elevation of tem perature from 0" to l o t , with an overall qlo of 1.9 and2.3 respectively (aarset & aunaas 1 9 9 0 ~ ) . in the temperature range from 0" to 5°c the most pronounced effect, as for the oxygen consumption rate, occurred in 0. glacialis. thus, the ammonia excretion rates indicated an increased n-loss to the environment during the high temperature exposure. however, as the arctic poikilotherms usually are subjected to only minor variations in sea surface temperature, the observed n-loss to the arctic polar ocean would be significantly lower. ecophysiology of under-ice fauna 321 1,50 1,45 1,40 1 3 5 1,30 1,25 1,20 1,15 . d . a y-0.033~+0.633 1 r = 0 . 8 2 8 p = 0 . 0 0 0 1 c y . 0 . 0 1 8 x + 1.209 0 r = 0.847 p ' 0 . 0 0 0 1 i i i i i i i a y 0 . 0 3 3 x + 0.633 . 1 i = 0 . 8 2 8 p = 0 . 0 0 0 1 0,4 ' i i i i i i 0 2 4 6 8 1 0 fig. 7. the rates of log specific oxygen consumption 2 (a), specific ammonia excretion ( 8 ) and o : n ratios 0 (c) of apherwa glacialis at a salinity of 35 ppt. after an acute exposure to temperatures of 0". 5" and 10°c. the simple regressions are represented by solid lines enclosed by 95% confidence limits. each point represents one animal (aarset & aunaas 1992). .. yo . d 2 7 x + 0 . 0 8 3 r = o . b i s p = 0 . 0 0 0 1 . -0,05 ' i i 0 i i i 0 2 4 6 8 10 temperature ("c) (1974) demonstrated an 0 : n ratio of warm water species to be lower than cold water species. the copepod acartia clausi and the krill meganycfi phanes n o r w i c a exhibited opposite response to increasing temperature (conover & mayzaud 1976) while white (1975) found a bimodal dis tribution for the antarctic isopod glyptonotus 0: n the 0 : n atomic ratio reflects the overall balance of the amphipod metabolism, related to internal energy requirements and external variables. it seems to be sensitive to the nutritious status of the animals, to the season, and to some extent the temperature (mayzaud & conover 1988). k& 322 a . v . aarset antarcticus. the sympagic amphipod apherusa glacialis demonstrated an increase in the 0 : n ratio with temperature elevation (fig. 7 c ) and similar observations have been obtained for g. wilkitzkii and 0. glacialis with overall qlo values of 2.0 and 1.6 respectively (aarset & aunaas 1990~). this indicates a temperature induced change i n the metabolic substrate for all species towards lipids. however, in the temperature range from 0" to 5°c the most pronounced increase occurred in g. wilkitzkii. in conclusion, the oxygen consumption rates for all species seem to be more sensitive to acute temperature exposure than the nitrogen excretion rates, which might represent a general trend in arctic amphi pod metabolism. acknowkdgemenrs this work is part of the pro mare pro gramme and has been financed by the norwegian research council for science and humanities(navf) the author would like to thank k e zachariassen for reading the manuscript references aanct. a. v. 1982: freezing tolerance in intertidal invert ebrates (a review). comp. eiochem. physiol. 73a. 571-580. aarset. a . v. 1988: under-ice fauna from the weddell sea; responses to low temperature and osmotic stress. anrarrric j . us 22, 17g171. aanet, a . v. & aunaas. t . 1987a: osmotic responses to hyposmotic stress in the amphipods gammarus wilkirzkii. onisimus glacialis and pararhemisro libellula from arctic waters. polar biol. 7. 18s.193. aarset, a . v. & aunaas. t. 1987b: physiological adaptations to low temperature and brine exposure in the circumpolar amphipod gammarus wilkirzkii. polar b i o l 8 . 129-133. aarset. a. v . & aunaas. t. 1990a: effects of osmotic stress on oxygen consumption and ammonia excretion of the arctic sympagic amphipod gammarus w i l k r r z k i i . mar. ecol. prog. ser. 58. 217-224. aarset. a . v . & aunaas. t. 1990h: the influence of environ mental salinity on oxygen consumption and ammonia excretion of the under-ice amphipod onisimusglacialis. mar. biol. 107. 9-15. aarset. a . v . & aunaas. t. 19°c: metabolic responses of the sympagic amphipods gammarus w i l k i r z k ~ i and onisimur glacialis to acute temperature variations. mar. biol. 107.433 438. aarset, a . v . 8r aunaas. t. 1992: metabolic responses of acute temperature and osmotic stress of the arctic under-ice amphipod aphericta glacialis. polar 6101. i n press. aarset. a . v . & torres, j . j . 1989: cold resistance and meta bolic responses to salinity variations in thc amphipod eusirus antarcticur and the krill eupausiasuperba. polar eiol. 9.491 497. aarset. a. v. & jsrgensen. l. 1988: cold hardiness of the eggs of the plaice. pleuronecres plaressa polar biol. 9. 95-99. aarset. a. v & zachariasscn. k . e 1988: low temperature tolerance and osmotic regulation of the amphipod gammarus oceanicw from spitsbergen waters. polar res.6, 35-41. allen. j . a . & garrett. m. r. 1971: taurine in marine invcrt ebratcs. ado. mar. biol. 9. 205-253. andreas. e. l . & ackley. s . f. 1982: on the differences in ablation seasons on the arctic and antarctic sea ice. 1. arrnos. sci. 39. 440.47. armstrong. d. a,. strange. k . , crowe, j . . knight, a . & simmons. m. 1981: high salinity acclimation by the prawn macrobrochium rosenbergii: uptake of exogenous ammonia and changes in endogenous nitrogen compounds. biol. bull. mar. b i d l a b . . woo& hole 160, 34%365. bulnheim, h . p. 1972: vergleichende untersuchungen zur atmungsphysiologie euryhaliner gammariden unter beson derer berucksichtigung der salzgehaltsanpassung. helgo lander wiss. meeresunrers. 23. 48s534. carey. a . g . . jr. 1985: marine ice fauna: arctic. pp. 17>190 in homer. r . a . (ed.): sea ice biota. crc press. florida. clarke. a. 1980: a reappraisal of the concept of metabolic cold adaptation in polar marine invertebrates. pp. 77-92 in bonner. w. n. & berry. r . j. (eds.): ecologyin rheanrarcric. academic press, london. clarke. a . 1983: life in cold water: the physiological ecology of polar marine ectotherms. oceanogr. mar. biol. ann. rev. 21. 341-453. clarke. m. e. 198.5: the osmotic role of amino acids: discovery and function. pp. 412423 in gilles. r . & gilles-baillien, m. (eds.): transporr processes, ionoand osmoregulation. springer verlag. berlin. claybrook. d. l. 1983: nitrogen metabolism. pp. 163-213 in mantel, l. h. ( e d . ) the biology of crusracea. inrernal anat omy and physiological regularion. vol 5 . academic press, new york. cross, w. 1982: under ice biota at the pond indlet ice edge and in adjacent fast ice areas during spring. arcric35, 1>27. conover. r. j . & corner. e. d. s. 1968: respiration and nitrogen excretion by some marine zooplankton in relation to their life cycles. j , mar. biol. ass. u.k. 48. 49-75. conover. r. j . & mayzaud, p. 1976: respiration and nitrogen excretion neritic zooplankton in relation to potential food supply. pp. 151-163 in persoone, g. & jaspers, e. (cd.): proc. 10th europ. mar. biol. symp. osrend. belgium, vol2. univers. press, wetteren. cox. g . f. n . & weeks. w. f. 1974: salinity variations in sea ice. 1. glaciol. 67. 109-120. dalla via. g . j. 1986: salinity responses of the juvenile penaeid shrimp penaeusjaponicus. free amino acids. aquaculture 55, 307-316. dalla via. g. j . 1987: effects of salinity and temperature on oxygen consumption in a freshwater population of pala emoneres anrennarius (crustacea. decapoda). comp. biochem. phvsiol. 8 8 a . 299-305. denstad. j . p.. aunaas. t . . bsrseth, j . f.. aarset. a . v. & zachariassen, k. e. 1987: thermal hyteresis antifreeze agents i n fishes from spitzbergen waters. polar res. 5 . 171-174. devries. a. l. 1971: glycoproteins as biological antifrecze agents in the antarctic fishes. science 172. 1152-1155. dorgelo. j . 1977: comparative ecophysiology of gammarids (crustacea: amphipoda) from marine. brachishand fresh water habitats exposed to the influence of salinity-tcm perature combinations. i v . blood serum regulation. neth. 1. sea. res. 11. 184199. eide. l . & martin, s. 1975: the formation of brine drainage features in young sea ice. j. glaciol. 14. 137-154. ecophysiology of under-ice fauna 323 evans, d. h. &cameron. j. n. 1986: gill arnmoniatransport. 1. exp. 2001. 239. 17-23. florkin, m. & schoffeniels, e. 1969: molecular approaches to ecology. academic press, ny. gilles, r. 1973: oxygen consumption as related to the amino acid metabolism during osmoregulation in the blue crab cal linectes sapidus. neth. j . sea res. 7, 2 w 2 0 7 . gilles, r . 1979: mechanisms of osmoregulation in animals. wiley & chichester uk. gilles, r . & pequeux, a. 1983: interactions of chemical and osmotic regulation with the environment. pp. 109-177 in vernberg, j. f. & vernberg, w. b. (eds.): the biology of crustacea, vol. 8, academic press, ny. gordon, a. l. 1981: seasonality of southern ocean sea ice. j. geophys. res. 86, 4192-4197. green, j. m. & steele. p. 1975: observation of marine life beneath sea ice, resolute bay, nwt. proc. cicum conf nothern e c o l 2 , 77. gulliksen, b. 1984: under-ice fauna from svalbard waters. sarsia 69. 17-23. gulliksen, b . & lonne, 0. j . 1989: distribution, abundance and ecological importance of marine sympagic fauna in the arctic. rapp. p.-o. rcun. cons. int. explor. mer 188, 133 138. haberfield, e. c.. haas, l. w. & hammen, c. s. 1975: early ammonia release by a polychaete nereis uirens and a crab carcinus maenas in diluted sea water. comp. biochem. phys iol. 5 2 , 501-503. hagerman, l. 1970: the oxygen consumption of crmgon oul garis (fabricius) (crustacea, natantia) in relation to salinity. ophelia 7, 283-292. harris, r. r. & andrews, m. b. 1985: total nps pool and ammonia net efflux rate changes in carcinus maenas during acclimation to low environmental salinity. cornp. biochem. physiol. 82a, 301-308. hirche, h. j. 1983: excretion and respiration of the antarctic krill euphausia superba. polar. biol. i , 205-209. horner, r. a. (ed.) 1985: sea ice biota. crc press, boca raton, florida. 215 pp. huxtable, r. & barbeau. a . 1976: taurine. raven press, ny. 398 pp. ikeda, t. & bruce, b. 1986: metabolic activity and elemental composition of krill and other zooplankton from prydz bay. antarctica, during early summer (november-december). mar. biol. 92, 545-555. ikeda, t. 1974: nutritional ecology of marine zooplankton. mem. fac. fish. hokkaido uniu. 22, 1-97. ivleva, i. v. 1980: the dependence of crustacean respiration rate on body mass and habitat temperature. lnt. reo. ges. hydrobiol. 65, 1-47. king. e. n. 1965: the oxygen consumption of intact crabs and excised gills as a function of decreased salinity. comp. biochem. physiol. 15, 93-102. kirschner, l. b. 1979: control of the extracellular fluid osmo larity, control mechanisms in crustaceans and fishes. pp. 157 222 in gilles, r. (ed.): mechanisms o f osmoregulation in animals. wiley. new york. kinne. 0. 1964: the effects of temperature and salinity on marine and brackish water animals. 2. salinity and tem perature-salinity combinations. oceanogr. mar. biol. ann. reo. 2 , 281-339. kinne, 0 . 1970: temperature. pp. 407-512 in kinne. 0. (ed.): marine ecology. environmental factors, vol i . wiley-lnter science, london. kinne. 0.1971: salinity. pp. 821-996 in kinne. 0. (ed.): marine ecology. environmental factors, ool 1, wiley-interscience, london. klekowski. r. z., opalinski. k. w. & rakusa-suszczewski. s . 1973: respiration of antarctic amphipoda paramoera walkeri stebbing during the winter season. pol. arch. hydrobiol. 20. 301-308. lake, r. a. & lewis, e. l. 1970: salt rejection by sea ice during growth. j . geophys. res. 75, 58s590. lockwood, a . p. m., inmann. c. b. e. & courtney, t. h . 1973: the influence of environmental salinity on the water fluxes of the amphipod crustacean gammarus duebeni. j . exp. biol. 58, 137-148. malmgren, f. 1927: on the properties of sea-ice. pp. 1-67 in sverdrup. h. v. (ed.): the norwegian north polar expedition with the "maud" 1918-1925 scientific results, vol. i , no. 5 . mangum, c. p., silverthorn, s. u., harris, j. l.. towle. d. w. & krall, a . r. 1976: the relationship between blood ph, ammonia excretion and adaptation t o low salinity in the blue crab callinectes sapidus. j . exp. 2001. 195, 129-136. mantel. l. h. & farmer, l. l. 1983: osmotic and ionic regu lation. pp. 53-161 in mantel, l. l. (ed.): the biology of crustacea. lnternal anatomy and physiological regulation, vol. 5 . academic press, ny. maykut, g. a. 1985: the ice environment. pp. 21-82 in horner, r . a . (ed.): sea ice biota. c r c press. boca raton, florida. mayzaud. p. 1973: respiration and nitrogen excretion of zooplankton. i1 studies of metabolic characteristics of star ved animals. mar. biol. 21, 19-28. mayzaud. p. & conover, r. j. 1988: o : n atomic ratio as a tool t o describe zooplankton metabolism. mar. ecol. prog. ser. 45, 28%302. maxwell, j . g . h. & ralph, r . 1985: non-cold adapted metab olism in the decapod chorismus antarcticur and other sub antarctic marine crustacean. pp. 397-406 in siegfried, w. r., condy, p. r. & laws. r. m. (eds.): anfarcfic nutrient cycles and food webs. springer verlag, berlin. mccoid, v., miget. r. & finne. g . 1984: effect of environ mental salinity of the free amino acid composition and con centration in penaeid shrimp. j . food sci. 49, 327-300. mcwhinnie, m. a . 1964: temperature responses and tissue respiration in antarctic crustacean with particular reference to krill euphausia superba. ant. res. ser. 1 , 63-72. murphy, d . j . 1983: freezing resistance in intertidal invert ebrates. ann. reu. physiol. 45, 289-299. nansen, f. 1906: protozoa from the ice-floes of the north polar sea. pp. 1-22 in nansen, f. (ed.): the norwegian north polar expedition 1893-1896 scientific results, vol. 5 . no. 16. needham, a. e. 1957: factors effecting nitrogen excretion in carcinus maenas (pennant). physiologia romp. oecol. 4 , 209-239. newbury, t. k. 1983: under landfast ice. arctic 36, 328-340. niedrauer, t . m. & martin, s. 1979: an experimental study of brine drainage and convection in young seas ice. j . geophys. res. 84. 11761186. percy, j . a . 1975: ecological physiology of arctic marine invert ebrates. temperature and salinity relationships of the amphi pod onisimus afinis h. j . hansen. j . exp. mar. biol. ecol. 20. 9p117. potts, w. t. w. 1955: the energetics of osmotic regulation in brackish and fresh-water animals. j. exp. biol. 3 1 , 61b630. 324 a , v . aarset prosser. c. l . 1973: comparative animal physiology. w. b. saunders. philadelphia. quarmby. l . m. 1985: the influence of temperature and salinity on the nitrogen excretion of the spot prawn. pandalus pla ryceros brandt. j . exp. mar. biol. ecol. 87. 229-239. rao. k. p. 1958: oxygen consumption a, a function of size and salinity in metapenae us monoceros fab. from marine and brackish-water environments. j. exp. biol. 35. 307-313. rakusa-suszczewskl. s. 1980: hypostenothermic organisms. pol. polar res. 4. 231-241. rakusa-suszczewski, s. 1982: the biology and metabolism of orchomene plebs (hurley 1965) (amphipoda: gammaridea) from mcmurdo sound. ross sea, antarctica. polar biol. i . 47-54. rakusa-suszczewski, s. & klekowski. r . 2. 1973: biology and respiration of the antarctic amphipoda (paramoera walkeri stebbing) in the summer. pol. arch. hydrobiol. 2 0 . 4 7 w 8 . rakusa-suszczewski. s. & mcwhinnie m. a. 1976: resistance to freezing by antarctic fauna: supercooling and osmo regulation. comp. biochem. physiol. 5 4 a . 291-30. reginault, m. 1984: salinity-induced changes in ammonia excretion rate of the shrimp crangon crangon over a winter tidal cycle. mar. ecol. prog. ser. 20, 11%125. schoffeniels, e. 1976: adaptation with respect to salinity. bio chem. soc. symp. 41. 179-204. scholander. p. f.. flagg. w.. walters. v. & irving. l. 1953: climatic adaptation in arctic and tropical poikilotherms. physiol. 2001. 26. 67-92. shaw. j. & sutcliff, d. w. 1%1: studies on sodium balance in cammarus duebeni. lil jeborg and g. pulex pulex ( l . ) j . exp. biol. 38. 1-15. sbmme, l. 1982: supercooling and winter survival of tcrrestrial arthropods. comp. biochem. physiol. 7 3 a . 51%543. spaargaren. d. h. 1975: energy relations in the ion regulation in three crustacean species. comp. btochem. physiol. 5 1 , 543-548. spaargaren. d. h . , richard. p . & ceccaldi. h . i . 1982: excretion of nitrogenous products by penaeus japonicus bate i n relation to environmental osmotic conditions. comp. bio chem. physiol. 7 2 a . 673-678. stern. s.. borut, a. & cohen, d. 1984: the effect of salinity and ion composition on oxygen consumption and nitrogen excretion of macrobrachtum rosenbergii. comp. biochem. storey, k. b. & storey. j . m. 1989: freezing tolerance and freezing avoidance in ectotherms. pp. 51-82 in wang, l. c. h. (cd.): advances in comparatiue and enuironmental physiology. vol 4 . springer verlag. berlin. phy~iol. 79a. 271-274 styczynska-jurcwicz. e. 1970: bioenergetics of osmoregulation in aquatic animals. pol. arc. hydrobiol. 1. 295-302. tande. k. 1988: the effect of temperature on metabolic rates of different life stages of calanus glacialis in the barents sea. polar biol. 8. 457-461. taylor. a . c . , spicer. j . 1. & preston, t. 1987: the relationship between osmoregulation and nitrogen metabolism in the intertidal prawn. palemon elegans (rathke). comp. biochem. physiol. 88a. 291-298. tedengren. m.. arner, m. & kautsky, n. 1988: ecophysiology and stress response of marine and brackish water gammarus species (crustacea. amphipoda) to changes in salinity and exposure to cadmium and diesel-oil. mar. ecol. prog. ser. 4 7 . 107-116. vernberg, f. j. 1983: respiratory adaptions. pp. 1-42 in bliss, e. d. (ed.): the biology of crusracea. environmental adap tiom, v o l 8 . academic press. new york. wakatsuchi. m. & ono. n. 1983: measurements of salinity of brine excluded from growing sea ice. j . geophys. res. 88. 294-295. weeks, w. f. 1968: understanding the variationsofthe physical properties of sea ice. symp. anrarcf. ocean, chile, scotf pol. res. lmt., 173-190. weiland. a . l. & mangum. c . p. 1975: the influence of environmental salinity on hemocyanin function in the blue crab, callinectes sapidus. j. exp. zool. 193. 265-274. werntz, h . 0. 1963: osmotic regulation in marine and fresh water gammaridc (amphipoda). biol. bull. 124, 225-230. white. m. g . 1975: oxygen consumption and nitrogen excretion by the gigant antarctic isopod glypfonotus anr arcricus eights in relation to cold-adapted metabolism in marine polar poikilotherms. proc. 9 f h europ. mar. biol. symp.. aberdeen, 707-724. wohlschlag. d. e . 1960: metabolism of an antarctic fish and the phenomenon of cold adaptation. ecology 41, 287-292. zachariassen. k. e. 1980: the role of polyols and nucleating agents in cold-hardy beetles. 1. comp. physiol. 140,227-234. zachariassen. k. e . 1985: physiology of cold tolerance in insects. physiol. rev. 65. 7 w 8 3 2 . zachariassen, k. e. 1989: thermal adaptation to polar environ ments. pp. 23-34 in mercer. j . (ed.): thermal physiology. excerpta medica, oxford. zachariassen. k. e. & hammel. h. t. 1976: nucleating agents in the haemolymph of insects tolerant to freezing. nature 262. 285-287. zachariassen. k. e . & husby. j . a . 1982: antifreeze effectsof thermal hysteresis agents protects highly supercooled insects. nature 298, 865-867. no job name environmental change as a threat to the pilot whale hunt in the faroe islandspor_168 430..438 russell fielding department of geography and anthropology, louisiana state university, 227 howe-russell-kniffen geosciences complex, baton rouge, la 70803, usa. e-mail rfield2@lsu.edu abstract the faroese pilot whale hunt—the grindadráp—has provided meat and blubber for human consumption since at least the late 16th century. this paper briefly discusses the history of the grindadráp in the context of its culture and broader human–environmental interactions. it then describes threats to the continuance of the grindadráp, including the possibility of over-extraction through poor management, international protests and boycotts, and the current issue of marine pollutants found in the tissues of the whales. next, it examines the outcomes, or anticipated outcomes, of each of these threats. the coordination of science and policy has arguably ensured a sustainable take level, whereas the redirection of many protest efforts to other, more commercialized whaling operations has reduced international pressure on the faroese to give up whaling. however, the issue of environmental pollutants remains, and has become the leading threat to the grindadráp. it concludes with a look to the future and at what changes the faroese would have to make in their current food and cultural systems were the grindadráp to cease, and what the environmental, economic and cultural effects of those changes might be. the major options examined are: increasing the importation of foodstuffs, increasing local food production and redirecting part of the fisheries’ catch from exports to the local market. each option carries its own environmental, economic and cultural impact. a careful combination of the three will most likely prove to be best, if indeed the grindadráp is to be reduced or abandoned. keywords environment; faroe islands; food production; islands; mercury; whaling. correspondence russell fielding, department of geography and anthropology, louisiana state university, 227 howe-russell-kniffen geosciences complex, baton rouge, la 70803, usa. e-mail: rfield2@lsu.edu doi:10.1111/j.1751-8369.2010.00168.x the meat and blubber of the long-finned pilot whale (globicephala melas) have long been an important part of the diet in the faroe islands, a semi-independent archipelagic nation in the north atlantic (fig. 1). several times each year, large family groups—known as schools or pods—of these relatively small, toothed whales are driven ashore in a collective effort by dozens of faroese boats, and are killed with small hand-held knives when the pod has become beached on the shore or stranded in shallow water. the quick exsanguination of dozens of whales turns the harbour waters red: a shocking sight for the uninitiated observer. after the kill, local authorities distribute the meat and blubber free of charge among the hunt’s participants, and then among the residents of the district in which the landing took place. this activity—known in faroese as the grindadráp—is governed by strict regulations under faroese law and is not subject to the jurisdiction of the international whaling commission (iwc). the iwc regulates the take of the “great whales” (i.e., all baleen whales and the sperm whale [physeter macrocephalus]), but does not regulate the take of “small cetaceans” such as pilot whales. iwc member countries regulate their own take or nontake of small cetaceans. the faroe islands are an autonomous province of denmark, and were granted home rule in 1948. since that time, the topic of full independence has been discussed within faroese public and political discourse (ackrén 2006). denmark supplies the faroes with an annual subsidy, police and military forces, and handles some international representation, though the faroese home rule government handles most domestic affairs, including regulation of the grindadráp, and an increasing number of foreign affairs. the danish delegation to the polar research 29 2010 430–438 © 2010 the author, journal compilation © 2010 blackwell publishing ltd430 mailto:rfield2@lsu.edu mailto:rfield2@lsu.edu iwc is made up of representatives from denmark and the faroes, as well as representatives from greenland, which has also been granted home rule by the danish government. challenges grindadráp have occurred throughout the norse history of the faroes, with written descriptions from as early as 1632 (sanderson 1992), locally-kept statistical records from 1584 (van ginkel 2005), and archaeological evidence for the presence of pilot whales in the early faroese diet dating to the “viking age” (sanderson 1992), which is generally defined in the faroes as lasting from ad 800 to ad 1035 (edwards 2005). throughout the history of the faroe islands, various cultural and environmental forces have challenged the continuation of the grindadráp. of these, three have dominated academic discourse about the persistence of whaling in modern societies in recent decades. one is over-extraction, that is, the possibility that whaling takes place at an unsustainable level, exhausting the stocks of pilot whales or decreasing their genetic diversity to the point that they are no longer able to maintain a viable population. in this scenario, faroese whaling would cease simply because there would not be enough whales to make the activity worthwhile, or the activity would become illegal (either by faroese law or international treaty) before the stocks got too low in order to facilitate a revival of the pilot whale population. over-extraction in the faroes would echo the situation that newfoundland experienced with its own pilot whaling industry in the mid-20th century (dickinson & sanger 2005). another force is protest and boycott, in the form of anti-whaling organizations successfully lobbying other nations, corporations or individuals to stop trade with the faroes unless they cease whaling activities, thus decreasing the market for faroese fish, which is by far the main export of the islands. in this scenario, the faroese would voluntarily give up whaling (a non-commercial activity) in order to save their fisheries (their leading source of income) from international boycott. the peak of the protest against faroese whaling occurred during the 1980s and 1990s, and was well documented by sanderson (1990, 1994) who was a key player in the discourse, owing to her role with the faroese office of the prime minister, which required her to provide official answers to many of the protest letters written to the faroese government. a third challenge to whaling in the faroes is pollution in the form of methyl-mercury (mehg) and other toxins that accumulate in the tissues of the pilot whales and cause adverse health effects in consumers. this threat is the subject of ongoing research by faroese scientists and researchers from abroad. leading the research efforts are two medical doctors, philippe grandjean of the harvard school of public health and the university of southern denmark’s institute of public health, and pál weihe, chief physician in the department of occupational and public health in the faroese hospital system. if this threat were to lead to the termination of whaling in the faroe islands it would be the result of a government ruling or recommendation in the interest of public health, and would most likely originate from the office of dr weihe. in recent decades, each of these scenarios has taken its turn as the leading threat to the continuance of the grindadráp, at least in the realm of public perception. i will discuss below each threat as well as its likely outcome. over-extraction the faroese take on average 900–1000 pilot whales each year, although there is much variance from this mean. in some years—notably around wwii—many more whales than average were taken; in other years—most recently, 2008—no whales were taken at all (statistics faroe islands 2008). over-extraction has the potential to become a threat to any wild animal harvest. without good management to keep technological advances and human population increases in check, there is the potential for the hunters or fishermen to simply catch too many of their prey, reducing the population to a point from which it cannot fig. 1 map of the faroe islands showing its location between iceland, norway and scotland. map by c. duplechin, louisiana state university. environmental change and the faroese pilot whale hunt polar research 29 2010 430–438 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 431 return. when this happens the species, at least as a resource, is extinct. we can compare the grindadráp to a similar north atlantic pilot whale drive that occurred in newfoundland during the 20th century (dickinson & sanger 2005; fielding 2007a). newspapers from the mid-1800s in newfoundland archives show that the occasional pilot whale drive was an important source of supplemental income for residents of the island’s south-eastern peninsula, who earned a share of the proceeds from producing and selling whale oil (cranford & hillier 1995). in 1951 the newfoundland pilot whale drive was organized commercially, and 3100 whales were taken that year. whaling records in newfoundland show that landings increased with the demand for oil and meat, to a peak of 9794 in 1956 (pinhorn 1976). a lucrative market was found in the production of whale-based feed for the province’s new mink and fox fur farms, encouraging more whale drives. by contrast, the grindadráp is forbidden to become commercial by faroese law. rather, a centuriesold process of free distribution is mandated, ensuring that the meat and blubber are given first to the participants in the drive and slaughter, and second to the residents of the district in which the kill took place. this system is designed to provide food for the faroese people while not depleting the resource through unnecessary extraction. conducting an accurate count of the eastern north atlantic pilot whale population has been an ongoing project for faroese and international biologists. there are approximately 778 000 pilot whales in the eastern north atlantic stock (buckland et al. 1993). the faroese ministry of fisheries regulates the number of pilot whales killed annually. the minister’s office can forbid future grindadráp if it is known that enough meat and blubber have already been stored (bjørn kalsø, minister of fisheries, pers. comm.). after 425 years of recorded grindadráp occurring in the faroe islands, over-extraction does not seem to be a threat and will probably not lead to the abandonment of the grindadráp, as it did with the pilot whale drive industry in newfoundland. protest and boycott although the grindadráp has been well documented in travellers’ accounts and cultural studies of the faroe islands for centuries (joensen 1976; wylie 1981; sanderson 1992), it remained relatively obscure to the public outside of scandinavia until the mid-1980s. sanderson (1990) described the quick shift that the grindadráp made from a relatively unknown method of food procurement and source of national distinctiveness and pride, to an alleged crime against nature and target of international protest. i will summarize and expand upon sanderson’s detailed chronology here, beginning in 1981 when the activity was “discovered” by international environmental organizations. • 1981. greenpeace representatives visit the faroes to document the (now ceased) fin whale (balaenoptera physalus) catch. their visit coincides with three large grindadráp. the representatives’ final report to greenpeace (glover 1981) focuses primarily (and critically) upon the grindadráp. • 1984. a danish television company produces a documentary film about the grindadráp that increased its visibility within europe. • 1985. at the annual meeting of the iwc in bournemouth, uk, the topic of the grindadráp is brought up, although the iwc maintains its stance that it would not regulate the take of small cetaceans. campaign letters from environmental organizations and journalistic pieces critical of the grindadráp are published this year. as a result of these campaigns, letters and preprinted postcards begin to arrive at the office of the prime minister in tórshavn. • 1986. paul watson, founder of the environmental organization sea shepherd, makes a highly publicized visit to the faroes with the intention of stopping the grindadráp. faroese regulations regarding the grindadráp are changed dramatically with the goal of ensuring a more humane death for the whales. • 1991. the high north alliance is formed, to “protect the rights of whalers, sealers and fishermen to harvest renewable resources in accordance with the principle of sustainable management” (high north alliance 2008). • 1993. grindamannafelagið (the faroese pilot whalers’ association) is formed to establish regulations for more humane killing methods in the grindadráp. also this year environmental organizations begin calling for a boycott of faroese products, especially seafood, which makes up over 96% of the country’s exports (statistics faroe islands 2005). • 1995. the iwc commends the improvements in killing methods that were instituted on the recommendation of the grindamannafelagið. • 2000. paul watson returns to the faroes with more international press coverage than on the previous visit, and patrols the coastline with the goal of driving pods of whales away from the islands, thereby preventing the grindadráp. • present. the occasional chain e-mail is circulated, showing photographs of bloodstained faroese harbours or pilot whale carcasses in various states of being processed. however, no major boycott or protest is currently promoted. the environmental organizations greenpeace, sea shepherd and the whaleman foundation maintain their positions against the grindadráp. environmental change and the faroese pilot whale hunt polar research 29 2010 430–438 © 2010 the author, journal compilation © 2010 blackwell publishing ltd432 the world wildlife fund denmark (wwf) has prepared a standard response to enquiries that refers to the sustainability of the grindadráp, its long history in faroese culture, and the efforts made by the faroese authorities to reduce the suffering of the whales that are killed. the statement concludes by noting that “wwf is a conservation organization and the question of cruelty of the pilot whale hunt is not a conservation issue” (christina sabinsky, pers. comm.). in the recent past, and especially during the late 1980s and early 1990s, it seemed to some faroese that the international protests and threatened boycott might require the cessation of the grindadráp. in august 2005, ólavur sjurðarberg, president of grindamannafelagið, remarked that the protest was the biggest threat to the continuance of the grindadráp. this opinion was echoed as recently as march 2008 by rolf guttesen, a faroese geographer at the university of copenhagen (pers. comm.). as a direct result of the protest, the grindamannafelagið was created and led efforts to implement changes that improved killing methods and further ensured sustainability. in this regard, the protest had a positive effect in the faroe islands, and faroese writers have credited the anti-whaling organizations with instigating these changes (e.g., guttesen 1996). today, most anti-whaling organizations, especially american and australian ones, direct their efforts against the so-called scientific whaling conducted by japan in the southern ocean, and, to a lesser degree, the commercial whaling conducted by norway and iceland. the faroes have not been subject to much direct protest recently, nor have the proposed boycotts had any noticeable impact on the faroese economy. it seems then that the protest has not ended—or even lessened—the occurrence of the grindadráp in the faroe islands. rather, its effect was to call attention to some areas in which the grindadráp could be improved, and to instigate the necessary improvements. pollution as high trophic-level predators, pilot whales accumulate high levels of mehg, persistent organic pollutants (pops) and other toxins in their muscle and blubber tissue (dam & bloch 2000). many whale species, both baleen and toothed whales, in a variety of geographical areas have been found to have elevated levels of marine contaminants in their tissues (hansen et al. 1990; frodello et al. 2000; ross et al. 2000; hoekstra et al. 2002). some of these contaminants occur naturally. mehg, for example, results when elemental mercury—either occurring naturally as it degasses from the earth’s crust, or anthropogenically in the form of air pollution—is deposited into the ocean and is methylated in the marine sediment environment by sulfate-reducing bacteria (morel et al. 1998). industry, especially coal-fired electricity generation, is a major contributing source of anthropogenic mercury in the atmosphere. as such, industrialized nations often experience localized deposition of mercury in their waterways (joensuu 1971; morel et al. 1998). however, mercury is commonly found far from any source of industrial pollution (morel et al. 1998; boening 2000). faroese scientists and laypeople alike often make the point that their nation is “without responsibility with regard to the marine pollution” (weihe & joensen 2008: 3), placing the blame on other, more industrialized countries for the problems that have affected them and the whales upon which they rely as a food source. beginning with unicellular organisms living in marine sediments, mehg is biomagnified as it is transported up the food chain, becoming most concentrated in seabirds and marine mammals (morel et al. 1998; gray 2002). the concentration of mercury in an organism’s tissue varies with lipid content; whales, of course, are most susceptible, having a thick layer of blubber covering most of their bodies. humans who eat meat and other tissue from high trophic-level marine animals are exposed to levels of mehg far in excess of the recommended maximum of 0.5–1 ppm (morel et al. 1998). many northern peoples have been found to have a high rate of exposure to marine toxins as a result of food-borne contamination (weiss 2008). the problem of mercury and other contaminants is an issue throughout the circumpolar world. in 2006 the arctic council, of which the faroe islands are a part, formed a working group called the arctic contaminants action program from an existing steering committee that had already been investigating the problem of contaminated traditional food sources of the northern peoples (arctic council 2008). this working group calls mercury “a priority pollutant”. likewise, the arctic monitoring and assessment programme emphasizes the risk of increased exposure to mehg and pops, associated with a diet that includes high quantities of meat and blubber from marine mammals (amap 2009). the faroe islands have led the circumpolar world in research into the problem of mercury contamination and human health (grandjean et al. 2007). since 1985, the faroese hospital system has chosen 1751 children at or before birth in three cohorts to take part in a long-term study, known as the children’s health and environment in the faroes (chef) project, to determine the effects of mehg and other marine contaminants (grandjean & weihe 2008). children in the first cohort are now turning 25 years old. through their participation they have provided the medical researchers with much important information. environmental change and the faroese pilot whale hunt polar research 29 2010 430–438 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 433 in contrast to pops, mehg levels in the human body decrease with time and reduced exposure (weihe & joensen 2008). when humans eat pilot whale blubber they absorb the pops stored there, and these toxins stay in their systems for many years. women who were exposed to pops as young girls can still pass on the contaminants to their own children. for this reason, dr weihe’s 1998 dietary recommendations stated that it was best for females not to eat blubber at all until they have reached an age at which they no longer plan to have children (weihe 1998). this was a radical departure from the long-standing nutritional orthodoxy in the faroe islands—among both the public and the community of medical professionals—that pilot whale meat and blubber were essential parts of the diet for healthy faroese people (weihe & joensen 2008). ten years after issuing the first dietary recommendations, dr weihe and the faroe islands’ chief medical officer, dr høgni joensen, went one step further. whereas the 1998 recommendations allowed for one or two meals of pilot whale meat and blubber per month for healthy adults who are not going to become pregnant, the 2008 recommendations stated that: pilot whales today contain contaminants to a degree that neither meat nor blubber would comply with current limits for acceptable concentrations of toxic contaminants . . . from the latest research results, the undersigned consider that the conclusion from a human health perspective must now be as follows: it is recommended that pilot whale is no longer used for human consumption. (weihe & joensen 2008: 3, emphasis from the original) it seems, then, that pollution may be the obstacle that the grindadráp cannot overcome. despite environmentalist efforts, as more developing nations industrialize, marine pollution is likely to increase. as the meat and blubber become more contaminated, their risk will increasingly outweigh their benefits. this is not to say that the faroese will give up their “national dish” easily. as has been shown in a variety of contexts, food is a powerful reminder of a culture’s distinctiveness and national identity (e.g., wilk 1999; cusack 2000; raento 2006). just as in other northern maritime communities (e.g., o’neil et al. 1997), the cultural connection to traditional local food in the faroes is strong. initial analysis of data obtained through interviews with faroese youth as recently as september 2009 indicate that the meat and blubber of the pilot whale are still valued for their healthful qualities, and are still consumed, albeit at reduced quantities since the 1998 and 2008 recommendations were released. the grindadráp is still seen by many as a valuable part of faroese culture. one possible outcome that could balance the cultural connection to pilot whale meat and blubber with the health risks of its consumption would be to retain the food as something of a ceremonial meal, eaten only (or primarily) at special occasions such as weddings, birthdays and the faroese national holiday, ólavsøka. initial results from ongoing research indicate that this shift from pilot whale meat and blubber as an ordinary meal to a ceremonial meal is occurring to some degree, especially among the young urban population in tórshavn. the faroese cling tightly to their culture, but they also take seriously the advice of their public health professionals. the third cohort of children in the chef project, born between 1998 and 2000, showed lower concentrations of mehg than the first cohort, born in 1986 and 1987. the directors of the project attribute this decrease to the obedience of the children’s mothers in following the dietary recommendations (grandjean & weihe 2008). similar reductions have been measured in human populations throughout the circumpolar north—a trend that experts attribute to three factors: changes in diet, changing levels of contamination in the environment and increasing availability of public health information in traditional communities (amap 2009). levels of environmental contamination are not declining quickly enough to change the direction of advice given by faroese health authorities, however. dr weihe believes that the results of his study and the revised dietary recommendations will lead to a cessation of the grindadráp, although he does not press for legislation outlawing the practice. the reduction in the consumption of whale meat and blubber should be based on an understanding for the toxicological risks. not a decision from the politicians. i think what will happen is that the women first will stop eating it and . . . the men will follow. however, my best prediction is that sporadic killings will take place over the next decade and [then] it will be a forgotten culture. (pál weihe, pers. comm.) it appears that the pollution may accomplish something that protest and the threat of over-extraction were unable to do in the faroe islands—it could lead to the end of the grindadráp. alternatives the conflict involved when the same food has both beneficial and detrimental qualities has been studied with regard to the faroese diet, with the conclusion that one can exercise good judgment in choosing foods that are high in benefits such as fatty acids, but low in contaminants (budtz-jørgensen et al. 2007). the fatty acids, antioxidants, vitamins and protein found in the pilot whale meat and blubber must be replaced with nutrients found elsewhere. environmental change and the faroese pilot whale hunt polar research 29 2010 430–438 © 2010 the author, journal compilation © 2010 blackwell publishing ltd434 in 2002, the grindadráp was found to supply 30% of the meat produced locally in the faroe islands (anonymous 2002). although the grindadráp is a non-commercial activity—that is, no money changes hands throughout the process of killing and butchering the whales, or distributing and preparing the meat and blubber—its economic value can be “measured against the economic and environmental costs of importing the same amount of food” (anonymous 2002: 13). when one considers the possible cessation of the grindadráp and the gap that its absence would leave in the faroese meat supply, one must consider the environmental as well as the economic costs of filling that gap. three alternative methods of food acquisition are currently being discussed in the faroe islands: an increase of meat imports, an intensification of local livestock production, and the shifting of some of the fish that is currently exported to being made available for local consumption. increased imports the major country of origin for imports to the faroe islands is denmark, with which it shares a crown and a currency (dkk), although the national statistics bureau of the faroe islands treats trade with denmark as it does trade with any other foreign country. in 2005, the faroes imported over dkk 1 billion (usd 216 million) worth of goods from denmark. compare this with the countries of origin for the next-highest levels of imports: spain at dkk 298 million (usd 56.6 million), germany at dkk 264 million (usd 50.2 million) and sweden at dkk 229 million (usd 43.6 million). put another way, the faroe islands receives 26.7% of their total value of imports from denmark, compared with 7% from spain, 6.2% from germany and 5.4% from sweden (statistics faroe islands 2006). the faroe islands also have long-distance trade partners, often importing meat—especially lamb—from as far away as new zealand (guttesen 1996). as the costs of food and fuel increase, these import costs will certainly increase as well, even if the amount of food imported remains constant. if the faroe islands were to increase their imports to fill the gap left by the cessation of the grindadráp, they would also incur higher cost for transportation and would be contributing, through the increased use of fossil fuels, to the same sources of marine pollution that would have led them to abandon the grindadráp in the first place. intensification of local livestock production livestock has been an important part of the faroese food economy since the islands were first settled. when the norse arrived in the faroe islands during the 9th century, they brought primarily sheep, but also cattle, and established european grazing management practices (thomson et al. 2005). their activities transformed the pristine landscape to which they had arrived, but their limited numbers and experience working in northern settings led to a sustainable use of the local resources (edwards 2005). the population has increased dramatically since the time of norse settlement. the land area of the faroes, of course, has not increased, and remains 1399 km2 today, just as it was in the 9th century. as the population increased, so did the intensity of farming, well into the 19th century. in 1865 farming (including livestock raising) was the main occupation in the faroes, employing some 68% of the workforce. in 1996, farming employed only 2% of the workforce, with commercial trades and services making up the largest sector of the economy (guttesen 1996). livestock management is still an important industry in the faroe islands. through extensive government programmes, the faroese dairy industry has made the faroe islands self-sufficient in milk production, although the dairies are supported through the importation of hay and supplemental fodder from iceland and other european countries (guttesen 1996). government programmes encourage the consolidation of dairy farms into fewer, larger holdings to maximize milk production. though the number of dairy farmers has decreased from 111 to 51 since 1990, the number of dairy cattle has basically remained constant, from 2070 in 1990 to 2093 in 2007 (statistics faroe islands 2008). although sheep still greatly outnumber the human inhabitants, their importance to the economy of the faroe islands is in decline. mutton and lamb imported from iceland and new zealand supplement local production, but cultural preferences allow locally raised meat to sell for a much higher price. guttesen suggested that the faroe islands could support a larger sheep industry, but that cultural acceptance of a shift from traditionally pastoral to industrial sheep rearing would need to happen first (guttesen 1996). if the faroese are to use their land resources to replace the meat lost by a potential closure of the grindadráp, they will have to reassert livestock as a major industry while maintaining the sustainable practices with which faroese farming was begun by the original norse settlers. guttesen has suggested that the current pattern of land tenure, which has led to a scattering of tiny, irregularly shaped parcels that are incompatible with modern farm machinery, needs to be reformed (guttesen 1996). whether society will accept these changes, and the associated modifications that they would produce in the faroese landscape, is yet to be seen. environmental change and the faroese pilot whale hunt polar research 29 2010 430–438 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 435 increased consumption of local fish some fish and sea mammals show much higher levels of mehg and other contaminants than do other species. dr weihe states that the concentration of mercury is so high in pilot whale meat that, “for every portion of whale you could eat 100 portions of cod” (pál weihe, pers. comm.). he advocates replacing whale meat in the faroese diet with locally caught fish. in 2004 the faroe islands exported over dkk 3.4 billion (usd 659 million) of fish, which comprised over 94.3% of their total exports (statistics faroe islands 2005). perhaps some of these exports could be kept at home for local consumption. a shift from foreign to local markets for a portion of the faroese fish catch would provide locally produced food that is high in protein and fatty acids (as are pilot whale meat and blubber), but low in mehg and other contaminants, and would not incur the environmental or economic cost of transporting the products from europe or beyond. nor would the limited area of available land be taxed by higher usage in the farming and livestock industries. the faroese economy would be affected by the loss of a portion of foreign trade and export power, but if the fish were sold in faroese markets, the local economy would also be stimulated by the addition of a cash commodity in place of a non-commercial meat source. the economic impact would then be transferred to the individuals who buy the fish in place of the whale meat that they had formerly received at no cost. the loss of any natural resource must be accompanied by increased cost as systems adjust to fill the gap left by its absence. conclusion the world should be watching the reaction of the faroe islands to the problem of marine pollution. as pioneers in the cross-disciplinary field of island studies point out, small islands are often at the frontline of environmental change (royle 2001; rapaport 2006). the faroes specifically, and the insular north more broadly, are in a position to inform the world through their own experiences of the potential risks of our increasingly polluted marine environment. ólafur ragnar grímsson, the president of iceland, recently pointed out that the north is positioned to be an advance indicator of global environmental change to the world (grímsson 2008). a point often overlooked by the media and science alike, however, is that environmental change is not restricted to global warming alone. the build-up of marine contaminants is one of many environmental changes that shares causal elements with global warming, and could potentially affect northern—and eventually, worldwide—ways of life just as severely. reire (2008) showed that the public is eager for more information about environmental change and is willing, to some degree, to make behavioural changes that will decrease the negative effects of human activity on the environment. environmental forces, often in human-modified forms, engender adaptive changes in human behaviour—which in turn affect the environment. only with a truly systematic approach to our analysis will we be able to make sense of the interactive cycles of human society and the environment. the faroese are proud of the grindadráp. for centuries it has been a national symbol of faroese identity, only briefly losing this status during the protests of the 1980s and 1990s. jóan pauli joensen, in one of the earliest academic treatments of the grindadráp in english, calls it “a distinctive cultural characteristic for the faroe islands” (joensen 1976: 5). sanderson, in her textual history of the grindadráp, found evidence that it had long been singled out as a “characteristic feature of faroese culture” and “an established symbol of faroese national identity” (sanderson 1992: 1). as with other whaling cultures, the grindadráp has inspired the production of an extensive material culture (hough 1933; lantis 1938; erikson 1999; arno 2005; figs. 2–3). whaling equipment is often displayed in houses as décor, taking it beyond its mere utilitarian purpose. in addition to the objects of material culture it has produced, the grindadráp has inspired authors, poets and songwriters in the faroe islands for centuries (see sanderson 1992). the grindadráp has existed for centuries and has overcome the threats of closure from over-extraction and international protest. however, it appears that the problem of environmental pollution leading to marine contaminants in pilot whale meat and blubber may be too great for the grindadráp to withstand. if the public abides fig. 2 painting by faroese artist sámal joensen-mikines depicting the frenzied action as a pod of whales is driven and killed at the water’s edge. (courtesy of listasavn føroya, tórshavn, faroe islands, and kári j. mikines, son of the artist.) environmental change and the faroese pilot whale hunt polar research 29 2010 430–438 © 2010 the author, journal compilation © 2010 blackwell publishing ltd436 by the new dietary recommendations it is likely that the faroe islands will witness an ending of the grindadráp, as dr weihe predicted, within just a few years. along with the loss of a locally valued national tradition, the cessation of the grindadráp will lead to a loss of an important free food source. faroese culture will survive, for although a culture may produce a rich variety of materials, traditions and practices, its existence is not dependent upon any one of these artefacts. faroese national identity can endure without the grindadráp, but attention must be given to identifying a sustainable source of food to replace the meat and blubber lost in its closure. the solution will likely not lie in any one of the proposed replacements alone— increased imports, intensified local agriculture and livestock industries, or increased consumption of local fish—but rather in a combination of all three. and although a dinner of wind-dried pilot whale meat, salted blubber and boiled potatoes has long been considered the faroese national dish, another meal will rise to take its place, will be embraced by the culture, and will be enjoyed for years to come. flexibility and diversification will be key attributes of an economically successful and nutritionally balanced future for the faroe islands. acknowledgements the author wishes to express thanks to the northern research forum for hosting the meeting for which this paper was originally prepared. additional thanks are due to the university of the faroes and the faroese museum of natural history for funding four field seasons in the faroe islands and providing housing, contacts and camaraderie. this paper could not have been completed without the advice and wisdom of dorete bloch, kate sanderson, ólavur sjúrðarberg, pál weihe, paul watson, jóan pauli joensen, bjørki geyti, kent mathewson, william rowe, craig colten, r. eugene turner and jeffrey gritzner. additional thanks to klaus dodds and steve royle for their insightful comments and suggestions as reviewers. references ackrén m. 2006. the faroe islands: options for independence. island studies journal 1, 223–228. amap 2009. arctic pollution 2009. oslo: arctic monitoring and assessment programme. anonymous 2002. the faroe islands—a north atlantic perspective on sustainable development. tórshavn: faroese prime minister’s office. arctic council 2008. acap: arctic contaminants action program. accessed on the internet at http://acap.arctic-council.org on 18 march 2010. arno a. 2005. cobo and tabua in fiji: two forms of cultural currency in an economy of sentiment. american ethnologist 32, 46–62. boening d.w. 2000. ecological effects, transport, and fate of mercury: a general review. chemosphere 40, 1335–1351. buckland s.t., bloch d., cattanach k.l., gunnlaugsson t., hoydal k., lens s. & sigurjónsson j. 1993. distribution and abundance of long-finned pilot whales in the north atlantic, estimated from nass-1987 and nass-89 data. report of the international whaling commission 14, 33–50. budtz-jørgensen e., grandjean p. & weihe p. 2007. separation of risks and benefits of seafood intake. environmental health perspectives 115, 323–327. cranford g. & hillier r. 1995. potheads and drumhoops: a folk history of new harbour, trinity bay. st. john’s, nl: flanker press. cusack i. 2000. african cuisines: recipes for nation-building? journal of african cultural studies 13, 207–225. dam m. & bloch d. 2000. screening of mercury and persistent organochlorine pollutants in long-finned pilot whale (globicephala melas) in the faroe islands. marine pollution bulletin 40, 1090–1099. dickinson a.b. & sanger c.w. 2005. twentieth-century shore-station whaling in newfoundland and labrador. montreal: mcgill–queen’s university press. edwards k. 2005. “on the windy edge of nothing”: a historical human ecology of the faroe islands. human ecology 33, 585–596. erikson p.p. 1999. a-whaling we will go: encounters of knowledge and memory at the makah cultural and research center. cultural anthropology 14, 556–583. fielding r. 2007a. a comparison of pilot whale drives in newfoundland and the faroe islands. the scottish geographical journal 123, 160–172. fielding r. 2007b. peacefully watching the slaughter: whale hunting in the faroe islands. the explorer’s journal 85, 30–37. frodello j.p., roméo m. & viale d. 2000. distribution of mercury in the organs and tissues of five toothed-whale species of the mediterranean. environmental pollution 108, 447–452. fig. 3 the grindaknívur—pilot whaling knife —is “the pilot whale hunt’s most distinguished piece of equipment and . . . one of the foremost faroese contributions to nordic artistic craftsmanship” (joensen 1976: 15). even the most ornately decorated knife is built strong enough to cut through a pilot whale’s blubber and muscle, and to break its spinal cord (fielding 2007b). environmental change and the faroese pilot whale hunt polar research 29 2010 430–438 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 437 http://acap.arctic-council.org glover m. 1981. faroese fin whale campaign—1981. london: greenpeace. grandjean p. & weihe p. 2008. children’s health and the environment in the faroes. accessed on the internet at http://www.chef-project.dk on 18 march 2010. grandjean p., bellinger d., bergman å., cordier s., davey-smith g., eskenazi b., gee d., gray k., hanson m., van den hazel p., heindel j.j., heinzow b., hertz-picciotto i., hu h., huang t.t.-k., kold jensen t., landrigan p.j., mcmillen i.c., murata k., ritz b., schoeters g., skakkebæk n.e., skerfving s. & weihe p. 2007. the faroes statement: human health effects of developmental exposure to chemicals in our environment. basic & clinical pharmacology & toxicology 102, 73–75. gray j.s. 2002. biomagnification in marine systems: the perspective of an ecologist. marine pollution bulletin 45, 46–52. grímsson ó.r. 2008. nordic interests and the future of the north: a speech synopsis based on rapporteurs’ notes. position paper for the 5th northern research forum open assembly, 24–27 september, oslo. available on the internet at: http://www.nrf.is/open%20meetings/ anchorage/position%20papers/positionpapers.htm. guttesen r. 1996. the faeroe islands topographical atlas. copenhagen: royal danish geographical society. hansen c.t., nielsen c.o., dietz r. & hansen m.m. 1990. zinc, cadmium, mercury and selenium in minke whales, belugas and narwhals from west greenland. polar biology 10, 529–539. high north alliance 2008. the high north alliance. accessed on the internet at http://www.highnorth.no on 18 march 2010. hoekstra p.f., o’hara t.m., pallant s.j., solomon k.r. & muir d.c.g. 2002. bioaccumulation of organochlorine contaminants in bowhead whales (balaena mysticetus) from barrow, alaska. archives of environmental contamination and toxicology 42, 497–507. hough w. 1933. northwest coast spliced harpoon shafts. american anthropologist 35, 204. joensen j.p. 1976. pilot whaling in the faroe islands. ethnologia scandinavica 1976, 1–42. joensuu o.i. 1971. fossil fuels as a source of mercury pollution. science 172, 1027–1028. lantis m. 1938. the alaskan whale cult and its affinities. american anthropologist 40, 438–464. morel f.m.m., kraepiel a.m.l. & amyot m. 1998. the chemical cycle and bioaccumulation of mercury. annual review of ecological systems 29, 543–566. o’neil j.d., elias b. & yassi a. 1997. poisoned food: cultural resistance to the contaminants discourse in nunavik. arctic anthropology 34, 29–40. pinhorn a.t. 1976. living marine resources of newfoundland–labrador: status and potential. bulletin of the fisheries research board of canada 194, 49. raento p. 2006. changing food culture and identity in finland. in p. raento (ed.): finnishness in finland and north america: constituents, changes, and challenges. toronto: aspasia books. rapaport m. 2006. eden in peril: impact of humans on pacific island ecosystems. island studies journal 1, 109–124. reire g. 2008. the relationship between humans and the environment from the latvian perspective. position paper for the 5th northern research form open assembly, 24–27 september, oslo. available on the internet at: http://www.nrf.is/open%20meetings/anchorage/ position%20papers/positionpapers.htm. ross p.s., ellis g.m., ikonomou m.g., barrett-lennerd l.g. & addison r.f. 2000. high pcb concentrations in free-ranging pacific killer whales, orcinus orca: effects of age, sex and dietary preference. marine pollution bulletin 40, 504–515. royle s. 2001. a geography of islands: small island insularity. london: routledge. sanderson k. 1990. grindadráp: the discourse of drama. north atlantic studies 2, 196–204. sanderson k. 1992. grindadráp: a textual history of whaling traditions in the faroes to 1900. mph thesis, university of sydney. sanderson k. 1994. “grind”—ambiguity and pressure to conform: faroese whaling and the anti-whaling protest. in m. freeman & u.p. kreuter (eds.): elephants and whales: resources for whom? pp. 187–201. basel: gordon and breach. statistics faroe islands 2005. faroe islands in figures 2005. tórshavn: hagstova føroya. statistics faroe islands 2006. faroe islands in figures 2006. tórshavn: hagstova føroya. statistics faroe islands 2008. statistics faroe islands. accessed on the internet at http://www.hagstova.fo on 26 august 2008. thomson a.m., simpson i.a. & brown j.l. 2005. sustainable rangeland grazing in norse faroe. human ecology 33, 737–761. van ginkel r. 2005. killing the giants of the sea: contentious heritage and the politics of culture. journal of mediterranean studies 15, 71–98. weihe p. 1998. diet recommendation concerning pilot whale meat and blubber—faroe islands august 1998. tórshavn: faroese food and veterinary agency. weihe p. & joensen h.d. 2008. recommendations to the government of the faroe islands concerning the pilot whale. (english translation released 1 december 2008.) tórshavn: landslægen. weiss l.d. 2008. background paper on the human health consequences of climate change in the circumpolar north. position paper for the 5th northern research forum open assembly, 24–27 september, oslo. available on the internet at: http://www.nrf.is/open%20meetings/ anchorage/position%20papers/positionpapers.htm. wilk r. 1999. “real belizean food”: building local identity in the transnational caribbean. american anthropologist 101, 244–255. wylie j. 1981. grindadráp. in j. wylie & d. margolis (eds.): the ring of dancers: images of faroese culture. philadelphia: university of pennsylvania press. environmental change and the faroese pilot whale hunt polar research 29 2010 430–438 © 2010 the author, journal compilation © 2010 blackwell publishing ltd438 http://www.chef-project.dk http://www.nrf.is/open%20meetings http://www.highnorth.no http://www.nrf.is/open%20meetings/anchorage http://www.hagstova.fo http://www.nrf.is/open%20meetings no job name organic carbon and microbial biomass in a raised beach deposit under terrestrial vegetation in the high arctic, ny-ålesund, svalbard takayuki nakatsubo1, shinpei yoshitake1, masaki uchida2, masao uchida3,4, yasuyuki shibata3 & hiroshi koizumi5 1 graduate school of biosphere science, hiroshima university, higashi-hiroshima, 739-8521, japan 2 national institute of polar research, itabashi-ku, tokyo 173-8515, japan 3 institute of oceanographic research for global changes, japan agency for marine-earth science and technology, yokosuka 237-0061, japan 4 nies-terra ams facility, environmental chemistry division, national institute for environmental studies, tsukuba 305-8506, japan 5 institute for basin ecosystem studies, gifu university, gifu 501-1193, japan abstract raised beach deposits are widespread on the north-western coast of spitsbergen, svalbard. to elucidate the importance of these deposits in an ecosystem carbon cycle, we measured the concentrations of organic carbon and adenosine 5-triphosphate (atp; an index of living microbial biomass) in a raised beach deposit found under terrestrial vegetation in ny-ålesund. a shell in the deposit found at a depth of ca. 20 cm below the ground surface had a (not calibrated) 14c age of 11080 � 140 yr bp, whereas soil organic carbon in the same deposit showed an older 14c age (22380 � 90 yr bp). organic carbon concentration in the layer of 20–40 cm belowground was about 1–2%, which was comparable to those in shallower mineral soil layers. results of atp analyses suggested that low but non-negligible amounts of microorganisms existed in the deposit. the proportion of biomass carbon to soil organic carbon tended to decrease with increasing depth, suggesting that organic carbon in the deep layer was less available to microorganisms than that in the shallow layers. keywords atp; high arctic; microbial biomass; organic carbon; raised beach deposits; svalbard. corresponding author takayuki nakatsubo, graduate school of biosphere science, hiroshima university, higashi-hiroshima, 739-8521, japan. e-mail: kuyakat@hiroshima-u.ac.jp doi:10.1111/j.1751-8369.2008.00037.x raised beaches are widely distributed along the northwestern coast of spitsbergen. they are the product of rebound following episodes of isostatic depression under pleistocene ice sheets in the nearby barents sea and in glaciated areas of svalbard (forman et al. 1987). using radiometric and amino-acid dating, geologists have documented quaternary depositional episodes and the relative sea-level history in detail (miller 1982; forman & miller 1984; forman et al. 1987). in contrast, little is known about the ecological importance of raised beach deposits. several studies have recognized widely varying subsurface microbial communities that use forms of ancient sedimentary organic carbon (macnaughton et al. 1999; petsch et al. 2001). more recently, dutta et al. (2006) and zimov et al. (2006) reported that ancient organic carbon in siberian loess deposits (21000–25000 yr bp) began to decompose immediately upon thawing. the contribution of raised beach deposits to the terrestrial carbon cycle might be considerable if the deposits contain a large amount of organic carbon useful to soil organisms. as part of a study of the carbon cycle in a glacier foreland in ny-ålesund, svalbard (nakatsubo et al. 2005), we determined the amount and 14c age of organic carbon contained in a raised beach deposit found under terrestrial vegetation. in addition, we measured the adenosine 5-triphosphate (atp) concentration in the deposit to determine the living microbial biomass. materials and methods study site and sampling a raised beach deposit containing seashells was found on the bank of a river flowing through the glacier foreland of austre brøggerbreen (east brøgger glacier) near ny-ålesund in north-western spitsbergen, svalbard, norway (about 20 m a.s.l.; fig. 1). the site had well polar research 27 2008 23–27 © 2008 the authors 23 mailto:kuyakat@hiroshima-u.ac.jp developed vegetation consisting mainly of saxifraga oppositifolia l. and mosses. the means of annual air temperature and annual amounts of precipitation in this area for 1995–1998 were, respectively, –5.5°c and 362 mm. this site is near the study sites of some previous studies of the carbon cycle in this area (site 3 in nakatsubo et al. 1998, 2005). roth & boike (2001), who measured the thermal dynamics in soils near the study site, reported that the active layer thawed gradually during summer to depths between 0.9 and 1.1 m. in august 2005, surface soils covering the bank were carefully removed to expose the soil profile, including layers of the beach deposit. considerable care was taken to avoid disturbing the soil structure. soil samples were taken using a steel cylinder (diameter 5 cm, 50 cm3) from 0–2.5 cm, 10–12.5 cm, 20–22.5 cm, 30–32.5 cm, and 40–42.5 cm of mineral soil layers. to prevent contamination, the steel cylinder was sterilized after each sample was taken. these samples were air-dried (for cn analysis) or freeze-dried (for carbon dating or atp analysis) in the laboratory at ny-ålesund and brought back to japan. the seashells were observed only in a 5–6-cm-thick reddish silt layer, which was 20–25 cm belowground. they were also collected for carbon dating. the soil samples for cn analysis were passed through a 2-mm mesh sieve to remove gravel. root fragments were removed from the samples using a forceps. total carbon and nitrogen concentrations of the samples were measured using a cn analyser (perkin-elmer 2400 ii; perkin-elmer inc., wellesley, ma, usa). organic carbon contents were determined by removing carbonate from samples according to sollins et al. (1999). one ml of 5% phosphoric acid was added to the soil (200–1000 mg dry wt.), which was then left at 25°c for 6 h. the procedure was repeated until co2 stopped bubbling from the soil. the samples were freeze-dried, with subsequent carbon content analysis using the cn analyser. 14c ages of shell and soil organic carbon the ams 14c dates are used to build the chronology of vertical soil profiles. shell samples were cleaned by soaking them in a 30% hydrogen peroxide solution to remove adherent contaminants derived from soil organic carbon; samples were then reacted with 100% phosphoric acid within evacuated glass vessels at the temperature of 25°c. the graphitization of soil organic carbon was carried out according to a procedure used by uchida et al. (2004, 2005). the 14c data were acquired at the niesterra ams facility at the national institute for environmental studies (tanaka et al. 2000; yoneda et al. 2004). atp analysis the concentration of atp in the deposits was determined using the method of jenkinson & oades (1979) with some modification. freeze-dried soil samples of 1 g (dry wt.) in 15 ml plastic centrifuge tubes were extracted by addition of 5 ml of the tca reagent (a mixture of 0.5 m trichloroacetic acid and 0.25 m di-sodium hydrogen orthophosphate anhydrous [na2hpo4]) followed by immediate ultrasonic homogenization (astrason 3000; misonix inc., farmingdale, ny, usa) at 150 w for 2 min. tubes were kept in ice water during this procedure. after centrifugation of soil suspensions at 5000 rpm for 15 min at 5°c, 50 ml of the clear supernatant was carefully removed using a sterilized pipette to another centrifuge tube. then, 4.95 ml of 0.025 m hepes at ph 7.0 solution was added to the tubes and 100 ml was used for atp analysis. sample atp concentrations were quantified using the luciferin–luciferase enzyme method with light emission austre broggerbreen 500 m 20 m 40 m 60 m 80 m 10 0 m sea (kolhamna) spitsbergen 15 20 25 80 78 svalbard 0 50 100 km ny-alesund sampling point bayelva fig. 1 map showing the study site. carbon and microbes in a high arctic raised beach t. nakatsubo et al. polar research 27 2008 23–27 © 2008 the authors24 measured using an atp tester (af-70; dkk-toa corp., tokyo). extraction efficiencies were determined by adding known amounts of atp to soil samples. results and discussion at all depths, organic carbon made up most of the total carbon (table 1). the difference in the concentration between total and organic c was larger in the deep layers than in the shallow layers, suggesting that deep layers contain large amounts of carbonate. the concentration of organic carbon did not differ significantly among layers (scheffe’s f, p > 0.05). the 14c ages of soil organic carbon (soc) were dated from the soil surface to 40–42.5 cm. they ranged from 5840 yr bp (0–2.5 cm) to 35890 yr bp (30–32.5 cm) (table 2). the 14c age profile of soc was older with increased depth, except for the 30–32.5 cm layer, where the 14c age of soc was older than that in the 40–42.5 cm layer. however, a large age difference was found between the seashell and soc in the 20–22.5 cm layer. the seashell was dated on the age of 11080 yr bp, whereas soc in the same layer showed a much older date (22380 yr bp). the 14c ages of the seashell (11080 yr bp) agree well with those obtained in a study conducted by forman & miller (1984), who reported that terraces on the peninsula of brøggerhalvøya below 44 m had been formed during the last 12000 years. this large difference in the 14c age between the seashell and soc might be partly explained by contamination with 14c-free fossil carbon such as coal particles, which were widely observed in this area. another possible factor that might affect the measured 14c age is cryoturbation, which causes vertical movement of unfrozen soil materials. michaelson et al. (1996) reported that cryoturbation played an important role in the distribution of soil carbon stocks in tundra soils of arctic alaska. the reversion of the 14c age that was observed between 30–32.5 cm and the 40–42.5 cm layers might also be explained by cryoturbation. the results of this study showed that organic carbon in this area has two distinct origins: old organic carbon of beach deposits and more recently deposited organic carbon fixed by terrestrial vegetation. the deep layers contained a large amount of old carbon. the total amount of organic carbon contained in the 10–40 cm layer, as estimated from the average values of density and carbon concentration of the deposits (table 1), was about 3.8 kgc m-2. this value is larger than the amount of soil carbon contained in the surface soil layer (from o horizon to 10 cm depth of mineral soil) in the latter stage of succession of this area (nakatsubo et al. 2005). it is therefore concluded that old carbon distributed in the beach deposits represents a large fraction of the soil organic carbon in this area. the atp concentration has been used as an indicator of life in soil because exocellular atp has a half-life of less than 1 h (contin et al. 2001). the atp content was highest in the 0–2.5 cm layer (1.1 nmol g-1); it tended to decrease with soil depth (table 3). however, a low but significant amount of atp (0.07 nmol g-1) was detected even in the deepest layer (40–42.5 cm), which indicates that living microorganisms are present in the deeper layers (20–42.5 cm) of the raised beach deposit, although the content was significantly smaller than those in the shallow layers (0–12.5 cm) (mann-whitney u-test, p < 0.05). contin et al. (2001) reported a strong linear relationship between biomass c and atp over a wide range of concentrations, giving a mean atp concentration of 11 mmol atp (g biomass c)-1. assuming that this table 1 profile of carbon content in the raised beach deposit. layer (cm) density (g cm-3)a concentration (mg c g-1)b amount (mg cm-3)c total c organic c total c organic c 0–2.5 1.3 18.3 (1.5) 17.1 (1.1) 23.8 22.2 10–12.5 1.2 16.5 (0.7) 12.6 (1.4) 19.8 15.1 20–22.5 0.6 14.1 (0.2) 10.5 (0.7) 8.5 6.3 30–32.5 1.1 25.3 (–) 17.1 (–) 27.8 18.8 40–42.5 0.8 20.1 (–) 12.6 (–) 16.1 10.1 a means of 2–3 core samples. b means of three core samples are shown with se, except the 30–32.5 and 40–42.5 cm layers (n = 2). c density ¥ concentration. table 2 14c age (not calibrated) of soil organic carbon (soc) and seashell in the raised beach deposit. layer (cm) 14c age (yr bp) 0–2.5 soc 5 840 � 40 10–12.5 soc 11 440 � 50 20–22.5 soc 22 380 � 90 seashell 11 080 � 140 30–32.5 soc 35 890 � 240 40–42.5 soc 28 490 � 140 carbon and microbes in a high arctic raised beacht. nakatsubo et al. polar research 27 2008 23–27 © 2008 the authors 25 atp-biomass conversion factor is applicable to our site, the microbial biomass c in the deposit can be estimated from the atp concentration (table 3). the biomass c in the 0–2.5 cm layer (0.1 mg biomass c g-1) was about half of the value reported for surface soil (0–3 cm including organic soil) under the vegetation near our study site, as determined using the substrate-induced respiration method (bekku et al. 2004). the value in the deep layers of the deposit was estimated as about 0.01 mg biomass c g-1, which was less than 0.1% that of organic carbon (table 3). this fact indicates that microbial biomass c represents only a small fraction of soil organic c in the deposit. a small amount of microbial biomass carbon within a large pool of organic carbon indicates a low availability of the carbon source (insam & domsch 1988). the decreased fraction of biomass c to soil organic c with increasing depth suggests that organic carbon in the deep layer was less available to microorganisms than that in the shallow layers. however, the presence of microorganisms does not necessarily mean that they subsisted on old organic carbon in the deposit. it is also possible that they used ‘newly-fixed’ carbon carried by percolated water and/or cryoturbation. in addition, chemoautotrophic microorganisms and methane-oxidizing bacteria might be included in them. in fact, a recent study showed that considerable methane emission or absorption occurred in this area (adachi et al. 2006). further investigation including molecular-level 14c analysis of microorganisms (see petsch et al. 2001) is necessary to determine whether the microorganisms actually assimilate old organic carbon in the deposits. acknowledgements we thank the norwegian polar institute and the national institute of polar research for field logistics and support. we are also grateful to t. kobayashi (nies-terra) for ams operation and a. matsuda (nies) for sample preparation, and m. suzuki (jamstec) for sample preparation of ams analysis. this study is part of the “study on the past marine environmental changes” sponsored by the japan agency for marine–earth science and technology. this study was supported by a grant-in-aid for scientific research from the japan society for the promotion of science. references adachi m., ohtsuka t., nakatsubo t. & koizumi h. 2006. the methane flux along topographical gradients on a glacier foreland in the high arctic, ny-ålesund, svalbard. polar bioscience 20, 131–139. bekku y.s., nakatsubo t., kume a. & koizumi h. 2004. soil microbial biomass, respiration rate, and temperature dependence on a successional glacier foreland in ny-ålesund, svalbard. arctic, antarctic, and alpine research 36, 395–399. contin m., todd a. & brookes p.c. 2001. the atp concentration in the soil microbial biomass. soil biology and biochemistry 33, 701–704. dutta k., schuur e.a.g., neff j.c. & zimov s.a. 2006. potential carbon release from permafrost soils of northeastern siberia. global change biology 12, 2336–2351. forman s.l., mann, d.h. & miller g.h. 1987. late weichselian and holocene relative sea-level history of bröggerhalvöya, spitsbergen. quaterary research 27, 41–50. forman s.l. & miller g.h. 1984. time-dependent soil morphologies and pedogenic processes on raised beaches, bröggerhalvöya, spitsbergen, svalbard archipelago. arctic and alpine research 16, 381–394. insam h. & domsch k.h. 1988. relationship between soil organic carbon and microbial biomass on chronosequences of reclamation sites. microbial ecology 15, 177–188. jenkinson d.s. & oades j.m. 1979. a method for measuring adenosine triphosphate in soil. soil biology and biochemistry 11, 193–199. macnaughton s.j., stephen j.r., venosa a.d., davis g.a., chang y-j. & white d.c. 1999. microbial population changes during bioremediation of an experimental oil spill. applied and environmental microbiology 65, 3566–3574. michaelson g.j., ping c.l. & kimble j.m. 1996. carbon storage and distribution in tundra soils of arctic alaska, u.s.a. arctic and alpine research 28, 414–424. miller g.h. 1982. quaternary depositional episodes, western spitsbergen, norway: aminostratigraphy and glacial history. arctic and alpine research 14, 321–340. nakatsubo t., bekku y., kume a. & koizumi h. 1998. respiration of the belowground parts of vascular plants: its contribution to total soil respiration on a successional glacier foreland in ny-ålesund, svalbard. polar research 17, 53–59. nakatsubo t., bekku y.s., uchida m., muraoka h., kume a., ohtsuka t., masuzawa t., kanda h. & koizumi h. 2005. ecosystem development and carbon cycle on a glacier foreland in the high arctic, ny-ålesund, svalbard. journal of plant research 118, 173–179. table 3 atp concentration and biomass c in the raised beach deposit. layer (cm) atp concentrationa (nmol g-1) biomass cb (mg g-1) biomass/organic cc ¥100 (%) 0–2.5 1.10 0.10 0.59 10–12.5 0.74 0.07 0.53 20–22.5 0.10 0.01 0.08 30–32.5 0.07 0.01 0.04 40–42.5 0.07 0.01 0.05 a means of 2–3 core samples. b conversion factor; 11 mmol atp (g biomass c)-1. c mean value from table 1. carbon and microbes in a high arctic raised beach t. nakatsubo et al. polar research 27 2008 23–27 © 2008 the authors26 petsch s.t., eglinton t.i. & edward k.j. 2001. 14c-dead living biomass: evidence for microbial assimilation of ancient organic carbon during shale weathering. science 292, 1127–1131. roth k. & boike j. 2001. quantifying the thermal dynamics of a permafrost site near ny-ålesund, svalbard. water resources research 37, 2901–2914. sollins p., glassman c., paul e.a., swanston c., lajtha k., heil j.w. & elliott e.t. 1999. soil carbon and nitrogen. in g.p. robertson et al. (eds.): standard soil methods for long-term ecological research. pp. 89–105. new york: oxford university press. tanaka a., yoneda m., uchida m., uehiro t., shibata y. & morita, m. 2000. recent advances in c-14 measurement at nies-terra. nuclear instruments and methods in physics research-b 172, 107–111. uchida m., shibata y., ohkushi k., yoneda m., kawamura k. & morita m. 2005. age discrepancy between molecular biomarkers and calcareous foraminifera isolated from same horizons of northwest pacific sediments. chemical geology 218, 73–89. uchida m., shibata y., yoneda m., kobayashi t. & morita m. 2004. technical progress in ams microscale radiocarbon analysis. nuclear instruments and methods in physics research b beam interactions with materials and atoms 223–224, 313–317. yoneda m., shibata y., tanaka a., uehiro t., morita m., uchida m., kobayashi t., kobayashi c., suzuki r., miyamoto k., hancock b., dibden c. & edmonds j.s. 2004. ams 14c measurement and preparative techniques at nies-terra. nuclear instruments and methods in physics research b beam interactions with materials and atoms 223–224, 116–123. zimov s.a., davydov s.p., zimova g.m., davydova a.i., schuur e.a.g., dutta k. & chapin iii f.s. 2006. permafrost carbon: stock and decomposability of a globally significant carbon pool. geophysical research letters 33, l20502. carbon and microbes in a high arctic raised beacht. nakatsubo et al. polar research 27 2008 23–27 © 2008 the authors 27 climatic trend and the retreat and disintegration of ice shelves on the antarctic peninsula: an overview pedro skvarca, wolfgang rack, helmut rott & teresa ibarzibal y doningelo observations of the retreat and disintegration of ice shelves around the antarctic peninsula during the last three decades and associated changes in air temperature, measured at various meteorological stations on the antarctic peninsula, are reviewed. the climatically induced retreat of the northern larsen ice shelf on the east coast and of the wordie. george vi. and wilkins ice shelves on the west coast amounted to about 10 000 km’ since the mid1960s. a summary is presented on the recession history of the larsen ice shelf and on the collapse of those sections north of robertson island in early 1995. the area changes were derived from images of various satellites, dating back to a late 1963 image from the recently declassified us argon space missions. this photograph reveals a previously unknown, minor advance of the northern larsen ice shelf before 1975. during the period of retreat a consistent and pronounced warming trend was observed at the stations on both east and west coasts of the antarctic peninsula, but a major cause of the fast retreat and final collapse of the northernmost sections of the larsen ice shelf were several unusually warm summers. temperature records from the nearby station marambio show that a positive mean summer temperature was reached for the first time in 1992-93. recent observations indicate that the process of ice shelf disintegration is proceeding further south on both sides of the antarctic peninsula. p. skvarcn, h t i t u t o antartico argeritino, cerrito 1248. 1010 buenos aires, argentina; w. ruck & h. rott, institute for. meteorology arid geophysics. uiiit,ersity of innshruck, a 6 0 2 0 innshruck. austriu; t. 1bar:abul y doncingelo. servicio meteoroldgiro nacionnl, -75 de muyo 658, 1002 buenos aires, argentina. introduction few events in polar glaciology have attracted so much attention as the retreat of ice shelves on the antarctic peninsula, especially the disintegration and calving events which occurred in early 1995 on the larsen ice shelf. these events provide an excellent basis for studying the mechanisms of ice shelf disintegration but their environmental impact has still to be assessed. the analyses of temperature and sea ice data since the mid-1940s indicate a slight warming trend for antarctica and the surrounding oceans associated with the reduction in the sea ice extent (jacka & budd 1998). the increase of surface air temperatures is particularly evident in the region of the antarctic peninsula. king (1994) reports a significant warming for the west coast, which is of similar magnitude as the trend on the east coast (skvarca et al. 1998). furthermore, the longest instrumental temperature record available from antarctica (orcadas, south orkney islands) shows that the last two decades were the warmest in this century (hoffmann et al. 1997) and the record derived from an ice core from the dyer plateau reveals that these two decades were among the warmest since 1510 ad (thompson et al. 1994). twenty years ago mercer (1978) predicted the disintegration of ice shelves along the antarctic peninsula in response to a warming trend which may result from an enhanced greenhouse effect. since mercer’s statement several ice shelves in this region have retreated to some extent, some quite significantly. wordie ice shelf, located on the west coast, was the first to suffer major retreat (doake & vaughan 1991), while the northern larsen ice shelf on the east coast retreated steadily after 1975 (skvarca 1993; rott, skvarca et al. skvarca et nl. 1999: p o h r rescwch 18(?j, 151-157 151 1995) u n t i l two sections collapsed i n early 1995 (rott, skvarca et al. 1996; vaughan & doake 1996; rott, rack et al. 1998). the disintegration of ice shelves seems to be proceeding further south along the west coast. more recently, the wilkins ice shelf. reported previously to be i n rather stable condition (vaughan et al. 1993), has started to retreat at its northern margin (lucchitta & rosanova 1998). i n this paper we present an overview of ice shelf retreat and disintegration coinciding with a period of atmospheric warming. emphasis is on the larsen ice shelfdue to the magnitude and rapidity of changes and the possibility that this disintegra tion will continue further south, as concluded by doake et al. (1998) from model calculations on the stability of the ice shelf. atmospheric warming i n order to describe the recent climatic conditions on the antarctic peninsula, five stations located i n different climatic regimes have been selected (fig. i ) : a) orcadas (60.73" s, 44.73" w ) i n the south orkney islands, influenced by low pressure systems of the drake passage: b) esperanza (63.40. s, 57.00" w) at the northern tip of the i drake i passaae fig. 1. antarctic peninsula with locations of the stations and ice shelves discussed i n the text. antarctic peninsula; c) vernadsky (formerly fara day; 65.25' s, 64.27'' w) on the west coast and within the maritime climate affected by the sea ice extent i n bellingshausen sea; d) marambio (64.23' s, 56.62'' w; 198 m ad); and e) matienzo (64.98" s, 60.07' w). marambio and matienzo, representative of conditions on the larsen ice shelf, are located within a pseudo-continental climate which is controlled by the persistent pack ice conditions in the weddell sea. instrumental meteorological observations in antarctica started i n 1903 at the station orcadas, located on laurie island, south orkney islands. this is the longest temperature record i n antarc tica and i t shows a mean cooling trend of 0.4-c/ decade for the period 1904-1930, which was followed by a warming trend. hoffmann et al. (1997) noted that the difference i n decadal averages of air temperature between the decades 1921-1930 and 1981-1990, which was the warmest decade, amounted to 2.1"c. they also reported an increase of 1.o"c from 1971-1980 to 198 1-1990 at orcadas, esperanza and marambio. a strong correlation between south orkney islands and the stations of the antarctic peninsula was indicated by limbert (1974). recent analyses show higher correlations with esperanza and marambio on the east side than with vernadsky on the west coast (skvarca et al. 1998). the main reason for this is that the warmest period recorded at vernadsky, 1970-75. did not correspond to the warmest period recorded at the other stations (fig. 2). major climatic signals which affected the antarctic peninsula since 1960 are evident i n all temperature series, such as the low temperature in 1980, the maximum i n 1989 and the trend of above average temperatures after 1980 (fig. 2). the year 1989, which had the highest mean temperature on the west coast (morrison 1990), coincided with a minimum sea ice extent i n the bellingshausen sea (jacobs & comiso 1993). the coupling between temperatures and sea ice extent in this region was discussed by king (1994). for the station orcadas the linear fit shows a temperature increase of 0.026"c/year for the period 1930-1997, based on up-dated mean annual temperatures. this is a smaller trend than at vernadsky. which may be considered representa tive for the west coast, with 0.056'uyear (2.5"c total increase) during the period 1945-1990 (king 1994). however, considering the period 1971 1997 the trend at marambio of o.oso"c/year ( 1.4"c total increase) is comparable to that at 152 climatic trend and the retreat and disintegration of ice shelves on the antarctic peninsula 60 65 70 75 80 85 90 95 v -* esperanza i -8 60 65 70 75 80 85 90 95 4 l 4 marambio -10 -12 60 e 65 70 75 80 85 90 95 v vemadsky (faraday) 60 65 70 75 80 85 90 95 year (1900 +) f i g . 2. mean annual temperatures at t h e stations orcadas. esperanza and vernadsky (faraday) from 1960 to 1907, and at marambio froin 1070 to 1997, with %year moving means (after skvarca ct al. 1998). vernadsky. the increase a t esperanza on the northernmost tip of the peninsula was somewhat smaller (0.035uyear) than at marambio ( 1 97 i 1997), despite a strong correlation of the mean annual temperatures of both stations. skvarca et al. (1998) found that, according to the kendall-mann test, the trends are significant at 95% for the 1930 1997 orcadas series and for the summer tempera ture series of esperanza and marambio. i t can be concluded that the recent atmospheric warming has also affected the north-eastern region of the antarctic peninsula. retreat and disintegration of ice shelves on the antarctic peninsula only the decay of parts of the four largest ice shelves on the antarctic peninsula (fig. i ) is discussed below. miiller and jones ice shelves, the two northernmost ice shelves on the west coast, are also i n retreat; however they are quite small, and the bach ice shelf did not show changes in extent (vaughan & doake 1996). wordie ice shelf. affected by enhanced fracturing probably induced by atmospheric warming, was the first on which disintegration was observed at the end of the 1980s. it decreased by 13ookm’ in area between 1966 and 1989 (doake & vaughan 1991). the analysis of radar images showed that the retreat of this ice shelf has continued (vaughan 1993). for the northern margin of the george vi ice shelf, lucchitta & rosanova (1998) derived an area loss of 993 km’ from 1974 to 1995. for the wilkins ice shelf (also at its northern part) they measured a decrease of 1360 km’ between 1990 and 1995. however, the most remarkable changes and area loss during the last two decades were observed on the larsen ice shelf, the largest ice shelf on the antarctic peninsula. its northernmost limit is currently located at about 65” s. fig. 1 indicates different sections referred to by vaughan & doake (1996): larsen a (sobral peninsula to robertson island); larsen b (robertson island to jason peninsula); and larsen c (jason peninsula to ewing island). while no significant changes occurred between 1957 and 1986 i n its northern most section, which was confined within the prince gustav channel (fig. 3) (skvarca 1993), this section disappeared almost completely during 1986-1997, with a decrease in area of 837km’ during this period (rott, rack et al. 1998). from 1975 to 1986 the ice shelf sections between cape longing and seal nunataks (fig. 4) retreated by about 540 km’ (skvarca 1993), and from 1986 to 1997 by another 2624km’ as rott, rack et al. (1998) measured from time series of ers1/2 sar images. during the same period larsen b lost 2163 km2 in area, mainly due to the calving event in 1995 which gave rise to the iceberg a32 (fig. 3), 1720 km’ in area (rott, skvarca et al. 1996). a further decrease of about 110 km’, measured from a radarsat image of 25 april 1998, occurred as a result of calving in this section between february and march 1998, as revealed by noaa-avhrr images. to sum up, the larsen ice shelf has skvarca et 31. 1999: polar research / 8 ( 2 ) . 151-157 153 diminished by about 6300 km2 since late 1975. for the four ice shelves (wordie, george vi, wilkins and larsen) the total area lost by climatically induced retreat and disintegration during the observation periods (1966-1989, 1974-1995, 1990 95 and 1975-1998, respectively) amounted to around 10 000 km2. due to the rapidity of the event the disintegra tion of northernmost sections of the larsen ice shelf was remarkable. to illustrate the larsen disintegration and calving of 1995, two noaa avhrr images are shown (figs. 3a, b). these images provide an overview of the ice shelf before and after the event. the disintegration process north of seal nunataks and the calving between robertson island and jason peninsula were analysed i n detail by means of ers1 sar images (rott, skvarca et al. 1996), and were observed directly by personnel at the station matienzo, located on the larsen nunatak. they reported intense ice-quakes from 23 to 30 january, the main period of fracturing and disintegration. during this period intense westerly winds and unusually warm air temperatures were also observed. the satellite images show the presence of meltwater features on the ice shelf, which is typical for warm summers; 1994-95 was the warmest summer of the 28 year record of the station marambio (rott. skvarca et al. 1996; skvarca et al. 1998). fig. 4 presents the time series of retreat for larsen inlet and larsen a. with the exception of one date (23 october 1994), the frontal positions shown were derived from satellite imagery extending back to 1963. the general retreat of the ice front from 1975 onwards and the recent collapse have already have been described in detail by skvarca (1993). rott, skvarca et al. (1995, 1996), vaughan & doake (1996) and rott, rack et al. (1998). this information is presented here i n order to show the complete sequence of the temporal and spatial changes of this ice shelf section. after an advance between 1963 and 1975. observed by means of recently declasified us military satellite data (argon), this section re f i g . 3. noaa-12 avhrr (advanced very high resolution radiometer) images of the northern antarctic peninsula showing all sections of the larsen ice shelf which were affected by the 1995 events. a: 9 january 1995, prior to the events. b: 23 february 1995, after the events. this image shows the ice shelf hetween sobra1 peninsula and rohertson island fragmented into thousands of small icebergs which, together with ice debris. formed a large plume extending 200 km towards seymour island. the iceherg a32 had separated parallel to the ice edge due to the strong north-westerly winds (rott, skvarca et al. 1996). the abundance of meltwater on the ice shelf surface (dark patches) resulting from the exceptionally warm summer 199-1-95 (fig. 5) can be observed on both images to extend well south of robertson island. 154 climatic trend and t h e retreat a n d disintegration of ice shelves on t h e antarctic peninsula f i g . 4. section of the kosmos kate-200 photograph taken on 3 october 1975 (skvarca 1993), showing superimposed the ice front positions (numbers in black boxes) i n different yearc. 1 : the ice front position indicated by dashed line is new information and corresponds to 30 august 1963 argon photograph (frame i 15, mission 9058a). recently declassified by us: 2: 3 october 1975: 3: 4 november 1978; 4: 20 february 1979 5 : 1 march 1980; 6: 5 november 1989 (after skvarca 1993): 7: 8 december 1992; 8: 12 january 1993; 9: 16 february 1993: 10: 23 october 1944: i i : 25 january 1995; 12: 28 january 1995; 13: 30 january 1995 (after rott, skvarca et al. 1996); 14: 8 march 1995; 15: 2 march 1497: 16: july, 1997 (after rott, rack et al. 1998). the front positions after 1992 were derived from ers-sar, except for position 10, surveyed with gps. the positions prior to 1992 correspond to landsat tm (positions 5 and 6), landsat mss (positions 3 and 4), argon ( 1 ) arid kosnios kate-200 (2). (after skvarca 1993; published by courtesy of sojuzkarta.) skvarca et a]. 1999: polar research 18(?), 151-157 155 treated since 1975. the advance followed a cold period which affected all of the antarctic penin sula between 1956 and 1959 (limbert 1974). discussion mercer (1978) assumed the 0°c january air temperature isotherm as the climatic limit for the existence of ice shelves, whereas according to reynolds (1981) the critical limit is close to the 5'c mean annual isotherm at sea level. vaughan & doake (1996) discussed the migration of the northern limit of ice shelf viability in response to atmospheric warming, based on the mean annual temperature map of the antarctic peninsula of reynolds (1981) and taking into account the 2.5'c air temperature increase since 1945 (king 1994). they suggested that a further increase of 1 c might trigger the decay of the george vi and wilkins ice shelves. according to lucchitta & rosanova (1998), the northern margins of both ice shelves are already retreating significantly. in the case of the larsen ice shelf the southward shift of the climatic limit towards robertson island has been mentioned by skvarca (1994), based on the accelerated rate of retreat north of the seal nunataks. it has been shown (skvarca et al. 1998) that a warming trend similar to that occurring on the west coast is also affecting the region of the northern larsen ice shelf, which is responsible for the disintegration of this ice shelf. the observed southward shift of the northern boundary of the larsen ice shelf to its present position at seal nunataks (fig. 4) could not be expected from the isotherms shown by reynolds. even if the warm ing trend of marambio is taken into account. possibly the temperature map, compiled more than 20 years ago, is inaccurate due to lack of data from this region of strong gradients of surface air temperature. t o understand the ongoing changes on the antarctic peninsula. it will, however, be important to know in detail the present climatic conditions, as well as the pattern of temporal changes during the last decades. continuous meteorological observations are not available for the larsen ice shelf. for the station matienzo on larsen nunatak temperature observa tions throughout the year are available only from 1961 to 1972. after that the observations con tinued only in summer and with some interruptions until 1985. recent work (skvarca et al. 1998) has shown a good correlation (correlation coefficient r = 0.90) between the summer temperatures of matienzo and marambio, which indicates that marambio is representative of summer conditions on the northern larsen ice shelf. the amount of surface meltwater on ice shelves plays an important role in the fracturing process and disintegration (doake & vaughan 1991). ridley (1993) concluded from the analysis of spaceborne passive microwave data of the period 1978 to 1991 that the duration of the summer melt season on the ice shelves of the antarctic peninsula has increased slightly during this period, at a rate of about 1 daylyear. these observations are in agreement with the observations of in creased surface melt in sar images which are available from ers1 and ers-2 since 1992. the pronounced increase of mean summer tempera tures at marambio is also an indicator of more intense surface melt during recent years. the linear regression of time series of mean summer temperatures at esperanza and marambio (fig. 5 ) show a pronounced trend at both stations. how ever, as mentioned above, of particular importance for the larsen ice shelf is the trend of o.o74"c/ year observed at marambio between the summers 1970/71 and 1997198. the observed decrease in net surface accumulation on the northern larsen ice shelf was probably caused by the increasing melt rates due to this warming trend: at the station marambio the mean summer temperatures in the 1990s were positive twice and at esperanza very close to or above 0°c from summer 1973-74 to the present (fig. 5 ) . -+.. esperanza -+marambio --&matienzo t . . . . . . . . . 4 . . . . . . . . . i . . . . . . . . . 8 . . . . . . j we1 7w1 80181 9391 year (1 900 +) fig. s. mean summer temperatures at maramhio, esperanza and matienzo with least-square fits for marambio and esperanza (reprinted from the aiznuls ofgluciology with permission of the international glaciological society: skvarca et al. 1998). 156 climatic trend and the retreat and disintegration of ice shelves on the antarctic peninsula during the recession phase of the northern larsen ice shelf(fig. 4) the major events of retreat and the final collapse coincided with periods of temperatures which were clearly above the average. for instance, the disintegration of the larsen inlet took place during the period 1987-89, which shows two peaks in mean summer tem peratures (fig. 5 ) . the next major change i n this region was the decrease of 2 0 9 k m 2 i n area of larsen a (rott, skvarca et al. 1995) indicated by ice front positions 7 and 9 (fig. 4), which took place in the warm summer 1992-93 when the mean summer temperature at marambio was positive for the first time. finally, the collapse of larsen a, with a decrease of 1640 km’ between november 1994 and march 1995, was associated with the highest summer temperature (+0.6 c i of the record at marambio. the main disintegration took place within just two days (january 28-30), when 856 km2 of the ice shelf broke off in the form of comparatively small icebergs and drifted away (rott, skvarca et al. 1996). conclusions the observed retreat and disintegration of the ice shelves around the antarctic peninsula can be taken as a clear indicator of regional climatic change. if the warming trend of the last two decades continues, the disintegration will very likely proceed further south on both sides of the peninsula. this is also suggested by the recent observations of retreat on the wilkins and larsen ice shelves. the estimated total decrease i n the area of the ice shelves since 1966/1975 amounts to about 1 0 0 0 0 k m 2 , 63% of which refer to the larsen ice shelf. the impact of these changes on the regional oceanic and atmospheric environment has still to be assessed. as a new coastline has been exposed due to the ice shelf decay, the inland grounded ice should be monitored in detail to detect any further retreat as a potential contributor to a rise in sea level. aek,~orr~le.d~enlrrits. thanks are due to p. alagia and j . l. fornaro for aasiatance in producing the figures. temperature.. ot argentine stations were provided by servicio meteorokigico nacional. fuerza akrea argentina. the vernadsky (faraday) data are from the british antarctic survey data set. this work is a contribution to the larsen ice shelf project of instituto antirtico argentino, direccidn nacional del antirtico. and to austrian science fund (fwf) project no. 12923 ceo. references doake. c. s . m. & vaughan. d. g. 1991: rapid disintegration of the wordie ice shelf in response to atmospheric warming. nrrrirw 350. 328-330. doahe. c. s . m.. con, h. f. j.. rott. h.. skvarca, p. & young. n. w. 1998: breakup and conditions for stability of the northern larsen ice shelf, antarctica. nutiwe 391, 778-780. hoffmann, j. a. j.. nurez, s. e. & vargas. w . m. 1997: temperature, humidity and precipitation variations in a gentina and the adjacent auh-antarctic region during the present century. metrorol. z. n . f. 6 , 3-1 i . jacka. t. h. 8: budd, w. f. 1998: detection of temperature and sea-ice-extent changes in the antarctic and southern ocean. 1949-96. ann. glnciol. 27. 553-559. jacobs, s . s . & comiso. j. c. 1993: a recent sea-ice retreat west of the antarctic peninsula. gropliys. res. l e f t . 2 0 ( i z ) , 1 171 1171. king. j . c. 1994: recent climate variability in the vicinity of the antarctic peninsula. inr. j . climutol. 14, 357-369. limhert, d. w. s. 1974: variations i n the mean annual temperature for the antarctic peninsula, 1904-72. poli7r /?word 17(108), 303-306. lucchitta, b. k. & rosanova. c. e. 1998: retreat of northern margins of george v i and wilkins ice shelves, antarctic peninsula. ann. g/ucifjl. 27, 41-46. mercer, j . h. 1978: west antarctic ice sheet and co2 greenhouse effect: a threat of disaster. nurure 271. 321-325. morriqon. s . j. 1990: warmest year on record on the antarctic peninaula. wenrher 45. 1-3 1-232. reynolds. j. m. 1981: the distribution of mean annual temperatures in the antarctic peninsula. br. aiirurcr. s ~ i n ~ . btill. 53. 123-133. ridley, j . 1993: surface melting on antarctic peninsula ice shelves detected hy passive microwave sensors. g ~ ~ p l i y . ~ . res. lett. 20(12), 2639-2642. rott, h., skvarca. p. & nagler, t. 1995: recent changes of laraen ice shelf, antarctic peninsula, unveiled by ers-i. r e ~ ~ i s t a selper i i ( ] 2 ) . 46-50. rott. h., skvarca, p. & nagler, t. 1996: rapid collapse of northern larsen ice shelf. antarctica. science 271. 788-792. rott, h., rack, w.. nagler. t. & skvarca, p. 1998: climatically induced retreat and collapse of northern larsen ice shelf. antarctic peninsula. a m . gluciol. 27, 86-92. skvarca, p. 1993: fast recession of the northern larsen ice shelf monitored by space imagea. ann. glnciol. 17, 317-321. skvarca, p. 1994: changes and surface features of the larsen ice shelf. antarctica, derived from the landsat and kosmos mosaics. a m . glaciol. 20. 6-12. skvarca. p.. rack. w., rott, h. & iharzihal y doningelo. t. 1998: evidence of recent climatic warming on the eastern antarctic peninsula. ann. glaciol. 27. 6 2 8 4 3 2 . thompson, l. g.. peel. d. a,, mosley-thompson, e.. mulvaney. r.. dai, j., lin. p. n., davia. m. e. & raymond, c. f. 1994: climate since ad 1510 on dyer plateau. antarctic peninsula: evidence for recent climate change. atin. gliiciol. 20, 4 2 w 2 6 . vaughan, d. g. 1993: implications of the hrezk-up of wordie ice shelf. antarctica for sea level. anfurcr. sci. 5 ( 4 ) , 1 0 3 4 0 8 . vaughan, d. g., mantripp. d. r., severs, j. & doake. c. s. m. 1993: a synthesis of remote sensing data on wilkins ice shelf, antarctica. ann. glnciol. 17, 21 1-218. vaughan. d. g. & doake, c. s. m. 1996: recent atmospheric warming and retreat of ice shelves on the antarctic peninsula. nurure 37y. 328-33 i . skvarca et al. 1999: polar reseorch 18(2). 151-157 157 pleistocene stratigraphy of kongsfj ordhallet, spitsbergen, s v a1 b ar d michael houmark-nielsen and w e n d funder houmark-nielsen, m. & funder. s . 1999: pleistocene stratigraphy of kongsfjordhallet, spitsbergen, svalbard. polar reseurch i r ( 1 ) . 3 9 4 9 . open sections along kongsfjordhallet. the north-western coast of kongsfjorden. svalbard, exhibit marine and glacigenic sediments of early to late pleistocene age. glaciation, deglaciation and subsequent isostatic rebound caused the formation of three sedimentary successions (a. b and c) that comprise till grading upward into glaciomarine mud. followed by shell-bearing sand, and finally littoral sand and gravel. six major lithostratigraphic units are recognized. succession c comprises units 1 and 2, which were deposited during an early pleistocene glaciation, followed by deglaciation and subsequent beach progradation. succession b is divisible into units 3 and 4 and reflects glaciation and eventual emergence as a result of isostatic response. the youngest succession (a) comprises units 5 and 6, and reflects fiord glaciation followed by a regression during an early weichselian glaciation-deglaciation episode. ice-free conditions may have prevailed until the late weichselian, when a glaciation, confined to the fiord trough, covered parts of kongsfjordhallet. deglaciation and isostatic rebound are recorded by holocene marine terraces up to ca 40 m a.s.1. marine and glacial events from kongsfjordhallet are compared with stratigraphic evidence from adjacent regions and it is suggested that the late weichselian ice configuration was of a more restricted nature than proposed by previous authors. glaciers draining through the larger fiord troughs reached the shelf break, while at the same time other parts of western svalbard could have experienced restricted glaciation. m . hounzark-niel.sen, geologicul institute, universih of copenhagen, 0stervoldgade 10, dk1350, copenhugen, denmark; s . fitnder, geological museum, universin. of copenhagen. 0stervoldgade 5-7, dk-1350. copenhagen. denmurk. introduction the present study deals with the pleistocene stratigraphy and. i n particular, the weichselian glaciation history of kongsfjordhallet, svalbard. special attention is paid to the question of terrestrial evidence for major late weichselian ice cover in the kongsfjorden region. the late pleistocene stratigraphy from kongsfjordhallet is compared with data from three other sites along the western coast of spitsbergen, between isfjor den and kongsfjorden. previously unknown early-middle pleistocene deposits and their rich marine molluscan faunas from kongsfjordhallet are briefly described. these will be dealt with i n more detail in a later publication. field work was carried out in 1993 under the ponam project (polar north atlantic margins: late cenozoic evolution), as reported by houmark-nielsen et al. (1993). additional sampling was made during shorter visits in 1996 and 1997. previous work stratigraphic studies from a locality east of kapp guissez (boulton 1979) indicated three cycles of emergence related to glaciation and subsequent marine deposition during isostatic rebound. the youngest cycle was “c-dated to the late weich selian-holocene transition, and related to the retreat of a local glacier, which, according to boulton (1979), did not extend to the locality he investigated. high marine terraces at 66 m above present sea level were correlated with similar high marine terraces with ’‘c ages of around 40 ky from br@ggerhalv@ya, and ascribed to isostatic rebound after an earlier glaciation. the relative sea level changes and glacial history from northern most pnns karls forland (boulton 1979) show a close resemblance to events from the kongsfjor den localities. boulton concluded that a major glaciation reached the outer shelf before 40 kya. late weichselian glaciation was local, and 40 m . hournark-nielsen & s. funder table 1 . radiocarbon dates. kongsfjordhallet. c age i ?c i4 altitude unit loc. (m a d . ) sample no. type lab id wy) %o pdb 6 1312a 50 100217 shell: u aar1360 > 37 +1.6 5 1301 78 100222b shell: ha aar309i >3i + 1 . 1 5 1301 29 100222a shell: mc* aar3090 22.5 f 0.3 + i 5 1301 29 100222c shell: ha* aar3809** > 55 +1.3 5 1301 29 110222c shell: ha* aar3809*** 35 +1.3 5 1305a 21 9562 i shell: ab aar i358 > 53 + i 2 5 1312b 38 1001-18 shell: ha* aar1359 > 5 i +2.1 u = unidentified shell fragment, ab = asrarre boredis. ha = hinrella nrcricn. mc = macoinci calcaren. * = in sku shells. ** = inner fraction. *** = outer fraction. possibly no more extensive than at present or during the little ice age. lehman & forman (1992) described beach gravels considerably above the supposed late weichselian-holocene marine limit from kongsf jordhallet. these beach sediments contain frag ments of hiatella arcticu with amino acid ratios similar to those characterizing episode c of braggerhalvaya (miller et al. 1989). it was noted that the raised marine deposits show no evidence of glacier overriding; however, a lateral moraine, trending almost parallel to the coast, cross-cuts the older marine sediments. the moraine was con sidered to be of late weichselian age, although it might represent only a minimum extent of this ice cover (lehman & forman 1992). it was argued that the late weichselian-holocene marine limit descends towards the west from approximately 42 m a.s.1. to about 36 m a.s.1. along kongsfjord hallet. this ocean-ward tilting was supposedly caused by isostatic recovery from a late weich selian glacier occupying kongsfjorden. cores containing till overlain by shell-bearing glacio marine diamicton (dated at ca. 14-12 kya in the trough outside kongsfjorden) is taken as evidence for late weichselian glacial cover and subsequent deglaciation from the shelf adjacent to the mouth of the fiord (landvik et al. 1998). methods open sections were logged for lithostratigraphic classification and interpretation of sediment gen esis, while marine molluscan faunas were studied to aid palaeoecological interpretations. total alle : ile ratios are used for inter-site correlation and comparison with amino episodes at sites in the kongsfjorden region. six samples of marine mollusc shells (hiatella arctica. macorna calcarecr and astarte borealis) were ''c dated by the ams method (table 1). two sediment samples that have been luminescence-dated using the single aliquot regeneration protocol on sand-sized quartz grains (murray & roberts 1998; murray & mejdahl 1999) are presented in table 2 . twelve samples of marine mollusc shells (myci truncata and hiatella arctica) have been analysed for amino acid epimerization (aile : ile) in the hydrolysed (total) and free fractions using standard procedures described by sejrup (1990) (table 3). geomorphology kongsfjordhallet is a 1-2km wide and 6-7km long strandflat at the north-western shore of kongsfjorden (fig. 1). it rises from about 4 0 m a.s.1. at the coast to ca. 1 0 0 m at the foot of the mountain. unconsolidated quaternary sediments unconformably overlie the strongly folded and metamorphosed hecla hoek fm (hjelle & laur itzen 1982) and consist of 15-35 m thick deposits of interfingering till, glaciomarine diamictons, littoral sand and gravel, and smaller quantities of tuble 2. luminescence dates succession a, kongsfjordhallet. a it i t ude age unit loc. (in a d . ) sample lab id (ky) ~~ 6 1309 27 100107 r 951009 75 2 10 5 1301 31 100213 r951010 91 2 9 pleistocene strotigrqdiy of kongsfjordhallet, spitsbergen, svulbard 4 1 tuhk 3. amino acid nlle/lle ratios in shells* from kongsfjordhallet. altitude total hydrolyaate free fraction unit loc. ( m a . ~ l . ) sample id avg** f avg"* f s 5 5 5 5 5 s 2 1 2 2 7 1301 130521 i30sa i307 i309 1309 1312b 1303 i304 1305a i306 1306 28 20 21 19 27 27 39 16 10 10 9 9 100207 bill3244 lool0x 8313700 9562 i ha1303 1 100102 ba13196 95623 ra13319 y5622 i3a13 195 loo2lh ba13201 95625 ba13032 100203 ba13197 y561') bd13030 100205 13a13 199 10020.5 ba13198 0.078 f 0.001 0.03 ? 0.001 0.227 f 0.01 i 0.036 f 0.001 0.026 f 0.003 0.030 f 0.001 0.030 f 0.000 0.239 f 0.01 1 0.165 f 0.008 0.138 f 0.007 0.238 f 0.004 0.035 f 0.001 0.13s f 0.000 0.207 f 0.017 0.765 f 0.01 1 0.249 f 0.01 3 0.223 f 0.002 0.164 f 0.007 0.173 f 0.006 0.789 t 0.021 0.640 f 0.030 0.655 f 0.013 0.810 f 0.016 0.805 2 0.013 *all ?hells are m w rruncrr~u except ba13 199 (hinrrllu i r r u i u r ) . **averagr of two measurements in each of two valves alluvial fan and slope deposits. examined sections are located between tonsneset and kapp guissez, about 10-15 km north-west of ny-alesund. a stony and boulder-rich veneer with far travelled erratics laps onto the mountain slopes u p to 120 m a d . south-west of kappfjellet, and u p i halvaya p 25,krr 78" 25" spitsbergen fig. 1. key and location map of kongsfjordhallet showing land. wa and inodern glaciers. to more than 200 m a d . north of t ~ n s n e s e t . these levels are assumed to indicate the maximum extension of glaciers moving through the fiord (fig. 2). patches of glacigenic sediments in hummocky and elongated ridges rise from about 40 ni a.s.1. south of kapfjellet to more than 150 m a.s.1. north of t@nsneset (fig. 2), and constitute an apparently fresh and undisturbed lateral moraine which marks the extent of the youngest ice cover i n the area. raised beaches older than the late weichselian and overlying glacial deposits are found up to 80 m a.s.1. they cover major parts of the strandflat and build up the youngest littoral deposits exposed in most cliff sections and inland exposures. scattered rocks and boulders, but no till, are found on the raised marine terraces inside the moraine. an erosional scarp in the raised marine terraces north of t ~ n s n e s e t suggests that the late weich selian-early holocene marine limit did not exceed 4 3 m a.s.1. a slightly younger, marked scarp cut into the older marine deposits at about 30 m a.s.1. is found in the western and eastern end of the cliff exposures. although not dealt with in the present investigation, we accept the extent of the late weichselian-holocene marine limit given by lehman & forman (1992), which suggests a westward decline of about 1 m/km. the youngest geomorphical features on the kongsfjordhallet are represented by the proposed neo-glacial phenomena shown in fig. 2. gullies and young meltwater channels have cut through the quaternary cover into the bedrock as a result of the relative sea level lowering and melting of (sub-) recent glaciers in the hinterland. 42 m. hournark-nielsen & s, funder f i g . 2. geomorphic features along the coast of kongsfjordhallet based on reconnaissance and studies of aerial photograph s90 6768 (norsk polarinstitutt 1990). the late weichselian-holocene marine limit is not distinguished from older marine limits. numbers indicate positions of investigated sites (1301-1312). stratigraphy ten sites located along the coastal cliffs and two sites about 0.5 km inland were investigated (fig. 2, points 1-9 & 12; fig. 3, 1301-1312), and used to compile three composite facies successions (a, b, c) i n which six lithostratigraphic units have been recognized. some successions are simple coarsen ing upwards sequences while others may be composite, or even chaotic in nature. in fig. 3 we have distinguished four major facies comprised of diamictons (either deposited as till or as ice proximal glaciomarine sediments) which indicate successive glaciations and deglaciations. it should be noted that the format of fig. 3 does not allow distinction between closely related facies such as till and glaciomarine diamictons. mud refers to a spectrum of clast-bearing to clast-free fine sedi ments deposited from ice-rafting and suspension in an ice-distal setting beneath the wave-base. sand and gravel represent sublittoral and littoral deposi tion under high energy conditions. succession c the oldest facies succession is preserved in a bedrock depression in the central parts of the cliff exposures (fig. 3 ) , and comprises units 1 and 2. these represent one or several glacial cycles. unit 1 consists of at least 10 m of red to black, dark-banded, matrix-supported diamicton which contains striated stones and shell fragments. it generally rests directly on bedrock. the lower part of the diamicton is interpreted as a till, deposited from glacier ice which moved down either from the mountains of the hinterland, or through the fiord. the upper 2-3m grade into clast-poor silty diamicton and mud with drop stones and lenses of fine sand. these have a characteristic reddish and chocolate brown col our. the sediment contains shells in life position, and was deposited under distal glaciomarine conditions. at site 1305, the fauna contains a high proportion of m y a truncata and hiatella arctica in life position in their burrows, and among the minor constituents, the extinct cyrto &aria angusfu. two metres of unsorted, dense, pebbly, silty sand is found i n unit 1 at site 1303, with a marine fauna comparable to that of unit 2. the fauna of unit i is dominated by h . arctica and astarte borealis while the characteristic c. angustu is also present, and the close resem blance to the fauna of unit 2 indicates that they may be quasi-contemporaneous. the lower part of unit 2 is more than 10 m thick. pleistocene stratigraphy of kongsfjordhallet, spitsbergen, svalbard 43 45 rn 40 35 30 25 20 15 10 5 if 5 eg diamicton mud 0 sand gravel +glacier movement (till fabric) fig. 3. lithoatratigraphic logs and correlation between sites along the coast of kongsfjordhallet. numbers indicate stratigraphic units (1-6). letters refer to sedimentary successions (a. b and c') and consists of well-sorted sand with pebbles and shell horizons. it overlies the muddy silt of u n i t 1 with a gradational transition, and is sharply and erosionally limited upwards by coarse, clast supported gravel or muddy diamicton. it is characterized by an apparent lack of well-defined sedimentary structures (apart from crude sub horizontal bedding). another conspicuous feature is the richness and diversity of marine bivalve shells, often in life position. preliminary results were published by funder (1993) and a detailed study is under way. dominant species consist of c. angustu (extinct), large serripes groenlundicus, asturte morztagiri and macornu culcurea, while very thick m . tritncuta and a. boreulis are locally common. among the many minor constituents are m y t i l u s edulis and seinibalarziis balarioiiies. the upper part of unit 2 unconformably overlies the shell-bearing sand with an erosional contact. i t is composed of sandy gravel with abundant well rounded boulder-sized clasts at the base, fining upwards into pebbly sand at site 1304. these sediments probably originated from alluvial fans deposited under low sea level conditions, which were later reworked by waves as sea level rose during glacio-isostatic loading. amino acid ratios from five samples in unit 2 cluster in two groups, with ratios of 0.138-0.165 and 0.235-0.239 (table 3). succession b the middle succession comprises units 3 4 and is built up of a number of facies consisting of coarse and occasionally boulder-rich gravel, shell-bear ing sand and muddy matrix-supported diamicton (fig. 3). unit 3 comprises metre-sized clasts of shell bearing sand and large blocks of crystalline rocks embedded i n matrix-supported diamicton, and crudely bedded gravel all deposited by a glacier which must have been capable of reworking marine sediments from the fiord. other parts of unit 3 consist of shelly, interfingering lenses and beds of sand, gravel and reddish muddy matrix supported diamicton. the diamicton were depos ited as subaqueous debris flows and fallout from suspension, and material dropped from ice in a 44 m. houniark-nielsen & s. funder glaciomarine environment under conditions of relatively high sea level. unit 4 includes stony and sandy clast-supported gravel more than 10 m in thickness, with lenses of sorted coarse sand and fine gravel. it represents deposition under littoral environments at progressively lower relative sea levels. faulting and sliding a phase of faulting and sliding took place prior to, and possibly a150 during deposition of unit 5 . along the coast, units 1 4 (including the lower part of unit 5 at site 130%) dip 15-30” north eastward. this was most probably caused by rotational sliding and faulting of unconsolidated sediments along the cliffs, where the muddy facies of unit 1 acted a5 the surface of dbcollement. the presence of tilted sedimentary packages suggests the removal of support, by melting of glacier ice in the fiord, and subsequent lowering of sea level, which allowed blocks to slide toward the fiord. succession a the upper facies succession is composed of units 5 and 6 (fig. 3). unit 5 is a reddish to grey. matrix supported diamicton with striated clasts and boulders from the inner fiord zone. it is generally less than 2 m thick. fabric analyses of long-axis orientations at site 1301 and 1302 show a significant nw-se orientation, with a preferred dip toward the south-east. the diamicton is interpreted as a till, deposited by a glacier moving north-west toward the fiord mouth. the till contains shell fragments of the robust m . rruncata and h. arctica. at site 1309, the fragments also include the subarctic calamys islandica. a single battered specimen of lacuna viticfa was found on the cliff surface. the latter species is now absent from svalbard, but is known from the underlying cyrtodaria beds (also containing c. islandica) from which, it is suggested, the fauna is reworked. at site 1305a. a lens of sand incorporated into muddy diamicton, contains abundant, but frag mented, shells from a diverse fauna dominated by m. truncata, macoma calcarea and a. borealis. minor constituents are a. montagui, h. arcticti. serripes groenlandicus, balatius creiicitus and s. halanoides. fragments of cyrtoduria atigusra are also common, and the fauna is very similar to that of the underlying unit 2. the possibility of reworking from unit 2 is supported by amino acid ratios of 0.227, which are similar to those of unit 2 (table 3). stones with preserved foot-plates of balatius crenatus and crusts of lithothainnioti show that the sediments have been reworked as one allochthonous unit. upwards, the diamicton changes into a shell bearing mud containing m . truncata, paired shells of h. arctica and macoma calcarea together with ice-rafted pebbles. this facies of unit 5 was most probably deposited in a glaciomarine environment. at sites 1305 and 1309, sandy lenses contain a sublittoral arctic fauna dominated by macoma calcarea and serripes groenlandicus. at inland site 1312 (up to 4 0 m a.s.l.), unit 5 comprises shell-bearing marine mud with a sparse fauna consisting of h. arcfica in life position and fragments of m . rruizcata, covered by littoral gravels (fig. 3). deposits beneath the mud (unit 4) have suffered reverse faulting from the south and south-east caused by an overriding glacier in the fiord. unit 6 is less than 10 m thick. it is composed of muddy sand with burrows, overlain by bedded sand, and frequently overlain unconformably by clast-supported stony gravel. all facies contain shell fragments. along the cliff sections, the gravel is found at maximum altitudes between 35 and 4 0 m a.s.l., while it reaches up to at least 50 m at inland sites. the sediments are interpreted as sublittoral sand and mud, overlain by littoral gravels and beach deposits, which were laid down regressively during glacio-isostatic rebound. at cliff sites, the very top of unit 6 could have been reworked under the highest relative sea level stand of the late weichselian-holocene. successions a, b and c represent at least three emergence cycles showing upward coarsening sedimentary sequences suggesting repeated gla ciation, followed by glaciomarine and littoral sedimentation during subsequent isostatic re bound. palaeomagnetic measurements taken in 1994 from the upper part of unit 1 at site 1305a show reversed polarity (r. l0vlie and j. mangerud pers. comm. 1997). in combination with the high amino acid ratios, this suggests an age in the matuyama chron of 0.74-2.48 my for succession c. this is i n agreement with the molluscan fauna, which could pleistocerie ,stratigraphy of korigsfiordhallet, spitsbergen, svalburd 45 indicate an age of ca 1 my or more (funder 1993). it also confirms the assumption of miller (1982). based on amino acid stratigraphy. that very old pleistocene marine sediments are present along the south coast of kongsfjorden. from succession b we have no age-suggestive faunas. dates, or amino acid values. the sediments reflect a regional glaciation followed by ice-free conditions which caused a lowering of the relative sea level, possibly to present day levels. glacio tectonic structures in the upper part of succession b indicate subsequent glaciation. succession a is characterized by aile : ile values of 0.026-0.036 indicating that the entire marine sequence i n this succession belongs to the sanie depositional episode (table 3). radiocarbon dating of shells indicates deposition before 40 kya (table 1). one sample of paired shells of macon7a crilcareci is dated to 22.4 kya (sample aar 3090). however, this sample was so under sized that i t was not possible to perform the usual acid etching of the outer 25% of the shell to remove possible surface contamination. although its age is technically finite. careful examination of sample aar-3809 from the same bed at site 1301 suggests a much older age (j. heinemeier pers. comm. 1998). with aar-3809, paired shells of h . circticci were dated in two fractions. the first fraction of co?, evolved from the shell during acidification (i.e. the outer part of the shell), yielded an apparent finite age of 36 ky, whereas the second fraction (i.e. the fraction remaining after surface etching) yielded a non-finite age of >45 ky. this difference indicates that the ;it .sim surface contamination of shells, at least from this site, is a serious source of error. luminescence dating of succession a indicates deposition between 91 k 9 kya and 7 5 f 10 k y a (table 2 ) . and confirms the non-finite radiocarbon ages of it7 siru shells. since the ages overlap with one standard deviation, and only two dates are available. our data indicate that a major glacier passed through kongsfjorden during the early weichselian. some time between 100 kya and 65 kya. i t was followed by an ice-free interval with isostatic recovery and deposition of littoral sediments and beach gravel. the latest ice advance. which deposited boulders and formed the lateral moraine covering unit 6, has not been dated directly. however, it is probably consider ably younger than unit 6, and could be of late weichselian age. as proposed by lehnian & fornian ( 1992). correlation and weichselian glacial history regarding br@ggerhalv@ya, miller et al. (1989) and forman (1989) advocated that only regional glaciation occurred during the early weichselian. and that stratigraphic evidence for later glaciation was missing. however. raised holocene shorelines and beach deposits indicate younger weichselian glaciation in the region. succession a (units 5 and 6) amino acid values correspond to those of "episode b" on nearby b r ~ g g e r h a l v a y a (fig. 4). these have been given an early to middle weichselian age of 80 and 7 0 ky (miller et al. 1989). which is comparable to those of our succession a. the deposits most probably experi enced the same thermal history. and we correlate the tills beneath the marine deposits with each other. indicating that they represent the same regional early weichselian glaciation. this age is supported by the presence of supposed eemian sub-till deposits at br#ggerhalv@ya. glaciomarine and sublittoral deposits overlying till at poolepyn ten, prins karls forland, have also been correlated with episode b ( a n d e r s o n et al. 1999). i4c dates of kelp show non-finite ages ( > 4 9 ky), whereas amino acid ratios in these deposits are consider ably lower than at br@ggerhalv@ya and kongsf jordhallet and cannot be distinguished from values found i n "c-dated late weichselian-holocene marine deposits (fig. 4). assuming equal duration of late weichselian-holocene submergence be low sea level at all localities, this may account for two-thirds of the epimerization found in episode b and succession a sediments. a late weichselian glacier, which did not reach prim karls forland. could account for the higher epimerization at braggerhalvaya and kongsfjorden. the glacial maximum (fig. 2) is thought to depict the distribution of the early weichselian glaciation as the bouldery veneer indicating this maximum is covered by unit 6 gravel from 8 0 in a.s.1. and below. the lateral moraine cross-cutting kongsfjordhallet marks the limit of an ice advance during the late weichselian glaciation, but whether it represents the maximum extension, o r a readvance, cannot be judged from our data. the scattered rocks and boulders found on the raised pre-late weichselian beaches inside the moraine may originate from the melting of this glacier. alternatively, the moraine could correspond to the unit 5 till in the sections. this assumption would be supported by the almost total absence of glacial 46 m. hournark-nielsen & s . funder chronolinnedalen poolepynten brraggerhalveya kongsfjordhallet depositional stratigraphy (mean) (mean) (mean) (mean) environments composite log alle:lle composite log alle:ile gomposite log ai\e:ile composite log aile:lle and events local age(ky) local age (ky) amino age (ky) local age (ky) units 1 4 ~ lum units 1 4 ~ lum units 14c lorn episodes 14c lurnunh 88 9.4 11.3 d (0.020) i a s c $ a (0.018) middle -.-.a. [ 370,0,9) 55t19 weichselian f i g . 4. composite stratigraphic scheme correlating late pleistocene succesfions exposed in open sections at kongsfjordhallet, br$ggerhalv@ya, poolepynten and linncdalen. for legend see fig. 3. compiled from miller et al. (1989). mangerud et al. (1998). anderson et al. (1999) and the present study littoral emergence fiord glaciation periglacial uoob features that characterize the surface of the raised beaches (unit 6) in inland areas, and the undis turbed nature of the deposits seen in open sections. however, the freshness of the moraine and the scatter of rocks and boulders inside it suggest otherwise. we therefore favour the possibility that the kongsfjorden region experienced two fiord glaciations during the weichselian, one in the early weichselian and one during the late weichselian. in the middle weichselian the area underwent isostatic recovery, and we suggest that this may have been under periglacial conditions, despite the apparent lack of supporting evidence of sediments and other features. at isfjorden, to the south i n linncdalen (fig. 4), unit c has amino acid values similar to succession a and a corresponding or slightly younger age (lgnne 1997; mangerud et al. 1998). in linncda len, these deposits and younger middle weichse lian marine strata are overlain by till deposited during the last glacial maximum (unit d) which is covered by marine littoral deposits (unit e). correlation of sedimentary units from kongsfjor den, brfiggerhalveya, prins karls forland and linncdalen, allows us to suggest that the outer parts of the larger fiords i n spitsbergen were occupied by glaciers during the late weichselian, eemian saalian or older while other parts of the coast were left more or less ice-free. (0.030) glaciomarine shallow marine emergence glaciation discussion recent publications describing pre-holocene gla cigenic and marine sedimentary successions on svalbard have exposed differences in the inter pretation of stratigraphic data from on shore open sections (elverhgi et al. 1998). this has led to opposing models for the glacial history of the archipelago and various opinions as to the timing and extent of late weichselian glaciers. a maximum model based on the combination of core data from the shelf and deep sea drilling reveals a late weichselian barents sea ice cap reaching the shelf break, not only through the fiord mouths, but also over a wide and straight front off the coast of spitsbergen (landvik et al. 1998). contrary to this, boulton et al. (1982) and larsen et al. (1991) confine the youngest ice advance to glaciers within the fiords. evidence from land shows restricted occurrences of late weichselian till (forman 1989; miller et al. 1989; this study), a conclusion also reached by anderson et al. (1999). the latter authors advocate that the lack pleistocene stratigraphy of kongsfjordhallet, spitsbergen, svalbard 47 of glacial features and very low amino acid epimerization of early weichselian deposits signal regionally ice-free conditions during the late weichselian in the region around forlandsundet. submergence and subsequent isostatic rebound have raised the late weichselian-holocene marine deposits and terraces i n the whole region to heights between 40 and 3 0 m a d . using lehman & forman’s (1992) data, the westward decline in the height of raised late weichselian holocene shorelines along kongsfjordhallet sug gest that isostatic equilibrium along kongsfjor drenna is reached at the shelf break. this suggests the presence of a substantial late weichselian ice sheet in the region. whether the young shorelines were formed as a result of depression beneath the ice, or in the zone in front of it, or both, is not clear. the crucial point when discussing the late weichselian distribution of glaciers is the apparent lack of traces of onshore evidence such as till or glaciotectonic deformation in open sections, in comparison with offshore evidence which suggests extensive glaciation in fiord mouths and o n the shelf (mangerud et al. 1998). landvik et al. (1998) argue that glaciers may have overridden the terrain without leaving traces of erosion or deposition of till, while mangerud et al. (1998) suggest that there was ice cover over broggerhalvoya for a con siderable time ( 2 1 0 k y ) based on differences in amino acid ratios between the holocene episode a and the early weichselian episode b. svendsen et al. (1996) concluded that a late weichselian glacier reached the outer shelf through the isfjorden trough, to the south of kongsfjorden. cores from the shelf containing till overlain by shell-bearing glaciomarine diamicton indicate glacial cover and subsequent deglaciation, around 14.8 kya on the outer shelf and 12.3 kya at the fiord mouth. even though a similar glacier could have reached the shelf break through the mouth of kongsfjorden, leaving large quantities of glaci genic diamicton on the trough bottom, there is no evidence for this on either side of the fiord, at kongsfjordhallet (this study), or on kvadehuk sletta, the north-westem tip of broggerhalvbya (forman & miller 1984; lehman & forman 1992). large ice tongues flowing through the fiords are not incompatible with restricted glaciation on the adjacent land areas. although the existence of an extensive ice lobe outside kongsfjorden is un f i g . 5 . possible late weichselian ice configuration in central western spitsbergen. data compiled from fomnn (1989). milleret al. (1989). lehtnan & fomian 1992, svendsen et al. 1996. mangerud et a!. (1998). andersson et al. ( i n press) and the preaent study. k = kongsfjorden, b = br@ggerhalv@ya, p = poolepynten, l = linnivannet. 48 m . hoiminrk-nielsen & s. fiinder proven, i t is quite plausible, so we have depicted a putative glacier configuration based on data collected from open sections on spitsbergen and marine core data from the shelf (fig. 5). this minimum model allows for glaciation on the shelf break outside isfjordrenna and kongsfjordrenna. in both areas, thin or absent “onshore” tills are accompanied by large accumulations of diamicton in the fiord and troughs on the shelf. this suggests most drainage from large uplands through the major fiords. with little drainage through minor fiords between isfjorden and kongsfjorden due to restricted uplands. local glaciation on prins karls forland is proposed following the suggestion of a n d e r s o n et al. (1999). data from the western most part of spitsbergen, east of prins karls forland, indicate that glaciation was restricted to filling valleys and smaller fiord troughs (forman 1989). summing up the evidence for the extent of late weichselian glaciation in the kongsfjorden re gion, we have shown that traces of such a glaciation are sparse on the raised early weichse lian beaches and lacking in coastal sections. nevertheless. our data indicate that at least the inner part of kongsfjorden was subjected to glaciation, but are insufficient to determine whether the lateral moraine on kongsfjordhallet depicts the maximum extent of glaciation. we have combined our evidence with data from other authors into a minimum ice extent even though the previously published results have been interpreted in favour of a larger expansion of ice. the latter interpretation is supported by evidence for strong ice-rafting west of the shelf, with a debris supply from svalbard during isotope stage 2 (mangerud et al. 1998). further evidence, based on the nature of isostatic rebound, has suggested larger and more extensive glaciation along the west coast of spitsbergen (landvik et al. 1998). conclusions ( 1 ) the coastal cliffs at kongsfjordhallet show evidence for at least four phases of glaciation dating back to the early pleistocene (2 1 mya). the oldest glacial-interglacial strata have been dated by very high amino acid ratios of shells, and a characteristic fauna which includes the extinct cvrtodaria angusta. (2) the third glaciation apparently took place in the early weichselian (100-65 kya). till and glaciomarine mud, overlain by littoral sand and gravel all contain shells with amino acid aile : ile ratios of 0.026-0.036. these values are similar to other early weichselian amino acid ratios from nearby areas which experienced a late weichse lian glacier cover. (3) a comparison with other stratigraphic studies from br@ggerhalv@ya and prins karls forland suggests that a glacier tongue filled kongsfjorden during the late weichselian and deposited lateral moraines at either side of the fiord. whether this glaciation reached the shelf break via the kongs fjorden trough can only be determined by studies in the trough and on the shelf outside the fiord. ackiiom,/edge,neiirc. j. sivertsen (university of aarhus), b. sundquist (university of stockholm) and t. szinundsson (university of lund) participated i n the 1993 field work. a. lysi (university of tromso) and j . laridvik (university courses in svalbard, unis) participated in the 1996-97 field visits. j . landvik made critical comments oii the manuscript and r. dingle (university of copenhagen) kindly improved the english. references anderson. t. forman. s. ingnlfsson. 0. & manley. w. f. 1999: glacial history of central prins karls forland, western svalbard: no evidence for coverage by the barents sea ice sheet. borecrs 28(2), 292-307. boulton. g. s. 1979: glacial history of the spitsbergen archipelago and the problem of a barents shelf ice sheet. borecis 8. 3 1-57. boulton. g. s.. baldwin. c. t., peacock, j. d., mccabe, a.m.. miller. g.. jarvis, j . . horsefield, b., worsley, p.. eyles, n.. chroston, p. n., day, t. e.. gihhard, p., hare. p. e. & von bruun. v . 1982: a glacio-isostatic facies model and amino acid stratigraphy for late quaternary events in spitsbergen and the arctic. nurure 298, 437-441. elverhoi. a,. dowedeswell, j., funder. s.. mangerud, j . & stein, r. 1908: glacial and oceanic history of the polar north atlantic margins: an overview. @at. sci. rev. 17. 1-10. forman, s. l. 1989: late weichselian glaciation and deglacia tion of forlandsundet area, western spitsbergen, svalbard. boreris 18, 51-60. formaii, s. & miller, g. h . 1984: time-dependent soil morphologies and pedogenic processes on raised beaches, br(dggerhalv0ya. spitsbergen. svalhard archipelago. arctic mid alpine reseorch 16. 381-394. funder, s. 1993: pie-holocene marine faunas from spitsbergen -field observations. i n landvik. j . (ed.): pona:,field uurk in s i d b a r d 1993. pp. 3 1-39. longyearbyen, svalbard: unis. hjelle, a. & lauritzen, 0. 1982: gro/ogicrd iniip of’svcilbard. i : soo,ooo, sheet 3g. spiisbergeii, norrhern port. oslo: norwegian polar institute. houmark-nielsen, m., sivertsen. j., sundqvist. 8. & szmunds son. t. 1993: quaternary stratigraphy of kongsfjordhallet. west spitsbergen. in landvik, j . (ed.): ponam:,fieldworx in svalbnrd 1993. pp. 22-30, longyearbyen, svalbxd: unis. pleistocene stratigruphy of kongsfjordhallet, spitsbergen, svalbard 49 landvik, j., bondevik, s.. elverhfli. a,, fjeldskaar, w . . mangerud, j., siegert, m . j., salvigsen. o., svendsen, j . i. & vorren. t. 1998: the last glacial maximum ofsvalbard and the barents sea area: ice sheet extent and configuration. qruri. sci. rec. 17, 13-75. larsen, e.. sejrup, h. p., olsen, l. & miller, g. 1991: l:ik quaternary land-sea interactions: fennoscandia and svalhard the nordic seas. qital. b i l . 10-12, 151-159. lehman. s . j . & forman, s. l. 1992: late weichnelian glacier retreat i n kongsfiorden. west spitqhergen, svalbard. ointr. r e s . 37, 139-154. lflnne, 1. 1997: facies characteristics of a proglacial turbiditic sand-lobe at svalbard. sediment. geul. 109, 13-35. mangerud. j., dokken, t.. hebheln. d.. heggen, b.. l n g d l f ~ v i n , 0.. landvik, j.. mejdahl. v. svendsen, j. i . & vorren, t. 1998: fluctuations of the svalbard-barents sea ice sheet during the last 150,000 years. qucrr. sci. rev. 17. 1 1 4 2 . miller, g. h. 1982: quaternary depositional episodes. webtern spitsbergen. norway: minostratigraphy and glacial history. a r c t i c ond alpine reseurcli 21. 32 1-340. miller, g. h.. sejrup, h. p., lehman, s. j. & forman, s. l. 1989: glacial history and marine environmental change during the last interglacial-glacial cycle, western spitsbergen. svalbard. boreris 18, 273-296. murray. a. s. & mejddhl, v. 1999: comparison ofregenerative dose single-aliquot and multiple-aliquot (sara) protocols using heated quartz from archaeological sites. qircit. sci. r e v . 18, 223-229. murray, a. s. & roberts, r. g. 1998: measurement of equivalent dose in the quartz using a regenerative-dose single-aliquot protocol. rodinrim meas. 29, 503-5 is. sejrup, h . p. 1990: amino acid geochronology. late quaternary stratigraphy and glaciology in the thule area. northwest greenland (s. funder ed.). medd. grqirilurrd geoscierice 22. 36-39. svendsen, j . i . , elverhuri, a. & mangerud, j. 1996: the retreat of the barents sea ice sheet on the western svalbard margin. boreur 2.5, 244-256. doi:10.3402/polar.v32i0.11133 r e s e a r c h / r e v i e w a r t i c l e abundance and breeding distribution of seabirds in the northern part of the danco coast, antarctic peninsula diego gonzález-zevallos,1 m. mercedes santos,2 emilce f. rombolá,2 mariana a. juáres2,3 & néstor r. coria 2 1 centro nacional patagónico (consejo nacional de investigaciones cientı́ficas y técnicas), blvd. brown 2915 (9120), puerto madryn, chubut, argentina 2 instituto antártico argentino � división biologı́a, cerrito 1248 (1010), buenos aires, argentina 3 consejo nacional de investigaciones cientı́ficas y técnicas, rivadavia 1917 (1033), buenos aires, argentina keywords seabird abundances; breeding distribution; danco coast; antarctic peninsula. correspondence diego gonzález-zevallos, centro nacional patagónico, blvd. brown 2915 (9120), puerto madryn, chubut, argentina. e-mail: diegue@cenpat.edu.ar abstract seabird abundances and breeding distribution have the potential to serve as ecological indicators. the western antarctic peninsula is one of the three sites in the world with the greatest increases in local temperature during the last 50 years. the aim of this study was to monitor the distribution and abundance of breeding populations of seabirds in the northern sector of the danco coast, north-west of the antarctic peninsula, during the breeding season 2010/11. the birds were the wilson?s storm petrel (oceanites oceanicus), south polar skua (stercorarius maccormicki), kelp gull (larus dominicanus), antarctic tern (sterna vittata), snowy sheathbill (chionis alba), chinstrap penguin (pygoscelis antarctica), southern giant petrel (macronectes giganteus), gentoo penguin (pygoscelis papua), cape petrel (daption capense) and antarctic shag (phalacrocorax bransfieldensis). annual breeding population growth increased in pygoscelids, southern giant petrel and sheathbill, and for the remaining species, breeding population trends were stable. given that seabird populations can provide valuable information on the conditions of their feeding and nesting environments, this study highlights the need to maintain basics monitoring studies. studies of seabird populations can provide valuable indicators on the conditions of their feeding and nesting environments in relation to global-scale processes (croxall et al. 1988). climatic and oceanographic variability and change have been shown to affect seabirds, often with profound consequences, like reduced breeding success and altered breeding cycles for some species (chambers et al. 2011). three regions in the world are recognized as having warmed more rapidly during the last 50 years (vaughan et al. 2003). located in the southern hemisphere, one of these three regions includes the region west of the antarctic peninsula (smith et al. 1999; vaughan et al. 2001; gille 2002; cook et al. 2005). the populations of various species of penguins in this region have shown responses to increases in air temperature, retreat of the glaciers and decreases in the frequency of cold years in association with a decrease of sea ice in winter and its negative effects on the abundance of krill (siegel & loeb 1995; loeb et al. 1997; fraser & hofmann 2003). in this context, long-term surveys are essentials to document population trends. the present study evaluated the breeding population size and distribution of marine birds in the northern sector of the danco coast, antarctic peninsula, including the antarctic specially protected area (aspa) no. 134. study area and methods the study was conducted in the northern sector of the danco coast during the 2010/11 breeding season, which lasts from 24 december 2010 until 20 february 2011. several sites were surveyed between cape herschell and (page number not for citation purpose) polar research 2013. # 2013 d. gonzález-zevallos et al. this is an open-access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2013, 32, 11133, http://dx.doi.org/10.3402/polar.v32i0.11133 http://www.polarresearch.net/index.php/polar/article/view/11133 http://dx.doi.org/10.3402/polar.v32i0.11133 spring point (fig. 1). the sampling area covered the mar rock, cierva point, moss island, midas island and sterneck islands, all lying within aspa no. 134. counts of apparently occupied nests of penguins were made by eye from the single highest point of each selected area (exposed rocky patches), with contiguous areas covering each colony in its entirety. counts of apparently occupied nest of flying birds were made by eye and by using 40 �binoculars. we obtained the number of apparently occupied nests in each area based on the mean of the three counts (table 1). counts of wilson?s storm petrels (oceanites oceanicus) were also made but were not considered due to their high inaccuracy. the presence of two possible nests of brown skua (stercorarius lonnbergi) was noted in cierva point, but for this study we considered all these birds as south polar skuas (stercorarius maccormicki). changes in breeding population sizes were compared with those obtained in 1997/98 (favero et al. 2000) for the same sampling localities. the annual breeding population growth rate was calculated as l�(ns2/ns1)^(1/t), where n represents the breeding population size and s the season (s1: 1997/98 and s2: 2010/11) and t is the number of seasons between the two surveys (t �13). lambda (l) indicates if the population increases (l�1), decreases (lb1) or remains stable (l�1) through time (caswell 1989). results the survey registered the presence of a total of 11 species of seabirds, 10 of them breeding in the study area. we recorded the presence of snow petrel (pagodroma nivea) on two visits to moss island. although no nests were found, we suspect that this highly cryptic species breeds on the island. the species seen to be breeding were, from most common to least common: wilson?s storm petrel, south polar skua, kelp gull (larus dominicanus), antarctic tern (sterna vittata), snowy sheathbill (chionis alba), chinstrap penguin (pygoscelis antarctica), southern giant petrel (macronectes giganteus), gentoo penguin (pygoscelis papua), cape petrel (daption capense) and antarctic shag (phalacrocorax bransfieldensis). sterneck island was the site with the highest number of breeding species (nine species), followed by py and alcock and midas islands (eight species) and then by moss islands and cierva point (seven species). no other site exceeded six species of seabirds present. in pygoscelids, gentoo penguin breeding colonies showed increases in all localities analysed (table 2). the breeding colonies of chinstrap penguin showed increases and decreases, but the overall trend for the study area was an increase (table 3). in flying birds the annual population growth rates showed increases in southern giant petrel and sheathbill and decreases in cape petrel and kelp gull. for the remaining flying birds, breeding population trends were stable (table 4). fig. 1 map of the study area showing the different localities sampled and the primavera base (marked with an open circle) and the antarctic specially protected area (aspa) no. 134 (light grey), including the marine areas between the islands and the mainland. table 1 positions and dates of population surveys conducted at each site from december 2010 to february 2011. locality latitude longitude date cierva point 64809?28.0??s 60857?14.5??w 30 dec. moss islands 64809?56.3??s 61802?05.7??w 8 jan. sucia point 64810?50.3??s 60857?13.0??w 10 jan. py point 64813?25.4??s 61800?13.0??w 11 jan. sterneck island 64812?03.7??s 60859?12.7??w 12 jan. mar rock 64808?35.3??s 60859?06.6??w 15 jan. kay rock 64807?33.8??s 60855?51.6??w 17 jan. charles point 64814?04.3??s 60859?40.1??w 20 jan. midas island 64810?18.3??s 61805?05.9??w 6 feb. alcock island 64814?13.9??s 61807?21.3??w 9 feb. sprightly island 64816?58.5??s 61804?34.3??w 9 feb. spring point 64817?38.5??s 61803?00.5??w 9 feb. cape herschel 64804?40.7??s 61801?53.9??w 12 feb. breeding population sizes of danco coast birds d. gonzález-zevallos et al. 2 (page number not for citation purpose) citation: polar research 2013, 32, 11133, http://dx.doi.org/10.3402/polar.v32i0.11133 http://www.polarresearch.net/index.php/polar/article/view/11133 http://dx.doi.org/10.3402/polar.v32i0.11133 discussion spots censuses can give misleading impressions of the actual status of populations (croxall et al. 1988). however, in order to understand ecological drivers for the population trends observed in seabirds, it is still necessary to have a regional vision of the status of the populations, and for that purpose, even opportunistic visits to colonies provide valuable information (lynch et al. 2008). species richness among the sites studied ranged between two and nine, with the wilson?s storm petrel present in all localities. in general, the breeding populations of pygoscelids, southern giant petrels and snowy sheathbills increased, whereas those of cape petrels and kelp gulls decreased. these increases and decreases could be attributed to the variability of the environment and/or different counting techniques used in other decades in association with different meteorological conditions. for this reason, arbitrarily and applying a more conservative approach, we only discuss here those species for which annual population growth rate (l) was below 0.97 or above 1.03. population trends of pygoscelids penguins in the antarctic peninsula and associated islands have been studied by numerous authors (woehler & croxall 1997; hinke et al. 2007; sander, balbao, costa et al. 2007; sander, balbao, polito et al. 2007; carlini et al. 2009; trivelpiece et al. 2011; lynch, ron et al. 2012; lynch, william et al. 2012; among many others). the contrasting trends between species are of particular interest because as top predators, they integrate and/or magnify changes in the lower levels of the food chain. thus, penguins, who have different affinities to sea ice, provided some of the first evidence linking changes in the physical environment to their biological responses (fraser et al. 1992; rombolá et al. 2003; forcada et al. 2006; trathan et al. 2007; nicol et al. 2008; forcada & trathan 2009). ice reduction will adversely impact the winter over survival of krill larvae and the reproductive output of female krill and as consequence diminish krill recruitment (flores et al. 2012), which in turn impacts krill availability to top predators. furthermore, sea-ice loss impacts directly on the wintering habitats of seaice dependent species like adélie penguins (pygoscelis adeliae), and favours an increase in ice-intolerant gentoo and chinstrap penguins (mc clintock et al. 2008). climate warming also brings more years with more table 2 number of breeding pairs per location for gentoo penguin in the northern sector of danco coast. parentheses indicate the year the count was conducted. lambda (l) represents the annual breeding population growth rate, n represent the breeding population size and s the season (s1: 1997/98 and s2: 2010/11). locality novatti (1978) poncet & poncet (1987) quintana et al. (1998) favero et al. (2000) (ns1) this study (ns2) l cierva point 559�614 (1954�58) 600 (1984) 800�1041 (1991�96) 593 (1998) 2680 1.12 sterneck island 450 (1987) 905 (1998) 2795 1.09 py point 130 (1987) a 390 (1998) a 655 1.06 charles point 140 total � 1180 � 1888 6270 1.10 a localities grouped. table 3 number of breeding pairs by location for chinstrap penguin in the northern sector of danco coast. parentheses indicate the year the count was conducted. lambda (l) represents the annual breeding population growth rate, n represent the breeding population size and s the season (s1: 1997/98 and s2: 2010/11). locality muller-schwarze (1975) poncet & poncet (1987) woehler (1993) favero et al. (2000) (ns1) this study (ns2) l cape herschel 316 (1998) 650 1.06 kay rock 21 (1998) 0 0.00 mar rock 500 (1984) 1553 (1998) 2763 1.05 midas island 2060 (1971) 200 (1987) 546 (1998) 180 b 0.92 sterneck island 1100 (1987) 152b (1998) 33 0.89 py point 10 (1987) a 13 (1998) a 10 0.98 charles point 0 alcock island 7710 (1971) 10000 (1971) 3000 (1990) 605 (1998) 1100 1.05 spring point 85 (1984) 60 (1990) 180 (1998) a 0 0.96 sprightly island 110 total 9770 11895 3060 3386 4846 1.03 a localities grouped. b possible underestimation. d. gonzález-zevallos et al. breeding population sizes of danco coast birds citation: polar research 2013, 32, 11133, http://dx.doi.org/10.3402/polar.v32i0.11133 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/11133 http://dx.doi.org/10.3402/polar.v32i0.11133 snow (turner et al. 2005; thomas et al. 2008). snow accumulation, snow melting and solar radiation impact the microclimate of breeding colonies and influence the selection of nesting sites among pygoscelis species (trivelpiece & fraser 1996; boersma 2008; lynch et al. 2009; ainley 2010), so differences in the breeding chronology will determine which one is mainly affected. despite all evidences described in the literature about how climate change is operating on antarctic peninsula and its consequences for penguin populations, our results on pygoscelis penguins showed an increase. though the danco coast area is not under pressure from krill fisheries (ccamlr 2011), krill availability to top predators may vary by natural causes and/or may be influenced by sea-ice reduction and availability of winter habitats. the biological responses to sea-ice and climatic variability are often extremely complex and may differ regionally and locally (stenseth et al. 2002; forcada et al. 2006). winter sea-ice extent in the western antarctic peninsula exhibits high interanual variability, but ice maxima are episodic and high-ice years are invariably followed by several low-ice years that together form a distinct series or cycle (fraser & hoffmann 2003). future results including diet information and breeding phenology will be necessary to identify how climate change is operating at danco coast on penguin populations. overall, population trends of southern giant petrels varied between different localities on the antarctic peninsula and sub-antarctic islands and in patagonia, argentina, linked to human activity (chupin 1997; nel et al. 2002; pfeiffer & peter 2004; patterson et al. 2008), habitat loss or degradation (parks and wildlife service and biodiversity conservation branch 2007) or food availability (patterson et al. 2008). in general, those populations located in areas with human disturbance (accumulation of garbage, pollution, tourism, fisheries, predation by introduced animals) are suffering a decline (woehler et al. 2001; patterson et al. 2008), while in areas with less disturbance their populations are increasing (woehler et al. 2001; lynch et al. 2008). our study area is within or near aspa no. 134, where visits (by scientists and tourists) are not frequent. the number of tourists who visited cierva cove during the study year was 1272 (iaato 2011), constituting only 0.4% of total tourists visiting the antarctic region. increases in the southern giant petrel population size at danco coast could be related to the relatively undisturbed area. pairs of breeding sheathbills maintain foraging and breeding territories centred on colonies of breeding seabirds, usually penguins (burger 1981). in these habitats, they feed on eggs, carrion, faeces and perform kleptoparisitism (downes et al. 1959; burger 1981; weimerskircht a b le 4 n u m b e r o f b re e d in g p a ir s p e r lo c a ti o n fo r th e sp e c ie s a n ta rc ti c sh a g (a s ; p h a la c ro c o ra x b ra n sfi e ld e n si s) , so u th e rn g ia n t p e tr e l (s g p ; m a c ro n e c te s g ig a n te u s) , c a p e p e tr e l (c p ; d a p ti o n c a p e n se ), sn o w y sh e a th b ill (s s ; c h io n is a lb a ), s o u th p o la r sk u a (s p s ; s te rc o ra ri u s m a c c o rm ic k i) , k e lp g u ll (k g ; l a ru s d o m in ic a n u s) a n d a n ta rc ti c te rn (a t ; s te rn a v it ta ta ), in th e n o rt h e rn se c to r o f th e d a n c o c o a st . l a m b d a (l ) re p re se n ts th e a n n u a l b re e d in g p o p u la ti o n g ro w th ra te , n re p re se n t th e b re e d in g p o p u la ti o n si ze a n d s th e se a so n (s 1 : 1 9 9 7 /9 8 a n d s2 : 2 0 1 0 /1 1 ). a s s g p c p s s s p s k g a t l o c a lit y n s1 n s2 l n s1 n s2 l n s1 n s2 l n s1 n s2 l n s1 n s2 l n s1 n s2 l n s1 n s2 l c a p e h e rs c h e l 2 8 2 4 0 .9 9 0 0 � 2 0 0 1 1 1 2 0 0 2 4 1 .0 5 0 1 0 � c ie rv a p o in t 0 0 � 0 0 � 7 3 0 .9 4 2 1 0 .9 5 1 4 5 1 6 6 1 .0 1 1 5 8 7 3 0 .9 4 4 5 5 7 1 .0 2 k a y r o c k 0 0 � 0 0 � 0 0 � 0 0 � 1 4 1 .1 1 0 0 � 0 0 � m a r r o c k 9 0 0 0 0 � 1 0 0 3 1 0 .9 2 3 3 1 8 1 0 1 .0 2 0 3 � m o ss is la n d s 0 0 � 3 5 4 2 1 .0 1 2 8 1 7 0 .9 6 3 4 1 .0 2 1 0 2 6 1 .0 8 1 2 0 7 0 0 .9 6 1 5 1 9 1 .0 2 m id a s is la n d 2 1 2 1 1 0 7 b � 0 0 � 1 1 1 3 1 7 1 .1 4 1 5 9 0 .9 6 3 5 1 1 b 0 .9 1 s u c ia p o in t 0 0 � 4 7 6 8 1 .0 3 0 0 � 0 0 � 2 5 b 3 2 1 .0 2 3 5 3 1 0 .9 9 1 5 2 2 1 .0 3 s te rn e c k is la n d 0 0 � 5 b 4 1 1 .1 7 2 3 1 1 0 .9 4 1 b 2 1 .0 5 2 b 1 2 1 .1 5 6 8 1 2 0 .8 7 1 5 1 2 0 .9 8 p y p o in t 2 2 3 4 1 .0 3 0 0 � 0 0 � 1 4 1 .1 1 0 5 � 3 5 7 0 .8 8 2 0 1 1 0 .9 5 c h a rl e s p o in t 0 0 � 0 0 � 0 0 � 0 1 � 4 0 b 3 1 0 .9 8 1 0 5 9 8 0 .9 9 1 5 b 3 2 1 .0 6 a lc o c k is la n d 2 0 0 5 b 3 b 0 .9 6 7 b 1 1 1 .0 3 4 1 2 1 .0 9 7 b 1 9 1 .0 8 3 7 7 0 1 .0 5 2 0 b 6 5 1 .0 9 s p ri n g p o in t 1 0 a 0 0 0 a 0 � 0 a 0 � 0 a 0 � 4 a 1 2 1 .1 3 2 5 a ,b 3 5 1 .0 6 1 5 a 0 0 .9 3 s p ri g h tl y is la n d 0 0 0 0 8 1 8 6 t o ta l 9 2 7 9 0 .9 9 9 2 1 6 1 1 .0 4 6 8 4 2 0 .9 6 1 6 2 7 1 .0 4 2 4 2 3 3 5 1 .0 2 6 0 8 4 3 7 0 .9 7 1 9 5 2 4 8 1 .0 2 a s p ri n g p o in t a n d s p ri g h tl y is la n d w e re g ro u p e d in n s1 . b p o ss ib le u n d e re st im a ti o n . breeding population sizes of danco coast birds d. gonzález-zevallos et al. 4 (page number not for citation purpose) citation: polar research 2013, 32, 11133, http://dx.doi.org/10.3402/polar.v32i0.11133 http://www.polarresearch.net/index.php/polar/article/view/11133 http://dx.doi.org/10.3402/polar.v32i0.11133 1989; verheyden & jouventin 1991). therefore, it is highly probable that the increases in abundance of snowy sheathbills recorded in the present study are related to breeding population growth observed in pygoscelids. in contrast, the possible causes that could explain the decrease in the breeding populations of cape petrels and kelp gulls remain unknown. the study area has a high species richness, both animal and vegetable (dirección nacional del antártico 2002). in turn, the highest abundance of birds, primarily pygoscelids, was within aspa no. 134. the singular topography, along with the abundance and diversity of species, provides favourable conditions for the formation of numerous microhabitats, providing an exceptional scientific value to the area (dirección nacional del antártico 2002). the present study highlights the need to maintain basics monitoring studies. acknowledgements the study was supported by the dirección nacional del antártico, instituto antártico argentino and the dirección antártica. we are grateful for the cooperation agreement between the marine mammal laboratory of the instituto antártico argentino and the university of new south wales and taronga conservation society australia. we thank anonymous reviewers and dr c. patrick doncaster for their constructive comments. special thanks to j. mennucci, h. merlo álvarez, f. isla, v. llampa, j. gómez, f. villalba, r.c. larrea, m. tucker, w.e. varela, e.h. toso, m.a. schell, c. asti and d. slip. references ainley d., russell j., jenouvrier s., woehler e., lyver p.o.b., fraser w.r. & kooyman g.l. 2010. antarctic penguin response to habitat change as earth’s troposphere reaches 28c above pre-industrial levels. ecological monographs 80, 49�66. boersma p.d. 2008. penguins as marine sentinels. bioscience 58, 597�607. burger a.e. 1981. time budget, energy needs and kleptoparasitism in breeding lesser sheathbills (chionis minor). the condor 83, 106�112. carlini a.r., coria n.r., santos m.m., negrete j., juares m.a. & daneri g.a. 2009. responses of pygoscelis adeliae and p. papua populations to environmental changes at isla 25 de mayo (king george island). polar biology 32, 1427�1433. caswell h. 1989. matrix population models. construction, analysis, and interpretation. sunderland, ma: sinauer associates. ccamlr 2011. krill fishery report: 2011 update. wg-emm-11/5. hobart: commission for the conservation of antarctic marine living resources secretariat. chambers l.e., devney c.a., congdon b.c., dunlop n., woehler e.j. & dann p. 2011. observed and predicted effects of climate on australian seabirds. emu 111, 235�251. chupin i. 1997. human impact and breeding success in southern giant petrel (macronectes giganteus) on king george island (south shetland islands). korean journal of polar research 8, 113�116. cook a.j., fox a.j., vaughan d.g. & ferrigno j.g. 2005. retreating glacier-fronts on the antarctic peninsula over the last 50 years. science 22, 541�544. croxall j.p., mccann t.s., prince p.a. & rothery p. 1988. reproductive performance of seabirds and seals at south georgia and signy island, south orkney islands, 1976�1987: implications for southern ocean monitoring studies. in d. sahrhage (ed.): antarctic ocean and resource variability. pp. 261�285. new york: springer. dirección nacional del antártico 2002. plan de gestión de la zona antártica especialmente protegida no 134 punta cierva e islas offshore, costa danco, penı́nsula antártica. (management plan for antarctic specially protected area no. 134 cierva point and offshore islands, danco coast, antarctic peninsula.) buenos aires: áreas protegidas, dirección nacional del antártico. downes m.c., ealey e.h.m., gwynn a.m. & young p.s. 1959. the birds of heard island. anare reports 51. melbourne: antarctic division, department of external affairs. favero m., coria n.r. & beron m.p. 2000. the status of breeding birds at cierva point and surroundings, danco coast, antarctic peninsula. polish polar research 21, 181�187. flores h., van franeker j.a., siegel v., haraldsson m., strass v., hubert meesters e., bathmann u. & jan wolff w. 2012. the association of antarctic krill euphausia superba with the under-ice habitat. plos one 7(2), e31775, doi: 10.1371/journal.pone.0031775. forcada j. & trathan p.n. 2009. penguins responses to climate change in the southern ocean. global change biology 7, 1618�1630. forcada j., trathan p.n., reid k., murphy e.j. & croxall j.p. 2006. contrasting population changes in sympatric penguin species in association with climate warming. global change biology 12, 411�423. fraser w.r. & hofmann e. 2003. a predator’s perspective on causal links between climate change, physical forcing and ecosystem response. marine ecology progress series 265, 1�15. fraser w.r., trivelpiece w.z., ainley d.g. & trivelpiece s.g. 1992. increases in antarctic penguin populations: reduced competition with whales or a loss of sea ice due to environmental warming? polar biology 11, 525�531. gille s.t. 2002. warming of the southern ocean since the 1950s. science 295, 1275�1277. hinke j.t., salwicka k., trivelpiece s.g., watters g.m. & trivelpiece w.z. 2007. divergent responses of pygoscelis penguins reveal common environmental driver. oecologia 153, 845�855. iaato (international association of antarctica tour operators) 2011. tourism statistics. accessed on the internet at http://iaato.org/es/tourism-statistics on 22 january 2013. d. gonzález-zevallos et al. breeding population sizes of danco coast birds citation: polar research 2013, 32, 11133, http://dx.doi.org/10.3402/polar.v32i0.11133 5 (page number not for citation purpose) http://iaato.org/es/tourism-statistics http://www.polarresearch.net/index.php/polar/article/view/11133 http://dx.doi.org/10.3402/polar.v32i0.11133 loeb v., siegel v., holm-hansen o., hewitt r., fraser w., trivelpiece w. & trivelpiece s. 1997. effects of sea-ice extent and krill or salp dominance on the antarctic food web. nature 387, 897�900. lynch h.j., fagan w.f., naveen r., trivelpiece s.g. & tricelpiece w.z. 2009. timing of clutch initiation in pygoscelis penguins on the antarctic peninsula: towards an improved understanding of off-peak census correction factors. ccamlr science 16, 149�165. lynch h.j., naveen r. & fagan w.f. 2008. censuses of penguin, blue-eyed shag phalacrocorax atriceps and southern giant petrel macronectes giganteus populations on the antarctic peninsula, 2001�2007. marine ornithology 36, 83�97. lynch h.j., ron n., philip n.t. & william f.f. 2012. spatially integrated assessment reveals widespread changes in penguin populations on the antarctic peninsula. ecology 93, 1367�1377. lynch h.j., william f.f., ron n., trivelpiece s.g. & trivelpiece w.z. 2012. differential advancement of breeding phenology in response to climate may alter staggered breeding among sympatric pygoscelid penguins. marine ecology progress series 454, 135�145. mc clintock j., ducklow h. & fraser w. 2008. ecological responses to climate change on the antarctic peninsula. the scientific research society 96, 302�310. muller-schwarze c. & muller-schwarze d. 1975. a survey of twenty-four rookeries of pygoscelid penguins in the antarctic peninsula region. in b. stonehouse (ed.): the biology of penguins. pp. 309�320. london: macmillan. nel d.c., ryan p.g., crawford r.j.m., cooper j. & huyser o.a.w. 2002. population trends of albatrosses and petrels at sub-antarctic marion island. polar biology 25, 81�89. nicol s., clarke j., romaine s.j., kawaguchi s., williams g. & hosie g.w. 2008. krill (euphausia superba) abundance and adélie penguin (pygoscelis adeliae) breeding performance in the waters off the béchervaise island colony, east antarctica in 2 years with contrasting ecological conditions. deep-sea research part ii 55, 540�557. novatti r. 1978. notas ecológicas y etológicas sobre las aves de cabo primavera, costa de danco, penı́nsula antártica. (ecological and ethological notes on birds in spring point, danco coast, antarctic peninsula.) contribución instituto antártico argentino 237. buenos aires: argentine antarctic institute. parks and wildlife service and biodiversity conservation branch 2007. plan for the eradication of rabbits and rodents on subantarctic macquarie island. hobart: parks and wildlife service, dept. of tourism, arts and the environment, and biodiversity conservation branch, dept. of primary industries and water. patterson d.l., woehler e.j., croxall j.p., cooper j., poncet s., peter h.-u., hunter s. & fraser w.r. 2008. breeding distribution and population status of the northern giant petrel macronectes halli and the southern giant petrel m. giganteus. marine ornithology 36, 115�124. pfeiffer s. & peter h.u. 2004. ecological studies toward the management of an antarctic tourist landing site (penguin island, south shetland islands). polar record 40, 345�353. poncet s. & poncet j. 1987. censuses of penguin populations of the antarctic peninsula, 1983�87. british antarctic survey bulletin 77, 109�129. quintana r.d., cirelli v. & orgeira j.l. 1998. abundance and spatial distribution of bird populations at cierva point, antarctic peninsula. marine ornithology 28, 21�27. rombolá e., marschoff e. & coria n. 2003. comparative study of the effects of the late pack-ice break-off on chinstrap and adélie penguins’ diet and reproductive success at laurie island, south orkney islands, antarctica. polar biology 26, 41�48. sander m., balbao t.c., costa e.s., dos santos c.r. & petra m.v. 2007. decline of the breeding population of pygoscelis antarctica and pygoscelis adeliae on penguin island, south shetlands, antarctica. polar biology 30, 651�664. sander m., balbao t.c., polito m.j., costa e.s. & carneiro a.p.b. 2007. recent decrease in chinstrap penguin (pygoscelis antarctica) populations at two of admiralty bay’s islets on king george island, south shetland islands, antarctica. polar biology 30, 659�661. siegel v. & loeb v. 1995. recruitment of antarctic krill euphausia superba and possible causes for its variability. marine ecology progress series 123, 45�56. smith r.c., ainley d., baker k., domack e., emslie s., fraser s., kennet a., mosley-thomson e., stammerjohn s. & vernet m. 1999. marine ecosystem sensitivity to climate change. bioscience 49, 393�404. stenseth n.c., mysterud a., ottersen g., hurrell j.w., chan k-s. & lima m. 2002. ecological effects of climate fluctuations. science 297, 1292�1296. thomas e.r., marshall g.j. & mcconnell j.r. 2008. a doubling in snow accumulation in the western antarctic peninsula since 1850. geophysical research letters 35, l01706, doi: 10.1029/2007gl032529. trathan p.n., forcada j. & murphy e.j. 2007. environmental forcing and southern ocean marine predator populations: effects of climate change and variability. philosophical transactions of the royal society b 362, 2351�2365. trivelpiece w.z. & fraser w.r. 1996. the breeding biology and distribution of adelie penguins: adaptations to environmental variability. in r. ross (ed.): foundations for ecological research west of the antarctic peninsula. pp. 273�285. washington, dc: american geophysical union. trivelpiece w.z., hinke j.t., miller a.k., reiss c.s., trivelpiece s.g. & watters g.m. 2011. variability in krill biomass links harvesting and climate warming to penguin population changes in antarctica. proceedings of the national academy of sciences of the united states of america 108, 7625�7628. turner j., lachlan-cope t., colwell s. & marshall g. 2005. a positive trend in western antarctic peninsula precipitation over the last 50 years reflecting regional and antarcticwide atmospheric circulation changes. annals of glaciology 41, 85�91. breeding population sizes of danco coast birds d. gonzález-zevallos et al. 6 (page number not for citation purpose) citation: polar research 2013, 32, 11133, http://dx.doi.org/10.3402/polar.v32i0.11133 http://www.polarresearch.net/index.php/polar/article/view/11133 http://dx.doi.org/10.3402/polar.v32i0.11133 vaughan d.g., marshall g.j., connolley w.m., king j.c. & mulvaney r. 2001. climate change: devil in the detail. science 293, 1777�1779. vaughan d.g., marshall g.j., connolley w.m., parkinson c., mulvaney r., hodgson d.a., king j.c., pudsey c.j. & turner j. 2003. recent rapid regional climate warming on the antarctic peninsula. climate change 60, 243�274. verheyden c. & jouventin p. 1991. over-wintering strategies of the lesser sheathbill chionis minor in an impoverished and insular environment. oecologı́a 86, 132�139. weimerskirch 1989. the avifauna of the kerguelen islands. emu 89, 15�29. woehler e.j. 1993. the distribution and abundance of antarctic and subantarctic penguins. cambridge: scientific committee on antarctic research. woehler e.j., cooper j., croxall j.p., fraser w.r., kooyman g.l., millar g.d., nel d.c., patterson d.l., peter h.-u., ribic c.a., salwicka k., trivelpiece w.z. & weimerskirch h. 2001. a statistical assessment of the status and trends of antarctic and subantarctic seabirds. cambridge: scientific committee on antarctic research. woehler e.j. & croxall j.p. 1997. the status and trends of antarctic and sub-antarctic seabirds. marine ornithology 25, 43�66. d. gonzález-zevallos et al. breeding population sizes of danco coast birds citation: polar research 2013, 32, 11133, http://dx.doi.org/10.3402/polar.v32i0.11133 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/11133 http://dx.doi.org/10.3402/polar.v32i0.11133 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <feff004f007000740069006f006e00730020007000650072006d0065007400740061006e007400200064002700e900760061006c0075006500720020006c006100200063006f006e0066006f0072006d0069007400e9002000e00020006c00610020006e006f0072006d00650020005000440046002f0058002d003300200065007400200064006500200063006f006e0064006900740069006f006e006e006500720020006c0061002000700072006f00640075006300740069006f006e00200064006500200064006f00630075006d0065006e007400730020005000440046002000e000200063006500740074006500200063006f006e0066006f0072006d0069007400e9002e0020005000440046002f0058002000650073007400200075006e00650020006e006f0072006d0065002000490053004f00200064002700e9006300680061006e0067006500200064006500200063006f006e00740065006e00750020006700720061007000680069007100750065002e00200050006f0075007200200065006e0020007300610076006f0069007200200070006c0075007300200073007500720020006c006100200063007200e9006100740069006f006e00200064006500200064006f00630075006d0065006e00740073002000500044004600200063006f006e0066006f0072006d00650073002000e00020005000440046002f0058002d0033002c00200063006f006e00730075006c00740065007a0020006c00650020004700750069006400650020006400650020006c0027007500740069006c0069007300610074006500750072002000640027004100630072006f006200610074002e00200049006c002000650073007400200070006f0073007300690062006c0065002000640027006f00750076007200690072002000630065007300200064006f00630075006d0065006e007400730020005000440046002000640061006e00730020004100630072006f0062006100740020006500740020005200650061006400650072002c002000760065007200730069006f006e00200034002e00300020006f007500200075006c007400e9007200690065007500720065002e> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu (settings for the rampage workflow.) >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice divine.indd 27divine et al. 2003: polar research 22(1), 27–34 the winter ice regime of the kara sea is characterized by the formation of large zones of stationary ice. fast ice usually starts to form near the shoreline at the end of october to the beginning of november and expands seaward during december–february. it tends to reach its stable maximum in april–may. by this time the fast ice edge typically attains 10 m depth in the western part of the kara sea. in the eastern kara sea it can reach depths of about 20–30 m and even 100 m near the severnaya zemlya archipelago. the most extensive stretch of fast ice is observed in the north-eastern kara sea, where numerous islands and shallow banks prevent the ice from moving; fast ice extent in this area can attain hundreds of kilometres (zubov 1945; timokhov 1994; borodachev 1998). in years when the extent of fast ice has been especially large, the boundary of fast ice in the north-eastern kara sea extends from the tip of the yamal peninsula to the northern end of severna zemlya. in years when the observed fast ice extent has been particularly small, its border hugs the mainland (fig. 1). the investigation of shore-fast ice is important from several points of view. the presence of fast ice restricts offshore exploration and affects navigation. variation of the extent of fast ice may indicate climate change both locally and on a global scale. the recurrent polynya bordering fast ice is the area where intensive heat exchange between the relatively warm water exposed to cold air occurs, resulting in the intensive formation of new ice and dense water (dethleff et al. 1998). it is also believed that regions of fast ice and quasi-stationary polynyas are signifi cant for variability and climate sensitivity of fast ice extent in the north-eastern kara sea dmitry divine, reinert korsnes & alexander makshtas this work investigates the temporal and spatial variation of shore-fast ice extent in the north-eastern part of the kara sea during 1953–1990 and its sensitivity to interannual variability of the regional climate. the area of fast ice in spring months shows a bimodal distribution. this indicates the existence of two different regimes of fast ice formation driven by the system of prevailing winds. the westward wind transport during the cold season gives larger fast ice extent while the eastward wind transport suppresses the expansion of fast ice. there is a signifi cant correlation (ca. –0.55) between the average winter temperature and the area of fast ice. linear trends for time records of shore-fast ice area in spring show a decrease during 1953–1990. this decrease is most pronounced in april: the mean fast ice area in april is 12 % lower in 1988–1990 compared to 1953–55. a comparison of fast ice regimes for two particular years— 1979 and 1985—revealed a signifi cant infl uence of cyclone activity on fast ice development over the course of the cold season. it is shown that partial break-ups of fast ice in spring 1985 are associated with the passage of cyclones across the area of fast ice. d. v. divine, norwegian polar institute, polar environmental centre, n-9296 tromso, norway, divine@ npolar.no; r. korsnes, norwegian defense research establishment, box 25, n-2007 kjeller, norway; a. p. makshtas, international arctic research center, 930 koyukuk drive, box 757340, fairbanks, ak 99775, usa. 28 variability and climate sensitivity of fast ice extent uptake of particulate materials and contaminants into sea ice from seawater (reimnitz et al. 1992; eicken et al. 1995; reimnitz et al. 1995). these materials tend to melt out of the ice in the greenland and barents seas. here we investigate the temporal and spatial variation of shore-fast ice extent in the northeastern kara sea during 1953–1990 and its sensitivity to annual and interannual variation in climatic conditions in the study area. the years 1979 and 1985, which showed opposite scenarios of shore-fast ice development over the course of the cold season, are considered in detail. the area under study is in the north-eastern kara sea, east of the “line” between dikson island and zhelaniya cape (the northern tip of novaya zemlya), and south of the “line” connecting the zhelaniya cape and the northern extremity of the severnaya zemlya archipelago (fig. 1). data sets regular observations by the arctic and antarctic research institute (aari), in st. petersburg, during 1953–1990 provide data on fast ice extent (fetterer & troisi 1997). the data set is mainly based on gridded ice reconnaissance charts derived from observations from aircraft, and visible and infrared satellite imagery. the data’s spatial resolution (pixel size) is 12.5 km. the temporal data coverage is one survey a month during april to september 1953–1966. since 1966 the number of surveys has been three per month in the period of navigation from june to september. in 1980–1990 there were three observations each month, year-round. each survey is attributed to one of three 10-day periods of the month when the survey was made. the total number of surveys exceeds 500. when locating the fast ice border, the data precision lies within one pixel, according to the aari estimates. monthly means of surface air temperature (arctic climatology project 2000), snow depth and totals of the precipitation rate (groisman et al. 1998) recorded by meteorological stations located in the study area are used to assess the infl uence of atmospheric conditions on fast ice. the 3h time record of the wind strength and direction for dikson island is used to estimate the infl uence of wind stress on fast ice extent. daily averages of sea level pressure on a 2.5° latitude/longitude grid were derived from the 6h data provided by the national centers for environmental prediction, camp springs, md. monthly means of the fl ow rates of the ob and enisey rivers, acquired during 1950–1987, are used in the present study as well (martin & munoz 1995). we also used the twicefig. 1. topography of the kara sea. the locations of meteorological stations referred to in the paper are numbered: (1) dikson island; (2) izvestiy zik island; (3) sterlegova cape; (4) isachenko island; (5) pravdy island; (6) russkiy island; (7) geyberga island; (8) krasnophlotskie island; (9) golomyannyy cape; and (10) uedineniya island. the dotted line marks the study area. two extreme extents of fast ice in the kara sea in april are shown: the extent in 1979 (dashed line) was especially large, while in 1985 (solid line) it was especially small. 29divine et al. 2003: polar research 22(1), 27–34 daily northern hemisphere extratropical cyclone data set (serreze 1996) to analyse cyclone activity in the study area in the winters of 1979 and 1985. results analysis of aari data shows that shore-fast ice extent in the north-eastern kara sea varies signifi cantly from year to year. for example, in 1979 the area of fast ice in the north-eastern kara sea was as high as 125 000 km2 and in april 1985 it was as low as 58 000 km2. figure 2a c show time series of fast ice area in march, april and may. results of the linear regression analysis are imposed on each fi gure together with a 5-year running mean. all linear trends show decreases in the area of fast ice. the magnitudes of trends and relative decrease in the mean fast ice area in 1988–1990 compared to 1953–55 are presented in table 1. the value of the relative decrease in april is close to the error interval in determination of fast ice area, which is about 6.5 % according to the aari estimates. more observations are required for march and may to assess the statistical signifi cance of the trends. a prominent feature of fast ice regime in the kara sea is a bimodality of fast ice area noted by borodachev et al. (2000). figure 3 shows histo grams of fast ice area in the northeastern kara sea for spring months. two modes, with areas of about 90 000 110 000 km2 and 120 000 130 000 km2, are distinguished. together they cover about 55 % of observations during 1953–1990. table 2 shows correlations between the average winter surface air temperature anomalies and the anomalies of fast ice area in may. we defi ne the average winter air temperature for each cold season as an arithmetic mean of air temperature monthly means during september–april. coeffi cients were calculated for 10 meteorological stations located in the study area. the air temperature anomalies at each station were normalized by division of each monthly mean temperature by the multi-year mean (1950–1990) standard deviation for the given month. all correlations are signifi cant and close to –0.55. april shows similar results. to investigate the spatial variability of the average winter air temperature, correlations were calculated among all stations. the average win ter temperatures are highly correlated over table 1. results of linear trend analysis for the area of fast ice in spring. the third column is a relative decrease of mean fast ice area in 1953–55 compared to 1988–1990. month trend magnitude relative decrease (km2*year -1) of fast ice area (%) march –170 7 april –440 12 may –300 10 fig. 2. mean area of fast ice in the north-eastern part of the kara sea (a) in march, (b) april and (c) may during 1953–1990. the linear fi ts (long dashed lines) and 5-year running average (short dashed lines) are superimposed on each fi gure. (a) (b) (c) year 30 variability and climate sensitivity of fast ice extent the whole region. the correlation coeffi cients lie in the range 0.8 0.9. with correlation coeffi cients approaching 0.95 0.99, time series of mean monthly air temperatures correlate even more strongly than seasonal means. this shows that the temperature anomaly is stable across the entire north-eastern kara sea. we therefore conclude that the area of fast ice in april and may in this region correlates—with a value close to –0.55—with winter temperature. no signifi cant correlations were found between fast ice extent and cumulative winter precipitation or with average winthertime snow depth. analysis of the sensitivity of fast ice extent in april– may to the wind direction points to the signifi cant role of eastward and north-eastward winds in fast ice development during the winter season (september–april). this relationship has a correlation coeffi cient of –0.5. a weaker, but still signifi cant, correlation of about 0.4 characterizes the sensitivity of fast ice extent to westward and north-westward wind transport during the cold season. this indicates that prevailing westward wind transport across the north-eastern kara sea creates favourable conditions for shore-fast ice expansion and the eastward wind tends to impede it. wind data analysis also indicates that winds from the north-east during june–july increases fast ice destruction while winds from the northwest tend to restrain it. this tendency decreases for stronger winds from these directions. no correlations were found between fast ice extent and the preceding summer river outfl ow rate. data analysis shows that discharge from the ob and enisey rivers is likely important in the outfl ow zone around 100 km of the rivers’ mouths, since fast ice tends to break up fi rst in these areas in the beginning of june. the years 1979 and 1985 are two examples of extreme formation of shore-fast ice in the northeastern kara sea. figure 4 shows time series of fast ice area during the 1978/79 and 1984/85 cold seasons. analysis of fig. 4 and the surveys for these years reveal that formation of a stable belt of fast ice along the shore of the taymyr peninsula were completed in 1984/85 with a delay of about 40 days compared to 1978/79. the most dramatic difference between the two scen arios is in march–april. signifi cant expansion of shore-fast ice occurred during the second half of march to the fi rst 10 days of april 1979, whereas the development of fast ice in the same period of 1985 is characterized by a two-stage break-up. in the fi rst stage, which occurred during the second and third 10-day periods in march, a partial break-up of fast ice occurred between russkiy island and the severnaya zemlya archipelago. in the second table 2. correlation coeffi cient (r) of average surface air temperature anomalies in september–april for different locations in the north-eastern kara sea and average fast ice area anomalies in may. the stations are enumerated as in fig. 1. station r (1) dikson island –0.57 (2) izvestiy zik island –0.60 (3) sterlegova cape –0.58 (4) isachenko island –0.51 (5) pravdy island –0.59 (6) russkiy island –0.56 (7) geyberga island –0.45 (8) krasnophlotskie islands –0.57 (9) golomyannyy cape –0.47 (10) uedineniya island –0.53 fig. 3. frequency distribution of shore-fast ice area in the north-eastern part of the kara sea in march, april and may 1953–1990. 31divine et al. 2003: polar research 22(1), 27–34 stage most of the fast ice between dikson and isachenko islands broke up; this took place in the second 10-day period in april. detailed analysis of the meteorological conditions in the reference periods was carried out to reveal the source of these differences. the temperature regimes at three locations in the study area (fig. 5) in the cold seasons of 1978/79 and the 1984/85 were rather different, elucidating the above-mentioned relationships between the ano malies of the surface air temperature and extent of shore-fast ice. the difference in mean monthly surface air temperature reaches 15 °c in the winter months. it should also be noted that if mean monthly surface air temperatures in 1985 are close or slightly above the climate means, the temperature regime in 1979 exhibits negative temperature anomalies reaching 10 °c below the average. wind regimes show different directions of wind transport as well (fig. 6). during september– march 1978/79 the prevailing surface wind direction at dikson island was between 80° 160° , which corresponds to a north-westward geostrophic wind, taking into account the tuning angle of about 25° (overland & davidson 1992). the wind regime in 1985 did not exhibit as clear a picture as that of 1979. the monthly mean wind direction changed between 100° and 260°, with an average during september–march close to 220°, which means that a south-westerly wind prevailed this year. one can expect in this case onshore ice drift from the western kara sea compressing on fast ice in the north-eastern part of the sea. the mean monthly sea level pressure maps (not shown) confi rm the surface wind data. a comparison of cyclone activity in the kara sea for these particular years has shown that it was nearly the same during september–february for both seasons. however, a rather signifi cant distinction arose in march–april. while cyclone activity diminished in march–april 1979, in 1985 fi ve cyclones traversed the study area. one can relate these facts to the observed events of shorefast growth and break-up. the most likely candidates inducing the partial break-ups of shore-fast in march–april 1985 are cyclones which tracked the north-eastern kara sea during 12 16 and 22 27 march, and 16 20 april. figure 7 shows sea level pressure fi elds averaged over the passage time and tracks of the cyclones. one can suggest that during the fig. 4. seasonal variability of fast ice area in the north-eastern kara sea in the 1978/79 and 1984/85 cold seasons. note that the time axis is rearranged to coincide with the freeze season. the number on the time axis accounts for the 10-day period starting from the beginning of october. fig. 5. mean monthly air temperature at dikson island, golomyannyy cape and russkiy island in the 1978/79 and the 1984/85 winter seasons. the time axis is rearranged to coincide with the freeze season. fig. 6. mean monthly values of wind direction at dikson island meteorological station during the 1978/79 and the 1984/85 winter seasons. the time axis is rearranged to coincide with the freeze season. 32 variability and climate sensitivity of fast ice extent fi rst stage two principal mechanisms of fast ice break-up took place: a rise in sea level during the passage of the cyclone, induced by an inverted barometer effect, and the water drag stress. proshutinsky et al. (2001) has shown that the variation in atmospheric pressure in winter accounts for the short-term sea level variability in the kara sea. borodachev (1998) has pointed to the key role played by cyclone passage in inducing sea level rise during the partial break-up of shore fast in the south-western part of the kara sea. the location of the break-up zone near severnaya zemlya—just where the western taymyr current encounters the steep coast of the archipelago (fig. 1) and where signifi cant current velocities (up to 100 cm/s) are observed (volkov et al. 2002)—suggests that these strong currents could also have played an important role in the partial break-up of fast ice which occurred during 10 30 march 1985. the second stage of the partial break-up was initiated by sea level rise during the passage of the cyclone across fast ice (fig. 7c). at the same time, the wind speeds registered at dikson island during these periods do not exceed 12 m/s, with average values of about 7.5 m/s and 4 m/s during the fi rst and second stages, respectively (fig. 8). this is close to or below the climate average for march and suggests that the role of the wind stress was diminished. in contrast to 1985, march–april 1979 was characterized by a total absence of cyclone activity in the study area. the area of the kara sea was controlled by the high pressure system, located to the north-east of severnaya zemlya (fig. 7d), which hinders the penetration of cyclones into the fig. 7. cyclone passage time-averaged sea level pressure in (a) 12–18 march, (b) 22–27 march and (c) 16–20 april of 1985. (d) mean sea level pressure during 10 march to 10 april 1979. straight lines show the track of the centre of the cyclonic system on the 47 × 51 octagonal grid. the date (dd.m) and cyclone central pressure (mb) is given in the subscription near the open circle designating the position of the system centre. numbers 1 and 2 in (b) denote the fi rst and second cyclones detected during the reference period. the thick grey solid and dashed lines denote the border of fast ice at the beginning and the end of the reference periods: 10–30 march 1985 (a, b), 10–30 april 1985 (c) and 10 march to 10 april 1979 (d). note that these lines are merged on (a) and (b) along most of the fast ice border, highlighting the zone of the partial break-up near the severnaya zemlya archipelago. (a) (b) (c) (d) 33divine et al. 2003: polar research 22(1), 27–34 kara sea and determines the north-westward offshore wind transport in the entire basin. the thickness of fast ice registered at several locations in the north-eastern kara sea shows a signifi cant positive anomaly during the whole winter of 1979 (borodachev 1998; volkov et al. 2002). at isachenko island, in particular, the ice thickness anomaly amouting to about +35 cm— close to the absolute maximum—lasted through march–may 1979. in contrast to 1979, the spatial distribution of ice thickness in april 1985 is a negative anomaly—about –50 cm—over the entire north-eastern kara sea (romanov 1995). simple estimates prove the weaker susceptibility of thicker fast ice to atmospheric forcing. an assessment of the impact of wind drag stress on fast ice shows that the critical wind velocity required for failure in 1985 is about 0.75 that for 1979. given the ca. 170 cm ice thickness for the study area by the end of april, the stretch of fast ice of about 100 km and the surface drag coeffi cient at the upper limit of 5*10-3, the estimations with formulas given in crocker & wadhams (1989) yield the values of the critical wind velocities for 1979 and 1985: about 30 and 23 m/s, respectively. if the fi rst number is on the very edge, the second one falls well within the range of wind velocities observed in the study area (see example for march in fig. 8). however, an assessment of the sensitivity of shore-fast ice to variation of sea level requires detailed study involving the model ling of the propagation of cycloneinduced surge over the area with complex topography. we assume that conclusions drawn for these two particular years can be extended over time. however, the number of surveys, especially before the middle of the 1970s, is insuffi cient to capture the variability of shore-fast ice extent on a synoptic time scale. however, the existing data do catch the variability of shore-fast ice in the north-eastern kara sea on monthly and interannual time scales. summary these results show that the extent of shore-fast ice in the north-eastern kara sea undergoes signifi cant variability on both seasonal and interannual time scales. the frequency distribution of fast ice area in the north-eastern kara sea in spring is bimodal. modes with larger (120 130 *103 km2) and smaller (90 110 *103 km2) areas are distinguished. the linear trends for the time record of shorefast ice area in spring show a decrease during 1953–1990. the average areas in march, april and may in 1988–1990, estimated from time series of the aari data, are approximately 7, 12 and 10 % lower than in 1953–1955. we explain these negative trends by the prevalence, since 1980, the mode with decreased fast ice area. among the examined hydrometeorological parameters that are the potential sources of fast fig. 8. relative frequency distribution of wind velocities registered at dikson island during the passage time of cyclones during (a) 12–18 march, (b) 22–27 march and (c) 16–20 april 1985 (dashed lines) and the multi-year average for these months (solid lines). (a) (b) (c) 34 variability and climate sensitivity of fast ice extent ice variability on the interannual time scale, the surface air temperature and wind direction exert the most infl uence. we found that the correlation between average winter temperature during october–april and fast ice extent in may is about –0.55. a similar relationship characterizes the negative role of westerly wind in fast ice development. the easterlies, in contrast, promote fast ice expansion. these two parameters account for nearly the 50 % of the variability of shore-fast ice in the study area. combined analysis of wind data and river discharge volume in summer did not yield evidence of any direct infl uence of river run-off on fast ice development following the cold season. the river discharge is likely important in estuaries, since fast ice starts to break up fi rst in these areas. the investigation of shore-fast variation in 1979 and 1985 revealed that cyclone activity during winter and spring might signifi cantly infl uence its fast ice development by inducing partial break-ups. unfortunately, the temporal resolution of the existing data is insuffi cient for the examination of this assumption over the whole time span covered by the present study. we speculate that the increased frequency of westerlies may serve as an index for the increased cyclone activity during winter and consequently the probability of partial break-ups. the increased frequency of winds from the east during winter, in contrast, may result in a decrease of the surface air temperature in the study area, stimulating the thickening of ice and the formation of new ice on the borders of fast ice. the examination of other parameters that might be responsible for the rest of the variability of shore-fast ice, such as water heat content in the beginning of the cold season or ice thickness and their spatial distribution, is problematic until the relevant data become publicly available. acknowledgements.—the norwegian research council supported this work (project no. 128087/730). the authors thank the two reviewers whose comments helped improve the manuscript, and s. divina for preparing figs. 1 and 7. we are also grateful to the acsys project for fi nancially supporting the participation of d. divine in the workshop on sea ice extent and the global climate system, toulouse, 15–19 april 2002. references arctic climatology project 2000: environmental working group arctic meteorology and climate atlas. f. fetterer & v. radionov (eds). boulder: national snow and ice data center. cd-rom. borodachev, v. e. 1998: l’ dy karskogo morya. (ice in the kara sea.) st. petersburg: gidrometeoizdat. borodachev, v. e., gudkovich, z. m., klyachkin, s. v. & smolyanitsky, v. m. 2000: fast ice conditions in the kara sea and possible reasons of interannual changes of fast ice area. in: transport and fate of contaminants in the northern seas. aari fi nal report. tromsø, norway: norwegian polar institute. crocker, g. b. & wadhams, p. 1989: breakup of antarctic fast ice. cold reg. sci. technol. 17, 61–76. dethleff, d., loewe, p. & kleine, e. 1998: the laptev sea fl aw lead—detailed investigation on ice formation and export during 1991/1992 winter season. cold reg. sci. technol. 27, 225–243. eicken, h., viehoff, t., martin, t., kolatschek, j., alexandrov, v. & reimnitz, e. 1995: studies of clean and sediment-laden ice in the laptev sea. rep. polar res. 176, 62–70. fetterer, f. & troisi, v. 1997: aari 10-day arctic ocean ease-grid sea-ice observations. boulder: national snow and ice data center. digital media. groisman, p., koknaeva, v., belokrylova, t. & sanina, a. 1998: former soviet union monthly precipitation archive, 1891–1993. digital media. boulder: national snow and ice data center. martin, s. & munoz, e. 1995: russian rivers data set. digital media. boulder: national snow and ice data center. overland, j. e. & davidson, k. l. 1992: geostrophic drag coeffi cients over sea ice. tellus 44a, 54–66. proshutinksy, a., pavlov, v. & bourke, r. h. 2001: sea level rise in the arctic ocean. geophys. res. lett. 28, 2237–2240. reimnitz, e., kassens, h. & eicken, h. 1995: sediment transport by laptev sea ice. rep. polar res. 176, 71–77. reimnitz, e., marincovich jr., l, mccormick, m. & briggs, w. m. 1992: suspension freezing of bottom sediment and biota in the northwest passage and implications for arctic ocean sedimentation. can. j. earth sci. 29, 693–703. romanov, i. p. 1995: atlas of ice and snow of the arctic basin and siberian shelf seas. new york: backbone publishing. serreze, m. c. 1996: arctic cyclone track data set (1966– 1993). boulder: national snow and ice data center. digital media. timokhov, l. a. 1994: regional characteristics of the laptev and the east siberian seas: climate, topography, ice phases, thermohaline regime, circulation. rep. polar res. 144, 15– 31. volkov, v. a., johannessen, o. m., borodachev, v. e., voinov, g. n., pettersson, l. h., bobylev, l. p. & kouraev, a. v. 2002: polar seas oceanography. an integrated case study of the kara sea. london: springer. zubov, n. n. 1945: l’ dy arktiki. (arctic ice.) moscow: izd. glavsevmorputi. (translated in 1963 by us naval oceanographic offi ce, springfi eld.) invited keynote address global change and the polar regions chris rapley, british antarctic survey the earth system consists of the solid planet, its atmosphere, oceans, ice and biota. these are coupled via a myriad of complex physical, chemical and biological processes, which occur over a vast range of scales of time and space. natural variability and evolution are intrinsic to the system’s behaviour. however, recent dramatic surges i n human population and economic activity have resulted in mankind becoming a new and potent agent of global-scale changes. for example, after 10000 years of relative stability, there is mounting evidence that human activities are causing global climatic change. in order to balance the often conflicting requirements of economic growth and environ mental protection, it is essential to understand the workings of the earth system and the workings of human society within it. this can only be achieved through the methodology of science. without science there can be no “sustainable develop ment.” although geographically remote. the polar regions feature centrally i n many of the key contemporary earth system issues. thus: the seasonal growth and decay of sea ice and snow has a profound influence on the albedo and radiative balance of the planet. snow/ ice-albedo feedback, in which the melting of sea ice or snow results in increased heat absorption. underlies the prediction by global climate models of enhanced polar warming. the strong positive temperature trend observed over the antarctic peninsula, and the associated much-publicized collapse of ice shelves, may be early manifestations of this. 0 the polar ice sheets, lake sediments and marine sediments contain invaluable information on past states of the earth system, providing crucial insights into its functioning. and the characteristics of “natural” change. palaeo data of various forms indicate that the physical climate has the capacity for sudden and dramatic jumps. the only plausible mechanism for such events involves changes in the thermohaline circulation of the ocean, which themselves implicate the polar deep bottom water formation. antarctic deep bottom water permeates beneath 40% of the world’s oceans, but its formation mechanisms and role are poorly understood. the mass balance of the ice sheets is critical, since any variations will have a significant impact on mean sea level, and hence on coastlines world-wide. the dynamics and temperature structure of the polar stratosphere are such that the region is especially prone to the destruction of the ozone layer by man-made chemicals such as cfcs. thus the “ozone hole” was first detected over antarctica, and remains especially strong there, in spite of the international legal instruments introduced to ban cfc production and usage. polar ecosystems tend to be simpler in structure than lower latitude systems, and their members exhibit many examples of specialized adapta tions. thus their study can provide fundamental insights. the southern ocean is one of the world’s most productive oceans and is a potentially major fishery. the research undertaken to guide the commission for the conservation of marine living resources (ccamlr) has adopted an ecosystem approach and lies at the forefront of its field. antarctica was the “hub” of the gondwana supercontinent. its study is essential if the mechanisms of continental break up and drift are to be fully understood. the convergence of magnetic field lines at the geographic poles provides the opportunity for the study of sun-earth interactions, which are important to understand the fundamentals of plasma magnetohydrodynamics, as well as being of practical value for radio communica tions and the design of robust satellite systems. 0 the geographic remoteness of the polar regions results in very low levels of man-made pollu rapley 1999: polar research / r ( 2 ) , i 17-1 18 1 i7 tion. nonetheless, pollutants can be detected there, providing a measure of the extent to which mankind is contaminating the planet. new opportunities for studying the polar regions and cryospheric processes are provided by upcom ing spacecraft from the usa, europe and japan, by the potential for greater coordination of existing national field stations and facilities, from advances in telecommunications technology, and from enhanced levels of international networking. satellite remote sensing offers a special contribu tion, although to fulfil its potential, this needs to be coupled with dedicated field work. the polar regions are hazardous to work in and costly to access. hence, international collabora tions are particularly valuable since they share costs, avoid unnecessary duplication and, through the establishment of a “critical mass”, permit issues to be addressed which transcend the capability of any one nation. examples include the projects organized by the international arctic science committee and the scientific committee on antarctic research in the area of global change. other international organizations, such as the world climate research programme and the international geosphere-biosphere programme, also address polar issues. the challenges facing the polar science com munity include: carrying out a review or “reality check” on priorities; rationalizing and strengthening research struc tures; strengthening and sustaining research net works; exploiting the new opportunities; synthesizing “understanding” from the plethora of results. this conference provides an excellent opportunity to hear the very latest results and to discuss and agree on specific priorities for the future. 118 global change and the polar regions doi:10.3402/polar.v32i0.19784 r e s e a r c h / r e v i e w a r t i c l e tintinnid ciliates of amundsen sea (antarctica) plankton communities john r. dolan,1 eun jin yang,2 sang hoon lee2 & sun young kim3 1 marine microbial ecology group, laboratoire d’océanographie de villefranche, pierre and marie curie university and the national center for scientific research centre (cnrs), umr 7093, station zoologique, b.p. 28, fr-06230 villefranche-sur-mer, france 2 division of polar climate research, korea polar research institute (kordi), songdo techno park, songdo, yeonsu, incheon 406�840, korea 3 department of oceanography, inha university, incheon 402�751, korea keywords zooplankton; microzooplankton; polynya; protists; phaeocystis; diatoms. correspondence john r. dolan, marine microbial ecology group, laboratoire d’océanographie de villefranche, université pierre et marie curie and the national center for scientific research (cnrs), umr 7093, station zoologique, b.p. 28, fr-06230 villefranche-sur-mer, france. e-mail: dolan@obs-vlfr.fr abstract the amundsen sea has been described as one of the most productive and dynamic pelagic systems in antarctica and is one of the least studied. based on samples from 15 stations in the amundsen sea, we describe for the first time the composition of the tintinnid ciliate assemblage of the microzooplankton. we compared the species compositions of coastal polynya sites, where the phytoplankton communities are dominated by phaeocystis, to those of the offshore deep water sites, which are dominated by diatoms. we found a total of 15 species. polynya sites were dominated by a few species of tintinnids, mostly those endemic to the southern ocean. in contrast, the deep-water sites contained many widespread tintinnid species, which are known from a wide variety of systems as well as other areas of the southern ocean. we examined polymorphism known to characterize the antarctic tintinnid species cymatocylis affinis/convallaria and codonellopsis gaussi. we found that the types or forms found appeared unrelated to the type of microplankton community, defined by the identity of the dominant phytoplankton taxa. however, the number of different morphotypes found at a site appeared related to the overall concentration of the species, suggesting that different morphologies, previously considered distinct species, may simply be developmental stages. the amundsen sea is a dynamic region of the antarctic. it was recently described as ‘‘one of the most rapidly changing parts of the cyrosphere’’ (smith et al. 2011) because it is receiving increasing amounts of meltwater from the west antarctic ice sheet and experiencing winter warming (ding et al. 2011). studies based on data from satellite images have concluded that coastal areas of the amundsen sea are among the most productive in antarctica (arrigo & van dijken 2003) and that primary production, perhaps fuelled in part by increases in iron input from glacier meltwater, may increase in the future (arrigo et al. 2012). paradoxically, the amundsen sea is also one of the most poorly sampled areas of the southern ocean (griffiths 2010; de broyer et al. 2011) and has but recently become a focus of attention in biological oceanography. primary production in the amundsen sea polynya is probably the most productive of any area in antarctica (yager et al. 2012). the amundsen sea polynya, dominated by the colonial haptophyte phaeocystis antarctica, may increase in relative importance in the future compared to the off-shore communities in which primary production is dominated by large diatoms (alderkamp et al. 2012). tintinnid ciliates are one of the many distinct groups of organisms that make up the marine microzooplankton, the functional group of organisms nominally between 20 and 200 mm in maximal dimension, which are grazers feeding primarily on small phytoplankton sizes ranging from 2 to 20 mm. in most pelagic systems*including different areas of the southern ocean (calbet & landry 2004)*the microzooplankton are recognized to be the major consumers of primary production, accounting for (page number not for citation purpose) polar research 2013. # 2013 j.r. dolan et al. this is an open-access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 the consumption of about 70% of daily production. exceptions to this general rule are when primary production is dominated by large diatoms or phaeocystis, as is often the case in productive southern ocean waters (e.g., burkill et al. 1995; tsuda & kawaguchi 1997; caron et al. 2000; froneman 2004). compared to oligotrich ciliates or heterotrophic dinoflagellates, tintinnids are generally a minority component of the microzooplankton (e.g., dolan et al. 1999). however, there are records of tintinnids acting as the dominant consumers of phytoplankton (e.g., karayanni et al. 2005). the major predators of tintinnids are usually thought to be copepods although a wide variety of animals are known to consume tintinnids (stoecker 2012). while there are no data from the amundsen sea, in other southern ocean systems, gut contents studies have shown that tintinnids are eaten by a variety of both pelagic and benthic organisms. tintinnid loricae have been found in the guts of crustacean zooplankters such as copepods (lonsdale et al. 2000; kruse et al. 2009), krill and mysid shrimp (mauchline 1980), the zooplankters usually considered the major consumers of microzooplankton (e.g., froneman et al. 1996). however, other southern ocean animals, many not often thought of as predators of microzooplankton, have been found to contain the remains of tintinnids. these include the larger gelatinous zooplankton such as salps (buck et al. 1992), chaetognaths (hopkins 1987) and larval antarctic silverfish (pleuragramma antarcticum; kellermann 1987). some benthic organisms of the antarctic, such as octocorals (orejas et al. 2003) and deep sea isopods (brökeland et al. 2010), have been found to contain the remains of tintinnids. in the southern ocean, tintinnids appear to be a widely exploited resource. unlike the numerically dominant taxa of the microzooplankton, the oligotrichid ciliates and heterotrophic dinoflagellates, tintinnids have species-specific shells or loricae. hence, species identifications are relatively straightforward, unlike most microplankton taxa. generally, the tintinnid lorica is tubular or conical but a very large range of constructions is found among the different taxa. the diameter of the open mouth-end of the lorica, the lorica oral diameter (lod), is an important characteristic not only in terms of taxonomy but it is also a key ecological characteristic. a given species feeds at a maximum rate on prey of a size of about 25% of lod (dolan 2010). in common with other protistan taxa with skeletal structures or shells, the characteristics of such hard parts are used to define species despite the fact that some tintinnid species are known to display considerable plasticity in lorica morphology (e.g., laval-peuto & brownlee 1986). indeed, some antarctic taxa have long been suspected of showing morphological plasticity. the existence of intermediate forms morphologies described as distinct species led to the suggestion that cymatocylis species may be polymorphic (boltovskoy et al. 1990; williams et al. 1994) as well as the species codonellopsis gaussi (alder 1999). recent genetic studies have confirmed the suspected polymorphism of cymatocylis affinis/convallaria and codonellopsis gaussi (kim et al. in press). the factors that may be associated with the different morphologies or forms remain completely unknown. in late 2010, the maiden voyage of the ice-breaker araon provided the opportunity to make the first direct measurements of primary production in the amundsen sea along with analysis of phytoplankton composition (lee et al. 2012). during the cruise, the stations sampled included both polynya and open-water stations. material was obtained at 15 stations using a 20-mm plankton net for the analysis of the microplankton community (fig. 1). to our knowledge, this is the first report on the ecology and species composition of tintinnids of the amundsen sea. the only existing data are part of the total ciliate species inventory from the study of wickham et al. (2011), who provided a species list pooled from several bellinghausen and amundsen sea stations, and the recent study of morphology and phylogeny of selected taxa by kim et al. (in press). here, we present data on the composition and distribution of the tintinnid assemblage of the amundsen sea. we sought to determine if the tintinnid assemblages found in the non-polynya stations, primarily open deep waters, in which the microplankton community is dominated by diatoms, differed from those found in the coastal polynya stations, fig. 1 location of stations sampled for tintinnids. the green box distinguishes the polynya stations (following lee et al. 2012). tintinnid ciliates of the amundsen sea j.r. dolan et al. 2 (page number not for citation purpose) citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 dominated by phaeocystis. we also sought to determine if different forms or morphotypes of the polymorphic species cymatocylis affinis/convallaria and condonellopsis gaussi co-occur or are found in different microplankton communities. here, we use the name cymatocylis affinis/ convallaria to remain in conformity with the existing literature (e.g., boltovskoy et al. 1990; wasik & mikolajszyk 1994). materials and methods the data reported were collected during the cruise of the korean research ice-breaker araon in the amundsen sea from december 2010 to january 2011. a niskin bottle rosette equipped with conductivity*temperature* density probes was used to sample a total of 30 stations and plankton net tows were performed to assess microplankton community composition at 15 of the 30 stations sampled (fig. 1). stations were located in both deep offshore waters and polynya areas, considered as coastal areas of open water (free of sea ice) within the sea ice zone; areas of sea ice and concentrations were based on data from the national snow and ice data center in boulder, colorado, corresponding to the cruise period. the classification of stations used here follows that established in lee et al. (2012). for chlorophyll a determinations, water samples of 0.3�1 l were obtained from 7 to 9 discrete depths between the surface and 150 m depth. water samples were filtered through a 0.7-mm grade gf/f glass fibre filter (whatman, kent, uk) and chlorophyll concentrations were determined on-board using a trilogy fluorometer (turner designs, sunnyvale, ca, usa) calibrated against commercial chl a standards. net tows were made with a 20-mm plankton net, 0.45 m in diameter, equipped with a calibrated flowmeter, towed from 150 m depth to the surface. a portion of the net tow material was fixed with bouin’s solution (6% final concentration) for direct microscopic examination. in the laboratory, aliquots of net tow material were sequentially diluted and examined in settling chambers using an inverted microscope equipped with differential interference contrast optics. the entire surface of the settling chamber was examined at 200 � total magnification. species identifications were made using the monographs of kofoid & campbell (1929, 1939), hada (1970), balech (1973) and alder (1999). total sample volumes examined varied, depending on the concentrations of tintinnids and the dilutions employed varied according to concentrations of phytoplankton. however, multiple aliquots were examined until at least 50 tintinnids were enumerated for each station (tintinnids enumerated per station ranged from 52 to 358; average 1729139). the sample volumes examined were equal to 1�7 ml of the original 350 ml total net tow material, representing material from about 10�400 l filtered by the net. nominal concentrations of organisms were calculated based on the apparent volume filtered by the net (as indicated the by net flowmeter) and the volume of net tow material examined. it should be noted that the concentrations reported here are the average values per litre for the top 150 m of the water column. in general, relatively few cells are found below the mixed layer (e.g., dolan & marassé 1995). consequently, the table 1 locations and physical characteristics of the sample stations (see also fig. 1). numbers in boldface denote polynya stations and one marginal polynya station (station 8), which was not completely free of sea ice. station type, mixed layer and euphotic zone depth from, and methods described by lee et al. (2012). station lat. long. date depth sea ice (%) mixed layer depth (m) euphotic layer depth (m) 1 63.99 108.99 12/26/10 4990 0 21 45 2 65.69 111.26 12/27/10 4838 0 12 60 4 68.47 116.74 12/28/10 4000 0 13 70 5 70.00 120.02 12/29/10 2900 50�60 13 60 6 71.95 119.13 12/30/10 1451 50�60 18 nd 7 72.41 117.69 12/31/10 530 30�40 15 54 8 72.83 116.48 12/31/10 640 10 22 nd 9 73.25 115.00 01/01/11 1050 0 54 50 18 73.00 113.50 01/06/11 448 0 20 20 21 73.50 116.50 01/06/11 376 0 25 nd 22 72.45 120.14 01/07/11 1360 60�70 16 nd 26 71.49 116.95 01/08/11 1364 70�80 22 nd 27 69.00 120.50 01/11/11 1140 0 20 40 28 68.00 120.00 01/11/11 4300 0 12 nd 29 67.00 120.00 01/12/11 4520 0 12 25 30 64.91 131.27 01/13/11 4820 0 14 70 j.r. dolan et al. tintinnid ciliates of the amundsen sea citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 concentrations of cells in the mixed layer were likely several times higher than those reported here, which represent the entire 150 m water column. for several stations, we also enumerated copepod nauplii as a proxy measure of copepod abundance. simple linear regression was used to investigate the relationships between concentrations (log transformed) of tintinnids and chlorophyll as well as occurrences of different morphotypes. table 2 biological characteristics of the stations. the primary production data (14c-based) are from table 2 in lee et al. (2012), estimated at a few of the stations sampled for microplankton. microphytoplankton composition, based on examination of net tow material, was clearly dominated by either diatoms (d), phaeocystis (p) or mixture of both (d/p). tintinnid concentrations and number of species are shown for the top 150 m of the water column. values in boldface denote data corresponding to polynya stations or near polynya conditions (station 8). station no. avg chl (mg l�1)a max chl (mg l�1)b z chl max (m)c avg pp (mg carbon l�1 h�1)d microphytoplankton copepod nauplii tintinnids (cells l�1) no. spp. 1 0.4 0.8 40 � d/p � 4.9 7 2 0.3 0.5 55 � d � 9.8 7 4 0.2 0.3 80 0.009 d � 5.5 4 5 0.2 0.3 60 0.054 d � 0.1 4 6 0.3 0.6 35 � d/p � 1.3 7 7 0.6 1.8 20 0.327 d � 3.2 6 8 1.6 5.2 15 � p 0.5 2.4 4 9 5.6 11.9 10 3.500 p � � 2 18 2.5 12.2 5 1.935 p 1.2 5.4 4 21 4.1 11.4 5 � p 0.9 7.3 4 22 0.4 1.0 25 � d/p � 7.2 5 26 0.2 0.4 30 0.028 d � 4.3 5 27 0.3 0.4 70 � d 0.8 1.1 5 28 0.2 0.4 5 � d 1.9 8.8 4 29 0.3 0.7 10 � d 0.3 2.6 7 30 0.4 1.1 27 0.176 d � 6.5 10 a average chlorophyll in integrated throughout the top 150 m of the water column. b the maximum concentration of chlorophyll. cdepth of the chlorophyll maximum. dprimary production integrated throughout the euphotic zone (see table 1 for euphotic zone depth). fig. 2 water column profiles of (a, b) station 5, typical of deep off-shore stations, and (c, d) a polynya station, station 18. note the difference in scales of the chlorophyll profiles. for further details see tables 1 and 2. tintinnid ciliates of the amundsen sea j.r. dolan et al. 4 (page number not for citation purpose) citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 results the physical and biological characteristics of the offshore deep water stations differed considerably from those of the coastal polynya stations. the polynya stations, compared to the non-polynya, primarily offshore sites, were characterized by shallower mixed layer depths (table 1), considerably higher chlorophyll a concentrations with a distinct chlorophyll maximum, and high primary production (table 2, fig. 2). the offshore stations were comparatively low in concentrations of chlorophyll and showed more even vertical distributions of chlorophyll. the phytoplankton dominating the microplankton communities was distinctly different also. in the deep water offshore stations, the microplankton was dominated by diatoms while in the polynya stations, microplankton was dominated by phaeocystis (table 2, fig. 3). it should be noted that our observations concerning fig. 3 low magnification (4 � objective) views of settled net tow material from (a) an offshore deep-water station, station 5, showing a dominance by diatoms, and (b) a coastal polynya station, station 18, showing a dominance by colonies of phaeocystis. the area shown is equivalent to a volume of the original net tow material from about 1 l of seawater. the arrows show tintinnids (cymatocylis). table 3 species records for each station with the station numbers in boldface denoting the polynya stations or near polynya conditions (station 8). the distributional type is based on the biogeographic classifications presented by dolan et al. (2012). note that most species were absent from the polynya stations. the species found in polynya were exclusively the southern ocean endemic forms except for salpingella faurei. note that the species codondellopsis gaussi and cymatocylis convallaria group forms previously considered separate species in some reports. species station occurrence distributional type acanthostomella obtusa 1, 2 widespread amphorellopsis laevis 27 widespread amphorellopsis quinqueala 1, 26, 7, 22, 26, 29, 30 southern ocean amphorides laackmanni 29 widespread codonellopsis gaussi 1, 2, 4, 5, 6, 7, 18, 21, 26, 28, 29, 30 southern ocean codonellopsis gaussi f. cylindroconica 1, 2, 4, 5, 6, 18, 27, 28, 29, 30 southern ocean codonellopsis gaussi f. coxiella 6 southern ocean codonellopsis gaussi f. globosa 30 southern ocean codondellopsis pusilla 2, 30 widespread cymatocylis convallaria f. affinis 1, 2, 5, 6, 7, 8, 9, 18, 21, 22, 26, 28 southern ocean cymatocylis convallaria f. calcyformis 1, 2, 26, 30 southern ocean cymatocylis convallaria f. cylindrica 1 southern ocean cymatocylis convallaria f. drygalski 1, 2, 5, 6, 7, 8, 9, 18, 21, 22, 26, 29 southern ocean cymatocylis convallaria f. subrotundata 18 southern ocean cymatocylis parva 1, 2, 6 southern ocean epiplocycloides reticulata 1, 8, 21 widespread laackmanniella navaecula 4, 6 southern ocean laackmanniella prolongata 2, 4, 5, 6, 7, 8, 9, 18, 21, 22, 26, 27, 28, 29, 30 southern ocean salpingella curta 6 widespread salpingella decurtata 29, 30 widespread salpingella faurei 1, 4, 5, 6, 7, 8, 18, 21, 22, 26, 27, 28, 29, 30 widespread salpingella laackmaniella 7, 22, 27 widespread j.r. dolan et al. tintinnid ciliates of the amundsen sea citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 fig. 4 tintinnid species encountered in the amundsen sea samples. (a) salpingella laackmanni, (b) salpingella decurtata, (c) salpingella faurei, (d) laackmanniella naviculaefera, (e) laackmanniella prolongata, (f) amphorellopsis quinquelata, (g) amphorides laackmanni, (h) acanthostomella obtusa, (i) codonellopsis pusilla, (j) epiplocylcoides reticulata; (k) codonellopsis gaussi, (l) codonellopsis gaussi, (m) codonellopsis gaussi forma globosa, (n) codonellopsis gaussi forma cylindricoconica, (o) condonellopsis gaussi forma coxiella, (p) cymatocylis affinis/convallaria, (q) cymatocylis affinis/ convallaria forma calcyformis, (r) cymatocylis affinis/convallaria forma subrotundata, (s) cymatocylis affinis/convallaria forma drygalski and (t) cymatocylis affinis/convallaria forma cylindrica. note that some species agglutinate diatoms; the diatoms are not necessarily the most abundant according to wasik et al. (1996). tintinnid ciliates of the amundsen sea j.r. dolan et al. 6 (page number not for citation purpose) citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 phytoplankton composition refer to the microplankton community, not the entire phytoplankton community. a total of 15 species with a wide range of morphologies were encountered in the samples, as well as a variety of morphotypes of two antarctic species, codonellopsis gaussi and cymatocylis affinis/convallaria (table 3, fig. 4). typically, low species-richness (two to four species) characterized the polynya assemblages compared to the non-polynya assemblages (4�10 species). furthermore, polynya assemblages were generally dominated by species endemic to the southern ocean (largely forms of cymatocylis affinis/convallaria and condonellopsis gaussi) while the offshore assemblages included many widespread tintinnid taxa (table 3). overall, the abundance of tintinnids was clearly not related to bulk chlorophyll concentrations (table 2). however, plotting chlorophyll data by the dominant type of phytoplankton (diatom, phaeocystis, or both) suggested that within phaeocystis-dominated communities, tintinnid abundance increased with chlorophyll concentrations (fig. 5). note that we have no data on the abundance of nano-phytoplankton such as the single-cell forms of phaeocystis or other probable major prey items for tintinnid ciliates. we found no clear relationship between the composition of the microphytoplankton and the occurrence of different morphologies of condonellopsis gaussi and those of cymatocylis affinis/convallaria. of the many different ‘‘forms,’’ or morphotypes, encountered (fig. 4), most were found in both the diatom-dominated offshore stations and the phaeocystis-dominated polynya stations (table 3). there was also no relationship between the number of morphotypes co-occurring and the concentration of chlorophyll, regardless of the identity of the taxa dominating the phytoplankton. however, there was a weak but significant positive relationship between the number of different morphotypes found in an assemblage and the overall concentration of c. affinis/convallaria (fig. 6). there was also a positive trend between the numbers of c. gaussi morphotypes or forms found and the overall concentration of c. gaussi but not a significant linear relationship. discussion we documented a species-richness for the amundsen sea far in excess of that known for the adjacent bellinghausen sea (table 4). there is no doubt that our results reflect the fact that we examined material from large volumes of water sampled with a relatively fine-mesh net. interestingly, most (nine out of the 15 species) were ‘‘widespread’’ species, found in a variety of systems ranging from the mediterranean sea (dolan 2000) to the pacific ocean (dolan et al. 2007), and all were species which have been previously recorded from other southern ocean locations, if not the bellinghausen sea (see dolan et al. 2012). therefore, none of our species records for the amundsen sea are new for the southern ocean. however, we did establish for the first time the existence of distinct tintinnid communities in polynya and offshore deep water based on our data concerning the amundsen sea. at the polynya stations, where the microplankton community was dominated by phaeocystis, the tintinnid assemblage was a particular subset of the species catalogue. only four species were found and three of the four are species endemic to the southern ocean: cymatocylis affinis/convallaria, codonellopsis gaussi, laackmanniella prolongata. these southern ocean species are all relatively wide-mouth species, with lods measuring from 40 to 100 mm, presumably feeding most efficiently on prey much larger than those exploited by most of the other species found in the amundsen sea (see fig. 4). while fig. 5 scatterplot showing relationship between tintinnid and chlorophyll concentrations in the top 150 m. symbols distinguish stations in which the microphytoplankton was dominated by diatoms, phaeocystis, or was a mixture of both. there was no significant relationship between tintinnid and overall chlorophyll concentration or among stations in which diatoms dominated the microplankton community. while we have quantitative data for only three of the four polynya stations, the concentration of tintinnids does, however, appear to increase with chlorophyll concentrations in the phaeocystis-dominated communities (n �3, r �0.987). j.r. dolan et al. tintinnid ciliates of the amundsen sea citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 there were few data points, it was only among the polynya stations that there appeared to be a relationship between the concentrations of chlorophyll and tintinnids (fig. 5). however, it is unclear if the relationship could reflect a predator*prey relationship between phaeocystis and tintinnids. typical planktonic ciliates, such as oligotrichs are unable to graze on colonies of phaeocystis and ingest only the individual free-swimming cells (e.g., verity 2000). however, tintinnids can reportedly ingest cells from the outer layer of colonies of phaeocystis, crop individual cells, as well as feed on the free-swimming stage (admiraal & venekamp 1986). an alternative, but not exclusive, explanation for a positive relationship between phaeocystis concentration and tintinnid abundance is that predation on tintinnids is lower in such communities due to either lower predator abundance or lower predator feeding efficiency with increasing concentrations of phaeocystis. many polynya areas are known to be characterized by the relatively low abundance of zooplankton (e.g., tagliabue & arrigo 2003) and this appears to be the case for amundsen sea polynya also (yager et al. 2012). we do not have data on the abundance of predators of tintinnids in our polynya compared to non-polynya stations, only some indirect evidence in the form of copepod naupliar concentrations. our data on copepod nauplii abundance (table 2) suggests little difference between polynya stations and off-shore stations. however, this is weak evidence of no difference in top*down control of tintinnid composition. regardless of the fig. 6 scatterplots showing the relationship between the numbers of different forms of (a) cymatocylis affinis and (c) condonellopsis gaussi found in relation to the concentration of chlorophyll (symbols show the dominant phytoplankton forms), and (b, d) the total concentrations of the species, all forms pooled. note that there is no apparent relationship between numbers of forms and the concentration or composition of the phytoplankton. however, the number of forms found in a station sample was positively related to the overall concentration of cymatocylis affinis, all forms pooled. for c. gaussi the relationship was not significant. tintinnid ciliates of the amundsen sea j.r. dolan et al. 8 (page number not for citation purpose) citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 mechanism influencing tintinnid species composition found in phaeocystis-dominated sites, the projected increase in the relative importance of phaeocystis in the amundsen sea (alderkamp et al. 2012) may be accompanied by increases in the relative importance of the endemic antarctic species (i.e., cymatocylis, laackmaniella) at the expense of the widespread species found in the diatom-dominated microplankton communities. we were also interested in examining the phenomenon of polymorphism in the species cymatocylis affinis and codonellopsis gaussi (fig. 4). our working hypothesis was that distinct morphologies represent adaptations to distinct conditions. however, we found no evidence that particular morphologies are associated with particular phytoplankton communities. a near full-range of morphologies was found in microplankton communities dominated by diatoms as well as communities dominated by phaeocystis (table 3). the number of morophotypes found in individual samples was also unrelated to the number of cells enumerated (data not shown). also, the number of different morphologies found in an assemblage appeared unrelated to the concentration of chlorophyll, regardless of the type of phytoplankton assemblage (fig. 6a, c). an alternative explanation for polymorphism is that rather than representing adaptations to a particular environment, the different morphologies found are simply different developmental stages. in this regard, it should be noted that in tintinnids, which reproduce by cell division, the lorica is retained by the newly formed daughter cell, the opisthe, and the cell with the parental mouth, the protor, swims off and forms a new lorica (see agatha et al. 2012). consequently, in a population of tintinnids there are both ‘‘old’’ and ‘‘new’’ loricas. the loricas inhabited by many of the tintinnids in a population were formed not by the current inhabitants but rather by ancestral cells and not necessarily direct ancestors but possibly several generations removed. we speculate that a population of tintinnids, if it is relatively long-lived and experiences rapid bursts of population growth, is liable to contain loricas formed by cells which divided before lorica formation was complete. these partially formed loricas could be retained in the population, inherited by successive generations. unfortunately, we cannot directly examine this possibility. however, if polymorphism simply reflects different developmental stages, we reasoned that dense populations would exhibit more polymorphism than sparse populations as dense populations are more likely to show characteristics of rapid population growth and thus contain more ‘‘immature individuals’’ corresponding to different morphotypes or forms. we found some evidence in support of the hypothesis as the concentration of cymatocylis affinis/convallaria was positively related to the number of morphotypes in the population (fig. 6b). a positive (although not significant) trend was also table 4 species records of the amundsen sea and the adjacent bellinghausen sea. species names in boldface are endemic to the southern ocean; the others are known from a wide range of areas including other regions of the southern ocean (dolan et al. 2012). species now known to be forms or morphological variants of cymatocylis affinis/convallaria and variants of condonellopsis gaussi (see table 3) are not listed separately. species bellinghausen sea amundsen sea bellinghausen/amundsen acanthostomella obtusa this report amphorellopsis laeva this report amphorellopsis quinquealata balech 1973 kim et al. in press; this report amphorides laackmanni this report wickham et al. 2011 codonellopsis balechi balech 1973 codonellopsis biedermanni wickham et al. 2011 codenellopsis gaussi balech 1947, 1973; alder & boltovskoy 1991 kim et al. in press; this report codonellopsis pussila this report cymatocylis affinis/convallaria balech 1947, 1973; sassi & melo 1986; barria de cao 1987 kim et al. in press wickham et al. 2011 cymatocylis parva this report epiplocycloides reticulta this report helicostomella subulata wickham et al. 2011 laackmanniella naviculaefera balech 1973, sassi & melo 1986; barria de cao 1987; alder & boltovskoy 1991 this report laackmanniella prolongata balech 1947; alder & boltovskoy 1991 kim et al. in press; this report salpingella curta this report salpingella decurtata this report salpingella faurei this report salpingella laackmaniella this report j.r. dolan et al. tintinnid ciliates of the amundsen sea citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 apparent in condonellopsis gaussi (fig. 6d). note that these trends were not dependent on the overall number of individuals examined for each station. conclusion we found a high species-richness in the amundsen sea compared to the better known adjacent bellinghausen sea. we compared, for the first time, the species assemblages of coastal polynya sites, projected to increase in relative importance in the future, with offshore deep water sites. the polynya sites of high primary production dominated by phaeocystis, show a lower species richness and are formed mainly of large-mouthed tintinnid species endemic to the southern ocean. in the polymorphic species cymatocylis affinis/convallaria and codonellopsis gaussi, the number of types or forms found co-occurring appeared related to the overall concentration of the species, suggesting that the different morphologies may simply be developmental stages. acknowledgements support for this work was provided by the korea polar research institute through its pp12010 project as well as by the french national center for scientific research, the university of paris 6 and the aquaparadox project, financed by the french national research agency programme biodiversite? and by pôle mer paca. the thoughtful comments of the reviewers and steve wickham are gratefully acknowledged. references admiraal w. & venekamp l.a.h. 1986. significance of tintinnid grazing during blooms of phaeocystis pouchetii (haptophycaea) in dutch coastal waters. netherlands journal of sea research 20, 61�66. agatha s., laval-peuto m. & simon p. 2012. the tintinnid lorica. in j.r. dolan et al. (eds.): the biology and ecology of tintinnid ciliates: models for marine plankton. pp. 17�41. oxford: wiley-blackwell. alder v.a. 1999. tintinnoinea. in d. boltovskoy (ed.): south atlantic zooplankton. vol. 1. pp. 321�384. leiden: backhuys publishers. alder v.a. & boltovskoy d. 1991. the ecology and biogeogeography of tintinnid ciliates in the atlantic sector of the southern ocean. marine chemistry 35, 337�346. alderkamp a.-c., mills m.m., van dijken g.l., laan p., thuroczy c.-e., gerringa l.j.a., de baar h.j.w., payne c.d., visser r.j.w., buma a.g.j. & arrigo k.r. 2012. iron from melting glaciers fuels phytoplankton blooms in the amundsen sea (southern ocean): phytoplankton characteristics and productivity. deep-sea research part ii 71�76, 32�48. arrigo k.r., lowry k.e. & van dijken g.l. 2012. annual changes in sea ice and phytoplankton in polynyas of the amundsen sea, antarctica. deep-sea research part ii 71�76, 5�15. arrigo k.r. & van dijken g.l. 2003. phytoplankton dynamics within 37 antarctic coastal polynya systems. journal of geophysical research*oceans 108, article no. 3271, doi: 10.1029/2002jc001739. balech e. 1947. contribucion al conocimiento del plancton antartico. plancton del mar de bellingshausen. (contribution to our knowledge of antarctic plankton. the plankton of the bellinghausen sea.) physis, buenos aires 20, 75�91. balech e. 1973. segunda contribucion al conocimiento del plancton del mar de bellingshausen. (second contribution to our knowledge of the plankton of the bellinghausen sea.) contribucion del instituto antartico argentino 107, 3�63. barria de cao m.s. 1987. tintinnia (protozoa, ciliata) de la zona antarctica argentina. (tintinnids (protozoa, ciliata) of the argentine antarctic zone.) in: primer symposium espanol de estudios antarcticos. (first spanish symposium on antarctic studies.) pp. 275�284. madrid: spain in the antarctic society, high council for scientific research. boltovskoy d., dinofrio e.o. & alder v.a. 1990. intraspecific variability in antarctic tintinnids: the cymatocylis affinis/ convallaria species group. journal of plankton research 12, 403�413. brökeland w., guomundsson g. & svavarsson j. 2010. diet of four species of deep-sea isopods (crustacea: malacostraca: peracarida) in the south atlantic and the southern ocean. marine biology 157, 177�187. buck k.r., garrison d.l. & hopkins t.l. 1992. abundance and distribution of tintinnid ciliates in an ice edge zone during the austral autumn. antarctic science 4, 3�98. burkill p.h., edwards e.s. & sleigh m.a. 1995. microzooplankton and their role in controlling phytoplankton growth in the marginal ice zone of the bellingshausen sea. deep-sea research part ii 42, 1277�1290. calbet a. & landry m.r. 2004. phytoplankton growth, microzooplankton grazing, and carbon cycling in marine systems. limnology and oceanography 49, 51�57. caron d.a., denett m.r., lonsdale d.j., moran d.m. & shalapyonok l. 2000. microzooplankton herbivory in the ross sea, antarctica. deep-sea research part ii 47, 3249�3272. de broyer c., danis b. & 64 scar-marbin taxonomic editors. 2011. how many species in the southern ocean? towards a dynamic inventory of the antarctic marine species. deep-sea research part ii 58, 5�17. ding q., steig e.j., battisti d.s. & küttel m. 2011. winter warming in west antarctica caused by central tropical pacific warming. nature geoscience 4, 398�403. dolan j.r. 2000. tinitinnid ciliate diversity in the mediterranean sea: longitudinal patterns related to water column structure in late spring�early summer. aquatic microbial ecology 22, 69�78. tintinnid ciliates of the amundsen sea j.r. dolan et al. 10 (page number not for citation purpose) citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 dolan j.r. 2010. morphology and ecology in tintinnid ciliates of the marine plankton: correlates of lorica dimensions. acta protozoologica 49, 235�344. dolan j.r., claustre h. & vidussi f. 1999. planktonic ciliates in the mediterranean sea: longitudinal trends. deep-sea research part i 46, 2025�2039. dolan j.r. & marrase c. 1995. planktonic ciliate distribution relative to a deep chlorophyll maximum: catalan sea, n.w. mediterranean, june 1993. deep-sea research part i 42, 1965�1987. dolan j.r., pierce r.w., yang e.j. & kim s.y. 2012. southern ocean biogeography of tintinnid ciliates of the marine plankton. journal of eukaryotic microbiology 59, 511�519. dolan j.r., ritchie m.r. & ras j. 2007. the neutral community structure of planktonic herbivores, tintinnid ciliates of the microzooplankton, across the se pacific ocean. biogeosciences 4, 297�310. froneman p.w. 2004. protozooplankton community structure and grazing impact in the eastern atlantic sector of the southern ocean in austral summer 1998. deep-sea research part ii 51, 2633�2643. froneman p.w., pakhomov e.a., perissinotto r. & mcquaid c.d. 1996. role of microplankton in the diet and daily ration of antarctic zooplankton species during austral summer. marine ecology progress series 143, 15�23. griffiths h.j. 2010. antarctic marine biodiversity*what do we know about the distribution of life in the southern ocean? plos one 5, e11683, doi: 10.1371/journal.pone.0011683. hada y. 1970. the protozoan plankton of the antarctic and subantarctic seas. japanese scientific research expedition scientific reports 31, 1�51. hopkins t.l. 1987. midwater food web in mcmurdo sound, ross sea, antarctica. marine biology 96, 93�106. karayanni h., christaki u., van wambeke f., denis m. & moutin t. 2005. influence of ciliated protozoa and heterotrophic nanoflagellates on the fate of primary production in the northeast atlantic ocean. journal of geophysical research*oceans 110, c07s15, doi: 10.1029/2004jc002602. kellermann a. 1987. food and feeding ecology of postlarval and juvenile pleurogramma antarcticum (pisces; notothenioidei) in the seasonal pack ice zone off the antarctic peninsula. polar biology 7, 307�315. kim s.y., choi j.k., dolan j.r., shin h.c., lee s.-h. & yang e.j. in press. morphological and ribosomal dna-based characterization of six antarctic tintinnid ciliates from the amundsen sea with phylogenetic analyses. journal of eukaryotic microbiology 60. kofoid c.a. & campbell a.s. 1929. a conspectus of the marine and freshwater ciliata belonging to the suborder tintinnoinea, with descriptions of new species principally from the agassiz expedition to the eastern tropical pacific 1904�1905. university of california publications in zoology 34. berkeley, ca: university of california press. kofoid c.a. & campbell a.s. 1939. reports on the scientific results of the expedition to the eastern tropical pacific, in charge of alexander agassiz, by u.s. fish commission steamer albatross from october, 1904, to march, 1905, lieut. commander l.m. garrett, u.s.n. commanding. xxxvii. the ciliata: the tintinnoinea. bulletin of the museum of comparative zoology, harvard university 84. cambridge, ma: harvard university. kruse s., jansen s., krägefsky s. & bathman u. 2009. gut content analysis of three dominant antarctic copepod species during an induced phytoplankton bloom eifex (european iron fertilization experiment). marine ecology 30, 301�312. laval-peuto m. & brownlee d.c. 1986. identification and systematics of the tintinnina (ciliophora): evaluation and suggestion for improvement. annales de l, institut océanographique paris 62, 69�84. lee s.h., kim b.k., yun m.s., joo h., yang e.j., kim y.n., shin h.c. & lee s. 2012. spatial distribution of phytoplankton productivity in the amundsen sea, antarctica. polar biology 35, 1721�1733. lonsdale d.j., caron d.a., dennett m.r. & schaffner r. 2000. predation by oithona spp. on protozooplankton in the ross sea, antarctica. deep-sea research part ii 47, 3273�3283. mauchline j. 1980. the biology of mysids and euphausiids. advances in marine biology 18. london: academic press. orejas c., gili j.-m. & arntz w. 2003. role of small-plankton communities in the diet of two antarctic octocorals (primnosisis antartica and primnoella sp.) marine ecology progress series 250, 105�116. sassi r. & melo g.d.n. 1986. tintinnina (protozoa* ciliophora*oligotrichida) from the first brazilian expedition to the antarctic. anais da academia brasileira de ciências 58, 63�84. smith j.a., hillenbrand c.d., kuhn g., larter r.d., graham a.g.c., ehrmann w., moreton s.g. & forwick m. 2011. deglacial history of the west antarctic ice sheet in the western amundsen sea embayment. quaternary science reviews 30, 488�505. stoecker d.k. 2012. predators of tintinnids. in j.r. dolan et al. (eds.): the biology and ecology of tintinnid ciliates: models for marine plankton. pp. 122�145. oxford: wiley-blackwell. tagliabue a. & arrigo k.r. 2003. anomalously low zooplankton abundance in the ross sea: an alternative explanation. limnology and oceanography 48, 686�699. tsuda a. & kawaguchi s. 1997. microzooplankton grazing in the surface water of the southern ocean during an austral summer. polar biology 18, 240�245. verity p.g. 2000. grazing experiments and model simulations of the role of zooplankton in phaeocystis food webs. journal of sea research 43, 317�343. wasik a. & mikolaczyk e. 1994. infracilature of cymatocylis affinis/convallaria. acta protozoologica 33, 79�85. wasik a., mikolaczyk e. & ligowski r. 1996. agglutinated loricae of some baltic and antarctic tintinnina species (ciliophora). journal of plankton research 18, 1931�1940. wickham s.a., steinmair u. & kamennaya n. 2011. ciliate distributions and forcing factors in the amundsen and bellingshausen seas (antarctica). aquatic microbial ecology 62, 215�230. j.r. dolan et al. tintinnid ciliates of the amundsen sea citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 williams r., mccall h., pierce r.w. & turner j.t. 1994. speciation of the tintinnid genus cymatocylis by morphometric analysis of the loricae. marine ecology progress series 107, 263�272. yager p.l., sherrell r.m., stammerjohn s.e., alderkamp a.-j., schofield o., abrahamsen e.p., arrigo k.r., bertilsson s., garay d.l., guerrero r., lowry k.e., moksnes p.p., ndungu k., post a.f., randall-goodwin e., riemann l., severmann s., thatje s., van dijken g.l. & wilson s. 2012. aspire: the amundsen sea polynya international research expedition. oceanography 25, 40�53. tintinnid ciliates of the amundsen sea j.r. dolan et al. 12 (page number not for citation purpose) citation: polar research 2013, 32, 19784, http://dx.doi.org/10.3402/polar.v32i0.19784 http://www.polarresearch.net/index.php/polar/article/view/19784 http://dx.doi.org/10.3402/polar.v32i0.19784 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <feff004700650062007200750069006b002000640065007a006500200069006e007300740065006c006c0069006e00670065006e0020006f006d00200064006500200063006f006d007000610074006900620069006c006900740065006900740020006d006500740020005000440046002f0058002d003300200074006500200063006f006e00740072006f006c006500720065006e00200065006e00200061006c006c00650065006e0020005000440046002d0064006f00630075006d0065006e00740065006e002000740065002000700072006f006400750063006500720065006e002000640069006500200063006f006d007000610074006900620065006c0020007a0069006a006e002e0020005000440046002f0058002000690073002000650065006e002000490053004f002d007300740061006e0064006100610072006400200076006f006f00720020006800650074002000750069007400770069007300730065006c0065006e002000760061006e002000670072006100660069007300630068006500200069006e0068006f00750064002e002000520061006100640070006c0065006500670020006400650020006700650062007200750069006b00650072007300680061006e0064006c0065006900640069006e0067002000760061006e0020004100630072006f00620061007400200076006f006f00720020006d00650065007200200069006e0066006f0072006d00610074006900650020006f00760065007200200068006500740020006d0061006b0065006e002000760061006e0020005000440046002d0064006f00630075006d0065006e00740065006e002000640069006500200063006f006d007000610074006900620065006c0020007a0069006a006e0020006d006500740020005000440046002f0058002d0033002e0020004400650020005000440046002d0064006f00630075006d0065006e00740065006e0020006b0075006e006e0065006e00200077006f007200640065006e002000670065006f00700065006e00640020006d006500740020004100630072006f00620061007400200065006e002000520065006100640065007200200034002e003000200065006e00200068006f006700650072002e> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu (settings for the rampage workflow.) >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice bookreviews03.indd 209book reviews 2004: polar research 23(2), 209–213 book reviews review of “marine mammals of svalbard” by k. m. kovacs, i. gjertz & c. lydersen (2004). tromsø: norwegian polar institute. iv + 60 pp. isbn 82-7666-208-0. william f. perrin southwest fisheries science center, noaa fisheries, 8604 la jolla shores drive, la jolla, ca 92037-1508, usa this slim but elegant volume fi lls a clear need. as the frequency of expeditions and tourist travel to spitsbergen and the other islands of svalbard increases, more and more observations of marine mammals are being made, and there has been no single convenient guide to their identifi cation. the book provides common (english, french, german and norwegian) and scientifi c names, species description and information on distribution, abundance, general ecology, reproduction and life history, diet, exploitation and management, and current status for the polar bear, fi ve species of seals, the walrus, and 12 species of whales and dolphins that can be seen in the waters of svalbard. high-quality portraits (painted by pieter folkens) and photographs are included for each species. the at-sea photographs of cetaceans are especially helpful. the authors have done an outstanding job of summarizing the scattered technical literature on these animals in clear terms understandable by all. this is aided by a glossary of 80 terms. the accounts are packed with interesting details of life history, behavior and ecology usually not encountered in a fi eld guide. a few technical quibbles are in order. the conservation picture for some arctic marine mammals may not be quite as rosy as implied by the statement that “most harvesting is performed within sustainable limits”, especially for the white whale and narwhal. for example, recent studies estimate that present abundance of white whales in west greenland is approximately 20 % of that in 1954 and that continuation of recent catch levels will pose a 90 % risk of extirpation in 20 years. similarly, it is estimated that continued hunts of narwhals at present levels may result in extinction in west greenland in the near future; present abundance is only 15 % of that estimated to exist in 1986. while the situation in norwegian waters may be stable, serious over-exploitation of arctic marine mammals in the atlantic is not strictly a thing of the past. the bowhead was not the fi rst great whale to be depleted by whaling, as stated. that dubious honour belongs to the north atlantic right whale (eubalaena glacialis), which was depleted before the 17th century by the early basque land-based whalers, who also may have played a major role in extermination of the atlantic population of the gray whale, another shore-frequenting species. the “resident, transient and offshore” ecotypes described in the killer whale account were named and studied in the north pacifi c; ecotypes in other regions such as the north atlantic may have different characteristics of preferred prey or social structure. the north pacifi c “resident” designation is actually a misnomer, the resident ecotype is not resident in one area year round, as the account suggests, but ranges widely in the winter; puget sound residents have been sighted off california. the authors depart from the current most widely accepted taxonomic usage (rice 1998), 210 book reviews in using phoca hispida rather than pusa hispida for the ringed seal and phoca groenlandica rather than pagophilus groenlandicus for the harp seal, but this can be a matter of personal preference; there is in fact no “offi cial” world list of scientific names. there is very little to criticize and much to laud in the production and editing of the book. i could fi nd only one typographical error (ridgway’s name is spelled wrong in the list of recommended readings). the binding is fi ne, and the photographic illustrations and other graphics are superb. a quick-identifi cation sheet and forms for reporting sightings are provided in a pocket at the back. this guide should provide good and long service in the fi eld and may result in collection and collation of sightings potentially useful to the scientifi c understanding of these fascinating animals. it is highly recommended for accurate information on the marine mammals one is likely to encounter in and around the far-northern arctic territories of norway. review of marine mammals of svalbard, by k. m. kovacs, i. gjertz & c. lydersen olle melander the swedish tourist authority, box 860, se–101 37 stockholm, sweden. every year, tourists converge on svalbard hoping to catch sight of the big marine mammals. but most tourists are not zoologists. for a temporary visitor, it is no easy task to recognize marine mammals. of course polar bears and walruses are easy to distinguish—and they also top the visitor’s wish list—but tourists also want to see seals and especially whales. these animals seldom “pose” the way polar bears and walruses sometimes do. they may give you no more than a brief glimpse and then leave you wondering: what was that? how big is a seal? what does it eat? as of last summer, tourists and tour guides have a new way of fi nding answers to their questions about svalbard’s fauna: kovacs et al. marine mammals of svalbard. but there are already several fi eld guides and a substantial body of scientifi c literature. does this book add anything new? this is an appealing book in terms of design, size, text and content. it is just the right size to take along with you, and just the right thickness to invite reading. the book itself is too big to shove into your pocket, but just inside the back cover you will fi nd an identifi cation sheet with drawings of the animals. at least you can always carry the id sheet with you. passengers on cruise ships will not fi nd the book’s size any problem. it can be kept close at hand in case you want to read up on animals that have been observed. the authors are knowledgeable. the descriptions of the animals are clear and comprehensible. the language is precise and formulated with scientifi c caution. known facts are described with care; if uncertainties remain, this is stated. the book is clearly organized and its structure easy to grasp. information is presented consistently under the same headings for each individual species. this makes it easy to fi nd one’s way around in the book. it contains more photographs and drawings than other, similar books. the photographs are not all of top quality, but here perhaps the publisher is more to blame than the authors. even though the book is entitled marine mammals of svalbard, it contains general information and glimpses of other parts of these animals’ ranges. thus it can be of use even to people who are not visiting svalbard specifi cally. as the book states in several places, information concerning the range, population, etc. of the marine mammals is uncertain. the authors, whose research fi eld is the mammals of svalbard, give modest population estimates. is this an expression of scientifi c conservatism? how uncertain are the estimates? more knowledge is needed, and in the preface, the authors hope readers visiting svalbard will be inspired to report the animals they see by sending in the sighting sheet tucked into a sleeve at the end of the book. though the aim is admirable, the authors bungle the job a bit by not giving clear reasons for the data collection. in addition, the sighting sheet is enormous, providing over 50 lines on which to report observations. what tourist has the stamina —or the luck—to make that many observations? one is reluctant to report a few scattered observations, which is all one usually gets on a short tourist outing. a postcard-sized reporting sheet, with the address pre-printed, and with a brief explanation of what the data will be used for, would inspire much more participation. in addition, many tourists visit svalbard more than once, though a few years may pass between visits. for them, it would be good if more than << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <feff004200720075006b00200064006900730073006500200069006e006e007300740069006c006c0069006e00670065006e0065002000740069006c002000e50020006f00700070007200650074007400650020005000440046002d0064006f006b0075006d0065006e0074006500720020006d006500640020006800f80079006500720065002000620069006c00640065006f00700070006c00f80073006e0069006e006700200066006f00720020006800f800790020007500740073006b00720069006600740073006b00760061006c00690074006500740020006600f800720020007400720079006b006b002e0020005000440046002d0064006f006b0075006d0065006e0074006500720020006b0061006e002000e50070006e006500730020006d006500640020004100630072006f0062006100740020006f0067002000520065006100640065007200200035002e00300020006f0067002000730065006e006500720065002e00200044006900730073006500200069006e006e007300740069006c006c0069006e00670065006e00650020006b0072006500760065007200200073006b00720069006600740069006e006e00620079006700670069006e0067002e> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice no job name b o o k r e v i e w por_140 470..472 review of how peary reached the pole: the personal story of his assistant, by donald b. macmillan, with an introduction by genevieve m. lemoine, susan a. kaplan & anne witty (2008). montreal & kingston: mcgill queen’s university press. 305 pp. isbn 978-0-7735-3450-6. this beautifully produced reprint edition of donald b. macmillan’s 1934 paean to his mentor robert e. peary arrives just in time for the centennial of peary’s claim to have reached the geographic north pole on 6 april 1909. as the writers of the concise introduction point out, it also arrives in the middle of a growing international focus on how climate change is altering both the environment of the arctic and the human responses to this change. it could even be argued that there is more sustained attention being paid to the high north at this moment than at any time since peary’s famous feud with fellow american claimant to the north pole, frederick a. cook. the introduction also provides a mini-biography of macmillan, a man who enjoyed a very long life and had an underappreciated career introducing generations of researchers to the arctic while developing deep friendships with the natives of greenland. born in 1874 to a seafaring family in provincetown, massachusetts, donald macmillan moved to the state of maine as a boy after the death at sea of his father and the early death of his mother. he worked his way through bowdoin college in brunswick, maine, studying geology and participating in numerous sports. running a summer camp on casco bay, maine, brought him into contact with peary, the much-disputed heavyweight champion of american polar exploration. peary invited macmillan on his 1905/06 polar expedition, but a contractual obligation forced macmillan to decline. when peary failed to reach the pole in 1906, he again invited macmillan north, and so at the age of 33, macmillan found himself as a member of peary’s last great attempt to reach the goal of his lifetime. in this volume, peary looks every bit the cheshire walrus in a remarkable photograph taken at battle harbour, labrador, in september 1909, polar exploration’s wildest and most argued-over month. unfortunately, we do not get the precise date of this image: whether, for example, it was taken before or after peary’s publicrelations disaster of a telegram accusing cook of handing the world a gold brick. reams of psychoanalysis could be produced if this man was putting on this face even in the knowledge of cook’s claim and peary’s awkward dismissal of it, to say nothing of peary’s self-knowledge of the truth, or lack of it, of his own claim to the pole. or, if one believes macmillan’s account—and so far as it goes it is highly convincing—peary merely looks as confident as he should have been in the knowledge that no one could seriously believe that frederick cook could have crossed a thousand miles (1600 km) of pack ice with little more than the shirt on his back. the idea was indeed laughable, but peary— the eternal anti-cook—never possessed the ability to get other people to laugh along with him. through his friendship with president theodore roosevelt and the patronage of, among many others, the national geographic society, peary’s crag of a face became a central icon of roosevelt’s muscular new america. frederick cook was too much of an enigma; walter wellman too much of a technological dilettante; and evelyn briggs baldwin too much of a failure. as the correspondence p.j. capelotti, division of social sciences, pennsylvania state university, abington college, abington, pa 19001, usa. e-mail: pjc@psu.edu polar research 28 2009 470–472 © 2009 the author, journal compilation © 2009 blackwell publishing ltd470 mailto:pjc@psu.edu authors of the introduction correctly point out, when peary went to the arctic, with all the force of american corporate and government power behind him, and then returned claiming that the “ ‘stars and stripes [had been] nailed to the pole’ ” (p. 264), “he became an emblem of what the country aspired to be” (p. xxiii). or, as national geographic’s gilbert grosvenor more nakedly put it in 1920, peary possessed a “rugged integrity, and [a] love for everything american” (grosvenor 1920: 322). the details of peary’s final assault on the north pole as witnessed by macmillan are of primary interest to those seeking answers to that great mystery, to be sure, but more interesting are the contexts within which macmillan places peary’s polar exploration: his experience and the techniques gained from those hard-won trials. the arc of that experience, from the early days in northern greenland learning to ski from eivind astrup to the growing expertise of matthew henson in dog-driving and in the cultural anthropology of the north-west greenland inughuit, macmillan persuasively precludes any serious consideration of cook reaching the pole or anywhere near it. macmillan and robert bartlett had both left peary well before he made his final dash for the pole, with bartlett turning back two degrees from the grail. but, having confirmedly reached that high latitude, macmillan finds it inconceivable that peary did not go the distance, for by that point his refined techniques and remaining personnel had left him “stripped for action” (p. 208). the introduction authors write that macmillan began this account during an arctic cruise in 1928, but had laid out much of the theme in his valedictory on peary’s life in the national geographic after peary’s death in 1920. “do not forget the great word experience”, he had written then (macmillan 1920: 308), and it is this theme that he returns to again and again in his 1928 manuscript, some of which is taken word-for-word from the 1920 article. there are some strange alterations, however, in the eight years separating the two accounts. in 1920, macmillan writes that peary left for the final dash at “nearly the 88th parallel”, with “only 120 miles [193 km] to go” (p. 314). in this account, he writes that peary was “within one hundred and thirty-three miles [214 km] of the pole” (p. 208), which macmillan describes as “comparatively few miles to go”. in 1920, macmillan writes that for the final dash peary took with him “48 of the best dogs of [the remaining] 250” (p. 314). in this account, these become “forty of his best dogs of the one hundred and thirty-three remaining”. for those keeping score, that’s an 11% greater distance with 17% fewer dogs. it seems that not only did macmillan’s worship of peary grow with the years, his impressions of the distances that he believed peary’s methods allowed him to cover also changed. moreover, macmillan’s direct criticism of cook centres on the difference between straight-line distances in the arctic and the distances that a human being actually covers when forced to overcome pressure ridges, recalcitrant dogs, equipment breakdowns and so forth. he puts this extra distance at about 25% of the straight-line distance. if one applies macmillan’s own standard to peary’s final dash from 88°n and back, as laid out in this book (133 nautical miles ¥ 2 + 25%), one arrives at 332.50 nautical miles just for peary to get from the point where he leaves bartlett on 31 march or 1 april, depending on which source you believe, to the pole, and back to the point where he left bartlett. the five or six days to travel to the pole, by macmillan’s reckoning, would be 150 nautical miles or more depending on the condition of the ice and the endurance of the men. either way you slice it, that’s 25–30 nautical miles a day over multi-year ice, and then even more on the return, because macmillan claims they did that on the double and even quadruple march. maybe peary, at the age of 53, did it. more likely, as wally herbert reasoned, peary got to perhaps within 80 miles (128 km) of his goal, close enough to ensure through his spyglass that there was no towering new continent in the distance, and then turned around. what macmillan convincingly demonstrates—within the context of peary’s experience—is that he most certainly could have done it. a very different thing, of course, but it could go far in explaining peary’s walrus smile at battle harbour. if he secretly knew that, he, robert peary, with all his vast experience on the ice, could not do it, then he knew absolutely that it simply could not be done—and certainly not by the likes of frederick cook. recent experiments “proving” that peary made it miss the point on numerous counts, not least the age of the experimenters: the leader was only 30, and could barely duplicate half of peary’s claimed distances over the last five-days’ march. find 10 rugged, dog-driving men, like peary, aged 53, drop them at 88°n, and see how many get to the pole and back in 10 days. beyond the peary–cook debate, macmillan’s book covers much other interesting ground. he gave richard byrd his first taste of polar flying in 1925, but the notion here that this expedition “demonstrated the possibility of such a flight [to the north pole]” (p. xxxvii) is a bit too generous. a particularly fascinating chapter for polar archaeologists, anthropologists and historians of science and exploration occurs when macmillan and two companions re-occupy adolphus greely’s base at fort conger in the summer of 1909 to follow up greely’s tidal observations from 1881–83. the base, in “an excellent state of preservation”, held everything that that the starving international polar year group had left behind, from “boxes of stuffed birds, boxes of geological specimens, book review polar research 28 2009 470–472 © 2009 the author, journal compilation © 2009 blackwell publishing ltd 471 sections of petrified trees, fossils, eskimo skulls, and photographic plates [along with] epaulettes, long swallow tails, and a visored cap of the vintage of 1861” (pp. 229– 230). a final nod goes to the 11 colour plates reproduced here. these were hand-tinted to macmillan’s specifications and used in his public lectures. they are a tribute to the researchers who oversaw their restoration and to the university press that allowed them to appear in the work in an age when such publishers more typically find ways to cheapen the publication process while raising prices. references grosvenor g. 1920. peary’s explorations in the far north. national geographic 37(4), 318–322. macmillan d.b. 1920. peary as a leader. national geographic 37(4), 293–317. book review polar research 28 2009 470–472 © 2009 the author, journal compilation © 2009 blackwell publishing ltd472 doi:10.3402/polar.v33.22926 r e s e a r c h / r e v i e w a r t i c l e permafrost dynamics structure species compositions of oribatid mite (acari: oribatida) communities in sub-arctic palsa mires inkeri markkula section of biodiversity and environmental science, department of biology, university of turku, fi-20014 turku, finland keywords biodiversity; community composition; habitat heterogeneity; oribatid mites; palsa mires; permafrost dynamics. correspondence inkeri markkula, section of biodiversity and environmental science, department of biology, university of turku, fi-20014 turku, finland. e-mail: piinma@utu.fi abstract palsa mires are sub-arctic peatland complexes, vulnerable ecosystems with patches of permafrost. permafrost thawing in palsa mires occurs throughout fennoscandia, probably due to local climatic warming. in palsa mires, permafrost thaw alters hydrological conditions, vegetation structure and microhabitat composition with unknown consequences for invertebrate fauna. this study’s objectives were to examine the role of microhabitat heterogeneity and the effects of permafrost dynamics and thaw on oribatid mite communities in palsa mires. oribatid mites were sampled in two palsa mires in finland and norway. three different types of microhabitats were examined: graminoiddominated wet sites, herb-dominated small hummocks and evergreen shrubdominated permafrost-underlain palsa hummocks. the results indicate that permafrost dynamics are an important factor structuring oribatid mite communities in palsa mires. the community composition of oribatid mites differed remarkably among microhabitats. six species were significantly more abundant in permafrost-underlain microhabitats in relation to non-permafrost microhabitats. none of the species identified occurred exclusively in permafrost-underlain microhabitats. findings suggest that permafrost thaw may not have an impact on species diversity but may alter community composition of oribatid mites in palsa mire ecosystems. palsa mires are sub-arctic mire complexes, found in northern parts of fennoscandia, siberia, canada and alaska. a determinative character of palsa mire is permafrost, which occurs in patches within the mire. the optimum areas for palsa mire occurrence in northern europe are areas of low precipitation (b450 mm), where the mean annual air temperature is between �38c and �58c (luoto, fronzek et al. 2004). in finnish lapland, the southern limit of the palsa region coincides with the �18c mean annual air temperature (seppälä 2011). in fennoscandia, palsa mires are found at the limits of the permafrost zone and are therefore very sensitive to climatic fluctuations (king & seppälä 1987; seppälä 1988). palsa mires are good climate change indicators and identified as ‘‘early warning’’ ecosystems (fronzek et al. 2009). throughout their distribution range in northern finland and scandinavia, palsa mires are degrading (matthews et al. 1997; sollid & sørbel 1998; zuidhoff & kolstrup 2000; luoto & seppälä 2003; fronzek et al. 2006; åkerman & johanssen 2008; hofgaard 2009), probably because of regional climatic warming. palsa mires are highly valued in terms of nature conservation (luoto, heikkinen et al. 2004; fronzek et al. 2009), and listed as a priority habitat type by european union (anonymous 2007). permafrost occurs in palsa mires in the form of palsas, which are large peat hummocks with a permanently frozen core, formed by frost upheaval. the formation and degradation of palsas are natural cyclic processes, which maintain microhabitat diversity in palsa mires. the degradation process of permafrost causes palsa hummocks to collapse, forming remnants such as peat ridges, thermokarst pools, depressions and smaller hummocks (seppälä 1986; zuidhoff 2003; zuidhoff & kolstrup 2005). polar research 2014. # 2014 i. markkula. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 22926, http://dx.doi.org/10.3402/polar.v33.22926 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22926 http://dx.doi.org/10.3402/polar.v33.22926 palsa hummocks create a mosaic of microhabitats within the mire because both microenvironment and vegetation on top of palsa hummocks differ from the wet surroundings. the microenvironments provide habitats for a wide range of flora and fauna and serve as important breeding areas for many bird species (luoto, heikkinen et al. 2004). currently, in many sub-arctic peatlands, more palsas are collapsing than are formed. this leads to changes in surface structures, hydrological conditions and vegetation. this is occurring in palsa mires in finnish lapland (luoto & seppälä 2003; luoto, heikkinen et al. 2004; seppälä 2005), northern sweden (zuidhoff & kolstrup 2000; zuidhoff 2003) and norway (sollid & sørbel 1998; hofgaard 2003). malmer et al. (2005) used aerial images together with ground surveys of plant communities and determined that during the last three decades, the drier sites, which are dominated by ombrotrophic hummock vegetation such as mosses and evergreen dwarf shrubs, had declined, and the wet sites, dominated by tall graminoids, expanded in palsa mire ecosystems. a similar trend consisting of a decrease in hummock areas and an increase in wet area was also documented by zuidhoff (2003). recently, fronzek (2013) evaluated that the area where climatic conditions are suitable for palsa occurrence will decrease remarkably during the 21st century. permafrost thaw can lead to homogenization of habitats in palsa mire ecosystems (luoto, heikkinen et al. 2004). habitat heterogeneity is known to maintain diverse communities of invertebrates through an increase in niche differentiation and resource availability (e.g., anderson 1978; berg et al. 1998; hansen 2000; verberk 2006). therefore, thawing of permafrost in palsa mires may not only result in changes in plant species composition and vegetation structure, but in invertebrate species composition and diversity, too. however, the effects of permafrost thaw on invertebrates inhabiting palsa mires are poorly known. in this study, relationships between oribatid mite (acari: oribatida) community composition and permafrost dynamics in two palsa mire ecosystems in northern finland and norway were investigated. oribatid mites are microarthropods living in various types of habitats, including in soil and dumps, the littoral, decaying wood and tree canopies (weigmann 2006). oribatid mites are one of the most diverse and numerous invertebrate groups in peatlands, where they are an important prey for higher insects (behan-pelletier & bisset 1994; murvanidze & kvavadze 2010). oribatid mites are significant in ecosystem functioning, due to their importance in decomposition and nutrient cycling processes (seastedt 1984). in high-latitude ecosystems, the role of microarthropods is particularly important, because larger soil macro-fauna are absent or have low densities and species diversity (swift et al. 1979). several studies show that microhabitat and resource heterogeneity are important factors structuring oribatid mite communities (hansen & coleman 1998; migge et al. 1998; hansen 2000; mumladze et al. 2013) and that oribatida have a high degree of microhabitat preferences and food-niche partitioning (schneider et al. 2004; erdmann et al. 2007; maraun et al. 2011; nielsen et al. 2012). however, there is also growing evidence that no clear relationships between plant and oribatid mite diversity exist (kaneko et al. 2005; st. john et al. 2006; osler et al. 2006; erdmann et al. 2012). in peatlands, moisture is an important factor affecting the spatial distribution of oribatid mites with intermediate moisture conditions being the optimum for most species (tarraswahlberg 1961; behan-pelletier & bisset 1994). to my knowledge, there are no published studies regarding the communities and microhabitat preferences of oribatida in fennoscandian palsa mires. this study’s objectives were to investigate the effects of permafrost dynamics on oribatid mite communities in a microhabitat mosaic. the following questions were addressed. (1) what kind of oribatid mite communities inhabit palsa mires? (2) are there distinct, characteristic oribatid mite communities in different microhabitats within the mire? (3) are there species that are found only in permafrostunderlain microhabitats? (4) how are oribatid mite communities of palsa mires affected by permafrost thaw? materials and methods study areas data were collected from two palsa mires: ferdesmyra mire in east finnmark, norway, and vaisjeäggi palsa mire in utsjoki, finland. ferdesmyra is a ca. 15 km 2 peatland area 30 km west of kirkenes. the mean annual temperature for the area is �18c, and the mean annual rainfall is 470 mm (norwegian meteorological institute; www.eklima.no). permafrost dynamics and thaw in ferdesmyra mire have been surveyed by the norwegian institute for nature research. a decrease in number, size and height of palsa hummocks was documented in 1970�2008 (hofgaard 2009). today, palsa hummocks are found only in two restricted areas of the mire, and all are in decay. sampling in ferdesmyra was conducted in the northern part of the mire (69848?n; 27814?e, 71 m a.s.l), where decaying palsa hummocks still exist. the vaisjeäggi study area was situated in a palsa mire segment*ca. 2 km in length and 1 km in width*at the species compositions of oribatid mite communities i. markkula 2 (page number not for citation purpose) citation: polar research 2014, 33, 22926, http://dx.doi.org/10.3402/polar.v33.22926 http://www.eklima.no http://www.polarresearch.net/index.php/polar/article/view/22926 http://dx.doi.org/10.3402/polar.v33.22926 south-western end of the larger vaisjeäggi peatland area (69844?n; 29816?e, 282 m a.s.l). in this area, the mean annual temperature recorded at the kevo subarctic research station (12 km south-west from the mire and at 75 m a.s.l.) is �1.68c, and the mean annual rainfall is 415 mm (kevo weather station; www.kevo.utu.fi). in the area where study site was located, mature palsa hummocks reach heights of 1�2 m. sampling three microhabitats in both mires were sampled. microhabitats were selected according to field observations of dominant vegetation and presence/absence of permafrost. the presence of permafrost was detected by a vegetation survey and by detection with an iron probe. microhabitats were: (1) permafrost-underlain palsa hummocks dominated by evergreen dwarf shrubs; (2) nonpermafrost hummocks dominated by herbs; (3) adjacent wet microhabitats dominated by graminoids. because palsa hummocks in ferdesmyra mire are degrading, whereas they are in a mature stage in vaisjeäggi, the study areas differed in some of the microhabitat characteristics. in ferdesmyra, sampled palsa hummocks were between 30 cm and 1.5 m and in vaisjeäggi between 1 and 1.5 m in height. in vaisjeäggi, the wet habitats sampled were internal meadows dominated by carex spp. at the ferdesmyra study site, there were no internal meadow types of microhabitat adjacent to palsa hummocks, but thermokarst pools were abundant. these pools were formed by thawing permafrost, and have been overgrown by sphagnum spp. eriophorum spp. was a dominant vascular plant in the pools. at the ferdesmyra study site, study plots were first established in all existing palsa hummocks (n �5). after that, next to each palsa hummock, one non-permafrost hummock plot and one thermokarst pool plot were chosen. one moss/soil sample of 15 cm in diameter and 5�6 cm thick, was taken in each study plot, resulting in five replicates from all three microhabitat types, 15 samples in total. samples were taken on 8 august 2012. in vaisjeäggi, 15 sampling plots, representing the three microhabitats, were established along a transect set at the south-western edge of the mire. first, study plots were established on top of five separate palsa hummocks. after that, five internal meadow sites and five nonpermafrost hummocks were chosen in a random manner, resulting in 15 study plots. two 10 cm diameter and 5�6 cm thick peat samples were taken in each study plot. from the internal meadow microhabitat in vaisjeäggi, only four samples were analysed because one sample was damaged. samples were taken on 6 august 2011 and 9 august 2012. samples were originally collected for two different projects, but later on data sets from the two mires were combined. for this reason, sample sizes were different between the vaisjeäggi and ferdesmyra study areas. samples were transported to turku, finland, where extraction in tullgren-berlese type funnels started within 48 h after sampling. funnels were run for 8 days, until all samples were dry. oribatid mites were sorted from samples under a microscope, and stored in 75% ethanol. adult mites were identified to species or genus level using light microscopy. they were cleaned in lactic acid before identification. identified material was stored in the zoological museum of the university of turku. the nomenclature used in this paper follows weigmann (2006). field measurements the percentage of vegetation coverage around the sampling plots was measured by using vegetation quadrats of 0.5 m 2 in size. moisture content was detected from a soil/peat sample taken from each study plot. samples were dried in 358c and moisture content was calculated as the difference in sample weight before and after drying (fresh weight minus dry weight). the sample ph was measured in the laboratory using dried and sieved soil (one sample per sampling plot) mixed with distilled water solution (100 ml water, 10 ml dried soil) using a precisa 900 ph meter (dietikon, switzerland). soil ph could not be detected for thermokarst pool samples because samples contained solely sphagnum, and water ph measurements were not available. data analysis to compare moisture content and ph between microhabitats, analyses of variance was performed. differences in vegetation coverage, moisture and ph between microhabitats are shown in tables 1 and 2. differences in abundance of species/genera between the microhabitats and study locations (vaisjeäggi and ferdesmyra) were compared using a generalized linear mixed model (glmm) proc glimmix procedure with tukey-kramer post-hoc multiple comparisons for microhabitat pairs. because the sample size was different in the two study areas, a standardized abundance data*number of individuals �0.01/100 cm2*was used in the analysis. a small number (0.01) was added to the original values to omit the zero abundance values. because the data was not normally distributed, and did not fit poisson or negative binomial distribution, a gamma distribution was i. markkula species compositions of oribatid mite communities citation: polar research 2014, 33, 22926, http://dx.doi.org/10.3402/polar.v33.22926 3 (page number not for citation purpose) http://www.kevo.utu.fi http://www.polarresearch.net/index.php/polar/article/view/22926 http://dx.doi.org/10.3402/polar.v33.22926 used in the analyses. species/genera, which occurred in six or more study plots were included in the analyses. in vaisjeäggi, the proc glimmix procedure was also used to test yearly variation in species abundance. in this analysis, original values and negative binomial distribution were used. to illustrate the differences in oribatid mite community composition between microhabitats, non-metric multidimensional scaling (nmds) was performed. bray-curtis similarity index was used. to minimize the effect of different sample sizes in the two study areas, relative abundance (% of total) of each taxon was calculated for each sample and the relative abundances were used in the analyses. nmds analysis and microhabitats characteristics comparisons were done with past version 2.17 software (http://folk.uio.no/ohammer/past/). other analyses were performed with sas version 6.1 software. results the data consisted of 8101 specimen of oribatida, which were identified to species or genus level. altogether, 28 species and 30 genera were identified. these belonged to 20 families. the number or genera was bigger than number of species because some of the oribatida were identified only to genus level. the mean overall abundance of oribatid mites was highest in palsa hummocks, second highest in nonpermafrost hummocks, and lowest in wet microhabitats (table 3). differences in overall abundance were significant between palsa and wet microhabitats (tukeykramer test p �0.003; table 3). there was no difference in oribatida abundance between the years in vaisjeäggi (glmm; p �0.05). one species, scheloribates initialis, was more abundant in 2011 than in 2012 (glmm; p �0.04). six species*carabodes labyrinthicus, tectocepheus velatus, neoribates aurantiacus, ceratozetes thienemanni, eueremaeus silvestris and camisia biurus*were more numerous in palsa microhabitats than in non-permafrost hummocks (tukeykramer test; table 3). conchogneta traegardhi, carabodes subarcticus, carabodes marginatus and euphthiracarus spp. were significantly more abundant in non-permafrost hummocks than in palsas (tukey-kramer test; table 3). palsa hummock and non-permafrost hummock microhabitats were both dominated by t. velatus. carabodes labyrinthicus was the second most abundant species in palsas (fig. 1; table 3). in vaisjeäggi, melanozetes mollicomus was the most abundant species in non-permafrost hummock microhabitats (23.5%), but in ferdesmyra, it was more numerous in palsas than in non-permafrost hummocks. tectocepheus velatus was the most common species in the study areas. in ferdesmyra, the relative abundance of t. velatus was 50% of all specimens identified from palsa and 24% from non-permafrost hummocks (fig. 1). in vaisjeäggi, 29.5% of individuals identified from palsa microhabitats were t. velatus and 24.4% were c. labyrinthicus. wet microhabitats were dominated by limnozetes ciliatus, platynothrus peltifer and oppiella spp. (fig. 1; table 3). conchogneta traegardhi, t. velatus, and c. biurus were significantly more abundant in ferdesmyra than in vaisjeäggi (table 3). melanozetes mollicomus, m. meridianus, chamobates borealis, c. thienemanni and s. initialis were table 1 microhabitat characteristics: mean moisture content per 1 g sample and ph with standard error of the mean, dominant vegetation and mean percentage of coverage of open area covered by sphagnum or cladina and mosses common in hummocks (polytrichum strictum, dicranum spp.). study area habitat moisture content ph dominant plant coverage % sphagnum cladina�moss ferdesmyra palsa hummock (decaying) 0.6490.01 3.4990.09 empetrum hermaphroditum 0 39.3 non-permafrost hummock 0.7090.01 3.7990.11 rubus chamaemorus 0 0.5 thermokarst pool 0.9490.01 � eriophorum spp. 86.6 0 vaisjeäggi palsa hummock (mature) 0.6290.02 3.5690.11 empetrum hermaphroditum 0 37.0 non-permafrost hummock 0.7290.02 3.9590.14 rubus chamaemorus 0 13.7 internal meadow 0.9190.01 4.7190.38 carex spp. 40.3 0 table 2 analyses of variance test results for ph and moisture content comparisons between microhabitats. microhabitat comparisons p ferdesmyra vaisjeäggi overall pa a vs. np b np vs. we c pa vs. we pa vs. np np vs. we pa vs. we location effect ph 0.013 nsd � � ns 0.04 0.002 ns moisture b0.001 0.02 b0.001 b0.001 b0.001 b0.001 0.001 ns a palsa. b non-permafrost hummock. c wet microhabitat. d not significant. species compositions of oribatid mite communities i. markkula 4 (page number not for citation purpose) citation: polar research 2014, 33, 22926, http://dx.doi.org/10.3402/polar.v33.22926 http://folk.uio.no/ohammer/past/ http://www.polarresearch.net/index.php/polar/article/view/22926 http://dx.doi.org/10.3402/polar.v33.22926 more abundant in vaisjeäggi (table 3). for s. initialis, the differences in abundance are simply the effect of sampling year, as it was more abundant in 2011. on the basis of visual interpretation of the nmds configuration, there are distinct oribatida communities in permafrost-underlain microhabitats in palsa mires. this is clear in vaisjeäggi: oribatida assemblages of palsa hummocks are located at the upper left corner of the configuration and samples taken from non-permafrost hummocks at the lower left corner. in the ferdesmyra study area, assemblages of non-permafrost hummocks are closer to palsa hummock microhabitat assemblages than in vaisjeäggi (fig. 2). discussion in palsa mires, climate change is likely to change the microhabitat ratio. karlgård (2008), bosiö et al. (2012) and fronzek (2013) have predicted that the area covered by dry hummock microhabitats, such as palsas, will decrease remarkably during the coming decades in palsa mires. during the 21st century, a shift toward graminoid and carpet moss vegetation dominance is expected (bosiö et al. 2012), and wet areas dominated by graminoids are predicted to increase to cover 80�87% of palsa mire areas by 2050 (karlgård 2008). the area where climatic conditions are suitable for palsa occurrence will shrink table 3 mean abundance of oribatida, 1000 individuals/m2 9se, in three microhabitat types, the results of tukey-kramer test of multiple comparison of microhabitats, and a test of differences in abundances between two sampling areas. mean abundance microhabitat comparison p location species/genera paa npb wec pa vs. np pa vs. we np vs. we effect p all individuals d 27.8592.92 20.0191.91 13.1693.69 ns e 0.003 0.07 ns tectocepheus velatus (michael 1880) 11.7691.92 2.8090.88 0 b0.0001 b0.0001 b0.0001 0.005 carabodes labyrinthicus (michael 1879) 5.7391.29 0.1490.04 0 b0.0001 b0.0001 b0.0001 ns c. marginatus (michael 1884) 0.5290.23 1.5990.43 0 0.02 b0.0001 b0.0001 ns c. subarcticus (trägardh 1902) 0.2990.17 1.8990.41 0 b0.0001 b0.0001 b0.0001 ns oppiella spp. 2.9090.77 2.7890.56 7.092.79 ns ns 0.37 ns suctobelba spp. 1.6690.40 1.0590.32 0.0190.01 ns b0.0001 b0.0001 0.001 melanozetes mollicomus (c.l. koch 1902) 1.0090.41 2.5891.32 0.1190.06 ns 0.02 0.28 0.002 m. meridianus (sellnick 1928) 0.1090.08 0.3290.22 0 ns b0.0001 b0.0001 b0.0001 scheloribates initialis (berlese 1908) 0.7390.23 0.7090.39 0.0190.01 ns b0.0001 0.02 0.02 scheloribates sp. 0.2490.14 0.0890.06 0 � � � � neoribates aurantiacus (oudemans 1914) 0.8390.32 0.0490.03 0 0.001 b0.0001 ns ns adoristes ovatus (c.l. koch 1839) 0.2690.17 0.9490.36 0.0690.01 ns 0.0007 0.0001 ns camisia biurus (c.l. koch 1839) 0.1590.10 0.0990.06 0 0.004 b0.0001 0.0006 b0.0001 c. solhoeyi (colloff 1993) 0 0.0190.01 0 � � � � conchogneta traegardhi (forsslund 1947) 0.1090.05 1.2490.69 0 0.0002 b0.0001 b0.0001 0.04 eueremaeus silvestris (forsslund 1956) 0.2690.12 0.0490.03 0 0.03 b0.0001 b0.0001 ns nanhermannia sellnicki (forsslund 1958) 0.2690.07 0.6390.17 0.2190.18 ns 0.002 b0.0001 0.0003 ceratozetes thienemanni (willmann 1943) 0.3190.13 0.1590.08 0 b0.0001 b0.0001 b0.0001 b0.0001 chamobates borealis (trägardh 1902) 0.2190.11 0.7690.46 0 ns b0.0001 b0.0001 b0.0001 diapterobates humeralis (hermann 1804) 0.0690.02 0.0690.03 0.0490.03 ns 0.02 0.02 ns phthiracarus spp. 0.1590.08 0.3190.10 0.0590.04 ns 0.004 b0.0001 0.0006 euphthiracarus spp. 0.0190.01 0.5590.21 0 b0.0001 0.03 b0.0001 0.0002 heminothrus longisetosus (willmann 1925) 0.0990.04 0.0590.02 0 ns b0.0001 b0.0001 0.04 limnozetes ciliatus (schrank 1803) 0 0 2.2591.59 ns b0.0001 b0.0001 b0.0001 l. rugosus (sellnick 1923) 0 0 0.1090.04 � � � � platynothrus peltifer (c.l. koch 1839) 0 0.0190.01 2.290.83 ns b0.0001 b0.0001 0.01 neonothrus humicola (forsslund 1955) 0.0490.03 0.0190.01 0 � � � � edwardzetes edwardsii (nicolet 1855) 0.0190.01 0.0390.02 0 � � � � zetomimus furcatus (pearce & warburton 1906) 0 0.3190.20 0.3890.37 � � � � eupelops plicatus (c.l. koch 1836) 0.0390.03 0.0390.03 0 � � � � porobelba spinosa (sellnick 1920) 0.1590.10 0 0 � � � � pergalumna nervosa (berlese 1914) 0.0190.01 0 0 � � � � nothrus pratensis (sellnick 1920) 0 0.0190.01 0.6490.50 � � � � mycobates spp. 0.0290.02 0.0190.01 0.0490.04 � � � � damaeus spp. 0 0.0190.01 0.0190.01 � � � � a palsa. b non-permafrost hummock. c wet habitat. d the total abundance of oribatid mites in each microhabitat type. e not significant. i. markkula species compositions of oribatid mite communities citation: polar research 2014, 33, 22926, http://dx.doi.org/10.3402/polar.v33.22926 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22926 http://dx.doi.org/10.3402/polar.v33.22926 remarkably (fronzek 2013). if annual mean temperatures rise by 48c in comparison to the 1961�1990 period, palsa hummocks will disappear entirely (fronzek 2013). numerous studies address the effects of climate change in oribatid mite communities in the arctic and sub-arctic regions, for example, the direct effects of warming and fertilization (coulson et al. 1996; sjursen et al. 2005a; hågvar & klanderut 2009), the impact of altered freeze� thaw cycles (sjursen et al. 2005b; konestabo et al. 2008), and ice thaw in glaciers (hågvar et al. 2009; see also ingimarsdottir et al. 2012). palsa mires are identified as ‘‘early warning’’ ecosystems vulnerable to changes in climate (luoto, heikkinen et al. 2004). therefore the present study can add a deeper understanding of the overall effects of climate change on sub-arctic soil faunal communities. even though interpretation of ordination figures is subjective (quinn & keough 2002), the nmds analysis strengthens the idea that permafrost dynamics affect the structure and species composition of oribatida communities (fig. 2). this was particularly clear in vaisjeäggi. differences in community composition are also demonstrated in fig. 1, which shows the dominance structure of the oribatida communities in different microhabitats. the nmds stress value was relatively high (0.11), but still usable (see clarke 1993). it should be noted that wet microhabitats appear homogeneous because oppiella, which were abundant in wet habitats, were identified only to genus level. the overall abundance of oribatida was highest in palsa microhabitats. the differences were significant only in comparison with wet microhabitats (table 3). therefore, a loss of palsa hummocks may only have minor impacts in overall abundance of oribatid mites in palsa mires. mean abundances were higher than values of oribatida abundance in russian raised bogs (zaitsev 2013), similar to abundances recorded from caucasus lowland bogs (murvanidze & kvavadze 2010) and lower than in oligotrophic bogs in norway (solhøy 1979). fig. 1 dominance structure of oribatida in (a) ferdesmyra mire and (b) in the vaisjeäggi mire. fig. 2 the non-metric multidimensional scaling ordination configuration based on the oribatida data collected in two mires. symbols represent sampling plots. triangles represent sampling plots in palsa hummock microhabitats, squares non-permafrost hummocks and diamonds wet microhabitats. black symbols represent ferdesmyra and white symbols vaisjeäggi. stress: 0.11. species compositions of oribatid mite communities i. markkula 6 (page number not for citation purpose) citation: polar research 2014, 33, 22926, http://dx.doi.org/10.3402/polar.v33.22926 http://www.polarresearch.net/index.php/polar/article/view/22926 http://dx.doi.org/10.3402/polar.v33.22926 none of the species identified in this study occurred exclusively in the palsa hummock microhabitat, which suggests that a loss of permafrost would have a minor effect on oribatid mite species diversity in the studied sites. however, not all oribatida were identified at a species level, and further conclusions should not be made. even though most of the significant test results in habitat effects were caused by differences in species abundances between wet microhabitats and hummock habitats (palsas and non-permafrost hummocks), the results also indicate differences between permafrostunderlain and non-permafrost hummock habitats. nine species showed microhabitat preferences between palsa and non-permafrost hummocks habitats (table 3). sampling location had also an effect in abundance of limnozetes ciliatus, nanhermannia sellnicki, and platynothrus peltifer. this may be caused by the differences in wet microhabitats sampled, as in ferdesmyra wet microhabitat were more pool-like than in vaisjeäggi due to extensive permafrost thaw (table 3). tectocepheus velatus and carabodes labyrinthicus were the most numerous species in palsa hummock microhabitats (table 3; fig. 1). tectocepheus velatus, which was also a dominant species in non-permafrost hummocks, is a cosmopolitan species with wide habitat preferences (weigmann 2006). it is a pioneer species in many habitats, such as glacier forelands and nunataks (solhøy & solhøy 2000; hågvar et al. 2009; ingimarsdottir et al. 2012; flø & hågvar 2013), and the most widespread species in holarctic peatlands (mumladze et al. 2013; see also sidorchuk 2008). carabodes labyrinthicus has holarctic distribution (karppinen & krivolutsky 1982; weigmann 2006) and is found in abundance in alpine heath (solhøy & skartveit 1975), under tree bark (volker 1986), in tree canopies (behan-pelletier & walter 2000), in the forest floor and in decaying wood (siira-pietikäinen et al. 2008). it is abundant in cladina-lichen in mountain ecosystems (materna 2000) and in tundra (sidorchuk 2009). other species, which were significantly more numerous in palsas than in other microhabitats, are forest dwellers (ceratozetes thienemanni, eueremaeus silvestris), forest-meadow dwellers (neoribates aurantiacus) or prefer variety of habitats (camisia biurus). species, which were significantly more abundant in non-permafrost hummocks, are found both in forests and peatlands (carabodes subarcticus, c. margninatus), or mainly in forests (conchogneta traegardhi; weigmann 2006; huhta et al. 2012). carabodes labyrinthicus, n. aurantiacus and e. silvestris were more numerous in palsa hummocks despite the sampling location (table 3). in palsa mires, these species may have permafrostindicator potential, and are also most likely to be affected by a loss of permafrost-underlain microhabitats. the main differences in community composition between permafrost-underlain and non-permafrost hummocks were caused by a high number of c. labyrinthicus in palsas. this finding is of interest because in high-latitude ecosystems, which are relatively simple from a biodiversity perspective, species loss or gain can have strong impacts on ecosystem functions (chapin & körner 1995). even though the presence of permafrost hummocks in palsa mires may not be an important factor maintaining oribatid mite diversity, their loss can have important, yet unknown, consequences in ecosystem functioning. single species can have an irreplaceable role in soil systems (laakso & setälä 1999a, b). siepel & maaskamp (1994) reported that presence of c. labyrinthicus had negative effect on decomposition rates and co2 production in microcosm experiments. this finding is linked to species traits. c. labyrinthicus is a herbofungivore, which cannot digest chitin of fungal cell-walls. feeding solely on fungal cell contents had negative impact on fungal activity, which resulted in lower decomposition rates (siepel & maaskamp 1994). however, microcosm experiments lack multiple species interactions. also, spatial and temporal effects, which may have a minor role in microcosm, are very important in nature (siepel & maaskamp 1994). the role of individual species in ecosystem functions is often ecosystem-specific (bardgett & wardle 2010). whether individual oribatid mite species have effect on the ecosystem functions such as decomposition and co2 production in palsa mires, remains to be studied. oribatid mites are known to show a high degree of microhabitat preferences and trophic niche partitioning (schneider et al. 2004; erdmann et al. 2007; maraun et al. 2011; nielsen et al. 2012). schneider et al. (2004) reported that species in the genus carabodes had distinct stable isotope signals of nitrogen, indicating the species to occupy different trophic niches. the finding that morphologically similar species can have very different diets, highlights the importance of species-level identifications in oribatida studies. recently mumladze et al. (2013) concluded that the composition of the peat bog oribatid community at a local scale is a function of interspecific interactions, in particular food-niche differentiation. permafrost thaw is likely to alter these interactions because environmental changes can cause shifts in functional space occupation in a community (see mouillot et al. 2013). after environmental change, species with traits that are poorly adapted to the new environment may disappear, and colonization by better-adapted species is likely to occur (mouillot et al. 2013). in palsa mires, permafrost thaw and decrease of permafrostunderlain microhabitats may lead to dominance of i. markkula species compositions of oribatid mite communities citation: polar research 2014, 33, 22926, http://dx.doi.org/10.3402/polar.v33.22926 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22926 http://dx.doi.org/10.3402/polar.v33.22926 generalist, peatland-specialist and hydrophilous oribatid mite species. finally, several studies have reported a high degree of unknown patterns in spatial variability of oribatid mites (caruso et al. 2012; nielsen et al. 2012; franklin et al. 2013), and that sampling effort has remarkable effect on biodiversity investigations of oribatida (franklin et al. 2013). therefore, a study with finer microhabitat resolution (separation among lichen, ericaceous plants, different moss types etc.) with all oribatida individuals identified to species level would be necessary to determine the small-scale distribution patterns of oribatid mites in palsa mires, and to study the links between oribatid mite community composition and vegetation structure. a comparative study of oribatid mite communities of palsa mires and other sub-arctic mire types, especially aapa mires, would also contribute to our understanding of the effects of permafrost thaw in oribatid mite diversity in northern peatlands. this study revealed that permafrost dynamics are an important factor structuring oribatid mite communities in subarctic palsa mires. acknowledgements i am grateful to tero klemola and jouko katajisto for their help with statistics. steve coulson, and an anonymous referee are acknowledged for their valuable comments. thank you to pekka niemelä, ritva penttinen and minna turunen for commenting on the manuscript. kevo subarctic research station staff is acknowledged for providing facilities for fieldwork, and pekka markkula for assistance in sampling. this study has been funded by oskar öflund foundation, societas pro flora et fauna fennica and vuokon luonnonsuojelusäätiö. permission for sampling in ferdesmyra was provided by the county governor of finnmark. robert m. badeau of aura professional english consulting has provided the language content editing for this manuscript. references åkerman h.j. & johansson m. 2008. thawing permafrost and thicker active layers in sub-arctic sweden. permafrost and periglacial processes 19, 279�292. anderson j.m. 1978. interand intra-habitat relationships between woodland cryptostimgata species diversity and the diversity of soil and litter microhabitats. oecologia 32, 341�348. anonymous 2007. interpretation manual of european union habitats. eur 27. brussels: european commission, dg environment. bardgett r.d. & wardle d.a. 2010. aboveground�belowground linkages. biotic interactions, ecosystem processes, and global change. oxford: oxford university press. behan-pelletier v.m. & bissett b. 1994. oribatida of canadian peatlands. memoirs of entomological society of canada 169, 73�88. behan-pelletier v.m. & walter d.e. 2000. biodiversity of oribatid mites (acari: oribatida) in tree canopies and litter. in d.c. coleman & p.f. hendrix (eds.): invertebrates as webmasters in ecosystems. pp. 187�195. london: cabi publishing. berg m.p., kniese j.p., bedaux j.m. & verhoef h.a. 1998. dynamics and stratification of functional groups of microand mesoarthropods in the organic layer of a scots pine forest. biology and fertility of soils 26, 268�284. bosiö j., johansson m., callaghan t.v., johanse b. & christensen t.r. 2012. future vegetation changes in thawing subarctic mires and implications for greenhouse gas exchange*a regional assessment. climate change 115, 379�398. caruso t., taormina m. & migliorini m. 2012. relative role of deterministic and stochastic determinants of soil animal community: a spatially explicit analysis of oribatid mites. journal of animal ecology 81, 214�221. chapin f.s. iii. & körner c. 1995. arctic and alpine biodiversity: patterns, causes and ecosystem consequences. berlin: springer. clarke k.r. 1993. non-parametric multivariate analyses of changes in community structure. australian journal of ecology 18, 117�143. coulson s.j., hodkinson i.d., wooley c., webb n.r., block w., worland m.r. & strathdee j.s. 1996. effects of experimental temperature elevation on high-arctic soil microarthropod populations. polar biology 16, 147�153. erdmann g., otte v., langel r., scheu s. & maraun m. 2007. the trophic structure of bark-living oribatid mite communities analysed with stable isotopes ( 15 n, 13 c) indicates strong niche differentiation. experimental and applied acarology 41, 1�10. erdmann g., scheu s. & maraun m. 2012. regional factors rather than forest type drive the community structure of soil living oribatid mites (acari, oribatida). experimental and applied acarology 57, 157�169. flø d. & hågvar s. 2013. aeral dispersal of mosses and invertebrates close to receding alpine glacier in southern norway. arctic, antarctic and alpine research 45, 481�490. franklin e., de moraes j., landeiroc v.l., de souzab j.l.p., pequenod p.a.c.l., magnussona w.e. & de moraisa j.w. 2013. geographic position of sample grid and removal of uncommon species affect multivariate analyses of diverse assemblages: the case of oribatid mites (acari: oribatida). ecological indicators 34, 172�180. fronzek s. 2013. climate change and the future distribution of palsa mires: ensemble modelling, probabilities and uncertainties. phd thesis, university of helsinki. fronzek s., johansson m., christensen t.r., carter t.r., friborg t. & luoto m. 2009. climate change impacts on subarctic palsa mires and greenhouse gas feedbacks. helsinki: syke. species compositions of oribatid mite communities i. markkula 8 (page number not for citation purpose) citation: polar research 2014, 33, 22926, http://dx.doi.org/10.3402/polar.v33.22926 http://www.polarresearch.net/index.php/polar/article/view/22926 http://dx.doi.org/10.3402/polar.v33.22926 fronzek s., luoto m. & carter t.r. 2006. potential effect of climate change on the distribution of palsa mires in subarctic fennoscandia. climate research 32, 1�12. hågvar s. & klanderut k. 2009. effects of simulated environmental change on alpine soil arthropods. global change biology 15, 2972�2980. hågvar s., solhøy t. & mong c.e. 2009. primary succession of soil mites (acari) in a norwegian glacier foreland, with emphasis on oribatid species. arctic, antarctic, and alpine research 41, 219�227. hansen r.a. 2000. effects of litter habitat complexity and composition on a diverse litter microarthropod assemblage. ecology 81, 1120�1132. hansen r.a. & coleman d.c. 1998. litter complexity and composition are determinants of the diversity and species composition of oribatid mites (acari: oribatida) in litterbags. applied soil ecology 9, 17�23. hofgaard a. 2003. effects of climate change on the distribution and development of palsa peatlands: background and suggestions for a national monitoring project. nina project report 21. trondheim: norwegian institute for nature research. hofgaard a. 2009. overvåking av palsmyr. forstegangsundersokelse i ferdesmyra, ost-finnmark 2008. (monitoring palsa mires. initial survey of ferdesbyra, east finnmark 2008.) nina rapport 476. trondheim: norwegian institute for nature research. huhta v., penttinen r. & pitkänen e. 2012. cultural factors in the distribution of soil mites in finland. memoranda society of fauna and flora fennica 88, 52�70. ingimarsdottir m., caruso t., ripa j., mangusdottir o.b., migliorini m. & hedlund k. 2012. primary assembly of soil communities: disentangling the effect of dispersal and local environment. oecologia 170, 745�754. kaneko n., yasunori s., toshizumi m. & hasegawad m. 2005. oribatid mite community structure and tree species diversity: a link? pedobiologia 49, 521�528. karlgård j. 2008. degrading palsa mires in northern europe: changing vegetation in an altering climate and its potential impact on greenhouse gases. master’s thesis, lund university. karppinen e. & krivolutsky d.a. 1982. list of oribatid mites (acarina, oribatei) of northern palaearctic region. i. europe. acta entomologica fennica 41, 1�32. king l. & seppälä m. 1987. permafrost thickness and distribution in finnish lapland*results of geoelectrical soundings. polarforschung 57, 127�147. konestabo h., michelsen a. & holmstrup m. 2008. responses of springtail and mite populations to prolonged periods of soil freeze�thaw cycles in a sub-arctic ecosystem. applied soil ecology 36, 136�146. laakso j. & setälä h. 1999a. sensitivity of primary production to changes in the architecture of belowground food webs. oikos 87, 57�64. laakso j. & setälä h. 1999b. populationand ecosystemeffects of predation on microbial-feeding nematodes. oecologia 120, 279�286. luoto m., fronzek s. & zuidhoff f.s. 2004. spatial modelling of palsa mires in relation to climate in northern europe. earth surface processes and landforms 29, 1373�1387. luoto m., heikkinen r.k. & carter t.r. 2004. loss of palsa mires in europe and biological consequences. environmental conservation 31, 30�37. luoto m. & seppälä m. 2003. thermokarst ponds as indicators of the former distribution of palsas in finnish lapland. permafrost and periglacial processes 14, 19�27. malmer n., johansson t., olsrud m. & christensen t. r. 2005. vegetation, climatic changes and net carbon sequestration in a north-scandinavian subarctic mire over 30 years. global change biology 11, 1895�1909. maraun m., erdmann g., fischer b.m., pollierer m.m., norton r.a., schneider k. & scheu s. 2011. stable isotopes revisited: their use and limits for oribatid mite trophic ecology. soil biology and biochemistry 43, 877�882. materna j. 2000. oribatid communities (acari: oribatida) inhabiting saxicolous mosses and lichens in the krkonoše mts. (czech republic). pedobiologia 44, 40�62. matthews j.a., dahl s.-o., berrisfjord m.s. & nesje a. 1997. cyclic development and thermokarst degradation of palsas in the mid-alpine zone at leipullan, dovrefjell, southern norway. permafrost and periglacial processes 8, 107�122. migge s., maraun m., scheu s. & schaefer m. 1998. the oribatid mite community (acarina) of pure and mixed stands of beech (fagus sylvatica) and spruce (picea abies) of different age. applied soil ecology 9, 115�121. mouillot d., graham n.a.j., villeger s., mason n.w.h. & bellwood d.r. 2013. a functional approach reveals community responses to disturbances. trends in ecology and evolution 1621, 167�177. mumladze l., murvanidze m. & behan-pelletier v. 2013. compositional patterns in holarctic peat bog inhabiting oribatid mite (acari: oribatida) communities. pedobiologia 56, 41�48. murvanidze m. & kvavadze e. 2010. the inventory of oribatid mites, the main decomposers in bogs of colchic lowland (caucasus, georgia). in m.w. sabelis & j. bruin (eds.): trends in acarology. proceedings of the 12th international congress. pp. 175�178. berlin: springer. nielsen u.n., osler g.h.r., campbell c.d., burslem d.f.r.p. & van der wal r. 2012. predictors of fine-scale spatial variation in soil mite and microbe community composition differ between biotic groups and habitats. pedobiologia 55, 83�91. osler g.h.r., cole l. & keith a.m. 2006. changes in oribatid mite community structure associated with the succession from heather (calluna vulgaris) moorland to birch (betula pubescens) woodland. pedobiologia 50, 323�330. quinn g.p. & keough m.j. 2002. experimental design and data analysis for biologists. cambridge: cambridge university press. schneider k., migge s., norton r.a., scheu s., langel r., reineking a. & maraun m. 2004. trophic niche differentiation in soil microarthropods (oribatida, acari): evidence from stable isotope ratios ( 15 n/ 14 n). soil biology and biochemistry 36, 1769�1774. i. markkula species compositions of oribatid mite communities citation: polar research 2014, 33, 22926, http://dx.doi.org/10.3402/polar.v33.22926 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22926 http://dx.doi.org/10.3402/polar.v33.22926 seastedt t.r. 1984. the role of microarthropods in decomposition and mineralization processes. annual review of entomology 29, 25�46. seppälä m. 1986. the origin of palsas. geografiska annaler 68, 141�147. seppälä m. 1988. palsas and related forms. in m.j. clark (ed.): advances in periglacial geomorphology. pp. 247�278. chichester: john wiley. seppälä m. 2005. periglacial environment. in m. seppälä (ed.): the physical geography of fennoscandia. pp. 349�364. oxford: oxford university press. seppälä m. 2011. synthesis of studies of palsa formation underlining the importance of local environmental and physical characteristics. quaternary research 75, 366�370. sidorchuk e.a. 2008. oribatid mites (acari, oribatei) of three fens in the northern part of european russia. entomological review 88, 485�490. sidorchuk e.a. 2009. new data on the fauna of oribatid mites (acari, oribatida) from the polar urals. entomological review 89, 554�563. siepel h. & maaskamp f. 1994. mites of different feeding guilds affect decomposition of organic matter. soil biology and biochemistry 26, 1389�1394. siira-pietikäinen a., penttinen r. & huhta v. 2008. oribatid mites (acari: oribatida) in boreal forest floor and decaying wood. pedobiologia 52, 111�118. sjursen h., michelsen a. & holmstrup m. 2005a. effects of long-term soil warming and fertilisation on microarthropod abundances in three sub-arctic ecosystems. applied soil ecology 30, 148�161. sjursen h., michelsen a. & holmstrup m. 2005b. effects of freeze�thaw cycles on microarthropods and nutrient availability in a sub-arctic soil. applied soil ecology 28, 79�93. solhøy t. 1979. oribatids (acari) from an oligotrophic bog in western norway. fauna norvegica serie b 26, 91�94. solhøy t. & skartveit a. 1975. influence of various temperature approximations on estimates of field respiration in a mountain community. in f.e. wielgolaski (ed.): fennoscandian tundra ecosystems. pp. 111�116. berlin: springer. solhøy i.w. & solhøy t. 2000. the fossil oribatid mite fauna (acari: oribatida) in late-glacial and early-holocene sediments in kråkenes lake, western norway. journal of paleolimnology 23, 35�47. sollid j.l. & sørbel l. 1998. palsa bogs as a climate indicator* examples from dovrefjell, southern norway. ambio 27, 287�291. st. john m.g., wall d.h. & behan-pelletier v. 2006. does plant species co-occurrence influence soil mite diversity? ecology 87, 625�633. swift m.j., heal o.w. & anderson j.m. 1979. decomposition in terrestrial ecosystems. oxford: blackwell science. tarras-wahlberg n. 1961. oribatei of a central swedish bog and their environment. oikos 4, 166�171. verberk w. 2006. importance of landscape heterogeneity for the conservation of aquatic macroinvertebrate diversity in bog landscapes. journal of nature conservation 14, 78�90. volker n. 1986. the bark of trees: thermal properties, microclimate and fauna. oecologia 69, 148�160. weigmann g. 2006. hornmilben (oribatida). keltern, germany: goecke and evers. zaitsev a. 2013. oribatid mite communities (acari: oribatida) in different habitats of the polistovsky nature reserve (pskov region, russia). estonian journal of ecology 62, 276�286. zuidhoff f.s. 2003. palsa growth and decay in northern sweden. comprehensive summaries of uppsala dissertations from the faculty of science and technology 813. uppsala: uppsala university. zuidhoff f.s. & kolstrup e. 2000. changes in palsa distribution in relation to climate change in laivadalen, northern sweden, especially 1960�1997. permafrost and periglacial processes 11, 55�69. zuidhoff f.s. & kolstrup e. 2005. palsa development and associated vegetation in northern sweden. arctic, antarctic and alpine research 37, 49�60. species compositions of oribatid mite communities i. markkula 10 (page number not for citation purpose) citation: polar research 2014, 33, 22926, http://dx.doi.org/10.3402/polar.v33.22926 http://www.polarresearch.net/index.php/polar/article/view/22926 http://dx.doi.org/10.3402/polar.v33.22926 untitled << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <feff004f007000740069006f006e00730020007000650072006d0065007400740061006e007400200064002700e900760061006c0075006500720020006c006100200063006f006e0066006f0072006d0069007400e9002000e00020006c00610020006e006f0072006d00650020005000440046002f0058002d003300200065007400200064006500200063006f006e0064006900740069006f006e006e006500720020006c0061002000700072006f00640075006300740069006f006e00200064006500200064006f00630075006d0065006e007400730020005000440046002000e000200063006500740074006500200063006f006e0066006f0072006d0069007400e9002e0020005000440046002f0058002000650073007400200075006e00650020006e006f0072006d0065002000490053004f00200064002700e9006300680061006e0067006500200064006500200063006f006e00740065006e00750020006700720061007000680069007100750065002e00200050006f0075007200200065006e0020007300610076006f0069007200200070006c0075007300200073007500720020006c006100200063007200e9006100740069006f006e00200064006500200064006f00630075006d0065006e00740073002000500044004600200063006f006e0066006f0072006d00650073002000e00020005000440046002f0058002d0033002c00200063006f006e00730075006c00740065007a0020006c00650020004700750069006400650020006400650020006c0027007500740069006c0069007300610074006500750072002000640027004100630072006f006200610074002e00200049006c002000650073007400200070006f0073007300690062006c0065002000640027006f00750076007200690072002000630065007300200064006f00630075006d0065006e007400730020005000440046002000640061006e00730020004100630072006f0062006100740020006500740020005200650061006400650072002c002000760065007200730069006f006e00200034002e00300020006f007500200075006c007400e9007200690065007500720065002e> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice no job name b o o k r e v i e w review of footsteps on the ice: the antarctic diaries of stuart d. paine, second byrd expedition, edited and with an introduction by m. l. paine (2007). columbia, mo: university of missouri press. 368 pp. isbn 978-0-8262-1741-7. if the reader is looking for another rehashing of one of the adventures of the “heroic era” of antarctic exploration, or another reshaping of the same old material about the three or four explorers from that period who get all the attention, m.l. paine’s footsteps on the ice: the antarctic diaries of stuart d. paine, second byrd expedition is not the book for you. but if you are a serious antarctic buff who wants to learn something new, and really get inside one of the early expeditions of the 20th century, paine’s volume will be a compelling read. frankly, few antarctic diaries should be published. while sifting through the archives looking at the musings of some of the fellows who went south before the international geophysical year in 1957–58, a researcher occasionally comes to the point of asking himor herself, “these people were in the midst of a unique and exciting expedition. what didn’t they tell us about it?” no such response will greet this narrative, because paine demonstrates two things one wants in a diarist—a keen eye for detail and a willingness to offend someone else by writing frankly. paine has no axe to grind, but he is honest enough to let you know that not everyone overwinters with the same social grace. paine offers readers insight into an expedition that took place in the 1930s, a period less studied than others, about which comparatively few versions have appeared besides the official one given by the original leader. in paine’s account, we see byrd more accurately, without the filter of the well-oiled publicity machine. paine tells us what byrd’s account omitted: ongoing problems with leadership, alcohol abuse, lazy and unmotivated people, and how—and this happens even in a good expedition— people had days when they wished they had not bothered to come. alcoholism was a serious problem en route south (so byrd could not have been unaware of it), and even more so when the expedition got to the ice. various attempts to find and destroy all alcohol failed to eliminate the problem; indeed, at one point, men opened the compasses and drank the alcohol out of them. leadership problems were made worse when byrd left for his solo overwinter, but existed even when he was present. paine—whose writing leaves the reader to deduce that he was no complainer—faulted the overall lack of organization and purpose of the scientific programme. that everything on the expedition was designed to make byrd look good was not in doubt. paine provides a wonderful insight into the issue of byrd’s decision to overwinter alone, indicating the difficulties it created, its lack of real scientific merit and at times an underlying tone that this effort was more stunt that science. even before the accusation that byrd had faked the north pole flight was proven by raimund e. goerler’s excellent book on the subject, sceptics made the pointed suggestion that, knowing he had faked the north pole flight, byrd had to prove he was brave, or daring, or that he could accomplish something on his own. the brilliance of paine’s diary is that it is so daily: so full of the minutiae that really puts the reader in the hut with correspondence t.h. baughman, department of history and geography, university of central oklahoma, edmond, ok 73034, usa. e-mail: tbaughman@ ucok.edu polar research 27 2008 87–88 © 2008 the author 87 admiral richard e. byrd’s men, as they muddle through a winter with the leader off at a forward base on his own. narratives by expedition leaders tend to gloss over the petty problems of every day life—the way someone chews his food at dinner or leaves his mess all over the common table. by not doing so, paine presents a more realistic idea of life on a 1930s expedition. paine details the deep frustration, the annoyance with the foibles of others and the questioning of leadership that occur on most such endeavours. stuart paine’s diary peels away the decades and our current notion of today’s antarctica—replete with tourist ships and recreated expeditions, wherein the dogs can be airlifted out if necessary—to a time when leaving for antarctica meant being away from one’s family for the better part of two or three years, and sharing what can be a stress-ridden existence with 55 other men. the narrative conveys how a young and impressionable paine was able to capture some of the magic of the antarctic. one senses that, like so many others who went south in their early years, paine never quite shook off the hold it had over him. he left antarctica, but part of the southern polar region never left him. moreover, paine—without being vindictive—conveys the tensions inherent in closequarter living. by openly discussing such problems, paine gives the general reader an impression of what expedition life was like. m.l. paine has done an excellent job with her preparation of the annotations—they are sharp, concise and virtually always on the mark. much difficult paring must have taken place to produce such a fine result. creating a book as a work of love, out of devotion to a father, does not always lead to a fine, serious book, meriting the attention of others. ms paine has accomplished two goals: a worthy scholarly work contributing to the history of antarctica and a fitting memorial for her father. paine’s story is what it is—a daily account, occasionally, but not often, tedious—and ought to reach a wider audience beyond serious scholars or those who are themselves overwintering at an isolated base. some of the 40 000 tourists who will transit the convergence this antarctic summer ought to buy this book and read it. paine’s story is the real antarctic of scientific research in the old days, every bit as important to understand and appreciate as any of the “heroic era” tales. paine takes you back to antarctica, back to a magical place–one that many people in the past have found spiritually moving. readers of this book will remember why many of us are still moved, still drawn to the ice, either literally each season or just in a chance moment here and there, in our minds. reference goerler r.e. 1998. to the pole: the diary and notebook of richard e. byrd. columbus, oh: ohio state university press. book review polar research 27 2008 87–88 © 2008 the author88 no job name seasonal variation and source areas of airborne lead-210 at ny-ålesund in the high arcticpor_185 345..352 jussi paatero,1 murat buyukay,1 kim holmén,2 juha hatakka1 & yrjö viisanen1 1 finnish meteorological institute, po box 503, fi-00101 helsinki, finland 2 norwegian polar institute, fram centre, no-9296 tromsø, norway abstract high-volume aerosol particle samples were collected onto glass-fibre filters at mount zeppelin global atmosphere watch station, ny-ålesund, svalbard, in 2001–05. the filters were assayed for lead-210 (210pb) by measuring the alpha particles of its in-grown daughter nuclide polonium-210 (210po). the observed 210pb activity concentrations at mount zeppelin vary between <4 and 1060 mbq m-3, with an arithmetic mean of 130 mbq m-3 and a median of 74 mbq m-3. the lowest 210pb activity concentrations are found during summer and the highest are found in winter. this variation is caused by seasonal differences in the mixing conditions of the troposphere, the level of precipitation and the speed of atmospheric chemistry induced by solar radiation. the performed source area analysis, which is based on air mass back trajectories, indicated that in summer, 210pb can be used as a tracer for air masses coming into contact with land areas within the past 5 days. in winter this cannot be performed because of the accumulation of 210pb-carrying aerosol particles into the arctic atmosphere during the arctic night. but even in winter a low 210pb activity concentration indicates that the associated air mass has had little if any contact with land areas. keywords high arctic; lead-210; spitsbergen; trajectory analysis; troposphere. correspondence jussi paatero, finnish meteorological institute, po box 503, fi-00101 helsinki, finland. e-mail: jussi.paatero@fmi.fi doi:10.1111/j.1751-8369.2010.00185.x the arctic region is experiencing environmental changes as a result of climate change and pressures by direct human activities, including air pollutants, as presented in the environmental assessment reports by the arctic climate impact assessment (symon et al. 2005) and the arctic monitoring and assessment programme (amap 2002). the ice cover of the arctic ocean has decreased by 7% per decade during the last 30 years. this phenomenon has a huge impact on the albedo, and thus the atmospheric radiation balance in the area. in the continental arctic regions the depth of the permafrost can extend to several hundreds of metres. during the summer season the uppermost 0.3–2.5 m of the soil melts. the depth of this active layer is increasing by almost 1 cm per year owing to the warming climate. the melting of the permafrost will cause dramatic changes to the environment. for example, lakes can dry out, bogs producing peat can turn into ponds, and methane and carbon dioxide fluxes between the soil and the atmosphere can increase. all these phenomena can change the large-scale atmospheric flow patterns affecting the transport of airborne pollutants, including radionuclides, to the arctic. lead-210 (210pb) is formed in the atmosphere from the radioactive noble gas radon-222 (222rn) emanating from the earth’s crust. of the airborne 222rn, 99% originates from land and only 1% originates from the sea (baskaran et al. 1993). in the air, 222rn, being a noble gas, exists as single atoms. its progeny, including lead-210, are, however, heavy metal atoms, and are rapidly attached to ambient aerosol particles. most of the airborne 210pb activity is attached to accumulation-mode aerosol particles with an aerodynamic diameter of a few hundred nanometres (sanak et al. 1981; papastefanou & bondietti 1991; suzuki et al. 1996; suzuki et al. 1999). owing to its long half-life (22 years), 210pb is removed from the atmosphere by the various scavenging processes, especially wet deposition, of aerosol particles carrying it rather than its radioactive decay. the amount of 210pb in the air is not affected by anthropogenic activities (hötzl & winkler 1987). mean aerosol residence times can be calculated from the activity ratio of 210pb and its progeny, polar research 29 2010 345–352 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 345 mailto:paatero@fmi.fi bismuth-210 (210bi) or polonium-210 (210po) (papastefanou & bondietti 1991). the observed residence times vary between 0 days and over 5 weeks. generally there is a tendency towards longer residence times with decreasing temperature (mattsson 1975; samuelsson et al. 1986; baskaran & shaw 2001). the practically exclusive formation mechanism of airborne 210pb facilitates its use as a tracer for air masses with a recent contact to land areas (preiss et al. 1996). the comprehensive test ban treaty organization gathers information about the 210pb as well as beryllium-7 (7be) activity content of the ground-level air around the globe as a side product to nuclear test monitoring. in this project we have measured the activity concentration of 210pb in the air at the mount zeppelin global atmosphere watch (gaw) station. the gaw programme is coordinated by the world meteorological organization. the gaw monitoring programme includes a co-ordinated global network of some 20 observing stations, and it provides data for scientific assessments and for early warnings of changes in the chemical composition and related physical characteristics of the atmosphere. gaw monitors, among other things, greenhouse gases, ozone and ultraviolet radiation, certain reactive gases and aerosol particles. the data obtained in this study during the 5-year period 2001–05 can be used as a tracer to help identify variations in transport behaviour of air masses, and therefore also of air pollutants, in the arctic region. materials and methods the sampling site was at mount zeppelin gaw station, ny-ålesund, (78°58′n, 11°53′e), on the western coast of spitssbergen, the largest island in the svalbard archipelago (paatero & holmen 2004). the station is located 474 m a.s.l. (fig. 1). high-volume aerosol particle samples were collected onto glass-fibre filters (munktell, falun sweden). the sampler is made of stainless steel. the flow rate was ca. 120 m3 h–1, and was measured with a pressure difference gauge over a throat. three samples per week were collected with filter changes on mondays, wednesdays and fridays. one of the 25 filters was left unexposed, and was used as a field blank sample. all the filters, both samples and field blanks, were stored in cardboard boxes at room temperature (ca. 20°c) before measurement. the indoor 222rn diffusing into the filters during storage has not been found to have a discernible effect on the 210pb content of the filters (paatero et al. 2005). the measurement of 210pb content of the aerosol filters is based on the alpha counting of the in-grown daughter nuclide 210po. the exposed filters and the field blanks were assayed for 210pb 6 months after sampling with an automatic alpha/beta analyser. the technical details of the instrument were described in mattsson et al. (1996). the detector arrangement consists of five gas-flow proportional counters. the flow gas is p-10, a mixture of argon (90%) and methane (10%). the effective window area is 625 cm2. the counter immediately above the filter has a thin plastic window and measures alpha particles. the alpha counting efficiency is 41.5%. the other four counters are for beta particle counting and for anticoincidence background suppression. the results were handled as follows. first the alpha count rate of the field blank was subtracted from the sample alpha count rate. in most cases the field blank did not deviate from the instrumental background. next, a fixed value of 0.5 cpm was subtracted from the alpha count rate to take into consideration the 210po already on the filter at the end of sampling. the alpha count rate was converted to 210po activity by dividing it with the counting efficiency. then the 210pb activity at the end of sampling was calculated from the delay time between the sampling fig. 1 location of the sampling site, mount zeppelin global atmosphere watch station, ny-ålesund, svalbard. airborne lead-210 at ny-ålesund, high arctic j. paatero et al. polar research 29 2010 345–352 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd346 and the measurement, and from the in-grown 210po activity. finally, the 210pb activity was divided by the air volume of the sample to obtain an activity concentration. the method can lead to an overestimation of the 210pb activity concentration because of the uncertainty related to the level of 210po already present on the filter at the end of sampling. this overestimation is expected to be, even in the worst case, less than 20%. the 210po/210pb activity ratio is at its seasonal maximum in late winter because of the long residence time of aerosol particles in the air, allowing time for 210po to accumulate. the effect of unsupported 210po in the air is expected to be a rare incident related to atmospheric long-range transport from volcano eruptions or biomass burning events (stohl et al. 2007; paatero et al. 2009). to check the stability of the instrument, reference samples (plutonium-242 [242pu], strontium-90 [90sr] and iron-55 [55fe]) are measured daily. the measurement uncertainty depends on the level of 210pb present on the filter and counting time. usually the 1s standard deviation of the radioassay varies between 5 and 10%, but can be significantly larger if the activity on the filter is very low. results and discussion altogether 666 aerosol filter samples were collected at the mount zeppelin gaw station in 2001–05. the observed 210pb activity concentrations varied between <4 and 1060 mbq m-3. the median, arithmetic mean and geometric mean activity concentrations were 74, 130 and 74 mbq m-3, respectively. the 10, 25, 75 and 90% percentiles were 16, 33, 180 and 330 mbq m-3, respectively. suzuki et al. (1996) reported 210pb activity concentrations ranging from 83 to 1204 mbq m-3, and an average concentration of 325 mbq m-3 at ny-ålesund in february– march 1995. samuelsson et al. (1986) reported an average concentration of 75 mbq m-3 during a swedish ice-breaker expedition in july–september 1980 between 75° and 83°n, and between greenland and franz josef land. mysłek-laurikainen et al. (2006) reported that the 210pb activity concentration in the air at the polish research station at hornsund, some 200 km south of ny-ålesund, varied between 0 and 1200 mbq m-3. the values found at svalbard are very low compared with continental areas, but are clearly higher than in antarctic areas. for example, the average and maximum monthly 210pb activity concentrations in belgrade, former yugoslavia, were 1200 and 3170 mbq m-3, respectively (todorovic et al. 2000). at marambio research station (64°14′s, 56°43′w), close to the antarctic peninsula, the mean annual 210pb activity concentration was only 4.5 mbq m-3 in 2005 (paatero et al. 2007). the contribution of svalbard itself as a source of airborne 210pb is likely to be very small because of the associated time scales. the area of the islands is only 63 000 km2, and 60% of it is covered with glaciers, with a negligible radon exhalation potential. an air mass travelling from east over the islands with a speed of, e.g., 4 m s–1 would spend only about 12 h above ground before arriving at the west coast of svalbard. the radon accumulated into the air would, on average, still have 5 days left before decaying into 210pb. during these 5 days the air mass would have moved 1700 km away from svalbard. the observed 210pb activity concentrations present a clear seasonal variation, with highest concentrations in winter (fig. 2; table 1). this is attributed to the small fig. 2 airborne 210pb (mbq m-3) at mount zeppelin global atmosphere watch station, svalbard, 2001–05. the sampler was broken from may to december 2004. airborne lead-210 at ny-ålesund, high arcticj. paatero et al. polar research 29 2010 345–352 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 347 level of precipitation, reduced air chemistry and stagnant mixing conditions in the troposphere during the arctic night. these factors increase the aerosol residence time, and thus the accumulation of 210pb in the air. the phenomenon is similar to arctic haze, the accumulation of soot and sulphate particles in the arctic atmosphere during winter (e.g., shaw 1983). the maximum concentrations are only moderately lower in the high arctic compared with finland. for example, in northern finland the average january to march activity concentration was about 280 mbq m-3, and in southern finland 300 mbq m-3 in 1995–97 (paatero & hatakka 2002). the minimum 210pb activity concentrations occur in the high arctic in summer, when the continuous solar radiation induces efficient vertical mixing of the troposphere. at the same time, the level of precipitation, which causes wet deposition and atmospheric chemistry induced by solar radiation, are at their seasonal maximum. this is in agreement with observations in finland. for example, in northern finland the average may to july activity concentration was about 140 mbq m-3, and in southern finland 200 mbq m-3 in 1995–97 (paatero & hatakka 2002). however, the concentrations are even lower in the high arctic. in southern germany the seasonal variation is much less profound than in svalbard, even though the monthly mean concentrations in southern germany are much higher: 400–700 mbq m-3 (winkler & rosner 2000). to analyse the 210pb observations at mount zeppelin, a set of three-dimensional 5-day air mass back trajectories were calculated using the trajectory model flextra (stohl & seibert 1998). the wind fields were obtained from the european centre for medium-range weather forecasts. the trajectories were utilized by two different methods. figure 3 depicts the starting points of trajectories coincident with the lowest 5% of the 210pb activity concentrations: <10 mbq m-3. five days earlier, most of the air masses with a low 210pb content were situated over the arctic ocean, the north atlantic ocean or greenland. only a few starting points are over northern europe or the coastal regions of siberia. on the other hand, most of the trajectory starting points coincident with the highest 5% of 210pb activity concentrations, >400 mbq m-3, are located over siberia (fig. 4). a number of starting points are located between the bering strait and the north pole, contrary to preliminary expectations. this kind of analysis does not, of course, take into account curvatures that the air masses make over the oceans or continents. it is therefore not a proof for particular types of air masses, either continental or maritime. but it gives a general picture of source areas of air masses with high or low activity concentrations of 210pb in the air. the uncertainty related to air mass trajectory calculations has been reviewed by stohl (1998). secondly, a statistical evaluation of the 210pb activity concentrations in different air masses was performed. the 120 hourly locations of each trajectory arriving at mount zeppelin were combined with the 210pb activity concentrations observed during the moment of arrival. next, the concentration–location pairs of all the chosen trajectories were averaged over cells of 1° latitude and 1° longitude. the cell in which mount zeppelin is situated thereby obtains a value close to the average concentration. the activity concentrations obtained in the cells should not be interpreted as absolute concentration values, but rather as concentrations relative to the average concentration. the statistical accuracy decreases with increasing distance from the sampling site, as the averaged area contains fewer and fewer concentration–location pairs. a similar method, but with certain statistical enhancements, has been used previously at the finnish meteorological institute to identify the sources of airborne substances, e.g., atmospheric fine particles and sulphur dioxide, 210pb and 7be in finnish lapland (virkkula et al. 1995; virkkula et al. 1997; paatero & hatakka 2000). two subsets of trajectories and 210pb observations were used in the subsequent analyses: summer months (june–september) and winter months (october–april). these periods were chosen on the basis of the seasonal variation of 210pb activity concentration in fig. 2. the trajectory analysis of summertime source areas of airborne 210pb in svalbard is presented in fig. 5. the highest 210pb activity concentrations are found in air masses coming from northern europe and the northwestern coastal region of russia. somewhat elevated concentrations are associated with air masses coming from arctic canada, too. the lowest concentrations are found in air masses coming from greenland, the north table 1 average monthly activity concentration of 210pb in the air (mbq m-3), measured at the mount zeppelin global atmosphere watch station, svalbard, 2001–05. month 210pb (mbq m-3) average standard error of mean jan. 202 18 feb. 169 15 mar. 237 19 apr. 184 18 may 112 9 jun. 37 4 jul. 33 4 aug. 42 7 sep. 44 5 oct. 93 13 nov. 136 16 dec. 229 37 airborne lead-210 at ny-ålesund, high arctic j. paatero et al. polar research 29 2010 345–352 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd348 fig. 3 starting points (open red squares) of the 5-day-long air mass back trajectories coincident with the lowest 5% of the 210pb activity concentrations, <10 mbq m-3, at mount zeppelin global atmosphere watch station (solid black square). fig. 4 starting points (open red squares) of the 5-day-long air mass back trajectories coincident with the highest 5% of the 210pb activity concentrations, >400 mbq m-3, at mount zeppelin global atmosphere watch station (solid black square). airborne lead-210 at ny-ålesund, high arcticj. paatero et al. polar research 29 2010 345–352 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 349 atlantic ocean and the central arctic ocean. this is in agreement with the classical view that airborne 210pb is a tracer for recent contact of air masses with land areas. in winter, the highest 210pb activity concentrations are found in air masses coming from russia, alaska and arctic canada (fig. 6). high concentrations are also associated with air masses coming from the arctic ocean between alaska, north-eastern siberia and the north pole. air masses containing slightly elevated 210pb activity concentrations arrive in svalbard from northern europe and greenland. the lowest concentrations are found in air masses coming from the north atlantic ocean. the accumulation of 210pb-carrying aerosol particles into the arctic atmosphere during winter explains why the arctic ocean apparently is a source area of 210pb. an interesting detail is the area of lower 210pb activity concentrations between norway and iceland, and the region immediately north-west of norway. this phenomenon can be attributed to the gulf stream going northwards along the coast of norway. this warm sea current seems to cause enough convection in the air aloft that airborne 210pb is diluted to a bigger air volume. conclusions in this report we have presented a 5-year observation series of airborne 210pb at mount zeppelin gaw station. to the best of our knowledge this is the longest data set on airborne 210pb in the high arctic. in winter the 210pb activity concentrations found in svalbard are comparable with those found in finland. in summer, however, the concentrations are much lower than in continental areas. the performed source area analysis, which is based on air mass back trajectories, indicated that in summer 210pb can be used as a tracer for air masses having been in contact with land areas within the past 5 days. in winter this cannot be used because of the accumulation of 210pbcarrying aerosol particles in the arctic atmosphere during the arctic night. but even in winter a low 210pb activity concentration indicates that the associated air mass has had little if any contact with land areas. airborne 210pb has been used in verifications of atmospheric general circulation models (feichter et al. 1991). the data produced in this study might find use in verification activities, as there are few data sets on airborne fig. 5 source areas of airborne 210pb (mbq m-3) at mount zeppelin global atmosphere watch station (solid black square), from june to september 2001–05. airborne lead-210 at ny-ålesund, high arctic j. paatero et al. polar research 29 2010 345–352 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd350 210pb available from 79°n. as a contribution to the international polar year 2007–08, the recent filters have now also been measured for 7be. acknowledgements this work was started with the financial support of the enhancing access to research infrastructure action of the european commission’s human potential programme. the authors are also indebted to the station engineers of the mount zeppelin gaw station for taking care of the sampling programme, to kings bay as for logistical support, and to ms m. laaksonen for the laboratory measurements and preliminary data handling. references amap (arctic monitoring and assessment programme) 2002. arctic pollution 2002. oslo: arctic monitoring and assessment programme. baskaran m., coleman c.h. & santschi p.h. 1993. atmospheric depositional fluxes of 7be and 210pb at galveston and college station, texas. journal of geophysical research—atmospheres 98, 20 555–20 571. baskaran m. & shaw g.e. 2001. residence time of arctic haze aerosols using the concentrations and activity ratios of 210po, 210pb and 7be. journal of aerosol science 32, 443–452. feichter j., brost r.a. & heimann m. 1991. three-dimensional modeling of the concentration and deposition of 210pb aerosols. journal of geophysical research—atmospheres 96, 22 447–22 460. hötzl h. & winkler r. 1987. activity concentrations of 226ra, 228ra, 210pb, 40k and 7be and their temporal variations in surface air. journal of environmental radioactivity 5, 445–458. mattsson r. 1975. measurements of 210pb, 210bi and 210po in urban and rural air in finland. contributions no. 81. helsinki: finnish meteorological institute. mattsson r., paatero j. & hatakka j. 1996. automatic alpha/ beta analyser for air filter samples—absolute determination of radon progeny by pseudo-coincidence techniques. radiation protection dosimetry 63, 133–139. mysłek-laurikainen b., matul m., mikołajewski s., trzaskowska h., preibisz z., garanty i., kubicki m., fig. 6 source areas of airborne 210pb (mbq m-3) at mount zeppelin global atmosphere watch station (small solid black square), from december to april 2001–05. airborne lead-210 at ny-ålesund, high arcticj. paatero et al. polar research 29 2010 345–352 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 351 rakowski p., krynicki t. & stefański m. 2006. air aerosol sampling station aza-1000 at polish polar station in hornsund, spitsbergen. nukleonika 51, 137–140. paatero j., buyukay m., aaltonen v., garcia m.j., sanchéz r., hatakka j., virkkula a. & teinilä k. 2007. airborne lead-210 at research stations aboa and marambio, antarctic. in a.s. paschoa et al. (eds.): book of abstracts of the 8th international symposium on the natural radiation environment (nre-viii), búzios, rio de janeiro, 7–12 october 2007. pp. 65. rio de janeiro: natural radiation environment association. paatero j. & hatakka j. 2000. source areas of airborne 7be and 210pb measured in northern finland. health physics 79, 691–696. paatero j. & hatakka j. 2002. observations of long-lived airborne and deposited radioactivity in finland 1995–1997. publications on air quality no. 30. helsinki: finnish meteorological institute. paatero j., hatakka j., ikäheimonen t.k., klemola s., salminen s. & lehto j. 2005. analysis intercomparison of lead-210 in aerosol filters. in: radiological protection in transition. ssi rapport 2005:15. pp. 55. stockholm: swedish radiation protection authority. paatero j. & holmén k. (eds.) 2004. the first ny-ålesund– pallas–sodankylä atmospheric research workshop, pallas, finland 1–3 march 2004. extended abstracts. reports 2004: 7. helsinki: finnish meteorological institute. paatero j., vesterbacka k., makkonen u., kyllönen k., hellén h., hatakka j. & anttila p. 2009. resuspension of radionuclides into the atmosphere due to forest fires. journal of radioanalytical and nuclear chemistry 282, 473–476. papastefanou c. & bondietti e.a. 1991. mean residence times of atmospheric aerosols in the boundary layer as determined from 210bi/210pb activity ratios. journal of aerosol science 22, 927–931. preiss n., mélières m.-a. & pourchet m. 1996. a compilation of data on lead 210 concentration in surface air and fluxes at the air–surface and water–sediment interfaces. journal of geophysical research—atmospheres 101, 28 847–28 862. samuelsson c., hallstadius l., persson b., hedvall r., holm e. & forkman b. 1986. 222rn and 210pb in the arctic summer air. journal of environmental radioactivity 3, 35–54. sanak j., gaudry a. & lambert g. 1981. size distribution of 210pb aerosols over oceans. geophysical research letters 8, 1067–1069. shaw g.e. 1983. evidence for a central eurasian source area of arctic haze in alaska. nature 299, 815–818. stohl a. 1998. computation, accuracy and applications of trajectories—a review and bibliography. atmospheric environment 32, 947–966. stohl a., berg t., burkhart j. f., fjaeraa a.m., forster c., herber a., hov o., lunder c., mcmillan w.w., oltmans s., shiobara m., simpson d., solberg s., stebel k., strom j., torseth k., treffeisen r., virkkunen k. & yttri k.e. 2007. arctic smoke—record high air pollution levels in the european arctic due to agricultural fires in eastern europe in spring 2006. atmospheric chemistry and physics 7, 511–534. stohl a. & seibert p. 1998. accuracy of trajectories as determined from the conservation of meteorological tracers. quarterly journal of the royal meteorological society 124, 1465–1484. suzuki t., maruyama y., nakayama n., yamada k. & ohta k. 1999. measurement of the 210po/210pb activity ratio in size fractionated aerosols from the coast of the japan sea. atmospheric environment 33, 2285–2288. suzuki t., nakayama n., igarashi m., kamiyama k. & watanabe o. 1996. concentrations of 210pb and 210po in the atmosphere of ny-ålesund. svalbard. memoirs of national institute of polar research 51, 233–237. symon c., arris l. & heal b. (eds.) 2005. arctic climate impact assessment. cambridge: cambridge university press. todorovic d., popovic d., djuric g. & radenkovic m. 2000. 210pb in ground-level air in the belgrade city area. atmospheric environment 34, 3245–3248. virkkula a., hillamo r.e., kerminen v.-m. & stohl a. 1997. the influence of kola peninsula, continental european and marine sources on the number concentrations and scattering coefficients of the atmospheric aerosol in finnish lapland. boreal environment research 2, 317–336. virkkula a., mäkinen m., hillamo r. & stohl a. 1995. atmospheric aerosol in the finnish arctic: particle number concentrations, chemical characteristics, and source analysis. water, air, & soil pollution 85, 1997–2002. winkler r. & rosner g. 2000. seasonal and long-term variation of 210pb concentration in air, atmospheric deposition rate and total deposition velocity in south germany. science of the total environment 263, 57–68. airborne lead-210 at ny-ålesund, high arctic j. paatero et al. polar research 29 2010 345–352 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd352 houssais.indd 99houssais & herbaut 2003: polar research 22(1), 99–106 variability of the ice export through fram strait in 1993–98: the winter 1994/95 anomaly marie-noëlle houssais & christophe herbaut the origin of the large positive anomaly of the fram strait sea ice export which occurred in winter 1994/95 is analysed on the basis of a model simulation of the arctic sea ice cover over the period 1993–98. the overall intra-annual and interannual variability in the model is in good agreement with observational estimates and the 1994/95 anomaly is well reproduced with an amplitude amounting to half of the mean winter value. model results suggest that, concomitant to anomalous export velocities, larger than usual ice thickness in the strait contributes to the outstanding amplitude of the anomaly. analysis on the ice thickness evolution in the strait indicates that the thick ice advected in fram strait at the end of the fall of 1994 originates in the anomalous cyclonic wind stress which prevailed during the preceding summer. this anomalous wind stress resulted in persistent convergence of the ice fl ow against the northern coasts of canada and greenland and in the formation of a large thickness anomaly north of greenland. the anomaly then feeds the fram strait ice fl ow during those following winter months when the local wind forcing in the strait favours ice drift from the north-west. our results suggest that short-term wind stress variations resulting in local thickness changes to the north of fram strait can lead to substantial variability of the fram strait ice export. m.-n. houssais & c. herbaut, laboratoire d’océanographie dynamique et de climatologie, umr cnrsorstom-upmc, université pierre et marie curie, 4 place jussieu, 75 252 paris cedex 05, france, marienoelle.houssais@lodyc.jussieu.fr. fram strait is the major exit for sea ice out of the arctic ocean. a volume export on the order of 0.1 sv approximately counterbalances the net ice production within the arctic ocean. anomalies of this ice export are likely to impact on the arctic ocean sea ice distribution, especially on the multi-year ice area (vinje 2001), while downstream from fram strait such anomalies can result in anomalous volume of melted ice, possibly contributing to large surface salinity anomalies (e.g. the great salinity anomaly; dickson et al. 1988). when occurring in the greenland–icelandic–norwegian seas or, ultimately, in the labrador sea, which are important deep convection areas, such salinity anomalies may have large consequences for the thermohaline circulation of the world ocean. observations show large variations in the fram strait ice export on time scales from days to years. area fl ux variations are primarily attributed to ice velocity changes induced by varying atmospheric forcing. using ice velocities derived from satellite passive microwave imagery over an 18-year period, kwok & rothrock (1999) showed that in winter (october–may) 72 % of the variance of the ice area fl ux can be explained by the sea level pressure gradient across the strait. according to vinje et al. (1998), the weakening of this gradient in summer over the period 1990–96 mostly explains the 50 % reduction of the monthly area fl ux in summer, while the almost doubling of the annual area fl ux between 1990/91 and 1994/ 100 variability of the ice export through fram strait 95 should also be attributed to a change of the gradient between these two periods. reliable estimates of the ice volume fl ux through fram strait are sparse due to diffi culties in collecting measurements of the ice thickness. the 1990–96 time series reconstructed by vinje et al. (1998) suggests strong intraand interannual variability of the volume fl ux with a standard deviation of about 30 % of the mean over that period. the standard deviation of the annual mean ice thickness is only 10 % over the same period, implying that interannual variability of the ice fl ux is largely accounted for by fl uctuations of the ice velocity. some models also reveal strong correlations between the local wind forcing and the ice volume fl ux through fram strait (hakkinen 1993; harder et al. 1998). still, ice thickness anomalies should contribute as well to part of the volume export variability at fram strait. as noticed by vinje et al. (1998), month-to-month variations of the prevailing wind stress direction are frequently observed at fram strait, alternatively bringing into the strait thicker ice from north of greenland or thinner ice from the eastern arctic. the shape of the annual cycle of the volume fl ux may then be altered compared to that of the cross-strait velocity. thickness anomalies may also be formed in remote areas of the arctic ocean and advected across long distances, therefore integrating a complex time history of thermodynamic and dynamic interactions. sev eral scenarios in which ice thickness anomalies are formed in the beaufort sea or the siberian marginal seas have been proposed to explain interannual variability of the fram strait ice export (e.g. tremblay & mysak 1998; venegas & mysak 2000). in this study, we focus on the large positive anomaly of the ice volume export observed in winter 1994/95. model simulations suggest that this anomaly has been one of the largest occurring in the strait during the last fi ve decades (hilmer et al. 1998; arfeuille et al. 2000; vinje 2001); according to observations, it has been the most extreme event over the period 1990–96, with an extra ice export of ca. 0.06 sv, representing more than 60 % of the mean (vinje et al. 1998). the event has been associated with a con comitant ice thickness anomaly since ice draft measurements reveal monthly mean thickness values up to 4 m at that time. ice thickness changes may have contributed to the export variability on other large export events (arfeuille et al. 2000) but the 1995 event is the only one for which draft measurements are available. in this study, we use results of a model simulation over the period 1993–98 to try to understand the origin of the winter 1995 anomaly, as well as the mechanisms and time scales involved. model design and experiments the sea ice model used in this study is based on a variable ice thickness distribution following hibler (1980). four ice classes are considered, including open water. the ice growth rate is determined from the vertical heat conduction equation which is discretized according to the zeroand one-layer approximation for the snow and ice, respectively. the ice dynamics are characterized by a cavitative rheology (flato & hibler 1992) in which shear stress is neglected. the ocean model is based on the primitive equation, z co ordinate, rigid lid ocean code developed at the lab oratoire d’océanographie dynamique and climat ologie in paris (delecluse et al. 1993). the therm o dynamic coupling between the ice and the ocean assumes freezing ocean surface temperature in ice-covered areas and implies heat and salt exchanges at the ice–ocean interface. the dyn amic coupling is such that the surface forcing viewed by the ocean is the wind stress forcing mod i fi ed by the internal ice force, while the ocean exerts a tangential friction force at the bottom of the ice. the domain covers the arctic and adjacent seas, with the southern limit lying at about 40° n. in the vertical, the grid includes 30 levels, with level spacing increasing with depth from 10 m in the top 100 m to 500 m in the deepest levels. in the horizontal, the resolution is slightly anisotropic due to the grid geometry with the “pole” lying over china to overcome the north pole singularity. the horizontal resolution is about 80 100 km in the fram strait area and in the central arctic and increases eastward to reach 40 km in the zonal direction in the kara sea. all model boundaries are treated as closed boundaries. on the southern boundary in the north atlantic sector the temperature and salinity fi elds are restored to climatology. the model has been forced by daily atmospheric forcing fi elds from the period 1993–98 extracted from the 40-year ncep reanalysis (kalnay et al. 1996). the forcing fi elds are surface 101houssais & herbaut 2003: polar research 22(1), 99–106 wind stress, air temperature, specifi c humidity, pressure and wind speed together with incoming longwave and shortwave radiation. since the shortwave radiation was revealed to be unrealistically large, it was modifi ed by adding a correction based on the difference between this fi eld and the corresponding fi eld in the european centre for medium-range weather forecasts (ecmwf) reanalysis (era15). because only the year 1993 was available in the ecmwf data set, the correction was calculated for this particular year and applied identically to the fi ve other years of our ncep forcing. the model is initialized from rest with ocean temperature and salinity distributions from the phc global ocean climatology (steele et al. 2001). the sea ice–ocean coupled system is fi rst spun up for 20 years with a repeated mean annual cycle of the forcing based on the 1993–98 climatology. the model is then run in the interannual mode using the 6-year time series of the forcing fi elds. fram strait ice export variability during 1993–98 figure 1a shows the mean annual cycle of the ice volume transport through fram strait as estimated from 9-day averages of the model transport. the section runs parallel to a meridian of the model grid, approximately from 16° w, 78.5° n to 12.5° e, 80° n. there is a strong seasonal cycle in the transport with a minimum monthly mean of 0.03 sv occurring in july and a maximum of 0.23 sv in march. the winter maximum has, in fact, a two-peak structure with a secondary maximum occurring in december as a result of the weakening of the transport in february. over the period 1993–96 overlapping with vinje et al. (1998), the overall structure of the model annual cycle bears a strong resemblance with the data, although the model shows less weakening of the transport in january and a more rapid decrease of the transport in june–july. the amplitude of the annual cycle is also larger in the model due to higher winter values, especially when considering kwok & rothrock’s (1999) estimates. the model 6-year mean transport of 0.12 sv is therefore overestimated when compared with the 0.09 sv (1 sv = 0.317 × 105 km3 yr-1) of vinje et al. (1998) or with the 0.075 sv of kwok & rothrock (1999), both calculated over a slightly different period (1990–96). the model transport estimate falls in the upper limit of previous model estimates obtained in different periods (e.g. harder et al. 1998; hilmer et al. 1998). the transport shows considerable variability at time scales from weeks to years (fig. 2a). year-toyear transport variations, obtained after removing the mean annual cycle, exhibit very similar time evolution and magnitude as compared with the data. over the overlapping 1993–96 years, signifi cant correlations of 0.72 and 0.69 are found between the low-pass fi ltered (1 month running mean) model anomalies and the data estimates by vinje et al. (1998) and kwok & rothrock (1999), respectively. all time series show a positive anomaly of the ice volume fl ux starting roughly in november 1994, culminating in january 1995 and persisting through the following fig. 1. mean annual cycle of the fram strait (a) ice volume transport and (b) mean ice thickness estimated from the model run (1993–98) (solid line) and from vinje et al.’s (1998) observations (1993 to july 1996) (dashed line). also shown in (a) are kwok & rothrock’s (1999) transport estimates (dotted line). (a) (b) 102 variability of the ice export through fram strait spring. the amplitude of the anomaly averages to 0.06 sv over the duration of the anomaly, both in the model and in vinje et al. (1998), but it is much smaller in kwok & rothrock (1999). another positive anomaly occurs in late 1996, but its magnitude is only half of that in 1995, suggesting that the latter is indeed remarkable. over the 1993–96 period, the mean ice stream thickness in the strait is 2.71 m. for the same period, vinje et al.’s (1998) draft measurements give a value of 2.84 m at 5° w, which corresponds to a strait averaged mean ice thickness of 2.54 m. despite the mean thickness of the ice stream is a bit high in our simulation, its annual variations compare well with observations (fig. 1b). the decrease in january is not as marked in the model as in the observations, nor are the ice thicknesses measured in summer as small as the simulated ones. the model year-to-year variations show some similarities with the data from january 1993 until the middle of 1995, with the most noticeable feature being the occurrence of a large thickness anomaly in winter 1994/95 (fig. 2b). the details of the time evolution of the anomalies over that period however differ. in particular, the anomaly starts developing earlier in the data. since the width of the winter ice stream varies little from year to year in the model, it has little impact on the year-to-year variations of the ice volume fl ux. this has been checked by noting that the area fl ux (not shown) correlates extremely well with the variations of the ice export velocity. however, the width of the ice stream appears to be over estimated in the model and most probably explains the too high simulated winter transports. a possible reason might be that the cavitative fl uid rheology, by neglecting shear stress along the greenland coast, allows for overestimated off-shore component of the ice drift under the effect of the pressure gradient force. despite an fig. 2. time series of the fram strait (a) ice volume transport and (b) mean ice thickness estimated from the model run (1993–98) (solid line) and from vinje et al.’s (1998) observations (1993 to july 1996) (dashed line). thick lines represent the raw time series of the model while light lines are anomalies with respect to the mean annual cycle. also shown in (a) are kwok & rothrock’s (1999) transport estimates (dotted line). (c) raw time series of the mean ice velocity in fram strait for the model (thick line) and the iabp gridded velocities (1993–97) (thin line). model anomalies have been low-pass fi ltered with a 1-month running mean. in (b) the scale of the raw time series is to be read on the right axis. (a) (b) (c) 103houssais & herbaut 2003: polar research 22(1), 99–106 expected discrepancy due to this rheology effect, the mean cross-strait velocity compares very well with iabp gridded buoy velocities (obtained from the polar science center, university of washington, http://iabp.apl.washington.edu) throughout the year (fig. 2c). still, the slightly different orientation (to the south-east) of the model section as compared with the data section (to the south) may hide part of the discrepancy. the winter 1995 event is associated with a strong anomaly of the export velocity which, as for the ice thickness anomaly, occurs earlier in the data than in the model. note that the comparison covers only the 1993–97 period and that buoy velocities with the variance of the interpolated error greater than 0.5 have been excluded from the comparison. in view of the above assessment of the model variability, we consider that the outstanding large ice export which occurred in fram strait in winter 1995 was indeed associated with the export of abnormally thick ice. in the next section, we analyse the ice thickness variability in order to determine the origin of the 1995 anomaly. origin of the winter 1995 thickness anomaly at fram strait averaged over the november 1994 to february 1995 period, the positive ice thickness anomaly in fram strait amounts to 71 cm, with a peak value of 130 cm in mid-february (fig. 2b). the time evolution of the anomaly reveals two successive events of very thick ice, the fi rst occurring in november and the second in february. in fram strait, the patterns of the ice thickness variations are essentially governed by the advection fi eld, except for the ice edge region where the thermodynamics also play a major role (not shown). the question is whether thickness anomalies in the strait should exclusively be attributed to changes in drift direction advecting the mean ice thickness fi eld or if they should also be related to thickness anomalies formed upwind from the strait. the evolution of the 1994/95 thickness anomaly can partly be explained by changes in the dominant direction of the mean ice drift immediately north of the strait (fig. 3) which bring ice of different origins into the strait. from the mean ice thickness distribution it can be deduced that, in november, the ice drift favours advection of thick ice coming from northern greenland, while in december–january, advection from the northeast tends to bring thinner ice from the eastern arctic. an inter mediate situation predominates in february 1995, which is characterized by a strong northerly fl ow turning north-easterly to the east of the strait. although such monthly reversals in the drift direction are not exceptional and have been reported in other studies, what makes the 1994/95 winter anomalous with regard to the ice drift are the high velocities associated with the reversal, as revealed by the multi-year velocity time series shown in fig. 2c. to identify the possible contribution of up stream ice thickness anomalies to the ice ex port variability, the distribution of these anomalies at the end of september 1994—that is just before the appearance of the anomaly in fram strait— is shown in fig. 4a. the distribution is characterized by a well-developed positive feature which extends from the beaufort sea along the canadian archipelago down to the northern coast of greenland. the feature is attributed to the strong convergence of the ice fl ux created by a persistent cyclonic circulation in the preceding summer fig. 3. ice velocity in fram strait in (a) november 1994 and (b) january 1995. (a) (b) 104 variability of the ice export through fram strait (fig. 4b). to check that this anomaly was indeed advected into fram strait and contributed to the thickness anomaly detected in the strait in november, a model experiment was performed in which the daily wind stress in summer (july– september) 1994 is replaced over the entire model domain by the wind stress from the mean annual cycle. comparing fig. 5a and c, the ice buildup appears to be greatly reduced to the north of greenland, while the anomaly disappears in the strait from november through december, indicating that the latter likely originates in the anomalous ice thickness fi eld formed in the western arctic during the previous summer. on the other hand, the reappearance of the anom aly in february (fig. 5b), after the slow de crease in december–january, refl ects the change in the drift direction by the end of january. the fact that the anomaly does not disappear entirely in the sensitivity experiment may indic ate that some thick ice is being created to the north of the strait in december and january. indeed, the strong easterly component of the ice vel ocity during these months (fig. 3b) prevents ice from being exported to the greenland sea. thick ice may also be advected from quite different regions of the arctic without being too much affected by changes in the 1994 summer wind stress. the smaller thickness anomaly in the sensitivity experiment at that time (fig. 5d), however, suggests that some effect of the wind stress change of the previous summer persists through the winter. discussion and concluding remarks the above analysis suggests that large anomalies of the sea ice export through fram strait such as the 1994/95 event can be associated not only with large ice export velocities but also with the presence of abnormally thick ice. several events, in which the contribution due to advection of thicker than usual ice dominates over that due to faster than usual export velocity, have also been identifi ed by arfeuille et al. (2000) in a model simulation over 1948–1998. in their study, however, the 1994/95 event was not associated with a concomitant thickness anomaly in the strait. this may be due to their model missing part of the ice thickness variability, perhaps for the same reasons it overestimates the mean annual ice export. in view of the good correlation between our model thickness time series and the observations by vinje et al. (1998), we are somewhat confi dent that thick ice anomalies were indeed present in fram strait in winter 1995. the fact that the northerly wind stress correlates very well with the ice export at that time (see fig. 3 in arfeuille et al. 2000) is not contradictory with this idea but only indicates that the anomalous transport is also associated with a velocity anomaly when the ice fl ow gets fig. 4. arctic (a) ice thickness anomaly (m) at the end of september 1994 and (b) ice velocity in august 1994. in (a) the anomaly is calculated with respect to the mean annual cycle and the contour increment is 0.25 m. solid isolines indicate positive values; dashed isolines indicate negative values. the bold line is the isoline zero. also shown in (a) is the model section which has been used for transport estimates in fram strait. the dark grey shaded area is the model domain. (a) (b) 105houssais & herbaut 2003: polar research 22(1), 99–106 aligned with the north–south strait axis. our analysis of the generation of the thickness anomaly observed in 1994/95 suggests that some thickness anomalies in fram strait may have a short history, being generated in the area north of greenland by intra-annual variations of the surface wind stress and then advected towards fram strait in a few months. this scenario differs somewhat from those proposed in other studies (tremblay & mysak 1998; mysak & venegas 1998; arfeuille et al. 2000) in which fram strait ice thickness or concentration anomalies were found to be generated in remote areas of the arctic (the beaufort and chukchi seas or the east siberian sea). in these scenarios, the thickness anomalies get advected towards fram strait from their source region, clockwise around the beaufort gyre and / or by the transpolar drift. the long time scales involved in these journeys imply that the anomalies must survive a few seasonal cycles before reaching fram strait, which may substantially alter their amplitude. in contrast, our simulation implies shorter advection time scales which minimizes the impact of seasonal thermodynamic processes and preserves most of the anomaly integrity. the build-up of the thickness anomaly is initiated by the anomalous surface wind in summer 1994. the cyclonic wind stress curl anomaly, which fi rst appears north of the chukchi sea in july, then gets stronger in august and moves to the north of canada by the beginning of september. such cyclonic anomalies are common features of the arctic summer but the 1994 summer one appears to be particular in terms of strength and duration which altogether lead to anomalous ice motion fi eld. the enhanced impact of summer (as compared with winter) anomalies of the wind stress on the arctic ice thickness distribution has already been mentioned by zhang & hunke (2001) to explain winter anomalies of the ice growth rate in the canada basin. although the impact in the present study is rather of a dynamical nature, the fact that the ice is more responsive to the atmospheric vorticity in summer certainly plays a role in our proposed scenario. fram strait ice volume export anomalies such as the one which occured in winter 1994/95 are potentially very important for climate variability. melting of the exported ice may impact on the fig. 5. ice thickness change (m) in fram strait, taking the ice thickness distribution at the end of june 1994 as reference, in the reference experiment in (a) november 1994 and (b) february 1995, and in the sensitivity experiment in (c) november 1994 and (d) february 1995. the contour increment is 0.5 m. (a) (b) (c) (d) 106 variability of the ice export through fram strait ocean circulation via perturbations in the freshwater fl ux. this impact depends on the patterns of ice melting and therefore of the ice drift as the ice moves southward towards the nordic and labrador seas. the high southward drift speed in winter 1995 apparently favoured the export of most of the ice passing through fram strait towards denmark strait (e.g. hilmer et al. 1998), limiting the input of freshwater to the greenland sea and inhibiting the odden formation. in contrast, the fram strait ice export anomaly which occurred in 1968 and was assumed to be associated with the export of thicker ice from northern greenland (walsh & chapman 1990) led to the formation of a wide freshwater signal known as the great salinity anomaly. it is possible that other exports of thick ice, not necessarily associated with high drift speed or above normal pressure gradient in the strait, have led to freshwater anomalies in the past. due to lack of observations, we do not know the frequency of these fram strait ice export anomalies which are associated with thickness anomalies, and our simulation is too short to give insight into this aspect. the mechanism described above, which implies anomalous cyclonic atmospheric circulation in summer, may be linked to the particular period of the study which, according to prosh utinsky & johnson (1997), corresponds to a cyclonic circulation regime. venegas & mysak (2000) recently suggested that time scales on the order of 16 20 years characterize fram strait ice thickness anomalies when they are associated with anomalous westerly winds north of canada and green land. other mechanisms, such as ice growth rate fl uctuations in response to thermodynamic atmospheric forcing, may also lead to ice thickness anomalies with long characteristic time scales (l’hévéder & houssais 2001). this lowfrequency variability is likely to impact on the variability of the fram strait ice export. acknowledgements.—this work was supported by a grant from the french programme national d’etude de la dynamique du climat. computational support was provided by the institut du développement et des ressources en informatique scientifi que. references arfeuille, g., mysak, l. a. & tremblay, l.-b. 2000: simulation of the interannual variability of the wind-driven arctic sea-ice cover during 1958–1998. clim. dyn. 16, 107–121. delecluse, p., madec, g., imbard, m. & lévy, c. 1993: opa version 7 ocean general circulation model: reference man ual. rapport interne lodyc 93/05. lodyc, université pier re et marie curie, paris cedex 05, france. dickson, r. r., meincke, j., malmberg, s.-a. & lee, a. j. 1988. the “great salinity anomaly” in the northern northatlantic 1968–1982. prog. oceanogr. 20, 103–151. flato, g. m. & hibler iii., w. d. 1992: modeling pack ice as a cavitating fl uid. j. phys. oceanogr. 22, 626–651. hakkinen, s. 1993. an arctic source for the great salinity anomaly: a simulation of the arctic ice–ocean system for 1955–1975. j. geophys. res. 98(c9), 16 397–16 410. harder, m., lemke, p. & hilmer, m. 1998: simulation of sea ice transport through fram strait: natural variability and sensitivity to forcing. j. geophys. res. 103(c3), 5595–5606. hibler, w. d. iii 1980: modeling a variable thickness sea ice cover. mon. weather rev. 108, 1943–1972. hilmer, m., harder, m. & lemke, p. 1998: sea ice transport: a highly variable link between arctic and north atlantic. geophys. res. lett. 25, 3359–3362. kalnay, e., kanamitsu, m., kistler, r., collins, w., deaven, d., gandin, l., iredell, m., saha, s., white, g., woollen, j., zhu, y., chelliah, m., ebisuzaki, w., higgins, w., janowiak, j., mo, k. c., ropelewski, c., wang, j., leetmaa, a., reynolds, r., jenne, r. & joseph, d. 1996: the ncep/ ncar 40-year reanalysis project. bull. am. meteorol. soc. 76, 437–471. kwok, r. & rothrock, d. a. 1999: variability of fram strait ice fl ux and north atlantic oscillation. j. geophys. res. 104(c3), 5177–5189. l’hévéder, b. & houssais, m.-n. 2001: investigating the variability of the arctic sea ice thickness in response to a stochastic thermodynamic atmospheric forcing. clim. dyn. 17, 107–125. mysak, l. a. & venegas, s. a. 1998: decadal climate oscillations in the arctic: a new feedback loop for the atmosphere–ice–ocean interactions. geophys. res. lett. 25, 3607–3610. proshutinsky, a. y. & johnson, m. a. 1997: two circulation regimes of the wind-driven arctic ocean. j. geophys. res. 102(c6), 12 493–12 514. steele, m., morley, r. & ermold, w. 2001: phc: a global ocean hydrography with a high-quality arctic ocean. j. clim. 14, 2079–2087. tremblay, l.-b. & mysak, l. a. 1998: on the origin and evolution of sea-ice anomalies in the beaufort–chukchi sea. clim. dyn. 14, 451–460. venegas, s. a & mysak, l. a. 2000: is there a dominant timescale of natural climate variability in the arctic? j. clim. 13, 3412–3434. vinje, t. 2001: fram strait ice fl uxes and atmospheric circulation: 1950–2000. j. clim. 14, 3508–3517. vinje, t., nordlund, n. & kvambekk, a. 1998: monitoring ice thickness in fram strait. j. geophys. res. 103(c5), 10 437-10 449. walsh, j. e. & chapman, w. l. 1990: arctic contribution to upper-ocean variability in the north atlantic. j. clim. 3, 1462–1473. zhang, y. & hunke, e. c. 2001: recent arctic change simulated with a coupled ice–ocean model. j. geophys. res. 106(c3), 4369–4390. geochronologic evidence for early cretaceous volcanic activity on barton peninsula, king george island, antarctica hyeoncheol kim, jong ik lee, moon young choe, moonsup cho, xiangshen zheng, haiqing sang & ji qiu ages of six volcanic and plutonic rocks on barton peninsula, king george island, were determined using “ar/39ar and k-ar isotopic systems. the “ar/”ar and k-ar ages of basaltic andesite and diorite range from 48 my to 74 my and systematically decrease toward the upper stratigraphic section. two specimens of basaltic andesite which occur in the lowermost sequence of the peninsula, however, apparently define two distinct plateau ages of 52-53 my and 119-120 my. the latter is interpreted to represent the primary cooling age of basaltic andesite, whereas the former is interpreted as the thermally-reset age caused by the intrusion of tertiary granitic pluton. the isochron ages calculated from the isotope correlation diagram corroborate our interpretation based on the apparent plateau ages. it is therefore likely that volcanism was active during the early cretaceous on barton peninsula. when the k-ar ages of previous studies are taken into account with our result, the ages of basaltic andesite i n the northern part of the barton peninsula are significantly older than those in the southern part. across the north-west south-east trending barton fault bounding the two parts, there are significant differences in geochronologic and geologic aspects. h . kim. isotope research team, koreo ba.tic science institute. y e o e m dorig 52, rtsung-ku. tuejon 305-333, south korea; j . i . lee & m . y . ciioe. polar science lcihornfor?,, korea oceari research & de~~elopitieni institute, str-dorrg 12 70, anxiti 425170, south korea; m . clio, dept. of geological scrmces, seoul nutionnl uiiiwrsitv. seoiil 151-742, south koreu; x . zlienr, h. sang & j . qiu. institute of geology. chinese acndernq of sciences, beijirig 100029. cliiiiu. the south shetland islands. situated along the pacific margin of the antarctic peninsula (fig. i ), represent a magmatic arc of jurassic to quatern ary age. volcanic sequences and plutonic intru sions in these islands built upon a pre-volcanic. sialic basement of pre-jurassic schists and deformed sedimentary rocks. the latter is pri manly composed of late paiaeozoic-early meso zoic turbiditic submarine fan deposits (smellie. liesa et al. 1995). marine sedimentary rocks containing late jurassic-early cretaceous fossil faunas are succeeded by terrestrial volcanic sandstones and conglomerates, then by basalt to dacite b a s interbedded with andesitic and rhyolitic ignimbrites (smellie. pankhurst et al. 1984; arche et al. 1992; willan et al. 1994; smellie, liesa et al. 1995; hathway & lomas 1998). king george island is the largest island in the south shetland islands and mainly consists of volcanic and plutonic rocks of calc-alkaline affinity. petrography and geochemistry of king george island have been well documented by previous workers (barton 1965; birkenmajer kim et al. 2000: polur research 19f21, 251-260 25 1 f i g . i . structural elements of king george and nelson islands (after birkenmajer 1983) 1983: smellie, pankhurst et al. 1984: tokarski 1988; kang & jin 1989; lee et al. 1996). ferguson (192 i ) has classified the stratiform volcanic complexes of king george island into an older and a younger series, based on the observa tion that the andean intrusive suite intrudes the older series but never the younger series. the older series was tentatively correlated with jurassic rocks of graham land. whereas the younger series with cenozoic rocks (tyrrell 1921). the temporal gap i n these volcanic complexes was confirmed by birkenmajer (1980a-d): cardozo cove and martel inlet groups at admiralty bay (fig. ic), pre dating the andean intrusions, are correlated with the older series of ferguson (19211, whereas the king george island supergroup correlates with the younger series. furthermore, based on lithology and stratigraphy, birkenmajer (1983) divided king george island into three tectonic blocks bounded by strike-slip faults (fig. ic). the andean intru sives are restricted to the central block, or the so-called “backbone”, corresponding to the up thrown barton horst to which barton peninsula belongs (birkenmajer, francalanci et al. 1991). birkenmajer (1983) and kang & jin (1989) reported palaeocene k-ar whole rock and rb-sr biotite ages (60-63 my) for mafic plutonic rocks. recent geochronologic data from barton peninsu la, however, suggest eocene volcanic and plutonic activity (park 1989; lee et al. 1996). k-ar whole rock ages of volcanic rocks range from 35.5 to 48.5 my, whereas those of plutonic rocks mostly from 42.1 to 45.2 my (park 1989). k-ar biotite ages of plutonic rocks are in the range of 41.2 41.9my (lee et al. 1996). because of intrinsic problems, such as the ar loss in k-ar isotopic ages, further discussion on the apparent discre pancy is not warranted. in this paper, we present “ar/39ar as well as k ar ages of volcanic and intrusive rocks on barton peninsula, king george island. “ar/”ar ages provided us with new geochronologic constraints not only for cretaceous volcanic activity on king george island but also the temporal relationship of volcanism in the south shetland islands. geological setting and sample description barton peninsula is composed of volcanic and 252 geochronologic evidence for early cretaceous volcanic activity on barton peninsula fig. 2 . geologic map of barton and weaver peninsulas, king george island, antarctica. u 4 r marian cove a dhnite agglomrate i tuffaceous sandstone and s111stom loww basalt fault plutonic rocks together with minor thin-bedded sandstone and siltstone (fig. 2 ) . volcanic rocks in the peninsula mainly consist of basalt, basaltic andesite, agglomerate and lapilli tuff, whereas plutonic rocks include granodiorite and diorite. acidic dykes are common in diorite. fine-grained diorite, corresponding to the lower part of granitic pluton, consists of plagioclase, clinopyroxene, hornblende, biotite and fe-ti oxides with minor quartz. medium-grained granodiorite, representing a main body of the pluton, is composed of plagioclase. quartz, alkali feldspar, hornblende, biotite and fe-ti oxides. the ubiquitous occur rence of miarolitic cavities indicates that this pluton was emplaced at a shallow level i n the upper crust. petrological and geochemical studies by lee et al. (1996) further suggest that the plutonic rocks are vertically zoned. the pluton is bounded to the south-west by the north-west south-east trending barton fault, which apparently penetrates the whole peninsula. stratification of volcanic rocks is well-pre served to the north of the pluton along the sea cliff. bedding planes of the volcanic sequences generally strike north-east or north-west and consistently dip south at 1040’ n e o r nw (kang & jin 1989). the lapilli tuff mainly occurs to the north of the barton fault and locally to the south. the agglomerate occurs as a ca. 10 m thick layer along the southern coast of the peninsula. both agglomerate and lapilli tuff contain a variety of volcanic glasses and breccias, but lithic fragments of crystalline rocks are absent. basaltic andesites overlain by the lapilli tuff are widespread in the peninsula and generally por phyritic in texture. phenocrysts consist primarily of plagioclase together with minor clinopyroxene and orthopyroxene. holocrystalline groundmass of basaltic andesite commonly shows flow textures defined by the preferred orientation of plagioclase microlites. volcanic rocks on barton peninsula are affected by hydrothermal alteration ( s o et al. 1995) and low-temperature thermal metamorphism (kim et al. 1995). kim et al. (1995) defined two meta morphic zones, changing from a calcite-chlorite zone to a amphibole-chlorite zone toward the pluton on the peninsula. mineral assemblages of metavolcanics are represented by epidote + chlor ite f hornblende f actinolite f calcite (+plagio clase, quartz, opaque minerals), suggesting the greenschist to lower-amphibolite facies meta morphism. further details on thermal metamorph ism will be reported elsewhere (kim et al. 2000). we have analysed three basaltic andesites and one diorite for the “ar/”ar age determination and kim et al. 2000: polar research 19(1), 251-260 2 5 3 two basaltic andesites for the k-ar age determina tion. all samples were collected from the northern part of the barton fault. fresh samples were chosen to minimize the effect of argon loss or contamination, but most of these samples con tained small amounts of secondary minerals such as chlorite and white mica. in addition, all of amphibole crystals of diorite are altered comple tely to actinolite. analytical procedure "hrt"'ar method the analysis for "'ar/"ar age determination was carried out at the institute of geology, chinese academy of sciences, following the procedures described by hu, wang et al. (1985). the samples were ground into sizes of 60-80 mesh and packaged in aluminum foil together with the flux monitors. the flux monitors include zbj hornblende (132.8 f 3.1 mya), zbh-25 biotite (132.7 f 2.8 mya) and international standard sam ple, bsp-i hornblende (2060 f 18 mya). both samples and flux monitors were evacuated and sealed hermetically in quartz ampoules. k2s04 and caf2 were added into each package to monitor the interfering reactions "k(n,p)"ar, 11 k(n.a)40ar. "oca(t~,a)~~ar, 4"ca(n,na)36ar and "ca(n,a)"ar. then, two basaltic andesite (bpo5 and bp13) samples and one diorite (bp03) sample were put in the b4 channel of 49-2 reactor for 4320 minutes and irradiated with fast neutron flux (0.56 x n/cm2sec). the total amount of the integrated fast neutron flux is 1.45 x 10l8 dcm'. on the other hand, one basaltic andesite sample (bp04) was placed in the b8 channel of 49-2 reactor for 3174 minutes and irradiated with instantaneous fast neutron flux (4.22 x 10" n/ cm'sec) and the total amount of the integrated fast neutron flux is 8.04 x 10" n/cm2. a 0.5 mm thick cadmium foil was used as a shield to prevent the interference of slow neutrons. during the irradiation, the sample box was cooled by water, 42°c at the outlet. and was rotated 2 to 8 times per minute to eliminate a transverse gradient of neutron flux. after cooling to a safe dosage, the irradiated samples were put i n an ar-extraction system to carry out step heating analysis. a high frequency oven was used to heat the samples at each step for 2 0 minutes. the extracted argon was purified by cuo and sponge titanium and then introduced directly to rag-10 mass spectrometer for argon isotope analysis. apparent ages were corrected for mass discrimination, interference of k and ca to ar isotope, and "ar radioactive decay. the measured correction factors for the interference of k and c a to ar isotope are ("ar/39ar)k = 3.05 x lo-', ("arl'7ar)ca = 2.64 x lop4 and ( " a i / ~ ' a ~ ) ~ ~ = 6.87 x lo-' (hu, wang et al. 1985). a half life of 35.1 days was adopted to correct the radioactive decay of "ar. uncertainty is quoted as one sigma and does not include that of the calculated j-factor. isochrons were regressed following the method of york (1969). k a r method quantitative analysis of argon was performed by isotopic dilution method using a "ar spike at the institute of geology, chinese academy of sciences. samples were fused at 1450 c-15oo'c for 4 0 minutes. cuo and sponge titanium were used as purifiers and 38ar spike was added during the purification process. the purified argon was directly introduced into rag10 mass spectro meter for isotopic analysis. potassium concentra tion was measured by a flame photometer. the decay constants and isotopic abundance ratio of k used in the age calculation are as follows: a = 5.543 x 10-'oy-', i.,{= 4.962 x 1 0 ' o y l , a, = 0.581 x io-'"y-'. 'ok/k = 0.01 167 (atomic %) (steiger & jager 1977). results the k-ar whole-rock ages of two basaltic andesites are listed in table 1. the k-ar age of bp09 is older than that of bp12, which was collected from a stratigraphically upper part near the barton fault (fig. 2). the '"ar/"ar incre mental heating data and ages of basaltic andesite and diorite are listed i n table 2. the results of 40ar/39ar whole-rock ages are shown in fig. 3. isotope correlation ages of basaltic andesite (bp04, bp05 and bp13) range apparently from 53 & 2 my to 1 18 f 4 my, whereas that of diorite (bp03) is 48.8 -+ 1.5 my. specimen bp04 records an internally discordant 40ar/39ar age spectrum that apparently defines two "plateau" ages: 52 ? i my from low-tempera ture fractions (steps 2 to 4 ) and 119 +. 1 my from high-temperature fractions (steps 6 to 9 ) (fig. 3a). 254 geochronologic evidence for early cretaceous volcanic activity on barton peninsula tnhlr i . k-ar whole-rock age\ of basaltic andesite bpo9 0. i761 0.75 o.9xiox 68.1 0.004383 73.9 it 4.4 bpi1 0.2780 1.04 0.83859 79.8 0.002702 -15.9 * 3.8 these plateau data define, respectively. two isochron ages in 36ar/40ar versus 39art"'ar isotope correlation diagram (fig. 3b). four high temperature steps, recording similar apparent ages, yield a plateau isotope correlation age of 118 f 4 my with a 40ar/"6ar intercept value of 290 f 3. these values are indistinguishable from the plateau age and the atmospheric ratio of 295.5, respectively. on the other hand, three or four steps at temperatures of 460y-9oo"c yield an isochron age of 53 f 2 my which is identical to the apparent "plateau" age of 52 f i my within error range. the 40ar/36ar intercept value of 288 rf: 4 is larger than the 4oar/3yar ratio in the present-day atmos phere, indicating the presence of minor excess ar in low-temperature fractions. specimen bp05 yield a '"ar/"'ar apparent age spectrum with characteristics similar to those of bp04, defining two apparent "plateau" ages of 53.1 f 1.5 myand 1 2 0 . 4 f 1.6my(fig.3c).these ages are consistent with the plateau ages of bp0-t. the old plateau age is based on three high temperature steps comprising >70% of the 3"arlc released. furthermore, the c d k ratio of these steps (table 2 ) are consistently high, suggesting the outgassing from actinolite-hornblende phenocrysts. in the isotope correlation diagram (fig. 3d), data points of low-temperature fractions are too concen trated in a small area to define an isochron age, high temperature steps yield a plateau isotope correlation age of 105 k 5.5 my. because the isotope correle tion ages do not assume any "ar/"arratio, they are considered to be more reliable than the apparent plateau ages. hence, the 105 rf: 5.5 my age is geologically significant and is interpreted to be close to the formation age of basaltic andesite bpos. specimens bp13 and bp03 record concordant whole-rock '"ar/'"ar apparent age spectra (figs. 3e, g) and define the isochron ages of 60.6 f 1.4 my and 48.8 f 1.5 my, respectively. which are identical to plateau age within error range (figs. 3f. g). when we consider the stratigraphic relationship of each sample, the k-ar and 40ar/"'ar whole 40 rock ages of basaltic andesite decrease progres sively from the stratigraphically lower part (bp04 and bp05) to the upper part (bp13) (fig. 4). the apparent ages from low-temperature fractions of bp04 and bp05 indicate that they were partly reset by the emplacement of plutonic rocks about 49 mya (bp03). the "ar/"ar ages from high temperature fractions. however, indicate the pre sence of cretaceous volcanic activity on barton peninsula. on the other hand, k-ar and 4"ar/"ar ages of b p i 2 and bp03, respectively, are con sistent with the previously reported ages (fig. 4), suggesting an early tertiary magmatism. discussion and geologic implications birkenmajer ( 1989) suggested considerable differ ences in stratigraphic succession, ages and charac teristics of three tectonic blocks: i.e. fildes block, barton horst and warszawa block. barton horst, upthrown relative to fildes and warszawa blocks and more deeply eroded than the other two blocks, exposes the plutonic rocks intruding into the old volcanic strata. although mesozoic volcanic activities are suggested in the fildes peninsula and admiralty bay of king george island (ferguson 1921: davies 1982: birkenmajer 1983; birkenmajer. narebski et al. 1983a), no mesozoic isotope age of volcanic rocks are reported from barton peninsula. k-ar and rb-sr ages of volcanic rocks i n the barton horst apparently range from paleocene to eocene (birkenmajer, narebski et al. 1983a, b; kawashita & soliani 1988; park 1989). the k-ar ages of volcanic specimens collected from the southern part of the barton fault (park 1989) (fig. 4) range from 35.5 to 48.5 my. these ages are consistent with the k-ar age of basaltic andesite, b p i 2 (45.9 f 3.8 my). as mentioned above. all of the analysed speci mens were slightly to moderately altered and/or experiencsd low-grade metamorphism. nonethe less, the 4"ar/3yar ages obtained in this study are kim et al. 2000: polnrreseorch 1 9 ( 2 ) , 251-260 255 n v i m t u bk 2 . in cr em en ta l he at in g da ta f or '" a r/" a r ag e de te rm in at io n o f ba sa lt ic a nd es it e an d di or it e. t em p. '"a rc : '0 a r* /'9 a rk 3'1 a rc : a pp ar en t ag e s te p (' c ) (j "a r/ "a r) m (z ha r/ 39 a r) k, (7 7a r/ 3" a r) m ('x a r/ 74 a r) m (1 0 l2 m ol ) (+ i u) (% ) (* i c , m y) rn 4 g < 0 2. e, 0 w 6 b po 4 1 (b as al ti c an de si te ) 2 j = 0 .0 13 39 3 w = 0 .3 5 g 3 5 6 7 8 9 46 0 65 0 80 0 90 0 i0 0 0 11 00 i2 00 i3 00 14 50 3 i s 38 0 8. 52 46 4. 48 28 4. 86 91 16 .4 52 0 9. 24 1 3 7. 42 05 11 .2 76 0 16 .8 75 0 0. 10 26 0. 02 05 0. 00 79 0. 00 89 0. 04 35 0. 01 45 0. 00 8 1 0. 02 23 0. 03 96 i . 97 4 1 0. 55 91 0. 91 36 0. 73 87 1. 87 61 2. 27 29 1. 32 34 4. 81 23 1. 03 22 0. 11 54 0. 07 65 0. 06 14 0. 03 82 0. 15 81 0. 04 97 0. 02 6 i 0. 06 59 0. i1 67 0. 18 0. 85 1. 36 3. 33 0. 72 1. 64 3. 68 1. 19 0. 57 1. 37 f 0 .1 0 i . 3 35 .0 f 2. 0 2. 11 f o .0 3 6. 2 50 .0 f 3. 0 2. 19 f 0 .0 2 10 .0 52 .0 f 1. 0 2. 28 f 0 .0 2 25 .2 54 .0 t 2. 0 3. 76 t 0 .0 5 5. 3 89 .0 f 5. 0 12 0. 0 f 3. 0 5. 13 f 0 .0 3 12 .1 5. 1 i f 0 .0 3 27 .0 11 9. 0 i 1. 0 11 8. 0 f 4. 0 5. 05 t 0 .0 4 8. 7 5. 28 f 0 .0 5 4. 2 12 3. 0 f 6. 0 b p0 5 1 (b as al ti c an de si te ) 2 j = 0 .0 1 0 68 3 w = 0 .2 5 g 4 5 6 7 8 52 0 65 0 78 0 90 0 i0 00 11 00 12 50 14 50 64 3. 67 00 2 13 .2 30 0 92 .7 10 0 10 3. 25 00 76 .2 40 0 2 1. 2 1 00 33 . i 80 0 14 8. 75 00 2. 16 32 0. 7 16 5 0. 30 58 0. 34 28 0. 23 09 0. 05 34 0. 09 88 0. 47 22 2. 74 77 1. 76 86 2. 16 33 0. 05 75 13 .2 30 0 13 .3 34 0 13 .8 13 0 5. 7 13 -3 0. 46 94 0. 16 54 0. 08 25 0. 08 94 0. 10 23 0. 10 43 0. 13 02 0. 18 75 0. 1 i 0. 27 0. 63 0. 79 0. 65 2. 49 1. 85 0. 3 1 13 7. 9 f 3 6. 1 7. 44 f 2 .1 0 1. 6 2. 53 f 0 .6 0 3. 8 48 .2 c 1 2. 6 2. 88 f 0 .3 0 8. 9 54 .6 t 5. 4 52 .5 f 5. 3 2. 77 f 0 .3 0 11 .1 6. 41 t 0 .2 4 9. 2 11 9. 5 f 4. 5 6. 56 f 0 .0 7 35 .0 12 2. 1 f 1. 8 6 .2 9 f0 .1 1 26 .1 11 7. 3 t 2. 5 18 7. 8 f 1 2. 2 10 .3 0 f 0 .5 0 4. 4 b p i3 i (b as al ti c an de si te ) 2 j = 0 .0 10 68 3 w = 0 .2 5 g 3 5 6 7 8 45 0 64 0 78 0 90 0 i0 50 12 00 i3 50 i5 00 38 .4 0 1 0 11 .9 18 0 i 1 .4 43 0 9. 01 52 11 .1 32 0 6. 32 86 5. 75 37 45 .7 14 0 0. 11 60 0. 03 33 0. 02 78 0. 01 97 0. 02 74 0. 01 05 0. 00 89 0. 13 43 2. 35 5 i 1. 07 63 1. 53 10 1. 04 47 1. 67 43 0. 56 39 0. 52 80 3. 95 59 0. 07 60 0. 02 47 0. 02 33 0. 0 i8 9 0. 02 55 0. 01 71 0. 02 15 0. 07 71 0. 53 1. 57 1. 93 2. 84 2. 28 9. 20 13 .7 0 0. 75 3. 43 t 0 .1 2 1. 6 1. 89 f 0 .0 4 4. 7 3. 36 f 0 .0 4 5. 9 3. 27 f 0 .0 3 8. 6 3. 19 i : 0. 03 6. 9 3. 36 f 0 .0 2 28 .1 3. 13 f 0 .0 2 31 .8 6. 50 f 0 .1 3 2. 3 83 .4 f 2. 4 36 .2 t 1. 3 63 .7 f 1. 3 6 1 .9 f 1. 1 60 .4 f 0. 9 63 .6 t 0. 8 59 .3 f 0. 7 12 1. 1 f 3. 9 b p0 3 (d io ri te ) j = 0 .0 10 68 w = 0 .2 0 g 46 0 64 0 75 0 85 0 95 0 10 50 12 00 13 50 15 00 14 0. 91 00 86 .6 67 0 38 .4 35 0 5. 02 59 5. 52 35 3. 51 72 4. 28 57 9. 48 72 11 4. 10 30 0. 45 45 0. 28 05 0. 12 41 0. 00 9 1 0. 01 05 0. 00 66 0. 00 59 0. 02 35 0. 33 89 13 .2 1 20 3. 13 29 1. 78 25 3. 06 52 0. 65 37 0. 30 2. 5 0. 39 85 0. 97 65 15 .7 87 0 0. 12 12 0. 08 21 0. 04 42 0. 03 55 0. 01 68 0. 0 15 9 0. 0 14 9 0. 02 0 i 0. 20 51 0. 14 0. 42 0. 63 16 .6 0 9. 22 18 .7 0 25 .6 0 5. 03 0. 17 8. 25 t 0 .4 5 0. 2 3. 91 i : 0. 27 0. 5 2 .0 2 fo .1 2 0. 8 2. 56 f 0 .0 2 21 .6 2. 46 f 0 .0 2 12 .1 2. 57 f 0 .0 2 24 .4 2. 56 f 0 .0 2 33 .5 2. 62 f 0 .0 3 6. 5 9. 79 f 0 .3 6 0 3 15 2. 4 f 73 .8 f 38 .5 f 48 .7 f 46 .8 f 48 .8 f 18 .6 t 49 .8 f 17 9. 5 t 8. 6 5. 2 2. 5 1. 5 i . 4 i . 5 i .5 1. 7 9. 5 .a r* : r ad io ge ni c a r: j: c al cu la te d jfa ct or ; w : sa m pl e w ei gh t: m : m ea su re d va lu e: " a rt i: ca lc ul at ed ' "a r or ig in at ed f ro m p ot as si um 150 100 y r” 0) ul m c m a a a c e : (a) b p o ~ +-1,2=119*1 my + i 2 0.004 i 50 , 1 , , = 5 2 + 1 m y 0 1 1 1 1 1 1 1 1 1 , 0.003 0.002 0.001 0.000 200 x 150 w ci) z m 100 c e a a 50 0 l , , = 53 i 2 mv i 0.0 0.1 0.2 0.3 0.4 0 . 5 3par/ ‘oar 0 10 2 0 30 40 5 0 60 70 80 90 100 fraction of 39ark released 0.003 l 4 0.002 . l a 0 0.001 0.000 0.0 0.1 39arl ‘oar 0.2 100 50 0.004 0.003 l a ; 0.002 4: 0 0.001 0.000 0 10 20 30 40 50 60 7 0 80 90 100 fraction of 39ark released 1 , = 60.6 f 1.4 my 4qarl’’ar=294.7 i 2 . 3 0.0 0.1 0 . 2 0.3 0.4 3garl ‘oar 200 ( s ) bp03 w m m c m cl 4 i 100 e a 50 0 l t f--1 = 48.4 i 0 . 5 my -b l--=== 0 10 20 30 40 50 60 7 0 80 90 100 fraction of 39ar, released 0.003 0.002 0.001 0.000 1 , = 4 8 . 8 * 1 . 5 my ‘oari 1sar=295.i f 2.1 1 , = 4 8 . 8 * 1 . 5 my ‘oari 1sar=295.i f 2.1 0 0 0.1 0.2 0.3 0.4 39ar/ ‘oar fig. 3. ‘”ar/”ar apparent ages and isotope correlation diagrams of hlrsdtic andesite and diorite from barton peninsula, king george island. antarctica. abbreviations: p = apparent plateau age; 1 = isochron age: 1 = low-temperature fraction,; 2 = high-temperature fractions. (a-f) are for basaltic andesite. and (g-h) for dioritr. kim et al. 2000: polar reseurch 19(2), 251-260 257 580 47' w 58" 44' w u ' i 0 c f i g . 4. map showing the 4"ar/3"ar and k-ar ages compiled from this and previous studies of barton peninsula. king george island. filled circles represent the results of this study. filled and open squares deiiote the results of park (1989) and lee et al. (1996), respectively. filled stars refer to the locations of plant fossils reported by chun et al. (1994). abbreviations: tg, = biotite age; tw = whole rock age: t l = isochron age; t , , = low-temperature fraction isochron age: t12 = high temperature fraction isochron age. considered to be reliable because the initial 4"ar/'6ar ratios of analysed specimens are con sistent with that of present atmospheric argon (295.5). furthermore, the apparent plateau ages are compatible with isochron ages, which support this interpretation. the old isochron ages deter mined in this study thus suggest an early cretaceous volcanic activity on barton peninsula, whereas the young ages are compatible with the eocene ages previously determined from the plutonic rocks. thus, the latter are interpreted to be the ages reset by the thermal effect during the emplacement of plutons. plant fossils of late palaeocene to early oligocene ages occur in reddish to black shales intercalated with agglomerates in the southern part of barton peninsula (fig. 4) (del valle et al. 1984; chun et al. 1994). these results are incompatible with the k-ar and "ar/39ar ages determined by this study, as well as with the previous suggestion of a mesozoic age of volcanic rocks on the barton peninsula (davies 1982; birkenmajer, narebski et al. 1983b). on the other hand. tokarski et al. ( 1987) suggested a possible presence of mesozoic volcanic rocks on barton peninsula. furthermore, plant fossils documented from the jurassic strata of hope bay, antarctic peninsula, are also reported from the cardozo cove group of the barton horst (zastawniak 1981; birkenmajer & zastawniak 1986). the cardozo cove group of the admiralty bay (fig. ic) is correlated with the volcanic sequence of barton peninsula (birken majer 1982). thus, we cannot preclude the occurrence of mesozoic volcanic and volcaniclas tic rocks on barton peninsula. based on the similarity of k-ar ages, jwa et al. (1 992) suggested that the displacement ofthe barton horst with respect to the fildes block is negligible. k-ar and 40ar/39ar ages from the eastern part of pluton, however, indicate the presence of early to late cretaceous volcanism on barton peninsula and do not coincide with an age of 40-60 my for the fildes block. the agglomerate, the lowermost volcanic unit of southern barton peninsula, contains eocene flora fossils but is absent in the north western peninsula across the barton fault. on the other hand, lapilli tuff abruptly diminishes in its occurrence to the south of the barton fault. 25 8 geochronologic evidence for early cretaceous volcanic activity on barton peninsula the apparent discrepancies in geologic and geochronologic data across the barton fault can be accounted for by the presence of significant displacement across the fault. this fault is thought to be a transform fault which is related to the opening of the bransfield strait. previously determined k-ar ages from the volcanic rocks of the southern part of barton peninsula (park 1989) are well correlated with eocene volcanism having widely occurred in the fildes and the warszawa blocks of king george island. hu, zheng et al. (1996) reported late cretac eous to late eocene (92-40 mya) ‘“ad3‘ar and k ar ages in the northern fildes block of king george island. these ages successively decrease toward the north-east, and hu. zheng et al. (1996) have attributed this systematic change to the gradual migration of the volcanic centre (pank hurst & smellie 1983: smellie, pankhurst et al. 1983). our result, however, indicates a large temporal gap along a vertical set of volcanic sequences in a narrow area. furthermore. recent geochronologic studies on livingston island indicate an early to late cretaceous (137 73 mya) volcanic activity (smellie, pallhs et al. 1996: zheng. hu et al. 1997; zheng, sang et al. 1998) corroborating our result. i t is thus likely that at least parts of king george and livingston islands are composed of early cretaceous volcanic sequences. conclusions 1 ) “ar/3’ar step-heating whole-rock ages deter mination of basaltic andesite from barton penin sula in king george island suggest two separate magmatic activities: early cretaceous and middle eocene. 2) “oar/3yar and k-ar ages of volcanic rocks i n the northern pluton part are compatible with the stratigraphic relationship among sedimentary and volcaniclastic sequences. in spite of thermal resetting caused by the intrusion of pluton. 4oar/39ar step-heating ages of basaltic andehite preserve the evidence for early cretaceous volcanic activity in the northern barton peninsula. 3) geologic and geochronologic differences across the north-west-south-east trending fault indicate the presence of tectonic discontinuity on barton peninsula. ackiio~vlrdgenieiirs. this work was financially supported by the ministry of maritime afhirs and fisheries, south korea, through kordi (pp98001 04), and by the nature science foundation of china (19672107t, the chinese academy of sciences (kz951-ai-205-02) and the ministry of science and technology, china (98-927-0 1-06-05), references arche. a,, l6pez-martinez. j . & martinez de pison. e. 1992: sedimentology of the miers bluff formation, livingston island, south shetland islands. i n y. yoshida et al. (eds.): recunf p r o g r e s s in antarctic earth scieiice. pp. 357-362. tokyo: tewd scientific publishing. barton. c. m . (ed.) 1965: the geology of the sourh shetland islands: 111. thc striitigruphy of king georye iskind. br. aiirarcr. suiv. sci. rep. 44. birkenmajer. k. 1980a: tertiary volcanic-sedimentary succes sion at admiralty bay. king george island (south shetland island, antarctica). stud. geol. pol. 64, 7-65. birkenmajer, k. 1980b: report o n geological investigations of king george island. south shetland islands (west antarc tica), in 1978-1979. stud. geol. polon. 64, 89-105. birkenmajer, k. 1 9 8 0 ~ : a revised lithostratigraphic standard for the tertiary of king george island. south shetland islands (west antarctica). bull. pol. acod. sci.. e d i sci. 27( in). 49-51, birkenmajrr, k. 1980d: geology of admiralty bay, king george island (south shetland islands) an outline. pol. polar res. /(/). 29-54. birkenmajer. k. 1982: mesozoic stratiform volcmic-sedimen tary succession and andean intrusions at admiralty bay, king george island (south shetland islands. antarctica). slud. g c d . pol. 74(3). 105-154. birkenmajer, k. 1983: late cenozoic phases of block-faulting on king george island, south shetland islands, west antarctica. bull. pol. acad. sci., eurfh sci. 3 0 ( i r j , 21-32. birkenmajer, k. 1989: a guide to tertiary geochronology of king george island. west antarctica. p o l . p o l a r rrs. /o(4), 55.5-579. birkenmajer. k.. francalanci, l. & peccerillo. a. 1991: petrological and geochemical constraints on the genesis of mesozoic-cenozoic magmatism of king george island, south shetland islands. antarctica. anrarcr. sci. 3(3). 793 30s. birkenmajer. k., narebski, w., nicoletti. m . & petrucciani. c. 19x3a: late cretaceous through late oligocene k-ar ages of the king george island supergroup volcanics, south shet land islands (west antarctica). bull. pol. acud. sci.. ecirrli s i . .io(.i’/4/j), 133-143. birkenmdjer k.. narehski, w.. nicoletti, m . & petrucciani, c. 19x3h: k-ar ages of the “jurassic volcanics” and “andean” intrusions of king george island. south shetland islands (west antarctica). bull. pol. acad. sc.i.. e(irtl7 sri. 3 o ( m j . 121-131. birkenmajer. k. & zastawniak. e. 1986: plant remains from the dufayel island group (early tertiary’?), king george island. south shetland islands (west antarctica). acrci p d a e o b o r . chun, h. y., chang. s. g. & lee, j . i. 1994: biostratigraphic study on the plant fossils from the barton peninsula and adjacent areas. j . paleonrol. soc. koreci /o( / ), 69-81. kim et al. 2000: polar rrsenrch 19(2), 251-260 259 davies, r. e. s. 1982: the geology of the marian cove area, king george island and tertiary age for its supposed jurassic volcanic rocks. br. anturcr. surv. bull. 51, 151-166. del valle, r. a., diaz, m. t. & romero. e. j. 1984: preliminary report on the sedimentites of barton peninsula, 25 de mayo island (king george island), south shetland islands. argentine antarctica. contrib. i / u t . aiitn'rt. argent. 308. 1 19. ferguson, d. 1921: geological observations in the south shetland islands, the palmer archipelago and graham land. antarctica. truns. r. soc. edinburgh 5 3 ( l ) , 29-55. hathway, b. & lomas, s. a. 1998: the upper jurassic-lower cretaceous byers group, south shetland islands, antarctica: revised stratigraphy and regional correlations. cretac. res. 1 9 , 4 3 4 7 . hu. s. l., wang, s. s.. sang, h. q. & qiu, j. 1985: an application of the fast-neutron activation dating technique to approach the age of early emplacement of jiuling gmno diorite intrusion of jiangxi province. aciu perrolog. sin. i . 29-34. hu. s. l., zheng, x., molan, e. & birkenmajer. k. 1996: ""ar13'ar and k-ar age datings on the volcanic rocks in northern coast of king george island, west antarctica. korean j . polar res. 7(1). 11-21. jwa. y.-j., park, b.-k. & kim. y. 1992: geochronology and geochemistry of the igneous rocks from barton and fildes peninsulas. king george island: a review. in y. yoshida et al. (eds.): rccenf progress in antcirctic earth scirncr. pp. 439 442. tokyo: terra scientific publishing. kang. p.-c. & jin, m . 3 . 1989: petrology and geologic structures of the barton peninsula. king george island, antarctica. i n h. t. huh et al. (eds.): antcrrctic science: geology and biology. pp. 121-135. seoul: korea ocean research and development institute. kawashita, k. & soliani, e., jr. 1988: a rb-sr isochron diagram for the znosko glacier formation (cardozo cove group), admiralty bay, king george island, antarctica. ser. cienr.. insr. antcirt. chi/. 38, 59-66, kim, h.. cho, m. & lee, j. 1. 1995: low-pressure thermal metamorphism of volcanic rocks i n the barton peninsula, king george island. antarctica. i n y . kim et al. (eds.): the ,fi~urt/i seoul irtternutional symposiuni on anrarcric science geology qf the south shetla~id ldands. pp. 25-27. seoul: korea ocean research and development institute. kim, h., cho. m. 2s lee, j . 1. 2000 (unpubl. ms.): thermal metamorphism of volcanic rocks in the barton peninsula, king george island, antarctica. lee, j.-i., hwang, j., kim, h., kang. c. y., lee, m. j. & nagao, k. 1996: subvolcanic zoned granitic pluton in the barton and weaver peninsulas, king george island. antarctica. in k. moriwalj et al. (eds.): proceedings uf' rhr 15rh n l p r symposium 0 1 1 antcirctic grosciences. pp. 7&90. tokyo: national institute of polar research. pankhurst. r. j. & smellie, j. l. 1983: k-ar geochronology of the south shetland islands, lesser antarctica: apparent lateral migration of jurassic to quaternary island arc volcanism. earth planer. sci. lett. 66, 214-222. park, b.-k. 1989: k-ar radiometric ages of volcanic and plutonic rocks from the barton peninsula. king george island, antarctica. j . geol. sue. koreu 25(3), 4 9 5 4 9 7 . smellie, j. l.. liesa. m.. muiioz, j. a,, sibat, f., pallhs, r. & willan, r. c. r. 1995: lithostratigraphy of volcanic and sedimentary sequences in central livingston island. south shetland islands. antcrrct. sci. 7(1), 99-1 13. smellie. j. l.. pallas, r.. sibat. f. & zheng. x. s. 1996: age and correlation of volcanism in central livingston island, south shetland islands: k-ar geochemical constraints. j . south ainer. earth sci. 9(3/4). 265-272. smellie. j. l., pankhurst, r. j.. thomson, m. r. a. & davies, r. e. s . (eds.1 1984: the geology of the south sherlarid islunds: vi. srratigraphy, geochentistry arid evolution. br. antarct. sun,. sci. rep. 87. so. c.-s., yun. s.-t. & park. m.-e. 1995: geochemistry of a fossil hydrothermal system at barton peninsula, king george island. anrarct. sci. 7, 63-72. steiger, r. h. & jager. e. 1977: subcommission on geochron ology convention on the use of decay constants i n geoand cosmochronology. earth planet. sci. lett. 36, 359-362. tokarski, a. k. 1988: structural analysis of barton peninsula (king george island, west antarctica): an example of volcanic arc tectonics. srud. geol. pol. 95. 53-63. tokarski. a. k., danowski, w. & zastawniak. e. 1987: on the age of fossil flora from barton peninsula. king george island, west antarctica. pol. polar res. 8(3). 293-302. tyrrell. g. w. 1921: a contribution to the petrography of the south shetland islands, the palmer archipelago and the danco land coast, graham land. antarctica. t r m s . r. soc. edinburgh 53, 57-79. willan, r. c. r., pankhurst, r. j. & hervc, f. 1994: a probable early triassic age for the miers bluff formation, livingston island. south shetland islands. a r m r c r . sci. 6 . 4 0 1 3 0 8 . york, d. 1969: least-squares fitting of a straight line with correlated errors. earth plfinet. sci. lett. 5. 320-324. zastawniak, e. 1981: tertiary leaf flora from the point hennequin group of king george island (south shetland islands, antarctica): preliminary report. stud geoliig. pol. 72, 97-108. zheng. x. s., hu, s. l., liu, j . q. & sabat, f. 1997: new 4"ar/37"ar age evidence for the cretaceous volcanic rocks of the mount bowles formation in livingston island, south shetland islands. chin. j . polar sci. n(2j. 89-95. zheng, x. s., sang, h. q.. qiu. j., liu. j. q.. lee, j.-i. & hwang, j. 1998: isotopic age of the volcanic rock in byers peninsula, livingston island, west antarctica. chin. j . polar re.$. 10(1), 1-10. 260 geochronologic e v i d e n c e f o r early cretaceous volcanic activity on barton peninsula first observations of emperor penguins on horseshoe island, antarctica research note first observations of emperor penguins on horseshoe island, antarctica sinan yirmibesoglu1,2 and burcu ozsoy1,2 1scientific and technological research council of türkiye, polar research institute, kocaeli, türkiye 2maritime faculty, istanbul technical university, istanbul, türkiye abstract this note reports observations of two moulting emperor penguins (aptenodytes forsteri) on horseshoe island, west antarctica, during the seventh turkish antarctic expedition in february 2023. this is the first time this species has been documented on this island. emperor penguins largely depend on fast-ice to breed and moult. the antarctic peninsula hosts few emperor penguin colonies. horseshoe island has become one of the northernmost points along the western antarctic peninsula where emperor penguins are documented to moult. keywords aptenodytes forsteri; sea ice; antarctic peninsula; marguerite island; moult; ice-dependent species abbreviations gnss: global navigation satellite system tae vii: seventh turkish antarctic expedition   citation: polar research 2023, 42, 9556, http://dx.doi.org/10.33265/polar.v42.9556 copyright: © 2023 sinan yirmibesoglu & burcu ozsoy. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published 31 july 2023 competing interests and funding: the authors report no conflict of interest. correspondence: sinan yirmibesoglu, scientific and technological research council of türkiye, polar research institute, baris mah. no. 1, 41470, gebze, kocaeli, türkiye. e-mail: yirmibesoglu16@itu.edu.tr   introduction the emperor penguin (aptenodytes forsteri) is the heaviest and tallest penguin species (stonehouse 1953) and is listed as near threatened (birdlife international 2020). emperor penguins may have been seen during james cook’s second voyage in the 18th century (cook & furneaux 1777), and the first colony was discovered in 1902 by members of the british national antarctic expedition (discovery expedition), under the leadership of robert falcon scott (wienecke 2010). requiring fast ice to breed and raise their young (barbraud & weimerskirch 2001; jenouvrier et al. 2009) and rarely observed on land (kooyman et al. 2000), emperor penguin colonies are located around the perimeter of the antarctic continent (trathan et al. 2011; fig. 1), including the western and eastern coasts of the antarctic peninsula (fig. 1). the northernmost colony, discovered in 1997, is on snow hill island (57.46°s, 64.52°w), on the eastern side of the peninsula. it numbered about 4000 pairs when its population was at its highest documented level in november 2004 (coria & montalti 2000; wienecke 2010), but comprised only 2700 pairs in december 2018 (schiel et al. 2019). jason peninsula (66.01°s, 60.67°w) also in the eastern part of the antarctic peninsula, is home to a second colony (fretwell et al. 2014). on the western side of the peninsula, a colony established itself north of rothschild island (69.52°s, 72.23°w). on emperor island, one of the dion islands, in marguerite bay, the small colony (ca. 150 pairs) discovered in 1948 (stonehouse 1953) had disappeared by 2009, likely because of climate change (trathan et al. 2011). according to a recent remote sensing study, 62 emperor penguin colonies are still active in antarctica and four no longer exist (fretwell & trathan 2021). fig. 1 locations of emperor penguin colonies on antarctica, compiled from fretwell & trathan (2009); trathan et al. (2011); younger et al. (2017) and fretwell & trathan (2021), using a base map from the quantarctica geographical information system software programme (matsuoka et al. 2021). this note reports the first documented observations of emperor penguins on horseshoe island, about 60 km east of emperor island, in marguerite bay, western antarctic peninsula. two adults were observed to moult there in february 2023 by members of the tae vii. study area horseshoe island lies about 3.5 km west of the antarctic peninsula, in marguerite bay (figs. 1, 2). it hosts base y station, a former british research station, built in 1955 and since 2019, the turkish scientific research camp (yirmibesoglu et al. 2022). tourist cruise ships pass through the area; three were observed during tae vii. also observed on horseshoe island during the expedition were adélie penguins (pygoscelis adeliae), chinstrap penguins (p. antarcticus), south polar skuas (stercorarius maccormicki), crabeater seals (lobodon carcinophaga), fur seals (arctocephalus pusillus) and antarctic terns (sterna vittata). fig. 2 (a) image taken from nasa’s terra satellite modis (moderate resolution imaging spectroradiometer) instrument, showing almost full sea-ice coverage in the bays of horseshoe island (circled) on 27 august 2022 (nasa 2022). (b) sentinel 2 satellite image showing the sea ice remaining in lystad bay (circled) on 17 november 2022. horseshoe island is surrounded by first-year sea ice in the winter (fig. 2a; table 1). there was no sea ice around horseshoe island on 18 february 2023. lystad bay, where the emperor penguins were observed, gaul cove and sally cove were free of sea ice, apart from a few small icebergs (fig. 3). table 1 monthly sea-ice coverage in lystad bay and the approaching side from the west to horseshoe island from open water from january 2022 to february 2023. the sea-ice coverage was interpreted from terra/modis and sentinel 2 satellite images (nasa worldview 2022; copernicus open access hub 2023). months sea-ice coverage (average %) lystad bay sea-ice coverage (average %) approach to horseshoe island jan 2022 0 0 feb 2022 0 0 mar 2022 0 2 apr 2022 0 5 may–jula up to 100 up to 100 aug 2022 55 72 sep 2022 45 57 oct 2022 30 70 nov 2022 0 6 dec 2022 0 0 jan 2023 0 0 feb 2023 0 0 awinter months. fig. 3 sentinel-2 satellite image of horseshoe island, on 18 february 2023, the day of the first emperor penguin observation reported herein. white dots in the water are icebergs. observations on 18 february, a moulting emperor penguin (figs. 4, 5a) was observed standing on a cliff overlooking lystad bay (67.83°s, 67.24°w) at what is marked as observation area 1 in fig. 2. the cliff is stair-like, with rock ‘steps’ that are 1–2 m high (fig. 4). the penguin stood at least 15 m a.s.l., about 50 m from the gnss station solar panels and 250 m south of the turkish scientific research camp. fig. 4 the location of the first emperor penguin in relation to infrastructure on the island. (photo: captain sinan yirmibesoglu.) fig. 5 the (a) first and (b) second emperor penguins observed. (photo: captain sinan yirmibesoglu.) the bird was photographed and videotaped with a professional canon camera equipped with a 300 mm telephoto lens, while a distance of at least 15 m was maintained to avoid disturbance, because they are easily stressed (see burger & gochfeld 2007). the bird was approached from the leeward side and large rocks were used for cover. research-related drone usage was cautious. with all these precautions, the bird appeared not to be disturbed. it had progressed about halfway through its moult. its flippers were fully moulted, while its breast, upper back, head and lowest body parts still had old feathers. fallen feathers were on the ground in the area. at least five adult south polar skuas were seen within 50 m of the penguin on the first observation day. skuas are the main predators of penguin chicks in antarctica on land but are not a threat to adults (pacoureau et al. 2019). two days later, the penguin had moved 40 m to the north. moulting had advanced on the neck and head. on 22 february, four days after the first bird was observed, a second emperor penguin (fig. 5b) was spotted, about 250 m away from the first one in the upper part of the cliff, at the location labelled observation area 2 in fig. 2. this spot is subject to strong winds on account of the lack of natural obstructions. during the observation, the penguin walked around, and a few skuas and antarctic terns seemed to watch it. this second penguin was also moulting, in a slightly more advanced state than the first one. discussion consistent with our observations, adult emperor penguins generally moult in february (fretwell & trathan 2021). however, our observations provide an example of emperor penguins moulting on land, whereas this species usually moults on fast ice or pack ice, selecting ice platforms that stay intact throughout the month-long moult so that the birds do not have to enter the water (kooyman et al. 2000; kooyman et al. 2004). satellite images showed that horseshoe island was completely surrounded by sea ice in the winter of 2022 (fig. 2), giving penguins easy access to the island. lystad bay had been ice-free since november 2022, as was the approach to the island from the west. perhaps the penguins came to the area to moult. the emperor penguins probably came to horseshoe island from the colonies south of the island rather than those on the eastern side of the antarctic peninsula (fig. 1). the penguins may have come from rothschild island, 400 km away, which is the active colony closest to horseshoe island. emperor penguins can travel hundreds of kilometres (croxall & davis 1999; thiebot et al. 2013; schiel et al. 2019) and juveniles are known to migrate even greater distances (thiebot et al. 2013). diverse sea-ice related studies have demonstrated that sea ice is being affected by climate change (newman et al. 2019; lavergne et al. 2022), which threatens penguin habitat (younger et al. 2017). our observations add to the few sightings of emperor penguins on dry land (see kooyman et al. 2000) and make horseshoe island one of the northernmost places along the western antarctic peninsula where emperor penguins have been seen during moulting. the turkish antarctic expeditions will continue to monitor horseshoe island for more penguins. we recommend that environmental protocols for tourists on horseshoe island, particularly around base y, which is a site of historic significance, should take into account the possible presence of moulting emperor penguins. emperor penguins have been shown to change their movements when they notice people within 22.8 m (burger & gochfeld 2007), so keeping a distance of at least 30 m is advisable. acknowledgements this study was carried under the auspices of presidency of the republic of türkiye, under the responsibility of the ministry of industry and technology and under the coordination of the scientific and technological research council of türkiye, polar research institute. the authors thank drs burak karacık and atilla yılmaz for their discovery on the island. they would like to thank the norwegian polar institute for offering the quantarctica programme free of charge. the authors appreciate the open data policy of nasa worldview and copernicus sentinel-2. references barbraud c. & weimerskirch h. 2001. emperor penguins and climate change. nature 411, 183–186, doi: 10.1038/35075554. birdlife international 2020. aptenodytes forsteri. the iucn red list of threatened species 2020. accessed on the internet at https://dx.doi.org/10.2305/iucn.uk.2020-3.rlts.t22697752a157658053.en on 27 march 2023. burger j. & gochfeld m. 2007. responses of emperor penguins (aptenodytes forsteri) to encounters with ecotourists while commuting to and from their breeding colony. polar biology 30, 1303–1313, doi: 10.1007/s00300-007-0291-1. cook j. & furneaux t. 1777. a voyage towards the south pole, and round the world: performed in his majesty’s ships the resolution and adventure, in the years 1772, 1773, 1774, and 1775. vols. 1 & 2. 2nd edn. london: w. strahan and t. cadell. copernicus open access hub 2023. copernicus sentinel-2 data, processed by esa 2002. accessed on the internet at https://scihub.copernicus.eu/on 26 march 2023. coria n.r. & montalti d. 2000. a newly discovered breeding colony of emperor penguins aptenodytes forsteri. marine ornithology 28, 119–120. croxall j.p. & davis l.s. 1999. penguins: paradoxes and patterns. marine ornithology 27, 1–12. fretwell p.t. & trathan p.n. 2009. penguins from space: faecal stains reveal the location of emperor penguin colonies. global ecology and biogeography 18, 543–552, doi: 10.1111/j.1466-8238.2009.00467.x. fretwell p.t. & trathan p.n. 2021. discovery of new colonies by sentinel2 reveals good and bad news for emperor penguins. remote sensing in ecology and conservation 7, 139–153, doi: 10.1002/rse2.176. fretwell p.t., trathan p.n., wienecke b. & kooyman g.l. 2014. emperor penguins breeding on iceshelves. plos one 9, article no. e85285, doi: 10.1371/journal.pone.0085285. jenouvrier s., caswell h., barbraud c., holland m., strœve j. & weimerskirch h. 2009. demographic models and ipcc climate projections predict the decline of an emperor penguin population. proceedings of the national academy of sciences of the united states of america 106, 1844–1847, doi: 10.1073/pnas.0806638106. kooyman g.l., hunke e.c., ackley s.f., van dam r.p. & robertson g. 2000. moult of the emperor penguin: travel, location, and habitat selection. marine ecology progress series 204, 269–277, doi: 10.3354/meps204269. kooyman g.l., siniff d.b., stirling i. & bengtson j.l. 2004. moult habitat, preand post-moult diet and post-moult travel of ross sea emperor penguins. marine ecology progress series 267, 281–290, doi: 10.3354/meps267281. lavergne t., kern s., aaboe s., derby l., dybkjaer g., garric g., heil p., hendricks s., holfort j., howell s., key j., lieser j.l., maksym t., maslowski w., meier w., muñoz-sabater j., nicolas j., özsoy b., rabe b., rack w., raphael m., de rosnay p., smolyanitsky v., tietsche s., ukita j., vichi mj., wagner p., willmes s. & zhao x. 2022. a new structure for the sea ice essential climate variables of the global climate observing system. bulletin of the american meteorological society 103, e1502–e1521, doi: 10.1175/bams-d-21-0227.1. matsuoka k., skoglund a., roth g., de pomereu j., griffiths h., headland r., herried b., katsumata k., le brocq a., licht k., morgan f., neff p.d., ritz c., scheinert m., tamura t., van de putte a., van den broeke m., von deschwanden a., deschamps-berger c., van liefferinge b., tronstad s. & melvær y. 2021. quantarctica, an integrated mapping environment for antarctica, the southern ocean, and sub-antarctic islands. environmental modelling & software 140, article no. 105015, doi: 10.1016/j.envsoft.2021.105015. nasa worldview 2022. corrected reflectance true color (bands 1-4-3). accessed on the internet at https://worldview.earthdata.nasa.gov/ on 26 march 2023. newman l., heil p., trebilco r., katsumata k., constable a., van wijk e., assmann k., beja j., bricher p., colemans r., costa d., diggs s., farnet r., fawcett s., gille s.t., hendry k.r., henley s., hofmann e., maksym t., mazloff m., meijers a., meredith m.m., moreau s., ozsor b., robertson r., schloss i., schofield o., shi j.x., sikes e., smith i.j., swart s., wahlin a., williams g., williams m.j.m., herraiz-borreguero l., kern s., liesers j., massom r.a., melbourne-thomas j., miloslavich p. & spreen g. 2019. delivering sustained, coordinated, and integrated observations of the southern ocean for global impact. frontiers in marine science 6, article no. 433, doi: 10.3389/fmars.2019.00433 pacoureau n., delord k., jenouvrier s. & barbraud c. 2019. demographic and population responses of an apex predator to climate and its prey: a long‐term study of south polar skuas. ecological monographs 89, e01388, doi: 10.1002/ecm.1388. schiel r., güpner f. & spitzenberger h.j. 2019. population size and condition of the emperor penguin aptenodytes forsteri colony of snow hill island, weddell sea, antarctica: observations from 29 december 2018. marine ornithology 47, 189–192. stonehouse b. 1953. the emperor penguin aptenodytes forsteri gray. i. breeding behavior and development. falkland islands dependencies survey scientific reports 6. london: her majesty’s stationery office. thiebot j.b., lescroël a., barbraud c. & bost c.a. 2013. three-dimensional use of marine habitats by juvenile emperor penguins aptenodytes forsteri during post-natal dispersal. antarctic science 25, 536–544, doi: 10.1017/s0954102012001198. trathan p.n., fretwell p.t. & stonehouse b. 2011. first recorded loss of an emperor penguin colony in the recent period of antarctic regional warming: implications for other colonies. plos one 6, article no. e14738, doi: 10.1371/journal.pone.0014738. wienecke b. 2010. the history of the discovery of emperor penguin colonies, 1902–2004. polar record 46, 271–276, doi: 10.1017/s0032247409990283. yirmibesoglu s., oktar o. & ozsoy b. 2022. review of scientific research conducted in horseshoe island where potential place for turkish antarctic base. international journal of environment and geoinformatics 9, 11–23, doi: 10.30897/ijegeo.1018913. younger j.l., clucas g.v., kao d., rogers a.d., gharbi k., hart t. & miller k.j. 2017. the challenges of detecting subtle population structure and its importance for the conservation of emperor penguins. molecular ecology 26, 3883–3897, doi: 10.1111/mec.14172. doi:10.3402/polar.v32i0.22576 b o o k r e v i e w review of shipwreck at cape flora: the expeditions of benjamin leigh smith, england’s forgotten arctic explorer, by p. j. capelotti (2013). calgary: university of calgary press. 269 pp. isbn 978-1-55238-705-4. research for this biography has taken the author from the united states to various parts of the united kingdom and to franz josef land, as well as drawing on his field experiences from svalbard. his thoroughness in digging up material has produced a detailed account of the rather amazing life of the british eccentric benjamin leigh smith. leigh smith’s life story has two distinctive themes, which both separately exceed the bounds of normality and both would merit a detailed and separate study of their own. on the one hand, there is his experience as an arctic explorer. superficially, he can easily be placed together with other british gentlemen yachters and hunter/explorers, such as james lamont (seasons with the sea-horses, yachting in the arctic seas) and lord dufferin (letters from high latitudes), who have contributed through their highly readable expedition accounts to the history of arctic exploration. sadly, leigh smith never wrote his own accounts of the five expeditions he made between 1871 and 1882 to svalbard, jan mayen and franz josef land. unlike most other explorers, he shunned the public eye, refused to personally hold presentations, receive accolades or publish any accounts. it was left to others to accept honours and medals on his behalf and to write of the exceptional exploratory voyages he devised and led. in this way, he can partly be compared with the silent and stoic otto sverdrup who in 1898�1902 led his own very successful scientific and exploratory expedition to what are now canada’s high arctic islands. sverdrup, however, did manage to have an account of the four-year expedition published (new land). to continue with leigh smith’s arctic voyages before turning to his unusual private life, he was 43 years old before he decided that he would devote some of his extensive wealth and free time to voyages in the far north. during these expeditions, he did a considerable amount of scientific work, particularly concerning temperature soundings at various depths that was pioneer work within the field at the time. on his 1871 voyage to north-east svalbard, he added 33 new place names, including 22 islands, to the map and later in franz josef land he continued filling in the map of the south-west area of this complicated archipelago. it can be noticed that the original edition of the norwegian publication the place-names of svalbard credits the norwegian captain of leigh smith’s expedition ship, e. a. ulve, with first reaching the summit of tumlingodden, while perhaps the expedition leader, leigh smith, should have received the credit (capelotti, p. 67). in 1873, he fulfilled a promise made to the finnish�swedish scientist and explorer adolf erik nordenskiöld the year before and sailed to the north of svalbard to offer assistance to nordenskiöld’s 1872�73 expedition if deemed necessary. it was indeed necessary and the large amounts of food and drink that leigh smith turned over to nordenskiöld earned him a swedish medal for helping to save the expedition. leigh smith’s final voyage, to franz josef land for the second time in 1881, is what the title of capelotti’s book is all about. leigh smith’s purpose-built ship eira became icebound off cape flora and was crushed and sank just (page number not for citation purpose) correspondence susan barr, directorate for cultural heritage, dronningens gate 13, p.o. box 8196, no-0034 oslo, norway. e-mail: susan.barr@ra.no polar research 2013. # 2013 susan barr. this is an open-access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2013, 32, 22576, http://dx.doi.org/10.3402/polar.v32i0.22576 http://www.polarresearch.net/index.php/polar/article/view/22576 http://dx.doi.org/10.3402/polar.v32i0.22576 off the shoreline*but not before the crew had managed to save a more than adequate amount of provisions and equipment. the 25 men built a wintering hut, flora cottage, of stones, spars and sailcloth and spent a not too uncomfortable winter before managing to repeat payer’s and weyprecht’s 1874 retreat from franz josef land to novaya zemlya in small boats. the remains of flora cottage were still visible in 1996, but coastal erosion has now washed them into the sea. altogether leigh smith’s voyages, scientific work, geographical exploration and place naming, relief of nordenskiöld’s expedition and shipwreck at cape flora place him high up on the list of solid and memorable arctic explorers. as was said in the royal geographical society in london in 1881 (leigh smith himself was as usual not present), ‘‘the name of mr. leigh smith would be handed down to futurity as one of the great polar explorers of the victorian age’’ (quoted in capelotti, p. 175). yet the undertitle to capelotti’s book*england’s forgotten arctic explorer*is not without a ring of truth, even though book titles announcing one or other ‘‘forgotten’’ polar explorer are inclined to produce a large yawn in this reviewer. while mentioning the title, it is a mystery why the author (or perhaps the publisher?) has chosen to title this biography, which encompasses so much in the life of an amazing person, from just one event in his life, dramatic as it was. i wonder how many potential readers can place cape flora on the map before delving into the book. the front cover illustration is rather fussily composed of several superimposed images, but the vignettes which introduce each chapter are excellent. and the other side of leigh smith’s life? all will not be revealed here, but he had an extraordinary family life with some questionable relations concerning both his father, who seems to have conducted a social experiment with various families on the side, and concerning his own affection for the young girls in his family. it was interesting to learn that he was florence nightingale’s cousin, and that his sisters were extraordinary in their own right. much of the information about leigh smith’s private life can seem a little gossipy, but the author has done his research and has a reasonable basis for the details he reveals. capelotti writes with an easy, interesting and at times humorous pen. he has an excellent literary style that keeps the text flowing through the various episodes at home and out in the north. his obvious knowledge of arctic exploration history has tempted him too far in relating in detail other previous expeditions such as those of phipps, parry, kane, lamont and payer and weyprecht, which should have been cut down to short outlines. it is easy for the reader to become absorbed in these other histories and almost forget the actual subject of the book. at the same time one can feel some impatience at wanting to get back to more details of leigh smith’s home life! being the author of jan mayen’s history (1991), i must point out one mistake i noticed on page 82. leigh smith in 1872 was not ‘‘the first british explorer to set foot on the island [jan mayen] since william scoresby, jr., in august of 1817.’’ lord dufferin had managed to scramble ashore there in 1856. i am delighted that this biography of benjamin leigh smith has been researched and written so well and that the details of the life of this little-known (but perhaps not ‘‘forgotten’’) arctic explorer are now made available to a wider public. the readership should include both polar aficionados and those interested in the eccentric lives of the british-landed gentry of the 19th century. references barr s. 1991. jan mayen: norges utpost i vest. øyas historie gjennom 1500 år. (jan mayen: norway’s western outpost. the island’s history through 1500 years.) oslo: schibsted. (reprinted 2003 by author.) dufferin, lord. 1857. letters from high latitudes. london: john murray. lamont j. 1861. seasons with the sea-horses. london: hurst and blackett. lamont j. 1876. yachting in the arctic seas. london: chatto and windus. norway’s svalbard and arctic ocean survey 1942. the placenames of svalbard. skrifter om svalbard og ishavet 80. oslo: norway’s svalbard and arctic ocean survey. (reprinted 1991 by norwegian polar institute.) sverdrup o. 1904. new land: four years in the arctic regions. london: longmans, green and co. book review 2 (page number not for citation purpose) citation: polar research 2013, 32, 22576, http://dx.doi.org/10.3402/polar.v32i0.22576 http://www.polarresearch.net/index.php/polar/article/view/22576 http://dx.doi.org/10.3402/polar.v32i0.22576 numerical simulation of salinity anomaly propagation in the nordic seas and the arctic ocean riidiger gerdes & cornelia koberle we investigate the response of the nordic seas-arctic ocean system to surface freshwater f l u x anomalies that we regard as typical for long-term atmospheric variability. we employ response experiments with a coupled sea ice-ocean model where we introduce a surface freshwater f l u x anomaly ( a ) over the norwegian sea and (b) in the laptev sea. case a offers an explanation for the intermediate depth salinity changes observed in the aniundsen basin. the signal observed there belongs to an original perturbation that, according to the model, occurred around a decade earlier. salinity fluctuations in the laptev sea could play a role in changes in the near surface salinity in the amundsen basin. r. gerdes & c, kiiberle, alfred wegener imtitirre ,fiw polar md mrrririe resmrrh, am h a n d e l h f e n 12, 0 2 7.770 bremer/iciven, gerniuny introduction comparing results from two expeditions into the eurasian basin in 1991 and 1996, schauer, rudels et al. (unpubl. ms.) identified a warming from 1991 to 1996 in the core of the atlantic water at around 2 0 0 m and reduced salinity in a layer between 500 m and 1200 m deep in the amundsen basin. the latter is attributed to an increased outflow from the barents sea that feeds into a boundary current along the rim of the eurasian basin (gerdes & schauer 1997; schauer, muench et al. 1997). schauer, rudels et al. (unpubl. ms.) also confirm the disappearance detected by steele & boyd ( 1998) of the arctic halocline in the central eurasian basin during recent years. model experiments are an important tool to investigate the relations between climate system components, their individual responses to external forcing, feedbacks, and internal modes of varia bility. here we investigate the fate and possible influence of salinity anomalies that we regard as typical for long-term variability in the nordic seas-arctic ocean system using a coupled sea ice-ocean model. in particular, we examine the response to ( a j a precipitation anomaly over the norwegian sea that represents the main freshwater flux signal associated with the nao according to dickson et al. (in press) and (b) a freshwater flux anomaly in the laptev sea. the latter can be thought of as being generated by long-term wind anomalies associated with the nao that influence sea ice formation and thus brine release in the laptev sea. increased river run-off during periods of anomolously high precipitation over the catch ment area would also lead to such a freshwater flux anomaly. modelling these surface flux anomalies is not intended to investigate the response of the ocean to the nao; this involves, among other variables, changes in the wind and air temperature. here, we rather try to isolate the effect of a single element of the nao forcing on sea ice and the ocean. model description and experimental design the ocean model derives from the geophysical fluid dynamics laboratory modular ocean model (mom-2: pacanowski 1995). the model. domain is shown in fig. 1. bottom topography is derived by horizontal averaging from the etopo5 data set of the national geophysical data center (1988). modifications were made in denmark strait and the faeroe bank channel area to retain the sill depths of the passages. gerdes & koberle 1999: p o l a r resenrch l 8 ( 2 ) , 159i66 159 i n 0 0 p 0 n 8 6 8 a 8 03 8 l 0 8 i i i i i cn + n u 4 o % ~ ~ ~ o o o o o 4 0 n 30n 20n 1 on e q 10s fig. i. model domain and bottom topography for the numerical model used in this study. the model encompasses the atlantic north of approximately 2 0 s . including the whole arctic ocean. the southern boundary is a closed wall. to avoid the singularity of geographical spherical coordinates at the pole the model is formulated on a rotated spherical grid where the equator coincides with the geographical 3 0 w meridian. the pole of the grid lies at 60"e on the geographical equator. the horizontal resolution is 1" by 1' in the rotated grid, resulting in nearly equal spacing of about 100 km in both horizontal directions i n the whole arctic ocean. i n the vertical. the model contains 19 unevenly spaced levels. the locations of freshwater flux anomalies are indicated for experiment a (off norway) and b (laptev sea). the bold line along model longitude 5"w indicates the position of the section shown in fig. 3. 8 0 w 60w 40w 20w gm the integration starts from rest and potential temperatures and salinities taken from levitus & boyer (1994a, b). north of 75'" initial data were taken from levitus ( 1982) because of deficiencies of the newer climatology in the arctic. the integration periods for experiments reported here are 20 years, 10 years of spin-up followed by a response experiment of equal length. thermody namic equilibrium is not reached and not intended for these numerical experiments. we have chosen this relatively short integration time so that the adjustment processes are modelled against a realistic background state, close to the climatolo gical distributions that were used as initial conditions. the use of an additional tracer for salinity anomaly and a reference experiment without surface flux anomalies enables us to separate model drift and the response to forcing anomalies. the ocean model is coupled with a dyna mic-thermodynamic sea ice model that has been developed by harder (1997) from the original hibler (1979) model and employs a viscous-plastic rheology. the models are coupled following the procedure devised by hibler & bryan (1987). forcing data are derived from ecmwf data. climatological monthly data are generated for surface air temperature, dew point temperature, cloudiness, precipitation and wind speed. these values are interpolated onto the current time in the model. wind stress is treated similarly: however, here daily variability is added to make the simulation of sea ice more realistic. the procedure of generating the daily variability for a climatolo 160 numerical simulation of salinity a n o m a l y propagation gical mean year is described by roske (in prep.). it should be noted that the climatology is based on the period 1979 to 1993. according to the nomenclature of proshutinsky & johnson (1997) this whole period (with the only exception of the years 1985 and 1987) belongs to the cyclonic circulation regime. the forcing is thus representa tive for the 80s and early 90s, and less so for earlier periods. in addition to potential temperature and salinity, the ocean model carries another tracer represent ing the salinity anomaly. the tracer is initialized as zero everywhere and it obeys a no flux condition at the horizontal walls and the bottom. the no flux condition also applies at the surface except for the areas marked in fig. 1: off norway and i n the laptev sea in experiments a and b, respectively. in experiment a a fresh water flux anomaly of 3 m d d a y is switched on during three winter months (jfm) for three consecutive years follow ing the 10 year spin-up. i n experiment b we consider three consecutive winters with reduced sea ice formation of 1 m which represents a reduced salt flux into the ocean that is equivalent with an anomalous freshwater flux of 11 mm/day over the winter period. it should be noted that the salinity anomaly tracer is active in both experi ments, i.e. it is added to the salinity before the equation of state is evaluated. a reference experiment without any anomalous surface fresh water fluxes accompanies the two response experiments and can be used to identify dynamical effects of the salinity anomalies like changes in surface density, currents and mixed layer depth. results the distribution of salinity anomaly due t o the higher precipitation in the nordic seas (experiment a) in fig. 3 shows the propagation from the source area into the barents sea and subsequently into the northern kara sea. as soon as the anomaly enters the barents sea. surface concentrations drop to less than 0.03 psu. large northward velocities carry the induced salt anomaly out of the source area and no accumulation of freshwater occurs. deep winter convection reaches the bottom in most parts of the barents sea and mixes the originally surface-trapped anomaly over a column 200-300 m thick. the dilution of the signal due to horizontal and vertical transports prevents a strong local density anomaly and the dynamical effect of the anomaly is small. the salt anomaly behaves like a passive tracer that is advected and mixed with the unaltered circulation and convection in the ocean. a similar representation for the 3 0 0 m depth level (fig. 3) shows the exit of the anomaly from the barents sea through the st. anna trough starting in the second year after the last anomalous winter precipitation off norway. small amounts of the anomaly appear west of the st. anna trough as a consequence of a direct inflow from fram strait. in the following years, the anomaly takes part in the cyclonic circulation around the eurasian basin and turns northward away from the boundary at the lomonosov ridge. it continues toward fram strait . at greater depths, concentrations are lower and the inflow through fram strait gains relative importance. however, even at greater depths the outflow from the barents sea appears in the vicinity of the st. anna trough before the fram strait signal arrives at that location. the anomaly mainly follows the pathway of barents sea outflow as described by schauer, muench et al. ( 1997) and the numerical model of gerdes & schauer (1997). because the outflow from the barents sea forms a thick layer in the arctic, the salt anomaly is spread over a large vertical distance. the pathway is strongly affected by topographic structures, especially the lomonosov ridge. it takes about five years for the anomaly to reach the north pole. a different picture emerges for the salinity anomaly in the laptev sea. compared to the norwegian sea, the circulation in the laptev sea is slow. thus in experiment b a large part of the accumulated freshwater remains in the laptev sea. stratification is stable even during winter and no deep convection occurs, in contrast to conditions in the barents sea. thus, surface salinity anoma lies reach increasingly large values during the three anomalous winter conditions prescribed in experiment b. the surface salinity reaches 2 psu in the last year of the anomalous surface forcing (fig. 4). it spreads into the interior of the arctic ocean along the oceanic transpolar drift (to be distin guished from the sea ice transpolar drift that presents a more direct connection to fram strait). the interior low salinity signal establishes within one year. concentrations there reach 0.4 psu before the anomaly vanishes again after the cessation of the supply from the laptev sea. the gerdes & koberle 1999: polrir resmrch i k ( z ) , 159-166 161 1 1 lrl c' 1 ' 1 l '\ 'i hj 3 m c.. 13 r'i f i g . ?. winter mean (january through march) surface distribution of the salinity anomaly i n experiment a for ( a ) the last year with anomalous precipitation ( = 1998). (h) 1999. ( c ) 2000, (d) 2001. contour interval is 0.005. axis labels refer to the rotated model grid. 162 numerical simulation of salinity anomaly propagation 1 4, t ,l c 4 pi n n m l , l 77 f i g . 3. winter mean distribution of the salinity anomaly in experiment a at 300 m depth for (a) the last year with anomalous precipitation (= 1998), (b) 2000. (c) 2002. (d) 2005. contour interval in (a) and (b) is 0.002 and i n (c) and (d) is 0.001. axis labels refer to the rotated model grid. gerdes & koberle 1999: polur research z8(21, 159-166 163 l i l 77 i fig. 4. winter mean surface distribution of the salinity anomaly i n experiment b for (a) the last year with anomalous freshwater flux ( = 1998), (b) 1999. (c) 2000. (d) 2001. contour interval is 0.1. axis labels refer to the rotated model grid. i64 numerical simulation of salinity anomaly propagation anomaly i n case b remains at the surface ( i t is confined to the upper 150 m) and is not transferred to deeper layers. consequently, the surface density anomaly is much stronger than in case a. discussion and conclusion surface forcing anomalies selected for our experiments were similar to certain aspects of recent changes in atmospheric forcing and it is appropriate to compare the model results with observations of recent changes in the hydro graphic structure of the upper eurasian basin. steele & boyd (1998) and schauer, rudels et al. (unpubl. ms.) describe a retreat of the cold halocline layer from the amundsen basin back into the makarov basin. this change is attributed to a change in sea ice drift patterns or a diversion of freshwater from the shelves into a more easterly route. our experiment b indicates that freshwater anomalies that are generated over the siberian shelf seas by anomalous sea ice forma tion and/or river run-off can affect the surface salinity along the oceanic transpolar drift. how ever, the part of the original anomaly that propagates into the interior is small; maximum salinity perturbations in the makarov basin are 0.2psu, one order of magnitude smaller than in the laptev sea. observed changes i n the amundsen basin are around 0.3 psu (schauer, rudels et al. unpubl. ms.). it has to be kept i n mind that our response experiment only considers a freshwater flux anomaly and does not take into account the changes in the wind field between negative and positive phases of the nao or associated with a longer-term trend. furthermore. the wind forcing used here is biased toward the cyclonic regime of the arctic ocean circulation (proshutinsky & johnson 1997) because i t is based on wind data from the period 1979 to 1993. the effect of wind related changes in oceanic circulation might well be stronger than the freshwater flux anomaly effect in our experiment where the salinity anomaly behaves more or less passively once i t has left the laptev sea. schauer. rudels et al. (unpubl. ms.) find reduced density between 1 0 0 m and 1500ni and reduced salinity between 500 m and 1500 in i n the amundsen basin when comparing data from 1996 to observations taken five years earlier. a warming signal in the atlantic layer indicates a stronger contribution of atlantic water in that area. however, the salinity changes are too low to compensate the density effect of the temperature as would be expected for just a stronger inflow of atlantic water through fram strait. apparently, water mass modifications affecting primarily salinity are necessary to explain the observed changes. these could be melting of sea ice, increased precipitation and run-off. the presence of a salinity anomaly at depth hints at a source of the anomaly located in or upstream of the barents sea because water recently in contact with the surface is injected into intermediate depths primarily at the outflow from the barents sea at the st. anna trough. results of experiment a show that a precipitation anomaly in the nordic seas, which is typical for the difference between high and low index phases of the nao (dickson et al. in press), can lead to large-scale freshening in the barents sea and along the pathway of the barents sea branch of the atlantic inflow into the arctic. a few years after the anomaly, the freshening occupies a 1ooom thick layer east of the st. anna trough and a somewhat shallower layer further along the path towards fram strait. this reflects the slower advection speed in the lower layers and it is conceivable that the deep anomaly will reach the central amundsen basin a few years after the surface signal. the model results suggest a delay between the forcing in the nordic/ barents sea and the arrival in the central amundsen basin of roughly a decade. the salinity anomalies measured at depth in 1996 would thus be the signal of the high nao fresh water forcing of the late 1980s. in experiment a we have not included an increased inflow into the barents sea due to strengthened circulation in the nordic seas. with this we perhaps underestimate the anomaly, as the total forcing is likely to increase the outflow through the st. anna trough and feed a stronger boundary current in the eurasian basin. still, with only one process taken into account, the qualita tive properties of the simulated salinity anomalies are consistent with recent observations in the amundsen basin. acknmvledgenients. this work was i n p a l funded by the bundesininisterium fur forschung und technologie through grant 07 v k v o i and by the european commision mast 111 programme through contract mas3-ct96-0070 (veins). we thank markus harder for providing the sea ice model code and frank roske for supplying the ecmwf forcing data. gerdes & koberle 1999: pnlrrr research i r ( 2 ) . 159-166 165 references dickson, r. r., osborn, t. j., hurrell, j. w.. meincke, j., blindheim, j., adlandsvik, b., vinje. t., alekseev, g . , maslowski, w. & cattle, h. in press: the arctic ocean response to the nonh atlantic oscillation. j . clirnate. gerdes, r. l schauer, u. 1997: large-scale circulation and water mass distribution in the arctic ocean from model results and observations. j . geophjs. res. 102(c4), 8467-8483. harder, m. 1997: roughness, age and drift trajectories of sea ice i n large-scale simulations and their use i n model verifications. ann. glaciol. 25, 237-240. hibler. w. d. 1979: a dynamic thermodynamic sea ice model. j . phys. ocranogr. 9, 8 15-846. hibler. w. d. & bryan, k. 1987: a diagnostic ice-ocean model. j. phys. oceunogr. 7, 987-1015. levitus, s . 1982: cliinutological atlas of the world ocean. noaa pub!. 13. 173 pp. washington, d.c.: us department of commerce. levitus, s . & boyer. t. p. 1994a: world ocean a t h s 1994. vol. 3. snliniry. 99 pp. washington, d.c.: national oceanographic data centerllis department of commerce. levitus, s . & boyer, t. p. 1994b: world ocean atlas 1994. vol. 4. temperature. 117 pp. washington, d.c.: national ocedno graphic data centerrls department of commerce. pacanowski, r. c. 1995: mom 2 docummtatioil, uscr’s guide and reference manual. gfdl ocean group technical report no. 3. 232 pp. princeton, nj: geophysical fluid dynamics laboratoryprinceton university. proshutinsky, a. y. & johnson, m. a. 1997: two circulation regimes of the wind-driven arctic ocean. j . geophys. res. 102(c6), 12493-12514. roske, f. in prep.: ocean model intercomparison project (omip): common forcing and an atlas based on ecmwf reanalysis data. mpi report. hamburg: max-planck-lnstitut fur meteorologie. schauer, u., muench, r. d., rudels, b. & timokhov, l. 1997: impact of eastern arctic shelf waters on the nansen basin intermediate layers. j . geophys. res. 102, 3371-3382. schauer, u., rudels, b., jones, p., anderson, l. g.. muennich, r. d.. bork, b., swift, j. h., ivanov, v. & larson, a.-m. unpubl. ms.: water mass distribution in the eastern eurasian basin and connections with the canadian basin: results from steele, m. & boyd, t. 1998: retreat of the cold halocline layer in the arctic ocean. j . geophjs. res. 103(c5). 10419-10435. acsys-96. 166 numerical simulation of salinity anomaly propagation arctic grazing systems and industrial development: can we minimize conflicts? david r. klein the industrialized world is expanding its search for energy, minerals, timber and other resources into the arctic and adjacent higher latitudes. up to now, large-scale development projects in the arctic and sub-arctic have been few. we can, however, profit from experiences gained from several of these, including oil and gas exploration and development in alaska and on russia’s yamal peninsula, the norilsk metalurgical complex of siberia, alaska’s red dog mine and others. conclusions drawn from these experiences are that industrial impacts on arctic grazing systems can be minimized if the following considerations guide their planning: 1) most of the large development projects that have been undertaken in the north have lacked adequate background information on the grazing systems that they might impact; 2 ) there needs to be recognition by industry and governments for the amount of time required to gather such information and provision made for this; 3) because types of impacts on northern grazing systems that may result from development projects vary depending on whether they involve mining, oil or gas, hydroelectric or other activities, each proposed project must be assessed indepen dently; 4) cumulative effects of multiple projects, often sequentially developed, are seldom addressed by the responsible governments, thus planning for development of an individual project should be within the context of regional and long-range development planning; and 5 ) types and sources of contaminants entering northern ecosystems, threatening the health of northern residents, must also be a major focus of project assessment. d . r. klein, institute of arctic biology, university of alaska fairbanks, irving i bldg., fairbanks, a k 99775 7000, usa. historically, the lands of the arctic and adjacent northern forests experienced few effects of the rapidly developing and expanding industrialized world to the south. but as a consequence of its demand for the energy, mineral, timber and other resources necessary to maintain its production and consumption of material goods, and its growth, the industrialized world is now expanding its search for resources into the arctic and adjacent higher latitudes. such efforts are designed to serve the interests of industry, with little understanding, appreciation or concern for the residents of the north, their cultural, social and economic well being, and the natural environments which have sustained them. it is now time for governments in those countries with lands in the arctic to establish collaboration with industry and residents of the north to assure that northern development pro ceeds only when such activities can take place without major impacts detrimental to the northern environment and the residents dependent upon it. because of the logistic and engineering diffi culties and associated high expenses involved in resource development and extraction in the north, only the larger energy and mining companies have the financial and other resources necessary to undertake northern development ventures. this may facilitate governmental assessment of poten tial environmental impacts, as well as social and economic influences on local residents prior to approval of proposed projects. financial responsi bility for this effort should be shared between industry and government. during development and production phases, governmental monitoring and klein 2000: polar research 19(1), 91-98 91 enforcement of stipulations designed to minimize environmental and socio-economic impacts can be more feasibly dealt with than is the case for smaller scale, more widely scattered, projects. however, large industrial complexes, seeking a maximum return on their investments, have a record of mobilizing their considerable potential political influence on national and regional governments to oppose or constrain the imposition of environ mental or other restrictions on their exploration, development and production activities. learning from existing and proposed development projects although large-scale development projects in the arctic and sub-arctic have been few in contrast to those at lower latitudes, there are several through out the circum-arctic region that have directly or indirectly influenced arctic grazing systems, and from which much can be learned. they offer examples and experiences of value in assessing proposed new projects and for designing guide lines for their development to avoid unnecessary environmental, social and economic impacts. these past and current projects also point up inadequacies in the initial planning that in some cases have led to impacts that could have been avoided or minimized through more conscientious and comprehensive planning in advance of project approval. they also reveal the general lack of knowledge within governments and industry about ecosystems at high latitudes and of the human relationships to them. alaska’s arctic oil development the discovery in 1968 of a giant oil reservoir at prudhoe bay in alaska’s arctic led to a rush by the oil industry to construct a pipeline more than 1000 krn across alaska to an ice-free port to the south so that the oil could be transported to markets. however, construction of the pipeline and development of the oil field were delayed for nearly four years until land entitlement of alaska natives and public land use issues could be resolved by the us congress. the delay in development of this giant project was viewed by the oil industry with understandable frustration, whereas environmental organizations were vocal in their emphasis on the need for adequate assessment of environmental values at risk, demonstration by industry of adequacy of engi neering design for arctic conditions, and devel opment of governmental stipulations and oversight to minimize impacts on the environment. never theless, this delay before governmental authoriza tion could be granted for pipeline construction allowed time for at least superficial environmental studies to be undertaken and for development of environmental stipulations for construction and operation of the pipeline and oil field designed to minimize impacts on the environment. it also allowed for settlement of alaska natives’ claims to land and other entitlements, and for initiation of opportunities for alaska natives to derive eco nomic benefit from the oil development. in retrospect, industry, environmental interests, alaska natives and government all have recog nized that the time that was available between oil discovery and initiation of pipeline and oil field construction resulted in substantial reduction of the environmental impacts associated with the project. whereas the prudhoe bay oil field and associated transalaska pipeline are now viewed as examples of large-scale energy development in the arctic with low environmental impact, this assessment has to be viewed in the context of the times and the magnitude of the project. it is now apparent that there are unanticipated cumulative effects resulting from intensified and expanded oil field development involving proliferation of roads, pipelines and other oil field infrastructure. the consequences for seasonally resident caribou are displacement from calving grounds, obstruction of their movements to and from the coast during the insect season, and gradual abandonment of grazing areas within the oil field, with evidence of reduced body condition of adult females and lowered recruitment rates (cameron et al. 1995). experi ence gained since early development of the prudhoe bay field has led to design and layout of pipelines, roads and other oil field infrastructure so as to reduce the obstruction of movements of caribou and the degree of their abandonment of grazing areas. the complexity of the ecological relationships of caribou to their environment in this region of the alaskan arctic, nevertheless, is only now beginning to be realized. proposed oil exploration and development in north-eastern alaska the coastal plain of alaska’s arctic national 92 arctic grazing systems and industrial development: can we minimize conflicts? wildlife refuge has become the site of proposals for large-scale oil development. as a result, the us gas exploration and devetopnzent on the yamal peninsula congress provided for comprehensive studies to assess the environmental values present and possible impacts of oil development on them. caribou of the porcupine herd, numbering ca. 130 000, and their ecosystem relationships were a major focus of these studies (us fish and wildlife service 1982; garner & reynolds 1983, 1984). companion ecological studies were also carried out in canada o n this international caribou herd (russell et al. 1993). because of the comprehen sive nature of these studies and the time made available for their completion, much has been learned about the importance of vegetation and its phenology in determining the seasonal patterns of use of the land by caribou, especially in relation to the importance of specific calving grounds and summer foraging areas. in addition, the relation ship of the caribou to bears, wolves and other components of the ecosystems involved, including the humans who hunt and are dependent upon caribou, have been examined. as a result of this accumulation of detailed knowledge about an arctic grazing system at the ecosystem level, the us national science foundation funded a project to develop a computer-based interactive model focused on the sustainability of the human communities that have long been dependent on the caribou and the ecosystems that support them. the information that has been gathered in these efforts, and the models of varying potential future community options, will be of the utmost value in empowering these northern peoples to have an equitable voice in authorizing oil development within the calving grounds and summering areas of the porcupine caribou herd (kruse 1999). should oil development be permitted in the future, planning for the oil field and necessary pipelines and roads to minimize impacts on the caribou will be greatly assisted as a result of these efforts. perhaps one of the most valuable outcomes of this example of a comprehensive study of an arctic grazing system has been a recognition by the natural and social scientists and economists involved, and the native stakeholders in the system, of the complexity of the system and of the difficulty of modelling this complexity so that it will have predictive value. those involved in this project have developed a sense of humility regarding our ability to fully understand arctic grazing systems and the human role in their sustainability . exploration and development of extensive gas fields on the yamal peninsula of russia, primarily during the 1980s, while not yet in a production stage, progressed rapidly without assessment of surface values or the potential effects on them and the reindeer grazing system of the nenets people who live in the area. erosion of the sandy soils, once the protective vegetative cover had been lost through road and rail construction, exploration activities and careless use of off road vehicles on the tundra, has resulted in substantial damage and loss of grazing lands for the reindeer (forbes 1997). stocking levels of reindeer on the yamal ranges, however, already exceeded their sustain ability prior to the widespread effects of explora tion and development of the gas fields; thus reindeer grazing pressure was intensified on the remaining areas undisturbed by the petroleum exploration activities. extensive development activities on the yamal peninsula, because of its highly erodible soils and importance for reindeer grazing and the nenets people dependent upon them, should have been preceded by comprehen sive biological and sociological studies of the local grazing system. these could have provided the basis for assessing impacts of the proposed exploration and development activities, and for establishing guidelines and restrictions designed to avoid or minimize the impact. similarly, knowl edge could have been gained about the most appropriate methods of restoring vegetation to areas unavoidably disturbed or damaged in the exploration activities (forbes 1997). involvement of the nenets reindeer herders in the planning process might also have made it possible to schedule development activities and locate trans portation corridors to minimize their effects on seasonal movements and range use patterns of the reindeer, and to avoid displacement of the herders from traditional seasonal camp sites. the norilsk metalurgical complex in the taimyr region of north-western siberia, development of the norilsk metalurgical complex began in the 1930s. it is now the world’s largest producer of nickel and also the world’s largest point source of atmospheric pollution. some aspects of this giant mineral extraction development have had direct impact on both the wild reindeer of the klein 2000 polar research 19(1f, 91-98 93 taimyr herd, numbering in excess of 500 000, and domestic reindeer in several herds throughout the region. the energy source for ore smelting and for power generation was originally coal, but by the late 1960s some hydroelectric power had become available and natural gas pipelines were constructed from the messoyakha field during 1969-1973. this resulted in some immediate reduction in sulfur dioxide and other atmospheric pollutants, but continued growth in the industrial complex in creased the sulfur component of the discharge gases from 5% in 1981 to about 50% by 1989 (vlasova et al. 1991). construction of the first pipeline, and subsequent addition of parallel pipelines laid across the tundra, obstructed the movement of large numbers of the taimyr wild reindeer on their annual migrations between their summer calving and grazing areas and their wintering area's. some of the wild reindeer, unable to cross the pipelines, initially were deflected in their movements into the city of norilsk and the associated mining and smelting complex. the large concentrations of reindeer stopped in their movements by the pipelines trampled and overgrazed lichens and other vegetation (skrobov 1984). attempts to provide crossings with ramps or underpasses met with only limited success. eventually, through the construction of lead fences in conjunction with large lakes and other natural terrain features, the wild reindeer were deflected in their fall migration away from the pipelines and into new wintering areas, primarily in the putorana mountains. there, lichen ranges existed that had been abandoned years earlier as grazing lands of domestic reindeer when the soviet government adopted a policy of collectivization of reindeer herding (syroechkovs kii 1995). subsequently, areas west of the pipelines and the yenisey river that had previously been important wintering areas for a portion of the taimyr herd were largely abandoned. heavy fallout of atmospheric pollutants in the downwind pollution plume from the metalurgical complex has occurred since development of the project (klein & vlasova 1992). the pollutants include sulfur dioxide, nitrogen oxides and heavy metals; sulfur dioxide and nitrogen oxides are primary components of acid precipitation. the prevailing downwind pollution plume extends more than 200 km to the south and south-east, and the total affected area of more than 600 000 ha had been of primary importance for winter grazing by both wild and domestic reindeer. the heavy fallout of pollutants in this area has resulted in widespread death of lichens or decrease in their growth rates, as well as of many of the vascular plants, thereby causing a major reduction in the ability of the area to support reindeer. effects on vegetation and other ecosystem components of the heavy metals present in the fallout from the norilsk atmospheric pollution are not known. the norilsk project, because of its magnitude, remoteness and location at 69"n, was a truly pioneering engineering effort at a time when the rest of the world had not yet viewed such projects as feasible in the arctic. experience from this project, developed at a time in the young soviet union when government policy almost exclusively focused on resource extraction for expansion of the nation's industrial complex, demonstrates the consequences of undertaking large-scale develop ment projects in the north without first assessing their impact on existing living resources. the problems experienced with both wild and domestic reindeer in the development and operation of the norilsk metalurgical complex where unantici pated. they demonstrated the complexity of arctic grazing systems in which freedom of movement of wild and domestic reindeer and caribou is essential for their access to, and use of, seasonal range components. they also demonstrated the sensitiv ity of lichens and other vegetation, so important as forage for reindeer and caribou, to damage, destruction and contamination from industrial pollution. in retrospect, it is obvious that if an understanding of the ecology of the wild reindeer existed at the time, pipeline routing, design and construction could have been altered to greatly reduce the subsequent impact on the reindeer. similarly, if the seriousness of the pollution effects on lichens and other forage plants was understood at the time, an assessment of the potential loss of extensive areas of grazing lands, with the asso ciated impact on the reindeer, herders and other reindeer users, could have been weighed against benefits of the project, perhaps justifying design changes and mitigation efforts. alaska's red dog mine in northwestern alaska a large leadhinc deposit has been developed in the past decade, employing more than 450 workers, many of whom are inupiat people resident in that region. the mine complex is in the mountains some 60 km from the coast of the chukchi sea. to get the processed ore to the sea where it could be stockpiled for transport south by 94 arctic grazing systems and industrial development: can we minimize conflicts? ship during the ice-free summer, a road has been constructed. the road transects the route of migration of a portion of the western arctic caribou herd during their twice annual movements to and from wintering areas to the south and calving and summering areas to the north. to prevent or minimize the possibility of obstructing the move ments of these caribou, the northwest alaska regional native corporation (nana), who own the mineral rights, in conjunction with biologists of the alaska department of fish and game, have worked closely with the mining company. by prior agreement, when notified of groups of caribou approaching the road, the mining company restricts ore trucks and other traffic until the caribou have crossed. state biologists monitor the movements of the caribou and often can anticipate timing of the approach of caribou to the road. however, it is the inupiat workers, with strong traditional apprecia tion for the caribou, who play the primary role in notifying the mining company of approaching caribou and the need to curtail road traffic (j. dau, pers. comm.). this apparently successful effort in minimizing impact on caribou of this large mining development resulted from close coopera tion between the regional native corporation, the mining company and state and federal agencies. prior to approval of development of the project, a comprehensive assessment of possible environ mental impacts was required, and plans were incorporated in the project design to minimize impacts to acceptable levels. in this case, residents in the region of the proposed development who would be most directly affected by it played a major role in determining levels of acceptability of project impacts, and development of efforts to minimize them. the policy worked out with the mining company, assuring that a high proportion of the 500000 animals, overlaps the area of potential diamond mining interest. the bathurst herd is an important subsistence resource to both dene and inuit peoples of the region who hunt them primarily in early fall as well as throughout the winter. also, in the past a limited harvest quota of caribou for commercial sale has been allocated by the government of the northwest territories to indigenous residents. development of the diamond mines will require expansion of the limited road system previously developed primarily to access a few gold mines in the area. some of the proposed new roads would cross caribou migration routes, portions of calving grounds, and summer and winter foraging areas. these roads would improve access to the caribou for subsistence hunting which now often requires long journeys by snowmobile to reach the animals in winter; however, the roads would also facilitate caribou poaching. traffic on the roads however, may delay, disrupt or deflect movements of the caribou or cause abandonment of foraging areas close to the roads: dust blowing from the roads in open terrain can significantly impact adjacent plant communities (forbes 1995; auerbach et al. 1997). proposed hydroelectric development to provide energy for mining would create impound ments, powerlines and additional roads. although the canadian government has committed itself to the concept of sustainable development in the canadian north, the rapid pace of diamond mining development has not allowed for completion of comprehensive environmental assessment, desig nation of critical caribou habitat units requiring protection, and establishment of adequate guide lines for the mining industry to assure minimiza tion of its impact on the environment. workers were hired locally, has been a major factor accounting for the relative success of the project in hydroelectric development avoiding impacts on caribou and their habitat. large-scale hydroelectric plants are uncommon in the arctic. among the exceptions are northern quebec and labrador, where provincial govern ment policy has been to harness large amounts of diamond mining in the canadian barren-grounds the discovery in this decade of major deposits of diamond-bearing rocks in the canadian arctic led to a rush by mining interests to establish numerous large-scale mines. the area of interest lies within the central barren lands, a vast region including northern fringes of the boreal forest and expanses of tundra extending hundreds of kilometres to the arctic ocean. much of the range lands occupied by the bathurst caribou herd, estimated at nearly the potential hydroelectrical energy for export to the eastern united states, adjacent ontario, and to support large-scale iron mining in the region. large impoundments have flooded extensive areas, resulting in some loss of winter range of the large george river caribou herd and several smaller herds, and possible deflection of caribou from traditional migratory routes. in one instance of rapid release of large volumes of water from an klein 2000: polar research 19(1), 91-98 95 impoundment into the caniapiscau river, over 10000 caribou of the george river herd were drowned at a traditional river crossing during the 1984 fall migration (berkes 1988). an intensive effort by the quebec government and local people was required to remove the decomposing carcasses of the drowned caribou from the river and its banks to prevent contamination of the river, which is the source of drinking water and fish used by the indigenous cree people living further down river. at that time, the george river caribou herd was estimated at 600 000 and the loss of 10 000 from the herd and the relatively small proportion of winter range flooded by the impoundments appeared to have no significant effect on the continuing abundance of caribou. roads built during construction of the impoundments were also intended to facilitate access by the cree hunters to the caribou, however, much of the road system soon became unusable because of their lack of maintenance. fish in the impoundments, which had greatly expanded existing lake systems, were found to contain dangerously high levels of mercury. the mercury, present naturally in the rocky ground that was flooded, had leached into the reservoir waters and became incorporated into the aquatic life where it moved up the food chain, becoming concentrated in the fish. the fish had been of seasonal importance to the cree people in the region; however, because of the high mercury levels in the fish which posed a health hazard if consumed, fishing in the reservoirs was discontinued. several large hydroelectric developments in northern norway have resulted in loss of grazing area for domestic reindeer (skogland & malmen 1980; reimers 1984). the impoundments have flooded grazing lands and in some cases have obstructed traditional movement routes of the reindeer. in a similar way, power transmission lines and pipelines associated with hydroelectric projects have required increased effort by the herders in moving the reindeer until the animals have adapted to these new features in the land scape. in a review of studies and experience with high voltage electric transmission lines and their effect on wild reindeer and other ungulates, reimers et al. (1997) have concluded that follow-up studies have been inadequate to assess the possible effect of the lines on wild ungulates. they suggested specific research needed to address this question (see also reimers et al. 2000, this volume). other types of development other development activities that have encroached on, or are impacting, northern grazing systems include intensive forestry and tourism. the former has been most prevalent in northern fennoscandia where impacts on domestic reindeer grazing systems have included damage to lichen forage through logging activities and scarification of soils following logging to facilitate regeneration of conifers (helle & saastamoinen 1979). (foresters, for their part, complain that young trees may be damaged by the reindeer [skuncke 19691 and by the herders’ snowmobiles.) in finland, extensive areas of mires have been drained to convert them to forest production, thus reducing availability of these important summer grazing areas for both domestic and wild reindeer (helle 1980). tourism, while offering the potential for economic benefits to reindeer herding and caribou hunting peoples, can also bring negative impacts to northern grazing systems (skogland 1994). these impacts may include: disturbance by recreational skiers and hikers during calving and displacement of animals from grazing near heavily travelled trails; competition with resident subsistence hun ters for caribou and wild reindeer by nonresident sport hunters; and construction of tourist facilities in or adjacent to critical reindeer and caribou habitats. much greater effort should be directed by the responsible governments toward assessing the impacts at high latitudes of forest practices and tourism on reindeer and caribou grazing systems. since both the vegetation and the reindeer and caribou may be slow to respond to the effects of these industrial activities, studies of their effects should be initiated as soon as possible so that results are available before extensive expansion of these industries occurs in the north. general conclusions on minimizing impacts on reindeedcaribou grazing systems 1) although reindeer and caribou throughout their circumpolar distribution are a common species, no two populations of reindeedcaribou or their habitat relationships are identical. in fact, the species rangifer tarandus is the most complex ecologi cally and evolutionarily among the deer family, 96 arctic grazing systems and industrial development: can we minimize conflicts? and it shows wide adaptive variability to its environment throughout its circumpolar distribu tion. therefore, although similarities exist be tween reindeerlcaribou grazing systems that may help in assessing possible impacts of development and planning for their minimization, each grazing system must be considered unique when threa tened by a proposed development project. collec tion of detailed information about specific grazing systems is, therefore, essential before an adequate assessment of impacts on them of proposed development projects can be made and provision made for their minimization. 2 ) background data on grazing systems is essential in planning for minimizing impacts of proposed development projects. this should include the history of population numbers of reindeer or caribou and their variation, changes that may have occurred in range use patterns or the vegetation, as well as the numbers of people dependent upon the reindeer and caribou for their livelihood, and their geographic distribution and degree of cultural and economic dependence on the animals. much of this information is available in the traditional knowledge of the people who are dependent on the reindeer and caribou. indigenous knowledge should be documented and analysed as a first step in assessing the extent of additional investigations needed to adequately understand the possible impacts of proposed development activ ities. 3 ) these environmental and sociological studies require extended periods of time for their comple tion. responsible government agencies must allow sufficient time for completion of these studies prior to any decisions on project authorization. political pressure generated by industry and business interests should not be allowed to constrain the time necessary for completion of the necessary environmental and sociological studies. 4) the relative importance of reindeer and caribou grazing systems to the people dependent upon them, economically, socially and culturally, is seldom adequately considered in the evaluation of impacts of proposed development projects and in planning for their minimization. it is therefore essential that the human role in northern grazing systems that may be affected by development projects be adequately assessed and documented, and that this information be of primary considera tion in project assessment, approval and planning for impact minimization. 5) while each proposed development project should be assessed on the basis of its individual effect on the environment and the local people, it should also be assessed in relation to the cumulative effects when considered in association with other projects in the area, both existing and planned. this has often not been done. 6) the types of industrial development occur ring in the north, be it oil and gas, mining, hydroelectric power generation, wood production or tourism, all vary in the types of impacts they may impose on northern grazing systems. there fore, minimization of their impacts may require quite different approaches unique to the specific industry. 7) contaminants resulting from industrial activ ities are of major concern to northern residents because they are slow to break down at low temperatures and they readily enter the food chains of northern ecosystems where they accumulate at higher trophic levels. because northern residents are dependent upon the reindeerlcaribou and other mammals and fish that may have accumulated these contaminants, their own health is at risk when contaminants enter northem ecosystems. adequate handling and treatment of contaminants to assure their containment must be a major consideration in assessing and planning for devel opment projects where contaminants are involved. 8) global climate change, whether from human contribution to atmospheric carbon dioxide and other “greenhouse gases” or natural causes, appears to be most pronounced in portions of the arctic. the pronounced warming trend in the north-western canadian arctic, northern alaska and much of the eurasian arctic will complicate assessment of long-term effects of proposed development projects. it is therefore important that pilot investigations be undertaken to record the changes that may be occurring in arctic vegetation and other ecosystem components as a consequence of global climate change. this information will be essential in differentiating between landscape level changes in northern ecosystems brought about by global climate change versus those that may be the result of local industry or heavy grazing pressure by semi domestic reindeer (evans 1996) or their wild counterparts (manseau et al. 1996). we can conclude that it is possible to minimize conflicts between industrial development and arctic grazing systems by using the experience gained from past development projects to avoid klein 2000: polar research 19(1), 91-98 91 the mistakes of the past and to benefit from the successes. each grazing system that may be affected by a proposed development project should be considered unique. therefore, sufficient knowl edge of the dynamics and biological functioning of the system must be obtained, using local knowl edge sources and directed research, prior to making an assessment of the impacts of the project and designing the development to minimize impacts. references auerbach, n. a,, walker, m. d. &walker, d. a. 1997: effects of roadside disturbance on substrate and vegetation properties in arctic tundra. ecol. appl. 7 , 218-235. berkes, f. 1988: the intrinsic difficulty of predicting impacts: lessons from the james bay hydro project. environ. impact assess. rev. 8 , 201-220. cameron, r. d., lenart, e. a., reed, d. j., whitten, k. n. & smith, w. t. 1995: abundance and movements of caribou in the oilfield complex near prudhoe, alaska. rangifer 15, 3-7. evans, r. 1996: some impacts of overgrazing by reindeer in finnmark, norway. rangifer 16, 3-1 9. forbes, b. c . 1995: tundra disturbance studies. 111. short-term effects of aeolian sand and dust, yamal region, northwest siberia, russia. environ. conserv. 22, 335-344. forbes, b. c. 1997: anthropogenic tundra disturbance in canada and russia. in r. m. m. crawford (ed.) disturbance and recovery in arctic lands. pp. 365-379. dordrecht: kluwer academic publ. garner, g. w. & reynolds, p. e. (eds.) 1983: updute report, 1982. buseline study of the jish, wildlife, and their habitats. anchorage: us fish and wildlife service. gamer, g. w. & reynolds, p. e. (eds.) 1984: update report, 1983. baseline study of the fish, wildlife, and their habitats. anchorage: us fish and wildlife service. helle. t. 1980: sex segregation during calving and summer period in wild forest reindeer (rangifer tarandus fennicus lonn.) in eastern finland with special reference to habitat requirements and dietary preferences. in e. reimers et al. (eds.): proceedings of the 2nd reindeedcaribou symposium, rbros, n o w a y , 1979. pp. 508-518. trondheim: direktorat for vilt og ferskvannsfisk (directorate of game and fresh water fish). helle, t. & saastamoinen, 0. 1979: the winter use of food resources of semi-domestic reindeer in northern finland. commun. inst. for. fenn. 95, 1-27. klein, d. r. & vlasova, t. j. 1992: lichens, a unique forage resource threatened by air pollution. rangifer 12, 2 1-27. kruse. j. 1999: an approach to planning research. paper presented at the international workshop, the human role in reindeer/caribou systems. rovaniemi, 10-14 february 1999. manseau, m. j., huot. j . & crete, m. 1996: effects of summer grazing by caribou on composition and productivity of vegetation: community and landscape level. j . ecol. 84,503 514. reimers, e. 1984: virkninger av menneskelig aktivitet pb rein og caribou. en lieraturstudie. (effects of human activity on reindeer and caribou. a literature study.) vn rupp. 9. natur og landskapsavdelingen, norges vassdragsog energidir ektorat (nve) (nature and env. dept., norwegian water resources and energy directorate). reimers, e., boving, p. s., coleman, j . e. & enger, p. s . 1997: study proposal for determining effects of high voltage transmission line on behavioral ecology of wild reindeer. biological institute, university of oslo. reimers, e., flydahl, k. & stenseth, r. 2000: high voltage transmission lines and their effect on reindeer: a research programme in progress. pol. res. 19(1), 75-82. russell, d. e., martell, a. m . & nixon, w. a. c. 1993: range ecology of the porcupine caribou herd in canada. rungijer, spec. issue 8. skogland, t. 1994: villrein f r a urinnvzner ti1 miljbbarometer. (wild reindeer ,from indigenous species to environmental indicator.) oslo: teknologisk forlag. skogland, t. & m d m e n , 0. 1 9 8 0 prehistoric and present habitat distribution of wild mountain reindeer at dovrefjell. in e. reimers et al. (eds.): proceedings of the 2nd international reindeer/caribou symposium, rbros. norway, 1979. pp. 130-141. trondheim: direktorat for vilt og ferskvannsfisk (directorate of game and freshwater fish). skrobov, v. d. 1984: human intervention and wild reindeer. in e. e. syroechkovskii (ed.): wild reindeer of the soviet union. pp. 90-94. new delhi: amerindian press. skuncke, f. 1969: reindeer ecology and management in sweden. biol. pup. univ. alaska 8, 1-81. syroechkovskii, e. e. 1995: wild reindeer. new delhi: oxonian press. us fish and wildlife service 1982: arctic national wildlife refuge coastal pluin resource assessment initial report, baseline .study offish, wildlife, and their habitats. anchorage: us fish and wildlife service. vlasova, t . j . , kovalev, b. i. & filipchuck, a. n. 1991: effects of point source atmospheric pollution on boreal forest vegetation of northwestern siberia. in g. weller et al. (eds.): proceedings, international conference on the role of polar regions in global change, fairbanks, alaska, 1990. pp. 423-428. fairbanks: university of alaska. 98 arctic grazing systems and industrial d e v e l o p m e n t : can we minimize conflicts? microbial communities from the sea ice and adjacent water column at the time of ice melting in the northwestern part of the weddell sea sylvie mathot, sylvie becquevort and christiane lancelot mathot, s.. becquevort. s . & lancelot. c. 1991: microbial communities from the sea ice and adjaccnt water column at the time of ice melting in the northwestern part of the weddcll sea. pp. 267-275 in sakshaug. e., hopkins. c. c . e. & 0ritsland. n . a. (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, 12-16 may 1990. polar research l o ( 1 ) . microbial composition including microalgae, bacteria and protozoans and potential metabolic activity of its autotrophic compartment were measured in december 1988 in several micro-environments that characterise the north-west sector of the marginal area of the weddell sea; infiltration and band assemblages of ice floes and adjacent waters were investigated. at the time of ice melting, a shift from a diatom dominated population (ice) to a flagellate dominated population (water column) was observed. nevertheless. this shift was not due to an “inability” of the icc-diatoms to grow in the water colum. macro grazing and/or sedimentation arc suggcstcd as possible causes of the disappearance of diatoms during ice melting. the rcmaining small autotrophic forms released by the ice would constitute a significant seeding stock for the growth of ice-edge blooms. syluie mathor, syluie becqueuortand christiane lancelot, groupe de microbiologie des milieux aquariques, university of brussels. cp 221, campus de la plaine. b-1050 brussels, belgium. introduction the annual sea ice of the southern ocean pro vides suitable microhabitats for microalgae (whi taker 1977; ackley et al. 1979; palmisano & sullivan 1983; horner 1985; garrison et al. 1986; garrison & buck 1989b), heterotrophic flag ellates and other protozoans (garrison & buck 1989a; 1989b; buck et al. 1990; garrison & gowing 1992), as well as bacteria (sullivan 1985; kottmeier & sullivan 1987; kottmeier et al. 1987). indeed the sea ice offers a set of physico chemical conditions for microorganisms living in close association with it, either attached to ice crystals or suspended in the interstitial water between ice crystals (horner 1985). when released from the ice upon melting, the fate of ice-associated algae may be variable: part of the algae settles down (schnack et al. 1985; von bodungen et al. 1986), part is grazed by pelagic herbivores such as krill (marschall 1988) or copepods (fransz 1988), and part survives in the water column (garrison & buck 1985). the latter part should constitute an inoculum for ice edge blooms that grow in the shallow, stable water column induced by the melting of pack ice (garrison et al. 1986, 1987; fryxell & kendrick 1988; smith & nelson 1985, 1986; sullivan et al. 1988). accordingly, many of the nanoand microheterotrophic species are common to both ice and water (garrison & gowing 1992), and those which seem to grow in ice after their initial incorporation (garrison & buck 1989b) may pro duce an inoculum in the water column at the time of ice melting (garrison & gowing 1992). this study presents data concerning the struc ture of microbial communities originating from sea ice biota at the time of ice melting during the period of retreat of the ice edge. we have compared microbial inhabitants (microalgae, bac teria and protozoans) of several ice environments and adjacent water columns in the weddell sector of the antarctic ocean. the possible genesis of an ice edge bloom through the release of living cells seeded into the water column depends not only on the physical properties of the adjacent water column, but also on the ability of the released ice-algae to be metabolically active. thus, the potential activity of the primary producers released by the melting process also has been tested in a simulated seeding experiment under controlled conditions in filtered seawater. 268 s . mathot, s . becqueuort & c. lancelot 5 0' 47 4 4* 56' '\ 60 ey 1' e 6 2 ' -58' t b on c u 1 5 0 a s s e y b l a g e c material and methods sampling samples were collected during the european expedition epos leg 2 on board r/v polarstern from 22 november, 1988, to 9 january, 1989. three sites were investigated in december 1988 in the marginal ice zone of the northwestern wed dell sea in an area extending from 47" to 49" w, between 61" and 62"s (fig. 1a and b). referring to the terminology proposed by hor ner et al. (1988), results presented here only concern the infiltration assemblage located at the snow-ice interface of floes (stations 169 and 194), and the band assemblage which appeared as a brown coloured band in the middle (60 t o 80 cm from the top of the ice floe) of cores taken at station 178 (fig. 1c). bottom assemblages were inconspicuous in the study area. to reduce osmotic shock (garrison & buck 1986), ice samples were melted in sterile, filtered seawater in the dark prior to fixative addition or experiment start. ice assemblages were sampled randomly. for comparison between ice and water environ ments, samples of seawater were also collected directly under the ice floes. microscopical analysis qualitative and quantitative analysis of plankton was carried out using two different microscopical methods: 1) microplankton samples (mainly dia toms, ciliates, dinoflagellates), preserved with modified lugol's solution (thomas pers. comm.), were analysed in settling chambers using the inverted microscope technique of utermohl (1958); 2) nanoplankton (mainly autotrophic and heterotrophic flagellates) and bacterioplankton samples fixed respectively with glutardialdehyde (0.5% final conc.) and formalin (2% final conc.) were analysed by epifluorescence microscopy after 4'6 diamidino-2-phenylindole (dapi) stain ing according to the procedure of porter & feig (1980). in both methods, cell volumes were calculated from measurements of the dimensions and shapes f i g . i . sampling area and sites: a . location of the sampling area in the southern ocean: b . cruise track of nov. 1988 jan. 1989 epos leg 2 expedition in the scotia/weddell sea area. showing the ice stations sampled; c. schematic repre sentation of the sea ice biota sampled. with a vertical scale (in cm) of the thickness of ice floes. microbial communities in the northwestern part of the weddell sea 269 0 0 4 of cells. in the case of diatoms, cell volumes were converted to carbon biomass according to edler’s (1979) recommendations using a conversion fac tor of 0.11 pgc pw3. for ciliates, cell volumes were converted to carbon values using the con version factor of 0.08 pgc pm-’ (sherr & sherr 1984). the conversion factor of 0.11 pgc pm-3 (edler 1979) was used for autotrophic and het erotrophic flagellates. concerning the bacteria, biovolumes were estimated on the enlargements of microphotographs. conversion into carbon biomass was done using the biovolume dependent c/biovolume ratio proposed by simon & azam ( 1989). activity measurements the experimental determination of photosyn thetic parameters involved short-term i4c incu bation (steemann-nielsen standard method) performed at different light intensities (p-i curves). bottles (cel-cult) tissue culture flasks of 60, 250 and 700ml were incubated in a water bath with running seawater at in situ temperature illuminated by artificial light. maximum irradiance reached 135 pmol m-*s-i, i.e. very close to the light saturation constant characteristic of antarctic phytoplankton. 14c incubations were conducted at in situ temperature for different fractions of light intensity (0, 1, 4, 6, 15, 20, 40, 60, 100%). incubation times of 4-6 hours were chosen after a preliminary study of p-i curves for different incubation times. this choice minimises losses by respiration and increases accuracy. after incubation, samples were filtered on gf/f filters. radioactivity was measured on the filter (photosynthetic carbon fixation) and in the dis solved organic matter (excretion). however, radioactivity of the latter was never significantly different from that of the background. excretion was therefore assumed to represent a maximum of 5% of total photosynthesis. photosynthetic parameters k,,,, a, and p were then statistically estimated by means of the platt et al. equation (1980). 2a) and band (fig. 3a) algal assemblages as well as their respective water column phytoplanktonic assemblages (figs. 2b and 3b). carbon uptake has been normalised t o “active” carbon biomass calculated from cell counts and biovolume measurements. thus, only carbon associated with vegetative, healthy autotrophic cells has been taken into account; this was a necessary correction since resting spores accounted for nearly half (45%) of the total autotrophic carbon in the band assemblage. photosynthetic characteristics of the populations as computed by statistical fitting of experimental data using the platt et al. equation (1980) are presented in table 1. from exam ination of the p-i curves, it is obvious that, apart from the band assemblages (fig. 3a), which revealed a low maximum specific rate of photo synthesis (see table 1, mean k, = 0.012 h-l), the infiltration assemblages exhibited similar values (fig. 2a, table 1, mean k, = 0.049 h-i) to those 0 0 5 0 0 4 0 0 3 0 0 2 0 01 0 infiltration assemblage k , t i ’ ,r i 0 200 400 600 moo 1000 a 1, pno1.m-0,s-1 0 0 3 0.02 0 01 u results primary producers and potential activities figs. 2 and 3 show algal uptake of carbon as a function of irradiance for typical infiltration (fig. 0 200 400 800 boo 1000 b i , pno1.m-0,s-1 fig. 2. photosynthesioirradiance relationship of natural popu lations sampled (a) in the infiltration assemblage and (b) in the adjacent water column. 270 s. mathot, s. becquevort & c . lancelot hand assemblage ~ 1 ~~i < * ''.i (veprl.l,ra cells) o o 5 i 0 0 4 0 03 0 0 2 0 200 400 6w boo woo a i , p ~ i i d . m ~ . s ' water column k. h-i 0 0 5 0 04 n 03 00' 0 0 1 0 0 203 4 0 0 ow boo ::?i> b i , pno1.m-2.6" fig. 3. photosynthesis-irradlance relalionship of natural popu lations sampled (a) in the band assemblage and (b) in the adjacent water column. for the band assemblage, only veg etative cells have been considered. of the water column phytoplankton (fig. 2b and 3b, table 1, mean k, = 0.041 h-l). photo synthetic efficiencies were in the same order of magnitude for infiltration and water column assemblages, ranging between 0.00066 h-' (prnolm-*s-')-' for the former and 0.00047 h-l(pmol m-' s-')-' for the latter. ik (index of photoadaptation) values were higher for infiltration and water column assemblages than for the band assemblages, being 75 and 92 p o l m-* s-' for the former, and much lower for the latter (table 1). thus photosynthesis irradiance relationships did not exhibit clear vari ations between infiltration assemblage and the surrounding water column, and both communities were similarly well adapted to prevailing physico chemical conditions. "taxonomic" composition the dominant autotrophic taxons present in the different environments, i.e. ice assemblages and the adjacent water column, are summarised in table 2a. results are expressed as percentages of total autotrophic cell number. this table reveals a predominantly algal community with pennate diatoms always dominant in the ice assemblages (mean = 74% for infiltration assemblage; mean = 82% for band assemblage). the diatoms were mainly of the genus nitzschia (up to 94% of autotroph cell number, e.g. n . closterium, n . cyl indrus, n. curta, n . kerguelensis), but also genera such as tropidoneis and amphiprora, which pre sented a certain variability within each type of ice assemblage as well as in between the two types studied, were present (table 2a). centric diatoms were scarce if at all present in the infiltration assemblages, whereas they accounted for 1.4 and 32% of autotroph cell num bers in the band assemblages, both as vegetative cells and resting spores. autotrophic flagellates were not abundant in the ice assemblages, and even if they did reach 51% of the autotrophic cell number (table 2a) in a particular infiltration sample, their con tuble 1. photosynthetic characteristics of the infiltration assemblage and the band assemblage (= vegetative cells only, with exclusion of the resting spores) from ice communities and of phytoplankton from the water column. n a kit ik infiltr.ass. band ass. phytoplankton 2 2 h o.ooo66 2 o.oooo7 o.ooo18 f o.oooo7 0.00042 2 0.00016 0.049 it 0.003 0.012 -c 0.007 0.041 it 0.014 75 it 12.8 62 t 15.7 92 -t 19 n ' number of samples a . photosynthetic efficiency [ h ' ( p m o l m * s ' ) . ' ] . k, : maximal specific rate of photosynthesis ( h ' ) . ik : light adaptation parameter (k,,,,' a: pmol m e ' s ' ) microbial communities in the northwestern part of the weddell sea 271 table 2. a. composition of the autotrophic community encountered in the different environments sampled. results expressed as percentage of total autotrophic cell number. (-) = negligible. infilt .assemblage band assemblage n = 4 n = 2 taxon range, x range, x water column n = 3 range, x pennate diatoms nitzschia sp. 4 1-94 70.7 2 15 57-82 70 ? 12.5 %i3 10.3% 1.8 tropidoneir sp. 0-7 2.5 2 2.5 1 . 6 2 1.8 f 0.2 (-) amphiprora sp. 0-1 0.3 2 0.4 6.5-15 10.8 2 4.3 (-) centric diatoms (-1 1.4-32 16.7 2 15.3 (-) flagellates dinoflagellates 0-2 1.0 2 1.0 s2.5 1.3 2 1.3 2-3 2.7 2 0.4 nanoflagellates &5 1 25 2 13 (-) 85-89 87.3 4 1.6 tribution to the autotrophic total biomass (table 3a) remained negligible compared to that of dia toms. thus, the autotrophic composition of the ice assemblages was highly variable and showed a patchy distribution of microalgae, reflecting the heterogeneity of the ice environment. in contrast, the composition of autotrophic communities of the adjacent water column was constant and homogeneous, without any con spicuous differences between the different locali ties. indeed, nitzschia sp. was the only diatom present, accounting for only 9 to 13% (mean = 10%) of the autotroph cell numbers (table 2a), whereas the bulk of the autotrophic population consisted of flagellated cells (8549% autotrophic nanoflagellates including cryptomonas spp., pyr amimonas spp., phaeocystis pouchetii; i-3% autotrophic dinoflagellates). in terms of biomass (table 3a), diatoms represented about one-fifth of the total autotrophic biomass (range = 19 25%, mean = 21%), and autotrophic flagellates occupied the remaining four-fifths, with a net dominance of nanoflagellates (range = 64-72%, mean = 69%) other than dinoflagellates (range = 3-18%, mean = 10%). concerning the protozooplankton abundance in the three environments considered (table 2b), there were no differences between infiltration assemblages and water column assemblages in the composition of the groups, with net dominance of heterotrophic nanoflagellates (9599% of heterotrophic cell number) over heterotrophic dinoflagellates (1-5%). the biomass of het erotrophic dinoflagellates (table 3b) was higher (mean = 31% of total heterotrophic carbon) than that of the heterotrophic nanoflagellates (mean = 20% of total heterotrophic carbon) in the infil tration assemblages, whereas in the water column, the non-dinoflagellate heterotrophic nanoflagellates dominated the flagellated fraction (see table 3b). ciliates were not significant although this group did contribute to some extent table 2. 8 . composition of the protozoan community encountered in the different environments sampled. results expressed as percentage of total protozoan cell number. 1nfilt.assemblage n = 4 taxon range, i band assemblage n = 2 range, x water column n = 3 range, x ciliates (-1 ~~ 30-80 552 25 (-) flagellates dinoflagellates 1-5 3.5 2 1.3 20-70 45 ? 25 1-4 3 4 1.3 nanoflagellates 95-99 96.5 2 1.3 (-) 9 6 9 9 97 5 1.3 272 s. mathot. s . becquevort & c. lancelot table 3. a . composition of the autotrophic biomass encountered in the various environments sampled. results expressed as percentage of total autotrophic carhon biomass. ( ) = negligihle. in611 assemblage n = l taxon rangc. x band assemblage n = 2 range. a water column n = 3 range. x diatoms 7 1 9 5 84 ? 5.6 9 1 9 9 98.5 2 0.5 1 s 2 5 21.3 2 2.4 flagellates 10.7 2 5.1 dinoflagellates 1-14 nanoflagellates s 1 4 7.5 2 4.5 0.5-1 0.8 ? 0 3 w 7 2 68.7 f 3.1 1 . 5 ? 1 . s ( ) ( ) 6.5 2 4 w.5 0.3 2 0.5 s1r phaeocystic col r cyanobacteria 0 . s 2 . 2 1 ? 0.6 ( ) ( ) tubl 3 b composition of the heterotrophic biomass encountered in the various environments sampled. results expressed as percentage of total heterotrophic biomass. lnfilt .assemblage band assemblage water column n = 4 n = 2 n = 3 taxon range. a range, x range. x protozoa ciliates 5-13 8 f. 3.6 6.2-69.3 38 f 31.6 5-10 7.2 2 2.1 dinoflagellates 10-55 31 2 19.7 0-1.3 0.1 2 0.07 9-32 19.3 2 8.3 nanoflagellates mi 20 f 10.6 ( ) 19-31 25 -c 4 bacteria 16-59 41 2 12.6 29-94 62 ? 32.2 3 m 7 48.5 f. 12.2 table 4 . composition of microorganisms in the sea ice and adjacent water column samples. results expressed in percentage of total carbon biomass (autotrophs + heterolrophs). diatoms r.s. = resting spores; diatoms v.c. = vegetative cells. ( ) = negligible. lnfilt . assem blage n = 4 taxon range. x band asscmblage n = 2 range. x water column n = 3 range, a autotrophs diatoms r.s. diatoms v.c. phaeocystis col dinoflagellates nanoflagellates cyanobacteria total heterotrophs ciliates dinoflagellates nanoflagellates bacteria ( ) 65-93 0-3.3 1-1 1 3-13 0.1-1.8 82-97 0 1-2.4 0.1-4.5 0.2-3 1 3 1 1 17 f. 8.7 1.2 ? 1.2 5.6 2 3.2 6.9 f. 4.3 0.9 2 0.6 91 -t 4.8 0.9 5 0.7 2.1 -c 1.2 1.6 2 0.7 3.8 r 3.5 12-45 50-63 0-0.3 0.2-1 ( ) ( ) 76-96 1.4-2.9 0-0. 1 m . 6 i .%22 29 ? 16.2 56.5 f. 6 0.2 f. 0.2 0.6 f 0.4 ( ) ( ) 11-15 2-10 38-50 ( ) 13.4 ? 1.6 6.7 ? 3.2 43.6 f 4 86 f 10 2 2 2 0.8 0 05 f 0 05 0 3 e 0 3 1 2 2 10.4 6@7 1 i .9-3 3 . 1 9 7-12 %27 64 ? 14.7 2.5 f 0.4 6.5 f. 1.8 9 ? 2.1 1 8 . 2 2 5.9 total 8.3 2 4.9 4-24 14 ? 10 2%40 36.3 f 4.9 microbial communities in the northwestern part of the weddell sea 273 .... ....... ........ .......... ........... ............ ............. ..... ......... ,:.::::::::::: i.i.’iiiii:iiii ........ ......... ............ diatoms >2op a infiltration assemblage b band assemblage c water column legend 1 -1 a ~ t o t r o p h s 2-10 itm autolrophs 10-20 pm autolroplis >20 pin fig. 4. composition of the total autotrophic biomass in three size classes of distribution, with distinction between diatoms and flagellates in each size range: a. infiltration assemblage 169/1; b. band assemblage 178/1; c. water column assemblage 194. to the total heterotrophic biomass (table 3b), with mean values of 8% for the infiltration assem blages, and 7% for the water column. in the band assemblages, heterotrophic nano flagellates were present in negligible numbers compared t o heterotrophic dinoflagellates and ciliates, which showed a great heterogeneity in their respective distributions (table 2b). discussion relative proportions in terms of biomass of autotrophs (diatoms, dinoflagellates, nanoflag ellates and cyanobacteria) as well as hetero trophs (ciliates, dinoflagellates, nanoflagellates, and bacteria) are shown in table 4 for both ice and water column communities. floristic analysis of the ice assemblages showed a clear dominance of diatoms over other auto trophs (65-95% of total biomass). moreover, comparison of ice assemblages indicated the pres ence of resting spores in the band assemblages, suggesting that these might be remnants from a sub-ice algal bloom from the previous year, which were “trapped” in two-year-old ice according to ackley et al. (1979) and mcconville & wetherbee (1983). in contrast, diatoms in the water column con stituted a minor fraction never exceeding 15% (table 4); the bulk of the biomass was contributed by the autotrophic flagellates (45 t o 57%) with a net dominance of the nanoflagellated fraction (78-96%). these results seem to contradict observatons made by garrison & buck (1985), garrison et al. (1986) and smith &nelson (1986), all of whom found great similarity among assem blages from ice floes and from planktonic popu lations, supporting the seeding hypothesis from the ice to the water column. our results, however, do not exclude the potential role of seeding, but do indicate that other factors (such as early graz ing by macrozooplankton) can prevent seeding of the water column assemblages. note that unlike fryxell & kendrick (1988) who suggested that phaeocystis colonies found in the water column in the same area could have been seeded from the melting ice, phaeocystis colonies were present in two of our infiltration samples where they accounted for 1 and 3% of the total biomass, but no colonies were observed in the surrounding waters. in the ice assemblages, the autotroph/ 214 s . mathot. s. becquevort & c . lancelot heterotroph biomass ratio was quite different from one sample to another, ranging between 3 and 33. in contrast, water samples presented a lower and remarkably constant ratio (1 5 2 . 5 ) . the relative proportions of heterotrophs were always more important in the water column than in the ice environment, although protozoans (including flagellates and ciliates) and bacteria are regular and abundant components of the ice biota (garrison et al. 1986). the abundance of heterotrophs in the ice environment indicates an active food web within the ice community (gar rison & buck 1989b). in fact, the relative pro portions of heterotrophs were greater in the water column since only a part of total autotrophic biomass remained in the water column at the time of ice melting. this accounts for the shift observed from a diatom dominated population (ice) t o a flagellate dominated population (water column) at the time of ice melting. however, as has been shown pre viously (table 1, fig. 2), this shift cannot be explained by an “inability” of the ice com munities at least for their autotrophic con stituentsto grow in the water column, but rather by an effective disapppearance from the water column, either by grazing pressure (macro zooplankton) or sedimentation processes. indeed, euphausiids have been shown to follow the retreating ice edge, taking advantage of the elevated food supply when the ice is melting (see sakshaug & skjoldal 1989). during the epos leg 2 expedition, cuzin-roudy & schalk (1989) reported an abundance of krill under ice floes, indicating that sea ice can provide a nursery ground for larval krill (marshall 1988) which feed on particles released by the melting infiltration and band assemblages. smetacek et al. (1990) even presents a hypothetical annual cycle where krill switch from scraping ice algae to filtering phytoplankton. the disappearance of diatoms but not of flagellates does not seem t o reflect selection of “species” but rather of particle size. as seen in fig. 4, the distribution of autotrophs in the various size ranges is inverted when going from the ice environment to the water column. this figure shows an example of autotrophic biomass distribution in three size ranges (2-10pm. 10 20 pm, > 20 pm) for an infiltration assemblage (fig. 4a), a band assemblage (fig. 4b) and a water column phytoplanktonic community (fig. 4c), with separation between diatom and flag ellate biomass contribution within each size range. although krill is capable of feeding on very small particles, large cells are taken more efficiently (segawa et al. 1983; boyd et al., 1984). meyer & el-sayed (1983) also showed the pref erential feeding on micro-sized (20-200 pm) par ticles by krill. on the other hand, because of the spatial con straint of living in the ice environment, the growth of ice algae can occur in aggregated entities in between ice crystals (tropidoneis oanheurckii often aggregated in our samples). these obser vations are in accordance with experimental results obtained by riebesell et al. (1991) col lected during the same epos expedition. being heavier, these aggregates could, together with larger cells, sink out of the surface mixed layer leaving small cells and flagellates in the adjacent water column. in fact, high sedimentation fol lowing spring blooms has been reported as being one of the fates (schnack et al. 1985) if not the dominant one (von bodungen et al. 1986) of ice edge blooms. in summary, by comparing the floristic corn position of the ice environment with that of the water column following ice melting, an obvious shift from a diatom dominated population in the ice environment to a flagellated one in the water column was observed, with an apparently neg ligible seeding effect of ice algae into the water column. when analysing the photosynthetic capa bilities of these ice algal communities (infiltration assemblages being largely dominant over band assemblages in the area of the weddell sea we visited), there is clear evidence that they could grow at the same rate as the water column assem blages. thus. other factors such as grazing by pelagic herbivores or sedimentation at very early stages during and after melting of the ice might significantly modify the structure of ice-associated microbial communities entering the water column. acknowledgernenrs. we thank r. sharek and e-m. nothig for helping in the initial identification of ice algae. v. smetacek. e . sakshaug and two anonymous reviewers provided valuable comments to the manuscript. this work is part of the belgian scientific research programme on antartica. funded by the science policy office (brussels, belgium), under contract nr antar/os. data presented here were collected during the european polorsfern study (epos) sponsored by the european science foundation and the alfred wcgcner institute for polar and marine research. bremerhaven. references ackley. s. f . . buck. k . r . & taguchi. s. 1979: standing crop microbial communities in the northwestern part of the weddell sea 275 of algae in the sea ice of the weddell sea region. deep-sea res. 26a, 269-282. boyd, c. m.. heyraud. m. & boyd, c . n. 1984: feeding of the antarctic krill euphausia superba. 1. crustacean biol. 4 . 12s141. buck, k. r., bolt. p. a. & garrison, d . l. 1990: phagotrophy and fecal pellet production by an athecate dinoflagellate in antarctic sea ice. mar. ecol. prog. ser. 60, 75-84. cuzin-roudy, j. & schalk, p. h. 1989: macrozooplankton biomass, development and activity. pp. 146-159 in hempel, i . . schalk, p. h. & smetacek, v. (eds.): the expedition antarktis v11/3 (epos leg 2) of r/v “polarstern” in 1988/ 89. reporfs on polar research. edler, l. 1979: recommendations for marine biological studies in the baltic sea phytoplankton and chlorophyll. baltic marine biologisrc 5 , 1-38. fransz, h . g . 1988: vernal abundance, structure and develop ment of epipelagic copepod populations of the eastern wed dell sea (antarctica). polar biol. 9, 107-114. fryxell, g . a . & kendrick, g . a . 1988: austral spring micro: algae across the weddell sea ice edge: spatial relationships found along a northward transect during ameriez 83. deep-sea res. 35, 1-20. garrison, d . l. & buck, k. r. 1985: sea-ice algal communities in the weddell sea: species composition in ice and plankton assemblages. pp. 103-122 in gray, j . s. & christiansen, m. e. (eds.): marine biology of polar regions and effects of stress on marine organisms. john wiley and sons. garrison, d. l. & buck, k. r. 1986: organism losses during ice melting: a serious bias in sea ice community studies. polar biol. 6 , 237-239. garrison, d. l. & buck, k. r. 1989(a): protozooplankton in the weddell sea, antartica: abundance and distribution in the ice-edge zone. polar biol. 9, 341-351. garrison, d. l. & buck, k. r. 1989(b): the biota of antarctic pack ice in the weddell sea and antarctic peninsula regions. polar biol. 10, 211-219. garrison, d. l. & gowing, m. m. 1992: protozooplankton. in friedmann. e. 1. (ed.): antarcric microbiology. in prcss. garrison, d. l.. buck. k. r. & fryxell. g . a . 1987: algal assemblages in antarctic pack ice and in ice-edge plankton. 1. phycol. 23,564-572. garrison, d. l., sullivan, c. w. & ackley, s. f. 1986: sea ice communities in antarctica. bioscience 36, 243-249. horner. r . a. 1985: ecology of sea ice microalgae. pp. 83-103 in horner, r . a. (ed.): sea ice biota. crc press, boca raton. horner. r. a , , syvertsen, e . e . , thomas, d. p. & lange. c. 1988: proposed terminology and reporting units for sea ice algal assemblages. polar biol. 8, 249-253. kottmeier, s. t., mcgrath grossi. s. & sullivan, c. w. 1987: sea ice microbial communities: 8. bacterial production in annual sea ice of mcmurdo sound, antarctica. mar. ecol. prog. ser. 35, 175-186. kottmeier. s . t. & sullivan, c. w. 1987: late winter primary production and bacterial production in sea ice and seawater west of the antarctica peninsula. mar. ecol. prog. ser. 36, marschall. h. p. 1988: the overwintering strategy of antarctic krill under the pack-ice of the weddell sea. polar biol. 9, 129-135. meyer. m. a . & el-sayed. s . z. 1983: grazing of euphausia superba dana on natural phytoplankton populations. polar biol. i , 193-203. 287-298. mcconville, m. j . & wetherbee, r. 1983: the bottom-ice microalgal community from annual ice in the inshore waters of east antarctica. 1. phycol. 19, 431. palmisano, a . c . & sullivan c . w. 1983: sea ice microbial communities (simco) 1 . distribution, abundance, and pri mary production of ice microalgae in mcmurdo sound. ant arctica in 1980. polar biol. 2, 171-177. platt, t.. gallegos, l. l. & harrison. w. g . 1980: pholo inhibition of photosynthesis in natural assemblages or marine phytoplankton. 1. mar. res. 38, 687-701. porter, k. g. & feig, y. s. 1980: the use of dapl for identifying and counting aquatic microflora. limnol. oceanogr. z s ( 5 ) . 943-948. riebesell. u . , schloss, i . , & smetacek, v. 1991: aggregation of algae released from melting sea ice: implications for seed ing and sedimentation. polar biol. i!, 239-248. sakshaug, e . & skjoldal. h. r. 1989: life at the ice edge. ambio 18(1), 60-67. schnack, s. b.,’ smetacek, v. s., von bodungen. b. & stegmann, p. 1985: utilization of phytoplankton by copepods in antarctic waters during spring. pp. 6 s 8 1 in gray, j . s. & christiansen, m. e . (eds.): marine biology of polar regions and effecfs of stress on marine organisms. john wiley and sons. segawa, s., kato, m. & murano, m. 1983: growth, moult and filtering rate of krill in laboratory conditions. mem. nod. inst. polar res., special issue 27, 9s103. sherr, b. f. & sherr, e. b. 1984: rble of heterotrophic protozoa in carbon and energy flow in aquatic ecosystems. pp. 412-423 in klug. m. j. & reddy, c . a . (eds.): currenf perspectives in microbial ecology. american society for microbiology. washington, d.c. simon. m. & aydm, f. 1989: protein content and protein synthesis rates of planktonic marine bacteria. mar. ecol. prog. ser. 51. 201-213. smetacek, v., sharek, r., & nothig e-m. 1990: seasonal and regional variation in the pelagial and its relationship to the life history cycle of krill. pp. 103-114 in kerry, k. r . and hempel. g . (eds.): antarctic ecosystems. ecological change and conseruation. springer-verlag, berlin. smith, w. 0.. jr. &nelson, d. m. 1985: phytoplankton bloom produced by a receding ice edge in the ross sea: spatial coherence with the density field. science 227, 1 6 f 1 6 6 . smith, w. o., jr. & nelson, d . m. 1986: importance of ice edge phytoplankton production in the southern ocean. biosctence sullivan, c. w. 1985: sea ice bacteria: reciprocal interactions of the organisms and their environment. pp. 159-171 in horner, r. a . (ed.): sea ice biota., c r c press, boca raton. sullivan, c. w., mcclain. c. r., comiso, j. c. & smith, w. o., jr. 1988: phytoplankton standing crops within an antarctic ice edge assessed by satellite remote sensing. j. geophys. res. 93(cio), 12487-12498. utermohl. h . 1958: zur vervollkommnung der quantitativen phytoplankton methodik. mitt. int. verein. theor. angew. limnol. 9 . 1-38. von bodungen, b.. smetacek, v. s.. tilzer, m. m. & zeitz schel, b. 1986: primary production and sedimentation during spring in the antarctic peninsula region. deep-sea res. 33, 177-194. whitaker, t . m. 1977: sea ice habitats of signy island (south orkneys) and their primarry productivity. pp. 75-83 in llano, g. a . (ed.): adaptations within antarcric ecosystems. gulf publishing. houston. 36, 251-257. no job name late pleistocene fossil find in svalbard: the oldest remains of a polar bear (ursus maritimus phipps, 1744) ever discoveredpor_087 455..462 ólafur ingólfsson1 & øystein wiig2 1 university of iceland, department of earth sciences, askja, is-101 reykjavik, iceland 2 national centre for biosystematics, natural history museum, university of oslo, p.o. box 1172 blindern, no-0318 oslo, norway abstract during recent fieldwork in svalbard, a well preserved subfossil left mandible of a polar bear (ursus maritimus phipps, 1774) was discovered. a 14c age determination shows that it is older than 45 ky (kilo-years), and an age determination with infrared-stimulated luminescence—together with the stratigraphic position of the bone—suggests that it is of eemian–early weichselian age: 130–110 ky old. this makes the find the oldest remains of a polar bear ever discovered. morphological analyses of the mandible suggest that it comes from a fully grown male that was similar in size to extant male polar bears. the comparative study of other available subfossil polar bear remains did not reveal any significant change in size of polar bears during the late quaternary. keywords late pleistocene; polar bear; prins karls forland; subfossil; svalbard; ursus maritimus. correspondence ólafur ingólfsson, university of iceland, department of earth sciences, askja, is-101 reykjavik, iceland. e-mail: oi@hi.is doi:10.1111/j.1751-8369.2008.00087.x the polar bear (ursus maritimus phipps, 1774) is the largest of the four extant bear species of the genus ursus, the other three species being the brown bear (ursus arctos l., 1758), the american black bear (ursus americanus pallas, 1780) and the asiatic black bear (ursus thibetanus cuvier, 1823) (nowak 1999; wozencraft 2005). the polar bear is closely related to the brown bear, and fertile hybrids between the species are well known from zoos (gray 1972). recently a polar bear–brown bear hybrid was shot in the wild in the canadian arctic (national geographic news 2006). based on the dental characteristics of the polar bear, thenius (1953) concluded that a relatively late descent from the brown bear was probable, and pointed out that the close relationship between polar bears and brown bears is corroborated by the two species being able to produce fertile hybrids. kurtén (1964) concluded that polar bears probably branched off from brown bears that became isolated on siberian coastal enclaves some time during the midpleistocene, 800–130 kya (kilo-years ago), and with time became increasingly specialized carnivores that hunted on the pack ice. this conclusion has been supported by genetic studies on the relationship between living brown bears on the alexander archipelago, alaska, and polar bears (heaton et al. 1996). today, polar bears have a circumpolar distribution, and the southern limit of their range is primarily determined by the distribution of pack ice and landfast annual ice during the winter (demaster & stirling 1981; amstrup 2003). the fossil record of the polar bear is very poor (kurtén 1964; harington 2008; laidre et al. 2008), and its evolutionary history is not well known. in light of the scarcity of polar bear fossils, every new find is of interest. this paper reports on the find of an eemian–early weichselian (130–110 kya) left mandible from the poolepynten coastal cliffs (78°27′n, 11°44′e), prins karls forland, svalbard (fig. 1), identified to be from a polar bear. stratigraphy of the poolepynten sections bergsten et al. (1998) and anderson et al. (1999) studied the stratigraphy, depositional history and environmental development of the poolepynten coastal cliffs (fig. 2). anderson et al. (1999) recognized a sequence of two different marine units, which they labelled units a and c. the marine units a and c are separated by a thick till complex, unit b, composed of both subglacially deposited lodgement till (unit b1) and a chaotic component of pushed, as well as slumped and reworked, glacial sediments (unit b2). the cliff section is capped by littoral gravels, unit d, separated from the underlying units by an erosional unconformity and a boulder lag. the lowermost unit a is characterized by stratified fineto-medium sand, and its marine origin is manifested in kelp horizons and in the random occurrence of subfossil molluscs. outsized pebbles and cobbles occur randomly in the unit, suggesting rafting by sea ice, glacial ice or kelp polar research 28 2008 455–462 © 2008 the authors 455 mailto:oi@hi.is during the deposition of the unit. it is interpreted as a prodelta formation, deposited from sediment gravity flows in a nearshore, shallow marine environment (fig. 2b). the subfossil mollusc fauna of unit a contains four bivalve species, which are well preserved and occur in a living position in the sediment (anderson et al. 1999). all species currently occur on svalbard. a detailed study of the foraminiferal stratigraphy by bergsten et al. (1998) shows that unit a contains an abundant and diversified foraminiferal fauna, dominated by arctic species, but also with a number of boreal and boreal– arctic species being present. bergsten et al. (1998) concluded that the foraminifera fauna of unit a is similar to modern fauna in shallow sites in svalbard, and that the fauna reflects an arctic, open-marine environment, influenced by glacier input and advection of warm north atlantic water. a 14c date on kelp yielded an infinite age of >49 ky, and a sediment sample dated by the infraredstimulated luminescence (irsl) method gave an age envelope of 80–150 ky. bergsten et al. (1998) and anderson et al. (1999) argued that unit a might be of last interglacial (eemian) to early weichselian age. the upper marine unit c constitutes the bulk of the western part of the cliffs (fig. 2a). its marine origin is confirmed by numerous (>70) kelp layers and in situ marine molluscs. it is interpreted as a prodelta formation, deposited from sediment gravity flows/turbidites in a nearshore marine environment (fig. 2b). the mollusc and foraminifera fauna indicate nearshore marine conditions similar to those of today. two 14c dates from marine kelp gave infinite ages (>41 and >49 ky), and an irsl date of the sediments provided an age envelope of 40–70 ky. the geometry of the till complex, unit b, is interpreted to define a glacier-eroded basin, where unit a has been removed from the western part of the basin, and where unit c was deposited subsequently to the deposition of unit b (fig. 2a). subunit b1, the lodgement till, is a massive matrix-supported silty/clayey diamicton, containing numerous subangular, striated and bullet-shaped stones and boulders of local provenance. a clast fabric analysis showed strong preferred clast orientation, indicating ice movement from the west. the contact with the underlying unit a is partly sharp, and partly diffuse, and has been deformed by a glacial push. a well-developed drag fold, signifying a glacial push from the west, was observed in unit a, just below the lower contact with unit b1. subunit b2 is composed of diamicton, ranging from fig. 1 (a) prins karls forland, the westernmost island in the svalbard archipelago. (b) poolepynten, in central–southern prins karls forland. (c) simplified map of surface deposits landwards of the poolepynten sections. modified from anderson et al. (1999). subfossil polar bear mandible from svalbard ó. ingólfsson & ø. wiig polar research 28 2008 455–462 © 2008 the authors456 stratified to massive, and poorly sorted sandy gravel; its lower contact with unit a is either sharp and erosive or diffuse (fig. 2a). the sediments of subunit b2 are interpreted as subaquatic redeposition of the b1 till by slumping (fig. 2b). there is no absolute age control on unit b, but it is younger than the underlying unit a and older than the overlying unit c, and consequently has a proposed age of 70–80 ky (fig. 2b). the mandible (fig. 3) was discovered at ca. 320 m in the section transect, about 3.5 m a.s.l. (fig. 2a). it was embedded in a heavily glaciotectonically deformed section of unit a, close to the drag fold below the contact with unit b. dating of the polar bear mandible the mandible was dated by accelerator mass spectrometry (ams) 14c age determination on a sample (about 50 mg) drilled out from the canine tooth at the lund university dating laboratory, sweden. it was dated to be older than 45 ky (sample lus-6155; table 1). measurements of the polar bear mandible in accordance with von den driesch (1976), the following five measurements of the mandible were taken: (1) mandible length (measured from the infradentale to the midpoint of the condyle process); (2) mandible height (measured from the basal point of the angular process to the coronion); (3) cheek tooth-row length (measured from the anterior margin of the p4 alveolus to the posterior margin of the m3 alveolus); (4) length of m3 alveolus; (5) breadth of m3 alveolus. for comparison, the same measurements were taken on 55 (25 females and 30 males) mandibles from adult fig. 2 (a) schematic presentation of the general stratigraphy in the poolepynten coastal sections. (b) composite log for the stratigraphy of the poolepynten coastal site sediments, inferred depositional environments, events and ages. modified from anderson et al. (1999). the star indicates the stratigraphic position of the polar bear mandible. fig. 3 the poolepynten polar bear mandible. (a) lateral view. (b) dorsal view. subfossil polar bear mandible from svalbardó. ingólfsson & ø. wiig polar research 28 2008 455–462 © 2008 the authors 457 (>4 years old) polar bears hunted in svalbard in 1963–64, which are now held in the collection of the natural history museum, university of oslo. identification and description of the polar bear mandible the mandible was identified to be from a polar bear according to the following characteristics. 1. m3 has two roots. in most brown bears the two roots have grown together (erdbrink 1953). 2. the mandibular condyle lies on a line drawn along the alveoli of the tooth row. in brown bears the condyle is situated above this line (nordmann & degerbøl 1930). 3. the caudal margin of the coronoid process is strongly concave. in brown bears the margin is slightly concave (stubbe 1993). overall, the mandible from poolepynten is very well preserved. the only tooth preserved is the canine, whereas the incisors, premolars, and molars are absent. the dental alveoli where the teeth are missing have sharp and distinct edges. the canine is worn at the apex, and is assumed to belong to an adult specimen. the canine enamel is somewhat fractured. the muscle ridges and foramina are largely intact. the serrated surface of the mandibular symphysis is quite distinct, although it is a little worn at the edges. overall, the mandible shows moderate signs of wear, which is consistent with some reworking before deposition. it has probably been introduced to the sediment either by slumping or ice rafting. measurements of the poolepynten mandible are given in table 2, together with measurements of the only two other known subfossil polar bear mandibles: one from asdal, denmark, as described by nordmann & degerbøl (1930), and one from finnøy, norway (measured by a.j. nærøy, archaeological museum, stavanger, norway; blystad et al. 1983). the poolepynten mandible is smaller than the two other jaws in all dimensions except the table 1 subfossil polar bear (ursus maritimus) specimens and their reported ages. fossil find, location age determination (ky) lab. no. inferred age (ky) references kolnæs, greenland 440 � 45 k-352 bennike (1991) north-eastern greenland 820 � 60 aar-1776 andreasen (1997) washington land, greenland 960 � 60 aar-5775 bennike (2002) washington land, greenland 1415 � 60 aar-5774 bennike (2002) arctic canada 1510 � 30 cams-66368 unpubl. data, art dyke, pers. comm. 2006 victoria island, nunavut, canada 1560 � 65 gif-7512 harington (2003) 1350 � 40 gif-8434 1310 � 40 gif-8178 brønlund fjord, greenland 1520 � 110 aar-1357 bennike (1997) prince of wales island, nunavut, canada 2135 � 120 beta-18129 harington (2003) sønderland, greenland 3320 � 85 k-5928 rasmussen (1996) sønderland, greenland 3470 � 85 k-5930 rasmussen (1996) nuulliit, thule, greenland 5060 � 95 k-2560 grønnow & jensen (2003) svenskøya, svalbard 7760 � 50 t-4167 unpubl. data, otto salvigsen, reported by harington (2008) kuröd, bohuslän, sweden 10.170 � 125 lu-1075 berglund et al. (1992) 10.360 � 130 lu-1074 finnøy, norway 10.925 � 110 t-4724 blystad et al. (1983); berglund et al. (1992). asdal, denmark 11.240 � 180 k-3741 aaris-sørensen & petersen (1984); berglund et al. (1992) östra karup, scania, sweden 12.230 � 130 lu-1076 berglund et al. (1992) kullaberg, scania, sweden 12.320 � 125 lu-602 berglund et al. (1992) 12.450 � 145 lu-660 12.480 � 185 lu-661 nordcemgrotta, kjæpsvik, northern norway 22 lauritzen et al. (1996); hufthammer (2001) hamnsundhelleren, western norway 36–28 middle weichselian valen et al. (1996); hufthammer (2001) nordcemgrotta, kjæpsvik, northern norway 39–42, >70 � 8.5 early weichselian lauritzen et al. (1996); hufthammer (2001) poolepynten, prins karls forland, svalbard, norway >45 (14c) 150–80 (irsl) lus-6155 eemian to early weichselian (130–110) this paper subfossil polar bear mandible from svalbard ó. ingólfsson & ø. wiig polar research 28 2008 455–462 © 2008 the authors458 length and breadth of the m3 alveoli, which are larger. the asdal jaw was assumed to be from a male, whereas the finnøy bear was certainly male, as the baculum was found with the nearly complete skeleton. these two males are not larger than present-day polar bears, according to data presented by aaris-sørensen & petersen (1984) and in table 3. the poolepynten mandible has a total length and cheek tooth-row length of a male, whereas the mandible height is in the overlap zone between males and females (figs. 4, 5). the size of the alveolus of the m3 of the poolepynten specimen falls in the range of the largest extant males (fig. 6). larsen (1971) used the length of the cheek tooth-row to sex mandibles in extant individuals from svalbard with high accuracy. all mandibles with a cheek tooth-row length of >70 mm were males. his measurement points were on the crowns of the teeth, whereas we have used the edges of the alveoli. however, these two measurements are not very different. applying the cheek toothrow length criterion of larsen (1971) to sex the present jaw, it is classified as a male (fig. 5). the determination of the ontogenetical age of the specimen by using the layering in the cementum of the canine has not been attempted. that method necessitates sectioning, and consequently the partial destruction of the find. however, by comparing the dimensions of the mandible with those of recent polar bears, as well as the level of wear of the canine, we assume that the jaw is from a fully grown specimen. discussion a compilation of all of the finds of polar bear remains of pre-holocene age (table 1) shows that these finds are rare. this can perhaps be attributed to the fact that polar bears for the most part live and die on the pack ice, making their preservation in terrestrial sediments exceptional. the true age of the poolepynten mandible is probably within the envelope of 80–150 ky, as determined by the irsl age determination for unit a. the lithostratigraphy of unit a suggests it was deposited during a period of high relative sea levels, subsequent to a regional deglaciation. the foraminifera content of unit-a sediments suggests advection of relatively warm, north atlantic water to the site at the time of deposition. these conditions on the west coast of svalbard were certainly met at the onset of the last interglacial period, the eemian, some 130 kya, and possibly at the onset of an early weichselian interstadial, some 110 kya (mangerud et al. 1998). our best age estimate for the poolepynten mandible is thus 130–110 ky. apart from the poolepynten specimen, the two other reported finds of polar bear remains presumed to be from fig. 4 the relationship between mandible length and mandible height in polar bears. table 2 measurements (mm) of the three known subfossil polar bear mandibles. measurement (mm) poolepynten, svalbard asdal, denmark finnøy, norway mandible length 234.8 283 262 mandible height 87.4 118 116 cheek tooth-row length 75.2 79.9 76 length of the m3 alveoli 17.6 16 15 breadth of the m3 alveoli 11.0 10 11 table 3 measurements (mm) of adult polar bear mandibles from svalbard, 1963–64. measurement (mm) females males n mean sd range n mean sd range mandible length 25 210.57 11.85 175.8–223.5 30 242.53 14.57 205.4–266.8 mandible height 25 85.49 6.24 68.7–96.0 30 101.87 9.66 80.7–115.3 cheek tooth-row length 25 66.04 1.81 61.5–70.3 30 74.38 2.82 66.7–79.0 length of the m3 alveolus 25 14.03 1.01 11.4–16.1 29 16.34 1.22 12.8–18.5 breadth of the m3 alveolus 25 8.76 0.75 7.1–9.9 27 9.96 0.93 7.0–11.4 subfossil polar bear mandible from svalbardó. ingólfsson & ø. wiig polar research 28 2008 455–462 © 2008 the authors 459 early weichselian deposits are from kew bridge, london, and from cave sediments at nordcemgrotta, in northern norway (table 1). the kew bridge specimen was dated on the basis of the stratigraphical position of the find: below it, stratigraphically, were sediments containing warm, interglacial forest fauna, thought to be of last interglacial (eemian) age. there are no absolute age determinations for the fossil, but it has been assumed to be around 70-ky old. the kew bridge find is special in that it is an ulna of a very large animal, considerably larger than present-day polar bears. kurtén (1964) assigned it to a polar bear subspecies, ursus maritimus tyrannus. the kew bridge specimen has recently been reinvestigated by scientists at london’s natural history museum, and they are now confident that the kew animal was a type of brown bear, u. arctos (andy currant, pers. comm. 2008). the finds from nordcemgrotta were radiocarbon dated to 39–42 ky b.p., and a 230th/234u dating of calcareous concretions in the laminated sediments above the sedimentary horizon containing the fossil polar bear bones assigned them a minimum age of 70 � 8.5 ky b.p. (lauritzen et al. 1996). opinions differ as to the timing of the polar bear branching off from the brown bear lineage. kurtén (1964, 1968) suggested, on the basis of studies of the fossil material, a late origin of polar bears, and that perhaps the species had evolved as recently as 70–100 kya. some mitochondrial dna (mtdna) studies have confirmed kurtén’s supposition of a relatively late polar bear evolution from within the range of brown bear populations. however, age models based on molecular studies of evolutionary relationships among extant species of bears differ considerably as to the divergence time of polar bears from brown bears: wayne et al. (1991) suggested that this happened 70–100 kya; talbot & shields (1996) proposed that the process began some time in the interval 200– 250 kya, or perhaps a little earlier; whereas yu et al. (2007) concluded that this might have occurred 930– 1170 kya. the age of the mandible from poolepynten is close to the youngest estimates of the origin of the species, according to kurtén (1968) and wayne et al. (1991), and shows that the polar bear was a morphologically distinct species at that time. kurtén (1968) showed that the length of the lower molars fluctuated in size in pleistocene and holocene brown bears. there was an apparent increase from the eemian interglacial through the weichselian glacial stage, and thereafter a decrease during the holocene up to the present day. the same postglacial reduction in size of brown bear molars was found by østbye et al. (unpubl. ms.). a characteristic feature in the evolution of the polar bear is a reduction in the number and size of cheek teeth (thenius 1953; kurtén 1964; vershchagin 1969). the reduction is particularly related to the size of m2 and m3. the size of the alveolus of the m3 of the poolepynten specimen falls within the range of the largest extant males (fig. 6, table 3). the other measurements also compare fig. 5 the relationship between mandible length and cheek tooth-row length in polar bears. fig. 6 the relationship between mandible length and length of the m3 alveolus in polar bears. subfossil polar bear mandible from svalbard ó. ingólfsson & ø. wiig polar research 28 2008 455–462 © 2008 the authors460 well with extant males (figs. 4, 5). the size of the two polar bear mandibles from asdal and finnøy are also comparable with extant males. berglund et al. (1992) detected no size difference between late weichselian polar bears from southern sweden and extant individuals. consequently, the present subfossil polar bear material indicates little or no change in the size of polar bears during the late quaternary. summary and conclusions the poolepynten subfossil mandible, which we argue is from a fully grown male, is probably the oldest polar bear find discovered so far. its age envelope is 150–80 ky, but its true age is interpreted to be 130–110 ky. the poolepynten mandible dimensions, combined with measurements of other fossil finds and extant males, suggests little or no changes in polar bear size during the late quaternary. acknowledgements student participants in the university centre in svalbard course ag-301, july 2004, cleaned the poolepynten sections and discovered the subfossil polar bear mandible. anne karin hufthammer at the museum of zoology, university of bergen, gave valuable suggestions regarding the fossil occurrences of polar bears. ole bennike, geological survey of denmark and greenland, copenhagen, and art dyke, geological survey of canada, are thanked for information on fossil polar bear finds in greenland and arctic canada. we thank arne j. nærøy for providing measurements of the finnøy jaw. erik w. born at the greenland institute of natural resources, nuuk, commented on the manuscript. the manuscript benefitted from constructive comments by c.r. harington, a.e. derocher and one anonymous reviewer, which is gratefully acknowledged. references aaris-sørensen k. & petersen k.s. 1984. a late weichselian find of a polar bear (ursus maritimus) from denmark and reflections on the paleoenvironment. boreas 13, 29–33. amstrup s.c. 2003. polar bear, ursus maritimus. in g.a. feldhamer et al. (ed.): wild mammals of north america: biology, management, and conservation. pp. 587–610. baltimore: john hopkins university press. anderson t., forman s.l., ingólfsson ó. & manley w. 1999. late quaternary environmental history of prins karls forland, western svalbard. boreas 28, 292–307. andreasen, c. 1997. the prehistory of the coastal areas of amdrup land and holm land adjacent to the northeast water polynya: an archaeological perspective. journal of marine systems 10, 41–46. bennike o. 1991. marine mammals in peary land, northern greenland. polar record 27, 357–359. bennike o. 1997. quaternary vertebrates from greenland: a review. quaternary science reviews 16, 899–909. bennike o. 2002. late quaternary history of washington land, north greenland. boreas 31, 260–272. berglund b.e., håkansson s. & lepiksaar j. 1992. late weichselian polar bear (ursus maritimus phipps) in southern sweden. sveriges geologiska undersökning, series ca. 81, 31–42. bergsten h., andersson t. & ingólfsson ó. 1998. foraminiferal stratigraphy of raised marine deposits representing isotope stage 5, prins karls forland, western svalbard. polar research 17, 81–91. blystad p., thomsen h., simonsen a. & lie r.w. 1983. find of a nearly complete late weichselian polar bear skeleton, ursus maritimus phipps, at finnøy, southwestern norway: a preliminary report. norsk geologisk tidskrift 63, 193–197. demaster d.p. & stirling i. 1981. ursus maritimus (polar bear). mammalian species 145, 1–7. erdbrink, d.p. 1953. a review of fossil and recent bears of the old world. devanter: drukkerij jan de lange. gray a.p. 1972. mammalian hybrids. a check-list with bibliography. 2nd edn. slough: commonwealth agricultural bureaux. grønnow b. & jensen j.f. 2003. the northernmost ruins of the globe: eigil knuth’s archaeological investigations in peary land and adjacent areas. meddelelser om grønland. man & society 29. copenhagen: danish polar center. harington c.r. 2003. annotated bibliography of quaternary vertebrates of northern north america. toronto: university of toronto press. harington c.r. 2008. the evolution of arctic marine mammals. ecological applications 18, s23–s40. heaton t.h., talbot s.l. & shields g.f. 1996. an ice age refugium for large mammals in the alexander archipelago, southeastern alaska. quaternary research 46, 189–192. hufthammer a.k. 2001. the weichselian (c. 115,000–10,000 b.p.) vertebrate fauna of norway. bollettino della societá paleontologica italiana 40, 201–208. kurtén b. 1964. the evolution of the polar bear, ursus maritimus phipps. acta zoologica fennica 108, 1–30. kurtén b. 1968. pleistocene mammals of europe. london: weidenfeld and nicolson. laidre k.l., stirling i., lowry l.f., wiig ø., heide-jørgensen m.p. & ferguson f.h. 2008. quantifying the sensitivity of arctic marine mammals to climate-induced habitat change. ecological applications 18, s97–s125. larsen t. 1971. sexual dimorphism in the molar rows of the polar bear. journal of wildlife management 35, 374–377. lauritzen s.-e., nese h., lie r.w, lauritzen å & løvlie r. 1996, interstadial/interglacial fauna from norcemgrotta, kjøpsvik, north norway. in s.e. lauritzen (ed.): climate change: the karst record. karst waters institute special subfossil polar bear mandible from svalbardó. ingólfsson & ø. wiig polar research 28 2008 455–462 © 2008 the authors 461 publication 2. pp. 89–92. charles town, wv: karst waters institute. mangerud j., dokken t., hebbeln d., heggen b., ingólfsson ó., landvik j., mejdahl v., svendsen j.i. & vorren t. 1998. fluctuations of the svalbard–barents sea ice sheet the last 150,000 years. quaternary science reviews 17, 11–42. national geographic news 2006. photo in the news. polar bear–grizzly hybrid discovered. accessed on the internet at http://news.nationalgeographic.com/news/2006/05/ bear-hybrid-photo.html on 6 march 2008. nordmann v. & degerbøl m. 1930. en fossil kæbe av isbjørn (ursus maritimus l.) fra danmark. (a fossil polar bear jaw [ursus maritimus l.] from denmark.) vitenskabelige meddelelser fra dansk naturhistorisk forening 88, 273–286. nowak r. m. 1999. walker’s mammals of the world. 6th edn. baltimore: johns hopkins press. østbye k., østbye e., lauritzen s.-e. & wiig ø. unpubl. ms. european holocene brown bear, ursus arctos l., are there indications for a post-glacial body-(teeth)-size reduction? rasmussen k.l. 1996. carbon-14 datings from northern east greenland. in b. grønnow & j. pind (eds.): the paleo-eskimo cultures of greenland. pp. 188–189. copenhagen: danish polar center. stubbe m. 1993. gattung ursus linnaeus, 1758. (the genus ursus linnaeus, 1758.) in m. stubbe & f. krapp (eds.): handbuch der säugetiere europas. band 5. raubsäuger—carnivora (fissipedia). teil i. canidae, ursidae, procyonidae, mustelidae 1. (handbook of european mammals. volume 5. carnivores—carnivora [fissipedia]. part i. canidae, ursidae, procyonidae, mustelidae 1.) pp. 252–253. wiesbaden: aula verlag. talbot s.l. & shields g.f. 1996. phylogeography of brown bears (ursus arctos) of alaska and paraphyly within the ursidae. molecular phylogenetics and evolution 5, 477–494. thenius e. 1953. concerning the analysis of the teeth of polar bears. mammalogical bulletin 1, 14–20. valen v., mangerud j., larsen e. & hufthammer a.k. 1996. sedimentology and stratigraphy in the cave hamnsundhelleren, western norway. journal of quaternary science 11, 185–201. vershchagin n.k. 1969. the origin and evolution of the polar bear. in a.g. bannikov et al. (eds.): the polar bear and its conservation in the soviet arctic. pp. 25–51. leningrad: gidrometereologizdat. (translated by department of the secretary of state translation bureau, canada, no. 5776, 1970.) von den driesch a. 1976. a guide to the measurements of animal bones from archaeological sites. peabody museum bulletin 1. cambridge, ma: peabody museum. wayne r.k., van valkenburgh b. & o’brien s.j. 1991. molecular distance and divergence time in carnivores and primates. molecular biology evolution 8, 297–319. wozencraft w.c. 2005. order carnivora. in d.e. wilson & d.a. reader (eds.): mammal species of the world. pp. 352–628. baltimore: john hopkins university press. yu l., li y.-w., ryder o.a. & zhang y. 2007. analysis of complete mitochondrial genome sequences increases phylogenetic resolution of bears (ursidae), a mammalian family that experienced rapid speciation. bmc evolutionary biology 7, 198–209. subfossil polar bear mandible from svalbard ó. ingólfsson & ø. wiig polar research 28 2008 455–462 © 2008 the authors462 http://news.nationalgeographic.com/news/2006/05 no job name antarctic cloudspor_148 150..158 tom lachlan-cope british antarctic survey, high cross, madingley road, cambridge, cambridgeshire cb3 0et, uk. e-mail: tlc@bas.ac.uk abstract sensitivity studies with global climate models show that, by their influence on the radiation balance, antarctic clouds play a major role in the climate system, both directly at high southern latitudes and indirectly globally, as the local circulation changes lead to global teleconnections. unfortunately, observations of cloud distribution in the antarctic are limited and often of low quality because of the practical difficulty in observing clouds in the harsh antarctic environment. the best surface observations suggest that the fractional cloud cover at the south pole is around 50–60% in all seasons, whereas the cloud cover rises to around 80–90% close to the coast of the continent. microphysical observations of cloud parameters are also very sparse in the antarctic. however, the few measurements that do exist show predominantly ice-crystal clouds across the interior, with mixed-phase clouds close to the coasts. crystal sizes vary from 5 to 30 mm (effective radius) in the interior to somewhat larger ice crystals and water drops near the coast. a wide range of crystal shapes is observed at all sites. this review considers the available cloud observations and highlights the importance of antarctic clouds and the need for better observations in the future. keywords antarctic; clouds; mixed phase. doi:10.1111/j.1751-8369.2010.00148.x clouds are an important part of the global climate system. for example, the fourth assessment report issued by the intergovernmental panel on climate change (ipcc) noted that the indirect effect of aerosols on clouds is a relatively large negative radiative forcing of -0.7 wm-2, but that the range of uncertainty in this value is large and the level of scientific understanding is “low” (ipcc 2007: fig. spm2). the feedbacks associated with clouds, and whether clouds act to warm or cool the atmosphere, are complex, and are not properly understood even at mid-latitudes where they have been observed in detail for many years. in the antarctic, cloud observations have largely been confined to synoptic observations, although in recent years these measurements have been supplemented by occasional in situ microphysical measurements, mainly of low cloud from the surface, and radiometric measurements made from the surface and from satellite data. these measurements have only been made at a few locations—the south pole and some coastal stations—and these locations may not be representative of the continent as a whole. the microphysical properties (shape, size, concentration and phase, i.e., whether solid or liquid) of cloud particles can have a major impact on the earth’s radiation budget, so it is important that they are correctly represented within climate models. however, the parameterizations of clouds used in global climate models have normally been developed using measurements made in mid-latitudes, and these may not be applicable to antarctic clouds. again, because of the isolated and harsh environment of the continent few in situ measurements have been of the microphysical properties of clouds in the antarctic. this review of antarctic clouds first looks at the basic measurements of cloud cover taken visually by observers and from satellite measurements. later, more detailed microphysical measurements are considered before finally discussing the impact of clouds on the radiation balance and climate of antarctica. cloud cover figure 1 shows a composite infrared satellite image of the antarctic continent and the surrounding oceans. the most noticeable features are the frontal cloud bands associated with large, mid-latitude depressions that circle the antarctic continent. the clouds associated with these frontal systems tend to be deep, and so the cloud tops are polar research 29 2010 150–158 © 2010 the author, journal compilation © 2010 blackwell publishing ltd150 mailto:tlc@bas.ac.uk high and cold, and show up as white in the infrared image. between the high frontal cloud bands large areas of uniform low stratus, or sea ice, can be seen close to and encircling the continent. it is difficult to distinguish between low cloud and sea ice in satellite imagery. however, it is likely that most of the large areas of uniform cover surrounding the continent are clouds. away from the continent the stratus tends to break down into convective cumulus cells. an interesting feature seen in the clouds in this composite are the two mesoscale cyclones (or polar lows; see rasmussen & turner 2004) around 120° and 150°e: these small cyclones are common at high latitudes, particularly where there is a large sea–air temperature difference. moving over the continent it becomes more difficult to distinguish between cloud and the underlying snow and ice surface, although in this image it appears that the high-level frontal cloud does not encroach very far onto the continent. although visual examination of satellite imagery gives us some insight into the distribution of clouds over antarctica, for most investigations it is necessary to have some objective measure of the clouds. several different objective methods have been used to measure cloud cover in the antarctic. these range from ground-based visual observations to space-borne passive instruments, such as those used to obtain fig. 1, and active measurements such as light detection and ranging (lidar). these methods can give quite different results, and it can be difficult to establish the true value of the extent and frequency of cloud. surface visual observations have been routinely made at antarctic research stations for the last 50 years, and give the longest running cloud data set available (hahn & warren 2003). however, the surface observing sites are widely spaced in antarctica, and most are located close to the coast. there have been many changes to the surface observational record, as sites have changed location, and there have been modifications to the observing practice. visual observations are, by their very nature, subjective, and changes in observer can result in step changes in particular measurements. this can decrease their value when looking for long-term trends. also, visual observations during the night are difficult to make because of the low level of illumination of the clouds (hahn et al. 1995), and this is particularly true of antarctic clouds during the winter. figure 2 shows the annual cycle of fractional cloud cover at the south pole from visual observations. fig. 1 infrared antarctic cloud composite image for 29 september 2008. (image provided by, and used with permission of, the antarctic meteorological research center, university of wisconsin–madison.) antarctic cloudst. lachlan-cope polar research 29 2010 150–158 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 151 this indicates a decrease in cloud cover during the winter, when the clouds are difficult to observe, compared with the summer months. surface radiation measurements can also be used to derive cloud cover. town et al. (2007) compared fractional cloud cover from visual observations, satellite retrievals and surface-based infrared measurements at the south pole. they suggested that the best measurements are those retrieved from surface-based pyrgeometer measurements, both in terms of accuracy and length of record, as they are not affected by the lack of sunlight. town et al. (2007: fig. 6) compared surface visual observations with values retrieved from the pyrgeometer, and showed that during summer the two values agree well, whereas during winter the visual observations are around 20% lower. the pyrgeometer values suggest that the cloud cover at the south pole is constant throughout the year, at around 50–60%. surface measurements are limited spatially, especially in data-sparse regions such as antarctica. passive satellite instruments measure the upwelling radiation emitted from the surface or atmosphere, and measurements taken using such instruments have a much better spatial coverage. with passive measurements it can be difficult to distinguish between the clouds and the underlying snow surface, as the temperature and radiative properties of the cloud and snow surface are similar. however, there have been several attempts to retrieve cloud cover from the us national oceanic and atmospheric administration (noaa) series of polar orbiting satellites that measure in the visual and infrared bands, most notably the international satellite cloud climatology project (isccp) (see rossow & schiffer 1999; hatzianastassiou et al. 2001). these cloud retrievals are compared with surface observations in fig. 2, where it can be seen that the satellite clouds levels are less than the surface observations during the summer, but are more during the winter. another set of retrievals using noaa satellite data are the extended advanced very high resolution radiometer (avhrr) polar pathfinder (app-x) data set (see town et al. 2007; wang & key 2005), which concentrate on the polar regions. town et al. (2007) compared both the isccp and the app-x retrievals with surface-based estimations of cloud cover, from infrared radiometers (pygreometers), at the south pole. they found that during the summer the app-x cloud cover was slightly higher than the pygreometer values, whereas the isccp estimates were too low (by around 30–40%). as well as comparing the cloud cover derived by several different methods, it is interesting to look at the variation of cloud cover with latitude. figure 3 shows the variation with latitude for both isccp retrievals of cloud fraction and surface observations, and it can be seen that cloud cover is at a minimum in the centre of the continent, and increases to a maximum close to the coast, a result that compares well with the subjective impression gained from fig. 1. more recent active satellite-borne instruments, such as lasers (spinhirne et al. 2005), are able to distinguish clouds over a snow and ice surface more easily, but as yet the records from these instruments are short. spinhirne et al. (2005) report values of cloud cover for the month of october 2003 from the geoscience laser altimeter system (glas) instrument carried on the ice, cloud, and land elevation satellite (icesat). although these measurements are limited they do show the same variation in cloud fraction with latitude as the satellite and surface observations (spinhirne et al. 2005: fig. 4), with an increase from the pole towards the coast. fig. 2 monthly fractional cloud cover at the south pole from international satellite cloud climatology project (isccp) satellite retrievals and surface visual observations, using data from the isccp and from hahn & warren (2003). fig. 3 zonally averaged total cloud cover from the international satellite cloud climatology project (isccp) and surface observations for four seasons, using data from the isccp and from hahn & warren (2003). antarctic clouds t. lachlan-cope polar research 29 2010 150–158 © 2010 the author, journal compilation © 2010 blackwell publishing ltd152 cloud microphysical properties measuring cloud microphysical properties, such a particle size, whether solid or liquid (phase) and crystal shape (habit), is, of course, difficult in the extreme antarctic environment. this means less is known about the microphysics of antarctic clouds than of mid-latitude clouds. however, some measurements have been made in antarctica using both remote sensing techniques and occasionally in situ methods. several groups have used lidar to investigate cloud properties using ground-based instruments (smiley et al. 1977; smiley 1980; smiley et al. 1980; del guasta et al. 1993) and airborne instruments (morley et al. 1989). other groups have used radiation measurements to infer microphysical properties, which include using ground-based interferometers (mahesh et al. 2001a, b) and balloon-borne radiometers (stone 1993). another approach is to measure the microphysical properties directly, either by the in situ collection of cloud particle replicas from the clouds that reach down to the surface (ohtake 1978; lachlan-cope et al. 2001; walden et al. 2003, hogan 1975; lawson et al. 2006) or from in situ aircraft measurements (saxena & ruggiero 1990). the flights made by morley et al. (1989) with an airborne lidar clearly showed the difference between the clouds found near the coast and those over the high plateau. on flights from mcmurdo station to the south pole and siple stations, an abrupt change in cloud type was seen as the plane passed from the low-lying ross ice shelf to the higher level polar plateau. the dense midlayer water clouds found over the ross ice shelf were replaced by higher ice clouds, predominantly cirrus. these flights were carried out on one day during january 1986, and so are limited in scope. the lidar used by morley et al. (1989) could not measure polarization, and so they had to infer the phase of the cloud. however, their results can be compared with the more comprehensive measurements made at the south pole and at a coastal station (dumont d’urville) with more advanced ground-based lidar. del guasta et al. (1993) operated a depolarization backscattering lidar at dumont d’urville station during 1989 and 1990. this instrument did not measure clouds lower than 500 m and did not give reliable results for thick clouds, and so their results are biased towards thin, high clouds. given this bias, it is not surprising that they do not seem to have observed any clouds composed solely of water droplets. at temperatures below -25 to -30°c the clouds are predominately ice clouds made up of columnar ice crystals or small ice particles. at temperatures above -25 to -30°c mixed phase clouds are frequently recognized, associated with ice-precipitating mid-level clouds. during the austral winter of 1975, smiley et al. (1980) operated a lidar at the south pole. this instrument was not as advanced as the one used by del guasta et al. (1993), and did not give any information on polarization. however, at the south pole during winter the temperature is such that it can be assumed that most of the clouds observed are ice crystal clouds. this was confirmed by formvar replicas taken at the surface at the same time. smiley often observed low-lying precipitation with higher formation layers. the lidar measurements do not give information on particle size, and there are no aircraft in situ measurements of size in antarctica, except for a limited study by saxena & ruggiero (1990), who measured particle size over the ross ice shelf using a forward scattering spectrometer probe during two flights. however, most information on particle size, and habit, comes from radiometer measurements, both surface-based interferometer and radiometer sondes. radiometer sondes were flown at the south pole in the austral winter months between 1959 and 1963 as part of the us weather bureau’s polar operations project. the data from these flights, consisting of vertical profiles of upward and downward longwave irradiances, were not analysed until stone used them to calculate the properties (emissivity, optical depth and effective radius) of winter clouds (stone 1993). this data set was fairly limited, and after strict quality control criteria were applied to the data only eight flights were left during overcast conditions. he fig. 4 photomicrograph of formvar replicas of cloud particles. the particles were collected on the avery plateau at 15:07z on 4 december 1995. antarctic cloudst. lachlan-cope polar research 29 2010 150–158 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 153 found that generally the cloud base coincided with the top of the surface-based inversion level, which was at a height of 465 m above surface. he found that the clouds he investigated were quite thin, with an effective broadband infrared optical depth of around 1 and longwave emissivity of 0.62. the effective radius of the ice particle was found to be between 4 and 16 mm. mahesh et al. (2001a) used a fourier-transform interferometer to derive cloud parameters at the south pole during 1992. these parameters included cloud-base heights, and although the data set was again somewhat limited, with measurements having only been taken at 1030 and 2230 utc, it does provide a much larger data set than that of stone. mahesh reported a bimodal distribution in cloud height, with values either above or below the inversion height, which does not agree with stone’s rather more limited data set. however, the clouds were rather thin, and it is likely that the uncertainties in both methods are relatively large. mahesh also derived optical depths and particle sizes (mahesh et al. 2001b), and these agreed with those found by stone (1993), with the optical depths being generally less than 1.0 and the particle radii during the winter being generally below 25 mm. ricchiazzi et al. (1995) used a multichannel radiometer based at palmer station (64°46′s, 64°04′w) to calculate cloud optical depths during the spring of 1991. the optical depths that they obtained at this coastal station were much larger than those obtained by mahesh et al. (2001a) at south pole station, and ranged between 20 and 50 mm with a most probable value of 25 mm. in the interior of antarctica and on the high plateau on top of the antarctic peninsula, ice crystals are often observed in the atmosphere close to the surface, and are coded in routine surface observations as diamond dust, which is also known as precipitation from a clear sky. these particles are often larger than cloud particles, and range in radius at the south pole from 2 to 1000 mm (walden et al. 2003). the larger particles have a significant fall speed, depending on their shape, and they can make up a significant part of the accumulation. the formation and development of these crystals is very interesting and important both for the surface mass balance and the radiation balance over the antarctic plateau. several attempts have been made to observe and measure these ice crystals close to the surface. hogan (1975), ohtake (1978), lachlan-cope et al. (2001) and, most recently, walden et al. (2003) have all collected crystals at the surface, and either photographed them directly or made replicas of them using the formvar technique (takahashi & fukata 1988). both hogan and ohtake collected somewhat limited data sets during the summer. however, walden collected a much larger data set comprising the dimensions of about 20 000 crystals during the antarctic winter of 1992. the predominant types of crystals observed were diamond dust in the form of columns (hexagonal prisms) or hexagonal plates. he also observed blowing snow particles and snow grains precipitating from clouds. figure 4 shows a microphotograph of hexagonal plates collected on the avery plateau; this image was used by lachlan-cope et al. (2001) in their study of clouds over the antarctic peninsula. occasionally, very long crystals were observed that were 1000 mm in length but only 10 mm in width. such crystals are known as shimizu crystals (shimizu 1963). kikuchi & hogan (1979) looked at the variation of width to length of the crystals observed on one day in 1975, and found that the columnar type prevailed, and that the ratio of length to width varied cyclically with a period of around 2 h, although they offered no explanation for this observation. walden calculated the effective radius of the entire size distribution of the diamond dust to be around 12 mm, and this agrees well with the effective radius inferred from radiation measurements at the south pole (see above). walden found diamond dust in the form of both plates and columns at temperatures below -40°c, supporting the laboratory results of bacon et al. (2003), which showed that factors other than humidity and temperature are important in determining the habit of a crystal. as well as measuring diamond dust, walden et al. (2003) collected blowing snow particles and snow grains. the blowing snow particles are lifted from the surface when the wind speed is greater than about 7 m s-1, a process that is often assisted by saltation—when a precipitating particle dislodges one or more particles from the surface. this process means that the blowing snow particles tend to have undergone several collisions, and tend to be rounded, and so are easily distinguished from the more regular diamond dust crystals. it is interesting to note that walden et al. (2003) found particles that appeared to be the same shape as blowing snow particles on days when the average wind speed was less than 7 m s-1 and when the weather observers did not report any blowing snow. they interpreted these crystals as residual blowing snow crystals that continued to settle for day or two after the wind speed had dropped. it is interesting that blowing snow particles have such a long lifetime in the atmosphere, and it is possible that they play a further role as ice nuclei within clouds. the snow grains observed by walden et al. (2003) were crystals precipitating from clouds, and tend to be made up of clusters of plates or bullet crystals, and are as such are easy to distinguish from the single diamond dust crystals. more recently, advanced particle imagers of the sort developed for use in aeroplanes have been deployed at the south pole (lawson et al. 2006) during early february 2001. this instrument, known as a cloud particle antarctic clouds t. lachlan-cope polar research 29 2010 150–158 © 2010 the author, journal compilation © 2010 blackwell publishing ltd154 imager (cpi), produces high-resolution images of cloud particles. these images mean that it is possible to investigate the habit of the crystals. in the lawson et al. (2006) study, 30% of the particles were found to be rosette shaped, 45% were diamond dust (columns, thick plates and plates) and 25% had an irregular shape. this method measures the crystal radius directly, not an effective radius, and the distribution of maximum crystal size was found to have a peak that varied between 50 and 100 mm (when looking at the number distributions). converting the observed maximum dimension into an equivalent radius depends on both the volume and surface area. lawson et al. (2006) used relationships to determine the volume and area from the parameters that can easily be measured from the cpi images. they found that the resulting equivalent radius was generally less than 50 mm, with a maximum in the size distribution around 25 mm. they did not calculate an effective radius, so it was not possible to compare these results directly with those obtained from the radiation measurements, although they were similar to measurements made by walden et al. (2003). lawson et al. (2006) reported that the crystals they observed at the south pole appeared to be similar to those observed by the same instruments within cirrus clouds. they did observe blowing snow on at least one occasion, but did not have enough data to correlate the occurrences of blowing snow with the wind speed. cloud particle sizes measured in antarctica are summarized in table 1. few measurements of cloud-forming nuclei have been made in antarctica because of the difficulty in making the necessary measurements in remote areas. as the sources of such nuclei are likely to be limited, and possibly unique to the continent, it is very difficult to use results from other parts of the world. even measurements in the arctic are difficult to apply to the antarctic, as proximity of snow-free land masses in the north mean that arctic cloud-forming nuclei are likely to have a very different source. during 1994 saxena (1996) measured cloud condensation nuclei at palmer station and at times found elevated concentrations. however, these were similar to results from the arctic. of course in the cold polar regions clouds are often composed solely of ice, or are of mixed phase, and so the availability of ice nuclei is important. saxena & weintraub (1988) measured ice-forming nuclei at palmer station using a filter technique, and found ice nuclei concentrations that were similar to those measured elsewhere, although the values they reported did range over several orders of magnitude. lachlan-cope et al. (2001) have inferred the number of ice nuclei from measurements of ice crystals made on the spine of the antarctic peninsula. they found that the number of ice crystals was much larger than those predicted by the equations derived by fletcher (1962) for mid-latitudes. however, these results were obtained for samples collected close to the surface on the antarctic peninsula, and may not be representative for the antarctic atmosphere as a whole. identifying the source of cloud-forming nuclei can be difficult; however, two papers have looked at this problem for antarctica. the source of ice nuclei at high southern latitudes has been investigated by saxena & weintraub (1988), who found that the elements silicon, zinc and potassium, presumably combined with other elements and water, appeared to act as good ice nuclei in the filter samples taken at palmer station on the antarctic table 1 a summary of the cloud particle sizes measured at various locations in antarctica. where/who when height size (mean) phase shape south pole / lawson et al. (2006) february 2001 surface 17 mm (rva) ice diamond dust 10.5 mm (rva) column 25.3 mm (rva) budding 27.9 mm (rva) rosette 19.2 mm (rva) complex 17.8 mm (rva) plates 27.2 mm (rva) thick plates 17.0 mm (rva) rosette blowing snow south pole / walden et al. (2003) winter 1992 surface 12.2 mm (reff) ice diamond dust 11.0 mm (reff) blowing snow 23.6 mm (reff) snowgrains 10.7 mm (reff) all crystals south pole / stone (1993) 1959–1963 140–840 m a.s.l. 4–16 mm (reff) ice all crystals south pole / mahesh et al. (2001b) 1992 above surface 15 mm (reff)—mode ice byrd station (80°s, 120°w) / shimizu (1963) 1961 surface 1000 mm (length) ice shimizu crystal (long column) avery plateau (67°s, 65.5°w) / lachlan-cope et al. (2001) 1995 surface 20–200 mm ice all crystals 10–50 mm water drops antarctic cloudst. lachlan-cope polar research 29 2010 150–158 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 155 peninsula (64°46′s, 64°03′w). saxena (1983) has also looked at biological sources for cloud condensation nuclei. he found evidence for biogenic nuclei during flights over the ross ice shelf, and he speculated that biological material from the surrounding oceans are one of the important sources for producing cloud-active aerosols. the radiative effects of clouds the phase, size distribution and concentration of cloud particles affect the transfer of radiation, both longwave and shortwave, through the clouds, and so clouds can have a major influence on the net radiation balance at the surface. this is true even over a high-albedo snow surface (ambach 1974). in the antarctic, pavolonis & key (2003) have shown, using satellite data, that clouds have a warming influence on the surface over the continent in all months. over the ocean, clouds only had a warming effect from march to october, whereas during the antarctic summer, cloud cooled the surface. similar results were found by fitzpatrick & warren (2007) using measurements made on the rsv aurora australis. these results also generally compare well with in situ measurements taken at neuymayer station in 1993, and at the south pole in 1986–87, with the biggest differences being found in shortwave radiation during the summer months. of course this is to be expected, as shortwave radiation is much more sensitive to the phase, shape and size of the cloud particles, and is only important during the summer months. cloud radiative effects can have a large impact on the earth’s climate system by controlling the passage of radiation through the atmosphere. climate model studies show that local cloud anomalies can have a global impact (gordon et al. 2000). it is therefore important that clouds are correctly represented within climate models, and that local variations in cloud properties are represented. several studies have looked at the role of antarctic clouds within the present generation of climate models, and in particular how changes in the representation of the microphysical properties of antarctic clouds can affect the global climate. lubin et al. (1998) investigated the effect of ice clouds over antarctica in the national center for atmospheric research (ncar) community climate model version 2 (ccm2). they found a large difference between the modified model and the standard version of ccm2, which had water-droplet clouds both over antarctica and in the tropics, and even in the extratropics of the northern hemisphere. the standard version of ccm2 has liquid cloud everywhere, and lubin et al. (1998) used a simple modification for this that may not represent reality, although they did demonstrate the sensitivity of the atmosphere to changes in the phase of the cloud particles. briegleb & bromwich (1998) investigated the polar radiation budget in the more sophisticated version 3 of the ncar community climate model (ccm3), which allows for a cloud particle ice fraction that is temperature dependant below 0°c. however, the improved cloud microphysics did not seem to improve the radiation budget over antarctica, and briegleb & bromwich (1998) reported that the accuracy of the top of atmosphere radiation balance in ccm3, compared with earth radiation budget experiment (erbe) data, was worse when compared with ccm2 results. hines et al. (2004) have used used an improved progonostic cloud scheme in ccm3, but found that it was not a clear improvement over earlier schemes. of course, one of the problems with these studies is the lack of in situ measurements in antarctica to validate the “improved” cloud microphysical representations. conclusions the isolation of antarctica and the extreme nature of its climate mean that the study of clouds in that region is less advanced than in many other regions of the world. the surface synoptic network is on the whole more widely spaced over antarctica, with large areas of the continent without any in situ observations. satellite measurement of cloud parameters is also difficult over a snowy surface. this must mean that there is some doubt over the values of seasonal and area coverage of cloud given in the literature. the few cloud microphysics measurements that have been made hint that the number of ice-forming nuclei may be several orders of magnitude greater than expected from the simple parameterization of ice nuclei number developed from mid-latitude observations (lachlan-cope et al. 2001), although at the moment there is no obvious source for these nuclei. also, the work of saxena (1983) suggests a biological source for ice nuclei, and this hints at possible complex biological feedbacks at high southern latitudes. much more work is needed to investigate the role of cloud-forming nuclei in the antarctic and their source, particularly as the cloud microphysics has a profound effect on the radiation balance of the atmosphere. it is therefore important to represent the cloud microphysics correctly within climate models. the present generation of cloud models use cloud parameterization developed from mid-latitude observations. however, because of the extreme environment and isolation of the antarctic, it is unlikely that cloud observations made in other regions will be representative of antarctica, and it is vital that in situ observations are made of antarctic clouds in the future. antarctic clouds t. lachlan-cope polar research 29 2010 150–158 © 2010 the author, journal compilation © 2010 blackwell publishing ltd156 this review of antarctic clouds highlights both their importance and the lack of observations. it is hoped that the latest generation of meteorological satellites, carrying active instruments, will go some way to addressing this problem, but these observations must be backed up with in situ measurements made with both manned and unmanned aircraft. acknowledgements the author appreciates the support of the antarctic meteorological research center, university of wisconsin–madison, for the satellite composite shown in fig. 1 (matthew lazzara and elena willmot, us national science foundation grant numbers ant-0537827 and ant-0838834). references ambach w. 1974. the influence of cloudiness on the net radiation balance of a snow surface with high albedo. journal of glaciology 13, 73–84. bacon n.j., baker m.b. & swanson b.d. 2003. initial stages in the morphological evolution of vapour-grown ice crystals: a laboratory investigation. quarterly journal of the royal meteorological society 129, 1903–1927. briegleb b.p. & bromwich d.h. 1998. polar radiation budgets of the mcar ccm3. journal of climate 11, 1246–1269. del guasta m., morandi m. & stefanutti l. 1993. one year of cloud lidar data from durmont d’urville (antarctica) 1. general overview of geometric and optical properties. journal geophysical research—atmospheres 98, 18 575–18 587. fitzpatrick m.f. & warren s.g. 2007. the relative importance of clouds and sea ice for the solar energy budget of the southern ocean. journal of climate 20, 941–954. fletcher n.h. 1962. physics of rain clouds. cambridge: cambridge university press. gordon c., cooper c., senior c.a., banks h., gregory j.m., johns t.c., mitchell j.f.b. & wood r.a. 2000. the simulation of sst, sea ice extents and ocean heat transports in a version of the hadley centre coupled model without flux adjustments. climate dynamics 16, 147–168. hahn c.j. & warren s.g. 2003. cloud climatology for land stations worldwide, 1971–1996. numerical data package ndp-026d. oak ridge, tn: carbon dioxide information analysis center, us department of energy. hahn c.j., warren s.g. & london j. 1995. the effect of moonlight on observations of cloud cover at night, and application to cloud climatology. journal of climate 8, 1429–1446. hatzianastassiou n., cleridou n. & vardavas i. 2001. polar cloud climatologies from isccp c2 and d2 datasets. journal of climate 14, 3851–3861. hines k.m., bromwich d.h., rasch p.j. & iacono m.j. 2004. antarctic clouds and radiation within the ncar climate models. journal of climate 17, 1198–1212. hogan a.w. 1975. summer ice crystal precipitation at the south pole. journal of applied meteorology 14, 246–249. ipcc (intergovernmental panel on climate change) 2007. summary for policymakers. in s. solomon et al. (eds.): climate change 2007. the physical science basis. contribution of working group i to the fourth assessment report of the intergovernmental panel on climate change. pp. 1–18. cambridge: cambridge university press. kikuchi k. & hogan a.w. 1979. properties of diamond dust type ice crystals observed in summer season at amundsen–scott south pole station, antarctica. journal of the meteorological society of japan 57, 180–190. lachlan-cope t., ladkin r., turner j. & davison p. 2001. observations of cloud and precipitation particles on the avery plateau, antarctic peninsula. antarctic science 13, 339–348. lawson r.p., baker b.a., zmarzly p., o’connor d., mo q., gayet j. & shcherbakov v. 2006. microphysical and optical properties of atmospheric ice crystals at south pole station. journal of applied meteorology and climatology 45, 1505–1524. lubin d., chen b., bromwich d.h., somerville r.c.j., lee w.-h. & hines k. 1998. the impact of antarctic cloud radiative properties on a gcm climate simulation. journal of climate 11, 447–462. mahesh a., walden v.p. & warren s. 2001a. ground-based remote sensing of cloud properties over the antarctic plateau. part i: cloud-base heights. journal of applied meteorology 40, 1265–1278. mahesh a., walden v.p. & warren s. 2001b. ground-based remote sensing of cloud properties over the antarctic plateau. part ii: cloud optical depths and particle sizes. journal of applied meteorology 40, 1279–1294. morley b.m., uthe e.e. & viezze w. 1989. airborne lidar observations of clouds in the antarctic troposphere. geophysical research letters 16, 491–494. ohtake t. 1978. atmospheric ice crystals at the south pole in summer. antarctic journal of the united states 13, 174–175. pavolonis m.j. & key j.r. 2003. antarctic cloud radiative forcing at the surface estimated from the avhrr polar pathfinder and isccp d1 datasets, 1985–93. journal of applied meteorology 42, 827–840. rasmussen e. & turner j. (eds.) 2004. polar lows: mesoscale weather systems in polar regions. cambridge: cambridge university press. ricchiazzi p., gautier c. & lubin d. 1995. cloud scattering optical depth and local surface albedo in the antarctic: simultaneous retrieval using ground-based radiometry. journal of geophysical research—atmospheres 100, 21 091–21 104. rossow w.b. & schiffer r.a. 1999. advances in understanding clouds from isccp. bulletin of the american meteorological society 80, 2261–2287. antarctic cloudst. lachlan-cope polar research 29 2010 150–158 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 157 saxena v.k. 1983. evidence of the biological nuclei involvement in antarctic coastal clouds. journal of physical chemistry 87, 4130–4134. saxena v.k. 1996. bursts of cloud condensation nuclei (ccn) by dissipating clouds at palmer station, antarctica. geophysical research letters 23, 69–72. saxena v.k. & ruggiero f.h. 1990. antarctic coastal stratus clouds: microstructure and acidity. antarctic research series 50, 7–18. saxena v.k. & weintraub d.c. 1988. ice forming nuclei concentrations at palmer station, antarctica. in p. wagner & g. vali (eds.): proceedings of the twelfth international conference on atmospheric aerosols and nucleation, held at the university of vienna, austria, august 22–27, 1988. lecture notes in physics 309. pp. 679–682. berlin: springer. shimizu h. 1963. long prism crystals observed in the precipitation in antarctica. journal of the meteorological society of japan 41, 305–307. smiley v.n. 1980. lidar measurements in antarctica. antarctic journal of the united states 15, 188–190. smiley v.n., morley b.m. & warburton j.a. 1977. lidar and replication studies of the ice crystal precipitation at the south pole. antarctic journal of the united states 12, 166–167. smiley v.n., whitcomb b.m., morley b.m. & warburton j.a. 1980. lidar determination of atmospheric ice crystal layers at south pole during clear-sky precipitation journal of applied meteorology 19, 1074–1090. spinhirne j.d., palm s.p. & hart w.d. 2005. antarctic cloud cover for october 2003 from glas satellite lidar profiling. geophysical research letters, l22s05, doi: 10.1029.2005gl023782. stone r.s. 1993. properties of austral winter clouds derived from radiometric profiles at the south pole. journal of geophysical research—atmospheres 98, 12 961–12 971. takahashi t. & fukata n. 1988. ice crystal replication with common plastic solutions. journal of atmospheric and ocean technology 5, 129–135. town m.s., walden v.p. & warren s.g. 2007. cloud cover over the south pole from visual observations, satellite retrievals, and surface-based infrared radiation measurements. journal of climate 20, 544–558. walden v.p., warren s.g. & tuttle e. 2003. atmospheric ice crystals over the antarctic plateau in winter. journal of applied meteorology 42, 1391–1405. wang x. & key j.r. 2005. arctic surface, cloud, and radiation properies based on the avhrr polar pathfinder dataset. part 1: spatial and temporal characteristics. journal of climate 18, 2558–2574. antarctic clouds t. lachlan-cope polar research 29 2010 150–158 © 2010 the author, journal compilation © 2010 blackwell publishing ltd158 research note cladina stellaris (opiz) brodo as a bioindicator of atmospheric deposition on the kola peninsula, russia k r y s t y n a grodzinska, barbara godzik and piotr bienkowski grodziriska. k . , godzik. b. & bierikowdi, p. 1999: clutlinu .vte/luris (opiz) brodo as a hioindicator of atmospheric deposition on the kola peninsula, russia. polur reseurch 18(1). 105-1 10. concentrutions of 16 elements (al, cd. co, cr. cu. fe. mn, ni, ph, zn. c. n. s . p, ca, mg) were determined in the lichen clatlina src4laris (opil) brodo collected from 26 localities on the kola peninsula. concentration5 were higher closer to the emission sources. in arctic regions affected by local emissions. lichenz, c:in he recommended ti\ seiisitive indicators of atmospheric pollution. k . grod:insku d; b. god:ik. w . s s r f r r 117.uitiite of botany, poli.rh acudetny of sciences, liihic: 40, 31 -512 kruk(iw, polund; p. b i e i k o i u k i . institute of e c o / o , y y , p o l i s h acadeniy o / sciences, dziekunciv les’tiy iieur w u t x a i v t r . 0.i-092 toniiuriki. poliiriil. introduction the kola peninsula is one of the areas in the northern hemisphere polluted by heavy metals and sulphur (kozlov et al. 1992; tikkanen et al. 1992: makinen 1994: ruhling 1994; alexeyev 1995: baklanov et al. 1995; glazov et al. 1995; kelley et al. 1995: moiseenko 1995). the primary sources of pollution are: copper-nickel smelters located near the towns of monchegorsk (severonickel smelter) and zapolyami (pechenganickel smelter). other operations on the kola peninsula include an aluminium smelter in kadalaksha, iron and apatite mines in kirovsk and olenegorsk, and coal burning and naval installations in murmansk (fig. 1). the kola peninsula is also affected by long-range transport of pollutants; however, that contribution is negligible compared with local sources. yearly copper emissions on the kola peninsula exceed two thousand tonnes (severonickel two thousand, pechenganickel 180 tonnes) and nickel emissions exceed three thousand tonnes (sever onickel three thousand, pechenganickel 300 tonnes) (makinen 1994; jaffe et al. 1995). total so2 emissions are approximately 600 thousand tonnedyear (jaffe et al. 1995). the regional depositions of cu and ni are: 0.15 and 0.35 k g h d y e a r respectively (alexeyev 1995). average sulphur deposition on the kola peninsula is approximately 0.7-1 .o g/m’/year, and near the local sources is even as high as 30glm’lyear (moiseenko 1995). sulphur depositions are higher than critical values across most of the kola peninsula (koptsik & koptsik 1995). the kola peninsula is part of the fenno scandian crystalline shield, built of palaeozoic granitoids and metamorphic crystalline shields (skiba 1994). podzol soils and weakly formed soils are most common. they are acidic (ph about 4). with about 50% organic matter and a c/n ratio of about 30. the concentration of heavy metals is high (iron max. 18,000 pg/g d.wt, copper max. 2000 pg/g d.wt., nickel max. about 2000 pg/g d.wt. (s. skiba 1994, unpubl. data). the topography of the kola peninsula varies considerably. while areas along the coast of the white and barents seas are below 2 0 0 m a d . , most of the land is between 200 and 500 m a.s.1. mountains, with the highest peak at 1208 m a d . , cover a small area in the middle of the peninsula. smelter complexes are located at altitudes of 100 350 m a.s.1. (makinen 1994). the peninsula lies mostly within the cool temperate zone; only the north-eastern part is included in the polar zone. the average summer temperature is about 8 1 4 t . annual precipitation averages approximately 400 mm. the growing 3 2' 36' season is short (120-125 days). south-westerly winds predominate during the winter; i n summer they are often north-easterly (luzin et al. 1994; makinen 1994). the vegetation belongs to the northern boreal and arctic alpine zones and is represented by forest tundra (spruce, scotch pine, birch) or treeless tundra and mires. close to the industrial areas the vegetation is seriously da maged: dying forests are common (makinen 1 994). because of their anatomical structure, lichens and mosses have a great ability to accumulate various chemical elements, including air pollu tants, making them useful for assessing environ mental contamination (markert 1992). various lichen and moss species have been used as indicators of environmental pollution i n arctic areas by ruhling et al. (1987), grodzinska & godzik (1991), heino et al. (1992), grodzinska et al. (1993). makinen (1994). steinnes et al. (1994) and glazov et al. (1995). cladina stetluris (opiz) brodo (= cladonin alpestris [l.] rabenh.) has been used as a sensitive bioindicator of heavy metal pollution several times (pakarinen et al. 1978; nuorteva et al. 1986; kortesharju et al. 1990; nuorteva 1990: glazov et al. 1995). according to folkeson & andersson bringmark (1988), this species is an especially effective accumulator of cu and zn. the aim of this study was to determine the 40' f i g . 1. the kola peninsula: major urban and industrial sources. concentrations of 16 elements, mostly pollutants, in c. sfelluris, which is common in the area. methods during summer 1992, lichen samples were collected along two transects which were located along the road network, and spanned forest tundra and treeless tundra ecosystems. the first transect (ca. 200 km) ran southward from zapolyarni (the location of the pechenganickel smelter), via murmansk, to monchegorsk (severonickel smel ter). the second (ca. l50km) ran eastward from murmansk to dalnye zelentsy (fig. 2 ) . the sampling density was about one composite sample every 10-15 km. no samples were collected within 5 km of the smelters. sampling sites were no less than 150 m and no more than 200 m from the roads. at each sampling site. three subsamples were taken within an area of 20-30 m2, and then combined in one collective sample of 20-25 g d.wt. sampling and sample handling were per formed without polyethylene gloves. the samples stored i n the field i n polyethylene bags were transported to the laboratory and cleaned of litter and other debris. unwashed samples (whole lichen) were dried at 600'c, then homogenized. samples of 0.5-0.6 g d.wt (icp-as) claditza stellaris (opiz) brodo cis a bioindicator of atmospheric deposition 107 fig. 2. the study area with sampling sites. north-south (sites 1-15) and west-east (sites 16-26) transects. or 5-10 mg (elemental analyser chns-0) were digested in the mixture of spectral pure concen trated acids (hno3/hc1, proportion 2: 1) i n microwave cem-mds 2000. digestion samples were then diluted to about 50 ml i n bidistilled water. thirteen elements (al, cd, co, cr, cu. fe, m n , ni, pb, zn, p, ca, mg) were analysed by plasma mass spectrometry (icp-aes, model polyvac) and the other three elements (c, n, s) by elemental analyser (chnsco, fisons instruments, model 1108). the analyses were done at the institute of ecology, polish academy of sciences, in dzieka n6w. results the concentration of heavy metals in c. stelluris varied among the sites (fig. 3). ranges were as follows (pg g-i): cd: dl-2.86; co: 0.61-19.90; cr: 0.79-10.2; cu: 5.34-428; fe: 255-5648; mn: 6.48-266: ni: 9.08-486; pb: 1.8245.6: zn: 11.4 57.6; and al: 214-1665. the greatest variation among sites was observed with cu, n i and mn. there was much less variation with pb, fe, cd, co and cr, and the least with zn. the maximum concentrations of most of the metals were found i n lichen collected close to the monchegorsk and zapolyarni smelter complexes (fig. 3 . sites 1 . 1 1 15). high values of cd, pb and co were also found in samples from sites located closer to the barents sea (fig. 3, sites 23-26). the concentration of zn and cr in c. stelluris was less dependent on the distance from emission sources than other ele ments. such dependence was not found for al. the carbon content in the lichen ranged from ca 32-50%. depending on the site, and nitrogen content from 0.44 to 0.94%, with the highest values found near monchegorsk (table i ) . the mean c/n ratio was 66 & 1 1 (min. 45.10. max. 93.18). sulphur concentrations in c. stelluris were the highest near the smelters i n monchegorsk (max. 982 pg g-i). calcium accumulation in the lichen was clearly higher near the smelters (2000 pg g-', max. 3781 pg g-'), while at other sites i t generally remained 1000 pg g-' (min. 3 12 pg g-'). phosphorus concentrations fluctuated from 264 to 101 5 pg g-' and magnesium from 235 to 1180 pg g-' without a clear dependence on distance from emissions sources (table 1). discussion i n this region air pollutants are transported up to 100 km, with the wind blowing from the south west in summer and the north in winter. the samples of c. stelluris collected along the north 108 k . grudziriskn et 01. transect n s 200 ::: i-:-+ an,-.jn 0 0 i 2 3 4 5 6 7 a 9 1 0 1 1 1 2 1 3 1 4 1 5 6qq cu 400 1 n i 2 3 4 5 6 7 a s 1 o 1 1 1 2 1 3 1 4 1 5 ::: 100 lill 0 ~ , c l 0 0 0 n 0 il 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 6000 i fe r-i 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 ~ 4 1 5 n 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 3 i n cd 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 transect w e o--------- 16 17 18 19 20 21 22 23 24 25 26 nlnooo,a17n-o 16 17 18 19 20 21 22 23 24 25 26 ,n,n,n,n 0 0 el 0 n ci 16 17 18 19 20 21 22 23 24 25 26 16 17 18 19 20 21 22 23 24 25 26 16 17 18 19 20 21 22 23 24 25 26 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 16 17 18 19 20 21 22 23 24 25 26 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 n 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 cladilia stellaris (opi:) brodo cis a oioindicator of atniosplieric depositiori 109 tc7blr i . concentrations of essential elements (% and pg g i d. wt) in clclditicl srel1uri.s collected along north-south (nos. 1-14) and west-eat (nos. 1 6 2 6 ) transects on the kola peninsula. s ca me p locality n 9 c% cin i v € i p€ g~ ' pg g ' p€ €-i 1 2 3 4 5 6 7 x 9 10 i i i 2 13 14 16 17 18 19 20 ? i 26 7 7 -_ 0.44 0.54 0.69 0.62 0.72 0.59 0.65 0.6') 0.64 0.65 0.75 0.94 0.61 0.86 0.63 0.71 0.76 0.64 0.58 0.5 i 0.58 0.60 41.00 44.59 42.58 43.27 44.94 41.37 44.08 42.47 42.64 41.67 42.40 31.92 50. 19 43.49 42.32 40.56 40.35 40 75 42.04 42.53 42.74 40.03 93. i 8 62 i 82.57 409 61.71 537 69.79 348 55.5y 434 76. i6 498 63.56 609 63.88 660 66.35 475 65.60 54 1 55.56 468 45. 10 882 49.87 55 i 58.36 982 69.03 639 59.60 463 53.36 549 63.04 339 70.2s 315 x2.13 301 73.32 468 71.23 449 i195 895 1018 312 1116 627 2348 i539 719 928 1039 251 i 2322 3781 i264 561 939 711 729 494 916 1258 480 453 480 235 507 331 1 i 8 0 602 323 333 396 697 810 843 480 888 840 456 438 290 496 589 313 570 354 518 398 612 820 41 1 614 490 1015 715 516 655 497 55 i 36 i 305 264 447 482 south and west-east transects are within the range of metallic dust depositions throughout the year. the concentration of heavy metals and sulphur i n the air and i n precipitation on the kola peninsula is high and is correlated with the distance from emission sources (ayras et al. 1995; glazov et al. 1995; jaffe et al. 1995; kelley et al. 1995: reimann et al. 1995). this accounts for the varying concentrations found in the species studied since lichens obtain minerals as well as pollutants from precipitation and from dry deposi tion (tyler 1990). levels of most of the chemicals i n the lichen studied. particularly the heavy metals, were related to the distribution of emission sources. the highest accumulation of metals i n c. stellrtris was found near smelters, iron ore mines and processing plants (monchegorsk. ole negorsk, nikel, zapolyarni). why concentrations of cd, pb and c o in lichen collected near the barents sea were higher than in samples from sites closer to the emission sources is difficult to explain. the large shipping port at murmansk may be an additional source of these elements. references alexeyev. v . a. 1995: impacts of air pollution on far north forear vegetation. the science of rhr tom/ en\,irontnenr /60/ 161,605-617. ayris, m.. de caritat, p., chekushin, v. a,, niskavadra, h. & reimann. c. 1995: ecogeochemical investigation, kola peninsula: sulphur and trace element content in snow. wafer, air mid soil pollrction 8.5. 749-754. baklanov. a. a,, klyuchnikova. e. m.. limkina. c. yu.. rigina, 0. y u . & rodyushkina, 1. a. 1995: airborne sulphur pollution i n industrial districts of the kola peninsula (abstract). arid reigit '95:) conferenre absrruct book. p. 452. dordrecht, netherlands: kluwer academic publ. folkeson, l., ander~son-bringinark, e. 1988: impoverishment of vegetation i n a coniferous forest polluted by copper and zinc. cunrniinn j. bor. 66. 417428. glazov, m. v . , kdrdban, r. t.. leontyeva, 0. a. & gytarsky. m. l. 1995: the influence of air pollution on forest ecosystems i n pechenganickel region of kola peninsula. arrhiivritn 0cliron.v srorlowiska 2, 53-62. grodziliska, k . & godzik. 8.1991: heavy metal and sulphur in mosses from southern spitsbergen. fokur research 9(2j, i 33140. grodziliska, k., godzik, b. & szarek, g . 1993: heavy metals and sulphur in lichens from southern spitabergen. frrtgni. flor. grohor. suppl. 2(21, 699-708. f i g 3 . north-south (sites 1-15) and west-east (sites 16-16) gradients of heavy metal (ni. cu, mn, fe, co. cd. pb, zn, cr) and al concentrutions (pg g' ) in lichen samples collected along trilnsects running southward from zapolyarni. via murniansk, to monchegorsk and eastward from murniansh to dalnye zeleiil\y. 1 10 k . grodziiiska et al. heino, s., anttonen, s., wulf, a. & karenlanyi. l. 1992: nickel and copper accumulation in the lichen cerruria nivalis ( l . ) ach. in lapland. symposium on the state of the environ mental monitoring in northern fennoscandia and the kola peninsula, 6 8 october 1992, rovaniemi. finland (e. tikkanen et al., eds.). arctic centre publications 4 . p. 269. jaffe, d., cerundolo. b., rickers, .i., stolzberg, r. & baklanov, a. 1995: deposition of sulfate and heavy metals on the kola peninsula. the science of the tot01 environment 160/16/, 127-1 34. kelley, j . a,, jaffe, d. a,. baklanov. a. & mahura, a. 1995: heavy metals on the kola peninsula: aerosol size distribution. the science of the t o t d ein~ironntent 160/161. 135-138. koptsik, g. & koptsik. s. 1995: critical loads of acid deposition for forest ecosystems in the kola peninsula. water, air und soil pollutiun 85, 2553-2558. kortesharju, j., savonen, k. & saynatkari, t. 1990: element contents of raw humus, forest moss and reindeer lichens around a cement works in northern finland. ann. but. fennici 27, 221-230. kozlov, m. v.. hankioja, e. & yarmishko, v. t. (eds.) 1992: aeriul pollution in kola peninsula. procredings of rhe irrrernutional workshop. 14-16 april 1992, st. petersburg. luzin, g. p., pretes, m. & vnsiliev. v. 1994: the kola peninsula: geography, history and resources. arctic 4 7 ( 1 ) , i 1 s. markert, b. (ed.) 1992: plant.\ a,\ bioinorritorsr irrdicarors f o r heiivy nietals iii the terrejtria1 environnrerrr. weinheim: vch verlagsgesselschaft mbh. mikinen, a. 1994: biomonitoring of atmospheric deposition in the kola peninsula (russia) and finnish lapland. based on the chemical analysis of mosses. 83 pp. helginki: ministry of the environment. yliopistopaino. moiseenko, t. 1995: critical loads of so4 for surface waters in the kola region of russia. wurer, air on(/ soil po1/~tio11 85. 4 6 9 4 7 3 . nuorteva. p. 1990: metal distribution patterns and forest decline. seeking achilles' heels for metals in finnish forest biocoenoses. publications of the depurtinetzt qf environ nwntnl conservrition ui the universih. of helsinki 1 1 , 1-77. nuorteva, p., autio, s., lehtonen, j.. lepisto. a,, ojala. s., seppinen, a,. tulisalo, e., veide, p., viipuri. j. & willamo. r. 1986: levels of iron, aluminium, zinc, cadmium and mercury in plants growing in the surroundings of an acidified and a non-acidified lake in espoo. finland. ann. bot. fennici 23.333-340. pakarinen, p.. mikinen, a. & rinne. r . j . k. 1978: cltidoniu arlntsculu and clu~lwiia tniris in eastern fennoscandia. ann. boi. fentiiri 15, 281-286. reimann, c., niskavaara. h., de caritat, p.. ayrhs, m., chekushin, v. a. & finne. t. e. 1995: snowpack sampling to fingerprint environmental contamination in the surround ings of the nickel smelter at nikel, kola peninsula. russia. i n wilken, r. d. et al. (eds.): inrerr~ationd conference heu1.y metals in the enciroimient. vol. 1. pp. 84-87. hamburg: cep consultants lid. riihling, a. (ed.) 1993: atmospheric heavy metal deposition in europe -estimation based on moss analysis. nord 9, 1-53. riihling. a,, rasmussen, l.. pilegaard, k., mikinen. a. & steinnes. e. 1987: nordic countries i n 1985 monitored by moss analysis. nord 21, 1-44. skiba, s. 1994: soils of the dalnye zelentsy tundra region in the northern part of the kola peninsula (russia). wyprait:,' g e o g r u f i c x r i i u spifsbergerr (geojiriiphicul expedition on spifsbergerr). pp. 71-77. lublin: uniwersytet marii curie sklodowskiej (maria curie-sklodowska university ). steinnes, e.. hanssen, j. e., rambnk, .i. p. & vogt, n. b. 1994: atmospheric deposition of trace elements i n norway: temporal and spatial trends studied by moss analysis. ware,; airand soil pullrctiorr 74, 121-140. t i k a n e n , e.. varmola, m. & katermaa. t. (eds.) 1992: symposium on the state of the environmental monitoring i n northern fennoscandin and the kola peninsula. 6-8 october 1992. rovaniemi, finland. 369 pp. a r d c centre publications 3. tyler, g. 1990: bryophytes and heavy metals: a literature review. bor. linnean. soc. 104, 231-253. doi:10.3402/polar.v35.26029 r e s e a r c h / r e v i e w a r t i c l e barents sea polar bears (ursus maritimus): population biology and anthropogenic threats magnus andersen & jon aars norwegian polar institute, fram centre, po box 6606 langnes, no-9296 tromsø, norway keywords top predator; environmental threats; climate warming; contamination; disturbance; habitat change. correspondence magnus andersen, norwegian polar institute, fram centre, po box 6606 langnes, no-9296 tromsø, norway. e-mail: magnus.andersen@npolar.no abstract this paper examines how anthropogenic threats, such as disturbance, pollution and climate change, are linked to polar bear (ursus maritimus) population biology in the svalbard and barents sea area, with the aim to increase our understanding of how human activity may impact the population. overharvesting drastically reduced the population of polar bears in the barents sea region from about 1870 to 1970. after harvesting was stopped*in 1956 in russia and 1973 in norway*the population grew to an estimated 2650 individuals (95% confidence interval 1900�3600) in 2004, and maternity denning in the svalbard archipelago became more widely distributed. during recent decades, the population has faced challenges from a variety of new anthropogenic impacts: a range of pollutants, an increasing level of human presence and activity as well as changes in ice conditions. contaminants bioaccumulate up through the marine food web, culminating in this top predator that consumes ringed, bearded and harp seals. females with small cubs use land-fast sea ice for hunting and are therefore vulnerable to disturbance by snowmobile drivers. sea-ice diminution, associated with climate change, reduces polar bears’ access to denning areas and could negatively affect the survival of cubs. there are clear linkages between population biology and current anthropogenic threats, and we suggest that future research and management should focus on and take into consideration the combined effects of several stressors on polar bears. the history of polar bear (ursus maritimus) science has involved extensive international cooperation in research and management over the last 50 years (larsen & stirling 2009). polar bears are widely distributed across the circumpolar arctic, including regions of drifting sea ice. the world population size is suggested to be 20 000�25 000 animals, comprising 19 subpopulations (obbard et al. 2010). polar bears are specialized predators that mainly feed on seals and other marine mammals (stirling & archibald 1977; smith 1980; derocher et al. 2002; iversen et al. 2013). characterized as marine mammals themselves, polar bears rely on sea ice not only to gain access to their prey but also to travel between hunting and denning habitats. though they den on land throughout most of their range, sea ice is also important for reproduction in most polar bear populations because males search the sea ice in spring to locate mates (molnár et al. 2008). polar bears are highly mobile and individuals can roam over large areas. however, significant variations in movement behaviours have been documented even within populations, with home ranges varying from less than 200 km 2 to almost 400 000 km 2 in the barents sea region (mauritzen et al. 2001). in svalbard, some bears move over the entire barents sea during their annual seasonal movements while others remain within the svalbard archipelago (wiig 1995; mauritzen et al. 2001). polar bears are generally found in low densities throughout the arctic, but can also concentrate close to or on land during parts of the year. this can occur during maternity denning in winter, for example, in kong karls land, norway (larsen 1986), or during summer and autumn, when they are stranded until the sea ice freezes, for example, in hudson bay, canada (derocher & stirling 1990). polar research 2016. # 2016 m. andersen & j. aars. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 the first to describe the population biology of polar bears in norway, lønø (1970) analysed all available data on polar bear hunting in svalbard up to a few years before protection of the population was enacted. his work documented the very high take of polar bears in this region from about 1870 to 1970. between 100 and 900 bears were shot annually in northern greenland and the barents sea region during this period. it soon became apparent that the population was in danger of being extirpated if the harvest was allowed to continue with only limited controls (anonymous 1966). the same situation was seen in other arctic regions, spurring international action to protect polar bears (prestrud & stirling 1994). initiatives among the polar bear nations*canada, denmark (now greenland), norway, the soviet union (now russia) and the usa*which were facilitated by the iucn, resulted in the signing of the agreement on the conservation of polar bears (hereafter called the agreement) in 1973 (www.pbsg.npolar.no/en/agree ments/agreement1973.html). article ii of the agreement states that: . . . each contracting party shall take appropriate action to protect the ecosystems of which polar bears are a part, with special attention to habitat components such as denning and feeding sites and migration patterns, and shall manage polar bear populations in accordance with sound conservation practices based on the best available scientific data. article vii states that to achieve this goal: . . . the contracting parties shall conduct national research programmes on polar bears, particularly research relating to the conservation and management of the species. they shall as appropriate coordinate such research with research carried out by other parties, consult with other parties on the management of migrating polar bear populations, and exchange information on research and management programmes, research results and data on bears taken. during the period between the first meeting among polar bear nations in 1965 and the signing of the agreement, the negotiating parties established the iucn/ssc polar bear specialist group, which provided the scientific basis for the agreement. the polar bear specialist group has managed the agreement and guided national authorities in their management of polar bears, and since 2009 it has served as an independent advisor to the parties of the agreement. polar bears have now been included in the bern convention on the conservation of european wildlife and natural habitats and the convention on international trade in endangered species of wild fauna and flora. in norway, the svalbard environmental protection act includes several regulations to protect polar bears and their habitat. the norwegian ministry of climate and environment, which is responsible for nature conservation and management in norway, has ambitious goals for the management of svalbard and its wildlife. status of polar bears and population threats are therefore specifically dealt with in the management plan for lofoten and the barents sea (anonymous 2010), which was presented to the norwegian parliament in march 2006 and revised in 2010. the first report of the intergovernmental panel on climate change to mention the consequences of climate change for sea-ice cover in the arctic was the third assessment (houghton et al. 2001). based on this report, the iucn asked the polar bear specialist group for a new evaluation of the international red list status of polar bears, leading to a classification change from near threatened to vulnerable in 2006. as part of the work with the national evaluation in the usa, under the endangered species act, the us fish and wildlife service called for a meeting in 2007. polar bear authorities from all polar bear nations, known as range states, were invited to exchange information about polar bear research and management and to discuss the status of populations and measures to conserve the species. it was agreed that a meeting of the parties to the polar bear agreement of 1973 should be held biannually. during the meetings in 2009 and 2011, the main goal was to develop a range-wide action plan for polar bears, and this work was finalized in september 2015 (polar bear range states 2015). these initiatives came as a response to concerns that had been raised about climate change effects on polar bears. global warming (comiso 2002; core writing team et al. 2007; comiso et al. 2008) is believed to represent a threat to polar bear populations throughout their range on account of the declining area, connectivity (sahanatien & derocher 2012) and suitability of sea-ice habitats for bears (stirling & derocher 1993; derocher et al. 2004; amstrup et al. 2008; wiig et al. 2008; durner et al. 2009; abbreviations in this article coy: cub of the year gps: global positioning system iucn: international union for the conservation of nature mosj: environmental monitoring of svalbard and jan mayen npi: norwegian polar institute pcb: polychlorinated biphenyl ssc: species survival commission barents sea polar bears m. andersen & j. aars 2 (page number not for citation purpose) citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 http://pbsg.npolar.no/en/agreements/agreement1973.html http://pbsg.npolar.no/en/agreements/agreement1973.html http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 molnár et al. 2010; molnár et al. 2011). the decrease in habitat for polar bears and their main prey, ringed seals (pusa hispida), may lead to a reduction in population sizes and possibly to complete loss of some populations (amstrup et al. 2008; durner et al. 2009; amstrup et al. 2010; molnár et al. 2010). the barents sea population has been identified as one of the populations where predicted reductions in sea ice in coming decades are particularly severe (durner et al. 2009). in 2010, under the auspices of the arctic council working group conservation of arctic flora and fauna, an initiative was taken to develop a circumpolar monitoring plan for polar bears. a background paper was presented at the working group’s biennial meeting in february 2011 (vongraven & peacock 2011), and a circumpolar monitoring framework has been developed (vongraven et al. 2012). this framework identifies several threats and stressors to polar bear populations, identifies recommended monitoring parameters and knowledge gaps and suggests how to fill these gaps and improve monitoring. the conclusions are in agreement with threats previously identified for the barents sea population in a plan designed to monitor svalbard and jan mayen (sander et al. 2005), but argue that a more comprehensive monitoring programme is needed on a circumpolar level to coordinate monitoring activities, utilize monitoring capacities in a more efficient manner and facilitate monitoring that feeds into an adaptive management regime. the framework presented by vongraven et al. (2012) uses the ecoregion classification concept, outlined in amstrup et al. (2008). polar bear populations throughout the arctic are categorized according to the characteristics and predicted changes in the sea-ice habitat (divergent, convergent, archipelago and seasonal sea ice). vongraven et al. (2012) recommend that high-intensity monitoring should be conducted in at least six of the 19 polar bear populations throughout the arctic; the barents sea is one of the suggested areas. the barents sea population is chosen as a representative of a divergent sea-ice ecoregion (amstrup et al. 2008) because baseline data are available, there is a high risk of climate change effects and high contaminant levels are likewise documented. the first polar bear was live-captured and tagged as part of the norwegian polar bear research programme in 1966 (larsen 1967, 1970), initiating a new era in polar bear research and management in the region. in the years following, a range of population studies was conducted (e.g., harington 1965; lentfer 1969; jonkel 1970; larsen 1972). in 1975, concern was raised for the first time regarding high levels of pollutants found in polar bear tissues (bowes & jonkel 1975). contaminants continue to be a significant threat to polar bear health (letcher et al. 2010; obbard et al. 2010; sonne 2010; dietz, basu et al. 2013; dietz, rigét et al. 2013) and recent findings regarding effects on immune responses and metabolism highlight the complexity of this issue (braathen et al. 2004; lie et al. 2004, 2005; villanger et al. 2011). today, polar bears are included in several monitoring programmes because they are seen as indicators of the environmental condition of the arctic and because of international obligations: mosj (sander et al. 2005), arctic monitoring and assessment program (nilsson & huntington 2009) and conservation of arctic flora and fauna (vongraven & peacock 2011; vongraven et al. 2012). since the legal protection of polar bears in svalbard was enacted in 1973, the npi has been responsible for norway’s polar bear research and monitoring programme. the main aim of the programme has been to supply knowledge needed by management authorities. while maintaining its long-term perspective, the programme has adapted to answer new questions as they have arisen. the main focus of the npi programme was initially to study the effect the century-long period of hunting had had on the population, but later pollution, anthropogenic activity and tourism and, most recently, climate change have been prioritized issues. in the following review, we describe key aspects of polar bear population biology in svalbard and the broader barents sea region after hunting stopped in 1973. further, we explore potential impacts of new threats such as seaice change, human disturbance and pollution on polar bears, while also considering ecosystem effects. findings in the literature are discussed in relation to future management and monitoring of polar bears in the region. population biology and linkages to threats population history the barents sea polar bear population is shared between norway and russia (mauritzen et al. 2002) and has been protected against hunting since 1956 in russia and 1973 in norway (prestrud & stirling 1994). capture�recapture and satellite telemetry data reveal that the population is distributed from svalbard in the west and franz josef land in the east. in between these land masses, polar bears are found in the ice-covered parts of the barents sea and the arctic ocean (wiig 1995; mauritzen et al. 2002; fig. 1). larsen (1986) suggested that there were between 3000 and 6700 polar bears (depending on the population borders) in the barents sea at the beginning of the 1980s. this was based on data from multiple sources, including den counts and spatially restricted non-random m. andersen & j. aars barents sea polar bears citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 aerial surveys, which were extrapolated to larger areas. no study covering the whole area in question had been undertaken prior to the survey conducted in 2004 (aars et al. 2009). most population estimates for polar bears have been derived using capture�recapture methods (e.g., demaster et al. 1980; taylor et al. 2005). obtaining sufficiently large sample sizes is time consuming and expensive (wiig & derocher 1999), but the method yields valuable data on individuals for a range of other population ecology studies. recent statistical developments have made distance sampling one of the most widely used methods for estimating animal abundance in the last decade (buckland et al. 2004) and it is today regarded as being more cost efficient than capture�recapture to achieve high levels of precision (borchers et al. 2002), in particular for populations occurring at low densities over large areas. aars et al. (2009) concluded that the barents sea population had approximately 2650 (95% confidence interval approximately 1900�3600) bears in august 2004. they found significant geographic variability in densities of bears across different types of habitats in the study area. the density of bears on land-fast ice and pack ice in the russian areas to the east was much higher (�2 bears/ 100 km 2 ) than in the norwegian territory (0.4�1 bears/ 100 km 2 ). the mean density of polar bears across the whole region was, however, close to the densities described elsewhere in the arctic (taylor & lee 1995; evans et al. 2003). polar bear spatial patterns are known to vary with both season and year. individual polar bears in the barents sea show high seasonal fidelity to specific areas (mauritzen et al. 2001). many of the polar bears that are distributed around the islands of svalbard in spring are distributed along the ice edge further northeast in the russian area and around franz josef land in august. during the survey in 2004 there were three times as many bears in the russian parts of the northern barents sea compared to the norwegian area (aars et al. 2009). both the number of maternity dens (larsen 1986; andersen et al. 2012) and the relatively high number of recaptures of bears in the svalbard area (derocher 2005) indicate that more polar bears are present in the svalbard area in spring compared to other times of the year. this is partly explained by the need for pregnant females to find suitable denning habitat on land and raise cubs in a stable ice habitat in spring. bears may also be attracted by the generally good breeding habitat for ringed and bearded seals (erignathus barbatus) in svalbard fjords and the resulting good spring hunting habitat for the polar bears, particularly on the east coast (derocher et al. 2002; andersen et al. 2012; freitas et al. 2012). how the significant changes in the sea-ice habitat recently taking place in the barents sea may affect the fig. 1 the barents sea and surrounding land areas. the barents sea polar bear population is distributed from svalbard in the west to franz josef land in the east. the majority of the polar bears in the population is found in sea-ice covered areas between, and north of, these archipelagos. barents sea polar bears m. andersen & j. aars 4 (page number not for citation purpose) citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 polar bear population in the long run is unknown. a possible scenario, based on what we know about space use strategies, is a stronger separation between pack-ice bears and those that use habitat closer to and on land. if this unfolds, population boundaries and definitions may have to be re-evaluated. harvest history the initial threat to polar bears in the region was unquestionably overharvest. bear numbers were reduced quite drastically between 1909 and 1970 when an average of 320 polar bears were harvested annually in svalbard and adjacent areas (lønø 1970). assuming an even sex ratio in the harvest, the sustainable take of a closed polar bear population under optimal conditions is considered to be 3.2% (taylor et al. 1987). this implies that the barents sea population should have numbered at least 10 000 polar bears to have sustained the recorded harvest. the harvest obviously was not sustainable, but the calculation still indicates that the historical population size must have been significantly higher than the current size. the large difference between this number and the upper confidence limit (3600) of our estimate in 2004, after 40 years of protection, is noteworthy. larsen (1986) indicated that the population approximately doubled in size over a decade after protection in 1973 and suggested that there were close to 2000 bears in the svalbard area and 3000�6700 in the area between east greenland and franz josef land in 1980. the growth rate from then and up to 2004 is unknown. changes in population age structure suggest that population growth has been positive, but also that the growth rate today is much lower than earlier (derocher 2005). one possible explanation for the large difference in the estimated size in 2004 and the theoretical historical size (10 000) could that the latter was expanded by significant immigration from less hunted neighbouring areas. however, the discrepancy between the recent estimate and the historical harvest levels is so significant that it is not likely that migration alone can explain the difference. aars et al. (2009) speculate that either the population size today is far from the carrying capacity of the region or the carrying capacity has changed. derocher et al. (2003) and derocher (2005) suggested that the population recovery may have been slow after protection because high levels of organic pollutants (e.g., andersen et al. 2001) in polar bears in the region have had a negative effect on survival and reproductive rates (derocher 2005). the time needed for the population to recover to its carrying capacity could therefore be longer than suggested by demographic rates typical for other, less polluted, populations. the carrying capacity in the area may also have decreased during the last few decades and may continue to decrease in the future as a response to sea-ice loss (derocher 2005; heggberget et al. 2006; durner et al. 2009; wiig et al. 2015). space use and sea-ice change it is believed that polar bear habitat in svalbard and the barents sea will be significantly reduced during the coming decades and it has been suggested that the population will decrease as a consequence (amstrup et al. 2008; durner et al. 2009; amstrup et al. 2010). the main reason is the loss of the platform needed for hunting ice-associated prey (stirling & archibald 1977; smith 1980; derocher et al. 2002; thiemann et al. 2008). sea ice is also a platform for mating and travelling to and from terrestrial maternity denning areas (wiig et al. 2008; derocher et al. 2011). evidence of decline in polar bear body condition, reproductive success, survival and abundance has been documented in the canadian arctic and the beaufort sea in alaska, and the decline is thought to be caused by nutritional limitations imposed by diminishing sea ice (stirling et al. 1999; regehr et al. 2007; regehr et al. 2010; rode et al. 2010; stirling & derocher 2012). in svalbard, lowered body condition in the year after a bad ice year has been seen in male polar bears (mosj: www.mosj.npolar.no/en/fauna/marine/in dicators/polar-bear.html). to make reliable predictions about the future impacts of climate change on polar bears, it is essential to describe habitat use and identify especially important habitats. the use of satellite telemetry in the study of polar bear movement and distribution was first applied between svalbard, norway and greenland in 1979, when polar bears were equipped with satellite transmitters (larsen et al. 1983). one of the latest technological developments for studies of wildlife has been to use gps to determine the location of animals (e.g., johnson et al. 2002; frair et al. 2004; gau et al. 2004; morales et al. 2004), and to use the argos system to collect these data from the transmitters remotely (e.g., yasuda & arai 2005; parks et al. 2006; andersen et al. 2008). gps collar technology gives the opportunity to explore polar bear habitat use on a fine scale (freitas et al. 2012). previous studies have shown that polar bear distribution is significantly affected by sea-ice concentration and sea-ice type. polar bears typically select ice concentrations ranging from 25 to 100%, depending on the season and the region (stirling et al. 1993; arthur et al. 1996; ferguson, taylor & messier 2000; ferguson et al. 2001; mauritzen et al. 2003; durner et al. 2009). in the canadian arctic, m. andersen & j. aars barents sea polar bears citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 5 (page number not for citation purpose) http://mosj.npolar.no/en/fauna/marine/indicators/polar-bear.html http://mosj.npolar.no/en/fauna/marine/indicators/polar-bear.html http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 females with coys select land-fast ice with pressure ridges during the spring, while lone adult females and males show strong preferences for ice-edge areas (stirling et al. 1993). females with coys were thought to select landfast ice habitats to feed on ringed seal pups and also to avoid adult males, which are rare in this habitat; male bears sometimes prey on cubs (stirling et al. 1993). in svalbard and the barents sea area, female polar bears with coys also show a year-round tendency to be located on more solid ice than lone adult females (mauritzen et al. 2003). freitas et al. 2012 found that female polar bears with coys predominantly occupied inshore land-fast ice areas during spring (april), and within this habitat they spent most time close to glacier fronts. in an aerial, survey study in the canadian arctic, stirling et al. (1993) also reported that females with coys showed a strong preference for land-fast ice during spring. however, in svalbard they concentrated their time in land-fast ice close to glacier fronts while in the canadian arctic they selected fast-ice with snow drifts along pressure ridges, which were sometimes located far offshore. these preferred areas, in the respective locations, are linked to ringed seal pupping habitat. ringed seals give birth during spring inside lairs that are constructed in snow that accumulates in stable sea-ice areas (smith & stirling 1975; kingsley et al. 1985; furgal et al. 1996). nutritionally stressed polar bear females with coys need a predictable food source when emerging from their maternity dens in spring so these ringed seal pupping areas are a vital resource. in such areas, the female bears hunt ringed seal pups and sometimes their mothers (stirling & mcewan 1975; pilfold et al. 2012; c. lydersen, pers. comm.) without having to move long distances. accordingly, most females with coys in the study by freitas et al. (2012) spent their entire tracking period/ spring in the land-fast ice habitats, close to known denning areas (andersen et al. 2012). ringed seals occur in high densities in land-fast ice areas (krafft et al. 2007) during april and bearded seals and harp seals (pagophilus groenlandicus) also occur in the pack ice close to shore around svalbard during spring (haug et al. 1994; isaksen & wiig 1995). all of these species have been recorded in the diet of polar bears from this area (lønø 1970; derocher et al. 2002; iversen et al. 2013). even if seal density is lower in the pack ice, bearded and harp seals are larger prey and represent a larger energy package for polar bears than ringed seals. female polar bears in svalbard may face a trade-off between exploiting land-fast ice that provides a safe substrate for cubs as well as a predictable and relatively high-density supply of small prey items and exploiting less stable drift ice, where prey are larger but their availability is more unpredictable and they occur at lower densities. the study by freitas et al. (2012) clearly emphasizes the importance of coastal fast-ice, in particular close to glacier fronts, for polar bear females with young cubs in svalbard. reductions in the extent of land-fast ice have been observed in recent years in svalbard (haarpainter et al. 2001; gerland & hall 2006; gerland et al. 2007; høyland 2009). glacier fronts that calve into the ocean, churning up nutrients and attracting wildlife, have also retreated inland in svalbard in recent years (blaszczyk et al. 2009). the eventual disappearance of these preyrich and stable sea-ice habitats close to the preferred denning habitat where polar bear with coys concentrate during spring is likely to alter present distribution and hunting patterns and ultimately also reduce the reproductive rate of females and survival of cubs. den distribution in svalbard the use of maternity dens in snow is a characteristic adaptation in polar bears to the harsh arctic environment (blix & lentfer 1979). polar bears typically den at low densities throughout the circumpolar arctic, but concentrated denning areas exist at wrangel island, russia (belikov 1980), kong karls land, svalbard (larsen 1985), and south-west hudson bay, canada (jonkel et al. 1972). most maternity dens are located on land, although a few are made in multi-year sea ice off the alaskan coast (harington 1968; lentfer 1975; amstrup & gardner 1994; fischbach et al. 2007). in hudson bay, polar bears den in earth dens that can be up to 80 km from the coast, but bears move into snow dens as snow accumulates in autumn (jonkel et al. 1972; richardson et al. 2005). denning philopatry among female polar bears has been shown in hudson bay (ramsay & stirling 1990), in svalbard (zeyl et al. 2010) and the beaufort sea (amstrup & gardner 1994). andersen et al. (2012) found that most maternity dens in svalbard are close to the coast (b10 km). denning occurs in most parts of svalbard, but the number of dens seems to be highest in the eastern parts of the archipelago (fig. 2). the six most important denning areas are: (1) north-western spitsbergen, (2) southern spitsbergen, (3) northern parts of nordaustlandet, (4) barentsøya and edgeøya, (5) kong karls land and (6) hopen (fig. 2). the scarce data available indicate that polar bears captured in svalbard or in the central parts of the barents sea also den in the franz josef land archipelago, as noted by wiig (1998). lønø (1970) suggested that denning in svalbard was restricted to the eastern parts, including kong karls land, barents sea polar bears m. andersen & j. aars 6 (page number not for citation purpose) citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 nordaustlandet and along the northern part of the east coast of spitsbergen. larsen (1985) concluded that kong karls land was the main denning area and that 90% of all dens in the archipelago were on the islands edgeøya, barentsøya, nordaustlandet and kong karls land. the small island hopen was not considered an important denning site by lønø (1970) or larsen (1985), because only a few observations of dens or females with coys had been made there. we believe that denning distribution in svalbard is currently wider than it was in the decades before protection from hunting in 1973. we suggest that this apparent expansion is a result of re-establishment of denning areas after a long period of harvest. fidelity to denning areas by female polar bears (ramsay & stirling 1990; zeyl et al. 2010) might have delayed re-establishment associated with the population recovery. factors determining the distribution of polar bear dens are poorly understood, but in svalbard some areas can only be used for denning if sea ice reaches them in autumn, making them accessible (derocher et al. 2011). the linkage between denning and sea-ice conditions has also been described by others (ferguson, taylor, rosing-asvid et al. 2000). early snow cover is also necessary in most areas, and the terrain is important for snow accumulation. in the beaufort sea, about half of the dens were on drifting pack ice, half on land and some few on land-fast ice (amstrup & gardner 1994). there has been no evidence of offshore denning in svalbard (lønø 1970; larsen 1986), and the highly dynamic sea-ice conditions in the region may explain why this behaviour is not seen. the findings of andersen et al. (2012) indicate that most denning areas in svalbard are close to fast-ice areas where ringed seals give birth to their pups. this agrees well with the finding of freitas et al. (2012) that in april females with coys use land-fast ice areas and single females or females with older cubs use other habitat types more frequently. effect of historical harvest on denning human activities can influence polar bear denning distribution (lentfer & hensel 1980; stirling & andriashek 1992; amstrup 1993). much of svalbard’s long history of polar bear harvesting involved the very effective but nonselective use of set-guns*baited guns, typically built into wooden boxes. females emerging from dens with coys were particularly vulnerable (lønø 1970). larsen (1985) argued that denning in the edgeøya region had been heavily affected by more than 70 years of hunting, fig. 2 distribution of polar bear dens recorded in the svalbard area (n �534) during ground and aerial surveys, accumulated from 1972 to 2010. (from andersen et al. 2012). m. andersen & j. aars barents sea polar bears citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 and that after 10 years of protection the area was again used frequently for denning. the same could be the case for hornsund in the south and the fjords in the north of spitsbergen, because both of these areas also experienced high hunting pressure during the decades before protection in 1973. trappers and station personnel hunted bears on hopen from the early 1900s onwards (lønø 1970). during the early to mid-1900s only two dens were recorded on hopen (lønø 1970). the reason for the larger number of dens on the island during the years 1995�2008 (derocher et al. 2011) compared to the earlier period, when sea ice was likely more suitable for denning, is unknown, but it may be related to the difference in the number of adult females in the population. between 1945 and 1970, an average of 41 bears per year was harvested at hopen and from 1946 to 1968 altogether 951 bears were hunted there (lønø 1970). the population was thought to have been depleted before hunting ended in 1973 (larsen 1986; prestrud & stirling 1994) and protection allowed the population to recover over the next 30 years (derocher 2005). the larger number of maternity dens observed in later years may be a result of the reestablishment of hopen as a denning area as the population increased (aars et al. 2009; derocher et al. 2011). sea-ice change and denning andersen et al. (2012) and freitas et al. (2012) describe den distribution and female habitat use just after den emergence in spring, respectively. sea ice is also a critical habitat for female polar bears in autumn, when they prepare to enter their winter birthing dens (derocher et al. 2011). the timing of sea-ice formation and melt near hopen has varied substantially over time, reflecting its location near the southern edge of sea-ice extent in the barents sea (shapiro et al. 2003). a trend towards later arrival of sea ice has been observed at hopen, coinciding with a reduction in sea-ice thickness observed over the last four decades (gerland et al. 2008). the arrival of sea ice at hopen shifted from late october to mid-december during the period from 1979 to 2010. derocher et al. (2011) showed that fewer maternity dens were found on hopen in years when sea ice arrived later in the autumn. if sea ice formed too late, no dens were found. further, later arrival of sea ice in autumn was correlated with lower body mass of adult females and their cubs at den emergence in the spring, suggesting that recent environmental conditions have negatively affected female condition. body mass is an indication of energy stores (molnár et al. 2009) that are critical for supporting female polar bears during the denning period, when energy is required for maternal maintenance, gestation and nursing (watts & hansen 1987; derocher et al. 1993; molnár et al. 2011). maternal body mass in spring has been positively correlated with body mass of cubs and with cub survival (derocher & stirling 1996, 1998). the finding that cub mass was lower when the date of arrival of sea ice was later (derocher et al. 2011) suggests that the timing of the arrival of pregnant females at den areas may impact reproductive success. after leaving the den, young polar bear cubs are vulnerable to hypothermia if exposed to cold water (blix & lentfer 1979; aars & plumb 2010). the suitability of a maternity denning area for raising cubs is determined in part by the timing of sea-ice arrival and departure as well as the sea ice type and its stability (freitas et al. 2012). there is reason to believe that the fast-ice habitat has deteriorated around hopen in recent years, an effect of the generally lower sea-ice concentration and thickness in the area. the reproductive success of females that manage to den on hopen could be negatively affected if the sea ice departs earlier in spring in the future. the loss of one maternity denning area may not be a major cause for concern because females are able to den in other areas. however, the loss of habitat is symptomatic of larger ecosystem changes that cumulatively may threaten the persistence of polar bears (amstrup et al. 2010; hunter et al. 2010; molnár et al. 2010; molnár et al. 2011). further, the hopen situation might reflect the situation at other important denning areas in svalbard where autumn sea ice is necessary for giving pregnant females access to denning habitat (npi, unpubl. data). monitoring maternity denning areas at the margin of the polar bear range will be important to better understand how adult female polar bears, and ultimately the species, will respond as sea-ice patterns change. anthropogenic disturbance in svalbard although polar bears are no longer harvested in norway they are still vulnerable to human impacts (lunn et al. 2002). recreational activities, such as tourism and camping, are the source of most polar bear�human encounters in svalbard. tourism and the local use of snowmobiles have increased in svalbard over the last 40 years (overrein 2002; mosj: www.mosj.no/en/influ ence/traffic/snowmobiles.html). to avoid the mountainous terrain, much snowmobile driving in svalbard occurs on land-fast sea ice. on the ice, polar bears hunt ringed seals (derocher et al. 2002), and the stable fast-ice habitat is particularly important for females with coys (freitas et al. 2012). the sea ice is also a substrate for movement between hunting habitats and denning areas (mauritzen 2002; derocher et al. 2011; andersen et al. 2012; freitas et al. 2012). barents sea polar bears m. andersen & j. aars 8 (page number not for citation purpose) citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 http://www.mosj.no/en/influence/traffic/snowmobiles.html http://www.mosj.no/en/influence/traffic/snowmobiles.html http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 increasing human activity in the arctic makes it important to better understand human disturbance of wildlife in the region. since studies of disturbance are rarely able to assess effects on survival or reproductive success or other effects at the population level, we will most likely have to depend on studies of effects on behaviour and physiological responses as indicators. such studies can be valuable if the biology of the species is well understood and one can make plausible interpretations about how these responses link to demographic processes. another limitation apparent in many disturbance studies is that the effect measured on an individual has a short duration. cumulative population level effects are difficult to assess in most wild populations, and particularly in a long-lived and highly mobile species such as the polar bear. polar bears are highly mobile at large temporal and spatial scales, but when considering small-scale movement behaviour within a limited period of time (such as within a fjord) polar bear movements may be restricted (andersen et al. 2008; freitas et al. 2012). stirling (1974) found that polar bears on the sea ice at devon island, canada, spent most of their time inactive. andersen & aars (2008) observed polar bears running at least one km (and up to 5 km) when disturbed by snowmobiles, and several bears left the ringed seal breathing holes where they were hunting when vehicles approached. females with coys in particular showed strong reactions to this kind of disturbance. we believe that repeated disturbance in this important fast-ice habitat could result in increased energetic stress on the animals during a time when they are rebuilding energy stores that are critical for cub survival. additionally, polar bears are not adapted to running quickly over extended distances and large individuals in particular overheat rapidly if pursued for long (øritsland 1970). such stress could force polar bears to use sub-optimal habitats and spend more time in the water, where they typically take refuge when started. it could also lead to more frequently interrupted hunting situations or suckling/feeding bouts, which could affect body condition and growth of both adults and cubs/ coys. tourism and associated disturbance is a potential stressor that can act on a local spatial scale during short periods of the year. local planning and regulations could significantly reduce the negative effects of tourism if relevant and sufficient knowledge of polar bear ecology is available. in svalbard, regulations limiting snowmobile traffic in sensitive areas in springtime reduce disturbance of females with cubs that have just emerged from their dens (andersen & aars 2008). increased human presence in the arctic in general and in svalbard and the barents sea specifically may lead to more human�bear conflicts, jeopardizing both bears and people. in several incidents in recent years, campers in polar bear territory have been forced to kill polar bears. as the arctic becomes an increasingly attractive and less remote place to visit, and skiing and hiking expeditions grow in popularity, local regulations and knowledge are needed to keep polar bears and humans safe. polar bear diet in the barents sea in the first study of polar bear diet in svalbard, the remains of 52 ringed seals, 10 bearded seals and six harp seals were found in the stomachs of harvested bears (lønø 1970). harp seals were only found during summer (june� august) and most bearded seals (9/10) were found in the same period. these findings were similar to the composition of the 114 samples of known prey species found by derocher et al. (2002): 76% ringed seal, 15% bearded seal and 9% harp seal. similar to earlier studies, ringed seals are the dominant prey of polar bears numerically. however, results obtained by lønø (1970) and derocher et al. (2002) suggest that bearded seals, which are larger than ringed seals, make a significant contribution in terms of biomass to the diet of polar bears in svalbard and the western barents sea (andersen et al. 1999). in the eastern barents sea, a russian study reported 68% ringed seal, 22% walrus (odobenus rosmarus) and other miscellaneous items in the diet of polar bears (parovshchikov 1964), perhaps reflecting further geographic variation in the same population. most information on polar bear diet from the barents sea is from spring, but iversen et al. (2013) reported findings based on scat samples from both spring and summer. their study showed that polar bears in svalbard feed on eggs, reindeer (rangifer tarandus) and vegetation, in addition to seals. reindeer predation by svalbard polar bears was also documented by derocher et al. (2000), and hedberg et al. (2011) found fatty acids in polar bear milk that indicated that they had fed on reindeer. the distribution and abundance of marine mammal resources available to polar bears in svalbard are only partially described. bearded seals are widely distributed throughout svalbard and the western barents sea (benjaminsen 1973). their abundance is uncertain but they may number a few hundred thousand in the north atlantic (burns 1981; kovacs et al. 2009). the size of the ringed seal population in the svalbard area is unknown but the global population likely numbers in the millions (reeves 1998; kovacs et al. 2009). in svalbard and the western barents sea, ringed seals give birth in both land-fast (smith & lydersen 1991) and drifting pack ice (wiig et al. 1999). freitas et al. (2012) showed that landfast ice is especially important for female polar bears with m. andersen & j. aars barents sea polar bears citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 coys on account of the combination of a stable substrate and the high density of ringed seal breeding lairs. the barents sea harp seal population is approximately 2.2 million animals (nilssen et al. 2000) and represents a seasonally abundant food source for polar bears. however, harp seals do not usually reach polar bear habitat until april�may and then increase in abundance along the drift ice edge until october, when they return south (haug et al. 1994; nordøy et al. 1998). the annual home range size of adult female polar bears in svalbard varies greatly, ranging from 185 km 2 to 373 539 km 2 (mauritzen et al. 2001) and dietary differences were postulated to explain the different space use patterns (mauritzen et al. 2001). in particular, mauritzen et al. (2001) suggested that near-shore bears relied more on the land-fast ice and preyed largely on ringed seals during spring, while pelagic bears preyed more on bearded and harp seals over a longer period. this is supported by research by freitas et al. (2012) and derocher et al. (2002), who found that ringed seal kills were most numerous in land-fast ice areas in spring and bearded and harp seal kills were mainly found in pack-ice areas in summer. feeding and contaminant exposure prey composition is an important element in understanding the ecotoxicology of polar bears. if climate change alters the distribution and abundance of prey (stirling & derocher 1993), documentation of the current predation patterns is essential for understanding how exposure to environmental pollutants might vary as a result of climate change (mckinney et al. 2009). working in hudson bay, mckinney et al. (2009) documented how changes in diet, following from changes in sea ice and prey availability, increased the levels of several contaminants in bear tissues. mckinney et al. (2011), mckinney et al. (2013) have also demonstrated how, in east greenland, polar bear contaminant exposure changed as an effect of dietary shifts. the release of contaminants into the environment started in europe from 1850 to 1930. a wide range of man-made pollutants, among them organochlorines, has since been transported by air and ocean currents from southern industrialized areas to the arctic, (oehme 1991; barrie et al. 1992; de march et al. 1998). these compounds are highly lipophilic and resistant to biological degradation; they accumulate in the marine environment and biomagnify up food chains (muir et al. 1988; barrie et al. 1992). arctic organisms are adapted to dealing with short periods of high production during which lipid energy stores are built up, resulting in high dependence on fat at most trophic levels (barrie et al. 1992). polar bears have the capacity to metabolize several organic pollutants (letcher et al. 2000), but the metabolites resulting from this process are believed to have an even more negative effect than the original compounds (cheek et al. 1999; marchesini et al. 2008; gutleb et al. 2010). pcb contamination pcbs were first identified in polar bears in the 1970s (bowes & jonkel 1975). svalbard polar bears have shown pcb levels comparable to those found in ringed seals from the baltic sea, where reproductive disorders were reported (norheim et al. 1992; olsson et al. 1992; bernhoft et al. 1997). in svalbard polar bears, a possible immunotoxic effect (bernhoft et al. 2000) and negative association between organochlorines and retinol and thyroid hormones have been reported (skaare et al. 2000). studies indicate that organic pollutants have a negative effect on immune response and metabolism in polar bears (lie et al. 2004, 2005; braathen et al. 2004; villanger et al. 2011). contaminants in polar bears have been studied in most parts of the species range (norstrom et al. 1998; verreault et al. 2005; muir et al. 2006; mckinney et al. 2011). however, limited data from most parts of the russian arctic have precluded an understanding of circumpolar pcb patterns. andersen et al. (2001) demonstrated regional variation in pcb contamination in polar bear blood between the european, russian and western north american arctic regions. they found pcb levels to be highest in the western part of the russian arctic, and that the relative contribution of the low-chlorinated congeners (pcbs with few chlorine atoms, less toxic) increases, while the higher chlorinated congeners (pcbs with higher number of chlorine atoms, more toxic) decrease, from west to east. different congener patterns between areas indicate that sources of pcb are different. the study showed that the proportion of the pcb congeners 118 and 156*the most acutely toxic congeners in this study*was higher in the chukchi sea compared to svalbard. andersen et al. (2001) suggested that the variation observed in their study is due to polar bears facing different pcb exposure between the regions, something that can be caused by heavier pollution in some areas compared to others, but also by differences in the food webs polar bears rely on. variation in levels and patterns of various pollutants found in polar bear tissue can be explained by regional prey differences or changes in the diet, as was demonstrated for hudson bay polar bears (mckinney et al. 2009). satellite tracking of individuals has shown that polar bears in the kara and laptev seas barents sea polar bears m. andersen & j. aars 10 (page number not for citation purpose) citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 spend considerable amounts of time in multi-year ice (belikov et al. 1998). this is also the case for parts of the population in svalbard and franz josef land (wiig 1995). regional differences in the structure of the ice-associated food webs may cause higher levels of contaminants high in the food web in one area compared to another. andersen et al. (2001) based their study on analyses of blood samples from polar bears captured in five different geographic regions. though all the bears were females captured in spring, there were differences in age, body condition and reproductive status at capture. females emerging from dens with young cubs are very lean (derocher & stirling 1998), while others who have lost their cubs or have older cubs start feeding earlier and may be in better condition. both longand short-term differences in feeding history (and therefore body condition) presumably influence the concentrations and patterns of organochlorines, which makes it difficult to draw conclusions from the analysis of blood samples, which reflect recent food intake (lydersen et al. 2002). in addition, females with offspring can shed pcbs through milk, also complicating interpretation of the results of contaminant analyses (bernhoft et al. 1997; polischuk 1999; bytingsvik et al. 2012). movement behaviour further complicates the issue. for example, olsen et al. (2003) explained differences in contaminant levels as a result of varying activity seen in small versus large home range sizes in barents sea polar bears. radionuclide contamination organic pollutants are accumulated in fatty tissues, whereas other groups of contaminants, such as radionuclides, use other pathways but nevertheless accumulate in top predators (in muscle and bone tissue), although less effectively than organic pollutants. the tendency for arctic marine food chains to depend on benthic and seaice associated systems provides an efficient mechanism for biomagnification of contaminants and, in combination with the longevity of marine mammals, this results in high uptake rates of radionuclides (e.g., pentreath et al. 1982; aarkrog et al. 1997; brown et al. 1999; carroll et al. 2002). the anthropogenic radionuclide caesium-137 ( 137 cs) makes its way into the arctic marine environment via global fall-out from atmospheric weapon testing, discharges from european reprocessing and power facilities and fall-out from the chernobyl accident in 1986. the low 137 cs levels observed in the marine mammals studied by andersen et al. (2006) reflect the low 137 cs activity in sea water in the european arctic following the reduction in discharges from reprocessing facilities at sellafield, uk, in the mid-1970s. recently reported 137 cs activities in sea water from the study area ranged from 2.0 to 3.4 bq/m 3 , compared to peak values of 20�45 bq/m3 for the svalbard area and barents sea in the 1980s (hallstadius et al. 1982; kershaw and baxter 1995; strand et al. 2002). numerous local sources of potential radionuclide contamination are known in the region, for example, nuclear reactor dump sites and atmospheric nuclear bomb testing sites on novaya zemlya. it appears from the data reported by andersen et al. (2006) that these potential sources have had little impact on marine mammals in the european arctic. in general, pollution acts across large temporal and spatial scales, potentially having negative effects on polar bear reproduction and survival in several populations. the decrease in pcbs found in arctic biota following the ban shows how positive results can be achieved (wolkers et al. 2008; dietz, rigét et al. 2013; rigét et al. 2013). however, relatively new compounds*for example brominated flame retardants and perfluoroalkyl contaminants* are being detected in polar bear tissues, calling for new research and management initiatives. while most sources of organic pollutants are found outside the arctic, and output is continuous but slow, there are many sources of radioactive contamination within the arctic, with the potential for acute and significant contamination. multiple stressors and future monitoring and management stressors and cumulative effects a stressor has been defined as a variable (biotic or abiotic) that adversely affects individual physiology or population performance and therefore has fitness consequences (barrett et al. 1976; vinebrooke et al. 2004). stressors can be both natural and anthropogenic, and they often interact to produce a combined impact. sea-ice changes, disturbance by people and pollution, are threats to polar bears in the svalbard and barents sea area that act on different spatial and temporal scales. consequently, they are linked to different aspects of polar bear population biology as stressors. jenssen pointed out that pollutants with endocrine-disruptive properties are the second most serious anthropogenic threat in the arctic, after climate change, and that the combination of these two stressors may be a ‘‘worst-case combination for arctic marine mammals and birds’’ (jenssen 2006: 79). dietz, basu et al. (2013) stated that different contaminants (for example, various pops and heavy metals) can act together, making it difficult to determine the effect of an individual compound in free-ranging animals. further, they noted that confounding factors such as m. andersen & j. aars barents sea polar bears citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 age, sex, reproductive status, body condition and diseases or other stressors further complicates analyses. they suggested nevertheless that increasing trends of mercury (hg) in polar bears from north-east canada and east greenland might represent a health risk to the most susceptible animals when stress from climate change, shifts in pathogen organisms, decreased access to food and other contaminants are simultaneously taken into account (dietz, basu et al. 2013). it has been documented that contaminants have negative effects on thyroid hormones, sex steroid homeostasis and the immune system of marine mammals, including polar bears (haave et al. 2003; olsen et al. 2003; oskam et al. 2003; braathen et al. 2004; lie et al. 2004, 2005; oskam et al. 2004; letcher et al. 2010). acting on quite different scales, sea-ice changes and human disturbance may reduce access to food or increase energy expenditure by making hunting less effective (including by reducing prey) or increasing the distances polar bears need to walk or swim. in combination with generally weaker health, the net effect of the stressors might affect survival significantly, especially for very young or old animals. this is suggested by a study in hudson bay, where a longer ice-free period lowered survival in these two age groups (regehr et al. 2007). the hudson bay population is not considered to be significantly impacted by pollution and disturbance by humans is limited to the period when bears are fasting on land. however, there is reason to believe that there will be an increase in disturbance and human�bear conflicts as climate change progresses, in this population and elsewhere in the arctic. lowered survival as a result of sea-ice changes was also found in polar bears in the southern beaufort sea (regehr et al. 2010). for svalbard, the effect of sea-ice reduction on survival has not yet been examined. however, contamination has been suggested as a possible explanation for the slow population recovery after the heavy harvest stopped in 1973 (derocher 2005). in addition, polar bear habitat in this region is projected to be significantly reduced in the decades to come, which will probably lead to decreasing population size (amstrup et al. 2008; durner et al. 2009; amstrup et al. 2010). during recent years in svalbard, ringed seal pup production, which takes place on both drift and land-fast ice (smith & lydersen 1991), has been very low in several important breeding fjords (kovacs et al. 2011). as the most nutritionally stressed group of bears in spring, female polar bears with small cubs will likely be particularly vulnerable to the loss of this potential prey (watts & hansen 1987; atkinson & ramsay 1995). since fat-soluble contaminants are released into blood circulation when stored fat is metabolized, high levels of contaminants are carried to the mothers’ vital organs during the period when the pregnant female is fasting in the den and during the first months of lactation, which causes transfer of pollutants first to the foetuses in utero and after birth to the cubs through the milk (polischuk et al. 2002). the negative effects of pollution and less sea-ice in the barents sea will act on polar bears synergistically if the combined effect is greater than one would expect by adding up the effects of the individual stressors (derocher 2005; jenssen 2006). although relatively little research has been conducted on the subject, it is expected that climate change may increase levels*and diversity*of pathogens in the arctic (bradley et al. 2005; burek et al. 2008), which would add another stressor to already struggling polar bears (derocher et al. 2004; molnár et al. 2010). baseline levels of occurrence of pathogens such as brucella, toxoplasma and viruses have been documented in polar bears from the svalbard area (tryland et al. 2001; tryland et al. 2005; oksanen et al. 2009; åsbakk et al. 2010; jensen et al. 2010), but long-term monitoring and the effects of disease in a multi-stressor analysis have not yet been established. monitoring and management the key feature of the recently introduced concept of adaptive monitoring is that the monitoring process should evolve as new knowledge and questions emerge (lindenmayer & likens 2009). this is exemplified by polar bear population monitoring. our knowledge about important impacts on this species has changed through time. recently, the need to better understand the population level effects of a range of stressors has been highlighted (vongraven & peacock 2011; vongraven et al. 2012). the barents sea polar bear population is monitored through mosj, which constantly evaluates the choice of monitoring parameters on the basis of findings produced by ongoing research. when research found that sea-ice conditions limited denning opportunities in a traditionally important denning area (derocher et al. 2011) monitoring of the sea-ice habitat surrounding the main denning areas was initiated. another example is the ongoing screening for new pollutants in polar bears in the region, which feeds into international processes to ban the release of certain industrial compounds. a corollary of adaptive monitoring is adaptive management (lindenmayer & likens 2009; vongraven et al. 2012): when changes occur in a population, management regimes should change accordingly. it is important to recognize that population changes might be rapid as barents sea polar bears m. andersen & j. aars 12 (page number not for citation purpose) citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 thresholds are crossed, and that plans for how to deal with such changes should be made early (derocher et al. 2013). management aims must be re-evaluated in light of new threats and information. for some subpopulations, sustainable harvest is the management goal; for others it is conservation of the species. maintaining that polar bears are not in danger of extinction, some stake-holders argue that powerful conservation measures, such as lowered quotas or total protection of animals and their habitats, are not needed and that good resource management is sufficient to ensure their survival (wiig 2005; vongraven 2009; vongraven et al. 2012). this may be true for some polar bear populations, but the status of others is far more uncertain. some populations are declining (regehr et al. 2007; hunter et al. 2010; regehr et al. 2010) and for others data is unavailable (obbard et al. 2010), indicating that a more careful conservation approach should be taken. the barents sea population is one of few populations that is totally protected and* within norwegian territorial waters*some habitat crucial for polar bears is under varying degrees of protection. in this population, the precautionary principle has been used as a conservation tool. as overharvesting and poaching were the main conservation concerns when the work on the polar bear agreement was initiated in the 1960s (anonymous 1966; prestrud & stirling 1994), quota systems were implemented for some populations and total protection for others (prestrud & stirling 1994). ongoing and future large-scale habitat losses, in combination with threats such as pollution and human development, are different kinds of challenges that require a broad management approach. while the rapid climate change of the last century is generally understood to be mainly anthropogenic (core writing team et al. 2007), the reversibility of climate change is being debated. amstrup et al. (2010) argued that a significant reduction in the emission of co2 to the atmosphere could slow the rate of sea-ice loss, benefitting polar bears. conservation it has been suggested that only strict conservation measures, requiring coordinated effort from all range states, will secure the survival of the species (vongraven & peacock 2011; vongraven et al. 2012). this is consistent with advice given to the international community with regard to conservation of mammals globally. rondinini et al. (2011) identified key elements for a successful largescale conservation strategy for mammals to include an institution with recognized authority, clear goals and objectives as well as relevant species data, a priority list and well developed indicators. proposing international cooperation around the convention on biological diversity as a possible starting point for a new global initiative for the conservation of mammals, rondinini et al. (2011) also suggest that an expanded version of the iucn red list would be a suitable future tool. wilson and co-workers point out that one of the main challenges in mammal conservation is prioritizing what to focus on, since ‘‘we cannot do everything, everywhere, all the time’’ (wilson et al. 2011: 2670). however, rondinini et al. (2011) stress the urgency of a global mammal conservation strategy in spite of significant knowledge gaps. recent international initiatives to improve knowledge and monitoring of polar bear populations throughout the range of the species (e.g., anonymous 2009; vongraven et al. 2012) are in line with these views. conclusions the biological traits that make polar bears well adapted to the arctic environment are problematic in the context of encounters with human activity, pollution and significant changes to sea-ice habitat. we have described how polar bears in svalbard have been negatively affected by human activity in the last century and how these threats have changed through time. the clear linkages between population biology and current anthropogenic threats give reason to believe that the combination of several stressors is having significant negative effects on polar bears. however, the processes involved and the population level effects are not well understood. an international action plan for polar bears was finalized in september 2015 (polar bear range states 2015) and a comprehensive monitoring programme that aims to give us an understanding of the consequences of multiple stressors has been recommended by an international expert group (vongraven et al. 2012). norway is obliged to manage the norwegian polar bears using the best available scientific data, as stated by article vii of the agreement, and should therefore follow the advice given by the group. norwegian authorities completed a national action plan for polar bears in 2013, addressing how the future management of the species requires relevant research and monitoring through increased scientific effort in the barents sea. the plan outlines the main areas of interest and concern in the barents sea population: the effects of habitat change, contamination, acute pollution and crisis handling, disturbance and stress due to human activities and human�bear conflicts. the plan also emphasizes norwegian responsibilities regarding cooperation with neighbouring countries and the international component of polar bear research and management. m. andersen & j. aars barents sea polar bears citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 13 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 acknowledgements we would like to thank øystein wiig, andrew e. derocher, dag vongraven, kit m. kovacs, erik w. born kristin laidre and two reviewers for valuable comments on an earlier version of this manuscript. we would also like to thank anders skoglund for creating the maps. references aarkrog a., baxter m.s., bettencourt a.o., bojanowski r., bologa a., charmasson s., cunha i., delfanti r., duran e., holm e., jeffree r., livingston h., mahapanyawong h., nies s., osvath i., pingyu l., povinec p., sanchez a., smith j. & swift d. 1997. a comparison of doses from 137 cs and 210 po in marine food: a major international study. journal of environmental radioactivity 34, 69�90. aars j., marques t.a., buckland s.t., andersen m., belikov s., boltunov a. & wiig ø. 2009. estimating the barents sea polar bear subpopulation size. marine mammal science 25, 35�52. aars j. & plumb a. 2010. polar bear cubs may reduce chilling from icy water by sitting on mother’s back. polar biology 33, 557�559. amstrup s.c. 1993. human disturbance of denning polar bears in alaska. arctic 46, 246�250. amstrup s.c., deweaver e.t., douglas d.c., marcot b.g., durner g.m., bitz c.m. & bailey d.a. 2010. greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence. nature 468, 955�958. amstrup s.c. & gardner c. 1994. polar bear maternity denning in the beaufort sea. journal of wildlife management 58, 1�10. amstrup s.c., marcot b.g. & douglas d.c. 2008. a bayesian network approach to forecasting the 21st century worldwide status of polar bears. in e.t. deweaver et al. (eds.): arctic sea ice decline: observations, projections, mechanisms, and implications. pp. 213�268. washington, dc: american geophysical union. andersen m. & aars j. 2008. short-term behavioural response of polar bears to disturbance by snowmobiles. polar biology 31, 501�507. andersen m., derocher a.e., wiig ø. & aars j. 2008. movements of two svalbard polar bears recorded using geographical positioning system satellite transmitters. polar biology 31, 905�911. andersen m., derocher a.e., wiig ø. & aars j. 2012. polar bear (ursus maritimus) maternity den distribution in svalbard, norway. polar biology 35, 499�508. andersen m., gwynn j.p., dowdall m. & lydersen c. 2006. radiocaesium in marine mammals from svalbard, the barents sea and the north greenland sea. science of the total environment 363, 87�94. andersen m., hjelset a.m., gjertz i., lydersen c. & gulliksen b. 1999. growth, age at sexual maturity and condition in bearded seals (erignathus barbatus) from svalbard, norway. polar biology 21, 179�186. andersen m., lie e., derocher a.e., belikov s.e., bernhoft a., boltunov a.n., garner g.w., skaare j.u. & wiig ø. 2001. geographic variation of pcb congeners in polar bears (ursus maritimus), from svalbard to the chukchi sea. polar biology 24, 231�238. anonymous 1966. proceedings of the first international scientific meeting on the polar bear at fairbanks, alaska. 6�10 september 1965. washington, dc: bureau of sport fisheries and wildlife, us department of the interior, and university of alaska. anonymous 2009. meeting of the parties to the 1973 agreement on the conservation of polar bears. 17�19 march 2009, tromsø, norway. outcome of meeting. accessed on the internet at http://pbsg.npolar.no/export/sites/pbsg/en/docs/outcome_ mop2009.pdf on 31 march 2016 anonymous 2010. meld. st. 10 (2010�2011). melding til stortinget. oppdatering av forvaltningsplanen for det marine miljø i barentshavet og havområdene utenfor lofoten. (meld. st. 10 [2010�2011]. report to the storting [white paper]. first update of the integrated management plan for the marine environment of the barents sea�lofoten area.) oslo: norwegian ministry of the environment. arthur s.m., manly b.f.j., mcdonald l.l. & garner g.w. 1996. assessing habitat selection when availability changes. ecology 77, 215�227. åsbakk k., aars j., derocher a.e., wiig ø., oksanen a., born e.w., dietz r., sonne c., godfroid j. & kapel c.m.o. 2010. serosurvey for trichinella in polar bears (ursus maritimus) from svalbard and the barents sea. veterinary parasitology 172, 256�263. atkinson s.n. & ramsay m.a. 1995. the effects of prolonged fasting on the body-composition and reproductive success of female polar bears (ursus maritimus). functional ecology 9, 559�567. barrett g.w., vandyne g.m. & odum e.p. 1976. stress ecology. bioscience 26, 192�194. barrie l.a., gregor d., hargrave b., lake r., sherer r., tracey b. & bidleman t. 1992. arctic contaminants: sources, occurrence and pathways. science of the total environment 122, 1�74. belikov s.e. 1980. distribution and structure of dens of female polar bears in wrangel island. bears. their biology and management 4, 117�118. belikov s.e., garner g.w., wiig ø., boltunov a.n. & gorbunov y.a. 1998. polar bears of the zevernaya zemlya archipelago of the russian arctic. ursus 10, 33�40. benjaminsen t. 1973. age determination and the growth and age distribution from cementum growth layers of bearded seals at svalbard. fiskeridirektoratets skrifter serie havundersøkelser 16, 159�170. bernhoft a., skaare j.u., wiig ø., derocher a.e. & larsen h.j.s. 2000. possible immunotoxic effects of organochlorines in polar bears (ursus maritimus) at svalbard. journal of toxicology and environmental health 59, 561�574. bernhoft a., wiig ø. & skaare j.u. 1997. organochlorines in polar bears (ursus maritimus) at svalbard. environmental pollution 95, 159�175. barents sea polar bears m. andersen & j. aars 14 (page number not for citation purpose) citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 http://pbsg.npolar.no/export/sites/pbsg/en/docs/outcome_mop2009.pdf http://pbsg.npolar.no/export/sites/pbsg/en/docs/outcome_mop2009.pdf http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 blaszczyk m., jania j.a. & hagen j.o. 2009. tidewater glaciers of svalbard: recent changes and estimates of calving fluxes. polish polar research 30, 85�142. blix a.s. & lentfer j.w. 1979. modes of thermal protection in polar bear cubs*at birth and on emergence from the den. american journal of physiology 236, 67�74. borchers d.l., buckland s.t. & zucchini w. 2002. estimating animal abundance. closed populations. london: springer. bowes g.w. & jonkel c.j. 1975. presence and distribution of polychlorinated biphenyls (pcb) in arctic and subarctic marine food chains. journal of the fisheries research board of canada 32, 281�286. braathen m., derocher a.e., wiig ø., sørmo e.g., lie e., skaare j.u. & jenssen b.m. 2004. relationships between pcbs and thyroid hormones and retinol in female and male polar bears. environmental health perspectives 112, 826�833. bradley m.j., kutz s.j., jenkins e. & o’hara t.m. 2005. the potential impact of climate change on infectious diseases of arctic fauna. international journal of circumpolar health 64, 468�477. brown j.e., kolstad a.k., brungot a.l., lind b., rudjord a.l., strand p. & føyn l. 1999. levels of 99 tc in seawater and biota samples from norwegian coastal waters and adjacent seas. marine pollution bulletin 38, 560�571. buckland s.t., anderson d.r., burnham k.p., laake j.l., borchers d.l. & thomas l. (eds.) 2004. advanced distance sampling. oxford: oxford university press. burek k.a., gulland f.m.d. & o’hara t.m. 2008. effects of climate change on arctic marine mammal health. ecological applications 18, 126�134. burns j.j. 1981. bearded seal erignathus barbatus erxleben, 1777. in s.h. ridgway & r.j. harrison (eds.): handbook of marine mammals. vol. 2. seals. pp. 145�170. london: academic press. bytingsvik j., lie e., aars j., derocher a.e., wiig ø. & jenssen b.m. 2012. pcbs and oh-pcbs in polar bear mother�cub pairs: a comparative study based on plasma levels in 1998 and 2008. science of the total environment 417, 117�128. carroll j., wolkers h., andersen m. & rissanen k. 2002. bioaccumulation of radiocaesium in arctic seals. marine pollution bulletin 44, 1366�1371. cheek a.o., kow k., chen j. & mclachlan j.a. 1999. potential mechanisms of thyroid disruption in humans: interaction of organochlorine compounds with thyroid receptor, transthyretin, and thyroid-binding globulin. environmental health perspectives 107, 273�278. comiso j.c. 2002. a rapidly declining perennial sea ice cover in the arctic. geophysical research letter 29, l1956, doi: 10.1029/2002gl015650. comiso j.c., parkinson c.l., gersten r. & stock l. 2008. accelerated decline in the arctic sea ice cover. geophysical research letter 35, l01703, doi: 10.1029/2007gl031972. core writing team, pachauri r.k. & reisinger a. (eds.) 2007. climate change 2007. synthesis report. contribution of working groups i, ii and iii to the fourth assessment report of the intergovernmental panel on climate change. geneva: intergovernmental panel on climate change. de march b.g.e., de wit c.a., muir c.g., braune b.m., gregor d.j., norstrom r.j., olsson m., skaare j.u. & stange k. 1998. persistent organic pollutants. in s.j. wilson et al. (eds.): amap assessment report: arctic pollution issues. pp. 183�371. oslo: arctic monitoring and assessment programme. demaster d.p., kingsley m.c.p. & stirling i. 1980. a multiple mark and recapture estimate applied to polar bears. canadian journal of zoology 58, 633�638. derocher a.e. 2005. population ecology of polar bears at svalbard, norway. population ecology 47, 267�275. derocher a.e., aars j., amstrup s.c., cutting a., lunn n.j., molnar p.k., obbard m.e., stirling i., thiemann g.w., vongraven d., wiig ø. & york g. 2013. rapid ecosystem change and polar bear conservation. conservation letters 6, 368�375. derocher a.e., andersen m., wiig ø., aars j., hansen e. & biuw m. 2011. sea ice and polar bear den ecology at hopen island, svalbard. marine ecology progress series 441, 273�279. derocher a.e., andriashek d. & arnould j.p.y. 1993. aspects of milk composition and lactation in polar bears. canadian journal of zoology 71, 561�567. derocher a.e., lunn n.j. & stirling i. 2004. polar bears in a warming climate. integrative and comparative biology 44, 163�176. derocher a.e. & stirling i. 1990. observations of aggregating behaviour in adult male polar bears (ursus maritimus). canadian journal of zoology 68, 1390�1394. derocher a.e. & stirling i. 1996. aspects of survival in juvenile polar bears. canadian journal of zoology 74, 1246�1252. derocher a.e. & stirling i. 1998. maternal investment and factors affecting offspring size in polar bears (ursus maritimus). journal of zoology 245, 253�260. derocher a.e., wiig ø. & andersen m. 2002. diet composition of polar bears in svalbard and the western barents sea. polar biology 25, 448�452. derocher a.e., wiig ø. & bangjord g. 2000. predation of svalbard reindeer by polar bears. polar biology 23, 675�678. derocher a.e., wolkers h., colborn t., schlabach m., larsen t.s. & wiig ø. 2003. contaminants in svalbard polar bear samples archived since 1967 and possible population level effects. science of the total environment 301, 163�174. dietz r., basu n., braune b., o’hara t., scheuhammer t., sonne c., andersen m., andreasen c., andriashek d., asmund g., aubail a., baagøe h., born e.w., chan h.m., derocher a.e., grandjean p., knott k., kirkegaard m., lunn n., messier f., obbard m., olsen m.t., peacock e., renzoni a., rigét f.f., skaare j.u., stern g., stirling i., taylor m., wiig ø., wilson s. & aars j. 2013. what are the toxicological effects of mercury in arctic biota? science of the total environment 443, 775�790. dietz r., rigét f.f., sonne c., born e.w., bechshøft t., mckinney m.a. & letcher r.j. 2013. three decades (1983� 2010) of contaminant trends in east greenland polar bears (ursus maritimus). part 1. legacy organochlorine contaminants. environment international 59, 485�493. m. andersen & j. aars barents sea polar bears citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 15 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 durner g.m., douglas d.c., nielson r.m., amstrup s.c., mcdonald t.l., stirling i., mauritzen m., born e.w., wiig ø., deweaver e., serreze m.c., belikov s.e., holland m.m., maslanik j., aars j., bailey d.a. & derocher a.e. 2009. predicting 21st century polar bear habitat distribution from global climate models. ecological monographs 79, 25�58. evans t.j., fischbach a., schliebe s., manly b., kalxdorff s. & york g. 2003. polar bear aerial surveys in the eastern chukchi sea: a pilot study. arctic 56, 359�366. ferguson s., taylor m., born e., rosing-asvid a. & messier f. 2001. activity and movement patterns of polar bears inhabiting consolidated versus active pack ice. arctic 54, 49�54. ferguson s., taylor m., rosing-asvid a., born e. & messier f. 2000. relationships between denning of polar bears and conditions of sea ice. journal of mammalogy 81, 1118�1127. ferguson s.h., taylor m.k. & messier f. 2000. influence of sea ice dynamics on habitat selection by polar bears. ecology 81, 761�772. fischbach a.s., amstrup s.c. & douglas d.c. 2007. landward and eastward shift of alaskan polar bear denning associated with recent sea ice changes. polar biology 30, 1395�1405. frair j.l., nielsen s.e., merrill e.h., lele s.r., boyce m.s., munro r.h.m., stenhouse g.b. & beyer h.l. 2004. removing gps collar bias in habitat selection studies. journal of applied ecology 41, 201�212. freitas c., kovacs k.m., andersen m., aars j., sandven s., mauritzen m., pavlova o. & lydersen c. 2012. importance of fast ice and glacier fronts for female polar bears and their cubs during spring in svalbard, norway. marine ecology progress series 447, 289�304. furgal c.m., innes s. & kovacs k.m. 1996. characteristics of ringed seal, phoca hispida, subnivean structures and breeding habitat and their effects on predation. canadian journal of zoology 74, 858�874. gau r.j., mulders r., ciarniello l.j., heard d.c., chetkiewicz c.b., boyce m., munro r., stenhouse g., chruszcz b., gibeau m.l., milakovic b. & parker k.l. 2004. uncontrolled field performance of televilt gps-simplex (tm) collars on grizzly bears in western and northern canada. wildlife society bulletin 32, 693�701. gerland s., gascard j.c., ivanov b., nielsen c.p., nilsen e., pavlova o., leu e., tverberg v. & barrault s. 2007. fast ice evolution in kongsfjorden compared with other svalbard fjords. extended abstract. in r. azzolini (ed.): 8th ny-ålesund seminar. 16�17 october 2007. cambridge, uk. polarnet technical report. pp. 44�46. rome: earth and environment department, national research council. gerland s. & hall r. 2006. variability of fast-ice thickness in spitsbergen fjords. annals of glaciology 44, 231�239. gerland s., renner a.h.h., godtliebsen f., divine d. & løyning t.b. 2008. decrease of sea ice thickness at hopen, barents sea, during 1966�2007. geophysical research letter 35, l06501, doi: 10.1029/2007gl032716. gutleb a.c., cenijn p., van velzen m., lie e., ropstad e., skaare j.u., malmberg t., bergman a., gabrielsen g.w. & legler j. 2010. in vitro assay shows that pcb metabolites completely saturate thyroid hormone transport capacity in blood of wild polar bears (ursus maritimus). environmental science & technology 44, 3149�3154. haarpaintner j., haugan p.m. & gascard j.c. 2001. interannual variability of the storfjorden (svalbard) ice cover and ice production observed by ers-2 sar. annals of glaciology 33, 430�436. haave m., ropstad e., derocher a.e., lie e., dahl e., wiig ø., skaare j.u. & jenssen b.m. 2003. polychlorinated biphenyls and reproductive hormones in female polar bears at svalbard. environmental health perspectives 111, 431�436. hallstadius l., holm e., persson b., aarkrog a. & nilsson k. 1982. 137 cs in the svalbard area. in: third international symposium. radiological protection*advances in theory and practice. proceedings. vol. 2. pp. 500�505. reading: society for radiological protection. harington c.r. 1965. the life and status of the polar bear. oryx 8, 169�176. harington c.r. 1968. denning habits of the polar bear (ursus maritimus phipps). canadian wildlife service report series 5, 1�30. haug t., nilssen k.t., øien n. & potelov v. 1994. seasonal distribution of harp seals (phoca groenlandica) in the barents sea. polar research 13, 163�172. hedberg g.e., derocher a.e., andersen m., rogers q.r., depeters e.j., lonnerdal b., mazzaro l., chesney r.w. & hollis b. 2011. milk composition in free-ranging polar bears (ursus maritimus) as a model for captive rearing milk formula. zoo biology 30, 550�565. heggberget t., bjørge a., swenson j.e., syvertsen p.o., wiig ø. & øien n. 2006. pattedyr. (mammalia.) in j.a. kålås et al. (eds.): norsk rødliste 2006. (2006 norwegian red list.) pp. 365�372. trondheim: artsdatabanken. houghton j.t., ding y., griggs d.j., noguer m., van der linden p.j., dai x., maskell k. & johnson c.a. (eds.) 2001. climate change 2001. the scientific basis. contribution of working group i to the third assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. høyland k.v. 2009. ice thickness, growth and salinity in van mijenfjorden, svalbard, norway. polar research 28, 339�352. hunter c.m., caswell h., runge m.c., regehr e.v., amstrup s.c. & stirling i. 2010. climate change threatens polar bear populations: a stochastic demographic analysis. ecology 91, 2883�2897. isaksen k. & wiig ø. 1995. seasonal distribution of harbour seals, bearded seals, white whales and polar bears in the barents sea. norsk polarinstitutt meddelelser 136, 47�59. iversen m., aars j., haug t., alsos i.g., lydersen c., bachmann l. & kovacs k.m. 2013. the diet of polar bears (ursus maritimus) from svalbard, norway, inferred from scat analysis. polar biology 36, 561�571. jenssen b.m. 2006. endocrine-disrupting chemicals and climate change: a worst-case combination for arctic marine mammals and birds? environmental health perspectives 114, 76�80. jensen s.k., aars j., lydersen c., kovacs k.m. & åsbakk k. 2010. the prevalence of toxoplasma gondii in polar bears and barents sea polar bears m. andersen & j. aars 16 (page number not for citation purpose) citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 their marine mammal prey: evidence for a marine transmission pathway? polar biology 33, 599�606. johnson c.j., heard d.c. & parker k.l. 2002. expectations and realities of gps animal location collars: results of three years in the field. wildlife biology 8, 153�159. jonkel c.j. 1970. some comments on polar bear management. biological conservation 2, 115�119. jonkel c.j., kolenosky g.b., robertson r. & russell r.h. 1972. further notes on the polar denning habits. international conference on bear research and management 2, 142�158. kershaw p.j. & baxter a. 1995. the transfer of reprocessing wastes from north-west europe to the arctic. deep-sea research part ii 42, 1413�1448. kingsley m.c.s., stirling i. & calvert w. 1985. the distribution and abundance of seals in the canadian high arctic, 1980�82. canadian journal of fisheries and aquatic science 42, 1189�1210. kovacs k.m., haug t. & lydersen c. 2009. marine mammals in the barents sea. in e. sakshaug et al. (eds.): ecosystem barents sea. pp. 453�496. trondheim: tapir academic press. kovacs k.m., lydersen c., overland j.e. & moore s.e. 2011. impacts of changing sea-ice conditions on arctic marine mammals. marine biodiversity 41, 181�194. krafft b.a., kovacs k.m. & lydersen c. 2007. distribution of sex and age groups of ringed seals, pusa hispida, in the fastice breeding habitat of kongsfjorden, svalbard. marine ecology progress series 335, 199�206. larsen t. 1967. the trapping and study of polar bears, spitsbergen, 1966. polar record 13, 589�593. larsen t. 1970. polar bear thalarctos maritimus research in spitsbergen. oryx 10, 368�372. larsen t. 1972. air and ship census of polar bears in svalbard (spitsbergen). journal of wildlife management 36, 562�570. larsen t. 1985. polar bear denning and cub production in svalbard, norway. journal of wildlife management 49, 320�326. larsen t. 1986. population biology of the polar bear (ursus maritimus) in the svalbard area. norsk polarinstitutt skrifter 184. oslo: norwegian polar institute. larsen t., jonkel c. & vibe c. 1983. satellite radio-tracking of polar bears between svalbard and greenland. international conference on bear research and management 5, 230�237. larsen t.s. & stirling i. 2009. the agreement on the conservation of polar bears*its history and future. report series 127. tromsø: norwegian polar institute. lentfer j.w. 1969. polar bear tagging in alaska, 1968. polar record 14, 459�462. lentfer j.w. 1975. polar bear denning on drifting sea ice. journal of mammalogy 56, 716�718. lentfer j.w. & hensel r.j. 1980. alaskan polar bear denning. in c.j. martinka & k.l. mcarthur (eds.): bears*their biology and management. a selection of papers from the fourth international conference on bear research and management held at kalispell, montana, usa. february 1977. pp. 101�108. washington, dc: bear biology association. letcher r.j., bustnes j.o., dietz r., jenssen b.m., jorgensen e.h., sonne c., verreault j., vijayan m.m. & gabrielsen g.w. 2010. exposure and effects assessment of persistent organohalogen contaminants in arctic wildlife and fish. science of the total environment 408, 2995�3043. letcher r.j., klasson-wehler e., bergman å. & paasivirta j. 2000. methyl sulfone and hydroxylated metabolites of polychlorinated biphenyls. in j. passivirts (ed.): the handbook of environmental chemistry. pp. 315�359. berlin: springer. lie e., larsen h.j.s., larsen s., johnsen g.m., derocher a.e., lunn n.j., norstrom r.j., wiig ø. & skaare j.u. 2004. does high organochlorine (oc) exposure impair the resistance to infection in polar bears (ursus maritimus)? part i. effect of ocs on the humoral immunity. journal of toxicology and environmental health part a current issues 67, 555�582. lie e., larsen h.j.s., larsen s., johansen g.m., derocher a.e., lunn n.j., norstrom r.j., wiig ø. & skaare j.u. 2005. does high organochlorine (oc) exposure impair the resistance to infection in polar bears (ursus maritimus)? part ii. possible effect of ocs on mitogenand antigen-induced lymphocyte proliferation. journal of toxicology and environmental health part a current issues 68, 457�484. lindenmayer d.b. & likens g.e. 2009. adaptive monitoring: a new paradigm for long-term research and monitoring. trends in ecology & evolution 24, 482�486. lønø o. 1970. the polar bear (ursus maritimus phipps) in the svalbard area. norsk polarinstitutt skrifter 149. oslo: norwegian polar institute. lunn n.j., schliebe s. & born e.w. 2002. polar bears. proceedings of the 13th working meeting of the iucn/ssc polar bear specialist group, 23�28 june 2001, nuuk, greenland. gland: iucn species survival commission. lydersen c., wolkers h., severinsen t., kleivane l., nordøy e.s. & skaare j.u. 2002. blood is a poor substrate for monitoring pollution burdens in phocid seals. science of the total environment 292, 193�203. marchesini g.r., meimaridou a., haasnoot w., meulenberg e., albertus f., mizuguchi m., takeuchi m., irth h. & murk a.j. 2008. biosensor discovery of thyroxine transport disrupting chemicals. toxicology and applied pharmacology 232, 150�160. mauritzen m. 2002. patterns and processes in female polar bear space-use. phd thesis, university of oslo. mauritzen m., belikov s.e., boltunov a.n., derocher a.e., hansen e., ims r.a., wiig ø. & yoccoz n. 2003. functional responses in polar bear habitat selection. oikos 100, 112�124. mauritzen m., derocher a.e. & wiig ø. 2001. space-use strategies of female polar bears in a dynamic sea ice habitat. canadian journal of zoology 79, 1704�1713. mauritzen m., derocher a.e., wiig ø., belikov s.e., boltunov a., hansen e. & garner g.w. 2002. using satellite telemetry to define spatial population structure in polar bears in the norwegian and western russian arctic. journal of applied ecology 39, 79�90. mckinney m.a., iverson s., fisk a.t., sonne c., rigét f.f., letcher r.j., arts m.t., born e.w., rosing-asvid a. & dietz r. 2013. global change effects on the long-term feeding ecology and contaminant exposures of east greenland polar bears. global change biology 19, 2360�2372. m. andersen & j. aars barents sea polar bears citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 17 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 mckinney m.a., letcher r.j., aars j., born e.w., branigan m., dietz r., evans t.j., gabrielsen g.w., peacock e. & sonne c. 2011. flame retardants and legacy contaminants in polar bears from alaska, canada, east greenland and svalbard, 2005�2008. environment international 37, 365�374. mckinney m.a., peacock e. & letcher r.j. 2009. sea iceassociated diet change increases the level of chlorinated and bromiated contaminants in polar bears. environmental science & technology 43, 4334�4339. molnár p.k., derocher a.e., klanjscek t. & lewis m.a. 2011. predicting climate change impacts on polar bear litter size. nature communications 2, 186. molnár p.k., derocher a.e., lewis m.a. & taylor m.k. 2008. modelling the mating system of polar bears: a mechanistic approach to the allee effect. proceedings of the royal society b 275, 217�226. molnár p.k., derocher a.e., thiemann g.w. & lewis m.a. 2010. predicting survival, reproduction and abundance of polar bears under climate change. biological conservation 143, 1612�1622. molnár p.k., klanjscek t., derocher a.e., obbard m.e. & lewis m.a. 2009. a body composition model to estimate mammalian energy stores and metabolic rates from body mass and body length, with application to polar bears. journal of experimental biology 212, 2313�2323. morales j.m., haydon d.t., frair j., holsiner k.e. & fryxell j.m. 2004. extracting more out of relocation data: building movement models as mixtures of random walks. ecology 85, 2436�2445. muir d.c.g., backus s., derocher a.e., dietz r., evans t.j., gabrielsen g.w., nagy j., norstrom r.j., sonne c., stirling i., taylor m.k. & letcher r.j. 2006. brominated flame retardants in polar bears (ursus maritimus) from alaska, the canadian arctic, east greenland, and svalbard. environmental science & technology 40, 449�455. muir d.c.g., norstrom r.j. & simon m. 1988. organochlorine contaminants in the arctic marine food chains: accumulation of specific polychlorinated biphenyls and chlordanerelated compounds. environmental science & technology 22, 1071�1079. nilssen k.t., pedersen o.p., folkow l.p. & haug t. 2000. food consumption estimates of barents sea harp seals. nammco scientific publications 2, 9�27. nilsson a.e. & huntington h.p. 2009. arctic pollution 2009. oslo: arctic monitoring and assessment programme. nordøy e.s., folkow l.p., potelov v., prichtchemikhine v. & blix a.s. 1998. migratory patterns and dive behaviour of barents sea harp seals. in: abstracts: the world marine mammal science conference. monaco, 20�24 january. p. 97. la rochelle: center for research on marine mammals. norheim g., skaare j.u. & wiig ø. 1992. some heavy metals, essential elements, and chlorinated hydrocarbons in polar bear (ursus maritimus) at svalbard. environmental pollution 77, 51�57. norstrom r.j., belikov s.e., born e.w., garner g.w., malone b., olpinski s., ramsay m.a., schliebe s., stirling i., stishov m.s., taylor m.k. & wiig ø. 1998. chlorinated hydrocarbon contaminants in polar bears from eastern russia, north america, greenland, and svalbard: biomonitoring of arctic pollution. archives of environmental contamination and toxicology 35, 354�367. obbard m.e., thiemann g.w., peacock e. & debruyn t.d. (eds.) 2010. polar bears. proceedings of the 15th working meeting of the iucn polar bear specialist group, 29 june�3 july 2009. copenhagen, denmark. occasional paper of the iucn species survival commission 43. gland: international union for the conservation of nature. oehme m. 1991. dispersion and transport paths of toxic persistent organochlorines to arctic*levels and consequences. science of the total environment 106, 43�53. oksanen a., åsbakk k., prestrud k.w., aars j., derocher a.e., tryland m., wiig ø., dubey j.p., sonne c., dietz r., andersen m. & born e.w. 2009. prevalence of antibodies against toxoplasma gondii in polar bears (ursus maritimus) from svalbard and east greenland. journal of parasitology 95, 89�94. olsen g.h., mauritzen m., derocher a.e., sørmo e.g., skaare j.u., wiig ø. & jenssen b.m. 2003. space-use strategy is an important determinant of pcb concentrations in female polar bears in the barents sea. environmental science & technology 37, 4919�4924. olsson m., andersson ö., bergman å., blomkvist g., frank a. & rappe c. 1992. contaminants and diseases in seals from swedish waters. ambio 21, 561�562. øritsland n.a. 1970. temperature regulation of the polar bear (thalarctos maritimus). journal of comparable biochemistry and physiology series a 37, 225�233. oskam i.c., ropstad e., dahl e., lie e., derocher a.e., wiig ø., larsen s., wiger r. & skaare j.u. 2003. organochlorines affect the major androgenic hormone, testosterone, in male polar bears (ursus maritimus) at svalbard. journal of toxicology and environmental health part a 66, 2119�2139. oskam i.c., ropstad e., lie e., derocher a.e., wiig ø., dahl e., larsen s. & skaare j.u. 2004. organochlorines affect the steroid hormone cortisol in free-ranging polar bears (ursus maritimus) at svalbard, norway. journal of toxicology and environmental health part a 67, 959�977. overrein ø. 2002. virkninger av motorferdsel på fauna og vegetasjon: kunnskapsstatus med relevans for svalbard. (effects of motorized traffic on fauna and vegetation: the status of knowledge relevant for svalbard.) report series 119. tromsø: norwegian polar institute. parks e.k., derocher a.e. & lunn n.j. 2006. seasonal and annual movement patterns of polar bears on the sea ice of hudson bay. canadian journal of zoology 84, 1281�1294. parovshchikov v.y. 1964. a study on the population of polar bear, ursus (thalarctos) maritimus phipps, of franz joseph land. acta societatis zoologicae bohemoslovenicae 28, 167�177. pentreath r.j., jefferies d.f., talbot j.w., lovett m.b. & harvey b.r. 1982. transuranic cycling behaviour in marine environment. iaea-tecdoc-265. vienna: international atomic energy agency. barents sea polar bears m. andersen & j. aars 18 (page number not for citation purpose) citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 pilfold n.w., derocher a.e., stirling i., richardson e. & andriashek d. 2012. age and sex composition of seals killed by polar bears in the eastern beaufort sea. plos one 7(7), e41429, doi: 10.1371/journal.pone.0041429. polar bear range states 2015. circumpolar action plan: conservation strategy for polar bears. a product of the representatives of the parties to the 1973 agreement on the conservation of polar bears. accessed on the internet at http://naalakkersuisut.gl/en/ naalakkersuisut/departments/fiskeri-fangst-og-landbrug/ isbjorn/the-circumpolar-action-plan-and-executivesummary on 21 june 2016 polischuk s.c. 1999. organochlorine dynamics in free-ranging polar bears and their cubs. phd thesis, university of saskatchewan. polischuk s.c., norstrom r.j. & ramsay m.a. 2002. body burdens and tissue concentrations of organochlorines in polar bears (ursus maritimus) vary during seasonal fasts. environmental pollution 118, 29�39. prestrud p. & stirling i. 1994. the international polar bear agreement and the current status of polar bear conservation. aquatic mammals 20, 1�12. ramsay m. & stirling i. 1990. fidelity of female polar bears to winter den sites. journal of mammalogy 71, 233�236. reeves r.r. 1998. distribution, abundance and biology of ringed seals (phoca hispida): an overview. nammco scientific publications 1, 9�45. regehr e.v., hunter c.m., caswell h., amstrup s.c. & stirling i. 2010. survival and breeding of polar bears in the southern beaufort sea in relation to sea ice. journal of animal ecology 79, 117�127. regehr e.v., lunn n.j., amstrup s.c. & stirling l. 2007. effects of earlier sea ice breakup on survival and population size of polar bears in western hudson bay. journal of wildlife management 71, 2673�2683. richardson e., stirling i. & hik d.s. 2005. polar bear (ursus maritimus) maternity denning habitat in western hudson bay: a bottom-up approach to resource selection functions. canadian journal of zoology 83, 860�870. rigét f., bossi r., sonne c., vorkamp k. & dietz r. 2013. trends of perfluorochemicals in greenland ringed seals and polar bears: indications of shifts to decreasing trends. chemosphere 93, 1607�1614. rode k.d., amstrup s.c. & regehr e.v. 2010. reduced body size and cub recruitment in polar bears associated with sea ice decline. ecological applications 20, 768�782. rondinini c., rodrigues a.s.l. & boitani l. 2011. the key elements of a comprehensive global mammal conservation strategy. philosophical transactions of the royal society b 355, 2591�2597. sahanatien v. & derocher a.e. 2012. monitoring sea ice habitat fragmentation for polar bear conservation. animal conservation 15, 397�406. sander g., hanssen-bauer i., bjørge a. & prestrud p. 2005. miljøovervåking av svalbard og jan mayen*mosj. report series 123. tromsø: norwegian polar institute. shapiro i., colony r. & vinje t. 2003. april sea ice extent in the barents sea, 1850�2001. polar research 22, 5�10. skaare j.u., bernhoft a., derocher a., gabrielsen g.w., goksøyr a., henriksen e., larsen h.j., lie e. & wiig ø. 2000. organochlorines in top predators at svalbard* occurrence, levels and effects. toxicological letters 112/113, 103�109. smith t.g. 1980. polar bear predation of ringed and bearded seals in the land-fast sea ice habitat. canadian journal of zoology 58, 2201�2209. smith t.g. & lydersen c. 1991. availability of suitable land-fast ice and predation as factors limiting ringed seal populations, phoca hispida, in svalbard. polar research 10, 585�594. smith t.g. & stirling i. 1975. the breeding habitat of the ringed seal (phoca hispida). the birth lair and associated structures. canadian journal of zoology 53, 1297�1305. sonne c. 2010. health effects from long-range transported contaminants in arctic top predators: an integrated review based on studies of polar bears and relevant model species. environmental international 36, 461�491. stirling i. 1974. midsummer observations on behavior of wild polar bears (ursus maritimus). canadian journal of zoology 52, 1191�1198. stirling i. & andriashek d. 1992. terrestrial maternity denning of polar bears in the eastern beaufort sea area. arctic 45, 363�366. stirling i., andriashek d. & calvert w. 1993. habitat preferences of polar bears in the western canadian arctic in late winter and spring. polar record 29, 13�24. stirling i. & archibald w.r. 1977. aspects of predation of seals by polar bears. journal of the fisheries research board of canada 34, 1126�1129. stirling i. & derocher a.e. 1993. possible impacts of climatic warming on polar bears. arctic 46, 240�245. stirling i. & derocher a.e. 2012. effects of climate warming on polar bears: a review of the evidence. global change biology 18, 2694�2706. stirling i., lunn n.j. & iacozza j. 1999. long-term trends in the population ecology of polar bears in western hudson bay in relation to climatic change. arctic 52, 294�306. stirling i. & mcewan e.h. 1975. caloric value of whole ringed seals (phoca hispida) in relation to polar bear (ursus maritimus) ecology and hunting behavior. canadian journal of zoology 53, 1021�1027. strand p., howard b.j., aarkrog a., balonov m., tsaturov y., bewers j.m., salo a., sickel m., bergman r. & rissanen k. 2002. radioactive contamination in the arctic*sources, dose assessment and potential risks. journal of environmental radioactivity 60, 5�21. taylor m.k., demaster d.p., bunnell f.l. & schweinsburg r.e. 1987. modelling the sustainable harvest of female polar bears. journal of wildlife management 51, 811�820. taylor m.k., laake j., mcloughlin p.d., born e.w., cluff h.d., ferguson s.h., rosing-asvid a., schweinsburg r. & messier f. 2005. demography and viability of a hunted population of polar bears. arctic 58, 203�214. m. andersen & j. aars barents sea polar bears citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 19 (page number not for citation purpose) http://10.1371/journal.pone.0041429 http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://naalakkersuisut.gl/en/naalakkersuisut/departments/fiskeri-fangst-og-landbrug/isbjorn/the-circumpolar-action-plan-and-executive-summary http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 taylor m.k. & lee l.j. 1995. distribution and abundance of canadian polar bear populations: a management perspective. arctic 48, 147�154. thiemann g.w., iverson s.j. & stirling i. 2008. polar bear diets and arctic marine food webs: insights from fatty acid analysis. ecological monographs 78, 591�613. tryland m., derocher a.e., wiig ø. & godfroid j. 2001. brucella sp antibodies in polar bears from svalbard and the barents sea. journal of wildlife diseases 37, 523�531. tryland m., neuvonen e., huovilainen a., tapiovaara h., osterhaus a., wiig o. & derocher a.e. 2005. serologic survey for selected virus infections in polar bears at svalbard. journal of wildlife diseases 41, 310�316. verreault j., muir d.c.g., norstrom r.j., stirling i., fisk a.t., gabrielsen g.w., derocher a.e., evans t., dietz r., sonne c., sandala g.m., taylor m.k., nagy j. & letcher r.j. 2005. chlorinated hydrocarbon contaminants and metabolites in polar bears (ursus maritimus) from svalbard, east greenland, alaska and the canadian arctic during 1999�2002. science of the total environment 351, 369�390. villanger g.d., jenssen b.m., fjeldberg r.r., letcher r.j., muir d.c.g., kirkegaard m., sonne c. & dietz r. 2011. exposure to mixtures of organohalogen contaminants and associative interactions with thyroid hormones in east greenland polar bears (ursus maritimus). environment international 37, 694�708. vinebrooke r.d., cottingham k.l., norberg j., scheffer m., dodson s.i., maberly s.c. & sommer u. 2004. impacts of multiple stressors on biodiversity and ecosystem functioning: the role of species co-tolerance. oikos 104, 451�457. vongraven d. 2009. guest editorial: the ballyhoo over polar bears. polar research 28, 323�326. vongraven d., aars j., amstrup s., atkinson s.n., belikov s.e., born e.w., debruyn t.d., derocher a.e., durner g., gill m., lunn n., obbard m.e., omelak j., ovsyanikov n., peacock e., richardson e., sahanatien v., stirling i. & wiig ø. 2012. a circumpolar monitoring framework for polar bears. ursus monograph series 5. ursus 23, 1�66. vongraven d. & peacock e. 2011. development of a pan-arctic monitoring plan for polar bears: background paper. caff monitoring series report 1. akureyri: conservation of arctic flora and fauna . watts p.d. & hansen s.e. 1987. cyclic starvation as a reproductive strategy in the polar bear. symposia of the zoological society of london 57, 305�318. wiig ø. 1995. distribution of polar bears (ursus maritimus) in the svalbard area. journal of zoology 237, 515�529. wiig ø. 1998. survival and reproductive rates for polar bears at svalbard. ursus 10, 25�32. wiig ø. 2005. are polar bears threatened? science 309, 1814�1815. wiig ø., aars j. & born e.w. 2008. effects of climate change on polar bears. science progress 91, 151�173. wiig ø., amstrup s., atwood t., laidre k., lunn n., obbard m., regehr e. & thiemann g. 2015. ursus maritimus. the iucn red list of threatened species 2015, e.t22823a14871490, http://dx.doi.org/10.2305/iucn.uk.2015-4.rlts.t22823a 14871490.en. accessed on the internet at http://www. iucnredlist.org/details/22823/0 on 27 may 2016 wiig ø. & derocher a. 1999. application of aerial survey methods to polar bears in the barents sea. in g.w. garner et al. (eds.): marine mammal survey and assessment methods. pp. 27�36. rotterdam: balkema. wiig ø., derocher a.e. & belikov s.e. 1999. ringed seal (phoca hispida) breeding in the drifting pack ice of the barents sea. marine mammal science 15, 595�598. wilson k.a., evans m.c., di marco m., green d.c., boitani l., possingham h.p., chiozza f. & rondinini c. 2011. prioritizing conservation investments for mammal species globally. philosophical transactions of the royal society b 366, 2670�2680. wolkers h., krafft b.a., van bavel b., helgason l.b., lydersen c. & kovacs k.m. 2008. biomarker responses and decreasing contaminant levels in ringed seals (pusa hispida) from svalbard, norway. journal of toxicology and environmental health 71, 1009�1018. yasuda t. & arai n. 2005. fine-scale tracking of marine turtles using gps-argos ptts. zoological science 22, 547�553. zeyl e., ehrich d., aars j., bachmann l. & wiig ø. 2010. denning-area fidelity and mitochondrial dna diversity of female polar bears (ursus maritimus) in the barents sea. canadian journal of zoology 88, 1139�1148. barents sea polar bears m. andersen & j. aars 20 (page number not for citation purpose) citation: polar research 2016, 35, 26029, http://dx.doi.org/10.3402/polar.v35.26029 http://dx.doi.org/10.2305/iucn.uk.2015-4.rlts.t22823a14871490.en http://dx.doi.org/10.2305/iucn.uk.2015-4.rlts.t22823a14871490.en http://www.iucnredlist.org/details/22823/0 http://www.iucnredlist.org/details/22823/0 http://www.polarresearch.net/index.php/polar/article/view/26029 http://dx.doi.org/10.3402/polar.v35.26029 doi:10.3402/polar.v34.25055 r e s e a r c h / r e v i e w a r t i c l e assessing regional populations of ground-nesting marine birds in the canadian high arctic mark maftei,1,2 shanti e. davis1,2 & mark l. mallory3 1 high arctic gull research group, bamfield, british columbia v0r 1b0, canada 2 department of biology, memorial university of newfoundland, st. john’s, newfoundland a1c 5s7, canada 3 department of biology, acadia university, wolfville, nova scotia b4p 2r6, canada keywords ground-nesting; seabirds; high arctic; nunavut; common eider; arctic tern. correspondence mark l. mallory, department of biology, acadia university, 15 university ave., wolfville, nova scotia b4p 2r6, canada. e-mail: mark.mallory@acadiau.ca abstract the queens channel region of nunavut is an ecologically distinct area within the canadian high arctic consisting of an extensive archipelago of small, lowlying gravel islands throughout which form several localized but highly productive polynyas. we used aerial survey and colony-monitoring data to assess regionaland colony-level fluctuations in the number of birds in this region between 2002 and 2013. regional and colony-specific monitoring suggested that common eider (somateria mollissima) numbers are increasing, while numbers of arctic terns (sterna paradisaea) may be in decline. based on these data, we suggest that even infrequent comprehensive surveys are more useful than annual monitoring at specific sites in generating an accurate assessment of ground-nesting seabird populations at the regional level, and that dramatic fluctuations at individual colonies probably belie the overall stability of regional populations. knowledge of the distribution and abundance of most avian species nesting in the canadian high arctic remains patchy and incomplete in part because of the extreme remoteness and large size of the region as well as the logistical difficulties inherent in conducting surveys there. some catalogues of large seabird colonies, particularly cliff-nesting species, in the canadian arctic are available (nettleship 1973; mallory & fontaine 2004), but species nesting in low densities or only in isolated areas of suitable habitat have probably been overlooked (gaston et al. 2012). current estimates of ground-nesting seabird populations in the canadian arctic are particularly uncertain due to partial or incomplete survey coverage, extrapolation from small sample sizes, and a general lack of understanding of how variability in local habitat suitability may affect annual numbers of breeders (gaston et al. 2012). in the arctic, mammalian predators exert strong predation pressure on ground-nesting birds (birkhead & nettleship 1995; smith et al. 2010), and most species have adopted a strategy of nesting in low densities over large areas. this tendency makes most populations difficult to survey and monitor effectively, a problem further complicated by unpredictable changes in local abundance (clark & shutler 1999; egevang & frederiksen 2011) and the reduced detectability of cryptic or easily overlooked species (meltofte 2001). the ocean passage that extends from penny strait through queens channel to macdougall sound (hereafter collectively referred to as queens channel) contains an extensive archipelago of small, low-elevation gravel islands. the shallow bathymetry and strong tidal currents in this area lead to the formation of several localized and highly productive polynyas (hannah et al. 2009), which provide important foraging habitat for many bird and mammal species (stirling 1997). this region is unique within the canadian high arctic and is used by a large number of bird species which exploit the rich foraging opportunities provided by polynyas early in the breeding season when most of the surrounding water remains frozen (mallory & gilchrist 2003; mallory & fontaine 2004; maftei et al. 2012). this area had already been recognized as an important breeding area for ross’s gull (rhodostethia rosea) after the first nests in north america were found on the cheyne islands in north-western queens channel (macdonald 1978), and more recent surveys have identified other islands in the area used by polar research 2015. # 2015 m. maftei et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2015, 34, 25055, http://dx.doi.org/10.3402/polar.v34.25055 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/25055 http://dx.doi.org/10.3402/polar.v34.25055 this species for nesting (maftei et al. 2012). a partial survey of queens channel in 2002 and 2003 (mallory & gilchrist 2003) revealed that substantial numbers of arctic terns (sterna paradisaea) and common eiders (somateria mollissima) also nest throughout the islands in this archipelago. the northernmost known north american colonies of sabine’s gull (xema sabini) and the largest known ivory gull (pagophila eburnea) colony are also found in the queens channel region. a more thorough understanding of the size, distribution and dynamics of groundnesting seabird populations in this area is of critical importance in developing practical management and conservation measures for the region at a time of increasing interest in industrial development of the arctic. the objectives of this study were to (1) update and augment the mallory & gilchrist (2003) survey to examine potential breeding sites for marine birds in queens channel, and (2) assess the numbers and distribution of ground-nesting marine birds in this poorly known region. methods study area we defined a study area extending between 758 n and 76855?n and 102840?w and 93847?w, encompassing an archipelago of approximately 120 islands which run from southern penny strait through queens channel and macdougall sound into northern barrow strait. this area is bound by bathurst island to the west, devon island to the north-east and cornwallis island to the south-east (fig. 1). after excluding islands that were very large (i.e., capable of supporting resident mammalian predators), those that were effectively extensions of much larger islands (i.e., would be joined by ice bridges for much of the year), and those that were covered at highest tides, we had 80 islands to choose from. we used arcgis software (version 10, environmental systems research institute, redlands, ca) to compile topographic, land cover and digital elevation model maps of the study area, and from these data we selected our target islands to survey. these comprised sites that mallory & gilchrist (2003) had identified as important as well as sites that had similar physiographic features to those in the earlier study. we determined mean island elevation (m above sea level [asl]) and island area (ha) for these sites. although elevation and area were correlated (rs31 �0.89, pb0.001), we assessed these criteria separately. the region has numerous small polynyas in most years (mallory & gilchrist 2003), which are variable in annual size and shape (and which vary through the season), but islands in this study were generally 3595 km (range 0�110 km) from typical polynya locations (polynyas from hannah et al. 2009). surveys we surveyed 30 islands in queens channel from a bell 206 l4 helicopter on 19 and 23 june 2012 (fig. 1). seventeen of these islands had never been surveyed before, 10 had been previously surveyed on 16 july 2002 by mallory & gilchrist (2003), and one, nasaruvaalik island, has been surveyed and monitored with varying intensity of effort annually since 2002. while flying around the perimeter of small islands or transects over larger ones from an altitude of approximately 100 m, three observers independently recorded all birds seen on or in the immediate vicinity of each island, and the overall high count for each species was recorded. we also surveyed six islands on foot while searching for ross’s gull nests on the same dates as above. observations from nasaruvaalik island were recorded on 25 june 2012 by three ground-based observers. assessment of regional populations we assessed fluctuations in numbers of birds attending island colonies at the regional level by comparing the difference in observed numbers of birds at 10 islands surveyed in both 2002 and 2012 (table 1). we also examined fluctuations in annual attendance at the colony fig. 1 overview of study area. numbers correspond to islands in table 1. approximate centres of recurring polynyas are indicated by asterisks. assessing populations of ground-nesting marine birds m. maftei et al. 2 (page number not for citation purpose) citation: polar research 2015, 34, 25055, http://dx.doi.org/10.3402/polar.v34.25055 http://www.polarresearch.net/index.php/polar/article/view/25055 http://dx.doi.org/10.3402/polar.v34.25055 table 1 observed numbers of birds on islands in queens channel in july 2002 and june 2012. bird species are as follows: red-throated loon (gavia stellata; rtlo); brant (branta hrota, bran); king eider (somateria spectabilis; kiei); long-tailed duck (clangula hyemalis; ltdu); glaucous gull (larus hyperboreus; glgu); sabine’s gull (xema sabini; sagu); ross’s gull (rhodostethia rosea; rogu); blacklegged kittiwake (rissa tridactyla; blki); arctic tern (sterna paradisaea; arte); red phalarope (phalaropus fulicarius; reph); baird’s sandpiper (calidris bairdii; basa); parasitic jaeger (stercorarius parasitica; paja); common raven (corvus corax; cora); snow goose (chen caerulescens; sngu); semipalmated sandpiper (calidris pusilla; sesa); purple sandpiper (calidris maritima; pusa); snow bunting (plectrophenax nivalis; snbu); ivory gull (pagophila eburnea; ivgu); black guillemot (cepphus grylle; blgu). map location survey year species observed 2002/2012 # n8 w8 island 2002 2012 species birds % change rtlo bran coei kiei ltdu glgu sagu rogu blki arte reph other 1 76.01 97.16 reid x 3 184 14 100 70 2 76.29 97.51 south cheyne x 5 782 �67% 2 164 10 6 600 x 10 467 2 60 175 60 11 2 4 50 100 basa(3) 3 76.31 97.52 middle cheyne x 4 227 �41% 2 212 11 paja(2) x 4 135 2 50 2 81 4 76.33 97.52 north cheyne x 4 70 �100% 2 2 16 50 x 2 140 30 110 5 76.81 101.26 seymour x 0 0 6 76.68 99.73 harwood x 1 2 2 7 76.63 98.16 north hooker x 2 12 �275% 11 cora(1) x 3 45 23 21 1 8 76.61 98.10 south hooker x 4 118 �74% 13 3 100 2 x 3 68 65 2 1 9 76.55 97.72 irving x 3 176 �110% 12 24 140 x 4 84 1 50 31 sngo(2) 10 76.49 97.12 hyde parker x 2 42 34 8 11 76.35 96.22 assistance x 2 244 �43% 4 240 x 3 171 20 1 150 12 76.18 96.95 des voeux x 1 2 �1750% 2 x 3 37 6 30 1 13 75.83 96.30 nasaruvaalik x 7 1417 �11% 3 6 375 30 900 100 cora(3) x 17 1579 3 175 400 20 8 2 60 8 520 350 22 sesa(3); pusa, cora snbu(2); ivgu, paja(1) 14 75.79 96.56 crozier x 1 60 �300% 60 x 5 15 2 1 5 6 paja(1) 15 75.63 96.86 milne x 1 2 2 16 76.57 99.27 young inlet x 2 180 120 60 17 76.60 101.80 mallory x 0 0 18 76.60 101.96 gilchrist x 0 0 19 75.54 97.21 kalivik x 7 86 2 9 1 1 1 65 7 20 75.49 97.23 emikutailaq x 7 383 1 9 10 2 350 7 snbu(4) 21 75.39 97.53 chip x 1 2 2 22 75.35 97.59 big neal x 4 18 2 12 snbu(3); paja(1) 23 75.32 97.53 neal polynya x 4 141 2 130 8 1 24 75.31 97.50 little neal x 0 0 25 75.25 97.16 truro x 2 7 4 3 m . m a fte i e t a l. a s s e s s in g p o p u la tio n s o f g ro u n d -n e s tin g m a rin e b ird s c ita tio n : p o la r r e se a rc h 2 0 1 5 , 3 4 , 2 5 0 5 5 , h ttp ://d x .d o i.o rg /1 0 .3 4 0 2 /p o la r.v 3 4 .2 5 0 5 5 3 (p a g e n u m b e r n o t fo r c ita tio n p u rp o se ) http://www.polarresearch.net/index.php/polar/article/view/25055 http://dx.doi.org/10.3402/polar.v34.25055 level by comparing the variation in annual maximum and mean numbers for 25 regularly observed species over six years at nasaruvaalik island (table 2). we calculated mean values based only on july observations to more accurately reflect the numbers of breeding birds which would be present and incubating at that time. the yearly maximum is a more accurate indication of the total number of birds (including non-breeders) using the island. for each year, we determined the total annual abundance representing the sum of the maximum high count for each of the 25 species as well as a total mean representing the mean of daily counts in july for each species (n �31 for all years). we then compared these values between years and across all six years. we also compared the per-year variation in annual maximum and mean observed numbers for arctic terns and common eiders separately. comparisons were conducted using pearson r or spearman rs. all means are presented9se. results for each island surveyed (table 1), we calculated species abundance and richness. the number of any species counted at a site tended to be higher for islands that had lower elevation (fig. 2: rs � �0.23, n �30, p �0.071) and smaller island area (fig. 3: rs � �0.26, p �0.048). however, species richness was not correlated with elevation or area (figs. 2�4; all rs5�0.13, all p�0.21). species richness per island was low (mean 2.992.2, range�0�17), with a few notable exceptions: nasaruvaalik (17 species), south cheyne (10), emikutailaq (8). these three islands also had the highest observed abundance of birds (n �1579, 467 and 383, respectively). surveys we flew one-time surveys of 30 islands and observed 4451 individual birds of 20 species (table 2). the most abundant and widely distributed species were arctic terns (1546 individuals on 16 islands) and common eiders (1497 on 21 islands), whereas glaucous gulls (larus hyperboreus), though far less numerous, were also broadly distributed (86 on 16 islands). seventeen other species were also observed, including sabine’s gulls (xema sabini; 60 on five islands), red phalaropes (phalaropus fulicarius; 233 on seven islands), brant (branta bernicla; 315 on 10 islands) and red-throated loons (gavia stellata; 14 on seven islands). five nesting pairs of ross’s gulls (14 on three islands) were also observed. assessment of regional populations for survey data from 10 islands surveyed in both 2002 and 2012, there was a mean 1859177% increase pert a b le 1 (c o n ti n u e d ) m a p l o c a ti o n s u rv e y y e a r s p e c ie s o b se rv e d 2 0 0 2 /2 0 1 2 # n 8 w 8 is la n d 2 0 0 2 2 0 1 2 s p e c ie s b ir d s % c h a n g e r t l o b r a n c o e i k ie i l t d u g l g u s a g u r o g u b l k i a r t e r e p h o th e r 2 6 7 5 .2 7 9 7 .8 4 o u tl ie r x 2 5 4 p u s a (1 ) 2 7 7 5 .3 5 9 6 .9 1 t h o m a s h o n e y x 2 1 3 1 1 2 2 8 7 5 .3 1 9 6 .6 4 ik a g g u a q x 4 5 0 1 2 3 6 b l g u (1 1 ) 2 9 7 5 .2 6 9 6 .3 4 t a d m a n x 3 5 2 2 b l g u (1 ) 3 0 7 5 .2 3 9 6 .3 7 l it tl e t a d m a n x 1 2 2 3 1 7 6 .8 8 9 7 .1 8 h o rn b y x 4 1 4 5 5 6 5 6 0 1 5 3 2 7 6 .9 0 9 6 .9 7 r u ss e l x 3 2 6 2 2 6 0 2 0 0 3 3 7 6 .6 6 9 6 .7 0 c ra c ro ft x 4 3 0 0 1 2 1 8 0 8 1 0 0 3 4 7 6 .6 4 9 6 .5 4 t o m s x 4 1 8 9 8 1 7 0 5 6 3 5 7 6 .6 2 9 6 .4 6 k e rr x 4 8 8 1 7 5 0 2 0 p a ja (1 ) 3 6 7 6 .6 0 9 6 .3 8 f a ir h o lm e x 1 6 6 3 7 7 6 .5 7 9 6 .1 2 w a lr u s x 2 6 4 p a ja (2 ) t o ta l o b se rv e d 3 5 1 6 4 4 5 1 a v g . 3 .3 1 7 9 6 9 2 7 7 % 7 /7 6 6 /2 5 9 5 7 0 /8 1 7 0 /8 0 1 3 /1 0 3 4 /5 1 3 0 /6 7 0 /1 2 0 /5 2 0 2 2 1 9 /6 9 7 1 6 3 /2 0 4 assessing populations of ground-nesting marine birds m. maftei et al. 4 (page number not for citation purpose) citation: polar research 2015, 34, 25055, http://dx.doi.org/10.3402/polar.v34.25055 http://www.polarresearch.net/index.php/polar/article/view/25055 http://dx.doi.org/10.3402/polar.v34.25055 table 2 annual maximum and mean numbers of commonly observed species on nasaruvaalik island from 2007 to 2012. boldface indicates maximum observed values across all six years. 2007 (n a �37) 2008 (n a �62) 2009 (n a �43) 2010 (n a �52) 2011 (n a �87) 2012 (n a �60) across all years species year july year july year july year july year july year july max max july sd 9 cv b max mean max mean max mean max mean max mean max mean year mean red-throated loon c 6 3 4 3 5 3 9 3 15 4 13 4 15 2011 3 1 20 brant c 48 5 15 6 92 40 100 21 80 10 180 50 180 2012 22 15 68 snow goose d 4 1 4 0 11 0 8 0 2 0 16 0 16 2012 0 2 n/a common eider c 200 91 400 205 400 288 440 188 800 249 600 268 800 2011 215 50 23 king eiderc 60 24 18 1 7 1 50 1 130 1 150 1 150 2012 5 18 361 long-tailed duck c 65 14 40 20 51 26 30 12 120 25 50 17 120 2011 19 5 28 glaucous gullc 4 2 11 2 5 2 53 4 15 3 5 3 53 2010 3 3 99 ivory gull 0 0 2 1 1 1 1 0 4 2 1 0 4 2011 1 0 55 sabine’s gullc 30 20 20 14 26 17 38 21 300 41 68 44 300 2011 26 14 52 ross’s gull c 12 5 6 4 6 3 5 1 7 3 12 6 12 ’07/’12 4 1 17 black-legged kittiwake 160 47 30 2 6 1 30 0 48 5 520 21 520 2012 13 39 301 arctic tern c 402 275 750 250 500 374 500 333 900 583 700 403 900 2011 370 30 8 parasitic jaegerc 5 3 5 3 5 3 16 4 5 2 4 2 16 2010 3 1 19 long-tailed jaeger 2 2 2 1 3 1 5 1 10 2 6 2 10 2011 1 1 59 pomarine jaeger 2 0 2 2 2 1 26 7 2 1 2 1 26 2010 2 3 130 peregrine falcon 0 0 1 0 1 0 1 0 0 0 0 0 1 n/a 0 0 n/a red knot 30 9 20 10 20 13 35 7 47 14 18 9 47 2011 10 3 27 ruddy turnstone 23 4 2 1 1 1 2 0 8 1 13 1 23 2007 1 3 213 purple sandpiperd 4 2 2 1 6 6 2 0 120 2 7 2 120 2011 2 10 472 sanderling 2 2 3 3 0 0 0 0 35 1 6 3 35 2011 1 3 248 baird’s sandpiper 0 0 6 0 1 1 0 0 11 0 2 0 11 2011 0 2 n/a red phalarope 18 7 16 6 14 3 7 2 160 10 2500 284 2500 2012 52 196 379 common raven 2 1 3 2 2 1 4 1 2 2 2 1 4 2010 1 0 n/a lapland longspur 2 0 1 0 5 1 2 0 0 0 1 1 5 2009 0 1 n/a snow buntingd 2 1 4 2 4 2 2 1 9 1 8 1 9 2011 1 1 52 total 1083 516 1368 537 1175 791 1378 607 2876 961 4906 1125 4906 755 a days at site. b coefficient of variation. c species breeding in all years. d species breeding in at least one year. fig. 2 the relationship between mean island elevation and observed richness and abundance of birds in queens channel, showing declines in diversity or numbers with increasing island elevation. values are log transformed to correct skewing when visually represented. fig. 3 the relationship between island area and observed richness and abundance of birds in queens channel, showing a trend of reduced diversity and numbers with increasing island size. values are log transformed to correct skewing when visually represented. m. maftei et al. assessing populations of ground-nesting marine birds citation: polar research 2015, 34, 25055, http://dx.doi.org/10.3402/polar.v34.25055 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25055 http://dx.doi.org/10.3402/polar.v34.25055 island in total birds observed over a decade (table 1), but when this was weighted by the proportion of birds that each island represented out of the total birds from the 10 islands, this changed dramatically to a mean 1.291.3% decrease per island (or �0.12% per year). not surprisingly, proportionately large increases in numbers of birds occurred on islands with relatively few birds in 2002*for example, the 18.5-fold difference for desvoeux shown in table 1*while large colonies showed much less change (e.g., nasaruvaalik, with a 1.1-fold difference). the changes in total numbers of birds were driven by contrasting trends in the two most common species. over the decade, data from one-day aerial surveys suggested that numbers of common eiders on the 10 islands increased overall by 43% (4.291.0% per island, weighted by initial colony size), with three islands that had no eiders in 2002 supporting colonies in 2012. in contrast, numbers of arctic terns declined by 68% (6.993.2% per island), with changes in tern nesting distribution observed on the islands. three islands supporting tern colonies in 2002 had none in 2012, while two islands had no terns in 2002, but had small colonies in 2012. glaucous gulls showed an overall 50% increase (5.292.5% per island), with small colonies appearing on six islands in 2012, while two colonies from 2002 were not present in 2012. when we compared the information from the regional surveys a decade apart to the annual monitoring at nasaruvaalik island (using mean july numbers of birds), a different pattern emerged. the mean total number of birds observed daily at nasaruvaalik island in july increased 118% between 2007 and 2012 (r6 �0.89, p�0.02), and would be even greater (353%) using maximum number of birds observed (table 2). daily counts of common eiders (rs �0.69, p �0.13), arctic terns (rs �0.72, p �0.11) and glaucous gulls (rs �0.74, p �0.11) all suggested increases over this period (high positive correlations) although none of the patterns were statistically significant, likely a consequence of the small number of years studied. for 18 of 25 species (72%), highest counts occurred in the last two years of study (table 2). the greatest variation tended to occur for species that rarely or never breed at nasaruvaalik island, and is attributable to counts from occasional occupation of the island by large flocks of non-breeding birds in some years (table 2), such as red phalaropes (n �2500) in 2012. non-breeding or failed breeders presumably also influenced counts of the main breeding species as well. for example, in some years, only one-third of the maximum count of terns or eider (fig. 4) was presumed to be breeding, as indexed by the july mean count (which tended to reflect numbers of breeding birds on the island). discussion most of the islands supporting larger numbers of birds in queens channel share a suite of easily assessed physical and ecological characteristics; the greatest abundance and richness of nesting birds were found on small, lowlying islands and the two with the greatest abundance and diversity (south cheyne, nasaruvaalik) were situated beside open water (polynyas) during the early breeding season (hannah et al. 2009). such a habitat offers groundnesting seabirds easy access to productive foraging areas (maftei et al. 2012), and confers some degree of protection from mammalian predators (mallory & gilchrist fig. 4 comparison of maximum (entire bar) and july mean (black) numbers of (a) arctic terns and (b) common eiders on nasaruvaalik island in each of six years of study. assessing populations of ground-nesting marine birds m. maftei et al. 6 (page number not for citation purpose) citation: polar research 2015, 34, 25055, http://dx.doi.org/10.3402/polar.v34.25055 http://www.polarresearch.net/index.php/polar/article/view/25055 http://dx.doi.org/10.3402/polar.v34.25055 2003), probably because they are too small for mammals (e.g., mustelids, foxes) to reside year-round. given the challenges of conducting surveys in the high arctic, we recommend that a priori assessment and ranking of potential survey targets be conducted*effectively ecological niche factor analysis using even coarse habitat suitability models and gis software (danks & klein 2002; hirzel et al. 2002; long et al. 2008), to maximize the likelihood of encountering birds while minimizing flight times and associated costs. the snow cover conditions in the high arctic can vary substantially across years, so discrete and limited patches of nesting habitat on small islands may be suitable for nesting in one year and unsuitable in the next (e.g., meltofte 2001). as such, numbers of nesting birds at island sites are likely to vary significantly between years. colonies of arctic terns, for example (the most abundant species in our surveys), are known to fluctuate dramatically in numbers between years in response to local changes in habitat suitability, while the regional queens channel population may remain stable (e.g., egevang & frederiksen 2011). similar patterns have been reported for a variety of other arctic species (falardeau et al. 2003; gaston et al. 2005; mallory & forbes 2007; moe et al. 2009). long-term monitoring on nasaruvaalik island (table 2) suggests that several species such as ross’s gulls, sabine’s gulls, brant and red phalaropes may defer breeding in years when regional conditions are suboptimal, or may nest on neighbouring islands where local conditions are favourable (e.g., hatch 2002; levermann & tøttrup 2007; lewis et al. 2013), and our observations of banded ross’s gulls suggest that individuals move between nesting islands from year to year and probably also skip breeding seasons in response to local conditions (unpubl. data). in some years, large numbers of adult red phalaropes and brant congregating in feeding flocks at some island sites (table 2) during the middle of the breeding season probably indicate widespread breeding deferral or failure by these species at the regional level (macdonald et al. 1998; latour et al. 2005). ground-nesting seabirds in the queens channel area are particularly dependent on ready access to open water to forage. in 2012, the distribution of open water (i.e., polynyas) during surveys was clearly different than predictions based on the polynya centres derived from hannah et al. (2009), which would influence the suitability of neighbouring islands for nesting birds. since ground-nesting marine birds in the high arctic appear to be plastic in their fidelity to specific breeding sites within a larger region, and are strongly influenced by interannual fluctuations in ice cover and its effect on both food availability and predation risk (egevang et al. 2004; egevang & frederiksen 2011; maftei et al. 2012), future surveys in similar habitat would likely benefit from using current satellite imagery of sea ice and snow cover to prioritize survey targets based on local conditions at the time that surveys are being conducted. detectability is a major factor that limits the accuracy of estimates of regional populations of some groundnesting species. some species can be difficult to detect even during ground-based surveys, and are probably drastically under-represented in aerial surveys. for example, female eiders are highly cryptic and may remain undetected on their nests even when closely approached on foot. in 2012 a one-time aerial survey of nasaruvaalik island recorded approximately 200 common eiders, and daily high counts made by ground-based observers over the course of the entire breeding season never exceeded 600 individuals. thorough searches, however, found 799 nests, indicating that more than 1000 individuals used this island in that year (see also falardeau et al. 2003). a substantial proportion of these individuals went undetected: 33 and 78% during ground-based and aerial surveys, respectively. highly cryptic species such as eiders are unlikely to be accurately represented in one-time surveys, and extrapolations of regional populations based on such counts would likely compound this uncertainty. even conspicuous species may be significantly overor underestimated in one-time surveys depending on their daily pattern of attendance at colony sites. for example, numbers of nesting arctic terns can be difficult to assess (egevang & frederiksen 2011), and daily average colony counts of terns conducted simultaneously by multiple observers on nasaruvaalik island sometimes differed between consecutive days by a factor of four or more, even during incubation when attendance would be presumed to be fairly consistent (m. mallory, unpubl. data). despite these challenges with survey protocols, two important results from our work were that the common eider breeding population appears to be increasing in this region, while arctic tern populations appear to be declining. increasing eiders near our site is consistent with recent population increases found in west greenland (merkel 2010). eiders from queen’s channel probably overwinter in the same region as eiders from northern west greenland (mosbech et al. 2006), so the recent declines in the numbers of eiders harvested during the winter may explain why our breeding population has increased approximately three-fold in six years. for terns, population tracking is more difficult because breeding sites can shift within a region (egevang & frederiksen 2011). indeed, our results were similar to those from greenland, where colony-specific annual variability in counts was high for small colonies, but much lower for m. maftei et al. assessing populations of ground-nesting marine birds citation: polar research 2015, 34, 25055, http://dx.doi.org/10.3402/polar.v34.25055 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25055 http://dx.doi.org/10.3402/polar.v34.25055 large colonies and for regional populations (egevang & frederiksen 2011). while numbers of terns have fluctuated at our main site (nasaruvaalik island), regionally we found a pattern of decline, consistent with other reports we have heard anecdotally from local hunters in the high arctic and along western hudson bay (m. mallory, unpubl. data), and from limited results elsewhere in nunavut (e.g., gilchrist & robertson 1999). our surveys in 2012 combined with the results obtained by mallory & gilchrist (2003) decade earlier confirm that the queens channel region is an important breeding area for a variety of species (mallory & fontaine 2004), but there is substantial interannual variability in attendance at island colonies. based on our observations, we conclude that partial surveys and extrapolations from those are unlikely to accurately reflect regional populations of ground-nesting species, and should only be used with caution in assessing regional trends in abundance. comprehensive regional surveys, while not without limitations, provide more accurate and reliable breeding population trend estimates than extrapolations based on annual monitoring of specific sites or partial samples of suitable habitat. although islands with particularly large colonies of certain species (e.g., nasaruvaalik island for arctic terns and common eiders) may prove useful as general indicators of regional populations if monitored annually, they too are subject to significant annual fluctuations in attendance, and site-specific trends should not be assumed to reflect regional ones. of the 37 islands surveyed to date in queens channel, three in particular*emikutailaq (75829?n, 97814?w), south cheyne (76829?n, 97852?w) and nasaruvaalik (76849n?, 96818?w)*support an unusually high abundance and richness of birds. nasaruvaalik island and its adjacent polynya may be one of the most important breeding and foraging sites for birds in the entire region, and supports one of the highest diversities of regularly occurring species (28) recorded at this latitude anywhere in the north american arctic. acknowledgements we thank all of the field crews who have participated in the nasaruvaalik island project since 2007. financial and logistic support was provided by the canadian wildlife federation, environment canada (canadian wildlife service, science & technology branch), natural resources canada (polar continental shelf program), the nasivvik program, the natural sciences and engineering research council, acadia university and carleton university. references birkhead t.r. & nettleship d.n. 1995. arctic fox influence on a seabird community in labrador: a natural experiment. wilson bulletin 107, 397�412. clark r.g. & shutler d. 1999. avian habitat selection: pattern from process in nest-site use by ducks? ecology 80, 272�287. danks f.s. & klein d.r. 2002. using gis to predict potential wildlife habitat: a case study of muskoxen in northern alaska. international journal of remote sensing 23, 4611�4632. egevang c. & frederiksen m. 2011. fluctuating breeding of arctic terns (sterna paradisaea) in arctic and high-arctic colonies in greenland. waterbirds 34, 107�111. egevang c., kampp k. & boertmann d. 2004. the breeding association of red phalaropes with arctic terns: response to a redistribution of terns in a major greenland colony. waterbirds 27, 406�410. falardeau g., rail j.-f., gilliland s. & savard j.-p.l. 2003. breeding survey of common eiders along the west coast of ungava bay, in summer 2000, and a supplement on other nesting aquatic birds. technical report series 405. quebec city: canadian wildlife service. gaston a.j., gilchrist h.g. & hipfner j.m. 2005. climate change, ice conditions and reproduction in an arctic nesting marine birds: brunnich’s guillemot (uria lomvia l.). journal of animal ecology 74, 832�841. gaston a.j., mallory m.l. & gilchrist h.g. 2012. populations and trends of canadian arctic seabirds. polar biology 35, 1221�1232. gilchrist h.g. & robertson g.j. 1999. population trends of gulls and arctic terns nesting in the belcher islands, nunavut. arctic 52, 325�331. hannah c.g., dupont f. & dunphy m. 2009. polynyas and tidal currents in the canadian arctic archipelago. arctic 62, 83�95. hatch j.j. 2002. arctic tern (sterna paradisaea). the birds of north america 707. philadelphia, pa: the birds of north america. hirzel a.h., hausser j., chessel d. & perrin n. 2002. ecological-niche factor analysis: how to compute habitatsuitability maps without absence data? ecology 83, 2027�2036. latour p.b., machtans c.s. & beyersbergen g.w. 2005. shorebird and passerine abundance and habitat use at a high arctic breeding site: cresswell bay, nunavut. arctic 58, 55�65. levermann n. & tottrup a.p. 2007. predator effects and bahavioral patterns in arctic terns (sterna paradisaea) and sabine’s gulls (xema sabini) during a failed breeding year. waterbirds 30, 417�420. lewis t.l., ward d.h., sedinger j.s., reed a. & derksen d.v. 2013. brant (branta bernicla). in a. poole (ed.): the birds of north america online. ithaca, ny: cornell lab of ornithology. accessed on the internet at http://bna.birds.cornell.edu/ bna/species/337 on 15 august 2014 long p.r., zefania s., french-constant r.h. & szekely t. 2008. estimating the population size of an endangered shorebird, the madagascar plover, using a habitat suitability model. animal conservation 11, 118�127. assessing populations of ground-nesting marine birds m. maftei et al. 8 (page number not for citation purpose) citation: polar research 2015, 34, 25055, http://dx.doi.org/10.3402/polar.v34.25055 http://bna.birds.cornell.edu/bna/species/337 http://bna.birds.cornell.edu/bna/species/337 http://www.polarresearch.net/index.php/polar/article/view/25055 http://dx.doi.org/10.3402/polar.v34.25055 macdonald s. 1978. first breeding record of ross’s gull in canada. proceedings of the colonial waterbird group 2, 16. macdonald s.d., reed a. & o’briain m. 1998. breeding, moulting and site fidelity of brant (branta bernicla) on bathurst and seymour islands in the canadian high arctic. arctic 51, 350�360. maftei m., davis s.e., jones i.l. & mallory m.l. 2012. breeding habitats and new breeding locations for ross’s gull (rhodostethia rosea) in the canadian high arctic. arctic 65, 283�288. mallory m.l., boadway k.a., davis s.e. & maftei m. 2011. breeding biology of sabine’s gull (xema sabini) in the canadian high arctic. polar biology 35, 335�344. mallory m.l. & fontaine a.j. 2004. key marine habitat sites for migratory birds in nunavut and the northwest territories. occasional paper 109. ottawa: canadian wildlife service. mallory m.l. & forbes m.r. 2007. does sea ice constrain the breeding schedules of high arctic northern fulmars? condor 109, 894�906. mallory m.l. & gilchrist h.g. 2003. marine birds breeding in penny strait and queens channel, nunavut, canada. polar research 22, 399�403. meltofte h. 2001. wader population censuses in the arctic: getting the timing right. arctic 54, 367�376. merkel f.r. 2010. evidence of recent population recovery in common eiders breeding in western greenland. journal of wildlife management 74, 1869�1874. moe b., stempniewicz l., jakubas d., angelier f., chastel o., dinessen f., gabrielsen g.w., hanssen f., karnovsky n.j., ronning b., welcker j., wojczulanis-jakubas k. & bech c. 2009. climate change and phenological responses of two seabird species breeding in the high-arctic. marine ecology progress series 393, 235�246. mosbech a., gilchrist g., merkel f., sonne c., flagstad a. & nyegaard h. 2006. year-round movements of northern common eiders somateria mollissima borealis breeding in arctic canada and west greenland followed by satellite telemetry. ardea 94, 651�665. nettleship d.n. 1973. seabird colonies and distributions around devon island and vicinity. arctic 27, 95�103. smith p.a., elliott k.h., gaston a.j. & gilchrist h.g. 2010. has early ice clearance increased predation on breeding birds by polar bears? polar biology 33, 1149�1153. stirling i. 1997. the importance of polynyas, ice edges, and leads to marine mammals and birds. journal of marine systems 10, 9�21. m. maftei et al. assessing populations of ground-nesting marine birds citation: polar research 2015, 34, 25055, http://dx.doi.org/10.3402/polar.v34.25055 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25055 http://dx.doi.org/10.3402/polar.v34.25055 doi:10.3402/polar.v31i0.11075 r e s e a r c h / r e v i e w a r t i c l e leadership in politics and science within the antarctic treaty john r. dudeney1 & david w.h. walton2 1 10 church lane, wilburton, cambridgeshire, cb6 3rq, uk 2 british antarctic survey, natural environment research council, high cross, madingley road, cambridge cb3 0et, uk keywords governance; claimant states; antarctic policy; scientific publications. correspondence david w.h. walton, british antarctic survey, natural environment research council, high cross, madingley road, cambridge cb3 0et, uk. e-mail: dwhw@bas.ac.uk abstract for over 50 years the antarctic has been governed through the antarctic treaty, an international agreement now between 49 nations of whom 28 consultative parties (cps) undertake the management role. ostensibly, these parties have qualified for their position on scientific grounds, though diplomacy also plays a major role. this paper uses counts of policy papers and science publications to assess the political and scientific outputs of all cps over the last 18 years. we show that a subset of the original 12 treaty signatories, consisting of the seven claimant nations, the usa and russia, not only set the political agenda for the continent but also provide most of the science, with those cps producing the most science generally having the greatest political influence. none of the later signatories to the treaty appear to play a major role in managing antarctica compared with this group, with half of all cps collectively producing only 7% of the policy papers. although acceptance as a cp requires demonstration of a substantial scientific programme, the treaty has no formal mechanism to review whether a cp continues to meet this criterion. as a first step to addressing this deficiency, we encourage the cps collectively to resolve to hold regular international peer reviews of their individual science programmes and to make the results available to the other cps. antarctica is one of few areas of the world where science is the predominant activity and where the publications it produces can be linked to policy and political initiatives in a straightforward fashion. it is governed by international agreement and managed according to the antarctic treaty and its subsidiary conventions and protocols which together comprise the antarctic treaty system (ats; jacobssen 2011). although seven nations have sovereignty claims to parts of it, and two (usa and russia) reserve rights to make claims in the future, these are currently set aside by article iv of the treaty. the treaty was signed in washington, dc, in 1959 by 12 nations, comprising the seven claimant nations plus five others who together had undertaken substantial scientific work in antarctica during the international geophysical year (1957�58). it came into force in 1961 after ratification by all signatories and now has 49 signatories (secretariat of the antarctic treaty 2012) that together represent around 65% of the world population. as the treaty developed the original parties determined a two-tier structure: those countries that acceded and conducted substantial scientific work were classed as consultative parties (cps) and those who acceded but were not active on the continent were classed as non-consultative parties. only the cps were allowed to participate in taking decisions, including the admission of new parties to the treaty and their elevation to cp status (pannatier 1994). the motivations for agreeing an antarctic treaty were political not scientific, in essence calling a truce on territorial dispute and preventing the militarization of antarctica, but the centrality of science is enshrined in the heart of the treaty (scully 2011). it is explicit in article ii: ‘‘freedom of scientific investigation in antarctica and cooperation to that end as applied during the international geophysical year, shall continue, subject to the provisions of the present treaty.’’ the fundamental purpose of the ats is therefore to protect the (page number not for citation purpose) polar research 2012. # 2012 j.r. dudeney & d.w.h. walton. this is an open-access article distributed under the terms of the creative commons attributionnoncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2012, 31, 11075, doi: 10.3402/polar.v31i0.11075 http://www.polarresearch.net/index.php/polar/article/view/11075 continent, and associated islands south of 608s, as a region of peace and science. the protocol on environmental protection to the antarctic treaty (pep), signed in 1991 and in force from 1998, introduced a very strict environmental management regime aimed at minimizing human impact upon the continent whilst reaffirming the priority of science there. the pep included the requirement to create a new advisory body for the ats: the committee for environmental protection (cep), which came into being in tromsø in 1998. the treaty allows any nation with an interest in antarctica to join, but is silent on the procedure by which they may achieve consultative status. it simply says that only those (the cps) that can demonstrate that they are carrying out ‘‘substantial scientific research activity such as the establishment of a research station or the dispatch of a scientific expedition’’ (paragraph 2 of article ix of the treaty) can participate in decision making. the definition of ‘‘substantial scientific research’’ was left deliberately vague initially, but when in 1977 poland applied to join a procedure was needed. this was developed at a special antarctic treaty consultative meeting and required the applicant to notify the depositary government (the usa) and provide information on its programmes, especially the scientific ones. the depositary government then circulated the information for comment by the other cps and the government hosting the next atcm then convened a special antarctic treaty consultative meeting at the start of the next meeting where the application was discussed and a decision taken. poland had included the establishment of an overwintering station as part of its bid. from then on the expectation was that such a station should be part of a bid, though the general guidelines (brazil ministry of external relations 1987: paragraph 49) formulated by the cps in 1987 only required a full description of current planned scientific programmes and of the planned means for carrying out the planned programme. in 1990 the netherlands successfully made the case not to establish its own station on environmental grounds when it became a cp, planning to work with other countries to utilize spare capacity on their stations on an agreed basis (pannatier 1994). though the cps do judge suitability on the basis of the criteria, less tangible political factors, perhaps having more to do with wider diplomatic issues than antarctica, also appear to play a significant part. there is no formal mechanism within the treaty for reviewing whether an existing cp continues to meet the criterion although at least one international lawyer believes that consultative status could be formally lost if research ceases (auburn 1979). however, since the ats works through consensus it seems highly unlikely that a cp would join a consensus calling for itself to be ejected! the formal business of the at is conducted only at annual meetings known as antarctic treaty consultative meetings (atcms) or occasional special atcms. all decision making is by consensus of the cps. for the first 16 years membership was limited to the original 12 signatories, with little apparent incentive for other countries to join. however, two factors*the attempt by the parties to agree on a convention for the management of antarctic mineral resources, and the possibility of conducting a review of the treaty itself after 30 years* stimulated other countries to join and achieve consultative status. matters for discussion at the atcm are raised either in the form of working papers (wps), which are translated into the four treaty languages and require debate and action, or in information papers (ips) that are informative only and are neither normally translated nor necessarily discussed. all cps and the three observers*the scientific committee on antarctic research (scar), the commission for the conservation of antarctic marine living resources (ccamlr) and the council of managers of national antarctic programs (comnap)*can table wps whilst invited experts, such as the international association of antarctic tour operators (iaato) and the antarctic and southern ocean coalition (asoc), can only table ips. the ats is undoubtedly a very successful regime for the governance of antarctica and for fostering scientific research there. yet there have been few attempts to assess how well it is working and how cps individually and collectively lead and engage in its business. recently there have been bibliometric studies of the various parties (dastidar & persson 2005; dastidar 2007; walton 2010). however, it seems that there has not been a published study of leadership and engagement within table 1 counting rules for scoring the contribution by party to each antarctic treaty consultative meeting (atcm) policy paper. counting case count single party, single target (either atcm or cep a ) scores 1 single party, targeted to both cep and atcm scores 0.5 to each target two parties, single target scores 0.5 each party two parties, two targets scores 0.25 to each target for each party multiple (n) parties, one target first named scores 0.5, others each score 0.5/(n �1) multiple (n) parties, two targets first named scores 0.25 for each target others each score 0.25/(n �1) to each target acommittee for environmental protection. leadership within the antarctic treaty j.r. dudeney & d.w.h. walton 2 (page number not for citation purpose) citation: polar research 2012, 31, 11075, doi: 10.3402/polar.v31i0.11075 http://www.polarresearch.net/index.php/polar/article/view/11075 the business of the atcm since 1971 (hanevold 1971), although there have been various attempts to look at the political drivers for each of the cps (rowland 1988; dodds 1997). nor has there been any study of how a cp’s political engagement is related to its scientific track record in antarctic research. in this paper we describe a quasiquantitative method for estimating leadership within the at, use this to compare and contrast the performance of the parties, and finally, bring these results together with bibliometric measures of scientific output. our hypothesis is that the number of wps and ips, and the relative mix of such, that a party puts forward to atcms over a period of several years is a measure of that party’s degree of leadership and engagement within the at. we recognize that this does not provide a comprehensive measure, firstly because cps also engage by debating/revising/blocking proposals, and secondly because we have not sought to analyse the content of individual wps or ips. however, we do contend that our approach does provide a very good first order measure from which significant conclusions can be drawn. in making this analysis we have opted to concentrate on the period from 1992 onwards since the pep was signed in 1991 and came into force in 1998, providing the opportunity to compare and contrast the period of preparation to 1997 (pre-pep) with the period from 1998 onwards (post-pep). also, the number of cps does not change significantly through the period (only two parties have achieved cp status since 1992: bulgaria in 1998 and ukraine in 2004) and accurate data on paper attributions are available. methods it is necessary to adopt some simple counting rules to take account of papers co-authored by several parties, and also for the post-pep period papers that are targeted at either the cep or the atcm (plenary or other working groups) or sometimes at both. since, in the case of multiple party authorship, it is usual to list parties alphabetically our counting scheme probably disadvantages such parties as the usa, uk and scar in comparison with argentina, australia and asoc, but we believe such bias is small. since 1998, when the pep came into force, all of the ips and wps presented at each atcm are publically available in full on the website of the secretariat of the antarctic treaty. pre-pep, we have relied on data amassed by uk members of the scar delegation to the atcm and tabulations of papers available in the annual reports from atcms. the data on peer-reviewed scientific publications are abstracted from web of knowledge (http://wok.mimas. ac.uk/) using ‘‘antarct*’’ as the keyword, following the methods of earlier work by dastidar & persson (2005). we also recognize that such a simple selector will disadvantage those science papers from antarctica dealing with global phenomena such as cosmology, magnetics, ionospherics and sun�earth interactions where the keyword is often not included in the title, abstract or keywords and this is likely to affect at most a small number of countries, particularly australia, uk and usa. results and discussion in the distribution of the total numbers of wps (snwp) produced by each party for the whole period from 1992 to 2010 (fig. 1) the uk stands out as the strongest performer overall, closely followed by new zealand and then australia. these three cps form an obvious leadership group ahead of all others and together they have produced 42% of all wps. all are claimant states, all have a long association with antarctic affairs, the uk in particular having been the leading nation in the early expeditions of discovery to antarctica. the top ten parties consist of all seven claimants, the usa, russia (who both reserve rights to make claims) and scar. the claimants produce 65% of wps whilst all 10 parties together produce 82% of all wps. if both ips (snip) and wps are aggregated for the whole period 1992�2010 (not shown) then the picture remains the same for the top three contributors, but for the top 10, two of the claimant cps (france and norway) are replaced by iaato and asoc, reflecting their great contribution in ips. wps clearly carry much more weight than ips in terms of demonstrating engagement in the treaty, as the atcm rules require wps to be discussed whilst ips are discussed only on request. we have therefore compared what emphasis parties put on the one compared with the other, using a normalized index, rw, for each party to demonstrate this, where rw � �x nwp � x nip � = �x nwp � x nip � thus, if a party produces more wps than ips overall then 0brw51; while if it produces more ips than wps then �15rwb0. figure 2 gives the results of this analysis for the period after the pep came into force, where the parties are ordered with respect to snwp (largest at the bottom), and cep and atcm counts are aggregated. only four parties have consistently generated more wps than ips. all four are claimants and it is notable that the j.r. dudeney & d.w.h. walton leadership within the antarctic treaty citation: polar research 2012, 31, 11075, doi: 10.3402/polar.v31i0.11075 3 (page number not for citation purpose) http://wok.mimas.ac.uk/ http://wok.mimas.ac.uk/ http://www.polarresearch.net/index.php/polar/article/view/11075 two cps that have produced the most wps overall fall in this group. also, with but few exceptions, the emphasis put on producing wps compared with ips grows with the number of wps produced. there are marked differences between the behaviour exhibited by some parties before and after the pep came into force in 1998, as illustrated by fig. 3. new zealand, argentina and the uk have a very consistent behaviour preand post-pep, australia has become relatively more active post-pep whilst chile shows the opposite behaviour. the usa, norway, france and russia have been much more engaged post-pep than pre-pep. notably, the usa produced very few wps indeed in the pre-pep period. scar, germany and the netherlands seem to have become less engaged. in the case of scar, this probably reflects the fact that its role within the treaty has been changed by the increasing activities of the cep post-pep. to the extent that production of wps does represent leadership and engagement, none of the nations that acceded to the treaty after the original 12 nations has made any major impact compared with that of the seven claimant nations, the usa and russia. to that extent the antarctic treaty remains the preserve of this rather select group, all of whom have either long-term connections, claims, strong wider geopolitical or major scientific interests, or all four of these, to spur them to give relatively high priority to the treaty. the ‘‘imperial three’’ of uk, australia and new zealand are clearly dominant, echoing an earlier historical context. in 1919 the british politician leo amery wrote on behalf of the british government to the governors general of australia and new zealand proposing that the british empire should adopt a policy of territorial claims that would bring the whole of antarctica under the control of the empire (dudeney & walton 2011). this policy was vigorously pursued in the 1920s and into the 1930s, and though not ultimately fully successful, did bring most of the continent within the empire. it is hence notable that these three cps have dominated the business of the ats consistently over the period, though they nowadays do not necessarily speak with one voice! the 14 least involved cps contribute fewer than 7% of the wps. this is an interestingly heterogeneous group comprising both developed european democracies (finland, spain, sweden), former communist european states (bulgaria, poland, ukraine), two of the largest fig. 1 total sum of working papers produced by each of the parties to the antarctic treaty for the period 1992�2010, ordered by descending total number from the left-hand side of the plot. the figure includes the following abbreviations: scar (scientific committee on antarctic research), comnap (council of managers of national antarctic programs), ccamlr (commission for the conservation of antarctic marine living resources), asoc (antarctic and southern ocean coalition) and iaato (international association of antarctic tour operators). leadership within the antarctic treaty j.r. dudeney & d.w.h. walton 4 (page number not for citation purpose) citation: polar research 2012, 31, 11075, doi: 10.3402/polar.v31i0.11075 http://www.polarresearch.net/index.php/polar/article/view/11075 economies in the world (china, japan), major emerging economies (brazil, korea), three small south american states (ecuador, peru, uruguay) and one of the original 12 signatories (south africa). of the observers, scar is clearly the leader and it should be noted that it was established prior to the birth of the treaty and has always been its major science advisor (walton 2011; walton & clarkson 2011). comnap (fowler 2000) is a consistent contributor in the top half of the parties to the treaty, but perhaps has not had as much impact as its members might have hoped when it separated from scar in 1988. ccamlr sees its role at treaty meetings as one of liaison and its input of papers reflects this passive approach. we have given a broad picture of the cps performance on the diplomatic stage. how does this compare with their commitment to, and productivity from, their scientific programmes in antarctica, noting that they must demonstrate a ‘‘substantial scientific research activity’’? the number of peer-reviewed publications produced by a cp is compared with its number of wps in fig. 4. generally, the more engaged a cp is in the diplomacy the greater will be its output of science* which is reassuring. however, this is true only to the zeroth order and given the very disparate nature of the fig. 2 normalized plot comparing production of working papers with that of information papers for the period 1998�2010. see the text for the definition of the index rw. the figure includes the following abbreviations: iaato (international association of antarctic tour operators), asoc (antarctic and southern ocean coalition), ccamlr (commission for the conservation of antarctic marine living resources), comnap (council of managers of national antarctic programs) and scar (scientific committee on antarctic research). j.r. dudeney & d.w.h. walton leadership within the antarctic treaty citation: polar research 2012, 31, 11075, doi: 10.3402/polar.v31i0.11075 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/11075 cps in terms of gross domestic product, population, level of development etc. this is hardly surprising. the criterion to become and remain a cp is the demonstration of substantial scientific research activity. this is not a quality measure, rather it addresses quantity but in an ill-defined way. figure 4 shows that some parties produce almost no publications*can this be fairly represented as substantial? furthermore, as the dastidar & persson (2005) results show, some cps have a lower scientific output than several of the non-consultative parties, and even nations who are not parties at all. though the rules of the treaty do contain a rather general and ill-defined mechanism by which the cps must reach consensus on whether a candidate cp qualifies, once qualified there is no mechanism for assessing whether the criterion continues to be met. as we have already noted, even if there was, consensus decision making means that there can never be a procedure for expelling a cp on the grounds that it no longer has a substantial programme. even so, it seems fig. 3 normalized plot of the annual average productivity (ap) of a party compared with the overall average (aa), presented separately for the period up to and including 1997 (pre-pep) and from 1998 onwards (post-pep). the figure shows a normalized index, ra, where ra�(ap�aa)/(ap�aa), for each of the parties ordered with respect to snwp (largest at the bottom), with filled bars for the post-pep period and open bars for the pre-pep period. a value of rab0 indicates that the party concerned is performing less well than the average, whilst ra�0 shows a better than average performance. the figure includes the following abbreviations: iaato (international association of antarctic tour operators), asoc (antarctic and southern ocean coalition), ccamlr (commission for the conservation of antarctic marine living resources), comnap (council of managers of national antarctic programs) and scar (scientific committee on antarctic research). leadership within the antarctic treaty j.r. dudeney & d.w.h. walton 6 (page number not for citation purpose) citation: polar research 2012, 31, 11075, doi: 10.3402/polar.v31i0.11075 http://www.polarresearch.net/index.php/polar/article/view/11075 very strange that the ats, which apparently prides itself on its bedrock of science, has no formal mechanism for critical review of cps research performance. there has been at least one suggestion at an atcm that scar should be requested to review the science undertaken by all parties in the antarctic but scar has resolutely refused to accept such a potentially divisive activity (secretariat of the antarctic treaty 2005, paragraphs 183b and 192). several cps have had independent international reviews of their antarctic programmes carried out both to inform their policy makers and improve their science quality, but, as far as we are aware, only finland has ever made the results of such a review public (dudeney et al. 2006) and explicitly brought those results to an atcm (finland 2007). this prompted a reevaluation of finland’s research objectives which was the subject of a further paper at the following atcm (finland 2008). we encourage the ats to recommend that all cps should have regular international peer reviews of their programmes and should make the results available to the other cps. as a minimum, leading cps could voluntarily follow finland’s lead to encourage the others. in a first attempt to assess the extent of the possible costs associated with leadership in fig. 5 the data are normalized using gross domestic product figures for 2010. this presents a very different distribution. there is still a clear correlation between scientific productivity and wp productivity, but it is now possible to draw some initial conclusions about the value for money of the investment in antarctica for different cps’ performance compared with their general world ranking. new zealand stands out, putting great priority on full engagement in antarctic affairs (but benefitting greatly from its close association with us logistics). it leads a small group of countries (chile, argentina, australia, the uk and norway), all of them claimants, that do the same. by contrast the usa is now way down the pecking order. china sits at the very bottom left hand corner of the plot. however, this may be giving a false picture as china’s gross domestic product and its production of science papers has grown dramatically over the period covered, a trend which shows every sign of continuing. we conclude that at present the treaty remains effectively a select club dominated by the claimant fig. 4 log/log plot of the number of working papers produced by all consultative parties compared with their output of science papers from 1992 to 2010. j.r. dudeney & d.w.h. walton leadership within the antarctic treaty citation: polar research 2012, 31, 11075, doi: 10.3402/polar.v31i0.11075 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/11075 nations and the cold war warriors (usa and russia), and that the return on the investment in antarctic activities in terms of significant science or political initiatives seem lacking for several countries. further more detailed investigations seem warranted to determine how scientific investment is related to subject leadership, what are the key science papers and their effects, what regional groupings (for example south american or european countries) can do to develop particular political ideas and how antarctic science relates to earth system science in an increasingly fragile world. acknowledgements we are grateful to the leverhulme trust, the transantarctic association and the commissioner for british antarctic territory for grants to enable us to carry out this research. the comments of two anonymous reviewers are gratefully acknowledged. references auburn f.m. 1979. consultative status under the antarctic treaty. comparative international law quarterly 28, 514�522. brazil ministry of external relations 1987. final report of the fourteenth antarctic treaty consultative meeting. buenos aires: brazil ministry of external relations. dastidar p. 2007. national and institutional productivity and collaboration in antarctic science: an analysis of 25 years of journal publications (1980�2004). polar research 26, 175�180. dastidar p. & persson o. 2005. mapping the global structure of antarctic research vis-a-vis antarctic treaty system. current science 89, 1552�1554. dodds k. 1997. geopolitics in antarctica: views from the southern ocean rim. chichester: john wiley. dudeney j.r., peltier w.r. & navarro f.j. 2006. antarctic research in finland 1998�2005. international evaluation. helsinki: academy of finland. dudeney j.r. & walton d.w.h. 2011. from scotia to ‘operation tabarin’*developing british policy for antarctica. polar record, doi: 10.1017/s0032247411000520. fig. 5 log/log plot of the number of working papers (wps) produced by all consultative parties compared with their output of science papers from 1992 to 2010, normalized by the 2010 gross domestic product (gdp) of the consultative parties. gdp data are for 2010 (world bank 2011) and are in usd. leadership within the antarctic treaty j.r. dudeney & d.w.h. walton 8 (page number not for citation purpose) citation: polar research 2012, 31, 11075, doi: 10.3402/polar.v31i0.11075 http://www.polarresearch.net/index.php/polar/article/view/11075 finland 2007. antarctic research in finland 1998�2005. international evaluation. information paper 3. xxx antarctic treaty consultative meeting. 30 april�11 may, new delhi. finland 2008. finland’s antarctic research strategy. information paper 40. xxxi antarctic treaty consultative meeting. 12�23 june 2006, edinburgh. fowler a.n. 2000. comnap, the national managers in antarctica. baltimore: american literary press. hanevold t. 1971. the antarctic treaty consultative meetings*form and procedure. cooperation and conflict 6, 183�199. jacobsson m. 2011. building the international legal framework for antarctica. in p. berkman et al. (eds.): science diplomacy: antarctica, science and the governance of international spaces. pp. 1�15. washington, dc: smithsonian institution scholarly press. pannatier s. 1994. acquisition of consultative status under the antarctic treaty. polar record 30, 123�129. rowland j.r. 1988. the treaty regime and the politics of the consultative parties. in c.c. joyner & s.k. chopra (eds.): the antarctic legal regime. pp. 11�31. dordrecht: martinus nijhoff. scully t. 2011. the development of the antarctic treaty system. in p. berkman et al. (eds.): science diplomacy: antarctica, science and the governance of international spaces. pp. 29�38. washington, dc: smithsonian institution scholarly press. secretariat of the antarctic treaty 2005. final report of the twenty-eighth antarctic treaty consultative meeting. buenos aires: secretariat of the antarctic treaty. secretariat of the antarctic treaty 2012. the antarctic treaty. accessed on the internet at http://www.ats.aq/e/ats.htm on 27 february 2012 walton d.w.h. 2010. trends and patterns in antarctic science. in s. campbell & e. maloney (eds.): polar libraries colloquy 2008. currents of change. the future of polar information. pp. 163�176. edmonton: cci press and the canadian circumpolar library, university of alberta. walton d.w.h. 2011. the scientific committee on antarctic research and the antarctic treaty. in p. berkman et al. (eds.): science diplomacy: antarctica, science and the governance of international spaces. pp. 73�88. washington, dc: smithsonian institution scholarly press. walton d.w.h. & clarkson p.d. 2011. science in the snow: 50 years of international collaboration in antarctica. cambridge: scientific committee on antarctic research. world bank 2011. gross domestic product 2010. world development indicators database. accessed on the internet at http://databank.worldbank.org/databank/download/gdp. pdf in july 2011. j.r. dudeney & d.w.h. walton leadership within the antarctic treaty citation: polar research 2012, 31, 11075, doi: 10.3402/polar.v31i0.11075 9 (page number not for citation purpose) http://www.ats.aq/e/ats.htm http://databank.worldbank.org/databank/download/gdp.pdf http://databank.worldbank.org/databank/download/gdp.pdf http://www.polarresearch.net/index.php/polar/article/view/11075 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 20%) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.0000 /colorconversionstrategy /cmyk /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 300 /colorimageminresolutionpolicy /ok /downsamplecolorimages true /colorimagedownsampletype /bicubic /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 300 /grayimageminresolutionpolicy /ok /downsamplegrayimages true /grayimagedownsampletype /bicubic /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile () /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname () /pdfxtrapped /false /createjdffile false /description << /ara <feff06270633062a062e062f0645002006470630064700200627064406250639062f0627062f0627062a002006440625064606340627062100200648062b062706260642002000410064006f00620065002000500044004600200645062a064806270641064206290020064406440637062806270639062900200641064a00200627064406450637062706280639002006300627062a0020062f0631062c0627062a002006270644062c0648062f0629002006270644063906270644064a0629061b0020064a06450643064600200641062a062d00200648062b0627062606420020005000440046002006270644064506460634062306290020062806270633062a062e062f062706450020004100630072006f0062006100740020064800410064006f006200650020005200650061006400650072002006250635062f0627063100200035002e0030002006480627064406250635062f062706310627062a0020062706440623062d062f062b002e0635062f0627063100200035002e0030002006480627064406250635062f062706310627062a0020062706440623062d062f062b002e> /bgr <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> /chs <feff4f7f75288fd94e9b8bbe5b9a521b5efa7684002000410064006f006200650020005000440046002065876863900275284e8e9ad88d2891cf76845370524d53705237300260a853ef4ee54f7f75280020004100630072006f0062006100740020548c002000410064006f00620065002000520065006100640065007200200035002e003000204ee553ca66f49ad87248672c676562535f00521b5efa768400200050004400460020658768633002> /cht <feff4f7f752890194e9b8a2d7f6e5efa7acb7684002000410064006f006200650020005000440046002065874ef69069752865bc9ad854c18cea76845370524d5370523786557406300260a853ef4ee54f7f75280020004100630072006f0062006100740020548c002000410064006f00620065002000520065006100640065007200200035002e003000204ee553ca66f49ad87248672c4f86958b555f5df25efa7acb76840020005000440046002065874ef63002> /cze <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> /dan <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> /deu <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> /esp <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> /eti <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> /fra <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> /gre <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> /heb <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> /hrv (za stvaranje adobe pdf dokumenata najpogodnijih za visokokvalitetni ispis prije tiskanja koristite ove postavke. stvoreni pdf dokumenti mogu se otvoriti acrobat i adobe reader 5.0 i kasnijim verzijama.) /hun <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> /ita <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> /jpn <feff9ad854c18cea306a30d730ea30d730ec30b951fa529b7528002000410064006f0062006500200050004400460020658766f8306e4f5c6210306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103055308c305f0020005000440046002030d530a130a430eb306f3001004100630072006f0062006100740020304a30883073002000410064006f00620065002000520065006100640065007200200035002e003000204ee5964d3067958b304f30533068304c3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /kor <feffc7740020c124c815c7440020c0acc6a9d558c5ec0020ace0d488c9c80020c2dcd5d80020c778c1c4c5d00020ac00c7a50020c801d569d55c002000410064006f0062006500200050004400460020bb38c11cb97c0020c791c131d569b2c8b2e4002e0020c774b807ac8c0020c791c131b41c00200050004400460020bb38c11cb2940020004100630072006f0062006100740020bc0f002000410064006f00620065002000520065006100640065007200200035002e00300020c774c0c1c5d0c11c0020c5f40020c2180020c788c2b5b2c8b2e4002e> /lth <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> /lvi <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> /nld (gebruik deze instellingen om adobe pdf-documenten te maken die zijn geoptimaliseerd voor prepress-afdrukken van hoge kwaliteit. de gemaakte pdf-documenten kunnen worden geopend met acrobat en adobe reader 5.0 en hoger.) /nor <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> /pol <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> /ptb <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> /rum <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> /rus <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> /sky <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> /slv <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> /suo <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> /sve <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> /tur <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> /ukr <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> /enu (use these settings to create adobe pdf documents best suited for high-quality prepress printing. created pdf documents can be opened with acrobat and adobe reader 5.0 and later.) >> /namespace [ (adobe) (common) (1.0) ] /othernamespaces [ << /asreaderspreads false /cropimagestoframes true /errorcontrol /warnandcontinue /flattenerignorespreadoverrides false /includeguidesgrids false /includenonprinting false /includeslug false /namespace [ (adobe) (indesign) (4.0) ] /omitplacedbitmaps false /omitplacedeps false /omitplacedpdf false /simulateoverprint /legacy >> << /addbleedmarks false /addcolorbars false /addcropmarks false /addpageinfo false /addregmarks false /convertcolors /converttocmyk /destinationprofilename () /destinationprofileselector /documentcmyk /downsample16bitimages true /flattenerpreset << /presetselector /mediumresolution >> /formelements false /generatestructure false /includebookmarks false /includehyperlinks false /includeinteractive false /includelayers false /includeprofiles false /multimediahandling /useobjectsettings /namespace [ (adobe) (creativesuite) (2.0) ] /pdfxoutputintentprofileselector /documentcmyk /preserveediting true /untaggedcmykhandling /leaveuntagged /untaggedrgbhandling /usedocumentprofile /usedocumentbleed false >> ] >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice reindeer pastoralism in modem siberia: research and survival during the time of crash igor krupnik in many areas across siberia, the reindeer herding economy of the native people went into a deep recession during the post-soviet transition of the 1990s. however, as a larger cross-section of data indicates, the reindeer stock decline is not a universal phenomenon. nor is the present-day crisis in native siberian herding economies an unprecedented event, as pastoralists did suffer tremendously in “traditional times”, due to the devastating epizootics and other natural disasters, and even more so, during the soviet-induced collectivization. while such a historical review by no means diminishes the scale of the present-day crisis in native herding economies, it helps to identify both the experience and traditional adaptations once used by the native siberians during the previous times of hardship. of those, the most efficient were: maintaining cultural and ecological diversity in local herding systems; the ability to shift quickly between nomadic and sedentary subsistence patterns; and preservation of the indigenous herding tradition and the ‘‘core” nomadic population as the invaluable source of cultural knowledge, technological expertise, and of domestic reindeer stock for ultimate recovery. the modern situation in siberia, in fact, favours increased local diversity and helps to produce a steady stream of new “winners” as well as new “losers.” this new experience has to be comprehensively documented, to produce both a reliable general overview and a detailed summary of the specific regional and local transitions. i. krupnik, arctic studies center, srnithsonian institution, washington, d. c. 20560, usa. several recent surveys and first-hand reports indicate that the reindeer herding economy of siberian indigenous people is in a deep recession if not in utmost crisis. its very survival and continuity is reportedly threatened, due to severe economic hardships, demise of reindeer stock and lack of financial support from russia’s federal and local agencies. herders and their families are abandoning the tundra and forest camps for villages, in search for any source of employment, health services as well as for the mere sense of belonging and stability. this process is amply documented across siberia by native leaders, journalists, and visiting researchers alike (e.g. ettyryntina & koryagin 1996; abryutina 1997; gray 1997; startsev 1997; williams 1997; csonka 1998; khrushchev & klokov 1998; klokov 1998; kladkin 1999; vakhtin & krupnik 1999). in many areas the situation can be properly labelled “the great reindeer crash.” while the entire reported domestic reindeer stock in russia has dwindled from 2260 4000 in 1991 to barely 1592000 in 1997 (khrushchev & klokov 1998: 13), many regions are in a true downward spiral. chukotka (chukchi autonomous area) witnessed its domestic reindeer stock slashed from 4 1 0 0 0 0 to fewer than 180000 (vedomost’ 1996; csonka 1998; etylen 1999); the sakha republic (yakutia from 360 000 to 200 000 (alexeev 1999); the taimyr area from 120 000 to 44 000 (klokov 1998). several herding cooperatives, local com munities, administrative districts, and whole indigenous nations, like the ket and the nganasan, have lost all or most of their reindeer husbandry (vedomost’ 1996; khrushchev & klokov 1998; klokov 1998). a s reindeer stocks and its com mercial production declined, supplies dried out. herders’ wages have not been paid in months and years, and the prices for major food commodities across the russian arctic skyrocketed (ziker krupnik 2000: polar research 19(1), 49-56 49 1998; kladkin 1999). in most of the siberian herding communities health service is almost non existent and violent death, alcoholism and other health risks are on the rise (abryutina 1998; gray 1998; sukhaya 1999). in fact, the proceedings of this workshop, which aimed at producing a long term research agenda for interdisciplinary studies in siberian reindeer husbandry, may look more like a eulogy. this volume documents what was rightly called by russian reindeer researcher vitaly zadorin (1999) “the beginning of the end of yet another branch of human civilization.” there is hardly an easy path toward designing an interdisciplinary and international “research planning” strategy under such harsh circum stances, from both logistical and ethical points of view. research is clearly not the first priority-to people and communities who are on the brink of survival. therefore, any scientific study to be designed and accomplished under the current state of “crash” in siberian reindeer industry has to deal with two basic imperatives. first, it should provide adequate documentation of the situation “on the ground” (whether catastrophic or not), from ecological and human perspective. and second, every local survey has to address (at least, implicitly) a critical moral question: is there any place or a strategy for siberian reindeer herders of today to turn to in search of economic and cultural survival? i believe the situation may still be approached with a reserved optimism, particularly in certain areas, based upon the historical record of the endurance and adaptability of the siberian indigenous people. indigenous reindeer economies in siberia traditionally, native subsistence economies across the russian arctic and siberia were arranged under some sort of nomadic-sedentary continuum. it supported an amazing diversity in northern lifestyles, cultural patterns and modes of resource utilization (see krupnik 1989, 1993: 210-215). the two opposing extremes of the spectrum were created by sharply contrasting subsistence strate gies in terms of their type of procurement and responses to the environmental change. the sedentary strategy was orientated toward intense exploitation of relatively small selected coastal and riverine niches, with high and usually predictable local concentrations of many valuable subsistence resources. the contrasting mobile/ nomadic strategy followed a pattern of population dispersion and regular rotation of seasonal hunting ranges and/or reindeer pastures. it allowed to occupy much larger environmental niches, where subsistence resources were patchy, unstable or of short duration in course of the annual cycle. most of the indigenous nations that are at the focus of this volume have adopted the latter strategy of year-round mobile/nomadic subsis tence, with domestic reindeer or caribou as its prime resource. this, again, included a whole spectrum of ecological and/or cultural patterns based upon the growing role of domesticated (that is, herded) versus wild or feral (that is, hunted) races of r . tarandus in human economy. at the one end, there were native groups like the iiiupiat, innu, dogrib and gwich’in in north america that never developed reindeer husbandry and lived primarily by highly specialized exploitation of mobile caribou stocks. most of the tundra and the boreal forest zone in siberia was occupied by indigenous nations that matched subsistence caribou hunting with small-scale reindeer econo my (like the nganasan, dolgan, yukagir, evenk, even, ket, orok and khanty peoples). finally, there were true pastoralists, such as the “euro pean” and siberian nenets, chukchi, koryak, komi and the saami, who developed highly sophisticated and specialized reindeer industries, wherein hunting played a little role if any in the domestic economy. this typology, of course, refers to the time prior to the state-induced policies of economic modernization in siberia, scandina via and north america alike. such subsistence diversity was reportedly a product of successful cultural adjustment to the high insecurity and general resource instability of the arctic environment (krupnik 1993: 156-159). in fact, dozens of local subsistence patterns were positioned in between the two extremes of the “arctic cultural continuum”: the nomadic and the sedentary. this was determined by every local group’s range of annual mobility, distance to be covered each year andlor the number of people dependent upon reindeedcaribou as their staple economic resource. differences in residential mobility even among the nearby communities were well established and persistently maintained, both culturally and ecologically (for regional surveys see chamolusskii 1930; druri 1936; vasil’ev 1970). increase as well as decrease in 50 reindeer pastoralism in modem siberia nomadism was widely practised as an adaptive response to changing wealth in domestic reindeer stock and/or shifts in local subsistence resources. residential mobility was also affected by domi nant environmental trends that could bring hard times alternatively either to inland herders and caribou hunters or to the coastal whalers, seal hunters, and fishermen (minc 1986: 70; krupnik 1993: 210-212). human life in the arctic as it is known from elders’ memories, archaeological and historical records has been always dominated by periodic or irregular ecosystem changes. these were triggered by the alternating warming and cooling phases, occasional weather catastrophes, by game population cycles and epizootics. thus, the on going flux of arctic native residents from a (more) sedentary to (more) nomadic subsistence and vice versa was the key factor of strength and sustain ability in native economies. this amazing level of cultural and ecological diversity required fleki bility and endurance during hard times. both features are indeed amply documented by elders’ memories as well as by numerous ethnographic and archaeological records across the arctic (krupnik 1993: 210-215). cases of earlier reindeer catastrophes as we know from russian historical sources, terrible things have happened many a time to siberian indigenous hunters and herders. records of the 1800s and the early 1900s have documented devastating losses of reindeer stocks by local herders, due to the occasional weather and environmental calamities, and striking epizootics. according to numerous observers, those produced panic and were met with dreadful horror by local herders. wealthy pastoralists could be converted into herdless, sedentary paupers in a matter of days. as one witness reported, “during epizootics, reindeer die throughout the tundra in herds of thousands. enormous graveyards appear, caver nous places infected with a terrible disease . . . the herders are in a panic, and are changed overnight from wealthy people to beggars. they ride away from the dead herd on the few animals left standing on their feet, just to keep them alive” (sosunov 1925: 35 i n krupnik 1993: 153-154, m. levenson trans.). the soviet-induced modernization of the siber ian indigenous peoples and their economies triggered an even more profound and dramatic transition after 1930. the new regime espoused the ideology of collective property and labour, and it favoured rapid sedentarization by force, if necessary of the nomadic population. it elimi nated rich herders, discouraged year-round mobi lity, and launched a full-scale policy of active social engineering by closing smaller villages and family nomadic camps (forsyth 1992: 293-299; vakhtin 1994: 50-51). owners of large and medium-size herds were labelled “class enemies.” they were deliberately overtaxed, disenfran chised, forced to join collective farms, and jailed or exiled when they refused. the herders resisted by fleeing to the remotest tundra areas where they could escape the iron fist of the soviet regime. when they were unable to flee they preferred to slaughter their livestock rather than seeing them incorporated into collective herds. among the reindeer herders of northern siberia, the estimated loss of stock by 1935 was between 30 and 50%, or from 2 200 000 to less than 1 5 0 0 000 reindeer (forsyth 1989; khrushchev & klokov 1998: 7-9). this was reportedly close to or even higher than the present-day reindeer crash. the central siberian cattle and horse pastoralists, such as sakha and buryat, had slaughtered about 60% of their stock (chichlo 1981). the remaining domes tic stock was then incorporated as a common property of the state-supported collective farms (kolkhozes) and state farms (sovkhozes). following the state-run resettlement and seden tarization campaign, hundreds of smaller sites and family camps were closed; their inhabitants were forcefully relocated to larger villages or newly built modern communities. former herding camps of close relatives and long-term partners were converted into “productive brigades” (work teams), with appointed migration routes, fixed salaries, and annual production output set up by the local farm and district economic bosses. by the 1970s, the pre-soviet free mobility of herders and their former nomadic lifestyle was almost gone under the pressure of paternalistic soviet moder nization. this caused a tremendous shift of the once nomadic population primarily women, children and elders -towards sedentary village life and the wage/welfare economy. a few limited areas across siberia, such as the yamal and the gydan peninsulas, the upper kara river basin, offered rare exceptions, remaining as prime “sanctuaries” of more traditional-style family krupnik 2000: polar research 19(1), 49-56 5 1 herding (bj@rklund 1995; golovnev 1995; yoshi da 1997; golovnev & osherenko 1999). native reindeer pastoralism was declared an “archaic” and hazardous occupation, “unhealthy” for women and children, and “doomed” to be replaced by more advanced practices. tons of the former soviet propaganda literature as well as of aca demic research worked to disseminate this mes sage of blunt pressure unleashed by a powerful state against cultural traditions of its remote indigenous communities. these sad memories are often overlooked against the background of post-soviet nostalgia (even by the native people themselves, e.g. ziker 1998: 195-196, 214; kladkin 1999: 9-1 1). the true “costs-and-bene fits” record has to b e remembered for a more balanced perspective on the endurance of indigen ous herding under the soviet regime. herders’ survival strategies during the crash this historical review by no means diminishes the scale of present-day misfortunes, nor is it aimed at overlooking the dismal status of indigenous reindeer economies in siberia. it helps, however, to illuminate both the experience and the resources once used by the siberian native herders in times of hardship. those may be of critical value for the tarandus users of today. one of the most successful traditional adaptive strategies was the remarkable diversity of the northern human-reindeer systems, both cultural and ecological. the soviet state had almost succeeded in replacing this diversity by a more or less uniform herding pattern spread over the entire tundra zone of arctic russia, from the barents sea to the bering sea. it introduced large-scale, heavily subsidized, collectivized, and centrally planned reindeer industry, and it promoted this model with an iron fist. the model was based on the state allocated and prescribed local distribution of seasonal pastures and migration routes. it favoured similar practices and it used an almost uniform ratio of some 6-8 paid herders for a standard “brigade” (herding crew) in charge of a stock of 2000-2500 reindeer. this greatly diminished diversity was one of the heaviest costs of the governmental interven tion into the once “unregulated” subsistence economy. generations of local experiences, skills and cultural adaptations were ignored. recent indigenous revival in siberia followed by the collapse of the centralized state economy in 199 1-92 has, surprisingly, opened opportunities for more diversity in native reindeer herding systems, at least in certain areas. planned produc tion quotas have been abandoned. few if any mechanisms of enforcement to keep native herders within the strict designated slots of seasonal pastures and migration routes once assigned by the state agencies remain in place. since the late 1980s, major limitations on mobility and residence in tundra and boreal forest pasture lands were lifted, first and foremost for women and children who follow professional herdsmen and hunters, primarily during the summer months. this increased mobility and growing regional diversity could offer a fortuitous lift to native reindeer economies during the ongoing crash. the long-expected transformation of the post soviet reindeer industry has fostered enthusiasm in native communities, though hopes have been short livqd. the drive to decentralize or even to close the state herding farms and to reclaim reindeer property through privatization and various forms of shared ownership became extremely popular. for a few years, native leaders and local media across siberia engaged in public debates focused upon small reindeer cooperatives or family-based teams of herders (“family farms”). whichever new herding and property system eventually emerges across siberia, it will most certainly help to return women, children and elders to reindeer camps on a more permanent basis as is already happening in yamal, the lower yenisey river valley, the northern urals, and some other areas (see bj@rklund 1995; klokov 1996; golovnev & osherenko 1999). those who are to come back to the tundra will need more reindeer to become more self sufficient. this renewed focus on reindeer as a foundation for family life and a means of survival rather than a “commodity” under a state-controlled economy may be another resource to boost herders’ endurance during the crash. last but not least is the new role of the nativist grass-roots ideology that has growing influence across siberia. native (that is, traditional or “our fathers”’) values of a free life outside the settlements dominated by the outsiders and frustrated by alcoholism, unemployment and violence, have gained a renewed popularity. participation in subsistence activities and resi dence in tundra camps is coming back as the pillars of cultural continuity and ethnic pride. 52 reindeer pastoralism in modern siberia as a result of these and many other factors, a sort of a regeneration of mobile subsistence or of mixed subsistence and commercial reindeer herd ing is gradually taking place in certain areas in siberia. this is sure to transform into a greater diversity in the local herding systems (see reviews in anderson 1995: klokov 1996, 1998). while most data are still incidental, this process is of critical importance and requires special research attention and thorough statistical documentation. to the best of our knowledge, the yarnal, gydan, and the lower yenisey river valley as well as the northern sections of the sakha republic (yakutia) have the best chances to brave the calamities of the “big crash.” local survival is almost certain to b e pursued via a gradual (though highly uneven) shift toward family herding and more active “bush life,” after decades of state engineering and enforced sedentarization. in several other regions the old reindeer economy of the soviet era all but collapsed and the reindeer stock is at its lowest level on record. chukotka (chukchi autonomous area) is prob ably the hardest hit, followed by the taymyr peninsula and evenkia (evenki autonomous area; see gray 1997; startsev 1997; klokov 1998; ziker 1998). here both state-owned and cooperative herds have degenerated because of poor manage ment, poaching and direct neglect by the herders. while local people experience enormous suffering and cultural loss, the process, again, follows a fairly traditional pattern: a rapid shift to a sedentary (village) lifestyle under emergency conditions in the tundra. sedentarization may be a dreadful option; but if history is a guide then both people and reindeer may eventually return to tundra pastures when the situation improves. the old nomadic-sedentary continuum is once again offering options to optimize local economic activities and redistribute the population. this time, however, the shift toward sedentariness can hardly be called a response to environmental change but a more desperate survival strategy during an era of extreme economic instability and social deprivation. research agenda during the “time of crash’ the present-day crisis in the siberian reindeer economy poses tough ethical challenges for social and natural scientists alike. the current dismal status of herders and their stocks widespread pasture degradation, painful transition to the new “sedentism,” and the endangered legacy of the siberian “reindeer herding civilization” have to be amply documented if native cultural endurance and/or scholarship are to offer a plausible solution. for a few short years in the early 1990s many a regional siberian administration allowed tourists and other visitors almost unrestricted travel in native areas, including distant reindeer camps and herds. many researchers and journalists, western and russian alike, have enjoyed a unique experi ence of long-term contact with and sojourn among native herders, often in some of the most remote and once inaccessible places across siberia (vitebsky 1992; kwon 1993; bjarklund 1995: anderson 1996; kerttula 1996; yoshida 1997; fondahl 1998; gray 1998; takakura 1998; tuisku 1998; ziker 1998: golovnev & osherenko 1999). the bulk of our current knowledge on siberian herding communities presently comes from these foreign or joint studies rather than from the soviet ethnographies of that bygone era. while more local studies of the siberian herding communities are currently available than ever before, one of the most urgent tasks is to produce a reliable overview of the overall status of the siberian reindeer economies, something like a “state of the industry” report. a similar strategy was once advanced by the respected (soviet) “committee on the north” in the 1920s, when native siberian herders experienced even more dreadful hardships as a result of the russian revolution, civil war, and overall economic collapse (sergeev 1955: 224-228). the commit tee’s determination generated a year-round inven tory, the economic census of the polar north of 1926/27 (pokhoziaistvennaia perepis ’ 1929), that produced a unique database on almost every aspect of native subsistence activities. today, a similar overview can be produced by compiling available local reports or by an overall russian “arctic reindeer project” built of successive regional surveys in a common format. russian researchers argue in favour of both types of studies (e.g. klokov 1998), and they sure may capitalize on their excellent long-term experience and intellec tual resources. funding, though, is a key factor; hence these efforts deserve strong encouragement from and practical support by the international research community. second, ample documentation of specific re krupnik 2000: polar research 19(1), 49-56 53 gional and local transitions remains a high continuity of the siberian “reindeer civilization.” priority. the re-emerging regional and cultural as more people are forced out of herding camps by diversity in siberian reindeer economies produces economic hardship and management failures, the a steady stream of new “winners” as well as new pool of traditional subsistence knowledge, prac “losers.” it is still hard to rationalize why under tical skills, grazing and pasture experts, and generally similar political and economic systems trained stock users is shrinking. the only way to the chukchi are progressively losing reindeer keep this legacy alive is to increase its public status while the nenets steadily increase their private as an invaluable subsistence resource and an herds, often to an extent dangerous to the irreplaceable cultural and public treasure. here, ecosystem and therefore to their herding. both once again, scholars may offer critical help. types of transition as well as dozens of other local flagging public spirit and herders’ pride can be experiences may prove instructive to reindeer boosted via outreach and exhibit programmes, managers, native leaders and indigenous users publication of elders’ narratives, historical photo anxious to test opportunities in their local areas. graphs, catalogues and classical ethnographies this set of regional case studies, again, looks like a addressed primarily to local audiences (e.g. replica of the research once undertaken in the alexeev 1993; etylen 1996; krupnik & narins 1930s under the all-union programme of the kaya 1998; pika 1998). modern research by arctic pastureland inventory and redistribution international teams of tarandus and arctic pasture (zemel ’no-pastbishchnoe ustroistvo). the reports specialists offers an excellent path to document were duly put out as local publications and in a traditional techniques, skills, and practices that are serial named the soviet reindeer industry (sostill in use by native herders across siberia. if vetskoe olenevodstvo, 1932-37). today a similar matched with energetic outreach and dissemina series may be endorsed or even co-sponsored by tion, it could make a critical breakthrough in the recently established russian reindeer-herders public acknowledgement of the value of the union (soyuz olenevodov rossii), obviously a “siberian reindeer civilization” in the same primary potential user of such information. way recent caribou studies in north america have third, the present situation is highly different advanced the standing of native american users’ from the previously documented reindeer crashes traditional ecological knowledge. the thriving in siberia in that the decline in domestic stock is though clearly endangered legacy of native matched (or is followed) by a dramatic increase in pastoralist culture and nomadic lifeways in siberia stocks of wild and feral reindeer (e.g. cherhas to be captured, promoted and re-conveyed to nyavskii & kretchmar 1998). this opens a whole northern residents to ensure its continuity and new spectrum of issues, such as competition and survival in the russian arctic. interaction between domestic and wild reindeer in the same (or similar) eco-niches. feral and wild reindeer stocks also offer new hazards as well as new subsistence resources for herders and native references communities in general. for decades, these issues were of low priority for scientists and users alike almost everywhere in the russian arctic, except for the taimyr peninsula, northern sakha (yaku tia), wrangel island and a few other places. today, the interaction between feral and domestic rein deer may well be listed as one of the most urgent issues for both natural and social scientists engaged in siberian research. here, north amer ican scholars could make invaluable contributions based on their experience in addressing the issues of co-management of caribou (wild reindeer) populations, control over high-tech poaching by outsiders, and prospects for tourist caribou hunting in siberia. last but not least is the issue of cultural abryutina, l. 1. 1997: narody severa. problemy, analiz prichin i perspektivy ikh preodoleniia. (peoples of the [russian] north. problems, their causes and prospects for solution.) paper presented at the constructing cultures then and now conference. new york, 13-17 november 1997. abryutina, l. i. 1998: kratkaia kharakteristika mediko sotsial’nykh problem korennykh malochislennykh narodov chukotki. (medical and social problems of the native minorities of chukotka: a brief summary.) paper presented at the 3rd congress of the international association of arctic social scientists. copenhagen, 21-23 may 1998. alexeev, a. a. 1993: zclbytvi mir predkov. ocherki trcrditsion nogo mirovozzreniia evenov severu-zapadnogo verkhoiania. (the forgotten universe of our ancestors. traditional beliefs of the even of north-warern verkhoyansk regiun.) yakutsk: sitim. alexeev, a. a. 1999: the system of reindeer husbandry under modern conditions in the republic of sakhdyakutia and the ways out of crisis. paper presented at the international 54 reindeer pastoralism in modem siberia workshop, the human role in reindeedcaribou systems. rovaniemi, 10-14 february 1999. anderson, d. g. 1995: the aboriginal people of the lower yenisey valley: an ethnographic overview of recent political developments in north central siberia. pol. geogr. 19(3), 184-2 18. anderson, d. g. 1996: national identity and belonging in arctic siberia: an ethnography. evenkis and dolgans of khantai skoe ozero in the taimyr autonomous district. ph.d. thesis, university of cambridge. bj@rklund, i. 1995: a journey to the bolshezemelskaja tundra. in i. bj@rklnnd et a]. (eds.): the barents region. pp. 71-80. troms0: tromsg museum. charnolusskii, v. v. 1 9 3 0 materialy po bytu loparei. opyt opredeleniia kochevogo sostoianiia loparei vostochnoi chasti kol’skogo poluostrova. (data on the daily life of the lapps: an attempt to estimate the state ofnomadism among the lapps of the eastern kola peninsula.) leningrad: russkoe geo graficheskoe ohshchestvo (russian geographical soc.). chernyavskii, f. b. & kretchmar, m. a. 1998: wild reindeer rangifer tarandus (l.) in chukotka. rangifer 1 8 ( 3 4 ) , 127 132. chichlo, b. 198 i : la collectivisation en sibkrie: un problbme de nationalit&. (collectivization in siberia: the ethnic problem.) in: l’expe‘rience soviitique et le probl2me nationale dans le monde ( 1 9 2 e l 9 3 9 ) . vol. i . (the soviet experience and world nationality problems [1920-1939]. vol. 1.) pp. 219-307. paris: langues. csonka, y. 1998: la tchoukotka. une illustration de la question autochtone en russie. (chukotka. an illustration of the indigenous issue in russia.) rech. amcrindiennes au qukbec 28(1), 2 3 4 1 . druri, i. v. 1936: pastbishchnoe khoziaistvo i vypas olenei u chukoch anadyrskogo raiona. (pasture economy and reindeer herding among the chukchi of the anadyr district.) trudy arkticheskogo instituta 62, 105-124. moscow. etylen, v. m. 1996: chukchi. (the chukchi.) in i. krupnik (ed.) and v. chaussonnet (compiler): perekrestki kontinentov. kul’tury korennykh narodov dal’nego vostoka i aliaski. (crossroads of continents. cultures of indigenous peoples of the [russian] far east and alaska.) pp. 20-2 1. washington and moscow: smithsonian institution and institute of cultural heritage of russia. etylen, v. m. 1999: what kind of a crisis can reindeer herding in cbukotka endure? paper presented at the international workshop, the human role in reindeedcaribou systems. rovaniemi, 10-14 february 1999. ettyryntina, m. & kotyagin, a. 1996: to live or to die? in a. pika, j. dahl & i. larsen (eds.): anxious north: indigenous peoples in soviet and post-soviet russia. iwgia document 82, 227-231. copenhagen. fondahl, g. 1998: gaining ground? evenkis, land, and rejorm in southeastern siberia. needham heights, ma: allyn & bacon. forsyth, j. 1989: the indigenous peoples of siberia in the twentieth century. i n a. wood & r. a. french (eds.): the development of siberia. pp. 12-95. new york: st. martin’s press. forsyth, j . 1992: a histdry of the peoples of siberia: russia’s north asian colony, 1581-1990. cambridge: cambridge university press. golovnev, a. v. 1995: govoriashchie kul’tury. traditsii samodiitsev i ugrov. (talking cultures. traditions of the samoyedic and ugrian peoples.) ekaterinburg: russian academy of sciences. golovnev, a. v. & osherenko, g. 1999: siberian survival: the nenets and their story. london: comell university press. gray, p. a. 1997: snezhnoe, where east and west collide. transitions: changes in post-communist societies 4(6j, 96 100. gray, p. a. 1998: pursuing a native movement in a russian spacer the predicament of indigenous peoples in post-soviet chukotka. ph.d. thesis, university of wisconsin. kerttula, a. m. 1996: antler on the sea: chukchi, yupik, and newcomers in the soviet north. ph.d. thesis, university of michigan. khrushchev, s . a. & klokov, k. b. 1998: nenetskoe olenevodstvo: podkhody k razrabotke kontseptsii ustoichi vogo razvitiia. (the nenets reindeer industry: a strategy f o r sustainable development.) etnogeograjicheskie i etnoekolo gicheskie issledovaniia (ethnogr. ethnol. stud.) 7. st. petersburg. kladkin, v. m. 1999: sovremennye problemy olenevodches kogo khoziaistva. (modem problems in reindeer industry.) nauka-olenevodstvu (information bull.) i , 9-13. yakutsk. klokov, k. b. 1996: kochevoe olenevodcheskoe naselenie: otsenku vozmozhnostei etnosotsial ’noi adaptatsii i razvitiia. (the nomadic reindeer herders: prospects f o r ethno-social adaptation and development.) etnogeograficheskie isstedo vaniia (ethnogeogr. stud.) i. st. petersburg. klokov, k. b. 1998: traditsionnoe prirodopol ’zovanie kor ennykh malochislennykh narodov severa: geograficheskie i sotsial’no-ekologicheskie aspekty problem);). (traditional land use system of the indigenous northern minority peoples: geographical and socio-ecological aspects.) doctorat diss. summary (avtoreferat), institute of geography, russian academy of sciences. krupuik, i. 1989: arkticheskaia etnoekologiia. modeli traditi sionnogo prirodopol ’zovaniia morskikh okhotnikov i olene vodov severnoi evrazii. (arctic ethno-ecology. models of traditional subsistence of marine hunters and reindeer herders of northern eurasia.) moscow: nauka publ. krupnik i. 1993: arctic adaptations. whalers and reindeer herders of northern eurasia. london: university press of new england. krupnik, i. & narinskaya, n. e. (eds.) 1998: zhivoi yamaw living yamal. exhibit catalog. moscow: sovetskii sport. kwon, h. 1993: maps and actions: nomadic and sedentary space in a siberian reindeer farm. phd thesis, university of cambridge. minc, l. d. 1986: scarcity and survival: the role of oral tradition in mediating subsistence crises. j . anthropol. archaeol. 5, 39-1 13. pika, t. i. (ed.) 1998: zemlia yarnal. albom yamal’skikh ekspeditsii v.p. evladovdthe land of yumal. catalogue of v. evladov’s yamal expedition. moscow: sovetskii sport. pokhoziaistvennaia perepis ’ pripoliarnogo severa sssr 1926 1927 g. territorial’nye i gruppovye itogi perepisi. (economic census of the polar north of the ussr, 1926-1927. area and group data.) 1929. moscow: statizdat. sergeev, m. a. 1955: nekapitalisticheskii put’ razvitiia malykh narodov severa. (non-capitalist path of development of the small-numbered peoples of the north.) trudy instituta etnografii a n sssr (proc. inst. ethnogr. ussr acad. sci.) 27. moscow. sosunov, p. i . 1925: tobol’skii sever. (northern areas of the tobotsk province. j severnaia aziia 3-4. leningrad. krupnik 2000: p o l a r r e s e a r c h 19(1), 49-56 5 5 stansev, b. 1997: doroga v nikuda. korennym narodam chukotki ne vyzhit' bez gosudartsvennoi podderzhki. (the route to nowhere. native people of chukotka cannot survive without state support.) ltogi 3. 56-61, moscow. sukhaya. s . 1999: sindrom poliarnogo ndpriazheniia. (polar stress syndrome.) trud 28(232531, 1-2. moscow. takakura. h. 1998: reorganization of the reindeer industry under de-sovietization; a transformation of a soviet village community in northern yakutia, siberia. (in japanese, with english summary.) jpn. j. ethnol. 63(1), 1 9 4 3 . tuisku, t. 1998: a traditional livelihood in the 1990s a case study of nenets reindeer herding in north-west russia. paper presented at the 3rd congress of the international association of arctic social scientists. copenhagen, 21-23 may 1998. vakhtin, n. b. 1994: native peoples of the russian far north. in: polar peoples. self-deiermination and development. pp. 29-80. london: minority rights group. (originally publ. 1992.) vakhtin. n. & krupnik, i. 1999: power, politics, and heritage: undercurrent transformation in the post-soviet arctic the case of chukotka. in f. sejersen (ed.): changes in the circumpolar north. culture. ethics. and self-determination. topics in arctic social sciences 3, 27-42. copenhagen: iassa. vasil'ev, v. i. 1970: nentsy i entsy taimyrskogo natsio nal'nogo okruga. ocherk khoziaistva, byta i etnicheskikh protsessov, protekayushchikh na eniseiskom severe. (the nenets and enets people of the taimyr national area. economy, daily life, and ethnic processes of the northern yenisey river region.) in b. 0. dolgikh & i . s . gurvich (eds.): preobrazovaniia v khoziaistve i kul'trtre i etnicheskie protsessy 11 narodov severa. (econoniic and cultural transformation, and ethnic processes among the peoples oj the north.) pp. 106-163. moscow: nauka publ. vedoniost' dviiheniia pugolov'ia pu sovkhozani okruga. (rein deer stock change by state farms. general statistical sheet, 3980-1995) 1996. anadyr: area office of agriculture. vitebsky. p. 1992: landscape and self-determination among the eveny. the political environment of siberian reindeer herders today. i n e. croll l d. parkin (eds.). bush base: forest farm. culture, environment, and development. pp. 223 246. london: routledge. williams, d. 1997: creating a hot property in siberia is every bit as hard as it sounds. the washington post oct. 3. a29, ,434. yoshida, a. 1991: kid 'turn pitania gydartskikh nenrsev: interpretatsiia i sotsial 'naia adaptatsiia. (culture of' food consumption of the gydan nenets: interpretation and social ndaptation). moscow: institute of ethnology. tadorin, v.1 . 1999: the beginning of the end of vet another branch of human civilization. paper presented at the international workshop, the human role in reindeer/ caribou systems. rovaniemi, 1 6 1 4 febmary 1999. ziker, j. p. 1998: kinship and exchange among the dolgan and nganasan of northern siberia. res. econ. anthropol. 19, 191 238. 56 r e i n d e e r pastoralism in modem siberia gonad maturation as an indication of seasonal cycles for several species of small copepods in the barents sea m. fredrika norrbin norrbin. m. f. 1991: gonad maturation as an indimtion of seasonal cycles for several species of small copepods in the barents sea. pp. 421-432 in sakshaug, e., hopkins, c. c. e. & britsland, n. a . (cds.): proceedings of the pro mare symposium on polar marine ecology. trondhcim, 12-16 may 1990. polar reserch i o ( 2 ) . i n a remote oceanic area likc the barents sea. it is often difficult to follow the seasonal developmcnt of copcpod populations in detail. information on the gonad maturation stage of older juveniles and adults of a species will reveal the immediate state of reproduction and the expected development of juveniles into reproductively active adults. winter “resting stages” in juveniles can also be rccognised. zooplankton were caught during pro mare cruises in early march. may. july/august, mid-scptember and mid-october. abundance and composition of developmental stages of small copepods were determined for several stations from each cruise. samples consisting of stages civ to cvi of pseudocalanus acupes (giesbrecht 1881). p. minufus (kroyer), microcnlanus pusillus (sars). and m . pygmaeus sars were stained with carmine and analysed with respect to gonad maturation stage. length. width, and area of the prosome and the area of the gonad and the oil sac. image analyses were performed from photographs or drawings of copepods using a digitising pad. with additional information on abundance and stage composition, and by comparing the present data set with information on pseudocalanus spp. from balsfjordcn, northern norway, seasonal cycles for the species could be inferred. fredriku norrbin. depurfment of aquatic biology. the norwegiun college of fishery science. p . 0. box 308.3 guleng. n-9001 tromsm, norway (reuised february 1991). introduction in arctic and subarctic areas, where the yearly input from primary production to higher trophic levels is typically limited in time, the dominant species of large, herbivorous copepods are known to be active during only part of the year (hopkins et al. 1984; tande et al. 1985). they produce one or less than one generation per year and spend most of the time either building up energy stores or in a resting state, slowly consuming these reserves. the many smaller species of copepods have been described in several studies of high latitude zooplankton (e.g. ussing 1938; digby 1954; fon taine 1955; grainger 1959; mclaren 1969). although numerically dominating in nearshore arctic areas (horner & murphy 1985), the small species have lately been found to be of little importance in offshore ecosystems (e.g. cooney & coyle 1982; vidal & smith 1986). however, many of the recent studies have been conducted primarily during the spring and summer seasons, while high abundances of small copepods have been recorded mainly during the second half of the year (minoda 1967; hassel 1986; the present study). in many cases the nets used have been too coarse to catch young stages of microcalanus in particular. this suggests that smaller species may still play an important role in arctic food webs during autumn and winter. gonad maturation has been used to describe life cycles for large, herbivorous copepods and some smaller species in balsfjorden, northern norway (tande & hopkins 1981; tande & gron vik 1983; norrbin 1987) and in the barents sea (tande et al. 1985). experimental work with a small copepod from temperate areas shows that the gonads of juveniles grow larger under good feeding conditions (razouls et al. 1987). this is reflected in seasonal cycles in gonad size and maturation of pseudocalanus in balsfjorden (norrbin 1987). in balsfjorden, the drop in gonad 422 m . fredrika norrbin size of juvenile pseudocalanus in late summer anticipates the beginning of the overwintering resting period long before signs of this are visible in other factors (norrbin 1987; unpubl. data). during the latter part of the pro mare programme, some of the cruises took place during autumn and winter, enabling the study of biologial material from the “unproductive” season. the aim of this project within pro mare has been to evaluate the importance of the smaller species of calanoid copepods in the barents sea ecosystem, with an emphasis on their significance during the time when larger calanoids are inactive. in this paper information on stage composition and gonad maturation is used to infer seasonal life cycles for four copepod species; pseudocalanus acuspes, p . minutus, microcalanus pusillus, and m . pygrnaeus. materials and methods plankton was sampled during the pro mare cruises of 1987 and 1988; cruise 11 in march 1987, cruise 13 in october 1987, cruise 14 in may 1988, and cruise 16 in september 1988 (fig. 1). additional samples derive from cruise 2 in july august 1984 (fig. 1). the region covered by sampling typically consisted of latitudinal tran sects into the ice edge followed by a number of stations in ice-covered waters. sampling equipment usually consisted of 90 pm wp-2-nets. on cruise 12, a 200 pm wp-2 net was used and on cruise 10. a 90 pm juday net (for a description of the nets, see e.g. unesco 1968). zooplankton was concentrated and preserved in a solution of 4% formaldehyde and 5% propylene glycol immediately upon sampling. this was exchanged for a weaker preservative upon return to the laboratory. stage and sex composition of small copepod species were estimated from subsamples. a mini mum of 1000 individuals were counted from each station. gonad maturation of males and females of copepodite stages iv to v was analysed for the species pseudocalanus a c w p e s (giesbrecht, 1881; see frost 1989), p . minutus (kroyer), micro calanus pusillus (sars), and m . pygrnaeus sars (fig. 2). (the genus microcafanus is currently subject to some taxonomic confusion. the species in this study have been determined as far as possible l i fig. 1 . the western barents sea. stations from pro mare cruises. starting and end stations are indicated. the lines connecting the stations signify different cruises; small dots = cruise 10; larger dots = cruise 13: unbroken line = cruise 14; lines and dots = cruise 16. in addition. stations from cruise 2 relevant for this study are denoted by triangles. according to sars (1903), brodskii (1950) and vidal (1971). occasional specimens of micro calanus s p . b were found in the samples (vidal 197 1)). there was a great variation in the abundance of different species and developmental stages in samples from different stations and seasons. the aim was to analyse at least 20 copepods of any given stage and sex from each station, but this was often not possible. copepods were stained in ethanolic borax car mine for several days, then rinsed in distilled water, dehydrated in ethanol and finally trans ferred to cedar wood oil (norrbin 1987). groups of stained copepods were arranged in a lateral position in cedar wood oil on a glass slide (figs. 2 and 3). they were then photographed through a wild heerbrugg dissecting microscope. the resulting colour slides were projected down on a calccomp 2500 digitising pad. several rneasure ments were taken (see below) and fed directly into a computer file using a specially adapted seasonal cycles of small copepods in the barents sea 423 taneously, notes were made of gonad maturation stage (after corkett & mclaren 1978; tande & hopkins 1981; norrbin 1987). analysis of the data was performed using mic rosoft excel spreadsheets and statgraphics stat istical graphics system, version 3.0. a c d 0 1000 pm i -i fig. 2. species in the present study. appearance of stained copepods. the figure shows prosome and urosome in lateral view. a. pseudocalanus acuspes cv female in advanced state of maturation. b . p . minufus cv female in gonad resting state. c . microcalanus pusillus cv male with medium-sized gonad. d. m. pygmaeus cv male in gonad resting state. basic programme which calculated distances and areas. a small number of the copepods were drawn on paper using a camera lucida instead of photography. these were digitised in the same way as above. the measurements taken were prosome length and greatest width, area of prosome, area of gonad, and area of oil sac (fig. 3). simul prosome area gonad area / gut oil sac area length fig. 3. measurements taken on copepods using digitising table. results species composition all four species in this study co-occurred on sta tions in the western barents sea (table 1). there was a tendency for pseudocalanus to be dominant in shallow areas and for microcalanus to be more dominant in water of more than 200m depth (table 1). abundances were generally higher in the south ern part of the investigated area and copepod numbers increased during the year, reaching a maximum in september and october (table 1). stage distribution some features of the stage distributions of all copepod species in the present study are especially noteworthy; presence of adult females indicates ongoing or recently ceased reproduction, and presence of adult males indicates that mating and reproduction have recently begun. a large num ber of early copepodites (ci) is a sign of recent reproductive activity and ongoing development of the population. mclaren (1974) and corkett & mclaren (1978) give a development time from egg to ci of approximately 45 days at 0°c for pseudocalanus). absence of the youngest stages and a predominance of ciii to cv imply an accumulation of overwintering stages. because stage distribution varied between regions, the figures representing this distribution are divided into five areas (figs. 4 to 7): atlantic water north and south of approximately 76“n, polar water north and south of approximately 7yn, and shallow areas at 75 t o 77”n (on spits bergenbanken or hopenbanken), usually with mixed water masses. representative stations from each sampled region are shown for march, may, september, and october (figs. 4 to 7; table 1). northerly atlantic water stations and southerly polar water stations overlap due to the fluc tuation of the position of the polar front. most stations were localised in the marginal ice zone, 424 m . fredrika norrbin table 1. zooplankton sampling data for the pro mare cruises and abundance of small copcpods. "region" refers to regional divisions used in figs. 4 to 7. p.a. = pseudocalanus acuspes. p . m . = p. mbiurus. m.pu. = microcalarius pusillus. m.py. = m . pygmaeus. total = total small copepods including cyclopoida and harpacticoida. a plus sign signifies an abundance of less than one individual per cubic meter. positron depth abundance of small copepods (individuals m-:) date station region lat long ( m i ~ . a . cruise 2 , 1984 21 jul 11 01 aug 111 01 aug 118 01 aug 137 m a u g 160 cruise 10. 1987 01 mar 2 02 mar 6 06 mar 13 cruise 13, i987 15 oci 1 i6 oct 5 16 oct 7 20oct 12 22 oct 15 24 oct 17 cruise 14, 1988 21 may 3 21 may 5 21 may 6 22 may 7 23 may 9 24 may 10 27 may 13 3omay 16 cruise 16, 1988 g9sep 1 10 sep 3 10 sep 4 1 1 sep 6 1 1 sep 8 i3 sep 12 14 sep 13 17sep 16 c d c e d b b c e e d d d b c c c d b a a 78"4x'n 80"12'n 80'52" ri"i8'n 79"40'n 75"16'n 75"49'n 76"l i'n 73"10'n 76'00" 77"w'n 78"ol ' n 77"40'n 77"15'n 74"w'n 75"00'n 76"03'n 76"22'n 76"16'n 76%" 76"10'n 75"2y'n 76"w'n 76"34'n 77"w n 78"00'n 79"m'n 80"33'n 80"12'n 7953" 28"iy' e 24"16'e 23"oo'e 22"20'e 26"26'e 23"3 1 ' e 30"m'e 22"5 1 ' e 27"58'e 32"io'e 32"00'e 31"41'e 3020'e 29"oo'e 31"13'e 3173'e 3 1 w ' e 31"03'e 29y7'e 27"li'e 2355'e 23"31'e 28"oo' e 2 8 2 8 ' e 29"26' e 3 1 w ' e 31"56'e 30"28'e 29"42'e 28"05 ' e 30 195 55 220 150 114 325 48 320 320 210 204 208 187 279 358 335 304 24 1 91 42 85 167 72 232 233 80 207 215 311 0 23.121 98 6.369 38.270 5.931 25.134 0 15.971 12.015 1.492 2.738 300 1.307 1 .ox5 505 557 1.258 4.832 133 10.369 iw,210 53,897 2.871 16.332 27.269 26.742 54.055 88. i 30 p . m . ~ 4go 1.861 11,757 18.693 2.246 4.397 982 + 10.394 11.348 1,014 16.81 1 573 1.502 980 1.883 842 658 802 392 333 8.791 23.739 9.503 269.8 10 29,705 13.639 8.413 11.605 . . m.pu. m.py. total 0 0 9.013 392 0 + 2,492 + 8.630 + 34.200 614 82 + 27.840 0 246.493 9.328 60,744 5.340 457 477 10.443 225 1.592 + 82.028 601 8.479 + 12,673 1.199 11.765 787 5 , 5 0 9 692 350 + 0 0 2,332 loo 7.664 676 + + 13.640 638 1,816 306 0 157 9.471 2.567 9.915 3.906 11,146 2.266 833 54.766 28.412 46.663 109,134 243.645 29,882 127.069 1,470,505 580.742 9.728 326.286 28. i46 232.864 213,115 214.836 172.019 125.871 27,003 8.687 9.260 664.957 456,158 2.000.267 1.631,141 177,806 148.026 182.986 193.279 but the southernmost stations of each cruise were usually set up in open water: stations one to seven of cruise 13. one t o six of cruise 14. and stations one to six of cruise 16. during cruise 2 all stations except no. 111 were localised in open water. pseudocalanus acuspes in march the population of p. acuspes was still dominated by overwintering copepodites (ciii to cv; fig. 4). in may the population was in a developing phase at most stations, as evidenced by the presence of ci (20 to 40%) and older juvenile stages (fig. 4 ) . the shallow water sta tions (fig. 4c) where adults dominated were an exception. in these areas there were high densities of cirripedia nauplii which may have preyed on young copepodite stages. the southernmost, open water station (fig. 4e) had the highest number of young copepodites. in july/august there seemed to be developing populations of p. acuspes at stations to the west of nordaust landet. north of svalbard the populations were either i n a developing phase or dominated by older juveniles. in september, there was a clear predominance of early copepodites in most areas (fig. 4a, c and d). very few older copepodites and adults were present, except for a lingering population of adult females at the southerly polar water stations (north of 77'"; fig. 4b). the stage 111 copepodites may have represented the build seasonal cycles of small copepods in the barents sea 425 r p . acuspes f 50 0 5 0 5 0 0 50 50 0 5 0 5 0 0 50% march may september october f;g. 4. seasonal stage distributions for pseudocalanus acuspes. the presentation is divided into sevcral gcographical areas (from north to south): a . 79-81"n. polar water. b. 76-78"n. polar water. c. 75-77"n. shallow (bank) areas with polar or mixed water. d. 76-77"n. atlantic water. e. 7s75"n. atlantic water. distributions arc givcn as pcrccnrages of all copepodites. females are placed to the right of the vertical bar and males to the left (sex was determined for copcpoditc stages iv to vi). each distribution represents one to three similar stations. see table 1, "region" column, for information on stations used in the construction of this figure. where a distribution is based on less than 100 copepodites, the number is given in the figure. p . minutus 11 ii a i . i1 i t i i 7 l * n=39 n=32 p 1 7 n = 5 9 1 1 i a n=26 50 0 50 september 50 0 50% october 50 0 50 may 50 0 50 march fig. 5 . seasonal stage distributions for pseudocalanus minutus. see fig. 4 for clarification 426 m . fredrika norrbin m . pusillus 50 0 march l n=2 1 f n=70 i ?€.!.i n = 1 4 r n=34 50 0 50 may 50 0 50 september fig. 6. seasonal stage distributions for microcolonus purillus. see fig. 4 for clarification up of the overwintering population. no adult males were present. i n october early copepodites were still present. but the adults had disappeared (fig. 4 ) . pseudocalanus minutiis i n march adult females of p. minutus were present at several stations (fig. 5). copepodite stages i1 and 111 at these stations may have repre sented reproduction earlier in the winter or part of the overwintering population. i n may there was a dominance of adults and older juveniles at all stations (fig. 5). as in p . acuspes, the highest concentrations of younger copepodites were found at the most southerly station (fig. 5e). in july/august the situation was similar to that of p. acuspes. in september the accumulation of overwintering stages had proceeded further than for p. acuspes. with 50 to 70% of the population consisting of copepodite stages 111 to v . as in p. ncuspes, there were no adult males, but adult fema!zs were still present at northerly stations (fig. sa). in october the dominance of over wintering stages was almost total (fig. 5 ) . there were, however. females present at the north f t n=25 i 50 10 5 0 % october ernmost stations (fig. 5b). where grazing seemed to occur. microcaianus pusillus i n march all stages of m . pusillus except adult males were present, suggesting that reproduction had taken place earlier in the winter (fig. 6c and d). all developmental stages were found at most stations in may (fig. 6), but at shallow water stations adults and older juveniles dominated (fig. 6c). in july/august populations seemed to consist largely of adult females. but the younger copepodites are likely to have slipped through the 200pm net because ci to ciii of this species measure n o more than 200 to 340 pm in prosome length. in september the younger copepodite stages comprised 10 to 30% of the populations (fig. 6). adult females were abundant especially in areas influenced by polar water (fig. 6a, b and c) and adult males were present on the northernmost stations (fig. 6a). all devel opmental stages were still present in october, but older juveniles and adults predominated (fig. 6). adult males were present at most stations. seasonal cycles of small copepods in the barents sea 327 ii i a in m . pygmaeus 50 0 5 0 5 0 0 5 0 5 0 0 50% march may september october fig. 7. seasonal stage distributions for microcalanus pygmaes. scc fig. 4 for clarification. 401 x o 10 20 30 40 m 80 i m m 4 0 60[ f # \ 2010 0 0 i 10 20 30 40 f " i i i i i 10 20 30 40 r d t a 0 a a t a j a o*& a a oil sac index i i i i i 10 20 30 40 50 fig. 8. seasonal variations in gonad size and oil content. station averages for civ females. civ males. cv females and cv males. oil sac index = oil sac area as percentage of prosome area. g/g,., = gonad area as percentage of maximum observed gonad area in the specific copepodite stage and sex. open squares = march. solid squares = may, diamonds = july/august. solid triangles = september. and open triangles = october. arrows show the seasonal cycle of resource allocation to either gonads or oil. a. pseudocalanus acuspes. b. p. minutus. c . microcalanus pusillus. d. m . pygrnaeur. 428 m. fredrika norrbin microcalanus pygmaeus in may the stage distribution of m . pygniapirs was similar to that of m . piisillus (fig. 7). in september, stage distribution at most stations resembled that of p. minutus. with a dominance of older copepodites and adult females (fig. 7a and d). some adult males were present, indi cating that the populations were not completely "at rest". in october, older juveniles made up from 60 to 100% of the populations, but adult males were still present at polar water stations (fig. 7b). very few specimens were found in the march and july/august samples. seasonal oariation in gonad size and oil content seasonal cycles of energy allocation were evident i n stages civ to cv of all four species (fig. 8). i n may, when gonad sizes were at their maximum. the copepods contained little oil. oil content increased and gonad size decreased as the season progressed. maximum oil sac sizes were attained in september for all species. minimum sizes in gonads were found from september to october for pseudocalanus acuspes and micro calanus pygmaeus, from august to september for p. minutus, and in october or march for m . pusillus. in p . acuspes civ and cv gonad sizes reached a maximum in may (fig. 8a). at the same time, oil content reached a minimum i n this species. in september, copepodites from the northernmost stations tended to have smaller gonads than those from stations further south. gonads of p. minutus copepodites reached their greatest size in may (fig. 8b) but were large in some localities both i n early august and in mid-september (late summer situations). in early march, gonads increased in size while oil content decreased in all species except m . pusillus (fig. 8 a and b ) . in p. acuspes civ, but not in cv, gonads were larger in march than in the period september/october. indicating the start of spring maturation in the overwintering generation. in p. minutus stage v copepodites also displayed this sign of early maturation i n march. oil stores were nearly depleted i n this species in march (fig. 8b). the seasonal cycles in both gonad size and oil content were much less-pronounced in the microcalanus species (fig 8c and d). cope podites from may, september and october exhibited some large gonads but also smaller and fig. 9. life cycle and gonad development of a small calanoid c o p e p d . inner pathway represents direct development during productive season. resting stages usually consist of civ-cv (pseudoco~anuc acuspes also ciii) and are formed before winter. in winter-early spring these stages enter the cycle of normally moulting and maturing copepodites. less mature ones. consistently small. only in march were gonads discussion seasonal cycles in maturation the results presented here indicate trends in gonad maturation and in the population dev elopment of small copepods. more frequent sam pling is needed i n order to describe seasonal cycles in detail. it is obvious from earlier studies that small, undeveloped gonads can be used to identify resting copepodites, and that gonads in cope podites during the productive season always appear in a wide size range with a predominance of larger size groups (fig. 9; norrbin 1987; unpubl. data). the size increase in gonads of female copepodites is due to the prolongation of the gonad into forward diverticulae and to maturation and migration of oocytes. razouls et al. (1987) showed that gonads of cv females of temora stylifera grew more i n size under good food conditions. this should lead to efficient util isation of abundant food regimes, allowing for early maturation and reproduction in the adult stage. in may and august several specimens of pseudocalanus cv females had ova in their ovi ducts. in male cv t h e reproductive system could also be well differentiated, with a visible sperm sac and spermatheca. i t is likely that the seasonal cycles of the pseu docalanus species in the souhern parts of the seasonal cycles of small copepods in the barents sea 429 o n d j f m a m j j a s o l ' " ' " ' ' l i i fig. f0. seasonal cycle in gonad size for cv females from balsfjorden, northern norway 1985-86. gonad size was measured as gonad length. a . pseudocalanus acuspes. b . p . minutus. data modified from norrbin (unpubl. data). barents sea (72 to 76'n) are similar to those in balsfjorden (69'30"). in the northern areas, which are ice-covered most of the year, there is likely to be a shorter productive period, which results in fewer generations per year. the seasonal variation in gonad length for pseudo calanus acuspes and p . minutus cv females in balsfjorden (fig. lo), together with monthly analyses of stage composition, indicates three generations of p . acuspes and two generations of p . minutus per year in this area (norrbin 1987). overwintering cv females of p. acuspes mature between march and april; the first new gen eration of the year matures in may and there is a second generation which matures in july before the build-up of the new overwintering population begins in august (fig. 10a; norrbin 1987). the overwintering generation of p. minutus matures in the february-march period and cv cope podites disappear until may (norrbin unpubl. ; fig. 10b). the first generation matures in may and from june onwards the overwintering gen eration is formed, with gonads slowly developing during autumn and winter (fig. 10b). this pattern is closer t o that of the larger copepod calanus finmarchicus in this area (tande & hopkins 1981). similar presentations of gonad size are given for cv females of the four species in the present study (fig. 11). since gonad length was not measured here, and area is proportional to length squared, the square root of the gonad area measurement has been used in fig. 11. a constant relating area and length is lacking, giving lower values for the barents sea copepods (fig. 11). the barents sea data for the pseudocalanus species imply similar cycles. for p . acuspes the stage composition and state of maturation of over wintering juveniles were almost identical in the barents sea and balsfjorden in early march (figs. 4, 10a and 11a; norrbin 1987). in may there is an obvious maturation of the first generation (fig. 11a). it is likely that two to three generations of 0 ' 4 [ a 0.2 0'41 -€ e l (ii m t 0 0, o'21 0.1 \ 't 0.2 0.1 0 0 till,, o n d j f m a m j j a s fig. if. seasonal cycle i n gonad size for cv females from the barents sea (present study). gonad sizes were measured as gonad areas. the square root of this measurement was taken to approximate a length measurement; due to lack of a scaling constant these values are smaller than in fig. ioa. a. pseu docalanw acuspes. b . p . minutus. c. microcalanus pwillus. d. m. pygmaeus. 430 m . fredrika norrhiri this species occur per year also in the southern parts of the barents sea. further north there a r e probably fewer generations. maturation of p. r n i n i r f u . ~ may occur somewhat later in winter in the barents sea. in the northern parts of the barents sea. the whole cycle is likely to be delayed. leaving room for only o n e generation per year. i n other arctic localities. p . rnitzitiirs has been found to be mainly annual (ussing 1938: digby 1954: fontaine 1955) or with a life cycle taking from o n e and a half t o two years t o com plete (digby 1954; grainger 19%). however. since a revision of the genus p s r ~ k m l a r i i r s has taken place only recently (frost 1989). several species may have been involved in these studies. ps~irdoc~mlcitiiis females may be reproductively active for up to two months (corkett & mclaren 1978). this may account for the presence of adult p. m m t m . s females in september and october. late breeders were also found by fontaine (1955) i n u n g a v a bay. offspring produced this late may have difficulty in surviving under the poor food condition\ during winter. population densities in march art. only 5 to i o v of those i n september and october (table i ) . i t is clear that mic.roculurius pir.sil/ir.s cope podites h a w a higher degree of maturity later i n the season than pseirrlocczlrrnlr.( (figs. 10 and 11). the extent of nlaturity of ,v, pfgr,luell,y cope pndjres seen,s to var! l i t t l e c j r l r i n g t h e y e a r ( f , ~ , a higher degree in this species. as it does in accirfio ~ o r ~ g i r u r ~ r i s ( n o r r b i n 1987) and in the larger cope pods (tande et al. 1085). paoouctive season period m . pusillus m . pygmaeus p. acuspes t p. minutus increasing size: ~ i g . 12. p o ~ s ~ ~ i c beasonat cycich i n the productitin perl,,d f o r four~peciesofcopepods i n the western barents sea. the shaded area represents the period of reproduction and developing juveniles in the foulhern and central parts of the investigated area. the spccics arc arranged i n circles related to prosome the lnnermc>st clrcles. the diameterofeach circle is proportional the prosornc length of the specie\ i t reprcwnts. the length of the productive season is roughly inversely proportional t o ~ i l c ot the copepod specie\. d ) . perhaps matur'ltion occurs in the to length. w i t h the smalleq specie\ ;ind longrst activity pcrlods in oil siic s i z e i t is bigniticant that the hmallest species in the present study are those which vary the least in fat reserves (fig. 8). small copepods such as micro culuri~t.7 ( c v and adults of the smaller iw. yiczi/liis reach a prosome length of about 0 . 5 m m ) are likelk t o be vulnerahle to starvation due to rela tively large metabolic needs. smaller organisms have higher weight-specific basal metabolic rates (kleiher'\ law). increasing their needs for a con stantl! renewed food supply. this may be the prime reason why small copepods have a longer a c t i v i t y period during the year. o r . to be precise. why some copepods have undergone a n adap tation to a prolonged activity season consisting of a decrease i n size. t h e microcalati~is species are therefore unlikely to abstain from feeding at any part of the year: their likely food source is detritus a n d small organisms found in deeper waters. t h e main distribution of microccrlunus lies in sub surface waters (50 to 1200m. buchanan & sek erak 1982: 200 to 500 m. s a m r o t o et al. 1986: below 1 0 0 m . norrbin unpubl. d a t a ) . fat stores may be an adaptation to short term food varia bility (hikansson 1985) rather than a means t o early maturation i n these species. the largest seasonal variation in oil sac size i s found in pwrdocnlnrws rninutirs. the small copc pod species which most resembles the large, her bivorous copepods (fig. 8b). t h e fat stores seem to be deleted during the winter, probably con tributing both to survival and maturation (figs. seasonal cycles of small copepods in the barents sea 431 8b and 10b). during the productive season, in may, energy appears to be allocated both to matu ration and fat stores (fig. 8b). in p . acuspes, on the other hand, the smallest oil sacs are found in may, not in winter. at this time of abundant food, energy seems to be directed into rapid growth and maturation instead of reserves (fig. 10a). this is consistent with information on the lipid class and fatty acid composition found for this species in balsfjorden (norrbin et al. 1990). in conclusion, the seasonal allocation patterns of these four species reflect other aspects of their ecology. p . acuspes is essentially a coastal species, growing quickly when food is abundant, but accumulating energy for winter. females carry egg-sacs until hatching, implying elements of “k strategy” (sensu macarthur & wilson 1967). p. minutus is even more of a “k-strategist”, an oce anic species resembling the large herbivores, with a shorter developing season and a long resting period. microcalanus spp. are deeper-living species relying on fat storage and detritivory. eggs of microcalanus are released directly into the water column (norrbin unpubl. data). the relationship between copepod size and productive periods has been constructed from the details on stage distribution and gonad maturation in this study and is represented in fig. 12. further investigations into feeding habits, dev elopment times and other aspects of the biology of microcalanus and other little studied species are needed. the tendency to lump species together, which is often done with the smaller species, brings confusion into the interpretation of their life histories and general ecology. the fact that closely related species frequently co occur, for example, is an observation of great ecological importance, touching upon themes such as the niche theory and hypotheses for sym patric speciation. acknowledgements. i wish to thank s. diel-christiansen for inspiration and advice during the early part of the preparation of this manuscript and j . marks for linguistic corrections. thanks are also due to the crews of the norwegian coastguard vessels and r/v lance, to k.s. tandc for access to his 1984 samples, to l. dalsboe for assisting with the dehydration of many stained samples. to u. norrmann for adapting the basic digitising program to my needs, and to l. olsen for drawing part of the figures. i am also grateful to my fellow participants in pro mare for cooperation and good company on the cruiscs. this study is part of the pro mare programme and was funded by the norwegian research council for scicnce and the humanities (navf) and the norwegian ministry of the environment. references brodskii, k. a. 1950: calanoida of the fareastern seas andpolar basin of the ussr. keys to the fauna of the ussr. no 3 5 . israel program for scientific translations (translated from russian t o english, 1967). 440 pp. buchanan, r. a . & sekerak, a . d. 1982: vertical distribution ofzooplankton in eastern lancaster sound and western baffin bay, july-october 1978. arcric 35, 41-55. cooney, r. t . & coyle, k. 0. 1982: trophic implications of cross-shelf copepod distributions in the southeastern bering sea. mar. biol. 70, 187-196. corkett, c. j. & mclaren. 1. a. 1978: the biology of pseu docalanus. adu. mar. biol. 15. 1-231. digby, p. s . 1954: the biology of the marine planktonic cope pods of scoresby sound. east greenland. j. anim. ecol. 23, fontaine. m. 1955: the planktonic copepods (calanoida. cyclopoida. monstrilloida) of ungava bay, with spccial ref erence to the biology of pseudocalanus minutus and calanus finmarchicus. j. fish. res. ed. can. 12. 858-898. frost, b. 1989: a taxonomy of the marine calanoid copepod genus pseudocalanus. can. j. zool. 67, 525-551. grainger. e. h . 1959: the annual oceanographic cycle at igloolik in the canadian arctic. i . the zooplankton and physical and chemical observations. j. fish. res. ed. can. 16. 453-501. hassel. a. 1986: seasonal changes in zooplankton composition in the barents sea. with special reference to calanus spp. (copepoda). j. plankton res. 8. 32s339. hopkins, c. c. e., tande, k. s.. gronvik, s. & sargent. j. r. 1984: ecological investigations of the zooplankton com munity of balsfjorden, northern norway: an analysis of growth and overwintering tactics in relation to niche and environment in metridia longa (lubbock), calanus fin marchicus (gunnerus). thyssanoessa inermis (kroyer) and 7. ruschi (m. sars). 1. exp. mar. biol. ecol. 82, 77-99. horner, r. & murphy. d. 1985: species composition and abundance of zooplankton in the near-shore beaufort sea in winter-spring. arctir 38. 201-209. hikansson, j . l. 1985. thelongandshortterm feeding condition infield-caught calanus pacificus. as determined from the lipid content: relationship with phytoplankton pigments in the cali fornia current. dissertation, univ. of gothenburg. 92 pp. macarthur. r. h . & wilson, e. 0. 1967. the theory of island biogeography. princeton university press, princeton. 203 pp. mclaren, i . a. 1969: population and production ecology of zooplankton in ogac lake, a landlocked fiord on baffin island. j. fish. res. ed. can. 26. 1485-1559. mclaren, i. a . 1974: demographic strategy of vertical migration by a marine copepod. am. nut. 108. 91-1u2. minoda. t . 1967: seasonal distribution of copepoda i n the arctic ocean from june to december. 1964. records of oceanographic works in japan 9 ( 1 ) . 161-168. norrbin, m. f. 1987: overwintering and energetic strategies of marine pelagic copepods in high latitudes. m s c . thesis. university of gothenburg, gothenburg. sweden. 101 pp. norrbin, m. f., olsen. r.-e. & tande. k . s. 1990: seasonal variation in lipid class and fatty acid composition of two small copepods in balsfjorden. northern norway. mar. biol. 105. 205-211. razouls, s . . nival, s. & nival, p. 1987: development of the genital system in the copepodid stages of the calanoid cope pod temora srylifera dana. j . mar. b i d . ass. u . k . 67.653 661. 296338. 432 m. fredrika norrbin sameoto. d.. hermann. a . & longhurst. a . 19x6: relations between the thermoclinc meso and microzooplankton. chlorophyll a and primary production distributions in lancas ter sound. polar. biol. 6. s%61 sars. g . 0. iw3: an account of the crustacea of norway. vol. i v . copepoda. calanoidu. bergen museum. bergen. tande. k. s. & g r ~ n v i k . s. 1983: ecological investigations on the zooplankton community of balsfjorden. northern norway: sex ratio and gonad maturation cycle in the copepod merridia longa (lubbock) 1. exp. mar b i d €col. 71. 4% 54. tande. k . s . . hassel. a . & slagstad. d. 1985: gonad matu ration and possible life cycle strategies in calanus fin marrhirus (gunnerus) and calanusglacialrs (jaschnov) in the northwestern part of the barents sea. pp. 141-155 in gray. j. s. & christensen. m . e (eds.): marine biology of polar regions and the effect of stress oil marine organisms. john wiley & sons. chichcstcr. tande. k. s . & hopkins. c . c . e . 1981: ecological invcs tigations of the zooplankton community of balsfjorden, northern norway: the genital system in calanmfinmarchicus and thc role of gonad dcvclopment in thc overwintering strategy. mar. b i d . 63. 15f164. unesco 1%8: zooplankton sampling. lmprimeries populaircs. genkve. 174 pp. ussing. h. h. 1938: the biology of some important plankton animals in the fjords of east greenland. medd. cr@nland loo. 1-108. vidal. j . 1971: taxonomic guides to arctic zooplankton ( i v ) : k e v to the calanoid copepods of the central arctic ocean. university of southern california tech. rep. no. 5 . 128 pp. vidal. j. & smith. s . l. 1986: biomass. growth. and dev elopment of populations of herbivorous zooplankton in the southeastern bering sea during spring. deep-sen res. 33. 523-556. no job name b o o k r e v i e w por_144 139..140 review of climate change: the science, impacts and solutions, by a. barrie pittock (2009). second edition. collingwood: csiro/london: earthscan. 368 pp. isbn 978-0-64309-484-0. it is almost the resort of rascals to claim at the beginning of a book review that “the subject of this book has never been more topical and its publication could not be more timely”. nonetheless, neither barrie pittock nor i are rascals, and the above statement is true. in fact, as i write this review, the australian senate, which has been held back from its christmas recess to complete its debate on a bill to initiate greenhouse gas emissions reduction, is arguing about the cause and its possible cure. i wish i could have every member of the senate (especially the dissenters in the liberal party) read the 350 pages of barrie’s excellent book. of course, as with all good books, they could simply read chapter 1 “climate change matters” and chapter 12 “accepting the challenge”, but as these rascals are politicians it might also be useful for them to read chapter 10, entitled “the politics of greenhouse”. less frivolously, this book (in this new and updated second edition) will become an important reference for students in environmental or social sciences, policy makers, and people who are genuinely concerned about the future of our environment. it covers ground that has been well trodden by the intergovernmental panel on climate change in all four of its assessments, by al gore’s film an inconvenient truth and, just this year, by fanny armstrong’s movie the age of stupid. topics include “learning from the past”, “projecting the future”, “uncertainty is inevitable but risk is certain”, followed by specific chapters detailing what climate changes are likely, the consequential impacts, and the specifics of adaptation and mitigation strategies. in addition to this, dr pittock has a chapter placing climate change in a wider context, which includes stratospheric ozone, land-use change and population growth, and also in an international context, which looks at the kyoto protocol and the national interest of large sectors of the planet. the book includes extensive endnotes, with links to ongoing and updated references and citations. as for peace, the desire for strategies that produce positive net benefit is hard to satisfy when little trust exists between nations. barrie stresses the need to look beyond the kyoto protocol, and, once again, this could not be a more timely discussion as 2009 will end with the conference of the parties (cop) to the framework convention on climate change in copenhagen. the new material in barrie’s second edition, which focuses on investments in large-scale renewables, such as the kind being taken up in california, as well as many smaller scale activities in individual homes and businesses, now being driven by both regulatory and market mechanisms, could serve as a “primer” for the cop participants. perhaps my only disagreement with this book is barrie’s optimism. although his message that climate change is here (and in some areas, might already be having disastrous effects) is clear, he offers hope for the future. he also proposes ideas designed to inspire people to take action, and i hope that he is successful. but, while i wish him and climate change: the science, impacts and solutions “bon chance”, i am myself much less sanguine. pittock says, “all is not doom and gloom: we can save the day” (p. 326). and goes on, “we need to reduce carbon correspondence ann henderson-sellers, department of environment and geography, macquarie university, north ryde, new south wales 2109, australia. e-mail: annhs@science.mq.edu.au polar research 29 2010 139–140 © 2009 the author, journal compilation © 2009 blackwell publishing ltd 139 mailto:annhs@science.mq.edu.au emissions, and we need to do it fast. although we are facing an emergency, with an appropriate allocation of ingenuity and resources, together we can do it”. i fear that my view is that we have, as a species, missed the last ship of opportunity. what is worse, we have also marooned many other species on a warming and changing planet for which we are all ill-adapted. nevertheless, i do very much agree with barrie’s final sentence: “we owe that, at least, to our children” (p. 326). i very much hope that this book will go some way to persuading rascals in politics and elsewhere of the need and urgency of climate change mitigation and adaptation. ann henderson-sellers book review polar research 29 2010 139–140 © 2009 the author, journal compilation © 2009 blackwell publishing ltd140 no job name b o o k r e v i e w por_135 473..474 review of climate change and globalization in the arctic: an integrated approach to vulnerability assessment, by e. carina h. keskitalo (2008). sterling, va: earthscan. 254 pp. isbn 978-1-84407-528-7. in the past decade, much of the research on global environmental change has adopted a new conceptual and methodological framing: vulnerability. this framing draws on decades of prior research—from multiple disciplinary perspectives and traditions—on how people produce, and respond to, conditions in their biophysical environments. the novelty in this framing is the recognition of the need to integrate existing ideas and methods, so as to paint a more holistic picture of the complex problems under study. naturally, these conceptual (e.g., kelly & adger 2000; mccarthy et al. 2001; turner et al. 2003) and methodological (e.g., o’brien & leichenko 2000; luers et al. 2003; schröter et al. 2005; polsky et al. 2007) developments have outpaced the production of empirical vulnerability assessments that employ/operationalize these framings. this book by keskitalo is therefore a welcome addition to the literature on global environmental change, because the author applies the new conceptual and methodological framings to a specific case. her study examines the effects of trends in climate and globalization through a bottom-up, community-based examination of three sectors (forestry, reindeer herding and fishing) in three study areas (the northern reaches of norway, sweden and finland). the research is designed along three dimensions: a focus on vulnerability associated with multiple (two) stressors; a concern with how the vulnerability is mediated by political institutions (“multi-level governance”); and an empirical emphasis on individual people’s perceptions of their vulnerabilities (i.e., a “stakeholder-driven” analysis). in the introduction and chapters 1 and 2, the author contextualizes her work within the historical development of research on human–environment interactions in general, and on the human dimensions of global environmental change in particular. keskitalo notes that her primary (albeit not exclusive) interest in this research is in studying social (rather than biophysical) vulnerability, and in analysing adaptive capacity in terms of both individual and collective potentials and actions, covering both short and long time horizons. the author also argues for the benefit of operationalizing adaptive capacity in terms of political institutions (both formal and informal) that manifest at multiple scales, the concept of “multilevel governance”. keskitalo’s analytical approach is to conduct semi-structured interviews and focus groups with individuals who work in these sectors, and to draw from relevant archival accounts. the next three chapters are devoted to examining sector-specific vulnerabilities. chapter 3 examines forest industry stakeholders in northern sweden and northern finland. chapter 4 assesses the perceptions of change, vulnerability and adaptive capacity among reindeer herding stakeholders in northern norway, sweden and finland. chapter 5 discusses the vulnerability and adaptive capacity among small-scale fishing stakeholders in finnmark county, norway. in these chapters, the reader learns that, for example, globalization has in all cases produced an economic environment that demands correspondence colin polsky, clark university graduate school of geography, 950 main street, worcester, ma 01610, usa. e-mail: cpolsky@clarku.edu polar research 28 2009 473–474 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 473 mailto:cpolsky@clarku.edu continued increases in production and decreases in costs. also common to the three sectors examined is the question of the uncertainty posed by climate change: depending on the particular manifestation of climate change in local places, the impact could be positive or negative. for example, a warmer world might mean greater forest production, but only if the harvesters can successfully capitalize on the shorter winter, which means knowing precisely the new end-date of winter. the reader also learns of differences among the three sectors examined. even though all three sectors are characterized by regulatory and governance influences from multiple scales (local, regional, national and international), the norwegian fisheries case study appears to manifest the most asymmetrical set of regulatory influences. this industry is dominated by a host of national and international regimes that complicate the business of fishing, and, by extension, the process of adaptation by local small-scale fishermen. (in theory, these same institutions could facilitate the process of local adaptation, provided the institutions focus their energies on that process.) by contrast, the forestry and reindeer herding sectors appear to be regulated by a smaller number of institutions, relatively evenly distributed across scales. this book is clearly the product of a thorough and systematic research project. the chapters are organized in a coherent and logical manner. as a result, the reader can readily assimilate the information presented. despite the author’s success in realizing her ambitious scope, there are some shortcomings. for example, the report might have benefited from linking the discussion about present and future adaptive capacities to a more thorough historical account of local adaptive capacities—even if the historical stressors did not include climate change or globalization. such retrospective analysis might uncover anecdotes of adaptation that would validate, in a sense, the hypothesized future adaptive capacities. similarly, even though it is difficult to validate people’s perceptions, the book would have benefited from some discussion of the topics from other people’s perspectives. the introduction reports that some archival sources are used to validate the “perception” data from the interviews and focus groups, but there remains room for a more thorough discussion of the topics discussed by the local stakeholders (e.g., what are the perceptions on these topics of national decision-makers or analysts?). that said, keskitalo’s book already contains an enormous amount of information; these shortcomings could be addressed in a future publication. thus, in sum, this book is a valuable contribution to the literature on the human dimensions of global environmental change. scholars, graduate students and practitioners will benefit from reading and referencing it. colin polsky & prajjwal k. panday references kelly p.m. & adger w.n. 2000. theory and practice in assessing vulnerability to climate change and facilitating adaptation. climatic change 47, 325–352. luers a., lobell d.b., sklar l.s., addams c.l. & matson p.a. 2003. a method for quantifying vulnerability, applied to the agricultural system of the yaqui valley, mexico. global environmental change 13, 255–267. mccarthy j.j., canziani o.f., leary n.a., dokken d.j. & white k.s. (eds.) 2001. climate change 2001: impacts, adaptation, and vulnerability. cambridge: cambridge university press. o’brien k.l. & leichenko r.m. 2000. double exposure: assessing the impacts of climate change within the context of economic globalization. global environmental change 10, 221–232. polsky c., neff r. & yarnal b. 2007. building comparable global change vulnerability assessments: the vulnerability scoping diagram. global environmental change 17, 472–485. schröter d., polsky c. & patt a. 2005. assessing vulnerabilities to the effects of global change: an eight step approach. mitigation and adaptation strategies for global change 10, 573–595. turner b.l. ii, kasperson r.e., matson p.a., mccarthy j.j., corell r.w., christensen l., eckley n., kasperson j.x., luers a., martello m.l., polsky c., pulsipher a. & schiller a. 2003. a framework for vulnerability analysis in sustainability science. proceedings of the national academy of sciences 100, 8074–8079. book review polar research 28 2009 473–474 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd474 invited key note address the cryosphere: an early indicator and global player hartmut grassl, max planck institute for meteorology ice at or below the surface of the planet earth is an important part of the climate system. the solid phase of water has two unique characteristics which make it both an early indicator of climate change and a global player. first, if warmed to the melting point at o t , higher air temperatures and/ or higher long-wave back radiation just increase the melting rate but not as with all other surfaces the temperature, which stays at 0°c. small ice caps and mountain glaciers thus become early indicators of a changed climate. second. if seawater is cooled to the freezing point at about 1.8"c. the sea ice formation process ejects salt causing the denser water to sink, thereby filling the global ocean interior with very cold water. the location where most of this deep convection occurs is strongly dependent on the freshwater balance and thus on the average salinity of ocean basins. present ocean configuration and ocean topography, as well as precipitation distribution, make the northern north atlantic more saline than any other high latitude ocean part and thus the site with most of this deep water formation. sea ice formation is therefore of high significance for the european climate. since it drives the near surface warm north atlantic current northward off the european coast in compensation for southward deep water flow in the western atlantic, north western europe is warmer by about 4°c than the same latitudes on the eastern pacific coast of america. since i restrict myself to climate-related aspects of the cryosphere, i will not speak about reactions of the biosphere and high latitude populations to global change, but i will include cryospheric processes outside the polar latitudes. a few facts: the cryosphere 0 is the largest freshwater reservoir: 98% of all freshwater is fixed in the antarctic and green land ice sheets as well as in the other small ice caps and mountain glaciers; 0 contains the brightest natural surface: fresh powder snow reaches an albedo of about 90% as compared to about 15 to 20% for grassland; 0 is responsible for a positive feedback: melting of high albedo surfaces (snow and ice) increases absorption of solar radiation which in turn increases temperature and accelerates melting of nearby snow and ice surfaces; 0 emits least heat to space: the low surface temperatures of greenland and antarctica cause the lowest emissions to space both in winter and summer for their respective hemispheres; 0 insulates the ocean from heat loss: sea ice reduces all three heat losses of a surface (long wave net radiation, sensible heat flux, latent heat flux); the latter two to a small fraction of the values for an open ocean area; 0 fixes large amounts of carbon dioxide ( c 0 2 ) and methane (ch4): organic material in permafrost is to a large part emitted as co? and ch4 after the melting of permafrost; 0 changes by more than a factor of two within an annual cycle: for example, northern hemi sphere snow cover reaches 46.5.106 km' i n late january and is lowered to 3.9.10hkm2 in september; 0 creates the cold interior of the global ocean: antarctic bottom water and north atlantic deep water formed by deep convection are the main water masses of the global ocean, with tem peratures mostly below about 3°c even in tropical latitudes. some recent findings this selection of examples tries to avoid overlap with other presentations in this volume. therefore, the following three examples will be briefly presented: remote sensing of mountain glacier retreat; stability investigations of the thermohaline grassl 1999: polar research 18(2), 119-125 119 t ' 0 n e o . $ -lo c m . c v . p 4 0 m '; -20 2 -30 .e y 2 -50 4 -70 fig. i. glacier retreat in the austrian alps: ( a ) relative change in area in 1992 versus area i n 1985 as a function of glacier area; (b) change in area with exposition (from paul 1997. with perrnigsion of author). i + t 4 . 8 % : x 1 2 5 a $ 0 8 x 4 o o ; + * " $ b o n x ; : $ * a x 0 x v 0 stubai nollh 0 stuba south + otaal north v omal east x zillerlal *average v a otaal west t o + ' ' ' stubainorth stubaisouth otaalnollh otaal west ornaleast overturning in the atlantic; and selection of a sea ice rheology code best suited for global climate models. alpine glacier retreat: small valley glaciers react comparably rapidly to temperature and precipita tion changes. their retreat depends strongly on their length. mean slope, ratio of accumulation to entire surface area and orientation. landsat images with sufficiently high spatial resolution exist since 1973 for a trend analysis. as one of my students (paul 1997) has shown, for many glaciers in the eastern alps, the 19 year period from 1973 to 1992 was one of strong retreat with clear dependencies on orientation and size of the glaciers. as fig. 1 demonstrates, even the 1985 to 1992 period gave clear signals. the main reason for the retreat in this area with no significant change of annual precipitation during the recent decades was a rather rapid warming. thermohaline circulation changes in the atlantic: at present the meridional overturning of the atlantic drives the so-called global ocean con veyor belt. palaeoclimatic evidence points to rapid changes of the deep water formation rate in the high latitude atlantic, the core region of the conveyor belt. as also shown by modelling studies (e.g. rahmstorf 1996) the stability dia gram (see fig. 2 ) of the conveyor contains a large 120 the cryosphere: an early indicator and global player -0.1 0 0.1 freshwater forcing (sv) f i g . 2. north atlantic deep water (nadw) formation rate ;is a function of additional freshwater input into the atlantic north of 30 s (modified from rahmstorf 1999, with permission of the author). solid lines show stehle equilibrium states: unstable states are dotted. note the strong hysteresis as well a h the different mechanisms responsible for the cessation ot deep water formation. transition mechanisms include: a ) local convective instability; h) polar halocline catastrophe: c) advective spin-down: and d) start-up of convection and nadw formation. hysteresis. the addition of freshwater north of 30's in the atlantic only 0.1 sverdrup (1 sv = 1 0 h m 3 s ' ) is sufficient stops deep water formation, which will only start again if all the additional freshwater input is removed. the cryosphere (for example, due to additional melt water from decaying ice sheets) has exerted this aug feb aug feb aug feb aug feh aug 1990 1991 1992 1993 1994 a o d f a j month (4 24c g 35 25 .2 20 2 15 e 5 c 30 tj x c 10 x o 5 1 2 3 4 5 6 7 8 9 1 0 1 1 12 month fig. 3. (a) first multi-year time series of sea ice draft i n fram strait: ( h ) the annual cycle; and (c) the maximum draft during different months (t. vinje and n. nordlund, pers. cornm.). ice thickness = draft x 1.136. ice export per year = ca. 2.8 x 10'km'. influence in the past, but a change in precipitation a n d o r evaporation over the atlantic would also suffice. much more research is needed to find out t u h k 1. similarities and contrasts among polar regions. nh and sh indicate whether the intersection of a cryospheric element w i t h a climate process is specific to the northern or the southern heniisphere, or occurs i n both. climate processed cryospheric elements ice glaciers. frozen rivers. frolen ice sheet\ \helve\ ice caps sea ice snow laker ground sen level change deep water tormatioii surtace energy halance albedo latent and wnsible heat ole.inil \urt.ice buoyancy f l u x precipitation melting/ahldtion freezing/accumulation lceherg calving soil moisture (run-off) radiative processes (through changed atmospheric composition) nh trend nh sh. catastrophic sh nh, sh sh nh sh nh nh sh nh, sh nh.sh nh.sh nh n h , s h n h , s h nh nh nh, sh n h , s h nh.sh nh nh nh nh nh grass1 1999: polar research 18(2). 119-125 121 tahl 2. the state of observational data for the northern (nh) and southern (sh) hemispheres, and international research programmeslgroupslinstitutions that have contributed or will contribute to the data. dindicates absence of necessary data; d+ indicates availability of some data; do indicates lack of information on the data required. climate processed ice ' glaciers. frozen rivers, frozen cryospheric elements ice sheets shelves ice caps sea ice snow lakes ground sea level change dnh: do/ magics magics ismass sh: d waiss deep water formation d frisp surface energy balance. albedo nh: do sh: d + gewex latent and sensible heat d frisp oceanic surface buoyancy flux. precipitation melting/ablation. freezing/accumulation ddnh: do/ magics frisp magics ismass sh: d wais iceberg calving do/+ do/+ soil moisture (run-off) radiative processes (through changed atmospheric composition) nh: d + acsys clivar sh d ianzone aspect d + d+ do acsys gewex gewex n h . d o d+ d+ acsys ecmwf ecmwf sheba ncep ncep aspect wcrp sh. d d snowdnft d + do nh.acsys nh. sh. aspect acsys wcrp sh: ianzone aspect do d o gewex gewex do ecmwf d o gewex d igac whether the global warming by an enhanced greenhouse effect would bring us nearer to such a rapid change. sea ice dynamics in climate models: the coupling of ocean sea ice and the atmosphere as well as of soil, vegetation and atmosphere is among the major challenges of climate modelling. sea ice dynamics is an important part in this coupling. the sea ice modelling panel (siomp) of the arctic climate system study (acsys) of the world climate research programme (wcrp) conducted sea ice dynamics model intercom parisons and found that only the viscous-plastic model could reproduce the observed sea ice thickness distribution in the arctic (lemke et al. 1997). global climate models therefore should adopt this code for a more realistic representation of sea ice in global coupled climate models. the arctic climate system study the different projects of wcrp are normally global since both the atmosphere and the ocean circulate globally. only the arctic climate system study (acsys) has a regional focus, i.e. i t 122 t h e cryosphere: an early indicator and global player tuble 3. the state of modelling for the northern ( n h ) and southern ( s h ) hemispheres. and international research programmed groups/institutions that have contributed or will contribute to modelling efforts. m + indicates that some modelling activities are underway; mindicates insufficient modelling efforts; mo indicates lack of information on sufficient modelling activities. climate processes/ ice glaciers. frozen rivers, frozen cryospheric elements ice sheets shelves ice caps sea ice snow lakes ground sea level change mo/+ nh mo eismlnt magics sh m deep water formation m + m + frisp acsys i anzone i anzone eismint ice-ocean coupling surface energy habdnce albedo mo m + mo eismint acsys wgne: lanzone albedo lx = a (t. surface type) latent and sensible heat m+ m+ mo fnsp acsys wgne, eismint ianzone subgnd i anzonr parameter ization (land) oceanic surface buoyancy flux. precipitation mo melting/ahlation, mo/+ m+ nh:mo m + mol+ freezingiaccumulation eismint frisp maglcs acsys acsys eismint sh: mianzone tanzone ianzonr iceberg cdlvlng mm soil moisture (run-off) mo radiative processec (through wgne changed atmosphenc composition) mo gewex m + mo ecmwf ecmwf ncep mo m o gewex wgne mo clivar acc concentrates on the arctic ocean and sea ice. its objectives are: 0 to provide the scientific basis for the representa tion of the arctic region in coupled global atmosphere-ocean models; 0 to develop an effective climate monitoring scheme in the arctic; 0 to carry out scenario computations for specified large-scale atmospheric conditions, in order to evaluate possible impacts of climate change in the arctic region. started in the early '90s. a good example of early achievements is provided in fig. 3, which displays the first multi-year time series of sea ice draft i n fram strait measured with upward looking sonars mounted on top of ocean moorings. it underlines the importance of sea ice export through fram strait into the atlantic. 2800 km3 are exported per year which is if compared to river run-off roughly 20 times the discharge of the congo river. astonishingly, the thickest ice is exported in summer and interannual changes are large, spanning the range from about 2000 to 4000 km3, acsys formally implements its goals since 1994 although some scientific activities had already thus contributing to large salinity anomalies in greenland sea waters. grass1 1999: polar research 18(2), 119-125 123 table 4. existing international programmes/projects/activities. status: i = implementation; 1p = implementation plan exists. acronym full title hemisphere status focus sponsoring institution acsys arctic climate system study iabp international arctic buoy programme ipab international programme of antarctic buoys ansitp antarctic sea ice thickness project ianzone international antarctic zone program calm circumpolar active-layer monitoring programme gcd global geocryological data base magics mass balance of arctic glaciers and ice sheets i n relation to the climate and sea level changes clivar-d5 southern ocean thennohaline aspect ismass wais* frisp* eismint" crysys* circulation focus in clivar climate level antarctic sea-ice processes and ice sheet mass balance and sea nh nh sh sh sh nh both both, focus on nh sh sh sh i i i i i coupling of the circum-antarctic ocean and the atmosphere i active layer thickness in continuous permafrost areas i retrieval, documentation, archiving and distribution of permafrost data 1 circumpolar mass balance studies arctic ocean circulation and sea drifting buoys on sea ice drifting buoys on sea ice sea ice thickness from upward ice looking sonars ip southern ocean variability and ip ip climate variability and environment change sheet 200 years of past antarctic climate mass balance of the antarctic ice west antarctic ice sheet sh i understanding the dynamics of the initiative wais filchner-riinne ice shelf project sh i understanding ice shelf-ocean european ice sheet modelling sh i understanding the dynamics of ice initiative sheets, including ice shelves canadian contribution to nasa's nh '? use of the cryosphere to monitor eos on the cryospheric system interaction climate change wcrp operational and wcrp wcrp scor (icsu) research institutions ipa (rcsu) ipa (icsu) iasc wcrp scar (icsu) scar (icsu) usa consortium european consortium mainly european consortium canadian initiative *national or multi-national activities with research topics falling within the clic domain (incomplete). another achievement is the sea ice model intercomparison which has led to a recommenda tion for climate model sea ice codes (lemke et al. 1997): modelled sea ice dynamics using the viscous-plastic model are nearest to observations of sea ice extent and thickness and should thus be adopted for global coupled climate models. no overlaps, but still some gaps soon after the start of acsys, discussions for a broader approach of research on climatically relevant cryospheric processes were initiated inside and outside wcrp. an expert meeting on cryosphere and climate organized by wcrp and hosted by the british antarctic survey in cam bridge, uk, from 3 to 5 february 1997, developed recommendations for wcrp concerning the broadening of climate-related cryospheric research (wcrp 1998). one of the main findings was that despite the large number of programmes/projects/activities, there were nearly no overlaps but still some gaps i n climate-related research of cryospheric processes. this is detailed i n tables i to 3, which first show the processes relevant i n the different cryospheric elements and the contrasts between the hemi spheres, and then point to data gaps and insuffi cient modelling. the major recommendation to wcrp was that a global activity on cold regions and climate within wcrp should be developed whereby already successfully implemented pro jects should not be disrupted. the recommendations of the meeting led to the establishment of a task group on climate and 124 the cryosphere: an early indicator and global player cryosphere (clic) by the joint scientific corn mittee (jsc) for wcrp. by seasonal climate anomaly predictions related to tropical sea surface temperature anomalies, which are available now from global modelling centres, shifts the main climate research topics to other processes and to longer time scales. cryospheric processes thus come more into the focus of climate research. for example. improved seasonal predic and cryosphere: a wrcp initiative with the establishment of the jsc/acsys task group on climate and cryosphere (clic) at the nineteenth session of jsc in cape town. south africa, in march 1998, a global climate and cryosphere project of wcrp became highly probable. that the clic task group is also charged with the formulation of a coordination plan can easily be understood if one looks at table 4 which lists existing international programmes/ projects/activities engaged i n climate-related cryo spheric research. coordination will be facilitated by the fact that many of the ongoing activities are sponsored by committees or associations of the international council for science (icsu) which is also a sponsor of wcrp, i n addition to wmo and unesco's ioc. the two major goals of clic as far as i can see them now will be: 0 understanding climatically relevant cryospheric processes, including their role as early indica tors of climate variability and climate change; 0 understanding and predicting to the extent possible the influence of the cryosphere on global climate. a first outline of the science plan was drafted at the first clic task group meeting which took place i n utrecht, the netherlands, from 8 to 1 1 july 1998. the report of the meeting, including the outline, will be discussed by the acsys scientific steering group i n tokyo i n november 1998 before i t is submitted to the jsc for wcrp in march 1999 in kiel, germany. outlook the improved understanding of seasonal to interannual climate variability, as it is expressed tions i n the asian monsoon area may need better data on central asian snow cover. the under standing of the arctic oscillation depends on improved data and modelling of sea ice ocean atmosphere interaction; and the understanding of the influence of the enhanced greenhouse effect on global thermohaline ocean circulation needs, in addition to oceanographic information, data on the long-term behaviour of snow extent, run-off or calving from ice sheets. it is time for clic, and since all institutions implementing or planning projects on climatically relevant cryospheric processes have indicated their preparedness to cooperate, i see no major obstacles for the proper coordination of the existing activities and the filling of the gaps identified i n a new global wcrp project climate and cryo sphere. references lemke, p.. hihler, w. d., flato. g., harder. m. & kreyrcher, m. 1997: on the improvement of sea-ice models for climate simulations: the sea ice model intercomparison project. ann. clacid. 25, 183-1 87. paul, f. 1997: changes of glacier area i n the austrian alps hetween 1973 and 1992 derived from landsat data. m a x plunck institute for meteorology report no. 242. rahmstorf. s . 1996: on the freshwater forcing and transport of the atlantic thermohaline circulation. clirn. dyn. 12. 799-8 i i. rahmstorf. s. 1999: decadal variability of the thennohaline circulation. i n a. n a v m a (ed.): eryond el niao: clecudul and inrrrdrcadal c./imatr variubilin. pp. 309-332. berlin: spring er. wcrp (world climate research programme) 1998: 0rgoni:u t i o r i of internatiorml/y co-nrdinated resenrch in cr?.osphere and clitnutr: proceedings of a meeting oj r.rperl.7 or1 crysphere arid climate. cambridge. uk. 3-5 february 1997. r . g. barry. ed. wmo/td no. 867. geneva: world meteorological organization. grass1 1999: polar research 18(2). 119-125 i25 bookreviews25(2).indd 181polar research 25(2), 181–188 widely read and acknowledged. however, the fi rst and last chapters are also an interesting read and give a nice basis for evaluating the biological and ethnographic material presented in the volume’s middle section, although now and again they are redundant. the book contains an interesting and eclectic collection of black and white illustrations including portraits, historical photographs, and technical and biological drawings. otto fabricius was a cleric, philologist, naturalist and ethnographer. much of his scholarly work stems from the relatively short period of his life spent as a missionary in greenland (1768–1773). his observations during these fi ve years and the experiences he had with greenlandic people clearly left a great impression on fabricius that lasted until his death. unlike many missionaries of his time, fabricius left the european colonytown where he was posted and lived in a greenlandic inuit community. he resided in a house built of stones, turf and timbers and learned the language and the ways of the people. much of their hunting culture revolved around knowing the habits of seals, and hence the people were a wealth of knowledge to fabricius in his faunal and ethnological studies. fabricius is undoubtedly best known for his publication fauna groenlandica (1780), but the work translated by kapel in this book, published a decade later (1790–91), allowed fabricius to expand greatly on the seal material presented in the earlier book. fabricius’s detailed description of the seals of greenland focuses fi rst and foremost on the harp seal or greenland seal (phoca groenlandica), describing: nomenclature; appearance and morphology; distribution (occurrence); behaviour; variation in occurrence and movements; breeding; feeding; predators; hunting methods; utilizabook reviews review of otto fabricius and the seals of greenland. meddelelser om grønland: bioscience 55, by finn o. kapel (2005). copenhagen: danish polar center. 150 pp. isbn 87-90369-77-7. kit m. kovacs norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, kovacs@npolar.no. in this three part volume finn kapel presents us with 1) a brief biography of fabricius, 2) a translation of his treatise on the seals of greenland and, fi nally, 3) a refl ection on the contribution of fabricius as a seal naturalist/scientist. i concur with dr kapel’s belief that the key paper is the second one. this work on greenland’s pinnipeds has until now been available only in danish and german and certainly deserves to be more skull of the “hook-snouted seal”, now known as the grey seal (halichoerus grypus). the drawing illustrated fabricius’s detailed description of the seals of greenland (1791). (reproduced with permission of the danish polar center.) portrait of otto fabricius. (reproduced with permission of the danish polar center.) 182 book reviews tion; parasites; and synonyms. ringed seals (pusa hispida), harbour seals (phoca vitulina), hooded seals (cystophora cristata) and bearded seals (erignathus barbatus) are presented similarly, although more briefl y. fabricius also gives short synopses of four additional “species” reported to him by the greenlanders. three of these animals are either mythical beasts or some sort of biological oddity such as albino specimens. the fourth species summary is the fi rst scientifi c account of the grey seal (halichoerus grypus), which fabricius describes primarily from material in his possession from an island off the danish coast. given the era in which fabricius was writing, his restricted time in greenland, and limited travel in the north, his biological accounts are remarkably insightful. occasionally, they are defi nitively incorrect, such as when he says, “as for the breeding of the harp seal, the matingtime is beyond all doubt in august” when in reality harp seals mate in march. but fabricius can be forgiven for using the size of the embryo in september to back-calculate the time of mating: delayed implantation was unknown in the 1700s. other small slips can be similarly accounted for. he is probably not credited as often as his work warrants; perhaps this book by finn kapel will help correct this situation. if allen’s history of north american pinnipeds (1880) or similar books are on your shelf, otto fabricius and the seals of greenland undoubtedly also deserves a place there. references allen, j. a. 1880: history of north american pinnipeds. a monograph of walruses, sea-lions, sea-bears and seals of north america. washington, d. c.: u.s. geological and geographical survey of the territories. fabricius, o. 1780: fauna groenlandica. (fauna of greenland.) copenhagen(?): j. g. rothe, hafniae & lipsiae. fabricius, o. 1790–91: udførlig beskrivelse over de grønlandske sæle, første og andet stykke. (detailed description of the seals of greenland, parts one and two.) copenhagen: skrivter af naturhistorie-selskabet. review of le monde polaire, mutations et transitions, under the direction of mariefrançoise andré (2005). paris: ellipses– carrefours. 187 pp. isbn 2-7298-2683-1. in french. bernard lefauconnier place du mollard, f-38700 le sappey en chartreuse, france, b.lefauconnier@wanadoo.fr. as mentioned on its back cover, le monde polaire, mutations et transitions comprises part of a collection (carrefours) intended for students of geography, history and the social sciences as well as for a wider public interested in understanding the changes our world is undergoing. other volumes in the series concern, for example, water in the arab world, large cities of north america and international commerce. twelve authors have collaborated on the book. the work is divided into two parts, made up in total of 11 chapters and six brief inset texts. the fi rst part is supposed to present some general aspects of the subject, regional aspects being introduced in the second part. seven of the book’s 11 chapters concern the indigenous peoples of the circumpolar region and constitute the heart of the volume. chapter 3 explores how the inuit conceive of—and are integrated with—their environment. chapter 4 discusses the transition from a subsistence economy to the present situation in the canadian arctic, focussing on nunavik, northern québec. major social transformations are described in chapter 10, with examples from the central canadian arctic. chapter 5 describes the emergence of the sense of an inuit identity, the creation of the inuit circumpolar conference and the building of inuit managerial and administrative competence, especially in the nunavut and nunavik territories, northern canada. chapter 7 concerns the transformation of greenlandic society. the situation of the saami, the subject of chapter 8, is unusual in that this population is represented in four countries: norway, sweden, finland and russia. the relationship between the saami and the norwegian state is described. the small-numbered indigenous ethnic groups—mainly reindeer herders—of the russian arctic are briefl y presented in chapter 9. only two chapters are devoted chiefl y to the 183polar research 25(2), 181–188 physical environment: chapter 1 presents a review of some recent research on the melting of glaciers and the related sea level rise while chapter 2 discusses the impacts of climate change through the metamorphosis of polar landscapes. one chapter (6) describes the development of polar tourism and chapter 11 summarizes past and present scientifi c activities in the antarctic. the limited space allotted to the environment in this book is regrettable. impacts related to climate change are not confi ned to glaciers and landscapes. in a book with academic intentions, references to the arctic climate impact assessment and the arctic monitoring and assessment programme would have been minimally necessary. in chapter 1, one of only two chapters devoted to the environment, some of the research results that are discussed are erroneously interpreted. for example, arendt et al. (2002) estimated the contribution to sea level of alaskan glaciers from the mid-1950s to the mid-1990s to be 0.14 ± 0.04 mm per year. this is equivalent to 5.6 ± 1.6 mm over the period, not 5 cm. another example is where the chapter’s author (incidentally, also the book’s editor), referring to rignot et al. (2003), writes that patagonian glaciers contribute even more than alaskan glaciers to sea level rise. in fact, rignot et al. said that the contribution from the patagonian glaciers is larger than that of alaskan glaciers per unit area. this is an important distinction. finally, the chapter mentions glacier surging but this phenomenon is evidently not understood by the author. there are other fl aws. chapter 6 takes into account the local and regional environmental impacts of tourism but does not mention the contribution to global pollution generated by the transportation of voyagers from low latitudes to the polar areas. in two places—a short inset in chapter 10 and a section heading in chapter 4— the use of the phrase “welfare state” (état providence) seems inappropriate. the texts discuss social and economic transformations and largescale interventions by the canadian central power. the “welfare state” must have been developed to try to counter-balance negative social effects of these transformations and is not in itself the cause of these negative effects. this is a strange book. the title claims to embrace the polar world but only a single chapter concerns the antarctic. the chapters discussing the environment merely skim lightly over a narrow slice of this important topic, without any real look at current climatic changes or the fact that the arctic and antarctic have already been affected by pollution, including ecotoxins, coming from sources elsewhere in the world. even with these drawbacks le monde polaire has value: there are few books presenting a broad picture of circum-arctic peoples. social, economic and geopolitical problems and the similarities and differences in the relationships between far northern indigenous peoples and the modern states that encompass them are briefl y but, in general, clearly described. i was particularly captivated by the subject of chapter 3—“corps inuit, espace géographique et cosmologique”, which opened for me, as an occidental scientist, a new window on the arctic and enriched my vision of it. references arendt, a. a., elchemeyer, k. a., harrison, w. d., lingle, c. s. & valentine, v. b. 2002: rapid wastage of alaska glaciers and their contribution to rising sea level. sciences 297, 382–386. rignot, e., rivera, a. & cassasa, g. 2003: contribution of the patagonia ice-fi elds of south america to sea level rise. science 302, 434–437 review of the north pole, by kathan brown (2004). san francisco, ca: crown point press. 504 pp (xi-xvi). isbn 1891300-18-0. thor b. arlov research and innovation unit, norwegian university of science and technology, no-7491 trondheim, norway, thor.arlov@ntnu.no. at fi rst glance a medium brick sized book entitled the north pole seems a promising read to anyone interested in the arctic, such as this reviewer. unfortunately it does not quite deliver according to expectations, presuming you expect solid information about the polar region. if, however, you are particularly interested in the personal experiences of arctic tourists with a dash of environmental concern, this book may not be a complete waste of time. the author kathan brown is the founder and 184 book reviews director of a renowned san francisco-based fi ne art printing press and publishing house. she has previously published various books on art and artists. however, her professional or personal connection with the polar regions are, as it were, shrouded in northern mists. the introduction to the north pole is not very helpful about her motives for writing this book. it appears she took part in a trip to the north pole sponsored by the american museum of natural history aboard the russian nuclear powered icebreaker yamal in 2002. the following year, she spent a week on a coastal cruise around svalbard. her experiences during these two trips have obviously inspired the book. in addition she has read a number of works about various arctic subjects and talked to some knowledgeable people, but to call this a thoroughly researched book would be stretching it. admittedly, brown seems to have no pretences in this direction. the north pole is voluminous in pages—a little more than half a thousand. the genre is a bit diffi cult to decide as the author mixes forms. since the voyage seems to be the structuring element, i suppose the book might be placed in the travel literature category. following a brief introduction that attempts to explain the somewhat odd composition of the book, there are eight main chapters. the fi rst seven are devoted to the north pole trip on the yamal. each of them is divided into three sections: a personal narrative by the author; excerpts from the journal of fridtjof nansen from the fram expedition; and a conversation with various people rendered in verbatim form. the last chapter is on the visit to svalbard and also contains a conversation, but— quite understandably—no excerpts from nansen. in between there are more than 100 photographs, the vast majority taken by the author herself. to the extent that there are any main themes at all, the issue of climate change and the question who was the fi rst on the north pole (if indeed peary cheated) recur frequently with slight variations throughout the book. if i were to be very polite i would call this unusual lay-out interesting, but to be honest i am rather put off by what seems to be a lack of serious effort making this book. the author’s own, original contribution represents the lesser part of the manuscript. the “journey” sections written by brown make up some seventy pages, or less than 15 % of the book. the photographs, also the work of brown, constitute nearly a quarter of the book. of the remaining 60 %, the excerpts from the journal of nansen fi ll almost 100 pages. the conversations or interview sections, where brown acts as “moderator”, occupy over 150 pages. at the end of the book there is a rudimentary time line, a short bibliography and a decent index. the only map in the book is a poor sketch of the arctic. although neatly organized, this book is in effect a compilation of somewhat disparate elements. by themselves the journey sections work fairly well; brown is a good observer and masters the style of a well-read journalist. she makes a pretty good job of popularizing science. this is the kind of prose one might expect to fi nd in for example national geographic: a personal account supplemented by factual information, or vice versa. the conversation sections function less well. their consistently verbatim form leaves the question open whether editing has taken place or not. anyway, stronger editing would have been desirable—considerable parts of the conversations are just plain small talk between fellow travellers. i kept wondering why the reader is invited to listen in. some of the contributors have more to offer, but the knowledge and capacity of participants like, for instance, arctic climate impact assessment director gunther weller and scott polar research institute archivist bob headland, could have been exploited far better in more elaborate interviews. in general, brown does not seem to distinguish between the substantial and the trivial in her role as moderator. for example, rendering an exchange of opinions concerning rock bands or suvs leaves me, in this context, cold. a more selective approach would certainly not have been amiss. nansen’s journal of his and hjalmar johansen’s dramatic attempt to reach the north pole from fram and their subsequent wintering on franz josef land in 1895–96 is a classic in arctic literature, but should rather be read in the original and in extenso. brown’s excerpts seem out of context and do not lend her account authority—just extra pages. i feel the use of nansen borders on literary theft when the author does not even make the effort of paraphrasing or commenting. finally, the photographs are for the most part unimpressive and appear to be ordinary amateur snapshots. considering the author’s professional background the reproduction is disappointing; the colours seem washed out and the subjects are fre185polar research 25(2), 181–188 quently unsharp. variations on ice fl oes are only interesting to a certain point, which brown oversteps. it does not make things better that there are no captions to the pictures, leaving the reader to guess when, where and why they were taken. in all fairness, kathan brown’s the north pole is probably not intended for well-read polar enthusiasts. it is indeed hard to imagine that readers of polar research will fi nd very much of interest in this book. it is simply too superfi cial with regard the factual parts and has too little to offer in literary terms. in my opinion, neither the gracious contributions of some prominent savants of the arctic nor the extensive quoting of nansen’s diary help salvage this north pole voyage from wreckage. at the uttermost ends of the earth: the physiology of polar fi shes, edited by anthony p. farrell & john f. steffensen (2005). amsterdam: elsevier. 396 pp. isbn 0-12350446-5. andrew clarke biological sciences, british antarctic survey, high cross, madingley road, cb3 oet cambridge, uk, accl@bas.ac.uk. ecologists and physiologists have always been interested in organisms living in extreme environments because of the light they shed on fundamental problems, and the general public has long been fascinated by animals living in climates so inhospitable that unprotected humans would rapidly perish. the pioneering physiologists of the early 20th century had quickly recognized that teleost fi shes with their dilute blood would have real problems in the cold waters of the polar regions, and when johan ruud collected the fi rst scientifi c specimens of an icefi sh he was able to confi rm that there really did exist a group of polar fi shes with no blood pigment. the scene was thereby set for an exploration of the physiology of polar fi shes, and this remains a vibrant fi eld of research to this day. the latest volume of the prestigious fish physiology series brings together a group of distinguished workers in the area of polar fi sh and provides a state-of-the-art survey of our understanding of the physiology of a group of organisms that have successfully adapted to one of the most physiologically challenging marine environments on the earth. the opening chapter (devries & steffensen) provides a brief overview of the marine environment of the polar regions, emphasizing the marked differences between the arctic and antarctic as much as their similarities, and thereby defi ning an important theme for the rest of the book. as well as differences in topography, bathymetry, riverine input and oceanography, attention is drawn to the very different tectonic, climatic, glacial and evolutionary histories of the two polar regions. the latter are fundamental to understanding the very different fi sh faunas of the arctic and antarctic, which are described in exemplary fashion in the second chapter by møller, nielsen & anderson. it is refreshing to see due attention being paid to the systematic and biogeographic aspects of the fauna in a volume devoted primarily to physiology, for this is essential to any complete understanding of evolutionary aspects of the physiology. the systematic treatment also covers all depths, thereby providing a broad context for the traditional (but not universal) concentration by physiologists on the more easily sampled shallow waters. the physiological chapters start with a thorough review of current knowledge of the metabolic biochemistry of polar fi shes by pörtner, lucassen & storch. the main themes of this chapter are the central role played by oxygen in shaping both thermal limits and lifestyle, and the trade-offs inherent in the utilization of energy in a strongly resource-limited environment such as the polar seas. the strengths of this chapter are the way physiological processes are set in an environmental context, the use of a wide range of model organisms, and the links between physiology and ecology. antifreeze proteins and freezing avoidance are reviewed by devries & cheng. the physiological challenge to teleost fi sh living in polar regions was recognized in the 1960s: even with an elevated blood salt concentration, polar fi sh are under cooled by almost 1k. whilst this may seem a small interval, because polar oceans contain ice crystals freezing of these fi sh would be inevitable in the absence of a protective mechanism. the existence of antifreeze glycoproteins and proteins in polar fi sh was quickly established by elegant work by art devries himself, but almost four decades later we are still unravelling the complexities of this system. in addition 186 book reviews to providing a masterly summary of the classical work, the authors also discuss areas of active current research making this the best current review of freezing avoidance in polar fi sh. in the next chapter steffensen concentrates on the respiratory system and metabolic rate; this chapter is thus closely allied to the earlier one by pörtner and colleagues but takes a quite different perspective by concentrating on the organismal rather than the molecular level. steffensen revisits the arguments over the existence of metabolic cold adaptation (mca) in polar fi shes, and does so in a thorough and balanced manner. once a fi sh has taken up oxygen, it then needs to move this oxygen around the body and the circulatory system is described by axelsson. a major factor here is the increase in blood viscosity at low temperature, and it is likely that selection for reduced circulatory costs coupled with the increased solubility of oxygen at low temperatures is what drove the evolution of reduced hematocrit in many polar fi shes and the complete loss of haemoglobin in one group, the icefi sh family channichthyidae. a key feature of this chapter is the discussion of the control of heart rate, setting the antarctic notothenioids in the wider context of non-polar fi sh. wells covers blood gas transport and haemoglobin, principally from studies of notothenioids but also setting the results in a wider context. wells also revisits the topic of mca, coming to a less defi nitive conclusion than steffensen. davison describes the skeletal musculature and locomotion, again principally based on studies of notothenioids. data are compared with warmer water fi sh and the differences related to ecological factors such as growth rate and buoyancy. in exploring the various ways in which temperature may limit muscle performance in polar fi sh, davison also discusses the limitation of mitochondrial atp supply, which links this chapter nicely to that by pörtner and colleagues. the fi nal chapter in the book is an authoritative review of the nervous system of polar fi shes by macdonald & montgomery. how does this volume rate overall? i believe it succeeds in providing a thorough, timely and authoritative survey of the physiology of polar fi shes. it will fi nd a place in my library and i have already found myself making extensive use of it. it is a pity that not every author has taken the opportunity to cover both arctic and antarctic studies, for the book does tend to concentrate on studies of notothenioids in many places. important and interesting as these fi sh are, they are confi ned to the southern hemisphere and physiologists have much to learn from thorough comparative studies. nevertheless this is an excellent summary of current knowledge and will remain for some time the place to go to learn about the physiology of fi shes living at high latitudes. review of the north pole was here: puzzles and perils at the top of the world, by andrew c. revkin (2006). boston: kingfi sher. 128 pp. isbn 0-7534-5993-0. helle v. goldman norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, goldman@ npolar.no. ever wondered what the men’s toilet at camp borneo, a temporary russian camp on the ice about 96 km from the north pole, consists of? in the north pole was here, andrew revkin reveals this—“a waist high igloo-style wall of ice blocks” (p. 16)—and other details of the fi eld conditions experienced by scientists who carry out research near the very top of the world. using revkin’s own visit to the north pole environmental observatory—a science camp set up every year on the ice about 48 km from the north pole—as a jumping off point, the book describes the arctic and our past and ongoing efforts to understand it. climate change is a major theme. other topics, like early exploration of the region and the earth’s shifting magnetism, are also covered. in an enchanting chapter called “the imagined pole”, revkin describes early notions of the far north. we learn, for example, that in ancient hindu / buddhist cosmology, the stars in the sky were tied by ropes of wind to the north star, which was positioned above a gigantic mountain that constituted the world’s centre. four landmasses, divided by great rivers, lay around that centre. three thousand years ago, greek historians supposed that there was a society of “hyperboreans”: “an immortal race of people who lived in happiness and warmth beyond the source of the north wind” (p. 28). (this is sure to raise 187polar research 25(2), 181–188 a smile from readers who, like me, reside north of the arctic circle.) as late as the 19th century some maintained that the earth was hollow, with large openings into the interior at the north and south poles. according to another tenacious and surprisingly recent theory, the north pole was topped by a huge iron cone, which was the source of the planet’s magnetism. the bulk of the north pole was here is set in the present. revkin focusses his account on the scientists who undertake polar research, how they do it and the diverse challenges they face. one chapter begins with this riveting opening: “six of the world’s leading experts at solving arctic riddles are on their knees on the sea ice thirty miles from the north pole, stumped by three broken bolts” (p. 89). the chapter goes on to relate how the bolts were replaced and the winch repaired, and how the equipment contributes to our knowledge of the ocean, atmosphere and climate in the arctic. the heroes of revkin’s book are polar scientists and the divers, technicians and others who work with them. in the harsh environment of the arctic, research teams must combine “the brainpower of scientists with the brute strength of furniture movers, the wile of small-town mechanics, the courage (or recklessness) of extreme athletes, and the willingness to carry a shotgun to ward off polar bears” (p. 92). without oversimplifying its subject matter, the north pole was here makes science accessible to the nonspecialist reader. the slim book is aimed particularly at young adults but will also appeal to their parents. the chapters are short, the type is large and the text is amply illustrated with photographs, diagrams, maps and other illustrations. excerpts from new york times stories relating to the arctic (about half by the author) are sprinkled throughout the book. an award-winning journalist, revkin has been reporting on environmental issues for the new york times for over a decade. some readers may recognize the author’s name from his recent coverage of the bush administration’s attempt to stifl e jim hansen, director of nasa’s goddard institute for space studies, after hansen publicly called for prompt reductions in greenhouse gas emissions. the north pole was here is well timed: 2007-08 is an international polar year, during which scientifi c resources around the world will be concentrated on the arctic and antarctic. its antecedents have taken place in 1882-83, 1932-33 and 1957-58. revkin traces the polar year project back to the inspiration of the austrian karl weyprecht. upon returning from an arctic expedition in 1874, the explorer and scientist was determined to persuade the scientifi c institutions of many nations that it was crucial to coordinate meteorological and geophysical research and to share the resulting data. weyprecht’s efforts bore fruit, though it was posthumous: he died the year before the fi rst polar year. fourteen stations ringing the arctic were established by 11 countries (norway, sweden, finland, austria, netherlands, france, germany, uk, russia, canada, us). revkin observes that the fi rst polar year marked a major change in the culture of science, which became more open, collaborative and self-critical. this book is written with the american reader in mind. for example, the arctic ocean near the north pole is described as “two miles deep— deep enough that ten empire state buildings could be stacked beneath us” (p. 11). that the book tilts decidedly toward a youthful american readership is appropriate. the american association for the advancement of science (1990) has made the point that most schoolchildren in the us are not science literate. it behooves the generation of americans about to come of age to develop a basic understanding of the causes, signs and potential impacts of climate change, as well as to improve their knowledge of other major environ188 book reviews mental problems confronting us, such as natural habitat destruction and loss of biodiversity. the scientists who are spotlighted in the north pole was here are perhaps among the fi rst people to discern the magnitude of human impacts on the natural world; our children may be among the fi rst to have to cope with these changes during their lifetimes. revkin entitled his book after a sign erected by a scientist at the north pole observatory. the joke plays on the fact that the ice supporting the temporary science camp is in constant motion. less amusing are computer simulations according to which the ice on the surface of the arctic ocean may be gone by the end of this century. as is well known in the scientifi c community, this would have radical consequences for the world. let us hope that the north pole was here— a lively paean to polar scientists—is the kind of book that engages young minds in the arctic and in science itself. reference american association for the advancement of science 1990: science for all americans. new york: oxford university press. accessed on the internet at www.project2061.org/ publications/sfaa/online/sfaatoc.htm. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <feff004f007000740069006f006e007300200070006f0075007200200063007200e900650072002000640065007300200064006f00630075006d0065006e00740073002000500044004600200064006f007400e900730020006400270075006e00650020007200e90073006f006c007500740069006f006e002000e9006c0065007600e9006500200070006f0075007200200075006e00650020007100750061006c0069007400e90020006400270069006d007000720065007300730069006f006e00200070007200e9007000720065007300730065002e0020005500740069006c006900730065007a0020004100630072006f0062006100740020006f00750020005200650061006400650072002c002000760065007200730069006f006e00200035002e00300020006f007500200075006c007400e9007200690065007500720065002c00200070006f007500720020006c006500730020006f00750076007200690072002e0020004c00270069006e0063006f00720070006f0072006100740069006f006e002000640065007300200070006f006c0069006300650073002000650073007400200072006500710075006900730065002e> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <feff0041006e007600e4006e00640020006400650020006800e4007200200069006e0073007400e4006c006c006e0069006e006700610072006e00610020006e00e40072002000640075002000760069006c006c00200073006b0061007000610020005000440046002d0064006f006b0075006d0065006e00740020006d006500640020006800f6006700720065002000620069006c0064007500700070006c00f60073006e0069006e00670020006600f60072002000700072006500700072006500730073007500740073006b0072006900660074006500720020006100760020006800f600670020006b00760061006c0069007400650074002e0020005000440046002d0064006f006b0075006d0065006e00740065006e0020006b0061006e002000f600700070006e006100730020006d006500640020004100630072006f0062006100740020006f00630068002000520065006100640065007200200035002e003000200065006c006c00650072002000730065006e006100720065002e00200044006500730073006100200069006e0073007400e4006c006c006e0069006e0067006100720020006b007200e400760065007200200069006e006b006c00750064006500720069006e00670020006100760020007400650063006b0065006e0073006e006900740074002e> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice no job name food selection by barnacle geese (branta leucopsis) in an arctic pre-breeding areapor_172 404..412 eeva m. soininen,1 christiane e. hübner2 & ingibjörg s. jónsdóttir3 1 department of arctic and marine biology, university of tromsø, no-9037 tromsø, norway 2 norwegian polar institute, po box 506, no-9171 longyearbyen, norway 3 institute of biology, university of iceland, askja, sturlugata 7, is-101 reykjavik, iceland abstract detailed patterns of food selection by pre-breeding barnacle geese (branta leucopsis) were investigated in vårsolbukta, western spitsbergen, svalbard, in moss-dominated vegetation. this habitat is favoured by geese during the early arctic spring when grass abundance is low. grass is more profitable food than moss in terms of nutrient content and digestibility, and a five-fold higher proportion of grass in geese faeces compared with other vegetation indicated that geese selected grass in spite of its low availability compared with moss. as profitability may also depend on various properties that enhance searching efficiency, we studied the effects of grass tiller size, density and patchiness on goose selectivity in an experiment comparing ungrazed vegetation with vegetation where geese were allowed to feed for controlled periods of time. large (two-leaved) tillers provided more biomass than small (one-leaved) tillers. the abundance of ungrazed large tillers relative to small tillers was lower in the grazed plots than in the ungrazed control plots, indicating that the geese preferred large tillers. grass tiller density or spatial tiller distribution did not affect the degree of selectivity of geese for grass. thus, we suggest that the feeding strategy of the geese in the early arctic spring is primarily driven by the degree of tiller conspicuousness, as determined by tiller size. furthermore, we suggest that an intense time allocation to feeding and an enhanced quality of grasses compared with mosses enabled geese to profit from feeding on the scarce grasses. keywords dietary analysis; food preferences; grass tiller size; interactions; moss; plant–herbivore; stopover ecology. correspondence eeva m. soininen, department of arctic and marine biology, university of tromsø, no-9037 tromsø, norway. e-mail: eeva.soininen@ib.uit.no doi:10.1111/j.1751-8369.2010.00172.x herbivores with limited digestive capability, like geese (owen 1980), usually exhibit selective feeding behaviour in order to forage optimally (demment & van soest 1985). they compensate their ineffective digestion by choosing food items of high quality that provide the maximal intake of nitrogen and energy (black et al. 2007). however, it is not always favourable to select high-quality food items (parsons et al. 1994; thornley et al. 1994). the smaller or more cryptic a food item is, the longer is the search time (gendron & staddon 1983; spaethe et al. 2001; jones et al. 2006), which decreases the profitability of the food item. on the other hand, search efficiency, and consequently the profitability of the preferred food item, increases with density (norberg 1977; parsons et al. 1994) and aggregated distribution (wallis de vries 1996; dumont et al. 2002). in most arctic habitats, moss is an important component of the vegetation, and its biomass often exceeds the biomass of more favourable food items such as grasses (longton 1997; born & böcher 2001; van der wal et al. 2001). this difference is even more pronounced during early spring, when mosses are available immediately after snowmelt and grass growth is still limited (prop & de vries 1993). however, young grass leaves contain more nutrients and are of better digestibility than mosses (chapin et al. 1980; prop and vulink 1992; hübner 2007), and consequently are more attractive for herbivores. this results in a trade-off situation for migrating geese in the early arctic spring as they need to choose between an abundant low-quality food source and a much less abundant high-quality food source. arctic breeding geese, like the barnacle goose (branta leucopsis), use pre-breeding stopover sites at high latitudes polar research 29 2010 404–412 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd404 mailto:soininen@ib.uit.no as stepping stones between their temperate staging areas and final breeding location in the arctic (arzel et al. 2006; glahder et al. 2006; hübner 2006). the use of stopover sites potentially enables them to adjust their arrival time at breeding sites and to build up body-fat reserves between the migration flight and breeding (hübner 2006). therefore, the stopover ecology of geese is important for our understanding of their breeding success and population ecology. however, no studies have been conducted on the feeding ecology of geese at arctic spring stopover sites, and it is not understood how they accomplish reserve supplementation in these poor feeding conditions. this study aimed to describe the current vegetation characteristics of the favoured feeding habitat in an arctic pre-breeding stopover site for barnacle geese, and to determine the feeding strategy adopted by the geese. we hypothesized that the geese should select high-quality food, such as grasses, as long as this strategy is profitable, i.e., the nutritional gain exceeds the costs of obtaining the preferred food items. grass tiller properties, which may influence the profitability of selective grass feeding, include size (hassal et al. 2001; bos et al. 2005), density (van der graaf, coehoorn et al. 2006) and detectability (kristiansen et al. 2000), which includes the degree of aggregated growth (wallis de vries 1996; dumont et al. 2002). we therefore predicted that during pre-breeding in the arctic, geese (1) select for grasses and (2) prefer large tillers over small tillers. also, we predicted their selectivity for grasses to be more pronounced when (3) the grass availability, i.e., tiller density, and (4) grass patchiness increase. prediction 1 was tested by comparing the diet composition of barnacle geese with the available plant biomass. to study the effects of grass tiller size (prediction 2), density (prediction 3) and spatial aggregation (prediction 4) the consumption of grass tillers by geese feeding in experimental plots was recorded. furthermore, characteristics of the current vegetation were described. methods research area fieldwork was conducted in vårsolbukta (77°45′n, 14°24′e), on the west coast of spitsbergen, svalbard, in spring 2005. vårsolbukta is one of the few identified pre-breeding areas for geese in svalbard (mehlum 1998), and approximately one-fifth of the svalbard barnacle goose population utilizes the area as a stopover site during spring migration (hübner 2006). the first barnacle geese arrive in mid-may, and by mid-june most of the geese have left for their nesting locations (prop et al. 1984; hübner 2006, 2007). on average, individual geese spend less than four days in the area (hübner 2006, 2007). the habitat in which most geese in vårsolbukta feed consists of a wet moss-dominated vegetation type, located below a bird cliff. the main plant species in this habitat are the moss calliergon richardsonii and a variety of grasses. early in spring, the dominant grass species that emerges is dupontia fisheri. other important vascular plant species are the grass arctophila fulva and the dicot ranunculus hyperboreus, but their availability is low during the time of the goose stopover. in this study we focused on the preferred vegetation type, which will be referred to as the calliergon–dupontia habitat. diet analysis to assess the preferences of geese for different plant groups, we compared the proportion of food items in the goose diet with their proportion in the vegetation (prediction 1). faeces of individual geese (n = 25) that had been feeding in the calliergon–dupontia habitat for at least 1 hour were collected between 19 may and 3 june. the geese were observed by telescope, and their faeces were relocated with the help of a drawing and another person. the faeces were dried, and then later re-dried in the lab at 50°c for 72 h and ground with 3 mm mesh size. in order to estimate the abundance of food items in the diet, between four and six subsamples of each faeces were inspected under a microscope (40¥). epidermis fragments of three plant groups (mosses, grasses and dicots) were recorded along a grid with 2 mm steps until 50 fragments were identified. this method is a common technique applied in several diet studies in geese (e.g., prop & vulink 1992; stahl & loonen 1998; carriére 2002; markkola et al. 2003; fox & bergersen 2005; fox et al. 2009), and is regarded as a reliable method. to analyse the available food biomass for geese in the vegetation, we harvested the aboveground biomass of eight plots (10 ¥ 20 cm) on 28 may. these plots were established randomly in the calliergon–dupontia habitat prior to goose arrival, allowing the geese free access. sampling the biomass only once was adequate for estimating the available biomass of moss and grass for the period of dropping collection, as it does not change significantly during this time in the focal habitat (hübner 2007). the samples were dried in the field and divided into the same plant groups as used for the faecal analyses. a colour code and reference samples were established to distinguish live moss from dead moss, and all plant groups were then sorted to living and dead. finally, samples were re-dried at 50°c for 72 h and weighed. food selection by barnacle geesee.m. soininen et al. polar research 29 2010 404–412 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 405 feeding strategy experiment the effects of grass properties on the feeding strategy of the geese were studied in an exclosure experiment (predictions 2, 3 and 4). sixteen plots (1 ¥ 1 m) with an adjacent control plot (40 ¥ 40 cm) were established in the calliergon–dupontia habitat before the arrival of the geese. the only other herbivore in the area is the svalbard reindeer (rangifer tarandus platyrhynchus). as the plots were established shortly after the area became snow-free, the probability that reindeer were grazing on them prior to the establishment of the exclosures is negligible. both the experimental and the control plots were covered by exclosures to prevent uncontrolled grazing. to ensure similar vegetation in the control–experimental plot pairs, the proportion and distribution of grass cover (mainly dead leaves from the previous year) was determined visually. the plot pairs were placed on snow-free vegetation between 9 and 14 may. because of the limited extent of the snow-free area, and in order to be able to observe multiple plots simultaneously, the plot pairs were placed in three groups (two groups of five and one of six pairs), with the groups being spaced approximately 150–200 m apart. within the groups, the plot pairs were randomly distributed with a distance of 5–40 m between them. corners of the experimental plots were marked with small pegs, allowing the observer to draw imaginary plot boundaries. the groups of experimental plots were opened for controlled goose grazing, all plots within a group simultaneously, on 31 may, and 1 and 2 june, respectively. with the help of a telescope, the number of geese in each plot was recorded at 1-minute intervals, with the sum of all recorded geese in a plot producing an estimate of grazing time (goose min/m2). this was included as a covariate in the statistical analysis. however, because of adverse weather conditions, the moss layer was partly frozen, and standardized moss sampling was not possible. hence, the grass/moss ratio could not be calculated. the variable grazing time is accounted for by including this variable as a covariate in our analyses of grass selectivity. immediately after the grazing trials, nine and four evenly distributed cores (9.4 cm in diameter) were taken from the experimental and the ungrazed control plots, respectively. the cores contained all live aboveground material of the grasses within the circle. to measure the grass availability in terms of density, the tillers were counted in each core. the relationship between tiller density and available grass biomass was studied by using the tiller counts of control cores. grass biomass within plots was determined by pooling grass material from all cores, following the same procedure as described for the biomass analyses in the diet analysis (see above). a measure of grass tiller consumption by the geese was achieved by tiller counts of the experimental plots, recording whether the tillers were grazed or not. as microtines are absent from the area, and no larger herbivores visited the plots during the experiment, all grazed tillers were consumed by the geese. to study the effect of grass tiller size on selectivity, the ungrazed tillers in all cores were further categorized into small and large tillers. tillers with only one leaf, in most of the cases grown during the current spring (“young leaf”), were defined to be small tillers. tillers with two leaves were defined as large tillers. in addition to the young leaf they had an older leaf (“old leaf”), which in most cases had overwintered and therefore had a dead tip (<0.5 cm). none of the tillers had more than two living leaves. to study the relationship between tiller density and weight, the tiller weights for small and large tillers were estimated by measuring the weights of the two leaf types (young and old). in one randomly chosen core of each control plot, all living leaves were picked. subsequently, the dry weight of young and old leaves was measured separately, following the same procedures as for the biomass analyses. calculations and statistical methods all statistical analyses were performed using the software package r v2.7.2 (r development core team 2008). results are given as means � ses, unless otherwise stated. the sampled grass biomass and the grass tiller numbers per plot were extrapolated to total quantities per square metre prior to the analyses. tiller weights (mg/tiller) for small and large tillers were established from the leaf weights (mg/leaf). the mean weight of young leaves was used as an estimate for small tiller weight, and the sum of the mean weights of the young and old leaves was used as an estimate for the large tillers. to study the effect of tiller density (tillers/m2) and spatial distribution of tillers (the variance of tiller numbers between cores within a plot) on the total biomass of grasses (g/m2) and the weight of individual tillers, linear regression models were fitted to the data. to normalize the data, log-tranformed variables were used for this analysis. the akaike information criterion for small sample sizes (aicc; burnham & anderson 2002) was used to select the most appropriate model. proportions of food items in goose faeces and in the vegetation were compared using a multivariate analysis of variance (manova, with pillai trace). as the food selection by barnacle geese e.m. soininen et al. polar research 29 2010 404–412 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd406 percentage of one food item was dependent on the percentage of the other food items in the sample, the data were log-ratio transformed to achieve linear independency (aebischer et al. 1993). to avoid zero values in the data, 0.01 was added to all values prior to the transformation. this value was chosen because it was an order of magnitude smaller than the smallest values of the data set, as recommended by aebischer et al. (1993). to study grass tiller size preference, the difference in the small tillers/large tillers ratio between control and experimental plots was tested with a paired student’s t-test. the grass consumption rate was measured as the proportion of grazed tillers to all tillers. an aicc selected binomial logistic regression was used to evaluate the effects of grass tiller density and spatial distribution (within-plot variance in density) on tiller consumption. correlations between the tiller densities (total, small and large tillers) and spatial distribution of tillers were evaluated with the pearson’s product–moment correlation. results characteristics of ungrazed vegetation moss constituted the major component of vegetation available for the geese in our study area (237.3 � 27.0 g/m2), with grasses (7.0 � 0.9 g/m2) and dicots (1.7 � 0.5 g/m2) representing only a small fraction. in the ungrazed control plots, the total tiller density was 3880 � 450 tillers/m2. the within-plot variance of tiller numbers per core was 105.6 � 31.0 (range: 8–483). thus, the spatial distribution within plots showed a wide range of different degrees of patchiness. the density and variance did not, however, explain the difference of total grass biomass between these plots (10.0 � 1.8 g/m2), which was best explained by a null model (linear regression, coefficient = 2.1; 95% confidence interval, ci = 1.7– 2.5; table 1). young leaves weighed on average 0.8 � 0.1 mg, whereas old leaves were significantly heavier (1.3 � 0.8 mg; paired student’s t-test, difference = 0.5 mg; 95% ci = 0.2–0.8). the biomass of large tillers (2.1 � 0.2 mg) was therefore on average 2.8 times the biomass of small tillers (paired student’s t-test, difference = 1.3 mg; 95% ci = 0.9–1.7). the majority of tillers were small, their density being 2920 � 350 tillers/m2, whereas the density of large tillers was 710 � 107 tillers/m2. the weight of large tillers was best explained by tiller density alone (tillers/m2) (linear regression, pearson correlation coefficient, rp = -0.6; coefficient = -0.6; 95% ci = -1.0 to -0.2), with the tiller weight decreasing with increasing density (fig. 1; table 1). the same was true for small tillers, even if the decrease was weaker and more uncertain (linear regression, rp = -0.5; coefficient = -0.4; 95% ci = -0.9 to 0.003) (fig. 1; table 1). this indicates that the most profitable tillers, in terms of size, are found where tiller densities are relatively low. selection between plant groups mosses formed the main food item group in the diet of the geese (table 2). however, the proportion of grass in the goose faeces was almost five times higher than in the table 1 model selection (linear regression) for total grass biomass, weight of large tillers (= wlarge) and small tillers (= wsmall) in ungrazed calliergon– dupontia vegetation in vårsolbukta, svalbard, spring 2005. predictor variables: density = log (tillers/m2); distribution = log (variance of tillers/core). variables included in the models are indicated with a “¥”. the models are ranked according to the corrected akaike’s information criterion (aicc). response variable density distribution npa aiccb daiccc awd log biomass g/m2 0 33.92 0 0.45 ¥ 1 34.48 0.55 0.34 ¥ 1 36.33 2.41 0.13 ¥ ¥ 2 37.65 3.73 0.07 log wlarge (mg) ¥ 1 13.07 0 0.76 ¥ ¥ 2 16.25 3.18 0.16 0 18.28 0.07 0.06 ¥ 1 19.88 6.82 0.03 log wsmall (mg) ¥ 1 15.18 0 0.55 0 17.04 1.85 0.22 ¥ ¥ 2 18.23 3.04 0.12 ¥ 1 18.40 3.22 0.11 a number of parameters in the model. b corrected akaike’s information criterion. c difference in aicc between the present model and the best model. d akaike weight. food selection by barnacle geesee.m. soininen et al. polar research 29 2010 404–412 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 407 vegetation, indicating that the geese selected for grasses (manova, f1,31 = 4.6, p = 0.02; table 2). grass tiller grazing geese grazed on average 16 � 0.02% of tillers in the experimental plots. the ratio of ungrazed small to ungrazed large tillers was significantly higher in the experimental plots (8.6 � 1.3) than in the control plots (5.2 � 0.9, paired student’s t-test with log-transformed data; difference = 0.5; 95% ci = 0.3–4.7). this lower relative density of large tillers in the grazed vegetation indicates that they were grazed more often than the small tillers. grass consumption by the geese was best explained by a null model (binomial logistic regression, intercept = -1.69, p = 0.02; table 3). removing an outlier with the lowest consumption, which originated from the plot where geese fed for the shortest period (11 min), did not change these results. thus, factors other than grass tiller density and spatial variation seem to be more important for the grazing pattern of geese. however, density and within-plot variance for the total tiller densities were strongly correlated in experimental plots (rp = 0.83, p < 0.001; for control plots rp = 0.42, p = 0.1), so the independent effects of density and degree of tiller patchiness was difficult to separate. this was also 7.0 7.5 8.0 8.5 9.0 9.5 − 1 .5 − 1 .0 − 0 .5 0 .0 0 .5 1 .0 1 .5 2 .0 log (tiller density) lo g ( til le r w e ig h t) small tillers log (tiller density) linear regression 95% ci large tillers 7.0 7.5 8.0 8.5 9.0 9.5 fig. 1 the relationship of tiller density (tillers/m2) and tiller weight (mg/tiller) for tillers with one leaf (small tillers) and two leaves (large tillers), respectively, in ungrazed vegetation in the calliergon–dupontia habitat in vårsolbukta, svalbard, spring 2005. linear regression lines and 95% confidence intervals (cis) are shown. table 2 mean percentages � ses of food items in the calliergon– dupontia habitat and in the faeces of barnacle geese during a prebreeding stopover in vårsolbukta, svalbard, spring 2005. food item habitat (n = 8) faeces (n = 25) moss 96.1 � 0.01 81.9 � 0.03 grass 3.2 � 0.01 15.7 � 0.03 dicot 0.7 � 0.00 2.4 � 0.01 food selection by barnacle geese e.m. soininen et al. polar research 29 2010 404–412 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd408 true for small tillers in control plots (rp = 0.49, p = 0.06), but not for large tillers (rp = 0.19, p = 0.49). discussion to our knowledge this is the first study to investigate grass selection patterns of geese in the high-arctic spring. in spite of the low availability of grasses in the vegetation during that period, the geese were selectively feeding on grasses (fulfilling prediction 1), even if moss formed the major part of their diet. they preferred large grass tillers above small ones (in keeping with prediction 2). the selectivity of the geese for grass was neither affected by tiller density nor patchiness (so predictions 3 and 4 were not fulfilled). thus, factors other than tiller distribution seemed to be important for the grazing pattern of the geese. selective foraging in patchy environments body condition before breeding is an important factor in determining the reproductive success of arctic breeding geese (ebbinge & spaans 1995; prop & black 1998; drent et al. 2003). feeding conditions in the arctic are poor during pre-breeding because the energy-rich food sources, such as grass leaves, are still small and scarce after the winter; whereas access to moss is only limited by snow cover (prop & de vries 1993; hübner 2007). because the digestive tract of geese is inefficient (owen 1980), the most profitable feeding strategy would be—all things being equal—to select the high-quality grass leaves and avoid moss because of its low nutrient content and digestibility (chapin et al. 1980; prop & vulink 1992; hübner 2007). however, feeding on less abundant food results in long searching times and a low food intake rate (norberg 1977; parsons et al. 1994). in this study, barnacle geese had an approximately five-fold higher proportion of grasses in their diet compared with the available vegetation. thus, it is evident that the geese used a selective feeding strategy in spite of the low availability of good-quality food items in the vegetation (3% grass of the total live aboveground plant biomass). even if the search time for grasses is likely to be longer than for moss, this does not seem to counteract their nutritional advantage. these results are in line with the study of alsos et al. (1998), who found female barnacle geese selected grass even at low availabilities (5% of vegetation cover) during incubation. a possible explanation for the selectivity of scarce food items is an enhanced nutritional difference between the available food sources. grass quality is highest early in spring and decreases over the course of the growth season (chapin et al. 1980; crawley 1983; manseau & gauthier 1993; van der graaf, stahl et al. 2006). similar changes in mosses have not been studied. during early spring, the difference in quality between vascular plants and mosses is nevertheless likely to be at its peak, presumably compensating for the low availability of grasses. manure from seabirds has been found to increase the nutrient content of vascular plants growing below bird cliffs (anderson & polis 1999; born & böcher 2001). however, a comparable increase of nitrogen content could not be shown for mosses below the bird cliff in the present study area (hübner 2007). consequently, differential responses to seabird manure between grasses and mosses may enhance the quality difference between preferred and less preferred food items even further at this study site. table 3 model selection (logistic binomial regression) for grass consumption (= grazed tillers/all tillers) by barnacle geese in the calliergon–dupontia habitat during a pre-breeding stopover in vårsolbukta, svalbard, spring 2005. predictor variables: density = log(tillers/m2); distribution = log(variance of tillers/core); time = grazing time of geese in plot (min). variables included in the models are indicated with a “¥”. the models are ranked according to the corrected akaike’s information criterion (aicc). response variable density distribution time npa aiccb daiccc awd consumption 0 7.38 0 0.52 ¥ 1 10.09 2.79 0.13 ¥ 1 10.09 2.71 0.13 ¥ 1 10.10 2.73 0.13 ¥ ¥ 2 13.28 5.91 0.03 ¥ ¥ 2 13.29 5.91 0.03 ¥ ¥ 2 13.29 5.90 0.03 ¥ ¥ ¥ 3 17.11 9.73 0.00 a number of parameters in the model. b corrected akaike’s information criterion. c difference in aicc between the present model and the best model. d akaike weight. food selection by barnacle geesee.m. soininen et al. polar research 29 2010 404–412 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 409 detecting and selecting grasses in a moss carpet geese feeding on small grass tillers have a small bite size, resulting in low intake rates (hassal et al. 2001). consequently, geese should prefer larger tillers, which is also the case in the present study. tiller size difference in this study was based on the number of leaves, and a large tiller, with both a young and an old leaf, contained more than twice the volune of biomass than a small tiller. however, newly grown young leaves contain more nutrients and less structural components than old leaves from the previous year (cargill & jefferies 1984; sedinger & raveling 1986; manseau & gauthier 1993). because of this lower quality, the additional old leaf in the large tiller probably only marginally adds to the quantity of nutrients in the tiller, in spite of the increased biomass. the difference in nutrient intake provided by small and large tillers is thus unlikely to determine their profitability alone. an alternative explanation for the preference of geese for large tillers is their augmented conspicuousness (kristiansen et al. 2000). the vegetation in the calliergon– dupontia habitat consisted of a thick moss layer interspersed with grass tillers. at the time of the goose stopover, many dead grass leaves were still attached to the tillers, and protected the living part that had barely emerged above the moss layer (mean length of leaves from 50 tillers of d. fisheri collected in the calliergon– dupontia habitat in the study area on 3 june 2003: 2.1 � 0.1 cm and 3.1 � 0.1 cm for young and old leaves, respectively). under such conditions, large tillers are likely to be easier to detect for the geese than small ones, and selecting large tillers would thus enhance the search efficiency. in order to optimize their feeding, both in relation to search time and gain of nutrients, geese may select the young nutrient-rich leaves of large conspicuous tillers. the methods used in this study did not, however, allow for quantifying the relative consumption of leaf types in large tillers. conspicuousness of food plants may also be enhanced by patchy growth. patchy resources have been found to increase the search efficiency of herbivores, and to thus favour selectivity over a range of densities and spatial scales (edwards et al. 1994; dumont et al. 2002). however, the effects of food item properties on foraging strategies are poorly understood (jones et al. 2006). if searching efficiency is a significant component of the profitability of grass tillers, geese should show a higher degree of selectivity when tillers grow more clustered, but such a pattern was not found in this study. the density of small tillers correlated with the patchiness, whereas the density of large tillers did not. consequently, the easier detectability of larger tillers may have counteracted the effect of tiller patchiness on the searching efficiency of the geese. grass tiller density did not seem to affect the degree of selectivity of the geese either. as the total tiller density and tiller patchiness were correlated, it was not possible to unravel their separate effects on tiller consumption by the geese. furthermore, both small and large tillers decreased in weight when tiller density increased. the benefit of increased tiller density was therefore partly counteracted by a reduction in biomass per tiller. this is further supported by the findings that the total grass biomass in a plot was independent of the tiller density. in summary, the geese in this study were feeding selectively on grasses in spite of the low availability. the geese preferred grasses with two leaves, which provided more biomass and were easier to detect. such enhanced conspicuousness is an important feature when preferred food items are generally small, scattered and hidden within the surrounding vegetation. furthermore, neither the overall tiller density, nor patchiness, were found to have an effect on their selectivity, which was probably because of the decreased weight and detectability of densely growing tillers. we therefore suggest that the conspicuousness of food items plays an important role in the food selection of geese during the early arctic spring. acknowledgements we thank hanna kokko, markus öst and rosie barlak for comments on an earlier version of the manuscript. we are grateful to cecilia sandström, jannik schultner and joris tinnemans for sorting some of our samples. we thank nigel gilles yoccoz and niels felsted thorsen for their help with the r statistical program, rolf a. ims and jouke prop for comments on the manuscript, and ellen kathrine thomassen for help with the language. this study was financed by the norwegian research council, the roald amundsen centre for arctic research, in tromsø, and the norwegian national committee on polar research. at the time the research reported here was carried out the authors were affiliated with the university centre in svalbard. ems was also affiliated with the department of biological and environmental sciences of the university of helsinki. references aebischer n.j., robertson p.a. & kenward r.e. 1993. compositional analysis of habitat use from animal radio-tracking data. ecology 74, 1313–1325. alsos i.g., elvebakk a. & gabrielsen g.w. 1998. vegetation exploitation by barnacle geese branta leucopsis during incubation on svalbard. polar research 17, 1–14. food selection by barnacle geese e.m. soininen et al. polar research 29 2010 404–412 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd410 anderson w.b. & polis g.a. 1999. nutrient fluxes from water to land: seabirds affect plant nutrient status on gulf of california islands. oecologia 118, 324–332. arzel c., elmberg j. & guillemain m. 2006. ecology of spring-migrating anatidae: a review. journal of ornithology 147, 167–184. black j.m., prop j. & larsson k. 2007. wild goose dilemmas. groeningen: branta. born e.w. & böcher j. 2001. the ecology of greenland. nuuk: ministry of environment and natural resources. bos d., drent r.h., rubinigg m. & stahl j. 2005. the relative importance of food biomass and quality for patch and habitat choice in brent geese branta bernicla. ardea 93, 5–16. burnham k.p. & anderson d.r. 2002. model selection and multi-model inference: a practical information–theoretic approach. 2nd edn. new york: springer. carriére s. 2002. photographic key for the microhistological identication of some arctic vascular plants. arctic 55, 247–268. cargill s.m. & jefferies r.l. 1984. the effects of grazing by lesser snow geese on the vegetation of a sub-arctic salt marsh. journal of applied ecology 21, 669–686. chapin f.s. iii, johnson d.a. & mckendrick j.d. 1980. seasonal movement of nutrients in plants of differing growth forms in an alaskan tundra ecosystem, implications for herbivory. journal of ecology 68, 189–209. crawley m.j. 1983. herbivory: the dynamics of animal–plant interactions. oxford: blackwell. demment m.v. & van soest p.j. 1985. a nutritional explanation for body size patterns of ruminant and nonruminant herbivores. american naturalist 125, 641–672. drent r.h., both d., green m., madsen j. & piersma t. 2003. pay-offs and penalties of competing migratory schedules. oikos 103, 274–292. dumont b., carriére p. & d’hour p. 2002. foraging in patchy grasslands: diet selection by sheep and cattle is affected by the abundance and spatial distribution of preferred species. animal research 51, 367–381. ebbinge b.s. & spaans b. 1995. the importance of body reserves accumulated in spring staging areas in the temperate zone for breeding in dark-bellied brent geese branta b. bernicla in the high arctic. journal of avian biology 26, 105–113. edwards g.r., newman j.a., parsons a.j. & krebs j.r. 1994. effects of the scale and spatial distribution of the food resource and animal state on diet selection: an example with sheep. journal of animal ecology 63, 816–826. fox a.d. & bergersen l. 2005. lack of competition between barnacle geese branta leucopsis and pink-footed geese anser brachyrhynchus during the pre-breeding period in svalbard. journal of avian biology 36, 173–178. fox a.d., eide n.e., bergesen e. & madsen j. 2009. resource partitioning in sympatric arctic-breeding geese: summer habitat use, spatial and dietary overlap of barnacle and pink-footed geese in svalbard. ibis 151, 122–133. gendron r.p. & staddon j.e.r. 1983. searching for cryptic prey: the effect of search rate. american naturalist 121, 172–186. glahder c.m., fox a.d., hübner c.e., madsen j. & tombre i.m. 2006. pre-nesting site use of satellite transmitter tagged svalbard pink-footed geese. ardea 94, 679–690. hassal m., riddington r. & helden a. 2001. foraging behavior of brent geese, branta b. bernicla, on grasslands: effects of sward length and nitrogen content. oecologia 127, 97–104. hübner c.e. 2006. the importance of pre-breeding sites in the arctic barnacle goose branta leucopsis. ardea 94, 701–713. hübner c.e. 2007. spring stopover in the arctic: implications for migrating geese and their food plants. phd thesis, university centre in svalbard. jones k.a., krebs j.r. & whittingham m.j. 2006. interaction between seed crypsis and habitat structure influence patch choice in a granivorous bird, the chaffinch fringilla coelebs. journal of avian biology 37, 413–418. kristiansen j.n., fox a.d. & nachman g. 2000. does size matter? maximizing nutrient and biomass intake by shoot selection amongst herbivorous geese. ardea 88, 119–125. longton r.e. 1997. the role of bryophytes and lichens in polar ecosystems. in s.j. woodin & m.e. marquiss (eds.): ecology of arctic environments. pp. 69–96. blackwell, oxford. manseau m. & gauthier g. 1993. interactions between greater snow geese and their rearing habitat. ecology 74, 2045–2055. markkola j., niemelä m. & rytkönen s. 2003. diet selection of lesser white-fronted geese anser erythropus at a spring staging area. ecography 26, 705–714. mehlum f. 1998. areas in svalbard important for geese during the pre-breeding, breeding and post-breeding periods. in f. mehlum et al. (eds.): proceedings of the svalbard goose symposium, oslo, norway, 23–26 september 1997. norsk polarinstitutt skrifter 200. pp. 41–55. tromsø: norwegian polar institute. norberg r.a. 1977. an ecological theory on foraging time and energetics and choice of optimal food-searching method. journal of animal ecology 46, 511–529. owen m. 1980. wild geese of the world. london: bt batsford. parsons a.j., thornley j.h.m., newman j. & penning d.p. 1994. a mechanistic model of some physical determinants of intake rate and diet selection in a two-species temperate grassland sward. functional ecology 8, 187–204. prop j. & black m.j. 1998. food intake, body reserves and reproductive success of barnacle geese branta leucopsis staging in different habitats. in f. mehlum et al. (eds.): proceedings of the svalbard goose symposium, oslo, norway, 23–26 september 1997. norsk polarinstitutt skrifter 200. pp. 175–193. tromsø: norwegian polar institute. prop j. & de vries j. 1993. impact of snow and food conditions on the reproductive performance of barnacle geese branta leucopsis. ornis scandinavica 24, 110–121. prop j., van eerden m.r. & drent r.h. 1984. reproductive success of the barnacle goose branta leucopsis in relation to food selection by barnacle geesee.m. soininen et al. polar research 29 2010 404–412 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 411 food exploitation on the breeding grounds, western spitsbergen. in f. mehlum & m. ogilvie (eds.): current research on artic geese. proceedings of a symposium at voksenåsen, oslo, 24–26 october 1983. norsk polarinstitutt skrifter 181. pp. 87–117. oslo: norwegian polar institute. prop j. & vulink t. 1992. digestion by barnacle geese in the annual cycle—the interplay between retention time and food quality. functional ecology 6, 180–189. r development core team 2008. a language and environment for statistical computing. vienna: r foundation for statistical computing. sedinger j.s. & raveling d.g. 1986. timing of nesting by canada geese in relation to the phenology and availability of their food plants. journal of animal ecology 55, 1083–1102. spaethe j., tautz j. & chittka l. 2001. visual constraints in foraging bumblebees: flower size and color affect search time and flight behaviour. proceedings of the national academy of sciences of the united states of america 98, 3898–3903. stahl j. & loonen m.j.j.e. 1998. effects of predation risk on site selection of barnacle geese during brood-rearing. in f. mehlum et al. (eds.): proceedings of the svalbard goose symposium, oslo, norway, 23–26 september 1997. norsk polarinstitutt skrifter 200. pp. 67–79. tromsø: norwegian polar institute. thornley j.h.m., parsons a.j., newman j. & penning p.d. 1994. a cost–benefit model of grazing intake and diet selection in a two-species temperate grassland sward. functional ecology 8, 5–16. van der graaf a.j., coehoorn p. & stahl j. 2006. sward height and bite size affect the functional response of barnacle geese branta leucopsis. journal of ornithology 147, 479–484. van der graaf a.j., stahl j., klimkowska a., bakker j.p. & drent r.h. 2006. surfing on a green wave—how plant growth drives spring migration in the barnacle goose. ardea 94, 567–577. van der wal r., van lieshout s.m.j. & loonen m.j.j.e. 2001. herbivore impact on moss depth, soil temperature and arctic plant growth. polar biology 24, 29–32. wallis de vries m.f. 1996. effects of resource distribution patterns on ungulate foraging behaviour: a modeling approach. forest ecology and management 88, 167–177. food selection by barnacle geese e.m. soininen et al. polar research 29 2010 404–412 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd412 doi:10.3402/polar.v33.21630 r e s e a r c h / r e v i e w a r t i c l e instrumentation and handling effects on antarctic fur seals (arctocephalus gazella) marie-anne blanchet,1 christian lydersen,1 martin biuw,1 p.j. nico de bruyn,2 greg hofmeyr,2 bjørn a. krafft 1,3 & kit m. kovacs 1 1 norwegian polar institute, fram centre, no-9296 tromsø, norway 2 department of zoology and entomology, mammal research institute, university of pretoria, private bag x20, hatfield 0028, pretoria, south africa 3 institute of marine research, no-5870 bergen, norway keywords bioenergetics; biologging; instrument effects; srdls; tdrs; vhfs. correspondence kit m. kovacs, norwegian polar institute, fram centre, no-9296 tromsø, norway. e-mail: kit.kovacs@npolar.no abstract the use of biologging instruments has greatly improved our understanding of the behaviour, physiology and ecology of free-ranging marine mammals. however, handling wild animals and attaching instruments to streamlined bodies can cause stress and potentially influence behaviour and swimming/ diving energetics. the goals of this study, undertaken on bouvetøya, were (1) to determine if the first trip to sea after instrumentation is representative of subsequent trips in lactating antarctic fur seals, to explore potential handling effects and assess possible biases in having multiple short-duration deployments (inflating n, using a limited number of tags) and (2) to evaluate potential effects of two different instrument combinations (smru satellite data relay loggers and very high frequency radio transmitters versus wildlife computers time�depth recorders and very high frequency radio transmitters) on trip durations, dive parameters, female body condition and pup growth. handling did not appear to have any effects on the parameters studied; data from the first and second trips did not differ significantly. this implies that multiple short-term deployments are unlikely to result in biased data in this species. instrument type did have measurable effects; time-at-sea was greater and pup growth was lower for pairs in which mothers carried bulkier instruments. this suggests that instrument streamlining is important to avoid negative impacts and that bulkier equipment should be deployed on lactating females with caution and only for short periods. the study highlights that instrument effects should be taken into account when comparing data from experiments collected using different equipment packages. data on foraging patterns are crucial for understanding the ecology of animals and how sensitive they might be to environmental changes (wilson et al. 1986). however, for marine mammals direct observations are not often feasible in the wild since they feed at sea, often beneath the surface and are only on shore for short periods, if they come ashore at all (mcmahon et al. 2008). instrumentation of free-ranging marine mammals has therefore become a vital means of accruing information on their behaviour in their natural environments (e.g., boyd et al. 2004; trathan & croxall 2004; wilson & mcmahon 2006; hooker et al. 2007; ropert-coudert, wilson et al. 2007). animal-borne instruments have become increasingly sophisticated over the past few decades (heaslip & hooker 2008; mccafferty et al. 2007), enabling the collection of a wide diversity of behavioural and physiological data, as well as environmental data (e.g., biuw et al. 2010). for example, heart beats, feeding events, diving parameters, water temperature, light levels and salinity are now possible to record with animal-borne instruments, which also permit the spatial tracking of animals (see rutz & hays 2009). (page number not for citation purpose) polar research 2014. # 2014 m.-a. blanchet et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 21630, http://dx.doi.org/10.3402/polar.v33.21630 http://www.polarresearch.net/index.php/polar/article/view/21630 http://dx.doi.org/10.3402/polar.v33.21630 biologging/biotelemetry instruments can now store or relay vast data sets. but, acquiring samples from a large enough pool of individuals to be representative of a population remains a challenge, mainly due to the high economic cost of the instruments (trathan & croxall 2004). one way to achieve a larger sample size of individuals with a limited number of instruments is to reduce the deployment time per animal and redeploy the same tags on several animals in succession during a field season (agnew 2004), thus recording only one or a few foraging trips per animal, but achieving a higher n (e.g., beauplet et al. 2004). however, capturing, handling and restraining wild animals can cause significant stress that can potentially influence their post-release behaviour (weimerskirch et al. 2002; hawkins 2004; wilson & mcmahon 2006). the immediate, post-release period would be the most likely time in which the animal’s behaviour might be abnormal as it becomes accustomed to the instrument and recovers from the capture experience. studying only this period might introduce significant bias into behavioural/energetic analyses. in addition, fitting an instrument onto the streamlined body of a swimming/diving animal could potentially cause discomfort and create drag that could increase the energetic costs of locomotion, introducing bias to all collected data. it is therefore crucial to ensure that the results and conclusions inferred from biologging and telemetry data are valid by assessing the potential effects of instruments on animal behaviour, energetics and fitness whenever possible (wilson et al. 1986; croll et al. 1991; walker & boveng 1995; mcmahon et al. 2008; walker et al. 2012). previous studies have shown that instruments placed on marine mammals can cause changes in swim speed, dive frequency or attendance duration (see boyd et al. 1991; boyd et al. 1997; walker & boveng 1995; francis et al. 1998; mccafferty et al. 1998; littnan et al. 2004; mccafferty et al. 2007; ropert-coudert, knott et al. 2007). however, considerable progress in technology and design has been made since the early days of biologging with regards to miniaturization and streamlining, which has helped reduce instrument effects on subject animals (mccafferty et al. 2007). despite this, possible effects of instruments should not be ignored from an animal welfare or a scientific perspective (see field et al. 2012). the latter is especially important when comparing data series that have been collected using a variety of different instruments (trathan & croxall 2004). antarctic fur seals (arctocephalus gazella; afs) haul out on a number of isolated islands, including bouvetøya. adult females give birth annually during the austral summer (bonner 1968). during lactation they undertake a regular cycle of four�five days foraging at sea alternating with two�three days attending their dependant pup ashore (costa et al. 1989; boyd 1999; guinet et al. 2000), until their pups are weaned at a mean age of 114 days (kovacs & lavigne 1992). the at-sea behaviour of lactating adult females from various populations has been the subject of numerous studies employing a variety of attached devices (e.g., staniland et al. 2007; biuw et al. 2009; casper et al. 2010; goldsworthy et al. 2010; gastebois et al. 2011). however, few studies have specifically considered the effects of disturbance due to handling or instrument deployment on the characteristics of the foraging behaviour that they are attempting to study. the goals of this study were (1) to determine if the first trip to sea after instrumentation is representative of subsequent trips in lactating afs tagged at bouvetøya and (2) to evaluate potential effects of different instrument types on trip durations, dive parameters, female body condition and pup growth. materials and methods this study took place at nyrøysa (54.418 s, 03.298 e) on the west coast of bouvetøya, south atlantic, during three austral summer seasons (2000/01, 2001/02, 2007/08). a total of 46 lactating afs were instrumented with various combinations of biotelemetry gear during the study (table 1). females with newborn pups were selected, assuming that the presence of an umbilicus/ placenta indicated that mothers were still in their perinatal period, that is, still ashore after giving birth, before departing for their first trip to sea. the mothers were manually restrained using a large cone-shaped hoop net (2.2 m long �1 m in diameter) attached to an aluminium frame and handle (see david et al. 1990 for further details). body mass was measured to the nearest table 1 summary of instrument deployments on lactating antarctic fur seals at bouvetøya during three austral summers (2000/01, 2001/02, 2007/08): satellite relay data loggers (srdls), time�depth recorders (tdrs), platform transmitter terminals (ptts) and very high frequency radio transmitters (vhfs). season animals captured (n) srdl (n) tdr�vhf (n) tdr�ptt �vhf (n) 2000/01 12 3 9 � 2001/02 10 3 7 � 2007/08 20 � � 20 instrumentation and handling effects on antarctic fur seals m.-a. blanchet et al. 2 (page number not for citation purpose) citation: polar research 2014, 33, 21630, http://dx.doi.org/10.3402/polar.v33.21630 http://www.polarresearch.net/index.php/polar/article/view/21630 http://dx.doi.org/10.3402/polar.v33.21630 0.1 kg using a 100 kg salter scale prior to instrument attachment and upon recovery (table 2). all instruments were glued to the fur of the adult females in the middorsal region with two-component industrial-grade epoxy (huntsman aw2101/hw2951, intertronics, kidlington, oxfordshire, uk, or 5-cure, industrial formulators inc., port coquitlam, bc, canada). during their mothers’ instrument deployment period the pups were also weighed several times by suspending them briefly in a canvas bag attached to a mechanical spring; the first weight was taken when the mothers’ instrument(s) were deployed. different combinations of instruments were used in the different seasons (table 1); all had at least one instrument with a protruding antenna. during 2000/01 and 2001/02, a total of six satellite relay data loggers (srdls; sea mammal research unit, st. andrews, uk) and 20 mk6 time�depth recorders (tdrs; wildlife computers, redmond, wa, usa) in combination with very high frequency transmitters (vhfs; model 5955, advanced telemetry systems, isanti, mn, usa) were deployed. the tdrs were removed after five�six weeks of deployment, prior to the expedition’s departure from the island, while the srdls were left on the animals to table 2 deployment and recovery statistics for antarctic fur seals equipped with satellite relay data loggers (srdls), time�depth recorders (tdrs) and very high frequency radio transmitters (vhfs) at bouvetøya in 2000/01 and 2001/02. female weight (kg) pup weight (kg) date deployed seal id no. duration (d) at deployment at recapture weight diff. pup sex at deployment at recapture srdl n �6 2000 dec 17 bv1-1553-00 24 35 32 �3 f 6.55 8.5 2000 dec 17 bv1-22497-00 na a 36 na a na a f 5.1 7.1 2000 dec 17 bv1-2848-00 64 39 35 �4 f 5.25 7.4 2001 dec 14 bv2-28489-01 45 42 33 �9 m 4.8 8.7 2001 dec 14 bv2-28490-01 37 43 37 �6 m 5.65 9.6 2001 dec 14 bv2-28491-01 48 53 39 �14 f 4.6 9.9 means9sd 43.6914.7 41.396.5 35.292.8 �7.294.4 5.390.7 8.591.3 tdr n �16 2000 dec 18 bv1-003-00 50 41 42 �1 m 5.5 9.8 2000 dec 18 bv1-024-00 43 27 29.5 2.5 m 4.75 9.5 2000 dec 19 bv1-033-00 45 32 33 �1 m 5.2 11 2000 dec 20 bv1-052-00 43 29 28 �1 f 5.1 7.9 2000 dec 20 bv1-073-00 41 34 34 0 f 4.3 6.8 2000 dec 21 bv1-092-00 40 37 34 �3 f 5.1 11 2000 dec 21 bv1-105-00 42 36 30 �6 f 4.3 9 2001 dec 15 bv2-468-01 39 47 45 �2 m 6.1 13.2 2001 dec 15 bv2-479-01 39 38 31 �7 f 4.7 9 2001 dec 15 bv2-457-01 39 48 38 �10 f 5.3 10.2 2001 dec 15 bv2-587-01 40 34 32 �2 m 5.3 11.4 2001 dec 15 bv2-966-01 39 36 38 �2 f 4.8 8.7 2001 dec 16 bv2-438-01 38 43 32.5 �10.5 f 4 8.2 2001 dec 16 bv2-550-01 43 42 35 �7 f 4.8 8.8 2001 dec 17 bv2-758-01 38 43 42 �1 f 6 10 2001 dec 17 bv2-999-01 41 44 34 �10 f 4.8 8.7 means9sd 41.293.1 38.296.1 34.894.3 �3.394.5 5.090.6 9.691.5 vhf n �11 2001 dec 18 b-162 38 37 33 �4 f 4.6 8 2001 dec 18 b-176 38 43 37 �6 f 3.8 8 2001 dec 19 b-178 38 38 32 �6 m 5.1 9.7 2001 dec 19 b-182 38 41 naa naa m 5.6 8.6 2001 dec 19 b-184 38 27 28 1 f 3.9 6.9 2001 dec 19 b-186 38 30 29 �1 f 4.1 5.8 2001 dec 19 b-188 37 33 29 �4 f 5.1 8.2 2001 dec 21 b-192 36 30 31 1 f 5.3 7.6 2001 dec 21 b-196 35 35 28 �7 f 4.5 7.1 2001 dec 21 b-211 40 34 36 2 m 5.3 6.5 2001 dec 21 no-241 36 49 44 �5 f 5.1 7.9 means9sd 37.493.4 35.696.5 32.7953.1 �2.993.4 4.890.6 7.791.1 a data not available. m.-a. blanchet et al. instrumentation and handling effects on antarctic fur seals citation: polar research 2014, 33, 21630, http://dx.doi.org/10.3402/polar.v33.21630 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21630 http://dx.doi.org/10.3402/polar.v33.21630 fall off naturally during the annual moult. the srdl data used in the present study covered only the first five�six weeks of lactation, during which both srdl and tdr data were collected. instrument dimensions and weights are summarized in table 3. the srdls sampled depth every 4 s while diving and the on-board processor was set to define the start of a dive to occur when the tag was wet and below 5 m for 8 s. a dive ended when the tag either returned to within 5 m of the surface or became dry. the mk6 tdrs sampled depth every 10 s while the tag was wet and had a depth resolution of 2 m. raw data files obtained from the mk6 tdrs were extracted using purpose-built software provided by the manufacturer (dive analysis, zero offset correction, minimummaximum-mean, wildlife computers). any excursion from the surface to a depth ]5 m for at least 8 s was considered a dive, matching the settings of the srdls. during 2007/08, three instruments were simultaneously deployed on each of 20 adult female afs: (1) a 0.5 w sirtrack kiwisat 101 platform terminal transmitter (ptt; sirtrack inc., havelock north, new zealand); (2) a tdr (mk9 wildlife computers); and (3) a sirtrack vhf to facilitate recapture. all three instruments were glued to the fur along the main axis of the animal in the middorsal region (behind the scapulae), with the tdr and the vhf in front of the ptt (see table 3 for details on the instruments’ characteristics). the tdrs were programmed to record depth at a resolution of 0.5 m, and light level every second, both when wet and dry in order to record attendance patterns precisely. any excursion from the surface to a depth ]5 m for at least 8 s was defined as a dive to match the definition of the instruments from the two preceding study periods. start and end times of trips were defined based on dive and conductivity switch records from the tdrs, or based upon distance from the island for animals with srdls and ptts. to obtain the best possible representation of the real path followed by the animals, a speed�distance�angle filter (see freitas et al. 2008) was applied to the tracks recorded by the srdls and ptts. all statistical analyses were conducted using r, version 2.12.1 (r development core team 2009). all distances from the island refer to great circle distances and the maximum corresponds to the most distant point reached within a trip. when statistical models were used, model fitting was based on the examination of the residuals and kolmogorov�smirnov tests were used to assess whether or not data were normally distributed. handling effect/instrumentation effect first and second trips were compared from a total of 84 trips, performed by 42 animals, across three summer seasons (table 4). four instruments malfunctioned and were not included in the analysis. only the first two trips were compared in order to minimize possible confounding effects of date\lactation stage. each trip parameter (trip duration, maximum distance reached from the island, total distance swam, mean dive duration, mean dive depth) was compared between trip 1 and trip 2 using linear mixed effect models (lmes). these models were fitted with the trip number, departure date and year as fixed effects and animal identification number (id) as a random effect. the mixed-effect structure accounts for correlations in the data arising from individual animal effects; in this case trips 1 and 2 are performed by the same animal and hence not independent. instrument effect only records from 2000/01 and 2001/02 were useful for exploring potential impacts of different instrument types on trip parameters because in 2007/08 all animals bore the same gear combination resulting in a confounding effect between ‘‘year’’ and ‘‘instrument type.’’ in this latter season, deployment periods were also much reduced compared to the first field seasons. for the two years with comparable data, attendance patterns (trip duration and haul-out duration), mean dive duration table 3 summary of the characteristics of instruments deployed on bouvetøya during three austral summers: satellite relay data loggers (srdls), time�depth recorders (tdrs), platform transmitter terminals (ptts) and very high frequency radio transmitters (vhfs). instrument length width height weight (air) weight (water) % body mass a % frontal area b vhfs c 82 20 20 36 20 0.06 1.0 vhfs d 45 30 24 70 15 0.12 1.2 tdrs (mk6) 65 35 15 53 18 0.13 1 tdrs (mk9) 67 17 17 30 12 0.07 0.6 srdls 105 70 35 400 135 1 4.5 ptts 156 62 19 275 100 0.7 1.9 a assuming an average body mass for an adult female antarctic fur seal of 40 kg. b assuming an average frontal area for an adult female antarctic fur seal of 490 cm 2 . c vhfs deployed during the 2000/01 and 2001/02 seasons. d vhfs deployed during the 2007/08 season. instrumentation and handling effects on antarctic fur seals m.-a. blanchet et al. 4 (page number not for citation purpose) citation: polar research 2014, 33, 21630, http://dx.doi.org/10.3402/polar.v33.21630 http://www.polarresearch.net/index.php/polar/article/view/21630 http://dx.doi.org/10.3402/polar.v33.21630 and average depth per trip were compared using lmes. these models were fitted with tag type, trip departure dates and year as fixed effects and animal id as a random effect, to take into account individual variability and the different number of trips performed by each individual. due to transmission bandwidth constraints in the argos system, the dive records collected by the srdls were compressed and not every recorded dive was transmitted (see fedak et al. 2001). transmitted dives are randomly selected from a buffer containing 600 dives, and about 30% of the total number of dives was transmitted during these deployments (see biuw et al. 2009 for details). in order to assess potential biases due to the different sampling regimes between the srdls and the tdrs, both the entire tdr records and a random sampling of 30% of the same records were used in the analysis. the effect of the tags on the female’s body condition was assessed by comparing the mass change per day between deployment and recovery of the instruments using an anova. the pup growth rates were compared using lme. pups of instrumented mothers were included in the analysis if there were at least two weight measurements taken during the tagging period of their mothers. the models were fitted with pup age, year and instrument type borne by the mother as fixed effects and animal id as a random effect, to take into account the lack of independence of repeated measurement of individual pups. mass measurements from mothers (and their pups) carrying srdls or tdrs were used in this part of the analyses. results summary statistics for trip parameters for trips 1 and 2 are presented in table 4. none of the parameters were significantly different for the two trips (table 5). date was not a significant variable in any of the models, but year influenced the mean dive duration and the mean dive depth. both variables were significantly greater in 2007/ 08 compared to the two first seasons. a total of 189 trips and 168 haulout periods were used to compare the attendance patterns and the trip parameters between the two instrument groups (table 6). a summary of the lmes used to explore these data is presented in table 7. the mean trip duration was significantly greater for srdl animals (meansrdl � 103.9933.7 h) compared to tdr instrumented females (meantdr �65.4921.5 h). instrument type and date were significant variables in the lme model, while year was not significant. the mean haulout duration was not significantly different between the two instrument groups (srdl animals 45.3910.9 h; tdr animals 37.7917.0 h), nor were any of the other variables tested in the model. dive duration and dive depth were only influenced by date and year but not by the instrument type carried by the female. the data sub-sampling table 4 summary statistics for trip 1 and trip 2 for antarctic fur seal females at bouvetøya equipped with satellite relay data loggers (srdls) and very high frequency radio transmitters (vhfs; 2000�02), time�depth recorders (tdrs) and vhfs (2000�02), and platform transmitter terminals (ptts) and tdrs and vhfs (2007/08). maximum distance and total distance swam could only be calculated for animals carrying srdls or ptts. trip 1 trip 2 n a mean sd mean sd duration (h) 42 60.8 23.9 58.6 32.3 max. distance (km) 24 56.8 31.2 59.1 37.9 total distance (km) 24 175.3 87.9 186.1 129.1 mean dive duration (s) 42 59.1 13.5 57.42 13.6 mean dive depth (m) 42 20.4 7.7 20.5 8.3 a number of animals used in the analysis. table 5 summary of the linear models used to compare the trip parameters between trip 1 and trip 2. maximum distance refers to the maximum distance from the island reached within a trip and total distance refers to the total distance swam during a trip. for maximum distance and total distance only, animals fitted with satellite relay data loggers (srdls) or platform transmitter terminals (ptts) were used in the analysis. trip parameter model term f value df pa trip duration trip number 0.17 40 0.68 date 0.01 40 0.90 year 1.33 39 0.27 maximum distanceb trip number 0.20 22 0.65 date 0.21 22 0.64 year 0.61 21 0.55 total distance trip number 0.18 22 0.67 date 0.01 22 0.95 year 0.45 21 0.65 dive durationb trip number 0.46 39 0.50 date 0.37 39 0.37 year 5.70 38 b0.01 dive depth b trip number 0.02 39 0.90 date 0.02 39 0.87 year 4.77 38 b0.05 a high significance levels in boldface. b parameters log-transformed. m.-a. blanchet et al. instrumentation and handling effects on antarctic fur seals citation: polar research 2014, 33, 21630, http://dx.doi.org/10.3402/polar.v33.21630 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21630 http://dx.doi.org/10.3402/polar.v33.21630 performed by the srdls did not affect the results, as the estimates and the p-values were similar between the model using the complete tdr data set or a matching random 30% sample of the tdrs data records, simulating sampling similar to the srdl (table 7). the females instrumented with srdls had similar masses to those instrumented with tdrs when capture and instrument deployments took place (meansrdl�42.29 6.6 kg; meantdr �37.896.4 kg; anova f1,23 �2.02; p �0.17). the percentage mass loss per day (meansrdl � �0.3990.15%; meantdr � �0.1890.28%; anova f1,23 �2.59; p �0.12) and the total mass loss over the period of instrumentation (meansrdl � �7.294.4 kg; meantdr � �2.894.4 kg; anova f1,23; p �0.055) were not statistically different for the two groups, although the mean values for the srdl group were more than twice that of the tdr group for both parameters. pup start masses were not significantly different between the two instrument groups (meansrdl �5.39 0.7 kg; meantdr �5.090.5 kg; anova f1,20 �1.19; p � 0.28). over the study period, pup growth was close to linear in each treatment group (fig. 1). the simplest lme model fitted to explore pup growth rate used pup age, instrument type borne by the mother and the interaction between age and instrument. pup sex and the interaction between age and pup sex were tested but there was no significant differences (table 7). however, pups with srdl-instrumented mothers grew significantly slower than those with tdr-instrumented mothers (growth ratesrdl �0.07890.011 kg day �1 ; growth ratetdr � 0.10490.025 kg day �1 ). discussion there were no detectable differences in the recorded trip parameters (trip duration, maximum distance, total distance, mean dive duration and mean depth duration) between the first trip performed following capture and handling and the subsequent trip. nor were there any obvious behavioural changes observed upon the release of instrumented mothers and their pups in the treatment groups; all pairs showed apparently normal behaviour when reunited, as has been reported in previous studies (doidge et al. 1986, but also see geertsen et al. 2004; hooker et al. 2007; walker et al. 2012). despite having undergone what is likely a moderately stressful experience (the capture and instrument deployment) immediately prior to the first trip, behaviour during this first trip to sea did not differ from the subsequent trip in any manner that was measured. consequently, using data table 6 summary statistics for haulout periods and trip durations for seals equipped with satellite relay data loggers (srdls) or mk6 time�depth recorders (tdrs) at bouvetøya in 2000/01 and 2001/02. haulout duration (h) trip duration (h) season deployed instrument seal id no. mean sd n mean sd n 2000/01 srdls bv1-1553-00 53.5 10.8 5 151.2 61.5 6 2000/01 bv1-22497-00 34.4 10.5 9 75.2 46.5 10 2000/01 bv1-2848-00 59.2 26.1 5 118.1 55.9 6 2001/02 bv2-28489-01 38.7 15.9 8 79.7 25.7 9 2001/02 bv2-28490-01 52.3 16 6 126.6 29.7 7 2001/02 bv2-28491-01 33.8 10.2 10 72.3 17.3 11 mean 45.3 10.9 103.9 32.7 2000/01 tdrs bv1-003-00 32.7 9.6 8 72.9 70.2 9 2000/01 bv1-024-00 44.5 11.4 5 110.3 37.9 6 2000/01 bv1-033-00 30.8 7.7 9 64.4 17.3 10 2000/01 bv1-043-00 42.8 36.7 8 44.7 61.4 9 2000/01 bv1-052-00 29.6 19.8 10 44.6 28.3 11 2000/01 bv1-073-00 36.6 13.4 7 61.3 53.6 8 2000/01 bv1-092-00 35.4 13.2 6 85 27.4 7 2000/01 bv1-094-00 21.6 7.8 8 60.5 37.8 9 2000/01 bv1-113-00 96.7 37.8 2 17.9 11 3 2001/02 bv2-468-01 22.8 9.5 10 50.1 20.3 11 2001/02 bv2-479-01 33.8 28.8 6 77.1 34.4 7 2001/02 bv2-587-01 32.5 14.1 6 87 41.5 7 2001/02 bv2-777-01 31.3 0.2 2 72.9 15.3 3 2001/02 bv2-438-01 28.3 9 8 53.6 39.1 9 2001/02 bv2-758-01 33.4 8.1 8 61.9 17.5 9 2001/02 bv2-999-01 40.3 13.9 6 82.1 24.5 7 mean 37.7 17 65.4 21.5 instrumentation and handling effects on antarctic fur seals m.-a. blanchet et al. 6 (page number not for citation purpose) citation: polar research 2014, 33, 21630, http://dx.doi.org/10.3402/polar.v33.21630 http://www.polarresearch.net/index.php/polar/article/view/21630 http://dx.doi.org/10.3402/polar.v33.21630 from the first trip after instrumentation or deploying instruments on a large number of animals for only one or two trips in order to increase the sample size (and minimize the risk of longer-term deployments) seems to be a reasonable protocol for afs studies. afs females instrumented with larger instruments (srdls�vhfs) in this study performed substantially longer trips than those carrying smaller instruments (tdrs�vhfs). similar findings have been shown for various other marine mammal species (baker & johanos 2002; walker et al. 2012) and penguins (croll et al. 1991; ropert-coudert, wilson et al. 2007). in previous studies, afss carrying vhfs �tdrs showed extended attendance patterns compared to those carrying only vhfs (walker & boveng 1995). boyd et al. (1997) purposely studied the consequences of adding drag and increasing the cost of transport on lactating females of this species by attaching a wooden block on the animals’ backs, mimicking the shape and position of an instrument similar to the srdls used in this study. these authors also found that animals carrying the largest and heaviest load performed longer trips. in other species, such as the juan fernández fur seal (arctocephalus philipii), the first trip of females carrying a tdr was up to four times longer than trips performed by females carrying no instrument (francis et al. 1998). but, in contrast boyd et al. (1991) did not find any difference in attendance patterns between afs with and without tdrs. 4 0 10 20 30 40 50 6 8 10 12 age (d) p u p m a ss ( kg ) srdl tdr fig. 1 mass versus age for pups of females instrumented with satellite relay data loggers (srdls), time�depth recorders (tdrs) and very high frequency radio transmitters (vhfs) during the 2000/01 and 2001/02 austral summers at bouvetøya. the fitted lines represent predictions from a linear mixed-effects model describing pup mass as a function of the age and the instrument type carried by the mother. table 7 summary of linear mixed models fitted to explain the variability in attendance patterns, dives parameters and pup growth rates between the two instrument groups: satellite data relay loggers (sdrls) in combination with very high frequency radio transmitters (vhfs); and time�depth recorders (tdrs) combined with vhfs. for dive depth and dive duration, the values in parenthesis correspond to the entire data set while the others correspond to a random sample of 30% of the recorded dives. the p-values in boldface are significantly different between the two instrument groups. the reference level for the instrument factor is ‘‘srdl’’ and ‘‘2000/01’’ for the year. trip parameter model term value se df p trip duration intercept 63.85 16.73 166 b0.001 instrument (tdr) �2.13 0.68 19 b0.01 date 0.00 0.00 166 b0.01 year (2001/02) 0.37 0.62 19 0.56 haulout duration intercept �188.13 141.42 144 0.18 instrument (tdr) �9.51 5.02 20 0.07 date 0.00 0.00 144 0.09 year (2001/02) �6.21 4.60 20 0.18 dive depth a intercept 7.79 (6.79) 0.50 26 318 b0.001 instrument (tdr) �0.09 ( �0.1) 0.08 19 0.25 (0.24) date 0.00 0.00 26 318 b0.001 year (2001/02) 0.28 0.07 19 b0.001 dive duration a intercept 5.45 (5.58) 0.46 26 318 b0.001 instrument (tdr) 0.08 (0.07) 0.07 19 0.27 (0.33) date 0.00 0.00 26 318 b0.001 year (2001/02) 0.17 0.58 19 b0.05 pup mass intercept 5.14 0.40 88 b0.001 age 0.08 0.01 83 b0.001 instrument (tdr) �0.22 0.50 29 0.66 instrument (vhf) �0.37 0.53 29 0.48 sex (m) 0.47 0.40 29 0.25 age �instrument (tdr) 0.03 0.01 88 b0.05 age �instrument (vhf) 0.00 0.01 88 0.89 age �sex (m) 0.01 0.01 88 0.14 a parameters log-transformed. m.-a. blanchet et al. instrumentation and handling effects on antarctic fur seals citation: polar research 2014, 33, 21630, http://dx.doi.org/10.3402/polar.v33.21630 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21630 http://dx.doi.org/10.3402/polar.v33.21630 foraging trip and haulout durations are usually correlated in afs activity records (costa et al. 1989; boyd et al. 1991). but, in the present study, no significant difference in haulout duration was observed between the two instrument groups, despite the significant difference in at-sea trip duration. it is possible that an existing difference went undetected because of our relatively small sample sizes (see walker & boveng 1995), but it seems more likely that additional foraging costs were met via spending more time at sea, but this fact did not impact how long it takes to provision the pup with available milk stores before needing to again access food to restart the cycle. the increased trip duration observed could be related to lower prey capture rates as a consequence of the added drag, but is more likely due to increased costs to the female of swimming and diving. hydrodynamic shape, density and position of a tag are known to affect streamlining and therefore the efficiency with which the animals move in a fluid (wilson et al. 1986; agnew 2004; hooker et al. 2007; walker et al. 2012). instrument mass is likely of relatively minor importance for most marine mammal deployments because the instruments are close to being neutrally buoyant and are usually b5% of the animal’s body mass; in this study equipment mass was a maximum of 1% of body mass (see hawkins 2004; walker et al. 2012). boyd et al. (1997) showed that animals with larger, heavier tags swam slower both during surface swimming and diving compared to animals with smaller tags, although the present study did not detect any difference in dive depth or dive duration between the two groups with srdls and tdrs. if the net energy gain per dive is decreased due to increased drag of larger instruments, the animals might have to stay longer at sea in order to meet their energetic requirements before returning to the colony to feed their pup if they do not increase the time spent in individual dives. increased foraging costs do occur naturally in fur seals in periods of reduced prey abundance (boyd et al. 1991; boyd et al. 1994) with the consequence of increased time spent at sea under such circumstances, comparable to the situation observed in the present study with the largest tags. foraging in female fur seals is influenced by two contrasting mechanisms: the amount of energy the female can store, while meeting her own energy needs, and the amount of time she can spend at sea, which is dependent on the pup’s fasting abilities (costa et al. 1989; boyd et al. 1991; arnould et al. 1996). if the female’s energy expenditure at sea increases, the time needed to replenish her energy stores and accumulate new reserves to produce milk will increase but she will still be constrained by the pup’s fasting limits. if the females cannot spend the necessary time at sea to recoup their metabolic and milk production costs, they will be forced to use more body reserves or lower energy delivery to the pup (or a combination). in the present study, srdl animals lost on average twice as much mass per day (and total mass) compared to tdr animals, although this difference was not statistically significant. small sample size (nsrdl �5) and high individual variance typically observed in afs foraging behaviour (walker & boveng 1995) limit the power to detect differences between groups in this study. boyd et al. (1997) reported a mass loss of 2 kg more for treatment animals (large instrument n �6) compared to control animals (small instrument n �8), but similarly failed to detect a statistically significant difference. it is difficult to assess if larger instruments would have any negative long-term effects on the carriers. the present study and that of boyd et al. (1997) lasted for only the first third of the lactation period, though this does cover the most energetically demanding period for the females. milk production decreases approximately 80 days after birth (arnould 1996; arnould et al. 1996) and the females might then be able to allocate more energy to replenish their own energy reserves regardless of the added foraging cost. several factors are known to influence afs pup growth rates, such as sex, prey availability (vargas et al. 2009) and mass loss rates during the fasting periods while their mother is at sea (guinet et al. 1999). in the present study, sample sizes were too small to assess potential effects of sex and year but a significant difference in growth rate was detected with pups of srdls mothers growing more slowly. however, it should be noted that both sets of pups remained within the range of pup growth rates described in the scientific literature for afs from south georgia and macquarie island (lunn et al. 1993; guinet et al. 1999; vargas et al. 2009). both sexes were represented within each treatment group but, due to the unbalanced number of srdls and tdrs, there were more females in the tdr group. however, this lack of balance is counter to the trend observed between the equipment treatment groups because females normally have slower growth rates than males (guinet et al. 1999; vargas et al. 2009). in conclusion, this study showed that data from the first trip after instrumentation is representative of subsequent trips and that handling does not appear to have any measurable effect on the parameters explored. therefore, deploying instruments on a large number of animals for only one or two trips in order to increase the sample size (and minimize the risk of longer-term deployment costs) seems to be a reasonable protocol for afs studies. secondly, larger instruments seem to have at least temporary negative effects on lactating afss and instrumentation and handling effects on antarctic fur seals m.-a. blanchet et al. 8 (page number not for citation purpose) citation: polar research 2014, 33, 21630, http://dx.doi.org/10.3402/polar.v33.21630 http://www.polarresearch.net/index.php/polar/article/view/21630 http://dx.doi.org/10.3402/polar.v33.21630 their pups. at-sea time was significantly longer for animals with larger instruments and pup growth was significantly lower, suggesting that larger instruments should be used for only short periods, or that the shape of the instruments should be altered prior to being used again on this species. lastly, instrument effects should be taken into account when comparing time series collected under different equipment deployment regimes in order to avoid false conclusions regarding interannual variation or other explanatory variables. acknowledgements this work was funded by a norwegian antarctic research expedition grant awarded to kmk and cl by the norwegian research council. the authors thank aline arriola and petrus kritzinger (2007/08), brian flascas and ludvig krag (2001/02) and chuck brady, bianca harck and dave keith (2000/01) for their assistance in the field. logistics support was provided by the norwegian polar institute’s operations and logistics department and the logistics division of the south africa national antarctic programme. we thank marthán bester for his help with logistical arrangements and other support, the captain and crew of the s.a. agulhas for transport to and from the island and titan helicopters ltd for cargo and personnel transfer between the ship and the island. mb is currently at akvaplan-niva, fram centre, no-9296, tromsø, norway, and gh is at the port elizabeth museum at bayworld, humewood 6013, port elizabeth, south africa. references agnew d.j. 2004. the ccamlr ecosystem monitoring programme. antarctic science 9, 235�242. arnould j.p.y. 1996. lactation and the cost of pup rearing in antarctic fur seals. marine mammals science 13, 516�526. arnould j.p.y., boyd i.l. & speakman j.r. 1996. the relationship between foraging behaviour and energy expenditure in antarctic fur seals. journal of zoology 239, 769�782. baker j.d. & johanos t.c. 2002. effect of research handling on the endangered hawaiian monk seal. marine mammal science 18, 500�512. beauplet g., dubroca l., guinet c., cherel y., dabin w., gagne c. & hindell m. 2004. foraging ecology of subantarctic fur seals arctocephalus tropicalis breeding on amsterdam island: seasonal changes in relation to maternal characteristics and pup growth. marine ecology progress series 273, 211�225. biuw m., krafft b.a., hofmeyr g., lydersen c. & kovacs k.m. 2009. time budgets and at-sea behaviour of lactating female antarctic fur seals arctocephalus gazella at bouvetøya. marine ecology progress series 385, 271�284. biuw m., nøst o.a., stien a., zhou q., lydersen c. & kovacs k.m. 2010. effects of hydrographic variability on the spatial, seasonal and diel diving patterns of southern elephant seals in the eastern weddell sea. plos one 5(11), e13816, doi: 10.1371/journal.pone.0013816. bonner w.n. 1968. the fur seal of south georgia. british antarctic survey report 56. london: british antarctic survey. boyd i.l. 1999. foraging and provisioning in antarctic fur seals: interannual variability in time�energy. behavioural ecology 10, 198�208. boyd i.l., arnould j.p.y., barton t. & croxall j.p. 1994. foraging behaviour of antarctic fur seals during periods of contrasting prey abundance. journal of animal ecology 63, 703�713. boyd i.l., kato a. & ropert-couderc y. 2004. bio-logging science: sensing beyond the boundaries. memoirs of the national institute of polar research special issue 58, 1�14. boyd i.l., lunn n.j. & barton t. 1991. time budget and foraging characteristics of lactating antarctic fur seals. journal of animal ecology 60, 577�592. boyd i.l., mccafferty d.j. & walker t.r. 1997. variation in effort by lactating antarctic fur seals: response to simulated increased foraging costs. behavioral ecology and sociobiology 40, 135�144. casper r.m., sumner m.d., hindell m.a., gales n.j., staniland i.j. & goldsworthy s.d. 2010. the influence of diet on foraging habitat models: a case study using nursing antarctic fur seals. ecography 33, 748�759. costa d.p., croxall j.p. & duck c. 1989. foraging energetics of antarctic fur seals in relation to changes in prey availability. ecology 70, 596�606. croll d.a., osmek s.d. & bengtson j.l. 1991. an effect of instrument attachment in foraging trip duration in chinstrap penguins. the condor 93, 777�779. david j.h.m., meyer m.a. & best p.b. 1990. the capture, handling and marking of free-ranging adult south-african (cape) fur seals. south african journal of wildlife research 20, 5�8. doidge d.w., mccann t.s. & croxall j.p. 1986. attendance behaviour of antarctic fur seal. in r.l. gentry & g.l. kooyman (eds.): fur seals: maternal strategies on land and at sea. pp. 102�115. princeton, nj: princeton university press. fedak m.a., lovell p. & grant s.m. 2001. two approaches to compressing and interpreting time-depth information as collected by time�depth recorders and satellite-linked data recorders. marine mammal science 17, 94�110. field i., harcourt r., de bruyn p.j.n., boehme l., charrassin j.-b., mcmahon c.r., bester m.n., fedak m. & hindell m.a. 2012. refining instrument attachment on phocid seals. marine mammal science 28, e325�e332. francis j., boness d. & ochoa-acuña h. 1998. a protracted foraging and attendance cycle in female juan fernández fur seals. marine mammal science 14, 552�574. freitas c., lydersen c., fedak m. & kovacs k.m. 2008. a simple new algorithm to filter marine mammal argos location. marine mammal science 24, 315�325. m.-a. blanchet et al. instrumentation and handling effects on antarctic fur seals citation: polar research 2014, 33, 21630, http://dx.doi.org/10.3402/polar.v33.21630 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21630 http://dx.doi.org/10.3402/polar.v33.21630 gastebois c., viviant m. & guinet c. 2011. ontogeny of aquatic behaviours in antarctic fur seal (arctocephalus gazella) pups in relation to growth performances at kerguelen islands. polar biology 34, 1097�1103. geertsen b.m., teilmann r.a., kastelein h.n.j., vlemmix h.n.j. & miller l.a. 2004. behaviour and physiological effects of transmitter attachments on a captive harbour porpoise (phocoena phocoena). journal of cetacean research management 6, 139�146. goldsworthy s.d., page b., welling a., chambellant m. & bradshaw c.j.a. 2010. selection of diving strategy by antarctic fur seals depends on where and when foraging takes place. marine ecology progress series 400, 255�266. guinet c., goldworthy s.d. & robinson s. 1999. sex differences in mass loss rate and growth efficiency in antarctic fur seals (arctocephalus gazella) pups at macquarie island. behavioral ecology and sociobiology 46, 157�163. guinet c., lea m.-a. & goldsworthy s.d. 2000. mass change in antarctic fur seal (arctocephalus gazella) pups in relation to maternal characteristics at the kerguèlen islands. canadian journal of zoology 78, 1�8. hawkins p. 2004. bio-logging and animal welfare: practical refinements. memoirs of the national institute of polar research special issue 58, 68�68. heaslip s.g. & hooker s.k. 2008. effect of animal-borne camera and flash on the diving behaviour of the female antarctic fur seals (arctocephalus gazella). deep-sea research part i 55, 1179�1192. hooker s.k., biuw m., mcconnell b., miller p.o. & sparling c.e. 2007. bio-logging science: logging and relaying physical and biological data using animal-attached tags. deep-sea research part ii 54, 177�182. kovacs k.m. & lavigne d.m. 1992. maternal investment in otariid seals and walruses. canadian journal of zoology 70, 1953�1964. littnan c.l., baker j.d. & parrish f.a. 2004. effect of video camera attachment on the foraging behaviour of hawaiian monk seals. marine mammal science 20, 345�352. lunn n.j., boyd i.l., barton t. & croxall j.p. 1993. factors affecting the growth rate and mass at weaning of antarctic fur seals at bird island, south georgia. journal of mammalogy 74, 908�919. mccafferty d.j., boyd i.l., walker t.r. & taylor r.i. 1998. foraging responses of antarctic fur seals to changes in the marine environment. marine ecology progress series 166, 285�299. mccafferty d.j., currie j. & sparling c. 2007. the effect if instrument attachment on the surface temperature of juvenile grey seals (halichoerus grypus) as measured by infrared thermography. deep-sea research part ii 54, 424�436. mcmahon c.r., filed i.c., bradshaw c.j.a., white g.c. & hindell m.a. 2008. tracking and data-logging devices attached to elephant seals do not affect individual mass gain or survival. journal of experimental marine biology and ecology 360, 71�77. r development core team r 2009. r: a language and environment for statistical computing. vienna: r foundation for statistical computing. ropert-coudert y., knott n., chiaradia a. & kato a. 2007. how different data logger sizes and attachment positions affect the diving behaviour of little penguins? deep-sea research part ii 54, 415�423. ropert-coudert y., wilson r., yoda k. & kato a. 2007. assessing performance constraints in penguins with externally-attached devices. marine ecology progress series 333, 281�289. rutz c. & hays g.c. 2009. new frontiers in biologging science. biology letters 5, 289�292. staniland i.j., boyd i.l. & reid k. 2007. an energy�distance trade-of in a central-place forager, the antarctic fur seal (arctocephalus gazella). marine biology 152, 233�241. trathan p.n. & croxall j.p. 2004. marine predators at south georgia: an overview of recent bio-logging studies. memoirs of the national institute of polar research special issue 58, 118� 132. vargas r., osman l. & torres d. 2009. inter-sexual differences in antarctic fur seal pup growth rates: evidence of environmental regulation? polar biology 32, 1177�1186. walker b. & boveng p. 1995. effect of time�depth recorders on maternal foraging and attendance behaviour of antarctic fur seals (arctocephalus gazella). canadian journal of zoology 73, 1538�1544. walker k.a., trites a.w., haulena m. & weary d.m. 2012. a review of the effects of different marking and tagging techniques on marine mammals. wildlife research 39, 15�30. weimerskirch h., shaffer s.a., mabille g., martin j., boutard o. & rouanet j.l. 2002. heart rate and energy expenditure of incubating wandering albatrosses: basal levels, natural variation, and the effects of human disturbance. journal of experimental biology 205, 475�483. wilson r.p. & macmahon c.r. 2006. measuring devices on wild animals: what constitutes acceptable practice? frontiers in ecology and the environment 4, 147�154. wilson r.p., stewart w.g. & cuffy d.c. 1986. recording devices on free-ranging marine animals: does measurement affect foraging performance? ecology 67, 1091�1093. instrumentation and handling effects on antarctic fur seals m.-a. blanchet et al. 10 (page number not for citation purpose) citation: polar research 2014, 33, 21630, http://dx.doi.org/10.3402/polar.v33.21630 http://www.polarresearch.net/index.php/polar/article/view/21630 http://dx.doi.org/10.3402/polar.v33.21630 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <feff004700650062007200750069006b002000640065007a006500200069006e007300740065006c006c0069006e00670065006e0020006f006d00200064006500200063006f006d007000610074006900620069006c006900740065006900740020006d006500740020005000440046002f0058002d003300200074006500200063006f006e00740072006f006c006500720065006e00200065006e00200061006c006c00650065006e0020005000440046002d0064006f00630075006d0065006e00740065006e002000740065002000700072006f006400750063006500720065006e002000640069006500200063006f006d007000610074006900620065006c0020007a0069006a006e002e0020005000440046002f0058002000690073002000650065006e002000490053004f002d007300740061006e0064006100610072006400200076006f006f00720020006800650074002000750069007400770069007300730065006c0065006e002000760061006e002000670072006100660069007300630068006500200069006e0068006f00750064002e002000520061006100640070006c0065006500670020006400650020006700650062007200750069006b00650072007300680061006e0064006c0065006900640069006e0067002000760061006e0020004100630072006f00620061007400200076006f006f00720020006d00650065007200200069006e0066006f0072006d00610074006900650020006f00760065007200200068006500740020006d0061006b0065006e002000760061006e0020005000440046002d0064006f00630075006d0065006e00740065006e002000640069006500200063006f006d007000610074006900620065006c0020007a0069006a006e0020006d006500740020005000440046002f0058002d0033002e0020004400650020005000440046002d0064006f00630075006d0065006e00740065006e0020006b0075006e006e0065006e00200077006f007200640065006e002000670065006f00700065006e00640020006d006500740020004100630072006f00620061007400200065006e002000520065006100640065007200200034002e003000200065006e00200068006f006700650072002e> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice book review book review review of expedition relics from high arctic greenland—eight decades of exploration history told through 102 objects, by peter r. dawes (2023). copenhagen: museum tusculanum press. 500 pp. isbn 987 87 635 46867.   citation: polar research 2023, 42, 9614, http://dx.doi.org/10.33265/polar.v42.9614 copyright: polar research 2023. © 2023 kyrre reymert. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 17 may 2023 correspondence per kyrre reymert, tromsø, norway. e-mail: p-reyme@online.no   books about polar expeditions are usually stories of an explorer, an expedition, a vessel, a geographical discovery or a tragedy. in expedition relics from high arctic greenland—eight decades of exploration history told through 102 objects, peter r. dawes takes a different starting point: the artefacts found long afterward. through these objects and dawes’ descriptions of how they came to northernmost greenland, the reader meets the explorers and their ships, feats and tragedies, as well as the inuit people who contributed to the success of the expeditions. a decisive event for dawes occurred in 1965, when he watched the eminent danish archaeologist eigil knuth (1903–1996) excavate a whaling boat, dating to 1875. “from then on i was hooked on polar exploration history, intrigued by a region where intrinsic remains of dramatic events lay undisturbed in their hiding places for almost a hundred years” (p. 41). dawes, a geologist, joined the geological survey of greenland in 1965, and was then with its successor, the geological survey of denmark and greenland. it was during dawes’ fieldwork for these organizations, in the period 1965–2001, that the artefacts featured in the book were collected. they were collected opportunistically by dawes and his co-workers as a secondary pursuit spurred by an interest in exploration history rather than in the systematic manner that characterizes modern archaeology, in which investigations are structured to answer particular questions and are typically backed by a university, museum or government agency. one might even say that the objects were collected as souvenirs. but whereas tourist souvenirs remain private, the objects in dawes’ collection are being made available to the public. they were exhibited at the danish arctic institute’s arctic house, in copenhagen, from 14 december 2022 until mid-march 2023. upon the book’s general release (scheduled for may this year), the objects will be given to the greenland national museum and archives (nunatta katersugaasivia allagaateqarfialu), in nuuk. (the group of objects that are referred to in the book as the “22 relics” are already in public collections.) moreover, the objects are—in contrast to most souvenirs—exceptionally well described and their history painstakingly presented. the discoveries were made at 32 “historic sites”, some of which were marked by building foundations or other fixed remains, whereas other such cultural heritage sites had only loose artefacts that lay on the surface or were partially visible in the ground. (object 3 was lifted out with the “gentle use of a geological hammer” [p. 162].) not all of the objects at a site were collected. for example, just two ship fittings were taken “from the many metal objects” that were found at one overwintering site (p. 192). some artefacts were seen one year and collected another. amateur archaeological excavation methods, carried out by dawes, were used in a very few cases, including “the excavation of ruined igloos and associated stratified deposits (ceramics, glass, metal, rubber, wood)” (p. 92). the “102 artefacts” in the book’s title consist of two groups. one is a group of “80 objects.” thirty-five of these 80 objects were found in northeast greenland national park (nationalparken i nordog østgrønland), which, starting in 1980, prohibits interference with permanent cultural remains, and artefacts associated with those remains, that predate 1900. from what this reviewer can determine, eight of the objects that predate 1900 were collected after 1980, but dawes doesn’t explain if he was granted special permission for this. the second group comprises “22 relics” collected at the same time as the 80 described here. what sets the 22 relics apart is that they have already been handed over to museums and other public collections. the 102 items include personal effects, field equipment, provisions and documents and are made of material such as bone, glass, ivory, metal, wood, leather and paper, preserved by north-west greenland’s dry climate; its harshness and remoteness, which has severely limited human visits, has also helped. eighty-eight of the objects are european or american, six are of inuit origin and eight are of mixed origin. the objects are associated with 19 us, british and danish expeditions to north-east greenland from the years 1853–55 to 1934–35. the northernmost find was made at 83°30’n, merely 700 km shy of the north pole. the region is truly high arctic, the northernmost dry land on the globe. the expeditions’ purposes were discovery, mapping, research, searching for lost expeditions and occupying territories for a nation. according to dawes, the geographical area of the book was a “geopolitical void” and the flags of the usa, great britain and denmark “were unfurled ceremoniously in acts of territorial possession” (p. 23). dawes’ project began as a set of brief descriptions of the type conventionally found in a museum—“a straightforward listing of the various objects in my possession, with as much information as could be written on a standard docket label” (p. 46). but as dawes elaborated on the history of each of the discoveries, his “simplistic plan soon needed modification. determining the provenance, age and functionality of some of the artefacts turned out to be compelling and indeed more fascinating than foreseen” (p. 46). following introductory chapters that offer the author’s personal reflections as well as background information about arctic archaeology, how cultural remains fare over time, various kinds of historic sites and other pertinent matters, the objects are presented, organized chronologically by expedition. the dimensions and condition of each object are provided, along with its place and date of discovery, the collector’s name, historical events associated with the site, information about other cultural remains there, dawes’ interpretation of the object and whether any objects were left behind. the “80 objects” are described in greatest detail. descriptions of the “22 relics” are shorter; the reader is referred to information in the museums and other collections where they are kept. the book’s approximately 600 illustrations are nicely printed and well captioned. for each artefact there are old and new photographs, drawings and maps that richly illustrate the location, the expedition and its participants. roberto fortuna’s photographs of the objects are outstanding and include close-ups that show details that are discussed in the text. in my view as an archaeologist, the documentation of the objects would have benefitted from photographs taken in situ in the field, before they were removed. the geographical coordinates of the discovery sites should also have been provided, although they can be roughly determined from the large map at the end of the book, which marks the location of each find. devoted to discoveries dating from the mid-19th century to the early 20th century, the book falls under what is called historical archaeology. why should one bother with archaeological objects from a period that is amply documented by archival resources and contemporary published accounts? bjarne grønnow, professor of arctic archaeology at the national museum of denmark, explains in the book’s foreword that historical archaeology may “provide entirely new perspectives on past events”: inconspicuous finds of fragmented tools, implements, containers, clothes, personal possessions, and the like … form ‘windows’ into aspects of past human life which rarely have found their way into written accounts and archives. many events of contemporary interest were simply considered too common to be described. (p. 14) objects used in the daily lives of expedition members were often not considered important enough to be mentioned in written records, but they were left behind by shore parties or at overwintering sites and shed light on the everyday lives of the people who used them. artefacts can also provide insight into interactions between those in lower positions on the expedition ships and the inuit, something that is often omitted from expedition reports. some objects in the book were made by inuit and were then reused and adapted across ethnic boundaries. such objects—dawes calls them “hybrids”—are intriguing evidence of cross-cultural encounters under extreme conditions. object 71, an inuit oil lamp made of copper, is one such artefact. through an exciting and knowledgeable exposition, dawes links the object to a specific expedition among several possible expeditions. this is a cultural–historical investigation of the best kind. many inuits are depicted in the text and in a gallery of photographic portraits, since their practical help and work, as paid dog-sled drivers, for example, were often decisive for the expeditions’ completion. the people of the region—mainly inughuit—moved to the expeditions’ campsites or the expeditions overwintered where the inuits were. boat party hut is at one such site; others include the remains of fixed structures at etah, thank god harbour and polaris beach. during his many years of fieldwork in north-east greenland, dawes came to know the inuit well and gained great respect for their knowledge of the land and how to travel on it. another interesting aspect of the book is that it covers the graves of expedition members. approximately 40 graves were known from the period 1849 to 1917, but dawes has managed to find information that boosts the number above 50. also fascinating is the section on cairns. as a field geologist in greenland, dawes has seen many of these. they served as way or landmarks, look-out points or memorials, marked depots or were used for mapping or signalling. some cairns had several of these functions and all could be used as a place to leave messages. the “22 relics” were collected from cairns. expedition relics from high arctic greenland is a thick book in a format nearly as tall as an a4 sheet of paper and somewhat wider. the text is arranged in two columns, with good margins, and only a handful of spreads lack illustrations, which makes the book easy to read. two large overview maps are located inside the front and back covers. there is a nine-page list of european and inuit place names, as well as an eight-page list of personal names. the bibliography is a full 13 pages and very good. the book has few defects. in addition to a couple of flaws that have already been mentioned here, there is the somewhat confusing use of the terms “object”, “artefact” and “relic”. as counted by this reviewer, the “80 objects” actually comprise 130 individual objects (e.g., one “object” comprised 18 iron nails; another was six wooden buttons), and the “22 relics already in safekeeping” are, in fact, 36 items. some gaps and discrepancies in pagination mar an otherwise very handsomely put-together book. the reader curious about the western exploration of north-west greenland and the inuit who played a role in this endeavour during the 19th and early 20th centuries will find nothing more gripping, more thoroughly researched or better illustrated than dawes’ expedition relics from high arctic greenland. dawes argues that collecting the artefacts, through which he tells the stories of the expeditions, was necessary and urgent on account of the far north’s rapidly changing climate in the north, which raises the risk of the artefacts’ degradation. rising human traffic, especially by tourists, is also a danger. the magnetic method as a tool to investigate the werenskioldbreen environment (south-west spitsbergen, arctic norway) research article the magnetic method as a tool to investigate the werenskioldbreen environment (south-west spitsbergen, arctic norway) magdalena gwizdałaa, maria jeleńskaa & leszek łęczyńskib adepartment of magnetism, institute of geophysics, polish academy of sciences, warsaw, poland; binstitute of oceanography, university of gdańsk, gdynia, poland abstract we used a novel approach of applying magnetic analyses to investigate the material released from the receding glacier werenskioldbreen on spitsbergen, svalbard, arctic norway. surface sediments were taken from the bay nottinghambukta and the werenskioldbreen foreland, along two main proglacial streams. magnetic analyses, namely the low-field mass magnetic susceptibility, anhysteretic susceptibility mass normalized and hysteresis parameters, served to determine magnetic properties and identify the magnetic composition of the study material. we selected two distinct types of sediments. the first group, consisting of magnetite and pyrrhotite, has more single-domain grains in comparison to the second one, containing only magnetite. in the second group, multi-domain particles dominate. deposits from the north stream, glacier river and an area close to the estuary of nottinghambukta include magnetite and pyrrhotite. magnetite was found in the south stream and in the outside part of the bay. magnetic composition reflects different source rocks of sediments. this study demonstrates the utility of the magnetic method in analysing the current state of glacier environments. keywords environmental magnetism; glacier environment; surface sediments; svalbard; magnetic susceptibility abbreviations κ(t): low-field volume magnetic susceptibility dependence on temperature; md: multi-domain particles; sd: single-domain particles; χarm: mass-normalized anhysteretic susceptibility; χlf: low-field mass magnetic susceptibility introduction global climate change has a significant effect on polar regions. the arctic environment is rapidly changing. annual and seasonal temperatures have been rising in the arctic, and sea-ice volume and extent have been declining (solomon et al. 2007; kwok et al. 2009). to understand such changes, there is a need to investigate natural archives, such as marine sediments, soil and ice cores, especially in polar regions, where the magnitude of expected changes is the most distinct and rapid (e.g.,holland & bitz 2003; miller et al. 2010; stocker et al. 2013; thienpont et al. 2015). glacier melting is one of the environment’s responses to global climate change; therefore, it is very important to understand this process and its extent through the application of standard and non-standard methods. environmental magnetism is a multidisciplinary subject that connects research on a wide range of topics (e.g., evans & heller 2003). all materials respond to an applied magnetic field. iron-bearing minerals are sensitive to environmental processes, which makes magnetic techniques highly useful for detecting signals associated with natural processes. in environmental magnetism, rock and mineral magnetic methods are used to study the formation, transportation, deposition and postdepositional modifications of magnetic minerals under the impacts of a wide range of natural processes (e.g., liu et al. 2012). reports documenting the application of the magnetic methods to investigate glacial environment are mainly focused on climatic changes in sedimentary sequences (e.g., lanci et al. 1999; sagnotti et al. 2001; hirt et al. 2003; hatfield et al. 2016) or ice sequences (e.g., lanci et al. 2001; lanci & delmonte 2013). this paper presents the application of magnetic analyses to the study of the current state of glacier environment. this novel approach can provide new information in the area of glacier study. study area the glacier werenskioldbreen is located in the southwestern part of wedel jarlsberg land on spitsbergen, svalbard, arctic norway (fig. 1). the glacier is 9.5 km long (hagen & lefauconnier 1995) and covers 44.1 km2, of which 61% are glaciated (ignatiuk et al. 2014). the werenskioldbreen catchment area includes two main proglacial streams, separated by a medial moraine, and is closed by an ice-cored frontal moraine from the west (majchrowska et al. 2015). the thickness of werenskioldbreen is around 100–140 m, with a surface layer of cold ice (50 –100 m) and temperate ice below (pälli et al. 2003). this polythermal glacier, terminating on land, has been in contact magdalena gwizdała mgwizdala@igf.edu.pl department of magnetism, institute of geophysics, polish academy of sciences, ksiecia janusza 64, warsaw 01-452, poland polar research, 2018 vol. 37, 1436846 https://doi.org/10.1080/17518369.2018.1436846 © 2018 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2018.1436846&domain=pdf a state of constant recession since the 1920s (kosiba 1960). geologically, werenskioldbreen is located in the contact zone of three tectonic blocks of the hecla hoek succession (fig. 1; czerny et al. 1993). the hecla hoek succession is a collection of rocks older than devonian, and involved in caledonian orogenic deformation in svalbard (birkenmajer 1990). the eimfjellet group underlies the southern and southwestern part of the glacier and includes amphibolite, quartzite and chlorite schist. the deilegga group, belonging to the north tectonic block, forms the eastern and northern part of the werenskioldbreen basin. it is mainly composed of phyllites with quartzite and silt intercalations, and calcareous and chlorite schists (kieres & piestrzynski 1992). the sofiebogen group, consisting of green schists, and muscovite–carbonate–quartz or carbonate–chlorite–quartz schists, is located in the north-western part of the basin. the sofiebogen group includes the elveflya formation, which consists of similar rocks. the proglacial area belongs to the sofiebogen and eimfjellet groups, where mica–carbonate–quartz and grey calcite marbles dominate (czerny et al. 1993). the isbjørnhamna group contains garne–mica schists intercalated with grey marbles alternating with schists, and underlies the area to the south of werenskioldbreen (birkenmajer 1990). the bay nottinghambukta is a very shallow embayment of the greenland sea (only 2.5 m below the lowest tide). the exposed surface can be more than 50% of the bay (giżejewski 1986). a delta, supplied by the proglacial streams of werenskioldbreen, progrades into the bay from the east. from the west, it is partially screened from the open sea by the dunøyane islands. nottinghambukta is a very young form, having been created by depositional activity of proglacial rivers and, at the same time, essentially influenced by marine processes, such as tides, waves and coastal currents (kowalska & sroka 2008). the research area is lithologically differentiated by the occurrence of different minerals with various magnetic properties (e.g., pyrrhotite, magnetite and hematite). magnetic properties of sediments are directly associated with the origin of detrital material and can vary depending on the mineralogy of the source rock, especially iron compounds, which makes it possible to determine the source of sediments. the primary aim of this paper is to provide a description of mineral material released from ice masses during the recession of werenskioldbreen, through the evaluation of their magnetic signature. methods sampling a total of 49 surface sediment samples were taken from the seafloor of nottinghambukta, along the two main proglacial streams, located in the north and in the south, and from the werenskioldbreen proglacial river formed by these streams (table 1, fig. 2). the streams are separated by a medial moraine and transport what is likely to be different material from the opposite sides of werenskioldbreen. specimens were taken close to watercourses, where material had recently been uncovered. marine sediment collection was performed from a pontoon equipped with the van veen grab sampler, from a depth of about 1–3 m. a sample of 1 kg was gathered from each sampling point. specimens were collected in 2015, transported to a laboratory and stored at −20°c. before measurements, sediment samples were dried to constant weight. characterization of study material studied material was characterized by means of grain-size determination. the analysis of grain size distribution was performed in the laboratory of applied geology of the institute of oceanography, university of gdańsk. grain size distribution was determined by dry sieving with nylon sieves. this analysis determines the particle size > 0.063 mm. results of sieve analysis were entered into gradistat programme (blott & pye 2001). using this protable 1. grouping of investigated samples into sets. set of samples sample nottinghambukta nb1-11 north stream wp100-119 south stream wp1-11 glacier river wp12-18 figure 1. lithostratigraphy of the werenskioldbreen basin, modified after stachnik et al. (2016). all subdivided units belong to the heckla hoek succession. 2 m. gwizdała et al. gramme, we calculated the mean grain size according to the formulas of folk & ward (1957). six types of grain size were separated based on the mean: coarse sand (> 500 µm), medium sand (250–500 µm), fine sand (125–250 µm), very fine sand (63–125 µm), very coarse silt (31–63 µm) and coarse silt (16–31 µm). the last two grain sizes were estimated only theoretically, by calculation. preliminary grain size distribution results showed that fine sand occurs close to the estuary in nottinghambukta (nb9-11). further away from the estuary (nb1-8), very fine sand and very coarse silt prevail. in the north stream, the main grain size is between coarse silt and medium sand, with very fine sand predominating. fine and very fine sand dominates in the south stream, with the exception of two samples (medium sand in sample wp1 and coarse sand in wp2), while the glacier river is additionally enriched with a finer fraction (very coarse and coarse silt). magnetic methods measurements of χlf were conducted using the mfk1-fa multi-function kappabridge instrument (agico, czech republic). anhysteretic remanence magnetization was measured by means of 2g squid cryogenic magnetometer. to acquire anhysteretic remanence magnetization, each sample was exposed to an alternating current magnetic field with peak field amplitude decreasing from 100 to 0 mt and a superimposed direct current bias field of 100 μt. χarm was obtained by dividing the anhysteretic remanence magnetization by the value of the direct current bias field. the χarm parameter served to determine the role of single-domain magnetite for material with one magnetic phase (e.g., magnetite). both χlf and χarm depend also on the concentration of magnetic minerals. identification of magnetic minerals was based on a thermomagnetic experiment: low-field volume magnetic susceptibility dependence on temperature – κ(t). the evolution of κ(t) experiments was measured using a kappabridge kly-3 with high-temperature extension cs-3 (agico). the experiment was conducted in the air during heating in the 20–700°c temperature range and cooling to 20°c. hysteresis loop measurements were performed at room temperature, using the vibrating sample magnetometer, produced by molspin (uk), and vibrational magnetometer micro-mag agfm 2900–02 (usa). sediment samples used for this experiment weighted 0.3 g and 0.006 g, respectively. both devices operated at the maximum magnetic field of 1 t. the hysteresis loops allowed for the determination of the coercivity (hc), saturation remanence (mrs) and saturation magnetization (ms). the coercivity of remanence (hcr) was determined using the curves of subsequent direct current back-field remagnetization of mrs. based on these parameters, a day-dunlop diagram (day et al. 1977; dunlop 2002a, b) was created. the domain state of magnetic grains was inferred from the position of data on the diagram in relation to the corresponding mixing lines. magnetic analyses were performed in the paleomagnetic laboratory of the institute of geophysics, polish academy of sciences, in warsaw. figure 2. location map of analysed samples (based on norwegian polar institute maps at http://toposvalbard.npolar.no/). the glacier front was drawn based on the landsat 8 satellite image from 8 september 2015 (available from the us geological survey at https://earthexplorer.usgs.gov/). polar research 3 http://toposvalbard.npolar.no/ https://earthexplorer.usgs.gov/ results and discussion magnetic analyses low-field susceptibility and anhysteretic susceptibility values varied considerably from sample to sample (figs. 3, 4). generally, χlf values were between 20 and 30 × 10−8m3/kg. however, the highest χlf value for nottinghambukta (70.81 × 10−8m3/kg) was obtained for the sample from the southernmost point of the bay (nb5), where boat launching occurred for many years. pollution by motor oil and other contamination of anthropogenic origin affect χlf, usually increasing its value. only in the middle part of the north stream, high values of 60.64–75.30 × 10−8m3/kg were detected. χarm values were in the range of 25.47–77.95 × 10−8m3/kg for nottinghambukta sediments, except for two specimens (nb8, nb11), which had higher values (χarm> 143 × 10−8m3/kg). samples from the north stream achieved the highest χarm values (87 <χarm< 234 × 10−8m3/kg), except for the first two specimens, for which χarm was about 23–33 × 10 −8m3/kg. by contrast, the south stream was characterized by a rather low χarm values (13.98 – 40.76 × 10 −8m3/kg), up to the area where both streams combine and create a glacier river. along the glacier river, χarm exceeded 79 × 10−8m3/kg. the variability seen in χlf and χarm results from the different bedrocks eroding along the north and the south streams. the geological unit along the latter – the elveflya formation – consists mainly of metamorphosed volcaniclastic rocks, while that along the north stream – the deilegga group – mainly comprises metamorphosed sedimentary rocks (fig. 1). figure 3. distribution of χlf in the investigated area (based on norwegian polar institute maps at http://toposvalbard.npolar.no/). figure 4. distribution of χarm in the investigated area (based on norwegian polar institute maps at http://toposvalbard.npolar.no/). 4 m. gwizdała et al. http://toposvalbard.npolar.no/ http://toposvalbard.npolar.no/ selected representative examples of the thermomagnetic curves are given in fig. 5. in fig. 5a and b, the heating curves have two peaks in temperatures just below 320°c and 590°c, the distinguishing curie temperatures for pyrrhotite and magnetite, respectively. the first peak below 320°c can be partly due to the hopkinson effect (hopkinson 1890) and partly to creating a new magnetic mineral. the pyrrhotite hopkinson peak is clearly visible on the cooling curve of partial κ(t) analysis (fig. 5c). the second peak probably results from magnetite formation due to heating. the heating curves also illustrate a plateau of susceptibility between 330°c and 440°c that can be interpreted as the occurrence of initial magnetite (fig. 5b). the newly formed magnetite dominates the initial magnetic mineralogy during cooling (fig. 5a). the decrease of κ on the cooling curve between 300°c and room temperature can be attributed to the progressing transformation of the newly formed magnetite. similar κ(t) curves were reported by crouzet et al. (2001) in himalayan metacarbonates and characterized as a hopkinson peak of pyrrhotite. these are typical curves for most nottinghambukta specimens, characteristic also of sediments from the north stream and the glacier river. heating curves of κ(t) for samples from the south stream and a few samples from the bay (nb1, nb3, nb5) are impeded by thermochemical changes above 400°c, which trigger the formation of new magnetite (fig. 5e). several κ (t) heating curves are relatively constant, until the temperature reaches 580–590°c, the curie point of magnetite, where susceptibility decreases to zero (fig. 5g, h; dunlop & özdemir 1997). the cooling curve shows the creation of magnetite at a temperature higher than 590°c. furthermore, all presented curves show a rather constant susceptibility in the low temperature range (up to 250°c) indicating a minor contribution of paramagnetic minerals to the bulk low-field susceptibility. to sum up, the sediments can be divided into two groups in terms of magnetic mineralogy: samples containing only magnetite and those with both magnetite and pyrrhotite. figure 6 shows examples of hysteresis loops for the samples with (fig. 6a, b) and without (fig. 6c, d) pyrrhotite. specimens with pyrrhotite exhibit a slightly wasp-waisted shape (fig. 6b). samples without pyrrhotite (with only magnetite) show a greater contribution of paramagnetic minerals (fig. 6c) than those with magnetite and pyrrhotite (fig. 6a). however, loops for both groups of specimens exhibit a ferrimagnetic behaviour. hysteresis parameters, present on the daydunlop graph, indicate the grain size of magnetic fraction. sediments under analysis are mainly a mixture of sd and md particles (fig. 7). however, samples occur mostly in the upper left part of the graph, where sd grains dominate. specimens from the outside part of nottinghambukta (nb1-3, nb5) and those from close to the front of werenskioldbreen (wp1-2, wp4-9, wp100-101, wp106, wp111) have a greater content of md particles. this division may be caused by the presence of pyrrhotite in samples from the upper left part of plot. the critical sd grain size for equidimensional pyrrhotite is 1.6 µm (dunlop & özdemir 1997). based on data from clark (1984), the values of magnetization and coercivity ratios for sd pyrrhotite are 0.407–0.474 and 1.35, respectively. peters & dekkers (2003) observed that this mineral affects the position of samples on a day-dunlop diagram by shifting it towards sd grains. the other indicators of magnetic grain size distribution and mineralogy are χarm versus χlf and χarm versus mrs relations (fig. 8). the plot of χarm versus χlf shows two linear trends (fig. 8a). a linear trend indicates a generally constant distribution of grain size and mineralogy (king et al. 1982). the two trends represent two groups of samples which differ in mineralogy and grainsize distribution. division between the studied sets of samples is clearly visible. most of the nottinghambukta sediments occur in the initial part of the first trend. the samples from the north stream and the glacier river are presented in the upper part of this trend, where two specimens from the bay (nb8 and nb11) are also placed. samples from the south stream and a few specimens from the north stream and the nottinghambukta (wp1-11, wp100-101, wp106107, nb1-3, nb5) are the basis of the second trend. the group of samples from the first trend is characterized by the 3.25–9.5 range of χarm/χlf values, while specimens from the second trend have this ratio mainly between 0.55 and 2.13. according to peters & dekkers (2003), these are the typical ranges for sd and md grains, respectively, assuming that the mixture of magnetite and pyrrhotite demonstrates similar properties of χarm/χlf as homogeneous magnetite. it means that pyrrhotite influences χarm value in a similar way as sd magnetite. the χarm versus mrs graph demonstrates concentration of sd grains in relation to the total grain size (fig. 8b). the relation between χarm and mrs forms one linear trend. particular groups of samples occupy different parts of the diagram. specimens nb1, wp100, wp101 and those from the south stream are clustered at the very beginning of the graph. next, there is the nottinghambukta set of samples, except for two specimens (nb8 and nb11), which are in the last group, with sediments from the glacier river and polar research 5 several samples from the north stream. these groups form a linear trend. samples plotted along this trend differ mainly in concentration. the north stream set of samples is slightly shifted from the line to higher χarm values, indicating higher content of sd grains. figure 5. κ(t) conducted in the air with heating curves (red) and cooling curves (blue). (a, b) typical diagrams for most samples of nottinghambukta, characteristic also of the north stream and the glacier river. (c, d) partial κ(t) analysis for the nb11 sample. (e, f) typical diagrams for the south stream, characteristic also of the outside part of the bay. (g, h) examples of untypical diagrams from the south stream.in thegraphsin theright column (b,d, f,h)theheating curvesareshown withenlargedscaleson they axes,providing moredetail. 6 m. gwizdała et al. comparing both plots (fig. 8), we observe two grain-size trends in χarm versus χlf and only one in χarm versus mrs. it could be the influence of paramagnetic minerals which contribute to low-field susceptibility but not to saturation remanence. additionally, we see that most sediments from the north stream are clustered in one group, while those figure 6. example of hysteresis loops for a sample (a, b) with and (c, d) without pyrrhotite. the graphs on the right (b, d) display loops after paramagnetic correction. figure 7. day-dunlop graph showing the hysteresis magnetization ratio (mrs/ms) versus coercivity ratio (hcr/hc) (day et al. 1977; dunlop 2002a, b). dotted line represents theoretically calculated mixing curveofsingle-domainwith superparamagnetic grains(sd + 10 nm sp). dashed curves represent different mixing curves of single–domain and multi–domain particles (sd + md). figure 8. plots of (a) χarm versus χlf (king et al. 1982) and (b) anhysteretic magnetic susceptibility versus saturation magnetization (mrs). polar research 7 from the south stream form a second group. the samples from nottinghambukta and the glacier river are spread in between. the first group contains material with heterogeneous magnetic properties, whereas the second group exhibits similar and more homogeneous magnetic properties. the geological setting of the studied area suggests that this is probably the result of different parent rocks. along the south stream, the parent rock is of volcaniclastic origin. in contrast, material transported by the north stream mainly are delivered from metamorphosed sedimentary rocks, which results in a more heterogeneous composition and magnetic properties. sediments from the glacier river have a mixture of both and flow into nottinghambukta. the farther from the estuary, the more homogeneous the sediments. conclusions this study demonstrates the novel approach of applying the magnetic method to the analysis of a glacier environment. the magnetic method enables us to distinguish two sets of deposited materials which differ by magnetic mineralogy. the first set consists of a mixture of pyrrhotite and magnetite with predominantly finer grains of sd structure. the second set contains magnetite with larger grains of md structure. this division allows us to ascribe different parent rock to each set: metamorphosed sedimentary rocks from the northern edge of the glacier to the first set and metamorphosed volcaniclastic rocks from the southern edge to the second set. heterogeneous χlf distribution along both streams, the river and the bay, independent of the magnetic composition, suggests that various χlf values could be caused by changes in concentrations of magnetic minerals due to some inhomogeneity of the parent rock, including another – unknown – source of the investigated material. on the other hand, variations in the speed of glacier melting might be responsible for differentiated sorting of the material. the presented study poses new questions to be addressed in the future. acknowledgements the authors would like to thank tomasz gonet for assistance in the collection of samples. the authors are grateful to pedro silva, simo spassov and an anonymous reviewer for their helpful comments and suggestions to the manuscript. disclosure statement no potential conflict of interest was reported by the authors. funding this work was partially financed by funds from the leading national research centre, received by the centre for polar studies for the period 2014-18, and also supported by the polish ministry of science and higher education under statutory activities no. 3841/e-41/s/2015. references birkenmajer k. 1990. geology of the hornsund area, spitsbergen. geological map 1:75000, with explanations. katowice: polish academy of sciences, committee on polar research, and silesian university. blott s.j. & pye k. 2001. gradistat: a grain size distribution and statistics package for the analysis of unconsolidated sediments. earth surface processes and landforms 26, 1237–1248. clark d.a. 1984. hysteresis properties of size dispersed monoclinic pyrrhotite grains. geophysical research letters 11, 173-176. crouzet c., stang h., appel e., schill e. & gautam p. 2001. detailed analysis of successive ptrms carried by pyrrhotite in himalayan metacarbonates: an example from hidden valley, central nepal. geophysical journal international 146, 607–618. czerny j., kieres a., manecki m. & rajchel j. 1993. geological map of sw part of wedel jarlsberg land, spitsbergen 1:25 000. kraków: institute of geology and mineral deposits. day r., fuller m. & schmidt v.a. 1977. hysteresis properties of titanomagnetites: grain-size and compositional dependence. physics of the earth and planetary interiors 13, 260–267. dunlop d.j. 2002a. theory and application of the day plot (mrs/ms versus hcr/hc) 1. theoretical curves and tests using titanomagnetite data. journal of geophysical research—solid earth 107, article no. 2056, doi: 10.1029/2001jb000486. dunlop d.j. 2002b. theory and application of the day plot (mrs/ms versus hcr/hc) 2. application to data for rocks, sediments, and soils. journal of geophysical research—solid earth 107, article no. 2057, doi: 10.1029/2001jb000487. dunlop d.j. & özdemir ö. 1997. rock magnetism: fundamentals and frontiers. cambridge: cambridge university press. evans m.e. & heller f. 2003. environmental magnetism: principles and applications of enviromagnetics. san diego: academic press. folk r.l. & ward w.c. 1957. brazos river bar: a study in the significance of grain-size parameters. journal of sedimentary petrology 27, 3–26. giżejewski j. 1986. interand subtidal sedimentation in the nottingham bay, south spitsbergen. acta geologica polonica 36, 347–355. hagen j.o. & lefauconnier b. 1995. reconstructed runoff from the high arctic basin bayelva based on massbalance measurements. nordic hydrology 26, 285–296. hatfield r.g., reyes a.v., stoner j.s., carlson a.e., beard b.l., winsor k. & welke b. 2016. interglacial responses of the southern greenland ice sheet over the last 430,000 years determined using particle-size specific magnetic and isotopic tracers. earth and planetary science letters 454, 225–236. 8 m. gwizdała et al. https://doi.org/10.1029/2001jb000486 https://doi.org/10.1029/2001jb000486 https://doi.org/10.1029/2001jb000487 https://doi.org/10.1029/2001jb000487 hirt a.m., lanci l. & koinig k. 2003. mineral magnetic record of holocene environmental changes in sägistalsee, switzerland. journal of paleolimnology 30, 321–331. holland m.m. & bitz c.m. 2003. polar amplification of climate change in coupled models. climate dynamics 21, 221–232. hopkinson j. 1890. magnetic properties of alloys of nickel and iron. proceedings of the royal society of london 48, 292–295. ignatiuk d., piechota a.m., ciepły m. & luks b. 2014. changes of altitudinal zones of werenskioldbreen and hansbreen in period 1990-2008, svalbard. aip conference proceedings 1618, 275–280. kieres a. & piestrzynski a. 1992. ore-mineralization of the hecla hoek succession (precambrian) around werenskioldbreen, south spitsbergen. studia geologica polonica 98, 115–151. king j.w., banerjee s.k., marvin j.a. & özdemir ö. 1982. a comparison of different magnetic methods for determining the relative grain size of magnetite in natural materials: some results from lake sediments. earth and planetary science letters 59, 404–419. kosiba a. 1960. some results of glaciological investigations in sw-spitsbergen carried out during the polish i.g.y. spitsbergen expedition in 1957, 1958 and 1959. zeszyty naukowe uniwersytetu wrocławskiego b4. wrocław: university of wrocław. kowalska a. & sroka w. 2008. sedimentary environment of the nottinghambukta delta, sw spitsbergen. polish polar research 29, 245–259. kwok r., cunningham g.f., wensnahan m., rigor i., zwally h.j. & yi d. 2009. thinning and volume loss of the arctic ocean sea ice cover: 2003-2008. journal of geophysical research—oceans 114, c07005, doi: 10.1029/2009jc005312. lanci l. & delmonte b. 2013. magnetic properties of aerosol dust in peripheral and inner antarctic ice cores as a proxy for dust provenance. global and planetary change 110, 414–419. lanci l., hirt a.m., lowrie w., lotter a.f., lemke g. & sturm m. 1999. mineral magnetic record of late quaternary climatic changes in a high alpine lake. earth and planetary science letters 170, 49–59. lanci l., kent d.v., biscaye p.e. & bory a. 2001. isothermal remanent magnetization of greenland ice: preliminary results. geophysical research letters 28, 1639–1642. liu q., roberts a.p., larrasoana j.c., banerjee s.k., guyodo y., tauxe l. & oldfield f. 2012. environmental magnetism: principles and applications. reviews of geophysics 50, rg4002, doi: 10.1029/ 2012rg000393. majchrowska e., ignatiuk d., jania j., marszałek h. & wąsik m. 2015. seasonal and interannual variability in runoff from the werenskioldbreen catchment, spitsbergen. polish polar research 36, 197–224. miller g.h., alley r.b., brigham-grette j., fitzpatrick j.j., polyak l., serreze m.c. & white j.w.c. 2010. arctic amplification: can the past predict the future? quaternary science reviews 29, 1679–1715. pälli a., moore j.c., jania j., kolondra l. & glowacki p. 2003. the drainage pattern of hansbreen and werenskioldbreen, two polythermal glaciers in svalbard. polar research 22, 355–371. peters c. & dekkers m.j. 2003. selected room temperature magnetic parameters as a function of mineralogy, concentration and grain size. physics and chemistry of the earth 28, 659–667. sagnotti l., macri p., camerlenghi a. & rebesco m. 2001. environmental magnetism of antarctic late pleistocene sediments and interhemispheric correlation of climatic events. earth and planetary science letters 192, 65–80. solomon s., qin d., manning m., chen z., marquis m., averyt k.b., tignor m. & miller h.l. (eds.) 2007. contribution of working group i to the fourth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. stachnik ł., majchrowska e., yde j.c., nawrot a., cichała–kamrowska k., ignatiuk d. & piechota a. 2016. chemical denudation and the role of sulfide oxidation at werenskioldbreen, svalbard. journal of hydrology 538, 177–193. stocker t.f., qin d., plattner g.k., tignor m., allen s.k., boschung j., nauels a., xia y., bex v. & midgley p.m. (eds.) 2013. climate change 2013. the physical science basis. contribution of working group i to the fifth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. thienpont j.r., korosi j.b., cheng e.s., deasley k., pisaric m.f.j. & smol j.p. 2015. recent climate warming favours more specialized cladoceran taxa in western canadian arctic lakes. journal of biogeography 42, 1553–1565. polar research 9 https://doi.org/10.1029/2009jc005312 https://doi.org/10.1029/2009jc005312 https://doi.org/10.1029/2012rg000393 https://doi.org/10.1029/2012rg000393 abstract introduction study area methods sampling characterization of study material magnetic methods results and discussion magnetic analyses conclusions acknowledgements disclosure statement funding references doi:10.3402/polar.v34.25629 r e s e a r c h / r e v i e w a r t i c l e is ornithogenic fertilization important for collembolan communities in arctic terrestrial ecosystems? katarzyna zmudczyńska-skarbek,1 adrian zwolicki,1 peter convey,2 mateusz barcikowski1 & lech stempniewicz1 1 department of vertebrate ecology and zoology, university of gdańsk, wita stwosza 59, pl-80-308 gdańsk, poland 2 british antarctic survey, natural environmental research council, high cross, madingley road, cambridge cb3 0et, uk keywords springtails; seabirds; ornithogenic tundra; spitsbergen; bear island; multivariate analyses. correspondence katarzyna zmudczyńska-skarbek, department of vertebrate ecology and zoology, university of gdańsk, wita stwosza 59, pl-80-308, gdańsk, poland. e-mail: biozmud@ug.gda.pl abstract in the arctic, areas close to seabird colonies are often characterized by exceptionally rich vegetation communities linked with the high nutrient subsidies transported by seabirds from the marine environment to the land. these areas also support soil invertebrate communities of which springtails (collembola) often represent the most abundant and diverse group. our study focused on springtail community composition in the vicinity of seabird (little auk, great skua and glaucous gull) nesting areas in different parts of svalbard (magdalenefjorden, isfjorden and bjørnøya), and on their comparison with adjacent areas not impacted by seabirds. out of a total of 35 springtail species recorded, seven were found only within the ornithogenically influenced sites. although geographical location was the strongest factor differentiating these springtail communities, ornithogenic influence was also significant regardless of the location. when each location was considered separately, seabirds were responsible for a relatively small but strongly significant proportion (8.6, 5.2 and 3.9%, respectively, for each site) of total springtail community variability. species whose occurrence was positively correlated with seabird presence were folsomia coeruleogrisea, friesea quinquespinosa, lepidocyrtus lignorum and oligaphorura groenlandica near magdalenefjorden, arrhopalites principalis, folsomia bisetosella and protaphorura macfadyeni in isfjorden, and folsomia quadrioculata on bjørnøya. to access the supplementary material for this article, please see supplementary files under article tools online. arctic terrestrial ecosystems are generally regarded as being relatively simple, species-poor and characterized by short food chains. very strong seasonality, a short, cold growing season, nutrient deficiency, permafrost, scant liquid water and regular freeze�thaw cycles strongly restrict primary and secondary production (ims & ehrich 2013). low energy and limited snowand ice-free land, the relatively young age of contemporary arctic terrestrial ecosystems, and spatial isolation contribute to generally low species diversity, especially in the case of higher plants and vertebrate herbivores and predators (payer et al. 2013). however, spatial heterogeneity in, for instance, temperature, precipitation, wind exposure, hydrology, geomorphology (elevation), proximity to coastlines and soil chemistry create environmental gradients and complex mosaics of habitats that may support considerable diversification of communities of smaller organisms such as invertebrates (hertzberg et al. 2000; sinclair & sjursen 2001; ims & ehrich 2013). even very small patches of suitable favourable habitats surrounded by a hostile environment, such as individual carex tussocks embedded in cyanobacteria-covered ground (hertzberg et al. 1994; hertzberg et al. 2000; ims et al. 2004), azorella cushion plants on sub-antarctic marion island (hugo et al. 2004), polar research 2015. # 2015 k. zmudczyńska-skarbek et al. this is an open access article distributed under the terms of the creative commons attributionnoncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/25629/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/25629/0 http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 cryoconite holes (de smet & van rompu 1994) and glacier mice (coulson & midgley 2012), may provide viable habitats for these animals. most of the arctic invertebrate fauna inhabit soil and soil surface environments, and these organisms can develop much higher abundance, species diversity and food web complexity in suitable habitats than any other non-microbial eukaryotes on the land (hodkinson & coulson 2004; hodkinson 2013; coulson et al. 2014). springtails (collembola) are often the most abundant and diverse group (bengston et al. 1974; uvarov & byzova 1995; birkemoe & leinaas 2000). although it is widely assumed that springtails play essential roles in many key polar ecosystem processes, such as decomposition, energy flow and nutrient cycling, mainly through grazing on microorganisms and physical alteration of soil and litter (hopkin 1997; rusek 1998; bardgett & chan 1999; filser 2002), detailed knowledge about the distribution and autecology of most species is lacking (hogg et al. 2006; hodkinson 2013). studies of polar (both arctic and antarctic) collembolan and other invertebrate assemblages over multiple spatial scales have revealed strong heterogeneity in their distribution and abundance. between different geographical regions this may be driven by environmental conditions such as temperature and moisture associated with climate (babenko 2000; bokhorst et al. 2008), as well as historical dispersal and colonization processes (ávila-jiménez & coulson 2011). in the typical mosaic of high arctic terrestrial habitats, microtopography and habitat moisture, temperature and habitat quality parameters such as physico-chemical properties of substrate, decomposition rate and food availability affect the invertebrate communities at the scale of meters (usher & booth 1986; dollery et al. 2006; caruso & bargagli 2007; zmudczyńska et al. 2012; hodkinson 2013). the size and isolation of habitat patches and especially their plant species composition may further contribute to the variability of springtail assemblages (hertzberg et al. 1994; hertzberg et al. 2000; ims et al. 2004). at the scale of centimetres, invertebrates may be associated with particular plant species and/or local environmental conditions formed beneath them (coulson et al. 1993; block & convey 1995; coulson et al. 2003; gwiazdowicz & coulson 2011). finally, even within relatively homogeneous habitat, clustering of invertebrates may be also explained by inter-species relationships (usher & booth 1986; caruso et al. 2007; caruso et al. 2013), pheromone-induced aggregation (leinaas 1983; usher & booth 1984, 1986; benoit et al. 2009), and past stochastic events causing uneven mortality or other demographic phenomena (coulson et al. 2000; chown & convey 2007). within the patchy high arctic terrestrial ecosystem, particularly favourable habitats for many organisms are found in the vicinity of seabird nesting sites, especially the larger bird colonies which may consist of several hundred thousand individuals (lindeboom 1984; odasz 1994; stempniewicz et al. 2007). these areas are fertilized by nutrients transported by the birds from the marine environment and deposited on land in the form of guano, feathers, egg shells and carcasses (bokhorst et al. 2007; zwolicki et al. 2013). the ornithogenically subsidized areas support exceptionally lush vegetation (zmudczyńska et al. 2008; zmudczyńska-skarbek et al. 2013) including specific plant communities (eurola & hakala 1977; elvebakk 1994; zmudczyńska et al. 2009), and populations of herbivores, predators and scavengers (croll et al. 2005; jakubas et al. 2008; kolb et al. 2011). collembola feeding on fresh and dead organic matter may specifically graze on or accidentally ingest fungi, algae, bacteria and other microbiota (hopkin 1997; rusek 1998; worland & lukešová 2000) and may also attain very high population densities in ornithogenic substrates around seabird colonies (coulson et al. 2014). while the contribution of collembolans to decomposition in the arctic terrestrial ecosystem is thought to be vital, relatively little attention has been given to their role in ornithogenically influenced habitats (see mulder et al. 2011). byzova et al. (1995) reported extremely high density and biomass of springtails in the vicinity of a little auk (alle alle) colony in hornsund (south-west spitsbergen), reaching more than 10 5 ind. and 5 g m �2 , these values being higher than reported either in most non-influenced ecosystems or in nutrient-enriched manure heaps. we have also reported similar values both associated with little auks and below a nearby cliff-nesting colony of brunnich’s guillemots (uria lomvia) and kittiwakes (rissa tridactyla) (zmudczyńska et al. 2012). high springtail density has also been noted from seabird-influenced sites in another west spitsbergen fjord, kongsfjorden (bengston et al. 1974; sømme & birkemoe 1999), and on nordaustlandet, the northern-most island of the svalbard archipelago (fjellberg 1997). sømme & birkemoe (1999) and zmudczyńska et al. (2012) described gradual changes in collembolan community composition with distance from seabird colonies. specific communities have also been described in areas experiencing the most intensive ornithogenic manuring, with few species strongly represented, including megaphorura (formerly onychiurus) arctica, hypogastrura viatica, folsomia quadrioculata and xenylla humicola (hodkinson et al. 1994; uvarov & byzova 1995; fjellberg 1997; sømme & birkemoe 1999; zmudczyńska et al. 2012). is ornithogenic fertilization important for collembolan communities? k. zmudczyńska-skarbek et al. 2 (page number not for citation purpose) citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 most studies to date have focused on single seabird colonies and locations, and addressed basic parameters of springtail community description, such as overall species richness, density and biomass of collembola as a whole, or only focusing on the most abundant species. in a previous study of two seabird colonies at hornsund, we identified significant correlations between springtail density and soil physical and chemical properties, and vegetation biomass (zmudczyńska et al. 2012). factors significantly influencing the springtail community in that study included the cover of green nitrophilous alga prasiola crispa (explaining 11% of the total springtail variability), total plant biomass (9%) and soil conductivity (6%). these factors were all clearly associated with distance from the seabird colonies and guano deposition (see also zwolicki et al. 2013). in the current study, we used multivariate analytical techniques to generate quantitative estimates of, first, the proportion of total variability in the collembola community explained by seabird influence. to our knowledge, this question has not previously been tested, and multivariate (ordination) approaches have rarely been applied in the study of ornithogenic impact on invertebrate assemblages worldwide (but see orgeas et al. 2003; towns et al. 2009; kolb et al. 2012; zmudczyńska et al. 2012). second, this approach will permit the identification of springtail species that are specifically linked with seabirdmediated changes in the environment. we analysed collembolan communities collected over a much wider geographical scale than has been achieved previously, ranging from the relatively small island of bjørnøya (748n), which is the southernmost island of svalbard, to the second largest spitsbergen fjord isfjorden located in the centre and mildest part of the island (788n), to the northern-most west spitsbergen coast close to magdalenefjorden (798n). we obtained samples from six seabird nesting sites and respective control areas. this coverage also enabled us to assess the role of geographical location within the archipelago in explaining variability between the springtail communities found. finally, as other studies have related the occurrence of collembola and vegetation communities/species (hertzberg et al. 1994; coulson et al. 2003; ims et al. 2004), we evaluated the strength of this relationship in the vicinity of seabird colonies. materials and methods study area the study was conducted at three locations within the svalbard archipelago, one on bjørnøya (bear island) and two on spitsbergen (fig. 1). within all sampling plots we identified vascular plant species and visually (using a plot-sized quadrat subdivided into 20 �20 cm units) estimated the individual species and total moss percentage contributions to vegetation cover. bjørnøya (bjo). this is the southernmost island (176 km 2 ) of the archipelago, midway between the norwegian mainland and spitsbergen. three sites in the vicinity of different seabird species nesting areas, together with respective control sites, were sampled. site b-a (74838?n 19803?e) was close to a relatively large colony of the planktivorous little auk situated on a gentle slope on alfredfjellet, exposed to the north and descending to lake ellasjøen. the upper part of the site consisted of vegetation-covered rock debris, while the lower part approaching the lake shore was flat and waterlogged. vegetation cover was complete in both parts of the area. vegetation consisted of vascular plants, mainly salix sp. and saxifragaceae (and equisetum arvense in the waterlogged area), interspersed with compact moss carpets and clumps. site b-ac was the control site for b-a, located on alfredfjellet and parallel to b-a but ca. 500 m from the colony and separated from it by a seasonal stream. similar plant species to site b-a were present, but the total cover of vegetation was around 20% (see above for method of estimation). site b-l (74847?n 18878?e) was located in the north-west, flat part of the island, close to the cliff edge fig. 1 study area locations within the svalbard archipelago. k. zmudczyńska-skarbek et al. is ornithogenic fertilization important for collembolan communities? citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 and to a concentration of nests of the predatory (feeding on fish, large pelagic invertebrates and other seabirds) glaucous gull (larus hyperboreus), with patches of dense vegetation surrounding each nest. vascular plants were usually underlain by a dense moss layer (80% moss cover on average), and were dominated by festuca cf. rubra subsp. arctica (up to 100%), with less than 10% admixture of oxyria digyna, saxifraga caespitosa and draba sp. site b-s (74847?n 18876?e) was located inland from b-l, in close proximity to nests of the predatory (feeding on fish and other seabirds) great skua (stercorarius skua). vegetation was similar to that of b-l, but f. cf. rubra subsp. arctica was less abundant (on average 70% cover), with a generally more species rich herb/shrub flora, and more abundant mosses (90%) present. in addition to the species listed above, salix sp., cerastium sp. and other saxifragaceae were present (up to 80, 20, and b1% cover, respectively). sites b-lc and b-sc were the control sites for b-l and b-s, respectively, and were situated beyond the dense vegetation patches surrounding individual nests, on average 3 m from the relevant nest sites. total vegetation cover values (b-lc: 90%, b-sc: 10%), and especially those of vascular plant species (b-lc: 10%, b-sc: 3%), were lower than those of the respective nest sites. isfjorden (isf). site i-a (78824?n 15834?e) was close to a medium-sized little auk colony in bjørndalen, on the western slope of platåberget. vegetation consisted of a mixed community of mosses (on average 40% cover) and vascular plants (35%), with a considerable proportion of salix polaris (up to 50%, average 25%) and small admixtures of species such as poa alpina var. vivipara, cerastium arcticum, trisetum arvense, o. digyna and saxifragacae. site i-ac was the control site located parallel to i-a but ca. 1 km from the colony. vegetation was similar to that of i-a, but mosses were more abundant (on average 55%) with vascular plants including t. arvense, o. digyna and p. alpina var. vivipara correspondingly lower (20%). magdalenefjorden (mag). the sites m-a1 and m-a2 (79852?n 10870?e) were situated on the talus slope of aasefjellet, exposed to the west and descending to the open sea, adjacent to very large little auk colonies. the vascular plant layer was underlain by dense moss, giving up to 95% cover, and mostly consisted of c. arcticum, p. alpina var. vivipara and c. groenlandica. site m-ac, the control site for both m-a1 and m-a2, was located on aasefjellet (ca. 700 m and 500 m from m-a1 and m-a2, respectively), facing north and descending to hamburgbukta. boulders that were not overgrown with vegetation composed a significant proportion of this area (up to 60% in some plots), with the remaining area predominantly covered by mosses. sampling protocol the study was conducted in the summer months of july and august, during expeditions to bjørnøya (2008), magdalenefjorden (2009) and isfjorden (2010). around little auk colonies, samples were collected along line transects down the slopes below the seabird colonies (sites: b-a, i-a, m-a1 and m-a2), and in their respective control sites (b-ac, i-ac, and m-ac). each transect consisted of 5�9 plots (160 �160 cm each) that were located from the transect’s starting point (plot 1) as follows: plot 2 (6 m), 3 (15 m), 4 (29 m), 5 (49 m), 6 (79 m), 7 (125 m), 8 (193 m) and 9 (296 m), as described by zmudczynska et al. (2012). due to practical logistic limitations, on transects b-a and b-ac every second plot was sampled (plots 1, 3, 5, 7 and 9). we collected three soil cores (together with vegetation cover, see below) from three sites along the same diagonal of each sampling plot (from the centre and the two corners of each square) (table 1). table 1 study areas and sampling pattern. area/locality seabird species colony size/type site n plots n samples bjørnøya 97 117 ellasjøen (alfredfjellet) little auk large b-a 5 15 control b-ac 5 15 north-west bjørnøya glaucous gull individual nests b-l 10 10 control b-lc 5 5 north-west bjørnøya great skua individual nests b-s 48 48 control b-sc 24 24 isfjorden 18 54 bjørndalen (platåberget) little auk medium-sized i-a 9 27 control i-ac 9 27 magdalenefjorden 25 75 hamburgbukta (aasefjellet) little auk very large m-a1 9 27 little auk very large m-a2 9 27 control m-ac 7 21 is ornithogenic fertilization important for collembolan communities? k. zmudczyńska-skarbek et al. 4 (page number not for citation purpose) citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 in the cases of great skua and glaucous gull nesting sites located on flat ground, three plots (100 �100 cm each) were sampled in the vicinity of each nest: (plot 1) with a nest situated in the centre, (2) adjoining plot 1, still within the patch of dense vegetation surrounding the nest (both plots included in sites b-l and b-s), and (3) beyond the boundary of the compact vegetation patches, 3 m on average from the nest (sites b-lc and b-sc, respectively). we collected one soil core from the centre of each plot, except in plot 1 where the sample was taken adjacent to the nest (table 1). nests containing eggs or chicks were not sampled. sampled nests had been recently occupied as evidenced by the presence of down and other nest material, and food scraps, but we cannot be fully certain that they had been occupied in that year’s summer season. samples were taken with a cylindrical probe (diameter 6 cm) from the soil surface (mainly organic) layer, and included the vegetation covering the area and the underlying soil to a depth of ca. 5 cm. each sample was sealed in a plastic container and, within a few hours, returned to the laboratory where it was subsequently placed for 48 h in a modified tullgren apparatus illuminated with 60w bulbs (barton 1995). extracted springtails were preserved in 96% ethanol and identified to species level following fjellberg (1998, 2007). we calculated frequencies of occurrence (%) and densities of particular species (number of individuals per m 2 ). for cores obtained from the 160 �160 cm plots, total springtail species counts for each plot (i.e., the sum of the three samples obtained) were analysed. statistical analyses to test for differences in the springtail species richness between the study areas the non-parametric mann-whitney u-test was used on account of the non-normal distributions of data and a relatively low number of sampling plots per group tested. data were processed using statistica 10.0 (statsoft, inc. 2011). numerical ordination methods were used to describe total (qualitative and quantitative) variability of springtail communities and vegetation: (1) independently of any environmental influence (unimodal indirect gradient analysis: detrended correspondence analysis [dca]), to describe the general pattern of variability in the studied community; and (2) in relation to environmental variables (unimodal direct gradient analysis: canonical correspondence analysis [cca]). two nominal environmental factors were tested: area, determining the geographical location (bjo, isf or mag), and seabird, representing the presence (seabird) or absence (control) of a seabird colony in the vicinity of sampling sites. all species data were log-transformed to normalize their distributions. after cca, a monte carlo permutation test was performed (with 499 permutations) to identify which of the factors significantly influenced the model. to calculate the factors’ unique contribution to explaining variability in the springtail species composition we used variation partitioning test (ter braak & šmilauer 2012). to provide more accurate estimation of variation explained with canonical (cca) analyses, we adjusted the variation value using the number of degrees of freedom as suggested by peresneto et al. (2006). each time the results of constrained ordination were compared with those of unconstrained ordination (% variability explained by an environmental factor was divided by % variability explained by one (in the case of seabird) or two (area) axes of the unconstrained analysis). thus we obtained the efficiency of the environmental factor(s) (%) in explaining the total variability present in the data (ter braak & šmilauer 2012). in order to relate ordinations based on springtail community composition with those of vegetation composition, we used co-correspondence analysis (coca; ter braak & šmilauer 2012). to explore significant relationships between individual springtail species and the environmental factor seabird we employed t-value biplots (van dobben circles) that approximated the t-values of the regression coefficients of a weighted multiple regression (ter braak & šmilauer 2012). data were processed using canoco 5.0 software (ter braak & šmilauer 2012). results within the total of 140 plots (246 samples) studied, we recorded 35 springtail species: 17 on bjørnøya, 21 in isfjorden and 30 in magdalenefjorden (table 2, supplementary table s1). the average numbers of species were similar across seabird and control sites in all plots taken together and in each location, except for magdalenefjorden where it was higher in m-a1 than in m-ac (mannwhitney test, u �3.00, p �0.003). however, in total, more species occurred within seabird sites versus their respective control sites in the case of three little auk colonies: i-a (20) versus i-ac (18), and m-a1 (18) and ma2 (23) versus m-ac (14); and in the case of the great skua nesting area: b-s (12) versus b-sc (eight). on bjørnøya, the same number of species was noted close to the little auk colony and within its control site (seven in both b-a and b-ac), while the number was lower in b-l (seven) than in b-lc (nine) adjacent to glaucous gull nests. seven species occurred only within seabird sites: arrhopalites principalis (b-a, i-a, m-a1), ceratophysella longispina (ma2), c. succinea (b-s, m-a2), desoria neglecta (m-a1), mesaphorura macrochaeta (i-a), pseudanuphorus alticola k. zmudczyńska-skarbek et al. is ornithogenic fertilization important for collembolan communities? citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/25629/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/25629/0 http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 (m-a2) and sphaeridia pumilis (m-a1) (supplementary table s1). two species were recorded only on control sites: agrenia bidenticulata (m-ac) and thalassaphorura duplopunctata (b-ac) (supplementary table s1). almost 20% of variability in springtail species composition was explained by two hypothetical gradients (unconstrained ordination axes), with 12.1% explained by axis 1 and 7.7% by axis 2 (dca, gradient length �4.00 sd; table 3, fig. 2a). cca (constrained ordination) revealed that the area factor (bjo, isf, mag) was responsible for 13.4% of the total collembolan variability, while the seabird factor (seabird, control) accounted for 2.1% (fig. 3). these factors therefore contributed 67.7% (area) and 17.4% (seabird) of the variation explained by the model. the area and seabird factors were independent of each other and did not share the explained variation (variation partitioning test, f �8.8, p �0.002). the areas studied were distinct with respect to their vegetation composition. the plots from different areas formed distinct groups in the unconstrained ordination (dca) space based on plant species and moss abundances recorded (fig. 2b). the area factor explained 19.3% of the total vegetation variability, equating to 83.0% of the variation described with dca (axis 1: 15.3%, axis 2: 8.0%, gradient length �2.58 sd). the variabilities of springtail and vegetation communities were not significantly correlated (coca, p�0.05). because of the clear differentiation of the three localities (both with respect to collembolan and vegetation diversity, as well as in terms of geographical distance), in subsequent analyses each area was treated separately. neither springtail nor vegetation variability were significantly co-correlated within any of the individual areas studied (coca, p�0.05). on bjørnøya, the seabird factor was responsible for 3.9% of the total springtail variability, constituting 30.7% of the variability identified by the theoretical unconstrained analysis (table 3). of the collembolan species best fitted to the first cca axis (equivalent to the seabird factor; the species shown in fig. 4a), folsomia quadrioculata was significantly positively associated with this explanatory variable while four other species*desoria tshernovi, hypogastrura viatica, tetracanthella arctica and thalassaphorura duplopunctata*were associated negatively (species selected using van dobben circles; table 4). in isfjorden, the proportion of variation in collembolan community composition that was influenced by seabird presence was 5.2%, equating to 24.6% of the available variation (table 3). three species were positively related to seabird impact*arrhopalites principalis, folsomia bisetosella and protaphorura macfadyeni*and two species related to it negatively lepidocyrtus lignorum and parisotoma notabilis: (fig. 4b, table 4). in magdalenefjorden, seabird influence accounted for 8.6% of the total springtail variability, or 44.8% of the total available (table 3). here, four species reacted positively to seabird impact: folsomia coeruleogrisea, friesea quinquespinosa, oligaphorura groenlandica and l. lignorum (which responded negatively in isfjorden). among six species that were negatively associated with table 2 number of species recorded in each site and area of the current study, and summed up for the seabird and control sites. area bjørnøya isfjorden magdalenefjorden site b-a b-ac b-l b-lc b-s b-sc i-a i-ac m-a1 m-a2 m-ac no. of species per site 7 7 7 9 12 8 20 18 18 23 14 no. of species found only in seabird 3 1 5 3 6 11 no. of species found only in control 3 3 1 1 2 no. of species common for seabird and control 4 6 7 17 12 no. of species per area 17 21 30 table 3 percent of variability in vegetation and collembolan communities explained by hypothetical gradients (axes 1 and 2; detrended correspondence analysis [dca]) and environmental factors (area and seabird; canonical correspondence analysis [cca]), with the explaining efficiency of the factors (factors’ contribution to the variation explained by the axes). variability explained (%) area dca axis 1 dca axis 2 environmental factor (cca) f p efficiency (%) vegetation all areas 15.3 8.0 area: 19.3 17.7 0.002 83.0 collembola all areas 12.1 7.7 area: 13.4 10.8 0.002 67.7 seabird: 2.1 3.7 0.002 17.4 bjørnøya 12.7 � seabird: 3.9 4.4 0.002 30.7 isfjorden 21.1 � seabird: 5.2 1.9 0.008 24.6 magdalenefjorden 19.2 � seabird: 8.6 4.4 0.002 44.8 is ornithogenic fertilization important for collembolan communities? k. zmudczyńska-skarbek et al. 6 (page number not for citation purpose) citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 http://www.polarresearch.net/index.php/polar/rt/suppfiles/25629/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/25629/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/25629/0 http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 seabirds in magdalenefjorden was f. quadrioculata determined as positive in bjørnøya (fig. 4c, table 4). the relationships with seabird influence were still present for nine species (five positive and four negative) when all the areas were analysed together (table 4). discussion although the key role of colonial seabirds in the enrichment of the otherwise poor arctic terrestrial ecosystem is relatively well recognized, data on soil invertebrate assemblages inhabiting ornithogenically modified areas are still sporadic. the six previous studies that we are aware of listed species occurring close to rich seabird nesting sites along with, at most, data on overall collembola density and biomass (bengston et al. 1974; hodkinson et al. 1994; byzova et al. 1995; uvarov & byzova 1995; fjellberg 1997; sømme & birkemoe 1999). our previous studies at hornsund have identified some factors significantly correlated with springtail abundance and community composition, including the amount of guano deposited and soil and vegetation parameters that are closely associated with bird colony impact (zmudczyńska et al. 2012; zwolicki et al. 2013). the present study is the first to attempt to estimate quantitatively the proportion of variation in arctic collembola communities explained by seabird influence, and one of very few that has addressed this question worldwide (kolb et al. 2011). almost 20% of total variability of springtail species composition in our data set (comprising 35 species recorded in 140 sampling plots from different habitats and geographical regions of the svalbard archipelago) was explained by two hypothetical environmental gradients (unconstrained dca axes). the most important factor accounting for this variation (68%) appeared to be related to geographical location. we sampled three widely separated parts of the archipelago. at this regionally large spatial scale the sampling areas differed in exposure to the marine environment and, in particular, to the influence of ocean currents and temperatures of the water masses predominating at each (loeng & drinkwater 2007; saskaug et al. 2009). for instance, with a mean july temperature of 5.98c in 1961�1990 (eklima 2014), isfjorden is the warmest part of svalbard, mostly due to the large inflow of warm atlantic water. bjørnøya, surrounded by cold arctic water but also in close proximity to atlantic water masses, experiences large amounts of fog and high winds (summerhayes & elton 1923; saskaug et al. 2009), higher precipitation (30 mm in july compared to 18 mm in isfjorden) and lower summer temperature (4.48c in july), while being the mildest throughout winter ( �8.18c in january). the key role of geographical factors underlying collembola distribution has been emphasized by caruso fig. 2 detrended correspondence analysis (dca) ordination of plots classified with respect to (a) springtail species composition and (b) vegetation composition of the different study areas. k. zmudczyńska-skarbek et al. is ornithogenic fertilization important for collembolan communities? citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 & bargagli (2007) and babenko (2009) in studies sampling different locations across latitudinal gradients in northern victoria land (antarctica) and on the western taimyr peninsula (russian arctic), respectively. although these studies did not assess the total species richness in the study areas, both noted that some species did not occur at all localities along each transect. caruso & bargagli (2007) demonstrated that variability in springtail species richness between their study sites was the same whether considering distance scales of 10 km or 100 m. dca ordination of plots in our study revealed a similar pattern, with some samples from bjørnøya being more similar to those from other svalbard areas than others within the island itself (fig. 2a). furthermore, although the southernmost and also the most extensively sampled location (117 samples, in comparison with 54 from isfjorden and 75 from magdalenefjorden), bjørnøya hosted the lowest number of springtail species (17 as compared with 21 and 30, respectively). we therefore conclude that the inter-area distinctions identified from our data do not represent a latitudinal gradient but, rather, large-scale variability resulting from a range of factors, including local climate, historical dispersal and colonization processes (babenko 2000; bokhorst et al. 2008; ávila-jiménez & coulson 2011; hodkinson 2013). similarly, geographical factors may underlie the distinctions identified between the study areas in terms of vegetation community composition, accounting for 83% of the variation described by dca. in this case, the length of the gradient representing beta-diversity (ter braak & šmilauer 2012) was lower (2.6 sd) than that calculated for collembola (4 sd) while, as noted above, there was no correlation apparent between the vegetation and collembolan communities. however, the survey scales also differed between these two groups, with springtails being extracted from cores of 6 cm diameter, and vegetation composition documented in complete 160 �160 cm or 100 �100 cm plots, areas that are likely to host multiple fig. 3 canonical correspondence analysis (cca) ordination of springtail species (triangles) with respect to the influence of different areas*bjørnøya (bjo), isfjorden (isf) and magdalenefjorden (mag)*and the presence (seabird) and absence (control) of a seabird colony in the vicinity of a sampling site (diamonds). is ornithogenic fertilization important for collembolan communities? k. zmudczyńska-skarbek et al. 8 (page number not for citation purpose) citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 invertebrate microhabitats (usher & booth 1986; caruso & bargagli 2007; hodkinson 2013). irrespective of the scale considered and the geographical influence, our analyses demonstrate that seabirds exerted significant influence on springtail communities in svalbard. seven of the 35 springtail species recorded were present only in the seabird-influenced sites. collembolan community variability was explained by the seabird factor to a greater extent when each area was considered separately than when data from all the areas were combined (table 3), probably a consequence of the community composition differing in detail between the areas. hence, the springtail assemblage recorded within any one area contained one to four species that were positively correlated with the seabird influence, without the same relationship being identified in the other study areas. for instance, folsomia quadrioculata is recognized as a widely distributed species in the arctic and has been considered to have no clear habitat preferences (fjellberg 1994), although it has also been recorded as notably abundant below bird cliffs (fjellberg 1997; sømme & birkemoe 1999; zmudczyńska et al. 2012). in the current study, this species’ presence was significantly correlated with seabird influence on bjørnøya, but negatively correlated in magdalenefjorden. other species positively associated with seabird influence in analyses of the remaining areas are known for their occurrence in rich ornithogenic sites, and include both species characteristic of wet (e.g., oligaphorura groenlandica) and dry (e.g., lepidocyrtus lignorum) habitats (fjellberg 1994). those species for which significant responses were not necessarily found in ordinations (likely due to small sample sizes), but were found exclusively within seabird-influenced sites, were also typical of eutrophic and usually wet or moist habitats. two such fig. 4 canonical correspondence analysis (cca) ordinations of 10 best-fitted species with respect to the seabird factor (axis 1) in each area. pie slices based on species percentage occurrence within seabird (black) and control (white) sites. boldface indicates species that significantly and positively react to the seabird explanatory variable (on the basis of t-value biplot). k. zmudczyńska-skarbek et al. is ornithogenic fertilization important for collembolan communities? citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 species*sphaeridia pumilis and pseudanuphorus alticola (both recorded from magdalenefjorden)*have previously been recorded only sporadically from svalbard, the former from kolhamna/kongsfjorden (fjellberg 1994) and russebukta/edgeøya (www.artsobservasjoner.no), and the latter from jan mayen (fjellberg 1994), kinnvika/ nordaustlandet (coulson et al. 2011) and barentsburg/ isfjorden (coulson et al. 2013). notably, some species responding negatively in the current study to the seabird factor (e.g., parisotoma notabilis, tetracanthella arctica) or totally absent from the seabird areas (thalassaphorura duplopunctata) have previously been noted in rich (also ornithogenic), both wet and dry sites (fjellberg 1998, 2007). this emphasizes the importance of conducting analyses of the entire springtail community inhabiting an area rather than focusing on individual species that may react differently to a given factor when additional environmental conditions are considered. a priori, the most obvious potential link by which seabird influence might interact with collembolan communities would appear to be via the soil and vegetation developing on rich ornithogenic substrates around nesting sites, both of which clearly differ from those of nonfertilized areas (eurola & hakala 1977; zwolicki et al. 2013). we have shown previously that the density of all springtails as well as that of the locally predominating species (f. quadrioculata and h. viatica) were significantly though moderately correlated (correlation coefficients ranging from 0.2 to 0.5) with individual chemical and physical soil properties (zmudczyńska et al. 2012). each of these factors was strongly correlated to seabird guano deposition (coefficients of 0.6 to 0.9, zwolicki et al. 2013), but only soil conductivity significantly influenced the collembola composition. such evidence supports springtails not being directly dependent on a single factor but rather influenced by a range of complex environmental factors. as some studies have identified significantly distinct microarthropod assemblages associated with particular plant species/communities and/or the specific properties of soil forming beneath them (e.g. coulson et al. 2003), we hypothesized that a strong relationship would exist between springtails and vegetation composition in the studied areas. however, no such correlation was apparent in our data, even when each study area was analysed separately. plants are potentially available for springtails as food (typically during decay rather than through active grazing), as well as contributing to the modification of habitat properties such as soil moisture and temperature. however, seabirds may alter the quality and quantity of several different food resources, including algae, fungi and other microorganisms (matuła et al. 2007; wright et al. 2010). for instance, in hornsund a green nitrophilous alga species, prasiola crispa, growing abundantly below the seabird colonies was significantly associated with the collembolan community (zmudczyńska et al. 2012) and might therefore be an important diet component there. moreover, seabirds may affect distribution and abundance of different invertebrate groups, such as mites, beetles or dipteran larvae that may compete for the resources and/or prey on collembolans (bengston et al. 1974; caruso et al. 2013; basset et al. 2014). unfortunately, as is often the case in studies of polar terrestrial ecosystems (worland & lukešová 2000; hogg et al. 2006), detailed autecological information (including diet studies) of most of the springtail species reported here is lacking. the multivariate analyses applied here provided clear evidence of the significant role that seabird influence plays for these soil invertebrate communities in the arctic. while the explanatory power of the seabird enrichment was relatively low, the ornithogenic effect was significant both at the scale of the entire svalbard archipelago and within each specific geographical location. other factors, such as small-scale habitat conditions (enhanced by the typical patchiness of tundra habitats [e.g., hertzberg et al. 1994; ims et al. 2004]), population density fluctuations from year to year (sømme & birkemoe 1999), and natural tendency for aggregation (leinaas 1983; usher & booth 1984, 1986; benoit et al. 2009) contribute additional variation to the collembola community. given that springtails provide key ecosystem services contributing to organic matter decomposition, energy flow and nutrient table 4 significant positive (�) and negative ( �) response of collembola species for the seabird factor, chosen on the basis of t-value biplots made separately for each area: bjørnøya (bjo), isfjorden (isf), magdalenefjorden (mag) and all the areas together (all). species bjo isf mag all agrenia bidenticulata � � anurida polaris � arrhopalites principalis � desoria tshernovi � folsomia bisetosella � � folsomia coeruleogrisea � � folsomia quadrioculata � � friesea quinquespinosa � � hypogastrura viatica � isotoma anglicana � lepidocyrtus lignorum � � oligaphorura groenlandica � � parisotoma notabilis � � protaphorura macfadyeni � sminthurides malmgreni � � sphaeridia pumilis � tetracanthella arctica � � thalassaphorura duplopunctata � xenylla humicola � is ornithogenic fertilization important for collembolan communities? k. zmudczyńska-skarbek et al. 10 (page number not for citation purpose) citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 http://www.artsobservasjoner.no http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 cycling, and considering that these processes, together with the invertebrate communities and colonial seabirds, are expected to be strongly influenced by predicted climate warming, especially in the polar regions (callaghan et al. 2005; hodkinson 2013; ims & ehrich 2013), further studies of collembola distribution, abundance and functional ecology are required, with these being planned over appropriate spatial and timescales. acknowledgements we thank arne fjellberg for taxonomic examination of the collembola samples, dorota kidawa and lech iliszko for assistance in data collection and laboratory analyses during the bjørnøya and magdalenefjorden expeditions (respectively), and the university centre in svalbard and its staff, particularly steve coulson, for facilitating laboratory access during our work in isfjorden. this study was supported by the polish ministry of science and higher education (grant nos. 1883/p01/2007/32 and ipy/25/ 2007), the polish�norwegian research fund (pnrf-234ai-1/07), the faculty of biology, university of gdańsk (538-l120-0816-12), and the mary & clifford corbridge trust, cambridge, uk. the study was performed under permit from the governor of svalbard. references ávila-jiménez m.l. & coulson s.j. 2011. a holarctic biogeographical analysis of the collembola (arthropoda, hexapoda) unravels recent post-glacial colonization patterns. insects 2, 273�296. babenko a. 2000. collembolan assemblages of polar desert and subarctic nival communities. pedobiologia 44, 421�429. babenko a.b. 2009. are there many tundra species among collembola of the tundra belt? in s.i. golovatch et al. (eds.): species and communities in extreme environments. pp. 113�130. sofia: pensoft publishers. bardgett r.d. & chan k.f. 1999. experimental evidence that soil fauna enhance nutrient mineralization and plant uptake in montane grassland ecosystem. soil biology and biochemistry 31, 1007�1014. barton t.r. 1995. a modified technique for extracting live ticks from small soil and litter samples. experimental and applied acarology 19, 357�360. basset i.e., elliot g.p., walker k.j., thorpe s. & beggs j.r. 2014. are nesting seabirds important determinants of invertebrate community composition on subantarctic adams island. polar biology 37, 531�540. bengston s.-a., fjellberg a. & solhöy t. 1974. abundance of tundra arthropods in spitsbergen. entomologica scandinavica 5, 137�142. benoit j.b., elnitsky m.a., schulte g.g., lee r.e. jr. & denlinger d.l. 2009. antarctic collembolans use chemical signals to promote aggregation and egg laying. journal of insect behavior 22, 121�133. birkemoe t. & leinaas h.p. 2000. effects of temperature on the development of an arctic collembola (hypogatrura tullbergi). functional ecology 14, 693�700. block w. & convey p. 1995. the biology, life cycle and ecophysiology of the antarctic mite alaskozetes antarcticus (michael). journal of zoology 236, 431�449. bokhorst s., huiskes a., convey p. & aerts r. 2007. external nutrient inputs into terrestrial ecosystems of the falkland islands and the maritime antarctic. polar biology 30, 1315�1321. bokhorst s., huiskes a., convey p., van bodegom p.m. & aert r. 2008. climate change effects on soil arthropod communities from the falkland islands and the maritime antarctic. soil biology & biochemistry 40, 1547�1556. byzova j.b., uvarov a.v. & petrova a.d. 1995. seasonal changes in communities of soil invertebrates in tundra ecosystem of hornsund, spitsbergen. polish polar research 16, 245�266. callaghan t.v., björn l.o., chapin f.s. iii, chernov y., christensen t.r., huntley b., ims r., johansson m., riedlinger d.j., jonasson s., matveyeva n., oechel w., panikov n. & shaver g. 2005. arctic tundra and polar desert ecosystems. in c. symon et al. (eds.): arctic climate impact assessment*scientific report. pp. 243�352. cambridge: cambridge university press. caruso t. & bargagli r. 2007. assessing abundance and diversity patterns of soil microarthropod assemblages in northern victoria land (antarctica). polar biology 30, 895�902. caruso t., borghini f., bucci c., colacevich a. & bargagli r. 2007. modelling local-scale determinants and the probability of microarthropod species occurrence in antarctic soils. soil biology and biochemistry 39, 2949�2956. caruso t., trokhymets v., bargagli r. & convey p. 2013. biotic interactions as a structuring force in soil communities: evidence from the micro-arthropods of an antarctic moss model system. oecologia 172, 495�503. chown s.l. & convey p. 2007. spatial and temporal variability across life’s hierarchies in the terrestrial antarctic. philosophical transactions of the royal society b 362, 2307�2331. coulson s., hodkinson i.d., strathdee a., bale j.s., block w., worland m.r. & webb n.r. 1993. simulated climate change: the interaction between vegetation type and microhabitat temperatures at ny ålesund, svalbard. polar biology 13, 67�70. coulson s.j., convey p., aakra k., aarvik l., ávila-jiménez m.l., babenko a., biersma e., boström s., brittain j., carlsson a., christoffersen k.s., de smet w.h., ekrem t., fjellberg a., fuereder l., gustafsson d., gwiazdowicz d.j., hågvar s., hansen l.o., kaczmarek l., kolicka m., kuklin v., lakka h.-k., lebedeva n., makarova o., maraldo k., melekhina e., ødegaard f., pilskog h.e., simon j.c., sohlenius b., solhøy t., søli g., stur e., tanasevitch a., taskaeva a., velle g. & zmudczynska-skarbek k. 2014. the terrestrial and freshwater invertebrate biodiversity of the archipelagoes of the barents sea; svalbard, franz josef k. zmudczyńska-skarbek et al. is ornithogenic fertilization important for collembolan communities? citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 land and novaya zemlya. soil biology and biochemistry 68, 440�470. coulson s.j., fjellberg a., gwiazdowicz d.j., lebedeva n.v., melekhina e.n., solhøy t., erséus c., maraldo k., miko l., schatz h., schmelz r.m., søli g. & stur e. 2013. the invertebrate fauna of anthropogenic soils in the higharctic settlement of barentsburg, svalbard. polar research 32, article no. 19273, doi: http://dx.doi.org/10.3402/polar. v32i0.19273 coulson s.j., fjellberg a., snazell r., gwiazdowicz d.j. & ávila-jiménez m.l. 2011. on the collembola, araneae and gamasida from the kinnvika region of nordaustlandet, svalbard. geografiska annaler 93, 253�257. coulson s.j., hodkinson i.d. & webb n.r. 2003. microscale distribution patterns in high arctic soil microarthropod communities: the influence of plant species within the vegetation mosaic. ecography 26, 801�809. coulson s.j., leinaas h.p., ims r.a. & søvik g. 2000. experimental manipulation of the winter surface ice layer: the effects on a high arctic soil microarthropod community. ecography 23, 299�306. coulson s.j. & midgley n.g. 2012. the role of glacier mice in the invertebrate colonisation of glacial surfaces: the moss balls of the falljökull, iceland. polar biology 35, 1651�1658. croll d.a., maron j.l., estes j.a., danner e.m. & byrd g.v. 2005. introduced predators transform subarctic islands from grassland to tundra. science 307, 1959�1961. de smet w.h. & van rompu e.a. 1994. rotifera and tardigrada from some cryoconite holes on a spitsbergen (svalbard) glacier. belgian journal of zoology 124, 27�37. dollery r., hodkinson i.d. & jónsdóttir i.s. 2006. impact of warming and timing of snow melt on soil microarthropod assemblages associated with dryas-dominated plant communities on svalbard. ecography 29, 111�119. eklima 2014. monthly normal values. norwegian meteorological institute. accessed on the internet at http://sharki.oslo. dnmi.no on 14 july 2014. elvebakk a. 1994. a survey of plant associations and alliances from svalbard. journal of vegetation science 5, 791�802. eurola s. & hakala a.v.k. 1977. the bird cliff vegetation of svalbard. aquilo series botanics 15, 1�18. fjellberg a. 1994. the collembola of the norwegian arctic islands. meddelelser 133. oslo: norwegian polar institute. fjellberg a. 1997. collembola from nordaustlandet, svalbard. fauna norvegica b 44, 71�75. fjellberg a. 1998. the collembola of fennoscandia and denmark. part 1: poduromorpha. fauna entomologica scandinavica 35. leiden: brill. fjellberg a. 2007. the collembola of fennoscandia and denmark. part 2: entomobryomorpha and symphypleona. fauna entomologica scandinavica 42. leiden: brill. filser j. 2002. the role of collembola in carbon and nitrogen cycling in soil. pedobiologia 46, 234�245. gwiazdowicz d.j. & coulson s.j. 2011. high-arctic gamasid mites (acari, mesostigmata): community composition on spitsbergen, svalbard. polar research 30, article no. 8311, doi: http://dx.doi.org/10.3402/polar.v30i0.8311 hertzberg k., leinaas h.p. & ims r.a. 1994. patterns of abundance and demography: collembola in habitat patch gradient. ecography 17, 349�359. hertzberg k., yoccoz n.g., ims r.a. & leinaas h.p. 2000. the effects of spatial habitat configuration on recruitment, growth and population structure in arctic collembola. oecologia 124, 381�390. hodkinson i.d. 2013. terrestrial and freshwater invertebrates. in h. meltofte (ed.): arctic biodiversity assessment. status and trends in arctic biodiversity. pp. 247�275. akureyri: conservation of arctic flora and fauna. hodkinson i.d. & coulson s.j. 2004. are high arctic terrestrial food chains really that simple?*bear island food web revisited. oikos 106, 427�431. hodkinson i.d., coulson s., webb n.r, block w., strathdee a.t. & bale j.s. 1994. feeding studies on onychiurus arcticus (tullberg) (collembola: onychiuridae) on west spitsbergen. polar biology 14, 17�19. hogg i.d., cary s.c., convey p., newsham k., o’donnell t., adams b.j., aislabie j., frati f.f., stevens m.i. & wall d.h. 2006. biotic interactions in antarctic terrestrial ecosystems: are they a factor? soil biology and biochemistry 38, 3035�3040. hopkin s.p. 1997. biology of the springtails. insecta: collembola. oxford: oxford university press. hugo e.a., mcgeoch m.a., marshall d.j. & chown s.l. 2004. fine scale variation in microarthropod communities inhabiting the keystone species azorella selago on marion island. polar biology 27, 466�473. ims r.a. & ehrich d. 2013. terrestrial ecosystems. in h. meltofte (ed.): arctic biodiversity assessment. status and trends in arctic biodiversity. pp. 385�440. akureyri: conservation of arctic flora and fauna. ims r.a., leinaas h.p. & coulson s. 2004. spatial and temporal variation in patch occupancy and population density in a model system of an arctic collembola species assemblage. oikos 105, 89�104. jakubas d., zmudczynska k., wojczulanis-jakubas k. & stempniewicz l. 2008. faeces deposition and numbers of vertebrate herbivores in the vicinity of planktivorous and piscivorous seabird colonies in hornsund, spitsbergen. polish polar research 29, 45�58. kolb g.s., jerling l., essenberg c., palmborg c. & hambäck p.a. 2012. the impact of nesting cormorants on plant and arthropod diversity. ecography 35, 726�740. kolb g.s., young h.s. & anderson w.b. 2011. effects of seabirds on islands consumers. in c.p.h. mulder et al. (eds.): seabird islands. ecology, invasion and restoration. pp. 212�241. new york: oxford university press. leinaas h.p. 1983. synchronized moulting controlled by communication in group living collembola. science 219, 193�195. lindeboom h.j. 1984. the nitrogen pathway in a penguin rookery. ecology 65, 269�277. loeng h. & drinkwater k. 2007. an overview of the ecosystems of the barents and norwegian seas and their is ornithogenic fertilization important for collembolan communities? k. zmudczyńska-skarbek et al. 12 (page number not for citation purpose) citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 http://dx.doi.org/10.3402/polar.v32i0.19273 http://dx.doi.org/10.3402/polar.v32i0.19273 http://sharki.oslo.dnmi.no http://sharki.oslo.dnmi.no http://dx.doi.org/10.3402/polar.v30i0.8311 http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 response to climate variability. deep-sea research part ii 54, 2478�2500. matula j., pietryka m., richter d. & wojtun b. 2007. cyanoprokaryota and algae of arctic terrestrial ecosystems in the hornsund area, spitsbergen. polish polar research 28, 283�315. mulder c.p.h., anderson w.b., towns d.r. & bellingham p.j. (eds.) 2011. seabird islands. ecology, invasion and restoration. new york: oxford university press. odasz a.m. 1994. nitrate reductase activity in vegetation below an arctic bird cliff, svalbard, norway. journal of vegetation science 5, 913�920. orgeas j., vidal e. & ponel p. 2003. colonial seabirds change beetle assemblages on a mediterranean island. ecoscience 10, 38�44. payer d.c., josefson a.b. & fjeldså j. 2013. species diversity in the arctic. in h. meltofte (ed.): arctic biodiversity assessment. status and trends in arctic biodiversity. pp. 67�77. akureyri: conservation of arctic flora and fauna. peres-neto p.r., legendre p., dray s. & borcard d. 2006. variation partitioning of species data matrices: estimation and comparison of fractions. ecology 87, 2614�2625. rusek j. 1998. biodiversity of collembola and their functional role in the ecosystem. biodiversity and conservation 7, 1207�1219. saskaug e., johnsen g.h. & kovacs k.m. (eds.): 2009. ecosystem barents sea. trondheim: tapir academic press. sinclair b.j. & sjursen h. 2001. terrestrial invertebrate abundance across a habitat transect in keble valley, ross island, antarctica. pedobiologia 45, 134�145. sømme l. & birkemoe t. 1999. demography and population densities of folsomia quadrioculata (collembola, isotomidae) on spitsbergen. norwegian journal of entomology 46, 35�45. statsoft, inc. team 2011. statistica, version 10. tulsa, ok: statsoft, inc. stempniewicz l., błachowiak-samołyk k. & wȩsławski j.m. 2007. impact of climate change on zooplankton communities, seabird populations and arctic terrestrial ecosystem* a scenario. deep-sea research part ii 54, 2934�2945. summerhayes v.s. & elton c.s. 1923. contributions to the ecology of spitsbergen and bear island. journal of ecology 11, 214�286. ter braak c.j.f. & šmilauer p. 2012. canoco reference manual and user’s guide: software for ordination (version 5.0). ithaca, ny: microcomputer power. towns d.r., wardle d.a., mulder c.p.h., yeates g.w., fitzgerald b.m., parrish g.m., bellingham p.j. & bonner k.i. 2009. predation of seabirds by invasive rats: multiple indirect consequences for invertebrate communities. oikos 118, 420�430. usher m.b. & booth r.g. 1984. arthropod communities in a maritime antarctic moss�turf habitat: three-dimensional distribution of mites and collembola. journal of animal ecology 53, 427�441. usher m.b. & booth r.g. 1986. arthropod communities in a maritime antarctic moss�turf habitat: multiple scales of pattern in the mites and collembola. journal of animal ecology 55, 155�170. uvarov a.v. & byzova j.b. 1995. species diversity and distribution of collembola in the vicinity of polish polar station, hornsund area, spitsbergen. polish polar research 16, 233�243. worland m.r. & lukešová a. 2000. the effect of feeding on specific soil algae on the cold-hardiness of two antarctic microarthropods (alaskozetes antarcticus and cryptopygus antarcticus). polar biology 23, 766�774. wright d.g., van der wal r., wanless s. & bardgett r.d. 2010. the influence of seabird nutrient enrichment and grazing on the structure and function of island soil food webs. soil biology & biochemistry 42, 592�600. zmudczyńska k., olejniczak i., zwolicki a., iliszko l., convey p. & stempniewicz l. 2012. influence of allochtonous nutrients delivered by colonial seabirds on soil collembolan communities on spitsbergen. polar biology 35, 1233�1245. zmudczyńska k., zwolicki a., barcikowski m., barcikowski a. & stempniewicz l. 2009. spectral characteristics of the arctic ornithogenic tundra vegetation in hornsund area, sw spitsbergen. polish polar research 30, 249�262. zmudczyńska k., zwolicki a., barcikowski m., iliszko l. & stempniewicz l. 2008. variability of individual biomass and leaf size of saxifraga nivalis l. along transect between seabirds colony and seashore in hornsund, spitsbergen. ecological questions 9, 37�44. zmudczyńska-skarbek k., barcikowski m., zwolicki a., iliszko l. & stempniewicz l. 2013. variability of polar scurvygrass cochlearia groenlandica along a seabird influenced gradient across spitsbergen tundra. polar biology 36, 1659�1669. zwolicki a., zmudczyńska-skarbek k., iliszko l. & stempniewicz l. 2013. guano deposition and nutrient enrichment in the vicinity of planktivorous and piscivorous seabird colonies in spitsbergen. polar biology 36, 363�372. k. zmudczyńska-skarbek et al. is ornithogenic fertilization important for collembolan communities? citation: polar research 2015, 34, 25629, http://dx.doi.org/10.3402/polar.v34.25629 13 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25629 http://dx.doi.org/10.3402/polar.v34.25629 doi:10.3402/polar.v33.17236 r e s e a r c h / r e v i e w a r t i c l e late holocene climate change recorded in proxy records from a bransfield basin sediment core, antarctic peninsula alex barnard,1 julia s. wellner1 & john b. anderson2 1 department of earth and atmospheric sciences, university of houston, 4800 calhoun road, houston, tx 77204, usa 2 department of earth science, rice university, ms-126, 6100 main street, houston, tx 77005, usa keywords antarctic peninsula; palaeoclimate; holocene; marine; isotopes. correspondence alex barnard, department of earth and atmospheric sciences, university of houston, 4800 calhoun road, houston, tx 77204, usa. e-mail: abarnard2@uh.edu abstract the glacimarine environment of the antarctic peninsula region is one of the fastest warming places on earth today, but details of changes in the recent past remain unknown. large distances and widespread variability separate late holocene palaeoclimate reconstructions in this region. this study focuses on a marine sediment core collected from ca. 2000 m below sea level in the central bransfield strait that serves as a key for understanding changes in this region. the core yielded a high sedimentation rate and therefore provides an exceptional high-resolution sedimentary record composed of hemipelagic sediment, with some turbidites. an age model has been created using radiocarbon dates that span the late holocene: 3560 cal yr bp to present. this chronostratigraphic framework was used to establish five units, which are grouped into two super-units: a lower super-unit (3560�1600 cal yr bp) and an upper super-unit (1600 cal yr bp�present), based on facies descriptions, laser particle size analysis, x-ray analysis, multi-sensor core logger data, weight percentages and isotopic values of total organic carbon and nitrogen. we interpret the signal contained within the upper super-unit as an increase in surface water irradiance and/or shortening of the sea-ice season and the five units are broadly synchronous with climatic intervals across the antarctic peninsula region. while the general trends of regional climatic periods are represented in the bransfield basin core we have examined, each additional record that is obtained adds variability to the known history of the antarctic peninsula, rather than clarifying specific trends. the antarctic peninsula is a rapidly warming region that encompasses both marine and glacial environments. records spanning the past 50 years from the antarctic peninsula show a temperature increase of 0.568c per decade when averaged over the year, and an increase of 1.098c per decade in the austral winter months, compared to the global mean of 0.138c90.03 per decade (turner et al. 2005). austral winter temperatures in parts of the antarctic peninsula region have risen by about 68c over the past 50 years. in addition, in recent years the western antarctic peninsula region has experienced more intense ocean warming than the global average, more than 18c since 1950, as well as increased salinity, in the upper 100 m (meredith & king 2005). thus current warming across the antarctic peninsula region is unusual in both synchronicity and extent (e.g., cook et al. 2005; steig et al. 2009; mulvaney et al. 2012). this contrasts with published palaeoclimate records taken from marine sediment cores that document diachronous climatic change throughout the holocene. an understanding of the historical context of this rapid, regional climate change is necessary for the development of models of future changes. to elucidate the late holocene climatic changes occurring in different parts of the bransfield basin, and their relationships to one another, this study compares new data from a central position in the region with four marine-based sedimentary records derived from similar methods (domack et al. 2001; heroy et al. 2008; michalchuk et al. 2009; milliken et al. 2009) (fig. 1). polar research 2014. # 2014 alex barnard et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 environmental setting the antarctic peninsula is the warmest and wettest part of antarctica. storms, generated in the amundsen sea, track into the bellingshausen sea, deflect north along the antarctic peninsula, and eventually reach the scotia sea. because of these storms, the western/northern seaboard of the antarctic peninsula has a comparatively warm, humid climate. in comparison, the eastern side is colder and drier (reynolds 1981). the dominant controls of temperature and precipitation patterns across the peninsula are storms and orographic effects. temperature differences between the north and south are controlled by latitudinal temperature gradients. temperature data from across the antarctic peninsula (reynolds 1981; vaughan & doake 1996) document a broad, regional, thermal control of ice shelves on the western antarctic peninsula. ice shelves exist only on the cold side of the �5 to �98c isotherm (vaughan & doake 1996). moreover, temperature changes affect glacial sediment yields as shown by recent increases in sediment accumulation rates from the antarctic peninsula to patagonia (boldt et al. 2013). the source of coastal waters in antarctica is the midlevel water mass of the antarctic circumpolar current, which is composed of warm, saline, circumpolar deep water. circumpolar deep water is divided into upper and lower units, with the upper circumpolar deep water distinguished by its relatively warm temperature and the fig. 1 inset shows the location of the antarctic peninsula. main figure is a regional map of the western antarctic peninsula study area including multibeam bathymetry from the international bathymetric chart of the southern ocean (arndt et al. 2013), created using fledermaus software (quality positioning systems bv, zeist, netherlands). the location of the antarctic circumpolar current (acc) and bransfield current are shown. four study sites with published records that data in this study are compared to are as follows: (1) domack et al. (2001); (2) heroy et al. (2008); (3) michalchuk et al. (2009); and (4) milliken et al. (2009) and majewski et al. (2012). this study (5) is the site of core jpc-24, collected during nbp0703. palaeoclimate record from bransfield basin sediment core a. barnard et al. 2 (page number not for citation purpose) citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 lower circumpolar deep water by its relatively high salinity. the antarctic circumpolar current bifurcates around the south shetland islands and traverses the length of the northern bransfield strait as the bransfield current (meredith et al. 2010), and has in recent years provided regular intrusions of upper circumpolar deep water onto the continental shelf (ducklow et al. 2007). this is important because the upper circumpolar deep water is 3�48c above freezing, significantly warmer than the bransfield strait water temperature that varies seasonally between 0 and �28c in the austral summer and winter, respectively. in this region, where the average thickness of sea ice is less than 1 m, a 18c increase in surface ocean temperature is equivalent to a 30 cm reduction in the formation of sea ice (meredith & king 2005). the presence of upper circumpolar deep water has also been associated with increases in productivity (prezelin et al. 2000). since the last glacial maximum, when grounded ice reached the continental shelf and perennial sea ice covered the bransfield strait (heroy & anderson 2005, 2007; simms et al. 2011), ice has continued to retreat with some minor re-advances. bentley et al. (2009) provide a synthesis of the holocene climate and outline five periods. three warm periods (mid-holocene warm period, medieval warm period and the recent rapid warming) that are associated with warmer ocean waters, higher productivity and higher sedimentation rates. two intervening cold periods (neoglacial and little ice age) are associated with intense perennial sea ice and colder air temperatures. climate controlled the sedimentary evolution of the western antarctic peninsula throughout the holocene, regionally determining the pattern and volume of sediment delivery and facies variability (griffith & anderson 1989). the present-day synchronous rapid warming of the antarctic peninsula contrasts with published holocene marine sediment core records that document diachronous climatic changes across the region (domack et al. 2001; heroy et al. 2008; michalchuk et al. 2009; milliken et al. 2009; majewski et al. 2012). palaeoenvironmental proxy data in these studies shows that late holocene climate change was broadly synchronous in extent, although the timing varied with latitude and location. published proxy records suggest that the onset of the neoglacial varies with distance from the continent, occurring earlier in the sites closest to the antarctic peninsula and later in the more northerly sites (domack et al. 2001; taylor & sjunneskog 2002; heroy et al. 2008; michalchuk et al. 2009; milliken et al. 2009). the existence of a medieval warm period and a little ice age in antarctica is uncertain since each has been documented in only a few records (bentley et al. 2009). study area the study area is the bransfield strait in the northwestern antarctic peninsula (fig. 1). this area lies adjacent to the most northerly part of the antarctic continent, and extends north into the southern ocean to 638s. along the northern continental margin of the antarctic peninsula lie the south shetland islands. these islands are separated from the antarctic peninsula by the bransfield strait, a distance of about 125 km (fig. 1). the strait opens in the west to the bellingshausen sea and in the east to the weddell sea and is the geographic counterpart of the geologic bransfield basin. the basin is further subdivided into three domains: the west bransfield basin, the central bransfield basin and the east bransfield basin. the flat-bottomed part of the central bransfield basin adjacent to king george island is known as the king george sub-basin. methods the data used in this study were collected in 2007 onboard the rv/ib nathaniel b. palmer, during cruise nbp0703. real-time geophysical data were analysed onboard and used to identify a coring location in the kinggeorge sub-basin of the central bransfield basin where undisturbed hemipelagic sediment would be sampled (garcı́a et al. 2008). jumbo piston core jpc-24 (22 m) and jumbo trigger core jtc-24 (1.33 m) were recovered from a water depth of 1980 m (628 16.449?s, 578 38.7000?w; fig. 2). a hull mounted bathy 2000 (ocean data equipment corporation, warwick, ri, usa) unit fig. 2 bathymetry of the bransfield basin. location of fig. 3 is shown as a red line with core locations as a green circle. map created using geomapapp (carbotte et al. 2007). a. barnard et al. palaeoclimate record from bransfield basin sediment core citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 with a 3.5 khz swept frequency source was used in conjunction with an em120 multibeam unit (simrad, horten, norway) to provide a detailed image of the seafloor and upper sediment layers (figs. 2, 3). in the onboard laboratory, detailed sediment core analyses were completed including: colour (using a munsell colour chart), grain size and sedimentary and biogenic structures. the core was also digitally recorded using a camera and then sampled for a preliminary study of the sediment composition. radiocarbon dates seven carbonate samples collected from the core were sent to the university of california irvine for accelerated mass spectrometry dating. the calib v.6 software program was used for calibration and correction (stuiver et al. 2005). a dr of 700 years was added to the standard marine reservoir correction of about 350�400 years, giving the 1100-year correction appropriate for antarctic waters (domack et al. 2001; milliken et al. 2009). the dates are provided in table 1. sedimentology the sediment cores were described as part of nbp0703 and detailed facies descriptions, and sampling intervals were conducted at the antarctic research facility, florida state university. the core contains four main facies that include green silty clay, dark olive grey silt, very poorly sorted sand and clay and fining upwards sandy layers. sediment magnetic susceptibility and density were recorded at 1 cm intervals using an mscl 7.6 (geotek, deventry, uk). artefacts caused both by division of the core into individual sections and zones of incomplete core recovery have been removed from the data. additional samples were collected for laser particle size analysis at 10 cm intervals. measurements were conducted using a mastersizer 2000 (malvern instruments, worcester, uk). magnetic susceptibility is used to estimate relative abundance of terrigenous versus biogenic material following anderson (1999). x-ray radiographs were supplied by the antarctic research facility at a 1:1 scale at 300 dpi, used as a non-invasive techniques to find pebbles (�4 mm) down core at 5 cm intervals. geochemistry for geochemical analysis, we collected 107 samples. samples (10 cc) were taken at 20 cm intervals down core, in 1 cm diameter sample tubes. sample preparation followed methods outlined in milliken et al. (2009). samples were analysed at the university of california davis. isotopic values and elemental values of carbon and nitrogen were measured using continuous flow mass spectrometry. precision of the measurements is 90.1� for isotopic values (d) of carbon, 90.2� for nitrogen, fig. 3 chirp 3.5 khz sub-bottom profile, y-axis is depth and x-axis is distance. vertical exaggeration in the bathymetric profile is approximately 40. inset: changes in the core lithology (jpc-24) correlate with acoustic reflection surfaces. the location is shown in fig. 2. inset: core lithology represented by colours, where green is clayey mud, orange is clay, grey is sand�gravel and mottling represents abundant organic matter. vertical bars are grain size, from left to right: clay, sand, gravel. table 1 dates were calibrated using calib v.6.0 software and using the marine 04.14c calibration curve that incorporates a 350�400 years correction (stuiver et al. 2005). a marine reservoir dr of 700 years was added, making the total marine reservoir correction about 1100 years. lab. no. core depth (cm) fraction modern (�) 9 d14c (�) 9 14c age (bp) 9 cal yr bp 9a 69391 0 b 0.87 0.0013 �126 1.3 1080 15 �57d 2 69389 490c 0.76 0.0013 �242 1.3 2225 15 1081 37 40843 556 c 0.78 0.0021 �219 2.1 1985 25 832d 44 69390 671b 0.75 0.0010 �254 1.0 2360 15 1228 32 40852 1273 c 0.70 0.0021 �300 2.1 2865 25 1759d 43 40850 1692 0.63 0.0017 �368 1.7 3680 25 2750 11 40853 2194 c 0.58 0.5821 �418 6.2 4350 90 3559d 54 a 1s error of calibrated age. b from articulated shells. c from shell fragment material. d dates used in the radiocarbon age model. palaeoclimate record from bransfield basin sediment core a. barnard et al. 4 (page number not for citation purpose) citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 0.5% for carbon (mg), and 0.1% for nitrogen (mg). organic carbon and nitrogen results were normalized using the weight of sediment (mgc, n/sediment weight [mg]) to give weight percentages (wt.%). the isotopic values were supplied by the university of california davis in parts per thousand (�), relative to pee dee belemnite (pdb) (carbon) and air (nitrogen). we have adapted the calculation of mass accumulation rates from willmott et al. (2009) that uses the elemental concentration of carbon and nitrogen, dry bulk density and sedimentation rate to calculate organic matter mass accumulation rates by removing dry bulk density. including dry bulk density as calculated from multi-sensor core logger density does not change the mass accumulation rates significantly and it is therefore omitted allowing use of the equation over a broader range of data sets. the equation we use is: mass accumulation rateðtoc; nþ ¼ toc; n ðwt%þ 100 � sedimentation rate ðcm yr�1þ (1) results geophysical analysis and core integration core jpc-24 and jtc-24 were recovered from the 2000 m deep king george sub-basin. the core is mostly composed of green-grey diatomaceous silty clays and clayey silt. continuous parallel reflections in the subbottom profile correlate with the jpc-24 core lithology, suggesting the complete recovery of recent sediments. results from a trigger core (jtc-24) taken at the same location corroborate the integrity of the core top. radiocarbon age model the highest stratigraphic date was recovered from 0 cm and yielded an age of 0 calibrated years before present (cal yr bp; laboratory number 69391; table 1). since it is difficult to use radiocarbon dating techniques on material younger than 1950, we set our 0 cal yr bp date to represent the most recent sediment, and acknowledge that this tallies with our linear age model. a simple linear interpolation age model has been constructed for the youngest radiocarbon dates (fig. 4) and is used to convert depth in core (cm) to cal yr bp. of the seven carbonate samples dated we chose the four youngest dates to construct an age model for this core, including the core-top zero date. three older dates that do not fall in chronological order, along a linear regression of the youngest dates, are only older by a few hundred years and reinforce the existing age model, providing a possible age range for delivery of reworked sediments to the deep bransfield basin. super-units and units according to our age model we present two super-units and five units that have been recognized based on facies analysis, grain size data, magnetic susceptibility, pebble count, and weight percentages, ratio and isotopic values of carbon and nitrogen (fig. 5). for the whole data set, fig. 4 age model for the radiocarbon dates, constructed by linear interpolation, showing 1s error bars. because 1950 ad is equivalent to 0 cal yr bp, the age model uses negative values on the x axis to reach 2007 ad ( �57 cal yr bp). the calculated sedimentation rate, based on a linear interpretation from the origin to 22 m at 3559 cal yr bp, is 0.6 cm/yr. a. barnard et al. palaeoclimate record from bransfield basin sediment core citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 fig. 5 grain size (sand, silt, clay percentages), multi-sensor core logger data (density and magnetic susceptibility), pebble count, elemental and isotopic data (total organic carbon and nitrogen (wt.%), d13c, d15n (�) and the c/n atomic ratio) for units and super-units throughout jpc-24 plotted by age (cal yr bp). palaeoclimate record from bransfield basin sediment core a. barnard et al. 6 (page number not for citation purpose) citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 the average mean d13c and d15n values are �25 � and 5�, respectively, with ranges of ca. 2� (d13c) and ca. 4� (d15n). the lower super-unit covers the age range 3560�1600 cal yr bp, and the upper super-unit from 1600 cal yr bp�present. average mean values for total organic carbon and nitrogen (wt.%) are 0.75 and 0.12, respectively, and the average mean atomic c/n ratio is 5.3. the upper super-unit has higher average mean values of total organic carbon and nitrogen (wt.%), and d13c that are higher than the mean average and lower d15n values. comparison of the weight percentages and facies shows that the lowest values occur in coarser sediments. in contrast, the lower super-unit has averagemean isotopic signature values that are higher that the data set averages for d15n, and lower for d13c. unit boundaries are defined by relatively small changes in the proxy data, resulting in less well-defined boundaries between units: 1/2, 3/4 and 4/5. units. unit 1 (3560�2600 cal yr bp) is composed of hemipelagic sediment with some distal turbidites, and includes the highest sustained d15n values within this core, with values consistently above the data set mean average. unit 2 (2600�1600 cal yr bp) is characterized by organic-rich hemipelagic sediment including three turbidites, and lower d15n values through the middle of the unit. unit 3 (1600�500 cal yr bp) is dominated by organic-rich hemipelagic sediment and includes a layer of abundant angular granules interpreted as ice-rafted debris. the maximum d13c value, �24�, occurs in unit 3 along with above average concentrations of carbon and nitrogen. unit 4 (500�50 cal yr bp) is composed of low density, low magnetic susceptibility hemipelagic sediment, with no pebbles and less sand relative to the other units (vol.%). throughout units 3 and 4, d15n decreases toward the core top, with a slight increase in d15n values in unit 4. unit 5 is characterized by a wider range of d15n values and high d13c values ( �24.2�). discussion the ratio of biogenic to terrigenous sediment determines the magnetic susceptibility character. high percentages of biogenic sediment result in relatively low magnetic susceptibility values, and high percentages of terrigenous sediment produce high magnetic susceptibility values. consequently, magnetic susceptibility has been widely implemented as a proxy for the ratio of marine to landderived sediment. from 1600 cal yr bp to present, low magnetic susceptibility is more frequent in the upper super-unit, and most probably represents an increase in the accumulation of marine organic matter at this time. in glacimarine environments coarse sediments, grain size greater than 4 mm, are typically interpreted as icerafted debris. the importance of sea ice in the bransfield strait for sedimentation is well defined by extreme levels of seasonal variability in the particle flux. as much as 97�99% of the mass flux occurs during the austral summer (wefer et al. 1988; khim et al. 2005). ice-rafted debris is delivered to the deep basin either by sea ice or by icebergs, meaning that it also requires open ocean conditions. units 1 and 3 contain the highest pebble counts indicating a larger contribution of ice-rafted debris and also low magnetic susceptibility values. these proxies reveal the increased relative inputs of marine organic accumulation and terrigenous material from ice-rafted debris, not turbidites. the dominance of marine organic matter and ice-rafted debris in the sedimentary record establishes that open ocean conditions prevailed during those times. more restricted ice cover allows for more efficient dispersal of ice-rafted debris across the basin. most of the sediment in jpc-24 (90%) is homogeneous hemipelagic sediment with a mean average c/n ratio of 5.3. the results in this study show a very strong positive correlation (correlation coefficient of 0.98) between carbon and nitrogen with a very low standard deviation (0.04). we interpret these results to mean that the carbon and nitrogen isotopic signature represents marine organic matter. in fig. 6 the best-fit line of the carbon and nitrogen data crosses the origin signifying that that these samples contain negligible amounts of inorganic carbon or nitrogen. the slope of the c/n ratio is 5.1, close to the stoichiometry found in the traditional redfield ratio (ca. 6.6 [redfield 1934]). to achieve the redfield ratio marine organisms must achieve a balanced lifestyle requiring limiting nutrients and tolerable levels of environmental stress. when balance is not achieved the redfield ratio becomes a broader realm of c/n values between 3 and 8.75 (jørgensen & bendoricchio 2001). phytoplankton attain the redfield ratio when growing at their maximum growth rate (goldman et al. 1979) and if the supply of nutrients is sufficient that no single nutrient limits growth, then the only limitation of biomass is the quantity of nutrients available. from this data we infer that changes in the isotopic signature are likely to represent changes in surface biomass (productivity). the carbon isotopic signature in our data has a mean average d13c value of �24 � that can be explained by the sources and metabolic pathways used. sources of carbon for marine phytoplankton are dissolved-marine bicarbonate with a d13c value of ca. 0� and dissolved co2 that has a d 13 c value of ca. �6� (meyers 1994). marine phytoplankton use the photosynthetic c3 pathway that creates an isotopic shift in of about �20�, as a a. barnard et al. palaeoclimate record from bransfield basin sediment core citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 function of dissolved co2, temperature, light and nutrient supply (meyers 1997). the trend toward higher d13c values in the younger parts of the core (fig. 7) could be driven by the ‘‘coldwater effect’’ proposed by rau et al. (1989) whereby increased isotopic discrimination toward 12 c occurs when the abundance of dissolved co2 increases. additionally, the concentration of dissolved co2 is higher in cold water so it is preferentially incorporated during photosynthetic activity over marine bicarbonate. light is also an important factor in surface waters and the amount of irradiance can influence d13c values; in laboratory experiments exposure to increased levels of irradiance over a 24-h period caused 1.5� higher d13c values in phytoplankton (burkhardt et al. 1999). changes in the environmental conditions are expected to be related to changes in diatom assemblages. using a sedimentary record from the central bransfield basin, barcena et al. (1998) showed that there has been an increase in the amount of diatom sea-ice taxa over the last 2000 years. the range of carbon isotopic values changes quite dramatically during seasonal sea ice diatom taxa variations by up to 10� (henley et al. 2012). because our d13c values only change by 1�1.5�, it is possible that only small modifications to the assemblages are driving the changes we observe. it is unlikely that our results represent transfer from autotrophic to heterotrophic communities because this would result in a step-wise enrichment of both d15n (3.5�) and d13c (1.5�) values (rau et al. 1983; minagawa & wada 1984). it therefore seems reasonable to attribute the increase in d13c values at 1600 cal yr bp to changes in the environmental conditions that affected the diatom assemblages. using both the carbon and nitrogen isotopic signatures, plotted with the mass accumulation rate of organic matter, provides an insight into the ratio of productivity in surface waters to accumulation on the seafloor. figure 8 shows fig. 6 atomic carbon and nitrogen ratio of organic matter. the correlation coefficient for the best-fit line is 0.99. the traditional redfield ratio has a slope between 3 and 8 and here the best-fit line has a slope of 5.1. fig. 7 three-dimensional plot of d13c and c/n ratio. the highest d13c values occur in the youngest parts of the core. palaeoclimate record from bransfield basin sediment core a. barnard et al. 8 (page number not for citation purpose) citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 that d13c and total organic carbon mass accumulation values have a positive relationship, whereas d15n values and nitrogen mass accumulation values have a negative relationship. this is further evidence that there is a strong relationship between the accumulation of organic matter in sediment and the isotopic signature. the organic matter provides a record of isotopic fractionation during primary production related to surface water processes. the utilization of different nitrogen compounds in surface waters is controlled by the uptake of different compounds of nitrogen so the d15n signature changes as a function of the compound used. the mean average d15n of the marine organic matter in this core is 5�, a value similar to that of nitrate entering the oceans via continental runoff (5�10�). in the upper super-unit there is a trend towards lower d15n values. so long as the nutrient supply maintains an abundance of surface 14 [n]-no3 � , increases in productivity result in lower d15n values than would be expected with increasing levels of productivity (meyers 1997; altabet & francois 2001). nutrient supply levels are so high in the antarctic peninsula region that they fuel not just local but also regional increases in productivity (ardelan et al. 2010). in the bransfield strait during the austral summer, regenerated production using ‘‘recycled’’ ammonium with lower d15n values accounts for more than 80% of the total primary production (koike et al. 1986). regenerated production can also be fuelled by ammonium (nh4 � ) produced by phytoplankton as a mechanism to lose excess energy gained from increased levels of irradiance (lomas et al. 2000). recent studies of the mixed layer depth and nitrate assimilation in the southern ocean strongly suggest that light limitation is the dominant control of nitrate assimilation (difiore et al. 2010). an increase in regenerated production could alter the d15n values in relative isolation from the d13c values resulting in a decoupled d13c and d15n signal. irradiance of surface waters causes increased late summer levels of regenerated production and can change the community structure. differential uptake and remineralization following a seasonal pattern has also been observed (lourey et al. 2003). coincident maximums for both mass flux and regenerated production occur in the late summer. the concomitant increases in late summer (january�february) regenerated production and mass flux result in a greater preservation potential of the isotopic signature. correlation of units to late holocene climate periods climate records from the maritime western antarctic peninsula feature regional heterogeneity and the results in this paper allow new comparisons and correlation of late holocene climate changes to be made (fig. 9). unit 1 (3560�2600 cal yr bp) is broadly synchronous with the later stages of the mid-holocene warm period (fig. 9), a period of warmth, reduced sea ice and greater melt-waterderived sedimentation (bentley et al. 2009). the midholocene warm period is seen in many records from this region, ending in palmer deep at 3360 (domack et al. 2001), in the bransfield strait (heroy et al. 2008) and maxwell bay (milliken et al. 2009; majewski et al. 2012) at 2000�2600 cal yr bp, and in the firth of tay at 3500 cal yr bp (michalchuk et al. 2009). unit 2 (2600�1600 cal yr bp) is broadly synchronous with the neoglacial interval, a period of pronounced shift to colder climate on land and increased sea ice and cooler waters at fig. 8 total organic carbon and nitrogen mass accumulation rate, d13c and d15n values cross-plot with best-fit lines, correlation coefficients for nitrogen 0.48 and carbon 0.41, standard deviation of 0.69 and 0.36, respectively. a. barnard et al. palaeoclimate record from bransfield basin sediment core citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 sea (bentley et al. 2009). cores from the palmer deep (domack et al. 2001) and firth of tay (michalchuk et al. 2009) document the neoglacial interval as a period of cooling continuing through to the recent rapid warming (fig. 9). unit 3 (1600�500 cal yr bp) is broadly synchronous with the medieval warm period (bentley et al. 2009; lu et al. 2012), observed in proxy data from maxwell bay (milliken et al. 2009; majewski et al. 2012), and the bransfield basin (heroy et al. 2008 and this study). el niño southern oscillation records peak at 1200 cal yr bp, providing a potential explanation for the greater variability in proxy data from this study at that time (bentley et al. 2009). other studies from the region also document increased sea-surface temperatures following 1600�2000 cal yr bp (nielsen et al. 2004). prior to 650 cal yr bp the climate warmed, shown by the fact that the collins ice cap on king george island was at or landward of its present extent (hall 2007) and in the western antarctic peninsula ice extent was at or behind its present extent between 970 and 700 cal yr bp (hall et al. 2010). unit 4 (500�50 cal yr bp) is similar in timing to the little ice age (bentley et al. 2009; lu et al. 2012), and also coincides with a decrease in productivity at the palmer deep (sjunneskog & taylor 2002). land-based records show glacier advances at this time, for example the collins ice cap advanced at 650 cal yr bp (hall 2007). in palmer deep, the little ice age is dated between 700 and 150 cal yr bp (domack et al. 2001). unit 5 (50 cal yr bp�present) is equivalent to the present-day recent rapid warming. it has been recognized in numerous proxy records by higher sedimentation rates, increased total organic carbon, more ice-rafted debris and higher clay percentages (bentley et al. 2009; lu et al. 2010). these diachronous late holocene climatic changes that coincide with the neoglacial, medieval warm period, little ice age and recent rapid warming highlight the importance of global climate to this region. summary and conclusions this study defines two super-units and five units that are broadly synchronous with known climatic intervals across the antarctic peninsula region. an interval representing a climatic change is defined by the super-unit boundary at approximately 1600 cal yr bp. since then, the climate in the bransfield strait has changed and these changes are recorded in diatom productivity proxies in the sediments. correlation to other proxy records from the region (domack et al. 2001; heroy et al. 2008; michalchuk et al. 2009; milliken et al. 2009; majewski et al. 2012) indicates that these late holocene changes are broadly synchronous, yet high-resolution studies are starting to show that each area has its own detailed history, unlike the changes happening across the antarctic peninsula today. the integrated proxy data show that regional climatic changes, previously identified in more proximal locations, can be identified in holocene sediments accumulating in fig. 9 summary showing the warm (pink) and cold (blue) periods defined in other studies and compared to this study. bentley et al. (2009) presented a summary including onshore and offshore work but the timings of the changes are uncertain and are shown as gaps. the other six columns are marine records organized geographically from south-west to north-east. terms are abbreviated as follows: recent rapid warming (rrw); little ice age (lia); medieval warm period (mwp); neoglacial (neog); mid-holocene warm period (mhwp). palaeoclimate record from bransfield basin sediment core a. barnard et al. 10 (page number not for citation purpose) citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 the deep bransfield basin. this suggests that drill cores obtained from the bransfield basin in the future could be used to reconstruct older late quaternary glacial� interglacial cycles. records from the key time periods include material derived from the glacimarine environment during glacial advances and retreats. detailed analysis of the geochemical data allows us to make some general conclusions about the marine environmental conditions at the time of deposition. since 1600 cal yr bp, the isotopic signatures of carbon and nitrogen document a change in the surface water conditions that are recorded by the geochemical characteristics of the diatom assemblages. the similarity of the c/n ratio to the traditional redfield ratio indicates an autochthonous marine planktonic source for the organic matter unlimited by nutrients. variations in the amount of organic matter in the sediment correlate well with changes in the isotopic signature, interpreted as a record of surface water biogeochemical fractionation. seasonal maximums in organic matter reaching the basin floor and regenerated production during the summer sea ice free season provide a geochemical signature of the past environmental conditions. the changes observed were likely to have been driven by increases in surface water irradiance as the sea-ice season shortens. acknowledgements we acknowledge the national science foundation for funding this project (opp-0739596 to jsw and jba). we thank the science party of nbp0703, rice university sedimentology laboratory, petroleum systems and geochemistry program at the university of houston, steve ackley for discussion of sea-ice trends, qi fu and three anonymous reviewers. references altabet m.a. & francois r. 2001. nitrogen isotope biogeochemistry of the antarctic polar frontal zone at 1708w. deep-sea research part ii 48, 4247�4273. anderson j.b. 1999. antarctic marine geology. cambridge: cambridge university press. ardelan m.v., holm-hansen o., hewes c.d., reiss c.s., silva n.s., dulaiova h., steinnes e. & sakshaug e. 2010. natural iron enrichment around the antarctic peninsula in the southern ocean. biogeosciences 7, 11�25. arndt j.e., werner schenke h., jakobsson m., nitsche f.o., buys g., goleby b., rebesco m., bohoyo f., hong j., black j., greku r., udintsev g., barrios f., reynoso-peralta w., taisei m. & wigley r. 2013. the international bathymetric chart of the southern ocean (ibcso) version 1.0. a new bathymetric compilation covering circum-antarctic waters. geophysical research letters 40, 3111�3117. barcena m.a., gersonde r., ledesma s., fabres j., calafat a.m., canals m., sierro f.j. & flores j.a. 1998. record of holocene glacial oscillations in bransfield basin as revealed by siliceous microfossil assemblages. antarctic science 10, 269�285. bentley m.j., hodgson d.a., smith j.a., o cofaigh c., domack e.w., larter r.d., roberts s.j., brachfeld s., leventer a., hjort c., hillenbrand c.d. & evans j. 2009. mechanisms of holocene paleoenvironmental change in the antarctic peninsula region. the holocene 19, 51�69. boldt k.v., nittrouer c.a., hallet b., koppes m.n., forrest b.k., wellner j.s. & anderson j.b. 2013. modern rates of glacial sediment accumulation along a 158 s�n transect in fjords from the antarctic peninsula to southern chile. journal of geophysical research*earth surface 118, 2072�2088. burkhardt s., riebesell u. & zondervan i. 1999. effects of growth rate, co2 concentration, and cell size on the stable carbon isotope fractionation in marine phytoplankton. geochimica et cosmochimica acta 63, 3729�3741. carbotte s.m., ryan w.b.f., o’hara s., arko r., goodwillie a., melkonian a., weissel r.a. & ferrini v.l. 2007. antarctic multibeam bathymetry and geophysical data synthesis: an on-line digital data resource for marine geoscience research in the southern ocean. u.s. geological survey open-file report 2007-1047. short research paper 002. reston, va: u.s. geological survey. cook a.j., fox a.j., vaughan d.g. & ferrigno j.g. 2005. retreating glacier fronts on the antarctic peninsula over the past half-century. science 308, 541�544. difiore p.j., sigman d.m., karsh k.l., trull t.w., dunbar r.b. & robinson r.s. 2010. poleward decrease in the isotope effect of nitrate assimilation across the southern ocean. geophysical research letters 37, article no. l17601, doi: 10.1029/2010gl044090. domack e., leventer a., dunbar r., taylor f., brachfeld s. & sjunneskog c. 2001. chronology of the palmer deep site, antarctic peninsula; a holocene paleoenvironmental reference for the circum-antarctic. the holocene 11, 1�9. ducklow h.w., baker k., fraser w.r., martinson d.g., quetin l.b., ross r.m., smith r.c., stammerjohn s. & vernet m. 2007. marine pelagic ecosystems: the west antarctic peninsula. philosophical transactions of the royal society of london b 362, 67�94. garcı́a m., ercilla g., anderson j.b. & alonso b. 2008. new insights on the post-rift seismic stratigraphic architecture and sedimentary evolution of the antarctic peninsula margin (central bransfield basin). marine geology 251, 167�182. goldman j.c., mccarthy j.j. & peavey d.g. 1979. growth rate influence on the chemical composition of phytoplankton in oceanic waters. nature 279, 210�215. griffith t.w. & anderson j.b. 1989. climatic control of sedimentation in bays and fjords of the northern antarctic peninsula. marine geology 85, 181�204. a. barnard et al. palaeoclimate record from bransfield basin sediment core citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 hall b.l. 2007. late-holocene advance of the collins ice cap, king george island, south shetland islands. the holocene 17, 1253�1258. hall b.l., koffman t. & denton g.h. 2010. reduced ice extent on the western antarctic peninsula at 700�900 cal yr bp. geology 38, 635�638. henley s.f., annett a.l., ganeshram r.s., carson d.s., weston k., crosta x., tait a., dougans j., fallick a.e. & clarke a. 2012. factors influencing the stable carbon isotopic composition of suspended and sinking organic matter in the coastal antarctic sea ice environment. biogeosciences 9, 1137�1157. heroy d. & anderson j.b. 2005. ice sheet extent on the antarctic peninsula during the last glacial maximum (lgm)*insights from glacial geomorphology. geological society of america bulletin 117, 1497�1512. heroy d.c. & anderson j.b. 2007. radiocarbon constraints on antarctic peninsula ice sheet retreat following the last glacial maximum (lgm). quaternary science reviews 26, 3286�3297. heroy d.c., sjunneskog c. & anderson j.b. 2008. holocene climate change in the bransfield basin, antarctic peninsula; evidence from sediment and diatom analysis. antarctic science 20, 69�87. jørgensen s.e. & bendoricchio g. 2001. fundamentals of ecosystem modeling. amsterdam: elsevier. khim b.k., kim d., shin h.c. & kim d.y. 2005. stable carbon and nitrogen isotopes of sinking particles in the eastern bransfield strait (antarctica). ocean science journal 40, 167�176. koike i., holm-hansen o. & biggs d.c. 1986. inorganic nitrogen metabolism by antarctic phytoplankton with special reference to ammonium cycling. marine ecology progress series 30, 105�116. lomas m.w., rumbley c.j. & glibert p.m. 2000. ammonium release by nitrogen sufficient diatoms in response to rapid increases in irradiance. journal of plankton research 22, 2351�2366. lourey m.j., trull t.w. & sigman d.m. 2003. sensitivity of d15n of nitrate, surface suspended and deep sinking particulate nitrogen to seasonal nitrate depletion in the southern ocean. global biogeochemical cycles 17, 1�7. lu z., rickaby r.e.m., kennedy h., kennedy p., pancost r.d., shaw s., lennie a., wellner j. & anderson j.b. 2012. an ikaite record of late holocene climate at the antarctic peninsula. earth and planetary science letters 325�326, 108�115. lu z., rickaby r.e.m, wellner j., georg b., charnley n., anderson j.b. & hensen c. 2010. pore fluid modeling approach to identify recent meltwater signals on the west antarctic peninsula. geochemistry, geophysics, geosystems 11, 14�21. majewski w., wellner j.s., szczuciński w. & anderson j.b. 2012. holocene oceanographic and glacial changes recorded in maxwell bay, west antarctica. marine geology 326�328, 67�79. meredith m.p. & king j.c. 2005. rapid climate change in the ocean west of the antarctic peninsula during the second half of the 20th century. geophysical research letters 32, article no. l19604, doi: 10.1029/2005gl024042. meredith m.p., wallace m.i., stammerjohn s.e., renfrew i.a., clarke a., venables h.j., shoosmith d.r., souster t. & leng m.j. 2010. changes in the freshwater composition of the upper ocean west of the antarctic peninsula during the first decade of the 21st century. progress in oceanography 87, 127�143. meyers p.a. 1994. preservation of elemental and isotopic source identification of sedimentary organic matter. chemical geology 114, 289�302. meyers p.a. 1997. organic geochemical proxies of paleoceanographic, paleolimnologic, and paleoclimatic processes. organic geochemistry 27, 213�250. michalchuk b.r., anderson j.b., wellner j.s., manley p.l., majewski w. & bohaty s. 2009. holocene climate and glacial history of the northeastern antarctic peninsula: the marine sedimentary record from a long shaldril core. quaternary science reviews 28, 3049�3065. milliken k.t., anderson j.b., wellner j.s., bohaty s.m. & manley p.l. 2009. high-resolution climate history of maxwell bay, south shetland islands, antarctica. geological society of america bulletin 121, 1711�1725. minagawa m. & wada e. 1984. stepwise enrichment of 15n along food chains: further evidence and the relation between d15n and animal age. geochimica et cosmochimica acta 48, 1135�1140. mulvaney r., abram n.j., hindmarsh r.c.a., arrowsmith c., fleet l., triest j., sime l.c., alemany o. & foord s. 2012. recent antarctic peninsula warming relative to holocene climate and ice-shelf history. nature 489, 141�145. nielsen s.h.h., koc n. & crosta x. 2004. holocene climate in the atlantic sector of the southern ocean: controlled by insolation or oceanic circulation? geology 4, 317�320. prezelin b.b., hofmann e.e., mengelt c. & klinck j.m. 2000. the linkage between upper circumpolar deep water (ucdw) and phytoplankton assemblages on the west antarctic peninsula continental shelf. journal of marine research 58, 165�202. rau g.h., mearns a.j., young d.r., olson r.j., schafer h.a. & kaplan i.r. 1983. animal 12 c/ 13 c correlates with trophic level in pelagic food webs. ecology 64, 1314�1318. rau g.h., takahashi t. & des marais d.j. 1989. latitudinal variations in plankton d13c: implications for co2 and productivity in past oceans. nature 341, 516�518. redfield a.c. 1934. on the proportions of organic derivatives in seawater and their relation to the composition of plankton. in r.j. daniel (ed.): james johnson memorial volume. pp. 177�192. liverpool: liverpool university press. reynolds j.m. 1981. the distribution of mean annual temperatures in the antarctic peninsula. british antarctic survey bulletin 54, 123�133. simms a.r., milliken k.t., anderson j.b. & wellner j.s. 2011. the marine record of deglaciation of the south shetland palaeoclimate record from bransfield basin sediment core a. barnard et al. 12 (page number not for citation purpose) citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 islands, antarctica since the last glacial maximum. quaternary science reviews 30, 1538�1601. sjunneskog c. & taylor f. 2002. postglacial marine diatom record of the palmer deep, antarctic peninsula (odp leg 178, site 1098) 1. total diatom abundance. paleoceanography 17, article no. 8003, doi: 10.1029/2000pa000563. steig e.j., schneider d.p., rutherford s.d., mann m.e., comiso j.c. & shindell d.t. 2009. warming of the antarctic ice-sheet surface since the 1957 international geophysical year. nature 457, 459�462. stuiver m., reimer p.j. & reimer, r. w. 2005. calib v.6.0. accessed on the internet at http://calib.qub.ac.uk/calib/ on 1 november 2008. taylor f. & sjunneskog c. 2002. postglacial marine diatom record of the palmer deep, antarctic peninsula (odp leg 178, site 1098) 2. diatom assemblages. paleoceanography 17, article no. 1026, doi: 10.1029/2000pa000564. turner j., colwell s.r., marshall g.j., lachlan-cope t.a., carleton a.m., jones p.d., lagun v., reid p.a. & iagovkina s. 2005. antarctic climate change during the last 50 years. international journal of climatology 25, 279�294. vaughan d.g. & doake c.s.m. 1996. recent atmospheric warming and retreat of ice shelves on the antarctic peninsula. nature 379, 328�379. wefer g., fischer g., fuetterer d. & gersonde r. 1988. seasonal particle flux in the bransfield strait, antarctica. deep sea research part i 35, 891�898. willmott v., rampen s.w., domack e.w., canals m., damste j.s.s. & schouten s. 2009. holocene changes in probiscia diatom productivity in shelf waters of the northwestern antarctic peninsula. antarctic science 22, 3�10. a. barnard et al. palaeoclimate record from bransfield basin sediment core citation: polar research 2014, 33, 17236, http://dx.doi.org/10.3402/polar.v33.17236 13 (page number not for citation purpose) http://calib.qub.ac.uk/calib/ http://www.polarresearch.net/index.php/polar/article/view/17236 http://dx.doi.org/10.3402/polar.v33.17236 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice doi:10.3402/polar.v33.22963 r e s e a r c h / r e v i e w a r t i c l e contrasting strategies of resistance vs. tolerance to desiccation in two polar dipterans m.j. everatt,1 p. convey,2,3 m.r. worland,2 j.s. bale1 & s.a.l. hayward1 1 school of biosciences, university of birmingham, edgbaston, birmingham b15 2tt, uk 2 british antarctic survey, natural environment research council, high cross, madingley road, cambridge cb3 0et, uk 3 national antarctic research center, ips building, university malaya, 50603 kuala lumpur, malaysia keywords acclimation; dipteran; supercooling point; temperature; cross-tolerance. correspondence matthew john everatt, school of biosciences, university of birmingham, edgbaston, birmingham b15 2tt, uk. e-mail: mjemarue@hotmail.co.uk abstract low water availability is one of the principal stressors for terrestrial invertebrates in the polar regions, determining the survival of individuals, the success of species and the composition of communities. the arctic and antarctic dipterans heleomyza borealis and eretmoptera murphyi spend the majority of their biennial life cycles as larvae, and so are exposed to the full range of environmental conditions, including low water availability, over the annual cycle. in the current study, the desiccation resistance and desiccation tolerance of larvae were investigated, as well as their capacity for crosstolerance to temperature stress. larvae of h. borealis showed high levels of desiccation resistance, only losing 6.9% of their body water after 12 days at 98.2% relative humidity (rh). in contrast, larvae of e. murphyi lost 46.7% of their body water after 12 days at the same rh. survival of e. murphyi larvae remained high in spite of this loss (�80% survival). following exposure to 98.2% rh, larvae of e. murphyi showed enhanced survival at �188c for 2 h. the supercooling point of larvae of both species was also lowered following prior treatment at 98.2% rh. cross-tolerance to high temperatures (37 or 38.58c) was not noted following desiccation in e. murphyi, and survival even fell at 378c following a 12-day pre-treatment. the current study demonstrates two different strategies of responding to low water availability in the polar regions and indicates the potential for cross-tolerance, a capacity which is likely to be beneficial in the ever-changing polar climate. insects, which are largely of small size, have a high surface area to volume ratio and are vulnerable to water loss (gibbs et al. 1997). injuries resulting from the loss of water include protein denaturation and unwanted macromolecular interactions, crystalline to gel membrane phase transitions, oxidative damage and mechanical stress (danks 2000). in order to protect against these injuries, invertebrates generally adopt one of two strategies, desiccation resistance or desiccation tolerance. the capacity to prevent water loss from the body (desiccation resistance) varies greatly among invertebrates and has led to three species classifications, namely hygric species, which have little or no control over their water loss, and transitional and mesic species, which are increasingly able to regulate the loss of body water (danks 2000). the mesic status of invertebrates like the antarctic mite alaskozetes antarcticus is largely achieved through lowered cuticular permeability (e.g., benoit, yoder et al. 2007), though the regulation of water is also achieved in other invertebrates using methods of freezing (convey 1992), membrane alteration and metabolic suppression (michaud et al. 2008) and/or specialized respiration (danks 2000). in hygric species, the loss of water is tolerated. dendrobaena octaedra (earthworm) cocoons (holmstrup & zachariassen 1996) and larvae of the antarctic dipteran belgica antarctica (hayward et al. 2007) are able to endure �75% loss of their water content, while some insects, such as the dipteran polypedilum vanderplaanki and many polar research 2014. # 2014 m.j. everatt et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 22963, http://dx.doi.org/10.3402/polar.v33.22963 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22963 http://dx.doi.org/10.3402/polar.v33.22963 nematodes and tardigrades, are able to survive the loss of virtually all their osmotically active water, employing the tactic of anhydrobiosis (crowe & madin 1975; wharton & barclay 1993; watanabe et al. 2002; wharton 2003, 2011; hengherr et al. 2010). molecular mechanisms underpinning desiccation tolerance include the accumulation of polyhydric alcohols and sugars (benoit, lopezmartinez et al. 2007; hengherr et al. 2008), the utilization of hsp and lea proteins (bahrndorff et al. 2009; lopezmartinez et al. 2009; popovic et al. 2011), shifts in metabolism (danks 2000; li et al. 2009), membrane remodelling (lopez-martinez et al. 2009), oxidative damage repair (lopez-martinez et al. 2008) and cytoskeletal reorganization (li et al. 2009; lopez-martinez et al. 2009). low water availability is seen as being one of two principal stressors to terrestrial invertebrates in the polar regions, with the other being low temperature (cannon & block 1988; convey 1996; strathdee & bale 1998; block et al. 2009). in winter, water is locked up as ice and is inaccessible to invertebrates (block et al. 2009), while in summer, evaporation of meltwater can lead to drought (kennedy 1993). in some areas, such as the mcmurdo dry valleys, soil water content can be as little as 2% (treonis & wall 2005). the antarctic dipteran eretmoptera murphyi and the high-arctic dipteran heleomyza borealis also experience aridity in their respective habitats. the larval stages of these two species comprise the majority of the life cycle duration, and thus experience the full spectra of environmental conditions over the annual cycle (convey & block 1996; worland et al. 2000). eretmoptera murphyi is locally highly abundant in the sub-antarctic island of south georgia and, since its introduction onto signy island (maritime antarctic) in the 1960s, it has spread to occupy an area �2000 m 2 , with densities as high as 410 000 ind. m �2 (hughes & worland 2010). worland (2010) has shown that e. murphyi larvae possess good desiccation tolerance, but low desiccation resistance. heleomyza borealis is also abundant at certain high-arctic sites when found in association with bird colonies, but its desiccation tolerance has not been assessed thoroughly. because injuries to invertebrates, such as protein impairment and loss of membrane fluidity, result from desiccation as well as from other stresses like low temperature, the physiological adaptations induced in response to these stresses are analogous, or at least complementary (ring & danks 1998; bayley et al. 2001). for example, the desaturation of membranes, upregulation of heat shock proteins and the accumulation of polyols and sugars occur after both desiccation and low temperature treatments (bayley et al. 2001; holmstrup et al. 2002; bahrndorff et al. 2007; benoit et al. 2009). it therefore follows that a sub-lethal desiccation exposure can potentially afford protection for an invertebrate subsequently exposed to low temperatures. this phenomenon is termed cross-tolerance and has been observed in a number of organisms, though primarily in diptera and collembola (e.g., holmstrup et al. 2002; elnitsky et al. 2008; levis et al. 2012). in the collembolan megaphorura arctica desiccation in the presence of ice lowers the supercooling point (scp) to such an extent that the collembolan is able to survive the low temperatures of the arctic winter (worland et al. 1998). this strategy, termed cryoprotective dehydration, is now seen to be fairly common, having been described in an increasing number of invertebrates (e.g., pedersen & holmstrup 2003; elnitsky et al. 2008; smith et al. 2008; sørensen & holmstrup 2011). cross-tolerance also works independently of the scp. in the freeze-tolerant dipteran b. antarctica survival was improved by 90% at �108c following 48 h at 98% relative humidity (rh) and by 60% at �158c following the loss of 50% of its body water (benoit et al. 2009). invertebrates that experience complete desiccation or anhydrobiosis are also conferred improved low temperature tolerance, and the extent to which it is improved is usually greater than in partially desiccated animals like b. antarctica (e.g., ramløv & westh 1992; sømme & meier 1995; shuker 2001). climate change is leading to warmer summers in the polar regions, with evidence of increasing exposure to drought (convey et al. 2003; convey et al. 2009; turner et al. 2009). exploration of cross-tolerance between desiccation and low and high temperature in two additional dipteran species, therefore, provides further insight into how polar terrestrial invertebrates tolerate extreme conditions currently and may indicate how they will cope with climate warming in future. materials and methods insect collection and storage conditions summer acclimatized individuals of heleomyza borealis were collected from the moss-covered slopes at krykkjefjellet and blomstrandhalvøya, near ny-ålesund, spitsbergen, svalbard (78855?n, 11856?e) in august 2011. summer acclimatized individuals of eretmoptera murphyi were collected from soil and moss on signy island (608s, 458w) close to the british antarctic survey signy research station between january and march 2012. they were transported to the university of birmingham under refrigerated conditions and then held in plastic boxes containing substratum from the site of collection at 48c desiccation in polar diptera m.j. everatt et al. 2 (page number not for citation purpose) citation: polar research 2014, 33, 22963, http://dx.doi.org/10.3402/polar.v33.22963 http://www.polarresearch.net/index.php/polar/article/view/22963 http://dx.doi.org/10.3402/polar.v33.22963 (0:24 l:d). the duration of travel was approximately two days from the arctic and two months from the antarctic. numbers of h. borealis were limited and hence it was not possible to assess for cross-tolerance to high and low temperatures, except with respect to their scps. water balance and desiccation tolerance bayley & holmstrup (1999) highlighted the importance of performing desiccation experiments at more ecologically relevant rh values, and in particular those close to the wilting point of plants (ca. 98.9% rh). the specific rh of 98.2% used here was produced using 150 ml of nacl solution (31.60 g nacl l �1 ) in a plastic container. the rh was verified as being stable using a hygrochron temperature and humidity logger ibutton (maxim, san jose, ca, usa). controls were maintained at 100% rh using purified water and were given access to water. dipteran larvae were placed in small glass containers, covered with nylon gauze, which were then placed inside the plastic containers, and sealed with a tight fitting lid. following raoult’s law, the air inside the closed system quickly equilibrated with the aqueous solution used. three replicates of 10 individuals of each species were removed from 98.2% rh at set intervals over a 12-day period (6 h, 2, 4, 8 and 12 days). dipteran larvae were subsequently transferred into plastic universal tubes containing moist plaster of paris and given substrate and water. survival, defined as larvae which either moved spontaneously or in response to gentle contact stimulus, was assessed 72 h after treatment. the larvae were also weighed prior to desiccation, upon removal from each desiccation treatment, and following drying to constant mass at 608c over 24 h. from these values, initial water content and percentage water loss or gain were calculated (see hayward et al. 2007). desiccation induced low temperature tolerance effect of desiccation on the scp. individuals of h. borealis and e. murphyi were held at 98.2% rh for either 6 h, 2, 4, 8 or 12 days (only 12 days for h. borealis) prior to experimental treatment. fifteen larvae were placed in contact with a thermocouple, within beem capsules, in glass test tubes plugged with sponge, inside an alcohol bath (haake phoenix ii c50p, fisher scientific uk ltd, loughborough, uk). larvae were subsequently cooled from 4 to �308c at 0.5 min�1. scps, defined as the temperature at the onset of the freezing exotherm, were identified using an eight channel datalogger interfaced to a computer and recorded using picolog recorder software (pico technology limited, st. neots, uk; see hawes et al. 2006). lower discriminating temperature. the temperature at which 10�20% survival occurred (lee et al. 1987) was determined by cooling three replicates of 10 larvae at 0.28c min�1 to progressively lower sub-zero temperatures ( �15 to �198c) for 2 h, before being re-warmed to the rearing temperature (48c) at the same rate. larvae were placed in eppendorf tubes, inside glass test tubes plugged with sponge, in an alcohol bath prior to each experimental treatment. control groups were handled, and exposed, in the same way at 48c. the temperature experienced by the larvae was measured by placing a thermocouple within an identical eppendorf tube into one of the glass test tubes. at the end of each experimental treatment, the larvae were rapidly transferred (over ice) from the eppendorf tubes into plastic universal tubes containing moist plaster of paris and substratum, and returned to the rearing conditions. survival was assessed as described previously. the highest temperature at which survival was between 10 and 20% after 72 h recovery was defined as the discriminating temperature. effect of desiccation on low temperature tolerance. larvae of e. murphyi only were held at 98.2% rh for 6 h, 2, 4, 8 or 12 days prior to experimental treatment. three replicates of 10 larvae were subsequently cooled at 0.28c min�1 to the discriminating temperature and held for 2 h before being re-warmed to the rearing temperature at the same rate. larvae collection and handling, controls, thermocouple use, recovery and survival assessment were as described previously. desiccation-induced heat tolerance higher discriminating temperature. the temperature at which 10�20% survival occurred was determined by warming three replicates of 10 individuals at 0.28c min �1 to progressively higher temperatures (30�408c) for 2 h, before being re-cooled to the rearing temperature at the same rate. larvae collection and handling, controls, thermocouple use, recovery and survival assessment were as described previously. the lowest temperature at which survival was between 10 and 20% after 72 h recovery was defined as the discriminating temperature. the lowest temperature at which survival was between 80 and 90% was also used to assess whether survival was lowered by a prior desiccation exposure. effect of desiccation on high temperature tolerance. larvae of e. murphyi were held at 98.2% rh for 6 h, 2, 4, 8 and 12 days prior to experimental m.j. everatt et al. desiccation in polar diptera citation: polar research 2014, 33, 22963, http://dx.doi.org/10.3402/polar.v33.22963 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22963 http://dx.doi.org/10.3402/polar.v33.22963 treatment. three replicates of 10 larvae were subsequently warmed at 0.28c min�1 to the discriminating temperature and the 80�90% survival temperature. larvae were held for 2 h and cooled to the rearing temperature at the same rate. larvae collection and handling, controls, thermocouple use, recovery and survival assessment were as described previously. statistical analysis the kolmogorov-smirnov test was used to check for normality in the survival, scp and percentage water loss data. normally distributed data were analysed using analysis of variance (anova) and tukey’s multiple range test; data that were not normally distributed were analysed using the kruskal-wallis test. results water balance and desiccation tolerance larvae of heleomyza borealis were significantly more desiccation resistant than those of eretmoptera murphyi (fig. 1). after 12 days, larvae of h. borealis had lost only 6.9% of their water content, as compared with 46.7% in larvae of e. murphyi. water loss rate was not constant in larvae of e. murphyi; between 2 and 4 days, they regained 13.6% of their initial water content, before losing water rapidly again thereafter. survival following 6 h, 2 days, 4 days, 8 days and 12 days at 98.2% rh was high in larvae of both h. borealis and e. murphyi, and was not significantly different from survival in the control (fig. 2). desiccation-induced cold tolerance effect of desiccation on the scp. prior exposure to 98.2% rh significantly lowered the scp in larvae of both species (table 1). in larvae of h. borealis the scp fell by 1.68c after 12 days at 98.2% rh, while in larvae of e. murphyi the scp fell by up to 2.58c. lower discriminating temperature and the effect of desiccation on low temperature tolerance. survival of e. murphyi larvae declined gradually following exposure to progressively lower temperatures (fig. 3a). the discriminating temperature (20% survival) was determined to be �188c. at this temperature, survival of e. murphyi larvae was raised following all acclimation treatments (6 h, 2 days, 4 days, 8 days and 12 days) at 98.2% rh (fig. 3b). the increase in survival was significant following 4 days. desiccation-induced heat tolerance higher discriminating temperature and the effect of desiccation on high temperature tolerance. survival of e. murphyi larvae remained at 100% up to 358c, but declined rapidly at temperatures near to the upper lethal temperature (ult), falling by 80% between 37 and 408c (fig. 4a). the discriminating temperatures were determined to be 38.5 and 378c, giving 20 and 80% survival, respectively. at 378c, survival of e. murphyi larvae was unchanged at around 80% following 2, 4 and 8 days at 98.2% rh, but declined to 55% after 12 days (fig. 4b). there was also no significant difference between non-acclimated and acclimated larvae of e. murphyi at 38.58c. fig. 1 percentage water loss or gain of larvae of h. borealis and e. murphyi following exposure to 98.2% relative humidity (rh) for 6 h, 2 days, 4 days, 8 days and 12 days. means9standard error of the mean are presented for three replicates of 10 individuals. means with the same letter are not significantly different within each species group at pb0.05 (tukey’s multiple range test). fig. 2 survival (%) of larvae of h. borealis and e. murphyi following exposure to 98.2% relative humidity (rh) for 6 h, 2 days, 4 days, 8 days and 12 days. means9standard error of the mean are presented for three replicates of 10 individuals. survival was assessed 72 h after treatment. means with the same letter are not significantly different from the control within each species group at pb0.05 (tukey’s multiple range test). desiccation in polar diptera m.j. everatt et al. 4 (page number not for citation purpose) citation: polar research 2014, 33, 22963, http://dx.doi.org/10.3402/polar.v33.22963 http://www.polarresearch.net/index.php/polar/article/view/22963 http://dx.doi.org/10.3402/polar.v33.22963 discussion desiccation resistance water availability is limited for much of the year in the arctic and antarctic (strathdee & bale 1998; block et al. 2009), and polar terrestrial invertebrates respond with one of two strategies, desiccation resistance or desiccation tolerance. our data suggest that the arctic dipteran heleomyza borealis responds through desiccation resistance, while the antarctic species eretmoptera murphyi tolerates substantial desiccation (figs. 1, 2). the rate of water loss in e. murphyi was seven times more rapid than in h. borealis and was similar to that reported by worland (2010) at 88% rh. the closely related dipteran belgica antarctica which also inhabits the maritime antarctic, likewise shows a high rate of water loss. when exposed to 98% rh, larvae of this dipteran took around 5 days to lose 50%, and 8�10 days to lose over 60%, of their body water (benoit, lopez-martinez et al. 2007). there is therefore a clear difference in the level of desiccation resistance between h. borealis and the antarctic diptera e. murphyi and b. antarctica. the physiology of the cuticular layer between these species provides a possible, albeit unexplored, explanation for the difference, and lowered cuticular permeability is a widespread adaptation that invertebrates use to raise their desiccation resistance (danks 2000). invertebrates achieve this by increasing the number and/or length of hydrocarbons or hydrophobic molecules in the wax layer surrounding their cuticle, resulting in tighter packing and a greater reduction of water loss rate (gibbs et al. 1997; benoit, yoder et al. 2007; speight et al. 2008). benoit, lopez-martinez et al. (2007) showed that the length of hydrocarbons increased in desiccated larvae of b. antarctica, but this change was only slight and there was no change in the number of hydrocarbons. eretmoptera murphyi is closely related to b. antarctica (allegrucci et al. 2006; allegrucci et al. 2012) and may therefore possess similar physiological adaptations. we speculate that the initial composition and change in the cuticle layer is more biased towards a greater number and length of hydrocarbons in h. borealis than either antarctic dipteran. differences in melanization between the two diptera may also offer an explanation for the differing levels of resistance in the current study, as has been shown between drosophila (parkash, rajpurohit et al. 2008; parkash, ramniwas et al. 2008; parkash et al. 2009; parkash et al. 2012; ramniwas et al. 2013). it should also be noted that 98.2% rh may be a sufficiently high humidity that larvae of h. borealis are able to absorb water from the atmosphere. this may also underlie our observation that, between 2 and 4 days’ exposure at 98.2% rh, larvae of e. murphyi exhibited reduced water loss and even rehydration. rehydration has also been observed in other species. in the collembolan folsomia candida nearly all of the water lost initially at table 1 h. borealis and e. murphyi larval supercooling points (scps) following exposure to 98.2% relative humidity (rh) for 6 h, 2 days, 4 days, 8 days and 12 days (only 12 days for h. borealis). means9standard error of the mean are presented for 15 replicates. asterisks indicate a treatment significantly different from the control (0 h) at pb0.05 (tukey’s multiple range test). scp (8c) species 0 h 6 h 2 days 4 days 8 days 12 days h. borealis �7.7090.28 � � � � �9.2990.38* e. murphyi �5.0590.29 �6.1690.11 �6.2190.29 �5.3690.40 �7.5290.22* �6.7490.46* fig. 3 survival (%) of larvae of e. murphyi (a) after exposure to progressively lower sub-zero temperatures ( �15 to �198c) for 2 h, and (b) after exposure to �188c, following prior exposure to 98.2% relative humidity (rh) for 6 h, 2 days, 4 days, 8 days and 12 days. means9standard error of the mean are presented for three replicates of 10 individuals. survival was assessed 72 h after treatment. means with the same letter are not significantly different at pb0.05 (tukey’s multiple range test). m.j. everatt et al. desiccation in polar diptera citation: polar research 2014, 33, 22963, http://dx.doi.org/10.3402/polar.v33.22963 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22963 http://dx.doi.org/10.3402/polar.v33.22963 98.2% rh was recovered within 5�7 days, despite being continually held at 98.2% rh (bayley & holmstrup 1999). as confirmed by microarray, this recovery was supplemented by accumulating and synthesising myoinositol, glucose and trehalose, which allowed the collembolan to become hyperosmotic to the environment and absorb moisture (timmermans et al. 2009). an analogous response may be present in e. murphyi. however, such a response has not been observed in the closely related b. antarctica, which was unable to absorb water from the atmosphere at any rh, except complete saturation, i.e., 100% rh (benoit, lopez-martinez et al. 2007; hayward et al. 2007). desiccation tolerance heleomyza borealis showed �90% survival following 12 days of desiccation (fig. 2). however, because water loss was so slight, even after 12 days at 98.2% rh, larvae cannot be said to have tolerated desiccation. instead, it suggests that larvae of h. borealis are able to survive well under ecologically relevant relative humidities using a desiccation resistance strategy. conversely, larvae of e. murphyi tolerated desiccation, having shown considerable water loss, but also survival, following 12 days at 98.2% rh (fig. 2). belgica antarctica also principally uses a desiccation tolerance strategy and has been shown to survive well following a 75% loss of initial water content (benoit, lopez-martinez et al. 2007; hayward et al. 2007). one means of tolerating desiccation is through possessing high initial water content, as an organism must subsequently lose more water before reaching a point at which damage occurs or energy intensive mechanisms are induced (hayward et al. 2007). this argument is reinforced by the increased water content observed in selected desiccation tolerant lines of drosophila melanogaster (gibbs 1997). in e. murphyi larvae, the initial water content was high, averaging 74.3% (73.28� 75.40%) of body mass (benoit et al. 2009). we did not assess osmotically active water in this study, though b. antarctica is known to have very high osmotically active water content relative to temperate species (hayward et al. 2007). once considerable water loss does occur, as was the case in the current study, the potential for injury is great and an organism must adapt accordingly. injuries that result from desiccation include protein denaturation and unwanted macromolecular interactions (benoit et al. 2009), crystalline to gel phase transitions (hazel 1995), oxidative damage (lopezmartinez et al. 2008) and mechanical stress (li et al. 2009). the responses of b. antarctica in this regard have been particularly well studied. larvae accumulate glycerol and trehalose, which are suggested as being replacements for lost water and/or an aid to the production of amorphous sugar glasses (danks 2000; benoit, lopezmartinez et al. 2007; michaud et al. 2008; bahrndorff et al. 2009; benoit et al. 2009; hengherr et al. 2009; clarke et al. 2013). protein denaturation is also ameliorated via the up-regulation of hsps in response to desiccation (lopez-martinez et al. 2009; teets et al. 2012), and the fluidity of the membrane maintained using enzymes such as d9 fad desaturase (lopezmartinez et al. 2009). further physiological mechanisms induced in response to desiccation include oxidative damage repair through the accumulation of antioxidants (lopez-martinez et al. 2008), the minimization of mechanical stress via the restructuring of the cytoskeleton (li et al. 2009), the inhibition of apoptosis through the regulation of autophagy and the suppression of metabolism (teets et al. 2012). larvae of b. antarctica therefore fig. 4 survival (%) of larvae of e. murphyi (a) after exposure to progressively higher temperatures (30�408c) for 2 h and (b) after exposure to 37 or 38.58c, following prior exposure to 98.2% relative humidity (rh) for 6 h, 2 days, 4 days, 8 days and 12 days. means 9standard error of the mean are presented for three replicates of 10 individuals. survival was assessed 72 h after treatment. means with the same letter are not significantly different across temperature treatments (a) and between temperature treatments (b) at pb0.05 (tukey’s multiple range test). desiccation in polar diptera m.j. everatt et al. 6 (page number not for citation purpose) citation: polar research 2014, 33, 22963, http://dx.doi.org/10.3402/polar.v33.22963 http://www.polarresearch.net/index.php/polar/article/view/22963 http://dx.doi.org/10.3402/polar.v33.22963 possess a suite of physiological responses against injuries resulting from desiccation. it is possible that e. murphyi possesses similar physiological adaptations that underlie its high level of desiccation tolerance. indeed, the capacity to which they respond to temperature is very similar (lee et al. 2006; everatt et al. 2012). desiccation-induced cross-tolerance low temperatures. survival of e. murphyi at �188c was significantly raised following desiccation at 98.2% rh (fig. 3b). greater survivorship at low temperatures, following pre-exposure to unsaturated conditions, has also been observed for a number of other invertebrates, including b. antarctica (benoit et al. 2009) and the springtails cryptopygus antarcticus (elnitsky et al. 2008; everatt, worland et al. 2013) and folsomia candida (holmstrup et al. 2002). cross-tolerance is thought to occur between desiccation and low temperature because injuries that result from the two stresses are similar. consequently, the physiological mechanisms induced in response to desiccation and low temperatures are often analogous (e.g., bayley et al. 2001), and act in concert to give greater protection. even a mild desiccation treatment resulting in 6�10% water loss has been shown to confer significant gains in cold tolerance in the goldenrod gall fly, eurosta solidaginis (levis et al. 2012). interestingly, survival of �188c was highest after 4 days at 98.2% rh and not after longer durations of 8 and 12 days (fig. 3b). this corresponds with the time period at which larvae of e. murphyi exhibited rehydration (fig. 1), suggesting physiological processes associated with rehydration provide cold tolerance, and that these are additive to the protection provided by those solely concerned with desiccation tolerance. an effect on the scp was also observed in the current study for both h. borealis and e. murphyi. following a pre-exposure to 98.2% rh, the scp was significantly reduced (table 1). both dipteran species are freezetolerant and it is therefore preferable for extracellular ice formation to take place at higher sub-zero temperatures, as it occurs more slowly and decreases the chance of tissue damage (worland & block 1999). the lowering of the scp in h. borealis and e. murphyi was therefore more likely a by-product of, rather than an adaptation to, desiccation. water loss passively increases the concentration of solutes already present and results in the colligative lowering of the scp (e.g., holmstrup & zachariassen 1996). the dipteran larvae were also starved during the desiccation treatments and, during periods of starvation, ice-nucleating gut contents may be removed, reducing the likelihood of ice formation (sømme & block 1982; cannon & block 1988). worland et al. (2006) also reported that time spent without access to food on water surfaces lowered the scp of the collembolan ceratophysella denticulata. high temperatures. prior exposure to desiccation at 98.2% rh had either no effect or a negative effect on the heat tolerance of e. murphyi larvae (fig. 4b). unlike low temperatures, injuries incurred as a result of high temperatures are dissimilar to those of desiccation, and physiological defences mounted in response to desiccation are therefore also different, and could even be conflicting. consequently, little protection is afforded by prior acclimation to desiccation. a similar response has been observed in nematodes (holmstrup & zachariassen 1996) and collembola (everatt, worland et al. 2013). however, improved heat tolerance has been noted in other invertebrates, particularly those which are anhydrobiotic (e.g., hinton 1951, 1960; sakurai et al. 2008). it is speculated that anhydrobiotic organisms, because of their tendency to vitrify, are less susceptible to injuries in general and that conflicting injuries are therefore less important. while this explanation is appropriate for anhydrobiotic organisms, the same is not true of partially desiccated organisms, which tend not to vitrify. at 308c, heat tolerance was improved in partially desiccated larvae of b. antarctica following pre-exposure to 0, 75 and 98% rh (benoit et al. 2009). in this instance, the up-regulation of heat shock proteins and the accumulation of trehalose were suggested as being possible explanations for the enhanced heat tolerance by overcompensating for any opposing injuries. the heat tolerance of e. murphyi has been little explored, except in a study by everatt et al. (2014), which showed larval survival up to 398c for 1 h. in the current study, larvae of e. murphyi showed 100% survival up to 358c and also survived temperatures as high as 398c for the longer period of 2 h (fig. 4). larvae of b. antarctica are likewise able to survive temperatures above 308c (benoit et al. 2009). although these organisms rarely, if ever, experience temperatures nearing 30 or even 258c, their heat tolerance is not surprising. a number of other studies, including those by deere et al. (2006), everatt, convey et al. (2013), sinclair et al. (2006) and slabber et al. (2007) have similarly shown appreciable heat tolerance in polar invertebrates. such findings are consistent with the ‘‘thermal sensitivity hypothesis,’’ which states that the thermal sensitivity of invertebrates to a temperature rise declines with increasing latitude (addo-bediako et al. 2000; deutsch et al. 2008). conclusion the arctic and antarctic are similar in that they include both cold and arid landscapes. however, the diptera of m.j. everatt et al. desiccation in polar diptera citation: polar research 2014, 33, 22963, http://dx.doi.org/10.3402/polar.v33.22963 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22963 http://dx.doi.org/10.3402/polar.v33.22963 these regions, based on the evidence presented here, have not adapted similarly. two strategies of living in a dry environment have been identified. the arctic dipteran heleomyza borealis utilizes desiccation resistance, while the antarctic dipteran eretmoptera murphyi principally uses desiccation tolerance. divergence between antarctic and arctic invertebrates has also been shown between belgica antarctica and megaphorura arctica, which utilize distinct molecular mechanisms in response to desiccation (teets et al. 2012). desiccation was found to induce cross-tolerance to low temperatures, but not high temperatures, in e. murphyi. an ability to acclimate in this way would likely be beneficial in the variable climates typical of polar terrestrial habitats, where low temperature and low water availability are commonly encountered simultaneously. acknowledgements mje was funded by the natural environment research council (rrbn15266) and was supported by the british antarctic survey and the university of birmingham. pc is supported through natural environment research council core funding to the british antarctic survey’s ecosystems programme. this paper also contributes to the evolution and biodiversity in antarctica research programme of the scientific committee on antarctic research. references addo-bediako a., chown s.l. & gaston k.j. 2000. thermal tolerance, climatic variability and latitude. proceedings of the royal society of london b 267, 739�745. allegrucci g., carchini g., convey p. & sbordoni v. 2012. evolutionary geographic relationships among orthocladine chironomid midges from maritime antarctic and subantarctic islands. biological journal of the linnaean society 106, 258�274. allegrucci g., carchini g., todisco v., convey p. & sbordoni v. 2006. a molecular phylogeny of antarctic chironomidae and its implications for biogeographical history. polar biology 29, 320�326. bahrndorff s., petersen s.o., loeschcke v., overgaard j. & holmstrup m. 2007. differences in cold and drought tolerance of high arctic and sub-arctic populations of megaphorura arctica tullberg 1876 (onychiuridae: collembola). cryobiology 55, 315�323. bahrndorff s., tunnacliffe a., wise m.j., mcgee b., holmstrup m. & loeschcke v. 2009. bioinformatics and protein expression analyses implicate lea proteins in the drought response of collembola. journal of insect physiology 55, 210�217. bayley m. & holmstrup m. 1999. water vapor absorption in arthropods by accumulation of myoinositol and glucose. science 285, 1909�1911. bayley m., petersen s.o., knigge t., köhler h.-r. & holmstrup m. 2001. drought acclimation confers cold tolerance in the soil collembolan folsomia candida. journal of insect physiology 47, 1197�1204. benoit j.b., lopez-martinez g., elnitsky m.a., lee r.e. & denlinger d.l. 2009. dehydration-induced cross tolerance of belgica antarctica larvae to cold and heat is facilitated by trehalose accumulation. comparative biochemistry and physiology a 152, 518�523. benoit j.b., lopez-martinez g., michaud m.r., elnitsky m.a., lee r.e. & denlinger d.l. 2007. mechanisms to reduce dehydration stress in larvae of the antarctic midge, belgica antarctica. journal of insect physiology 53, 656�667. benoit j.b., yoder j.a., lopez-martinez g., elnitsky m.a., lee r.e. & denlinger d.l. 2007. adaptations for the maintenance of water balance by three species of antarctic mites. polar biology 31, 539�547. block w., lewis smith r.i. & kennedy a.d. 2009. strategies of survival and resource exploitation in the antarctic fellfield ecosystem. biological reviews of the cambridge philosophical society 84, 449�484. cannon r.j. & block w. 1988. cold tolerance of microarthropods. biological reviews of the cambridge philosophical society 63, 23�77. clarke a., morris g.j., fonseca f., murray b.j., acton e. & price h.c. 2013. a low temperature limit for life on earth. plos one 8, e66207. convey p. 1992. aspects of the biology of the midge, eretmoptera murphyi schaeffer (diptera: chironomidae), introduced to signy island, maritime antarctic. polar biology 12, 653�657. convey p. 1996. the influence of environmental characteristics on life history attributes of antarctic terrestrial biota. biological reviews 71, 191�225. convey p., bindschadler r., di prisco g., fahrbach e., gutt j., hodgson d.a., mayewski p.a., summerhayes c.p. & turner j. 2009. antarctic climate change and the environment. antarctic science 21, 541�563. convey p. & block w. 1996. antarctic diptera: ecology, physiology and distribution. european journal of entomology 93, 1�13. convey p., block w. & peat h.j. 2003. soil arthropods as indicators of water stress in antarctic terrestrial habitats? global change biology 9, 718�730. crowe j.h. & madin k.a.c. 1975. anhydrobiosis in nematodes: evaporative water loss and survival. journal of experimental zoology 193, 323�334. danks h. 2000. dehydration in dormant insects. journal of insect physiology 46, 837�852. deere j.a., sinclair b.j., marshall d.j. & chown s.l. 2006. phenotypic plasticity of thermal tolerances in five oribatid mite species from sub-antarctic marion island. journal of insect physiology 52, 693�700. desiccation in polar diptera m.j. everatt et al. 8 (page number not for citation purpose) citation: polar research 2014, 33, 22963, http://dx.doi.org/10.3402/polar.v33.22963 http://www.polarresearch.net/index.php/polar/article/view/22963 http://dx.doi.org/10.3402/polar.v33.22963 deutsch c.a., tewksbury j.j., huey r.b., sheldon k.s., ghalambor c.k., haak d.c. & martin p.r. 2008. impacts of climate warming on terrestrial ectotherms across latitude thermal safety margin. proceedings of the national academy of sciences of the united states of america 105, 6668�6672. elnitsky m.a., hayward s.a.l., rinehart j.p., denlinger d.l. & lee r.e. 2008. cryoprotective dehydration and the resistance to inoculative freezing in the antarctic midge, belgica antarctica. the journal of experimental biology 211, 524�530. everatt m.j., convey p., worland m.r., bale j.s. & hayward s.a.l. 2013. heat tolerance and physiological plasticity in the antarctic collembolan, cryptopygus antarcticus, and mite, alaskozetes antarcticus. journal of thermal biology 38, 264�271. everatt m.j., convey p., worland m.r., bale j.s. & hayward s.a.l. 2014. are the antarctic dipteran, eretmoptera murphyi, and arctic collembolan, megaphorura arctica, vulnerable to rising temperatures? bulletin of entomological research. everatt m.j., worland m.r., bale j.s., convey p. & hayward s.a.l. 2012. pre-adapted to the maritime antarctic? rapid cold hardening of the midge, eretmoptera murphyi. journal of insect physiology 58, 1104�1111. everatt m.j., worland m.r., convey p., bale j.s. & hayward s.a.l. 2013. the impact of salinity on survival and temperature tolerance of the antarctic collembolan, cryptopygus antarcticus. physiological entomology 38, 202�210. gibbs a.g., chippindale a.k. & rose m.r. 1997. physiological mechanisms of evolved desiccation resistance in drosophila melanogaster. the journal of experimental biology 200, 1821� 1832. hawes t.c., couldridge c.e., bale j.s., worland m.r. & convey p. 2006. habitat temperature and the temporal scaling of cold hardening in the high arctic collembolan, hypogastrura tullbergi (schäffer). ecological entomology 31, 450�459. hayward s.a.l., rinehart j.p., sandro l.h., lee r.e. & denlinger d.l. 2007. slow dehydration promotes desiccation and freeze tolerance in the antarctic midge belgica antarctica. the journal of experimental biology 210, 836�844. hazel j.r. 1995. thermal adaptation in biological membranes: is homeoviscous adaptation the explanation? annual review of physiology 57, 19�42. hengherr s., heyer a.g., köhler h.-r. & schill r.o. 2008. trehalose and anhydrobiosis in tardigrades*evidence for divergence in responses to dehydration. the febs journal 275, 281�288. hengherr s., reuner a., brümmer f. & schill r.o. 2010. ice crystallization and freeze tolerance in embryonic stages of the tardigrade milnesium tardigradum. comparative biochemistry and physiology a 156, 151�155. hengherr s., worland m.r., reuner a., brümmer f. & schill r.o. 2009. freeze tolerance, supercooling points and ice formation: comparative studies on the subzero temperature survival of limno-terrestrial tardigrades. the journal of experimental biology 212, 802�807. hinton h.e. 1951. a new chironomid from africa, the larvae of which can be dehydrated without injury. proceedings of the zoological society (calcutta) 121, 371�380. hinton h.e. 1960. cryptobiosis in the larva of polypedilum vanderplanki hint (chironomidae). journal of insect physiology 5, 286�300. holmstrup m., hedlund k. & boriss h. 2002. drought acclimation and lipid composition in folsomia candida: implications for cold shock, heat shock and acute desiccation stress. journal of insect physiology 48, 961�970. holmstrup m. & zachariassen k.e. 1996. physiology of cold hardiness in earthworms. comparative biochemistry and physiology a 115, 91�101. hughes k.a. & worland m.r. 2010. spatial distribution, habitat preference and colonization status of two alien terrestrial invertebrate species in antarctica. antarctic science 22, 221�231. kennedy a.d. 1993. water as a limiting factor in the antarctic terrestrial environment: a biogeographical synthesis. arctic antarctic and alpine research 25, 308�315. lee r.e., chen c.p. & denlinger d.l. 1987. a rapid coldhardening process in insects. science 238, 1415�1417. lee r.e., elnitsky m.a., rinehart j.p., hayward s.a.l., sandro l.h. & denlinger d.l. 2006. rapid cold-hardening increases the freezing tolerance of the antarctic midge belgica antarctica. the journal of experimental biology 209, 399�406. levis n.a., yi s. & lee r.e. 2012. mild desiccation rapidly increases freeze tolerance of the goldenrod gall fly, eurosta solidaginis: evidence for drought-induced rapid coldhardening. the journal of experimental biology 215, 3768� 3773. li a., benoit j.b., lopez-martinez g., elnitsky m.a., lee r.e. & denlinger d.l. 2009. distinct contractile and cytoskeletal protein patterns in the antarctic midge are elicited by desiccation and rehydration. proteomics 9, 2788�2798. lopez-martinez g., benoit j.b., rinehart j.p., elnitsky m.a., lee r.e. & denlinger d.l. 2009. dehydration, rehydration, and overhydration alter patterns of gene expression in the antarctic midge, belgica antarctica. journal of comparative physiology b 179, 481�491. lopez-martinez g., elnitsky m.a., benoit j.b., lee r.e. & denlinger d.l. 2008. high resistance to oxidative damage in the antarctic midge belgica antarctica, and developmentally linked expression of genes encoding superoxide dismutase, catalase and heat shock proteins. insect biochemistry and molecular biology 38, 796�804. michaud m.r., benoit j.b., lopez-martinez g., elnitsky m.a., lee r.e. & denlinger d.l. 2008. metabolomics reveals unique and shared metabolic changes in response to heat shock, freezing, and desiccation in the antarctic midge, belgica antarctica. journal of insect physiology 54, 645�655. parkash r., chahal j., sharma v. & dev k. 2012. adaptive associations between total body color dimorphism and climatic stress related traits in a stenothermal circumtropical drosophila species. insect science 19, 247�262. parkash r., rajpurohit s. & ramniwas s. 2008. changes in body melanisation and desiccation resistance in highland vs. lowland populations of d. melanogaster. journal of insect physiology 54, 1050�1056. m.j. everatt et al. desiccation in polar diptera citation: polar research 2014, 33, 22963, http://dx.doi.org/10.3402/polar.v33.22963 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22963 http://dx.doi.org/10.3402/polar.v33.22963 parkash r., ramniwas s., rajpurohit s. & sharma v. 2008. variations in body melanisation impact desiccation resistance in drosophila immigrans in western himalayas. journal of zoology 276, 219�227. parkash r., sharma v. & kalra b. 2009. impact of body melanisation on desiccation resistance in montane populations of d. melanogaster: analysis of seasonal variation. journal of insect physiology 55, 898�908. pedersen p.g. & holmstrup m. 2003. freeze or dehydrate: only two options for the survival of subzero temperatures in the arctic enchytraeid fridericia ratzeli. journal of comparative physiology b 173, 601�609. popovic z.d., purac j., kojic d., pamer e., worland m.r., blagojevic d.p. & grubor-lajsic g. 2011. lea protein expression during cold-induced dehydration in the arctic collembola megaphorura arctica. archives of biological sciences 63, 681�683. ramløv h. & westh p. 1992. survival of the cryobiotic eutardigrade adorybiotus coronifer during cooling to �1968c: effect of cooling rate, trehalose level and short term acclimation. cryobiology 19, 125�130. ramniwas s., kajla b., dev k. & parkash r. 2013. direct and correlated responses to laboratory selection for body melanisation in drosophila melanogaster: support for the melanisation-desiccation resistance hypothesis. the journal of experimental biology 216, 1244�1254. ring r. & danks h. 1998. the role of trehalose in coldhardiness and desiccation. cryo-letters 19, 275�282. sakurai m., furuki t., akao k., tanaka d., nakahara y., kikawada t., watanabe m. & okuda t. 2008. vitrification is essential for anhydrobiosis in an african chironomid, polypedilum vanderplanki. proceedings of the national academy of sciences of the united states of america 105, 5093�5098. shuker k.p.n. 2001. the hidden powers of animals: uncovering the secrets of nature. london: marshall editions. sinclair b.j., terblanche j.s., scott m.b., blatch g.l., jaco klok c. & chown s.l. 2006. environmental physiology of three species of collembola at cape hallett, north victoria land, antarctica. journal of insect physiology 52, 29�50. slabber s., worland m.r., leinaas h.p. & chown s.l. 2007. acclimation effects on thermal tolerances of springtails from sub-antarctic marion island: indigenous and invasive species. journal of insect physiology 53, 113�125. smith t., wharton d.a. & marshal c.j. 2008. cold tolerance of an antarctic nematode that survives intracellular freezing: comparisons with other nematode species. journal of comparative physiology b 178, 93�100. sømme l. & block w. 1982. cold hardiness of collembola at signy island, maritime antarctic. oikos 38, 168�176. sømme l. & meier t. 1995. cold hardiness of tardigrada from dronning maud land, antarctica. polar biology 15, 221�224. sørensen j.g. & holmstrup m. 2011. cryoprotective dehydration is widespread in arctic springtails. journal of insect physiology 57, 1147�1153. speight m.r., hunter m.d. & watt a.d. 2008. insects and climate. in m.r. speight et al. (eds.): ecology of insects: concepts and applications. 2nd edn. pp. 33�60. hoboken, nj: wiley-blackwell. strathdee a.t. & bale j.s. 1998. life on the edge: insect ecology in arctic environments. annual review of entomology 43, 85�106. teets n.m., peyton j.t., colinet h., renault d., kelley j.l., kawarasaki y., lee r.e. & denlinger d.l. 2012. gene expression changes governing extreme dehydration tolerance in an antarctic insect. proceedings of the national academy of sciences of the united states of america 109, 20744�20749. timmermans m.j.t.n., roelofs d., nota b., ylstra b. & holmstrup m. 2009. sugar sweet springtails: on the transcriptional response of folsomia candida (collembola) to desiccation stress. insect molecular biology 18, 737�746. treonis a.m. & wall d.h. 2005. soil nematodes and desiccation survival in the extreme arid environment of the antarctic dry valleys. integrative and comparative biology 45, 741�750. turner j., bindschadler r., convey p., di prisco g., fahrbach e., gutt j., hodgson d.a., mayewski p.a. & summerhayes c.p. (eds.) 2009. antarctic climate change and the environment. cambridge: scientific committee for antarctic research, 554 pp. watanabe m., kikawada t., minagawa n., yukuhiro f. & okuda t. 2002. mechanism allowing an insect to survive complete dehydration and extreme temperatures. journal of experimental biology 205, 2799�2802. wharton d.a. 2003. the environmental physiology of antarctic terrestrial nematodes: a review. journal of comparative physiology b 173, 621�628. wharton d.a. 2011. anhydrobiosis: the model worm as the model? current biology 21, r578�r579. wharton d.a. & barclay s. 1993. anhydrobiosis in the freeliving antarctic nematode panagrolaimus davidi. fundamental and applied nematology 16, 17�22. worland m.r. 2010. eretmoptera murphyi: pre-adapted to survive a colder climate. physiological entomology 29, 127�137. worland m.r. & block w. 1999. ice-nucleating bacteria from the guts of two sub-antarctic beetles, hydromedion sparsutum and perimylops antarcticus (perimylopidae). cryobiology 38, 60�67. worland m.r., block w. & grubor-lajsic g.o. 2000. survival of heleomyza borealis (diptera, heleomyzidae) larvae down to �608c. physiological entomology 25, 1�5. worland m.r., grubor-lajsic g. & montiel p. 1998. partial desiccation induced by sub-zero temperatures as a component of the survival strategy of the arctic collembolan onychiurus arcticus (tullberg). journal of insect physiology 44, 211�219. worland m.r., leinaas h.p. & chown s.l. 2006. supercooling point frequency distributions in collembola are affected by moulting. functional ecology 20, 323�329. desiccation in polar diptera m.j. everatt et al. 10 (page number not for citation purpose) citation: polar research 2014, 33, 22963, http://dx.doi.org/10.3402/polar.v33.22963 http://www.polarresearch.net/index.php/polar/article/view/22963 http://dx.doi.org/10.3402/polar.v33.22963 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <feff004700650062007200750069006b002000640065007a006500200069006e007300740065006c006c0069006e00670065006e0020006f006d00200064006500200063006f006d007000610074006900620069006c006900740065006900740020006d006500740020005000440046002f0058002d003300200074006500200063006f006e00740072006f006c006500720065006e00200065006e00200061006c006c00650065006e0020005000440046002d0064006f00630075006d0065006e00740065006e002000740065002000700072006f006400750063006500720065006e002000640069006500200063006f006d007000610074006900620065006c0020007a0069006a006e002e0020005000440046002f0058002000690073002000650065006e002000490053004f002d007300740061006e0064006100610072006400200076006f006f00720020006800650074002000750069007400770069007300730065006c0065006e002000760061006e002000670072006100660069007300630068006500200069006e0068006f00750064002e002000520061006100640070006c0065006500670020006400650020006700650062007200750069006b00650072007300680061006e0064006c0065006900640069006e0067002000760061006e0020004100630072006f00620061007400200076006f006f00720020006d00650065007200200069006e0066006f0072006d00610074006900650020006f00760065007200200068006500740020006d0061006b0065006e002000760061006e0020005000440046002d0064006f00630075006d0065006e00740065006e002000640069006500200063006f006d007000610074006900620065006c0020007a0069006a006e0020006d006500740020005000440046002f0058002d0033002e0020004400650020005000440046002d0064006f00630075006d0065006e00740065006e0020006b0075006e006e0065006e00200077006f007200640065006e002000670065006f00700065006e00640020006d006500740020004100630072006f00620061007400200065006e002000520065006100640065007200200034002e003000200065006e00200068006f006700650072002e> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice copepod grazing and its potential impact on the phytoplankton development in the barents sea ulf bamstedt, hans christian eilertsen, kurt s . tande, dag slagstad and hein rune skjoldal bqmstedt, u., eilcrtsen, h. chr.. tande, k. s.. slagstad. d. & skjoldal. h. r. 1992: pp. 339-353 in sakshaug, e . , hopkins. c. c. e. & britsland. n. a. (eds.): proceedings of the pro marc symposium on polar marine ecology. trondheim, 12-16 may 1990. polar research i o ( 2 ) . compiled data from published and unpublished sources on copepod grazing of the large-sized copepods in the barents sea give wide ranges in grazing rates. approximate average values indicate daily rations of 7-18% for copepodite stages v and vi and considerably higher values for the earliest copepodite stages. it is demonstrated that individual variability in gut fullness of copepods from a given locality is typically very high and not closely related to variable food abundance o r depth of occurrence. there is no die1 feeding rhythm during the summer. and even when relating copepod grazing to a number of biotic and abiotic factors through stepwise linear regression analysis, much of the variability remains unexplained. it is suggested that feeding behaviour, food quality and feeding history of the copepods all play important roles as factors which regulate copepod grazing. model simulations on the phytoplankton succession, using literature data on laboratory-determined growth characteristics for solitary cells and colonies of the prymnesiophyte phaeocystis pouchetii and large diatoms, indicate that the extent of the mixed layer and selective grazing by zooplankton are important factors that may explain the occurrence of dense blooms of p. pouchetii colonies, frequently observed during the spring. u. bdmstedt, department of fisheries and marine biology. high-technology centre n-5020 bergen. norway; h.chr. eilertsen and k . s . tande. norwegian college of fisheries. unioersity of tromsm, p . o . box 3083 guleng. n-9001 tromso, norway: d . slagstad, sintefautomatic control, n-7034 trondheim nth, norway; h . r . skjoldal, institute of marine research, p . o . box 1870 nordnes, n-5024 bergen. norway (revised august 1 9 9 1 ) . introduction the barents sea is a very important area econ omically for commercial fisheries; it is therefore of utmost interest t o study the biological pro duction in this area. since the main pelagic fish stocks, capelin (mallotus uillosus) and herring (clupea harengus), feed on zooplankton, there is a direct relation between production-related studies on zooplankton and the commercial fish ery here. the limit for zooplankton production is primarily set by the amount of food consumed, and secondarily by the assimilation efficiency and the metabolic costs associated with life. quantitative information on feeding by zooplank ton may therefore be considered a tool which can be used to estimate zooplankton production, thereby providing important information for an estimation of the carrying capacity for plank tivorous fish stocks. zooplankton is also con sidered a major regulating factor for lower trophic levels. zooplankton grazing may influence the development and succession in the phytoplankton community directly by (1) depressing the total stock and (2) depressing part of the stock by selective grazing. indirectly it may influence the phytoplankton by (3) reducing the grazing press ure from microzooplankton by predation and (4) stimulating algal growth by regenerating plant nutrients. estimates of the total impact of cope pod grazing in the barents sea are restricted to point (1) above. these studies suggest that the impact is small in the spring ( 5 2 0 % of the pri mary production, eilertsen et al. 1989a) but con siderably larger during summer (65-90% of the primary production, eilertsen et al. 1989b; l& 400%, hansen et al. 1990a). in view of the fairly extensive new literature on feeding behaviour and food selectivity in copepods (e.g. huntley 1988; jonsson & tiselius 1990), points (2) and (3) are certainly also important. for example, one of the dominant algal species in the barents sea, the prymnesiophyte phaeocystis pouchetii, may cause a reduction or even inhibition of the feeding in copepods (dagg et al. 1982; schnack et al. 1985, verity & smayda 1989). till now, this effect has not been demonstrated in field studies from the barents sea (eilertsen et al. 1989b) or in labora 340 u. bdmstedt et a1 tabk 1 . calculated individual carbon content (pg) of the copepodite stages of large-sized copepods from thc barents sca. reference sources: (1) protein content from the barents sea in may-june 1987 and conversion factors. bimstedt 1986; (2) slagstad & tande 1990: (3) eilertsen e l al. 1989b. conover & corner 1968: (3) dry weight from the barents sea in august 1988 and conversion factor. bimstedt 1986. stage iv copepodites represent adult females. species/stage c-l c-11 c-ill c-1v c v c-vi ref. calanus finmarchicur 3 8 23 64 193 23 1 ( 1 ) calanus glacialis 4 8 25 100 264 576 ( 2 ) calanus hyperboreus i 16 17 230 743 1399 (3) mefridia longa 193 (4) tory studies using the common copepod species in the barents sea (tande & bimstedt 1987; huntley et al. 1987; hansen et al. 1990b). however, estep et al. (1990) used an incubation technique and image analysis in a field study and found evidences for a variable feeding behaviour of calanus finmarchicus and c . hyperboreus, related to the physiological condition of p . p o u chetii. in this paper we give a brief review of quantitative data on copepod grazing from the barents sea and formulate a simple mathematical model that simulates the effect of copepod grazing on the phytoplankton succession during the first part of the production season. material and methods copepod grazing rates the original papers should be consulted for a description of the material and methods used for the published data. the unpublished data from 1983 were based on in sitl incubations and sub sequent analysis with an elzonem particle coun ter (bimstedt et al. 1985). unpublished results from 1984 and 1987 were produced as described by tande & bimstedt (1985), except that single copepods were analysed in the material from 1984. in 1987, zooplankton was sampled by a slow, vertical haul, using a 1-m diameter wp-2 net with 300 pm mesh and equipped with a non filtering cod-end, 15 i volume. healthy animals were sorted out and kept in 100ml of filtered seawater for up to 30min prior to incubation. -4mbient seawater samples from defined depths with the natural assemblage of particles were prepared in advance by mixing 3.7 x 103bq (100pci) of nah14c03 to 41 water in poly carbonate bottles and incubating them in natural light for 24 hours. the zooplankton samples (100 ml) were mixed with 400 ml radio labelled experimental water, using tissue-culture bottles of 500 ml capacity, and incubated for 0.7-1.0 h at ambient temperature and dim light exposure. incubation was finished by sieving off the cope pods, anesthetising them with ms 222 (ethyl m aminobenzoate), rinsing them individually and putting them into a scintillation vial with 0.5 ml tissue solubiliser. standard procedures were used in the subsequent preparation and scintillation counting of the, samples. grazing rate, in terms of consumed food carbon, was calculated from the ambient concentration of particulate carbon and estimated clearance rate, as given below: pg c intake h-' = pg c ml-' (1) dpmcopepod x ( d p m s t a r t -k d p m s t o p ) m1-l h i n a b a t i o n individual content of body carbon for each species/stage (table 1) was used in the calculation of daily rations (food carbon intake as percentage of body carbon). phytoplankton growth laboratory-derived data on the growth charac teristics of large diatoms and solitary cells and colonies of phaeocystis pouchetii at 0°c (verity et al. 1991 this volume) were used in the model formulation. these parameter values are summa rised below and explained under model formu lation. ~~~ ~ parameter diatoms phaeocysrir phaeocysrrc units solitary cells colonies p 0.33 0.3 0.22 chl a j c 0.04 0.0125 0.01 1 9 0.018 0.037 0.030 ac o.ooo7 0.0005 0.0003 copepod grazing in the barents sea 341 unknown, but they usually begin to form simulmodel formulation a mathematical model has been designed to assess the effect of grazing on the development of the primary production during the spring. the model contains a two-compartment model for phytoplankton and a population of single species of copepods (calanus finmarchicus). the bio logical sub-models are driven by a 1-dimensional (1-d) model of the vertical water column. phytoplankton growth and distribution is described by a 1-d model of a vertical water column where p(t, z) is the concentration of diatoms or phaeocystis pouchetii, w is vertical velocity (usu ally sinking velocity) and k, is the vertical eddy diffusion coefficient. fbiol represents the growth and mortality of the phytoplankton as described by equation 3: (3) where fp(i) is a function that describes the relationship between photosynthetic rate [mg c rng(chla)-' h-i] and light intensity (i), r is the phytoplankton respiration rate and gz is the zooplankton grazing rate. the phytoplankton res piration constant was set at 0.05 d-' (bimstedt & tande 1985; sakshaug & slagstad 1991 this volume). sedimentation loss was assumed significant only for diatoms and a coefficient of 0.02d-' has been applied. assuming no pho toinhibition, the p vs. i relationship is described by: p c = p c 1 e x p -,i ( €21 ~ (4) where ps is maximum carbon-normalised pho tosynthetic rate and & is the carbon-normalised initial slope of the curve (see table above, webb et al. 1974 and sakshaug & slagstad 1991). the model simulates a spring situation, which means that there are no nutrient limitations. during the spring there is a transition from solitary cells to colonies of p. pouchetii, which has a somewhat lower growth rate (see above). however, the colonies seem to be controlled dif ferently, and a mass bloom of colonies is a com mon feature in the late spring. the trigger mechanism for the formation of colonies is taneously with the occurrence of diatoms. results from p-i measurements performed in the field between 1984 and 1989 showed decreased growth rate (based on carbon) of solitary cells of p. pouchetii when the amount of diatoms increased (eilertsen unpubl. data). in the model we have therefore assumed that the production of p. pou chetii colonies is triggered by an increase in the diatom concentration and a switching from soli tary cells t o colonies at a diatom concentration of 1 mg chi a m-3 (25 mg c m-3). surface irradiance was calculated from the theoretical high of the sun at 74"n latitude. an average 50% reduction of insolation due to clouds was assumed, as suggested by data from b j ~ r n ~ y a , provided by the norwegian meteoro logical institute. of this light, 50% was assumed to be usable for photosynthesis. a reflection loss of >lo%, dependent on the solar elevation, was used in the simulations. the attenuatibn coefficient, k, of light in the water column is given below (parsons et al. 1977): k = {k, + 0.0088 chl* + 0.054 (chl*)2/3}/p (5) where k, (m-i) represents the attenuation coef ficient for pure seawater, p is the average cosine of the light field, which has been set at 0.6 (kirk 1983), and chl* is the concentration of light absorbing pigments calculated by the formula of sakshaug & slagstad (1991): chl* = chl a + 1/2 phaeophytin (6) based on data from the barents sea, sakshaug & slagstad (1991) described the relationship between chlorophyll a and phaeophytin as: phaeophytin = 0.45 chl a + 0.02 (7) during the early spring, the copepod biomass is dominated by adult females of c. finmarchicus. in our model we have therefore simplified the copepod population to consist entirely of adult female c. finmarchicus. a detailed model of the grazing impact from this species, based on the energy requirements, has previously been pub lished by slagstad (1981) and slagstad & tande (1990). the ingestion rate is determined by the population size and the clearance rate. the maxi mum clearance rate (fr,) for a copepod is (slag stad & tande 1990): fr, = fro eo (8) where fro is the maximum clearance rate 342 u . bdrnstedt et al. t a b l e 2 . summary of grazing-rate data, expressed as daily ration (carbon intake per day as percentage of copepod carbon content), for the large-sized copepods in the barents sea. analysis techniques: gut-fluor = based on gut content of algal pigments (e.g. mackas & bohrer 1976); “c = radiolabelling technique (e.g. conover & francis 1973); elzone = in situ incubation and electronic particle counting (e.g. b h s t e d t et al. 1985). species stage period daily analysis reference ration technique calanus finmarchicus c. finmarchicus c. finmarchicus c. finmarchicus c. finmarchicus c . finmarchicus c. finmarchicus c. finmarchicus c. finmarchicus c. finmarchicus c. finmarchicus c. finmarchicus calanus glacialis c. glacialis c. glacialis c. glacialis c. glacialis c. glacialis c. glacialis c. glacialis c. glacialis c. glacialis c. glacialis c. glacialis c. glacialis c glacialis c. glacialis c. glacialis c. glacialis c. glacialif c. glacialis calanus hyperboreus c. hyperboreus c. hyperboreus c. hyperboreus c. hvperboreus c. hyperboreus c. hvperboreus c. hyperboreus c. hyperboreus c. hyperboreus c. hyperboreus c. hyperboreus calanus spp. calanus spp. merridia longa m longa c i c-i. i1 c-i1 c-i11 c-111 c-1v c v c v c v ad. female ad. female ad. female c-i c-i1 c-ill c-iv c-iv c-iv c-1v c-iv c-iv c-iv c-iv c v c v c v c v c v ad. female ad. female ad. female c-i c-11 c-111 c-iv c-iv c-iv c-iv c v c v c v ad. female ad. female c-i1 c-111 ad. female ad. female may may may may-june may-june may-june may-june may-june may-june may-june may-june may-june july-aug. july-aug. july-aug. july-aug. may-june may-june may-june may-june may-june july may-june july july may-june may-june may-june may-june may-june may-june july-aug. july-aug. july-aug. july may-june may-june may-june may-june may-june may-june may-june july july may-june may-june july-aug. 0-5.2 4.s148.5 0-1 7 cl1.9 o . m . 6 6.7-82.1 0.3-27.6 o . s l 6 . 8 0-14.9 0-15.4 0.3-55.3 2.8-32.0 75.0 27.9 15.1 58.4 1.9-20.2 1.8-10.6 0.2-10.6 0.1-27.4 1.9-4.5 2.0-21.2 0.1-1 1.5 2 . 6 2 9 . 9 1.7-79 cb24.0 0.8-13.9 0.2-7.7 0-19.2 0.3-8.5 0.5-53.8 67.9 87.5 119.8 102.5 2.2-40 0-7.6 4.8-20.2 0.5-36.0 1.2-2.4 0.2-3.8 0.3-17.4 2 . 6 2 2 . 1 18.2-72.7 1 4 . m 3 . 7 0.2-6.3 cl3 8 gut-fluor i‘c gut-fluor gut-fluor “c 1°c “c gut-fluor gut-fluor gut-fluor gut-fluor gut-fluor gut-fluor gut-fluor gut-fluor gut-fluor i ‘c 1‘c i‘c gut-fluor gut-fluor elzone gut-fluor gut-fluor gut-fluor gut-fluor elzone gut-fluor elzone gut-fluor gut-fluor gut-fluor gut-fluor gut-fluor gut-fluor ijc gut-fluor gut-fluor elzone i ‘c “c gut-fluor gut-fluor gut-fluor “c gut-fluor “c unpublished from 1987 unpublished from 1987 unpublished from 1987 unpublished from 1987 unpublished from 1987 unpublished from 1987 unpublished from 1987 tande & bbmstedt 1985 unpublished from 1987 unpublished from 1987 tande & bimstedt 1985 unpublished from 1987 eilertsen et al. 1989b eilertsen et al. 1989b eilertsen et al. 1989b eilertsen et al. 1989b unpublished from 1987 unpublished from 1987 unpublished from 1987 unpublished from 1987 tande & bimstedt 1985 hansen et al. 1990a unpublished from 1983 hansen et al. 1990a unpublished from 1984 unpublished from 1987 tande & bbmstedt 1985 unpublished from 1983 unpublished from 1987 unpublished from 1983 tande & bimstedt 1985 eilertsen et al. 1989b eilertsen et al. 1989b eilertsen et al. 1989b eilertsen et al. 1989b unpublished from 1984 unpublished from 1984 unpublished from 1987 unpublished from 1987 unpublished from 1983 unpublished from 1984 unpublished from 1984 unpublished from 1987 hansen et al. 1990a hansen et al. 1990a unpublished from 1987 unpublished from 1987 (mi h-l) at a temperature (t) of 0°c. w e used a temperature of 3°c in the model simulations. the parameter value of fro for adult female c. finmarchicus varies from 4 . 2 mi h-’ (huntley 1981) to 12 ml h ‘ (tande & bamstedt 1985). w e have used t h e value 10.0 ml h-i throughout our simulations. an index of electivity (e; ivlev 1961, cited in valiela 1984) was used in some of t h e simulations, in o r d e r t o define a preference towards diatoms, in accordance with current the copepod grazing in the barents sea 343 as given by the i4c-technique (table 2 ) . may reflect a greater technical difficulty with the small est organisms in the analytical procedures. the displayed values given for the early copepodite stages above, especially for c. hyperboreus, might therefore be somewhat biased. nevertheless, con sidering the total information given in table 2 , the daily ration of copepodite stages i-iv appears significantly higher than that of for the older stages. this has subsequently been confirmed for c . finmarchicus from balsfjorden, northern nor way, in laboratory experiments with thalassiosira nordenskioldii and phaeocystis pouchetii as food, two algal species that are commonly predominant in the barents sea (hansen et al. 1990b). the low values on daily rations of metridia longa (table 2) indicate that this species does not graze solely on phytoplankton. data from balsfjorden, northern norway (blmstedt et al. 1985), the west coast of norway (blmstedt & ervik 1984) and the west coast of sweden (biim stedt & tande 1988) all indicate an omnivorous trophic state of this copepod. ory (cf. verity & smayda 1989) e = (ri pi)/(ri + pi) (9) where q is the proportion of species i in the diet and pi, the corresponding proportion in the food environment. the energy requirements for a spawning c. finmarchicus female is taken to be 20pg c d-' (egg production from hirche 1990; gross growth efficiency from peterson 1988). this gives a criti cal food concentration of 83 mg c m-3. results and discussion daily rations of the copepods the compiled data on grazing rate of the large sized copepods (table 2) cover the season from may to august, i.e. most of the production period of the year. the data are expressed as daily rations (carbon intake as percentage of the body-bound carbon) and are given either as ranges or as mean values, dependent on the data available from the different sources. most of the data are for older developmental stages, and these may also be con sidered most reliable. if the median values are used from those studies where ranges are given, and used together with the displayed mean values, a representative average value for each species and stage can be calculated. these values are given below: individual variability in grazing rate in a previous paper by bimstedt (1988) the indi vidual variability of copepod bioenergetics was f x u s e d upon and explained by a suggested vari able nutritional history. the present study gives a comparable example from the barents sea, original data from july 1984 on gut fullness of species/stage c-1 c-11 c-ill c-iv c v c-v1 calanus finmarchicus 40.3 39.5 25.2 44.4 10.0 17.6 calanus glacialis 75.0 27.9 15.1 14.5 16.0 13.7 calanus hyperboreus 67.9 87.5 119.8 35.0 7.4 10.6 2.6 metridia longa excluding metridia fongu, the displayed values indicate that the oldest developmental stages (c v, c-vi) have a typical daily ration of 7-18%, whereas the younger copepodite stages may reach 100% or more. the highest original figures in table 2 were given for calanus hyperboreus, taken from eilertsen et al. (1989b). they used a published single value for the gut evacuation rate of all copepods, and the gut fullness of c-i, c-i1 and c-111 c . hyperboreus was only estimated from similar-sized copepodite stages of c . glacialis. furthermore, the very wide range in daily rations for the early copepodite stages of c. finmarchicus, copepodite stage iv calanus hyperboreus (fig. 1). in the extreme case, shown by copepods from 40 m depth, the individual variability covered a range from 12 to 340 ng pigment individual-', i.e. a factor of 28 in difference between lowest and highest value. by considering these results, together with the curve for in situ fluorescence, it is obvious that food availability alone explains neither the individual variability nor the variation with depth. however, high individual variability may be caused by non-synchronous individual rhythms in feeding, as suggested for c. glacialis by bimstedt (1984), and this may in turn be 344 u . bbmsiedt el d. gut contents (ng chl. equiv. copepod-1) 0 100 200 300 400 0 colmiitr hvptrhoreir.c civ f i g . i . calanur hyperboreus c-iv. july 1984. gut contents of algal pigments (chlorophyll a + phaeophytin), measured on single individuals. as related to depth and relative phyto plankton distribution (shape of in situ fluorescence profile given). governed by the nutritional history of the indi vidual copepod. diurnal variation in feeding published information on possible die1 rhythms in feeding activity of the large-sized arctic copepods suggests the absence of a rhythm during the light season with thq midnight sun (bqmstedt 1984; hansen et al. 1990a; bqmstedt & skjoldal unpubl. data) but a pronounced diurnal cycle in late sum mer, with maximum ingestion during the dark period of the day (head et al. 1985). our results for calanus hyperboreus c-iv and c . glacialis c-v from july 1984 are based on samples consisting of 10 individually analysed copepods (fig. 2). for the first species, highest gut contents were recorded in the afternoon, but the temporal vari ation was relatively small in relation t o the indi vidual variability at each depth and between depths. c. glacialis showed pronounced vertical fluorescence (v) 0 4 8 1 2 0 4 8 1 2 0 4 8 1 2 0 4 8 1 2 0 4 8 1 2 nl7-l-n m ml7-n-l rl7-n-n gut contents (ng chl.equiv. cop.’) 0 100 200 300 0 16.30 40 0 100 200 300 23.50 0 100 200 300 06.40 0 100 200 300 12.40 10.30 f 0 100 200 300 v 18.50 c. hyperboreus m 16.50 c. glacialis fig. 2 . calanur hyperborem c-iv and c. glacialis c-v. vertical profiles of grazing rate (mean and se. + or -)of copepods sampled 5 times during a 24-hour period in july 1984. each point represents i0 individually analysed copepods. the displayed curve represents relative in situ fluorescence (in volts). copepod grazing in the barents sea 345 fig. 3. calanus finmarchicus and c. glacialis. copepod grazing rate versus depth of occurrence. the data from may-june 1987 represent vertical profiles from up to 8 different localities, and the wide ranges have necessitated the use of a logarithmic scale. 0 a0 ad. female u . . . . . . . . . . . . . . . . . . . . o m o m 0 0 > 0 0 0 w o 0 0 0 0 0 0 0 rn 00 03 0 0 0 0 <d 0 0 0 0 00 0 ooco o m 0 o o a m q o o 0 0 0 s i m e v con. --. . m.. . . . .. . . variation in gut fullness, together with high indi vidual variability. the data therefore support the suggestion that there is no die1 rhythm in copepod grazing rate during the summer in the barents sea. grazing in relation t o depth reduced copepod gut contents with depth of occurrence has previously been reported from i 10 100 0 ood . o o q o 0 0 00 0 0 o a00 0 0 oq o o a od cm om om 0 0 o m a t.. . . . . . . . . . . . . . . . . . . . . . . ood d o q o 0 0 00 0 0 o 0000 0 0 00 o o a 00 om, o m c w 0 0 a o m a co w o 0 ) o 0 0 0 stnee v cnn, the barents sea for calanus finmarchicus and c . glacialis (bimstedt 1984; tande & bimstedt 1985). new grazing-rate data for these two species, collected during a cruise in may-june 1987 (bimstedt & skjoldal unpubl. data) have been plotted versus the depth of sampling (fig. 3). the data represent results from 8 different stations, classified either as mid-bloom or post bloom situations. a logarithmic scale has been used in order to get as high a resolution as possible 346 u. bdmstedt et al. of the data. the scatter in the data is very high, irrespective of species or developmental stage, and there is obviously no simple relationship between weight-specific grazing rate and depth of occurrence. this will be further discussed in the section below. crazing rate in relation to environmental factors several investigators have tried to find a simple and close relationship between the amount of available food and the feeding rate of copepods, as is typically found in laboratory experiments (e.g. frost 1972; k i ~ r b o e et al. 1982; hansen et al. 1990b). these attempts have generally failed, both when food has been expressed in terms of particulate protein or carbohydrate (bhmstedt 1984) and when expressed as chlorophyll a (boyd et al. 1980; dagg & grill 1980; dagg & wyman 1983; head et al. 1985, 1988; tande & bhmstedt 1985; hansen et al. 1990a). however, huntley (1981), using shipboard incubations, found highly significant relationships (r2 varying from 0.949 to 0.961) between the concentration of natural phytoplankton and grazing rate of the three arctic calanur species. in laboratory experiments where the functional relationship of grazing rate to food concentration is recorded, copepods are exposed to different concentrations of homogeneous food, everything else being constant. such a simple situation is probably not found in the natural habitat and huntley (1988) lists 7 forcing functions for the net response of calanus to its current environment. five of these functions (light, body weight, tem perature, food concentration and food size) can easily be quantified, whereas two of them (food quality and feeding history) are more difficult to handle quantitatively. possible effects on calanus of the two latter factors have been reviewed by huntley (1988), and we will return to food quality in a later section and concentrate on purely quan titative environmental factors here. data on environmental parameters and cope pod grazing from a cruise in the barents sea in may-june 1987 (bimstedt & skjoldal unpubl. data) have been taken both from stations where the spring phytoplankton bloom was intense (mid bloom situation) and from stations where the bloom had terminated ( post-bloom situation). the mid-bloom stations had a constant salinity with depth, ranging from 35.00 to 35.10%0 and temperature usually between 1.3 and 2.2"c, indi cating atlantic water. a strong nutricline at 40 nutrient concentration (m mol m-3) sutrient concentration (rn mol m-3) 0 5 0 100 pigment concentration (mg m 3 ) 2 3 6 8 -t chl posbloom phxo ponbloam i fig. 4. may-june 1987. vcrtical profiles of nutrients (nitrate and silicate). chlorophyll a and phaeopigmcnts at stns. 923 (mid hloom station) and 961 (post-hloom station). data from bimstcdt & skjoldal (unpuhl.). 0 2 0 4 0 depth (m) 6 0 8 0 1 0 0 abundance (ind. m-3) abundance (ind. m-3) copepod grazing in the barents sea 347 0 60 20 40 0 0 midbloom t o 4 0 6 0 8 0 loo 0 0 1 fig. 5. may-june 1987. vertical distribution of total zooplankton biomass (collected by a 200pm mesh net) and abundance of adult females and stage v copepodites of ca/anusfinmarchicus and c. glacialis at stns. 923 (mid-bloom station) and 961 (post bloom station). data from bhmstedt & skjoldal (unpubl.) to 60m depth, with reduced concentrations of nitrate, phosphate and silicate above this, and with high chlorophyll a concentrations down to at least 60m depth, including a pronounced sub surface maximum, were common features for these stations. fig. 4 gives one example by show ing the vertical profiles at station 923, which was a typical mid-bloom station. the post-bloom stations were all influenced by arctic water of low salinity and temperature in the surface, the salinity distribution defining a strong pycnocline at about 30m depth. typically, nutrients were completely depleted above the pycnocline, and the nutricline therefore corresponded well with the pycnocline. the chlorophyll a concentration was low in the nutrient-poor surface waters, while there was a maximum at 25 to 50 m depth. station 961 is given as an example in fig. 4. the zooplankton biomass and abundance of copepods, as exemplified by adult females and copepodite stage v calanus finmarchicus and c. glacialis, differed between mid-bloom and post bloom stations. biomass and abundance were both fairly constant at depths down to 100 m in the mid-bloom stations, except for the reduced values in the surface water (fig. 5 , from station 923). biomass and abundance were commonly higher in the post-bloom stations, with a pro nounced subsurface maximum at depths from 20 to 60m (fig. 5 , from station 961). the grazing rate of copepods, here exemplified by adult females and stage v copepodites of c . finmarchicus and c . glacialis from two stations, showed great variability at all sampling depths (fig. 6, from stns. 923 and 961, respectively). however, the grazing rate was considerably higher in the mid-bloom situation, with maximum values close to 160 ng pigment mg-' protein h-', than in the post-bloom situation, where the graz ing rate did not exceed 25 ng pigment mg-' pro tein h-l. reduced grazing rate was also recorded in the surface water, and there was a pronounced subsurface maximum especialiy in the post-bloom situation, situated at 40-50 m depth, closely below the chlorophyll maximum. the above grazing-rate data have been evalu ated against biotic and abiotic environmental con ditions through linear stepwise regression analyses, separating stations defined as mid bloom situation and post-bloom situation, 348 u. bdmstedt et al. g r a z i n g r a t e ( n g c i i i a equiv. (1118 l)rotein)-1 11-1) 0 a 2o 40 6 0 80 i w e 120 e (1 x 5 6 *" 40 60 80 in i2( o 40 ao 120 m o 0 0 0 0 0 o m o m c o o 0 o m . . . . . . . ~ c m a l c . midbloom . . . . . . 0 0 0 o < 0 0 40 80 120 0 0 0 c v . midbloom 0 0 0 0 0 0 0 0 0 10 20 3 female, postbloom 7 c v . postbloom i-- 1", 0 fig. 6 . colanus finmarchicm (a) and c . glacialis (b), may-june 1987. vertical profiles of weight-specific grazing rate of copepodite stage v and adult females. the mid bloom situation is represented by stn. 923 and the postbloom situation by stn. 961. data from bimstedt & skjoldal (unpubl.). table3. calanusfinmarchicus and c . glacialis. results of stepwise regression analysis on grazing rate (ng chl a equiv. mg-' protein h ' ) versus four independent variables (depth in m. chlorophyll a concentration in rng rn-'. primary production in rng c rn-' d ' . and water density in sigma-1) of stage v copepodites and adult females. the f-values from the statistical analysis are given, and those variables with f-values exceeding 4.0 (marked by an asterisk) have been included in the regression equations, which resulted in the displayed determination coefficient ( r 2 ) . period/stage depth chl. a prim. prod. density r2 cahnm finmarchicus midbloom stage v copepodites adult females postbloom stage v copepodites adult females calanus glaciab midbloom stage v copepodites adult females postbloom stage v copepodites adult females 7.03' 41.89. 2.44 0.28 2.77 0.08 2.90 1.37 15.39' 5.41' 58.96' 14.81. 0.18 0.37 0.44 1.21 0.91 18.30' 0.48 0.47 0.01 0.72 0.49 0.96 29.91' 12.93' 12.86' 22.54' 106.97' 11.39' 3.80 3.29 ~~ 0.743 0.823 0.826 0.296 0.764 0.655 copepod grazing in the barents sea 349 suggested inhibitory effect on copepod grazing by this species (e.g. dagg et al. 1982; schnack et al. 1985; claustre et al. 1990) may have severe consequences upon the development of the phy toplankton community. however, recent studies on copepod grazing, where the dominant calanus species from the barents sea have been used, do indicate active grazing upon p . poucherii (tande & bpmstedt 1987; huntley et al. 1987; eilertsen et al. 1989b). an explanation for this conflict between investigators was given by estep et al. (1990) who suggested that the physiological con dition of the algal colonies determines the pal atability for grazers. their results indicated inhibitory effects upon grazing when the colonies were healthy, but very high grazing rates on sus ceptible colonies. such a change with age of algal cells has also been reported for the bloom-forming haptophycean flagellate chrysochromulina poly lepis (nielsen et al. 1990). respectively, in two sets of data (table 3). we selected two biotic variables reflecting the food environment (chlorophyll a concentration and primary production) and two abiotic variables (depth and sigma-t of the water) that are com monly found to be important for the behaviour of the copepods. the chlorophyll a concentration and density distribution contributed significantly (f > 4.0) in explaining the grazing rate of c. finmarchiclrs in mid-bloom and post-bloom situations. depth contributed significantly in two cases and primary production in a single case for c . finmarchicus (table 3 ) . for c . glacialis density was the only independent variable that showed a significant contribution, and in the post-bloom situation none of the four variables showed an f-value exceeding 4.0. the results show that the relationship between the environmental condition and copepod feeding intensity is not usually a simple one. the visual impression from the graphs indicates that maxi mum grazing rate tends t o occur somewhat below the chlorophyll maximum, and data transform ation might therefore have improved the cor relations. however, our main purpose was to evaluate if a simple relationship existed in the natural habitat, with a direct coupling between environmental factors and the grazing rate. our data indicate that the chlorophyll distribution and water density usually govern the grazing rate of copepods, although much of the variability in grazing rate is not explained by these two factors. grazing selectivity a selective grazing behaviour of zooplankton may force the phytoplankton species succession and therefore may be considered a major structuring ecological factor. from the early considerations where cell size and concentration of microalgae were the main regulating factors (e.g. frost 1972) feeding behaviour and importance of food quality have been major components in the explanation of grazing control (see e.g. huntley 1988 and references therein). more recently, attention has also been put to toxicity and unpalatability of algae in scandinavian and arctic waters (huntley et al. 1987; tande & bimstedt 1987; nielsen et al. 1990; estep et al. 1990). in the barents sea, where phaeocystis pouchetii usually constitutes a major part of the phytoplankton community (eilertsen et al. 1989a and unpubl. results), a simulation results during the spring the mixed layer may vary from 20m near the ice border t o more than 100m in the atlantic water. fig. 7a shows that the population succession of diatoms and phaeocystis pouchetii when no grazing occurs, is influenced when using alternatively 25 m, 40 m and 75 m as mixed depth. diatoms will gradually dominate in the first two cases, whereas p . pouchetii is better adapted than diatoms to the situation with 75 m mixed depth. figure 7b shows that the relative initial concentration is of great significance for the balance between the two algal forms. with two times higher initial concentration of diatoms (po = 0.5 x do) p . pouchetii stabilises at a low level, whereas diatoms increase exponentially. with higher initial concentrations of p. pouchetii (po = 2 x d o resp. 4 x do), a dominance of p . ' pouchetii colonies will be established (fig. 7b). the distribution of the grazing pressure from 2,000 adult females calanus finmarchicus has a significant influence on the algal community suc cession (fig. 7c). with only a slight preference towards diatoms ( e = 0.2) total algal biomass will be low and slightly dominated b y diatoms. a stronger preference towards diatoms ( e = 0.4 and 0.9, respectively) generates a correspondingly higher dominance of p . pouchetii. in the case with very strong preference towards diatoms ( e = 0.9), the critical diatom concentration for trig gering production of p. pouchetii colonies is not 350 u . bdmstedt et a1 '? e 0 f p? e 0 e" 150 100 50 1 l o 20 '1 l o 20 '1 march april reached and production of p . pouchetii solitary cells is exponential (fig. 7c). however, solitary cells of p . pouchetii a r e usually not found in concentrations higher than 0 . 5 m g chl a m 3 (40 mg c m 3 , eilertsen unpubl. results). micro zooplankton grazing may account for this dis crepancy. thus, t. dale (pers. comm.) found that the ciliates rapidly increased their biomass during the spring bloom in the barents sea, and eilertsen (unpubl. results) found a high phaeopigment/chl a ratio (ranging from 0.3 t o 2 . 3 ) during times with dominance of p . pouchetii solitary cells. d u e to lack of quantitative data o n this problem, we have not included it in our model. none of the above simulations indicate any fast succession in spring towards an extensive 10 20 1 may fig. 7. simulated population succession (mg c m-') in a community with diatoms (broken lines) and phaeocystis pouchetii (solid lines) with defined p and ac (see text). a . no grazing hut variahle extent of the mixed layer (75, 40 and 25 m). b . no grazing but variahle initial ratio between biomass of p . pouchetii and diatoms (p,,/d,) = 0.5; 2.0; 4 . 0 ) . c. grazing by 2000 adult female calanus finmarchicus with variable preference towards diatoms ( e = -0.2: 0.4: 0.9). dominance of p . pouchetii colonies in high con centrations. preliminary studies in the laboratory (eilertsen unpubl. results) indicate that t h e growth characteristics of p . pouchetii may be more competitive than shown by verity e t al. (1991 this volume). w e have therefore simulated the succession with three alternative values for p and & for the colonial form of p . pouchetii (fig. 8a and 8 ) where the lowest values represent those given by verity e t al. (1991). t h e simulation assumes a slight grazing selectivity towards dia toms (e = 0.2) from 2000 copepods. t h e simu lation results show that, under the conditions given, p . pouchetii can hardly maintain a high dominance over diatoms with the established growth parameters. an increase in p or & changes this situation considerably. and with a copepod grazing in the barents sea 351 a 100 3 75 e 0 e" 50 fig 8 simulated population succession (mg c mg-') in a community with diatoms (broken lines) and phaeocystrs pouchetii (solid lines), mixed depth = 40 m and grazing by 2000 adult females calanus 25 -_.__ l o o 8 0 75 finmarchicus with e = 0 2 (slight preference towards 0 diatoms) a variable f w e growth parameter p (0 22, 0 33, 0 46) for the colonial forms of p pouchetri. b variable growth parameter d (0 0 0 0 3 . 0 ooo6, 0 oaos) for the colonial forms of p pouchetii march april 25 combined increase of both parameters the poten tial for a rapid development of a heavy bloom of p . pouchetii colonies is given. the simulation results indicate that vertical stratification and grazing by zooplankton are vari ables of great significance for the numerical bal ance between diatoms and p. pouchetii. the occurrence of two different modes of p. pouchetii and lack of knowledge about the mechanisms involved in the production of these forms com plicate the picture. the small solitary flagellates have a size of 3-8 pm (tande & bqmstedt 1987) which indicate low retention efficiency for cope pods (cf. berggren et al. 1988). microzooplankton can graze upon these with high efficiency (johnsson 1986), whereas the macrozooplankton grazing on phaeocysris colonies still is con troversial (see above). therefore, identification of the main micrograzers and quantitative measurements of microzooplankton grazing on microflagellates is an area which should render high priority in future ecological investigations in the barents sea. furthermore, the importance of specific properties of p. pouchetii also needs much more attention. this includes a positive buoyancy of especially large colonies of p. pouchetii (skres let 1988), inhibitory effects on its own growth in dense populations (kayser 1970) and release of dissolved organic matter (batje & michaelis 1986) that may affect growth of microalgae. none of these aspects have been included in our model formulation. acknowledgements. we thank all the colleagues that have contributed in the field work and laboratory work during the cruises, experiments and analyses from which the results in this paper were produced. we thank p. verity for constructive critique. we also thank the organisers of the research program, the norwegian fisheries research council and the ministry of the environment for the very stimulating period with pro mare. references bamstedt, u . 1984: die1 variation in the nutritional physiology of calanusglacialis from lat. 18"n in the summer. mar. biol. bamstedt, u . 1986: chemical composition and energy content. pp. 1-58 in corner e. d. s. & o'hara s. c. m . (eds.): the biological chemistry of marine copepods. oxford university press, new york. bamstedt. u. 1988: ecological significance of individual varia bility in copepod bioenergetics. hydrobiologia 1671168. 43 59. bamstedt. u . & ervik, a . 1984: local variation in size and activity among calanus finmarchicus and metridia longa (copepoda. calanoida) overwintering on the west coast of norway. j. plankton res. 6 , 843-857. bamstedt, u . & tande, k . s. 1985: respiration and excretion rates of calanus glacialis in arctic waters of the barents sea. mar. biol. 87, 259-266. 79, 251-261. 352 u . bimstedt et al. bimstedt, u & tande. k . s 1y88: physiological responses of calanus finmarchicus and merridia longa (copcpoda: cal anoida) during the wintcr-spring transition. mar. biol. y9. bimstedt, u.. tande. k . s & nicolajscn. h 1985: ecological investigations on the zooplankton community of balsfjorden. northern norway: physiological adaptations in merridta longa (copepoda) to the overwintering period. pp. 313-327 in gray. j . s . & christiansen. m. e. (eds.): marine biology of polar regions and effects of stress on marine organums. j wiley and sons. batje. m. & mtchaelis. h. 1986: phaeocvsris poucherii blooms in the east frisian coastal waters (german bight. north sea). mar. biol. 93. 21-27. berggren. u . . hansen. b . . ki0rboe.t. 1988. food-size spectra. ingestion and growth of the copepod acarria fonsa: impli cations for the determination of copepod production mar. biol. 99. 341-352. boyd. c. m.. smith, s . l. & cowles. t . j . 1980: grazing patterns of copepods in the upwelling system of peru. limnol. oceanogr. 24. 583-596. claustre. h.. poulet. s . a , . williams. r . . marty. j . c . coombs. s.. ben. mlih. f.. hapette, a . m. & martin jezequel. m. 1990: a biochemical investigation of a phaeo cvsris sp. bloom in the irish sea. 1. mar. biol. ass. uk 70. 197-207. conover, r. j . & corner. e . d. s . 1%8: respiration and nitrogen excretion by some marine zooplankton in relation to their life cycles. 1. mar. biol. ass. uk 48. 4!+75. conover, r. j . & francis, v. 1973: the use of radioactive isotopes to measure the transfer of materials in aquatic food chains. mar. biol. 18. 272-283. dagg, m. j . & grill, d. w. 1980: natural feeding rates of cenfropages rypicur females in the new york bight. limnol. oceanogr. 25. 597-609. dagg. m. j . , vidal. j.. whitledge, t. e . . lverson. r . l. & goering, j . j . 1982: the feeding, respiration and excretion of zooplankton the berings sea during a spring bloom. deep sea res. 29. 45-63. dagg, m. j. & wyman. k. d. 1983: natural ingestion rates of the copepods neocalanur plumchrus and n . crisfarus cal culated from gut contents. mar. ecol. prog. ser. 13. 37-46. eilertsen. h. chr., tande. k. s. & hegseth. e. n. 1989a: potential of herbivorous copepods for regulating the spring phytoplankton bloom in the barents sea. rapp. p . o . reun. cons. lnt. explor. mer 188. 156163. eilertsen. h . chr., tande, k. s . & taasen. j. p. 1989b: vertical distribution of primary production and grazing by calanus glacialis jasehnov and c. hyperboreur krayer in arctic waters (barents sea). polar biol. 9. 25%260. estep, k. w.. nejstgaard. j . chr., skjoldal, h . r. & rey. f. 1990: predation by copepods upon natural populations of phaeocysris poucherii as a function of the physiological state of the prey. mar. ecol. prog. ser. 6 7 . 23s249. frost. b. w . 1972: effect of size and concentration of food particles on the feeding behaviour of the marine planktonic copepod calanus pacilfcus. limnol. oceanogr. 17. 8 0 5 8 1 5 . hansen. 8.. berggreen. u . c . . tande. k. s . & eilertsen. h. chr. 1990a: post-bloom grazing by calanus glacialis, c. finmarchicus and c. hyperboreus in the region of the polar front. barents sea. mar. biol. 104, 5-14. hansen. b.. tande. k. s . & berggreen. u. c . 1990b: on the trophic fate of phaeocystis poucherii (hariot), i l l . functional 31-38. anus finmarchicus (copepoda) fed diatoms and phaeocvsris. j. plankton res. 12. 1173-1187. head. e . j . h . . bedo. a . & harris. l. r . 1988: grazing, defecation and excretion rates of copepods from inter-island channels of the canadian arctic archipelago. mar. b i d . 99, 333-340. head. e . j . h.. harris. l. r . & abou debs, c . 1985: effect of daylength and food concentration on in situ diurnal feeding rhythms in arctic copepods. mar. ecol. prog. s e r . 24, 281 288. hirche. h.-j. 1990: egg production of calanusfinmarchicus at low temperature. mar. b i d . 106. 53-58. huntley. m . 1981: nonselective. nonsaturated feeding by three calanid copepod species in the labrador sea. limnol. oce anogr. 26, 831-842. huntley, m. 1988: feeding biology of calanus: a new perspec tive. hydrobiologia 167/168. 83-99. huntley. m.. tande. k. & eilertsen. h . chr. 1987: on the trophic fate of phaeocysris poucherii (hariot). 11. grazing rates of calanus hyperboreus ( k r ~ y e r ) on diatoms and dif ferent size categories of phaeocysris poucherir. j . exp. mar. biol. ecol. 110. 197-212. jonsson, p. r . 1986. particle size selection, feeding rates and growth dynamics of marine planktonic oligotrichous ciliates (ciliophora: oligotrichina). mar. ecol. prog. ser. 33, 265 277. jonsson. p. & tiselius, p. 1990: feeding behaviour, prey detec tion and capture efficiency of the copepod acarria ronsa feeding on planktonic ciliates. mar. ecol. prog. ser. 60. 35 44. kayser. h. 1970: experimental-ecological investigation on phaeocysris poucherii (haptophyceae): cultivation and waste water test. helgolander wiss. meeresunrers. 20, 195-212. k10rboe. t.. mbhlenberg. f. & nicolajsen, h . 1982: ingestion rate and gut clearance in the planktonic copepod cenrropages hamarus (lilljeborg) in relation to food concentration and temperature. ophelia 21, 181-194. kirk. j. t. 0. 1983: lighf and phorosynrhesis in aquatic eco s y s t e m . cambridge university press, melbourne. mackas. d. & bohrer, r. 1976: fluorescence analysis of zooplankton gut contents and an investigation of die1 feeding patterns. j. exp. mar. biol. ecol. 25. 77-85. nielsen, t. g . . kiarboe, t. & bjarnsen. p. k. 1990: effects of a chrysochromulina polylepis subsurface bloom on the planktonic community. mar. ecol. prog. ser. 62, 21-35. parsons. t . r., takahasi, m. & hargrave. b. 1977: biological oceanographical processes. pergamon press, oxford. 332 pp. peterson. w. t. 1988: rates of egg production by the copepod calanus marshallae in the laboratory and in the sea off oregon, usa. mar. ecol. prog. ser. 17. 229-237. sakshaug. e. & slagstad. d. 1991: light and productivity in polar marine ecosystems: a physiological view. pp. 6%85 in sakshaug. e.. hopkins. c. c . e. & oritsland. n. a . (eds.): proceedings of the pro mare symposium on polar marine ecology. trondheim. 12-16 may 1990. polar research i o ( 1 ) schnack, s . b.. smetacec, v., von bodungen. b. & stegmann. p. 1985: utilization of phytoplankton by copepods in ant arctic waters during spring. pp. 65-81 in gray, j. s. & christiansen. m. e. (eds.): marine biology of polar regions and effecrs of stress on marine organisms. j . wiley and sons. skreslet. s . 1988: buoyancy in phaeocysris pouchetit (hariot) lagerheim. j . exp. mar biol. ecol. 119, 157-166 responses in grazing demonstrated on juvenile stages of c a b slagstad. d . 1981: modeling and simulation of physiology and copepod grazing in the bnrents sea 3 5 3 population dynamics of copepods. modeling, fdentificafion and c o n f r o l 2 , 119-162. slagstad, d. & tande. k . s. 1990: growth and production dynamics of calanus glacialis in an arctic pelagic food web. mar. ecol. prog. ser. 63? 189-199. tande. k. s . & blmstedt, u . 1985: grazing rates of the cope pods calanus glacialis and c . finmarchicus in arctic waters of the barents sea. mar. b i d . 87, 251-258. tande. k . s . & bbmstedt. u . 1987: on the trophic fate of phaeocysfis pouchefii. 1. copepod feeding rates on solitary cells and colonies of p. poucherii. sarsia 72. 312-320. valiela. i . 1984. marine ecological processes. springer verlag. new york. 546 pp. verity. p. & smayda. t. j . 1989: nutritional value o f phaeocystis pouchetii (prymnesiophyceae) and other phy toplankton for acarfia spp. (copepoda): ingestion, egg pro duction, and growth of nauplii. mar. biol. 100. 161-171. verity, p. g . . smayda, t. j . , sakshaug. e. 1991. photo synthesis. excretion, and growth rates of phaeocysfis colonies and solitary cells. pp. 117-128 in sakshaug. e.. hopkins. c. c. e. & britsland. n . a. (eds.): proceedings of the pro mare symposium on polar marine ecology. trondheim. 12-16 may 1990. polar research l o ( 1 ) . webb, w. l.. newton, m., starr, d. 1974. carbon dioxide exchange of a l n m rubra: a mathematical model. oecologia 17. 281-291. research note organochlorine and mercury concentrations in eggs of grey plovers (pluviulis squuturola) breeding in the lena delta, seven eggs from four clutches of grey plovers ( p i ~ w i a l i s syuararola) breeding in the lena delta, sakha republic, yakutia, in 1997 were analysed for persistent organochlorines and mercury. contamination levels were low and within the same range as found i n eggs from waders (charadriiformes) breeding i n north-west europe. one exception was chch, averaging 99.2 ng g -' fresh egg mass, a level about ten times higher than in wader eggs from north-west europe. p-hch accounted for 98% of the total hch concentration. there are indications that the pesticide levels may reflect former local use. cpcb level (57.0 ng g-', 62 congeners) and mercury concentration (68.7 ng g') can be considered low. k. -m. ero, p. h . becker & u. somtner, hutituta of aviciii research (itistitut fur vogelforsckung). vogelwrrrta h e l g o l m r l , an c k r vogelwurte 21, 0-26386 willzeltmhciven, gertnutiy generally known to be sensitive bioindicators of toxic and persistent environmental chemicals, birds are researched in several countries to monitor the current condition of the environment as well as to identify long-term trends (e.g. becker, heid mann et al. 1992; newton & wyllie 1992; furness 1993; bignert et al. 1995: becker, thyen et al. 1998). in particular, bird eggs have many advnn tages with respect to sampling for toxic contani ination (gilbertson et al. 1987; becker 1989). eggs reflect geographical and annual contamination levels of the breeding sites, even if the species migrate over large distances (becker 1989: dietrich et al. 1997: becker, thyen et al. 1998). during the last decades i t has become evident that arctic regions. even if only sparsely populated and far from industrial activities, are contaminated with various toxic chemicals and heavy metals. mainly by airborne long-range transport from industrialized regions (e.g. rees & kapitsa 1994: muir et al. 1995; savinova et al. 1995; amap 1998). ddt, pcb, hcb and hch are the chemicals most regularly measured in the euro pean arctic (steinness 1997). but despite the fact that pollution of different arctic regions has been repeatedly documented and that arctic ecosystems are especially vulnerable to pollution, contamina tion of biota by environmental chemicals has been little studied (see compilation i n amap 1998). this seems to hold i n particular for the russian arctic, even though the entire flyway populations of several wader species breed there. during an expedition to the lena delta, one of the largest and most important breeding areas in the russian arctic (laboutin et al. 1985; pozdnyakov et al. 1996: gilg et al. 2000), we collected grey plover (pluvialis squnrurola) eggs to investigate contam ination by environmental chemicals. study area and methods the lena delta is situated in northernmost east siberia (sakha republic. yakutia). at the border between the laptev sea in the north and the kharaulakh ridge i n the south (fig. 1). grey plover exo et al. 2000: polrir rrsrnrch 1 9 ( 2 ) , 261-265 26 i f i g . i . location of the study area, the lena delta in the eurasian arctic. eggs were collected in the south-eastem delta, near the lena nordenskiold international biological station (72“n, 128”e; see prokosch 1995, 1997; solomonov 1995). in the south-eastem part of the delta grey plover breeding density was about 1 pairkm’ in 1997 (for details see exo & stepanova 3000). seven eggs from four clutches were collected in juneijuly 1997: four eggs of one abandoned clutch, and three unhatched eggs from three different nests. all eggs were frozen at -18‘c prior to further treatment. eggs were extracted and analysed as in previous studies (for details, see sommer et al. 1997; becker, thyen et al. 1998). for determination of organochlorine compounds. 2 g of the egg homogenate were dried with sodium sulphate, cleaned by a column filled with silica gel, eluted with n-hexane : dichloromethane (8 : 2), evaporated and taken up in 250 kt1 toluene. a gas chromatograph hp 5890, series 11, coupled with a mass selective detector h p 5971 was used, with electron impact ionization and measure in sim mode. a ht-5-column made by sge with a length of 25 m was utilized for separation. for mercury determination, 100 mg egg homogenate were prepared with a mixture of nitric acid, chloric acid and perchloric acid in a partly closed test tube, in accordance with kruse (1979). an atomic absorp tion spectrometer (fims-400, perkin elmer) with an integrated flow injection module of the fias series was used for the measurements. the organochlorine compounds analysed were hexachlorobenzene (hcb), three isomers of hexa chlorocyclohexane (a-, pand y-hch, also given as chch), the ddt (dichloro-diphenyl-trichloro ethane) group (expressed as cddt including six metabolites: o,p‘-ddt, o,p’-dde [o,p’dichloro diphenyl-dichloroethene], o,p’-ddd [o.p’-di chloro-diphenyl-dichloroethane], p,p’-ddt, p,p’ dde, p,p’-ddd), and polychlorinated biphenyls (pcbs). we analysed 6 2 congeners of pcbs (expressed as cpcb; see table 1); 41 of them were recorded individually. concentrations are given as ng g-‘ fresh (wet) egg mass. detection limits were 0.1 n g g g ’ fresh egg mass for mercury, and 0.3-0.9 ng g-’ for all examined organochlorines. the values presented are arithmetic means 21 sd of the four clutches (the data of the multi-egg clutch were averaged before). to allow direct comparisons with the literature, concentrations expressed on a dry mass or lipid mass basis were converted to fresh mass basis assuming dry mass = 0.26 x wet mass, and lipid mass = 0.09 x wet mass, respectively, in accordance with mattig et al. (1996). results shell thickness varied between 0.19 and 0.24 mm (0.22 f 0.02 mm), and the shell thicknesf index calculated according to ratcliffe ( 1967) between 0.73 and 1.04 (0.93 f 0.14). the organochlorine pesticides dominated among the contaminants (table 1). /i-hch (97.6 ng g-l) the most stable compound of all hch isomers (koch 1991) -accounted for 98% of chch. p,p’-dde accounted for about 91% of cddt; p,p’-ddt/p,p’-dde ratio was 0.063. o,p’ dde, o,p’-ddd and o,p’-ddt were not detected in any of the samples. in contrast to the pesticides, industrial chemi cals like pcb, hcb and mercury were found in comparatively low concentrations (table 1). about 45% of the cpcb ( 5 7 . 0 n g g ’ ) was contributed by the eight indicator pcb congeners. hcb (20.2) and mercury levels (68.7) were also low. discussion keeping in mind that we analysed only eggs from four clutches of one species and that pollutant studies of waders breeding in the russian arctic 262 organochlorine and mercury concentrations in eggs of grey plovers 7 ' ~ i b / ~ /. contaminant concentrations i n four grey plover clutches from the lena delta, yakutia in 1997. concentrations are expressed i n tig g ~' fresh egg mash. yhch = sum of three isomers cl-, /jand y-hch; zddt = suni of six metebolite\ 0.p'-ddt. p.p'-ddt. o.p'-ddd, p,p'-ddd. o,p'-dde. p . p dde; cpcb = sum of 62 pcb congeners; addirionally the \uni of eight pcb indicator congeners ( * ) and the pcb c o n g c n w accounting fcir more than 57r to cpcb are given: pcb congeners referred to by iupac-nurnhers (ballschmiter & zsll 1980). varkahlr mean rd min. max chch 99.2 r-hch 1 . 1 i(-hch 97.6 p h c h 0.2 hcb 20.2 cddt 226. i p.p'-ddt 16.6 cpcb 57.0 pcb 28* 5.2 pcb 52* 1.6 pcb 95 -1.6 pcb 101:'' 3.1 pcb 110 3.3 pcb 118" 3.3 pcb 132 2.9 pcb 138* 3.4 pcb 149 3.9 pcb 153* 5.8 pcb 175 3.3 pcb 180* 3.5 pcb 190* 0 "8 pcbs 25.8 hg 68.7 p.p'-dde 205.0 80.3 17.7 0.7 0.6 79.7 17.1 0.5 0.0 17.j 8.0 172.1 99.5 22.5 4.1 114.5 95.4 15.0 39.6 0.3 4.8 0.4 i . 2 1 2 3.4 i .o 2.1 0.s 7.9 0.3 3.0 0.1 2.3 0.5 2.7 i .0 3. i 1.6 3.6 0.6 2.8 0.6 3.0 0 0 3.9 20.7 13.1 56.0 209. i 7. i 107.0 0.c) 46. i 476.1 50.2 41 1.6 75.7 5.4 1 .o 5.7 4. i 3.0 3.(r 3.3 3.'j 5.0 7. i 1.2 4.4 0 30.' x7.0 are extremely limited, conclusions must be drawn with caution. nevertheles?, i t can be stated that levels of organochlorines and mercury found in grey plover eggs from the lena delta were low and far below levels considered embryotoxic (see scheuhammer 1987; becker, schuhmann et al. 1993). a comparison with eggs from other wader species breeding in northern n o w a y and along the german wadden sea coast from the mid-1990s, reveals (table 2 ) that the levels were on the same order of magnitude except for cpcb concentra tions being much lower in grey plover eggs, and about ten-fold higher chch levels consisting of 98% of /&hch. i n comparison, in eggs from waders breeding in the wadden sea /i-hch contributes only about 50-78% to the total hch concentration (becker, thyen et al. 1998). the ddt values as well as the ddt/dde ratio were also comparable to values in the wadden sea. whereas the high proportion of p-hch may indicate an actual input of hch from industrial sources into the lena delta. the d d t d d e ratio does not indicate a recent contamination of the birds by this pesticide. egg contamination may originate from both breeding and wintering sites. many studies of charadriifonn species indicate that the contamination of the breeding grounds is more important for egg contamination than that of the wintering areas (e.g. becker 1989; dietrich et al. 1997; becker, thyen et al. 1998). is this also valid for grey plovers breeding in the arctic, and migrating to southern asia or to europe and africa'? in our opinion this may indeed hold for grey plovers. especially with respect to hch. as has been shown by dietrich et al. (1997), who found that fland 7-hch levels in eggs of avocets (rrcunirostra czvosetta) originate from the breed ing grounds. but this has to be verified. the results of grey plover egg contamination are in line with pollutant studies in the neighbouring t u h k 2. geographical differences in mean contaminant conct'ntrations i n eggs of waders. given are mean levels of hg. y 8 pcb (see tahle i ); zhch, cddt = sum of six and four(*). re\pectively, metabolites o,p'-ddt, p.p'-ddt*, 0.p'-ddd, p,p'-ddd*. 0.p'-dde*, p,p'-dde*: and p,p'-dde. concentrations arc given in ng g . ' fresh egg mass (data from the literature were converted, see methods). hg c8 pcb chch /i-hch hcb cddt p,p'-dde source grey plover plui~icrlis sqirurcrrola 69 26 99 98 20 226 205 this paper lena deltdyakutia 1997 (ti = 3 ) dunlin cdidr-is d p i n n 93 i83 5 1 8 77" mattig 1998 northern norway 1993 ( 1 1 = 5 ) oystercatcher huemumpus 768 581 s 6 7 56 49 becker unpuhl. german wadden sea 1993 ( n = 10) avocet r < t l o y ~ ~ o s ~ ~ . ~ i u c w o w r i i i 50 150 5 4 15 190" 170 mattig et al. 1996 german wadden sea 1993 o r = 10) redshank tri'rzgn totunus 60 360 6 4 7 150* 150 mattig et al. 1996 germnn wadden sea 1993 ( n = 10) osrrulegus data exo et 31. 2000: polar rrserirch 19(2). 261-265 263 laptev sea (melnikov & vlasov 1990 cited in dethleff et al. 1993). these investigations indicate comparatively high concentrations of pcb. hch, the ddt group and phc (petroleum hydrocar bons) in sea water as well as in sea ice (dethleff et al. 1993). the lena delta itself is only sparsely populated; inhabitants are mainly engaged in fishing and hunting. besides an old coal mine at tiksi, there is no industry in the delta. though wind as a potential long-range transport vector for environmental chemicals and heavy metals has been documented repeatedly (e.g. muir et al. 1995; steinness 1997; amap 1998). huge amounts of the chemicals found in the delta are probably derived from sedimentation of transported fluvial material (dethleff et al. 1993; rachold et al. 1995; savinova et al. 1995; utschakowski 1998). the lena river discharges annually about 10 20 x lo6 t of sediment into the delta. for instance, the similarity of the pcb congener ratio from sea water and sediment samples to those of the russian commercial pcb mixture “sovol” indi cate a riverine transport into the delta (utscha k o w s k 1998). whereas outside the breeding season grey plovers mainly prey on polychaetes, during breeding they feed primarily on insects (byrkjedal & thompson 1998). this may explain why the insecticides ddt and hch had the highest concentrations among the environmental chemi cals analysed (table 1). both ddt and hch contamination in the study area may derive from use i n yakutia in former times as well as from elsewhere in asia. ddt was used in yakutia to control aedes midges, especially in reindeer breeding areas, up to the end of the 1960s (degtyarev 1997). whereas agricultural use of ddt was banned in the former soviet union in 1970 (amap 1998). ddt is still in use elsewhere in asia (see kucklick et al. 1996). hch is generally known as one of the dominant persistent organochlorine pesticides in arctic air and sea water (savinova et al. 1995; amap 1998). with china and india, the former soviet union was a leading hch-utilizing country. according to degtyarev (1997). from 1970 to 1995 about 3000 t of hch were used for agricultural purposes in addition to other pesticides in yakutia, mainly in the alas-type taiga between the lena and the amga. the drainage basin of the lena reaches up to lake baikal. the relatively high hch pollution of the sea water (1.66 ng g-’ , melnikov & vlasov 1990 cited in dethleff et al. 1993) may be responsible for the comparatively high hch levels in grey plover eggs; parts of the delta are regularly flooded. arctic ecosystems are particularly sensitive to perturbations. additional studies are needed to document the present situation with respect to pollution (savinova et al. 1995: amap 1998). because of their relatively high position in the food web and their vulnerability to persistent pollutants, waders are good bioindicators of environmental chemicals. they should therefore be included in an overall arctic monitoring programme, along with fish-eating birds and birds of prey. due to the impact of the river lena on the arctic ocean and the outstanding ornithological importance of the delta, we recommend the lena delta as one reference area. a l , k n o , ~ , l e ~ , q e , n m t s . thanha go to v. pozdnyakov and s. s. lsakovt of the lena nordenskiold international biological station (ibs). to d. n. gorokhov ofthe ust-lenaky state nature reserve and lena delta national nature reserve. and to p. prokosch. p. tomkovich and h. kassens, who helped to organize the expedition and arranged a lot of coiitacts. 1 . hertzler and 0. stepanova helped with the fieldwork and commented on an earlier draft. r. muratov. s. aleksanov’ and v. illus cared for us at ibs. the analytical work was supported by the niedersachsische wattenmeerstiftung and was done in cooperation with k. r. schmieder at the institut fur technisch wisserischaftliche innovation. fachhochschule wilhelmshaven. references wssincnr rrporrt arcti(. pollirrion i s s i r c ~ toring and assessment programme (amap). ballschmiter, k. & zell, m. 1980: analysis of polychlorinated biphenyls (pcb) by glass capillary gaschromatography. frrseiziirs 2. anirl. chem 302. 20-3 i , becker, p. h. 1989: seabirds as monitor organisms of contaminants along the german north sea coast. helga liiridrr mrerrsunrer. 43, 395403. becker, p. h., heidmann, w. a,, biithe, a., frank, d. & koepff, c. 1992: umweltchemikalien in eiern v a n brutvogeln der deutschen nordseekuste: trends 198 1-1990. (chemical residues in eggs of birds from the southern c ~ i l s t of the north sea: trends 1981-1990.) j . o m i r h f . 133. 109-121. becker, p. h.. schuhinann. s. & koepff. c. 1993: hatching failure i n common terns (srrrnu hirroiifoo) i n relation to environmental chemicals. enviroi?. p o l b i t . 79, 207-2 13. beckrr, p. h., thyen, s . . mickstein. s., sonin schmieder, k. r. 1998: monitoring pollutants i n c eggs in the wadden sea. wirdrlrii sra eco\.v.\t. 8, 55-95. wilhelmshaven: common wadderi sea secretariat. bipnert. a,, litren, k . . odsjo, t.. olsson, m., persaon, w . & reutergardh. l. 1995: time-related factors influeiice the concentrations of sddt, pcbs and shell parameters of baltic guillemot (uric1 r i r i l g r ) . 1861-1989. owiron. p d l i r t . 89. 27 36. 264 o r g a n o c h l o r i n e and mercury concentrations in egg, of grey plovers byrkjedal. 1. & thompson. d. b. a. 1998: tirndru plovtvx the, eiircrsiun, prrcific and aniericirri golden plovers ant1 ,err! ploiw. london: poyser. degtyarev, v . g. 1997: khlororganicheskiye soyedineniya v ecosisteniakh yakutii. (organochlorine compounds i n eco systems of yakutia.) i n 1. y. egorov & v. f. chernyavsky (eds. ): v o p r i ~ s x regionulnoi gigiyeny. soniturii i epiderniolo q i i . (probletns qf wgionul hygiene. .strnitution und epiilenriol ogx. proceeding.\ of the stare corntnirree on sunifurv control, issue 4. pp. 62-64. yakutak: state committee of republic sakha (yakutia) on sanitary control. dethleff. d., nurnberg, d., reimnitz. e.. snarso. m. &r savchenko, y . p. 1993: east siberiari arctic expedition 1992: the laptev sea ~ its significance for arctic sea-ice formation and transpolar fediment flux. ber. p o l i i r f i ~ r . ~ c h . 120, 3 4 1 . dietrich. s . , buthe, a,. denker. e. 6: hiitker. h. 1997: organochlorines i n eggs and food organisms of avocet\ ( r w x i n i r o s r r u ni'osettu). bull. eiiviron. confirm. tmic~ol. 58. 2 19-226. exo, k.-m. & stepanova, 0. 2000: ecology uf gre? ploi~,rv plrniuli.\ .syrrcrrur.olu breeding in the leriu delrii, the. sukhu r i ~ p i r h l i c / y a ~ i r r i i ~ in 1997. r i p m on u pilot stud!. wiwo rep. 69. zeist, netherlands: founckation working group international waterbird and wetland research. furness. r. w . 1993: birds as monitors of pollutants. in r. w. furness & j. j . d. greenwood (eds.): eirdv u s nionitor\ (j/ pttvirorinienrul chunge. pp. 86143. london: chapman kc hall. gilbertson. m., elliott, j . e. & peakall. d. b. 1987: seabird\ a \ indicators of marine pollution. i n a. w . diamond & f. l. filion (eds.): the idite of birds. internarionul council ~ o v eird preset-iwrion tech. pirhl. 6, 23 1-248. gilg, o., sane, r.. solovieva. d. v., pordnyakov. v. i., sabard. b.. tsanos. d.. ziickler. c.. lappo, e. g., syroechkonki. t. e.. jr. & eichhorn, g. 2000: birds and mammals of the lena delta nature reserve. siberia. arctic, 53. 118-133. koch, r. 190 i: urnrrelrclzt.ri~ietcrlien. (environmrnrul themi d s . ) wiesbaden: verlagsgesellschaft chemie. kruse, r. 1979: ein verlustfreier offener aufschlub mit hnoi. hcio?, hc104 fur die bestimniung von gesamt-quecksilber i n fischen. (determination of total mercury iii fish by nieanb of n digestion method with hno~lhciozlhcioj which lead> to low results.) z. lehmsni. utirers. for.sch. 16y. 259-261. kucklick. j . r.. harvey. h. r.. ostrom. p. h., ostrom, n . e. kc baker, j . e. 1996: organochlorine dynamics i n the pelasic food web of lake baikal. etwiron. tuicul. chew. 15, 13x8 1400. laboutin, y. v.. degtyarev. a. g. & blokhin. y. y. 1985: ptitsy. (birds.) in: r t r s t i f r l n ~ i : h i w t i i y inir d e l n reki len?. (floru und fuirtiu i n the lenu river delru.) proceeding.\ oftlic institure for biology. pp. 88-1 10. yakutsk: nauka puh1.i yakutsk branch. siberian department of ussr academy of sciences. mattig. f. r. 1998: die bedeiirun,y w n unri~~eltchrmiknlirri ~ i j i lehcvi.s~ykln.s 1'017 wirfvijgeln a m beispiel drs alpensrrirrid liiuf'er (culidris ulpiriu ulpinu). ( t h e significuncr o f e n i ~ i r o w nienrd c~hemicnls in rhe life-cycle of' ivnder.s iii the dirtdin [culidris d p i i i a olpinu] us a n esuniple.) berlin: wissenschaft & technik verlag. mattig. f. r.. becker, p. h., bietz. h. & giering, k. 1996: sclin~l.rti?l/clnrc~icherirrtg ini nrrhnrngsrietz des wirttenineeres. (arcnniit/urioti qf'etii3irontnenld c1~emicul.s in the food web of fhe wudilen sen. 1 uinrvelrbundesuntt res. rep. 10802085/2 1. tp a4.5. berlin: federal environmental agency. muir, d. c. g.. grift, n. p., lockhart, w. l., wilkinson, p.. billeck. b. n. & bmnskill. g. j. 1995: spatial trends and historical profiles of organochlorine pesticides in arctic lake sediments. sci. tofu1 entiiron. 160/161. 4 4 7 4 5 7 . newton. i. & wyllie. i. 1992: recovery of a sparrowhawk population in relation to declining pesticide contamination. j. appl. e d . -79, 4 7 6 4 8 4 . pozdnyakov. v . i.. solovieva, d. v. & sofronov. y. n. 1996: r:hunloohru:nye delry reki len?. ( c h a r u d r i i f o r t n e ~ in the lenu river delru.) in v. n. vasiliev & v. i. pozdnyakov (eds.): p i d t r : ~ . rusriteliiy i ;hivotnj niir urkriche.rkikh royoriov yirkurii fdelro r. l e i i y ) . ( s o i l s , jloro und juirtiu in arcric yukrrtiu ( t h e lenu river. delru]). pp. 54-64. yakutsk: russian academy of science. prokosch, p. 1995: lena delta/new siberian islands: inaugura tion of biological station and reserve extension. w w f arctic brrllerin 2/y5, 15. prokosch. p. 1997: nature reserve development i n russia. w w f arctic eirlletin 1/97, 12-14. rachold. v . . hermel. j. & korotarv, v. n. 1995: expedition to the lena river july/august 1994. ber. poluifursch. 182, 185-1 9s. ratcliffe. d. a. 1967: decrease i n eggshell weight i n certain birds of prey. nature 215. 208-210. rees. w. g. & kapitsa. a. p. 1994: industrial pollution in the kol'skiy poluostrov. russia. p o l a r r e c . 30. 181-188. savinova, t. n., gabrielsen. g. w. & falk-petersen. s. 1995: chemical pollution i n the arctic and sub-subarctic marine ecosystems: an overview of current knowledge. n i n a ficgrupport 1, 1-68. trondheim: norwegian foundation for nature research. scheuhammer. a. m . 1987: the chronic toxicity of aluminium, cadmium, mercury and lead i n buds: a review. e m i r o n . pullirr. 46, 263-295. solomonov, n. g. 1995: lena delru reserve. yakutsk: ministry of ecology and natural use. sommer. u., schmieder, k. r. & becker. p. h. 1997: untersuchungen von seevogeleiern auf chlorierte pestizide, pcbs und quecksilber. (analysis of sea bird eggs on chlorinated pesticides. pcbs and mercury). bioforurn 20/3. 68-72. steinness, e. 1997: pathways and effects of contaminants in the arctic. in s. woodin & m. marquiss (eds.): e c o ~ o ~ ~ o f a r c r i c envirunnienrs. pp. 209-217. oxford: blackwell. utschakowski. s. 1998: atfthropogetw orgunische spurensrqfe i r n arkrischen ozeuri. (anrhropogenic organic residues in the arcric o c e a n . ) phd thesis, university of kiel. exo et al. 2000: polnr resecirch isi(2i. 261-265 265 no job name from the institute’s photo librarypor_159 141 doi:10.1111/j.1751-8369.2010.00159.x hanna marie resvoll-holmsen (1873–1943) poses in front of a glacier debouching into the fjord lilliehöökfjorden, a branch of krossfjorden, in western spitsbergen, in 1908. the pioneering norwegian botanist carried out fieldwork in the arctic archipelago of svalbard during expeditions sponsored by prince albert i of monaco in 1907 and 1908. resvollholmsen was put ashore with her tent and provisions at remote locations along the coast. she worked industriously, mapping vegetation on the western side of spitsbergen, discovering new species and laying groundwork for subsequent investigations of the archipelago’s plant communities. resvoll-holmsen thrived on her solitude in the harsh wilderness. alone in her little camp in colesbukta, she wrote: “time passes far too quickly. tent life is wonderful . . .” a skilled photographer, resvoll-holmsen was among the first norwegian scientists to make use of colour photography, which she first experimented with in svalbard. the norwegian polar institute’s photo library preserves some 90 000 polar-related images captured during the last 135 years, including glass plates and slides, stereo images, print photographs and modern digital photographs. images documenting norwegian activities in the arctic and antarctic comprise the bulk of the collection. scanning the older images and registering newer digital ones is an ongoing endeavour. to date, digital versions of over 30 000 pictures are available in a searchable online database at http://sivert.npolar.no/fotoweb/. search words associated with the online images are mostly in the norwegian language; please send an e-mail to bildearkiv@npolar.no for assistance in searching the database. polar research 29 2010 141 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 141 http://sivert.npolar.no/fotoweb mailto:bildearkiv@npolar.no doi:10.3402/polar.v32i0.18521 r e s e a r c h / r e v i e w a r t i c l e effects of temperature and fertilization on the structure of total versus active bacterial communities from sub-antarctic seawater exposed to crude oil and diesel fuel arturo rodrı́guez-blanco,1,2,3 audrey duval,1,2 emilien pelletier,4 daniel delille1,2 & jean-françois ghiglione1,2 1 microbial oceanography laboratory, pierre and marie curie university paris 6, umr 7621, avenue fontaulé, bp44, fr-66650 banyuls-sur-mer, france 2 national center for scientific research, mixed research unit 7621, avenue fontaulé, bp44, fr-66650 banyuls-sur-mer, france 3 department of microbiology, institute for aquaculture, university of santiago de compostela, es-15782 santiago de compostela, spain 4 institute of marine science, university of quebec at rimouski, 310 allé des ursulines, rimouski, quebec g5l 3a1, canada keywords oil hydrocarbons; inipol eap 22; temperature; 16s rdna/rrna; sub-antarctic seawater. correspondence jean-françois ghiglione, national center for scientific research, mixed research unit 7621, avenue fontaulé, bp44, fr-66650 banyuls-sur-mer, france. e-mail: ghiglione@obs-banyuls.fr abstract polar environments are exposed to the risk of oil pollution. however, there is limited knowledge regarding how the variation of physicochemical factors influencing biodegradation may affect bacterial community structure. the effects of temperature (4, 10 and 208c) and organic fertilization (inipol eap 22) on community structure and diversity of bacteria inhabiting kerguelen sub-antarctic waters were studied in crudeand diesel-amended microcosms. dynamics of total (i.e., 16s rdna-based) and metabolically active (i.e., 16s rrna-based) bacterial community structure and diversity were monitored using capillary-electrophoresis single-strand conformation polymorphism. results showed that total and active community structures were differently influenced by temperature and fertilization in the presence of hydrocarbons. both fertilization and temperature induced changes in total community structure in the presence of crude oil and diesel. however, temperature showed a limited influence on active community structure, and fertilization induced changes in the presence of crude oil only. simpson’s index decreased for total bacterial communities at all temperatures in the presence of crude oil and diesel, whereas a lower reduction was observed for active bacterial populations. in the presence of fertilizer, the diversity of the whole community approached control values after seven incubation weeks; this was not observed for the active bacterial community. this study evidenced qualitative differences in total and active bacterial community structures of kerguelen seawaters in the presence of hydrocarbons and different responses relative to variation in temperature and fertilization. these factors and hydrocarbons composition have to be taken into account to understand bacterial community dynamics after an oil spill. increased ship traffic resulting from scientific, tourist and oil exploration activities in polar areas may have important environmental impacts, as shown by the shipwreck of the supply ship bahia paraiso near palmer station in antarctica (karl 1992). hydrocarbon degradation in natural environments is mainly achieved by microorganisms (leahy & colwell 1990). in antarctic environments, evidence of oil biodegradation by microorganisms has been shown in soils (wardell 1995), sediments (tumeo & wolk 1994), sea ice (delille et al. 1997) and seawater (delille et al. 1998). different environmental factors determine the extent of microbial degradation of hydrocarbons, nutrient availability and temperature being those considered to have a major (page number not for citation purpose) polar research 2013. # 2013 a. rodrı́guez-blanco et al. this is an open-access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2013, 32, 18521, http://dx.doi.org/10.3402/polar.v32i0.18521 http://www.polarresearch.net/index.php/polar/article/view/18521 http://dx.doi.org/10.3402/polar.v32i0.18521 impact in this process (atlas & bartha 1972; braddock et al. 1997; xia et al. 2006). nutrient availability is a limiting factor since hydrocarbons are characterized by high carbon to nitrogen and phosphorous ratios that do not support microbial growth, unless available nutrients correct this imbalance (head et al. 2006). the addition of fertilizers after oil pollution events has shown increased hydrocarbon degradation rates in cold environments (bragg et al. 1994) by enhancing both saprophytic and hydrocarbon-utilizing microbiota (delille et al. 1998). temperature influences microbial community structure and metabolism (nedwell 1999), especially in high-latitude regions (gerdes et al. 2005), but it also determines hydrocarbon physical state and bioavailability (leahy & colwell 1990). low temperatures increase oil viscosity and reduce volatilization of toxic short-chain alkanes, which delays biodegradation (leahy & colwell 1990). enzymatic activity is generally reduced at low temperature, resulting in a decrease in hydrocarbon degradation rates (leahy & colwell 1990). changes in bacterial community structure can be monitored using culture-independent techniques, since hydrocarbon-degrading bacteria frequently do not grow on common culture media (deppe et al. 2005). community structure has been monitored in cold environments after an oil exposure, but different hydrocarbon mixtures have rarely been tested under the same conditions (brakstad & lødeng 2004; gerdes et al. 2005; brakstad et al. 2008). studies have monitored changes in oilexposed community structure of arctic soil at different temperatures (eriksson et al. 2001) and in different fertilization conditions (yergeau et al. 2009). however, the simultaneous study of these two parameters in seawater community structure has been made in temperate environments only (coulon et al. 2007; rodrı́guezblanco et al. 2010). in a recent work, we studied the effect of temperature and fertilization on microbial growth and hydrocarbon degradation in sub-antarctic seawaters of the kerguelen archipelago exposed to crude and diesel oil mixtures (delille et al. 2009). the present study analyses the structural changes occurring in the bacterial communities of the kerguelen experiment, using a cultureindependent technique named capillary-electrophoresis single strand conformation polymorphism (ce-sscp; lee et al. 1996), targeting 16s rdna and 16s rrna. the use of a high-throughput fingerprinting technique, such as the ce-sscp, permits the comparison of a large number of samples (ghiglione et al. 2005), providing an accurate inter-sample analysis (hong et al. 2007). recently, ce-sscp has been shown to provide similar results compared to other fingerprinting techniques (ducklow et al. 2011) and to next generation sequencing techniques (ghiglione & murray 2012). metabolically active bacteria contain more rrna than resting or starved cells, and 16s rrna-based fingerprinting has been suggested as an indicator of the metabolically active bacterial community structure (delong et al. 1989; kemp et al. 1993; poulsen et al. 1993). the importance of focusing not only on the total bacterial community (based on 16s rdna) but also on the metabolically active fraction (based on 16s rrna) to evaluate the influence of environmental factors on bacterial populations has been underlined in previous studies (schafer et al. 2001; troussellier et al. 2002; moeseneder et al. 2005; gentile et al. 2006; lami et al. 2009; rodrı́guez-blanco et al. 2009). to our knowledge, only one study used a combined 16s rdna/16s rrna approach to compare dynamics of total versus metabolically active bacterial community structure of hypersaline microbial mats in the context of hydrocarbons pollution (bordenave et al. 2007). here, we present the first study testing the effects of temperature and fertilization on both total (dna-based) and active (rna-based) bacterial communities inhabiting sub-antarctic seawaters when subjected to crude oil and diesel fuel. materials and methods experimental set-up seawater was collected on 13 april 2006 at the surface, in the morbihan bay of the kerguelen archipelago (498 22? s, 708 12? e), 2 km from the port-au-français scientific station. samples were immediately carried to the biological laboratory of this station, where the experiments were conducted. seawater samples (600 ml) were added to sterile 1l-erlenmeyer flasks, together with 0.5 ml of either arabian light crude oil or diesel fuel. oil was added alone to seawater or with inipol eap 22 organic fertilizer (10% v/v; elf atochem, colombes, france). the arabian light crude used in this experiment was liquid petroleum with a high american petroleum institute gravity (328), a low pour point of �288c and a low dynamic viscosity of 31 cp at 08c. the inipol eap22 is a micro-emulsion containing butoxyethanol, oleic acid and surfactants with a dynamic viscosity of 250 cp at 208c and a pour point at 118c. one flask for each treatment (i.e., non-amended seawater; seawater amended with crude oil only; seawater amended with crude oil and inipol eap 22; seawater amended with diesel fuel only; seawater amended with structure of total versus active bacterial communities exposed to hydrocarbons a. rodrı́guez-blanco et al. 2 (page number not for citation purpose) citation: polar research 2013, 32, 18521, http://dx.doi.org/10.3402/polar.v32i0.18521 http://www.polarresearch.net/index.php/polar/article/view/18521 http://dx.doi.org/10.3402/polar.v32i0.18521 diesel fuel and inipol eap 22) was incubated at three different temperatures (20, 10 and 48c) for 7 weeks under orbital stirring. dna extraction and purification a minimum of 50 ml of seawater was pre-filtered through a 3 mm-pore filter (47 mm, polycarbonate nuclepore†, whatman, kent, uk) in order to remove large organisms and then filtered through a 0.22-mm pore filter (47 mm, polycarbonate nuclepore) before being stored at �808c until analysis. cellular lysis was performed in two steps on a lysis buffer, containing 50 mm trizma base (sigma-aldrich, st. louis, mo, usa), 40 mm ethylenediaminetetraacetic acid (sigma-aldrich) and 0.75 m sucrose (sigma-aldrich). first, a freshly prepared lysozyme solution (final concentration 1 mg ml �1 ) was added to the 0.22-mm pore filter and samples were incubated at 378c for 45 min. second, sodium dodecyl sulphate (final concentration 1%) and proteinase k (final concentration 0.2 mg ml �1 ) were added and tubes were incubated at 508c for 1 h. a volume of 600 ml of the resulting cellular lysate was treated with 10 ml of a 100 mg ml�1 rnase a solution (qiagen, hilden, germany) before dna extraction which was carried out using the dneasy tissue kit (qiagen), as described by the manufacturer instructions. rna extraction and cdna synthesis samples for rna analysis were processed in parallel to dna extraction as previously described (ghiglione et al. 2009). briefly, the remaining 400 ml of cellular lysate was treated with dnase i for rna extraction using an sv total rna isolation kit (promega, madison, wi, usa). effective dna digestion was verified before cdna synthesis by negative 16s rdna polymerase chain reaction (pcr) amplification (pcr conditions as reported below). rna was reverse transcribed (rt) into single-strand cdna using moloney murine leukemia virus (m-mlv) reverse transcriptase (promega), according to the manufacturer’s instructions. pcr amplification of cdna was carried out as for dna (see below). pcr-ce-sscp fingerprinting the highly variable v3 region (e. coli 16s rrna gene positions 329-533; brosius et al. 1981) of the 16s ribosomal rrna gene (16s rdna) was amplified for both dna and cdna extracts. the bacterial universal primer set w49 forward (5’acg gtc cag act cct acg gg-3’; delbès et al. 2001) and w34 reverse (5’-tta ccg cgg ctg ctg gca c-3’; lee et al. 1996) were used. the reverse primer was fluorescently labelled with 5’-tetrachloro-fluorescein-ce phosphoramidite (tet, applied biosystems�life technologies, norwalk, ct, usa) at the 5’-end position. pcr amplification of 50-ml reactions containing template, primers (final concentration 0.25 mm), dntps (eurogentec, seraing, belgium; final concentration 0.6 mm), pfu dna polymerase (1 u, promega) and pfu reaction buffer was run in a robocycler thermocycler (stratagene, agilent technologies, santa clara, ca, usa). pcr steps were initial denaturation at 948c for 1 min, followed by 25 cycles of denaturation at 948c for 1 min, annealing at 618c for 15 s and extending at 728c for 30 s with a final 10 min extension at 728c. size (ca. 200 bp length) and concentration of pcr products were determined by agarose gel electrophoresis (2%) with a dna size standard (low dna mass ladder, gibco�life technologies, carlsbad, ca, usa). successive dilutions in nuclease-free sterile water were made to obtain 10 ng ml�1 of pcr product. one ml of the dilution was mixed with 18.9 ml of formamide and 0.1 ml of the internal size standard gene-scan-400 rox (applied biosystems), denatured at 948c for 5 min, and immediately cooled on ice for 5 min before electrokinetical injection (5 s, 12 kv) into a capillary tube (47 cm �50 mm) filled with 5.6% of genescan polymer in a abi prism 310 genetic analyser (applied biosystems). electrophoresis was carried out at 15 kv for 30 min sample �1 at 308c, and data were collected with abi prism 310 collection software (applied biosystems). tet-labelled fragments were detected by a laser with a virtual c filter (detection wavelengths: 532, 537 and 584 nm). ce-sscp fingerprints comparative analysis total fingerprinting area was normalized among all the aligned ce-sscp profiles obtained using the internal size standard gene-scan-400 rox throughout the statistical analysis of fingerprints using molecular biology (safum) software (zemb et al. 2007). similarity matrices based on bray-curtis distances and unweighted pair group method with arithmetic mean (upgma) dendrograms were generated using the primer-e5 software package (clarke & warwich 2001). one-way anosim tests for significant differences in bacterial community structure were also performed using primer-e5. peak detection and simpson index values were automatically obtained from each fingerprint using the safum software. a. rodrı́guez-blanco et al. structure of total versus active bacterial communities exposed to hydrocarbons citation: polar research 2013, 32, 18521, http://dx.doi.org/10.3402/polar.v32i0.18521 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18521 http://dx.doi.org/10.3402/polar.v32i0.18521 results comparative analysis of the structure of total bacterial communities (16s rdna) in samples collected during microcosm experiments 16s rdna-based fingerprints of samples incubated with the oleophilic fertilizer clustered separately from those incubated only with crude or diesel oil (fig. 1a, clusters 3 and 7, and fig. 1b, clusters 6 and 7), suggesting nutrients addition to induce changes in total bacterial community structure. however, these changes occurred mostly at high temperatures (i.e., 108c and 208c), since fertilizer-enriched incubations made at low temperature (i.e., 48c) induced mostly no variations in structure (fig. 1a, clusters 3 and 4, and fig. 1b, clusters 4 and 5). in the presence of crude oil, fertilizer-induced bacterial community structure changed between the first and the seventh week of incubation, with similar changes observed at 10 and 208c (fig. 1a, clusters 3 and 7). conversely, fertilizer-induced structure remained stable over time in the presence of diesel (from the third week at 108c), but with separated clusters obtained at 10 and 208c (fig. 1b, clusters 6 and 7). compiling all data, fig. 1 unweighted pair group method with arithmetic mean dendrograms based on bray-curtis similarities among 16s rdna capillary-electrophoresis single strand conformation polymorphism profiles in the presence of (a) arabian light crude oil and (b) diesel fuel incubations. the initial community (to); non-amended controls (squares); samples amended with crude oil (circles) or crude oil with inipol eap 22 (inverted triangles) and samples amended with diesel oil (rhombs) or diesel oil with inipol eap 22 (triangles) are shown for incubation temperatures of 48c (white), 108c (grey) and 208c (black). dashed lines indicate cut-off similarity value, which were assigned to 50�60% for adequate cluster definition. structure of total versus active bacterial communities exposed to hydrocarbons a. rodrı́guez-blanco et al. 4 (page number not for citation purpose) citation: polar research 2013, 32, 18521, http://dx.doi.org/10.3402/polar.v32i0.18521 http://www.polarresearch.net/index.php/polar/article/view/18521 http://dx.doi.org/10.3402/polar.v32i0.18521 anosim tests showed weak structural differences induced by inipol eap 22 in diesel incubations (global r �0.145; significance level of sample statistic �3.7%), and no differences in crude oil incubations. (global r �0.067; significance level of sample statistic �16.4%). clusters containing mainly samples incubated at the same temperature were more frequently observed in the diesel-related dendrogram (fig. 1b, clusters 2�6) than in the crude oil-related dendrogram (fig. 1a, cluster 6), indicating the influence of temperature on total community structure to be more important in the presence of diesel. anosim tests confirmed these temperature-related structural differences in all diesel incubations (global r �0.1; significance level of sample statistic �12.3%), and for crude oil incubations the absence of such differences (global r �0.024; significance level of sample statistic �33.3%). in fact, a slight different impact of oil mixture alone was observed for the total bacterial community structure. crude oil-addition induced structural changes at all temperatures, as shown by separate clusters containing controls and crude oil-amended samples (fig. 1a, clusters 1 and 2). however, a simple diesel addition caused no systematic changes in the structure of total bacterial communities (fig. 1b, clusters 2 and 3). the structure of initial bacterial communities was similar to that of non-amended controls incubated at 48c, from the first to the seventh week of incubation (fig. 1a, b, cluster 1). this indicates a low impact of confinement in bacterial community structure along the study. comparative analysis of the structure of active bacterial communities (16s rrna) in samples collected during microcosm experiments the 16s rrna-based dendrogram provided different results in the ongoing dynamics of the active bacterial fraction. samples collected after 1 and 3 weeks, including non-amended controls, strongly resembled one another, constituting well separated clusters in both crude oil and diesel-related dendrograms (fig. 2a, cluster 1; fig. 2b, cluster 2). the sample corresponding to the initial communities clustered separately from these clusters (fig. 2a, b). differences in active community structure related to time of incubation were significant in both crude oil (global r �0.228; significance level of sample statistic �0.2%) and diesel incubations (global r � 0.498; significance level of sample statistic �0.1%). samples incubated in the presence of fertilizer primarily clustered separately from those incubated in the presence of crude oil only (fig. 2a, clusters 1, 2, 5 and 6), whereas they mostly clustered together with those incubated with diesel only (fig. 2b, clusters 2, 3 and 5). thus, fertilization induced changes in active community structure depending on the oil mixture tested, but temperature had a low influence on structure: no temperature-related clusters were found either in crude oil or in diesel fuel-related 16s rrna-based dendrograms (fig. 2). comparative analysis of simpson’s index values obtained from ce-sscp fingerprints of total (16s rdna) and active (16s rrna) bacterial communities simpson’s index values of 16s rdna and 16s rrna cesscp fingerprints obtained from crude oil and diesel amended cultures were relativized to values obtained from non-amended controls (fig. 3). relative simpson’s index values of total bacterial communities (16s rdna) initially decreased in the presence of both crude oil and diesel at 108c and 208c (fig. 3a, c), whereas this reduction occurred later on at 48c (fig. 3a, c), indicating some influence of temperature in diversity dynamics along the incubation period. diversity remained low after seven incubation weeks except at 108c in the presence of both crude oil and diesel. in the presence of fertilizer, the diversity of the whole community approached control values after seven incubation weeks, showing minor differences among temperatures (fig. 3b, d). regarding values for active bacterial populations, lower diversity reduction was generally observed after crude and diesel oil addition (fig. 3e, g). fertilizer addition tended to reduce diversity, and this reduction occurred earlier at 48c (fig. 3f, h). discussion in a previous article based on the same experiment as described here, we observed that bacterial growth and hydrocarbon degradation increased in the presence of fertilizer inipol eap 22, whereas temperature variation induced minor changes in growth and oil degradation (delille et al. 2009). the present study analysed changes in bacterial community structure during the same experiment, to understand whether the observed quantitative changes in growth and biodegradation also corresponded to some qualitative changes in community structure. although temperature range and substrate concentration have a crucial role to play in bacterial growth (pomeroy & wiebe 2001; kirchman et al. 2009), bacterial species tolerate different temperature ranges. a. rodrı́guez-blanco et al. structure of total versus active bacterial communities exposed to hydrocarbons citation: polar research 2013, 32, 18521, http://dx.doi.org/10.3402/polar.v32i0.18521 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18521 http://dx.doi.org/10.3402/polar.v32i0.18521 lower growth temperatures are mostly defined by the loss of membrane function, and upper growth temperatures are determined by denaturation of key cellular components (nedwell 1999). in the presence of hydrocarbons, only some species are responsible for a significant part of hydrocarbon removal (head et al. 2006), suggesting that fertilization would stimulate the growth of a limited fraction of the bacterial community, at least initially. considering temperature variation and substrate concentration together seems to be of high interest, since interactions between these two parameters may exist. for instance, substrate uptake or assimilation can be altered by temperature (pomeroy & wiebe 2001). inipol eap 22 is an oleophilic fertilizer that supplies organic nutrients in a slow release form, but it also has surfactant characteristics reducing oil viscosity and preventing the formation of water-in-oil emulsions (ladousse & tramier 1991). our results showed that fertilizer addition induced structural changes to the total bacterial community at higher temperatures (108c and 208c) in both crude or diesel oil conditions, whereas they induced changes in the active bacterial fraction only in the presence of crude oil. temperature had a more remarkable effect on total community structure in the presence of diesel, while no effect was detected in the structure of the active fig. 2 unweighted pair group method with arithmetic mean dendrograms based on bray-curtis similarities among 16s rrna rdna capillaryelectrophoresis single strand conformation polymorphism profiles in the presence of (a) arabian light crude oil and (b) diesel fuel incubations. the initial community (to); non-amended controls (squares); samples amended with crude oil (circles) or crude oil with inipol eap 22 (inverted triangles) and samples amended with diesel oil (rhombs) or diesel oil with inipol eap 22 (triangles) are shown for incubation temperatures of 48c (white), 108c (grey) and 208c (black). dashed lines indicate cut-off similarity value, which were assigned to 50�60% for adequate cluster definition. structure of total versus active bacterial communities exposed to hydrocarbons a. rodrı́guez-blanco et al. 6 (page number not for citation purpose) citation: polar research 2013, 32, 18521, http://dx.doi.org/10.3402/polar.v32i0.18521 http://www.polarresearch.net/index.php/polar/article/view/18521 http://dx.doi.org/10.3402/polar.v32i0.18521 community. these results point to the different dynamics of the total community as opposed to the metabolically active bacterial populations. the distribution of the total bacterial community was more dependent on temperature variation, even in the presence of inipol eap 22 when exposed to hydrocarbons. the distribution of active bacterial members was more related to factors playing an important role in degradation in the kerguelen experiment, such as availability of nutrients and hydrocarbon composition, which is consistent with the fact that metabolically active members are responsible for hydrocarbon degradation. comparable trends have been found in a similar experiment involving seawater from the mediterranean sea (rodrı́guez-blanco et al. 2010), suggesting a similar influence of temperature and nutrients in the presence of hydrocarbons for bacterial communities inhabiting polar and temperate seawaters. even though temperature fig. 3 simpson’s index values relative to (a)�(d) non-amended controls of 16s rdna and (e)�(h) 16s rrna capillary-electrophoresis single strand conformation polymorphism fingerprints obtained from (a) and (e) crude-oil-amended cultures; (b) and (f) cultures amended with crude oil and inipol eap 22; (c) and (g) diesel-oil-amended cultures; and (d) and (h) cultures amended with diesel oil and inipol eap 22. a. rodrı́guez-blanco et al. structure of total versus active bacterial communities exposed to hydrocarbons citation: polar research 2013, 32, 18521, http://dx.doi.org/10.3402/polar.v32i0.18521 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18521 http://dx.doi.org/10.3402/polar.v32i0.18521 usually ranges from 28c to 88c in coastal seawater off the kerguelen archipelago (delille et al. 2009), temperature can drop below zero in winter and rise above 188c on warm summer days. previous studies of kerguelen cultivable bacteria suggest that a diverse number of optimum temperature ranges could have been represented at the time of the experiment (delille & perret 1989), including tolerant psychrophilic bacteria (optimal temperature between 78c and 208c), psychrotrophic bacteria (between 48c and 308c) and tolerant psychrotrophic bacteria (208c or above). therefore, the similarity of behaviour between mediterranean and sub-antarctic seawater bacterial communities in the presence of hydrocarbons may occur only in specific seasonal periods. quite different from the kerguelen experiment, structural changes induced by fertilization at the rna level in the mediterranean experiment occurred in the presence of both crude oil and diesel fuel (rodrı́guez-blanco et al. 2010). kerguelen active community structure was less influenced by fertilization in diesel incubations (fig. 2). these qualitative differences related to hydrocarbon mixtures in kerguelen seawater were also observed in some quantitative data. biodegradation rates of less volatile hydrocarbons (c17/pristane ratio) indicated that fertilizer did not increase diesel biodegradation in the same way as it did for crude oil (delille et al. 2009). this could be related to the different influence of different hydrocarbon mixtures in the kerguelen bacterial community structure. other factors, such as the ability of the kerguelen bacterial communities to degrade certain compounds, could explain these differences between the degradation rates of crude oil and diesel fuel. results of 16s rrna-based dendrogram show an important influence of time of incubation on the structure of active bacterial communities (fig. 2). these dynamics were not observed at the dna level (fig. 1b). similar results have been observed using a combined 16s rdna/rrna approach to study the bacterial community of a pristine microbial mat exposed to heavy fuel oil (bordenave et al. 2007). these authors reported that changes of structure were observed earlier at the rna level than at the dna level. the relation among structure of the active bacterial community and time of incubation could be related to the modification in the hydrocarbons composition or other temporal changes occurring in natural environments as a result of biodegradation (head et al. 2006). for instance, aliphatic hydrocarbons are degraded before high molecular weight aromatic hydrocarbons (head et al. 2006). biodegradation of different hydrocarbon molecules at different times is the result of co-metabolic reactions involving different bacterial species (deppe et al. 2005). pelz et al. (1999) showed that initial hydrocarbon degrading bacteria were replaced by other populations with complementary degradation capacities, which could explain the temporal changes observed in the present study for active bacterial structure in the presence of hydrocarbons. temporal clusters of 16s rrna-based fingerprints were also observed in a similar study made on temperate estuarine waters (coulon et al. 2007). the very low viscosity and pour point of crude oil used in this experience ensured its bioavailability to microorganisms from the beginning of the experiment. inipol eap22 is relatively more viscous and has a high pour point, but it readily mixed with oil, did not change the low viscosity of the mixture and the presence of surfactants greatly enhanced the bioavailability of the oil. these results highlight the value of using a combined 16s rdna/rrna approach to study the dynamics of the bacterial community structure in the context of hydrocarbon pollution. monitoring structural changes in the bacterial community in the presence of hydrocarbons has usually been undertaken with 16s rdna-based approaches (head et al. 2006). however, limitations, such as variation in the rdna copy number among bacterial species that could introduce biased estimation of diversity and the lack of information related to cellular activity, make these approaches limited (klappenbach et al. 2000; acinas et al. 2004). 16s rrna-based approaches have their own limitations, including growth rate variation in natural environments inducing variation in the cellular rrna content (givskov et al. 1994). combining 16s rdna/rrna approaches provides a more complete and reliable description of the bacterial community structure. moreover, the use of a high-throughput fingerprinting technique, such as the ce-sscp, allows the comparison of a high number of samples (92), providing accurate inter-sample analysis (hong et al. 2007). the use of a capillary and standardized reagent with cesscp avoids problems related to gel-to-gel variation (hebenbrock et al. 1995) that would make other gelbased techniques, such as denaturing gradient gel electrophoresis, less suitable for the comparative analysis of our samples (hong et al. 2007). furthermore, no digestion with restriction enzymes is required in the ce-sscp technique, compared to other capillary-based fingerprinting methods, such as terminal restriction fragment length polymorphism, avoiding the putative incomplete digestions and subsequent formation of multiple peaks per operational taxonomic unit (mills et al. 2003). the current study was performed under field conditions that made the use of replicates impractical. structure of total versus active bacterial communities exposed to hydrocarbons a. rodrı́guez-blanco et al. 8 (page number not for citation purpose) citation: polar research 2013, 32, 18521, http://dx.doi.org/10.3402/polar.v32i0.18521 http://www.polarresearch.net/index.php/polar/article/view/18521 http://dx.doi.org/10.3402/polar.v32i0.18521 despite the lack of replicates, the results from this study showed that important information was obtained both at physicochemical and biological levels. the simpson diversity index showed that the addition of crude oil and diesel reduced the diversity in total bacterial communities. however, the reduction was retarded at 48c (fig. 3). the diversity of active bacterial communities experienced less marked changes after crude or diesel oil addition. these results are consistent with those observed in the mediterranean sea (rodrı́guezblanco et al. 2010). however, fertilization increased diversity of kerguelen total communities and decreased that of active populations, which was different from what we observed in the mediterranean sea. this could indicate that among metabolically active bacteria a few members would benefit from fertilization to perform hydrocarbon degradation (cappello et al. 2007). the present study evidenced qualitative differences in total and active bacterial community structures in the presence of hydrocarbons and the different responses relative to variation in temperature and fertilization. to fully understand the dynamics of the bacterial communities subjected to an oil spill in cold conditions, variations in hydrocarbon composition and fertilization have to be taken in account. acknowledgements arb was affiliated with the pierre and marie curie university and the national center for scientific research, in banyuls-sur-mer, france, at the time the research reported here was carried out. references acinas s.g., marcelino l.a., klepac-ceraj v. & polz m. 2004. divergence and redundancy of 16s rrna sequences in genomes with multiple rrn operons. journal of bacteriology 186, 2629�2635. atlas r.m. & bartha r. 1972. biodegradation of petroleum in seawater at low temperatures. canadian journal of microbiology 18, 1851�1855. bordenave s., goñi-urriza m.s., caumette p. & duran r. 2007. effects of heavy fuel oil on the bacterial community structure of a pristine microbial mat. applied and environmental microbiology 73, 6089�6097. braddock j.f., ruth m.l., catterall p.h., walworth j.l. & mccarthy k.a. 1997. enhancement and inhibition of microbial activity in hydrocarbon-contaminated arctic soils: implications for nutrient-amended bioremediation. environmental science & technology 31, 2078�2084. bragg j.r., prince r.c., harner e.j. & atlas r.m. 1994. effectiveness of bioremediation for the exxon valdez oil spill. nature 368, 413�418. brakstad o.g. & lødeng a.g.g. 2004. microbial diversity during biodegradation of crude oil in seawater from the north sea. microbial ecology 49, 94�103. brakstad o.g., nonstad i., faksness l.-g. & brandvik p.j. 2008. responses of microbial communities in arctic sea-ice after contamination by crude petroleum oil. microbial ecology 55, 540�552. brosius j., dull t.j., sleeter d.d. & noller h.f. 1981. gene organization and primary structure of a ribosomal rna operon from escherichia coli. journal of molecular biology 148, 107�127. cappello s., caruso g., zampino d., monticelli l.s., maimone g., denaro r., tripodo b., troussellier m., yakimov m. & giuliano l. 2007. microbial community dynamics during assays of harbour oil spill bioremediation: a microscale simulation study. journal of applied microbiology 102, 184�194. clarke k.r. & warwich r.m. 2001. primer-e (5) computer program. plymouth, uk: natural environmental research council. coulon f., mckew b.a., osborn a.m., mcgenity t.j. & timmis k.n. 2007. effects of temperature and biostimulation on oil-degrading microbial communities in temperate estuarine waters. environmental microbiology 9, 177�186. delbès c., godon j.j. & moletta r. 2001. bacterial and archaeal 16s rdna and rrna dynamics during an acetate crisis in an anaerobic digestor ecosystem. fems microbiology ecology 35, 19�26. deppe u., richnow h.h. & antranikian w.m.g. 2005. degradation of crude oil by an arctic microbial consortium. extremophiles 9, 461�470. delille d., bassères a. & dessommes a. 1997. seasonal variation of bacteria in sea ice contaminated by diesel fuel and dispersed crude oil. microbial ecology 33, 97�105. delille d., bassères a., dessommes a. & rosiers c. 1998. influence of daylight on potential biodegradation of diesel and crude oil in antarctic seawater. marine environmental research 45, 259�268. delille d., pelletier e., rodrı́guez-blanco a. & ghiglione j.f. 2009. effects of nutrient and temperature on degradation of petroleum hydrocarbons in sub-antarctic coastal seawater. polar biology 32, 1521�1528. delille d. & perret e. 1989. influence of temperature on growth potential of southern polar bacteria. microbial ecology 18, 117�123. delong e.f., wickham g.s. & pace n.r. 1989. phylogenetic stains: ribosomal rna-based probes for the identification of single cells. science 243, 1360�1363. ducklow h.w., myers k.m.s., erickson m., ghiglione j.f. & murray a.e. 2011. response of a summertime antarctic marine bacterial community to glucose and ammonium enrichment. aquatic microbial ecology 64, 205�220. eriksson m., ka j.o. & mohn w.w. 2001. effects of low temperature and freeze�thaw cycles on hydrocarbon biodegradation in arctic tundra soil. applied and environmental microbiology 67, 5107�5112. a. rodrı́guez-blanco et al. structure of total versus active bacterial communities exposed to hydrocarbons citation: polar research 2013, 32, 18521, http://dx.doi.org/10.3402/polar.v32i0.18521 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18521 http://dx.doi.org/10.3402/polar.v32i0.18521 gentile g., giuliano l., d’auria g., smedile f., azzaro m., de domenico m. & yakimov m.m. 2006. study of bacterial communities in antarctic coastal waters by a combination of 16s rrna and 16s rdna sequencing. environmental microbiology 8, 2150�2161. gerdes b., brinkmeyer r., dieckmann g. & helmke e. 2005. influence of crude oil on changes of bacterial communities in arctic sea-ice. fems microbiology ecology 53, 129�139. ghiglione j.f., conan p. & pujo-pay m. 2009. diversity of total and active free-living vs. particle-attached bacteria in the euphotic zone of the nw mediterranean sea. fems microbiology letters 299, 9�21. ghiglione j.f., larcher m. & lebaron p. 2005. spatial and temporal scales of variation in the bacterioplankton community structure in the nw mediterranean sea. aquatic microbial ecology 40, 229�240. ghiglione j.f. & murray a. 2012. pronounced summer to winter differences and higher wintertime richness in coastal sub-antarctic and antarctic marine bacterioplankton. environmental microbiology 14, 617�629. givskov m., eberl l., moller s., poulsen l.k. & molin s. 1994. responses to nutrient starvation in pseudomonas putida strain kt2442: analysis of general crossprotection, cell shape, and macromolecular content. journal of bacteriology 176, 7�14. head i.m., jones d.m. & röling w.f. 2006. marine microorganisms make a meal of oil. nature reviews microbiology 4, 173�182. hebenbrock k., williams p.m. & karger b.l. 1995. single strand conformational polymorphism using capillary electrophoresis with two-dye laser-induced fluorescence detection. electrophoresis 16, 1429�1436. hong h., pruden a. & reardon k.f. 2007. comparison of ce-sscp and dgge for monitoring a complex microbial community remediating mine drainage. journal of microbiological methods 69, 52�64. karl d.m. 1992. the grounding of the bahia paraiso: microbial ecology of the 1989 antarctic spill. microbial ecology 24, 77�89. kemp p.f., lee s. & laroche j. 1993. estimating the growth rate of slowly growing marine bacteria from rna content. applied and environmental microbiology 59, 2594�2601. kirchman d.l., moran x.a. & ducklow h. 2009. microbial growth in the polar oceans*role of temperature and potential impact of climate change. nature reviews microbiology 7, 451�459. klappenbach j.a., dunbar j.m. & schmidt t.m. 2000. rrna copy number reflects ecological strategies of bacteria. applied and environmental microbiology 64, 1328�1333. ladousse a. & tramier b. 1991. results of 12 years of research in spilled oil bioremediation: inipol eap 22. in: proceedings of the 1991 oil spill conference (prevention, behaviour, control, cleanup), march 4�7, 1991. pp. 577�581. washington, dc: american petroleum institute. lami r., ghiglione j.f., desdevises y., west n.j. & lebaron p. 2009. annual patterns of presence and activity of marine bacteria monitored by 16s rdna�16s rrna fingerprints in the coastal nw mediterranean sea. aquatic microbial ecology 54, 199�210. leahy j.g. & colwell r.r. 1990. microbial degradation of hydrocarbons in the environment. microbiological reviews 54, 305�315. lee d.h., zo y.g. & kim s.j. 1996. nonradioactive method to study genetic profiles of natural bacterial communities by pcr-single-strand-conformation-polymorphism. applied and environmental microbiology 62, 3112�3120. mills d.k., fitzgerald k., litchfield c.d. & gillevet p.m. 2003. a comparison of dna profiling techniques for monitoring nutrient impact on microbial community composition during bioremediation of petroleum-contaminated soils. journal of microbiological methods 54, 57�74. moeseneder m.m., arrieta j.m. & herndl g.j. 2005. a comparison of dnaand rna-based clone libraries from the same marine bacterioplankton community. fems microbiology ecology 51, 341�352. nedwell d.b. 1999. effect of low temperature on microbial growth: lowered affinity for substrates limits growth at low temperature. fems microbiology ecology 30, 101�111. pelz o., tesar m., wittich r.m., moore e.r.b., timmis k.n. & abraham w.-r. 1999. towards elucidation of microbial community metabolic pathways: unravelling the network of carbon sharing in a pollutant degrading bacterial consortium by immunocapture and isotope ratio mass spectroscopy. environmental microbiology 1, 167�174. pomeroy l.r & wiebe w.j. 2001. temperature and substrates as interactive limiting factors for marine heterotrophic bacteria. aquatic microbial ecology 23, 187�204. poulsen l.k., ballard g. & stahl d.a. 1993. use of rrna fluorescence in situ hybridization for measuring the activity of single cells in young and established biofilms. applied and environmental microbiology 59, 1354�1360. rodrı́guez-blanco a., antoine v., pelletier e., delille d. & ghiglione j.f. 2010. effects of temperature and fertilization on total vs. active bacterial communities exposed to crude and diesel oil pollution in nw mediterranean sea. environmental pollution 158, 663�673. erratum: environmental pollution 159, 348�350. rodrı́guez-blanco a., ghiglione j.f., catala p., casamayor e.o. & lebaron p. 2009. spatial comparison of total vs. active bacterial populations by coupling genetic fingerprinting and clone library analyses in the nw mediterranean sea. fems microbiology ecology 67, 30�42. schafer h., bernard l., courties c., lebaron p., servais p., pukall r., stackebrandt e., troussellier m., guindulain t., vives-rego j. & muyzer g. 2001. microbial community dynamics in mediterranean nutrient-enriched seawater mesocosms: changes in the genetic diversity of bacterial populations. fems microbiology ecology 34, 243�253. tumeo m.a. & wolk a.e. 1994. assessment of the presence of oil-degrading microbes at mcmurdo station. antarctic journal of the united states 29, 375�377. troussellier m., schafer h., batailler n., bernard l., courties c., lebaron p., muyzer g., servais p. & vives rego j. 2002. structure of total versus active bacterial communities exposed to hydrocarbons a. rodrı́guez-blanco et al. 10 (page number not for citation purpose) citation: polar research 2013, 32, 18521, http://dx.doi.org/10.3402/polar.v32i0.18521 http://www.polarresearch.net/index.php/polar/article/view/18521 http://dx.doi.org/10.3402/polar.v32i0.18521 bacterial activity and genetic richness along an estuarine gradient (rhone river plume, france). aquatic microbial ecology 28, 13�24. wardell l.j. 1995. potential for bioremediation of fuelcontaminated soil in antarctica. journal of soil contamination 4, 111�121. xia w.x., li j.c., zheng x.l., bi x.j. & shao j.l. 2006. enhanced biodegradation of diesel oil in seawater supplemented with nutrients. engineering in life sciences 6, 80�85. yergeau e., arbour m., brousseau r., juck d., lawrence j.r., masson l., whyte l.g. & greer c.w. 2009. microarray and real-time pcr analyses of the responses of high-arctic soil bacteria to hydrocarbon pollution and bioremediation treatments. applied and environmental microbiology 75, 6258�6267. zemb o., haegeman b., delgenes j.p., lebaron p. & godon j.j. 2007. safum: statistical analysis of sscp fingerprints using pca projections, dendrograms and diversity estimators. molecular ecology notes 7, 767�770. a. rodrı́guez-blanco et al. structure of total versus active bacterial communities exposed to hydrocarbons citation: polar research 2013, 32, 18521, http://dx.doi.org/10.3402/polar.v32i0.18521 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18521 http://dx.doi.org/10.3402/polar.v32i0.18521 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <feff005000440046002f0058002d00336e9662e0306e30ec30dd30fc30c87528304a30883073658766f84f5c62107528306b4f7f75283057307e30593002005000440046002f00580020306f30b030e930d530a330c330af30b3002030f330c630f330c4590963db306b304a3051308b002000490053004f00206a196e96306730593002005000440046002f0058002d003300206e9662e0306e658766f84f5c6210306b306430443066306f0020004100630072006f006200610074002030e630fc30b630ac30a430c9309253c2716730573066304f30603055304430024f5c62103057305f00200050004400460020306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200034002e003000204ee5964d30678868793a3067304d307e30593002> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu (settings for the rampage workflow.) >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice no job name release of reactive organic halogens by the brown macroalga saccharina latissima after exposure to ultraviolet radiationpor_167 379..384 frank laturnus,1 teresia svensson2 & christian wiencke3 1 institute for biogeochemistry and marine chemistry, university of hamburg, bundesstraße 55, de-20146 hamburg, germany 2 department of thematic studies—water and environmental studies, linköping university, se-60174 norrköping, sweden 3 alfred wegener institute for polar and marine research, am handelshafen 12, de-27570 bremerhaven, germany abstract the brown macroalga saccharina latissima (linnaeus) c.e. lane, c. mayes, druehl & g.w. saunders (formerly laminaria saccharina [l.] lamouroux) was exposed to ultraviolet radiation (uvr) in the mw uv-a and mw uv-b range in the laboratory for up to 28 days. the release rates of volatile organohalogens, such as chloroform, bromoform, dibromomethane and methyl iodide, were determined. from these rates, the total emission of reactive organic halogens was calculated. the results revealed that exposure to uvr significantly affected the emission of reactive organic halogens by the macroalga under investigation. an increase in the release of reactive organic iodine was observed for the algal species. in contrast, for reactive organic bromine and reactive organic chlorine, a decrease in emission by the macroalga was observed. apparently, the potential for increased levels of uvr resulting from further ongoing destruction of the stratospheric ozone layer may increase the importance of marine macroalgae in atmospheric reactions involving organic halogens. keywords climate changes; macroalgae; ozone destruction; reactive organic halogens; ultraviolet radiation. correspondence frank laturnus, institute for biogeochemistry and marine chemistry, university of hamburg, bundesstraße 55, de-20146 hamburg, germany. e-mail: frank.laturnus@zmaw.de doi:10.1111/j.1751-8369.2010.00167.x the increase of surface ultraviolet radiation (uvr) caused by the depletion of stratospheric ozone is still a major environmental concern. it is assumed that the level of uvr reaching the earth’s surface will continue to increase until the ozone layer recovers (e.g., shindell et al. 1998). the ongoing warming of the troposphere further supports atmospheric conditions involved in the destruction of stratospheric ozone over the polar regions (shindell et al. 1998). it is generally agreed that the depletion of stratospheric ozone is largely caused by the emission of reactive halogens derived from volatile organohalogens of anthropogenic and natural origin. once in the atmosphere, these organic halogens interfere with and modulate many chemical processes (daniel et al. 1999; solomon 1999). marine macroalgae are an important source of reactive organic halogens, especially in coastal ecosystems (carpenter & liss 2000; laturnus 2001). it is still not known exactly why macroalgae form volatile organic halogens, but it has been suggested that this process may be caused by oxidative stress (pedersén et al. 1996; weinberger et al. 2007). as uvr is known to cause stress in biota (franklin & forster 1997), it is possible that it could induce the formation of reactive organic halogens by these algae (e.g., laturnus et al. 2004). hence, elevated uvr may lead to a feedback loop in which higher emissions of organic halogens by algae lead to a further decrease of the ozone layer. the present study examines whether or not elevated levels of uvr cause an increased emission of reactive organic halogens by macroalgae. the brown algal species saccharina latissima was chosen for its widespread occurrence and high biomass in the arctic circle and other cold-temperate environments (lüning 1990). furthermore, brown algae are known to be the strongest accumulators of iodine among living organisms, and are considered to be a major pump in the global biogeochemical cycle of iodine (küpper et al. 2008). material and methods six-month-old plants of the brown macroalgal species s. latissima (linnaeus) c.e. lane, c. mayes, druehl & g.w. saunders were exposed to combined photosynthetic active radiation (par), uv-a and uv-b radiation under controlled laboratory conditions for 28 days. the algae were grown from spores of a sporophyte of s. latissima polar research 29 2010 379–384 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 379 mailto:laturnus@zmaw.de isolated in svalbard. the culture was unialgal, but not sterile. par was provided by one cool-white fluorescent neon tube (l58/w19, 23 mmol photons m-2 s-1, 700– 400 nm; osram, munich). uv-a (7.7 w m-2, 320– 400 nm) and uv-b (0.70 w m-2, 280–320 nm) were provided by two uv-a-340 fluorescence tubes (q-panel, cleveland, oh, usa). the photon flux of par was measured with a li-185 b quantum radiometer and a li-190 b 2p quantum sensor (li-cor biosciences, lincoln, ne, usa). uv-a and uv-b photon fluxes were measured with a solarlight pma 2100 broadband radiometer equipped with a uv-a sensor pma 2110 and a uv-b sensor pma 2106 (solarlight, philadelphia, pa, usa). surface uvr levels of around 19 w m-2 uv-a and 1.1 w m-2 uv-b are common on clear days at noon (bischof et al. 1998). the uvr applied in the experiment corresponds to 0.63 w m-2 weighted irradiance using the action spectrum for general plant damage (bischof et al. 2000). during the exposure of the macroalgae to uvr, subsamples were taken at days 1, 14 and 28. for the subsamples, entire macroalgal thalli (3–5 g fresh weight for each sample) were incubated in quartz glass flasks (volume 250–300 ml) sealed with glass stoppers and polytetrafluoroethylene (ptfe) collars. the flasks were filled with nutrient-enriched sterile seawater (provasoli enriched seawater) collected from the north sea so that no headspace remained (starr & zeikus 1993). a 4-h incubation period was chosen to allow for the release of detectable quantities of reactive organic halogens by the macroalgae used in the experiment. the incubation period was chosen to coincide with the middle of the daylight period. during the incubation period, the quartz glass flasks were gently shaken (15 rpm) to support the distribution of the reactive halogen-containing volatile organic compounds in the medium inside the glass flasks. no visible damage of the algal sample tissue was observed for the duration of the experiment. five replicates of the macroalgal species were performed in each incubation experiment. control experiments were conducted by exposing the culture medium without algae to the same conditions as the algal cultures. after termination of the experiment, the culture medium containing the reactive halogen-containing volatile organic compounds was placed in 120-ml glass bottles. the bottles were sealed with crimper caps, that is, aluminium caps with ptfe septa (chromacol, welwyn garden city, herts, uk), and stored at 4°c until they were analysed. analysis of the first replicate started immediately after termination of the incubation experiment. prior to analysis, the sample glass bottles were kept at ca. 20°c and in the dark for 30 min. one hundred millilitres of the culture medium in the sample glass bottle was analysed for volatile organohalogens by automated purge-and-trap gas chromatography and electron capture detection with liquid nitrogen for pre-concentration (cp 9000 instrument with automated purge-and-trap injector; chrompack, middelburg, the netherlands). the sample was transferred with a syringe into the purge-andtrap unit. helium was used as the purge gas at a purge flow of 40 ml min-1 and a purge time of 15 min. the compounds were separated on an rtx-volatiles column (40 m length, inner diameter 0.32 mm, film thickness 3 mm; restek, bellefonte, pa, usa). the temperature programme was set to 50°c isothermal for 10 min, a heating rate of 4°c min-1 and then 150°c isothermal for 5 min. the total run time was 40 min. identification of the compounds and calculation of the compound concentrations was carried out by adding a calibration standard of the pure compounds (p.a.) in methanol directly to 100 ml pre-purge milli-q water. the water containing the standard was then purged for 15 min, and the results for the areas were used to calculate the compound concentrations corrected for recovery. detection limits ranged from 0.02 to 0.12 pmol l-1, and recovery efficiencies ranged from 47 to 100%. randomly selected samples were analysed on a column with a different stationary phase (spb624 column, length 60 m, inner diameter 0.25 mm, film thickness 1.4 mm; supelco, bellefonte, pa, usa). comparisons of the results from the samples with results from a calibration standard run on the same column were made to increase the reliability of the identified compounds. results in the experiment, the incubation medium used was seawater, which itself contained reactive halogen-containing volatile organic compounds. the concentrations in the seawater medium were within the concentration ranges previously detected in seawater samples (table 1). the effect of uvr on these volatile organohalogens was investigated prior to the incubation experiment. except for methyl iodide, the concentrations of volatile organohalogens in the culture medium did not change significantly when exposed to uvr (table 1). the levels of emitted reactive organic halogens were calculated using the quantities of the individual volatile organohalogens released by the algae. thus, reactive organic chlorine is the molar sum of chlorine from ch2cl2, chcl3, 1,1,1ch3ccl3, ccl4, c2cl4, chbrcl2, chbr2cl and ch2cli. reactive organic bromine is the molar sum of bromine from ch2br2, chbr3, 1,2-etbr2, chbrcl2 and chbr2cl, and reactive organic iodine is the molar sum of iodine from ch2i2 and ch2cli. methyl iodide (ch3i) has not been considered in the molar sum calculations for reactive organic iodine, as significant levels were found in the incubated seawater without algal samples (see table 1). reactive organic halogens f. laturnus et al. polar research 29 2010 379–384 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd380 a significant increase in organic iodine emission was observed over the duration of exposure to elevated uvr (fig. 1; table 2). in contrast, for bromine, a significant decrease was observed during the first half of the exposure period, and a non-significant increase was observed during the second half of the exposure period (fig. 1; table 2). chlorine exhibited a significant decrease in emission after exposure to uvr, followed by a significant increase with longer durations of uvr exposure (fig. 1; table 2). compared with the emission rates for reactive iodine and bromine, however, chlorine showed sevenfold lower rates. table 1 influence of ultraviolet radiation (uvr) on reactive halogen-containing volatile organic compounds in filtered seawater used as the medium for the incubation experiment: one set of seawater samples was exposed for 4 h to photosynthetic active radiation (par), and one set was exposed for 4 h to par + uvr (a + b). concentration in oceansa compound par par + uvr p value range average min./max. average min./max. (pmol l-1) (pmol l-1) (pmol l-1) 0.05–18 ch3i 7.9 7.3/9.7 13.6 12/15.7 0.004 0.4–40 ch2cli 0.47 0.37/0.52 0.53 0.31/0.61 0.389 6.2–48 ch2i2 1.73 1.43/1.98 1.40 1.18/2.9 0.569 no data ch2cl2 223 131/407 167 138/220 0.631 9–63 chcl3 1.8 1.6/2.3 1.9 1.6/2.4 0.315 no data ch3ccl3 2.5 2.2/2.8 2.3 2.2/2.5 0.410 5.4–16 ccl4 3.1 2.3/3.4 3.0 2.5/3.3 0.416 19b c2hcl3 0.8 0.7/1.0 0.8 0.7/0.9 0.734 4.1b c2cl4 1.8 1.5/2.1 1.8 1.5/2.0 0.807 0.3–16 ch2br2 1.3 0.9/2.6 0.9 0.4/1.2 0.085 0.6–2 chbrcl2 0.1 0.1/0.2 0.2 0.1/0.3 0.789 0.1–5.1 chbr2cl 0.42 0.30/0.44 0.46 0.3/0.6 0.541 1.0b 1,2-etbr2 0.27 0.23/0.29 0.31 0.23/0.36 0.466 3–182 chbr3 4.0 3.5/5.0 4.0 2.8/5.3 0.688 the difference between treatments was tested with a mann–whitney u-test at 5% significance level (n = 5). a concentration in oceans as reviewed by laturnus (2003). b no range was given in the literature. fig. 1 emission of reactive organic halogens by the brown macroalga saccharina latissima ex. laminaria saccharina (l.) lamouroux was exposed for up to 28 days to photosynthetic active radiation (par) and ultraviolet radiation (uv-a + uv-b). results are shown as box plots for five replicates. as the data material was not normally distributed, the central tendency is given as the median, and the variation is presented as the first and third quartiles. the line inside the box represents the median values. the lower and upper edges of the box represent the first and third quartiles, respectively. minimum and maximum values are given by the error bars of the boxes. circles represent outliers (values between 1.5 and 3 box lengths from the upper/lower edge of the box). asterisks indicate extreme values (more than three box lengths from the upper/lower edge of the box.). fw, fresh weight; n = 5. reactive organic halogensf. laturnus et al. polar research 29 2010 379–384 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 381 discussion the results of this study suggest that macroalgae may become more important for regulating the occurrence of reactive organic halogens, provided that uvr levels continue to increase. the biochemical processes underlying the formation of reactive organic halogens are suggested to be based on enzymatically-induced halogenation of organic matter, involving either haloperoxidases or halogenases (geigert et al. 1984; butler & walker 1993; van pee & unversucht 2003). in general, halogenation processes and the formation of reactive organic halogens are related to the occurrence of oxidative stress caused by exposure of the algae to hydrogen peroxide or ozone (palmer et al.2005; weinberger et al. 2007). recently, it was suggested that accumulated iodide acts as an inorganic antioxidant, and constitutes an extracellular protection of macroalgae against oxidative stress (küpper et al. 2008). in our study, the algae investigated were not subjected to any uvr prior to experimentation, i.e., during cultivation. exposure to uvr may therefore have triggered additional stress in the algae, which could lead to the formation of additional reactive oxygen species, such as hydrogen peroxide (he & häder 2002; dummermuth et al. 2003). for example, in response to such oxidative stress, macroalgae generate and release higher quantities of reactive iodine, which in a second step can react with dissolved organic matter to form volatile organoiodine compounds (mcfiggans et al. 2004). data on possible emissions of inorganic bromine and chlorine are not yet available, but recently, increasing attention has been given to the emission of inorganic iodine by macroalgae (e.g., mcfiggans 2005; palmer et al. 2005; küpper et al. 2008). the authors described significantly greater levels of inorganic iodine emissions compared with organic iodine under oxidative stress caused by hydrogen peroxide or ozone. inorganic iodine emitted into the atmosphere is considered a main source for coastal particles involved in atmospheric radiation and temperature control (mcfiggans et al. 2004; mcfiggans 2005). a recent field study on the emission of inorganic iodine by laminaria digitata (hudson) lamour under elevated levels of ultraviolet radiation (uvr + par) showed a more than 14 times higher emission of inorganic iodine, compared with emission under exposure to par alone (grose, laturnus & wiencke, unpubl. ms.). the study further revealed a sevenfold lower emission of organic iodine compared with iodide, whereas under exposure to par, organic iodine is the dominant species. thus, exposure of macroalgae to uvr may not only affect the emission of volatile organoiodines but additionally may lead to an increased release of inorganic iodine. macroalgae of the order laminariales and the genus saccharina are usually submerged, and are only exposed to the atmosphere during spring tides. a sudden exposure of the macroalgae to uvr would probably lead to a burst of inorganic iodine into the atmosphere. in contrast, macroalgae occurring in the eulitoral are regularly exposed to uvr, and are probably less affected by uvr regarding the emission of iodide. however, data on a wider range of different macroalgae species are still scarce, and more comprehensive evaluations of the atmospheric contribution of inorganic iodine emissions by macroalgae still need to be performed. during the incubation, and after the experiment was terminated, the algal samples also showed no visible tissue damage, such as colour change or thallus bleaching. however, no specific physiological measurements were made in this regard, so it is not possible here to estimate the stress induced during exposure to uvr. macroalgae growing directly in the natural habitat may be better adapted to elevated levels of uvr, so their regulation of reactive organic halogens may be enhanced less by uvr than this study suggests. despite a worldwide ban on chlorineand brominecontaining compounds after the discovery of the ozone hole over antarctica, it remains uncertain when the stratospheric ozone layer will completely recover. although some studies have reported that regulatory action to reduce the atmospheric input of chlorineand bromine-containing compounds has already begun to be effective (pyne 2003; tabazadeh & cordero 2004), others have suggested that unknown mechanisms may still be responsible for the loss of stratospheric ozone (schiermeier 2007). thus, leaning back and announcing that the ozone problem has now been solved may not be a wise decision at present. additional threats, such as the table 2. significant levels for the lease of total halogen by macroalgae exposed to photosynthetic active radiation (par) and par + ultraviolet radiation (uvr; uv-a + uv-b), as tested by the mann–whitney u-test at 5% significance level (n = 5) mann–whitney u-test reactive organic chlorine reactive organic bromine reactive organic iodine par vs. 1 day uvr p = 0.009 p = 0.754 p = 0.009 1 day vs. 14 days uvr p = 0.465 p = 0.047 p = 0.175 14 days vs. 28 days uvr p = 0.917 p = 0.175 p = 0.009 the release rates are presented in fig. 1. reactive organic halogens f. laturnus et al. polar research 29 2010 379–384 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd382 emission of ozone-depleting compounds through uncontrolled and large-scale biomass burning (manö & andreae 1994; yvon-lewis et al. 2008) and illegal production (spurgeon 1997) may impede the recovery of the stratospheric ozone layer. furthermore, greenhouse gases simultaneously cause warming of the troposphere and radiative cooling of the stratosphere (foster & shine 1999). lower stratospheric temperatures promote the formation of polar stratospheric clouds, and support the destruction of stratospheric ozone. consequently, the levels of uvr reaching the biosphere may still increase in the future, as already intimated earlier (austin et al. 1992; shindell et al. 1998). elevated levels of uvr may increase the environmental input of some reactive organic halogens from marine macroalgae, and perhaps other natural sources known to emit reactive organic halogens. when these halogens are transferred into the atmosphere, they are likely to cause further destruction of stratospheric ozone. thus, the present picture of the recovery of stratospheric ozone might be even more complex than is widely assumed. caution might be recommended before giving the ozone layer a clean bill of health and announcing that the threat of stratospheric ozone destruction has been solved. acknowledgements the authors are indebted to o. schrems, alfred wegener institute for polar and marine research, for granting the use of the purge-and-trap gas chromatographic system, and to c. daniel for maintaining the macroalgae cultures. fl, who was at the department of thematic studies— water and environmental studies, linköping university, at the time the research reported here was carried out, thankfully acknowledges a fellowship from the hanse institute for advanced studies, a scholarship from linköping university and finacial support from the alfred wegener institute to conduct the study presented in this paper. ts acknowledges support by grants from the swedish research council and the swedish research council for environment, agriculture and spatial planning. the authors acknowledge the contribution of two anonymous reviewers whose comments helped to improve the manuscript. references austin j., butchart n. & shine k.p. 1992. possibility of an arctic ozone hole in a doubled-co2 climate. nature 360, 221–225. bischof k., hanelt d., tüg h., karsten u., brouwer p.e.m & wiencke c. 1998. acclimation of brown algal photosynthesis to ultraviolet radiation in arctic coastal waters (spitsbergen, norway). polar biology 20, 388–395. bischof k., hanelt d. & wiencke c. 2000. effects of ultraviolet radiation on photosynthesis and related enzyme reactions of marine macroalgae. planta 211, 555–562. butler a. & walker j.v. 1993. marine haloperoxidases. chemical reviews 93, 1937–1944. carpenter l.j. & liss p.s. 2000. on temperate sources of bromoform and other reactive organic bromine gases. journal of geophysical research—atmospheres 105, 20 539–20 547. daniel j.s., solomon s., portmann r.w. & garcia r.r. 1999. stratospheric ozone destruction: the importance of bromine relative to chlorine. journal of geophysical research—atmospheres 104, 23 871–23 880. dummermuth a.l., karsten u., fisch k.m., koenig g.m. & wiencke c. 2003. responses of marine macroalgae to hydrogen peroxide stress. journal of experimental marine biology and ecology 4114, 1–19. foster p.m.f. & shine k.p. 1999. stratospheric water vapour changes as a possible contributor to observed stratospheric cooling. geophysical research letters 26, 3309–3312. franklin l.a. & forster r.m. 1997. the changing irradiance environment: consequences for marine macrophyte physiology, productivity and ecology. european journal of phycology 32, 207–232. geigert j., neidleman s.l., dewitt s.k. & dalietos d.j. 1984. halonium ion-induced biosynthesis of chlorinated marine metabolites. phytochemistry 23, 287–290. he y.y. & häder d.p.j. 2002. uv-b induced formation of reactive oxygen species and oxidative damage of the cyanobacterium anabaena sp.: protective effects of ascorbic acid and n-acetyl-l-cysteine. photochemistry and photobiology 66, 115–124. küpper f.c., carpenter l.j., mcfiggans g.b., palmer c.j., waite t.j., boneberg e.-m., woitsch s., weiller m., abela r., grolimund d., potin p., butler a., luther g.w. iii, kroneck p.m.h., meyer-klaucke w. & feiters m.c. 2008. iodide accumulation provides kelp with an inorganic antioxidant impacting atmospheric chemistry. proceedings of the national academy of sciences 105, 6954–6958. laturnus f. 2001. marine macroalgae in polar regions as natural sources for volatile organohalogens. environmental science and pollution research 8, 103–108. laturnus f. 2003. natural sources of volatile organohalogens—impact on the biosphere. phd thesis, university of copenhagen. laturnus f., svensson t., wiencke c. & oeberg g. 2004. ultraviolet radiation affects emission of ozone-depleting substances by marine macroalgae—results from a laboratory incubation study. environmental science technology 38, 6605–6609. lüning k. 1990. seaweeds—their environment, biography and ecophysiology. new york: john wiley & sons. manö s. & andreae m.o. 1994. emission of methyl bromide from biomass burning. science 263, 1255–1256. reactive organic halogensf. laturnus et al. polar research 29 2010 379–384 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 383 mcfiggans g. 2005. marine aerosols and iodine emissions. nature 433, e13. mcfiggans g., coe h., burgess r., allan j., cubison m., alfarra m.r., saunders r., saiz-lopez a., plane j.m.c., wevill d., carpenter l.j., rickard a.r. & monks p.s. 2004. direct evidence for coastal iodine particles from laminaria macroalgae—linkage to emissions of molecular iodine. atmospheric chemistry and physics 4, 701–713. palmer c.j., anders t.l., carpenter l.j., küpper f.c. & mcfiggans g.b. 2005. iodine and halocarbon response of laminaria digitata to oxidative stress and links to atmospheric new particle production. environmental chemistry 2, 282–290. pedersén m., collén j., abrahamsson k. & ekdahl a. 1996. production of halocarbons from seaweeds: an oxidative stress reaction? scientia marina 60, 257–263. pyne s. 2003. ozone killer tamed. science now 818, 2. schiermeier q. 2007. chemists poke hole in ozone theory. nature 449, 382–383. shindell d.t., rind d. & lonergan p. 1998. increased polar stratospheric ozone losses and delayed eventual recovery owing to increasing greenhouse-gas concentrations. nature 392, 589–592. solomon s. 1999. stratospheric ozone depletion: a review of concepts and history. reviews of geophysics 37, 275–316. spurgeon d. 1997. ozone treaty must tackle cfc smuggling. nature 389, 219. starr r.c. & zeikus j.a. 1993. utex—the culture collection of algae at the university of texas at austin. journal of phycology 29, 1–106. tabazadeh a. & cordero e.c. 2004. new directions: stratospheric ozone recovery in a changing atmosphere. atmospheric chemistry 38, 647–649. weinberger f., coquempot b., forner s., morin p., kloareg b. & potin p. 2007. different regulation of haloperoxidation during agar oligosaccharide-activated defence mechanisms in two related red algae, gracilaria sp. and gracilaria chilensis. journal of experimental botany 58, 4365–4372. van pee k.h. & unversucht s. 2003. biological dehalogenation and halogenation reactions. chemosphere 52, 299–312. yvon-lewis s.a., saltzman e.s. & montzka s.a. 2008. recent trends in atmospheric methyl bromide: analysis of post-montreal protocol variability. atmospheric chemistry and physics 9, 5963–5974. reactive organic halogens f. laturnus et al. polar research 29 2010 379–384 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd384 no job name isostatic stability of the east antarctic station dumont d’urville from long-term geodetic observations and geophysical models martine amalvict,1 pascal willis,2,3 guy wöppelmann,4 erik r. ivins,5 marie-noëlle bouin,6 laurent testut7 & jacques hinderer1 1 institut de physique du globe de strasbourg (umr 7516 cnrs-ulp), 5 rue rené descartes, 67000 strasbourg, france 2 institut géographique national, direction technique, 2 avenue pasteur, bp 68, 94160 saint-mandé, france 3 institut de physique du globe de paris, géophysique spatiale et planétaire, 35 rue hélène brion, 75013 paris, france 4 centre littoral de géophysique, université de la rochelle, avenue michel crépeau, 17042 la rochelle cedex 1, france 5 jet propulsion laboratory, california institute of technology, pasadena, ca 91109, usa 6 institut géographique national, lareg, 6 et 8 avenue blaise pascal, 77455 marne-la-vallée cedex, france 7 legos-umr5566-cnrs/cnes/ups/ird-14 avenue edouard belin, 31400 toulouse, francepor_091 193..202 abstract geodetic measurements of the vertical crustal displacement collocated with absolute gravity changes provide a discriminatory measurement of present-day glacial changes, versus more deeply seated rock motions caused by glacial isostatic adjustment (gia). at the east antarctic station of dumont d’urville, we compare the displacements derived from continuous doris (1993.0– 2006.0) and global positioning system (gps) (1999.0–2005.7) data, and observed changes in absolute gravity (2000–2006), with the predicted vertical displacement and change in gravity from gia modelling. the geodetic results have mutual self-consistency, suggest station stability and provide upper bounds on both gia and secular ice mass changes. the gia models tend to predict amplitudes of rock motion larger than those observed, and we conclude that this part of antarctica is probably experiencing a slight gain in ice mass, in contrast to west antarctica. keywords absolute gravity; antarctica; doris; dumont d’urville; gps; tide gauge. correspondence pascal willis, institut de physique du globe de paris, géophysique spatiale et planétaire, 35 rue hélène brion, 75013 paris, france. e-mail: willis@ipgp.jussieu.fr doi:10.1111/j.1751-8369.2008.00091.x the mass change of the antarctic ice sheet plays a key role in mean sea-level variation (nerem et al. 2006), but estimates of antarctic mass balance are still controversial (e.g., rignot & thomas 2002). the ice mass budget results from the combination of accumulation (precipitation) and ablation (calving, ice shelf collapse and basal melting). recent studies (chen et al. 2006; ramilien et al. 2006; velicogna & wahr 2006; rignot et al. 2008) suggest the possibility of a recent (2002–06) acceleration of antarctic mass loss. however, such a loss is primarily in the west antarctic ice sheet. grace results especially suggest that mass of the east antarctic ice sheet (eais) is either close to equilibrium (velicogna & wahr 2006) or slightly increasing (ramilien et al. 2006). a mass increase is also seen in radar altimetry (davis et al. 2005; zwally et al. 2005), and mass balance considerations mainly based on remote sensing (rignot & thomas 2002; remy & frezzotti 2006) suggest that eais is close to equilibrium. similar to the vertical motion of the crust, the ice surface height variation may also be associated with either glacial isostatic adjustment (gia) or present-day ice mass (pdim) variability. wahr et al. (1995) noted that a comparison of observations using absolute gravity (ag) and satellite geodetic techniques offers one method of separating the two different signals. antarctic ag measurements began in 1990, and have been taken on a regular basis since then (e.g., mäkinen et al. 2007). although ag measurements are available at 12 stations, repeated observations are only available at five stations: terra nova bay, mcmurdo, syowa, abao and dumont d’urville, all located in the eastern part of the antarctic continent. like most of the ag stations, dumont d’urville (ddu) has long been collocated with satellite geodesy measurements (gps and doris) (fig. 1). using these collocated observations, we aim to assess whether this area of east antarctica is stable, and to determine which part of the vertical motion observed is related to gia or pdim changes. we focus on this station for two main reasons: (1) this is the only opportunity in this part of antarctica to conjointly use ag measurements and polar research 28 2009 193–202 © 2009 the authors 193 mailto:willis@ipgp.jussieu.fr fig. 1 (a) the geographical location of dumont d’urville station in antarctica (reproduced with permission of the french polar institute), and (b) the location of geodetic instruments, based on information from the institut géographique national/service d’installation et de maintenance des balises (see fagard 2006). long-term geodetic observations in east antarctica m. amalvict et al. polar research 28 2009 193–202 © 2009 the authors194 multi-technique space geodesy positioning, and (2) as this part of east antarctica is supposed to be stable, ddu behaviour should be representative of the surrounding area. in restricting our focus on ddu, we do not aim to constrain the antarctic intraplate stability, nor the horizontal glacial deformation. the ddu station (66.67°s, 140.17°e) was established in 1950 on petrel island in the terre adélie sector, east antarctica (fig. 1a). since that time geodetic operations have been regularly carried out during the yearly occupation of the station, or during summer campaigns (in 1995 and 1996). twenty years ago, a new era began with the introduction of satellite geodesy and global navigation satellite systems (gnss) precise positioning (figs. 1b, 2). figure 1b shows the location of the different geodetic instruments, while fig. 2 presents the data availability per technique. in this paper, we first present results from geodetic observations at ddu: doris since 1993, gps since 1997, and surface ag observations from 2000 and 2006. we validate our 3d doris and gps velocities by comparing them with recent geodetic or geophysical plate motion models, and then investigate the gia and present-day effects using both measurements and ij05 gia model predictions (ivins & james 2005). gps data early gps observations were performed at ddu in 1995, from january 30 to february 8, and in 1996, from january 20 to february 10, by the institut géographique national (ign), within the scientific committee on antarctic research (scar) campaigns. a permanent gps station was installed at ddu in december 1997 (bouin & vigny 2000). this gps site (dum1) is now part of the international gnss service (igs) network (dow et al. 2005), and fortunately the antenna was set up on the same pillar as that used during the campaign measurements. dum1 has been continuously operating for 10 years, and contributes to the igs pilot project tiga that aims to monitor the stability of the land upon which the tide gauges are settled (wöppelmann et al. 2007; wöppelmann et al. 2008). a dedicated analysis centre was set up at the university of la rochelle, which analyses the gps data from dum1, along with 223 other stations, on a routine basis. this gps processing is performed using gamit software (king & bock 2005) on a free network approach and with a stateof-the-art strategy, which is described extensively by wöppelmann et al. (2007) and wöppelmann et al. (2008). absolute receiver phase centre corrections, satellite antennae modelling and the global mapping function (gmf) troposphere mapping function from boehm, niell et al. (2006) are used in the processing scheme. vienna mapping functions 1 (vmf1; boehm, werl et al. 2006) are known to more accurately model tropospheric seasonal variations, especially in antarctica. nevertheless, the vmf grids were not available at the time this processing began, and were therefore not used in this work. a particular concern in the gps data processing was to ensure the most rigorous possible consistency in the models and corrections that were applied over the whole data span. no atmospheric loading modelling was used, as the current model (tregoning & van dam 2005) is too imprecise to include subdiurnal effects (ray, pers. comm.). the weekly gps solutions are combined using catref software, and are aligned to itrf2000 using the minimal constraints approach described by altamimi et al. (2002). the reprocessing of ddu observations has been performed backwards for gps data spanning the period 1999.0– 2005.7 (a time span of 6.7 years). possible seasonal effects caused by atmospheric loading or unmodelled tropospheric variations do not influence our velocities, as this observation period greatly exceeds the minimum limits set by blewitt & lavallée (2002). results for dum1 are presented in table 1 and fig. 3. the observed linear trends for horizontal north and east components are, respectively: -11.11 � 0.08 mm yr-1 and 7.98 � 0.07 mm yr-1. these gpsderived velocities are consistent with the previous results obtained using gps (-13 � 3 mm yr-1 and 15 � 10 mm yr-1; bouin & vigny 2000) or a multitechnique combination (-8.1 � 1.0 mm yr-1 and 11.6 � 0.8 mm yr-1; altamimi et al., 2002). our vertical rate is 0.34 � 0.12 mm yr-1. in a previous study, mäkinen et al. (2007) provided two different values without giving any formal errors for the vertical trends (-0.56 mm yr-1 and +0.43 mm yr-1). here, we claim that our results, which are consistent with the second value, are more accurate fig. 2 geodetic data available at dumont d’urville station. the data used in this study are in the darker shade. long-term geodetic observations in east antarcticam. amalvict et al. polar research 28 2009 193–202 © 2009 the authors 195 than the earlier determinations for two main reasons: (1) we used a state-of-the-art processing strategy, including new models and a validated reference frame realization, and (2) our gps processing strategy is consistent throughout the whole time series, which was not the case in the previous studies. for the same reason, our time series behaviour has been shown to be extremely close to a pure white-noise process (feissel-vernier et al. 2007), without any flicker noise. this makes us quite confident of the uncertainties associated with our results. the consistency with previous results (bouin & vigny 2000; altamimi et al. 2002) simply demonstrates the robustness of our results. doris data the doris (doppler orbitography and radiopositioning integrated by satellite) station in terre adélie has been almost continuously observing since the introduction of the system. the doris station in terre adélie (tavernier et al. 2006) was installed on 5 february 1987 (adea, alcatel antenna), and was later upgraded on 1 march 2002 (adeb, starec antenna). the 1993.0–2006.0 data were processed on a daily basis using the gipsy/oasis ii software and a free-network approach, and were then combined at the normal matrix level into weekly freenetwork solutions (willis et al. 2005). a cumulative table 1 observations and modelling of changes in gravity, and in horizontal and vertical displacements, at dumont d’urville station, east antarctica. aga dorisa gpsa gia modela plate motionb du/dt mm yr-1 — 0.29 � 0.13 0.34 � 0.12 2.49 0 north component mm yr-1 — -10.09 � 0.16 -11.11 � 0.08 — -13< <-11 east component mm yr-1 — 10.85 � 0.21 7.98 � 0.07 — 7< <9 d(dg)/dt mgal yr-1 -0.22 � 0.38 — — -0.37 — athis study. bderived from information available at the unavco website: http://sps.unavco.org/crustal_motion/dxdt/model. fig. 3 doris (adea and adeb) and gps (dum–1) position residual time series in mm: (a) vertical, (b) north horizontal and (c) east horizontal components. long-term geodetic observations in east antarctica m. amalvict et al. polar research 28 2009 193–202 © 2009 the authors196 http://sps.unavco.org/crustal_motion/dxdt/model solution (position/velocity) was derived using information on station discontinuity from willis & ries 2005). this solution was then projected and transformed (using a 14-conformal transformation) into itrf2000 and itrf2005p (altamimi et al. 2007). as a result of the nearly polar orbit of the spot satellites, the high-latitude doris stations provide a richer source of data, from which we achieve results of higher accuracy. on the other hand, the station vertical component, highly correlated with the z-axis, is potentially affected by systematic errors (willis et al. 2006). it must be noted that the results from doris are usually as accurate in the horizontal component as in the vertical component. in particular, in order to avoid correlation between the doris vertical results and the tropospheric correction, a specific time constraint is used in the gipsy/ oasis ii estimation between consecutive passes of any satellites (see snajdrova et al. [2006] for a description of the technique, as well as for comparisons of the tropospheric delay with very long baseline interferometry [vlbi], gps and water vapour radiometry [wvr] results). doris results are given in table 1 and fig. 3. the observed linear trends for vertical, and horizontal north and east components are, respectively, 0.29 � 0.13 mm yr-1, -10.09 � 0.16 mm yr-1 and 10.85 � 0.21 mm yr-1. the precision provided in these results is the formal error after reweighting using the c2/dof value of the combination (adding the doris weekly matrices over the full period). in our opinion, these precisions are more realistic that the initial formal errors (without any c2 reweighting), and are typically smaller by a factor of 2. ag data in the framework of a project supported by the french polar institute (ipev), and dedicated to ag measurements in sub-antarctic and antarctic french scientific stations, ag was measured twice at ddu. absolute gravimeter fg5-206, of the strasbourg gravimetric observatory, was set up in a shelter established on the bedrock, and measurements were obtained from 26 february to 2 march 2000, and on 5–8 february 2006. the 2000 experiment (11 800 drops in 118 h) is described in amalvict et al. (2001) and hinderer et al. (2002). the 2006 experiment (16 187 drops in 82 h of continuous measurement) is described in amalvict et al. (2007). we processed the raw data using micro-g solutions “g” v6.06 software, and reduced the observations in a similar way for the two campaigns, using the same vertical gradient of gravity, and the same models for the solid earth tides, ocean tides, motion of the pole of rotation (using the published x and y components from the international earth rotation and reference systems service [iers] bulletin b) and atmospheric pressure effects using the standard nominal pressure (see mäkinen et al. 2007). the respective values of gravity are g2000 = 982 387 168.34 � 1.68 mgal and g2006 = 982 387 167.02 � 1.54 mgal (1 mgal = 10-8 ms-2). the corresponding gravity variation over 6 years (2000–2006) is -0.2 � 0.4 mgal yr-1 (table 1), i.e., a nonsignificant small decrease in gravity. the error on this trend takes into account the 2000 and 2006 experimental standard deviations of the mean (s/n, where s is the set scatter and n is the total number of sets), the set-up noise (1 mgal), and the system (instrument type) noise (1.1 mgal), these last two quantities being defined for fg5 by micro-g solutions. modelling the ij2005 (ivins & james 2005) model (uplift shown in fig. 4a; 2.49 mm yr-1 in ddu) assumes a simple threelayer mantle structure, tailored to the optimum global viscosity model (mf) of mitrovica & forte (2004). the glacial history assumes continuous drawdown of ice heights since 3.2 kya and that all change has ceased at the time of evaluation, so that the uplift is computed purely on the basis of past glacial changes. the model is radially stratified, self-gravitating, and only the ocean load associated with antarctic glaciation and deglaciation is included. the effects of accounting for the total ocean loading are not negligible, but are quite small in comparison with direct loading effects, such as the last 2 ky of glacial history, as discussed by ivins & james (2005). the model includes enhanced precipitation on the east antarctic coast after the antarctic cold reversal, and during holocene times. this is clearly found in the analyses of ice core record data (wolff et al. 2006), and is supported by global circulation model simulations of the last glacial maximum climate (toracinta et al. 2004). we minimally account for an early holocene glacial expansion into prydz bay (domack et al. 1991); however, we lack information on the ice extent and mass involved. figure 4b shows the predicted present-day secular rate of change for surface gravity (-0.37 mgal yr-1 in ddu). the ice model in this region of antarctica is quite uncertain. no ab initio effort was made to adjust the load, nor the mantle viscosity parameters, as the main point here is to demonstrate that these geodetic observations hold promise for providing significant tests of such model predictions. results and discussion our horizontal and vertical velocities obtained from doris and gps data are in mutual agreement (see fig. 3 long-term geodetic observations in east antarcticam. amalvict et al. polar research 28 2009 193–202 © 2009 the authors 197 and table 1). the common time span extends from 1999 to 2005, providing almost 7 years of continuous observations. to validate these results with external comparison, we checked the horizontal velocities obtained at ddu from various geodetic or geophysical tectonic models. the values for the north and east components provided at http://sps.unavco.org/crustal_motion/dxdt/model are highly consistent with our results (table 1), with -12.05 mm yr-1 and 8.15 mm yr-1, respectively, from itrf2000 (altamimi et al. 2002), -13.07 mm yr-1 and 9.35 mm yr-1, respectively, from revel 2000 (sella et al. 2002), and -11.64 mm yr-1 and 7.47 mm yr-1, respectively, from gsrm v1.2 (kreemer et al. 2003). this agreement confirms the accuracy of our space geodetic results. we analysed the doris and gps time series to detect seasonal variations (table 2). the gps time series show annual signals of 1–2 mm in the horizontal components, and 5 mm in the vertical. no vertical annual signal is observed in the doris results. we are now attempting to link these variations with the seasonal ice mass fluctuations observed from recent satellite missions. results from grace (llubes et al. 2007), combined with lageos data for the degrees 1 and 2 of the gravity field, and with data from ers1 and ers2 satellite altimetry (wingham et al. 2006), showed seasonal variations over the whole continent. although these two studies considered different time spans (1992–2003, wingham et al. 2006; 2002– 2005, llubes et al. 2007), they agree globally with each other in assessing the seasonal elevation change over the whole continent. the ers data (wingham et al. 2006) reveal a global annual elevation change of 50 mm, whereas the grace observations (llubes et al. 2007) lead to seasonal variations of 15 mm water equivalent. both studies claim to be representative of the whole continent, with coverage of 85 or 100%, respectively, of the total area. these variations agree well with the in-phase annual signal we observe on the gps vertical component (with the maximum loading effect observed in may or june). nevertheless, a simple loading computation shows that the amplitude is too small to explain the gps vertical signal. as the total area of the antarctic ice sheet is 11.7 ¥ 106 km2, we can roughly model it as a disc of table 2 seasonal signatures of gps and doris signals: periodicities and amplitudes. doris gps vertical 118 days 1.023 yr 5.68 mm 5.04 mm north component 1.002 yr/118 days 1.013 yr 12.17 mm/8.67 mm 1.32 mm east component 118 days 3.333 yr/1.013 yr 12.53 mm 1.46 mm/1.32 mm fig. 4 prediction maps of (a) vertical displacement and (b) change of gravity from the ij05 model. long-term geodetic observations in east antarctica m. amalvict et al. polar research 28 2009 193–202 © 2009 the authors198 http://sps.unavco.org/crustal_motion/dxdt/model radius 1930 km. a global ice thickness variation of 50 mm over this entire area will result in a 2.5–3 mm annual signal in ddu, whereas a change of 15 mm water equivalent over the same area will lead to 0.7–1 mm at most, far below the observed amplitude. our ag measurement results from ddu are in fair agreement with the gps and doris vertical velocities, indicating little change in pdim and quite small vertical displacement, resulting from the combined influence of gia and elastic rebound. as clearly reflected in the standard deviations, continuous geodetic observations from space provide more precise information about gia effects than episodic ag measurements, which are more sensitive to one single measurement. previous studies came to the same conclusion (larson & van dam 2000; lambert et al. 2006). a simple combined analysis of these data can be achieved if we assume that the ag data are free from local effects, such as snow-fall anomalies or unknown melt–freeze events in nearby subglacial lakes, and so on. this is the case of the ddu station, where no snowfall anomaly was observed during either of the two campaigns. the relationships developed by wahr et al. (1995) apply if we further assume that all mass changes, including those of cryospheric origin, occur at a spherical surface, with radius r = ã, below the ag position on the spherical surface, at r = ã + dã, with dã � 0. these relationships provide a simple technique for distinguishing pdim changes from gia, and are quite analogous to the combination of geodetic data for ice mass and crustal motion in svalbard discussed recently by sato et al. (2006). we assume that the observed vertical displacement du/dt is the sum of the elastic pdim term due/dt and the viscous gia term duv/dt. similarly, the total gravity change d(dg)/dt is the result of pdim-related variation d(dge)/dt and gia effects d(dgv)/dt. the total du/dt displacement that we measured (0.34 � 0.12 mm yr-1 from gps and 0.29 � 0.13 mm yr-1 from doris) is significantly different from the gia uplift modelled in the ij05 model (2.49 mm yr-1), displayed in table 3. if we accept the ij05 prediction of the ground motion resulting from gia as a reasonable a priori estimate, the stability we observe should result from two almost opposite vertical variations: duv/dt = 2.49 mm yr-1 and due/dt = -2.2 mm yr-1. we hypothesize that the contribution to the change in gravity caused by variability in pdim, d(dge)/dt, mainly results from the free-air gravity contribution due/dt (a small redistribution of solid earth mass and a small variation caused by the change in ice mass, as the site we measure is not situated on the ice). providing the ice changes are widespread, and not concentrated at the ag site, the conversion factor for the ice elastic loading is about -0.27 mgal mm-1 (james & ivins 1998; sato et al. 2006), leading to the conclusion that there is a positive ice elasticity induced gravity change d(dge)/dt of +0.59 mgal yr-1. the viscous gravity change contribution d(dgv)/dt, on the other hand, cannot be obtained in the same way, as gia crustal motion is driven by a redistribution of mass within the earth. the gia term itself is the addition of d m vδg( ), resulting from the change in the mass distribution of ice and solid earth (referred to as the gravity anomaly), and of d u vδg( ), resulting from the vertical displacement duv/dt (referred to as the free-air gravity contribution). we use the proportionality constant empirically determined by wahr et al. (1995), for a wide range of viscosity profiles (see also james & ivins 1998), of -0.15 mgal mm-1 to derive a value of -0.37 mgal yr-1 for d(dgv)/dt from the modelled value of duv/dt. the present-day value of d(dg)/dt is therefore the sum of the viscous and elastic terms: -0.37 + 0.59 = +0.22 mgal yr-1. note that this stability in gravity is fully compatible with the lack of significant change observed over 6 years of ag measurements in ddu (-0.2 � 0.4 mgal yr-1). these observations lead to the present-day stability of this part of the eais. wingham et al. (2006), using ers-1 and ers-2 data to determine the rate of elevation change of individual ice drainage basins, came to the same conclusion. they obtained a 5 � 2 mm yr-1 elevation rate in the 0.74 ¥ 106 km2 basin enclosing ddu. this corresponds to a vertical ground motion du/dt of 0.08 mm yr-1. if we now consider a wider area, as far as 1000 km away from ddu, which corresponds to the ddu and the surrounding basins, we obtain a mean ice elevation change of 0.8 mm yr-1 over a 3.1 ¥ 106 km2 area. the resulting vertical motion is less than 0.02 mm yr-1. our conclusions are also in accord with the recent results derived by rignot et al. (2008) for the region, wherein the total accumulation was nearly balanced by the ice outflux (with a slight gain of 1 � 19 gigatonnes per yr) averaged over 3.3 ¥ 107 km2 in the drainage system upstream from ddu during 1996–2006. this gain corresponds to a regional average ice elevation change of about +0.04 � 0.65 mm yr-1. table 3 vertical velocities and time gravity derivatives at dumont d’urville station, east antarctica. du/dt = 0.34 � 0.12 mm yr-1 gps measurements duv/dt = 2.49 mm yr-1 gia modelling due/dt = -2.2 mm yr-1 du/dt duv/dt d(dge)/dt = 0.59 mm yr-1 due/dt * cea d(dgv)/dt = -0.37 mm yr-1 duv/dt * cvb d(dg)/dt = 0.22 mm yr-1 d(dge)/dt + d(dgv)/dt d(dg)/dt = -0.2 � 0.4 mgal yr-1 ag measurements ace is the conversion factor for elastic loading (-0.27 mgal yr-1). bcv is the proportionality constant for viscous loading (-0.15 mgal yr-1). long-term geodetic observations in east antarcticam. amalvict et al. polar research 28 2009 193–202 © 2009 the authors 199 finally, we investigated the circum-antarctic sea level variability to look for some consistency with these conclusions concerning ice mass stability, or the slight gain over the period of observation. unfortunately, no conclusion can be drawn from the pressure tide gauge that was installed in ddu in 1997, because of gaps in the time series. other southern ocean instruments indicate coherent rates of sea level rise: testut et al. (2006) observed 1.1 � 0.7 mm yr-1 at the kerguelen islands; hunter et al. (2003) measured 0.8 � 0.2 mm yr-1 at port arthur (tasmania); and woodworth et al. (2005) reported 0.7 � 0.25 mm yr-1 at port stanley (falkland islands). these rates are likely to result from the combined global volume increase, and from the inherent dynamic nature of the antarctic circumpolar current (white et al. 1998), and are probably unrelated to direct gravitational effects of ice mass variability or to gia. this study assessed the isostatic stability of the eais area surrounding ddu. to draw wider conclusions about the behaviour of the eais, these results should be compared with other east antarctic station gnss vertical velocity and absolute gravity measurements. unfortunately, the density of human bases on this part of east antarctica remains poor. the nearest station (casey, australia) is more than 1300 km away, and is only equipped with a gps antenna. the japanese syowa station employs a combination of techniques: gps, doris, vlbi, ag and superconducting gravimeter (sg) measurements (fukuzaki et al. 2005; ohzono et al. 2006), but implementation of the ag data remains a work in progress. the focus of our results is limited to the ddu area (up to 1000 km inland and along the coast). conclusion the combination of vertical data from independent geodetic techniques—doris and gps—and absolute gravity in ddu, antarctica, shows very good agreement between the three data sets, pointing to a consistency and resolution within each technique equivalent to ca. 0.5 mm yr-1 or better. from our comparison of the measurements from both ag and vertical displacements (gps and doris) with gia models in ddu, we conclude that this part of eais is stable, or that it is possibly experiencing a small increase in ice mass. the observed vertical displacement is 0.3 � 0.13 mm yr-1, which, using the predicted value for the gia contribution, leads to an elastic contribution of -2.2 mm yr-1. this is not inconsistent with recent studies, employing the grace, altimetry and flux methods, regarding the near balanced state of the present-day eais (rignot & thomas 2002; davis et al. 2005; ramilien et al. 2006; remy & frezzotti 2006; velicogna & wahr 2006; wingham et al. 2006; rignot et al. 2008). we conclude that permanent gnss instruments provide precise information about the gia and pdim effects. conjoining the displacement measurements with gia modelling, we can estimate a predicted small ag variation in ddu ca. +0.22 mgal yr-1. this is statistically indistinguishable from our weakly constrained observation over a period of 6 years, showing a possible small trend of -0.2 � 0.4 mgal yr-1. it is clear that this constraint should improve in the future when more ag measurements become available. acknowledgements part of this research was carried out at the jet propulsion laboratory, california institute of technology, under a contract with nasa, and support for eri was provided by the earth surface and interior focus area of nasa’s earth science directorate. the financial and logistical support of the institut paul-emile victor made possible the installation and maintenance of the gps station dum1, as well as the data transfer and the ag measurement campaigns. the authors are indebted to the terres australes et antarctiques françaises for their logistical support. this paper is institut de physique du globe de paris (ipgp) contribution number 2329. references altamimi z., collilieux x., legrand j., garayt b. & boucher c. 2007. itrf2005: a new release of the international terrestrial reference frame based on time series of station positions and earth orientation parameters. journal of geophysical research—solid earth 112, b09401, doi: 10.1029/ 2007jb004949. altamimi z., sillard p. & boucher c. 2002. itrf2000: a new release of the international terrestrial reference frame for earth science applications. journal of geophysical research—solid earth 107, 2214, doi: 10.1029/ 2001jb000561. amalvict m., hinderer j. & luck b. 2001. first absolute gravity measurements at the french station dumont d’urville (antarctica). in m. sideris (ed.): gravity, geoid and geodynamics 2000. ggg2000 iag international symposium, banf, alberta, canada, july 31–august 4, 2000. pp. 373–377. heidelberg: springer. amalvict m., rogister y., hinderer j., luck b., mcqueen h. & luton g. 2007. absolute gravity measurements in terre adélie (antarctica) and at canberra (australia). gravity field of the earth. proceedings of the first international symposium of the international gravity field service. harita dergisi special issue 18, 409–413. blewitt g. & lavallée d. 2002. effect of annual signals on geodetic velocity. journal of geophysical research—solid earth 107, 2156, doi: 10.1029/2001jb000570. long-term geodetic observations in east antarctica m. amalvict et al. polar research 28 2009 193–202 © 2009 the authors200 boehm j., niell a., tregoning p. & schuh h. 2006. global mapping function (gmf): a new empirical mapping function based on numerical weather model data. geophysical research letters 33, l07304, doi: 10.1029/ 2005gl025546. boehm j., werl b. & schuh h. 2006. troposphere mapping functions for gps and very long baseline interferometry from european centre for medium-range weather forecasts operational analysis data. journal of geophysical research—solid earth 111, b02406, doi: 10.1029/ 2005jb003629. bouin m.n. & vigny c. 2000. new constraints on antarctic plate motion and deformation from gps data. journal of geophysical research—solid earth 105, 28279–2893. chen j.l., wilson c.r., blankenship d.d. & tapley b.d. 2006. antarctic mass change rates from grace. geophysical research letters 33, l11502, doi: 10.1029/ 2006gl026369. davis c.h., li y.h., mcconnel j.r., frey m.m. & hanna e. 2005. snowfall-driven growth in east antarctic ice sheet mitigates recent sea-level rise, science 308, 1898–1901. domack e.w., jull a.t. & nakao s. 1991. advance of east antarctic outlet glaciers during the hypsithermal: implications for the volume state of the antarctic ice sheet under global warming. geology 19, 1059–1062. dow j.m., neilan r.e. & gendt g. 2005. the international gps service: celebrating the 10th anniversary and looking to the next decade. advances in space research 36, 320–326. fagard h. 2006. twenty years of evolution for the doris permanent network: from its initial deployment to its renovation. journal of geodesy 80, 429–456. feissel-vernier m., de viron o. & le bail k. 2007. stability of vlbi, slr, doris and gps positioning. earth planets and space 59, 475–497. fukuzaki y., shibuya k., doi k., ozawa t., nothnagel a., jike t., iwano s., jauncey d.l., nicolson g.d. & mcculloch p.m. 2005. results of the vlbi experiments conducted with syowa station, antarctica. journal of geodesy 79, 379–388. hinderer j., amalvict m. & luck b. 2002. premières mesures françaises de gravimétrie absolue dans les régions polaires antarctique (terre adélie) et arctique (spitzberg). (first french measurements of absolute gravity in the antarctic [terre adélie] and arctic [spitsbergen] polar regions.) comptes rendus geoscience 334, 819–826. hunter j., coleman r. & pugh d. 2003. the sea level at port arthur, tasmania, from 1841 to the present. geophysical research letters 30, 1401. ivins e.r. & james t.s. 2005. antarctic glacial isostatic adjustment: a new assessment. antarctic science 17, 541–553. james t.s. & ivins e.r. 1998. predictions of antarctic crustal motions driven by present-day ice sheet evolution and by isostatic memory of the last glacial maximum. journal of geophysical research—solid earth 103, 4993–5017. king r.w. & bock y. 2005. documentation for the gamit gps analysis software. release 10.2. cambridge, ma: massachusetts institute of technology. kreemer c., holt w.e. & haines a.j. 2003. an integrated global model of present-day plate motions and plate boundary deformation. geophysical journal international 154, 8–34. lambert a., courtier n. & james t.s. 2006. long-term monitoring by absolute gravimetry: tides to post-glacial rebound. journal of geodynamics 41, 307–317. larson k.m. & van dam t. 2000. measuring postglacial rebound with gps and absolute gravity. geophysical research letters 27, 3925–3928. llubes m., lemoine j.m. & rémy f. 2007. antarctica seasonal mass variations detected by grace. earth and planetary science letters 260, 127–136. mäkinen j., amalvict m., shibuya k. & fukuda y. 2007. absolute gravimetry in antarctica: status and prospects. journal of geodynamics 43, 339–357. mitrovica j.x. & forte a.m. 2004. a new inference of mantle viscosity based upon joint inversion of convection and glacial isostatic adjustment data. earth and planetary science letters 225, 177–189. nerem r.s., leuliette e. & cazenave a. 2006. present-day sea-level change: a review. comptes rendus geoscience 338, 1077–1083. ohzono m., tabei t., doi k., shibuya k. & sagiya t. 2006. earth, planets and space 58, 795–804. ramilien g., lombard a., cazenave a., ivins e.r., llubes m., remy f. & biancale r. 2006. interannual variations of the mass balance of the antarctica and greenland ice sheets from grace. global and planetary change 53, 198–208. remy f. & frezzotti m. 2006. antarctica ice sheet mass balance. comptes rendus geoscience 338, 1084–1097. rignot e., bamber j.l., van den broeke m.r., davis c., li y., van de berg w.j. & van meijgaard e. 2008. recent antarctic ice mass loss from radar interferometry and regional climate modeling. nature geoscience 1, 106–110. rignot e. & thomas r.h. 2002. mass balance of polar ice sheets. science 297, 1502. sato t., okuno j., hinderer j., macmillan d.s., plag h.-p., francis o., falk r. & fukuda y. 2006. a geophysical interpretation of the secular displacement and gravity rates observed at ny-ålesund, svalbard in the arctic: effects of the post-glacial rebound and present-day ice melting, geophysical journal international 165, 729–743. sella g.f., dixon t.h. & mao a. 2002. revel: a model for recent plate velocities from space geodesy. journal of geophysical research—solid earth 107, 2081, doi: 10.1029/ 2000jb000033. snajdrova k, boehm j, willis p., haas r. & schuh h. 2006. multi-technique comparison of tropospheric zenith delays derived during the cont02 campaign. journal of geodesy 79, 613–623. tavernier g., fagard h., feissel-vernier m., le bail k., lemoine f., noll c., noomen r., ries j.c., soudarin l., long-term geodetic observations in east antarcticam. amalvict et al. polar research 28 2009 193–202 © 2009 the authors 201 valette j.j. & willis p. 2006. the international doris service: fenesis and early achievements. journal of geodesy 80, 403–417. testut l., wöppelmann g., simon b. & téchiné p. 2006. the sea level at port-aux-français, kerguelen island, from 1950 to the present. ocean dynamics 56, 464–472. toracinta r.e., oglesby r.j. & bromwich d.h. 2004. atmospheric response to modified climap ocean boundary conditions during the last glacial maximum. journal of climate 17, 504–522. tregoning, p., van dam, t., 2005. atmospheric pressure loading corrections applied to gps data at the observation level. geophysical research letters 32, l22310, doi: 10.1029/ 2005gl024104. velicogna i. & wahr j. 2006. measurements of time-variable gravity show mass loss in antarctica. science 311, 1754–1756. wahr j., han d. & trupin a. 1995. predictions of vertical uplift caused by changing polar ice volumes on a viscoelastic earth. geophysical research letters 22, 977–980. white w.b., chen s.c. & peterson r.g. 1998. the antarctic circumpolar wave: a beta effect in ocean–atmosphere coupling over the southern ocean. journal of physical oceanography 28, 2345–2361. willis p., bar-sever y.e. & tavernier g. 2005. doris as potential part of a global geodetic observing system.journal of geodynamics 40, 494–501. willis p., berthias j.p. & bar-sever y.e. 2006. systematic errors in z-geocenter derived from sun-synchronous satellite data: a case study from spot4/doris 1998 data. journal of geodesy 79, 567–572. willis p. & ries j.c. 2005. defining a doris core network for jason-1 precise orbit determination based on itrf2000: method and realization. journal of geodesy 79, 370–378. wingham d.j., sheperd a., muir a. & marshall g.j. 2006. mass balance of the antarctic ice sheet. philosophical transactions of the royal society a 364, 1627–1635. wolff e.w., fischer h., fundel f., ruth u., twarloh b., littot g.c., mulvaney r., rothlisberger r., de angelis m., boutron c.f., hansson m., jonsell u., hutterli m.a., lambert f., kaufmann p., stauffer b., stocker t.f., steffensen j.p., bigler m., siggaard-andersen m.l., udisti r., becagli s., castellano e., severi m., wagenbach d., barbante c., gabrielli p. & gaspari v. 2006. southern ocean sea-ice extent, productivity and iron flux over the past eight glacial cycles. nature 440, 491– 496. woodworth p.l., pugh d.t., meredith m.p. & blackman d.l. 2005. sea level changes at port stanley, falkland islands. journal of geophysical research—oceans 110, c06013, doi: 10.1029/2004jc002648. wöppelmann g., bouin m.n. & altamimi z. 2008. terrestrial reference frame implementation in global gps analysis at tiga ulr consortium. physics and chemistry of the earth 33, 217–224. wöppelmann g., martin miguez b., bouin m.n. & altamimi z. 2007. geocentric sea-level trend estimates from gps analyses at relevant tide gauges world-wide. global and planetary change 57, 396–406. zwally h.j., giovinetto m.b., li j., cornejo h.g., beckley m.a., brenner a.c., saba j.l. & yi d. 2005. mass changes of the greenland and antarctic ice sheets and shelves and contributions to sea-level rise: 1992–2002. journal of glaciology 51, 509–527. long-term geodetic observations in east antarctica m. amalvict et al. polar research 28 2009 193–202 © 2009 the authors202 no job name approaching the north: norwegian and russian foreign policy discourses on the european arcticpor_165 439..450 leif christian jensen & pål wilter skedsmo fridtjof nansen institute, po box 326, no-1326 lysaker, norway abstract the aim of this article is to identify norwegian and russian official foreign policy discourses on the european arctic, and how perceived challenges are understood, framed and presented by the governments in their respective countries. the article makes use of discourse analysis to grasp how the norwegian “high north” strategy is framed by the norwegian government and, likewise, how the russian approach to the european arctic is framed by the russian government. the empirical foundation is a study of primary texts such as white papers, official reports, speeches and strategies. we find that the norwegian approach to the high north features in a powerful official discourse resulting from a robust and broad domestic discursive mobilization. the russian approach is that of an increasingly assertive nation for which the zero-sum game and relative gains seem to be the main rationale, judging by the official discourse. the russian approach is not as coherent or based on a broad discursive mobilization as in norway’s case. we identify energy, security, the economy and the environment as key discursive nodal points that the foreign policy discourses of the two countries evolve around: we find that both countries regard the european arctic’s potential as a future energy province to be the region’s most prominent aspect. the discourses show that energy is regarded to be of vital national interest, but the countries have differing perceptions on international cooperation. however, as the countries have some important common frames of references, a favourable climate for extended future cooperation could be further developed. keywords discourse; energy; european arctic; high north; russia. correspondence leif christian jensen, fridtjof nansen institute, p.o. box 326, no-1326 lysaker, norway. e-mail: lcj@fni.no doi:10.1111/j.1751-8369.2010.00165.x in this article we analyse norwegian and russian official foreign policy discourses on the european arctic. our analysis uses data contained in norwegian government documents, key speeches by russian president putin and official documents from russian authorities. we use these texts to map how challenges and opportunities in the european arctic are perceived and framed in norway and russia by the authorities. as neighbouring states, the two countries will always have to reach an accommodation with each other in the north, and work closely together from time to time on certain issue areas. among already existing collaborative arrangements we find the joint russian–norwegian fisheries commission (established in 1975) and the joint commission on environmental protection (established in 1988). in addition, norway and russia cooperate on the multilateral level within the framework of the barents euro-arctic region, established in 1993, and the arctic council (1996). however, it is not within the scope of this article to assess or evaluate these collaborative arrangements. literature on such arrangements in the arctic (stokke & hønneland 2007), on cooperation on fishery management (henriksen et al. 2006; hønneland 2006), on relations between the military and the non-military sectors (åtland 2008, 2009), and on discourses on environmental cooperation between russia and the west (hønneland 2003) is a relevant backdrop to our study. our aim, though, is somewhat different as we explore what the foreign policy discourses in both countries say with regard to the perceived opportunities and challenges in the european arctic. discourse plays a crucial part in understanding politics and policies because ultimately it is through language we understand, construct and make sense of the world. the european arctic is at the head of the norwegian political agenda in a way that has not been seen since the days of the cold war. it is especially apparent in polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 439 mailto:lcj@fni.no the significant discursive mobilization of recent years, comprising an increased production of government documents and a widening debate in the norwegian media (jensen 2007; hønneland & jensen 2008). in march 2003, the norwegian ministry for foreign affairs put together a high north commission, which resulted in an official norwegian report in december the same year (ecna 2003). in the autumn of 2005, the newly elected coalition government officially declared: the government regards the northern areas as norway’s most important strategic target area in the years to come. the northern areas have gone from being a security policy deployment area to being an energy policy power centre and an area that faces great environmental policy challenges. this has changed the focus of other states in this region. the handling of norwegian economic interests, environmental interests and security policy interests in the north are to be given high priority and are to be seen as being closely linked. (office of the prime minister 2005) the norwegian government’s high north strategy (ministry of foreign affairs 2006) and new building blocks in the north (norwegian government 2009) set out to translate the government’s ambitions into practical challenges and opportunities facing norway in the north. norwegian action and foreign policy interests in the european arctic depend on relations at several levels with russia. there is little mention in official discourse or public media concerning the russian authorities’ perceptions of the european arctic. in this article we use discourse analysis to interpret the framing of the official discourse in norway, and attempt to do something similar on the russian side. we formulate the following research questions. how are the approaches to the european arctic framed through the foreign policy discourses in norway and russia, and what are the discursive nodal points these discourses evolve around? we start out with a description of our theoretical and methodological point of departure. we then turn to the specific question posed above, and commence our analysis of foreign policy discourses in norway and russia. point of departure there are many ways to depict and analyse policy formations, but as mentioned above we have opted for a discursive approach. discourse analysis is—although the name could indicate otherwise—an integrated theoretical and methodological approach to analysis. it is a complete package containing epistemological premises concerning the role of language in the social construction of the world. in the archaeology of knowledge (1972), foucault’s point of departure is that there exists a set of rules that decides which statements will be accepted as both meaningful and true within a specific historical context. this implies that he understands discourse as including something in addition to speech, words and text. discourse is where meaning is constituted and established, as representations of the physical world are negotiated and confirmed. when any given representation is institutionalized, it gains hegemony. discourse theory is concerned with epistemology, e.g., how meaning and knowledge are created and reproduced, rather than with ontological premises, which concerns itself with the basic nature of things, the essence of “being” itself (neumann 2001; schiffrin et al. 2003). discourse analysis contains theoretical models and methodological guidelines about conducting research in a given field. lastly, it offers special techniques for analysing language as data. discourse analysis combines theory and method, and it is essential to accept its basic epistemological principles outlined above before using it as a method in research (winther jørgensen & phillips 1999). we decided, therefore, to present theory and method under the same heading to illustrate this general point, and because it makes sense from a practical point of view. for the same reasons, we do the same for the presentation and analysis of our data. we define a discourse as “an interrelated set of texts, and the practices of their production, dissemination, and reception, which brings an object into being” (parker 1992; quoted in phillips & hardy 2002: 3). for example, a body of texts of various kinds related to development and environmental management has brought the concept of sustainable development into being, and these discursive practices continue to affect the discourse on sustainable development. as philips & hardy note: discourses are embodied and enacted in a variety of texts although they exist beyond the individual texts that compose them . . . texts are not meaningful individually; it is only through their interconnection with other texts, the different discourses on which they draw, and the nature of their production, dissemination, and consumption that they are made meaningful. (phillips & hardy 2002: 3–4) one uses discourse analysis to understand how change occurs or status quo is maintained through processes of embedding, or as part of an already established hegemony in political discourse. the implications of political discourses on the respective domestic scenes in norway and russia are that we, as analysts, are looking at constraints that shape their foreign policies—a kind of framework within which the foreign policy of either country can take place (larsen 1997). what we will try to do in this article is to show how, whether in norway or russia, foreign policy issues are framed as certain topics norwegian and russian discourse on the european arctic l.c. jensen & p.w. skedsmo polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd440 are included and others excluded in discourse. further, we will look for what laclau & mouffe (1985) brand nodal points. the central implication is that discourses evolve around certain concepts or statements that tend to have a privileged standing within the discourse. this said, such nodal points can only “obtain partial fixation” (åkerstrøm andersen 2003: 51) because they will always be in the midst of discursive battles, and because discourses are always in flux. still, certain concepts will be less disputed, and treated more as truisms, than others. the discourse analyst interrogates taken-for-granted meanings in texts from the specific setting she reads. combined with relatively small and context-specific data sets this critical potential makes it difficult to claim external validity (tonkiss 1998). but, “[d]iscourse analysis fits into a broad range of social research methods which between them seek to analyse general social patterns but also to examine the devil in the detail” (tonkiss 1998: 260). thus, the analyst seeks to establish internal validity, or at least a plausible narrative (czarniawska 2004), which, in addition to being interesting and having a value in itself, hopefully will say something of more general significance, even though it will not be generalizable in a strict positivist methodological sense. there will always be other points of view that see reality differently, and it is possible to identify alternative discourses. however, the purpose of this article is to take a closer look at what we term official foreign policy discourses in norway and russia related to the european arctic. these discourses have to be constructed by us as analysts based on a plausible interpretation of the empirical data available. they are not preformed entities, “ready to be plucked from the air and waiting to be identified” (jensen 2007: 248). another more fundamental matter is what we can do to convince you as a reader that our representation is accurate and fair. according to a social constructivist theory of knowledge, where a given representation of the world is just one of many possible representations, it is an unanswerable question (winther jørgensen & phillips 1999). naturally, other choices could be made and other discourses explored. our delimitations and constructions are, however, based on an assumption that they best represent the slices of reality we seek to convey (hønneland 2005). this assumption relies in turn on our document studies that we believe offer a solid vantage point on the most typical and relevant aspects of norwegian and russian foreign policy discourse in the north since the turn of the millennium. discourse analysis gives epistemological and methodological priority to the study of primary texts (hansen 2006), such as presidential statements and official policy documents that are our main sources of data in this study. these so-called monuments (neumann 2001) or primary texts are often created in the context of an ongoing discursive battle and have, at least in theory, formed, absorbed and grasped the strongest representations. when selecting primary texts, we were at pains to meet the following three criteria: the texts should be characterized by the clear articulation of identities and policies; they should be widely read and attended to; and they should have the formal authority to define a political position (hansen 2006). we argue that our chosen texts score high on all of these criteria, and can therefore with relative confidence be branded primary texts or monuments in what we define as the discursive field of the european arctic. russian presidential statements are taken into account and referred to by politicians and the public—and by governments—throughout the world. and equally important, the selected texts are all articulated by formal political authority, which is of course crucial as they are intended to represent the countries’ approaches to the european arctic. the texts can also have or acquire power by repeating, confirming, strengthening and/or qualifying a certain ideological position, and by their context-specific appearance. they both have and generate power by being perceived as relevant and important enough to participate and take centre stage in such important discourses (berge 2003). texts like the ones making up our data set the agenda and shape the issues at hand, and they frame and produce representations of foreign policy. powered by their respective roles as institution or president, the actors have a certain authority and power to define how reality should be perceived (berge 2003; hansen 2006). in addition, they enjoy official prestige and authority as speech acts (searle 1969). it is up to policymakers and bureaucrats on either side to give these policy statements and speech acts substance, and respond with practical steps in the policy areas in question. in this article we decided to leave the “practical steps” alone, and concentrate on the discursive level. obviously, in politics, as in life in general, what is being said and what is being done are frequently at odds. on the other hand, statements from a russian president, in light of his extensive executive powers, should not be underestimated, even though the statements are—as this article will show—often rather general. all quotations in this article, which are used as documentation, exemplification and representation of the norwegian foreign policy discourse, are taken from officially translated versions of the following public documents: the norwegian government’s high north strategy (ministry of foreign affairs 2006), the soria moria declaration on international policy (office of the prime minister 2005) and the white paper opportunities and challenges in the north (ministry of foreign affairs 2005). in addition, we have analysed the official norwegian report towards norwegian and russian discourse on the european arcticl.c. jensen & p.w. skedsmo polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 441 the north! challenges and opportunities in the high north (ecna 2003) and new building blocks in the north: the next step in the government’s strategy for the high north (norwegian government 2009). these documents are not available in officially translated english versions, and the translations of these and various media sources are our own. on the russian side, we selected president putin’s annual addresses to the federal assembly throughout his two presidential terms in 2000–08 as the key documents (putin 2001, 2002, 2003, 2004, 2005, 2006, 2007). we studied the speeches in the original russian language version, available at the russian president’s official website, but for the purpose of this article we use the officially translated versions made available through the same website. we also rely on the energy strategy for russia towards 2020 (gazprom 2003), president putin’s address to the state council on russia’s development strategy (putin 2008) and russia’s arctic strategy issued by the russian security council (2009a) to get a more elaborate understanding of russia’s approach to the european arctic. an official english summary is available for the energy strategy; putin’s address to the state council is available in an official english translation; and the security council’s arctic strategy has been translated from the original russian by the authors. albeit general in perspective, such documents portray tendencies over time, have the authority to define an issue and enjoy epistemological priority (hansen 2006). norwegian high north discourse skagestad (n.d.) observes that the phrase “high north” was introduced as the english equivalent of the norwegian term nordområdene (the northern areas) in the mid1980s, eventually becoming adopted by the norwegian authorities at the beginning of the current century. according to skagestad: “the concept has no immediate corresponding counterpart in academic or political discourse outside of norway, and it is not self-explanatory to foreigners” (n.d.). the official norwegian understanding of the “high north”, at least geographically, was presented in the norwegian government’s high north strategy (ministry of foreign affairs 2006), which was released on 1 december 2006. the high north is a broad concept both geographically and politically. in geographical terms, it covers the sea and land, including islands and archipelagos, stretching northwards from the southern boundary of nordland county in norway and eastwards from the greenland sea to the barents sea and the pechora sea. in political terms, it includes the administrative entities in norway, sweden, finland and russia that are part of the barents co-operation. furthermore, norway’s high north policy overlaps with the nordic co-operation, our relations with the us and canada through the arctic council, and our relations with the eu through the northern dimension. (ministry of foreign affairs 2006: 13) the same government’s definition of the high north seemed to have opened up somewhat three years later. the government’s policy does not give a precise definition of what it reads into the expression “the high north”, nor whether it limits the high north to norwegian territory. substantial norwegian interests are likely to be affected by developments wherever they take place in the circumpolar and arctic region; indeed, international terminology tends to use “high north” and “arctic” more or less synonymously [in fact, the term “high north” is not employed in international discourse; see skagestad (n.d.)]. norway’s strategic high north policy exists in a certain geo-political environment. norway remains committed to maintaining its active dialogue with neighbours, partners and allies on matters related to the high north, and to do more to promote norway’s high north policy in international and regional forums. wider international cooperation in the high north and circumpolar areas, and with russia in particular, should prove beneficial for our part of the country as well. (norwegian government 2009: 7; translated by the authors) it is interesting to note how the very precise geographical definition in the 2006 document has disappeared in favour of a vaguer and more open-ended understanding of the high north. such a change could very well indicate some sort of shift in the norwegian approach, or at least be a symptom of a change in priorities, focus or direction in the government’s approach to the high north. the more general point one could make from this is that the texts are clearly interrelated, but at the same time are different enough to make us see that discourses are dynamic and always in flux. the main purpose of the government’s high north strategy is to “coordinate efforts in all fields relating to the development of the high north” (ministry of foreign affairs 2006: 5). furthermore, the overall objective of the government’s policy on this matter is to “create sustainable growth and development in the high north” (ministry of foreign affairs 2006: 7). such a sentiment was formulated in a very similar way by the previous government three years earlier. this shows how the discourse consists of an “interrelated set of texts” (parker 1992 quoted in phillips & hardy 2002: 3). through the active use of natural resources, a pro-active foreign policy and high environmental norwegian and russian discourse on the european arctic l.c. jensen & p.w. skedsmo polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd442 standards, norway intends to make the high north a model of sustainable development, where culture and nature provide the foundations of innovation in commerce and industry and collaboration between nation-states. (ecna 2003: 9; translated by the authors) the high north has been revitalized by a discourse on the prospects that the barents sea could become a new, strategically important petroleum province. this discourse was apparent in public documents under other governments before the high north was declared top priority in the autumn of 2005. there are also major challenges in the foreign policy field. other countries are showing a growing interest in norwegian and russian petroleum resources. this is partly because these resources are located in politically stable areas, and many countries are concerned about securing their energy supplies. this makes the high north more interesting than many other areas that are rich in energy sources. periods when there is an insufficient supply of energy may give rise to high expectations and political pressure. it cannot be taken for granted that norwegian interests will always coincide with those of key partners. it is therefore important to ensure that norway’s interests continue to determine developments in the norwegian part of the high north. (ministry of foreign affairs 2005: 7) and this was reiterated and made concrete as part of placing the high north at the top of the policy agenda by the current government one year later. the government’s aim is that norway will be the best steward of resources in the high north, with oil and gas operations that meet very stringent environmental standards, and with continual knowledge generation, research and development in the petroleum sector . . . it is also likely that the barents sea will become increasingly important in the global energy supply context due to the political will in many countries to reduce dependency on supplies from the middle east. the resources in the barents sea could provide long-term secure energy supply to the markets in europe and the us within a sustainable framework. (ministry of foreign affairs 2006: 55) a consequence of not having found a norwegian equivalent to the giant russian gas field shtokman (shtokmanovskoye) was that the main focus in the public high north debate in norway was slowly turning towards what might or might not happen petroleum-wise on the russian side. this was regarded as important, whereas speculation reached new levels on what role norway and norwegian companies could or could not play in different outcomes. sentiment in general, mirrored and powered by the media coverage (hønneland & jensen 2008) since the high north became a major concern in norway, swung largely in step with signals coming out of the kremlin and gazprom headquarters. questions about norway’s potential role in the development of the shtokman field have flourished, and have set the tone and the pace of public discourse through the norwegian media: a quotation from a story in a major norwegian financial newspaper represents this in a telling way. confirmation came yesterday from [the norwegian energy company] statoil and the norwegian petroleum directorate that the well known as uranus, sited 125 km north-east of nordkapp [in northern norway], was dry. the announcement came just as the barents fever was about to infect all of us. [the northern norwegian town of] hammerfest is sinking under the weight of snow white money [a reference to a major liquefied natural gas extraction project]. the italian oil conglomerate eni wants to develop the goliath field [off northernmost norway]. statoil and [the norwegian energy company] hydro want to be part of russia’s gigantic shtokman development. norwegian foreign minister jonas gahr støre talks so incessantly about oil and the high north, he wouldn’t look amiss in a boiler suit and hard hat. oil expert johan petter barlindhaug, who enjoys the backing of the government and statoil, has turned the map upside down in declaring northern norway the centre of europe’s next oil klondike. behind everything glow increasingly seductive oil and gas prices. it is probably only the socialist left party and a handful of aggravated environmentalists that want to slow the pace, setting their hopes on the integrated management plan for the barents sea, due out before easter. ironically, the most dependable ally of the environmentalists at the moment could be the geology of the norwegian barents sea. the dry uranus hole is not the first geological let-down to face oil devotees. since the summer of 1980, sixty-five wells have been drilled up north, resulting in only two promising fields: the snow white gas field and the goliath oil field. and in southern norwegian terms, they are not particularly extensive either. (løvås 2006: 2; translated by the authors) one of the main characteristics of norway’s high north strategy remains the discursive mobilization, not least in newspapers nationwide (jensen 2007; hønneland & jensen 2008). a wide range of actors have felt called to explain their views, although nothing significantly has really happened materially in the north since the debate began. the urgency of issues concerning the high north norwegian and russian discourse on the european arcticl.c. jensen & p.w. skedsmo polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 443 can also be defined in terms of speech acts: as a region that is “talked and written into existence” (neumann 1994: 59) in much the same way as the barents euroarctic region itself was one and a half decades earlier. instead of postulating a given set of interests, a regionbuilding approach investigates interests where they are formulated, i.e., in discourse. in addition to its place at the top of the political agenda, the high north is clearly of considerable interest to the general public. one could even say that the texts and utterances of the norwegian foreign minister have in fact revitalized the dynamics of the high north debate. policy documents have framed the issue in a certain light, and have approached the high north from a certain angle, which has made us understand, talk and act in a certain way. on the other hand, the documents and the public deliberations have reinforced, cultivated and shaped one another. the documents have given rise to opinions, and the public discourse has shaped the next policy document, and vice versa (jensen 2007; hønneland & jensen 2008). the norwegian government has made an open commitment to protect and promote interests in an area of great opportunities and increasing civil strategic importance. norwegian interests in the high north will be safeguarded primarily by strengthening our presence and increasing the level of activity in a number of policy areas at both national and international level. (ministry of foreign affairs 2006) for instance, it would mainly be up to the norwegian ministry of defence to figure out what practical measures need to be taken by the norwegian navy and coastguard in order to live up to the promise of a strengthened presence in the high north. thus, we see how foreign policy discourses must not only be interpreted by outsiders, such as academics and observers abroad, but also by parts of the state apparatus. if the political discourse, as voiced by its most eager ambassador—the norwegian minister of foreign affairs—is to be taken seriously, for instance, the threat of a discursive practice like deploying norwegian armed forces if necessary must be deemed credible by outsiders. as the document makes clear, foreign policy and national policy ambitions are merging and growing ever more tightly linked discursively: development in the north of norway, cooperation with russia and absolute, mutual gains (keohane & nye 1977) are exemplified by the following two quotations. it is the government’s strategy to facilitate the further development of a knowledge-based business sector in the high north, with particular focus on seizing the opportunities in the resource-based sectors. a strong knowledge base in north norway will also be important for the development of cross-border business activity between norway and russia. (ministry of foreign affairs 2006: 65) norway’s partnership and commerce with russia are surging ahead. increasing numbers of norwegian businesses now have a stake in north-west russia, and contact across the border is greater than ever. norwegian and russian businesses are establishing partnerships across ever wider areas. the authorities will take steps to accelerate capacity, building in the private sector in the high north, and promote norwegian business interests in russia. (norwegian government 2009: 50; translated by the authors) moreover, this follows from the main theme of the strategy, which is to “give our [the government’s] policy a more coherent high north focus” (ministry of foreign affairs 2006). in addition to pursuing high politics and protecting vital norwegian national interests from foreign actors, tighter integration is considered “a question of a broad long-term mobilisation of our own strengths and resources in the development of the entire northern part of our country” (ministry of foreign affairs 2006: 5). the norwegian approach ranges across issues as diverse as safeguarding the livelihoods, traditions and cultures of indigenous peoples in the high north, promoting peopleto-people cooperation, and developing policy on future petroleum activities in the barents sea (ministry of foreign affairs 2006). public sentiment declined noticeably after gazprom, the russian energy company in which a controlling stake is held by the russian state, announced in october 2006 that it would proceed with the development of shtokman without norway (i.e., excluding statoil or hydro). all the same, after it became known in october 2007 that the newly merged statoilhydro company would be a partner with gazprom and total—with president putin calling prime minister stoltenberg to personally break the good news—norwegian media redoubled their coverage, and a spirited high north debate ensued. judging from the media debate in the following weeks, putin and russia had literally saved the day in the high north, and helped give the norwegian strategy renewed vitality and substance. perhaps one of the reasons the high north strategy has not really taken off, despite a massive effort by the government, was the lack of success displayed—materially—on the ground. the government clearly found it difficult to convince the public of the material advantages of the enterprise. russian policy discourse on the european arctic as outlined above, our study of the russian policy discourses related to the european arctic rests on a study of norwegian and russian discourse on the european arctic l.c. jensen & p.w. skedsmo polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd444 documents we, in line with hansen (2006), hold that are primary texts, which have epistemological priority to the discourse analyst. on the russian side, there is to a lesser extent a readily apparent policy discourse corresponding to norway’s ambitious high north policy. the russian alternative to norway’s intense discursive mobilization is conspicuous by its absence. this is not to say that northern politics is not discussed in russia, but that it seemingly does not match the forceful debate that has taken place in norway over recent years. parliamentary committees, such as the committee on northern territories and indigenous minorities issues in the council of the federation (komitet soveta federacii po delam severa i maločislennyh narodov) have fairly little power, and the legislation in russia is weaker than the executive powers of the president. yet more powerful is the russian security council, a consultative body to the president. the security council have, among others, issued a strategy for russia’s arctic policies up to 2020 (russian security council 2009b). the presidential statements analysed in this article are rather general in perspective, and, combined with a seeming lack of media discourse on arctic issues in russia, could be interpreted to indicate a lack of discursive mobilization in russia. although issues related to the european arctic are debated and discussed in the russian media, our assessment of russian public discourse is that issues related to the arctic do not take on the same prominence or importance as they do in norway. this observation is based on our day-to-day reading of various russian media sources. let us now turn to what the existing data sources from russian political authorities tell us about the russian approach to the north. firstly, we note that the official discourse in russia conveys a rather fixed view on foreign policy, the rationale and implications of which were clearly summed up by the president. we are building constructive, normal relations with all of the world’s nations—i want to emphasise, with all of the world’s nations. however, i want to note something else: the norm in the international community, in the world today, is also harsh competition—for markets, for investment, for political and economic influence. and in this fight, russia needs to be strong and competitive. (putin 2002) although futile legally (jensen 2008: 585), when a russian submarine planted the russian flag on the seabed at the north pole in 2007 (parfitt 2007), such a discursive practice (neumann 2001) can be taken as an example of russia’s increasing assertiveness. does this imply that russia is pursuing a more confrontational line than norway? president putin has his own views on the west’s interference and interpretations of russian policies. it is far from everyone in the world that wants to have to deal with an independent, strong and self-reliant russia. political, economic and information pressures have become weapons in the global competitive battle today. our efforts to strengthen our state are sometimes deliberately interpreted as authoritarianism. in this respect i want to say that there will be no going back on the fundamental principles of our politics. (putin 2004) the russian president appears to retain the notion of foreign policy as a game, where what is in one state’s interests is automatically in conflict with those of others (morgenthau 1973). in russian political science— politologija—relations between states are typically perceived as a zero-sum game where one state’s gain is another state’s loss. so norwegian financial support for different projects on the kola peninsula, however well intended, risk being perceived ambivalently by russian authorities, or even as instances of hostile strategic interference (skedsmo 2005). as russia balances between a desire to be a reliable trading partner and more hawkish foreign policy aspirations, one notes a sense of antagonism between integration and security, insofar as integration could lead to dependence and a narrowing of the strategic options available (larsson 2006). the russian president sees this as a global battle for access to strategic resources. in this context, it is understandable that the world should be showing growing interest in russia and in eurasia in general. god was generous in giving us natural resources. the result is that we are running up against repeats of the old “deterrence” policy more and more often. but what this usually boils down to, essentially, are attempts to impose unfair competition on us and secure access to our resources. (putin 2008) russia’s understanding of foreign relations as a zero-sum game, where energy takes centre stage, is at odds with norwegian sentiments, where mutual gains are seen to be within reach in international relations. whatever its perspective on foreign relations, norway will have to accept russia’s newfound assertiveness after a historically exceptional period of economic turmoil in the 1990s, during which norway to a greater extent could set the agenda for collaborative arrangements in the north (hønneland 2003, 2005). it was a historical and political anomaly, not likely to be experienced again in the foreseeable future. if energy policy is understood—as one observer notes—to be the “sword and shield of russia’s security policy” (larsson 2006: 291), this could indicate that energy is first and foremost understood in terms of security in russia. indeed, the fact that russia’s arctic strategy norwegian and russian discourse on the european arcticl.c. jensen & p.w. skedsmo polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 445 (russian security council 2009a) is published by the security council could possibly be interpreted as some form of a securitizing move (wæver 1995) on russia’s behalf. however, this rather generally formulated document actually emphasizes several other features of the arctic rather than military security, and is to be found under the heading of “economic security” (ekonomičeskaja bezopasnost’) on the council’s website (russian security council 2009b). the document outlines a number of focus areas for the arctic: the arctic’s potential as a strategic resource base, the arctic as a zone of peace and international cooperation, the arctic’s unique ecosystem and the possibilities for new transport routes. the document states that russia is troubled by what it sees as the increased militarization of the region (russian security council 2009a). on the other hand, it states that the main goal in the third phase leading up to 2020, e.g., from 2016 to 2020, is to secure and transform russia’s arctic zone to have the leading role as the strategic resource base for russia. media reception in the west has largely focused on the “deployment of an arctic force” (bbc 2009) and similar issues (isachenkov 2009; parfitt 2009), but this is perhaps more telling of how the west still interprets russia’s actions in cold war terms. in the russian media, a spokesperson of the security council downplayed the issue related to the deployment of an arctic force (borisov 2009). to sum up, we find russia’s arctic strategy to be rather general and cautious in its approach. however, it shows that russia fully acknowledges the potential of its arctic areas to secure the socioeconomic development, and it is in this sense that it seems most reasonable to interpret the document. to utilize the arctic zone of the russian federation as a strategic resource base for the russian federation in order to secure the socio-economic development of the country. (russian security council 2009a) possibly in contradiction to russia’s wish to protect its strategic resources is its expressed need for foreign investments and technology for its extraction sector. putin has touched on the sector’s need of investments on several occasions. the general message seems to be that russia wants to attract and encourage foreign investors, but keep foreign interference well away from the strategically important sector. we already feel confident in the mining and extraction sector. our companies in this sector are very competitive. gazprom, for example, has just become the third biggest company in the world in terms of capitalisation, while at the same time maintaining quite low tariffs for russian consumers. this result did not just come about all on its own, but is the result of carefully planned action by the state. (putin 2006) political discourse matters, but it is connected to materiality such as the demand and delivery of petroleum. securing the latter requires a favourable investment climate and transparent regulation of property rights. putin has addressed ways of encouraging investment in several speeches. we must take serious measures to encourage investment in production infrastructure and innovative development while at the same time maintaining the financial stability we have achieved. russia must realise its full potential in high-tech sectors such as modern energy technology, transport and communications, space and aircraft building. (putin 2006) although russia seems to be lagging behind in terms of exploration, the investment climate is uncertain at best. although of growing concern, there are no signs as of yet of a reform of the energy sector. russia’s need for investment and technology is directly related to discussions on foreign participation and partnership. for instance, recognizing the inefficiency of the operating fields shows that russians understand the need for foreign investments and solutions. yet another problem is that russian oil fields burn more than 20 billion cubic metres of accompanying gas every year, and that is the minimum estimate. and yet, elsewhere in the world, there is a whole system of measures that has already proven its effectiveness. (putin 2007) although statoilhydro is involved in the development of the shtokman field, it remains to be seen to what extent russia opens the door for foreign investment and participation. previous vacillation on foreign participation in shtokman does not bode well for those hoping for a transparent and consistent policy to emerge. russia inherited the soviet subsidy system of the north (blakkisrud & hønneland 2006a), and president yeltsin oversaw its continuation. the soviet union was characterized as “an administrative ordering of nature and society, a high-modernist ideology, an authoritarian state and a prostrate civil society that lacks the capacity to resist these plans” (scott 1998: 4–5). these traits are not, however, only relics of the past: the same mechanisms can still claim some relevance today. a hallmark of the system was the inherently territorial tenor of soviet high north policies: the north was considered to be a world apart, the complex challenges of which should be seen and resolved as a whole. . . . the main problem facing today’s russian government is neither the space in itself nor its northernness, but the fact that it has inherited an economic geography established in deliberate norwegian and russian discourse on the european arctic l.c. jensen & p.w. skedsmo polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd446 defiance of the constraints of both distance and climate. (blakkisrud & hønneland 2006b: 193) the post-soviet presidential administrations have struggled to hammer out an acceptable power-sharing agreement between the regional and federal governments, asyeltsin encouraged the regions to “take as much sovereignty as they could swallow” (blakkisrud & hønneland 2006a: 13); whereas president putin has sought to strengthen the executive. we set ourselves the objective of building an effectively functioning executive vertical power structure . . . a year ago it was clear that in order to ensure the success of the strategic transformations we wished to undertake, we would have to bring order to relations between the federal and regional authorities, and that not having clearly delimited powers and effective mechanisms for cooperation between the different levels of power would result in greater economic and social losses. we need a consolidated and effective state power system in order to act on urgent social and economic problems and security issues. (putin 2001) increasing centralization seems to have been an important theme of both putin’s terms in office. however, perceptions of the north lost much of their territorial anchor, and became functional (blakkisrud & hønneland 2006a). in light of the dismantling of the soviet system of subsidies, the profitable north has moved into the fore, sidelining unprofitable areas that have had to accept a diminishing role and less attention. the north as a future energy province is what really matters, as several of the quotations above indirectly confirm. however, certain securitizing moves are deployed by russia, although this should not be exaggerated. but slightly more hawkish rethoric and practices set russia apart as an ambitious nation aiming to regain superpower status, compared with the more collaborative tone emanating from norway. to sum up, official russian discourse appears fragmented compared with norwegian discourse. as noted above, a wide and public debate over russia’s policy to the north is almost absent compared with norway. the way in which russia’s arctic strategy was published illustrates this: rather than being forcefully branded, as the norwegian high north strategies have been, with several cabinet members participating at press conferences, russia’s arctic strategy was published relatively discretely, with just a press release on the security council’s website. however, it was soon picked up by russian and international media. vacillating about partnerships for the shtokman development could seem to suggest a rather incoherent policy on the north in general, and particularly on offshore development. certain fundamental principles are clearly voiced in the dominant political discourse, although market principles do not always march in step with the protection of strategic resources, and in this sense, national control seems to be the fundamental and prevailing narrative. it should also be noted that this rivalry between securing the interests of the state and letting the private sector go about its business in a relatively uninhibited fashion will probably continue to form russian policy discourses. embedded within russian political discourses on energy, foreign intervention and business participation compete with concerns to safeguard strategic resources, not to mention the strengthening of executive power. thus, we find that russia does not have a consolidated foreign policy discourse focusing on collaboration and development of business in the european arctic. furthermore, russia does not have an equivalent to the forceful discursive mobilization overseen by the norwegian government. on the contrary, russian policies related to the arctic are embedded in other political discourses, such as discourses related to security and sovereignty, and development of the country’s socioeconomic situation. a central implication of this is that russia’s approach to the arctic could perhaps be said to be more functional and ad hoc than norway’s more holistic and all-inclusive approach. sharing discursive nodal points in the north in this article we have analysed norwegian and russian foreign policy discourses on the european arctic. these discourses contain certain nodal points that partially fix the discourses. perceptions and discourses evolving around nodal points are embedded in the historical experiences and different political traditions of the two nations. based on the empirical data discussed so far we have identified four nodal points that the norwegian and russian foreign policy discourses on the european arctic evolve around. these are energy, security, the economy and the environment. the four nodal points are perhaps not surprising in themselves, but by way of identifying them and showing how they are emphasized in discourses, this can shed new light on the norwegian and russian approaches to the european arctic. we have witnessed the norwegian discourse on its northern politics speed up significantly since 2005. we have seen how the norwegian approach to the high north features in a powerful official discourse resulting from a robust and broad domestic discursive mobilization. official norwegian messages are consistent, seeking to balance norway’s global position as a small state with energy-driven ambitions in the european arctic. this dual role of small state and big player results in a foreign norwegian and russian discourse on the european arcticl.c. jensen & p.w. skedsmo polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 447 policy discourse that seems to be as much about getting the attention and backing of friends and allies, as it is about minimizing meddling in the sphere of norwegian interest. the aim seems to be to leave as much room for manoeuvring as possible. the approach is coherent in the sense of seeking to embrace everything associated with the north, such as fisheries, indigenous people and the protection of endangered species. the official norwegian discourse clearly rides on an energy plot, and on the perceptions of the european arctic as a future petroleum province of regional or even global significance. armed with cutting edge technology, but lacking viable known reserves, norway remains firmly focused on pursuing mutually beneficial relations with russia. the russian approach is that of an increasingly assertive and self-confident nation, for which—judging by the official discourse—the zero-sum game and relative gains seem to be the main rationale. nevertheless, the russian approach is not particularly coherent or based on a broad discursive mobilization in the same way as the norwegian approach. rather, it embodies a more functional approach to petroleum as a vital strategic resource. the north as such lacks the same discursive position in russia as in norway. it is not hard to see that russia seems reluctant to give up control over vital and strategic resources, and the prevailing zero-sum thinking can seriously dampen the prospects of fruitful relations in the areas of technology and business with western countries on the russian continental shelf. given russia’s habit of sending mixed messages—calling for cooperation, while blaming the west in general, and nato in particular, for expansionism—russia may look as if it lacks a coherent strategy, or one that resists interpretation. but on the other hand, speeches given by former president putin do send a rather consistent message concerning russia’s priorities. despite our finding that russia does not have a coherent discourse on the arctic, to the extent that norway has on the high north, our data suggest that russia’s approach to the arctic evolves around corresponding themes. we find that both countries regard the european arctic’s most important feature to be its prospects as a resource province, with more or less emphasis on security. norwegian and russian discourses are both oriented towards protecting national interests, albeit the rhetoric is definitely more assertive on the russian side. calls for collaboration in business development have certainly been an issue, especially when the much-debated shtokman field is in the picture. but as norway expressed fresh optimism after statoilhydro was taken on board by the russians, norway still seems to have a problem with its image, both at home and abroad. the already difficult task of projecting a credible image as a world leader in environmental friendliness, while overseeing an economy that is hostage to fossil fuels, is particularly apparent in the high north. being a credible steward and protector of the environment while earning money from petroleum extraction in the very same region is extremely difficult— at least to communicate convincingly. in norway, the petroleum debate related to the barents sea has pitted extraction against protection: as the argument for extraction goes, it would be better for the environment if norwegian petroleum companies did the drilling because they know more about environmentally friendly drilling than their russian counterparts (jensen 2007). that norway is a better friend of the environment than russia is a broad and largely unquestioned assumption in the norwegian public sphere. in its energy strategy, however, russia admits facing “a lot of ecological problems” (gazprom 2003). they will be addressed by developing “low-waste technologies”, and steps will be taken “to come closer to the european ecological standards” (gazprom 2003). perhaps needless to say, norwegian perceptions of their own and russia’s environmental capabilities have practical consequences in terms of how norway as a country approaches russians and challenges in the north, where russia is both part of the problem and part of the solution. finally, based on the four common nodal points it is tempting to ask whether the norwegian and russian approaches to the european arctic are that different after all? both countries are producers, and share complementary needs and assets: russia admits to a lack of technological competence in offshore drilling under demanding conditions such as the arctic, whereas norway is worried about a shortage of viable petroleum fields in the norwegian sector of the barents sea. there are discursive and material forces pulling in different directions, making the climate for extended bilateral cooperation far from straightforward. but, in their various current and future efforts to protect the sensitive environment close to home, norway and russia could very well end up discovering that they have more in common than they usually seem to recognize. the analytical foundation of this article is discourse analysis. we tried to spell out at the beginning, and to show implicitly throughout this article, that texts possess power in their own right, and that understanding discourse is crucial in making better sense of foreign policy formation. discourse analysis has enabled us to investigate how norway’s and russia’s approaches to the north are framed, socially produced and maintained, and how they are always in change. we feel there is a great, unfulfilled need for more interdisciplinary research into such diverse, highly technical, complex, and at the same time often politicized issues that polar research includes. norwegian and russian discourse on the european arctic l.c. jensen & p.w. skedsmo polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd448 acknowledgements we would like to thank two anonymous referees for their helpful comments and suggestions that significantly helped to improve the first version of this article. lcj would like to thank the norwegian ministry of defence for funding the study upon which his contribution to this article is based. we would also like to thank chris saunders for assistance with language. references åkerstrøm andersen n. 2003. discursive analytical strategies: understanding foucault, koselleck, laclau, luhmann. bristol: policy press. åtland k. 2008. mikhail gorbachev, the murmansk initiative, and the desecuritization of interstate relations in the arctic. cooperation and conflict 43, 289–311. åtland k. 2009. russia’s northern fleet and the oil industry—rivals or partners? petroleum, security, and civil–military relations in the post–cold war european arctic. armed forces & society 35, 362–384. bbc 2009. russia outlines arctic force plan. bbc news, 27 march. accessed on the internet at http://news.bbc.co.uk/ 2/hi/europe/7967973.stm on 10 april 2009. berge k.l. 2003. hvor er makten i teksten? (where is the power in texts?) in k.l. berge et al. (eds.): maktens tekster. (the texts of power.) pp. 24–42. oslo: gyldendal akademisk. blakkisrud h. & hønneland g. 2006a. the burden and blessing of space. in h. blakkisrud & g. hønneland (eds.): tackling space: federal politics and the russian north. pp. 193–203. lanham, md: university press of america. blakkisrud h. & hønneland g. 2006b. the russian north: an introduction. in h. blakkisrud and g. hønneland (eds.): tackling space: federal politics and the russian north. pp. 1–24. lanham, md: university press of america. borisov t. 2009. bez boevyh pingvinov: rossija sozdaet arktičeskuju gryppirovku vojsk bez militarizacsii regiona. (no fighting penguins: russia creates arctic force without militarizing the region.) rossijskaja gazeta, 30 march. accessed on the internet at http://www.rg.ru/2009/03/30/ arktika.html on 12 april 2009. czarniawska b. 2004. narratives in social science research. london: sage publications. ecna (expert commission for the northern areas) 2003. mot nord! utfordringer og muligheter i nordområdene. nou 2003:32. (towards the north! challenges and opportunities in the high north. nou 2003:32.) oslo: government administration services. accessed on the internet at http://www.regjeringen.no/rpub/nou/20032003/032/ pdfs/nou200320030032000dddpdfs.pdf on 15 feburary 2008. foucault m. 1972. the archaeology of knowledge. london: routledge. gazprom 2003. energičeskaja strategija rossii na period do 2020 goda. (russia’s energy strategy towards 2020.) moscow: gazprom. english summary available on the internet at http://ec.europa.eu/energy/russia/events/doc/ 2003_strategy_2020_en.pdf. hansen l. 2006. security as practice: discourse analysis and the bosnian war. london: routledge. henriksen t., sydnes a.k. & hønneland g. 2006. law and politics in ocean governance: the un fish stocks agreement and regional fisheries management regimes. leiden: martinus nijhoff publishers. hønneland g. 2003. russia and the west: environmental cooperation and conflict. new york: routledge. hønneland g. 2005. barentsbrytninger: norsk nordområdepolitikk etter den kalde krigen. (barents breaking: norweigan high north politics after the cold war.) kristiansand: høyskoleforlaget. hønneland g. 2006. kvotekamp og kyststatssolidaritet: norsk–russisk fiskeriforvaltning gjennom 30 år. (quota battle and coastal state solidarity: norwegian–russian fisheries management through 30 years.) bergen: fagbokforlaget. hønneland g. & jensen l.c. 2008. den nye nordområdepolitikken: barentsbilder etter årtusenskiftet. (the new high north politics: barents images after the turn of the millennium.) bergen: fagbokforlaget. isachenkov v. 2009. russia plans to create arctic military force. washington times, 27 march. accessed on the internet at http://www.washingtontimes.com/news/2009/ mar/27/russia-plans-to-create-arctic-military-force-1 on 10 april 2009. jensen l.c. 2007. petroleum discourse in the european arctic: the norwegian case. polar record 43, 247–254. jensen ø. 2008. kontinentalsokkelens avgrensning utenfor 200 nautiske mil: norske og russiske perspektiver i de nordlige havområder. (delimitation of the continental shelf beyond 200 nautical miles: norwegian and russian perspectives in the northern maritime areas.) internasjonal politikk 66, 563–589. keohane r.o. & nye j.s. 1977. power and interdependence: world politics in transition. boston: little, brown and company. laclau e. & mouffe c. 1985. hegemony & socialist strategy: towards a radical democratic politics. london: verso. larsen h. 1997. foreign policy and discourse analysis: france, britain and europe. london: routledge. larsson r.l. 2006. russia’s energy policy: security dimensions and russia’s reliability as an energy provider. stockholm: swedish defence research agency. løvås j. 2006. barentsbløffen. (the barents bluff.) dagens næringsliv, 23 march, p. 2. ministry of foreign affairs 2005. report no. 30 (2004–2005) to the storting. opportunities and challenges in the north. oslo: norwegian ministry of foreign affairs. accessed on the internet at http://www.regjeringen.no/upload/kilde/ ud/stm/20042005/0001/ddd/pdts/stm200420050001ud_ dddpdts.pdf on 15 feburary 2008. ministry of foreign affairs 2006. the norwegian government’s high north strategy. oslo: norwegian ministry of foreign affairs. accessed on the internet at http://www.regjeringen. no/upload/ud/vedlegg/strategien.pdf on 21 feburary 2008. norwegian and russian discourse on the european arcticl.c. jensen & p.w. skedsmo polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 449 http://news.bbc.co.uk http://www.rg.ru/2009/03/30 http://www.regjeringen.no/rpub/nou/20032003/032 http://ec.europa.eu/energy/russia/events/doc http://www.washingtontimes.com/news/2009 http://www.regjeringen.no/upload/kilde http://www.regjeringen morgenthau h.j. 1973. politics among nations: the struggle for power and peace. 5th edn. new york: knopf. neumann i.b. 1994. a region-building approach to northern europe. review of international studies 20, 53–74. neumann i.b. 2001. mening, materialitet, makt: en innføring i diskursanalyse. (meaning, materiality, power: an introduction to discourse analysis.) bergen: fagbokforlaget. norwegian government 2009. nye byggesteiner i nord: neste trinn i regjeringens nordområdestrategi. (new building blocks in the north: the next step in the government’s high north strategy.) accessed on the internet at http://www. regjeringen.no/upload/ud/vedlegg/nordomr%c3% a5dene/byggesteiner_nord.pdf on 27 march 2009. office of the prime minister 2005. the soria moria declaration on international policy. oslo: office of the prime minister. accessed on the internet at http://www.regjeringen.no/en/ dep/smk/documents/reports-and-action-plans/rapporter/ 2005/the-soria-moria-declaration-on-internati.html?id= 438515 on 18 november 2007. parfitt t. 2007. miles below the north pole, russian mini-subs lay claim to arctic wealth. guardian unlimited, 3 august. accessed on the internet at http:// www.guardian.co.uk/world/2007/aug/03/russia.oil on 21 march 2010. parfitt t. 2009. russia plans military force to patrol arctic as “cold rush” intensifies. guardian unlimited, 28 march. accessed on the internet at http://www.guardian.co.uk/ world/2009/mar/28/russia-gas-oil-arctic-nato on 10 april 2009. parker i. 1992. discourse dynamics: critical analysis for social and individual psychology. london: routledge. phillips n. & hardy c. 2002. discourse analysis: investigating processes of social construction. thousand oaks, ca: sage publications. putin v. 2001. annual address to the federal assembly. accessed on the internet at http://kremlin.ru/eng/speeches/2001/ 04/03/0000_type70029type82912_70660.shtml on 17 feburary 2008. putin v. 2002. annual address to the federal assembly. accessed on the internet at http://kremlin.ru/eng/speeches/2002/ 04/18/0000_type70029type82912_70662.shtml on 18 february 2008. putin v. 2003. annual address to the federal assembly. accessed on the internet at http://kremlin.ru/eng/speeches/2003/ 05/16/0000_type70029type82912_44692.shtml on 18 february 2008. putin v. 2004. annual address to the federal assembly. accessed on the internet at http://kremlin.ru/eng/speeches/2004/ 05/26/1309_type70029type82912_71650.shtml on 18 february 2008. putin v. 2005. annual address to the federal assembly. accessed on the internet at http://kremlin.ru/eng/speeches/2005/ 04/25/2031_type70029type82912_87086.shtml on 18 february 2008. putin v. 2006. annual address to the federal assembly. accessed on the internet at http://kremlin.ru/eng/speeches/2006/ 05/10/1823_type70029type82912_105566.shtml on 18 february 2008. putin v. 2007. annual address to the federal assembly. accessed on the internet at http://kremlin.ru/eng/speeches/2007/ 04/26/1209_type70029type82912_125670.shtml on 17 february 2008. putin v. 2008. speech at expanded meeting of the state council on russia’s development strategy through to 2020. accessed on the internet at http://kremlin.ru/eng/speeches/2008/02/08/ 1137_type82912type82913_159643.shtml on 18 february 2008. russian security council 2009a. osnovi gosudarstvennoj politiki rossijskoj federatcii v arktike na period do 2020 goda i dal’nejšuju perspektivu. (principles of the russian federation’s state policy in the arctic in the period to 2020 and in the longer perspective.) security council of the russian federation. accessed on the internet at http://www.scrf.gov.ru/documents/98.html on 12 april 2009. russian security council 2009b. natsional’naia bezopasnost’ rossii: dokumenty, otnociashchiesia k razlichnym aspektam natsional’noj bezopasnosti rossii. (russia’s national security: documents concerning different aspects of russia’s national security.) security council of the russian federation. accessed on the internet at http://www.scrf.gov.ru/ documents/sections/3 on 12 april 2009. schiffrin d., tannen d. & ehernberger hamilton h. 2003. introduction: what is discourse analysis? in d. schiffrin et al. (eds.): the handbook of discourse analysis. pp. 1–10. malden, ma: blackwell. scott j.c. 1998. seeing like a state: how certain schemes to improve the human condition have failed. new haven: yale university press. searle j.r. 1969. speech acts: an essay in the philosophy of language. cambridge: cambridge university press. skagestad o.g. (n.d.) where is the “high north”? the high north—an elastic concept? accessed on the internet at http://www.geopoliticsnorth.org/index.php?option=com_ content&view=article&id=1:an-international-researchproject&catid=1:latest-news&limitstart=1 on 26 march 2010. skedsmo p. 2005. “doing good” in murmansk?: civil society, ideology and everyday practices in a russian environmental ngo. fni-rapport 14/2005. lysaker: fridtjof nansens institute. stokke o.s. & hønneland g. (eds.) 2007. international cooperation and arctic governance: regime effectiveness and northern region building. london: routledge. tonkiss f. 1998. analysing discourse. in c. seale (ed.): researching society and culture. pp. 245–260. london: sage. wæver o. 1995. securitization and desecuritization. in r.d. lipschutz (ed.): on security. pp. 46–86. new york: columbia university press. winther jørgensen m. & phillips l. 1999. diskursanalyse som teori og metode. (discourse analysis as theory and method.) frederiksberg: roskilde universitetsforlag. norwegian and russian discourse on the european arctic l.c. jensen & p.w. skedsmo polar research 29 2010 439–450 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd450 http://www http://www.regjeringen.no/en http://www.guardian.co.uk/world/2007/aug/03/russia.oil http://www.guardian.co.uk/world/2007/aug/03/russia.oil http://www.guardian.co.uk http://kremlin.ru/eng/speeches/2001 http://kremlin.ru/eng/speeches/2002 http://kremlin.ru/eng/speeches/2003 http://kremlin.ru/eng/speeches/2004 http://kremlin.ru/eng/speeches/2005 http://kremlin.ru/eng/speeches/2006 http://kremlin.ru/eng/speeches/2007 http://kremlin.ru/eng/speeches/2008/02/08 http://www.scrf.gov.ru/documents/98.html http://www.scrf.gov.ru http://www.geopoliticsnorth.org/index.php?option=com_ book review book review review of footsteps in the snow, by john dudeney (2022). dunbeath, scotland: whittles publishing. 256 pp. isbn: 978-184995-539-3.   citation: polar research 2023, 42, 9709, http://dx.doi.org/10.33265/polar.v42.9709 copyright: polar research 2023. © 2023 olav orheim. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 03 july 2023 correspondence olav orheim, fram museum, bygdøynesveien 39, no-0286 oslo, norway. e-mail: olav@polarviten.no   as its cover aptly states, footsteps in the snow is the “autobiography of an individual with a remarkable breadth of experience of living and working in antarctica.” after completing university studies, john dudeney joined the british antarctic survey (bas) in 1966; antarctica has been central in his life ever since. he started with a two-year engagement as an ionospheric physicist at an isolated station on the argentine islands, lying just off the antarctic peninsula. during the next four decades he progressed to leader of the geospace group and finally to deputy director. nine-tenths of the book cover this period. dudeney describes an institution undergoing large changes. having known bas as a first-class polar research and logistic organization—the british counterpart of the norwegian institute that i led through major transformations—i was surprised to read so much about personel conflicts. presumably this reflects the author’s aim to write a frank autobiography, warts and all. during his four decades at bas, dudeney did not always advance as rapidly as he felt he deserved, a complaint that turns up several times. he was constantly travelling to antarctica, and comes across as bas’ chief troubleshooter. this is not a trivial position! an autobiography should rightly focus on the author, so dudeney may be forgiven for occasionally giving an exaggerated impression of his personal impact to readers who come to the book with little prior knowledge of the larger context. there are relatively few references to his superiors regarding issues that i imagine must have been decided at the top of the organization. instead, the narrative often suggests that dudeney was the main planner and decision-maker. examples include personnel problems at halley station and many challenges related to rebuilding the station, and, at rothera station, handling the fire and, later, the fatal diving accident. during his final six years at bas, he was involved with antarctic politics (with perhaps a less prominent role than the narrative suggests), working on the liability annex to the environmental protocol and on the report of the antarctic treaty consultative meeting in edinburgh in 2005. judging by the profusion of details, dudeney must have a prodigious memory and been an assiduous diary-keeper. footsteps in the snow should be of interest to readers who want to know more about dudeney, those who worked at bas during his years there, and everyone concerned with upper-atmospheric research in antarctica. the book neither provides general information about antarctica nor discusses issues such as climate change and sea-level rise, which are now of public interest. i wouldn’t recommend the book for readers looking for general information about antarctica or for stunning images. since retiring, dudeney has spent many seasons lecturing aboard antarctic tourist cruise vessels. with his breadth of experience, he must be a welcome addition to the expedition teams on these ships. he and john sheail have also undertaken very interesting historical research through extensive archive-digging. this has produced peer-reviewed articles on early british antarctic policy and about ernest shackleton declining help to rescue his party on elephant island—ample demonstration of his continued engagement in antarctic issues and his lively mind. near the end of his autobiography, he states that he is collaborating with colleagues on a new book examining britain’s role in the southern ocean whaling industry. i am sure this will also bring to light new fascinating information. no job name r e s e a r c h n o t e further to the death of sigurd b. myhre at camp abruzzi, rudolf island, franz josef land, during the ziegler polar expedition, 16 may 1904por_089 463..467 p.j. capelotti division of social sciences, penn state abington, abington, pa 09001, usa abstract in the spring of 1904, during the ziegler polar expedition led by anthony fiala, sigurd b. myhre, a norwegian from trondheim who served on-board the expedition ship america as a fireman, fell ill and died. the papers of dr george shorkley, surgeon to the ziegler polar expedition, contain hints that myhre may have died from causes other than natural causes. keywords anthony fiala; franz josef land; george shorkley; sigurd myhre; teplitz bay; ziegler polar expedition. correspondence p.j. capelotti, division of social sciences, penn state abington, abington, pa 09001, usa. e-mail: pjc12@psu.edu doi:10.1111/j.1751-8369.2008.00089.x by may 1904, the ziegler polar expedition had suffered a series of misfortunes at camp abruzzi, its base on the northern edge of teplitz bay on rudolf island in franz josef land (fig. 1). the spectacularly well-funded, and hence well-equipped, expedition was provided with further supplies that had been left behind on rudolf island by the polar expedition of the duke of the abruzzi, in 1900, and by the baldwin–ziegler polar expedition, in 1902. however, by april 1904 fiala had managed to squander much of this vast quantity of material. even before the expedition base camp was established, he had lost nearly a quarter of the ponies he was to use for the polar dash to disease and careless handling. five per cent of his 218 dogs were lost, along with the ship’s dinghy, after they were left on the teplitz bay ice and carried away as a gale sprang up. the ship itself—the america—was crushed by pressure ridges of ice in teplitz bay in november 1903, and disappeared in a storm two months later, either sinking at its mooring or being simply blown out to sea. twentythree sailors who had been living on-board the ship were now forced into the shore hut, alongside 16 already overcrowded scientists, surveyors and surgeons. the grumbling of the crew, who had accompanied the expedition on the voyage through the ice, south of franz josef land, through the british channel to rudolf island, hardened to dissension with fiala’s leadership. dissension, failure, injury and revolt on 7 march 1904, fiala made the first of three attempts to reach the pole. he took 26 men, 16 ponies and 117 dogs north-east to cape fligely, where he planned to descend onto the sea ice and sledge north. at cape fligely, five men could not proceed. these included the norwegian sigurd b. myhre, with an unspecified ailment, and charles e. rilliet, an engineer from st. louis, missouri, who had been instrumental in launching a series of balloons from alger island during the baldwin–ziegler expedition in june 1902 (capelotti 2008). rilliet had suffered a hernia pulling one of the sledges across the rudolf island ice dome. fiala, blaming his failure on the bad condition of his men, retreated to camp abruzzi after just four days. when a second attempt, on 25 march 1904, only managed to proceed three kilometres on the sea ice north of cape fligely, with fiala retreating after just two days in the field, dissension erupted into open revolt. at camp abruzzi, the expedition now broke down into a variety of cliques, with no real central authority, so when fiala called for men to remain on rudolf island for another try at the pole in 1905, there were few volunteers. as fiala admitted, “the men lost interest in the northern campaign and openly expressed their deep felt desire to go home” (fiala 1906: 88). faced with a disintegrating situation, fiala led a retreat to cape flora on polar research 28 2008 463–467 © 2008 the author 463 mailto:pjc12@psu.edu northbrook island with 25 of the 39 members of the expedition. there, fiala expected a relief ship to arrive that summer and take his disheartened crew home, prior to fiala making another attempt on the pole in 1905. those who left rudolf island included all of the expedition’s medical personnel: doctors george shorkley and charles l. seitz; medical student j. colin vaughn; and veterinarian h.h. newcomb. those who remained behind at camp abruzzi included the chief scientist of the expedition, william j. peters, and his two assistants, russell w. porter and r.r. tafel; the chief engineer of the ship, henry p. hartt; the assistant commissary, spencer w. stewart; the steward, bernard e. spencer; three sailors from massachusetts, william r. myers, d.s. mackiernan and elijah perry; two swedes, john and anton vedoe; two norwegians, myhre and the carpenter peter l. tessem; and, finally, rilliet (fiala 1906: 12–14; vedoe 1992: 115–116; fig. 2). brief notes on the last months of sigurd myhre the first suggestion that something was wrong with sigurd myhre comes in the medical journal kept by george shorkley (shorkley 1903/04). from the start of fig. 1 franz josef land, showing the locations of cape flora, teplitz bay and cape fligely (after barr 1995). fig. 2 sigurd myhre (left), pictured along with other members of fiala’s crew at teplitz bay in the winter of 1903–04. the men are sewing fur clothing. in this image, myhre is working away, contrary to notes written about him before and after his death. (courtesy of the norwegian polar institute photo library. a cropped version of this photograph was published in fiala [1906], between p. 72 and p. 73.) further to the death of sigurd b. myhre p.j. capelotti polar research 28 2008 463–467 © 2008 the author464 the expedition, shorkley had kept a close eye on the health of each and every crew member. for example, he had very quickly diagnosed fiala with a severe nervous condition that caused disorientation, bordering on madness (shorkley 1903/04: 15 august 1903), and had also diagnosed captain edwin coffin, the master of the america, with extreme alcoholism (shorkley 1903/04: 23 august 1903). shorkley’s journal mentions myhre in several places. on the initial journey from norway to franz josef land, shorkley had examined each member of the crew, save coffin and his first officer edward haven, both of whom refused to submit to physical examination. myhre’s examination elicited the following details: he was 29 years old, stood 5 feet 6 inches (168 cm) tall and weighed 155 pounds (70 kg). he had been born in trondheim, norway, and had a tattoo of an “indian girl” on his right forearm and the initials “s.m.” on his left hand. his teeth were in very poor condition, with two upper and two lower molars missing on each side of his mouth. when shorkley weighed the crew later in the fall, myhre had put on seven pounds, weighing in at 162 pounds (73 kg). on 10 november 1903, shorkley wrote that he had gone from the base camp out to the ship to see hartt, who was ill with an incapacitating rectal inflammation, and myhre. he wrote “[myhre] is a case of malingery [sic]” (shorkley 1903/04). since the summer, shorkley had noted several crew members that he believed were shirking their work, and from this note he clearly felt myhre was one of them. on march 8, shorkley recorded what happened to myhre on the march to cape fligely: the norwegian had stabbed his own hand while trying to cut a piece of pemmican. shorkley and the rest of his medical staff left camp abruzzi on 1 may 1904. on 5 may 1904, anton vedoe wrote in his diary that “tessem and myhre have been sick. most likely a bad touch of cold. they have been in bed most of the time and feel quite feeble. i have had a slight cold but not to interfere with my work” (vedoe 1992: 116). four days later, anton vedoe left camp on a surveying journey south, via austria sound, with porter, rilliet, mackiernan and spencer. peters, tafel and john vedoe would journey south to cape flora via the british channel later in the summer. anton vedoe and his party reached cape flora in mid-july, whereas peters and his team did not reach cape flora until 31 august. they brought the news that myhre had died on 16 may (vedoe 1992: 137). fiala wrote briefly in his official account of the expedition that myhre “died at camp abruzzi on may 16th after an illness of several weeks” (fiala 1906: 121). the expedition buried myhre four days later, on 20 may, under a pile of rocks at cape saulen, just north of teplitz bay. fiala described his gravesite as “the most northern tomb, i believe, in the world” (fiala 1906: 121). a photograph (fig. 3) from fiala’s account shows a carefully crafted and erected cross marking myhre’s grave, which overlooks the arctic sea. barr (1991) was shown the remnants of this cross when she visited the nearby meteorological station at teplitz bay in 1991. porter, who, by the end of the summer of 1904, was having serious doubts about whether any of them would survive, mentioned the death in his diary. . . . [the] person was one murray [sic], a norwegian fireman, who passed away at camp abruzzi, on 16 may, with no medical aid at hand (all the physicians had come south to go home). score one against this expedition for the evil spirit hovering forever over the arctic waste. may it be the last although i doubt it. this man was ill when i was there the first of may and i understand he never recovered, was unconscious a good deal of the time and would not answer when spoken to. he leaves a wife in bergen. (porter no date: 50) (fiala [1906: 195] wrote that when the expedition was rescued by the ship terra nova in mid-summer 1905, “great bags of mail” arrived with the ship, including one letter addressed to myhre, who had already been dead for over a year. it related the news that myhre’s wife in norway had died. one account relates the extreme coincidence that husband and wife had passed away on the very same day.) shorkley, in overall charge of the health of the expedition, questioned the peters group closely about what had happened to myhre. written beneath his notes on myhre’s physical examination, shorkley added the following. fig. 3 the grave of sigurd b. myhre, cape saulen, rudolf island, franz josef land (from fiala 1906). further to the death of sigurd b. myhrep.j. capelotti polar research 28 2008 463–467 © 2008 the author 465 party arriving at cape flora from camp abruzzi report the death of myhre, at the latter place, on the 16th of may 1904. cause of death unknown. the only significant symptoms available are that, during the last few days of his life, deceased was in a state of extreme cyanosis & of stupor amounting almost to complete coma. buried in a cairn of rocks on the hill just nw of the camp, the cairn being marked by a wooden cross about 6 ft. (183 cm) in height, upon which is carved a suitable inscription. (shorkley 1903/04: undated entry, probably 31 august 1904) shorkley’s doubts and hartt’s letter when ice prevented the expected relief ship from reaching franz josef land in 1904, the expedition, riven by dissension, crippled by short rations and scattered in several groups around franz josef land, descended into depression. shorkley’s medical journal soon diminished to barely a single line each day, and then ceased altogether on 7 september 1904. somehow, the men all survived the second winter. fiala attempted his third, final and equally brief attempt on the pole on 16 march 1905. the following day, porter arrived at camp abruzzi from cape flora, and brought a letter to hartt from shorkley. shorkley must have heard or been told by someone in the peters party at cape flora that rilliet had given some medications to myhre before he died, and shorkley wanted to know just what those medicines had been. in reply, hartt wrote a long, tortuous letter describing his own rectal surgery at the hands of seitz, who had returned to camp abruzzi the previous fall. hartt additionally suffered from a sprained ankle, a sprained knee and a broken rib. he had all but given up hope of seeing civilization again. then, in answer to shorkley’s query about myhre, hartt wrote the following. you were asking me to try and remember the kind of medicine that rilliet, gave murry [myhre]. i could not say what he gave him, i only heard him make the remark before he left here that he had given him enough medicine to kill two men. i suppose though he was fooling at the time he made the remark, because he thought as every one else did i suppose, murry, was playing another one of his tricks to get out of work. (hartt 1905) from this note it is impossible to identify which substances rilliet might have given to myhre, or whether he had received any further medication after rilliet left camp abruzzi, on 9 may, with porter’s exploring party. at that time, nine men, including myhre, were left at camp abruzzi. these included hartt, the peters party, of peters, tafel and john vedoe (who would leave after myhre died and bring the news of his death to cape flora), along with sailors gustave meyer and elijah perry, assistant commissary spencer stewart, and carpenter peter tessem. anton vedoe, as quoted earlier, merely thought both myhre and tessem were suffering from bad colds. he certainly gives no hint that he thought that myhre was near death. tessem soon recovered from his “bad cold”, but myhre worsened and soon died. if the two events are connected, did rilliet give a bigger dose of medicine to myhre than to tessem simply because he thought he was shirking his workload? shorkley’s list of medical supplies left behind at camp abruzzi—when the larger part of the expedition retreated in may 1904—includes enough to supply a small hospital, including over 30 000 pills of various types. a sense of what would have been included comes from shorkley’s medical journal entry of 13 july 1903, when fiala asked shorkley to prepare a package of medical supplies that would be left in a box at cape flora in case of emergency. these include morphine, laxatives, diarrhea tablets, and medicines for coughs and headaches. conclusions: suicide, illness or murder? the comments made by both shorkley and rilliet about myhre’s avoidance of work cast an interesting light on his hand injury at cape fligely. was the stab wound in fact accidental, or had myhre—like fiala himself, for that matter—looked out over the implacable polar sea from the heights of cape fligely, and searched for a way out of what was clearly a doomed expedition? by the time they reached cape fligely, shorkley was already convinced that fiala was incompetent, if not outright mad. if myhre had come to the same conclusion, then a cut on the hand was preferable to being led across a thousand miles of polar ice by a hopeless commander. such an action would suggest a strong impulse for self-preservation, which would seem to rule out the notion that myhre might have killed himself through an overdose once safely back at camp abruzzi. shorkley’s long-distance diagnosis of extreme cyanosis could have been the result of hypothermia, but could also have resulted from any number of other causes, including myocardial infarction or heart attack. the additional condition of stupor further suggests hypothermia. during a winter when the temperatures at camp abruzzi fell below –40°c, it is possible that myhre was literally freezing to death. the possibility that myhre was suffering from the end stages of some other undiagnosed terminal illness cannot further to the death of sigurd b. myhre p.j. capelotti polar research 28 2008 463–467 © 2008 the author466 be discounted, but this possibility seems unlikely to have escaped the notice of shorkley. furthermore, the symptoms, such as were gathered by shorkley, do not suggest any of the more common afflictions suffered by polar explorers of this and other eras. scurvy is discounted for several reasons. the expedition’s table was well supplied in its first months, and the disease would have produced bleeding and anaemia, neither of which was recorded for myhre. the boiled stews and processed foods eaten by the expedition, combined with the length of time myhre seemed to suffer, argue against the more rapidly moving trichinosis, which apparently caused the demise of andrée and his men seven years earlier. fever and coughing, two symptoms of tuberculosis, do not seem to have been present in myrhe, and, of course, the great influenza epidemic that indeed reached the arctic was still 14 years away. rilliet would have made his comment about giving myhre enough medicine to kill two men both before he left camp abruzzi and before myhre died. we have a sense of how he reacted when the peters party arrived at cape flora just after midnight on 1 september 1904, bringing with them the news of myhre’s death. most of the camp was asleep, except for rilliet and anton vedoe, who were pottering about in their own small hut. john vedoe, whose diary of the trip south to cape flora is embedded in his brother’s account of the expedition, writes that “the sad news of myhre’s death brought seriousness to the otherwise happy faces . . .” (vedoe 1992: 212). if rilliet had indeed made light to hartt that he had overmedicated myhre, the realization that myhre was dead and that he might be the cause must have come as a tremendous shock. anton vedoe, tessem and rilliet all returned to camp abruzzi at the end of june 1905, to make a last visit before retreating south. they remained in the otherwise empty camp for a week. vedoe spent the time taking photographs and cleaning the expedition hut. he makes no mention of what rilliet did during this time, and there is no indication that any of them hiked to cape saulen to visit myhre’s grave. on 2 july 1905 they nailed the expedition hut closed, and the last three representatives of this “american” expedition—a norwegian, a swede and an american—left rudolf island for the final time. what can be said for certain in this strange tale is that sigurd myhre died on 16 may 1904, after suffering for more than a week with an extreme form of cyanosis, accompanied by near-coma, while his fellow countryman, tessem, recovered from his illness. if, as hartt suggests, rilliet really thought that myhre was shirking his workload, and proceeded to medicate him to the point of overdose, his actions contributed to, if not caused, myrhe’s death. such an event further complicates a chapter in the history of an expedition that is already replete with examples of human weakness. references barr s. 1991. soviet–norwegian historical expedition to zemlya frantsa-iosifa. polar record 27, 297–302. barr s. 1995. franz josef land. oslo: norwegian polar institute. capelotti p.j. 2008. a “radically new method”: balloon buoy communications of the baldwin–ziegler polar expedition, franz josef land, june 1902. polar research 27, 52–72. fiala a. 1906. fighting the polar ice. new york: doubleday, page & company. hartt h.p. 1905. letter to george shorkley, 21 march 1905. the papers of george shorkley (1871–1945), rauner special collections library, stefánsson manuscripts no. 207, dartmouth college, hanover, nh, usa. porter r.w. no date. arctic fever. unpublished manuscript. the papers of russell w. porter (1871–1949), rauner special collections library, stefánsson manuscripts no. 118, dartmouth college, hanover, nh, usa. shorkley g. 1903/04. medical records—ziegler polar expedition, june 22, 1903–september 7, 1904. the papers of george shorkley (1871–1945), rauner special collections library, stefánsson manuscripts no. 207, dartmouth college, hanover, nh, usa. vedoe a. 1992. the arctic diary of anton m. vedoe. unpublished, revised february 1992. the papers of anton m. vedoe (1880–1942), rauner special collections library, stefánsson manuscripts no. 233, dartmouth college, hanover, nh, usa. further to the death of sigurd b. myhrep.j. capelotti polar research 28 2008 463–467 © 2008 the author 467 priestley’s progress: the life of sir raymond priestley, antarctic explorer, scientist, soldier, academician book review priestley’s progress: the life of sir raymond priestley, antarctic explorer, scientist, soldier, academician, by mike bullock, jefferson, nc: mcfarland, 2017, 197 pp., £38.95 (paperback), isbn 978-0-78647805-7 raymond priestley was a key figure in the “heroic age” of antarctic exploration who travelled south with both scott and shackleton. after serving in the first world war, he played a role in the early years of the scott polar research institute at cambridge, and later in life his administrative talents were turned to acting leadership of the falkland islands dependencies survey (fids)—the forerunner of today’s british antarctic survey. in between he found time to serve as vice-chancellor of first melbourne and then birmingham university. mike bullock argues that this long and diverse career warrants a dedicated biography. this is a sentiment that i heartily agree with, even if this particular book cannot be regarded as the definitive scholarly work on priestley. the key source of information is priestley’s extensive unpublished diaries. bullock is right to point to them as an important and underused historical resource. from these emerge a picture of a diligent, proper and, above all, very english individual. comments on cricket and the church pepper the text. bullock clearly has great admiration for his subject, and sympathy for his world view, including a wry sense of humour capable of making light of even the most difficult situations. readers of polar research may be disappointed at the comparatively brief account of priestley’s remarkable (and justly famous) participation in the northern party of scott’s final expedition. seen in the context of the book as a whole, however, the choice makes sense: bullock is primarily concerned with showing the full spectrum of activities that made up priestley’s rich life, beyond the one episode for which he was arguably best known. bullock’s meticulous use of priestley’s diaries produces a sharp portrait of their author and his sensibilities. this is particularly true of his later years, when priestley moved in the upper levels of society and became a living icon of britain’s antarctic heritage. his participation in the antarctic cruise of the royal yacht britannia in the company of prince philip clearly made a great impression. but the wealth of detail on protocol and life aboard ship may try the patience of some readers, particularly as there is comparatively little detail on priestley’s time at fids. nor does bullock make much reference to the relevant scholarly literature concerning this period. considerably more remains to be said about the great institutional changes in british polar research that took place during that long and interesting life, and about the specific contributions that priestley made to the development of geological knowledge of the antarctic continent. a rich field remains for historians and scholars of polar research. peder roberts division of history of science, technology and environment, kth royal institute of technology, stockholm, sweden, peder.roberts@abe.kth.se © 2018 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://crea tivecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. https://doi.org/10.1080/17518369.2018.1477204 polar research 2018, vol. 37, 1477204 http://www.tandfonline.com http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2018.1477204&domain=pdf http://www.tandfonline.com book review por_014.fm polar research 26 2007 205 – 206 © 2007 the author 205 b o o k r e v i e w review of scott’s last biscuit: the literature of polar exploration , by sarah moss (2006). oxford: signal books. 251 pp. isbn 1-902669-87-8. fifty years ago, george bass revolutionized maritime archaeology with the observation that it was far simpler to train an archaeologist to be a scuba diver than it was to turn a scuba diver into an underwater archaeologist. one is tempted to make a similar observation about literary theorists writing polar history while reading this interesting volume. it is not that scuba divers cannot perform underwater archaeology; it is just that one set of skills cannot be learned nearly as quickly as the other. as a literary theorist, moss, a lecturer in english at the university of kent, canterbury, uk, alternates between the best and a bit of the worst of postmodern feminist literary analysis in this intensely interesting series of essays on the fiction, non-fiction and poetry of polar exploration. the focus here is on the polar regions as places of continuous disorientation, where there is only one day and one night per year, and where one can walk forwards and backwards at the same time. the arctic and antarctic are unstable places not only climatically, navigationally and cartographically but, as this study suggests, as templates for human longing and desire, heroism and the projection of cultural superiority. for the most part the book works remarkably well as literary analysis, especially the fascinating trope on the norse greenlanders as the original arctic explorers (except that, as usual, the celts beat them to it nearly everywhere). one learns of the remarkable notion that hans egede died still convinced that an idyllic eastern settlement lay just on the other side of greenland, rather than directly under his feet in the form of archaeological remains. moss offers a plausible suggestion for why the western settlement was found eerily and very recently abandoned in 1350 (resulting from the natural aversion to anyone on the horizon who looked like a tax collector), but her suggestion that the colony was still a going concern as late at 1605 (p. 40) is arguable at best. at that point, no one had heard from the greenland vikings for nearly 200 years. to her credit, moss admits that the disappearance of the norse greenlanders is still a mystery waiting to be solved; in my opinion by maritime archaeology. the segment on the modern viking fridtjof nansen is similarly excellent, save for a slight bump into a feminist hummock that conflates nansen’s hunting of baby bears with anxieties over “feminine softness and overindulgence on the fram …” (p. 81). unfortunately, many of the essays that follow are marred by factual errors that threaten to sink the whole effort (and would do so if they did not similarly freight so many other works on polar exploration). these omissions and errors appear when moss retells history to support her criticism of the literature of that history. some of these are minor or apparent slips of the pen: john cabot is nowhere to be found; poul norlund becomes paul norlund; svalbard is referred to as “spitzbergen”, which in itself is a corruption of “spitsbergen”. (as one of the first people i met in longyearbyen remarked: “it has an ‘s’ instead of a ‘z’ because it was discovered by a dutchman and not a german”.) ernest h. correspondence p. j. capelotti abington college, penn state university, abington, pa 19001, usa. e-mail: pjc12@psu.edu 206 polar research 26 2007 205 – 206 © 2007 the author book review shackleton had returned to antarctica once, on nimrod , between the rss discovery and endurance expeditions, not “several times” (p. 21). moss’ arctic history is perhaps too credulous when discussing robert e. peary’s claim to the north pole; perhaps too incredulous when dismissing the great united states exploring expedition under charles wilkes. scientists experimented with aviation at the poles both before and after the first world war, but not after the second world war (p. 23), by which time aviation was a given in polar operations. thoreau’s walden pond (p. 86) is in massachusetts, not in maine. then there are the errors that seem to compound each other. by now, it seems clear that parliament should proclaim that no british polar scholar shall henceforth cite roland huntford’s the last place on earth on captain robert f. scott without first proving that they have studied sir ranulph fiennes’ counterbalancing captain scott . scott is described as choosing polar exploration because it still held the prospect of rapid promotion “two hundred years after parry’s voyages” (p. 99), which should, of course, be less than 75 years after parry’s voyages. scott is described incorrectly as being forced from the bay of whales (p. 100) after finding captain roald amundsen and fram already there, when the two never met (although, as fiennes relates, not for want of scott’s trying, especially when amundsen hid himself during scott’s pre-expedition visit to oslo). moss parrots the manifestly incorrect claim that scott “refus[ed] to take any notice of scandinavian and american success with skis and dogs” (p. 101) when he took not only dogs and skis, but also ponies and motor-sledges (and, earlier, a balloon) to antarctica. apsley cherrygarrard (p. 115) takes his famous winter journey to the penguin rookery with lawrence e. g. “titus” oates and dr edward adrian “uncle bill” wilson, when it was, of course, wilson and henry robertson “birdie” bowers along with “cherry” who survived that intense ordeal conducted for pure science. there are similar problems with the chapter on the swedish aeronaut salomon august andrée. the reader is led to believe that andrée sought to reach the north pole in a hot air balloon, when his whole aeronautical career was centred on adapting hydrogen gas balloons for geographic exploration. moss congratulates andrée on his brave use of new technologies, a notion she does not impart to the lamented captain scott. knut fraenkel is described as a railway engineer “much younger than the other two [crew members]” (p. 117), when in fact he was just out of civil engineering school and two years older than the youngest expedition member, the tragic lover/ photographer nils strindberg (whose intense love affair with anna charlier is glossed over in this book that does so much elsewhere to explore the role of women in the polar regions). moss concludes her analysis of the failure of the expedition with the remarkable assertion that the men died because they were cold and had no winter clothing, even though they had survived several hundred kilometres of a frigid trudge across the ice pack to kvitøya, and presumably were all dead long before the onset of the winter of 1897. the bibliography suggests that moss has not read anything on the subject published after 1931. despite these errors—and they are maddening—this book reveals a potential polar essayist of some stature. there are really several potential books here, not least the still-unwritten cultural comparison between the explorers of scandinavia and those of the uk and the usa. but like george bass’ scuba diver trying to learn archaeology, moss needs to show that she can master the details of polar expedition history before attempting to survey the whole shipwreck. for now, scott’s last biscuit works well as humanism and literary criticism, less so as humanism and polar history. references fiennes r. 2003. captain scott . london: coronet books. huntford r. 1999. the last place on earth . new york: modern library. no job name from the editor: halfway through the ipy—halfway for an antarctic traverse doi:10.1111/j.1751-8369.2008.00048.x april is here and we have just passed the midpoint of the international polar year (ipy), which began on 1 march 2007 and will conclude on 1 march 2009. the “year” stretches over 24 months to accommodate two summer field seasons in both polar regions. the northern summer is fast approaching, and scientists who will undertake a second ipy summer season in the arctic are making their final preparations. at the opposite end of the planet, summer is over and scientists have wrapped up the first ipy field season. those whose projects will carry on for a second summer season will have to wait until late this year to resume work in antarctica. one ipy project that is making full use of both antarctic summers is the norwegian–us scientific traverse of east antarctica (http://traverse.npolar.no/). this joint project is part of the larger trans-antarctic scientific traverses expeditions—ice divide of east antarctica (taste-idea) and the international partners in ice coring sciences (ipics). these two international consortia involve a number of coordinated traverses across antarctica during the ipy. norway–usa, sweden–japan, germany, france– italy–russia, china, australia and the usa are responsible for the traverses, which criss-cross east antarctica from starting points that include taylor dome, talos dome, wasa station, neumeyer station, troll station, syowa station and zhong shan station. the expeditions are travelling through some largely unexplored areas of antarctica. along the route, scientists and technicians extract ice cores, make detailed meteorological observations, measure ice depth, investigate ice dynamics, survey under-ice geology and deploy instruments that will continue to furnish data after the ipy is over. it is anticipated that the data amassed during these traverses—as well as those that will continue to come in, post-ipy, from automatic weather stations and snow accumulation stakes, for example—will significantly improve our understanding of past, current and future climate variability, cryosphere–atmosphere interactions and antarctic ice mass balance. two-thirds of all the planet’s freshwater—including lakes, rivers, groundwater, glaciers and moisture in the atmosphere—exists as ice in antarctica. the deepest ice measured in antarctica so far is 4776 m thick; the average antarctic ice thickness is about 2000 m. large parts of the continent are inadequately mapped with respect to ice thickness. measuring ice thickness during the traverses will clarify the picture, rough sketch of the international polar year (ipy) traverses of antarctica under the umbrella of the trans-antarctic scientific traverses expeditions—ice divide of east antarctica. actual routes may differ from those shown here. (illustration based on a diagram at http:// www.ipy.org/index.php?ipy/detail/taste_idea/, accessed on 18 january 2008.) wasa station kohnen station troll station syowa station mizuho zhong shan station dome a dome b dome c vostok talos dome south pole dome fuji plateau station pole of inaccessibility taylor dome neumeyer station norway–us japan–sweden china us germany france–italy–russia australia polar research 27 2008 1–6 © 2008 the author 1 http://traverse.npolar.no http://www.ipy.org/index.php?ipy/detail/taste_idea http://www.ipy.org/index.php?ipy/detail/taste_idea the route of the norwegian–us scientific traverse of east antarctica. in january 2008, the expedition was forced to conclude about 350-km short of the south pole. the return leg, which will take place in the coming austral summer, will start from this point, will continue to the south pole and will then take the expedition on to troll station. from the editor polar research 27 2008 1–6 © 2008 the author2 and will help answer such crucial questions as what is the contribution of antarctica’s ice to sea level change. led by norwegian polar institute director jan-gunnar winther, the norwegian–us scientific traverse of east antarctica is norway’s contribution to taste-idea. the norwegian–us traverse is being undertaken in two stages. the first was planned to have taken the expedition from the norwegian troll station to the us amundsen– scott south pole station in the austral summer of 2007/ 08. the second stage was intended to start from the south pole and return to troll station, by a different, shorter route, during the following summer. in a region as challenging to work in as antarctica, it is perhaps no wonder that the first leg of the traveser did not go precisely to plan. after a delay caused by some days of very high winds—gusts peaking at 185 km h-1 capsized 20and 40-ft containers, and caused other equipment to vanish completely—the team set out from troll station on 16 november 2007. the expedition travelled in four tracked vehicles hauling sleds. as expected, heavy loads and the high-altitude thin air made the going slow. the expedition made numerous planned stops to collect fuel and carry out scientific work. extracting ice cores turned out to be difficult at sites where meagre annual snowfall and annual mean temperatures of around –55°c made the ice fragile, particularly close to the surface. it tended to crumble when disturbed, leaving breaks and gaps in the core, unless handled with great care. in late november, cameraman art howard, who represented polarpalooza, an ipy outreach programme dedicated to science education, fell ill with a stomach ailment. he was airlifted back to troll station; the filming for polarpalooza podcasts of the expedition was taken over by other expedition members. in december, the medical doctor at troll flew out to the expedition to treat lou albershardt, who had wounded her finger. the greatest challenge proved to be keeping the vehicles in working order despite the harsh environmental conditions and the very heavy demands placed on them as tonnes of ice cores were added to the load during the progress of the expedition. there were numerous delays as the mechanics grappled—typically in extremely cold temperatures—with difficulties with the tracked vehicles. the differentials and transfer cases were particularly troublesome. these broke down repeatedly and new ones were flown in. some of the participants of the 2007/08 norwegian–us traverse posing for a group picture at troll station. left to right: einar johansen (norwegian polar institute [npi]), atsuhiro muto (university of colorado), stein tronstad (npi), glen liston (colorado state university), stian solbø (northern research institute tromsø), john guldahl (npi), jan-gunnar winther (npi), tom neumann (university of vermont), mary albert (dartmouth college), kjetil bakkland (npi), helgard anschütz (npi), lou albershardt (university of wisconsin) and karsten müller (university of oslo). (photo by leif morten tangen; courtesy of norwegian polar institute photo library.) the four tracked vehicles each pulled two sleds loaded with fuel, equipment, and living and working quarters. (top photo by atsuhiro muto. bottom photo by stein tronstad; courtesy of norwegian polar institute photo library.) from the editor polar research 27 2008 1–6 © 2008 the author 3 ultimately, the mechanical problems proved insurmountable despite the tireless efforts of the mechanics. about 350 km short of the intended finishing point for the first leg of the traverse—the south pole—the last of the replacement parts available from the manufacturer failed, bringing the expedition to a final standstill in mid-january. the vehicles and hardier equipment and supplies were battoned down for the winter. personnel, scientific samples and gear unlikely to withstand the antarctic winter were taken by air to the amundsen–scott south pole station, and thence back to civilization. just before departing for the south pole, the leader of the expedition reflected, “it has been a long journey and it will be good to complete it. however, it is with mixed feelings we are leaving behind the breathtaking wonders of antarctica. we had a fantastic time on the ice. we leave with good memories, new friends and . . . will be back!” crevasse-detecting radar developed by the norwegian polar institute. mounted in a 12-m forward boom in front of the lead vehicle, the device allows the driver to monitor the structure of the ice down to 30 m below the surface, and thereby to avoid crevasses. (photo by jan-gunnar winther; courtesy of norwegian polar institute photo library.) the expedition stopped at various points along the route to pick up barrels of fuel that had been cached during the preceding antarctic summer in preparation for the international polar year traverse. here karsten müller stands by a partly excavated depot. (photo by stian solbø.) jan-gunnar winther (right) and tom neumann (left) drill a 12-m ice core with a hand auger at one stop along the way. ice cores contain valuable information about the climate of the past. (photo by atsuhiro muto.) mary albert taking samples in a snow pit. the samples will be examined for black carbon, which originates in the industrialized regions of the world and is transported by the atmosphere to antarctica. black carbon reduces the extent to which snow reflects solar radiation and increases the amount of solar energy snow absorbs, and is therefore an important consideration in climate studies. (photo by jan-gunnar winther; courtesy of norwegian polar institute photo library.) from the editor polar research 27 2008 1–6 © 2008 the author4 though naturally disappointed in not making it all the way to the south pole with the tracked vehicles, the team was aware that the planned scientific work had been carried out. in this most important respect the expedition was a great success. working under extreme conditions that often included temperatures well below –40°c and low levels of oxygen, on account of the thin polar atmosphere and the high elevation, they had collected over 700 m—amounting to 5 tonnes—of ice cores, and had collected a range of important measurements and observations in this poorly known part of the world. the next stage of the norwegian–us scientific traverse of east antarctica will begin this coming november, setting out from the point at which the first leg was forced to stop. this will take the expedition to the south pole and back to troll station. the route passes over three of four newly discovered subglacial lakes, identified using satellite imagery and ice-surface elevations (bell et al. 2007; kohler 2007). more than 150 subglacial lakes are known to lie beneath the vast antarctic ice sheet. the most recent discoveries are located just at the start of an area of rapid ice flow in the recovery glacier ice stream. this suggests that the lakes have something to do with the rapid movement of ice in glaciers such as this one. data collected during the norwegian–us traverse of 2008/09 will help elucidate the important role that subglacial lakes may play in ice-sheet mass balance. the two-stage norwegian–us scientific traverse of east antarctica is the most ambitious expedition undertaken by norway since the international geophysical year, 50 years ago. the nation has a notable history of lou albershardt, the expedition’s chief driller, extracting an ice core from a 90-m hole. (photo by stein tronstad, courtesy of norwegian polar institute photo library.) stian solbø sets up the expedition’s first automatic weather station, which was prepared by the ice and climate group at the university of utrecht. the station will send meteorological data for the next five years via satellite. (photo by jan-gunnar winther; courtesy of norwegian polar institute photo library.) the expedition stopped at plateau station, last occupied by us scientists in 1969. the tall meteorological tower and some smaller towers are still standing. the clear dome of the aurora tower and the top of a smokestack of the old main station are visible just above snow level. the norwegian–us team entered through a hatch and found the buried station to be a time capsule of the late 1960s. (photo by stein tronstad; courtesy of norwegian polar institute photo library.) from the editor polar research 27 2008 1–6 © 2008 the author 5 exploration in the arctic and antarctic; indeed, the south pole was first attained by norwegian roald amundsen’s five-man team in 1911. norway has participated strongly in every ipy since the inception of this international scientific endeavour in the late 19th century (bones 2007; goldman 2007). the last page of this issue offers a glimpse of what conditions were like for the norwegian team overwintering at norway station, antarctica, during the international geophysical year, otherwise known as the third ipy. working and living conditions in antarctica have certainly improved since then—the newly rebuilt amundsen–scott south pole station boasts modern medical and dental facilities, a greenhouse, post office, games room, gym and many other features. as life in antarctica has become safer and more comforatble, the expectations we have of the technicians and scientists who carry out research in antarctica have risen commensurately. these men and women bear an enormous responsibility. the extent to which the climate is changing and has changed in the past and how current and future climate change will alter other aspects of the global natural system are widely recognized as ranking among the most important questions of our time. (in recognition of how these changes may have profound consequences for human society’s welfare and security the 2007 nobel peace prize was awarded to the intergovernmental panel on climate change and al gore.) climate and related environmental questions can only be answered by concerted international scientific research of the kind being carried out during this ipy at the cold ends of the earth on an unprecedented scale. as a final note, i have the pleasure of announcing the establishment of polar research’s editorial advisory panel. along with the other members of the editorial board, i welcome the participation of our new editorial advisers, who are listed inside the front cover of this issue. providing scientific expertise that complements that of the journal’s subject editors, and bringing potentially important manuscripts to our attention, the editorial advisers serve a vital supporting role for polar research. helle v. goldman chief editor references bell r.e., studinger m., shuman c.a., fahnestock m.a. & joughin i. 2007. large subglacial lakes in east antarctica at the onset of fast-flowing ice streams. nature 445, 904–907. bones s. 2007. norway and past international polar years—a historical account. polar research 26, 195–203. goldman h.v. 2007. from the editor: polar research evolves, and norway and the ipy. polar research 27, 1–6. kohler j. 2007. glaciology: lubricating lakes. nature 445, 830–831. from the editor polar research 27 2008 1–6 © 2008 the author6 source, density and composition of sympagic fauna in the barents sea ole j . lbnne and bjbrn gulliksen b n n e , 0. j. & gulliksen, b. 1991: source, density and composition of sympagic fauna in the barents sea. pp. 28%294 in sakshaug, e., hopkins, c. c. e. & britsland, n. a. (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, 12-16 may 1990. polar research l o ( 1 ) . the sympagic fauna (= ice fauna) of the barents sea was investigated on nine different cruises in 1982 1988. each cruise lasted from two to five weeks. sampling techniques were based on scuba diving. the most abundant sympagic organisms were the polar cod (boreogadus saida) and the three amphipods apherusa glacialis, onisimus sp. and gammarus wilkitzkii. mean biomass-values (wet weight) of the invertebrate sympagic fauna ranged from 0 to 2 g/m2. values above 0.001 g/m2 were not recorded in five of the nine cruises. this is orders of magnitude lower than mean values recorded in multi-year ice north of svalbard and in the fram strait where values between 1 10 g/m2 are quite common. apherusa glacialis seemed to have the best spreading capacity of the three most conspicuous amphipods. gammarus wilkitzkii was most dependent on a passive transport with the ice. sympagic amphipods play an important part in a food chain from microalgae to polar cod and marine birds in areas covered with ice, especially in areas with multi-year ice. ole j . lmnne and bjgrn gulliksen, departmenf of marine biology, tromsm museum, university of trams@, n-9000 troms), norway. present address: the norwegian college of fishery science, unioersity of tromsg, n-9000 tromsc. norway. introduction the barents sea, one of the marginal seas to the arctic ocean, is seasonally partly covered with ice. the average water-depth is about 230m (wassmann & sakshaug 1987). water depths less than 50m are found on spitsbergenbanken and in nearshore areas only. the barents sea is, in the north, partly separated from the arctic ocean proper with a small number of islands situated between nordaustlandet (svalbard) and frans josef land. the age and origin of the sea ice in the barents sea is variable. usually it is a mixture of locally produced first-year (fy) ice and multi-year (my) ice, in addition to the similar sea ice types imported from the arctic ocean. there may be considerable variation in the relationship between the different components (vinje 1985). the ice cover reaches its maximum extent in february to may and may extend south of b j ~ r n ~ y a . most of the fy ice melts by the end of august. by that time, in most years, the ice edge has retreated to north of kong karls land in the northern barents sea (vinje 1985). areas north of svalbard and frans josef land are dominated by my ice from the perennial sea ice zone. the word “sympagic” means “with ice”, and we use this term to include all animals that live at least temporarily in or on the submerged parts of the sea ice. species are assigned to the sympagic assemblage of animals on the basis of observations of their actual presence (temporary or perma nent) in the ice or on the ice surface. our present understanding of the structure and composition of sympagic assemblages is to a large extent based on sampling and observations using scuba tech niques. most of our data, and data previously published by others, have been gathered from areas near shore-based stations or from ships working along the rim of the arctic basin. water depth and the duration of the ice-covered season affect composition and density of sympagic assem blages in such areas (carey 1985). there are fewer data available from areas with a permanent cover of sea ice. year-round studies from the soviet ice drift station np23 in t h e central arctic basin, however, have shown that a unique assemblage of species exists and utilises the ice substrate throughout its life cycle. sym pagic species therefore have been divided into an autochthonous group consisting of the permanent residents of the ice and an allochthonous group 290 ole j . l ~ n n e & bjorn gulliksen consisting of temporary residents (mel’nikov & kulikov 1980). the link between the sympagic assemblages occupying fy ice and assemblages associated with my ice has attained little attention. the aim of this paper is t o focus on the variations in density and relative distribution of the sympagic fauna found in the seasonally ice-covered barents sea and to compare our findings with similar data from the perennial sea ice zone further north. material and methods the sympagic faunal communities in the barents sea were studied on nine different cruises i n 1982 1988, each lasting from two to five weeks (gul liksen 1984; l ~ n n e & gulliksen 1991a). the cruises in the barents sea have together spanned the months from february through october. the sympagic iauna within the perennial sea ice zone north of svalbard and in the fram strait were studied on two different cruises in 1986 and 1988 ( l ~ n n e & gulliksen 1991b). sampling i n the field was based on different techniques using scuba equipment. this included the use of a suction sampler especially designed for collection of organisms on rough surfaces, in brine channels and from other habitats that are difficult to reach ( l ~ n n e 1988). also used were a plankton net with a straight upper frame suitable to haul along flat undersurfaces of the ice (gul liksen 1984), underwater-photography, and in situ observations. to quantify the abundance of the sympagic organisms, suction samples were taken within specific time intervals. predetermined areas of the undersurface were scraped and photo graphs of the organisms were taken within ref erence-frames of known sizes. (see l ~ n n e & gulliksen 1991a. b for detailed descriptions of sampling techniques and sampling locations). results and discussion three amphipods. apherusa glacialis, onisimus sp. and gammarus wilkitzkii, and the polar cod, boreogadw saida. were the most abundant sym pagic macro-organisms in the ice of the barents sea. onisimus sp. is most probably 0. glacialis only, but since it is difficult to distinguish from 0. nanseni it is denoted as onisimus sp. the amphipods gammaracanthus loricatus and isch yrocerus anguipes were relatively rare. nereis pel agica (epitoke stage), calanoid copepods (calanus finmarchicus. c. glacialis), the eaphausiid thy sanoessa inermis. the amphipod parathemisto lib elluh and others (table 1) were also recorded, but we regarded these organisms at present as planktonic and not belonging to the sympagic fauna. the most frequently occurring sympagic organ ism in the barents sea is a. glacialis. this species, which had a mean wet weight of o.oo58 ? 0.0022 g in the 1988 data, is mainly attached to the lower surface of the ice and on some occasions to the vertical floe edges. it is not usually associated with brine channels or crevices in the ice. onisirnus sp. occurred on the ice surface, but was more often found within small cracks and holes. its mean weight in our 1988 samples were almost an order of magnitude higher than a. glacialis, 0.01350 k 0.0728 g. in 1988, floating algal clumps were frequently recorded in holes i n the ice, and onisimus sp. were usually associated with these. individuals sampled in these clumps were often the same colour as the algae. the largest of the amphipods was g. wilkitzkii, which i n the barents sea in 1988 had a mean weight of 0.07280 k 0.0600 g. juveniles and young adults were most common in these samples. g . wilkitzkii is almost always found inside small holes or channels. if disturbed, it retracts and instantly attaches itself to the walls of the channels by the spiny appendages on pleopods six and seven. the polar cod, b . saida, is mostly observed between sandwiched ice floes or in melting holes and crevices of the ice ( l ~ n n e & gulliksen 1989). all specimens captured in the ice belonged to year-class i or 11. older fish descend to greater depths during spawning (ponomarenko 1968). the absence of other year-classes in the samples support the view that spawned polar cod do not return to the surface. no reliable values for the density of polar cod could be calculated, partly due to their patchy density and their mobility. they are difficult to collect between sandwiched ice floes. and the couple of hundred individuals we were able to catch using hand-held dip nets required several hours of diving. variation in biomass and abundance the total biomass of invertebrate sympagic fauna in individual localities in the barents sea usually sympagic fauna in the barents sea 291 table 1 . the relative occurrence of species collected in the barents sea (ssiz) and north of svalbard (psiz). ssiz psiz year: 1982 1983 1985 1986 1986 1987 1987 1988 1988 1986 1988 month: aug. m . 4 . a.-m. apr. m.-j. f.-m. oct. mar. may j.-a. sep. annelida polychaeta nereis pelagica * harmathoinae ind. mollusca crustacea limacina sp. ostraccda copepoda mysidacea amphipoda * apherusa glacialis onisimus spp. * gammarus wilkitzkii gammaracanthus loricatus parathemisto libellula * weyprechtia pengub anonyx nugax * ischyrocerus anguipes amphipoda ind euphausiacea thysanoessa inermis decapoda fandalus sp. chaetognatha sagitta sp. larvacea laruacea ind. ostracoda ind. calanus spp. mysis sp. x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x = rare (found on <50% of the stations). x x = common (found o n >50% of the stations), x x x = abundant (common on indicate sympagic species. >50% of the stations). north, almost at 81"n, at the time of freezing the preceding autumn. because of southerly winds during the winter it is probable that no old ice was transported into the barents sea. therefore it is likely that my ice was too far north of the investigated area for autochthonous sympagic animals to be able to colonise fresh ice. the highest values of biomass were recorded during years when it was possible to sample closer to my ice. this was the case in years when enough fy ice had melted for the ship to be able to enter such areas, and in the years when we had access to remote areas by the use of helicopters. the average biomass values from the barents sea were significantly lower than those recorded in my ice north of svalbard and in the fram varied between 0 to l g / m 2 (wet weight). the average value on a single cruise never exceeded 0.4g/m2 (fig. 1). an exception here are four stations visited in july 1986. average biomass values on my ice floes, probably drifted into the barents sea during the summer, were estimated to be 2.0 g/m2. on five of the nine cruises, values above 0.001 g/m2 were not recorded. five of six of these cruises took place in late winter/early spring, and the investigated areas were dominated by young fy ice. the cruise in spring 1985 was special in that no sympagic fauna was recorded, with the exception of a few large specimens of garnrnarus wilkitzkii near a drifting iceberg. from ice charts we observed that the ice edge was usually far 292 ole j. l ~ n n e & b j l r n gulliksen h 2r 90.. 0 0 . . 6 70.. l l i gga borcnts sco i north of svolbord 02 83 05 86 06 8 7 87 00 00 86 0 0 year fig. 1. average biomass values (wet weight) from 1 1 cruises in the barents sea and north of svalbard. first-year ice was most common in the barents sea. while multi-year ice dominated north of svalbard. strait. in such my ice an average of 4.7g/m2 (fig. 1) was recorded in 1986. biomass values recorded in 1988 were even higher, especially in the area just north of k v i t ~ y a . values from single locations here exceeded 50 g/m2 and the average from the whole cruise was 8 . 3 g/m2. due to the complicated three dimensional structure of the lower ice surface found in my ice in the perennial sea ice zone, most of the sampling was done at standardised time intervals. biomass values per unit area were then estimated by comparing these results with quantitative photographs (l0nne & gulliksen 1991b). these findings suggest that there is a transport of sympagic autochthonous faunal species from my ice in the polar basin into the barents sea. however, no apparent n-s gradient was recorded (lonne & gulliksen 1991a). the n-s pattern one might expect to find as a result of the “diffusion” 0 a . glociolis i g. wilkitzkii gga onisimui sp. 1983 1988 1982 i986 year lncreoaing totol density -) fig. 2. relative occurrence of the main autochthonous sympagic species. 1983.1988 and 1982 data are from the barents sea and of autochthonous sympagic animals from my ice to new habitats in fy ice might well be distorted by the complicated drift-pattern of the ice in the barents sea. because g. wilkitzkii is the least motile of the three most conspicuous autochthonous sympagic species (authors’ obs.), its presence might indicate the proximity of my ice. one should therefore expect to find higher biomass values on locations where g. wilkitzkii occurs compared to stations where this species is absent. this was tested on the 1983 material, where g. wilkitzkii occurred on 9 out of 33 sampled locations. the mean biomass values were significantly higher in the samples with g . wilkitzkii than in the samples without. this held true when the biomass of the same samples were compared after subtracting the g. wilkitzkii-component. apherusa glacialis comprised up to 90% of the sympagic specimens sampled. by comparing the years 1982, 1983 and 1988, when densities were high enough to make a relevant comparison, there was a tendency for the relative numbers of g. wilkitzkii to increase and a. glacialis to decrease as the total number of amphipods collected increased (fig. 2). the 1983 and 1988 samples were collected in may and june, in the southern part of the barents sea. there were few obser vations of my ice. the 1982 data were sampled in august and further north in the barents sea. my ice was relatively common. this tendency is accentuated when analysing the samples from my ice north of svalbard. fewer than 50% of the specimens collected in 1986 and 1988 were a . glacialis and the number of g. wilkitzkii increased from a maximum of 20% from the barents sea in 1982 to almost 40% in the samples taken north of svalbard (fig. 2). these findings strengthen the impression that the dominating sympagic fauna in the barents sea is recruited from the my ice in the perennial sea ice zone. a . glacialis seems t o be the most motile and was therefore found in greatest numbers far from my ice. g. wilkitzkii is more closely related to my ice and more dependent upon the move ment of the ice to recruit new areas. the spreading capability of onisimus sp. seems to be inter mediate. food chains although diet analysis of the sympagic organisms the 1986 data are from north of svalbard. in the barents sea has not been made, there are syrnpagic fauna in the barents sea 293 data on the diet of apherusa glacialis, onisirnus glacialis and garnrnarus wilkitzkii from eastern canada (bradstreet & cross 1982). all consumed microalgae, especially pennate diatoms, but g. wilkitzkii also ate crustaceans. this last obser vation corresponds well with our in situ obser vations of g. wilkitzkii and parathernistho libellula attacking smaller crustaceans. we have also frequently sampled onisirnus sp. with clumps of algae attached to its feeding apparatus. polar cod diet data from the barents sea were collected mostly from fy ice. here the fish fed merely on pelagic crustaceans, with calanoid copepods as the most important food (lonne & gulliksen 1989). this diet is quite similar t o that recorded from open waters of the barents sea (hognestad 1968). however, polar cod collected in my ice further north contained organisms more associated with the ice, and the three most abun dant items were p . libellula, a. glacialis, and onisirnus sp. ( l ~ n n e & gulliksen 1989). the sympagic amphipod g. wilkitzkii was not an important food item, even though this species, in 1986, accounted for 80% of the total biomass of the sympagic fauna where the polar cod were caught. only a few, small specimens of g. wil kitzkii were found in the polar cod stomachs. the avoidance of g. wilkitzkii by polar cod might be due to the “spiny morphology” and the larger size of this amphipod compared to the others in the sympagic fauna. our results were strikingly similar to that of cod taken respectively from the undersurface of offshore landfast ice and inshore ice cracks of the eastern coast of canada where copepods and amphipods dominated (bradstreet & cross 1982). there was also a size-selection in feeding of the canadian polar cod. diving seabirds such as the little auk (alle alle), briinnich’s guillemot (uria lornuia) and black guillemot (cepphusgrylle) are among the seabirds most likely to utilise the sympagic fauna as a food source. sympagic amphipods and the polar cod comprised a major part of the stomach contents from these three species sampled in ice-covered parts of the barents sea and north of svalbard in august 1986 (lonne & gabrielsen 1992). a clear indication of food specialisation was also observed. briinnich’s guillemots had the broadest diet, but with a preference towards g. wilkitzkii and polar cod. little auks fed on crustaceans only, with a preference towards the smaller species a . glacialis and calanus sp. whereas polar cod dominated the black guillemot diet. in spring 1985, a similar diet analysis reflected the lack of sympagic invertebrate organisms on the lower ice surface at this time. calanus finrnarcicus dom inated the little auk diet, while briinnich’s guille mots ate pelagic crustaceans such as p . libellula and pandalus borealis and polar cod. the black guillemot fed mainly on polar cod. it is likely that the sympagic fauna play an important role in seabird diets inside or close to the perennial sea ice zone. conclusions we have found a clear correlation between the occurrence of my ice and the occurrence of sym pagic fauna. the three dominant invertebrate sympagic species apherusa glacialis, onisirnus sp. and garnrnarus wilkitzkii are probably all autoch thonous sympagic species. these are sympagic organisms of which both sexes and all devel opmental stages occur in the ice habitat (mel’nikov & kulikov 1980). the less common garnrnaracanrhus loricatus and ischyrocerus anguipes are allochthonous sym pagic animals. allochthonous sympagic species are found temporarily in the ice (mel’nikov & kulikov 1980), and either planktonic, nektonic or benthic at other times of the year. g. loricatus and i . anguipes are relatively common in the benthos, and we suggest that this type of organism be called bentho-sympagic. bentho-sympagic ani mals are more frequent in shallow water areas. they were few in our studies which were generally in waters deeper than 200 m. we have called organisms that live partly as planktonic or nekton and partly in the sympagic habitat, pelago-sympagic. the polar cod, bor eogadus saida, is such an organism. the relative abundance of organisms varies from year to year and the relative abundance of the three most conspicuous sympagic species is not constant. a . glacialis, for instance, dominated assemblages collected in may/june 1983, but oni sirnus sp. and g. wilkitzkii were more common in may/june 1986 and 1988. this is possibly due to a stronger component of fy ice in 1983 than in 1986 and 1988. a . glacialis is the most motile species and has thus the best capacity to colonise fresh ice. acknowkdgemenn. this work is part of the pro mare pro gramme and has been financed by the university of t r o m s ~ and 294 ole j . l ~ n n e & b j ~ m gulliksen the norwegian research council for science and humanities (navf). the authors would like to thank crew and colleages and k / v andenes for assistance during the expeditions. we should also like to thank dive master b. seim for excellent diving companionship and management of diving operations. on r / v lance. m;v polarbjbrn. k!v nordkapp. k:v senja references bradstreet. m. s w. & cross. w. e. 1982: trophic relation ships at high arctic ice edges. arrric 35(1). 1-12, carey. a . g . , jr 1985: marine ice fauna: arctic. pp 1 7 ~ 1 9 0 in horner. r . a ( e d . ) : sea i c e biora. crc prcss. boca raton. florida gulliksen, b. 1984: under-ice fauna from svalbard waters. sarsia 6 9 . 17-23. hognestad p. t. 1968: i . observations on polar cod in the barents sea. r a p p . p . v . rkun. corn. inr. explor. mer 158. 1 2 6 1 3 0 . lsnne. 0. j . 1988: a diver-operated electric suction sampler for sympagic ( = under-ice) invertebrates. polar res. 6. 135 136. lsnne. 0. j . & gulliksen, b. 1989: size, age and diet of polar cod. boreogadus saida (lepechin 1773). in ice covered waters. polar b i d . 9 . 187-191. lsnnc. 0. j . & gullikscn. b. 1991a: on the distribution of sympagic macro-fauna in the seasonally ice covered barents sea. polar b i d 11. 457-469. lsrne. 0. j . & gulliksen. b. 1991b: sympagic macro-fauna from multiyear sea-ice near svalbard. polar b i d . j i . 471 477. lsnnc. 0. j . & gabriclscn. g. w. 1992: summer diet of seabirds feeding i n sea-ice covered waters near svalbard. polar biol i n press. mel'nikov. i a . & kulikov. a . s . 1980: the cryopelagic fauna of the central arctic basin. b i d tsenfal'nogo arkricheskogo barseina. 97-1 1 1 . (canadian translation of fisheries and aquatic sciences 4910 (1983)). ponomarenko. v. p. 1968: some data on the distribution and migrations of polar cod in the seas of the soviet arctic. r a p p . p . r . reun. cons. lnr. e x p l o r . m e r 158. 131-135. vinje. t . 1985: the physical environment. western barents sea. drift. composition. morphology and distribution of the ice ficlds i n the barents sea. norsk polarinsr. s k r . j79c. wassmann. p. & sakshaug. e. 1987: barentshavets skologiske 26 pp. grunntrekk. naturen 4 . 151-158. por_020.fm 212 polar research 26 2007 212 © 2007 the author correspondence robert k. headland, scott polar research institute, lensfield road, cambridge cb2 1er, uk. e-mail: rkh10@hermes.cam.ac.uk. b o o k r e v i e w review of due south , by john kelly (2004). oxford: signal books. 61 pp. isbn 1-902669-90-8 this small volume is basically the diary of john kelly, who visited the british antarctic survey station on signy island in the south orkney islands. it includes about 60 monochrome plates (mainly half-page ones), a few sketches and a map of the island. the text is essentially a diary of the author’s time, from beginning in the falkland islands, sailing aboard rrs ernest shackleton , staying on the island from 25 january to 8 march 2003 to the return journey. as well as the illustrations, the text is accompanied by brief poetical extracts by the author and others. it is substantially a personal account of the visit, and may be best understood by those who have seen exhibitions of his artistic works. impressions of signy island are confined to modern ones gained during the artist’s visit; thus, there is no reference to the norwegian aspects of its history (neither the derivation of the name from signy, daughter of the whaling captain petter sørlle, nor the graves of five whalers on factory bluff, is mentioned). similarly, reference to the continuing scientific research conducted at the station is minimal although he accompanied a limnological survey. signy island is small and so it is possible to see much of it during a long day’s walk. this, as well as time in some of the field huts, is a specific point of interest as kelly accompanies station staff visiting places distant from the main station. the period when he was on the island corresponded to the quite rapid change from near the height of summer to the beginning of winter. the vast movement of wildlife, particularly its exodus with the first storms of winter, intrigued him. the cover of the book states that “ due south catalogues moments in time experienced . . . not simply a visual record, but an account of the emotions and fleeting thoughts of life in the ‘freezer’ ”, which describes the slim volume well. the visit was one in a series of artist and writer’s programmes of the british antarctic survey. for many years new zealand, the united states, australia and other countries with stations in the antarctic have organized similar events, each yielding a distinct concept of the antarctic. regional effects of climate change on reindeer: a case study of the muotkatunturi region in finnish lapland susan e. lee, malcolm c. press, john a. lee, tim ingold & terhi kurttila few studies have investigated current climate changes for high latitude regions, and the impact of such changes on reindeer and indigenous people. previous work by other authors has identified snow and ice conditions in winter as being critical in determining the availability of forage for reindeer. deep snow makes it difficult to access food. lack of food weakens the herd and can reduce the allocation of nutrients to the development of the foetus in the female deer. climate data for lapland, northern finland, and karasjok, northern norway, are examined, together with reindeer calf numbers for the period 1977 to 1994 for the muotkatunturi region (68"n 25"30'e). between 1883 and 1993, precipitation increased but temperatures showed no clear warming or cooling trend. however, since the late 1980s, temperatures have increased. a regression analysis on the climate and reindeer data found that the wanner the winter prior to the rut, the fewer the live calves recorded the following year (r = 0.529, p < 0.05). also, the wetter the winter prior to the rut, the fewer the calves recorded (r = 0.427, p < 0.10). in contrast, the warmer the autumn prior to their birth, the greater the number of calves recorded (r = 0.474, p < 0.10). these results suggest that as climate changes and winters become warmer and wetter with increased snowfall, calf numbers will decline. these findings have important implications for the saami people who are heavily dependent on the reindeer for their livelihood. s. e. lee, m . c. press & j. a . lee, dept. of animal and plant sciences, western bank, university of shefield, sheffield sio ztn, uk. t. ingold & t. kurttila, dept 3qy, scotland, u k . general circulation models (gcms) predict that regions in high latitudes are likely to experience large increases in temperature with a doubling in current atmospheric c 0 2 concentrations. this increase in temperature is likely to be particularly noticeable in winter up to 5°c (cattle & crossley 1995). rainfall is also expected to increase (maxwell 1992) although this may vary spatially. this paper is concerned with recent climate change in northern finland where the vegetation is particularly sensitive to environmental variables, and where there is a strong human dependence on natural resources. plant growth and distribution in this region are heavily constrained by the duration of the snow-free period, by generally low air and soil temperatures, soil moisture and low soil nutrient availability, as in much of the arctic (press et al. 1998). in lapland, the local indigen of sociology, university of aberdeen, aberdeen a b 2 4 ous people -the saami -have strong links with the natural environment, both through their reindeer herding and through their dependence o n berries and mushrooms to supplement their diet. they are heavily dependent on reindeer for their livelihood. there is mounting concern about the effect of a changing climate on the distribution of lichens, the main winter food source for the reindeer. deep snow causes reindeer difficulties in accessing food. they have to move around more frequently and use valuable energy. this leads to the death of weaker members of the herd and, for pregnant females, a reduction in energy and nutrients to developing foetuses (szther 1985, cited in post et a]. 1997; langvatn et al. 1996). the autumn months are important as this is the season of the deer rut. if autumn is warm and wet this means that there is plenty of food accessible for the lee et al. 2000: polar research 19(1), 99-105 99 adult animals and they are in good physical condition. if the weather is cold and dry, the snow should be powdery and easier for the reindeer to reach their food. however, if a cold, dry autumn is interrupted by a few warm spells, there are likely to be considerable ice layers formed over the lichen on the ground, which would make it harder for the reindeer to access their food, reducing their energy levels. this has been noted for red deer (cervus elaphus) in norway (langvatn et al. 1996). furthermore, albon et al. (1992, cited in post et al. 1997) observed that the fecundity of female red deer in norway was negatively correlated with winter precipitation while they were pregnant. this paper concerns climate effects on reindeer numbers as identified within a managed reindeer herd in northern finland. a combined ecological/ social anthropological study was undertaken in lapland from 1995 to 1997 to determine the changes in climate which have occurred in this particular region over the last 100 years, both from a scientific viewpoint, using official meteorologi cal measurements, and from the saami viewpoint. the results from the meteorological analysis are presented in lee et al. (2000). the northern half of finland is separated into 57 reindeer husbandry units, called paliskunta, with a total land area of 114 355 km2. muotkatunturi, one of these units, covers a land area of 2482 km2. the most southerly paliskunta are situated in the oulu parish. one-third of all finnish reindeer are found the 12 northernmost units, situated in the saami region. hence these areas are extremely important for the reindeer herding economy in finland. the reindeer herding association (paliskuntain yhdistys) is responsible for reindeer management, which includes husbandry, economy and public relations. during the reindeer herding year 1996 97 there were a total of 202 449 live adult reindeer and 88 532 calves recorded for all paliskunta. for the same period there were 8640 live adult reindeer and 4375 calves in the muotkatunturi paliskunta. reindeer herding in finland is highly managed through the use of fencing which restricts the movement of reindeer. to focus on the influence of climate in this paper, the number of live calves born was selected as the best indicator of the health of the herd. the number of animals slaughtered in the autumn round-up is determined by the number of animals available and their potential market price. the bulk of a reindeer herd is female (for example, between 1992 and 1996 female reindeer were 92 or 93% of the herd in the muotkatunturi region). in this study, the number of live reindeer calves recorded by the reindeer herding association for the muotkatunturi region between 1977 and 1994 were compared with the seasonal temperature and precipitation anomalies for 1976 to 1993. during this period there were a number of changes in management strategies by the reindeer herders in finland in response to economic conditions, technological developments and government poli cies. such strategies led to a rapid increase in the number of reindeer during the late 1970s and into the 1980s, with a peak occurring in 1990. since then there has been a decline in reindeer numbers. this decline is due to a number of factors, including government intervention, decreased economic returns caused by increased slaughtering and supplementary feeding, and problems of overgrazing, along with adverse weather condi tions. here we focus on an analysis of both the climate data in the region and reindeer calf numbers to determine how reindeer may be influenced by temperature and precipitation. the reindeer calf numbers are analysed with these climate data and the results presented and discussed. no snow data have been analysed, but it is assumed that in a warm, wet winter there will be more snowfall than would occur in a cold, dry winter. reindeer reindeer are particularly dependent on various species of lichen in winter, which represent an easily digestible food supply rich in carbohydrates. finnish reindeer spend their winter in the lowland forests, and depend on the food resources found in these forests for their survival in this season. the spatial and temporal distribution of plants is considerably affected by climatic conditions. for example, after snowy winters (which are also warm) plant growth begins earlier and is more variable among sites due to differences among landscapes (forchhammer et al. 1998). severe weather conditions in spring, or a late snow melt, can have important effects on reindeer populations and be responsible for the death of young or weak animals after the winter starvation. several authors (helle 1984; helle & tarvainen 1984a; collins & smith 1991) have identified 100 regional effects of climate change on reindeer snow and ice conditions in winter as critical in this analysis included comparisons with spring, determining the availability of forage. also, in years when insect pest populations are particularly large, often during warm summers when repro ductive rates are high and the female insects lay their eggs, harassment can lead to reduced weight gain before winter (helle & tarvainen 1984b). in northern finland, the calves from herded reindeer tend to be born in the period 10 to 29 may (eloranta & nieminen 1986) but slightly later, into early june, for forest reindeer (helle 1981). reindeer owners and herders out of a total of around 7000 reindeer owners in finland, two-thirds own fewer than 25 teindeer and only 7% own 100 or more reindeer. there are around 100-120 reindeer owners within the muotkatunturi region, most of whom also herd the reindeer. the majority of herders in this region are saami although some herding is also carried out by finns. reindeer are allowed to graze naturally within the fenced boundaries. in winter, some supplementary feeding occurs which, while less than further south, is on the increase. reindeer herding is an important source of income for the saami, bringing in between half and three-quarters of their gross earnings. how ever, this income has to be supplemented by agricultural and forestry work, as well as other cash-earning jobs. methods temperature and precipitation anomalies from 195 1-1980 mean temperature and mean precipita tion values were extracted from the global historical climate network (ghcn) (vose et al. 1992) created by the global climate laboratory of the national climatic data center (ncdc/gcl), usa. temperature and precipitation anomaly data were extracted for the 5" x 5" grid covering lapland and plotted for the period 1880 to 1993. a 10-year gaussian filter was used to smooth these data over the 11 3 year period. live calf numbers recorded during the period from 1 june 1977 to 31 may 1994 were extracted from the february issues, 1979-1996, of the magazine poromies, produced by the paliskuntain yhdistys, and a regression analysis was performed. summer, autumn and winter temperatures and precipitation for karasjok (69"47'n, 25"50'e) in northern norway (the nearest meteorological station to where the saami reindeer herders operate). as the meteorological records for karasjok ceased in 1970, but meteorological data are still collected for sodankyla (67"37'n, 26"65'e), the karasjok temperature data (1 908 1970) and precipitation data for 1907-1970 were regressed against those data for sodankyla for the same time periods, for each season and for the year. these regressions enabled temperature and precipitation anomalies for the period 1970-1 993 to be calculated for karasjok. the seasons fall into the four meteorological categories of winter (december, january, february), spring (march, april, may), summer (june, july, august) and autumn (september, october, november). these seasonal data have been derived from the monthly data so, for example, current winter temperatures for 1987 would be derived from adding together the monthly temperature anomalies for december 1986, january 1987 and february 1987 and dividing by 3 to obtain a mean winter temperature anomaly for 1987. these data have been extracted from the national climatic data center (ncdc) records. the close relationship between the sodankyla and karasjok temperature and precipi tation data for all seasons is statistically significant the seasonal anomalies were extracted for both temperature and precipitation from the calculated karasjok data for the years 1976-1993 and plotted against the number of live reindeer calves for the year previous to which the calves were born. in addition, the anomalies for the current winter and spring were also plotted against the number of calves. the results are shown in table 1. for example, the number of calves recorded in 1985 would be regressed against the previous autumn months of september, october and november 1984, the previous winter months of december 1983, january 1984 and february 1984, and the current winter months of december 1984, january 1985 and february 1985. (p < 0.01). results there is no discernible warming trend between 1880 and 1993, but a clear warm period occurs lee et al. 2000: polar resenrch 19(1), 99-105 101 table 1. results of the regression of the number of live calves (y) on the seasonal temperature and precipitation anomalies recorded at karasjok in norway, 1976-1994 (x). it should be noted that, except for the current spring and winter, the climate data are for the period 1 9 7 6 1993 and the reindeer calf data are for the period 1977-1994 (see text). season r regression equation p 1 ' " u i ] i temperature current spring ( 1977-1 993) current winter (1977-1993) i ~ ~~~ y = 1 1 . 6 4 5 ~ + 1337.4 0.028 ns y = 4 2 . 2 3 ~ + 1290.4 0.246 ns previous autumn y = 2 4 6 . 4 4 ~ + 1440.6 0.474 <0.1 previous winter y = -91.684~ + 1223.2 0.529 <0.05 previous summer y = 1 4 3 . 7 1 ~ i 1292.8 0.246 ns previous spring y = 1 3 9 . 3 5 ~ + 1382.8 0.341 ns precipitation current spring y = 6 . 4 5 6 7 ~ + 1265.2 0.107 ns current winter y = 2 2 . 2 2 2 ~ + 1438.9 0.292 ns (1977-1993) previoub autumn y = 7 . 9 7 4 1 ~ + 1301.7 0.153 ns previous summer y = 1 . 7 4 4 4 ~ + 1284.2 0.100 ns previous spring y = 6 . 5 3 3 9 ~ + 1250 0.112 ns ( 1977-1 993) previous winter y = 3 2 . 6 8 ~ + 1477 0.427 <0.1 d.f. = 17. ns is not significant. 1880 1890 1900 1910 1920 1930 1940 1950 1980 1970 1980 1990 1660 1690 1900 1910 1920 1930 1940 1950 1960 1970 1980 w90 fig. 1. northern finland surface air temperatures by year, 1880 to 1993. data are expressed as "c anomalies from 1951-1980. the smooth curve was obtained by using a lo-year gaussian filter. f i g . 2. northern finland precipitation by year, 1880 to 1993. data are expressed as mm anomalies from 1951-1980, the smooth curve was obtained by using a 10-year gaussian filter. l n 5 z z v moo l d -3 -2 -1 0 1 1 1 2 lo m > 3888 2500 i ,l " i -5 0 5 -1 0 kafasjok previous autumn temperature anomaly ("c) karasjok previous winter temperature anomaly ("c) f i g 3 . scatter plot of the number of live reindeer calves vs. fig. 4 . scatter plot of the number of live reindeer calves vs. previous autumn temperature for the period 1977-1994. previous winter temperature for the period 1977-1994. y = 2 4 6 . 4 4 ~ + 1440.6, r = .474 and p < 0.10. y = 9 1 . 6 8 4 ~ + 1223.2, r = ,529 and p < 0.05. 102 regional effects of climate change on reindeer 500 -1 0 0 10 20 30 prev winter precipitation anomaly (mm) f i g . 5. scatter plot of the number of live reindeer calves vs. previous winter precipitation for the period 1977-1994. y = 3 2 . 6 8 ~ + 1477, r = ,427 and p < 0.10. between 1925 and 1948 with temperatures up to 3.2"c above the 1951-1980 mean value (fig. i). a number of colder periods can also be identified, for instance, the first decade of the 20th century, the late 1960s and the midto late 1980s. since the late 1980s there has been a gradual warming with the positive temperature anomalies increasing. the dominant influence on the annual temperature in this region is the winter temperature (lee et al. 2000). also, though not shown here, summer and autumn temperatures decreased in the early 1990s, and spring and winter temperatures increased (lee et al. 2000). precipitation has increased during the period 1880 to 1993 (fig. 2 ) . this linear trend was found to be significant for all seasons, particularly spring (r = 0.460, p < 0.001) and winter (r = 0.486, p < 0.001) as well as annually (r = 0.487, p < 0.001). during the early 1990s, spring and winter precipitation has increased, autumn pre cipitation has decreased but there has been little change in the summer precipitation (lee et al. 2000). the results show a positive correlation between the temperature of the previous autumn and the total number of live calves (r = 0.474, p < 0.10) (fig. 3). this means that the warmer the previous autumn, the greater the number of calves. a further significant correlation was also found to exist between the total number of live calves and the temperature of the previous winter. this was a negative relationship, i.e. the warmer the winter prior to the rut, the fewer the calves born the following spring (r = 0.529, p < 0.05) (fig. 4). in addition, a negative correlation was found between the number of live calves and the amount of precipitation during the winter prior to the rut 2 e :: 19771 9791 981 198319851987 i9891991 1993 t o prev. winter pptn -live calves fig. 6 . the number of live reindeer calves born between 1977 and 1994 (muotkatunturi region, finland) with temperature and precipitation anomalies for the winter of the previous year. data are expressed as "c and mm anomalies from 1951-1980, (r = 0.427, p < 0.10) (fig. 5). the greater the precipitation, the fewer the calves. no other significant relationships were found between reindeer numbers and seasonal precipitation over this time period. calf data were plotted against the winter temperature and precipitation anomalies (fig. 6). it can be seen that when the previous winters are warm and wet (i.e. when the anomalies are positive) the numbers of reindeer calves decrease, but when they are cold and dry the numbers increase. discussion the herding of reindeer is of great importance to the saami as it is part of their traditional way of life, as well as providing an income. the greater the number of reindeer owned the higher the status of the owner within saami society. this is particularly the case in the muotkatunturi area. although many saami herders have additional employment, reindeer herding is still regarded as being of high cultural importance. the muotkatunturi area provides about 4% of the reindeer in finland and covers 2% of the overall herding area. it is within the main reindeer producing area of finland and herds considerable more reindeer than the southern herding areas. it can therefore be considered to be fairly represen tative of northern finnish reindeer husbandry. however, finnish reindeer herding is unlike other herding within fennoscandia in that the reindeer are controlled by fences. in other regions of fennoscandia reindeer are allowed to roam freely and are less protected from predators. lee et al. 2000: polar research 19(1), 99-105 103 there has been much work carried out on the reproductive success of cervids in relation to climatic and environmental factors (picton 1984; szther & heim 1993) and body weight (clutton brock & albon 1983). from studies on red deer, post et al. (1997) state that animals with low birth weight tend to produce low birth weight calves which are vulnerable and less likely to survive (albon et al. 1987). they also point out that variations in climate may influence the population dynamics of red deer through effects on winter survival and growth in utero, which later affects survival and fecundity of adult animals (albon et al. 1987). forchhammer et al. (1998) found that the abundance of red deer decreased following warm snowy winters. this they attributed to higher winter mortality. however, there is an increase in the fecundity of deer born following' snowy winters because of improved forage quality and a longer growing season (post et al. 1997; for chhammer et al. 1998). vibe ( 1 967) found from an analysis of reindeer populations on greenland that reindeer coped well when the winter climate was cold and dry, even with the poor quality vegetation; but in winters which were wet and warm, the vegetation was covered by thick layers of snow and ice and reindeer died from the lack of food. from their work in the oraniemi cooperative, finnish lap land (67"50"), kumpula & nieminen (1992) also found that the annual variations in calf production were explained best by snow conditions during the previous winter and spring and their effects on the nutritional status of the females. it has been assumed for this paper that the number of live calves recorded provides an indication as to the condition of the herd. there are problems with this assumption: there is the chance that some weak calves may die over the summer before the autumn round-up, and a high number of calves does not necessarily mean that the herd is healthy. however, the difference in the number of live calves between years serves as a reliable indicator as to whether the herd numbers are rising or falling. the effects of management practices have not been explicitly included in this analysis, but it is assumed that climate affects management decisions through its influence on the reindeer. even if the overall reindeer numbers rise and fall in response to external economic factors there will also be an underlying response to climatic effects. the saami themselves are well aware when reindeer numbers have fallen due to adverse weather and are keen to preserve their herd. this is done by adjusting the number of animals slaughtered. in northem lapland there is increasing use of supplementary food in winter by the herders. this means that there is less risk of winter starvation for the animals and some natural forage may be protected. it is expected that with climate change the faster growing vascular plants may out compete the slower growing lichens, which will affect the eating habits of the reindeer. vare et al. (1996) examined the changes in the distribution of plant species with grazed and ungrazed sites in north-eastem fennoscandia and found that although there was a reduction in the biomass of vascular plants with grazing there was no change in their coverage. there was also a reduction in lichens such as cladina stellaris at grazed sites. however, there was an increase in other lichens such as c. arbuscula and c. rangiferina together with bryophytes, especially dicranum spp., which benefited from grazing. it is interesting to note that there is no significant relationship between the number of live reindeer calves and the temperature and precipitation of the winter and spring of the year in which they were born (table 1). it appears that even if there are adverse winter and spring conditions (i.e. it is very wet or very cold) when the calves are young and there is high calf mortality, the overall number of calves has already been determined by the preceding autumn and winter conditions. this paper has highlighted the effects of autumn and winter temperatures and precipitation on the number of reindeer calves. it would appear that the climate has influenced the reproductive success of the female deer. it is clear that if winter temperatures continue to increase as predicted by climate models this will lead to further problems for the winter survival of reindeer. the saami people will need to take steps to ensure that they are able to adapt to these changing circumstances to preserve both their herds and the vegetation on which they feed. conclusions there is no discernible warming trend between 1880 and 1993 for the annual time series of temperature, but a clear warm period occurs between 1925 and 1948. 104 regional effects of climate change on reindeer a since the late 1980s there has been a gradual warming. a precipitation has increased during the period 1880-1993. this is significant for all seasons, particularly spring and winter, as well as annually. a a positive correlation was found between the temperature of the previous autumn and the total number of live calves (r = 0.474, p < 0.10). this means that the warmer the previous autumn, the greater the number of calves. a in addition, a negative correlation was found to exist between the total number of live calves and the temperature of the winter prior to the rut, i.e. the warmer the previous winter, the fewer the calves (r = 0.529, p < 0.05). a a negative correlation was also found between the number of live calves and the amount of precipitation (r = 0.427, p < 0.10) during the winter prior to the rut, i.e. the wetter the previous winter, the fewer the calves. acknowledgements. this paper is the result of an economic and social science research council (esrc)-funded colla borative project among the authors. i would also like to thank the eu-funded barents sea impacts study project and prof. teny callaghan, sheffield centre for arctic ecology, for allowing me to attend this conference, and dartmouth college, for providing me with the necessary funding. in addition, i wish to thank the three anonymous referees for their helpful comments. references albon, s. d., clutton-brock, t. h. & guinness, f. e. 1987: early development and population dynamics in red deer. 11. density-independent effects and cohort variation. j . anim. ecol. 56, 69-8 1. cattle, h. & crossley, j. 1995: modelling arctic climate change. philos. trans. r. six. lond., ser. a , 352, 201-213. clutton-brock, t . h. & albon, s. d. 1983: climatic variation and body weight of red deer. j. wildl. manage. 47, 1197 1201. collins, w. b. & smith, t. s. 1991: effects of wind-hardened snow on foraging by reindeer (rangifer tarandus). arctic 44, 2 17-222. eloranta, e. & nieminen, m. 1986: calving of the experimental reindeer herd in kaamanen during 197@85. rungijer, spec. h u e 1, 115-121. forchhatnmer, m. c., stenseth, n. c., post, e. & langvatn, r. 1998: population dynamics of norwegian red deer: density dependence and climatic variailon. proc. r . s o c . lond., ser. helle, t. 1981: studies on wild forest reindeer (rangifer tarundus fennicus lonn.) and semi-domesticated reindeer (rangijer tarandus tarandus l.) in finland. acta univ. oulensis, ser. a, 107, 1-34. helle, t. 1984: foraging behaviour of the semi-domestic reindeer (rangifer tarandus l.) in relation to snow in finnish lapland. rep. kevo subarct. res. stat. 19, 3 5 4 6 . helle, t. & tarvainen, l. 1984a: determination of the winter digging period of semi-domestic reindeer in relation to snow conditions and food resources. rep. kevo subarct. res. stat. 19.49-56. helle, t. & tarvainen, l. 1984b: effects of insect harassment on weight gain and survival in reindeer calves. rangijer 4, 24 27. langvatn, r., albon, s. d., burkey, t. & clutton-brock, t. h. 1996: climate, plant phenology and variation in age of first reproduction in a temperate herbivore. 1. anim. ecol. 65, 653-670. lee, s. e., press, m. c. & lee, j . a,. 2000: observed climate variations during the last 100 years in lapland, northern finland. int. j . clim. 20, 329-346. maxwell, b. 1992: arctic climate: potential for change under global warming. in f. s . chapin 111 et al. (eds.): arctic ecosysterns in a changing climate. an ecophysiological perspective. pp. 11-34. san diego: academic press. paliskuntain yhdisfys (association of reindeer herders) 1979 1996: tilastoja vuodelta. poromies (statistics. reindeer herder) 2. p.o. box 8168, koskikatu 33a, sf-96101 rovaniemi, finland. picton, h. d. 1984: climate and the prediction of reproduction of three ungulate species. j . appl. ecol. 21, 869-879. post, e., stenseth, n. c., langvatn, r. & fromentin, j.-m. 1997: global climate change and phenotypic variation among red deer cohorts. proc. r. soc. lond., ser. b-biol. sci., 264, 13 17-1324. press, m. c., potter, 3. a., burke, m. 3. w., callaghan, t. v. & lee, j. a. 1998: responses of a sub-arctic dwarf shrub heath community to simulated environmental change. j. ecol. 86, 315-327. szether, b.-e. 1985: annual variations in carcass weight of norwegian moose in relation to climate along a latitudinal gradient. j . wildl. manage. 49, 977-983. srether, b.-e. & heim, m. 1993: ecological correlates of individual variation in age at maturity in female moose (alces ulces): the effects of environmental variability. j . anim. ecol. 6 2 , 4 8 2 4 8 9 . vibe, c. 1967: arctic animals in relation to climatic fluctua tions. medd. gr@nland i70(5), 23-180. vose, r. s . , schmoyer, r. l. steurer, p. m., peterson, t. c., heim, r., karl, t. r. & eischeid, j. k. 1992: the global historical climatology network: long-term monthly tem perature, precipitation, sea level pressure, and station pressure data. version 1. ornli’cdiac-53, ndp-041. oak ridge, tn: carbon dioxide analysis center. 6-biol. sci., 265, 341-350. lee et al. 2000: polar research 1 9 ( i ) , 99-105 105 ratkova.indd 95ratkova & wassmann 2005: polar research 24(1–2), 95–110 sea ice algae in the white and barents seas: composition and origin tatjana n. ratkova & paul wassmann to examine algae populations, three expeditions (in march 2001, april 2002 and february 2003) were conducted in the guba chupa (chupa estuary; north-western white sea), and one cruise was carried out in the open part of the white sea in april 2003 and in the northern part of the barents sea in july 2001. sea ice algae and phytoplankton composition and abundance and the content of sediment traps under the land-fast ice in the white sea and annual and multi-year pack ice in the barents sea were investigated. the community in land-fast sea ice was dominated by pennate diatoms and its composition was more closely related to that of the underlying sediments than was the community of the pack ice, which was dominated by fl agellates, dinofl agellates and centric diatoms. algae were far more abundant in land-fast ice: motile benthic and ice-benthic species found favourable conditions in the ice. the pack ice community was more closely related to that of the surrounding water. it originated from plankton incorporation during sea ice formation and during seawater fl ood events. an additional source for ice colonization may be multi-year ice. algae may be released from the ice during brine drainage or sea ice melting. many sea ice algae developed spores before the ice melt. these algae were observed in the above-bottom sediment traps all year around. three possible fates of ice algae can be distinguished: 1) suspension in the water column, 2) sinking to the bottom and 3) ingestion by herbivores in the ice, at the ice–water interface or in the water column. t. n. ratkova, shirshov institute of oceanology, academy of sciences of russia, nakhimovsky ave. 36, 117997, moscow, russia, trat@orc.ru; p. wassmann, norwegian college of fishery science, university of tromsø, no-9037 tromsø, norway. high concentrations of organisms in polar sea ice have been well documented (e.g. horner 1985; lizotte 2003). sea ice is inhabited by diverse communities, including bacteria, algae, protists and metazoans (e.g. melnikov 1997). often the fl ora and fauna are not evenly distributed in the ice, but occur in specifi c microhabitats in different parts of the ice fl oes (horner 1985; syvertsen 1991; gradinger 1999). such communities have been studied in detail, but the current knowledge of the biological processes involved during sea ice formation and melting are still inadequate (gradinger & ikävalko 1998; weissenberger & grossmann 1998). there are several hypotheses regarding the origin and fate of sea ice communities (horner 1985). sieving of water by densely packed ice crystals has been observed repeatedly and appears to constitute an important mechanism for accumulation of algae cells on the ice under-surface (syvertsen 1991; melnikov 1997). the composition of sea ice algae off the shelves suggests that this population derives from pelagic algae inhabiting underlying water masses or from sea ice algae at the ice edge or polynyas (syvertsen 1991; druzhkov et al. 2001). in shallow water areas benthic algae may be included in the suc96 sea ice algae in the white and barents seas cession cycle (poulin 1990; gogorev 1998). through various research programmes we studied and compared the ice fl ora of the white and barents seas, two regions inadequately studied with regard to ice biota. we investigated in particular the peculiarities of the vertical distribution of the sea ice algae under different conditions and the succession of this distribution during the late winter/early spring in the land-fast ice in the white sea. the differences in the algae species composition in different types of ice and the relationships between taxa within the ice and water column were also quantifi ed. materials and methods three cruises were conducted to the guba chupa (chupa estuary; north-western white sea) in february 2003, march 2001 and april 2002. one cruise was carried out in the open part of the white sea (april 2003), where the stations were located in the marginal ice zone (miz) in the southern part of gorlo (north-eastern white sea). one cruise was carried out in the miz of the northern part of the barents sea in july 2001 (table 1). ice cores from the white sea were obtained with a ring corer (diameter 14.5 cm) and divided into three or four sections: upper 10 cm, lower 3 5 cm, and a middle part, which was cut into two parts if the total ice thickness exceeded 40 cm. the sections were melted at low temperatures (< 2 °c) without addition of fi ltered water. the salinity of the white sea ice is low (krell et al. 2003), and we deem that the algae were not being exposed to osmotic stress during melting. in the barents sea, ice cores were collected with an ice auger (diameter 9 cm). the lowermost 20 30 cm of each ice core was melted in double its volume of fi ltered seawater at low temperatures. samples from the water column below the ice were also obtained in both regions (appendix). the volume of the sea ice and water samples ranged from 100 to 4500 ml, according to the abundance of the algae. to investigate the possible importance of sea ice algae for the vertical fl ux of biogenic matter, cylindrical sediment traps were deployed below the ice: in the white sea (guba chupa) the traps were preserved with formaldehyde and exposed for a week at 20 m depth. traps were also deployed above the bottom in the kandalaksha bay (depth 280 m) and nine samples (each representing one month) were taken from august 2002 to may 2003. in the barents sea, traps were deployed without preservation for one day at 30 m depth . the height/diameter ratio of the traps was 3.11 for the white sea and 3 for the barents sea. temperature and salinity were measured with standard ctd profi lers. all samples were preserved with a glutardialdehyde–lugol–ethanol solution and developed according to ratkova & wassmann (2002). small fl agellates were counted in a fuchs-rosenthal chamber at 600× magnifi cation prior to any concentration of samples. after they had settled, larger algae were counted in chambers with rultable 1. biomass (mg c m–3) of the sea-ice algae (“algae”) in the lowermost layer of the ice in the barents (5 34 cm of 100 135 cm cores) and in the white sea (5 10 cm of 37 56 cm cores) and of phytoplankton (“phyto”) below the ice. barents sea white sea (pack ice) white sea (land-fast ice) 77° 50' n, 29° 45' e 78° 20' n, 27° 20' e 82° 00' n, 26° 00' e 65° 40' 66° 10' n, 40° 10' 40° 50' e 66° 20’n, 33° 40' e 3 july 2001 6 july 2001 9 july 2001 19–20 april 2003 8 february 2003 18–26 march 2001 6–8 april 2002 algae phyto algae phyto algae phyto algae phyto algae phyto algae phyto algae phyto diatoms 7.58 5 44 49.2 1 7 254.6 1 7 44 478 11 12 1.49 0. 07 0.31 94 598 1 64 1136 35188 1 94 dino fl agellates 0.49 34 80 14.0 25 33 11.0 1 2 1.3 21.7 0.01 1.06 0.49 0.03 0.18 3.1 37.5 0.02 1 24.5 178.6 1 28 other fl agellates 17.0 82 299 86.8 82 173 76.5 32 74 36 49 27 94 4.4a 0.5 2.2a 8.6 35.7 11 359 3.8 61.7b 1 525b total 28.3 154 407 150 117 218 343.8 35 83 87 565 39 109 6.49 0.12 2.69 115.9 674.1 15 444 1164 35428 3 647 a according sazhin et al. in press. b according sazhin et al. 2004. 97ratkova & wassmann 2005: polar research 24(1–2), 95–110 ings, at 300× magnifi cation in a 0.06 ml chamber and at 150× magnifi cation in a 1.0 ml chamber. the carbon content of the algae was calculated according to strathmann (1967) for diatoms with a cell volume > 3000 µm3, and according to mendendeuer & lessard (2000) for all other protists. results physical environment the temperature of the water in the white sea seldom reached the freezing point, and the ice developed mainly from the surface (krell et al. 2003; pantyulin 2003). the ice was thin during all of the expeditions (thickness 34 57 cm) and often fl ooded with seawater. granular snow ice dominated the entire ice column at all times in the white sea. only in march 2001 and in february 2003 was columnar ice observed in the middle part of the ice cores. the sea ice structure was determined by visual observation of the ice core, but was supported by investigation of the crystal structure of thin ice core sections (february and april 2002) (krell et al. 2003). the winter of 2001 was unusually mild and ice formation did not take place until february. the ice was rather porous, granular and white in the upper and in the lowermost parts and columnar and grey in the middle part of the ice cores. the ice was 44 57 cm thick and was covered with a layer of snow which increased in thickness from ca. 10 cm on the fi rst day of the expedition to ca. 16 cm a day later, after a snowfall. below the ice there was a < 1 m thick brackish layer (psu < 15 ‰) with a temperature of –1.2 °c—well above the freezing point. in april 2002 a < 1 m thick brackish layer (psu < 6 ‰, temperature: –1.2 °c) was encountered below the ice; the sea ice below a thin snow cover was granular, white-grey and semi-transparent, and wide channels were observed in the lower 10 cm of ice cores (thickness 34 54 cm). a brownish discolouration was observed at the lowermost surface. in february 2003 the white, dull granular ice was covered with a thick layer of slush (up to 15 cm) and snow (ca. 10 cm). in the middle part, columnar semi-transparent ice was observed. in the lowermost few centimetres, the ice was opaque, white and granular. the water salinity was high (psu 26.1 ‰) and the temperature was –1.2 °c directly beneath the ice (thickness 34 52 cm); both parameters increased with the depth. in april 2003 the depth of the snow cover ranged from 10 to 20 cm on different ice fl oes. the ice fl oes, which remained intact after a storm event, showed no signs of surface melting. however, considerable ice melting occurred from the sides and from below, due to relatively warm water. the lower part of the ice cores (thickness 45 cm) was semi-transparent, granular and had large caverns. the middle part was greyish, opaque and dense. the upper part of the ice layer was not much different from the middle part, though it was softer. in the water column, salinity and temperature varied little from the surface to the bottom. from the north-west part of the gorlo strait (66° 10' n; 40° 10' e), where most of the water is from the barents sea, to the south-east part of the strait (65°40' n; 40°50' e), where white sea water dominates, the temperature increased from –1.52 to –1.08 °c and the salinity decreased from 29.7 ‰ to 27.2 ‰ psu (kosobokova et al. 2004). a peculiar feature of the physical oceanography in the miz of the northern barents sea in july 2001 was a 20 m thick layer of meltwater (–1 to 0.4 °c; psu 31 ‰) above the arctic water (< –1 °c; psu 34 ‰). the ice conditions in the investigated fl oes varied from annual pack ice fl oes (thickness about 1 m) to multi-year pack ice (thickness > 1.35 m). differentiation between the multi-year and annual ice was based mainly on ice thickness and the density of the melosira arctica mats observed by the divers. the snow cover was rather thin (< 10 cm). phytoplankton and sea ice algae: composition a total of 306 algae species (appendix) were identifi ed in the ice, in the water and in the sediment traps. in white sea land-fast ice, 275 species were encountered. the white sea pack ice was inhabited by fewer species (106), and only four of them were not also observed in the land-fast ice. in the barents sea, 201 species were found. in general, the algae composition in the two regions was rather similar: 156 species, including 73 diatoms, 39 dinofl agellates, all silicofl agellates and coccolithophorides and 31 other fl agellates were observed in both regions. the main differences were encountered among the pennate diatoms. in the white sea land-fast ice, 110 pennate species were found, while only 49 and 52 species were found in the white sea and the barents sea pack 98 sea ice algae in the white and barents seas ice, respectively. most of the species were found both in the water column and the ice, but 50 species were not observed in the ice. most of these were benthic ones which only occasionally occurred in the water, but there were also some common planktonic species which were not found in the ice, for example, the diatoms chaetoceros borealis, c. brevis, c. decipiens, corethron criophylum, coscinodiscus centralis, c. radiatus, proboscia eumorpha, rhizosolenia hebetata f. semispina; the dinofl agellates dinophysis contracta, d. arctica, heterocapsa triquetra, protoperidinium pallidum, p. pellucidum, p. pyriforme, warnowia reticulata and a few other fl agellates. some species were observed only in the ice: 37 diatoms (e.g. navicula algida, n. glacialis, n. gelida, nitzshia hybridae, n. polaris, 22 other pennate and 10 centric species) and 7 dinofl agellates (e.g. gymnodinium wulfi i, karenia brevis, protoperidinium granii). diatoms and euglenophytes were represented by more species in the ice (178 and 5, respectively) than in the water (154 and 4, respectively). all other groups were represented by more species in the water; except for chlorophytes, which were represented by the same number of species in the ice and in the water. the snow covering the ice demonstrated poor species diversity (44 species in the snow in comparison to 228 species in the ice). all the species observed in the snow were also found in the underlying ice. the abundance of species also differed between sea ice and the water column: sea ice algae species were less abundant in the water, where plankton species had the higher abundance (appendix). on the basis of morphological and ecological distinctions, some assemblages of the sea ice species were selected for comparison: a) pennate ice plankton species that develop ribbon-shaped colonies (fossula arctica, fragilaria striatula, fragilariopsis spp., pauliella taeniata and some species of navicula and nitzschia—hereafter “ribbon diatoms”); b) single-celled ice-benthic pennate species that sometimes develop barrel-shaped colonies in ice (enthomoneis spp., undatella cf. quadrata, navicula lineola—“barrel diatoms”); c) epiphytic species that are associated with melosira arctica and nitzschia frigida (synedropsis spp., gomphonemopsis cf. exigua, gomphonema septentrionalis, pseudogomphonema kamchaticum and atteya septentrionalis—“associated diatoms”). phytoplankton and sea ice algae: abundance in the white sea land-fast ice, fl agellates dominated the phytoplankton carbon in all samples, but diatoms dominated in the sea ice (table 1). flagellates comprised < 25 % in the ice and 73 80 % in the water (3.8 62 and 0.5 525 mg c m–3, respectively). in february 2003 the species composition and abundance of diatoms and dinofl agellates in the white sea land-fast ice were rather similar to those in the annual ice of the barents sea in july 2001, i.e. centric diatoms dominated in a sparse sea ice algal assemblage (fig. 1). in march 2001 the species composition in the white sea land-fast ice was quite different: barrel and other benthic and ice-benthic diatoms dominated the algae carbon in the ice. benthic singlecelled pennate diatoms were most abundant in the lowermost few centimetres of the ice core on 18 march before a snowfall (> 1 × 105 cells l–1) and in the upper 10 cm of the ice (fig. 2) after the snowfall on 26 march (2.5 × 105 cells l–1). these species were rare in the water, where centric diatoms dominated (fig. 1). in april 2002, nitzschia frigida dominated the total carbon of diatoms and dinofl agellates in the sea ice and water column (fig. 1). two types of white sea pack ice were studied: pack ice fl oes in the southern part of the gorlo strait, probably formed far from the coast (“clean ice”), and fragmented ice in the northern part of the gorlo strait with characteristic brown mineral insertions (“dirty” ice). algae biomass in the “dirty” ice (407 mg с m–3) was close to the highest values in the “clean” ice (87 565 mg с m–3). the composition of the algal populations differed fig 1 (opposite page). composition of the diatoms and dinofl agellates abundance in the lowermost part of the ice, in the upper part of the water column and in sediment traps in the northern barents sea in july 2001 and in the white sea in february 2003, march 2001, april 2002, and in the lowermost part of the ice and in the upper part of the water column in april 2003. “ribbon” denotes plankton diatoms forming ribbon-shaped colonies; “barrel” is benthic single-celled diatoms forming barrel-shaped colonies in the ice; and “associated” stands for species found in association with melosira arctica and nitzschia frigida. each bar represents the value of the single sample in the barents sea and in march 2001 and april 2003 in the white sea. the axes showing biomass are different. each bar is the mean value from the 4 5 samples collected in april 2002 and in february 2003. low biomasses of algae in the white sea in the water in april 2003 and in the traps in february 2003 are indicated by numbers instead of bars. 99ratkova & wassmann 2005: polar research 24(1–2), 95–110 100 sea ice algae in the white and barents seas 101ratkova & wassmann 2005: polar research 24(1–2), 95–110 considerably: pennate ice-planktonic species were dominant in the “clean ice”, while planktonic centric algae were dominant in “dirty” ice (fig. 1). compared to the white sea land-fast ice, pack ice in the white sea had higher concentrations of fl agellates (table 1). sedimentation of algae was low in guba chupa (0.28 2.2 mg c m–2 day–1) and was dominated by plankton centric diatoms in february and march. in april, nitzschia frigida was more abundant than centric diatoms. planktonic centric diatoms dominated the vertical fl ux above the bottom in the deepest part of kandalaksha bay, but the permanent occurrence of sea ice algae, even during the summer months, was remarkable. in contrast to the rather low abundance of phytoplankton below the ice in the white sea, in the barents sea, the biomass of phytoplankton was two orders of magnitude higher than the biomass of sea ice algae (fig. 1). flagellates dominated the sea ice algae and phytoplankton carbon in all samples from the barents sea (table 1). they comprised 60 90 % of the total (1.1 3.9 mg c m–3 in the ice and 30 300 mg c m–3 in the water). in the lowermost part of the annual ice, centric diatoms were abundant (> 50 % of total carbon of diatoms and dinofl agellates). plankton algae dominated the sea ice assemblage and the vertical fl ux in the barents sea. in the water and sediment traps dinofl agellates were the second most abundant group. only one sea ice species (nitzschia frigida) was numerous in the traps. the composition of the sea ice algae population in the multi-year ice was rather similar to that of the sea ice algae in the white sea in april 2002: n. frigida and ribbon diatoms comprised the bulk of the total diatom and dinofl agellate carbon. however, in the water column of the barents sea, total carbon of diatoms was dominated by centric species, whereas in the white sea it was dominated by pennates, n. frigida and ribbon species. total algae concentration was higher in the water than in the ice in the barents sea, but the abundance of melosira arctica and n. frigida was higher in the ice. the sediment trap content under the multi-year ice in the barents sea was rather similar to the algae composition in the ice, in contrast to the traps under the annual ice, where the species m. arctica and n. frigida were sparse. discussion sea ice properties the temperature of the water in the white sea seldom reached the freezing point, and the ice developed mainly from the surface (krell et al. 2003; pantyulin 2003). the ice was thin during all expeditions (range: 34 57 cm) and was often fl ooded by seawater. in the white sea, ice originated mainly from snow: δ18o varied between –1.51 and –8.72 (krell et al. 2003). the granular snow ice dominated the entire ice column at all times in the white sea. only during the coldest part of the year (march 2001, february 2002 and february 2003) was columnar ice observed in the lowermost layer of the ice. congelation ice may only be found during the fi rst stages of ice development in the white sea (melnikov et al. in press). the ice melted from below because the under-ice water temperature never dropped below –1.5 °c in the course of our investigations. the snow removed the bulk salinity from the brine channels and reduced the total sea ice salinity to psu 0 4 ‰. thick snow cover insulated the ice from the cold air, and the temperature in the ice was rather high (> –2 °c). low salinity and the high temperature of the ice led to wide brine channels and low salinity in the brine water (melnikov et al. in press). there are no data regarding the sea ice structure in the investigated region of the barents sea. however, it is well known that congelation ice dominates the total ice column in the barents sea, as in other arctic areas. only the uppermost 10 cm may be represented by snow ice. salinity of the brine water may be as high as psu 70 144 ‰ (gradinger et al. 1999). in summer, the total salinity and temperature of the lowermost part of the ice (psu 3 5 ‰ and –1.2 oc) appear to be comparable with the white sea ice. fig 2 (opposite page). vertical distribution of the sea ice diatoms in the white sea in march 2001, april 2002 and february 2003. “barrel” refers to benthic single-celled diatoms forming barrel-shaped colonies in the ice; “ribbon” is plankton diatoms forming ribbon-shaped colonies. the axes are the same within each column, but the left and right columns have different axes. each bar represents a single sample. 102 sea ice algae in the white and barents seas composition and abundance most of the species that were observed in the sea ice were similar to those recorded from other parts in the arctic. in the high latitude arctic this similarity may be attributed to the long-range transport of ice (von quillfeldt et al. 2003), but this explanation does not hold for the white sea ice. the similarity between sea ice assemblages in the white sea and in other ice-covered regions may be explained by a similar origin of the ice fl ora in all arctic regions (sazhin et al. 2004). three types of sea ice organisms can be distinguished: ice specialists, ice-benthic and ice-plankton species. additionally, plankton and benthic species may also be observed in sea ice. the sea ice specialists were neither observed in bottom sediments nor in plankton in summer, but they were found in the bottom water sediment trap, probably due to resuspension and stirring up of the sediment. as soon as the ice melted, sea ice specialists decayed or developed resting spores (e.g. undatella cf. quadrata, melosira arctica). closely related to these species were ice-benthic species (e.g. diploneis litoralis, enthomoneis spp., navicula lineola), but these species were also observed in bottom sediments as active cells (gogorev 1998). benthic species may be included into the sea ice during its formation in shallow estuaries or bays. they may survive in the ice, but in contrast to the ice-benthic species, their abundance is not high (e.g. mastogloia spp., pinnularia spp., triblionella litoralis). most of these ice-benthic and benthic species were observed in the white sea bottom sediments in march 2001 (f. sapozhnikov, pers. comm.) and in the plankton in the pechora sea during the ice formation in november 2003 (t. ratkova, unpubl. data). these species were observed in the bottom water trap in the white sea deep throughout the year (t. ratkova, unpubl. data). ice-benthic species were not abundant in pack ice, probably because they cannot recolonize ice from the bottom in deeper waters. the sea ice algae that inhabit the pack ice survive the summer in the water column (ice-plankton algae) or in the multi-year ice (sea ice specialists). the ice-plankton species were frequent in land-fast and pack ice (e.g. ribbon diatoms and nitzschia frigida, accompanied with atteya septentrionalis, synedropsis hyperborea and gomphonema-like species). the plankton centric diatom species may be incorporated into the ice during ice formation and during fl ood events (buck et al. 1998). however, they were not abundant in the interior of the ice, but only in the upper and lower layers, where the ice is in contact with the underlying water or fl oodwater. centric diatoms are regarded as allochthonous for the ice realm. thus, pennate diatoms dominate among the sea ice algae from the chukchi, east siberian and laptev seas (okolodkov 1992). the lower part of the annual sea ice in the northern barents sea was dominated by ice-plankton and plankton diatoms. the sub-ice assemblage was dominated by ice-plankton (ribbon diatoms and nitzschia frigida). the ice specialist melosira arctica, the icebenthic species (enthomoneis spp., diploneis litoralis) and associated species were also observed. planktonic algae dominated the water and sediment traps. only one sea ice species (n. frigida) was numerous in the traps. the sea ice community of the annual ice in the northern barents sea included more planktonic algae than in the white sea, but the same benthic species occurred in both areas. the diatom population in the lower part of the multi-year ice was dominated by ribbon diatoms and by n. frigida. m. arctica developed into thick mats below the ice. the plankton diatom chaetoceros socialis dominated the water below the ice, but in the upper few metres m. arctica was also abundant. m. arctica was abundant in the sediment traps below the multi-year ice, in contrast to those below annual ice, indicating that this species is primarily introduced to the barents sea from the arctic ocean. many resting spores of m. arctica were observed in the water column and in sediment traps. evidently, part of the m. arctica mats were detached from the lower surface of the ice. coastal sea ice of the white sea forms in productive systems where a continuous nutrient supply from the water column (rivers, sediment, mixing by tidal currents) sustains high algal biomass, with diatoms as the dominating taxon (krell et al. 2003). oceanic ice habitats of the barents sea, however, are characterized by more regenerative food webs, with lower biomass and a higher contribution of fl agellates (gradinger 1999). this illustrates the main difference between the white sea land-fast ice and white and barents seas pack ice. these two different scenarios contribute to the observed differences in composition and abundance of the ice algae in these two types of sea ice. 103ratkova & wassmann 2005: polar research 24(1–2), 95–110 the difference between the abundance of sea ice algae in the white sea and in the barents sea may be attributed in part to the different timing of growth. in the northern barents sea the productivity of sea ice algae is highest in july (kuznetsov & schoschina 2003), but in the white sea it is in april (ilyash et al. 2003). our observations in the barents sea were conducted at the end of sea ice algae vegetation and before and during the maximum of sea ice algae development in the white sea. the species composition in the ice changes little with the age of the ice, whereas the relative abundance of each species may change markedly: plankton species, which are more abundant and dominate total algae numbers and carbon in young ice, may be replaced by ice species, which are more abundant in older ice. the composition of the sea ice algae results primarily from the composition of algae in the underlying water masses in regions that are not ice-covered during a part of the year, or from the composition of the sea ice algae community in the ice-edge or in polynyas (syvertsen 1991; weissenberger 1998; druzhkov et al. 2001). in shallow water areas benthic algae may also be included in the succession cycles (poulin 1990; gogorev 1998). the stickiness of pennate diatoms (riebesell et al. 1991) may partially explain their high enrichment rates. usually the planktonic and benthic algae entrapped by the ice crystals in autumn (syvertsen 1991; melni kov 1997; von quillfeldt 1997) will be sparse during the entire winter. they start their development in spring (zhitina & mikhailovsky 1990). however, if sea ice forms earlier (in october in the northern barents sea), the entrapped algae may develop immediately (horner 1990; druzhkov et al. 2001), overwintering as a well-organized community. the timing of the development of the sea ice algae community can be explained mainly by the light conditions and the taxonomic composition of the algae: benthic algae may be better adapted to lower irradiance and lower temperature than planktonic ones (gogorev 1998). the vertical distribution of sea ice algae the benthic algae entrapped by the ice crystals during ice formation in february 2001 may have developed immediately in the lower part of the thin granular ice because the light conditions in newly formed ice are favourable for algae growth. when the irradiance decreased after a heavy snowfall, they may have actively moved through the brine channels to the upper part of the ice. consequently, on 26 march 2001 the highest biomass of these species was observed in the upper 10 cm of the ice. the same vertical distribution was also observed in february 2003, when the snow cover was exceptionally thick. the ice-planktonic and ice-benthic species may demonstrate new morphological peculiarities when they live in ice. some of the species became longer (fragilariopsis cylindrus, f. oceanica, nitzschia longissima); others (enthomoneis spp, undatella cf. quadrata and navicula lineola) developed large barrel-like colonies. these morphological changes may indicate an adaptation to new conditions. in march 2001 we also observed an upward movement of the ice-benthic diatom diploneis litoralis. it had its highest abundance in the lower 5 cm of the ice core on 18 march and was displaced to the upper 10 cm by 22–26 march. we speculate that the vertical species succession, which usually occurs over a time span of months (syvertsen 1991), took place in a week in 2001 because of the late development of the sea ice. conclusion a total of 306 algae species were identifi ed in ice, water and sediment traps in the barents and white seas. in the white sea land-fast ice, 275 species were recorded. in the white sea pack ice, species were less numerous (106 species), and only four of these species were not observed in the land-fast ice. in the barents sea, 201 species were found. in general, the algae composition in the two regions was rather similar. the main differences were encountered among the pennate diatoms: in the white sea land-fast ice, 110 pennate species were found, while only 49 and 52 species were found in the white sea and barents sea pack ice, respectively. most of the species were found both in the water column and in the ice, but a few species were not observed in the ice. the algae communities of the ice and ice-covered waters in the white and barents seas are highly variable in space and time (sazhin et al. 2004; von quillfeldt et al. 2003). to understand the dynamics of these algae assemblages, one must take into account the formation history of the ice. the algae communities of the land-fast ice, dominated by pennate diatoms, are more closely related to the bottom sediments than the commu104 sea ice algae in the white and barents seas nity of the pack ice, which is dominated by centric diatoms. the algae in the land-fast ice community are more numerous and variable than those of the pack ice. motile benthic and ice-benthic species fi nd favourable conditions in the ice because of the close proximity and similarity between the bottom sediments and the sea ice interior (gogorev 1998). the plankton and ice-plankton species fi nd stable illumination and refuge from grazers in the ice. however, conditions here are less favourable for plankton algae, which are welladapted to life in the water column, where algae circulate passively with the turbulent fl ow and where conditions for nutrient uptake are better. algae living in ice, in contrast, must contend with the laminar fl ow in the narrow channels of the ice, where the nutrient supply in the upper layer may be very low (gradinger & ikävalko 1998). benthic and ice-benthic ice algae are better adapted to such conditions, attaching themselves to the substrates or actively moving along the walls of the channels. the pack ice community is related to that in the surrounding water. it originates from it and is released into it after the ice melt. an additional source for ice algae colonization may be the multi-year ice. algae may be released from the ice during warming events, because of the brine drainage, or during the sea ice melting. some of the sea ice algae develop spores before the ice melt. these spores may be transported to other ice fl oes, or sink down to the bottom of shelf regions until the next season. grazers may quickly ingest the released algae: in the white sea almost none of the released diatoms reach the bottom. the sedimentation rate of the algae is therefore extremely low and a high rate of faecal pellet export was observed (kosobokova et al. 2003). acknowledgements.—we are grateful to e. arashkevich for general discussions and to two anonymous referees for reading and commenting on the manuscript. the technical assistance of e. halttunen, k. riser, j. søreide, a. belov and a. novigatsky is gratefully acknowledged. this work was supported by: the european union, contract no. evk3-ct-2000-00024, funding the project food web uptake of persistent organic pollutants in the arctic marginal ice zone of the barents sea (famiz); the russian foundation for basic research, contract no. 02-05-65059; inco-copernicus, contract no. ica2-ct-2000-10053; the nordic arctic research program’s project production, food-web dynamics and biological origin of compounds involved in aerosol formation; and the norwegian research council, which supported the project carbon flux and ecosystem feedback in the northern barents sea in an era of climate change (cabanera). references buck, k. r., nielsen, t. g., hansen, b. w., gastrup-hansen, d. & thomsen, h. a. 1998: infi ltration phytoand protozooplankton assemblages in the annual sea ice of disco island, west greenland, spring 1996. polar biol. 20, 377–381. druzhkov, n. v., druzhkova, e. i., larionov, v. v. & turakov, a. b. 2001: sostav i vertikalnoe raspredelenie ledovoi mikrobioty v severnoy chasti barentzeva morja v nachale zimnego perioda 1998 (1). (the composition and vertical distribution of the ice algae communities in the northern barents sea at the beginning of the winter 1998 [1].) in a. p. lisitzin & m. e. vinogradov (eds.): opyt systemnykh okeanologicheskikh issledovanyi v arktike (experience of system oceanologic studies in the arctic). pp. 325– 343. moscow: scientifi c world publ. gogorev, r. m. 1998: dyatomovye pozdne-vesennego l’da v belom more (bacillariophyta glaciei veris seri maris albi). (diatoms of the late spring ice of the white sea.) novosti systematiki nizshikh rasteny (novitates systematicae plantarum non vascularium) 32, 8–13. gradinger, r. 1999: vertical fi ne structure of the biomass and composition of algal communities in arctic pack ice. mar. biol. 133, 745–754. gradinger, r., friedrich, c. & spindler, m. 1999: abundance, biomass and composition of the sea ice biota of the greenland sea pack ice. deep-sea res. ii 46, 1457–1472. gradinger, r. & ikävalko, j. 1998: organisms incorporation into the newly forming arctic sea ice in the greenland sea. j. plankton res. 20, 871–886. hendey, n. i. 1964: an introductory account of the smaller algae of british coastal waters. part y: bacillariophyceae (diatoms). london: her majesty’s stationery offi ce. horner, r. a. 1985: sea ice biota. boca raton, fl: crc press. horner, r. a. 1990: ice-associated ecosystems. in l. k. medlin & j. priddle (eds.): polar marine diatoms. pp. 9–14. cambridge: british antarctic survey, natural environment research council. ilyash, l. v., zhitina, l. c. & fedorov, v. d. 2003: phytoplankton belogo morja. (phytoplankton of the white sea.) moscow: janus-k. publ. konovalova, h. v. 1998: dinofl agellates (dinophyta) dal’nevostochnykh morye rossii i sopredelnykh akvatoriy tikhogo okeana. (dinofl agellatae [dinophyta] of the far eastern seas of russia and adjacent waters of the pacifi c ocean). vladivostok: dalnauka. kosobokova, k. n., pantyulin, a. n., rachor, e., ratkova, t. n., shevchenko, v. p., agatova, a. i., lapina, n. m. & belov, a. a. 2004: complex oceanographic studies in deep-water part of the white sea in the end of winter 2003. oceanology 44, 313–320. kosobokova, k. n., ratkova, t. n. & sazhin, a. f. 2003: early spring zooplankton in the ice-covered chupa inlet (white sea), 2002. oceanology 43, 734–743. krell, a., ummenhofer, c., kattner, g., naumov, a., evans, d., dieckmann, g. s. & thomas, d. n. 2003: the biology and chemistry of land fast ice in the white sea, russia — a comparison of winter and spring conditions. polar biol. 26, 707–719. krishtofovich, a. n. & proshkina-lavrenko, a. i. (eds.) 1949: diatomovyi analys. opredelitel iskopaemykh and sovremennykh diatomovykh vodorosley. (analysis of diatoms. guide to fossil and recent diatoms.) vol. 2. central105ratkova & wassmann 2005: polar research 24(1–2), 95–110 es and mediales. leningrad: state publisher of geological literature. krishtofovich, a. n. & proshkina-lavrenko, a. i. (eds.) 1950: diatomovyi analys. opredelitel iskopaemykh and sovremennykh diatomovykh vodorosley. (analysis of diatoms. guide to fossil and recent diatoms.) vol. 3. pennales. leningrad: state publisher of geological literature. kuznetsov, l. l. & schoschina, e. v. 2003: phytocenosy barentzeva morja (phisiologicheskie i strukturnye kharakteristiki). (phytocenoses of the barents sea [physiological and structural characteristics].) apatity: kola scientifi c centre ras. lizotte, m. p. 2003: the microbioligy of sea ice. in d. n. tomas & g. s. dieckmann (eds.): sea ice: an introduction to the physics, chemistry, biology and geology. pp. 184– 210. oxford: blackwell. medlin, l. k. & priddle, j. (eds.) 1991: polar marine diatoms. cambridge: british antarctic survey. melnikov, i. a. 1997: the arctic sea ice ecosystem. amsterdam: gordon and breach scientifi c publishers. melnikov, i. a., dikarev, s. n., kolosova, e. g. & zhitina, l. s. in press: functional peculiarities of the coastal ice ecosystem in the zone of sea–river interaction. oceanology 45. menden-deuer, s. & lessard, e. j. 2000: carbon to volume relationship for dinofl agellates, diatoms and other protists plankton. limnol. oceanogr. 45, 569–579. okolodkov, y. b. 1992: cryopelagic fl ora of the chukchi, east siberian and laptev seas. proceedings of the national institute of polar research symposium on polar biology 5, 28–43. okolodkov, y. b. 1998: a checklist of dinofl agellates recorded from the russian arctic seas. sarsia 83, 267–292. pantyulin, a. n. 2003: hydrological system of the white sea. oceanology 43, suppl. 1, s1–s14. poulin, m. 1990: ice diatoms: the arctic. in l. k. med lin & j. priddle (eds.): polar marine diatoms. pp. 15–18. cambridge: british antarctic survey, natural environment research council. ratkova, t. n. & wassmann, p. 2002: seasonal variation and spatial distribution of phytoand protozooplankton in the central barents sea. j. mar. syst. 38, 47–75. riebesell, u., schloss, i. & smetacek, v. 1991: aggregation of algae released from melting ice: implication for seeding and sedimentation. polar biol. 11, 239–248. sazhin, a. f., rat’kova, t. n. & kosobokova, k. n. 2004: inhabitants of coastal ice of white sea in early spring period. oceanology 44, 92-100. sazhin, a. f., rat’kova, t. n. & kosobokova, k. n. in press: inhabitants of coastal ice of white sea in late winter period. oceanology. semina, h. i. 1974: phytoplankton tichogo okeana. (pacifi c phytoplankton.) moscow: nauka. semina, h. i. & sergeeva, o. m. 1983: planktonnaja fl ora i biogeographicheskie kharakteristiki phytoplanktona belogo morja. (plankton fl ora and biogeographical characteristics of the phytoplankton of the white sea.) trudy belomorskoy biologicheskoy stanzii mgu 6, 3–17. snoeijs, p. (ed.) 1993: intercalibration and distribution of diatoms species in the barents sea 1993. vol. 1. baltic marine biologists publications 16a. uppsala: opulus press. snoeijs, p. & vilbaste, s. (eds.) 1994: intercalibration and distribution of diatoms species in the barents sea. vol. 2. baltic marine biologists publications 16b. uppsala: opulus press. snoeijs, p. & potapova, m. (eds.) 1995: intercalibration and distribution of diatoms species in the barents sea. vol. 3. baltic marine biologists publications 16c. uppsala: opulus press. snoeijs, p. & kasperovičienė, j. (eds.) 1996: intercalibration and distribution of diatoms species in the barents sea. vol. 4. baltic marine biologists publications 16d. uppsala: opulus press. snoeijs, p. & balashova, n. (eds.) 1998: intercalibration and distribution of diatoms species in the barents sea. vol. 5. baltic marine biologists publications 16e. uppsala: opulus press. strathmann, r. r. 1967: estimating the organic carbon content of phytoplankton from cell volume or plasma volume. limnol. oceanogr. 12, 411–418. syvertsen, e. e. 1991: ice algae in the barents sea: types of assemblages, origin, fate and role in the ice-edge phytoplankton bloom. in e. sakshaug et al. (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, norway, 12-16 may 1990. polar res. 10, 277–287.. thomsen, h. a. (ed.) 1992: plankton i de indre danske farvande. (plankton in the inner danish waters.) havforskning fra miljøstyrelsen 11. copenhagen. throndsen, j., hasle, g. r. & tangen, k. 2003: norsk kystplankton fl ora. (norwegian coastal phytoplankton.) oslo: almater forlag. tomas, c. r. 1997: identifying marine phytoplankton. london: academic press. tuschling, k. 2000: zur oekologie des phytoplanktons im arktischen laptevmeer—ein jahreszeitlicher vergleich. (phytoplankton ecology in the arctic laptev sea—a comparison of three seasons.) ber. polarforsch. 347. ulanova, a. a. 2003: vodorosli vodoemov s nestabil’noy solenostju poberezhii belogo morja i murmanskogo poberezhja barenzeva morja. (algae from water bodies with unstable salinity in the white sea and murmansk area of the barents sea coastal zone). candidate of biology thesis. saint petersburg state university. von quillfeldt, c. h. 1996: ice algae and phytoplankton in north norwegian and arctic waters: species composition, succession and distribution. d. sc. thesis, university of tromsø. von quillfeldt, c. h. 1997: distribution of diatoms in the north-east water polynya, greenland. j. mar. syst. 10, 211–240. von quillfeldt, c. h. 2000: common diatom species in arctic spring blooms: their distribution and abundance. bot. mar. 43, 499–516. von quillfeldt, c. h., ambrose jr., w. g. & clough, l. m. 2003: high numbers of diatom species in fi rst-year ice from the chukchi sea. polar biol. 26, 806–818. weissenberger, j. 1998: arctic sea ice biota: design and evaluation of a mesocosm experiment. polar biol. 19, 151–159. weissenberger, j. & grossmann, s. 1998: experimental formation of sea ice: importance of water circulation and wave action for incorporation of phytoplankton and bacteria. polar biol. 20, 178–188. zhitina, l. s. & mikhailovskyi, g. e. 1990: ledovaja i planktonnaja fl ora belogo morja kak ob’ekt monitoringa. (ice and plankton fl ora of the white sea as a subject of monitoring.) in: biologicheskiy monitoring pribregnykh vod belogo morya. (biological monitoring of the inshore waters of the white sea.) pp 41–49. moscow: institute of oceanology of the ussr academy of sciences. 106 sea ice algae in the white and barents seas appendix the following table indicates the relative abundance, geographic ranges and ecology of the species recorded from ice cores and sub-ice water in the white sea in february, march and april 2001– 03 and in the barents sea in july 2001. (identifi cations are based on krishtofovich & proshkinalavrenko [1949, 1950], hendey [1964], semina [1974], semina & sergeeva [1983], medlin & priddle [1991], thomsen [1992], snoeijs [1993], snoeijs & vilbaste [1994], snoeijs & potapova [1995], snoeijs & kasperovičienė [1996], von quillfeldt [1996, 2000], konovalova [1997], tomas [1997], okolodkov [1998], snoeijs & balashova [1998], tuschling [2000], ulanova [2003], throndsen et al. [2003] and von quillfeldt et al. [2003].) geographic ranges (in the column headed “range”) are: cosmopolitan (c), arctic–boreal (ab), bipolar (b), tropical–arctic–boreal (tab), tropical– boreal (tb) and tropical (t). ecological categories (“ecology”) are: freshwater (f), brackish water (b), marine (m), eurihaline (e), neritic (n), ice– neritic (in), marine–neritic (mn), epiphytic (ep) and benthic (be). relative abundance (mean number of cells for all available samples) categories are: 1 (< 1 104), 2 (1 104 1 105), 3 (1 105 1 106) and 4 (> 1 106 cells l–1. abundance white sea bar. sea c el l v ol . (m µ3 ) r an ge e co lo gy ic e sn ow w at er ic e w at er division chromophyta class bacillariophyceae achnanthes brevipes agardh 4000 c b, be 1 1 a. fl exella (kütz.) brun 9000 f, be 1 achnantidium minutissima (kütz.) czarm. 250 f, be 1 1 actinocyclus curvatulus ehrenberg 67 500 c m 1 1 a. octonarius ehrenberg 48 000 c m 1 amphora spp. 1 1 1 asterionella formosa hassal 800 c f 1 attheya septentrionalis (øestrup) crawford 150 ab m, ep, in 3 2 1 3 1 bacterosira bathyomphala (gran) syvertsen & hasle 2200 ab m, n 1 1 1 caloneis sp. 1 campylodiscus fastuosus ehrenberg 42 000 ab? m, be 1 chaetoceros affi nis lauder 4600 ab? m, n 1 1 c. borealis bailey 11 250 tab m 1 c. brevis schütt 1500 ab m, n 1 c. ceratosporus ostenfeld 50 ab m, n 2 1 2 c. compressus lauder 600 tab m 1 1 1 c. concavicornis mangin 2200 ab m 1 1 c. danicus cleve 7500 tab b, n 1 1 c. debilis cleve 600 tab m, n 1 1 1 c. decipiens cleve 13 500 c m 1 1 c. diadema (ehrenberg) gran 3100 ab m, n 1 1 1 c. diversum cleve 720 tb m, n 1 c. fallax proshkina-lavrenko 1100 1 c. furcellatus bailey 200 ab m, n 1 1 1 c. gracilis schütt 110 ab m, n 1 1 1 1 c. holsaticus schütt 720 ab b, n 1 c. invisibilis gogorev 30 m, in 2 1 3 c. laciniosus schütt 400 tab m, n 1 1 1 c. perpusillus cleve 300 tab m, n 1 c. similis cleve 300 ab m, n 1 c. simplex ostenfeld 350 tab e, n 1 3 1 1 c. socialis lauder 100 c e, n 2 3 3 3 3 c. wighamii brightwell 600 ab e, n 1 cocconeis costata gregory 4600 ab? m, n 1 1 c. pediculus ehrenberg 1440 b, ep 1 c. scutellum ehrenberg 9000 c? m, n 1 1 c. stauroneiformis (van heurck) okuno 4050 b, ep 1 1 corethron criophyllum castracane 25 200 c m 1 coscinodiscus asterom phalus ehrenberg 1012 500 c m 1 1 c. centralis ehrenberg 844 000 c m 1 c. concinnus w.smith 1350 000 c m 1 1 c. radiatus ehrenberg 42 300 c m 1 ctenophora pulchella (ralfs & kützing) williams & round 6370 ab e, be 1 1 1 cyclotella choctawhatcheana (proshkina-lavrenko) prasad 1700 ab e, n 1 1 1 c. litoralis lange & syvertsen 16 000 b e, n 1 1 c. striata (kützing) grunow 3000 ab? e, n 1 1 cylindropyxis tremulans hendey 140 1 1 cylindrotheca closterium (ehrenberg) lewin & reimann 450 c e, n 1 1 1 1 1 abundance white sea bar. sea c el l v ol . (m µ3 ) r an ge e co lo gy ic e sn ow w at er ic e w at er table continued from previous column. 107ratkova & wassmann 2005: polar research 24(1–2), 95–110 dactyliosolen fragilissimus (bergon) hasle 5100 c? 1 detonula confervacea (cleve) gran 270 ab m, n 1 1 diatoma tenuis agardh 800 f 1 1 didymosphaenia geminata (lyngb.) m.schmidt 56 900 f, be 1 diploneis didyma (ehrenberg) ehrenberg 10 000 ab? b, n 1 1 d. litoralis var. litoralis (øestrup) cleve 2300 ab m, n 2 1 1 1 d. litoralis var. arctica (øestrup) cleve 2700 ab m, in 1 d. litoralis var. clathrata (øestrup) cleve 5300 ab m, in 1 1 ditylum brightwellii (west) grunow 11 800 tb m 1 1 1 entomoneis alata (ehrenberg) poulin & cardinal 3000 1 1 1 1 e. kjelmanii (cleve in cleve & grunow) poulin & cardinal 78 000 ab m, in 1 1 1 e. kjelmanii var. subtilis (grunow) poulin & cardinal 16 000 ab m, in 1 1 e. paludosa (w. smith) poulin & cardinal 28 800 ab b, in 1 1 1 e. paludosa var. hyperborea (grunow in cleve & grunow) poulin & cardinal 29 400 ab m, in 1 1 e. pseudopulex osada & kobayasi 23 600 1 e. punctulata (grunow) osada & kobayasi 18 700 ab b, in 1 1 1 entomoneis sp. 25 200 1 1 eucampia groenlandica cleve 1500 ab m, n 1 1 1 fallacia forcipata (greville) stickle & mann 23 520 c m 1 1 fossula arctica hasle, syvertsen & von quillfeldt 1400 ab m, in 2 1 1 3 1 fragilaria striatula lyngbye 2560 ab m, in 2 1 1 1 f. ulna (nitzsch) lange-bertalot 7300 f 1 1 fragilariopsis cylindrus (grunow) krieger 100 b m, in 2 1 1 2 1 f. oceanica (cleve) hasle 400 ab m, in 2 1 1 1 1 gomphonemopsis cf. exigua (simonsen) medlin 1920 ab? m, ep, in 2 1 1 1 1 grammatophora arctica cleve 12000 ab? m, n 1 1 g. oceanica (ehrenberg) grunow 9000 ab? m, n 1 guinardia delicatula (cleve) hasle 7000 c m, n 1 1 gyrosigma compactum greville 4300 1 1 1 g. fasciola var. tenuirostris (grunow) cleve 7000 ab? m, n 1 g . hudsonii poulin & cardinal 18 000 ab m, in 1 1 g. tenuissimum var. hyperborea (grunow) cleve 3400 m, n 1 1 1 hannaea arcus (ehrenberg) patrick 3200 f 1 hantzschia sp. 1 1 haslea sp. 1 1 lauderia annulata cleve 22 800 tb m 1 1 1 leptocylindrus danicus cleve 1200 tab? m, n 1 1 1 l. minimus gran 600 tab m 1 1 licmophora communis (heiberg) grunow 4100 ab? m, n 1 1 l. gracilis (ehrenberg) grunow 18 200 m, n 1 1 mastogloia sp. 1 1 1 melosira arctica dickie 1500 ab m, in 1 1 2 1 m. moniliformis (o.f.müller) agardh 25 200 b, n 1 m. nummuloides agardh 43 500 c m, n 1 1 melosira sp. 1 meridion circularis (grev.) agardh 400 f 1 meuniera membranacea (cleve) p.c. silva 15 000 ab 1 navicula algida grunow 120 000 ab m, in 1 n. directa (w.smith) ralfs 9000 ab 1 1 n. distans (w.smith) ralfs 56 300 ab? be 1 1 n. gelida grunow 15 000 ab m, in 1 n. glacialis cleve 7300 ab m, in 1 n. granii (jørgensen) gran 2700 ab m, in 2 1 1 n. cf. lineola grunow 9050 ab m, in 1 1 1 n. menisculus var. meniscus (schum.) hust. 2200 f 1 n. microcephala grunow 540 f 1 n. monilifera cleve 10 000 ab? m 1 n. pelagica cleve 1100 ab e, n 2 1 2 1 n. pellucidula hustedt 7200 ab m, in 1 n. septentrionalis (grunow) gran 800 ab m, n 1 1 n. superba cleve 9600 ab m, in 1 n. transitans var. derasa (grunow) cleve 34 900 ab 1 1 n. vanhoeffenii gran 2200 ab e, n 1 1 nitzschia angularis w.smith 3200 1 n. dissipata (kützing) grunow 2250 f 1 abundance white sea bar. sea c el l v ol . (m µ3 ) r an ge e co lo gy ic e sn ow w at er ic e w at er abundance white sea bar. sea c el l v ol . (m µ3 ) r an ge e co lo gy ic e sn ow w at er ic e w at er table continued from previous column. table continued from previous column. 108 sea ice algae in the white and barents seas n. frigida grunow 4500 ab m, in 4 1 1 3 1 n. hybrida grunow 2400 ab b, in 1 n. longissima (brebisson) ralfs 830 b m, n 1 1 1 1 n. neofrigida medlin 19 000 ab m, in 1 1 1 n. pellucida grunow 1100 ab? b 1 n. polaris grunow 6500 ab m, in 1 n. promare medlin 560 ab m, in 2 1 1 1 n. recta hantzsch. 1400 f 1 n. scrabra cleve 12 000 ab m 1 1 1 n. sigmoidea (ehrenberg) wm. smith 9000 b 1 1 1 odontella aurita agardh 10 500 c? b, n 1 1 1 paralia sulcata (ehrenberg) cleve 3300 c? m, be 1 1 1 pauliella taeniata (grunow) round et basson 1000 ab e, mn 2 1 1 3 1 pinnularia guadrataera var. baltica grun 15 000 tab m, n 1 1 p. semiinfl ata (øestrup) gran 5400 ab m, in 1 plagiotropis lepidoptera (gregory) poulin & cardinal 60 000 tab m, n 1 1 p. scaligera grunow in cleve & grunow 10 000 1 1 1 planotidium delicatulum (kützing) round & bukht. 200 ab? e, n 1 pleurosigma angulatum (quekett) wm.smith 6000 tab? b, n 1 1 1 1 p. clevei grunow in cleve & grunow 35 000 ab m, in 1 1 1 p. fi nmarchicum cleve & grunow 67 500 ab? mn 1 1 1 p. formosum wm.smith 18 700 1 1 p. normanii ralfs 4500 c? 1 1 1 1 porosira glacialis (grunow) jørgensen 38 800 b n 1 1 1 1 proboscia eumorpha (castracane) takahashi, jordan & priddle 3200 c m, mn 1 pseudogomphonema kamtchaticum (grunow) medlin 7200 ep 1 1 2 p. septentrionale (øestrup) medlin 3200 ab? m, ep, in 1 pseudo-nitzschia australis (cleve) heiden 3100 tb m, mn 1 1 1 p. calliantha (hasle) lundholm, moestrup & hasle 100 ab m, mn 1 1 1 p. delicatissima (cleve) heiden 200 ab m, mn 1 1 p. granii (hasle) hasle 30 ab? 1 1 1 p. pungens (grunow & cleve) hasle 1400 c m, mn 1 p. seriata (hasle) hasle 3200 ab m, mn 1 p. seriata f. obtusa (hasle) hasle 2200 ab 1 1 rhabdonema arcuatum (lyngbye) kützing 49 500 ab ep 1 1 rhizosolenia hebetata f. semispina (hensen) gran 37 500 ab m, mn 1 rhizosolenia setigera brightwell 18 000 c m, mn 1 rhoicosphenia curvata (kützing) grunow 4000 b, n 1 1 skeletonema costatum (greville) cleve 200 c m, mn 2 1 1 2 1 stauroneis amphioxys gregory 24 000 ab? n 1 stenoneis sp. 1 synedropsis hyperborea (grunow) hasle, medlin & syvertsen 270 ab m, in 2 1 2 1 synedropsis hypeboreoides hasle, medlin & syvertsen 250 ab m, in 1 1 1 tabellaria binalis (ehrenberg) grunow 4800 f 1 1 t. fenestrata (lyngbye) kützing 30 000 f 1 1 1 t. fl occulosa (roth.) kützing 18 700 f 1 1 thalassionema nitzschioides (grunow) grunow & hustedt 400 tab m, mn 1 1 1 thalassiosira angulata (gregory) hasle 4300 ab m, mn 1 1 1 1 1 t. anguste-lineata (a.schmidt) fryxell & hasle 12 000 tab m, n 1 1 1 t. antarctica var. borealis fryxell, douc. & hubb. 14 580 ab m, mn 1 1 1 1 1 t. bioculata (grunow) ostenfeld 18 000 ab? 1 t. bulbosa syvertsen 400 ab 1 1 1 t. conferta hasle 2000 tb 2 1 1 t. eccentrica (ehrenberg) cleve 23 400 tab e, mn 1 t. gravida cleve 9000 b m, mn 1 1 t. hyalina (grunow) gran 6500 ab m, mn 2 1 1 1 t. hyperborea (grunow) hasle & lange 25 000 ab b, in 1 1 1 1 t. nordenskioeldii cleve 2900 ab e, n 1 1 1 1 1 trachyneis aspera (ehrenberg) cleve 160 000 ab m, n 1 1 tryblionella litoralis (grunow) d.g.mann 18 000 m, be 1 1 1 undatella cf. quadrata (bréb. in kütz.) padd. et sims 24 300 tab? m, be 1 1 1 abundance white sea bar. sea c el l v ol . (m µ3 ) r an ge e co lo gy ic e sn ow w at er ic e w at er abundance white sea bar. sea c el l v ol . (m µ3 ) r an ge e co lo gy ic e sn ow w at er ic e w at er table continued from previous column. table continued from previous column. 109ratkova & wassmann 2005: polar research 24(1–2), 95–110 class dinophyceae alexandrium insuetum balech 1500 tab? n 1 1 1 2 a. ostenfeldii (paulsen) balech & tangen 147 000 tab? n 1 1 a. tamarense (lebour) balech 19 000 tab? n 1 1 1 amylax triacantha (jørgensen) sournia 5000 ab n 1 amphidinium crassum lohmann 2300 ab? n 1 1 1 1 a. fusiformis martin 1050 ab? n 1 1 1 1 a. larvale lindemann 190 e, n 1 1 1 a. latum lohmann 1350 ab? n 1 a. longum lohmann 1300 c n 1 1 1 1 a. sphenoides wulff 1100 ab m 1 1 1 ceratium fusus (ehrenberg) dujardin 91 800 c m 1 1 c. lineatum (ehrenberg) cleve 46 900 tb m 1 cochlodinium archimedes (pouchet) lemmermann 1400 ab m 1 1 1 1 cochlodinium brandtii wulff 8000 ab mn 1 1 cochlodinium schuetti (kofoid & swezy) shiller 6000 1 1 1 1 dinophysis acuminata claparède & lachmann 19 000 c n 1 d. acuta ehrenberg 18 000 b m 1 d. arctica mereschkowsky 9000 b n 1 d. contracta (kofoid & skogsberg) balech 6000 tab m 1 d. islandica paulsen 36 000 ab n 1 d. norvegica claparède & lachmann 35 000 ab n 1 1 diplopelta parva (abé) matsuoka 5900 ab n 1 1 1 enthomosigma peridinioides shiller 1200 tab? n 1 1 1 glenodinium gymnodinium penard 50 000 b, n 1 gonyaulax digitalis (pouchet) kofoid 40 000 b mn 1 g. grindleyi reinecke 18 000 ab n 1 1 1 g. spinifera (claparède & lachmann) diesing 9900 c mn 1 1 gymnodinium albulum lindermann 150 b, n 1 1 1 1 2 g. arcticum wulff 4000 ab mn 1 1 1 g. blax harris 260 f 1 1 g. frigidum balech 13 500 b n 1 1 g. japonica hada 400 n 1 1 1 1 g. heterostriatum kofoid & swezy 4700 tab? n 1 g. lebourii pavillard 108 000 1 1 g. simplex (lohmann) kofoid & swezy 190 tab n 1 1 1 g. wulfi i schiller 4000 tab n 1 gyrodinium cf. aureolum hulburt 24 000 ab 1 1 1 g. cohnii (seligo) schiller 4500 ab? 1 g. esturiale hulburt 1700 c n 1 g. fusiforme kofoid & swezy 1620 tab mn 1 1 1 1 g. lachryma (meunier) kofoid & swezy 36 700 ab mn 1 1 1 g. prunus (wulff) lebour 47 000 c 1 1 g. spirale (berg) kofoid & swezy 17 000 c 1 1 1 1 heterocapsa rotundatum (lohmann) loeblich 400 c n 1 1 2 h. triquedrum (lohmann) hansen 6900 c b, n 1 karenia brevis (davis) g.hansen & moestrup 4000 ab n 1 karlodinium micrum (leadbeater & dodge) j.larsen 1700 1 1 1 k. venefi cum (ballantine) j.larsen 900 1 1 1 1 1 k. vitiligo (ballantine) j.larsen 1700 1 1 1 1 1 katodinium glaucum (lebour) loeblich 2100 tab n 1 1 1 micracanthodinium claytonii (holmes) dodge 3800 1 oblea baculifera balech 1700 b 1 1 oxyrrhis marina dujardin 6500 tab? e, n 1 oxytoxum belgicum meunier 5250 1 peridinella catenata (lev.) balech 4700 ab n 1 1 1 preperidinium meunieri (pavillard) elbrächter 10 000 t m 1 1 1 pronoctiluca acuta (lohmann) schiller 1600 tab mn 1 p. pelagica fabre-domergue 9400 c m 1 1 prorocentrum balticum (lohmann) loeblich 400 c m 1 1 1 1 p. cordatum (ostefeld) dodge 1600 tab n 1 1 1 p. micans ehrenberg 6000 tab n 1 1 p. minimum (pavillard) schiller 720 c n 1 1 protoperidinium bipes (paulsen) balech 2000 c n 1 1 1 p. brevipes (paulsen) balech 10 100 ab n 1 1 1 p. depressum (bailey) balech 130 000 c m 1 p. granii (ostefeld) balech 66 000 c n 1 1 p. islandicum (paulsen) balech 36 000 ab n 1 abundance white sea bar. sea c el l v ol . (m µ3 ) r an ge e co lo gy ic e sn ow w at er ic e w at er abundance white sea bar. sea c el l v ol . (m µ3 ) r an ge e co lo gy ic e sn ow w at er ic e w at er table continued from previous column. table continued from previous column. 110 sea ice algae in the white and barents seas p. nudum (meunier) balech 9400 ab mn 1 1 p. pallidum (ostenfeld) balech 13 500 b m, n 1 p. pellucidum bergh 51 800 c n 1 1 p. pyriforme subsp. pyriforme (paulsen) balech 24 000 c 1 p. pyriforme subsp. breve (paulsen) balech 23 300 ab? 1 p. subinerme (paulsen) loeblich iii 62 500 c 1 1 scrippsiella trochoidea (stein) loeblich iii 5900 c n 1 1 1 1 1 torodinium robustum kofoid & swezy 4500 1 1 1 warnowia maculata (kofoid & swezy) lindemann 15 750 1 woloszynkia reticulata thompson 1700 b, n 1 1 class prymnesiophyceae corimbellus aureus green 260 mn 1 1 emiliania huxleyi (lohmann) hay & mohler 400 c 1 2 1 2 1 zigosphaera massilii (borsetti & cati) heimdal 700 1 1 1 phaeocystis pouchetii (hariot) lagerheim 35 b m 3 4 3 3 4 primnesium sp. 1 2 class cryptophyceae chroomonas marina (büttner) butcher 1100 n 1 1 1 hilea fusiformis (schiller) schiller 64 tab? n 1 2 1 2 h. marina butcher 18 tab? n 2 2 3 1 1 leucocryptos marina (braarud) butcher 480 ab mn 1 1 plagioselmis prolonga butcher 750 1 1 1 1 teleaulax acuta (butcher) hill 340 mn 1 1 1 2 class chrysophyceae calicomonas gracilis 20 2 2 2 calicomonas sp. 3 dinobryon balticum (schütt) lemmermann 800 ab m 1 2 2 3 d. belgica meunier 600 ab m 1 1 1 d. faculiferum (willén) willén 260 ab mn 1 1 1 ochromonas crenata klebs 300 b, n 1 1 1 3 3 o. marina lackey 480 ab n 1 1 class dictyochophyceae dictyocha fi bula ehrenberg 5500 tab? m 1 1 d. speculum ehrenberg 6900 c e, n 1 1 1 division chlorophyta class chlorophyceae carteria sp. 1 1 2 chlamidomonas sp. 1 2 1 tetraselmis sp. 1 class euglenophyceae 1 eutreptiella braarudii throndsen 7500 ab n 1 1 1 1 e. eupharyngea moestrup & norris 600 ab n 1 1 1 1 1 e. gymnastica throndsen 2000 n 1 1 2 1 e. hirudoidea butcher 560 n 1 eutreptia sp. 1 1 euglena acus 12000 1 1 1 class prasinophyceae halosphaera viridis schmitz 171 500 c 1 1 1 micromonas pusilla (butcher) manton & parke 4 tab? mn 2 pachysphaera marshalia parke 100 tab? m 1 1 pterosperma vanhoffenii (jørgensen) ostenfeld 32 000 mn 1 1 pyramimonas grossii parke 50 c? 2 1 1 2 2 p. orientalis mcfadden, hill & wetherbee 30 tab? n 1 2 1 resultor micron (throndsen) moestrup 4 n 1 cyanobacteria anabaenopsis sp. 1 synechococcus sp. 1 2 phylum zoomastigophora class kinetoplastida telonema subtilis griessmann 300 n 1 1 1 1 class choanofl agellidea calliacantha natans (grøntved) leadbeater 32 ab mn 2 2 2 parvicorbicula socialis ? (meunier) defl andre 20 ab n 3 4 3 2 3 monosiga marina grøntved 100 tab? m 3 3 2 2 pleurasiga reinoldsii throndsen 6900 tab? n 1 class raphidophyceae heterosigma akashiwo (hada) hada 768 tab? b, n 1 1 3 1 abundance white sea bar. sea c el l v ol . (m µ3 ) r an ge e co lo gy ic e sn ow w at er ic e w at er abundance white sea bar. sea c el l v ol . (m µ3 ) r an ge e co lo gy ic e sn ow w at er ic e w at er table continued from previous column. table continued from previous column. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice doi:10.3402/polar.v33.19235 r e s e a r c h / r e v i e w a r t i c l e plant co-existence patterns and high-arctic vegetation composition in three common plant communities in north-east greenland oriol grau,1 josep m. ninot,1 aaron pérez-haase1 & terry v. callaghan2,3 1 department of plant biology and institute for research on biodiversity, university of barcelona, av. diagonal 643, es-08028 barcelona, catalonia, spain 2 royal swedish academy of sciences, lilla frescativägen 4a, se-114 18, stockholm, sweden 3 department of animal and plant sciences, university of sheffield, s10 2tn sheffield, uk keywords abiotic stress; arctic vegetation; co-existence patterns; plant community; species richness. correspondence oriol grau, department of plant biology, university of barcelona, av. diagonal 643, es-08028 barcelona, catalonia, spain. e-mail: grau.oriol@gmail.com abstract arctic regions are expected to experience substantial changes in climate in the coming decades. in order to predict potential changes of arctic vegetation, it is important to understand the distinct role of life forms of plants and of individual species in relation to plant co-existence patterns. our aim is to investigate if three common arctic plant patch types dominated by contrasting life forms (by the dwarf shrubs salix arctica or dryas octopetala �intermedia or by mosses) are related (a) to the co-existence of vascular plants and species richness at patch scale and (b) to the floristic composition in three distinct plant communities (salix snowbed, dryas heath and fell-field) associated with contrasting abiotic regimes. the study was conducted at zackenberg, in northeast greenland. dryas patches showed a clear negative effect on smallscale plant richness and co-existence in the fell-field. salix and moss patches showed a similar pattern in all the plant communities, although the number of individuals growing in salix patches was lower than in moss patches. salix and mosses in the fell-fields hosted a high number of species in spite of the much less vegetated aspect of this harsh, upper zone. the floristic composition varied between plant communities, but it did not change substantially between patch types within each community. this study provides novel background knowledge of plant co-existence patterns at patch scale and of the structure of contrasting arctic plant communities, which will help to better assess the potential effects of varying abiotic stress regimes on arctic vegetation. to access the supplementary material for this article, please see the supplementary files under article tools online. arctic regions are expected to continue to experience substantial changes in climate in the coming decades according to most recent models and assessments (symon et al. 2005; solomon et al. 2007; amap 2011). there is growing confidence that there will be a marked increase in mean annual temperatures and changes in precipitation regimes, particularly snow (brown & mote 2009). the regional models project much larger local temperature increases in winter, compared with other seasons, particularly along greenland’s east coast. this is related to the retreat of sea ice and increased precipitation in northern greenland (stendel et al. 2008). the marked effect of climate change on organisms (e.g., post et al. 2009; callaghan, tweedie et al. 2011) and on ecosystem functioning (e.g., euskirchen et al. 2006; lara et al. 2012; myers-smith et al. 2011) in the arctic and the consequences of these effects at a larger scale have led to an increasing importance of understanding climate� ecosystem interactions in northern latitudes, particularly as not all ecosystems have responded as expected to climate change (callaghan, tweedie et al. 2011; van bogaert et al. 2011). polar research 2014. # 2014 o. grau et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 19235, http://dx.doi.org/10.3402/polar.v33.19235 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/article/view/19235 http://dx.doi.org/10.3402/polar.v33.19235 snow cover and length of the growing season are crucial factors determining the characteristics and functioning of plant communities occurring in deglaciated areas in the arctic (evans et al. 1989; elberling et al. 2008; callaghan, johansson et al. 2011). for instance, substantial phenological changes have already been detected recently in plants in response to advanced snowmelt in north-eastern greenland (høye et al. 2007; schmidt et al. 2012) and to manipulated and natural extreme thaw events in the sub-arctic in winter (bokhorst et al. 2009). variations of snow cover regimes lead to marked changes of abiotic soil parameters, such as water content, temperature or depth of the active layer; snow acts both as a resource for vegetation (e.g., moisture store) and as an abiotic stressor (e.g., constraining the length of the growing season). the dynamic balance between variations in the resource and abiotic stresses on plants is important because this balance is expected to determine the nature of plant�plant interactions (lortie et al. 2004) and thus control the plant co-existence patterns. the distinct role of contrasting life forms of plants and of individual species in relation to co-existence patterns in arctic environments remains poorly explored (pajunen et al. 2011), although this issue is crucial to understand potential changes of vegetation under varying abiotic stress regimes. dwarf shrubs are a dominant life form in cold regions and have expanded during the last decades in northern latitudes (hallinger & wilmking 2011; myers-smith et al. 2011; rundqvist et al. 2011). they have been described as potential facilitators or as drivers of plant co-existence and plant community composition in cold environments, such as in alpine, sub-arctic and arctic ecosystems (klanderud & totland 2004; graae et al. 2011; grau et al. 2012). on the other hand, in cold regions, mosses are also very abundant and expected to decrease under a warmer climate (wijk et al. 2003; walker et al. 2006) or with increasing snow cover (wahren et al. 2005); mosses have been described as crucial drivers of vascular plant recruitment and plant composition in the sub-arctic (soudzilovskaia et al. 2011). nevertheless, it remains unknown if and how shrubs or mosses affect the plant co-existence patterns at patch scale and the plant community composition under contrasting abiotic regimes in high-arctic ecosystems. our aim is to investigate if distinct common arctic plant patch types dominated by dwarf shrubs and mosses are related to the co-existence of vascular plants and species richness at patch scale and the floristic similarity in three distinct plant communities. the plant communities are salix snowbed, dryas heath and fell-field, which are associated with contrasting abiotic regimes, with regard to snow cover, soil water saturation, active layer depth or soil temperature (see table 1). the patch types selected within these three plant communities were patches with high dominance of salix arctica pall., dryas octopetala l. �intermedia vahl.*hereafter salix and dryas, respectively*and patches without any dominating dwarf table 1 attributes of the communities sampled and mean values (9standard deviation) of some relevant biotic and abiotic variables. fell-field dryas heath salix snowbed altitude (m a.s.l.)a 300�600 150�300 b150 m slope angle (8) 13 11 0 cover of main patch types (%) dryas 14.0797.38 40.2995.03 11.5999.78 salix 7.8593.42 25.1797.25 50.0998.76 mosses 6.4494.09 19.27917.57 24.17914.13 leaf dry weight per area (g/m 2 ) at patch scale dryas 92919 71919 98913 salix 83921 74910 7094 leaf n*(%) b dryas 1.4690.25 1.6290.32 1.6590.36 salix 1.9590.27 2.3890.16 2.3390.28 leaf c/n dryas 30.5794.20 26.5694.36 28.1899.23 salix 22.1592.48 18.1191.24 18.6892.11 average snow depth c no snow or irregular snow cover 61 cm 95 cm % water saturation (per vol., at 0�5 cm)c b40 40�60 65�90 soil t8c at 5 cmc,d not determined 9.193.8 7.693.8 soil parametersc increasing soil water content from fell-field to snowbed increasing soil element stocks from fell-field to snowbed decreasing active layer depth from fell-field to snowbed aaccording to bay (1998). b % n is significantly lower in the fell-field in both salix and in dryas patches, compared to the heath and to the snowbed. dryas patches also show significantly lower values of % n compared to those in salix patches. see supplementary fig. s4. cdata from elberling et al. 2008. d average of hourly readings in july and august. plant communities in north-east greenland o. grau et al. 2 (page number not for citation purpose) citation: polar research 2014, 33, 19235, http://dx.doi.org/10.3402/polar.v33.19235 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/article/view/19235 http://dx.doi.org/10.3402/polar.v33.19235 shrub but covered with a thin layer of mosses. these three patch types show obvious structural differences between them (for instance, the density of the covering canopy, litter accumulation, biomass dry weight/fresh weight; see patch type descriptions below and table 1), which may result in different plant co-existence patterns. we hypothesize that the structural differences between the distinct patch types (i.e., salix, dryas and mosses) will lead to varying species co-existence and richness patterns at patch scale independently of the community type in which they occur. material and methods study area the study was conducted in july 2011 along the southwestern slope of mount aucellabjerg, in the zackenberg valley, near the zackenberg research station (74830?n, 20830?w), on the north-eastern coast of greenland. this area was deglaciated about 10 000 years ago and currently its high-arctic climate is strongly affected by the wide and dense belt of polar pack ice on the coast, which makes the climate more continental, with very cold winters, little precipitation and sunny summers (meltofte & rasch 2008). during the polar night, monthly mean air temperatures are below �208c, with dominating northerly winds. in the snow-free summer period, the mean monthly air temperatures vary between 38c and 78c in july and august and daily temperatures rarely get below zero during this warmest part of the summer season (hansen et al. 2008). the growing season at zackenberg starts in late may in early snow-free areas, while extensive snow cover may prevail into early summer in snowdrift areas (meltofte & rasch 2008). the average annual accumulated precipitation at zackenberg was 261 mm for the years 1996�2005, of which 10% was rain and 7% was mixed precipitation. for the period 1958�2005, there has been an increase of 1.9 mm/year in the annual precipitation and a significant annual warming of 2.258c for the period 1991�2005 (hansen et al. 2008). plant communities we selected three main plant communities occurring along the altitudinal gradient (35 m to 450 m a.s.l.) in aucellabjerg. these were representative of the vegetation commonly found at low, medium and high elevation, respectively. the communities were the salix snowbed, occurring mainly at the bottom of the valley, with high vegetation cover; the dryas heath, which is found at intermediate altitudes, still with substantial plant cover; and the fell-field, dominated also by dryas but with sparse vegetation (bay 1998; table 1). these three plant communities are also associated with decreasing snow thickness from salix snowbeds in the valley bottom to the fell-fields at higher altitude; wind-blown snow accumulates on valley bottoms, where snowdrifts persist until early summer (hinkler et al. 2008). at higher altitudes the effect of wind becomes progressively stronger, and snow is frequently blown away throughout the winter season. therefore, there is intermediate snow accumulation in the dryas heath and less accumulation in the fell-fields. soil water content and storage of organic matter increases from the fell-field to the salix snowbed, whereas the active layer depth shows the opposite trend (table 1); the maximum active layer depth (as determined by the 08c isotherm; christiansen et al. 2008) is reached by the end of august. it is about 80 cm deep at the dryas heath and about 45 cm in salix snowbeds (elberling et al. 2008; meltofte & rasch 2008). patch types and study species in each plant community, we searched for three distinct patch types, each dominated (�80% cover) by (1) salix, (2) dryas or (3) mosses, as described below. salix is a dominating dwarf shrub in the zackenberg valley (bay 1998) which thrives in a wide niche range, from sand and almost barren moraine tills, to snowbeds* where it is dominant*and open fell-fields. it shows wide morphological plasticity, forming diffuse mats with long twigs and large leaves in disturbed spots or under low competitive conditions, and smaller structures in fell-fields or in denser tundra. salix comprises a larger component of musk oxen (ovibos moschatus) and collared lemming (dicrostonyx groenlandicus) diet than dryas (klein & bay 1994; berg et al. 2008). dryas is also a dominating dwarf shrub in the study area and is an arctic�alpine species, which has a circumpolar distribution in the northern hemisphere. it has also a wide niche, although it is less opportunistic and also less adapted to long lasting snow cover than salix (bay 1998). in the zackenberg region, it forms dense cushion-shaped mats which protrude from the bare soil in the fell-fields, or from flat ground or small convexities in moister tundra and snowbeds. dryas mats have this compact, dense structure as they retain a great amount of dead leaves attached to the stem. it shows higher dry weight/area (table 1) and higher dry weight/fresh weight ratios than salix (supplementary fig. s1a). dryas dominates in the heaths but also occurs sparsely in the snowbed and in the fell-fields. o. grau et al. plant communities in north-east greenland citation: polar research 2014, 33, 19235, http://dx.doi.org/10.3402/polar.v33.19235 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/article/view/19235 http://dx.doi.org/10.3402/polar.v33.19235 the third patch type is comprised of mosses without any dominant co-occurring shrub; the distinct moss species forming this patch type could not be identified, partly because of their early stage of seasonal development during the sampling period. the mosses showed a rather homogeneous structural aspect and stage of development; this patch type was dominated by poorly developed moss carpets or tiny layers of prothalli, although some small spots with cushion-shaped acrocarpic mosses (such as polytrichum sp.) and sparse macrolichens (such as cetraria ricetroum opiz, peltigera rufescens (weiss) humb. and stereocaulon gr. alpinum laurer ex funck) were present. in this patch type there was very little biomass production and litter accumulation compared to salix and dryas patches. the plants growing in the mosses were therefore not generally affected by shade from a covering canopy as occurred in the shrub patches. data collection we selected three study plots at similar altitudes within each plant community (i.e., salix snowbed, 35�43 m a.s.l.; dryas heath, 182�240 m a.s.l; and fell-field, 415�450 m a.s.l; fig. 1), separated by a few hundred metres from each other, but with similar orientation (mainly south-west). in a radius of approximately 10 m (fig. 1) within each plot, we searched for the three distinct patch types. to clearly elucidate the effects of each patch type, mixed patches were rejected. thus only those where dryas or salix or mosses clearly dominated (�80%) were considered. for instance, we avoided those dryas or salix patches which contained high cover of mosses. within each patch type we sampled four 25 �25 cm quadrats, which were treated as subsamples (n �4 subsamples �3 patch types �3 plots �3 plant communities �108 quadrats in total; see fig. 1). each quadrat was surveyed with a rigid frame divided into 100 2.5 �2.5 cm squares. the quadrats were separated by only a few metres (generally 2�8 m), and they were always put on patches which were bigger than 25 �25 cm. in each quadrat we recorded species present and estimated the number of individuals. clonal species growing in adjacent 2.5 cm squares within the frame were considered as one single individual when counting the total number of individuals, unless they could be clearly identified as separate individuals (i.e., if visibly recently germinated). however, it is acknowledged that determining an individual of a clonal plant is difficult in practice (callaghan et al. 1999). in order to describe the patch types in terms of aboveground biomass and availability of nitrogen in leaves, we sampled leaves of salix and dryas. we clipped a surface of 10 �10 cm for salix and 7 �7 cm for dryas (the latter showed a more uniform canopy and this amount was considered sufficient). the fresh leaves were kept moist in small, sealed plastic bags and promptly taken to the laboratory. there green leaves were removed and fresh weights obtained. leaves were then dried at 708c for 24 h and the dry weight measured. leaf dry matter content (dry weight/fresh weight) and the ratio of leaf dry weight to area covered were calculated (supplementary fig. s1). nitrogen and carbon concentrations were determined with an elemental analyser (ea1108, series 1; carlo erba instrumentazione, milan, italy). to evaluate the% cover of each patch type in each plant community, we recorded the occurrence of the distinct patch types every 5 cm along five parallel lines of 5 m length in each study plot (see table 1). data analyses the data were analysed using r software (r development core team 2012). to investigate whether the total number of species and individuals varied, we used a linear mixed model with poisson error structure, using the lme4 package (bates & maechler 2010). the number fig. 1 scheme of the experimental design: in each of the three plant communities*fell-field, dryas heath and salix snowbed*three plots were chosen, which were separated by a few hundred metres from each other; within a radius of ca. 10 m in each plot, three patch types were analysed: m�mosses; d�dryas; and s�salix. four 25�25 cm quadrats (subsamples) of each of these three patch types were chosen randomly within each plot. plant communities in north-east greenland o. grau et al. 4 (page number not for citation purpose) citation: polar research 2014, 33, 19235, http://dx.doi.org/10.3402/polar.v33.19235 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/article/view/19235 http://dx.doi.org/10.3402/polar.v33.19235 of species or the number of individuals was the response variable; ‘‘plant community’’ and ‘‘patch type’’ were fixed factors and ‘‘patch type’’ was nested within ‘‘plot’’ as a random factor in the model. other parameters were analysed to investigate the specific composition and structure of the patch types and plant communities studied. we used species accumulation curves to calculate the bdiversity values, which are a degree measure of uniformity of the species pool if interpreted together with the species fidelity values. to estimate species richness at the patch scale in each community, species accumulation curves were obtained by counting the number of species found when increasing the area sampled for each patch type in each community; all of the quadrats of a given patch type �plant community combination were taken as a whole and were added in a random order for 100 times to obtain the final accumulation curves with the vegan package (oksanen et al. 2009). from these curves we calculated the b-diversity (whittaker 1972), defined here as the ratio relating the final species richness in the accumulation curve (n �12 quadrats) to the mean initial richness value in the accumulation curve (n �1 quadrat). species fidelity was calculated as implemented in ginkgo (a vegetation data analyser developed by de cáceres 2012) for all species in each patch type �plant community combination. the fidelity measures the degree to which a species is confined to a given group (legendre & legendre 2003). we used the phi fidelity statistic (f) as defined by chytrý et al. (2002): / ¼ n � np � n � np ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi n � np � n � nð þ � n � npð þ p this equation takes into account the number of quadrats in the data set (n); the number of relevés in the particular vegetation unit (np); the number of occurrences of the species in the data set (n); and the number of occurrences of the species in the particular vegetation unit (np). the value 1 indicates that the species and the vegetation units are completely faithful to each other; only the more faithful (f�0.3) and the less faithful (fb�0.3) species are shown. to assess the floristic similarity between each patch type�plant community combination, we performed a principal components analysis (pca) by using the factominer package (husson et al. 2011). abundance data was transformed by the hellinger transformation (legendre & gallagher 2001) with the ginkgo multivariate data analyser (de cáceres 2012). the hellinger distance more strongly reduces the highest abundance values compared to low values and avoids the similarities derived from sharing absent species (legendre & legendre 2003; borcard et al. 2011). the results are identical to pca based on a symmetrical matrix of hellinger distances between objects. results plant species richness and co-existence patterns the total number of individual vascular plants counted was 974 in the snowbed community, 994 in the heath and only 556 in the fell-field. forty eight species were recorded. the number of individuals in salix patches was lower than in moss patches (fig. 2a; supplementary table s1). species number did not differ between the distinct patch types in snowbed and heath communities, but these numbers were significantly lower in dryas patches in the fell-field community (fig. 2b; supplementary table s1). species accumulation curves for the distinct patch type �plant community combinations (fig. 3) indicated that dryas patches generally accumulate (assuming that associations among species are directly caused by the presence of the dominant species) the lowest absolute number of species when considering all the sampled quadrats, irrespective of the plant community. in the fell-field, dryas patches promoted a clearly lower final accumulation of species with increasing sampling area compared to salix and moss patches in this community. dryas patches also showed rather lower species accumulation in the heath, but this difference became less evident in the snowbed community. species accumulation was especially high in moss patches in all plant communities. the effect of dryas on the b-diversity was highest in the fell-field and lowest in the other communities (supplementary table s2). plant communities the pca in fig. 4 shows the ecological distances (i.e., differences in species similarity based on the hellinger distance) between the distinct patch type �plant community combinations and indicates that the three plant communities studied may be clearly distinguished from each other by their flora. however, there was no clear difference between patch types if plant communities were analysed separately (results not shown), suggesting that the plots sampled within the plant communities were less variable than plots of the same patch in different communities. when analysing only presence/absence of species in a pca ordination, therefore irrespective of their local abundance (supplementary fig. s3), we observed a very o. grau et al. plant communities in north-east greenland citation: polar research 2014, 33, 19235, http://dx.doi.org/10.3402/polar.v33.19235 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/article/view/19235 http://dx.doi.org/10.3402/polar.v33.19235 similar pattern and we did not detect a clear segregation related to patch types either. species fidelity in agreement with the species ordination shown in fig. 4, the pool of species showing high or low fidelity to the distinct patch type �plant community combinations (table 2) varied more between communities than it did between patch types within each plant community. the highest fidelities were reached in moss patches in the fellfield and the lowest in this same community but in salix and dryas patches. no species showed high fidelity to dryas patches in the fell-field. when the fidelity was analysed for the whole species pool, irrespective of the patch type, several species showed high fidelity to each plant community. in the salix snowbeds the species with highest fidelity (f value higher than 0.3) were hierochloe alpina, arctagrostis latifolia, luzula confusa and alopecurus borealis; in the heath the high fidelity species were poa arctica, kobresia myosuroides and festuca brachyphylla; in the fell-field the species showing high fidelity were mostly of the genus saxifraga (s. cernua, s. integrifolia, s. nivalis, s. oppositifolia and s. platysepala) but also the grass poa glauca. discussion dominant species most likely determine the species associations at a site. in our study, dryas patches had a fig. 2 (a) number of individuals and (b) number of species found in the salix snowbed, the dryas heath and the fell-field in each patch type (moss, salix, dryas). fig. 3 species accumulation curves for all the distinct patch type� plant community combinations. fd�fell-field dryas patches, fm�moss patches; fs �salix patches; hd�dryas heath dryas patches; hm�moss patches; hs �salix patches; sd �salix snowbed dryas patches; sm �moss patches; and ss �salix patches. plant communities in north-east greenland o. grau et al. 6 (page number not for citation purpose) citation: polar research 2014, 33, 19235, http://dx.doi.org/10.3402/polar.v33.19235 http://www.polarresearch.net/index.php/polar/article/view/19235 http://dx.doi.org/10.3402/polar.v33.19235 clear negative effect on small-scale plant richness and co-existence in the fell-field. we found that the negative impact of dryas on plant co-existence can occur in high-arctic ecosystems depending on the environmental constraints, even though it has been commonly described as a facilitator low shrub in northern latitudes (chapin et al. 1994; cooper et al. 2004). klanderud & totland (2004) predicted dryas would have a negative impact on alpine, but not on high-arctic, community diversity. salix and moss patches supported a high number of species in the less vegetated upper zone. in fact, salix and mosses showed a similar pattern across all the plant communities analysed. plant co-existence and eventual establishment within the dominant vegetation are governed by many factors, including both external factors*e.g., availability of airborne seeds (klanderud & totland 2007)*and factors modulated by the species already present (pajunen et al. 2011), which may also affect microhabitat characteristics* e.g., the accumulation of allelopathic substances or the structure of the canopy of the dominant species, which has important effects on the availability of light to plants growing below (shevtsova et al. 1995; totland & esaete 2002), or on the provision of moisture, shelter and nutrients. viable seed rain would be expected to decrease with increasing altitude (thompson 1978). however, the equally high number of individuals and species observed in salix and in moss patches in the fell-field compared to the other two communities suggests that the differing pattern of plant co-existence (and expected eventual establishment) observed in dryas patches is not primarily limited by seed availability. structural differences between mosses and salix may explain the lower number of individuals occurring in salix patches; however, rather similar growth forms like the dwarf shrubs salix and dryas did not promote a similar pattern of plant co-existence. our results therefore suggest that structural differences between patch types did not clearly explain the co-existence patterns observed between patches in terms of number of individuals and species. alternative explanations should be considered instead. a possible explanation for the pattern observed in dryas compared to the other patch types, irrespective of the physical structure of the dominant species, could be that dryas lacks energy-demanding n-fixing nodulation at higher elevations, whereas at lower elevations it becomes nodulated (kohls et al. 1994). therefore, we speculate that dryas growing under the severe conditions fig. 4 principal component analysis based on the floristic similarity of the distinct patch type�plant community combinations. fd �fell-field dryas patches; fm �moss patches; fs �salix patches; hd �dryas heath dryas patches; hm �moss patches; hs�salix patches; sd�salix snowbed dryas patches; sm �moss patches; and ss�salix patches. table 2 list of species with highest (positive values) and lowest (negative values) fidelity to the distinct patch type �plant community combinations; �1 indicates no fidelity to a plant community, whereas �1 indicates maximum fidelity. only the species with values of fidelity equal to or higher than 0.3 and those with values equal to or lower than �0.3 are shown. dryas mosses salix fell-field luzula confusa �0.41 saxifraga platysepala 0.62 poa glauca 0.49 poa glauca 0.41 saxifraga cernua 0.45 sagina intermedia 0.43 sagina intermedia 0.32 festuca rubra ssp. richardsonii 0.39 luzula confusa �0.35 saxifraga nivalis 0.39 dryas heath kobresia myosuroides 0.52 poa arctica 0.41 poa arctica 0.34 festuca brachyphylla 0.43 potentilla hyparctica 0.3 carex bigelowii 0.3 salix snowbed hierochloe alpina 0.52 alopecurus borealis 0.44 hierochloe alpina 0.52 arctagrostis latifolia 0.41 salix arctica 0.34 arctagrostis latifolia 0.33 salix arctica 0.34 arctagrostis latifolia 0.33 luzula confusa 0.3 stellaria longipes s.l. 0.3 o. grau et al. plant communities in north-east greenland citation: polar research 2014, 33, 19235, http://dx.doi.org/10.3402/polar.v33.19235 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19235 http://dx.doi.org/10.3402/polar.v33.19235 found in the fell-fields may act as a stronger competitor for soil n and may thus reduce its recruiting capacity for potential neighbour competitors (tilman et al. 2001). this would contrast with the theory that predicts that species richness is higher in relatively harsh environmental conditions compared to more favourable sites due to the relatively minor role of competition in these systems (e.g., grime 1979). our study suggests that this would not apply to such very extreme conditions in the high-arctic as those found in the fell-field. on the other hand, dryas at the fell-field might actively inhibit recruitment to a higher degree than salix and mosses by producing allelopathic substances, as plants may respond to varying stress factors by changing their content of secondary plant metabolites (berg et al. 2008). in any case, further research is needed in relation to possible n-fixation and allelopathy to better understand the observed patterns of plant co-existence in these poorly studied arctic plant communities. the high b-diversity observed in dryas patches in the fell-field (supplementary table s2) seems to be related to the low fidelity of the few species occurring at the patch scale (figs. 2b, 3; supplementary table s3), which favours a high species turnover between the distinct sampled quadrats. the species found in dryas patches in the fell-field differed greatly between quadrats but generally co-occurred with polygonum viviparum, which was highly abundant in all quadrats (supplementary table s3). all the other patch type �plant community combinations showed higher species richness and higher fidelity values, but lower b-diversity, as the species pool was more uniform between quadrats and more similar to the species pool at the community scale. floristic similarity based on the hellinger distance (fig. 4) varied between plant communities, but it did not change substantially between patch types within each community. even though plant co-existence patterns and species richness varied at patch scale, the floristic similarity was determined at community scale, as indicated by the similarity between patch types within each community and by the marked differences between communities (fig. 4; supplementary fig. s3). the fell-field is the most environmentally harsh community, as low plant cover, aboveground primary production and foliar n content are all low (table 1). moss and the salix patches act as small biodiversity ‘‘hot spots’’ in this highly stressed plant community. the floristic similarity of dryas heath is intermediate between the fell-field and the snowbed (fig. 4). however, the similar species richness and co-existence patterns of dryas heath and the salix snowbed indicate that these two plant communities may be influenced by a similar overall stress regime despite the differences in the characteristics of the abiotic stress occurring in each community (table 1). these two communities have a lower overall stress balance than that found at the fell-field. our results suggest that the richness and the plant co-existence patterns vary between patch types if influenced by strong abiotic stress. it is predicted that the study area will undergo changes in precipitation and snow cover in the future (stendel et al. 2008; brown & mote 2009; amap 2011); altering the abiotic stress regimes will affect the nature of plant�plant interactions (lortie et al. 2004) and eventually the plant co-existence patterns. if these predicted changes promote stronger abiotic stress, the arctic plant communities dominated by dryas may decrease and this will show a decrease in species richness through increased negative interactions of this dwarf shrub on the co-occurring plant species. further, any changes on the stress regimes altering moss and salix cover occurring in the fell-fields may promote changes in species richness and diversity at the community scale. conclusions under a strong abiotic stress regime such as that found at the fell-field, the distinct dominant patch types (i.e., mosses, salix and dryas) did not show uniform plant species richness and co-existence patterns; in the comparatively more benign communities (i.e., salix snowbed and dryas heath) the distinct patch types showed similar patterns. we therefore predict that any future environmental changes altering the occurrence of the dominant patch types in fell-fields in the high-arctic may greatly alter plant species richness and co-existence patterns. further, the contrasting abiotic conditions in the three plant communities strongly determined the floristic composition based on ecological distances at community scale. this study provides novel insight on plant co-existence patterns and on the structure of contrasting arctic plant communities in this remote region in north-east greenland. our research will help to better assess the potential effects of varying abiotic stress regimes on arctic vegetation. acknowledgements the research leading to these results has received funding from interact (grant agreement no. 262693) under the european community’s seventh framework program, and from the research project no. 2009sgr451 from the agaur agency of the catalan government. we thank plant communities in north-east greenland o. grau et al. 8 (page number not for citation purpose) citation: polar research 2014, 33, 19235, http://dx.doi.org/10.3402/polar.v33.19235 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/19235/0 http://www.polarresearch.net/index.php/polar/article/view/19235 http://dx.doi.org/10.3402/polar.v33.19235 niels m. schmidt for his useful advices and the staff at the zackenberg research station for logistical support. we also thank two anonymous reviewers and bente j. graae for providing helpful comments on earlier versions of the manuscript. references amap (arctic monitoring and assessment programme) 2011. snow, water, ice and permafrost in the arctic (swipa). oslo: arctic monitoring and assessment programme. bates d. & maechler m. 2010. lme4: linear mixed-effects models using s4 classes. r package version 0.999375-33. accessed on the internet at http://cran.r-project.org/package�lme4 on 1 june 2010. bay c. 1998. vegetation mapping of zackenberg valley, northeast greenland. copenhagen: danish polar center and botanical museum, university of copenhagen. berg t.b., schmidt n.m., høye t.t., aastrup p.j., hendrichsen d.k., forchhammer m.c. & klein d.r. 2008. high-arctic plant�herbivore interactions under climate influence. advances in ecological research 40, 275�298. bokhorst s., bjerke j.w., tømmervik h., callaghan t.v. & phoenix g.k. 2009. winter warming events damage subarctic vegetation: consistent evidence from an experimental manipulation and a natural event. journal of ecology 97, 1408�1415. borcard d., gillet f. & legendre p. 2011. numerical ecology with r. dordrecht: springer. brown r.d. & mote p.w. 2009. the response of northern hemisphere snow cover to a changing climate. journal of climate 22, 2124�2145. callaghan t.v., johansson m., brown r.d., groisman p.y., labba n., radionov v., bradley r.s., blangy s., bulygina o.n., christensen t.r., colman j.e., essery r.l.h., forbes b.c., forchhammer m.c., golubev v.n., honrath r.e., juday g.p., meshcherskaya a.v., phoenix g.k., pomeroy j., rautio a., robinson d.a., schmidt n.m., serreze m.c., shevchenko v.p., shiklomanov a.i., shmakin a.b., sköld p., sturm m., woo m. & wood e.f. 2011. multiple effects of changes in arctic snow cover. ambio 40, 32�45. callaghan t.v., press m.c., lee j.a., robinson d. & anderson c. 1999. spatial and temporal variability in the responses of arctic terrestrial ecosystems to environmental change. polar research 18, 1�7. callaghan t.v., tweedie c.e., åkerman j., andrews c., bergstedt j., butler m.g., christensen t.r., cooley d., dahlberg u., danby r.k., daniëls f.j., de molenaar j.g., dick j., mortensen c.e., ebert-may d., emanuelsson u., eriksson h., hedenås h., henry h.r.g, hik d.s., hobbie j.e., jantze e.j., jaspers c., johansson c., johansson m., johnson d.r., johnstone j.f., jonasson c., kennedy c., kenney a.j., keuper f., koh s., krebs c.j., lantuit h., lara m.j., lin d., lougheed v.l., madsen j., matveyeva n., mcewen d.c., myers-smith i.h., narozhniy y.k., olsson h., pohjola v.a., price l.w., rigét f., rundqvist s., sandström a., tamstorf m., van bogaert r., villarreal s., webber p.j. & zemtsov v.a. 2011. multi-decadal changes in tundra environments and ecosystems: synthesis of the international polar year back to the future project. ambio 40, 705�716. chapin f.s. iii, walker l.r., fastie c.l. & sharman l.c. 1994. mechanisms of primary succession following deglaciation at glacier bay, alaska. ecological monographs 64, 149�175. christiansen h.h., sigsgaard c., humlum o., rasch m. & hansen b.u. 2008. permafrost and periglacial geomorphology at zackenberg. advances in ecological research 40, 151�174. chytrý m., lubomı́r t., jason h. & zoltán b.d. 2002. determination of diagnostic species with statistical fidelity measures. journal of vegetation science 13, 79�90. cooper e.j., alsos i.g., hagen d., smith f.m., coulson s.j. & hodkinson i.d. 2004. plant recruitment in the high arctic: seed bank and seedling emergence on svalbard. journal of vegetation science 15, 115�124. de cáceres m. 2012. ginkgo user’s manual. version 1.4. accessed on the internet at http://biodiver.bio.ub.es/veganaweb/ resources/manual-ginkgo/manual.pdf on 1 october 2012. elberling b., tamstorf m.p., michelsen a., arndal m.f., sigsgaard c, illeris l., bay c., hansen b.u., christensen t.r., hansen e.s., jakobsen b.h. & beyens l. 2008. soil and plant community-characteristics and dynamics at zackenberg. advances in ecological research 40, 223�248. euskirchen e.s., mcguire a.d., kicklighter d.w., zhuang q., clein j.s., dargaville r.j., dye d.g., kimball j.s., mcdonald k.c., melillo j.m., romanovsky v.e. & smith n.v. 2006. importance of recent shifts in soil thermal dynamics on growing season length, productivity, and carbon sequestration in terrestrial high-latitude ecosystems. global change biology 12, 731�750. evans b.m., walker d.a., benson c.s., nordstrand e.a. & petersen g.w. 1989. spatial interrelationships between terrain, snow distribution and vegetation patterns at an arctic foothills site in alaska. holarctic ecology 12, 270�278. graae b.j., ejrnæs r., lang s.i., meineri e., ibarra p.t. & bruun h.h. 2011. strong microsite control of seedling recruitment in tundra. oecologia 166, 565�576. grau o., ninot j., blanco-moreno j.m., van logtestijn r.s.p, cornelissen j.h.c. & callaghan t.v. 2012. shrub�tree interactions and environmental changes drive treeline dynamics in the subarctic. oikos 121, 1680�1690. grime j.p. 1979. plant strategies and vegetation processes. chichester, uk: john wiley & sons. hallinger m. & wilmking m. 2011. no change without a cause*why climate change remains the most plausible reason for shrub growth in scandinavia. new phytologist 189, 902�908. hansen b.u., sigsgaard c., rasmussen l., cappelen j., hinkler j., mernild s.h., petersen d., tamstorf m.p., rasch m. & hasholt b. 2008. present-day climate at zackenberg. advances in ecological research 40, 111�149. hinkler j., hansen b.u., tamstorf m.p., sigsgaard c. & petersen d. 2008. snow and snow-cover in central northeast greenland. advances in ecological research 40, 175�195. o. grau et al. plant communities in north-east greenland citation: polar research 2014, 33, 19235, http://dx.doi.org/10.3402/polar.v33.19235 9 (page number not for citation purpose) http://cran.r-project.org/package=lme4 http://cran.r-project.org/package=lme4 http://cran.r-project.org/package=lme4 http://cran.r-project.org/package=lme4 http://biodiver.bio.ub.es/veganaweb/resources/manual-ginkgo/manual.pdf http://biodiver.bio.ub.es/veganaweb/resources/manual-ginkgo/manual.pdf http://www.polarresearch.net/index.php/polar/article/view/19235 http://dx.doi.org/10.3402/polar.v33.19235 høye t.t., post e., meltofte h., schmidt n.m. & forchhammer m.c. 2007. rapid advancement of spring in the high arctic. current biology 17, 449�450. husson f., julie j & lê s. 2011. factominer. accessed on the internet at http://factominer.free.fr/ on 1 december 2011. klanderud k. & totland ø. 2004. habitat dependent nurseeffects of the dwarf shrub dryas octopetala on alpine and arctic plant community structure. ecoscience 11, 410�420. klanderud k. & totland ø. 2007. the relative role of dispersal and local interactions for alpine plant community diversity under simulated climate warming. oikos 116, 1279�1288. klein d.r. & bay c. 1994. resource partitioning by mammalian herbivores in the high arctic. oecologia 97, 439�450. kohls s.j., van kessel c., baker d.d., grigal d.f. & lawrence d.b. 1994. assessment of n2 fixation and n cycling by dryas along a chronosequence within the forelands of the athabasca glacier, canada. soil biology and biochemistry 26, 623�632. lara m.j., villarreal s., johnson d.r., hollister r.d., webber p.j. & tweedie c.e. 2012. estimated change in tundra ecosystem function near barrow, alaska between 1972 and 2010. environmental research letters 7, 015507, doi: 10.1088/1748�9326/7/1/015507. legendre p. & gallagher e.d. 2001. ecologically meaningful transformations of ordinations of species data. oecologia 129, 271�280. legendre p. & legendre l. 2003. numerical ecology. 3rd edn. amsterdam: elsevier. lortie c., brooker r.w., choler p., kikvidze z., michalet r., pugnaire f.i. & callaway r.m. 2004. rethinking plant community theory. oikos 107, 433�438. meltofte h. & rasch m. 2008. the study area at zackenberg. advances in ecological research 40, 101�110. myers-smith i., forbes b., wilmking m., hallinger m., lantz t., blok d., tape k., macias-fauria m., sass-klaassen u., lévesque e., boudreau s., ropars p., hermanutz l., trant a., siegwart collier l., weijers s., rozema j., martin schmidt n., schaepman-strub g., wipf s., rixen c., ménard c., venn s., goetz s., andreu-hayles l., elmendorf s., ravolainen v., welker j., grogan pz., epstein h. & hik d. 2011. shrub expansion in tundra ecosystems: dynamics, impacts and research priorities. environmental research letter 6, 045509, doi: 10.1088/1748-9326/6/4/045509. oksanen j., kindt r., legendre p., o’hara p., simpson g.l., solymos p., steven m.h.h. & wagner h. 2009. vegan: community ecology package. r package, version 1, 15�3. accessed on the internet at http://cran.r-project.org/web/ packages/vegan/index.html on 1 june 2010. pajunen a.m., oksanen j. & virtanen r. 2011. impact of shrub canopies on understory vegetation in western eurasian tundra. journal of vegetation 22, 837�846. post e., forchhammer m.c., bret-harte s., callaghan t.v., christensen t.r., elberling b., fox a.d., gilg o., hik d.s., ims r.a., jeppesen e., klein d.r., madsen j., mcguire a.d., rysgaard s., schindler d.e., stirling i., tamstorf m.p., tyler n.j.c., van der wal r., welker j., wookey p.a., schmidt n.m. & aastrup p. 2009. ecological dynamics across the arctic associated with recent climate change. science 325, 1355�1358. r development core team 2012. r: a language and environment for statistical computing. vienna: r foundation for statistical computing. rundqvist s., hedenas h., sandstrom a., emanuelsson u., eriksson h., jonasson c. & callaghan t.v. 2011. tree and shrub expansion over the past 34 years at the tree-line near abisko, sweden. ambio 40, 683�692. schmidt n.m., kristensen d.k., michelsen a. & bay c. 2012. high arctic plant community responses to a decade of ambient warming. biodiversity 13, 191�199. shevtsova a., ojala a., neuvonen s., vieno m. & haukioja e. 1995. growth and reproduction of dwarf shrubs in a subarctic plant community: annual variation and aboveground interactions with neighbours. journal of ecology 83, 263�275. solomon s., qin d., manning m., chen z., marquis m., averyt k.b., tignor m. & miller h.l. jr. (eds.) 2007. climate change 2007. the physical science basis: contribution of working group i to the fourth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. soudzilovskaia n.a., graae b.j., douma j.c., grau o., milbau a., shevtsova a., wolters l. & cornelissen j.h.c. 2011. how do bryophytes govern generative recruitment of vascular plants? new phytologist 190, 1019�1031. stendel m., christensen j.h. & petersen d. 2008. arctic climate and climate change with a focus on greenland. advances in ecological research 40, 13�43. symon c., arris l. & heal b. (eds.) 2005. arctic climate impact assessment. cambridge: cambridge university press. thompson k. 1978. the occurrence of buried viable seeds in relation to environmental gradients. journal of biogeography 5, 425�430. tilman d., reich p.b., knops j., wedin d., mielke t. & lehman c. 2001. diversity and productivity in a long-term grassland experiment. science 294, 843�845. totland ø. & esaete j. 2002. effects of willow canopies on plant species performance in a low-alpine community. plant ecology 161, 157�166. van bogaert r., haneca k., hoogesteger j., jonasson c., de dapper m. & callaghan t.v. 2011. a century of tree line changes in sub-arctic sweden show local and regional variability and only a minor role of 20th century climate warming. journal of biogeography 38, 907�921. van wijk m., clemmensen k.e., shaver g.r., williams m., callaghan t.v., chapin f.s. iii, cornelissen j.h.c., gough l., hobbie s.e., jonasson s., lee j.a., michelsen a., press m.c., richardson s.j. & rueth h. 2003. long-term ecosystem level experiments at toolik lake, alaska, and at abisko, northern sweden: generalisations and differences in ecosystem and plant type responses to global change. global change biology 10, 105�123. wahren c.h.a., walker m.d. & bret-harte m.s. 2005. vegetation responses in alaskan arctic tundra after 8 years plant communities in north-east greenland o. grau et al. 10 (page number not for citation purpose) citation: polar research 2014, 33, 19235, http://dx.doi.org/10.3402/polar.v33.19235 http://factominer.free.fr/ http://cran.r-project.org/web/packages/vegan/index.html http://cran.r-project.org/web/packages/vegan/index.html http://www.polarresearch.net/index.php/polar/article/view/19235 http://dx.doi.org/10.3402/polar.v33.19235 of a summer warming and winter snow manipulation experiment. global change biology 11, 537�552. walker m.d., wahren c.h., hollister r.d., henry g.h.r, ahlquist l.e., alatalo j.m., bret-harte m.s., calef m.p., callaghan t.v., carroll a.b., epstein h.e., jónsdóttir i.s., klein j.a., magnússon b., molau u., oberbauer s.f., rewa s.p., robinson c.h., shaver g.r., suding k.n., thompson c.c., tolvanen a., totlandt ø., turner p.l., tweedie c.e., webber p.j. & wookey p.a. 2006. plant community responses to experimental warming across the tundra biome. proceedings of the national academy of sciences of the united states of america 103, 1342�1346. whittaker r.h. 1972. evolution and measurement of species diversity. taxon 21, 213�251. o. grau et al. plant communities in north-east greenland citation: polar research 2014, 33, 19235, http://dx.doi.org/10.3402/polar.v33.19235 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19235 http://dx.doi.org/10.3402/polar.v33.19235 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice por_016.fm 160 polar research 26 2007 160 – 167 © 2007 the authors blackwell publishing incmalden, usaporpolar research0800-03952007 blackwell publishing ltd? 2007262160167original article the salinity: δ 18 o water relationship in kongsfjorden, western spitsbergens. e. maclachlan et al. the salinity: d 18 o water relationship in kongsfjorden, western spitsbergen suzanne e. maclachlan, 1 finlo r cottier, 1 william e. n. austin 2 & john a. howe 1 1 scottish association for marine science, dunstaffnage marine laboratory, argyll, oban, pa37 1qa, uk 2 school of geography and geosciences, university of st andrews, fife, ky16 9al, uk abstract we present the first oxygen isotope measurements from kongsfjorden in north-west spitsbergen, and use the isotopic composition and hydrographic data to provide a detailed assessment of the mixing between freshwater and oceanic waters. temperature, salinity(s) and oxygen isotope profiles are used to describe the seasonal evolution of hydrography in the inner part of the fjord, and to infer the dominant mixing and exchange processes. data from atmospheric, glacial and marine sources throughout kongsfjorden are used to construct a salinity: δ 18 o mixing line in a region that receives inputs of freshwater and marine atlantic water. the dominant source of freshwater is glacial melt from a tidewater glacier complex at the head of the fjord, resulting in a seawater salinity: δ 18 o relationship where δ 18 o = 0.43s − 14.65. the kongsfjorden data provides a northern latitudinal limit for mixing lines in the northwestern european coastal system. keywords oxygen isotopes; mixing line; arctic; fjord; glacial; hydrography. the marine environment of western svalbard is strongly influenced by the west spitsbergen current (wsc), the northern extension of the norwegian atlantic current. the wsc follows the slope to the west of svalbard delivering relatively warm and saline atlantic water (aw) northwards, and is the main transport of heat to the arctic (schauer et al. 2004). colder and less saline water of arctic origin flows along the west spitsbergen shelf (wss), where an oceanic front develops with the wsc (saloranta & svendsen 2001). consequently, the wss is a location characterized by considerable exchange and mixing of atlantic and arctic waters and fjordic freshwater. glaciated arctic fjords are typically characterized by linear environmental gradients. tidewater glaciers at the head of these fjords discharge freshwater and suspended sediment into the inner parts of the fjord, whereas predominantly marine conditions prevail at the fjord mouth (cf. freeland et al. 1980 in syvitski et al. 1984). wind, tidal and geostrophic forces in such fjords can generate complex layering and mixing between water masses (svendsen et al. 2002). a recent study of kongsfjorden, spitsbergen, by cottier et al. (2005) described the intense seasonality, characterized by a fundamental shift in hydrographic conditions. a somewhat homogeneous water mass is created in winter through the processes of convection and sea-ice formation. in summer, frontal instabilities at the shelf break result in the intrusion of aw into the fjord. the volume of such intrusions varies interannually, and the controlling parameters include the magnitude and direction of shelf winds during spring and summer, and the relative density structure between the shelf and fjord waters. the application of oxygen isotope measurements for differentiating between meteoric and sea-ice meltwater has been thoroughly demonstrated (craig & gordon 1965; bedard et al. 1981; bauch et al. 1995). the latitudinal variation in the value of δ 18 o for meteoric water, caused by temperature and distance from the evaporation site, makes δ 18 o an ideal tracer to identify high-latitude freshwater sources. finally, salinity: δ 18 o mixing lines are particularly valuable in high-latitude locations, as they can be used to trace and identify the mechanism associated with deep water formation (bauch et al. 2005). the oxygen isotope ratios in fossil carbonate buried in marine sediments are considered to reflect the ratios prevailing in the ocean at the time of burial. the stable oxygen isotope ratio within calcareous organisms (such as foraminifera, molluscs, ostracods etc.) is a function of (i) the isotopic composition of the sea water, and (ii) the temperature of the water (e.g. jansen 1989). in correspondence suzanne maclachlan, geology and geophysics, national oceanography centre, university of southampton, european way, southampton, so14 3zh, uk. e-mail sucl@noc.soton.ac.uk. doi:10.1111/j.1751-8369.2007.00016.x s. e. maclachlan et al. the salinity: δ 18 o water relationship in kongsfjorden, western spitsbergen polar research 26 2007 160 – 167 © 2007 the authors 161 particular, species that calcify their shells in isotopic equilibrium with the ambient water, or where the isotopic vital effect is known, are the most useful as palaeoceanographic indicators. a comprehensive understanding of the salinity and δ 18 o properties of the encompassing water masses is therefore essential in quantifying the temperature and salinity effects encoded within the stable oxygen isotope record of calcareous organisms. a study by azetsu-scott & tan (1997) investigated the dynamics of a surface glacial meltwater plume in kangerdlugssuaq fjord, east greenland, using oxygen isotopes as a tracer. a linear relationship between salinity and δ 18 o confirmed the dominant source of freshwater in the fjord to be of glacial origin. oxygen isotope mixing lines have also been constructed for sognefjorden, western norway (mikalsen & sejrup 2000), showing a large gradient in the oxygen isotope composition from the fjord head ( − 14.5‰), increasing westward to the fjord mouth ( − 9.2‰), with a mixing line of 0.31‰ per unit salinity change. previous oceanographic investigations in kongsfjorden by svendsen et al. (2002) and cottier et al. (2005), were focused on the modification and exchange of the water masses in the outer fjord and on the adjacent shelf. for a more complete understanding of the water mass distribution within this and similar fjords, it is also important to consider the interactions between atmosphere, ocean, glacial ice and sea ice. stable isotopes can be employed to distinguish the influence of these processes on modifying the different water masses within glaciated fjords. this study investigates how mixing between oceanic, coastal and catchment waters influence the oxygen isotope composition in an arctic fjord. furthermore, the study provides data that can be utilized as a calibration tool for regional palaeoceanographic research in fjordic environments. regional setting the kongsfjorden–krossfjorden system is situated between 78 ° 04 ′ n and 79 ° 03 ′ n, and 11 ° 03 ′ e and 13 ° 3 ′ e (fig. 1). kongsfjorden is orientated south-east to north-west, is approximately 20 km long and varies from 4 to 10 km wide, and has a complex bottom topography fig. 1 location and station map of kongsfjorden. we define the outer fjord as the area north-west of ny–ålesund. + , july 2002 (cruise jr75); filled circles indicate sites used in september 2005 (cruise jr127); open diamonds indicate sites used between 30 march and 3 april 2005 (ice stations). 162 polar research 26 2007 160 – 167 © 2007 the authors the salinity: δ 18 o water relationship in kongsfjorden, western spitsbergen s. e. maclachlan et al. comprising of a number of sills and basins (howe et al. 2004). throughout the paper we subdivide the fjord into the inner fjord (south-east of ny-ålesund) and the outer fjord (north-west of ny-ålesund). the fjord has a distinct deep-water connection (at a depth of approximately 350 m) to the adjacent shelf. the dynamic character of the fjord-shelf region (saloranta & svendsen 2001) permits seasonal inflow of shelf and oceanic water masses, which impact on the hydrographic (cottier et al. 2005) and biological characteristics of the fjord (willis et al. 2006). circulation in kongsfjorden is dominated by cyclonic currents resulting from the reduced rossby radius by virtue of the high-latitude location (ingvaldsen et al. 2001). the magnitude of transverse salinity gradients in the fjords is not static but undergoes constant adjustment by the prevalence and strength of the axial fjord winds. fast ice begins to form in the inner fjord during december/january, reaching a total thickness of up to 1 m, and can break up to form drift ice in the outer fjord. loss of sea ice from the fjord is primarily the result of break-up by waves and down-fjord winds, rather than by local melting (svendsen et al. 2002). there is an active tidal glacier complex at the head of the fjord that generates steep environmental gradients in salinity, temperature, sedimentation rates and bottom sediment composition (svendsen et al. 2002). the catchment area has been estimated as 1260 km 2 , and approximately 80% of it was reported to be glaciated (ito & kudho 1997). kongsvegen and kronebreen are tidewater glaciers at the head of kongsfjorden, and together drain an area of 1013 km 2 within the holtedahlfonna ice field (bennett et al. 1999). methods the data presented come from three sampling periods: (i) july 2002 (cruise jr75) (ii) september 2005 (cruise jr127), both onboard rrs james clark ross , and (iii) 30 march–3 april 2005, sampling from stations on the fast ice (see fig. 1). temperature ( t ) and salinity ( s ) profiles in the outer fjord were recorded with a ship-deployed sea-bird electronics 911 plus conductivity-temperaturedepth (sbe9/11 + ctd) system, from which the potential temperature ( θ ) was derived. water for isotopic measurement and salinity calibration were collected using the rosette sampler on cruise jr75 (july 2002). the inner fjord was sampled during cruise jr127 using small boats. profiles of t and s were recorded at 16 stations with a hand-deployed sbe19 ctd; water column samples were collected using nio water bottles and 16 samples of ‘calved’ glacier ice were collected from the surface. winter profiles in the inner fjord were collected at four stations using a seabird sbe19 + ctd deployed through the sea ice. a guildline autosal 8400b salinometer (accuracy, ± 0.002) was used to calibrate ctd salinity data, and to determine the salinity of water samples and melted glacial ice. to minimize isotopic contamination of the glacial ice samples, a surface layer of ice was chipped away prior to storage (at − 1 ° c). further precautions before melting and analysis included removing a further surface layer of ice and transferring the sample to air-tight ‘triple-layered’ plastic bags to prevent leakage and exchange with the atmospheric oxygen. the seawater and melted ice samples for δ 18 o were transferred to 200-ml glass bottles and double sealed with a pvc stopper and a screw cap. oxygen isotope ratios were measured on a finnegan delta plus xp gas source mass spectrometer, coupled to a gasbench ii preparation system, at the school of geography and geosciences, university of st andrews. the δ 18 o measurements are based on 1-ml volumes, determined via co 2 equilibration. the mean precision of the triplicate analysis was ± 0.04‰ relative to vienna standard mean ocean water (vsmow). four samples were measured in triplicate and two internal standard waters (calibrated to vsmow) were analysed every ten samples. results figures 2a and b show the potential temperature and salinity sections for the inner fjord derived from individual ctd profiles in september 2005. the temperature section shows a cool surface layer of around 1.5 ° c or less, with a gradual increase in temperature with distance from the glacier. there is a sharp thermocline at about 5 m, with temperature increasing to a maximum of nearly 3 ° c at approximately 10 m and then gradual cooling with depth. stations ik1 and ik2 show a greater rate of cooling below 60 m depth. the salinity section does not show a clear meltwater plume with associated large longitudinal salinity gradients within the inner fjord. rather, isohalines in the surface layer at depths shallower than the sill (0–10 m) at ik9 maintain a relatively constant depth with a relatively weak longitudinal salinity gradient of 0.02 km − 1 . at the stations closest to the glacier front (ik2–ik8) there is a relatively weak vertical salinity gradient of 0.025 m − 1 at depths below the level of the sill at ik9, between isohalines 33 and 34. in contrast seaward of the sill at ik9 the corresponding vertical gradient is, salinity 0.1 m − 1 , four times greater than the gradient closer to the glacier. the 34 isohaline lies at a depth of approximately 50 m between stations ik2 and ik4, compared with a depth of 20 m between ik11 and ik16. figure 3 is a potential temperature versus salinity ( θ – s ) diagram comparing ctd data from april 2005 with data s. e. maclachlan et al. the salinity: δ 18 o water relationship in kongsfjorden, western spitsbergen polar research 26 2007 160 – 167 © 2007 the authors 163 from september 2005. a description of each water mass domain identified in fig. 3 is given by svendsen et al. (2002). in april the water in the inner fjord was rather homogeneous in temperature and salinity, which is consistent with the characteristics of winter cooled water (wcw), formed through sea-ice formation and convection, and described previously by cottier et al. (2005). this affirms previous speculation that the entire body of water in kongsfjorden becomes relatively homogeneous during the winter. the large scatter in the september 2005 data in fig. 3 is confined to the upper 12–15 m, with the θ – s relationship becoming rather well defined at salinities greater than 33. towards the glacier front the water becomes uniformly cooler and more saline with depth, indicative of diffusive vertical mixing, with a trend towards a θ – s signature typical of wcw, which may persist in the deep water from the preceding winter. seaward of the sill at ik9 the salinity also increases with depth, and remains rather warm. at 50 m the water is relatively uniform in character with θ ≅ 2 ° c and s ≅ 34.5, a salinity value that exceeds those measured in april 2005. the september 2005 δ 18 o data (table 1) show that the surface waters in the inner fjord are isotopically lighter than the deeper waters, with surface values ranging from − 1.00‰ to − 1.47‰, contrasting with a range from − 0.02‰ to 0.21‰ for deep waters. similarly to the weak surface salinity gradient (fig. 2b), there is a weak horizontal gradient in surface δ 18 o that increases seaward at 0.012‰ km − 1 . δ 18 o values increase quickly with depth such that the δ 18 o mean at a depth of approximately 35 m adjacent to the glacier front is 0.05‰. the outer fjord data generally shows higher δ 18 o values, varying from 0.06‰ to 0.51‰, corresponding to the higher salinities (see table 1). glacial ice was collected from ik2 to ik16 in the inner fjord. the δ 18 o values of these samples ranged from − 14.62‰ to − 17.96‰, with a mean of − 15.85‰. the 3.34‰ isotopic variation in the ice samples analysed is comparable with that published for svalbard ice-core data fig. 2 sections of (a) potential temperature and (b) salinity in the inner fjord. bathymetry is estimated from ctd drops and charts. station locations are indicated by the vertical dashed lines. ‘a’ indicates the approximate placement of the april stations along the transect line. isotherms are plotted at 1.0, 1.5, 2.0, 2.5 and 2.75 ° c and isohalines at 0.5 intervals between 31 and 34.5. table 1 details of δ 18 o‰ (relative to vienna standard mean ocean water, vsmow) and salinity data obtained for kongsfjorden. precipitation a inner fjord (jr127) outer fjord (jr75) 1990–2002 glacial ice surface water (0–2 m) deep water ( > 2 m) transformed aw b (6–52 m) aw b (76–354 m) range of δ 18 o from − 5.23 to − 26.58 from − 14.62 to − 17.96 from − 1.00 to − 1.47 from − 0.02 to 0.21 from 0.06 to 0.40 from 0.13 to 0.51 mean of δ 18 o − 11.55 − 15.85 − 1.22 0.10 0.20 0.24 salinity range 0 0 from 30.23 to 31.60 from 33.53 to 34.23 from 34.02 to 34.59 from 34.66 to 35.14 mean salinity 0 0 30.95 33.97 34.43 34.86 no. of samples 152 16 12 4 7 13 a precipitation values extracted from iaea (2006). b atlantic water. 164 polar research 26 2007 160 – 167 © 2007 the authors the salinity: δ 18 o water relationship in kongsfjorden, western spitsbergen s. e. maclachlan et al. (e.g. isaksson et al. 2003). such variation can be attributed to (i) variations in the age and hence δ 18 o of the ice, (ii) varying altitude at which the ice was formed, and (iii) the ice originating from any one of the five tide water glaciers that discharge into the fjord. the stable oxygen isotope composition of meteoric precipitation is primarily dependent upon the ambient local temperature. as local temperature varies with season, we have obtained monthly precipitation data from nyålesund (iaea 2006) for 1990–2002 (table 1). during this period, values for δ 18 o of precipitation varied from − 5.23‰ (october 2002) to − 22.93‰ (february 1995) with a mean of − 11.55‰. it is worth noting that a significant component of winter precipitation (october–march) within the catchment has the potential to influence the fjord δ 18 o as snowmelt. discussion figures 2 and 3 illustrate the complex hydrography and the possible modification processes occurring in the inner fjord. the occurrence of predominantly wcw in the april ctd data shown in fig. 3 is a strong indicator that input of meltwater was minimal at that time. by september, two major modifications to the salinity distribution have taken place. first, a fresh surface layer developed, through summer melt and run-off. second, there was apparent uplift of the 34 isohaline to a depth of 20 m seaward of the sill at ik9 in the inner fjord, which was probably caused by a subsurface intrusion of a more saline water mass. the primary source of saline water in this system is aw originating in the wsc. the occurrence of heavily modified aw, through mixing, in kongsfjorden has been described by svendsen et al. (2002) and was termed transformed atlantic water (taw). figure 3 confirms that there is a greater influence of aw on the seaward side of the sill at ik9, with the deep water tending towards the taw domain. however, the inflection in the θ–s distribution towards taw implies that aw is not restricted to the seaward side, but is also present closer to the glacier, although heavily mixed with the surface fig. 3 a potential temperature (θ)–salinity (s) diagram of ctd data collected in the inner fjord area in april 2005 (grey lines) and september 2005 (circles). data from stations between ik2 and ik8 are denoted by filled circles and data from stations seaward from the sill at ik9 are denoted by open circles. water mass boundaries are taken from cottier et al. (2005). external water masses are atlantic water (aw) and arctic water (arw); internal water masses are winter cooled water (wcw) and surface water (sw); water masses of mixed origin are transformed atlantic water (taw) and intermediate water (iw). s. e. maclachlan et al. the salinity: δ18o water relationship in kongsfjorden, western spitsbergen polar research 26 2007 160 – 167 © 2007 the authors 165 water and the wcw. the cool surface layer and temperature maximum at 10 m (fig. 2a) can be interpreted as previous warming of the surface through insolation, followed by a recent cooling by cold down-fjord winds. the summer salinity structure close to a glacier is often characterized by a freshwater plume (domack & ishman 1993). from the vertical and horizontal salinity gradients in fig. 2 there was no discernible subsurface plume in kongsfjorden in september 2005. furthermore, the observed contrast between δ18o values at the surface and those at depth (fig. 4a) reinforces the assertion that meltwater is restricted to the upper 15 m. the absence of a subsurface plume may be accounted for by the following: (i) the first station was approximately 2 km from the glacier front, and a buoyant plume ascending the face of the glacier could mix with ambient water with only a fresher surface layer detectable at the first station; also (ii) the cyclonic circulation in kongsfjorden (ingvaldsen et al. 2001) will tend to cause freshwater to flow to the northern side of the fjord rather than form a uniform axial plume. however, the sampling line is to the north of kongsvegen and therefore is likely to intersect a northward flowing subsurface plume. a similar absence of a subsurface plume has also been reported in an east greenland fjord (azetsu-scott & tan 1997). the salinity and isotope data for inner fjord seawater, collected in september 2005, are presented in fig. 4a as a salinity: δ18owater mixing line. it spans both the fresh surface water and those deeper waters with a stronger atlantic influence. the mixing line has a gradient of 0.42‰ per salinity unit with an intercept value at s = 0 of −14.35‰. we are also able to make an independent estimate of the zero salinity value using published data of monthly freshwater discharge into kongsfjorden from glacial and precipitation sources. svendsen et al. (2002: table 3) estimate that the total glacial source including icebergs is 1016 × 106 m3, and from precipitation is 377 × 106 m3, a volume ratio of 2.7 : 1. using δ18o values of −15.85‰ for glacial ice and −11.55‰ for precipitation (table 1), and by combining them at the appropriate volume ratio we derive a freshwater end member of −14.69‰. within the errors associated with the discharge data this is remarkably close to the intercept obtained in fig. 4a (i.e. −14.35‰) and offers a level of confirmation of the svendsen et al. (2002) data. we will use −14.69‰ as our freshwater end member. we can extend the mixing line of fig. 4b to include data from two central and outer stations, which are more influenced by aw (cottier et al. 2005), and force it through the derived freshwater end member. the calculated mixing line presented in fig. 4b shows that the data can be fitted to a line with equation δ18o = 0.43s − 14.69. this robust mixing line can be used for all areas of the fjord because of the strong linear relationship that connects the variety of mixed water masses encountered. furthermore, none of the data points deviate significantly from the mixing line towards higher or lower salinities at constant δ18o values, indicating that neither sea-ice formation (with associated brine release) nor sea-ice melt, respectively, make a significant contribution to the surface salinity (bedard et al. 1981) in kongsfjorden. a similar investigation was undertaken by azetsu-scott & tan (1997) in kangerlugssuaq fjord, eastern greenland. a salinity: δ18o relationship of δ18o = 0.69s − 24.18 fig. 4 (a) salinity: δ18o mixing line, inner fjord, september 2005 (n = 16). δ18owater = 0.42s − 14.35 (r2 = 0.977). data points are denoted by open diamonds for surface water, open circles for intermediate depth samples and open triangles for bottom water samples. (b) salinity: δ18o mixing line, kongsfjorden, july 2002 and september 2005 (n = 53). δ18owater = 0.43s − 14.69 (r2 = 0.982). data points are denoted by open diamonds for inner fjord samples, an open circle for mean meteoric value open triangles for glacial ice samples and crosses for outer fjord samples. 166 polar research 26 2007 160 – 167 © 2007 the authors the salinity: δ18o water relationship in kongsfjorden, western spitsbergen s. e. maclachlan et al. was calculated for the inner fjord. the slope of the kangerlugssuaq mixing line (0.69) is much greater than that for the inner kongsfjorden mixing line (0.43) because of the isotopic differences in the glacier ice at the head of the fjords. for instance, the glacial ice sampled from kangerlugssuaq fjord yielded an isotopic mean of −26.5‰, in comparison with −15.85‰ for kongsfjorden. the kongsfjorden data provide a northern latitudinal limit for mixing lines in the north-western european coastal system. to set our results in the context of other fjordic locations that have a strong freshwater input and an aw influence, we compare our mixing line with those derived for loch sunart, scotland (57° n) (austin & inall 2002) and sognefjorden, norway (61° n) (mikalsen & sejrup 2000) in fig. 5. the three sites lie on a latitudinal gradient, along which there is a supply of aw and a marked variation in the freshwater oxygen isotope signal. as anticipated, the slope of the mixing line in fig. 4b (0.43) is greater than relationships defined for sognefjorden, western norway (0.31) and loch sunart, western scotland (0.18). this spatial gradient in the salinity: δ18o mixing lines occurs as a result of the latitudinal effect of δ18o in precipitation (see austin and inall 2002). variations in both salinity and temperature have the potential to be imprinted in the palaeoclimate record of marine organisms. consequently, it is crucial to identify the factors (both spatial and temporal) governing δ18o within the fjordic environment. the relationship between salinity and δ18o illustrated in fig. 5 will be a valuable tool in palaeoceanographic research, particularly with respect to palaeotemperature reconstructions from arctic fjords. conclusions the combined hydrographic and isotopic data presented yield the first salinity: δ18o mixing line for the fjordic and coastal waters of western svalbard, a key high-latitude oceanographic province strongly influenced by both glacial melt and aw. we also provide the first reports of seasonal evolution of the inner fjord hydrography, showing that the influence of aw extends throughout the fjord. we demonstrate that despite the hydrographic complexity of kongsfjorden, a robust salinity: δ18o relationship exists, confirming the utility of oxygen isotopes as a tool for studying the complex relationship between water masses in an arctic environment. the resulting salinity: δ18o relationship confirms that the freshwater input to the fjord is dominated by glacial melt from the holtedahlfonna ice field, rather than by seasonal precipitation or sea-ice melt. the derived salinity: δ18o relationship provides a new palaeoceanographic proxy calibration for the region. the mixing line for kongsfjorden is a northern extreme for the fjordic north-western european coastal system. we regard the mixing line as a valid palaeoclimate tool for western svalbard fjords, and recommend its application in future palaeoclimate studies from the region, particularly those concerned with the present (holocene) interglacial period. acknowledgements we thank the officers and crew of rss james clark ross during the 2002 and 2005 cruises; also edmond hansen (norwegian polar institute) for supplying the april 2005 ctd data. colin griffiths and paul provost (scottish association for marine science) are thanked for their help with ctd operations, sample collection and salinity measurements. jonathan wynn (school of geography and geosciences, university of st andrews) is thanked for his help with stable isotope measurements. references austin w.e.n. & inall m.e. 2002. deep-water renewal in a scottish fjord: temperature, salinity and oxygen isotopes. polar research 21, 251–257. azetsu-scott k. & tan f.c. 1997. oxygen isotope studies from iceland to an east greenland fjord: behaviour of glacial meltwater plume. marine chemistry 56, 239–251. bauch d., erlenkeuser h. & andersen n. 2005: water mass processes on arctic shelves as revealed from delta o-18 of h2o. global and planetary change 48, 165–174. bauch d., schlosser p. & fairbanks r.g. 1995. freshwater balance and the sources of deep and bottom waters in the fig. 5 salinity: δ18o mixing lines: 57°n loch sunart, western scotland, δ18owater = 0.18s − 6.0 (austin & inall, 2002); 61°n sognefjorden, western norway, δ18owater = 0.37s − 12.51 (mikalsen & sejrup 2000); and 79°n kongsfjorden, western svalbard, δ18owater = 0.43s − 14.65. s. e. maclachlan et al. the salinity: δ18o water relationship in kongsfjorden, western spitsbergen polar research 26 2007 160 – 167 © 2007 the authors 167 arctic ocean inferred from the distribution of h2 18o. progress of oceanography 35, 53–80. bedard p., hillaire-marcel c. & page c. 1981. 18o modelling of freshwater inputs in baffin bay and canadian arctic coastal waters. nature 293, 287–289. bennett m.r., hambrey m.j., huddart d., glasser n.f. & crawford k. 1999. the landform and sediment assemblage produced by a tidewater glacier surge in kongsfjorden, svalbard. quaternary science reviews 18, 1213–1246. cottier f., tverberg v., inall m. e., svendsen h., nilsen f. & griffiths c. 2005. water mass modification in an arctic fjord through cross-shelf exchange: the seasonal hydrography of kongsfjorden, svalbard. journal of geophysical research, oceans 110, 1–18. craig h. & gordon l. 1965. deuterium and oxygen-18 variations in the ocean and the marine atmosphere. in e. tongiori (ed.): stable isotopes on oceanographic studies and paleotemperatures. pp. 9–130. pisa: national research council. domack e.w. & ishman s. 1993. oceanographic and physiographic controls on modern sedimentation within antarctic fjords. geological society of america bulletin 105, 1175–1189. freeland h.j., farmer d.m. & levings c.d. (eds.) 1980. fjord oceanography. nato conference series, 715. new york/london: plenum press. howe j. a., moreton s. g., morri c. & morris p. 2004. multibeam bathymetry and the depositional environments of kongsfjorden and krossfjorden, western spitsbergen, svalbard. polar research 22, 301–316. iaea (international atomic energy agency) 2006. the global network of isotopes in precipitation (gnip) and isotope hydrology information system (isohis) database. vienna: iaea. ingvaldsen r., bø-reitan m., svendsen h. & asplin l. 2001. the upper layer circulation in the kongsfjorden and krossfjorden—a complex fjord system on the west coast of spitsbergen. watanabe o. & yamanouchi t. (eds.) enviromental research in the arctic 2000: proceedings of the second international symposium on environmental research in the arctic and fifth nyålesund scientific seminar. memoirs of national institute of polar research special issue 54, 393–407. tokyo: national institute of polar research. isaksson e., hermanson m., hicks s., igarashi m., kamiyama k., moore j., motoyama h., muir d., pohjola v., vaikmae r., van der wal r. s. w. & watanabe o. 2003. ice cores from svalbard—useful archives of past climate and pollution history. physics and chemistry of the earth 28, 1217–1228. ito h. & kudho s. 1997. characteristics of water in kongsfjorden, svalbard. proceedings of the nipr symposium, polar meterology glaciology 11, 211–232. tokyo: national institute of polar research. jansen e. 1989. the use of stable oxygen isotope and carbon isotope stratigraphy as a dating tool. quaternary international 1, 151–166. mikalsen g. & sejrup h.p. 2000. oxygen isotope composition of fjord and river water in the sognefjorden drainage area, western norway. implications for paleoclimate studies. estuarine and coastal marine science 50, 441–448. saloranta t.m. & svendsen h. 2001. across the arctic front west of spitsbergen: high-resolution ctd sections from 1998–2000. polar research 20, 177–184. schauer u., fahrbach e., østerhus s. & rohardt g. 2004. arctic warming through the fram strait: oceanic heat transport from 3 years of measurements. journal of geophysical research 109, article number c06026. doi:10.1029/ 2003jc001823. svendsen h., beszczynska-møller a., hagen j. o., lefauconnier b. tverberg v., gerland s., ørbæk j. b., bischof k., papucci c., zajaczkkowski m., wiencke c., winther j.-g. & dallmann w. 2002. the physical environment of kongsfjorden–krossfjorden, an arctic fjord system in svalbard. polar research 21, 133–166. syvitski j.p., burell d.c. & skei j. (eds.) 1984. fjords: processes and products. new york: springer verlag. willis k., cottier f., kwasniewski s., wold a. & falk-petersen s. 2006. the influence of advection on zooplankton community composition in an arctic fjord (kongsfjorden, svalbard). journal of marine systems 61, 39–54. doi:10.3402/polar.v35.28765 r e s e a r c h / r e v i e w a r t i c l e first records of aphid-pathogenic entomophthorales in the sub-antarctic archipelagos of crozet and kerguelen bernard papierok,1 charles-antoine dedryver2 & maurice hullé2 1 pasteur institute, 25 et 28, rue du docteur roux, fr-75015 paris, france 2 institute for genetics, environment and plant protection, french national institute for agricultural research, domaine de la motte, fr-35653 le rheu, france keywords natural enemies; introduced species; biological invasion; colonization; zygomycetes; parasitism. correspondence maurice hullé, institute for genetics, environment and plant protection, french national institute for agricultural research, domaine de la motte, fr-35653 le rheu, france. e-mail: maurice.hulle@rennes.inra.fr abstract since the 20th century, the sub-antarctic islands have suffered an increasing number of biological invasions. despite the large number of publications on this topic, there is a lack of knowledge on parasitism rates of invasive species and on the role of parasites and pathogens to regulate their populations. six aphid species have been introduced in the archipelagos of crozet (île de la possession, 468 25’ s�518 51’ e) and kerguelen (498 21’ s�708 13’ e). five of these species were found infected by entomopathogenic fungi of the order entomophthorales. all these fungal species are cosmopolitan. conidiobolus obscurus and entomophthora planchoniana were the most frequently observed on île de la possession and in archipel des kerguelen, respectively. this is the first report of pathogenic fungi of aphids on the sub-antarctic islands. we discuss these results in the light of our current knowledge of these insect pathogens. their introduction by aphids surviving on plants during transportation is the most likely hypothesis to explain their presence on these remote islands. as insular ecosystems in isolated and severe climatic environments, the sub-antarctic archipelagos of crozet and kerguelen provide a unique field to address questions regarding invasive species in relation to increasing human impact and climate change (gaston et al. 2002; chown et al. 2005; frenot et al. 2005; chown et al. 2008). these remote islands have a cold oceanic climate and a depauperate native fauna and flora. whalers and sealers were the main visitors during the 19th century and may be responsible for the first biological introductions. kerguelen was increasingly visited from the beginning of the 20th century, whereas for île de la possession, in the archipel crozet, the increase in visits began in the mid20th century (frenot et al. 2001; lebouvier & frenot 2007). as sub-antarctic islands, their food webs are poorly developed, with a high number of decomposers and very few herbivores, predators and parasites (crafford et al. 1986; chown et al. 1998; vernon et al. 1998; convey 2001). the success of invasive species in their new habitats can be explained at least in part by reduced control by natural enemies such as predators, pathogens and parasites*the enemy release hypothesis (colautti et al. 2004; liu & stiling 2006)*but also by their own biological traits, such as dispersal, fitness and so on (hayes & barry 2008). however, there is a lack of knowledge about parasitism rates of invasive species and the role of parasites and pathogens in regulating their populations (torchin et al. 2003; prenter et al. 2004; dunn et al. 2012). six species of aphids (hemiptera, aphididae) are known to occur on île de la possession and in archipel des kerguelen (remaudière & etienne 1988; hullé, pannetier, maurice et al. 2003): aulacorthum solani (kaltenbach), macrosiphum euphorbiae (thomas), myzus ascalonicus doncaster, myzus ornatus laing, myzus persicae (sulzer) and rhopalosiphum padi (l.). these species are cosmopolitan and are understood to have been introduced within the last 80 years (hullé, pannetier, simon et al. 2003). myzus ascalonicus is the most invasive (hullé, pannetier, simon et al. 2003; hullé 2012). this generalist feeder has colonized both introduced and native plants belonging to 14 families, and has spread widely, preferentially along the littoral zone and below 100 m above sea level (hullé, pannetier, simon et al. 2003). to understand major biological traits that influence colonization success by polar research 2016. # 2016 b. papierok et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 28765, http://dx.doi.org/10.3402/polar.v35.28765 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/28765 http://dx.doi.org/10.3402/polar.v35.28765 these cosmopolitan and polyphagous aphids in such subantarctic environments, studies were carried out starting from the end of the 1990s. host plant range, spatial and altitudinal distribution of aphids, their genetic variability, their role in the transmission of plant viruses and the vulnerability of native communities were especially investigated (delmotte et al. 2001; delmotte et al. 2003; hullé, pannetier, maurice et al. 2003; hullé, pannetier, simon et al. 2003; lebouvier et al. 2011; hullé 2012; svanella-dumas et al. 2013). aphids killed by fungi of the order entomophthorales (zygomycetes) sensu keller (2007) were first observed (by mh) in 2001 on île de la possession and in archipel des kerguelen, although the presence of natural enemies was not mentioned in the literature. the present contrizbution compiles observations of aphid-pathogenic fungi in archipel des kerguelen and on île de la possession and discusses these data in the framework of our current knowledge on these insect pathogens and invasion biology. material and methods archipel des kerguelen (498 21’ s�708 13’ e, 7200 km2) and île de la possession (468 25’ s�518 51’ e, 150 km2) in the archipel crozet are both in the sub-antarctic area of the southern indian ocean. their mean annual temperatures are 4.858c (météo-france, 1951�2014 records) and 5.528c (météo-france, 1970�2014 records), respectively; little seasonal variation is recorded. the major climatic difference between these two archipels is rainfall: the total annual rainfall is 2400 mm on île de la possession and varies from more than 3200 mm in the western part of archipel des kerguelen to less than 800 mm in the eastern part. entomophthorales-killed aphids were searched for during the austral growing seasons (december�may) in 2001/02 (île de la possession only) and 2011/12 and 2012/13 (île de la possession and archipel des kerguelen) at locations routinely used for botanical and entomological studies: base alfred faure, baie américaine, crique du sphinx, crique de noël and baie du la pérouse on île de la possession (fig. 1); and base de port-aux-français, île haute, île mayes, île aux cochons and île verte in archipel des kerguelen (fig. 2). such aphids can be recognized by their peculiar brownish colour and, sometimes, their fixation on the substrate through fungal structures called rhizoı̈ds or a layer of sporulating structures covering the body. when cadavers were found in aphid colonies, they were processed as follows to confirm the fungal nature of the infection and to identify the etiological agent. leaves bearing colonies were cut out and placed in containers not completely closed, to prevent the atmosphere from becoming saturated. back at the laboratory, leaves were observed with a binocular microscope. aphids killed by entomophthorales were gently removed from the leaf using forceps, and placed on a moistened piece of filter paper. that moistened piece was then attached to the inside of a petri dish and the lid was inverted on slides to collect conidia forcibly discharged from cadavers. following collection of conidia, slides were kept in dry conditions and corresponding cadavers stored in ethanol 70%. for observation of conidia, the slides were mounted in cotton blue in île de la possession ma: myzus ascalonicus rp: rhopalosiphum padi as: aulacorthum solani baie américaine conidiobolus obscurus: ma crique du sphinx conidiobolus obscurus: rp pandora neoaphis: rp zoophthora phalloides: rp, ma base alfred faure conidiobolus obscurus: ma, as conidiobolus coronatus: ma zoophthora phalloides: ma zoophthora sp: ma crique de noël conidiobolus obscurus: ma baie du la pérouse conidiobolus obscurus: ma fig. 1 distribution of entomophthorales on île de la possession (archipel crozet). aphid-pathogenic entomophthorales in the sub-antarctic b. papierok et al. 2 (page number not for citation purpose) citation: polar research 2016, 35, 28765, http://dx.doi.org/10.3402/polar.v35.28765 http://www.polarresearch.net/index.php/polar/article/view/28765 http://dx.doi.org/10.3402/polar.v35.28765 lactophenol. shapes of spores were systematically noted, and the length and width of 10�50 spores per cadaver were measured, using a light microscope (200�). cadavers kept in ethanol were also mounted in anilin blue or cotton blue in lactophenol after being teased apart using fine forceps or fine insect pins for observation and measurement of possible resting spores; detailed procedures are described by, for example, papierok and balazy (2007). the fungal species were identified on the basis of the combination of the following phenotypic characters: shape and size of primary and possibly secondary conidia, branched or unbranched conidiophores, shape and size of resting spores, and presence and type of rhizoids (latgé & papierok 1988; keller 2006; keller 2007). results a total of 114 fungus-killed aphids were collected: 98 myzus ascalonicus, seven rhopalosiphum padi, seven aulacorthum solani and two macrosiphum euphorbiae. the distribution of entomophthoralean species and their aphid hosts are shown in figs. 1, 2 and table 1. six different entomophthorales were distinguished from dead aphids collected on île de la possession, namely: conidiobolus obscurus (hall & dunn) remaudière & keller (in 2001�02 and 2011�13); entomophthora planchoniana cornu (in 2001�02); pandora neoaphidis (remaudière & hennebert) humber (in 2001�02); zoophthora phalloides batko (in 2001�02); zoophthora sp. (in 2001�02); and conidiobolus coronatus (costantin) batko (in 2011�13). in archipel des kerguelen, only two species were observed (in 2011�13): entomophthora planchoniana and conidiobolus obscurus. the principal morphological characteristics of these fungal species are given in table 2, together with the sizes of the locally collected corresponding spores. conidiobolus obscurus was found on myzus ascalonicus, aulacorthum solani and rhopalosiphum padi, but the situation differed between the two regions. on île de la possession, c. obscurus was observed on both periods of collection and was the main aphid pathogen at the five studied locations (57 out of 68 aphids), especially on m. ascalonicus (49 specimens out of a total of 55). in archipel des kerguelen, c. obscurus was found at three out of the base de port-aux-français archipel des kerguelen île aux cochons île verte île mayes île haute entomophthora planchoniana: ma, me conidiobolus obscurus: ma entomophthora planchoniana: ma conidiobolus obscurus: rp entomophthora planchoniana: ma conidiobolus obscurus: ma entomophthora planchoniana: ma ma: myzus ascalonicus rp: rhopalosiphum padi me: macrosiphum euphorbiae fig. 2 distribution of entomophthorales in archipel des kerguelen (golfe du morbihan). table 1 the entomophthorales and their aphid hosts. numbers correspond to the number of collected aphids: in boldface 2001�02; in roman: 2011�13). île de la possession archipel des kerguelen entomophthorales myzus ascalonicus aulacorthum solani rhopalosiphum padi myzus ascalonicus macrosiphum euphorbiae rhopalosiphum padi conidiobolus coronatus 1 conidiobolus obscurus 27�22 7 1 5 1 entomophthora planchoniana 3 38 2 pandora neoaphidis 2 zoophthora phalloides 1 3 zoophthora sp. 1 total 55 7 6 43 2 1 b. papierok et al. aphid-pathogenic entomophthorales in the sub-antarctic citation: polar research 2016, 35, 28765, http://dx.doi.org/10.3402/polar.v35.28765 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/28765 http://dx.doi.org/10.3402/polar.v35.28765 five studied locations, on m. ascalonicus and r. padi only, and there were fewer of them (six out of 46 aphids). as for c. obscurus, the situation regarding entomophthora planchoniana differed between the two regions. on île de la possession, the fungus was found at one location during one period of collection (2001�02) and on three specimens of m. ascalonicus. by contrast, in archipel des kerguelen, e. planchoniana was observed at four out of the five locations, and was the main aphid pathogen (40 specimens out of 46), mainly on m. ascalonicus (38 specimens), and twice on m. euphorbiae at one location. aphids parasitized by c. obscurus and e. planchionana were found continuously between december and may, suggesting that the infection persisted over several aphid generations. pandora neoaphidis was collected only at crique du sphinx (île de la possession) in 2001�02 on two specimens of r. padi. zoophthora phalloides was observed on île de la possession at two of the five studied locations, on four specimens only: three r. padi and one m. ascalonicus. from the single m. ascalonicus specimen found infected by z. phalloides, another type of primary and secondary conidia typical from the genus zoophthora was observed. unfortunately very few conidia were obtained. that material resembled zoophthora radicans (brefeld) batko, but the poverty of our collection could not allow a proper identification. the fungus was therefore referred to as zoophthora sp. conidiobolus coronatus was found on one occasion only on île de la possession, on m. ascalonicus. discussion entomophthorales are considered as the main fungal pathogens of aphids throughout the world (latgé & papierok 1988; pell et al. 2001; barta & cagáň 2006). the present work is the first report of any aphid-pathogen member of that fungal group on the sub-antarctic islands. one species of the genus neozygites, parasitizing mites, was recorded in the west coast of antarctica (bridge & worland 2004). the situation appears similar in the arctic, where these fungi have been very rarely observed: on aphids in finland north of the arctic circle (papierok 1989), on muscoid flies in greenland (eilenberg et al. 2007) and in larval populations of a noctuid moth in west greenland (avery & post 2013). except for zoophthora sp., the main characteristics of the five other identified entomophthoralean species match overall the data from the literature. however, slight differences in the size of primary conidia (conidiobolus obscurus) or length of capilliconidia (z. phalloides) were observed compared to the literature (remaudière et al. 1979; bałazy 1993; keller 2006), underlining the morphological variation within these species. conidiobolus obscurus and entomophthora planchoniana, the two species most frequently found in the subantarctic archipel des kerguelen and île de la possession, table 2 the six entomophthoralean species found on aphids in crozet and kerguelen archipelagos: main morphological characteristics and corresponding spore sizes of the local collected material. entomophthoralean species main morphological characteristics primary conidia extreme length �extreme width in mm secondary conidia length �width in mm resting spores in mm conidiobolus obscurus unbranched conidiophores, absence of rhizoids, almost globose primary conidia, spherical resting spores 32.7�45.7 �32.3�40.7 mean: 40.1 �34.5 � diameter: 34.1�34.7 wall thickness: 2.4�3.3 entomophthora planchoniana unbranched conidiophores, thick rhizoids, subspherical campanulate conidia, resting spores with dark, uneven epispore 16.7�19.0 �15.1�16.2 mean: 18.3 �14.7 � no resting spores observed pandora neoaphidis branched conidiophores, thin rhizoids with discoid holdfast, primary conidia ovoid to elongate ovoid, absence of resting spores 21.1�25.0 �12.6�14.9 � � zoophthora phalloides branched conidiophores, thin rhizoids with specialized holdfast, long and slim primary conidia, with a papilla demarcated with a light bulge from the conidial body, capilliconidia 33.4�35.1 �8.7�8.9 31.9 �8.7 no resting spores observed zoophthora sp. id. but ellipsoid primary conidia 22.8 �10.8 23.1 �7.5 no resting spores observed conidiobolus coronatus unbranched conidiophores, absence of rhizoı̈ds, almost globose primary conidia, absence of resting spores, presence of villose conidia 41.2 �36.1 � aphid-pathogenic entomophthorales in the sub-antarctic b. papierok et al. 4 (page number not for citation purpose) citation: polar research 2016, 35, 28765, http://dx.doi.org/10.3402/polar.v35.28765 http://www.polarresearch.net/index.php/polar/article/view/28765 http://dx.doi.org/10.3402/polar.v35.28765 are two of the three most frequent and numerous pathogens in aphid populations in temperate and continental climates (thaxter 1888; shands et al. 1963; gustafsson 1965; remaudière, latgé et al. 1981; pell et al. 2001). the third species, p. neoaphidis, was in contrast found on one aphid species at one location only (île de la possession) during our investigations. one could hypothesize that this fungus was a late introduction that has not yet established itself across the archipelagos. in any case, the presence of c. obscurus in both periods of study, that is, at an interval of 10 years, shows the ability of entomophthorales to be established successfully in the sub-antarctic. entomophthora planchoniana is the most abundant species in archipel des kerguelen and c. obscurus on île de la possession. this difference in distribution could be explained by differences in rainfall between both locations, with annual rainfall much higher in crozet than in eastern kerguelen. in europe, e. planchoniana seems to be able to tolerate lower relative humidity than c. obscurus (dedryver 1981; remaudière, keller et al. 1981). a few hypotheses can be invoked to explain the presence of entomophthorales infecting aphids on subantarctic islands. first, all entomophthoralean species recorded could have been introduced, along with aphids, by people. zoophthora phalloides, for instance, is found only on aphids of the sub-family of aphidinae, to which belong m. ascalonicus and r. padi (remaudière, latgé et al. 1981), the most abundant aphid species introduced in crozet and kerguelen (hullé, pannetier, simon et al. 2003). introduction of fungi by aphids surviving on plant foods (e.g., onions for m. ascalonicus infected by z. phalloides) transported by boat appears as the most likely scenario. second, entomophthorales could have been introduced without human intervention by transient airborne winged aphids. transportation of entomophthorales by winged aphids is common, but infected aphids cannot fly actively long distances (feng et al. 2007) and must be transported passively by wind. longdistance passive flights by aphids (about 1300 km) have been mentioned to explain the presence of the aphid cinara abieticola cholodkovsky in svalbard (heikinheimo 1968). however, the nearest possible sources of infected aphids to colonize crozet and kerguelen are more than 3000 km away, so this hypothesis seems to be less probable that the previous one to explain the presence of entomophthorales (and of their hosts) in these archipelagos. third, some fungal species could have been present before the arrival of aphids, on other insects or in the soil. all but one of the entomophthoralean species found in this study are aphid-specific and seem only to survive some months in soil without any aphid host (latteur 1977). indeed, only conidiobolus coronatus is known to cause mortalities in other insect species (benze’ev & kenneth 1980; papierok & coremans-pelseneer 1980; papierok 1985; papierok et al. 1986; keller 1987). conidiobolus coronatus is mainly a saprophytic fungus that can be easily isolated from temperate and tropical soil samples. although possible, this third hypothesis has not been yet supported by observations of infected insect species other than aphids or the detection of fungal material in the soil. in conclusion, on the basis of the situation observed with the aphid�entomophthorale model in the insular ecosystems of the sub-antarctic archipelagos of crozet and kerguelen, the in-depth study of the introduction of these insects and their pathogens into such environments could contribute to a better understanding of the role of natural enemies in biological invasions (dunn 2009). acknowledgements this research was supported by the french polar institute (programme 136 subanteco) and the french national center for scientific research (zone atelier de recherche sur l’environnement antarctique et subantarctique). the french national institute for agricultural research and the pasteur institute are acknowledged. we also thank scientific volunteers who helped during fieldwork. references avery m. & post e. 2013. record of a zoophthora sp. (entomophthoromycota: entomophthorales) pathogen of the irruptive noctuid moth eurois occulta (lepidoptera) in west greenland. journal of invertebrate pathology 114, 292�294. balazy s. 1993. flora of poland. fungi (mycota). vol. 24. entomophthorales. krakow: institute of botany. barta m. & cagáň l. 2006. aphid-pathogenic entomophthorales (their taxonomy, biology and ecology). biologia 61, 543�616. ben-zéev i. & kenneth r. g. 1980. zoophthora phytonomi and conidiobolus osmodes, zygomycetes, entomophthoraceae, two pathogens of hypera species (col. curculionidae) coincidental in time and space. entomophaga 25, 171�186. bridge p.d. & worland m.r. 2004. first report of an entomophthoralean fungus on an arthropod host in antarctica. polar biology 27, 190�192. chown s.l., gremmen n.j.m. & gaston k.j. 1998. ecological biogeography of southern ocean islands: species�area relationships, human impacts, and conservation. american naturalist 152, 562�575. chown s.l., hull b. & gaston k.j. 2005. human impacts, energy availability and invasion across southern ocean islands. global ecology and biogeography 14, 521�528. b. papierok et al. aphid-pathogenic entomophthorales in the sub-antarctic citation: polar research 2016, 35, 28765, http://dx.doi.org/10.3402/polar.v35.28765 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/28765 http://dx.doi.org/10.3402/polar.v35.28765 chown s.l., lee j.e. & shaw j.d. 2008. conservation of southern ocean islands: invertebrates as exemplars. journal of insect conservation 12, 277�291. colautti r.i., ricciardi a., grigorovich i.a. & macisaac h.j. 2004. is invasion success explained by the enemy release hypothesis? ecology letters 7, 721�733. convey p. 2001. terrestrial ecosystem response to climate changes in the antarctic. in g.r. walther, c.a. burga, & p.j. edwards (eds.): ‘‘fingerprints’’ of climate change*adapted behaviour and shifting species ranges. pp. 17�42. new york: kluwer. crafford j.e., scholtz c.h. & chown s.l. 1986. the insects of sub-antarctic marion and prince edward islands; with a bibliography of entomology of the kerguelen biogeographical province. south african journal of antarctic research 16, 42�84. dedryver c.a. 1981. biologie des pucerons des céréales dans l’ouest de la france. ii. répartition spatio-temporelle et action limitative de trois espèces d’entomophthoraceae. (biology of cereal aphids in western france. ii. spatiotemporal distribution and limiting action of three species of entomophthoraceae.) entomophaga 26, 381�393. delmotte f., leterme n., bonhomme j., rispe c. & simon j.c. 2001. multiple routes to asexuality in an aphid species. proceedings of the royal society of london b 268, 2291�2299. delmotte f., sabater-muñoz b., prunier-leterme n., latorre a., sunnucks p., rispe c. & simon j.c. 2003. phylogenetic evidence for hybrid origins of asexual lineages in an aphid species. evolution 57, 1291�1303. dunn a.m. 2009. parasites and biological invasions. in j.p. webster (ed.): natural history of host�parasite interactions. pp. 161�184. san diego: elsevier. dunn a.m., torchin m.e., hatcher m.j., kotanen p.m., blumenthal d.m., byers j.e., coon c.a.c., frankel v.m., holt r.d., hufbauer r.a., kanarek a.r., schierenbeck k.a., wolfe l.m. & perkins s.e. 2012. indirect effects of parasites in invasions. functional ecology 26, 1262�1274. eilenberg j., schmidt n.m., meyling n. & wolsted c. 2007. preliminary survey for insect pathogenic fungi in arctic greenland. iobc/wprs bulletin 30, 12. feng m., chen c., shang s.i., ying s., shen z. & chen x. 2007. aphid dispersal flight disseminates fungal pathogens and parasitoids as natural control agents of aphids. ecological entomology 32, 97�104. frenot y., chown s.l., whinam j., selkirk p.m., convey p., skotnicki m. & bergstrom d.m. 2005. biological invasions in the antarctic: extent, impacts and implications. biological reviews 80, 45�72. frenot y., gloaguen j.c., massé l. & lebouvier m. 2001. human activities, ecosystem disturbance and plant invasions in subantarctic crozet, kerguelen and amsterdam islands. biological conservation 101, 33�50. gaston k.j., chown s.l. & bradley p. 2002. invertebrate diversity and endemism at gough island and threats from introduced species. final project report. project ref. 162/8/253. sheffield: department of animal and pland sciences, university of sheffield. gustafsson m. 1965. on species of the genus entomophthora fres. in sweden. i. classification and distribution. lantbrukshögskolans annaler 31, 103�212. hayes k. & barry s. 2008. are there any consistent predictors of invasion success? biological invasions 10, 483�506. heikinheimo o. 1968. the aphid fauna of spitsbergen. annales entomologici fennici 34, 82�93. hullé m. 2012. myzus ascalonicus, an aphid recently introduced to sub-antarctic islands, prefers native to exotic host-plants. environmental entomology 41, 1398�1404. hullé m., pannetier d., maurice d., courmont l., chaillon c., chaillon p.-e., saccone p., hébert c., gracia m., buffin j., simon j.-c. & frenot y. 2003. aphids from kerguelen and crozet islands, subantarctic. in a.h.l. huiskes et al. (eds.): antarctic biology in a global context. pp. 308�312. leiden: backhuys publishers. hullé m., pannetier d., simon j.-c., vernon p. & frenot y. 2003. aphids of sub-antarctic îles crozet and kerguelen: species diversity, host range and spatial distribution. antarctic science 15, 203�209. keller s. 1987. arthropod-pathogenic entomophthorales of switzerland. i. conidiobolus, entomophaga and entomophthora. sydowia 40, 122�167. keller s. 2006. entomophthorales attacking aphids with a description of two new species. sydowia 58, 38�74. keller s. 2007. systematics, taxonomy and identification. in s. keller (ed.): arthropod-pathogenic entomophthorales: biology, ecology and identification. pp. 111�126. luxembourg: office for official publications of the european communities. latgé j.p. & papierok b. 1988. aphid pathogens. in a.k. minks & p. harrewijn (eds.): aphids: their biology, natural enemies and control. pp. 323�335. amsterdam: elsevier. latteur g. 1977. sur la possibilité d’infection directe d’aphides par entomophthora à partir de sols hébergeant un inoculum naturel. (the possibility of direct infection of aphids by entomophthora from soil natural inoculum.) comptes rendus des séances de l’académie des sciences de paris 284, 2253�2256. lebouvier m. & frenot y. 2007. conservation and management in the french sub-antarctic islands and surrounding seas. papers and proceedings of the royal society of tasmania 141, 23�28. lebouvier m., laparie m., hullé m., marais a., cozic y., lalouette l., vernon p., candresse t., frenot y. & renault d. 2011. the significance of the sub-antarctic kerguelen islands for the assessment of the vulnerability of native communities to climate change, alien insect invasions and plant viruses. biological invasions 13, 1195�1208. liu h. & stiling p. 2006. testing the enemy release hypothesis: a review and meta-analysis. biological invasions 8, 1535� 1545. papierok b. 1985. données écologiques et expérimentales sur les potentialités entomopathogènes de l’entomophthorale conidiobolus coronatus (costantin) batko. (ecological and experimental data on the insect pathogenic potential of the entomophthorale conidiobolus coronatus.) entomophaga 30, 303�312. aphid-pathogenic entomophthorales in the sub-antarctic b. papierok et al. 6 (page number not for citation purpose) citation: polar research 2016, 35, 28765, http://dx.doi.org/10.3402/polar.v35.28765 http://www.polarresearch.net/index.php/polar/article/view/28765 http://dx.doi.org/10.3402/polar.v35.28765 papierok b. 1989. on the occurrence of entomophthorales in finland. i. species attacking aphids (homoptera, aphididae). annales entomologici fennici 55, 63�69. papierok b., aeschlimann j. p. & loan c. 1986. two entomophthoralen fungi occuring on hypera postica in southern france. journal of invertebrate pathology 48, 377�380. papierok b. & balazy s. 2007. collecting arthropod-pathogenic entomophthorales: how to find them in the field and how to collect, prepare and store the appropriate material for classical identification purpose? in s. keller (ed.): arthropodpathogenic entomophthorales: biology, ecology and identification. pp. 57�65. luxembourg: office for official publications of the european communities. papierok b. & coremans-pelseneer j. 1980. contribution á l’étude de conidiobolus osmodes dreschler (zygomycètes, entomophthoraceae), agent occasionel d’épizooties chez les pucerons (homoptères aphididae). (contribution to the study of conidiobolus osmodes drechsler [zygomycetes, entomophthora cae], occasional epizootic in aphids [homoptera aphididae].) cryptogamie mycologie 1, 111�117. pell j.k., eilenberg j., hajek a.e. & steinkraus d.c. 2001. biology, ecology, and pest management potential of entomophthorales. in t.m. butt et al. (eds.): fungi as biological agents: progress, problems and potential. pp. 71�153. wallingford: cabi publishing. prenter j., macneil c., dick j.t.a. & dunn a.m. 2004. roles of parasites in animal invasions. trends in ecology & evolution 19, 385�390. remaudière g. & etienne j. 1988. les aphididae (hom.) des ı̂les et archipels de l’océan indien. (aphididae [hom.] of the indian oceanic islands and archipelagos.) l’agronomie tropicale 43, 327�346. remaudière g., keller s., papierok b. & latgé j.-p. 1981. considérations systématiques et biologiques sur quelques espèces d’entomophthora du groupe pathogènes d’insectes (phycomyctes: entomophthoraceae). (systematic and biological considerations regarding some entomophthora species of insect pathogens [phycomyctes: entomophthoraceae].) entomophaga 21, 163�177. remaudière g., latgé j.-p. & michel m.f. 1981. ecologie comparée des entomophthoracées pathogènes de pucerons en france littorale et continentale. (ecology of aphid pathogenic entomophthorales in coastal and continental france.) entomophaga 26, 157�178. remaudière g., latgé j.-p. & papierok b. 1979. reconsidération taxonomique de entomophthora obscura hall & dunn. (taxonomic revision of entomophthora obscura hall & dunn. annales de microbiologie (institut pasteur) 130a, 151�162. shands w.a., simpson g.w. & hall i.m. 1963. importance of entomogenous aphids in controlling aphids on potatoes in northeastern maine. maine agricultural experimental station technical bulletin 6. orono: maine agricultural experiment station. svanella-dumas l., candresse t., hullé m. & marais a. 2013. distribution of barley yellow dwarf virus-pav in the subantarctic kerguelen islands and characterization of two new luteovirus species. plos one 8, e67231, doi: http://dx. doi.org/10.1371/journal.pone.0067231 thaxter r. 1888. the entomophthoreae of the united states. memoirs of the boston society of natural history 4(6), 133�201. torchin m.e., lafferty k.d., dobson a.p., mckenzie v.j. & kuris a.m. 2003. introduced species and their missing parasites. nature 421, 628�630. vernon p., vannier g. & trehen p. 1998. a comparative approach to the entomological diversity of polar regions. acta oecologica 19, 303�308. b. papierok et al. aphid-pathogenic entomophthorales in the sub-antarctic citation: polar research 2016, 35, 28765, http://dx.doi.org/10.3402/polar.v35.28765 7 (page number not for citation purpose) http://dx.doi.org/10.1371/journal.pone.0067231 http://dx.doi.org/10.1371/journal.pone.0067231 http://www.polarresearch.net/index.php/polar/article/view/28765 http://dx.doi.org/10.3402/polar.v35.28765 phytoplankton-bacteria relationship in the antarctic marine ecosystem gilles b l l l e n and sylvie becquevort billen, g . & becquevort, s. 1991: phytoplankton-bacteria relationship in the antarctic marine ecosystem. pp. 245-253 in sakshaug. e . . hopkins, c. c. e. & britsland. n. a . (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, 12-16 may 1990. polar research l o ( 1 ) . time series data of phytoplanktonic and bacterial biomass during the ice retreat period at different latitudes in the weddell sea and prydz bay areas show a distinct delay in the development of bacteria with respect to phytoplankton. use of a general ecophysiological model of bacterial growth, along with direct in situ measurements of growth and mortality rates, allowed the simulation of the observed timing of bacterial development. i t is suggested that the uncoupling between phytoplanktonic and bacterial development at the earliest stage of the spring ice-edge related algal bloom is not the result of the low temperatures occurring in the southern ocean but rather is due to the macromolecular nature of thc dissolved organic matter released from phytoplankton. gilles billen and syluie becqueuort. groupe de microbiologie des millieux aquatiques, university of brussels, c p 221. campus de la plaine, b-1050 brussels, belgium. introduction that planktonic bacteria directly depend on phy toplankton in aquatic systems devoid of alloch tonous input of organic matter is now widely recognized. evidence for this statement is pro vided by the correlation which exists between bacterial biomass and chlorophyll u concentration (linley et al. 1983; bird & kalff 1984) or between bacterial production and both chlorophyll u con centration and planktonic primary production (cole et a]. 1988), over a large range of temperate and tropical aquatic environments. however, the exact nature of the trophic relationship between phytoplankton and bacteria is still a matter of controversy. exudation by algae of low molecular weight photosynthates has long been considered as the dominant dissolved organic carbon (doc) flux to heterotrophic bacteria (larsson & hag strom 1979; wolter 1982; m d l e r jensen 1983). recently, however, bjgrnsen (1989) suggested that exudation should be interpreted as a passive leakage of small metabolites across cellular mem branes and should represent no more than 1 5% of phytoplankton biomass per day (0.0005 0.002 h-l). other processes producing doc therefore probably account for an additional and often dominant part of the organic matter transfer to the bacterial compartment, as e.g. direct lysis of phytoplankton cells (jassby & goldman 1974; billen 1984) or rapid diffusion from incompletely digested fecal material of macroor micrograzers (the so-called sloppy feeding of lampert 1978) (jumars et al. 1989). these processes mainly pro duce dissolved organic substances with high molecular weight which require extracellular hydrolysis before they can be taken up by bac terioplankton. for this reason, a looser coupling between bacteria and phytoplankton can be expected in situations where the latter processes of doc-supply are dominant rather than in situa tions where bacteria live mainly on algal exu dation products (billen 1990). how these ideas apply to polar systems at low temperatures is the subject of this paper. con tradictory observations have been published in previous literature concerning the role of bacteria in arctic and antarctic marine ecosystems. some authors (hodson et al. 1981; azam et al. 1981; hanson & lowery 1983; hanson et al. 1983; sullivan et ai. 1990) reported measurements of bacterial activities in the antarctic ocean of the same order of magnitude as those observed i n temperate seas. they concluded that the microbial loop performs a similarly important role in the antarctic marine system as in tem perate and tropical systems. on the other hand, situations with high phytoplanktonic biomass and low bacterial numbers and activities have been reported in both the arctic and antarctic systems (kriss et al. 1969; sorokin 1971; mullins & priddle 1987; davidson 1985; pomeroy et al. 1990). pomeroy & deibel (1986) explained this by a dramatic decrease of bacterial activity below 2”c, while algae continued to be active at these tem peratures. this could explain the preservation of doc, which has sometimes been found in high 246 g . billen & s. becqitevort concentrations in antarctic waters (bolter & dawson 1982). this organic matter would then be exported to lower latitudes by deep oceanic circulation (sorokin 1971). as observations of low bacterial activity most often concern early spring situations, a possible explanation reconciling these contradictory observations may be that a time lag exists in the response of bacterioplankton t o algal develop ment. only rather fine time-series observations could confirm this hypothesis. such time series are difficult to obtain, however, for obvious logistic reasons. in this paper we present such data on phytoplankton and bacterioplankton develop ment obtained during the period of ice retreat in two sectors of the antarctic ocean. we discuss them in the light of a simplified ecophysiological model of bacterioplankton development. biotopes and methods the two data sets used in this paper result from the participation of belgian teams, in an aus tralian cruise to prydz bay area (marine science voyage 7 of the australian antarctic division on board of the m / v n e l l a d a n ) and in the european epos cruise to the weddell sea, on board the r/v polarstern fig. 1). the prydz bay area was first visited in mid-january 1987 by joiris et al. ing the french indigo 111 cruise. at that time, the position of the ice edge was about 65"s. from mid february to end-march 1987, the area between 62 and 66"s was free of ice. in t h e weddell sea area, several successive transects along the meridian 49"w were sampled from mid-november 1988 to the beginning of january 1989. the ice edge location varied during this period from about 60"s to 61.5"s. chlorophyll a determinations were carried out according to lorenzen (1967). conversion into carbon biomass was made by using a constant c/ chlorophyll a ratio of 30. this represents the median value derived from comparison of chloro phyll a determination and algal carbon content calculated from microscopic cell size deter mination using edler's (1979) formulas (mathot pers. conim.). at most stations, samples were taken at 10,20, 40,60. and 120 m depth. the results reported here are the means of the duplicate determinations performed at the depths located in the upper (1987) on board the r / v m a r i o n d u f r e s n e dur krn fig. 1. the two areas in the southern ocean where the data sets discussed in this paper were collected. homogeneous layer, as determined from the ctd vertical profile (range 15-5011-1). for only a few stations, samples were only taken at 10 m depth. in these cases the results reported are the means of the duplicate determinations. bacteria were enumerated by epifluorescence microscopy after either acridine orange (hobbie et al. 1977) (prydz bay data) or dapi staining (porter & feigh 1980) (weddell sea data). bio volumes were estimated on enlargements of microphotographs. conversion into carbon bio mass was done using the biovolume dependent c/biovolume ratio proposed by simon & azam (1989). differences in the bacterial biomass val ues reported here for the prydz bay area with previously reported values (lancelot et al. 1989) originate from the use of this new conversion factor. bacterial production rates were measured according to the 3h-thymidine incorporation method of fuhrman & azam (1982). 3h-thy midine was added at a final concentration of 10 nmol i ' , a concentration shown saturating for the process of incorporation. the uptake of radioactivity in the cold tca fraction was deter mined after 3-4 hours incubation. empirical cali bration with cell number increase in 0.2ym filtered seawater reinoculated with 2 p n filtered water (riemann et al. 1987) was carried out sev eral times at both sites. the conversion factors phytoplankton-bacteria relationship 241 da. iaa.31 were 5.0.10' and 1.25. lo9 cells/nmol thymidine incorporated in the prydz bay area and the wed dell sea, respectively. maximum growth rate of bacteria was measured after addition of a mixture of amino acids and monosaccharides in the following final concentrations: glucose (4 mg i i ) , galactose (4 mg i-'), casamino acids (15 mg i [ ) , am monium acetate (1.5 mg ]-'), ammonium hydro genophosphate (2.5 mg 1-i). bacterial mortality was estimated according to the method developed by servais et al. (1985, 1989). the part of grazing in overall mortality rate was estimated by comparing the mortality rate of an untreated sample with a sample filtered through a 2 p m membrane and treated with a colchicine and cycloheximide (concentration 100 and 200 mg i-', respectively) (becquevort et al. unpublished data). results and discussion relationship between bacterial and phytoplanktonic biomass when plotted against each other, no distinct relationship is apparent between bacterial and phytoplankton biomass (fig. 2a) as would be expected in the case of a direct response of bac teria to phytoplankton. data from successive situations in the same area, however, describe counterclockwise trajectories, indicating that phytoplankton development precedes bacterial response by about 15-30 days (fig. 2b). this "1 0 % 1 0 i chlorophyll a, pg.1-l fig. 2 a . bacterial biomass plotted against chlorophyll a values in the weddell sea (0) and prydz bay ( 0 ) area during the period of ice retreat. weddell sea 590503 49ow dec. 1-20 nor. 26-34 1 2 chlorophyll a, pg.1-i weddell sea 5 9 6 49ow 7 k. 1-10 & da. 1-10 nor. -0 s .j 10. e 3 f . pry& bay 7 chlorophyll a, pg.1-i fig. 2 b . counterclockwise trajectories of bacterial and phy toplankton biomass values at 3 sites in the southern ocean. the counterclockwise trajectories indicate a delayed response of bacteria to algal development. 248 delay in the bacterial response to phytoplankton is quite clear in the prydz bay data set, which shows a clear chlorophyll maximum in mid-janu ary, while bacterial biomass peaks only about o n e month later (fig. 3 ) . in the weddell sea data s e t , a delay is also quite apparent in the response of bacteria to the algal bloom which follows the southward retreat of the ice edge (fig. 4). g . billen & s . becquevort growth and mortality rates of bacterioplankton specific growth rate of bacteria, as estimated by the ratio between thymidine incorporation measurements during 4 hours incubation at in situ temperature and bacterial biomass, varied between 0.05 and 0.001 h l . a n immediate increase of this growth rate was observed when amending the samples with a mixture of amino acids and monosaccharides at a final concen trationof 10 mgc i ' and a c : n : p ratio of 1 6 : 4 : 1 by weight. w e considered that the value of the specific growth rate measured with this amend ment represents the maximum growth rate of the natural bacterial assemblage. use of short incubation times ( 4 hours) minimises the risk of modifications in the bacterial populations. fig. 5 shows the value of this maximum growth rate measured at different incubation tempera ture for samples from the weddell sea and the prydz bay area. also shown a r e the results of similar measurements carried o u t in the belgian coastal zone of the north sea (billen 1990). clearly, the temperature range of the southern prydzbay 63-666 0 0 2 0 -z 0 0 0 0 january february march fig. 3. temporal variations of chlorophyll a ( 0 ) and bacterial biomass (0) during the 1987 ice-retreat period in an area off prydz bay between 62 and 64"s. 5 3, (i 1 0 4 , ol weddell sea (490w) nov 2&30,1988 & c 0 weddell sea (490w) nov 2&30,1988 h 15 0 fig 4 . n-s iransects of chlorophyll a ( 0 ) and bacterial biomass (0)valuesobserved at different tirnesduringthe 1989ice retreat period in the weddell sea area (meridian 49"w). ocean ( 2 t o + 2 t ) is suboptimal for bacterial growth, in contrast t o what is observed for phy toplankton growth (see e.g. lancelot et al. 1989). nevertheless, when compared with the tem perature response of bacterial communities at temperate latitudes, a remarkable adaptation t o lower temperatures is found in antarctic bacteria, with an optimum temperature 18°c lower with respect to the former. antarctic bacteria a t nega tive temperatures a r e able to grow as fast as north sea bacteria in early spring conditions (8-10°c). measured rates of bacterial mortality in the two areas studied a r e remarkably constant, v'irying between 0.002 and 0.005 h ' in the range 2 t o +2"c. a clear effect of temperature o n mortality rate has been observed (fig. 6). grazing by proto phytoplankton-bacteria relationship 249 temperature, 0c fig. 5. maximum specific growth rate of natural assemblages of antarctic bacteria as determined by short term thymidine incorporation measurement after amendment with direct mono meric substrates. as a function of incubation temperature. 0 = prydz bay; w = weddell sea. also shown are the results of similar determinations carried out on bacterial assemblages from the southern bight of the north sea ( a ) . zoans contributed to 22 t o 100% of the total bacterial mortality. modelling bacterial response to phytoplankton development in order to better understand the causes of the delay observed in the bacterial response to phytoplanktonic development in the antarctic ecosystem, we used an idealised model of bac terioplankton dynamics, described and justified in details elsewhere (servais 1986; billen & fon tigny 1987; billen & servais 1989; billen 1991). the basic assumption of this model is that bac terial growth rate is directly dependent on the concentration of small, monomeric substrates, while most of the doc is under the form of macromolecules requiring extracellular hydroly sis. uptake of direct substrates is assumed to obey an overall michaelis-menten kinetics (parsons & strickland 1962; wright & hobbie 1965). a constant fraction y of the amount of substrate taken up is used for biomass production, the remaining part being respired (servais 1986). extracellular hydrolysis of biopolymers was also shown to obey a michaelis-menten kinetics (som ville & billen 1983; somville 1984). bacterial exoenzymes are mostly attached to bacterial envelopes and are present in constant amount with respect to biomass (fontigny et al. 1987). servais (1986) showed that it is possible to des cribe the bacterial utilisation of phytoplanktonic derived organic matter by assuming that it is made of two fractions ( h i , h z ) with different sus ceptibilities to extracellular hydrolysis, hence dif ferent parameters of their michaelis-menten degradation kinetics. the process of bacterial mortality can be represented, as a first approxi mation, by a first order kinetics (servais et al. 1985). the following equations can therefore be writ ten for describing the dynamics of bacterial growth: b ds _ hi + khi dt -elmax db s = yb,,, b k d b dt s + k, (4) where elmax, ezmax are the maximum rates of polymers hydrolysis per unit bacterial biomass; k h i , kh2 are the half-saturation constants of polymer hydrolysis; ph1, ph2 are the rate of production of poly mers through phytoplankton lysis; bmax is the maximum rate of substrate uptake by bacteria; ks is the half-saturation constant of sub strate uptake; y is the growth yield; kd is the mortality constant; pex is the rate of production of direct monomeric substrate through phy toplankton exudation. the value of most of the parameters involved in these equations has been determined experi mentally. from the data shown in fig. 5, the maximum growth rate of bacteria (pmax), and its temperature dependency can be estimated as follows: pmax(t) = 0.18 h ' * 0.1 + 0.9* { topi = 12°c exp [ (s)2]} ti topt with ti = 5°c 250 g . billen & s. becquevorr b 0 0 m 20 ternperature,'c fig. 6. grazing rate of natural bacterial assemblages of the weddell sea (0) and the prydz bay (d) as a function of temperature. t h e value of y . in the absence of nutrient limitation, is generally close to 0.3 (servais et al. 1987). b,,, is calculated as h a x / y . k, is taken arbitrarily as 0.01 mgc i i , as this parameter does not significantly influence t h e results of the cal culations. t h e parameters characterising the rate of exoenzymatic hydrolysis of macromolecules from phytoplanktonic origin have been estimated as follows, o n the basis of experiments in which the kinetics of bacterial degradation of a sonicated and filtered algal culture is measured after inocu lation with a natural assemblage of bacteria (ser vais 1986; billen 1990): e l m a x (top,) = 0.75 h ' , k h , = 0.1 mgc.1-i ermax(topt) = 0.25 h ' , kh2 = 2 . 5 mgc.1-i the same dependence t o temperature ( t ) as described above for pmax has been considered. o n the basis of experimental determinations of the total mortality rate constant kd, the following relationship with temperature has been considered: k d = 0.004 h ' + 0.0005 h l . t. o n the other hand, it has been assumed that organic matter is produced by phytoplankton through two distinct processes: (i) exudation, pro ducing low molecular weight substrates ( s ) a t a rate proportional t o its biomass (kc,); and (ii) lysis and/or sloppy feeding, producing high molecular weight biopolymers of two classes of utilisability ( h i , h z ) in a ratio 1 : 1. in t h e basic simulation, k,, has been maintained a t t h e lowest value sug gested by b j ~ r n s e n (1989) (0.0005 h-l). t h e rate of d o c production through lysis or sloppy feed ing is t h e only adjustable parameter of the model. forcing functions for the simulation a r e the observed variation of water temperature and phytoplankton biomass. figure 7 shows that t h e general trends of the observed bacterioplanktonic response to phyto plankton development both in prydz bay and in the weddell sea can be satisfactorily simulated with a single value of the first o r d e r rate constant of macromolecular doc production by phyto plankton (kly, = 0.004 h l ) . in particular t h e model predicts a lag of about 10 t o 30 days between the peaks of algal and bacterial biomass, as observed. t h e rates of bacterial production calculated by the model a r e compared in fig. 8 with the measured values. agreement is generally within a factor of 2, and again, the major trends of geographical and seasonal variations a r e correctly simulated. a s t h e measurements of bacterial bio mass and production rates are quite independent of each other, this overall agreement constitutes a further validation of the model. in order to obtain further insight into the factor responsible for the time lag between phyto plankton and bacterioplankton, the effect of vary ing some parameters or forcing variables in the model were tested. fig. 9 shows the effect of increasing t h e temperature to a constant value of 5°c: the timing of the bacterial development is hardly modified. o n t h e o t h e r hand, if the rate k,, of algal exudation of low molecular weight d o c is increased (at t h e expense of the pro duction rate of macromolecular material, klyt), the model predicts a much more rapid bacterial response. conclusion our observations in the prydz bay and weddell sea areas have shown clearly that a significant time lag exists in the response of bacterioplankton to the early spring phytoplankton development. application of our model of bacterioplankton phytoplankton-bacteria relationship 251 . weddell sea(l9aw) "1 weddellsea(49.w) 1% jan feb mar 5o 59dijs 25 0 4 61405 [25 \ . / 0 , , o 5 6 2 6 10 0 , * . 63-666 a j , , sa, 0 0 nov dec jan feb m a r apr fig. 7. simulation of the seasonal variations of bacterial biomass in response to observed phytoplankton development (dotted curve) at different latitudes. according to the hsb model, for a single value of the rate of phytoplankton macromolecular doc release (klyr = 0.004 h ' ) and a rate of phytoplankton exudation of 0.0005 h ' . the black dots represent the observed values of bacterial biomass. 0 nov dec jan feb mar . 59030s . a 6 0 6 1 4 b 'l1 fi0030s 6 1 6 .05 61030s . 0 . .05 6 2 6 0 , '1 prydzbay 63-666 0 i , , ,a, nov dec jan feb mar fig. 8. simulation of the seasonal variations of bacterial pro duction rate in response t o observed phytoplankton dev elopment (dotted curve) at different latitudes, according to the hsb model, for the same values of the parameters as in fig. 7. the black dots represent the observed values of bacterial production rates. dynamics, with measured values of the kinetic parameters involved, suggests that this time lag is not the result of a reduction of bacterial activity due to low temperatures. the fact that doc produced by phytoplankton is mostly under the form of macromolecular material requiring extra cellular hydrolysis before being taken up by bac terioplankton is a more likely explanation. 252 g. billen & s. becqueoort i 1 i november december january the occurrence of a delay between phyto plankton and bacterioplankton development does not, therefore, appear to be a specific feature of polar systems. accordingly. a similar, though shorter delay in bacterioplankton response to the spring phytoplankton bloom has been also described in temperate marine ecosystems (billen 1990; billen et al. 1990). acknowledgements. -this work is part of the belgian scientific research programme on antarctica. funded by the science policy office ( b n s s ~ s . belgium). under contract nr antar/ 05. the authors are indebted to the australian antarctic div ision for invitation to take part in marine science voyage 7 to prydz bay (1987). data from the weddell sea were collected during the european polarsfern study (epos) sponsored by the european science foundation and the alfred wcgener institute for polar and marine research. references azam. f.. ammerman. j w . & cooper. n. 1981: bacterio plankton distrihutional patterns and metabolic activities in the scotia sea. a n f . 1. u.s. 16. 16&165. billen. g . 1984: heterotrophic utilization and regeneration of nitrogen. pp. 31?-355 in hobble. j . e. & williams. p. j . le b. (eds.): heferofrophic acfiuify i n rhe sea. plenum press. billen, g . 1990: delayed debelopment of bacterioplankton with respect to phytoplankton: a clue for understanding their trophic relationships. arch. hydrobiol. beih. ergebn. limnol. 1 1 4 . 415-429. fir. 9. simulation of the effect of temperature b) and nature of thc organic matter released by phytoplankton c) on the dynamics of bacterioplankton development in thc weddell sea. a) basic simulation. as in fig. 7. k,,, = 0.004 h ' ; k,, = 0.0005 h ' observed in situ temperature. b) simulation of the effect of increasing the temperature up to 5°c. c) simulation of increased proportion of algal exudation in d o c release: k,,, = o.olm5 h ' ; k,, = 0.om hobserved i n situ temperature. billen. g . 1991: protein degradation in aquatic environments. chap. 7. pp. 122-142 in chrost. r . (ed.): enzymes in aquafic enoironmenrs. springer verlag. billen. g . & fontigny. a. 1987: dynamics of phaeocysris dominated spring bloom in belgian coastal waters. 11. bac terioplankton dynamics. mar. ecol. prog. ser. 37, 24'+257. billen, g. & servais. p. 1989: modelisation des processus de degradation de la matierc organique en milieu aquatique. pp. 21%245 in bianchi. m. et al. (eds.): micro-organtimes dans les ecosysremes oceaniques. masson. paris. billen. g . . joiris. ci.. meyer-reil. l. & lindebloom. m . 1990: rble of bacteria in the north sea ecosystem. nerh. j. sea res. 26. 265-293. bird. d. e. & kalff, j . 1984: empirical relationship between bacterial abundance and chlorophyll concentration in fresh and marine waters. can. j . fish aq. sci. 41, 15-1023. bjarnsen. p. k. 1989: phytoplankton exudation of organic matter: why d o healthy cells d o it? limnol. oceanogr 33. 151-154. bolter. m. & dawson, r. 1982: heterotrophic utilization of biochemical compounds in antarctic waters. nefh. j . sea r e s . 16. 315-332. cole. j . c.. findlay. s. & pace. m. l. 1988: bacterial pro duction i n fresh and saltwater ecosystems: a cross-system overview. mar. e d . prog. ser. 43. 1-10. davidson. a . t . 1985: aspects of the biology of phaeorysris pouchefii. thesis, university of tasmania. hobart, australia. 231 pp. edler. l. 1979: recommendations for marine biological studies in the baltic sea. phytoplankton and chlorophyll. bdrzc marine biologisfs 5 . 1-38. fontigny. a , , billen. g . & vives rego. j. 1987: some kinetics characteristics of exoprotcolytic activity in coastal sea water. coasf esf. mar. sci. 2 5 . 127-134. phytoplankton-bacteria relationship 253 fuhrman. j . a . & azam. f. 1982: thymidine incorporation area measure of heterotrophic bacterioplankton evaluation in marine surface waters: cvaluation and field result. mar. biol. 66, 109-120. hanson. r . b . & lowry, h . k. 1983: nucleic acid synthesis in oceanic microplankton for the drake passage. antarctica. evaluation of steady-state growth. mar. biol. 73. 79-89. hanson. r . 8.. shafer. d., ryan, t . , pope, d. h. & lowry. h. k. 1983: bacterioplankton in antarctic ocean waters during late austral winter: abundance, frequency of dividing cells and estimates of production. appl. enuiron. microbiol hobbie, j . e . , daley, r. j . &jasper, s. 1977: use ofnuclepore filters for counting bacteria by fluorescence microscopy. appl. enuiron. microbiol. 33, 1225-1228. hodson, r . e., azam, f., carlucci, a. f., fuhrman. j. a , . karl, d . m. & holm-hansen. 0. 1981: microbial uptake of disolved organic matter in mcmurdo sound, antarctica. mar. biol. 61, 89-94. jassby. a. d. & goldman. c. r. 1974: loss rates from a lake phytoplankton community. limnol. oceanogr. 19. 618-627. joiris, c . , overloop. w., frankignoulle. m. & bouquegneau, j . m. 1987: preliminary discussion of the results obtained in antarctica during the austral summe; 1986-1987: plankton ecology and ecotoxicology. in proceedings of fhe belgian colloquium on antarcfic research, brussels, ocf. 20. 1987. prime minister's services. science policy office. jumars, p. a.. penry, d. l.. baross, j. a.. perry. m. j. & frost, b. w. 1989: closing the microbial loop: dissolved carbon pathway to heterotrophic bacteria from incomplete ingestion. digestion and absorption in animals. deep-sea res. 36, 48s495. kriss. a . e . , mishustina. 1. e.. lebedeva. m. n. 1969: bacterial population densities (heterotrophus) in the water column of the southern and indian oceans. mikrobiologyia 38. 51 1 517. lampert, w. 1978: release of dissolved organic carbon by grazing zooplankton. limnol. oceanogr. 3 , 831-834. lancelot. c., billen. g. & mathot. s. 1989: ecophysiology of phytoand bacterioplankton growth in the southern ocean, pp. 1-93 in caschetto. s . (ed.): belgian scientific research programme on antarcfica. scientific results of phase 1 (ocf 85-jan 89). vol. 1 . science policy office, brussels. belgium. larsson, u . & hagstrom. a . 1979: phytoplankton exudate release as an energy source for the growth of pelagic bacteria. mar. b i d . 52. 199-206. linley, e. a. s.. newell, r. c. & lucas. m. i . 1983: quan titative relationship between phytoplankton, bacteria and heterotrophic microflagellates in shelf waters. mar. ecol. prog. ser. 12. 77-89. lorenzen, c. j . 1967: determination of chlorophyll and phaeoigments: spectro-photometric equations. limnof. oce anogr. 12. 34s346. m ~ l l e r jensen, l. 1983: phytoplankton release of extracellular organic carbon molecular weight composition and bacterial assimilation. mar. ecol. prog. ser. 11. 39-48. mullins, b. w . a priddle, j . 1987: relationships between 45, 1622-1632. bacteria and phytoplankton in the bransfield strait and sou thern drake passage. br. a n f . suru. bull. 76. 51-64. parsons. t . r . & strickland, j . d. h. 1962: on the production of particulate organic carbon by heterotrophic proccsscs in seawater. deep-sea res. 8, 211-222. pomcroy. l. r . & deibel, d . 1986: temperature regulation of bacterial activity during the spring bloom in newfoundland coastal waters. science 233. 359-361. porter. k. g. & feigh, y. s. 1980: use of dapi for identifying and counting aquatic microflora. limnol. oceanogr. 25,94> 948. pomeroy, l. r . , macko, s. a,, ostrom. p. h . & dunphy, 1. 1990: the microbial food web in arctic seawater: con centration of dissolved free amino acids and bacterial abun dance and activity in the arctic ocean and in resolute passage. mar. ecol. prog. ser. 61. 31-40. riemann. b., bjernsen. p. k., newell. s. y. & fallon, r. d. 1987: calculation of bacterioplankton production from measurements of 'h-thymidine incorporation. limnol. oce anogr. 3 2 . 471-476. servais. p. 1986: etude de la dbgradation de la matiere organ ique par les bactiries hbtbrotrophes en riviere. divel oppement d'une demarche mithodologique et application a la meuse belge. universitk libre de bruxelles. faculti des sciences. thtse. 271 pp. servais, p.. billen, g . & vives-rego. j . 1985: rate of bacterial mortality in aquatic environments. appl. enuiron. microbiol. 49. 1448-1455. servais. p., billen, g. & hascoet, m. c . 1987: determination of the biodegradable fraction of dissolved organic matters in waters. wafer res. 21. 445-450. servais, p.. billen. g . . martinez, j . & vives-rego. j . 1989: estimating bacterial mortality by the dissapearance of 3h labelled intracellular dna. technical validation and field measurements. fems microbiol. ecology 62, 119-126. simon, m. & azam. f. 1989: protein content and protein synthesis rates of planktonic marine bacteria. mar. ecol. prog. ser. 51. 201-213. somville. m. 1984: measurement and study of substrate speci ficity of exoglucosidase activity in eutrophic water. appl. enuiron. microbiol. 48, 1181-1185. somville. m. & billen, g. 1983: a method for determining exoproteolytic activity in natural waters. limnol. oceanogr. 28. 190-193. sorokin, y. 1. 1971: on the r61e of bacteria in the productivity of tropical oceanic waters. int. reo. ges. hydrobiol. 56, 1 48. sullivan. c. w.. cota. g . f.. krempin. d. w. & smith. w. 0.. jr. 1990: distribution and activity of bacterioplankton in the marginal ice zone of the weddell-scotia sea during austral spring. mar. ecol. prog. ser. 63, 239-252. wolter, k. 1982: bacterial incorporation of organic substances released by natural phytoplankton populations. mar. ecol. prog. ser. 7 , 287-295. wright, r . t. & hobbie, j. e. 1965: the uptake of organic solutes in lake water. limnol. oceanogr. 10, 22-28. førland.indd 113førland & hanssen-bauer 2003: polar research 22(2), 113–124 a combination of instrumental records and reconstructions from proxy sources indicate that arctic air temperatures in the 20th century were the highest in the past 400 years (serreze et al. 2000). during the 20th century an increase in annual precipitation has been observed at higher northern latitudes (hulme 1995; dai et al. 1997). the norwegian arctic has experienced a substantial increase in precipitation during the 20th century, but although the temperature has increased during the latest decades there is no signifi cant long-term trend in annual temperatures (førland et al. 2002; hanssen-bauer 2002). global climate models project signifi cant increase of temperature and precipitation in high northern latitudes as greenhouse gas concentrations increase (ipcc 2001). the warming in high northern latitudes may be amplifi ed by feedbacks from changes in snow and sea ice extent and thawing of permafrost. the freshwater budget in the arctic has become an increasingly important consideration in the context of global climate change (walsh et al. 1998) as it may be linked to the intermittency of north atlantic deep water formation and the global thermohaline circulation, which is a major determinant of global climate (aagaard & carmack 1989; mysak et al. 1990). the arctic freshwater budget is driven by past and future climate variations in the norwegian arctic: overview and novel analyses eirik j. førland & inger hanssen-bauer sparse stations and serious measuring problems hamper analyses of climatic conditions in the arctic. this paper presents a discussion of measuring problems in the arctic and gives an overview of observed past and projected future climate variations in svalbard and jan mayen. novel analyses of temperature conditions during precipitation and trends in fractions of solid/liquid precipitation at the arctic weather stations are also outlined. analyses based on combined and homogenized series from the regular weather stations in the region indicate that the measured annual precipitation has increased by more than 2.5 % per decade since the measurements started in the beginning of the 20th century. the annual temperature has increased in svalbard and jan mayen during the latest decades, but the present level is still lower than in the 1930s. downscaled scenarios for svalbard airport indicate a further increase in temperature and precipitation. analyses based on observations of precipitation types at the regular weather stations demonstrate that the annual fraction of solid precipitation has decreased at all stations during the latest decades. the reduced fraction of solid precipitation implies that the undercatch of the precipitation gauges is reduced. consequently, part of the observed increase in the annual precipitation is fi ctitious and is due to a larger part of the “true” precipitation being caught by the gauges. with continued warming in the region, this virtual increase will be measured in addition to an eventual real increase. e. j. førland & i. hanssen-bauer, norwegian meteorological institute, box 43 blindern, no-0313 oslo, norway, e.forland@met.no. 114 past and future climate variations in the norwegian arctic river runoff, accumulation/ablation of glaciers and precipitation over the arctic ocean. the observed and projected increases in temperature and precipitation in svalbard and jan mayen (fig. 1) thus have broad implications for arctic and, perhaps, global climate and the monitoring of climatic trends in these regions is therefore also important in a global context. analyses of climatic trends in the arctic are hampered by the sparse station network and serious measuring problems. the large year-to-year variations imply that the climate signals have to be strong to be statistically signifi cant. although the scenarios indicate substantial climate changes in the arctic, it is not necessarily the case that the fi rst signifi cant “greenhouse signal” will be found in this region. real climatic trends may be masked or amplifi ed when analyses are based upon inhomogeneous series. studies have revealed that inhomogeneities in arctic climate series are often of the same magnitude as typical long-term trends (hanssen-bauer & førland 1994; nordli et al. 1996). for arctic stations in canada, mekis & hogg (1999) demonstrated that the precipitation trend was almost doubled after adjusting the series. accordingly, it is of crucial importance to adjust series for inhomogeneities when they are used in studies of long-term climate variations. the climate and long-term climatic variations at the norwegian arctic stations are described in a number of old and new publications, e.g. birkeland (1930), hesselberg & johannessen (1958), steffensen (1969, 1982), hisdal (1976), vinje (1982), hanssen-bauer et al. (1990), førland et al. (1997a) and winther et al. (2003). serreze et al. (2000) review observational evidence of recent changes in the arctic environment. in this paper a discussion of measuring problems in the arctic and an overview of past and future climate variations are given in the fi rst sections. in the last sections novel analyses of temperature conditions during precipitation and trends in fractions of solid/liquid precipitation at the arctic stations are outlined, and it is demonstrated that the observed trends in measured precipitation may deviate from the real precipitation trends. fig.1. location of current manual weather stations in the norwegian arctic. bjørnøya: elevation 16 m a.s.l., start of measurements 1920. hopen: 6 m a.s.l., 1944. hornsund (polish): 10 m a.s.l., 1978. sveagruva 9 m a.s.l., 1978. barentsburg (russian): 70 m a.s.l., 1933. svalbard airport: 28 m a.s.l., 1975. ny-ålesund: 8 m a.s.l., 1974. jan mayen: 10 m a.s.l., 1921. 115førland & hanssen-bauer 2003: polar research 22(2), 113–124 meteorological measuring problems in the arctic general measuring problems the arctic climate poses several serious challenges for the monitoring of the main weather elements. icing and wet snow may cause malfunctioning of the various sensors at the weather stations. during the polar night, the combination of darkness and harsh weather occasionally complicates manual observations. the combination of dry snow, high wind speed and open tundra increase dramatically the measuring errors for precipitation and snow depth at most stations in the norwegian arctic. because of blowing snow, the snow layer on the ground is likely to show large local variations (winther et al. 1998; winther et al. 2003), and the regular snow depth measurements at weather stations are therefore seldom representative for the snow accumulation in the station area. consequently, measurements of snow cover and snow depth have been given little priority at the norwegian arctic weather stations. errors in precipitation measurements several types of errors are connected to precipitation measurements (goodison et al. 1998). for the nordic countries, førland et al. (1996) concluded that the real amount of precipitation (“true precipitation”) might be expressed as: pc = k ⋅(pm + ∆pw + ∆pe ), (1) where pc is true precipitation, k is the correction factor due to aerodynamic effects, pm is measured precipitation, ∆pw is precipitation lost by wetting, and ∆pe is precipitation lost by evaporation from the gauge. other error types, such as splash in/ out, instrumental errors, misreadings etc., are either corrected in routine quality controls or may be neglected under nordic climate conditions. however, drifting or blowing snow occasionally cause substantial problems in the arctic. “precipitation” caused solely by blowing snow is excluded through the quality control at the norwegian meteorological institute, but there is often a combination of precipitation and blowing snow. in such cases it is diffi cult to distinguish the proportions of real precipitation and blowing snow. in the arctic, typical values of the combined effect of wetting and evaporation loss (∆pw + ∆pe) for the norwegian gauge is 0.10 0.15 mm/case for solid, liquid and mixed precipitation (førland & hanssen-bauer 2000). at most measuring sites, wind speed is the most important environmental factor contributing to the undercatch of the precipitation gauges. based on results from the world meteorological organization solid precipitation measurement intercomparison (goodison et al. 1998), nordic precipitation gauge studies (førland et al. 1996) and fi eld measurements in ny-ålesund, førland & hanssen-bauer (2000) deduced correction models for hourly and daily measurements in the norwegian precipitation gauge under arctic conditions. the correction factor for solid precipitation was found to increase with increasing wind speeds, and decrease with increasing temperature. by considering typical values of wind speed, temperature and precipitation intensity, førland & hanssen-bauer (2000) suggested the following rough correction factors for unsheltered stations on spitsbergen: liquid precipitation kl = 1.15, solid ks = 1.85 and mixed km = (0.5 * kl + 0.5 * ks) = 1.5. it should be stressed that using these typical correction factors does not necessarily produce accurate estimates of true precipitation at particular individual stations. further, the corrections do not refl ect differences in wind exposure between different measuring sites. adjustment for inhomogeneities inhomogeneities in climatic series may be caused by relocation of sensors, changed environment (such as new buildings) and instrumental improvements. to acquire reliable long-term climate series in the arctic is particularly complicated. because of the harsh weather conditions, even small changes at measuring sites may cause substantial changes in measuring conditions for precipitation, for example. identifi cation of inhomogeneities in arctic climate series is further hampered by the sparse station network. homogeneity tests based upon comparison with neighbouring stations are diffi cult to perform for bjørnøya (the southernmost island of svalbard) and jan mayen, for example, as the nearest neighbouring stations are more than 300 km away. a detailed survey of the results of the homogeneity analyses for norwegian arctic series is given by nordli et al. (1996). 116 past and future climate variations in the norwegian arctic temperature and precipitation variations in the 20th century climate series for the norwegian arctic the available climate data from the norwegian arctic is rather limited. the present network of synoptical weather stations consists of fi ve stations on spitsbergen and three stations on other arctic islands (fig. 1). the oldest meteorological observations from the norwegian arctic were made during scientifi c expeditions to svalbard and jan mayen. in 1911 a permanent weather station was established in green harbour, western spitsbergen. around 1920, weather stations were established at bjørnøya and jan mayen. long-term climate series for spitsbergen are established by joining series from different sites, and applying statistical methods (nordli et al. 1996). for svalbard airport the combined series is mainly based upon observations from green harbour/barentsburg and longyearbyen/ svalbard airport. the ny-ålesund series is based upon measurements from isfjord radio and nyålesund. the weather stations in ny-ålesund and svalbard airport were both moved to their present sites in 1975. the long-term temperature and precipitation series are adjusted before 1975 to be valid for the present sites. temperature there are pronounced fl uctuations in arctic climate on daily, monthly and annual time scales. the lowest recorded temperature at the norwegian arctic stations is –46.3 °c, but even during midwinter, temperatures well above zero have been recorded at all stations (e.g. +12.3 °c at jan mayen on december 2001). during summer, maximum temperatures above 20 °c have occasionally been recorded at bjørnøya and svalbard airport. there are no signifi cant trends in the annual temperature at svalbard airport, bjørnøya and jan mayen from the start of the series to the present (table 1). however, a closer examination of the series reveals three sub-periods with signifi cant trends. from the start in the 1910s there is a positive trend up to the late 1930s, a temperature decrease from the 1930s to the 1960s, and from the 1960s to the present the temperature has increased signifi cantly. figure 2 shows that despite the warming in the recent decades, the warmest two decades on an annual basis are still fig. 2. low-pass fi ltered series of annual temperature at norwegian arctic stations. the series are smoothed using gaussian weighting coeffi cients and show variations on a decadal time scale. (the last three years of the curves are omitted as fi ltered series are unreliable at the ends.) table 1. linear trends (°c per decade) in observed temperatures. statistical signifi cant trends (mann-kendall) are in boldface (5 % level) and underlined (1 % level). station 1912–2001 1910– 1945 1946– 1975 1976– 2001 bjørnøya (–0.01) (+0.08) –0.29 +0.49 hopen (+0.05) – –0.53 +0.84 sveagruva – – – +1.84 b svalbard airport a +0.15 +1.20 –0.48 +0.78 ny-ålesund a – – –0.40 +0.42 jan mayen (–0.08) (–0.20) –0.71 +0.49 northern hemisphere (land) +0.07 c +0.14 d –0.04 +0.31 e global (land) +0.06 c +0.11 d –0.01 +0.22 e a combined series before 1975 b 1979–2001 c 1901–2000 e 1976–2000 d 1901–1945 117førland & hanssen-bauer 2003: polar research 22(2), 113–124 the 1930s and the 1950s. an interesting feature is that the long-term series from the norwegian arctic stations show that on a decadal time scale, local temperature minima and maxima largely occur within the same decades for all seasons (førland et al. 1997a). because of substantial seasonal differences in standard deviations, the variation in annual mean temperatures is generally more affected by the variation in winter temperature than by summer temperatures. accordingly, both for the warming up to the 1930s and for the decrease in annual temperature from the 1930s to the 1960s, variations in winter temperatures were dominant. however, during the latest three decades, increased spring temperatures gave the largest single contribution to the increase in annual temperature. the temperature level at the norwegian arctic stations is currently somewhat lower than in the 1930s. this is contrary to the rest of northern europe and for the globe as a whole, where the present level is signifi cantly higher than the 1930s level (parker & alexander 2002). in table 1 temperature trends are given for the sub-periods applied in the latest intergovernmental panel on climate change report (folland & karl 2001). during 1946–1975, all stations experienced a negative trend of –0.3 to –0.7 °c/decade. for recent decades (1976–2001), the trend is positive at all stations, with the strongest warming at hopen, sveagruva and svalbard airport. despite the rather strong trends since 1976, the svalbard airport series is the only one with a statistically signifi cant trend at the 1 % level. hanssen-bauer & førland (1998a) found that though the temperature increase in the norwegian arctic during the latest decades to a large degree may be explained by changes in atmospheric circulation, this is apparently not the case with respect to the early 20th century warming. a model based on regional atmospheric circulation indices was able to account for most of the trend from the 1960s to the present, but only about one-third of the observed temperature increase at svalbard from 1912 to the 1930s and for the subsequent temperature decrease from the 1930s to the 1960s. fu et al. (1999) suggest that ocean circulation and sea surface temperatures may be important for explaining the warming in the northern north atlantic region before 1940; they conclude that this warming is not yet fully understood. precipitation the severe measuring problems discussed above create serious uncertainties in arctic precipitation values. precipitation in the arctic is low because air masses are usually stably stratifi ed and contain only small amounts of water vapour. the normal (1961–1990) annual precipitation at svalbard airport (190 mm) is the lowest at any norwegian station. there are large local gradients in precipitation between the spitsbergen stations: although the distance is just 35 km, the annual precipitation at barentsburg is almost three times as high as at svalbard airport. by measuring several transects, sand et al. (2003) revealed both west–east and south–north gradients of snow accumulation on spitsbergen. they found that the winter accumulation rates along the east coast were about 40 % higher than on the west coast, and that the southern part of the island receives about twice as much winter precipitation as the northern part. large local precipitation gradients were also found for the ny-ålesund area (førland et al. 1997b). the precipitation distribution was found to be strongly dependant on the large-scale wind direction. with winds from the south and south-west, the precipitation at a glacier (brøggerbreen) a few kilometres southwest of ny-ålesund was about 60 % higher than in ny-ålesund, while with winds from the northwest ny-ålesund received more precipitation than the glacier. annual precipitation (fig. 3) has increased substantially during the 20th century at most of the stations in the norwegian arctic. both at svalbard airport and bjørnøya the increase is larger than 2.5 % per decade (table 2). at jan mayen most of the increase happened before 1960, while the increase at the other stations is more evenly distributed throughout the 20th century. the course of the precipitation increase at svalbard parallels the increase in coastal parts of northern norway (hanssen-bauer & førland 1998b), with a trend that seems to be fairly constant throughout the 20th century. however, the relative precipitation increase on spitsbergen and bjørnøya is considerably higher than the concurrent increases on the norwegian mainland. it is also higher than the “average high latitude increase” estimated by hulme (1995). the observed long-term variations in precipitation on the west coast of spitsbergen during the 20th century may be explained largely by varia118 past and future climate variations in the norwegian arctic tions in the average atmospheric circulation conditions (hanssen-bauer & førland 1998a). hanssen-bauer (2002) concluded that about 70 % of the trend in annual precipitation at svalbard airport during the period 1912–1997 was accounted for by variations in atmospheric circulation. future climate development scenarios of temperature and precipitation for svalbard for the next 50 years have been worked out by hanssen-bauer (2002) by empirical downscaling of an integration with the max-planck institute’s coupled atmosphere–ocean global climate model echam4/opyc3. the integration (gsdio) has a physical parameterization which accounts for direct and indirect effects of sulphur aerosols in addition to greenhouse gases, including tropospheric ozone (roeckner et al. 1999), and is based upon the emission scenario is92a (houghton et al. 1992). the trend in the downscaled temperatures from the gsdio integration for the period 1960– 2000 is mainly in accordance with what has been observed during that period, while the projected annual warming rate up to 2050 is almost fi ve times greater than that observed for the last 90 years (table 3). a similar warming rate is projected in this area by dynamical downscaling based upon the same climate model (bjørge et al. 2000). the projected warming is statistically signifi cant at the 1 % level in all seasons. hanssen-bauer & førland (2001) concluded that less than 20 % of the warming projected by the gsdio integration in svalbard could be accounted for by changes in the atmospheric circulation. when compared to the warming during recent decades, this implies that a diminishing part of the projected warming will be attributed to changes in circulation. some of the warming is probably directly connected to the greenhouse warming. however, the gsdio integration shows extensive melting of sea ice east of svalbard, and feedback effects from the melting probably contribute signifi cantly to the strong warming in the area (bjørge et al. 2000). benestad et al. (2002) compared downscaled temperature scenarios for svalbard based upon three different global climate models. they concluded that differences between the models concerning sea ice conditions lead to highly variable local temperature projections in svalbard. the realism of future temperature scenarios is therefore critically dependent on table 2. linear trends (% per decade) in observed and projected annual and seasonal precipitation. statistical signifi cant trends (mann-kendall) are in boldface (5 % level) and underlined (1 % level). the magnitude of the trend is relative to the (observed) 1961–1990 normal. station period annual winter spring summer autumn bjørnøya 1920–2001 +2.8 +3.9 +4.8 +1.3 +2.1 jan mayen 1921–2001 +1.7 +2.5 +4.6 +1.9 –0.6 svalbard airport (observed) 1912–2001 +2.7 –0.2 +2.2 +4.9 +3.7 svalbard airport (projected) 1961–2050 +1.4 +1.7 +4.6 -0.9 +0.6 fig. 3. low-pass fi ltered series of measured annual precipitation at norwegian arctic stations. the series are smoothed using gaussian weighting coeffi cients and show variations on a decadal time scale. (the last three years of the curves are omitted as fi ltered series are unreliable at the ends.) 119førland & hanssen-bauer 2003: polar research 22(2), 113–124 the reliability of the projected changes in the sea ice concentrations in the region. the downscaled precipitation scenario (hanssen-bauer 2002) also indicates that annual precipitation will increase signifi cantly up to 2050, mainly because of a highly signifi cant projected increase in spring precipitation (table 2, bottom row). dynamical downscaling (bjørge et al. 2000) projects an even higher precipitation increase (ca. 2 % per decade) at the west coast of spitsbergen. analyses of the svalbard airport series indicate that precipitation variation to a larger degree than temperature variation may be explained by changes in the atmospheric circulation. this is at least partly due to the local topography, which shelters against precipitation from some sectors while it orographically enhances the precipitation from other sectors. this is also valid for the climate scenario, but the infl uence of atmospheric circulation on the long-term trend in the scenario is considerably smaller than it has been during the 20th century. a major part of the projected precipitation trend is accounted for by the temperature increase, which is used in the empirical downscaling models as a proxy for increased air humidity. as different climate models seem to show a closer agreement concerning the temperature signal than concerning changes in atmospheric circulation (räisänen 2001), this part of the trend is probably also more credible than the part caused by variations in the atmospheric circulation. precipitation characteristics frequencies of different precipitation types the frequency of precipitation events is substantially higher at the island stations bjørnøya and jan mayen than at the spitsbergen stations svalbard airport and ny-ålesund (table 4). based on four observations per day (00, 06, 12 and 18 utc), the average number of events at jan mayen implies that there is precipitation about 31 % of the time. the value for svalbard airport is 20 %. snow is the most frequent precipitation type. at svalbard airport, for example, around 75 % of precipitation events are reported as snow. at all stations, 15 20 % of precipitation events are reported as rain and about 5 % as sleet. drizzle constitutes 20 % of precipitation events at jan mayen but just 4 % at svalbard airport. air temperature during precipitation at svalbard airport, 35 % of snow events are reported at air temperatures below –10 °c; at jan mayen the value is 13 % (fig. 4a). at all stations less than 10 % of snow events are observed at temperatures above 0 °c. at svalbard airport, 30 % of the cases with sleet are reported for temperatures > + 2°c; at bjørnøya just 5 % (fig. 4b). for rain (fig. 4c), around 25 % of the events at svalbard airport are reported at temperatures lower than 3 °c; at bjørnøya the percentage is above 50 %. the geographical differences in temperature distribution are smaller for drizzle (fig. 4d) than for rain. at svalbard airport and nyålesund, ca. 30 % of drizzle events are reported at temperatures below +3 °c; at jan mayen and bjørnøya around 40 %. wildlife, particularly the reindeer on spitsbergen, are vulnerable to events with snow crust or icy conditions. extensive starving and death table 3. linear trends (°c per decade) in observed and projected annual and seasonal temperature at svalbard airport. statistical signifi cant trends (mann-kendall) are underlined (1 % level). (from hanssen-bauer 2002.) annual winter spring summer autumn observed (1912–2000) +0.14 +0.04 +0.37 +0.04 +0.11 projected (1961–2050) +0.61 +0.99 +0.52 +0.29 +0.62 table 4. frequencies of various precipitation types. the frequencies are given as percentage of the total number of cases based on 4 observations per day (at 00, 06, 12 and 18 utc). however, at ny-ålesund there are no observations at 00 utc and the number of cases is adjusted to 4 per day. bjørnøya svalbard airport nyålesund jan mayen no. of cases per year 365.2 289.0 295.6 455.9 drizzle (%) 16.5 3.9 8.6 20.1 rain (%) 19.9 16.5 17.0 19.5 sleet (%) 5.5 4.0 5.8 5.2 snow (%) 55.3 73.6 65.2 51.8 freezing rain/ drizzle (%) 0.4 0.3 0.2 1.0 hail, snow crystals (%) 2.4 1.8 3.2 2.4 120 past and future climate variations in the norwegian arctic of reindeer was reported after severe crust and ground ice formation in november and december 1993. table 5 shows that episodes with rain or drizzle falling at temperatures below 0 °c are rather infrequent at spitsbergen; it occurs on average just once a year in longyearbyen, svalbard airport and ny-ålesund. at jan mayen it is more frequent, with nearly 10 cases per year. the low frequencies of freezing rain/drizzle at spitsbergen taken into consideration, it seems that it is rather seldom that events with comprehensive snow crust or ice formation are caused by liquid precipitation at temperatures below zero. other causes include melting and refreezing at the snow surface, or rain absorbed and subsequently frozen in the surface snow layer. fractions of snow and rain as a function of air temperature figure 5 demonstrates that there are distinct geographical differences in fractions of liquid/ solid precipitation as a function of air temperature. for near zero temperatures on bjørnøya and jan mayen, the fraction of liquid precipitation is generally higher than at the spitsbergen stations. on bjørnøya, the precipitation is liquid in 90 % of precipitation events when the temperature is above 1.5 °c, while in longyearbyen, svalbard fig. 4. cumulative distribution of air temperature during precipitation as (a) snow, (b) sleet, (c, opposite page) rain and (d, opposite page) drizzle. (a) (b) table 5. threshold temperature for equal probability of solid and liquid precipitation, and number of events (4 observations/day) per year with liquid precipitation observed for t < 0 °c. station name period threshold temp. (°c ) events/yr bjørnøya 1956–1999 0.84 3.0 svalbard airport 1975–1999 1.70 1.1 longyearbyen 1957–1977 1.96 1.0 ny-ålesund 1975–1999 1.62 1.0 jan mayen 1956–1999 1.03 8.5 121førland & hanssen-bauer 2003: polar research 22(2), 113–124 airport and ny-ålesund this threshold is reached at around 3 °c. the “threshold” temperature—where the probability for liquid and solid precipitation is equal— differs at the individual arctic stations (table 5). at the stations on bjørnøya and jan mayen, this threshold temperature is below or close to 1.0 °c, while at the spitsbergen sites it is higher than 1.5 °c. the same pattern is also found for sleet (fig. 4b), where the median temperature is lower on bjørnøya and jan mayen than at the spits bergen stations. this indicates that, at the same 2 m air temperature, the air mass aloft during precipitation is colder over spitsbergen than over bjørnøya and jan mayen. bearing in mind that rain or snow in this region may occur throughout the year, two possible reasons for this apparently more stably stratifi ed air over the island stations during precipitation might be: (1) the contribution from convective precipitation over spitsbergen caused by solar heating of the ground during summer; (2) during most of the year, bjørnøya and jan mayen are farther from the sea ice border than the spitsbergen stations, and cold air masses from sea ice covered areas are better mixed because of the longer travel distance over open sea. trends in annual amounts of solid and liquid precipitation at hopen and svea, ca. 60 % of the annual precipitation amount during the period 1975–2001 was reported as snow, and only about 20 % as rain. at svalbard airport and ny-ålesund, the fi gures were ca. 45 and 25 %, while ca. 25 % fell as sleet or a mixture of rain and snow. on bjørnøya and jan mayen, the amounts of snow, rain and mixed precipitation were nearly equal. these fractions are based on semi-daily measurements of precipitation amounts and the precipitation types report(c) (d) 122 past and future climate variations in the norwegian arctic ed by the observers. no correction for gauge undercatch has been performed and, accordingly, the fraction of solid precipitation is underestimated. the fractions of solid precipitation have diminished at all stations during the latest decades, particularly at svalbard airport and jan mayen. based on linear regression, the fraction of solid precipitation on jan mayen is reduced from 39 % in 1975 to 20 % in 2001. the fraction of annual precipitation reported as mixed precipitation (i.e. sleet, or a combination of rain and snow during the 12h sampling interval) has increased at all stations. fictitious trends in precipitation amounts precipitation records from the arctic are infl uenced by substantial measuring errors, e.g. caused by undercatch of conventional precipitation gauges. as the gauge undercatch is different for snow and rain, and further depends on wind and temperature, changes in climate will result in changes in the undercatch of the gauges. reduced fractions of annual precipitation falling as snow lead to a reduced annual gauge undercatch, and thus a fi ctitious positive trend for precipitation even if the true precipitation does not change at all (førland & hanssen-bauer 2000). the potential for such artifi cial trends is maximum in areas with strong winds and where a large percentage of the annual precipitation is solid, for example, in the norwegian arctic. by applying the rough correction factors presented earlier on the annual amounts of solid, liquid and mixed precipitation it is possible to give crude estimates of “true” precipitation (pc). in table 6, the same correction factors for solid, liquid and mixed precipitation have been applied to all the arctic stations, with no consideration taken to differences in wind and temperature conditions at the stations. the measured values fig. 5. fractions of observations classifi ed as liquid precipitation at different temperatures (ra and sn are amounts of precipitation as rain and snow, respectively). table 6. changes in precipitation, 1975–2001. pm is mean measured annual precipitation. mean correction factor is the ratio between corrected (pc) and measured (pm) precipitation. change is the difference between levels in 1975 and 2001, based on linear regression. change for measured and corrected precipitation is given both in millimetres and as a percentage per decade of the 1975 level. precipitation change pm (mm) mean correction factor pc (mm) measured corrected change (mm) change (%) change (mm) change (%) bjørnøya 396 1.52 602 129 15.0 198 15.2 hopen 469 1.64 767 –65 –5.0 –119 –5.6 sveagruva 271 1.66 451 –40 –5.2 –100 –7.6 svalbard airport 192 1.56 299 10 2.1 5 0.7 ny-ålesund 403 1.56 631 88 9.4 142 9.8 jan mayen 680 1.48 1007 –97 –5.2 –203 –7.2 123førland & hanssen-bauer 2003: polar research 22(2), 113–124 are not corrected for evaporation and wetting effects. the rough estimates of pc presented in table 6 indicate that the true precipitation at all stations in the svalbard region is more than 50 % higher than the measured values. the estimates in table 6 are based on a short time period and rather crude approximations, but nonetheless illustrate the importance of correcting arctic precipitation series for undercatch. for most stations there are substantial differences between trends based on measured and corrected values, both in material amounts and also for relative changes. for instance, the increase in measured annual precipitation at svalbard airport during the period 1975–2001 is 2.1 % per decade. however, by correcting for gauge undercatch, the increase in the resulting estimates for “true” precipitation is 0.7 % per decade. the scenarios currently available (table 3) indicate a 3 °c increase in annual temperature from the present to 2050 in svalbard. for an increase in annual temperature of 4 °c, førland & hanssen-bauer (2000) estimated a fi ctitious precipitation increase of 2 % per decade. this virtual increase, which is caused solely by reduced measuring errors, is thus of the same magnitude as the projected precipitation increase of 1.4 % per decade (table 2) under global warming. this virtual increase will be measured in addition to an eventual real increase. conclusions annual temperatures in the longyearbyen/svalbard airport area have increased by more than 1 °c since 1910, but because of large interannual and decadal variations this trend is not statistically signifi cant. although the temperature has increased signifi cantly since the cold 1960s, the present temperature level is still lower than in the 1930s at all stations in the norwegian arctic. measured annual precipitation in the svalbard region and at jan mayen has increased substantially (15 25 %) during the last 80 to 90 years. at bjørnøya, svalbard airport and jan mayen, the positive precipitation trend during the 20th century is statistically signifi cant. the fraction of annual precipitation falling as snow has decreased at all stations in the norwegian arctic during recent decades. this leads to a reduced annual undercatch in the precipitation gauges, and consequently a fi ctitious positive trend in measured precipitation. there are substantial differences between measured and “true” precipitation in the arctic, both with respect to material amounts as well as trends. accordingly, corrected precipitation values should be used in studies of historical trends as well as for monitoring future trends. estimates of “true” precipitation are also important for water balance assessments in the arctic. acknowledgements.—thanks to jan-gunnar winther at the norwegian polar institute for useful suggestions, and to two anonymous reviewers who contributed to the improvement of the manuscript. references aagaard, k. & carmack, e. c. 1989: the role of sea ice and other fresh waters in the arctic circulation. j. geophys. res. 94(c10), 1485–1498. benestad, r., førland, e. j. & hanssen-bauer, i. 2002: empirically downscaled temperature scenarios for svalbard. atmos. sci. lett., doi:10.1006/asle.2002.0051. birkeland, b. j. 1930: temperaturvariationen auf spitzbergen. (temperature variations on spitsbergen.) meteorol. z. 47, 234–236. bjørge, d., haugen, j. e. & nordeng, t. e. 2000: future climate in norway. dynamical experiments within the regclim project. res. rep. 103. oslo: norwegian meteorological institute. dai, a., fung, i. y. & del genio, a. d. 1997: surface observed land precipitation variations during 1900–88. j. clim. 10, 2943–2962. folland, c. & karl, t. r. 2001: observed climate variability and change. in international panel on climate change: climate change 2001: the scientifi c basis. contribution of working group i to the third assessment report of the intergovernmental panel on climate change. pp. 99–181. cambridge: cambridge university press. førland, e. j., allerup, p., dahlström, b., elomaa, e., jónsson, t., madsen, h., perälä, j., rissanen, p., vedin, h. & vejen, f. 1996: manual for operational correction of nordic precipitation data. klima 24/96. oslo: norwegian meteorological institute. førland, e. j. & hanssen-bauer, i. 2000: increased precipitation in the norwegian arctic: true or false? clim. change 46, 485–509. førland, e. j., hanssen-bauer, i. jónsson, t., kern-hansen, c., nordli, p. ø., tveito, o. e. & vaarby laursen, e. 2002: twentieth century variations in temperature and precipitation in the nordic arctic. polar rec. 38, 203–210. førland, e. j., hanssen-bauer, i. & nordli, p. ø. 1997a: climate statistics and long-term series of temperature and precipitation at svalbard and jan mayen. klima 21/97. oslo: norwegian meteorological institute. førland, e. j., hanssen-bauer, i. & nordli, p. ø. 1997b: orographic precipitation at the glacier austre brøggerbreen, svalbard. klima 02/97. oslo: norwegian meteorological 124 past and future climate variations in the norwegian arctic insti tute. fu, c., diaz, h. f., dong, d. & fletcher, o. 1999: changes in atmospheric circulation over the northern hemisphere oceans associated with the rapid warming of the 1920s. int. j. climatol. 19, 581–606. goodison, b. e., louie, p. y. t. & yang, d. 1998: wmo solid precipitation measurement intercomparison. wmo/tdrep. 872. geneva: world meteorological organization. hanssen-bauer, i. 2002: temperature and precipitation in svalbard 1912–2050: measurements and scenarios. polar rec. 38, 225–232. hanssen-bauer, i & førland, e. j. 1994: homogenizing long norwegian precipitation series. j. clim. 7, 1001–1013. hanssen-bauer, i. & førland, e. j. 1998a: long-term trends in precipitation and temperature in the norwegian arctic: can they be explained by changes in the atmospheric circulation patterns? clim. res. 10, 143–153. hanssen-bauer, i. & førland, e. j. 1998b: annual and seasonal precipitation variations in norway 1896–1997. klima 27/98. oslo: norwegian meteorological institute. hanssen-bauer, i. & førland, e. j. 2001: verifi cation and analysis of a climate simulation of temperature and pressure fi elds over norway and svalbard. clim. res. 16, 225– 235. hanssen-bauer, i., solås, m. k. & steffensen, e. l. 1990: the climate of spitsbergen. klima 39/90. oslo: norwegian meteorological institute. hesselberg, t. & johannessen, t. w. 1958: the recent variations of the climate at the norwegian arctic stations. in r. c. sutcliffe (ed): polar atmosphere symposium, part i, meteorological section, oslo, norway, 2–8 july, 1956, pp. 18–29. london: pergamon press. hisdal, v. 1976: geography of svalbard. a short survey. tromsø: norwegian polar institute. houghton j. t., callander, b. a. & varney, s. k. 1992: climate change 1992. cambridge: university press. hulme, m. 1995: estimating global changes in precipitation. weather 50, 34–42. ipcc (international panel on climate change) 2001: climate change 2001: the scientifi c basis. contribution of working group i to the third assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. mekis, e. & hogg, w. d. 1999: rehabilitation and analysis of canadian daily precipitation time series. atmos.–ocean 37, 53–85. mysak, l., manak d. k. & marsden, r. f. 1990: sea ice anomalies observed in the greenland and labrador seas during 1901–1984 and their relation to an interdecadal climate cycle. clim. dyn. 5, 111–133. nordli, p. ø., hanssen-bauer, i. & førland, e. j. 1996: homogeneity analyses of temperature and precipitation series from svalbard and jan mayen. klima 16/96. oslo: norwegian meteorological institute. parker, d. e. & alexander, l. 2002: global and regional climate in 2001. weather 57, 328–340. räisänen, j. 2001: co2 induced climate change in cmip2 experiments: quantifi cation of agreement and role of internal variability. j. clim. 14, 2088–2104. roeckner, e., bengtsson, l., feichter, j., lelieveld, j. & rodhe, h. 1999: transient climate change simulations with a coupled atmosphere–ocean gcm including the tropospheric sulphur cycle. j. clim. 12, 3004–3032. sand, k., winther, j.-g., maréchal, d., bruland, o. & melvold, k. 2003: reginal variations of snow accumulation on spitsbergen, svalbard, 1997–99. nord. hydrol. 34, 17–32. serreze, m. c., walsh, j. e., chapin iii, f. s., osterkamp, t., dyurgerov, m., romanovsky, v., oechel, w. c., morison, j., zhang, t. & barry, r. g. 2000: observational evidence of recent change in the northern high-latitude environment. clim. change 46, 159–207. steffensen, e. 1969: the climate and its recent variations at the norwegian arctic stations. meteorol. ann 5, 217–349. steffensen, e. 1982: the climate at norwegian arctic stations. klima 5, 3–44. oslo: norwegian meteorological insti tute. vinje, t. 1982: frequency distribution of sea ice in the greenland and barents seas, 1971–80. nor. polarinst. årb. 1980, 57–61. walsh, j. e., kattsov, v., portis, d. & meleshko, v. 1998: arctic precipitation and evaporation: model results and observational estimates. j. clim. 11, 72–87. winther, j.-g., bruland, o., sand, k., killingtveit, å. & marechal, d. 1998: snow accumulation distribution on spitsbergen, svalbard, in 1997. polar res. 17, 155–164. winther, j-g., bruland, o., sand, k., gerland, s., marechal, d., ivanov, b., głowacki, p. & könig, m. 2003: snow research in svalbard. polar res. 22, 125–144 (this issue). << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /all /binding /left /calgrayprofile (dot gain 20%) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages true /colorimagedownsampletype /bicubic /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages true /grayimagedownsampletype /bicubic /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /fra <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> /enu (use these settings to create pdf documents with higher image resolution for improved printing quality. the pdf documents can be opened with acrobat and reader 5.0 and later.) /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308000200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e30593002537052376642306e753b8cea3092670059279650306b4fdd306430533068304c3067304d307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e30593002> /deu <feff00560065007200770065006e00640065006e0020005300690065002000640069006500730065002000450069006e007300740065006c006c0075006e00670065006e0020007a0075006d002000450072007300740065006c006c0065006e00200076006f006e0020005000440046002d0044006f006b0075006d0065006e00740065006e0020006d00690074002000650069006e006500720020006800f60068006500720065006e002000420069006c0064006100750066006c00f600730075006e0067002c00200075006d002000650069006e0065002000760065007200620065007300730065007200740065002000420069006c0064007100750061006c0069007400e400740020007a0075002000650072007a00690065006c0065006e002e00200044006900650020005000440046002d0044006f006b0075006d0065006e007400650020006b00f6006e006e0065006e0020006d006900740020004100630072006f0062006100740020006f0064006500720020006d00690074002000640065006d002000520065006100640065007200200035002e003000200075006e00640020006800f600680065007200200067006500f600660066006e00650074002000770065007200640065006e002e> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <feff0041006e007600e4006e00640020006400650020006800e4007200200069006e0073007400e4006c006c006e0069006e006700610072006e00610020006e00e40072002000640075002000760069006c006c00200073006b0061007000610020005000440046002d0064006f006b0075006d0065006e00740020006d006500640020006800f6006700720065002000620069006c0064007500700070006c00f60073006e0069006e00670020006f006300680020006400e40072006d006500640020006600e50020006200e400740074007200650020007500740073006b00720069006600740073006b00760061006c0069007400650074002e0020005000440046002d0064006f006b0075006d0065006e00740065006e0020006b0061006e002000f600700070006e006100730020006d006500640020004100630072006f0062006100740020006f00630068002000520065006100640065007200200035002e003000200065006c006c00650072002000730065006e006100720065002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice radiation climate variability in svalbard: surface and satellite observations jon bgrre b r b ~ k , vidar hisdal & lars edin svaasand this paper performs a climatological investigation of the surface radiation budget (srb) in svalbard. on the basis of the norwegian polar institute’s radiation measurements from ny-alesund ( 198 1-1 997) and the nasa/langley surface radiation budget dataset (1983-1991). the radiation climate is related to meteorological conditions and surface properties, and compared to surface radiation fluxes measured from space. the natural variability of the short-wave and long-wave radiation fluxes in ny-alesund is generally governed by the large annual variation i n the incoming light with polar night and polar day conditions, the large changes of surface albedo especially during spring and the atmospheric circulation with frequent cyclone passages during winter with alternating periods of warm, humid maritime air from the south and cold, dry arctic air from the north. comparison with the satellite derived s u r f x e radiation fluxes shows that ny h e s u n d is to a large extent influenced by the “ocean” climate to the west of svalbard during the summer and autumn, but has a more “continental” radiation climate rfpresentative of the more central parts of the island during winter and spring. n y alesund is located in a fiord on the north-west coast of svalbard, where the ocean cloud cover and the arctic sea fog play an important role during the summer. during the winter and spring. however, the fiords are frozen and the drift ice covers a large extent of the surrounding ocean. j. b . 0 r b a k . v . hisdal & l. e. svaasand. norwegian polar institute, polar etivirontnental centre, n-9296 tromji. norwuy. introduction the surface radiation budget and feedback mech anisms connected to cloud radiation and surface albedo are of major importance for the arctic climate and energy balance. as a probable result of increasing concentrations of greenhouse gases in the atmosphere, the global mean surface tempera ture has slowly risen by 0.6“c since the late 19th century (nicholls e t al. 1996). while the regional effects of this temperature rise on precipitation patterns, winds, cloud cover, etc. are difficult to describe, most global circulation models show a poleward amplification of the climate signals. as a result of the intensified temperature gradients in the atmosphere, a warming climate is therefore expected to give early and large effects in the polar areas. and. with a significant increase i n climate variability with more extreme weather situations, deeper cyclones, stronger seasonal cycles and increased precipitation. no significant trend in surface temperature is found in svalbard, but the precipitation has increased by as much as 25% since the beginning of this century (forland et al. 1997). the negative annual radiation budget of the arctic is balanced by the poleward transport of warm water and humid air from the atlantic ocean. according to orvig (1970), an average of 4-8 cyclones/month are found passing over the norwegian and barents seas. the european arctic is therefore potentially sensitive to climate pertur bations. this study describes some fundamental features of the natural variability of the ragiation climate of svalbard and, particularly, ny-alesund. because the arctic is sensitive to climate perturbations, identification of the basic features and natural variability of the radiation climate is therefore brbaek et al. 1999: polar research 18(2j, 13-7-133 127 total net radiation and total net cloud forcing, surface albedo and cloud amount. surface fluxes are derived from the international satellite cloud climatology project (isccp) data. radiation schemes developed at larc and top of atmos phere (toa) clear sky albedos from the earth radiation budget experiment (erbe) satellites (whitlock et al. 1993, 1995). figure 1 shows a map of svalbard and the location of isccp 280 x 280 km grid points used ia the analysis, as well as the location of ny alesund. the five selected grid points effectively divide svalbard into five climate zones comprising the central glaciated mainland (including the seasonally ice-covered fiords) and the ocean areas to the south, west, east and north of the islands. the five different zones with gridpoints are ocean area south at 76.25n, 15.86e (south), ocean area west at 78.75n, 06.43e (west), central mainland at 78.75n, 19.28e (cm), ocean area east at 78.75n, 32.14e (east) and ocean area fig. 1. map of svalbard with the location of isccp grid points used in the analysis, as well as the location of ny-alesund. only five grid-points are selected, dividing svalbard into five different climate zones representing the central glaciated mainland (including the seasonally ice-covered fiords) and the ocean areas to the south, west. east and north of spitsbergen. forth at 81.25n7 24.54e (north), as alesund (78.92n, i 1.83e). as ny surface radiation budget and climate important as a basis for further studies and long term monitoring. i t is also important to, know to what extent the radiation climate i n ny-alesund is representative of other parts of svalbard. the norwegian polar institute has collected measure ments of the surface oradiation budget on a permanent basis in ny-alesund since 1974, with the main objective of investigating the longand short-term variability of the arctic radiation climate as related to other parameters, such as seasonal snow cover, atmospheric variability and meteorological conditions. the programme in cludes solar radiation measurements of global, diffuse, direct, reflected, uv and uv-b short wave (sw) radiation, long-wave (lw) downward and lw upward radiation, as well as derived quantities like sw net, lw net, net radiation and surface albedo (vinje 1976-1980; hisdal et al. 1992; hisdal & finnekisa 1996). the nasalangley (larc) 8-year surface radiation budget (srb) data set contains monthly averaged srb parameters from july 1983 to june 199 1. the parameters are sw and lw downward radiation for all sky and clear sky conditions, net sw and lw radiation. sw and lw cloud forcing, meteorological conditions: the main features affecting the climate of svalbard are the general atmospheric circulation, the annual variation in light conditions and the arctic sea ice and ocean currents. a general description of the climate of svalbard has been given by hanssen-bauer et al. ( 1990) and forland et al. ( 1997). the general large-scale circulation is governed by the iceland low and the high pressure systems over greenland and the arctic ocean, forcing warm and humid air from the north atlantic ocean along the cyclone tracks to the norwegian and barents seas. the large difference i n air temperature between air masses of arctic or atlantic origin cause a large fluctuation in weather conditions, especially during winter. the northern part of the norwegian current, the west spitsbergen current, causes ice-free condi tion along the west coast during the whole year, as well as partially ice-free waters north of svalbard even during winter. according to the frequency distribution of sea ice charts (vinje 1982), the sea ice is much more dominant on the eastern side, with large annual variation. in winter the sea ice may reach down to bjornaya (74.50n, 19.00e) 128 radiation climate variability in svalbard nasa larc sre 76.25n, 15.881 south nasa larc sre 78.75n, 32.141 east la1 1"" m o n h ~~1 nasa lbrc srb 78.751,06.438 west -1 t +--/1 i w0"ui ,cl nasa larc sre 78.75n, 19.281 cm 1 3w- -total net -cloud "xr sw n e t all sky lw clear sky lw net all sky +lw all sky month sw net ni sky +lw all sky l w net all sky --albedo (a1 nasa larc sre 81.25n. 24.54e ~ north wo 500 sw clear sk +sw all sky sw net all sky i a i w lw net all sky ~ t o l d net -cloud % lw clear sky +lw ni sky p o ~.i month npin~a srb 78.92~. 1 1 . ~ 3 ~ ny-alesund 10 ka i i ~ l l a i i o n nyaa -sw netniaa -lw nei nvaa -rm ' -(oo ~ . ~ ~ . i 1 month month f i g . 2. mean surface radiation budget fluxes at svalbard 1983-1991: nasa langley srb data set for five different zone$: (a) south: (b) west: ( c ) central mainland : (d) east: and (e) north: as well as (0 the norwegian polar institute ny-alesund srb data bet of mean radiation quantities. the plots include the following pimmeters: short-wave (sw) clear sky, all sky and net all sky radiation. long-wave (lw) clear sky. all sky and net all sky nidiation. alhedo, total net radiation and cloud cover. for ny-alesund the sw top of the atmosphere radiation replaces the clear sky values. and the cloud cover data are based on manual observations. along the cold southward ocean current i n that area, whereas it retreats almost completely during summer. forland et al. (1997) include four stations on the svalbard mainland (longyearbyp lufthavn, isfjord radio, sveagruva and ny-alesund) and three ocean/island stations (hopen, bjarnaya and jan mayen) in their analysis. the results show that the number of days with overcast sky as well as the frequency of arctic sea fog is highest during summer at all stations, and highest at the ocean/ island stations. the number of clear days i n ny alesund is 5-8 daydmonth during the winter months and only 1 day/month during the summer months june to september, with a sharp transition occurring from may to june. forland et al. (1997) also showed that the characteristic winter air temperatures at svalbard are relatively high with large fluctuations. the fluctuations are lowest for the oceadisland stations like hopen and b j ~ r n a y a and largest for the stations on the mainland. longyearbyen and svea have the most continental climate with winter temperatures 2-5°c lower and summer tempera tures 1-2°c higher thap the coastal station at isfjord radio. for ny-alesund, the winter tem brbaek et al. 1999: polar reseurch ln(2). 127-134 129 peratures are similar to longyearbyen, whereas the summer temperatures are more like isfjord radio. this situabion, with a more continental climate for ny-alesund during winter and a coastal climate during summer is explained by its location in a fiord on the north-west coast of svalbard, which is frozen during winter but open and strongly influenced by the ocean during summer (forland et al. 1997). sutellite radiation fluxes: the srb parameters of the nasa/larc data set are given on the (isccp) 280 x 280 km grid, using only five grid points to be analysed for the svalbard region. the satellite srb fluxes from the five different zones south, west, cm, east and north are plotted in fig. 2a-e. in atdition the mean radiation quantities from ny-alesund are plotted in fig. 2f for the same period of time (1983-1991). the short-wave (sw) downward radiation fluxes range up to a summer maximum of approximately 200 w/m2 for the ocean areas south and west of svalbard as well as ny alesund, whereas the ocean areas east and north and the central mainland have sw maxima of about 280 wlm’. the surface albedo is always low for the ocean areas south and west and show intermediate averaged albedo values for the east and north. this is reflected by the frequency distribution of sea-ice concentration in the areas (vinje 1982). the ocean areas south and west are almost always ice-free, whereas the east and north are partially ice-covered throughout the seasons, with ice-free conditions during summer and autumn. however, whereas the polynya north of svalbard is partially ice-covered throughout the winter, the ocean to the east is totally ice-covered. the gridded albedo of the central mainland is representative of the spatial averaged high albedo glacier surfaces and the seasonally ice-covered fiords, giving intermediate and less variable satellite albedo values. the asymmetry of the sw fluxes with respect to the top of atmosphere (toa) insolation, and the net sw fluxes with respect to the s w fluxes, are induced by the seasonal variation in surface albedo. multiple reflection and scattering of the s w radiation between the surface and the atmos phere enhance the s w fluxes ovet high albedo surfaces. this is pronounced in ny-alesund as the snow melts during mayljune as well as in the ocean areas north and east when the ice cover withdraws northwards in late spring. the satellite derived lw downward radiation fluxes of fig. 2a-f show less variation over the year with similar summer values of about 300 wi m2 for all zones. however, the winter fluxes are larger (about 250 w/m2) over the two open ocean areas (south and west) as fompared to the iceand snow-covered areas (ny-alesund, cm, north and east), which show winter lw downward fluxes on the order of 200 w/m2. this means that variation in l w downward radiation from winter to summer conditions is larger over the icelsnow-covered areas than over the two open ocean areas. this is consistent with the warmer and more humid atmosphere above the relatively warm ocean. the cloud amount is large throughout the year for the open water areas, less for the partially ice covered areas to the north and west, and lowest for the central mainland areas. the annual variation in cloud amount is larger for the central mainland and seasonally ice-covered areas than tbe open ocean areas (forland et al. 1997). ny alesund has an ocean-like cloud climate during summer and a more “continental” climate (central mainland) during winter. sugace radiation kudget froin ny-kesulnd: the polar night in ny-alesund lasts from 25 october to 17 february. figure 3a-f shows the annual variation of the s w and lw downward radiation, s w and lw net radiation, the mean srb and the albedo, for the period 1981-1997, on the basis of total daily radiation values. the daily total mean, maximum and minimum radiation values for the 17 years series are included in the figures. most interesting to note is the asymmetry on fig. 3a of the s w radiation with respect to the extra terrestrial global radiation. the maximum surface s w radiation is shifted towards early june with increased mean radiation in spring as compared to the autumn values, due to the higher frequency of clear days in spring (april, may) than in the summer months. because of the high albedo of the snow-covered ground in winter and spring, the successive reflections and multiple scatt ering of the s w radiation between the ground and the atmosphere and clouds will enhance the sw radiation at the surface, hence apparently i n c r e a s i n g t h e a t m o s p h e r i c t r a n s m i t t a n c e . this effect also reduces the difference between clear and cloudy conditions. in contrast, from late june until the end of august multiple reflection is not possible over the low albedo bare ground, causing a larger variation in sw 130 radiation climate variability in svalbard ill short-wavm global mdlatlon ny-aieaund 0 30 60 so 120 160 380 210 240 270 300 330 360 myofyaar (9 long-waw downward radiation nyahmund 9500, , , , , , , , , , , , -71 ic i shori-wava net radialion ny-aimund (dl longwave net radiation ny-abound i i i i i i i i i i i 1 0 30 80 w 120 150 180 210 240 270 xc 330 3 t o my of p a r mean short-wave + longwave downward radiation, albedo (el and transmittmoo ny-jleaund 3w 300 250 2w 150 100 50 0 0 30 50 w im 150 180 210 240 270 300 330 360 my 01 y u r 1 0 0 , , ., , , , , , , , . , , 0 30 m 90 110 150 1m 210 240 270 3w 224 364 day of war o p 80 po 120 i w 180 210 240 no 3~ w s o day of mr f i g . 3 . mean surface radiation budget fluxea from ny-alesund 1981-1997: norwegian polar institute n y h u n d data set with mean. maximum and minimum daily total radiation values of the 17 years series, fhowing the annual variation of the (a) short-wave ( s w ) global radiation, (b) long-wave (lw) downward radiation, ( c ) sw net radiation, (d) lw net radiation, (e) the mean s w l w radiation and tf, the surface albedo. radiation due to changing clear and cloudy weather conditions. the lw downward radiation also shows an asymmetry with peak radiation conditions occur ring during the warm summer months of july and august. the variability of the downward lw radiation is highest during the winter months and much lower in the summer. the large variability during winter reflects the variable weather condi tions with fluctuating clear and cloudy days between periods of stable, cold arctic air and warmer, humid air transported to the arctic by low pressures from the south. during summer condi tions, the warmer and more humid atmosphere increases the downward lw radiation compared to the low winter values. the variance induced by clear and cloudy days is reduced in the summer due to the stable high atmospheric temperature and humidity during clear summer days. the surface albedo shows large annual and inter-annual variations. the maximum and mini mum values are marked with separate curves. from the time the sun turns above the horizon in late february until the middle of may, the albedo remains high above ca. 80%. the small reduction of the albedo in the period is due to the slow 0 r b ~ k et al. 1999: polar research 18(2), 127-134 131 metamorphosis of the snow crystals as the snow cover ages. this change of reflecting properties of the snow speeds up during the melting season, starting in beginning of june. during this period, the albedo drops down to summer values below 20% within a very short time period maximally 15-20 days. then from the end of august the snow returns, though the snow cover may not be permanent until the end of october. as can be seen from fig. 3, the spring melt period occurs within a very narrow time frame with little variation from year to year, whereas the broader autumn transition period with the first snowfall shows a larger inter-annual variability. the period of intense snow melt produce special features in the s w downward radiation (seen in the mean and maximum radiation of fig. 3a), and the lw net radiation (fig. 3d). the data show that the melting period and the onset of melt occurs within a very short time frame each year. during a period of 15-20 days. the albedo drops from above 70% to below 2 0 8 , the lw net radiation decreases as a result of the heated snow cover and gradually snow-free ground, and the s w radiation is reduced to values representative of snow-free ground with no enhancement caused by the high albedo. the increased atmospheric humidity caused by the increased flux of latent heat from the melting surface will also reduce the s w radiation during a short period. however, the radiative effect of the slow increase in the atmospheric humidity and temperature during the period is less than the effect of the heated surface, reducing the lw net radiation. the 17 year averaged mean daily values of s w and lw radiation, surface albedo and atmospheric transmittance are plotted in fig. 4. the plot more easily identifies the asymmetries with respect to midsummer (day 173), as well as the interdepen dence between the global radiation, the albedo and the short-wave transmittance as discussed above. discussion radiation regime of n y k e s u n d is similar to the continental type of the c m during winter and more like the open ocean area south of svalbard during summer. the l w radiation on the northern side of spitsbergen has intermediate values between the c m and the open ocean. this means that the coldest atmosphere is found over the c m during winter, and that the open polynya to the north causes a warmer and more humid atmosphere there. the difference is largest during winter. this is consistent with the albedo variation showing a persistent low albedo on the southern side and intermediate albedos on the partly ice-covered sea on the northern side during winter, with low albedo also for this arfa during summer. the radiation regime in ny-alesund changes with the albedo during spring and autumn. fluctuations are caused by the local ice conditions in kongsfjorden varying markedly from year to year, especially during spring. the high surface albedo in n y h e s u n d and the c m during spring enhance the sw radiation through successive reflections and multiple scat tering of the radiation between the surface and the atmosphere. this is not the case for the open ocean to the south and theo polynya in the north. the cloud amount at ny-alesund is highest during the summer and similar to the ocean areas, while it is lower during the winter. the cloud amount over the central areas is low throughout the year. the longitudinal transect shows simiiar fea tures. the lw downward radiation in ny-alesund is similar to the radiation regime of the central part of spitsbergen during winter. the variation from west to east is similar to the variation from south to north. the s w incoming radiation is similar to the conditions on the western side, with the spring values enhanced by the high surface albedo. the s w radiation is higher over the central island and on the eastern side during the summer, because of the lower cloud amount, higher albedo an$ more sea ice there. the net radiation in ny-alesund evolves, on the other hand, similar to the ocean area east during spring because the retreating high albedo ice cover has similaroradiative effect as the melting snow cover in ny-alesund. the satellite radiation fluxes are compared along two different transects in fig. 4a. b: one long itudinal (west-cm-east) an( one latitudinal (south-cm-north). the ny-alesund radiation conclusions fluxes are plotted in both graphs. the mean lw downward radiation plotted on the latitudinal transect shows clearly that the lw +s shown here, the radiation regime in ny alesund is influenced by the open ocean climate i32 radiation climate variability i n svalbard f i g . 4. satellite radiation fluxes along two different transects: (a) nasa langley srb latitudinal transect 7g81'n. 15-24 'e (south-cm-north); and (b) nasa langley srb longitudinal transect 78". 0g-32"e (west-cm-east). the np ny-alesund srb fluxes are plotted in both graphs. the lower part of each figure shows cloud cover changes along the same transects.-the cloud cover data from ny-alesund are based on manual observations. _ _ _ ~ ~ _ _ ~ sw all sky -78n06e -swall sky-78niqe sw all sky -78n32e lw all sky -78n06e -lwall sky-78n19e lw all sky -78n32e lw -nyaa ,albedo -78n06e ,albedo -78n19e albedo-78n32e -albedo -nyaa total net -78n06e -total net -78nl9e total net -78n32e -net -nyaa sw -nyaa jan feb mar apr may jun jui aug sep o d now dec -swall sky-78n19e sw all sky -81n24e sw -nyaa lw all sky -76n15e -lwaii sky-78n19e lw all sky -81n24e %albedo -76n15e ,albedo -78n19e albedo-8ln24e total net -76n15e -total net -78n19e total net -81n24e -lw n y h -albedo n y h ts 100 e 80 a s 0 f]., 9 m -cloud % -78n19e . cloud % 8 1 n24e 0 0 jan feb mar apr may jun jut aug sep ocl nov dec month . l o o l ! ! ! ! ! ! ! ! ! ! j jan feb mar apr may jun jul aug sep ocl nov dec e 100 ' e m a s 0 3 20 -cloud % -78n19e cloud % -78n32e 5 40 0 0 a jan feb mar apr may jun jul aug sep o d nov dec month to the west (and south) of svalbard during sunimer and autumn, with the arctic sea fog and the low albedo playing a key role. during winter and spring, the radiation regime is of a more continental type, similar to that in the central part of spitsbergen, due to the frozen fiords, drifting sea ice and seasonal snow cover. othe hetero geneous surfaces found in the ny-alesund area (partly ice-covered fiord, vegetated tundra and glaciers) induce local variations in the radiation regime at the station, especially during the melting season in spring. the arctic radiation climate is a combination of open ocean and continental types. there are significant differences between these two radiation regimes induced by the large annual variation of surface albedo and sea ice cover, as well as the ocean-related grctic fog conditions during sum mer. the ny-alesund radiation climate does not represent one typical radiation regime in the 0rbatk et al. 1999: p d u r reseurch / 8 ( 2 ) , 127-134 133 arctic, but rather a combination of different regimes: ocean-like radiation climate during summer and autumn, continental during the winter and spring. this effect must be taken into account when interpreting the long-term variations of the surface radiation fluxes at the station and the atmospheric conditions and circulation patterns. acknowledgements. the satellite srb data set was obtained from the nasa langley research center’s eosdis distrib uted active archive center. the norwegian meteorological institute (dnmi) provided the cloud cover data set from ny alesund. references forland, e. j., hanssen-bauer, i. & nordli, p. 0. 1997: climate statistics and longterm series of temperature and precipita tion at svalbard and jan mayen. dnmi (det norske meteorologiske institutt) klimu rapp. 21. hanssen-bauer, i . , kristensen-solis, m. & steffensen, e. l. 1990 the climate of spitsbergen. (det norske meteorolo giske institutt) dnmi klima rapp. 39. hisdal. v. & finneklsa, 0. 1996: radiation measurements in ny-ilesund, spitsbergen 1988-1992. nor. polarinst. medd. 142. hisdal, v., finnekdsa,0. & vinje, t. 1992: radiation measurements in ny-alesiind, spitsbergen 1981-1987. nor. polarinst. medd. 118. nicholls, n., gruza, g. v., jouzel, j., karl, t. v., ogallo, l. a. & parker, d. e. 1996: observed climate variability and change. in j. t. houghton (ed.): climate change 1995: the science of climate change. pp. 137-192. cambridge: csm bridge university press. orvig, s . 1970: world survey ojclimatologv. vol. 14. climates of the polar regions. new york: elsevier. vinje, t. 1 9 7 6 radiation conditions in spitsbergen in 1973. norsk polarinst. arbok 1974, 205-209. vinje. t. 1977a: radiation conditions in spitsbergen i n 1975. norsk polarinst. arbok 1975, 175-178. vinje, t. 1977b: radiation conditions in spitsbergen in 1976. norsk polarinst. i r b o k 1976, 3 17-3 18. vinje, t. 1978: radiation conditions in spitsbergen in 1977. norsk polarinst. arbok 1977, 293-296. vinje, t. 1979: radiation conditions in spitsbergen in 1978. norsk polarinst. arbok 1978, 67-68. vinje, t. 1980 radiation conditions in spitsbergen in 1979. norsk polarinst. arbok 1979, 57-58. vinje, t. 1982: frequency distribution of sea ice in the greenland and barents seas, 1971-1980. nor. polarinst. arbok 1980. 57-61. whitlock, c. h . , charlock, t. p., staylor. w. f., pinker, r. t., laszlo, i., dipasquale, r. c., & ritchey, n. a. 1993: wcrp surface radiation budget shortwave data product description version 1.1. nasa technical memo 107747. springfield, va: national technical information service. whitlock, c. h., charloek, t. p., staylor, w. f.. pinker, r. t., laszlo, i., ohmura, a,, gilgen, h., konzelman, t., dipasquale, r. c., moats, r. c., lecroy. s. r. & ritchey, n. a. 1995: first global shortwave surface radiation budget dataset. bull. amer. meteorol. soc. 76. 905-922. yamanouchi, t. & 0rbaek, j. b. 1995: comparative study of the surface radiation budget at ny-alesund, svalbard and syowa station, antarctica, 1987. proceedings of the nipr sym posium on polar meteorology and glaciology, no. 9. pp. 118-132. tokyo: national institute of polar research. 134 radiation climate variability in svalbard doi:10.3402/polar.v33.18533 r e s e a r c h / r e v i e w a r t i c l e topography, ice thickness and ice volume of the glacier pedersenbreen in svalbard, using gpr and gps songtao ai,1 zemin wang,1 dongchen e,1 kim holmén,2 zhi tan,1 chunxia zhou1 & weijun sun3 1 chinese antarctic center of surveying and mapping, wuhan university, wuhan 430079, people’s republic of china 2 norwegian polar institute, fram centre, no-9296 tromsø, norway 3 cold and arid regions environmental and engineering research institute, chinese academy of sciences, lanzhou 730000, people’s republic of china keywords gpr; gps; glacier topography; ice volume; ice thickness; pedersenbreen. correspondence songtao ai, chinese antarctic center of surveying and mapping, wuhan university, wuhan 430079, p. r. china. e-mail: ast@whu.edu.cn abstract pedersenbreen is a small valley glacier (ca. 6 km 2 in 2009), ending on land, located in north-western spitsbergen, svalbard. ground-based radio-echo sounding in april 2009, using a 100-mhz commercial radar and a self-made low-frequency radar, revealed a polythermal structure. the radar was coupled with a global positioning system device to geo-reference the traces. each radar profile was manually edited to pick the reflection arrival time from the interface between ice and bedrock. travel times were converted to ice thickness using a velocity of 0.165 m/ns, which was estimated from common mid-point measurement. then the surface topography, bedrock topography, ice thickness contours and ice volume were derived using interpolation methods. because it was difficult to distinguish the reflection wave from the background with the 100-mhz radar in some of the thickest areas of pedersenbreen, we used a 5-mhz radar of our own design to fill in this gap. the maximum thickness of pedersenbreen reaches 18399 m, and the ice volume is 0.39390.047 km 3 in 2009. comparing these data with the surface topographical data available for 1936 indicates a mass loss of nearly 12% during the past 73 years. with 60% of its area covered by glaciers and ice caps (hagen & liestøl 1990), the archipelago of svalbard (74�818n, 10�358e) is dominated by small polythermal glaciers. monitoring and studying such glaciers in svalbard is particularly important since they respond rapidly to climate change and play an important role in sea-level change on decadal to centennial scales (meier 1984; oerlemans & fortuin 1992; hagen et al. 2003). pedersenbreen is a small valley glacier with an area of approximately 6 km 2 located on the peninsula of brøggerhalvøya, north-western spitsbergen, svalbard (fig. 1). its neighbouring glaciers, kronebreen and kongsvegen, have been extensively studied (e.g., hagen et al. 2005; kääb et al. 2005; rolstad & norland 2009; moholdt et al. 2010; köhler et al. 2012). pedersenbreen is, in contrast, poorly studied and basic parameters for the glacier are lacking. this paper presents a base study of pedersenbreen, using information derived from the global positioning system (gps) and ground-penetrating radar (gpr). gpr is an efficient tool for detecting the ice thickness of glaciers, buried ice crevasses, water channel locations and the glacier thermal regime (e.g., macheret & zhuravlev 1982; hagen & sætrang 1991; hambrey et al. 2005; rolstad & norland 2009). we collected more than 45 km of simultaneous gpr and gps profiles on pedersenbreen, from which we retrieved the ice thickness and surface elevation and constructed maps of surface and bedrock topography, and estimated the ice volume of pedersenbreen. data collection gps data since july 2004, a gps tracking station has been set up beside the chinese arctic yellow river station, in ny-ålesund, spitsbergen, svalbard. five observation stakes have been in place along the central line of (page number not for citation purpose) polar research 2014. # 2014 s. ai et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 18533, http://dx.doi.org/10.3402/polar.v33.18533 http://www.polarresearch.net/index.php/polar/article/view/18533 http://dx.doi.org/10.3402/polar.v33.18533 pedersenbreen since july 2005. the movement of these stakes has been monitored annually with high precision using dual-frequency gps instruments (ai et al. 2006; xu et al. 2010). during a two-week period in april 2009, high density gps points were collected on the surface of pedersenbreen using a smart-v1 gps unit (novatel, calgary, ab, canada). though the horizontal accuracy claimed by the manufacturer is within 0.2�1.8 m, in practice this level of accuracy is usually difficult to reach, requiring some additional post-processing of the acquired data. consequently, we reprocessed the gps data to improve its precision, using the procedure described in the methods section below. the five observation stakes (fig. 2b) have also been measured using a dual-frequency gx1230 gps unit (leica geosystems, heerbrugg, switzerland) in april 2009. the highly accurate coordinates from the stakes were utilized to verify the altitude data acquired from the smart-v1 gps unit. gpr profiles the main gpr unit used was the pulseekko pro (sensors & software, mississauga, on, canada). 100 mhz antennas were chosen to survey on pedersenbreen also during april 2009. two antennas were placed horizontally on two all-wood sledges separated by 4 m, and dragged slowly behind a snowmobile so that the two antennas were parallel to each other and perpendicular to the profiling direction. the integrated gps was fixed to the first sledge connecting with the gpr receiver (fig. 2a). the gpr traces with synchronous gps coordinates were collected at one-second frequency. each gpr trace had a time window of 2.8 ms, which was stacked four times and composed of 3500 samples. in total, 16 400 traces were collected, which summed to 45.7 km of distance (fig. 2b). it is of high density such that the average distance between two neighbouring traces was about 3 m. with gpr measurement on glaciers, the absorption and scattering of radio-signals by meltwater, soaked firn and ice lenses increase with radio frequency (smith & evans 1972). for most of the 16 400 traces, the transmitted and reflected signals were clearly presented. a minority of the traces*all acquired over the deepest central cirque area*displayed weak reflected signals. so, a low-frequency (5-mhz) radar (fig. 2c) of our own design was used to collect a few traces along the central flowline of the glacier. these traces were used to verify the depth from high density traces and fill in for missed bed-echoes by the 100 mhz radar. radio wave velocity validation polar ice typically has a radio-wave velocity (rwv) of 0.168 m/ns (paterson 1981). but different glaciers have different temperatures and structures, which results in variable velocities. two common mid-point (cmp) profiles were measured at the tongue of pedersenbreen fig. 1 (a) sketch view of pedersenbreen and (b) map of the main islands of svalbard indicating the location of pedersenbreen. topography, ice thickness and ice volume of pedersenbreen s. ai et al. 2 (page number not for citation purpose) citation: polar research 2014, 33, 18533, http://dx.doi.org/10.3402/polar.v33.18533 http://www.polarresearch.net/index.php/polar/article/view/18533 http://dx.doi.org/10.3402/polar.v33.18533 (fig. 2b). then, the velocity distribution could be acquired using the cmp analysis function of the ekkoview deluxe software. we found that the rwv in the upper layer is higher than in the lower layer of pedersenbreen. this is probably due to the increasing density and the increasing water fraction with increasing depth. based on these results, an approximate velocity of 0.165 m/ns was chosen in this study to process gpr data for pedersenbreen. we should point out that other authors have used a higher rwv, on the order of 0.170 m/ns, for gpr data collected on svalbard polythermal glaciers during springtime (e.g., bælum & benn 2011), which probably implies a relative error in rwv here. methods using the gps points, a digital elevation model (dem) of the glacier surface was derived after data processing with an interpolation method. the dem is the basis for our topographical map of the glacier. data analysis because the smart-v1 gps works at a single frequency, the coordinates acquired directly from the gps were not of sufficiently high precision. from the cross-over points between tracks, we were able to evaluate the precision of the gps survey. there are two kinds of cross-over points. one is the cross-over point between different profiles. the other is the cross-over point within a profile (e.g., a long surveying track turned around and crossed over itself). the statistical data for the height differences are presented in table 1. the data in table 1 indicate that within one profile the height differences were relatively small*root mean square error (rmse) is only 0.23 m*but the height differences between different profiles were much larger, which means that there were systematic errors between different profiles. this was mainly due to variable ionospheric and lower atmospheric conditions as well as satellite distributions between the different profile measurements. to acquire the best possible dem, the height data needed to be improved by reducing the data error between the different profiles as much as possible; our procedure for doing this is presented below. the height data from gps measurements is ellipsoidal height, which needs to be converted into elevation above sea level before further data processing. fortunately, an elevation benchmark near the glacier (b10 km) was found in ny-ålesund whose elevation was determined to fig. 2 (a) the pulseekko pro ground-penetrating radar and global positioning system devices as they were deployed on the glacier pedersbreen. (b) the data points of the survey profiles marked on a map with the wgs84 coordinate system. the grey area marked a (0.48 km2 in 1936 and 0.15 km2 in 2009) is the part of the tongue that retreated during 1936�2009 and is no longer ice-covered. the green area labelled b (0.62 km2) is the northwestern tributary of pedersenbreen, which is inaccessible due to an icefall so there are no survey data for this area. the yellow area marked c (1.10 km 2 ) is the high elevation boundary area, covered with thin snow or firn. the boundary lines are from old maps (norwegian polar institute 1990, norwegian polar institute 2008). (c) self-made low-frequency radar device, whose main parts comprise an oscilloscope (1), transmitter (2), transmitting antenna (3) and receiving antenna (4). table 1 height differences of cross-over points. type count maximum error (m) root mean square error (m) within same profiles 266 2.78 0.23 between different profiles 101 �8.2 2.69 s. ai et al. topography, ice thickness and ice volume of pedersenbreen citation: polar research 2014, 33, 18533, http://dx.doi.org/10.3402/polar.v33.18533 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18533 http://dx.doi.org/10.3402/polar.v33.18533 13.40 m from one map (norwegian polar institute 1990). its gps height was 48.558 m, as determined from gps measurement in april 2009. the geoidal height at this point was then determined to be 35.158 m, which was subsequently used to convert the measured gps heights to altitude above sea level. data adjustment the reasoning that follows is based on the assumption that the altitude correction for a given profile is the same for all of its points; this may not hold true if, for instance, there is a drift with time of the gps-recorded altitude, something not unusual when using a stand-alone gps device. moreover, it is assumed that no data biases are presented. in order to improve the altitude data quality, a least square method was used to process the gps data. assume that each profile needs an altitude corrective variable dhj (j �1, 2, . . ., n; here n is the number of profiles). at each crossing gps point between different profiles, the residual altitude data error vi (i �1, 2, . . ., m; here m is the number of cross-over points) is as in eqn. 1: vi �(hik �dhk)�(hil �dhl ) ; k; l �f1; 2; . . . ; ng (1) here hik and hil are the actual altitude data of the crossover points in the dependent profile k and profile l. dhk and dhl are the altitude corrective variables of the dependent profile k and profile l. then, the least squares method finds its optimum when the sum, s in eqn. 2, of squared residuals is a minimum. s � xm i�1 v2i (2) at the same time we need a rule, eqn. 3, to keep the altitude benchmark. xn j�1 dhj �0 (3) because residual altitude errors remain after the adjustment shown in eqns. 2 and 3, we smoothed the altitude data around the crossing points using an inverse distance weighted method (bartier & keller 1996). the statistical data after this processing are presented in table 2. the data in table 2 show just the internal consistency from gps survey on april 2009. compared with the altitude data of the observation stakes from the dualfrequency gps measurement at coincident points, the accuracy, in absolute value, of the data was calculated to within 0.8 m after smoothing. this data accuracy, which is less than the seasonal variations in the altitude and the year-round melting, was sufficient for our purposes. surface topography from the measured points on the glacier, the dem of the glacier surface can be derived via kriging interpolation from the adjusted and smoothed point data. as the rmse values in table 2 show, the altitude differences between cross-over gps points produced a rough surface, and the processed data show a much smoother surface. a contour map (fig. 3b) was derived from the dem using arcmap software. the planar area was calculated to be 4.462 km 2 within the surveyed extent, which excludes three areas without survey, the unsurveyed tongue area (0.15 km 2 ), the north-western tributary (0.62 km 2 ) and the high elevation uphill boundary areas (1.104 km 2 ). so the planar area should be 6.3490.07 km 2 in total. the error in the planar area was estimated as the product of the glacier perimeter times the uncertainty of 3 m assumed for the positioning of the glacier boundary. bedrock topography and ice volume estimation in the same way as for the surface dem, a bedrock dem was derived using the ice thickness data from gpr combined with the gps locations. but the depth difference between crossing profiles was much larger than the difference in gps height. most depth difference values lie in a gaussian distribution with rmse about 4.6 m, with a few values over 15 m. these discrepancies are probably due to misinterpretation during the ice�bedrock interface picking procedure. in contrast, most gps height difference values lie in a gaussian distribution with a standard deviation less than 1.5 m after adjustment. here we should point out that the 100-mhz radar cannot get a continuously clear reflection signal in the deepest area of the glacier, where temperate ice is probably located (hagen & sætrang 1991). so we used the 5-mhz radar of our own design to get some sparse point data, which filled in the data gap. after the data processing for all the traces from gpr survey, a depth distribution map was obtained (fig. 3a). the bedrock contour map (fig. 3b) was then obtained by subtracting the thickness data from the surface dem. table 2 altitude differences in different types of crossing profiles. type maximum error (m) root mean square error (m) actual data �8.20 2.69 after adjustment �4.01 1.35 after smoothing �0.71 0.29 topography, ice thickness and ice volume of pedersenbreen s. ai et al. 4 (page number not for citation purpose) citation: polar research 2014, 33, 18533, http://dx.doi.org/10.3402/polar.v33.18533 http://www.polarresearch.net/index.php/polar/article/view/18533 http://dx.doi.org/10.3402/polar.v33.18533 results and discussion detailed gpr or gps work has not been performed on pedersenbreen before now. this paper remedies this deficiency by presenting basic elements of the glacier based on high density field surveying data from gpr & gps. we present a surface dem and a bedrock dem of pedersenbreen, containing reliable information including surface topography, bedrock topography, ice thickness and ice volume. these basic parameters are useful for future research on glacier mass balance and numerical model simulation. ice thickness and ice volume calculated from the surface and bedrock dem, the ice volume in pedersenbreen is estimated to be 0.360 km 3 in the surveyed area, i.e., the surface dem-covered area (fig. 3b). according to an empirical formula (hagen et al. 1993), the mean depth of the north-western tributary is 25 m, so its ice volume is estimated to be 0.016 km 3 . similarly, the ice volume of the high-elevation boundary is estimated to be 0.011 km 3 assuming that the mean depth is 10 m here. the ice volume of unsurveyed tongue area is estimated to be 0.006 km 3 with portable gps point data for ensuring front boundary. over the unsurveyed area, there is an uncertainty of 90.015 km 3 given 30% error in unsurveyed tongue volume estimation and 50% error in unsurveyed tributary and boundary areas. simultaneously, there is an uncertainty of 90.022 km 3 for the surveyed area, considering a depth rmse of 4.6 m and the kriging interpolation covariance of 0.4 m. there is also another 3% error, about 0.010 km 3 , considering the rwv difference of 0.005 m/ns. the resulting total ice volume of pedersenbreen was estimated to be 0.3939 0.047 km 3 in april 2009. the maximum depth in pedersenbreen is estimated to be 18399 m at its central area. limited to the surveyed area (4.462 km 2 ), the mean ice thickness is 80.7 m. over the whole glacier, the mean ice thickness is estimated to be 62.0 m, including the uncertain boundary areas and the unsurveyed north-western tributary. bedrock valley feature we have chosen five different profiles across the surface and bedrock and one along the length of the glacier in fig. 4 to present the shape of the glacier. these profiles reveal the bedrock valley shape and different correlations between surface and bedrock. according to the power law model of svensson (1959), the cross-section data is presented by y�axb; (4) where x and y are the horizontal and vertical distances from the lowest point of the cross-section, and a and b fig. 3 (a) depth/ice thickness distribution on pedersenbreen. here, the deepest area presented is under the bottom of the cirque. (b) surface and bedrock topography for pedersenbreen, with 50 m intervals between contour lines. s. ai et al. topography, ice thickness and ice volume of pedersenbreen citation: polar research 2014, 33, 18533, http://dx.doi.org/10.3402/polar.v33.18533 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18533 http://dx.doi.org/10.3402/polar.v33.18533 (commonly used as an index of the steepness of the valley side) are constants. this model has been widely used in the analysis of glacial valley morphology and evolution. some studies suggested that the valley morphology progressively approaches a true parabolic form with increasing glacial erosion, which can be gauged by the proximity of b to 2.0 (svensson 1959; graf 1970). in the case of pedersenbreen, the b values are between 0.71 and 1.89, so the glacier valley of pedersenbreen is overall v-shaped rather than u-shaped (b��2) according to svensson’s model, which is similar to the valley shape of its neighbouring glaciers, austre lovénbreen (saintenoy et al. 2013) and midre lovénbreen (björnsson et al. 1996). additionally, in the lower (profiles p1 and p2) and middle (profile p3) glacier, the bed appears to be less eroded in its western part, while there is not a marked difference between both parts in the upper glacier (profiles p4 and p5). surface and volume change from a historic topographic map from norwegian polar institute, which shows the surface of pedersenbreen in 1936, we can compare the surface elevation change between 1936 and 2009. assuming that the bedrock change is negligible in the past 73 years, the ice volume in the surveying area included in this study is estimated at 0.392 km 3 in 1936 using the surface elevation data according to the old map. the ice volume in the retreated tongue area is estimated to be 0.0316 km 3 , using the currently exposed field as the bed in 1936. again, we neglect the change in the north-western tributary and the uphill boundary area. because of the poor quality in the 1936 map, based on aerial oblique photographs, its error in area and volume is difficult to estimate, so we have omitted them, though they are expected to be large. the length along the central line, the area, the ice volume and the mean ice thickness of pedersenbreen in 1936 and 2009, together with their changes in the period 1936�2009, are shown in table 3. just in the retreated tongue area, which only occupied 5% of the whole area in 1936, the lost mass is contributing ca. 33% of the whole mass loss in the past 73 years. the only available ice volume data of pedersenbreen is 0.46 km 3 in 1977 (hagen et al. 1993), which is calculated fig. 4 profiles and their positions in pedersenbreen in april 2009. profile p3 shows one tributary flowing from the west. profile p5 shows one tributary flowing from the west, and the bedrock of the tributary has been eroded distinctly. the profile along the central flowline of pedersenbreen shows that the surface is relatively smooth but the bedrock is irregular. table 3 comparison in geometric change of pedersenbreen between 2009 and 1936. type 1936 2009 change length (km) 5.18 4.55 �0.63 (12.2%) planar area (km 2 ) 6.48 6.3490.07 �0.14 (2.2%) ice volume (km3) 0.447 0.39390.047 �0.054 (12.1%) mean ice thickness (m) 69.0 62.0 �7.0 (10.1%) topography, ice thickness and ice volume of pedersenbreen s. ai et al. 6 (page number not for citation purpose) citation: polar research 2014, 33, 18533, http://dx.doi.org/10.3402/polar.v33.18533 http://www.polarresearch.net/index.php/polar/article/view/18533 http://dx.doi.org/10.3402/polar.v33.18533 from an empirical formula and is larger than the volume both in 1936 and in 2009. our study suggests that the 1977 volume data is probably an overestimate since we expect that the volume decreased between 1936 and 2009. conclusions the following main conclusions can be drawn from our analysis. the gpr survey in 2009 confirms that pedersenbreen has a polythermal structure, with a layer of temperate ice in the lower part of the central bottom cirque. the glacier valley of pedersenbreen is v-shaped rather than u-shaped. pedersenbreen has experienced a considerable retreat since 1936, with estimated loss in ice volume of 0.054 km 3 during the period 1936�2009, which represents a 12.1% drop during this period. the remarkable mass loss of pedersenbreen is mainly on the tongue area of lower altitude, which contributes ca. 33% to the whole mass loss during the past 73 years. acknowledgements we are very grateful to the anonymous reviewers whose useful comments significantly improved the clarity and presentation of our results. this work was supported by the chinese polar environment comprehensive investigation & assessment programmes, the national high technology research and development program of china (2012aa12a304), the national natural science foundation of china (41076126, 41106163, 41174029, 41176172) and the chinese polar scientific strategy project (20080203, 20100103). the authors thank the chinese arctic and antarctic administration, state oceanic administration, for sponsoring the field surveying and research works around chinese arctic yellow river station. special thanks go to roger w. hagerup and jack kohler from the norwegian polar institute for their help finding the historical maps for this area. we also thank to dr adrian fox from the british antarctic survey for polishing the english of this paper. references ai s., dongchen e., yan m. & ren j. 2006. arctic glacier movement monitoring with gps method on 2005. chinese journal of polar science 17, 61�68. bælum k. & benn d.i. 2011. thermal structure and drainage system of a small valley glacier (tellbreen, svalbard), investigated by ground penetrating radar. the cryosphere 5, 139�149. bartier p.m. & keller c.p. 1996. multivariate interpolation to incorporate thematic surface data using inverse distance weighting (idw). computers & geosciences 22, 795�799. björnsson h., gjessing y., hamran s., hagen j.o., liestol o., palsson f. & erlingsson b. 1996. the thermal regime of sub-polar glaciers mapped by multi-frequency radio-echo sounding. journal of glaciology 42, 23�32. graf w.l. 1970. the geomorphology of the glacial valley cross section. arctic and alpine research 2, 303�312. hagen j.o., eiken t., kohler j. & melvold k. 2005. geometry changes on svalbard glaciers: mass-balance or dynamic response? annals of glaciology 42, 255�261. hagen j.o., kohler j., melvold k. & winther j.-g. 2003. glaciers in svalbard: mass balance, runoff and freshwater flux. polar research 22, 145�159. hagen j.o. & liestøl o. 1990. long-term glacier mass-balance investigations in svalbard, 1950�88. annals of glaciology 14, 102�106. hagen j.o., liestøl o., roland e. & jørgensen t. 1993. glacier atlas of svalbard and jan mayen. meddelelser 129. oslo: norwegian polar institute. hagen j.o. & sætrang a. 1991. radio-echo soundings of sub-polar glaciers with low frequency radar. polar research 9, 99�107. hambrey m.j., murray t., glasser n.f., hubbard a., hubbard b., stuart g., hansen s. & kohler j. 2005. structure and changing dynamics of a polythermal valley glacier on a centennial timescale: midre lovenbreen, svalbard. journal of geophysical research*earth surface 110, f01006, doi: 10.1029/2004jf000128. kääb a., lefauconnier b. & melvold k. 2005. flow field of kronebreen, svalbard, using repeated landsat 7 and aster data. annals of glaciology 42, 7�13. köhler a., chapuis a., nuth c., kohler j. & weidle c. 2012. autonomous detection of calving-related seismicity at kronebreen, svalbard. the cryosphere 6, 393�406. macheret y.y. & zhuravlev a.b. 1982. radio echo-sounding of svalbard glaciers. journal of glaciology 28, 295�314. meier m.f. 1984. contribution of small glaciers to global sea level. science 226, 1419�1422. moholdt g., nuth c., hagen j.o. & kohler j. 2010. recent elevation changes of svalbard glaciers derived from icesat laser altimetry. remote sensing of environment 114, 2756�2767. norwegian polar institute 1990. kongsfjorden, svalbard, scale 1:100000, sheet a7. tromsø: norwegian polar institute. norwegian polar institute 2008. kongsfjorden, svalbard, scale 1:100000, sheet a7. tromsø: norwegian polar institute. oerlemans j. & fortuin j.p.f. 1992. sensitivity of glaciers and small ice caps to greenhouse warming. science 258, 115�117. paterson w.s.b. 1981. the physics of glaciers. oxford: pergamon press. rolstad c. & norland r. 2009. ground-based interferometric radar for velocity and calving-rate measurements of the tidewater glacier at kronebreen, svalbard. annals of glaciology 50, 47�54. s. ai et al. topography, ice thickness and ice volume of pedersenbreen citation: polar research 2014, 33, 18533, http://dx.doi.org/10.3402/polar.v33.18533 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18533 http://dx.doi.org/10.3402/polar.v33.18533 saintenoy a., friedt j.-m., booth a.d., tolle f., bernard e., laffly d., marlin c. & griselin m. 2013. deriving ice thickness, glacier volume and bedrock morphology of the austre lovénbreen (svalbard) using ground-penetrating radar. near surface geophysics 11, 253�261. smith b.m. & evans s. 1972. radio echo sounding: absorption and scattering by water inclusion and ice lenses. journal of glaciology 11, 133�146. svensson h. 1959. is the cross-section of a glacial valley a parabola? journal of glaciology 3, 362�363. xu m., yan m., ren j., ai s., kang j. & dongchen e. 2010. surface mass balance and ice flow of the glaciers austre lovénbreen and pedersenbreen, svalbard, arctic. chinese journal of polar science 21, 147�159. topography, ice thickness and ice volume of pedersenbreen s. ai et al. 8 (page number not for citation purpose) citation: polar research 2014, 33, 18533, http://dx.doi.org/10.3402/polar.v33.18533 http://www.polarresearch.net/index.php/polar/article/view/18533 http://dx.doi.org/10.3402/polar.v33.18533 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <feff004f007000740069006f006e00730020007000650072006d0065007400740061006e007400200064002700e900760061006c0075006500720020006c006100200063006f006e0066006f0072006d0069007400e9002000e00020006c00610020006e006f0072006d00650020005000440046002f0058002d003300200065007400200064006500200063006f006e0064006900740069006f006e006e006500720020006c0061002000700072006f00640075006300740069006f006e00200064006500200064006f00630075006d0065006e007400730020005000440046002000e000200063006500740074006500200063006f006e0066006f0072006d0069007400e9002e0020005000440046002f0058002000650073007400200075006e00650020006e006f0072006d0065002000490053004f00200064002700e9006300680061006e0067006500200064006500200063006f006e00740065006e00750020006700720061007000680069007100750065002e00200050006f0075007200200065006e0020007300610076006f0069007200200070006c0075007300200073007500720020006c006100200063007200e9006100740069006f006e00200064006500200064006f00630075006d0065006e00740073002000500044004600200063006f006e0066006f0072006d00650073002000e00020005000440046002f0058002d0033002c00200063006f006e00730075006c00740065007a0020006c00650020004700750069006400650020006400650020006c0027007500740069006c0069007300610074006500750072002000640027004100630072006f006200610074002e00200049006c002000650073007400200070006f0073007300690062006c0065002000640027006f00750076007200690072002000630065007300200064006f00630075006d0065006e007400730020005000440046002000640061006e00730020004100630072006f0062006100740020006500740020005200650061006400650072002c002000760065007200730069006f006e00200034002e00300020006f007500200075006c007400e9007200690065007500720065002e> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice bookreviews25(2).indd 181polar research 25(2), 181–188 widely read and acknowledged. however, the fi rst and last chapters are also an interesting read and give a nice basis for evaluating the biological and ethnographic material presented in the volume’s middle section, although now and again they are redundant. the book contains an interesting and eclectic collection of black and white illustrations including portraits, historical photographs, and technical and biological drawings. otto fabricius was a cleric, philologist, naturalist and ethnographer. much of his scholarly work stems from the relatively short period of his life spent as a missionary in greenland (1768–1773). his observations during these fi ve years and the experiences he had with greenlandic people clearly left a great impression on fabricius that lasted until his death. unlike many missionaries of his time, fabricius left the european colonytown where he was posted and lived in a greenlandic inuit community. he resided in a house built of stones, turf and timbers and learned the language and the ways of the people. much of their hunting culture revolved around knowing the habits of seals, and hence the people were a wealth of knowledge to fabricius in his faunal and ethnological studies. fabricius is undoubtedly best known for his publication fauna groenlandica (1780), but the work translated by kapel in this book, published a decade later (1790–91), allowed fabricius to expand greatly on the seal material presented in the earlier book. fabricius’s detailed description of the seals of greenland focuses fi rst and foremost on the harp seal or greenland seal (phoca groenlandica), describing: nomenclature; appearance and morphology; distribution (occurrence); behaviour; variation in occurrence and movements; breeding; feeding; predators; hunting methods; utilizabook reviews review of otto fabricius and the seals of greenland. meddelelser om grønland: bioscience 55, by finn o. kapel (2005). copenhagen: danish polar center. 150 pp. isbn 87-90369-77-7. kit m. kovacs norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, kovacs@npolar.no. in this three part volume finn kapel presents us with 1) a brief biography of fabricius, 2) a translation of his treatise on the seals of greenland and, fi nally, 3) a refl ection on the contribution of fabricius as a seal naturalist/scientist. i concur with dr kapel’s belief that the key paper is the second one. this work on greenland’s pinnipeds has until now been available only in danish and german and certainly deserves to be more skull of the “hook-snouted seal”, now known as the grey seal (halichoerus grypus). the drawing illustrated fabricius’s detailed description of the seals of greenland (1791). (reproduced with permission of the danish polar center.) portrait of otto fabricius. (reproduced with permission of the danish polar center.) 182 book reviews tion; parasites; and synonyms. ringed seals (pusa hispida), harbour seals (phoca vitulina), hooded seals (cystophora cristata) and bearded seals (erignathus barbatus) are presented similarly, although more briefl y. fabricius also gives short synopses of four additional “species” reported to him by the greenlanders. three of these animals are either mythical beasts or some sort of biological oddity such as albino specimens. the fourth species summary is the fi rst scientifi c account of the grey seal (halichoerus grypus), which fabricius describes primarily from material in his possession from an island off the danish coast. given the era in which fabricius was writing, his restricted time in greenland, and limited travel in the north, his biological accounts are remarkably insightful. occasionally, they are defi nitively incorrect, such as when he says, “as for the breeding of the harp seal, the matingtime is beyond all doubt in august” when in reality harp seals mate in march. but fabricius can be forgiven for using the size of the embryo in september to back-calculate the time of mating: delayed implantation was unknown in the 1700s. other small slips can be similarly accounted for. he is probably not credited as often as his work warrants; perhaps this book by finn kapel will help correct this situation. if allen’s history of north american pinnipeds (1880) or similar books are on your shelf, otto fabricius and the seals of greenland undoubtedly also deserves a place there. references allen, j. a. 1880: history of north american pinnipeds. a monograph of walruses, sea-lions, sea-bears and seals of north america. washington, d. c.: u.s. geological and geographical survey of the territories. fabricius, o. 1780: fauna groenlandica. (fauna of greenland.) copenhagen(?): j. g. rothe, hafniae & lipsiae. fabricius, o. 1790–91: udførlig beskrivelse over de grønlandske sæle, første og andet stykke. (detailed description of the seals of greenland, parts one and two.) copenhagen: skrivter af naturhistorie-selskabet. review of le monde polaire, mutations et transitions, under the direction of mariefrançoise andré (2005). paris: ellipses– carrefours. 187 pp. isbn 2-7298-2683-1. in french. bernard lefauconnier place du mollard, f-38700 le sappey en chartreuse, france, b.lefauconnier@wanadoo.fr. as mentioned on its back cover, le monde polaire, mutations et transitions comprises part of a collection (carrefours) intended for students of geography, history and the social sciences as well as for a wider public interested in understanding the changes our world is undergoing. other volumes in the series concern, for example, water in the arab world, large cities of north america and international commerce. twelve authors have collaborated on the book. the work is divided into two parts, made up in total of 11 chapters and six brief inset texts. the fi rst part is supposed to present some general aspects of the subject, regional aspects being introduced in the second part. seven of the book’s 11 chapters concern the indigenous peoples of the circumpolar region and constitute the heart of the volume. chapter 3 explores how the inuit conceive of—and are integrated with—their environment. chapter 4 discusses the transition from a subsistence economy to the present situation in the canadian arctic, focussing on nunavik, northern québec. major social transformations are described in chapter 10, with examples from the central canadian arctic. chapter 5 describes the emergence of the sense of an inuit identity, the creation of the inuit circumpolar conference and the building of inuit managerial and administrative competence, especially in the nunavut and nunavik territories, northern canada. chapter 7 concerns the transformation of greenlandic society. the situation of the saami, the subject of chapter 8, is unusual in that this population is represented in four countries: norway, sweden, finland and russia. the relationship between the saami and the norwegian state is described. the small-numbered indigenous ethnic groups—mainly reindeer herders—of the russian arctic are briefl y presented in chapter 9. only two chapters are devoted chiefl y to the 183polar research 25(2), 181–188 physical environment: chapter 1 presents a review of some recent research on the melting of glaciers and the related sea level rise while chapter 2 discusses the impacts of climate change through the metamorphosis of polar landscapes. one chapter (6) describes the development of polar tourism and chapter 11 summarizes past and present scientifi c activities in the antarctic. the limited space allotted to the environment in this book is regrettable. impacts related to climate change are not confi ned to glaciers and landscapes. in a book with academic intentions, references to the arctic climate impact assessment and the arctic monitoring and assessment programme would have been minimally necessary. in chapter 1, one of only two chapters devoted to the environment, some of the research results that are discussed are erroneously interpreted. for example, arendt et al. (2002) estimated the contribution to sea level of alaskan glaciers from the mid-1950s to the mid-1990s to be 0.14 ± 0.04 mm per year. this is equivalent to 5.6 ± 1.6 mm over the period, not 5 cm. another example is where the chapter’s author (incidentally, also the book’s editor), referring to rignot et al. (2003), writes that patagonian glaciers contribute even more than alaskan glaciers to sea level rise. in fact, rignot et al. said that the contribution from the patagonian glaciers is larger than that of alaskan glaciers per unit area. this is an important distinction. finally, the chapter mentions glacier surging but this phenomenon is evidently not understood by the author. there are other fl aws. chapter 6 takes into account the local and regional environmental impacts of tourism but does not mention the contribution to global pollution generated by the transportation of voyagers from low latitudes to the polar areas. in two places—a short inset in chapter 10 and a section heading in chapter 4— the use of the phrase “welfare state” (état providence) seems inappropriate. the texts discuss social and economic transformations and largescale interventions by the canadian central power. the “welfare state” must have been developed to try to counter-balance negative social effects of these transformations and is not in itself the cause of these negative effects. this is a strange book. the title claims to embrace the polar world but only a single chapter concerns the antarctic. the chapters discussing the environment merely skim lightly over a narrow slice of this important topic, without any real look at current climatic changes or the fact that the arctic and antarctic have already been affected by pollution, including ecotoxins, coming from sources elsewhere in the world. even with these drawbacks le monde polaire has value: there are few books presenting a broad picture of circum-arctic peoples. social, economic and geopolitical problems and the similarities and differences in the relationships between far northern indigenous peoples and the modern states that encompass them are briefl y but, in general, clearly described. i was particularly captivated by the subject of chapter 3—“corps inuit, espace géographique et cosmologique”, which opened for me, as an occidental scientist, a new window on the arctic and enriched my vision of it. references arendt, a. a., elchemeyer, k. a., harrison, w. d., lingle, c. s. & valentine, v. b. 2002: rapid wastage of alaska glaciers and their contribution to rising sea level. sciences 297, 382–386. rignot, e., rivera, a. & cassasa, g. 2003: contribution of the patagonia ice-fi elds of south america to sea level rise. science 302, 434–437 review of the north pole, by kathan brown (2004). san francisco, ca: crown point press. 504 pp (xi-xvi). isbn 1891300-18-0. thor b. arlov research and innovation unit, norwegian university of science and technology, no-7491 trondheim, norway, thor.arlov@ntnu.no. at fi rst glance a medium brick sized book entitled the north pole seems a promising read to anyone interested in the arctic, such as this reviewer. unfortunately it does not quite deliver according to expectations, presuming you expect solid information about the polar region. if, however, you are particularly interested in the personal experiences of arctic tourists with a dash of environmental concern, this book may not be a complete waste of time. the author kathan brown is the founder and 184 book reviews director of a renowned san francisco-based fi ne art printing press and publishing house. she has previously published various books on art and artists. however, her professional or personal connection with the polar regions are, as it were, shrouded in northern mists. the introduction to the north pole is not very helpful about her motives for writing this book. it appears she took part in a trip to the north pole sponsored by the american museum of natural history aboard the russian nuclear powered icebreaker yamal in 2002. the following year, she spent a week on a coastal cruise around svalbard. her experiences during these two trips have obviously inspired the book. in addition she has read a number of works about various arctic subjects and talked to some knowledgeable people, but to call this a thoroughly researched book would be stretching it. admittedly, brown seems to have no pretences in this direction. the north pole is voluminous in pages—a little more than half a thousand. the genre is a bit diffi cult to decide as the author mixes forms. since the voyage seems to be the structuring element, i suppose the book might be placed in the travel literature category. following a brief introduction that attempts to explain the somewhat odd composition of the book, there are eight main chapters. the fi rst seven are devoted to the north pole trip on the yamal. each of them is divided into three sections: a personal narrative by the author; excerpts from the journal of fridtjof nansen from the fram expedition; and a conversation with various people rendered in verbatim form. the last chapter is on the visit to svalbard and also contains a conversation, but— quite understandably—no excerpts from nansen. in between there are more than 100 photographs, the vast majority taken by the author herself. to the extent that there are any main themes at all, the issue of climate change and the question who was the fi rst on the north pole (if indeed peary cheated) recur frequently with slight variations throughout the book. if i were to be very polite i would call this unusual lay-out interesting, but to be honest i am rather put off by what seems to be a lack of serious effort making this book. the author’s own, original contribution represents the lesser part of the manuscript. the “journey” sections written by brown make up some seventy pages, or less than 15 % of the book. the photographs, also the work of brown, constitute nearly a quarter of the book. of the remaining 60 %, the excerpts from the journal of nansen fi ll almost 100 pages. the conversations or interview sections, where brown acts as “moderator”, occupy over 150 pages. at the end of the book there is a rudimentary time line, a short bibliography and a decent index. the only map in the book is a poor sketch of the arctic. although neatly organized, this book is in effect a compilation of somewhat disparate elements. by themselves the journey sections work fairly well; brown is a good observer and masters the style of a well-read journalist. she makes a pretty good job of popularizing science. this is the kind of prose one might expect to fi nd in for example national geographic: a personal account supplemented by factual information, or vice versa. the conversation sections function less well. their consistently verbatim form leaves the question open whether editing has taken place or not. anyway, stronger editing would have been desirable—considerable parts of the conversations are just plain small talk between fellow travellers. i kept wondering why the reader is invited to listen in. some of the contributors have more to offer, but the knowledge and capacity of participants like, for instance, arctic climate impact assessment director gunther weller and scott polar research institute archivist bob headland, could have been exploited far better in more elaborate interviews. in general, brown does not seem to distinguish between the substantial and the trivial in her role as moderator. for example, rendering an exchange of opinions concerning rock bands or suvs leaves me, in this context, cold. a more selective approach would certainly not have been amiss. nansen’s journal of his and hjalmar johansen’s dramatic attempt to reach the north pole from fram and their subsequent wintering on franz josef land in 1895–96 is a classic in arctic literature, but should rather be read in the original and in extenso. brown’s excerpts seem out of context and do not lend her account authority—just extra pages. i feel the use of nansen borders on literary theft when the author does not even make the effort of paraphrasing or commenting. finally, the photographs are for the most part unimpressive and appear to be ordinary amateur snapshots. considering the author’s professional background the reproduction is disappointing; the colours seem washed out and the subjects are fre185polar research 25(2), 181–188 quently unsharp. variations on ice fl oes are only interesting to a certain point, which brown oversteps. it does not make things better that there are no captions to the pictures, leaving the reader to guess when, where and why they were taken. in all fairness, kathan brown’s the north pole is probably not intended for well-read polar enthusiasts. it is indeed hard to imagine that readers of polar research will fi nd very much of interest in this book. it is simply too superfi cial with regard the factual parts and has too little to offer in literary terms. in my opinion, neither the gracious contributions of some prominent savants of the arctic nor the extensive quoting of nansen’s diary help salvage this north pole voyage from wreckage. at the uttermost ends of the earth: the physiology of polar fi shes, edited by anthony p. farrell & john f. steffensen (2005). amsterdam: elsevier. 396 pp. isbn 0-12350446-5. andrew clarke biological sciences, british antarctic survey, high cross, madingley road, cb3 oet cambridge, uk, accl@bas.ac.uk. ecologists and physiologists have always been interested in organisms living in extreme environments because of the light they shed on fundamental problems, and the general public has long been fascinated by animals living in climates so inhospitable that unprotected humans would rapidly perish. the pioneering physiologists of the early 20th century had quickly recognized that teleost fi shes with their dilute blood would have real problems in the cold waters of the polar regions, and when johan ruud collected the fi rst scientifi c specimens of an icefi sh he was able to confi rm that there really did exist a group of polar fi shes with no blood pigment. the scene was thereby set for an exploration of the physiology of polar fi shes, and this remains a vibrant fi eld of research to this day. the latest volume of the prestigious fish physiology series brings together a group of distinguished workers in the area of polar fi sh and provides a state-of-the-art survey of our understanding of the physiology of a group of organisms that have successfully adapted to one of the most physiologically challenging marine environments on the earth. the opening chapter (devries & steffensen) provides a brief overview of the marine environment of the polar regions, emphasizing the marked differences between the arctic and antarctic as much as their similarities, and thereby defi ning an important theme for the rest of the book. as well as differences in topography, bathymetry, riverine input and oceanography, attention is drawn to the very different tectonic, climatic, glacial and evolutionary histories of the two polar regions. the latter are fundamental to understanding the very different fi sh faunas of the arctic and antarctic, which are described in exemplary fashion in the second chapter by møller, nielsen & anderson. it is refreshing to see due attention being paid to the systematic and biogeographic aspects of the fauna in a volume devoted primarily to physiology, for this is essential to any complete understanding of evolutionary aspects of the physiology. the systematic treatment also covers all depths, thereby providing a broad context for the traditional (but not universal) concentration by physiologists on the more easily sampled shallow waters. the physiological chapters start with a thorough review of current knowledge of the metabolic biochemistry of polar fi shes by pörtner, lucassen & storch. the main themes of this chapter are the central role played by oxygen in shaping both thermal limits and lifestyle, and the trade-offs inherent in the utilization of energy in a strongly resource-limited environment such as the polar seas. the strengths of this chapter are the way physiological processes are set in an environmental context, the use of a wide range of model organisms, and the links between physiology and ecology. antifreeze proteins and freezing avoidance are reviewed by devries & cheng. the physiological challenge to teleost fi sh living in polar regions was recognized in the 1960s: even with an elevated blood salt concentration, polar fi sh are under cooled by almost 1k. whilst this may seem a small interval, because polar oceans contain ice crystals freezing of these fi sh would be inevitable in the absence of a protective mechanism. the existence of antifreeze glycoproteins and proteins in polar fi sh was quickly established by elegant work by art devries himself, but almost four decades later we are still unravelling the complexities of this system. in addition 186 book reviews to providing a masterly summary of the classical work, the authors also discuss areas of active current research making this the best current review of freezing avoidance in polar fi sh. in the next chapter steffensen concentrates on the respiratory system and metabolic rate; this chapter is thus closely allied to the earlier one by pörtner and colleagues but takes a quite different perspective by concentrating on the organismal rather than the molecular level. steffensen revisits the arguments over the existence of metabolic cold adaptation (mca) in polar fi shes, and does so in a thorough and balanced manner. once a fi sh has taken up oxygen, it then needs to move this oxygen around the body and the circulatory system is described by axelsson. a major factor here is the increase in blood viscosity at low temperature, and it is likely that selection for reduced circulatory costs coupled with the increased solubility of oxygen at low temperatures is what drove the evolution of reduced hematocrit in many polar fi shes and the complete loss of haemoglobin in one group, the icefi sh family channichthyidae. a key feature of this chapter is the discussion of the control of heart rate, setting the antarctic notothenioids in the wider context of non-polar fi sh. wells covers blood gas transport and haemoglobin, principally from studies of notothenioids but also setting the results in a wider context. wells also revisits the topic of mca, coming to a less defi nitive conclusion than steffensen. davison describes the skeletal musculature and locomotion, again principally based on studies of notothenioids. data are compared with warmer water fi sh and the differences related to ecological factors such as growth rate and buoyancy. in exploring the various ways in which temperature may limit muscle performance in polar fi sh, davison also discusses the limitation of mitochondrial atp supply, which links this chapter nicely to that by pörtner and colleagues. the fi nal chapter in the book is an authoritative review of the nervous system of polar fi shes by macdonald & montgomery. how does this volume rate overall? i believe it succeeds in providing a thorough, timely and authoritative survey of the physiology of polar fi shes. it will fi nd a place in my library and i have already found myself making extensive use of it. it is a pity that not every author has taken the opportunity to cover both arctic and antarctic studies, for the book does tend to concentrate on studies of notothenioids in many places. important and interesting as these fi sh are, they are confi ned to the southern hemisphere and physiologists have much to learn from thorough comparative studies. nevertheless this is an excellent summary of current knowledge and will remain for some time the place to go to learn about the physiology of fi shes living at high latitudes. review of the north pole was here: puzzles and perils at the top of the world, by andrew c. revkin (2006). boston: kingfi sher. 128 pp. isbn 0-7534-5993-0. helle v. goldman norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, goldman@ npolar.no. ever wondered what the men’s toilet at camp borneo, a temporary russian camp on the ice about 96 km from the north pole, consists of? in the north pole was here, andrew revkin reveals this—“a waist high igloo-style wall of ice blocks” (p. 16)—and other details of the fi eld conditions experienced by scientists who carry out research near the very top of the world. using revkin’s own visit to the north pole environmental observatory—a science camp set up every year on the ice about 48 km from the north pole—as a jumping off point, the book describes the arctic and our past and ongoing efforts to understand it. climate change is a major theme. other topics, like early exploration of the region and the earth’s shifting magnetism, are also covered. in an enchanting chapter called “the imagined pole”, revkin describes early notions of the far north. we learn, for example, that in ancient hindu / buddhist cosmology, the stars in the sky were tied by ropes of wind to the north star, which was positioned above a gigantic mountain that constituted the world’s centre. four landmasses, divided by great rivers, lay around that centre. three thousand years ago, greek historians supposed that there was a society of “hyperboreans”: “an immortal race of people who lived in happiness and warmth beyond the source of the north wind” (p. 28). (this is sure to raise 187polar research 25(2), 181–188 a smile from readers who, like me, reside north of the arctic circle.) as late as the 19th century some maintained that the earth was hollow, with large openings into the interior at the north and south poles. according to another tenacious and surprisingly recent theory, the north pole was topped by a huge iron cone, which was the source of the planet’s magnetism. the bulk of the north pole was here is set in the present. revkin focusses his account on the scientists who undertake polar research, how they do it and the diverse challenges they face. one chapter begins with this riveting opening: “six of the world’s leading experts at solving arctic riddles are on their knees on the sea ice thirty miles from the north pole, stumped by three broken bolts” (p. 89). the chapter goes on to relate how the bolts were replaced and the winch repaired, and how the equipment contributes to our knowledge of the ocean, atmosphere and climate in the arctic. the heroes of revkin’s book are polar scientists and the divers, technicians and others who work with them. in the harsh environment of the arctic, research teams must combine “the brainpower of scientists with the brute strength of furniture movers, the wile of small-town mechanics, the courage (or recklessness) of extreme athletes, and the willingness to carry a shotgun to ward off polar bears” (p. 92). without oversimplifying its subject matter, the north pole was here makes science accessible to the nonspecialist reader. the slim book is aimed particularly at young adults but will also appeal to their parents. the chapters are short, the type is large and the text is amply illustrated with photographs, diagrams, maps and other illustrations. excerpts from new york times stories relating to the arctic (about half by the author) are sprinkled throughout the book. an award-winning journalist, revkin has been reporting on environmental issues for the new york times for over a decade. some readers may recognize the author’s name from his recent coverage of the bush administration’s attempt to stifl e jim hansen, director of nasa’s goddard institute for space studies, after hansen publicly called for prompt reductions in greenhouse gas emissions. the north pole was here is well timed: 2007-08 is an international polar year, during which scientifi c resources around the world will be concentrated on the arctic and antarctic. its antecedents have taken place in 1882-83, 1932-33 and 1957-58. revkin traces the polar year project back to the inspiration of the austrian karl weyprecht. upon returning from an arctic expedition in 1874, the explorer and scientist was determined to persuade the scientifi c institutions of many nations that it was crucial to coordinate meteorological and geophysical research and to share the resulting data. weyprecht’s efforts bore fruit, though it was posthumous: he died the year before the fi rst polar year. fourteen stations ringing the arctic were established by 11 countries (norway, sweden, finland, austria, netherlands, france, germany, uk, russia, canada, us). revkin observes that the fi rst polar year marked a major change in the culture of science, which became more open, collaborative and self-critical. this book is written with the american reader in mind. for example, the arctic ocean near the north pole is described as “two miles deep— deep enough that ten empire state buildings could be stacked beneath us” (p. 11). that the book tilts decidedly toward a youthful american readership is appropriate. the american association for the advancement of science (1990) has made the point that most schoolchildren in the us are not science literate. it behooves the generation of americans about to come of age to develop a basic understanding of the causes, signs and potential impacts of climate change, as well as to improve their knowledge of other major environ188 book reviews mental problems confronting us, such as natural habitat destruction and loss of biodiversity. the scientists who are spotlighted in the north pole was here are perhaps among the fi rst people to discern the magnitude of human impacts on the natural world; our children may be among the fi rst to have to cope with these changes during their lifetimes. revkin entitled his book after a sign erected by a scientist at the north pole observatory. the joke plays on the fact that the ice supporting the temporary science camp is in constant motion. less amusing are computer simulations according to which the ice on the surface of the arctic ocean may be gone by the end of this century. as is well known in the scientifi c community, this would have radical consequences for the world. let us hope that the north pole was here— a lively paean to polar scientists—is the kind of book that engages young minds in the arctic and in science itself. reference american association for the advancement of science 1990: science for all americans. new york: oxford university press. accessed on the internet at www.project2061.org/ publications/sfaa/online/sfaatoc.htm. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <feff004200720075006700200064006900730073006500200069006e0064007300740069006c006c0069006e006700650072002000740069006c0020006100740020006f0070007200650074007400650020005000440046002d0064006f006b0075006d0065006e0074006500720020006d006500640020006800f8006a006500720065002000620069006c006c00650064006f0070006c00f80073006e0069006e0067002000740069006c0020007000720065002d00700072006500730073002d007500640073006b007200690076006e0069006e0067002000690020006800f8006a0020006b00760061006c0069007400650074002e0020005000440046002d0064006f006b0075006d0065006e007400650072006e00650020006b0061006e002000e50062006e006500730020006d006500640020004100630072006f0062006100740020006f0067002000520065006100640065007200200035002e00300020006f00670020006e0079006500720065002e00200044006900730073006500200069006e0064007300740069006c006c0069006e0067006500720020006b007200e600760065007200200069006e0074006500670072006500720069006e006700200061006600200073006b007200690066007400740079007000650072002e> /nld <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> /esp <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> /suo <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> /ita <feff00550073006100720065002000710075006500730074006500200069006d0070006f007300740061007a0069006f006e00690020007000650072002000630072006500610072006500200064006f00630075006d0065006e00740069002000500044004600200063006f006e00200075006e00610020007200690073006f006c0075007a0069006f006e00650020006d0061006700670069006f00720065002000700065007200200075006e00610020007100750061006c0069007400e00020006400690020007000720065007300740061006d007000610020006d00690067006c0069006f00720065002e0020004900200064006f00630075006d0065006e00740069002000500044004600200070006f00730073006f006e006f0020006500730073006500720065002000610070006500720074006900200063006f006e0020004100630072006f00620061007400200065002000520065006100640065007200200035002e003000200065002000760065007200730069006f006e006900200073007500630063006500730073006900760065002e002000510075006500730074006500200069006d0070006f007300740061007a0069006f006e006900200072006900630068006900650064006f006e006f0020006c002700750073006f00200064006900200066006f006e007400200069006e0063006f00720070006f0072006100740069002e> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice past glaciation and sea levels on bjgrngya, svalbard otto salvlgsen and 0ystein slettemark salvigsen, 0. & slettemark. 0. 1995: past glaciation and sea levels o n bjmnaya, svalbard. polar research b j 0 r n ~ y a has a very thin cover of unconsolidated quaternary sediments. glacial erratics of local origin are spread throughout the lowland areas, and glacial striae indicate glacial movement which was centred in the middle of the island. no traces of the barents sea ice sheet have been observed on b j ~ m 0 y a . nor has there been any postglacial emergence of the island. lake cores date the deglaciation of the lowlands to ca 10,ooo bp, and peat deposits on high mountains show that these were deglaciated before 8700 bp. otto salvigsen and 0 y s l e i n slettemark, no& polarinstiturt, postboks 5072 majorshta. n-0301 oslo, norway. 14(2), 245-251. introduction the reconstruction of the late weichselian ice sheet in the barents sea area is still largely based on indirect evidence, such as the pattern of iso static rebound, undated moraine ridges, general lithostratigraphy and the distribution of over compacted diamicton (elverhei et al. 1993; lam beck 1995). the objective for the present study was to gather new information on glacial features and former sea levels from b j ~ r n ~ y a , which with its position on the western edge of the barents shelf may provide key information in the late weichselian discussion. bj0rnoya is the southernmost island in the sval bard archipelago, 250 km south of spitsbergen and 440 km north of the norwegian mainland (fig. 1). the island is 20 km from south to north, 15 km from west to east, and has a total area of 178 km2. it is situated on a submarine plateau with depths of less than 100 m. the predominantly soft rocks of bjomoya are highly affected by wave abrasion, and the coasts therefore consist almost entirely of steep cliffs (hogvard & sollid 1988). the island can be divided into three geo morphologic regions (fig. 1): the northern plain containing about 700 shallow lakes, the southern mountains which attain an altitude of 440 m a.s.l., and the eastern mountain, miseryfjellet. with its highest peak at 536 m a.s.1. the northern plain is a typical strandflat (nan sen 1922), most extensively developed at about 35 m a.s.1. most of the lakes are small and only a few metres deep, and they are the result of selec tive glacial erosion. the southern parts of the island consist of dolomites, limestones and shales, while the northern plain and miseryfjellet are mainly built up of coal-bearing sandstones and limestones (horn & orvin 1928; worsley & edwards 1976). karst phenomena are common in the limestone areas. large scale features such as dolines, sub terranean drainage, caves and surface collapse features occur in several places. u-shaped valleys, such as ymerdalen (fig. 2) in the southern part of the island, demonstrate former glacial activity. the permafrost is 60-70 m thick, and the upper 0.75 m thaws during the summer (horn & orvin 1928). this paper is based on one month's fieldwork in 1993. transport in the field was exclusively by foot, and the entire island was surveyed. exact positions of observations were obtained by a gps receiver. glacial sediments and erratics the island is covered by a thin and discontinuous layer of quaternary sediments, and large auto chthonous block fields characterise much of the sandstone areas of central bjornoya (fig. 3 ) . a thin (0.5-1.0 m) diamicton is locally exposed in sections along the coastal cliffs. due to its com position and in many cases direct presence above 216 0. saluigsen & 0. slettemark i 74: f-i,q. i . bprnoya. distribution of o h s e n e d glacial striae on bedrock with indication of the direction of movement (toward the observation point. wild black circle). the dotted line on lnset map i s the 500m contour h e which indicates the p o w i o n of the shelf edge past glaciation and sea levels on b j ~ r n @ y a , soalbard 247 fig. 2. bj0rncaya seen from the south. the partly peat covered mountain hambergfjellet in the foreground, and the u shaped valley ymerdalen to thc right of it. glacier sculptured rocks, i t is interpreted as a till, often disturbed by subsequent cryoturbation. numerous cobbles and boulders, some with glacial striae (fig. 4), are found throughout the island, except in the upper mountain areas. the highest observations of erratics are from ant arcticfjellet, about 360 m a.s.1. (fig. 5). horn & orvin (1928) also reported erratics on the north ern plain, for example, a six-metre high heap of sandstones named knorten south of kapp duner, probably the frost-shattered remains of a very large sandstone boulder deposited there by glacial ice. all erratics on b j ~ r n o y a seem t o be of local origin and have been transported only a short distance. traces of marine material on land should be expected if ice from a barents sea ice sheet had overridden the island during the last glaciation. during o u r extensive survey we thoroughly searched for shell fragments and other marine material, but found nothing of the kind. fig. 3. blockfield area from central bjbrneya. 238 0. snliiigsen & 0. slettentnrk n o wb-till sediments o r other unconsolidated sediment5 suspected t o he older than the last glaciation were tound glacial striae the distribution ot observed glacial striae shown in fig. 1 give5 a true image of the quantitative and spatial occurrence of glacial striae on bjarnava. glacial striae were probably fir5t observed h! a . g . nathorst i n 1870 (nathorst 1899). on the westernmosr cape3 of the island. o n e of these f i g . 4 striated ixxhax from the intcrior of bjomoya. c o r n p a s for scale. capes still has the pame rifleodden (riiffeludden) which means "striation cape". the map of horn & orvin (1928) shows the direction of glacial striae observed at about ten different sites. satersmoen & hovden (1984) made observations on the quaternary geology of b j ~ r n ~ y a , and their unpublished report contains another forty obser vations of glacial striae, mainly from the middle and western parts of the island. w e searched the entire island for glacial striae and made about one hundred new observations (salvigsen & slette mark 1993. 1994). t h e glacial striae on bj@rn@ya are best pre fig. 5 . erratic block o n antarcticfjellet past glaciation and sea levels on bj@rn@ya, svalbard 249 fig. 6. striatcd sandstone surface near miketjerna, easternmost bjomoya. glacier movement from the w (from the left on the photo). compass for scale. served in the sandstone areas, whereas the lime stone surfaces seem t o have n o potential for long time preservation. most of the striae were found after digging, brushing and washing bedrock sur faces (figs. 6 and 7), and only a few sites with exposed striations were found o n sandstone sur faces north of miseryfjellet. ice movement directions were in most cases determined from small scale stoss and lee mor phology, but crescentic gouges and large scale features such as roche moutonnkes were also used. n o glacial striae occur in the mountainous areas fig. 7. crossing glacial striae from southwestern bjerneya, near ellasjeen. glacier movement from ene and the se (from the left on the photo). the pencil shows direction of the oldest striae, from the se. and the compass shows the direction of the younger straie. of southern and western b j ~ r n ~ y a , due mainly t o the high degree of weathering on rock surfaces there. t h e northwestern part of the island, with its limestones and calcareous sandstones, is mostly covered by swamps, and the potential for finding striae there is very limited. o n e of the main objectives of our work was to determine whether or not b j ~ r n ~ y a had been covered by or infringed upon by the last barents sea ice sheet. with respect to glacial striae. the coast from miseryfjellet t o nordkapp was most interesting in this context, because any striae from the barents sea glacier in this area would be easy 250 0. salvigseri & 0. slettemark to distinguish from those formed by local glaciers. there a r e numerous roche moutonnees here with more or less well-preserved striae and other small scale glacial features. crossing striae also occur in many places. nearly all the glacial striae o n the eastern part of the island indicate ice movement from the island toward the e and n e , but a more detailed study of age relationship shows that also older striae from an ice movement toward the n a r e preserved in some places. they occur in lee positions and reveal a systematic pattern of development in this area. further west, striae towards nw and s-sw are found, but they a r e also compatible with a local ice sheet centred in the middle of the island. the glacial striae shown o n the m a p are of course not all synchronous. but the age dif ferences are probably not large. the striae in the periphery of the island may be somewhat older than those in the middle of the island. the oldest striae seem to be from a glacier centred on the northern slope of miseryfjellet. most probably a successive displacement of the ice-divide to the middle of the island, northwest of miseryfjellet . then followed. the most numerous traces of glaciation on bjciirnciiya are from glaciers centred there. t h e greatest thickness of ice then probably occurred near the geographical centre of the island. most of the glacial features on bjsrnciiya seem to be from rather rigid ice. and plastically sculp tured forms and features d o not occur. t h e glacial features indicate a modest thickness of the ice cover. and the highest mountains were not necess arily covered by this local ice cap. the main conclusion, however. is that there are no traces of a barents sea ice sheet on bjernciiya. t h e many observed glacial features only indicate activity from local glaciers. t h e presence of such a regional ice sheet o n the island at an earlier stage cannot be ruled o u t , but if it existed, the activity of local glaciers has erased all traces of it. age of the last deglaciation w e know little about the age of the glacial striae, but most probably they represent the latest de glaciation phase o n the island. t h e best minimum ages for the deglaciation of bjsrneya are from datings o n lake sediments. the first lake corings o n bjsrn0ya were carried out by hyvarinen (1968). who cored eighteen lakes and obtained five conventional radiocarbon dates between 8900 and 11,200 yrs bp. however, because of possible contamination with isotopically "dead" carbon from t h e local rocks, the accuracy of these dates could be questioned; hyvarinen concluded that they at least suggested that the sediments in the b j ~ r n ~ y a lakes covered the last 10.000 years. during the ponam 1y93 expedition, new cores were taken from some of the previously cored lakes. a n d ams radiocarbon dates on plant macro fossils (bryophytes) gave ages u p to 9800 years bp (wohlfarth et a]. 1995). confirming the conclusion of hyvarinen (1968) that the sedi mentation in the lakes started about 10.000 years ago. o n the summit plateau of hambergfjellet (440 m a.s.1.) (fig. 2). there is an extensive area of 1-3 m high. peat-covered and ice-cored hillocks (engelskjan 1987). similar mounds also occur on t o p of fuglefjellet (410m a.s.1.). dark brown peat. as well as underlying ice, a r e exposed by erosion in many places, but near-surface perma frost prevented further investigation by digging. t h e frozen peat or the ice lenses seem to rest directly on coarse limestone gravel. samples of peat and moss remnants have been dated, and the bottom sample from a section on fuglefjellet was dated t o 8705 t 120 bp (t-11227). this gives a minimum age for the first peat formation, and thus also for the deglaciation of the higher parts of b j o r n ~ y a . sea levels t h e first geologists who visited b j e r n ~ y a found n o traces of marine action higher than the present beach zone (anderson 1900). horn & orvin (1928), however, advocated a contrasting view and concluded (p. 142). "the last movement of the land in post-glacial times consisted in a sinking to about 35 metres above the present level, followed by an uplifting to t h e present level." however, their observations of rounded pebbles interpreted to have been formed by beach pro cesses a r e highly disputable and have never been confirmed by others. o u r investigations on bjciirn~yn lead us to the conclusion that there are no traces of raised beaches o n t h e island. in some places, especially along the coast north of miseryfjellet, till-covered pust glaciation and sea levels on bj@m@yu, soulburd 251 bedrock surfaces slope modestly and evenly towards the sea until they reach the present beach, revealing that after the deglaciation no sea levels occurred higher than that of the present. the same conclusion can b e made from other sites o n the northern and western coasts, where low land meets the sea. t h e area near the outlet of the small river named benda, on the southernmost plain by the western coast, also demonstrates the non-marine character of the landscape above the present beach zone. a t this site small, modern driftwood logs and other flotsam have been thrown by the waves up to 10 m above sea level, which as far as we know is the highest swell activity observed in svalbard. above that there a r e n o traces of former sea levels. it can therefore be concluded that since the late weichselian deglaciation t h e eustatic sea level rise must have exceeded the isostatic recovery of b j ~ r n ~ y a . in 1864 nordenskiold placed an iron bolt in a rock outcrop in russehamna (fig. 1) and measured the contemporaneous sea level (see horn & orvin 1928). accurate measurements and calculations were thereafter carried o u t in 1922 (horn & orvin 1928), and n o change of sea level was found. at the same time, elevations of a number of triangulation points were determined in relation to the new sea level measurements. these altitudes have recently been compared with the results of tidal gauge measurements through out o n e year, 1989-1990. the conclusion was the same as in 1922, that no measurable sea level changes have taken place on bjornoya in the intervening period (trond eiken pers. cornm. 1995). conclusions only striae from local glaciers occur on b j b r n ~ y a . all displaced rocks found are from the island itself, and n o sediments or rocks from the sur rounding sea bed were transported onto the island during t h e last glaciation. t h e late weichselian glaciation of b j ~ r n o y a has been a local one. and the regional barents sea glaciation did not affect the island. t h e likely age of deglaciation on b j ~ r n ~ y a is no raised beaches or other traces of sea levels about 10,000 yrs bp. higher than the present occur o n b j ~ r n ~ y a . acknowledgements. we are thankful to the people who were involved in our transport to and from bjerneya by respectively the norwegian coast guard vessel grimsholm and the norwegian polar institute vessel lance. the staff of bjerndya radio were most helpful in allowing us to use their huts on the island and the facilities of their station. thanks also to c. hjort, j . y . landvik and k. malmberg persson for valuable comments to preliminary versions of the paper. references anderson, j . g. 1900: den svenska expeditionen till beeren eiland sommaren 1899. ymer 20, 42-454. elverhei, a . , fjeldskaar, w . . solheim. a . nyland-berg. m . & russwurm, l. 1993: the barents sea ice-sheet: a model of its growth and decay during the last ice maximum. q . sci. reu. 12, 86s973. engelskjen, t. 1987: eco-geographical relations of the bjern oya vascular flora, svalbard. polar res. 5 n . s.. 79-127. horn, g. & orvin, a. k . 1928: geology of bear island. norsk polarinst. skr. 15. 152 p p . , 9 pl.. 1 geol. map. hyvarinen, h . 1968: late-quaternary sediment cores from lakes o n bjerneya. geogr. ann. 50a. 235-245. hegvard, k. 6i sollid, j . l . 1988: kystkart svalbard b 5 sdrkapp 1 :200,000. norsk polarinst. temakart 10. lambeck, k . 1995: constraints on the late weichseliian ice sheet over the barents sea from observations of raised shore lines. quat. sci. reo. 14, 1-16. nansen, f. 1922: the strandflat and isostasy. k . norske vidensk. selsk. skr. 1 . 1 1 . kristiania. nathorst, a. g. 1898: om 1898 brs svenska polarekspedition. ymer 18, 321-348. nathorst, a . g . 1899: nigra upplysningar till den nya kartan over beeren eiland. ymrr 19, 171-185. salvigsen. 0. & slettemark, 0. 1993: glacial geology of bjern eya, svalbard. pp. 42-45 in landvik, j . (ed.): ponam field work in svalbard 1993. preliminary report. salvigsen, 0. & slettemark. 0. 1994: nedisningsspor, spesielt isskuringsstriper. p i bjerneya, svalbard. abstracfs 21: n o r diska geologiska vintermotet. lulei. p. 177. sztersmoen. b. h . & hovden, 0. 1984: rapporrfra oppliold pd bj@rn@ya sommereii 1984. report to norsk polarinstitutt and university of bergen. 10 pp, 1 map. unpublished. wohlfarth. b . , lenidahl, g . , olsson. s . , persson. t . , snowball, i . , ising, j . & jones, v. 1995: early holocene environment on bj0rneya (svalbard) inferred from multidisciplinary lake sediment studies. polar res. 1 4 ( 2 ) , 253-275. worsley, d. & edwards, m . b. 1976: the upper palaeozoic succession of bjerneya. norsk polarinsf. arbok 1974, 17-34. research note holocene shoreline displacement in southernmost spitsbergen wieslaw ziaja and om0 salvigsen ziaja, w. & salvigsen, 0. 1995: holocene shoreline displacement in southernmost spitsbergen. polar research 14(3), 339-340. three radiocarbon dates on marine organic material from southernmost spitsbergen are presented, making it possible t o compare the holocene shoreline displacement in this area with that of other areas of svalbard. the most distinct raised beach feature is the large beach ridge terrace about 10 m above sea level which most probably is the result of a marine transgression ca. 6500 years ago. dating of 2700-year-old laminaria from about 2 m above sea level demonstrates a small rising of the land during the youngest holocene. wieslaw ziaja, jagiellonian university, institute of geography. grodzka 64, 31-044 krakbw, poland; otto salvigsen, norsk polarinrtitutt, middelthunsgate 29, p . 0. box 5072 majorstua. n-0301 oslo, norway. a great variety of well-developed raised beaches occur in southernmost sorkapp land (fig. 1). this note deals with marine deposits and features from the middleand late-holocene. the main objective is to demonstrate an eastward increase in shoreline displacement in southernmost spits bergen. other forms of relief and quaternary deposits have been described by wdjcik & ziaja (1993). three samples of marine organic material col lected from sorflya (fig. 1) in 1991 have been dated (table 1). two dates are from the large beach ridge terrace about 10 m above sea level. this prominent geomorphological feature can be followed continuously for a distance of many kilo metres (fig. 1). a whale bone found on top of the ridge terrace 10-20cm below the surface revealed an age of 6465 ? 105 yrs b.p. (t-10860). an identical age was obtained by dating a lami naria layer in the ridge, 9.5m above sea level and 0.7 m below the surface, 6440 * 55 yrs b.p. (t-10859). the latter is a confirmation of a former dating of laminaria from the same site, 6580 & 160 yrs b.p. (gd-6583) reported by wojcik & ziaja (1993). a few kilometres t o the northeast from this site (bettybukta), a whale bone found 9.5 m above sea level revealed the age 6580 ? 50 yrs b.p. (srr-2174 in forman 1990). dating of a layer of laminaria from the left bank of the river near to skjemmeneset and sorkapphytta, about 2 m above sea level, resulted in the age of 2715 ? 85 yrs b.p. the radiocarbon dates presented here are in good accordance with the shoreline diagram for northwestern sorkapp land presented by salvig sen & elgersma (1993). their conclusion was that the holocene transgression there was completed about 7500 years ago and was followed by a relatively stable sea level for about 2000 years. the transgression resulted in a large beach ridge table 1. radiocarbon dates from southernmost spitsbergen, svalbard lab. no. field no. elevation (m) site material age ''c yrs b . p . t-10861 (1) 0.2 skjemmeneset laminaria 2715 * 85 t-10860 (2) 10 aurodden whale bone 6465 ? 105 t-10859 (3) 9.5 mathiasbreen laminaria 6440 ? 55 gd-6583 w6jcik & ziaja 1993 9.5 mathiasbreen laminaria 6580 2 160 340 w . ziaja & 0. salvigsen i.=lsfjorden h.=homsund b.=bellsund f i g . i. location map showing the main geomorphologic featurea of southernmost scrkapp land 1. three sitcs of radiocarbon dated material indicatcd by field nos. "c 111 (skjemmeneset). "c ['i (aurodden). and "c [3] (mathiasbreen, forefield) (see also table 1). 2 holocene terraced coastal plaina. serflya and grunnvagsletta. up to 19 m a.s.1. 3. the main heach ridge terrace, 10 m i l . s . i . 1 . fluvial deposits and allu\,ial fans. s . glaciofluvial extramarginal deposits. 6. old skerries of trollstabbane and scrflyrabbane nith fraxments of raised marine terrace5 2@-10m a.s.1. 7 . lakes. 8. solifluction sediments. 9 . marginal zones of glaciers. 10. glaciers and perennial snow 1 1 . moraines and rock glaciers. 12 rocky slopes with b thin cover of weathered material. 13. rocky wrfaces o i raised cliffs. tcrracea and former skerries. the inset map shows isfjorden ( i ) . bellsund (b) and hornsund (h). terrace which can be followed along the western coast from sorkapp to north of isfjorden (landvik et al. 1987; salvigsen et al. 1990: salvigsen et al. 1991). the top level of this ridge shows some vari ations in altitude from 1 0 m between isfjorden and bellsund (landvik et al. 1987) t o 7 m o n the coast south of hornsund (salvigsen & elgersma 1993). the crest level of the large beach ridge in southernmost sorkapp land has been repeatedly determined by a paulin altimeter in such a way that the uncertainty is less than 2 1 m. w e can therefore conclude that the crest level there is about 3 m higher than the crest level in north western s s r k a p p l a n d . this indicates that the southernmost part of spitsbergen also shows an increased shoreline displacement from the west towards the east during the last 6500 years. w e think that the pattern of relative uplift is mainly caused by different isostatic depression during the last glaciation. thus. our observations indicate a heavy late weichselian glaciation in the sea east of southernmost spitsbergen. references forrnan. s. l (comp.) 1990: svalbard radiocarbon date list 1. occasimal paper n o . 47. instaar, boulder. 48 pp. landvik. j . y . mangerud, j . & salvigsen. 0. 1987: the late weichselian and holocene shoreline displacement on the west-central coast o f svalbard. polar rrs. 5 ms., 2 9 4 4 salvigsen. 0.. elgersma. a , , hjort, c.. lagerlund, e . . liestldl, 0. & svensson, n . 0 . iyyo: glacial history and shoreline displacement on erdrnannflya and bohemanflya. spitsbergen. svalbard. polar rer. 8, 261-273. salvigsen, 0.. elgersma, a . & landvik, j . y . 1991: radio carbon dated raised beaches in northwestern wedel jarlsberg land. spitsbergen. svalbard. w y p r a l r y gcograficmr /la spifsbergen. %l6. salvigsen, 0 . 8: elgersma. a . 1993: radiocarbon dating of deglaciation and raised beaches in north-western s@rkapp land. spitsbergen. svalbard. zesz. nuuk. uj, prace geogr. 94. 39-48. wojcik. a . & ziaja, w . 1993: relief and quaternary of southern sarkapp land, spitsbergen. p o l . polar res. 14(.3). 29s308. doi:10.3402/polar.v34.25718 r e s e a r c h / r e v i e w a r t i c l e haematological values of three antarctic penguins: gentoo (pygoscelis papua), adélie (p. adeliae) and chinstrap (p. antarcticus) andrés e. ibañez,1 roberto najle,2 karen larsen,2 marcela pari,3 amalia figueroa3 & diego montalti1 1 ornithology section, vertebrate zoology division, faculty of natural sciences and museum, la plata national university, paseo del bosque s/n, b1900fwa-la plata, buenos aires, argentina 2 laboratory of cellular biology, faculty of veterinary sciences, centro de la provincia de buenos aires national university, b7000ghg tandil, buenos aires, argentina 3 laboratory of clinical and biochemical analysis, interzonal hospital luisa c. de gandulfo, b1832gvk lomas de zamora, buenos aires, argentina keywords antarctic; haematology; physiology; pygoscelis; penguins; serum biochemistry. correspondence andrés e. ibañez, ornithology section, vertebrate zoology division, faculty of natural sciences and museum, la plata national university, paseo del bosque s/n, b1900fwa-la plata, buenos aires, argentina. e-mail: aeibanez@fcnym.unlp.edu.ar abstract it is established that haematological and biochemical parameters provide important data to assess the physiological condition and health status of wild birds. to undertake conservation physiology or ecophysiology work, it is therefore essential to establish baseline physiological parameters and how these parameters change with age and life history events. in this work, we determined and compared baseline haematology and serum biochemistry between adults and chicks of three antarctic penguin species of the genus pygoscelis: gentoo (p. papua), adélie (p. adeliae) and chinstrap (p. antarcticus). differences in adults among species were observed in haemoglobin and biochemical parameters such as total proteins, glucose and alkaline phosphatase activity. in addition, differences between adults and chicks in haematocrit, haemoglobin, total proteins and glucose concentration were determined. moreover, we evaluated the electrophoretic protein profiles between adults and chicks of the genus pygoscelis, and a conserved protein pattern was observed among species and ages in the genus. altogether, the results suggest that biochemical and haematological differences among pygoscelids may be related to the nutritional status and energetic expenditure during breeding as well as their feeding habits and development stage. haematology and plasma or serum biochemical parameters can provide extremely important information about health status and autecology of free-living vertebrates (balasch et al. 1974; cooke et al. 2013). these analyses consider current nutritional, immune and stress status, but also different seasonal processes related with moult and breeding behaviour. increasing evidence indicates that specific responses against environmental factors may be taxon specific (cooke et al. 2013). the determination of these parameters provides information about the longer-term physiological and ecological processes affecting individuals or populations (ardia 2006). in a nutritional context, body condition typically refers to vertebrates’ stored fat (and protein) reserves (schultehostedde et al. 2005), which are critical in many activities and processes influencing fitness, such as longdistance migration and reproductive success (lill et al. 2013). therefore, establishing reference values and how these values change with age and different life history events is essential for future conservation efforts. migratory birds are exposed to extreme metabolic demands that, together with other factors, such as environmental pollution, stressful situations, physical activity, quality and availability of food resources or health status, can induce changes in plasma biochemistry and haematology (sturkie & griminger 1986; studds & marra 2005). furthermore, all these factors together with human disturbance in breeding sites can limit the individual’s condition, impeding its ability to migrate, breed and survive (studds & marra 2005; carlini et al. 2007). polar research 2015. # 2015 a.e. ibañez et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2015, 34, 25718, http://dx.doi.org/10.3402/polar.v34.25718 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/25718 http://dx.doi.org/10.3402/polar.v34.25718 antarctic birds are important members of the antarctic ecosystem, in terms of total biomass and of interaction with the environment. of particular importance are the penguins, including the three species of the genus pygoscelis: gentoo (p. papua), adélie (p. adeliae) and chinstrap (p. antarcticus), whose breeding range extends south of 608s. in penguins, haematological research has been carried out mainly on blood respiratory properties (lenfant et al. 1969; milsom et al. 1973; nicol et al. 1988; rosa et al. 1993) and on changes in plasma nutrients and metabolites during fasting in breeding season (cherel, leloup et al. 1988; cherel, robin et al. 1988; ghebremeskel et al. 1989; ghebremeskel et al. 1991; ghebremeskel et al. 1992; merino & barbosa 1997; vleck & vleck 2002). notwithstanding the great attention given to penguins because their special adaptations to environmental conditions, there are little reported data about normal haematology and plasma biochemistry of members of the pygoscelis genus (merino & barbosa 1997; najle et al. 2006). moreover, comparisons of haematological reference values of adults and chicks of the genus have not been reported, although it is well established in other birds that development and life history play substantial roles in changing blood chemistry and haematology (wolf et al. 1985; moreira dos santos schmidt et al. 2007). it would be of interest to know whether patterns of haematological ageing observed in other birds are also seen in penguins, as this group is ecologically divergent from most of the world’s birds (williams 1995). the aim of this study was to establish reference haematological and blood biochemical parameters of the three antarctic pygoscelid penguins*gentoo, adélie and chinstrap*using wild birds. in addition, comparisons between adults and chicks of three species were analysed. materials and methods study area the study was conducted on potter peninsula on king george island, south shetland islands, antarctica (62815’0’’s, 58840’0’’w; fig. 1). the official site name and its latitudinal and longitudinal position were obtained from the scar-marbin portal at www.scarmarbin.be/ gazetteer.php?p�details&id�13542. when this work was carried out (15 december 2010 to 15 february 2011), the three species were breeding sympatrically and a total of 14 554 pairs of adélie penguin, 2325 pairs of gentoo penguin and 265 pairs of chinstrap penguin were present. of note, on king george island there are eight scientific bases with hundreds of scientists working throughout the year. also, ongoing and continual movement of aircraft and ships in the area has the potential to contribute to the anthropogenic effects in these zones (rakusa-suszczewski 1998; vodopivez & curtosi 1998; dos santos et al. 2005). sample collection blood samples were collected by venipuncture of the brachial vein from adults (26 gentoos, 18 adélies and 15 chinstraps) and chicks (17 gentoos, 16 adélies and 18 chinstraps) of similar age (15�20 days). peripheral blood fig. 1 study area showing the sampling site, potter peninsula in king george island, south shetland islands, antarctica. haematological values of three antarctic penguins a.e. ibañez et al. 2 (page number not for citation purpose) citation: polar research 2015, 34, 25718, http://dx.doi.org/10.3402/polar.v34.25718 www.scarmarbin.be/gazetteer.php?p=details&id=13542 www.scarmarbin.be/gazetteer.php?p=details&id=13542 www.scarmarbin.be/gazetteer.php?p=details&id=13542 www.scarmarbin.be/gazetteer.php?p=details&id=13542 www.scarmarbin.be/gazetteer.php?p=details&id=13542 www.scarmarbin.be/gazetteer.php?p=details&id=13542 www.scarmarbin.be/gazetteer.php?p=details&id=13542 www.scarmarbin.be/gazetteer.php?p=details&id=13542 http://www.polarresearch.net/index.php/polar/article/view/25718 http://dx.doi.org/10.3402/polar.v34.25718 was obtained using a single 5-ml syringe and a 23-gauge needle. blood samples (approximately 3 ml) were taken immediately, within two minutes after bird capture, to avoid changes in biochemical and haematological parameters due to stress associated to handling (fowler 1999). then the sample was divided and deposited in different test tubes depending on subsequent procedures. briefly, 1 ml of fresh blood was used to determine haematocrit, sedimentation rate, haemoglobin, glucose and electrolytes. on the other hand, 2 ml of blood were used to obtain serum. for this, blood was incubated overnight at 48c and then clotted samples were centrifuged for 10 min at 400 � g. finally, harvested serum was frozen at �208c until determinations were performed in the laboratory. in some cases, blood volumes obtained were small and as a consequence some procedures were applied to all species, but some were only applied to gentoo penguins. haemolysis was not detected in the sera obtained. during the sample collection, each bird was banded with a numbered band to avoid re-sampling. haematological and biochemical analysis haematological and biochemical analyses were carried out on blood samples obtained from adults and chicks of gentoo, adélie and chinstrap penguins. haematocrit, haemoglobin, erythrocyte sedimentation, biochemical metabolites (glucose, total lipid and proteins, urea, creatinin), alkaline phosphatase activity and ion concentration (na � , k � , cl � , ca �2 , p �3 and mg �2 ) were measured. the haematocrit percentage value was determined by the micromethod, haemoglobin level using the cyanmethaemoglobin method (drabkin & austin 1935) and the standard sedimentation value of erythrocytes was calculated in heparinized blood by standing blood vertically in a westergren pipette for 60 min. glucose concentration was estimated using the ortho-toluidine method in a spectrophotometer at 505 nm (nikkila & hyvärinen 1962). in serum, lipid concentration was determined using the sulfo-phospho-vanillin method in a spectrophotometer at 510 nm (frings & dunn 1970). total proteins were quantified by the lowry method. electrolyte concentrations were determined using different assays: sodium (100�200 meq/l), chloride (50�150 meq/l) and potassium (2�10 meq/l) with a konelab 60i prime selective ion analyser (wiener, rosario, argentina), calcium (0�10 mg/dl) and magnesium (0�15 mg/dl) with the colourimetric method (konelab 60i prime) and phosphorus (0�60 mg/dl) with the ultraviolet method (konelab 60i prime). urea, alkaline phosphatase and creatinine were determined by the chemiluminescence method using an architect i1000sr immunoassay analyzer (abbot diagnostics, santa clara, ca, us). all determinations were done in triplicate. agarose gel electrophoresis protein fractions (albumin, a-, b-, g-globulins) and a/g ratio were studied in serum samples (10 ml) from adults and chicks. agarose gel electrophoresis was performed using a semi-automated hydrasys device (sebia electrophoresis, lisses, france). after that, gels were stained with 0.2% amido schwartz solution. an electrophoretic profile of each sample was obtained and analysed using phoresis software. fig. 2 haematological values of gentoo (pygoscelis papua), adélie (p. adeliae) and chinstrap (p. antarcticus) penguins. (a) haematocrit values are represented as mean (9se)% of haematocrit in adults (a) and chicks (c). (b) mean (9se) haemoglobin concentration (g/dl) in adult penguins. sample sizes are given in brackets. significance values are represented by single (pb0.05), double (pb0.01) and triple (pb0.001) asterisks. a.e. ibañez et al. haematological values of three antarctic penguins citation: polar research 2015, 34, 25718, http://dx.doi.org/10.3402/polar.v34.25718 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25718 http://dx.doi.org/10.3402/polar.v34.25718 statistical analysis statistical analysis and plotting were performed using graphpad prism 4 software (graphpad, san diego, ca). normality and homogeneity of variances were tested using kolmogorov-smirnov and levene tests. data were analysed using one-way anova with bonferroni’s posthoc test. for age comparisons in each species, data were analysed using a paired t-test. f ratio and t values are shown in the results, and a p-value less than 0.05 was considered significant. results in tables were expressed as mean9sd, while in bar charts as mean9se for each study group. results haematocrit values from pygoscelis penguins (adults and chicks) are shown in fig. 2a. no differences were determined in haematocrit values among adult gentoo, adélie and chinstrap penguins (gentoo versus adélie p �0.320, f �1.443; gentoo versus chinstrap p �0.268, f �1.732; adélie versus chinstrap p �0.188, f �2.371). in contrast, differences were found when comparing adults and chicks. haematocrit values in adult gentoo, adélie and chinstrap penguins were 1.33, 1.47 and 1.40 times higher than chicks, respectively (gentoo pb0.001, t �8.048; adélie pb0.001, t �6.233; chinstrap pb0.001, t �9.237). differences in haemoglobin concentration were observed among species in adults. gentoo showed higher values than the other species (gentoo versus adélie p �0.038, f �6.714; gentoo versus chinstrap p �0.0097, f �13.429; fig. 2b). in the case of gentoos, haemoglobin value was also determined in chicks (20.7 g/dl 91.6) and the results indicated significantly higher values in adults (pb0.001; t �7.562). in addition, the erythrocyte sedimentation rate in adult gentoo penguins was 1.45 mm/h after 60 min. statistically significant differences in serum glucose concentration were found among species. chinstrap penguins showed higher values than the other species under study (versus adélie p �0.0018, f �28.37; versus gentoo p�0.0008, f�39.69), while glucose level in adélie was higher than in gentoo (p �0.0009, f �35.14). measured total lipid concentrations showed no differences (table 1). gentoo adult penguins showed higher protein concentration than adélie and chinstrap (p �0.026, f�8.238). furthermore, age variation in this parameter was found in gentoo and chinstrap penguins, being higher in adults (gentoo adults versus chicks pb0.01, t �3.149; chinstrap adults versus chicks pb0.001, t �4.92; table 1). reference serum metabolites (urea, creatinin, alkaline phosphatase, sodium, potassium, chloride, calcium, phosphorus and magnesium) for the three pygoscelis penguin species are shown in table 1. the serum protein electrophoretic profile was determined in the species studied in this work in adults and chicks. in all cases, proteins were scattered at least in four peaks corresponding to albumin (alb), a-globulins (a1 and a2), b-globulin and g-globulin. we did not observe differences in the serum globulin fraction. in addition, there was a fusion of a1and a2-globulin fractions in samples of the three species, in both adults and chicks. table 1 serum biochemical reference values for gentoo (pygoscelis papua), adélie (p. adeliae) and chinstrap (p. antarcticus) penguins. mean (9 sd) and sample size (n) of serum biochemistry values are given. superscript letters a(pb0.05), b(pb0.01) and c(pb0.001) indicate statistically significant differences between species, and single (pb0.05), double (pb0.01) and triple (pb0.001) asterisks indicate significant differences between ages. nd: not determined. gentoo adélie chinstrap adults chicks adults chicks adults chicks (n) 22 17 21 16 18 18 serum biochemistry mean9sd mean9sd mean9sd proteins (g/dl) 3.7190.42 a, ** 2.4790.74 4.3990.6 4.2090.43 3.4691.1 a, *** 2.2090.87 lipids (g/l) 8.391.7 nd 7.990.8 nd 8.390.9 nd glucose (mg/dl) 201.2921 c, * 193.0920.71 285.6946 b nd 321.3915.3 b,c, *** 227912.86 urea (mg/dl) 10.592.12a 11.2592.5 15.890.07a 18.6791.15 1395.65 13.6795.03 creatinine (mg/dl) 0.4390.05 0.4790.01 0.3390.30 0.5590.09 0.3490.28 0.3890.27 alk. phosphatase (mg/dl) 108915.56 108.7930.35 120953.55 87.67923.59 7197.07* 138911.31* sodium (meq/l) 142.596.36 15299.055 130920.22 141.795.68 164.7930.6 151.791.52 potassium (meq/l) 2.590.42b 3.5790.25 19.0591.76b 15.8793.33 6.2392.09b 2.790.34 chloride (meq/l) 98.593.53 114.3912.09 125.394.04 11790 131.3938.7 11194.35 calcium (mg/dl) 3.291.41 3.4290.80 5.291.31 3.5391.01 3.2392.04 3.7691.00 phosphorus (mg/dl) 5.3590.21 b 4.8591.34 13.0492.67 b 16.893.1 5.2391.66 4.5390.32 magnesium (mg/dl) 2.290.28 1.4590.62 2.2690.30 2.290.34 1.490.98 1.5690.58 haematological values of three antarctic penguins a.e. ibañez et al. 4 (page number not for citation purpose) citation: polar research 2015, 34, 25718, http://dx.doi.org/10.3402/polar.v34.25718 http://www.polarresearch.net/index.php/polar/article/view/25718 http://dx.doi.org/10.3402/polar.v34.25718 finally, the a/g ratio was similar among pygoscelid adults and lower than chicks (fig. 3, table 2). discussion haematocrit values determined for the three pygoscelis species were similar to those previously described for these penguins and other migratory birds (milsom et al. 1973; myrcha & kostelecka myrcha 1980). no differences were observed in haematocrit among adults, but significant age-related differences were identified. this agrees with the observation that haematocrit value is different for each stage of development, and is associated with physiological processes such as haematopoiesis, which occurs during late embryonic growth and the early post-hatching period. as young animals grow, there is a trend to raise the production of red blood cells, which increases haematocrit value (fair et al. 2007). haemoglobin values were similar to those previously reported for pygoscelids (milsom et al. 1973). gentoo penguins showed higher haemoglobin levels in comparison with adélie and chinstrap, potentially related to gentoo penguins being able to dive deeper distances for longer periods than the other species (williams 1995). the adult�chick differences observed in haematological values (haematocrit and haemoglobin-only in gentoo) are in line with expectations. adults should have a higher oxygen affinity to support adult behaviours such as long continuous diving and swimming (culik et al. 1994). gentoo penguins showed lower glucose concentration than adélie and chinstrap penguins. the glucogenic mechanisms in gentoo penguin are likely to be important because of its feeding habits (aguilera et al. 1993). gentoo penguins feed inshore and are deep divers, and have both greater average prey size and body mass than the other two species. however, values reported here for the penguin species were lower than those described previously (aguilera et al. 1993). lipid concentration is related to nutritional status in free-living birds (jenni-eiermann et al. 2002). serum lipid values were similar to those previously described for these species. in addition, among adult penguins lipids were similar, and this may be because these species have the similar diets which are constituted of krill and fish with high fat content (reinhardt & van vleet 1986; williams 1995). gentoo penguins showed higher protein concentration than adélie and chinstrap penguins, and also age-related differences were identified in gentoo. in addition, some studies have found chick birds to have higher protein levels than adults, whereas others have found the opposite (dawson & bortolotti 1997). this could provide an avenue for future research as it would be interesting to know what proteins make up these differences (e.g., immunological, homeostatic regulation, growth regulation) and what the ecological and fitness roles are for changing protein concentrations across ages. studies of grown birds have been unable to detect age differences. protein electrophoresis is an invaluable diagnostic tool to assess the avian physiological status by determining the relative and total amounts of albumin, a-, b-, and gglobulin fractions. variations in these fractions are related to inflammatory processes, age and nutritional status fig. 3 determination of pygoscelis serum protein fraction by native agarose gel electrophoresis. serum samples from gentoo (pygoscelis papua), adélie (p. adeliae) and chinstrap (p. antarcticus) adults and chicks were assessed in native agarose gel electrophoresis. using phoresis software, by densitometric analyses four peaks were determined in each sample corresponding to albumin, a (a1 and a2), b and g fractions. table 2 blood serum proteins in gentoo (pygoscelis papua), adélie (p. adeliae) and chinstrap (p. antarcticus). values of albumin, a1a2-globulins, b-globulins, g-globulins and a/g ratio are represented as mean (9sd) protein fraction (%) in adult and chick penguins. samples sizes are given in parentheses. gentoo adélie chinstrap adults (3) chicks (4) adults (3) chicks (3) adults (3) chicks (3) fraction (%) mean9sd mean9sd mean9sd albumin 48.6593.18 52.1598.11 48.7391.55 51.1791.92 46.4394.70 54.4592.19 a1a2-globulins 29.492.82 27.1594.93 31.5392.67 30.993.20 33.1797.55 28.3593.18 b-globulins 12.5591.20 10.9894.37 12.2391.57 10.4392.21 14.2391.46 11.292.54 g-globulins 9.490.84 9.7291.67 7.590.0 7.591.65 6.16793.6 692.82 a/g ratio 0.9590.12 1.1390.35 0.9590.05 1.04790.08 0.8790.16 1.1990.10 a.e. ibañez et al. haematological values of three antarctic penguins citation: polar research 2015, 34, 25718, http://dx.doi.org/10.3402/polar.v34.25718 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25718 http://dx.doi.org/10.3402/polar.v34.25718 (grasman et al. 2000). we observed a conserved protein pattern among pygoscelis species and ages, which reflects the close taxonomic relationship of these species. adults showed lower a/g ratio values than chicks. this observation in adults could be a consequence of the energetic costs during breeding, as well because of chronic infection or acute disease, as was reported by others (ots et al. 1998). moreover, the fusion observed in a1and a2globulin fractions was previously described in gentoo and adélie, as a physiologic response to infectious agents and organic compounds in the environment (najle et al. 2006). interestingly, the baseline biochemical values observed in this work differ and were lower in comparison with those previously reported (aguilera et al. 1993), in particular concentrations of protein, glucose, urea, creatinine, alkaline phosphatase, electrolytes and protein fraction patterns. a possible explanation for this is that serum metabolites or proteins may vary in response to specific nutritional, pathological or environmental conditions. supporting our thoughts on this, previous works reported that in different antarctic regions where human activities were significative, modifications in baseline plasma biochemical parameters and immunoglobulin levels were induced in pygoscelis species (barbosa et al. 2007; carlini et al. 2007). sample collection was performed from breeding colonies on king george island, a site with high anthropogenic pressure (harris 1991; carlini et al. 2007). therefore, we believe that the environment could be exerting pressure, modifying baseline serum biochemistry as a physiological adaptation, although further work comparing king george island populations with other less disturbed colonies is needed to confirm this. in this work, we established haematological and serum biochemical reference values for wild antarctic pygoscelis adult and chick penguins. while we acknowledge that sample sizes for some species are small, we consider that the reference values reported here represent basic physiological information from which future comparisons and interpretations can be made. altogether, this information contributes to our knowledge of physiology and their overall health status of these species. once reference values are established, clinical evaluations, ecological physiology and veterinary care will be improved, and this will substantially aid in future conservation efforts. acknowledgements the fieldwork was supported by the argentine antarctic institute, and the protocol of ethical conditions under which this research was carried out was approved by the program of environmental management and tourism (argentine antarctic institute, argentine ministry of foreign, international commerce and worship). we also thank the editors and reviewers for their helpful critiques and comments for improving this manuscript. references aguilera e., moreno j. & ferrer m. 1993. blood chemistry values in three pygoscelis penguins. comparative biochemistry and physiology 105, 471�473. ardia d.r. 2006. glycated hemoglobin and albumin reflect nestling growth and condition in american kestrels. comparative biochemistry and physiology a 143, 62�66. balasch j., palomeque j., palacios l., musquera s. & jimenez m. 1974. hematological values of some great flying and aquatic-diving birds. comparative biochemistry and physiology a 49, 137�45. barbosa a., merino s., benzal j., martı́nez j. & garcı́a-fraile s. 2007. geographic variation in the immunoglobulin levels in pygoscelid penguins. polar biology 30, 219�225. carlini a.r., coria n.r., santos m.m., libertelli m.m. & donini g. 2007. breeding success and population trends in adélie penguins in areas with low and high levels of human disturbance. polar biology 30, 917�924. cherel y., leloup j. & le maho y. 1988. fasting in king penguin. ii. hormonal and metabolic changes during molt. america journal of physiology 254, 178�184. cherel y., robin j.p., walch o., karmann h., netchitailo p. & le maho y. 1988. fasting in king penguin. i. hormonal and metabolic changes during breeding. american journal of physiology 254, 170�177. cooke s.j., sack l., franklin c.e., farrell a.p., beardall j., wikelski m. & chown s.l. 2013. what is conservation physiology? perspectives on an increasingly integrated and essential science. conservation physiology 1, 1�23. culik b.m., wilson r.p. & bannasch r. 1994. under-water swimming at low energetic cost by pygoscelid penguins. journal of experimental biology 197, 65�78. dawson r.d. & bortolotti g.r. 1997. total plasma protein level as an indicator of condition in wild american kestrels (falco sparverius). canadian journal of zoology. 75, 680�686. dos santos i.r., silva-filho e.v., schaefer c.e., albuquerquefilho m.r. & campos l.s. 2005. heavy metal contamination in coastal sediments and soils near the brazilian antarctic station, king george island. marine pollution bulletin 50, 185�194. drabkin d.l. & austin j.h. 1935. spectrophotometric studies. v. a technique for the analysis of undiluted blood and concentrated hemoglobin solution. journal of biological chemistry 112, 105�115. fair j., whitaker s. & pearson b. 2007. sources of variation in hematocrit in birds. ibis 149, 535�552. fowler g.s. 1999. behavioral and hormonal responses of magellanic penguins to tourism and nest site visitation. biological conservation 90, 143�149. haematological values of three antarctic penguins a.e. ibañez et al. 6 (page number not for citation purpose) citation: polar research 2015, 34, 25718, http://dx.doi.org/10.3402/polar.v34.25718 http://www.polarresearch.net/index.php/polar/article/view/25718 http://dx.doi.org/10.3402/polar.v34.25718 frings c.s. & dunn r.t. 1970. a colorimetric method for determination of total serum lipids based on the sulfophospho-vanillin reaction. american journal of clinical pathology 53, 89�91. ghebremeskel k., williams g., keymer i.j., horsley d. & gardner d.a. 1989. plasma chemistry of rockhopper (eudyptes crestatus), magellanic (spheniscus magellanicus) and gentoo (pygoscelis papua) wild penguins in relation to moult. comparative biochemistry and physiology a 92, 43�47. ghebremeskel k., williams t.d., williams g., gardner d.a. & crawford m.a. 1991. plasma metabolites in macaroni penguins (eudyptes chrysolophus) arriving on land for breeding and moulting. comparative biochemistry and physiology a 99, 245�250. ghebremeskel k., williams t.d., williams g., gardner d.a. & crawford m.a. 1992. dynamics of plasma nutrients and metabolites in moulting macaroni (eudyptes chrysolophus) and gentoo (pygoscelis papua) penguins. comparative biochemistry and physiology a 101, 301�307. grasman k.a., armstrong m., hammersley d.l., scanlon p.f. & fox g.a. 2000. geographic variation in blood plasma protein concentrations of young herring gulls (larus argentatus) and caspian terns (sterna caspia) from the great lakes and lake winnipeg. comparative biochemistry and physiology c 125, 365�375. harris c.m. 1991. environmental effects of human activities on king george island, south shetland islands, antarctica. polar record 27, 193�204. jenni-eiermann s., jenni l. & piersma t. 2002. plasma metabolites reflect seasonally changing metabolic processes in a long-distance migrant shorebird (calidris canutus). zoology (jena) 105, 239�246. lill a., yachou-wos l. & johnstone c.p. 2013. are haematocrit and haemoglobin concentration reliable indicators of body condition in adult welcome swallows? emu 113, 93�98. lenfant c., kooyman g.l., elsner r. & drabek c.m. 1969. respiratory function of blood of the adélie penguin, pygoscelis adeliae. american journal of physiology 216, 1598� 1600. merino s. & barbosa a. 1997. haematocrit values in chinstrap penguins (pygoscelis antarctica): variation with age and reproductive status. polar biology 17, 14�16. milsom w., johansen k. & millard r. 1973. blood respiratory properties in some antarctic birds. condor 75, 472�474. moreira dos santos schmidt e., paulillo a.c., locatelli dittrich r., santin e., linder da silva p.c., beltrame o. & gonçalves de oliveira e. 2007. the effect of age on hematological and serum biochemical values on juvenile ring-necked pheasants (phasianus colchicus). international journal of poultry science 6, 459�461. myrcha a. & kostelecka myrcha a. 1980. hematological studies on antarctic birds i. hematological indices in some species of the birds studied during australian summer. polish polar research 1, 169�173. najle r., solana h.d., bottino d., juáres m.a., mauad m. & montalti d. 2006. the use of serum proteins as biological markers of contamination of gentoo pygoscelis papua and adelie p. adeliae penguins. revista internacional de contaminación ambiental 22, 107�112. nicol s., melrose w. & stahel c.d. 1988. haematology and metabolism of the blood of the little penguin eudyptula minor. comparative biochemistry and physiology a 89, 383�386. nikkila a. & hyvärinen a. 1962. specific determination of blood glucose with o-toluidine. clinica chimica acta 7, 140�143. ots i., murumagi a. & horak p. 1998. haematological health state indices of reproducing great tits: methodology and sources of natural variation. functional ecology 12, 700�707. rakusa-suszczewski s. 1998. the past and present of king george island (south shetland islands, antarctica). polish polar research 19, 249�252. reinhardt s.b. & van vleet e.s. 1986. lipid composition of twenty-two species of antarctic midwater zooplankton and fish. marine biology 91, 149�159. rosa c., rosa r., rodrı́guez e. & bacila m. 1993. blood constituents and electrophoretic patterns in antarctic birds: penguins and skuas. comparative biochemistry and physiology a 104, 117�123. schulte-hostedde a., zinner b., millar j.s. & hickling g.j. 2005. restitution of mass-size residuals: validating body condition indices. ecology 86, 155�163. studds e. & marra p.p. 2005. nonbreeding habitat occupancy and population processes: an upgrade experiment with a migratory bird. ecology 86, 2380�2385. sturkie p.d. & griminger p. 1986. body fluids: blood. in p.d. sturkie (ed.): avian physiology. 4th edn. pp. 102�129. new york: springer. vleck c.m. & vleck d. 2002. physiological condition and reproductive consequences in adélie penguins. integrative and comparative biology 42, 76�83. vodopivez c. & curtosi a. 1998. trace metals in some invertebrates, fishes and birds from potter cove. berichte zur polarforschung 299, 296�303. williams t.d. 1995. the penguins. spheniscidae. bird families of the world. oxford: oxford university press. wolf s.h., schreiber s.w., kahana l. & torres j.j. 1985. seasonal, sexual and age-related variation in the blood composition of the brown pelican (pelecanus occidentalis). comparative biochemistry and physiology a 82, 837�846. a.e. ibañez et al. haematological values of three antarctic penguins citation: polar research 2015, 34, 25718, http://dx.doi.org/10.3402/polar.v34.25718 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25718 http://dx.doi.org/10.3402/polar.v34.25718 no job name guest editorial—the ballyhoo over polar bearspor_137 323..326 doi:10.1111/j.1751-8369.2009.00137.x critics have said that there’s little or no justification for the focus that polar bears (ursus maritimus) have received as a threatened species. recent studies project dramatic reductions in polar bear numbers in just a few decades, in concert with the equally dramatic reduction in critical sea-ice habitat, yet there are undoubtedly ecologically more “important” species in tropical and temperate latitudes that are facing equal or more urgent problems at present. however, there is hardly any other species that has the potential to capture people’s attention more effectively than the “king of the arctic”. this is a large part of the picture when trying to get a grip on the ruckus that has been going on in some arctic countries after the turn of the millennium, and especially since 2005. here, i draw upon insights gained in my capacity as senior adviser to the norwegian ministry of the environment in arctic matters, and as a member of the polar bear specialist group (pbsg), to reflect on recent important events in the international conservation of polar bears. polar bears, as reviewed by the international union for conservation of nature (iucn) species survival commission (ssc) pbsg, are divided into 19 populations inhabiting various parts of the circumpolar arctic (aars et al. 2006; see also pbsg 2009). although there are huge knowledge gaps, especially in russia, eastern greenland and in the arctic basin, the world population of polar bears is estimated to be about 20 000–25 000. polar bear populations in this context are not really true populations in the strict biological sense. polar bears seem to be genetically similar around the arctic, which means that the animals are mating across the boundaries of the so-called populations at a rate high enough to prevent genetic distinctions from arising between populations. however, decades of data on movement and migration patterns—thanks in very large part to satellite telemetry technology—have given some support to the current delineation of populations, and as these units have been helpful as management units, the population delineations have been kept. except in norway and in russia, where they are totally protected, polar bears are harvested throughout the species’ range. the establishment of management units, or “populations”, has proven to be helpful when developing and implementing management regimes. although there are polar bears in the arctic basin, the basin is not regarded as a separate management unit or population. the densities of polar bears there are expected to be low, and as jurisdictional and cost issues are problematic, there is, and will be, little or no knowledge collected about bears in this part of the species’ range. one of the really troublesome facts that causes a lot of bad publicity for polar bear scientists and management authorities around the arctic is that the bear’s status as a threatened species doesn’t jibe with the fact that most polar bear populations have appeared to be in good shape for a while. and the problems that have been observed in some populations have essentially been caused by overharvesting, not climate change, although it’s the latter that has been putting polar bears on the front pages of newspapers and magazines lately. over-harvesting has been the obvious culprit for almost a century (see “from the institute’s photo library”, at the end of this issue). concern about harvest levels led to initial talks between the arctic nations in 1965, which culminated in the signing of the agreement on the conservation of polar bears in 1973. the signatories were canada, denmark, norway, russia and the usa. all five polar bear nations were on board. the climate threat that is now making headlines isn’t really like any other threat we have dealt with (although polar bears may have experienced marked climate change many thousands of years ago; see ingólfsson & wiig 2009 [this issue]). in the past, relatively high thresholds for agreeing on and implementing management actions to mitigate the impacts of threat factors have always allowed the effects of threats to manifest in the populations in question before management has acted upon it. however, the projected scale and speed of climate warming, and the incredibly dramatic consequences that are predicted, force us to act largely before we have seen clear and undisputable effects of climate change manifest in most populations. global awareness about climate change exploded at the turn of the new century, based on a long-term scientific modelling and documentation effort, as presented in the third assessment report of the intergovernmental panel on climate change (houghton et al. 2001). as the impact global warming would have on the frozen expanses of the north, and consequently on polar bear habitat, began to correspondence dag vongraven, norwegian polar institute, polar environmental centre, no-9296 tromsø, norway. e-mail: vongraven@npolar.no polar research 28 2009 323–326 © 2009 the author, journal compilation © 2009 blackwell publishing ltd 323 mailto:vongraven@npolar.no be understood, the fate of polar bears was suddenly brought front and centre. this rapidly emerging awareness prompted the iucn to commission an assessment of the projected status of polar bears from their dedicated specialist group, the pbsg. this assessment, first presented at the 14th meeting of the pbsg in seattle in 2005 (aars et al. 2006; see also iucn 2009), concluded that there was a real risk that the world’s populations of polar bears could be reduced by 30% or more within three polar bear generations, i.e., within 45 years. it was therefore suggested to “upgrade” u. maritimus from the iucn’s red list of threatened species category of least concern (lc), which in practice means no additional conservation actions are necessary, to vulnerable (more precisely, vu a3c), where the need for actions starts to kick in. all the polar bear countries are members of the iucn, and thus they are obliged to “support and facilitate the objectives, activities and governance of the iucn” (iucn 2008). russia has its own red list classification, unchanged for many years, but polar bears have been protected in russian territories since 1956. norway acknowledged the polar bear’s new iucn red list status in its updated national red list published in 2006; in 2007, so did denmark/greenland. that left only the usa and canada. in the usa, a petition to list the polar bear as a threatened species under the endangered species act (esa) was submitted in february 2005, giving the management authorities—the us department of the interior and its environmental directorate, the us fish and wildlife service (fws)—a period of up to two years to finally decide whether polar bears should be listed. after being sued for slow progress in december 2005, the fws stated that protection of polar bears “may be warranted”, and a full status review was initiated. the fws proposed listing the species as threatened in january 2007, leaving them until january 2008 to make a final decision. as part of this full status review, a set of reports was commissioned from the us geological survey. one of the general conclusions of these reports was that “projected changes in future sea ice conditions, if realized, will result in loss of approximately 2/3 of the world’s current polar bear population by the mid 21st century” (usgs 2008: 2; see also amstrup et al. 2007). still not meeting their deadline, which was january 2008, the us government was sued again, before a final decision was made on 15 may 2008 to classify the polar bear as a threatened species. canada has still not met its obligations as an iucn member. the “red list instrument” in canada is the committee on the status of endangered wildlife in canada (cosewic). thirteen of the 19 globally recognized populations of polar bear are partly or fully under canadian jurisdiction, and they comprise about twothirds of the world’s number of polar bears. all canadian populations are harvested, and subsistence hunting in local inuit communities is a strong incentive to maintaining the status quo. this may also have encouraged the canadian government to give the most eager climatesceptic among experienced polar bear scientists the task of assessing the status of polar bears for cosewic in 2008. not surprisingly, the assessment concluded that the polar bear in canada—all 13 populations were treated as one—was to be considered as a species of “special concern”. this is the same status polar bears have had in canada since 1991. in practice, it means that the species might become threatened in the future, but for now we can go on with business as usual. in canada, species of special concern should be reassessed within 10 years, but 10 years is a long time, especially in a country where pressure from harvesting is quite high and out of control in some areas, as is the case with the populations shared polar bear and seagull. (photo by morten ekker.) polar bear tracks, barents sea. (photo by sebastian gerland; courtesy of the norwegian polar institute photo library.) guest editorial polar research 28 2009 323–326 © 2009 the author, journal compilation © 2009 blackwell publishing ltd324 between canada and greenland. has canada replaced the usa as the “bad guy”? the usa process was watched closely throughout the circumpolar arctic. it was obvious that this was a big issue in the usa, with many real and perceived consequences. the fws didn’t find it easy either, and in spring 2007 the agency sent an e-mail to high-ranking environmental officials in the norwegian government exploring the possibility of arranging a meeting in shepherdstown, west virginia, in june 2007. the fws was in need of some help and advice from the other polar bear nations on what to do. the fws was very careful to call it a meeting of the “polar bear range states” or a “technical meeting”, as opposed to a meeting of the parties of the 1973 agreement: the us agency had no interest in opening discussions on the whole range of issues covered by the agreement. two of the thorniest problems that the fws grappled with were trophy hunting and recovery plans. trophy hunting: until 1994, the us marine mammal protection act prohibited americans from importing polar bear trophies into the usa. however, in 1994, as a result of pressure from the hunting lobby, amendments to the law made it possible for americans to pay for the right to hunt “quota bears” in “approved” canadian polar bear populations, and to bring the hides back to the usa. listing polar bears as a threatened species under the esa would reverse this. recovery plans: the esa requires that plans for the conservation and survival of threatened species are developed and implemented. in the polar bear case, such recovery plans would have to deal with a fast reduction of arctic sea-ice cover, as a projected reduction in sea-ice habitat was the reason for the petition in the first place. recovery plans involving sea ice would imply a substantial change in the level of acceptance of climate change by the bush administration. in short, if the us government classified polar bears as threatened, it would be on the grounds of climate change projections, which the nation’s leadership had been refuting. the shepherdstown meeting was a success, not least in convincing the other nations that the usa didn’t have any hidden agenda. there were no written and signed statements from the meeting in which us authorities could find authoritative support for going on with “business as usual”, as was the fear of some of the attendees. one of the outcomes of the shepherdstown meeting was that norway was asked to host a new meeting of the parties to the 1973 agreement. representatives of the signatory nations met in tromsø in march 2009. there was still some reluctance on the part of some delegations to call this a “meeting of the parties”—some kept referring to the meeting as a “range states meeting” or a “technical meeting on polar bears”. this reluctance was rooted in the usa and canadian administrations’ fear of a full-scale and public discussion of the wide range of political issues relevant to polar bear conservation at the time. this and other controversies, such as the absolute refusal by greenland and canada to have an open meeting that would include the press and other media, surfaced the week before the meeting, almost derailing the entire event before it even took place. norway’s intense diplomatic efforts during the last week before the meeting got things back on track. as a compromise, norway gave in to greenland’s and canada’s insistence on barring the media from parts of the meeting. contrary to many of the sceptics’ predictions, the outcome of the meeting was perceived as being positive. in the final statement, climate change was stated as being the most important threat to polar bear conservation. the work carried out by the pbsg in taking care of the agreement during the years after 1981 was also formally recognized, and the pbsg was consequently asked to serve as a scientific adviser to future regular meetings of the parties. specifically, the pbsg was asked to give input to a circumpolar action plan for the conservation of polar bears. even the pbsg delegates themselves were content with the meeting outcome, surprised as they were. when the pbsg met for its 15th meeting in copenhagen a few months ago, in the summer of 2009, the backdrop was quite different than for most meetings since the beginning of the 1980s. for the first time since 1981 the parties to the 1973 agreement had met, revitalizing international cooperation on polar bear management. although matters pertaining to the agreement have been diligently looked after by the pbsg in the meantime, most people involved believe it is a good thing that the parties become more engaged in polar bear conservation. this will probably introduce more politics into polar bear management, but it is hoped that, on balance, greater involvement by the polar bear nations will benefit polar bears. although media coverage about a supposed “banning” of a climate-sceptic and previous long-time member of the pbsg, now without affiliation to any jurisdiction, made some noise at the meeting, the meeting was productive in responding to the nations as an authoritative and scientifically independent group. the new review of the 19 populations currently recognized shows that of the 12 populations on which there are sufficient data, one population is increasing, three are stable and eight are decreasing in size. the previous review, made in 2005, was that of these same 12 populations: two were increasing, five were stable and five were decreasing. there has been a change for the worse. even though over-harvesting is still the main guest editorial polar research 28 2009 323–326 © 2009 the author, journal compilation © 2009 blackwell publishing ltd 325 culprit, there are more and more indications that climate warming is starting to have consequences for the condition and well-being of polar bears, and that climate change is the single greatest challenge to the species in the near future. another notable threat, especially pronounced in some areas, is the effects of ecotoxins that are transported to the arctic by air and sea currents, and that build up in the food chain, in which the polar bear is at the top (see, for example, horton et al. 2009 [this issue]). in spite of the steps forward taken this year, the future of polar bears is still looking grim. even so, there is a sentiment among the majority of the members of the polar bear scientific community that however dark things might look there is still time to reverse the situation, or at least to ameliorate it. mitigations to reduce emissions of greenhouse gases will still work to the benefit of polar bears. scientific work being carried out now shows this beyond doubt. references aars j., lunn n.j. & derocher a.e. (eds.) 2006. polar bears. proceedings of the 14th working meeting of the iucn/ssc polar bear specialist group, 20–24 june 2005, seattle, washington, usa. occasional paper of the iucn species survival commission 32. gland: international union for conservation of nature and natural resources. amstrup s.c., marcot b.g. & douglas d.c. 2007. forecasting the range-wide status of polar bears at selected times in the 21st century. administrative report. reston, va: us department of the interior and us geological survey. horton t.w., blum j.d., xie z., hren m. & chamberlain c.p. 2009. stable isotope food-web analysis and mercury biomagnification in polar bears (ursus maritimus). polar research 28, 443–454. houghton j.t., ding y., griggs d.j., noguer m., van der linden p.j., dai x., maskell k. & johnson c.a. (eds.) 2001. climate change 2001: the scientific basis. contribution of working group i to the third assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. ingólfsson ó. & wiig ø. 2009. late pleistocene fossil find in svalbard: the oldest remains of a polar bear (ursus maritimus phipps, 1744) ever discovered. polar research 28, 455–462. iucn (international union for the conservation of nature) 2008. statutes, including rules of procedure of the world conservation congress, and regulations. gland: international union for conservation of nature and natural resources. iucn (international union for the conservation of nature) 2009. iucn red list of threatened species. version 2009.1. accessed on the internet at http://www.iucnredlist.org on 25 september 2009. pbsg (polar bear specialist group) 2009. population status reviews. accessed on the internet at http://pbsg.npolar.no on 25 september 2009. usgs (us geological survey) 2008. usgs science to inform us fish and wildlife service decision making on polar bears. executive summary. accessed on the internet at http://www.usgs.gov/newsroom/special/polar_bears/ on 25 september 2009. guest editorial polar research 28 2009 323–326 © 2009 the author, journal compilation © 2009 blackwell publishing ltd326 http://www.iucnredlist.org http://pbsg.npolar.no http://www.usgs.gov/newsroom/special/polar_bears no job name r e s e a r c h n o t e por_162 451..454 melting sea ice for taxonomic analysis: a comparison of four melting procedures ditte marie mikkelsen1 & anzdrej witkowski2 1 greenland institute of natural resources, po box 570, dk-3900 nuuk, greenland 2 university of szczecin, waska 13, pl-71-475 szczecin, poland abstract the influence of four melting procedures on the taxonomic composition of the sea-ice algal community in kobbefjord, south-west greenland, was investigated in april 2008. direct melting (at 4 and 20°c) was compared with melting in buffering seawater (with salinities of 10 and 30). the sea-ice algal community consisted of diatoms, cysts and several flagellate groups. direct melting at 20°c differed significantly from one or more of the other melting procedures regarding the flagellate groups chrysophytes, chlorophytes, dinoflagellates and unidentified flagellates, whereas diatom, cyst and cryptophyte abundance was similar, regardless of the melting procedure. apart from chrysophytes, the three other melting procedures (direct melting at 4°c and buffered in seawater with salinities of 10 and 30) were not statistically different. it is recommended that direct melting at 20°c is avoided, whereas the three slow melting procedures are all comparable. this will enable the future comparison of data from a wide geographic and historical range, thereby increasing our knowledge of sympagic algal communities. keywords buffer; diatoms; direct melt; flagellates; osmotic stress; sea ice. correspondence ditte marie mikkelsen, greenland institute of natural resources, po box 570, dk-3900 nuuk, greenland. e-mail: dittemikkelsen@gmail.com doi:10.1111/j.1751-8369.2010.00162.x during the course of sea-ice formation, consolidation and melt, a community of bacteria, viruses, algae and protozoa occupy the three-dimensional brine network. the sea-ice habitat is highly variable, both regarding chemical and physical parameters, and the primary producers of the system are diverse. pennate diatoms are generally considered to be the dominant group (medlin & priddle 1990). apparent geographic or temporal variations in the taxonomic composition of sea-ice algal communities may be real, but could also be caused by differences in methodology. melting sea ice is an area of particular concern. when sea-ice samples are melted, the algae are exposed to a salinity change, and thus to osmotic stress, which may cause cells to lyse. taxonomic analysis by microscopy subsequent to sea-ice melting may therefore be biased, depending on the susceptibility of the cells, and organisms with rigid cell material could be overestimated (garrison & buck 1986). the consequence of osmotic stress during sea-ice melting could be an erroneous analysis of taxonomic composition. one option to avoid the melting process is brine drainage, but as organisms attached to the ice lattice and caught in brine inclusions will not drain, sampling constitutes less than 5% of the sea-ice volume (haecky & andersson 1999). although a comparison of sea-ice melting processes on a single ice floe showed similar community composition (garrison & buck 1986), brine drainage may inadequately reflect the actual sea-ice algal community because of differences in, for example, the microhabitat (e.g., suspended or attached) and morphology (e.g., setae or mucoid substances) of sea-ice algae. taxonomic community studies should ideally include the entire sea-ice column, from top to bottom, ensuring that all organisms are sampled. different approaches have been taken to mitigate osmotic stress during melting, most frequently by buffering the melting sea ice in an ample volume of pre-filtered seawater of known salinity (von quillfeldt 1996, ikävalko 1998). however, brine salinity varies temporally and vertically, e.g., from <1 to 70 over the course of a sea-ice season (mikkelsen et al. 2008). buffering sea-ice samples in seawater with a salinity of 33 would still cause the algae to experience osmotic stress. one way to reduce this osmotic stress would be to calculate the brine salinity immediately, and then use a polar research 29 2010 451–454 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 451 mailto:dittemikkelsen@gmail.com seawater buffer of an appropriate salinity. however, the calculated brine salinity would still be an average value, and would not take into account, for example, brine inclusions that may experience even higher salinities. osmotic stress can thus be decreased but not avoided when melting sea ice. direct melting will also expose the sea-ice algae to osmotic stress, but gives the advantage of performing all measurements on the same core, and decreases the risk of contamination. this study examines the effect of four melting procedures on the sea-ice algal community analysis: direct melting at 4 and 20°c, and melting in buffering seawater with salinities of 10 and 30. methods sea ice was sampled within an area of 1 m2 in kobbefjord, greenland, on 2 april 2008 (64°09.34′n, 51°25.18′w; fig. 1). light intensity (li-190sa quantum sensor; li-cor biosciences, lincoln, ne, usa), air temperature (testo 110 thermometer, testo, lenzkirch, germany) and snow thickness were determined at the onset of sampling. sea-ice cores were taken using an ice auger (mark iii; kovacs enterprises, lebanon, nh, usa). both the sea-ice thickness and the bottom sea-ice temperature were measured (testo 110 thermometer). the bottom 10 cm of the sea-ice cores were transported to the laboratory in polyethylene containers. the ice cores had a diameter of 7.25 cm, and the volume of each sample was approximately 413 cm3. the 12 sea-ice samples were melted in triplicate, as follows: (a) melted directly at 20°c; (b) melted directly at 4°c; (c) melted in 500 ml of artificial seawater (salinity of 10) at 4°c; (d) melted in 500 ml of artificial seawater (salinity of 30) at 4°c. the artificial seawater was made by dissolving 89.3 g nacl, 28.6 g mgso4 7h2o and 0.13 g nahco3 in 1000 ml of purified water (elga labwater, marlow, uk), and diluting to the appropriate salinity. all sea-ice samples were melted in the dark. the conductivity of melted sea ice was measured (orion 3-star with orion 013610md conductivity cell; thermo fisher scientific, waltham, ma, usa) and converted to salinity (grasshoff et al. 1983). sea-ice brine salinity was calculated as a function of temperature (cox & weeks 1983). a known volume of each sea-ice sample was filtered (<0.1 bar) using a glass microfibre filter with a diameter of 1.2 mm (grade gf/c glass microfibre filter; whatman, maidstone, kent, uk) for chlorophyll determination. chlorophyll was extracted in 96% ethanol for 18 h, and fluorescence was measured with a td-700 fluorometer (turner designs, sunnyvale, ca, usa). melted sea-ice samples were preserved in lugol’s solution (to a final concentration of 1%). for the taxonomic analysis and abundance calculation, melted sea-ice samples were studied by utermöhl’s (1958) method, using 25and 50-ml utermöhl chambers. analyses were performed with an inverted microscope (eclipse te300; nikon instruments, melville, ny, usa) equipped with 10¥ and 40¥ plan fluor objectives, and with a 60¥ (1.4 numerical aperture) plan apochromat oil immersion objective, all with differential interference contrast.the magnification of the ocular was 10¥. the mann–whitney u-test was applied to compare the melting methods one-on-one for the abundance and relative contribution of the identified taxa. results when sampling the sea ice, the surface irradiance was 665 mmol photons m–2 s–1 and the air temperature was fig. 1 kobbefjord, south-west greenland. the cross marks the sampling station and the dashed line marks the maximum sea-ice extent. ko bb ef jo rd nuuk x 3 km arct ic c ircl e melting sea ice for taxonomic analysis d.m. mikkelsen et al. polar research 29 2010 451–454 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd452 0.5°c. very little snow cover was present (<2 cm). the sea ice was 42–43 cm thick, with no slush ice and little snow cover (<5 cm). the bottom sea-ice temperature was stable from –0.5 to –0.6°c, corresponding to a brine salinity of 9–11 (cox & weeks 1983). the taxonomic analysis showed that the sea-ice community consisted of diatoms, cysts and flagellates (fig. 2). the relative contributions of diatoms, total flagellates and cysts were not significantly different (%; mann–whitney u-test). the most abundant diatom genera were nitzschia, thalassiosira, skeletonema, cylindrotheca, attheya, navicula, fragilariopsis and chaetoceros. the flagellate groups (fig. 3) encountered were chlorophytes (e.g., chlamydonomas), cryptophytes, chrysophytes (e.g., dinobryon) and dinoflagellates (including alexandrium, gymnodinium, amphidinium and prorocentrum), as well as some small unidentified flagellates. statistically significant variation among the melting procedures was apparent for most taxonomic groups, except diatoms and cryptophytes (table 1): melting procedure a (direct melting at 20°c) was statistically different to melting procedure b (direct melting at 4°c) for total flagellates, chlorophytes and unidentified flagellates; was statistically different to melting procedure c (buffered melting at a salinity of 10) for chrysophytes and dinoflagellates; and was statistically different to melting procedure d (buffered melting at a salinity of 30) for chlorophytes and chrysophytes. statistical variation between the other three melting procedures is observed only for chlorophytes, where melting procedure b (direct melting at 4°c) is statistically different to melting procedure c (buffered melting at a salinity of 10). the melting time of the melting procedures differed: melting procedure a (direct melting) took 0.6 of a day; melting procedure b (direct slow melting) took 4.5 days; and melting procedures c and d (buffered melting, regardless of salinity) took 3 days. discussion the sea-ice algal community consisted of diatoms, cysts and flagellates, with no significant difference in the relative composition (%), regardless of the melting procedure. however, regarding specific flagellate groups (chlorophytes, chrysophytes, dinoflagellates and unidentified flagellates), melting procedure a (direct melting at 20°c) was significantly different to one or more of the other melting procedures. the melting time varied from 0.6 to 4.5 days, depending on the melting procedure. the melting time is relevant as algal growth and death, as well as predation, may influence the composition of the sea-ice algal community. the primary productivity of sea-ice algae in kobbefjord has previously been quantified, ranging from <1 to 21 mg c m–2 d–1 (mikkelsen et al. 2008). in this study, samples from all melting procedures were melted in the dark to minimize the productivity of the sea-ice algae. with primary production minimized, there is an inherent risk that some algae will perish. in addition, predation may have an influence. predators in sea ice include heterotrophic dinoflagellates and ciliates. ciliates were observed, but in low abundance (data not shown), and the abundance of ciliates did not relate to the melting time (e.g., the ciliate abundance was similar in melting procedure a and d, which had melting times of 0.6 and 3 a dcb flagellates cysts diatoms 100 0 50 fig. 2 average taxonomic composition of the sea-ice algal community (%, n = 3): (a) direct melting (20°c); (b) direct melting (4°c); (c) buffered melting (salinity of 10); (d) buffered melting (salinity of 30). a dcb chrysophytes chlorophytes dinoflagellates cryptophytes 20000 0 10000 fig. 3 average taxonomic composition of the sea-ice algal community (%, n = 3): (a) direct melting (20°c); (b) direct melting (4°c); (c) buffered melting (salinity of 10); (d) buffered melting (salinity of 30). table 1 statistically significant difference (mann–whitney u-test, p = 0.05), based on abundance, between melting procedures: (a) direct melting (20°c); (b) direct melting (4°c); (c) buffered melting (salinity of 10); and (d) buffered melting (salinity of 30). significant difference diatoms — cysts — total flagellates a : b chlorophytes a : b, a : d, b : c cryptophytes — chrysophytes a : c, a : d dinoflagellates a : c unidentified flagellates a : b total algae — melting sea ice for taxonomic analysisd.m. mikkelsen et al. polar research 29 2010 451–454 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 453 days, respectively). overall, if the melting time had significantly impacted the taxonomic composition, the samples would have been grouped according to melting time, with melting procedure b differing from c and d. the results of the taxonomic analysis show that melting procedure b, c and d were significantly different to melting procedure a, but not to each other, and that the influence of melting time is therefore negligible within the time range encountered in this study. however, seaice algal communities may sustain a higher abundance of protozoa, and the effect of melting time could thus vary. a general recommendation on melting time based on this study is to melt the samples slowly (>1 day), but not too slowly (<1 week). the observed difference in taxonomic composition among melting procedures is observed for the following flagellate groups: chlorophytes, chrysophytes, dinoflagellates and unidentified flagellates. based on limited samples, it has previously been suggested that direct melting (at an unspecified temperature) differs from melting in buffered water (garrison & buck 1986). the effect of direct melting at 20°c on the sea-ice algal composition (this study) is presumably a consequence of flagellate cell lysis. this is supported by decreased abundance in samples melted by melting procedure a (fig. 3). as the sea-ice algal habitat undergoes large variations in salinity, it is likely that sea-ice algae exhibit increased halotolerance. some sea-ice algae are known to remain physiologically active at a salinity of 129 (stoecker et al. 1997), and might also be more tolerant to osmotic stress. osmotic acclimation can be achieved by a variety of mechanisms, such as changed concentration of organic osmolytes (e.g., proline), ion transport and adapted morphological features (reviewed by kirst 1989). the capability of sea-ice algae to adapt to osmotic stress if it is applied relatively slowly could explain the comparability of the “slow” melting procedures in this study (direct melting at 4°c and buffered melting). this study has shown that sea-ice algae do not undergo cell lysis as a result of osmotic stress during sea-ice melt if a slow melting procedure is applied. the definition of a slow melting procedure is not exact, but it is recommended that melting time should be measured in days. while direct melting at 20°c should be avoided, melting procedures such as direct melting at 4°c and buffered melting at salinities of 10 and 30 render the sea-ice algae comparable for taxonomic analysis. this means that a comparison of data from a wide geographic and historical range is possible, which will increase our knowledge of the sympagic algal communities. such a comparison, pooling existing data, would provide detailed background knowledge on the spatial, temporal and environmental patterns of sea-ice algal communities. however, for physiological measurements, the melting procedure remains important (e.g., ryan et al. 2004), and should be considered carefully. acknowledgements this project received funding from the danish energy agency as part of the climate support programme to the arctic. the work is a contribution to the zackenberg basic and nuuk basic programmes in greenland. references cox g.f.n. & weeks w.f. 1983. equations for determining the gas and brine volumes in sea-ice samples. journal of glaciology 29, 306–316. garrison d.l. & buck k.r. 1986. organism losses during ice melting: a serious bias in sea ice community studies. polar biology 6, 237–239. grasshoff k., erhardt m. & kremling k. 1983. methods of seawater analysis. weinheim, germany: verlag chemie. haecky p. & andersson a. 1999. primary and bacterial production in sea ice in the northern baltic sea. aquatic microbial ecology 20, 107–118. ikävalko j. 1998. further observations on flagellates within sea ice in northern bothnian bay, the baltic sea. polar biology 19, 323–329. kirst g.o. 1989. salinity tolerance of eukaryotic marine algae. annual review of plant physiology and plant molecular biology 40, 21–53. medlin l.k. & priddle j. 1990. polar marine diatoms. cambridge: british antarctic survey. mikkelsen d.m., rysgaard s. & glud r.n. 2008. microalgal composition and primary production in arctic sea ice—a seasonal study from kobbefjord/kangerluarsunnguaq, west greenland. marine ecology progress series 368, 65–74. ryan k.g., ralph p. & mcminn a. 2004. acclimation of antarctic bottom-ice algal communities to lowered salinities during melting. polar biology 27, 679–686. stoecker d.k., gustafson d.e., merrell j.r., black m.m.d. & baier c.t. 1997. excystment and growth of chrysophytes and dinoflagellates at low temperatures and high salinities in antarctic sea-ice. journal of phycology 33, 585–595. utermöhl h. 1958. phytoplankton methodik. (phytoplankton methodology.) mitteilungen der internationale vereinigung für theoretische und angewandte limnologie 9, 1–38. von quillfeldt c.h. 1996. ice algae and phytoplankton in north norwegian waters and arctic waters: species composition, succession and distribution. phd thesis, university of tromsø. melting sea ice for taxonomic analysis d.m. mikkelsen et al. polar research 29 2010 451–454 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd454 no job name post-moult distribution and abundance of white-fronted geese and canada geese in west greenland in 2007por_183 413..420 anthony d. fox1 & christian m. glahder2 1 department of wildlife ecology and biodiversity, national environmental research institute, aarhus university, kalø, grenåvej 14, dk-8410 rønde, denmark 2 department of arctic environment, national environmental research institute, aarhus university, po box 358, frederiksborgvej 399, dk-4000 roskilde, denmark abstract rapid increases in north american canada geese (branta canadensis) summering in west greenland since the mid-1980s compare with declines in the endemic population of white-fronted geese (anser albifrons flavirostris) nesting in the same region since 1999 (wintering in europe). to provide information on the distribution and abundance of the two species in greenland during the prelude to the autumn migration back to winter quarters, we here report on the first ever post-moult aerial surveys of west greenland between 64° and 73°n (from regular transects and transit reconnaissance flights in august 2007), which located 1888 greenland white-fronted geese and 6071 canada geese. strip transect surveys found 733 greenland white-fronted geese and 1318 canada geese in the 993 km2 surveyed, which, given a white-fronted goose global population of 23 200 in winter 2007/08, suggests more than 41 500 canada geese in west greenland post-moult in 2007. virtually no geese were found south of 66°n. the eqalummiut nunaat–nassuttuup nunaa and naternaq ramsar wetlands of international importance, and lowland disko island, saqqaqdalen and svartenhuk supported the highest densities of both species. results confirmed that areas important for both species during spring, nesting and moulting periods retain high densities of post-moulting geese. canada and white-fronted geese rarely occurred together within 2.5 km ¥ 400 m transect sectors, as found during breeding surveys. only in western svartenhuk and western disko were there canada goose concentrations that could potentially support an intensive autumn hunt, whilst avoiding disturbance to white-fronted geese. keywords aerial survey; anser albifrons flavirostris; autumn migration; branta canadensis; competition; immigration. correspondence anthony d. fox, department of wildlife ecology and biodiversity, national environmental research institute, aarhus university, kalø, grenåvej 14, dk-8410 rønde, denmark. e-mail: tfo@dmu.dk doi:10.1111/j.1751-8369.2010.00183.x agricultural monocultures of selectively bred cereals, root crops and highly nutritious grasses now dominate extensive areas of temperate europe and north america, providing artificial winter food to arctic-nesting geese (van eerden et al. 2005). as a result, many goose populations have expanded in abundance and range since the 1970s (e.g., madsen et al. 1999; abraham et al. 2005; van eerden et al. 2005), increasing overlap in time and space throughout the annual cycle, where allopatry was formerly common, and enhancing interspecific interactions (madsen et al. 1999). at specific bottlenecks in the annual cycle, unevenness in the ability to exploit limited resources may affect the distribution and abundance of one co-occuring species over another, and potentially affect fitness components (newton 1998; keddy 2001). behavioural dominance of one goose species over another sympatric species may affect feeding behaviour, distribution and/or access to favoured food items of the less dominant species, leading to local displacement. greater canada geese (branta canadensis) have colonized west greenland from north america, as a breeding species and moult migrant. a rare, but regular, breeding summer visitor before 1980, the species is now abundant between 66° and 70°n in west greenland (salomonsen 1981; boertmann 1994; fox et al. 1996; malecki et al. 2000). colonizers apparently originate from the north atlantic population (b. canadensis interior) breeding in northern quebec (scribner et al. 2003). ringing and polar research 29 2010 413–420 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 413 mailto:tfo@dmu.dk telemetry studies show that they migrate via labrador to winter along the atlantic seaboard of the usa (kristiansen et al. 1999; scribner et al. 2003). canada geese are behaviourally dominant over the endemic greenland white-fronted geese (anser albifrons flavirostris) during the flightless moult period when access to food becomes potentially limiting (kristiansen & jarrett 2002). the colonization of greenland by canada geese (with a mean adult body mass during moult of ca. 3.2 kg) wintering in atlantic coast north america could potentially affect the abundance of the smaller white-fronted geese (ca. 2.5 kg) wintering in western europe. although hard evidence for competition on a larger scale or in a way that may affect the reproductive output in the greenland white-fronted goose is lacking, it remains important to monitor the development of the canada goose population in west greenland. following the population expansion achieved under legislation protecting geese from winter hunting in ireland and the uk during the period 1982–1999, white-fronted geese summering in west greenland have declined from ca. 35 600 in 1999 to 23 200 individuals in 2008 (fox et al. 2006; fox et al. 2008). since 1999, low reproductive success has failed to replace annual mortality losses, although there is no consistent evidence that increasing interspecific competition or enhanced predation rates of nesting attempts have been behind the phenomenon. several explanations have been put forward to account for reductions in reproductive output, with most centred on the condition of females. elevated disease or parasite burdens seem unlikely (fox et al. 2006), but recent low reproductive output apparently correlates with the heavier spring snowfall (which delays reproduction) experienced since 1995 (boyd & fox 2008). the geographical distribution of both species was described prior to 1999 (fencker 1950; fox & stroud 1988; kristiansen et al. 1999). however, the relative densities throughout west greenland were unknown prior to the systematic aerial surveys of breeding pairs undertaken in 1999, and repeated in 2005 (malecki et al. 2000; fox & glahder unpubl. ms), which found the highest densities of both species between 66°55′n and 67°30′n, and found very few pairs further south and only locally in suitable habitat north of nuussuaq (70°30′n; see figs. 1, 2 for place names). neither species have been surveyed post-moult, when both species must deposit fat stores in preparation for autumn migration to winter quarters. for this reason, a late summer survey was undertaken in august 2007 to map the distribution and abundance of both species, to compare with midsummer nesting surveys, and to identify important goose areas during the post-moult and premigration period, and provide a baseline for comparisons with future surveillance programmes. an autumn canada goose hunt in west greenland may offer a harvestable resource as well as a potential means to limit numbers, should it be shown that the increase in this colonizing species is having a deleterious effect on the endemic whitefronted goose. hence, a secondary objective was to assess the degree of segregation of the two species with a view to the geographic potential for implementing a canada goose hunt without adverse effects on the native species. methods transects were flown at 200–230 km h-1 at 25–36 m above the ground using a specially adapted twin-engined partenavia observer aircraft, with a plexiglas dome for forward observations and bubble observation windows to either side. short sections of the survey transects were unavoidably flown at up to 120 m above ground level over difficult terrain. two observers seated (1) to the right of the pilot and (2) immediately behind him recorded all goose observations, as single birds, pairs or groups of individuals, and the perpendicular distance to the individual or cluster was measured using the angle of declination from the horizontal with a hand-held inclinometer. details were spoken onto a dictaphone tape with the precise observation time, which was synchronized with the clock on a gps that tracked the course of the aircraft for the survey duration, recording the position of the aircraft every 5 seconds. after transcription to a spreadsheet, timed events were converted to a latitude/ longitude position using a bespoke pascal program. declination angles for all observations were also converted geometrically to distance from the track line based on a flight altitude of 30 m, and entered on the database. we planned to correct our observations for the decreasing detectability of geese with distance using distance sampling software (thomas et al. 2006), but found little evidence of distance detection bias in the first 200 m from the observation platform, and effects out to 300 m were weak (as found elsewhere; certain & bretagnolle 2008). furthermore, because 1999 data were collected using a strip transect approach (counting all geese within the first 200 m of the aircraft and assuming complete detection within this area; buckland et al. 2001), the data we present here are based on all records within the first 200 m out from the track line for comparative treatment with the earlier surveys. we also used these data to compare the presence/absence of one or both species on the entire transect length and in 2.5-km lengths along each transect to test whether both species were more or less likely to occur together with each other than would be expected by chance at a local (2.5-km transect lengths) and larger (entire transect) scale using simple c2 contingency tables (after malecki et al. 2000). west greenland post-moult goose surveys a.d. fox & c.m. glahder polar research 29 2010 413–420 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd414 surveys were flown on 14, 15, 17, 18, 20 and 22 august 2007, covering areas 2, 3 and 4 (for survey areas covered in 1999, see malecki et al. 2000), under similar weather conditions, as well as part of area 1, covered in connection with an environmental assessment programme associated with the potential construction of an aluminium smelter in the area to the south (johansen et al. 2008). results overall numbers and distribution survey coverage and distribution of all canada and white-fronted geese are shown both on transect and during low-level transit flights in figs. 1 and 2. in all, 6071 canada geese and 1888 white-fronted geese were encountered, of which 1318 and 733, respectively, were within 200 m of the aircraft along 2483 km of transect lines flown. canada geese occurred in greatest numbers in svartenhuk (71°n), saqqaqdalen (southern nuussuaq, 70°n) and throughout disko island (69–70°n), but were also very common throughout the mainland south-east of disko island, in naternaq (68°n), and in the interior region closest to the ice cap south of naternaq, especially just north of kangerlussuaq, at ca. 67°n. white-fronted goose numbers were considerably sparser, with large numbers in eastern svartenhuk, a large group on ubekendt ejland and in saqqaqdalen, as well as lower densities in naternaq and the interior area south as far as just south 0 250 25 kmkm nn 1-8 9-22 23-38 39-71 72-270 no. observations survey track line transit line transect lakes ice cap land above 200 m land below 200 m kk sksk e n i 54°0'0"w 52°0'0"w 52°0'0"w 50°0'0"w 6 8 °0 '0 "n 6 8 °0 '0 "n 54°0'0"w 52°0'0"w 52°0'0"w 50°0'0"w 6 8 °0 '0 "n 6 8 °0 '0 "n (a) area 2 area 2a area 3 area 4 area 2 area 2a area 3 area 4 k sk e n i (b) fig. 1 map showing the distribution of encounters of all (a) white-fronted geese (anser albifrons flavirostris) and (b) canada geese (branta canadensis) during surveys undertaken in august 2007 between 66°15′ and 69°30′n in the west greenland study area. the transects used in the study, falling in areas 2 and 3, and part of area 4 (defined by red dotted lines), are as described by malecki et al. (2000). transect lines are marked in black; low-level transit flights where geese were encountered between transects are indicated in red. abbreviations indicate places named in the text, as follows: e, eqalummiut nunaat–nassuttuup nunaa; i, ilulissat; k, kangerlussuaq; n, naternaq; sk, northern fringe of the sukkertoppen ice cap. west greenland post-moult goose surveysa.d. fox & c.m. glahder polar research 29 2010 413–420 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 415 of kangerlussuaq. only 40 canada geese were seen south of 66°n (32 in a single flock during transit); no whitefronted geese were seen this far south, so data are not plotted here. distribution on transects the highest canada goose densities were encountered in area 2, especially from kangerlussuaq to eqalummiut nunaat (67–68°n), but densities were generally high (exceeding 1.25 birds km-2) in all survey areas except area 1 (table 1). densities of white-fronted geese were highest in area 4, where they were double those found elsewhere; none were present in area 1 (table 1). degree of association between the species occurrence of the two species differed significantly from the null hypothesis of complete association at the transect level (c2 = 5.41, df = 1, p < 0.05) and that of dissociation (c2 = 41.6, df = 1, p < 0.05). the distributions did not differ significantly from the null hypothesis of an even spread over transects where one or the other of the species occurred (c2 = 0.18, df = 1, p > 0.05). on the individual count unit level (2.5-km segments), the mutual occurrence of the two species differed significantly from that expected under the null hypothesis of association (c2 = 45.1, df = 1, p < 0.05) and of even distribution of the species where one or other occurs (c2 = 14.8, df = 1, 58°0'0"w 56°0'0"w 54°0'0"w 52°0'0"w 52°0'0"w54°0'0"w 50°0'0"w 7 2 °0 '0 "n 7 0 °0 '0 "n 7 2 °0 '0 "n 7 0 °0 '0 "n 58°0'0"w 56°0'0"w 54°0'0"w 52°0'0"w 52°0'0"w54°0'0"w 50°0'0"w 7 2 °0 '0 "n 7 0 °0 '0 "n 7 2 °0 '0 "n 7 0 °0 '0 "n nu up sv ub s d (b)(a) 0 250 25 kmkm nn 1-8 9-22 23-38 39-71 72-270 no. observations survey track line transit line transect lakes ice cap land above 200 m land below 200 m fig. 2 map showing the distribution of encounters of all (a) white-fronted geese (anser albifrons flavirostris) and (b) canada geese (branta canadensis) during surveys undertaken in august 2007 between 69°30′ and 72°54′n in the west greenland study area. all transects fall in area 4 as described by malecki et al. (2000). transect lines are marked in black; low-level transit flights where geese were encountered between transects are indicated in red. abbreviations indicate places named in the text as follows: d, disko island; nu, nuussuaq peninsula; s, saqqaqdalen; sv, svartenhuk; ub, ubekendt ejland; up, upernavik. west greenland post-moult goose surveys a.d. fox & c.m. glahder polar research 29 2010 413–420 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd416 p < 0.05), but there was no significant difference between the observed distributions and that expected if the species showed complete dissociation on this level (c2 = 0.0001, df = 1, p > 0.05). discussion after the wing moult, migratory geese must rapidly accumulate energy stores and potentially reconstruct body parts (such as heart and flight musculature) to migrate back to wintering quarters. greenland white-fronted geese must cross the greenland ice cap and open sea to stage in iceland on the 2000–3000 km autumn migration to ireland and the uk (fox et al. 2003). canada geese in west greenland migrate 3000–4000 km to winter in the eastern usa, from connecticut south to maryland (kristiansen et al. 1999). greenland white-fronted geese cross the ice cap and denmark strait, and canada geese cross davis strait, so neither can refuel on the first ca. 1500 and 1000 km, respectively. both populations require undisturbed access to energy rich food at this time, and knowledge of the extent and use of areas exploited is important to their future management. overall numbers and distribution both species were encountered in greater numbers than in the june surveys (malecki et al. 2000; fox & glahder, unpubl. ms), presumably as a result of greater aggregation into post-breeding flocks and less cryptic behaviour (compared with during nesting). we urge prudence in calculating goose densities from the transect data presented here because of the mobility of the geese at this time of year (unlike when pairs associate with nest sites in june), and the likelihood of differential detection probabilities of the two species may also affect measures of relative abundance on transect. nevertheless, the ratio of 1318:733 canada geese to white-fronted geese on transect potentially suggests there could be in excess of 41 500 canada geese in west greenland, given a global population of 23 200 greenland white-fronted geese in the region surveyed (based on winter 2007/08 census data [fox et al. 2008] and an equal probability of detecting both species). this is probably a conservative estimate, given the overall ratio of 6071:1888, including all transit flight observations, especially given the high august 2007 densities of canada geese encountered off transect on disko island, where white-fronted geese were relatively scarce. differences in distribution compared with other periods of the summer canada and white-fronted goose distributions closely resembled that of both species from june surveys ofta b le 1 s u m m ar y re su lt s fr o m th e 2 0 0 7 p o st -m o u lt in g ae ri al su rv e y o f g e e se in w e st g re e n la n d .n u m b e re d ar e as re fe r to th o se d e fin e d b y m al e ck ie t al .( 1 9 9 9 ), e xc lu d in g ar e a 2 a (s e e fi g . 1 ), w h ic h w as n o t co ve re d in th at su rv e y. c o lu m n s sh o w th e n u m b e r o f tr an se ct s flo w n in e ac h ar e a, th e d is ta n ce flo w n o n th e tr an se ct an d th e e ff e ct iv e ar e a co ve re d o u t to 2 0 0 m e it h e r si d e o f th e ai rc ra ft , an d th e n u m b e rs o f g e e se an d th e ir d e n si ty e n co u n te re d . c o lu m n s al so in d ic at e th e p e rc e n ta g e d is tr ib u ti o n o f th e to ta ls b e tw e e n th e fiv e ar e as . n u m b e r o f tr an se ct s fl o w n tr an se ct le n g th (k m ) to ta lc e n su s ar e a co ve re d (k m 2 ) to ta lw h it e -f ro n te d g e e se to ta lc an ad a g e e se % w h it e -f ro n te d g e e se in e ac h ar e a % c an ad a g e e se in e ac h ar e a w h it e -f ro n te d g o o se d e n si ti e s c an ad a g o o se d e n si ti e s a re a 1 1 1 6 4 0 .7 2 5 6 .3 0 8 0 0 .6 0 0 .0 3 a re a 2 a 3 3 3 8 .0 1 3 5 .2 1 1 8 1 7 2 1 6 .1 1 3 .1 0 .8 7 1 .2 7 a re a 2 4 2 6 0 .9 1 0 4 .3 7 3 3 2 6 1 0 .0 2 4 .7 0 .7 0 3 .1 2 a re a 3 9 9 1 6 .0 3 6 6 .4 3 2 7 6 1 9 4 4 .6 4 7 .0 0 .8 9 1 .6 9 a re a 4 1 4 3 2 7 .6 1 3 1 .0 2 1 5 1 9 3 2 9 .3 1 4 .6 1 .6 4 1 .4 7 to ta ls 4 1 2 4 8 3 9 9 3 7 3 3 1 3 1 8 1 0 0 .0 1 0 0 .0 0 .7 4 1 .3 3 west greenland post-moult goose surveysa.d. fox & c.m. glahder polar research 29 2010 413–420 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 417 breeding pairs (malecki et al. 2000; fox & glahder, unpubl. ms). areas south of nuuk were not surveyed (no geese were found here in 1999, and there have been no reports since malecki et al. 2000). coverage from the nordland peninsula north of nuuk fjord north to the southern edge of the sukkertoppen ice cap at 66°n found only two groups of canada geese during 4 hours 18 minutes of transect and transit survey. much of the northern section from 65° to 66°n suffers late spring lie, and is of relatively high altitude, with sparse vegetation and little attraction for feeding geese. nordland peninsula is richly vegetated and superficially looks attractive to geese, but experiences late snow cover in spring, and as in earlier surveys, supported no geese in 2007. the highest canada goose densities were found inland from kangerlussuaq (67°n) north to naternaq and ilulissat, which experiences a continental climate because of the geoclimatic effects of the proximity of the inland ice. this area hosts the highest breeding white-fronted goose densities (malecki et al. 2000; fox & stroud 2002), although this species occurred out to the coast during the august 2007 survey, where canada geese were absent (fig. 2). large numbers of canada geese were seen in naternaq and surrounding lowland areas out to the coast, where lesser numbers of white-fronted geese were also present. both eqalummiut nunaat–nassuttuup nunaa (5000 km2) and naternaq (1500 km2) are protected as ramsar sites for their importance for summering white-fronted geese. very few geese of either species were found on the mainland east of disko island, confirming earlier observations from spring staging, nesting and moulting surveys, but dense concentrations of canada geese were present in disko island lowlands (with fewer white-fronted geese). goose densities were high in saqqaqdalen, but low in the central valley of nuussuaq where large moulting concentrations, formerly of white-fronted geese (glahder 1999) and latterly of canada geese, have been reported (boertmann 2004). the lack of geese here in august 2007 could result from a lack of suitable heathy, berry-bearing vegetation to support feeding geese post-moult, or could be a consequence of active mining exploration in summer 2007, especially at the western end where the fewest geese were seen. large concentrations of canada geese occurred in the lowland svartenhuk peninsula, with large numbers of white-fronted geese on the eastern side. few canada geese were encountered north of svartenhuk during a brief reconnaissance of lowland areas south of upernavik. this pattern confirms areas previously identified as important for white-fronted geese during spring, nesting and moult periods, hold high post-moult densities of these and canada geese, suggesting no major redistribution after the fledging of the young and the moult of the adults (fox & stroud 2002). the current extent of ramsar sites therefore effectively covers the main areas used by post-moulting geese, but parts of svartenhuk, disko, saqqaqdalen and nuussuaq peninsula (known to hold significant concentrations of geese at other times in summer) should be surveyed for the designation of further areas that qualify for ramsar designation on the strength of moult and post-moulting concentrations that exceed international importance. habitat considerations although impossible to determine habitat use from the air, geese move onto heaths in late summer post-moult to feed on vaccinium uliginosum berries (which grow on dry, sunny, well-drained soils) and especially empetrum hermaphroditum fruit (which is often dominant or co-dominant on north-facing moss-rich slopes and late snow beds). white-fronted geese shot near kangerlussuaq contained abundant berries in the oesophagus and crop in late august and early september (a. reenberg, pers. comm.). it seems likely that post-moult, greenland white-fronted geese switch to other habitats within the same summer range (namely berry-rich heaths) rather than moving between geographical areas post moult. this may not be the case where white-fronted geese were encountered between 67° and 68°n out towards the coast, in areas where this species has not been reported during earlier surveys, although they were reported doing so at the time of salomonsen (1950). generally, survey results suggested that canada geese are distributed in a similar way, selecting similar areas to the indigenous white-fronted geese, which they now dominate numerically in west greenland. densities were especially high in the interior between 67° and 69°n, but the species was abundant everywhere where suitable goose habitat existed. degree of association between the species canada and white-fronted geese were distributed evenly throughout the flown areas, but rarely occurred together when distributions were analysed by 2.5 km ¥ 400 m transect lengths, confirming segregation (potentially mutual avoidance) on a very local scale, as detected during both previous summer nesting surveys. the effect was insufficient to create single species concentrations that offered potential for an autumn canada goose hunt, whilst avoiding disturbance to white-fronted geese. nevertheless, fig. 1 shows that in areas of western svartenhuk and on the west side of disko island, canada geese aggregate in large flocks where few white-fronted geese were encountered. this suggests the possibility of west greenland post-moult goose surveys a.d. fox & c.m. glahder polar research 29 2010 413–420 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd418 hunting canada geese in these areas without adversely affecting the other species in these areas. another august survey of these two areas should be undertaken to verify this situation before such a hunt can be recommended. these surveys also provide an important baseline for future comparisons given the rapid increases in canada geese since the mid-1980s, compared with the unfavourable conservation status of the greenland white-fronted goose since 1999. acknowledgements we are extremely grateful to our pilot leif petersen for his outstanding skill in navigating and flying our transects low over difficult terrain. thanks to the danish polar centre and greenland home rule authority for granting permissions to carry out the surveys, and particularly to the danish environmental protection agency for their financial support of the project management of goose populations in west greenland (dancea project no. 127/001-0163). enormous thanks to ib krag petersen for gps support for managing the gis database, and to him and tinna christensen for producing the maps presented here, min huang for insight and information on the status of the north atlantic population (nap) of canada geese and to all the many counters who provide monitoring data from the winter quarters used in the article. references abraham k., jefferies r.l. & alisauskas r.t. 2005. the dynamics of landscape change and snow geese in mid-continent north america. global change biology 11, 841–855. boertmann d. 1994. an annotated checklist to the birds of greenland. meddelelser om grønland, bioscience 38. copenhagen: commission for scientific research in greenland. boertmann d. 2004. background studies in nuussuaq and disko, west greenland. report 482. roskilde, denmark: national environmental research institute. boyd h. & fox a.d. 2008. effects of climate change on the breeding success of white-fronted geese anser albifrons flavirostris in west greenland. wildfowl 58, 55–70. buckland s.t., anderson d.r., burnham k.p., laake j. l., borchers d.l. & thomas l. 2001. introduction to distance sampling. estimating abundance of biological populations. oxford: university press. certain g. & bretagnolle v. 2008. monitoring seabirds population in marine ecosystem: the use of strip-transect aerial surveys. remote sensing of the environment 112, 3314–3322. fencker h. 1950. den grønlandske blisgås anser albifrons flavirostris og dens ynglebiologi. (the greenland white-fronted goose anser albifrons flavirostris and its breeding biology.) dansk ornitologisk forenings tidsskrift 44, 61–65. (in danish with english summary.) fox a.d., francis i.s. & walsh a.j. 2008. report of the 2007/8 international census of greenland white-fronted geese. rønde, denmark: greenland white-fronted goose study. wexford, ireland: national parks and wildlife service. fox a.d., glahder c., mitchell c., stroud d.a., boyd h. & frikke j. 1996. north american canada geese (branta canadensis) in west greenland. auk 113, 231–233. fox a.d., glahder c.m. & walsh a.j. 2003. spring migration routes and timing of greenland white-fronted geese—results from satellite telemetry. oikos 103, 415–425. fox a.d. & stroud d.a. 1988. the breeding biology of the greenland white-fronted goose anser albifrons flavirostris. meddelelser om grønland, bioscience 27. copenhagen: commission for scientific research in greenland. fox a.d. & stroud d.a. 2002. greenland white-fronted goose. bwp update 4, 65–88. fox a.d., stroud d.a., walsh a.j., wilson h.j., norriss d.w. & francis i.s. 2006. the rise and fall of the greenland white-fronted goose: a case study in international conservation. british birds 99, 242–261. glahder c.m. 1999. sensitive areas and periods of the greenland white-fronted goose in west greenland. spring staging and moult as important bottleneck periods in the annual cycle of the goose species. roskilde, denmark: national environmental research institute. johansen p., aastrup p., boertmann d., glahder c., johansen k., nymand j., rasmussen l.m. & tamstorf m. 2008. aluminiumsmelter og vandkraft i det centrale vestgrønland. technical report 664. roskilde, denmark: national environmental research institute, aarhus university. (in danish with english summary.) keddy p.a. 2001. competition. dordrecht: kluwer. kristiansen j.n., fox a.d. & jarrett n.s. 1999. resightings and recoveries of canada geese branta canadensis ringed in west greenland. wildfowl 50, 199–203. kristiansen j.n. & jarrett n.s. 2002. inter-specific competition between greenland white-fronted geese anser albifrons flavirostris and canada geese branta canadensis interior moulting in west greenland: mechanisms and consequences. ardea 90, 1–13. madsen j., cracknell g. & fox a.d. (eds.) 1999. goose populations of the western palearctic. a review of status and distribution. wetlands international publication 48. wageningen, the netherlands: wetlands international/ rønde, denmark: national environmental research institute. malecki r.a., fox a.d. & batt b.d.j. 2000. an aerial survey of nesting white-fronted and canada geese in west greenland. wildfowl 51, 49–58. newton i. 1998. population limitation in birds. london: academic press. salomonsen f. 1950. the birds of greenland. copenhagen: munksgaard. west greenland post-moult goose surveysa.d. fox & c.m. glahder polar research 29 2010 413–420 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 419 salomonsen f. 1981. fugle. (birds.) pp. 159–361. in m. muus et al. (eds.): grønlands fauna (greenland’s fauna). copenhagen: gyldendal. scribner k.t., malecki r.a., batt b.d.j., inman r.l., libants s. & prince h.h. 2003. identification of source population for greenland canada geese: genetic assessment of a recent colonization. condor 105, 771–782. thomas l., laake j.l., strindberg s., marques f.f.c., buckland s.t., borchers d.l., anderson d.r., burnham k.p., hedley s.l., pollard j.h., bishop j.r.b. & marques t.a. 2006. distance 5.0. release 1. st. andrews: research unit for wildlife population assessment, university of st. andrews. van eerden m.r., drent r.h., stahl j. & bakker j.p. 2005. connecting seas: western palaearctic continental flyway for water birds in the perspective of changing land use and climate. global change biology 11, 894–908. west greenland post-moult goose surveys a.d. fox & c.m. glahder polar research 29 2010 413–420 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd420 por_031.fm polar research 26 2007 207 – 208 © 2007 the author 207 b o o k r e v i e w review of the cryosphere and global environmental change , by olav slaymaker & richard e.j. kelly (2007). malden, ma: blackwell publishing. 261 pp. isbn 1-4051-2976-x. there is no shortage of books on climate change. however, despite the work of the intergovernmental panel on climate change and the arctic climate impact assessment, we still know surprisingly little about the impact of global environmental change processes (not just climate change) on the broad range of biophysical and sociocultural systems that operate in the cryosphere. this lack of understanding prompts the authors to ask whether the global community cares about the future of the cryosphere, and the people who live within it. justifying their work by pointing out the interconnectedness of the cryosphere with other components of the earth, and discussing ongoing policy debates, geographers olav slaymaker and richard kelly aim to inform international debates on global change, in the broadest sense. this is the first in a series of books on environmental systems and global change, edited by professor anthony orme, and published by blackwell. the series arises from the merger of blackwell’s “environmental systems” and pearson’s “understanding global environmental change” series. intended to be multidisciplinary or interdisciplinary, and to show how environmental systems operate, interact and respond to change over different scales of time and space, the books are also intended to be relevant to international social and environmental challenges. the target audience is advanced undergraduates and graduate students from a wide range of disciplines, but especially physical geography, earth science and environmental science. this series is timely, in my view. scholars within the subdiscipline of physical geography have increasingly been expressing their frustration at their isolation from the mainstream of their discipline (e.g. gregory 2001). some key concerns have included the lack of theoretical frameworks and irrelevance to the human side of the discipline. however, these concerns certainly do not apply to this book, which is not only a contribution to our understanding of environmental change in the cryosphere, but is also a step forward in the development and implementation of a much needed new paradigm for physical geography. olav slaymaker, professor of geography at the university of british columbia, made his reputation in mountain geomorphology and hydrology. however, he has also worked with distinction for many years on land use impacts, sustainable development and global environmental change in mountain environments. co-author richard kelly, associate professor of geography at the university of waterloo in ontario, is an expert in remote sensing of snow and ice. together, their backgrounds provide the needed breadth of experience and expertise to write a book of this scope. taking a comprehensive and integrated view of the cryosphere, slaymaker and kelly consider sedimentary, geomorphic and landscape systems of areas affected by ice sheets, sea ice, snow, river and lake ice, glaciers and permafrost. the authors marshal evidence of the processes, timing and causes of change, and invoke theories derived from geomorphology, ecology and social science to interpret those changes in terms correspondence department of geography, okanagan college, kelowna, british columbia, canada. e-mail: tday@okanagan.bc.ca 208 polar research 26 2007 207 – 208 © 2007 the author book review of what the authors call “cryosphere transience and transitional landscapes”. drivers and resistance to change are examined in an attempt to account for transience of facies, landforms and landscapes. the book signals a major advance in our thinking on environmental change in the cryosphere, by initiating discussion on theoretical approaches to cryosphere transience. slaymaker & kelly’s main focus is on buzz holling’s panarchy theory as a framework for understanding this change (holling 2001). originally developed to explain ecosystem response to disturbance, holling’s ideas are applied here in a broader system context. although panarchy is a complex theory, the essence is that ecosystems go through a series of stages which holling depicts as a loop. the initial steps in the process involve a dominant species accumulating biomass, capital and wealth. however, if conditions change then there is creative destruction and reorganization in the system backloop. the result is that biomass, capital and wealth is released to create irreversible and often unpredictable change to the system. holling stresses that system interdependence means that changes in one system will also have implications for adjacent systems, including all biophysical, social and economic systems. therefore, slaymaker & kelly also make connections to geomorphic theory (especially brunsden 1990), and the work of jared diamond (2005). the models are deployed in a broad conceptual manner. together with data on quaternary cryosphere change discussed earlier in the book, slaymaker & kelly use the models to suggest that punctuated change is the norm. the models link biological and physical factors with socioeconomic and cultural changes in such a way as to emphasize the two-way causality and interdependence of humankind with its environment. they also face squarely the historical and contemporary evidence that sociological systems collapse: some reorganize themselves creatively whereas others disappear. if punctuated change is the norm, then the notion of sustainability as stability must be questioned: is it even possible to reconcile the concept of global cryospheric change . . . with the idea of sustainability? the concept of sustainability seems to ignore the phenomena of transience, of transitional states, and the collapse of the cryosphere. (p. 202) slaymaker & kelly conclude with some important questions. expanding on their question about whether the global community cares about the cryosphere and the people who live within it, the authors ask in the book’s conclusion, “how much ‘collapse’ can be absorbed and how much of the ‘transience’ can be accommodated to allow an orderly and ethical transition?” (p. 224). hopefully, answers will be provided for such questions before they become irrelevant. the book is for the most part well written. with firstrate illustrations and up-to-date references, the initial chapters provide an excellent synthesis of environmental change in the cryosphere. although i would have liked to have seen a more thorough description and discussion of the theory in the final chapters, the book makes important contributions that deserve to be widely read and discussed. terence day department of geography, okanagan college, kelowna, british columbia, canada references brunsden d. 1990. tablets of stone: toward the ten commandments of geomorphology. zeitschrift für geomorphologie supplementband 79 , 1–37. diamond j. 2005. collapse: how societies choose to fail or succeed . london: penguin books. gregory k.j. 2001. changing the nature of physical geography. fennia 179 , 9–19. holling c.s. 2001. understanding the complexity of economic, ecological and social systems. ecosystems 4 , 390–405. no job name colonization of the polar willow salix polaris on the early stage of succession after glacier retreat in the high arctic, ny-ålesund, svalbardpor_170 385..390 takayuki nakatsubo,1 masaaki fujiyoshi,2 shinpei yoshitake,3 hiroshi koizumi4 & masaki uchida5 1 graduate school of biosphere science, hiroshima university, higashi-hiroshima, 739-8521, japan 2 school of humanities and culture, tokai university, kitakaname 1117, hiratsuka, 259-1292, japan 3 graduate school of advanced science and engineering, waseda university, 2-2, wakamatsucho, shinjuku-ku, tokyo, 162-8480, japan 4 faculty of education and integrated arts and sciences, waseda university, 2-2, wakamatsucho, shinjuku-ku, tokyo, 162-8480, japan 5 national institute of polar research, 10-3, midori-cho, tachikawa city, tokyo 190-8518, japan abstract the polar willow (salix polaris), predominant in the late successional stage in deglaciated areas of ny-ålesund, svalbard, is rarely found in the early stage, when purple saxifrage (saxifraga oppositifolia) dominates. to elucidate the pattern and the mechanism of successional change from the saxifraga stage to the salix stage, we examined the distribution pattern, size structure and habitat conditions of a colonizing salix population in the seral stage where salix was invading saxifraga-dominated sites. the present distribution pattern and aerial photographs taken in the past suggest that salix colonization at this site commenced within the last 70 years. we found 115 salix individuals (22 male, 13 female and 80 unknown) in a 30 m ¥ 30 m quadrat on the seral stage. although the largest individual had a size of 2000 cm2 (length ¥ maximum width), the majority (84%) of individuals were smaller than 100 cm2. the seedling size distribution, as inferred from the leaf scar number, indicated that annual recruitment was slight. of the individuals observed about 75% had colonized bare ground; only four individuals grew within saxifraga colonies. no significant difference was found in soil characteristics (water content, and carbon and nitrogen concentrations) between the seral stage and the earlier stage prior to colonization by salix. these results suggest that difficulties in seed production, germination and/or seedling establishment of salix, rather than soil formation by preceding species (saxifraga), limits the early-stage colonization by salix. keywords glacier retreat; high arctic; population structure; salix polaris; succession; svalbard. correspondence takayuki nakatsubo, graduate school of biosphere science, hiroshima university, higashi-hiroshima, 739-8521, japan. e-mail: kuyakat@hiroshima-u.ac.jp doi:10.1111/j.1751-8369.2010.00170.x glacier retreat is occurring widely in the arctic, including the high arctic (green 2005; kohler et al. 2007). some evidence suggests that many glaciers in western svalbard are losing mass at an increasing rate (kohler et al. 2007). glacier retreat provides new habitats for plant colonization, where organic matter accumulates. information related to colonization rates of plants, especially dominant species, and their limiting factors is critically important for predicting how ecosystems in deglaciated areas will respond to future climate change. in a deglaciated area in ny-ålesund, svalbard, purple saxifrage (saxifraga oppositifolia l.) colonizes bare ground as early as a few years after deglaciation (kume et al. 1999). several traits enable this species to be the first colonizer in the area: high fecundity, the ability to form adventitious roots from shoot fragments (kume et al. 1999) and low leaf nitrogen content, which might facilitate their establishment on nutrient-poor substrates (muraoka et al. 2008). in addition, saxifraga oppositifolia is known to have two growth forms—prostrate and semierect—that are adapted to maximize growth in different habitat conditions (crawford et al. 1995). in contrast, the polar willow (salix polaris wahlenb.), a dwarf shrub with creeping subterranean shoots or polar research 29 2010 385–390 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 385 mailto:kuyakat@hiroshima-u.ac.jp occurring in a moss carpet, predominates in the late successional stage, but it is rarely found in the early stage, where saxifraga oppositifolia dominates (kume et al. 1999; nakatsubo et al. 1998; nakatsubo et al. 2005; muraoka et al. 2008). this species has high leaf photosynthetic capacity, and plays a crucial role in carbon sequestration in the deglaciated ground (muraoka et al. 2002). muraoka et al. (2008) estimated that the contribution of salix polaris is as high as 12 times that of the pioneer plant saxifraga oppositifolia. therefore, invasion by salix polaris during the early stage is important not only in terms of community structure but also for carbon sequestration in this area. to date, however, the pattern and the mechanism of the successional change from the saxifraga stage to the salix stage have been undocumented. this study specifically examined the seral stage–– between the early and the late successional stages–– during which salix polaris colonizes saxifraga-dominated sites. we examined the distribution pattern, size structure and habitat conditions of colonizing salix populations in the seral stage to study the colonization rate of salix and its limiting factor(s). materials and methods the study site was situated in the glacier foreland of austre brøggerbreen, near ny-ålesund, on the fjord kongsfjorden in svalbard (78.5°n, 11.5°e). in the kongsfjorden area, the retreat rates of glaciers ending on land are reportedly about 10–20 m per year (svendsen et al. 2002). the rate of retreat of austre brøggerbreen determined in our field study agrees with these values: the recession was about 30 m between 2003 and 2005, and about 60 m between 2003 and 2008. the annual mean air temperature and precipitation in this area between 2001 and 2008 were, respectively, -4.2°c and 433 mm. the ground begins to be free of snow in early july; snow begins to accumulate in mid-september. several authors have studied the vegetation and succession pattern in the glacier foreland of austre brøggerbreen (nakatsubo et al. 2005; ohtsuka et al. 2006), and of a neighbouring glacier (hodkinson et al. 2003). saxifraga oppositifolia is the most common pioneer plant in the newly deglaciated moraines of austre brøggerbreen, although it also occurs in later stages. late stages are dominated by various species, including mosses, such as sanionia uncinata (hedw.) loeske and aulacomnium turgidum (wahlenb.) schwaegr., and vascular plants, such as saxifraga oppositifolia, salix polaris, dryas octopetala l. and luzula confusa lindeb. the early stage (saxifraga stage) and the later stages of succession are divided spatially by the floodplain (fig. 1). a recent study (nakatsubo et al. 2008) showed that part of the later stage had developed on a raised beach deposit. although salix was rare in the early stage, colonization of scattered individuals of salix was observed in the old part (near the floodplain) of the early stage. this stage is hereafter designated as the “seral stage”. early in august 2008, a 30 m ¥ 30 m quadrat (quadrat a) was set in the seral stage. the distance between quadrat a and the front of the austre brøggerbreen glacier was about 1 km. for comparison, another 30 m ¥ 30 m quadrat (quadrat b), within which no salix was observed, was set in the upper (more recently deglaciated) site of the deglaciated area. 1000 m a b 1977 1936 fp fp 2008 fig. 1 satellite image showing the study site in the glacier foreland of austre brøggerbreen, near ny-ålesund, svalbard. locations of the two quadrats (a and b), the glacier front terminus in 1936 and 1977, and the floodplain (fp) are also shown; they were determined using aerial photographs from the norwegian polar institute. colonization of polar willow after glacier retreat t. nakatsubo et al. polar research 29 2010 385–390 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd386 the two quadrats were situated in the middle of the two lateral moraines (west and east ridges) of austre brøggerbreen (fig. 1). the respective vegetation coverage ratios (mainly saxifraga oppositifolia) of quadrats a and b were about 3 and <1%, respectively. accurate positions of these quadrats were determined using a portable gps receiver (trimble geoxt gps unit; trimble navigation, ca, usa) and a satellite image (advanced land observing satellite multi-spectral advanced visible near infrared 2 sensor image, acquired on 31 july 2008). aerial photographs from the norwegian polar institute were used to demarcate successive changes visually at the glacier front terminus in 1936 and 1977. the quadrats were subdivided into 5 m ¥ 5 m subquadrats, and the size, sex and position of each salix plant within the subquadrat was recorded. because the salix colony shape varied widely, the length (l) and the maximum width (w) of the ground covered by each colony was measured: l ¥ w was used as the plant size index. a preliminary study indicated that there was a highly significant relationship between the index (l ¥ w) and the colony size (area) determined from photographs with an image scanner (r = 0.99; p < 0.001). the sex of each (male, female or unknown) was determined according to inflorescence. seed production in female inflorescences of the current (2008) and previous year (2007) were also recorded. individuals smaller than 1 cm2 were recorded as “seedlings”. to determine the seedling age, we collected all seedlings and counted leaf scars under a binocular microscope. at that time, the presence of mycorrhiza was also recorded. we examined the relation of salix polaris to saxifraga oppositifolia colonies. each salix individual was classified into one of the following three categories based on its position relative to saxifraga: (1) salix colony growing within the saxifraga colony; (2) salix colony growing close to saxifraga (with at least one branch of the two species crossed); (3) salix colony colonizing bare ground. to examine the study site soil characteristics, soil samples of the 0–3 cm layer were collected from 18 randomly selected subquadrats in each quadrat. fresh weights of these samples were measured to obtain their water contents later. they were freeze-dried and brought back to japan. the total carbon and nitrogen contents of the soil were measured using a cn analyser (sumigraph nc-22; sumika chemical analysis co., tokyo, japan). results and discussion colonization of salix polaris on the seral stage was observed only within 200 m of the riverbank. although five isolated individuals of salix were found between the two quadrats (a and b), we were unable to find any salix individual between quadrat b and the glacier front. the aerial photograph taken in 1936 showed that the glacier front was near the riverbank; the study site was covered entirely by the glacier at that time. by 1977, when another photograph was taken, the site was left exposed by the glacier (fig. 1). although the site might have been subjected to disturbances after deglaciation, these data suggest that colonization of salix commenced within the last 70 years. this rapidity of colonization is faster than some late successional species in other glacier forelands, e.g., betula nana in a glacier foreland in mainland norway (whittaker 1993). however, although saxifraga oppositifolia invaded near to the glacier front, salix colonization was limited to the older part of the moraine, which suggests that the salix invasion speed is insufficient to keep up with the recession speed, which was estimated as about 10–20 m annually (svendsen et al. 2002). this pattern of colonization of salix polaris and saxifraga oppositifolia in our study site is somewhat different from that reported for the neighbouring glacier, midre lovénbreeen (hodkinson et al. 2003), where isolated small seedlings of salix were found in a pioneer site of as young as 2 years (hodkinson et al. 2003). however, successional changes in frequency of occurrence and in ground cover were slower in salix than in saxifraga (hodkinson et al. 2003: figs. 2, 3), which also suggests a limited ability of salix to colonize pioneer sites. in quadrat a we found 115 salix individuals (22 male, 13 female and 80 unknown, including seedlings), although the total coverage of salix was less than 1%. the largest individual was 2000 cm2 (l ¥ w), but most (84%) of the individuals were smaller than 100 cm2 (fig. 2a). the size structure of the colonizing population (fig. 2a) resembles an inverted j-shaped size distribution: a population structure with a relatively constant juvenile supply (mori et al. 2006). however, the fraction of individuals larger than 100 cm2 was very small, and the size distribution of the large individuals is discontinuous. moreover, analysis of leaf scars revealed that the age of the small individuals classified as seedlings varied widely, ranging from less than 5 years to greater than 20 years (figs. 2b, 3). half of the seedlings had more than five leaf scars. because most seedlings had two or three green leaves, it is estimated that most seedlings were older than several years. these results indicate that annual recruitment was quite limited: not more than 10 individuals in the 30 m ¥ 30 m quadrat. regarding propagation by seeds, vegetative propagation might play some role in salix colonization. reportedly, salix polaris can form roots from shoot fragments, but this capability is rather limited compared with colonization of polar willow after glacier retreatt. nakatsubo et al. polar research 29 2010 385–390 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 387 that of saxifraga oppositifolia with its prostrate growth form, which has high rhizogenesis ability and which spreads vegetatively by shoot fragments (kume et al. 1999). apparently, the short above-ground part of salix is unsuitable for propagation by shoot fragments. in fact, we were unable to find any rooted fragments of salix in our study site. this difference in vegetative propagation might partly explain why salix is rare in the early stage, and why saxifraga oppositifolia dominates. several factors might explain the small annual recruitment of salix polaris at this study site. seed availability can be a limiting factor of plant colonization in this area. cooper et al. (2004), who examined the composition and density of soil seed banks in svalbard, reported that salix polaris is common in vegetation, but was a poor germinator in seed bank trials. at our study site, seven of the 13 females failed to bear seeds in 2008 (table 1), suggesting the difficulty in seed set in this area. additionally, we were unable to find even a single seedling around some female plants (table 2), which suggests limited germination and/or high seedling mortality in the field. slow initial growth rate, as indicated by the analysis of leaf scars (figs 2b, 3), might also contribute to the slow colonization of salix at this site. it has been suggested that facilitation, the process by which colonizing species improve the environment for later successional species, is among the major successional mechanisms in severe environments (chapin et al. fig. 2 size distribution of the salix polaris population at the study site. (a) the size distribution of salix individuals found in quadrat a (n = 115). sizes are expressed as the product of the length (l) and the maximum width (w) of the colony. (b) the size distribution of seedlings based on the number of leaf scars, excluding cotyledons. 0 20 40 60 80 100 120 -9 9 1 0 0 -1 9 9 2 0 0 -2 9 9 3 0 0 -3 9 9 4 0 0 -4 9 9 5 0 0 -5 9 9 6 0 0 -6 9 9 7 0 0 -7 9 9 8 0 0 -8 9 9 9 0 0 size class (cm2 ) n u m b e r o f p la n ts female male unknown (a) 0 2 4 6 8 10 12 0-4 5-8 9-12 13-16 17-20 21-24 25< number of leaf scars + green leaves n u m b e r o f se e d lin g s (b) 10 mm c s c s m s s c c m m m m s fig. 3 salix seedlings of different ages: s, leaf scar; c, cotyledon or its leaf scar; m, mycorrhizal roots. colonization of polar willow after glacier retreat t. nakatsubo et al. polar research 29 2010 385–390 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd388 1994). if this applies to our study site, it is expected that the late successional species (salix) colonizes sites where the early successional species (saxifraga) has already been established. our results did not support this hypothesis: about 75% of salix individuals had colonized bare ground, although only four individuals grew within saxifraga colonies (table 2). this difference indicates that the presence of the preceding species is unimportant, at least for the initial stage of salix colonization. furthermore, no significant difference was found in soil characteristics (water content, and carbon and nitrogen concentrations) between the seral stage (quadrat a) and the saxifraga stage (quadrat b) (student’s t-test, p > 0.05) (table 3). we also examined the correlation between soil characteristics (water content, and carbon and nitrogen concentrations) and the number of salix individuals in the subquadrats of quadrat a. the relation was not found to be significant (n = 18, p > 0.05). therefore, it is unlikely that colonization of salix was limited by soil development in our study site. another factor that might have affected the colonization of salix is the presence of mycorrhizal fungi. reportedly, colonization of mycorrhizal fungi facilitates subsequent seedling establishment of salix species in a successional volcanic desert (nara & hogetsu 2004). at this study site, all salix seedlings had ecotomycorrhiza. it is likely that whether the seedling was able to form a mycorrhizal association determined the survival of the seedling. this hypothesis should be tested through future study, including culture experiments. to conclude, salix polaris is a later colonizer of the deglaciated area than the pioneer saxifraga oppositifolia. however, the presence of the preceding species— saxifraga—is not a prerequisite of salix colonization. the slight annual recruitment, which might be explained by low seed availability, difficulties in germination and/or seedling establishment, has limited the colonization rate of salix at this study site. the colonization rate is insufficient to keep up with the speed of the glacier’s recession. the loss of the glacier in this region has accelerated in recent years, in response to climate change (nuth et al. 2007). therefore, it is unlikely that salix will make an important contribution to carbon sequestration in newly exposed sites unless future climate change considerably raises its colonization rate. acknowledgements the authors wish to thank dr kenlo nishida nasahara of the university of tsukuba and the japan aerospace exploration agency for operating the advanced land observing “daichi” satellite. this study was supported by a grant-in-aid for scientific research by the japan society for the promotion of science. references chapin f.s. iii, walker l.r., fastie c.l. & sharman l.c. 1994. mechanisms of primary succession following deglaciation at glacier bay, alaska. ecological monographs 64, 149–175. cooper e.j., alsos i.g., hagen d., smith f.m., coulson s.j. & hodkinson i.d. 2004. plant recruitment in the high arctic: seed bank and seedling emergence on svalbard. journal of vegetation science 15, 115–224. crawford r.m.m., chapman h.m. & smith l.c. 1995. adaptation to variation in growing season length in arctic population of saxifraga oppositifolia l. botanical journal of scotland 47, 177–192. green a.m. 2005. a time constant for hemispheric glacier mass balance. journal of glaciology 51, 353–362. table 1 seed production of each female salix polaris plant. individual females seed production presence of seedlings around the femalea2007 2008 1 + + + 2 + + + 3 + + + 4 + + 5 + + 6 + 7 + + 8 + 9 + + 10 + + + 11 + 12 + 13 + a distance from the female to each seedling was less than 1 m. table 2 colonizing site of salix polaris in relation to saxifraga oppositifolia within the 30 m ¥ 30 m quadrat. colonizing site number of salix individuals within a saxifraga colony 4 close to saxifragaa 25 bare ground 86 a with at least one branch of the two species crossed. table 3 some soil characteristics of the two 30 m ¥ 30 m quadrats. mean values of soil samples (0–3 cm depth) collected from 18 randomly selected subquadrats (5 m ¥ 5 m) are shown with the sd. soil characteristics quadrat a quadrat b water contenta 0.15 � 0.06 0.15 � 0.06 carbon concentration (%) 0.56 � 0.21 0.48 � 0.17 nitrogen concentration (%) 0.03 � 0.01 0.03 � 0.01 a water content = (fresh weight – dry weight)/dry weight. colonization of polar willow after glacier retreatt. nakatsubo et al. polar research 29 2010 385–390 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 389 hodkinson i.d., coulson s.j. & webb n.r. 2003. community assembly along proglacial chronosequences in the high arctic: vegetation and soil development in north-west svalbard. journal of ecology 91, 651–663. kohler j., james t.d., murray t., nuth c., brandt o., barrand n.e., aas h.f. & luckman a. 2007. acceleration in thinning rate on western svalbard glaciers. geophysical research letters 34, l18502, doi: 10.1029/2007gl030681. kume a., nakatsubo t., bekku y. & masuzawa t. 1999. ecological significance of different growth forms of purple saxifrage, saxifraga oppositifolia l., in the high arctic, ny-ålesund, svalbard. arctic, antarctic, and alpine research 31, 27–33. mori a., osono t., iwasaki s., uchida m. and kanda h. 2006. initial recruitment and establishment of vascular plants in relation to topographical variation in microsite conditions on a recently-deglaciated moraine on ellesmere island, high arctic canada. polar bioscience 19, 85–95. muraoka h., noda h., uchida m., ohtsuka t., koizumi h. & nakatsubo t. 2008. photosynthetic characteristics and biomass distribution of the dominant vascular plant species in a high arctic tundra ecosystem, ny-ålesund, svalbard: implications for their role in ecosystem carbon gain. journal of plant research 121, 137–145. muraoka h., uchida m., mishio m., nakatsubo t., kanda h. & koizumi h. 2002. leaf photosynthetic characteristics and net primary production of the polar willow (salix polaris) in a high arctic polar semi-desert, ny-ålesund, svalbard. canadian journal of botany 80, 1193–1202. nakatsubo t., bekku y., kume a. & koizumi h. 1998. respiration of the belowground parts of vascular plants: its contribution to total soil respiration on a successional glacier foreland in ny-ålesund, svalbard. polar research 17, 53–59. nakatsubo t., bekku y.s., uchida m., muraoka h., kume a., ohtsuka t., masuzawa t., kanda h. & koizumi h. 2005. ecosystem development and carbon cycle on a glacier foreland in the high arctic, ny-ålesund, svalbard. journal of plant research 118, 173–179. nakatsubo t., yoshitake s., uchida m., uchida m., shibata y. & koizumi h. 2008. organic carbon and microbial biomass in a raised beach deposit under terrestrial vegetation in the high arctic, ny-ålesund, svalbard. polar research 27, 23–27. nara k. & hogetsu t. 2004. ectomycorrhizal fungi on established shrubs facilitate subsequent seedling establishment of successional plant species. ecology 85, 1700–1707. nuth c., kohler j., aas h.f., brandt o. & hagen j.o. 2007. glacier geometry and elevation changes on svalbard (1936–90): a baseline dataset. annals of glaciology 46, 106–116. ohtsuka t., adachi m., uchida m. & nakatsubo t. 2006. relationships between vegetation types and soil properties along a topographical gradient on the northern coast of the brøgger peninsula, svalbard. polar bioscience 19, 63–72. svendsen h., beszczynska-møller a., hagen j.o., lefauconnier b., tverberg v., gerland s., ørbæk j.b., bischof k., papucci c., zajaczkowski m., azzolini r., bruland o., wiencke c., winther j.-g. & dallmann w. 2002. the physical environment of kongsfjorden– krossfjorden, an arctic fjord system in svalbard. polar research 21, 133–166. whittaker r.j. 1993. plant population patterns in a glacier foreland succession: pioneer herbs and later-colonizing shrubs. ecography 16, 117–136. colonization of polar willow after glacier retreat t. nakatsubo et al. polar research 29 2010 385–390 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd390 por_032.fm polar research 26 2007 91 – 92 © 2007 the author 91 from the editor—world environment day 2007 doi:10.1111/j.1751-8369.2007.00032.x commemorated every year on 5 june, world environment day (wed) was established by the united nations in 1972 to help stimulate worldwide awareness of the environment and to enhance political engagement in environmental issues. although the day is marked around the world, the united nations environment programme selects one city to host the main wed celebrations, which are focussed on a central theme encapsulated in a slogan. past wed host cities have included algiers (”don’t desert dry lands“), san francisco (“green cities—plan for the planet”), barcelona (“wanted! seas and oceans—dead or alive?”) and beirut (“water—two billion people are dying for it”). this year the honour was bestowed on tromsø, norway, and the theme of climate change was expressed in the slogan: “melting ice—a hot topic?”. a youth film festival, an international children’s art competition, a concert, an ecumenical church service and an international conference on climate change are just some of the many diverse activities that took place in tromsø over the course of several days to commemorate the wed. the conference took place at the university of tromsø and was organized by the norwegian polar institute and the norwegian ministry of the environment, with the support of the ministry for foreign affairs and the nordic norwegian prime minister jens stoltenberg addresses the melting ice conference. the seated panel are, from left to right: igor tsjestin, secretary general of the world wide fund for nature in russia; sheila watt cloutier, former president of the inuit circumpolar conference; masoumeh ebtekar, head of the centre for peace and environment in iran; achim steiner, executive director of the united nations environment programme; archbishop desmond tutu; and erik solheim, norwegian minister of development. (photo by s. gerland, courtesy of the norwegian polar institute picture library.) 92 polar research 26 2007 91 – 92 © 2007 the author from the editor council of ministers. the first session commemorated the 20th anniversary of the report our common future , issued by the world commission on environment and development under the leadership of gro harlem brundtland (who has also served as prime minister of norway and director-general of the world health organization). gro harlem brundtland, who is now a united nations special envoy on climate change, and rajendra pachauri, chairman of the intergovernmental panel on climate change, delivered the conference’s keynote addresses to an audience that included high-level statesmen and prominent environmental and human rights activists, indigenous peoples’ representatives and scientists from around the world. many contributed presentations themselves during the two-day event, creating a stimulating mix of political, humanistic and scientific viewpoints. four of the talks given at the conference are reproduced in the following pages, some very close to the form in which they were originally given and others somewhat modified. these pieces should give the reader a sense of the broad scope of the conference. achim steiner, executive director of the un environment programme, focussed on policy and how it is informed by climate change science. biologist philip wookey considered arctic biodiversity, and the physician henning pedersen discussed human health issues. geologist/photographer hinrich bäsemann touched on many of these topics with his captivating photographic essay, which, regrettably, had to be pared down for publication here because of space constraints. this issue also includes—as promised in the last issue of polar research —an article by historian stian bones tracing norway’s involvement in past international polar years. helle v. goldman chief editor doi:10.3402/polar.v33.19986 r e s e a r c h / r e v i e w a r t i c l e the impact of seabirds on the content of various forms of phosphorus in organic soils of the bellsund coast, western spitsbergen marta ziółek1 & jerzy melke2 1 department of environmental protection, faculty of earth sciences and spatial management, maria curie-skłodowska university, al. kraśnicka 2cd, pl-20-718, lublin, poland 2 department of soil science and soil protection, faculty of earth sciences and spatial management, maria curie-skłodowska university, al. kraśnicka 2cd, pl-20-718 lublin, poland keywords phosphorus fractions; organic soils; seabirds; nutrient enrichment; spitsbergen. correspondence marta ziółek, department of environmental protection, al. kraśnicka 2cd, pl-20-718 lublin, poland. e-mail: marta.ziolek@ poczta.umcs.lublin.pl abstract in areas isolated from direct human impact, such as spitsbergen, environmental changes result mainly from natural processes, which include nutrient enrichment caused by seabirds. the objective of this study was to evaluate the degree of nutrient enrichment of organic soils fertilized by seabirds, indicated by the phosphorus content and transformations. this study encompassed two areas on the bellsund coast. a profile without the influence of seabirds and profiles located at different distances from the colony of birds (0�150 m) were analysed. a sequential phosphorus fractionation method was used, and three inorganic p (pi) fractions were obtained as a result: pi-l (labile p), pi-feal (p associated with fe and al) and pi-camg (p associated with ca and mg); and two fractions of organic p (po): po-huac (p associated with humic acids) and po-res (residual p). polar organic soils not subjected to the direct seabird impact contained amounts of total phosphorus (pt) similar to organic soils in other climate zones. the presence of the seabird colony increased the pt content and changed the distribution between the ratio of organic and inorganic p fractions. within the inorganic p fraction, the pi�camg component was dominant and its distribution was modified by the fertilizing effect of bird droppings. the nutrient enrichment of organic soils by birds in the polar zone was therefore very strong. the transformations affecting the soil environment of svalbard result mainly from natural processes on account of the archipelago’s remote location. spitsbergen’s soil cover has formed differently than the soil cover of southerly locations, primarily due to its climate and the impact of glaciers. the present soil cover of spitsbergen has been influenced by humidity, weathering and cryogenic processes in addition to the relief and lithology of the bedrock (forman & miller 1984; mann et al. 1986; klimowicz & uziak 1988; uziak 1992; blümel et al. 1993; klimowicz et al. 1993; melke & chodorowski 2006; klimowicz et al. 2008). in very humid tundra, vegetation develops in local depressions of coastal plains or on hill slopes and at the foot of the slopes. the formation of peat soils in these habitats is significantly influenced by seabird colonies that increase the nutrient content in the soils in the coastal zone. many species of birds foraging in the sea deliver large quantities of faeces rich in macroand micro-elements directly to the soils in the neighbourhood of their breeding sites (speir & cowling 1984; tatur 1989, 2002; godzik 1991; headley 1996; anderson & polis 1999; ligęza & smal 2003; hawke & newman 2004). thus, the seabirds directly influence the chemical properties of the soils forming there and, indirectly, the vegetation cover (hogg & morton 1983; myrcha & tatur 1991; mun 1997; breuning-madsen et al. 2008; mulder et al. 2011). polar research 2014. # 2014 marta ziółek & jerzy melke. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 organic and organic-mineral soils are quite common in the bellsund area, but they occupy small areas associated with water stagnation and the presence of animals. peat soil profiles are usually shallow, rarely exceeding 50 cm (eurola 1971; zelikson 1971; låg 1980; göttlich & hornburg 1982; klimowicz et al. 1997). the chemical composition of organic soils on spitsbergen has not been well researched; only a few publications mention it (dobrovolsky 1990; jóźwik & magierski 1992; klimowicz et al. 1997; melke 1999). the literature also lacks studies mentioning the content of various forms of phosphorus and their mutual relationships in the organic soils of the arctic area. these data can be obtained by means of phosphorus speciation analysis. such studies focus on using various patterns of sequential phosphorus fractionation in order to examine the resources and transformations of phosphorus quantitatively and qualitatively (bedrock et al. 1994; cross & schlesinger 1995, 2001; ivanoff et al. 1998; robinson et al. 1998; schlichting et al. 2002; litaor et al. 2004; condron & newman 2011). phosphorus is an essential nutrient for plants because of the role it plays in biochemical processes. its deficiency in soil and water environments is a factor that limits primary production, and its excess leads to eutrophication of ecosystems (smil 2000; elser et al. 2007). hence, it determines the fertility of water and land ecosystems. it is relatively stable in the soil, and its secondary accumulation occurs in organic deposits (dowding et al. 1981; richardson & marshall 1986; craft & richardson 1993; wang et al. 2012). the determination of total phosphorus (pt) content as well as the content of its particular forms can help identify fertility changes taking place in the environment. the objective of this research was to study the content of various forms of phosphorus in organic soils subjected to the varying impacts of the seabirds; determine the distribution of various forms of p in the bulk p pool; and to identify the relationship between the inorganic and organic forms of phosphorus along with their location in the soil profiles. on that basis, an attempt was made to assess the impact of the seabirds on the nutrient enrichment of the soils in the immediate vicinity of a breeding colony. study area the study included two sites located at the southern shore of bellsund, in the north-western part of wedel jarlsberg land in western spitsbergen (fig. 1). the first site was a reference profile of organic soil not subjected to the direct impact of the seabirds, referred to as the skilvika profile. it is located within calypsostranda, on the skilvika bay near a seashore cliff (fig. 1). the site lies within a system of raised coastal terraces whose topographic surface reaches 40�65 m a.s.l. the area where peat occurs is a flat plain dissected by polygons of varying sizes, covered by various moss species and, to a lesser extent, by grass clumps and willow shrubs (salix polaris). the other site was the dunderdalen transect, located on the southern slope of dundrabeisen, at 30�90 m a.s.l. (fig. 1). a peat bog of the slope type occurs here, a short distance away from the sea coast, within a talus fan. above the peat bog, there is a nearly vertical cliff, devoid of vegetation but having hundreds of seabird nests, inhabited mostly by the black-legged kittiwake (rissa tridactyla). the peat bog under study is small in size (well below 1 ha), not more than 100 m in width; its inclination is about 308. the entire peat bog is overgrown by various moss species. materials and methods the skilvika profile was collected from a crevice filled with mossy peat. such crevices are usually 40�80 cm wide and more than 50 cm deep. permafrost lies below. the site where the material was collected had similar dimensions and lay on a flat surface fed by precipitation. the peat, along with the mineral substrate, was extracted to a depth of 67 cm and divided into 27 samples (1.5�2.5 cm thick; the mineral substrate sample was 7 cm thick). the material in the dunderdalen area was collected at seven points along a transect from the rock cliff to the foot of the slope (fig. 2). the first point was a surface sample located immediately underneath the seabird nests, composed of dry plant remains, bird droppings and feathers. points from 2 to 7 were soil samples, where the distance between points was about 25 m. the last point of transect was 150 m away from the seabird colony. the thickness of the organic horizon varied, but generally did not exceed 0.5 m. the organic horizon was underlain by rock debris of varying degrees of fragmentation. sampling locations 2�7 consisted of two or three samples (5 or 10 cm thick). a total of 15 samples were obtained from the entire transect. for the soil samples collected, a morphological description was prepared (tables 1, 2). after drying and grinding the material, the following were determined: hygroscopic water using the oven-drying method; organic matter and mineral ingredient content using the incandescence method (sapek & sapek 1997); carbonate content using the scheibler method (lityński et al. 1976); and ph in 0.01 m cacl2 using the potentiometric method (thomas 1996). the impact of seabirds on phosphorus in organic soils m. ziółek & j. melke 2 (page number not for citation purpose) citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 phosphorus fractionation was carried out for all samples from the dunderdalen transect and from 13 samples from the skilvika profile (selected according to the morphology and basic properties). there is a great variety of methods for determining various forms of phosphorus in mineral soils (cross & schlesinger 1995). based on these methods, modifications for organic soils have been developed. one of them is a modification by reddy et al. (1998) based on the chang & jackson method (1957). this sequential phosphorus fractioning method is widely used in american studies for soils in boggy areas (ivanoff et al. 1998; reddy et al. 1998; ann et al. 2000). its scheme is presented in fig. 3. the particular phosphorus fractions were determined by means of the ascorbic acid procedure of murphy & riley (kuo 1996), on a lambda 12 spectrophotometer (perkin elmer, waltham, ma, usa). the total inorganic phosphorus (pi) was calculated as the sum of the following fractions: labile, easily soluble phosphorus (pi�l), phosphorus associated with fe and al (pi�feal), and inorganic phosphorus associated with ca and mg (pi�camg). the total organic phosphorus (po) is the sum of the phosphorus associated with humic acids (po�huac) and phosphorus in residue fractions (po� res). the sum of all forms of phosphorus determined is referred to as pt. fig. 2 the location of sample collection points at the dunderdalen transect. fig. 1 location of the study area and survey points. (map based on zagórski 2005.) m. ziółek & j. melke the impact of seabirds on phosphorus in organic soils citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 table 1 basic properties and phosphorus sequential extract ion for the skilvika profile. om ph pi pi/pt po po/pt pt sample no. depth (cm) morphology/description of the deposits % cacl2 mg/kg % mg/kg % mg/kg po/pi 1 0�2 very little decomposed mossy peat; visible plant 86.4 6.7 393.2 43.7 506.1 56.3 899.3 1.3 3 4�5.5 remains*mainly moss, intertwined with living roots; 80.4 6.5 206.9 20.7 794.2 79.3 1001.0 3.8 5 7.0�8.5 light brown 58.0 6.5 247.9 20.4 968.0 79.6 1215.9 3.9 7 10.0�12.5 little to medium decomposed mossy peat; extent of plant 41.4 6.3 277.6 24.1 875.8 75.9 1153.4 3.1 9 15.0�17.5 remains decomposition increasing with depth; dark grey, 39.1 6.3 316.7 27.4 839.7 72.6 1156.4 2.6 10 17.5�20.0 darker in the bottom part 40.1 6.3 319.0 25.9 911.1 74.1 1230.1 2.9 13 25.0�27.5 37.2 6.5 338.5 32.4 705.2 67.6 1043.7 2.1. 16 32.5�35.0 33.2 6.4 378.7 37.5 629.8 62.5 1008.5 1.7 19 40.0�42.5 31.9 6.4 385.4 35.9 686.8 64.1 1072.2 1.8 22 47.5�50.0 well decomposed mossy peat without visible plant remains; 32.6 6.4 403.5 27.7 1054.1 72.3 1457.6 2.6 24 52.5�55.0 dark brown, nearly black 33.3 6.4 398.4 33.0 809.8 67.0 1208.1 2.0 25 55.0�57.5 28.3 6.4 402.5 36.5 700.3 63.5 1102.8 1.7 27 60.0�67.0 medium clay; grey�brown 10.4 6.4 462.5 41.4 655.7 58.6 1118.2 1.4 table 2 basic properties and phosphorus sequential extraction for the dunderdalen transect. sample profile depth om ph pi pi/pt po po/pt pt no. no. (cm) morphology/description of the deposits % cacl2 mg/kg % mg/kg % mg/kg po/pi 1 1 surface sample surface sample, organic, composed of dry plant remains, bird droppings and feathers 69.4 7.5 14908.4 92.3 1248.6 7.7 16157.0 0.1 2 2 0�10 little decomposed mossy peat; numerous visible plant remains*mainly moss, large contribution of dry plant remains; grey�brown 62.4 5.6 8279.0 83.6 1628.9 16.4 9907.9 0.2 3 2 10�20 little decomposed mossy peat; numerous visible plant remains; light brown 50.3 5.6 9089.7 84.2 1707.4 15.8 10797.1 0.2 4 3 0�10 medium decomposed mossy peat; visible small plant remains; dark brown�brown 76.6 6.3 3803.1 74.1 1328.8 25.9 5131.9 0.3 5 3 10�20 medium decomposed mossy peat; visible small plant remains; dark brown�brown 59.6 6.4 929.5 44.1 1175.8 55.8 2105.4 1.3 6 4 0�10 medium decomposed mossy pea; visible small plant remains; light brown 66.6 6.4. 975.6 45.0 1193.2 55.0 2168.9 1.2 7 4 15�25 well decomposed mossy peat; visible small plant remains; extent of plant remains decomposition increasing with depth; dark brown 67.7 6.9 1311.7 48.0 1420.4 52.0 2732.2 1.1 8 5 0�10 medium decomposed mossy peat; visible small plant remains; grey�brown 66.9 6.7 4584.0 77.2 1350.9 22.8 5934.9 0.3 9 5 10�20 well decomposed mossy peat; visible small plant remains; extent of plant remains decomposition increasing with depth; dark brown 30.5 7.0 1372.2 46.4 1587.3 53.6 2959.5 1.2 10 6 0�5 very little decomposed mossy peat; numerous visible plant remains*mainly moss; light brown 78.3 6.3 286.1 24.1 903.3 75.9 1189.5 3.2 11 6 5�10 medium decomposed mossy peat; extent of plant remains decomposition increasing with depth; dark brown�brown 75.5 6.5 332.4 24.9 1004.1 75.1 1336.5 3.0 12 6 15�25 well decomposed mossy peat; few plant remains; dark brown, nearly black 54.4 7.0 735.8 44.4 921.7 55.6 1657.5 1.2 13 7 0�5 medium decomposed mossy peat; few visible plant remains, intertwined with living roots; grey�brown 70.0 6.6 1101.8 41.1 1577.0 58.9 2678.9 1.4 14 7 5�15 medium decomposed mossy peat; extent of plant remains decomposition increasing with depth; grey�brown 47.5 6.5 1343.1 45.5 1607.2 54.5 2950.3 1.2 15 7 20�25 well decomposed mossy peat; few plant remains; grey�brown 31.7 6.8 1277.5 51.0 1227.2 49.0 2504.7 1.0 the impact of seabirds on phosphorus in organic soils m. ziółek & j. melke 4 (page number not for citation purpose) citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 results soil characteristics the basic physicochemical properties of the organic soils under study were variable, which resulted from the varying morphological structure, organic matter content and ash content. the organic part of the skilvika profile (mossy peat of varying degrees of decomposition) reached a depth of 57.5 cm (table 1). it was underlain by a clayey mineral substrate. the organic matter content in the surface part exceeded 80% and decreased with depth. the ph of the studied soil was slightly acidic (with the exception of neutral ph in the sample surface). in the dunderdalen peat transect, all the studied samples were organic (organic matter content ranged from 30.5 to 78.3%) overlying rock debris (table 2). the surface samples (0�10 or 0�5 cm in the remaining six sample locations) had a greater organic matter content than those lying deeper. the ph of the studied organic deposits ranged from slightly acidic to basic. the highest ph (7.5) was exhibited by a surface sample located immediately underneath the seabird colony, whereas the lowest ph (5.6) was represented by a sample from the neighbouring point 2. on both sites, the studied deposits did not contain carbonates. total p: content and distribution the soils of the sites under study were characterized by a high pt content which varied considerably between the two sites (tables 1, 2). very large quantities of pt were determined in the dunderdalen transect (from 1189.5 to 16157.0 mg/kg of dry matter); the greatest quantities occurred in points closest to the breeding seabird colony; these quantities fell as the distance from the colony increased (table 2). much lower and less varied pt content (from 899.3 to 1457.6 mg/kg of dry matter) was found in the skilvika profile (table 1). the smallest quantities were found in surface samples and they increased with depth. distribution of average values of p forms figure 4 compares the averaged values for all measured p forms from the dunderdalen transect against the reference of averaged values for all measured p forms from the silvika profile. average values of p for dunderdalen transect were calculated from all samples for all points (depth of 0�20 or 0�25 cm). average values for skilvika were obtained from surface samples with corresponding depth (0�20 cm; fig. 4). generally, the content of all p forms in the entire dunderdalen transect were higher than values obtained for the skilvika. it means that the fertilizing impact of the bird colony covered 150 m of transect and may have reached even further because of the steep slope. the highest values of pi�l, pi�feal, pi�camg, po�res forms and, accordingly, pt, occurred near the seabird colony (points 1 and 2 of the transect); they decreased in distance away from it, as shown by a regression line. the po�huac form was an exception as its values increased in distance away from the seabird colony. calculated determination coefficient r 2 showed that the correlation between the distance from the colony and p contents for the three p forms was strong (r 2 above 0.6). for the rest of the forms there was a weaker correlation between the distance from the colony and p contents (r 2 between 0.4 and 0.5; fig. 4). although the analysis was done for only seven sampling locations, for most of the forms the correlation is explicit. proportion of various phosphorus forms in the pt inorganic phosphorus*labile. the contribution of the pi�l (easily soluble) fraction in pt varied in the organic soils studied (table 3). for samples from the dunderdalen transect, the contribution ranged from 2.8 to 34.4%, whereas for the skilvika profile it ranged from 0.03 to 29.7% (figs. 5, 6). in dunderdalen, this fraction had the highest contribution in the surface sample below the seabird colony (more than 34%). in the other points of the transect, the percentage contribution of this form was lower, reaching maximum values (about 10%) in surface samples (fig. 6). in the skilvika profile, the maximum contribution of the pi�l fraction also occurred in the surface sample (nearly 30%), and it decreased rapidly with depth (to less than 1%; fig. 5). fig. 3 scheme used to determine the phosphorus fraction, developed by reddy et al. 1998 (ziółek 2007). m. ziółek & j. melke the impact of seabirds on phosphorus in organic soils citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 inorganic phosphorus associated with iron and aluminium. the contribution of the pi�feal fraction to the pt was low, and minor variation occurred between sites (table 3). in the skilvika profile this contribution ranged from 4.4 to 10.4% of pt, reaching the highest value in the surface sample (fig. 5). for the dunderdalen transect, the range was from 3.7 to 22.2% of pt, with a higher contribution in samples from the last point of the transect, and in the surface sample from below the seabird colony (fig. 6). inorganic phosphorus associated with calcium and magnesium. the percentage contribution and distribution of the pi�camg fraction varied considerably between the two sites (table 3). the contribution of this phosphorus form in the skilvika profile ranged from pi-l pi-camg po-huac ptpo-res pi-feai 6000 3000 2500 2000 1500 1000 500 5000 4000 p = 0.09 r2 = 0.47 p = 0.14 r2 = 0.39 p = 0.02 r2 = 0.71 p = 0.03 r2 = 0.66 p = 0.02 r2 = 0.67 p = 0.07 r2 = 0.50 3000 2000 1000 7000 6000 5000 4000 3000 2000 1000 1000 800 600 400 200 0 0 0 1200 1000 800 600 400 200 0 18000 15000 12000 9000 6000 3000 0 0 0 25 25 50 m g /k g m g /k g m g /k g m g /k g m g /k g m g /k g 100 125 150 m75 0 25 50 100 125 150 m75 50 100 125 150 m75 0 25 contents of various p forms in dunderdalen transect r2 determination coefficient p-value calculated for 95% confidence intervalskilvika reference site regression line for dependency between distance and p content 50 100 125 150 m75 0 25 50 100 125 150 m75 0 p 25 50 100 125 150 m75 fig. 4 averaged values of p forms for the dunderdalen transect plotted against silvika reference values. the impact of seabirds on phosphorus in organic soils m. ziółek & j. melke 6 (page number not for citation purpose) citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 3.6 to 36.6% of pt, and its distribution was characterized by values that increased with depth (fig. 5). in the dunderdalen transect, the pi�camg fraction was found to have a considerably greater contribution in the pt pool, ranging from 7.1 to 68.5% (fig. 6). the distribution of this form of phosphorus along the transect varied, and was different than in the skilvika profile; the highest values were found in the samples close to the seabird colony. this form dominated in the total p in points 1, 2 and 3 of the transect. total inorganic phosphorus. in the organic soils under study, pi accounted for 20.4�92.3% of the pt pool (tables 1, 2). the greatest contribution of pi, ranging from 24.1 to 92.3% of pt was found in samples from the dunderdalen transect (table 2). the highest values of inorganic forms occurred in the surface sample underneath the seabird colony (�92%) and in the samples in point 2 (�83%). in the skilvika profile, the contribution of pi forms was smaller and ranged from 20.4 to 43.7% of pt (table 1). pi had the highest percentage contribution in the surface sample and the sample from the mineral substrate. pi�camg was the dominant fraction in the total pi in both sites under study: up to 68.5% of the pi pool in the dunderdalen transect, and up to 36.6% of the pi pool in the skilvika profile (figs. 5, 6). the labile form of phosphorus, pi�l, also played a significant role in pi. organic phosphorus associated with humic acids (humic and fulvic). the organic form po� huac content varied considerably in the organic soils under study (table 3). this fraction had very high percentage contributions in the entire skilvika profile, ranging from 45.9 to 62.0% of pt (fig. 5). in the dunderdalen transect samples, the contribution of the po�huac form in the pt pool was lower and more varied, ranging from 2.8 to 54.1% (fig. 6). the lowest values of this form occurred near the seabird colony where they increased along the transect. table 3 skilvika profile and dunderdalen transect. the mean and standard deviation (sd) for the percentage contribution of different p forms in the total p pool. p fractions a mean (%) sd skilvika pi�l 3.1 8.3 pi�feal 6.9 1.6 pi�camg 21.3 9.3 po�huac 52.3 4.3 po�res 16.4 6.0 dunderdalen pi�l 9.9 7.3 pi�feal 9.5 6.6 pi�camg 35.6 21.4 po�huac 27.7 16.0 po�res 17.2 7.0 a terms are abbreviated as follows: labile inorganic p (pi�l); inorganic p bound with fe and al (pi�feal); inorganic p bound with ca and mg (pi�camg); organic p associated with humus acids (po�huac); residual organic p (po�res). fig. 5 skilvika profile. proportional participation of different forms of soil p in the total p pool. terms are abbreviated as follows: labile inorganic p (pi�l); inorganic p bound with fe and al (pi�feal); inorganic p bound with ca and mg (pi�camg); organic p associated with humus acids (po�huac); and residual organic p (po�res). m. ziółek & j. melke the impact of seabirds on phosphorus in organic soils citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 organic phosphorus in residue. po content in residue showed a very similar range of values for both sites: for the skilvika profile they ranged from 6.4 to 27.4% of pt, whereas for the dunderdalen transect they ranged from 4.9 to 28.0% of pt (figs. 5, 6, table 3). in the skilvika profile, the lowest values, below 10%, occurred in the surface sample and the deepest mineral sample, whereas the maximum values occurred in the upper part of the profile (7�12.5 cm). in the dunderdalen transect, the lowest percentage contribution of the po� res fraction occurred near the seabird colony. total organic phosphorus. in the skilvika profile, the po pool ranged from 56.3 to 79.6% of pt; its contribution was quite high and evenly spread throughout the profile (table 1). in the dunderdalen transect, po content varied considerably: from 7.7 to 75.9% of pt (table 2). the lowest value of po occurred in the upper part of the transect, close to the seabird colony. the po�huac fraction dominated among the po forms in the soils of spitsbergen (with the exception of the beginning of the dunderdalen transect, where the po�res form had a greater contribution). po/pi ratio. the ratio of the po to pi quantities was low for the soil in the dunderdalen transect fertilized by seabirds, reaching the lowest values near the seabird colony (from 0.1 to 1.3) (table 2). in the skilvika profile, not subjected to the direct impact of seabirds, the po/pi ratio was considerably higher (from 1.3 to 3.9; table 1). discussion the organic deposits under study were characterized by high pt content relative to values reported by other authors for different areas of the world (parent & khiari 2003). these values were considerably higher than values found for mineral soils, suggesting that the capacity of organic soils to take in and absorb phosphorus is greater than that of mineral soils (craft & richardson 1993; reddy et al. 1998; wang et al. 2012). there are also studies showing poor retention of p by organic soils (hawke & newman 2004). the phosphorus content and its distribution in organic soils are closely linked to the overlapping or joint effect of various factors and phenomena occurring during the development of these soils. the highest concentrations of phosphorus occurred directly below the seabird colony, indicating that seabirds have a crucial impact on the content of phosphorus in soils. the gregarious seabirds foraging in the sea fertilize soils close to their breeding grounds with large quantities of seabird droppings rich in phosphorus compounds (godzik 1991; myrcha & tatur 1991; klimowicz et al. 1997; anderson & polis 1999; ligęza & smal 2003; breuning-madsen et al. 2008). phosphorus delivered with seabird droppings are poorly soluble, accumulating fig. 6 dunderdalen transect. proportional participation of different forms of soil p in total p pool. terms are abbreviated as follows: labile inorganic p (pi�l); inorganic p bound with fe and al (pi�feal); inorganic p bound with ca and mg (pi�camg); organic p associated with humus acids (po�huac); and residual organic p (po�res). the impact of seabirds on phosphorus in organic soils m. ziółek & j. melke 8 (page number not for citation purpose) citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 intensively in the soil (comerford 1998). however, despite their relatively high capacity to accumulate p, organic soils cannot retain all of the large quantity of p delivered by seabirds, resulting in pt dispersion. this is demonstrated by a steady decrease in pt along the transect (fig. 4). at the skilvika site, which was not subject to the direct impact of seabirds, the pt quantities recorded were similar to those characteristic of subalpine peat bogs (wang et al. 2012) as well as organic soils of moderate climate zones not subjected to strong anthropogenic fertilization (ziółek 2007). an examination of the distribution of pt at dunderdalen showed that as one moved away from the seabird colony along the slope, phosphorus content decreased approximately by a factor of 8 (at points 3, 4 and 7 of the transect; table 2). the fertilization of the soil by seabird droppings in the dunderdalen transect was the strongest near the seabird nests, where intensive direct accumulation occurred, and decreased with the distance away from the seabird colony. the decrease in pt content along the slope with a considerable inclination could also result from the gradual accumulation of this element in the upper, drained horizon of organic soil (schlichting et al. 2002; litaor et al. 2004). the sequential phosphorus fractionation made it possible to discover the relative proportions of the various forms of p in the organic soils of the bellsund area. the distribution of the pi pool between its various fractions clearly indicated a significant impact of seabirds on two forms: pi�l and pi�camg. the very high concentrations of pi�l near the seabird colony resulted from the direct delivery of seabird droppings rich in this element. the considerable contribution of pi�l in the upper part of the skilvika profile could result from remineralization of plant litter. the contribution of the pi�camg form and its distribution in the soils at the study sites indicated a clear relationship with the fertilizing effect of the seabird colony which was probably due to the high content of ca and mg in the bird guano (fugler 1985). however the tendency for the pi�camg form to accumulate near the nutrient enrichment (eutrophication) source was also noted in american studies on bog soils subjected to strong fertilization (reddy et al. 1998). the contribution of this form of phosphorus increased with the depth in the skilvika profile which was not subject to concentrated fertilization. such a relationship in the distribution of this form was also observed in the peat soils of the moderate zone not subjected to direct fertilization (ziółek 2007). the seabirds seemed not to have an impact on the contribution of pi� feal in the pt pool. the greater contribution of this form in the sample underneath the seabird colony at dunderdalen indicated the direct fertilization effect of the seabirds, but it had no significant influence on the distribution of p among fractions. at both sites, the pi�camg fraction dominated in the pi pool, which could result from a high ph (6�7) of these soils. such a correlation is confirmed by the findings of many studies (ivanoff et al. 1998; ann et al. 2000; schlichting et al. 2002; litaor et al. 2004). most of the soil phosphorus is stored in organic forms, which has been reported in numerous studies (richardson & marshall 1986; ivanoff et al. 1998; reddy et al. 1998; robinson et al. 1998; schlichting et al. 2002; weintraub 2011; wang et al. 2012). such a situation occurred in the soils of the skilvika profile. the po�huac fraction played a significant role among the organic forms of phosphorus. at the skilvika site, this form dominated in the pt pool, which indicated the highly natural character of this site. research indicated that the greater the contribution of the organic p fraction associated with humic acids and the smaller the contribution of the inorganic fraction associated with fe and al in the pt pool, the smaller the extent of peat soil degradation (schlichting et al. 2002). very low values of the po�huac form occurred near the seabird colony and increased along the po�huac transect. this indicates a strong degradation of the organic soil by the seabirds. although most of the total soil phosphorus pool was stored in organic forms, mineral phosphorus dominated in the samples near the seabird colony, reaching 92% of the pt pool. large quantities of phosphorus from seabird droppings were delivered there. this delivery was a mixture of inorganic p and labile organic p that was readily converted to inorganic p by soil microbes. due to the short polar summer and consequently the short growing season, the vegetation showed a lower rate of mineral phosphorus compound intake (dowding et al. 1981; myrcha & tatur 1991; weintraub 2011). accordingly, the fertilizing effect of the seabirds in the polar climate is very pronounced indeed. the other fraction of po, po�res, indicated the presence of phosphorus associated with the highly durable organic plant material (ivanoff et al. 1998). the similar percentage contribution of this fraction in the pt pool at both sites under study indicates that the accumulation of this form was not linked to the impact of the seabirds. the ratio of the po to pi quantities (po/pi) is an indicator of the natural character of peat soils. schlichting et al. (2002) concludes that the large contribution of organic p and small contribution of inorganic p indicate that peats are less degraded and less mineralized. this is also confirmed by american studies (koch & reddy 1992; reddy et al. 1998). in samples near the seabird colony, the ratio was the lowest (from 0.1 to about 1.2), which resulted from the very intensive delivery of pi into the soils by the seabirds. at the silvika site, not subjected to m. ziółek & j. melke the impact of seabirds on phosphorus in organic soils citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 the intensive impact of the seabirds, the po/pi ratio was considerably higher (from 1.3 to 3.9), which indicates the highly oligotrophic character of these deposits. conclusions the content of pt and its various fractions show a large diversity in the organic soils of spitsbergen due to the fertilizing impact of seabirds. based on the pt content, which is a measure of the intensity of seabirds’ impact, it can be concluded that the nutrient enrichment of organic soils by birds in the polar zone is very strong. polar organic soils not subjected to the direct fertilizing seabirds’ impact contain amounts of pt similar to organic soils in other climate zones. the dominant fraction in the total pi pool in the organic soils on spitsbergen is the phosphorus fraction associated with calcium and magnesium, regardless of the impact of the seabirds. however, its distribution depends strongly on the distance from the seabird colony. the strong impact of the breeding seabird colony in the polar climate zone modifies the distribution of phosphorus among its organic and inorganic fractions, causing the ‘‘shifting’’ of phosphorus from organic to inorganic fractions. the delivery of large quantities of inorganic p disrupts its natural proportions in the soil phosphorus pool (primarily a reduced proportion of the po�huac fraction in the pt pool). the considerable contribution of the labile phosphorus fraction in the organic soils results from the direct fertilizing effect of seabirds. acknowledgements the authors thank the reviewers for their valuable comments and suggestions to improve the initial manuscript. references anderson w.b. & polis g.a. 1999. nutrient fluxes from water to land: seabirds affect plant nutrient status on gulf of california islands. oecologia 118, 324�332. ann y., reddy k.r. & delfino j.j. 2000. influence of chemical amendments on phosphorus immobilization in soils from a constructed wetland. ecological engineering 14, 157�169. bedrock c.n., cheshire m.v., chudek j.a., goodman b.a. & shand c.a. 1994. use of 31p-nmr to study the forms of phosphorus in peat soils. science of the total environment 152, 1�8. blümel w.d., eberle j. & weber l. 1993. verwitterung, genese und bodenverbreitung im liefdefjord/bockfjordgebiet (nw-spitzbergen)*untersuchungsmethoden und erste ergebnisse. (weathering, genesis and soil distribution in liefdefjord/bockfjord region [nw spitsbergen]*research methods and first results.) basler beiträge zur physiogeographie 15, 65�70. breuning-madsen h., ehlers c.b. & borggaard o.k. 2008. the impact of perennial cormorant colonies on soil phosphorus status. geoderma 148, 51�54. chang s.c. & jackson m.l. 1957. fractionation of soil phosphorus. soil science 84, 133�144. comerford n.b. 1998. soil phosphorus bioavailability. in j.p. lynch & j. deikman (eds.): phosphorus in plant biology. pp. 136�147. rockville, md: american society of plant physiologists. condron l.m. & newman s. 2011. revisiting the fundamentals of phosphorus fractionation of sediments and soils. journal soils sediments 11, 830�840. craft c.b. & richardson c.j. 1993. peat accretion and phosphorus accumulation along a eutrophication gradient in the northern everglades. biogeochemistry 22, 133�156. cross a.f. & schlesinger w.h. 1995. a literature review and evaluation of the hedley fractionation: applications to the biogeochemical cycle of soil phosphorus in natural ecosystems. geoderma 64, 197�214. cross a.f. & schlesinger w.h. 2001. biological and geochemical controls on phosphorus fractions in semiarid soils. biogeochemistry 52, 155�172. dobrovolsky v.v. 1990. geohimija počv špicbergena. (geochemistry of spitsbergen soils.) počvovedenie 2, 5�20. dowding p., chapin f.s. iii, wielgolaski f.e. & kilfeather p. 1981. nutrients in tundra ecosystems. in l.c. bliss et al. (eds.): tundra ecosystems: a comparative analysis. pp. 647�683. cambridge: cambridge university press. elser j.j., bracken m.e.s., cleland e.e., gruner d.s., harpole w.s., hillebrand h., ngai j.t., seabloom e.w., shurin j.b. & smith j.e. 2007. global analysis of nitrogen and phosphorus limitation of primary producers in freshwater, marine and terrestrial ecosystems. ecology letters 10, 1135�1142. eurola s. 1971. the middle arctic mire vegetation in spitsbergen. acta agralia fennica 123, 87�107. forman s.l. & miller g.h. 1984. time-dependent soil morphologies and pedogenic processes on raised beaches, bröggerhalvöya, spitsbergen, svalbard archipelago. arctic and alpine research 16, 381�394. fugler s.r. 1985. chemical composition of guano of burrowing petrel chicks (procellariidae) at marion island. in w.r. siegfried et al. (eds.): antarctic nutrient cycles and food webs. pp. 169�172. berlin: springer. godzik b. 1991. heavy metals and macroelements in the tundra of southern spitsbergen: the effect of little auk alle alle (l.) colonies. polar research 9, 121�131. göttlich k. & hornburg p. 1982. ein zeuge wärmzeitlicher moore im adventdalen auf spitzbergen (svalbard-archipel). (the peatbog in adventdalen on spitsbergen [svalbard archipeligo] as a witness of warm period. telma 12, 253�260. hawke d.j. & newman j. 2004. inventories and elemental accumulation in peat soils of forested seabird breeding islands, southern new zealand. australian journal of soil research 42, 45�48. the impact of seabirds on phosphorus in organic soils m. ziółek & j. melke 10 (page number not for citation purpose) citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 headley a.d. 1996. heavy metal concentrations in peat profiles from the high arctic. science of the total environment 177, 105�111. hogg e.h. & morton j.k. 1983. the effect of nesting gulls on the vegetation and soil of islands in the great lakes. canadian journal of botany 61, 3240�3254. ivanoff d.b., reddy k.r. & robinson s. 1998. chemical fractionation of organic phosphorus in selected histosols. soil science 163, 36�45. jóźwik z. & magierski j. 1992. v. trace elements in plants and soils of coastal plains of south bellsund (western spitsbergen). in j. repelewska-pękalowa & k. pękala (eds.): polar session. arctic natural environment problems. pp. 161�169. lublin: maria curie-skłodowska university press. klimowicz z., melke j. & uziak s. 1993. the influence of relief and lithology on soil formation in west spitsbergen. in: permafrost, sixth international conference proceedings. vol. 1. pp. 350�355. beijing, china: south china university of technology press. klimowicz z., melke j. & uziak s. 1997. peat soils in the bellsund region, spitsbergen. polish polar research 18, 25�39. klimowicz z., melke j., uziak s. & chodorowski j. 2008. soils of north-west part of wedel jarlsberg land against a background of the spitsbergen natural environment. lublin: maria curie-skłodowska university press. klimowicz z. & uziak s. 1988. soil-forming processes and soil properties in calypsostranda, spitsbergen. polish polar research 9, 61�71. koch m.s. & reddy k.r. 1992. distribution of soil and plant nutrients along a trophic gradient in the florida everglades. soil science society of america journal 56, 1492�1499. kuo s. 1996. phosphorus. in d.l. sparks et al. (eds.): methods of soil analysis. part 3. chemical methods. sssa book series no. 5. pp. 869�918. madison: soil science society of america, american society of agronomy. låg j. 1980. special peat formation in svalbard. acta agriculturae scandinavica 30, 205�210. ligęza s. & smal h. 2003. accumulation of nutrients in soils affected by perennial colonies of piscivorous birds with reference to biogeochemical cycles of elements. chemosphere 52, 595�602. litaor m.i., reichmann o., auerswald k., haim a. & shenker m. 2004. the geochemistry of phosphorus in peat soils of a semiarid altered wetland. soil science society of america journal 68, 2078�2085. lityński t., jurkowska h. & gorlach e. 1976. analiza chemicznorolnicza. (agricultural-chemistry analysis.) warszawa: pwn. mann o.h., sletten r.s. & ugolini f.c. 1986. soil development at kongsfjorden, spitsbergen. polar research 4, 1�16. melke j. 1999. preliminary studies of fissure and slope peats in the calypsostranda and lyellstranda region, west spitsbergen. in j. repelewska-pękalowa (ed.): polish polar studies. 26th international polar symposium. pp. 171�175. lublin: maria curie-skłodowska university press. melke j. & chodorowski j. 2006. formation of arctic soils in chamberlindalen, bellsund, spitsbergen. polish polar research 27, 119�132. mulder c.p.h., jones h., kameda k., palmborg c., schmidt s., ellis j.c., orrock j.l., wait d.a., wardle d.a., yang l., young h., croll d.a. & vidal e. 2011. impacts of seabirds on plant and soil properties. in c.p.h. mulder et al. (eds.): seabird islands: ecology, invasion, and restoration. pp. 135�176. new york: oxford university press. mun h.t. 1997. effects of colony nesting of adrea cinerea and egretta alba modesta on soil properties and herb layer composition in pinus densiflora forest. plant and soil 197, 55�59. myrcha a. & tatur a. 1991. ecological role of the current and abandoned penguin rookeries in the land environment of the maritime antarctic. polish polar research 12, 3�24. parent l.e. & khiari l. 2003. nitrogen and phosphorus balance indicators in organic soils. in l.e. parent & p. ilnicki (eds.): organic soils and peat materials for sustainable agriculture. pp. 105�136. boca raton, fl: crc press. reddy k.r., wang y., debusk w.f., fisher m.m. & newman s. 1998. forms of soil phosphorus in selected hydrologic units of the florida everglades. soil science society of america journal 62, 1134�1147. richardson c.j. & marshall p.e. 1986. processes controlling movement, storage, and export of phosphorus in a fen peatland. ecological monographs 56, 279�302. robinson j.s., johnston t.c. & reddy k.r. 1998. combined chemical and 31p-nmr spectroscopic analysis of phosphorus in wetland organic soils. soil science 163, 705�713. sapek a. & sapek b. 1997. metody analizy chemicznej gleb organicznych. materialy instruktażowe 115. (methods for chemical analysis of organic soils. instructional materials 115.) falenty, poland: institute for land reclamation and grassland farming. schlichting a., leinweber p., meissner r. & altermann m. 2002. sequentially extracted phosphorus fractions in peatderived soils. journal of plant nutrition and soil science 165, 290�298. smil v. 2000. phosphorus in the environment: natural flows and human interferences. annual review energy environment 25, 53�88. speir t.w. & cowling j.c. 1984. orthogenetic soils of the cape bird adelie penguin rookeries, antarctica. polar biology 2, 207�212. tatur a. 1989. ornithogenic soils of the maritime antarctic. polish polar research 10, 481�532. tatur a. 2002. ornithogenic ecosystems in the maritime antarctic*formation, development and disintegration. in l. beyer & m. bölter (eds.): geoecology of terrestrial antarctic ice-free coastal landscapes, ecological studies 154. pp. 161�184. berlin: springer. thomas g.w. 1996. soil ph and soil acidity. in d.l. sparks et al. (eds.): methods of soil analysis. part 3. chemical methods. sssa book series no. 5. pp. 869�918. madison: soil science society of america, american society of agronomy. uziak s. 1992. polish pedological studies on spitsbergen. a review. geographia polonica 60, 67�78. m. ziółek & j. melke the impact of seabirds on phosphorus in organic soils citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 wang g., bao k., yu x., zhao h., lin q. & lu x. 2012. forms and accumulation of soil p in a subalpine peatland of mt. changbai in northeast china. catena 92, 22�29. weintraub m.n. 2011. biological p cycling in arctic and alpine soils. in e.k. bünemann et al. (eds.): phosphorus in action. biological processes in soil phosphorus cycling. pp. 295�316. berlin: springer. zelikson e.m. 1971. palinologičeskoe issledovanie golocenovogo torfjanika na špicbergene. (palynological investigation of a holocene peat deposit from spitsbergen.) in m.i. neustadt (ed.): palinologija golocena. (holocene palynology.) pp. 199�212. moscow: academy of science of the sssr. zagórski p. 2005. nw part of wedel jarlsberg land (spitsbergen, svalbard, norway), orthophotomap, scale 1:25000. lublin: department of geomorphology, maria curie-skłodowska university/tromsø: norwegian polar institute. ziółek m. 2007. phosphorus forms in organic soils with a varying degree of transformation (on the example of the lublin polesie region). polish journal of soil science 40, 179�194. the impact of seabirds on phosphorus in organic soils m. ziółek & j. melke 12 (page number not for citation purpose) citation: polar research 2014, 33, 19986, http://dx.doi.org/10.3402/polar.v33.19986 http://www.polarresearch.net/index.php/polar/article/view/19986 http://dx.doi.org/10.3402/polar.v33.19986 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice referees25(1).indd 81polar research 25(1), 81–84 polar research’s referees it is once again time to thank all the scientists— not only those whose names are printed on the following pages—who have kindly served as referees for polar research during the last couple of years. there is a widespread sentiment that reviewing manuscripts is an almost thankless task. yet reviewers agree to it anyway. why? this was one of the questions addressed in a focus group study commissioned by the publishers elsevier (mulligan 2004). the study confi rmed that reviewers are motivated by a number of factors. chief among them is the perception that it is one’s academic duty to review others’ papers since one’s own work is similarly reviewed (and, thereby, often improved). additional incentives for referees include a wish to remain up-to-date in their fi elds and the hope that reading new work will stimulate fresh ideas for their own research. the study indicates that the reputation of the journal strongly infl uences a reviewer’s decision to agree to examine a manuscript, and it helps if the referee personally knows the individual requesting the review. the elsevier study also revealed that referees believe that reviewing is growing more burdensome. referees are being swamped with requests to review manuscripts and the turnaround times demanded by editors—themselves pressured by authors who want fast decisions and rapid publication—are becoming shorter. some fi elds are more impacted by this than others. scientists in “high consensus” fi elds—in which scholars agree about what constitutes good research and fruitful theory—are likelier to compete for priority in announcing their fi ndings and to worry about being scooped by rivals (hargens 1990). competition for priority is more pronounced in the physical sciences than in the biological sciences (hargens 1990 and sources cited therein), yet expectations for speedier turnaround and publication pervade scientifi c publishing. these expectations have surely been infl uenced by the possibilities of computer technology, which allows for lightning-fast communication and quicker preparation of documents and graphics. (as with so many other aspects of modern life, the better the technology, the more we humans must scramble to keep pace.) the internet revolution seems to have aggravated the situation for reviewers in one further respect. referees in the elsevier focus group felt that online review, which is in use at many journals (but not yet polar research), benefi ts authors and editors but places an extra load on the shoulders of reviewers. they have to print out manuscripts themselves and must confi ne their comments to restrictive online formats. (see gladwell [2002] for a look at how and why many people—“knowledge workers”, in particular— continue to rely on paper in spite of the prediction that it would be made largely obsolete by today’s information technology.) editors who participated in the elsevier study felt that attracting and keeping good referees is getting harder. rushed, overburdened and sometimes feeling unappreciated, referees can at least take heart in the fact that editors are deeply concerned with their plight as well as with the larger issues relating to peer review. in september 2005, for example, 470 participants representing 38 nations gathered in chicago for three days for the fifth international congress on peer review and biomedical publishing. presentations at the conference covered topics such as confl icts of interest, blind peer review and comparisons of the quality of reviews by editoras opposed to author-suggested referees. though a majority of the talks and posters were specifi c to biomedical publishing, many contained messages of broader relevance. (for the complete program see www.amaassn.org/public/peer/program.html.) peer review is a common topic of discussion in european science editing, the (peer reviewed) journal of the european association of science editors. what is the purpose of peer review? as mulligan (2004) points out, there is no single set of objectives which is universally in use. the consensus in the focus group in the elsevier study was that “peer review should prevent an author making egregious claims on minimal results... it should ensure that a consistent and appropriate methodology is used, and that recent reputable work...is correctly referenced and acknowledged” (mulligan 2004: 4). these basic criteria form the backbone of polar research’s reviewer’s guidelines and, presumably, those of other scientifi c journals. on these grounds, referees evaluate manuscripts; those failing to satisfy the most important criteria are rejected by editors. according to meadows (2005: 114), the rejection rate of the “average” natural science journal does not exceed a third of submissions. interestingly, in 82 polar research’s referees the social sciences—where there is low consensus about what constitutes valuable research— journals reject two-thirds or more of their submissions, and they require more revisions from authors (meadows 2005; see also hargens 1990). in contrast to many journals, polar research is multidisciplinary; its scope is largely defi ned by geography and it therefore competes for submissions with journals covering particular scientific fi elds. biology, geology and oceanography are all well representd in polar research: combined, these three disciplines represent about three-quarters of the articles in the journal (fig. 1a). in terms of geographical coverage, the nordic arctic, particularly svalbard and the barents sea, continues to dominate the pages of polar research (fig. 1b). only about 6 % of the journal’s articles concern the antarctic. this is an imbalance that the journal’s contributors, referees and readers can help to rectify by spreading the word that the scope of polar research encompasses both poles. helle v. goldman norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, goldman@ npolar.no. other/multidisciplinary climatology/atmos. hydrology glaciology oceanography geology biology other/multiple greenland/iceland north american arctic russian arctic/seas continental nordic arctic/ nordic seas/svalbard antarctica fig. 1. (a) a rough breakdown of the scientifi c fi elds represented in polar research articles; (b) the geographic areas that the journal’s articles concern. the data are drawn from the last fi ve years. references gladwell, m. 2002: the social life of paper: looking for method in the mess. the new yorker 25 march, 92–96. hargens, l. l. 1990: variation in journal peer review systems: possible causes and consequences. j. am. med. assoc. 263, 1348–1352. meadows, j. 2005: differences between the sciences in their handling of the research literature. eur. sci. ed. 31, 113– 116. mulligan, a. 2004: is peer review in crisis? perspect. publ. 2, 1–6. (a) (b) 83polar research 25(1), 81–84 becky alexander, university of washington, usa ole b. andersen, danish national space center, denmark peter g. appleby, university of liverpool, uk steven a. arcone, cold regions research and engineering laboratory, usa holger auel, university of bremen, germany wilfried bauer, rwth aachen university, germany martin beniston, university of fribourg, switzerland matthew bennett, bournemouth university, uk knut bjørlykke, university of oslo, norway johan blindheim, institute of marine research, norway dierk p. g. blomeier, norwegian polar institute, norway corey j. a. bradshaw, charles darwin university, australia keith brander, international council for the exploration of the sea, denmark howard i. browman, institute of marine research, norway iain b campbell, land and soil consultancy services, new zealand alex j. cannon, meteorological service of canada, canada hanne h. christiansen, the university centre in svalbard, norway andrew davidson, australian antarctic division, australia daniel delille, national center of scientifi c research, france julian dowdeswell, scott polar research institute, uk dennis g. dye, frontier research center for global change, japan henning dypvik, university of oslo, norway bernd etzelmüller, university of oslo, norway julian b. fischer, us fish and wildlife service, usa i. v. florinsky, institute of mathematical problems of biology, russia giles m. foody, university of southampton, uk steven l. forman, university of illinois, usa jean-marc fromentin, french research institute for exploitation of the sea, france robert gilbert, queen’s university, canada philip a. gillibrand, scottish association for marine science, uk john gjelberg, hydro research centre, norway william gould, international institute of tropical forestry, puerto rico viktor gouretski, max planck institute for meteorology, germany t. g. allan green, waikato university, new zealand sveinn are hanssen, university of tromsø, norway e. walter helbling, photobiological station at playa union, argentina gerhard j. herndl, royal netherlands institute for sea research, the netherlands j. mark hipfner, canadian wildlife service, canada g. j. greg hofmeyr, university of pretoria, south africa ólafur ingólfsson, university of iceland, iceland elisabeth isaksson, norwegian polar institute, norway george d. jackson, university of tasmania, australia l. allan james, university of south carolina, usa hester jiskoot, university of lethbridge, canada ludger kappen, university of kiel, germany michael karcher, alfred wegener institute for polar and marine research, germany ron kwok, jet propulsion laboratory, usa mary-anne lea, university of tasmania, australia victoria lytle, wcrp climate and cryosphere international project offi ce, norway harald loeng, institute of marine reseach, norway j. i. lópez-moreno, pyrenean institute of ecology csic, spain connie lovejoy, laval university, canada rosa margesin, leopold franzens university, austria thomas martin, university of kiel, germany robert v. miller, oklahoma state university, usa anders mosbech, national environmental research institute, denmark ellen mosley-thompson, the ohio state university, usa ransom a. myers, dalhousie university, canada adrian neal, university of wolverhampton, uk patrick j. neale, smithsonian institution, usa marco nigro, university of pisa, italy carsten riis olesen, national environmental research institute, denmark brad page, south australian research and 84 polar research’s referees development institute, australia ana pintado, complutense university of madrid, spain francesco regoli, polytechnic university of marches-ancona, italy gregory j. robertson, canadian wildlife service, canada martin j. siegert, university of bristol, uk elizabeth sinclair, national oceanic and atmospheric administration, usa walter h. f. smith, national oceanic and atmospheric administration, usa hans-ulrich steeger, university of muenster, germany ron steel, the university of texas at austin, usa daniel steinhage, alfred wegener institute, germany douglas stow, san diego state university, usa nicholas tyler, university of tromsø, norway roberto udisti, university of florence, italy arnoldo valle-levinson, university of florida, usa john van den hoff, australian antarctic division, australia alan p. m. vaughan, british antarctic survey, uk virginia e. villafañe, photobiological station at playa union, argentina peter wadhams, university of cambridge, uk david walsh, naval research laboratory, usa jenny g. webster-brown, university of auckland, new zealand meredith williams, university of newcastle upon tyne, uk peter winsor, woods hole oceanographic institution, usa david worsley, rogaland research institute, norway daqing yang, university of alaska fairbanks, usa kathy l. young, york university, canada richard e. young, university of hawaii, usa howard zebker, stanford university, usa << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice no job name late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbardpor_173 283..297 frauke kubischta,1 karen luise knudsen,2 anu kaakinen1 & veli-pekka salonen1 1 department of geosciences and geography, division of geology, university of helsinki, gustaf hällströmin katu 2a, po box 64, fi-00014 helsinki, finland 2 department of earth sciences, aarhus university, høegh-guldbergs gade 2, dk-8000 århus c, denmark abstract benthic foraminiferal assemblages from nordaustlandet, svalbard, are described for the first time with the objective of reconstructing the palaeoenvironmental conditions in the area during the late quaternary. investigations were carried out on marine deposits exposed along the southern shores of murchisonfjorden. five foraminiferal assemblages (a1–a5), representing different palaeoenvironmental conditions, were identified from the marine intervals, i.e., the cassidulina reniforme–elphidium albiumbilicatum assemblage (a1) from the early weichselian, the islandiella helenae–cibicides lobatulus assemblage (a2) from the early weichselian, the cibicides lobatulus–cassidulina reniforme assemblage (a3) from marine isotope stage 3, the elphidium albiumbilicatum assemblage (a4) from the early holocene and the astrononion gallowayi assemblage (a5) from the mid-holocene. assemblages a1–a5 are compared with modern and fossil quaternary assemblages from arctic regions. particularly notable is the fact that a well-defined middle weichselian assemblage in svalbard is described for the first time, i.e., the cibicides lobatulus– cassidulina reniforme assemblage. all the assemblages from nordaustlandet represent glacier-distal, inner-shelf environments with an open connection to the ocean. the results reveal the occurrence of three marine intervals (ice-free periods) in the north-western part of nordaustlandet during the weichselian, as well as ice-free conditions during most of the holocene. a comparison of the assemblages from nordaustlandet with previously published foraminiferal zones from onshore sections elsewhere in svalbard show some degree of similarity, but also show considerable variation in species compositions, presumably caused by local environmental differences. keywords quaternary stratigraphy; benthic foraminifera; palaeoenvironments; arctic; svalbard. correspondence frauke kubischta, department geosciences and geography, division of geology, university of helsinki, gustaf hällströmin katu 2a, po box 64, fi-00014 helsinki, finland. e-mail: frauke.kubischta@helsinki.fi doi:10.1111/j.1751-8369.2010.00173.x nordaustlandet is the north-easternmost island of the svalbard archipelago (76–81°n, 10–30°e; fig. 1), separated from the main island, spitsbergen, by hinlopenstretet. much of nordaustlandet is covered by two large ice caps, vestfonna and austfonna, and only small areas along the northern, north-western and southern coasts are free of ice (fig. 1). rapid isostatic uplift after the last deglaciation has led to the exposure of marine deposits that are now accessible in a number of vertical coastal sections, a few metres high, containing rich biostratigraphical and sedimentological information (blake 1961, 1981). to complement previous studies on the stratigraphy of quaternary sediments from around svalbard by lønne & mangerud (1991), mangerud & svendsen (1992), andersen et al. (1996) and houmark-nielsen & funder (1999), kaakinen et al. (2009) have performed sedimentological studies at a series of exposures in the south-eastern part of murchisonfjorden, nordaustlandet. they found that marine sands and gravels are interlayered with tills deriving from multiple glacier advances throughout the weichselian. these marine sands and gravels were also found to contain pelecypod remains and foraminifera, but the faunal material in the sections was not investigated in any detail. overall, quaternary research on nordaustlandet has previously focused on glacial geology, geomorphology and palaeolimnological studies, rather than on polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 283 mailto:kubischta@helsinki.fi fig. 1 (a) location of the study area in murchisonfjorden in the north-western part of nordaustlandet, svalbard, with an inserted close-up of the murchisonfjorden area, and (b) the sections in isvika. abbreviations: b., brøggerhalvøya; bl., blåfjorddalen; g., guldalen; k., kongsfjordhallet; k.w., kapp wijk; l., linnéelva; p., poolepynten; sa., sarsbukta; sk., skilvika; t., talavera; v., visdalen; wi., wijdefjorden. late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbard f. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd284 biostratigraphy and sedimentology of the marine deposits. donner & west (1957, 1995) examined the weichselian deglaciation and emergence history at brageneset (fig. 1), and reported observations on the glacial geology of nordaustlandet. the ice-movement history of nordaustlandet, including the radiocarbon age determination of raised beaches, land uplift, morphological investigations and climatic implications of the occurrence of mytilus edulis, were studied by blake (1961, 1962, 2006). in his phd thesis, blake (1962) even described reworked foraminifera within tills in the murchisonfjorden area. hyvärinen (1969, 1970) established a pollen stratigraphy for the last 10 000 years based on lake sediment records from nordaustlandet and spitsbergen. these studied cores also revealed marine strata with abundant benthic foraminifera, but hyvärinen (1969) only mentioned three taxa, determined to genus level, from the marine interval. this points to a clear lack of knowledge of the marine biostratigraphy of the area. foraminiferal palaeoecological and stratigraphical studies have, however, previously been performed for several core records from fjords and the adjacent shelf areas in svalbard (e.g., svendsen et al. 1996; wollenburg et al. 2001; koç et al. 2002; hald et al. 2004; ślubowska et al. 2005; korsun et al. 2006; rasmussen et al. 2007; ślubowska-woldengen et al. 2007; hald & korsun 2008; majewski et al. 2009), as well as for raised marine deposits from coastal sections around the archipelago (e.g., feyling-hanssen 1965; nagy 1984; miller et al. 1989; landvik et al. 1992; lycke et al. 1992; mangerud et al. 1992; svendsen & mangerud 1992; ingólfsson et al. 1995; bergsten et al. 1998; mangerud et al. 1998). the aim of this study is to examine the micropalaeontological record from some of the raised marine deposits in murchisonfjorden, nordaustlandet, and to use the benthic foraminifera to infer, on a relative and qualitative basis, the palaeoenvironmental conditions such as water temperature, salinity, water depth and current energy for the late quaternary in the area. this is achieved by a comparison with modern assemblage distributions of foraminifera, particularly in the svalbard area, but also in adjacent arctic regions such as northern norway, northern russia and greenland. in addition, an attempt is made to correlate the different marine units in the coastal sections in murchisonfjorden with similar deposits described from other onshore sections around the svalbard archipelago. late quaternary sections in murchisonfjorden the research material presented here was collected from a coastal area west of vestfonna during a 3-week-long field campaign in july–august 2007. the seven sections, which were recently reported on by kaakinen et al. (2009) are situated along the shores of isvika on the southern side of murchisonfjorden in nordaustlandet, svalbard (fig. 1). only five of these sections were used for optically stimulated luminescence (osl) dating and for the present study (fig. 2). kaakinen et al. (2009) identified a total of 12 lithofacies units, and recognized evidence from three depositional sequences. each sequence includes till unit(s) overlain by sorted marine fig. 2 lithostratigraphical correlations of the sections in isvika, murchisonfjorden, with indication of sediment facies, unit numbers, foraminiferal sample locations and mean ages. modified from kaakinen et al. (2009). late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbardf. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 285 sands and gravels. the sedimentological analyses indicated that the tills were deposited as a result of lodgement, melt-out and deformation processes, whereas the raised marine strata were interpreted to represent upper shoreface, foreshore, and littoral gravels and beach deposits. the ages of the deposits, which were constrained by osl dating of well-bleached quartz grains and accelerator mass spectrometry (ams) 14c age determinations of shells, range from over 80 ky to around 6 ky (kaakinen et al. 2009). two samples gave ages within the time frame of the phantomodden interstadial, marine isotope stage (mis) 5c-a (mangerud et al. 1998), and one was dated to mis 3 and correlated with the kapp ekholm interstadial. four age determinations cover the holocene epoch, with the oldest results being close to the time of the deglaciation of the island, and two results representing the mid-holocene. the grain sizes of the marine strata ranges from clayey silt to gravel, and they contain a rich macroand microfauna such as mya truncata, astarte sp., hiatella arctica, astarte borealis and chlamys islandica, foraminifera and some ostracoda, although in varying states of preservation. the younger shells are better preserved, less mechanically abraded and have been exposed less to calcareous dissolution than those in the older units. the relatively poor preservation of both macroand microfossil shells in the older sediments is considered to be the result of overriding during subsequent glaciations, plus frost action and post-depositional solifluction, but the foraminiferal tests may also have been damaged further during the laboratory treatment (see below). material and methods the nine samples that were available for this foraminiferal study were originally used to determine water contents of the sediment units, from which osl dates were obtained (sediment units 1, 2, 6, 8, 11 and 12; no osl dates were carried out from units 5, 7, 9 and 10) (kaakinen et al. 2009). as a result of the required laboratory treatment for water content determination (heating to 105°c for several hours), some specimens, particularly small or thin-shelled tests and agglutinated tests, may have been damaged. yet, we consider the material to be sufficient for this first overview of foraminiferal assemblages in the quaternary deposits of nordaustlandet. after drying (dry weights vary from 40.2 to 49.6 g), the samples for foraminiferal analysis were wet-sieved through a stack of sieves with mesh sizes of 1.000, 0.250, 0.125 and 0.063 mm. the fractions were dried on the sieves and then stored in glass vials for future analysis. for foraminiferal analysis, the 0.125-mm fraction was concentrated by soap flotation to avoid the excessive use of chemicals, and was again dried in an oven at 50°c. in two samples (samples 13 and 41), the foraminiferal shells were still mixed with sand grains after flotation with soap. therefore, the usual heavy liquid method (c2cl4) was subsequently applied for the preparation of these, following the method described by feyling-hanssen et al. (1971) and knudsen (1998). of the nine samples that were available for foraminiferal analysis (fig. 2), one did not contain any foraminifera (sample 20), and one contained only two specimens of cibicides lobatulus (sample 19; table 1). these two samples are not further discussed. in samples with low abundances of foraminifera (samples 14, 7, 8, 27, 42 and 41), all the specimens were determined and picked, but only approximately one-eighth of sample 13 was counted. a total of 21 calcareous benthic taxa were identified. one sample (14) contained a single planktonic specimen. agglutinated species are generally not preserved in this kind of material, and only a few specimens were found. the counts and the original references for all the species and species groups are listed in table 1. the number of specimens per 100 g of dry sediment is generally low, ranging from ca. 75 to 14 200 in the fossiliferous samples. a faunal diversity index, defined by walton (1964) as the number of ranked species that accounts for 95% of a counted assemblage, was applied to the assemblages. this faunal diversity index and the number of benthic calcareous species have values of 6–10 and 7–15, respectively. elphidium albiumbilicatum and elphidium hallandense are grouped as elphidium albiumbilicatum/hallandense in one of the samples (sample 13; fig. 3; table 1), because the occurrences of transition forms between the two species made a separation difficult. both species indicate shallow and/or brackish conditions, but as elphidium hallandense is a high-arctic species, whereas elphidium albiumbilicatum often occurs in sub-arctic waters, a possible climatic indication may be lost by this grouping (see the discussion in knudsen 1978). however, the climatic indication of elphidium albiumbilicatum is still relatively uncertain, as discussed by hansen & knudsen (1995). because of the poor preservation state, some species of the genus elphidium have also been grouped (as elphidium spp.). this group is suggested primarily to include elphidium excavatum f. clavata, elphidium albiumbilicatum and elphidium hallandense. elphidium spp. is a shallow-water group that is generally tolerant to changes in salinity (e.g., murray 1991, 2006). species within the family polymorphinidae are also grouped. agglutinated late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbard f. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd286 and planktonic taxa are not included in the percentage calculations of fig. 3. foraminiferal assemblages and palaeoenvironments five foraminiferal assemblage zones (a1–a5) were identified on the basis of the faunal compositions in the material from nordaustlandet, according to the definition by salvador (1994). assemblage zones a1–a3 are represented by only one sample each, whereas assemblage zones a4 and a5 are comprised of two samples each. the percentage distribution of foraminiferal taxa in assemblage zones a1–a5 is shown in fig. 3 together with a composite lithostratigraphical log, the facies sequences, the sedimentary units and the mean age of each sample (after kaakinen et al. 2009). a description of the foraminiferal contents of each assemblage zone is given below, together with a palaeoenvironmental interpretation, which is summarized in table 2. the lithological descriptions and age determinations are based on earlier investigations in the area (kaakinen et al. 2009). assemblage zone a1: cassidulina reniforme– elphidium albiumbilicatum assemblage (sample 41) description. the sediment consists of well-sorted fine to medium sand with both whole and broken pelecypod shells, mainly of mya truncata. the sample contains an extremely rich foraminiferal assemblage with a faunal diversity of 7, and is dominated by cassidulina reniforme and elphidium albiumbilicatum, with buccella frigida and islandiella helenae as the second most abundant species. elphidium excavatum (as forma clavata; see feylinghanssen 1972), haynesina orbiculare, cibicides lobatulus, nonionellina labradorica and elphidium hallandense also play an important role (fig. 3). table 1 foraminiferal counts and faunal characteristics of eight samples from isvika, murchisonfjorden, svalbard. the original references and descriptions of the taxa are reported in ellis & messina (1949, and supplements up to 2007). for logs and sedimentary units, see figs. 2 and 3. agglutinated and planktonic foraminifera are excluded from the percentage calculations of fig. 3. sample no. 19 14 13 7 8 27 42 41 log/unit 4 3/8 3/8 2/12 2/11 5/6 7/2 7/1 sample weight in g (dry) 45 40 41 46 44 46 50 45 specimens counted 2 224 734 237 320 117 34 825 specimens per 100 g of sediment 560 1780 510 720 250 75 14200 faunal diversity (walton 1964) 10 10 6 8 8 7 no. of species 1 13 15 12 14 11 7 14 assemblage no. a5 a5 a4 a4 a3 a2 a1 astrononion gallowayi loeblich & tappan, 1953 38 342 21 44 6 1 buccella frigida (cushman, 1922) 12 13 3 3 3 2 91 cassidulina reniforme nørvang, 1945 31 150 35 43 25 1 314 cibicides lobatulus (walker & jacob, 1798) 2 36 28 54 38 37 10 5 elphidium albiumbilicatum (weiss, 1954) 20 47 70 108 177 elphidium albiumbilicatum/hallandense 17 elphidium excavatum (terquem, 1875) 28 22 33 29 14 4 65 elphidium hallandense brotzen, 1943 18 29 22 3 9 elphidium incertum williamson, 1858 1 elphidium magellanicum heron-allen & earland, 1932 1 elphidium spp. 7 12 6 3 5 2 7 fissurina spp. 7 1 haynesina orbiculare (brady, 1881) 5 42 1 2 1 15 islandiella helenae feyling-hanssen & buzas, 1976 13 9 3 17 14 114 lagena spp. 2 nonionellina labradorica (dawson, 1860) 5 12 22 16 4 9 nonion matchigaricus voloshinova, 1952 6 patellina corrugata williamson, 1858 1 5 stainforthia loeblichi (feyling-hanssen, 1954) 2 3 trifarina fluens (todd, 1947) 1 polymorphinidae 9 3 2 1 9 indeterminate, calcareous taxa 1 4 6 agglutinated species 4 1 7 planktonic species 1 late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbardf. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 287 fig. 3 percentage distribution of benthic foraminifera from sections in isvika, nordaustlandet. actual counts are inserted for sample 42, which was poor in specimens. a composite lithostratigraphic log is shown on the left-hand side, together with the sedimentary units and facies according to kaakinen et al. (2009), and the subdivisions in foraminiferal assemblage zones a1–a5 are indicated on the right-hand side. late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbard f. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd288 palaeoenvironment and age. cassidulina reniforme is an arctic indicator species (e.g., hald & korsun 1997). the relatively high abundance of specimens of the genus elphidium would indicate relatively shallow water and/or fluctuating salinity (murray 1991, 2006), and elphidium albiumbilicatum may be an indicator for mild sub-arctic conditions, as well as for shallow conditions and reduced salinity (e.g., lutze 1965; see discussion in knudsen 1978). it does, however, also occur in open ocean conditions off north and north-west iceland (rytter et al. 2002; jennings et al. 2004). islandiella helenae is, on the other hand, a high-arctic open-ocean species requiring stable salinity (korsun et al. 1995; hald & korsun 1997), and cibicides lobatulus is an attached species indicating relatively strong bottom-water currents (haynes 1973; murray 1991, 2006; hald & korsun 1997). this latter species also prefers relatively shallow but open marine environments (hansen & knudsen 1995; rytter et al. 2002). in summary, assemblage zone a1 was most probably deposited in relatively open marine waters on the inner shelf during a high sea-level stand. kaakinen et al. (2009) interpreted the present sandy bed as a slab/layer, which had been incorporated into the glacial diamicton of sedimentary unit 1 (figs. 2, 3), and the well-preserved foraminifera are considered to represent an in situ assemblage. the age of sedimentary unit 1 has been estimated to 93–65 ky, i.e., early weichselian (kaakinen et al. 2009), and the marine sedimentary unit is considered to represent an interval of high sea-level stand. assemblage zone a2: islandiella helenae– cibicides lobatulus assemblage (sample 42) description. the sediment consists of bimodal pebblerich, very coarse stratified sand with some shell fragments (unit 2; figs. 2, 3). the assemblage, which is poor in foraminifera, is dominated by large specimens of islandiella helenae and cibicides lobatulus, together with elphidium excavatum f. clavata. accessory species are elphidium spp., buccella frigida and haynesina orbiculare. palaeoenvironment and age. the dominance of large robust specimens in this fauna presumably indicates that it represents a residual fauna, in which the smaller specimens have been dissolved or mechanically damaged, and the fine particles have been washed out. another possibility is that the specimens have been redeposited into this unit from an older deposit. islandiella helenae and cibicides lobatulus both indicate open-ocean and glacierdistal environments, and additionally, cibicides lobatulus is a high-energy indicator. buccella frigida is often found together with cibicides lobatulus in glacier-distal environments with relatively stable salinity (haynes 1973), and it table 2 stratigraphical correlation and environmental interpretation of the five foraminiferal assemblages, a1–a5, from isvika, murchisonfjorden. assemblages environments stratigraphical correlation a5 astrononion gallowayi glacier-distal, inner shelf open ocean connection relatively stable environment slightly lowered salinity upwards increase in bottom-water currents mid-holocene a4 elphidium albiumbilicatum glacier-distal, inner shelf open ocean connection high-energy environment slightly lowered salinity high-energy environment seasonal sea-ice cover early holocene a3 cibicides lobatulus–cassidulina reniforme glacier-distal, inner shelf open ocean connection high-energy environment relatively stable salinity middle weichselian (mis3) a2 islandiella helenae–cibicides lobatulus glacier-distal, inner shelf open ocean connection high-energy environment early weichselian a1 cassidulina reniforme–elphidium albiumbilicatum glacier-distal, inner shelf open ocean connection relatively stable environment slightly lowered salinity high foraminiferal productivity early weichselian late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbardf. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 289 is often related to sandy sediments (e.g., hansen & knudsen 1995; hald & korsun 1997). it is difficult to interpret a residual assemblage, but there is some indication of a glacier-distal, high-energy environment for assemblage zone a2. the interpretation of a lag deposit for this zone is supported by the sedimentological indication of an upper shoreface to foreshore environment of unit 2 (kaakinen et al. 2009). the age of this unit has been estimated to 93–73 ky, i.e., early weichselian (kaakinen et al. 2009). assemblage zone a3: cibicides lobatulus– cassidulina reniforme assemblage (sample 27) description. the sediment consists of well to moderately sorted very coarse sand and granules, as well as thin pebble beds with sharp bases and occasional cobble horizons (unit 6; figs. 2, 3). the assemblage has a faunal diversity of 8 and is dominated by cibicides lobatulus and cassidulina reniforme, followed by elphidium excavatum f. clavata and islandiella helenae, as well as several other accessory species. it differs from assemblage zone a1 by a decrease in the percentage of buccella frigida, and by an increase in cibicides lobatulus, as well as in most of the accessory species (fig. 3). palaeoenvironment and age. the dominance of the two species cibicides lobatulus and cassidulina reniforme in this assemblage indicates deposition in an arctic, relatively shallow environment with strong bottom-water currents. both cibicides lobatulus and islandiella helenae indicate glacier-distal conditions, whereas the influence of the opportunistic elphidium excavatum f. clavata would be an indication of less stable environmental conditions (see hald et al. 1994). astrononion gallowayi often occurs together with cibicides lobatulus in areas with strong bottom currents and stable salinity (hald & korsun 1997; rytter et al. 2002). assemblages dominated by cibicides lobatulus are recorded in high-energy environments in the fjords of svalbard, often related to shallow thresholds across the fjords (hald & korsun 1997, elverhøi et al. 1980), and in fjord and inner shelf areas of eastern greenland (jennings & helgadóttir 1994). in summary, the environmental indication of assemblage zone a3 is rather close to that of assemblage zone a1, although with relatively stronger bottom currents. the faunal indication of a high energy level at the sea floor is in agreement with the interpretation of upper shoreface to littoral gravels with beach deposits for sedimentary unit 6 (kaakinen et al. 2009). ages of 37.0 and 40.0 ky were obtained, i.e., a middle weichselian age (mis 3) (kaakinen et al. 2009). assemblage zone a4: elphidium albiumbilicatum assemblage (samples 8 and 7) description. sample 8 was collected from a sandy pebble gravel bed with shell fragments, which grades upward into shingle gravel (unit 11). sample 7 was obtained from a clast-supported diamicton bed with a fine sand matrix containing shell fragments (unit 12; figs. 2, 3). elphidium albiumbilicatum and cibicides lobatulus are the dominant species, there are high abundances of astrononion gallowayi, cassidulina reniforme and elphidium excavatum f. clavata, and several accessory species occur. the faunal diversity is 8 in the lower sample and 6 in the upper sample. compared with the underlying marine beds, this assemblage is particularly characterized by the pronounced increase in astrononion gallowayi and elphidium albiumbilicatum, and nonionellina labradorica is more frequent than has been previously seen. the occurrence of stainforthia loeblichi is unique for assemblage a4. palaeoenvironment and age. the strong influence of cassidulina reniforme, elphidium excavatum f. clavata and buccella frigida, together with cibicides lobatulus and elphidium hallandense indicate arctic, shallow-water conditions and relatively strong bottom currents. the disappearance of elphidium hallandense, which prefers a silty and sandy sea floor (hansen & knudsen 1995), in sample 7 may be a result of relatively high current velocity, as also indicated by the coarsening of the sediment towards the top of the unit (fig. 3). this idea is supported by the appearance of cibicides lobatulus in sample 8. the presence of species such as nonionellina labradorica and astrononion gallowayi indicates a relatively stable salinity in a glacier-distal environment (e.g., korsun et al. 1995; hald & korsun 1997), whereas stainforthia loeblichi is considered to be an indicator of seasonal ice cover in the area (steinsund 1994). the environmental indication of assemblage a4 supports the interpretation by kaakinen et al. (2009) of a foreshore zone for the sedimentary environment of sample 8 (unit 11). their interpretation of unit 12 as representing a debris flow cannot be confirmed from the assemblage. if it represents a re-deposited fauna, as suggested by the age determination, it could originate from a marine environment similar to that of sample 8. samples 8 and 7 gave ages of 9.7 and 10.6 ky, respectively, i.e., an early holocene age (kaakinen et al. 2009). late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbard f. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd290 assemblage zone a5: astrononion gallowayi assemblage (samples 13 and 14) description. the sediment consists of a coarseningupward sequence of horizontally layered sand and gravel beds with frequently occurring shell fragments of hiatella arctica, astarte montagui, astarte borealis and mya truncata (unit 8; figs. 2, 3). sample 13 was collected from the lower 30 cm of the sedimentary unit, and sample 14 was from the middle part. astrononion gallowayi is the dominant species in both samples, and the most common accessory species are cassidulina reniforme (sample 13 only), cibicides lobatulus, elphidium albiumbilicatum, elphidium hallandense, elphidium excavatum f. clavata and haynesina orbiculare. compared with the underlying marine units, assemblage zone a5 is particularly characterized by its high content of astrononion gallowayi, by the absence of islandiella helenae in the lower sample and by a faunal diversity of 10, which is the highest in the entire record. palaeoenvironment and age. the dominance of astrononion gallowayi, particularly in the lower sample, combined with a relatively high faunal diversity, indicates a relatively stable salinity and a connection to the open ocean during deposition. as already mentioned, this species often occurs in association with cibicides lobatulus in high-energy, open-ocean shelf areas, and observations of high occurrences of astrononion gallowayi, together with cibicides lobatulus and elphidium albiumbilicatum, have been reported by rytter et al. (2002) from near coastal waters in iceland. the increase in abundance of the shallow-water species elphidium excavatum f. clavata and elphidium hallandense, together with cibicides lobatulus, towards the top of the section coincides with the coarsening upward of the sediments (see kaakinen et al. 2009), presumably reflecting an increase in the bottom current speed and a gradual lowering of the relative sea level as a result of isostatic rebound. the environmental indication of the assemblage of sample 14 is not much different from that of sample 13, but it might reflect a slight shallowing in water depth. this is in agreement with the interpretation by kaakinen et al. (2009) that this unit was deposited in upper shoreface and littoral environments, possibly during a falling sea level caused by isostatic rebound. samples 13 and 14 have been dated at 6.4 and 6.0 ky, respectively, i.e., mid-holocene (kaakinen et al. 2009). correlation and discussion the foraminiferal assemblages in the quaternary deposits from nordaustlandet are characterized by the dominance of arctic taxa, but there is a varying influence of a few sub-arctic species that may indicate temporary influence of slightly warmer water conditions in the area. generally, there is a high degree of similarity between the foraminiferal assemblage zones a1–a5 from murchisonfjorden and assemblages described from similar stratigraphic levels in other areas of svalbard. some variation can be expected, however, partly because of the poor preservation state of our assemblages and our unusual laboratory preparation techniques (see above), and partly because of the influence of different local environmental factors. thus, the number of species and specimens in the assemblages from nordaustlandet is lower than seen at most other sites from the region. this may be an indication of less favourable conditions in nordaustlandet than at the other sites, for instance caused by the relatively high influence of strong currents and/or occasional freshwater inflow from glaciers, but it may also be a result of the poor preservation state of the samples from nordaustlandet. however, glacier-proximal conditions, as characterized by a total dominance of either elphidium excavatum f. clavata and/or cassidulina reniforme (see nagy 1965; hansen & knudsen 1995; korsun et al. 1995; korsun & hald 2000), are not reflected by any of the assemblages from nordaustlandet. the correlation of assemblage zones a1–a5 at isvika, nordaustlandet, together with other foraminiferal assemblage zones from different sites in svalbard, are summarized in table 3. the following correlations are mainly focused on late quaternary onshore sites in svalbard. assemblage zones a1 and a2 assemblage zones a1 and a2 are both referred to the early weichselian. the depositional processes that formed the specimen-poor assemblage zone a2 are comparable with those responsible for the formation of modern residual assemblages in lag deposits in the barents sea (østby & nagy 1981). a comparison with other quaternary assemblages is difficult for this kind of assemblage, and the following correlation is therefore concentrated on the foraminifera-rich assemblage zone a1. generally, the age determinations of early weichselian deposits are not accurate enough to distinguish between different parts of the interval, and a correlation with assemblage zone a1 would therefore also include assemblage zone a2. shallow marine assemblages from the poolepynten site (fig. 1; table 3) on prins karls forland (unit a and unit c; bergsten et al. 1998) contain a similar type of species composition as found in assemblage zone a1 in isvika. unit a is characterized by a dominance of cassidulina late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbardf. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 291 reniforme, with astrononion gallowayi and elphidium excavatum as the most common accessory species. astrononion gallowayi is particularly abundant in the lower part of unit a, which is also characterized by a high faunal diversity. on the basis of the assemblage characteristics, and supported by amino acid dating, this part of the unit is considered to be eemian in age (bergsten et al. 1998), whereas the upper part of unit a and unit b are referred to the early weichselian. at the transition to unit b, there is an increase in elphidium albiumbilicatum and buccella frigida, and the composition of this unit is rather close to assemblage zone a1 at isvika, although elphidium albiumbilicatum is relatively more abundant in assemblage zone a1. the inferred ages for units a and c are 80 � 10 and 70 � 10 ky at prins karls forland, respectively (bergsten et al. 1998), corresponding to the ages obtained for assemblage zone a1 from isvika (mean age 79 ky). it has turned out, however, that osl ages are often underestimated by 10–14% (murray & funder 2003; murray et al. 2007), and sometimes by even up to 30–50% (larsen et al. 2009), and thus there is a possibility that the osl ages obtained for the assemblage zones at isvika may be too young. assemblage zones a1 and a2 correspond in time to zones fs-i and fs-ii at skilvika, at the mouth of bellsund (lycke et al. 1992) (fig. 1), and they may also correspond to assemblage zone fl-iv from linnéelva, near the mouth of isfjorden, western spitsbergen (lycke et al. 1992). these assemblages are dominated by cassidulina reniforme, elphidium excavatum and astrononion gallowayi, but the species astrononion gallowayi is relatively more frequent, and islandiella helenae and elphidium albiumbilicatum are less frequent at skilvika and linnéelva than in assemblage a1 at isvika. the overall environmental indication at these sites is, however, much alike, i.e., relatively shallow, open marine conditions with some influence of low-salinity waters, and maybe slightly ameliorated temperature conditions. thermoluminescence datings from skilvika gave ages of 89–105 ky. dating results of 87 and 118 ky b.p. at linnéelva may indicate a possible eemian age for that deposit. foraminiferal assemblages in zones f15 iv–f15 i from brøggerhalvøya (miller et al. 1989), further north in western spitsbergen (fig. 1), may correspond in time with assemblage zones a1 and a2 in isvika. the general compositions of the assemblages are similar, but a detailed correlation is not possible because of the difference in preservation state, presumably combined with slightly different local environments (see above). the age determination for assemblage zones f15 iv–f15 i (episode b) from brøggerhalvøya was 70 � 10 ky b.p., and the deposits are referred to the late part of mis 5. a foraminiferal assemblage found in early weichselian deposits from kongsfjordhallet on the opposite side of kongsfjorden (fig. 1), with non-finite 14c ages and luminescence ages of 75 � 10 and 91 � 9 ky (sivertsen 1996; houmark-nielsen & funder 1999), is remarkably similar to those described in assemblage zone a1 at isvika. table 3 correlation of the assemblage zones a1–a5 from isvika, nordaustlandet, with previously described foraminiferal assemblages from onshore sections and raised shoreline beach deposits in svalbard. isvika, assemblage zone (this study) chrono stratigraphy locality foraminiferal zone/ sedimentary unit author a5 mid-holocene kapp wijk talavera all samples all samples feyling-hanssen 1955 feyling-hanssen 1965 a4 late weichselian/early holocene skilvika linnéelva sarsbukta guldalen visdalen blåfjorddalen zone fs-iv zone fl-v zone qc entire record entire record entire record lycke et al. 1992 lycke et al. 1992 feyling-hanssen & ulleberg 1984 hansen & knudsen 1995 nagy 1984 landvik et al. 1992 a3 middle weichselian (mis 3) ? wijdefjorden region ? horizon 1 sharin et al. 2007 a1 and a2 early weichselian (mis 5a–5c) kongsfjordhallet poolepynten skilvika linnéelva brøggerhalvøya zone 1304-h; succession a unit a, upper part; unit c zones fs-i–fs-ii zone fl-iv zones f15 iv–f15 i; episode b sivertsen 1996; houmark-nielsen & funder 1999 bergsten et al. 1998 lycke et al. 1992 lycke et al. 1992 miller et al. 1989 ? eemian (mis 5e) poolepynten sarsbukta linnéelva unit a, lower part zone qb zones fl-i–fl-iii bergsten et al. 1998 feyling-hanssen & ulleberg 1984 lycke et al. 1992 late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbard f. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd292 assemblage zone 3 assemblage zone a3, which is dated to the middle weichselian, may correspond in time to horizon 1 described by sharin et al. (2007) from the wijdefjorden region in spitsbergen (fig. 1; table 3). the assemblage in horizon 1 is composed of small tests of only 10 species, dominated by the opportunistic species elphidium excavatum, and the horizon appears to have been deposited under unfavourable environmental conditions. unfortunately, sharin et al. (2007) do not provide any information on the detailed faunal composition, and the correlation of horizon 1 with the middle weichselian kapp ekholm interstadial (mangerud & svendsen 1992) is based solely on the fact that it is stratigraphically situated below the holocene. the probably middle weichselian assemblage from the wijdefjorden region (sharin et al. 2007), which lacks a proper age control because the age is inferred only on the basis of its relative stratigraphical position, is the only previously published description of foraminifera from onshore records in svalbard referred to that time interval. the present description of assemblage zone a3, with well-constrained osl and ams 14c age determinations, is thus the first description of a well-dated middle weichselian assemblage in the area. assemblage zone 4 assemblage zone a4 is early holocene in age and was deposited shortly after deglaciation. the assemblage is comparable with the late weichselian and early holocene zone qc, as described by feyling-hanssen & ulleberg (1984) from sarsbukta, spitsbergen (fig. 1; table 3). there is also a high degree of similarity to the late weichselian and early holocene assemblages in zone fs-iv from skilvika in bellsund (lycke et al. 1992), whereas the underlying zone fs-iii from skilvika represents a glacier-proximal assemblage with total dominance by elphidium excavatum f. clavata. similar glaciomarine deposits are also found in zone fl-v at linnéelva. all these zones are late weichselian to early holocene in age. there is a close resemblance between assemblage zone a4 at isvika and the foraminiferal species composition in zones g7a, g7b, g7c, g5a and g5b from guldalen, edgeøya (hansen & knudsen 1995), and part of the marine sequence at visdalen, edgeøya (nagy 1984). other foraminiferal zones from guldalen and visdalen, as well as those from blåfjorddalen, edgeøya (landvik et al. 1992), contain different species compositions because of local differences in the palaeoenvironments. the palaoenvironmental indications of assemblage zone a4 (table 2) is in agreement with the findings of mytilus edulis, a species that has been linked with ameliorated temperature conditions and slightly reduced salinity in early holocene deposits in the murchisonfjorden area (blake 2006). assemblage zone 5 assemblage zone a5 at isvika corresponds in time to some rather diverse holocene assemblages from talavera, which indicate ameliorated temperature conditions, and were referred to the holocene warm interval by feyling-hanssen (1965). the environmental indication of the isvika assemblages is considerably less favourable than for the talavera assemblages, presumably because of the influence of relatively colder water masses in the isvika area. the high abundance of astrononion gallowayi at both sites is particularly remarkable. as also pointed out by bergsten et al. (1998), similar high abundances as found in the holocene are not yet seen in modern foraminiferal faunas. another less diverse mid-holocene fauna has been presented from shore terraces at kapp wijk in isfjorden by feyling-hanssen (1955a), but at that site, the species astrononion gallowayi was not mentioned. the species composition in assemblage zone a5 is rather close to that in zone qc from sarsbukta, which is rich in astrononion gallowayi (feyling-hanssen & ulleberg 1984), even though zone qc is late weichselian/early holocene in age. it is interesting to note that assemblages from onshore records of svalbard, which are referred to the eemian interglacial, are often characterized by a high abundance of astrononion gallowayi. this is, for instance, seen for the lower part of unit a at poolepynten (bergsten et al. 1998), zone qb at sarsbukta (feyling-hanssen & ulleberg 1984) and zones fl-1–fl-3 at linnéelva (lycke et al. 1992). it is notable that only a few mid-holocene marine deposits have been reported from onshore sections of svalbard. data from raised shoreline and beach deposits with mytilus edulis, indicating deposition during the holocene thermal optimum, are, however, reported from several sites by feyling-hanssen (1955b), hjort et al. (1995), salvigsen (2002) and blake (2006), among others. sea level and glaciations the timing and palaeoenvironmental interpretations for assemblage zones a1–a5 (table 2) from nordaustlandet are compared with the eustatic sea-level curve by waelbroeck et al. (2002), and with the time–distance curve for the glaciations in svalbard by svendsen et al. (2004). although the exact timing of the onset and termination of weichselian glaciations in the area is not well late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbardf. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 293 determined, the marine intervals clearly correlate with periods of high global sea-level stand during interstadial/ interglacial conditions (fig. 4). koç et al. (2002) state that hinlopenstretet was covered by a grounded glacier allowing no water exchange through the strait during the late weichselian. the sea level was around 120 m lower during that time than at present (fig. 4; waelbroeck et al. 2002). according to blake (2006), marine waters first entered murchisonfjorden at the younger dryas–holocene transition. this corresponds in time to the first indication of relatively warm atlantic water inflow into hinlopenstretet from the north (see koç et al. 2002; ślubowska et al. 2005; ślubowska-woldengen et al. 2007). this inflow, combined with the increase in insolation (see ślubowska et al. 2005), probably resulted in increased melting of the glaciers on nordaustlandet, and a subsequent large meltwater run-off into the shallow murchisonfjorden, as indicated by the foraminiferal assemblage a4 as well as the occurrence of mytilus edulis in the deposits. conclusions this study shows that the coastal area of the northwestern part of nordaustlandet, svalbard, was inundated by the sea (ice free) during at least three, presumably relatively short, intervals of the weichselian, as well as during a major part of the holocene. the five late quaternary foraminiferal assemblage zones a1–a5 from murchisonfjorden, nordaustlandet, all represent glacier-distal, inner-shelf environments with connection to the open ocean, but with some differences in bottom-current velocity and in salinity (table 2). the few foraminiferal samples in the present material gave a general overview of the environment for each assemblage zone, but changes within each zone could not be determined, except for the holocene. it has not been possible to pinpoint the exact timing of the samples within each marine interval of the weichselian, but they most likely derive from the middle or late stages of the interstadials. because of high abundances of arctic species throughout the late quaternary in svalbard, it is difficult to fig. 4 correlation of the late quaternary foraminiferal assemblage zones a1–a5 on nordaustlandet with the eustatic sea-level curve of waelbroeck et al. (2002), the time– distance curve of the western barents sea ice sheet in its northern extension over svalbard (svendsen et al. 2004) and marine isotope stages (mis 5–1). grey shading indicates the marine intervals in murchisonfjorden (transitions are graded because the exact timing of the onset and termination of glaciations in the area is not well established). horizontal grey lines mark the optically stimulated luminescence and accelerator mass spectrometry 14c mean ages (ky) of marine samples. late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbard f. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd294 determine if sediments were deposited during an interglacial or an interstadial. a comparison of assemblage zones a1–a5 from isvika with previously described onshore sections and raised shoreline deposits from the weichselian and the holocene shows that there are some important characteristic features for the assemblages in each of the stratigraphic intervals in the area, but also that there are considerable variations as a result of the influence of different local environmental factors. the marine intervals in nordaustlandet (assemblage zones a1–a5) clearly correlate with periods of high global sea-level stand during interstadial/interglacial conditions. acknowledgements our thanks go to dorthe reng erbs-hansen for assistance with the foraminiferal determinations, to neil rees for improving the language of the paper and to weston blake jr for reading and commenting on earlier versions of the manuscript, and for improving the language. we are grateful to the journal’s subject editor and to the two reviewers for valuable comments and corrections to the manuscript. this study was financed by the academy of finland (project no. 1116709), and is a contribution to the multidisciplinary international polar year (ipy) activity entitled ipy-kinnvika (ipy 2007-08 project no. 58). references andersen e.s., dokken t.m., elverhøi a., solheim a. & fossen i. 1996. late quaternary sedimentation and glacial history of the western svalbard continental margin. marine geology 133, 123–156. bergsten h., andersson t. & ingólfsson ó. 1998. foraminiferal stratigraphy of raised marine deposits, representing isotope stage 5, prins karls forland, western svalbard. polar research 17, 81–91. blake w. jr. 1961. radiocarbon dating of raised beaches in nordaustlandet, spitsbergen. in g.o. raasch (ed.): the geology of the arctic. pp. 133–145. toronto: university of toronto press. blake w. jr. 1962. geomorphology and glacial geology in nordaustlandet, spitsbergen. phd thesis, department of geology, ohio state university. blake w. jr. 1981. glacial history of svalbard and the problem of the barents shelf ice sheet: comments. boreas 10, 125–131. blake w. jr. 2006. occurrence of the mytilus edulis complex on nordaustlandet, svalbard: radiocarbon ages and climatic implications. polar research 25, 123–137. donner j.j. & west r.g. 1957. the quaternary geology of brageneset, nordaustlandet, spitsbergen. norsk polarinstitutt skrifter 109. oslo. norwegian polar institute. donner j.j. & west r.g. 1995. fluctuations of the vestfonna ice margin at brageneset, nordaustlandet, svalbard, after the last glacial maximum. bulletin of the geological society finland 67, 29–36. ellis b.f. & messina a. 1949. catalogue of foraminifera. with supplements up to 2007. new york: american museum of natural history/micropaleontology press. elverhøi a., liestøl o. & nagy j. 1980. glacial erosion, sedimentation and microfauna in the inner part of kongsfjord, spitsbergen. in: geological and geophysical research in svalbard and on jan mayen, 1980. norsk polarinstitutt skrifter 172. pp. 33–61. oslo: norwegian polar institute. feyling-hanssen r.w. 1955a. late pleistocene deposits at kapp wijk, vestspitsbergen. norsk polarinstitutt skrifter 108. oslo: norwegian polar institute. feyling-hanssen r.w. 1955b. stratigraphy of the marine late-pleistocene of billefjorden, vestspitsbergen. norsk polarinstitutt skrifter 107. oslo: norwegian polar institute. feyling-hanssen r.w. 1965. shoreline displacement in central vestspitsbergen and a marine section from the holocene of talavera on barentsøya in spitsbergen. norsk polarinstitutt meddelelser 93. oslo: norwegian polar institute. feyling-hanssen r.w. 1972. the foraminifer elphidium excavatum (terquem) and its variant forms. micropaleontology 18, 337–354. feyling-hanssen r.w., jørgensen j.a., knudsen k.l. & lykke-andersen a.-l. 1971. late quaternary foraminifera from vendsyssel, denmark, and sandnes, norway. bulletin of the geological society of denmark 21, 67–367. feyling-hanssen r.w. & ulleberg k. 1984. a tertiary– quaternary section at sarsbukta, spitsbergen, svalbard and its foraminifera. polar research 2, 77–106. hald m., ebbesen h., forwick m., godtliebsen f., khomenko l., korsun s., olsen l.r. & vorren t.o. 2004. holocene paleoceanography and glacial history of the west spitsbergen area, euro-arctic margin. quaternary science reviews 23, 2075–2088. hald m. & korsun s. 1997. distribution of modern benthic foraminifera from fjords of svalbard, european arctic. journal of foraminiferal research 27, 101–122. hald m. & korsun s. 2008. the 8200 cal. yr bp event reflected in the arctic fjord, van mijenfjorden, svalbard. the holocene 18, 981–990. hald m., steinsund p.i., dokken t., korsun s., polyak l. & aspeli r. 1994. recent and late quaternary distribution of elphidium excavatum forma clavata in arctic seas. cushman foundation special publication 32, 141–153. hansen a. & knudsen k.l. 1995. recent foraminiferal distribution in freemansundet and early holocene stratigraphy on edgeøya, svalbard. polar research 14, 215–238. haynes j.r. 1973. cardigan bay recent foraminifera. bulletin of the british museum (natural history) zoology, supplement 4. london: british museum. hjort c., mangerud j., adrielsson l., bondevik s., landvik j.y. & salvigsen o. 1995. radiocarbon dated common late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbardf. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 295 mussels mytilus edulis from eastern svalbard and the holocene marine climatic optimum. polar research 14, 239–243. houmark-nielsen m. & funder s. 1999. pleistocene stratigraphy of kongsfjordhallet, spitsbergen, svalbard. polar research 18, 39–49. hyvärinen h. 1969. trullvatnet: a flandrian stratigraphical site near murchisonfjorden nordaustlandet, spitsbergen. geografiska annaler series a 51, 42–45. hyvärinen h. 1970. flandrian pollen diagrams from svalbard. geografiska annaler, series a 52, 213–222. ingólfsson ó., røngvaldsson f., bergsten h., hedenäs l., lemdahl g., lirio j.m. & sejrup h.p. 1995. late quaternary glacial and environmental history of kongsøya, svalbard. polar research 14, 123–141. jennings a.e. & helgadóttir g. 1994. foraminiferal assemblages from the fjords and shelf of eastern greenland. journal of foraminiferal research 24, 123–144. jennings a.e., weiner n.j., helgadóttir g. & andrews j.t. 2004. modern foraminiferal faunas of the southwestern to northern iceland shelf: oceanographic and environmental controls. journal of foraminiferal research 34, 180–207. kaakinen a., salonen v.-p., kubischta f., eskola k.o. & oinonen m. 2009. weichselian glacial stage in murchisonfjorden, nordaustlandet, svalbard. boreas 38, 718–729. knudsen k.l. 1978. middle and late weichselian marine deposits at nørre lyngby, northern jutland, denmark, and their foraminiferal faunas. danmarks geologiske undersøgelse series b 112, 1–44. knudsen k.l. 1998. foraminiferer i kvartaer stratigrafi: laboratorieog fremstillingsteknik samt udvalgte eksempler. (foraminifera in quaternary stratigraphy: laboratory and presentation techniques as well as selected examples.) geologisk tidsskrift 3, 1–25. koç n., klitgaard-kristensen d., hasle k., forsberg c.f. & solheim a. 2002. late glacial paleoceanography of hinlopen strait, northern svalbard. polar research 21, 307–314. korsun s. & hald m. 2000. seasonal dynamics of benthic foraminifera in a glacially-fed fjord of svalbard, european arctic. journal of foraminiferal research 30, 251–271. korsun s., hald m., khomenko l., forwick m., yoon h.-i. & nam s.-i. 2006. holocene paleoceanography of an arctic fjord of svalbard as recorded by stable isotopes, foraminifera and macrofauna. anuário do instituto de geociências—ufrj 29, 595–596. korsun s., pogodina i.a., forman s.l. & lubinski d.j. 1995. recent foraminifera in glaciomarine sediments from three arctic fjords of novaja zemlja and svalbard. polar research 14, 15–31. landvik j.y., hansen a., kelly m., salvigsen o., slettemark ø. & stubdrup o.p. 1992. the last deglaciation and glacimarine/marine sedimentation on barentsøya and edgeøya, eastern svalbard. lundqua report 35, 61–83. larsen n.k., krohn c.f., kronborg c., nielsen o.b. & knudsen k.l. 2009. lithostratigraphy of the late saalian to middle weichselian skærumhede group in vendsyssel, northern denmark. boreas 38, 762–786. lønne i. & mangerud j. 1991. an early or middle weichselian sequence of proglacial, shallow marine sediments on western svalbard. boreas 20, 85–104. lutze g.f. 1965. zur foraminiferen-fauna der ostsee. (on the foraminiferal fauna of the baltic sea.) meyniana 15, 75–142. lycke a.k., mangerud j. & sejrup h.p. 1992. late quaternary foraminiferal stratigraphy from western svalbard. boreas 21, 271–288. majewski w., szczuciński w. & zajaczkowski m. 2009. interactions of arctic and atlantic water-masses and associated environmental changes during the last millennium, hornsund (sw svalbard). boreas 38, 529–544. mangerud j., bondevik s., ronnert l. & salvigsen o. 1992. shore displacemnt and marine limits on edgeøya and barentsøya, eastern svalbard. lundqua report 35, 51–60. mangerud j., dokken t., hebbeln d., heggen b., ingólfsson ó., landvik j.y., mejdahl v., svendsen j.i. & vorren t.o. 1998. fluctuations of the svalbard–barents sea ice sheet during the last 150 000 years. quaternary science reviews 17, 11–42. mangerud j. & svendsen j.i. 1992. the last interglacial– glacial period on spitsbergen, svalbard. quaternary science reviews 11, 633–664. miller g.h., sejrup h.p., lehman s.j. & forman s.l. 1989. glacial history and marine environmental change during the last interglacial–glacial cycle, western spitsbergen, svalbard. boreas 18, 273–296. murray a.s. & funder s. 2003. optically stimulated luminescence dating of a danish eemian coastal marine deposit: a test of accuracy. quaternary science reviews 22, 1177–1183. murray a.s., svendsen j.i., mangerud j. & astakhov v. 2007. testing the accuracy of quartz osl dating using a known-age eemian site on the river sula, northern russia. quaternary geochronology 2, 102–109. murray j.w. 1991. ecology and palaeoecology of benthic foraminifera. harlow: longman scientific and technical. murray j.w. 2006. ecology and application of benthic foraminifera. cambridge: cambridge university press. nagy j. 1984. quaternary glaciomarine deposits and foraminifera from edgeøya, svalbard. boreas 13, 319–332. nagy j. 1965. foraminifera in some bottom samples from shallow waters in vestspitsbergen. norsk polarinstitutt årbok 1963, 109–126. østby k.l. & nagy j. 1981. foraminiferal distribution in the western barents sea, recent and quaternary. polar research 1, 53–95. rasmussen t.l., thomsen e., ślubowska m.a., jessen s., solheim a. & koç n. 2007. paleoceanographic evolution of the sw svalbard margin (76°n) since 20 000 14c yr bp. quaternary research 67, 100–114. late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbard f. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd296 rytter f., knudsen k.l., seidenkrantz m.-s. & eiríksson j. 2002. modern distribution of benthic foraminifera on the north icelandic shelf and slope. journal of foraminiferal research 32, 217–244. salvador a. 1994: international stratigraphical guide—a guide to stratigraphic classification, terminology and procedure. boulder: geological society of america. salvigsen o. 2002. radiocarbon-dated mytilus edulis and modiolus modiolus from northern svalbard: climatic implications. norsk geografisk tidsskrift 56, 56–61. sharin v.v., alekseev v.v., dymov v.a., pogodina i.a., bol’shiyanov d.y. & gusev e.a. 2007. new data on the late quaternary stratigraphy and paleogeography of the wijdefjorden region (west spitsbergen). doklady earth sciences 413, 822–824. sivertsen j. 1996. pleistocæn foraminiferstratigrafi og paleoøkologi i hœvede kystklinter på kongsfjordhallet nv spitsbergen. (pleistocene foraminiferal stratigraphy and palaeoecology in raised coastal cliffs on kongsfjordhallet, north-west spitsbergen.) master’s thesis, aarhus university. ślubowska m.a., koç n., rasmussen t.l. & klitgaard-kristensen d. 2005. changes in the flow of atlantic water into the arctic ocean since the last deglaciation: evidence from the northern svalbard continental margin, 80°n. paleoceanography 20, pa4014, doi: 10.1029/2005pa001141. ślubowska-woldengen m., rasmussen t.l., koç n., klitgaard-kristensen d., nilsen f. & solheim a. 2007. advection of atlantic water to the western and northern svalbard shelf since 17,500 cal yr bp. quaternary science review 26, 463–478. steinsund p.i. 1994. benthic foraminifera in surface sediments of the barents and kara seas: modern and late quaternary applications. phd thesis, university of tromsø. svendsen j.i., elverhøi a. & mangerud j. 1996. the retreat of the barents ice sheet on the western svalbard margin. boreas 25, 244–256. svendsen j.i., gataullin v., mangerud j. & polyak l. 2004. the glacial history of the barents and kara sea region. in j. ehlers & p.l. gibbard (eds.): quaternary glaciations— extent and chronology. pp. 369–378. amsterdam: elsevier. svendsen j.i. & mangerud j. 1992. paleoclimatic inferences from glacial fluctuations on svalbard during the last 20 000 years. climate dynamics 6, 213–220. waelbroeck c., labeyrie l., michel e., duplessy j.c., mcmanus j.f., lambeck k., balbon e. & labracherie m. 2002. sea-level and deep water temperature changes derived from benthic foraminifera isotopic records. quaternary science review 21, 205–305. walton w.r. 1964. recent foraminiferal ecology and paleoecology. in j. imbrie & n.d. newell (eds): approaches to paleoecology. pp. 151–237. new york: john wiley and sons. wollenburg j.e., kuhnt w. & mackensen a. 2001. changes in arctic ocean paleoproductivity and hydrography during the last 145 kyr: the benthic foraminiferal record. paleoceanography 16, 65–77. late quaternary foraminiferal record in murchisonfjorden, nordaustlandet, svalbardf. kubischta et al. polar research 29 2010 283–297 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 297 editorial with this issue, polar research has gone over to a double-column layout more in line with today’s international publication standards. basic edi torial policy remains unchanged. the expansion of the scientific information sys tem has resulted in the introduction of new tech niques of information transmission. readers need to obtain and identify published material as quickly as possible. therefore, all abstracts in polar research include full bibliographic identi fication. a page biblid will be added at a later stage to facilitate identification of photocopied single pages from an article. such page identifi cation has proved to be of more value to the users of a journal than the conventional running head. the present issue of polar research begins vol. 1, no. 1 of a new series. this is in accordance with the general lines of international reference and abstracting services and ensures that research published in previous and future issues is readily obtainable. as well as containing complete source and citation details, title pages have the norsk polarinstitutt logotype providing instant identi fication of coverless offprints. norsk polarinstitutt october 1983 the geology and age of peter i q)y, antarctica t o r e prestvik and robert a. duncan prestvik, t. & duncan, r. a,: the geology and age of peter i oy, antarctica. polar research 9 ( 2 ) , 89 98. the island peter i 0 y is located in the bellinghausen sea 400 km off the coast of west antarctica. it is situated at the transition between oceanic and contintental crust close t o a former transform fault, the tharp fracture zone. the island is completely volcanic, consisting of predominantly alkali basalt and hawaiite and some more evolved rocks. sampling done by the aurora expedition in 1987 has made dating and detailed petrological studies possible. the island appears to be much younger (<0.5 ma) than previously believed. however, the volcanic activity responsible for this oceanic island may have lasted for 10-20 ma. volcanic activity at the island thus took place at the same time as post-subduction rift-related volcanism took place along the antarctic peninsula and in marie byrd land. however, the petrologic data indicate that this may be coincidental and that the peter i 0 y activity is independent and related t o transtensional rifting along the tharp fracture zone. tore prestoik, department of geology and mineral resources engineering, university of trondheim, n 7034 trondheim, norway; robert a. duncan, college of oceanography, oregon state uniuersiry, coruallis, oregon 97331, usa. introduction peter i 0 y is located at 68"50's, 98"35'w in the bellinghausen sea approximately 400 km north east of eights coast, west-antarctica (fig. 1). the island was discovered and named by the russian uon bellinghausen expedition in 1821. it became norwegian territory after the first landing was made by the noruegia expedition in 1929. the most comprehensive reports on early expeditions to the island can be found in the papers by broch (1927), johnson (1966), and bastien & craddock (1976a). the norwegian aurora expedition visited peter i 0 y from 23 january to 2 february 1987 under very good weather and ice conditions (fig. 2 ) . the present account, which is based on samples collected during this expedition, reports new geochronological data and gives a review of the geology of this remote island. detailed petro logical and geochemical descriptions will be pub lished elsewhere (prestvik et al. 1990). whereas the samples described by broch (1927) were all dredged off the island, and the samples examined by bastien & craddock (1976a) came from one locality on the western coast, the aurora collection comprises material from five different locations on the island (fig. 3): (1) fram nmodden and (2) kapp ingrid/norvegiabukta on the western coast, (3) tvisteinen and (4) aur oraholmen in the north, and ( 5 ) michajlovodden on the eastern coast of the island. the aurora collection contains various types of basalts. in addition to this material prestvik et al. (1990) reexamined the dredged odd-i collection (broch 1927), and three of these samples were included in their study. because no geologists participated in the aurora expedition, some of the geological features and field relations described here are based on previously published information. tectonic setting and geologic history peter i 0 y is 19 x 13 km in n-s/e-w directions, it reaches 1640m above sea level (fig. 3) and covers an area of approximately 154 km2 (norsk polarinstitutt 1988). it is the surface part of a huge volcanic structure rising from about 4,000 m below sea level between the south pacific ocean floor and the upper continental rise of the ant arctic continent (tucholke & houtz 1976; kimura 1982). peter i 0 y thus classifies as an oceanic island. it is not known with certainty whether the volcanic structure represents hawaiian type within-plate activity, or if it is related to ''leakage'' along zones of tectonic weakness, such as a trans 90 t . prestvik & r . a . duncan weddell sea a l e x a n d e r e i g h t s c o a s t marie b y r d l a n d fig. 1. location map of peter i 0 y with major tectonic features of the southeasternmost pacific indicated form fault. herron & tucholke (1976) found that peter i 0 y was located close t o a former transform fault or fracture zone, although its relation t o the tectonic history of the south pacific in the area was not fully understood then. however, on the basis of several more recent reports (weissel et al. 1977; barker 1982; cande et al. 1982: kimura 1982; stock & molnar 1987), it seems well-estab lished that this part of the continental margin of west antarctica was a collisional plate boundary during most of the cretaceous and into early tertiary. at that time oceanic crust formed at an oceanic ridge which is now subducted beneath the continental crust of west antarctica. between the geology and age of peter i cay, antarctica 91 fig. 2. aerial view of peter i 0 y f r o m t h c n o r t h (photo: n o r s k polarinstitutt). the tharp (peter i fracture zone of kimura 1982) and tula fracture zones (fig. 1). this subduction stopped some time in the middle eocene (weissel et al. 1977: barker 1982; cande et al. 1982). kimura (1982) reported the existence of trench and fore-arc basin sediment complexes within the continental rise/slope part of the presently passive oceanic/continental margin. from this evidence it can be inferred that peter i 0 y is situated on oceanic crust covered with 1.5-2 km of various kinds of sediments. the age of peter i 8 y has not been known in detail, because only one k/ar date (12.5 2 1.5ma) of a basaltic lava from the island has been published (bastien & craddock 1976a). this age determination indicates that the vol canism of this area may have started back in early miocene or late oligocene. our new k/ ar measurements of peter i 8 y rocks indicate, however, that the activity responsible for the rocks at the surface is much younger, <0.5 ma (see below). the volume of the total volcanic cone above the seafloor can be estimated on the basis of bathymetric data (bastien & craddock 1976a) to be about 2,900 km3. because eruption rates are unknown, it is difficult to estimate when the peter i 8 y volcanism started. however, i f we as an example select eruption rates 1&20% of those of the very productive hawaiian plume (clague & dalrymple 1987), the building up of the peter i 8 y cone may have started 1&20 ma before present time. (higher or larger rates expand the age range on the lower and higher sides of this estimate respectively). based on this estimate, the volcanic activity of the peter i 0 y area thus coincides more or less completely with the rift-related volcanism in marie byrd land and eights coast (lemasurier & rex 1982) and along the antarctic peninsula (smellie et al. 1988). geological features and petrology broch (1927) described the samples dredged off peter i 8 y during the odd i expedition, and holtedahl (1935) made some points on the geo logy on the basis of photographs and samples taken during the norvegia expedition in 1929. accounts of t h e geology have also been given by johnson (1966) and bastien & craddock (1976a. b). and rowley (1989) has reviewed the geology of the island. the most comprehensive 92 t. prestoik & r . a . duncan peter i oy e v a o d d e n 1 n 60o45‘ i 6 8 o s o ’ s 6 8 o 5 5 ‘ scale u 5 k m 90o40’ 9 o 0 3 0 ’ w fig. 3 . sketch map of peter 1 0 y showing sample localions (norsk polarinstitutt 1988. modified) contributions are those of broch (1927). bastien & craddock (1976a). and prestvik et al. (1990). broch (1927) described in great detail the pet rography of 175 rock samples dredged close to the western coast of the island. the material collected i n norvegiabukta during the burton island expedition in 1960 (craddock & hubbard 1961; bastien & craddock 1976a) comprises 29 samples. thirteen of these are basalts, the rest are trachyandesites (trachyte according to prestvik et al. 1990). one of the basalts and most of the trachyandesites (trachytes) have inclusions of gabbro/diorite (bastien & craddock 1976a). these authors described the geology at nor vegiabukta as made up of interbedded flows of basalt and more siliceous (trachyte) lava. these the geology and age of peter i @ y , antarctica 93 are intruded by dikes and small stocks. plug-like masses of basalt were described from evaodden in the north, from kapp ingrid, and from the southeast corner of sandefjordbukta (fram nzsodden). broch (1927) also described xeno lithic material in trachyandesite (trachyte) from norvegiabukta, and he inferred ( p . 34) the exist ence of a light-colored intrusion within the flow sequence at kapp ingrid. on the basis of excellent photographs taken from helicopter during the aurora expedition, we are adding the following information on geo logical features: at least 95% of the island is covered by per manent ice and snow. a flat summit area (fig. 3) indicates the presence of a summit crater. the exposed cliffs along the northern part of the west coast present a considerable section through the volcanic pile of the island. there lava flows, flow units, fragmental rocks (probably hyaloclastites) and dikes are well-exposed in cliffs reaching from sea-level and up to about 400m. the asym metrical shape of the island, with the assumed crater closer to the west coast, indicates that the lowermost lavas exposed along the western coast could represent some of the oldest activity of fig. 4. thin lava flows or flow units at the kapp ingrid promontory. the uppermost section appears to contain fragmental (pyroclastic) material. the summit reaches 163 m above sea-level. (photo: norsk polarinstitutt). 94 t . prestvik & r . a . duncan fig. 5 . the islet of tvistrinen. massive basalt is capped by thin flow units. the top of the islet is 49 rn abovc sea-level. (photo: n o n k polarinstitutt) the island. the best exposures appear to be a t framnzsodden. kapp ingrid and at narveg iabukta (fig. 3). photographs show massive lava overlaid by thin lava flows or flow units (fig. 4) at both f r a m n m o d d e n and a t the outer part of the promontory kapp ingrid. pictures of the small islet tvisteinen in the very north of the island (fig. 3) leave a similar impression: thin lava flows occur on t o p of much thicker dense lava flows (fig. 5). it is possible that the dense lavas a r e more resistant to abrasion and that their presence at these locations is the reason why kapp ingrid and framnzsodden still exist as promontories. however. at norvegiabukta k a p p ingrid is almost cut off from the mainland, and it is probable that kapp ingrid in the future will be separated from the rest of t h e island. tvisteinen (fig. 3) may represent a remnant of such a promontory in the north (from evaodden) because abrasion has reached a more advanced stage there. prestvik e t al. (1990) described the petrology and geochemistry of peter i 8 y on the basis of the aurora collection and on reexamination of a few samples of the odd i collection. analytical data of representative samples a r e presented in table 1. t h e results of prestvik e t al. (1990) may be summarized as follows: the rocks of the island a r e predominantly alkali the geology and age of peter i 0 y , antarctica 95 table 1. major (in wt.%) and trace element (in ppm) data for representative peter i 0 y samples. pi-2 pi-4 pi-13 1-19 1-13 alk.basalt alk.basalt alk.basalt benmoreite trachyte 47.64 3.32 13.67 2.25 9.36 0.14 8.81 9.04 3.32 1.23 0.61 0.78 46.32 3.72 13.37 2.45 9.43 0.15 8.88 9.10 3.76 1.37 0.62 0.63 49.22 3.10 14.71 2.31 9.00 0.14 6.12 9.20 3.35 0.93 0.49 1.69 57.22 2.32 15.01 '8.36 0.10 3.65 5.35 4.86 2.84 0.44 0.70 62.18 0.87 16.90 '4.81 0.05 1.38 2.50 7.55 3.58 0.22 0.53 total 100.17 99.80 100.26 100.85 100.57 ba rb sr zr y nb sc cr ni co v la ce nd sm eu gd tb yb lu ta hf th u 29 1 7 14 279 30.1 48 19.7 281 229 47 177 37.1 101 41.6 9.2 2.76 6.79 0.88 1.08 0.13 3.1 5.6 < i .8 0.86 21.4 311 736 287 29.7 44 21.1 350 228 57 187 39.1 113 42.9 9.5 3.14 5.33 0.81 1.13 0.12 3.36 6.87 2.93 0.77 22.3 212 550 219 29.5 29 22.0 155 99 44 175 28.0 94 31.2 7.7 2.84 4.73 1.01 1.33 0.20 2.31 5.03 2.57 1.14 22.4 432 573 453 31.7 48 11.4 97 84 31 123 54.5 117 45.8 9.4 2.79 1.06 1.56 0.22 3.76 10.84 14.49 3.35 66.8 n.d. 618 1,125 548 15.2 95 3.1 21 13 <3.6 38 73.5 159 66.9 10.6 66.5 3.15 0.77 0.52 0.07 6.65 13.13 15.19 4.26 n.d. * = total fe as feo. n.d. = not determined basalt and hawaiite, some benmoreite and trach yte. the basic rocks typically contain phenocrysts of olivine, minor diopsidic augite, and in one sample plagioclase. small xenoliths in basalt com prise mantle-type spinel iherzolite, cumulate cli nopyroxenite and gabbro and colourless felsic inclusions that consist of medium-grained, strained quartz, plagioclase, and abundant colourless glass. chemically, the basic rocks are characterized by rather high mgo (7.8 10.2 wt.%) and tioz (3.1-3.7 wt.%) and rela tively low cao (8.4-9.5 wt.%) contents. they have steep ree patterns [(la/yb), = 201 with hree only 5x chondrite. y and sc are almost constant at relatively low levels. compatible trace elements such as ni and cr show considerable variation (190-300 and 150-470 ppm resp.), whereas v shows only little variation. sr and nd isotope ratios vary slightly with s7sr/86sr aver aging 0.70388 and 143nd/'44nd 0.51277, both typical for ocean island volcanism. lead isotope ratios are consistently high in basalts; z06pb/ ?04pb = 19.194, zo7pb/204pb = 15.728, and '08pb/ 204pb = 39.290, whereas benmoreite is somewhat less radiogenic. oxygen isotope analyses average 6l80 = +6.0%0. incompatible trace elements vary 96 t . prestuik & r . a . duncan by a factor of 1.5-2.0 within the range of the basic rocks. it is proposed that the incompatible trace element variations represent different degrees (7-15%) of partial melting, and that these melts were later modified by minor olivine and spinel fractionation. the very small variation in y (and sc) and the very fractionated r e e pattern indi cate that the source had a y and hree-rich residual phase. most probably garnet. further more, on the basis of chemical composition and available experimental data (falloon & green 1988), prestvik et al. (1990) suggested that the source was slightly hydrous and that melting took place at 1.8-2.0gpa. trachyte was derived by multiphase fractionation of ne-normative basalts, and benmoreite from hy-normative parental liquids. geochronology k-ar analyses were performed to determine the age and duration of volcanic activity at peter i 0 y . samples were selected to cover the widest possible geographic distribution, and from the freshest material available. all samples chosen for age determinations were basaltic and con tained small amounts of olivine phenocrysts. these rocks were massive, well-crystallized and completely fresh. any small xenocrystic material table 3. k-ar determinations for basalts from peter i 0 y . was avoided because of the possibility of inherited mantle argon. samples were first crushed and sieved to obtain the 0.5 to 1 mm size fraction; any surface weath ering, saw marks or xenocrystic material was removed. the crushed material was washed in distilled water to remove dust and then dried. these samples were then split into two aliquots, one for k-analysis by atomic absorption spectro photometry and the other for ar-analysis by mass spectrometry. from 3 to 5 g of the crushed fraction of each sample was loaded in a suspended mo-crucible in the argon extraction line and baked overnight at 180°c to achieve high vacuum (-10-6pa). the samples were fused by radio frequency heating of the crucibles and active gases were gettered over hot ti-ti02 metal sponge. the isotopic com position of argon (40ar, 36ar) was then measured with an aei ms-10s mass spectrometer. because of the expected young ages and low amounts of radiogenic argon, several special analytical pro cedures were adopted, following cassignol & gil lot (1982). first, the usual addition of a known quantity of 3xar to calibrate sensitivity was elim inated because of small amounts of 40ar and 36ar in the spike; sensitivity was determined from the long-term measurement of conventional, spiked analyses which showed only a 1-270 variation in ”ar peak heights. secondly, pipetted aliquots of sample location k content radiogenic “’ar radiogenic ‘“ar/ age” ? lo ( k a ) ( w t . % ) ( x mol/g) total “‘ar pi-? north beach at 1.117 0.21433 0.036 kapp ingrid: massive lava massive lava grey lava grcy lava with rare pcridotite xenoliths kapp ingrid; massive lava pi-7 n o n q i a b u k t a : 1.291 0 39812 0.068 pi-13 michajlovodden: 1.223 0.61848 0.062 pi-15 auroraholmen: 1.241 0.5 1 768 0.052 pi-23 north beach at 1.164 0.66084 0.052 1 1 1 + 36 178 ? 20 292 t 49 2 2 9 t 13 327 t 88 * ages calculated using the following decay constants: a, = 0.581 x 10-’o/a: a, = 4.962 x 10-i0/a; “k/k = 1.167 x to-‘ mol/ the k-ar determinations were performed at oregon state university. u s a . mol. the geology and age of peter i 0 y , antarctica 97 has stopped, lithospheric subsidence is the normal process. air argon were routinely measured both before and after each sample analysis in order to obtain the most precise correction for atmospheric 40ar as possible. proportions of radiogenic “ar as small as a few tenths of one percent of the total 40ar signal were, thus, detectable and repro ducible (levi et al. 1990; gillot & nativel 1989). measured ages fall in the range from 100,000 to 300,000 years (table 2) for these basaltic rocks. analytical uncertainties ( l a ) vary from 6 to 32% of the measured age, depending on the proportion of radiogenic 40ar. there is no apparent spatial variation in ages: samples from the eastern (pi 13) and northern (pi-15) coasts fall in the same range as the three basalts from the kapp ingrid section (pi-2, pi-7, and pi-23). hence, the island was built up above sea-level in late pleistocene time, probably entirely within the brunhes epoch of normal magnetic polarity. summary the rocks of peter i 0 y are generally of the same type and age as those outcropping in extensional regimes on the nearby continent, and these occur rences may therefore be related to each other in some way. however, the peter i 0 y rocks are considerably more radiogenic in sr and less in nd than the rocks of the antarctic peninsula and marie byrd land which have morb-type isotope characteristics. according to prestvik et al. (1990) possible explanations are that peter i 0 y rep resents separate asthenospheric hot spot activity, or is connected to transtensional rifting along the old fractures of the tharp fracture zone as subduction ceased in early tertiary. the previously reported k-ar age of 12.5 ? 1.5 ma for a basalt from kapp ingrid/ norvegiabukta (bastien & craddock, 1976a) appears to be erroneously old, perhaps because of unrecognized xenolithic material in the analyzed sample. on the basis of the unmodified form of the higher parts of the island, rowley (1989) concluded that at least parts of the volcano were relatively young, probably holocene. holtedahl (1935) interpreted incisions at higher levels as raised shorelines. such uplift could be the result of isostatic adjustment after partial deglaciation and thus be a relatively young feature. this uplift could also be a reflection of hot lithosphere in the area, indicating that magmatic activity is still taking place. in areas where the magmatic activity acknowledgements. we thank the norwegian polar research institute and the scientific crew on the aurora expedition for collecting the samples on peter i 0 y . we thank r. keller for sample preparation and k-analyses in support of the age determinations. a grant from roald amundsens minnefond is gratefully acknowledged. comments by two anonymous reviewers improved the manuscript. this paper is publication no. 103 of the norwegian antarctic research expeditions (1987). references barker, p. f. 1982: the cenozoic subduction history of the pacific margin of the antarctic peninsula: ridge crest-trench interactions. j . geol. soc. london 139, 787-801. bastien, t . w. & craddock. c . 1976a: the geology of peter i island. lnitial reports of the deep sea drilling project x x x v . 341-357. bastien, t. w. & craddock. c. 1976b: igneous rocks of peter i island. antarctic journal 11, 267-269. broch, 0. a . 1927: gesteine von der peter i.-lnsel, west antarktis. auh. norske vid. a k a d . , mat. naturo. ki. no. 9 , cande. s . c . . herron, e. m. & hall, b. r . 1982: the early cenozoic tectonic history of the southeast pacific. earth planet. sci. letters 57, 6 s 7 4 . cassignol, c . & gillot, p.-y. 1982: range and effectiveness of unspiked potassium-argon dating: experimental groundwork and applications. pp. 159-179 in odin. g . s. (ed.): numerical dating and strafigraphy. john wiley & sons, new york. clague, d. a . & dalrymple, g . b. 1987: the hawaiian emperor volcanic chain. part i geologic evolution. pp. s 5 4 in decker, r. w., wright, t. & stauffer, p. h . (eds.): volcanism in hawaii vol. 1. usgs prof, paper 1350. craddock, c. & hubbard, h. a . 1961: preliminary report on the 1960 u.s. expedition to the bellinghausen sea. antarc tica. science 133, 886-887. falloon, t . j . & green, d. h . 1988: anhydrous partial melting of peridotite from 8 to 35 kb and the petrogenesis of morb. j . petrol., special lithosphere issue, 37%414. gillot. p.-y. & nativel. p. 1989: eruptive history of the piton de la fournaise volcano, reunion island, indian ocean. j . volcanol. geotherm. res. 36, 53-66. herron, e . & tucholke, b. e. 1976. sea-floor magnetic patterns and basement structure in the southeastern pacific. initial reports of the deep sea drilling project x x x v , 263-278. holtedahl, 0. 1935: on the geology and physiography of some antarctic and sub-antarctic islands. scient@c results of the norwegian anrarcric expeditions 1929, no. 3 , 83-88. johnson, g . l. 1966: peter i island. norsk polarimt. arbok 1965. 85-93. kimura, k. 1982: geological and geophysical survey in the bellinghausen basin, off antarctica. antarctic record no. 75, 12-24. national institute of polar research, tokyo. lemasurier, w . e . & rex, d. c. 1982: volcanic record of cenozoic glacial history in mane byrd land and western ellsworth land: revised chronology and evaluation of tec tonic factors. pp. 725-734 in craddock, c. (ed.): anrarctic geoscience. the university of wisconsin press, madison. levi, s . , audunsson, h . , duncan, r . a , , kristjansson, l.. 1-41. 98 t . prestvik & r . a. duncan gillot., p.-y. & jakobsson. s. k . 1990: late pleistocene geomagnetic excursion in icelandic lavas: confirmation of the laschamp excursion. earfh planet. sci. letfers 96. 443 457. norsk polarinstitutt 1988: peter i . 0 y . topographic map. scale 1:50.000. oslo. prestvik. t.. barnes. c. g.. sundvoll. b . & duncan. r . a . 1990: petrology of peter i 0 y (peter i island), west antarc tica. 1. vokanol. geothermal re5. 4 4 . 315-338. rowley. p. d. 1989: f . l l . peter i island. pp. 6 s 6 7 in lema surier. w. e . and thomson. j . (eds.): volrunoes of the antarcfir plate. american geophysical union. smellie. j . l.. pankhurst. r . j . . hole. m . j . 8. thomson. j . w. 1988: age. distribution and eruptive conditions of late cenozoic alkaline volcanism in the antarctic peninsula and eastern ellsworth, land. brir. antarctic suru. bull. 80, 21 49. stock, j . & molnar. p. 1987: revised history of early tertiary plate motion in the south-west pacific. nofirre 325, 495-499. tucholke, b. e. & houtz. r . e. 1976: sedimentary framework of the bellinghausen basin from seismic profiler data. initial reporfs of fhe deep sea drilling project x x x v . 197-227. weissel. j . k.. hayes, d . e. & herron, e. 1977: plate tectonic synthesis: the displacements between australia, new zea land and antarctica since the late cretaceous. mar. geol. 25. 231-277. lake sediments and glacial history in the high arctic; evidence from east-central ellesmere island, arctic canada, and from inglefield land, greenland1 weston blake j r blake, weston, jr. 1987: lake sediments and glacial history in the high arctic; evidence from east-central ellesmere island, arctic canada, and from inglefield land, greenland. polar research 5 n . s . , 341-343. weston blake jr., geological survey of canada, 601 booth s t . . ottawa, ontario, k i a oes. canada. deciphering glacial history in many high arctic localities is difficult because: 1) surficial deposits are often thin or non existent, 2) vast tracts are underlain by soft and friable bedrock, 3) the churning effects of frost action and slope processes tend to eradicate traces of glaciation, 4) cold based ice caps leave little trace of their former presence, except where marginal drainage channels form on uphill slopes, and 5) significant areas still are covered by glacier ice. where present, striae show that an area has been glaciated, hut until a technique is devised to determine when a given set of striae was inscribed, or when a striated surface became exposed to daylight (e.g. phillips et al. 1986: elmore & phillips 1987), the timing of the glacial event responsible remains an enigma. one way of approaching the problem of dating glacial events, in the high arctic as elsewhere, is to determine the age of organic deposits associated with till or outwash. radiocarbon dating of the basal increment from a lake sediment core or a peat deposit provides a minimum age for deglaciation and for the onset of organic accumulation. in this connection the advent of "c dating by means of accelerator mass spectrometry (ams) has provided an extremely powerful tool for determining the timing of events more precisely. for instance, the change from marine to lacustrine conditions or, in the case of a lake above the limit of holocene marine submergence, the onset of lacus trine moss growth can be pin-pointed much more accurately using this technique (blake 1985). available basal dates on reliable organic materials from lakes in east-central ellesmere island, an area underlain by granites. migmatites. and associated rocks of the canadian shield, do not exceed 9500 radiocarbon years. the oldest age determinations, among seven lakes dated, have been obtained along the outer east coast, facing smith sound and kane basin: 9370 2 110 years (to-111) from proteus lake at 390 m on pim island (site 1 on fig. 1: 78"41.7'n, 74"23'w) and 9130 f 160 years (gsc 3432) from 'cliff edge pond' at 375 m on bache peninsula (site 2: 79"02'n, 75"04'w; blake 1987). however, the basal organic sediment in 'rock basin lake', at 295m south of ekblaw glacier in innermost baird inlet (site 3: 78o29.5". 76"46.8'w) and 50km southwest of proteus lake, is nearly as old, 8970 c_ 160 years (gsc-3051; blake 1981; smol 1983; hyva rinen 1985). other lakes at even higher clevations and farther inland have yielded younger dates. the basal organic sediment in an i geological survey of canada contribution 24887. con tribution no. 30 from the cape herschel project. unnamed lake at 650 m on knud peninsula (site 4: 79"03'n, 77"27'w), above the junction of beitstad and joke1 fiords, is 6210 2 70 years old (gsc-3602). and algae at a depth of over 4 m in the ice of a lake frozen to the bottom (total ice thickness, 5.45 m) on top of rundfjeld (close to 830 m a.s.1.: site 5: 78"29'n, 8lo21.5'w) yielded an age of 5730 ? 70 years (to 530). the latter site is on a mountain top above the western edge of the central ellesmere island ice cap. on the greenland side of smith sound (a mere 40km wide in places), although several lakes have been cored, ijc dates are available for only 'kap inglefield sb' (site 6: 250m a.s.1.: 78o31.8". 72"21'w). a lake which, like its counterparts on ellesmere island. is well above the limit of holocene marine submergence. the basal organic sediment is 7210 ? 130 years old (gsc-3732: blake et al. 1985; blake 1987). farther south. however, on n o r d v e s t ~ in the carey oer group, northern baffin bay (site 7: 76"43.5'n, 73"ll'w). basal peat on the plateau at 125 m a.s.1.. and above the limit of holocene marine suhmerg ence, is 8940 2 90 years old (gsc-2440; brassard & blake 1978: blake 1987). still farther southeast, on the peninsula of tugtuligssuaq in melville bugt, the basal organic sedimcnt in langeso (site 8: 75"22'n. 58"36'w) is 8540 2 120 years old (k-3276). this lake. at only 15 m a s . ] . , is nevertheless above the local limit of holocene marine submergence (fredskild 1y85a. 1985b). thus, no organic lake sediments have been obtained as yet. in either east-central ellesmere island or northwestern greenland. which span more than holocene time. a particular effort has been made to penetrate as deeply as possible during the coring process, utilizing specially designed equipment. this has been done in order to see if additional organic materials were present beneath thc inorganic horizon (sand, silt, clay. till. or till-like material) in which refusal normally occurs. using the new equipment (a stainless steel barrel with tungsten carbide teeth fitted outside the normal plastic coring tube), which allowed us to rotate the whole coring device after the hydraulic system failed to drive the tube deeper into the sediments, we recovered 8 cm of frozen sediment at the base of a 90 cm-long core in the lake at 650111 on knud peninsula (site 4: 7 . 4 m from ice surface to sediment/water interface). in the case of 'cliff edge pond' on bache peninsula (site 2) we recovered cobbles up to 7 c m in diameter. in neither of these lakes, nor in any others we have cored so far. have buried organic layers been encountered. if any of these sites were free of glacier ice throughout lake wisconsinan time, then longer records of continuous organic 342 weston blake j r . f i g . i. location map for sites discussed in the text lake sediments and glacial history in the high arctic 343 sedimentation should be present, such as those which have been obtained from the yukon territory (rampton 1971; cwynar & ritchie 1980) or from a n d ~ y a , northern norway (vorren 1978). the fact that older organic deposits have not been found suggests that a cover of glacier ice was present until immediate pre-holocene time. the disappearance of a massive volume of ice at this time is in agreement with the drastic warming documented by the changes in 1so/'60 ratios from camp century, greenland (dansgaard et al. 1984) 350 km to the east southeast, from the devon island ice cap (koerner & fisher 1985) 400 km to the south-southwest, and from the agassiz ice cap (koerner et al. 1987) some 250 km t o the north on elles mere island (fig. 1). presumably a similar pattern of ice cap (ice sheet) growth and demise has occurred during each glacial/interglacial cycle. it is also worth noting that shallow lake basins at high elevations, once excavated. may serve as nuclei for the development of small ice caps during succeeding glaciations. as the climate worsens, the thickness of ice on a lake will increase until the lake freezes to the bottom. the level of the ice surface will continue to build up as most of each winter's accumulation of snow remains intact, a moat no longer develops around the lake during the summers. and permanent snowdrifts develop on the periphery of the lake. the result is that the former lake basin becomes the thickest part of a miniature ice cap and, as the snow and ice masses in adjacent lake basins coalesce, a larger ice cap develops. references blake, w., jr. 1981: lake sediment coring along smith sound, ellesmere island and greenland. geol. suru. can., paper blake, w., jr. 1985: radiocarbon dating with accelerator mass spectrometry: results from ellesmere island, district of franklin. geol. suro. can., paper 85-18,4234429. blake, w., jr. 1987: geological survey of canada radiocarbon dates xxvi. geol. suru. can., paper 86-7. 60 pp. blake, w. j r . , boucherle, m . m., smol, j. p., fredskild, b. & janssens, j . a. 1985: holocene lake sediments from inglefield land. northwestern greenland. 4th intern. sym. on paleo limnology (ossiach, austria, sept. 1985). abstracfs, 11. 81-1a, 191-200. brassard, g . r. & blake, w., jr. 1978: a n extensive subfossil deposit of the arctic moss aplodon wormkioldii. can. j . bot. 56, 1852-1859. cwynar, l. c. & ritchie, i. c. 1980: arctic steppe-tundra: a yukon perspective. science 208, 1375-1377. dansgaard, w . , johnsen, s . j., clausen, h . b., dahl-jensen, d . , gundestrup, n . , hammer, c . u . & oeschger, h. 1984: pp. 288-298 in climate processes and climate sensitivity. a m . geophysical union geophysical monogroph 29, maurice ewing vol. 5. elmore, d. & phillips, f. m. 1987: accelerator mass spectro metry for measurement of long-lived radioisotopes. science 236, 54>550. fredskild, b. 1985a: the holocene development of tug tuligssuaq and qeqertat, northwest greenland. meddr. gr@nland, geosci. 14. 20 pp, fredskild, b. 1985b: holocene pollen records from west greenland. pp. 643-681 in andrews, j. t. (ed.): quaternary environments, eastern canadian arctic, baffn bay and west ern greenland. allen & unwin, boston. hyvarinen, h . 1985: holocene pollen stratigraphy of baird inlet, east-central ellesmere island, arctic canada. boreas 14, 1p-32. koerner, r. m. & fisher, d . a . 1985: the devon island ice core and the glacial record. pp. 309-327 in andrews, j. t. (ed.): quaternary environments, eastern canadian arctic. baffn bay and western greenland. allen & unwin, boston. koerner, r. m., fisher, d. a. & paterson, w. s . b. 1987: wisconsinan and pre-wisconsinan ice thicknesses on elles mere island, canada: inferences from ice cores. can. j . earth sci. 24, 296301. phillips, f. m., leavy, b. d . , jannik, n . 0.. elmore, d. & kubik, p. w. 1986: the accumulation of cosmogenic chlorine-36 in rocks: a method for surface exposure dating. science 231, 41-43. rampton, v. n. 1971: late quaternary vegetational and cli matic history of the snag-klutlan area, southwestern yukon territory, canada. geol. soc. america bull. 82, 959-978. smol, j. p. 1983: paleophycology of a high arctic lake near cape herschel, ellesmere island. can. j . bot. 61,2195-2204. vorren. k. d. 1978: late and middle weichselian stratigraphy of and0ya, north norway. roreas 7 , 1%38. response of reindeer and caribou to human activities scott a. wolfe, brad griffith & carrie a. gray wolfe petroleum and mineral exploration and extraction, hydroelectric development, atmospheric transport of contaminants, timber harvesting and tourism are increasing worldwide, especially in the arctic. this development may adversely affect populations of reindeerkaribou (rangifer tarandus) which are the basis of subsistence economies for northern indigenous peoples. our purpose is to present a survey of the literature that has investigated the response of reindeer/caribou to human activities. individuals and groups of reindeerlcaribou: i ) move away from point sources of disturbance; 2) increase activity ahd energy expenditure near disturbance; 3) delay crossing or fail to cross linear structures; 4) shift away from areas of extensive and intensive development; and 5 ) are killed by collisions with vehicles and by hunting along roads. cows and calves during the calving season are the most easily disturbed group. bulls in general and all reindeedcaribou during insect harassment are least likely to avoid development areas. estimation of the proportion of a population that is exposed to disturbance and the implications of this exposure to annual energy budgets, survival and productivity of reindeedcaribou has received little attention. future advances in understanding the implications of human disturbance to reindeed caribou will require cumulative effects assessment at annual, population and regional scales. although some level of cumulative effect is likely, clear separation of cumulative effects of development from natural variation in caribou habitat use and demography will be difficult. s. a. wove, b. grifith & carrie a. g. wove, institute of arctic biology, university of alaska fairbanks, irving i bldg., fairbanks, a k 99775-7000, usa; b. grifith also at usgs, alaska cooperative fish and wildlife research unit, university of alaska fairbanks. caribou and reindeer are the most important subsistence and cultural resources for indigenous arctic dwelling peoples (burch 1972; klein 1989) and are the subject of intense interest by people who view the arctic as one of the last remaining wilderness regions. the welfare of arctic reindeer/ caribou populations is a function of husbandry practices, climatic effects on habitats and anthro pogenic forces within herd ranges (kofinas et al. 2000). advances in operation technology and discoveries of substantial reserves of petroleum and minerals in the arctic have facilitated industrial development in the circumpolar region in the latter half of the 20th century (klein 1980). because many arctic reindeerlcaribou populations have had limited exposure to modern industrial development, there are potential implications of this development for reindeedcaribou movements, distribution and populations. sustainable development requires an under standing of the effects of development on wildlife populations and habitats. during the past 30 years many studies have investigated reindeerlcaribou responses to human activities. this work has been periodically reviewed and synthesized (klein 1971, 1980; shideler 1986; shideler et al. 1986; cronin, ballard, truett e t al. 1994; cronin, ballard, bryan et al. 1998) but not all of these reviews are readily available. our purpose in this paper is to survey the existing literature on the response of reindeerlcaribou to human activities. w e emphasize refereed research and synthesis publications. as much as possible, we restrict our presentation to reported results and avoid reiterat wolfe et al. 2000: polar research 19(1), 63-13 63 ing interpretations of authors. anecdotal observa tions and opinions are generally not reported. internal reports often precede final publications; we concentrate on the latter. the primary human activities that may affect reindeerhribou include: 1) transportation corri dors and associated traffic; 2) activities and infrastructures associated with petroleum, mineral, hydroelectric, forestry and recreational develop ment; and 3) atmospheric transport of contami nants. contaminant, hydroelectric development and surface alteration effects of human activities on reindeerlcaribou are discussed elsewhere in this volume (klein 2000). we focus on the remaining types of human activities and present results of our survey by type of disturbance, tabulate suggested mitigation measures and discuss the direction of future work. transportation aircraft caribou response (walking or running away) to aircraft (overflights, nearby landings) is variable depending on the season, degree of habituation, type of aircraft, altitude, airspeed, weather condi tions, frequency of overflights, and the sex and age composition of caribou groups. caribou reacted to small fixed-wing and helicopter overflights most strongly during calving (late may to early june), post-calving (early june to late june) and winter (calef et al. 1976). calves were most reactive, but cows did not abandon their calves even when aircraft passed directly overhead or landed nearby. habituated caribou may be less reactive to aircraft. caribou of the habituated delta herd, alaska, ran from 36% of small single-engine aircraft over passes in winter while non-habituated caribou of the western arctic herd, alaska, ran from 82% of small aircraft overpasses in winter (davis et al. 1985; valkenburg & davis 1985). caribou were more responsive to helicopter than to small fixed wing overflights only at low ( < l o o m above ground level [a.g.l.]) altitudes (mccourt et al. 1974), and response to both types of aircraft dissipated up through flight altitudes of 300 400 m a.g.1. (mccourt et al. 1974; gunn & miller 1978) during calving and post-calving. cows with calves and larger groups of caribou were more likely to respond to helicopter overflights than were other sex and age classes or smaller groups (gunn & miller 1978; miller & gunn 1980). however, there was no statistical difference in pre and post-disturbance activity even though caribou tended to walk away from helicopter landing sites (gunn et al. 1985). repeated exposure to low-level military jet overflights, especially during sensitive periods, may reduce calf survival and increase daily activity. the frequency of exposure of cows to low-level jet overflights during calving, immediate post-calving and summer (early july to mid september) explained 32%, 53% and 48% of the variance in calf survival, respectively (narrington & veitch 1992). however, calf survival was not related to jet aircraft exposure during pre-calving, late-post calving and fall. during post-calving and insect harassment, caribou of the delta herd, alaska, increased daily activity and reduced resting time when overflown by military jet aircraft at approximately 33 m a.g.1. (maier 1996; maier et al. 1998). however, neither harrington & veitch (1992) nor maier et al. (1998) found an increase in activity or distance travelled by caribou exposed to experimental jet overflights as low as 30 m a.g.1. during late winter. an energetics model predicted that the weight of autumn body fat would decline by 0.07-0.41 kg in a year with favourable environmental conditions and would decline by 0.07-0.64 kg in a year with harsh environmental conditions if caribou were exposed to 10-40 consecutive days of single disturbance events by low-altitude jet overflights during post-calving (luick et al. 1996). the highest frequency of exposure might reduce the probability of pregnancy the following year by 4 5% under normal or poor environmental condi tions, and severe insect harassment might exacer bate this effect. however, because only a small proportion of the population was likely to be exposed, jet aircraft exposure was unlikely to cause a substantial reduction in pregnancy rates (luick et al. 1996). roads, railways and infrastructures effects of transportation corridors on reindeer/ caribou may be influenced by adjacent infrastruc tures, vehicle type, frequency of traffic, purpose of road use, habitat surrounding the roads, visual attributes of roads, habituation, sex and age of reindeerkaribou and season of use. transportation comdors that provide access to, but are not part of, 64 response of reindeer and caribou to human activities a primary development zone (e.g. dalton highway in alaska, dempster highway in canada) can contribute to effects of development on caribou. the appearance of roads may influence caribou reaction. elevated roads that present a visual barrier, roads that create a break in habitat in forested areas, or roads with adjacent snow berms or habitat that obscured vision were most strongly avoided by caribou in fall and winter (surrendi & debock 1976). on calving grounds, caribou were deflected by pipeline berms greater than 1.5 m above ground level because berms presumably served as visual barriers (hanson 1981). heavy traffic may accentuate the reaction of reindeerkaribou to roads and railways, impede crossings and serve as barriers, result in substantial mortality from collisions and hunters, and increase vigilance behaviour that may reduce foraging efficiency (skoog 1968; klein 1971; villma 1975; surrendi & debock 1976; roby 1978; koskela & nieminen 1983; skrobov 1984). substantial mortality and disruption of reindeer movements by railways in the arkangelsk and taimyr development regions of russia was summarized by klein (1971). very high rates of traffic ( 2 1 vehiclehin) probably create a barrier to caribou movements (murphy 1988), but caribou may avoid heavy traffic and hunters by crossing roads at night (skoog 1968; surrendi & debock 1976). harassment by insects, especially oestrid flies (warble flies and nose bot flies), increases the propensity of all sex and age classes to cross roads and infrastructures (child 1973; smith & cameron 1983; murphy & curatolo 1987; murphy 1988; pollard et al. 1996; noel et al. 1998). in contrast, infrequently travelled transportation corridors resulted in low numbers of road-kills, did not deter road crossing by caribou, and had no observable effect on traditional migration routes, annual distribution or energetic costs (klein 1971; johnson & todd 1977; johnson 1985; russell & martell 1985). traditional migrations have con tinued across constructed railways or roads in newfoundland (bergerud 1971), yukon (surrendi & debock 1976; russell & martell 1985), british columbia (johnson & todd 1977) and alaska (skoog 1968), but have ceased after construction of a railway and highway between summer and winter ranges in norway (nellemann et al. 2000). cows with calves in spring and summer were more reactive to infrastructures than bulls (roby 1978; cameron 1983; smith & cameron 1983; whitten & cameron 1983; dau & cameron 1986; klein 1991; cameron, reed et al. 1992; cronin. ballard, truett et al. 1994; nellemann & cameron 1996, 1998). cow caribou distribution shifted away from pipelines, roads and associated traffic during calving (cameron & whitten 1979; dau & cameron 1986; lawhead 1988; cameron, reed et al. 1992) even though vehicular traffic on the study area road was limited (100-200 vehicles/day) (cameron, reed et al. 1992). mean densities of calving caribou were 2-18 times higher outside the primary development area of the prudhoe bay oil field, alaska (whitten & cameron 1985). few caribou were present in a zone within 3-5 km of roads during calving, and niovements were deflected or delayed near human activity (law head 1988). with construction of an oil field access road through a calving concentration area, mean caribou density decreased 78% within 1 km of roads and concurrently increased 321% in areas 5-6km from roads (cameron, reed et al. 1992). thus, the footprint of infrastructure, in terms of avoidance by calving cows, extended 5-6 km outward from the actual infrastructure (cameron, reed et al. 1992). further, caribou density at calving was inversely related to road density, declining by 63% from baseline densities when there was >0.3km road/km2 and declining by 86% from baseline densities when there was >0.9 km road/km2 (nellemann & cameron 1998). avoidance of roads was accentuated in otherwise preferred foraging terrain (nellemann & cameron 1996). in spring and fall, designated game crossings, sag bends and buried pipeline sections were used by 29% of caribou crossing the trans-alaska pipeline system (taps) but other structures were used little because they were outside major caribou crossing zones (carruthers & jakimchuk 1987). caribou crossed under pipes with heights ranging 1-5.3m (carruthers & jakimchuk 1987) but preferred buried sections of pipeline and pipes elevated > 2.4 m compared to those elevated <2.1 m for winter crossing of taps (eide et al. 1986). during migration, caribou followed cleared seismic lines in taiga when these clearings were parallel to migration routes. however, when the clearings were perpendicular to migration routes, caribou were usually deflected or delayed (ban field 1974). most (77-85%) caribou avoided expenmental pipeline structures on the calving ground in summer (child 1973). ramps were used most frequently (17.6%), and 76% of caribou that wolfe et al. 2000: polar research 19(1), 63-73 6 5 crossed successfully used ramps rather than pipe line underpasses. individuals were more likely to cross successfully (62%) than were groups of 2 1500 animals (24%) and only 8% of groups larger than 10 animals crossed successfully. groups led by cows were more likely to cross (38.3%) than were groups led by bulls (8%). crossing success was greatest during periods of insect harassment, and insect harassment was a more important influence on crossing success than season or habituation to experimental crossing structures (child 1973). once oil fields were operational, caribou selected buried sections of pipeline as crossings more often than expected (curatolo & murphy 1986). in contrast to earlier experimental work (child 1973), curatolo & murphy found no difference between cow-calf and bull groups in the percentage of successful pipeline crossings by central arctic caribou. child’s work was con ducted early in the industrial development of prudhoe bay when caribou had little or no experience with infrastructures, while curatolo & murphy’s work was conducted after caribou had been exposed to industrial development for at least a decade. in agreement with child’s experimental work, curatolo & murphy found that large groups of caribou tended to cross pipelines less success fully than small groups. group size, insect harassment and the combina tion of roads and traffic levels paralleling pipelines may interact to affect pipeline-crossing success by caribou. crossing frequency was lowest where the road was adjacent to a pipeline and traffic was highest (15 vehicleshour) (curatolo 1983; curat 010 & murphy 1986). elevated pipelines that closely paralleled roads with high traffic levels reduced crossing success and increased movement rates (murphy 1988) by caribou. insect harassment may have caused caribou to form larger groups (murphy 1988; pollard et al. 1996; noel et al. 1998), these groups may have contained easily disturbed individuals, and these reactive indivi duals may have reduced crossing success of the larger groups (smith & cameron 1983; curatolo & murphy 1986). probably because larger groups of caribou rook longer to cross pipefines and roads and the likelihood of vehicular traffic increased with time, crossing success was significantly reduced by 55% when roads paralleled elevated pipelines and there was no insect harassment or there was mosquito harassment only (curatolo & murphy 1986). however, when caribou were harassed by oestrid flies, roadpipe combinations did not reduce crossing success (smith & cameron 1983; murphy 1988). both insect harassment and elevated pipelines that paralleled roads with traffic reduced the time that caribou spent lying and increased the time spent moving (fancy 1983; murphy & curatolo 1987). insect harassment, but not oil field disturbance, reduced the time caribou spent feeding (murphy & curatolo 1987). during insect harassment, caribou used oil field gravel pads and shade provided by elevated production facilities, regardless of sex and age composition of the group (truett et al. 1994; pollard et al. 1996; noel et al. 1998). wind speeds were higher on gravel pads, and mosquitoes were more abundant on tundra than on active or inactive gravel pads (pollard et al. 1996). when disturbed by humans or vehicles, caribou using gravel pads during insect harassment usually responded by shifting position on the pads (noel et al. 1998). caribou traversed oil fields during insect harassment and this activity was highly variable and changed within hours (pollard et al. 1996). more caribou were observed within the prudhoe bay oil field when insect activity was moderate to high than when insect activity was low (pollard et al. 1996). cronin, amstrup et al. (1998) found no relationship between caribou distribution and distance from oil field infrastructure during the entire post-calving period for the central arctic herd. however, cameron, lenart et al. (1995) noted decreased east-west movements of radio collared caribou through the most intensively developed portion of the prudhoe bay oil field during insect harassment. recreational activities exposure to recreational activities may result in increased vigilance, avoidance behaviour and redistribution of caribou. tyler (1991) found that reindeer that were experimentally approached by snowmobiles in scandinavia first reacted at a distance of 640 m, were disturbed at a distance of 410 m, fled at a distance of 80 m, and travelled 160m in 22 seconds after disturbance in winter. individual disturbance events had negligible effects on the daily energy budgets of reindeer (tyler 199 1 ) . severe or prolonged disturbance (herding) of reindeer by snowmobiles could lead to exhaustion (muller-wille 1975) or cause panic 66 response of reindeer and caribou to human activities among animals (klein 1971). caribou may avoid areas where hunters pursue them on snowmobiles (smith 1988). in denali national park, alaska, the frequency of strong reactions by caribou to tourist buses increased as the disturbance escalated from a drive by, to a stop with quiet bus occupants, to a stop with noisy bus passengers or passengers departing from the bus (tracy 1977). the number of severe reactions nearly doubled when people unloaded from buses in denali national park (dean & tracy 1979). caribou in denali reacted less severely to tour bus traffic with increasing distance from roads; 60% and 10% of caribou reacted visually to traffic 5 1 0 0 m and >400 m, respectively (dean & tracy 1979). reindeer avoided an area within 5 km of a tourist resort in norway in march (nellemann et al. zooo)-and similar avoidance has been observed during winter (helle & sarkela 1993) and spring (vistness 1999). forestry timber harvest and post-harvest management may directly and indirectly affect winter habitats of arctic calving reindeerkaribou. selective harvest of merchantable trees and snags removed 30-55% of available lichens (armleder & stevenson 1996). although live biomass of arboreal lichen on remaining trees increased in partial-cut forests (rominger et al. 1994), the total number of trees per hectare and overall availability of lichen biomass decreased. after clear-cutting, natural lichen regeneration only occurred within 350 m of mature forest with high lichen abundance (stevenson 1990). post-harvest burning denuded lichen cover for long periods, even though growth of higher plants may have increased (eriksson 1975). after clear-cutting, caribou moved away from clear-cut areas, selected mature black-spruce forest, and avoided burned areas and hardwood forests (chubbs et al. 1993). conflicts between forestry and caribou habitat will likely be most pronounced in lichen-moss habitat types where caribou winter range and high quality timber production overlap (cichowski 1996). recently harvested forests are often fertilized to enhance regeneration. in winter, cratering through snow for forage by reindeer in sweden was reduced by 5 0 4 5 % for one year in 50 x 50 m plots fertilized with ammonium nitrate compared to unfertilized plots; moreover, cratering was reduced by 90-95% for two years in plots fertilized with urea (eriksson 1980). domestic reindeer refused to eat wood fertilizers with no other food supplement, preferred to eat pure lichen over lichen containing fertilizers, and ate signifi cant amounts of fertilized lichen only when no other forage was available (rajala & westerling 1980). artificial dosages of 1 .0 g -n03/kg body weight and 0.4 g -n03/kg body weight were lethal and chronically toxic, respectively, when adminis tered through stomach tubes in 5 or 10% aqueous solution. however, reindeer in good condition were more resistant to dosages of -no3 than reindeer in poor condition. although fertilizers may reduce feeding by reindeer, they are unlikely to reach lethal or toxic levels when correctly applied (nordkvist & erne 1983). mitigation measures mitigation measures emphasize conducting re search and planning before development, mini mizing disturbance of reindeerkaribou during critical stages of their life history, providing free access to important habitats, preserving the value of important habitats and minimizing direct mortalities (table 1). although these mitigation measures have been good faith attempts to minimize caribou disturbance and redistribution, the population level effectiveness of mitigation has not been adequately assessed. discussion it is clear that reindeerkaribou may respond negatively to human activity, vehicles and aircraft, roads and railways, and industrial development infrastructures. in addition, timber harvesting, linear transportation, and infrastructure corridors may fragment or degrade habitats. overt beha vioural responses can result in elevated energy requirements for individuals and redistribution of animals. cows during calving, and larger ( > 10) groups, are most susceptible to these effects. the behavioural effect is positively related to the novelty, intensity and spatial extent of the disturbance, but may be reduced or eliminated during periods of environmental stress such as harassment by insects. wolfe et al. 2000: polar research 19(1), 63-73 67 table i , mitigation measures for human disturbance of reindeedcaribou. mitigation measure reference 0 0 0 a a 0 a 0 a 0 a 0 0 a involve biologists in project design. minimize traffic and prohibit unnecessary access in and near oil fields, especially i n critical habitats and seasons. avoid construction and exploration during calving and post calving. limit surface development and minimize the “network” effect of road development. make road berms < 1.2 m above ground level, elevate pipes 2 1 .5 m a.g.1. from the bottom, bury pipes where feasible. maintain passage sites for pipeline or other infrastructures at known caribou crossing areas. separate elevated pipelines from roads, especially heavily travelled roads, by e 150 m. use monitoring personnel to minimize exposure of caribou. revegetate scarred lands. avoid multiple passes of tracked vehicles in sensitive vegetation types. restrict hunting from service roads in and near industrial complexes. avoid low-level aircraft overflights of concentration areas, especially during calving and post-calving. restrict overflight altitudes to > 150 m a.g.1. in spring and fall and to >300 m a.g.1. during calving. create development-free sanctuaries and special harvest management strategies in areas where developments were poorly designed. 0 klein 1 9 8 0 cronin, ballard, truett et al. 1994. 0 murphy 1988; cronin, ballard, truett et al. 1994; a jingfors et al. 1983: cronin, ballard, truett et al. 0 smith et al. 1994; nellemann & cameron 1998. cameron, lenart et al. 1995. 1994. 0 hanson 1981; lawhead 1988; curatolo & murphy child 1973: eide 1986; skrobov 1984; curatolo & 0 curatolo & murphy 1986; murphy & curatolo 1986; eide 1986 murphy & curatolo 1987. murphy 1986; murphy & curatolo 1987. 1987; murphy 1988; cronin, ballard, truett et al. 1994. a crouin, ballard, truett et al. 1994. 0 jorgenson & joyce 1994. 0 raynolds & felix 1989. 0 cronin, ballard, truett et al. 1994. 0 calef et al. 1976; harrington 1991; harrington & 0 calef et al. 1976; mccourt et al. 1974; calef et al. veitch 1992; maier et al. 1998. 1976; gunn & miller 1978; cronin, ballard, truett et al. 1994. syroechkovskii 1990; shtil’mark 1984; shtil’mark & azarov 1984. 0 syroechkovskii 1984; sokol’skii 1984; the population level effects of disturbance on reindeer/caribou are less clear. reduced density of reindeedcaribou near disturbance suggests that individual avoidance of disturbance accumulates at the population level. however, the quantitative implications of redistribution in terms of access to forage, exposure to other threats (e.g. predation, hunting), or population performance have not been adequately addressed. although animals may move to less desirable habitat, studies necessary to demonstrate that displacement habitat does not meet requirements have not been conducted. the current discussion largely assumes that a negative behavioural response by individuals implies a negative numerical response by the population. whether a numerical response follows a beha vioural response will depend on the quantity, quality and accessibility of alternate habitats in relation to animal requirements. estimation of the net effect of disturbance on caribou will require quantitative assessment of the cumulative effects of disturbance. cumulative effects are the changes in population performance (e.g. demography, size and distribution) that accrue as the sum or product of individual disturbance events (spaling & smit 1993, 1995). cumulative costs will be a function of the intensity and frequency of disturbance events, the propor tion of the population that is exposed to dis turbance, the location and temporal persistence of disturbance and the suite of disturbances that impinge on individuals across seasonal ranges. ideally, clear cause-effect relationships between disturbance and reindeerkaribou performance should be established (boyle et al. 1997) but the nature of industrial development and wide-ranging behaviour of reindeedcaribou precludes rigorous field experimentation. reliance on robust correla tions and off site experimental testing of key cause-effect mechanisms will be required. disturbance effects may accumulate both spa tially and temporally (spaling & smit 1995), and result from additive individual events of the same nature, or from interactive and multiple events of different natures (spaling & smit 1993). thus, disturbance events that are individually inconse 68 response of reindeer and caribou to human activities quential to population performance may accumu late across animals, space and time in a simple or complex manner and be expressed at the popula tion level. expression of cumulative effects may not coincide in space or time with a particular disturbance. for example, small changes in proportional intake of forages of varying digest ibility during calving and post-calving may have major effects on net diet quality (white 1983) and influence summer weight gain. reduced weight gain on summer ranges may be expressed as reduced parturition rates in the following spring (cameron & ver hoef 1994) o r as elevated mortality rates in winter (white 1992). cumulative effects must be of consistent direction and exceed natural variability within or among herds to be detectable. for example, a 3 5 % cumulative reduction in parturition or calf survival would be difficult to demonstrate in a system where parturition or calf survival normally varied by 15% among years (walsh et al. 1995). small individual or cumulative effects on energy expenditure, parturition or survival that may have biological significance to population trajectory are unlikely to be statistically detectable unless a substantial proportion of the population is mon itored (walsh et al. 1995). caribou inhabit highly variable environments and their populations fluc tuate dramatically at decadal scales for reasons that are not well understood. thus, assessment of cumulative effects solely on the basis of popula tion level is ill-advised without an understanding of the mechanisms that drive population perfor mance. confounding variables may either mask or enhance the appearance of cumulative disturbance effects. natural system variability may influence not only the detectability but also the level of effect of disturbance on reindeedcaribou. the primary effect of disturbance may be to increase variability in distribution and population performance rather than to alter mean values. variance is the most important determinant of population persistence (leigh 1981) and natural and anthropogenic variance will have both temporal and spatial components. annual or seasonal variance in environmental conditions may affect the local expression of disturbance on reindeerkaribou. many studies of the effects of human activity on caribou have been conducted during the recent period of global warming. during this warming, the trend in s p r i n g h m m e r environmental conditions (myneni et al. 1998) has been quite variable among arctic reindeedcaribou ranges. this has two potential implications. first, any individual or population level costs of disturbance are proportionally less important when local environmental conditions are favourable. if requirements are exceeded, an energetic or performance cost may be accommo dated. conversely, favourable environmental con ditions may accentuate behavioural avoidance of disturbance by reindeedcaribou if the availability of adequate alternate habitats is enhanced. under less favourable environmental conditions, suitable alternate habitats may not be available and avoidance of disturbance may be less likely. from a seasonal perspective, caribou use of the prudhoe bay oil field during periods of insect harassment (pollard et al. 1996) is an example of this latter phenomenon. spatial variance in environmental conditions may affect the expression and detectability of disturbance on reindeerkaribou as well. all herds should not b e expected to show similar sensitivity. herds that occupy low quality or more variable ranges, or those that are exposed to multiple types of disturbance in several portions of their annual ranges, may be less resilient to disturbance. for example, the population size of the porcupine caribou herd, which calves in north-eastern alaska, has never increased at more than an approximate 5% annual rate (walsh et al. 1995) and since 1989 has declined by approximately 5 % annually. during the same period the population sizes of the other three arctic calving herds in alaska (central arctic, teshekpuk lake, western arctic) have grown at rates approximating 10%. a similar population cost of disturbance (e.g. 2% reduction in growth rate) would be expected to have a proportionately greater effect on the porcupine herd than on any of the other three alaskan herds. unfortunately, quantitative estimates of the exposure rate of individuals o r of the proportions of populations that are exposed to human activities are lacking. thus, modelled estimates of energetic costs of hypothetical cumulative exposure at the individual level (luick et al. 1996; bradshaw et al. 1997, 1998) cannot be quantitatively projected to the population. to obtain estimates of cumulative population exposure, substantially more use of satellite and conventional radio-telemetry on an adequate and representative sample of individuals in potentially affected populations will be re quired. estimates of productivity will continue to wolfe et al. 2000: polar research 1 9 ( 1 ) , 63-73 69 require field-based sampling. remote sensing of habitats may provide the opportunity to monitor long-term trends in background habitat conditions and help partition the effects of habitat and disturbance on population performance. a useful interim approach will be to establish habitat-demography relationships in undisturbed systems that have adequate data, and use these relationships as tools to hypothesize the implica tions of disturbance to reindeer/caribou in dis turbed systems. monitoring systems can then be designed to test these hypotheses. currently, little is known of the relative importance of forage availability, human harvest or natural predation on long-term population sizes of arctic caribou herds. in remote arctic systems, often all that is routinely and rigorously monitored is population size. more studies of habitat-demography relationships are needed to elucidate the mechanisms of interaction and to assess the relative value of habitats. substantially more empirical and modelling work needs to be conducted before the effect of human activity on caribou populations can be understood and predicted. studies that identify the mechanisms of cumulative population response, estimate exposure of individuals and populations, and model population response of reindeerlcaribou to human activity are the most neglected and needed future endeavours. in the interim, the management. vol. 2. iucn new ser. 24, 797-804. morges, switzerland. int. union for the conservation of nature. bergerud, a. t. 1971: the population dynamics of newfound land caribou. wildl. monogr. 25, 1-25. boyle, j. r. and 12 others. 1997: cumulative effects of forestry practices: an example framework for evaluation from oregon, u.s.a. biomass and bioenergy 13,223-245. bradshaw, c. j. a., boutin, s. & hebert, d. m. 1997: effects of petroleum exploration on woodland caribou in northeastern alberta. j . wildl. manage. 61, 1127-1 133. bradshaw, c. j . a,, boutin, s. & heben. d. m. 1998: energetic implications of disturbance caused by petroleum exploration to woodland caribou. can. j . zool. 76, 1319-1324. burch, e. s., jr. 1972: the caribou/wild reindeer as a human resource. amer. antiq. 37, 337-368. burkes, f. 1988: the intrinsic difficulty of predicting impacts: lessons from the james bay hydro project. environ. impact assess. rev. 8 , 201-220. calef, g. w., debock, e. a. & lortie, g. m. 1976: the reaction of barren-ground caribou to aircraft. arctic 29, 201-212. cameron, r. d. 1983: issue: caribou and petroleum develop ment in arctic alaska. arctic 36, 227-23 1. cameron, r. d., lenart, e. a,, reed, d. j . , whitten, k . r. & smith, w. t. 1995: abundance and movements of caribou in the oilfield complex near prudoe bay, alaska. rangifer 15, 3-7. cameron, r. d., reed, d. j., dau, j. r. & smith, w. t . 1992: redistribution of calving caribou in response to oil field development on the arctic slope of alaska. arctic 45, 338 342. cameron, r. d. & ver hoef, j. 1994: predicting parturition rate of caribou from autumn body mass. j . wildl. manage. 58, 674-678. cameron, r. d. & whitten, k. r. 1979: seasonal movements and sexual segregation of caribou determined by aerial prudent course of action is to avoid unnecessary survey. j . wild[. manage. 43,626-633, disruption of natural patterns of landscape use by reindeer/caribou, to plan and imp1e ment mitigation procedures in development areas, and to closely monitor the effectiveness of existing mitigation techniques. carruthers, d. e. 8~ jftkimchuk, r. d. 1987: movements of the nelchina caribou herd in relation to the trans-alaska pipeline. wild/. so=. n u ( [ . 15, 414-420, (rang@ tarandus granti) to simulated pipeline and pipeline crossing structures at prudhoe b a y , aluaka. completion reuort to alaska piueline s e n . c o . alaska coooerative child, k. n. 1973: the reactions of barren ground caribou wildlife research unit, univ. of alaska, fairbanks. chubbs, t. e., keith, l. b., mahoney, s. p. & mccrath, m . j . 1993: responses of woodland caribou tarandus caribou) to clear-cutting in east-central newfoundland. can. j . 2001. 71, 4 8 7 4 9 3 . cichowski, d, b, 1996: managing woodland caribou i n west central british columbia. rangifrr, spec. issue 9, 119-126. cronin, m. a,, amstrup, s . c., durner, g. m., noel, l. e., mcdonald, t . l. & ballard, w. b. 1998: caribou distribution acknowledgements. this work was funded by the canadian environment and renewable resources directorate, northern affairs program, department of indian affairs and northern development, and by national science foundation grant opp-9521459. we thank s. a. kalff and d. e. russell for their facilitation of this work. a. g u m , d. r. klein, f. a. servello and r. t . shideler provided constructive comments on early versions of this paper. references armleder, h. m. & stevenson, s. k. 1996: using alternative silvicultural systems to integrate mountain caribou and timber management in british columbia. rangifer, spec. issue 9, banfield, a. w. 1974: the relationship of caribou migration behavior to pipeline construction. in v. geist & f. walther (eds.): the behavior of ungulates and its relation to 141-148. during the post-calving period in relation to infrastructure in the prudhoe bay oil field, alaska. arctic 51, 85-93. cronin, m. a., ballard, w. b.. bryan, j . d., pierson, b. j. & mckendrick, j . d. 1998: northern alaska oil fields and caribou: a commentary. bio/. conserv. 83, 195-208. cronin, m. a,, ballard, w. b., truett, j. & pollard, r. 1994: mitigation of the effects of oil field developmenl and transportation corridors on caribou. r n a / report for the alaska caribou steering committee. lgl alaska research associates, inc. anchorage. curatolo, j. 1983: caribou response to the pipelinehoad complex in the kuparuk oil field, alaska. in a. m . martell ' 70 response of reindeer a n d caribou to h u m a n activities & d. e. russell (eds): caribou and human activity. proceedings of the first north american caribou workshop, whitehorse, y.t., 1983. pp. 62. ottawa: canadian wildlife service. curatolo, j . a. & murphy, s . m. 1986: the effects of pipelines, roads, and traffic on the movements of caribou, raiyifer tarandus. can. field-nal. 100, 21 8-224. dau, j. r. & cameron, r. d. 1986: effects of a road system on caribou distribution during calving. rangifer, spec. issue i , 95-101. davis, j . l., valkenburg, p. & boertje, r. d. 1985: disturbance and the delta caribou herd. in a. m. martell & d. e. russell (eds.): caribou and human activity. proceedings of the first north american caribou workshop, whitehorse, y.t., 1983. pp. 2-6. ottawa: canadian wildlife service. dean, f. c. & tracy, d. m. 1979: mckinley’s shuttle bus syqtem and the management of traffic impact upon wildlife. i n r. ittner et al. (eds.): recreational impact on wildfands conference proceedings. u s forest service no. r-6-001 1979. pp. 263-270. seattle, wa. eide, s. h., miller, s . d. & chihuly, m. a. 19867 oil pipeline crossing sites utilized in winter by moose, alces alces, and caribou, rangifer tarandus, in southcentral alaska. can. field-nat. 100, 197-207. eriksson, 0. 1975: silvicultural practices and reindeer grazing in northern sweden. in luick et al. (eds.): proceedings of the first international reindeercaribou sympo.iium, fairbanks, alaska, 1972. biol. pap. univ. alaska, spec. rep. i , 108-1 12. eriksson, 0. i 9 8 0 effects of forest fertilization on the cratering intensity of reindeer. i n e. reimers et al. (eds.): proceedings of the second international reindeedcaribou sympusium, rgros, norway, 1979. pp. 2 6 4 0 . trondheim: direktorat for vilt og ferskvannsfisk (directorate of game and freshwater fish). fancy, s. g. 1983: movements and activity budgets of caribou near oil drilling sites in the sagavanirktok river floodplain, alaska. arctic 36, 193-197. gum, a. & miller, f. l. 1978: caribou and muskoxen response to helicopter harrassment, prince of’ wales island, 1976-77. escom no. ai-30. canadian wildlife service, fisheries and environment canada. gunn, a., miller, f. l., glaholt, r. & jingfors, k. 1985: behavioral responses of bmen-ground caribou cows and calves to helicopters on the beverly herd calving grounds, northwest territories. in a. m. martell & d. e. russell (eds.): caribou and human activity. proceedings of the first north american caribou workshop, whitehorse, y . t., 1983. pp. 10-14. ottawa: canadian wildlife service. hanson, w. c. 1981: caribou (rungifer tarandus) encounters with pipelines in northern alaska. can. field-nat. 95, 57-62. harrington, f. h. 1991: short-term impacts of low-level jet fighter training on caribou in labrador. arctic 44, 318-327. harrington, f. h. & veitch, a. m. 1992: calving success of woodland caribou exposed to low-level jet fighter overflights. arctic 45, 213-218. helle, t. & sarkela, m. 1993: the effects of outdoor recreation on range use by semi-domesticated reindeer. scand. j . for. res. 8, 123-133. jingfors, k., gum, a. & miller, f. l. 1983: caribou disturbance research on the beverly calving grounds, northwest t e r r tories, canada. acta zool. fenn. 175, 127-128. johnson, d. r. 1985: man-caused deaths of mountain caribou, rangifer tarandus, in southeastern british columbia. can. field-nat. 99, 542-544. johnson, d. r. & todd, m. c. 1977: summer use of a highway crossing by mountain caribou. can. field-nut. 91, 3 12-314. jorgenson, m. t. & joyce, m. r. 1994: 6 strategies for rehabilitating land disturbed by oil development in arctic alaska. arcfic 47, 3 7 4 3 9 0 . klein, d. r. 1971: reaction of reindeer to obstructions and disturbances. science 173, 393-398. klein, d. r. 1980: reaction of caribou and reindeer to obstructions: a reassessment. in e. reimers et al. (eds.): proceedings of the second international reindeerkaribou symposium, rlros, norway, 1979. pp. 519-526. trondheim: direktorat for vilt og ferskvannsfisk (directorate of game and freshwater fish). klein, d. r. 1989: northern subsistence hunting economies. in r. j . hudqon et al. (eds.): wildlife production systems: economic utilisution of wild ungulates. pp. 9& 1 i i . cam bridge: cambridge university press. klein, d. r. 1991: caribou in the changing north. appl. anim. behav. sci. 29, 279-291. klein, d. r. 2000: arctic grazing systems and industrial development: can we minimize conflicts’? polar rgs. 19(1), 91-98. kofinas, g., osherenko, g., klein, d. & forbes, b. 2000: research planning in the face 01 changc: the human role in reindeerkaribou systems. polar res. 19(1), 3-21, koskela, k. & nieminen, m. 1983: death among reindeer caused by traffic in finland during 1 9 7 6 8 0 . acta 2001. fenn. 175, 163. lawhead, b. e. 1988: distribution and movements of central arctic herd caribou during the calving and insect seasons. proceedings of the third north american caribou workshop. wildl. tech. bull. 8, 8-13. alaska dept. of fish and game. leigh, e. g., jr. 1981: the average lifetime of a population in a varying environment. j . theor. biol. 90, 213-239. luick, b. r., kitchens, j. a,, white, r. g. & murphy, s . m. 1996: modeling energy and reproductive costs in caribou exposed to low flying military jet aircraft. rangifer, spec. issue 9, 209-212. maier, j. a. k. 1996: ecological and physiological aspects of caribou acfivity and responses to aircrafi overflights. ph.d. diss., university of alaska fairbanks. maier, j. a. k., murphy, s. m., white, r . g. & smith, m. d. 1998: responses of caribou to overflights by low-altitude jet aircraft. j . wildl. manage. 62, 752-766. mccourt. k. h., feist, j . d., doll, d. & russell, j . j . 1974: disturbance studies of caribou and other mammals in the yukon and alaska, 1972. biol. rep. ser. 5. renewable resources consulting services ltd. miller, f. l. &gum, a. 1980: responses of peary caribou cow calf pairs to helicopter harassment in the canadian high arctic. in e. reimers et al. (eds.): proceedings o f t h e second international reindeerkariboia symposium, rbros, norway, 1979. pp. 497-507. trondheim: direktorat for vilt og ferskvannsfisk (directorate of game and freshwater fish). muller-wille, l. 1975: changes in lappish reindeer herding in northern finland caused by mechanization and motorization. in luick et al. (eds.): proceedings of the firsr international reindeerkaribou symposium, fairbanks, alaska, 1972. biol. pap. univ. alaska, spec. rep. 1, 122-126. murphy, s . m. 1988: caribou behavior and movements in the kuparuk oilfield: implications for energetic and impact analyses. wildl. tech. bull. 8, 19c209. alaska dept. fish & game. w o l f e e t al. 2000: polar r e s e a r c h 19(1), 63-73 71 murphy, s. m. & curatolo, j. a. 1987: activity budgets and movement rates of caribou encountering pipelines, roads, and traffic in northern alaska. can. j. zool. 65, 2483-2490. myneni, r. b., tucker, c. j . , asrar, g. & keeling, c. d. 1998: interannual variations in satellite-based vegetation index data from 1981 to 1991. j. geophys. res. 103, 6145-6160. nellemann, c. & cameron, r. d. 1996: effects of petroleum development on terrain preferences of calving caribou. arctic 49,23-28. nellemann, c. & cameron, r. d. 1998: cumulative impacts of an evolving oil-field complex on the distribution of calving caribou. can. j. zool. 76, 1425-1430. nellemann, c . , jordhoy, p., stoen, 0. & strand, 0. 2000: cumulative impacts of tourist resorts on wild reindeer (rangifer tarandus tarandus) during winter. arctic 53, 9-17. noel, l. e., pollard, r. h., ballard, w. b. & cronin, m . a. 1998: activity and use of active gravel pads and tundra by caribou, rang& tarandus granti, within the prudhoe bay oil field, alaska. can. field-nut. 112, 4 0 0 4 0 9 . nordkvist, m. & erne k. 1983: the toxicity of forest fertilizers (ammonium nitrate) to reindeer. acta zool. fenn. 175, 101 105. pollard, r. h., ballard, w. b., noel, l. e. & cronin, m . a . 1996: parasitic insect abundance and microclimate of gravel pads and tundra within the prudhoe bay oil field, alaska, in relation to use by caribou, rangifer tarandus granti. can. field-nut. i1 0 , 649-658. rajala, p. & westerling, b. 1 9 8 0 responses of corral-fed reindeer to some commonly-used wood fertilizers in finland. in e. reimers et al. (eds.): proceedings of the second international reindeerkarihou symposium, r@ros, norway, 1979. pp. 240-243. trondheim: direktorat for vilt og ferskvannsfisk (directorate of game and freshwater fish). raynolds, m . k . & felix, n. a. 1 9 8 9 airphoto analysis of winter seismic disturbance in northeastern alaska. arctic 4 2 , 362-367. roby, d. d. 1978: behavioral pattern of barren-ground caribou of the central arctic herd adjacent to the trans-alaska oil pipeline. m.s. thesis, university of alaska fairbanks. rominger, e. m . , allen-johnson, l. & oldemeyer, j. l. 1994: arboreal lichen in uncut and partially cut subalpine fir stands in woodland caribou habitat, northern idaho and southeastern british columbia. for. ecol. manage. 70(1-3), 195-202. russell, d. e. & martell, a. m. 1985: influence of the dempster highway on the activity of the porcupine caribou herd. in a. m. martell & d. e. russell (eds.): caribou and human activity. proceedings of the first north american caribou workshop, whitehorse, y. t . , 1983. pp. 22-26. ottawa: canadian wildlife service. shideler, r. t. 1986: impacts of human developments and land use on caribou: a literature review. vol. 2. impacts of oil and gas development on the central arctic herd. tech. rep. 86-3. alaska dept. fish and game, habitat div. shideler r. t., robus j . f., winters, j. f. & kuwada, m. 1986: impacts of human developments and land use on caribou: a literature review. vol. i. a worldwide perspective. tech. rep. 86-2. alaska dept. fish & game, habitat div. shtil’mark, f. r. 1984: ecological niche of wild reindeer in the taiga in relation to human influence on forest landscapes. in e. e. syroechovskii (ed.): wild reindeer of the soviet union. proceedings of the first interdepartmental conference on preservation and rational utilization of wild reindeer, 1974. pp. 95-98. new delhi: amerind publ. shtil’mark, f. r. & azarov, v. i. 1 9 8 4 wild reindeer of the konda river basin. i n e. e. syroechovskii (ed.): wild reindeer of the soviet union. proceedings of the first interdepartmental conference on preservation and rational utilization of wild reindeer, 1974. pp. 180-1 82. new delhi: amerind publ. skoog, r. 0. 1968: ecology of the caribou (rangifer tarandus granti) in alaska. ph.d. diss., university of california berkeley. ann arbor, mi, university microfilms, inc. skrobov, v. d. 1984: human intervention and wild reindeer. in e. e. syroechovskii (ed.): wild reindeer of the soviet union. proceedings of the first interdepartmental conference on preservation and rational utilization of wild reindeer, 1974. pp. 90-94. new delhi: amerind publ. smith, w. t. 1988: effects of hunting with the use of snowmachines on movements of western arctic herd caribou, seward peninsula, alaska. proceedings of the third north american caribou workshop. wildl. tech. bull. 8, 21 1-219. alaska dept. of fish and game. smith, w. t. & cameron, r. d. 1983: responses of caribou to industrial development on alaska’s arctic slope. acra zool. fenn. 1 7 5 , 4 3 4 5 . smith, w. t., cameron, r. d. & reed, d. j. 1994: distribution and movements of caribou in relation to roads andpipelines, kuparuk development area, 1978-90. wildl. tech. bull. 1 2 . alaska dept. of fish and game. sokol’skii, s. m . 1984: wild reindeer of the upper reaches of the pechora river. in e. e. syroechovskii (ed.): wild reindeer of the soviet union. proceedings of the first interdepartmental conference on preservation and rational utilization of wild reindeer, 1974. pp. 172-175. new delhi: amerind publ. spaling, h. & h i t , b . 1993: cumulative environmental change: conceptual frameworks, evaluation approaches, and institutional perspectives. environ. manage. 17, 587-600. spaling, h. & smit, b. 1995: a conceptual model of cumulative environmental effects of agricultural land drainage. agric. ecosyst. enuiron. 53, 99-108. stevenson, s. k. 1 9 9 0 managing second-growth forests as caribou habitat. rangifer, spec. issue 3, 139-144. surrendi, d. c. & debock, e. a. 1976: seasonal distribution, population, status and behaviour of the porcupine caribou herd. edmonton: canadian wildlife service, western and northern region. syroechkovski, e. e. 1984: overview of the problem of wild reindeer in the soviet union. in e. e. syroechovskii (ed.): wild reindeer of the soviet union. proceedings of the first interdepartmental conference on preservation and rational utilization of wild reindeer, 1974. pp. 6-44. new delhi: amerind publ. syroechkovski, e. e. 1990: reindeer in the ussr: problems of protection and rational use. rangifer, spec. issue 3 , 4 2 3 4 3 2 . tracy, d. m. 1977: reactions of wildlife to human activity along mount mckinley national park road. m.s. thesis, university of alaska. truett, j. c., senner, r. g . b., kertell, k., rodrigues, r. & pollard, r. h. 1994: wildlife responses to small-scale disturbances in arctic tundra. wildl. soc. bull. 22, 3 17-324. tyler, n. j . c. 1991: short-term behavioural responses of svalbard reindeer rangifer tarandus platyrhynchus to direct provocation by a snowmobile. biol. conserv. 56, 179-194. valkenburg, p. & davis, j. l. 1985: the reaction of caribou to aircraft: a comparison of two herds. in a. m . martell & d. e. russell (eds): caribou and human activity. proceedings of the first north american caribou workshop, whitehorse, y.t., 1983. pp. 7-9. ottawa: canadian wildlife service. 12 response o f r e i n d e e r and c a r i b o u t o human activities villrna. l. 1975: plenary session: potential impact of acceler ated northern development o n caribou and reindeer popula tionr and ecology the scandinavian viewpoint. i n i.uick et al. (eds.): prucrrditigs uf the firsr inrrrtiatiunirl reindeer/ caribou s.vrnpo~iirrri. f~iirbanks. alasku, 1972. biol. pap. utiirz. alaska, spec. rep. i , +9. vistness. i. 1999: avoidance of cabins and power transniissioti lines bx wtnidornesricared reindeer drrrirrg calving. m.s. thesis. agricultural ijniversity of norway. walah, n. e.. griffirh. b. & mccabe. t. r . 1995: use of a stochastic population model to predict growth of the porcupine caribou herd. j. w i l d . manage. 59. 262-272. white. r . g . 1983: foraging patterns and their multiplier effects on productivity of northern ungulates. oikos 40, 377-384. wolfe et al. 2000: polar rerenrrh 19(1). 63-73 white, r. g. 1992: kutrition in relation to season. lactation. and growth of north temperate deer. i n r . d. brown (ed.): the biulugy u f d e r r . pp. 407-417. new york: springer. whitten, k. r. & cameron, r . d. 1983: movements of collared caribou, rotigifer roraruiur. in relation to petroleum devel opment on the arctic slope of alaska. can. field-nar. 97, 133146. whitten, k . r. 8r cameron, k. d. 1985: distribution ofcaribou calving in relation to the prudhoe ray oil field. i n a. m. manrll & d. e. russell (eds): caribou mid human activir?. proceedings uf rhe first north american caribou workshop. whirehorrr. y . t . . lyr.7. pp. 35-39. ottawa: canadian wild life service. 73 dust travels up to 1 km from the haul road in northern alaska, spring 1994. it settles on the snow surface where it has several effects, including reducing albedo (surface reflectance) leading to early melting in springtime and excessive thawing of frozen ground. photo: c. gubala. in the vast yamal region, industrial disturbance, such as sand quarrying (seen here july 1995), seems minor. nonetheless, as nenets reindeer herdera point out, developers take the best lands higher, drier ground for infrastructure. in an area as flat as yamal, dominated by mires and lakes, this puts unsustainahle pressure on the remaining relatively high ground, exploited by reindeer for insect relief in summer. the end result is that extensive grazing by the reindeer themselves appears to he negatively affecting pastures. photo: b . forbes. such sites as this abandoned gas test well, central yamal peninsula, june 1993, are widespread throughout yamal and are problematic for several reasons: (i) slow revegetation due to dry, nutrient-poor and unstable sand surfaces; (ii) deflation of s a n d dust to the surrounding area, resulting in the rapid burial of tundra vegetation; (iii) toxic drilling muds often left on the surface; and (iv) rusted metal, broken glass and other trash which can injure reindeer’s hooves. photo: b. forbes. a central arctic herd caribou bull escapes the summer heat in the shade of an oil processing facility at prudhoe bay, alaska. while caribou cows generally avoid oil fields during calving, animals commonly utilize building shade and raised gravel pads for insect and heat relief in the summer. photo: g. kofinas. relatively alkaline (ph ca. 8.0) road dust, as seen here o n southern yamal, july 1995, alters substrate chemistry and patterns of nutrient content in vascular and non-vascular plants which serve as reindeer forage. road dust has also been reported to significantly reduce the production of cloudbeny (rubus chamaemorus) fruits and mushrooms in the mires adjoining the main transport corridor on southern yamal (see klein, this issue). photo: b. forbes. vuntut gwitchin hunter, lawrence lord of old crow, yukon, takes aim on the porcupine river. hunting from boats is common for those communities intercepting caribou at river crossings, and typically results in a more efficient, less wasfefui harvest. photo: g. kofinas. 74 cratering behaviour and faecal c:n ratio in relation to seasonal snowpack characteristics in a high-arctic ungulate research article cratering behaviour and faecal c:n ratio in relation to seasonal snowpack characteristics in a high-arctic ungulate larissa t. beumera, øystein varpea,b & brage b. hansenc adepartment of arctic biology, university centre in svalbard, longyearbyen, norway; bakvaplan-niva, fram centre, tromsø, norway; ccentre for biodiversity dynamics, department of biology, norwegian university of science and technology, trondheim, norway abstract snow and ice determine winter forage availability for arctic herbivores. winter precipitation is anticipated to increase, and icing following warm spells and rain-on-snow (ros) are likely to become more frequent. while this may reduce herbivore survival, fecundity and population growth, we can also expect behavioural and dietary responses. here, we tested predictions from optimal foraging theory on how changing snowpack conditions influence choice of feeding craters and diet quality in a large generalist herbivore, the wild svalbard reindeer. snow and ice conditions over winter 2012/13 (a ‘normal’ winter with little ros and icing) were measured in reindeer feeding craters, in paired controls one metre away and in fixed control sites. on average, feeding craters had less snow and integrated ram hardness (irh, the force needed to reach the ground), but not less ice, than nearby controls. however, on this fine spatial scale, reindeer tended to select for microhabitat with worse snowpack conditions up to a certain level of snow (ca. 10 cm), ice (0.5 cm) and irh (250 kg cm) in the nearby controls, reflecting the trade-off between selection for forage abundance versus accessibility in a sparsely vegetated environment. in this lichen-free system, faecal c:n ratios increased during winter as forage accessibility was increasingly restricted by snow, possibly indicating a reduction in diet quality due to changes in diet composition. our study suggests that snowpack depth and hardness largely determine svalbard reindeer feeding behaviour and diet quality during the course of a winter season. keywords climate change; foraging behaviour; icing; herbivore; optimal foraging theory; rangifer tarandus abbreviations aicc: akaike information criterion corrected for small sample sizes; c:n: carbon to nitrogen ratio; id: identification number; irh: integrated ram hardness; lmm: linear mixed model; ros: rain-on-snow; sd: standard deviation; se: standard error the arctic is considered one of the most sensitive regions to climate change, with rising temperatures, changing patterns of precipitation and more frequent extreme weather events in many regions (amap 2011; stocker et al. 2013; serreze et al. 2015). especially during winter, models predict further increases in temperature and changes in precipitation patterns at high northern latitudes over the next few decades (rennert et al. 2009; stocker et al. 2013; koenigk et al. 2015), and increased attention has been given to factors that influence winter forage accessibility in arctic ungulates such as reindeer and caribou (rangifer tarandus; reviewed in tyler 2010). snow is known to be a major behavioural constraint for ungulates – its depth, density, layer structure and hardness strongly influence the energy investment required to reach the plants and lichens beneath (fancy & white 1987) and can be a significant barrier to foraging (skogland 1978, 1984). especially in tundra regions, strong winds can also have a hardening effect on the snowpack (collins & smith 1991). thus, snow characteristics have been shown to strongly affect the behaviour (e.g., adamczewski et al. 1988; johnson et al. 2001; lundmark & ball 2008; loe et al. 2016) and population dynamics of northern ungulates (sæther 1997; kumpula & colpaert 2003). especially for reindeer and caribou, ice can also block access to vegetation or increase the energetic costs to excavate it. thaw–freeze events or ros can cause ice layers to develop as crust ice, within the snowpack or as solid ice on the ground. in the high arctic, where vegetation is generally of very low stature, ground ice can completely cover the vegetation (hansen et al. 2010). such feeding conditions can lead to starvation-related declines in winter body mass (albon et al. 2016), survival (solberg et al. 2001) and fecundity (stien et al. 2012), with consequences for population dynamics (parker et al. 1975; kohler & aanes 2004; grenfell & putkonen 2008; miller & barry 2009; hansen et al. 2011; hansen et al. 2013). because of these snow and ice constraints, the winter feeding behaviour of northern ungulates is constantly influenced by trade-offs between the quality, quantity and accessibility of food plants (e.g., skogland 1984; sæther & andersen 1990; johnson et al. 2001; hansen contact larissa t. beumer larissa_beumer@hotmail.com department of arctic biology, university centre in svalbard, po box 156, 9171 longyearbyen, norway supplemental data for this article can be accessed here. polar research, 2017 vol. 36, 1286121 https://doi.org/10.1080/17518369.2017.1286121 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://dx.doi.org/10.1080/17518369.2017.1286121 http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1286121&domain=pdf et al. 2010). optimal foraging theory (westoby 1974; stephens & krebs 1986) predicts that large generalist herbivores will trade forage quality for quantity (or accessibility) when resource levels are low (e.g., vivås & sæther 1987; sæther & andersen 1990). the underlying rationale is that herbivores can afford to be selective when resource levels are high, implying that they can optimize their nutrient uptake, whereas they become more opportunistic when resource levels are low and energy levels become the critical factor for diet optimization (skogland 1984). few studies have been able to test these predictions in the wild, where animal– habitat interactions and nutritional behaviour reflect trade-offs between many variables, including predator pressure (parker 2003). high-arctic svalbard represents a suitable model system as many potentially confounding factors such as predators, insect harassment, hunting, human infrastructure and interspecific competition for food are absent or negligible. it is also well suited for studying impacts of ros and icing, as abovezero periods and ros events occur during many winters as a result of svalbard’s oceanic climate (hansen et al. 2014). in this study, we took advantage of these features to test predictions derived from optimal foraging theory on how changes in forage accessibility influence foraging decisions and diet quality in a large generalist herbivore, the predator-free wild svalbard reindeer (r. t. platyrhynchus). more specifically, we examined responses to changing snowpack conditions by relating variation in feeding crater characteristics to control measurements at different spatial scales. furthermore, we used faecal c:n ratio (as an inverse proxy of nitrogen content and hence diet quality in large herbivores; leslie & starkey 1985) to test whether reduced forage accessibility due to worsening snow and ice conditions during the course of a winter may cause reduced selection for high-quality forage (macarthur & pianka 1966; sæther & andersen 1990). material and methods study area the arctic archipelago of svalbard is located between 74° and 81°n and 10° and 35°e. this study was conducted during the winter of 2012/13 in adventdalen, a glacially eroded u-shaped valley in central spitsbergen, svalbard’s largest island (fig. 1). longyearbyen, svalbard’s largest settlement, is located within adventdalen. the climate in adventdalen can be characterized as high-arctic under oceanic influence. despite the high latitude, temperatures are often relatively mild during winter due to the warm west spitsbergen current (piechura et al. 2001). short periods of above-zero temperatures can occur throughout the winter. at sea level, snow usually covers the area from early october until the beginning of june. with a mean yearly precipitation of only about 190 mm (for standard normal period 1961–1990; www.eklima. met.no), adventdalen is one of the driest areas in svalbard. the common combination of dry snow and open tundra makes drifting or blowing snow an important factor in local snow distribution. south-easterly winds are dominant during winter, resulting in a typically thin snow cover and much of the snow being blown away into the sea. trees and shrubs are absent in svalbard, providing only a low (5–10 cm) field-layer available as food for herbivores (rønning 1996; jónsdóttir 2005). study species we studied animals of the adventdalen reindeer subpopulation, which has recently fluctuated around 1000 individuals (hansen et al. 2013). the svalbard reindeer is a wild subspecies endemic to svalbard. it has several adaptations to extreme winter conditions. during summer, the animals build up stores of body fat that are considerable yet not sufficient alone to ensure winter survival and foetus development (tyler 1986, 1987). we therefore assume that winter diet and behaviour have been under strong selection. in contrast to most other reindeer populations, they have small home ranges and usually do not undertake long-distance migrations (tyler & øritsland 1989). this sedentary behaviour reduces their energy demands for locomotion, which can be substantial in other caribou and reindeer populations travelling longer distances (fancy & white 1987). like other reindeer and figure 1. the study area adventdalen in central spitsbergen, svalbard (inset), including the city of longyearbyen and the airport, where the nearest meteorological data are recorded. dark grey lines are roads, black crosses are the fixed control sites (two measurement sites per cross) and white dots represent the position of measured feeding craters. altitude is shown in 250 m intervals. glaciers are shown in white. map courtesy of the norwegian polar institute. 2 l. t. beumer et al. http://www.eklima.met.no http://www.eklima.met.no caribou (tushinskii 1949, in bergerud & nolan 1970; bergerud 1974; laperriere & lent 1977), the svalbard reindeer show a remarkable ability to detect ice-free microhabitat under the snowpack, which has been attributed to their olfactory senses (hansen et al. 2010). the concave-shaped hooves have sharp foreedges, with which they can break through ice layers and scrape away the snow while feeding (skogland 1978). in doing so, especially in deeper snow, they dig characteristic ‘feeding craters’ (supplementary fig. s1a, b). svalbard reindeer are generalist herbivores in an extreme low-productivity environment. they feed on most available plant species and have been shown to adjust their feeding preferences opportunistically to changing conditions (staaland et al. 1993; bjune 2000; bjørkvoll et al. 2009; hansen & aanes 2012). their main winter diet consists of graminoids, polar willow (salix polaris) and mosses, complemented by other common plant groups (bjørkvoll et al. 2009). unlike for most other subspecies of r. tarandus, mosses can be an important dietary component in winter in spite of their low digestibility (staaland et al. 1983; bjørkvoll et al. 2009). it is assumed that this high intake of mosses in svalbard is due to a low availability of lichens – the preferred food source of reindeer and caribou in winter elsewhere (skogland 1984; van der wal et al. 2000). important winter habitats for svalbard reindeer are exposed areas, in this study defined as ridge and sub-ridge habitats, where little snow accumulates. ridge habitats are characterized by only scattered vegetation cover, with dominating species being s. polaris and white dryad (dryas octopetala). sub-ridge habitats have slightly more snow accumulation and are dominated by the sedge luzula confusa as well as the grasses poa alpigena and p. alpina. the svalbard reindeer is subject to only negligible predation; a handful of killings by polar bears (ursus maritimus) have been reported (derocher et al. 2000). insect harassment is minimal (reimers 1980), as is interspecific competition: the svalbard rock ptarmigan (lagopus muta hyperborea) is the only other over-wintering herbivore. survival and reproduction rates are highly variable between years (solberg et al. 2001; stien et al. 2012) because of density-dependence and variation in climatic conditions during winter (reimers 1983; aanes et al. 2000; solberg et al. 2001; kohler & aanes 2004; hansen et al. 2011; hansen et al. 2013), but also during summer (aanes et al. 2002; hansen et al. 2013). data collection daily air temperature and precipitation at the svalbard airport (24 m asl) from october 1975 until june 2013 were obtained from the norwegian meteorological institute (www.eklima.met.no). precipitation that fell at air temperatures above 1°c was considered rain (see, e.g., stien et al. 2012). winter was defined as october in year t − 1 to april in year t. to estimate the overall temporal changes in feeding conditions during the course of the winter 2012/ 13, we measured snow and ice thicknesses at 24 fixed control sites distributed at 12 locations (fig. 1). the locations followed a spatial hierarchical design, covering two areas with potentially different climatic conditions (coastal versus inland) at different elevations (low, <100 m asl; intermediate, 100–200 m asl; high, >200 m asl). at each location, two snow profiles at about 5–10 m distance apart, one each in ridge and sub-ridge habitat, were excavated. for each profile, snow depth (measured to the nearest 0.5 cm) and ground ice thickness (measured to the nearest 0.5 cm) as well as number of ice layers within the snowpack and their summed thickness (hereafter referred to as ‘ice thickness’) were recorded. from december on, a ramsonde penetrometer was also used to measure the hardness of the snowpack (skogland 1978; hansen et al. 2010). the ramsonde has a conical tip and penetrates the snow cover in response to a load (1 kg), which is dropped from a defined height (55 cm). each time the load is dropped, the depth of the penetration into the snow is noted, until the ramsonde reaches ground (or ground ice, which is usually impenetrable). the resistance to penetration of the snow cover (‘ram hardness’) (kg) is given as: h rð þ ¼ p � n � h d þ q (1) where p = weight of load (kg), n = number of load drops, h = height of drop (cm), d = snow depth (cm) and q = total weight of the ramsonde (kg) (skogland 1978). the total force needed to penetrate the entire snowpack (irh; kg cm) can then be calculated as: irh ¼ d � h rð þ (2) (e.g., nellemann 1998; hansen et al. 2010). in this study we were mainly interested in the total force needed to reach the ground (i.e., the vegetation) and, hence, we only consider irh. fixed control site locations were relocated using global positioning system waypoints, and stakes were used for marking the locations to avoid trampling that might affect later measurements. the exact location of the measurement was altered with 0.5 m (towards north, north-east, east, etc.) between each measurement. in total, seven measurements (hereafter referred to as ‘rounds’) that covered all 24 fixed control sites were performed over the winter, one of which was done after the beginning of snow melt in spring. each round was completed within one, maximum two days. because the ramsonde was not available from the beginning of the study, the first polar research 3 http://www.eklima.met.no two rounds of measurements did not include irh values. we also performed snow and ice measurements in reindeer feeding craters located by spotting feeding reindeer from a car along a road transect in adventdalen. this choice of transect was mainly based on the logistical challenges related to the dark polar night season. craters occurred either along tracks of individual reindeer or in clusters where several craters from one or more individuals aggregated within a patch (see hansen et al. 2010). both versions will hereafter be commonly referred to as a ‘crater group’. measurements were made wherever animals or fresh craters were encountered along the car transect. visibility for this purpose was particularly limited during the polar night: from the beginning of november to the end of january (supplementary fig. s1c). as the animals are not marked, some degree of pseudo-replication (i.e., lack of independence between data points) may have occurred. however, the sedentary behaviour largely ensures that different individuals were sampled within a day or pooled days (for comparison with each fixed control measurement round, see above). in most cases, up to five craters were measured per crater group. for snow profile measurements, the least disturbed crater edges with the clearest profile were used; ramsonde measurements were made in undisturbed snow as close to that edge as possible while avoiding an ‘edge effect’. following hansen et al. (2010), at each analysed feeding crater one paired nearby control location was measured at 1 m distance from the crater in a random direction. these controls were used to investigate crater selection at a small scale, i.e., the feeding station level. overall, 114 craters and an equal number of controls were measured in 24 crater groups, 16 (four crater groups) of which were measured after the beginning of spring (here defined as 1 may). all crater sites were below 100 m asl (parts of the population also utilize higher altitudes, but these are difficult to access and were not included). as it was too dark during parts of the winter season to identify the gender, age and number of reindeer present, these variables are not considered in the analyses. ramsonde measurements in feeding craters and nearby controls were not performed before january 2013. in each crater group, we sampled one to five fresh faeces (mean = 2.9, sd = 1.7; each sample including a minimum of five pellets) for estimation of diet quality. the c:n ratio is a proxy of diet quality, with high c:n ratio in faeces generally reflecting a low nitrogen content and diet quality (leslie & starkey 1985) as a low content of proteins (important for animal nutrition; parker et al. 2009) results in low nitrogen in the faeces. lichens are low in nitrogen, yet a preferred winter food source in many reindeer and caribou populations because of their high energy content (danell et al. 1994). however, as lichen are virtually absent in svalbard, we assume that c:n ratio represents an adequate measure of variation in diet quality. in several cases the defecation itself was not observed, yet we feel confident that the faecal samples were from the animals that had made the respective craters. faeces samples were also collected in spring, during the snowmelt, to quantify whether the c:n ratio changes as snow-free habitat is exposed and plants start producing fresh biomass. spring samples were only from individuals observed to defecate. in total, 66 faecal samples were collected, all of which could be linked temporally to one of the seven sampling rounds (see above). samples were stored in the freezer. before analysis, they were dried at 60°c overnight. from each sample, 3–5 mg of faecal material were packed into tin capsules. the carbon and nitrogen contents were analysed by thermal decomposition using an ea 1110 chns-o elemental analyser (ce instruments). data analyses to analyse how snow and ice conditions changed during the course of the winter, we used linear mixed effects models to regress measures from the fixed control sites against a number of explanatory environmental factors (lmm with a gaussian family and identity link; lmer function in package lme4, r core team 2013). a separate lmm was run for snow depth, ice thickness and irh including the following fixed effects: area (coast or inland), elevation (high, medium, low), habitat (ridge or sub-ridge) and ‘round’ (as factor). location was included as random intercept effect. for irh, one extreme outlier of 4455 kg cm in round 4 caused serious residual problems and was removed. for extraction of parameter estimates representing the condition changes between rounds, low elevation and inland area were defined as intercept as they best resembled the areas where reindeer crater and faecal data were sampled. to assess fine-scale feeding crater selection, we analysed feeding crater conditions relative to nearby controls (1 m distance). we regressed snow depth in feeding craters (the sample unit) against snow depth in the paired nearby control (fixed effect) using an lmm with gaussian family and identity link, and crater group id as random intercept. similar analyses were run separately for ice thickness in the snowpack and irh. ground ice was largely absent in craters and occurred only rarely in nearby controls, and then generally as a thin and discontinuous layer. for simplicity, we therefore disregarded ground ice in these analyses of fine-scale selection. we also examined how temporal changes in feeding crater characteristics corresponded with overall 4 l. t. beumer et al. changes in the conditions measured in the fixed control sites, represented by the ‘round’-specific parameter estimates of snow depth and ice thickness (see analysis above). similar lmms as for the fine-scale selection above were run, i.e., snow depth or ice thickness in feeding craters (sampling unit) as a function of the respective round’s parameter estimate of snow depth or ice thickness, respectively, and with crater group id as random intercept effect. irh was not analysed here as data were missing from the fixed sites in the first rounds. finally, we tested how faecal c:n ratio changed with temporal changes in the conditions measured in fixed control sites during the course of the winter. this was to investigate whether this diet quality proxy would drop in response to worsening snowpack conditions, which reduced the accessibility of forage, assuming that the animals would trade forage quality for lower energetic costs of digging. (to avoid confounding of spatial and temporal effects, faecal c:n ratios were not related to the snow and ice conditions in craters.) the median c:n value from faeces belonging to the same crater group was used for further analysis to avoid pseudo-replication. a linear regression was applied with c:n ratio as a function of the respective round’s parameter estimates of snow depth and ice thickness, and their interaction. the best model was determined using aicc corrected for small sample sizes, where the candidate model with the lowest aicc value is regarded the best fitting model, but all models with a δaicc of <2 were considered (burnham & anderson 2002). data from spring (after 1 may; n for faeces = 16, n for craters/controls = 16 from four crater groups) were only used qualitatively to evaluate c:n ratios as a proxy of diet quality. because of difficulties in separating the effect of easier accessibility of vegetation due to snowmelt versus the appearance of fresh vegetation growth, these data were excluded from statistical analyses. analyses were run with r version 3.0.2 (downloaded on 25 september 2013; r core team 2013). p values were generated with the lmertest package in r. results fifteen days with temperatures above 1°c were recorded in the study winter (fig. 2), with rain >0.1 mm occurring on four days. the summed precipitation (116 mm) was close to the 1976–2012 median (106 mm); however, the amount falling as rain (9 mm) was below the median of 13 mm. the greatest changes in snow and ice conditions occurred between mid–late december and mid-january as a result of heavy snowfall in december, followed by some small rain events and periods of relatively mild temperatures in early january (fig. 2). table 1. spearman-correlation table for: (a) snow and ice parameters (irh) measured in reindeer feeding craters (n = 98; n = 37 for irh), above the diagonal; and (b) for snow and ice parameters measured in fixed control sites (n = 144; n = 96 for irh), below the diagonal. statistically significant correlations are marked by * (p < 0.05) or ** (p < 0.001). snow depth (cm) ground ice (cm) number of ice layers ice thickness (cm) irh (kg cm) snow depth – 0.08 0.42** 0.42** 0.62** ground ice −0.23* – −0.21* −0.21* −0.15 number of ice layers 0.44** −0.01 – 0.95** 0.28* ice thickness 0.40** 0.04 0.98** – 0.49** irh 0.82** −0.16 0.50** 0.49* – table 2. results for model of temporal changes in overall conditions based on measurements in fixed control sites. separate linear mixed models were run for snow depth, ice thickness and irh including area (coast or inland), elevation (high, medium, low), habitat (ridge or sub-ridge) and ‘round’ (as factor) as fixed effects and location as random intercept effect. values show parameter estimates ± se (except for variance values for random effects, which are shown with sd). the intercept was defined as ‘area = inland’, ‘elevation = low’, ‘habitat = ridge’ and ‘measurement round = 1’ (round = 3 for irh, as ramsonde measurements were not performed until round 3). note that model for ice thickness is on the log-scale (with addition of 1). snow depth (cm) ice thickness (cm) irh (kg cm) intercept 12.8 ± 8.5 0.37 ± 0.11 436 ± 350 (p = 0.14) (p < 0.01) (p = 0.23) measurement round 2 4.27 ± 4.41 −0.13 ± 0.10 × (p = 0.34) (p = 0.17) measurement round 3 14.2 ± 4.4 −0.27 ± 0.10 × (p < 0.01) (p < 0.01) measurement round 4 25.7 ± 4.4 0.31 ± 0.10 814 ± 131 (p < 0.001) (p < 0.01) (p < 0.001) measurement round 5 23.4 ± 4.4 0.46 ± 0.10 851 ± 131 (p < 0.001) (p < 0.001) (p < 0.001) measurement round 6 26.0 ± 4.4 0.11 ± 0.10 639 ± 131 (p < 0.001) (p = 0.27) (p < 0.001) area −2.53 ± 7.13 0.045 ± 0.080 −205 ± 305 (coastal) (p = 0.73) (p = 0.58) (p = 0.51) elevation −3.85 ± 8.73 −0.26 ± 0.10 −336 ± 374 (intermediate) (p = 0.66) (p < 0.05) (p = 0.38) elevation −13.04 ± 8.73 −0.30 ± 0.10 −251.10 ± 373.50 (high) (p = 0.15) (p < 0.01) (p = 0.51) habitat 14.9 ± 7.1 0.13 ± 0.08 456 ± 305 (sub-ridge) (p = 0.05) (p = 0.12) (p = 0.15) variance ‘waypoint id’ 266.0 0.02 50,5951 (sd = 16.31) (sd = 0.14) (sd = 711.3) variance ‘residuals’ `233.6 0.11 19,9295 (sd = 15.28) (sd = 0.33) (sd = 446.4) polar research 5 snow depth, number of ice layers, ice thickness and irh were positively correlated both across feeding craters and in fixed controls, while ground ice was weakly negatively correlated with number of ice layers and ice thickness in craters and with snow depth in fixed controls (table 1). in the models estimating temporal changes in conditions, we found that snow tended to be deeper in sub-ridge than ridge habitat and ice thickness declined with increasing elevation, while there was no apparent area (coast versus inland) effect (table 2). little ground ice was recorded in feeding craters (present in five out of 98), nearby controls (22 out of 98) and fixed control sites (11 out of 144). most ground ice found was thin (<1 cm). therefore, ground ice was not included in models assessing cratering selection and changes in diet quality. the snow depths and ice thicknesses (in snowpack) in feeding craters were positively related to changes in the fixed controls’ conditions (i.e., round-specific model estimates of the respective parameter; table 3; fig. 3a, b). however, while reindeer selected feeding craters with on average less snow than the fixed control sites, craters had on average thicker ice than the controls. crater group id as random effect explained 30% of the added variance in snow depth and 41% in ice thickness, indicating that much of the variation in crater values was due to variation between local feeding spots or groups of animals. compared with nearby (1 m) controls, feeding craters had less snow (paired t-test: t = 4.1, p < 0.001, df = 97) and lower irh (t = 2.4, p < 0.05), but not less ice (t = 0.96, p = 0.34). this indicates that on average, the animals selected against deep snow and high irh at the fine spatial scale. snow depth in feeding craters increased with snow depth in the nearby controls (table 4, fig. 3c) but rarely exceeded 25–30 cm. the modelled regression slope of snow in craters versus nearby controls was significantly less than one and suggested that reindeer selected for deeper snow than the immediate surroundings up to some low level (ca. 10 cm snow 0 5 10 15 20 25 p r e c ip it a t io n ( m m ) (a) −25 −20 −15 −10 −5 0 5 10 m e a n t e m p e r a t u r e ( ° c ) 0 20 40 60 80 100 s n o w d e p t h ( c m ) (b) 0 1 2 3 4 g r o u n d i c e ( c m ) (c) 0 1 2 3 4 5 6 s u m m e d i c e t h ic k n e s s ( c m ) (d) 0 500 1000 1500 2000 2500 3000 3500 i r h ( k g * c m ) *(e) 15 20 25 30 35 40 c : n r a t io (f) 40 42 44 46 48 50 52 2 4 6 8 10 12 14 16 18 20 22 24 26 calender week figure 2. seasonal changes in environmental conditions in fixed control sites as well as in reindeer feeding craters and in the c:n ratio of reindeer faeces. (a) daily weather, measured at svalbard airport, from october 2012 to june 2013: mean temperature, precipitation as snow (light grey bars) and as rain (dark bars). data source: norwegian meteorological institute. dotted horizontal line marks the 1°c threshold for precipitation being classified as rain. (b–e) changes in snow depth, ground ice, ice thickness (not including ground ice) and irh at fixed control sites (dark boxplots) and in reindeer feeding craters (light grey boxplots; grouped to weeks). (f) changes in c:n ratio from fresh faeces sampled around the craters. dashed vertical lines indicate the beginning of the spring season (here defined as 1 may). 6 l. t. beumer et al. depth in controls), where selection apparently shifted sign. smoothed regressions (loess and lowess curves) largely confirmed this pattern (fig. 3c). ice thickness in feeding craters only occasionally exceeded 3 cm (fig. 3d) and increased with increasing ice thickness in nearby controls (table 4, fig. 3d). however, this relationship was driven by the prevailing cases with no ice: when excluding these cases the modelled slope was significantly different from one and even tended to be negative. for irh, a similar pattern of fine-scale selection was found as for snow depth, with a positive effect of irh in the nearby control on irh in the feeding crater and a shift in the crater selection from selecting ‘worse’ to selecting ‘better’ when the irh in nearby controls reached a threshold of about 250 kg cm (fig. 3e). crater group id as random effect explained 46% of the added variance in snow depth, 68% in ice thickness and 32% in irh. in the five cases (out of 98) where ground ice was found in cratered sites, it did not form a continuous layer, but rather consisted of a mosaic of ice patches. in all of these cases, vegetation protruded from the ice. in comparison, ground ice was recorded 22 times in the nearby controls (mostly 0.5 cm, maximum 5 cm), indicating avoidance of ground-ice at fine spatial scales (χ2 = 12.4, df = 1, p < 0.001). faecal c:n ratios, which were strongly negatively correlated with nitrogen content (pearson’s r = −0.94, p < 0.001; fig. 4a), increased over the course of the winter, indicating that diet quality decreased as the winter progressed and food accessibility worsened (fig. 2). c:n ratios dropped rapidly when ridges became snow-free and vegetation (including fresh growth) became more available in spring. aicc model selection (supplementary table s1) suggested only one candidate model to be considered: excluding the spring data, the increase in faecal c:n ratios during winter was best explained by snow depth (round-specific estimates from fixed control sites) (α = 20.3 ± 2.2 se with p < 0.001, β = 0.29 ± 0.07 se with p < 0.001, r2 = 0.50, df = 15; fig. 4b). discussion in this study we have demonstrated how cratering choices and a faecal-based diet quality proxy in a high-arctic large herbivore change with worsening snowpack conditions during the course of a winter. while wild svalbard reindeer generally cratered in sites with shallower and less hard snow (but not less ice) than in nearby controls, this fine-scale selection changed sign when conditions were comparatively good (fig. 3). furthermore, as predicted from optimal foraging theory, faecal c:n ratios (our inverse diet quality proxy) increased with a decrease in forage accessibility (fig. 4). despite being based on data from only one winter with a limited sample size, our study provides novel insights into arctic ungulates’ adaptive capacities to respond to climate change and changes in snowpack conditions. at the fine spatial scale, i.e., when comparing craters with nearby controls, we found support for selective behaviour against deep and hard snow, but only above a certain low level. under good conditions – the comparatively shallow or soft snowpack that occurs in early winter – selecting microhabitat with deeper or harder snow than the immediate surroundings might be a strategy to optimize diet quality or intake rates. food plants are increasingly abundant further down on windblown ridges, justifying the slightly higher energetic costs of digging. once conditions worsened with deeper and harder snow, table 3. results for models investigating reindeer cratering selection at the landscape level, by comparing feeding crater values to overall conditions, represented by fixed control sites model estimates (from table 2). linear mixed models were used to test selection for/against snow depth or ice thickness. crater group id was included as random effect. values show parameter estimates ± se (except for variance values for random effects, which are shown with sd). snow depth (cm) ice thickness (cm) intercept 0.08 ± 2.09 −0.05 ± 0.35 (p = 0.97) (p = 0.9) snow depth 0.39 ± 0.06 × (p < 0.001) ice thickness × 1.95 ± 0.51 (p < 0.01) irh (kg cm) × × variance ‘crater group id’ 5.49 0.41 (sd = 2.34) (sd = 0.64) variance ‘residuals’ 12.81 0.6 (sd = 3.58) (sd = 0.77) table 4. results for models investigating reindeer cratering selection at the feeding station level, by relating feeding crater values to nearby (1 m) control locations. linear mixed models were used to test selection for/against snow depth, ice thickness or irh. crater group id was included as random effect. values show parameter estimates ± se (except for variance values for random effects, which are shown with sd). note that models for ice thickness are on the log-scale (with addition of 0.1 in model including zero values). snow depth (cm) ice thickness including zero values (cm) ice thickness excluding zero values (cm) irh (kg cm) intercept 6.99 ± 1.12 −0.44 ± 0.24 0.44 ± 0.15 180.0 ± 45.2 (p < 0.001) (p < 0.1) (p < 0.01) (p < 0.001) snow depth 0.36 ± 0.06 × × × (p < 0.001) ice thickness × 0.23 ± 0.08 −0.09 ± 0.11 × (p < 0.01) (p = 0.44) irh × × × 0.35 ± 0.08 (p < 0.001) variance ‘crater group id’ 9.09 1.01 0.18 10,024 (sd = 3.01) (sd = 1.01) (sd = 0.43) (sd = 100.1) variance ‘residuals’ 10.5 0.48 0.25 21,260 (sd = 3.24) (sd = 0.70) (sd = 0.50) (sd = 145.8) polar research 7 selection shifted sign: there was a selection against deep or hard snowpack, probably at the cost of poorer food abundance or quality. in spite of little icing during the study winter, reindeer avoided cratering in the few sites where vegetation was completely covered by ground ice (see also hansen et al. 2010). this supports the hypothesis that olfactory senses are important when locating food under the snowpack (e.g., bergerud & nolan 1970; bergerud 1974). snow depth in craters rarely exceeded 30 cm (fig. 2). this corresponds well with previous values reported for svalbard reindeer (hansen et al. 2010) as well as caribou in alaska (e.g., collins & smith 1991) and on coats island, canada (adamczewski et al. 1988). although pruitt (1959) and laperriere & lent (1977) suggested that caribou crater in snow with thickness up to around 50–60 cm, and johnson et al. (2000) found craters up to 1 m deep, bergerud & nolan (1970) proposed a limit of 18 cm of snow for smelling forage lichens. most 0.0 0.2 0.4 0.6 0.8 1.0 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 f a e ca l c :n r a tio log(faecal nitrogen content) (a) 10 15 20 25 30 35 40 2 0 2 5 3 0 3 5 4 0 f a e ca l c :n r a tio snow depth (cm) (b) figure 4. faecal c:n ratio in relation to (a) nitrogen content and (b) estimates of temporal changes in snow depth, as measured in fixed control sites throughout the winter season (see table 2). in (b), spring data are excluded. black lines represent model regression line; dashed lines in (b) indicate confidence interval for model regression line. s n o w d e p th in c ra te rs ( cm ) snow depth in fixed controls (cm) (a) ic e t h ic kn e ss in c ra te rs ( cm ) ice thickness in fixed controls (cm) (b) (c) s n o w d e p th in c ra te rs ( cm ) snow depth in near by controls (cm) − 2 − 1 0 1 2 lo g (i ce t h ic kn e ss in c ra te rs ( cm )) log(ice thickness in near by controls (cm)) (d) 0 10 20 30 40 50 0 1 0 2 0 3 0 4 0 5 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 .0 0 .5 1 .0 1 .5 2 .0 2 .5 3 .0 3 .5 0 10 20 30 40 0 1 0 2 0 3 0 4 0 −2 −1 0 1 2 0 500 1000 1500 0 5 0 0 1 0 0 0 1 5 0 0 ir h in c ra te rs ( kg *c m )) irh in near by controls (kg*cm)) (e) figure 3. feeding crater selection by svalbard reindeer at two spatial scales. (a, b) selection at the landscape level: comparison of round-specific snow depth and ice thickness in reindeer feeding craters with conditions in fixed control sites, represented by model estimates. feeding crater data (means with sd) and fixed control sites model estimates (with ses) were grouped to measurement rounds (excluding spring measurements). (c–e) selection at the feeding station level: comparison of snow depth, ice thickness and irh in reindeer feeding craters with paired nearby control spots. note that the positive relationship in (d) was not present when cases with zero ice were removed. in (d) values were jittered to allow better visual interpretation. dashed black lines indicate a slope = 1. black solid lines display model regression lines (tables 3, 4). in (c–e), smoothed regression lines are included (red = lowess, blue = loess). 8 l. t. beumer et al. craters in our study were well within these limits. however, lichens are hardly present in the study area and are not a significant food source for the reindeer (bjørkvoll et al. 2009), and thresholds for smelling plants are not known. irh can be considered a representative proxy for forage accessibility, as it integrates the hardness and thickness of the entire snowpack (skogland 1978), including ice layers. irh in feeding craters rarely exceeded 500 kg cm (median: 263 kg cm), which resembles previously reported values from more icy feeding conditions in svalbard (hansen et al. 2010). in a study of arctic tundra caribou (r. tarandus) on southern baffin island, canada, ferguson et al. (2001) found mean irh in feeding craters to vary spatially between 160 and 601 kg cm. similar values were reported by laperriere & lent (1977) for caribou in north-eastern alaska, while reindeer in mainland norway were feeding on ridges with on average 357–2297 kg cm irh (nellemann 1996). this comparison with other rangifer populations may indicate that, because of the extremely sparse-growing vegetation in the high arctic, the energy expenditure threshold for cratering is low compared with lower latitude areas. in the latter, cratering in deeper and harder snow might still be beneficial as food plants are likely more abundant once the vegetation is accessed beneath the snowpack. faecal c:n ratio is only one of several potential proxies of diet quality in large herbivores (leslie & starkey 1985), and cautious interpretation is needed. however, c:n ratios were almost perfectly negatively correlated with nitrogen content, which is known as a crucial determinant of body condition and reproduction in reindeer and caribou (see e.g., adamczewski et al. 1987; parker et al. 1990; parker et al. 2009). as the snowpack became deeper during the course of the winter, faecal c:n ratios increased. this indicates that even though the reindeer crater in increasingly deeper snow as conditions worsen, the growing energy expenditure (fancy & white 1987) and the trade-off between forage quality, quantity and accessibility (westoby 1974; stephens & krebs 1986) will at some point cause a reduction in diet quality (or food intake rates), as feeding patches with lower-quality or less abundant food plants are selected. in contrast to snow depth, however, we found no effect of ice thickness on faecal c:n ratios, and on average there was no fine-scale selection against ice thickness. this study therefore indicates that during ‘normal’ precipitation winters with (in a svalbard context) little ros and icing – the conditions more typically faced by lowerlatitude rangifer populations (laperriere & lent 1977; nellemann 1996; ferguson et al. 2001) – svalbard reindeer feeding choices and diet quality are constrained by total snowpack depth rather than the few and overall thin ice layers present in the snowpack. the record high number of animals counted in adventdalen during the annual monitoring in the following summer (ims et al. 2014) suggests that mortality during the study winter was low and that the winter feeding conditions supported a high subsequent reproduction rate, as expected in the absence of ground ice (e.g., stien et al. 2012; hansen et al. 2014). in the context of winter climate change and the expected increase in ros and icing (hansen et al. 2014), we therefore encourage future multi-year studies comparing the behavioural and dietary responses to snow and ice under different conditions. around the onset of spring, faecal c:n ratios dropped rapidly with forage accessibility becoming less restricted because of melting of snow, and vegetation becoming easily available. this spring effect potentially also included access to emerging green vegetation (see also råstad 2010), although this effect could not be controlled for in this study. nevertheless, either due to vegetation becoming more accessible or fresh vegetation emerging, the spring drop in faecal c:n ratios represents indirect support for our use of c:n ratios as an inverse proxy of diet quality in this study. trends of earlier onsets of spring have been documented for arctic regions (e.g., moritz et al. 2002; høye et al. 2007; post & forchhammer 2008) and are predicted to continue (amap 2011). the rapid spring effect on faecal c:n ratios (a proxy for diet quality) found here adds to the impression that advancement of spring is overall beneficial for reindeer (tveraa et al. 2013; but see post & forchhammer 2008), possibly counteracting negative effects of deeper snowpack or increased frequencies of icing events on the reindeer’s body condition. in conclusion, this study has demonstrated patterns of variation in cratering choices and a diet quality proxy of svalbard reindeer which are in line with expectations from optimal foraging theory, predicting dynamic foraging trade-offs for northern large herbivores (e.g., skogland 1984; andersen & sæther 1992). hence, diet quality decreases with only slight reductions in forage accessibility, and the selection curve for snow and ice indicates a low-level switch from selecting worse to selecting better conditions than the immediate surroundings. the cratering threshold (in terms of irh) in this high-arctic subspecies appears to be comparatively low, most likely because of the sparse vegetation and associated high cost–benefit ratio of cratering at such high latitudes. given the expected changes in winter climate, with more precipitation and heavy icing events in particular (rennert et al. 2009; hansen et al. 2011; stocker et al. 2013), our results may indicate future changes in the realized winter foraging niche and diet quality. polar research 9 acknowledgements this study was funded by the authors’ institutions and the research council of norway through the polar research programme (216051) and sff-iii program (223257, centre for biodiversity dynamics, norwegian university of science and technology). we would like to thank eike müller for his help in the field and the laboratory, martin mantel for creating the map and everybody else who helped out with the fieldwork. we would also like to thank two anonymous reviewers for their helpful and constructive comments on previous versions of this article. we are furthermore grateful to the norwegian polar institute for providing the map material and the norwegian meteorological institute for providing the weather data. disclosure statement no potential conflict of interest was reported by the authors. funding this work was supported by the research council of norway through the polar research programme (grant 216051) and sff-iii (223257). references aanes r., sæther b.-e. & øritsland n.a. 2000. fluctuations of an introduced population of svalbard reindeer: the effects of density dependence and climatic variation. ecography 23, 437–443. aanes r., sæther b.-e., smith f.m., cooper e.j., wookey p. a. & øristland n.a. 2002. the arctic oscillation predicts effects of climate change in two trophic levels in a high-arctic ecosystem. ecology letters 5, 445–453. adamczewski j.z., gates c.c., hudson r.j. & price m.a. 1987. seasonal changes in body composition of mature female caribou and calves (rangifer tarandus groenlandicus) on an arctic island with limited winter resources? canadian journal of zoology 65, 1149–1157. adamczewski j.z., gates c.c., soutar b.m. & hudson r.j. 1988. limiting effects of snow on seasonal habitat use and diets of caribou (rangifer tarandus groenlandicus) on coats island, northwest territories, canada. canadian journal of zoology 66, 1986–1996. albon s.d., irvine r.j., halvorsen o., langvatn r., loe l.e., ropstad e., veiberg v., van der wal r., bjørkvoll e.m., duff e.i., hansen b.b., lee a.m., tveraa t. & stien a. 2016. contrasting effects of summer and winter warming on body mass explain population dynamics in a food-limited arctic herbivore. global change biology, doi: 10.1111/gcb.13435 amap (arctic monitoring and assessment programme) 2011. snow, water, ice and permafrost in the arctic (swipa): climate change and the cryosphere. oslo: arctic monitoring and assessment programme. andersen r. & sæther b.-e. 1992. functional-response during winter of a herbivore, the moose, in relation to age and size. ecology 73, 542–550. bergerud a.t. 1974. relative abundance of food in winter for newfoundland caribou. oikos 25, 379–387. bergerud a.t. & nolan m.j. 1970. food habits of handreared caribou rangifer tarandus l. in newfoundland. oikos 21, 348–350. bjørkvoll e., pedersen b., hytteborn h., jónsdóttir i.s. & langvatn r. 2009. seasonal and interannual dietary variation during winter in female svalbard reindeer (rangifer tarandus platyrhynchus). arctic, antarctic and alpine research 41, 88–96. bjune a.e. 2000. pollen analysis of faeces as a method of demonstrating seasonal variations in the diet of svalbard reindeer (rangifer tarandus platyrhynchus). polar research 19, 183–192. burnham k.p. & anderson d.r. 2002. model selection and multi-model inference: a practical information-theoretic approach. 2nd edn. new york: springer. collins w.b. & smith t.s. 1991. effects of wind-hardened snow on foraging by reindeer (rangifer tarandus). arctic 44, 217–222. danell k., utsi p.m., palo r.t. & eriksson o. 1994. food plant selection by reindeer during winter in relation to plant quality. ecography 17, 153–158. derocher a.e., wiig o. & bangjord g. 2000. predation of svalbard reindeer by polar bears. polar biology 23, 675–678. fancy s.g. & white r.g. 1987. energy expenditures for locomotion by barren-ground caribou. canadian journal of zoology 65, 122–128. ferguson m.a.d., gauthier l. & messier f. 2001. range shift and winter foraging ecology of a population of arctic tundra caribou. canadian journal of zoology 79, 746–758. grenfell t.c. & putkonen j. 2008. a method for the detection of the severe rain-on-snow event on banks island, october 2003, using passive microwave remote sensing. water resources research 44, w03425, doi: 10.1029/ 2007wr005929. hansen b.b. & aanes r. 2012. kelp and seaweed feeding by high-arctic wild reindeer under extreme winter conditions. polar research 31, article no. 17258, doi: 10.3402/ polar.v31i0.17258. hansen b.b., aanes r., herfindal i., kohler j. & sæther b.-e. 2011. climate, icing, and wild arctic reindeer: past relationships and future prospects. ecology 92, 1917–1923. hansen b.b., aanes r. & sæther b.-e. 2010. feeding-crater selection by high-arctic reindeer facing ice-blocked pastures. canadian journal of zoology 88, 170–177. hansen b.b., grøtan v., aanes r., sæther b.-e., stien a., fuglei e., ims r.a., yoccoz n.g. & pedersen å.ø. 2013. climate events synchronize the dynamics of a resident vertebrate community in the high arctic. science 339, 313–315. hansen b.b., isaksen k., benestad r.e., kohler j., pedersen å.ø., loe l.e., coulson s.j., larsen j.o. & varpe ø. 2014. warmer and wetter winters: characteristics and implications of an extreme weather event in the high arctic. environmental research letters 9, article no. 114021, doi: 10.1088/1748-9326/9/11/114021. høye t.t., post e., meltofte h., schmidt n.m. & forchhammer m.c. 2007. rapid advancement of spring in the high arctic. current biology 17, r449–r451. ims r.a., alsos i.g., fuglei e., pedersen å.ø. & yoccoz n. g. 2014. an assessment of mosj — the state of the terrestrial environment in svalbard. report series 144. tromsø: norwegian polar institute. johnson c.j., parker k.l. & heard d.c. 2000. feeding site selection by woodland caribou in north–central british columbia. rangifer special issue 12, 159–172. 10 l. t. beumer et al. https://doi.org/10.1111/gcb.13435 https://doi.org/10.1029/2007wr005929 https://doi.org/10.1029/2007wr005929 https://doi.org/10.3402/polar.v31i0.17258 https://doi.org/10.3402/polar.v31i0.17258 https://doi.org/10.1088/1748-9326/9/11/114021 johnson c.j., parker k.l. & heard d.c. 2001. foraging across a variable landscape: behavioural decisions made by woodland caribou at multiple spatial scales. oecologia 127, 590–602. jónsdóttir i.s. 2005. terrestrial ecosystems on svalbard: heterogeneity, complexity and fragility from an arctic island perspective. biology and environment: proceedings of the royal irish academy 105b, 155–165. koenigk t., berg p. & döscher r. 2015. arctic climate change in an ensemble of regional cordex simulations. polar research 34, article no. 24603, doi: 10.3402/polar.v34.24603. kohler j. & aanes r. 2004. effect of winter snow and ground-icing on a svalbard reindeer population: results of a simple snowpack model. arctic, antarctic, and alpine research 36, 333–341. kumpula j. & colpaert a. 2003. effects of weather and snow conditions on reproduction and survival of semidomesticated reindeer (rangifer t. tarandus). polar research 22, 225–233. laperriere a.j. & lent p.c. 1977. caribou feeding sites in relation to snow characteristics in northeastern alaska. arctic 30, 101–108. leslie jr d.m. & starkey e.e. 1985. fecal indices to dietary quality of cervids in old-growth forests. the journal of wildlife management 49, 142–146. loe l.e., hansen b.b., stien a., albon s.d., bischof r., carlsson a., irvine r.j., meland m., rivrud i.m., ropstad e., veiberg v. & mysterud a. 2016. behavioral buffering of extreme weather events in a high-arctic herbivore. ecosphere 7, article e01374, doi: 10.1002/ ecs2.1374. lundmark c. & ball j.p. 2008. living in snowy environments: quantifying the influence of snow on moose behaviour. arctic, antarctic and alpine research 40, 111–118. macarthur r.h. & pianka e.r. 1966. on optimal use of a patchy environment. the american naturalist 100, 603–609. miller f.l. & barry s.j. 2009. long-term control of peary caribou numbers by unpredictable, exceptionally severe snow or ice conditions in a non-equilibrium grazing system. arctic 62, 175–189. moritz r.e., bitz c.m. & steig e.j. 2002. dynamics of recent climate change in the arctic. science 297, 1497– 1502. nellemann c. 1996. terrain selection by reindeer in late winter in central norway. arctic 49, 339–347. nellemann c. 1998. habitat use by muskoxen (ovibos moschatus) in winter in an alpine environment. canadian journal of zoology 76, 110–116. parker g.a., thomas d.c., madore p.l. & gray d.r. 1975. crashes of muskox and peary caribou populations in 1973-74 in the perry islands, arctic canada. canadian wildlife series progress notes 56, 1–10. parker k.l. 2003. advances in the nutritional ecology of cervids at different scales. ecoscience 10, 395–411. parker k.l., barboza p.s. & gillingham m.p. 2009. nutrition integrates environmental responses of ungulates. functional ecology 23, 57–69. parker k.l., white r.g., gillingham m.p. & holleman d.f. 1990. comparison of energy metabolism in relation to daily activity and milk consumption by caribou and muskox neonates? canadian journal of zoology 68, 106–114. piechura j., beszczyńska-möller a. & osiński r. 2001. volume, heat and salt transport by the west spitsbergen current. polar research 20, 233–240. post e. & forchhammer m.c. 2008. climate change reduces reproductive success of an arctic herbivore through trophic mismatch. philosophical transactions of the royal society b: biological sciences 363, 2367– 2373. pruitt jr w.o. 1959. snow as factor in the winter ecology of barren ground caribou. arctic 12, 159–179. r core team 2013. r: a language and environment for statistical computing. vienna: r foundation for statistical computing. råstad e.b. 2010. effects of spatiotemporal variation in food quality and quantity on ungulate resource selection. master’s thesis, university of tromsø. reimers e. 1980. activity pattern: the major determinant for growth and fattening in rangifer? in e. reimers et al. (eds.): proceedings of the second international reindeer/ caribou symposium, 17–21 september 1979, røros, norway. pp. 466–474. trondheim: directorate for wildlife and freshwater fish. reimers e. 1983. mortality in svalbard reindeer. holarctic ecology 6, 141–149. rennert k.j., roe g., putkonen j. & bitz c.m. 2009. soil thermal and ecological impacts of rain on snow events in the circumpolar arctic. journal of climate 22, 2302–2315. rønning o. 1996. the flora of svalbard. oslo: norwegian polar institute. sæther b.-e. 1997. environmental stochasticity and population dynamics of large herbivores: a search for mechanisms. trends in ecology & evolution 12, 143–149. sæther b.-e. & andersen r. 1990. resource limitation in a generalist herbivore, the moose alces alces: ecological constraints on behavioural decisions. canadian journal of zoology 68, 993–999. serreze m.c., crawford a.d. & barrett a.p. 2015. extreme daily precipitation events at spitsbergen, an arctic island. international journal of climatology 35, 4574–4588. skogland t. 1978. characteristics of the snow cover and its relationship to wild mountain reindeer (rangifer tarandus tarandus l.) feeding strategies. arctic and alpine research 10, 569–580. skogland t. 1984. wild reindeer foraging-niche organization. holarctic ecology 7, 345–379. solberg e.j., jordhøy p., strand o., aanes r., loison a., sæther b.-e. & linnell j.d.c. 2001. effects of densitydependence and climate on the dynamics of a svalbard reindeer population. ecography 24, 441–451. staaland h., brattbakk i., ekern k. & kildemo k. 1983. chemical composition of reindeer forage plants in svalbard and norway. holarctic ecology 6, 109–122. staaland h., scheie j.o., grøndahl f.a., persen e., leifseth a.b. & holand ø. 1993. the introduction of reindeer to brøggerhalvøya, svalbard: grazing preference and effect on vegetation. rangifer 13, 15–19. stephens d.w. & krebs j.r. 1986. foraging theory. princeton: princeton university press. stien a., ims r.a., albon s.d., fuglei e., irvine r.j., ropstad e., halvorsen o., langvatn r., loe l.e., veiberg v. & yoccoz n.g. 2012. congruent responses to weather variability in high arctic herbivores. biology letters 8, 1002–1005. polar research 11 https://doi.org/10.3402/polar.v34.24603 https://doi.org/10.1002/ecs2.1374 https://doi.org/10.1002/ecs2.1374 stocker t.f., qin d., plattner g.-k., tignor m., allen s.k., boschung j., nauels a., xia y., bex v. & midgley p.m. (eds.). 2013. climate change 2013. the physical science basis. contribution of working group i to the fifth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. tveraa t., stien a., bårdsen b.-j. & fauchald p. 2013. population densities, vegetation green-up, and plant productivity: impacts on reproductive success and juvenile body mass in reindeer. plos one 8, e56450, doi: 10.1371/journal.pone.0056450. tyler n.j.c. 1986. the relationship between the fat content of svalbard reindeer in autumn and their death from starvation in winter. rangifer special issue 1, 311–314. tyler n.j.c. 1987. body composition and energy balance of pregnant and non-pregnant svalbard reindeer during winter. symposium of the zoological society of london 57, 203–229. tyler n.j.c. 2010. climate, snow, ice, crashes, and declines in populations of reindeer and caribou (rangifer tarandus l.). ecological monographs 80, 197–219. tyler n.j.c. & øritsland n.a. 1989. why don’t svalbard reindeer migrate? holarctic ecology 12, 369–376. van der wal r., madan n., van lieshout s., dormann c., langvatn r. & albon s.d. 2000. trading forage quality for quantity? plant phenology and patch choice by svalbard reindeer. oecologia 123, 108–115. vivås h.j. & sæther b.-e. 1987. interactions between a generalist herbivore, the moose alces alces, and its food resources: an experimental study of winter foraging behaviour in relation to browse availability. the journal of animal ecology 56, 509–520. westoby m. 1974. an analysis of diet selection by large generalist herbivores. the american naturalist 108, 290–304. 12 l. t. beumer et al. https://doi.org/10.1371/journal.pone.0056450 abstract material and methods study area study species data collection data analyses results discussion acknowledgements disclosure statement funding references editor: sigmund spjelkavik proceedings of the second circumpolar symposium on remote sensing of arctic environments, tromsa, 4-6 may, 1992 remote sensing of polar environments has received increased attention and interest in the last years. the role of the arctic and the antarctic in the global circulation system of air and water masses, the sensitive and fragile ecosystems that meet serious threats from pollution and other human impacts, and the huge amount of information about the past changing climates stored in the vast ice sheets and glaciers call for international management and monitoring programs. remote sensing from satellites is the only realistic way to collect regular information of the environments from the devastated, mostly unpopulated and hostile, areas around the poles. today’s satellites with polar orbits and tomorrow’s polar platforms increase the importance of satellite remote sensing of these parts of the earth. new technology makes it possible to assess the polar regions even through the polar nights. the second circumpolar symposium on remote sensing of arctic environments held in troms~i in may 1992 focused on remote sensing applications in the arctic and antarctic, with special emphasis on environmental monitoring and resource mapping. it followed the first and successful symposium held in yellowknife, canada, in 1990. t h o r b j ~ r n berntsen, the norwegian minister of the environment, opened the symposium in t r o m s ~ where more than 110 scientists from the united states, canada, great britain, italy, estonia, russia, switzerland, france, denmark, sweden, finland and norway attended. the symposium was organized by the university of t r o m s ~ , t r o m s ~ satellite station, akvaplan-niva a/s and the foundation of applied research at the university of t r o m s ~ with financial support from the norwegian polar institute, the county of troms, the ministry of the environment and the ministry of education and research. this special issue of polar research, with selected papers from the symposium in t r o m s ~ , has become possible in cooperation with the norwegian polar institute. we are grateful to mary berge for her work with the manuscripts, to the referees and to the authors. without their help, this issue would not have materialized. grateful thanks are extended to the referees and the authors who contributed to this publication and to the speakers and the other participants who made the symposium an accomplishment. finally, we wish t o thank director frits jensen of the roald amundsen centre for arctic research at the university of tromsb, and the secretary, lillian j ~ r g e n s e n , who were responsible for the makeup of the supporting staff and the administration of the symposium. 6 april 1994 sigmund spjelkavik university of t r o m s ~ por_013.fm polar research 26 2007 209 © 2007 the author 209 b o o k r e v i e w review of jenter på langs—på ski over svalbard , by kristin folsland olsen, vera simonsson & ingebjorg tollefsen (2006). oslo: fri flyt as. 119 pp. isbn 978-8299643245. at first sight i thought this book was going to turn out to be just another account of a personal skiing trip in the arctic, of which there have been many in recent years. however, because i live in svalbard and have participated in several ski expeditions (the last one traversed greenland and was led by a disabled woman who accomplished the journey by sit-ski) i am always interested in reading other people’s experiences of polar expeditions, as they may provide inspiration for a future trip or kindle new dreams. i’m also keen to learn from other people’s mistakes and successes, as well as from their choice of equipment and experiences in its use. the title can be translated as something like “girls on tour—by ski across svalbard”. (in the phrase jenter på langs , jenter means “girls” and på langs means “lengthwise”, which refers to the south–north axis of their traverse.) the book is about three students—one swedish and two norwegian—training to be outdoor guides in svalbard, who dreamed about wrapping up their stay in longyearbyen with a long skiing trip. this was the beginning of their idea of traversing svalbard from south to north on skis. the trip started from sørkapp, the southernmost point of spitsbergen, and followed a winding route over glaciers, mountain passes and frozen fjords before reaching verlegenhuken, the most northern point of the island, and covered a distance of 550 km. the book caught and held my attention more than i had anticipated it would. the expedition is described with humour and, compared with most expedition accounts, in an unconventional way. the book makes light reading and is an interesting, well-balanced mix of narrative description, fact boxes and excerpts from the girls’ diaries, interspersed with a number of good photographs. it covers most aspects of a successful expedition, from planning the logistics, pre-expedition concerns about the equipment, the physical conditions they were confronted with, and so on. the fact boxes touch on almost all the aspects of expedition life the reader could want to know about when planning a similar or shorter expedition in svalbard, and are a good starting point for finding out more on the different topics. information in the fact boxes covers food rations, safety equipment, polar bears, glaciers, svalbard weather, and flora and fauna. there is also a fairly comprehensive equipment list, and maps with the authors’ route and camp positions marked. excerpts from the diaries of the participants add insights from each member regarding how she experienced the trip, as well as her relationship with the other team members. the diary texts switch between norwegian and swedish, which is a bit irritating at times, but it does lend a more personal touch to the book. conflicts and problems encountered during the expedition are also touched upon from all three perspectives. personal tensions often arise on such expeditions as a result of the participants’ varying backgrounds, motivations and expectations, but they are often left out of such literature. it was therefore refreshing to read diary excerpts that dealt with how frustrations and conflicts developed, and how they were either confronted or ignored. the authors have struck a good balance between describing the challenges they faced during this tough trip and how they got on with the tasks at hand, such as enduring long periods of bad weather, poor visibility and encounters with polar bears, without exaggerating the hardships as many other expedition books tend to do. i found the book an enjoyable account of three young women following their dream. by careful planning and attention to detail, and a bit of luck, they were successful in what was a very difficult and demanding journey. this book should appeal to anyone with a spirit of adventure for the arctic, and readers planning a similar adventure will find a great deal of useful information. correspondence harvey goodwin norwegian polar institute, polar environmental centre, no-9296 tromsø, norway. e-mail: goodwin@npolar.no por_035.fm 96 polar research 26 2007 96 – 103 © 2007 the author f r o m t h e c o n f e r e n c e m e lt i n g i c e — a h o t to p i c ? climate change and biodiversity in the arctic—nordic perspectives philip a. wookey school of biological and environmental sciences, university of stirling, stirling, fk9 4la, uk. e-mail: philip.wookey@stir.ac.uk this paper is based upon a presentation given on united nations environment programme (unep) world environment day, 5 june 2007, as part of the nordic perspectives session of the climate change conference melting ice—a hot topic? the broad aims of this paper are to define biodiversity and ecosystem services, to set the biodiversity of the arctic terrestrial realm into its global context, and, through the use of case studies, to illustrate how environmental change can influence biodiversity and ecosystems, and to explore what the implications of these changes might be. a comprehensive treatment of the topic is well beyond the scope of both the presentation and this paper, but the reader is directed to the caff (2001) and acia (2005) reports for reviews and synthesis. biodiversity and ecosystem services biodiversity is defined as the variability among living organisms from all sources including, inter alia , terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part; this includes diversity within species, between species and of ecosystems. (article 2, convention on biological diversity 1992) this presentation focuses upon terrestrial biodiversity, but a key point to emphasize in the definition is that biodiversity includes “diversity within species” and “of ecosystems”. so biodiversity cannot be used interchangeably with “species richness” (numbers of species). in the arctic the diversity within species can be very great, and caff (2001: 49) notes that “genetic, morphological and behavioural diversity may be especially significant components of biodiversity”; this assumes even greater significance in the arctic, where species richness is often low compared with communities and ecosystems from temperate and tropical environments. biodiversity is fundamental to the provision of “ecosystem services”, and these are defined by the food and agriculture organization (fao) as the conditions and processes through which natural ecosystems, and the species that make them up, sustain and fulfil human life. examples include provision of clean water, maintenance of liveable climates (carbon sequestration), pollination of crops and native vegetation, and fulfilment of people’s cultural, spiritual, intellectual needs. (fao 2005) note that the term “ecosystem services” is anthropocentric, and refers to services to humankind. so, in essence, when we talk of ecosystem services this is a utilitarian view of life on earth, but it does provide a basic foundation for an assessment of the value of biodiversity to people, and as such has some worth. in the context of the arctic terrestrial realm, ecosystem services that are straightforward to recognize include (i) the provision of food and fodder (e.g., for reindeer herders and their animals in the nordic and russian contexts), (ii) fuel and fibre (the latter including animal and plant products), (iii) a sense of cultural and spiritual identity, (iv) the maintenance of fundamental ecosystem services (such as photosynthesis, decomposition and nutrient recycling), (v) a clear link to the global climate system and biogeochemical cycles, (vi) the provision of genetic resources and (vii) a clear link with service industries such as the tourism sector. in relation to (v), the arctic is profoundly important in the global energy budget (with snow cover, and the forest– tundra ecotone, assuming great importance in terms of albedo and surface roughness effects). in terms of genetic resources (vi), cold-adapted organisms (particularly micro-organisms) are likely to have major potential for development of therapeutic or pharmaceutical products, and soils and sediments undoubtedly represent major reservoirs of genetic diversity in the arctic terrestrial realm (as indicated by the work of torsvik et al. 2002). doi:10.1111/j.1751-8369.2007.00035.x p. a. wookey climate change and biodiversity in the arctic polar research 26 2007 96 – 103 © 2007 the author 97 arctic terrestrial biodiversity in context set against this background of the role of biodiversity for ecosystem services in the arctic, and emphasizing the point that biodiversity includes within-species and among-ecosystem diversity, a tacit generalization can be made that biodiversity is low in the arctic (at least among higher plants and vertebrates: see table 1). the results of rannie (1986), chernov (1989, 1995) and matveyeva & chernov (2000) show a clear inverse relationship, for example, between mean july temperature and the biodiversity of vascular plant species, nesting birds, ground beetles and day butterflies across transects in canada and russia. the logical conclusion from this is that warming should increase biodiversity (at least in the long term). but this is likely to be a gross oversimplification, particularly bearing in mind the predicted rapid rates of climate change (especially for the arctic landmasses), and the other drivers of change superimposed upon climate; this is an issue that will be raised again in due course. some specialist “arctic” species may, however, be lost (e.g., of the plants, some “euarctic” components, currently widespread in the northern part of the arctic tundra zone, and hyperarctic species of the northern tundra, polar deserts and semi-deserts, may be especially vulnerable; see callaghan et al. 2005). this partly reflects the likely northern shift in life zones, and an overall contraction of the tundra biome. plants, animals and microorganisms are also likely to respond differentially to change (because of contrasting life histories, generation times and dispersal mechanisms), resulting in the advent of “novel” communities for which there are no contemporary analogues. although interspecific diversity is generally low in the arctic, some taxa are proportionally well-represented in the arctic terrestrial biota (table 1), in particular in the cryptogams (spore-producing plants; specifically the algae, lichens and mosses) and soil invertebrates such as the collembola (springtails) (caff 2001; acia 2005). the diversity of soil microorganisms in norwegian tundra and arctic desert (svalbard) soils also compares favourably with arable and pasture soils (torsvik et al. 2002). indeed for arctic terrestrial ecosystems the soil is undoubtedly the largest reservoir of biodiversity and genetic capital, although this situation is unlikely to be unique among terrestrial ecosystems. soil biodiversity is, in ecosystem terms, as important as plant biodiversity, and in terms of energy flows and material recycling there are internal recycling processes (where fig. 1 a general model of a terrestrial ecosystem. the three component subsystems (plant, herbivore and decomposer) are shown, together with their component parts. the major transfers of material are denoted by arrows, whereas organic matter pools are shown within rectangles, and inorganic pools are shown within “clouds”. note, in particular, that a key raw material for photosynthesis (carbon dioxide [co 2 ]) is returned to the atmosphere principally by the decomposer organisms (this is certainly the case in the arctic), and that “mineral” nutrients are also made available to plants by the decomposers (although there is growing evidence that plants may “bypass” this process and take up amino acids, for example, directly from the soil, or via mycorrhizas). note, also, the internal recycling within the decomposition subsystem: this is an aspect of internal biocomplexity that is not matched directly within the plant and herbivore subsystems. furthermore, we know very little indeed of soil biodiversity in most arctic terrestrial ecosystems, in spite of the significance of the decomposition subsystem to ecosystem processes and properties (including carbon sequestration in soil organic matter and permafrost). figure redrawn from swift et al. (1979). carnivore 2carnivore 1herbivore detritus decomposers co2 inorganic nutrients plant subsystem herbivore subsystem decomposition subsystem recycling table 1 biodiversity estimates in terms of species richness (numbers of species) within selected groups for the arctic terrestrial realm north of the latitudinal treeline, and their percentage of the terrestrial total globally. modified from caff (2001) and acia (2005). “other groups” includes amphibians and reptiles (seven species), centipedes (10 species), terrestrial molluscs (three species), oligochaetes (earthworms and enchytraeid worms; 70 species) and nematodes (ca. 500 species). group arctic species numbers arctic % of total insects 3300 0.4 mites 700 1.9 springtails 400 6.0 spiders 300 1.7 birds 240 2.9 mammals 75 1.7 other groups 600 – fungi 2500 2.3 lichens 2000 11.0 flowering plants 1735 0.7 algae 1200 3.3 mosses 600 4.1 liverworts 250 2.5 ferns 62 0.6 conifers 12 1.6 98 polar research 26 2007 96 – 103 © 2007 the author climate change and biodiversity in the arctic p. a. wookey fig. 2 schematic diagram of the annual pattern of environmental variables and net photosynthesis at barrow, alaska. barrow has a climate classified as just within the high arctic zone. the period of net photosynthesis is highlighted by the dashed box. notice how snow cover lasts through until june, at a time when solar radiation inputs are at a peak and are soon to decline. earlier snowmelt is likely to increase phytomass and accelerate plant reproductive phenology. later senescence may result from later autumn freeze-up, although light may be limiting, and senescence may be triggered by changes in light quality (from chapin and shaver, 1985 reprinted with permission from kluwer academic publishers and from the author.) fig. 3 a schematic diagram showing a mesotopographic gradient for the arctic that includes five habitats: dry, mesic (zonal), wetland, snowbed and streamside vegetation. the landscape heterogeneity here, associated with the presence of a snowbed, increases habitat diversity and thus biodiversity. asynchronous melting of snowbeds through the thaw period maintains the availability of newly-emerged high-quality food for herbivores over space and time. earlier thawing of snowbeds has the potential to reduce habitat diversity. redrawn from walker (2000). 2 2 1 4a 3 4b 55 late-melting snow drift prevailing wind 1. dry exposed ridges 2. mesic zonal sites 3. wet meadows 4. snowbeds a. well-drained, early -melting b. poorly -drained, late -melting 5. streamside sites decomposer organisms themselves die, and are decomposed in turn by others) which confer a complexity to the decomposer subsystem that is frequently overlooked in discussions of biodiversity and environmental change (fig. 1). environmental change in the arctic is multifaceted environmental change in the arctic is multifaceted, and organisms respond both directly and indirectly to these changes. climate change is just one of several environmental change “drivers”, alongside the ongoing changes in atmospheric composition themselves (e.g., increasing co 2 concentrations; increasing deposition of airborne nand s-containing contaminants; and stratospheric ozone depletion resulting in greater uvb fluxes at the surface), and direct anthropogenic disturbance (e.g., for transport infrastructure, fossil fuel and mineral extraction, forestry, tourism and hydropower generation). because environmental changes of contrasting rate, magnitude and geographical extent are all occurring simultaneously in the arctic, and organisms will respond differentially to these changes, there are serious challenges involved in attempting to predict how biodiversity, communities and ecosystems will respond to change. and we cannot always rely with confidence on the lessons of history (“the past as a key to the future”; see adams & woodward 1992) because changes are occurring for which there are no analogues in the palaeoenvironmental or palaeoecological records. p. a. wookey climate change and biodiversity in the arctic polar research 26 2007 96 – 103 © 2007 the author 99 but what are the effects of warming? however, setting this issue aside, even in the case of climate warming it is by no means straightforward to predict the impacts on terrestrial ecosystems. in an arctic context, landscape heterogeneity and the role of the cryosphere are potentially significant “modifiers” of the effects of warming on ecosystems. figure 2, for example, shows the potential for earlier snowmelt in tundra regions to have a major impact on plant phenology and photosynthesis resulting from the availability of substantial fluxes of photosynthetically active radiation (par) around the summer solstice (when solar elevations are high). later autumn freeze-up may also result in delayed plant senescence. but earlier snowmelt may also have negative, or counterintuitive, consequences. in complex landscapes, where snow is redistributed from wind-exposed areas to hollows and depressions, early snowmelt may cause a reduction of habitat heterogeneity caused by the loss of snowbeds. snowbed “specialists” (e.g., the moss kiaeria starkei ) may not be able to survive the change in physical environmental conditions, or increased competition. furthermore, earlier melting of snowbeds may also have negative consequences for herbivores if it means that the availability of high-quality forage (associated with new growth) is temporally “compressed” earlier into the summer; in this respect, complex landscapes, with a mosaic of vegetation communities and late-melting snowbeds, might offer newly-emerged high-quality food for herbivores throughout a growing season (fig. 3) (björk & molau 2007). the effects of experimental warming on both arctic and alpine tundra ecosystems has been investigated by the team of scientists from itex (the international tundra experiment). this experiment was launched, in concept, in 1990, and soon after was established at 28 sites in the tundra biome. the broad geographical coverage and international participation were seen as important components of the original set-up, in recognition that plants in contrasting parts of their geographical range might respond differently to the same change in temperature (fig. 4). initially, itex focused upon the phenological and growth responses of a set of broadly circumpolar arctic and alpine vascular plant species (see e.g., fig. 5) to experimental warming (achieved by using small hexagonal open-topped chambers [otcs]), designed to simulate the greenhouse effect. the otcs generally produced a near-surface warming of around 1–3 ° c above the ambient temperatures for control (unwarmed) plots. after several years (up to four) of the experiment, the data from 13 of the sites was subjected to meta-analysis to test whether any generalizations could be made regarding geographical contrasts in responses to warming, as well as contrasts relating to plant functional type (e.g., deciduous vs. evergreen dwarf shrubs, forbs and graminoids). this meta-analysis (arft et al. 1999) demonstrated the sensitivity of tundra plants to warming, and identified differential responses among contrasting growth forms and among contrasting regions (high arctic; low arctic; alpine). with regards to the current presentation, however, the subsequent itex work on community (as opposed to individual plant) responses to warming (walker et al. 2006) provides data to suggest that some plant growth forms (specifically lichens and bryophytes) do badly in warmer conditions (figs. 6, 7). this may be the result of shading by plant functional types that respond particularly vigorously to warming (e.g., deciduous dwarf shrubs such as the dwarf birch [ betula nana ]), or to competition for nutrients, or to factors such as surface drying (a possible artefact of the otcs). diversity and evenness indices all decreased significantly with fig. 4 this schematic diagram illustrates the performance of a plant species (in terms of net primary productivity [npp]) across a gradient of temperature (which could be expressed as mean temperatures over a growing season, or as some other metric of thermal energy availability, e.g., growing degree days, or in the case of tundra plants thawing degree days, representing accumulated “thermal time”). increasing temperature in tundra ecosystems will co-vary with other abiotic factors (e.g., precipitation or depth of the active layer) and also with biotic factors, such as intensity of competition or herbivory. intensity of competition (e.g., for light or soil nutrients) is likely to increase from the extreme polar deserts and alpine fellfields to the more closed tundras of the low arctic and midto low alpine (perhaps leading to a skewed npp curve, with values dropping more steeply at the warmer end of the distribution as a result of competition interactions). note that, according to this scheme, a given temperature increase ( ∆ t ) could produce quite different outcomes depending on where in the species’ range the warming occurs. thus, warming at the colder end of the distribution could markedly improve plant performance, whereas towards the warmer end of the distribution increased respiratory demands, or intensity of competition, could reduce npp to the extent that the species dies out, or is forced out, of the community. temperature/position in range p ro ce ss r a te north south npp intensity of competition/ influence of ‘invasive’ species 100 polar research 26 2007 96 – 103 © 2007 the author climate change and biodiversity in the arctic p. a. wookey fig. 5 some of the vascular plant species studied as part of itex (arft et al. 1999; walker et al. 2006). (a) saxifraga oppositifolia (purple saxifrage), (b) silene acaulis (moss campion), (c) dryas octopetala ssp. octopetala (mountain aven) and (d) cassiope tetragona (arctic bell heather). (d) (c) (a) (b) fig. 7 response of tundra plant community variables to experimental warming in itex. the symbols represent the mean effect size based on the meta-statistic “hedges d ” (the normalized difference between experimental and control means adjusted for sample size), and the lines give 95% confidence intervals. the effect sizes for canopy height, ordination scores and diversity indices were all considered “moderate” by meta-analysis convention. note the general increase in height of vascular plants (triangles), the significant increases in shrubs, deciduous shrubs and litter cover, and the decreases in both lichen and bryophyte cover (circles) and diversity indices (diamonds). (from walker et al. 2006; reprinted with permission from the authors, copyright 2006 national academy of sciences, u.s.a.) fig. 6 itex sites contributing to the walker et al. (2006) meta-analysis of plant community responses to experimental warming. (from walker et al. 2006; reprinted with permission from the authors, copyright 2006 national academy of sciences, u.s.a.) p. a. wookey climate change and biodiversity in the arctic polar research 26 2007 96 – 103 © 2007 the author 101 fig. 8 environs of the agricultural research institute research station near akureyri, north iceland, with ice-layer formation in the foreground. damage to perennial grasses resulting from anoxia beneath the ice cover can be very severe during “mild” winters. (photograph by permission of bjarni e. gu leifsson.)ð warming, and the results strongly suggest that biodiversity might decrease (at least in the short term) in response to warming. the other notable results were that tundra plant communities exhibited detectable responses to warming over time periods of only three to four years, and the significant “winners” were the deciduous shrubs, with increases both in percentage cover and in height (fig. 7) (see also sturm, racine & tape (2001). the observation that lichens are adversely affected by experimental manipulations simulating climate change impacts (including the addition of mineral nutrients to simulate more rapid decomposition processes) has also been observed by cornelissen et al. (2001), so this result seems robust and consistent. so, the effects of climate warming on tundra ecosystems are by no means straightforward to predict, and a criticism that has been levelled at programmes such as itex is that it might have placed too much weight on summer warming effects (whereas the general circulation models of the earth’s climate suggest that winter warming will be of much greater magnitude in the polar regions). warmer winters in a cold environment might be expected to be beneficial for the biota, but again there are data from the arctic suggesting the converse. aanes et al. (2000) and yoccoz & imms (1999) have data from svalbard showing that both svalbard reindeer ( rangifer tarandus platyrhynchus ) and sibling voles ( microtus rossiaemeridionalis ) have undergone population crashes during winters with freezing rain. this is likely to result from the formation of ice layers in the snowpack (which reindeer cannot penetrate for foraging), or the collapse of the subnivean space beneath the snowpack. such examples are not restricted to svalbard. indeed in the nordic context, milder winters with increased incidence of freezing and thawing cycles may have serious implications for summer pasture systems with perennial grasses (fig. 8), as well as for natural ecosystems (see, for example, robinson et al. 1998). the arctic is not isolated in contrast to the views of many people living in industrialized regions to the south, the arctic is not isolated neither, biologically, climatically nor socio-economically. migratory animals provide clear examples of the linkages between the arctic and lower latitudes, and strong climatic teleconnections (e.g., between the north atlantic oscillation, arctic oscillation and the el niño–southern oscillation) are evident, as are their biological consequences (e.g., aanes et al. 2002; post & forchhammer 2004; forchhammer et al. 2005). events and policy outside the arctic often have a clear impact within the arctic, even if this was unintentional. the european union fragile project (fragility of arctic goose habitat: impacts of land use, conservation, and elevated temperature) highlights this, as does the example of snow geese in north america. the numbers of several species of goose that breed in svalbard in the summer, but that migrate to western europe to overwinter, have increased dramatically in the last 40 years (with a 30-fold increase in barnacle geese [ branta leucopsis ] and a fourfold increase in pink-footed geese [ anser brachyrhynchus ]). changes in land use and hunting practice in the overwintering areas (both linked with socio-economic and/or political decisions) have resulted in rapid increases in winter survivorship, whereas earlier melt-out in the breeding areas may be responsible for increased breeding success (cooper et al. 2004). research to determine the impacts of the increased grazing intensity and climate change on the vegetation communities and ecosystem processes of the breeding areas in svalbard is ongoing. this interplay between climate change drivers and socio-economic/ political drivers of change demonstrates clearly the linkages between climate, wildlife and society, and these linkages extend across thousands of kilometres. conclusions • the arctic biota has been subject to dramatic environmental change during the last 2.5 million years, but ongoing and predicted change is rapid and very different. • conventional wisdom suggests that biodiversity should increase with warming in the medium to long term, but the tundra biome is increasingly “compressed” between the boreal zone and the arctic ocean. 102 polar research 26 2007 96 – 103 © 2007 the author climate change and biodiversity in the arctic p. a. wookey • many species and habitats in the arctic are potentially highly vulnerable to change. • rates of change are so rapid that “novel” assemblages of organisms will develop, and we know very little of how these will function, or of the possible role of “invasive” species. • like it or not, the arctic and its organisms and communities are set to provide an early detection system of the impacts of environmental change on planet earth. acknowledgements many thanks to the norwegian polar institute, the nordic council of ministers and the united nations environment programme for the opportunity to speak on world environment day. i would also like to thank my colleagues in the international tundra experiment (itex) and the circum-arctic terrestrial biodiversity initiative (cat-b; supported by the international arctic science committee) for their insights, enthusiasm and support over the years. references aanes r., sæther b.-e. & øritsland n.a. 2000. fluctuations of an introduced population of svalbard reindeer: the effects of density dependence and climatic variation. ecography 23 , 437–443. aanes r., sæther b.-e., smith f.m., cooper e.j., wookey p.a. & øritsland n.a. 2002. the arctic oscillation predicts effects of climate change in two trophic levels in a high-arctic ecosystem. ecology letters 5 , 445–453. acia (arctic impact climate assessment) 2005. arctic climate impact assessment—scientific report . cambridge: cambridge university press. adams j.m. & woodward f.i. 1992. the past as a key to the future—the use of paleoenvironmental understanding to predict the effects of man on the biosphere. advances in ecological research 22 , 257–314. arft a.m., walker m.d., gurevitch j., alatalo j.m., bret-harte m.s., dale m., diemer m., gugerli f., henry g.h.r., jones m.h., hollister r.d., jónsdóttir i.s., laine k., lévesque r., marion g.m., molau u., mølgaard p., nordenhäll u., raszhivin v., robinson c.h., starr g., stenström a., stenström m., totland ø., turner p.l., walker l.j., webber p.j., welker j.m. & wookey p.a. 1999. responses of tundra plants to experimental warming: meta-analysis of the international tundra experiment. ecological monographs 69 , 491– 511. björk r.g. & molau u. 2007. ecology of alpine snowbeds and the impact of global change. arctic, antarctic and alpine research 39 , 34–43. caff (conservation of arctic flora and fauna) 2001. arctic flora and fauna: status and conservation . helsinki: edita. callaghan t.v., björn l.o., chapin f.s. iii, chernov y., christensen t.r., huntley b., ims r., johansson m., riedlinger d.j., jonasson s., matveyeva n., oechel w., panikov n. & shaver g. 2005. arctic tundra and polar desert ecosystems. in acia (c. symon et al. [eds.]): arctic climate impact assessment—scientific report . pp 243–352. cambridge: cambridge university press. chapin iii f.s. & shaver g.r. 1985. arctic. in b.f. chabot & h.a. mooney (eds.): physiological ecology of north american plant communities . pp 16–40. new york: chapman and hall. chernov y.i. 1989. heat conditions and arctic biora. ekologiya 2 , 49–57 (in russian). chernov y.i. 1995. diversity of the arctic terrestrial fauna. in f.s. chapin iii & c. körner (eds.). arctic and alpine biodiversity: patterns, causes and ecosystem consequences. ecological studies 113 , 81–95. convention on biological diversity 1992. accessed on the internet at http://www.cbd.int/convention/convention. shtml on 25 june 2007. cooper e., jónsdóttir i.s., chaput d., kuijper d., loonen m., pahud a., sjögersten s., ubels r., van der wal r., woodin s. & huiskes a. 2004. climate change and goose grazing on svalbard’s tundra. acia international symposium on climate change in the arctic. 9–12 november, reykjavik, iceland. cornelissen j.h.c., callaghan t.v., alatalo j.m., michelsen a., graglia e., hartley a.e., hik d.s., hobbie s.e., press m.c., robinson c.h., henry g.h.r., shaver g.r., phoenix g.k., jones d.g., jonasson s., chapin f.s., molau u., neill c., lee j.a., melillo j.m., sveinbjörnsson b. & aerts r. 2001. global change and arctic ecosystems: is lichen decline a function of increases in vascular plant biomass? journal of ecology 89 , 984–994. fao (food and agriculture organization) 2005. ecosystem services. accessed on the internet at http://www.fao.org/ag/ wfe2005/glossary_en.htm on 25 june 2007. forchhammer m.c., post e., berg t.b.g., hoye t.t. & schmidt n.m. 2005. local-scale and short-term herbivore–plant spatial dynamics reflect influences of large-scale climate. ecology 86 , 2644–2651. matveyeva n. & chernov y. 2000. biodiversity of terrestrial ecosystems. in m. nutall & t.v. callaghan (eds.): the arctic: environment, people, policy . pp 233–274. hardwood academic publishers. post e. & forchhammer m.c. 2004. spatial synchrony of local populations has increased in association with the recent northern hemisphere climate trend. proceedings of the national academy of sciences (pnas) 101 , 9286–9290. rannie w.f. 1986. summer air-temperature and number of vascular species in arctic canada. arctic 39 , 133–137. robinson c.h., wookey p.a., lee j.a., callaghan t.v. & press m.c. 1998. plant community responses to simulated environmental change at a high arctic polar semi-desert. ecology 79 , 856–866. sturm m., racine c. & tape k. 2001. increasing shrub abundance in the arctic. nature 411 , 546–547. http://www.cbd.int/convention/convention http://www.fao.org/ag/ p. a. wookey climate change and biodiversity in the arctic polar research 26 2007 96 – 103 © 2007 the author 103 swift m.j., heal o.w. & anderson j.m. 1979. decomposition in terrestrial ecosystems . oxford: blackwell scientific publications. torsvik v.l., øvreås l. & frede thingstad t. 2002. prokaryotic diversity—magnitude, dynamics and controlling factors. science 296 , 1064–1066. walker d.a. 2000. hierarchical subdivision of arctic tundra based on vegetation response to climate, parent material and topography. global change biology 6 , 19–34. walker m.d., wahren c.h., hollister r.d., henry g.h.r., ahlquist l.e., alatalo j.m., bret-harte m.s., calef m.p., callaghan t.v., carroll a.b., epstein h.e., jónsdóttir i.s., klein j.a., magnússon b., molau u., oberbauer s.f., rewa s.p., robinson c.h., shaver g.r., suding k.n., thompson c.c., tolvanen a., totland ø., turner p.l., tweedie c.e., webber p.j. & wookey p.a. 2006. plant community responses to experimental warming across the tundra biome. proceedings of the national academy of sciences (pnas) 103 , 1342–1346. yoccoz n.g. & imms r.a. 1999. demography of small mammals in cold regions: the importance of environmental variability. in a. hofgaard et al. (eds.): animal responses to global change in the north . ecological bulletin 47 , 137–144. doi:10.3402/polar.v35.29364 r e s e a r c h n o t e parasites of the antarctic toothfish (dissostichus mawsoni norman, 1937) (perciformes, nototheniidae) in the pacific sector of the antarctic ilya i. gordeev1 & sergey g. sokolov2 1 laboratory of ecology and bioresources of the arctic and antarctic, russian federal research institute of fisheries and oceanography, 17, v. krasnoselskaya st.,107140 moscow, russia 2 laboratory of fauna and ecology of parasites, center of parasitology, a.n. severtsov institute of ecology and evolution, russian academy of sciences, 33, leninsky pr.,119071 moscow, russia keywords toothfish; parasites; antarctic fisheries; ccamlr; infection; southern ocean. correspondence ilya i. gordeev, laboratory of ecology and bioresources of the arctic and antarctic, russian federal research institute of fisheries and oceanography, 17, v. krasnoselskaya st., 107140 moscow, russia. e-mail: gordeev_ilya@bk.ru abstract the antarctic toothfish (dissostichus mawsoni norman, 1937) is one of the main target species of commercial fisheries in the antarctic. it is an endemic and is found along the shelf of antarctica, as well as on the slopes of seamounts, underwater elevations and islands in the sub-antarctic. it feeds on a variety of fish and cephalopods and can be an intermediate/paratenic host of some helminthes, whose final hosts are whales, seals, large rays and sharks. this article presents new data on toothfish infection in the pacific sector of the antarctic. specimens were examined during commercial longline fishing in the ross sea and the amundsen sea in january�february 2013. fourteen species of parasites were found using standard parasitological methods and genetic analysis. the antarctic toothfish (dissostichus mawsoni norman, 1937) is one of two species in the genus and one of the main target species of commercial fisheries in the antarctic. dissostichus mawsoni is endemic, with a circumpolar distribution along the shelf of antarctica and on the slopes of seamounts, underwater elevations and islands in the sub-antarctic (shust & petrov 2009). the history of targeted research on the antarctic toothfish and subsequent exploratory fishing began in 1969 (calhaem & christoffel 1969), but its life cycle and biology are still poorly understood because its habitat is covered by sea ice from march to december (juhov 1982; andrijašev 1986; dewitt in gon & heemstra 1990; shust et al. 2005; hanchet 2006). the study of antarctic toothfish parasites includes a few studies carried out mainly in the atlantic sector of the southern ocean. sixteen species of helminthes were found near the antarctic peninsula (e.g., rodjuk 1984; gaevskaja et al. 1990; zdzitowiecki 1990, 1991a; rocka 2003, 2004; rokicki et al. 2009). three species of trematodes were found in the ross sea (holloway & bier 1968; sokolov & gordeev 2013, 2015) as well as the copepod eubrachiella antarctica quidor, 1906 (smith et al. 2006). two species of monogenea were recorded in the pacific sector of the subantarctic (gaevskaja et al. 1990) and in the antarctic (oguz et al. 2012). material and methods a total of 20 adult specimens of dissostichus mawsoni (total length 97�159 cm; weight 11.23�55.04 kg) were caught between 21 and 27 january 2013 in the central part of the ross sea. five specimens were caught on 3 february 2013 in the amundsen sea from the fishing vessel yantar35 when fishing for toothfish at depths ranging from 865 to 1425 m using mustad autoline bottom longline fishing gear inside the convention for the conservation of marine living resources area. all specimens were caught on the continental slope between 75825? s, 174842? w and 69844? s, 126846? w. straight after capture all specimens were examined macroscopically for the presence of polar research 2016. # 2016 i.i gordeev & s.g sokolov. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 29364, http://dx.doi.org/10.3402/polar.v35.29364 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/29364 http://dx.doi.org/10.3402/polar.v35.29364 ectoparasites and then dissected and studied for helminthes and other metazoan parasites using a standard method of parasitological examination (byhovskajapavlovskaja 1985). prefixation treatment of trematodes, cestodes and monogeneas included cleaning and straightening with the compression method for better identification. acanthocephala were transferred to freshwater until the proboscis everted prior to fixation. all parasites except nematodes were preserved in 70% and 96% ethanol. nematodes were preserved in 4% formaldehyde and three days later transferred to 70% ethanol for longterm storage. some nematodes were preserved in 96% ethanol. digenea were stained with acetic carmin, dehydrated, contrasted (cleared) with dimethyl phthalate or diethyl phthalate, and finally mounted in canada balsam. cestoda were hydrated, stained with harris’s hematoxylin, differentiated in tap water, de-stained in ethanol, dehydrated, cleaned in methyl salicylate, and finally mounted in canada balsam (jensen et al. 2011). fish species were identified with reference to gon & heemstra (1990). parasites were identified with the aid of literature, including holloway & bier (1968), zdzitowiecki (1991b), rocka & zdzitowiecki (1998), zdzitowiecki (1999), rocka (2003), smith et al. (2006) and bray et al. (2008). tetraphyllidean and onchoproteocephalidean larvae were identified using dna sequencing. dna extraction was carried out using the standard saline method (aljanabi & martinez 1997). amplifications were performed in a final reactions volume of 12.5 ml: 1.5 ml pcr buffer (sileks, russia); 2.5 mm mgcl2; 0.6 mm dntp; 2 pmol of each primer; 200 ng dnamatrix; and 1 unit of taq-polymerase (sileks, moscow) with the following cycle protocol: a preliminary denaturation of dna at 948c for two minutes was followed by the syntheses of dna products: melting at 948c for 30 s, annealing the primers at 558c for 45 s, and dna syntheses at 728c for two minutes. a final extension cycle of five minutes at 728c followed. amplification of lsudna was performed using primers 1200r (5?� gcatagttcaccatctttcgg�3?) (lockyer et al. 2003) and lsu5 5?�taggtcgacccgctgaayttaagca�3?) (littlewood et al. 2000). sequencing was carried out with bigdye version 1.1 on the automatic sequencer abi 3100. results processing and multiple alignment were carried out using the software package dnastar (lasergene inc.). results a total of 14 parasite taxa were detected (table 1). the copepod eubrachiella antarctica was found on and near the dorsal, pectoral and anal fins. the monogenean pseudobenedenia dissostichi timofeeva, gaevskaja & kovaliova, 1987 was found mainly between the pectoral fins, but sometimes on the rest of the body surface, except the head. other species not listed in table 1*leeches (hirudinea) moorebdellina sp. and pleurobdella sp.*were very common on dissostichus mawsoni, but infection indices of these species are not available because of the lengthy contact between examined specimens in the fish-receiving. two morphological types of plerocercoid were found: small (1�2 mm) with bilocular bothridia, and large (2�4 mm) with trilocular bothridia. sequences of small plerocercoids with bilocular bothridia exhibited a 95% match with calyptrobothrium sp. (genbank no. af382087.1) collected by brickle et al. (2001) from apristurus laurussonii (saemundsson, 1922) (formerly accepted as apristurus atlanticus koefoed, 1932) caught in the north sea. large plerocercoids with trilocular bothridia showed 99% match with onchobothrium antarcticum wojciechowska, 1990 (genbank no. kf882021.1) collected by laskowski & rocka (2014) from notothenia rossii ricardson, 1844 which were caught around the south shetland islands. discussion in comparison with other high-level predators from the near-continental areas of the ocean, data on the parasites of dissostichus mawsoni are fragmentary and scarce. only seven of the 14 species found in our study were previously recorded as parasites of d. mawsoni: neolepidapedon trematomi prudhoe & bray, 1973, helicometra antarcticae holloway & bier, 1968, onchobothrium antarcticum, e. antarctica, hysterothylacium sp., echinorhynchus petrotschenkoi (rodjuk 1984) and corynosoma bullosum linstow, 1892. neolepidapedon trematomi and corynosoma bullosum linstow, 1892 were found by zdzitowiecki (1987 1988, 1990, 1999) in the south shetland islands area and the first of the above-mentioned species by sokolov & gordeev (2013), sokolov & gordeev (2015) in the ross sea. helicometra antarcticae was described by holloway & bier (1968) from samples taken from d. mawsoni caught in mcmurdo sound (ross sea), and we later found specimens in the open waters of the pacific sector and in the ross sea (sokolov & gordeev 2013, 2015). eubrachiella antarctica on the trunks of d. mawsoni in the ross sea was considered to be a marker or biological tag to aid stock discrimination (smith et al. 2006). the plerocercoid o. antarcticum and the nematode hysterothylacium sp. were recorded living on this species in admiralty bay and the open sea shelf near the south shetlands islands (rocka 2003, 2004, respectively). metechinorhynchus petrotschenkoi*later accepted as parasites of the antarctic toothfish i.i gordeev & s.g sokolov 2 (page number not for citation purpose) citation: polar research 2016, 35, 29364, http://dx.doi.org/10.3402/polar.v35.29364 http://www.polarresearch.net/index.php/polar/article/view/29364 http://dx.doi.org/10.3402/polar.v35.29364 e. petrotschenkoi*was found in the south shetland islands area (rodjuk 1984). contracoecum sp., proctophantastes gillissi (overstreet & pritchard, 1977) bray & gibson, 1986, p. dissostichi, diphyllobothriidae gen. sp. larvae and calyptrobothrium sp. were recorded as parasites of d. mawsoni for the first time. it seems that toothfish is a postcyclic host of p. gillissi and becomes infected by feeding on muraenolepis (sokolov et al. 2016). corynosoma sp. and echinorhynchus sp. are not included in the list of parasites found for the first time because the poor condition of specimens made proper identification impossible. it should be noted that in the present study larvae of c. bullosum, corynosoma sp. and contracaecum sp. are most likely aberrant parasites of d. mawsoni. since the larvae of these species occur mainly in the body cavity and musculature of fish, their localization in the intestine (table 1) of the examined fishes is atypical. dissostichus mawsoni is most heavily infected by cestode larvae. because of their distribution via planktonic copepods cestodes larvae are wide spread and are found in species of many families: nototheniidae, artedidraconidae, bathydraconidae, macrouridae, channichthyidae, myctophidae and muraenolepididae (rocka 2003). after being planktophagous during their short juvenile period, they then become predatory, feeding variously on bony fish, squid and octopus up to a depth of 2250 m (petrov & istomin 2010). with growth, antarctic toothfish become one of the biggest predators in the antarctic waters (max. �200 cm long) and are only usually eaten by sharks and whales. therefore, tetraphyllidean larvae and plerocercoids, representing the recently created order onchoproteocephalidea (caira et al. 2014), accumulate in this dead-end host, reaching significant infection rates. other than the parasites listed in this study other researchers have found six species of trematodes: helicometra rakusai zdzitowiecki, 1997 in the ross sea (sokolov & gordeev 2013), lecithaster macrocotyle szidat & graefe, 1967, macvicaria pennelli leiper & atkinson, 1914, gonocerca phycidis manter, 1925, lepidapedon garrardi leiper & atkinson, 1914, neolebouria georgiensis gibson, 1976 in the south shetland islands area (zdzitowiecki 1987, 1988, 1991a, 1999). moreover, zdzitowiecki found metacanthocephalus dalmori zdzitowiecki, 1983, corynosoma hamanni linstow, 1892 and corynosoma pseudohamanni zdzitowiecki, 1984 on d. mawsoni in the south shetland islands area (1990). anisakis sp. larvae and pseudoterranova decipiens krabbe, 1878 larvae were found on the same host and in the same area (rokicki et al. 2009) as well as the monogenean neopavlovskioides georgianus kovaljova & table 1 prevalence and intensity of infection and site of parasites in d. mawsoni from the ross and amundsen seas. ross sea (n �20) amundsen sea (n �5) parasite adult (a)/ larva (l) prevalence (%) mean intensity (range) prevalence (%) mean intensity (range) site copepoda eubrachiella antarctica a 60 12 (1�86) 36 3 (1�6) body surface monogenea pseudobenedenia dissostichi a 55 11 (1�36) 40 8 (8) body surface acanthocephala corynosoma bullosum a l 5 10 (10) � � intestine, pyloric caeca corynosoma sp.a l � � 20 1 (1) intestine, pyloric caeca echinorhynchus petrotschenkoi a 10 4 (2�6) 40 9 (9�10) intestine echinorhynchus sp. a 5 2 (2) 20 1 (1) intestine nematoda contracaecum sp.a l 5 1 (1) � � intestine hysterothylacium sp. a/l 100 25 (1�90) 40 23 (32�83) intestine, pyloric caeca, stomach trematoda helicometra antarcticae a 55 33 (1�243) 20 7 (7) intestine, pyloric caeca neolepidapedon trematomi a 50 16 (1�78) 40 113 (22�204) intestine, pyloric caeca proctophantastes gillissi a � � 40 1 (1�2) intestine cestoda onchobothrium antarcticum l 15 39 (1�108) 60 10 (2�21) intestine, pyloric caeca diphyllobothriidae gen. sp. l 15 3 (1�6) 40 1 (1) body cavity, stomach wall calyptrobothrium sp. l 15 173 (6�471) 60 27 (11�57) intestine, pyloric caeca a aberrant parasite. i.i gordeev & s.g sokolov parasites of the antarctic toothfish citation: polar research 2016, 35, 29364, http://dx.doi.org/10.3402/polar.v35.29364 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/29364 http://dx.doi.org/10.3402/polar.v35.29364 gaevskaja, 1977 (gaevskaja et al. 1990). two more monogenean species were found on d. mawsoni in the pacific sector of sub-antarctica and near the palmer archipelago: neopavlovskioides dissostichi dillon & hargis, 1968 and pseudobenedenia nototheniae johnston, 1931 (gaevskaja et al. 1990; oguz et al. 2012, respectively). infection of dissostichus eleginoides smitt, 1898, a congener whose habitat overlaps with d. mawsoni throughout the antarctic, including the ross sea, has been studied in much more depth (brickle et al. 2006; brown et al. 2012). despite similar biology and feeding behaviour (shust et al. 2009; collins et al. 2010), d. mawsoni shares only 5 of 13 parasites recorded for d. eleginoides in the ross sea: h. antarcticae, the tetraphyllidean plerocercoid, hysterothylacium sp., c. bullosum and e. petrotschenkoi (brickle et al. 2005). possible explanations for this are the different size ranges of the samples collected and possibly also that specimens of d. eleginoides were caught close to or inside the in-shelf depressions of the ross sea, where the main food sources of dissostichus spp. are quite different to those on slopes and in deeper water. antarctic toothfish have been found to have low genetic diversity and temporal stability, so that even specimens collected thousands of kilometres apart are genetically similar (mugue et al. 2014). additionally, most tagged and recaptured fish were recorded less than 50 km from the place of their release and only 20% of fish moved more than 50 km (dunn et al. in petrov & tatarnikov 2010). although they form the foundation of an important baseline, our data are limited, and it is therefore difficult to make assumptions about the parasitofauna of d. mawsoni around the antarctic, their biogeography, or indeed their potential as indicators of host biology. however, in their study of the parasites of d. eleginoides caught around antarctica, brickle et al. (2005) discovered that specimens found near heard island, macquarie island and the prince edward islands were the most similar, while those from the ross sea was the most dissimilar, based on sørensen’s similarity index. despite the fact that antarctic toothfish is an endemic to the antarctic, its parasitofauna includes both cosmopolitan as well as the local species found in its congener and other bony fishes. acknowledgements the authors wish to thank drs andrey f. petrov and konstantin v. shust for helping in the material collection, dr nikolay s. mugue for assistance in the dna analysis and dr andrey yu. utevsky for identification of leeches. the work was supported by russian foundation for basic research grant no. 14-04-31950. references aljanabi s.m. & martinez i. 1997. universal and rapid saltextraction of high quality genomic dna for pcr-based techniques. nucleic acids research 25, 4692�4693. andrijašev a.p. 1986. obščij obzor fauny donnyh ryb antarktiki. (review of the bottom fish fauna of antarctic regions.) trudy zoologiceskogo instituta akademii nauk ussr 153, 9�45. bray r.a., gibson d.i. & jones a. (eds.) 2008. keys to the trematoda. vol. 3. wallingford: cabi. brickle p., mackenzie k. & pike a. 2005. parasites of the patagonian toothfish, dissostichus eleginoides smitt 1898, in different parts of the subantarctic. polar biology 28, 663�671. brickle p., mackenzie k. & pike a. 2006. variations in the parasite fauna of the patagonian toothfish (dissostichus eleginoides smitt, 1898), with length, season, and depth of habitat around the falkland islands. journal of parasitology 92, 282�291. brickle p., olson p.d., littlewood d.t.j., bishop a. & arkhipkin a.i. 2001. parasites of loligo gahi from waters off the falkland islands, with a phylogenetically based identification of their cestode larvae. canadian journal of zoology 79, 2289�2296. brown j., brickle p. & scott b.e. 2012. the parasite fauna of the patagonian toothfish dissostichus eleginoides off the falkland islands. journal of helminthology 87, 501�509. byhovskaja-pavlovskaja i.e. 1985. parazity pyb. (parasites of fishes.) leningrad: nauka. caira j.n., jensen k., waeschenbach a., olson p.d. & littlewood d.t.j. 2014. orders out of chaos*molecular phylogenetics reveals the complexity of shark and stingray tapeworm relationships. international journal for parasitology 44, 55�73. calhaem i. & christoffel d.a. 1969. some observations of the feeding habits of a weddell seal, and measurements of its prey, dissostichus mawsoni, at mcmurdo sound, antarctica. new zealand journal of marine and freshwater research 3, 181�190. collins m.a., brickle p., brown j. & belchier m. 2010. the patagonian toothfish: biology, ecology and fishery. advances in marine biology 58, 227�300. gaevskaja a.v., rodjuk g.n. & paruhin a.m. 1990. osobennosti i formirovanie parazitofauny patagonskogo klykaca dissostichus eleginoides. (peculiarities and formation of parasitofauna of the patagonian toothfish dissostichus eleginoides.) biologija morja 4, 23�28. gon o. & heemstra p.c. (eds.) 1990. fishes of the southern ocean. grahamstown: j.l.b. smith institute of ichthyology. hanchet s.m. 2006. species profile for antarctic toothfish (dissostichus mawsoni). paper presented at the working group on fish stock assessment of ccamlr as document wg-fsa-06/26. 9�20 october, hobart, australia. holloway h.l. & bier j.w. 1968. helicometra antarcticae sp. nov. from antarctic coastal fishes. proceedings of the helminthological society of washington 35, 30�34. jensen k., nikolov p. & caira j.n. 2011. a new genus and two new species of anteroporidae (cestoda: lecanicephalidea) parasites of the antarctic toothfish i.i gordeev & s.g sokolov 4 (page number not for citation purpose) citation: polar research 2016, 35, 29364, http://dx.doi.org/10.3402/polar.v35.29364 http://www.polarresearch.net/index.php/polar/article/view/29364 http://dx.doi.org/10.3402/polar.v35.29364 from the darkspotted numbfish, narcine maculata (torpediniformes: narcinidae), off malaysian borneo. folia parasitologica 58, 95�107. juhov v.l. 1982. antarkticeskij klykac. (antarctic toothfish.) moscow: nauka. laskowski z. & rocka a. 2014. molecular identification larvae of onchobothrium antarcticum cestoda: tetraphyllidea) from marbled rockcod, notothenia rossii, in admiralty bay (king george island, antarctica). acta parasitlogica 59, 767�772. littlewood d.t.j., curini-galletti m. & herniou e.a. 2000. the interrelationships of proseriata (platyhelminthes: seriata) flatworms tested with molecules and morphology. molecular phylogenets evolution 16, 449�466. lockyer a.e., olson p.d. & littlewood d.t.j. 2003. utility of complete large and small subunit rrna genes in resolving the phylogeny of the platyhelminthes: implications and a review of the cercomer theory. biological journal of the linnean society 78, 155�173. mugue n.s., petrov a.f., zelenina d.a., gordeev i.i. & sergeev a.a. 2014. low genetic diversity and temporal stability in the antarctic toothfish (dissostichus mawsoni) from nearcontinental seas of antarctica. ccamlr science 21, 1�10. oguz m.c., heckmann r.a., cheng c.h.c. & el-naggar a. 2012. ecto and endoparasites of some fishes from the antarctic region. scientia parasitologica 13, 119�128. petrov a.f. & istomin i.g. 2010. pitanie i piščeviye vzaimootnošenija d. mawsoni norman (perciformes, nototheniidae) v primaterikovyh morjah indookeanskogo sectora antarktiki i na banke banzare. (feeding and food relations of d. mawsoni norman [perciformes, nototheniidae] in the nearcontinental seas of the indian sector of the antarctic and at the banzare bank.) voprosy rybolovstva 11, 817�830. petrov a.f. & tatarnikov v.a. 2010. new data on migrations of antarctic toothfish dissostichus mawsoni in the dumont d’urville sea in the 2008/2009 season. journal of ichthyology 50, 140�141. rocka a. 2003. cestodes of the antarctic fishes. polish polar research 24, 261�276. rocka a. 2004. nematodes of the antarctic fishes. polish polar research 25, 135�152. rocka a. & zdzitowiecki k. 1998. cestodes in fishes of the weddell sea. acta parasitologica 43, 64�70. rodjuk g.n. 1984. novye predstaviteli roda metechinorhynchus (acanthocephala)*parazitov ryb zapadnoj antarktiki. (new representatives of the genus metechinorhynchus [acanthocephala]*parasites of fishes in the western antarctic.) zoologicheskii zhurnal 63, 1893�1896. rokicki j., rodyuk g., zdzitowiecki k. & laskowcki z. 2009. larval ascaridoid nematodes (anisakidae) in fish from the south shetland islands (southern ocean). polish polar research 30, 49�58. shust k.v., kuznetsova e.n., kozlov a.n., kokorin n.v. & petrov a.f. 2005. two species of toothfish in two basis long line fisheries regions*patagonian toothfish in subarea 48.3 (south atlantic) and antarctic toothfish in subareas 88.1, 88.2 (south pacific). paper presented at the working group on fish stock assessment of ccamlr as document wgfsa-05/71. 10�21 october, hobart, australia. shust k.v. & petrov a.f. 2009. on captures of patagonian toothfish dissostichus eleginoides (nototheniidae) in the highlatitude antarctic regions. journal of ichthyology 49, 136�138. shust k.v., zarikhin i.p., istomin i.g., petrov a.f., tatarnikov v.a. & demina n.s. 2009. comparative characteristics of patagonian (dissostichus eleginoides) and antarctic (d. mawsoni) toothfish inhabiting different sectors of the southern ocean. paper presented at the working group on fish stock assessment of ccamlr as document wg-fsa-09/ 24. 12�23 october, hobart, australia. smith p.j., mckenzie a. & tubbs l. 2006. preliminary analyses of an ectoparasite eubranchiella antarctica as a marker for stock discrimination of antarctic toothfish in the ross sea. paper presented at the working group on fish stock assessment of ccamlr as document wg-fsa-06/28, 9�20 october, hobart, australia. sokolov s.g. & gordeev i.i. 2013. new data on trematodes (plathelminthes, trematoda) of fishes in the ross sea (antarctic). invertebrate zoology 10, 255�267. sokolov s.g. & gordeev i.i. 2015. novye dannye o trematodah antarkticeskih ryb. (new data on trematodes of antarctic fishes.) parazitologiya 49, 12�27. sokolov s., gordeev i. & lebedeva d. 2016. redescription of proctophantastes gillissi (overstreet et pritchard, 1977) (trematoda: zoogonidae) with discussion on the systematic position of the genus proctophantastes odhner, 1911. acta parasitologica 61, 529�536. zdzitowiecki k. 1987. digenetic trematodes from the alimentary tract of fishes off south shetlands (antarctic). acta parasitologica polonica 32, 219�232. zdzitowiecki k. 1988. occurrence of digenetic trematodes in fishes off south shetlands (antarctic). acta parasitologica polonica 33, 155�167. zdzitowiecki k. 1990. occurrence of acanthocephalans in fishes of the open sea off the south shetlands and south georgia (antarctic). acta parasitologica polonica 35, 131�141. zdzitowiecki k. 1991a. occurrence of digeneans in open sea fishes off the south shetland islands and south georgia, and a list of fish digeneans in the antarctic. polish polar research 12, 55�72. zdzitowiecki k. 1991b. antarctic acanthocephalan. synopsis of the antarctic benthos. vol. 3. koenigstein: koeltz scientific books. zdzitowiecki k. 1999. digeneans of the families opecoelidae and lepocreadiidae, parasites of lepidonotothen macrophthalma from the north scotia ridge, and remarks on the discrimination of neolepidapedon magnatestis and n. trematomi. acta parasitologica 44, 233�240. i.i gordeev & s.g sokolov parasites of the antarctic toothfish citation: polar research 2016, 35, 29364, http://dx.doi.org/10.3402/polar.v35.29364 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/29364 http://dx.doi.org/10.3402/polar.v35.29364 northern continuation of caledonian high-pressure metamorphic rocks in central-western spitsbergen y. ohta, a. a . krasil'scikov, c. lepvrier and a . m. teben'kov ohta. y., krasil'seikov. a. a., lepvrier, c. & teben'kov, a. m. 1995: northern continuation of caledonian high-pressure metamorphic rocks in central-western spitsbergen. polar research 14(3), 303 315. caledonian low-temperature, high-pressure metamorphic rocks, as first recognised at motalafjella. central western spitsbergen, include characteristic brown dolostone and serpentinite. similar rocks are scattered in the strandflats, along the eastern marginal fault of the tertiary forlandsundet graben, and along thrust faults to the east on both sides of st. jonsfjorden. the mineral chemistries of the constituent carbonates and oxides are diagnostic of high-pressure metamorphic rocks, containing high contents of mgo in the carbonates and c r 2 0 3 in the oxides. based on a surface magnetic-anomaly survey and fault-plane obser vations, some of these rocks are considered to have been pressed up along faults produced by strike-slip faulting during a n early stage of the forlandsundet graben formation. the distribution of these rocks indicates that the high-pressure metamorphic rocks extend as much as 50 km to the nnw from motalafjella to sarsoyra. y . ohta, norsk polarinstitun, p . o . box 5072-majorstua, n-0301 oslo, norway; a . a . krasil'seikou and a . m . teben'kov, polar marine geological expedition, ul. pobeda 24. lomonosou, 189510 st. petersburg. russia; c . lepurier, u r a cnrs 1759, dkpartemenr de gkotectonique, uniuersitk pierre et marie curie, 4 place jussieu, 75252 paris ceder 05, france. introduction a caledonian low-temperature, high-pressure metamorphic complex of subduction-zone origin, the vestgotabreen complex, occurs south of st. jonsfjorden, central western spitsbergen (hors field 1972; ohta 1979; ohta et al. 1983; ohta et al. 1986; hirajima et al. 1984; hirajima et al. 1988). these rocks occur in a thrust complex and are divided into two units based on their metamorphic grade within the typical exposures in motalafjella (fig. 1b). the high-grade division has chloritoid-garnet mica schists with eclogite inclusions, glauco phane-garnet-mica schist, eclogitic metagabbros, omphacite quartzite (kanat 1984; hirajima et al. 1988), and micaceous, schistose marble. the protoliths are thought to be a deep-sea igneous sedimentary succession (ohta et al. 1983). the age of the igneous protoliths for the eclogitic metagabbros is considered to be ca. 1,100 ma, a sm/nd model age, which is possibly an age of mantle derivation (bernard-griffiths et al. 1993). the low-grade rocks are black phyllites with chlorite-sericite assemblages, green phyllites with local pillow and dyke swarm structures and laws onite-pumpellyite assemblages, limestone and quartzite lenses, and green-brown dolostone with fuchsite. small tectonic inclusions of serpentinite occur within the dolostone (ohta 1979; hirajima et al. 1984; teben'kov & korago 1992). the metamorphism is of early caledonian age (ohta et al. 1989, dallmeyer et al. 1990). although typical high-pressure metamorphic rocks are restricted to outcrop from motalafjella to sw holmesletfjella, green-brown dolostone and serpentinite similar to those in the low-grade unit of the high-pressure complex are found at isolated localities in the western part of oscar i1 land, north of st. jonsfjorden. the green-brown dolostone with fuchsite is genetically related to the hydration of ultramafic rocks (teben'kov & korago 1992) and is easily recognisable in the field. this rock type and associated serpentinite occur at ankerfjellet, the eastern and southern parts of kaffieyra and as far north as sarsoyra. the last locality is ca. 50 km nnw from mot alafjella. these distinctive rocks follow thrust faults in mountainous areas to the east of the forlandsundet graben, but most of those in the strandflat areas within the graben are isolated due to extensive cover of tertiary and quaternary sediments. this paper presents mineralogical evidence to distinguish the green-brown dolostone of the 304 y . ohta et 01. & a 3 i b i fig. /.gicncralised geological map around forlandsundet, from sarsciyra to eidembukta. with an index map a . index map. western part of spitsbergen. explanation: obliquely lined, tertiary fold-thrust zone: horizontally lined, ba\ement rock\. place names: k n . kinnefjellet: pr, protektorfjellet: o r . orustdalen; re. recherchefjordcn; r a . raudfjcllet: k v . kvivrt)dden. t h r square indicates the area of the map at right b gecilogical map. explanation: 1, tertiary: 2. carboniferous. 3. upper ordovician-middle silurian: 4. vendian tilloids; 3. late proterozoic successions. excluding the vendian tilloids: 6 and 7. st. jonsfjorden group: 6, calc-argillaceous phyllites (alkhornet formation). 7. quartzite and phyllites (lsvliebreen formation). 8. garnet-biotite whist5 (the mullernesset formation i n s w s i . jonsfiorden and the pinkie formation at bourrefjellet in prins karls forland); 9 , high-pressure metamorphic complex around motalafjella: 10, schists and gneisses in breggerhalwya: 11. lithological boundary; 12. fault and thrust the white areas are c o w r e d bv glacier,. b = bulltinden. <: = copper camp. t = thorkelsenfjellet. northern continuation of caledonian high-pressure metamorphic rocks 305 high-pressure metamorphic complex from other carbonate rocks. their distribution can be cor related with high magnetic-anomaly zones along the eastern margin of the forlandsundet graben; these zones reflect the tertiary fault pattern, which is examined kinematically with respect to the fault-plane observations. distribution of the green-brown dolostone and serpentinite the high-grade unit of high-pressure meta morphic rocks in motalafjella occurs as a thrust sheet above the low-grade unit, and the latter is unconformably covered by the late ordovician middle silurian flyschoids. the low-grade unit and the flyschoids together form an upper limb of an overturned syncline, therefore, the low-grade unit structurally overlies the flyschoid strata (ohta et al. 1983). a green-brown dolostone in motalafjella occurs in the lowest structural position of the low grade unit, with a thickness of 50-80 m (hirajima et al. 1984; teben’kov & korago 1992), directly in contact with structurally underlying, but younger basal conglomerate, 0-5 m in thickness, of the flyschoid sediments, which contains subangular clasts of the green-brown dolostone and ordo vician gastropods in the matrix (ohta et al. 1983). a grey limestone occurs structurally below (strati graphically above) the basal conglomerate, and a thick conglomerate even below this limestone contains boulders of the green-brown dolostone. some grey limestones form olistostromes in this conglomerate and include late ordovician to middle silurian corals and gastropods (scrutton et al. 1976) and conodonts (armstrong et al. 1986). these rocks and the stratigraphically over lying sandstone-shale succession (table 1) have been termed the bulltinden group and are of flysch origin (harland et al. 1979). the high pressure metamorphism has been dated ca. 475 ma by the 40ar/39ar and rb/sr mica whole rock methods (dallmeyer et al. 1990) and is older than the unconformity. this geological relationship is exposed in the two ridges to the north of motalafjella and southernmost part of bulltinden (fig. 1b). the unconformity has locally been disturbed by thrusts. the overturned syncline of the late ordovician to middle silurian bulltinden group, which occurs to the east of the high-pressure meta morphic rocks, has a moderately west-dipping axial surface. along the lower limb of this syncline, a thin green-brown dolostone and some black phyllites occur below the grey limestone of the bulltinden group on the south-eastern ridge of holmesletfjella and crop out discontinuously along a thrust on the cliffs from middle-north to north-western holmesletfjella to copper camp (fig. 1b). the dolostone is thrust over the alk hornet formation (areno-argillaceous phyllites and marble layers) of the st. jonsfjorden group (harland et al. 1979; hjelle et al. 1979; berg et al. 1993) of probably middle proterozoic age. the thrust surfaces have moderate westerly dips at eastern holmesletfjella and motalafjella. similarly discontinuous outcrops of the green brown dolostone are found from the northern foothill of bulltinden to the flat area between thorkelsenfjellet and bulltinden. ca. 200 m from the southern shore of st. jonsfjorden, and their cleavages are almost horizontal (fig. 1b). on the middle slopes of ankerfjella on the northern side of st. jonsfjorden, thin and discontinuous lenses of green-brown dolostone occur along roughly horizontal thrusts on both the southern and north ern sides of the mountain, bounding the vendian tilloids and the st. jonsfjoden group below and the conglomerate and shale-sandstone suc cessions of the bulltinden group above. table 1. lithostratigraphy in oscar i1 land (modified from berg et al. 1993). paleogene middle carboniferous early devonian late ordvician-middle silurian vendian late proterozoic middle proterozoic sandstones, conglomerates sandstones. carbonates conglomerates bulltinden group sandstone-shales grey limestones conglomerates comfortlessbreen group diamictites (tilloids) daudmannsodden group pelitic phyllites carbonates vestgotabreen high-pressure metamorphic complex st. jonsfjorden group alkhornet formation (carbonate-phyllite succ.) l0vliebreen formation (quartzite-phyllite succ.) 306 y . ohta et al. _ _ _ ~ i , / andrcnsbrcen % firnisundct fig. 2 . high magnetic-anomaly segments and zones (simplified from krasil'stikov et al. 1995). a. s a r s ~ y r a , with the profile a b (lower figure). showing calculated magnetic-causative rock bodieb: black = serpentinites, dotted = metahasic rock. s and d , refer to fig. 5. a t snippen, on the southern coast of k a f f i ~ y r a (fig. 2b ), narrow serpentinite lenses are interbed ded with green and purple phyllites within a shea red zone of ca. 100 m width, which bounds the tertiary sediment to t h e west. a similar ser pentinite and green phyllite assemblage occurs discontinuously along t h e northeastern foothills of k a f f i ~ y r a . scattered outcrops of the basement rocks within t h e forlandsundet g r a b e n in eastern k a f f i ~ y r a have dips of more than 30" to the east or northern continuation of caledonian high-pressure metamorphic rocks 307 west with nnw strikes. this structure is distinctly different from complex thrust duplexes which lie to the east of the graben margin fault. a ca. 1-3 m thick, strongly sheared serpentinite with talc-rich'slip planes occurs with a 3 m wide sheared conglomerate adjacent to the east along a river within the northern moraine of aavats markbreen at the foothills of southeastern sarsoyra (fig. 2a). the conglomerate has undeformed quartzite clasts in a greenish brown, weakly phyllitic sandy matrix and is similar to the conglomerates of the bulltinden group. to the east of the conglomerate are green phyllites, poss ibly a member of the vendian tilloid succession, bounded by a shear zone. to the west of the serpentine are black and green, shaly-sandy phyl lites with thin intraformational conglomerate, quartzite and grey limestone layers, the aavats markbreen formation of waddams (1983) and harland et al. (1993). they considered this for mation the uppermost formation of the vendian tilloid succession, but it is better correlated with the sandstone-shale succession of the upper part of the bulltinden group, based on paleozoic microfossils recently found in massive limestones near northernmost sarsoyra (makarjev, pers. comm. 1992). scrutton et al. (1976) also reported paleozoic fossils from southern sarsoyra. the cleavages in these metasediments are steep, 40 70" to the east and west, and many tight folds are expected. similar occurrences of serpentinite associated with brown-weathered dolostone lenses have been found along the foothills in eastern sarsbyra. in addition, seven localities of brown dolostone with green fuchsite clots occur in the middle part of sarsoyra (fig. 2a). these green-brown dolo stones and serpentinites are considered to be members of the low-grade, high-pressure meta morphic complex, as discussed later. the thrust sheets comprising the high-pressure metamorphic rocks have moderate west dips in the eastern localities at southeastern holmeslet fjella and motalafjella, but northwest of bulltin den and around ankerfjella they are almost horizontal with gentle open synform structures. these structural features and scattered occur rences of serpentinite and green-brown dolostone in the strandflats suggest that the thrust sheets, including the high-pressure metamorphic rocks, occur in the subsurface of kaffioyra and sarsoyra to the north. the moderate-steep structures of the basement rocks near the foothills were formed by later tertiary deformations. diagnostic minerals of the green brown dolostone the green-brown dolostone at motalafjella is white to grey on fresh surfaces, and is mostly massive with many local thin quartz veins in an irregular network; it has mm-to-cm scale irregular green clots with diffuse margins and scattered opaque grains. schistose structure, marked by fine-grained layers, is present locally and the cleavages are partly marked by green colour. local sulphide and ankerite-siderite mineral isations are also seen. serpentinite bodies of metres t o tens of metres size are included in the phyllites and dolostone, commonly enclosed by conformable slip-cleavages. the dolostone has 10-23 wt% cao only within or near sheared zones; massive parts have less than 5 wt% cao (commonly 1-2 wt%) and 23 36 wt% of mgo (table 2). thus, this carbonate rock is primarily magnesite-stone that has been modified along the sheared zones into dolostone. total feo averages 5 w t % , but locally in the sheared zones this increases to 7% (teben'kov & korago 1992). table 2. chemical compositions of rocks and constituent min erals of the green-brown dolostones from various localities. rock mineral 1 2 3 4 5 6 7 s i 0 2 t i 0 2 a1203 feo* mno cao n a 2 0 kzo cr203 nio total mgo 12.15 32.80 0.06 2.51 1.48 4.34 6.08 0.14 0.17 14.86 36.36 26.33 3.16 0.72 0.18 0.25 0.11 _ _ 61.36 80.34 0.03 0.00 0.02 0.25 0.02 0.02 0.00 0.04 3.76 0.01 0.00 0.01 0.01 4.25 4.57 3.66 3.88 0.11 0.21 0.04 0.02 44.41 17.61 18.00 46.31 45.23 0.18 30.48 30.50 0.02 0.88 0.01 0.00 0.00 0.00 0.02 0.01 0.00 0.00 0.08 0.00 0.00 0.00 0.00 0.00 0.24 0.00 48.35 52.62 53.31 50.30 50.31 1 , 2 representative dolostone and magnesite-stone, both from motalafjella (teben'kov & korago 1992). 3-7 new mineral analyses by empa: 3. magnesite from motalafjella; 4 and 5, dolomites from ankerfjella; 6 and 7, magnesites from sars~yra. 308 y . ohta et a l . t u b k 3 . chemical composition of fuchsites. new data by empa. i 3 4 > h slo: tiol ' 4 1 2 0 , feo' m n o c a o na,o kzo cr,o, n10 total mgo 48.42 46 91 48.96 48.04 46.89 46.22 0 . 0 5 0 03 0.12 0.11 0.08 0.07 27.46 26.12 3 2 . 0 9 30.88 25.39 21.92 0.02 0 02 0 02 0.00 0.00 0.00 1.61 2 31 1 . 6 1 1 6 9 1 . 2 1 1.39 0.10 0 !i3 0.05 0.07 (i 18 ij 22 0.21 0.23 0.39 0.32 7.94 8 . 0 3 9.27 9.65 8.58 9.20 9.39 9 (16 1.40 2 82 11.81 11.12 (1.15 i176 0.05 0.01 95.68 93.yl 95.31 91.03 94.53 93.51 0.46 o 41 (i 5 3 n.s3 0.15 0 27 1 dnd 2 , from motalaflella. 3 and 4. frum ankerfjella. 5 and 6. from s a r s q r a the analyses of carbonate minerals from mass ive dolostone of motalafjella also show pure magnesite with less than 0 . 2 w t % c a o and 44 wt% m g o (table 2). the green mineral is the chromium-bearing. (ca 10 wt% c r , 0 3 ) white mica. fuchsite (table 3). the chromium contents a r e higher than that of some metamorphic rocks. which have commonly 2-5 wt% of crzo,, and this is indicative of a close genetic relationship of the fuchsite with an ultramafic rock. the opaque minerals are chromite. some with more than 4 8 w t % cr203. and chromian spinel (table 4 ) . t h e analysed chromites from motala fjella contain variable amounts of z n o , 3 18 wt%, especially around the margins of grains. as much as 3 wt% z n o has been reported from sagvandite in northern norway (donath 1931), but 13-18 w t % in t h e present minerals a r e exceed ingly high. t h e low a1203 contents in these min erals show that the z n is not in the form of spinel o r gahnite, but possibly in the form of oxides or wlphides (s has not been analysed). later sulphide mineralisation in the sheared zones may have partly modified the marginal parts of the chromite. t h e chromian spinels from sarsoyra also contain some amounts of z n o (table 4). their host dolostones are from sheared parts with later sulphide mineralisation. fuchsite and chromium-bearing minerals, together with magnesite, provide critical evidence for a n ultramafic affinity of the dolostone (o'hara 1967). and they discriminate these rocks from other carbonate rocks of sedimentary origin present in the area. carbonate minerals of simllar dolostones from ankerfjella and s a r s ~ y r a have been analysed by an e m p a as shown in tables 2 , 3 and 4 . they also have magnesite composition and are associ ated with chromium-bearing minerals demon strating that these rocks, scattered as far north as northern sarsoyra, belong t o the high-presure metamorphic complex. the extent of the high pressure metamorphic rocks is, therefore, about so km in a nnw-sse direction. ruble 4 c'hemical cornpusitions of chrornites and ~ h r o m i a n spinels. new data by empa siol ti0: a1?0, feo' m n o c a o ua.0 k 2 0 c r 2 0 , vio zno total mgo 7 i 3 4 5 6 7 8 9 10 11 0 5 0 0.511 0.yj 0 so 0.08 0.08 0.59 0.79 0.00 0.03 ~ 0.03 0.04 0 2 1 0 . 1 8 0.04 0.04 8.06 10.58 9.44 9.06 31.21 79.58 3 . w 4.10 28.55 28.95 32.04 i4.8o 29.44 21.93 21.46 14.34 20.25 44.08 43.68 14.36 11.15 13.13 o.(x) 0.00 0.m) ( i 00 u 1 1 0 28 (1.21 0.14 0.12 0.13 0.58 1.72 0.87 0.80 14.60 8.11 0.30 0.30 14.84 15.10 15.81 .0.01 (1.00 0.04 0.00 0.00 0 . 0 0 0.00 0.(mi 0.oc 0 mi 0.04 0 . 1 1 0.14 0.09 0.01 0.00 0 . i m j 0.ml o.(xi 0.00 0.03 (1.04 0 0 2 0.02 0.00 5 3 201 47.96 48.89 51.00 36.99 3 4 7 3 44 63 42.35 4 1 18 41.54 38.87 0 1x1 0 ( x i 0.00 0.03 0.09 0 08 0 3.7 0 . 5 1 0 04 0 . 2 3 0.21 0.11 17.96 2 86 13.51 12.94 94 m ) 92 56 94.64 95.29 97.53 93.33 y3.64 y 2 16 w 14 100.17 101.20 .. . 12 13 14 28.38 30.94 30.17 28.03 19.92 20.62 2.19 9.60 8.19 34.88 36.25 36.20 0.19 0.14 0.00 6.03 3.55 4.59 99.70 100.40 99.77 1-4 ankerfjella. 7 1 4 from motalafjella 1 = rim of chromite: 2 = core of 1: 3 and 4 = homogeneous chromites: 5 and 6, chromian spinels from from s a r s q r a : 7 and 8 = chromites; 9. 10 and 11 = chromian spinels; 12. 13 and 14 = zn-rich chromian spinels. northern continuation of caledonian high-pressitre metamorphic rocks 309 table 5 . chemical composition of chloritoids (new analyses by empa) from a tertiary grltty sandstone on the river hed in the northern moraine of aavatsmarkbreen. mg/fe: mg/fe* + mg (fe* = total fe as fe”). 1 2 3 4 5 6 7 8 9 10 s o z 24.32 24.57 24.52 24.58 24.43 24.66 24.50 24.68 24.38 24.71 alzo, 39.09 38.78 38.46 39.94 39.93 40.57 40.32 40.23 39.99 40.21 feo* 25.49 26.07 25.57 26.94 25.88 23.81 23.87 23.83 24.14 23.91 mno 0.47 0.59 0.51 0.25 0.19 0.77 0.84 0.85 0.89 0.83 mgo 2.00 2.18 2.28 1.01 1.03 1.87 1.59 1.74 1.42 1.63 total 91.37 92.19 91.34 92.72 91.46 91.68 91 12 91.33 90.82 91.35 mg/fe 12.30 14.60 13.70 6.40 6.60 12.30 10.60 11.50 9.50 10.80 detrital chloritoid grains a tertiary conglomeratic sandstone exposing on the river bed along the northern side of aavats markbreen moraine contains detrital chloritoid grains in its matrix, as much as 0.2 volume percent. the chloritoid grains are fresh and angu lar in shape, indicating a short transport distance. it is assumed that the weathering was of short duration and that the grains were moved as stream bed load. this rock also contains cm-size clasts of limestone with fragments of late paleozoic fossils. because carboniferous rocks are assumed to occur widely in this area before the devel opment of tertiary graben (gabrielsen et al. 1992), the sources of the sandstone materials are considered to be local. the chloritoid may have been supplied from the low-pressure meta morphic rocks exposed together with the ser pentinite in the foothills of southeastern sars0yra. the mg/mg + fe* ratios (fe* = total fe as fe+*) of the detrital chloritoid grains (table 5 ) are similar to those of the chloritoid rims in the chloritoid-bearing schists of the high-pressure metamorphic complex (ohta 1979; hirajima et al. 1988), but not to those occurring on prins karls forland (manby 1983) (fig. 3). it is not likely that the chloritoid grains were transported from prins karls forland across the graben. given the angularity of the grains and their amount, and the lack of this mineral in the tertiary sediments in kaffioyra, it is unlikely that these chloritoid grains had been transported from the motalafjella area for ca. 50 km along the eastern margin of the forlandsundet graben basin. possible southern continuation of the high-pressure metamorphic rocks the extent of the high-pressure metamorphic rocks to the south of motalafjella is not known. however, a metabasic rock lense on the north western slope of kinnefjellet, ca. 5 km south of motalafjella (fig. l a ) , has amphiboles with a winchite core and actinolite margin (ohta et al. 1992); winchite is an indicator of high-pressure metamorphism of moderate temperature range (hirajima et al. 1988). other metabasic rocks on the northern slope of protektorfjellet (fig. l a ) , fig. 3. comparison of the mg/fe* + mg ratios of the chloritoids. white, from motalafjella (ohta 1979 and hirajima et al. 1988); dotted, from prim karls 0 ) forland (manby 1983a); z 15. c 5 10. black, detrial chloritoid f grains in a tertiary 5 . analyses by empa). 60 50 40 30 20 10 conglomeratic sandstone, southern s a r s ~ y r a (new fe’ =total fe as fe+*. mgiiwg + fe* 310 y . ohta et al. ca. 2 0 k m sse of motalafjella, have a pumpellyite-prehnite-chlorite-epidote assem blage (ohta et al. 1992). a brown dolostone, with a small amount of fuchsite with 1 . 7 w t l c cr,03 has been reported by hjelle (1962) from n e of liknausen in orustdalen (fig. 1a) in southern nordenskiold l a n d , between isfjorden and bellsund, ca. 50 km south of motalafjella. if these rocks represent signs of the high-pressure metamorphism, the distribution of high-pressure metamorphic rocks becomes roughly 100 km in length. farther to the south at asbestodden, west of recherchefjorden (fig. 1a) on the southern side of bellsund, a serpentinite with asbestos veins occurs in a limestone-rich phyllite succession of late proterozoic age (dallmann e t al. 1990). sul phide and ankerite-siderite mineralisations, characteristic along some thrust zones around motalafjella (teben'kov & korago 1992), have also been described from raudfjellet (fig. 1 a ) in northwest hornsund and kviveodden (fig. 1 a ) on the southern coast of hornsund (czerny et al. 1992a, b) with some sulphides. these min eralisation zones could be an extension of the thrust-dominated zone (senso lato) involving sheets of the high-pressure metamorphic rocks, although these rocks a r e not exposed on the present surface. reference to the surface magnetic anomaly patterns t h e scattered distribution of very small, green brown dolostone and serpentinite outcrops in sarsoyra were considered by some geologists to possibly be quaternary glacial erratics. however. a recent surface magnetic-anomaly survey over the area (krasil'sfikov et al. 1995) shows that distinctly high, positive-anomaly zones coincide exactly with the localities of these rocks (fig. 2a). examinations of magnetic susceptibility o n various rock samples showed that the green brown dolomites, serpentinites, some magnetite than a few hundred metres wide, and they extend roughly in a n-s direction for approximately 1 4 km in sarscbyra (fig. 2a). a distinctive easternmost high-anomaly zone along the foothills of sarscbyra, which coincides with t h e eastern marginal fault of the tertiary forlandsundet g r a b e n , has a n n w trend and consists locally of a left-stepping en echelon arrangement of the high-anomaly segments within the zone (figs. 2a and 4). another high-anomaly zone in the western part also has similar trend and en echelon arrangement of the high-anomaly segments. while nne-ssw trending discon tinuous zones in the middle part of s a r s ~ y r a shows a right-stepping en echelon segments in its north ern part. these three high-anomaly zones sep arate s a r s ~ y r a into two subareas: n w and se (fig. 4). t h e nw subarea has an acute edge to the south a n d the se subarea shows pointing edge t o the north. this subarea pattern infers a sinistral strike-slip or transpressional movement which formed these subareas near t h e eastern margin of the forlandsundet graben. if this is the case, t h e n n w trending high-anomaly zones to the east and west of sarscbyra consisted of left-stepping segments, can be explained as dextral strike-slip or transpressional fault zones with antithetic faults (lowell 1972; wilcox e t al. 1973). t h e small angles between t h e high-anomaly segments and the zones can be interpreted by a flattening of kapp graarud bearing green phyllites and mesozoic dolerites in t h e strandflat are the causative rocks of these high. positive-anomalies. this correlation fig. 4. schematic interpretation of the fault movemcnts along the high magnetic-anomaly zones in sarseyra. explanation of the arofile: dotted area. tertiarv sediments: broken hatched ~~ indicates that the small scattered outcrops are bedrock exposures. the results of the magnetic survey show t h a t distinctive high-anomaly segments are concen trated in narrow zones. t h e segments are less area, late ordovician-middle silurian; white, precambrian: black. the green-brown dolostone and serpentinite; broken line. f a u l t . surface of the profile: solid lines indicate boundarles of high-anomaly zones; open arrows, inferred movement sense. displacement by supposed strike-slip movements are sche matically shown by strain ellipsoids. northern continuation of caledonian high-pressure metamorphic rocks 31 1 the zones to rotate the segments by later near orthogonal compression, as mentioned later. these explanations of the sense of fault move ment can be debated; however, the present data do not allow any more solid conclusion, due to very poor exposures around the high-anomaly segments. it will be safe to state that the en echelon arrangements of the segments within the high-anomaly zones indicate a strike-slip move ment along the eastern marginal fault of the for landsundet graben. the occurrences of serpentinite and green brown dolostone coincide with the high-anomaly segments. the green-brown dolostone is very solid in thick layers, but it is strongly brecciated and sheared together with phyllites at all occur rences in the strandflats. thus, this rock is sup posed to be pressed up, together with incompetent serpentinite, along the antithetic faults. the high magnetic anomalies can be modelled to be narrow, steeply west-dipping plates reaching as deep as ca. 5 0 m . (krasil’seikov et al. 1995) (fig. 2a, lower figure, and fig. 4). it seems that the steep inclinations of the causative rocks result in the high, positive-anomaly segments. but in other places the same rocks have an almost hori zontal, thin sheet structure at ca. 50 or more metres depth; there they do not show any dis tinctive high-anomaly, but apparently smooth, near normal magnetic fields, due to their small vertical thicknesses. a weak, but similar, pattern of the high mag netic-anomaly segments and zones is recognisable in the eastern margins of kaffi~yra (fig. 2b). an indistinct left-stepping en echelon arrangement of high-anomaly segments can be seen in this zone, which coincides with the eastern marginal fault of forlandsundet graben. scattered exposures of the green-brown dolostones, serpentinites and some other magnetite-bearing phyllites occur along this zone and a short, n-s trending zone around snippen. in western kaffi~yra, the magnetic high-anom aly segments are not as distinctive as in the middle part of s a r s ~ y r a , possibly due to thicker tertiary cover as in the westernmost part of sarseyra. however, the general similarity of the high-anom aly patterns in kaffi~yra and sarseyra implies similar underlying magnetic causative rocks, including the green-brown dolostone and ser pentinite of the high-pressure metamorphic com plex. fault plane observations and tertiary movements the eastern margin of forlandsundet tertiary graben is bounded by steeply dipping, 320-360” striking fault segments. the tectonic development of this basin comprises several episodes of post depositional brittle deformation, also revealed by the paleostress state evolution in the tertiary strata (lepvrier & geyssant 1985; lepvrier 1990; gabrielsen et al. 1992; kleinspehn & teyssier 1992). the graben-like aspect is due to a late phase of extension/transtension and has devel oped in early oligocene in relation with the plate tectonic reorganisation which occurred at that time. prior to this late event, the basin had suf fered a phase of near-orthogonal compression during eocene time (lepvrier 1990; gabrielsen et al. 1992), and the marginal faults are cross-cut and offset by a conjugate set of the wnw-ese and wsw-ene striking strike-slip faults (fig. 1b). a still older strike-slip or transpressional phase can be proposed as suggested by the exist ence of a first set of structures (lepvrier 1990; gabrielsen et al. 1992) and by the interpretation of the high magnetic-anomaly segments and zones. a similar three-stage structural evolution, including successively dextral transpression, con traction and extension/transtension, is observed for the kinematics of tertiary deformation in the west-spitsbergen fold-and-thrust belt (braathen & bergh 1995). based mainly on the regional plate-tectonic setting, it has been suggested that the for landsundet tertiary basin developed initially as a transtensional zone between right-stepping dex tral wrench faults in a general regime of tran spression (lowell 1972; steel et al. 1985; ohta 1982, 1988; lepvrier 1988; gabrielsen et al. 1992). this pull-apart model for the forland sundet graben is consistent with sedimentological observations (rye-larsen 1982) and the inter pretation of the magnetic-anomaly patterns (kra sil’seikov et al. 1995), but structural kinematic indicators for strike-slip movement are rare. within the tertiary deposits cropping out near the eastern margin of the basin, observed fault striae on small-scale fault planes are related only to the episodes of compression and final extension/transtension. these can be seen along the northwestern coast of s a r s ~ y r a , in the pale ogene sarsbukta formation, north of aavats markbreen (locality s in fig. 2a) and around 312 y . uhta et al. a 6 2 1 8 0 " . 800 3 r = 0 8 8 6 6 3 300o. 5 o 6 r = 0.139 v 0 3 186'. 32o r = 0.602 u 3 . 340°, 1 0 0 n e n c u ? 3 1 " . 14o s r = 0 3 7 2 0 3 1 2 3 " . l o o u l : 1 8 8 o . 83o 02: 540, 50 s r = 0.506 u 3 323". 5" northern continuation of caledonian high-pressure metamorphic rocks 313 snippen in southern kaffi~yra (lepvrier 1990), where movements in relation to these two suc cessive episodes of faulting can be seen on ne sw and e-w to ese-wnw striking sets of fault planes (fig. 5d and e). the fault-planes have not been restored to their pre-folding/tilting orien tations in fig. 5d. however, the pitches of the striae are nearly similar to the dips of the beds, the poles of which are shown by small open circles i n fig. 5d. these fault striae will be roughly horizontal, when the beds are rotated to the hori zontal position. the slip-movements which formed these striae took place prior to the folding/ tilting during the earliest stage of the com pressional event. only the final extensional event (fig. se), in part observed on the same fault planes and marked by dip to oblique slip move ments, occurred after the folding/tilting of the strata, and its rotation is assumed to be very small. instead of pure extension, the nw-se direction of the minimum stress axis at that location, with respect to the marginal faults, better corresponds to a regime of transtension. a variable direction of this stress axis during the latest kinematic epi sode has been observed over the length of the basin (lepvrier 1990). near the eastern marginal fault in the basement rocks around dahltoppen (locality d in fig. 2a), fault activity was also multiphase, and super imposed slip striae have been observed on several nnw-sse trending fault-planes. prior to the compressional (fig. 5b) and extensional/transtensional events (fig. 5c) simi lar to fig. 5d and e , an earlier striae-set has been recognised, and they show dextral strike-slip movements on the fault planes (fig. sa), which is in agreement with the estimated dextral move ment from the magnetic-anomaly patterns. these faults are cut by those on which the compressional striae are distinct. the nne-ssw striking fault set may correspond to the pseudo-conjugate sin istral fault planes (figs. 4 and 5a). it is natural that the basement has experienced the folding/ tilting that occurred in the adjacent tertiary strata, which show less than 35" westerly dips in this part of the area. but this rotation did not modify the orientations of dextral strike-slip striae on the nnw-sse fault-planes which would be only somewhat steeper in their pre-folding/tilting orientation. the basement under the folded ter tiary cover does not need to have been folded as block-faulting/tilting of the basement could flexure the cover sediments. tight fold structures have been observed in the sliver of carboniferous rocks in svartfjella, south west of st. jonsfjoden (ohta 1988). the folds have 45-65" west-plunging axes. these structures are cut by the younger extensional faults parallel to the eastern marginal fault of the graben, and could be drag folds related to the tertiary tran spression (lepvrier 1988, 1990). conclusions the green-brown dolostone, actually a magnesite stone, with fuchsite and accessory amounts of chromite and chromian spinel, is an important component of the low-grade, high-pressure metamorphic complex of motalafjella and i t is commonly accompanied by tectonic blocks of serpentinite. these two rock types can be used to trace the distribution of these high-pressure metamorphic rocks. similar dolostone and serpentinite occur north of st. jonsfjorden as far north as sarsoyra. they follow along thrusts at holmesletfjella and ankerfjella, along steep faults near the eastern margin of the tertiary forlandsundet graben, and as scattered outcrops on the strandflats. mineralogical study on the diagnostic minerals in the green-brown dolo stones from these areas suggests an affinity with the high-pressure metamorphic rocks and, accordingly, indicates that the complex extends ca. 50 km to the north-northwest from motala fjella. these rocks have high, positive magnetic sus ceptibility and clearly mark high magnetic-anom aly segments and zones on the strandflats. one of the high-anomaly belts coinciding with the eastern marginal fault of the forlandsundet graben con sists of a left-stepping en echelon arrangement of fig. 5. successive fault movements observed on fault planes. all are lower hemisphere projections. a , b and c, dahltoppen (locality d in fig. 2a) within the basement of southern sarsbyra; d and e, tertiary rocks of the sarsbukta formation on the river bed in the moraine north of aavatsmarkbreen (locality s in fig. 2a). note that all the projections have not been restored to their primary orientations. a . phase i , dextral transpression. b and d , phase 11, compression; c and e , phase 111, extension/ transtension. small open circles in d and e = poles of bedding plane, stars with 5 , 4 and 3 projections = maximum (ol), intermediate (02) and minimum (03) principal stress axes, respectively, and their positions are given in degrees at the lower-left corner. azimuth and plunge value (r = 02 03/01 0 3 ) is shown at the lower-right corner. 314 y . ohta et al segments associated with the green-brown dolo stone and serpentinite. this is considered t o sug gest a strike-slip movement along the marginal fault. successive fault movements have been rec orded on the fault planes as superimposed striae. acknowledgemenrs. constructive discussions were kindly given by w. k. dallmann and a . hjelle. norsk polarinstitutt. k. l kleinspehn and c. teyssier. university of minnesota. u.s.a. we thank k. l. kleinspehn for improving the english. the comments of the two referees are also deeply acknowl edged references armstrong. h. a.. nakrem.h. a . & o h t a . y . 1986: ordovician conodont, from the bulltinden formation. motalafjeua. cen tral-we<tcrn spitsbergen. polar res. 4 . 17-23. berg. s g . . ohta. y . . andresen. a , . maher. h. d . . braathen. a & dallmann. w. k . 1993: st. jonsfjorden. geolodcal map of svalbard 1 : 1oo.ooo. sheet beg, preliminary edition. norsk polarinstitutt. oslo. bernard-griffiths. j . . peucat, j . j . & ohta, y. 1993: age and nature of protoliths in the caledonian blueschist-eclogite complex of western spitsbergen: a combined approach using u-pb. sm-nd and r e e whole-rock system. lirhos 3 0 . 81 90. braathen. a . & bergh. s. g . 1995: kinematics of tertiary deformation in the basement-involved fold-thrust complex. western nordenskiold land. svalbard: tectonic implications based on fault-slip data analysis. tecronophysics 249. 1-29. czerny. j . lipien, g . . manecki. a . & piestrzynski. a . 1992a: geology and ore-mineralization of the hecla hoek succession (precambrian) in front of werenskioldbreen, south spits bergen. stud. geol. pol 98. 67-103. czerny. j . plywacz. i & szubala. l . 1992b: siderite min eralization in thc hecla hoek succession (precambrian) at strypegga, south spitsbergen. srud. geol. pol. 98, 165-170. dallmann. w. k.. hjelle, a , . ohta. y.. salvigsen, 0.. bjor nerud, m. g . , hauser. e. c.. maher. h . d. & craddock, c. 1990: geological map svalbard 1: 1oo.ooo, sheet b l l g van keulcnfjorden. norsk polarinsr. temakarr nr. 15'. 58 pp. dallmeyer. r . d . . peucat. j . j . . hirajima. t . & ohta. y . . 1990: tectonothennal chronology within a blueschist-eclogite complex. west-central spitsbergen. svalbard: evidence from "ar/"ar and rb-sr mineral ages. lirhos 24, 291-304. donth. m. 1931: zink-bearing chromite. a m . mineral. 16.484. gabrielsen. r . h . . k l ~ v j a n . 0. s . . haugsbci. h . . m i d b e . p. s.. nmtvedt. a , . rasmussen. e . & skott. p. ti. 1992: a structural outline of forlandsundet graben, prim karls for land. svalbard. norsk grol. tiidrkr. 72. 105-127. harland. w. b.. hambrey, m. j . & waddams, p. 1993: the vendian geology of sbalhard . y o r ~ k polorirrtr. skr. 193. 150 pp harland. w . b.. horsfield. w . t . . manby. g . m . & morris, a . p. 1979: an outline pre-carboniferous stratigraphy of central western spitsbergen. norsk polarbur. skr. 167. 11% 144. hirajima. t.. hiroi, y. & ohta. y . 1984: lawsonite and pum pcllyite trom vestgotabreen formation in spitsbergen. norsk geol tidskr. 6 4 . 267-274. hirajima, t., banno, s., hiroi. y. & ohta, y. 1988: phase petrology of eclogite and related rocks from the motalafjella high-pressure metamorphic complex in spitsbergen (arctic ocean) and its significancc. lirhos 22. 75-97. hjelle. a . 1962: contribution to the geology of the hecla hoek formation in nordenskiold land, vestspitsbergen. norsk polarinst. arbok 1961, 8 s 9 5 . hjelle, a , . ohta, y . & winsnes, t . s. 1979: hecla hoek rocks of oscar i1 land and prins karls forland, svalbard. norsk polarinst. skr. 167. 14s169. horsfield, w. t . 1972: glaucophane schists of caledonian age from spitsbergen. geol. mag. 109. 2%36. kanat, l. h . , 1984: jadite from southern oscar i1 land, spits bergen. mineral. mag. 48, 301-303. kleinspehn, k. l. & teyssier, c. 1992: tectonics of the pale ogene forlandsundet basin, spitsbergen: a preliminary report. norsk geol. tidskr. 72. 9 s 1 0 4 . krasil'sfikov, a. a,, kubansky, a. p . & ohta, y . , 1995: surface magnetic anomaly study o n the eastern side of the forlandsundet tertiary graben. polar res. 14(2). s-s68. lepvrier, c . 1988: relais compressifs et distensifs entre dec rochements dans la chaine tertiaire du spitzberg. (svalbard. norv2ge). c. r . acad. sci. paris, 307, 11, 409-414. lepvrier, c . 1990: early tertiary stress history and tectonic development of the forlandsundet basin, svalbard, norway. norsk polarinst. medd. 112, 1-16 lepvrier, c. & geyssant. j . 1985: l'evolution structurale de la marge occidentale du spitsberg: coulissement et rifting tertiaires. bull. soc. geol. france 8 , 115-125. lowell. j . d. 1972: spitsbergen tertiary orogenic belt and the spitsbergen fracture zone. geol. soc. a m . bull. 83, 3091 3102. manby, g. m. 1983: a reappraisal of chloritoid-bearing phyl lites in the forland complex rocks of prins karls forland, spitsbergen. mineral. mag. 47. 31 1-318. o'hara, m. 1967: mineral facies in ultrabasic rocks. pp. 7-18 in wylie. p. j . (ed.): ultra mafic and related rocks. wiley, new york. ohta. y. 1979: blueschists from motalafjella. western spits bergen. norsk polarinst. skr. 167, 171-217. ohta. y. 1982: morpho-tectonic studies around svalbard and the northernmost atlantic. can. soc. petrol. geol. mem. 8 , 415-428. ohta, y . 1988: structure of carboniferous strata at trygghamna and along the se margin of the forlandsundet graben. norsk polarinst. rapp.ser. 46, 25-28. ohta, y . , hiroi, y. &hirajima, t . 1983: additionalevidenceof pre-silurian high-pressure metamorphic rocks in spitsbergen. polar res. i , 215-218. ohta, y., hirajima. t. & hiroi. y . 1986: caledonian high pressure metamorphism in central-western spitsbergen. geol. soc. a m . mem. 164, 205-216. ohta, y., dallmeyer, r. d. & peucat, j . j. 1989: caledonian terranes in svalbard. geol. soc. a m . spec. pap. 230. 1-15. ohta. y.. hjelle. a., andresen. a , , dallmann, w. k. & salvigsen, 0. 1992: geological map svalbard 1 : 1oo,ooo, sheet b9g isfjorden. 52 pp. rye-larsen. m . 1982: forlandsundet graben (paleogene), sval bard. univ. bergen thesis. 380 pp. scrutton, c . t . , horsfield. w. t. & harland, w. b . 1976: silurian fossils from western spitsbergen. geol. mag. 113, 51!+523. steel, r . , gjelberg, j . . helland-hansen, w., kleinspehn, k., ncittvedt. a. and rye-larsen, n . 1985: the tertiary strike slip basins and orogenic belt of spitsbergen. in biddle, k. t . northern continuation of caledonian high-pressure metamorphic rocks 315 and christie-blick. n. (eds.): strike-slip deformation, basin obsfestvo ssr. trudy (panunional mineralogical society of formation and sedimentation. sepm spec. publ. 37, 339the ussr. trudy). pp. 69-83. 359. waddams, p. 1983: the late precambrian succession in north teben’kov, a. m. & korago, e. a.. 1992: osobennosti listvenwest oscar i1 land, spitsbergen. pp. 232-252. itov zapadnogo spicbergena (peculiarities of the olistvenites wilcox, r. e., harding. t . p. & seely, d. r. 1973: basic of west spitsbergen). vsesojuznoe aineralogieesjie wrench tectonics. am. assoc. perrol. geol. bun. 57, 74-96. por_022.fm 118 polar research 26 2007 118 – 125 © 2007 the authors steen et al little auks ( alle alle ) breeding in a high arctic fjord system: bimodal foraging strategies as a response to poor food quality? harald steen 1 , daniel vogedes 2 , fredrik broms 1 , stig falk-petersen 1 & jørgen berge 2 1 norwegian polar institute, polar environmental centre, no-9296 tromsø, norway 2 the university centre in svalbard, po box 156, no-9171 longyearbyen, norway abstract the foraging behaviour of little auks ( alle alle ) in the bjørndalen colony on the western coast of spitsbergen was studied during the breeding season 2005. the duration of foraging trips and contents of gular pouches were analysed. quantitative zooplankton samples procured in the vicinity of the colony facilitated a comparison between gular pouch contents and the availability of prey species. zooplankton and gular pouch samples were all sampled within a time window of approximately one week. using the bray–curtis similarity index, we determined that little auks in this colony have a bimodal foraging strategy consisting of long and short foraging trips with two corresponding distinct diets. short trips are most likely to be centred on areas within the isfjorden complex, whereas the birds are most likely to use the long trips (of typically more than 10 hours) to reach areas off the continental slope where they are able to feed selectively on large, energy-rich food items such as calanus hyperboreus . this bimodal foraging strategy may be a response to the low availability of nutrientrich food close to the colony, which is insufficient to sustain both parents and chicks. bimodal foraging trip strategies are well documented in many species in the southern ocean. this is the first study to show a similar feeding pattern in an alcidae species in the northern hemisphere. keywords alle alle ; breeding; calanus spp.; foraging strategy; svalbard. with more than one million breeding pairs, the little auk ( alle alle ) is one of the most abundant seabirds on spitsbergen (isaksen & gavrilo 2000). little auks have been shown to feed selectively in areas dominated by arctic water masses, where they mainly utilize the largest copepodite stages (cv and adults) of the calanoid copepod species calanus glaciali s (mehlum & gabrielsen 1993; weslawski et al. 1994; weslawski et al. 1999; karnovsky et al. 2003). so far, studies of little auk foraging behaviour have been focused on birds that can choose to feed in either arctic or atlantic water masses, where they can select the energy-rich c. glacialis (mehlum & gabrielsen 1993; weslawski et al. 1994; weslawski et al. 1999; karnovsky et al. 2003). here we present a study of the foraging behaviour, diet and food availability of little auks breeding in a colony by a fjord on the western coast of spitsbergen, which receives a variable influx of warm atlantic water masses (svendsen et al. 2002; berge et al. 2005; cottier et al. 2005), and which harbours the less energetically profitable calanus finmarchicus (falkpetersen et al. 2007). c. finmarchicus is probably too small and has an energetic value too low to sustain a breeding population of little auks (nettleship & evans 1985; weslawski et al. 1999). we studied little auks breeding in the colony at bjørndalen (78 ° 14 ′ n, 15 ° 19 ′ e), which is 50 km from the mouth of isfjorden (fig. 1). little auks arrive at the colony during april, establishing nests in the talus below steep rock faces. a pair lays a single egg in early to midjune; the egg hatches 30 days later. mean fledging is at 25–27 days (stempniewicz 2001; harding et al. 2004). both parents participate in the brooding and feeding of the chick, but the female participates to a lesser degree in the late chick-rearing phase (harding et al. 2004). on their foraging trips little auks store the catch in a gular pouch located below the beak. in the early phase of chick rearing, male and female birds in a colony in hornsund, spitsbergen, engaged in foraging trips that averaged 153 and 148 min in length, respectively (harding et al. 2004). later in the chick-rearing period these values increased to correspondence harald steen, norwegian polar institute, polar environmental centre, no-9296 tromsø, norway. e-mail: harald.steen@npolar.no. doi:10.1111/j.1751-8369.2007.00022.x h. steen et al. little auks ( alle alle ) breeding in a high arctic fjord system polar research 26 2007 118 – 125 © 2007 the authors 119 155 min for males and 375 min for females, few of which delivered food to their chicks (harding et al. 2004). the chicks require 262 kj/day to grow normally, and this is estimated to be equivalent to four food loads per parent each day (karnovsky et al. 2003; kwasniewski et al. 2003). isfjorden is an open fjord on the western coast of spitsbergen (fig. 1) that is periodically strongly influenced by the influx of warmer atlantic water masses (berge et al. 2005; cottier et al. 2005; svendsen et al. 2002). as a result of the gradual modification of the vertical stratification in the fjord through mixing with warmer and fresher surface water, the front separating fjord and shelf water weakens and allows atlantic water to penetrate into the fjord (cottier et al. 2005). episodic and rapid intrusion of atlantic water can also appear in the autumn during periods with prevailing northerly winds, as a result of offshore eckmann transport in the surface layer compensated by onshore subsurface transport of atlantic water masses into the fjord (berge et al. 2005). in effect, the fjord is mainly dominated by arctic water during the winter, whereas there are large annual variations in the influx of warmer atlantic water during summer. predictable cold water masses are most prevalent in sill fjords where the sill effectively prevents mixing of water masses. as a result of the dominance of arctic water masses and the presence of a sill, billefjorden (40–55 km from the bjørndalen colony) has been shown to retain a relatively large and stable population of the arctic species c. glacialis (arnkværn et al. 2005). in isfjorden itself (figs. 1, 2; stations d3–d7), which is regularly influenced by warmer atlantic water masses, the same reliable standing stock of large and energy-rich food resources is not to be expected. the shelf brake, offering another rich feeding ground (falk-petersen et al. 2007) is approximately 150 km away and is probably too far for frequent regular foraging trips. little auks breeding in bjørndalen may be faced with low availability of preferred prey close to the colony, and abundant, energy-rich, preferred prey further away. faced with the same spatial distribution of prey, blue petrels ( halobaena caerulea ) in the southern ocean have a bimodal foraging trip pattern in which, it is hypothesized, food for chicks is procured on short trips, whereas longer trips are used for energetic self-maintenance (weimerskirch et al. 2003). given the poor foraging opportunities close to the bjørndalen colony, we predict that little auks there have developed a similar bimodal foraging behaviour. material and methods zooplankton—net tows zooplankton were collected along a transect spanning the entire length of isfjorden (fig. 1) with two consecutive replicate standard wp-2 plankton net hauls (0.25 m 2 in area, mesh size 180 µ m) at each of the four stations on 27 july 2005. as little auks only dive to 35 m (falk et al. 2000) the nets were towed vertically from a depth of 50 m up to the surface. attached to the nets was a salinity–temperature–depth (std) unit (sd 204; saiv a/s, bergen, norway) that measured the depth-specific temperature and salinity at each station. the sampling interval on the std was set to 1 s − 1 . zooplankton samples were preserved in a 4% borax-buffered formaldehyde seawater fig. 1 (a) svalbard and (b) isfjorden, showing the sampling sites (d1–d7) along the isfjorden transect. the star indicates the location of the bjørndalen little auk colony. 120 polar research 26 2007 118 – 125 © 2007 the authors little auks ( alle alle ) breeding in a high arctic fjord system h. steen et al. solution. in the laboratory, samples were split using a simple box splitter down to fractions containing approximately 250 copepodites of calanus spp. based on these fractions, all calanus specimens from copepodite stage (c1) to adult females (af) were measured and identified on the basis of their prosome lengths, using size distribution tables that are well established for svalbard waters (kwasniewski et al. 2003). a zeiss stereomicroscope was used for identification and counting. a 100% filtering efficiency of the wp-2 net was assumed, and the sampled seawater volume was calculated based on the wire length and the net opening area. densities of the different calanus stages are presented as the average between the two replicates (fig. 3). foraging trip duration little auks were caught using a 9-m mist net placed perpendicular to the talus slope at the bottom of the study area. birds caught in the net were immediately removed and all birds received three colour rings for later identification using binoculars. we also injected an 11 × 2 mm id 100a passive integrated transponder (pit) tag (eid aalten bv, aalten, the netherlands) subcutaneously in the back of each bird’s neck to be able to study their feeding behaviour. using binoculars, we were able to find the probable nest entry holes of 10 nests. we equipped the 10 nest entry holes with tube-shaped pit tag antennas that were hooked up to a trovan® lid665 oem pittag decoder (eid aalten bv; see korslund & steen 2006 for details). all other entrances were blocked. each time a bird with a pit tag passed through the antenna the time of passage and the bird’s unique identification number was stored in the reader. using this procedure we got reliable readings from four birds, two from the same entrance hole, between 23 july and 4 august 2005. all fig. 2 (a) salinity and (b) temperature profiles of isfjorden on 27 july 2005. the four sampling stations are indicated at the top. temperature and salinity plots were produced using the 1d interpolation function “interp1” of the m atlab (v. 7.0.1; mathworks inc., natick, ma, usa) software package, based on the four bottom-to-surface conductivity-temperature-depth casts. a rough outline of the bottom topography is represented in black. fig. 3 stage-specific abundance (calculated as number of individuals per m 3 ) of the three species calanus hyperboreus , c. glacialis and c. finmarchicus at the four stations (d1, d3, d5 and d7) spanning the entire length of isfjorden (see fig. 1). samples were taken on 27 july 2005. scales on the x -axis differ in order to highlight the stageand species-specific variations along the transect. h. steen et al. little auks ( alle alle ) breeding in a high arctic fjord system polar research 26 2007 118 – 125 © 2007 the authors 121 summary statistics were calculated using raw trip time data from all four birds. trips shorter than 10 min were regarded as movements around the nest entrance and were not used in the calculation of foraging trip times. using the times between two passages through the pit tag antenna would give time spent either in the burrow or outside it. the time series with the longest times is probably time spent outside the burrow, as the chicks are homeothermic at 2–4 days (harris & birkehead 1985) and the study was undertaken late in the breeding season (see results for details). zooplankton—gular pouches diet samples from the little auks were taken from 24 birds caught in the mist net in the study area. the contents of the gular pouches were carefully scooped out using a blunt spoon (three in late june and 21 between 21 and 23 july 2005). although all visible prey items were removed from the gular pouches, we are not certain that the samples contain all food items the bird brought back to the colony. hence, no quantitative conclusions can be drawn regarding total biomass of prey items in each food load. however, as the gular pouches were sampled without any bias towards specific prey items, relative frequencies of occurrence were calculated based on the raw data. a summary is presented in table 1. the contents of the gular pouches were immediately transferred to small plastic beakers containing 70% ethanol and/or 4% borax-buffered formaldehyde seawater solution for preservation and later analysis. in the laboratory, the contents of the gular pouches were analysed in the same way as the net tow samples described above. the relative similarity of gular pouch contents was compared using the bray– curtis similarity index (bray & curtis 1957) and was displayed using the primer software package. we used the square roots of the absolute numbers of each prey species in each of the gular pouch samples as variables to minimize the effect of large numbers and zeros. results zooplankton along the isfjorden transect two replicates of the four stations along the isfjorden transect (except station d6, for which only a single sample was available) were analysed (fig. 3). the absolute number of calanus spp. was highest at the innermost station (d1), whereas the relative frequencies of c. glacialis and c. finmarchicus remained approximately the same along the three inner stations, with roughly twice as many c. glacialis as c. finmarchicus . at all but the innermost station, copepodite stage civ was present in higher numbers than all other stages. the abundance of the largest copepodite stages of calanus hyperboreus was very low along the transect, with a total of four specimens (civ, cv and af) encountered in all samples combined. according to the std profiles along the same transect, the density front at the mouth of the fjord system had not yet broken down, and most of the fjord was still dominated by relatively cold arctic water masses (berge et al. 2005; cottier et al. 2005). in the upper layers, however, freshwater run-off was locally dominant (fig. 2), with possibly a marked impact on the small-scale distribution and abundance of the zooplankton. foraging trip times the little auks showed a striking and repetitive pattern in their feeding trips, with a series of short trips followed by table 1 frequency of occurrence of different prey species in gular pouch contents from 24 little auks. diets with 25% c. hyperboreus or less a diets with more than 25% c. hyperboreus a species mean se mean se amphipoda sp. 0.001 0.001 0.000 0.000 apherusa glacialis 0.000 0.000 0.003 0.002 bivalvia larvae 0.004 0.004 0.000 0.000 calanus finmarchicu s ciii 0.000 0.000 0.000 0.000 calanus finmarchicus civ 0.002 0.002 0.004 0.004 calanus finmarchicus cv 0.051 0.018 0.004 0.004 calanus finmarchicus af 0.004 0.001 0.000 0.000 calanus glacialis ciii 0.000 0.000 0.000 0.000 calanus glacialis civ 0.006 0.002 0.007 0.007 calanus glacialis cv 0.571 0.056 0.144 0.019 calanus glacialis af 0.018 0.002 0.008 0.004 calanus hyperboreus civ 0.003 0.002 0.018 0.008 calanus hyperboreus cv 0.014 0.008 0.407 0.035 calanus hyperboreus af 0.007 0.003 0.286 0.052 calanus sp. 0.052 0.010 0.080 0.022 themisto abyssorum 0.176 0.048 0.029 0.021 themisto libellulla 0.009 0.005 0.001 0.001 themisto sp. 0.015 0.004 0.008 0.002 thysanoessa furcilia 0.002 0.001 0.000 0.000 thysanoessa longicaudata 0.032 0.010 0.001 0.001 thysanoessa rachii 0.000 0.000 0.002 0.002 thysanoessa sp. 0.019 0.004 0.002 0.002 zoea larvae 0.005 0.003 0.002 0.002 other b 0.009 0.002 0.006 0.004 a we have divided the data into two diet groups based on the similarity indexes: one group containing 25% or less calanus hyperboreus ( n = 19) and one group containing more than 25% c. hyperboreus ( n = 5). the numbers in boldface indicate prey items that occur in 10% or more of the gular pouches. b the category ‘other’ consists of fish larvae, gammarus setosus , gammarus wilkitzkii , hyperoche medusarum , ischyrocerus anguipes , metridia longa civ, metridia longa female, onisimus litoralis , onisimus sp., ostracoda, pareuchaeta sp., sagitta elegans and unidentified mollusca. 122 polar research 26 2007 118 – 125 © 2007 the authors little auks ( alle alle ) breeding in a high arctic fjord system h. steen et al. one long trip (fig. 4). we obtained continuous registration of foraging trip times of birds from three nests (20, 25 and 35) from 23 july to 3 august 2005. both parents at nest 20 were registered, but only one gave high-quality registrations; data from the bird with low-quality registrations are not shown in fig. 4. the chick in nest 25 hatched on 11 july, followed by chicks hatching in nest 35 on 17 july and in nest 20 on 18 july. the youngest chick was 5 days old at the start of the study and was already thermoregulatorily independent of its parents (harris & birkehead 1985). trips shorter than 10 min constituted 54 and 27% of the movements of both parents in nest 20, whereas they constituted 69 and 60% of the movements of birds in nests 25 and 35, respectively. the remaining trips showed a poisson distribution pattern with an average of 89 (se 3.4) min/trip when considering only trips shorter than 5 h, and an average of 675 (se 43.1) min/trip when considering only trips longer than 5 h. if we use a cut-off point of 5 h we get a ratio of 5.15 short trips ( ≤ 5 h) to one long trip ( > 5 h) fig. 4 duration of foraging trips and time spent in the nest of parents from three nests (20, 25 and 35). foraging trips are positive values and time in the nest are negative values. the height of each bar indicates time spent on a particular trip and the x -axis denotes the start and stop time of the trip. h. steen et al. little auks ( alle alle ) breeding in a high arctic fjord system polar research 26 2007 118 – 125 © 2007 the authors 123 using data from all trips and birds. we used 5 h as a cutoff because this duration was longer than the bulk of the short trips. chick diet gular pouch contents from 24 little auks were analysed and identified. in total, the average number of prey items in the gular pouches was 460 (se 53.3), ranging from a minimum of 54 items up to 962 (except for one sample, diet sample #10, that contained approximately 2000 unidentified eggs). among these, calanus spp. were the dominant group of food items, although thysanoessa spp. and themisto abyssorum were also frequent (table 1). using the bray–curtis similarity index (bray & curtis 1957), we determined that the diet of the little auks was characterized by a group of five samples containing 25% or more c. hyperboreus (14, 17, 20, 22 and 24), and another group with either no or less c. hyperboreus (table 1, fig. 5). this separation into two diet groups is interesting as c. hyperboreus was hardly found in our net hauls in isfjorden, and probably originates from outside the fjord (falk-petersen et al. 2007). among the calanus species, c. glacialis was the dominant species and, interestingly, cv stages were recorded nearly exclusively in the gular pouch samples. only a few c. glacialis civ were recorded, whereas there was a consistently low number of af in most of the gular pouches. the birds that had high numbers of c. hyperboreus also had high numbers of c. glacialis . low numbers of c. finmarchicus were recorded in most gular pouches. there also seemed to be a consistent pattern in that those gular pouches with low to medium numbers of c. glacialis and very few c. hyperboreus had the largest number of t. abysorum and krill, mainly thysanoessa longicaudata (table 1). trip times and diet as shown above, analysing the pit tag data revealed that little auks have short and long foraging trips at a ratio of 5.15 : 1. if the 24 gular pouch samples are taken to represent 24 trips, and if we apply the ratio of 5.15 : 1 to these 24 trips, we would expect 3.9 long trips and 20.1 short trips. assuming that a sizeable quantity of c. hyperboreus in the gular pouch indicates that the bird has been feeding outside the isfjorden complex, and hence has been on a ‘long’ foraging trip, the ratio between short and long trips based on diet is 3.8 short trips to 1 long foraging trip (19 short trips and 5 long trips). the similarity in the ratio of short and long trips from the pit tag data to the ratio of the gular pouches having less than and more than 25% c. hyperboreus is striking, and is not significantly different (fisher’s exact test, p > 0.9). if we lower the cut-off point and use 5% c. hyperboreus instead of 25% as the dividing line between short and long trips, as deduced from the gular pouch contents, there were 16 short trips and 8 long trips—a ratio of 2 : 1, which is still not significantly different from the expected ratio based on the gular pouch samples (p > 0.3). discussion five of the 24 gular pouch contents from little auks breeding in bjørndalen, spitsbergen, contained large fig. 5 cluster diagram based on the bray– curtis similarity index, and produced with a group average linkage between the clusters. the gular pouches are divided into two major clades, one consisting of samples 14, 17, 20, 22 and 24 (outlined in the box) and one consisting of the remaining samples. samples 14, 17, 20, 22 and 24 contain more than 50% calanus hyperboreus. 124 polar research 26 2007 118 – 125 © 2007 the authors little auks (alle alle) breeding in a high arctic fjord system h. steen et al. quantities of c. hyperboreus, suggesting that the birds catch prey at two distinct locations. during long trips, averaging 11.5 hours, the little auks probably forage on the preferred prey c. hyperboreus (pedersen & falk 2001) at the shelf brake, about 150 km away from the colony. the short trips, on average 1.5 hours, are limited to the area close to the breeding colony, where they feed on c. glacialis (table 1, fig. 4). calanus species have a 2–5-year life cycle in the arctic (falk-petersen et al. 2007). the energy needed for surviving the dark, unproductive polar night is collected during the productive part of the year, and is stored as lipids in oil sacs. the older stages of calanus species contain oil sacs that can fill up most of the body cavity. the oil sac grows 2.8 times when the prosome length increases from 2.5 to 3.5 mm within the same calanus species (vogedes et al. unpubl. data). the size and energy content differ markedly between the species as well as between the stages (scott et al. 2000; falk-petersen et al. 2007). for example, c. glacialis and c. hyperboreus are considerably larger than c. finmarchicus, and stage cv c. glacialis and c. hyperboreus contain approximately 10 and 25 times more energy (lipids) per individual, respectively, than c. finmarchicus. the little auks in our study area seem to select nearly exclusively c. glacialis stage cv, although c. glacialis stage civ are much more abundant at all stations except the station at the bottom of billefjorden (d1). what is even more striking is that a substantial quantity of af c. glacialis was found in the gular pouches, even though not a single af was recorded in the net hauls. five birds had high numbers of c. hyperboreus (civ, cv, af); these five birds also had moderate to high numbers of c. glacialis stages cv and af. along the transect that spanned the entire isfjorden, only four c. hyperboreus individuals were recorded in the net hauls. c. finmarchicus was only recorded in low number in gular pouches despite its abundance in the fjord. from this we can deduce that the little auk is able to select two very specific zooplankters: the larger stages of c. glacialis and c. hyperboreus (mainly stage cv for both species). although c. glacialis is common all over isfjorden, c. hyperboreus is only found in significant numbers at the shelf break, approximately 150 km away from the nests (falk-petersen, pers. comm.). the higher energy demand for carrying out long foraging trips may be outweighed by the significantly higher energy content of c. hyperboreus. the cooccurrence of the highest number of c. hyperboreus and c. glacialis stage cv and af in five of the birds suggest that these species occur together in dense concentrations on the shelf brake or the outer shelf. for the shorter trips within isfjorden, the little auk probably feed on c. glacialis, t. abysorum and krill, which are known to be abundant in west spitsbergen fjords (hop et al. 2002; kwasniewski et al. 2003). conclusion we show for the first time a bimodal foraging trip pattern (granadeiro et al. 1998; weimerskirch et al. 2003) for an alcid species. this bimodal pattern is likely to be caused by a lack of suitable prey items close to the colony, forcing breeding little auks to also forage in distant areas. the long foraging trips are too infrequent to provide enough energy for the chicks (karnovsky et al. 2003; kwasniewski et al. 2003). thus, our results support the hypothesis that the long foraging trips are likely to have evolved in order to replenish energy reserves for the adults, whereas the short trips mainly provide food for the chicks (granadeiro et al. 1998; weimerskirch et al. 2003). a flexible foraging strategy might have evolved in response to a highly variable environment, and further studies should focus on breeding performance relative to the ratio of short and long foraging trips. in good years, long trips should be short and more time should be spent on short foraging trips. in poor years the long trips should be longer, and there should be fewer short trips. breeding performance should be negatively correlated to the average long trip length. acknowledgements the study was financed by the norwegian seabird monitoring project seapop, the norwegian polar institute and the university centre in svalbard. we thank r. lagnes, m. ritman and l. korslund for help in the field, as well as k. falk and two anonymous referees for improving the manuscript. references arnkværn g., daase m. & eiane k. 2005. dynamics of coexisting calanus finmarchicus, calanus glacialis and calanus hyperboreus populations in a high-arctic fjord. polar biology 28, 528–538. berge j., johnsen g., nilsen f., gulliksen b. & slagstad d. 2005. ocean temperature oscillations enable reappearance of blue mussels mytilus edulis in svalbard after 1000 year absence. marine ecology progress series 303, 167–175. bray j.r. & curtis j.t. 1957. an ordination of the upland forest communities of southern wisconsin. ecological monographs 27, 325–349. cottier f., tverberg v., inall m., svendsen h., nilsen f. & griffiths c. 2005. water mass modification in an arctic fjord through cross-shelf exchange: the seasonal hydrology of kongsfjorden, svalbard. journal of geophysical research, oceans 110, doi 10.1029/2004jc002757. h. steen et al. little auks (alle alle) breeding in a high arctic fjord system polar research 26 2007 118 – 125 © 2007 the authors 125 falk k., pedersen c.e. & kampp k. 2000. measurements of diving depth in dovekies (alle alle). auk 117, 522–525. falk-petersen s., timofeev s., pavlov v. & sargent j.r. (eds.) 2007. climate variability and the effect on arctic food chains. the role of calanus. berlin: springer verlag. granadeiro j.p., nunes m., silva m.c. & furness r.w. 1998. flexible foraging strategy of cory’s shearwater, calonectris diomedea, during the chick-rearing period. animal behaviour 56, 1169–1176. harding a.m.a., van pelt t.i., lifjeld j.t. & mehlum f. 2004. sex differences in little auk alle alle parental care: transition from biparental to paternal-only care. ibis 146, 642–651. harris m.p. & birkehead t.r. 1985. breeding ecology of the atlantic alcidae. in d.n. nettleship & t.r. birkehead (eds.): the atlantic alcidae. pp. 155–204. london: academic press. hop h., pearson t., hegseth e.n., kovacs k.m., wiencke c., kwasniewski s., eiane k., mehlum f., gulliksen b., wlodarska-kowalezuk m., lydersen c., weslawski j.m., cochrane s., gabrielsen g.w., leakey r.j.g., lonne o.j., zajaczkowski m., falk-petersen s., kendall m., wangberg s.a., bischof k., voronkov a.y., kovaltchouk n.a., wiktor j., poltermann m., di prisco g., papucci c. & gerland s. 2002. the marine ecosystem of kongsfjorden, svalbard. polar research 21, 167–208. isaksen k. & gavrilo m. 2000. little auk. in t. anker-nilssen et al. (eds.): the status of marine birds breeding in the barents sea region. norsk polarinstitutt rapportserie 113. karnovsky n.j., kwasniewski s., weslawski j.m., walkusz,w. & beszczynska-moller a. 2003. foraging behavior of little auks in a heterogeneous environment. marine ecology progress series 253, 289–303. korslund, l. & steen, h. 2006. small rodent winter survival: snow conditions limit access to food resources. journal of animal ecology 75, 156–166. kwasniewski s., hop h., falk-petersen s. & pedersen g. 2003. distribution of calanus species in kongsfjorden, a glacial fjord in svalbard. journal of plankton research 25, 1–20. mehlum f. & gabrielsen g.w. 1993. the diet of high-arctic seabirds in coastal and ice-covered, pelagic areas near the svalbard archipelago. polar research 12, 1–20. nettleship d.n. & evans p.g.h. 1985. distribution and status of the atlantic alcidae. in d.n. nettleship & t.r. birkehead (eds.): the atlantic alcidae. pp. 53–154. london: academic press. pedersen c.e. & falk k. 2001. chick diet of dovekies alle alle in northwest greenland. polar biology 24, 53–58. scott c.l., kwasniewski s., falk-petersen s. & sargent j.r. 2000. lipids and life strategies of calanus finmarchicus, calanus glacialis and calanus hyperboreus in late autumn, kongsfjorden, svalbard. polar biology 23, 510–516. stempniewicz l. 2001. little auk alle alle. bwp update. the journal of birds of the western palearctic 3, 175–201. svendsen h., beszczynska-møller a., hagen j.o., lefauconnier b., tverberg v., gerland s., ørbæk j.b., bischof k., papucci c., zajaczkowski m., azzolini r., bruland o., wiencke c., winther j.-g. & dallmann w. 2002. the physical environment of kongsfjorden–krossfjorden, an arctic fjord system in svalbard. polar research 21, 133–166. weimerskirch h., ancel a., caloin m., zahariev a., spagiari j., kersten m. & chastel o. 2003. foraging efficiency and adjustment of energy expenditure in a pelagic seabird provisioning its chick. journal of animal ecology 72, 500–508. weslawski j.m., stempniewicz l. & galaktionov k. 1994. summer diet of seabirds from the franz-josef-land archipelago, russian arctic. polar research 13, 173–181. weslawski j.m., stempniewicz l., mehlum f. & kwasniewski s. 1999. summer feeding strategy of the little auk (alle alle) from bjornoya, barents sea. polar biology 21, 129–134. por_023.fm 168 polar research 26 2007 168 – 174 © 2007 the authors mussen & j. kohler mass balance of three svalbard glaciers reconstructed back to 1948 l. a. rasmussen 1 & j. kohler 2 1 department of earth and space sciences, university of washington, seattle, wa 98195, usa 2 norwegian polar institute, polar environmental centre, no-9296 tromsø, norway abstract a simple model using upper-air meteorological variables in the ncep-ncar reanalysis database is used to model seasonal components of mass balance of three glaciers in svalbard. the model was originally developed for glaciers in north america, and has been applied to glaciers in norway, sweden and iceland. over the period for which mass balance data are available for the three svalbard glaciers, the model fit yields r 2 values ranging from 0.46 to 0.61 for winter balance b w and from 0.56 to 0.59 for summer balance b s . sensitivity to + 1 ° c warming was about − 0.36 m yr − 1 water equivalent (w.eq.), caused mainly by increased ablation and secondarily by shift of precipitation from snow to rain. sensitivity to a 10% increase in precipitation was about + 0.06 m yr − 1 w.eq. the model, calibrated over the period of observations, was used to extend the mass balance series back to 1948. at annual resolution, observed mass balance of the three glaciers correlates poorly with both the north atlantic oscillation (nao) and with glaciers in norway. over two multiyear periods, the strongly positive nao period 1990–1996 and the period afterward, glaciers in both svalbard and especially norway showed a pronounced decline in b w . however, b s for svalbard glaciers was not more strongly negative after 1996, in contrast to glaciers in norway. keywords glacier mass balance; svalbard; upper air model; ncep-ncar re-analysis. glacier volume changes fundamentally in response to climate change. glacier volume changes over long timescales amount to changes in glacier thickness or, equivalently, in the surface elevation, and can be studied using comparison of maps or digital elevation models. on shorter timescales, mass balance measurements are used to characterize changes. glacier mass balance is the quantity of snow and ice either lost or gained on a particular glacier, and represents the material flux through the glacier surface over an interval of time. although volume change estimates for glaciers arguably go as far back as the 1700s, in the form of front position measurements (oerlemans 2001), the longest continuous annual mass balance measurements only date back to the 1940s. the latter are for glaciers in scandinavia; in the arctic, mass balance time series are even shorter, only going back to the early 1960s. the three glaciers considered in this paper, austre brøggerbreen, midre lovénbreen and kongsvegen in western svalbard (fig. 1) have some of the longest time series (1967– present, 1968–present and 1987–present, respectively) in the high arctic. a detailed description of the glaciers can be found in lefauconnier et al. (1999). previous workers have sought to extend the mass balance record for these glaciers. hagen & leistol (1990) used meteorological measurements at ny-ålesund in a positive degree day (pdd) model of summer balance b s at midre lovénbreen. lefauconnier & hagen (1990) used multivariable linear regression between ny-ålesund observations and austre brøggerbreen net or annual mass balance b n . dewoul & hock (2005) applied a pdd model of ablation, using daily observations of temperature at ny-ålesund, and linear regression between precipitation observations there and accumulation for each of the three glaciers. in this paper we extend the mass balance using a simple model driven by upper-air meteorological variables in the ncep-ncar reanalysis database. the database has the advantage that it is global in extent, has 6-h temporal resolution, is free from missing observations and is main correspondence l.a. rasmussen, department of earth and space sciences, university of washington, seattle, wa, 98195, usa. e-mail: lar@ess.washington.edu. doi:10.1111/j.1751-8369.2007.00023.x l. a. rasmussen & j. kohler three svalbard glaciers reconstructed back to 1948 polar research 26 2007 168 – 174 © 2007 the authors 169 tained as an integral part of a major scientific enterprise. the model was developed with data from south cascade glacier (48.4 ° n, 121.1 ° w): first for winter balance b w (rasmussen & conway 2001) and then for b s (rasmussen & conway 2003). it was successfully applied to glaciers in alaska (rasmussen & conway 2004), scandinavia (rasmussen & conway 2005) and iceland (rasmussen 2005). data us national centers for environmental prediction and us national center for atmospheric research (ncep-ncar) reanalysis data (kalnay et al. 1996; kistler et al. 2001) give values of meteorological variables at many levels in the atmosphere at 10 512 gridpoints spanning the entire globe, at integral multiples of 2.5 ° in both latitude and longitude. data for 1948–2005 at the 1000and 850-hpa levels were downloaded from east anglia university, uk (http://www.cru.uea.ac.uk/cru/data/ncep). variation of mean september–may upper-air variables with wind direction at the reanalysis gridpoint (77.5 ° n, 12.5 ° e; fig. 1) is shown in fig. 2. their seasonal variation is shown in fig. 3, along with the precipitation flux f and snow flux f (eqns 1–3) calculated from direction φ ′ = 210 ° . both figures show that f is strongest when the wind is from the south-west. the glacier mass balance data used are winter, summer and net balances b i , where i = winter, summer and net for the years 1967–2005 (austre brøggerbreen), 1968–2005 (midre lovénbreen) and 1987–2005 (kongsvegen) (hagen et al. 2003; kohler, unpubl. data). standard deviations of the seasonal balance components are shown in table 1. the correlations r ns of b n with b s are larger than fig. 1 map showing the three study glaciers: austre brøggerbreen (a), midre lovénbreen (m) and kongsvegen (k). upper-air conditions are taken at the ncep-ncar reanalysis gridpoint nearest the glaciers at 77.5 ° n, 12.5 ° e (filled circle). k m a 10º 20º svalbard 30º 77º 79º 5 km n fig. 2 variation with wind direction of mean september–may conditions over the period 1948–2005 at the ncep-ncar reanalysis gridpoint (77.5 ° n, 12.5 ° e): (a) relative humidity rh, (b) temperature t , (c) wind speed and snow flux and (d) frequency distribution of wind direction. rh and wind are at 850 hpa; t and are at 200 m. 90 180 2700 360 wind direction relative frequency (d) wind speed snow flux 6 8 10 m s -1 (c) -10 -5 c temperature (b) 70 80 relative humidityp e rc e n ta g e (a) fw fw http://www.cru.uea.ac.uk/cru/data/ncep 170 polar research 26 2007 168 – 174 © 2007 the authors three svalbard glaciers reconstructed back to 1948 l. a. rasmussen & j. kohler r nw ( b n with b w ), in rough proportion to the amount by which σ s is larger than σ w , because the correlation r ws between b w and b s is so small (see eqn 13 of rasmussen & conway 2001). the r ws are small, as is the case for glaciers elsewhere in the world (see fig. 6 of dyurgerov & meier 1999; and fig. 5 of braithwaite & zhang 1999). glacier to glacier correlation of b s and of b w are both coherent spatially (table 2). recent variations although mass balance at the three svalbard glaciers correlates poorly with the mass balance at glaciers in northern and maritime norway (rasmussen, in press), they do share some longer-term characteristics. correlations of b n and b s between the two regions are positive but small. correlations of b, and of b 3 between the two regions are positive but small, and those of b w are negative but small. the only exceptions are r ( b n ) = 0.69 between kongsvegen and langfjordjøkelen (70.1 ° n, 21.8 ° e) and 0.47 < r ( b s ) < 0.50 for the three glaciers with engabreen (66.6 ° n, 13.8 ° e). correlation with three different measures of the north atlantic oscillation (nao) that are significant at annual resolution for glaciers in norway with r ( b n ) > 0 and r ( b w ) > 0 are negligible for all three glaciers in svalbard. low correlation with the nao was also found by pohjola & rogers (1997), nesje et al. (2000) and washington et al. (2000). there were some similar changes in the two regions, however, over multiyear periods in phase with the nao regime. at ten glaciers in norway the mean change in the mass balance components δ b i (in units of m w.eq.) obtained from comparing the strong nao period 1990–1996 with the following period 1997–2004 was δ b n ≈ –1.0, consisting of changes δ b w ≈ –0.4 and δ b s ≈ –0.6 (andreassen et al. 2005). at the glaciers in svalbard, changes between 1990–1996 and 1997–2005 were − 0.29 < δ b w < –0.18, all significant at 99%, but changes in summer balance − 0.13 < δ b s < + 0.03 were weaker. upper-air model precipitation at the glacier is assumed to be proportional to the precipitation flux f at the 850-hpa level. it is estimated from measurements of wind and humidity by the relation (1)f u u = ≥( ) ( )    rh otherwise 0 0 . fig. 3 seasonal variation of mean conditions over the period 1948–2005 at the ncep-ncar reanalysis gridpoint (77.5 ° n, 12.5 ° e). (a) wind direction at 850 hpa, (b) wind speed at 850 hpa, (c) temperature t interpolated at 200 m, (d) percentage relative humidity rh at 850 hpa and (e) precipitation flux f calculated from eqns (1) and (2) using φ′ = 210° and snow flux f, the part of f when t < +2°c at 200 m. monthly resolution. jan mar may jul sep nov 240 260 280 300 wind direction d e g re e s (a) 1 2 wind speed (b) -10 -5 0 temperature c (c) 72 76 80 relative humidity p e rc e n ta g e (d) 1 2 3 precipitation snow (e) m s -1 m s -1 table 1 mean and standard deviation (both in m water equivalent [m w.eq.]) and correlation (percentage r) of seasonal mass balance components over the period of record of observations (n years). all rnw and rns are significant at 99%. glacier °n °e n σw σs rnw rns rws austre brøggerbreen 78.9 11.8 39 0.67 −1.16 0.15 0.30 43 89 −3 midre lovénbreen 78.9 12.1 38 0.70 −1.09 0.17 0.29 40 84 −16 kongsvegen 78.8 13.0 19 0.71 −0.79 0.19 0.28 74 89 36 bw bs table 2 glacier to glacier correlation (percentage r, significant at 99%) of winter balance bw (above the diagonal) and summer balance bs (below the diagonal) over the common period of observations. values on the diagonal are for both bw and bs. glacier 1 2 3 1 austre brøggerbreen 100 94 76 2 midre lovénbreen 96 100 80 3 kongsvegen 90 84 100 l. a. rasmussen & j. kohler three svalbard glaciers reconstructed back to 1948 polar research 26 2007 168 – 174 © 2007 the authors 171 here, 0 ≤ rh ≤ 1 is the relative humidity, and u is the component of the 850-hpa wind in the empirically determined critical direction φ′. that is, (2) in which φ850 is the wind direction and is its speed in ms−1. although precipitation indeed might occur with the wind in the opposite direction to φ′, empirical results show it correlates most strongly with the u component. moreover, the simple model described here obtained better results (hayes et al. 2002) in a direct comparison with a sophisticated mesoscale precipitation model. precipitation is assumed to fall as snow if the temperature at elevation z1 = 200 m is less than the critical temperature t ′ (3) here f is termed the snow flux, t(z1) is interpolated between the 1000and 850-hpa levels in the ncepncar reanalysis data, and t ′ = +2°c is the rain–snow discriminator (oerlemans 1993; rasmussen et al. 2000; forland & hanssen-bauer 2003; kohler & aanes 2004). the physical basis for using +2°c as the discriminator is that precipitation forming at high altitude as snow requires a layer of air with t > 0°c to change to rain; at the average wet adiabatic lapse rate of −6°c km−1, +2°c corresponds to a layer thickness of ≈300 m. the model estimates winter balance by (4) coefficients αw and βw are obtained by linear regression of observed winter balance bw and , which is the september–may average of f. because rh is dimensionless, both f and f have the same units as u (ms−1), so αw has units to convert to m w.eq. the quantity αw corresponds most closely to actual snowfall, but is higher by about a factor of two than the september–may precipitation measured at ny-ålesund, which might reflect either higher precipitation on the glaciers caused by orographic lifting or undercatch in the precipitation gage (e.g. forland & hanssen-bauer 2000). u v= − ′( ) r 850 850cos f f , r v850 f f t z t = ( ) ≤ ′( ) ( )    1 0 otherwise . bw* b* fw w w w= +α β f w f w the model estimates summer balance by (5) in which is the june–august average of temperature interpolated at altitude z2 = 500 m between the 1000and 850-hpa levels, considering only t ′ > t ″, where t ″ is the degree-day temperature threshold, here taken to equal 0°c. coefficients αs and βs are obtained by linear regression of the observed summer balance bs with . both and are estimated from upper-air conditions at the ncep-ncar reanalysis gridpoint 77.5° n, 12.5° e. mean winter conditions for the period 1948– 2005 are shown in fig. 2. the only model parameter that was varied experimentally to optimize the model results was the critical direction φ′ (table 3). all the other parameters, the altitudes z1 = 200 m and z2 = 500 m, the critical temperatures t′ = +2°c and t″ = 0°c, and the seasons september–may and june–august, were held constant. for each glacier, model parameters α and β were determined by the regressions of eqns (4) and (5) fitted to the observed b. for all three glaciers βw ≈ 0.05 so that α accounts for almost all of . model results model estimates of seasonal components, both of which are identified by the calendar year in which the balance year ends, are illustrated in fig. 4. as pointed out by von storch (1999), the variance of regression results is smaller than that of the variable being fitted (unless the regression fits it exactly). goodness of fit (bevington 1969) is expressed by the coefficient of determination (6) here, rms is the root mean square of the differences between the model estimates b* and the measured values b, and σ is the standard deviation of b. results are shown in table 3. they are generally much better for bw and slightly worse for bs compared with those obtained by dewoul & hock (2005). bs* b* t ,s s s= +α β t t b*w b*s f w b*w r 2 2 1= −     rms s . table 3 model results (percentage r2 and m water equivalent [m w.eq.], per year rms) over the period of record using critical direction φ′ with upper-air model and and from dewoul & hock (2005). models: (1) upper-air model, (2) correlation with austre brøggerbreen, (3) average of models (1) and (2). glacier model φ′ rmsw rmsn rmss austre brøggerbreen 1 210 49 55 56 0.11 0.23 0.20 <15 61 midre lovénbreen 1 210 46 52 56 0.12 0.21 0.19 <15 76 kongsvegen 1 235 61 68 59 0.12 0.22 0.18 67 68 kongsvegen 2 58 80 80 0.13 0.18 0.13 kongsvegen 3 67 80 77 0.11 0.17 0.14 r̂w 2 r̂s 2 rw 2 rn 2 rs 2 r̂w 2 r̂s 2 172 polar research 26 2007 168 – 174 © 2007 the authors three svalbard glaciers reconstructed back to 1948 l. a. rasmussen & j. kohler hagen & leistøl (1990) obtained linear relations between lovénbreen bs and ny-ålesund meteorological observations with r = 0.75 for june–august temperature and r = 0.88 for june–september pdd. lefauconnier & hagen (1990) used multivariable linear regression to relate brøggerbreen bn to ny-ålesund observations, obtaining r 2 = 0.77 with july–august pdd and october– may precipitation, whereas with pdd taken separately for four individual summer periods, r 2 increased to 0.81. our model results are only weakly sensitive to values of model parameters z1 and z2 as well as to the period of days over which averages are formed. if the period of forming is extended into june, for instance, it will be lower because f decreases in june (fig. 3); in the regression of eqn (4), however, the coefficient αw will tend to increase so as to match the observed bw as well as possible with the smaller . varying z2 has little effect because appears linearly in eqn (5) and t(z) is roughly linear, so that αs will be adjusted during the regression by an amount roughly proportional to the product of the lapse rate dt/dz and the difference in z2, so as to match the observed bs as well as possible. the values for the critical direction φ′ are slightly different for kongsvegen and the two smaller glaciers austre brøggerbreen and midre lovénbreen. this might reflect local topographic effects as the accumulation area of the smaller glaciers is protected from southerly winds by surrounding mountains, whereas snowfall on the more f w f w t exposed kongsvegen is more susceptible to wind redistribution. on the other hand, the differences in critical direction φ′ are relatively small, so this may simply reflect random errors in the data. sensitivities of calculated bw and bs to hypothetical warming ∆t or increased precipitation ∆f are shown in table 4. sensitivities to ∆t are less than those found by dewoul & hock (2005), and sensitivities to ∆f are about the same. a possible explanation of the lower bs sensitivities compared with those of dewoul & hock (2005) is that the upper-air model has arbitrarily fixed dates, and might therefore miss some ablation occurring in may or september. reconstructed mass balance, 1948–2005 for each glacier, coefficients of eqns (4) and (5) obtained over the period of record (por) of observations were applied to upper-air data from prior to the por back to 1948. cumulative for brøggerbreen and lovénbreen is formed from for the years before the por, and from observed bn during the por. for kongsvegen, however, the model was used for 1948–1966, but for 1967–1987 was taken to be the average of the model estimate and that of the linear correlation with brøggerbreen. as was the case for all seven glaciers in southern norway, where the record from storbreen spanned the entire period of model results, the average of the model and the linear correlation with storbreen was a more accurate estimator than either the model alone or the correlation alone. for kongsvegen, the rms error for the model was 0.22, and for the correlation with brøggerbreen the rms error was 0.18. for the average of the model and the correlation it was 0.17. cumulative balance before 2005 (fig. 5) is defined by (7) here, bj is the value of in year j and b2005 is defined to be zero. bn* b b bn w s* * *= + bn* b bj j j = − +∑ 1 2004 * . bn* table 4 sensitivity (m water equivalent [m w.eq.]) to +1°c temperature change and to a 10% increase in precipitation flux f, from the upper-air model and from dewoul & hock (2005). glacier upper-air dewoul & hock dbw/dt dbs/dt dbn/df dbw/dt dbs/dt dbn/df austre brøggerbreen −0.06 −0.33 +0.06 −0.47 midre lovénbreen −0.06 −0.30 +0.07 −0.56 kongsvegen −0.06 −0.29 +0.07 −0.02 −0.41 +0.05 fig. 4 model (line) and observed seasonal mass balance components (�, winter balance [bw]; �, summer balance [bs]). (a) austre brøggerbreen, (b) midre lovénbreen, (c) kongsvegen. 1960 1980 2000 -1 0 +1 -1 0 +1 -1 0 +1 m a ss b a la n ce (m w .e q .) (a) (b) (c) l. a. rasmussen & j. kohler three svalbard glaciers reconstructed back to 1948 polar research 26 2007 168 – 174 © 2007 the authors 173 for the years when bn was measured, uncertainty is taken to be ∆obs = 0.3 m w.eq., and for years when it was not, (8) in which the rmsn values from lines 1, 2 and 5 of table 3 are used for ∆est. on the assumption that errors in the combined reconstructed–observed series are uncorrelated from year to year, the uncertainty in the cumulative value bj is (9) the cumulative curves in fig. 5 are shown with a ±1σ band. if there are systematic errors in the series, however, the true σj will be larger. between the periods 1948–1967 and 1968–2005, net balance bn became more negative, as shown by the change of mean slope of the cumulative curves in fig. 5. this was caused by bs becoming more negative, whilst bw was little changed. for austre brøggerbreen between these periods, the mean (eqn 5) increased from 1.19 to 1.64°c, but the mean (eqn 4) declined only from 2.41 to 2.36 m s−1. lefauconnier & hagen (1990) used multivariable linear regression to relate bn at brøggerbreen to the july– august temperature and the september temperature at longyearbyen over the period 1967–1988 with r 2 = 0.52. ∆ ∆ ∆= +obs est ,2 2 s j j j = ∑ ∆2 2004 . bn* t f w they obtained cumulative changes of −18 m over 1912– 1948 and −9 m over 1948–1967. the 1948–1967 cumulative change from the upper-air model (fig. 5) was −6 m. linear regression over the period of measurements of bn at the three glaciers had r = 0.96 between brøggerbreen and lovénbreen and 0.90 between brøggerbreen and kongsvegen (see also table 2). when these regression coefficients are applied to the −18 m cumulative change found by lefauconnier & hagen (1990), at brøggerbreen, the 1912–1948 changes are −15 m at lovénbreen and −2 m at kongsvegen. combined with the 1948–2005 changes (fig. 5), the 1912–2005 changes are −42 m at brøggerbreen, −33 m at lovénbreen and 0 m at kongsvegen. conclusions the upper-air model gives a good fit to the observed balances, is substantially better than another published model for bw at two glaciers, and is moderately worse for bs. its sensitivity of bs to warming is less than that calculated by the other model, and its sensitivity of bn to increased precipitation is about the same. the upper-air model has the advantage of using a database maintained as an integral part of an ongoing major scientific enterprise as its input. calculations can therefore easily be extended as future mass balance measurements become available. moreover, the model can also be used to estimate mass balance for years in which it is not measured. it could also be easily applied to mass balance records for other glaciers in svalbard. using upper-air data only at 0 coordinated universal time (utc) would probably give results that would be nearly as good as those obtained here by using upper-air values four times a day. acknowledgements this work was funded from the us national science foundation grant opp-0240861. discussion with h. conway improved our interpretation of results. we are grateful for comments by mark dyurgerov and an anonymous reviewer, which enabled us to clarify several points, leading to a much improved paper. references andreassen l.m., elvehøy h., kjøllmoen b., engeset r. & haakensen n. 2005. glacier mass balance and length variations in norway. annals of glaciology 42, 317–325. bevington p.r. 1969. data reduction and error analysis for the physical sciences. new york: mcgraw hill. braithwaite r.j. & zhang y. 1999. relationships between interannual variability of glacier mass balance and climate. journal of glaciology 45, 456–462. fig. 5. reconstructed mass balance (m water equivalent [m w.eq.]) prior to 2005, which is adopted as the datum according to eqn 7. the error band is shown as ±1σ (eqn 9). the short vertical line indicates the start of observations. (a) austre brøggerbreen, (b) midre lovénbreen and (c) kongsvegen. 1950 1960 1970 1980 1990 2000 2010 0 (a) +20 +10 0 (b)+20 +10 0 (c) -10 +10 c u m u la tiv e m a ss b a la n ce (m w .e q .) 174 polar research 26 2007 168 – 174 © 2007 the authors three svalbard glaciers reconstructed back to 1948 l. a. rasmussen & j. kohler dewoul m. & hock r. 2005: static mass balance sensitivity of arctic glaciers and ice caps using a degree-day approach. annals of glaciology 42, 217–224. dyurgerov m.b. & meier m.f. 1999. analysis of winter and summer glacier mass balance. geografiska annaler 81a, 541– 554. forland e.j. & hanssen-bauer i. 2000. increased precipitation in the norwegian arctic: true or false? climate change 46, 485–509. forland e.j. & hanssen-bauer i. 2003. past and future climate variations in the norwegian arctic: overview and novel analyses. polar research 22, 113–124. hagen j.o., kohler j., melvold k. & winther j.-g. 2003. glaciers in svalbard: mass balance, runoff and freshwater flux. polar research 22, 145–159. hagen j.o. & leistøl o. 1990. long-term glacier mass-balance investigations in svalbard, 1950–88. annals of glaciology 14, 102–106. hayes p.s., rasmussen l.a. & conway h. 2002. estimating precipitation in the central cascades of washington. journal of hydrometeorology 3, 335–346. kalnay e., kanamitsu m., kistler r., collins w., deaven d., gandin l., iredell m., saha s., white g., woollen j., zhu y., chelliah m., ebisuzaki w., higgins w., janowiak j., mo k.c., ropelewski c., wang j., leetma a., reynolds r., jenne r., joseph d. 1996. the ncep-ncar 40-year reanalysis project. bulletin of the american meteorological society 77, 437–471. kistler r., kalnay e., collins w., saha s., white g., woollen j., chelliah m., ebisuzaki w., kanamitsu m., kousky v., vanden dool h., jenne r., fiorino m. 2001. the ncepncar 50-year reanalysis: monthly means cd-rom and documentation. bulletin of the american meteorological society 82, 247–267. kohler j. & aanes r. 2004. effect of winter snow and groundicing on a svalbard reindeer population: results of a simple snowpack model. arctic, antarctic, and alpine research 30, 333–341. lefauconnier b. & hagen j.o. 1990. glaciers and climate in svalbard: statistical analysis and reconstruction of the brøggerbreen mass balance for the last 77 years. annals of glaciology 14, 148–152. lefauconnier b., hagen j.o., ørbaek j.b., melvold k. & isaksson e. 1999. glacier balance trends in the kongsfjorden area, western spitsbergen, svalbard, in relation to the climate. polar research 18, 307–313. nesje a., lie o. & dahl s.o. 2000. is the north atlantic oscillation reflected in scandinavian glacier mass balance records? journal of quaternary science 15, 587–601. oerlemans j. 1993. a model for the surface balance of ice masses: part 1. alpine glaciers. zeitschrift für gletscherkunde und glazialgeologie 27–28, 1991–1992, 63–83. oerlemans j. 2001. glaciers and climate change. exton, pa, usa: a.a. balkema. pohjola v.a. & rogers j.c. 1997. atmospheric circulation and variations in scandinavian mass balance. quaternary research 47, 29–36. rasmussen l.a. 2005. mass balance of vatnajökull outlet glaciers reconstructed back to 1958. jökull 55, 139–146. rasmussen l.a. in press. spatial extent of influence on glacier mass balance of north atlantic circulation indices. terra glacialis. rasmussen l.a. & conway h. 2001. estimating south cascade glacier (washington, u.s.a.) mass balance from a distant radiosonde and comparison with blue glacier. journal of glaciology 47, 579–588. rasmussen l.a. & conway h. 2003. using upper-air conditions to estimate south cascade glacier (washington, u.s.a.) summer balance. journal of glaciology 49, 454–462. rasmussen l.a. & conway h. 2004. climate and glacier variability in western north america. journal of climate 17, 1804–1815. rasmussen l.a. & conway h. 2005. influence of upper-air conditions on glaciers in scandinavia. annals of glaciology 42, 402–408. rasmussen l.a., conway h. & hayes p.s. 2000. the accumulation regime of blue glacier, u.s.a., 1914–96. journal of glaciology 46, 326–334. von storch h. 1999. on the use of “inflation” in statistical downscaling. journal of climate 12, 3505–3506. washington r., hodson a., isaksson e. & macdonald r. 2000. northern hemisphere teleconnection indices and the mass balance of svalbard glaciers. international journal of climatology 20, 473–487. doi:10.3402/polar.v34.21412 r e s e a r c h / r e v i e w a r t i c l e hermit crabs (pagurus spp.) at their northernmost range: distribution, abundance and shell use in the european arctic piotr balazy,1 piotr kuklinski,1,2 maria włodarska-kowalczuk,1 david barnes,3 monika kędra,1 joanna legeżyńska 1 & jan marcin węsławski 1 1 marine ecology department, institute of oceanology, polish academy of sciences, powstancow warszawy 55, pl-81-712 sopot, poland 2 department of life sciences, natural history museum, cromwell road, london sw7 5bd, uk 3 british antarctic survey, madingley road, high cross, cambridge cb3 oet, uk keywords hermit crabs; svalbard; arctic; fjords. correspondence piotr balazy, marine ecology department, institute of oceanology, polish academy of sciences, powstancow warszawy 55, pl-81712 sopot, poland. e-mail: balazy@iopan.pl abstract hermit crabs are important components of arctic benthic systems, yet baseline data on their densities and distribution patterns in this rapidly changing region are still scarce. here we compile results of numerous research expeditions to svalbard, the barents sea and northern norway that were carried out from 1979 to 2011 by the institute of oceanology, polish academy of sciences. the diversity of hermit crabs at the northern edge of their occurrence is very low; in svalbard waters only one species (pagurus pubescens) was detected. another species (p. bernhardus), found in northern mainland norway, north of the arctic circle, is likely to extend its distribution northward as the climate warms. where the two species co-occur, competition between them probably accounts for the smaller sizes and poorer quality shells used by p. pubescens. the composition of the mollusc shells inhabited by these crabs differs between northern norway and svalbard, reflecting local mollusc species pools. hermit crab densities were significantly higher than previously reported (max. mean 10 ind. m �2 ), suggesting their increasing level of dominance in benthic communities in the studied areas. the first to report the distribution of hermit crabs among habitats, this study showed that most individuals occurred at shallow depths (5�150 m), away from glacier termini and on hard bedrock rather than on soft substrata. hermit crabs (paguroidea, decapoda) are common and abundant in almost all types of benthic habitats worldwide (lancaster 1988). they are opportunistic feeders, scavengers or predators (hazlett 1981) and are consumed by demersal fish, seabirds, brachyuran crabs, octopus and starfish (lancaster 1988 and references therein). the wide distribution of hermit crabs is facilitated by their pelagic larvae: typically four free-swimming zoeal stages and one megalopal stage, which, after metamorphosis, turns into a young crab (lancaster 1988). due to a high fecundity *1200 eggs for a female pagurus bernhardus*hermit crab larvae can be numerous in plankton communities (jackson 1913; thorson 1946; bookhout 1964; weydmann et al. 2013). in favourable laboratory conditions (108c and salinity of 30�35), full development can be completed within 52�64 days (p. bernhardus, bookhout 1964), but lower temperature and salinity along with reduced food availability or shortage of suitable habitat and resources (empty gastropod shells) may significantly prolong, or prevent, larval development (bookhout 1964; roberts 1971; warner 1977; dawirs 1979, 1981; harms 1992; harvey 1996). through the use of gastropod shells pagurids provide transportation and secondary habitat for epibionts (williams & mcdermott 2004), typically harbouring higher numbers of associated species than other substrates, such as similar sized live gastropods or pebbles (balazy & kuklinski 2013). therefore, they are a good example of ecosystem engineers (stachowitsch 1977; mclean 1983; jones et al. 1994, 1997; reiss et al. 2003; bell 2005; balazy & kuklinski 2013) and interesting model organisms for testing hypotheses on resource use and biodiversity patterns (williams & mcdermott 2004). polar research 2015. # 2015 p. balazy et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 previous research on hermit crabs has been mostly carried out in tropical and temperate seas (abrams 1980; barnes 1997, 1999; barnes & de grave 2000; sandford 2003; fransozo et al. 2007; zuschin & pille 2007; ayresperes & mantelatto 2008; bach & hazlett 2009; tricarico et al. 2009). studies from higher latitudes are still scarce, partly because of logistic constraints (but see samuelsen 1970; squires et al. 1993; barnes et al. 2007; kuklinski et al. 2008; balazy & kuklinski 2013; peura et al. 2013). in norwegian waters, pagurid fauna is represented by several species, including anapagurus chiroacanthus, a. laevis, pagurus alatus, p. bernhardus, p. cuanensis, p. prideaux and p. pubescens (sandberg & mclaughlin 1998; brattegard & holthe 2001). the species richness of hermit crabs significantly declines northwards (abele 1974), and is limited to three taxa (p. pubescens, p. bernhardus and a. chiroacanthus) in northern norway (sandberg & mclaughlin 1998; barnes et al. 2007) and only two taxa in svalbard waters. pagurus pubescens, which has the most northward range among the north atlantic hermit crabs, commonly occurs around the svalbard archipelago (sandberg & mclaughlin 1998; selbie 1921). the second species reported from this area, but rarely found, is p. bernhardus (sandberg & mclaughlin 1998; gulliksen et al. 1999; gulliksen & svensen 2004). this poleward impoverishment of hermit crab species is most likely the result of lowered temperatures (lindley 1998) and is matched by an even more severe poleward decline in the southern hemisphere. the ongoing environmental change (temperature increase, ice loss, acidification) and increase of anthropogenic pressure (oil drilling and fisheries) may lead to substantial ecological changes within arctic benthic communities (core writing team et al. 2007; dawson et al. 2011; wassmann et al. 2011; węsławski et al. 2011; duarte et al. 2012; wang & overland 2012). climateforced northward expansions have been observed for boreal species (berge et al. 2005) and predicted for coldwater arctic species (węsławski et al. 2010; węsławski et al. 2011). in svalbard, hermit crabs of the genus pagurus occur at their northernmost limit (birula 1907; heegaard 1941) and may therefore act as good indicators of physical changes. increased levels of oceanographic variability (walczowski & piechura 2006; walczowski et al. 2012) and fishery-related disturbance (berge et al. 2009) will likely have a positive effect on their distribution range, species richness and abundance. berge et al. (2009) have recently proved that the composition of decapod fauna in spitsbergen waters has not changed during the last 50 years. on the other hand, they have found evidence for changes in the decapod community structure, with opportunistic scavenging crabs becoming increasingly dominant and specialized predatory shrimps correspondingly decreasing. knowledge of pagurid distribution, density and gastropod shell use remains scattered and incomplete in the arctic. to the best of our knowledge the only study available from svalbard waters is by barnes et al. (2007); however, the scale of this was limited and it did not cover substratum choice. here we compile data gathered during numerous research expeditions carried out by the institute of oceanology of the polish academy of sciences (io pan) during the last four decades to svalbard, the barents sea and northern norway. samples were taken across a range of depths (3�3000 m) and habitats in an attempt to establish robust baseline information as a reference or starting point for further ecological assessments. material and methods study area this study was carried out in northern norway (698n) and two high-arctic areas: the barents sea’s shallow bank (svalbard bank) and the western coast of spitsbergen, the biggest island of the svalbard archipelago (fig. 1). the hydrology of these areas is shaped by the interplay of the two large water masses of atlantic and arctic ocean origin. three sites selected around tromsø in northern norway (kvalsund, mjøsund, grøtfjord) as well as the western side of spitsbergen are influenced by the relatively warm and saline (t�38c, s �35; loeng 1991) waters of the north atlantic and the west spitsbergen current. despite their high latitude (76�808n) the west spitsbergen fjords have a mild, rather than arctic character (hop et al. 2002; svendsen et al. 2002). they remain ice-free most of the year; during winter the surface water freezes for a few months (węsławski et al. 1988). the southernmost fjord of the island, hornsund, is strongly affected by slightly less saline and colder (tb08c, s 34.3�34.8; loeng 1991) waters originating in the arctic ocean and transported by the east spitsbergen current (swerpel 1985). a front between north atlantic and arctic water masses passes both sides of the svalbard bank, an elongated shallow bank that rises from the bottom of the barents sea up to 30 m under the surface. this largest open-shelf cold-water carbonate platform in the arctic, built from shell fragments mixed with very coarse sand and gravel (elverhøi & solheim 1983; henrich et al. 1997) is one of the most productive areas in the barents sea (sakshaug et al. 2009). in its central part, arctic water mixes with the meltwater which has been hermit crabs at their northernmost range p. balazy et al. 2 (page number not for citation purpose) citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 fig. 1 distribution and abundance of hermit crabs pagurus spp. in the studied areas. data on pelagic zoea larvae are from węsławski et al. (1991), węsławski, koszteyn et al. (1999), węsławski, stempniewicz et al. (1999), kwasniewski et al. (2010), jakubas et al. (2011), kwasniewski et al. (2012), weydman et al. (2013) and gluchowska et al. (unpubl. ms.). p. balazy et al. hermit crabs at their northernmost range citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 heated by the atmosphere during the summer (t 1�38c, sb34.4; loeng 1991). freshwater runoff from melting glaciers or glacier-fed rivers has a significant impact on the hydrological conditions prevailing inside the fjords. apart from decreased salinity and iceberg scouring, large amounts of sedimenting mineral particles can result in declines in benthic species richness, diversity and abundance, especially in the innermost parts of the fjords, close to tidal glaciers (włodarska-kowalczuk et al. 2005). the sediment accumulation rates in kongsfjorden, the fjord with the most active glacier in the svalbard archipelago* kongsbreen (lefauconnier et al. 1994), range from 20 000 g m �2 year �1 near the glacier front to 200 g m �2 year �1 at the fjord mouth (svendsen et al. 2002). as a result, the fjords seafloor is mainly covered by soft homogeneous mud with ice-rafted clasts (elverhøi et al. 1983). hard substrata habitats*rocky shelves and mixed boulder fields with coarser fractions such as pebbles, cobbles and boulders*mostly occur at the outer parts of the fjords, where stronger bottom currents occur (kaczmarek et al. 2005). soft bottom macrobenthic assemblages are dominated mostly by infaunal, deposit feeding or carnivorous bivalve and polychaete species (włodarska-kowalczuk et al. 1998; włodarska-kowalczuk et al. 2007). in the shallow subtidal zone of outer fjord basins, dense algae (laminaria spp.) and associated diverse epibenthic assemblages of ascidians, barnacles, bryozoans, cnidarians, sedentary polychaetes and sponges occur on hard bedrock shelves (barnes & kuklinski 2005; barnes et al. 2007). hermit crabs (pagurus spp.), other decapods, such as the spider crab hyas araneus or shrimps (lebbeus polaris, eualus gaimardii, sclerocrangon boreas) are common benthic predatory and scavenging fauna in these habitats (kaczmarek et al. 2005; berge et al. 2009). sampling material was collected during cruises of the rv oceania and land-based expeditions to the svalbard archipelago organized by io pan in the summer seasons between 1979 and 2011. material was collected at the svalbard bank by the rv oceania in 2009. samples in northern norway, were collected during land-based expeditions in 2009 and 2010. in total, 240 stations were sampled from the major fjords of west spitsbergen, at svalbard bank and at three sites in northern norway, across a depth range of 2�2977 m. most of the sampling sites were localized in two west spitsbergen fjords*hornsund and kongsfjorden (fig. 1)*both european marine biodiversity research sites (warwick et al. 2003). samples were collected using different sampling methods that were considered most appropriate across depth zones and habitats (table 1). quantitative samples from table 1 details of sampling campaigns. abundance values are mean (9standard error) and, in italics, maximum abundance. year site depths (m) sampling technique number of stations number of samples abundance (ind. m�2) reference 2009 smeerenburgfjorden 7�177 scuba diving dredge 4 4 only qualitative this paper 2007 2009 magdalenefjorden 12�103 scuba diving dredge van veen grab 7 17 10 (90.00) 10 this paper 1996�2001 2006 2009 kongsfjorden 4�2977 scuba diving dredge van veen grab 102 239 6 (90.45) 20 włodarska-kowalczuk et al. 2004 kaczmarek et al. 2005 kędra et al. 2010 2009�2011 isfjorden 3�289 scuba diving dredge van veen grab 35 119 7 (90.11) 44 balazy & kuklinski 2013 this paper 2000�2001 van mijenfjorden 4�104 van veen grab petit ponar grab 8 24 absent this paper 1979�1982 2002�2003 2005 2007 2009 hornsund 11�237 scuba diving dredge van veen grab benthic lander 84 138 5 (90.31) 10 this paper 2009 svalbard bank 39�150 dredge van veen grab benthic lander 17 70 4 (90.24) 30 kędra et al. 2013 2009�2011 northern norway 3�20 scuba diving 3 15 7 (90.30) 28 this paper hermit crabs at their northernmost range p. balazy et al. 4 (page number not for citation purpose) citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 the deeper subtidal (�30 m) were collected using a 0.1 m 2 van veen grab or 0.045 m 2 petit ponar grab. presence/ absence data were scored from dredge sampling as well as videos recorded by a benthic lander and an underwater ‘‘bottom-looking’’ drop camera. in shallow (b20 m) areas unsuitable for sampling directly from research vessels, and on bottom types where conventional surface-operated sampling gear has a limited efficiency (e.g., hard bedrock), samples were collected by scuba divers. in this case, hermit crab density estimates were obtained with the use of a (0.5 �0.5 m) 0.25 m2 quadrat. we counted all individuals within each of three quadrats placed haphazardly on the sea bottom at 3, 5, 10, 15 and 20 m depths. at each site, the bottom type was classified by visual inspection by divers as hard bedrock (sites s1, s2, s5), mixed substrata (sand and gravel; sites s6, t1, t3) or soft bottom (sand and mud; sites s3, s4). the samples were fixed in 4% buffered formaldehyde and transported to the laboratory. hermit crab species, gender, shield length, wet mass, presence of parasites and overgrowing epibionts (larger �1 mm) were noted. crabs were classified into five size classes on the basis of shield length (class 1: 0�3.5 mm; class 2: 3.5�5.0; class 3: 5.0�6.5; class 4: 6.5�8.0; class 5: above 8.0). gastropod shells were identified to species or, when damaged, to the lowest possible taxonomic level. statistical analysis due to significant heterogeneity of variances, a nonparametric kruskal�wallis test was used to test for differences in hermit crab abundance with depth and size. post-hoc pair-wise testing was performed with the use of mann-whitney’s u-test. the hurlbert rarefaction diversity index (es[n]) (hurlbert 1971) was used in order to compare diversity of gastropod shells used by hermit crabs between the sites with different numbers of individuals collected. accumulation curves of the different gastropod shell types used were plotted for samples collected at each site. species accumulation curves, es[n] were computed and plotted with the primer version 6 software package (clarke & gorley 2001). the statistical analyses were performed in statistica version 10 (statsoft inc.). results distribution and abundance hermit crabs were present in all study areas except for van mijenfjorden, a relatively poorly sampled fjord in spitsbergen (fig. 1). the most northerly site with hermit crabs present was smeerenburgfjorden (79.88n). hermit crabs were most abundant in isfjorden, where abundance reached 44 ind. m �2 in a single sample (table 1, fig. 1). up to 30 ind. m �2 were found at svalbard bank, while in northern norway maximum abundance was 28 ind. m �2 . mean abundances calculated from all samples collected at a given site never exceeded 10 ind. m �2 (table 1). very few crabs were found in the innermost part of the study fjords and none close to glaciers. hermit crabs in spitsbergen fjords were found only between 5 m and 150 m depth despite samples being collected at greater depths (fig. 2). at svalbard bank, they similarly occurred down to 140 m. in the shallow sublittoral (3�20 m), diver-held quadrats revealed significant differences in abundance of hermit crabs among different depth zones (kruskal-wallis, h(4, 114) �20.78, pb0.001; fig. 3): shallow (3 and 5 m) versus deeper (10, 15 and 20 m) (mann-whitney u, pb0.05). the mean abundance was significantly higher at 9�10.7 ind.m�2 at 10�20 m compared to 1.7�2.7 ind.m�2 at 3�5 m. this ‘‘overall’’ abundance�depth pattern was driven by significant depth differences at bedrock sites (kruskal�wallis, h(4, 45) �28.03, pb0.001; mann-whitney u, pb0.01; fig. 3). however, on mixed and soft bottom sites we found no differences with depth (kruskal� wallis, p�0.05). the differences between the three bottom types were found at each study depth (kruskal� wallis,pb0.05; fig. 3)except10m(kruskal�wallis, h(2, 24)� 5.83 p �0.05). at 15 and 20 m, hermit crabs were more abundant at sites with hard (mean 16.4 and 16.7 ind. m �2 , respectively) than soft substrata (mean 2.0 and 1.3 ind. m �2 ; mann-whitney u, pb0.05). samples from mixed substrata in this depth range did not differ significantly from the other two bottom types (mean 10.0 and 9.3 ind. m �2 ; mann-whitney u, p�0.05). no hermit crabs were found at the shallowest depths at sites with soft (3 m) and hard bedrock (3 and 5 m). mean hermit crab abundance (7.1 at 3 m and 0.7 ind. m �2 at 5 m) on mixed substrata differed significantly from those at 3 and 5 m on 0 50 100 150 200 250 300 350 400 1050 15 20 25 30 35 40 45 50 d e p th (m ) distance from the glacier (km) = < 10 m–2 = < 20 m–2 = > 20m–2 present absent fig. 2 hermit crab occurrence and abundance in relation to depth and distance to glaciers. p. balazy et al. hermit crabs at their northernmost range citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 bedrock (mann-whitney u, pb0.05) and 3 m on soft substrata (mann-whitney u, pb0.05). species, size, gender and parasitism pagurus pubescens was the only species found at svalbard bank and in spitsbergen fjords, whilst in northern norway p. bernhardus was also noted and comprised 34% of all individuals collected. each species in northern norway had different size ranges, as measured in shield lengths: p. pubescens 2.08�7.80 mm; p. bernhardus 1.40�10.46 mm. specimens of p. bernhardus (mean 6.7 mm) were significantly larger than p. pubescens (mean 4.7, mann-whitney u, pb0.001). males of both hermit crab species were significantly larger in shield length than females (mannwhitney u, pb0.05). gender ratios were close to equal. across the study areas 17% of p. pubescens were parasitized by peltogaster paguri but just 6% of both species were overgrown by epibionts (juvenile serpulids, spirorbid circeis armoricana, cirriped semibalanus balanoides, bryozoan patinella sp. and hydroids). significant differences in the size of hermit crabs were found between sites (shield length: kruskal-wallis, h(9, 391) �65.79, pb0.001; wet mass: kruskal�wallis, h(9, 391) �78.23, pb0.001; fig. 4). in terms of shield length and wet mass, the largest specimens were p. bernhardus collected at site t3 in northern norway (mean shield length 8.2 mm and wet mass of 4.0 g). specimens collected at this site were nearly two times longer and over four times heavier than those from (nearby) site t2, northern norway. the largest p. pubescens were found at the s2 site in isfjorden (mean shield length 6.9 mm and wet mass of 2.6 g). kw-h(4, 45) = 28.03 p<0.001 hard bottom 0 2 4 6 8 10 12 14 16 18 20 22 24 all bottom types kw-h(4, 114)= 20.78, p<0 .001 0 2 4 6 8 10 12 14 16 18 20 22 24 n ( in d .m – 2 ) n ( in d .m – 2 ) kw-h(4, 39)= 2.65, p>0.05 mixed bottom 3 5 10 15 20 depth (m) kw-h(4, 30) = 2.99, p > 0.05 soft bottom 3 5 10 15 20 depth (m) fig. 3 mean values with standard errors of hermit crab (pagurus spp.) abundance at different depths and bottom types. only samples collected in shallow subtidal (depths down to the 20 m) are presented. hermit crabs at their northernmost range p. balazy et al. 6 (page number not for citation purpose) citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 shell use hermit crabs inhabited shells belonging to 23 taxa (table 2). species accumulation curves showed that the highest richness of gastropod shells (11 taxa) were used by p. pubescens at svalbard bank site b2 and smeerenburgfjorden, spitsbergen (fig. 5). pagurus bernhardus was found in the fewest types of shells (in northern norway, three at t1 and t2; four at t3). however, this species was also less numerous in samples taken (table 2, fig. 5). interpolation of gastropod richness to the same level of 15 samples among all sites (as only 15 individuals of p. bernhardus were collected at t1) suggested that p. bernhardus inhabited fewer gastropod shell types than p. pubescens. (in northern norway, at site t1 there were three types for p. bernhardus and five for p. pubescens; at site t2, three for p. bernhardus and seven for p. pubescens. at site t3, both p. bernhardus and p. pubescens had four.) however, an es[15] analysis and species accumulation plot did not reveal any clear differences in the use of gastropod shells by p. pubescens with latitude. (in northern norway, at site t1 there were five, at t2 seven and at t3 four; at the svalbard bank, at site b1 there were four and at b2 seven; in spitsbergen, at site s1 there were seven, at s2 four, at s3 six, at kongsfjorden five and at smeerenburgfjorden six.) shells of buccinum undatum were used at all study sites and by both hermit crab species. shells belonging to other members of the buccinidae family (b. glaciale, b. scalariforme and colus kroeyeri) were also common in collected material (table 2). in northern norway, 42% of all shells used by p. bernhardus belonged to the common periwinkle littorina littorea and 38% came from the large whelk b. undatum. the other hermit crab species, p. pubescens, used mostly nucella lapillus (34%), littorina littorea (17%) and l. obtusata (13%) in northern norway. in contrast, at svalbard bank and spitsbergen, the most inhabited shells were b. undatum (26%), b. glaciale (23%) and margarites groenlandicus (14%). in general, the majority of small p. bernhardus used gibbula cineraria shells. medium-sized individuals inhabited mainly l. littorea shells, whilst the largest were found primarily in shells of buccinum spp. (b. undatum, b. scalariforme and b. polare; fig. 6). the species composition of shells used by p. pubescens found in northern norway was similar, (except one additional gastropod species: nucella lapillus), but the proportion in which they were used differed across size classes. the smallest p. pubescens individuals occupied g. cineraria, l. obtusata and l. littorea shells. in medium size classes, n. lapillus constituted a significant part, while the largest grouping (class 4) was dominated by littorina spp. at svalbard bank and spitsbergen, buccinum spp. predominated in almost all size classes. the smallest p. pubescens in those two areas inhabited mainly shells of m. groenlandicus and cryptonatica affinis, which was more plentiful at svalbard bank (fig. 6). in northern norway, 31% of shells used by p. bernhardus and 34% of shells used by p. pubescens were defective shells with cracks and holes. damaged shell use was higher in spitsbergen (41%) than at svalbard bank, where damaged shells accounted for only 12%. no universal trend in the use of broken shells was observed in the five hermit crab size classes among the study areas (fig. 7). in p. bernhardus, the highest proportion of damaged shells were used by small individuals, however, these data should be treated with caution as the sample size was small. the largest size classes of p. pubescens in northern norway and svalbard bank used unbroken shells, but again, the 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0 4.4 4.8 kw-h(9, 391) = 78.23, p < 0.001 t1 t2 t3 b1 b2 s1 s2 s3 k smr northern norway svalbard bank spitsbergen 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 kw-h(9, 391) = 65.79, p < 0.001 w e t m a ss ( g ) s h ie ld ( m m ) fig. 4 shield length and wet mass of hermit crabs (open squares, pagurus bernhardus; filled squares, p. pubescens) collected at sites in northern norway (t1, t2, t3), the svalbard bank (b1, b2) and spitsbergen (s1, s2, s3, s4, k, smr). mean values with standard errors and results of a kruskal-wallis test for difference among sites are presented. p. balazy et al. hermit crabs at their northernmost range citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 northern norway data set had few samples. at spitsbergen, the largest proportion of broken shells was recorded in the medium (3) and large size classes (4, 5). unsurprisingly, there was a strong positive correlation between hermit crab wet mass and mass of its shell (r 2 �0.787, t �26.09, pb0.001). discussion hermit crab diversity, distribution and abundance despite the fact that the current study attempted to cover large geographic areas we found only two species (p. bernhardus and p. pubescens) from just one genus in table 2 shell use by pagurus pubescens (pp), p. bernhardus (pb) at sites in northern norway, at the svalbard bank and on spitsbergen. pp and pb in boldface denotes more than five individuals; normal type represents five or fewer individuals. northern norway a svalbard bank b spitsbergen c shell species t1 t2 t3 b1 b2 s1 s2 s3 k smr amauropsis islandica pp boreotrophon truncatus pp pp pp pp buccinum glaciale pp pp pp pp pp pp pp buccinum polare pb pp pp pp buccinum scalariforme pp pb pp pp pp pp buccinum undatum pp pb pp pb pp pb pp pp pp pp pp pp pp buccinum sp. pp pp pp pp pp colus kroeyeri pp pp pp pp colus latericeus pp buccinidae pp pp pp pp cryptonatica affinis pb pp pp pp pp pp lunatia montagui pp lunatia pallida pp pp pp pp pp naticidae pp pp gibbula cineraria pp pp pb pp littorina littorea pp pb pp pb pp pb littorina obtusata pp pp margarites groenlandicus pp pp pp pp pp pp nucella lapillus pp pp pp oenopota pyramidalis pp pp muricidae pp neogastropoda pp undetermined pp pp pp pp a at site t1, there were 15 p. bernhardus individuals and 19 p. pubescens; at t2, there were 19 p. bernhardus and 25 p. pubescens; at t3, there were 18 p. bernhardus and 32 p. pubescens. b at the svalbard bank there were 50 individuals at each site. c at each site in spitsbergen (isfjorden: s1, s2, s3; kongsfjorden: k; smeerenburgfjorden: smr), there were 50 individuals. fig. 5 species accumulation curves of gastropod shells types used by hermit crabs. hermit crabs at their northernmost range p. balazy et al. 8 (page number not for citation purpose) citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 fig. 7 percentage of broken shell used by five hermit crab size classes in different areas. above each column number of collected individuals is presented. fig. 6 percentage of shell used by five hermit crab size classes in different areas. above each column number of collected individuals is presented. p. balazy et al. hermit crabs at their northernmost range citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 northern norway and only the latter species at svalbard bank and in spitsbergen. the svalbard archipelago is known as the northernmost (and lower temperature) limit of hermit crab occurrence (birula 1907; heegaard 1941) so a paucity of species is unsurprising. a previous study by barnes et al. (2007), performed across similar sites, reported a single specimen of another hermit crab species, anapagurus chiroacanthus, in northern norway (at t2, fig. 1). for svalbard waters, the regional species checklists also report the presence of p. bernhardus (sandberg & mclaughlin 1998; gulliksen et al. 1999; gulliksen & svensen 2004; palerud et al. 2004). however, it appears to be very rare here as among 630 specimens collected during a five-year study in isfjorden, spitsbergen (pb & pk, unpubl. data), and among 347 hermit crab specimens gathered in other fjords of spitsbergen (barnes et al. 2007), no representative of p. bernhardus was found. furthermore, it was not found in other studies that focused on the decapod fauna in svalbard waters (christiansen & christiansen 1962; węsławski 1987; duris 1995; berge et al. 2009). therefore, we assume that the established range of this species’ geographical range does not extend this far north. sokolov (2006) classifies p. bernhardus as a warm atlantic or atlantic�mediterranean species with a range that follows the branches of the norwegian current along the western coasts of norway. pagurus pubescens is defined as a eurythermic and euryhaline decapod that is widely distributed in eastern arctic seas. if the trend of significant regional warming continues in the arctic the range of p. bernhardus would seem likely to extend northwards and be reported more commonly in the svalbard archipelago. such climate-forced range expansions are arguably already being observed, e.g., the recent reappearance of the mussel mytlius edulis in west spitsbergen fjords (berge et al. 2005). the only fjord surveyed in this study where no hermit crabs were found was van mijenfjorden. this is a semiclosed fjord system with some anthropogenic impact as there is an active coal mine located nearby. however, significantly measurable effects of mining activities on marine fauna have been described as restricted to places where the ships are loaded (renaud et al. 2007). it is therefore most likely that the absence of hermit crabs in our van mijenfjorden material results from low sampling effort, as only eight stations were investigated. no clear, large-scale trend in hermit crab abundance was apparent along the geographical gradient we studied (from northern norway to svalbard). instead, abundance turned out to be highly variable between sites, suggesting that local factors are decisive. interestingly, the abundance figures in the current study found abundance were higher than those reported by barnes et al. (2007) at the same sites in 2005 (7 versus 2 ind. m �2 in northern norway, 7 versus 2 ind. m �2 in isfjord and 6 versus 0.8 in kongsfjorden, this study). berge et al. (2009) speculated that a shift from specialist predators towards opportunistic, scavenging species, like hermit crabs, might have occurred over the last 100 years in isfjorden. our results support this hypothesis; however, due to paucity of the time series, annual fluctuations driven by natural factors such as variability in hydrological regimes and seawater temperature cannot be ruled out (renaud et al. 2008; berge et al. 2009). just after barnes et al. (2007) undertook their sampling, in 2005, a huge northward advance of atlantic waters and the highest recorded temperatures of the spitsbergen current were noted (walczowski et al. 2012). such a hydrologic event could increase the influx of larvae from lower latitudes and accelerate their development and enhance their survival rate (bookhout 1964; dawirs 1979; lindley 1998). as hermit crabs are mobile and capable of rapid dispersal (by larvae), their absence in fjord head regions suggests that they prefer conditions and/or habitats located in central and outer basins, away from sources of glacial or glaciofluvial outflows (usually in inner fjords). glaciers and glacier-fed rivers transport large amounts of freshwater and mineral material into the sea and strongly impact neighbouring benthic systems. sediments there are frequently resuspended and redeposited by gravity flows (zajączkowski & włodarska-kowalczuk 2007), subjecting benthic communities to physical disturbance by heavy sedimentation of mineral particles. these communities have impoverished standing stocks and diversity compared to outer fjord regions (włodarska-kowalczuk et al. 2007). larger, slow-moving organisms, such as hermit crabs, can be locally eliminated by unstable substrates that are often covered with a ‘‘fluffy layer’’ of unconsolidated sediment (włodarska-kowalczuk et al. 2005). high turbidity in surface waters together with strong mineral particles deposition result in low organic carbon concentrations in sediments of inner basins (e.g., winkelmann & knies 2005). this can have an additional negative effect on hermit crab populations as organic matter may constitute a supplementary source of food for depositfeeding hermit crabs (greenwood 1972; gerlach et al. 1976; fransozo et al. 1998). a wide depth range has been reported for p. pubescens (5�1079 m; ingle 1993) and p. bernhardus (intertidal: 1800 m; sandberg & mclaughlin 1998). however, our data suggest that in the arctic and sub-arctic fjords and coastal waters they occur mostly at depths shallower than 150 m (fig. 2). similarly, around the british isles, p. pubescens and p. bernhardus normally occur from 100 to 140 m, and are only occasionally found as deep as 500 m hermit crabs at their northernmost range p. balazy et al. 10 (page number not for citation purpose) citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 (hayward & ryland 1999). in isfjorden, p. pubescens has its maximum abundance above 50 m (christiansen & christiansen 1962). in hornsund and adjacent waters of southern spitsbergen, the highest concentrations of p. pubescens were noted between 20 and 30 m (magdziarz 1984) and between 21 and 50 m (węsławski 1987), which is consistent with our results (see fig. 2). a scarcity of pagurus spp. in the shallow waters (3�5 m) is most probably the result of high physical disturbance (wave and ice action) in the arctic. we did not observe any hermit crab ashore at low tide, whereas in lower latitudes (e.g., in the british isles) they are widely recorded in rocky tide pools and the intertidal zone (hayward & ryland 1999). substrate type is typically an important factor that determines the distribution of many benthic species, and this includes hermit crabs (samuelsen 1970; lancaster 1988 and references therein). as reported here, magdziarz (1984) found that p. pubescens at hornsund occurred mostly on hard (55%) or mixed bottom (rocks and mud, 37%), and only 8% on soft substrata. węsławski (1987) also noted that, except for mud and the phytal zone, hermit crabs were mostly found associated with stones and coralline red algae. likewise eriksson et al. (1975) showed that p. bernhardus, prefers hard substratum to sand. preference for hard substrata may actually be more prevalent than data suggest, given that the crevices that often characterize hard substrata make counts likely to be under-representations whilst on soft substrata the crabs are particularly conspicuous and difficult to overlook. more complex habitats support higher megafaunal densities (robinson & tully 2000) as they are usually more heterogeneous in structure and offer more food supplies and/or better shelter from predators (wahle & steneck 1991; stelle 1999; linnane et al. 2002; moksens 2002; pallas et al. 2006). even with the protection of gastropod shells, hermit crabs can be easily detected on monotonous mud or sand surfaces and predated by demersal fish (e.g., wolfish [anarhichas lupus] or ballan wrasse [labrus bergylta]; samuelsen 1970; falk-petersen et al. 2010), mammals (bearded seal [erignathus barbatus], grey seal [halichoerus grypus], walrus [odobenus rosmarus]; fay & burns 1988; lydersen et al. 1989; nammco 1997), larger hermit crabs (pb, pers. obs.) or other bottom-dwelling predators (lancaster 1988 and references therein). hermit crab size the maximum size of hermit crabs is speciesand genusspecific. pagurus bernhardus is generally larger than p. pubescens (sandberg & mclaughlin 1998; hayward & ryland 1999). previous findings from other regions suggest that in areas of sympatry with an aggressively dominant species, smaller hermit crab species may be forced to inhabit smaller shells (than normal) and therefore reach typically smaller sizes than in nearby, monospecific areas (bach et al. 1976; hazlett 1981 and references therein). the less competitive individuals forced to occupy lower quality shells have also been shown to have a worse reproductive success (e.g., elwood et al. 1995). it is unknown whether this is the case in northern norway, where the two species of hermit crabs co-occur. we found that p. pubescens from spitsbergen was, in general, larger in size than p. pubescens from northern norway. it has been suggested that some arthropods in cold waters can grow to larger sizes as a result of higher oxygen availability and have increased life spans at lower temperatures (chapelle & peck 1999, 2004). this factor might be also responsible for differences in sizes observed between warmer northern norway and colder, higher latitude sites. at a local scale, many other factors, like variable food supplies, shell resources, salinity or predation, can influence hermit crab sizes (kellogg 1976; bertness 1981a; yoshino et al. 2002; davenport 1972). in this study, sites varied considerably in terms of environmental conditions, making it hard to pinpoint factor(s) with the highest impact on hermit crab size. the smallest individuals were mainly found closer to river mouths (e.g., s1), highly influenced by freshwater runoff. many of the largest individuals occurred offshore (svalbard bank), close to the frontal zone of very productive and nutrient-rich water masses. shell use results from the present study indicate that, except for one site (t3), p. bernhardus used fewer shell types than p. pubescens. both species have been reported earlier to utilize shells of a similar number of gastropod species in southern (samuelsen 1970) and northern norway (barnes et al. 2007). our result is probably site-specific and was determined by the availability of suitable shells in the area or competition between sympatric hermit crab populations (vance 1972; bach et al. 1976; abrams 1980). if p. bernhardus is indeed a better competitor for shells, it can rely mostly on the available shells of one, most preferred type, while the other crab species is forced to search across the remaining pool of shells of less favourable characteristics, so its shell selections are less focused. indeed, the majority of individuals of p. bernhardus occupied the shells of littorina spp. and both the experimental studies and in situ observations of p. bernhardus showed that littorina spp. shells are strongly preferred over other types, such as gibbula spp. shells (elwood et al. 1979; jackson & elwood 1990). p. balazy et al. hermit crabs at their northernmost range citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 the greatest diversity of shells (11 taxa) was used at the site located the furthest north (smeerenburgfjorden). the greater richness in shells collected at spitsbergen in the present study seems to be at odds with much more diverse gastropod species pools in northern norway (133 species) compared to spitsberen (93 species; thorson 1944). yet barnes et al. (2007) demonstrated a lack of correlation between the latitude and number of shell types used despite the northward impoverishment of gastropods (roy et al. 1996; roy et al. 1998). evidently, the richness of gastropod shells utilized by hermit crabs cannot be used as a surrogate for regional benthic diversity as was proposed, e.g., for the dead mollusc assemblages accumulated on sandy shores (warwick & light 2002). most of the gastropod species that were represented among the shells collected in this study occur in both svalbard and continental norwegian waters. all the species are included in a checklist of marine molluscs of the continental norwegian waters (høsæter 1986), except for colus kroeyeri, buccinum glaciale and b. polare, which are considered arctic, circumpolar species that do not occur in norway (thorson 1944; macpherson 1971; bouchet & waren 1985). a notable difference in the composition of the shells collected in the two regions was the absence of littorina spp. shells at the sites in svalbard. litorina littorea, l. obtusata, gibbula cineraria and nucella lapillus are unlikely to occur in svalbard waters though they are included in the list of marine invertebrate species recorded around spitsbergen compiled by palerud et al. (2004); their presence in spitsbergen is not confirmed by other, more mollusc-oriented publications (thorson 1944; włodarska-kowalczuk 2007) or by the io pan data archives based on 20 years investigating svalbard benthic fauna (włodarska-kowalczuk et al., unpubl. data). in general, littorinids in the arctic are markedly impoverished as compared to northern norway. studies of the svalbard intertidal zone found only one periwinkle species: littorina saxatilis (węsławski et al. 1993; węsławski et al. 1997). these studies also found that total faunal densities and biomass were much lower than in similar habitats (rocky shores) of northern scandinavia. gastropod species richness at higher latitudes is much lower than in tropical or temperate regions, although 160 gastropod species occur in the svalbard archipelago (palerud et al. 2004), and up to 38 species have been be found in kongsfjorden, a single fjord in spitsbergen (włodarska-kowalczuk 2007). despite the variety of shells potentially available, most hermit crabs collected used only a few shell types. typically large specimens of p. bernhardus inhabited shells of a large whelk b. undatum and the periwinkle l. littorea, while the smallest were found mostly in shells of g. cineraria. although we did not perform any shell choice experiments, the fact that apart from the set of shells used by p. bernhardus, p. pubescens commonly inhabited nucella lapillus might indicate that there is some interspecific competition in these hermit crabs and that by using an additional shell type some resource use overlap is minimized (hazlett 1981). the lack of the largest specimens of p. pubescens in the collected samples further supports this (see discussion on crab size). pagurus pubescens from the svalbard bank and spitsbergen used mainly large buccinidae shells and small shells of cryptonatica affinis and margarites groenlandicus. two of these gastropod taxa (buccinidae and m. groenlandicus) have been previously noted as the most frequently exploited by hermit crabs and highly abundant in the environment (jensen & bender 1973; hazlett 1981; hayward & ryland 1999; reiss et al. 2003), including the arctic (barnes et al. 2007; kuklinski et al. 2008). undamaged gastropod shells of ‘‘optimal’’ weight, size and internal volume can offer good conditions for growth, reproduction (carrying eggs) and protection from desiccation, parasites, predators and other hermit crabs. it is generally considered that most hermit crab species prefer intact shells (lancaster 1988), as a limited number of studies has demonstrated (scully 1979; mcclintock 1985; wilber 1990; pechenik & lewis 2000). such shells are a limiting resource (vance 1972; kellogg 1976; hazlett 1981; lancaster 1988; but see barnes 1999) and some parts of hermit crab populations are forced to inhabit damaged shells. large empty shells are often especially scarce in the environment (lancaster 1988) and, in general, the larger the shell, the more likely it is to be broken (barnes et al. 2007). here, due to low sampling effort in some regions, the highest percentages of damaged shells (46�56%) were observed in the largest hermit crabs only at spitsbergen. predation is a major source of breakage (zuschin et al. 2003). on the basis of species lists for northern norway and svalbard (sandberg & mclaughlin 1998; gulliksen et al. 1999; gulliksen & svensen 2004; moen & svensen 2004; palerud et al. 2004), we can assume that the predation rates of shell-breaking and boring organisms (mammals, octopi, crabs, fish, gastropods, polychaetes) are similar in the studied regions. the proportion of damaged shells between northern norway (31�34%), spitsbergen (41%) and the svalbard bank (only 12%) is most likely related to the hydrodynamic regimes of those regions. high wave action in shallow waters and the rocky shores of spitsbergen and northern norway (pk, unpubl. data) results in higher abrasion and destruction of shells than in deeper offshore, relatively calmer svalbard bank. hermit crabs at their northernmost range p. balazy et al. 12 (page number not for citation purpose) citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 acknowledgements the authors wish to thank jakub beszczynski for his underwater assistance, joanna pardus (io pan) for map preparation and two anonymous reviewers for their effort in improving the paper. the project was funded by the national science centre on the basis of decision dec2011/01/n/nz8/04493 (pb). pk would like to acknowledge the funds (2022/ltsmp/2011/0) from the polish ministry of science and higher education which enabled the completion of the study. we also acknowledge the antoni dębski scholarship granted by the polish society of hyperbaric medicine and technology (ptmith) to pb. references abele l.g. 1974. species diversity of decapod crustaceans in marine habitats. ecology 55, 156�161. abrams p.a. 1980. resource partitioning and interspecific competition in a tropical hermit crab community. ecology 46, 365�379. ayres-peres l. & mantelatto f.l. 2008. patterns of distribution of the hermit crab loxopagurus loxochelis (moreira, 1901) (decapoda, diogenidae) in two coastal areas of southern brazil. revista de biologı́a marina y oceanografı́a 43, 399�411. bach c., harlett b. & rittschof d. 1976. effect of interspecific competition on fitness of the hermit crab clibanarius tricolor. ecology 57, 579�586. bach c.e. & hazlett b.a. 2009. shell shape affects movement patterns and microhabitat distribution in the hermit crabs calcinus elegans, c. laevimanus and c. latens. journal of experimental marine biology and ecology 382, 27�33. balazy p. & kuklinski p. 2013. mobile hard substrata*an additional biodiversity source in a high latitude shallow subtidal system. estuarine, coastal and shelf science 119, 153�161. barnes d.k.a. 1997. ecology of tropical hermit crabs at quirimba island, mozambique: distribution, abundance and activity. marine ecology progress series 154, 133�142. barnes d.k.a. 1999. ecology of tropical hermit crabs at quirimba island, mozambique: shell characteristics and utilization. marine ecology progress series 183, 241�251. barnes d.k.a. & de grave s. 2000. ecology of tropical hermit crabs at quirimba island, mozambique: niche width and resource allocation. marine ecology progress series 206, 171�179. barnes d.k.a. & kukliński p. 2005. low colonisation on artificial substrata in arctic spitsbergen. polar biology 29, 65�69. barnes d.k.a., kuklinski p. & włodarska-kowalczuk m. 2007. richness, abundance and shell use of subarctic and arctic hermit crabs. marine biology 152, 1133�1142. bell j.j. 2005. influence of occupant microhabitat on the composition of encrusting communities on gastropod shells. marine biology 147, 653�661. berge j., johnsen g., nilsen f., gulliksen b. & slagstad d. 2005. ocean temperature oscillations enable reappearance of blue mussels mytilus edulis in svalbard after a 1000 year absence. marine ecology progress series 303, 167�175. berge j., renaud p., eiane k., gulliksen b., cottier f., varpe o. & brattegard t. 2009. changes in the decapod fauna of an arctic fjord during the last 100 years (1908�2007). polar biology 32, 953�961. bertness m.d. 1981a. the influence of shell-type on hermit crab growth rate and clutch size (decapoda, anomura). crustaceana 40, 197�205. birula a. 1907. zoologische ergebnisse der russischen expedition nach spitzbergen. crustacea�decapoda. (zoological results of the russian expedition to spitsbergen. crustacea�decapoda.) annuairedu musée zoologique de l’académie impériale des sciences de st. pétersbourg 11, 1�68. bookhout c.g. 1964. salinity effects on larval development of pagurus bernhardus (l.) reared in the laboratory. ophelia 1, 275�294. bouchet p. & waren a. 1985. revision of the northeast atlantic bathyal and abyssal neogastropoda excluding turridae (mollusca, gastropoda). bolletino malacologico suppl. 1, 123�296. brattegard t. & holthe t. (eds.) 2001. distribution of marine, benthic macroorganisms in norway. a tabulated catalogue. research report 2001�3. trondheim: directorate for nature management. chapelle g. & peck l.s. 1999. polar gigantism dictated by oxygen availability. nature 399, 114�115. chapelle g. & peck l.s. 2004. amphipod crustacean size spectra: new insights in the relationship between size and oxygen. oikos 106, 167�175. christiansen m.e. & christiansen b.o. 1962. the crustacea decapoda of isfjorden: a comparison with the swedish spitsbergen expedition in 1908. acta scientia 19. tromsø, norway: tromsø, museum. clarke k.r. & gorley r.n. 2001. primer v6: user manual/ tutorial. plymouth: primer-e. core writing team, pachauri r.k. & reisinger a. (eds.) 2007. climate change 2007: synthesis report. a report of the intergovernmental panel on climate change. geneva: intergovernmental panel on climate change. davenport j. 1972. volume changes shown by some littoral anomuran crustacea. journal of the marine biological association of the united kingdom 52, 863. dawirs r.r. 1979. effects of temperature and salinity on larval development of pagurus bernhardus (decapoda, paguridae). marine ecology progress series 1, 323�329. dawirs r.r. 1981. elemental composition (c, n, h) and energy in the development of pagurus bernhardus (decapoda: paguridae) megalopa. marne biology 64, 117�123. dawson t.p., jackson s.t., house j.i., prentice i.c. & mace g.m. 2011. beyond predictions: biodiversity conservation in a changing climate. science 332, 53�58. duarte c.m., agusti s., wassmann p., arrieta j.m., alcaraz m., coello a., marbà n., hendriks i.e., holding j., p. balazy et al. hermit crabs at their northernmost range citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 13 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 garcı́a-zarandona i., kritzberg e. & vaqué d. 2012. tipping elements in the arctic marine ecosystem. ambio 41, 44�55. duris z. 1995. decapod crustaceans collected in norwegian and spitsbergen waters during the summer cruise of the r/v oceania, 1995. in j. repelewska-pękalowa & k. pękala (eds.): spitsbergen geographical expeditions. polar session. problems of the contemporaneous and pleistocene periglacial zone. pp. 128�132. lublin, poland: institute of earth sciences, maria curie-skłodoska university. elverhøi a., lonne o. & seland r. 1983. glaciomarine sedimentation in a modern fjord environment, spitsbergen. polar research 1, 127�150. elverhøi a. & solheim a. 1983. the physical environment*western barents sea. 1:1500000, sheet a: surface sediment distribution. norsk polarinstitutt skrifter 179a. tromsø: norwegian polar institute. elwood r.w., mark n. & dick j.t.a. 1995. consequences of shell-species preferences for female reproduction success in the hermit crab pagurus bernhardus. marine biology 123, 431�434. elwood r.w., mcclean a. & webb l. 1979. the development of shell preferences by the hermit crab pagurus bernhardus. animal behaviour 27, 940�946. eriksson s., evans s. & tallmark b. 1975. on the co-existence of scavengers on shallow, sandy bottoms of gullmar fjord (sweden): adaptations to substratum, temperature and salinity. zoon 3, 65�70. falk-petersen i.b., kanapathippilai p., primicerio r. & hansen t.k. 2010. size, locality and seasonally related feeding preferences of common wolffish (anarhichas lupus l.) from north-norwegian waters. marine biology research 6, 201�212. fay f.h. & burns j.j. 1988. maximal feeding depth of walruses. arctic 41, 239�240. fransozo a., bertini g., braga a.a. & negreiros-fransozo m.l. 2007. ecological aspects of hermit crabs (crustacea, anomura, paguroidea) off the northern coast of são paulo state, brazil. aquatic ecology 42, 437�448. fransozo a., mantelatto f.l.m., bertini g., fernandes-goes l.c. & martinelli j.m. 1998. distribution and assemblages of anomuran crustaceans in ubatuba bay, north coast of sao paulo state, brazil. acta biologica venezuelica 18, 17�25. gerlach s.a., ekstrøm d.k. & eckardt p.b. 1976. filter feeding in the hermit crab. oecologia 24, 257�264. greenwood j.g. 1972. the mouthparts and feeding behaviour of two species of hermit crabs. journal of natural history 6, 325�337. gulliksen b., palerud r., brattegard t. & sneli j. (eds.) 1999. distribution of marine benthic macro-organisms at svalbard (including bear island) and jan mayen. research report for dn 1999�4. trondheim: directorate for nature management. gulliksen b. & svensen e. 2004. svalbard and life in polar oceans. kristiansund, norway: kom publishing. harms j. 1992. larval development and delayed metamorphosis in the hermit crab cllbanarius erythropus (latrielle) (crustacea, diogenidae). journal of experimental marine biology and ecology 156, 151�160. harvey a. 1996. delayed metamorphosis in florida hermit crabs: multiple cues and constraints (crustacea: decapoda: paguridae and diogenidae). marine ecology progress series 141, 27�36. hayward p.j. & ryland j.s. (eds.) 1999. the marine fauna of the british isles and north-west europe. vol. 1: introduction and protozoans to arthropods. oxford: oxford university press. hazlett b.a. 1981. the behavioural ecology of hermit crabs. annual review of ecology, evolution, and systematics 12, 1�22. heegaard p.e. 1941. decapod crustaceans. in m. degerbel (ed.): the zoology of east greenland. meddelelser om grønland 121. pp. 1�72. copenhagen: commission for scientific investigations in greenland. henrich r., freiwald a., bickert t. & schafer p. 1997. evolution of an arctic open-shelf carbonate platform, spitsbergen bank (barents sea). in n.p. james & j.a.d. clarke (eds.): cool-water carbonates. pp. 163�181. tulsa: society for sedimentary geology. hop h., pearson t., hegseth e.n., kovacs k.m., wiencke c., kwasniewski s., eiane k., mehlum f., gulliksen b., włodarska-kowalczuk m., lydersen c., węsławski j.m., cochrane s., gabrielsen g.w., leakey r.j.g., lønne o.j., zajaczkowski m., falk-petersen s., kendall m., wängberg s.a., bischof k., voronkov a.y., kovaltchouk n.a., wiktor j., poltermann m., di prisco g., papucci c. & gerland s. 2002. the marine ecosystem of kongsfjorden, svalbard. polar research 21, 167�208. høsæter t. 1986. an annotated check-list of marine molluscs of the norwegian coast and adjacent waters. sarsia 71, 73�145. hurlbert s.h. 1971. the non-concept of species diversity; a critique and alternative parameters. ecology 52, 577�586. ingle r.w. 1993. hermit crabs of the northeastern atlantic ocean and the mediterranean sea: an illustrated key. london: chapman & hall. jackson h.g. 1913. eupagurus. liverpool marine biology committee memoirs 21, 1�79. jackson n.w. & elwood r.w. 1990. interrupting an assessment process to probe changes in the motivational state. animal behaviour 39, 1068�1077. jakubas d., głuchowska m., wojczulanis-jakubas k., karnovsky n., keslinka l., kidawa d., walkusz w., boehnke r., cisek m., kwaśniewski s. & lech stempniewicz l. 2011. foraging effort does not influence body condition and stress level in little auks. marine ecology progress series 432, 277�290. jensen k. & bender k. 1973. invertebrates associated with snail shells inhabited by pagurus bernhardus (l.) (decapoda). ophelia 10, 185�192. jones c.g., lawton j.h. & shachak m. 1994. organisms as ecosystem engineers. oikos 69, 373�386. jones c.g., lawton j.h. & shachak m. 1997. positive and negative effects of organisms as physical ecosystem engineers. ecology 78, 1946�1957. kaczmarek h., włodarska-kowalczuk m., legeżyńska j. & zajaczkowski m. 2005. shallow sublittoral macrozoobenthos in kongsfjord, west spitsbergen, svalbard. polish polar research 26, 137�155. kędra m., renaud p.e., andrade h., goszczko i. & ambrose w.g. 2013. benthic community structure, diversity, and hermit crabs at their northernmost range p. balazy et al. 14 (page number not for citation purpose) citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 productivity in the shallow barents sea bank (svalbard bank). marine biology 160, 805�819. kędra m., włodarska-kowalczuk m. & węsławski j.m. 2010. decadal change in soft-bottom community structure in high arctic fjord (kongsfjord, svalbard). polar biology 33, 1�11. kellogg c.w. 1976. gastropod shells: a potentially limiting resource for hermit crabs. journal of experimental marine biology and ecology 22, 101�111. kuklinski p., barnes d.k.a. & włodarska-kowalczuk m. 2008. gastropods shells, hermit crabs and arctic bryozoan richness. in s.j. hageman et al. (eds.): bryozoan research 2007: proceedings of the 14th international bryozoology association conference, boone, north carolina, july 1�8, 2007. virginia museum of natural history special publication 15. pp. 93�100. martinsville, va: virginia museum of natural history. kwasniewski s., gluchowska m., jakubas d., wojczulanisjakubas k., walkusz w., karnovsky n., blachowiak-samolyk k., cisek m. & stempniewicz l. 2010. the impact of different hydrographic conditions and zooplankton communities on provisioning little auks along the west coast of spitsbergen. progress in oceanography 87, 72�82. kwasniewski s., gluchowska m., walkusz w., karnovsky n.j., jakubas d., wojczulanis-jakubas k., harding a.m.a., goszczko i., cisek m., beszczynska-möller a., walczowski w., węsławski j.m. & stempniewicz l. 2012. interannual changes in zooplankton on the west spitsbergen shelf in relation to hydrography and their consequences for the diet of planktivorous seabirds. ices journal of marine science 69, 890�901. lancaster i. 1988. pagurus bernhardus (l.)*an introduction to the natural history of hermit crabs. field studies 7, 189�238. lefauconnier b., hagen j.o. & rudant j.p. 1994. flow speed and calving rate of kongsbreen glacier, 708n spitsbergen, svalbard, using spot images. polar research 13, 59�66. lindley j.a. 1998. diversity, biomass and production of decapod crustacean larvae in a changing environment. invertebrate reproduction & development 33, 209�219. linnane a., ball b., munday b., browne r. & mercer j.p. 2002. faunal description of an irish cobble site using airlift suction sampling. proceedings of the royal irish academy section b 103, 41�48. loeng h. 1991. features of the physical oceanographic conditions of the barents sea. polar research 10, 5�18. lydersen c., gjertz i. & węsławski j.m. 1989. stomach contents of autumn-feeding marine vertebrates from hornsund, svalbard. polar record 25, 107�114. macpherson e. 1971. the marine mollusca of arctic canada. publications in biological oceanography 3, 149. magdziarz k. 1984. rozmieszczenie decapoda w fjordzie hornsund, spitsbergen. (distribution of decapoda in hornsund fjord, spitsbergen.) msc thesis, university of gdansk. mcclintock t.s. 1985. effects of shell condition and size upon the shell choice behavior of a hermit crab. journal of experimental marine biology and ecology 88, 271�285. mclean r. 1983. gastropod shells: a dynamic resource that helps shape benthic community structure. journal of experimental marine biology and ecology 69, 151�174. moen f.e. & svensen e. 2004. marine fish & invertebrates of northern europe. kristiansund, norway: kom publishing. moksnes p.o. 2002. the relative importance of habitat-specific settlement, predation and juvenile dispersal for distribution and abundance of young juvenile shore crabs carcinus maenas l. journal of experimental marine biology and ecology 271, 41�73. nammco (north atlantic marine mammal commission). 1997. report of the scientific committee. nammco annual report 1996. p. 166. tromsø, norway: nammco. palerud r., gulliksen b., brattegard t., sneli j.a. & vader w. 2004. the marine macro-organisms in svalbard waters. in p. prestrud et al. (eds.): norsk polarinstitutt skrifter 201. a catalogue of the terrestrial and marine animals of svalbard. pp. 5�57. tromsø: norwegian polar institute. pallas a., garcia-calvo b., corgos a., bernardez c. & freire j. 2006. distribution and habitat use patterns of benthic decapod crustaceans in shallow waters: a comparative approach. marine ecology progress series 324, 173�184. pechenik j.a. & lewis s. 2000. avoidance of drilled gastropod shells by the hermit crab pagurus longicarpus at nahant, massachusetts. journal of experimental marine biology and ecology 253, 17�32. peura j.f., lovvorn j.r., north c.a. & kolts j.m. 2013. hermit crab population structure and association with gastropod shells in the northern bering sea. journal of experimental marine biology and ecology 449, 10�16. reiss h., knauper s. & kroncke i. 2003. invertebrate associations with gastropod shells inhabited by pagurus bernhardus (paguridae) secondary hard substrate increasing biodiversity in north sea soft-bottom communities. sarsia 88, 404�415. renaud p.e., carroll m.l. & ambrose w.g.j. 2008. effects of global warming on arctic sea-floor communities and its consequences for higher trophic levels. in c.m. duarte (ed.): impacts of global warming on polar ecosystems. pp. 141�177. bilbao: fundación bbva. renaud p.e., włodarska-kowalczuk m., trannum h., holte b., węsławski j.m., cochrane s., dahle s. & gulliksen b. 2007. multidecadal stability of benthic community structure in a high-arctic glacial fjord (van mijenfjord, spitsbergen). polar biology 30, 295�305. roberts m.h. 1971. larval development of pagurus longicarpus say reared in the laboratory. ii. effects of reduced salinity on larval development. the biological bulletin 140, 104�116. robinson m. & tully o. 2000. spatial variability in decapod community structure and recruitment in sub-tidal habitats. marine ecology progress series 191, 133�141. roy k., jablonski d. & valentine j.w. 1996. higher taxa in biodiversity studies: patterns from eastern pacific marine molluscs. philosophical transactions of the royal society b 351, 1605�1613. roy k., jablonski d., valentine j.w. & rosenberg g. 1998. marine latitudinal diversity gradients: tests of causal hypotheses. p. balazy et al. hermit crabs at their northernmost range citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 15 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 proceedings of the national academy of sciences of the united states of america 95, 3699�3702. sakshaug e., johnsen g., kristiansen s., von quillfeldt c., rey f., slagstad d. & thingstad f. 2009. phytoplankton and primary production. in e. sakshaug et al. (eds.): ecosystem barents sea. trondheim: tapir academic press. samuelsen t.j. 1970. the biology of six species of anomura (crustacea, decapoda) from raunefjorden, western norway. sarsia 45, 25�52. sandberg l. & mclaughlin p.a. 1998. crustacea, decapoda, paguridea. marine invertebrates of scandinavia 10. oslo: scandinavian university press. sandford f. 2003. population dynamics and epibiont associations of hermit crabs (crustacea: decapoda: paguroidea) on dog island, florida. memoirs of museum victoria 60, 45�52. scully e.p. 1979. the effects of gastropod shell availability and habitat characteristics on shell utilization the intertidal hermit crab pagurus longicarpus say. journal of experimental marine biology and ecology 37, 139�152. selbie c.m. 1921. the decapoda reptantia of the coasts of ireland. part ii: paguridea. ireland fisheries branch, scientific investigations 1, 1�68. sokolov v. 2006. zoogeography of decapod crustaceans in the euro-asiatic seas of arctic region. paper presented at the international council for the exploration of the sea annual science conference, theme session d. 19�23 september, maastricht, netherlands. squires h.j., ennis g. & dawe g. 1993. on biology of two sympatric species of hermit crab at st. chads, newfoundland. nafo scientific council studies 34, 7�17. stachowitsch m. 1977. the hermit crab micro biocenosis*the role of mobile secondary hard bottom elements in a north adriatic benthic community. in b.f. keegan (ed.): biology of benthic organisms. proceedings of the european symposium in marine biology. pp. 549�558. oxford: pergamon press. stelle m.a. 1999. effects of shelter and predators on reef fishes. journal of experimental marine biology and ecology 233, 65�79. svendsen h., beszczynska-møller a., hagen j.o., lefauconnier b., tverberg v., gerland s., ørbæk j.b., bischof k., papucci c., zajaczkowski m., azzolini r., bruland o., wiencke c., winther j.-g. & dallmann w. 2002. the physical environment of kongsfjorden�krossfjorden, and arctic fjord system in svalbard. polar research 21, 133�166. swerpel s. 1985. the hornsund fiord: water masses. polish polar research 6, 475�496. thorson g. 1944. the zoology of east greenland. marine gastropoda prosobranchia. meddelelser om grønland 121. copenhagen: commission for scientific investigations in greenland. thorson g. 1946. reproduction and larval development of danish marine bottom invertebrates. meddelelser fra kommissionen for danmarks fiskeriog havundersøgelser serie plankton 4. copenhagen: commission for danish fishery and marine research. tricarico e., bertocchi s., brusconi s., antonio l. & gherardi f. 2009. shell recruitment in the mediterranean hermit crab clibanarius erythropus. journal of experimental marine biology and ecology 381, 42�46. vance r.r. 1972. competition and mechanism of coexistence in three sympatric species of intertidal hermit crabs. ecology 53, 1062�1074. wahle r.a. & steneck r.s. 1991. recruitment habitats and nursery grounds of the american lobster homarus americanus: a demographic bottleneck? marine ecology progress series 69, 231�243. walczowski w. & piechura j. 2006. new evidence of warming propagating toward the arctic ocean. geophysical research letters 33, l12601, doi: 10.1029/2006gl025872. walczowski w., piechura j., goszczko i. & wieczorek p. 2012. changes in atlantic water properties: an important factor in the european arctic marine climate. ices journal of marine science 69, 864�869. wang m. & overland j.e. 2012. a sea ice free summer arctic within 30 years: an update from cmip5 models. geophysical research letters 39, l18501, doi: 10.1029/2012gl052868. warner g.f. 1977. the biology of crabs. london: elek. warwick r.m., emblow c., feral j.p., hummel h., van avesaath p. & heip c. 2003. european marine biodiversity research sites: report of the european concerted action: biomare implementation and networking of large scale, long term marine biodiversity research in europe. yerseke, netherlands: centre for estuarine and marine research, ecology netherlands institute for ecological research. warwick r.m. & light j. 2002. death assemblages of molluscs on st martin’s flats, isles of scilly: a surrogate for regional biodiversity? biodiversity & conservation 11, 99�112. wassmann p., duarte c.m., agusti s. & sejr m.k. 2011. footprints of climate change in the arctic marine ecosystem. global change biology 17, 1235�1249. węsławski j.m. 1987. distribution of decapoda (crustacea) in south spitsbergen coastal waters with remarks on their ecology and breeding biology. polish polar research 8, 121�134. węsławski j.m., kendall m., włodarska-kowalczuk m., iken k., kędra m., legeżyńska j. & sejr m.k. 2011. climate change effects on arctic fjord and coastal macrobenthic diversity*observations and predictions. marine biodiversity 41, 71�85. węsławski j.m., koszteyn j., kwaśniewski s., stempniewicz l. & malinga m. 1999. summer food resources of the little auk, alle alle (l.) in the european arctic seas. polish polar research 20, 387�403. węsławski j.m., kwasniewski s. & wiktor j. 1991. winter in a svalbard fjord ecosystem. arctic 44, 115�123. węsławski j.m., stempniewicz l., mehlum f. & kwasniewski s. 1999. summer feeding strategy of the little auk (alle alle) from bjornoya, barents sea. polar biology 21, 129�134. węsławski j.m., wiktor j., jr. & kotwicki l. 2010. increase in biodiversity in the arctic rocky littoral, sorkappland, svalbard, after 20 years of climate warming. marine biodiversity 40, 123�130. hermit crabs at their northernmost range p. balazy et al. 16 (page number not for citation purpose) citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 węsławski j.m., wiktor j., zajaczkowski m. & swerpel s. 1993. intertidal zone of svalbard 1. macroorganisms distribution and biomass. polar biology 13, 73�108. węsławski j.m., zajączkowski m., kwaśniewski s., jezierski j. & moskal w. 1988. seasonality in an arctic fjord ecosystem: hornsund, spitsbergen. polar research 6, 185�189. węsławski j.m., zajączkowski m., wiktor j. & szymelfenig m. 1997. intertidal zone of svalbard 3. littoral of a subarctic, oceanic island: bjornoya. polar biology 18, 45�52. weydmann a., søreide j.e., kwasniewski s., leu e., falkpetersen s. & berge j. 2013. ice-related seasonality in zooplankton community composition in a high arctic fjord. journal of plankton research 35, 831�842. wilber t.p. 1990. influence of size, species and damage on shell selection by the hermit crab pagurus longicarpus. marine biology 104, 31�39. williams j.d. & mcdermot j.j. 2004. hermit crab biocoenoses: a worldwide review of the diversity and natural history of hermit crab associates. journal of experimental marine biology and ecology 305, 1�128. winkelmann d. & knies j. 2005. recent distribution and accumulation of organic carbon on the continental margin west off spitsbergen. geochemistry, geophysics, geosystems 6, q09012, doi: 10.1029/2005gc000916. włodarska-kowalczuk m. 2007. molluscs in kongsfjorden (spitsbergen, svalbard): a species list and patterns of distribution and diversity. polar research 26, 48�63. włodarska-kowalczuk m., kendall m., węsławski j.m., klages m. & soltwedel t. 2004. depth gradients of benthic standing stock and diversity on the continental margin at a highlatitude ice-free site (off spitsbergen, 798n). deep-sea research part i 51, 1903�1914. włodarska-kowalczuk m., pearson t.h. & kendall m.a. 2005. benthic response to chronic natural physical disturbance by glacial sedimentation in an arctic fiord. marine ecology progress series 303, 31�34. włodarska-kowalczuk m., szymelfenig m. & zajaczkowski m. 2007. dynamic sedimentary environments of an arctic glacier-fed river estuary (adventfjorden, svalbard). ii. meioand macrobenthic fauna. estuarine, coastal and shelf science 74, 274�284. włodarska-kowalczuk m., węslawski j.m. & kotwicki l. 1998. spitsbergen glacial bays macrobenthos*a comparative study. polar biology 20, 66�73. yoshino k., goshima s. & nakao s. 2002. temporal reproductive patterns within a breeding season of the hermit crab pagurus filholi: effects of crab size and shell species. marine biology 141, 1069�1075. zajączkowski m. & włodarska-kowalczuk m. 2007. dynamic sedimentary environments of an arctic glacier-fed river estuary (adventfjorden, svalbard). i. flux, deposition and dynamics of the sediment. estuarine, coastal and shelf science 74, 285�296. zuschin m. & pille w.e. 2007. gastropod shells recycled*an example from a rocky tidal flat in the northern red sea. lethaia 30, 127�134. zuschin m., stachowitsch m. & stanton r.j. 2003. patterns and processes of shell fragmentation in modern and ancient marine environments. earth-science reviews 63, 33�82. p. balazy et al. hermit crabs at their northernmost range citation: polar research 2015, 34, 21412, http://dx.doi.org/10.3402/polar.v34.21412 17 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21412 http://dx.doi.org/10.3402/polar.v34.21412 no job name b o o k r e v i e w por_176 229..231 review of recent mammals of alaska, by s.o. macdonald and j.a. cook (2010). fairbanks: university of alaska press. 399 pp. isbn 1602230722. billed as a summary monograph, this book is more precisely a catalogue of all mammals that have been documented in alaska during the past 10 000 years, fronted by an introduction to mammalian collections in alaska, and a short overview of alaskan biogeography, and summarized in a set of appendices. in between these two segments are 116 1–2-page species accounts, each of which includes a brief summary of the taxonomy, distribution, abundance and status. in creating this text, the authors have summarized a great deal of detailed information gleaned from a thorough combing of both peerreviewed and grey literature. however, the aim of the book is centred less around describing the basic biology and ecology of alaskan mammals, than on introducing the readers to the archived specimens that exist in museum collections. this focus reflects the training and expertise of the two authors, both of whom have spent their careers affiliated with natural history collections: s.o. macdonald worked as a curator at the at the university of alaska museum (uam) from 1979 to 1984, and is now curator in the mammals division of the museum of southwestern biology (msb) at the university of new mexico, whereas j.a. cook was the curator of mammals at uam from 1990 to 2001, and now fills that role at msb. cook, macdonald and their students have conducted extensive field collections in alaska, and throughout their careers have advocated strongly that natural history collections are valuable research tools. this book serves as a summary of their work, and as a plea for continued efforts in these areas. the focus on collections and their worth begins in the introduction, with a review of the history of mammal collections in the state, a review of the various uses to which collections can be put and a few brief summaries of studies that were either hindered by an incomplete understanding of the diversity of species within an area or enabled by the existence of robust collections. these mini-reviews serve as examples of the value of natural history collections, but because the emphasis is on the use of collections, and not the results of the studies, they do not provide the reader with much insight into the biology or ecology of alaskan mammals. the emphasis is also apparent in the individual species accounts, where the range maps for each species indicate alaskan collection locations much more clearly than species distribution. although collections are certainly valuable, and the authors have gone to significant effort to provide information on the museums housing all known alaskan specimens—and have thereby saved others this time and effort—i can’t help but wonder if much of this task couldn’t be accomplished through the judicious use of online databases, which, by their nature, are better able to incorporate new entries. indeed uam and msb both participate in an ongoing effort to make mammal collection data from multiple museums available and searchable online (http://arctos.database.museum/ home.cfm). the section advocating collections is followed by a brief overview of the six main regions within alaska (southeast, southcentral, central, southwest, western, and correspondence jennifer m. burns, department of biological sciences, university of alaska anchorage, 3101 science circle, cpsb 101, anchorage, ak 99508, usa. e-mail: afjmb4@uaa.alaska.edu polar research 29 2010 229–231 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 229 http://arctos.database.museum/home.cfm http://arctos.database.museum/home.cfm mailto:afjmb4@uaa.alaska.edu northern alaska). each region’s vegetative community is briefly summarized (approximately one page per region), and a listing of key mammalian taxa present in the region is included. this section is a fairly dry recounting of facts, and is one of the few sections of the text that is not adequately referenced, despite being derivative of any number of books on alaskan ecology. the few lowresolution black and white photographs included in this section add little value. in addition, as these regions reflect the alaska department of fish and game’s game management units (http://wildlife.alaska.gov/gis), rather than established ecoregions (nowacki et al. 2001), the regional species distributions presented do not provide insight into biotic factors that influence habitat selection. this is also reflected in the often terse description of the habitats of individual species (for example, beaver [castor canadensis] habitat is described as “lakes, ponds, marshes, rivers and streams” [p. 79]). data on alaska’s current (or historic) climate are not included, nor is any indication of thermal tolerances provided within the individual species accounts. thus, the interplay between climate, habitats and species distribution remains unexplored. this is notable mainly because the authors earlier argued (pp. 3, 20) that expanded collections are needed to better understand the impact of global climate change on species distributions, and yet this book does little to provide even the minimal level of detail with which to begin to make such links. throughout the text, the authors focus on what is present rather than why it is present. indeed, the existence of a single documented occurrence or specimen record from alaska appears to be the sole requirement for inclusion in this text. this odd selection criterion produces a text that treats rare vagrants (harp seal [pagophilus groenlandicus]), migrants (grey whale [eschrichtius robustus]), endemics (many of the bats), introduced species (wapati [cervus canadensis]) and common residents (black bear [ursus americanus]) equally, but that only includes extinct holocene mammals for which specimens exist within alaskan institutions (steller’s sea cow [hydrodamalis gigas], woolly mammoth [mammuthus primigenius]). the 116 species included in this comprehensive catalogue are grouped taxonomically, with alphabetical organization only present at the level of genus and species, and not among families or orders. as a result, it is difficult to page through the text to locate particular species, even with knowledge of ordinal and familiar affiliation. the individual species entries that make up the vast majority of this book each include sections on systematics (nomenclature for species and subspecies; source for the original description, type locality and museum housing the type specimen), distribution (globally and regionally), habitat (vegetative community in which species is located), status (abundance) and fossils (geological deposits in which fossils have been located). these sections have a clear alaskan focus, although data from other regions are occasionally included. although scrupulously accurate, the information under each subheading has been kept so minimal that it almost fails to convey any worthwhile data (e.g., the status of meadow jumping mice [zapus hudsonius] is “localized and sometimes abundant” [p. 82].) whereas this brevity is frequently mitigated by the copious use of relevant citations, any reader intending to use this text to learn much about the mammals of alaska will be immediately frustrated by the need to return to the library to find the source literature. conversely, information provided under the systematics and fossils categories often assumes extensive geographic and geological background, rendering these sections challenging for the lay reader. nor will the text be of much use to readers aiming to determine species range or distribution, as the range maps included with each account emphasize collection locations. statewide distributional data, if mapped at all, is often of poor quality. aside from a few pleasant line drawings by alaskan artist w.d. berry, most of the species remain un-illustrated. the text ends with an extensive and up-to-date literature section, in which often difficult to find agency and non-profit organization reports stand side by side with peer-reviewed literature. the authors are to be commended on the depth and breadth of their review. the index is similarly thorough, and makes the entire text much more accessible to the scientist and public readers. however, it is the appendices that are the true glory of this text. in a series of 12 detailed tables, the authors concisely summarize and cross-collate all the data contained within the preceding species accounts. among others, there are appendices tabulating the regional distribution and habitat preferences of the various taxa, the museums in which specimens are housed, the temporal occurrence of the species, and the history and fate of the introductions of non-native species. these tables do almost as thorough a job at conveying the information as the main text, and are likely to be much more useful to the readers of this book, as they remove the need to page through multiple accounts to discover the key facts. where necessary, the appendices are equally well referenced as the rest of the book. the fact that i found the most compelling information of the book contained in the appendices highlights my puzzlement over the audience at which this text is aimed. hobbyists and lay people who may find this book in museum bookstores are unlikely to be greatly interested in the locations of scientific collections or the details of taxonomic nomenclature, and would probably prefer book review polar research 29 2010 229–231 © 2010 the author, journal compilation © 2010 blackwell publishing ltd230 http://wildlife.alaska.gov/gis more information on each species to be included here, rather than only referenced. for these readers, this dry text fails to be a useful field guide to the mammals of alaska because of its dearth of basic biological or ecological information and the remarkable absence of photographs in the species accounts. however, aside from the appendices, the text also fails as a reference guide for scientists working on alaska’s mammalian fauna, as the derivative nature of the information provided within each species’ summary is unlikely to provide any new information to active scientists. as one example, all pinniped and cetacean distributional data reported here are obtained from the national oceanic and atmospheric administration’s stock assessment report (angliss & outlaw 2007), which summarizes multiple primary studies, is available online and is updated regularly. active researchers are far more likely to refer to the most recent stock assessment report, rice (1998), and uam’s online database, rather than this book. unfortunately, despite its breadth, the shallow depth of the information contained within these pages almost guarantees that this reference will be of use only to a small subset of biogeographers and taxonomers that are not currently familiar with alaska or its mammals; neither working scientists nor the general public are likely to find this text compelling. references angliss r.p. & outlaw r.b. 2007. alaska marine mammal stock assessments, 2006. noaa technical memorandum nmfsafsc-168. seattle, wa: us department of commerce. nowacki g., spenser p., fleming m., brock t. & jorgenson t. 2001. unified ecoregions of alaska. u.s. geological survey open-file report 02-297 (map). reston, va: us geological survey. rice d.w. 1998. marine mammals of the world: systematics and distribution. lawrence, ks: society for marine mammalogy. book review polar research 29 2010 229–231 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 231 no job name survey of waste water disposal practices at antarctic research stationspor_056 298..306 fredrik gröndahl,1 johan sidenmark2 & ann thomsen1 1 dept. of industrial ecology, royal institute of technology, teknikringen 34, se 114 28, stockholm, sweden 2 swedish polar research secretariat, royal swedish academy of sciences, lilla frescativägen 4, se 104 05 stockholm, sweden abstract to inform the future practices to be employed for handling waste water and grey water at the swedish antarctic station, wasa, in dronning maud land, the swedish polar research secretariat took the initiative to survey the practices of the 28 nations with stations in antarctica. a questionnaire was sent out to all members of the antarctic environment officers network during the autumn of 2005. questions were asked about the handling of waste water and grey water, the type of sewage treatment, and installation and operational costs. the response to the questionnaire was very good (79%), and the results showed that 37% of the permanent stations and 69% of the summer stations lack any form of treatment facility. when waste water and grey water containing microorganisms are released, these microorganisms can remain viable in lowtemperature antarctic conditions for prolonged periods. microorganisms may also have the potential to infect and cause disease, or become part of the gut flora of local bird and mammal populations, and fish and marine invertebrates. the results from 71 stations show that much can still be done by the 28 nations operating the 82 research stations in antarctica. the technology exists for effective waste water treatment in the challenging antarctic conditions. the use of efficient technology at all permanent antarctic research stations would greatly reduce the human impact on the pristine antarctic environment. in order to protect the antarctic environment from infectious agents introduced by humans, consideration should also be given to preventing the release of untreated waste water and grey water from the smaller summer stations. keywords antarctica; grey water; pathogens; sewage treatment; wasa station; waste water. correspondence fredrik gröndahl, dept. of industrial ecology, royal institute of technology, teknikringen 34, se 114 28, stockholm, sweden. e-mail: fgro@kth.se doi:10.1111/j.1751-8369.2008.00056.x antarctica is the most pristine continent on earth, as its remoteness, enormous size and extreme climate have left antarctica with little or no evidence of human impact over vast regions. however, increased accessibility has led to an increase in the activities and numbers of visitors to the antarctic region (international association of antarctica tour operators [iaato] 2008). the increased human presence is also leading to increased pressure on the surrounding environment, and one challenge for antarctic operations is waste management and waste disposal in these untouched areas (e.g., hughes 2003, 2004; hughes & blenkharn 2003). scientific research is a major activity in antarctica. in recent years there has been a continued growth in the number and size of stations and semi-permanent field camps. in the summer season, approximately 4000 scientists and technicians carry out research and monitoring, and in the winter the scientific community in antarctica is estimated to comprise around 1000 people (cia 2008). most of the scientific stations, semi-permanent bases and field stations are situated in coastal areas or on ice-free terrain. these areas make up only 2% of the antarctic surface (cia 2008), and are areas that are prone to disturbance and/or where the environment is slow to revert to the undisturbed state. tourism is another prominent activity, with 37 550 tourists visiting antarctica during the austral summer 2006/07, according to iaato. in addition to the tourists, approximately 22 500 tourism industry staff and crew also visited the area (iaato 2008). tourist activities are also concentrated on coastal areas, mainly on the antarctic peninsula, and take place during the austral summer, which is the most biologically sensitive period for terrestrial biota. polar research 28 2009 298–306 © 2008 the authors298 mailto:fgro@kth.se both research and tourism increase the risk of humans introducing infectious agents that are new to the antarctic flora and fauna. one output from both of these activities that poses a threat to the antarctic environment is waste generation. studies in the region have already detected well-known pathogens that may have been introduced by humans, such as salmonella enteritidis, salmonella typhimurium, campylobacter jejuni and pasteurella multocida, in both seal and bird populations (de lisle et al. 1990; olsen et al. 1996; broman et al. 2000: palmgren et al. 2000). the first findings of the enteropathogenic escherichia coli in antarctic wildlife have recently been reported in antarctic fur seals (arctocephalus gazella) (hernandez et al. 2007). all waste water produced at a research station excepting toilet waste (urine and faeces) is called grey water. most of the grey water comes from laundry, showers, sinks and washing dishes. grey water may contain fat, oil and other organic substances from cooking, residues from soap and tensides from detergents. the content of pathogens in grey water is low in comparison with toilet waste (black water). however, grey water, especially from bath/ shower and laundry, may contain pathogens such as bacteria and viruses (stenström 1996). waste water treatment is the process of removing physical, chemical and biological contaminants from waste water, and as a result it involves physical, chemical and biological processes. external and internal treatments are the two main methods available. external treatment is the most common method, and is usually performed away from the production site (e.g., a sewage treatment plant). internal methods are generally located where the waste water is produced; examples include septic tanks, biofilters and anaerobic treatment systems. the main methods used for internal water treatment are adsorption, ion exchange, membranes, extraction and vaporization (persson 2005). waste water treatment can involve three stages: primary, secondary and tertiary treatment. the primary stage removes solids such as waste, fats, oils and grease from the waste water stream. the methods used are mechanical, maceration and sedimentation. in the secondary stage, dissolved biological matter is progressively converted into a solid mass using waterborne microorganisms, and the biological solids are either disposed of or are reused (e.g., activated sludge, fluidized bed reactors, filter beds, biological aerated filters or membrane biological reactors). in the tertiary treatment, the treated water may be disinfected chemically or physically (e.g., by microfiltration, nutrient removal with biological processes or chemical precipitation, chlorine, uv light or ozone). the final effluent can then be discharged to the natural environment (persson 2005). the protocol on environmental protection to the antarctic treaty (hereafter referred to as the protocol) states that the protection of the antarctic environment, and the dependent and associated ecosystems, is in the interest of mankind as a whole (antarctic treaty secretariat 1998a). the protocol is based on the principle that protection of the antarctic environment, and the dependent and associated ecosystems, and consequently the intrinsic value of antarctica, shall be fundamental considerations in the planning and conduct of all activities in the antarctic treaty area (article 3.1). annex iii to the protocol (antarctic treaty secretariat 1998b) applies to waste disposal and waste management, and obliges all countries to apply responsible waste management principles and to develop waste management plans. article 1.2 states that “the amount of wastes produced or disposed of in the antarctic treaty area shall be reduced as far as practicable so as to minimise impact on the antarctic environment and to minimise interference with the natural values of antarctica, with scientific research and with other uses of antarctica which are consistent with the antarctic treaty”. built during the austral summer 1988/89, wasa is the main swedish station in antarctica. the station is located at 73°03′s, 13°25′w at the nunatak basen. basen is the westerly offshoot of the vestfjella mountain range, dronning maud land, and is situated 460 m a.s.l. and 120-km inland. the finnish station aboa is located 200 m from wasa. the station is only used during the austral summer seasons. the station consists of nine buildings, and normally accommodates 12–16 people, but can accommodate up to 30 people. sweden also has a small field station, svea, located at 74°35′s, 11°13′w. water consumption at wasa is on average 100 litres per person per day. grey water from wasa is transported downhill via a 100-m-long insulated and heated pipe, and is discharged to an ice-covered area below the station, where it drains into the surrounding ice and finally to the sea. a waste water treatment system was initially installed, but was decommissioned in 1996 because it did not function properly. the legal obligations from the protocol have been interpreted into practical guidelines, and can be found in the nordic environmental handbook on antarctic operations. expeditions follow specific guidelines when handling waste on the swedish station wasa and in the field. waste is recycled, separated and retrograded for appropriate disposal outside antarctica. as wasa is a small summer-only station, releasing untreated waste water and grey water into a crevasse still fulfils the obligations under the protocol. the ambition for the swedish antarctic research programme and the swedish polar research secretariat is to investigate the possibility of installing waste water survey of waste water disposal practices at antarctic research stationsf. gröndahl et al. polar research 28 2009 298–306 © 2008 the authors 299 treatment at wasa in the coming years. in order to learn from other nations and stations, the swedish polar research secretariat took the initiative for the present study. this paper investigates waste water disposal in antarctica, and presents an inventory of the existing practices at 71 antarctic research stations. materials and methods study area most antarctic stations are situated along the coastline, where accessibility is better (fig. 1). most stations are built on bare ground (e.g., mcmurdo station). some have been constructed on the permanent ice cap (e.g., amundsen-scott base, south pole) or on ice shelves (halley research station, brunt ice shelf). the swedish station wasa (no. 45 in fig. 1) and the finnish station aboa (no. 35 in fig. 1) are examples of stations located on snow-free basalt ground. by sending out a questionnaire to all 28 nations active in antarctica, information was obtained on how these other countries handle the waste water from their stations. the questionnaire was emailed to members of the antarctic environment officers network (aeon) during the autumn of 2005. the questions asked were as follows: (1) how many stations are used by your country? (2) how is waste water handled by the station/s? (3) is there a sewage treatment system in operation? if not, is such treatment being planned? (4) what type of sewage treatment system is in use? (5) how does the sewage treatment system work, and what kind of process is used? (6) does the sewage treatment system run all year around or only during expeditions? (7) does it take a long time to get the system working when an expedition arrives at the station? (8) does the sewage treatment system need a power source? (9) what are the running costs, and how much has been invested in sewage treatment? (10) is the system working satisfactorily? the information collected, together with some additional information from the council of managers of national antarctic programs (comnap 2005), was used to draw conclusions and to provide a better picture of waste water management at antarctic research stations. results there was a good response to the survey, with 22 out of 28 countries completing the questionnaire (tables 1, 2). almost two-thirds (63%) of the permanent stations have some kind of treatment system (table 2). when it comes to summer stations, however, less than one-third (31%) have a treatment system (table 2), whereas none of the field stations has any such system (table 2). altogether, the results show that less than half (48%) of all 71 stations have some sort of waste water treatment (table 2). the different waste water treatment systems used at the stations are shown in table 3. of the 63% of permanent stations that have some form of treatment system, the most common type is biological treatment, which is used by 20% of the stations. 10% of stations use macerations and another 10% use secondary treatment. two stations (5%) have septic tanks as treatment, and the fig. 1 the location of research stations in antarctica. arrows on the map indicate stations on sub-antarctic islands. the nationality of the stations is indicated in table 1. (map modified from comnap 2005, and used with permission.) survey of waste water disposal practices at antarctic research stations f. gröndahl et al. polar research 28 2009 298–306 © 2008 the authors300 ta b le 1 w as te w at e r tr e at m e n t at th e a n ta rc ti c re se ar ch st at io n s u se d b y th e 2 8 co u n tr ie s w it h ac ti vi ti e s o n th e co n ti n e n t. t h e an sw e rs ar e ta ke n fr o m th e 2 2 re sp o n se s to th e su rv e y, w h e re as fo r th e si x co u n tr ie s th at d id n o t re sp o n d , th e re le va n t d at a w e re d ra w n fr o m th e c o m n a p w e b si te (c o m n a p 2 0 0 5 ), as in d ic at e d in co lu m n 6 . s o m e o f th e fie ld st at io n s, e .g ., s w e d e n , u k an d u ru g u ay , ar e n o t lo ca te d in fi g . 1 . c o u n tr y s ta ti o n a s ta ti o n s in th e su rv e y tr e at m e n t sy st e m ty p e o f tr e at m e n t c o st a rg e n ti n a 3 , 5 , 6 , 1 7 , 2 3 , 2 5 , 2 6 , 2 8 , 2 9 , 3 2 , 3 3 , 7 3 , 7 6 ,7 7 6 p e rm an e n t st at io n s, 7 su m m e r st at io n s fo u r o f th e p e rm an e n t st at io n s. g re y w at e r re cy cl e d to b e u se d in to ile ts , b la ck w at e r tr e at e d in se p ti c ta n k, o r al lw at e r tr e at e d in b io lo g ic al tr e at m e n t p la n t. la st e q u ip m e n t $ 9 0 0 0 . a u st ra lia 2 3 , 5 2 , 5 8 , 5 9 , 6 5 , 6 6 , 6 8 3 p e rm an e n t st at io n s ye s, th o u g h o n e h as fa ile d an d is g o in g to b e re p la ce d . s e co n d ar y tr e at m e n t w it h ro ta ti n g b io fil te rs . t h e n e w p la n t w ill p ro b ab ly co st $ 2 .2 m . b e lg iu m – o n e w ill b e o p e n e d in th e se as o n 2 0 0 7 /0 8 t h e st at io n w ill h av e a p la n t. n o t co n si d e re d ye t. n o t re le va n t ye t. b ra zi l 2 0 1 p e rm an e n t st at io n ye s. p ri m ar y an d se co n d ar y tr e at m e n t. d at a fr o m c o m n a p. b u lg ar ia 2 1 1 su m m e r st at io n n o . – d at a fr o m c o m n a p. c h ile 4 , 7 , 8 , 1 0 , 1 1 , 1 4 , 2 4 , 7 5 , 7 8 3 p e rm an e n t st at io n s, 6 su m m e r st at io n 3 su m m e r st at io n s an d 1 p e rm an e n t st at io n . h as se co n d ar y tr e at m e n t. d at a fr o m c o m n a p. c h in a 1 2 , 5 7 2 p e rm an e n t st at io n s ye s. s e w ag e tr e at m e n t, b io lo g ic al tr e at m e n t. n o t an sw e re d . c ze ch r e p u b lic n o t lis te d 1 su m m e r st at io n n o . – – ec u ad o r 7 9 1 su m m e r st at io n n o in fo rm at io n . – d at a fr o m c o m n a p. fi n la n d 3 5 1 su m m e r st at io n ye s. b io lo g ic al w as te w at e r tr e at m e n t p la n t th at tr e at s g re y w at e r. n o t an sw e re d . fr an ce 6 , 3 1 , 5 1 , 6 3 , 7 2 4 p e rm an e n t st at io n s, 1 su m m e r st at io n o n e o f th e m , th e o th e r w ill in th e fu tu re . r e cy cl in g o f g re y w at e r, g re y w at e r tr e at m e n t: fo u r st ag e s o f m e m b ra n e fil tr at io n (u lt ra fil tr at io n , n an o fil tr at io n an d tw o st e p s o f re ve rs e o sm o si s) . b la ck w at e r: an ae ro b ic an d ae ro b ic d ig e st io n an d n it ri fic at io n . $ 8 4 6 0 0 0 in st al la ti o n an d e q u ip m e n t. g e rm an y 1 8 , 3 7 , 8 1 1 p e rm an e n t st at io n , 2 su m m e r st at io n s t h e p e rm an e n t st at io n h as tr e at m e n t. b io lo g ic al p la n t. n o t an sw e re d . in d ia 4 1 1 p e rm an e n t st at io n ye s. b io d ig e st o r (li q u id w as te ) an d in ci n e ra ti o n (h u m an w as te ). d at a fr o m c o m n a p. it al y 6 4 , 6 9 1 p e rm an e n t st at io n (c o n co rd ia ) ru n to g e th e r w it h fr an ce , 1 su m m e r st at io n ye s, su m m e r st at io n , p e rm an e n t st at io n w ill g e t tr e at m e n t in tw o ye ar s. s e w ag e tr e at m e n t p la n t. d at a fr o m c o m n a p. ja p an 4 6 , 4 7 , 4 8 , 4 9 2 p e rm an e n t st at io n s, 2 su m m e r st at io n s o n e o f th e m . b io lo g ic al se w ag e tr e at m e n t in ta n ks b e fo re d is p o sa lt o th e se a. n o t an sw e re d . k o re a 1 6 1 p e rm an e n t st at io n ye s. a e ra ti o n , ch e m ic al , b io lo g ic al tr e at m e n t an d th e n d is ch ar g e to se a. n o t an sw e re d . n e w ze al an d 7 1 1 p e rm an e n t st at io n ye s. b io lo g ic al tr e at m e n t. $ 2 4 2 0 0 0 fo r in st al la ti o n an d $ 9 5 0 0 p e r ye ar . survey of waste water disposal practices at antarctic research stationsf. gröndahl et al. polar research 28 2009 298–306 © 2008 the authors 301 ta b le 1 c o n ti n u e d c o u n tr y s ta ti o n a s ta ti o n s in th e su rv e y tr e at m e n t sy st e m ty p e o f tr e at m e n t c o st n o rw ay 3 9 , 4 0 1 p e rm an e n t st at io n , 1 fie ld st at io n ye s, fa e ce s ar e co lle ct e d an d tr an sp o rt e d o u t o f a n ta rc ti ca . w as te w at e r is tr e at e d an d re le as e d to th e g ro u n d . in ci n e ra to r to ile ts ar e u se d an d th e re fo re n o b la ck w at e r. to o so o n to sa y b e ca u se it o p e n e d th is se as o n (2 0 0 4 /0 5 ). p e ru 2 2 1 p e rm an e n t st at io n n o , b u t is g e tt in g si m ila r sy st e m to n e w ze al an d . b io lo g ic al tr e at m e n t. – p o la n d 1 9 1 p e rm an e n t st at io n c o lle ct e d in ta n k. n o t an sw e re d . n o t an sw e re d . r u ss ia 1 3 , 4 4 , 5 0 , 5 4 , 5 5 , 5 6 , 6 1 , 6 2 5 p e rm an e n t st at io n s, 3 su m m e r st at io n s o n e o f th e m , b u t th e y ar e p la n n in g to g e t it fo r th e o th e rs . d e st ru ct io n o f m ic ro b io ta b y e le ct ri c fie ld an d d is in fe ct io n b e fo re re le as e to se a. t h e o th e r d is ch ar g e s d ir e ct ly to se a e xc e p t v o st o k, w h ic h d is ch ar g e s to an ic e p it . u n it co st $ 6 0 0 0 0 p lu s $ 3 0 0 0 ye ar ly . s o u th a fr ic a 3 6 , 3 8 , 4 2 , 4 3 1 p e rm an e n t st at io n , 3 su m m e r st at io n s ye s. b io fil te r: ro ta ti n g b io lo g ic al co n ta ct o rs p u ri fic at io n p la n t. c o st fo r p la n t $ 2 3 1 0 0 0 p lu s $ 8 0 0 ye ar ly . s p ai n 9 , 8 0 2 su m m e r st at io n s ye s. tr e at e d in se p ti c ta n k; o p e ra ti ve in 1 – 2 d ay s. n o t an sw e re d . s w e d e n 4 5 1 su m m e r st at io n , 1 fie ld st at io n n o , b u t a n e w tr e at m e n t sy st e m fo r g re y w at e r at th e su m m e r st at io n s is co m in g . t h e re ar e d ry to ile ts . to o so o n to sa y. u kr ai n e 1 1 p e rm an e n t st at io n n o . d is ch ar g e b y co n st an tl y ci rc u la ti n g se a w at e r. el e ct ri c p o w e r o n ly . u n it e d k in g d o m 2 7 , 3 0 , 3 4 , 7 4 , 8 2 4 p e rm an e n t st at io n s, 1 su m m e r st at io n , 2 fie ld st at io n s o n e h as a tr e at m e n t p la n t, o n e h as m ac e ra ti o n an d o n e p e rm an e n t h as in ci n e ra ti o n to ile ts . p ri m ar y tr e at m e n t (s cr e e n in g an d se tt lin g ), se co n d ar y (b io lo g ic al ae ra ti o n ) an d te rt ia ry (u v st e ri liz at io n ). eq u ip m e n t $ 1 4 7 0 0 0 in 1 9 9 9 , b u t sh ip p in g , co n st ru ct io n an d ru n n in g n o t in cl u d e d . u n it e d s ta te s 2 , 7 0 , 6 0 3 p e rm an e n t st at io n s ye s, tw o o f th e m . c o n si d e ra ti o n fo r al l in th e fu tu re . s e w ag e tr e at m e n t p la n t an d th e o th e rs h av e m ac e ra ti o n b e fo re d is p o sa li n to o ce an . to b u ild a w as te w at e r tr e at m e n t p la n t co st s $ 1 .2 m an d ru n n in g w it h o n e o p e ra to r w it h m in im al tr ai n in g co st s $ 1 2 5 0 0 0 ye ar ly . u ru g u ay 1 5 1 p e rm an e n t st at io n , 1 fie ld st at io n ye s. tr e at e d in se p ti c ch am b e rs , an d th e n st o re d in d ru m s fo r re m o va lo u t o f a n ta rc ti ca . p ri m ar y tr e at m e n ts ta ke p la ce in th e se p ti c ta n k. m ac h in e co st s $ 6 0 0 an d ru n n in g co st s $ 9 0 0 . to ta lf o r al l2 8 co u n tr ie s 4 1 p e rm an e n t st at io n s, 2 6 su m m e r st at io n s an d 4 fie ld st at io n s 2 6 o f 4 1 p e rm an e n t st at io n s, 8 o f 2 6 su m m e r st at io n s, 0 fie ld st at io n . a t h e st at io n n u m b e r co rr e sp o n d s to th e n u m b e rs sh o w n in fi g . 1 . survey of waste water disposal practices at antarctic research stations f. gröndahl et al. polar research 28 2009 298–306 © 2008 the authors302 other methods are used at one station each. of the 31% of summer stations that have some form of treatment system, septic tanks and secondary treatment are used by 23% of the stations. biological treatment and sewage treatment are only used by two stations (5%). some of the responses to the questionnaire are not shown in table 1, for example the important question 10: is the system working satisfactorily? ten countries responded affirmatively (argentina, germany, korea, poland, ukraine, uruguay, china, the uk, the us and spain). three countries (france, russia and norway) stated that their system was too new for any conclusions to be drawn about its functionality. four countries reported problems (australia, japan, new zealand and south africa). australia has two stations where the treatment works well, but the station davis is having problems. both south africa and new zealand reported that it is difficult to get a high quality of effluent during periods of high influx of people to the stations during the summer season. a more detailed description of the answers to the questionnaire is given by thomsen (2005). some information about the cost of waste water treatment installations in antarctica can be extracted from table 1, although most countries did not answer question 9. the results show that the cost varies between $9000 for argentina (with some equipment being a donation from the netherlands) to $2.2m for replacing the nonfunctional treatment system at the australian davis station. for stations serving about 100 people, such as those run by new zealand and south africa, the cost is approximately $240 000 for a system with biological treatment. the running costs vary between $800 (south africa) and $9500 (new zealand) per annum. discussion this study shows that despite the fact that antarctica is the largest pristine wilderness on the planet, and is very sensitive to environmental disturbance, 52% of the 71 stations located there lack any kind of waste water treatment system (table 2). moreover, 37% of the 41 permanent stations with year-round occupancy lack a treatment system (table 2). it is also important to note that most of the stations that have a treatment system installed it during the past decade. for example, the american mcmurdo station, the largest human settlement in antarctica, with more than 1000 people during the summer, installed its sewage remediation plant in 2003, and prior to that had no waste water treatment at all (conlan et al. 2004). the organic enrichment by the sewage water from mcmurdo station has had a significant negative impact on the benthic community structure of mcmurdo sound (conlan et al. 2004). high densities of coliform bacteria were found as far back as 1992 along the 1-km shoreline outside the base, and the plume extended 200–300 m seaward (howington et al. 1992). to inform future waste water management decisions, it is important to know how effective the treatment methods reported in table 3 are in preventing the release of humanderived microbial agents to the antarctic environment. only four stations have tertiary treatment, or use uv sterilization (e.g., the uk) or electric fields and disinfection (e.g., russia), to handle the problem of microbial agents. other treatment methods, such as maceration (used by four stations), do not reduce the likelihood of spreading human-derived microbial agents to the antarctic environment. maceration may, in fact, increase microbial levels if not performed properly. hughes & blenkharn (2003) showed that conditions favouring microbial growth were created in the sewage water tanks of the uk’s rothera station with the addition of warm water from, e.g., showers and macerated food waste from the kitchens. the results from the present study also show that two stations with biological treatment (new zealand and south africa) have problems with treatment during the summer seasons, when there are many visitors to the stations. table 2 the waste water treatment for different types of research stations in antarctica no. of stations sewage treatment (%) permanent stations 41 63 summer stations 26 31 field stations 4 0 all stations 71 48 table 3 type of waste water treatment systems used at permanent and summer stations in antarctica type of treatment permanent stations summer stations primary 1 secondary 4 3 tertiary 1 primary & secondary 1 primary, secondary, tertiary 1 biological plant 8 1 septic tank 2 3 membrane & biological 1 chemical & biological 1 mechanical & uv filter 1 electric field & disinfection 1 maceration 4 sewage treatment plant 1 no treatment 15 18 total number of stations 41 26 survey of waste water disposal practices at antarctic research stationsf. gröndahl et al. polar research 28 2009 298–306 © 2008 the authors 303 australia has had major problems at one of its stations (davis), and several countries (france, norway and russia) do not know if their treatment systems are efficient. the us reported operational problems at mcmurdo station well into the second year of operation of the waste water plant (antarctic treaty secretariat 2006). thus, it is likely that even the stations that have some kind of waste water treatment are not treating their waste water and grey water effectively. when waste water and grey water containing microorganisms are released, microorganisms can remain viable at low-temperature antarctic conditions for prolonged periods (smith et al. 1994; statham & mcmeekin 1994; hughes 2003, 2005). hughes (2005) showed that during the austral summer, in which intensive sunlight in combination with ozone depletion increases harmful uv-b radiation, solar radiation may reduce the number of viable waste water derived microorganisms released to the antarctic environment. however, hughes (2005) also stresses that this effect is not reliable, and that every effort should be made to treat waste water to eliminate human-derived microbial agents. microorganisms may also have the potential to infect and cause disease, or become part of the gut flora of local bird and mammal populations, as well as fish and marine invertebrates (de lisle et al. 1990; olsen et al. 1996; broman et al. 2000; palmgren et al. 2000; hughes 2003; stark et al. 2003; hernandez et al. 2007). human pathogens may also be introduced to antarctica by natural means, such as individual seabirds and fur seals that can wander to lower latitudes near south america, where they could pick up potential pathogens such as e. coli (hernandez et al. 2007). in addition to microorganisms, grey water may also contain residues from personal hygiene products and detergents with surfactants that may be environmentally harmful. george (2002) has shown that biodegradation may occur in antarctic coastal waters of the commonly used anionic surfactant sodium dodecyl sulphate (sds). however, not all detergent products are as readily degradable as sds. the antarctic treaty regulates the treatment of human waste and sewage, but requires sewage treatment by at least maceration only for human populations of more than 30 persons (antarctic treaty secretariat 1998b). even if the output from waste water disposal is sometimes negligible for small operations, it is most probably cumulative in terms of the environmental impact resulting fromslow decomposition rates in the cold environment. during the summer season, a small station such as wasa may use relatively large volumes of water—the average water consumption is 100 litres per person per day. australian stations have reported similar water consumption during the summer, and higher rates (135 litres per person per day) in winter (thomsen 2005). this study shows that nearly 20% of the permanent stations have biological treatment plants (table 3). however, biological treatment with microorganisms may not be appropriate for summer season stations such as the swedish wasa station. to survive, microorganisms (predominantly bacteria) need food in the form of organic material, and that can only be supplied during summertime visits. one of the questions in the survey concerned the length of time taken to start the sewage treatment process. that could not be answered for those countries with permanent stations (table 1). even though most of the countries with summer stations reported that it takes 1–2 days to get the system going, depending upon the type of system used (table 1), it is more likely to take a much longer time. often, the time stated is the time taken under optimal conditions, but start-up can be especially difficult if the winter has been hard and long, and if the treatment plant is located outdoors. if this is the case there is a risk of frozen pipes and tanks, and before these can be used again they need to be thawed. another aspect is that waste water disposal methods have, to a large extent, been developed in temperate areas, but some technologies commonly used elsewhere do not function in the antarctic. to be effective in the antarctic, practices need to be adapted to local conditions, and an installation at the swedish research station wasa, back in 1988/89, proved to be so inefficient that it was removed a few years later. thus, for antarctic conditions, it is important to choose the most suitable sewage treatment methods, and to be aware of problems that may be related to the technology in the harsh environment. the climatic conditions in antarctica, at least in areas such as the antarctic peninsula or the sub-antarctic islands, are no more extreme than conditions in, for example, scandinavia, greenland, alaska and canada, which have large populations and efficient waste water treatment. although the treatment technology may cope with the harsh climate, the experience at stations like mcmurdo is that the process control often does not work as originally designed (antarctic treaty secretariat 2006). these challenges are especially problematic in antarctica because of the lack of nearby technical support that is readily available in most other parts of the world. there are very few published reports on the efficiency of sewage treatment methods in antarctica. bruni et al. (1997) studied the outfall from the sewage disposal plant of the italian base stations in terra nova bay. the results showed that when the station population was high, the plant was unable to cope with the high sewage input level, and did not work satisfactorily. this is in accordance with results from the present study, which showed that survey of waste water disposal practices at antarctic research stations f. gröndahl et al. polar research 28 2009 298–306 © 2008 the authors304 both south africa and new zealand have difficulties in achieving high-quality effluent during periods of a high influx of people to the stations during the summer period. hughes (2004) studied the submerged aerated biological filter sewage treatment plant (hodge separators ltd., penryn, cornwall, uk) installed in 2003 at the permanently occupied british rothera research station, located on adelaide island, antarctic peninsula. the one-year study showed that the treatment plant was efficient in reducing the concentration of faecal coliforms in waste water released from the station (hughes 2004). similar technology to that used at rothera research station has also been installed at both the american mcmurdo station and the new zealand scott base. this study found that new zealand has problems with sewage treatment, at least during the summer season, as have australia, japan and south africa. for three countries (france, russia and norway), the systems were too new for any conclusions to be drawn about functionality. of the 10 countries that reported satisfaction with their treatment system in response to our survey, at least the us has subsequently reported problems at the mcmurdo station (antarctic treaty secretariat 2006). more studies on the efficiency and functionality of waste water treatment systems in antarctica are needed in the future. the use of efficient technology at all permanent antarctic research stations would greatly reduce the human impact on the pristine antarctic environment. to protect the antarctic environment from human-derived microbial agents, waste water and grey water released from the smaller summer stations should also be subjected to treatment. sweden is looking at different treatment systems that can be used at the wasa station. thomsen (2005) has looked at the demands of treatment systems for grey water, and has investigated alternative products on the market. the results shown in table 1 show that the costs for installation and operation of waste water treatment systems in antarctica are reasonable in comparison with the overall cost of antarctic research. conclusions although there is a legal system in place that is designed to protect the antarctic environment, releasing untreated waste water is still in accordance with the legal obligations as long as there are not more than 30 people on the station. this study shows that 37% of the permanent antarctic stations, and 69% of the summer stations, are lacking any form of waste and grey water treatment system. the study also shows that the treatment methods used at many stations are not efficient enough to reduce the release of microorganisms. stations with existing treatment systems have reported operational problems and malfunctions. there is also a need for more environmental monitoring, including monitoring of human-derived microbial agents around the stations. the environmental impact of the waste water released should be analysed and appropriate treatment plants should be installed on a case-by-case basis, as the introduction of treatment plants at all stations may not be possible or even necessary. apparently there is still much to be done by the 28 nations running the more than 80 research stations in antarctica. the technology exists for effective waste water treatment in antarctica. the use of efficient technology at all permanent (and most summer) antarctic research stations would greatly reduce human impact, such as introduced human-derived microbial agents, on the antarctic environment. acknowledgements this study formed part of a master of science thesis by ann thomsen at the department of industrial ecology, royal institute of technology, stockholm. the work was jointly supervised by the swedish polar research secretariat (the swedish antarctic research programme) and the department of industrial ecology at the royal institute of technology. both are greatly acknowledged for excellent working facilities. the first version of the manuscript was much improved by comments from one anonymous reviewer and from kevin a. hughes at the british antarctic survey, cambridge. the language was checked by mary mcafee. all are greatly acknowledged. references antarctic treaty secretariat 1998a. protocol on environmental protection to the antarctic treaty. accessed on the internet at http://www.ats.aq on 28 april 2008. antarctic treaty secretariat 1998b. annex iii to the protocol on environmental protection to the antarctic treaty. waste disposal and waste management. accessed on the internet at http://www.ats.aq on 28 april 2008. antarctic treaty secretariat 2006. wastewater treatment in antarctica: challenges and process improvements. information paper (ip) 60. agenda item cep 12 presented by the united states at the antarctic treaty consultative meeting, edinburgh, uk, 12–16 june 2006. broman t., bergström s., on s.l.w., palmgren h., mccafferty d.j., sellin m. & olsen b. 2000. isolation and characterization of campylobacter jejuni subsp. jejuni from macaroni penguins (eudypte chrysolophus) in the sub-antarctic region. applied and environmental microbiology 66, 449–452. bruni v., maugeri t.l. & monticelli l. 1997. faecal pollution indicators in the terra nova bay (ross sea, antarctica). marine pollution bulletin 34, 908–912. survey of waste water disposal practices at antarctic research stationsf. gröndahl et al. polar research 28 2009 298–306 © 2008 the authors 305 http://www.ats.aq http://www.ats.aq cia (central intelligence agency) 2008. the world factbook. antarctica. accessed on the internet at http://www.cia.gov on 28 april 2008. comnap (council of managers of national antarctic programs) 2005. the national antarctic programs. accessed on the internet at http://www.comnap.aq on 10 december 2005. conlan k.e., stacy l.k., hunter s.l. & john s.o. 2004. benthic changes during 10 years of organic enrichment by mcmurdo station, antarctica. marine pollution bulletin 49, 43–60. de lisle g.w., stanislawek w.l. & moors p.j. 1990. pasterurella multocida infections in rockhopper penguins (eudyptes chrysocome) from campbell island, new zealand. journal of wildlife diseases 26, 283–285. george a.l. 2002. seasonal factors affecting surfactant biodegradation in antarctic coastal waters: comparison of a polluted and pristine site. marine environmental research 53, 403–415. hernandez j., prado v., torres d., waldenström j., haemig p.d. & olsen b. 2007. enteropathogenic escherichia coli (epec) in antarctic fur seals arctocephalus gazella. polar biology 30, 1227–1229. howington j.p., mcfeters g.a., barry j.p. & smith j.j. 1992. distribution of the mcmurdo station sewage plume. marine pollution bulletin 25, 324–327. hughes k.a. 2003. influence of seasonal environmental variables on the distribution of presumptive fecal coliforms around an antarctic research station. applied and environmental microbiology 69, 4884–4891. hughes k.a. 2004. reducing sewage pollution in the antarctic marine environment using a sewage treatment plant. marine pollution bulletin 49, 850–853. hughes k.a. 2005. effect of antarctic solar radiation on sewage bacteria viability. water research 39, 2237–2244. hughes k.a. & blenkharn n. 2003. a simple method to reduce discharge of sewage microorganisms from an antarctic research station. marine pollution bulletin 46, 353–357. iaato (international association of antarctica tour operators) 2008. tourism statistics. accessed on the internet at http://www.iaato.org on 28 april 2008. olsen b., bergström s., mccafferty d.j. sellin m. & wiström j. 1996. salmonella enteritidis in antarctica: zoonosis in man or humanosis in penguins? lancet 348, 1319–1320. palmgren h., mccafferty d., aspan a., broman t., sellin m., wollin r., bergström s. & olsen b. 2000. salmonella in sub-antarctica: low heterogeneity in salmonella serotypes in south georgian seals and birds. epidemiology and infection 125, 257–262. persson p.o. (ed.) 2005. miljöskyddsteknik—teknik och strategier för ett hållbart miljöskydd. (environmental technology—strategies and technical solutions for a sustainable environmental protection.) stockholm: dept. of industrial ecology, royal institute of technology. smith j.j., howington j.p. & mcfeters g.a. 1994. survival, physiological response and recovery of enteric bacteria exposed to a polar marine environment. applied and environmental microbiology 60, 2977–2984. stark j.s., riddle m.j. & simpson r.d. 2003. human impacts in soft-sediment assemblages at casey station, east antarctica: spatial variation, taxonomic resolution and data transformation. austral ecology 28, 287–304. statham j.a. & mcmeekin t.a. 1994. survival of faecal bacteria in antarctic coastal waters. antarctic science 6, 333–358. stenström t.a. 1996. sjukdomsframkallande mikroorganismer i avloppssystem. riskvärdering av traditionella och alternativa avloppslösningar. (pathogenic microorganisms in sewage systems. risk validation of traditional and nontraditional sewage solutions.) report 4683. stockholm: swedish environmental protection agency. thomsen a. 2005. waste water treatment in antarctica—a feasibility study for grey water at wasa station. master of science thesis. dept. of industrial ecology, royal institute of technology, stockholm. survey of waste water disposal practices at antarctic research stations f. gröndahl et al. polar research 28 2009 298–306 © 2008 the authors306 http://www.cia.gov http://www.comnap.aq http://www.iaato.org development of arctic sea-ice organisms under graded snow cover rolf gradinger. michael spindler and detlev henschel gradinger, r . . spindler, m. & henschel, d. 1991: development of arctic sea-ice organisms under graded snow cover. pp. 295-307 in sakshaug, e.. hopkins. c . c. e. & britsland, n . a . (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, 12-16 may 1990. polar research l o ( 1 ) . in may 1988, the short-term response of sea-ice organisms to manipulated changes in snow cover (no snow cover, natural snow cover, natural snow cover + black foil) was investigated in one ice floe located in the east greenland current northwest of svalbard over a period of three weeks. autotrophic organisms (flagellates and diatoms) were concentrated in the lowermost 30cm of the floe. i n the field without snow cover, the highest diatom concentrations were observed. consisting nearly entirely of pennate forms, together with a maximum bacterial abundance. the community of larger protozoa and smaller metazoa was dominated by ciliates. under natural conditions the flora consisted of both flagellates and diatoms, while turbellaria were the dominating animals. in the darkened field. the organism concentrations decreased with time. the results indicate that brine drainage. induced by changes in ice temperature, can reduce concentrations of ice organisms over short time scales. rolf gradinger and michael spindler. alfredwegener-lnrtitut fur polarund meeresforschung, bremer haven, columbusstr., d-2850 bremerhaven, germany. detlev henschel, universitar bremen, institut fur marine botanik, postfach 330440, 0-2800 bremen 33, germany (reuised december 1990). introduction sea ice is a characteristic feature of polar regions. it covers 7-14.106kmz of the arctic ocean (walsh & johnson 1979) and offers a unique habitat for a highly diverse biocoenosis. first reports about diatoms associated with ice roes were given by ehrenberg (1841). nansen (1906) was the first to discuss trophodynamic interactions between ice diatoms, protozoa, crustacea, fish and seals. in arctic sea-ice algal, cells were mostly found concentrated in layers at the bottom of the ice floes or as ice-associated mats dominated by melo sira arcfica (homer 1985). in contrast to results from the antarctic (e.g. ackley et al. 1979), no interior communities were observed in arctic sea ice. a variety of invertebrates has been collected from the bottom layer communities dominated by organisms belonging to the meiofauna size range (carey 1985), but very few quantitative estimates are given. the structure of the cryopelagic food web and its importance for pelagic organisms are therefore not fully understood. in the arctic most investigations have been carried out in coastal shelf areas due to the relatively easy accessibility of these sites. based on the occurrence of gam marid amphipods, carey (1985) described four different regional community types: three fast ice communities over different water depths and one multi-year ice community over deeper water, highlighting the lack of studies in deep water areas. experiments using graded snow cover to simu late different light regimes have been performed both in the arctic (apollonio 1961) and antarctic (grossi & sullivan 1985; palmisano et al. 1985a, b; sullivan et al. 1985; grossi et al. 1987; pal misano et al. 1987) to study the effects of light on the photoadaptation and development of ice algae ' and to follow the response in abundance and diversity of the bacterial assemblages. in the arctic, apollonio (1961) observed a decrease in chlorophyll concentration following the removal of a natural snow cover from ice floes. he con cluded that increased heat absorption by the ice algae and changes in the ice structure as a result of the increased light intensities lead to a release of the algae from the bottom layer. as a second possible mechanisms for the chlorophyll a reduction he proposed physiological inhibition of the algae due to unnaturally high light intensities. on the other hand studies in the antarctic showed an enhanced development of both algae and bac teria in terms of biomass and activity as a result of reduced snow cover. 296 r . gradinger, m . spindler & d . henschel our study was located between greenland and svalbard in the western part of the fram strait. where the major outflow of polar water and multi year ice floes from the arctic basin takes place (tschernia 1980). we followed the development of the ice community in one ice floe during a period of three weeks under three different in situ light regimes in order to test whether reduced snow cover inhibits or promotes growth of ice organisms, and to determine which mechanisms are responsible for the observed differences between the results of apollonio (1961) and ant arctic researchers. material and methods the investigation was carried out during r/v pol arstern expedition ark v/1 in may 1988. the icebreaker was moored to an ice floe (safe island) within the east greenland current and drifted for three weeks in the area between 8072' to 80'52" and o"2o'w to 5"24'e (hoeber et al. 1989). three experimental fields ( n , l, d ) of 10 m z each were set up close to each other in a homogeneous part of safe island and treated in different ways to evaluate the influence of light on the development of the ice organisms. field n (natural) was not manipulated in any way and served as a control, while the snow cover was removed regularly from field l (light). field d (dark) was darkened with a 0.5 mm thick black foil. to avoid heating of the ice by light absorption of the foil, it was covered by a layer of snow. light intensities were evaluated after coring with a spherical 4 n-li-cor quantum radiometer in and below the ice after removal of the ice core. duplicate ice cores (less than 10 cm apart) were taken from each field every 4th day beginning on 5 may until 24 may 1988, using 3' sipre ice augers. sections of ice were cut with a stainless steel saw. the temperature of the ice was measured directly after coring in 5 cm intervals. sections of the first core were melted in the dark at 2°c and analysed within 24 hours for determination of salinity and pigment con centration (chlorophyll a . phaeopigments). the pigment concentrations were measured with a turner fluorometer according to evans & o'reilly (1966). the salinity of the melted cores was measured with a wtw lf 191 con ductometer. the structure of the ice cores was determined from vertical thin sections of the ice core. the second core was cut i n 10 cm long segments which were melted in 3 liters of 0.2 pm filtered seawater to avoid osmotic stress on the ice organ isms during the melting procedure (spindler & dieckmann 1986; garrison & buck 1986). sub samples of 100ml from the three deepest seg ments of the core were fixed with borax-buffered formalin (end-concentration 1% formaldehyde) and filtered on 0.2-vm irgalan-black stained nuclepore filters after staining the organisms with dapi (porter & feig 1980). counts of bacteria, autoand heterotrophic flagellates and diatoms were made with a zeiss epifluorescence micro scope under uv (filter set 487701) or blue light excitation (filter set 487709). ciliates and metazoa were concentrated from the total sample volume using 20 pm mesh and live-counted under a dis secting microscope. one additional core was taken from each field on 24 may to estimate the accuracy of the deter mined organism concentations. the average dis crepancy of the results from one core to the average of both was 19.5% (range: 5.2-33.3%). these values fall i n the range for the statistical error which is expected by individual counts below 100 units per species (helcom 1983). hori zontal patchiness of the ice oganisms in our exper imental area could therefore be neglected for the purposes of this study. results ice structure the ice thickness in the sampling site showed only small variations between 1 6 4 1 7 1 cm, and an average natural snow cover of 27cm was measured. the ice cores consisted entirely of congelation ice; only the upper 10 cm contained snow ice, frazil ice or a mixture of these 3 different ice textures (lange & eicken pers. comm.). light as a result of daily differences of the cloud cover the absolute surface light intensities ranged between 20004500 pe.m-'.s-'. the available light intensities inside and below the ice as per centage of the surface irradiance (fig. 1) showed no time dependency. under natural conditions development of arctic sea-ice organisms 297 ". . 0 ' 03 2 t f y 23 3 water 3,6 4 4,5 5 i i i 1 1 1 1 1 1 0,oo 1 0,o 1 0,l 1 10 100 percent surf ace llgh t lntensl t y sample field d + field l ++ field n fig. 1 . average percentages of surface light in and bclow the ice in fields n , l. and d during the investigation. (field n ) an average of 0.24% (4.4 10.1 we.rn-*.s-') of the surface irradiance reached the bottom of the ice floe. in field l 4.71% (105-150pe.m-f-s-r) and in the dark ened field d only 0.01% (0.3-0.4ye.m-2.s-') was measured at the ice-water interface. the dif ferences in the snow cover were still reflected in the measurements 5 m below the ice. temperature three major fluctuations of the air temperature occurred during the 3-week investigation period (fig. 2). first there was a warming period with the temperature rising from below 18°c to 0°c. the second sampling of ice cores took place at the end of this warming period (9 may). the temperature subsequently dropped to between -6 and -12°c. during this time two samples were taken (13 may and 17 may). toward the end of the investigation temperatures increased to above -6°c. ice samples were taken two times (21 may, 24 may) during this period. the variations of air temperature were reflected in the ice (fig. 3), however, with different mag nitudes in the fields n , l, and d. on 5 may the ice temperature in the upper 80cm was below -7°c. during the first warming period a steep increase was observed. without insulating snow cover (field l), the ice temperature rose to above -5.2"c in the entire core and even above -2°c in the upper 5 cm. the disturbed snow cover in field d resulted in a faster response to variations of the air temperature than in field n , but in a slower response than in the exposed field l: this demonstrates the effect of snow cover on the heat exchange between ice and atmosphere. as a consequence of the subsequent decrease in air temperature (11 may-20 may), the ice tem perature in field l again dropped to below -5"c, but only in the upper 30 cm. the increase in air temperature toward the end of the investigation showed effects in fields l and d: the ice core temperatures in the upper 80 cm had increased from below -7°c to more than -3°c in field l 0 -2 4 -6 8 10 12 18 -20' ' i 5 10 15 20 25 d a t e (mav 1999) 0 ~ i c c c o r i n g fig. 2. fluctuations of the air temperature during the inves tigation (0 = ice coring date). 298 r . gradinger, m . spindler & d . henschel date (may 1988) 5 9 13 1 7 2 1 24 5 9 13 1 7 2 1 24 5 9 13 1 7 2 1 24 fig. 3. fluctuations of the ice temperature ( " c ) during the investigation ( 5 may-24 may 1988) in fields l . n. and d . l, -4°c in field d and -5°c in field n . t h e temperature in the bottom 2 0 c m of the ice remained almost constant in all three fields. salinity changes in salinity (fig. 4) correspond t o the fluctuations in temperature. the largest changes occurring in field l. between 5 may and 13 may salinity dropped from more than 10% t o values below 6%. the same was observed in fields d and l. but with less variation and an increasing time lag between changes in air temperature and salinity. i n these two fields the salinity remained above 7%. in the lowest 2 0 c m of the ice the measured fluctuations were small (2.9-4.9%) and were not related to time or air temperature. the relation of the total salt content in the upper 80 cm of the core to the total salt content of the core (fig. 5 ) demonstrates t h e drainage of salt from the upper half of the ice floe to the lower parts during the first 8 days of the study. during this period t h e ratio decreased from an initial value of 59% in all fields t o 46% and 51% in fields l and d , while remaining more or less constant in field n . this phenomenon, together with the decrease in t h e integrated salt content of the ice. indicates drainage of brine from t h e upper decimetres of t h e floe through t h e ice into the water column during this period. pig men ts a distinct maximum of chlorophyll a was observed in the lowermost locm of all cores collected, but showed large temporal changes (fig. 6). in field l t h e concentration dropped from initially 1.45 m g . m 3 t o values below 0.7 mg 5 9 13 1 7 2 1 24 1 3 0 ~ ~ development of arctic sea-ice organisms 299 date (may 1988) * ‘i * 5 9 13 17 21 24 5 9 13 1 7 2 1 24 t * * t * * ~* fig. 4. fluctuations of the salinity (%) during the investigation (5 may-24 may 1988) in fields l . n , and d. +) y no data field n 8 3 55 0 a g t! 3 50 5.5. 9.5. 13.5. 17.5. 21.5. 24.5. date (may 1988) fig. 5. relation of the salt content (%) in the upper 80 cm to the total salt content of the core during the investigation. chl a.m-3. the same changes were found in fields d and n. a period of increasing chlorophyll a concentrations followed the initial decrease. on 21 may the values exceeded 1.1 mg chl a . m 3 in fields l and d with a maximum of 1.93 mg chl a ~ m ~ in field l. at the end of the study a sharp decrease to values below 0.5 mg chl u . m 3 was observed only in field l, while the concentrations in fields n and d remained above 0.8mg chl a.m-3. the ratio of phaeopigments to chlorophyll a is shown in fig. 7. values below 0.5 were charac teristic for the lower portion of the ice floe in all three fields, while values above 1.5 dominated in the upper decimetres. the decrease of this ratio during the cooler period (11 may-20 may) in upper parts of fields land d was due to increasing chlorophyll a values with a maximum of 0.08 mg 300 r . gradinger, m. spindler & d. henschel date (may 1988) 5 9 13 17 21 24 -30k : e -1 10 -130 -150 -170 i ''i t i 5 9 13 17 21 24 -10 1 7 1 n l * * * t -150 -170 5 9 13 17 2 1 24 -10 '0.05' d 3 0 1 -50 i:::. * * * * -70 1 * * * * -90 1 10 -130 -150 -170 fig. 6. fluctuations of t h e chl a contcnt (rng.m-') during the investigation ( 5 may-24 may 1988) in fields l, n . and d. chl a . m 3 at the top of field l on 13 may i n contrast to concentrations of 0.01 mg chl a . m ' in the same level at the beginning and the end of the investigation. bacteria, autotrophic and heterotrophic flagellates, diatoms bacteria, diatoms, autotrophic and heterotrophic flagellates had their maximum abundance i n the lowest locm of the floe (table 1). this distribution pattern was very distinct for the autotrophic organisms (diatoms, autotrophic flagellates), while bacteria and heterotrophic flagellates were distributed more homogeneously in the lower 30cm of the floe. the development of the sea ice community in the three fields n. l , and d is shown in fig. 8. i n the fields l and d. the cell numbers decreased until 13 may; n o data were available from field n on 9 may due to loss of the samples. under natural light conditions (field n) the abundance of diatoms and autotrophic flagellates increased slowly after 13 may. the generation times for these two groups were estimated using an exponential growth model leading to a doubling time o f t , = 9 . 6 d (n, = no.e"072.', n = cells.ml-l, t = time (d), r2 = 0.59) for diatoms and 19.3 d (n, = no.e".036'', r2 = 0.34) for auto tropic flagellates. the density of heterotrophic organisms (bacteria, heterotrophic flagellates) showed no significant variation during the inves tigation. the enhanced light availability in field l resulted in a strong proliferation of diatoms. highest densities of 15,000 diatoms.ml-i w e r e , 5 9 13 17 21 24 * * * -130 -150 -170 i "' development of arctic sea-ice organisms 301 date (may 1988) 5 9 13 1 7 2 1 24 e31 -10 d -301 * 1 1; * i -170 fig. 7. fluctuations of the ratio of phaeopigments to chl a during the investigation (5 may-24 may 1988) in fields l , n . and d reached on 24 may in the lowest 3 cm of the floe. the increase followed an exponential growth curve (n, = no.e".22", r2 = 0.94) with a gen eration time of 3.2 d. the contribution of centric forms t o the total number was below 1%. the dominating pennate cells belonged to the genus frugilluriopsis. on the last sampling day the chlorophyll autofluorescence was very weak, indi cating a senescence of the diatoms. coinciding with the diatom peak, the bacteria attained their maximum (1.2. lo6 cell-ml-') on the last sam pling day, a large fraction being attached to the diatom cells. in contrast to the diatom population the auto table 1 . average abundances of bacteria (10'.ml-'), diatoms (cells.ml-'). autotrophic and hctcrotrophic flagellates icells. m l ' ) in the lowermost decimetres of the studied ice floe under natural light conditions (field n ) during the whole investigation period. autotrophic heterotrophic depth bacteria flagellates diatoms flagellates (cm) ( 1 0 ' . m l ' ) (cells .mli) (cells. m l ' ) (cells. mli) 140-150 364 2 226 304 2 56 162 t 69 39 2 21 150-i60 223 2 46 533 2 120 211 5 12y 216 2 315 160-170 344 t 51 1416 z 361 102r z 395 321 -f 385 302 r . gradinger. m . spindler & d . henschel abundance (1000/ml) 4 3 2 1 0 n . . . . a i 5 9 1 3 17 21 2 4 5 9 13 17 21 2 4 5 9 13 17 21 2 4 date (may 1988) bacterla ( ' 1 0 e 3 ) autotr. flag. dlatoms heterotr. flag. fig. 8. fluctuations of the average ahundances ( i o o o ~ m l ' ) of bacteria. autorrophic and heterotrophic flagellates. and diatoms in the lowermost 20cm of the ice in fields n . l . and d. trophic and heterotrophic flagellates did not show a constant increase with time. the lowest concentrations of all organism groups were observed in t h e darkened exper imental field d. a decrease of the cell densities occurred during the first 8 days and after 17 may. the chlorophyll a autofluorescence of the diatoms was very intense at the end of the study. indicating a high chlorophyll a content per cell. ciliates and m e t a z o a a rich and highly diverse community of ciliates and small metazoa (fig. 9. table 2) lived inside t h e ice, with more than 95% of all organisms found in the lowest 2 0 c m of the floe. under natural light conditions (field n ) the community was dominated by ciliata (29% of all organisms) and acoelic turbellaria (51%). during table 2 . aleragc abundances (organisms.m-') of ciliates and meiazoa in the three ice fields during the entirc investigation period: cil. = ciliara: nem. = nematoda: turb. = turhellaria: rotat. = rotatoria: naup. = copepoda: nauplii: copep. = copepodites: harpact. = harpacticoids. field cil nem turb rotat naup copcp harpact sum l ?03(hi 500 43so sou 3w 5 0 1 5 0 26.150 ri 8hxr 1450 15140 200 3w 50 250 29.600 d 4300 2 5 0 y2s0 50 loo0 0 1 so is imjo ( 7 w r ) ( 2 % ) ( 1 7 v ) (25) ( 1 % ) ( < i c e ) ( < i % ) ( 2 9 4 ) ( 5 3 ) ( 5 1 % ) ( i l ' ? ) ( 1 3 3 ) ( < i % ) ( < i % ) ( 2 9 5 ) ( 2 % ) (62%) ( < i % ) ( 7 % ) (0% ) (1%) development of arctic sea-ice organisms 303 enhanced light intensities (field l). it was dom inated by ciliata (78%), especially of the genus didinium. in contrast t o field n, nauplii (1%) were nearly absent, while the number of tur bellaria (17%) remained constant after an initial decrease. the darkened field d had a similar community to field n, but concentrations were lower. ciliata (29%) and turbellaria (62%) were the numerically dominating organism groups, exhibiting large fluctuations during the period of investigation. 160 , . f l e l d l 140 120 loo 80 60 40 20 0 1 100 80 > 60 v al v u c 3 d 40 m 20 0 100 80 i : i l i a t a 60 40 20 0 5 9 13 17 21 24 d a t e (may 1988) fig. 9. fluctuations of the average abundances (1. -') of ciliates and metazoa in the lowermost 20 cm of the ice in fields n, l , and d. the first 4 days, the concentrations of these groups increased and remained afterwards more or less constant. nauplii (13%), copepodites (<1%), adult harpacticoids (<1%), rotatoria (<1%) and the nematode theristus melnikoui, tschesu nov 1986 (5%) were regularly found in lower densities. a different community developed under discussion the occurrence of biomass maxima in the lower decimetres of ice floes is well known both from the antarctic and the arctic (see horner 1985 for review). most of the arctic studies focused on the lowermost 2-20cm of the ice, coloured by ice algae (apollonio 1961; kern & carey 1983; legendre et al. 1987; smith et al. 1987; smith et al. 1989a), while results from measurements throughout the whole ice cores in distinct strata are only available from antarctic sites (garrison et al. 1986), with the exception of the study from hsiao (1980) in the canadian arctic. our data clearly show that the highest con centrations of a viable ice flora and fauna occur in the bottom part of the ice floe. estimates of the algal standing crop (mg chl a . m-*) from various arctic regions (table 3) show that the algal de velopment in early spring starts in the middle of april and lasts until the beginning of may (horner & schrader 1982; smith et al. 1989a). the abso lute values are mostly an order of magnitude higher than those observed in our study. the neritic location of the other areas studied could be indicative of higher initial populations of algae inside the fast ice in connection with increased nutrient supply, e.g. by tidal mixing during the growth season (cota et al. 1987). moreover, our study area was the most northern one, and there fore the growth season had probably started later than in the other regions, and the biomass maxi mum was not reached. the slight increase in chlorophyll a con centrations in the upper decimetre of ice fields l and d between 9 may and 17 may to values exceeding 0.08 mg-m-3 and the resulting decrease in the ratio of phaeopigments to chloro phyll a are the first clear indications of growing surface ice communities reported from the arctic 304 r . gradinger, m . spindler & d . henschel ruble 3 . chlorophyll a content ( m g . m ~ :) of arctic sea ice from different areas: ( p ) = pack ice. ( f ) fast ice author ice thickness region (cm) time chlorophyll a clashy et al. (1973) mcroy & goering (1974) grainger (1979) chukchi sea bering sca frobishcr bay booth (1984) horner & schrader (1982) smith et al. (1989a) gosselin e t al. (1986) this study davis strait bcaufort sea barrow strait hudson bay fram strait 1.55-170 ( f ) 2 w 3 0 0 ( p ) 200 ( f ) 1 w i m 1 ( p ) > 170-190 ( 0 75-215 ( f ) wlho ( f ) 164-171 ( p ) may-june january march april-may april may (early) may (late) april may april may may may 3.0-30.5 0 . s 3 . 0 0.4 1.6 4.6 o.cl9.6 0.0-2.4 1 4 . k 2 h . s 1.2-8.3 <10.0 100.0 0.1-22.9 1.1-39.7 0.1-0.4 pack ice. only booth (1984) has given a description of brownish coloured ice surfaces, but he proposed that algal cells of pelagic origin were entrapped i n the ice surface by the flushing of the ice with seawater and subsequent freezing. in fast ice of the canadian arctic, hsiao (1980) found high densities of algae on the ice surface; these had developed from trace amounts of chlorophyll a after the ice had formed in late winter. he measured a maximum of 2.27 mg chl a . m 3 at the end of may. during the short period of our study the biomass increase was restricted to the relatively warm period in the middle of the investigation period. sea ice temperature largely influences the habitat of sea ice organisms by controlling the salinity inside the brine pockets and channels. using the equations of assur (1958) for the calculation of the salinity within the brine channels and pockets from the ice temperature data, a strong decrease from values above 120% to those below 1007c~ (field d ) and 70% (field l) occurred between the first t w o sampling dates. studies of the influence of salinity on the activity of ice algae have shown that high salinities above 90-100700 inhibit the growth and physiology of ice algae (kottmeier & sullivan 1988; bartsch 1989). on the other hand the results of bartsch (1989) showed the capability of ice algae to survive extended periods of high salinities and to regain growth when transferred to lower salinities. i t can thus be assumed that the development of ice algae in the upper decimetres of the arctic sea ice was controlled by ice temperature and brine salinity during periods of our experiment. in contrast to the large fluctuations of the tem perature at the top of the ice floe, the conditions at the bottom were rather constant. only minor fluctuations were observed, ranging from 1.8"c to -3°c. the resulting calculated brine salinities of 32-52%0 are not expected to inhibit algal growth (kottmeier & sullivan 1988; bartsch 1989). the sharp drop of chlorophyll a and organism con centrations observed in the fields l, d , and n during the first week corresponds with the obser vations made by apollonio (1961). he found a decrease of algal standing crop from 89.6 to 16.6 mg chl a . m-' (averages) within 7 days during june under very similar ice and snow conditions. this phenomenon was interpreted as a reaction of the ice algae to increased light levels as well as to changes in the physical structure of the ice. he concluded that physiological inhibition is the main cause of pigment loss in sea ice. smith et al. (1989a) monitored the chlorophyll a changes in the lowest h c m of annual ice floes in barrow strait from april to may. their fig. 1a depicts a distinct decrease of the chlorophyll a con centrations between the end of april and the middle of may, first in ice without snow cover and later in ice areas with thicker snow cover. in ice without snow, the algal biomass dropped from 40 mg chl a . m-? to values below 20 mg chl a . m-'. while values remained more or less near this level or even increased in areas with thicker snow cover (2-12cm). smith et al. (1989a) concluded that self-shading was the major mechanism which initi ated the decrease in chlorophyll u in the ice with out snow cover. however, they did not explain development of arctic sea-ice organisms 305 9.3 pe.m-’.s-’ would be sufficient to initiate the spring development of ice algae. cota (1985) observed a 65% higher increase of chlorophyll a in sea ice with moderate to heavy snow cover than under little or no snow cover. similar results were reported by smith et al. (1989a). on the other hand long term experiments using graded snow cover in mcmurdo sound, antarctica revealed highest algal accumulation under snow cleared areas with light intensities over 100 pe.m-’.s-l (grossi et al. 1987). despite the major differences in the study areas (arctic/antarctic) the sampling intervals also differed between these studies. grossiet al. (1987) tooksamplesevery2-3 weeks, while smith et al. (1989a) sampled on a weekly and apollonio (1961) on a daily base. thus the data from the antarctic describe long term changes due to e.g. algal growth and not short time events such as brine drainage processes. the differences between the observed reactions of antarctic and arctic ice organisms reflect, there fore, not only the different biological regimes but also differences in the methodology of the investigations. the estimates of the ice aglal generation times given by grossi et al. (1987) based on the chloro phyll a accumulation are with t, = 2.4d in the field without snow cover and t, = 9.9 d with 25 cm snow cover almost identical to our results, based on the cell counts of diatoms. the difference in the growth estimates of the autotrophic flagellates in comparison to the diatoms can result from various factors. the higher motility of the flag ellates could lead to increased exchange with the water column populations. also selective grazing of herbivores in the ice or a better adaptation of the diatoms to the conditions inside the ice are possible explanations. the chlorophyll a decrease in field l at the end of the investigation corresponded to low chloro phyll a autofluorescence of the diatom cells as seen in the epifluorescence microscope. at the same time the absolute number of diatoms reached a maximum with more than double as many cells compared to previous times and other light regimes. thus, the chlorophyll a decrease was not a result of biomass reduction but of changes in the physiological state of the diatom population, probably as a result of high light intensities or of nutrient depletion. the highest densities of bacteria were also observed during that period. smith et al. (1989b) found that bac teria grow actively in the bottom layer of arctic the existence of an even higher biomass under lower light intensities. taking into account our results on the temporal fluctuations of the total salt content of the ice, we propose a new mechanism which leads to short time changes of organic biomass: the decrease in the chlorophyll a concentrations corresponds to the outflow of brine from the upper decimetres of the floe into the water column. gravity drain age by flushing appears to be the dominant and most effective mechanism for removing salt from sea ice in early spring and summer when the surface temperatures increase (weeks & ackley 1982). martin (1974) and eide & martin (1975) demonstrated that brine drainage processes are connected with oscillating sea water inflow into the ice as a result of convective instabilities, taking place in time scales of seconds to minutes. eide & martin (1975) proposed this mechanism as a pumping source of oxygen and nutrients into the ice. the results of our study indicate that brine drainage as a result of temperature changes in the ice can lead to a release of both algae and animals from the ice into the water. from this point of view the findings of apollonio (1961) and smith et al. (1989a) could be explained in the same way. their measurements were derived in june and at the end of april, when similar meterological conditions as in our study area could be expected. further field studies and experiments have to be undertaken to confirm o u r hypothesis of organism release by brine drainage. we would like to stress the importance of measuring abiotic and biotic parameters over the total thickness of the sea ice since changes in upper parts may strongly influence species abundance and distribution in lower parts. following the initial chlorophyll a decrease, the algal biomass in all three fields increased at different rates. the diatoms, as the dominant autotrophic group, showed highest growth rates (t, = 3.9 d) in field l under light intensities over 100pe.m-2.s-1, while no growth in terms of cell numbers could be observed i n field d (0.3 0.4 pe.m-’.s-l). under natural light intensities (4-10 pe.m-*.s-’) intermediate growth rates were found for diatoms (t, = 9.6 d) and auto trophic flagellates (19.3 d). the discussion in the literature on the effects of light on algal growth is extensive and enigmatic. booth (1984) found light inhibition of in situ primary productivity at intensities >20 p e . m z . s l . according to hor ner & schrader (1982) light intensities of 2.3 306 r . gradinger, m . spindler & d . henschel table 4 . relative abundances of ciliates and metazoa in sea ice from different arctic areas: cil. = ciliata: nem. = nematoda: turb. = turbellaria; rotat. = rotatorla: naup. = copepoda: nauplii: others include harpacticoids. copepodes. polychaetes. amphipods. author region cil. ncm. turb. rotat. naup. others 41% cross (1982) cross & montagna 2 3 4 kern & carey (1983) beaufort sed 47c: 16% 31 % grainger et al (1985) frobisher ba\ < i % 51°c 1 7 r 45% 2 70 pond inlet 59 or stefanson s 7 7 t (1982) this study field l fram strait 780, 2c; 17% 2 7r i 7r < l % field n 290, i 9 51% < i 6 13% l'i: field d 29cr 1 c c 62 c/r < 1 nr 7 7r < 1 010 sea ice, in spite of the fact that algal populations are static or declining. the standing stock of metazoa which was found in the pack ice clearly differed from o t h e r obser vations. t h e studies of cross & montagna (1982). kern & carey (1983) and grainger et al. (1985) from the european sector of the arctic were made in shallow areas with water depths below 5 0 m . making interactions between benthic and sym pagic communities probable. grainger et al. (1985) stated that the major groups inhabiting sea ice are representatives of meroplanktonic and not of holobenthic or pelagic groups. sea ice fauna therefore seemed t o be totally distinct from the dominant arctic zooplankton. t h e dominance of organisms belonging to the meiofauna is well documented (carey 1985). a direct comparison of o u r results with those from other investigations (table 4) is restricted d u e to considerable dif ferences in the methods used. cross & montagna (1982), kern & carey (1983), and grainger e t al. (1985) melted the ice cores directly, which led to an underestimation of fragile organisms such as protozoa (garrison & buck 1986). t h e occur rence of ciliates was only reported by grainger et al. (1985). but in concentrations of 1 to 2 orders of magnitude lower than in o u r study (<1000cells.m-'). another major problem arises from the different mesh sizes used in the different investigations; smaller protozoa may be underestimated in those studies with 63-76 pm mesh size applied. in neritic regions nematodes and nauplii were dominating, while turbellaria and ciliates were numerically most important in the fram strait. these differences may result from the different methology used, especially for the ciliates. o t h e r differences may result from adaptation of life strategies to the annual vs. multi-year ice cover. organisms living i n annual fast ice must at least live partly in the water column or in the benthos, while organisms living inside multi-year ice floes are not released, for a t least a year, into the water column by melting processes. they must therefore be capable of completing their life cycle within the ice. grainger & hsiao (1990) gave the first accounts o n trophic links between the ice organisms by analysing gut contents, but further studies are needed to under stand the dynamics of the ice populations and their relation t o their habitat o n different spatial and temporal scales. acknowledgernenrs. this research was partially supported by the deutsche forschungsgemeinschaft (le 232/15). data on the sea ice texture were provided by m. lange and h. eicken. we thank k. beyer and r. steinmetz for their assistance in the field and in the laboratory. f. riemann for the identification of the nematodes. and g . dieckmann, e . rachor and three ref erees for helpful comments on the manuscript. we are indebted to the crew of r / v polarstern for their extensive assistance. this is awi contribution nr. 395. references ackley. s . f . buck. k . r. & taguchi, s. 1979: standing crop of algae in the sea ice of the weddell sea region. deep-sea res. 26a. 269-281. apollonio. s 1961. the chlorophyll content of arctic sea ice. arcric 1 4 . 197-200. assur. a 1958: composition of sea ice and its tensile strength. >vat. res. council pub!. 598. 106-138. bartsch. a 1989. die eisalgenflora des weddellmeeres (antarktis): artenzusammensetzung und biomasse sowie okophysiologie ausgewihlter arten. ber. pohrf, 63. 1 1 10. booth. j . a . 1984: the eponitc algal community of the ice edge zone and its significance to the davis strait ecosystem. arcric 37. 231243. carey. a g . i r . 1985: marine ice fauna: arctic. pp. 17.v190 in horner. r . a . ( e d . ) : sea ice biota. crc press, boca raton. florida development of arctic sea-ice o r g a n i s m 307 kern, j . c. & carey, a. g . jr. 1983: the faunal assemblages inhabiting seasonal sea ice in the nearshore arctic ocean with emphasis on copepods. mar. ecol. progr. ser. 10. 15f167. kottmeier, s . t. & sullivan, c . w. 1988: sea ice microbial communities (simco) 9. effects of temperature and salinity ‘on rates of metabolism and growth of autotrophs and het erotrophs. polar biol. 8. 293-304. legendre. l., demers. s. & gosselin, m. 1987: chlorophyll and photosynthetic efficiency of size-fractionated sea-ice mic roalgae (hudson bay, canadian arctic). mar. ecol. progr. ser. 40, 199203. martin, s. 1974: ice stalactites: comparison of a laminar flow theory with experiment. 1. fluid mech. 63, 51-79. mcroy, c. p. & goering, j. j. 1974: the influence of ice on the primary productivity of the bering sea. l m t . mar. sci. (alaska) occas. publ. 2 . 403-421. nansen, f. 1906: protozoa on the ice-floes of the north polar sea. pp. 1-22 in nansen, f. (ed.): the norwegian north polar expedition 1893-1896, scientific results 5 (16). j. dybwad. christiania. palmisano, a. c.. kottmeier, s. t., mae, r. l. & sullivan, c. w. 1985a: sea ice microbial communities. 1v. the effect of light perturbation on microalgae at the ice-seawater interface in mcmurdo sound, antarctica. mar. ecol. progr. ser. 21. 37-45. palmisano, a . c., soohoo. j . b. & sullivan. c. w. 1985b: photosynthesis-irradiance relationships in sea ice microalgae from mcmurdo sound, antarctica. j . phycol. 21, 341-346. palmisano, a . c., soohoo, j . b., mae, r. l. & sullivan. c. w. 1987: sea ice microbial communities. vii. changes in under-ice spectral irradiance during the development of ant arctic sea ice microalgal communities. mar. ecol. progr. ser. 35, 165-173. porter, k. g. & feig, y. s. 1980: the use of dapl for iden tifying and counting aquatic microflora. limnol. oceanogr. 25. 943-948. spindler, m. & dieckmann, g. 1986: distribution and abun dance of the planktonic foraminifer neogloboquadrinapachy derma in sea icc of the weddell sea (antarctica). polar biol. 5 . 185-191. smith, r . e. h . , clement. p., cota, g . f. & li. k. w. 1987: intracellular photosynthate allocation and the control of arctic marine ice algal production. j . phycol. 23. 124-132. smith, r . e. h . . clement. p. & head. e . 1989a: biosynthesis and photosynthate allocation patterns of arctic ice algae. limnol. oceanogr. 3 4 , 591-605. smith, r . e . h.. clement. p. & cota. g . f. 3989b: population dynamics of bacteria in arctic sea ice. microb. ecol. 17. 63 76. sullivan, c. w., palmisano. a . c.. kottmeier. s . . grossi. s. m. & moe, r. 1985: the influence of light on growth and development of sea-ice microbial community of mcmurdo sound. pp. 78-83 in siegried, w. r . , candy, p. r . & laws, r . m. (eds.): antarcricnutrientcycles andfood webs. springer verlag., berlin. tschernia, p. 1980: descriprive regional oceanography. per gamon press, oxford. 253 pp. walsh, j . e. & johnson. c. m. 1979: an analysis of arctic sea ice fluctuations, 1953-1977. j . phys. oceanogr. 9, 580-590. weeks, w. f. & ackley, s. f. 1982: the growth, slructure, and properties of sea ice. crrel monograph 82-1. new hampshire. 130 pp. clasby. r. c.. horner. r . & alexander, v. 1973: an in situ mcthod for measuring primary productivity of arctic sea ice algae. j. fish. res. board can. 30. 835-838. cota. g . f. 1985: photoadaptation of high arctic ice algae. nature 315, 219-222. cota, g. f., prisenberg, s. j . . bennett, e. b.. loder, j . w.. lewis, m. r . , anning. j. l., watson, n. h. f. & harris, l. r . 1987: nutrient fluxes during extended blooms in arctic ice algae. j . geophys. res. 92, 1951-1962. cross, a . g. 1982: under-ice biota at the pond inlet ice edge and in adjacent fast ice areas during spring. arcric35. 13-27. cross, a. g . & montagna, p. a . 1982: arctic sea ice faunal assemblage: first approach to description and source of the underice meiofauna. mar. ecol. progr. ser. 8 . 1-8. ehrenberg, c. g. 1841: ein nachtrag zu den vortragen iiber verbreitung und einfluo des mikroskopischen lebens in sud und nordamerika. monafsber. drsch. akad. wiss. berlin. eide, l. & martin, s. 1975: the formation of brine drainage features in young sea ice. j . glaciol. 14. 137-154. evans, c. a. & o’reilly, j . e. 1966: a handbook for the mcasurement of chlorophyll a in netplankton and nanno plankton. narional oceanic and armospheric administration. high1andsln.i. ~ 1 4 4 . garrison, d . l. & buck, k. r . 1986: organism losses during ice melting: a serious bias in sea ice community studies. polar biol. 6. 237-239. garrison, d . l., sullivan, c. w. & ackley, s. f. 1986: sea ice microbial communities in antarctica. biosci. 36. 243-250. gosselin, m., legendre, l.. therriault. j.-c., demers. s. & rochet, m. 1986: physical control of the horizontal patchiness of sea-ice microalgae. mar. ecol. progr. ser. 29, 289-298. grainger, e . h. 1979: primary production in frobisher bay. arctic canada. pp. 2 8 5 2 9 9 in dunbar. m . j. (ed.): primary production mechanisms. cambridge. grainger, e. h., mohammed, a . a. & lovrity. j. e. 1985: the sea ice fauna of frobisher bay, arctic canada. arcric 38. 23-30. grainger, e. h. & hsiao. s. i . c. 1990: trophic relationships of the sea ice meiofauna in frobisher bay, arctic canada. polar biol. 10. 28s292. grossi, s . m. & sullivan, c. w. 1985: sea ice microbial com munities. v. the zonation of diatoms in an antarctic fast ice community. 1. phycol. 21. 401-409. grossi, s . m.. kottmeier, s. t . . mae. r. l.. taylor, g. t . & sullivan, c . w. 1987: sea ice microbial communities. vi. growth and primary production in bottom ice under graded snow cover. mar. ecol. prog. ser. 35. 15f164. helcom (1983): guidelines for rhe balric monitoring pro gramme for rhe second srage. baltic marine environm. prot. comm.. helsinki. 249 pp. hoeber, h.. becker, b. d., goldbach, o., kapp. r. & stah mann, m. 1989: argos-bojen. ber. polarf. 59, 27-29. horner. r . a . (ed.) 1985: sea ice biota. crc press, boca raton, florida. 215 pp. horner, r. & schrader. g . c. 1982: relative contributions of ice algae. phytoplankton, and benthic microalgae t o primary production in nearshore regions of the beaufort sea. arctic 35, 485503. hsiao. s. i . c. 1980: quantitative composition, distribution. community structure and standing stock of sea ice microalgae in the canadian arctic. arcric 33. 768-793. 1841, 202-207. por_007.fm 76 polar research 26 (2007) 76 – 85 © 2007 the authors blackwell publishing incmalden, usaporpolar research0800-03952007 blackwell publishing ltd? 20072617685original articles wellman’s 1906 polar expedition on filmj.a. diesen & n. fulton h i s to r i c a l / b i o g r a p h i c a l e s s ay wellman’s 1906 polar expedition: the subject of numerous newspaper stories and one obscure film jan anders diesen & neil fulton faculty of television production and film studies, lillehammer university college, lillehammer, norway the following contribution, by film researchers jan anders diesen and neil fulton, is the second piece about walter wellman in this issue. whereas capelotti et al. (this issue) focus on technical aspects of wellman’s aborted bid for the north pole in 1906, diesen and fulton look at the media hype surrounding the event. they also describe an obscure short film that includes scenes of wellman in svalbard in 1906. although wellman’s credentials as a polar explorer can be questioned, there is no doubt that he excelled at publicizing his ambitious schemes to the world. —the editor keywords film history; polar expedition; travelogue; wellman; svalbard. preparing a lecture on british travelogues from norway, to be given at the british silent cinema festival in nottingham in march 2006, we were looking for films made by british film-makers in norway in the early years of the last century. one that turned up in the records of the british film institute included bergen harbour in its description. when we received a copy of the film from the national film and television archive its full title was revealed as 1906 the wellman polar expedition—set out from bergen to spitzbergen (charles urban, 470 ft) . it was obvious that this was no ordinary travelogue from norway. the scenes in the film were so much more than the 100-year-old footage of bergen harbour that we’d hoped for. we saw scenes from the norwegian coast, tourist outings and hunting expeditions, and a lot of footage from spitsbergen, showing a range of activities. the film was set apart from others we had seen from the hands of people like robert paul or cecil hepworth. this film was clearly worth a study all of its own. this article aims to unravel the mystery of this film and throw some light on its subject matter. in the summer of 1906, two national events dominated the front pages of the norwegian newspapers, namely the coronation of king haakon and queen maud in trondheim and the passing away of henrik ibsen. it seems that wellman’s polar expedition from spitsbergen was a close contender for third place. these days, the american would-be polar explorer walter wellman is quite understandably a forgotten figure. his five attempts to reach the north pole can only be described as disastrous, and there are only a few lines devoted to him in drivenes & jølle’s (2004) recently published comprehensive history of norwegian polar exploration. ill prepared, wellman attempted several methods of reaching the north pole: by foot (1894), by dogsled (1898–99) and with airships and motorized sledges (1906–09). it was the first airship attempt that was the big media event in 1906, and not only in norway. the polar expedition was a media event long before wellman left for the northern reaches with his airship. his plans were first announced in the american newspapers; european publications weren’t far behind. in norway, wellman was already front page material when he moved north to establish his base on danskøya (danes island) in svalbard. articles in the norwegian newspapers based in the towns closest to wellman’s activities make it possible to follow his route out from bergen [ bergens tidende ( the bergen times )], along the northern norwegian coast [ tromsøposten ( the tromsø post ) and nordkapp ] and further north to spitsbergen. short announcements in bergens tidende described wellman’s progress from his arrival in norwegian waters at arendal (on 19 june 1906) to his arrivals in trondheim (26 june) and tromsø (30 june) (fig. 1). on 6 july, the expedition left tromsø and wellman was “determined to make an attempt as soon as this autumn, even if he were forced to wait until december for favourable winds” (this and text from other newspaper articles has been translated by the authors). on 20 july, the front page of bergens tidende featured an article entitled “who is walter correspondence jan anders diesen, faculty of television production and film studies, lillehammer university college, no-2626 lillehammer, norway. email: jan-anders.diesen@hil.no doi:10.1111/j.1751-8369.2007.00007.x j.a. diesen & n. fulton wellman’s 1906 polar expedition on film polar research 26 (2007) 76 – 85 © 2007 the authors 77 wellman?” the newspaper had found it warranted to print a more rounded presentation of the man: of the new leader of the journey to the north pole, walter wellman, andrée’s successor, we know little more than that he is a correspondent for the chicago newspaper, the record–herald . a few personal notes on this enterprising journalist should therefore be of some interest to the reader. wellman was born 47 years ago in the deep forests of michigan. at the age of 12, he was an assistant at a trading post, where the majority of the customers were north american indians. a year later, he became a printer’s apprentice and founded his own newspaper at the age of 14. after moving to ohio he established several more newspapers, which he subsequently sold. since 1884 he has been the record– herald ’s correspondent and as such commands a princely wage. on assignment from the newspaper, he searched for and was successful in locating the exact spot at which columbus set foot in the new world. ( bergens tidende 20 july 1906) as it was a relatively large newspaper, bergens tidende received telegrams from major bureaus like reuters, and on 18 july it announced that wellman, hopes to establish a wireless telegraph connection with hammerfest within the next 10 days. this dispatch was sent by express steamer from adventfjorden [advent bay, svalbard] and thence with a german tourist ship to digermulen. ( bergens tidende 18 july 1906) it was important to wellman to broadcast news of the expedition swiftly, and the expedition built its own telegraph station in hammerfest in order to be able to transmit dispatches directly from the north pole via danskøya to hammerfest, and thence to the rest of the world. in nordkap we are able to follow the problems encountered during the building of the telegraph station (15 june) and disagreements about the cost of the upkeep of the station (31 august). wellman’s telegraph system was a complex affair: to facilitate the sending of dispatches to the outside world, wellman had three independent wireless stations constructed. station no. 1 was built at hammerfest in norway and connected there to the station at tromsø and its connection with the atlantic cable. station no. 2 was inside the chicago record–herald house (also known as the wellman house . . .), six hundred miles north of hammerfest. station no. 3 was on board the dirigible itself; its wireless, the journalist figure 1 sketchmaps of scandinavia, svalbard and danskøya. svalbard north pole oslo. bergen. arendal. trondheim greenland norway sweden finland . tromsø hammerfest. nordkapp 0° 40° 80° 80° 70° 40° 60° . arctic circle danskøya kongsfjorden spitsbergen 10° 20° 78° 80° svalbard nordaustlandet sassen fjorden danskøya amsterdamøya virgohamna . 78 polar research 26 (2007) 76 – 85 © 2007 the authors wellman’s 1906 polar expedition on film j.a. diesen & n. fulton envisioned, would broadcast the news from nearly seven hundred miles north of his base camp that the airship had reached the pole. should he reach the pole, wellman was taking no chances that his story would be scooped. (capelotti 1999: 68) in a dispatch published a few days later we see that wellman’s telegraph system worked. bergens tidende started their short article in the following way: “the wellman expedition. london. from danskøya on the 20th of this month, in a wireless telegram to the reuters office via hammerfest . . .” ( bergens tidende 23 july). in his book, capelotti illustrates this with a facsimile of a cutting from the chicago record–herald from 24 july 1906, featuring a telegram to president roosevelt from hammerfest dated 21 july. it read: “roosevelt, washington. greetings, best wishes by first wireless message ever sent from arctic regions. wellman” (capelotti 1999: 71). at the turn of the month between june and july, while wellman was staying in tromsø before heading north towards spitsbergen, tromsøposten ran two lengthy articles as well as a number of smaller announcements about him. the first long article (23 june) was reprinted from aftenposten , the national newspaper, and was a report from paris on wellman’s presentation of his dirigible at the workshops of louis godard, the pioneering french balloonist. the author, carl muusmann, describes wellman as a “stanley-type with a mighty moustache over the slightly brutal mouth and a clean-shaven chin. he wears a jacket and a sailor’s cap, making him look very much like a sea captain”. the article, which describes the airship america ’s dimensions and properties, is rounded off with a few financial questions posed to wellman: —and how much will the expedition cost? —at least 1,250,000 francs. after receiving this intelligence one stares once again in awe at all the strange equipment until it is time to bid wellman farewell and bon voyage. —and you believe you will reach the goal? —i hope so, replies the american dryly. if we don’t succeed this time, we will try again. this is how you may allow yourself to talk when you have millions at your disposal. (muusmann 1906, in tromsøposten 23 june) the next article, a week later (30 june), describes the ship and reports on wellman’s plans and assumptions. the expedition attracted tourists and other interested parties to spitsbergen. for example, the journalist otto von gottberg, from the german newspaper berlin lokal anzeiger , established his own camp at virgohamna to follow the efforts of his american colleague—most likely in order to prove that the whole thing was a publicity stunt for the chicago record–herald . (several norwegian newspapers quoted the berlin newspaper.) the norwegian photographer anders beer wilse was also there, as one of the passengers aboard the neptun , a tourist ship. from 18 to 20 august 1906 he took a whole series of photographs of the construction work at wellman’s camp. this series includes the unfinished balloon shed, building material, the car, a sledge, the motor and propeller of the airship, the monument to andrée and the frithjof , the norwegian ship that wellman used that summer. wilse returned to danskøya in 1907 and again in 1909 to document more of wellman’s progress. all of these photographs are found on the website of the national library of norway (http:// www.nb.no/gallerinor/fotografer/ab_wilse.php). fridtjof nansen, the world-renowned polar explorer, scientist and humanitarian, was critical of wellman. nansen visited spitsbergen in 1912 and landed at virgohamna. he reflected that: it was here, then, that the american wellman spent several years inflating his expedition and his airship. a perfectly strange undertaking of its kind. to all experts in the field it was clear from the very start that his plans for the north pole were exceptionally useless; but all the same, it received full backing from an american newspaper, which undertook to bear all the costs, and these were considerable. wellman had seen what sort of sensation andrée’s unfortunate airship journey had aroused; this could be utilized on a grander scale. in the course of several years (from 1906 to 1909), the newspapers of the world were thus filled with constant dispatches about every step of this strange expedition’s preparations, about all the glorious feats it was to accomplish and about all the most modern inventions that were to be used. (nansen 1920: 141; this and other quotations from nansen’s book have been translated by the authors) nansen’s description of wellman’s ineptitude clearly showed his distaste for such hyped-up expeditions led by men merely seeking honour and fame. the descriptions of wellman’s four attempts to reach the pole are sarcastic reading; he portrays an explorer who had no business being in the arctic. he writes of the tourist ships that “each summer brought hundreds of tourists to spitsbergen, where wellman was the star attraction” (nansen 1920: 142). he was critical of wellman’s use of the world’s newspapers. in the aftermath of each failed attempt, wrote nansen, wellman travelled “back to europe to tell of his great achievements and to build a new airship” (nansen 1920: 143). nansen was of the opinion that a polar expedition should be a combination of science, adventure and the peak of physical exertion. a polar expedition was no show. “the greatest show in the arctic” was exactly what wellman’s expeditions were— this is also the title of one of the chapters in capelotti’s book. nansen characterizes wellman as follows: http:// j.a. diesen & n. fulton wellman’s 1906 polar expedition on film polar research 26 (2007) 76 – 85 © 2007 the authors 79 a strange man who demonstrates how one may, with the help of the great art of advertising, keep the world’s newspapers attention year after year without having one single thing of interest to report. it’s simply a matter of knowing what sort of material the newspapers crave in order to satisfy the world’s spiritual needs— and in this area the man was truly great. (nansen 1920: 145) nansen recognized wellman’s skill at selling his project and maintaining the public interest and gave him credit for that. wellman probably deserves greater space in the history of the media than in the history of polar exploration. in their book on the history of the media in norway, bastiansen & dahl (2005) write about the telegraph, the press and film in their chapter about the great technological revolution between 1850 and 1920. wellman was an arctic pioneer in all of these areas: the newspapers’ telegrams documented the telegraph’s speed to the public. it was as if they said to the readers: if it is urgent, then use the telegraph. at the same time the telegraph had its influence on the press. the telegrams reinforced the newspaper’s role as a news medium; the transition from opinion-press to newspress was facilitated by the telegraph. (bastiansen & dahl 2005: 213; translated by the authors) according to capelotti, who has dug through the newspapers from the time wellman announced his plans for a north pole expedition, within three days of wellman’s announcement of the polar airship expedition in late 1905, the plan was greeted by newspapers across the country and around the world by a combination of comment that ranged from interested optimism to tolerant bemusement to open ridicule. (capelotti 1999: 117) the chicago record–herald ’s wealthy owner, victor lawson, sponsored wellman’s trip knowing that such material sold newspapers. among the newspaper stories capelotti tracked down, a comment printed in the cleveland plain dealer declared that, “whether walter wellman reaches the north pole or not there will be a lot of interesting news connected with the daring venture, and the newspaper that backs him is well aware of this fact” (5 january 1906; quoted in capelotti 1999: 119). many newspapers agreed on the fact that this was a great media event: correspondent walter wellman’s assignment to build an airship, proceed to the north pole and report by wireless is the biggest one yet. it even outdoes mr. bennett’s memorable order to mr. stanley to go to africa and find livingston. ( boston herald 3 january 1906, quoted in capelotti 1999: 119) in addition to attracting journalists and tourists and filling the newspapers with arctic material, wellman also managed to awaken the interest of the infant film business. according to capelotti, wellman’s “biographer”, e. b. baldwin’s diary of wellman’s expedition to franz josef land in 1898–99 mentions that a “cinematograph” was used to record their arrival in the arctic (capelotti pers. comm. 2006). wellman’s brother arthur reportedly filmed wellman’s dirigible taking off at svalbard in 1909, during a later attempt to reach the north pole (capelotti 1999, pers. comm. 2006). although wellman seems to have been aware of film’s potential, there is no evidence that wellman himself brought along a film camera to document his progress towards the north pole before the 1909 attempt. this is probably because wellman had made a deal with the warwick trading company, giving them the rights to film the 1906 expedition. a film with the title the wellman polar expedition is described in the second volume of rachel low’s history of british film (1997). according to low, the most important of all the expedition films “was that of the scott antarctic expedition, which may in fact be described as one of the really great achievements, if not the greatest, of british cinematography during this unhappy period” (low 1997: 155). she continues: it is not the first example of polar cinematography. the warwick trading company had sent an operator (j.h. avery) with the wellman expedition, which tried to reach the north pole by airship and motor sleigh in the summer of 1906, and had received 6000 ft of film by the autumn which, however, apparently proved unsatisfactory and were heard of no more. (low 1997: 155) one of the many short-lived trade magazines from the infancy of films, cinematography and bioscope magazine (1906–07) was published by the warwick trading company. the magazine made much of the coming film about wellman’s polar journey. in addition to some smaller notices about trials of the motor sleigh wellman had planned to bring along in the airship, the magazine ran two major articles about the planned film. the first article, in the may 1906 issue, was a combination of selfaggrandisement by the film company and a description of the agreement with wellman to participate in the expedition. the anonymously authored article, entitled “enterprise. the north pole this time”, boasts that no contemporaneous film companies had accomplished more “daring and enterprising exploits with the bioscope camera than warwick” and that “it is an indisputable fact that we have more negatives of natural subjects than any three other cinematographs put together” (1906: 33). after listing a number of grand journeys to canada, sudan, india and other countries, the article declares, “we hope to eclipse even this wonderful record” (1906: 33). it went on: by courtesy of walter wellman, esq. of the wellman chicago record–herald polar expedition, accommoda 80 polar research 26 (2007) 76 – 85 © 2007 the authors wellman’s 1906 polar expedition on film j.a. diesen & n. fulton tion has been made to allow one of our operators to accompany the expedition, to what we hope will be their destination, the north pole. as many of our readers are aware, the participators in this scheme are hopeful of carrying out their project by means of a gigantic air ship, in conjunction with motor sleighs, etc. the building of the air house and gas works, the putting together of the air ship, the trials, the departure, and, we hope, their successful return, should make one of the most unique series of animated pictures ever yet “bioscoped.” ( cinematography and bioscope magazine , may 1906: 33) towards the end, the article cites a story in a newspaper called the morning leader , which gave an overview of the members of the expedition: mr. wellman, who has been twice to the arctic, is the leader, and is assisted by major hersey. the expedition includes six americans, three frenchmen, one englishman (a cinematograph operator of the warwick trading company), and a number of norwegians. ( cinematography and bioscope magazine , may 1906: 35) the rest of the article described wellman’s plans and equipment. in the next issue of the magazine, in june 1906, it reported on the departure of the warwick trading company’s cameraman northwards to cover the expedition: our operator, mr. j. roseman . . . left london on may 25th to join the remaining members of the expedition at tromso [ sic ]. he had tons of baggage with him, which took three cabs to convey it to the station. about fifteen of our employees went to king’s cross to see him off; and as the train steamed out the station [ sic ], three rousing cheers were given, which nearly took the roof off. it was quite an exciting moment, and even our operator himself realised that he was commencing on one of the most perilous journeys of his life. on returning to the office, one of our men was successful in securing a prize-winning tram ticket. we cannot overlook this fact, as it seems an omen of success to our latest undertaking. ( cinematography and bioscope magazine , june 1906: 59) note that low (1997) gives the name of the warwick cameraman as j.h. avery, whereas the cinematography and bioscope magazine piece says it was j. roseman. is this a mistake or did two warwick cameramen travel to norway and svalbard to document wellman’s bid for the north pole? we don’t know. we do know that warwick also had cameramen at the royal coronation in trondheim—there were 18 in all—and the company’s magazine advertises two films from the royal journey around the country: one documenting the journey along the coast from molde to trondheim, and one of the coronation itself. a search of the adverts for new films in the trade magazine reveals that the company visited norway several times during the period in question: there was a film of the holmenkollen skiing events in 1907, one of some military manoeuvres and one about the production of ice! the foregoing excerpts from cinematography and bioscope magazine give a good indication of the resources the warwick trading company was willing to put into covering the polar expedition. but, as low wrote, there are no traces of warwick’s wellman film itself. however, in june the trade magazine advertised another film, entitled with the wellman polar expedition , as being for sale: with the wellman polar expedition. in our last issue we announced that facilities have been granted us to accompany the wellman polar expedition, which is attempting to reach the pole, by air-ship and motor sleighs. the film under review shows one of the latter, which has been christened by mr. walter wellman, a “mechanical dog”, being tested on the norwegian ice fields by the inventor, major henry b. hersey, one of the us government. it is seen drawing three other sleighs, the first one being the one used by nansen, the second one carrying petrol, and the third one a sleigh of the usual type. the front wheel is in the form of a drum which grips the ice, and the runners are absolutely flexible steel, which are built on an ankle joint, thus giving in any direction in going over uneven surfaces. the capabilities of this ingenious motor are well demonstrated as it passes on the screen. the next scene is extremely interesting and shows the motor hauling three logs of timber, which are equivalent to a load of 4,200 lbs. in the next view the motor is seen overcoming obstacles. the movement, as it runs over a mound of snow, is indeed very graceful and shows the advantages of the flexible runners already referred to. the motor also passes over a frozen sheet of water the surface of which has been melted by the sun. as it runs through the water the effect is very fine, and the reflections add considerably to the excellence of the picture. it then approaches in full view on the screen, an excellent portrait thereby being obtained of the inventor and driver. this is unquestionably a film that should be in every showman’s list, for it is full of intense interest, and will be admired wherever it is shown. the length is 200 feet and the price £ 5. ( cinematography and bioscope magazine , june 1906: 47) this detailed description does not jibe with what low, quoted earlier, had to say. according to her, the footage— 6000 feet of film received by the autumn of 1906—taken by the warwick cameraman, whoever he was, was “unsatisfactory” and was apparently not used (1997: 155). perhaps only limited segments of the warwick footage proved interesting and of good enough technical quality to be made into saleable short films, such as the j.a. diesen & n. fulton wellman’s 1906 polar expedition on film polar research 26 (2007) 76 – 85 © 2007 the authors 81 one described above, featuring the major’s “mechanical dog”. it is also possible that an accident befell the original footage, damaging much of it and thereby rendering it unusable. these are only guesses. footage of wellman’s polar expedition does survive in the british national film and television archives: the 1906 film, the wellman polar expedition—set out from bergen to spitzbergen . records in the archives attribute the film to the charles urban trading company and the cameraman is named as emile louis lauste, a frenchman. this is the film of which we have received a copy. according to the british film institute’s online guide to british film history, the american charles urban (1867– 1942) was an influential film producer and distributor in pre-war britain. he worked for the warwick trading company until forming the charles urban trading company in 1903, where he pursued his interest in actuality, travel and science films, as well as producing fiction films. the wellman polar expedition is listed in the british film institute’s online guide among several hundred films that urban’s company produced between 1903 and 1923. apart from this we have only one other contemporaneous reference to the film—an entry in the kinematograph and lantern weekly from 30 may 1907 (fig. 5), in which the urban trading company advertises a film of 500 ft made in the summer of 1906 about the wellman expedition entitled the wellman polar expedition. a visit to danes island . the advertisement proudly announces that the film is “the only animated picture record of the first attempt, in july of last year”. in the advertisement, a number of the subjects are described: in the arctic regions: hunting party leaving for the coast. panoramas of bergen, spitzbergen and the fiords.—life in a lapland village.—return from the hunt.—the steamer aground on a rock.—visit to danes island.—arrival at mr. wellman’s headquarters.—landing of the scientific party.—panorama of the camp.—group of lap guides.—mr. wellman leaving danes island etc., etc. this description corresponds well to the film in the british national film and television archives. the title of the 1906 film has been changed and a few feet have been added: the british national film and television archives film is 470 ft long, whereas the the kinematograph and figure 2 stills from the film. from top to bottom: saami people, northern norway; the spoils of a reindeer hunt, northern norway; the german coastal steamer, friesland , which visited virgohamna around 20 july 1906, at about the same time as the île de france ; wellman and a crowd of tourists at virgohamna in 1906. in the background of the last frame is pike’s house, built by the british sportsman arnold pike in the early 1890s and used by the wellman expeditions of 1894 and 1906–09 and the andrée expeditions of 1896–97. 82 polar research 26 (2007) 76 – 85 © 2007 the authors wellman’s 1906 polar expedition on film j.a. diesen & n. fulton lantern weekly advertises the film as being 500 ft in length. the 1906 film is eight minutes long and lacks intertitles, which was not unusual in films of this era (thompson & bordwell 2003). the scenes do not appear to have been edited entirely chronologically: there are sudden jumps from mainland norway to spitsbergen and back again to the continent. the 1906 film opens with tourists in horse-drawn carriages on their way to the top—we think—of ulriken, one of the mountaintops around bergen that was a tourist attraction at the time. next we see the harbour area of bergen, including the small laksevåg ferries and the part of town known as nordnes. after that we move rapidly up the norwegian coast with panoramic shots of sunnmøre and hjørungfjorden taken from a boat. suddenly, we find ourselves on spitsbergen, the largest island of the svalbard archipelago, with its snowy mountains reaching right down into the sea. the next scene is a longer composition in which we see tourists in ships’ rowboats being set ashore on a desolate beach. there are no snowy mountains here: in the background are barren coastal cliffs. this is obviously a hunting expedition in mainland norway: a good number of the party carry rifles. there is even a horse in one of the boats. the film then cuts to an indigenous dwelling with saami families posing for the camera (fig. 2), holding up reindeer antlers, ad with children in traditional garb and so on. then the film cuts back to the hunting party, which is returning to the boats with their quarry—half a dozen reindeer (fig. 2). then we are back on spitsbergen and in kongsfjorden (king’s bay). we see a boat moving through drift ice in towards the bay of virgohamna, on the small island of danskøya off north-westernmost spitsbergen. we see more ships in the vicinity of the harbour—these are the german friesland (fig. 2), according to the synopsis on the british film institute’s website, and the norwegian frithjof (capelotti, pers. comm. 2006). there then follows a number of scenes from the camp in virgohamna. we see tourists being set ashore, figure 3 more stills from the film. from top to bottom: the base camp at virgohamna built by the wellman expedition in the summer of 1906, with the machine shop and hydrogen generator to the left and the chicago record–herald house (also called the wellman house), with the american flag, to the right; wellman examines the cairn monument built on the site at virgohamna where the swedish balloonist salomon a. andrée lifted off in july 1897; the tent at virgohamna where wellman found german newspaper correspondent (and nominal spy: see capelotti et al. 2007 [this issue]), otto von gottberg; wellman tips his cap to the camera as a small steam launch takes him to a waiting passenger liner anchored offshore— as described in the excerpt from tromsøposten , this may have been in order to meet the passengers over dinner. j.a. diesen & n. fulton wellman’s 1906 polar expedition on film polar research 26 (2007) 76 – 85 © 2007 the authors 83 wellman onshore (fig. 2), a long pan showing the wellman house with its american flag (fig. 3), the camp of the german journalist, otto von gottberg, the memorial stone for andrée’s balloon expedition, and scaffolding for the balloon hangar. the film cuts to close-ups of the members of the expedition, wellman taking notes at andrée’s memorial (fig. 3) and gottberg conversing with tourists (fig. 3), before the film ends with close-ups of wellman as he is rowed out to one of the tourist ships (fig. 3) while he smiles and doffs his cap to the cinematographer. emile lauste, the camera operator on this film, was an experienced cinematographer. according to the records of the british film institute, he worked on 11 other films, mostly documentaries, between 1898 and 1922. with one exception (a german film), the films were produced by british production companies, and two of them were for the charles urban company: the wellman film and a film of the zambezi river and victoria falls. lauste may well have worked on many more films than those in the british film institute’s records. yet there is nothing to indicate that the charles urban company’s wellman film was made in close cooperation with the expedition itself. it lacks the intimacy and detail that one would expect from a film that enjoyed the kind of filming rights that the warwick trading company boasted about in its magazine. we conclude that this film in fact records a tourist trip up the coast of norway and on to virgohamna. this explains why the pictures appear to be taken from a respectable distance: the photographer, although working to professional standards, was working from the vantage point of a tourist. on 28 august, tromsøposten printed a lengthy telegram about the journeys of the norwegian tourist ships neptun and kong harald to spitsbergen (fig. 4). the ships sailed to the margin where open sea met pack ice at 81 ° n; passengers viewed whale carcasses about to be processed at bellsund and visited the coal mines at adventfjorden. a hunting trip took place in sassenfjorden. the climax of the trip was a 10-hour stop in virgohamna: wellman and the other participants of the expedition gave us a charming reception. we were afforded the opportunity to inspect everything. the colossal balloon-shed, whose skeleton is nearly fully erected, as well as machines and equipment, the site and remains of andrée’s balloon-shed, mr. pike’s house . . . wellman and major hersey, the expedition’s american participants, were invited to dinner onboard the kong harald . some especially interested passengers from the neptun were also invited . . . passengers immediately seized glasses, cups and spoons used by wellman while he was onboard and then demanded certificates authenticating their spoils. after dinner, wellman visited the neptun . the passengers of both ships gave large ovations upon his de-embarkation. the general impression from conversations with wellman was that an ascent this year, while not out of the question, all the same was considered unlikely, due to delays in the work caused by inclement weather conditions. it is most likely that the expedition will leave towards the end of september, leaving behind them a number of engineers and workers to take care of everything until next summer. photographers and amateurs from the ranks of the passengers of both vessels take a large figure 4 an advertisement for a tourist cruise in the newspaper trondhjems adresseavis , 10 august 1906. note the mention of “danes gate (starting point for wellman’s polar expedition)”. 84 polar research 26 (2007) 76 – 85 © 2007 the authors wellman’s 1906 polar expedition on film j.a. diesen & n. fulton amount of photographs. favourable group photographs were taken of the passengers of both ships as well as andrée’s stone with all nations’ flags. 8 degrees below zero at the edge of the pack ice. overwhelming impression. ( tromsøposten 28 august 1906) the neptun and the kong harald were only two of the numerous ships that stopped in at virgohamna that summer so that tourists could gawk at the wellman show, taking photographs and perhaps pocketing a souvenir. during the summer of 1906, tourist ships from britain, finland, france and germany, as well as a dozen ships from norway, arrived at the wellman camp (melding fra poststyrelsen 2007). among the passengers of the french vessel, the ss île de france , arriving 14 july, was emile lauste, the cameraman from the charles urban trading company. we are left with unanswered questions. why did charles urban make a film about the wellman expedition, when the warwick trading company had already made a special arrangement with wellman, and what was the the fate of the much-touted warwick footage? according to mckernan (1999), urban was engaged in disputes with his former employer for several years after he left the warwick trading company in 1903. we can therefore speculate that urban was simply motivated to make and distribute moving pictures of wellman before his rival did. the next summer there weren’t quite as many tourist ships at virgohamna. although he tried again, wellman never made it to the north pole and there is nothing to suggest that either charles urban or the warwick trading company sent anyone to svalbard after 1906. acknowledgements we are grateful to prof. peter capelotti and friends and colleagues from the british silent cinema festival, especially bryony dixon, of the british film institute, and film researchers jude cowan and tony fletcher. figure 5 an advertisement in the kinematograph and lantern weekly , 30 may 1907. j.a. diesen & n. fulton wellman’s 1906 polar expedition on film polar research 26 (2007) 76 – 85 © 2007 the authors 85 references anonymous cinematography and bioscope magazine , may 1906: 33 , p. 33. bastiansen h.g. & dahl h.f. 2005. norsk mediehistorie. (norwegian media history .) oslo: universitetsforlaget. bergens tidende 1906. wellmanekspedition . (the wellman expedition) 18 july, p. 2. bergens tidende 1906. hvem er walter wellman ? (who is walter wellman?) 20 july, p. 1. british film institute. urban, charles (1872–1942). in screenonline: the definitive guide to britain’s film and tv history . accessed on 21 january 2007 at http://www. screenonline.org.uk/people/id/514893/. british film institute. online film and tv database. pages http://ftvdb.bfi.org.uk/sift/title/69637?view = synopsis and http://ftvdb.bfi.org.uk/sift/individual/81362 accessed on 21 january 2007. capelotti p.j. 1999. by airship to the north pole. an archaeology of human exploration . new brunswick: rutgers university press. capelotti p.j., van dyk h. & caillez j.-c. 2007. strange interlude at virgohamna, danskøya, svalbard, 1906: the merkelig mann , the engineer and the spy. polar research 26 , 64–75. cinematography and bioscope magazine 1906. enterprise. the north pole this time. may, p. 33. cinematography and bioscope magazine 1906. with the wellman polar expedition. june, p. 47. cinematography and bioscope magazine 1906. the wellman polar expedition. our operator leaves london. june. pp. 57–59. drivenes e.-a. & jølle h.d. 2004. norsk polarhistorie— ekspedisjonene. (norwegian polar history—the expeditions .) oslo: gyldendal. kinematograph and lantern weekly 1907. advertisement for urban production’s film. 30 may, p. 34. low r. 1997. history of the british film 1906–1914 . vol 2. london: routledge. mckernan l. 1999. a yank in britain: the lost memoirs of charles urban, film pioneer . hastings, east sussex: the projection box. melding fra poststyrelsen om oppretting og drift av “postaabneri” i advent bay paa spitzbergen. (announcement from the postal service about the establishment of “postaabneri” in advent bay, spitsbergen.) accessed on 18 january 2007 at http://home.online.no/~polar-ps/ adventbay.html. nansen f. 1920. en ferd til spitsbergen. (a journey to spitsbergen.) kristiania (oslo): jacob dybwad’s publishing house. thompson k. & bordwell d. 2003. film history: an introduction . boston: mcgraw-hill. tromsøposten 1906. om spitsbergenturene med “neptun” og “kong harald”. (on the journeys to spitsbergen with the neptun and the kong harald .) 28 august, p. 2. tromsøposten 1906. den styrbare. i det parisiske ballonverksted. (the dirigible. at the parisian airship builder’s workshop.) 23 june, p. 1. trondhjems adresseavis 1906. 10 august. http://www http://ftvdb.bfi.org.uk/sift/title/69637?view http://ftvdb.bfi.org.uk/sift/individual/81362 http://home.online.no/~polar-ps/ the physiology of polar marine zooplankton* andrew clarke and lloyd s. peck clarke, a. & peck, l. s. 1991: the physiology of polar marine zooplankton. pp. 355-369 in sakshaug. e.. hopkins. c. c. e. & britsland. n. a . (eds.): proceedings of the pro mare symposium on polar marine ecology. trondheim. 12-16 may 1 9 0 . polar research 10f2j. the polar marine environment is characterised by low stable temperatures with seasonal variations ranging from 23°c at lower latitudes to only ?0.2”c at high latitudes. the arctic basin is dominated by multi-year ice. whereas the antarctic is subject to large seasonal changes in the cover by annual sea ice. primary production is intensely seasonal nearshore but probably less so in offshore waters where significant production is associated with the marginal ice zone. oxygen consumption in polar zooplankton is low compared with temperate and tropical species. annual growth rates are generally slow and, especially in herbivores, highly seasonal. it is likely that fast growth rates are possible for polar zooplankton in areas of high food availability such as ice-edge blooms. but these growth rates are not usually achieved in the more oligotrophic open-ocean areas. lipid stores in polar herbivorous zooplankton are generally high, although some euphausiids and gelatinous zooplankton also rely on degrowth to provide energy over winter. ice-edge blooms are of great importance to the polar marine food web although the quantitative significance of winter feeding under ice has yet to be resolved. comparison of data on lipid storage and oxygen consumption for polar zooplankton indicates that there are large differences in the energy requirements of benthos and crustacean zooplankton. this is probably related to the high metabolic cost of staying in the water column. in contrast gelatinous zooplankton (salps, ctenophores. medusae and siphonophores) have a low energy throughput, related to a body composition which renders them essentially neutral in buoyancy and a slow but efficient means of locomotion. under good feeding conditions many species can therefore grow and reproduce very rapidly. this emphasises the distinct energetic regime of gelatinous zooplankton, now known to be a group of major ecological importance in most waters of the world. andrew clarke and lloyd s . peck. british antarctic survey, high cross. madingley road. cambridge cb3 oet. uk (revised january 1991). introduction the cold waters of high latitudes have long inter ested physiologists because they represent one extreme of the range of conditions to which mar ine organisms have become adapted. although it is natural from an anthropocentric viewpoint to assume that polar waters somehow represent a harsher environment than the apparently more equable waters of the tropics, this is not necess arily the case (clarke & crame 1989). a large amount of physiological and bio chemical work has been undertaken on polar , marine organisms and a complete review is beyond the scope of this paper. we have chosen instead t o examine a number of related topics with the common theme of energy storage and utilisation. we shall contrast the arctic and ant’ arctic where appropriate, using examples from both hemispheres, and attempt to highlight out * keynote lecturc presented at the pro marc symposium on polar marine ecology, trondheim, norway. 12-16 may 1990. standing problems. first, however, it is necessary to outline the relevant features of high latitude marine environments and the organisms that live there. the polar marine environment although the arctic and the antarctic marine systems are often treated together, they differ in many ways. both are cold and covered by sea ice for much of the year, but they differ in extent, topography, oceanography and age. in both areas seawater temperatures are low and frequently reach 1.9”c. seasonal variations in temperature are also small, although the amplitude is greater towards lower latitudes and is always more sub stantial in surface waters. a summer thermocline may develop but the generally stormy nature of these latitudes means that wind-induced mixing often extends to considerable depths. some areas are both exceptionally cold and stable. at mcmurdo sound, antarctica, the maximum annual temperature range is only ko.2”c either 356 a . clarke & l . s . peck side of -1.7"c (littlepage 1965), making this one polar zooplankton of the most thermal$ stable areas on earth. both the southern ocean and the arctic basin are subject to sea ice but the nature of this ice differs in the two areas. in the southern ocean the ice is almost exclusively annual sea ice (pack ice). a synthesis of data from satellite imagery for 1973-1976 revealed a maximum cover of about 20 x lo6 km? in september and a minimum of about 3 x lo6 km2 in february, although there were considerable year to year variations (zwally et al. 1983). the arctic differs i n that the bulk of the sea ice is multi-year ice and even at the sum mer minimum 45% of the surface (roughly 6.5 x lo6 km?) remains ice-covered. in winter this increases to about 12.5 x 10" km2 so the overall seasonality of the sea-ice cover is much less than i n the southern ocean (parkinson et al. 1987). in both hemispheres the high latitude oceans show an intense seasonality of primary produc tion. this is particularly marked in nearshore waters where summer chlorophyll standing stocks can exceed 50 mg/m3. although maxima of about 20mg/m3 are more typical (clarke et al. 1988; holm-hansen et al. 1989). the situation in the open ocean is more complex. oceanic water blooms rarely reach the concentrations found closer inshore, and the distribution of phyto plankton biomass is patchy. in the southern ocean, open water blooms only occasionally dev elop to levels where nutrients are depleted, and ' peak standing crops of 1-4mg/m3 are typical. the reasons for this are not fully understood, although the lack of water column stability because of the stormy conditions is generally accepted as the most likely explanation (priddle et al. 1986). the role of grazing (both by macro zooplankton and microbial consumers) in limiting phytoplankton standing crop is still highly con tentious (smetacek et al. 1990). much higher standing crops, although still , below those found in nearshore waters, are found associated with sea ice. however two aspects of sea-ice associated primary production are of importance to polar zooplankton. the first is the bloom associated with the water column stability induced by the receding ice front (sullivan et al. 1988), the second is the possible role of under-ice grazing in supplying energy to zooplankton during the winter. the quantitative importance of this to adult zooplankton is still unclear but the sig nificance to larval stages may be great (daly & macaulay 1988; marschall 1988; ross et al. 1988). organisms living in the sea vary in size from viruses t o whales, a scaling range of more than nine orders of magnitude. for the purposes of this review. however, we will limit ourselves t o the conventional macroplankton (invertebrate zooplankton greater than 1 mm in size). although many taxa have been investigated by physiologists over the years, most work has concentrated on crustaceans. particularly copepods and euphau siids. we will therefore concentrate our discussion on these groups, touching on other organisms where relevant. through the examination of data on growth rate, oxygen consumption, and energy storage, we attempt t o distinguish the effects of temperature from those of seasonality, and we will conclude by contrasting the physiological ecology of zooplankton and benthos i n an attempt to set these results in a (somewhat speculative) framework. oxygen consumption measuring the oxygen consumption of zooplank ton presents a number of technical difficulties that are not always easy to overcome. these centre on the need to confine within a small space an organism adapted to an essentially limitless three dimensional environment. the major problems are controlling for handling stress and locomotor activity, but a variety of other influences render oxygen consumption one of the most difficult physiological variables to measure in a meaningful way (see discussion in childress 1977). it is usual for marine physiologists to separate the costs of locomotor activity (active metab olism) from those of maintenance (basal, resting or standard metabolism). routine metabolism (the oxygen consumption of an organism at an activity level representative of normal existence) falls somewhere between these two extremes. routine metabolism for a benthic invertebrate or demersal fish thus includes the costs of foraging, searching for mates, vigilance and so on. for a pelagic organism which must expend energy to remain in the water column, these distinctions are less helpful. it could be argued, for example, that some fractions of the costs of locomotor activity should be included in basal metabolism, for with o u t this activity the organisms would drop out of the water column and die. in polar species these difficulties of definition may be compounded by an overall low rate of oxygen utilisation. in practical terms all these various difficulties together mean that different measurements on the same animal can give some what different results. clearly, even when the influence of the experimenter has been minimised there is no such thing as a definitive respiration rate for any marine invertebrate. nevertheless there is a need for some form of representative value to use in energetic calcu lations, o r for comparison with other species. the major problem here is the influence of locomotor activity on oxygen consumption, for direct measurements of activity costs in large crus taceans have suggested that these costs are sub stantial (torres et al. 1982; torres & childress 1983). since few reports of the oxygen con sumption of marine zooplankton give any infor mation on activity, the only practical approach with presently available studies is simply to accept the data we have and look for broad trends. one of the comparative aspects of respiratory physiology that has attracted much attention has been the relationship between respiration rate and temperature. there are two important aspects to this relationship. the first is the effect of acute tem 0.4 h k 5 0.3 y 5 .5 5 5 s 0.1 $ c q 0.2 v ) 0 0 0 physiology of polar marine zooplankton 357 perature change on metabolic rate, the second is the nature and extent of evolutionary adaptation to temperature. in general, following an acute rise in temperature, metabolic rate increases essentially in respone to thermodynamic con straints. this acute effect may be modulated by periods of acclimation prior to making any measurement. although there have been a few indications of unusually high temperature sen sitivity in polar marine zooplankton (that is, high q l o values), these have generally not been sub stantiated when studies are confined within a reasonable temperature span, when q l o values are usually within the normal biological range of 1 to 4. of wider interest is the rate of oxygen con sumption of polar zooplankton in relation to species from lower latitudes. this topic has been reviewed recently (clarke 1991) and so will only be outlined here. several authors have pooled data from many studies and looked for tem perature (and hence latitudinal) trends. the results are summarised in fig. 1. although the individual relationships differ in temperature sen sitivity (table l), the overall pattern is clear: polar marine invertebrates have a lower oxygen consumption than species from warmer waters. there is no evidence that the costs of growth or i i i i 1 0 10 20 30 i i temperature (“c) fig. 1. the relationship between respiration rate and tcmperature in different groups of marine organisms. 1 = zooplankton (ikeda 1974). 2 = zooplankton (ikeda 1985). 3 = crustaceans (ivleva 1980). 4 = non-idothcid isopods (luxmoore 1984). from clarke (1991). 358 a . clarke & l . s . peck table i . temperature and respiration in marine invertebrates (from clarke 1 9 9 1 ) . range ("c) over group q,,i which q,,, calculated rcferencc zooplankton i .76 1 . 5 to 28.5 ikeda 1970 zooplankton i 63 i .1 to 30 lkeda 1985 crustaceans 2.27 0 to 30 lvleva 1980 isopods 2.98 1.5 to 25 luxmoore 1984 gastropods 2.13 1 7 to 30 houlihan & allan 19x2 locomotor activity vary with temperature (although the effect of viscosity, which itself varies with temperature, o n the cost of locomotion should not be ignored). t h e most likely expla nation of the shape of these curves is thus a variation in the cost of basal (maintenance) metabolism with temperature (clarke 1983. 1987a, 1991). precisely what physiological pro cesses constitute basal metabolism is not clear, but current data suggest that major components are protein turnover, cardiovascular, and osmotic work. it would clearly be of value t o see how the rate of these processes varies with latitude. possible correlates of these reduced metabolic costs at low temperature include a reduced annual energy requirement, an increased ecological growth efficiency (clarke 1987b), and a reduced requirement for an overwintering energy store. growth rate i t has been known from the earliest studies of polar organisms that high latitude marine invert ebrates tend to grow slowly compared with those from lower, warmer water latitudes (clarke 1983, 1988; siege1 1987). a corollary of these slow overall growth rates is that lifetimes are often long and reproductive maturity is often delayed. why d o polar marine invertebrates grow slowly? t h e initial. intuitively appealing expla nation was that the processes of growth were simply slowed by the low temperatures. this hypothesis was later superseded by a more com plex explanation involving a relatively high basal metabolism at low temperatures resulting in pro portionately less energy being available for growth (so-called metabolic cold adaptation). neither of these explanations now appears to be correct. there is an enormous volume of litera ture showing clearly how within a given species of fish or aquatic invertebrate growth can be reduced by lowering the temperature and increased by increasing the ration levels (see cushing 1975 for a series of examples for fish). these results a r e often mistakenly extrapolated t o the polar environment and used t o explain the slow growth of polar marine organisms simply o n the grounds that the water is cold. this however seems unlikely given the extensive (though not always perfect) compensation for temperature which has been achieved in many physiological processes (see clarke 1991 for a review). meta bolic cold adaptation is also unlikely t o provide an explanation for slow growth since the low resting oxygen consumption of polar marine invertebrates (fig. 1) would rather suggest that more, not less, energy is available for growth. o n e of us recently proposed that slow growth is caused principally by seasonal resource limitation (clarke 1988). this hypothesis is difficult to test, for if an animal is shown to b e growing slowly it is often impossible t o tell whether growth is being limited by temperature or food (for a more detailed explanation of this point see clarke 1991; clarke & north 1991). t h e difficulty here is t o decide whether polar marine organisms have been able t o evolve compensation for temperature in the growth process; in other words, how fast can they grow when food is available? fortunately the seasonal nature of the polar marine enviroment allows us to examine this point. if growth in polar species is limited by food rather than temperature, we can make the following two predictions: 1. growth will be seasonal in herbivores, and less seasonal in carnivores (reflecting the differing patterns of seasonal abundance in their food). 2 . growth rates of polar species in the presence of excess food will be comparable with those of related temperate or tropical species under similar conditions. the second prediction is difficult t o test, for non physiology of polar marine zooplankton 359 with obligate herbivores having growth (and in many cases reproduction) tightly coupled to the summer phytoplankton bloom, and carnivores often (but not always) decoupled. limiting food is a most unusual ecological situation in the sea, and many other constraints or con founding factors may intervene. it may be poss ible to test this prediction experimentally with larval or juvenile stages fed ad lib. in the labora tory (clarke & north 1991). a more practical approach however would be to test a third pre diction: 3. maximum growth rates will be comparable with those of similar or related species from warmer waters. seasonal growth strongly seasonal growth is shown by many species of polar euphausiid including meganycti phanes noroegica (bbmstedt 1976; falk-petersen 1981), thysanoessa inermis, t . raschii (falk-pet ersen 1981), euphausia superba and to a lesser extent e . triacantha (baker 1959; siegel 1987). more rapid growth in summer has also been reported in the mysid antarctomysis maxima (ward 1984), the salp salpa thompsoni (foxton 1966) and the amphipod themisto gaudichaudii (kane 1966). many polar copepods overwinter as late cope podite stages (frequently civ or cv), with matu ration, egg production, and the early copepodite stages being confined to summer. representative examples are calanus glacialis from the arctic (tande et al. 1985) and calonoides acutus from the antarctic (andrews 1966). voronina et al. (1980a) have modelled the seasonal pattern of growth in calanoides acutus, showing how pro duction is limited essentially to just five months of the year. although the life cycle model on which this analysis was based is somewhat sim plified, the results demonstrate very clearly the intensely seasonal production typical of high lati tude herbivorous zooplankton. some carnivorous species (for example euchaeta spp.) produce eggs during winter, but this is at the expense of pre viously stored lipid reserves (clarke 1983). species without strongly seasonal growth tend to be carnivorous; a good example is the chae tognath sagitta gazellae (david 1955). chae tognaths follow the seasonal migration of their copepod prey and their impact on the over wintering copepod population can be substantial (0resland 1990). overall these observations are precisely what would be expected from a food-limited system, maximal growth rate the seasonal growth of many species suggests that at the height of the production season instan aneous growth rates may be quite high. unfor tunately the nature of much biological oceanographic research makes this difficult to test. samples are usually taken only over a short time period in any one body of water and so a more general picture over a longer time span can be obtained only by combining many data sets. as a result, spatial and temporal detail is blurred by sampling error, geographical variation, and year to year differences. this point is neither new nor original, but it is germane to an understanding of data on zooplank ton growth rates. it emphasises that the only way to obtain unequivocal growth rate data for a population is to obtain frequently spaced sequen tial samples from a single population. this is not a simple task in the open ocean, and so it is not surprising that one of the best examples comes from the study of the major zooplankton in balsfjorden, northern norway. samples were taken monthly and the growth and biochemical composition of three euphausiids and two cope pod species were followed throughout their life cycles (falk-petersen 1981; hopkins et al. 1984). in 0-group t,hysanoessa inermis there was no growth over winter but growth was extremely rapid once the phytoplankton bloom got under way. dry mass peaked in september and then declined significantly (degrowth) over winter, fol lowed by further growth in the subsequent summer. a similar picture was found for the sympatric t . raschii (fig. 2 ) . the herbivorous copepod calanus finmarchicus reached asymp totic wet mass within two months of spawning, and the carnivorous metridia longa within three months (hopkins et al. 1984). these results indicate that instantaneous growth rates of polar zooplankton can be quite high. most data from oceanic populations, however, suggest slower growth rates. antarctic euphausiids and mysids frequently show slow growth overall, and the fastest summer rates are not as rapid as those reported from balsfjorden (ward 1984; siegel 1987). 360 a . clarke & l . s. peck 40 30 y ? v) v) e" 2 20 n 10 i l r l l , l , r , l l l l , , , , j a s o n d j f m a m j j a s 6 1976 1977 fig. 2. growth (dry mass. mg) in two euphausiids from balsfjorden. northcrn norway. a . thysunoessu inermis. b. thysmioessn raschii. redrawn from falk-petersen (1981). the two symbols indicate differcnt year-classes sampled at the same time: the graphs thus do not represent continuous growth by a single cohort. the vertical scale means that winter degrowth is not clearly visible. a more varied picture is presented by studies of oceanic copepods. for example in calanoides acutus from the southern drake passage the rate of development for early copepodite stages is about one month per stage (huntley & escritor 1991). a similar growth rate has been reported from ezcurra inlet, king george island (chojnacki & weglenska 1984). other recent studies from slightly warmer waters further north have indicated, however. that faster rates are quite possible. data for calanoides acutus obtained by andrews (1966) during the discovery investigations indicate that passage through the early copepodite stages (ci to chi) may take place within a single month (atkinson 1989). this is supported by samples taken by rrs william scoresby and rrs discovery i1 in 1928-1951 from the southern ocean, and also the population structure proposed by voronina et al. (1978), which indicates that passage through the early copepodite stages of calanoides acutus and cal anus simillimus may be achieved within only four to six weeks (atkinson 1991). growth rates of several copepod species around south georgia also appear to be high, although the data here is not conclusive (atkinson 1989). we cannot conclude from these analyses that all polar zooplankton are capable of rapid growth under the right circumstances, but the evidence is suggestive. two points are worth making in this context. the first is that the ability to grow fast in polar waters would indicate a substantial (but not necessarily perfect) degree of temperature compensation in growth rate. this has been sug gested for calanus finmarchicus (matthews 1968) and also in populations of estuarine harpacticoid physiology of polar marine zooplankton 361 further review will not be attemped here. fol lowing are the major points that have emerged over the past 15-20 years: copepods along a latitudinal cline alone the east ern seaboard of the united states (lonsdale & levinton 1986). the second point is that growth rate would be expected to vary from place to place, and from year to year, because of differences in food avail ability. copepod egg production has long been known t o respond to food level both in the field (gatten et al. 1980) and in the laboratory (hirche 1989, 1990). demonstrating a response in growth rate is more difficult, but this has recently been shown clearly for seven species of cladoceran by gliwicz (1990), and has long been known for fish (see cushing 1975 for an excellent series of examples). overall we must conclude that although there is some evidence that polar zooplankton can achieve fast growth rates in some areas, we cannot confirm that these rates are fully comparable with those in species from warmer waters. if food availability is the primary driving force in deter mining field growth rates in polar zooplankton, this would explain why open-ocean growth rates are generally slower than those in animals associ ated with ice-edge blooms, and why production cycles tend to track the retreat of the ice edge (vorinina et al. 1980). in the more oligotrophic open-ocean areas it is probable that the potential for fast growth present in polar marine zooplank ton is simply not realised. similar considerations apply to carnivorous species such as pteropods, chaetognaths, amphipods, and gelatinous species which prey on the herbivores feeding on the ice edge bloom. we urgently need of more physio logical measurements from zooplankton sampled during the production season at the ice-edge. energetics during winter the intense seasonality of primary production in the polar oceans means that food for herbivorous zooplankton is severely limited in winter. many species thus enter a non-feeding mode and over winter at depth, utilising lipid reserves synthesised the previous summer. these reserves may be used to fuel both maintenance metabolism and the production of eggs to be spawned at the beginning of the next bloom. the lipid reserves of polar zooplankton have been reviewed on several occasions (clarke 1983, 1984a; bimstedt 1986; hagen 1988), and so a 1. polar copepods (summarised by bimstedt 1986) and euphausiids (falk-petersen 1981) tend to synthesise larger lipid stores than species from warmer waters at lower latitudes (fig. 3). this is because the effect of the increased seasonality of food availability for herbivores at high latitudes outweighs the ben efits to be gained from a reduced maintenance metabolism (fig. 1) and hence necessitates a greater overwintering energy reserve. 2. lipid stores tend to be wax ester (we), especially in copepods, although triacylglycerol (tag) is frequent and alkyldiacylglycerol also found in some species (clarke, 1984a; hagen 1988). it is noteworthy that the polar fresh water copepod pseudoboekella poppei stores t a g rather than we (clarke et al. 1989), and this may be general for freshwater zooplankton (morris 1983, 1984). 3. carnivorous zooplankton tend to synthesise smaller lipid reserves than herbivorous species, though exceptions d o occur (for example car nivorous copkpods and amphipods can both be rich in lipids). the function of the lipid stores in chaetognaths and some gelatinous zooplank ton is unknown. they may serve as energy reserves, an aid to buoyancy, or may represent a way of sequestering excess lipid from the diet (clarke 1984a; hagen 1988; larson & harbison 1989). 4. benthic species tend to have low lipid contents. although in many species maturation of the ovary increases the lipid content, the latter never reaches the levels found in zooplankton (clarke 1983, 1984b). most measurements of zooplankton lipid reserves have been spot measurements. there have been few seasonal studies although these are necessary for elucidating the role of lipid reserves. important studies are those of littlepage (1964) on euphausia crystallorophias and euchaeta ant arctica at mcmurdo, and falk-petersen (1981) on euphausiids in balsfjorden, northern norway. although utilisation of lipid reserves is the most obvious mechanism used to supply energy over winter in polar zooplankton, some euphausiids appear to utilise body protein. this results in a loss of mass (degrowth) during winter. degrowth 362 a . clarke & l . peck fig. 3. the lipid content ( % dry mass) of copepods from high (polar). intermediate and low latitudes. species have also been subdivided into shallow (0) and deep (0) water forms. redrawn from birnstedt (1986). itself based on clarke (1983) and the initial diagram of lee & hirota (1973). has been clearly demonstrated in several arctic species (falk-petersen 1981; bbmstedt 1976) and in the laboratory for euphausia superba (ikeda & dixon 1982). whether degrowth occurs i n the wild in the latter species is unclear, although ettershank's analysis (1983) of samples taken in winter by stepnik at arctowski station, king george island, strongly suggests that i t does. the role of sea ice the potential importance of sea ice to the ecology of polar zooplankton has long been recognised. however it is only in the last ten years that the complexity of this interaction has been realised (carey 1985). it is not within the remit of this paper to review the interaction of zooplankton and sea ice. but several points are germane to polar zooplankton physiology: 1. it is likely that ice-associated blooms represent the best feeding conditions encountered by open-ocean (as distinct from nearshore) polar 2 . zooplankton. the fastest growth rates and/or largest reproductive output will therefore be found in these areas. this will apply alike to herbivorous species and the predators (both invertebrate and fish) that consume them. the precise quantitative importance of ice-associ ated biological activity in the overall pattern of carbon and energy flow in polar oceans has yet to be established, but current evidence suggests i t is substantial. sea ice may contain a significant biomass of microbial organisms at, or close to, its lower (sea water) interface. this is used as a source of food by a range of zooplankton including copepods, arnphipods, and euphausiids; pred atory organisms such as ctenophores have been noted feeding on these herbivores. again the precise quantitative importance of this system is unknown, although i t has been proposed that ice algae may be of vital significance to the over winter survival of larval and immature euphausia superba (daly & macaulay 1988; marschall 1988; ross et al. 1988). physiology of polar marine zooplankton 363 h v) 2 60 e p 2p ti 4 0 c q c a comparison of the energetics of plankton and benthos in this final section we will attempt a broad-brush picture of the energetic differences between living in the water column and living on the sea bed. this will inevitably be somewhat speculative, but we believe that the intense seasonality at high latitudes accentuates this contrast, highlighting patterns which although present at lower latitudes may not be so clear there. we shall examine in turn lipid storage, oxygen consumption, and total energy flux. lipid storage we have already highlighted the tendency for polar zooplankton to have larger lipid reserves than related species from lower latitudes (fig. 3). in fig. 4 we have plotted all the lipid data for polar marine invertebrates known to us, with data for plankton and benthos grouped separately. because of possible differences in the pattern of food availability, we have also separated each category into herbivores and omnivores/ 8o r 8 carnivores, making a total of four basic categories. in general those polar benthic herbivores that have so far been examined have low lipid contents. the lipid contents of benthic carnivores are somewhat higher, but still lower, than plank tonic herbivores. pelagic invertebrates show a range of lipid contents and composition. these vary from the low amounts of lipid dominated by triacylglycerol in gelatinous species, chaeto gnaths, and the predatory annelid vanadis ant arctica, through intermediate levels (amphipods) to the very high lipid contents dominated by wax ester typical of calanoid and euchaetid copepods. part of this variability is undoubtedly associated with size and developmental stage. smaller species tend to have higher percentage lipid con tents and this may be due in part to mass-specific metabolism being higher in smaller organisms. a similar difference in tissue energy con centration between benthos and plankton in kos terfjord, sweden, was demonstrated by norrbin & bamstedt (1984). they found that when organisms were classified according to tissue energy content (expressed as cal/mg afdm), there was almost complete separation of benthic 0 0. 0. h o k h o/c benthos plankton fig. 4. lipid contents (% dry mass) for high latitude benthic and pclagic marine organisms. open symbols denote herbivores and closed symbols carnivores/omnivores. the data for gelatinous zooplankton are shown as squares. the data arc from lkeda (1972). lee (1974. 1975). clarke (1977, 1984a. b). percy (1979). bbmstedt (1980. 1986). pcrcy & fife (1981). sargcnt & falk-petersen (1981). lawrence & guille (1982). falk-petcrscn ct al. (1982). and larson & harbison (1989). note that many data points overlap, modified from an unpublished manuscript by peck & clarke. 364 a . clarke & l . s. peck and planktonic species. the planktonic species had the more energy-rich tissue, and norrbin & bgmstedt suggested this was due to the high lipid contents of many planktonic marine organisms. low energy contents were also found in 121 species of arctic benthic invertebrate by wacasey & atkinson (1987). these suggestions are con firmed by the data summarised in fig. 4. oxygen consumption in fig. 5 we have undertaken a similar analysis on all the measurements of the oxygen con sumption of polar marine invertebrates known to us. a major difficulty with this type of com parative study is allowing for the (sometimes very large) differences in size of the various organisms. for each species an absolute oxygen consumption was calculated from published data, for the middle of the size range over which measurements were made. where the original data were pre sented in volume terms, these were converted to molar units assuming stp. the absolute rate was then divided by the dry mass of the animal to loor produce a representative mass-specific rate of oxygen consumption. this does not remove the effects of size, for in most organisms mass-specific metabolic rate itself varies with size. however, the effect is relatively small. a comparison of the metabolic rates of the four species groups in fig. 5 indicates that a clear distinction can be drawn between benthic and planktonic species. on average, the metabolic rate of a typical planktonic species exceeds that of a typical benthic species by a factor of about x 6. since polar metabolic rates in general are low (fig. 1). this emphasises that the metabolic rates of many polar benthic species are generally very low indeed (see, for example. peck et al. 1986). this factor is, of course, an average value; it is clear from fig. 5 that comparative studies of selected benthic and planktonic forms might reveal factors either much larger or smaller than x6. some of the variation in fig. 5 will be related to differences in size. however the allometric exponent for mass-specific metabolic rate (gen erally of t h e order of 0.2-0.3) is too small to apco(> 100) h oic h o/c benthos plankton fig. 5. respiration ratcs of high latitudc benthic and pelagic marinc organisms. oxygen consumption data arc prcscntcd as umo1.g" h ' on a dry wcight basis and havc bcen rccalculatcd from original data whcrc ncccssary. using mcasurcd values for % dry mass. results for benthic spccics arc from whitc (1975). ralph & maxwcll (1y77a. b ) . houlihan & allan (1982). luxmoorc (1984). and peck ct a l . (19r6). and for pelagic organisms from lkcda (1970). lkcda & hing fay (1981). lkcda & mitchcll (1982). hirchc (1983. 1y84). and rcinkc (1987). opcn symbols dcnotc hcrbivorcs and closcd symbols carnivorcs/omnivorcs. the data for gclatinous zooplankton arc shown as squarcs. all data was obtaincd hctwccn i .s"c and + 1.5"c. moditicd from an unpublished manuscript hv pcck & clarkc physiology of polar marine zooplankton 365 i n the energy requirements of benthic and plank tonic existence? since most measurements of oxy gen consumption and total energy flux have been made during summer, the difference may reflect in part a greater rate of tissue synthesis in plank ton compared with benthos (and the fast growth rates reported for some planktonic forms do not appear to be matched anywhere in the benthos). a more general explanation, in our view, is simply the cost of a planktonic existence. although some indirect arguments have indicated a low cost to swimming activity in plankton (or strictly, a low incremental cost to vertical migration over the cost of staying at the same level in the water column) recent direct measures (torres et al. 1982; torres & childress 1983; torres 1984) and theoretical analyses (morris et al. 1983) have indicated that the energetic cost of swimming in planktonic crustaceans is high, especially at low speeds (cowles et al. 1986). this preliminary analysis would thus suggest that there are two basic ways of making a living in the sea. one is to live on the seabed where costs are low but food can be sought essentially in only two dimensions. the other is to move into the water column where energetic costs are higher, but so are the rewards since food can be sought in three dimensions. few, if any, polar benthic species appear to grow fast. if the high summer growth rates of some zooplankton during the bloom are found to be a widespread phenom enon, this would emphasise further the dif ferences in both the costs of and the benefits from a planktonic existence. however a more detailed examination of the data suggests an important third category, namely gelatinous zooplankton. account for differences of the order of that found here between plankton and benthos ( ~ 6 ) . there is also the difficulty that the basis of the tissue mass calculation differs between groups. in par ticular, values quoted for benthic herbivores (mainly molluscs) are in terms of dry flesh mass excluding shell, whereas thosefor other groups (especially pelagic species) are on the basis of total dry mass. since any error included by ignor ing skeletal material in some benthos will have reduced the observed difference between benthic and pelagic species, these variations in math ematical treatment will not have affected the over all conclusion. overall energy flux the data in figs. 4 and 5 indicate that the meta bolic rates of planktonic species are significantly greater than those of benthic species (sometimes substantially so). since food for both groups of organism is presumably reduced to much the same extent in winter, it is not surprising that pelagic species should require a greater overwintering reserve. the ability of planktonic carnivores to continue energy intake over winter explains the slightly smaller size of their lipid reserves (as discussed above). however, it is interesting that the reverse pattern appears to be found in benthic species (although the overall size of lipid stores in benthos are smaller than in plankton). the reason for this is unknown, but the explanation may be associated with locomotor activity; most benthic herbivores analysed so far have been sess ile filter feeders whereas most carnivores/ omnivores were errant species. it is notoriously difficult to estimate the total energy flux through a free-living marine organism. most estimates for planktonic species are high, and for copepods in the production season some estimates have exceeded 100% body mass/day (see discussion in cushing 1975). euphausiids appear t o consume about 20% body mass/day (ross 1982; stuart 1986; clarke et al. 1988) and chaetognaths about 5-11% (0resland 1990). in contrast benthic invertebrate energy intake is usu ally of the order 1-5% (clarke 1990). these data are sparse and have been obtained with a variety of techniques and approaches. generally, how ever, they match the data for oxygen consumption i n indicating a greater energy requirement for plankton than benthos. what might explain this substantial difference the specialised energetic niche of gelatinous zooplankton in figs. 4 and 5 data for gelatinous zooplankton have been plotted separately from non-gelatinous species. there are peculiar difficulties in dealing with data for gelatinous species, particularly in that precise measures of either dry mass or organic content are technically difficult. these difficulties may mean that expression of oxygen consumption data on a dry mass basis (as here) may not be entirely valid because of the high level of mineral ash and the possible inclusion of some residual water in the dry mass value. 366 a . clarke & l . s . peck nevertheless, the data we do have for polar gelatinous species, including both herbivores (salps) and carnivores (ctenophores, medusae, siphonophores) suggest that these groups have a quite distinct energetic strategy. they have a relatively low oxygen consumption, which is pre sumably because the achievement of near neutral buoyancy has reduced the metabolic costs of a pelagic existence. direct measures of the cost of locomotion in gelatinous zooplankton have generally been low (trueman et al. 1984; larson 1987), although daniel (1985) reported a high cost in small hydromedusae. clearly, however. the costs of locomotion in gelatinous zooplankton cannot be high when oxygen uptake is low. gel atinous zooplankton also show no marked tend ency to store large amounts of lipid, and laboratory experiments have indicated a well developed ability to degrow during periods of food shortage (see for example. morris et al. 1983). many gelatinous zooplankton can grow and reproduce very fast when feeding conditions are suitable: salps. ctenophores. and medusae can all produce substantial populations rapidly. this indicates that peak energy throughput may be quite high. although this would be reflected in an increased respiration rate, the low locomotor costs of gelatinous species mean that total res piratory costs would still be relatively low in comparison with, for example, crustacean zoo plankton. direct measures are badly needed. although, as we have emphasised. the data can only admit of a somewhat speculative inter pretation we would propose that marine invert ebrates can be classified broadly into three categories on energetic terms: benthic low locomotor costs, with small lipid non-gelatinous pelagic high locomotor costs, gelatinous pelagic low locomotor costs, with stores; generally low energy throughput. with large lipid stores; high energy throughput. small lipid stores; variable energy throughput. the inclusion of nektonic species such as squid and fish. many of which have achieved near neu tral buoyancy through lipid stores or swimblad ders, would have introduced a fourth category into this classification. i t may be that gelatinous zooplankton have been able to combine the advantage of a lower oxygen consumption with at least some of the locomotory and dispersal mechanisms available to pelagic species. their feeding strategies d o not require significant burst activity and although they are fed upon by a variety of predators they have not developed energy-intensive modes of escape. they are nevertheless widespread in all seas of the world, and of enormous ecological importance (see, for example, harbison et al. 1978). these striking differences between the energetics of gelatinous and non-gelatinous species clearly need further investigation. acknowledgemenu. a . c . would like to thank c. c. e. hop kins of the university of tromso for the opportunity to under take comparative work in the arctic, and for the invitation to participate in the pro mare symposium. the british antarctic survey is a component body of the natural environment research council. we thank a . atkinson for permission to use some of his unpublished data. and we thank the referees for helpful and perceptive criticism of an early draft of this paper. references andrcws. k . j . h. 1966: the distribution and life history of calanordes acutus (gieshrecht). 'discovery' rep. 34, 117 162. atkinson. a . 1989: distribution of six major copepod species around south georgia in early summer. polar biol. 9. 35% 363 atkinson. a . 1991: life cycles of calunoides ucutus. culunus simillrmus and rhincalanus gigas (copepoda: calanoida) within the scotia sea. marine biol. 109. 79-91. baker. a . de c . 1959: distribution and life history of euphausiu rriocanrha. halt and tattersall. 'discooery' rep. 29.30%340. bimstedt. u . 1976: studies on the deep-water pelagic com munity of korsfjorden. western norway. changes in the size and hiochemical composition of megunvctiphanes noroegica (euphausiacea) i n relation to its life-cycle. sursia 61, 15-30. bimstedt. u. 1980: biochemical components as indicators o f seasonal condition of deep-water zooplankton. pp. 447-451 in freeland. h. j . & levings, c. d. (eds.): fjord oceanographv: proceedings of the n a t o conference on fjord ocean ograpliy. victoria. b . c . . cunadu. june 48, 1979. n a t o conference series v1. murine sciencer vol. 4. plenum press. new york. bamstedt. u . 19x6: chemical composition and encrgy content. pp. 1-58 in corner. e. d. s . & o'hara. s. c. m . (eds.): the biologrcal chemistry of marine copepods. clarendon prcss. oxford. carey. a. g . 1985: marine ice fauna. pp. 173-190 in horner, r. a . (ed.): sea ice biota. c r c press. boca raton. childrcss. j . j . 1977: physiological approaches to the biology of midwater organisms. pp. 301-324 in andersen. n . r . & zahurancc. b. j . (eds.): oceunic sound scumring predicrion. plenum press. new york. chojnacki. j . & wcglenska. t. 1984: pcriodocity o f compo sition. abundance. and vertical distribution of summer zooplankton (1977/78) in ezcurra inlct. admiralty bay (king george island. south shetland). 1. plunktun res. 6, 977 1017 physiology of polar marine zooplankton 367 environmental factors. j . exp. mar. biol. ecol. 49, 103-120. falk-petersen, s., sargent, j . r . . hopkins. c. c. e. & vaja. b. 1982: ecological investigations on the zooplankton com munity of balsfjorden, northern norway: lipids in the euphausiids thysanoessa raschii and t . inermis during spring. mar. biol. 68. 97-102. foxton, p. 1966: the distribution and life-history of salpa thompsoni foxton with observations on a related species, salpa gerlachei foxton. ‘discovery’ rep. 34, 1-116. gatten, r. r., sargent, j. r., forsberg, t . e. v.. o h a r a . s. c. m. & corner, e . d. s. 1980: on the nutrition and metab olism of zooplankton. xiv. utilization of lipid by calanus helgolandicus during maturation and reproduction. j. mar. biol. ass. u.k. 60, 391-399. gliwicz, z. m. 1990: food thresholds and body size in cla docerans. nature 343, 6 3 w o . hagen, w. 1988: zur bedeutung der lipide im antarktischen zooplankton. ber. polarforsch. 49, 1-129. harbison, g . r., maddin, l. p. & swanberg, n. r. 1978: on the natural history and distribution of oceanic ctenophores. deep-sea res. 25, 233-256. hirche, h . 4 . 1983: excretion and respiration of the antarctic krill euphausia superba. polar biol. 1,205-209. hirche, h . 4 . 1984: temperature and metabolism of plankton i. respiration of antarctic zooplankton at different tem peratures with a comparison of antarctic and nordic krill. comp. biochem. physiol. 77a. 367-368. hirche, h.-j. 1989: egg production of the arctic copepod calanus glacialis: laboratory experiments. mar. biol. 103, 311-318. hirche, h.-j. 1990: egg production of calanusfinmarchicus at low temperature. mar. biol. 106. 53-58. holm-hansen, 0.. mitchell, b. g., hewes, c. d. & karl. d. m. 1989: phytoplankton blooms in the vicinity of palmer station, antarctica. polar biol. 10. 49-57. hopkins, c. c. e.. tande, k. s., g r ~ n v i k , s . & sargent, j. r. 1984: ecological investigations of the zooplankton com munity of balsfjorden, northern norway: an analysis of growth and overwintering tactics in relation to niche and environment in metridia longa (lubbock), calanus fin mq’chicus (gunnerus), thysanoessa inermis ( k r ~ y e r ) and t. raschii ( m . s a a ) . j . exp. mar. biol. ecol. 82, 77-99. houlihan, d . f. & allan, d . 1982: oxygen consumption of some antarctic and british gastropods: an evaluation of cold adaptation. comp. biochem. physiol. 73a. 383-387. huntley, m. & escritor. f. 1991: dynamicsof calanoides acutus (copepoda: calanoida) in antarctic coastal waters. deep sea res. in press. ikeda. t. 1970: relationship between respiration rate and body size in marine plankton animals as a function of the tem perature of habitat. bull. far. fish.. hokkaido univ. 21. 19 112. ikeda, t. 1974: nutritional ecology of marine zooplankton. mem. fac. fish., hokkaido univ. 22. 1-97. ikeda, t. 1985: metabolic rates of epipelagic marine zooplank ton as a function of body mass and temperature. mar. biol. ikeda. t. & dixon, p. 1982: body-shrinkage: a possible over wintering strategy of the antarctic krill (euphausia superba dana). j . exp. mar. biol. ecol. 62. 143-157. lkeda, t. & hing fay, e. 1981: metabolic activity of zooplank ton from the antarctic ocean. aust. j. mar. freshw. res. 32, 921-930. ikeda. t. & mitchell, a . w. 1982: oxygen uptake, ammonia excretion and phosphate excretion by krill and other ant 85, 1-11. clarke, a . 1977: seasonal variations in the total lipid content of chorismus antarcticus (pfeffer) (crustacea: decapoda) from south georgia. j . exp. mar. biol. ecol. 27, 93-106. clarke, a. 1983: life in cold water: the physiological ecology of polar marine ectotherms. oceanogr. mar. biol. ann. rev. clarke, a . 1984a: the lipid content and composition of some antarctic macrozooplankton. bull. br. antarct. surv. 63,57 70. clarke. a. 1984b: lipid composition of two species of serolis (crustacea, isopoda) from antarctica. bull. br. antarct. surv. 64. 37-53. clarke, a . 1987a: the adaptation of aquatic animals to low temperatures. pp. 315-338 in grout, b. w. w. & morris, g. j . (eds.): the effects of low temperature on biologicalsystem. edward arnold, london. clarke. a . 1987b: temperature. latitude and reproductive effort. mar. ecol. progr. ser. 38, 89-99. clarke, a. 1988: seasonality in the antarctic marine environ ment. comp. biochem. physiol. 908. 461-473. clarke, a. 1990: faecal egestion and ammonia excretion in the antarctic limpet nacella concinna (strebel, 1908). j . exp. mar. biol. ecol. 138, 227-246. clarke. a. 1991: what is cold adaptation and how should we measure it? a m . zool. 31. in press. clarke, a . & crame. j . a . 1989: the origin of the southern ocean marine fauna. pp. 253-268 in crame. j . a. (ed.): origins and evolution of the antarctic biota. geological society special publication no. 47, geological society. london. clarke, a. & north, a . w. 1991: is the growth of polar fish limited by temperature? in di prisco, g., maresca. b. & tota. b. (eds.) biology of antarctic fishes. proceedings of the second international conference, raoello, italy, 30 may i june 1990. springer verlag, berlin. in press. clarke, a., quetin, l. b. & ross, r. m. 1988: laboratory and field estimates of the rate of faecal pellet production by antarctic krill, euphausia superba. mar. biol. 98. 557 563. clarke, a , , ellis-evans, j . c., sanders, m. w. & holmes, l. j. 1989: patterns of energy storage in pseudoboekella poppei (crustacea, copepoda) from two contrasting lakes on signy island. antarctica. (developments in hydrobiology 49) hydrobiologia 172, 183-191. cowles. d. l., childress, j . j. & gluck, d. l. 1986: new method reveals unexpected relationship between velocity and drag in the bathypelagic mysid gnathophausia ingens. deep sea res. 33, 865-880. cushing. d. h . 1975: marine ecology andfisheries. cambridge university press. 278 pp. daly, k. l. & macaulay, m. c. 1988: abundance and dis tribution of krill in the ice-edge zone of the weddell sea, austral spring 1983. deep-sea res. 35, 21-41. daniel. t. s. 1985: cost of locomotion: unsteady medusa swim ming. j. exp. biol. 119, 149-164. david, p. m. 1955: the distribution of sagitta gazellae ritter zahoney. ‘discovery’ rep. 27, 235-278. ettershank. g. 1983: age structure and cyclical annual size change in the antarctic krill, euphausia superba dana. polar biol. 2. 189-193. falk-petersen. s. 1981: ecological investigations on the zooplankton community of balsfjorden. northern norway: seasonal changes in body weight and the main biochemical composition of thysanoessa inermis ( k r ~ y e r ) , t. raschii (m. sars) and meganyctiphanes norvegica (m. sars) in relation to 21,341-453. 368 a . clarke & l . s. peck arctic zooplankton i n relation to their body size and chemical composition. mar. biol. 71. 28%298. ivleva. i . v . 1980: the dependence of crustacean respiration on body mass and habitat temperature. 1nf. reu. ges. hydrobiol. 6 5 . 1-47. kane. j . e . 1966: the distribution of parafhemisro gaudirhaudri (guer). with observations on its life-history i n the 0" to 20" sector of the southern ocean. 'discotier!' rep. 34. 163 198. larson. r . j . 1987: costs of transport for the seyphomedusan stomolophus meleagris l agassiz. can. 1. 2001. 6 5 . 2 6 w 2695 l a n o n , r. j . & harbison. g . r. 1989: sourcc and fate of lipids in polar gelatinous zooplankton. arctic 42. 339-346. lawrence. j . m. & guille. a . 1982: organic composition of tropical, polar and temperate-water echinoderms. comp. biochem. physiol. 7 2 8 . 283-298. lee. r . f. 1974: lipid composition of the copepod calanus hyperboreus from the arctic ocean. changes with depth and season. mar. b i d . 2 6 . 31s318. lee, r . f. 1975: lipidsof arcticzooplankton. c o m p . biochem. physiol. 51b. 263-266. lee. r . f. & hirota. j . 1973 wax ester in tropical zooplankton and nekton and the geographical distribution of wax esters in marine copepods. limnol. oreanogr. 18. 227-239. littlepage, j. l. 1964: seasonal variation i n lipid content of two antarctic marine crustacea. pp. 465-470 in carrick. r . , holdgate, m. w. & prevost. j . (eds.): biologie anrarctique. actualites scientifiques et industrielles. 1312. hermann. paris. littlepage, j . l . 1965: oceanographic investigations in mcmurdo sound. pp. 1-37 in llano. g . a . (ed.): biology of anfarcrir seas v . american geophysical union. washington. d . c. anfarcric research series 5 . lonsdale. d. j . & levinton. j . s. 1986: growth rate and reproductive differences in a widespread estuarinc har pacticoid copepod (scortolana canademis). mar. biol. 91. 231-237. luxmoore. r. a . 1984: a comparison of the respiration rates of some antarctic isopods with species from lower latitudes. bull. br. anfarcr. surii. 62. 5 m 5 . marschall. h.-p. 1988: the overwintering strategy of antarctic krill under the pack-ice of the weddell sea. polar biol. 9 . 129-135. matthews. j. b. l . 1968: on the acclimatization of calanus finmarchicus (crustacca. copepoda) to different temperature conditions i n the north atlantic. sarsia 34. 371-382. morris, m. j . . gust. g . & torres. j. j . 1985: propulsion efficiency and cost of transport for copepods: a hydro mechanical model of crustacean swimming. mar. biol. 8 6 . 28s295 morris. r . j . 19x3: absence of wax esters in pelagic lake baikal fauna. lipids 18. 14y-150 morris. r . j . 1984: the endemic fauna of lake baikal: their general biochemistry and detailed lipid composition. proc. r. soc lond. b 222. 51-78. morris. r . j . . mccartney. m. j . & schulze-robbecke. a . 1983: bolinopsis infundrhulurn (0. f. muller): biochemical composition in relation to diet. j. exp. mar. b i d . ecol. 67. 149-157. norrbin. f. & bimstedt. u 1984: energy contents in benthic and planktonic invertebrates of kosterfjorden. sweden. a comparison of energetic strategies i n marine organism groups. ophelia 2 3 . 47-64. 0rcsland. v . 1990: feeding and predation impact on the chae tognath eukrohnia hamafa in gerlache strait. antarctic pen insula. mar. ecol. progr. ser. 6 3 . 201-209. parkinson. c . l.. comiso. j . c . . zwally, h . j . , cavalieri, d. j.. gloerscn. p. & campbell. w. j . 1987: arcfic sea ice 1973 1976: safellire passive-microwaoe observations. nasa sp 489, nasa. washington d.c. 296 pp. peck. l. s.. morris. d. j . , clarke, a . & holmes, l. j . 1986: oxygen consumption and nitrogen excretion in the antarctic brachiopod liorhyrella uua (jackson. 1912) under simulated winter conditions. j . exp. mar. biol. ecol. 104, 203-213. percy, j . a. 1979: seasonal changes in organic composition and caloric content of an arctic marine amphipod onisifnus (=boeckosimus) afinis h . j . hansen. j . exp. mar. biol. ecol. 40. 183-192. percy, j. a . & fife, f. j . 1981: the biochemical composition and energy content of arctic marine macrozooplankton. arr fir 3 4 , 307-313. priddle. j . . hawes, i . & ellis-evans. j . c . 1986: antarctic aquatic ecosystems as habitats for phytoplankton. biol rev. 6 1 , 199-238. ralph. r . & maxwell. j. h . g . 1977a: the oxygen consumption of the antarctic limpet nacella (patinigera) concinna. bull. br. antarrf. suru. 45. iy-23. ralph, r . & maxwell. j . g . 1977b: the oxygen consumption of the antarctic lamellibranch gaimardia rrapesina rrapesina in relation to cold adaptation in polar invertebratcs. bull. br. anfarct. suru. 45. 4146. reinke. m. 1987: zur nahrungsund bewegungsphysiologie von salpa thompsoni und salpa jusiformis. ber. polarforsch. 36. 1-89. ross. r. m. 1982: energetics of euphausia pacifica. i . effects of b o d y carbon and nitrogen and temperature on measured and predicted production. mar. biol. 6 2 , 131-137. ross. r. m.. quetin. l. b. & kirsch, e . 1988: effect of temperature on development times and survival of early larval stages of euphausia superba dana. j . exp. mar. biol. ecol. 121. 5571. sargent. j. r . & falk-petersen, s. 1981: ecological inves tigations on the zooplankton community of balsfjorden. northern norway: lipids and fatty acids in meganvcriphanes noroegica. thysanoessa rmchii and thysanoessa inermis dur ing midwinter. mar. biol. 6 2 , 131-137. siegel. v. 1987: age and growth of antarctic euphausiacea (crustacea) under natural conditions. mar. biol. 96. 483 495. smetacek, v.. scharek, r. & nothig, e.-m. 1990: seasonal and regional variation in the pelagial and its relationship to the life history cycle of krill. pp. 103-114 i n kerry, k. r. & hempel. g. (eds.): antarctic ecosysfems. ecological change and comeroafion. springer verlag. berlin. stuart. v. 1986: feeding and metabolism of euphausia lucens (euphausiacea) in the southern benguela current. mar. ecol. progr. ser. 30. 117-125. sullivan. c . w.. mcclain, c . r . . comiso. j . c . & smith. w . 0. 1988: phytoplankton standing crops within an antarctic ice edge assessed by satellite remote sensing. j. geophvr. res. 93 cio. 12487-12498. tande. k., hassel. a . & slagstad, d. 1985: gonad maturation and possible life-cycle strategies in calanusfinmarchicus and calanus glacialis in the northern barents sea. pp. 141-155 in gray, j. s. & christiansen. m. w. (eds.): marine biology of polar regions and effects of stress on marine organims. j . wiley and sons, chichester. torres. j . j . 1984: relationship of oxygen consumption to swimming speed in euphausia pacifica. 11. drag. efficiency and a comparison with other swimming organisms. mar. biol. 78, 231-237. torres, j . j . & childress, j . j. 1983: relationship of oxygen consumption to swimming speed in euphausia pacifica. 1. effects of temperature and pressure. mar. biol. 74. 79-86. torres, j . j., childress, j . j . & quetin, l. b. 1982: a pressure vessel for the simultaneous determination of oxygcn con sumption and swimming speed in zooplankton. deep-sea res. 29. 63 1-639, trueman. e. r . , bone. 0. & bracconot. j . c. 1984: oxygen consumption in swimming salps (tunicata: thaliacea). j . exp. biol. 110. 323-327. voronina. n. m., vladimirskaya, ye. v. & zmiyevskaya. m. i. 1978: seasonal variations in the age composition and vertical distribution of common zooplankton species in the southern ocean. oceanology, wash. (english trawl.) 18. 335-338. voronina, n. m.. menshutkin, v. v. & tseytlin. v. b. 1980: production of the common species of antarctic copepod, physiology of polar marine zooplankton 369 calanoides acutus. oceanology, wash. (english rransl.) 20. 90-93. wacasey, j . w. & atkinson, e. g . 1987: energy values of marine benthic invertebrates from the canadian arctic. mar. ecol. progr. ser. 39, 243-250. ward, p. 1984: aspects of the biology of anfarctomysis maxima (crustacea: mysidacea). polar biol. 3 , 85-92. white, m. g . 1975: oxygen consumption and nitrogen excretion by the giant antarctic isopod glyptonotus ant arcticus eights in relation to cold adapted metabolism in marine polar poikilotherms. pp. 707-724 in barnes. h. (ed.): proc. 9th europ. mar. biol. symp. aberdeen university press. zwally, h. i., comiso, j . c., parkinson. c. l . . campbell. w. j., carsey, f. p. & gloersen. p. 1983: anrarcfrcsea ice. 1973 1976: satellite passive-microwave obseruatiow. nasa sp 459. nasa, washington, d.c. 206 pp. doi:10.3402/polar.v33.22103 r e s e a r c h / r e v i e w a r t i c l e alien invasions in antarctica*is anyone liable? kevin a. hughes & peter convey british antarctic survey, natural environment research council, high cross, madingley road, cambridge cb30et, uk keywords liability annex; non-native species; environmental protocol; antarctic treaty area; eradication; environmental emergency. correspondence kevin a. hughes, british antarctic survey, natural environment research council, high cross, madingley road, cambridge cb30et, uk. e-mail: kehu@bas.ac.uk abstract the introduction of non-native species to antarctica in association with human activities is a major threat to indigenous biodiversity and the region’s unique ecosystems, as has been well-demonstrated in other ecosystems globally. existing legislation contained in the protocol on environmental protection to the antarctic treaty does not specifically make the eradication of non-native species mandatory, although it is implicit that human-assisted introductions should not take place. furthermore, to date, eradications of non-native species in the treaty area have been infrequent and slow to progress. in 2005 an additional annex (vi) to the protocol was agreed concerning ‘‘liability arising from environmental emergencies.’’ this annex focusses on prevention of environmental emergencies, contingency planning and reclaiming costs incurred when responding to an environmental emergency caused by another operator within the antarctic treaty area. however, the types of environmental emergencies covered by the annex are not defined. in this paper we highlight potential difficulties with the application of annex vi in the context of non-native species control and eradication, including, for example, whether a non-native species introduction would be classified as an ‘‘environmental emergency’’ and therefore be considered under the terms of the annex. even if this were the case, we conclude that the slow pace of approval of the annex by antarctic treaty parties may prevent it coming into force for many years and, once in force, in its current form it is unlikely to be useful for reclaiming costs associated with the eradication or management of a non-native species. antarctica is the most pristine continent remaining on the planet, yet is under pressure from environmental impacts originating both from within and outside the region (bargagli 2005; tin et al. 2009; aronson et al. 2011; tin et al. 2013). in particular, the introduction of invasive non-native species could present a major threat to the continent’s indigenous biodiversity, and it is essential that steps are taken to control and, if possible, eradicate any introduced species as soon as possible after their discovery (chown, huiskes et al. 2012; chown, lee et al. 2012; hughes, huiskes et al. 2013). in this paper we aim to (1) detail the international instruments currently in force within the antarctic treaty system relating to nonnative species and (2) examine the potential applicability of annex vi (‘‘liability arising from environmental emergencies’’) to the protocol on environmental protection to the antarctic treaty (also known as the environmental protocol or madrid protocol), for parties operating in the region with regard to non-native species introductions. antarctic ecosystems only 0.34% of the antarctic continent is ice-free and it is within this area of ca. 44 000 km 2 that antarctica’s unique terrestrial biological communities are found. antarctic terrestrial systems are characterized by a low biodiversity (convey 2013). trees and most higher plants are absent from the continent, and the generally sparse vegetation is dominated by mosses and liverworts, with flowering plants represented by only two species, the grass to access the supplementary material for this article, please see supplementary files under article tools online. polar research 2014. # 2014 kevin a. hughes & peter convey. this is an open access article distributed under the terms of the creative commons attributionnoncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/22103/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/22103/0 http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 deschampsia antarctica and the cushion plant colobanthus quitensis. all vertebrate animals in antarctica (e.g., seals, marine bird species) rely on the marine environment for food and true terrestrial animals are limited to two species of dipteran and acari (mites), collembola (springtails), tardigrada (waterbears), nematoda, rotifera and protozoans. microbial communities dominate in antarctica. as environmental conditions become increasingly severe, generally with distance from the coast or altitude, biodiversity becomes limited to microorganisms (algae, bacteria, cyanobacteria, viruses and protozoa) found within the poorly developed soils, and fissures and voids in rocks and other locations where liquid water may be present (vincent 1988; wynn-williams 1996; hughes & lawley 2003). lichens (a microbial symbiosis of fungal and algal species) are found throughout antarctica, with different species occupying all but the most extreme terrestrial habitats. recent research has led to the realization that there is distinct regionalization in antarctic terrestrial biodiversity (convey & stevens 2007; convey et al. 2008), often of ancient origin. fifteen different antarctic conservation biogeographic regions have been identified, each containing a substantially different combination of cosmopolitan and local endemic species (terauds et al. 2012). while antarctica’s terrestrial fauna and flora are typically cryptic and lack the ‘‘charismatic’’ elements more familiar from temperate and tropical regions, the spatial area of habitat is small compared to the size of the continent, and designation of protected areas is of critical importance. in contrast with terrestrial ecosystems, antarctica’s marine environments are much more biodiverse. benthic habitats, in particular, may possess biodiversity and biomass equivalent to some of the richest locations found globally, second only to tropical coral reefs (clarke & johnston 2003). marine habitats experience chronically low but stable sea water temperatures, that are rarely beyond a few degrees either side of 08c (peck et al. 2006). high levels of marine primary productivity during the austral summer, in the form of algal blooms, provide a food source for pelagic marine invertebrate species such as krill and salps that in turn support fish and higher predators including penguins, whales, seals and flying bird species. non-native species introductions global human impacts apparent in antarctica include climate change, ocean acidification, ozone depletion and ocean and atmospheric pollution dispersed over long distances, while local impacts include the historic overexploitation of living marine resources, pollution, degradation of habitat and disturbance of wildlife (for reviews see bargagli 2005; tin et al. 2009; aronson et al. 2011; convey et al. 2012). the amount and extent of human activity within the antarctic treaty area (formally defined as the area south of latitude 608s) has increased in recent decades, both with a rise in the amount of ship and landbased tourism, and with the construction of new national governmental operator research stations in previously unimpacted locations and expansion of their operational footprints (hughes, fretwell et al. 2011; convey et al. 2012). in the recent past, tourism peaked in the 2007/08 austral summer with over 37 000 tourist landings, predominantly within the antarctic peninsula region, but the numbers then contracted slightly, associated with the global economic downturn (iaato 2013). nevertheless, the decline has stabilized and numbers are likely to return to their previous upward trend. national operators currently have over 75 research stations that may be occupied year-round or during the austral summer season, plus numerous refuges, huts and temporary field camps (comnap 2013a). over 4000 scientists and support staff may be present in antarctica during the summer, with populations falling to ca. 1000 during the winter. in recent decades, environmental emergencies within the antarctic treaty area have been associated mainly with the activities of national operators, although incidents involving tourist vessels have occurred, such as the sinking of ms explorer in 2007 (chile 2008; aronson et al. 2011). the most significant environmental incident in the modern era in antarctica was the sinking of the argentinian supply vessel bahia paraiso in 1989, which released 600 000 litres of petroleum (kennicutt et al. 1991; kennicutt & sweet 1992). in the same year 260 000 litres of fuel were spilled on williams field on the ross ice shelf, 13 km from mcmurdo station (wilkness 1990). added to pollution incidents, the unintentional introduction of non-native species is potentially a major threat to indigenous antarctic biodiversity. due to the spatial distribution of human visitation and climate change impacts, some regions*the northern antarctic peninsula and its offshore islands, in particular*may be more at risk than others (frenot et al. 2005; convey 2008; hughes & convey 2010; cowan et al. 2011; chown, huiskes et al. 2012; chown, lee et al. 2012). once non-native species are introduced, they may become established and, in some cases, become invasive through expansion of their distribution and displacement of indigenous biodiversity. non-native species can be introduced inadvertently to antarctic terrestrial environments associated with imported cargo, vehicles, fresh foods, scientific equipment and personal clothing and effects (lee & chown 2009a, 2009b; hughes et al. 2010; hughes, lee et al. 2011; alien invasions in antarctica k.a. hughes & p. convey 2 (page number not for citation purpose) citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 chown, huiskes et al. 2012; tsujimoto & imura 2012). although less well characterized and apparently infrequent within antarctica, introductions to marine environments may occur through transport on ship hulls or in ballast water (lewis et al. 2003; lewis et al. 2006; united kingdom 2006; lee & chown 2007). antarctica currently hosts very few non-native species compared to other areas of the earth (e.g., corte 1961; olech 1996; hughes & worland 2010; greenslade et al. 2012; molinamontenegro et al. 2012), but the increasing magnitude and distribution of human activity in the region is expected to increase the likelihood of non-native species introductions (frenot et al. 2005; hughes, huiskes et al. 2014; chown, huiskes et al. 2012; chown, lee et al. 2012). furthermore, climate change, particularly over the antarctic peninsula region but also over continental antarctica, may increase the risk of species establishment and subsequent invasion (convey et al. 2009; steig et al. 2009; turner et al. 2009; convey 2011; chown, huiskes et al. 2012). native antarctic terrestrial communities typically have low diversity and are thought to have low functional redundancy as well as containing ‘‘empty’’ niches (convey 2013). their long history of evolutionary isolation is evidenced by high levels of endemism across most component groups of biota (convey et al. 2008; pugh & convey 2008), while the severe environmental conditions have resulted in the predominance of ‘‘adversity selected’’ life history characteristics, a feature of which is poor competitive ability and vulnerability to invasion by more effective competitors (kennedy 1993; convey 1996). as a result, identifying methods to reduce the likelihood of alien species introductions has been a focus of the committee for environmental protection (cep) at the antarctic treaty consultative meetings (atcms) over recent years. legislation concerning non-native species* precedents from outside antarctica outside the antarctic treaty area, national legislation and regional and international instruments exist concerning the introduction and/or control of non-native species (shine et al. 2000; fasham & trumper 2001; miller et al. 2006). in some cases national legislation may have been developed in response to the convention on biological diversity (cbd), which was signed in 1992 and entered into force in 1993, and which requires its 193 parties to ‘‘prevent the introduction of, control and eradicate alien species, which threaten local or regional biodiversity.’’ (the cbd applies formally only to sovereign territory and as national territorial claims within antarctica are placed in abeyance under the antarctic treaty, the cbd itself does not apply to antarctica despite the majority of antarctic treaty parties also being cbd signatory nations.) however, in some cases, domestic legislation may not be integrated into a coherent framework, making it difficult to enforce and therefore largely ineffective (manchester & bullock 2000; miller et al. 2006; hulme et al. 2008). furthermore, domestic legislation may not make it an explicit requirement that non-native species are controlled or eradicated for reasons of ecological or environmental conservation and protection (fasham & trumer 2001). few nations have domestic legislation whereby costs resulting from the introduction and/or eradication of a non-native species can be reclaimed from those who were responsible for the introduction. however, new zealand was one of the first nations to develop an integrated framework for identifying non-native species and managing the associated risks across all sectors, which came into effect through the biosecurity act (1993; available at http://legislation.govt.nz/act/public/1993/ 0095/ latest/ dlm314623.html). the act’s pest management strategy determines how a non-native species is to be controlled or eradicated and sets out how this should be funded, with the aim of sharing cost fairly between those responsible for the introduction and those who would benefit from the species eradication or control (fasham & trumper 2001). globally, many governments have been slow to enact effective biosecurity legislation, particularly as human activity over many centuries or millennia has already introduced many hundreds or thousands of non-native species to some countries. in contrast, antarctica has had only a brief period of human occupation and non-native species are still few compared to other parts of the earth, making the development of an integrated framework for non-native species management for the continent both important and achievable. antarctic governance and legal instruments the antarctic treaty has been signed by 50 parties (nations), whose populations constitute approximately 65% of the world’s population. twenty-nine parties are consultative parties, including the original 12 treaty signatory parties and a further 17 parties that have acceded to the treaty by demonstrating their interest in antarctica by conducting substantial research activity there (as set out in article 9[2]). the 21 non-consultative parties are invited to attend the atcms, but only consultative parties are entitled to participate in decision making, which must be by consensus. within the antarctic treaty system, for an international instrument to come into effect it must be approved by all the parties that had consultative status when the k.a. hughes & p. convey alien invasions in antarctica citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 3 (page number not for citation purpose) http://legislation.govt.nz/act/public/1993/0095/latest/dlm314623.html http://legislation.govt.nz/act/public/1993/0095/latest/dlm314623.html http://legislation.govt.nz/act/public/1993/0095/latest/dlm314623.html http://legislation.govt.nz/act/public/1993/0095/latest/dlm314623.html http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 instrument was adopted originally. as a result, it can take many years for international instruments to come into effect. for example, the environmental protocol was signed on 4 october 1991, but did not enter into force until approved by each party (using their own definition of what this entails) on 14 january 1998. the environmental protocol the environmental protocol is the main legal instrument concerned with the protection of the antarctic environment within the antarctic treaty area. the protocol has been approved by all 29 consultative parties to the antarctic treaty but, of the 21 non-consultative parties, it has been approved by only six. further, the environmental protocol does not apply to nations that are not signatories to the antarctic treaty. the environmental protocol has five annexes currently in effect, which set out minimum environmental standards concerning environmental impact assessment (annex i), conservation of antarctic fauna and flora (annex ii), waste disposal (annex iii), prevention of marine pollution (annex iv) and the protected area system (annex v). in subsequent sections we highlight text within the environmental protocol that is of relevance to non-native species introductions and describe annex vi*‘‘liability arising from environmental emergencies,’’ which has yet to enter into force. we then go on to discuss issues that may deserve more consideration when applying this new international instrument to non-native species introductions. annex i: environmental impact assessment. the activities of all signatory nations within the antarctic treaty area, including tourism and national operator activities, must be formally permitted by the appropriate national authority and have undergone an environmental impact assessment in accordance with annex i of the environmental protocol. the level of environmental impact assessment undertaken for any activity in antarctic depends upon whether the activity is likely to result in an impact that is less, equivalent to, or greater than ‘‘minor or transitory.’’ annex i does not mention nonnative species introductions specifically; however, over time, an introduced species may cause environmental impact that is at least, if not substantially greater than, ‘‘minor’’ and/or longer lasting than ‘‘transitory,’’ and these potential consequences should be recognized during the environmental impact assessment process, as recommended in the ‘‘guidelines for environmental impact in antarctica’’ (available at http://ats.aq/documents/recatt/ att266_e.pdf). annex ii: conservation of fauna and flora. annex ii prohibits the intentional introduction of non-indigenous plants and animals to land, ice shelves or into water within the antarctic treaty area unless for a defined scientific purpose and in accordance with a permit (annex ii, article 4). furthermore, measure 16 (2009), which amends annex ii, prohibits the intentional introduction of all species of living organisms not native to the antarctic treaty area. little attention is given to the issue of unintentional or accidental introduction of nonnative species. article 4(6) states that parties should take precautions to prevent the introduction of microorganisms not present in the native flora and fauna. these precautions include checking that poultry imported for food is free of disease and is disposed of in a manner that eliminates risk to native flora and fauna, and that importation of non-sterile soil is avoided to the maximum extent possible. the environmental protocol makes no explicit mention of the transfer of native organisms from one antarctic region to another, although it does state that activities shall be limited to ensure that ‘‘the diversity of species, as well as the habitats essential to their existence, and the balance of the ecological systems existing within the antarctic treaty area are maintained’’ (annex ii, article 3[3c]). in other words, in relation to their activities, parties should take steps to reduce to a minimum the risks to the antarctic environment, including those associated with the introduction of non-native species, and ensure that ecosystems are maintained in their natural state. annex iv: prevention of marine pollution. annex iv establishes provisions to prevent marine pollution within the antarctic treaty area but does not mention non-native species specifically. however, it does state that sewage (and associated non-native microorganisms) and food waste must not be released within 12 nautical miles of the nearest land or ice shelf. annex v: area protection and management. annex v sets out the protected area system for antarctica but does not address non-native species specifically; however, designated protected areas must be accompanied by a management plan that may contain biosecurity measures intended to protect the values for which the area was designated (hughes & convey 2010). to assist those preparing management plans, the issue of nonnative species is mentioned in the ‘‘guide to the preparation of management plans for antarctic specially protected areas’’ (section 7[vi]; available at http://ats.aq/ documents/recatt/att477_e.pdf). alien invasions in antarctica k.a. hughes & p. convey 4 (page number not for citation purpose) citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 http://ats.aq/documents/recatt/att266_e.pdf). http://ats.aq/documents/recatt/att266_e.pdf). http://ats.aq/documents/recatt/att266_e.pdf). http://ats.aq/documents/recatt/att477_e.pdf http://ats.aq/documents/recatt/att477_e.pdf http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 annex vi: liability arising from environmental emergencies. at the 28th atcm a further annex to the environmental protocol was agreed. this was annex vi* ‘‘liability arising from environmental emergencies,’’ also known as the liability annex (available at http://www. ats.aq/e/ep.htm; see also supplementary file). annex vi has not yet come in to force, as it has not been approved by all consultative parties, and therefore has not been tested in any court. in contrast to other liability instruments, the scope of the liability annex is very limited, specifically to the costs of emergency response. the liability annex applies to environmental emergencies in the antarctic treaty area which relate to scientific research programmes, tourism and all other governmental and non-governmental activities (vöneky 2008). the preamble of the annex recalls the ‘‘importance of preventing, minimising and containing the impact of environmental emergencies.’’ the primary aim of the liability annex is to act as a deterrent for those who operate irresponsibly in antarctica, and it imposes financial liability on operators which fail to take response action, effectively establishing a ‘‘polluter pays’’ principle. once the annex becomes effective, in theory it will be possible to recoup costs incurred from the clean-up or remediation of pollution or environmental damage resulting from environmental emergencies caused by the actions of other signatory nations or their non-state operators within the antarctic treaty area. however, the range of environmental emergencies covered by the annex is not listed specifically, although later reference to ships suggests that those who drafted the text envisaged the annex to encompass marine incidents, including oil spills, and terrestrial pollution events. non-native species and the liability annex why are the annexes currently in force insufficient to deal with non-native species issues? crucially, measures for reinstatement of the damaged environment are not included specifically in the annexes currently in force (annexes i�v). moreover, control and/or eradication of non-native species is not a specified mandatory requirement under annex ii, although recommended in non-mandatory guidelines contained within the cep non-native species manual (cep 2011; adopted by the atcm through resolution 6 [2011]). as noted earlier, annex ii does contain a requirement that parties maintain antarctic species diversity, habitats and ecological systems (article 3[3c]), but this is limited in its effectiveness. to conform with article 3(3c), parties should prevent unintentional non-native species introductions and, if necessary, take management action to control or eradicate any species that have been introduced. however, this is not stated explicitly and examination of past examples of response action following the discovery of a nonnative species indicates that often little, or no, practical action is taken (smith 1996; hughes & worland 2010; united kingdom 2013). for example, the non-native grass poa pratensis has not been removed from the vicinity of the argentinian primavera station at cierva point on the antarctic peninsula following its introduction in 1954/55, although discussions on eradication have been initiated (corte 1961; pertierra et al. 2013), and neither has poa annua in the vicinity of arctowski station, king george island, south shetland islands (olech 1996; olech & chwedorzewska 2011). in contrast, the liability annex is much more explicit, with article 5 stating specifically that response action by an operator that has caused an environmental emergency should be prompt and effective. the implementation and enforcement of the requirements contained in the annexes currently in force is controlled fully by each individual party. despite legal obligations, parties may, or may not, be inclined to take action to enforce the legislation. for example, annex ii largely does not permit intentional non-native species introductions, but some parties do not enforce this requirement and non-native decorative plants are visible on some research stations (see figure 5.2 in hughes, huiskes et al. 2014). in contrast, should a liability instrument be in force that was considered applicable to the issue of nonnative species, then parties may have an incentive to make non-native species control and eradication a priority issue, particularly if they consider it possible that a second party might become involved and then attempt to claim back any costs. application of the liability annex to environmental emergencies involving non-native species the risks and consequences of a non-native species introduction, as an ‘‘environmental emergency,’’ may not have been considered in any depth (if at all) by the legal and policy groups during the greater part of negotiations of annex vi (aust & shears 1996). the issue of the unintentional introduction of macroscopic non-native species became a major priority for the cep only from 2004 onward (australia 2004, 2005), and, in particular, after the publication of the influential scientific review paper by frenot et al. (2005), which clearly set out the scale of the non-native species problem in antarctica k.a. hughes & p. convey alien invasions in antarctica citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 5 (page number not for citation purpose) http://www.ats.aq/e/ep.htm http://www.ats.aq/e/ep.htm http://www.polarresearch.net/index.php/polar/rt/suppfiles/22103/0 http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 and the sub-antarctic islands. a workshop entitled nonnative species in antarctica, hosted by new zealand in 2006, further cemented resolve between scientist and policy makers to tackle the issue (new zealand 2006; rogan-finnemore 2008). therefore, although the issue of non-native species introductions may not have been a focus of those who drafted the liability annex, it may also be possible, in principal at least, to use this international instrument for preventing, minimizing and containing the impact of non-native species introductions and to recoup the costs associated with the removal or control of nonnative species that have not been eradicated by those responsible for their introduction. however, when the wording of the liability annex is read in the context of non-native species introductions, it is clear that the annex presents many potential issues for those operating within the antarctic treaty area. at what point does a non-native species introduction become an environmental emergency? an ‘‘environmental emergency’’ is defined as ‘‘an accidental event that results in, or imminently threatens to result in, any significant and harmful impact on the antarctic environment’’ (annex vi, article 2[b]). unlike a catastrophic oil spill, the impacts of which are generally initially great but may dissipate over time, the impacts of non-native species in antarctica may only become apparent long after the initial, usually minor, introduction event (see fig. 1). this temporal element is crucial to the question of whether a non-native species introduction constitutes an environmental emergency under the definitions of the annex. if the annex covers only the immediate consequences of sudden accidents or incidents, as suggested by de la fayette (2010), and not cumulative impact from a continuous situation, then non-native species may fall outside the scope of the annex. taking a different perspective, it could be argued also that an introduced non-native species should not be considered an environmental emergency until it starts to become invasive (i.e., spreads and impacts negatively upon indigenous species and ecosystems) as, before then, impacts are likely to be trivial and limited in spatial scale. non-native species may remain in a persistent state (i.e., surviving and reproducing at a restricted locality, with no expansion of the area colonized over time) for many years before either some genetic change occurs or a physiological threshold is crossed that allows it to become invasive (olech 2003; frenot et al. 2005; hughes & worland 2010; olech & chewedorzewska 2011). for example, climate warming may increase the likelihood of a non-native plant switching to invasive status and spreading more widely, as has already been observed in an analogous fashion with recent population expansion in some indigenous plants on the antarctic peninsula (fowbert & smith 1994; convey 2006; parnikoza et al. 2009). with adequate long-term monitoring, the onset of this switch could be detected and the ‘‘imminent threat’’ of ‘‘significant and harmful impact on the antarctic environment’’ might make the annex applicable. however, from a practical perspective, rather than initiating a long-term monitoring programme focussed on a newly discovered non-native species, it would likely be less effort to simply eradicate the species as soon after its discovery as possible, as recommended by the cep (2011). consequently, there is a potential case that the presence of even a single individual of a confirmed non-native species should be considered an ‘‘environmental emergency in waiting,’’ and trigger prompt management action, thereby pre-empting the potential application of annex vi (which itself states that response action by an operator that has caused an environmental emergency should be prompt and effective [article 5]). if left unmanaged the non-native species may replicate, spread and become invasive before eradication can be funded, planned and attempted (as has already likely occurred with the grass poa annua near arctowski station, king george island, and the flightless midge eretmoptera murphyi on signy island, south orkney islands (hughes, worland et al. 2013). fig. 1 schematic representation of the relative impacts over time of two serious environmental emergencies: marine oil spill and introduction of an invasive species to antarctica. oil spills at sea may cause substantial damage to local wildlife, but with time, the oil evaporates or dissipates and impacts generally become reduced. in contrast, the environmental impacts associated with the early stages of colonization by a non-native species are low or non-existent, but should the organism become established and then invasive, the consequences for indigenous biological communities may be widespread, irreversible and the impact significantly greater than minor or transitory. alien invasions in antarctica k.a. hughes & p. convey 6 (page number not for citation purpose) citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 when will the annex come into effect? although the liability annex has been adopted as a legally binding measure, it will not enter into force until the consultative parties have approved it (article 2[b]). approval of each consultative party takes place when it deposits a note signifying its approval of the international instrument with the depositary government of the antarctic treaty. however, the process of approval differs between parties. for some parties, such as the uk, an international instrument is only approved once it has been incorporated into domestic law. however, for other parties approval is the same as initial adoption; for example, chile and south africa have adopted and, therefore, approved the protocol on environmental protection to the antarctic treaty whilst still not having passed it fully into domestic legislation. in the past the parties have been slow in making adopted international instruments effective. for example, atcm recommendation xviii-1, which provides guidelines for tourism, is still not effective 20 years after it was adopted initially at kyoto in 1994. measure 1 (2005) concerns the liability annex, and so far only eight parties have approved the measure out of the 28 parties that adopted it in 2005, making it unlikely that the annex will become effective within the next decade. as the annex cannot be applied retrospectively, all non-native species known already to be present in antarctica*some of which were almost certainly introduced by, for example, argentina, poland, the uk and uruguay (corte 1961; olech 1996; hughes & worland 2010; volonterio et al. 2013)*and any introduced in the years until the annex comes into force will not be subject to this annex. preventative measures and response action given an assumption that the liability annex might be applicable to non-native species introductions at some stage, the annex states that any preventative measures and response action should be ‘‘reasonable,’’ taking into consideration the ‘‘rate of natural recovery’’ of the antarctic environment, and also be technologically and economically feasible (article 2[e]). once a species is introduced, natural recovery of the antarctic environment to its pre-introduction state may occur if the species dies out, most likely due to physical factors; however, should a species become invasive then ongoing habitat alteration, rather than natural recovery, may occur over time. the longer a non-native species is allowed to persist in antarctica, the more likely it is that its distribution range will increase both through natural processes and by further anthropogenic transfer. therefore, if no action is taken by either the responsible operators or another operator at some point following the introduction, eradication of a non-native species may become neither technologically nor economically feasible. annex ii requires that ‘‘each party shall require that precautions, including those listed in appendix c to this annex, be taken to prevent the introduction of microorganisms (e.g., viruses, bacteria, parasites, yeasts, fungi) not present in the native fauna and flora.’’ while it is important that measures are taken to prevent microbial introductions (including pathogenic species that may cause disease in wildlife), once introduced, eradication would likely be unfeasible or impossible, in contrast to an introduced macro-organism such as a grass or invertebrate, which may realistically be controlled by eradication attempts. measures to reduce the risk of an environmental emergency parties are required to ensure their operators take measures to reduce the risk of environmental emergencies and their potential adverse impacts (annex vi, article 3). listed measures include the following: (1) ‘‘specialised structures or equipment incorporated into . . . facilities and means of transport,’’ which in the context of non-native species could include designated quarantine areas for the inspection or storage of imported material, or equipment for removing propagules from cargo and equipment; (2) ‘‘specialised procedures incorporated into the operation and maintenance of facilities and means of transport,’’ which could include appropriate biosecurity procedures; and (3) ‘‘specialised training of personnel,’’ which could include education on the risk associated with non-native species and steps that can be taken to reduce this risk (e.g., cleaning of cargo, vehicles and equipment, boot washing and careful management of fresh foods [see comnap & scar 2010]). contingency planning article 4 sets out the need for contingency plans to help respond to environmental emergencies but, to date, little discussion of practical contingency planning has occurred within the cep or comnap with regard to non-native species and it is doubtful that many, if any, such contingency plans exist within the treaty parties. however, the cep non-native species manual (cep 2011), which provides information and non-mandatory guidelines on non-native species and biosecurity, does mention the preparation of a ‘‘rapid response guideline’’ as an area of potential future work (see annex i, point 17). k.a. hughes & p. convey alien invasions in antarctica citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 allocation of liability and reclaiming costs the voluntary cep non-native species manual (cep 2011) states that ‘‘responses to introductions should be undertaken as a priority, to prevent an increase in the species’ distribution range and to make eradication simpler, cost effective and more likely to succeed.’’ however, assuming an introduction can be attributed to the actions of an operator, and that eradication is feasible and would not itself cause excessive environmental damage, it is unlikely that the responsible operator could be compelled to eradicate the non-native species under annex ii alone. articles 6 and 7 of annex vi concern the allocation of liability following an environmental emergency and legal actions to reclaim costs. if non-native species are eradicated at the earliest stages of introduction, costs are likely to be trivial in comparison with the larger-scale actions required inevitably once a species has become established over a larger area. however, if a non-state operator does not take these initial eradication steps, it is feasible that a different party could suggest that they intend to undertake a response action (i.e., eradication) and reclaim costs through the domestic courts using national legislation that incorporates the liability annex into national law, thereby giving the non-state operator a financial incentive to take prompt action to remove the non-native species. as discussed earlier, whether the small scale presence of non-native species consistent with an initial introduction event would constitute an environmental emergency as defined in article 2 may be questioned. if a state operator was responsible for the introduction, its party may be reluctant to engage in a lengthy and potentially timeconsuming engagement with the legal system surrounding annex vi, or to subject themselves to reputational damage, and rather take the potentially simpler and easier option of ensuring eradication at an early stage, as would be required under annex ii, article 3(3c). it is likely that only very clear-cut cases of environmental negligence will be pursued under the annex. it may be difficult to prove*to an appropriate legal standard*responsibility for a non-native species introduction. this may be true particularly at locations under the control of one operator, but visited regularly by ships and/or aircraft belonging to other operators, including those operated by the tourism industry and national operators. examples include fildes peninsula on king george island and, in the same archipelago, deception island, as well as rothera research station, adelaide island. in addition, the potential for colonization via natural pathways may complicate attribution to the operator in question (hughes & convey 2012). who is, or is not, covered by the liability annex? the annex does not apply to fishing vessels and ships transiting through the antarctic treaty area; however, these vessels could be sources of non-native species introductions to the marine environment (article 1). furthermore, the application of the ‘‘sovereign immunity rule’’ whereby ships or aircraft operated by a party for governmental non-commercial activities are beyond the jurisdiction of the annex (article 6[5]), is relevant as the majority of ships and aircraft operating in antarctica are owned or operated by states. nevertheless, state operators are still obliged to take prompt and effective response action and are not exempt from the planning and contingency arrangements in the annex. are the potentially available funds sufficient for adequate non-native species eradication or control? article 9(1b), sets out the limit of liability for an environmental emergency arising from an event which does not involve a ship at three million special drawing rights (currently ca. 4.5 million usd). this should be more than sufficient to undertake a simple one off eradication programme over a limited spatial scale, but may not be adequate for a larger-scale multi-year eradication of a non-native species belonging to a more mobile biological group (e.g., some invertebrates) or one which is able to disperse progeny rapidly. in the marine environment, eradications of marine species are almost always unsuccessful (see iucn 2013), and if attempted in antarctic waters are likely to be extremely expensive. diplomatic concerns in a situation where one party considers it is appropriate to initiate action under the liability annex, the claim will quickly fail if support is not obtained from all other consultative parties, as article 12 states that reimbursements for expenses arising from the response to an environmental emergency shall be approved by way of a decision, which requires consensus agreement by all consultative parties. achieving this level of agreement may be extremely difficult, given the interactions between parties both at and away from the meeting table at the atcms. furthermore, payment of costs from the fund held by the antarctic treaty secretariat relies on the party whose operators caused the environmental emergency also approving the decision to release funds to the party that undertook the response action. in other words, it may be possible for the party found liable to block payment from the fund by not approving the decision. alien invasions in antarctica k.a. hughes & p. convey 8 (page number not for citation purpose) citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 perceived importance of biosecurity issues currently, there is a strong financial incentive for parties to implement strict procedures to prevent a shipping incident (where the ship may be put at risk) or an oil spill (as fuel has a high value in antarctica), as the cost of an incident may be high, even before clean-up costs are taken into consideration. policy makers have highlighted the importance of non-native species issues and have worked with comnap to generate guidelines to reduce the risk of non-native species introductions (comnap & scar 2010; cep 2011). however, the introduction of a non-native species incurs no immediate financial cost to a party, while ongoing biosecurity measures may be considered expensive, inconvenient and time-consuming. as a result biosecurity implementation may not be prioritized, or an introduction even recognized as an environmental emergency with the associated requirements for contingency planning, as laid out in the liability annex. this may leave operators open to later potential claims. are eradication attempts always justified? there are well-considered arguments for rapid action following the identification of an anthropogenically introduced non-native species within the treaty area, specifically to prevent further spread (see fig. 1). however, over-zealous removal of ‘‘supposed’’ non-native species without appropriate research may be problematic and in some instances may prevent natural colonization when mistakes are made (hughes & convey 2012). in another scenario, if a non-native species eradication is likely to cause substantial damage to the indigenous biota in the affected area, it may be difficult to justify approving the introduced species’ removal. for instance, following years of inaction regarding the establishment of poa annua on king george island (olech & chwedorzewska 2011) and the chironomid midge eretmoptera murphyi and the enchytraeid worm christensenidrilus blocki on signy island (hughes & worland 2010), it could be argued that the scale of damage that would now inevitably be caused to local ecosystems by any eradication attempt cannot be justified. this illustrates a situation in which different interpretations of annex ii come into conflict. for example, attempting the eradication of a non-native species using methods normally used elsewhere (such as digging up or use of herbicides or pesticides) may damage habitats which, within the area concerned, would be contrary to the annex ii requirement to maintain the species diversity, habitat and balance of antarctic ecological systems (article 3[3c]). crucially, however, should the invasive species not be eradicated and, rather, be spread to other antarctic locations, far greater impacts might result over a considerably larger spatial scale. there are no guidelines on how to deal with the conflicts arising from the implementation of the environmental protocol, although the issue has been identified as an area for further work by the cep (2011). other legal issues may need consideration before eradications may proceed. pesticides, which may be essential for successful eradications, are not permitted within the treaty area other than for ‘‘scientific, medical or hygiene purposes’’ (annex iii, article 7). furthermore, permits can be given by appropriate national authorities to undertake harmful interference with native flora and fauna, but only (1) to provide specimens for scientific study, (2) to supply specimens for museums and other educational establishments, or (3) to ‘‘provide for the unavoidable consequence of scientific activities . . . or of the construction and operation of scientific support facilities.’’ can we consider the introduction of a non-native species an ‘‘unavoidable’’ consequence of our activities in antarctica? parties may see environmental impacts as an inevitable consequence of undertaking science in antarctica and justified by the benefits this research brings. it may be more difficult to justify any introductions that come about through tourist activities, from this perspective. such complications may make parties reluctant to resort to potentially costly enquiry procedures or arbitration, as described in annex vi, article 7(5a). failed eradication attempts the non-native black fungus midge lycoriella sp. was first reported to have colonized the sewage system at casey station (australia) in 1998, but several subsequent attempts to eradicate it have failed (hughes et al. 2005). in the case of some other species, the likelihood of a successful eradication might also be low. for example, the fly trichocera maculipennis found recently both in the sewage system and outside the uruguayan general artigas station on fildes peninsula (volonterio et al. 2013) may be virtually impossible to eradicate now, given that it is a flying insect that has probably established in the environment, and is likely to be highly pre-adapted to maritime antarctic conditions given its natural distribution, including high-latitude boreal locations. it may be that a party could reclaim costs from an operator responsible for an introduction, even if the party’s response action was ultimately unsuccessful, as it could be claimed that full eradication is impossible in practical terms, but that management action to control or limit spread of the species was taken instead. however, longer term control and management will not be chargeable as liability of the operator ends 15 years after the initiation of the response action (article 7[1]). k.a. hughes & p. convey alien invasions in antarctica citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 environmental emergencies resulting from food importation and cultivation currently, the importation of foods (excluding livestock) for human consumption within antarctica is not subject to the measures to prevent intentional non-native species introductions set out in annex ii, article 4, of the protocol (‘‘introduction of non-native species, parasites and diseases’’). however, it should be noted that the exemption of food products from article 4 is only granted provided that foods are kept under carefully controlled conditions and are disposed of in accordance with annex iii (‘‘waste disposal and waste management’’) and appendix c to annex ii (‘‘precautions to prevent introductions of microorganisms’’). it is unclear if parties that fail to conform with these requirements, with the result that a non-native species becomes introduced to the antarctic environment, could be held liable under the liability annex. furthermore, hydroponic facilities present at several antarctic research stations have in the past been closed down due to infestations by non-native invertebrates, and it is possible that these species may be released outside the hydroponic facility, as has happened within the sub-antarctic islands (frenot et al. 2005; greenslade 2006; hughes & convey 2012; comnap 2013b). such environmental incidents highlight the need for adequate contingency planning, which is also a requirement of the liability annex. conclusions given the potential threat to antarctic marine and terrestrial ecosystems presented by the introduction of non-native species, the atcm (and in particular through the cep) has devoted considerable time to raising awareness of the risks presented by non-native species and to developing guidelines to reduce the risk of non-native species impacts. however, much of this work took place in the years after the liability annex was adopted in 2005. therefore, it is likely that those who drafted the liability annex did not appreciate fully the broad range of environmental emergencies that could arise, and were focussing predominantly on (particularly, catastrophic) pollution events and not on non-native species impacts. the slow pace of approval of the liability annex by antarctic treaty parties, so far, may prevent the instrument coming into force for many years. furthermore, even once the annex enters into force, in its current form it is unlikely to be useful for reclaiming costs associated with the eradication or management of a non-native species, due particularly to a lack of clarity on the scope of the annex and the complex nature of non-native species invasions. the atcm’s decision 4 (2010), concerning ‘‘liability arising from environmental emergencies,’’ asked the cep ‘‘to consider environmental issues related to the practicality of repair or remediation of environmental damage in the circumstances of antarctica, in order to assist the atcm in adopting an informed decision in 2015 related to the resumption of the negotiations.’’ this decision presents a useful opportunity for the issues relating to environmental emergencies and liability concerning non-native species (many of which have been highlighted here) to be considered more fully. however, given the vulnerability of antarctic ecosystems to non-native species, it is hoped that biosecurity standards improve across all parties and operators long before these negotiations conclude. acknowledgements this paper contributes to the british antarctic survey (bas) polar science for planet earth ecosystems programme, the bas environment office long term monitoring and survey project and the state of the antarctic ecosystem research programme of the scientific committee on antarctic research. we thank jane rumble, akbar khan and henry burgess for helpful discussions on the liability annex and two anonymous reviewers for extremely useful and thought provoking comments, which greatly improved this work. references aronson r.b., thatje s., mcclintock j.b. & hughes k.a. 2011. anthropogenic impacts on marine ecosystems in antarctica. annals of the new york academy of sciences 1223, 82�107. aust a. & shears j. 1996. liability for environmental damage in antarctica. review of european community and international environmental law 5, 312�320. australia 2004. establishment of effective antarctic quarantine controls for tourism and other non-government activities. working paper 21. rev. 1. xxvii antarctic treaty consultative meeting, vii committee for environmental protection. 24 may�4 june 2004, cape town. australia 2005. measures to address the unintentional introduction and spread of non-native biota and disease to the antarctic treaty area. working paper 28. xxviii antarctic treaty consultative meeting, viii committee for environmental protection. 6�17 june 2005, stockholm. bargagli r. 2005. antarctic ecosystems: environmental contamination, climate change, and human impact. berlin: springer. cep (committee for environmental protection) 2011. nonnative species manual. 1st edn. buenos aires: antarctic treaty secretariat. chile 2008. background to the pollution incident caused by the sinking of the ms explorer. information paper 11. xxxi alien invasions in antarctica k.a. hughes & p. convey 10 (page number not for citation purpose) citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 antarctic treaty consultative meeting, xi committee for environmental protection. 2�13 june 2008, kiev. chown s.l., huiskes a.h.l., gremmen n.j.m., lee j.e., terauds a., crosbie k., frenot y., hughes k.a., imura s., kiefer k., lebouvier m., raymond b., tsujimotoi m., ware c., van de vijver b. & bergstrom d.m. 2012. continentwide risk assessment for the establishment of nonindigenous species in antarctica. proceedings of the national academy of sciences 109, 4938�4943. chown s.l., lee j.e., hughes k.a., barnes j., barrett p.j., bergstrom d.m., convey p., cowan d.a., crosbie k., dyer g., frenot y., grant s.m., herr d., kennicutt m.c., lamers m., murray a., possingham h.p., reid k., riddle m.j., ryan p.g., sanson l., shaw j.d., sparrow m.d., summerhayes c., terauds a. & wall d.h. 2012. challenges to the future conservation of the antarctic. science 337, 158�159. clarke a. & johnston n.m. 2003. antarctic marine benthic diversity. oceanography and marine biology: an annual review 41, 47�114. comnap (council of managers of national antarctic programs) 2013a. antarctic information. accessed on the internet at https://www.comnap.aq/information/sitepages/ home.aspx on 6 june 2014. comnap (council of managers of national antarctic programs) 2013b. use of hydroponics by national antarctic programs. information paper 31. xxxvi antarctic treaty consultative meeting, xvi committee for environmental protection. 20�29 may 2013, brussels. comnap (council of managers of national antarctic programs) & scar (scientific committee on antarctic research) 2010. checklists for supply chain managers of national antarctic programmes for the reduction in risk of transfer of non-native species. christchurch: comnap. convey p. 1996. the influence of environmental characteristics on the life history attributes of antarctic terrestrial biota. biological reviews 71, 191�225. convey p. 2006. antarctic climate change and its influences on terrestrial ecosystems. in d. bergstom et al. (eds.): trends in antarctic terrestrial and limnetic ecosystems. pp. 253�272. dordrecht, the netherlands: springer. convey p. 2008. non-native species in antarctic terrestrial and freshwater environments: presence, sources, impacts and predictions. in m. rogan-finnemore (ed.): non-native species in the antarctic: proceedings. pp. 97�130. christchurch: gateway antarctica. convey p. 2011. antarctic terrestrial biodiversity in a changing world. polar biology 34, 1629�1641. convey p. 2013. antarctic ecosystems. in s.a. levin (ed.): encyclopedia of biodiversity. vol. 1. 2nd edn. pp. 179�188. san diego: elsevier. convey p., gibson j.a.e., hillenbrand c.-d., hodgson d.a., pugh p.j.a., smellie j.l. & stevens m.i. 2008. antarctic terrestrial life*challenging the history of the frozen continent? biological reviews 83, 103�117. convey p., hughes k.a. & tin t. 2012. continental governance and environmental management mechanisms under the antarctic treaty system: sufficient for the biodiversity challenges of this century? biodiversity 13, 1�15. convey p. & stevens m.i. 2007. antarctic biodiversity. science 317, 1877�1878. convey p., stevens m.i., hodgson d.a., smellie j.l., hillenbrand c.-d., barnes d.k.a., clarke a., pugh p.j.a., linse k. & cary s.c. 2009. exploring biological constraints on the glacial history of antarctica. quaternary science reviews 28, 3035�3048. corte a. 1961. la primera fanerógama adventicia hallada en el continente antártico. (the first flowering plant found adventitiously on the antarctic continent.) contribución del instituto antártico argentino 62, 1�14. cowan d.a., chown s.l., convey p., tuffin m., hughes k.a., pointing s. & vincent w.f. 2011. non-indigenous microorganisms in the antarctic*assessing the risks. trends in microbiology 19, 540�548. de la fayette l.a. 2010. international liability for damage to the environment. in m. fitzmaurice et al. (eds.): research handbook on international environmental law. pp. 320�360. cheltenham, uk: edward elgar publishing. fasham m. & trumper k. 2001. review of non-native species legislation and guidance. bristol: uk department for environment, food & rural affairs. fowbert j.a. & smith r.i.l. 1994. rapid population increase in native vascular plants in the argentine islands, antarctic peninsula. arctic and alpine research 26, 290�296. frenot y., chown s.l., whinam j., selkirk p.m., convey p., skotnicki m. & bergstrom d.m. 2005. biological invasions in the antarctic: extent, impacts and implications. biological reviews 80, 45�72. greenslade p. 2006. the invertebrates of macquarie island. kingston: australian antarctic division. greenslade p., potapov m., russell d. & convey p. 2012. global collembola on deception island. journal of insect science 12, article no. 111. hughes k.a. & convey p. 2010. the protection of antarctic terrestrial ecosystems from interand intra-continental transfer of non-indigenous species by human activities: a review of current systems and practices. global environmental change 20, 96�112. hughes k.a. & convey p. 2012. determining the native/nonnative status of newly discovered terrestrial and freshwater species in antarctica*current knowledge, methodology and management action. journal of environmental management 93, 52�66. hughes k.a., convey p., maslen n.r. & smith r.i.l. 2010. accidental transfer of non-native soil organisms into antarctica on construction vehicles. biological invasions 12, 875�891. hughes k.a., fretwell p., rae j., holmes k. & fleming a. 2011. untouched antarctica: mapping a finite and diminishing environmental resource. antarctic science 23, 537�548. hughes k.a., huiskes a.h.l. & convey p. 2014. global movement and homogenisation of biota: challenges to the environmental management of antarctica? in t. tin et al. (eds.): antarctic futures: human engagement with the antarctic environment. pp. 113�137. dordrecht, the netherlands: springer. k.a. hughes & p. convey alien invasions in antarctica citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 11 (page number not for citation purpose) https://www.comnap.aq/information/sitepages/home.aspx https://www.comnap.aq/information/sitepages/home.aspx http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 hughes k.a. & lawley b. 2003. a novel antarctic microbial endolithic community within gypsum crusts. environmental microbiology 5, 555�565. hughes k.a., lee j.e., tsujimoto m., imura s., bergstrom d.m., ware c., lebouvier m., huiskes a.h.l., gremmen n.j.m., frenot y., bridge p.d. & chown s.l. 2011. food for thought: risks of non-native species transfer to the antarctic region with fresh produce. biological conservation 144, 1682�1689. hughes k.a., walsh s., convey p., richards s. & bergstrom d.m. 2005. alien fly populations established at two antarctic research stations. polar biology 28, 568�570. hughes k.a. & worland m.r. 2010. spatial distribution, habitat preference and colonisation status of two alien terrestrial invertebrate species in antarctica. antarctic science 22, 221�231. hughes k.a., worland m.r., thorne m. & convey p. 2013. the non-native chironomid eretmoptera murphyi in antarctica: erosion of the barriers to invasion. biological invasions 15, 269�281. hulme p.e., bacher s., kenis m., klotz s., kühn i., minchin d., nentwig w., olenin s., panov v., pergl j., pyšek p., roques a., sol d., solarz w. & vilà m. 2008. grasping at the routes of biological invasions: a framework for integrating pathways into policy. journal of applied ecology 45, 403�414. international association of antarctica tour operators 2013. tourism statistics. accessed on the internet at http://iaato. org/tourism-statistics on 4 june 2013. iucn (international union for the conservation of nature) 2013. marine menace*alien invasive species in the marine environment. gland, switzerland: international union for the conservation of nature. kennedy a. 1993. water as a limiting factor in the antarctic terrestrial environment: a biogeographical synthesis. arctic and alpine research 25, 308�315. kennicutt m.c. & sweet s.t. 1992. hydrocarbon contamination in the antarctic peninsula. iii: the bahia paraiso*two years after the spill. marine pollution bulletin 25, 303�306. kennicutt m.c., sweet s.t., fraser w.r., stockton w.l. & culver m. 1991. grounding of the bahia paraiso at arthur harbor, antarctica. i. distribution and fate of oil spill related hydrocarbons. environmental science and technology 25, 509�518. lee j.e. & chown s.l. 2007. mytilus on the move: transport of an invasive bivalve to the antarctic. marine ecology progress series 339, 307�310. lee j.e. & chown s.l. 2009a. breaching the dispersal barrier to invasion: quantification and management. ecological applications 7, 1944�1959. lee j.e. & chown s.l. 2009b. quantifying the propagule pressure associated with the construction of an antarctic research station. antarctic science 21, 471�475. lewis p.n., bergstrom d.m. & whinam j. 2006. barging in: a temperate marine community travels to the subantarctic. biological invasions 8, 787�795. lewis p.n., hewitt c.l., riddle m. & mcminn a. 2003. marine introductions in the southern ocean: an unrecognised hazard to biodiversity. marine pollution bulletin 46, 213�223. manchester s.j. & bullock j.m. 2000. the impacts of nonnative species on uk biodiversity and the effectiveness of control. journal of applied ecology 37, 845�864. miller c., kettunen m. & shine c. 2006. scope options for eu action on invasive alien species (ias). final report for the european commission. brussels: institute for european environmental policy. molina-montenegro m.a., carrasco-urra f., rodrigo c., convey p., valladares f. & gianoli e. 2012. occurrence of the non-native annual bluegrass on the antarctic mainland and its negative effects on native plants. conservation biology 26, 717�723. new zealand 2006. non-native species in the antarctic. report of a workshop. working paper 13. xxix antarctic treaty consultative meeting, ix committee for environmental protection. 12�23 june 2006, edinburgh. olech m. 1996. human impact on terrestrial ecosystems in west antarctica. proceedings of the nipr symposium on polar biology 9, 299�306. olech m. 2003. expansion of alien vascular plant poa annua l. in the vicinity of the henryk arctowski station*a consequence of climate change? in m. olech (ed.): the functioning of polar ecosystems as viewed against global environmental changes. xxix international polar symposium. pp. 89�90. krakow: jagiellonian university. olech m. & chwedorzewska k.j. 2011. the first appearance and establishment of an alien vascular plant in natural habitats on the forefield of a retreating glacier in antarctica. antarctic science 23, 153�154. parnikoza i., convey p., dykyy i., trakhimets v., milinevsky g., tyschenko o., inozemtseva d. & kozeretska i. 2009. current status of the antarctic herb tundra formation in the central argentine islands. global change biology 15, 1685�1693. peck l.s., convey p. & barnes d.k.a. 2006. environmental constraints on life histories in antarctic ecosystems: tempos, timings and predictability. biological reviews 81, 75�109. pertierra l.r, lara f., benyas j. & hughes k.a. 2013. poa pratensis l., current status of the longest-established nonnative vascular plant in the antarctic. polar biology 36, 1473�1481. pugh p.j.a. & convey p. 2008. surviving out in the cold: antarctic endemic invertebrates and their refugia. journal of biogeography 35, 2176�2186. rogan-finnemore m. (ed.): 2008. non-native species in the antarctic*proceedings. christchurch, new zealand: gateway antarctica. shine c., williams n. & gundling l. 2000. a guide to designing legal and institutional frameworks on alien invasive species. gland, switzerland: international union for the conservation of nature. smith r.i.l. 1996. introduced plants in antarctica: potential impacts and conservations issues. biological conservation 76, 135�146. alien invasions in antarctica k.a. hughes & p. convey 12 (page number not for citation purpose) citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 http://iaato.org/tourism-statistics http://iaato.org/tourism-statistics http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 steig e.j., schneider d.p., rutherford s.d., mann m.e., comiso j.c. & shindell d.t. 2009. warming of the antarctic ice-sheet surface since the 1957 international geophysical year. nature 457, 459�462. terauds a., chown s.l., morgan f., peat h.j., watts d.j., keys h., convey p. & bergstrom d.m. 2012. conservation biogeography of the antarctic. diversity and distribution 18, 726�741. tin t., fleming z.l., hughes k.a., ainley d.g., convey p., moreno c.a., pfeiffer s., scott j. & snape i. 2009. impacts of local human activities on the antarctic environment. antarctic science 21, 3�33. tin t., liggett d., maher p. & lamers m. 2013. the future of antarctica: human impacts, strategic planning and values for conservation. dordrecht, the netherlands: springer. tsujimoto m. & imura s. 2012. does a new transportation system increase the risk of importing non-native species to antarctica? antarctic science 24, 441�449. turner j., bindschadler r., convey p., di prisco g., fahrbach e, gutt g., hodgson d., mayewski p. & summerhayes c. (eds.): 2009. antarctic climate change and the environment. cambridge, uk: scientific committee on antarctic research. united kingdom 2006. practical guidelines for ballast water exchange in the antarctic treaty area. working paper 5. xxix antarctic treaty consultative meeting, ix committee for environmental protection. 12�23 june 2006, edinburgh. united kingdom 2013. colonisation status of known nonnative species in the antarctic terrestrial environment. information paper 28. xxxvi antarctic treaty consultative meeting, xvi committee for environmental protection. 20�29 may 2013, brussels. vincent w.f. 1988. microbial ecosystems of antarctica. cambridge, uk: cambridge university press. volonterio o., de león r.p., convey p. & krzeminska e. 2013. first record of trichoceridae (diptera) in the maritime antarctic. polar biology 36, 1125�1131. vöneky s. 2008. the liability annex to the protocol on environmental protection to the antarctic treaty. in d. könig et al. (eds.): international law today: new challenges and the need for reform. pp. 165�194. berlin: springer. wilkness p. 1990. fuel spill clean up in the antarctic. antarctic journal of the united states 25, 3�8. wynn-williams d.d. 1996. antarctic microbial diversity: the basis of polar ecosystem processes. biodiversity and conservation 5, 1271�1293. k.a. hughes & p. convey alien invasions in antarctica citation: polar research 2014, 33, 22103, http://dx.doi.org/10.3402/polar.v33.22103 13 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22103 http://dx.doi.org/10.3402/polar.v33.22103 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice no job name clay mineral cycles identified by diffuse spectral reflectance in quaternary sediments from the northwind ridge: implications for glacial–interglacial sedimentation patterns in the arctic oceanpor_160 176..197 lyanne n. yurco,1 joseph d. ortiz,2 leonid polyak,3 dennis a. darby4 & kevin a. crawford3 1 rosenstiel school of marine and atmospheric science, university of miami, miami, fl 33149, usa 2 department of geology, kent state university, kent, oh 44242, usa 3 byrd polar research center, ohio state university, columbus, oh 43210, usa 4 old dominion university, norfolk, va 23529, usa abstract a quaternary record of fine-grained sediment composition is used to investigate arctic ocean climate variability on glacial–interglacial time scales. diffuse spectral reflectance data from sediment core p1-92ar-p25 from the northwind ridge, north of alaska, demonstrates cyclic variations in mineralogy. varimaxrotated r-mode factor analysis of down-core data revealed three major mineralogical assemblages, which were then compared with the content of manganese, a proxy for basin ventilation, and thus glacial–interglacial cycles. results indicate that factor 1, a smectite + chlorite clay assemblage, was delivered to the core site during interglacials, either by fluvial discharge or sea-ice drift from siberian rivers or inflow from the bering sea. factor 2, an illite + goethite assemblage, is related to glacial periods, and was probably transported from the laurentide ice sheet by icebergs or meltwater. factor 3, glauconite, might have been sourced from the north slope region of alaska during deglacial intervals, or from dolomites associated with laurentide iceberg-discharge pulses. the observed variations in sediment source and transport mechanisms arise from glacial–interglacial changes in sea level, the size of the terrestrial ice sheets surrounding the arctic ocean, the extent of sea-ice cover and altered atmospheric circulation. the reconstructed glacial– interglacial circulation patterns from the late quaternary show some similarity with modern circulation changes presumably related to the monthlyto decadally-fluctuating arctic oscillation. however, because the arctic oscillation operates on much shorter time scales, further research is necessary to better understand the driving mechanism for the changes observed over glacial– interglacial cycles, and the potential role of ocean–atmospheric interaction. keywords arctic ocean quaternary palaeoclimate; arctic oscillation; clay mineral provenance; glacial–interglacial cycles; diffuse spectral reflectance; r-mode factor analysis. correspondence lyanne n. yurco, rosenstiel school of marine and atmospheric science, university of miami, miami, fl 33149, usa. e-mail: lyurco@rsmas.miami.edu doi:10.1111/j.1751-8369.2010.00160.x focus on the arctic has increased in recent years in an attempt to better understand climate change. a major reason for this is the region’s climatic sensitivity, which enables us to see dramatic changes on annual to decadal time scales. for example, september 2007 marked a new minimum in sea-ice extent as a result of a warming climate and changing atmospheric conditions (comiso et al. 2008). not only is the arctic sensitive to climate change, but it has the ability to amplify changes globally. the melting of ice contributes to a positive albedo feedback, augmenting the warming process and fuelling more melting. also, the addition of freshwater from melting ice can alter north atlantic deep water formation, affecting global ocean circulation and, consequently, the earth’s climate (holland et al. 2001; curry & mauritzen 2005). arctic ocean sediment provides palaeoceanographic evidence of past climatic conditions that may help us better understand the changing arctic climate system, which remains poorly understood. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd176 mailto:lyurco@rsmas.miami.edu sedimentation in the arctic ocean is affected by glacial cycles, sea-ice coverage, ocean circulation and atmospheric conditions, and thus provides a record of their combined effect. changes in sea-ice extent can affect the amount and type of sedimentation, sea level and glaciations influence source regions and delivery mechanisms, and circulation directly impacts transportation pathways. these interrelated variables are also tied to atmospheric conditions. for example, the arctic oscillation (ao), as discussed below, has been shown to modulate sea-ice circulation, extent and thickness on seasonal–decadal, and perhaps longer, time scales (kwok 2000; polyakov & johnson 2000; rigor et al. 2002; polyakov et al. 2003; serreze et al. 2003; zhang et al. 2003; darby & bischof 2004). studying the interaction of these climatic processes and their variability over glacial–interglacial time scales can provide us with a better understanding of the long-term natural changes in the arctic. seeking to use the sedimentary record to unravel arctic climate conditions, and their cyclic variations during glacial–interglacial periods of the late pleistocene, this study examines a sediment core from the northwind ridge in the amerasian basin, about 300 km north of alaska. we present a record of cyclic clay mineral variations that correspond to cold, glacial conditions and warm, interglacial conditions. clay minerals in the arctic have been used as provenance indicators, as they tend to occur in geographically distinct regions (clark et al. 1980; naidu & mowatt 1983; dalrymple & maass 1987; darby et al. 1989; petschick et al. 1996; vogt 1997; winter et al. 1997; wahsner et al. 1999; kalinenko 2001; viscosishirley, mammone et al. 2003; viscosi-shirley, pisias et al. 2003; stein et al. 2004; stein 2008). by comparing clay mineral assemblages with a glacial–interglacial climate record, we can interpret potential transport mechanisms and pathways, and thus piece together an understanding of the dynamic climate processes that contributed to the sediment record. geologic and oceanographic setting core p1-92ar-p25, hereafter referred to as p25, was collected by the us geological survey from the east slope of the northwind ridge (eastern ridge of the chukchi borderland) from a water depth of 1625 m (fig. 1) (arctic summer west scientific party 1993). because of its proximity to sediment sources and the sea-ice margin, resulting in elevated sedimentation rates on the southern northwind ridge, this site provides a more expanded and better resolved palaeoclimatic section in comparison with many sites from the interior of the arctic ocean (polyak et al. 2009). the transport of sediment in the arctic ocean (except for turbidites) is mostly influenced by the surface circulation of sea ice and icebergs (clark et al. 1980; bischof & darby 1997; phillips & grantz 2001), but fine-grained silts and clays can also be transported or redeposited by currents in intermediate or deep waters (hunkins et al. 1969; winkler et al. 2002). in the arctic ocean today, there are two major surface current systems: the trans-polar drift (tpd) that moves from the siberian shelf towards the fram strait, across the eurasian basin, and the beaufort gyre (bg), a clockwiserotating current system that dominates the circulation in the amerasian basin (colony & thorndike 1984) (fig. 1). besides the effect of the tpd and bg surface currents, the p25 core site may be influenced by the northflowing current through the bering strait that flows across the chukchi sea west of the chukchi borderland (weingartner et al. 2005). this current turns east, and is incorporated into an eastward flow formed by brine rejection during freeze-up, that forms part of the beaufort undercurrent (bu) at depths below about 50 m to perhaps 2500 m (aagaard 1984; weingartner et al. 2005; woodgate et al. 2005). whether the bu actually flows along the northwind scarp, where p25 is located, is uncertain. high-density plumes formed by brine rejection along with comparably infrequent turbidity flows are thought to be the primary origin of deep water in the canada basin. it is the warmest and saltiest deep water in the arctic ocean (campbell & clark 1977; aagaard et al. 1985), and because salinity also increases with depth in the basin, the high salinity waters cannot originate from adjacent basins or the upper water column. instead, they must be derived from the continental shelf, where salt rejection during freezing creates dense brines, which mix with colder water from below to form deep water plumes (aagaard et al. 1985). these brine rejection density flows can carry sediments to great depths, and may provide a means of their transport to the p25 site. in addition, intermediate currents can affect sedimentation. warm water from the atlantic, originating in the norwegian current, enters the arctic ocean via two branches: the fram strait branch (the west spitsbergen current) and the barents sea branch. these branches cool and sink to intermediate depths, meeting north of the kara sea, and flowing cyclonically throughout the deep basins as narrow boundary currents along the continental slopes and ridges. however, only the barents sea branch reaches the southern canada basin (and the northwind ridge) beyond the chukchi cap (rudels et al. 1994; rudels et al. 2004) (fig. 1). methods diffuse spectral reflectance (dsr) measurements were made on the surface of the entire p25 core using a clay mineral cycles from the northwind ridgel.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 177 minolta cm-2600d ultraviolet/visible spectrophotometer (konica minolta, tokyo, japan). see ortiz et al. (2009) for detailed procedures. measurements were made in the visible light spectrum (400–700 nm), and are used as a reference for our sample subset. as the primary focus for this study, samples were selected from marine isotope stages (mis) 3–6, as this section of the core contains the most prominent down-core glacial–interglacial peaks. the age model for this core is derived from a combination of 14c and amino acid racemization (aar) dates, and a multi-proxy correlation with other sediment cores from the western arctic (polyak et al. 2009). along with the 14c and aar ages, the down-core distribution of stratigraphic indicators used to formulate the age model is fig. 1 the international bathymetric chart of the arctic ocean (ibcao) with modern surface circulation patterns, the transpolar drift (tpd) and beaufort gyre (bg), indicated by thick black lines. the white star indicates the location of core p25 on the northwind ridge in the chukchi borderland. intermediate waters that reach the southern canada basin (from rudels et al. 2004) are shown as follows: dashed arrows indicate inflow of atlantic water (aw) and pacific water (pw); black diagonals indicate the area of formation; and thin black arrows indicate the circulation of the barents sea branch halocline, which affects the northwind ridge and site p25; the white box outlines the study site of ortiz et al. (2009). (based on the ibcao map of jakobsson, macnab et al. 2008.) clay mineral cycles from the northwind ridge l.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd178 shown in fig. 2, and include: palaeomagnetic inclination, sand content (>63 mm in diameter) and foraminiferal numbers. this age model is further confirmed by the elevated content of subpolar species among planktonic foraminifers in mis 5, consistent with earlier results from other sites in the arctic ocean (nørgaard-pedersen et al. 2007; adler et al. 2009), and by the prominent inclination drop demonstrated to occur in mis 7 (polyak et al. 2009). the ages for mis boundaries are taken from martinson et al. (1987). fig. 2 (a) down-core distribution of stratigraphic indicators used by polyak et al. (2009) to construct the age model for the core p25: palaeomagnetic inclination, sand content (>63 mm in diameter), foraminiferal numbers, and 14c and amino-acid racemization (aar) ages. palaeomagnetic data and 14c/aar ages are from polyak et al. (2009). the prominent inclination drop has been demonstrated to occur in marine isotope stage (mis) 7 (polyak et al. 2009). the inferred mis boundaries and ages are shown on the right. (b) age–depth plot for core p25. grey diamonds represent 14c and 14c-calibrated aar ages (adler et al. 2009), and black squares represent specmapcorrelated mis picks based on multi-proxy correlation of several western arctic cores (polyak et al. 2009). specmap mis ages are taken from martinson et al. (1987). the dashed line with open circles represents the composite age model for core p25. clay mineral cycles from the northwind ridgel.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 179 the dsr measurements were also made on the subset of discrete samples for comparison. statistical analysis of dsr data was conducted on the siliciclastic terrigenous component, in order to extract information regarding variations in clay mineral assemblages from the carbonate-free sediment. clay minerals have been shown to occupy geographically distinct regions in the arctic (e.g., clark et al. 1980; naidu & mowatt 1983; dalrymple & maass 1987; darby et al. 1989; wahsner et al. 1999; kalinenko 2001; viscosi-shirley, mammone et al. 2003; viscosi-shirley, pisias et al. 2003; stein et al. 2004; stein 2008; vogt 2009; vogt & knies 2009), and are here used to evaluate provenance and circulation changes during glacial–interglacial periods. the down-core samples taken from the core were mixed with 0.2% sodium hexametaphosphate, in order to avoid flocculation (mccave et al. 2005), and were washed, sieved and dried. we conducted measurements on both bulk sediment and sediment residues following an acid-base treatment. following mccave et al. (2005), a treatment of 5 ml of glacial acetic acid was applied to about 0.2 g of the dried <63-mm-diameter samples, to remove carbonate, followed by about 40 ml of 2 m na2co3, to remove biogenic opal. the samples were then neutralized with 10 ml of glacial acetic acid. the acid–base treatment was applied in order to isolate the terrigenous component of the fine fraction for analysis. in the process, detrital dolomite, an important constituent of arctic ocean sediment, was dissolved away. by comparing grain size spectra obtained with a mastersizer 2000 particle size analyser (malvern instruments, malvern, uk) before and after acid–base treatment, we infer that the detrital dolomite lost in dissolution was mostly in the fine clay size class (fig. 3). although grain size analysis was performed on the <45-mmdiameter class for the untreated samples, and on the <63-mm-diameter class for treated samples, duplicate measurements on the <63-mm-diameter class for the untreated samples demonstrated no change in grain size spectra between the <63-mmand <45-mm-diameter classes, indicating any changes between the untreated and the treated samples were the result of the acid–base treatment. a comparison of the median grain diameter of the untreated and acid–base-treated samples allows us to calculate the relative quantity of detrital dolomite lost during treatment. this provides a means of estimating the carbonate content of the sediment, which could not be directly measured by dsr alone. this estimate is corroborated by elemental ca, measured by x-ray fluorescence (xrf) using the kent state university innov-x alpha series handheld xrf analyser on the untreated core surface. because foraminiferal calcite is minimal, elemental ca predominantly represents detrital carbonate content (polyak et al. 2009). bulk ca peaks consistently at the core depths with calculated dolomite loss, verifying that the acid treatment successfully isolates the terrigenous component, with the majority of sediment alteration limited to the dissolution of the dolomite constituent (fig. 4). it appears that the maximum detrital dolomite content occurred during glacial–deglacial periods, again consistent with the record of elemental ca and various arctic ocean sediment records from the literature (e.g., darby et al. 1989; bischof et al. 1996; phillips & grantz 2001; polyak et al. 2004; polyak et al. 2009). fig. 3 grain size spectra comparison for a sample at 331 cm depth showing the difference in spectra between the untreated sample and acid–base-treated sample residue, which has had any carbonate and biosilica removed. note the decreased volume percentage of grain sizes smaller than 10 mm in diameter and the shift in median grain size towards coarser grains for the acid–base-treated samples. sample 331 was chosen for its initially high elemental ca content and thus maximum potential for dissolution during acid–base treatment. clay mineral cycles from the northwind ridge l.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd180 following acid–base treatment, dsr was measured on the filtered and dried residues using a labspec pro fr ultraviolet/visible/near-infrared (350–2500 nm) spectrophotometer (analytical spectral devices, boulder, co, usa), hereafter referred to as the labspec pro. the full spectra reflectance patterns were used as an estimate of mineral composition, based on a comparison of absorbance/reflectance features of the sample with a mineral standard. this method can present challenges, particularly when working with mineral assemblages, as the presence of some minerals can mask the features of others. as a more quantitative means of estimating mineral composition, we used r-mode factor analysis with varimax rotation, which davis (1986: 548) also calls a “principal component analysis approach to factor analysis”. this is a statistical sorting and data reduction method on the visible (400–700 nm) portion of the labspec pro data, to determine the major factors responsible for variation in the data set. this method has been shown to successfully identify major mineral assemblages, including clay minerals, by comparison with quantitative x-ray diffraction (qxrd) on the northern alaskan margin (ortiz et al. 2009) (fig. 1), and by comparison of results from a large number of atlantic ocean cores with known sediment composition and general mineralogical distributions (e.g., balsam & deaton 1991). in this method, eigenvalues and eigenvectors are extracted from a standardized variance–covariance, or correlation, matrix. then, the eigenvectors, which are calculated in normalized form, are transformed to factors, which are weighted proportionally with the level of total variance they represent. varimax rotation works to maximize the level of variance explained by the leading factors, by repositioning the factor axes so that the loadings are either near �1 or near the origin. initial and post-rotation eigenvalues and variances explained are listed in table 1. the significant factors were retained if their initial eigenvalues were >1 (indicating that they explain more of the variance than the original standardized variables) and could be distinguished from the “noise floor” on the scree plot (fig. 5) see davis (1986) for details on r-mode factor analysis. the factor loadings for the leading factors (table 2), which represent the relative importance of each variable (in this case wavelength) within the factor, were compared against a library of centre-weighted derivatives of clay mineral spectra for interpretation (clark et al. 2003). centre-weighted derivatives, used in order to minimize the truncation or round-off error, are calculated by the symmetrized form of the derivative equation (press et al. 1992): fig. 4 calculated estimate of detrital dolomite lost during acid–base treatment plotted against the bulk elemental ca abundance, measured by x-ray fluorescence. the relative dolomite loss is calculated from the difference in median grain size between acid–base-treated samples and untreated whole-core samples. it is then converted to units of percentage of maximum loss by dividing by the maximum median grain size difference and multiplying by 100. note that 100% does not signify 100% carbonate, but rather the sample with the greatest inferred loss of dolomite. because maximal loss occurs synchronously with ca abundance, we can conclude that acid–base treatment successfully separates the siliciclastic terrigenous component of the sediment, with most sediment alteration limited to the detrital dolomite component. note that there may be small discrepancies in depth scale between the two instruments used to measure elemental ca abundance and grain size-based estimates of dolomite loss. clay mineral cycles from the northwind ridgel.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 181 ′ ( ) ≈ +( ) − −( )[ ]f x f x h f x h h2 visible spectra are typically featureless and can be highly correlated, making it difficult to use them for mineral identification. by taking the first derivative of the spectra, we emphasize the variation or changes in slope of the spectra, making interpretation much easier (balsam & deaton 1991). balsam & deaton (1991) showed that first-derivative curves were consistent between samples of similar mineralogy, and that the peaks are a function of the concentration of the minerals present. they also indicate that the relationship between the relative proportion of a mineral in the sample and the first-derivative spectral peaks may not be direct, making it difficult to make judgments on the percentage composition. following analysis of the factor loadings, the downcore factor scores (table 3), which represent the relative variance contributed by each factor, were plotted versus the elemental content of manganese measured by xrf of the whole core. manganese (mn) has been shown as an indicator for glacial–interglacial cycles in the arctic ocean (jakobsson et al. 2000; polyak et al. 2004; löwemark et al. 2008). high mn content in arctic sediments has been associated with interglacial/interstadial periods, during which either the increased ventilation of deep water promotes mn precipitation, or mn is delivered extensively by siberian river run-off (phillips & grantz 1997; jakobsson et al. 2000; löwemark et al. 2008). the xrf-derived mn variations in our samples are considered in the stratigraphic context of multi-proxy correlations between sediment cores across the western arctic ocean (polyak et al. 2009). the terms “glacial” and “interglacial” in this work should be taken to mean “glacial-type” and “interglacialtype,” respectively, as described in adler et al. (2009), indicating that the cycles observed in the arctic do not necessarily represent full glacial–interglacial amplitudes globally. it is not fully understood why glacial–interglacial conditions are more strongly expressed in the arctic than in other parts of the world, but it may be because of sea-iceand snow albedo-related amplifications of precessional forcing (adler et al. 2009, and references therein). although the magnitude of the glacial cycles may vary, the associated changes in sea level, ice extent and circulation have a major impact on sedimentation in the arctic ocean. table 1 eigenvalues and percentage variance for the leading factors extracted by r-mode factor analysis, before and after varimax rotation. factor initial eigenvalues eigenvalues after rotation eigenvalue % of variance cumulative % eigenvalue % of variance cumulative % 1 20.80 67.09 67.09 16.29 52.55 52.55 2 7.25 23.38 90.48 7.66 24.72 77.27 3 1.59 5.13 95.61 5.69 18.34 95.61 fig. 5 scree plot showing the initial percentage of variance explained by each factor. the leading three factors can be easily distinguished from the “noise floor”. clay mineral cycles from the northwind ridge l.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd182 varimax-rotated r-mode factor analysis (hereafter, vrfa) was also conducted on the bulk dsr measurements from the whole core, and from discrete samples, prior to acid–base treatment. these additional data sets provide a means of comparison between the whole-core data and discrete samples, as well as between untreated samples and acid–base-treated residues. factor loadings and factor scores were compared among the three data sets to verify consistency, and to evaluate the effectiveness of the acid–base treatment. results from the raw dsr data on both the untreated whole core and discrete sediment samples, the colorimetric indices l* (sediment brightness), a* (red–green contrast) and b* (blue–yellow contrast) were obtained and plotted together for comparison (fig. 6). however, because the spectral range for each index is too expansive to provide information on individual mineral composition, their primary use is for stratigraphic purposes. thus, in order to extract information regarding sediment mineralogy, vrfa was employed on the 10-nm resolution dsr data, described below. the ultraviolet/ visible/near-infrared reflectance data on the acid– base-treated samples were compared against mineral reflectance standards following vrfa of the visible portion of the spectra. the estimates of mineral composition based on comparison of absorbance/reflectance features across the 350–2500 nm wavelength spectra were consistent with the mineral assemblages extracted by vrfa. vrfa was conducted on the 400–700 nm wavelength portion of the acid–base-treated dsr data to maintain consistency with the visible data obtained on the untreated whole core and discrete samples. in each data set, vrfa extracted three significant factors responsible for the down-core variations in dsr. significant factors table 2 factor loadings for the leading factors extracted by r-mode factor analysis. communalities are the sum of the squared factor loadings for each variable (wavelength). they represent the percentage variance that the leading factors explain for each variable. wavelength (nm) factor loading 1 factor loading 2 factor loading 3 communality 400 -0.778 0.106 0.536 0.903 410 -0.789 0.152 0.563 0.961 420 -0.792 0.236 0.543 0.978 430 -0.792 0.325 0.497 0.980 440 -0.751 0.362 0.540 0.987 450 -0.653 0.265 0.701 0.988 460 -0.440 0.153 0.852 0.943 470 -0.249 0.274 0.896 0.939 480 -0.301 0.595 0.733 0.982 490 -0.357 0.792 0.448 0.956 500 -0.374 0.824 0.340 0.934 510 -0.375 0.819 0.343 0.929 520 -0.351 0.812 0.373 0.923 530 -0.263 0.854 0.357 0.927 540 -0.014 0.970 0.177 0.973 550 0.256 0.948 -0.059 0.967 560 0.460 0.807 -0.209 0.907 570 0.647 0.631 -0.301 0.907 580 0.795 0.454 -0.323 0.943 590 0.892 0.285 -0.307 0.970 600 0.941 0.146 -0.269 0.980 610 0.962 0.047 -0.229 0.981 620 0.970 -0.024 -0.201 0.983 630 0.973 -0.083 -0.177 0.986 640 0.973 -0.132 -0.160 0.989 650 0.967 -0.174 -0.156 0.989 660 0.958 -0.200 -0.170 0.986 670 0.942 -0.217 -0.203 0.975 680 0.911 -0.217 -0.261 0.945 690 0.878 -0.180 -0.332 0.913 700 0.872 -0.159 -0.359 0.915 clay mineral cycles from the northwind ridgel.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 183 were defined as those with eigenvalues greater than one, and with a percentage variance that could be distinguished from the noise floor in the scree plot (fig. 5). here, we compare the vrfa of the whole-core dsr with that of the acid-base treated samples. vrfa of a subset of the untreated discrete samples from the same depth interval as the acid–base-treated samples yielded very similar results to the vrfa of the whole-core dsr, suggesting no real differences arise from a decrease in sample size. this allows us to infer that any differences between the wholecore data and treated samples are the result of the acid– base treatment. comparison of the factor loadings from the vrfa for the whole-core data and the acid–base-treated samples are shown in fig. 7. the major difference between the two is a redistribution of variance between factors 1 and 2. that is, the loadings for factor 1 of the treated samples are comparable with the loadings for factor 2 of the untreated whole core, and vice versa. factor 3 has a very similar shape for each, but is inverted in the untreated whole core relative to the acid–base-treated samples. because the functions extracted by vrfa are orthogonal, a redistribution of the variance could result in a difference in the rotation or order of the factors extracted. the loadings can also be dependent on the number of factors extracted and rotated (davis 1986). minor differences between untreated and treated factor loadings include stronger loadings for untreated factors 1 and 2 between ca. 400 and 540 nm, whereas untreated factor 3 has slightly weaker loadings, except for a peak at ca. 470 nm. untreated factor 3 also has weaker loadings than treated factor 3 at ca. 580 nm. untreated factors 1 and 3 have stronger loadings between ca. 650 and 700 nm, whereas untreated factor 2 has weaker loadings in this interval. these differences may arise from the dissolution of clay-sized carbonate (as interpreted from the grain-size data), such as dolomite, during acid–base treatment, unmasking the reflectance properties of less abundant clays, and thus amplifying their signals. the slight redistributions in variance between factors may have contributed to the offsets as well. using a correlation matrix, the vrfa factor loadings for the acid–base-treated samples were compared with symmetric first-derivative transformations of a library of silt and clay mineral dsr signatures provided by the us geological survey (clark et al. 2003) and the kent state university (ksu) spectral library (as used in ortiz et al. [2009]). factor 1 correlated with the reflectance signature of a smectite + chlorite clay assemblage, with a correlation fit of r = -0.98 (fig. 8a). the first-derivative smectite + chlorite spectrum was derived from the spectral standard for a mixture of these minerals provided by the us geological survey spectral library version 5 (clark table 3 factor scores for the leading factors extracted by r-mode factor analysis. depth (cm) factor 1 scores factor 2 scores factor 3 scores 202 -0.861 -0.076 0.289 206 -1.021 -0.111 1.213 210 -1.029 -0.637 1.135 214 -1.448 -1.328 1.323 218 -1.319 -1.050 0.982 222 -1.396 -1.226 0.816 226 -0.962 -0.572 0.964 230 -1.280 -0.597 0.850 234 -1.466 -0.738 0.133 238 -0.921 -0.120 -0.930 242 -1.453 -0.873 -0.234 249 -1.027 -0.695 0.073 253 -0.634 0.845 -0.140 257 -0.542 1.400 -0.527 261 -0.605 0.748 0.296 265 -0.836 -0.767 -1.572 269 -0.739 1.617 -0.482 273 -0.429 1.414 -0.555 277 -0.470 1.440 -0.627 281 -0.730 0.254 -0.075 285 -0.371 0.118 0.096 289 0.617 -2.606 -1.783 293 1.165 -0.884 -0.255 297 0.592 -2.310 -1.800 301 0.944 -0.100 0.108 305 0.587 0.280 -0.749 309 0.815 0.618 0.329 313 0.173 0.121 -0.417 315 -1.083 -0.885 -1.498 317 0.068 -0.176 0.403 321 -0.659 -0.497 0.270 325 -0.082 -0.748 0.073 327 -0.359 -0.188 -0.908 329 -0.281 0.120 -0.790 331 -1.386 -0.315 -1.351 333 -0.292 0.050 0.684 337.2 -0.483 -0.886 0.069 341 -0.613 -0.299 2.416 345 0.187 2.189 0.271 349 1.138 0.030 0.511 353 1.588 0.079 0.856 357 1.202 -2.163 -1.508 361 1.834 0.084 0.504 365 1.188 0.244 0.347 369 -0.311 0.388 -1.066 373 -0.356 0.399 -1.593 377 -1.102 -0.753 2.205 381 -0.480 -0.574 0.540 385.5 -0.523 1.322 0.069 389 -0.076 0.939 0.331 393 1.497 -0.357 -0.028 400 2.208 -1.835 -0.766 404 2.398 -0.712 0.442 408 1.685 0.158 0.592 412 0.350 1.003 0.524 416 -0.191 0.422 0.521 420 0.370 1.773 0.730 424 -0.471 1.354 -1.461 428 0.098 0.743 0.391 432 1.554 -0.473 -0.213 434 1.682 0.386 0.937 436 1.310 0.947 1.212 438 0.736 0.847 0.373 440 0.206 0.634 -1.653 442 0.396 1.116 0.371 444 -0.024 0.341 0.823 446 0.532 0.075 -0.613 448 0.162 0.054 0.419 452 0.108 0.624 0.443 456 -0.884 1.831 0.423 460.2 -0.635 1.574 -1.449 464 -0.811 1.182 -2.521 468 -0.854 -1.853 0.024 472 -0.896 -1.677 2.814 476.2 1.620 -0.780 -0.144 478 1.724 -0.677 -0.144 480 1.263 0.690 0.669 482 1.167 0.676 0.202 486 -0.772 -0.592 -2.213 clay mineral cycles from the northwind ridge l.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd184 et al. 2003). factor 2 correlated with the illite + goethite signature, with r = 0.90 (fig. 8b). the first-derivative illite + goethite standard (ksu spectral library, as used in ortiz et al. [2009]) was calculated as a 50/50 numerical average of the spectra for the minerals illite and goethite, which were verified by xrd at ksu (carlson, pers. comm. 2009). factor 3 correlated with the signature for glauconite, with r = 0.97 (fig. 8c). the glauconite signature was determined by a first-derivative transformation of the spectral standard measured by the labspec pro at ksu for a known glauconite sample, which was corroborated by comparison of the raw reflectance curve with that provided for glauconite by the us geological survey spectral library version 5 (clark et al. 2003). these three factors, smectite + chlorite (52.5%), illite + goethite (24.7%) and glauconite (18.3%), are responsible for 95.5% of the total variation (table 1). when plotted against the mn proxy for glacial–interglacial cycles, factor 1, hereafter smectite + chlorite, varied directly with elemental mn content, peaking synchronously with mn (fig. 9a), and factor 2, hereafter illite + goethite, varied inversely with mn content, peaking during low mn (fig. 9b). factor 3, hereafter glauconite, demonstrated a higher frequency of variability, more indicative of millennial rather than glacial–interglacial time scales. however, the maximum glauconite scores appear to occur mostly during periods of low mn, or during transitions between low and high mn levels (fig. 9c). fig. 6 colorimetric indices l* (sediment brightness; top), a* (red–green contrast; middle) and b* (blue–yellow contrast; bottom) for the whole-core surface and the discrete samples. fig. 7 diffuse spectral reflectance (dsr) varimax-rotated r-mode factor analysis (vrfa) factor loadings for the acid–base-treated samples, plotted with the vrfa factor loadings for the untreated whole-core dsr. treated factor 1 (black line with filled squares) corresponds to untreated factor 2 (black line with open squares). treated factor 2 (darkgrey line with filled circles) corresponds to untreated factor 1 (dark-grey line with open circles). treated factor 3 (light-grey line with filled triangles) corresponds to untreated factor 3 (light-grey line with open triangles). differences between untreated whole-core loadings and treated sample loadings are described in the text. -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 375 425 475 525 575 625 675 725 u n tr e a te d f a ct o r 3 lo a d in g f a ct o r lo a d in g wavelength (nm) p25 treated dsr factor 1 p25 treated dsr factor 2 p25 treated dsr factor 3 p25 whole core untreated dsr factor 1 p25 whole core untreated dsr factor 2 p25 whole core untreated dsr factor 3 clay mineral cycles from the northwind ridgel.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 185 fig. 8 (a) factor 1 spectrum versus smectite + chlorite standard. (b) factor 2 spectrum versus illite + goethite standard. (c) factor 3 spectrum versus glauconite standard. spectral standards provided by clark et al. (2003) and the kent state university spectral library (as used in ortiz et al. [2009]). clay mineral cycles from the northwind ridge l.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd186 fig. 9 (a) down-core variability of factor 1 (smectite + chlorite) plotted against mn proxy for glacial–interglacial cycles: illustrates the importance of smectite + chlorite deposition during interglacials. (b) down-core variability of factor 2 (illite + goethite) plotted against mn proxy for glacial–interglacial cycles: illustrates the importance of illite + goethite deposition during glacials. (c) down-core variability of factor 3 (glauconite) plotted against mn proxy for glacial–interglacial cycles: illustrates the higher frequency variability of glauconite in relation to the glacial– interglacial mn cycles. glauconite deposition is interpreted to be most important during glacial and deglacial intervals. also marked are the marine isotope stage (mis) boundaries, and their associated ages. the dashed line at the mis 3/4 boundary indicates an approximate depth for this boundary. clay mineral cycles from the northwind ridgel.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 187 discussion smectite and chlorite: interglacial minerals from the eastern arctic and bering sea when compared against the mn cycles, the factor score for smectite + chlorite covaries with maximum elemental mn (fig. 9a), which is interpreted to indicate interglacial periods. this is consistent with findings of smectite + chlorite maxima during interglacials in cores from various areas of the arctic ocean, including the northwind, mendeleev, alpha and lomonosov ridges (ortiz et al. 2006; ortiz et al. 2007). we propose several possible explanations for this distribution. first, the major sediment source regions for both smectite and chlorite to the arctic ocean were largely cut-off during glacial periods. for example, the bering sea is known as an important chlorite province and a likely source area for chlorite north of the bering strait (kalinenko 2001). smectite may also have been present in the bering strait region as continental run-off from volcanic rocks of eastern siberia and southern alaska (naidu & mowatt 1983; viscosi-shirley, mammone et al. 2003; darby & bischof 2004). however, the bering sea source operated only during interglacials and major interstadials, as the bering strait (50 m deep) was subaerially exposed at low sea levels. alternatively, chlorite, as well as major smectite sources, exists along the siberian arctic margins. according to viscosi-shirley, mammone et al. (2003), chlorite can be found in the east siberian and chukchi seas (although a specific source is not discussed). dethleff et al. (2000) also note that the suspended particulate material of the yana river is enriched in chlorite. finally, it is well established that smectite is prevalent in the western laptev and kara seas (kalinenko 2001; winkler et al. 2002; viscosi-shirley, mammone et al. 2003; vogt & knies 2008). a volcanically derived clay mineral, smectite is sourced primarily from the mesozoic siberian trap basalts of the putorana mountains, from where it is drained by north-flowing rivers, mostly by the yenisey river drainage system. during pleistocene glacial maxima, large ice sheets blocked the rivers, preventing the riverine transport of sediments from the putorana to the laptev and kara seas (mangerud et al. 2004; svendsen et al. 2004; vogt & knies 2008). because smectite + chlorite maxima occur in p25 in all interglacial intervals, including periods of low sea level, we believe that these minerals are primarily related to siberian rather than pacific provenance, which is consistent with the major source of mn (hölemann et al. 1999). nevertheless, smectite and/or chlorite may also have been redeposited to the study area during sea level falls from the chukchi shelf. delivery of smectite and chlorite to the p25 site during interglacial periods could occur by two potential processes: ocean currents or sea-ice rafting. according to viscosi-shirley, pisias et al. (2003), sediments derived from eastern siberia and from the bering sea inflow are prevalent in the modern chukchi sea, where there is significant sediment transport via water circulation. finegrained silts and clays, which certainly include chlorite and smectite, can be suspended and transported by chukchi shelf current velocities (mcmanus et al. 1969). northward-flowing currents dominate all water depths, and are directed through a number of submarine valleys, which exit into the southern canada basin (viscosishirley, pisias et al. 2003; darby & bischof 2004). pickart (2004) also described the “beaufort shelfbreak jet” as part of the alaskan coastal current, which is an eastwardflowing current that carries chukchi waters to the basin. in addition, pacific waters that flow into the chukchi sea become cooler and saltier during sea-ice formation, and form descending plumes that penetrate deep into the canada basin (jones 2001; williams et al. 2008). this could provide a mechanism for transport of chlorite and smectite to the northwind ridge. also, smectite delivery could occur via the subsurface atlantic layer circulation, from as far as the kara sea, because smectite-rich silts and clays brought in via rivers can become incorporated into surface and intermediate waters (vogt & knies 2008). this water is carried eastward along the siberian margin, and then enters the subsurface circulation that extends to all arctic ocean basins, including the southern canada basin (jones 2001; rudels et al. 2004) (fig. 1). in the fram strait region, the clay fraction has been shown to be transported over significant distances as a suspended load, possibly even bringing smectite from as far as the iceland–faeroe ridge (winkler et al. 2002; vogt & knies 2009). however, it is unlikely that this smectite could reach the much further away canada basin, because this would require some type of autosuspension in order to prevent these clays from settling over such distances, a process that is unlikely to occur in weak currents such as the atlantic intermediate current. most smectite-enriched sediments in the arctic ocean are more likely to be sourced from the western laptev and kara seas (vogt & knies 2009). the other important process for the transport of sediment to the arctic ocean is sea-ice rafting. there is significant evidence that smectite-rich sediment is transported via sea ice from the shelves of the laptev and kara seas (dethleff et al. 2000; winkler et al. 2002; vogt & knies 2008). fe grain matching has shown siberian sediments in pleistocene cores from the western arctic, providing evidence of a circulation pattern that brings sea ice from the laptev and kara seas into the bg on a clay mineral cycles from the northwind ridge l.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd188 regular basis (darby & bischof 2004; darby et al. 2006). also, sampling of dirty ice has revealed siberian sediments from the laptev and kara seas in modern ice floes in the bg (darby 2003; darby et al. 2006). the transport of these modern ice floes to the canada basin is attributed to a change in circulation patterns caused by a shift in the ao, which will be discussed in detail later. illite and goethite: glacial/deglacial pulses from north-western canada the factor score for illite + goethite demonstrates an inverse correlation with mn content, reaching maxima during glacial periods (fig. 9b). this pattern is consistent with results by ortiz and coworkers (ortiz et al. 2006; ortiz et al. 2007), in which peaks of illite in cores from across the central arctic ocean coincide with inferred glacial maxima, whereas goethite seems to co-occur with glacial to interglacial transitions. although illite is the most common clay mineral in arctic shelf sediments, and is very abundant in both the chukchi and beaufort seas (naidu & mowatt 1983; kalinenko 2001), in the central arctic ocean, it seems to be particularly abundant during glacial periods (ortiz et al. 2006; ortiz et al. 2007). this pattern is probably, at least partly, the result of diminished deposition of other types of clays (smectite and chlorite) at these times, as a result of different transportation pathways and/or source areas and processes during glacials and interglacials. during glacial events, the arctic was a very different environment. the ocean itself was reduced in size by as much as 50% because of the low glacial sea level, and shallow arctic shelves were either subaerially exposed or covered by ice sheets, which existed around much of the periphery of the arctic ocean (darby et al. 2006, and references therein). this also meant a limited connection with the rest of the world’s oceans and complete isolation from the pacific. there were also, presumably, greater expanses of thick sea-ice coverage or even ice shelves over large parts of the central arctic ocean (phillips & grantz 2001; darby et al. 2006; bradley & england 2008; jakobsson, polyak et al. 2008). in contrast, during deglaciations and ice-sheet surging events, the arctic ocean hosted armadas of icebergs, which played a major role in sediment transport and deposition (darby & zimmerman 2008). all of these factors contribute to drastically altered sedimentation regimes in comparison with modern-type, interglacial environments. so, there are a number of reasons why the source of sediment to the canada basin might be predominantly from north american provenance during glacials, including thick pack ice covering large portions of the central arctic ocean (phillips & grantz 2001; darby et al. 2006), possible changes to the general arctic circulation patterns (darby & bischof 2004; darby et al. 2006) and a voluminous discharge from the laurentide ice sheet (bigg & wadley 2001; darby et al. 2002; darby & zimmerman 2008). in modern environments, north-western canada, particularly the shelf off banks island, is the primary source region for ice-rafted sediment deposited on the northwind ridge, especially during times when circulation promotes an enhanced bg (darby & bischof 2004; darby et al. 2006). this sediment has a large component of till that was deposited during the laurentide ice-sheet expansions (bischof et al. 1996). illite is also common along the shorelines and within sediments off the mackenzie river delta (kalinenko 2001), derived to a considerable extent from glacial or periglacial deposits. such deposits are a likely source of illite as this clay mineral is commonly formed by fragmentation of micas during mechanical weathering, although it may also be derived from hydrolysis of smectite (deconinck et al. 2001). during glaciations, the flux of glacially eroded material to the canada basin was obviously much higher than at present, which may have raised the content of illite in the clay mineral fraction. for a comparison, a large peak in illite concentration in the eurasian basin sediments was related to a pronounced pulse of meltwater and iceberg discharge from the collapsing saalian ice sheets (knies & vogt 2003). similar events were common for the northern margin of the laurentide ice sheet, as evidenced by stable-isotope and ice-rafteddetritus records across the western arctic ocean (poore et al. 1999; darby et al. 2006; polyak et al. 2007; polyak et al. 2009; darby & zimmerman 2008). goethite is not commonly studied in arctic sediments, and we cannot conclude on its origin in sediment cores from the northwind ridge, as well as other sites from the central arctic ocean, at this time. goethite has been documented in soils of northern alaska (hill & tedrow 1961), and has been described as a product of basalt weathering in greenland (mørup et al. 1990). it can also form diagenetically in marine sediments, and may even be the dominant diagenetic precipitate in these environments (van der zee et al. 2003). the identification of goethite peaks at the glacial–interglacial transitions in arctic sediment cores (ortiz et al. 2006; ortiz et al. 2007) suggests that goethite was likely related to discharge of meltwater and icebergs during ice-sheet collapses, but the provenance is not yet fully understood. glauconite: deglacial input from the north slope of alaska? glauconite forms by the diagenetic alteration of biotite and other clays in low-oxygen marine environments, but clay mineral cycles from the northwind ridgel.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 189 can also be detrital (grim 1968). its presence in arctic sediment is not well established, partly because it produces many of the same diffraction peaks as illite for oriented clay mineral x-ray diffraction analysis (moore & reynolds 1997). its presence here is inferred from the comparison of the reflectance signature in the visible and near-infrared of this mineral in standards and samples from core p25. analysis of the down-core scores for glauconite indicates that this mineral has a higher frequency variability than the glacial–interglacial cycles defined by mn (fig. 9c). when plotted against the factor scores for smectite + chlorite and illite + goethite, it appears that glauconite reaches maxima on transitions between the other two factors, namely, after illite + goethite. occasionally, it seems to follow illite + goethite somewhat more closely. we thus propose that glauconite deposition is most significant during late glacial or deglacial periods. because of the apparently limited distribution of glauconite in arctic marine sediment, we infer that it has a relatively proximal provenance. a potential local source of glauconite is the north slope of alaska (fig. 10). at least two glauconite-bearing source rocks are known from the north slope, the triassic shublik formation (parrish et al. 2001) and the lower cretaceous kemik sandstone (macquaker et al. 1999). studies of modern dirty ice samples have indicated that the alaskan nearshore is not a significant source of sediment to the ice in this region at present (darby 2003), but this may not have been the case in the past when the sea level was lower. several studies have indicated northern alaska as a potential source region for sediments on the beaufort shelf (naidu et al. 1971; rodeick 1979; reimnitz et al. 1993). darby (1975) indicated mesozoic sedimentary rocks from the north slope as the source of kaolinite clay in central arctic samples. this evidence suggests that the mesozoic glauconite source rocks from this region could have provided glauconite-rich sediment to the beaufort shelf, and ultimately to the p25 site. alternatively, the glauconite in p25 may be related to dolostone clasts, which were found to contain glauconite in cores from the beaufort sea and northwind ridge (phillips & grantz 1997, 2001). many studies indicate the north-western canadian arctic archipelago as the most likely provenance region for dolostone clasts, which form distinct layers in glacial and deglacial intervals in sediment cores from the western arctic ocean (darby 1975; bischof et al. 1996; phillips & grantz 2001). unlike the first two vrfa factors, glauconite was not observed in the dsr study of sediment cores from the central arctic ocean (ortiz et al. 2006; ortiz et al. 2007), which included p25 as a small fraction of the total samples analysed. it is quite possible that glauconite is present in these cores, but was missed because the presence of dolomite and/or organics partially masked its reflectance signature. alternatively, the relatively low abundance of this mineral phase, which should be concentrated in marginal marine sediment, may not have been great enough in abundance to be included in the leading factors. the dissolution of dolomite and concentration of the residual phases present in response to the acid–base treatment applied to our samples most likely explains the detection of glauconite by dsr. this is supported by our comparison of the factor loadings from the untreated whole-core dsr measurements with those from the acid–base-treated samples. the glauconite reflectance/absorbance features are still identifiable in the untreated factor 3, but the overall loadings do not correlate well with glauconite. this results from slightly weaker loadings through a large part of the untreated factor 3 spectrum (ca. 400–625 nm), which may partially result from the stronger absorbance of dolomite through much of this interval, as well as the very strong loadings in the red end of the spectrum (ca. 650–700 nm), possibly pointing to the presence of biogenic opal or certain organics, which can have strong reflectance peaks in that portion of the spectrum (yacobi & gitelson 2000; han 2005). possible causes for circulation and provenance changes as previously discussed, conditions in the arctic ocean and its periphery were very different between glacial and interglacial intervals, profoundly altering the sedimentation regime. during glaciations, any sedimentary input from the bering sea/pacific ocean (smectite and chlorite) was completely blocked by exposure of the bering strait. similarly, large sediment sources to the laptev and kara seas, the ob and yenisy rivers, were dammed by ice sheets (mangerud et al. 2004; svendsen et al. 2004; vogt & knies 2008; polyak et al. 2008). even if occasional surges of river discharge occurred during glacials, providing smectite and chlorite sediments to the siberian seas, large, grounded ice sheets existing over the chukchi borderland (polyak et al. 2001; jakobsson et al. 2005; polyak et al. 2007), including the northwind ridge, would have blocked or impeded sea ice or other means of transport to the location of core p25 on the northwind ridge. however, these large ice floes, likely originating from the north-west portion of the laurentide ice sheet (polyak et al. 2001; jakobsson et al. 2005; polyak et al. 2007), could have easily transported glacially-eroded illite clays from canadian provenance regions (darby & bischof 2004; darby et al. 2006). during the deglaciation, ice sheets began to melt, massive meltwater input via northward-flowing rivers clay mineral cycles from the northwind ridge l.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd190 dumped sediment into the arctic ocean and sea level rise re-established its connection with the pacific. this allowed pacific and siberian sediment sources to again provide smectite and chlorite clay to the marginal seas, where it could potentially be transported to the northwind ridge (darby et al. 2001). if transport occurred via sea ice, the prevailing surface circulation would dominate its dispersion. fig. 10 arctic ocean bathymetric map with extreme states of the arctic oscillation (from darby & bischof 2004), and interpretation of potential sources and transport of p25 sediments. modern locations of the transpolar drift (tpd) and beaufort gyre (bg) are indicated (fig. 1). the approximate location of p25 is indicated by the white star. solid arrows indicate surface circulation during a negative phase of the arctic oscillation (ao-), and dashed arrows indicate surface circulation during its positive phase (ao+). the white dotted arrow indicates a possible circulation of tpd during very positive ao+. white, semi-transparent block arrows indicate interpreted transport pathways of the illite + goethite assemblage from the shelf off banks island and the mackenzie river. glauconite may also be derived from these regions. note that these arrows follow the aocirculation. dark semi-transparent block arrows indicate interpreted transport pathways of the smectite + chlorite assemblage from the putorana mountains and siberian platform to the kara and laptev seas, and from sources in eastern siberia and the bering sea through the bering strait to the chukchi sea. note that these arrows follow the ao+ circulation. the dark semi-transparent dashed arrow indicates possible direct transport to the core site from a vastly shifted tpd during very positive ao+. thin white arrows indicate a possible source and transport of glauconite from northern alaska. (international bathymetric chart of the arctic ocean base map provided by jakobsson, macnab et al. 2008.) clay mineral cycles from the northwind ridgel.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 191 the modern circulation of wind-driven surface currents in the arctic is directly affected by atmospheric pressure gradients, particularly by the ao, which is the leading mode of sea level pressure variability in the northern hemisphere, and which generally operates on monthly to decadal time scales (thompson & wallace 1998; rigor et al. 2002; darby et al. 2006). shifts in the mode of the ao thus influence the patterns of ice movement, as well as the degree and thickness of sea-ice coverage (polyakov & johnson 2000; kwok 2000; rigor et al. 2002; polyakov et al. 2003; serreze et al. 2003; zhang et al. 2003; shimada et al. 2006, darby & bischof, 2004; steele et al. 2008). numerous studies have indicated that a shift in the ao from its negative phase (ao-) to its positive phase (ao+) is associated with the thinning of sea ice in the bg, increased export of thick multiyear ice (largely from the beaufort sea) through the fram strait, and increased sea surface temperature (e.g., rigor et al. 2002; zhang et al. 2003; pfirman et al. 2004; steele et al. 2008). changes similar to those associated with shifts in the ao, if they existed on millennial to glacial–interglacial time scales, could, in part, explain the variations in sedimentation patterns observed in p25. during ao-, the clockwise-rotating bg is relatively strengthened, and the counter-clockwise tpd is positioned closer to the kara and barents sea, transporting ice directly out through the fram strait, and limiting its influence on sedimentation at the northwind ridge. at these times, sediment source regions for the northwind ridge are dominantly northwestern canada, particularly the shelf off banks island, and the mackenzie river (darby & bischof 2004; darby et al. 2006) (fig. 10). sediment-laden ice is transported directly over the core site from these sources by the circulating bg, although thick ice packs may have slowed the ice drift. this is consistent with the illite + goethite and glauconite assemblages that dominate glacial and deglacial periods in p25 (fig. 10). as the ao shifts to a positive vorticity, the tpd moves closer to north america, allowing the bg to capture ice floes originating from siberian seas, and circulate them to the amerasia basin and the northwind ridge (mysak 2001; darby 2003; hakkinen & proshutinsky 2004; darby & bischof 2004; darby et al. 2006) (fig. 10). during especially positive phases of the ao, the tpd may even shift so far towards north america as to transport ice directly over the northwind ridge (darby & bischof 2004) (fig. 10). the tpd only shifts this far to the east during a very positive phase of the ao (above +2) (kwok 2000; rigor et al. 2002; darby & bischof 2004). additionally, it is thought that during ao+, increased export of ice from the bg into the north atlantic possibly enhances the influx of ice drift through the bering strait into the chukchi sea (rigor et al. 2002; darby & bischof 2004; pfirman et al. 2004) (fig. 10), which could potentially raft smectiteand especially chlorite-rich sediment into the southern canada basin during high sea level stands (fig. 10). because a strongly positive ao can deliver both siberian sea and bering strait (southwestern alaska) smectite to the canada basin, this process is consistent with the smectite + chlorite assemblage that dominates interglacial periods in the core (fig. 10). thus, it is possible that the general circulation regimes associated with the negative and positive phases of the ao are also manifested on stadial and interstadial, and potentially glacial and interglacial, timescales, respectively. a more negative ao-like circulation might dominate stadials and glacials, whereas a more positive ao-like circulation may dominate interstadials and interglacials. whether these general patterns of circulation are caused by atmospheric changes associated with shifts in the ao itself remains to be seen. there is some evidence that the ao and ao-like atmospheric pressure variations operate on multiple time scales (wang & ikeda 2000; mysak 2001; polyakov et al. 2003; deser & teng 2008). the ao has a seasonal pattern as well as an annual to decadal pattern (thompson & wallace 1998; thompson & wallace 2000a, b; polyakov et al. 1999; wang & ikeda 2000; rigor et al. 2002; deser & teng 2008). a longer, multi-decadal pattern (shifting every 50–80 years) has been termed the “low-frequency oscillation” or lfo (polyakov et al. 2003). finally, an ao-like circulation pattern operating on centennial to millennial timescales has been suggested by an analysis of the holocene alkenone-derived proxy sea surface temperature records from the north pacific and north atlantic, corroborated with millennial-scale model simulations from a coupled atmosphere–ocean global circulation model (kim et al. 2004). although it is still uncertain whether an ao-like oscillation pattern exists on millennial or longer time scales, ice-rafted fe grains from the laptev sea are found to vary in cores off alaska with a millennial beat (darby & bischof 2004; herman et al. 2006). the drastically different atmospheric and climatic conditions associated with glacial and interglacial periods offer the potential to set up two different modes of atmospheric pressure and wind patterns, and, thus, sea-ice circulation. modelling studies show that during the last glacial maximum, atmospheric pressure gradients and geostrophic wind patterns were dramatically altered by the existence of the north american and eurasian ice sheets (nørgaard-pedersen et al. 2003, and references therein). model simulations also indicate that the icelandic low was either weakened or displaced to the southclay mineral cycles from the northwind ridge l.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd192 east, relative to its modern position, and that the aleutian low was strengthened (toracinta et al. 2002; byrkjedal et al. 2006). in general, sea-level pressure increased over the arctic during the last glacial maximum (byrkjedal et al. 2006). this is consistent with the dominant atmospheric conditions during the negative phase of the ao. aois associated with a high sea level pressure anomaly over the arctic (polyakov & johnson 2000; rigor et al. 2002), as is the negative phase of the north atlantic oscillation (nao), which is generally thought to be a regional representation of the ao (mysak 2001). the negative ao/nao indices are also associated with a weaker icelandic low (kwok 2000; polyakov & johnson 2000; mysak 2001). this imparts a dominantly anticyclonic circulation on the arctic, strengthening the bg and constraining the tpd towards the eastern arctic (proshutinsky & johnson 1997; rigor et al. 2002). in contrast, modern conditions exhibit decreased high pressure over the arctic, a stronger icelandic low and a weaker aleutian low, relative to the last glacial maximum model studies (toracinta et al. 2002; byrkjedal et al. 2006). this is consistent with atmospheric conditions during the positive phase of the ao. that is, an increase in the ao/nao index corresponds to a weakening of the aleutian low (ambaum et al. 2001), an intensification of the icelandic low (kwok & rothrock 1999; kwok 2000; polyakov & johnson 2000) and a general decrease in arctic high pressure (polyakov & johnson 2000; rigor et al. 2002). this sets up the dominantly cyclonic circulation in the arctic, which creates a weaker bg and a tpd that is shifted closer to north america (proshutinsky & johnson 1997; kwok 2000; rigor et al. 2002). consequently, if during glacial periods atmospheric conditions are similar to those predicted by the last glacial maximum models, they might create negative ao-like conditions, tending to promote anticyclonic circulation in the arctic. similarly, interglacial periods might have atmospheric conditions that promote cyclonic circulation, causing a tendency for the tpd to shift towards north america more often, or for longer periods of time. the sediment provenance and transport pathways presumably associated with these circulation patterns are consistent with the cyclic sedimentation regimes observed in our data for glacial–interglacial periods. conclusions the variations in clay mineralogy in core p25 from the northwind ridge have demonstrated alternating sediment provenance depending on glacial–interglacial cycles. it is inferred that the predominant clay minerals during interglacial intervals, smectite and chlorite, are transported to the core site by currents and/or sea ice from northern siberia, and from the bering sea. during glacial intervals, the predominant deposition of illite and goethite is presumably related to sediment discharged from the laurentide ice sheet. a relatively strong bg circulation might have enhanced the transportation of this sediment to the p25 site, although the process may have been slowed by thick ice conditions. the glauconite variability is possibly associated with sediments from the north slope of alaska during deglacial events or with dolomite-rich sediments, which are characteristic of laurentide iceberg-discharge pulses. factors such as terrestrial ice sheets, sea-ice extent and sea level have a great impact on glacial–interglacial sedimentation, and are likely the primary reasons for the observed sedimentation patterns in p25. also, these sediment cycles, as well as modelling studies, are consistent with the hypothesis of a glacial–interglacial atmospheric variability that sets up alternating sea surface circulation patterns—similar to how the ao operates on shorter time scales today. with similar studies of other cores, it may become possible to piece together a confident understanding of the shifting sedimentation and circulation patterns, and their forcing, on these time scales. acknowledgements we thank the captain and crew of the icebreaker uscgc healy. we thank m. torresan of the us geological survey, menlo park, ca, usa, for assisting with our access to the p25 core. this study was supported by funds from the us national science foundation’s office of polar programs (grants arc-0612384 to jdo; arc-0612473 to lp; and arc-0612493 and odp-0525881 to dad), and by grants from the kent state university research council to jdo. renee crane and bethany lavins assisted with sample preparation. this manuscript is based on lny’s senior honors thesis while she was at the department of geology, kent state university. we would also like to thank the kent state university honors college and the senior honors thesis sponsors of lny, hugh and jean stewart and barbara dickerson, for their support in conjunction with this project. two anonymous reviewers provided useful comments and suggestions that helped to improve the manuscript. references aagaard k. 1984. the beaufort undercurrent. in p.w. barnes et al. (eds.): the alaskan beaufort sea: ecosystems and environments. pp. 47–71. new york: academic press. aagaard k., swift j.h. & carmack e.c. 1985. thermohaline circulation in the arctic mediterranean seas. journal of geophysical research—oceans 90, 4833–4846. clay mineral cycles from the northwind ridgel.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 193 adler r., polyak l., ortiz j., kaufman d., channell j.e.t., xuan c., fornaciari e., grottoli a. & sellen e. 2009. sediment record from the western arctic ocean with an improved late quaternary age resolution: hotrax core hly0503-8jpc, mendeleev ridge. global and planetary change 68, 18–29. ambaum m.h.p., hoskins b.j. & stephenson d.b. 2001. arctic oscillation or north atlantic oscillation? journal of climate 14, 3495–3507. arctic summer west scientific party 1993. cruise to the chukchi borderland, arctic ocean. eos, transactions of the american geophysical union 74, 253–254. balsam w.l. & deaton b.c. 1991. sediment dispersal in the atlantic ocean: evaluation by visible light spectra. reviews in aquatic sciences 4, 411–447. bigg g.r. & wadley m.r. 2001. the origin and flux of icebergs released into the last glacial maximum northern hemisphere oceans: the impact of ice sheet topography. journal of quaternary science 16, 565–573. bischof j., clark d. & vincent j. 1996. pleistocene palaeoceanography of the central arctic ocean: the sources of ice rafted debris and the compressed sedimentary record. palaeoceanography 11, 743–756. bischof j.a. & darby d.a. 1997. mid to late pleistocene ice drift in the western arctic ocean: evidence for a different circulation in the past. science 277, 74–78. bradley r.s. & england j.h. 2008. the younger dryas and the sea of ancient ice. quaternary research 70, 1–10. byrkjedal o., kvamsto n.g., meland m. & jansen e. 2006. sensitivity of last glacial maximum climate to sea ice conditions in the nordic seas. climate dynamics 26, 473–487. campbell j.s. & clark d.l. 1977. pleistocene turbidites of the canada abyssal plain of the arctic ocean. journal of sedimentary petrology 47, 657–670. clark d.l., whitman r.r., morgan k.a. & mackay s.d. 1980. stratigraphy and glacio marine sediments of the amerasian basin, central arctic ocean. geological society of america special paper 181. boulder, co: geological society of america. clark r.n., swayze g.a., wise r., livo k.e., hoefen t.m., kokaly r.f. & sutley s.j. 2003. usgs digital spectral library splib05a. usgs open-file report 03-395. denver, co: us geological survey. colony r. & thorndike a.s. 1984. an estimate of the mean field of arctic sea ice motion. journal of geophysical research—oceans 89, 10 623–10 629. comiso j.c., parkinson c.l., gersten r. & stock l. 2008. accelerated decline in the arctic sea ice cover. geophysical research letters 35, l01703, doi: 10.1029/2007gl031972. curry r. & mauritzen c. 2005. dilution of the northern north atlantic ocean in recent decades. science 308, 1772–1774. dalrymple r.w. & maass o.c. 1987. clay mineralogy of late cenozoic sediments in the cesar cores, alpha ridge, central arctic ocean. canadian journal of earth sciences 24, 1562–1569. darby d.a. 1975. kaolinite and other clay minerals in arctic ocean sediments. journal of sedimentary petrology 45, 272–279. darby d.a. 2003. sources of sediment found in sea ice from the western arctic ocean, new insights into processes of entrainment and drift patterns. journal of geophysical research—oceans 108, 3275. darby d.a. & bischof j.f. 2004. a holocene record of changing arctic ocean ice drift analogous to the effects of the arctic oscillation. palaeoceanography 19(1), article no. pa1027. darby d., bischof j., cutter g., de vernal a., hillaire-marcel c., dwyer g., mcmanus j., osterman l., polyak l. & poore r. 2001. new record of pronounced changes in arctic ocean circulation and climate. eos, transactions of the american geophysical union 82, 603–607. darby d.a., bischof j., spielhagen r., marshall s. & herman s. 2002. arctic ice export events and their potential impact on global climate during the late pleistocene. paleoceanography 17(2), 15.1–15.17. darby d.a., naidu a.s., mowatt t.c. & jones g. 1989. sediment composition and sedimentary processes in the arctic ocean. in y. herman (ed.): the arctic seas— climatology, oceanography, geology, and biology. pp. 657–720. new york: van nostrand reinhold. darby d.a., polyak l. & bauch h. 2006. past glacial and interglacial conditions in the arctic ocean and marginal seas—a review. progress in oceanography 71, 129–144. darby d.a. & zimmerman p. 2008. ice-rafted detritus events in the arctic during the last glacial interval and the timing of the innuitian and laurentide ice sheet calving events. polar research 27, 114–127. davis j.c. 1986. statistics and data analysis in geology. 2nd edn. new york: john wiley & sons. deconinck j.-f., gillot p.-y., steinberg m. & strasser a. 2001. syn-depositional, low temperature illite formation at the jurassic–cretaceous boundary (purbeckian) in the jura mountains (switzerland and france); k/ar and delta 18o evidence. bulletin de la societe geologique de france 172, 343–348. deser c. & teng h. 2008. evolution of arctic sea ice concentration trends and the role of atmospheric circulation forcing, 1979–2007. geophysical research letters 35, l02504, doi: 10.1029/2007gl032023. dethleff d., rachold v., tintelnot m. & antonow m. 2000. sea-ice transport of riverine particles from the laptev sea to fram strait based on clay mineral studies. international journal of earth sciences 89, 496–502. grim r.e. 1968. clay mineralogy. 2nd edn. new york: mcgraw hill. herman s., darby d.a., cook m.s. & keigwin l.d. 2006. the century-scale history of the arctic oscillation based on detrital fe grain provenance of russian sea ice origins in the arctic off alaska. eos, transactions of the american geophysical union 87, fall meeting supplement, abstract os52b-06 mcs 310. clay mineral cycles from the northwind ridge l.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd194 hakkinen s. & proshutinsky a. 2004. freshwater content variability in the arctic ocean. journal of geophysical research—oceans 109, c03051, doi: 10.1029/ 2003jc001940. han l. 2005. estimating chlorophyll-a concentration using first-derivative spectra in coastal water. international journal of remote sensing 26, 5235–5244. hill d.e. & tedrow j.c.f. 1961. weathering and soil formation in the arctic environment. american journal of science 259, 84–101. hölemann j.a., schirmacher m., kassens h. & prange a. 1999. geochemistry of surficial and ice-rafted sediments from the laptev sea (siberia). estuarine, coastal shelf science 49, 45–59. holland m.m., bitz c.m., eby m. & weaver a.j. 2001. the role of ice–ocean interactions in the variability of the north atlantic thermohaline circulation. journal of climate 14, 656–675. hunkins k., thorndike e.m. & mathieu g. 1969. nepheloid layers and bottom currents in the arctic ocean. journal of geophysical research 74, 6995–7008. jakobsson m., gardner j.v., vogt p., mayer l.a., armstrong a., backman j., brennan r., calder b., hall j.k. & kraft b. 2005. multibeam bathymetric and sediment profiler evidence for ice grounding on the chukchi borderland, arctic ocean. quaternary research 63, 150–160. jakobsson m., lovlie r., al-hanbali h., arnold e., backman j. & morth m. 2000. manganese color cycles in arctic ocean sediments constrain pleistocene chronology. geology 28, 23–26. jakobsson m., macnab r., mayer l., anderson r., edwards m., hatzky j., schenke h.-w. & johnson p. 2008. an improved bathymetric portrayal of the arctic ocean: implications for ocean modeling and geological, geophysical and oceanographic analyses. geophysical research letters 35, l07602, doi: 10.1029/2008gl033520. jakobsson m., polyak l., edwards m.h., kleman j. & coakley b.j. 2008. glacial geomorphology of the central arctic ocean: chukchi borderland and the lomonosov ridge. earth surface processes and landforms 33, 526–545. jones e.p. 2001. circulation in the arctic ocean. polar research 20, 139–146. kalinenko v.v. 2001. clay minerals in sediments of the arctic seas. lithology and mineral resources 36, 362–372. kim j.-h., rimbu n., lorenz s.j., lohmann g., nam s.-i., schouten s., rühlemann c. & schneider r.r. 2004. north pacific and north atlantic sea-surface temperature variability during the holocene. quaternary science reviews 23, 2141–2154. knies j. & vogt c. 2003. freshwater pulses in the eastern arctic ocean during saalian and early weichselian ice-sheet collapse. quaternary research 60, 243–251. kwok r. 2000. recent changes in arctic ocean sea lee motion associated with the north atlantic oscillation. geophysical research letters 27, 775–778. kwok r. & rothrock d.a. 1999. variability of fram strait ice flux and north atlantic oscillation. journal of geophysical research—oceans 104, 5177–5189. löwemark l., jakobsson m., mörth m. & backman j. 2008. arctic ocean manganese contents and sediment colour cycles. polar research 27, 105–113. macquaker j.h.s., keller m.a. & taylor k.g. 1999. sequence stratigraphic analysis of the lower part of the pebble shale unit, canning river, northeastern alaska. in anwr assessment team: the oil and gas resource potential of the 1002 area, arctic national wildlife refuge, alaska. usgs open-file report 98-34. pp. ss1–ss15. denver, co: us geological survey. mangerud j., jakobsson m., alexanderson h., astakhov v., clarke g.k.c., henriksen m., hjort c., krinner g., lunkka j., moller p., murray a., nikolskaya o., saarnisto m. & svendsen j.i. 2004. ice-dammed lakes and rerouting of the drainage of northern eurasia during the last glaciation. quaternary science reviews 23, 1313–1332. martinson d.g., pisias n.g., hays j.d., imbrie j., moore t.c. jr. & shackleton n.j. 1987. age dating and the orbital theory of the ice ages: development of a high-resolution 0 to 300,000-year chronostratigraphy. quaternary research 27, 1–29. mccave i.n., kiefer t., thornalley d.j.r. & elderfield h. 2005. deep flow in the madagascar–mascarene basin over the last 150 000 years. philosophical transactions of the royal society a 363, 81–99. mcmanus d.a., kelley j.c. & creager j.s. 1969. continental shelf sedimentation in an arctic environment. geological society of america bulletin 80, 1961–1984. moore d.m. & reynolds r.c. 1997. x-ray diffraction and the identification and analysis of clay minerals. oxford: oxford university press. mørup s., saksager o., madsen m.b., bentzon m.d. & koch c.j.w. 1990. weathering of basalt in an arctic climate. hyperfine interactions 57, 2269–2273. mysak l. 2001. patterns of arctic circulation. science 293, 1269–1270. naidu a.s., burrell d.c. & hood d.w. 1971. clay mineral composition and geologic significance of some beaufort sea sediments. journal of sedimentary petrology 41, 691–694. naidu a.s. & mowatt t.c. 1983. sources and dispersal patterns of clay minerals in surface sediments from the continental shelf areas off alaska. geological society of america bulletin 94, 841–854. nørgaard-pedersen n., mikkelsen n. & kristoffersen y. 2007. arctic ocean record of last two glacial–interglacial cycles off north greenland/ellesmere island—implications for glacial history. marine geology 244, 93–108. nørgaard-pedersen n., spielhagen r.f., erlenkeuser h., grootes p.m., heinemeier j. & knies j. 2003. arctic ocean during the last glacial maximum: atlantic and polar domains of surface watermass distribution and ice cover. palaeoceanography 18, 1063. ortiz j., polyak l., adler r., jakobsson m. & darby d. 2007. late pleistocene sediment provenance on the mendeleev clay mineral cycles from the northwind ridgel.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 195 ridge, arctic ocean, from xrf elemental analysis and diffuse spectral reflectance measurements. eos, transactions of the american geophysical union 88, fall meeting supplement, abstract pp51a-0184. ortiz j.d., polyak l., grebmeier j.m., darby d., eberl d.d., naidu s. & nof d. 2009. provenance of holocene sediment on the chukchi–alaskan margin based on combined diffuse spectral reflectance and quantitative x-ray diffraction analysis. global and planetary change 68, 73–84. ortiz j.d., polyak l., jakobsson m. & darby d. 2006. quaternary inferences on central arctic ocean circulation and sediment provenance based on diffuse spectral reflectance analysis. eos, transactions of the american geophysical union 87, fall meeting supplement, abstract os53b-1098. parrish j.t., droser m.l. & bottjer d.j. 2001. a triassic upwelling zone: the shublik formation, arctic alaska, u.s.a. journal of sedimentary research 71, 272–285. petschick r., kuhn g. & gingele f. 1996. clay mineral distribution in surface sediments of the south atlantic: sources, transport, and relation to oceanography. marine geology 130, 203–229. pfirman s., haxby w.f., colony r. & rigor i. 2004. variability in arctic sea ice drift. geophysical research letters 31, l16402, doi: 10.1029/2004gl020063. phillips r. & grantz a. 1997. quaternary history of sea ice and palaeoclimate in the amerasia basin, arctic ocean, as recorded in the cyclical strata of northwind ridge. geological society of america bulletin 109, 1101–1115. phillips r.l. & grantz a. 2001. regional variations in the provenance and abundance of ice-rafted clasts in arctic ocean sediments: implications for the configuration of late quaternary oceanic and atmospheric circulation in the arctic. marine geology 172, 91–115. pickart r.s. 2004. shelfbreak circulation in the alaskan beaufort sea: mean structure and variability. journal of geophysical research—oceans 109, c04024, doi: 10.1029/ 2003jc001912. polyak l., bischof j., ortiz j., darby d.a., channell j., xuan c., kaufman d., lovlie r., schneider d. & adler r. 2009. late quaternary stratigraphy and sedimentation patterns in the western arctic ocean. global and planetary change 68, 4–17. polyak l., curry w.b., darby d.a., bischof j. & cronin t.m. 2004. contrasting glacial/interglacial regimes in the western arctic ocean as exemplified by a sedimentary record from the mendeleev ridge. palaeogeography, palaeoclimatology, palaeoecology 203, 73–93. polyak l., darby d.a., bischof j. & jakobsson m. 2007. stratigraphic constraints on late pleistocene glacial erosion and deglaciation of the chukchi margin, arctic ocean. quaternary research 67, 234–245. polyak l., edwards m.h., coakley b.j. & jakobsson m. 2001. ice shelves in the pleistocene arctic ocean inferred from glaciogenic deep-sea bedforms. nature 410, 453–457. polyak l., niessen f., gataullin v. & gainanov v. 2008. the eastern extent of the barents–kara ice sheet during the last glacial maximum based on seismic-reflection data from the eastern kara sea. polar research 27, 162–174. polyakov i.v., bekryaev r.v., alekseev g.v., bhatt u.s., colony r.l., johnson m.a., maskshtas a.p. & walsh d. 2003. variability and trends of air temperature and pressure in the maritime arctic, 1875–2000. journal of climate 16, 2067–2077. polyakov i.v. & johnson m.a. 2000. arctic decadal and interdecadal variability. geophysical research letters 27, 4097–4100. polyakov i.v., proshutinsky a.y. & johnson m.a. 1999. seasonal cycles in two regimes of arctic climate. journal of geophysical research—oceans 104, 25 761–25 788. poore r., osterman l., curry w. & phillips r. 1999. late pleistocene and holocene meltwater events in the western arctic ocean. geology 27, 759–762. press w.h., teukolsky s.a., vetterling w.t. & flannery b.p. 1992. numerical recipes in fortran 77: the art of scientific computing. 2nd edn. cambridge: cambridge university press. proshutinsky a.y. & johnson m.a. 1997. two circulation regimes of the wind-driven arctic ocean. journal of geophysical research—oceans 102, 12 493–12 514. reimnitz e., mccormick m., mcdougall k. & brouwers e. 1993. sediment export by ice rafting from a coastal polynya, arctic alaska, u.s.a. arctic and alpine research 25, 83–98. rigor i.g., wallace j.m. & colony r.l. 2002. response of sea ice to the arctic oscillation. journal of climate 15, 2648–2663. rodeick c. 1979. the origin, distribution, and depositional history of gravel deposits on the beaufort sea continental shelf, alaska. usgs open-file report 79-234. denver, co: us geological survey. rudels b., jones e.p., anderson l.g. & kattner g. 1994. on the intermediate depth waters of the arctic ocean. in o.m. johannessen et al. (eds.): the polar oceans and their role in shaping the global environment. pp. 33–46. washington, d.c.: american geophysical union. rudels b., jones e.p., schauer u. & eriksson p. 2004. atlantic sources of the arctic ocean surface and halocline waters. polar research 23, 181–208. serreze m.c., maslanik j.a., scambos t.a., fetterer f., stroeve j., knowles k., fowler c., drobot s., barry r.g. & haran t.m. 2003. a record minimum arctic sea ice extent and area in 2002. geophysical research letters 30, article no. 1110, doi: 10.1029/2002gl016406. shimada k., kamoshida t., itoh m., nishino s., carmack e., mclaughlin f., zimmermann s. & proshutinsky a. 2006. pacific ocean inflow: influence on catastrophic reduction of sea ice cover in the arctic ocean. geophysical research letters 33, l08605, doi: 10.1029/2005gl025624. steele m., ermold w. & zhang j. 2008. arctic ocean surface warming trends over the past 100 years. geophysical research letters 35, l02614, doi: 10.1029/2007gl031651. stein r. 2008. arctic ocean sediments: processes, proxies, and paleoenvironment. oxford: elsevier. clay mineral cycles from the northwind ridge l.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd196 stein r., dittmers k.h., fahl k., kraus m., matthiessen j., niessen f., pirrung m., polyakova y.i., schoster f., steinke t. & fütterer d.k. 2004. arctic (palaeo) river discharge and environmental change: evidence from the holocene kara sea sedimentary record. quaternary science reviews 23, 1485–1511. svendsen j.i., alexanderson h., astakhob v.i., demidov i., dowdeswell j.a., funder s., gataullin v., henriksen m., hjort c., houmark-nielsen m., hubberten h.w., ingolfsson o., jakobsson m., kjaer k.h., larsen e., lokrantz h., lunkka j.p., lysa a., mangerud j., matiouchkov a., murray a., moller p., niessen f., nikolskaya o., polyak l. saarnisto m., siegert c., siegert m., spielhagen r.f. & stein r. 2004. late quaternary ice sheet history of northern eurasia. quaternary science reviews 23, 1229–1271. thompson d.w.j. & wallace j.m. 1998. the arctic oscillation signature in the wintertime geopotential height and temperature fields. geophysical research letters 25, 1297–1300. thompson d.w.j. & wallace j.m. 2000a. annular modes in the extratropical circulation. part i: month-to-month variability. journal of climate 13, 1000–1016. thompson d.w.j. & wallace j.m. 2000b. annular modes in the extratropical circulation. part ii: trends. journal of climate 13, 1018–1036. toracinta e.r., bromwich d.h. & wei h. 2002. high resolution lgm simulations over the laurentide ice sheet using polar mm5. paper presented at the twelfth psu/ ncar mesoscale model users’ workshop, 24–25 june, boulder, co, usa. van der zee c., roberts d.r., rancourt d.g. & slomp c.p. 2003. nanogoethite is the dominant reactive oxyhydroxide phase in lake and marine sediments. geology 31, 993–996. viscosi-shirley c., mammone k., pisias n. & dymond j. 2003. clay mineralogy and multi-element chemistry of surface sediments on the siberian-arctic shelf: implications for sediment provenance and grain size sorting. continental shelf research 23, 1175–1200. viscosi-shirley c., pisias n. & mammone k. 2003. sediment source strength, transport pathways and accumulation patterns on the siberian-arctic’s chukchi and laptev shelves. continental shelf research 23, 1201–1225. vogt c. 1997. regional and temporal variations of mineral assemblages in arctic ocean sediments as climatic indicator during glacial/interglacial changes. reports on polar research 251. bremerhaven: alfred wegener institute for polar and marine research. vogt c. 2009. data report: semiquantitative determination of detrital input to acex sites based on bulk sample x-ray diffraction data. in j. backman et al.: proceedings of the integrated ocean drilling program 302. edinburgh: integrated ocean drilling program management international. vogt c. & knies j. 2008. sediment dynamics in the eurasian arctic ocean during the last deglaciation—the clay mineral group smectite perspective. marine geology 250, 211–222. vogt c. & knies j. 2009. sediment pathways in the western barents sea inferred from clay mineral assemblages in surface sediments. norwegian journal of geology 89, 41–55. wahsner m., müller c., stein r., ivanov g., levitan m., shelekhova e. & tarasov g. 1999. clay–mineral distribution in surface sediments of the eurasian arctic ocean and continental margin as indicator for source areas and transport pathways—a synthesis. boreas 28, 215–233. wang j. & ikeda m. 2000. arctic oscillation and arctic sea-ice oscillation. geophysical research letters 27, 1287–1290. weingartner t.j., aagaard k., woodgate r., danielson s., sasaki y. & cavalieri d. 2005. circulation on the north central chukchi sea shelf. deep-sea research part ii 52, 3150–3174. williams w.j., melling h., carmack e.c. & ingram r.g. 2008. kugmallit valley as a conduit for cross-shelf exchange on the mackenzie shelf in the beaufort sea, journal of geophysical research—oceans 113, c02007, doi: 10.1029/2006jc003591. winkler a., wolf-welling t.c.w., stattegger k. & thiede j. 2002. clay mineral sedimentation in high northern latitude deep-sea basins since the middle miocene (odp leg 151, naag). international journal of earth sciences 91, 133–148. winter b.l., johnson c.m. & clark d.l. 1997. strontium, neodymium, and lead isotope variations of authigenic and silicate sediment components from the late cenozoic arctic ocean: implications for sediment provenance and the source of trace metals in seawater. geochimica et cosmochimica acta 61, 4181–4200. woodgate r.a., aagaard k., swift j.h., falkner k.k. & smethie w.m. 2005. pacific ventilation of the arctic ocean’s lower halocline by upwelling and diapycnal mixing over the continental margin. geophysical research letters 32, l18609, doi: 10.1029/2005gl023999. yacobi y.z. & gitelson a.a. 2000. simultaneous remote measurement of chlorophyll and total seston in productive inland waters. verhandlungen des internationalen verein limnologie 27, 2983–2986. zhang x., ikeda m. & walsh j.e. 2003. arctic sea ice and freshwater changes driven by the atmospheric leading mode in a coupled sea ice–ocean model. journal of climate 16, 2159–2177. clay mineral cycles from the northwind ridgel.n. yurco et al. polar research 29 2010 176–197 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 197 captain scott: icy deceits and untold realities book review captain scott: icy deceits and untold realities, by krzysztof sienicki, berlin, open academic press, 2016, 776 pp., €86.27 (hardback), isbn-13: 978-8394452001 captain scott holds a unique position in human exploration in that, despite his failures, he has obtained a status often above and beyond his ultimately more successful adversary roald amundsen. in a field which only celebrates the victor how did this come to pass? perhaps it is because that, although failing to reach the south pole first, his subsequent demise on the icy continent symbolized the extremes humans undergo in the name of exploration, the very real prospect of failure, and the strength of the human spirit. his untimely death elevated scott from second place finisher to that of martyr – a man sacrificing himself in the name of discovery. until now a multitude of books have analysed scott’s expedition to the pole in great detail, without ever questioning whether scott’s legendary status is justified or indeed deserved. in krzysztof sienicki’s new book, captain scott: icy deceits and untold realities, the question of whether scott is deserving of such high esteem is put to the test. the author has reviewed the records and offers additional information and novel interpretations bearing on the notorious expedition. the author argues that the evidence shows falsification of meteorological data from the original collectors, as well as erroneous explanations and conclusions by authors who have written about the same expedition. the book is divided into three volumes. the first volume deals with all weather related issues of the expedition. in particular, analysis is presented of the extreme cold weather conditions in late february and early march 1912, which, according to scott’s message to the public, were the final blow to his party’s demise. the author argues that the extreme cold weather conditions were an exaggeration on the part of scott. the author also rejects scott’s account of a 10-day-long blizzard towards the end of march. in the second volume, the author takes on the logistics of scott’s journey to the pole and the simultaneous actions of the cape evans party commanded by dr simpson under scott’s written orders. in analysing the distribution of food and fuel rations at the barrier stage the author questions scott’s management of the expedition and the actions taken at cape evans. he argues that dr simpson mutinied and under a false rationale sailed back to new zealand and then on to england. the author claims that the actual location of the last camp was not 11 but 22 miles from one ton depot, and that scott’s error, intentional or otherwise, was not corrected by dr atkinson’s search party. in the third volume, the author tackles the causes of the captain scott party deaths as argued by other authors and scott himself. the author’s own startling conclusion is that the party, from about 2 february 1912, decided not to return to home base at cape evans. the most controversial claim in this almost 800-page volume is that scott’s party did not perish in 1912 because of weather and starvation. according to sienicki’s calculations, scott’s party had full food/fuel rations until at least 27 march 1912 and could have made it back to cape evans. the author also gives a large portion of the book to criticizing modern writers of scott’s expedition, many of whom are notable in their fields. the author argues that the false data and unsound analyses in their books have contributed to the myth that captain scott was defeated by unforeseen circumstances rather than the fallibility of scott or his party. the book offers a novel take on the famous expedition and its appeal lies in its controversial claims and detailed analyses. taken at face value, the author’s interpretation is persuasive. however, readers are strongly advised to consult other writers’ analyses before forming an opinion about the causes of the failure of the expedition. the author’s arguments and findings stand in profound contradiction with the majority of authors on the subject and have been disputed by historical commentators and scientists alike. steven attenborough ul. spokojna 9a, pl-05-806 komorów, poland satten2001@gmail.com © 2017 steven attenborough https://doi.org/10.1080/17518369.2017.1288845 polar research, 2017 vol. 36, 1288845 http://www.tandfonline.com http://www.tandfonline.com book review no job name b o o k r e v i e w por_182 463..466 review of health of antarctic wildlife: a challenge for science and policy, edited by knowles r. kerry & martin j. riddle (2009). dordrecht: springer. 470 pp. isbn 978-3-540-93922-1. climate change and disease, among other factors, play an important role in the regulation and evolution of animal populations through the differential survival of individuals (holmes 1996; harvell et al. 2002). the study and monitoring of disease is important because diseases are likely to be spread more rapidly now than in the recent past because of increased globalization and rapid humaninduced climate change (daszak et al. 2000; ward & lafferty 2004). antarctic wildlife offers a unique opportunity to study disease spread in terms of globalization and climate change because: (1) antarctic animals are increasingly exposed to humans and other disease vectors, such as introduced species; and (2) there is strong evidence of climatic changes in and around antarctica (mayewski et al. 2009), which together may affect the composition and virulence of pathogens or increase the overlap between antarctic and other seabirds and their parasites (e.g., kovats et al. 2001). in their new book, health of antarctic wildlife: a challenge for science and policy, two pioneer researchers of the effects of humans on antarctic wildlife, knowles kerry and martin riddle, bring together what is known about disease prevalence and the management of disease outbreaks in the antarctic. this book and its many contributors—28 in all—provide an up-to-date overview of the health of antarctic birds and seals. for any practising biologist, ecologist or veterinarian interested in antarctic biology this book is immensely valuable, not only because it brings together information from a wide range of fields and expertise, but also and perhaps most critically it describes exactly how suspicious die-offs should be treated to minimize the potential spread of disease, and to reduce the risk to the human researchers most likely to discover such events. antarctica is unlikely to share many of the diseases found in the neighbouring southern continents on account of the temporal (many millions of years) and geographical/spatial isolation of the continent by the southern ocean, which forms a functional barrier across which few animals, among them, birds and seals, can cross. most animals in antarctica and on the surrounding sub-antarctic islands have evolved in relative isolation, which has limited their contact with disease and inhibits the introduction of vectors or intermediate hosts, such as ectoparasites. consequently, antarctic animals are likely to have reduced immune capabilities for fending off introduced disease. indeed, there have been only two reported cases of mass mortalities of antarctic wildlife: one of crabeater seals (labodon carcinophagus) and one of adélie penguins (pygoscelis adeliae) (laws & taylor 1957; gardner et al. 1997); two smaller, more insidious, mortality events occurred in the sub-antarctic involving the amsterdam albatross (diomedia amsterdamensis) and hooker’s sea lions (phocarctos hookeri) (weimerskirch 2004; wilkinson et al. 2006). however, the wildlife in antarctica is no longer as isolated as in the past because of the ease of transport to antarctica and the increasing number of people visiting correspondence clive r. mcmahon, school for environmental research, charles darwin university, casuarina campus, darwin, northern territory 0909, australia. e-mail: clive.mcmahon@cdu.edu.au polar research 29 2010 463–466 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 463 mailto:mcmahon@cdu.edu.au the southern polar regions, including scientists, fishers and tourists, a topic covered comprehensively in health of antarctic wildlife. not only are more people visiting the antarctic, but rapid and widespread travel within antarctica is now commonplace. this behaviour increases the risk of disease spread, endemic and introduced alike. whereas disease spread is not a novel concern (murray 1964), the issue of disease introduction has, until the publication of health of antarctic wildlife, received relatively little scientific attention in antarctica. one possible reason for this is that little is known of diseases in antarctic animal populations, in particular the introduction of disease, and probably more importantly the manifestation of as yet undiscovered or mutating diseases (for an example of a recently discovered novel virus, see linn et al. 2001). another explanation may have to do with the rarity with which diseased individuals are observed. this may change if disease outbreaks occur more frequently or if they are more readily observed because of increased scientific observation in antarctica. animal behaviour, including human behaviour, is an important component in the spread and maintenance of disease (mccallum et al. 2001). as such, it is important that it forms the basis of any assessments investigating or managing disease. sadly, in health of antarctic wildlife, animal behaviour other than human behaviour receives little focused attention, as do life-history studies in general (see below). of particular concern for the spread of disease is the human propensity to alter ecosystems through their behaviour, e.g., habitat modification and the introduction of invasive species, thereby altering the behaviour of animals. this brings into contact species that otherwise would have very low chances of interacting, increasing the probability of disease spread. moreover, the fact that many antarctic taxa such as seals, penguins and antarctic petrels form dense aggregations highlights how animal behaviour can promote the easy intracolony spread of disease. because most colonies tend to be separated by large distances, the potential for intercolony infection is probably low, but this is currently difficult to quantify because of the paucity of species-specific behavioural information. little is known of individual animal movements between breeding colonies and/or the extent of mixing between populations. diseases can be spread between colonies via other means, such as predators and scavengers. the south polar skua (catharacta maccormicki) is such a predator/scavenger. skuas are mobile predators that feed/scavenge on all antarctic taxa, and travel freely between the northern and southern hemispheres (devillers 1977), and may therefore be significant contributors to intercolony disease spread. the clear need to integrate animal behaviour, e.g., migratory and dispersal behaviour, and animal biology and ecology in general, receives little coverage in health of antarctic wildlife, in contrast to the study of human behaviour. human activity in antarctica can promote disease spread and outbreaks by a number of direct and indirect mechanisms, and this is covered thoroughly in health of antarctic wildlife. people may act as vectors for infectious agents, either by bringing non-indigenous pathogens into the region or by translocating indigenous pathogens. although humans are not the only mechanism for disease incursion to antarctica, they are an important mechanism for disease or pathogen introduction because of their mobility and diets. of particular concern are imported poultry products, including eggs, egg powder and frozen or freeze-dried meat, which may be sources of viruses and bacteria that are pathogenic to humans, seals and seabirds. poultry has been linked to the transmission of newcastle disease in antarctic seabirds, and because antibodies to newcastle disease have been found in many birds (e.g., gardner et al. 1997, and references therein), it follows that viral (and other) diseases, such as avian influenza, can be easily transmitted to antarctic birds through foodstuffs regularly consumed by humans in antarctica. vehicles, equipment and clothing used in antarctica can also carry pathogens if they are used for recreation, training or work in other locations before being used in antarctica. human activity may also result in stress to wildlife, a major contributing factor to the outbreak of disease (lafferty & holt 2003). humans may cause animals stress by polluting the antarctic environment (e.g., discharging sewage into the ocean from research stations or ships at sea) or by creating food shortages, as when fisheries compete for the same food stocks. researchers and tourists disturb animals in other ways. stress to animals may also be induced by climate change and habitat destruction, and fragmentation that results from human activities. it is often thought that because antarctic species are well adapted to survive under extreme environmental conditions that they are immune to environmental stress—this is clearly not the case. prevention in most cases is probably the most effective way of dealing with diseases in antarctica, simply because it is not easy to observe clinical ante-mortem symptoms in the field. to prevent pathogenic disease from being introduced into antarctica, strict quarantine measures need to be implemented, and it is encouraging to note that there are now strict pre-departure checks in place to restrict the accidental introduction of pathogens. the problem here is one of compliance, especially on illegal vessels (generally fishing vessels) entering antarctic waters. such illegal vessels, many of which originate in asia, where diseases like avian influenza are prevalent book review polar research 29 2010 463–466 © 2010 the author, journal compilation © 2010 blackwell publishing ltd464 (webby & webster 2001), are of particular concern and high risk. this risk is exemplified by the presence of avian influenza antibodies in antarctic seabirds (morgan & westbury 1988; austin & webster 1993), indicating that these birds have at some stage been exposed to the virus. of concern are the high mutation rates of viruses: it is feasible that a benign form may under certain circumstances (e.g., climate change) morph rapidly into a virulent form that bypasses the immune response, resulting in serious pathological consequences and pandemic disease. health of antarctic wildlife makes an important research and practical contribution by highlighting the quarantine measures that australia in particular is taking to limit the probability of disease introduction into antarctica. such proactive quarantine measures are likely to be the most effective way of limiting potential disease outbreaks. much remains to be learned about disease in antarctic wildlife if the risk of disease introduction is to be managed effectively. little information is currently available on which to base reliable risk assessment. sound research and long-term monitoring programmes will reduce the risk of large-scale infections and reduce the vulnerability of wildlife in antarctica to disease outbreak. health of antarctic wildlife provides an invaluable first step to achieving this by summarizing what is known to date and delineating practical measures to manage outbreaks. the book also outlines the key research requirements that will contribute to the better understanding and management of disease in antarctica, including: • baseline information on disease agents so that native and exotic disease agents can be distinguished and regional and seasonal variation of disease can be understood. • baseline information on population size, health status, mortality, migratory behaviour and population dynamics. • the distribution and abundance of potential pathogens. • the processes that promote disease outbreak, e.g., climate change and stress. • the survival of pathogens on foodstuffs, vehicles and clothing. • the effectiveness of antarctic sewage treatment to remove pathogens. • the likelihood of transfer of pathogens. • monitoring affected populations, and recovering corpses to confirm disease occurrence. diseases play an important role in evolutionary and ecological processes, so collecting this kind of information, along with developing practical methods for the on-site investigation of disease incidents, will undoubtedly contribute to the ultimate aim of sound conservation of a unique part of our planet. although health of antarctic wildlife covers much ground thoroughly, i was left wondering where the papers on population ecology and demography were. animal life history can have a profound effect on the spread or maintenance of disease in populations. information regarding animal movement and habitat use, how animals interact with one another and other animals, how population density affects animal interaction and movement, and how changes in population size affect animal behaviour are all vital pieces of information to map and assess the spread of disease. ultimately life-history and vital-rate information are crucial components needed for designing and implementing management strategies, such as the management of badgers in the uk to curtail bovine tuberculosis (woodroffe et al. 2009). indeed, an increasingly important component of managing disease is to use models to simulate and predict potential rates of spread. such models rely heavily on basic life-history information as inputs to quantify the rates at which animals will re-invade areas from which animals were removed: either killed by disease or culled to control disease. given the importance of integrating life-history information and disease behaviour to inform effective disease management and control, it was a little disappointing that this did not receive more attention in the book. a section describing and perhaps even presenting some easy-to-use tools that assess the effectiveness of removing animals for disease control (jenkins et al. 2008), or a section on how life history and environmental variability interact to drive disease spread, would have been most informative. many of these tools have only been developed very recently (e.g., mcmahon et al. 2010), and serve as motivation for a future antarctic wildlife health symposium. it has been 10 years since the symposium upon which this book is based was held, and it is timely, perhaps even overdue, that a follow-up symposium be held. given the importance of a broad ecological context, such a symposium might build on the excellent groundwork of this first meeting by taking a broader view of health in the antarctic by contextualizing the role of disease and health in managing the antarctic ecosystem as a whole: taking a “one-health approach” (daszak et al. 2007). this collaborative approach to understanding the processes of disease emergence links veterinary medicine, public health and ecological approaches in a single framework underpinned by evolutionary theory. this would not only greatly advance the field of study, it would also provide a framework from which to develop coordinated projects with the single goal of ensuring a functional ecosystem, by defining the role of disease in driving population change. the dynamics of disease emergence are complex and an integrated process such as the one-health approach is the best way forward for developing a sound understanding book review polar research 29 2010 463–466 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 465 of the mechanics of disease emergence and its effective management or containment. clive r. mcmahon references austin f.j. & webster r.g. 1993. evidence of orthoand paramyxoviruses in fauna from antarctica. journal of wildlife diseases 29, 568–571. daszak p., cunningham a.a. & hyatt a.d. 2000. emerging infectious diseases of wildlife—threats to biodiversity and human health. science 287, 443–449. daszak p., epstein j.h., kilpatrick a.m., aguirre a.a., karesh w.b. & cunningham a.a. 2007. collaborative research approaches to the role of wildlife in zoonotic disease emergence. in j.e. childs et al. (eds.): wildlife and emerging zoonotic diseases: the biology, circumstances and consequences of cross-species transmission. pp. 463–475. berlin: springer. devillers p. 1977. the skuas of the north american pacific coast. auk 94, 417–429. gardner h., kerry k., riddle m., brouwer s. & gleeson l. 1997. poultry virus infection in antarctic penguins. nature 387, 245. harvell d., mitchell c.e., ward j.r., altizer s., dobson a., ostfeld r.s. & samuel m.d. 2002. climate warming and disease risks for terrestrial and marine biota. science 296, 2158–2162. holmes j.c. 1996. parasites as threats to biodiversity in shrinking ecosystems. biodiversity and conservation 5, 975–983. jenkins h.e., woodroffe r. & donnelly c.a. 2008. the effects of annual widespread badger culls on cattle tuberculosis following the cessation of culling. international journal of infectious diseases 12, 457–465. kovats r.s., campbell-lendrum d.h., mcmichael a.j., woodward a. & cox j.s.h. 2001. early effects of climate change: do they include changes in vector-borne disease? philosophical transactions of the royal society of london b 356, 1057–1068. lafferty k.d. & holt r.d. 2003. how should environmental stress affect the population dynamics of disease? ecology letters 6, 654–664. laws r.m. & taylor r.j.f. 1957. a mass dying of crabeater seals, lobodon carcinophagus (gray). proceedings of the zoological society of london 129, 315–324. linn m.l., gardner j., warrilow d., darnell g.a., mcmahon c.r., field i., hyatt a.d., slade r.w. & suhrbier a. 2001. arbovirus of marine mammals: a new alphavirus isolated from the elephant seal louse, lepidophthirus macrorhini. journal of virology 75, 4103–4109. mayewski p.a., meredith m.p., summerhayes c.p., turner j., worby a., barrett p.j., casassa g., bertler n.a.n., bracegirdle t., garabato a.c.n., bromwich d., campbell h., hamilton g.s., lyons w.b., maasch k.a., aoki s., xiao c. & van ommen t. 2009. state of the antarctic and southern ocean climate system. reviews of geophysics 47, 38. mccallum h., barlow n. & hone j. 2001. how should pathogen transmission be modelled? trends in ecology & evolution 16, 295–300. mcmahon c.r., brook b.w., collier n. & bradshaw c.j.a. 2010. a spatially explicit spreadsheet modelling approach for optimizing the efficiency of reducing invasive animal density. methods in ecology and evolution 1, 53–68. morgan i.r. & westbury h.a. 1988. studies of viruses in penguins in the vestfold hills. hydrobiologia 156, 263–269. murray m.d. 1964. ecology of the ectoparasites of seals and penguins. in r. carrick et al. (eds.): biologie antarctique: premier symposium organise par le s.c.a.r., paris 2–8 septembre 1962. pp. 241–245. paris: hermann. ward j.r. & lafferty k.d. 2004. the elusive baseline of marine disease: are diseases in ocean ecosystems increasing? plos biology 2, 542–547. webby r.j. & webster r.g. 2001. emergence of influenza a viruses. philosophical transactions of the royal society of london b 356, 1817–1828. weimerskirch h. 2004. diseases threaten southern ocean albatrosses. polar biology 27, 374–379. wilkinson i.s., duignan p.j., castinel a., grinberg a., chilvers b.l. & robertson b.c. 2006. klebsiella pneumoniae epidemics: possible impact on new zealand sea lion recruitment. in a.w. trites et al. (eds.): sea lions of the world. pp. 385–403. fairbanks: alaska sea grant. woodroffe r., donnelly c.a., cox d.r., gilks p., jenkins h.e., johnston w.t., le fevre a.m., gourne f.j., cheeseman c.l., clifton-hadley r.s., gettinby g., hewinson r.g., mcinerney j.p., mitchel a.p., morrison w.i. & watkins g.h. 2009. bovine tuberculosis in cattle and badgers in localized culling areas. journal of wildlife diseases 45, 128–143. book review polar research 29 2010 463–466 © 2010 the author, journal compilation © 2010 blackwell publishing ltd466 the biostratigraphic position of the kap kflbenhavn formation based upon its foraminifera rolf w. feyling-hanssen feyling-hanssen, r . w. 1987: the biostratigraphic position of the kap kebenhavn formation based upon its foraminifera. polar research 5 n . s . , 345-346. rolf w . feyling-hanssen. department of micropaleontology, geological institute, aarhur university, d k 8000 aarhur c . denmark. two lithological units are distinguished in the kap kebenhavn formation (funder & hjort 1980; funder et al. 1984; funder et al. 1985): a lower member a composed mainly of clay, and an upper member b composed mainly of sand. an upper subunit of the latter. 8 2 , comprises silty deposits. these sediments are in many places deformed and disturbed, partly squeezed and overthrusted. most probably by subsequent overriding glaciers. this blurs the stratigraphic picture at many places. fossil foraminifera occur in many samples from the fine grained sediments of member a and of unit b2 and also in fig. 1. localities mentioned in the text. some samples from thc upper part of unit b1. some of the foraminiferal assemblages are well preserved, whereas others are in a poorer state of preservation. many samples were barren of foraminifera even though molluscan shells occurred in them. dissolution of the delicate calcium carbopate tests by ground water may have taken place. during periods of melting this water probably becomes acidic owing to percolation through the sediments which may be very rich in plant debris. foraminifera1 assemblages from member a are characterized by the planispiral species nonion erucopsis todd (1957). this species is an intermediate form between the oligocene-miocene nonion affine (reuss) and the pleistocene nonion barleeanum (williamson). nonion erucopsis often occurs abundantly, thus forming a nonion erucopsis assemblage zone. it sometimes occurs together with a probably not previously described elphi dium with a sharp, almost keeled periphery. sometimes car sidulina laevigata d’orbigny and carsidulina teretis tappan are more frequent than this elphidium. a few specimens of cibi cides grossa ten dam & reinhold may also be present. these assemblages do not reflect a quaternary arctic environment. but are much closer to upper pliocene assemblages from lodin elv. east greenland (feyling-hanssen et al. 1982). clyde fore land, and the qivituq peninsula, baffin island (feyling-hanss.cn 1976,1980,1985). they are also very similar to upper pliocene assemblages in borings from the central north sea (king 1983; feyling-hanssen 1986). the nonion erucopsis assemblages from member a of the kap k0benhavn formation are thus of upper pliocene age. sediment samples from the upper part of unit b1 and the lower part of unit 8 2 contain well preserved foraminifera1 assemblages. even though the small species nonion nioeum lafrenz dominates these assemblages, the large, conspicuous, planispiral species elphidiella rolfi gudina & palovova char acterizes them. (this species was referred to as elphidiella cf. subcarinata in funder et al. 1985). elphidiella rolji was described from uppermost pliocene/lowermost pleistocene deposits of ajon island, northern chukotka, ussr (gudina et al. 1984). elphidiella hannai (cushman & grant 1927) is found together with elphidiella rolfi in the plio-pleistocene deposits of the ajon island. and a few specimens of this species are also found together with e. rolfi in the kap kdbenhavn formation. elphi diella hannai is known from pliocene/pleistocene transitional deposits in the nome area (cushman 1941), o n the seward peninsula (hopkins et al. 1974), in beaufort sea borings (mcneil et al. 1982) and particularly from the southern north sea basin (la. doppert 1980). 346 rolf w . feyling-harmen the elphidiella r o b assemblage zone of the upper unit b1 and lower unit b2 of the kap kebenhavn formation thus marks the transition between the pliocene and the pleistocene. samples from the upper and major part of unit 8 2 usually contain well preserved foraminiferal assemblages with large amounts of elphidium excauatum (terquem). this species occurs together with nonion nioeum, nonion orbiculare (brady). elphidrum rutulaturn todd and buccella frigida (cushman). scattered specimens of elphidiella hannai and e . ro@ are also present assemblages from the lower part of these deposits contain many specimens of the families polymor phinidae and glandulinidae. whereas cmsidulina reniforrne d’orbigny, elphidium bartlelli cushman and elphidiwn asklundi brotzen are more important in the upper part of the subunit. many specimens of elphidium excavarurn from the lower part of these deposits have a more or less subacute periphery. whereas they are more broadly rounded in the upper part. some specimens of the large and characteristic elphidiella gorbunoui stschedrina also occur in the upper part of this elphrdium exravatum assemblage zone of the kap kabenhavn formation. this elphrdium excavatum zone. particularly its upper part. reflects a high-arctic environment. comparison with pleistocene assemblages from many parts of the northern hemisphere (i.a. cushman 1941; hopkins et al. 1974; gudina et al. 1984) shows that i t belongs to the lower part of the pleistocene. in particular. comparison w i t h foraminiferal assemblages i n north sea borings (i.a. asbj0rnsdottir 1987) places the eiphidium excaoatum assemhlage zone of the kap k ~ b e n h a v n formation in the lower part of the early pleistocene. thc foraminifera thus reveal that the kap k ~ h e n h a v n for mation. or at least parts of i t . wab deposited on an inner shelf. in a sublittoral to littoral environment during the upper pliocene to lower early pleistocene. open water must have occurred, at least seaxonally. in thc area during this period. this conclusion is in good agreement with results reached by funder and co workers already in 1984. references asblornsdottir. l. 1y87: thejosephine boring (3oil3-2.r). cen tral north sea. unpublished thesis. geol. inst.. aarhus lniversity. 150 pp cushman. j . a . i y l l . somc fossil foraminifera from alaska: ciuhman lahoratory for foraminifera1 research con tribution 227. 32-38 cushman. j . a . 82 grant. u . s . . i v . 1927: late tertiary and ouaternary elphidiums of the west coast of north america. sun diego sociec of natural hitton. transactions 5/61, 6% r?. doppert. j . w . c. 1980: lithostratigraphy and biostratigraphy of marine neogene deposits in the netherlands. mededelingen van de geologuche stichting 32-16, 255-311. feyling-hanssen, r . w . 1976: the clyde foreland formation, a micropaleontological study of quaternary stratigraphy. 1st int. syrnp. on benthonic foraminifera of continental margins, pi. b: paleoecology and biosfraligraphy, maritime sediments, spec. pub. i . 31s377. feyling-hanssen, r. w . 1980: microbiostratigraphy of young cenozoic marine deposits of the qivituq peninsula, baffin island. marine micropaleontology 5 , 15?-184. feyling-hanssen. r . w . 1985: late cenozoic marine deposits of east baffin island and east greenland, microbio stratigraphy correlation age. pp. 356393 in andrews. j. t. (ed.): quaternary enuironments: eastern canadian arctic, baffin brv. and wesi greenland. allen and unwin. london, sydney. feyling-hanssen. r . w. 1986: grznsen mellem tertier og kvartzr i nordsqen og i arktis. fastlagt og korreleret ved hjzlp af benthoniske foraminiferer. dansk geol. foren., arsskrift for 1985, 19-33. feyling-hanssen. r . w., funder, s . & petersen. k. 1982: the lodin elv formation; a plio-pleistocene occurrence in greenland. bull. geol. s o c . denmark 31. 81-106. funder. s . , abrahamsen. n.. bennike, 0. & feyling-hanssen, r . w. 1985: a forested arctic, evidence from north greenland. geology. 542-546. funder. s . , bennike. 0.. mogensen. g . s . , noe-nygaard, b.. pedersen, s. a . s . & petersen, k. s. 1984: the kap kebenhavn formation, a late cainozoic sedimentary sequence in north greenland. rapport gr@nlands geo logirke undersmgelse 120, 9-18. funder. s . & hjort, c. 1980: a reconnaissance of the quat ernary geology of eastern north greenland. rapport gr@n lands geologiske ljnders@gelse 99, 99-105. gudina. v . i . , lashtabeg. v . a . . levchuk. l. k., polovova, t . p., sukhoroslov, v . l. 1984: the pliocene/pleistocene boundary in northern chukotka. based on foraminifera, transaction of the institute of geology and geophysics 560, akademia nauk sssr. s.o. 104 pp. hopkins, d . m., rowland, r . w . . echols. r . e . & valentine, p. c. 1974: an anvilian (early pleistocene) marine fauna from western seward peninsula, alaska. quaternary research 4(4), 44-470. king. c. & hughes, m. j . (contributor) 1983: cainozoic micro palaeontological biostratigraphy of the north sea. institute of geological sciences, report 8217. 40 pp. mcneil. d. h . , ioannides. n. s . & dixon. j . 1982: geology and biostratigraphy of the dome gulf et al. ukalerk c-50 well, beaufort sea. geological survey of canada. paper 80-32. 1-17. todd. r . 1957: foraminifera from carter creek, northeastern alaska. u . s . geological survey. professional paper 294-f, d l 2 3 5 . karst and karstification in gypsiferous beds in mathiesondalen, central spitsbergen, svalbard 0. salvigsen, 0 . lauritzen a n d j. mangerud salvigsen, o., lauritzen, 0. & mangerud. j. 1983: karst and karstification in gypsiferous beds in mathiesondalen, central spitsbergen, svalbard. polar research 1 n . s . , 83-88. oslo, recent karst forms in gypsiferous beds are reported from mathiesondalen in central spitsbergen, where several sinkholes (dolines) and swallow holes have been formed after the deposition of holocene raised beach sediments. the bedrock of the area is mostly interbedded gypsudanhydrite and dolomites of the carboniferous ebbadalen formation. otto salvigsen and omulf lauritzen, norsk polarinstitun, rolfstangueien 12, 1330 oslo lufthaun; jan mangerud, geologisk institutl, aud. b, uniuersitetet i bergen, 5014 bergen, norway. june 1982 (revired november 1982). introduction in the area around mathiesondalen in biinsow land east of billefjorden (fig. l), carboniferous and permian beds dip gently to the south. the outer part of the valley is covered by holocene raised beach sediments in the form of terraces and beach ridges (feyling-hanssen 1955; lau ritzen & salvigsen in press). the valley floor itself is occupied by a braided river system, and small tributary streams have eroded gullies in the unconsolidated sediments. the underlying rocks are mostly interbedded evaporites and dolomites of the ebbadalen formation (cutbill & challinor 1965), a formation described in detail by holliday & cutbill (1972) and johannessen (1980). the gypsiferous beds in the outer part of mathieson dalen are downfaulted along local lineaments con nected with the billefjorden fault zone (harland et al. 1974) causing almost flat lying evaporites to form the bedrock of the outer part of the valley and on the sides of the mountains further east. the post-depositional tectonic activity has caused prominent cracks and fissures in the bedrock, thus allowing the percolation of surface water. the geomorphological significance of rock sol ution in limestone/dolomite areas in spitsbergen has been discussed by corbel (1957, 1960) and helldcn (1974). orvin (1944) described springs in connection with the limestone area near horn sund in the southern part of spitsbergen. else where karst forms are most frequent and best developed in limestone and dolomite, partly because these rocks are more abundant than other soluble rock types (sweeting 1968). here we describe karst phenomena in gypsudanhydrite beds in an area at the mouth of mathiesondalen. observations large, closed depressions and other karst features occur in the raised beaches in the outer part of mathiesondalen. they have a superficial similar ity to kettles formed by melting of buried ice. however, several of the depressions contain a drainage into underlying gypsiferous beds. they sj location m a p fig. 1. location map. 83 84 0. saluigsen, 0. lauritzen & j . mangerud can therefore generally be characterized as sink holes (dolines) with associated forms. six such depressions (locs. 1-6, fig. 2 ) are described, including apparent fossil sinkholes and present day active sinkholes. these are: (1) the highest lying depression, about 70 metres above sea level, is a lake on the beach terrace on the south side of the valley, near the talus. this appears to be a fossil sinkhole. the total diameter is about 100 metres, and surplus of water is drained by a surface stream. in late summer-time the pond usually has no visible drainage. here, the bedrock is not exposed. ( 2 ) a small circular sinkhole pond is found on the terrace north of the river bed (fig. 3). the height of the terrace is about 35 metres above sea level, and the sinkhole is probably a fossil one. the pond has no visible outlets, and the water depth varies throughout the year. bedrock was fig. 2. vertical air photograph of the mathiesondalen area. kapp ekholm in the foreground. the numbers refer to the karst depressions described in the text as localities i to 6. photo. not exposed. norsk polarinstitutt s61 2959 ( 2 3 august 1961). (3) the lowest lying depression is located in the fig 3 . locality 2 . the small sinkhole pond without any surface outlet. figure in foreground as scale karstijcation in gypsiferous beds, svalbard 85 through it and disappears into a swallow hole in a highly jointed and collapsed gypsiferous wall (fig. 4) at a level of about 4 metres below the pond level. the cave probably has a connection to the lake previously mentioned (locality 4). this underground outlet has also been observed by river fan system of kapp ekholm about 6 metres above sea level. a small stream flows into the pond, and the outlet is near the inlet. no differ ence between inflow and outflow could be seen. the walls of the depression show evidence of fresh slides in unconsolidated material. bedrock was not exposed. balchin (1941). (4) a lake near the southern edge of the delta plain is remarkable. it has a length of about 300 metres and seems to have a considerable depth. the lake is about 6 metres above sea level, and the southern side has fresh slides in terrace sand and gravel. in late july the outlet of the lake was a rapid flowing stream, which was difficult to cross in rubber boots. obvious sources of water were not apparent and there were no streams running into the lake. we conclude that the lake must be fed by subterranean tributaries, arising partly from the sinkholes and swallow holes observed in depressions at localities 5 and 6. (5) a small sinkhole pond is found about 32 metres above sea level, 300 metres east of the described lake (locality 4). a small stream flows (6) a jointed and collapsed bedrock in locality 5 continues to the end of a short blind valley which branches out from the main river plain (figs. 5 & 6). water from the main river in mathiesondalen feeds a shallow lake in the blind valley. the supply of water is highly variable, and in the summer of 1981 it was small because the main river was on the opposite side of the river plain. in 1981 the water level in the lake varied with the precipitation. following heavy rainfall the water level rose about 25 cm, and shore marks showed the level t o have been approximately one meter higher than normal (see fig. 5). at this level the blind valley will be filled with water, and surface drainage will start to the river plain of mathiesondalen. this maximum level had prob ably been reached in the snow melting period. in fig. 4. locality 5. the swallow hole with stream flowing from left into the base of the white, tilted gypsiferous beds and disappearing into the open fractures. figure in the upper right corner as scale. 86 0. saloigsen, 0. lauritzen & j . mangerud fig. 5 . locality 6. the lake of the blind valley. photo taken towards southwest. the outlet into fractured gypsiferous beds is seen on the opposite shore of the lake (see also fig. 6). note the shore marks of hlgher lake icvels. figure on shore as scale. late july a great part of the blind valley was a lacustrine plain covered by fine sediment. t h e lake was drained by subterranean outlets in the blind valley. t h e bedrock is highly jointed and several collapsed tunnels can be seen (fig. 6). in many places the rock surface has small scale sol ution features, and newly collapsed tunnels also show that karst processes a r e still active. o n e small scale stream from the main river plain was also observed t o disappear before it reached the pond. it disappeared in a 5 metre wide and 2 metre high tunnel in unconsolidated material near the edge of the river plain. during a time span of two weeks, about 10 metres of the tunnel collapsed. but this did not affect the out flow of t h e stream. n o bedrock was seen in the tunnel. t h e subsurface drainage from this area probably ends in t h e lake here described as local ity 4. discussion and conclusion at localities 5 and 6, water can be observed flowing into caves in the g y p s u d a n h y d r i t e beds, the o n e at locality 6 being a 5-6 metre deep collapsed cave. it is therefore obvious that most (probably all) of these described depressions are real karst forms, here developed by the solution of gypsum/anhydrite. their slopes, however, a r e moulded by thermokarstic processes in the over lying sediments. t h e sinkholes occur in uplifted beach sediments which subside into t h e depressions. both the structures and the surface forms of the beach sediments are crosscut by sinkholes (see fig. 2). we have n o observations of fossil sinkholes o r cracks in t h e bedrock filled with till. two main conclusions can b e drawn from these observations: (1) t h e sinkholes a r e mainly formed by collapse of subsurface caves. w h e r e the active permafrost reaches t h e bedrock, downward solution may also have taken place. (2) t h e sinkholes a r e younger than the beach sediments in which they occur. t h e caves and tunnels from which the sinkholes were formed karstif cation in gypsiferous beds, svalbard 87 fig. 6. locality 6. a collapsed gypsum cave near the subter ranean outlet of the lake of the blind valley (see also fig. 5). figure above cave as scale. may be older, but they have collapsed after the formation of the strandlines. the strandlines have been formed more or less continuously from approximately 11,000 years b.p. until the present (feyling-hanssen 1965), and thus all sinkholes are of holocene age. the observed present activity i n the sinkholes is also indicative of a young age. the svalbard area is subject to perrriafrost, and a normal model for groundwater circulation can not be used. the permafrost layer normally acts as a very efficient barrier to groundwater per colation. in the described area the active layer however, a crucial factor in this connection is that the subsurface consists of soluble evaporite minerals in a highly jointed bedrock. freeze-thaw action in bedrock cracks may allow water circu lation in the rock and cause solution. liestd (1977) has discussed the flow of water in permafrost areas and shown that even narrow passages are held open all the year round in connection with pingos and springs. the water flow in mathiesondalen, however, ceases during the autumn, and subsurface waterflow will be at a minimum until spring melting starts. then per colation in the gypsiferous beds can start, causing the development of karst forms. gypsum or other evaporite rock fragments are hardly ever seen in the quaternary sediments, except in the screes where they are very locally derived, and even here the process of disintegra tion seems more active to the evaporites than to the interbedded rocks, mostly dolomites. the rate of solution of large gypsum blocks has been stud ied elsewhere, e.g. from permian beds in england (james, cooper & holliday 1981), and factors like water flow velocity, temperature, etc. have been considered. here, however, we will not try to calculate the rate of solution or the time involved in the dissolution processes but will rather stress the fact that these processes are active in high arctic areas where snow and ice cover the ground most of the year. acknowledgements. we thank dr. david l . bruton for improving the english text, carl e. dons and yngve m . nilsen for assistance in the field, and espen kopperud for preparing the figures for the press. references balchin, w. g. v. 1941: the raised features of billefjorden and sassenfjorden, west spitsbergen. g e o g r . j . x c v i i . no. 6, 364-376. corbel, j . 1957: lcs karst du nord-oust de i’europe. inst. etudes rhondaniennes de i’universite dc lyon, m e m . er doc. i . 544 pp. corbel, j . 1960: nouvelles recherches sur les karst arctiques scandinaves. z . g e o m o r p h . n . f . s u p p . 2 , 74-78. cutbill. j. l. & challinor, a . 1965: a revision of the strati graphical scheme for the carboniferous and permian rocks of spitsbergen and bjmnoya. geol. mug. 102. 418-439. feyling-hanssen, r . w. 1955: stratigraphy of the marine has a maximum thickness of 2 metres; the late-pleistocene of billefjorden, vestspitsbergen. n o r . described subsurface drainage is well below this, feyling-hanssen, r . w. 1965: shoreline displacement in central cult to understand how water can penetrate and keep an open passage through the frozen layer. s k r . n r . lo7, lg6 pp, and thus in permanently ground‘ it is diffivestspitsbergen, n o r , polarinst, nr, 93, 1-5, gee, e . r . , harland, w. b . & mcwhae, j. r. h. 1953: geology of central vestspitsbergen: part i . review of the geology of 88 0. saluigsen, 8. lauritzen & j . mangerud spitsbergen with special reference to central vestspitsher gen. tram. royal soc. edinb. l x i i . part 11. harland, w. b . , cutbill, j . l., friend, p. f.. gobbett. d j . , holliday, d . w.. maton. p. 1.. parker, j . r. & wallis r h. 1974: the billefjorden fault zone, spitsbergen. nor. polar ins! skr. nr 161. 72 pp. hellden. u. 1974: some calculations of the dcnudation in a dolomitic limestone area at isfjord-radio. west-spitsbergen. nor. geogr. tidsskr. 28. 8s-88. holliday. d . w . & cutbill. j . l. 1972: the ebhadalen for mation (carboniferous). spitsbergen. proc. yorks. geo. s o c . 39. pi. 3 (16). 277-292. james. a . n . . cooper. a. h . & holliday. d w . 1981: solution of the gypsum cliff (permian, middle marl) by the r h e r ure at ripon parks. north yorkshire. proc. yorks. geol. s o c . 43, pt. 4 (24). 4 3 s 4 5 0 . johannessen, e. 1980: fasies pnalyse nu ebbadalen formasjo nen, mellomkarbon, billeflorden trau, spitsbergen. unpubl. thesis, univ. of bergen. lauritzen, 8. & salvigsen, 0. 1983: holocene sedimentary rocks in mathiesondalen, central spitsbergen, svalbard. polar research i n . s . , in press. liestel, 0. 1977: pingos, springs and permafrost in spitsbergen. nor. polarinst. h b o k 1975, 7-29. orvin, a . 1944: litt om kilder p i svalbard. nor. geogr. tidsskr. x , 1 6 3 8 . sweeting, m. m. 1968: karst, pp. 582-587 in fairbridge, r. w. (ed.), encyclopedia geomorphology, reinhold book corporation, n.y. 1295 pp. por_018.fm 210 polar research 26 2007 210 – 211 © 2007 the author b o o k r e v i e w review of boreal ties. photographs and two diaries of the 1901 peary relief expedition , edited by kim fairley gillis and silas hibbard ayer iii (2002). albuquerque: university of new mexico press. 232 pp. isbn 0826328105. in boreal ties , the famously crusty and imperious robert peary is referred to as “a peach“. at first this representation might appear to be flagrantly inaccurate, somewhat like calling dr frederick cook—peary’s not always truthful north pole adversary—“a bastion of honesty”. but within the context of the book, the description is wholly apt. in the early years of the 20th century, the peary arctic club was the explorer’s financial lifeline. the club’s members, who were mostly wealthy businessmen, donated money and provisions for peary’s arctic sojourns, in return for which the explorer peppered various geographical features with their names. on one occasion, however, the club donated two of its members to the peary cause. having paid the then not inconsiderable sum of $500 apiece, clarence wyckoff and louis bement— two affluent young men from new york—joined the 1901 peary relief expedition and sailed north on the steamer erik , accompanied by, among others, dr cook himself. the purpose of the expedition was to locate peary and attend to his medical needs (cook’s job), as well as to resupply him for his seemingly endless assaults on the pole. the text of boreal ties consists primarily of wyckoff and bement’s diaries of the trip. written casually (colloquialisms like “peach” abound), these diaries show two privileged young men engaged in a sort of offbeat holiday. not surprisingly, the two men’s responses to what they experience tend to be conditioned by their backgrounds. thus, wyckoff writes: “halifax bum town like kingston and most canuck towns. bum hotel, bum everything” (p. 45). their attitude to the greenland inuit, whom they call huskies, is more or less typical for the time: frequently condescending or racist. bement compares the eagerness of the inuit when receiving gifts to “the feeding of chickens” (p. 86). of their personal hygiene, he writes: “i did not suppose human beings could live and stink so . . .” (p. 75) and “. . . it must be worse than a dog’s life they lead” (p. 113). of an apparently too proud young inuk, wyckoff says: “jollied him into carrying [my] bag back to ship . . . and think it did him good” (p. 157). he does not record what the inuk thought of this “jollying”. amid such observations peary himself plays only a subsidiary role, perhaps because he is less than forthcoming about his discoveries or lack thereof. upon meeting him, wyckoff grumbles: “. . . we got no news . . . all is very secret . . . think it is damn rotten that i was left out of everything” (p. 127). cook, by contrast, is at least sociable, although he doesn’t talk much about his polar exploits either. the result is that the diaries do not provide a window on arctic exploration, so much as give voice to the sensibilities of a pair of greenhorns venturing into the arctic for the first time. in addition to keeping diaries, the two men took photographs, a number of which are reproduced in the book. although many of these photographs are set up like studio portraits, many others seem to be taken on a whim. thus we see dr cook washing himself on the deck of the erik , crewmen playing chess, and peary checking an inuit woman for head lice. in spite of this, or perhaps because these photographs were not taken by professionals correspondence lawrence millman po box 381582, cambridge, massachusetts, ma 02238, usa. e-mail: l.millman@comcast.net book review polar research 26 2007 210 – 211 © 2007 the author 211 (several are in fact overexposed), they have a genuine documentary value. caught at random moments, peary appears to be in poor physical health, a fact that he himself denied. and a picture of four crew members taking their leisure during a caribou hunt also includes their inuit guide seated in the background, a depiction of the local status at once dramatic and unintentional. the images of the greenlanders are especially revealing, for wyckoff and bement are obliged to capture what they’re actually seeing, rather than what their prejudices tell them they’re seeing. in other words, an inuk’s putative smell does not take priority over his sealskin garments or dignified gaze. an inuit camp with a heap of rocks extending across the foreground, and steep snowy slopes in the background, suggests a subsistence carved out of a harsh environment using great human ingenuity, rather than “a dog’s life”. likewise, an inuit child looks at the camera with a wry grin, as if to say: “white men have such peculiar toys”. the child is dirty and disshevelled, but that’s not significant. what is significant is that the child isn’t inured to having her picture taken, and at the same time isn’t astonished by the idea of photography. however dubious peary’s claims to the pole were, his charisma and flair for self-promotion put the arctic firmly in the public consciousness during the early years of the 20th century. in turn, this led to discoveries arguably more important than any peary made himself. the 1901 peary relief expedition accomplished little beyond its original goals, although the two young men who participated in it did discover—at least temporarily—that there’s more to life than the comforts of home. handsomely produced, but less than handsomely edited (among other errors, “deer” is indeed a synonym for caribou), boreal ties is a testimony to this fact. doi:10.3402/polar.v32i0.19136 r e s e a r c h / r e v i e w a r t i c l e reactive nitrogen and sulphate wet deposition at zeppelin station, ny-ålesund, svalbard rafael kühnel,1,2 mats p. björkman,1,2 carmen p. vega,3 andy hodson,4 elisabeth isaksson1 & johan ström 5 1 norwegian polar institute, fram centre, no-9296 tromsø, norway 2 department of geosciences, faculty of mathematics and natural sciences, oslo university, p.o. box 1032, blindern, no-0315 oslo, norway 3 department of earth sciences, uppsala university, villavägen 16, se-75236 uppsala, sweden 4 department of geography, university of sheffield, sheffield s10 2tn, uk 5 department of applied environmental science, stockholm university, svante arrhenius väg 8, se-11418 stockholm, sweden keywords nitrogen; sulphur; arctic; precipitation; sampling; nsink. correspondence rafael kühnel, norwegian polar institute, fram centre, no-9296 tromsø, norway. e-mail: rafael.kuhnel@npolar.no abstract as a potent fertilizer, reactive nitrogen plays an important role in arctic ecosystems. since the arctic is a nutrient-limited environment, changes in nitrogen deposition can have severe impacts on local ecosystems. to quantify the amount of nitrogen deposited through snow and rain events, precipitation sampling was performed at zeppelin station, svalbard, from november 2009 until may 2011. the samples were analysed for no � 3 ; nss-so 2� 4 and nh � 4 concentrations, and the deposition of single precipitation events was calculated using precipitation measurements taken at nearby ny-ålesund. the majority of observed events showed concentrations ranging from 0.01 to 0.1 mg l �1 n for no � 3 and nh � 4 and from 0.02 to 0.3 mg l �1 s for nss-so 2� 4 : the majority of calculated depositions ranged from 0.01 to 0.1 mg m �2 n for no � 3 and nh � 4 and from 0.02 to 0.3 mg m �2 s for nss-so 2� 4 : the budget was controlled by strong deposition events, caused by long-lasting precipitation episodes that lasted for several days and which had raised concentrations of nitrogen and sulphur. three future scenarios of increasing precipitation in the arctic were considered. the results showed that deposition is mainly controlled by the amount of precipitation, which leads to the conclusion that increased precipitation might cause increases in deposition of the same magnitude. research on arctic air pollution during the second half of the last century, motivated by the observation of the arctic haze phenomenon in the canadian arctic, revealed that the arctic is not as pristine as formerly assumed, but rather is influenced by mid-latitude atmospheric pollution through long-range transport (rahn 1981, 1985; raatz 1984; barrie 1986; ottar et al. 1986; cheng et al. 1993; shaw 1995). this pollution generally consists of a mixture of so 2� 4 ; nh � 4 ; no � 3 and black carbon (dickerson 1985; beine et al. 1996; quinn et al. 2002; quinn et al. 2007). no � 3 and nh � 4 play a special role since they act as effective nutrients for arctic ecosystems (shaver & chapin 1980). reactive forms of nitrogen, such as nox (no�no2) and nh3, are released by natural and anthropogenic sources. in today’s industrialized world, anthropogenic sources*primarily food, fertilizer and energy production*are the most important sources of reactive nitrogen (galloway et al. 1995; galloway et al. 2004; grice et al. 2009). the reactive nitrogen is transported to the arctic in the form of peroxyacetyl nitrate (pan), no � 3 and nh � 4 aerosol (dickerson 1985). it is finally removed from the atmosphere and transferred to the arctic surface through wet or dry deposition; wet deposition is believed to be the main pathway (bergin et al. 1995). ice core analyses from greenland and svalbard show increasing no � 3 concentrations in the 1950s followed by a decrease in the 1980s (isaksson et al. 2003; hastings et al. 2009; samyn et al. 2012). concentrations in arctic (page number not for citation purpose) polar research 2013. # 2013 r. kühnel et al. this is an open-access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 precipitation for the period from 1980 to the present show no significant trends for no � 3 ; but a decreasing trend for so 2� 4 (hole et al. 2009; aas et al. 2011). mitigation programmes and improvements in technology have led to reduced emissions in europe in the last decade (erisman et al. 2003) and european and north american nitrogen emissions are expected to decrease further as a result of future legislations. it is, however, possible that the decrease in sea-ice cover could lead to an intensification of shipping activity that would increase emissions within the arctic (peters et al. 2011). the mean annual nitrogen deposition in ny-ålesund, svalbard, by no � 3 and nh � 4 during the last two decades was about 74 mg m �2 n and showed a strong interannual variability caused by a few sporadic but strong deposition events (kühnel et al. 2011). for a comparison, the average deposition at 95 european sites was 550 mg m �2 n in 2009 (hjellbrekke & fjæraa 2011). see monks et al. (2009) and sutton et al. (2011) for background information on nitrogen in the environment. the transport of nitrogen is linked to the transport of sulphur through the following chemical reactions: 2nh3(g)�h2so4(g) 0 (nh4)2so4(s); (r1) nh3(g)�h2so4(g) 0 nh4hso4(s): (r2) here, g and s indicate the gaseous and particulate phase. the reactions show the neutralization of ammonia by sulphuric acid to ammonium sulphate particles. remaining ammonia molecules might then be neutralized by nitric acid to form ammonium nitrate by this reaction: nh3(g)�hno3(g) l nh4no3(s): (r3) for further details on these processes, the reader is referred to seinfeld and pandis (2006). as a result of reduced sulphur emissions in recent decades, the chemical transformation of nitrogen may have shifted towards the formation of ammonium nitrate (fagerli & aas 2008). since the typical lifetimes of nitric acid and ammonium nitrate are different, the reduction in sulphur emissions might have an impact on the lifetime of no3 in the air by shifting the balance to reaction r3. it has been estimated from model runs that no3-x in air over the european continent increased by 15�30% in the period from 1990 to 2003 (fagerli & aas 2008). how these nonlinearities in the atmospheric chemistry impact nitrogen deposition is unclear. the arctic winter atmosphere is characterized by high stability, which inhibits vertical exchanges between airmass layers and reduces chemical reactions. photochemical processes are also inhibited in wintertime due to the lack of sunlight. both effects lead to longer lifetimes of chemical species in polluted air masses in the arctic during winter, so pollution can be transported over longer distances once they reach the arctic (barrie 1986; shaw 1995). it has been suggested that the transport of contaminants into the arctic is isentropic, i.e., the air parcels follow surfaces of constant potential temperature (iversen 1984; klonecki et al. 2003). isentropic surfaces build a dome over the arctic with minimum temperatures in the arctic boundary layer. the regions where the isentropic surfaces intercept the ground and where there are strong horizontal gradients of potential temperature are referred to as the polar front, which forms an effective transport barrier (klonecki et al. 2003). the position of the polar front varies seasonally. during the winter, it is located further south so that parts of the northern eurasian continent are situated north of it (barrie 1986). in addition, diabatic cooling of air masses over the snowcovered landmasses of northern eurasia make the arctic more susceptible to mid-latitude pollution during the winter months (stohl 2006). during summer, the polar front is situated further north, separating mid-latitudes from the arctic. air is mixed vertically due to heating over mid-latitude landmasses and air masses that are transported northwards are forced to ascend along isentropic surfaces. it is assumed that these air masses are scavenged of pollutants during their ascent before they might enter the arctic by subsidence (stohl 2006). surges of eurasian air masses can occur during situations with strong east� west pressure gradients. an example of this is a strong blocking high pressure system over the eurasian continent and an icelandic low, which results in poleward transport between these two pressure centres (raatz & shaw 1984; iversen & joranger 1985). it seems that strong nitrogen wet deposition in svalbard is caused by such surges of eurasian air masses (kühnel et al. unpubl. ms.). in general, the arctic is characterized by low precipitation on account of its stable atmospheric stratification and low water vapour content (due to low temperatures). the long-term mean annual precipitation for the period 1957�1990 over the arctic ocean, as observed at drift stations, was 260 mm, with a distinct seasonal cycle that has maximum values in autumn and winter (yang 1999). the annual precipitation in svalbard in the period from 1960 to 1990 ranged from 190 to 525 mm, with the highest precipitation in march and august to october (førland et al. 1997). precipitation in the arctic can occur as snow or rain throughout the year. precipitation observations are in general difficult in the arctic due to high wind speeds and drift snow (krupa 2002). for ny-ålesund, svalbard, it has been estimated that true precipitation might be 50% higher than the uncorrected reactive nitrogen and sulphate wet deposition, svalbard r. kühnel et al. 2 (page number not for citation purpose) citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 observations using standard collection methods (hansenbauer et al. 1996). atmospheric nitrogen, like no � 3 and nh � 4 ; is to a large extent scavenged by snow during winter and thereby accumulates in the snowpack, where it can undergo photochemical reactions (beine et al. 2003; grannas et al. 2007) that might alter the chemical composition of the snowpack. the nitrogen is released in spring during snowmelt and can then act as a fertilizer to local ecosystems (shaver & chapin 1980; arens et al. 2008). atmospheric nitrogen that is scavenged by rain during summer is immediately available to ecosystems. the arctic is a nutrient-limited region, especially for nitrogen and phosphorus (shaver & chapin 1980). it is therefore sensitive to changes in nitrogen deposition (gordon et al. 2001; arens et al. 2008; roberts et al. 2010). phosphorus availability limits the effects of additional nitrogen deposition, as has been shown by studies in the high arctic that found that ecosystems were able to take up more nitrogen where phosphorus availability was greater (gordon et al. 2001; arens et al. 2008). glaciers cover a significant proportion of the landscape in svalbard so nitrogen deposition and transfer through glacier ice is an important process prior to its liberation to nutrient-limited ecosystems at the ice margin. however, microbial assimilation on the surface of glaciers is now known to be a key feature in the annual mass balance of nitrogen in the study area (hodson et al. 2005; hodson et al. 2008). until this biological demand is properly understood, the impact of glacier mass balance change upon the timing, magnitude and composition of reactive nitrogen liberation to downstream ecosystems cannot be estimated from ice core and emission inventories. most of the precipitation on svalbard is connected to cyclonic activity (eneroth et al. 2003). model studies predict an increase in the frequency of intense cyclones in the north atlantic storm tracks. annual net precipitation is predicted to increase by 20% over the arctic cap, where the majority of the increase is caused by changes in atmospheric thermodynamic and precipitation physics. changes in the moisture content of the atmosphere were suggested as a primary factor affecting the thermodynamic properties of the atmosphere (cassano et al. 2006; cassano et al. 2007). another model study suggested that the absolute increase in winter precipitation will be highest over the atlantic storm tracks and that the regions of high precipitation will extend further to the north (saha et al. 2006). observations by førland et al. (1997) indicate an increase of annual precipitation in svalbard of 25�30% during the past 85 years. however, the cause of this trend is unclear. since precipitation is a major driver of nitrogen deposition, the increase in cyclonic activity and precipitation might lead to stronger deposition events in svalbard (kühnel et al. 2011). it is therefore necessary to gain further insight into the nature of nitrogen deposition at such a sensitive site. on behalf of the norwegian climate and pollution agency, the chemical composition of precipitation in ny-ålesund, svalbard, has been analysed by the norwegian institute for air research in collaboration with the norwegian polar institute since 1980 (fagerli & aas 2008; aas et al. 2011). a detailed study of this data set with respect to nitrogen and sulphur compounds can be found in kühnel et al. (2011). precipitation samples taken at alert, canada, for the period from 1990 to 1994 were analysed by toomsauntry and barrie (2002). however, both programmes have sampling periods of about a week, which is longer than the timescale of typical precipitation events. this makes it difficult to characterize the chemical signature of single precipitation events. in addition, synoptic weather patterns might change substantially within one sampling period. this further complicates the study of pollution transport in connection with the deposition observations. studies with event based precipitation sampling have been conducted in svalbard but covered short time periods of several weeks to a few months (kang et al. 2001; krawczyk et al. 2008). this study presents concentration observations of no � 3 ; nh � 4 and so 2� 4 with near to daily sampling that permits the analysis of single deposition events. precipitation was sampled at zeppelin station near ny-ålesund, svalbard, from 4 november 2009 to 19 may 2011. the sampling campaign was part of the collaborative, interdisciplinary project sources, sinks and impacts of atmospheric nitrogen deposition in the arctic. atmospheric sciences, snow physics, hydrology, biogeochemistry and aquatic/terrestrial ecology were integrated in this project that intended to give a detailed picture of nitrogen dynamics and to track the fate of reactive nitrogen in the arctic. methods sampling the sampling campaign started on 4 november 2009 and continued until 19 may 2011. precipitation was sampled at zeppelin station (78.908n, 11.888e), at an altitude of 474 m a.s.l. (fig. 1). the samplers used in this study were an open bucket-system from 4 november 2009 to 6 may 2010 and 31 august 2010 to 19 may 2011, and a r. kühnel et al. reactive nitrogen and sulphate wet deposition, svalbard citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 funnel-bottle system from 6 may 2010 to 1 september 2010 (fig. 2). the bucket system utilized a container with an opening diameter of 30 cm mounted on a wooden rail outside zeppelin station. polyethylene plastic bags were fitted inside the bucket for sampling and secured with a strong rubber strap around the outside of the bucket. the bucket was fitted with a valve and a vacuum pump was used to evacuate the space between bucket and plastic bag to keep the bag in place. the funnel-bottle system consisted of a polyethylene plastic funnel with an opening of 20 cm. high-density polyethylene bottles (250 ml) were fitted under the funnel for sampling. the funnel was rinsed with ultrapure water between each sampling. two different samplers were used for optimal performance during different precipitation conditions. fig. 1 maps of kongsfjorden and ny-ålesund. fig. 2 bucket sampler for solid precipitation (left) and funnel sampler for liquid precipitation (right). reactive nitrogen and sulphate wet deposition, svalbard r. kühnel et al. 4 (page number not for citation purpose) citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 the bucket sampler had a wider opening for efficient snow sampling. designed for sampling liquid precipitation, the funnel-bottle system used a bottle with a narrow opening that limited loss through evaporation and possible contamination by blown dust. the samplers were maintained by staff from the norwegian polar institute during their routine maintenance at zeppelin station on weekdays. during weekends and bad weather conditions the station was not attended and samples were retrieved during the next visit to the station. precipitation samples taken in both plastic bags and bottles were stored frozen and in the dark until further preparations for analysis were performed. the preparations included melting of the samples at room temperature and vacuum filtering on cellulose nitrate filters with 0.45 mm pore sizes. after filtration the samples were bottled and kept frozen until ion chromatographic analysis took place in sheffield, uk, or uppsala, sweden. the equipment was triple rinsed with ultrapure water and blanks were analysed along with the samples to identify possible baseline noise values. ion chromatography analysis the samples were analysed for major ions (na � , ca �2 , mg �2 , nh � 4 ; f � , cl � , br � , no � 3 ; so 2� 4 and ox 2� ) at the department of geography, university of sheffield, uk, and at the university of uppsala, sweden. analysis at the university of sheffield was performed on 5 ml samples using two dionex dx 90 ion chromatographs (thermo fisher scientific, waltham, ma, usa) with 4400 integrators and as40 auto-samplers (thermo fisher scientific) with a 0.2 mm nucleporetm prefilter (whatman, maidstone, kent, uk) and a six standard calibration range between 0 to 2000 mg/l that was run at least once every 20 samples. precision errors of less than 5% were also estimated from 10 replicate analyses of a single snow sample. a detection limit of 1 mg/l was imposed for all analyses using chromeleon software. this was never exceeded by results for laboratory blanks, which were prepared using the 18 o ohm water supply and analysed once every 10 samples. analysis at the university of uppsala was performed on 5 ml samples using a profic850 ion chromatographer (metrohm, herisau, switzerland). a calibration range from 1 ppb (mg/l) to 1000 ppb (mg/l) was employed using 12 calibration points. the regression coefficients for each calibration curve were in the range of 0.9998� 0.9999. three sample blanks made of ultrapure water were measured at the beginning and end of every analysis batch and sample checks made of melted bulk snow were analysed every 10 samples to ensure the continuity of the analysed samples. the detection limits (dls) for each ion were calculated as the average value of six ultrapure blanks plus 1.65 times the standard deviation of the six measurements (dl �blankaverage�1.65 � blankstandar deviation), which results in concentrations in the samples having to be higher than the concentrations in the ultrapure water at the 0.05 significance level to be valid. the dls were below 5 ppb for all ions. a minimum of 5 ml per sample was required, and so lower volumes were diluted using ultrapure water (18 v) to a final volume of 5 ml. the result of these lower volumes was corrected for dilution afterwards. correction of so4 2� for sea-salt component the observed total so 2� 4 was corrected for its sea-salt component using: [nss�so2�4 ]�[so 2 4]� � [so2�4 ] [na�] � sea-salt �[na�] (1) where nss-so 2� 4 is the concentration of non-sea-salt sulphate, so 2� 4 is the total sulphate observed and na � is the observed concentration of sodium (kärkäs et al. 2005). the mass concentration ratio of so 2� 4 to na � in sea-salt was set to 0.252 (millero et al. 2008). calculation of deposition the precipitation samplers were placed at zeppelin station to limit the influence of local contamination from the settlement of ny-ålesund. the samplers had the sole purpose of collecting precipitation for chemical analysis and have not been tested or calibrated for measurements of precipitation quantity. since no official precipitation observations are performed at zeppelin station, the norwegian meteorological institute’s measurements of precipitation amount at ny-ålesund were used, along with the concentration observations from zeppelin station, for the calculation of nitrogen and sulphur deposition. the precipitation observations at nyålesund are conducted twice daily, at 07:00 and 19:00, by norwegian polar institute staff on behalf of the norwegian meteorological institute’s routine weather observations. deposition of no � 3 ; nh � 4 and nss-so 2� 4 was calculated by multiplying the observed precipitation amount with the observed concentrations of the same time. due to dissimilar starting and ending times of the concentration and precipitation sampling, it was possible that precipitation observations were covered by more than one concentration observation. precipitation observations that were covered by several concentration r. kühnel et al. reactive nitrogen and sulphate wet deposition, svalbard citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 observations were therefore fractionated into observations with shorter timescales that fit the time periods of the concentration observations. it was assumed that the precipitation rate was constant during each precipitation observation. deposition events consecutive, non-interrupted precipitation/deposition observations were merged to single observations, which are hereafter referred to as events. for our purposes, an event is defined as a precipitation period starting from the start time of the first nonzero precipitation observation until the start time of next first zero precipitation observation. due to the precipitation sampling interval, the shortest precipitation/deposition events recognizable in this study had durations of 12 h. furthermore, one or several precipitation periods of timescales less than 12 h falling within one observation period would be registered as a single precipitation event. an event was considered isolated if it shared no concentration observations with other events. an event was considered complete if all of its precipitation observations were covered by concentrations observations. for each event the average concentration of no � 3 ; nh � 4 and nss-so 2� 4 was calculated, that is, the deposited mass of no � 3 ; nh � 4 or nss-so 2� 4 divided by the total mass of precipitation. cumulative distribution functions were calculated for the number densities and mass densities, for the event average concentrations and the event deposition magnitude. a linear regression analysis of event average concentrations versus precipitation amount, as well as event deposition magnitude versus precipitation amount was then performed. future scenarios facing projections of increasing precipitation over the arctic (cassano et al. 2007), three scenarios of future nitrogen and sulphur deposition were considered. the events were divided into two subgroups by arbitrarily choosing the 75th percentile of the precipitation across all the events*4.4 mm*as the dividing line. group a consisted of events with 4.4 mm of precipitation or less while group b comprised events with precipitation exceeding 4.4 mm. sensitivity tests were also carried out when dividing the events at the 50th and 90th percentiles. the data from these tests are not presented in this manuscript, but will be touched upon briefly in the discussion below. the mean of the event average concentrations was calculated for both groups. in scenario i, the precipitation amounts of all events increased by 20%; in scenario ii, only the precipitation amounts of group a increased by 20%; in scenario iii, only the precipitation amounts of group b increased by 20%. in the control scenario the quantity of the precipitation was not increased in any of the groups. the average concentrations of the groups were then multiplied by the precipitation amount of the events to give the event deposition. the total deposition was calculated by summing over all events. finally, the total deposition amounts of all three scenarios were compared to the total deposition of the control scenario. results a total of 313 precipitation observations were made during the sampling campaign by the norwegian meteorological institute. the number of precipitation observations covered with concentration observations from zeppelin mountain is 260 (83%) for no � 3 ; 257 (82%) for nss-so 2� 4 and 263 (84%) for nh � 4 : the total number of precipitation/deposition events, as defined in the previous section, is 125. the events had a median duration of 1.25 days. the longest precipitation event during the sampling campaign lasted for 7 days. the median amount of precipitation of all events was 1.5 mm; the largest precipitation event was 89.6 mm. the number of isolated precipitation events was 62 (49.6%). the number of complete deposition events was 96 (76.8%) for no � 3 ; 94 (75.2%) for nss-so 2� 4 and 99 (79.2%) for nh � 4 : a monthly overview of precipitation events and the number of reconstructed deposition events are presented in table 1. figure 3 shows the cumulative distribution function of the event average concentrations of only isolated and complete events. the majority of event average concentrations of no � 3 and nh � 4 were in the range between 0.01 and 0.1 mg l �1 n, with a median of 0.02 mg l �1 n (fig. 3). the majority of the event average concentrations of nss-so 2� 4 were somewhat higher, lying in the range of 0.02�0.3 mg l�1 s, with a median of 0.08 mg l�1 s (fig. 3). the mass distributions show that approximately half of the deposited mass of nitrogen through no � 3 was associated with events that had average concentrations greater than 0.1 mg l �1 n. half of the deposited mass of nitrogen through nh � 4 was associated with event average concentrations greater than 0.05 mg l �1 n. half of the deposited nss-sulphur was associated with event average concentrations of greater than approximately 0.3 mg l �1 s. the average concentration during 2010, calculated as the ratio of total deposition amount to total precipitation amount, for no � 3 ; nh � 4 and nss-so 2� 4 was reactive nitrogen and sulphate wet deposition, svalbard r. kühnel et al. 6 (page number not for citation purpose) citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 0.05 mg l �1 n, 0.02 mg l �1 n and 0.1 mg l �1 s, respectively. the cumulative distribution functions of the deposition event sizes of only the isolated and complete events are shown in fig. 4. the bulk of events show deposition of no � 3 and nh � 4 between 0.01 and 0.1 mg m �2 n, with a median of 0.02 mg m �2 n. for nss-so 2� 4 ; the bulk of events was in the range of 0.02� 0.3 mg m�2 s, with a median of 0.09 mg m �2 s. similar to the event average concentrations, the majority of deposited mass was associated with large deposition event sizes. for no � 3 ; nh � 4 and nss-so 2� 4 ; half of the deposited mass was associated with events greater than 2 mg m �2 n, 0.6 mg m �2 n and 2 mg m �2 s, respectively. table 1 number of precipitation events during sampling campaign, number of reconstructed deposition events (percentage of precipitation events reconstructed) and number of complete and isolated deposition events (percentage of isolated and complete deposition events). a single asterisk marks no�3 events and double asterisks mark nss-so 2� 4 and nh � 4 events. reconstructed deposition events month precipitation events total number complete and isolated nov 2009 6 4 (67%) 2 (33%) dec 2009 9 5 (56%) 0 (0%) jan 2010 9 5 (56%) 1 (11%) feb 2010 2 1 (50%) 1 (50%) mar 2010 6 4 (67%) 3 (50%) apr 2010 6 5 (83%) 5 (83%) may 2010 5 5 (100%) 3 (60%) jun 2010 5 3 (60%) 3 (60%) jul 2010 6 5 (83%) 1 (17%) aug 2010 7 *5 (71%), **3 (43%) *1 (14%), **0 (0%) sep 2010 10 5 (50%) 4 (40%) oct 2010 8 8 (100%) 4 (50%) nov 2010 8 8 (100%) 4 (50%) dec 2010 9 8 (89%) 4 (44%) jan 2011 7 5 (71%) 5 (71%) feb 2011 4 4 (100%) 2 (50%) mar 2011 6 4 (67%) 2 (33%) apr 2011 8 8 (100%) 7 (88%) may 2011 4 4 (100%) 1 (25%) 0.0001 0.001 0.01 0.1 1 10 0 0.2 0.4 0.6 0.8 1 event average concentration (mg/l n resp. mg/l s) c u m u la tiv e d is tr ib u tio n f u n ct io n no3 no3 nss−so4 nss−so4 nh4 nh4 − number 2− number + number − mass 2− mass + mass fig. 3 cumulative distribution function of number and mass distributions of no�3 -, nss-so 2� 4 and nh � 4 -concentration. r. kühnel et al. reactive nitrogen and sulphate wet deposition, svalbard citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 an overview of the precipitation amount and event average concentrations of all events during the sampling campaign can be seen in fig. 5. most of the events show a precipitation amount of less than 5 mm. these events can be found throughout the sampling campaign. larger events seem to be missing in the summer (june� september) 2010. the four largest events had precipitation amounts exceeding 50 mm and occur during 0.0001 0.001 0.01 0.1 1 10 0 0.2 0.4 0.6 0.8 1 deposition event size (mg/m2 n resp. mg/m2s) c u m u la tiv e d is tr ib u tio n f u n ct io n no3 no3 nss−so4 nss−so4 nh4 nh4 − number 2− number + number − mass 2− mass + mass fig. 4 cumulative distribution function of number and mass distributions of no�3 -, nss-so 2� 4 and nh � 4 -deposition. 0 5 10 15 20 60 100 (a) 0 0.1 0.2 0.3 0.4 0.5 (b) 0 0.1 0.2 0.3 0.4 0.5 (c) c o n ce n tr a tio n , m g /l n r e sp . m g /l s 0 0.1 0.2 0.3 0.4 0.5 (d) 11 /2 00 9 12 /2 00 9 01 /2 01 0 02 /2 01 0 03 /2 01 0 04 /2 01 0 05 /2 01 0 06 /2 01 0 07 /2 01 0 08 /2 01 0 09 /2 01 0 10 /2 01 0 11 /2 01 0 12 /2 01 0 01 /2 01 1 02 /2 01 1 03 /2 01 1 04 /2 01 1 05 /2 01 1 m m fig. 5 (a) precipitation amount. black bars indicate precipitation events with non-isolated concentration observations. red bars indicate precipitation events with isolated concentration samples. event average concentrations of (b) no�3 ; (c) nss-so 2� 4 and (d) nh � 4 during the sampling campaign. red markers indicate isolated and complete events. reactive nitrogen and sulphate wet deposition, svalbard r. kühnel et al. 8 (page number not for citation purpose) citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 autumn, winter and early spring and lasted over several days. the event average concentrations of no � 3 and nh � 4 show values mainly under 0.1 mg l �1 n (fig. 5). some high concentrations in the range of 0.1�0.2 mg l�1 n occurred during april�june 2010, october�november 2010 and april 2012. two events with extremely high concentrations occurred during april 2010 and april 2011 with values in the range of 0.2�0.5 mg l�1 n. concentrations of nh � 4 were lower than the no � 3 concentrations in general, and the nss-so 2� 4 concentrations are mostly to be found below 0.2 mg l �1 s (fig. 5). the events with higher nss-so 2� 4 concentrations seem to be the same as the ones with high no � 3 and nh � 4 concentrations, and mostly occurred during spring. in general, the nss-so 2� 4 concentrations show higher absolute values but considering that the ratio of molecular weight of sulphur to nitrogen is 3:1, the molar concentrations seem to be similar. the majority of no � 3 and nh � 4 deposition events were below 0.1 mg m �2 n, as apparent from the cumulative distribution function (fig. 3), although strong events in the range of 0.1� 1 mg m�2 n were observed throughout the whole sampling campaign (fig. 6). five no � 3 deposition events with even higher values were observed in november 2009, may 2010, october 2010, the end of april and the beginning of may 2011. the highest event in november 2009 reached values close to 6 mg m �2 n. even though the strongest deposition events of nh � 4 seem to be the same as for no � 3 ; the values were in general lower; except for the two strong events at the end of april 2011 and beginning of may 2011. the majority of nss-so 2� 4 deposition events were below 0.4 mg m �2 s (fig. 5). as for nh � 4 and no � 3 ; strong events in the range between 0.4 and 1 mg m �2 s were observed throughout the sampling campaign. the strongest events coincided with those of nh � 4 and no � 3 and show values between 2 and 5 mg m �2 . using the same definitions of the solid (16 september� 2 june) and liquid (3 june�15 september) precipitation season as in kühnel et al. (2011), the total depositions during the 2009 solid season were 12 mg m �2 n for no � 3 ; 16 mg m �2 s for nss-so 2� 4 and 3 mg m �2 n through nh � 4 : total depositions during the solid season of 2010 were 10 mg m �2 n for no � 3 ; 18 mg m �2 s for nss-so 2� 4 and 12 mg m �2 n for nh � 4 : during the liquid precipitation season of 2010, the deposition was 0.7 mg m �2 for no3 � , 0.8 mg m �2 s for nss-so 2� 4 and 0.3 mg m �2 n for nh � 4 : a scatter plot of event average concentration versus precipitation amount is shown in fig. 7. the plot shows a large variety of observed concentration�precipitation 0 0.1 0.2 0.3 0.4 0.5 2 4 6 0 0.1 0.2 0.3 0.4 0.5 2 4 d e p o si tio n , m g /m 2 n r e sp . m g /m 2 s 0 0.1 0.2 0.3 0.4 0.5 2 4 11 /2 00 9 12 /2 00 9 01 /2 01 0 02 /2 01 0 03 /2 01 0 04 /2 01 0 05 /2 01 0 06 /2 01 0 07 /2 01 0 08 /2 01 0 09 /2 01 0 10 /2 01 0 11 /2 01 0 12 /2 01 0 01 /2 01 1 02 /2 01 1 03 /2 01 1 04 /2 01 1 05 /2 01 1 (a) (b) (c) fig. 6 deposition events of (a) no�3 ; (b) nss-so 2� 4 and (c) nh � 4 during the sampling campaign. red bars indicate isolated and complete events. r. kühnel et al. reactive nitrogen and sulphate wet deposition, svalbard citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 combinations for all three chemical components. no significant linear relationship between event average concentration and precipitation amount could be found and r 2 values are close to zero for the analysis of both all events and the analysis of only isolated and complete events. the mean event average concentration of the events in group a was 0.05 mg l �1 n for no � 3 ; 0.11 mg m �2 s for nss-so 2� 4 and 0.04 mg m �2 n for nh � 4 : the mean event averages of group b were 0.05 mg m �2 n for no � 3 ; 0.10 mg m �2 s for nss-so 2� 4 and 0.05 mg m �2 n for nh � 4 : the total deposition of the different scenarios and the control run, as well as the increase of the total deposition compared to the control run as a percentage, are given in table 2. scenario i gave the biggest increase with 20%, as expected. scenario ii gave an increase of only 3�4%, while scenario ii gave an increase of 16�17%. discussion precipitation sampling, especially in the harsh and windy environment of zeppelin station is a difficult task. a comparison of true and measured precipitation showed that the true precipitation might be 50% higher than the observed value (hansen-bauer et al. 1996). the differences are normally greater for solid deposition than for liquid precipitation. therefore, the deposition magnitudes presented in this paper might be underestimated. another problem while sampling solid precipitation is drifting snow. under strong wind conditions, snow from the ground might be transported into the sampler, where it mixes with freshly fallen snow affecting the chemical signature of the precipitation as well as precipitation amount. it is important to keep these effects in mind when interpreting the results presented here. the calculation of deposition values was further complicated by the different sampling intervals of the concentration and precipitation measurements. while the precipitation samplers at zeppelin station have the advantage of being remote from local contamination at ny-ålesund, the distance between zeppelin station and the precipitation measurement site in ny-ålesund introduces uncertainties into the deposition calculations. in addition to differing precipitation amounts caused by dissimilar catch efficiencies of the samplers as well as by influences of drift snow, the observed precipitation amount might differ through precipitation generated below zeppelin station, riming effects at either site, and evaporation or condensation below zeppelin station. precipitation generation in the lowest 500 m is unlikely. 0.1 1 10 100 0.001 0.01 0.1 1 precipitation amount (mm) a vg . c o n ce n tr a tio n ( m g /l n r e sp . m g /l s ) 1 mg/m 2 0.1 mg/m 20.01 mg/m 2 0.001 mg/m 2 no3 nss−so4 nh4 − 2− + fig. 7 scatter plot of precipitation amount versus event average concentrations. filled markers indicate data from isolated and complete events. diagonal lines show event deposition of no�3 ; nh � 4 and nss-so 2� 4 in mg m �2 n resp. mg m �2 s. table 2 total deposition of scenarios and increase compared to control in percent. control scenario i scenario ii scenario iii no � 3 mg/m 2 n 36 43 (�20%) 37 (�3%) 42 (�17%) nss-so2�4 mg/m 2 s 69 83 (�20%) 72 (�4%) 80 (�16%) nh � 4 mg/m 2 n 32 37 (�20%) 33 (�3%) 37 (�17%) precipitation (mm) 667 801 (�20%) 691 (�4%) 777 (�16%) reactive nitrogen and sulphate wet deposition, svalbard r. kühnel et al. 10 (page number not for citation purpose) citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 precipitating clouds are expected to be vertically thicker with precipitation forming in the upper parts of a cloud. loss through evaporation in the lowest 500 m is expected to happen only during weak precipitation events whilst an increase in precipitation particles in this altitude range would need a surplus of moisture and enough time for the condensation process itself to make a significant difference. a possible addition of precipitation by riming of fog inside the samplers might occur at both sites. however, this would be limited to a few events per season. the gain from such events is not expected to be comparable to medium or strong deposition events. the techniques employed in this study assume that the chemical signature of the precipitation at zeppelin station is similar to that in ny-ålesund. deviations from this assumption might arise if the precipitation at the two observation locations is coming from different air masses or if additional atmospheric nitrogen is washed out below zeppelin station. although the spatial separation of the sampling locations is small enough to assume that they receive precipitation from the same air masses, additional wash-out of atmospheric nitrogen pollution below zeppelin station cannot be ruled out. simultaneous sampling campaigns at zeppelin station and ny-ålesund would be needed to quantify the effect of additional wash-out. comparing the average concentrations from zeppelin station in 2010 with the average concentrations in europe during 2009, one can see that the concentrations from zeppelin station are one order of magnitude smaller in the case of no � 3 and nh � 4 : the average values in europe for no � 3 and nh � 4 were in the range of 0.2�0.7 mg l �1 n (hjellbrekke & fjæraa 2011). the highest concentrations were observed in central europe while coastal regions showed comparatively low concentrations. the nss-so 2� 4 concentrations on the european mainland ranged from 0.1 to 1.0 mg l �1 (hjellbrekke & fjæraa 2011) with lower values in the coastal areas. the observed average from zeppelin station is comparable to low values found in ireland, scotland and norway (hjellbrekke & fjæraa 2011). the cumulative distribution functions presented in this study corroborate the findings of kühnel et al. (2011) in their analysis of weekly precipitation observations that about half of the mass of no � 3 ; nh � 4 and nss-so 2� 4 by wet deposition is deposited by the strongest 5 to 10% of deposition events. these events can be identified from the overview plots (figs. 5 and 6) and the scatter plot (fig. 7) as longer lasting, strong precipitation events with elevated concentrations. there are several events with either high concentrations but low precipitation or vice versa. however, it is the combination of both high concentrations and high precipitation amount that is responsible for strong deposition events controlling the budget. the strongest events*with deposition greater 1 mg m �2 n or 1 mg m �2 s*occur during november 2009, may 2010 and april/may 2011. these are the months when precipitation events are stronger in general, the ground is covered by snow and soil productivity is limited. the deposited nitrogen is stored in the snowpack and might be re-emitted to a limited extent into the atmosphere (beine et al. 2003). the remaining nitrogen will be flushed from the snowpack during snowmelt in spring and become available to soil ecosystems when productivity picks up. although deposition took place throughout the whole sampling campaign, no strong events were observed in the time period when the tundra soils were snow-free and productive. deposition during the sampling campaign was less than the average deposition presented by kühnel et al. (2011). this was especially marked for nss-so 2� 4 and nh � 4 ; which had distinctly lower deposition during both the solid and liquid seasons. no � 3 showed distinctly lower values compared to the average during the liquid season 2010. however, the observed deposition during the solid season was still in the range of observed deposition presented by kühnel et al. (2011), which is not the case for the liquid season. part of this difference was caused by the incomplete reconstruction of deposition events and the fact that the solid seasons were not completely covered by the sampling campaign. the rest of the difference might be caused by the difference in sampling location. while kühnel et al. (2011) calculated averages from observations in ny-ålesund, close to sea level, the observations of the campaign reported here were collected at zeppelin mountain. this might especially influence the nh � 4 and so 2� 4 budgets. for example, nh � 4 deposition might be augmented in ny-ålesund due to emissions from guano produced by local bird colonies, or by nh � 4 emission from the nearby ocean. sea-salt sulphur causes an uncertainty of the nss-so 2� 4 estimates since the correction ratios are not always ideal. hence, the difference in elevation and proximity to the ocean, and therefore different loadings of sea-salt sulphur, could introduce differences between the two sets of observations. precipitation over the arctic is predicted to increase by 20% during the 21st century (cassano et al. 2007). synoptic patterns are expected to change such that occurrences of situations with strong icelandic lows increase (cassano et al. 2007). the increase in winter precipitation is expected to be highest over the north atlantic storm tracks and regions of extreme precipitation are expected to extend further north (saha et al. 2006). r. kühnel et al. reactive nitrogen and sulphate wet deposition, svalbard citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 based on the observations presented here and an as yet unpublished trajectory study by kühnel (unpubl. ms.), this increase is expected to augment nitrogen and sulphur deposition on svalbard. however, the magnitude of this increase is hard to quantify. no significant association between precipitation amount and no � 3 -, nssso 2� 4 and nh � 4 concentrations could be found. the differences between the mean event average concentrations of groups a and b were very small. increasing the precipitation by 20% resulted in 20% more deposition, as expected (scenario i). increasing only low precipitation events by 20% (scenario ii) resulted in a slight deposition increase of 3�4%, while increasing the strong precipitation events by 20% resulted in an increase in deposition of 16�17%. as is apparent from table 1, this pattern is caused by the gain in precipitation amount itself: the concentrations of the events play a minor role. the amount of deposition in each group depends, of course, on the chosen divide between groups a and b. lowering the threshold tends to lower the deposition rise in scenario ii and augments the deposition rise in scenario iii. the opposite is true for raising the threshold. the basic finding that the deposition increase is caused mainly by the increase in precipitation, however, remains. nevertheless, it is important to keep in mind that changes in the quantity of arctic precipitation might lead to changes in the distribution of concentrations of sulphur and nitrogen. assuming the pollution burden to stay the same, concentrations would decrease with increasing precipitation. in addition, if precipitation increases for air parcels en route to the arctic, the scavenging on the way will also be greater, which removes parts of the nitrogen burden before it reaches the arctic. a similar effect was observed in a model study of future nitrogen deposition in north-western europe (hole & engardt 2008). those scavenging effects are, however, not included in the scenarios presented in this study. changes in transport patterns and the chemical signature of precipitation need to be included in any well-grounded estimate of future changes in nitrogen and sulphur deposition, an analysis which is beyond the scope of this paper. summary and conclusion precipitation sampling for chemical analysis was conducted from november 2009 until may 2011 at zeppelin station, svalbard, with a close to daily sampling rate. during the campaign, 125 precipitation events were registered. the collected samples were analysed for no � 3 ; nh � 4 and nss-so 2� 4 by ion chromatography. deposition of the same chemical species was calculated by utilizing precipitation observations from the norwegian meteorological institute in ny-ålesund. the bulk of no � 3 and nh � 4 deposition events were in the range of 0.01�0.1 mg m�2 n while the bulk of nssso 2� 4 deposition events were in the range of 0.02�0.3 mg m �3 s. the observations made during the campaign supported the findings of kühnel et al. (2011) that half of the deposited nitrogen and sulphur mass is caused by the strongest 10% of deposition events. these have been identified as longer lasting events with raised concentrations of nitrogen and sulphur and higher quantities of precipitation. the calculated budgets in this study showed lower values compared to the ones by kühnel et al. (2011), which may be partly explained by gaps during the sampling campaign and the difference in altitude of the sampling location. the observations of this study did not allow for a thorough projection of future nitrogen and sulphur deposition on svalbard, given the expected 20% increase in precipitation over the arctic (cassano et al. 2007). the scenarios studied in this paper indicated that deposition is closely connected to precipitation amount, and increasing precipitation can be expected to lead to increasing deposition, assuming constant emissions of reactive nitrogen and sulphur on the european continent. for further projections, future changes in the nitrogen and sulphur concentration in precipitation and the transport of pollution into the arctic need to be undertaken. changes in the occurrence of blocking situations over the european continent require special attention as they are responsible for surges of polluted air masses to the arctic, leading to strong deposition (iversen & joranger 1985). acknowledgements we would like to thank the norwegian meteorological institute for providing precipitation data. we would also like to thank the staff at the norwegian polar institute’s sverdrup station for their help in maintaining the samplers. without their help, this study would not have been possible. this study was a part of the collaborative, interdisciplinary project sources, sinks and impacts of atmospheric nitrogen deposition in the arctic. we would like to thank the marie curie fellowship (marie curie initial training network nsink itn2007.1.1, env. 215503) for funding this project. this is a contribution to the top-level research initiative, cryosphere�atmosphere interactions in a changing arctic climate. reactive nitrogen and sulphate wet deposition, svalbard r. kühnel et al. 12 (page number not for citation purpose) citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 references aas w., solberg s., manø s. & yttri k.e. 2011. overvåking av langtransportert forurenset luft og nedbør. (monitoring of longrange transported air pollutants.) report 1099/2011. (summary in english.) oslo: climate and pollution agency. arens s.j.t., sullivan p.f. & welker j.m. 2008. nonlinear responses to nitrogen and strong interactions with nitrogen and phosphorus additions drastically alter the structure and function of a high arctic ecosystem. journal of geophysical research*biogeosciences 113, g03s09, doi: 10.1029/ 2007jg000508. barrie l.a. 1986. arctic air pollution: an overview of current knowledge. atmospheric environment 20, 643�663. beine h.j., domine f., ianniello a., nardino m., allegrini i., teinila k. & hillamo r. 2003. fluxes of nitrates between snow surfaces and the atmosphere in the european high arctic. atmospheric chemistry and physics 3, 335�346. beine h.j., engardt m., jaffe d.a., hov o., holmen k. & stordal f. 1996. measurements of nox and aerosol particles at the ny-alesund zeppelin mountain station on svalbard: influence of regional and local pollution sources. atmospheric environment 30, 1067�1079. bergin m.h., jaffrezo j.l., davidson c.i., dibb j.e., pandis s.n., hillamo r., maenhaut w., kuhns h.d. & makela t. 1995. the contributions of snow, fog, and dry deposition to the summer flux of anions and cations at summit, greenland. journal of geophysical research*atmospheres 100, 16275�16288. cassano j.j., uotila p. & lynch a. 2006. changes in synoptic weather patterns in the polar regions in the twentieth and twenty-first centuries, part 1: arctic. international journal of climatology 26, 1027�1049. cassano j.j., uotila p., lynch a.h. & cassano e.n. 2007. predicted changes in synoptic forcing of net precipitation in large arctic river basins during the 21st century. journal of geophysical research*biogeosciences 112, g04s49, doi: 10. 1029/2006jg000332. cheng m.d., hopke p.k., barrie l., rippe a., olson m. & landsberger s. 1993. qualitative determination of source regions of aerosol in canadian high arctic. environmental science & technology 27, 2063�2071. dickerson r.r. 1985. reactive nitrogen compounds in the arctic. journal of geophysical research*atmospheres 90, 10739�10743. eneroth k., kjellström e. & holmén k. 2003. a trajectory climatology for svalbard; investigating how atmospheric flow patterns influence observed tracer concentrations. physics and chemistry of the earth parts a/b/c 28, 1191�1203. erisman j.w., grennfelt p. & sutton m. 2003. the european perspective on nitrogen emission and deposition. environment international 29, 311�325. fagerli h. & aas w. 2008. trends of nitrogen in air and precipitation: model results and observations at emep sites in europe, 1980�2003. environmental pollution 154, 448�461. førland e.j., hanssen-bauer i. & nordli p.ø. 1997. climate statistics and longterm series of temperature and precipitation at svalbard and jan mayen. dnmi klima report 21/97. oslo: norwegian meteorological institute. galloway j.n., dentener f.j., capone d.g., boyer e.w., howarth r.w., seitzinger s.p., asner g.p., cleveland c.c., green p.a., holland e.a., karl d.m., michaels a.f., porter j.h., townsend a.r. & vorosmarty c.j. 2004. nitrogen cycles: past, present, and future. biogeochemistry 70, 153�226. galloway j.n., schlesinger w.h., levy h., michaels a. & schnoor j.l. 1995. nitrogen-fixation*anthropogenic enhancement*environmental response. global biogeochemical cycles 9, 235�252. gordon c., wynn j.m. & woodin s.j. 2001. impacts of increased nitrogen supply on high arctic heath: the importance of bryophytes and phosphorus availability. new phytologist 149, 461�471. grannas a.m., jones a.e., dibb j., ammann m., anastasio c., beine h.j., bergin m., bottenheim j., boxe c.s., carver g., chen g., crawford j.h., domine f., frey m.m., guzman m.i., heard d.e., helmig d., hoffmann m.r., honrath r.e., huey l.g., hutterli m., jacobi h.w., klan p., lefer b., mcconnell j., plane j., sander r., savarino j., shepson p.b., simpson w.r., sodeau j.r., von glasow r., weller r., wolff e.w. & zhu t. 2007. an overview of snow photochemistry: evidence, mechanisms and impacts. atmospheric chemistry and physics 7, 4329�4373. grice s., stedman j., kent a., hobson m., norris j., abbott j. & cooke s. 2009. recent trends and projections of primary no2 emissions in europe. atmospheric environment 43, 2154�2167. hansen-bauer i., førland e.j. & nordli p.ø. 1996. measured and true precipitation at svalbard. dnmi klima report 31/96. oslo: norwegian meteorological institute. hastings m.g., jarvis j.c. & steig e.j. 2009. anthropogenic impacts on nitrogen isotopes of ice-core nitrate. science 324, 1288�1288. hjellbrekke a.g. & fjæraa a.m. 2011. data report 2009* acidifying and eutrophying compounds and particulate matter. emep/ccc report 1/2011. kjeller: norwegian institute for air research. hodson a., anesio a.m., tranter m., fountain a., osborn m., priscu j., laybourn-parry j. & sattler b. 2008. glacial ecosystems. ecological monographs 78, 41�67. hodson a.j., mumford p.n., kohler j. & wynn p.m. 2005. the high arctic glacial ecosystem: new insights from nutrient budgets. biogeochemistry 72, 233�256. hole l. & engardt m. 2008. climate change impact on atmospheric nitrogen deposition in northwestern europe: a model study. ambio 37, 9�17. hole l.r., christensen j.h., ruoho-airola t., torseth k., ginzburg v. & glowacki p. 2009. past and future trends in concentrations of sulphur and nitrogen compounds in the arctic. atmospheric environment 43, 928�939. isaksson e., hermanson m., sheila h.c., igarashi m., kamiyama k., moore j., motoyama h., muir d., pohjola r. kühnel et al. reactive nitrogen and sulphate wet deposition, svalbard citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 13 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 v., vaikmae r., van de wal r.s.w. & watanabe o. 2003. ice cores from svalbard*useful archives of past climate and pollution history. physics and chemistry of the earth 28, 1217�1228. iversen t. 1984. on the atmospheric transport of pollution to the arctic. geophysical research letters 11, 457�460. iversen t. & joranger e. 1985. arctic air-pollution and largescale atmospheric flows. atmospheric environment 19, 2099� 2108. kang s., qin d., mayewski p. & gjessing y. 2001. snow chemistry in svalbard, arctic. bulletin of glaciological research 18, 9�13. kärkäs e., teinila k., virkkula a. & aurela m. 2005. spatial variations of surface snow chemistry during two austral summers in western dronning maud land, antarctica. atmospheric environment 39, 1405�1416. klonecki a., hess p., emmons l., smith l., orlando j. & blake d. 2003. seasonal changes in the transport of pollutants into the arctic troposphere-model study. journal of geophysical research*atmospheres 108, article no. 8367, doi: 10.1029/ 2002jd002199. krawczyk w.e., bartoszewski s.a. & siwek k. 2008. rain water chemistry at calypsobyen, svalbard. polish polar research 29, 149�162. krupa s.v. 2002. sampling and physico-chemical analysis of precipitation: a review. environmental pollution 120, 565�594. kühnel r., roberts t.j., björkman m.p., isaksson e., aas w., holmén k. & ström j. 2011. 20-year climatology of no3and nh4� wet deposition at ny-ålesund, svalbard. advances in meteorology 2011, article no. 406508, doi: 10. 10.1155/2011/406508. millero f.j., feistel r., wright d.g. & mcdougall t.j. 2008. the composition of standard seawater and the definition of the reference-composition salinity scale. deep-sea research part i 55, 50�72. monks p.s., granier c., fuzzi s., stohl a., williams m.l., akimoto h., amann m., baklanov a., baltensperger u., bey i., blake n., blake r.s., carslaw k., cooper o.r., dentener f., fowler d., fragkou e., frost g.j., generoso s., ginoux p., grewe v., guenther a., hansson h.c., henne s., hjorth j., hofzumahaus a., huntrieser h., isaksen i.s.a., jenkin m.e., kaiser j., kanakidou m., klimont z., kulmala m., laj p., lawrence m.g., lee j.d., liousse c., maione m., mcfiggans g., metzger a., mieville a., moussiopoulos n., orlando j.j., o’dowd c.d., palmer p.i., parrish d.d., petzold a., platt u., poschl u., prevot a.s.h., reeves c.e., reimann s., rudich y., sellegri k., steinbrecher r., simpson d., ten brink h., theloke j., van der werf g.r., vautard r., vestreng v., vlachokostas c. & von glasow r. 2009. atmospheric composition change*global and regional air quality. atmospheric environment 43, 5268�5350. ottar b., pacyna j.m. & berg t.c. 1986. aircraft measurements of air pollution in the norwegian arctic. atmospheric environment 20, 87�100. peters g.p., nilssen t.b., lindholt l., eide m.s., glomsrød s., eide l.i. & fuglestvedt j.s. 2011. future emissions from shipping and petroleum activities in the arctic. atmospheric chemistry and physics 11, 5305�5320. quinn p.k., miller t.l., bates t.s., ogren j.a., andrews e. & shaw g.e. 2002. a 3-year record of simultaneously measured aerosol chemical and optical properties at barrow, alaska. journal of geophysical research*atmospheres 107, article no. 4130, doi: 10.1029/2001jd001248. quinn p.k., shaw g., andrews e., dutton e.g., ruoho-airola t. & gong s.l. 2007. arctic haze: current trends and knowledge gaps. tellus series b 59, 99�114. raatz w.e. 1984. observations of arctic haze during the ptarmigan weather reconnaissance flights, 1948�1961. tellus series b 36, 126�136. raatz w.e. & shaw g.e. 1984. long-range tropospheric transport of pollution aerosols into the alaskan arctic. journal of climate and applied meteorology 23, 1052�1064. rahn k.a. 1981. relative importance of north america and eurasia as sources of arctic aerosol. atmospheric environment 15, 1447�1455. rahn k.a. 1985. progress in arctic air chemistry, 1980�1984. atmospheric environment 19, 1987�1994. roberts t.j., hodson a.j., evans c.d. & holmén k. 2010. modelling the impacts of a nitrogen pollution event on the biogeochemistry of an arctic glacier. annals of glaciology 51, 163�170. saha s.k., rinke a. & dethloff k. 2006. future winter extreme temperature and precipitation events in the arctic. geophysical research letters 33, l15818, doi: 10.1029/ 2006gl026451. samyn d., vega c. & pohjola v.a. 2012. nitrate and sulfate anthropogenic trends in the 20th century from five svalbard ice cores. arctic, antarctic, and alpine research 44, 490�499. seinfeld j.h. & pandis s.n. 2006. atmospheric chemistry and physics*from air pollution to climate change. 2nd edn. new york: john wiley. shaver g.r. & chapin f.s. 1980. response to fertilization by various plant-growth forms in an alaskan tundra*nutrient accumulation and growth. ecology 61, 662�675. shaw g.e. 1995. the arctic haze phenomenon. bulletin of the american meteorological society 76, 2403�2413. stohl a. 2006. characteristics of atmospheric transport into the arctic troposphere. journal of geophysical research* atmospheres 111, d11306, doi: 10.1029/2005jd006888. sutton m.a., howard c.m., erisman j.w., billen g., bleeker a., grennfelt p., van grinsven h. & grizzeti b. (eds.) 2011. the european nitrogen assessment. sources, effects and policy perspectives. cambridge: cambridge university press. toom-sauntry d. & barrie l.a. 2002. chemical composition of snowfall in the high arctic: 1990�1994. atmospheric environment 36, 2683�2693. yang d.q. 1999. an improved precipitation climatology for the arctic ocean. geophysical research letters 26, 1625�1628. reactive nitrogen and sulphate wet deposition, svalbard r. kühnel et al. 14 (page number not for citation purpose) citation: polar research 2013, 32, 19136, http://dx.doi.org/10.3402/polar.v32i0.19136 http://www.polarresearch.net/index.php/polar/article/view/19136 http://dx.doi.org/10.3402/polar.v32i0.19136 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <feff00560065007200770065006e00640065006e0020005300690065002000640069006500730065002000450069006e007300740065006c006c0075006e00670065006e002c00200075006d002000650069006e0065006e00200042006500720069006300680074002000fc00620065007200200064006900650020005000440046002f0058002d0033002d004b006f006d007000610074006900620069006c0069007400e4007400200065007200680061006c00740065006e00200075006e00640020005000440046002d0044006f006b0075006d0065006e007400650020006e00750072002000640061006e006e0020007a0075002000650072007300740065006c006c0065006e002c002000770065006e006e0020007300690065002000fc0062006500720020006400690065007300650020004b006f006d007000610074006900620069006c0069007400e400740020007600650072006600fc00670065006e002e0020005000440046002f00580020006900730074002000650069006e0065002000490053004f002d004e006f0072006d0020007a0075006d002000410075007300740061007500730063006800200076006f006e0020006400690067006900740061006c0065006e00200044007200750063006b0076006f0072006c006100670065006e002e0020005700650069007400650072006500200049006e0066006f0072006d006100740069006f006e0065006e0020007a0075006d002000450072007300740065006c006c0065006e00200076006f006e0020005000440046002f0058002d0033002d006b006f006d00700061007400690062006c0065006e0020005000440046002d0044006f006b0075006d0065006e00740065006e002000660069006e00640065006e002000530069006500200069006d0020004100630072006f006200610074002d00480061006e00640062007500630068002e00200044006900650020005000440046002d0044006f006b0075006d0065006e007400650020006b00f6006e006e0065006e0020006d006900740020004100630072006f0062006100740020006f0064006500720020006d00690074002000640065006d002000520065006100640065007200200034002e003000200075006e00640020006800f600680065007200200067006500f600660066006e00650074002000770065007200640065006e002e> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu (settings for the rampage workflow.) >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice no job name cloning and heterologous expression of two cold-active lipases from the antarctic bacterium psychrobacter sp. gpor_189 421..429 lin xuezheng,1 cui shuoshuo,1 xu guoying,2 wang shuai,1 du ning1 & shen jihong1 1 key laboratory of marine bioactive substances, first institute of oceanography, soa, 6 xianxialing road, qingdao 266061, china 2 ocean college, shandong university at weihai, 180 wenhuaxi road, weihai shandong 264209, china abstract antarctic bacteria producing extracellular lipolytic enzymes with activity at low temperature were isolated, and the most promising strain, named g, was identified as a psychrobacter species based on 16s rdna sequence alignment. the genomic dna of this bacterium was used to construct its plasmid genomic library into puc118 plasmid vectors, and to screen the cold-active lipolytic enzyme genes. two genes encoding for cold-active lipolytic enzymes, lip-1452 (with an open reading frame of 1452 bp in length) and lip-948 (with an open reading frame of 948 bp in length), were screened. the primary structure of the two lipases deduced from the nucleotide sequence showed a consensus pentapeptide containing the active serine (lip-1452, gdsag, and lip-948, gnsmg) and a conserved his-gly dipeptide in the n-terminal part of the enzyme. protein sequence alignment and conserved regions analysis indicated that the two lipases probably belonged to family iv and family v of the bacterial lipolytic enzymes, respectively. the upstream and downstream sequences of the two lipolytic lipases were also obtained. the two lipase genes were cloned into the expression vector pcold iii and integrated into escherichia coli bl21 (de3). the functional expression of both lipase genes by e. coli bl21 (de3) cells was observed as the formation of clear haloes around colonies on a 1% (vol/vol) tributyrin plate upon induction with isopropyl-b-dthiogalactopyranoside at 5°c. a lipase activity assay showed that the specific activity of the pcold iii+lip-948 expression system was up to 3.7 u ml-1, whereas that of pcold iii+lip-1452 was very low. keywords antarctic; cold-active lipase; gene cloning; gene expression; psychrobacter. correspondence lin xuezheng, key laboratory of marine bioactive substances, first institute of oceanography, soa, 6 xianxialing road, qingdao 266061, china. e-mail: linxz@fio.org.cn doi:10.1111/j.1751-8369.2010.00189.x enzymes from psychrotrophic and psychrophilic microorganisms have received increasing attention because of their relevance for both basic and applied research. research efforts have been stimulated by the recognition that cold-adapted enzymes might offer novel opportunities for biotechnological exploitation, based on their high catalytic activity at low temperatures, low thermostability and unusual specificities. cold-active enzymes with huge biotechnological potentials include protease, lipase, amylase and cellulase in the detergent industry, b-galactosidase in the dairy industry, dehydrogenase as a biosensor in environmental protection, oxidase in bioremediation, and many enzymes, e.g., methylase and aminotransferase, in biotransformation (alquati et al. 2002; cieśliński et al. 2005; parra et al. 2008). bacteria produce different classes of lipolytic enzymes, including carboxylesterases (ec 3.1.1.1) that hydrolyse water-soluble esters and lipases (ec 3.1.1.3) that hydrolyse long-chain triacylglycerol substances, catalysing both the hydrolysis and the synthesis of acylglycerides and other fatty acid esters (rosenau et al. 2000; lee et al. 2004). lipolytic enzymes are important biocatalysts for various industrial applications (e.g., ester synthesis, optical resolution, transesterification and washing) because, among other characteristics, they lack requirements for cofactors, they are remarkably stable in organic solvents, they have broad substrate specificity, and they have regionand stereo-selectivity. in the past decade, increasing attention has been drawn to potential applications of cold-adapted lipolytic enzymes from microorganisms populating permanently cold environments (pfeffer et al. 2007; długołecka et al. 2008). these enzymes are characterized by higher kcat and physiological polar research 29 2010 421–429 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 421 mailto:linxz@fio.org.cn efficiency (kcat/km), and by a lower and rather constant km at temperatures close to 0°c (yang et al. 2008). several recent papers reviewed cold-active microbial lipases (joseph et al. 2007; joseph et al. 2008). a dozen genes encoding cold-active lipolytic enzymes have been cloned from different species and environmental metagenomes (choo et al. 1998; quyen et al. 1999; alquati et al. 2002; ryu et al. 2006; zhang et al. 2007; długołecka et al. 2008; parra et al. 2008; yang et al. 2008; jeon et al. 2009). from water samples collected off king george island, antarctica, we isolated dozens of cold-adapted microorganisms that can degrade lipids at low temperature (5°c). one of the promising lipolytic strains, named “g”, was identified as a psychrobacter species by molecular identification based on 16s rdna. in this study, we report the cloning and sequencing of two lipase genes from the strain psychrobacter sp. g., and their heterologous expression in escherichia coli bl21 (de3). material and methods samples and isolation of lipolytic enzyme-producing strains surface (0–20 cm) water samples were collected at 62°12′39″s, 58°54′41″w, on 9 january 2008 in the waters off south-western king george island, one of the south shetland islands, using a water sampler (model wb-pm, beijing purity instrument co., beijing, china). the temperature and salinity of the samples were 1.9–2.5°c and 33.1–33.8, respectively. the screening medium comprised 5 g of peptone, 1 g of yeast extract, 10 ml of tributyrin and 1000 ml of seawater. the strains producing lipolytic enzymes were detected by the formation of clear haloes around the colony at 5°c. the lipolytic enzyme activity assay was performed with a substrate of olive oil at 35°c, as described by yang et al. (2004). strains and vectors of the lypolytic strains detetcted, one (g) was selected for further analysis on account of its higher extracellular lipase activity at low temperature, and its low enzymatic optimum temperature. the strain was identified as psychrobacter sp. by molecular identification based on 16s rdna alignment, as described by yang et al. (2004). escherichia coli dh5a and bl21 (de3) were used as host strains for dna manipulation and gene expression, respectively. plasmid vectors puc118 hincii/bap (code d3322; takara biotechnology co., otsu, japan) and pcold iii (code 3363; takara biotechnology) were used as vectors for gene cloning and heterologous expression, respectively. cloning of the lipolytic enzyme genes the chromosomal dna from psychrobacter sp. g was isolated using a genomic dna prep kit (model number dp302-02; tiangen biotech, beijing, china), following the instructions in the manufacturer’s manual. the chromosomal dna was partially digested with sau3ai and 2–6-kb fragments were purified from a 0.8% agarose gel using an agarose gel dna purification kit v2.0 (model number dp209-02; tiangen biotech, beijing, china). these dna fragments were ligated into puc118 hincii/ bap with a dna ligation kit v2.0 (model number d6022; takara biotechnology co.). the resultant plasmids were introduced into e. coli dh5a, providing a genomic library containing 2.1 ¥ 105 cfu/ml recombinant e. coli clones. the colonies producing cold-active lipolytic enzymes were detected by the formation of clear haloes around the colonies on lysogeny broth (lb) agar plates supplemented with ampicillin (50 mg ml-1), 0.1 mm isopropyl b-dthiogalactopyranoside (iptg) and 1% (vol/vol) tributyrin at low temperature (5°c) (yang et al. 2008). the recombinant plasmids from the lipolytic enzyme positive clone were extracted and sequenced. construction of the expression plasmid of lip-1452 and lip-948 an e. coli expression vector, pcold iii, was used to express the lipolytic enzymes in e. coli. based on the upstream and downstream sequences of the known lipolytic enzyme gene sequences, the specific primers for polymerase chain reaction (pcr) amplification were designed and synthesized as follows: primer f1 5′-ctgtagga gctcatgtctaactcaacagtactat-3′, primer r1 5′-cataaatctagaatcaatc ttacaggtaccaa-3′ for lip-1452, and primer f2 5′-ctgtaggagctcatgc tattaaaacgcc t-3′ and primer r2 5′-cataaa tctagattacgccttaaaacatca-3′ for lip-948 were used to generate a pcr product carrying a saci restriction site at its 5′ end and an xbai restriction site at its 3′ end. lipase gene expression in e. coli escherichia coli bl21 (de3) transformed with the expression plasmid pcold iii+lip-1452 or pcold iii+lip-948 was grown overnight with shaking (200 revolutions per min) in 10 ml lb. expression was performed in lb medium (supplemented with 0.2% glucose) with the cold-shock vectors, in accordance with the manufacturer’s instructions. when od600 was 0.5, the culture solution was refrigerated at 15°c and left to stand at the same temperature for 30 min. after adding iptg to a final cloning and expression of cold-active lipases l. xuezheng et al. polar research 29 2010 421–429 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd422 concentration of 0.5 mmol l-1, cells were cultured at 15°c for 24 h. cells were harvested and ruptured by ultrasonic lysis in 25 mmol l-1 sodium phosphate buffer. the cell debris (insoluble fraction) was removed by centrifugation at 12 000 ¥ g for 20 min, and the supernatant was used for lipolytic enzyme assay and sodium dodecyl sulfate polyacrylamide gel electrophoresis (sds-page) analysis. lipolytic enzyme assay and sds-page analysis the lipolytic enzyme assay was performed with tributyrin as substrate at 35°c, as described by pfeffer et al. (2007). one unit (u) of enzymatic activity was defined as the quantity of enzyme that liberates 1 mmol of fatty acids per minute. sds-page was run essentially as described by sambrook & russel (2001). the samples were dissolved in laemmli’s sample buffer and were heated at 95°c for 5 min and cooled before being applied to a gel. the sds gel was composed of a 5% (weight/vol) stacking gel and a 15% (weight/vol) resolving gel. the samples were subjected to electrophoresis first at 80 v on the stacking gel and then 120 v on the resolving gel. after electrophoresis, the gel was fixed and stained with 0.1% (weight/vol) coomassie brilliant blue r-250. results isolation and identification of psychrotrophic strains with cold-active lipolytic activity from nearly 100 strains, 26 strains producing lipolytic enzymes were detected by the formation of clear haloes around the colonies. strain g was selected as the most promising producer of lipolytic enzymes because it had the highest lipolytic activity (12.8 u ml-1 culture) among the 26 strains above when they were cultured at 5°c for 72 h in zobell 2216e medium (ysi china ltd, beijing, china), supplemented with 1% tween 80 (ici america, bridgewater, nj, usa). the optimal temperature of the lipolytic enzyme was about 35°c. the strain was identified as a psychrobacter species based on 16s rdna alignment. the almost-complete 16s rdna sequence of strain g (fj386502), which consisted of 1406 bp, was analysed using the nucleotide–nucleotide basic algorithm alignment search tool (blastn) program for comparing dna sequences. it was found to be more than 99% identical to hundreds of different species psychrobacter, such as psychrobacter cryohalolentis k5 (ay660685), psychrobacter sp. dvs12b (ay864464) and psychrobacter sp. ice-oil-471 (dq521392). cloning of the lipolytic enzyme genes among approximately 20 000 recombinant colonies from the genomic library of psychrobacter sp. g, 10 lipolytic enzyme positive transformants were identified on the basis of the formation of clear haloes around the colony on a tributyrin plate at 5°c, which indicated that they might encode cold-active lipolytic enzymes. from these 10 colonies, two different lipolytic genes that contained an open reading frame of 1452 bp (lip-1452, gu247898; fig. 1) and 948 bp (lip-948, gu247897; fig. 2) were obtained. they encoded 315 and 483 amino acids, giving calculated molecular weights of about 53 and 34 kda, respectively. sequence analysis the protein–protein basic algorithm alignment search tool (blastp) was used to search for homologies to other amino acid sequences deposited in the national center for biotechnology information database (accessible at http://www.ncbi.nlm.nih.gov). the highest homology (98.9%) of lip-1452 was achieved with the a/b-hydrolase fold-3 from p. cryohalolentis k5 (yp_581719). it was 65.3% identical to the cold-active esterase from pseudomomas sp. st1 (af260707), and 54.5% identical to the lipase from psychrobacter sp. 2–17 (abr12515). the two conserved regions, hgggf and gdsag, were identified in lip-1452 (figs. 1, 3). based on the conserved catalytic triad and overall identity of the amino acid sequences, lip-1452 was identified as a member of the hormone-sensitive lipase (hsl) group, namely family iv of the bacterial lipases (fig. 3). lip-1452 probably had a catalytic triad (ser-his-asp), and contained an oxyanion hole to stabilize the tetrahedral intermediate (parra et al. 2008). based on alignment using megalign 5.0 (dnastar, madison, wi, usa), the two conserved regions, hgggf and gdsag, could be identified in the amino acid sequences of lip-1452. the primary structure of the pentapeptide gdsag started at gly297, and ser299 was probably also a member of the triad. perhaps asp414 and his444 were the second and third members of the triad, respectively. the conserved asp was in a consensus sequence ldxl, and the his constituting the triad was preceded by a pro and followed by a gly. all these characters indicated that lip-1452 was a member of the hsl group of bacterial lipases (arpigny et al. 1999; parra et al. 2008). dozens of homologues of lip-948 were obtained through blastp analysis. the highest homology (97.8%) was the a/b hydrolase fold from p. cryohalolentis k5 (yp_579291). it was 82.5% identical to the triacylglycerol lipase from moraxella sp. (af260707). it was also cloning and expression of cold-active lipasesl. xuezheng et al. polar research 29 2010 421–429 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 423 http://www.ncbi.nlm.nih.gov very similar to the triacylglycerol lipase from psychrobacter sp. 7195 (80.6%, caj76164) and psychrobacter immobilis (79.6%, q92104). the two conserved regions, hgfgg and gnsmg, were identified in lip-948 and are shown in figs. 2 and 4. lip-948 probably belonged to family v, based on sequence alignment, especially for the two conserved regions hgfgg and gnsmg. perhaps ser142, asp264 and his291 composed the catalytic triad (figs. 2, 4). it probably contained a signal peptide (met1-ala27), which indicated that lip-948 might be a secreted protein. lipase expression in e. coli the lip-1452 and lip-948 sequences were separately inserted into the expression vector pcold iii, and recombinant plasmid was constructed. e. coli bl21 (de3) cells were then transformed with the recombinant plasmid and induced with 0.1 mm iptg at 15°c. the formation of clear haloes around both lip-1452 and lip-948 colonies on an lb tributyrin plate indicated that there were functional expression of lipolytic enzymes in the expression system above. the total proteins from the fermentation culture medium were analysed using sds-page (figs. 5, 6). new protein bands with molecular masses of approximately 53 and 34 kda, which were consistent with the molecular mass deduced from the nucleotide sequence, were produced by recombinant e. coli harbouring pcold iii+lip1452 and pcold iii+lip-948, respectively. although lipase activity of the two expression systems was detected on a tributyrin plate, when the specific activity was measured with the method used by pfeffer et al. (2007), the enzyme activity of recombinant e. coli harbouring pcold iii+lip1452 was relatively low, whereas the specific activity of the expression system of pcold iii+lip-948 was 3.7 u ml-1 culture (table 1). fig. 1 nucleotide sequence of lip-1452 from psychrobacter sp. g, and its deduced amino acid sequence below. table 1 summary of enzyme activity of lipase gene expressed in different systems. vector halo formation on lb tributyrin plate specific activity (u ml-1) pcold iii no none detected pcold iii+lip-1452 yes none detected pcold iii+lip-948 yes 3.7 cloning and expression of cold-active lipases l. xuezheng et al. polar research 29 2010 421–429 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd424 discussion our work describes two lipolytic enzyme genes from the plasmid genomic library of psychrobacter sp. g, collected from seawater in antarctica. simple overexpression in e. coli was used to determine the enzymatic activity of subclones generated from an original active puc118 clone. the strain was identified as a psychrobacter species for its close similarity at the 16s rdna level to hundreds of species of the psychrobacter genus. the specific lipolytic activity was 12.8 u ml-1, with a substrate of olive oil emulsion, when it was cultured in zobell 2216e medium supplemented with 1% tween 80. the genomic library of psychrobacter sp. g was constructed in puc118 hincii/bap, and was introduced into e. coli dh5a. among 10 colonies forming clear haloes on a tributyrin agar plate, two lipase genes with different opening reading frames were identified. one open reading frame consisted of 1452 (lip-1452) nucleotides that encoded 483 amino acids with a molecular mass of approximately 53 kda and a pi of 5.4. the other open reading frame consisted of 948 (lip-948) nucleotides that encoded 315 amino acids with molecular weights of 34 kda and a pi of 8.0. arpigny et al. (1999) were the first to classify bacterial lipolytic enzymes into eight families based on differences in amino acid sequences and biological properties. family i, the largest group, was further divided into seven subfamilies (i.1–i.7; angkawidjaja & kanaya 2006). the primary structure of lip-1452 and lip-948 indicated that they were probably members of families iv and v, respectively, of the bacterial lipolytic enzymes. the amino acid sequence alignment of lip-1452 indicated the two conserved regions, hgggf and gdsag, were identified in this sequence. perhaps its catalytic triad consisted of ser238, asp414 and his444 (fig. 3). the primary structure of this protein showed that it was a member of family iv, namely the hsl group (arpigny et al. 1999). evidence points to lip-1452 and lip-948 belonging to a large superfamily called the “a/b hydrolase” superfamily. the members of this superfamily share the “nucleophilic elbow”, which is a characteristic sequence motif, gly-xaa-ser-xaa-gly, for most esterases and lipases. the ser residue in this motif constitutes a “catalytic triad” with asp and his residues that are placed in the specific order serine-aspartic acid-histidine in the polypeptide (suzuki et al. 2003). lip-1452 was characterized by the motif gdsag and lip-948 was characterized by gnsmg. lip-1452 had the catalytic triad in the specific order ser299-asp414-his444, and lip-948 had the catalytic triad ser142-asp264-his291. the activity of the recombinant lipase produced by the expression system was relatively low, consistent with fig. 2 nucleotide sequence of lip-948 from psychrobacter sp. g, and its deduced amino acid sequence below. cloning and expression of cold-active lipasesl. xuezheng et al. polar research 29 2010 421–429 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 425 most previous findings (suzuki et al. 2003; pfeffer et al. 2007; długołecka et al. 2008; parra et al. 2008). most of the lipase expressed in e. coli seemed to exist as an inclusion body. there are reports that lipases are not fully processed by some species of e. coli, and lipases aggregate as a result of their own hydrophobicity (yang et al. 2008). both lip-1452 and lip-948 were expressed in e. coli; however, functional heterologous expression was low, especially for lip-1452. because the heterologous expression of lipase in e. coli cells yielded inclusion bodies with no catalytic activity, renaturation studies had to be executed to obtain a catalytically active form of the enzyme (suzuki et al. 2003). however, the expression in an active form of lipase belonging to subfig. 3 alignment of amino acid sequences of lip-1452 with homologous lipases. yp_581719, a/b-hydrolase fold-3 from psychrobacter cryohalolentis k5; af260707, cold-active esterase from pseudomonas sp. st1; abr12515, lipase from pseudomonas sp. 2–17; p24484, lipase from moraxella sp. cloning and expression of cold-active lipases l. xuezheng et al. polar research 29 2010 421–429 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd426 families i.1 and i.2 depends on a chaperone protein named lipase-specific foldase, the gene of which is located downstream of the lipase gene for the efficient secretion and folding of active lipase (arpigny et al. 1999; quyen et al. 1999), whereas the folding of subfamily i.3 lipases does not require the assistance of any molecular chaperone (angkawidjaja & kanaya 2006). for example, a lipase belonging to subfamily i.1 or i.2 was heterologously expressed in e. coli, and the chemical refolding of inactive lipase in the absence of its chaperone yielded only 25 u mg-1, whereas in a simple and rapid in vitro refolding procedure with its modified and truncated chaperone, functionally active lipase was obtained with a specific activity of up to 4850 u mg-1 and a yield of 31 400 u g-1 of e. coli wet cells (quyen et al. 1999). iizumi et al. (1991) reported that the activator gene (act), existing downstream of the lipase (lip) of pseudomonas fragi, enhanced the heterologous expression of lip in e. coli. when the lip was expressed in e. coli using lac promoter on the puc plasmid vector, the lipase activity of e. coli carrying both the lip and act was 200 times greater than that carrying only lip. acknowledgements this work was financially supported by china’s national high-tech r & d program (2007aa091905) and the basic scientific research operation fund of china (gy022007-t11). fig. 4 alignment of amino acid sequences of lip-948 with homologous lipases. yp_579291, a/b-hydrolase fold from psychrobacter cryohalolentis k5; p24640, triacylglycerol lipase from moraxella sp.; caj76164, triacylglycerol lipase from psychrobacter sp. 7195; q02104, triacylglycerol lipase from psychrobacter immobilis. cloning and expression of cold-active lipasesl. xuezheng et al. polar research 29 2010 421–429 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 427 references alquati c., gioia l.d., santarossa g., alberghina l., fantucci p. & lotti m. 2002. the cold-active lipase of pseudomonas fragi: heterologous expression, biochemical characterization and molecular modeling. european journal of biochemistry 269, 3321–3328. angkawidjaja c. & kanaya s. 2006. family i.3 lipase: bacterial lipase secreted by the type i secretion system. cellular and molecular life sciences 63, 2806–2817. arpigny j.l. & jaeger k.e. 1999. bacterial lipolytic enzymes: classification and properties. biochemistry journal 343, 177–183. choo d.w., kurihara t., suzuki t., soda k. & esaki n. 1998. a cold-adapted lipase on an aladkan psychrotroph, pseudomonas sp. strain b11-1: gene cloning and enzyme purification and characterization. applied environmental microbiology 64, 484–491. cieślinśki h., kur j., białkowska a., baran i., makovski k. & turkiewicz m. 2005. cloning, expression, and purification of a recombinant cold-adapted b-galactosidase from antarctic bacterium pseudoalteromonas sp. 22b. protein expression and purification 59, 27–34. długołecka a., cieśliński h., turkieewicz m., białkowska a.m. & kur j. 2008. extracellular secretion of pseudoalteromonas sp. cold-adapted esterase in escherichia coli in the presence of pseudoalteromonas sp. components of abc transport system. protein expression and purification 62, 179–184. iizumi t., nakamura k., shimada y., sugihara a., tominaga y. & fukase t. 1991. cloning, nucleotide sequencing, and expression in escherichia coli of a lipase and its activator genes from pseudomonas sp. kwi-56. agricultural biology and chemistry 55, 2349–2357. jeon j.h., kim j.t., kim yj., kim h.y., lee h.s., kang s.g., kim s.j. & lee j.h. 2009. cloning and characterization of a new cold-active lipase from a deep-sea sediment metagenome. applied microbiology and biotechnology 81, 865–874. joseph b., ramteke p.w., thomas g. & shrivastava n. 2007. standard review cold-active microbial lipases: a versatile tool for industrial applications. biotechnology and molecular biology review 2, 39–48. joseph b., ramteke p.w., thomas g. 2008. cold-active microbial lipases: some hot issues and recent developments. biotechnology advances 26, 457– 470. lee s.w., won k., lim h.k., kim j.c., choi g.a. & cho k.y. 2004. screening for novel lipolytic enzymes from uncultured soil microorganisms. applied microbiology and biotechnology 65, 720–726. parra l.p., reyes f., acevedo j.p., salazar o., andrews b.a. & asenjo j.a. 2008. cloning and fusion expression of a cold-active lipase from marine antarctic origin. enzyme and microbial technology 42, 371–377. pfeffer j., rusnak m., hansen c., rhlid r.b., schmid r.d. & maurer s.c. 2007. functional expression of lipase a from candida antarctica in escherichia coli—a prerequisite for fig. 5 sodium dodecyl sulfate polyacrylamide gel electrophoresis (sdspage) analysis of pcold iii+lip-1452 in escherichia coli bl21 (de3); m, marker; lane 1, uninduced cell of pcold iii+lip-948; lane 2, total protein of pcold iii+lip-1452 after 24-h induction; lane 3, supernatant after supersonic lysis; lane 4, pellet; lane 5, total protein of pcold iii in bl21 after induction; lane 6, uninduced cell of pcold iii. the arrow points to the predicted protein. fig. 6 sodium dodecyl sulfate polyacrylamide gel electrophoresis (sdspage) analysis of pcold iii+lip-948 in escherichia coli bl21 (de3); m, marker; lane 1, pellet; lane 2, supernatant after supersonic lysis; lane 3, total protein of pcold iii+lip-1452 after 24-h induction; lane 4, uninduced cell of pcold iii+lip-948; lane 5, total protein of pcold iii in bl21 after induction; lane 6, uninduced cell of pcold iii. the arrow points to the predicted protein. cloning and expression of cold-active lipases l. xuezheng et al. polar research 29 2010 421–429 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd428 high-throughput screening and directed evolution. journal of molecular catalysis b: enzymatic 45, 62–67. quyen d., schmidt-dannert c., schmid r.d. 1999. high-level formation of active pseudomonas cepacia lipase after heterologous expression of the encoding gene and its modified chaperone in escherichia coli and rapid in vitro refolding. applied and environmental microbiology 65, 787–794. rosenau f. & jaeger k.-e. 2000. bacterial lipases form pseudomonas: regulation of gene expression and mechanisms of secretion. biochimie 82, 1023–1032. ryu h.s., kim h.k., choi w.c., kim m.h., park s.y., han n.s., oh t.k. & lee j.k. 2006. new cold-adapted lipase from photobacterium lipolyticum sp. nov. that is closely related to filamentous fungal lipases. applied microbiology and biotechnology 70, 321–326. sambrook j. & russel d.w. 2001. molecular cloning: a laboratory manual. woodbury, ny: cold spring harbor laboratory press. suzuki t., nakayama t., choo d.w., hirano y., kurihara t., nishino t. & esaki n. 2003. cloning, heterologous expression, renaturation, and characterization of a cold-adapted esterase with unique primary structure from a psychrotroph pseudomonas sp. strain b11-1. protein expression and purification 30, 171–178. yang x.x., lin x.z., bian j., sun x.q. & huang x.h. 2004. screening and phylogenetic analysis of antarctic bacteria producing low-temperature lipase. acta oceanologica sinica 23, 717–723. yang x.x., lin x.z., fan t.j., bian j. & huang x.h. 2008. cloning and expression of lipp, a gene encoding a cold-adapted lipase from moritella sp. 2-5-10-1. current microbiology 56, 194–198. zhang p. & zeng r. 2007. cloning, expression, and characterization of a cold-adapted lipase gene from an antarctic deep-sea psychrotrophic bacterium, psychrobacter sp. 7195. journal of microbial biotechnology 17, 604–610. cloning and expression of cold-active lipasesl. xuezheng et al. polar research 29 2010 421–429 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 429 no job name from the institute’s photo librarypor_177 234 doi:10.1111/j.1751-8369.2010.00177.x this planktonic octopus, photographed by tor ivan karlsen, was collected at 600 m depth at the maud rise seamount in the weddell sea, off dronning maud land, during the 2000/01 norwegian antarctic research expedition. the expedition, which was led by the norwegian polar institute, involved collaborative scientific investigations carried out on land and at sea by a number of norwegian research institutions as well as south african universities. the norwegian polar institute’s photo library preserves some 90 000 polar-related images captured during the last 135 years, including glass plates and slides, stereo images, print photographs and modern digital photographs. images documenting norwegian activities in the arctic and antarctic comprise the bulk of the collection. scanning the older images and registering newer digital ones is an ongoing endeavour. to date, digital versions of over 30 000 pictures are available in a searchable online database at http://sivert.npolar.no/fotoweb/. search words associated with the online images are mostly in the norwegian language; please send an e-mail to bildearkiv@npolar.no for assistance in searching the database. polar research 29 2010 234 © 2010 the author, journal compilation © 2010 blackwell publishing ltd234 http://sivert.npolar.no/fotoweb mailto:bildearkiv@npolar.no por_010.fm 86 polar research 26 (2007) 86 – 87 © 2007 the author book review review of marine mammals: evolutionary biology (second edition), by annalisa berta, james l. sumach & kit m. kovacs (2006). burlington, ma: academic press. 547 pp. isbn 0-12088552-2. the ever-popular field of biology that focuses on mammals that evolved to exploit the marine environment has spawned a suite of texts in the last decade. these have been dedicated to the evolution, systematics, morphology, anatomy, physiology, behaviour, sociobiology, ecology and conservation of this well-studied group. berta et al.’s latest addition to this literature is an impressive advancement of their first edition (2003), and is certainly the only major authored work of its kind [the competing texts are all edited works: reynolds & rommel’s biology of marine mammals (1999); hoelzel’s marine mammal biology: an evolutionary approach (2002); and perrin et al.’s encyclopedia of marine mammals (2002)]. although there is considerable overlap and repetition among texts, berta et al. have deliberately carved out their own niche by focusing heavily on the systematics of the varied taxa this group comprises. the book is unsurpassed as a marine mammal systematics and phylogenetic reference source, with more compiled detail on the evolution of cetaceans, pinnipeds and sirenians than is found in all the other texts combined. indeed, the first 111 pages of this 547-page volume are devoted entirely to systematics and evolution (chapters 1–5), followed by a short chapter on biogeography (this makes up the first section of the book: “evolutionary history”). although absolutely thorough in their treatment of this area, there is a strong emphasis on morphologically based phylogenies, but the lack of genetic evidence presented in the book may be attributed to the general paucity of such data for these taxa. the second section is a more eclectic mix of anatomy, morphology, physiology, population dynamics and behaviour (chapters 6–15), with all but the final two chapters built around the strong evolutionary frame established in the first section. the final section is an appendix detailing the classification, and both current and fossil distribution of marine mammal species, followed by a series of colour plates showing some characteristic species. each chapter also includes an exhaustive list of most major primary literature. the individual chapters are supported by a healthy number of informative schematic drawings, photographs, tables and graphs, although the quality of the black and white photographs and colour plates is variable. i also found that many of the anatomical schematics lacked some important labelling that would have aided the interpretation of the detail provided in the text. that said, most of the line drawings are well crafted and useful for readers possessing a little anatomical education, and the taxonomic comparisons these drawings serve to illustrate are brilliantly achieved. in what is perhaps symptomatic of the field of “marine mammal science” itself, rather than a failing of the book, the authors largely restrict their discussions, comparisons and scientific evidence to marine mammals alone (the correspondence corey j. a. bradshaw, school for environmental research, charles darwin university, darwin, northern territory 0909, australia. email: corey.bradshaw@cdu.edu.au book review polar research 26 (2007) 86 – 87 © 2007 the author 87 preface exposes this perspective in full). although this may appear to be a logical and obvious approach given the title of the book, there is an apparent reluctance to branch out to other taxa that have successfully evolved to exploit the available niches the marine environment offers, and therefore to provide relevant analogies. indeed, there is almost no discussion of marine birds and reptiles (e.g. penguins and marine turtles), some of which have been studied in far greater detail (especially with respect to physiology, reproduction and foraging strategies). this would have broadened the scientific and didactic appeal of the book. apart from the taxonomic peculiarities of marine mammal phylogeny, there is nothing inherently unique about marine mammals that has not been covered in other major disciplines of biology. although many marine mammals provide ideal model systems for the study of major topics in these fields, the artificial, and rather ad hoc, delineation of “marine mammal science” as a specific discipline risks encouraging a lack of appreciation for related and supporting evidence beyond these strict taxonomic confines. the almost cursory addition of otters and polar bears, which are included simply because of their ability to exploit marine resources to some extent, seems somewhat contrived. the book also suffers from a certain bias towards northern hemisphere research, is missing some key references and developments [e.g. atkinson’s (1997) review of pinniped reproductive biology, noad et al.’s (2000) work on whale songs, and butler’s work on diving physiology and metabolism (butler & jones 1997; butler 2004)], and the final chapter on “exploitation and conservation” seems tangential to the theme of the rest of the text. in a book of this size it can also be expected that some typographical and spelling errors will occur, although the occasional use of non-si units and archaic terminology that most biologists now consider inappropriate for the species described (e.g. “rookery”, “cow”, “bull”, etc.) should probably have been avoided. that said, the book has many strengths beyond its comprehensive treatment of evolution and systematics. the inclusion of a chapter on energetics in this edition is a good overview of the field, which has benefited greatly from the study of many model marine mammal species. other highlights include the excellent and concise treatment of respiration and diving physiology (chapter 10), the fascinating account of mysticete feeding behaviour (chapter 12), and the exhaustive description of the evolutionary successes in adapting to the constraints imposed on air-breathing vertebrates living in an aquatic environment. the concise summaries provided at the end of each chapter are also helpful. despite some flaws, the book does represent a good reference source that i will certainly use myself, and it will serve those who teach these themes extremely well. berta et al. deserve to be congratulated for this comprehensive tome—it is a thorough, precise and clearly written reference that will serve admirably those interested in the evolution of marine mammals. corey j. a. bradshaw school for environmental research, charles darwin university, darwin, australia references atkinson s. 1997. reproductive biology of seals. reviews of reproduction 2 , 175–194. butler p.j. 2004. metabolic regulation in diving birds and mammals. respiratory physiology and neurobiology 141 , 297–315. butler p.j. & jones d.r. 1997. physiology of diving of birds and mammals. physiological reviews 77 , 837–899. hoelzel a.r. 2002. marine mammal biology: an evolutionary approach . oxford: blackwell science. noad m.j., cato d.h., bryden m.m., jenner m.n. & jenner k.c.s. 2000. cultural revolution in whale songs. nature 408 , 537. perrin w.f., wursig b. & thewissen j.g.m. (eds.) 2002. encyclopedia of marine mammals . london: academic press. reynolds j.e. & rommel s.a. (eds.) 1999. biology of marine mammals . washington, dc: smithsonian institution press. research note glacier mass balance investigations in the balance years 1984-85 and 1985-86 jon ove hagen a n d olav liestol hagen, j . 0. & liestel, 0. 1987: glacier mass balance investigations in the balance years 1 9 8 4 8 5 and 198s86. polar research 5 n . s . , 261-265. as in previous years norsk polarinstitutt has carried out mass balance investigations on storbreen and hardangerjokulen in mainland norway and on breggerbreen and lovcnbreen in svalbard. more than 20 years of measurements show that the glaciers both in mainland norway and in svalbard are retreating. both in 1985 and in 1986 the glaciers in norway had a negative net balance. a t storbreen the mean annual net balance value 1949-86 is -0.30 m in water equivalents, while o n hardangerj0kulen the mean value 1963-86 is -0.02 m . the two glaciers measured in svalbard also had negative net balance in 1985 and in 1986. both measured glaciers have had negative balance nearly all years since the measurements started in 1966. the mean value is close to 4 0 g/cm2 or 0 . 4 m on both. jon oue hagen and olau liestol. norsk polarinsritutt, p . o . box 158. 1330 oslo lufrhaun, norrr.ap. glaciers in norway storbreen storbreen is situated in jotunheimen in southern norway. mass balance measurements started in 1949. in 1985 the winter accumulation was measured in the beginning of may. the result was 120 g/cm2, which is 85% of the mean value since 1949. the ablation gave a summer balance of 160 g/cm’ which was close to the mean. the net balance result was -40 g/cm2 or -0.4 m water equivalents. in 1986 the winter accumulation measured in the beginning of june was only 105g/cm2, or 1.05 m in water eq., which is one of the lowest values that has ever been measured on this glacier, and it was only 77% of the mean value since 1949. the summer ablation was 137g/cm2 or 1.37111. the result was a negative net balance of -32 g/cm2 or -0.32 rn, while the mean has been -30g/cm2. the net balance result from 1986 is shown in fig. 1. the equilibrium line was then 1770 m a.s.1. the cumulative net balance for the whole period 1949-1986 is then -1104g/cm2 or -11.04m of water layer over the whole glacier. the area of the glacier is 5.3 km2 so the total volume of ice shrinkage is 65 x 106m3. that means that the ice surface on average has lowered 12.3 m over the whole glacier and given an extra quantity of 1.5 x 106m3 water to the river from the glacier every year. a new glacier map in the scale 1 : 10,000 has been constructed from air photos taken in 1985. the former map was constructed in the same scale on the basis of photos from 1968. the volume change during these 17 years could then be cal culated. the mean annual shrinkage of the glacier surface was 0.31 m, which is very close to the measured net balance value. hardangerjv kulen hardangerjekulen is situated south and west of storbreen. both the winter and the summer bal ance on hardangerjekulen usually have the higher values. mass balance has been measured every year since 1963. in 1985 the winter balance was 140g/cm2 or 1.40 m water eq., which is7476 of the mean winter accumulation of 1.90 m. the summer balance was calculated to 190 g/cm2, which is very close to the mean ablation. the result was a net balance of -50g/cm2 or -0.50 rn water eq. the winter accumulation in 1986 was less than normal too, 1.54m, which is 80% of the mean 262 hagen & liestd storbreen 1985 _ _ ~ m a s i i fig. 1. net mass balance at storbreen 1985/86 in relation to height above sea level. table i . spcctfic mass balance in water equivalents (m) for austre br~ggerbreen and midtre lovtnbrcen 1967-1986 year austre brdggerbreen midtre lovenbreen b, h. b, b, b. 1966-67 1 9 6 7 4 1968-69 1969-70 1970-71 1971-72 1972-73 197.3-74 1974-75 1975-76 1976-77 1977-78 1978-79 1979-80 1980-81 1981-82 1982-83 1983-84 1984-85 1985-86 1967-86 0.77 0.57 0.37 0.65 0.95 0.74 0.75 0.78 0.72 0.76 0.75 0.77 0.7s 0.46 0.64 0.70 0.69 0.93 0.98 0 71 0.40 1.42 0.67 1.33 0.91 1.23 1.26 0.82 1.67 1.09 1.17 0.87 1.31 1.48 1.27 1.01 0.68 0.97 1.42 1.48 1.30 1.17 -0.65 -0.10 -0.93 -0.54 -0.58 -0.31 -0.08 -0.92 -0.31 -0.45 -0.11 -0.56 -0.71 -0.52 -0.55 -0.04 -0.27 -0.73 -0.55 -0.32 -0.46 0.48 0.41 0.36 0.70 0.98 0.82 0.70 0.83 0.75 0.80 0.81 0.80 0.83 0.51 0.66 0.75 0.74 0.98 1.06 0.74 0.51 1.25 0.89 1.16 1.20 1.59 1 .w 1.10 0.84 1.29 1.46 1.26 0.97 0.64 0.92 1.42 1.46 1.27 1.11 0.84 -0.03 -0.84 -0.53 -0.46 -0.22 -0.02 -0.89 -0.21 -0.35 -0.04 -0.48 -0.66 -0.43 -0.46 0.02 -0.17 -0.6x -0.48 -0.21 -0.37 glacier mass balance investigations 263 brcggerbreen m a s i 1600 1984 85 loverbreen m a s i i tm 2?i: ‘.o 1.1 q: ~ n w a i e r eq 22 ~ m 0 1.0 20 mwaier eq fig. 2. mass balance variations in relation t o height in 1984/85 on austre breggerbreen and midtrc lovinhreen. 61 ogyerbreen lovenl reen ma.s.1 rea disirihution i i i i i i i 2.0 1.0 10 7.0 mwaler eq m 1.0 0 1.0 20 mwaler eq 11 i , fig. 3. mass balance variations in relation t o height in 1985/86 on austre breggerbreen and midtre lovtnbreen. 264 hagen & liest01 value. the summer melting was also less than normal, and total ablation was 1.60 m . t h e result was a net balance close to zero, -0.06 m . the cumulative net balance of the observation period 1963-86 is -0.50 m . hardangerjskulen is thus nearly in climatic equilibrium. glaciers in svalbard brmggerbreen during the winter 1984/85 the snow accumulation was about 130% of the mean value of the obser a slightly higher deficit t h a n t h e average for the previous 18 years. t h e following winter 1985/86 also had heavy snowfall. the winter balance was 0.98 m , which is the highest winter precipitation since the regis trations started in 1967, 140% of t h e mean. but the summer of 1986 was warm, thc ablation was 1.30m, and thus there was o n e more year of negative net balance, -0.32 m. t h e cumulative net balance since 1967 then becomes -9.23m (see table 1). t h e distribution of snow accurnu lation in 1985-86 is shown in fig. 5 , and t h e mass balance variations related to height can b e seen in fig. 3. , , fig. s. distribution of the snow accumulation on br0g 0 5 0 0 1000 h4 fig. 4 distribution of the snow accumulation on lo\cnbreen in 1985;86 vation period 1967-84, giving a specific winter balance b, = 0.93 m , measured in water equiv alents. the following summer was warmer than normal and the specific summer balance was b, = 1.48 rn. the result was a net balance b, = -0.55 m , which in spite of the great snowfall was glacier mass balance investigations 265 based on air photos from 1977 a glacier map was constructed in the scale 1 : 20,000 with counter interval 10 m. one of the stakes was plotted on the map and surveyed in 1985. the vertical dif ference of the glacier surface was then 5.20111. the cumulative net balance during the same period was 4.95 rn in water equivalents, which is 5.50m of ice. the direct measurements on the map thus agreed well with the annual mass bal ance measurements. loven breen due to a little higher average elevation lovcn breen usually has slightly higher winter accumu lation and a slightly lower ablation in the summer. thus the net balance usually is a little less negative than on br~ggerbreen. these two years have been no exception. in 1985 the winter balance was 0.98 m and the summer balance was 1.46 m , which resulted in a negative net balance of -0.48m. both the accumulation and the ablation were about 30% above the mean values. in the snow-rich winter of 1986 the accumu lation was 1.06m, but in the following warm summer the ablation was 1.27 m. accordingly the net balance was -0.21 m (figs. 2, 3 and 4). the mean net balance on lovcnbreen is then -0.37m, while it is -0.46m on brqggerbreen (table 1). the equilibrium line during these 20 years of measurements is then a little above 400m a.s.l., which is about 100m above an equilibrium line that would keep the net balance at zero. por_026.fm 104 polar research 26 2007 104 – 106 © 2007 the author blackwell publishing incmalden, usaporpolar research0800-03952007 blackwell publishing ltd? 2007262104106original article melting ice—a hot topic?h. s. pedersen f r o m t h e c o n f e r e n c e m e lt i n g i c e — a h o t to p i c ? health in the arctic and climate change henning sloth pedersen 1,2 1 center for arctic environmental medicine, aarhus, denmark 2 primary health care center, nuuk, greenland. e-mail: hsp@gh.gl the arctic environment is like a magnifying glass. many of the hazards stemming from industrial activity in the south tend to concentrate in the north. this is true for ddt, pcb, heavy metals and many other substances that may endanger human health. climate change is yet another example of how the negative impact of industrial activity may be magnified in the arctic region. we know that the increased level of co 2 in the atmosphere is causing global warming, but we do not yet know how rising temperatures may affect individuals biologically. by studying the impact of other forms of pollution we can get an idea of the indirect impact, however. this is likely to include an effect on the overall status of communities, including social life, culture and the availability of animal species that serve as a food supply to the population. greenland eighty per cent of its surface being covered permanently by ice, greenland is particularly vulnerable to climate change. in spite of the harsh living conditions, the island has supported human existence on and off for 6000 years. at the present time, 57 000 people—most of them of inuit origin—live in settlements along the coast. as has always been the case, life here is extremely dependent on the resources of the sea, i.e. fish and sea mammals. my own introduction to greenland was 30 years ago. at first i was a teacher in a small traditional community. my dream was to become a hunter: free and independent in the great arctic. i soon realized, however, that i would not survive for long if i were to depend on my hunting skills. instead i chose to return to the somewhat more comfortable existence as a university student and became a physician. in the past 25 years i have been involved in environmental research in greenland. at the same time i have been holding a position as a family doctor. i also teach environmental and remote area medicine and indigenous health to university students in denmark and australia. globalization of pollution the increased emissions of co 2 are only one of many indicators of industrial activity. almost a billion people worldwide live in poverty, close to the limits of human existence. in order to optimize agricultural production so that a sufficient supply of food may be maintained, pesticides are used. unfortunately, such chemicals may have an adverse effect on human health in the form of increased risk of cancer and reduced fertility; but if the alternative is starvation, there is no real choice. in the same manner, the use of ddt against mosquitoes carrying malaria has its pros and cons. ddt may be able to prevent thousands of deaths every year, but the agent has a proven negative effect on human health as well as on the environment as a whole. similar arguments may be applied to mercury. a heated shelter and access to facilities for preparing a hot meal are inalienable rights. unfortunately, the heating source available to millions of people is coal, which, when burning, emits mercury into the atmosphere. being a very toxic substance, mercury may cause damage to nervous tissues and the brain. it has been estimated that 65 000 tonnes of mercury is deposited in greenland every year with the rain and snow. flame retardants (present in laptops, cell phones, television sets and other electronic equipment to reduce the risk of a fire) are a threat to human health because of their hormone-like qualities. pesticides like ddt, as well as mercury, dioxin and flame retardants have all ended up in the arctic, carried across the globe by winds, currents and through the food chains. because of this globalization of pollution, the indigenous population of the north now holds world record levels of these contaminants. yet another threat to people living in the arctic has now emerged. they may doi:10.1111/j.1751-8369.2007.00026.x h. s. pedersen melting ice—a hot topic? polar research 26 2007 104 – 106 © 2007 the author 105 now be on their way to become some of the primary victims of the effect of co 2 emissions, i.e. global warming. world food web we have www—the world wide web. we have wwf— the world wildlife fund for nature. and we have wfw—the world food web. a food web is made up of all the different plants and animals that have an effect on one another by their feeding habits. a group of food chains meshed together makes a food web. airborne waste products from industrial activity will sooner or later end up in the sea where they will affect the wfw. by each step in the food web, the substances will be concentrated tenfold. consequently, the highest concentrations will be found in animals at the end of the chain, such as whales, seals, turtles, sea birds and polar bears. once introduced into the environment these toxic substances are difficult to get rid of. the half-life in humans is 10–20 years. stored in fat, pesticides are being passed on to babies through the mother’s milk. so we are facing a problem that will persist for generations to come. by eating food that originates in the sea you are actually subjecting yourself to pollution from all around the world. the more seafood you eat, the more of these contaminants you will receive. the obvious answer might be to avoid food originating from the sea alltogether; but in that case you will not get many essential nutrients, such as omega-3 fatty acids, which are needed for the development of the nervous system, the eye and the brain. later in life these nutrients reduce the risk of heart disease, arthritis and diabetes. so you are damned if you do, and damned if you don’t. the answer to this dilemma is a balanced diet containing elements from both land and sea. in greenland, country food (fish, sea mammals, caribou, etc.) represent up to 25% of the diet, with great variations from one settlement to another as well as among individuals. a survey from 2006 shows that local food items only make up 10% of the young and middleaged people’s diet. even so, their intake exceeds the international food safety levels for persistent organic pollutants, pops. instead of eating locally produced food, people in the north are turning to food with a high content of sugar and fat. the market will deliver what people want. local food is healthy in most respects, but contains contaminants. imported food may contain no contaminants, but may cause diabetes and heart disease. this is known as the “arctic dilemma”. change and adaptation human beings possess a strong ability to adapt. this ability is being put to the test by the rapid cultural and environmental changes that are taking place, not least in the arctic. the genes cannot keep up with rapid change. rapid change stresses the sociocultural basis. rapid dietary change can lead to diabetes and heart disease. unemployment can lead to abuse, violence and social isolation. migration to urban areas leads to loss of culture and identity. inuit, as well as other indigenous peoples, have been exposed to massive changes. one or two generations ago they were extremely physically active: depending on hunting and fishing for their survival. the food supply was not always stable. genetically they adapted by developing the ability to store energy in the form of fat. this genetic advantage has now turned into a liability, however. life nowadays does not demand much physical activity, and food is always available. the high-sugar, saturated fat diet that now prevails leads to obesity and diabetes, which is three times more common in greenland than in denmark. marginalization rapid change poses the danger of marginalizing those who cannot keep up. the ensuing social gap and poverty leads to a higher risk of developing diseases—any kind of disease, including infections, cancers and diabetes. when the social gap is widened in a society we always see a higher rate of violence, homicide, suicide, abuse and mental disorders. this has been documented by several reports from the (world health organization (who). among inuit in greenland and canada the suicide rate has exploded from a level close to zero in the 1970s to 10% of all deaths today. these are regions that have gained increased political independence and have improved their economies markedly; but the social gap has widened leading to a variety of disorders, including, crime, unemployment, violence, abuse, homicide, suicide, etc. teenage pregnancies, tuberculoses, venereal diseases and mental disorders have also become more prevalent. cultures are not static. cultures and people must change in order to survive. cultures, as well as genes, need challenges in order to maintain their strength. to slow down the rapid pace of change is probably difficult; instead, we must take care of the people at risk. in order to prevent or resist the negative impact of change, research and monitoring are needed. immediate threats, such as the threat of a diabetes epidemic, are easy to relate to. it is much more difficult to attract attention from politicians and others to the risk for environmental hazards because the impact—impaired fertilization, immune system defects, cancer—is not as obvious, and often can only be detected over generations. 106 polar research 26 2007 104 – 106 © 2007 the author melting ice—a hot topic? h. s. pedersen people living in remote areas such as the arctic are not only subjected to pollution of the body, but also pollution of the mind. through television, the internet, magazines and other media they receive a high dose of western pop culture. advertising and soap operas are causing dramatic change to life in the far north, to the inuit culture. an inuit politician once likened the effect of television to that of a neutron bomb: it ruins the mind but leaves the body intact. unfortunately this is not even true, because the body is affected, too—by lack of physical activity and by fast food, which seems to be an indispensible companion to watching tv. rapid transition climate change in itself may not be a threat to human health; but the rapid cultural changes that may follow in its wake may be. arctic cultures and societies are at major risk of extinction. the individuals that make up those cultures may survive as individuals, but they may lose their identity, their social and cultural roots, thereby becoming marginalized and more prone to developing disease. the problem is not change itself: it is the pace at which it takes place. human beings need time—often several generations—to adapt to new circumstances. climate change may take place too rapidly for people to adjust. prevention of diseases needs to be looked upon from a social, economic and cultural point of view. since world war ii the health systems in the western world have been dominated by enormous hospitals that attract most of the resources allocated for fighting diseases. there is much less prestige and economic interest in preventing diseases. medical science is based on biology. this is in many ways a useful approach, but the weakness is that the social, historical and cultural causes of diseases are not addressed. treatment of diseases is based on biology, using medicine or surgery. to prevent diseases requires an understanding of cultural and social habits. responsibility in some ways the environmental problems that are facing the arctic region today are the result of the uneven distribution of wealth in the world. it is easy to feel angry when realizing that the traditional food supply of the 160 000 inuit living in the circumpolar region is contaminated with pesticides. the use of chemicals elsewhere in the world makes it necessary to recommend restrictions on the intake of food that has constituted the inuit population’s main diet for thousands of years. the other side of the coin is that pesticides make it possible for millions of people elsewhere in the world to grow enough food for their survival. in the same manner, it seems unfair that the inuit are the victims of mercury pollution originating far from the arctic region; but coal is the only energy source available to millions of people. if third world farmers were better off, if coal users had an alternative, the arctic region would be a cleaner place. in my opinion, it is the responsibility of rich countries to correct this inequality. now the region is facing yet another threat, this time from global warming. it is time to develop a global approach for fighting not only pollution, but also poverty, which is part of the equation. much human suffering can probably be avoided by keeping reigns on the pace of change, and by monitoring the negative effects of change so that undesirable developments can be corrected or avoided. it is, in short, time for sustainable development, not only physically but also sociologically, socially and culturally. morphology, geology and oceanography of the hinlopen strait and trough, svalbard, norway stephanie pfirman a n d john d. milliman pfirman, s. & milliman, j . d. 1987: morphology, geology and oceanography of the hinlopen strait and trough, svalbard, norway. polar research 5 n . s . , 297-298. stephanie e r m a n , geologisch-palaontologisches institut und museum, christian-albrechts uniuersitat, kiel, f.r.g.; john d . milliman, woo& hole oceanographic institution, woo& hole, ma. u.s.a. the hinlopen strait and trough (fig. 1) form a strikingly linear nw-se feature, extending from svalbard across the shelf and onto the arctic sea slope. maximum water depths exceed 400111, but a number of sills, some presumably structural and others sedimentary. divide the strait/trough into a series of basins. acoustically transparent sediment, which locally is thicker than 60 m in some basins, is probably late quaternary in age, the upper 1-5m are holocene, and were probably influenced by atlantic water from the arctic extension of the west spitsbergen current. although the strait appears to be at least partly fault-related, the few available seismic data from the trough show no evidence of faulting. the only reasonable alternative fluvial excavation and glacial modification seems likely if it occurred along a zone (or zones) of structural weakness or geological contrast. while glaciers may have occupied part or all of the trough during glacial epochs, we see no sign of sediment accumulation on the outermost shclf and upper slope, unlike the sediment fans that characterize other cross-shelf troughs in the arctic; presumably little or no sediment was discharged onto the arctic slope from the hinlopen trough. 298 s . pfirrnan & j . d . milliman fig 1 the hinlopen strait and trough with respect to northern svalbard contours in meters doi:10.3402/polar.v34.23225 r e s e a r c h / r e v i e w a r t i c l e protists in the polar regions: comparing occurrence in the arctic and southern oceans using pyrosequencing christian wolf, estelle kilias & katja metfies department of bioscience, alfred wegener institute helmholtz centre for polar and marine research, am handelshafen 12, de-27570 bremerhaven, germany keywords 18s rdna; bipolar; next-generation sequencing; phytoplankton; polar regions; protist distribution correspondence christian wolf, department of bioscience, alfred wegener institute helmholtz centre for polar and marine research, am handelshafen 12, de-27570 bremerhaven, germany. e-mail: christian.wolf@awi.de abstract in the ongoing discussion of the distribution of protists, whether they are globally distributed or endemic to one or both of the polar regions is the subject of heated debate. in this study, we compared next-generation sequencing data from the arctic and the southern oceans to reveal the extent of similarities and dissimilarities between the protist communities in the polar regions. we found a total overlap of operational taxonomic units (otus) between the two regions of 11.2%. on closer inspection of different taxonomic groups, the overlap ranged between 5.5% (haptophytes) and 14.5% (alveolates). within the different groups, the proportion of otus occurring in both regions greatly differed between the polar regions. on the one hand, the overlap between these two regions is remarkable, given the geographical distance between them. on the other hand, one could expect a greater overlap of otus between these regions on account of the similar environmental conditions. the overlap suggests a connection between the polar regions for at least certain species or that the evolutionary divergence has been slow, relative to the timescales of isolation. the different proportions of common otus among the groups or regions may be a result of different life cycle strategies or environmental adaptations. to access the supplementary material for this article, please see supplementary files under article tools online. the distribution of microbes is the subject of much debate. for prokaryotes, there is a consensus for a largely global dispersal of species (bano et al. 2004; pommier et al. 2007). for the eukaryotic fraction (protists), global distribution versus endemism is heatedly discussed (finlay & fenchel 2004; lachance 2004; medlin 2007). there are bipolar species that do not occur in intervening latitudes (sul et al. 2013). the investigation of bipolarity among microbes recently gained more interest. jungblut et al. (2012) found a limited overlap between antarctic and arctic microbial mat communities. pawlowski et al. (2008) found that populations of monothalamous foraminifers from the arctic and antarctic differed genetically and represented distinct species. the polar oceans are subject to similar physical extremes, such as 24 h of sun in the polar summer and 24 h of darkness during the polar winter (for a great portion of the southern ocean). low temperatures at the beginning of the polar winter lead to sea-ice formation. during the polar spring, ice algal blooms followed by ice melt and phytoplankton production support organisms higher in the food chain. one basic difference between the two oceans is the freshwater input (ghiglione et al. 2012). surrounded by landmasses, the arctic ocean receives freshwater from several large rivers and glacial meltwater. in contrast, the southern ocean surrounds the continent of antarctica and is supplied with freshwater only through glacial meltwater. here, we present a comparison of next-generation sequencing data from the arctic and southern oceans. we want to answer two questions. (i) are there operational taxonomic units (otus) that are present in both polar research 2015. # 2015 c. wolf et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2015, 34, 23225, http://dx.doi.org/10.3402/polar.v34.23225 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/23225/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23225/0 http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/23225 http://dx.doi.org/10.3402/polar.v34.23225 polar oceans and if so in what proportion? (ii) are there any differences in the proportion of otus occurring in both polar regions between different taxonomic groups and the two regions? since we did not include samples from temperate regions, we are aware that we are not able to draw definitive conclusion about true bipolarity. therefore, the otus found in both regions could also have a global distribution. however, our data set can be compared with other pyrosequencing data sets to complete the information about the distribution of the otus. material and methods study sites and sampling for the analysis, we used eight surface water samples from the arctic ocean (fig. 1a) and 10 surface water samples from the pacific sector of the southern ocean (fig. 1b). all samples are part of other studies containing detailed information about the sampling procedure and data handling (wolf et al. 2013; kilias et al. 2014; wolf et al. 2014). all samples were collected in polar waters (north of 798n or south of 668s) and in late summer. arctic ocean samples were taken at the surface with 12 l niskin bottles deployed on a rosette. the southern ocean samples were collected using the ship pumping system (membrane pump), located at the bow at 8 m depth below the surface. all samples were immediately fractionated by filtering them on isopore membrane filters (milipore, billerica, ma, usa) with a pore size of 10 mm, 3 mm and 0.4 mm (arctic ocean) or 0.2 mm (southern ocean). filters were stored at �808c until analysis in the laboratory. dna extraction, polymerase chain reaction amplification and 454-pyrosequencing the dna was extracted with the e.z.n.a. tm sp plant dna kit (omega bio-tek, norcross, ga, usa) as described by wolf et al. (2014). for subsequent 454pyrosequencing, the v4 region of the 18s rrna gene was amplified with the primer set 528f (5?-gcg gta att cca gct cca a-3?) and 1055r (5?-acg gcc atg cac cac cac cca t-3?) (modified from elwood et al. 1985). details about the procedure, the polymerase chain reaction (pcr) reaction mixture and the reaction conditions were described by kilias et al. (2013). pyrosequencing was performed on a genome sequencer flx system (roche, basel, switzerland) by gatc biotech ag (konstanz, germany). data analysis raw sequence reads were processed as described by wolf et al. (2014) to obtain high-quality reads. briefly, reads shorter than 300 bp and longer than 670 bp, reads with more than one uncertain base (n), chimeric reads, and reads belonging to metazoans were removed. the remaining high-quality reads of all 18 samples were placed into a reference tree, containing about 1250 highquality sequences of eukarya from the silva reference database (ssu ref 111) (quast et al. 2013), using the phyloassigner pipeline (vergin et al. 2013). reads were 180°w 180°w (a) (b) 0° 0° 80°n 70°n 60°n 60°s 70°s 80°s greenland arctic ocean laptev sea antarctica amundsen sea ross sea 9 0 °w 9 0 °e 9 0 °w 9 0 °e fig. 1 locations of sampling sites (white dots) in the (a) arctic ocean and the (b) southern ocean. occurrence of protists at both poles c. wolf et al. 2 (page number not for citation purpose) citation: polar research 2015, 34, 23225, http://dx.doi.org/10.3402/polar.v34.23225 http://www.polarresearch.net/index.php/polar/article/view/23225 http://dx.doi.org/10.3402/polar.v34.23225 divided into major taxonomic groups and for each group, the reads were clustered (furthest neighbour algorithm) into otus at the 98% similarity level using the dnastar software lasergene 10. in the past, the 97% similarity level has tended to be the most suitable to reproduce original eukaryotic diversity (behnke et al. 2011) and also has the effect of bracing most of the sequencing errors (kunin et al. 2010). however, the similarity level is still under debate. the known intragenomic ssu polymorphism level strongly varies between different taxonomic groups. in dinoflagellate species it can range up to 2.9% (miranda et al. 2012). consequently, different taxonomic groups may require different similarity levels, which hampers the choice for an appropriate similarity level for environmental samples. we took a more conservative approach and used the 98% similarity level, as previously used for eukaryotes by comeau et al. (2011), to avoid an overestimation of similarities between the two polar regions. otus comprised of only one sequence (singletons) were removed. consensus sequences were generated for each otu and their taxonomical affiliation was determined using the phyloassigner pipeline and individual reference databases for each major taxonomic group, containing about 382 (haptophytes) to 9052 (alveolates) high-quality sequences of the particular group from the silva reference database (ssu ref 111). the compiled reference database is available on request in arb-format. the raw sequences were deposited at genbank’s short read archive (sra) under accession numbers sra056811, sra057133 and sra064761. results we compared a total of 590 616 high-quality reads. the number of reads for both regions was quite similar with 317 478 for the southern ocean and 273 138 for the arctic ocean. the classification of the reads into the major taxonomic groups resulted in 114 292 reads for haptophytes, 42 556 reads for chlorophytes, 144 914 reads for stramenopiles and 256 823 reads for alveolates. the remaining 32 031 reads affiliated with other groups (e.g., cryptophytes, rhodophytes) or their affiliation was uncertain (the position in the database tree was too high to be assigned to one group). the number of reads for each group greatly differed between the two regions (table 1). about 35�53% of all reads were identified as singletons and excluded for the final comparison. we determined 23 637 otus in all samples, of which 11.2% occurred in both polar regions (fig. 2a). for the haptophytes, we found nearly twice the number of otus in the southern ocean than in the arctic ocean (fig. 2b). the overlap in haptophyte otus between the two regions was 5.5%. the number of chlorophyte otus also differed strongly between both regions (fig. 2c). the arctic ocean presented a 10-fold higher number of chlorophyte otus compared to the southern ocean. the proportion of chlorophyte otus occurring in both regions was 8.1%. in contrast, the stramenopiles showed five times more otus in the southern ocean (fig. 2d). the overlap in stramenopile otus between the two regions was 8%. among the alveolates, the number of determined otus in the two regions was very similar (fig. 2e). the overlap of alveolate otus between the southern ocean and arctic ocean (14.5%) was greatest among all four groups. only two otus that occurred in both regions were also abundant (otus with �1% of total reads) in both regions (fig. 3a�d). one of these otus affiliated with the alveolates (unc. alveolate) and one with the genus micromonas (mamiellales 1). all other otus occurring in both regions originated from the rare biosphere (otus with b1% of total reads) in at least one region. the proportion of common otus (occurring in both regions) among haptophytes was nearly twice as high in the arctic ocean (fig. 4). in contrast, the proportion of common otus among chlorophytes was four times greater in the southern ocean. within the chlorophytes, the mamiellales showed a common otu proportion of 65% in the southern ocean, whereas in the arctic ocean the proportion was only 9%. the proportion of common otus among the stramenopiles was three times higher in the arctic ocean. here, the diatoms showed a 10-fold and the pelagophytes a seven-fold higher proportion of common otus. for the marine stramenopiles (mast), we determined similar proportions of common otus in both regions. overall, alveolates showed similar common otu proportions in both regions. the biggest differences between the two regions were constituted by syndiniales. here, the proportions of common otus were always higher in the southern ocean (up to 10-fold). the abundant otus were compared with the national center for biotechnology information nucleotide database using the basic local alignment search tool (blast) (altschul et al. 1990) and the best match originating from the warmest region was used to provide an insight table 1 number of reads and defined operational taxonomic units (otus) assigned to the major taxonomic groups. arctic ocean total reads/ defined otus southern ocean total reads/ defined otus haptophytes 14 682/1106 58 624/2011 chlorophytes 22 160/1133 2674/264 stramenopiles 15 077/1668 78 668/5524 alveolates 57 048/7452 62 768/7117 c. wolf et al. occurrence of protists at both poles citation: polar research 2015, 34, 23225, http://dx.doi.org/10.3402/polar.v34.23225 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23225 http://dx.doi.org/10.3402/polar.v34.23225 into their potential global distribution (supplementary table s1). the majority of haptophyte otus (63%) and nearly all otus assigned to phaeocystaceae (92%) were restricted to the polar regions. among the stramenopiles, the diatoms were the most limited to the polar regions (60%), whereas the rest were largely also found in more temperate regions. the chlorophyte otus were mostly associated with temperate representatives, except for the mamiellales otus, which were restricted to polar regions. most of the representatives affiliated with the otus belonging to alveolates originated from temperate and tropic regions and only 25% were restricted to polar regions. discussion in the present study, we compared pyrosequencing data sets from both polar oceans. samples were taken in both regions from the surface during summer, which allows for a suitable comparison as the sequencing resulted in similar read counts. we focused our comparison on the two polar regions and on the otu level. we decided against calculating diversity indices in our study because the numeration of single organisms is a prerequisite. the results of 454-pyrosequencing data are semi-quantative and due to the differences in gene copy numbers among different species (zhu et al. 2005) we cannot state that every read represents one organism. our first question, whether a number of otus is present in both polar oceans, was positively answered. one-tenth of the revealed otus were found in both areas. given that a large distance geographically separates these two marine regions, this overlap between them is remarkable. on the other hand, considering the similar environmental conditions, one could expect a greater overlap of otus between these regions. this relatively small overlap could be explained by the restricted sampling opportunity in all four groups (b) (c) (d) (e) 12 278 (a) southern ocean (14 916) haptophytes chlorophytes southern ocean (2011) southern ocean (5524) southern ocean (264) 1858 4990 534 1134 stramenopiles alveolates arctic ocean (1106) arctic ocean (1668) southern ocean (7117) arctic ocean (7452) 153 953 159 5271 1846 5606 105 1028 arctic ocean (11 359) arctic ocean (1133) 2638 8721 fig. 2 venn diagrams showing the overlap of operational taxonomic units (98% similarity level) between the two polar regions for (a) all four groups; (b) haptophytes; (c) chlorophytes; (d) stramenopiles; and (e) alveolates. occurrence of protists at both poles c. wolf et al. 4 (page number not for citation purpose) citation: polar research 2015, 34, 23225, http://dx.doi.org/10.3402/polar.v34.23225 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23225/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23225/0 http://www.polarresearch.net/index.php/polar/article/view/23225 http://dx.doi.org/10.3402/polar.v34.23225 the southern ocean, confined only to the pacific sector while our arctic ocean samples covered different water masses. including samples from the atlantic sector of the southern ocean would probably increase the detection of common otus between both regions. another consideration is that the samples may not have been exhaustively sequenced, resulting in a lower number of available sequences for overlapping possibilities. the detected common otus suggest that there may be a connection between the polar regions for at least certain species. dispersion from one pole to the other may happen via long-range transport processes, including wind and the ocean conveyor belt. such long-distance transportation has been reported for bacteria (hughes et al. 2004) and land plants (muñoz et al. 2004). shipping traffic may also account for the dispersal of protists across the oceans, principally for species that form spores or resting cysts (jungblut et al. 2012). darling et al. (2000) showed that trans-tropical gene flow between arctic and antarctic populations of planktonic foraminifers must have occurred in the past. the exchange might have happened during cooling periods associated with glacial cycling. in warmer periods, the tropical ocean acts as a barrier, promoting diversification (darling et al. 2004). this may also be true for certain species of haptophytes, chlorophytes, stramenopiles and alveolates, which we have investigated. the slow evolutionary divergence, relative to the timescales of isolation (jungblut et al. 2012) could also partly explain the overlap of otus between the two polar regions. therefore, in the future, lower similarities between protist communities in both polar regions might be observed. another outcome from our analysis was that most similarities between the two polar regions were found in bicoeceae chrysophyceae dictyochophyceae dictyochophyceae dictyochophyceae dictyochophyceae dictyochophyceae pelagophyceae dolichomastigales dolichomastigales mamiellales mamiellales mamiellales halosphaeraceae halosphaeraceae halosphaeraceae halosphaeraceae halosphaeraceae halosphaeraceae halosphaeraceae halosphaeraceae phaeocystaceae 1 (a) (b) (c) (d) phaeocystaceae 2 phaeocystaceae 3 phaeocystaceae 4 phaeocystaceae 5 phaeocystaceae 6 phaeocystaceae 7 phaeocystaceae 8 phaeocystaceae 9 phaeocystaceae 10 phaeocystaceae 11 phaeocystaceae 12 prymnesiaceae 1 prymnesiaceae 2 prymnesiaceae 3 prymnesiaceae 4 prymnesiaceae 5 pavlovophycea incertae sedi dinophyceae dinophyceae dinophyceae dinophyceae dinophyceae syndiniales syndiniales syndiniales syndiniales ciliophora ciliophora ao so ao so ao so ao 1 2 1 2 3 1 2 3 4 5 6 7 8 1% 1% 1 2 3 4 5 mast1a mast1b diatom 1 diatom 2 diatom 3 diatom 4 diatom 5 diatom 6 diatom 7 diatom 8 diatom 9 diatom 10 mast1c 1 mast1c 2 mast2 1 mast3 1 mast3 1 mast3 2 mast7 1 mast7 2 mast7 3 mast8 1 mast8 2 unc. alveolate group i 1 group i 2 group ii 1 group ii 2 1 2 6% 12% 1% 6% 12% 15% 31% 1% 35% 69% so 1 2 3 4 5 fig. 3 colour-coded matrix plot, illustrating the relative read abundance of abundant operational taxonomic units (otus) (abundance ]1%) for (a) haptophytes; (b) stramenopiles; (c) chlorophytes; and (d) alveolates in the arctic ocean (ao) and the southern ocean (so). white boxes indicate the absence of the respective otu. the green stars indicate the two otus that occurred in the abundant biosphere in both regions. c. wolf et al. occurrence of protists at both poles citation: polar research 2015, 34, 23225, http://dx.doi.org/10.3402/polar.v34.23225 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23225 http://dx.doi.org/10.3402/polar.v34.23225 the rare biosphere, suggesting that ecosystem functioning in both polar regions is supported by different species. no statements about temporal patterns can be drawn from our investigation because we only had a snapshot during polar summers in both regions. the rare biosphere might serve as a seed pool and certain species might become abundant during other times of the year when environmental conditions are favourable. rarity may also be an evolutionary trait (logares et al. 2014) and the avoidance of competition, predation, and parasitism might be advantages of a low-abundance life (pedrós-alió 2006). in a previous study investigating protist diversity in the central arctic ocean (kilias et al. 2014), dinoflagellates (i.e., syndiniales), haptophytes (i.e., phaeocystis sp.) and chlorophytes (i.e., micromonas sp.) dominated the assemblages (supplementary table s2). samples with similar sea-ice concentrations showed a high accordance in their community composition, indicating that sea ice has a stronger influence than nutrient availability. in another previous study focusing on protist community structure in the southern ocean (wolf et al. 2014), dinoflagellates, haptophytes and diatoms dominated the assemblages (supplementary table s3). here, we found that different water masses harboured different protist communities: small-sized protists dominated the northern part of the investigated area and big-sized protists the south. in the amundsen sea, we observed a high occurrence of dinoflagellates, haptophytes and diatoms (wolf et al. 2013) (supplementary table s4). we found characteristic offshore and inshore protist communities, with dinoflagellates more abundant offshore and diatoms inshore. in the current study, the southern ocean was readily distinguishable from the arctic ocean in terms of the number of otus for each group. we found more otus affiliated with haptophytes and stramenopiles in the southern ocean, which is consistent with high abundances of phaeocystis and diatoms found in earlier studies (alderkamp et al. 2012; mills et al. 2012; wolf et al. 2013). high abundances of chlorophytes were reported in the arctic ocean (lovejoy et al. 2006; lovejoy et al. 2007), which agrees with the higher amounts of otus belonging to this group in the arctic ocean that we found. in both regions, we found similar numbers of otus affiliated with alveolates. this last group consists of dinoflagellates, syndiniales and ciliates and is mostly heterotrophic, mixotrophic or parasitic (sherr & sherr 2007). this indicates that the distribution of alveolates may not be as influenced by nutrient availability as that of other protists, which jibes with their presence in the polar regions. haptophytes chlorophytes diatoms mamiellales southern ocean arctic ocean pelagophytes mast syndinales group i syndinales group ii syndinales group iii 0 10 20 30 proportion (%) 40 50 60 70 alveolates stramenopiles fig. 4 proportion of common operational taxonomic units (occurring in both polar regions) within the different groups. occurrence of protists at both poles c. wolf et al. 6 (page number not for citation purpose) citation: polar research 2015, 34, 23225, http://dx.doi.org/10.3402/polar.v34.23225 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23225/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23225/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23225/0 http://www.polarresearch.net/index.php/polar/article/view/23225 http://dx.doi.org/10.3402/polar.v34.23225 our second question, whether there are any differences in the proportion of otus occurring in both regions between different taxonomic groups and the regions, was also positively answered. alveolates showed the highest proportion of common otus, fitting well to the fact that they form resting cysts (e.g., bravo et al. 2010), which are more easily transported over long distance across the oceans. also, as stated previously, the distribution of alveolates is less affected by abiotic factors, in contrast to autotrophs. in general, the polar region that showed the lower number of otus (within one group) had the highest proportion of common otus. we suggest that the region with the higher number of otus could serve as source for dispersion across the ocean. another explanation may be that the diversification of species goes faster in the region with the larger number of otus. the syndiniales, a parasitic group within the dinoflagellates (guillou et al. 2008), showed more otus restricted to the arctic samples. we found representatives of the syndiniales group i�v in the arctic ocean, but only group i�iii in the southern ocean (data not shown). our findings suggest that the conditions for syndiniales (e.g., host availability) in the north have led to a greater diversification. our first insight into the potential global distribution of the investigated abundant otus showed that most of the otus restricted to polar regions were autotrophic (e.g., phaeocystaceae, diatoms, mamiellales). in contrast, most of the heterotrophs (e.g., mast, alveolates) also showed similarities to representatives from warmer regions. this strengthens our suggestion that heterotrophs are less affected by abiotic factors and are not as limited in their global distribution as autotrophs. most of the otus revealed in our study were restricted to one polar region. the limited occurrence is confirmed by other studies investigating microbial distribution. logares et al. (2012) found that not all masts are equally represented at each geographic location they investigated. edgcomb et al. (2013) found distinct communities of eukaryotes in microbialites from australia and bahamas. acknowledgements this study was accomplished within the young investigator group planktosens (vh-ng-500), funded by the initiative and networking fund of the helmholtz association. we thank the captain and crew of the rv polarstern for their support during the cruises. we are grateful to a. nicolaus and k. oetjen for technical support in the laboratory. references alderkamp a.c., mills m.m., van dijken g.l., laan p., thuroczy c.e., gerringa l.j.a., de baar h.j.w., payne c.d., visser r.j.w., buma a.g.j. & arrigo k.r. 2012. iron from melting glaciers fuels phytoplankton blooms in the amundsen sea (southern ocean): phytoplankton characteristics and productivity. deep-sea research part i 71�76, 32�48. altschul s.f., gish w., miller w., myers e.w. & lipman d.j. 1990. basic local alignment search tool. journal of molecular biology 215, 403�410. bano n., ruffin s., ransom b. & hollibaugh j.t. 2004. phylogenetic composition of arctic ocean archeal assemblages and comparison with antarctic assemblages. applied environmental microbiology 70, 781�789. behnke a., engel m., christen r., nebel m., klein r.r. & stoeck t. 2011. depicting more accurate pictures of protistan community complexity using pyrosequencing of hypervariable ssu rrna gene regions. environmental microbiology 13, 340�349. bravo i., fraga s., figueroa r.i., pazos y., massanet a. & ramilo i. 2010. bloom dynamics and life cycle strategies of two toxic dinoflagellates in a coastal upwelling system (nw iberian peninsula). deep-sea research part ii 57, 222�234. comeau a.m., li w.k.w., tremblay j.e., carmack e.c. & lovejoy c. 2011. arctic ocean microbial community structure before and after the 2007 record sea ice minimum. plos one 6, e27492, doi: 10.1371/journal.pone.0027492. darling k.f., kucera m., pudsey c.j. & wade c.m. 2004. molecular evidence links cryptic diversification in polar planktonic protists to quaternary climate dynamics. proceedings of the national academy of sciences of the united states of america 101, 7657�7662. darling k.f., wade c.m., stewart i.a., kroon d., dingle r. & brown a.j.l. 2000. molecular evidence for genetic mixing of arctic and antarctic subpolar populations of planktonic foraminifers. nature 405, 43�47. edgcomb v.p., bernhard j.m., summons r.e., orsi w., beaudoin d. & visscher p.t. 2013. active eukaryotes in microbialites from highborne cay, bahamas, and hamelin pool (shark bay), australia. the isme journal 8, 418�429. elwood h.j., olsen g.j. & sogin m.l. 1985. the small-subunit ribosomal rna gene sequences from the hypotrichous ciliates oxytricha nova and stylonychia pustulata. molecular biology and evolution 2, 399�410. finlay b.j. & fenchel t. 2004. cosmopolitan metapopulations of free-living microbial eukaryotes. protist 155, 237�244. ghiglione j.f., galand p.e., pommier t., pedrós-alió c., maas e.w., bakker k., bertilson s., kirchman d.l., lovejoy c., yager p.l. & murray a.e. 2012. pole-to-pole biogeography of surface and deep marine bacterial communities. proceedings of the national academy of sciences of the united states of america 109, 17633�17638. guillou l., viprey m., chambouvet a., welsh r.m., kirkham a.r., massana r., scanlan d.j. & worden a.z. 2008. widespread occurrence and genetic diversity of marine c. wolf et al. occurrence of protists at both poles citation: polar research 2015, 34, 23225, http://dx.doi.org/10.3402/polar.v34.23225 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23225 http://dx.doi.org/10.3402/polar.v34.23225 parasitoids belonging to syndiniales (alveolata). environmental microbiology 10, 3349�3365. hughes k.a., mccartney h.a., lachlan-cope t.a. & pearce d.a. 2004. a preliminary study of airborne microbial biodiversity over peninsular antarctica. cellular and molecular biology 50, 537�542. jungblut a.d., vincent w.f. & lovejoy c. 2012. eukaryotes in arctic and antarctic cyanobacterial mats. fems microbiology ecology 82, 416�428. kilias e., kattner g., wolf c., frickenhaus s. & metfies k. 2014. a molecular survey of protist diversity through the central arctic ocean. polar biology 37, 1271�1287. kilias e., wolf c., nöthig e.m., peeken i. & metfies k. 2013. protist distribution in the western fram strait in summer 2010 based on 454-pyrosequencing of 18s rdna. journal of phycology 49, 996�1010. kunin v., engelbrektson a., ochman h. & hugenholtz p. 2010. wrinkles in the rare biosphere: pyrosequencing errors can lead to artificial inflation of diversity estimates. environmental microbiology 12, 118�123. lachance m.a. 2004. here and there or everywhere? bioscience 54, 884. logares r., audic s., bass d., bittner l., boutte c., christen r., claverie j., decelle j., dolan j.r., dunthorn m., edvardsen b., gobet a., kooistra w.h.c.f., mahé f., not f., ogata h., pawlowski j., pernice m.c., romac s., shalchian-tabrizi k., simon n., stoeck t., santini s., siano r., wincker p., zingone a., richards t.a., de vargas c. & massana r. 2014. patterns of rare and abundant marine microbial eukaryotes. current biology 24, 813�821. logares r., audic s., santini s., pernice m.c., de vargas c. & massana r. 2012. diversity patterns and activity of uncultured marine heterotrophic flagellates unveiled with pyrosequencing. the isme journal 6, 1823�1833. lovejoy c., massana r. & pedrós-alió c. 2006. diversity and distribution of marine microbial eukaryotes in the arctic ocean and adjacent seas. applied environmental microbiology 72, 3085�3095. lovejoy c., vincent w.f., bonilla s., roy s., martineau m.j., terrado r., potvin m., massana r. & pedrós-alió c. 2007. distribution, phylogeny, and growth of cold-adapted picoprasinophytes in arctic seas. journal of phycology 43, 78�89. medlin l.k. 2007. if everything is everywhere, do they share a common gene pool? gene 406, 180�183. mills m.m., alderkamp a.c., thuroczy c.e., van dijken g.l., laan p., de baar h.j.w. & arrigo k.r. 2012. phytoplankton biomass and pigment responses to fe amendments in the pine island and amundsen polynyas. deep-sea research part i 71�76, 61�76. miranda l.n., zhuang y.y., zhang h. & lin s. 2012. phylogenetic analysis guided by intragenomic ssu rdna polymorphism refines classification of ‘‘alexandrium tamarense’’ species complex. harmful algae 16, 35�48. muñoz j., felicı́simo á.m., cabezas f., burgaz a.r. & martı́nez i. 2004. wind as a long-distance dispersal vehicle in the southern hemisphere. science 304, 1144�1147. pawlowski j., majewski w., longet d., guiard j., cedhagen t., gooday a.j., korsun s., habura a.a. & bowser s.s. 2008. genetic differentiation between arctic and antarctic monothalamous foraminiferans. polar biology 31, 1205�1216. pedrós-alió c. 2006. marine microbial diversity: can it be determined? trends in microbiology 14, 257�263. pommier t., canbäck b., riemann l., bostrom k.h., simu k., lundberg p., tunlid a. & hagstrom a. 2007. global patterns of diversity and community structure in marine bacterioplankton. molecular ecology 16, 867�880. quast c., pruesse e., yilmaz p., gerken j., schweer t., yarza p., peplies j. & glöckner f.o. 2013. the silva ribosomal rna gene database project: improved data processing and webbased tools. nucleic acids research 41, d590�d596. sherr e.b. & sherr b.f. 2007. heterotrophic dinoflagellates: a significant component of microzooplankton biomass and major grazers of diatoms in the sea. marine ecology progress series 352, 187�197. sul w.j., oliver t.a., ducklow h.w., amaral-zettler l.a. & sogin m.l. 2013. marine bacteria exhibit a bipolar distribution. proceedings of the national academy of sciences of the united states of america 110, 2342�2347. vergin k.l., beszteri b., monier a., thrash j.c., temperton b., treusch a.h., kilpert f., worden a.z. & giovannoni s.j. 2013. high-resolution sar11 ecotype dynamics at the bermuda atlantic time-series study site by phylogenetic placement of pyrosequences. international society for microbial ecology journal 7, 1322�1332. wolf c., frickenhaus s., kilias e.s., peeken i. & metfies k. 2013. regional variability in eukaryotic protist communities in the amundsen sea. antarctic science 25, 741�751. wolf c., frickenhaus s., kilias e.s., peeken i. & metfies k. 2014. protist community composition in the pacific sector of the southern ocean during austral summer 2010. polar biology 37, 375�389. zhu f., massana r., not f., marie d. & vaulot d. 2005. mapping of picoeucaryotes in marine ecosystems with quantitative pcr of the 18s rrna gene. fems microbiology ecology 52, 79�92. occurrence of protists at both poles c. wolf et al. 8 (page number not for citation purpose) citation: polar research 2015, 34, 23225, http://dx.doi.org/10.3402/polar.v34.23225 http://www.polarresearch.net/index.php/polar/article/view/23225 http://dx.doi.org/10.3402/polar.v34.23225 postglacial marine and lacustrine sediments in lake linnevatnet , svalbard john inge svendsen, jon y . landvik, jan mangerud and gifford h. miller svendsen. j . i . , landvik, j . y . , mangerud, j . & miller, g. h . 1987: postglacial marine and lacustrine sediments in lake linnevatnet, svalbard. polar research 5 n.s., 281-283. john inge svendsen. jon y . landuik and jan mangerud, department of geology, sect. b , allkgt. 4 1 , n 5007 bergen. norway; gifford h . miller. university of colorado, instaar. campus box 450, boulder, co 80309, u . s . a . lake linnevatnet is situated near the mouth of isfjorden, on thc west coast of spitsbergen (fig. 1a). according to denton & hughes (1981) and mangerud et al. (1987) it lies within the late weichselian ice boundary. whereas according to boulton (1979) and troitsky et al. (1979) i t is outside that boundary. the purpose of this paper is to describe the stratigraphy of the lake sediments and discuss the timing of the glacial retreat. the lake floor and its sediment sequence was mapped with a kaytheon penetrating echosounding system (k'it-1000a) during the summer of 1984 (mangerud et al. 1985) and was subsequently cored from the winter ice in 1986. most of the cores have not yet been studied in detail, but a simplified stratigraphy of the lake sediments is presented here. the lake surface is located 12 m a.s.1. and the basin is nearly 40m deep. the main sediment supply is from a meltwater stream which enters the southern end of the lake. the physio graphy of the lake is described by bciiyum & kjensmo (1978). they also studied a 6 m long mackereth core from the deepest part of the lakc which penetrated into marine sediments of early holoccne age (boyurn & kjensmo 1980). the postglacial marine limit is between 65 and 78 m a.s.1. (sandahl 1986; san dahl et al. unpublished). and for the first 2.500 years after deglaciation the lake was a fjord. after emergcnce from the sea the lake was dammed up by a beach terrace across the valley, approximately 30 m a.s.1. (sandahl 1986). the outlet sub scquently eroded to the prcscnt level of 12 m a.s.1. stratigraphy the stratigraphy derived from the penetrating echosounding is consistent throughout the lake basin, with two distinct units above the acoustic basement (fig. 1b and 1c). the coring showed that the only major reflector that could be identified was the boundary between the upper lacustrine sediments and the early holocene marine sediments. the acoustic basement is distinct and it is interpreted as the surface of bedrock or possibly till. maximum thickness of the sequence in the central part of the lake is about 16 m. sediment cores were recovered with piston samplers at thc southern end of the lake (fig. 1b). this part of the lake, which is about 1&15 m deep, includes two sub-basins separated by a ridge. the eastern sub-basin lies outside thc delta front and rcceives sediments from the main river. the western basin is partly shielded from this source by the north-south trending ridge and receives almost all its sediments from a s m a l l nearby cirque with young end-moraines. studies of holocene glacier variations will be undertaken in this basin. the preliminary results presented here (fig. 1d) are based on a 12 m long core (no. 14) from a small well-defined bedrock depression in the eastern sub-basin (fig. 1b). this core is particularly relevant for dating the deglaciation because i t pen etrated to a resistant layer which is interpreted as bedrock or till. the marine sequence consists of a normally consolidated silty clay with some dropstones. different beds are distinguished by texture and colour. the variation in colour is primarily caused by the differing amounts of monosulphides present. in addition, there is variation in the frequency of molluscs and icedrop material throughout the sequence. the highest con centration of coarse grained material is found in the upper half of the sequence with a distinct maximum between 8.1 and 7.9 m. interbedded in the sequence are some 5 to locm thick well defined sorted sand layers. these layers also contain some clasts of silt and clay at the base. the sand was probably deposited from high-density turbidity currents from the steep slopes sur rounding the basin. in the upper part of the formation, flow structures, small-scale folds, faults. joints and mud clasts were observed. indicating synsedimentary slumping activity. according to a sea level curve constructed by sandahl(l986) the basin emerged about 9,500 years b.p., and at that time a continuous lacustrine sedimentation began. the boundary between the marine and lacustrine sediments is very pronounced, as the marine formation is nearly massive. whereas the lacustrine is distinctly laminated. in the lacustrine formation the thickness, frequency and texture of the individual laminae vary. the lower part of the lacustrine sequence is differcnt from the sediments above due to a higher content of carbonate matter (fig. id). this part is characterized by distinct black (monosulphidic) laminae which decrease in frequency upwards. the lamination is partly on a submillimeter scale, hut individual lamina may he more than 5 mm thick. most laminae arc normal graded with a lower light and upper dark zone. it is not clear whether the laminae were formed by individual meltwater plumes entering the lake, or whether they represent yearly varves. a preliminary foraminifera analysis has been undertaken by anne katrine lycke, university of bergen. the fauna is dominated by different elphidium species together with cos sidulina reniforme. the record is difficult to interpret, hut a sudden increase in the diversity of species at the base of the core indicates a rapid improvcment of the marine environment following the deglaciation. this is consistent with the lack of 282 j o h n inge suendsen et al. carbonate 10 20 30 40 50% 7 rganic :arbon i 2 3 4 9 f laminated silt and clay massive silty clay sand slumping structure lcedrop material bedrock or till i 30 fig. i . a: lake linnevatnet and its surroundings with a key map of svalbard. b: bathymetric map of the southern part of lake linnevatnet. the depths are given in metres. coring sites and the echo-sounding profile x-y shown on fig. 1c are indicated. c: an echo-sounding profile x-y across the southern end of the lake (fig. ib). d: description of core no. 14. postglacial marine and lacustrine sedimeits in lake linnkuatnet, svalbard 283 laminated glaciomarine sediments at the base of the core which may indicate a rapid retreat of the icefront. the variation in the frequency of molluscs and icedrop material might be a result of climatic changes, e.g. glacial activity during the younger dryas. a more detailed foraminifera analysis may help to clarify the cause of this variation. date of the glacial retreat two accelerator radiocarbon dates of molluscs, one from 50 cm and the other from 70 cm above the base of the core yielded 11,770 f 140 (ua-291, bafhyarca glacialis), and 11,490 * 150 (ua-290, nucula tenuis) years b.p., respectively. we assume that the sedimentation rate was rapid. thus these dates give a relatively precise age of the deglaciation and retreat of the valley glacier that occupied the basin during the late weichselian (mangerud et al. 1987). beyum, a . & kjensmo, 3. 1980: postglacial sediments in lake linnevatnet. western spitsbergen. arch. hydrobiol 88,232 249. boulton, g . 1979: glacial history of the spitsbergen archipelago and the problem of a barents shelf ice sheet. boreas 8. 31 57. denton, g. h . &hughes, t. j. 1981: the arctic ice sheet: an outrageous hypothesis. pp. 437467 in denton, g . h. & hughes, t. j. (eds.): the last great ice sheets. john wiley & sons, new york. mangerud, j . , landvik, i. y., salvigsen, 0. & miller, g. h. 1985: lake linnevatnet, svalbard, a possible 40,000 years continuous record of lacustrine and marine sedimentation. 14th arctic workshop. arctic land sea interactions. abstracts. bedfurd inrtitute of oceanography, dartmouth mangerud, j . , bolstad, m., elgersma, a , , helliksen, d., land vik, j. y., lycke, a. k., l@nne, i., salvigsen. 0.. sandahl, t. & sejrup, h. p. 1987: the late weichselian glacial maxi 1985, 82-85. mum in western svalbard. polar research 5n.s. (thisvolume). sandahl, t. 1986: kuartergeologiske undersgkeker i omrddet lewinodden kapp starostin linnkoatnet, ytre isfiorden, soalbard. unpublished thesis, univ. of bergen. troitsky. l . , punning, j.-m., hutt. g . & rajama, r. 1979: pleistocene glaciation chronology of spitsbergen. boreas 8, references beyurn, a . & kjensmo. j . 1978: physiography of lake linnc vatn, western spitsbergen. verh. internat. verein. limnol. 20. 609-614. 401-407. five short pollen diagrams of soils from jan mayen, norway: a testimony of a dynamic landscape w. 0. van der knaap van der knaap. w. 0. 1987: five short pollen diagrams of soils from jan mayen, norway: a testimony of a dynamic landscape. five soil cores varying in length from 30 to 42 cm and seven surface samples were analysed for pollen and spores. the soil layers of four cores were probably formed through redeposition of other eroded soils. only in the batvika core is the organic fraction of probable local origin, and here a chronology could be established. a total long-distance pollen influx of 1 4 2 2 . 5 grains/cm2/year was calculated. nearly 2,000 long-distance pollen grains were counted: the ratios of the dominant pollen types were calculated. around bitvika the past environment was relatively stable: only one major shift i n sedimentation environment is apparent from the diagram. in another diagram, expansion o f taraxucum species could be correlated with anthropogenic soil disturbance. the former presence of lycopodium alpinum and selaginella selaginoides on jan mayen is indicated by frequent spore finds; the latter species has not been found on the island before. two unknown spore types are discussed. w . 0. van der knaap, arctic centre, grote kruifstraat 2-1, 9712 ts groningen, the netherlands, or: laboratory of palaeobotany and palynology, heidelberglaan 2, 3584 cs utrecht, the netherlands; sep tember 1986 (revired may 1987). polar research 5 n . s . , 193-206. during the years 198cl1983, archeological, his torical, and biological studies were carried out on north-west spitsbergen, in the scope of the so called smeerenburg-project of the arctic centre, groningen, the netherlands. the aim of this multidisciplinary project was to investigate and reconstruct the living and working conditions of the 17th-century dutch whalers in spitsbergen. results are published in hacquebord (1984); the j a n mayen k v a l r o s s b u k t o u fig. 1. map of jan mayen indicating the coring localities palaeobotanical aspects are described in more detail in van der knaap (1985). another 17th century dutch whaling station of importance was situated on jan mayen, an isolated island in the arctic ocean between iceland, spitsbergen, greenland, and norway. the smeerenburg-pro ject has been succeeded by the jan mayen-project which functions on the same basis. the aim of the present palynological study was to reconstruct climatic phases during the last few centuries and to determine the influence of the 17th-century whalers on the natural arctic vegetation of jan mayen, as had been done successfully on spits bergen (van der knaap 1985). description of environment and sites the description is mainly based on van franeker (1983). jan mayen is an island of volcanic origin at 71"n, 8"30'w, and measures approximately 15 x 50 km. the glacier-covered, 2,200 m high volcano beerenberg is the highest mountain; the remaining half of the island consists of sandy and rocky plains, hills, and mountains up to approxi mately 600m. the climate is mid-arctic and strongly oceanic, and it is characterized by fre 194 w . 0. van der knaap quent and heavy fogs and storms. t h e soft, vol canic rocks are very sensitive to erosion; stone and mud slides. sand and dust storms are common. d u e to the high permeability of the bedrock, fresh water is rare after snowmelt in 'spring'. vegetation is scanty and consists mainly of mosses and lichens on the less unstable soils and rocks. vascular plants are sparse; 64 species are known (lid 1964; baagae & vestergaard 1974). peat bogs, fens, and marshes are com pletely lacking. during the 'fiifmarus ,glacialis expedition 11' jan-andries van franeker and kees camphuijsen collected twelve soil cores varying in length from 26 to so cm from five localities and seven surface samples; four cores and the surface samples were studied. one core collected by d r . louwrens hacquebord was studied. bkrvika core. collected 7-8-1983, 70"55'9"n. 8"44'0'w. alt. 15-20 m . sea distance c. 200 m . c. 1 km n of the borgsletta core. just under the outer wires of a mast. in a shallow. dry gully on a terrace below the debris slopes of trollslottet. the vegetation is relatively rich and consists of mosses, festuca rubra, l u a t l a arciiata, e q i t i setiirn arvense, salix herbacea, polygonurn vivi parum. a n d s o m e oxyria digyna. absent here are cochlearia officinalis and saxifraga species. borgslefra core. collected 7-8-1983. 70"s4'38"n, 8"44'40"w. alt. c. 25 m . sea distance c. 1 5 0 m . c. 1 k m s of the batvika core. hori zontal area poor in vegetation: mosses and lichens only partly covering the soil. some salix herbacea, luzula arcuata, and festuca rubra (veg.) are present. but few other species are found in the surroundings. among them saxifraga opposirifolia. hollendarhaicgen core. collected 24-6-1983. 70"58'0"n, 8"40'50"w. alt. c . 10 m. sea distance 3 0 0 m . c. 1 km se of the kvalrossbukta core. hollendarhaugen is a low hill with two burial mounds o n top. in legend connected with seven dutch whalers who died on jan mayen during the winter of 1633-34 (brander 1934). in 1931 a wooden cross was erected on the hill. t h e core was taken from a stony soil between the stones of a dry gully on the slope south of the hill. where some mosses and grass grow. sjiihollendarbukta core. collected in 1983 by d r . louwrens hacquebord. 70"55' c. 2 0 n , 8"54'w. alt. 15-20111. sea distance c. 0.5 km. in a dry gully on a green plateau above t h e sandy bay. species present at t h e t o p of t h e core (surface c. 2 dm2) are: salk herbacea, oxyria digyna, poa alpina vioipara, cerastiurn alpinurn (veg.), and carex lachenalii. kvalrossbukta core. collected 25-6-1983. 70"58'22"n, s"41'40w. alt. c. 15 m. seadistance c. 10 m. c . 1 km n w of the hollendarhaugen core. near the remains of huts of 17th-century dutch whalers, in rich vegetation at the base of a fulmar bird colony o n t h e rocks of the kvalrossen mountain. abundant vegetation of mosses, grass, cochlearia officinalis, and oxyria digyna. tar axacuni spp. and saxifraga cernua are frequent, s . caespitosa and other saxifraga species are occasionally found. sirrjacp saniples. nos. 1 4 were collected on 23 6-1983 near hollendarhaugen; see the description of the coring site. no. 1 was taken from a dense moss vegetation just south of the eastern burial mound. no. 2 was taken from a dense moss vegetation n e of t h e eastern burial mound. t h e sample consists of a sphagnum species. no. 3 was taken at the coring site. no. 4 is the packing material used for a core (not studied) at the site of n o . 1 . t h e sample consists of the moss raco mitriuni sp. and sand. surface samples nos. 5 and 6 were collected on 7-8-1983 around t h e bitvika and t h e borgsletta cores, respectively; see the description of the coring sites. no. 7 was collected on 7-8-1983 about halfway the sites of nos. 5 and 6. in borgdalen on a ridge in the valley. alt. c. 50 m . sea distance c. 0.5 km. t h e vegetation is very open and consists mainly of patches of moss, with some salix herbacea, saxifraga oppositifolia. liizula arcuata, and cerastiurn alpinurn in between. field sampling methods van franeker and camphuijsen collected the cores with a home-made gouge 5 cm in diameter and 50 cm long, and packed them in plastic half tubes. it was difficult t o obtain good cores in this way, as most soils appeared t o be somewhat incoherent. hacquebord d u g o u t t h e core with a spade and packed it in a flower-box of c. five short pollen diagrams of soils 195 riuularis; saxifraga stellaris type is renamed saxi fraga nivalis type and also includes s. tenuis and s . foliolosa. umbelliferae pollen was identified by punt (1984). two unknown spore types (‘spore p’ and ‘spore b’) were also counted. in the bitvika, borgsletta, and hollendarhaugen cores, separate samples were taken for the deter mination of specific weight and of loss-on ignition. the work was carried out in the labora tory of palaeobotany and palynology, utrecht. the netherlands. two radiocarbon dates were provided by prof. dr. w. g. mook, isotope physics laboratory, groningen, the netherlands. 15 x 20 x 60cm. in this way the layering of the soil is not disturbed and there is plenty of material for research. the surface samples consist of a small number of fresh moss plugs each, collected within 1 m2. the vegetation of coring and surface-sample sites was described in general terms, including plant names varying from family to species, and often a number of common flowering plants around the sites were collected separately and added to the surface samples for identification. these plants were removed before treating the samples. laboratory methods presentation of results dry weights of all samples used for pollen analysis and volumes of the samples of the sjuhol lendarbukta and the hollendarhaugen cores were measured. pollen and spore concentrations were determined by the addition of tablets containing 11,329 -t 349 spores of lycopodium clavatum (stockmarr 1971). vertical length and quantity of the samples vary somewhat between the cores. in the batvika core there are n o gaps between the samples. and dry weight is c. 1-1.5 g. in the borgsletta core the samples have a length of a half to two thirds of a cm, so there remain gaps between the samples, and dry weight is c. 0.5 1 g. in the hollendarhaugen core there are no gaps between the samples, and the volume is 2 4 cm3. in the sjuhollendarbukta core there are no gaps between the samples except between the upper two and the lower three; the two basal and the top sample have a length of 2cm, the remaining samples are 1 cm, and the volume is c. 1.5 cm3. in the kvalrossbukta core the samples have a length of nearly 1 cm and dry weight is c. 2-4 g. treatment followed in general the methods described by faegri & iversen (1975), including sieving over a 0.12 mesh screen and cold overnight treating with 30% hf. the surface samples were treated in the same way, but no lycopodium tablets were added. not more than one slide was counted for most of the samples. all pollen grains and spores of vascular plants and sphagnum were counted and identified. verbeek-reuvers (1977) was used for the identification of saxifragaceae pollen; two types have been renamed after species growing in the arctic and on jan mayen. saxi fraga granulata type is renamed saxifraga cae spitosa type and also includes s. cernua and s . the results are presented as concentration dia grams for all cores (figs. 3-7) and a percentage diagram for the surface samples (fig. 2 ) . pollen and spore types were grouped into two categories, as in earlier work (van der knaap 1985): local regional component, pollen and spores presumed to be derived from plants growing on jan mayen, and long-distance component, pollen and spores originating in areas outside jan mayen. the two unknown types ‘spore p’ and ‘spore b’ are plotted separately from the two components. zones were established in the diagrams for the ease of refer ence. the criterion for zonation was that the zones should be homogeneous in pollen content and differing from adjacent zones. at the far right side of the diagrams are shown the total cumulative long-distance values on 1 cm?. in the sjuhollendarbukta and hollendarhaugen dia grams these values could be calculated directly from the concentration values (number of grains in 1 cm3); in the other diagrams the concentration values (number of grains in 1 g dried sediment) first had to be converted into number of grains in 1 cm3 by means of the calculated and interpolated specific-weight values. the lithology of the cores is described at the far left side of the diagrams (figs. s 7 ) . unbroken horizontal lines indicate abrupt and clear tran sitions between soil layers. broken lines indicate gradual and/or indistinct transitions. the artefact in zone hollendarhaugen-3 at 9-11 cm is a thin piece of wood 2.5 x 1.5 x 0.2 cm. the layering i n the upper part (c. 8-13 cm) of this zone is some what irregular. 196 w. 0. van der knaap j a n m a y e n surface-sample d i a g r a m .?j no s a l i x h e r b a c e a o x y r l o n cruci f e r a e gra m i n e a e c o o ~ , n @ c a r y o p h y l l a c e o e p 0 s a x i f r a g a o p p o s i t i f o l l a -0u l s a x i f r a g a caespitosa t y p e 0 ~ = l 17 ranu ncul us g o 0 c y p e r a c e a e 0 0 d r y o p t e r i s t y p e -. s ph a g n um c o m p o s i t a e 1 1 g u l i f l o r a e cassiope y l o c a l r e g i o n a l c o m p o n e n t fig -7 furface-\amplr. pcrccntdge dldgram n o 1 2 3 l 5 6 7 p i n u s u r t i c a [i o ci a r t e m i s i a _ a l n u s c e r e o i i a -0 n o 0 c c h en o pad lac um be i i i f e r a e c a s t a n e a a n t h e m i s c a n n a b i s f r o x i n u s u l m u s 'lantago lanceolata l o n g d i s t a n c e c o m p o n e n t number of 289 8 3 l 700 3 8 8 g r a i n s c o u n t e d l65 5 2 3 1860 f i l i p e n d u l o p e r c e n t a g e s b a s e d an 1 5 % i 2 5 % t o t a l p o l l e n s u m a n a l y s i s j f n . v a n l e e u w e n i n the comparative summary diagram (fig. 9 ) , histograms of the dominant pollen types are given. pollen values are calculated as percentages of a total long-distance pollen sum. all samples of a pollen zone in the concentration diagrams (figs. 3-7) are added together in order to attain a sufficient number of long-distance pollen grains. consequently, each spectrum in the comparative summary diagram represents an entire zone of a concentration diagram. f o r the vertical axis of the comparative summary diagram are used the total cumulative long-distance values on 1 cm?. and n o t , as in the concentration diagrams. depth in cm. results surface samples in spite of the incomplete vegetation data of t h e surface sample sites. some interesting relation ships can b e noted. polygonum viuiparum seems to produce very little pollen on jan mayen, although the species is widespread (lid 1964). it grows at t h e site of sample no. 5 (bitvika core), but no pollen turned up in any of the surface samples or cores. equi setunr aruense, even more widespread on jan mayen (lid 1964), seems t o b e a low spore pro five short pollen diagrams of soils 197 c 0 ; e c 5 od e .* g 2 8 c m y 2 i “rn m 198 w . 0. van der knaup q b p &\. a t 0 0 h o l l e n d a r h a u g e n 3 p p i' 2 c -i / l o c a l r e g i o n a l c o r n fi g. 5 . h ol le nd ar ha ug en c on ce nt ra ti on d ia gr am . ' i 1 p o n e n t i ll'll z o n e 4 ,0 0 0 i;: 1 3 ,o m z o n e 2 3 c rp o n g d i s t a n c e c o m p o n e n t 200 w. 0. uan der knaap e e a e e e 00 c ... .d c 0 c m 2 + u p 0 -c i z 6 2 five short pollen diagrams of soils 201 fig. 7. kvalrossbukta concentration diagram. ducer; it also grows at the site of no. 5 , but spores are absent from all the surface samples and low in concentration in all diagrams. as surface samples nos. 3, 5 , and 6 are taken at coring sites, it is not surprising that these spec tra are similar to the upper spectra of the associ ated cores. a n exception is the low value of cruciferae pollen compared to the bitvika core; cochlearia oficinalis (cruciferae), however, is absent from the present-day vegetation of the site. it should be noted that oxyria is the dominant pollen type in the hollendarhaugen core, in sur face samples nos. 1-4 taken nearby, and in the nearby kvalrossbukta core, and that salk herba cea is the dominant pollen type in surface samples nos. 5-7 and in the nearby bitvika and borgsletta cores. lithology the soil stratigraphy is different in all thirteen collected cores. none of them is homogeneous throughout; they are built up of 2-8 (mean: 6) . . . . . . 174 . . . . . . . . . . . 9 6 3 3 . . . . . . . . 74 73 . . . . . . . . . . . . . . . 4 5 . . . . 3 3 . . . . . . 24 i zone 2 00 do zone 1 0 0 o n o l y s i s i f n v a n l c c u y c ~ layers differing in colour, proportions of organic material and sand, grain sizes of the sand, and type and degree of preservation of plant material. many transitions between soil layers are abrupt. such a stratigraphy is indicative of a strongly fluctuating sedimentation environment, as might be expected on this island with its harsh climate and soft rocks. while interpreting the diagrams, it is important to remember that the soil layers can differ in sedimentation rate, that part of the organic material (including pollen and spores) can be redeposited from eroded soil, and that there can be sedimentation gaps or erosion phases at all abrupt transitions between the layers. the bitvika core is a possible exception. the zone transition is the only discontinuity in both bioand lithostratigraphy; there are no litho logical indications of irregularities in the sedi mentation rate within the zones. landscape characteristics suggest that erosion takes place on the barren, stony hill slopes, and not on the densely moss-grown terrace where the core was taken. therefore, the organic component of the sediment is probably of local origin. 202 w . 0. van der knaup chronology undisturbed sediments without sedimentation gaps are needed for the determination of sedi mentation rates and of pollen influx values. only in zone bitvika-2 are these requirements likely to be fulfilled; here no lithological or biostrati graphical horizons are present and pollen is probably not reworked. the calibrated radio carbon date in this zone is a.d. 141s1630 (stuiver 1982; stuiver & pearson 1987); this implies a sedimentation rate of 3.5-5.7 cm/100 years and a total long-distance pollen influx of 14-22.5 grains/cm2/year. this corresponds very well with total long-distance influx rates in lakes in south greenland (fredskild 1973). if the long distance influx has been constant throughout, then the dating of the base of zone blvika-1 will be between a . d . 270 and 920, or even earlier if there is a hiatus at the zone border. the artefact in zone hollendarhaugen-3 at 9 11 cm must have been brought up together with the sand now forming the disturbed layer between c. 8 and 13 cm, during the erection of the wooden cross in 1931. the base of the overlying and apparently undisturbed layers is situated at c. 7 8 c m ; this results in a total long-distance pollen influx of 15-30 grains/cm’/year since 1931. this agrees with the influx values found in zone bitvika-2. the radiocarbon date in zone sjuhollendar bukta-5 is given in percentages of radioactivity instead of radiocarbon years, and is from this century. the distinct horizontal layering of the sediment may indicate that the stratigraphy is undisturbed. if this is the case, then the sediment has at least partly been redeposited by wind or water from different source areas. the accumulation values of total long-distance pollen, used as the vertical axis of fig. 8, probably do not provide a means of chronological cor relation between the diagrams. the requirement of an uninterrupted sedimentation of non redeposited material is in most cores probably not fulfilled. . i z d ! long-distance pollen a total of 1,918 long-distance pollen grains was counted in all cores and surface samples together. in table 1, percentages based on a total long distance pollen sum are listed for the cores and surface samples of the eight types of which more than ten grains were found. average percentages are listed in the last column. the 0.95% con fidence limits were calculated for all percentages by means of the nomograms in maher (1972); bold figures are values that differ significantly from the average value of the same type. an explanation of the deviations must remain very tentative. it could be that the winds carrying the long-distance pollen found in the surface samples were from more northern directions com pared to an average situation, and those in the sjuhollendarbukta core from more southern directions. this would explain the relatively high percentage values of pinus in the surface samples and the low values in the sjuhollendarbukta core. however, indications are totally absent in any of the diagrams of periods differing qualitatively in long-distance pollen. bdtvika: past environment it can be observed in the bitvika diagram that the general trends of the curves are similar. this ‘common trend’ has been presented as a separate curve in order to facilitate interpretation. the common-trend curve was calculated as follows: 1. the influence of the dominant pollen types s a l k herbacea, oxyria, and cruciferae is reduced by dividing concentrations by a number, fixed for each type in such a way that a mean concentration of 200 grains/g, similar to that of many other types, is reached; 2. the peak concentration of koenigia at 8cm. that does not follow the observed common trend, is omitted; 3. the total concentration values of all types are plotted at every level, resulting in a curve, defined here as the common-trend curve. the fluctuations of the common-trend values depend on fluctuations in either accumulation rates of the sediment, or pollen influx values (number of grains/cm*/year). the last is highly improbable for several reasons. the first reason is that the trends observed in the total long distance curve and in the curves of the local regional component are similar, as is shown graphically in fig. 8. the total long-distance values are plotted here against the ‘common trend values minus total long-distance values’, as the last are a constituent part of the first. only the top sample of zone bitvika-1 is far removed from a predicted linear relationship; the total long-distance value is about half the predicted value. it can hardly be assumed that the two 1501 i o o c 5 0 0 0 five short pollen diagrams of soils 203 b d t v i k o / / / / / / / u / i o m m o n t r e n d v a l u e s e x c l long-distance t o t a l 1000 2000 3000 4000 5000 fig. 8. bitvika core, correlation common trend/fotal long distance; explanation, see text. factors influencing pollen influx values, namely pollen production and dispersal, fluctuate along parallel lines for local-regional types and long distance types. redeposition of pollen from eroded organic soils, a possible cause for the observed common trends, has probably not taken place, as shown above. the final conclusion is that the direct cause of the observed common trend is fluctuation in the deposition rates of the total organic and inorganic sediment. in the common-trend curve a sharp decline can be observed at the zone transition, and minor fluctuations within each zone. the sharp decline indicates a major shift in the deposition environ ment, resulting in lower concentration values of pollen and spores. a possible event could be a nearby landslide, resulting in an enlarged source area of the sand to be deposited. at the top of zone bbtvika-1 the common-trend curve reaches a maximum, indicating an event possibly related to an inferred major environmental shift. the 204 w . 0. van der knaup c o m p f i g . 9, comparative u r n m a r ? d i a g r a m . the curnulatire long-distance pollen values used as t h c verlical axis (extrcrne left) probably do not provide a reldti\c tirnc scale: explanation. w e tcxi minor huctuations in the common-trend curve are possibly connected with climatic factors influ encing sand deposition rates, such as wind vel ocities and wind directions. t h e data. however, d o not allow a more detailed climatic inter pretation. past vegetution the best base for interpretation in terms of past vegetation are pollen influx values (number of grains/cm'/year ). these values cannot be cal culated from the available data. instead. per centage values based on a total long-distance pollen sum are used (fig. 9); such values a r e only dependent on variations in total long-distance pollen influx values, and are independent of accumulation rates of the studied sediments, and of each other. only major differences between pollen zones a r e considered to be significant. for two reasons; 1. statistically speaking, the per centages have low reliability because most values exceed 100% and because the pollen sum is often rather low; 2. t h e r e has probably been some variation i n the total long-distance pollen influx during t h e last millennia, as has been the case, for example, in greenland (fredskild 1984), and on spitsbergen and bjornciya (hyvarinen 1972). with the exception of the two identical pollen zones bstvika-1 and -2, all zones differ strongly from each other in percentage values of o n e or more pollen types. this must b e d u e to differences in past vegetation. interpretation of the data in terms of past vegetation composition is in dependent of the degree t o which the sediments were redeposited from eroded soils, provided that pollen and spores were not sorted during re deposition. any possible redeposition would cause uncertainty in determining t h e age and location of former vegetation. so t h e data cannot be interpreted in terms of vegetation succession, sediment formation, o r changes in environmental factors, because a chronological base is lacking and erosion/sedimentation patterns have not been studied in detail. only a few features of t h e diagrams will b e discussed here. dandelions (tararacurn spp.) a r e t h e only re presentatives of t h e compositae liguliflorae o n jan mayen. long-distance transport of this pollen type can only be exceptional; most grains found in the cores must therefore be derived from dan delions from the island. brander (1934) tells us that the dandelions o n j a n mayen were probably introduced by the 17th-century dutch whalers. five short pollen diagrams of soils 205 the regular presence of pollen of compositae liguliflorae in both zones of the bitvika diagram indicates, however, that dandelions grew on the island long before the discovery of jan mayen. dandelions are generally favoured by disturbance and manuring of the soil; the explosive expansion seen in zone hollendarhaugen-4 therefore prob ably occurred at the time of the erection of the wooden cross in 1931. the expansion of dan delions seen in zone sjuhollendarbukta-5 cannot directly be correlated with historical events. the radiocarbon date in this zone indicates that the whole sequence from this level to the top oi the core might be recent. an alternative explanatiofi is that environmental pollution associated with the whaling activities of the 17th-century dutch whalers might have caused an explosive expansion and flowering of the native jan mayen dandelions; such an observation could have been the basis of brander’s remark. sterile plants of lycopodiurn alpinurn were found only once on jan mayen ( b a a g ~ e & vester gaard 1974). spores of lycopodium alpinurn type were found in 12 samples in nearly all cores. long-distance transport can only be responsible for one or very few spores; this means that fertile plants were (or are) present on the island. so far, selaginella selaginoides has not been found on jan mayen. the frequent spore finds, especially i n the b5tvika core, indicate that the species has grown on the island for centuries, as long-distance transport can only be responsible for very few grains. the plant, which resembles and frequently grows between mosses, is easily overlooked i n the field. two unknown spore types, called here ‘spore p’ and ‘spore b’, were counted. for details of spore p, see photographs fig. 10. the spores are thin-walled and about 30mp. one side of the grain has an indistinct trilete mark, the other side has a fingerprint-like structure somewhat remi niscent of polemonium pollen grains. the grains are often folded, but otherwise fairly constant in characteristics. the author also found two grains in the spitsbergen core %re salatberget-c’ at 13.5cm (van der knaap 1985). the frequent polemonium pollen finds of zelikson (1971) in a spitsbergen peat bog could be a misidentification of this spore p. spore b was found only with a few grains. in an unpublished study of a core from angmagssalik (greenland) many were found by the author; this type will be discussed and described in more detail fig. 10. spore p: c. 1 2 5 0 ~ in a later publication. spore b is rather variable. some forms are nearly identical to botrychiurn spores, but in most grains the surface structure and the trilete mark are less distinct. general conclusion the cores clearly reflect a very dynamic environ ment. erosion and sedimentation are the domi nant factors that determine the soil stratigraphy. it is difficult to establish a chronology. this could probably be done more easily when studying longer cores (up to some m) from favourable sites. it will be possible then to study vegetation succession; i t is seen in the present study that soil layers differ generally in pollen and spore assemblages, and these can be translated to some degree in past vegetation types. minor climatic fluctuations are in the sediments apparently obscured or not reflected. it is doubtful whether sediments can be found on jan mayen in which climatic fluctuations of the last few centuries to millennia can be studied successfully; peat bogs and suitable lake sediments seem to be absent. acknowledgemen@. i am grateful lo dr. bent fredskild and dr. c. r. janssen for their comments on the manuscript, and 206 w . 0. van der knaap to henry f. lamb for correction of the english text. i thank jacqueline f . n. van leeuwen for counting pollen. paul war tena prepared the drawings. the field work was financially supported by the aretic centre, groningen, the netherlands. references baagoe. j . & vestergaard. k. 1974: an annotated list of the vascular plants collected by the danish jan mayen expedition 1972. nor. polarinsr. arbok 1972. 55-61. brander, j. 1934: het ciland jan mayen en de overwintering aldaar van 163s1634. hisrorrrch genoorschap 'oud wesr friedorid'. 1-104. i map franekcr. j . a . van 1983: ecn verkenning van jan maven. een rapport op verzoek van het arctisch centrum. r u groningen. insritrirrr uoor taxommische zoologic. amster dam. 1-27. fredskild. b. 1973: studies in the vegctational history of green land. pdtaeohotanicat investigations o f some holocenc lake and bog deposits. meddeklser om grmland 1 9 x ( i ) . 1-247. 21 platea. fredskild. b. 1984: holocene palaeo-winds and climatic changes in west greenland as indicated by long-distance transported and local pollen in lake sediments. pp. 16s171 in morner, n.-a. & karl& w. (eds.): climaric changes on a yearly fo millennial basis fzgri. k & iversen. j . 1975: tenbook ofpollen analvsis. 3rd edition. munksgaard. copenhagen. 295 pp. hacquehord. l . 1984: the histor! of early dutch whaling: a study from the ecological angle pp 1 3 i l 4 8 i n s'jacoh. h . k., snoeijing, k. & vaughan, r. (eds.): arctic whaling. proceedings of the international symposium: arctic whaling, febnrory 1983. university of groningen. hyvarinen. h . 1972: pollen-analytic evidence for flandrian climatic change in svalbard. acro uniu. ouluensir, a3, geol ogica, 225237. lid, j . 1964: the flora of jan mayen. nor. polarinst. skrifrer 130, 1-107 maher. l. j . jr. 1972: nomograms for computing 0.95 con fidence limits of pollen data. rev. palaeobot. palynol. 13, 8 5 9 3 . punt. w. 1984: the northwest european pollcn flora, 37. umhclliferae. r e v . palaeobot. palynol. 4 2 , 155-364. stockmarr. j . 1971: tablets with spores used i n absolute pollen analysis. pollen and spores 13(4). 615-621. stuiver. m. 1982: a high-precision calibration of the a d radio carbon time scale. radiocarbon 24(2). 1-26. stuiver, m. & pearson. g . w . 1987: high-precision calibration of the radiocarbon time scale, a d 195s500 bc. radio carbon 28(2b) ~ 805838. van der knaap. w. 0.1985: human influcnce o n natural arctic vegetation in the seventeenth century and climatic change sincc a . d . 1600 in north-west spitsbergen: a palaeohotanical study. arctic and alpine research 17(j). 371-387. verheck-reuvers. a . a . m. l. 1977: thc northwest europcan pollen flora. 9. saxifragaceae. reu. palaeobor. palynol. 24: n e p f . 31-58. zrlikson. a . m . 1971: palynological investigation of a holocene peat deposit from spitsbergen. pp. 190-212 in neustadt, m. 1 . (ed.): holocene palwiologv for the 3rd lnternationul palynological conference (novosibirsk. u s s r , 1971). moscow (in russian). por_017.fm polar research 26 2007 175 – 180 © 2007 the author 175 r e s e a r c h n o t e national and institutional productivity and collaboration in antarctic science: an analysis of 25 years of journal publications (1980–2004) prabir g. dastidar ministry of earth sciences, block no. 9 & 12, cgo complex, lodi road, new delhi 110003, india abstract journal publications on antarctic science were analysed for a period of 25 years (1980–2004) through a set of scientometrics and network analysis techniques. the study is based on 10 942 records (research articles, review articles, letters, etc.) with the word fragment “antarc*” in the title published in 961 international, peer-reviewed journals and retrieved from thomson scientific’s science citation index database. during the period under investigation, productivity increased threefold and there was a 13-fold increase in journal publications co-written by authors from different countries. the five nations with the highest output were the usa (with 26.7% of the total output), the uk (13.8%), australia (9.7%), germany (8.8%) and italy (6.0%). the top five institutions in terms of journal publications were the british antarctic survey (972 publications), the alfred wegener institute of polar and marine research, germany (475), the australian antarctic division (312), the university of tasmania, australia (305), and the national aeronautics and space administration, usa (293). keywords antarctic science; journal articles; knowledge mapping; network analysis; science citation index; scientometrics. antarctica is the fifth largest continent. this coldest, windiest and highest continent is covered with an ice sheet more than 2-km thick, on average. having remained comparatively undisturbed and unpolluted for millions of years, the antarctic environment is a treasure trove of information about the earth’s past. the indian, atlantic and pacific oceans meet around antarctica, and the mixing process of cold and warm waters contribute to a special regime with unique physical, chemical and biological characteristics. these waters constitute one of the world’s richest biological provinces. for all these reasons, antarctica provides unique opportunities for scientific research in diverse fields. the antarctic treaty system— one of the world’s most successful international agreements—ensures that antarctica remains a natural reserve for science. there are 26 countries with seasonal or yearround stations in antarctica (table 1). this paper analyses a data set of journal publications for the period 1980–2004. an attempt has been made to identify the major players in antarctic science by identifying the nations and institutions that produced the greatest number of journal publications about antarctica. as conducting scientific research is central to the antarctic treaty system, an analysis of scientific output— measured here in terms of journal publications—in part reflects the functioning of this set of international agreements. similar analyses have been previously undertaken for journal publications in ocean science and technology (dastidar 2004; dastidar & ramachandran 2005), along with an earlier effort for antarctic science (dastidar & persson 2005). materials and methods the data for this study were drawn from thomson scientific’s science citation index, a database available on a series of annual cd-roms. the science citation index covers about 3700 of the world’s interntional, peerreviewed scientific and technical journals, and includes publication details for research articles, review articles, news items, book reviews, letters, communications, editorial material and so forth (see http://scientific.thomson. correspondence prabir g. dastidar, ministry of earth sciences, block no. 9 & 12, cgo complex, lodi road, new delhi 110003, india. e-mail: prabirgd11@rediffmail.com doi:10.1111/j.1751-8369.2007.00017.x http://scientific.thomson 176 polar research 26 2007 175 – 180 © 2007 the author national and institutional productivity and collaboration in antarctic science p.g. dastidar com/products/sci/ and http://thomsonscientific.com/ free/essays/selectionofmaterial/journalselection/). the database on the cd-rom for each year from 1980 to 2004 was searched for publications with “antarc*” in the title. this yielded 10 942 records, which formed the basis of the present analysis. to assess publication output for individual countries, each publication was given a value of 1. in the case of a multinational publication—a publication co-written by authors with addresses in two or more different countries—each contributing country was given a fraction value where the sum of fractions equalled 1. for example, in the case of a publication written by one author with a us address and one with an address in the uk, the usa and the uk would each receive a value of 0.5. these fractional values were summed to asssess the productivity of individual countries. it should be emphasized that this method of calculation makes no attempt to assess the actual relative contributions of the co-authors (neither, by extension, the nations they represent) by, for example, weighted scores. rather, each co-author of an article was assigned an equal fraction. it is a widespread practice to place the co-author who has contributed disproportionately to the the work of preparing a scientific article first on the author byline (yank & rennie 1999). however, other conventions may be applied and these vary across the international scientific community. among teams of scientists who frequently publish together, the co-authors may take turns being named as lead authors (o’connor & woodford 1978). in some scientific circles it may be customary to name heads of departments, laboratories or research groups as first authors (o’connor & woodford 1978). some journals have clear policies about how to determine the order of authors; most do not and there is apparently no clear consensus about the meaning of the order of authors among journal editors (yank & rennie 1999). for the purposes of the analysis, publications authored by writers in the federal republic of germany and the german democratic republic were merged under “germany”, whereas publications from writers with addresses in the ussr and russia were combined under “russia”. the country and names of institutions associated with the publications were isolated separately and rank ordered (persson 2004). the most productive units were chosen to form co-occurrence matrices to which a multidimensional scaling algorithm (a systat subroutine) was applied to produce the network maps. the relative size of the circles in these diagrams indicates the relative productivity of each entity, and the lines between the circles indicate the presence of collaboration links, whereas the line thickness indicates the strength of the interconnections (dastidar 2004; dastidar & persson 2005; dastidar & ramachandran 2005). an important limitation of this study is that the data were limited to the journals in thomson scientific’s science citation index. alhough non-english publications are included in the database, thomson scientific’s selection criteria make it easier for english-language publications to be included for coverage (see http:// thomsonscientific.com/free/essays/selectionofmaterial/ journalselection/). in addition, journal publications that concerned antarctica but which did not have “antarc*” in their titles were not included in this study. results during the study period the output of journal publications with “antarc*” in the title increased threefold, rising from 165 in 1980 to 552 in 2004 (fig. 1). output peaked in 2002, with 729 publications. over 80 nations were represented among the authorship of the publications being analysed (table 2). the output is highly skewed, with two countries—usa and table 1 number of stations in antarctica and manpower deployment contributed by the 28 consultative parties to the antarctic treaty system (www.comnap.aq/facilities). country no. of stations (year when first station was established) manpower (annual peak) argentina 6 (1904) 417 australia 3 (1954) 213 belgium — — brazil 1 (1984) 40 bulgaria 1(1988) 15 chile 5 (1948) 224 ecuador 2 (1990) 88 finland 1(1989) 20 france 4 (1956) (one jointly with italy) 145 germany 2 (1981) 78 india 1 (1989) 65 italy 5 (1986) (one jointly with france) 135 japan 2 (1957) 150 the netherlands 0 — new zealand 1 (1957) 85 norway 2 (1985) 44 china 2 (1985) 70 peru 1 (1989) 28 poland 1 (1977) 40 russia 7 (1956) 429 south africa 1 (1962) 80 south korea 1 (1988) 60 spain 2 (1989) 28 sweden 1 (1989) 20 uk 5 (1947) 205 ukraine 1 (1996) 24 uruguay 1 (1984) 60 usa 3 (1955) 1250 —, data not available. http://thomsonscientific.com/ http:// p.g. dastidar national and institutional productivity and collaboration in antarctic science polar research 26 2007 175 – 180 © 2007 the author 177 uk—each contributing shares larger than 10%, 16 countries each contributing shares between 1 and 10%, and all the remaining countries contributing shares of less than 1% each. the share for the usa was 26.7%, almost double that of the uk, which was the next most productive country, with 13.8%. the five most productive countries (usa, uk, australia, germany and italy) together contributed 65% of the total output. table 2 country-by-country output of journal publications with “antarc*” in the title, based on the annual cd-roms of the science citation index, 1980– 2004 ( n + 10 942). each publication was given a value of 1. in the case of a multinational article, each contributing country was given a fractional value where the sum of fractions equalled 1. these fractional values were summed to asssess the productivity of individual countries. consultative parties to the antarctic treaty system are indicated. (ecuador, also a consultative party to the treaty, is not included in the table because of its very low journal publication output.) data on per capita gross domestic expenditures on research and development are from the unesco institute for statistics (http://www.uis.unesco.org/ev.php?id = 5182 = 201&id2 = do_topic). country output % of world total per capita gross domestic expenditure on research and development, in purchasing power parity usd (year of data in parentheses) 1 usa a 2886.90 26.7 954 (2002) 2 uk a 1491.83 13.8 490.6 (2002) 3 australia a 1051.85 9.7 404.5 (2000) 4 germany a 948.87 8.8 686 (2002) 5 italy a 653.21 6.0 288.7 (2001) 6 france a 526.08 4.9 611.2 (2002) 7 japan a 492.22 4.5 836.6 (2002) 8 new zealand a 430.22 4.0 246.1 (2001) 9 russia a 305.86 2.8 102.2 (2002) 10 spain a 241.37 2.2 222.4 (2002) 11 south africa a 232.99 2.2 68.7 (2002) 12 argentina a 188.37 1.7 44 (2002) 13 the netherlands a 152.82 1.4 536.6 (2001) 14 india a 126.29 1.2 20.5 (2000) 15 belgium a 117.06 1.1 614.7 (2002) 16 canada 109.65 1.0 588.4 (2002) 17 sweden a 107.30 1.0 1082.5 (2001) 18 poland a 107 1.0 62.7 (2002) 19 china a 90.74 0.8 — 20 norway a 88.73 0.8 612.2 (2002) 21 chile a 63.16 0.6 51.9 (2001) 22 brazil a 58.49 0.5 76.9 (2000) 23 switzerland 50.78 0.5 740.4 (2000) 24 denmark 45.97 0.4 777.6 (2002) 25 south korea a 44.53 0.4 492.3 (2002) 26 austria 37.84 0.3 645.2 (2002) 27 finland a 35.99 0.3 905.2 (2002) 28 czech republic 13.99 0.1 — 29 bulgaria a 10.5 0.1 34.9 (2002) 30 hungary 9.16 0.1 135.3 (2002) 31 greece 9.08 0.1 115.8 (2001) 32 ukraine a 9 0.1 57.6 (2002) 33 ireland 8.91 0.1 369.2 (2001) 34 taiwan 8.5 0.1 — 35 israel 7.91 0.1 997.2 (2002) 36 mexico 6.16 0.1 38.3 (2002) 37 turkey 4.5 0.0 42.6 (2002) 38 bermuda 4.33 0.0 27.4 (1997) 39 iceland 3.90 0.0 925.7 (2002) 40 jamaica 3.33 0.0 3.0 (2002) 41 ukssr 3 — — a consultative parties. —, data not available. 42 pakistan 2.5 0.0 5.2 (2002) 43 estonia 2.25 0.0 98.9 (2002) 44 philippines 2 0.0 45 romania 2 0.0 24.9 (2002) 46 singapore 2 0.0 525.7 (2002) 47 antarctica 1.83 0.0 — 48 monaco 1.83 0.0 — 49 reunion 1.5 0.0 — 50 ciskei 1 0.0 — 51 colombia 1 0.0 10.5 (2001) 52 indonesia 1 0.0 — 53 ivory coast 1 0.0 — 54 kenya 1 0.0 — 55 papua new guinea 1 0.0 — 56 peru a 1 0.0 5.2 (2002) 57 portugal 1 0.0 170.2 (2002) 58 saudi arabia 1 0.0 — 59 vanuatu 1 0.0 — 60 zimbabwe 1 0.0 — 61 bolivia 0.5 0.0 6.9 (2002) 62 belarus 0.5 0.0 35.1 (2002) 63 comoros 0.5 0.0 — 64 costa rica 0.5 0.0 34.5 (2000) 65 latvia 0.5 0.0 42.8 (2002) 66 luxembourg 0.5 0.0 961.1 (2000) 67 morocco 0.5 0.0 — 68 namibia 0.5 0.0 — 69 new caledonia 0.5 0.0 — 70 niger 0.5 0.0 — 71 nigeria 0.5 0.0 — 72 qatar 0.5 0.0 — 73 slovenia 0.5 0.0 286.2 (2002) 74 sri lanka 0.5 0.0 5.1 (1996) 75 uruguay a 0.5 0.0 20.6 (2002) 76 venda 0.5 0.0 — 77 vietnam 0.5 0.0 — 78 yugoslavia 0.5 0.0 — 79 fiji 0.33 0.0 — 80 french polynesia 0.33 0.0 — 81 french guiana 0.33 0.0 — 82 venezuela 0.2 0.0 20.7 (2002) country output % of world total per capita gross domestic expenditure on research and development, in purchasing power parity usd (year of data in parentheses) a consultative parties. —, data not available. http://www.uis.unesco.org/ev.php?id 178 polar research 26 2007 175 – 180 © 2007 the author national and institutional productivity and collaboration in antarctic science p.g. dastidar as shown in fig. 1, the number and proportion of publications co-written by contributors from different countries increased over the period being examined. there were 15 multinational publications in 1980, which represented 9.09% of the total for that year. by 2004 there were 190 multinational publications, which constituted 34.42% of the total for that year. figure 2 gives an indication of the collaborative ties between countries, with the countries with writers who most frequently coauthor publications lumped together in the middle of the diagram. american authors most frequently contribute to multinational journal publications, followed by the uk, australia and germany. about 2837 organizations contributed to journal publications with “antarc*” in the title during the period studied. the 75 most productive institutions are presented in table 3. the british antarctic survey topped the list, having contributed to 972 publications. in second place was the alfred wegener institute for polar and marine research, with 475 publications. the remaining institutions among the top five were the australian antarctic division (312 publications), the university of tasmania, australia (305 publications), and the national aeronautics and space administration, usa (294 publications). the country with the most institutions appearing in the top 75 was the usa, with 26 institutions. australia had fig. 2 collaboration network of the top 13 countries in terms of the output of multinational journal publications with “antarc*” in the title, based on the annual cd-roms of the science citation index, 1980–2004 ( n = 82). line thickness and proximity of the circles indicates collaboration intensity between the countries. fig. 1 overall number of journal publications with “antarc*” in the title, and the number of these publications co-authored by writers from different countries, based on the annual cdroms of the science citation index, 1980–2004. the scale on the left-hand side of the figure indicates the overall number of publications and the scale on the right-hand side indicates the number of multinational publications. p.g. dastidar national and institutional productivity and collaboration in antarctic science polar research 26 2007 175 – 180 © 2007 the author 179 10 institutions among the top 74, new zealand had seven, and argentina and germany each had four. data for the ten most productive organizations were used to produce the network map presented in fig. 3. the diagram indicates frequent co-authorship between the british antarctic survey and the alfred wegener institute for polar and marine research. discussion scientific journal publications about antarctica in the period 1980–2004 were dominated by the nations with a strong interest in the continent. nineteen of the 20 countries producing the most publications are consultative parties to the antarctic treaty, and the top 20 countries included all 11 original signatories of the treaty (table 2). setting aside canada and the 11 original signatory nations, the remaining eight countries in the top 20 gained consultative status by having conducted substantial research activity there, as provided by article 9 of the treaty (http://www.ats.aq/). productivity in science is investment dependent, as is shown by the strength of the contribution to journal publications about antarctica in 1980–2004 by the usa. table 3 rank list of the 74 most productive institutes in terms of journal publications with “antarc*” in the title, based on the annual cd-roms of the science citation index, 1980–2004. ranking institution no. articles 1 british antarctic survey, uk 972 2 alfred wegener inst. for polar & marine res., germany 475 3 australian antarctic div., australia 312 4 university of tasmania, australia 305 5 nasa, usa 293 6 ohio state university, usa 244 7 university of california, san diego, usa 220 8 nerc, uk 216 9 cnr, italy 214 10 cnrs, france 205 11 national institute of polar research, japan 196 12 university of colorado, usa 163 13 csiro, australia 146 14 russian academy of sciences, russia 148 15 noaa, usa 137 16 caltech, usa 135 17 university of washington, usa 127 18 csic, spain 124 19 university of melbourne, australia 123 20 columbia university, usa 103 21 university of wisconsin, usa 102 22 university of maine, usa 101 23 university of genoa, italy 100 24 antarctic crc, australia 98 25 argentinean antarctic institute, argentina 95 26 university of tokyo, japan 94 27 university of canterbury, new zealand 94 28 us geological survey, usa 92 29 university of kiel, germany 89 30 university of alabama, usa 88 31 university of otago, new zealand 88 32 university of buenos aires, argentina 85 33 australian national university, australia 84 34 christian albrechts university of kiel, germany 83 35 dsir, new zealand 82 36 hokkaido university, japan 82 37 university of auckland, new zealand 81 38 university of utrecht, the netherlands 76 39 university of cape town, south africa 75 40 texas a&m university, usa 72 41 university of cambridge, uk 72 42 university of california, santa barbara, usa 71 43 university of illinois, usa 71 44 university of california, santa cruz, usa 71 45 lab glaciol & geophys environm, france 70 46 university of texas, usa 69 47 arctic & antarctic research institute, russia 69 48 macquarie university, australia 68 49 woods hole oceanographic institution, usa 67 50 university of paris, france 67 51 polish academy of sciences, poland 66 52 university of siena, italy 65 53 university of alaska, usa 64 54 university of bremen, germany 62 55 nat inst water and atmospher res, new zealand 60 56 university of wyoming, usa 60 57 university of copenhagen, denmark 60 58 university of pretoria, south africa 60 59 consejo nacl invest cient & tecn, argentina 60 60 university of hawaii, usa 59 61 chinese academy of sciences, china 58 62 oregon state university, usa 58 63 monash university, australia 56 64 university of california, usa (no specific campus stated) 54 65 university of bern, switzerland 54 66 university of california, los angeles, usa 53 67 university of waikato, new zealand 53 68 department of science, australia 52 69 university of liege, belgium 52 70 montana state university, usa 52 71 victoria university of wellington, new zealand 52 72 university of new south wales, australia 49 73 national center for atmospheric research, usa 48 74 university of bristol, uk 47 ranking institution no. articles http://www.ats.aq/ 180 polar research 26 2007 175 – 180 © 2007 the author national and institutional productivity and collaboration in antarctic science p.g. dastidar the usa alone contributed more than one quarter of all publications during the period, and, of the most productive individual organizations, one of three institutions in the list was american. the usa deploys the greatest manpower to the continent and maintains the largest research complex there. the usa has one of the highest per capita gross domestic expenditures on research and development, which is almost double that of the uk (table 2). as was also seen in the case of journal publications in ocean science and engineering (dastidar 2004), the most productive countries have higher per capita gross domestic expenditures on research and development. international collaboration is an important element in the antarctic treaty, which was originally signed in 1959 (http://www.ats.aq/uploaded/treaty_original.pdf). to promote international cooperation, article 3 of the treaty calls for the exchange of personnel and scientific results between the parties to the treaty. the 16th antarctic treaty consultative meeting declared 1991–2000 the decade of international antarctic scientific cooperation (cohen 2002). this study has shown a marked increase in one indicator of international scientific cooperation in antarctica: publications authored by writers from different countries. an important subject beyond the scope of this brief paper is the research topics of the journal publications relating to antarctica during the period in question. it would be extremely interesting to identify antarctic research trends in this way, and it is hoped that this will be the subject of further analysis. acknowledgements the author expresses his gratitude to prof. olle persson, dept of sociology, umeå university, sweden, for his guidance and constructive suggestions. the author is thankful to dr josé retamales, director of the chilean antarctic institute and chairman of the council of managers of national antarctic programs, for his suggestions and for showing keen interest in the work. the author is also thankful to dr b.s. aggarwal for editing an earlier version of the manuscript. references cohen h.k. (ed.) 2002. handbook of the antarctic treaty system . 9th edn. washington dc: us department of state. dastidar p.g. 2004. ocean science & technology research across the countries: a global scenario. scientometrics 59 , 15– 27. dastidar p.g. & persson o. 2005. mapping the global structure of antarctic research vis-à-vis antarctic treaty system. current science 89 , 11552–11554. dastidar p.g. & ramachandran s. 2005. engineering research in ocean sector: an international profile. scientometrics 65 , 199–213. o’connor m. & woodford f. p. 1978. writing scientific papers in english . london: pitman medical. persson o. 2004. bibexcel. downloaded from the internet at http://www.umu.se/inforsk/bibexcel on 27 february 2007. yank v. & rennie d. 1999. disclosure of researcher contributions: a study of original research articles in the lancet . annals of internal medicine 130 , 661–670. fig. 3 collaboration network among the ten most productive organizations in terms of the output of multinational journal publications with “antarc*” in the title, based on the annual cdroms of the science citation index, 1980–2004 ( n = 2726). line thickness and proximity of the circles indicates collaboration intensity between the institutions. http://www.ats.aq/uploaded/treaty_original.pdf http://www.umu.se/inforsk/bibexcel an enigmatic fossil penguin from the eocene of antarctica research note an enigmatic fossil penguin from the eocene of antarctica piotr jadwiszczaka and thomas mörsb ainstitute of biology, university of bialystok, bialystok, poland; bdepartment of palaeobiology, swedish museum of natural history, stockholm, sweden abstract tarsometatarsi are key skeletal elements in penguin palaeontology. they constitute, among others, type specimens of all 10 widely accepted species of fossil penguins from the eocene la meseta formation on seymour island (graham land, antarctic peninsula). here, we report on a recently collected large-sized tarsometatarsus from this formation that represents a new morphotype. we are convinced that the morphotype corresponds to a new species, but the material is too scarce for a taxonomic act. undoubtedly, the bone discussed here is a valuable addition to our knowledge on diversity of early penguins. keywords antarctic peninsula; la meseta formation; paleogene; sphenisciformes; tarsometatarsus; new morphotype eocene (56–34 mya) penguins (aves, sphenisciformes) have a remarkably extensive fossil record, especially in contrast to their earlier relatives known from the paleocene (66–56 mya) (jadwiszczak 2009). at present, various scientific institutions house thousands of eocene penguin bones, collected within several localities scattered throughout the southern hemisphere. most of these specimens, albeit very rarely in the form of articulated partial skeletons (e.g., acosta hospitaleche & reguero 2010), were recovered from the eocene la meseta formation on seymour island, antarctic peninsula (fig. 1; myrcha et al. 2002; jadwiszczak 2009; jadwiszczak & mörs 2011; reguero et al. 2013). holotypes of all 10 undisputed species assigned to six genera of early penguins from that formation are tarsometatarsi (myrcha et al. 2002; reguero et al. 2013; chávez hoffmeister 2014). importantly, a number of previous studies, also including those focused on tarsometatarsi (e.g., jadwiszczak 2008), have already demonstrated that the list of actual species (possibly also genera) is not exhaustive. herein, we report on a penguin tarsometatarsus that expands on the existing knowledge of the eocene penguin diversity. material and methods the bone considered here was collected in 2012 by tm in the upper part of the la meseta formation on seymour island (james ross basin, northern antarctic peninsula). it was found in the unit telm7 (or submeseta allomember; see marenssi 2006), traditionally regarded as late eocene in age, (e.g., marenssi 2006), within the swedish locality nrm 5 (64°14.490′s, 56°37.215ʹw) (fig. 1). this locality corresponds to the submeseta ii allomember or level 38 of montes et al. (2013) that they interpreted as late middle eocene (bartonian) in age. according to some recent sources (e.g., buono et al. 2016; kriwet et al. 2016), level 38 is of late eocene (priabonian) age. the fossil bone was found in situ while surface collecting. the site is a small, isolated plateau and it can be confidently excluded that the material has been transported by solifluction down from higher levels. the specimen derives from a fossiliferous horizon (fig. 1) that is very rich in vertebrate remains, especially penguins and teleosts, and has also produced a few chondrichthyan teeth (e.g., kriwet et al. 2016). the fossil specimen is housed in the collections of the swedish museum of natural history (naturhistoriska riksmuseet), stockholm, sweden (nrm-pz). the specimen was mechanically cleansed of remnants of the matrix material by pj in 2016. the graphical reconstruction of the medial margin (fig. 2d), following the preparation of the fossil, was based on the shape of its preserved parts, especially of the position of its maximum concavity. relevant tarsometatarsi of eocene antarctic penguins from rich collections held by the authors’ institutions — the university of bialystok, poland (ib/p/b) and the swedish museum of natural history, stockholm — also helped to (virtually) recreate the margin. data for present-day aptenodytes penguins (table 1) are based on specimens from the natural history museum at tring (uk), studied by pj as part of the project gb-taf-4610 (synthesys programme). the measurement categories follow those used by myrcha et al. (2002). contact piotr jadwiszczak piotrj@uwb.edu.pl institute of biology, university of bialystok, ciolkowskiego 1j, 15-245 bialystok, poland polar research, 2017 vol. 36, 1291086 https://doi.org/10.1080/17518369.2017.1291086 © 2017 the author(s). published by informa uk limited, trading as taylor & francis group. this is an open access article distributed under the terms of the creative commons attribution-noncommercial license (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. http://www.tandfonline.com http://crossmark.crossref.org/dialog/?doi=10.1080/17518369.2017.1291086&domain=pdf results and discussion the analysed specimen (fig. 2) represents the tarsometatarsus, a taxonomically important bone (myrcha et al. 2002) of an early penguin that exhibits an unusual combination of character states. the latter observation precludes its assignment to any known species of these birds, hence the taxonomic position can be summarized as follows. class aves linnaeus, 1758 order sphenisciformes sharpe, 1891 family spheniscidae bonaparte, 1831 (but see clarke et al. 2003) spheniscidae gen. et sp. indet. material examined the incomplete left tarsometatarsus, nrm-pz a.856, of an adult individual (fig. 2). description the fossil specimen is from a large penguin (see jadwiszczak & chapman 2011), in the size range of palaeeudyptes gunnari (wiman, 1905) and anthropornis grandis (wiman, 1905), from the la meseta formation (table 1; see also table 1 in myrcha et al. 2002). it is elongate and missing portions of the medial margin, whereas other affected parts, the proximal epiphysis as well as trochleae, are of minor importance. the intercotylar eminence is prominent. both proximal vascular foramina are small in dorsal view (unlike in anthropornis and palaeeudyptes), located at the same level relative to the main axis. the lateral one is better developed (unlike in anthropornis) and its opening is located much deeper. in plantar view, the openings are located inside the wider bony vestibules, the lateral one is more proximal. the proximal metatarsal iii is strongly lowered in dorsal view (unlike in palaeeudyptes) and the resulting concavity is clearly separated from the raised surface of the proximal epiphysis (unlike in anthropornis). the lateral intermetatarsal sulcus is well-developed and becomes shallower (smoothly, unlike in palaeeudyptes) towards its distal end which is lacking in a distal vascular foramen. the short medial sulcus has two conspicuous oval-shaped tubercles, insertion sites of the extensor retinaculum, situated mesiodistally and distally to the medial vascular foramen (unlike in palaeeudyptes and anthropornis). the insertion scar figure 1. (a) map showing the location of seymour island, la meseta formation and sampling site nrm 5; modified from jadwiszczak (2014). (b) simplified stratigraphic column of the upper la meseta formation; arrow points at the sampling horizon; abbreviations: t – turritella, cg – conglomerates and sandstones; based on data from montes et al. (2013) © instituto geográfico nacional de españa. (c) view of the sampling site location (yellow star) from cape wiman; photo (taken in february 2013) courtesy of f.j. degrange, used with permission. 2 p. jadwiszczak & t. mörs for the cranial tibial muscle is conspicuous, slightly elongated and, unlike in anthropornis and palaeeudyptes, rounded in profile. the distal metatarsal iii possesses a characteristic, subtly elevated triangular surface in dorsal view. there is also a conspicuous sharp and oblique crest just proximal to the trochlea ii. both structures, together with the medial plantar crest, form a uniquely well-developed passage for the tendon of the abductor muscle for the digit ii (see jadwiszczak 2015). the intermediate hypotarsal crests are distinctly separated. the adaxial one is low, oblique and smoothly weakens, losing its height, distally (unlike in anthropornis). the hypotarsal sulcus is narrow. distally to the medial hypotarsal crest, there is a raised rim with a slightly elevated, flat and oval-shaped, ligament/tendon attachment point. the lateral bone margin forms a long sharp edge, the lateral plantar crest. the origin site of the abductor muscle for the digit iv, located between the hypotarsus (and its distal bony continuation) and lateral plantar crest (see figure 2. tarsometatarsi of eocene penguins for seymour island, antarctic peninsula. (a–g) left-side bone, nrm-pz a.856, representing a new morphotype: (a, d) dorsal; (b) lateral; (c) plantar; (e) medial; (f) proximal; and (g) distal views of the specimen; (d) showing the reconstruction of its medial margin. (h–k) tarsometatarsi (dorsal view) representing ‘giant’ penguins from the eocene of seymour island. left-side bones: (h) ib/p/b-0483 and (j) ib/p/b-0457; reversed right-side bones: (i) nrm-pz a.22 and (k) nrm-pz a.7. polar research 3 jadwiszczak 2015), is relatively broad, like in other similarly sized penguin tarsometatarsi. the lateromedially narrowest part of the bone shaft is located distally to the level of the midpoint of the metatarsal ii and the trochlea ii is only moderately medially deflected (unlike in palaeeudyptes). remarks the specimen nrm-pz a.856 (fig. 2) is clearly longer (ca. 30%) than its counterparts in the largest living sphenisciformes assignable to the emperor penguin (aptenodytes forsteri g.r. gray, 1844), having a comparably massive trochlea iii (table 1). although its medial width is similar to that in the second largest modern sphenisciform, the king penguin (a. patagonicus j.f. miller, 1778), this is obviously because of the stronger fusion of all three metatarsals in the fossil bone (see also myrcha et al. 2002), and overall it looks more robust than those in aptenodytes (jadwiszczak, pers. obs.). in our estimation, it can therefore be assigned to the large-sized penguins or, with a high level of confidence, even to the smaller of the so-called giant sphenisciforms (jadwiszczak & chapman 2011). the reported specimen differs in many respects from the available similarly sized tarsometatarsi of eocene antarctic penguins and a vast majority of described traits were, according to our assessment, conservative in early sphenisciformes. hence, we are convinced that this unique combination of character states renders the discussed bone particularly interesting as a sole representative of a new (skeletal) morphotype of these grand birds, probably representing a new species. however, a taxonomic act would require more specimens to account for variability (see also jadwiszczak 2008) and they are currently unavailable. to conclude, we have shown that the diversity of the early antarctic penguins, already regarded as considerable, is as yet only incompletely understood. this finding, together with a number of other recent reports (such as buonoetal. 2016), substantiate the abiding importance of the la meseta formation on seymour island for the studies of fossil vertebrates that inhabited antarctica before the final break-up of gondwana. acknowledgements tm thanks marcelo reguero (la plata), the argentine antarctic institute, the argentine air force and the swedish polar research secretariat for logistic support for fieldwork on seymour island. the authors are thankful to federico j. degrange (conicet-universidad nacional de córdoba, argentina) for sharing a photo used in fig. 1. the authors are also grateful to steven emslie (university of north carolina, wilmington) and an anonymous reviewer for their constructive criticism of the submitted typescript. disclosure statement no potential conflict of interest was reported by the authors. funding this work was supported by the european community – research infrastructure action under fp7 structuring the european research area programme (synthesys project); (gb-taf-4610); the swedish research council (2009-4447). references acosta hospitaleche c. & reguero m. 2010. first articulated skeleton of palaeeudyptes gunnari from the late eocene of isla marambio (seymour island), antarctica. antarctic science 22, 289–298. buono m.r., fernández m.s., reguero m.a., marenssi s.a., santillana s.n. & mörs t. 2016. eocene basilosaurid whales from the la meseta formation, marambio (seymour) island, antarctica. ameghiniana 53, 296–315. chávez hoffmeister m. 2014. phylogenetic characters in the humerus and tarsometatarsus of penguins. polish polar research 35, 469–496. clarke j.a., olivero e.b. & puerta p. 2003. description of the earliest fossil penguin from south america and first paleogene vertebrate locality of tierra del fuego, argentina. american museum novitates 3423, 1–18. table 1. measurements of a new specimen as well as tarsometatarsi assignable to ‘giant’ fossil penguins from the eocene of seymour island and the living emperor penguin (aptenodytes forsteri g.r. gray, 1844). data are introduced as medians, ranges and numbers of specimens. asterisks mark samples with small-sized bones underrepresented, because of their incompleteness. all values are in millimetres. specimen/taxon total length length to the groove of trochlea iii mediolateral width of shaft (narrowest part) dorsoplantar thickness of trochlea iii along its groove references nrm-pz a.856 (a new morphotype) 64.2 (1) 61.6 (1) 23.7 (1) 14.1 (1) this study anthropornis 78.6 74.7–88.1 (6)* 76.3 72.8–86.0 (6)* 26.6 21.4–31.5 (9) 19.4 17.0–21.0 (6)* myrcha et al. (2002, table 1) palaeeudyptes 68.6 59.0–81.5 (29) 66.8 57.9–79.0 (31) 28.4 22.4–32.8 (31) 19.4 15.8–33.3 (41) myrcha et al. (2002, table 1) aptenodytes forsteri 46.4 41.5–48.7 (7) 45.0 40.0–47.3 (7) 28.7 26.9–30.5 (7) 13.8 13.1–14.5 (7) jadwiszczak (unpublished data) 4 p. jadwiszczak & t. mörs jadwiszczak p. 2008. an intriguing penguin bone from the late eocene of seymour island, antarctic peninsula. antarctic science 20, 589–590. jadwiszczak p. 2009. penguin past: the current state of knowledge. polish polar research 30, 3–28. jadwiszczak p. 2014. at the root of the early penguin neck: a study of the only two cervicodorsal spines recovered from the eocene of antarctica. polar research 33, 23861. doi:10.3402/polar.v33.23861. jadwiszczak p. 2015. another look at tarsometatarsi of early penguins. polish polar research 36, 343–354. jadwiszczak p. & chapman s.d. 2011. the earliest fossil record of a medium-sized penguin. polish polar research 32, 269–277. jadwiszczak p. & mörs t. 2011. aspects of diversity in early antarctic penguins. acta palaeontologica polonica 56, 269–277. kriwet j., engelbrecht a., mörs t., reguero r. & pfaff c. 2016. ultimate eocene (priabonian) chondrichthyans (holocephali, elamsobranchii) of antarctica. journal of vertebrate paleontology 36, e1160911. marenssi s.a. 2006. eustatically controlled sedimentation recorded by eocene strata of the james ross basin, antarctica. in j.e. francis et al. (eds.): cretaceous– tertiary high−latitude palaeoenvironments, james ross basin, antarctica. pp. 125–133. london: geological society. montes m., nozal f., santillana s., marenssi s. & olivero e. 2013. mapa geológico de la isla marambio (seymour), escala 1:20.000. (geological map of marambnio [seymour] island, scale 1:20.000.) serie cartográfica geocientífica antártica. madrid: instituto geológico y minero de españa, buenos aires: instituto antártico argentino. myrcha a., jadwiszczak p., tambussi c.p., noriega j.i., gaździcki a., tatur a. & del valle r.a. 2002. taxonomic revision of eocene antarctic penguins based on tarsometatarsal morphology. polish polar research 23, 5–46. reguero m., goin f., acosta hospitaleche c., dutra t. & marenssi s. 2013. late cretaceous/paleogene west antarctica terrestrial biota and its intercontinental affinities. dordrecht: springer. polar research 5 https://doi.org/10.3402/polar.v33.23861 abstract material and methods results and discussion material examined description remarks acknowledgements disclosure statement funding references doi:10.3402/polar.v35.28516 r e s e a r c h / r e v i e w a r t i c l e gastrointestinal helminths of adélie penguins (pygoscelis adeliae) from antarctica julia inés diaz,1 bruno fusaro,1,2 lucrecia longarzo,1 néstor rubén coria,2 virginia vidal, 3 verónica d’amico 4 & andrés barbosa 3 1 centro de estudios parasitológicos y de vectores, facultad de ciencias naturales y museo, universidad nacional de la plata, consejo nacional de investigaciones cientı́ficas y técnicas, la plata, buenos aires, argentina 2 proyecto aves, instituto antártico argentino, dirección nacional del antártico, buenos aires, argentina 3 departamento de ecologı́a evolutiva, museo nacional de ciencias naturales, consejo superior de investigaciones cientı́ficas, madrid, spain 4 centro nacional patagónico, consejo nacional de investigaciones cientı́ficas y técnicas, puerto madryn, chubut, argentina keywords parorchites zederi; stegophorus macronectes; tetrameres sp.; parasites; ecosystem health. correspondence julia inés diaz, centro de estudios parasitológicos y de vectores, 120 s/n, entre 61 y 62, (1900) la plata, buenos aires province, argentina. e-mail: jidiaz@cepave.edu.ar abstract knowledge about parasitic organisms in antarctica is scarce and fragmentary. the study reported here adds to the knowledge of gastrointestinal parasites of the adélie penguin (pygoscelis adeliae) (sphenisciformes), from 25 de mayo/ king george island (south shetlands), bahia esperanza (hope bay) and avian island (antarctica). thirty-five freshly dead specimens (20 chicks and 15 adults) were collected from december 2007 to december 2014 and examined for internal macroparasites. three adult parasite species were found: one cestoda, parorchites zederi, and two nematoda, stegophorus macronectes and tetrameres sp. immature tetrabothrius sp. were found in hosts from avian island. helminth communities are known to be related to host feeding behaviours. low parasite richness observed in adélie penguins could be related to the stenophagic and pelagic diet of this host species, which feeds almost exclusively on krill. almost all animals are affected by some kind of parasites at some time during their life (bush et al. 2001). by affecting the assimilation of nutrients, reproduction and behaviour parasites can be an important factor modulating host populations (fonteneau et al. 2011). examples of the impacts of parasites include the die-offs involving several ring-billed gulls (larus delawarensis) in the st. lawrence river and the mortality of some wild-caught in brant that were maintained in captivity on a freshwater pond (dellaire 2006). an unidentified species of schistosome and a mixed infection with trichobilarzia and dendrotobilharzia were considered the primary causes of death in these two populations, respectively (huffman & fried 2008). impacts of parasites at the scale of host populations have been both extensively modelled and experimentally demonstrated for trichostrongylus tenuis in red grouse in northern england (tompkins 2008). in marine ecosystems, the parasite community of a host species reflects the presence of other organisms (intermediate hosts) that are involved in their life cycle through trophic interactions, making parasites natural markers of changes in biodiversity (marcogliese 2005). also, environmental changes, including climate change, can result in a variation in the distribution, abundance or virulence of parasites and pathogens (daszak et al. 2000; harvell et al. 2002; epstein et al. 2003). as excellent indicators of ecosystem health, parasites are also potentially useful as early-warning indicators of environmental perturbations. therefore, baseline information on the parasitofauna is very important to understand possible modifications in a changing world. knowledge about the parasites and diseases of antarctic birds is limited and fragmentary (barbosa & palacios 2009), even in the case of penguins, which represent around 80% of the vertebrate biomass and are the most studied birds in antarctica (barbraud & weimerskirch 2006). recent studies have expanded our knowledge about parasites of some antarctic penguin species, providing taxonomic information but also data on prevalence and intensities (fonteneau et al. 2011; vidal et al. 2012; polar research 2016. # 2016 j.i. diaz et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 28516, http://dx.doi.org/10.3402/polar.v35.28516 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/28516 http://dx.doi.org/10.3402/polar.v35.28516 diaz et al. 2013; gonzález-acuña et al. 2013). however, despite the fact that the adélie penguins (pygoscelis adeliae [hombron & jacquinot]) (aves, spheniscidae) are probably the best studied of all penguin species, data on their parasites remain fragmentary (kerry et al. 1999; barbosa & palacios 2009). the adélie penguin is one of more abundant marine birds in the antarctic ecosystem (croxall & prince 1980), with an estimated population of approximately 3.8 million breeding pairs (lynch & larue 2014). the species has a circumpolar distribution, between 468 and 778s (woehler 1993). adults begin to arrive on the coast in late september or early october and the breeding season lasts until february. adélie penguins feed along the marginal ice zone, which extends for approximately 100 km from the edge of the pack ice (croxall et al. 2002), and are susceptible to changes in the distribution and abundance of krill and fish (schofield et al. 2010; sailley et al. 2013), which are their main prey species (coria et al. 1995; libertelli et al. 2003). during the winter, adélie penguins are obligate inhabitants of the pack ice (trivelpiece et al. 1987). in this paper, we describe the gastrointestinal helminth community of the adélie penguin, analysing specimens from three reproductive populations established in the antarctic peninsula and islands around it. given that any change in parasite diversity may be a sign of ‘‘ecosystem distress syndrome’’ (rapport 2007), this information will be an important baseline in terms of ecosystem health. materials and methods a total of 35 adélie penguins freshly dead from natural causes were collected from different locations along the antarctic peninsula and associated islands (stranger point, 25 de mayo/king george island, south shetland islands during summers from 2007 to 2012; bahia esperanza/hope bay during the summers of 2013/14 and 2014/15; and avian island during the summer of 2009/10 [fig. 1, table 1]). causes of death were unknown although we can exclude predation. digestive tracts were immediately removed, placed in plastic bags and frozen at �208c or fixed in 10% formalin until parasitological examination could be carried out. viscera were separated into oesophagus, stomach (glandular proventriculus and muscular gizzard), intestine and cloaca. gastrointestinal helminths were removed under a stereomicroscope, fixed in 5% formalin and preserved in 70% ethanol. cestodes were stained in semichon’s carmine, dehydrated in a graded ethanol series, cleared in methyl salicylate and mounted in canada balsam. nematodes were cleared in 25% glycerine ethanol. all specimens were studied using an optical microscope. some specimens were dehydrated, dried by the critical point method, gold coated, observed and photographed using a scanning electron microscope (jsmt 6360 lv, jeol). the terms p, mi and s were interpreted according to bush et al. (1997). the mi and s are followed by the range. specimens were identified following keys and specific bibliography (johnston & mawson 1945; delymure 1955; petter 1959; yamaguti 1959, 1961; chabaud 1974; cielecka et al. 1992; khalil et al. 1994) and deposited in the helminthological collection of the museo de la plata, la plata, argentina (mlp he 7032, 7033, 7034). tests were carried out using quantitative abbreviations in this article p: prevalence, i.e., the number of hosts infected with at least one parasite species divided by the number of hosts examined mi: mean intensity, i.e., the total number of indivi duals of a parasite species found in a sample divided by the number of hosts infected s: richness, i.e., the number of total parasite species in the sample fig. 1 localities sampled: (1) stranger point, isla 25 de mayo/king george island, (2) bahı́a esperanza/hope bay, (3) avian island. helminths from adélie penguins j.i. diaz et al. 2 (page number not for citation purpose) citation: polar research 2016, 35, 28516, http://dx.doi.org/10.3402/polar.v35.28516 http://www.polarresearch.net/index.php/polar/article/view/28516 http://dx.doi.org/10.3402/polar.v35.28516 parasitology 3.0 budapest software (rózsa et al. 2000). chi-square test and unconditional test were applied to test differences in p between species of penguins, age groups and localities. mi differences were estimated by bootstrap test. p values b0.05 were considered significant. data from chinstrap and gentoo penguins were taken from vidal et al. (2012) and diaz et al. (2013), respectively. results a total of 471 helminths were recovered from all hosts analysed, belonging to three adult parasite species: the cestode parorchites zederi (baird 1853) (dilepididae) from the intestine, and two nematode species, stegophorus macronectes (johnston & mawson 1942) (acuariidae) in the oesophagus and stomach and tetrameres sp. (tetrameriidae) in the glandular stomach. also, immature specimens identified as tetrabothrius sp. were recovered from the intestine of penguins from avian island. of the total penguins examined, 51.4% were parasitized by at least one of the species identified (mi �26, 1�151). parorchites zederi were found free in the lumen or profoundly fixed in the mucosa forming nodular lesions (p �17.1%; mi �4.8, 1�12). specimens were identified on the basis of features of the scolex and proglottids and the presence of a pseudoscolex. stegophorus macronectes (p �28.6%; mi �42.3, 1�150) were identified based on the morphology of ornamental cephalic structures, cephalic collar and deirids, position of the vulva in females, papillae distribution and spicules in males (see vidal et al. 2016). tetrameres sp. were found in three adult host (p �8.6%; mi �5.3, 1�13) and were identified by features of the buccal capsule and spination of the body surface. two immature tetrabothrius sp. specimens were found only in two hosts. specific identification was not possible since specimens were immature. most infracommunities were composed of only one parasite species, s �1 (1�2). some 83% of infections were monospecific (53% with s. macronectes, 20% with p. zederi, 20% with tetrameres sp. and 7% with tetrabothrius sp.), whereas 17% of infected penguins were parasitized by two different species (66% with s. macronectes and p. zederi, 33% with p. zederi and tetrabothrius sp.). there were no specimens parasitized by more than two species. composition and ecological parameters by locality and age group are shown in table 1. the richness of the component community was greater in adults than chicks (s �4 versus s �2). p was greater in adults than chicks (p �0.02). no other significant difference was observed between groups. discussion penguins are pelagic and stenophagic birds that are characterized by a low helminth richness (hoberg 2005; fonteneau et al. 2011). two of the parasite species registered in this work are widely distributed among antarctic penguins. parorchites zederi is a very common parasite in the three pygoscelid species: adélie penguin, chinstrap and gentoo penguins (cielecka et al. 1992; hoberg 2005; barbosa & palacios 2009; vidal et al. 2012; diaz et al. 2013). it is the only member of the order cyclophyllidea in pelagic systems (hoberg 2005). these cestodes penetrate the intestinal mucosa reaching the serosa, where they generate large nodules associated with lesions (ippen et al. 1981; tzvetkov et al. 1999; martin 2015; martin et al. in press). the other common parasite is the nematode stegophorus macronectes, which has a wide host and geographical distribution (barbosa & palacios 2009). among penguins, this species has been reported to inhabit the oesophagus and stomach in the three pygoscelid species, and in the rockhopper penguin (eudyptes chrysocome [forster]) and macaroni penguin (eudyptes crysolophus [brandt]) (johnston & mawson 1945; mawson 1953; zdzitowiecki & drózdz 1980; vidal et al. 2012; diaz et al. 2013: vidal et al. 2016). euphausiid species have been recorded as suitable intermediate/paratenic hosts of both of the dominant parasite species found in this study (anderson 2000; hoberg 2005). the adélie penguin diet in the south shetlands islands area is composed mainly of the pelagic table 1 parasite composition and ecological parameters of pygoscelis adeliae by locality and age group. stranger point 62814’ s; 58839’ w bahia esperanza 63824’ s; 56859’ w avian island 67846’ s; 68864’ w adults chicks total adults chicks total adults chicks adults host analysed [n a (p; mi)] 15 (73; 21) 20 (35; 35) 26 (35; 30) 7 (57; 6) 19 (26; 48) 7 (71; 40) 6 (83; 40) 1 2 (100; 1.5) parorchites zederi (p; mi) 20; 5 15; 5 19; 6 29; 6 16; 5 100; 1 stegophorus macronectes (p; mi) 27; 49 30; 38 27; 34 14; 9 21; 56 43; 63 50; 63 tetrameres sp. (p; mi) 20; 5 4; 2 14; 2 29; 7 33; 7 tetrabothrius sp. (p; mi) 13; 1 50; 1 a number of analysed hosts. j.i. diaz et al. helminths from adélie penguins citation: polar research 2016, 35, 28516, http://dx.doi.org/10.3402/polar.v35.28516 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/28516 http://dx.doi.org/10.3402/polar.v35.28516 crustacean euphausia superba (krill), representing 98.5% by weight of the total prey items in the stomach contents (coria et al. 1995). it is highly likely that e. superba acts as the intermediate host of the dominant parasitic species, p. zederi and s. macronectes, which use food webs to infect definitive hosts. species of tetrameres parasitize different orders of birds, but because the specimens typically are hidden in the proventricular glands, their presence is often underreported. tetrameres wetzeli (schmidt 1965) is the only species of this genus parasitizing penguin hosts (fonteneau et al. 2011; diaz et al. 2013). life cycles of tetrameres species also include crustaceans as intermediate hosts (hoberg 2005). finally, species of tetrabothrius are widely distributed among penguins, for example, t. lutzi from the magellanic penguin (spheniscus magellanicus [forster]), t. pauliani and t. joubini from chinstrap penguin and t. wrighti from the emperor penguin (aptenodytes forsteri gray) (barbosa & palacios 2009; diaz et al. 2010; fonteneau et al. 2011; vidal et al. 2012). life cycles of tetrabothrius species includes mainly fish as paratenic hosts (hoberg 2005). although the low sample size of penguins analysed from each age group and from the locations of esperanza/ hope bay and avian island precludes making robust conclusions, it is possible to state that adults and chicks share the same parasitofauna because they feed on the same prey items. however, the higher s and p observed in adults are in agreement with what is expected considering that older hosts have more time to be exposed to parasites because transmission does not decrease with age, transmission rates are low and/or parasite mortality does not increase with age (hudson & dobson 1997; morand & deter 2009). tetrabothrius sp. was found in avian island, but not in the other two localities. this could be associated with a differentiation in the diet related with geographical distribution. in fact, it is known that in the most southern colonies the diet of adélie penguin includes a higher proportion of fish than in northern populations (coria et al. 1995; libertelli et al. 2003; tierney et al. 2008). this may explain the finding of tetrabothrius sp. in hosts from avian island. other species of this genus were reported in adélie penguins inhabiting the south shetlands, with authors considering these records as rare findings at this latitude (cielecka et al. 1992). the present study reports the genus tetrameres for first time in the adélie penguin, and adds to those already recorded previously in other penguins. previous authors reported other helminth species in the adélie penguin in different areas of antarctica (e.g., corynosoma spp., contracaecum spp., streptocara sp.) (mawson 1953; fredes et al. 2008; barbosa & palacios 2009; brandao et al. 2014). however, it could be assumed that many of these species might represent occasional and/or accidental findings because almost all of them consisted of a few immature parasite specimens (cielecka et al. 1992). taking into account that phylogeny is an important factor that modulates the host�parasite relationship (poulin & morand 2004), it is common to find the same parasite species among hosts of the same genus. the adélie penguin shares the dominant helminth species (i.e., p. zederi and s. macronectes) with their two congeneric species, gentoo and chinstrap penguins (vidal et al. 2012; diaz et al. 2013). the parasite community of the adélie penguin shows a low richness similar to the other pygoscelid species, probably as a result of the narrow diet spectrum based mainly on krill (see vidal et al. 2012; diaz et al. 2013; d’amico et al. 2014). finally, the presence of p. zederi and s. macronectes as dominant species (i.e., high p and mi) in all groups of host analysed is indicative of a strong intake of crustaceans in all localities and age classes. the presence of tetrabothrius in those hosts form avian island could be associated with an increase of fish in the diet in the southern areas. conclusions knowledge about parasites and diseases in antarctic fauna is important in assessing potential changes due to diet shifts in relation to climate. here we report baseline data about the gastrointestinal parasite fauna of the adélie penguin in different localities along the antarctic peninsula. this information, together with that arising from previous and future studies of different species of penguins, will be useful for the study of ecosystem health in a changing world. acknowledgements we very much appreciate the hospitality and logistic support of the argentine antarctic base carlini, the argentinean transports and the spanish polar ship las palmas which provided us transport to avian island. we also appreciate the logistic support provided by the instituto antártico argentino and the maritime technology unit. we especially thank john mike kinsella for revising the english and critically reading the manuscript. financial support was given by the dirección nacional del antártico (dna), the spanish ministry of economy and competitiveness, and european regional development helminths from adélie penguins j.i. diaz et al. 4 (page number not for citation purpose) citation: polar research 2016, 35, 28516, http://dx.doi.org/10.3402/polar.v35.28516 http://www.polarresearch.net/index.php/polar/article/view/28516 http://dx.doi.org/10.3402/polar.v35.28516 fund (projects cgl2007-60369 and ctm2011-24427). permission to work in the antarctic study area and to handle penguins was given by dna and the spanish polar committee. vv was supported by a phd grant from the spanish council of scientific research (jaepre0801053). jid was partially supported by the universidad nacional de la plata (n628 and n758) and consejo nacional de investigaciones cientı́ficas y técnicas, argentina (pip698). this is a contribution to the pinguclim project. references anderson r.c. 2000. nematode parasite of vertebrates: their development and transmission. 2nd edn. wallingford: cab international. barbosa a. & palacios m.j. 2009. health of antarctic birds: a revision of their parasites, pathogens and diseases. polar biology 32, 1095�1115. barbraud c. & weimerskirch h. 2006. antarctic birds breed later in response to climate change. proceedings of the national academy of sciences of the united states of america 103, 6248�6251. brandao m.l., moreira j. & luque j.l. 2014. checklist of platyhelminthes, acanthocephala, nematoda and arthropoda parasitizing penguins of the world. check list 10, 562�573. bush a.o., fernández j.c., esch g.w. & seed j.r. 2001. parasitism. the diversity and ecology of animal parasites. cambridge: cambridge university press. bush a.o., lafferty k.d., lotz j.m. & shostak a.w. 1997. parasitology meets ecology on its own terms: margolis et al. revisited. journal of parasitology 83, 575�583. chabaud a.g. 1974. keys to genera of the order spirurida. in r.c. anderson et al. (eds.): keys to the nematode parasites of vertebrates. pp. 29�58. farnham royal: commonwealth agricultural bureaux. cielecka d., wojciechowska a. & zdzitowiecki k. 1992. cestodes from penguins on king george island (south shetlands, antarctic). acta parasitologica 37, 65�72. coria n.r., fontana r., vivequin s. & spairani h. 1995. diet of adélie penguins pygoscelis adeliae during the posthatching period at stranger point, king george island, south shetland island, antarctica. museo regionale di scienze naturali bollettino 132, 377�383. croxall j.p. & prince e.d. 1980. food, feeding ecology and ecological segregation of seabirds at south georgia. biological journal of the linnean society 14, 103�131. croxall j.p., trathan p.n. & murphy e.j. 2002. environmental change and antarctic seabird populations. science 297, 1510�1514. d’amico v.l., bertelotti m., diaz j.i., coria n., vidal v. & barbosa a. 2014. leucocyte levels in some antarctic and non-antarctic penguins. ardeola 61, 145�162. daszak p., cunningham a.a. & hyatt a.d. 2000. emerging infectious diseases of wildlife: threats to biodiversity and human health. science 287, 443�449. dellaire a.d. 2006. schistosomiasis-related mortality in ring billed ducks. wildlife health center newsletter 12, 9. delymure s.l. 1955. helminthofauna of marine mammals (ecology and phylogeny). jerusalem: israel program for scientific translations. diaz j.i., cremonte f. & navone g.t. 2010. helminths of the magellanic penguin, spheniscus magellanicus (sphenisciformes), during the breeding season in patagonian coast, chubut, argentina. comparative parasitology 77, 172�177. diaz j.i., fusaro b., longarzo l., coria n.r., vidal v., jerez s., ortiz j. & barbosa a. 2013. gastrointestinal helminths of gentoo penguins (pygoscelis papua) from stranger point, 25 de mayo/king george island, antartica. parasitology research 112, 1877�1881. epstein p.r., chivian e. & frith k. 2003. emerging diseases threaten conservation. environmental health perspectives 111, a506�a507. fonteneau f., geiger s., marion l., le maho y., robin j.p. & kinsella j.m. 2011. gastrointestinal helminths of king penguins (aptenodytes patagonicus) at crozet archipelago. polar biology 34, 1249�1252. fredes f., raffo e., muñoz p., herrera m. & godoy c. 2008. fauna parasitaria gastrointestinal en el pingüino adelia (pygoscelis adeliae) de zona antártica especialmente protegida (zaepn 150). (gastrointestinal fauna in an adélie penguin [pygoscelis adeliae] in antarctic specially protected area 150.) parasitologı́a latinoamericana 63, 64�68. gonzález-acuña d., hernández j., moreno l., herrmann b., palma r., latorre a., medina-vogel g., kinsella j.m., martı́n n., araya k., torres i., fernandez n. & olsen b. 2013. health evaluation of wild gentoo penguins (pygoscelis papua) in the antarctic peninsula. polar biology 36, 1749�1760. harvell c.d., mitchell c.e., ward j.r., altizer s., dobson a.p., ostfeld r.s. & samuel m.d. 2002. climate warming and disease risks for terrestrial and marine biota. science 296, 2158�2163. hoberg e.p. 2005. economic, environmental and medical importance: marine birds and their helminth parasites. in k. rohde (ed.): marine parasitology. pp. 414�421. sydney: scientific and industrial research organisation. hudson p.j. & dobson a.p. 1997. host-parasite processes and demographic consequences. in d.h. clayton & j. moore (eds.): host�parasite evolution. general principles and avian models. pp. 128�154. oxford: oxford university press. huffman j. & fried b. 2008. schistosomes. in c.t. atkinson et al. (eds.): parasitic diseases of wild birds. pp. 246�260. ames, ia: wiley-blackwell. ippen r., odening k. & henne d. 1981. cestoden (parorchites zederi) und sarkosporidienbefall (sarcocystis sp.) bei penguinen der slid-shetland inseln (cestodes (parorchites zederi) and sarcosporidia infestation (sarcocystis sp.) in penguins at south shetland island). in r. ippen & h.-d. schröder (eds.): verhandlung des xxiii internationalen symposiums über die erkrankungen der zootiere vom 24. juni bis 28. juni 1981 in halle/saale. pp. 203�210. berlin: akademischer verlag. j.i. diaz et al. helminths from adélie penguins citation: polar research 2016, 35, 28516, http://dx.doi.org/10.3402/polar.v35.28516 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/28516 http://dx.doi.org/10.3402/polar.v35.28516 johnston t.h. & mawson p.m. 1945. parasitic nematodes. banzare reports series b 2, 73�160. kerry k., riddle m. & clarke k. 1999. diseases of antarctic wildlife. report to the scientific committee on antarctic research (scar) and the council of managers of national antarctic programs (comnap). hobart: australian antarctic division. khalil l.f., jones a. & bray r.a. 1994. key to the cestode parasite of vertebrates. albans: cabi publishing. libertelli m.m., coria n. & marateo g. 2003. diet of the adélie penguin during three consecutive chick rearing periods at laurie island. polar research 24, 133�142. lynch h.j. & larue m.a. 2014. first global census of the adélie penguin. the auk 131, 457�466. marcogliese d.j. 2005. parasites of the superorganism: are they indicators of ecosystems health? international journal for parasitology 35, 705�716. martin m.a., ortiz j.m., seva j., vidal v., valera f., benzal j., cuervo j.j., de la cruz c., belliure j., martı́nez a.m., diaz j.i., motas m., jerez s., d’amico v. & barbosa a. in press. mode of attachment and pathology caused by parorchites zederi in three species of penguins: pygoscelis papua, pygoscelis adeliae, and pygoscelis antarctica in antarctica. journal of wildlife diseases. doi: http://dx.doi.org/10.7589/2015-07-200 martin m.a. 2015. alteraciones morfológicas asociadas a macroparásitos digestivos en los pingüinos pigoscélidos. (digestive macroparasites associated with morphological alterations in pygoscelid penguins.) phd thesis, university of murcia. mawson p. 1953. parasitic nematoda collected by the australian national antarctic research expedition: heard island and macquarie island, 1948�1951. parasitology 43, 291�297. morand s. & deter j. 2009. parasitism and regulation of the host population. in f. thomas et al. (eds.): ecology and evolution of parasitism. pp. 83�105. oxford: oxford university press. petter a.j. 1959. redescription de paryseria adeliae johnston, 1938. remarques sur le genre paryseria et les genres voisins rusguniella, aviculariella, proyseria (gen. nov.), seuratia. (notes on paryseria and related genera rusguniella, aviculariella, proyseria (gen. nov.), seuratia.) annales de parasitologie humaine et comparée 34, 322�330. poulin r. & morand s. 2004. parasite biodiversity. washington, dc: smithsonian books. rapport d.j. 2007. sustainability science: an ecohealth perspective. sustain science 2, 77�84. rózsa l., reiczigel j. & majoros g. 2000. quantifying parasites in samples of hosts. journal of parasitology 86, 228�232. sailley s.f., ducklow h.w., moeller h.v., fraser w.f., schofield o.m., steinberg d.k., garzio l.m. & doney s.c. 2013. carbon fluxes and pelagic ecosystem dynamics near two western antarctic peninsula adélie penguin colonies: an inverse model approach. marine ecology progress series 492, 253�272. schofield o., ducklow h.w., martinson d.g., meredith m.p., moline m.a. & fraser w.r. 2010. how do polar marine ecosystems respond to rapid climate change? science 328, 1520�1523. tierney j.e., russell j.m., huang y., sinninghe damsté j.s., hopmans e.c. & cohen a.s. 2008. northern hemisphere controls on tropical southeast african climate during the past 60,000 years. science 322, 252�255. tompkins d.m. 2008. trichostrongylus. in c.t. atkinson et al. (eds.): parasitic diseases of wild birds. pp. 316�325. ames, ia: wiley-blackwell. trivelpiece w.z., trivelpiece s.g. & volkman n.j. 1987. ecological segregation of adélie, gentoo and chinstrap penguins at king george island, antarctica. ecology 68, 351�361. tzvetkov y., kril a., georgiev b.b. & chipev n.h. 1999. morphology of lesions in the intestinal wall of the gentoo penguin, pygoscelis papua, caused by parorchites zederi (cestoda: dilepididae). in v. golemansky & n. chipev (eds.): (eds.): bulgarian antarctic research. vol. 2. pp. 62�67. sofia: pensoft publishers. vidal v., ortiz j., diaz j.i., de ybañez m.r., amat m.t., palacios m.j., benzal j., valera f., de la cruz c., motas m. & barbosa a. 2012. gastrointestinal parasites in chinstrap penguins from deception island, south shetlands, antarctica. parasitology research 111, 723�727. vidal v., ortiz j., diaz j.i., zafrilla b., bonete m.j., de ybañez m.r.r., palacios m.j., benzal j., valera f., de la cruz c., motas m., bautista v., machordom a. & barbosa a. 2016. morphological, molecular and phylogenetic analyses of the spirurid nematode stegophorus macronectes (johnston & mawson, 1942). journal of helminthology 90, 214�222. woehler e.j. 1993. the distribution and abundance of antarctic and subantarctic penguins. cambridge: scientific committee on antarctic research. yamaguti s. 1959. systema helminthum. vol. 2. the cestodes of vertebrates. new york: interscience publishers. yamaguti s. 1961. systema helminthum. vol. 3. the nematodes of vertebrates. new york: interscience publishers. zdzitowiecki k. & drózdz j. 1980. redescription of stegophorus macronectes (johnston et mawson, 1942) and description of stegophorus arctowskii sp. n. (nematoda, spirurida) from birds of south shetlands (the antarctic). acta parasitologica 26, 205�212. helminths from adélie penguins j.i. diaz et al. 6 (page number not for citation purpose) citation: polar research 2016, 35, 28516, http://dx.doi.org/10.3402/polar.v35.28516 http://dx.doi.org/10.7589/2015-07-200 http://www.polarresearch.net/index.php/polar/article/view/28516 http://dx.doi.org/10.3402/polar.v35.28516 doi:10.3402/polar.v33.23896 r e s e a r c h / r e v i e w a r t i c l e variability of humidity conditions in the arctic during the first international polar year, 1882�83 przemysław wyszyński & rajmund przybylak department of meteorology and climatology, faculty of earth sciences, nicolaus copernicus university, lwowska 1, pl-87-100 toruń, poland keywords humidity conditions; arctic; early instrumental period; historical climatology. correspondence przemysław wyszyński, department of meteorology and climatology, faculty of earth sciences, nicolaus copernicus university, lwowska 1, pl-87-100 toruń, poland. e-mail: przemyslaw. wyszynski@umk.pl abstract of all the early instrumental data for the arctic, the meteorological data gathered during the first international polar year, in 1882�83 (ipy-1), are the best in terms of coverage, quality and resolution. research carried out during ipy-1 scientific expeditions brought a significant contribution to the development of hygrometry in polar regions at the end of the 19th century. the present paper gives a detailed analysis of a unique series of humidity measurements that were carried out during ipy-1 at hourly resolutions at nine meteorological stations, relatively evenly distributed in the high arctic. it gives an overall view of the humidity conditions prevalent in the arctic at that time. the results show that the spatial distribution of atmospheric water vapour pressure (e) and relative humidity (rh) in the arctic during ipy-1 was similar to the present. in the annual course the highest values of e were noted in july and august, while the lowest occurred in the cold half of the year. in comparison to present-day conditions (1961�1990), the mean values of rh in the ipy-1 period (september 1882 to july 1883) were higher by 2.4�5.6%. most of the changes observed between historical and modern rh values are not significant. the majority of historical daily rh values lie between a distance of less than two standard deviations from current long-term monthly means. to access the supplementary material for this article, please see the supplementary files under article tools online. water vapour is a driving force in a number of atmospheric processes. being the main greenhouse gas, it has a significant influence on the global climate and its changes. understanding the variability of water vapour concentration and its causes is extremely important in order to comprehend the way in which the earth’s climate system works. according to the clausius�clapeyron equation, increasing the temperature of air leads to an exponential growth of the water-holding capacity of the atmosphere. correspondingly, a 18c increase in air temperature will raise the saturated vapour pressure by 7% (willett et al. 2008). in the earth’s climate system, polar areas are considered to be particularly important regions which are first to respond to global climate changes and where the responses are the strongest. the recently observed considerable warming of the arctic (symon et al. 2005; przybylak 2007) is causing the melting of sea ice and an increase in water vapour in the atmosphere (serreze et al. 2012), which may trigger positive feedback, as a result of which the air temperature will continue to rise (serreze & barry 2011). to predict the extent of climate changes in the future, we need to reconstruct their historical course in as detailed a manner as possible. in recent years, one of the branches of climatology, historical climatology, has seen dynamic growth in a lot of countries. in order to enhance research work in this area, in a number of cases international cooperation has been established, good examples of which are the atmospheric circulation reconstructions over the earth programme (allan et al. 2011) and the old weather project (http://www.oldweather.org/), both intended to discover, collect and digitize historical weather data for the whole world. in the arctic, regular instrumental observations started relatively late*mainly after 1920*compared with other polar research 2014. # 2014 p. wyszyński & r. przybylak. this is an open access article distributed under the terms of the creative commons attributionnoncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/23896/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23896/0 http://www.oldweather.org/ http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 areas of the globe (for more details see przybylak et al. 2010; przybylak et al. 2013). this makes all available data from before 1920 significant and indispensable to evaluate the climate fluctuations and changes in the arctic, encouraging researchers to make an effort and retrieve the data concerning the early instrumental period for the arctic and the subarctic region (kay 1995; przybylak 2000; klingbjer & moberg 2003; polyakov et al. 2003; wood & overland 2003, 2006; lüdecke 2004, 2005; przybylak 2004; przybylak & dzierżawski 2004; przybylak & vizi 2004, 2005; klimenko & astrina 2006; vinther et al. 2006; klimenko 2008, 2010; vı́zi 2008; brohan et al. 2010; przybylak et al. 2010; wood et al. 2010; wilkinson et al. 2011; wyszyński 2012; przybylak et al. 2013). the majority of this work has been aimed at reconstruction of the air temperature and atmospheric pressure. measurements made as part of expeditions mounted during the first international polar year 1882�83 (ipy-1) provide a vital contribution to the discovery of knowledge about the arctic climate of the 19th century. moreover, of all the early instrumental data available for the area, they are definitely the best in terms of coverage, quality, resolution and other aspects. so far, the literature does not offer any detailed studies of the humidity of air in the arctic during the early instrumental times, due to the fact that it was extremely difficult to take reliable measurements of atmospheric humidity in the polar regions with negative air temperatures prevailing most of the year. the problem is addressed in the works of koch & wegener (1930), loewe (1935), sverdrup (1935) and golcman (1939, 1949). in this paper, a detailed analysis is provided of a unique series of air humidity measurements taken during ipy-1, which improves our knowledge of humidity conditions in the arctic at that time. area, data and methods during ipy-1 in 1882�83, 12 main and a large number of auxiliary research stations were operating in the northern hemisphere (mainly on the labrador peninsula); for more details see barr (2008) and barr & lüdecke (2010). this study makes use of data from nine stations representing the so-called high arctic (fig. 1), whose boundaries and division into climatic regions were assigned in accordance with the atlas of the arctic (trešnikov 1985). the evenly distributed stations (table 1, fig. 1) of godthåb, jan mayen, kapp thordsen, malye karmakuly, sagastyr, point barrow, lady franklin bay, kingua fjord and kara sea are representative of nearly all climatic regions of the arctic. the kara sea data series includes meteorological observations made during the drift of the dutch vessel the ss varna, which moved from vaygach island in the east�north-east direction, along the yamal current. between 15 january and 31 july 1883, measurements were taken in the vicinity of a building erected on pack ice in case the ship was destroyed by ice, which actually happened on 21 january that year. most of the observations and meteorological measurements were made in the area situated between 70800?n and 71845?n, and 62829?e and 65825?e (table 2). the dutch steam ship eventually sank in the icy waters of the kara sea on 24 july 1883 (for more details see snellen & ekama 1910; barr 2008). according to the recommendations of the international polar commission (st. petersburg 1882), meteorological measurements were to be performed at 1-h intervals (table 1). however, in the harsh polar conditions not all of the expeditions managed to comply with this recommendation. at most of the analysed stations, the measurements were recorded according to mean local time (table 3), the only exception here being two american stations (lady franklin bay and point barrow), where the records refer to washington local time. this is why the references table 1 geographical coordinates of the meteorological international polar year 1882�83 (ipy-1) stations, resolution of the data, height of instruments and list of source materials. location ipy-1 stations 8 l data resolutiona height of psychrometer above ground level (m) source godthåb 64811?n 51844?w 24 times per day 1.95 paulsen 1886 jan mayen 71800?n 8828?w 3.05 von wohlgemuth 1886 kapp thordsen 78828?n 15843?e 2.00 ekholm 1890 malye karmakuly 73822?n 52836?e 2.80 lenz 1886b kara sea drift of varna b 3.00 snellen & ekama 1910 sagastyr 73822?n 124805?e 2.40 lenz 1886a point barrow 71814?n 156840?w 1.23 ray 1885 lady franklin bay 81844?n 64845?w 1.52 greely 1886 kingua fjord 66836?n 67819?w 2.00 neumayer & börgen 1886 adetailed information concerning the gaps and changed measurement intervals at individual stations are provided in the explanatory notes to tables 4 and 6. b steamship. see table 2. humidity conditions in the arctic during the first ipy p. wyszyński & r. przybylak 2 (page number not for citation purpose) citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 from lady franklin bay and point barrow were corrected by �1 h and �5 h, respectively, to reduce them to the common mean local time. about 20-min deviations from the local time at kapp thordsen and on the kara sea were considered hardly significant, and remained unadjusted. the quality and correctness of the data gathered during the ipy-1 expeditions were already being verified during the expeditions themselves. furthermore, corrections were made to the measurements to accommodate the methodology accepted at the third meeting of the international polar commission in st. petersburg, held from 1 to 8 august 1881 (wild 1882). it should be noted that properly trained members of the individual expeditions took the measurements themselves. the instruments had been carefully calibrated at national meteorological centres, such as the kew observatory near london and the central physical observatory of st. petersburg in russia. after the expeditions, the instruments were verified at the same facilities. atmospheric humidity can be measured in several ways. during ipy-1, air humidity was determined using both the psychrometric (measuring e: pressure of the current water vapour content of the air) and hygrometric methods (measuring rh: relative humidity, or the ratio of fig. 1 location of meteorological stations operating in the arctic in the period of the first international polar year, in 1882�83. the arctic and its climatic regions are defined according to trešnikov (1985). the southern arctic boundary has been delimited based on analysis using long-term mean values of all meteorological variables, their seasonal cycles and variability characteristics. the boundary of the arctic is shown as the thick solid line (i); boundaries between climatic regions are indicated with thick dashed lines (ii); the arctic circle is indicated with a thin dashed line. the stations comprised the following: godthåb (1), jan mayen (2), kapp thordsen (3), malye karmakuly (4), kara sea (5), sagastyr (6), point barrow (7), lady franklin bay (8) and kingua fjord (9). table 2 geographical coordinates of the drift of the steamer varna; highest (81, l1) and lowest (82, l2) latitude and longitude of the varna in each month. year month 81 n 82 n l1 e l2 e 1882 aug 73825? 69821? 59853? 50832? sep 70815? 69855? 64821? 60825? oct 70824? 70800? 64835? 63849? nov 70827? 70811? 64807? 64806? dec 70854? 70821? 65809? 64829? 1883 jan 71803? 70853? 65820? 64804? feb 71820? 71801? 64853? 63857? mar 71839? 71820? 65811? 64834? apr 71845? 71829? 65825? 64837? may 71835? 71819? 64819? 63852? jun 71820? 71811? 64810? 63830? jul 71811? 71803? 63816? 62836? aug 71810? 70804? 62829? 58830? source: snellen & ekama (1910). p. wyszyński & r. przybylak humidity conditions in the arctic during the first ipy citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 the actual pressure of the water vapour [e] in the air to the pressure of the saturated water vapour [e] at the specific temperature). the august psychrometer comprised standard mercury thermometers (dry-bulb and wet-bulb types). all the thermometers were precisely calibrated at relevant national meteorological centres and, for example, the indication error of the thermometers used at the siberian station of sagastyr did not exceed 0.258c at temperatures above �208c (wood & overland 2006). at most of the stations, the thermometers were placed in instrument shelters designed by wild at a height of 1.5�3 m above ground level (table 1). in the hygrometric method, for example, a saussure-type hair hygrometer was used (fig. 2). according to the programme for the international polar expeditions and recommendations of h. wild (for more details see supplementary file 1), when the air temperature exceeded 0.58c on a wet-bulb thermometer, both a hair hygrometer and a psychrometer were used; at lower temperatures, the relative humidity (rh) was determined using a hair hygrometer only, and the corresponding value of e was calculated with the help of psychrometric charts in relation to the temperature of air read on a drybulb thermometer. according to wild’s experience, hair hygrometers could entirely replace the psychrometer at 08c, as well as at low temperatures if they were properly managed and occasionally verified by comparison with a psychrometer above 08c. he had, moreover, often found that the two instruments remained in perfect accordance between �58c and �158c at the russian stations (proceedings of the meteorological conference at leipzig 1873). at the end of the 19th century, the psychrometric charts of wild�jelinek (1876) were in use. the values of the saturation pressure of water vapour were given here with respect to supercooled water (ewater). the table of saturation pressure with respect to ice (eice) was added in the next edition, in 1911 (anonymous 1912). adjustments to the calculations of e and rh for negative temperatures of the air, made by ekholm (1890) during his experiments table 3 time of execution of meteorological observations at nine polar stations during the first international polar year, 1882�83. station time of observation godthåb local mean time jan mayen kapp thordsen according to göttingen time, correction to local mean time �26 min malye karmakuly local mean time kara sea 1882 j local mean time a s correction to local mean time �23 min n d correction to local mean time �21 min 1883 j f correction to local mean time �22 min m a m j correction to local mean time �26 min j a local mean time sagastyr local mean time point barrow washington mean time, correction to local mean time �5 h 17 min lady franklin bay washington mean time, correction to local mean time �49 min kingua fjord local mean time fig. 2 saussure-type hair hygrometer, manufactured by hottinger & cie, zürich, ca. 1900. image published with kind permission of the technik museum, switzerland. humidity conditions in the arctic during the first ipy p. wyszyński & r. przybylak 4 (page number not for citation purpose) citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23896/0 http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 carried out at the kapp thordsen station during ipy-1, were not applied to psychrometric charts of the norwegian meteorological institute until 1895 (birkeland 1944). the methodology, and its inherent difficulty providing reliable measurements of atmospheric humidity at times of negative air temperature, is best reflected in the reports of the members of the swedish expedition at kapp thordsen (ekholm 1890; see supplementary file 1), and of the dutch expedition covering the kara sea (snellen & ekama 1910; see supplementary file 1). condensation hygrometers, such as alluard or regnault (measuring the temperature at the dew point [td], that is, the temperature at which the water vapour contained in the air becomes saturated), were used together with a chemical approach as control measures for the psychrometric and hygrometric methods. it is interesting to note that the benefits of the measurement of a dew point as an efficient method of determination of atmospheric humidity in the arctic were emphasized as early as at the end of the 19th century: ‘‘yet i believe that, my experiments have demonstrated that regnault’s instrument may be utilised even in the polar lands, and that it is a device which failed to win due appreciation when considering correlations between the indications of a hair hygrometer and those of a thermometer, whilst it may be well applied to correct the indications of the hygrometer regarding changes in the values of temperature’’ (ekama quoted in snellen & ekama 1910: 75). the method has been widely used in meteorological stations in the canadian arctic since 1950 (van wijngaarden & vincent 2005; vincent et al. 2007). the meteorological data used in this paper were sourced from the reports of the polar expeditions organized during ipy-1, published in various years between 1886 and 1910 (table 1). a majority of these reports are available as part of the internet resources of the central library of the us national oceanic and atmospheric administration (noaa; fiolek 2007). photocopies of reports kept at the library of the scott polar research institute in cambridge were also used, and*in the case of a russian expedition to novaya zemlya (malye karmakuly)*a photocopy of the report kept at the library of the russian geographical society of st. petersburg. the data were digitized manually, because this kind of approach guarantees the lowest error rates when acquiring data from antique books and prints (brönnimann et al. 2006). optical character recognition software could not be used because it did not recognize the 19th-century typefaces. manual digitization enabled preliminary verification of incorrect values. moreover, the editors of all the reports which would provide data for this study carried out a quality control to reject any unreliable data. comparing original diurnal means given in the reports with means calculated from the digitized values also eliminated obvious digitization errors. prior to any calculations, the collected data were also subject to a final substantive check using standard methods applied in climatological studies. at point barrow, water vapour pressure was not measured. therefore, this element was calculated on the basis of the air temperature and relative humidity data available in the report, according to the following formula: e ¼ rh �ewater=100; where ewater was taken from psychrometric charts (różdżyński 1995) for the appropriate measured air temperature. mean diurnal values of individual parameters of air humidity were calculated as an actual arithmetic mean, whereas maximum and minimum diurnal values were selected from 24 measurements. as a result of difficulties with the acquisition of measurements in winter, there is a lack of data for some ipy-1 stations. therefore, in the common reference period of ipy-1, and for all stations, this weather element was described only for the 3 months of may, june and july 1883 (tables 4, 6). see supplementary file 2 and 3 for corrected measured water vapour pressure (e) and relative humidity (rh) data, with hourly resolutions. it is important to point out here that although the first digitized meteorological data from ipy-1 were made available on noaa’s website (http://www.arctic.noaa. gov/aro/ipy-1) by wood & overland (2006), it comprised only daily and monthly resolutions (air temperature, atmospheric pressure, direction and wind velocity). krause et al. (2010) have recently developed a complete database for ipy-1, which has been added to the resources of the world data center for marine environmental sciences (http://127.0.0.1:8800/pangavista). the database was compared with the aforementioned noaa and nicolaus copernicus university databases and no significant differences were found. comparison of the historical humidity conditions with current ones has been made using the rh parameter. five of the nine ipy-1 stations for which year-round rh measurements are available were chosen. the second data set includes contemporary rh data (1961�1990) obtained from the historical sites. in four cases (godthåb, jan mayen, malye karmakuly and point barrow) the locations of the observations in the two periods were identical. for the siberian station (sagastyr), the data from the nearest modern station (saggylah ary, situated approximately 80 km from the historical site) have been used. data for modern stations were taken from the p. wyszyński & r. przybylak humidity conditions in the arctic during the first ipy citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/23896/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23896/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23896/0 http://www.arctic.noaa.gov/aro/ipy-1 http://www.arctic.noaa.gov/aro/ipy-1 http://127.0.0.1:8800/pangavista http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 following sources: the danish meteorological institute (cappelen 2012, for godthåb), the norwegian meteorological institute (http://www.eklima.met.no, for jan mayen), the environmental working group arctic meteorology and climate atlas (fetterer & radionov 2000; for malye karmakuly and saggylah ary), and the national climatic data center (http://www.ncdc.noaa.gov, for point barrow). for purposes of comparison with modern rh data, historical rhwater data from low temperatures used in this paper have not been recalculated to rhice. according to the world meteorological organization, modern measurements of rh at temperatures less than 08c are evaluated with respect to water, because: (1) most hygrometers indicate relative humidity with respect to water at all temperatures, and (2) the majority of existing records of rh at temperatures below 08c are expressed on a basis of saturation with respect to water (wmo 2008). however, the reader must be aware that some sources of errors and biases still remain. for example, as a result of the use of different types of instruments and psychrometric charts to determine the rh calculations. results and discussion water vapour pressure (e) generally speaking, the water vapour content of the air in the whole arctic is low because of low temperatures of the air (t). this is a result of both reduced evaporation and a limited water-holding capacity of cold air (przybylak 2003). therefore, the annual course of e in the arctic is very similar to the annual course of t. table 4 basic characteristics of water vapour pressure (e, hpa) at nine stations operating in the arctic during the first international polar year, 1882�83. station parameter a s o n d j f m a m j j a mjj godthåb emax abs 10.9 10.3 6.7 6.3 6.5 5.7 6.4 7.3 6.7 7.7 9.9 12.7 10.4 12.7 e 7.6 6.5 3.9 3.1 2.7 2.4 1.9 3.9 3.5 5.4 6.5 8.4 7.3 6.8 e a min abs 4.8 2.9 1.9 1.1 0.9 0.8 0.7 0.9 1.3 3.5 4.4 5.3 4.1 3.5 jan mayen emax abs 10.7 10.1 9.3 8.4 6.8 6.9 6.9 6.3 6.9 7.3 9.5 10.5 10.5 e 7.2 6.4 6.7 4.8 3.2 3.9 4.3 2.6 4.5 4.1 6.5 7.3 6.0 emin abs 4.1 3.6 3.7 1.3 0.4 0.5 1.1 0.8 1.7 1.7 4.3 5.1 1.7 kapp thordsen b emax abs 8.7 7.9 8.0 6.4 7.6 8.2 9.0 9.7 9.0 e 5.7 4.7 4.2 3.0 3.1 6.0 7.0 7.2 5.4 emin abs 3.3 1.9 0.9 0.5 1.1 3.6 4.9 5.0 1.1 malye karmakuly c emax abs 10.0 8.8 5.7 5.3 5.5 6.1 4.9 6.3 10.1 7.6 10.4 10.5 10.4 e 5.9 3.7 2.5 2.0 1.4 3.0 1.7 3.3 3.6 5.8 7.7 7.0 5.7 emin abs 2.5 0.4 0.4 0.4 0.1 0.5 0.4 0.8 1.2 3.7 5.3 4.3 1.2 kara sead emax abs 6.5 5.7 5.2 5.7 4.4 6.3 6.4 6.8 8.3 8.3 e 2.6 2.2 1.8 2.0 1.9 2.8 2.9 5.3 6.5 4.9 emin abs 0.5 0.5 0.5 0.5 0.5 0.5 0.5 3.6 4.9 0.5 sagastyr emax abs 10.0 4.4 1.3 1.2 0.7 0.5 1.3 2.7 7.2 10.0 13.9 12.5 13.9 e 5.7 2.0 0.6 0.4 0.2 0.2 0.4 1.1 3.1 6.1 8.0 7.1 5.7 emin abs 2.1 0.4 0.2 0.0 0.0 0.0 0.1 0.3 0.8 2.1 6.0 5.2 0.8 point barrowe emax abs 13.7 10.3 7.3 4.8 1.4 2.4 4.1 4.2 2.4 6.0 10.7 12.3 12.9 12.3 e 6.9 5.3 2.1 0.9 0.5 0.5 0.9 0.8 1.0 3.8 5.4 6.4 6.9 5.2 emin abs 3.8 2.8 0.4 0.1 0.1 0.1 0.2 0.1 0.2 0.6 3.2 4.8 3.7 4.8 lady franklin f bay emax abs 7.5 4.3 2.0 2.4 5.2 9.8 7.6 7.1 9.8 e 5.1 2.3 0.9 1.0 2.7 5.1 5.9 5.6 4.6 emin abs 2.8 1.0 0.1 0.1 0.5 2.3 4.5 3.8 0.5 kingua fjordg emax abs 5.9 7.3 8.0 10.1 12.8 10.1 e 2.4 4.5 5.7 7.6 8.3 5.9 emin abs 0.8 2.1 2.9 6.0 6.0 2.1 arctic emax abs 9.3 10.1 10.7 13.9 13.9 e 3.2 3.7 5.8 7.2 5.6 emin abs 0.1 0.5 2.1 4.5 0.5 a emax abs and emin abs are the highest and the lowest observed water vapour pressure, respectively; e is mean monthly water vapour pressure. b august 1882 days 1�14 without data, august 1883 days 24�31 without data. cdecember 1882 days 13�16 without data. d october 1882 days 1�9 without data, november 1882 days 4�7, 13�14, 28�30 without data, december 1882 days 3�4, 18, 21, 24�31 without data; february 1883 days 6, 10�11 without data, march 1883 days 17�22 without data. e august 1883 days 28�31 without data. f observations every 4 h, august 1882 days 1�4 without data, april 1883 days 1�5 without data. goctober 1882 days 1�26. humidity conditions in the arctic during the first ipy p. wyszyński & r. przybylak 6 (page number not for citation purpose) citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 http://www.eklima.met.no http://www.ncdc.noaa.gov http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 the highest monthly mean values of e (table 4) during ipy-1 were observed in the areas of the arctic with the most oceanic type of climate, that is, at godthåb (6.8 hpa) and jan mayen (6.0 hpa). in the north of the canadian arctic, where the climate is more continental, much lower values of e prevailed, as compared with the areas affected by the oceanic climate, for example, 4.6 hpa at lady franklin bay. this kind of spatial distribution of e in the arctic at the time of ipy-1 might have been caused by a meridional inflow of humidity towards the north pole in the atlantic region, connected with north-atlantic cyclonic activity and northerly air currents over the canadian arctic, leading to a reduction of humidity in the area. correlations like this are currently observed (serreze, barry, rehder et al. 1995; serreze, barry & walsh 1995; serreze, rehder, barry et al. 1995; sorteberg & walsh 2008), however it must be noted that the highest water vapour pressure (emax abs) was not observed in the atlantic region (godthåb 12.7 hpa), but in siberia (sagastyr 13.9 hpa). in the annual course of e (table 4, fig. 3), at all the ipy1 stations the highest content of water vapour in the atmosphere was recorded in july or august. in the atlantic arctic, the area of the baffin bay and in alaska, monthly mean values of e in the summer season reached 7�8 hpa. on the other hand, in the north part of the canadian arctic and on the kara sea, these did not exceed 5 or 6 hpa. in the cold season, that is, from november until march, the lowest amount of water vapour was observed. in that period, the mean value of e in the atlantic arctic ranged from 1.4 to 4.8 hpa, whereas in siberia and alaska only 0.2�0.9 hpa. the annual course of absolute values (emax abs and emin abs) was similar to the one for the mean values (e). at most of the stations, emax abs were observed in august or july and the highest of those exceeded 13 hpa. only at one station, lady franklin bay, was the absolute maximum value recorded in june. the lowest values of emin abs were frequent during the winter months. 0 2 4 6 8 10 12 0 2 4 6 8 10 12 (hpa) godthåb (hpa) jan mayen 0 2 4 6 8 10 12 (hpa) kapp thordsen 0 2 4 6 8 10 12 0 2 4 6 8 10 12 (hpa) malye karmakuly (hpa) kara sea 0 2 4 6 8 10 12 (hpa) sagastyr 0 2 4 6 8 10 12 (hpa) point barrow 0 2 4 6 8 10 12 0 2 4 6 8 10 12 (hpa) lady franklin bay (hpa) kingua fjord a s o n d j f m a m j j a a s o n d j f m a m j j a a s o n d j f m a m j j a a s o n d j f m a m j j a a s o n d j f m a m j j a a s o n d j f m a m j j a a s o n d j f m a m j j a a s o n d j f m a m j j a a s o n d j f m a m j j a fig. 3 annual courses of water vapour pressure parameters (hpa) in the arctic in the period of the first international polar year, in 1882�83, according to 11-day running averages. mean daily (black solid line), daily maximum (red dashed line) and minimum (blue dotted line) water vapour pressure are presented. –3 –2 –1 0 1 2 3 gth jm kt mk ks sgt pb lfb kf arctic (hpa) fig. 4 differences in water vapour pressure (hpa) between october and may in the arctic during the first international polar year, in 1882�83. station names are abbreviated as follows: godthåb (gth), jan mayen (jm), kapp thordsen (kt), malye karmakuly (mk), kara sea (ks), sagastyr (sgt), point barrow (pb), lady franklin bay (lfb) and kingua fjord (kf). p. wyszyński & r. przybylak humidity conditions in the arctic during the first ipy citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 the most developed annual courses of e occurred in those regions of the arctic where the climate was the most affected by continentality, that is, in siberia and the canadian arctic, as well as in alaska (fig. 3). at all the analysed stations, the greatest variations in e took place between april and june (positive) and between september and november (negative). in the summer and winter months, the course of e was stable. the annual course of e revealed an evident asymmetry (fig. 4). in the atlantic arctic a higher mean value of water vapour pressure (ca. 1.3 hpa) was recorded in the autumn than in spring, while the opposite pattern occurred in the siberian, canadian, pacific and baffin bay regions (a difference of ca. 1�2 hpa). the greatest day-to-day changes in e in the atlantic arctic occurred in the autumn and winter seasons (table 5, fig. 3). these must have been caused by atmospheric circulation, due to the open atlantic waters that lack an ice-pack in the seasons mentioned above (acsys 2003), which brought in air masses of different temperature and humidity. this is the interpretation assumed by przybylak (1992) for the area of the south spitsbergen in modern times, confirmed for the ipy-1 period by the values of standard deviation of e which amounted to 1.8 and 2.2 hpa at godthåb and malye karmakuly, respectively, in the autumn, and 1.9 hpa at jan mayen in the winter. in the summer, the variations in water vapour pressure were smaller at the atlantic region stations and the standard deviation fell within the range of 0.8�1.2 hpa. in siberia and alaska, the greatest day-to-day variability occurred in the autumn as well. in that season, the standard deviations at sagastyr and point barrow were 2.5 and 2.1 hpa, respectively (table 5). however, the smallest variability at the two stations was not observed in the summer, but in the winter (sd � 0.2 and 0.5 hpa). such stable values of e (fig. 3) resulted from an increased atmospheric pressure which was prevalent in the area at the time (wood & overland 2006; wyszyński 2012; przybylak et al. 2013). this also contributed to a higher frequency of bright days (wyszyński 2012). according to przybylak (1992), this type of weather occurs on spitsbergen during the inflow of intensely chilled air masses with very low water vapour content. the lack of cloud cover also favours reduction of air temperature through the greater loss of heat from surface to space through infrared radiation. therefore, the fluctuations of e were considerably smaller. in the summer seasons, these were comparable to the variations observed in the spring. relative humidity (rh) relative humidity, being the measure of saturation of atmospheric air with water vapour, is the most frequently used parameter to describe the humidity of air in the arctic. in the winter, rh should be calculated with reference to the maximum pressure of water vapour over ice (eice), which is lower than over water (ewater). therefore, the air is oversaturated with water vapour when rh is determined over ice. the state of oversaturation of air with water vapour within the atmospheric boundary layers in the arctic, where there is no condensation, occurs most frequently in the winter at very low temperatures (przybylak 2003). the correlation above was observed and described by malmgren (1926), a scientific assistant to h.u. sverdrup, as he was analysing observation data collected during a norwegian polar expedition in the arctic, on board the maud in 1922�25. as fig. 5 clearly shows, the differences between relative humidity calculated for ice (rhice) and for water (rhwater) are big, exceeding 30%. oversaturation of the air with water vapour in the areas of the arctic where a continental type of climate prevails usually holds on from november until march, so this must be taken into consideration when analysing data for the cold season of the year. table 5 seasonal standard deviations of e (hpa) and rh (%) at nine stations operating in the arctic during the first international polar year, 1882�83. station names are abbreviated as follows: godthåb (gth), jan mayen (jm), kapp thordsen (kt), malye karmakuly (mk), kara sea (ks), sagastyr (sgt), point barrow (pb), lady franklin bay (lfb) and kingua fjord (kf). son djf mam jja station e rh e rh e rh e rh gth 1.8 11.7 1.0 12.8 1.3 9.0 1.0 8.4 jm 1.6 8.9 1.9 5.5 1.5 6.8 1.2 4.6 kt 1.5 9.7 1.6 9.8 1.0 8.4 mk 2.2 10.2 1.5 8.8 1.6 9.9 1.1 10.7 ks 1.4 0.7 1.0 0.5 1.4 7.1 0.8 3.5 sgt 2.5 4.2 0.2 2.8 1.4 4.6 1.4 4.9 pb 2.1 5.5 0.5 5.8 1.7 5.8 1.5 3.6 lfb 0.9 10.6 1.1 14.9 0.9 5.8 kf 1.4 8.5 humidity conditions in the arctic during the first ipy p. wyszyński & r. przybylak 8 (page number not for citation purpose) citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 during ipy-1 the mean monthly values of rh in the arctic (calculated for measurements taken over water) for the common reference period of may�july 1883 were high and exceeded 80% (table 6). the highest mean rh of all the stations considered during ipy-1 was recorded in siberia (sagastyr 91.8%), whereas the lowest mean was obtained on spitsbergen (kapp thordsen 79.8%). a high rh (90%) was also observed in the area of the norwegian sea (jan mayen), characterized by the greatest influence of climate oceanity. the annual courses of rh (table 6, fig. 6) in the areas of the arctic which were affected by frequent cyclonic activity, that is, in the norwegian arctic (jan mayen, kapp thordsen), on the barents and kara seas (malye karmakuly, kara sea) and on the coast of baffin bay (godthåb, kingua fjord), were rather balanced, with individual values falling within the range of 75�90%. such annual courses of rh are observed in the norwegian arctic today, as well (araźny 2003). moreover, monthly mean diurnal amplitudes of rh (i.e., the differences between rhmax and rhmin; see fig. 6) were relatively steady and amounted to 15�25% in specific months. more distinct changes in the annual courses of rh were observed in siberia (sagastyr) and alaska (point barrow), where the annual course of rh resembled the annual course of the air temperature (see przybylak et al. 2010). the highest monthly mean of rh at those stations was observed in july or august (�90%), whereas the lowest values were recorded in february, march or april. monthly mean amplitudes of the diurnal values of rh in siberia and alaska (fig. 6) reached ca. 15% in the late spring, summer and early autumn when the effects of solar radiation were the greatest, but only 5�6% in the winter. in the north part of the canadian arctic (lady franklin bay), the highest mean monthly diurnal amplitudes of rh (fig. 6) were observed in october (24%), april (50%) and may (24%). in the summer months, on the other hand, the variability of rh did not exceed 12�16%. in the autumn and spring seasons, at the lady franklin bay the highest day-to-day variability in rh was noted (sd �10.6% and 14.9%). such high mean monthly diurnal amplitudes (particularly in april) and day-to-day changes in rh at the station seem hard to explain. these should instead be associated with difficulties faced during hygrometric measurements in the cold seasons of the year. naturally, the observations continued from november until march, yet the researchers refrained from publishing the results in reports due to their uncertainty as to the reliability of the data; the report of the american expedition (greely 1886), for example, contains only fragmentary measurements of rh for the cold season months. during ipy-1 there were situations in the arctic where the relative humidity was found to decrease substantially (fig. 7). on 11 january 1883, rh at godthåb remained at a level of 90�100% during the first half of the overcast day (10, stratus) with air masses flowing from the south-west sector. in the evening though, the air started to come from the east, which resulted in a decrease in the air temperature of 2�38c and a decrease in the amount of cloud cover to 0�2 (mainly cirrostratus). a katabatic flow of dry air (e values were 1.0�1.5 hpa) and cold greenland air brought in a drop in relative humidity to ca. 45% within only a few hours. such dramatic decreases of rh resulting from the effects of katabatic flows are also observable today (renfrew & anderson 2002). the situation continued until the afternoon of 13 january 1883, only disrupted by an inflow of warmer and more humid air from the south-west which lasted for a few hours on 12 january. eventually, on 14 january the direction of the wind changed back to southerly, bringing warm and humid air (rh �80%) from over the atlantic ocean, which made the sky overcast. the data gathered by the dutch expedition on the kara sea provided the basis for the conclusion that the air there was permanently saturated with water vapour (rhice �100%) in the period from november 1882 until march 1883 (see fig. 5). this assumption was supported by the values of rhmin abs, which did not fall below 96% in the period concerned, and the mean values of rh, which were 100% (table 6, fig. 6). the observers considered the saturation point to be when the hair of the hygrometer fig. 5 mean annual course of relative humidity (rh, %), in the arctic ocean. source: malmgren (1926). rw denotes rh with respect to the water; ri denotes rh with respect to the ice. p. wyszyński & r. przybylak humidity conditions in the arctic during the first ipy citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 was covered by hoar frost (for more details see supplementary file 1). according to malmgren (1926), hoar frost is generally formed when rhice is greater than 100% but never when rhice is below 100%. moreover, the probability of hoar frost building increases when the wind velocity is low (up to 2 ms �1 ). such winds often occurred on the ice-pack of the kara sea during the ipy-1 period. their frequency from november 1882 to march 1883 was 30�50% (wyszyński 2012). throughout the year, days with the maximum saturation of air with water vapour occurred at nearly all the ipy-1 stations (with the exception of sagastyr and point barrow) (table 6). on the other hand, at the sagastyr station in siberia the air never reached the level of complete saturation from november until march (the values of rhmax abs were lower than 100%). at point barrow, the saturation deficit persisted year-round. day-to-day variability of rh in the areas of the atlantic arctic and alaska influenced by intense cyclonic activity was the greatest in the cold time of the year, and the lowest in the summer. in the area of the kara sea, the waters of which were frozen over in the early spring (hovgaard 1884), resulting in a unification of the geographical environment, the smallest day-to-day variability in rh was observed in the autumn and winter seasons (sd �0.5�0.7%). when the sea ice was melting in the spring, on the other hand, the day-to-day changes were considerably greater (sd �9.9%). in the area where the table 6 basic characteristics of relative humidity (rh, %) at nine stations operating in the arctic during the first international polar year, 1882�83. station parameter a s o n d j f m a m j j a mjj godthåb rhmax abs 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 rh 89.8 85.9 78.5 74.5 75.7 80.8 92.8 85.0 84.1 88.0 87.5 88.8 84.5 88.1 rhamin abs 42.0 32.0 43.0 38.0 33.0 12.0 54.0 26.0 40.0 51.0 52.0 33.0 30.0 33.0 jan mayen rhmax abs 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 rh 93.0 89.7 92.5 85.2 91.2 91.8 88.8 82.7 86.0 86.8 92.5 91.4 90.2 rhmin abs 57.0 60.0 49.0 46.0 64.0 71.0 29.0 56.0 58.0 53.0 59.0 69.0 53.0 kapp thordsenb rhmax abs 96.0 100.0 100.0 97.0 97.0 100.0 100.0 100.0 100.0 rh 77.3 82.2 83.6 72.9 70.3 85.5 83.6 78.6 79.8 rhmin abs 57.0 56.0 50.0 49.0 38.0 51.0 51.0 41.0 38.0 malye karmakuly c rhmax abs 100.0 100.0 100.0 100.0 100.0 100.0 100.0 99.0 99.0 99.0 99.0 100.0 99.0 rh 95.2 86.8 82.1 85.9 81.7 90.1 79.2 80.4 80.1 87.3 84.6 78.3 84.0 rhmin abs 71.0 50.0 31.0 56.0 46.0 62.0 48.0 36.0 48.0 49.0 49.0 31.0 48.0 kara sea d rhmax abs 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 rh 99.5 99.9 99.8 99.6 100.0 98.7 96.6 85.5 92.0 96.6 91.4 rhmin abs 88.0 98.0 96.0 97.0 100.0 88.0 81.0 58.0 77.0 85.0 58.0 sagastyr rhmax abs 100.0 100.0 98.0 90.0 89.0 89.0 92.0 100.0 100.0 100.0 100.0 100.0 100.0 rh 89.0 89.6 87.3 81.9 83.2 80.7 83.6 86.8 91.4 91.9 92.2 90.6 91.8 rhmin abs 56.0 78.0 79.0 71.0 79.0 76.0 80.0 80.0 59.0 64.0 63.0 58.0 59.0 point barrow e rhmax abs 97.0 97.0 95.0 94.0 97.0 98.0 97.0 93.0 86.0 98.0 97.0 98.0 97.0 98.0 rh 86.5 87.9 85.2 84.1 87.1 85.1 80.1 76.5 77.0 85.3 87.6 87.8 90.3 86.9 rhmin abs 57.0 60.0 75.0 62.0 80.0 67.0 68.0 67.0 66.0 73.0 74.0 70.0 67.0 70.0 lady franklin bayf rhmax abs 97.0 100.0 100.0 100.0 100.0 99.0 95.0 100.0 rh 80.0 93.7 83.0 67.4 87.9 80.1 78.4 82.1 rhmin abs 54.0 25.0 19.0 9.0 32.0 58.0 56.0 32.0 kingua fjord g rhmax abs 100.0 98.0 100.0 100.0 100.0 100.0 rh 76.6 78.4 78.8 82.5 81.6 79.9 rhmin abs 50.0 44.0 32.0 54.0 46.0 32.0 rhmax abs 100.0 100.0 100.0 100.0 100.0 arctic rh 86.2 83.7 87.0 87.3 86.0 rhmin abs 19.0 32.0 32.0 33.0 32.0 a rhmax abs, rhmin abs are the highest and the lowest observed relative humidity, rh is mean monthly relative humidity. b august 1882 days 1�14 without data, august 1883 days 24�31 without data. c december 1882 days 13�16 without data. doctober 1882 days 1�9 without data, november 1882 days 4�8, 12�14 without data, december 1882 days 21, 24�31 without data, january 1883 days 16�31, march 1883 days 17�22 without data. e august 1883 days 28�31 without data. fobservations every 4 h, august 1882 days 1�4 without data, november 1882 days 1�2, 8�9, 13, 15, 18�21, 24�27, 29�30 without data, october 1882 days 5, 19 without data, april 1883 days 1�3, 17, 24, 27�28 without data, may 1883 days 9, 23�24 without data. g october 1882 days 1�26. humidity conditions in the arctic during the first ipy p. wyszyński & r. przybylak 10 (page number not for citation purpose) citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23896/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23896/0 http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 continentality affected the climate the most (sagastyr), the variability in rh followed a different day-to-day pattern than in the areas characterized by the maritime climate. comparison with present-day conditions the mean values of rh in the ipy-1 period (september 1882 to july 1883) for five of the nine stations analysed were higher than today’s values, by 2.4�5.6%, because the air temperature was colder at that time than today, by 1.0�1.58c on average (for more details see przybylak et al. 2010). values higher than those currently prevailing were noted mainly in the norwegian sea and barents sea regions (5.6 and 5.0%, respectively), whereas in the continental part of the arctic (the siberian region represented by sagastyr station), the positive differences were smaller and their variability around the modern long-term (1961�1990) monthly means were the most stable (table 7). because the content of the water vapour pressure in the arctic is generally small, so the changes in rh are mainly the function, as mentioned above, of air temperature changes. the highest positive anomalies of rh, exceeding �2 sds in some months (fig. 8) were noted in the atlantic arctic. these noticeable differences were the result of atmospheric circulations carrying, in the vicinity of the analysed stations, air masses characterized by different thermal and humidity conditions. for example, in february of 1883 in godthåb, the greatest noted positive anomaly of rh occurred while the station was under the influence of cold air masses (table viii in przybylak et al. 2010). on the other hand, in february of 1883 in malye karmakuly, the large positive rh anomaly (13.4%) there was connected with the inflow of warmer but very wet air masses (fig. 3) from the south�ssw direction (wyszyński 2012). large positive anomalies (by 10�13%) were also noted at point barrow in winter, which was characterized by strong negative thermal anomalies in comparison with present-day conditions. such variation in rh is also observable today, indicated by the high range of 92 sds in the cold half of the year (fig. 8). despite the exemplary cases described above, most of the observed changes between historical and modern rh values are not significant. the majority of historical daily rh values lie between a distance of �2 sds from the present long-term (1961�1990) monthly means (fig. 8). conclusions meteorological data gathered for the arctic during ipy-1 are the best in terms of coverage, quality, resolution and other characteristics out of all the early instrumental data 0 10 a s o n d f m a m j j aj a s o n d f m a m j j aj a s o n d f m a m j j aj a s o n d f m a m j j aj a s o n d f m a m j j aj a s o n d f m a m j j aj a s o n d f m a m j j aj a s o n d f m a m j j aj a s o n d f m a m j j aj 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 100 (%) godthåb 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 (%) jan mayen (%) kapp thordsen 90 0 10 20 30 40 50 60 70 80 100 90 0 10 20 30 40 50 60 70 80 100 90 (%) malye karmakuly (%) kara sea sagastyr(%) 0 10 20 30 40 50 60 70 80 90 100 (%) point barrow 0 10 20 30 40 50 60 70 80 90 100 (%) lady franklin bay 0 10 20 30 40 50 60 70 80 90 100 (%) kingua fjord fig. 6 annual courses of relative humidity parameters (%) in the arctic in the period of the first international polar year, in 1882�83, according to 11day running averages. mean daily (black solid line), daily maximum (red dashed line) and minimum (blue dotted line) relative humidity are presented. p. wyszyński & r. przybylak humidity conditions in the arctic during the first ipy citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 –11 –10 –9 –8 –7 –6 –5 –4 –3 –2 –1 0 01 07 13 19 01 07 13 19 01 07 13 19 01 07 13 19 01 t e 0 1 2 3 4 5 6 7 8 9 10 0 30 60 90 120 150 180 210 240 270 300 330 360 dir. v c 40 45 50 55 60 65 70 75 80 85 90 95 100 rh (hpa) (%) 11/01/883 12/01/1883 13/01/1883 14/01/1883 [h] (°c) fig. 7 courses of relative humidity (rh, %), water vapour pressure (e, hpa), air temperature (t, 8c), wind directions (dir. v, 0�3608) and cloud cover (c, 0�10) in godthåb on 11�14 january 1883. table 7 relative humidity differences (%) between mean monthly values from the first international polar year, 1882�83, and the modern period (1961�1990). positive values are shown in boldface. stationa a s o n d j f m a m j j a sep-jul godthåbb 3.0 3.5 0.9 �1.8 �1.0 3.5 14.0 4.2 3.2 3.7 3.1 2.3 �2.3 3.2 jan mayen c 6.9 6.9 10.4 5.4 9.5 8.6 6.3 �0.4 3.7 2.2 5.9 3.3 5.6 malye karmakulyd 10.8 5.1 2.5 6.6 3.8 13.4 1.1 4.2 0.5 4.0 2.8 �5.1 5.0 sagastyr e 1.0 2.5 4.3 �0.3 2.5 �0.2 2.0 3.3 4.8 1.8 4.2 1.8 2.4 point barrowf �4.1 �2.3 0.2 5.3 13.5 12.8 10.5 6.1 1.1 �1.0 �0.6 0.2 �0.3 4.1 a for purposes of comparison, data from the following modern stations located at the same sites, or nearest to the historical stations, have been used. bnuuk. c jan mayen. d malye karmakuly. esagyllah ary. f point barrow. humidity conditions in the arctic during the first ipy p. wyszyński & r. przybylak 12 (page number not for citation purpose) citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 for the area. research carried out during the ipy-1 scientific expeditions brought a significant contribution to the development of hygrometry in polar regions at the end of the 19th century. the spatial distribution of atmospheric water vapour in the arctic during ipy-1, in the common observational period (may�july 1883), was similar to the present distribution. the highest monthly means of e for the common reference period of may�july 1883 were determined for the area of baffin bay (6.8 hpa) and the atlantic ocean (6.0 hpa), where the oceanic influences were the greatest. in the north part of the canadian arctic, where the continental type of climate prevails, lower values of water vapour pressure predominated (4.6 hpa) in comparison with the areas subject to the oceanic climate. in the annual course, the highest values of e during ipy1 were noted in july and august, while the lowest were in the cold half of the year. the annual course of e is evidently asymmetrical. in the norwegian arctic, more water vapour (by about 1.3 hpa) was in the air in autumn than in spring, while the opposite relation occurred in siberia and the american arctic. monthly means of rh were high, and most often exceeded 80%. the highest mean of rh of all the ipy-1 stations was observed in siberia (91.8%), and the lowest on spitsbergen (79.8%). a high rh was found in the area of the norwegian sea (90%), with the most oceanic climate. over the year, the course of relative humidity in the areas of the arctic that are subject to cyclonic activity remained fairly constant, that is, in the norwegian arctic, the basin of the barents and kara seas, as well as in baffin bay, with values within the range of 75�90%. this kind of annual course of rh in the norwegian arctic is also observed at present (araźny 2003). in comparison to present-day conditions, mean rh values in the ipy-1 period (september 1882 to july 1883) were higher by 2.4�5.6%. the greatest differences mainly occurred in the atlantic arctic, whereas in the continental part of the arctic the positive differences were smaller and more stable (table 7). most of the observed changes 50 60 70 80 90 100 (%) 50 60 70 80 90 100 (%) jan mayen 50 60 70 80 90 100 (%) malye karmakuly 50 60 70 80 90 100 (%) sagastyr 50 60 70 80 90 100 (%) point barrow godthåb a s o n d j f m a m j j a a s o n d j f m a m j j a a s o n d j f m a m j j a a s o n d j f m a m j j a a s o n d j f m a m j j a fig. 8 annual courses of historical international polar year 1882�83 (solid line) and modern (1961�1990, dashed line) relative humidity (rh, %). standard deviations (92 sd, dotted lines) have been calculated on the basis of the present data. international polar year courses are based on daily means, modern and sds based on monthly means. data from the modern stations located nearest the historical stations have been used (see table 7). p. wyszyński & r. przybylak humidity conditions in the arctic during the first ipy citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 13 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 between historical and modern rh values are not significant. the majority of historical daily rh values lie between a distance of �2 sds from the present long-term (1961�1990) monthly means. acknowledgements the research in this article was supported by the variability of the russian arctic and subarctic climate in the last three hundred years grant, funded by the national science centre (decision no. dec-2012/07/b/st10/04002) and by the polish�norwegian fund as part of the arctic climate system study of ocean, sea ice and glaciers interactions in the svalbard area project (awake-2). we would also like to thank dr zsuzsanna vı́zi for assistance in calculating the water vapour pressure for point barrow in the fortran programming language. references acsys (arctic climate system study). 2003 acsys historical ice chart archive (1553�2002). iacpo informal report no. 8. tromsø, norway: arctic climate system study. allan r., brohan p., compo g.p., stone r., luterbacher j. & brönnimann s. 2011. the international atmospheric circulation reconstructions over the earth (acre) initiative. bulletin of the american meteorological society 92, 1421�1425. anonymous. 1912. jelinek’s psychrometer-tafeln. (jelinek’s psychrometric charts.) our book shelf. nature 89, p. 5. araźny a. 2003. przebieg roczny wilgotności względnej w arktyce norweskiej w okresie 1971�2000. (annual course of relative air humidity in the norwegian arctic from 1971 to 2000.) problemy klimatologii polarnej 13, 107�115. barr s. & lüdecke c. (eds.) 2010. the history of the international polar years (ipys). london: springer. barr w. 2008. the expeditions of the first international polar year, 1882�83. 2nd edn. calgary: arctic institute of north america. birkeland b.j. 1944. mittel und extreme der feuchtigkeit in norwegen. (means and extremes of humidity in norway.) geofysiske publikasjoner 15(1). oslo: norwegian academy of science. brohan p., ward c., willetts g., wilkinson c., allan r. & wheeler d. 2010. arctic marine climate of the early nineteenth century. climate of the past 6, 315�324. brönnimann s., annis j., dann w., ewen t., grant a.n., griesser t., krähenmann s., mohr c., scherer m. & vogler c. 2006. a guide for digitising manuscript climate data. climate of the past 2, 137�144. cappelen j. (ed.) 2012. weather and climate data from greenland 1958�2011. observation data with description. technical report 12�15. copenhagen: danish meteorological institute. ekholm n.g. 1890. observations faites au cap thorsden, spitzberg, par l’expédition suédoise. tome i: 3. observations météorogiques. (observations made at cape thorsden, spitsbergen, by a swedish expedition. vol. i: 3. meteorological observations.) stockholm: royal printing office. fetterer f. & radionov v. (eds) 2000. environmental working group arctic meteorology and climate atlas. ver. 1. cd-rom. boulder: national snow and ice data center. fiolek a. 2007. international polar year 2007�2008. resources on polar research in the noaa central library network. a selected bibliography. silver spring, md: u.s. department of commerce national oceanic and atmospheric administration, national environmental satellite, data, and information service, national oceanographic data center, noaa central library. golcman m.i. 1939. o izmereniah vlaźnosti vozduha v niskih temperaturah. (about measurements of water vapour in law temperatures.) problemy arktiki 1, 39�53. golcman m.i. 1949. problemy izmerenij vlažnosti vozduha w arktike. (difficulties in measurements of water vapour in the arctic.) problemy arktiki 3, 42�71. greely a.w. 1886. report on the proceedings of the united states expedition to lady franklin bay, grinnell land vol. i�ii. washington, dc: government printing office. hovgaard a.p. 1884. die eiszustände im karischen meere. (ice conditions in the kara sea.). mitteilungen aus justus perthes’ geographischer anstalt 30, 253�259. jelinek c. 1876. psychrometertafeln für das hunderttheilige thermometer nach dr. h. wild’s tafeln bearbeitet von dr. c. jelinek etc. zweite auflage. (psychrometric charts for the hundredth scale thermometer according to dr. h. wild’s tables edited by dr. c. jelinek etc.) 2nd edn. vienna: engelmann. kay p.a. 1995. an early nineteenth century meteorological register from the eastern canadian arctic. polar record 31, 335�342. klimenko v.v. 2008. reconstruction of climate in the russian arctic over the last 600 years based on documentary evidence. doklady earth sciences 418, 95�98. klimenko v.v. 2010. a composite reconstruction of the european part of the russian arctic climate back to a.d. 1435. in r. przybylak et al. (eds.): the polish climate in the european context: an historical overview. pp. 295�326. new york: springer. klimenko v.v. & astrina n.a. 2006. documentary evidence of strong climate fluctuations of the russian arctic in the xv�xxth centuries. history and modernity 1, 179�217. klingbjer p. & moberg a. 2003. a composite monthly temperature record from tornedalen in northern sweden, 1802�2002. international journal of climatology 23, 1465�1494. koch j.p. & wegener a. 1930. wissenschaftliche ergebnise der danische expedition nach dronning louises land und über das inlandeis, von nordgrönland 1912�1913. (scientific results of the danish expedition to dronning louise land and concerning the inland ice of north greenland in 1912�1913.) meddelelser om grönland 75. copenhagen: commission for scientific research in greenland. krause r., grobe h. & sieger r. 2010. international polar year 1882�83*the digitized meteorological data legacy. wdc-mare humidity conditions in the arctic during the first ipy p. wyszyński & r. przybylak 14 (page number not for citation purpose) citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 reports 8. bremerhaven: alfred wegener institute for polar and marine research. lenz r. (ed.) 1886a. beobachtungen der russischen polarstation an der lenamündung. expedition der kaiserl. russischen geographischen gesellschaft. ii. theil. meteorologische beobachtungen bearbeitet von a. eigner. (observations of the russian polar station on the lena estuary. expedition of the imperial russian geographical society. part ii. meteorological observations edited by a. eigner.) st. petersburg: imperial russian geographical society. lenz r. (ed.) 1886b. beobachtungen der russischen polarstation auf nowaya semlja. expedition der kaiserl. russischen geographischen gesellschaft. ii. theil. meteorologische beobachtungen bearbeitet von k. andrejeff. (observations of the russian polar station on novaya zemlya. expedition of the imperial russian geographical society. part ii. meteorological observations edited by k. andreyev.) st. petersburg: imperial russian geographical society. loewe f. 1935. das klima des grönlandischen inlandeises. (the climate of the greenland’s inland ice.) in w. köppen & r. geiger (eds.): handbuch der klimatologie. bd. ii. teil k. klima des kanadischen archipels und grönlands. (handbook of climatology. vol. ii. part k. the climate of the canadian archipelago and greenland.) berlin: verlag von gebrüde. lüdecke c. 2004. the first international polar year (1882� 1883): a big science experiment with small science equipment. history of meteorology 1, 55�64. lüdecke c. 2005. east meets west: meteorological interests of the moravians in greenland and labrador since the 18th century. history of meteorology 2, 123�132. malmgren f. 1926. studies of humidity and hoar-frost over the arctic ocean. geofysiske publikasjoner 4(6), 2�20. neumayer g.b. & börgen c.n.j. 1886. die beobachtungsergebnisse der deutschen stationen. band i. kingua-fjord und die meteorologischen stationen ii. ordnung in labrador: hebron, okak, nain, zoar, hoffenthal, rama, sowie die magnetischen observationen in breslau und göttingen. (the observational results of the german stations vol. i. kingua fjord and the meteorological stations of the second order in labrador: hebron, okak, nain, zoar, hoffensthal, rama, and the magnetic observations in breslau and göttingen.) berlin: verlag von a. asher & co. paulsen a.f.w. 1886. observations internationales polaires 1882� 1883. expédition danoise. observations faits à godthaab. tome ii. i météorologie. (observations from the international polar year of 1882�1883. danish expedition. observations made in godthaab. vol. ii. i meteorology.) copenhagen: meteorological institute of denmark. polyakov i.v., bekryaev r.v., alekseev g.v., bhatt u.s., colony r.l., johnson m.a., maskshtas a.p. & walsh d. 2003. variability and trends of air temperature and pressure in the maritime arctic, 1875�2000. journal of climate 16, 2067�2077. proceedings of the meteorological conference at leipzig. 1873. report of the proceedings of the meteorological conference at leipzig. protocols and appendices. translated from the official report. london: meteorological office. przybylak r. 1992. stosunki termiczno-wilgotnościowe na tle warunków cyrkulacyjnych w hornsundzie (spitsbergen) w okresie 1978�1983. (the thermic and humidity relations against a background of the circulations conditions in hornsund [spitsbergen] in the period 1978�1983.) dokumentacja geograficzna 2. warsaw: institute of geography, polish academy of sciences. przybylak r. 2000. air temperature in the canadian arctic in the mid-nineteenth century based on data from expeditions. prace geograficzne 107, 251�258. przybylak r. 2003. the climate of the arctic. dordrecht: kluwer academic publishers. przybylak r. 2004. temperatura powietrza w arktyce w okresie pierwszego międzynarodowego roku polarnego 1882/1883. (air temperature in the arctic in the period of first international polar year 1882/83.) in a. styszyńska & a. marsz (eds.): polish polar studies, 30th international polar symposium, gdynia. pp. 307�320. gdynia: institute of meteorology and oceanography. przybylak r. 2007. recent air-temperature changes in the arctic. annals of glaciology 46, 316�324. przybylak r. & dzierżawski j. 2004. stosunki termiczne i wilgotnościowe w zatoce treurenberg i na masywie olimp (ne spitsbergen) w okresie od 1 viii 1899*15 viii 1900. (thermal and humidity relations in treurenberg bay and massif olimp [ne spitsbergen] from 1 august 1899 to 15 august 1900.) problemy klimatologii polarnej 14, 133�147. przybylak r. & vı́zi z. 2004. sources of meteorological data for the canadian arctic and alaska from 1819 to 1859 and their usefulness for climate studies. in: fourth seminar for homogenization and quality control in climatological databases. pp. 151�165. geneva: world meteorological organization. przybylak r. & vı́zi z. 2005. air temperature changes in the canadian arctic from the early instrumental period to modern times. international journal of climatology 25, 1507�1522. przybylak r., vı́zi z. & wyszyński p. 2010. air temperature changes in the arctic from 1801 to 1920. international journal of climatology 30, 791�812. przybylak r., wyszyński p., vı́zi z. & jankowska j. 2013. atmospheric pressure changes in the arctic from 1801 to 1920. international journal of climatology 33, 1730�1760. ray p.h. 1885. report of the international polar expedition to point barrow, alaska. washington, dc: government printing office. renfrew i.a. & anderson p.s. 2002. the surface climatology of an ordinary katabatic wind regime in coats land, antarctica. tellus a 54, 463�484. różdżyński k. 1995. miernictwo meteorologiczne. tom 1. (meteorological metrology. vol. 1.) warsaw: institute of meteorology and water management. serreze m.c., barrett a.p. & stroeve j. 2012. recent changes in tropospheric water vapor over the arctic as assessed from radiosondes and atmospheric reanalyses. journal of geophysical research*atmospheres 117, d10104, doi: 10.1029/ 2011jd017421. p. wyszyński & r. przybylak humidity conditions in the arctic during the first ipy citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 15 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 serreze m.c. & barry r.g. 2011. processes and impacts of arctic amplification: a research synthesis. global and planetary change 77, 85�96. serreze m.c., barry r.g., rehder m.c. & walsh j.e. 1995. variability in atmospheric circulation and moisture over the arctic. philosophical transactions of the royal society a 352, 215�225. serreze m.c., barry r.g. & walsh j.e. 1995. atmospheric water vapor characteristics at 708n. journal of climate 8, 719�731. serreze m.c., rehder m.c., barry r.g., kahl j.d. & zaitseva n.a. 1995. the distribution and transport of atmospheric water vapour over the arctic basin. international journal of climatology 15, 709�727. snellen m. & ekama h. 1910. rapport sur l’expédition néerlandaise qui a hiverné dans la mer de kara en 1882/1883. (report on the dutch expedition that wintered in the kara sea in 1882/1883.) utrecht: j. van boekhoven. sorteberg a. & walsh j.e. 2008. seasonal cyclone variability at 708n and its impact on moisture transport into the arctic. tellus a 60, 570�586. sverdrup h.u. 1935. übersicht über das klima des polarmeers und das kanadischen archipels. (overview of the climate of the arctic ocean and the canadian archipelago.) in w. köppen & r. geiger (eds.): handbuch der klimatologie. bd. 2. teil k. klima des kanadischen archipels und grönlands. (handbook of climatology. vol ii. part k. the climate of the canadian archipelago and greenland.) pp. k3�k30. berlin: verlag von gebrüder borntraeger. symon c., arris l. & heal b. (eds.) 2005. arctic climate impact assessment. cambridge: cambridge university press. trešnikov a.f. (ed.) 1985. atlas arktiki. (atlas of the arctic.) moscow: principal administration of geodesy and cartography. van wijngaarden w.a. & vincent l.a. 2005. examination of discontinuities in hourly surface relative humidity in canada during 1953�2003. journal of geophysical research* atmospheres 110, d22102, doi: 10.1029/2005jd005925. vincent l.a., van wijngaarden w.a. & hopkinson r. 2007. surface temperature and humidity trends in canada for 1953�2005. journal of climate 20, 5100�5113. vinther b.m., andersen k.k., jones p.d., briffa k.r. & cappelen j. 2006. extending greenland temperature records into the late eighteenth century. journal of geophysical research*atmospheres 111, d11105, doi: 10.1029/2005 jd006810. vı́zi z. 2008. variability of the american arctic climate in the 19th century. phd thesis, nicolaus copernicus university. von wohlgemuth e.e. 1886. die österreichische polarstation jan mayen: ausgerüstet durch seine escellenz graf hanns wilczek, beobachtungs-ergebnisse. (the austrian polar station of jan mayen: equipped by his excellency count hanns wilczek; observational results.) vienna: imperial academy of sciences. wild h. (ed.) 1882. communications from the international polar commission. st. petersburg: imperial academy of science. wilkinson c., woodruff s.d., brohan p., claesson s., freeman e., koek f., lubker s.j., marzin c. & wheeler d. 2011. recovery of logbooks and international marine data: the reclaim project. international journal of climatology 31, 968�979. willett k.m., jones p.d., gillett n.p. & thorne p.w. 2008. recent changes in surface humidity: development of the hadcruh dataset. journal of climate 21, 5364�5383. wmo (world meteorological organization) 2008. guide to meteorological instruments and methods of observation. wmo-no. 8. 7th edn. geneva: world meteorological organization. wood k.r. & overland j.e. 2003. accounts from 19th-century canadian arctic explorers’ logs reflect present climate conditions. eos, transactions of the american geophysical union, 84, 410, 412. wood k.r. & overland j.e. 2006. climate lessons from the first international polar year. bulletin of the american meteorological society 87, 1685�1697. wood k.r., overland j.e., jónsson t. & smoliak b.v. 2010. air temperature variations on the atlantic�arctic boundary since 1802. geophysical research letters 37, l17708, doi: 10.1029/2010gl044176. wyszyński p. 2012. warunki meteorologiczne w arktyce w czasie trwania pierwszego międzynarodowego roku polarnego 1882/ 1883 i ich porównanie z warunkami wspólczesnymi. (meteorological conditions in the arctic in the period of the first international polar year 1882/83 and their comparison with present conditions.) phd thesis, nicolaus copernicus university. humidity conditions in the arctic during the first ipy p. wyszyński & r. przybylak 16 (page number not for citation purpose) citation: polar research 2014, 33, 23896, http://dx.doi.org/10.3402/polar.v33.23896 http://www.polarresearch.net/index.php/polar/article/view/23896 http://dx.doi.org/10.3402/polar.v33.23896 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <feff0055007300650020006500730074006100730020006f007000630069006f006e00650073002000700061007200610020007200650061006c0069007a0061007200200075006e00200069006e0066006f0072006d006500200073006f0062007200650020006c006100200063006f006d007000610074006900620069006c006900640061006400200063006f006e0020005000440046002f0058002d003300200079002000670065006e006500720061007200200064006f00630075006d0065006e0074006f007300200050004400460020007300f3006c006f00200073006900200073006f006e00200063006f006d00700061007400690062006c00650073002e0020005000440046002f005800200065007300200075006e002000650073007400e1006e006400610072002000490053004f0020007000610072006100200065006c00200069006e00740065007200630061006d00620069006f00200064006500200063006f006e00740065006e00690064006f00200067007200e1006600690063006f002e002000500061007200610020006f006200740065006e006500720020006d00e1007300200069006e0066006f0072006d00610063006900f3006e00200061006300650072006300610020006400650020006300f3006d006f00200063007200650061007200200064006f00630075006d0065006e0074006f0073002000500044004600200063006f006d00700061007400690062006c0065007300200063006f006e0020005000440046002f0058002d0033002c00200063006f006e00730075006c007400650020006c006100200047007500ed0061002000640065006c0020007500730075006100720069006f0020006400650020004100630072006f006200610074002e0020004c006f007300200064006f00630075006d0065006e0074006f00730020005000440046002000730065002000700075006500640065006e00200061006200720069007200200063006f006e0020004100630072006f00620061007400200079002000520065006100640065007200200034002e003000200079002000760065007200730069006f006e0065007300200070006f00730074006500720069006f007200650073002e> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice no job name melt pond formation and temporal evolution at the drifting station tara during summer 2007por_161 311..321 paula sankelo,1 jari haapala,2 istván heiler2 & eero rinne3 1 department of geographical and earth sciences, university of glasgow, gregory building, lilybank gardens, glasgow, g12 8qq, uk 2 finnish meteorological institute, po box 503, fi-00101 helsinki, finland 3 school of geosciences, university of edinburgh, drummond street, edinburgh, eh8 9xp, uk abstract melt pond coverage of sea ice in the high arctic was observed for a period of 28 days: from 24 june to 21 july 2007. pond fractions were computed from digital photographs automatically obtained with a camera and computer unit mounted in the mast of the drifting polar schooner tara. the area visible in the series of images corresponds to approximately 6400 m2 on the ice. by applying iterative image classification methods, the images were partitioned into melt ponds and other surface types, such as ice or snow. the percentage of melt ponds could be calculated for 22 out of 28 days. six days were omitted from the analysis because of weather conditions causing poor visibility. melt pond coverage was seen to rise rapidly shortly after the melt ponds started forming: between 24 and 30 june 2007 the pond fraction increased from 3 to 14%. after the first rapid growth period, the pond fraction increased more gradually, reaching 15% at the end of the data collection period (21 july 2007). estimated with additional data, the maximum melt pond coverage was reached in midaugust, and totalled 32–42%. melt onset date and the initial rapid melt pond growth agree well with previous research, but the areal pond coverage appears surprisingly high for the latitude (88°n). direct comparison with previously observed melt pond coverage is rendered difficult by scarce observations of pond coverage sufficiently high up in the arctic. keywords albedo; melt pond; sea ice. correspondence paula sankelo, department of geographical and earth sciences, university of glasgow, gregory building, lilybank gardens, glasgow, g12 8qq, uk. e-mail: paula.sankelo@ges.gla.ac.uk doi:10.1111/j.1751-8369.2010.00161.x sea-ice albedo is one of the key parameters in the climate system. when temperatures rise in the summer, sea ice and the snow on top of it start to melt. melt pond formation lowers the regional surface albedo of sea ice, because water has a significantly lower albedo than either snow or ice. as the surface albedo of sea ice diminishes, even more short-wave radiation is absorbed in the ice. this further enhances the melting, which again lowers the regional albedo. this process—the sea-ice albedo feedback mechanism—is suspected to amplify climate warming in the polar regions. conversely, a downward trend in global temperature would increase sea-ice albedo, which would in turn accelerate cooling (e.g., curry et al. 1995; curry et al. 2001; pedersen et al. 2009.) in its simplest form, the sea-ice albedo feedback mechanism operates by decreasing snowand ice-covered areas as a result of warming. however, different sea-ice models have shown that the sea-ice albedo feedback also operates on multiyear ice. even if an ice floe survives the melting season, it will still respond to the increase in summer temperatures. curry et al. (1995) have discussed the internal transformation processes that contribute to the sea-ice albedo feedback mechanism on multiyear ice. such processes include the melting of snow cover, diminishing of total ice thickness, opening of leads and the formation of melt ponds in the summer (curry et al. 1995). it is clear that the number of melt ponds markedly affects sea-ice albedo. for example, based on the results of the surface heat budget of the arctic (sheba) campaign carried out in the beaufort sea, perovich, grenfell et al. (2002) estimated that the total albedo of multiyear sea ice dropped from 0.8–0.9 in april to 0.4 in august, mainly as a result of melt pond formation. when modelling the sea-ice albedo feedback, and its climatic effects on polar regions, it is important to have data on melt pond polar research 29 2010 311–321 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 311 mailto:sankelo@ges.gla.ac.uk coverage on multiyear sea ice from various locations in the arctic sea. (multiyear sea ice is scarce in antarctic regions.) photographs, aerial or otherwise, are one possible means of studying the melt pond coverage on a region of ice. the areal extent of melt ponds can also be assessed by direct measurements performed on the ice: for example, by setting up a survey line and measuring the extent of melt ponds along the line (e.g., perovich, grenfell et al. 2002). the advantage of photographic data is that they allow the melt pond coverage to be obtained from a significantly larger area than could be examined directly on the ice. perovich, grenfell et al. (2002) have also shown that there is indeed good agreement between melt pond coverage measured directly on ice and melt pond coverage obtained from photographic data of the same region. several previous studies have obtained pond coverage from various photographic data sets (e.g., hanson 1961; langleben 1969, 1971; eicken et al. 1996; derksen et al. 1997; perovich & tucker 1997; tschudi et al. 1997; el naggar et al. 1998; fetterer & untersteiner 1998; tucker et al. 1999; tschudi et al. 2001; perovich, tucker et al. 2002; markus et al. 2003; tschudi et al. 2008). before the time of digital image processing, pond areas were measured from film photographs with a planimeter (langleben 1969, 1971). from the 1990s onwards, modern digital image processing techniques have been used to obtain the melt pond coverage from digitized photographs. the distinction of melt puddles from surrounding ice (and possibly open water) can be attempted in several different ways. some authors, working with digital greyscale images, have manually selected a suitable brightness threshold to separate ponds from their surroundings (eicken et al. 1996; derksen et al. 1997; el naggar et al. 1998). others (tschudi et al. 1997, 2001; markus et al. 2003; tschudi et al. 2008) have used colour images, and utilized the fact that the melt pond spectral albedos tend to be highest in the blue end of the optical wavelength region. yet another way of partitioning images of ice into different surface types is to use automated classification algorithms. fetterer & untersteiner (1998) have used supervised classification with manually selected training areas to distinguish melt ponds in photographs. although melt pond coverage on multiyear ice has been studied to a reasonable extent over a period of more than four decades, no simple generalizations can be made based on the available results. this is partly because of the aforementioned fact that research campaigns in the arctic are difficult and costly. it is not easy to obtain melt pond observations that cover a large areal extent and span a reasonably long time frame. the greatest number of aircraftor ground-based melt pond measurements have been performed in the beaufort and chukchi seas, and those results cannot necessarily be generalized for the whole arctic region. there is still demand for further research on melt pond coverage in diverse regions of the arctic, especially in the central arctic basin. the melt season of 2007 is especially interesting because of the sea-ice extent minimum that occurred in 2007. summer 2007 sea-ice extent minimum the pack ice of the arctic ocean has experienced remarkable shrinking and thinning in the last two decades. the most apparent changes are in the average and annual minimum sea-ice extents (comiso et al. 2008), and in the mean sea-ice thickness (e.g., rothrock et al. 1999; haas et al. 2008; kwok & rothrock 2009). the residence time of the sea ice in the arctic has also shortened (maslanik, fowler et al. 2007). these observations indicate that the changes in arctic pack ice are the result of changes in both thermodynamical and dynamical driving factors, connected with global warming enhanced by humaninduced greenhouse gas emissions. even in this context, the loss of sea ice during summer 2007 was exceptional. in september 2007, the minimum ice extent was only 4.3 ¥ 106 km2 (stroeve et al. 2008), which was approximately 2.5 ¥ 106 km2 less than the average arctic sea-ice extent in the period 1979–2000. reasons for the 2007 sea-ice extent minimum have been discussed in several recent studies. one important factor was preconditioning, a continuous decrease of ice thickness, but the main driving force seems to have been an anomalous atmospheric circulation. during summer 2007, a high sea-level pressure cell persisted over the western beaufort sea and northern canada. at the same time, sea-level pressure over siberia and europe was anomalously low. this circulation mode is known as the dipole anomaly (wang et al. 2009). it leads to southerly winds over the western beaufort, chukchi and east siberian seas, bringing warm air masses to the area (vihma et al. 2008), and increasing the northward transport of ice from it (maslanik, drobot et al. 2007; zhang et al. 2008; wang et al. 2009). kwok (2008) has reported an increased ice flow from the pacific to the atlantic sector of the arctic ocean during the summers of 2006 and 2007, contributing to sea-ice loss in the pacific sector. the persistent high sea-level pressure over the western arctic in summer 2007 also led to reduced cloud cover, which enabled more shortwave radiance to reach the ice (kay et al. 2008). the anomalous sea-ice transport pattern appears to have strengthened the ice albedo feedback mechanism and enhanced melting, especially at the bottom of the ice. melt pond formation at tara during summer 2007 p. sankelo et al. polar research 29 2010 311–321 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd312 zhang et al. (2008) estimated that approximately 30% of the sea-ice loss was directly related to anomalous ice advection, whereas 70% was the result of enhanced melting. methods instrumentation on 3 september 2006, a french private schooner tara and her crew set out to repeat the famous voyage of nansen’s ship fram. tara was anchored in the pack ice off the coast of siberia, north of the laptev sea. drifting with the ice, tara reached her northernmost point (88°32′n) on 28 may 2007, and exited the pack ice on the west side of the greenland sea on 21 january 2008 (gascard et al. 2008.) in spring 2007 tara hosted a research camp for the european scientific programme developing arctic modeling and observing capabilities for long-term environmental studies (damocles). as a part of the monitoring programme we deployed an automatically functioning camera and computer unit in the mast of tara. the unit was assembled by a finnish group who in 2008 formed a commercial, scientific digital photography company (vogon-it). the camera unit consisted of a consumer-grade digital camera, a computer and a global positioning system instrument, all placed inside a protective casing. the unit was mounted on the mast of tara, approximately 7 m above the ice surface. it stayed operational from 29 april to 22 july 2007, automatically obtaining a photograph every 10 min. photographs were stored on the hard disk of the computer, until the unit was dismounted and the photographs were retrieved. the physical area uniformly covered in the resulting time series of photographs corresponds to 6390 m2 on the ice, with a resolution of the perspective-corrected photographs equalling 5 ¥ 5 cm (fig. 1). about two months after the camera was set up the first signs of melt ponds appeared, on 19 june 2007. for unknown reasons, the camera stopped functioning on 22 july 2007, when the melt period was still well underway. the whole melt season was thus not captured on the photographic data set. however, a data set covering approximately one month of the melt season is still of great interest, especially when obtained from pack ice at 88°n, and during the melt season of 2007. image correction before the analysis of the images could start, several corrections were needed on the original data. first of all, barrel distortion and other possible geometric lens distortions were removed with the help of a grid image taken by the camera in question. lens distortions were in this case small, too slight to be detected by eye. unwanted portions of the image were cropped out: these included the sky and a strip of ice near the ship that had been frequently trampled on. some rigging of the ship was visible in the images, but as these later formed their own distinct spectral class, their effect could be removed after the classification. the most crucial correction performed on the images was perspective correction. whereas barrel distortion and other lens distortions are caused by the specificities of the camera optics, perspective distortion is a function of geometry, not the camera. in a photograph, distant objects seem smaller than those close by, precisely as is the case with human visual perception. thus, different areas in the same photograph cannot be compared with each other, unless the image is rectified so that every image pixel corresponds to an equally large physical area. an automated programme was created to eliminate the perspective distortion and to convert the images to the horizontal plane, corresponding to real physical distances on the ice (heiler unpubl. ms.). the area captured in the time series is comparable with a rectangle of approximately 80 ¥ 80 m, although because of the photographic perspective, the shape of the area is in fact a trapezoid (fig. 2a). tara shifted her position in the pack ice several times, changing the height of the camera from the ice surface. this introduced some complications to the image rectifying process, and acted as a source of error. as the height of the camera at any given time was not precisely known beforehand, the rectification would have in fact proved impossible had there not been convenient calibration fig. 1 a barrel distortion-corrected image of the study area on a cloudy day, 20 july 2007. melt pond formation at tara during summer 2007p. sankelo et al. polar research 29 2010 311–321 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 313 points (snow depth measurement poles) visible in the photographs. the height of the camera needed to be calculated anew, with the help of the known calibration points, for each time the ship did shift her attitude. after the height of the camera was found out, the rectification algorithm could be performed for each image. image classification the geometrically rectified photographs were partitioned into melt ponds and ice (bare or snow-covered) by unsupervised classification (fig. 2b). image classification was performed by iteratively arranging the spectral vectors of an image into a given number of separate clusters. these clusters are called spectral classes, and in remote sensing applications they normally correspond with different types of terrain. separate land cover or land use categories—such as forest, field, rock, ice, sweet water, salt water and urban areas—all have a specific spectral signature, although some overlap may occur between the spectral signatures of different classes (e.g., neteler & mitasova 2002.) in this study, the spectral vectors being clustered were points in three-dimensional red–green–blue (rgb) colour space making up the colour images taken by a digital camera. in general, the wavelength bands used in image classification need not be red, blue and green, nor do they need to lie in the visible region at all. the wavelength bands being used in the analysis depend on the imaging instrument and the aims of the study. water absorbs infrared radiation a lot more effectively than snow or ice, and thus it might be beneficial to use an infrared band for the detection of ponds on ice. the instrument used in this study, however, did not allow for that option. the classification of images was performed using geographic resources analysis support system (grass) software, a free, open-source geographical information system, with some additional accuracy checks performed using openev open-source software. both supervised and unsupervised classification methods were tried, as well as alternative methods of partitioning the image. those included choosing a suitable brightness threshold level to separate ponds from ice, and exploiting the difference between the blue and the red channels. unsupervised classification was deemed to produce the most reasonable results, and to be somewhat less prone to observer bias than other methods that were tried. weather and illumination conditions affected both the classification procedure and the resulting accuracy. on sunny days the snow and ice features protruding from the ice could be seen to cast shadows. the spectral signature of bluish shadows on snow was similar to that of the blue melt ponds, causing overlap with ponds. direct sunlight also brought forth more details from the snow and ice (e.g., surface roughness), adding to the number of spectral classes needed for a successful classification. on a cloudy day, with dull illumination, the unponded ice had, overall, a more uniform appearance. this effect was aided by the fact that during cloudy periods it often snowed, and freshly fallen snow temporarily rendered the ice surface more uniform. when performing the image classification for sunny days, typically one or two more spectral classes were needed than for cloudy days. the extra spectral classes allowed for the pond pixels and shadow pixels to fall into different spectral classes, instead of the same one. however, some pond/shadow overlap remained even in the most successful classifications for sunny days, rendering the classification somewhat less accurate for sunny images than for cloudy ones. the fact that spectral reflectance of both ponds and ice surfaces vary intrinsically according to illumination conditions did not introduce further difficulties to the classification: shadows on the ice were by far the greatest challenge. to eliminate the possible unwanted effects springing from changing illumination conditions, we only analysed images taken at local noon. it must be stressed that without any additional data from the same region, such as direct melt pond coverage measurements made on the ice, the absolute error of the classification results cannot be reliably established. the fig. 2 (a) a geometrically-corrected image with sky and foreground removed, 20 july 2007. (b) the classified image, 20 july 2007. rigging of the ship and instruments form their own spectral class on ice (coloured black), with some overlap with the very darkest areas of the ponds (coloured blue). four spectral classes were needed to create this classification (rigging, ponds and two types of ice). melt pond formation at tara during summer 2007 p. sankelo et al. polar research 29 2010 311–321 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd314 accuracy of the partitioning results was in this case estimated by first of all comparing the partitioning results with the original photographs. when the partitioning method seemed to produce a reasonable distribution of melt ponds, additional checks were performed by using the same partitioning methods with different software, establishing that different classification algorithms produced similar results with the same number of spectral classes chosen. the error assessment will be discussed more extensively below. results melt pond coverage figure 3 presents melt pond fractions calculated from the classified images, alongside surface air temperature and net radiation. melt pond coverage was obtained for 22 days during the data collection period. only one classified image per day was produced. the images chosen for classification were all taken at local noon, so that the illumination conditions from one chosen photograph to the next might vary as little as possible. the choice had more to do with the direction of the sun than its elevation, which does not vary greatly during midsummer at such high latitude. (for the same reason, no diurnal cycle in pond area was observed in the photograph set.) six noon images out of 28 were discarded because of weather conditions causing very poor visibility. the tara atmospheric monitoring programme included air temperature, wind speed, upward and downward shortand long-wave radiation measurement and tethersonde soundings (vihma et al. 2008). the air temperature was measured 2 m above the ice surface. the net radiation data used in this study is the sum of all the radiation components. the weather station was located approximately 100 m from the monitoring area of the melt ponds. emergence of the first melt ponds was preceded by a preconditioning period of 2 weeks, when the radiation 4 june 14 june 24 june 4 july 14 july 0 5 10 15 20 (% ) melt pond fraction 4 june 14 june 24 june 4 july 14 july −2 −1 0 1 air temperature (o c ) 4 june 14 june 24 june 4 july 14 july 0 50 100 net radiation (w /m 2 ) fig. 3 melt pond fraction, air temperature and net radiation measured at tara in june–july 2007. melt pond formation at tara during summer 2007p. sankelo et al. polar research 29 2010 311–321 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 315 balance turned positive. at the time of the summer solstice, the daily mean net radiation was 50–70 w m–2. the mean air temperature was mostly negative during the preconditioning period, but during 17–19 june it was above zero throughout the day. slight depressions on the snow cover are first observable on the 19 june 2007 image, indicating the spots where the first melt ponds appear. the first distinct melt ponds formed on 21 june 2007. the two tiny ponds in the 21 june image are too small to be distinguished as a separate spectral class, and no reliable estimate on melt pond coverage is obtained until 24 june 2007, when the melt pond coverage had reached 3%. the camera was operational until the early morning of 22 july 2007, and thus noon images have been obtained for a period of 28 days. out of those 28 days, melt pond coverage has been calculated for 22 days. although the very onset of melt is not captured by the classification algorithm, it can be estimated based on the acquired images that the melt pond fraction increased from 0 to 3% in 5 days (20–24 june 2007). during that time, the melt pond fraction grew by approximately 0.6% every day. from 24 june 2007 onwards, the growth rate more than doubled: the melt pond fraction increased from 3% to approximately 14% in 7 days. after 30 june 2007 there’s an unfortunate gap in the data: images from 1 to 4 july 2007 could not be geometrically corrected because of foggy and snowy weather conditions. images from those days are still clear enough to form an estimate that the rapid phase of the melt did indeed end on 30 june 2007. the melt pond fraction stopped growing significantly and started to fluctuate around 12% for approximately 2 weeks (1–15 july 2007). during that period, the daily mean air temperature was always below 0°c. the mean net radiation was approximately 50 w m–2, whereas the daily mean maximum and minimum net radiation levels were 84 and 22 w m–2, respectively. the day-to-day variations of melt pond fraction and net radiation were well correlated (fig. 4). during the last days of the data collection period, the air temperatures were again above zero and the melt pond coverage increased slightly, reaching the vicinity of 15% by 21 july 2007. it is likely that when the melt pond fraction had reached 15%, the melt season was still well under way. snow-depth data from tara indicates that the snow level started rising again in mid-august. a snapshot taken by a crew member from tara’s mast on 20 august 2007 yields a melt pond coverage of 37 � 5%. the estimate is relatively imprecise, as the height from which the image was taken is not known, and thus the image could not be rigorously rectified. however, we can conjecture that the maximum melt pond coverage was reached in august, and totalled more than 30%. estimated errors the error in the calculated melt pond fractions is estimated at �2%: that is, any given percentage is inaccurate by �2 in percentage units (as opposed to the relative error being only 2%, which is not the case here). it is important to stress that there is no reliable way of estimating the absolute error made in calculating the melt pond percentage, at least not without suitable auxiliary data to validate the results. the classification success was assessed by first comparing the results with the original images. it was clear that a well-premeditated choice of parameters was needed for the classification to succeed at all, with the most important parameter being the number of spectral classes chosen. by changing the number of spectral classes 5 july 7 july 9 july 11 july 12 july 14 july 16 july 18 july 20 july −30 −20 −10 0 10 20 (w /m 2 ) , (1 /1 0 0 0 ) anomalies of melt pond fraction and net radiation date fig. 4 daily mean net radiation (line) and melt pond fraction (circle) anomalies during 5–21 july 2007. melt pond formation at tara during summer 2007 p. sankelo et al. polar research 29 2010 311–321 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd316 chosen, it was often possible to produce more than one satisfactory classification result. the parameters that were chosen for each classification were the ones that seemed to produce the best result, compared with the original photographs. the process of choosing the most satisfactory result is, or course, highly subjective and prone to errors. however, the results that clearly appeared satisfactory all fell within �2% of the result from the classification attempt deemed best: hence the choice of �2% for the error estimate. the openev program was also employed to double check the results produced by grass gis. the calculated melt pond fractions did fall inside the �2% margin, even when the classification was performed with another program. some checks were also performed by using the alternative image-partitioning methods mentioned earlier, and their best-looking results again fell into the same �2% margin. to be cautious, a classification from a sunny day was used to quantify the error, as the classification was somewhat less accurate for sunny images. there are multiple sources of error inherent in the image correction process, as well as in the classification itself. the physical parameters needed for image rectification were selected from images by hand, which means that they can hardly be absolute. the error inherent in such a process is difficult to quantify. another type of inaccuracy arises from the ice topography itself. the ice surface is far from smooth: there are protruding features ranging from a small ridge to piles of snow. higher parts of the ice field may block some low-lying features from the view of the camera. a numerical estimate of an error rising from this effect has not been attempted, because a reliable estimate would require more detailed knowledge of the ice topography on site. discussion comparison with previous results our results comprise three main aspects of interest: date of melt onset, early development of melt pond areas and absolute value of melt pond fraction. all three are compared with previous results from the arctic, mainly those derived from photographic data sets. for a more thorough comparison, other types of melt pond measurements are also examined. melt onset. the date of melt onset is a parameter of great interest, because the quantity of solar energy absorbed into the ice–ocean system correlates more strongly with the melt onset date than with the overall length of the melt season. melt pond formation affects the way the incoming solar radiation is partitioned into portions reflected by the ice, absorbed in the ice and transmitted through the ice. the way this partitioning is established early on in the season has a cumulative effect to the quantity of solar energy absorbed by the system throughout the season. if weather conditions trigger an early onset of melt, the energy budget of the system is influenced for the whole season (perovich et al. 2007). during the sheba campaign, for example, melt onset was brought about by a rainfall event in late may (perovich, grenfell et al. 2002). at tara’s location, 88°n, 124°e, the first melt ponds appeared on 20 june 2007. melt onset at tara was not triggered by a precipitation event; on the contrary, it happened after a clear and sunny spell. appearance of the melt ponds was preceded by a 2-week period of positive radiation balance, and 3 days when the air temperature was above the freezing point of water. according to ice mass-balance buoy (imb) data acquired by perovich et al. (2008), the melt season 2007 commenced in early june in the beaufort sea region. the melt season is expected to begin later at higher latitudes (e.g., tschudi et al. 2008), and our result is in accord with that. imbs deployed near the north pole in the years 2000–05 have recorded snow surface melt-onset dates from 8 to 20 june, again in agreement with our result (richter-menge et al. 2006). in light of the imb data, the onset of melt at tara does not appear in any way exceptional, despite the anomalous weather and ice conditions in the arctic during summer 2007. it is worth noting that near tara the snow did not melt completely during the period of observation: by 21 july 2007 the unponded ice was still covered by snow. although imbs deployed near the north pole in 2000–05 typically recorded snow surface melt onsets in mid-june, the snow cover melted away on average in mid-july, if at all (richter-menge et al. 2006). again, this is in line with our results. early pond evolution evolution. the rapid growth of the melt pond fraction shown in fig. 3 is immediately comparable with previous melt pond studies (e.g., derksen et al. 1997; perovich, tucker et al. 2002; tschudi et al. 2008). quoting from perovich, tucker et al. (2002: 24–27): “in mid-june ponds cover a few percent of the ice, but then, in just a few days, between 15 and 18 june, [pond fraction] jumps by a factor of five from 0.04 to 0.20”. this is very much in accord with the temporal evolution observed near tara: the pond fraction increased by approximately a factor of 4.5 (from 3 to 14%) within a week. it is not surprising that the melt pond fraction should rise steeply soon after the ponds have started forming. when the wet snow on top of the ice starts melting, there melt pond formation at tara during summer 2007p. sankelo et al. polar research 29 2010 311–321 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 317 is a rapid influx of water from the melting snow. this water will form melt pools, usually located in the depressions on the ice. ponds have a lower albedo than the surrounding snow and ice, and thus they absorb more heat. the melt rate of ice beneath the ponds is two to three times higher than that of the ice surrounding the ponds. this implies that once the ponds have fully formed, the ongoing melt tends to take place under the melt pools, decelerating the growth of the pool diameter (fetterer & untersteiner 1998). pond fraction. it is difficult to compare the absolute values of melt pond fractions with previous studies: the majority of previous melt pond coverage measurements have been made at different times and locations than the ones in this study. our pond fraction time series begins on 24 june 2007, when tara was at 88°11′n, 124°20′e, and ends on 21 july 2007 at 87°56′n, 43°16′e. there is scarce pond coverage data on multiyear ice that far north, and in any case there is a lot of interannual variability in the melt conditions. melt pond fractions computed from various photographic data sets are given in table 1. only results from the 1990s and onwards are included. in some cases results are much more detailed than the summary given here (i.e., a long transect with varying melt pond fractions). in some studies pond fractions were originally given as the fraction of ponded ice of the whole area photographed (i.e., ice + open water). in table 1 we have expressed the pond fractions as the fraction of ponded compared with unponded ice. markus et al. (2003) and tschudi et al. (2008) have used aircraft data mainly as a validation tool for satellite-based melt pond fraction measurements, and reported further results for a larger study area and time range. all in all, the results display a considerable variety. our result of 15% by 21 july and more than 30% by midaugust on a multiyear floe are in line with most of the results presented in table 1, and especially with those reported for multiyear ice. this may be rather surprising, bearing in mind that our results are obtained some 10° further north than most previous studies. tucker et al. (1999) did obtain photographic data at 88°n on 18 august 1994, and only frozen ponds were observed, with the melt season being over. contrasted with our estimate of 37 � 5% pond coverage on 20 august 2007, the difference is striking, but comparison with one single date does not warrant far-reaching conclusions. melt pond fractions at latitudes comparable with this study have been estimated from on board a ship during two trans-arctic cruises: the arctic ocean section (aos) in 1994 (tucker et al. 1999) and the healy oden table 1 melt pond fractions computed from various photographic data sets in the arctic. pond fractions are expressed as the fraction of ponded compared with unponded ice. author location date pond fraction from photographic data eicken et al. 1996 eurasian arctic 2 days in august 1991 4 days in august 1993 average of 16% in 1991 average of 19% in 1993 derksen et al. 1997 canadian arctic archipelago (ca.74°n) 7–9 july 1995 maximum of 53% perovich et al. 1997 76°n, 172°w 31 july 1994 average of 12% tschudi et al. 1997 beaufort sea (ca.72°n) 12 september 1994 average of 20 � 8% el naggar et al. 1998 northeast water polynya (ca.78°n) 6–30 july 1993 34.2 � 14.26% on fyia 19.0 � 6.85 % on myib fetterer & untersteiner 1998 beaufort sea july 1993 july & august 1994 entire summer 1995 40–50% on fyia 30% on myib tucker et al. 1999 arctic ocean (76°n–88°n) 31 july 1994 13 august 1994 18 august 1994 12% at 76°n (31 july) 3% at 84°n (13 august) only frozen ponds at 88°n (18 august) yackel et al. 2000 wellington channel (75°n, 93°w) 30 june 1997 3 july 1997 ca. 10–20% along a transect, less on older/ rougher ice tschudi et al. 2001 beaufort and eastern chukchi sea (ca.78°n) 5 days in july 1998 smallest 24.6 � 6.2% (8 july) largest 34.1 � 8.4% (24 july) perovich et al. 2002 beaufort sea twelve days in 5 apr–4 oct 1998 maximum of 24% (7 august) markus et al. 2003 baffin bay 27 june 2002 ca. 19–68% along a transect tschudi et al. 2008 beaufort and chukchi seas (70°n–80°n) 13 june 2004 16.4% perovich et al. 2009 arctic ocean (81°n, 177°e) 22 august 2005 average of ca. 31% a multiyear ice. b first-year ice. melt pond formation at tara during summer 2007 p. sankelo et al. polar research 29 2010 311–321 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd318 trans-atlantic expedition (hotrax) in 2005 (perovich et al. 2009). aerial photographs from melt ponds were obtained in connection with both cruises, as indicated in table 1, but on-board estimates from higher latitudes offer a more fruitful comparison here. at latitude band 85–90°n of the northward leg, in the late summer, both aos and hotrax observed an average melt pond fraction of 6%. aos crossed the latitude band in august, and hotrax crossed in the first half of september. our results again seem considerably larger, especially when contrasted with the aos result of 6% in august. representativeness of the site as seen in table 1, the variability in reported melt pond fractions from the arctic is great. it is well-documented that sea ice displays large spatial and temporal variability, and that the differences in ice morphology lead to different ponding extents and patterns. in general, first-year ice is smoother than multiyear ice, and tends to have larger pond fractions (e.g., el naggar 1998; fetterer & untersteiner 1998; yackel et al. 2000; perovich et al. 2009). tschudi et al. (2008) have reported an increase in pond fraction with increasing latitude (at 70–80°n), despite the fact that the melt season starts later further in the north. they attribute this to ice growing more abundant and predominantly thicker with increasing latitude, hence allowing for less meltwater run-off. because the thickness and overall morphology of ice play a large role in determining the melt pond fraction, and because sea ice is highly variable in these aspects, one must carefully consider the representativeness of the results obtained here. in the context of the arctic ocean, an area of 6400 m2 is but a point measurement. we argue, however, that the results can be extended to a larger area, especially where a similar ice type predominates. perovich & richter-menge (2006) have examined the representativeness of imb point measurements performed on multiyear ice. they conclude that a point mass-balance measurement can represent ice conditions on a larger area, provided the measurement site is correctly chosen. the argument is based on more than 100 ice mass-balance observations collected during the 1997–98 sheba campaign, covering an area of 100 km2. a wisely chosen point measurement site for mass-balance observation is a multiyear ice floe that is not deformed, and is of average size, compared with its neighbouring floes. for the purposes of imb measurements, the ice must also be “unponded”: that is, the thermistor string should not be deployed directly at a melt pond site. the last condition cannot apply for the melt pond areal fraction measurement, but otherwise we believe the melt pond fraction measurements performed on a multiyear ice floe can be generalized with largely the same provisos as ice mass-balance measurements. after all, the criteria for imb measurement sites have been selected so that the site itself should be representative of the perennial ice pack. if the criteria for a representative site are fulfilled, most likely the ponding on site is not highly anomalous either. our study area was located on a mainly multiyear ice floe that was of average size compared with its vicinity. some new ice had been incorporated into the floe, where leads had previously opened, but this did not affect our study area. there were some protruding features in the camera view, including a smallish ridge (<2 m high), but generally the ice was not deformed. all in all, we believe our study area to be a representative one, at least in the context of the neighbouring ice floes, on the spatial scale of ca. 10 km. our conclusion is aided by the fact that, despite our rather limited study area, both the date of melt onset and the early development of melt ponds agree well with previous results. this fosters the belief that the pond evolution on site was not anomalous. in conclusion, the timing of melt onset and the subsequent rapid pond growth accord well with previous studies. the absolute values of melt pond coverage near tara seem higher than expected, insofar as comparison with previous studies is possible. the exceptional sea-ice melt conditions of summer 2007 may be reflected in the melt pond coverage results presented here, but we cannot absolutely conclude that. it should be borne in mind that melt onset did not happen especially early, and imb point measurement data from the north pole region show no significant increase in either surface or bottom melt during the summer of 2007 (perovich et al. 2008). acknowledgements this study was supported by the european union fp6 integrated project damocles. the crew of tara and the tarawaka logistics group are thanked for their realization of the field programme. we also thank the karhukamera team, led by mikko viitapohja, and vogon-it ltd. for providing the time-lapse unit for this study. the tara meteorological observations were made by jaak jaagus, erko jakobson, timo palo and timo vihma. the expedition was led by etienne bourgois, and was sponsored by the fashion company agnés b. comments by two anonymous reviewers greatly improved this paper and are gratefully acknowledged. references comiso j.c., parkinson c.l., gersten r. & stock l. 2008. accelerated decline in the arctic sea ice cover. geophysical research letters 35, l01703, doi: 10.1029/2007gl031972. melt pond formation at tara during summer 2007p. sankelo et al. polar research 29 2010 311–321 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 319 curry j.a., schramm j.l. & ebert e.e. 1995. sea ice–albedo climate feedback mechanism. journal of climate 8, 240–247. curry j.a., schramm j.l., perovich d.k. & pinto j.o. 2001. applications of sheba/fire data to evaluation of snow/ ice albedo parameterizations. journal of geophysical research—atmospheres 106, 15 345–15 355. derksen c., piwowar j. & ledrew e. 1997. sea-ice melt pond fraction as determined from low level aerial photographs. arctic and alpine research 29, 345–351. eicken h., gradinger r., ivanov b., makshtas a. & pác r. 1996. surface melt puddles on multi-year sea ice in the eurasian arctic. in p. lemke et al. (eds.): proceedings of the acsys conference on the dynamics of the arctic climate system: göteborg, sweden, 7–10 november 1994. wcrp 94. pp. 267–271. geneva: world meteorological organization. el naggar s., garrity c. & ramseier r.o. 1998. the modelling of sea ice melt water ponds for the high arctic using an airborne line scan camera, and applied to the satellite special sensor microwave/imager (ssm/i). international journal of remote sensing 19, 2372–2394. fetterer f. & untersteiner n. 1998. observations of melt ponds on arctic sea ice. journal of geophysical research—oceans 103, 24 821–24 835. gascard j.-c., festy j., le goff h., weber m., bruemmer b., offermann m., doble m., wadhams p., forsberg r., hanson s., skourup h., gerland s., nicolaus m., metaxian j.-p., grangeon j., haapala j., rinne e., haas c., heygster g., jakobson e., palo t., wilkinson j., kaleschke l., claffey k., elder b. & bottenheim j. 2008. exploring arctic transpolar drift during dramatic sea ice retreat. eos, transactions of the american geophysical union 89, 21–28. haas c., pfaffling a., hendricks s., rabenstein l., etienne j.-l. & rigor i. 2008. reduced ice thickness in arctic transpolar drift favors rapid ice retreat. geophysical research letters 35, l17501, doi: 10.1029/2008gl034457. hanson k.j. 1961. the albedo of sea ice and ice islands in the arctic ocean basin. arctic 14, 188–196. kay j.e., l’ecuyer t., gettelman a., stephens g. & o’dell c. 2008. the contribution of cloud and radiation anomalies to the 2007 arctic sea ice extent minimum. geophysical research letters 35, l08503, doi: 10.1029/2008gl033451. kwok r. 2008. summer sea ice motion from the 18 ghz channel of amsr-e and the exchange of sea ice between the pacific and atlantic sectors. geophysical research letters 35, l03504, doi: 10.1029/2007gl032692. kwok r. & rothrock d.a. 2009. decline in arctic sea ice thickness from submarine and icesat records: 1958–2008. geophysical research letters 36, l15501, doi: 10.1029/ 2009gl039035. langleben m.p. 1969. albedo and degree of puddling of a melting cover of sea ice. journal of glaciology 8, 407–412. langleben m.p. 1971. albedo of melting sea ice in the southern beaufort sea. journal of glaciology 10, 101–104. markus t., cavalieri d.j., tschudi m.a. & ivanoff a. 2003. comparison of aerial video and landsat 7 data over ponded sea ice. remote sensing of environment 86, 458–469. maslanik j., drobot s., fowler c., emery w. & barry r. 2007. on the arctic climate paradox and the continuing role of atmospheric circulation in affecting sea ice conditions. geophysical research letters 34, l03711, doi: 10.1029/2006gl028269. maslanik j.a., fowler c., stroeve j., drobot s., zwally j., yi d. & emery w. 2007. a younger, thinner arctic ice cover: increased potential for rapid, extensive sea-ice loss. geophysical research letters 34, l24501, doi: 10.1029/ 2007gl032043. neteler m. & mitasova h. 2002. open source gis: a grass gis approach. norwell, ma, usa: kluwer. pedersen c.a., roeckner e., lüthje m. & winther j.-g. 2009. a new sea ice albedo scheme including melt ponds for echam5 general circulation model. journal of geophysical research—atmospheres 114, d08101, doi: 10.1029/2008jd010440. perovich d.k., grenfell t.c., light b., elder b.c., harbeck j., polashenski c., tucker w.b. & stelmach c. 2009. transpolar observations of the morphological properties of arctic sea ice. journal of geophysical research—oceans 114, c00a04, doi: 10.1029/2008jc004892. perovich d.k., grenfell t.c., light b. & hobbs p.v. 2002. seasonal evolution of the albedo of multiyear arctic sea ice. journal of geophysical research—oceans 107, 8044, doi: 10.1029/2000jc000438. perovich d.k., nghiem s.v., markus t. & schweiger a. 2007. seasonal evolution and interannual variability of the local solar energy absorbed by the arctic sea ice–ocean system. journal of geophysical research—oceans 112, c03005, doi: 10.1029/2006jc003558. perovich d. & richter-menge j.a. 2006. from points to poles: extrapolating point measurements of sea-ice mass balance. annals of glaciology 44, 188–192. perovich d.k., richter-menge j.a. & jones k.f. 2008. sunlight, water, and ice: extreme arctic sea ice melt during the summer of 2007. geophysical research letters 35, l11501, doi: 10.1029/2008gl034007. perovich d.k. & tucker w.b. iii 1997. arctic sea-ice conditions and the distribution of solar radiation during summer. annals of glaciology 25, 445–450. perovich d.k., tucker w.b. iii & ligett k.a. 2002. aerial observations of the evolution of ice surface conditions during summer. journal of geophysical research—oceans 107, 8048, doi: 10.1029/2000jc000449. richter-menge j.a., perovich d.k., elder b.c., claffey k., rigor i. & otmeyer m. 2006. ice mass-balance buoys: a tool for measuring and attributing changes in the thickness of the arctic sea-ice cover. annals of glaciology 44, 205–210. rothrock d., yu y. & maykut g. 1999. thinning of the arctic sea-ice cover. geophysical research letters 26, 3469–3472. stroeve j., serreze m., drobot s., gearheard s., holland m., maslanik j., meier w. & scambos t. 2008. arctic sea ice extent plummets in 2007. eos, transactions of the american geophysical union 89, 13–14. melt pond formation at tara during summer 2007 p. sankelo et al. polar research 29 2010 311–321 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd320 tschudi m.a., curry j.a. & maslanik j.a. 1997. determination of areal surface-featured coverage in the beaufort sea using aircraft video data. annals of glaciology 25, 434–438. tschudi m.a., curry j.a. & maslanik j.a. 2001. airborne observations of summertime surface features and their effect on surface albedo during fire/sheba. journal of geophysical research—atmospheres 106, 15 335–15 344. tschudi m.a., maslanik j.a. & perovich d.k. 2008. derivation of melt pond coverage on arctic sea ice using modis observations. remote sensing of environment 112, 2605–2614. tucker w.b., gow a.j., meese d.a. & bosworth h.w. 1999. physical characteristics of summer sea ice across the arctic ocean. journal of geophysical research—oceans 104, 1489– 1504. vihma t., jaagus j., jakobson e. & palo t. 2008. meteorological conditions in the arctic ocean in spring and summer 2007 as recorded on the drifting ice station tara. geophysical reseach letters 35, l18706, doi: 10.1029/ 2008gl034681. wang j., zhang j., watanabe e., ikeda m., mizobata k., walsh j.e., bai x. & wu b. 2009. is the dipole anomaly a major driver to record lows in arctic summer sea ice extent? geophysical research letters 36, l05706, doi: 10.1029/2008gl036706. yackel j.j., barber d.g. & hanesiak j.m. 2000. melt ponds on sea ice in the canadian archipelago. 1. variability in morphological and radiative properties. journal of geophysical research—oceans 105, 22 049–22 060. zhang j., lindsay r., steele m. & schweiger a. 2008. what drove the dramatic retreat of arctic sea ice during summer 2007? geophysical research letters 35, l11505, doi: 10.1029/ 2008gl034005. melt pond formation at tara during summer 2007p. sankelo et al. polar research 29 2010 311–321 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 321 data processing and interpretation of sea radiance factor measurements helgi arst and tilt kutser arst, h. & kutser, t. 1994: data processing and interpretation of sea radiance factor measurements. polar research 13, 3-12. problems in the interpretation of passive optical remote sensing data obtained by telespectrometric measurements on hoard a research vessel (or aircraft) are discussed. two methods are considered: (1) the correlation method. where correlative relationships between the remotely sensed spectra and concentrations of optically active substances in the water are determined and corresponding regression formulae found; (2) the similarity method. where the remotely scnscd spectrum is compared with the multitude of spectra obtained by means of model calculations. the application of these methods and analysis of the results are madc using our remote and in situ data. it is found that the correlation method is far from being general (the regression parameters depend on the location. season and weather conditions), but it has the advantage of heing applicable without the need t o describe the aquatic environment by a theoretical model. the similarity method is much more general but involves difficulties in including the optical properties of the aquatic environment in the theoretical model, cspccially the backscattering properties of several types of suspended matter in the water bodies. some aspects of detecting oil-slick pollution on the sea surface by means of passive optical remote sensing methods are discussed and corresponding examples are shown helgi arst and t . kutser, estonian marine institute, lai st. 32, tallinn, ee-0001, estonia. introduction throughout the world, passive optical remote sensing from satellites has become one of the main methods of ocean research. it is obvious that for operative information on a global scale the use of satellite measurements is inevitable. however, the interpretation of satellite data is often difficult, not only because of the disturbing influence of the atmosphere and clouds, but also because of some specific features of the objects under investigation. this is particularly noticeable in the case of marginal seas and inland waters, where suspended matter can vary in type and amount over short spatial and temporal scales, concentrations of these substances often being significantly higher than in open ocean waters. consequently, remote measurements from air craft, helicopters or ships are also of value and in need of further development. it must also be noted that for the elaboration and application of any remote sensing method, one must proceed through a couple of intermediate stages, where in situ measurements and numerical experiments are made in parallel with remote observations to gather the material to “calibrate” the method and test its efficiency. in the present paper we consider the passive (the sun being the source of radiation) optical remote sensing method in the case of mul ticomponental waters. this method represents the following inverse problem: above the water mass under consideration the spectra of the solar radiation reflected from the water surface and backscattered from the water mass are measured by a telespectrometer; on the basis of the numeri cal values of the results obtained and the charac teristics describing the location of extreme values and shapes of these spectra, one tries to estimate the clarity of the water, and the type and amount of optically active substances in the sea. this task is relatively easy if there is only one substance in the water (e.g., phytoplankton). in such a case all the changes in the spectrum of the light back scattered from the water mass into the atmos phere are caused by the absorbing and scattering properties of the water itself and of this single substance. but if there are several optically active substances in the water, their influence on the spectra of the upwelling light is difficult t o dis tinguish. so, in the case of a multicomponental water mass, the task of solving the passive optical remote sensing inverse problem may be com 4 h. arst & t . kutser plicated and, in general, an exact and unique solution does not exist. here it must be emphas ized that optical remote sensing always represents an inverse problem, which in most cases is “incor rect” (sensitive to the minor errors in the initial experimental data and having no unique solution). to obtain a unique solution, additional information, and the application of some special mathematical procedures, are needed (shifrin 1983). for example, it is known that the numerical values of the spectrum of the upwelling light depend rather critically o n the total back scattering coefficient of the water environment under consideration. the backscattering coef ficient b*, in turn, depends on the specific scat tering coefficients (bi), of the substances (i) in the water the concentrations of these substances (ci) and their backscattering probabilities ( h ) , i.e. b* = zb,bici. it is thus clear that several com binations of 8 , bi and ci may give the same b* and we cannot recreate the values of ci if we know only the product h b i ; the separate values of and bi are needed. in the case of multicomponental waters some other difficulties may arise in determining the type and amount of the optically active substances in the water. for instance, the strong absorption of light by yellow substance overshadows the influence on the spectra of the absorption maxi mum of chlorophyll a near 440nm, which com plicates the estimation of the chlorophyll concentration from remote sensing data. conse quently, in the case of turbid, multicomponental waters, the problems of interpretation of optical remote sensing data need special attention (the term “interpretation” here meaning the process of estimating the water quality, the type and amount of optically active substances in the water on the basis of optical remote sensing data). in the case of telespectrometrical measure ments directed to the nadir point on board a ship or aircraft, the influence of the air layer between the sea surface and receiver on the measured signal is small and the measured upwelling radi ance lu(li) consists of two main components: (1) solar radiance reflected from the wavy sea surface, l r ( a ) ; (2) solar radiance backscattered from the depths of the water mass, l d ( a ) : lu(a) = l r ( l i ) -k ld(li). (1) here li is the wavelength of light. the spectra of the component l r give infor mation about the state of the sea surface (undu lation characteristics, oil slick pollution, etc.) and the spectra of the component ld about the optical characteristics of the water mass (optically active substances in the water). by means of additional telespectrometrical measurements it is possible t o determine sep arately the value l r ( a ) and also the radiance factor r(a) (arst, pozdnyakov & rozenstein 1990): l r ( a ) 0 . 0 2 l z ( a ) . (2) here l z ( a ) is the spectral radiance of the zenith point of the sky. = rr(a) + r d ( a ) , where ed(a) is the spectral downwelling irradiance at the sea surface. so, if both lr and ld (and also ed) are known, it is possible t o compute the corresponding components of the radiance factor, rr(a) and rd(a). it must be noted that formula (2) for determining lr gives satis factory results only in conditions where sun glint does not significantly influence the value of lr. if sun glint is significant, the component lr has to be determined by means of more complicated model calculations (arst, pozdnyakov & roz enstein 1990). note that if the measurement direc tion is not far from nadir, the influence of sun glint on lr increases with increasing wind speed and decreasing solar zenith angle. in polar and arctic seas, where the sun is close to the horizon, formula (2) is usually applicable without problems (with the exception of surface pollution by oil or foam). it must be mentioned that a similar optical inverse problem exists also in the case of under water optical measurements: determining on the basis of the measured spectra of the attenuation coefficient (or absorption and scattering coef ficients) the type and amount of optically active substances, each of them giving a certain con tribution to the light attenuation in the water mass under consideration. here the task is easier in comparison with the remote sensing inverse prob lem because there is no disturbing “reflected” component, and the information about the back scattering properties is not of great importance. in the present paper we consider the two inter pretation methods for passive optical remote sens ing data and demonstrate the corresponding data processing and interpretation of sea radiance factor measurements 5 results. as shown below, each of these methods has both positive and negative features. in addition, some special problems in the application of passive optical remote sensing for the detection of oil-slick pollution on the sea surface are discussed. two methods for the interpretation of passive optical remote sensing data as mentioned above we use the term “inter pretation” in the sense of the process of obtaining information about the waterbody on the basis of optical remote sensing data. we have avoided the phrase “solution of the optical remote sensing inverse problem” for the reasons described above: there is no exact solution and it may not be unique. two methods for the interpretation of the pass ive optical remote sensing data were considered. the first, the widely used classical method, we named the “correlation method”. in this method, a series of telespectrometric observations and sim ultaneous in situ measurements are made in order to find algorithms connecting the remote sensing and other characteristics of the water (e.g., rela tive transparency of the water, chlorophyll con centration in the water, etc.). the algorithms are obtained by investigating correlations between the different characteristics. algorithms obtained by different authors show linear or non-linear interdependence between several characteristics under consideration (arst, pozdnyakov & roz enstein 1990; arst et al. 1989; kirk 1989; bukata et al. 1991; carder et al. 1991; mitchell & holm hansen 1991). this kind of investigation involves the problem of how to choose the most suitable characteristics of the remote sensing spectra for the correlation analysis. when the first steps were made in optical remote sensing, optical devices were capable of measuring radiation at 2-4 wave lengths only. the ratios r(al)/r(az) (color indices) or combinations of 2-3 color indices were used to seek connections between remote sensing and in situ data. since then, equipment has improved and it has become possible to measure the full spectrum i n the photosynthetically active region (with a spectral resolution of about 5-10 nm). in this case one can characterize the shape of the spectra not only by colour indices or other spectral characteristics, but also using integral charac teristics (afonin & kravtsov 1986; arst et al. 1990; kutser et al. 1993). however, as mentioned above, the remote sensing characteristics and cor responding algorithms recommended by different authors are mostly rather dissimilar from each other. the second, alternative method for the inter pretation of optical remote sensing data we call the “similarity method”. the basis of this method is the comparison of the measured full spectrum of r(a) (or rd(a)) with the multitude of the cor responding spectra determined by means of model calculations. from this group of spectra we try to identify the one which is the closest to the experimental spectrum. thereafter we can determine the concentrations of the optically active substances in the water for the exper imental spectrum under consideration, assuming them to be the same as the corresponding initial data for computing the “most similar” theoretical spectrum. note that for this kind of comparison normalized spectral curves may also be used. the “similarity” method is not new (e.g., its principal description is presented also in the paper by lokk & purga (1982)), nor is it widely used. the efficiency of this method depends essentially on the validity of the mathematical model describing the spectra of r(a) or rd(a). the prin cipal difficulty is with the detailed description of the absorptive and scattering properties of opti cally active material in the water (e.g., different types of phytoplankton pigments, organic and inorganic substances, dead and half-dead blue green algae, etc.), especially the determination of the backscattering coefficients. our estimations show that the scattering (and backscattering) coefficients presented in handbooks and mono graphs (mainly for the open ocean waters) are unsuitable for turbid coastal and inland waters. we tried to build up a simple model for com puting the spectra of rd with the aim of estimating the efficiency of the similarity method on the basis of our remote sensing data. we assumed that there are only three optically active substances in the water: chlorophyll a, yellow substance and hydrosol. under these conditions the total spec tral absorption coefficient of the water, aa, is described by the following formula: aa = aw.y + achl.acchl + ay.acy -k ah.ach, (4) where is the spectral absorption coefficient of pure water; achlj, ay.a, a h s a are respectively the spectral specific absorption coefficients of chloro 6 h. arst & t . kutser phyll, yellow substance and hydrosol; and cchi, c, and ch are their respective concentrations in the water. the values of aw,ar aehl,a and ah,a were obtained from plass, humphreys & kattawar (1978) (from which cchl values are obtained in mg/m3, but ch values only in relative units). the values of a,,* were calculated by the formula, taken from topliss, miller & irvin (1989): a,,l= 0.565exp[-y(a380)], (5) where y = 0.013 2 0.005, ais given in nm, and aya in l.mg-’.m-’. the values of c, will be in mg/l. the total spectral backscattering coefficient, b! is given by b i = + &.&hch, (6) where bw,* is the spectral scattering coefficient of the pure water and bh is the specific scattering coefficient of hydrosol. is the ratio of the hydrosol backscattering coefficient to its scat tering coefficient. the values of bh and were estimated from physical models of scattering properties of the seawater by kopelevich (1983). on the basis of the values of aa and b! we can determine the gordon’s parameter xa (gordon, brown & jacobs 1975): b! x* = al + b i ’ (7) which is used in the formulae to calculate the diffuse reflectance of the sea just below (z = -0) and just above (z = +0) the water surface. from gordon, brown & jacobs (1975): rd(z = -0) = 0.0003 + 0.3687x + 0.1802x2 + 0.0740x3, (8) rd(z = +0) = 0.179x + 0.051x2 + 0.171-x3. here one can see that (9) rd(z = +o) 0.5rd(z = -o), (10) (see also arst, pozdnyakov & rozenstein 1990). an alternative formula for computing rd(z = -0) is presented by kirk (1989): b* a rd(z = -0) = (0.975 0.629h)-, (11) where p,, is the cosine of the direct solar beam in the water (after refraction). taking into account formula (10) we get: using formulae (4)-(6) and (12) a program was developed to calculate the model spectra of rd and compare these with the measured spectra. naturally, we did not expect to get the 100% coincidence, because our model is not ideal and the absolutely correct experimental spectra are unreal. for this reason we considered in each case ten “model” spectra, most similar to the experimental one. results and discussion to estimate the efficiency of any method for the interpretation of remote sensing data, sim ultaneous remote and in situ measurements must be carried out. after data-processing one can compare the results obtained from the water samples with those from the remote sensing method. since 1981 we have made several expeditions in the baltic sea and in estonian lakes at which telespectrometrical and in situ measure ments were carried out mainly on board a ship. considering the correlation method, we have investigated the appropriateness of 20 spectral and 6 integral characteristics for the interpretation of remote measurement data (arst, eerme & purga 1984; arst et al. 1989; arst et al. 1990; kutser et al. 1993). using correlative relation ships between these characteristics and the results of in situ measurements in the waterbody, we have determined several algorithms to compute the relative (secchi disk) transparency and the chlorophyll a concentration in the water from the telespectrometrical data. as an example of these results we present the algorithm for the chlorophyll concentration (&) using data obtained from the gotland deep poly gon (in the baltic sea) in summer 1989 (cor responding correlation coefficient r = 0.84): here c,-hi = 5.2y 1.53. (13) 455 690 i,,, rd(a) da rd(a) dl [rd(a) da y = 1 (14) data processing and interpretation of sea radiance factor measurements 7 where the bounds of the integrals are the wave lengths of light in nm. the isolines of the chlorophyll concentrations measured and calculated by formula (13) are shown in fig. 1. these isolines match rather well. however, our investigations in other regions of the baltic give different results. for instance, in the polygons of the gulf of finland the chloro phyll concentration has a poor correlation (r = 0.33) with y , but a good correlation (r = 0.72 0.82) with several other characteristics of the remote sensing spectra (mostly with the spectral differences of radiance factor). similar results were obtained from the largest estonian lake, lake peipsi. in fig. 2 the isolines of the secchi disk transparency (sd), determined by remote sensing and in situ methods from an 56' 1 19' 20' e fig. 1. estimation of the chlorophyll a concentration by tele spectrometric measurements in a polygon at gotland deep (baltic sea) 30 june-1 july 1989. solid and dashed lines indicate respectively the cchl isolines, measured in situ and computed using formulae (13) and (14). fig. 2. isolines of the secchi disc depth in lake peipsi on 13 june 1987 measured in situ (a) and calculated from remote sensing results (b) using formulae (15) and (16). the cor responding correlation coefficient is 0.96. expedition in june 1987 are presented. the cor responding algorithm is sd = 16.4w(lu) + 0.45. (15) here and l,(a) is the value of the upwelling radiance at the wavelength of light a (direction of measure ments is to nadir, a is in nm). however, a good fit between the remote sens ing data and the in situ measurements, such as fig. 2, can be obtained only by relying on the results of a single expedition. our attempts to determine a general algorithm, using the whole data set (for lake peipsi there were four expeditions in different weather conditions) were unsuccessful. neither did we succeed in finding among the whole range of characteristics of the remote sensing spectra a single preferred charac teristic for describing water quality. though undeniably there do exist connections between the optical remote sensing data and several sub stances in the water, it seems there is no universal algorithm determined by the correlation method, which can describe these connections for different water bodies and in different weather conditions. this conclusion is supported by the results of other researchers (hejerslev & jerlov 1977; buttner & voros 1981; aarup et al. 1990; bukata et al. 1991; mitchell & holm-hansen 1991). 8 h. arst & t . kutser an attempt to estimate the efficiency of the similarity method was made using telespectro metric data and simultaneously measured chloro phyll concentrations from 87 sampling stations in the baltic sea and some estonian lakes. the measured chlorophyll a concentration varied between 0.3 and 47 mg/m3. unfortunately we were not able to obtain values of c, and ch. however, the results obtained are quite inter esting. it appears that the divergence of the values of c, and ch corresponding to the ten “most similar” theoretical spectra is relatively small (there are several combinations of cchi, c, and ch for which some numerical values are identical and some differ by not more than one or two grid steps in the values put into the model). conse quently, we obtain rather stable final results by averaging these ten values. it is worth noting that in most cases the best results give the normalized spectra (in our calculations the normalizing wave length is 520 nm). the correlation coefficient between the com puted and measured chlorophyll concentration values is 0.82. if the measured cchl is between 0.3 and 4 mg/m3, the corresponding computed cchl is between the same limits, but the relative error is often high. here the influence of chlorophyll on the radiance factor spectra is often screened by the stronger influence of the yellow substance and hydrosol, which have high concentrations in turbid waters. as a rule, the relative difference between measured and calculated cchl values decreases with increasing chlorophyll concen tration. for the whole data set, the computed values of yellow substance and hydrosol con centrations vary from 0.1 to 16 mg/l and from 1 to 40 correspondingly. in fig. 3 two examples of the r d spectra obtained from telespectrometrical measure ments, and the corresponding “most similar” model spectra, are shown. note that we took these results from the group of spectra which gave very good coincidence between the measured and calculated chlorophyll concentrations. we had no telespectrometrical data for the waters of the cold regions (including the arctic and antarctic). however, one can assume that in these waters the yellow substance and hydrosol concentrations are significantly lower than in the lakes and coastal waters in moderate latitudes. we made computations using the similarity model for underwater data (the values of c~ = aa + ba are necessary) from moderate and cold regions. r b i i i i i 0 500 600 & n m fig. 3. comparison of the rdn (normalized rd) spectra obtained on the basis of the telespectrometrical measurements (solid curves) with those determined as the “most similar” by model calculations (dashed curves): a. the baltic sea, near bornholm island, 27 july 1981; b. estonia, lake peipsi, 14 august 1990. the ccm values determined from water samples arc respectively 2.2 and 8.7mg/m3, the “modcl spectra” give the following results: c,h, = 2.0 mg/mi, c, = 0.4 mg/l (bornholm waters) and c c h , = 7.3, c, = 12.0 (lake peipsi). in the first case the values of ca, determined by us for parnu bay in april 1993, were used. in the second case we used the data by matsuike, nakamura & hago (1979) for the bering sea in july and august. unfortunately, in this paper only data on the irradiance attenuation coef ficients were presented and we had to determine the necessary values of aa using the formula by kirk (1989) describing the relationship between data processing and interpretation of sea radiance factor measurements 9 absorption coefficient, scattering coefficient and irradiance attenuation coefficient. the spectral values of the scattering coefficient we took from the data of scattering model 2 by kopelevich (1983) (scattering coefficient at 400 nm is 0.087m-' and decreases down to 0.049111-') at 680nm. some examples of the results of these calculations are presented in table 1. as expected, the concentrations of optically active substances in the highly turbid waters of parnu bay significantly exceed those in the bering sea. for parnu bay we have also determined the cor responding values of chlorophyll and yellow sub stance concentrations from water samples. these values are mostly close to those calculated on the basis of beam attenuation coefficient spectra. as mentioned above there are difficulties of deter mining the cchl values in turbid waters, containing high amount of yellow substance. obviously this is the reason for the comparatively poor coinci dence of the cchl values at parnu bay station 9. table 1. values of the irrddiancc attenuation coefficient (in m i ) for stations 4 and 1 1 in the bering sea (data taken from matsuike et al. 1979), the beam attenuation coefficient (in m-!) for stations 9 and 1 1 in the plrnu bay (our measurements in april 1993) and concentrations of cchl (in mg/m'), c, (in mg/l) and ch (in relative units) calculated on the basis of these spectra. for parnu bay the corresponding values c,,, and c,, determined from water samples, are also shown. bering sea parnu bay a, nm st. 4 st. 11 b, nm st. 9 st. 1 1 375 0.16 0.36 400 12.32 9.40 427 0.14 0.39 420 10.22 8.49 484 0.078 0.30 450 7.89 1.33 513 0.098 0.24 480 6.60 6.68 572 0.13 0.17 500 5.89 6.32 622 0.38 0.39 520 5.52 6.10 650 0.42 0.49 550 5.05 5.94 681 0.53 0.54 580 4.84 5.67 60 4.64 5.59 650 4.31 5.52 ~ ~ calculated from underwater optical data cchl o.3 1.2 8 4 c, 0.1 0 . 2 18 7 c" 1.0 4.5 70 65 measured from water samples cchl 12.4 5.2 19.5 8.2 c, the tests for estimating the efficiency of the similarity method indubitably need to be con tinued using additional (and larger) data sets and an improved computation model. however, our preliminary results show that this method is quite promising. detection of oil-slick pollution on the sea surface the spectra of the radiation factor component r r ( a ) , obtained from passive optical remote measurements enable the detection of oil-slick pollution on the water surface (arst, pozdnyakov & rozenstein 1990). as is well known, the light reflection coefficient of the oil exceeds that of the water; for that reason one can expect a positive contrast between rr(oil) and rr(water). at the same time the oil-slick pollution changes the sur face wave characteristics. for the latter reason the contrast between the rr values for pure and oil-polluted sea surfaces depends on the measure ment direction, solar zenith angle, wind speed and direction, angle between wind direction and sun's azimuth. the model computations on the basis of formulae, taken from arst, pozdnyakov & rosenstein (1990), show that under conditions of an undulating sea surface, "abnormal" con trasts may occur in which the r r values for the pure water surface exceed the corresponding rr values for the oil-polluted sea surface. some examples of the dependence of r r on wind velocity for the cases of polluted and clean sea surfaces, and observations at nadir, are shown in fig. 4. as one may see the variability of the positive and negative values of the difference l h r = rr(oi1) rr(water) depends on the solar zenith angle. computations of f k r for several measure ment directions show that the character of its variability is rather irregular. the influence of the oil-slick on the rr values is most conveniently demonstrated by means of the contrast k = atr/ rr(water). some examples of the variability of this contrast for light and heavy baku oil are shown in fig. 5. as one may see, for wind speed 5m/s, solar zenith angle 30' and measurement direction t o nadir, k is negative and its absolute value is small; oil-slick detection is easiest when the nadir angle is about 15-45' and the azimuth of measurement is 180". but in the case 8,, > 60' (typical for the northern seas) and wind velocity 10 h . a n t & t. kutser "r 0.0 5 0 5 10 15w,m/s 0.1 0.0 2 0.0 0 5 0 5 d 15 w,m/s k 2 1 .i 1 0.t c q! 1 10 20 50 40 0 "m 10 20 50 40 0.0 0 5 0.00 2 0.0 0 1 0 5 10 l5w.m fig. 4. dependence of the component rr on the wind velocity (w) and the solar zenith angle (19,) for a slick of heavy baku oil (dashed curves) and pure water (solid curves). the thickness of the oil slick is 50 pm, the wavelength of light 720 nm, the measurement direction is to nadir, the azimuth of wind and the sun are the same. 1 4 0 10 20 90 40 50 i "m 10 20 50 40 50 fig. 5. dependence of the contrast k o n the measurement direction (azimuth % and zenith angle 8,) and solar zenith angle 4 (wind velocity 5 m/s, wind direction % = 45". sun's azimuth q,, = 0") for wavelength of light 510 nm and oil slick thickness 50 pm. the values of % are shown by the following: 0" (wed square), 60' (plus), 120" (asterisk) and 180" (empty square). a, c, d = heavy baku oil, 19, is 30", 60" and 80". respectively; b = light baku oil, bo is w. w < 7 m/s, measurement directions near to nadir are most suitable for the detection of the oil slick on the sea. here the further increase of the wind velocity causes a decrease of arr (through zero to negative values). however, under conditions of strong wind the oil slick is usually torn and the determination of the contribution of oil to the rr values is complicated. note that due to light interference phenomena in the oil-slick the curves of rr and k often have an oscillating character (for example, the curves for light baku oil in fig. 5 ) . the period and data processing and interpretation of sea radiance factor measurements 11 amplitude of this oscillation depend on the wave length of light, the thickness of the oil slick and on the type of oil. in the case of oscillations within a small period, the grid step in the computation procedure must be very small, otherwise the shape of the r r (or k) curves cannot be accurately described. conclusions the main conclusions of the preliminary inves tigations of two methods for the interpretation of passive optical remote sensing data are charted below. both the methods under consideration need accurate telespectrometrical data. here, as was mentioned above, the main source of instability is the influence of sun glint on the values of r r ( a ) . to avoid this, a suitable measurement direction must be chosen; however, in many cases the nadir direction is technically the most suitable. in this case measurements in conditions of great solar zenith angles guarantees that the results are free from the influence of sun glint, but in these con ditions the solar radiation reflected from the nadir point is small and an apparatus with high sen sitivity is required. it is quite possible to detect oil-slick pollution using passive optical remote sensing method, but because of the instability of the contrast between rr(oil) and rr(water) the interpretation of the results has t o be performed by numerical model ling. acknow/edgemena. the authors express their gratitude to t. miller and l . kaarmann for their help in carrying out the work. comparison of the correlation and similarity methods method positive negative correlation method, where correlative relationships between the spectra of r(a) (or rd(a)) and concentrations of optically active substances in water are determined and corresponding regression formulae found. similarity method, where the spectra of r(a) (or rd(a)) are compared with the multitude of spectra obtained from model calculations to find the theoretical spectrum which is closest to experimental. it is assumed that the concentrations of substances used for computing the theoretical spectrum are the same for the experimental spectrum. no need to describe the water environment by a theoretical model, o n l y experimental data for the determination of the regression formulae are necessary. the parameters of the regression formulae depend on the location, season and weather conditions. not general. considerably more general than there are difficulties in the the correlation method. if the detailed description of the theoretical model is successful, absorbing and scattering the similarity method works properties of all the optically everywhere. active substances, especially the type, size distribution and backscattering properties of suspended matter in the computation model. 12 h . arst & t . kutser references aarup, t . , groom, s. & holligan, p. m. 1990: the processing and interpretation of north sea czcs imagery. netherlands j . sea res. 25, 3-9. afonin, e. & kravtsov, g. 1986 modern apparatus and methods of the ocean and atmosphere in visible part of light spectrum. sevastopol. 75 pp. (in russian). arst, h., eerme, k. & purga, a. 1984: on the brightness coefficient of the baltic sea. deutsche hydrogr. zeitschr. 37 arst, h., miller, t., torp, t., lukk, t. & meitern, j . 1989: estimation of the transparency of the baltic sea waters and estonian lakes by optical remote measurements. proc. 16fh conf. balfic oceanographers, k i d , 711-716. arst, h . , kaarmann, l., miller, t.. torp, t. & kutser, t. 1990: estimation of the baltic sea water quality by optical remote measurements. abstracts 17th conf. baltic ocean ographers, norrkoping, sweden. arst, h., pozdnyakov, d. & rozenstein. a. 1990: optical remote sensing in oceanography. valgus, tallinn. 444 pp. (in russian). biittner, 0. & voros, l. 1981: investigation of hungarian lakes by means of landsat data. adv. space. res. i , 177-189. bukata, r . p., jerome, j . h . , kondratyev, k. y. & pozdnyakov, d. v. 1991: satellite monitoring of optically active components of inland waters: an essential input to regional climate change impact studies. j. greaf lakes r e f . 17, 470-478. carder, k. l., hawes, s. k., baker, k. a , , smith, r. c., steward, r. g. & mitchell, b. g . 1991: reflectance model for quantifying chlorophyll a in the presence of productivity degradation products. j. geophys. res. 96 ( c l l ) , 20,599 20,611. ( h 6 ) . 221-233. gordon, h. r., brown, 0. b. &jacobs, m. m. 1975: computed relationships between the inherent and apparent optical properties of a flat homogenous ocean. appl. o p f . 14, 417 427. h ~ j e r s l e v , n. & jerlov, n. 1977: the use of the color index for determining quanta irradiance in the sea. rep. inst. phys. oceanogr., copenhagen university, no. 35. 12 pp. kirk, j. t. 0. 1989: the assessment and prediction of optical water quality. australian wafer and wasfewafer associafion 13th federal conuenfion, 504-507. kopelevich, 0 . v. 1983: few-parameter model of the optical properties of the seawater. pp. 208-235 in monin, a. s. (ed.): opfics of the ocean, vol. i . nauka, moscow (in russian). kutser, t., arst, h., miller, t . , kaarmann, l. & milius a . 1993: telespectrometrical estimation of water transparency, chlorophyll a and total phosphorus concentrations on lake peipsi (in press). lokk, j . & purga, a . 1982: water quality study of the baltic sea by optical remote sensing methods. pp. 523-530 in hydro dynamics of semienclosed seas. amsterdam, elsevier. mitchell, b. g . & holmhansen, 0. 1991: bio-optical proper ties of antarctic peninsula waters: differentiation from tem perate ocean models. deep-sea res. 38, 1g€l9-1028. matsuike, k., nakamura, y. & haga, m. 1979: aerial and submarine spectral solar energy distributions and optical characteristics of the waters in the bering sea during the summer. la mer 17, 1-10, plass, g . n., humphreys, t. j . & kattawar, g. w. 1978: color of the ocean. appl. opt. 17, 1432-1446. shifrin, k. s. 1983: introduction fo ocean optics. gid rometeoizdat, leningrad. 278 pp. (in russian). topliss, g. n., miller, j . r. & irvin, b. 1989: ocean optical measurements 1. statistical analysis of data from the western north atlantic. confin. shelf res. 9 , 113-131. por_019.fm polar research 26 2007 181 – 194 © 2007 the author 181 blackwell publishing incmalden, usaporpolar research0800-03952007 blackwell publishing ltd? 2007262181194original article a cursed affairf. skarstein h i s to r i c a l / b i o g r a p h i c a l e s s ay “a cursed affair”—how a norwegian expedition to greenland became the usa’s first maritime capture in world war ii frode skarstein norwegian polar institute, polar environmental centre, no-9026 tromsø, norway last year, frode skarstein contributed an essay to polar research in which he related the failed attempt by a coterie of nationalistic norwegians to annex part of greenland— “erik the red’s land”—for norway during the early 1930s. in the following essay, skarstein tells the story of how the same group of norwegian nationalists tried to resurrect norwegian claims to the east coast of greenland during the second world war—and how the colliding interests of the germans and the americans made for a dramatic finale to the norwegian adventures in erik the red’s land. —the editor keywords greenland; arctic imperialism; adolf hoel; world war ii; hallvard devold; norway. in the fall of 1941 a norwegian ship left germanoccupied northern norway bound for greenland. the buskø was loaded with supplies for the norwegian trappers who, as in previous years, were overwintering on greenland’s east coast. organized by norway’s svalbard and arctic ocean research survey, the precursor to today’s norwegian polar institute, these expeditions had developed into a yearly event. hallvard devold, the man heading the expedition in 1941, was the same man who, 10 years earlier, had done the dirty work in a wrestle with denmark over eastern greenland (skarstein 2006). almost three months ahead of japan’s surprise attack on pearl harbor, which precipitated the usa’s formal involvement in world war ii (wwii), the us coast guard seized and brought the buskø and all onboard to boston for interrogations. a remote and strategically unimportant place, greenland had suddenly become an arena for the first encounters between us and german forces during wwii. a ship is coming! 8 th of september,—a ship is coming! . . . i’m restless, rushing back and forth, the cabin is whipped into perfect order, preparing to receive guests . . . so they’re still sending ships from norway—they haven’t forgotten us. the emotional turmoil is overwhelming. it is ss buskø of ålesund. (sørensen 1958: 211–212; this and all other translations from norwegian are by the author) with these lines, the legendary norwegian trapper henry rudi describes the scene when, after a long and lonely winter and summer, he realizes that he’s not forgotten on the barren strip of land between the enormous ice cap of greenland and the vast north atlantic, where the norwegian trapping station of moskusheimen was located (fig. 1). he had left norway with a trapping expedition in the spring of 1939, before the germans had overrun norway and denmark. during the winter of 1940/41 and the summer of 1941, he had had only sporadic contact with the handful of danish trappers who inhabited all of north-eastern greenland. the trapping season had been lousy, and after his radio batteries ran out he had virtually no information on how norway was faring in the war, or whether he would be receiving essential supplies that year. the arrival of the buskø and the supplies she carried was a great relief for rudi, whose narrative goes on to explain that the ship had already dropped off five men north of moskusheimen. in order to move some of their equipment further south, rudi and his new partner gerhard anthonsen, who had come on the buskø , travelled on the ship southwards along her planned supply journey to myggbukta, humboldt, and finally the southernmost norwegian trapping station at antarctichamn. however, shortly after being dropped off from the buskø , presumably in a smaller boat, rudi recounts how they were boarded by the us coast guard cutter (uscgc) northland , on patrol in the area (sørensen 1958: 212). acting on orders to evacuate all the trappers in east greenland, the northland had already seized the buskø and detained everyone onboard. rudi, in his 52nd year, managed to correspondence norwegian polar institute, polar environmental centre, no-9026 tromsø, norway. e-mail: skarstein@npolar.no. doi:10.1111/j.1751-8369.2007.00019.x 182 polar research 26 2007 181 – 194 © 2007 the author a cursed affair f. skarstein convince the “calm and polite, firm and clear” captain of the northland , commander c. c. von paulsen, to let him stay in greenland (sørensen 1958: 212). thus, a few days later, rudi is again alone on the beach at moskusheimen as the northland steams off and disappears. the war, however, would soon catch up with him again. within a year, as the conflict in greenland between the germans and the allies escalated, rudi joined the danish-controlled sledge patrol that formed after the us initiative (odsbjerg 1990). a relief expedition on 9 april 1940, the second world war came to norway and denmark with the german occupation forces. at that time arktisk næringsdrift (arctic commercial enterprises), the main norwegian company involved with trapping in north-east greenland, and norges svalbardog ishavsundersøkelser (nsiu—norway’s svalbard and arctic ocean research survey, which, in 1948, became the norwegian polar institute) were involved in trapping and weather-reporting activities in north-east greenland. divided between the areas of south-east and north-east greenland (fig. 1), about a dozen trappers had overwintered in small hunting stations scattered across the vast territory, in addition to a telegraphist and a scientist. one of the trappers had also brought his wife, who had given birth during the winter. very few private boats left norway after the german occupation. the german occupation force was annoyed by the dribble of smaller vessels that slipped away into the north sea towards great britain, and consequently imposed strict regulations on the movements of any vessel with long-range abilities. however, during the summer of 1940 the nsiu managed, with an odd combination of permissions from the german-installed norwegian government in oslo, and the fleeing norwegian government in tromsø, northern norway, which was still free at that time, to arrange for two ships—the veslekari and the ringsel —to relieve the norwegians in east greenland. off the coast of east greenland the norwegian inspection vessel fridtjof nansen , now in the allied coastal patrol service, intercepted the veslekari . the crew was brought to england under suspicions of german association with the expedition. (the expedition leader, john giæver, later managed to get to the usa, working for the norwegian authorities there; he makes an entry in the buskø story below.) the trappers that had overwintered were given fig. 1 map of greenland showing the most important places, events and vessel movements mentioned in the text. f. skarstein a cursed affair polar research 26 2007 181 – 194 © 2007 the author 183 the choice of staying on or being evacuated. six trappers were then removed to iceland. unaffected by these events, the ringsel made a smooth return trip to norway, despite having run into the uscgc northland in southeast greenland earlier. thus, when the spring of 1941 thawed the poor trapping winter of 1940/41, there were seven trappers in north-east greenland, some of whom had been there for three years. the relief of these was the immediate and obvious explanation for the 1941 expedition with the buskø . a more veiled and long-term goal was to maintain norwegian trappers in east greenland, in line with the arctic expansion dream that flowed as an undertow of most of the activities of both arktisk næringsdrift and the nsiu. the ruling of the permanent international court of justice in the hague in 1933 against the norwegian occupation of the large territory of eric the red’s land, in east greenland, had killed public interest in the greenland issue in norway, and had halted to any concrete plans for norwegian expansion in east greenland (blom 1973; skarstein 2006). however, the effective and wellcoordinated twosome that masterminded the occupations in the 1930s, adolf hoel (an influential norwegian geologist who was head of the nsiu; fig. 2) and gustav smedal (a nationalistic lawyer with a strong interest in norwegian polar expansion), saw in the german invasion of denmark and norway a window of opportunity to regain the lost norwegian “colonies in the east”. at the same time, the war had brought greenland into the focus of the usa. in cooperation with the now isolated danish governor of greenland, the us coast guard had secured the west coast and was patrolling sections of greenland’s eastern coast, inspecting and interfering with the activities of nsiu and arktisk næringsdrift. hoel and smedal felt that if no interest was shown from the norwegian government in supporting the trappers and maintaining a norwegian presence in greenland, the changing geopolitical picture would make the usa move to grasp the island (hoel 1977). the usa did indeed appear to shift in its interpretation of the political and security role of greenland to make it fall within its sphere of interest (stordalmo 2006). this meant that the usa could invoke its monroe doctrine from the 1920s and label any german or german-influenced establishment in greenland as hostility against the usa’s direct sphere of interest. consequently, american involvement and cooperation with the danes in greenland was seen by the duo hoel and smedal as not only an overhanging threat to norway’s interests in east greenland, but as a threat to the whole idea of greenland belonging to europe rather than to the new world. a year into the german occupation of norway hoel and smedal were attempting to influence the germans into direct action regarding the greenland issue. the germans, however, showed little interest in the idea of norwegian arctic imperialism, and the arctic expansion enthusiasts turned again to the strategy of 10 years previously: to claim the land through subsidized use and exploration. thus, in the eyes of adolf hoel, gustav smedal and the nsiu, the maintenance of norwegian trapping activity in east greenland was essential in maintaining norwegian possessions and rights in the arctic (hoel 1977). with the nsiu’s meteorological stations in east greenland put out of function by allied forces in 1940, the immediate purpose of a 1941 expedition would be to supply and relieve the trappers at the trapping stations. to ensure that their plans were not lost at some low bureaucratic level, hoel wrote directly to vidkun quisling, head of the puppet government in norway. initially quisling, who had previously managed to get hoel to join the nasjonal samling (ns)—the norwegian nazi party— by promising to put the greenland issue on the party programme, had visions of a huge expedition of 100 trappers and several vessels. however, it was decided that 100 trappers could not be mustered at such short notice, but the expansion enthusiasts believed that they could assemble a group of 50 trappers for the coming season. this plan was rejected by the department of commerce and the german authorities (stordalmo 2006). seen against the backdrop of the previous capture of the veslekari and the us involvement in greenland, the rejection did not come as a surprise. in the beginning of august fig. 2 this picture of adolf hoel (1879–1964), on the right, was probably taken in the late 1930s. as a geologist, hoel had carried out pioneering research in svalbard during the early 1900s, and was the main driving force behind the establishment, in 1928, of norges svalbardog ishavsundersøkelser (nsiu), the forerunner of the norwegian polar institute. (courtesy norwegian polar institute picture library.) 184 polar research 26 2007 181 – 194 © 2007 the author a cursed affair f. skarstein 1941 an agreement was reached between arktisk næringsdrift and the ministry of commerce on a more modest plan of 10 trappers and one vessel. this relief expedition even received a significant grant from the department of commerce (barr 2003). initially, each of the manned stations was supposed to have a radio set for communications between the stations. however, the ministry insisted that no land-based radio transmitter should be brought along, as this would increase the risk of british or american intervention. this was formalized in a written agreement between the ministry and arktisk næringsdrift. furthermore, the whole expedition was to be kept as secret as possible to avoid any information reaching the allied forces. enter the buskø with a definite go from the norwegian administration in oslo, hoel immediately went into motion and, after having called around several companies, arranged for the steam-powered sealer buskø of ålesund, norway, to be chartered for the expedition (fig. 3). she was owned by the shipping entrepreneur elling aarseth, who also owned the veslekari , already captured and now in allied service in the western atlantic. built in 1926, equipped with a 140-h.p. steam engine from 1902, and measuring 105 ft, the buskø was the largest vessel available for rent at the time. the name stems from the island buskøya at the mouth of the fjord sognefjorden, the home area of the first owner jan hess. the buskø was officially chartered by arktisk næringsdrift, and in the contract between the company and the owners of the buskø the purpose of the expedition was stated to be “explorations of a scientific nature and to bring new overwinterers and fresh supplies to norwegian stations and/or to bring trappers, catch and equipment home” (state archives). the experienced trapper hallvard devold was hired as the expedition leader (fig. 4). he had been temporarily employed as secretary at nsiu after john giæver failed to return on the 1940 relief expedition to greenland. devold had previously played a central role in the tussle over eric the red’s land in 1931 as head of the expedition that carried out the private annexation of the area, an action that eventually forced the norwegian government into following suit by occupying the territory (blom 1973; barr 2003; skarstein 2006). during the planning of the expedition, adolf hoel was asked several times to report on it to a certain obersturmführer hermann krause from the german security police. during several meetings, krause asked for information on all aspects of the expedition, including the backgrounds of the crew and trappers. the buskø left ålesund on 18 august 1941 with hallvard devold onboard, hugging the norwegian coast northwards towards the norwegian port of laukvik, senja, before it turned west to cross the north atlantic. during the trip northwards, the buskø would have several stops to take onboard crew and equipment. before the departure from ålesund, devold had sent off a telegram to hoel that read: “if of interest, convey to krause that the participants will be joining the boat in namsos, sannessjøen and laukvik—devold” (norwegian state archives). fig. 3 the sealer buskø in the sealing grounds off eastern greenland in the early 1950s. (courtesy of ishavsmuseet, brandal, norway.) fig. 4 hallvard devold, the leader of the 1941 norges svalbardog ishavsundersøkelser (nsiu) relief expedition to eastern greenland. the picture was taken in laukvik, senja, northern norway, just before departure from norway to greenland. four years would pass before he could return to norway. (courtesy of the norwegian polar institute picture library.) f. skarstein a cursed affair polar research 26 2007 181 – 194 © 2007 the author 185 this telegram, as he would later explain, was sent because he had the impression that krause wanted to inspect the crew and expedition members, as he assumed this was the reason krause was involved in the whole business. in devold’s words: already ahead of my departure from oslo i was told that krause would travel to ålesund and inspect the expedition prior to departure. as it appeared so important to clarify which people would be joining the expedition i thought the purpose of his travel would be to gain an impression of the expedition members and possibly arrange for our departure papers. (norwegian state archives) krause however, never appeared in ålesund, and devold was told to go to the harbour office to confer with the german harbour commander there. he was interviewed for a full day about the purpose of the expedition, something he had to repeat several times as new german officers came into the room. as a confusing end to the day, the raring-to-go devold had to garner more patience, as the germans took him off for a social evening with a cinema visit and dinner. the following day, krause still failed to materialize in ålesund, and devold sent the aforementioned telegram, a telegram he later realized could appear to indicate that he wanted the germans to know where they could reach the ship. the buskø arrived in laukvik on 28 august 1941. this was its point of departure from norway across the atlantic towards greenland. the same day obersturmführer krause arrived in a fishing vessel from tromsø, a city to the north, under the pretext of inspecting the buskø and the crew. however, it soon became clear that the visit had a more sinister purpose. he insisted that the boat bring along a land-based radio set and a radio operator to petersbay in greenland, where two of the expedition’s trappers were already supposed to be based. the ship’s captain and in particular the engine operator protested, and during a heated exchange with krause the engine operator hinted that the buskø might just not return. krause dryly replied, “[w]e have long arms, we have both submarines and planes, and you have a family at home” (simonsen 1941a). the same day the captain and the engine operator sent a co-signed telegram to the owner of the buskø , elling aarseth, which he received only after the buskø ’s departure. i hereby take the liberty to convey that we in laukvik have gotten onboard an extra man, from the german wehrmacht, purportedly a radio operator, meteorological observer. this is outside of the contract and i am communicating this for the record. nevertheless, i will complete my mission in accordance with ability and agreement. we depart from laukvik at 4 am on august the 29 th . sincerely, elias hessen & petrus ekrem. (norwegian state archives) later, devold would recollect that during the trip northwards along the norwegian coast with the buskø , at a stop in harstad, he had had a telephone conversation with adolf hoel. sounding very disappointed, hoel explained that an extra man would join the expedition. when devold asked if it was a norwegian or a german, hoel replied, “it appears to be a norwegian by the name of bradley” (simonsen 1941a). the agent a 1945 publication of the nsiu lists the members and collaborators of the expeditions sent out by nsiu in the period 1937–1941 (fig. 5). one entry reads: “bradley, jacob [sic]. wireless operator north-east greenland 1941”. this was the man the german officials forced the buskø to take with them from laukvik. iakob bradley grew up in bergen, norway, and was, at the time of the fig. 5 iakob bradley and hallvard devold appear in a list of participants of norges svalbardog ishavsundersøkelser (nsiu) expeditions between 1937 and 1941, which was published in the nsiu’s series skrifter (p. 88) in 1945. 186 polar research 26 2007 181 – 194 © 2007 the author a cursed affair f. skarstein german attack on norway, 25 years old and a member of the ns in bergen (fig. 6). he had by this time climbed to the rank of sveitfører (the equivalent of captain) in the hird, the ns party’s militia, which put him in charge of approximately 120 men (pryser 2001). according to bradley himself, his duties were mostly that of propaganda and drafting. following disagreements with a german advisor to the local ns party, bradley resigned this position during the fall of 1940 and, during the spring of 1941, he let his membership in the ns expire (simonsen 1941a). nevertheless, he had developed connections with several germans, in particular civilians in the german nazi party. thus, despite considering himself as having left the ns, he kept in touch with the nazi movement through social connections with nazi party members and visits to the local ns office (simonsen 1941a). this contact with the norwegian ns, his german nazi connections and his experience at sea were probably the reasons why, around the middle of august 1941, bradley received a phone call from a certain weiler in the german security police in norway. weiler informed him that plans for an expedition to greenland were being developed, and asked him if he wanted to join as a meteorologist and radio operator. bradley requested more information, but was told that he had to travel to oslo for a full briefing on the matter. weiler simply gave him a train ticket, and the next day the 26-year-old was on a train to oslo. over four decades would pass before he saw bergen again. arriving in oslo he walked directly from the railway station to the german gestapo headquarters in victoria terrasse. he spent the next five days in oslo being trained in basic meteorology and radio operation. the training took place in a “private house” (simonsen 1941a) between 08:00 and 19:00, and his teachers spoke only german. from bradley’s experience at sea, he had acquired a sufficient understanding of german to understand the instructions he got. the crux of his activities in greenland was to collect simple weather observations at 05:00, 08:00, 12:00 and 19:00 every day, and to relay them to the germans in one of the simplest cryptography codes available. he received a small-calibre pistol with 40–50 shots. six days after first being contacted by the germans, he was on a seaplane northwards to meet up with the buskø . the plane landed in tromsø, where he spent two days, amongst other things, assembling some clothes for the overwintering, as he had not had time to pack anything upon his departure from bergen. in the early hours of 29 august, he left tromsø and arrived in laukvik where the buskø ’s crew was recovering from a wet departure party. the german plan on 20 august, two days after the buskø left ålesund heading northwards to laukvik, hoel was told to meet with krause again. during this meeting he was informed that the german luftwaffe would send a radio station and a telegraphist with the expedition. hoel warned that this might jeopardize the whole endeavour, as the allies would then perceive the expedition as being a german initiative. furthermore, hoel pointed out that the germancontrolled ministry of commerce had strongly advised against this. krause brushed all these protests aside, claiming that this was “an affair that entailed only german responsibility” (stordalmo 2006). in an effort to cover his back, the following day hoel sent a letter to krause spelling out his protest, again referring to the agreement with the ministry of trade that no land-based radio station would be taken onboard the buskø . krause, however, simply failed to reply. on 25 august krause contacted hoel, who was told the identity of the telegraphist who would accompany the buskø . as a result of a misunderstanding, hoel thought the telegraphist was a previous acquaintance of fig. 6 iakob rytter bradley presenting the bergen hird force to the german-installed minister president vidkun quisling some time during the fall of 1940. bradley claims to have left the hird forces and the nasjonal samling shortly afterward. bradley is in front of the uniformed lines, directly facing quisling, who is wearing an overcoat. (courtesy of norgeslexi online picture archive.) f. skarstein a cursed affair polar research 26 2007 181 – 194 © 2007 the author 187 dubious reputation. hoel’s version of the telephone conversation he had with devold in harstad was that he wanted to warn devold to be alert against this man. arrival in greenland after the radio equipment and bradley were installed onboard the buskø , the vessel left laukvik and norway on the morning of 29 august and headed out across the atlantic. the crew accepted bradley without open hostility, although a definite coolness was present, manifest in the fact that he was not assigned a place to sleep, and that few members of the expedition would later admit to having talked to him during the crossing. krause had instructed that the suitcases that held the radio equipment were to be stored on deck for easy dumping overboard in case us or allied forces intercepted the vessel. as the days passed and bradley realized that none of the crew had any idea of his or the german involvement in the expedition until just before the departure, he expressed feeling betrayed. during his training in oslo he had asked to meet with hoel and the nsiu, but the germans had claimed that there was no time and that everything had been taken care of with the nsiu. thus, bradley, realizing this was a somewhat shadowy affair, would later express that he regretted having agreed to come along (simonsen 1941a). the crossing of the atlantic went smoothly, and by 2 september the buskø was through the belt of drift ice that pours out of the arctic basin through fram strait and down along the east coast of greenland. she touched land and immediately went north to petersbay, and on 4 september, bradley, together with two trappers and all their goods, provisions and meteorological and radio equipment, were dropped off. a weight must have been lifted from devold’s shoulders. however, his relief would last only a week. bradley was put ashore in petersbay together with the two trappers who had been planning on using the petersbay trapping cabin jonsbu as their base for the season’s activities. during the 10 days they spent in petersbay, bradley claims to have assembled the radio transmitter, but not to have used it. oddly enough, one of the trappers there with him claimed that bradley did not, in fact, assemble it (simonsen 1941a). devold would also later claim that the radio equipment was not even unpacked from the suitcases (stordalmo 2006). bradley felt no direct hostility from the trappers, but they would not help him with his equipment and argued that he would not get a share of the season’s trapping income. the tiny group of men in the minuscule cabin (fig. 7) probably fig. 7 the norwegian trapping cabin of jonsbu, located in petersbay in eastern greenland, in 1939. bradley mentions having used the already existing antennas when he assembled the radio transmitter. (courtesy of the norwegian polar institute picture library.) 188 polar research 26 2007 181 – 194 © 2007 the author a cursed affair f. skarstein stoically accepted the cards that fate had dealt them and began preparations for the long, dark greenland winter ahead of them. the first us capture during wwii a memorandum for the president of the united states of america from rear admiral j. r. beardall, dated 18 september 1941, begins as follows (see fig. 8 for the full text): the substance of recent reports received from commander task group 6.5 (northeast greenland patrol, northland, north star, bear), is of possible interest to the president. the sixty ton norwegian steamer buskoe, chartered by norwegian expedition headed by hallvard devold, was boarded by u.s.c.g. cutter northland at myggbukta on 12 september. there was a crew of ten, with 11 passengers, all of whom were norwegians and one of whom was a woman. personnel carried the usual hunting guns and stated they left norway 29 august and arrived greenland on 4 september. information elicited indicated that three men and radio transmitter had been left at peter bay, two men at cape maurer and one at revet, with the remaining passengers to be landed at myggbukta, cape humbolt and havna. the buskoe was held pending further investigation and the northland proceeded to peter bay to remove radio station before ice closed in. the greenland government was informed at this time. apparently the norwegian government in london had no knowledge of this expedition. (file in franklin d. roosevelt library and museum) in his unpublished memoirs from his time onboard the uscgc north star as a lieutenant junior grade, retired captain david sinclair writes of the discovery and consequent capture of the buskø : one of the danes stationed at the ella island weather [station] was out working his trap line when he saw a trawler up a narrow fjord. he hurried back and reported to us. we immediately went up that fjord and found that the vessel had left. they had, in fact, steamed right into the hands of the cgc northland. it was a norwegian trawler named buscoe. there were 27 persons on board, most of them danish hunters and norwegian trappers, and one woman who said she was a nurse. also found were up to date radio transmitting equipment which may have been used for sending weather reports and information on allied shipping to german u-boats and axis-controlled territory. (sinclair, unpubl. memoirs) together, the northland (fig. 9), the bear (fig. 10) and the north star comprised the us navy’s northeast greenland fig. 8 the memorandum for the us president franklin roosevelt from rear admiral j.r. beardall, dated 18 september 1941, regarding the buskø incident. (courtesy of the franklin d. roosevelt presidential library and museum, new york.) fig. 9 the us coast guard cutter northland during her greenland patrol years. (courtesy of the us coast guard historian’s office.) f. skarstein a cursed affair polar research 26 2007 181 – 194 © 2007 the author 189 patrol, under the command of commander e. h. smith of the us coast guard. this patrol had been formed by direct orders of us president franklin roosevelt. during the summer of 1941, in a secret memorandum to the chief of naval operations, president roosevelt wrote, “i think the nazis will attempt to establish weather stations on the east coast of greenland, probably in the vicinity of scoresbysound. i suggest that you have the northland , the bear and one other iceworthy ship patrol the east coast of the island to prevent their setting up weather stations, bases or other military works” (quoted from memory by charles w. thomas as “wartime security prevented making a verbatim transcript” [thomas 1951]). onboard the northland , devold and the buskø ’s captain both admitted to the fact that they had dropped off three men with a radio station in petersbay a week earlier. whether or not they did this willingly would later become a topic of interest to the interrogation officers in boston. acting on this information, the northland moved up to petersbay. arriving at night, the northland launched a 10-man patrol under the command of lieutenant leroy mccluskey. bradley and the two trappers were discovered sound asleep, and brought onboard the northland . some sources would later claim that, under the pretext of making some tea for the visitors, bradley tried to burn a secret german codebook and instructions. selinger (2001) refutes this story as just that, storytelling. the only “codebook” bradley brought with him was a contemporary novel entitled det blåser fra dauingfjell ( a wind blows from ghost mountain ) (fig. 11), on which he would base his encoding of the weather reports. the americans proceeded to burn the radio equipment (fig. 12). the buskø in boston a prize crew was put onboard the buskø , while the norwegians were transferred to the northland and later to the bear for the journey to the american port of boston. with its inferior cruise speed, the buskø was tied to the uscgc bear and was literally pulled the 4800 km from the east coast of greenland to boston (as explained by crewmember peter sætre, who was on the expedition as an able seaman, to his friend helge ødegård). the arrival of the buskø on 14 october 1941 in boston created something of a media circus. the following day the story was in the headlines of many us newspapers, with varying degrees of sensationalism and accuracy (fig. 13). the new york times reported on the day of the arrival of the ships: “brings seized ship from greenland: [uscgc] bear [. . .] lands 21 prisoners, nazi operatives, at boston: woman and boy included” ( new york times 1941a). the “woman and boy” (not to be confused with the previously mentioned woman who gave birth during the overwintering) fig. 10 the us coast guard cutter bear . (courtesy of the us coast guard historian’s office.) fig. 11 the book on which bradley was supposed to base his coded weather reports to the germans. 190 polar research 26 2007 181 – 194 © 2007 the author a cursed affair f. skarstein were the wife of one of the trappers, not an unusual arrangement in those days, and a young apprentice onboard the ship. the next day the new york times ran another story on the buskø capture: “21 norwegians held in seized ship case: authorities at boston are silent on fate of crew aiding nazis” ( new york times 1941b). in time magazine of monday, 20 october 1941, the affair was mentioned under the title of “no trafalgar, no jutland” fig. 12 crew of the northland burning the german radio transmitter at jonsbu. (photographer unknown. courtesy of the peary-macmillan arctic museum, brunswick, usa.) fig. 13 page 3 of the new york times , 14 october 1941, featured photographs of (top) the patrol boat bringing the buskø crew into boston harbor and (bottom) the buskø herself being pulled while tied to the side of the us coast guard cutter (uscgc, not the uss, as stated in the newspaper’s caption) bear . (copyright © 1941 by the new york times co. reprinted with permission.) f. skarstein a cursed affair polar research 26 2007 181 – 194 © 2007 the author 191 (time magazine 1941b), contrasting this first involvement of the us in wwii with earlier more grand openings to large military conflicts. the following week, on monday, 27 october 1941, in a story shrewdly entitled “prisoners of defense”, time magazine once more touched on the buskø story, this time bringing attention to the peculiar legal status of the captives. as the us was not yet at war with germany (or norway for that matter), the status of the captives from the buskø and petersbay must have been a headache for the us bureaucracy, a fact that the sarcastic time magazine journalist did not fail to comment on: what was the status of the captives? were they prisoners of war or (since the u.s. is not in the war) prisoners of defence? under what law could they be held in jail? the unembarrassed justice department, which knows a lot about the law, smoothly ruled that the busko’s crew could be held “because they are not in possession of the proper traveling documents”. (time magazine 1941a) thus, bizarrely, the captives from what the us armed forces would later describe as their first capture during wwii (see, for example, thomas 1951) were being held for lacking proper immigration papers. the coast guard and the federal bureau of investigation interrogated all of the people onboard the buskø after capture and during the first few days in boston. the norwegian authorities in the usa then interrogated everyone again for three days starting on 21 october. the briefs from the sessions show that the work of the interrogation committee focussed on trying to clarify four main issues regarding each of the crew members. did they know about the german plans for bringing onboard a radio-equipped weather station before departure from laukvik? did they suspect that devold knew anything about this? were they or devold members of the norwegian nazi party? what would they want to do now that they had escaped from occupied norway? as it turned out, none of the expedition members (excluding bradley) appeared to be affiliated with the ns, and they had no previous knowledge of devold or of whether or not he was a member of the ns or was otherwise connected with the germans. the interrogation briefs show that all of the captives were now eager to participate in whatever way possible in liberating norway from the germans. as has been mentioned, john giæver was interned in the uk after being captured on the veslekari the previous summer. giæver later managed to become installed at the norwegian embassy in new york. he was sent to be present at the norwegian interrogations. with the exception of bradley, all the expedition members were released almost immediately after the norwegian interrogations ended. they had been judged to be “good norwegians” and, as expressed by the norwegian peter simonsen, a central figure in the interrogations, in a letter to the norwegian consulate in new york, there could not be any “uncertainty in releasing them. a few of them made a very good impression” (simonsen 1941b). bradley and devold were not among these. after stating that bradley had confessed to working on behalf of the germans to establish a weather station in greenland, simonsen concluded that his confession was “obviously enough for us to be sure that there is nothing that can be done on the norwegian side to get the man released” (simonsen 1941b). simonsen felt that the papers bradley had been carrying—copies of which he thought were being sent to london—might be of interest to norwegian intelligence because they mentioned names of norwegians involved in ns activities. as for devold, the main issue was that during the interrogations devold defended adolf hoel’s actions in norway, and was unable to give a satisfactory explanation of the expedition. without stating why, simonsen said he felt that it was unlikely that devold would not have known anything about the radio transmitter beforehand. in simonsen’s words: it could be possible, as devold explains, that the nsiu thought it so desirable to manifest norwegian interests in greenland that they scrambled together all the trappers one could muster and sent them off, and that the german arrangement with the radio station is as improvised as devold’s and bradley’s explanation gives the impression of. but totally convincing this explanation is not. (simonsen 1941b) neither bradley nor devold were released. conclusion it is difficult to make sense of the german wehrmacht’s behaviour in this incident. the whole arrangement appears very slapdash: contact with bradley was only made a couple of weeks before the departure of the buskø from norway, and his training consisted of a 5-day course in meteorology and radio operation, a rudimentary introduction at best. according to selinger (2001), it appears that the plan to establish a weather station in petersbay was unknown to the german navy. perhaps the whole german involvement in the buskø expedition was only a concealed prod to test the degree of american presence and intelligence in greenland. when approached by hoel and smedal during the planning stage of the expedition, representatives of the german government had expressed concerns about opening up a new front in open conflict with the americans (barr 2003). this explanation is somewhat supported by the germans explaining to bradley during the initial contact that they could have 192 polar research 26 2007 181 – 194 © 2007 the author a cursed affair f. skarstein used a trained german for this, but it was supposed to be a norwegian expedition and so a norwegian operator it had to be. if the weather station were discovered, it would be harder for the usa to link it directly to germany, or so krause and his superior zeibolt could have reasoned. however, judging by the media headlines in the wake of the buskø’s arrival in boston, the usa used this exposure of german activities on greenland for all it was worth in shaping opinion against germany. the story of the buskø was used in many different ways during the first few post-war years. from a us perspective, the mythology surrounding the us’s first naval capture during the second world war had an obvious propaganda purpose, and quickly grew out of proportion. a ridiculously embellished version was published in kurt singer’s spies and traitors of world war ii (1945). this account includes nazi agents trying to bribe their american guards (who patriotically retorted: “mac, du could us nicht briben, wir are americans”), and buskø crewmembers frantically lowering the “quisling flag, otherwise known as the swastika flag” upon entering boston harbor. upon entering the harbour, the buskø crew called out “we are not quislings, we are not nazis”, claimed singer (1945: 69), who also placed several germans onboard—“the few germans among the prisoners were quiet and despondent” (1945: 69–71)—although there were, in fact, none. more interesting is the version provided by the norwegian war pilot bernt balchen, who rose to (at least norwegian) fame in the us air force during the war (balchen et al. 1944). perhaps he felt it was a patriotic move to distance the buskø episode from norway. in any case, in his version of the story, the buskø is a “dubious looking danish ice-breaker” (balchen et al. 1944: 20). why not blame norway’s greenland arch-enemy denmark? in balchen’s narrative, the crew of the buskø were all danish. upon learning about the radio station, “a dozen heavily armed coast guard commandos . . . landed in a midnight blizzard, raided the shack, and captured some twenty nazi troopers in army uniforms who were asleep in their bunks” (balchen et al. 1944: 20). it would have been interesting to learn how 20 men had managed to fit themselves into the tiny cabin in petersbay. as news of the buskø’s fate started to reach hoel and the nsiu back in norway, the nsiu halted its expedition activity for the rest of the war. after the war the norwegians resumed some weather station activity in greenland, but in 1959 all norwegian activity ceased in eastern greenland. epilogue iacob rytter bradley was, according to bradley’s relatives in norway, put on trial in the usa, but was not convicted because of the nature of the evidence. he was given a 3month temporary visa to the usa, but for obvious reasons chose not to return to norway. he lived underground in the usa for two years until he was employed on a ship bound for paraguay, where he lived for a few years as a sailor. the family’s version of these events contrasts with the account given by stordalmo (2006), who holds that bradley was in captivity in the usa until 1947. according to the family, after his release from us custody, bradley found work in an argentine shipping company, and captained a vessel conducting petroleumrelated seismological investigations off the argentine coast. he later married and settled in sweden. he maintained contact with his norwegian family but, fearing treason charges against him, he did not set foot on norwegian soil again until the summer of 1979. the treason charges against bradley had by then exceeded the statute of limitations. he passed away in or around 1999, and was buried in sweden in accordance with jewish rites as this was his wife’s religion. it thus seems that his nationalism did not encompass the anti-semitism so characteristic of nazi ideology. hallvard devold was taken to the uk, interrogated for 30 days and was interned on the isle of man until the end of the war. in august 1945 he returned to norway, but was not tried for treason. as in the 1931 tiff with the danes over greenland (skarstein 2006), hallvard devold seems to have been a pawn in a game of strategy played by people more powerful and cynical than he. although devold had probably been made aware, through hoel, of the german curiosity in the details of the expedition, he might not have suspected the motives behind this interest. perhaps he reasoned that the germans were ensuring that the expedition was not just a cover for yet another boat escaping away from occupied norway. according to the briefs from the interrogations in boston, devold believed “there was not much anyone could do, as the contracts for the expedition were signed and there was no opportunity in the contracts for the crew to ask for leave” (simonsen 1941a). in a telegram to hoel on the day before the departure from laukvik, devold apparently reported that he felt “the whole thing had turned into a cursed affair” (simonsen 1941a). devold was never involved in polar activities again. the archives of the norwegian polar institute from the period after the war contain documents that suggest he may have considered a career in argentina, but this was never realized. he passed away in 1957. adolf hoel lost all his official positions at the nsiu, and his professorship at the university of oslo, immediately at the end of the war. after the incident, hoel claimed several times to have had no idea about the german plans to install a radio transmitter and telegraphist in greenf. skarstein a cursed affair polar research 26 2007 181 – 194 © 2007 the author 193 land until after the buskø’s departure. in hoel’s autobiography, published after his death, he referred to bradley as “a telegraphist whom the germans had slipped onboard without my knowledge” (hoel 1977: 64) another example is found in hoel’s correspondence, after the war, with the swedish geology professor hans ahlmann, who tipped off the norwegian authorities about hoel’s collaboration with the germans in the buskø affair. in 1949, hoel wrote a tense letter to ahlmann, who had been an old acquaintance, attempting to cast himself in a better light. the day before departure a representative of the german gestapo came to laukvik and forced onboard a radio station and a telegraphist that was to send meteorological messages to the german luftwaffe. i had no knowledge of this, and was notified of this only when the vessel was at sea. (simonsen 1941a) the prosecutors investigating the treason charges against hoel spent considerable time and effort exploring the degree to which he had collaborated with the germans during the preparations of the greenland expeditions in 1940 and 1941. obersturmführer hermann krause (who died shortly afterwards) and others were interrogated by the norwegian authorities after the war, but the prosecutors eventually dropped this serious charge from the case against hoel (stordalmo 2006). hoel was charged with other offences and was convicted for treason against norway. he was sentenced to 18 months of forced labour and lost his right to vote for 10 years. he wrote a scathing account of the unfair treatment he got during the trial, an account that was faithful to the details, as was hoel’s method in everything he did (hoel 1951). he died in 1964 of injuries from a traffic accident (barr 2003). according to a widespread belief in us naval history circles, the buskø never made it out to sea again, and the rotten remains can still be seen reaching up at the low tide at some forgotten pier in boston harbor (e.g., snow 1965: 255). this is not the case. on 15 january 1942 the buskø was released from us custody. the london-based norwegian exile government then made a war-related forced lease of the boat and rented her to the us war shipping administration from the end of april 1942 to the end of september 1944. the norwegian lease on the vessel ended on 30 september 1945. after a failed attempt that ended in engine repairs in st. johns, newfoundland, the buskø returned to norway, where she underwent serious restoration, including a new bow, cockpit and engine, in 1950 (fig. 14). then, in 1952, a terrible hurricane struck the sealing grounds in the ice belt outside of the east coast of greenland. the buskø went down with four other vessels in the drift ice, and a total of 79 men perished (ottesen 2001). acknowledgements i benefited from a great deal of information, advice and pointers from susan barr, erling bakken selnes, franz selinger, einar-arne drivenes and peter schmidt mikkelsen. leiv igor devold, eirik devold and members of the bradley family provided me with personal accounts of the main characters in the story. zar nik at the alaskan institute of dfc deserves firm credit for his internet research aid. helge ødegård, webjørn landmark and kristian eikrem helped with the details of the later fate of buskø and some of her crewmembers. ann kristin balto provided excellent help, as always, with navigating the amazing image archive of the norwegian polar institute. thanks to the us coast guard historian’s office and dr william h. thiesen for providing photographs of the coast guard vessels. references unless otherwise stated, all letters and telegrams referred to in this text are found either in the archives of the norwegian polar institute or in the private archives of adolf hoel. balchen b., ford c. & lafarge o. 1944. war below zero. london: george allen & unwin ltd. barr s. 2003. norway—a consistent polar nation? oslo: kolofon as. blom i. 1973. kampen om eirik raudes land. (the battle for eric the red’s land.) oslo: gyldendal. franklin d. roosevelt library and museum. safe file collection, box 4. accessed on the internet at http://www. fdrlibrary.marist.edu/fdrbx.html on 9 may 2007. fig. 14 the buskø in the drift ice off the east coast of greenland in the early 1950s. (reprinted from ottesen 2001 with the author’s permission.) http://www 194 polar research 26 2007 181 – 194 © 2007 the author a cursed affair f. skarstein hoel a. 1951. et oppgjør med landsmenn. (a confrontation with countrymen.) oslo: minerva forlag. hoel a. 1977. mitt liv i og for polartraktene. (my life in and for the polar regions.) oslo: john griegs forlag. new york times 1941a. brings seized ship from greenland. 14 october, p. 6. new york times 1941b. 21 norwegians held in seized ship case. 16 october, p. 3. norwegian state archives. documents in the folder expeditions 1941, box no. 181 in the archive s-0902 norsk polarinstitutt, norwegian state archives, tromsø, norway. odsbjerg a. 1990. nordøstgrønlands slædepatrulje 1941–1945. (north-eastern greenland’s sledge patrol 1941–1945.) copenhagen: komma publisher. ottesen j. 2001. ishavsskuter iii. (arctic ocean vessels iii.) ullsteinvik: fotoarkivet. pryser t. 2001. hitlers hemmelige agenter: tysk etteretning i norge 1939–1945. (hitlers secret agents: german intelligence in norway 1939–1945.) oslo, universitetsforlaget. selinger f. 2001. von “nanok” bis “eismitte”: meteorologische unternehmungen in der arktis 1940–1945. (from “nanok” to “ice centre”: meteorological enterprises in the arctic 1940–1945.) berlin: schriften des deutschen schiffahrtsmuseums. simonsen p. 1941a. interrogation briefs from the norwegian consulate in boston, from the private archives of peter simonsen in the folder pa1298 peter simonsen, s/s buskø report, national archival services of norway, oslo. simonsen p. 1941b. letter from peter simonsen to the general consul rolf a. christiansen, from the private archives of peter simonsen, in the folder pa1298 peter simonsen, s/s buskø report, national archival services of norway, oslo. sinclair d. unpublished memoirs of captain david sinclair. accessed on the internet at http://www.uscg.mil/history/ weboralhistory/capt_david_sinclair_17.html on 9 may 2007. singer k. 1945. spies and traitors of world war ii. new york: prentice hall. skarstein f. 2006. erik the red’s land: the land that never was. polar research 25, 173–179. snow e.r. 1965. the fury of the seas. new york: dodd, mead and company. sørensen l.n. 1958. henry rudi: isbjørnkongen. (henry rudi: king of the polar bears.) oslo: gyldendal. stordalmo k.e. 2006. grønnlandssakens utvikling under den andre verdenskrig. (the greenland case and its development during the second world war.) tromsø: university of tromsø. thomas c.w. 1951. ice is where you find it. new york: the bobbs-merrill company, inc. time magazine 1941a. prisoners of defense. accessed on the internet at http://www.time.com/time/magazine/article/ 0,9171,849519,00.html on 24 april 2007. time magazine 1941b. no trafalgar, no jutland. accessed on the internet at http://www.time.com/time/ magazine/article/0,9171,851301,00.html on 12 june 2007. http://www.uscg.mil/history/ http://www.time.com/time/magazine/article/ http://www.time.com/time/ doi:10.3402/polar.v33.21821 r e s e a r c h / r e v i e w a r t i c l e impact of summertime anthropogenic emissions on atmospheric black carbon at ny-ålesund in the arctic jianqiong zhan & yuan gao department of earth & environmental sciences, rutgers university, 101 warren street, newark nj 07102, usa keywords equivalent black carbon; ny-ålesund; human influences; transport efficiency. correspondence yuan gao, department of earth & environmental sciences, rutgers university, 101 warren street, newark, nj 07102, usa. email: yuangaoh@andromeda.rutgers.edu abstract measurements of equivalent black carbon (ebc), calculated from aethalometer measurements of light attenuation, were carried out in july 2011 at ny-ålesund in the arctic. highly elevated ebc concentrations were observed within the settlement of ny-ålesund, with a median value of 17 ng m �3 , which was about two times the background level. results from the ensemble empirical mode decomposition method suggested that about 60�80% of atmospheric ebc concentrations at ny-ålesund were from local emissions, while only 20�40% arrived via atmospheric transport. the estimated average local emission rate was 8.1 g h �1 , with an uncertainty of approximately a factor of two. the pollution plume was confined to 10 km downwind of the settlement, with the total ebc deposition estimated to be 6.4�44 ng m�2 h�1. this may affect snow black carbon (bc) concentrations in nearby glaciated areas. the efficiencies of the long-range transport were estimated based on cluster analysis and potential precipitation contribution function, and the results implied that transport from western europe is more efficient than from central russia, on account of relatively rapid transport from western europe and infrequent precipitation along this route. however, there was no correlation between air mass back-trajectories and ebc concentrations, suggesting that the contribution of long-range transport to ebc measured in ny-ålesund might be not significant in this season. black carbon (bc) in the atmosphere affects the radiative balance of the arctic due to its strong light absorption (shindell & faluvegi 2009). although organic carbon has an overall cooling effect on the atmosphere (solomon et al. 2007), for the highly reflective snow/ice surface of the arctic, the mixtures of organic carbon and bc still exert positive top-of-atmosphere radiative forcing (flanner et al. 2009). the impact of bc can continue even after it is removed from the atmosphere and deposited on ice or snow, through the reduction of surface albedo (doherty et al. 2010; hadley & kirchstetter 2012). over the 20th century, about 20% of the warming and snow/ice-cover melting in the arctic is due to the bc-albedo effect (koch et al. 2011). these findings identify bc as a critical climate forcing agent in the arctic. several groundand aircraft-based investigations of atmospheric bc have been carried out in the arctic. annual mean concentrations of bc ranged from 26 to 49 ng m �3 , with values at alert and zeppelin station higher than those at barrow and summit (hirdman, sodemann et al. 2010). a pronounced seasonal cycle has been found, with a maximum in winter/early spring (i.e., the haze season) and a minimum in summer (sharma et al. 2006; eleftheriadis et al. 2009). strong seasonal variations are consistent with atmospheric transport patterns in the arctic (stohl 2006; hirdman, burkhart et al. 2010). vertical concentration profiles of bc were observed during the arctic research of the composition of the troposphere from aircraft and satellites mission in 2008. in the spring, two peaks were revealed in the profile of bc mass mixing polar research 2014. # 2014 j. zhan & y. gao. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 ratio: one was at 5.5 km, with a mass mixing ratio of 150 ng kg �1 in the aged air mass; the other one, at 4.5 km, had a mass mixing ratio of 250 ng kg �1 and was associated with biomass burning (spackman et al. 2010). the vertical stratification of bc increased with altitude at lower altitudes (650 hpa), whereas at higher altitudes it decreased toward the middle troposphere (jacob et al. 2010; spackman et al. 2010). the summertime bc concentrations varied between 5 and 100 ng kg �1 from 0 to 12 km in altitude, with higher bc concentrations in the lower troposphere in july. as there were widespread fires during the aircraft campaigns, the enhancement of bc could have resulted from increased biomass burning (spackman et al. 2010), which might not be representative of typical bc distributions in summer. northern eurasia has repeatedly been shown to be the major source for the bc concentrations observed at the arctic surface stations in winter and spring (stohl 2006; hirdman, burkhart et al. 2010). in summer, transport from the surrounding continental locations is limited by the weaker and more northern extent of the polar dome (klonecki et al. 2003; law & stohl 2007) as well as more frequent precipitation (barrie 1996; bourgeois & bey 2011). as result of low efficiency of longrange transport, local aerosol sources become much more important in summer. recent studies have highlighted the role of local emissions within the arctic. measurements made at barrow, alert and zeppelin station over more than a decade have indicated that bc concentrations measured in the arctic are highly sensitive to emissions within the arctic (hirdman, sodemann et al. 2010). in the last 10 years, human activities such as general transport (aviation and shipping), oil and gas flaring and resource exploitation have increased; these could lead to strongly elevated concentrations of bc in the arctic (granier et al. 2006; dalsøren et al. 2007; lack et al. 2008; vestreng et al. 2009; corbett et al. 2010; lee et al. 2010; deangelo 2011; quinn et al. 2011). around 4.5 gg yr �1 of bc is contributed from arctic shipping, and this may increase global climate forcing by at least 17% compared to warming due to co2 emissions from these vessels (ca. 42 000 gg yr �1 ; corbett et al. 2010). lee et al. (2010) also highlighted aviation emissions associated with major routes in the vicinity of 608n. johnson et al. (2011) suggested the mean soot emission rate is 2.0 g s �1 at a calculated uncertainty of 33%, from measurement of the emission rate from oil and gas flaring in uzbekistan. however, these emissions are still not well characterized and specific emission factors are still uncertain due to the lack of measurements at many locations. in svalbard, local human activities, such as motor vehicle use, electric power production and domestic combustion, persistently occur, contributing to the loading of bc in the air, but more quantitative evaluations of these contributions are needed. to characterize the anthropogenic emissions affecting the bc concentration in svalbard, field measurements were carried out within and near the settlement of nyålesund in july 2011, the peak season of local human activities. in this paper, we present the measurement results and estimate the contribution of local emissions, the emission rates and the bc deposition rates using model simulations. these results will be useful for interpreting other data sets in the region, for planning future measurement campaigns in this region and for developing emission reduction strategies in the arctic. methods measurement sites the measurements were made in ny-ålesund, on the island of spitsbergen in the svalbard archipelago. the sampling sites were one site at the chinese yellow river station (yrs) (78.928n, 11.938e, 13 m a.s.l) within the ny-ålesund settlement and three sites around ny-ålesund: s2 (78.908n, 12.078e, 126 m a.s.l), s3 (78.998n,12.068e, 134 m a.s.l) and s4 (78.968n 11.608e, 33 m a.s.l; fig. 1). data measured at zeppelin station (78.908n, 11.888e, 474 m a.s.l) by eleftheriadis et al. (2009) were used in this study for comparison. zeppelin station is situated on the mountain of zeppelinfjellet, 1 km south of, and over 400 m above, the settlement, where contaminants from ny-ålesund are minimal (hirdman, sodemann et al. 2010). the yrs is situated in ny-ålesund, directly below zeppelin station; it was therefore directly affected by local emissions from tourism and research-related activities in the settlement. s2 was located 4 km south-east of ny-ålesund, on the glacier midtre lovénbreen. s3 lay on the island of blomstrandhalvøya, on the other side of the fjord from ny-ålesund and at a distance of about 5 km from the settlement. s4 was situated on the coastal plain of kvadehuksletta at the north-west point of the peninsula brøggerhalvøya, about 10 km away from ny-ålesund. bc measurement and meteorological data collection aethalometers have been widely used for measuring bc concentrations in the arctic (sharma et al. 2006; eleftheriadis et al. 2009; hirdman, burkhart et al. 2010). the device measures the attenuation of light transmitted through particles that accumulate on a quartz fibre filter and interprets the rate of increase of optical attenuation summertime anthropogenic emissions and atmospheric black carbon j. zhan & y. gao 2 (page number not for citation purpose) citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 in terms of the concentration of optically absorbing material in the sample air stream. since these optically based measurements rely on some assumptions to convert particle light absorption to bc concentrations, the data derived from this method are also called equivalent bc (ebc; sharma et al. 2004). in this study, an ae42 model aethalometer (7-wavelength; only l ca. 880 nm reported here; magee scientific, berkeley, ca, usa) was used at the yrs site, while model ae51 instruments (magee scientific) were used at sites s2, s3 and s4. temporal resolutions were 10 min for the ae42 unit and 5 min for the ae51 units during the measuring period of 5�19 july 2011. the specific mass absorption coefficient aap �15.9 m 2 g �1 was used to calculate bc mass concentrations from the ae42 device. this value was derived from simultaneous measurements of light absorption and thermo-optical elemental carbon mass concentration by nyeki et al. (2005), which was also applied in ebc calculations at zeppelin station by eleftheriadis et al. (2009). data from the ae51 units were corrected by comparing ae42 and ae51 measurements at the same place. the scattering correction wasn’t employed in this study since aerosols in these remote areas were well-aged, requiring little or no correction (hansen et al. 2007).the overall uncertainty on the aggregated data is on the order of 10% (hansen et al. 2007). to circumvent the potential error induced through the use of two different instruments, co-location experiments were carried out both before and after experiments. measurement data are summarized in table 1. meteorological parameters, for example, air temperature, wind speed, wind and relative humidity, were collected simultaneously with a temporal resolution of one hour. precipitation data were from ny-ålesund station, which is around 0.2 km away from yrs. the arithmetic mean, maximum and minimum for each parameter are presented in table 2. atmospheric transport and dispersion model the hybrid single-particle lagrangian integrated trajectory 4 (hysplit_4) model, created by the us national ocean and atmospheric administration (draxler & hess 1998), was used to generate both forward and backward trajectories and complex dispersion/deposition simulations, using us national centers for environmental prediction/national center for atmospheric research (ncar/ncep) reanalysis data. the data were provided at a horizontal resolution of 2.58�2.58, 17 vertical levels up to 10 hpa, and a temporal resolution of six hours. emission rates were estimated by fitting the predications from dispersion model to the observed concentration difference between within and outside the community, and then the subsequent advection, dispersion and deposition of ebc were simulated, using ncar/ncep reanalysis meteorological data fed into the hysplit model. wet deposition was calculated using precipitation data from the european centre for medium-range weather forecasts (ecmwf). the washout ratio was calculated from the scott washout ratio (scott 1978). fig. 1 map of the peninsula brøggerhalvøya, showing the locations of ny-ålesund and the sampling sites: chinese yellow river station (yrs, 11.938e, 78.928n, 13 m a.s.l), s2 (12.078e, 78.908n, 126 m a.s.l), s3 (12.068e, 78.998n, 134 m a.s.l), s4 (11.608e, 78.968n, 33 m a.s.l). table 1 comparison of equivalent black carbon (ebc) concentrations in svalbard, alert (nunavut) and barrow (alaska). station location ebc concentration (ng m �3 ) a time period references yellow river station 11.938e, 78.928n, 13 m a.s.l 17 (4.1�38) july 2011 this work s2 12.078e, 78.908n, 126 m a.s.l 5.3 (1.0�7.8) july 2011 this work s3 12.068e, 78.998n, 134 m a.s.l 6.6 (0.0�15) july 2011 this work s4 11.608e, 78.968n, 33 m a.s.l 4.7 (0.0�12) july 2011 this work zeppelin station 11.928e, 78.938n, 474 m a.s.l 7 (3�11) summers 1998�2007 eleftheriadis et al. 2009 11 summers 1990�1992 heintzenberg & leck 1994 gruvebadet 11.928e, 78.938n, 10 m a.s.l 5 summers 1979�1990 heintzenberg & leck 1994 alert 62.38w, 82.58n, 210 m a.s.l 12�26 summers 1989�2003 sharma et al. 2004, 2006 barrow 156.68w, 71.38n, 11 m a.s.l 9�24 summers 1989�2003 sharma et al. 2006 a mean (minimum�maximum). j. zhan & y. gao summertime anthropogenic emissions and atmospheric black carbon citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 time-frequency analysis to better understand the properties and physical mechanism hidden in the ebc data, ensemble empirical mode decomposition (eemd) was used to isolate and extract various temporal scales in data. these various temporal scales were further linked to different sources. there are other popular tools, such as fourier analysis, wavelet analysis and wigner-ville distribution, which can also decompose the data into the components of different timescales, but they are limited to either linear or stationary processes, and require a priori function basis. this often makes their applications to data from nonlinear and non-stationary processes problematic. eemd is an adaptive method that is designed specifically for analysing nonlinear and non-stationary data without imposing irrelevant mathematical rules (wu & huang 2009). this approach consists of sifting an ensemble of white noise-added signal, and obtains the mean of corresponding intrinsic mode functions (imfs) that bear the full physical meaning and a time-frequency distribution, and also gets the corresponding average residual which is identical to the trend. further details on the eemd method can be found in wu & huang (2009). the results are tested by statistical significance at the 95% confidence level based on a testing method suggested by wu & huang (2004) against the white noise null hypothesis. results and discussion ebc concentrations the concentrations of ebc (fig. 2) at yrs ranged from 4.1 to 38 ng m �3 , with a median value of 17 ng m �3 , which was higher than values observed outside the nyålesund settlement at s2, s3 and s4, where median ebc concentrations were 5.3, 6.6 and 4.4 ng m �3 , respectively. the median value found at yrs was in the range of the summer monthly average at alert (12�26 ng m�3) and barrow (9�24 ng m�3) from 1989 to 2003 (sharma et al. 2006), but higher than ebc concentrations at zeppelin station (3�11 ng m�3; eleftheriadis et al. 2009). the levels of ebc at s2, s3 and s4 were comparable to measurements taken at zeppelin station (475 m a.s.l) with a median ebc concentration of 7 ng m �3 (eleftheriadis et al. 2009). these levels were also similar to aircraft measurements over the arctic in july 2008, where the bc mass concentration was ca. 10 ng kg �1 above 3 km and ca. 5 ng kg �1 below 3 km (liu et al. 2011) as well as the gruvebadet sea-level site near yrs (78.928n, 11.898e) measured by heintzenberg & leck (1994), who reported 5 ng m �3 for summer/autumn from 1979 to 1990. the results showed that the ebc concentration at yrs was higher than the levels of ebc at zeppelin station and ground-based stations around the settlement. similar results were reported by hermansen et al. (2011): so2 and soot levels were higher in the ny-ålesund settlement than at zeppelin station. the aerosol scattering coefficient was also ca. 13�66% lower at zeppelin, suggesting relative cleanliness at zeppelin station due to its elevation at 474 m a.s.l, above a temperature inversion layer, which limited vertical mixing (di liberto et al. 2012). residential emissions were presumably a factor contributing to the elevated ebc concentration at yrs. this observation is further illustrated in fig. 3. as shown, ebc concentrations corresponded to wind directions; higher ebc concentrations were associated with being downwind*especially south*of ny-ålesund. variations and average ebc concentration during the daytime were larger than those at night, indicating more complicated and stronger sources in the daytime than at night. this confirms that local human activities were one of the major sources affecting the concentration of ebc at ny-ålesund. local meteorological influences the relationships between meteorological parameters and ebc concentrations were tested for statistical significance. pearson’s correlation coefficient and principal component regression (pcr) were used to estimate the influence of meteorological parameters on the ebc concentrations. pcr assumes that the variables have normal distributions. however, some of our measured data are not normally distributed; therefore logarithmic table 2 correlations between equivalent black carbon (ebc) concentration and meteorological parameters at yellow river station, ny-ålesund. asterisks indicate correlation significant to the 99% confidence level (two-tailed). mean and range correlation coefficient p temperature (8c) 6.5 (2.4�10.5) 0.22* 0.000 pressure (hpa) 1011.0 (997.2�1023.1) �0.21* 0.000 wind speed (m s �1 ) 3.2 (0.0�12.5) �0.10* 0.000 total precipitation (mm/day) 0.8 (0.0�11.1) �0.10* 0.000 relative humidity (%) 80 (57�93) 0.03 0.125 summertime anthropogenic emissions and atmospheric black carbon j. zhan & y. gao 4 (page number not for citation purpose) citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 transformations were done for the ebc concentrations, wind speed and relative humidity to avoid violation of the normality assumption. the levels of ebc were significantly (pb0.000) related to temperature, wind speed, atmospheric pressure and total precipitation (table 2). among the meteorological parameters, temperature had the greatest effect on the ebc concentration, with a pearson’s correlation coefficient of 0.22 (pb0.000), indicating higher levels of ebc during higher temperature periods. a negative correlation was found between temperature and boundary layer height, with a pearson correlation of �0.38 (pb0.000). this suggests that high ebc concentrations in warm air might relate to shallow boundary layer, which was created by temperature inversion (tjernström 2005). observations and ncar/ncep) reanalysis data reveal that elevated temperature inversion dominates 91% of summer months (tjernström & graversen 2009), and this was more pronounced in a warmer summer (e.g., 2007) compared to other years (2003�06 and 2008; devasthale et al. 2010). temperature inversion creates a stable and shallow mixing layer, which limits the vertical transfer of ebc between the surface and the free troposphere, trapping ebc close to the ground. this suggests that temperature may indirectly influence ebc concentration when a shallow boundary layer is capped by temperature inversion in the summer. as expected, a negative correlation was found between ebc concentration and total precipitation due to removal via wet deposition. a negative relationship was found between the ebc concentration and wind speed, with a pearson correlation of �0.10 (pb0.000), indicating the dilution effect of winds on the ebc concentrations. relative humidity showed less significant correlation with the ebc concentrations, with a pearson correlation fig. 2 time series of equivalent black carbon (ebc) concentrations, air mass transport pathways (dashed line; ao represents the arctic ocean sector, eu stands for western europe and cr stands for central russia) and meteorological parameters (total precipitation, relative humidity, wind speed, wind direction, air temperature, pressure). fig. 3 variations in equivalent black carbon concentration (ng m�3) affected by wind directions at yellow river station. individual wind direction measurements are accumulated and the relative frequency is shown as a percentage. j. zhan & y. gao summertime anthropogenic emissions and atmospheric black carbon citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 of 0.033 (p �0.34), suggesting that humidity did not directly affect ebc concentrations since most of the bc particles were hydrophobic. the association between selected meteorological parameters (temperature, wind speed, relative humidity, atmospheric pressure and total precipitation) and ebc concentration was analysed by pcr. the selected meteorological parameters can only explain 19% of the variation in ebc concentrations (pb0.000), suggesting that other factors are influencing ebc levels in the area, such as the distance to sources and the strength of sources and sinks. ebc concentration from local emissions and long-range transport ny-ålesund can be both a source and receptor for pollutants because some are locally generated and some are transported there over long distances. to evaluate these two factors, local emissions were assumed to be generated by both intermittent, short-term activities and continuous activities, while long-range transport, which is controlled by atmospheric circulation, occurs at various temporal scales (stohl 2006). in order to separate various signals hiding in the data, eemd was used to decompose the ebc data into various frequency signals. the results included imfs, which represent some specific scale of oscillation, and a residual that is identical to the trend, expressed as: ebctotal¼ imf1þimf2þ . . .þ imfnþtrend (1) bc at ny-ålesund can come from local emissions (ebclo) and long-range transport (ebctr). ebctotal¼ ebcloþebctr (2) here, we assume that local emissions were generated by both random and continuous activities, which can be represented by high-frequency (imf1, imf2. . . imfm) and extremely low signals (elow-lo), which were included in trend. hence, ebclo was defined as follows: ebclo¼ imf1þimf2þ . . .þimfmþelow�lo (3) long-range transport is controlled by atmospheric circulation at various temporal scales (stohl 2006); therefore, it can be expressed with specific frequency imfs and as part of the signal in trend. so ebctr were expressed as: ebc tr ¼ imfmþ1þimfmþ2 þ imfmþ3þ . . .þimfnþelow�tr; (4) where imfm�1,imfm�2,imfm�3,. . .imfn are relatively low-frequency signals in imfs and elow-tr was the result from longer time scales of atmospheric circulation. based on these assumptions and principles of eemd, the residual is understood to represent longer-term oscillation, which is associated with continuous local emissions and longer timescales of transport. that is: trend ¼elow�loþelow�tr (5) in this study, ebc data were decomposed into 10 imfs, corresponding to periods ranging from two hours to more than five days. generally, the frequencies of local human activities are higher than those of long-range transport and they are characterized by diurnal variation or shorter periods of variations. eleftheriadis et al. (2009) pointed out that diurnal variation in ebc concentration was less than 91 standard deviation range at zeppelin station during the summer months (jja), suggesting that the diurnal variation was negligible; therefore, one day was chosen as a cut-off point and frequencies of one day or less were identified as being associated with local emissions, while variances lasting more than one day were ascribed to long-range transport. when eqns. 1�5 were applied to the data measured at yrs, s2, s3 and s4, the results indicated that 60�80% of ebc at the yrs was from local emissions. the processes controlling bc in the atmospheric boundary layer include emissions, atmospheric transport and deposition or eventual ventilation (wang et al. 2011). these are considered below. local emissions ebc emission rates. the atmospheric dispersion factor (d, h m �3 ) from the source to the receptor was calculated using the hysplit model, and then the emission rates (q, ng h �1 ) were obtained by dividing the ebc concentrations (m, ng m �3 ) from local emissions by the relevant dispersion factors, according to the equation: q �m/d. ebc concentrations (m, ng m�3) from local emissions were calculated using eqn. 3. here, a six-hour time average of the dispersion factor was set as the model output, and the average emission rate was calculated. a median value of 8.1 g h �1 was estimated, with a range from 1.0 to 25 g h �1 . the uncertainty in these factors was approximately a factor of two due to the uncertainty associated with measurements and accuracy of the dispersion model and meteorological data. according to the average pm 2.5 emission rates measured during on-road testing in south east queensland, australia, the emission factor was 15 g h �1 for diesel buses or 1.7 g h �1 for lightduty vehicles driving at an average speed of 50 km h �1 (keogh et al. 2010). the emission rate at ny-ålesund was equivalent to about half the emission produced by a bus, or to emissions from about five light-duty vehicles constantly driving. although emissions from local summertime anthropogenic emissions and atmospheric black carbon j. zhan & y. gao 6 (page number not for citation purpose) citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 human activities were miniscule compared to the emissions released from the mainland, these emissions in the vulnerable arctic may change the physical and chemical properties of bc particles and more efficiently deposit to snow/ice surfaces (deangelo 2011). ebc concentration distribution estimate. using the hysplit model, the spatial pattern of near-ground level ebc concentration due to local emissions was modelled every six hours and then averaged over the measurement period of this study. a contour plot of the average ebc concentration around ny-ålesund is shown in fig. 4a. hourly wind speed and direction at 2-m height during the measurement period is shown by the wind rose diagram (also in fig. 4b). the prevailing winds during the experiments were typically either from the east�south-east or north�north-west. the concentration contour maps demonstrated that the trajectories of the ebc plumes released from ny-ålesund correlated well with the wind direction, and the plume shifted as wind changed in direction. the highest ebc concentration was about 14 ng m �3 at ny-ålesund, decreasing markedly with distance from the settlement as ebc was dispersed in the atmosphere. the concentrations of ebc reduced to 4.0 ng m �3 (30%) within 2 km of the source, with the majority of the downwind area having concentrations of less than 2.0 ng m �3 . however, the impact of these emissions was irregular, such that puffs were more likely to cover the southern sectors (south�south-east, south, and south�south-west), where the snowor ice-covered surface was more sensitive to pollution compared to other exposed land, rather than the west�north-west sector. ebc dry deposition estimate. in this study, dry deposition of ebc was estimated by the product of dry deposition velocities (vd) and atmospheric ebc concentrations. generally, vd was calculated by surface resistance, which was a function of aerodynamic resistance, friction velocity and surface type (vignati et al. 2010). here, a deposition velocity of 0.030 cm s �1 was chosen based on results presented by nilsson & rannik (2001) and held et al. (2011) of eddy-covariance flux measurements in the arctic, which was input to the model to determine the ebc dry deposition flux from local emissions around ny-ålesund. each six-hour dry deposition flux was calculated; a contour map for the average of the whole period is shown in fig. 5a. the deposition distribution pattern was similar to the concentration distributions, with the highest deposition of ebc directly downwind of the source, which was then immediately reduced to 4.0 ng m �2 h �1 (30% of the central value) within 2 km of the source. major depositions occurred in glaciated areas in the south�south-west and south�south-east sector. ebc dry deposition from local emissions in summer ranged from 0.0 to 18 ng m �2 h �1 and total dry deposition (local emissions�long range transport) ranged from 4.3 to 32 ng m �2 h �1 (100�770 ng m�2 d�1) within 10 km (table 3). this is in the lower range of dry deposition flux over snow/ice (about 100�5300 ng m�2 day�1) based on the observed bc depletion in the boundary layer in spring, including the period of biomass-burning that was documented (spackman et al. 2010). ebc wet deposition estimate. wet deposition was also considered as a process controlling atmospheric bc concentration and affecting bc concentration in the fig. 4 (a) contour plot of the average equivalent black carbon (ebc) concentrations during the entire experiment period at yellow river station (yrs) attributed to local emissions. (b) the wind rose plot was made for the entire experiment period at yrs. individual wind direction measurements were accumulated and the relative frequency is shown as a percentage. wind speed (m s �1 ) is expressed by different colours. j. zhan & y. gao summertime anthropogenic emissions and atmospheric black carbon citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 snow surface since the observation site was subjected to periods of heavy precipitation during summer, and a substantial fraction of aerosol might be washed out and deposited on the snow/ice surface (liu et al. 2011). here, wet deposition flux was calculated as follows: fw ¼c�p¼ 10 �3 �ebcair�wr�p; (6) where ebcair is the ebc concentration in the air (ng m �3 ), wr is the washout ratio, p is precipitation rate (mm h �1 ) and fw is the wet deposition flux (ng m �2 h �1 ). the washout ratio, wr ¼ bcsnow or rain=bcair; can be calculated by comparing of the amount of snow or rain with the concentration of bc in the air. hegg et al. (2011) compared the washout ratio from fieldwork and the scott washout ratio model (scott 1978), and found that the washout ratio predicted by the model was in reasonable agreement with the observed value. hence, the scott washout ratio was used in this study as follows: wrðbcþ¼ 14000 � msð0þ bcair�p 0:88 þ 1000 � fbc �ð1 � 0:0441 � p�0:88þ 1:56 þ 0:44 � in p ; (7) where wr(bc) was the bc washout ratio, ms(0) was the concentration of bc (ng m �3 ) in hydrometeors at the top of the riming zone, fbc was scavenging efficiency, bcair was the air concentration of bc, and p is the precipitation rate in mm h �1 . here, we set ms(0) �0.1 bcair (scott’s warm rain value) and fbc �0.5, since hegg et al. (2011) reported that a predicted washout ratio using these two parameters agreed reasonably with the observed value for warm rain. the total precipitation was from the ecmwf database. the wet deposition due to fig. 5 (a) contour plot of dry deposition averaged over the entire experiment period and (b) wet deposition from local emissions. table 3 atmospheric deposition fluxes of equivalent black carbon in ny-ålesund, svalbard, and fairbanks, alaska. estimated atmospheric black carbon flux (ng m�2 h�1) station location time period sources dry deposition flux wet deposition flux total deposition flux wet deposition (%) references ny-ålesund, svalbard 11.60�12.068e, 78.92�78.998n 13�134 m a.s.l july 2011 local emissions 1.8�18 0.10�9.6 1.8�27 10�70 this work total (local emissions�long-range transport) 4.3�32 2.1�12 6.4�44 22�44 fairbanks, alaska 135�1658w, 65�758n, 0.1�7.4 km a.s.l april 2008 total 4.2�220 � � 91 spackman et al. 2010 summertime anthropogenic emissions and atmospheric black carbon j. zhan & y. gao 8 (page number not for citation purpose) citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 local emissions was calculated every six hours; the average was calculated for the whole period as shown in the contour map (fig. 5b). wet deposition from emissions ranged from 0.10 to 9.6 ng m �2 h �1 ; total wet deposition ranged from 2.1 to 12 ng m �2 h �1 within 10 km (table 3). wet deposition accounted for 22�44% of total ebc deposition, which was lower than 78917% inferred from the aerocom multimodel assessment (textor et al. 2006) as well as the results from spackman et al. (2010), who reported that wet deposition accounted for 91% of total bc deposition to the arctic in spring and 85% in winter. the total ebc depositions, which were defined as the sum of dry and wet deposition, were about 6.4�44 ng m �2 h �1 . local emissions of bc contribute ca.15% to the total deposition within a radius of 10 km at nyålesund. this was similar to the figure reported for svalbard by norway’s climate and pollution agency: 20% of total deposition came from local emissions (vestreng et al. 2009). this analysis demonstrates that the environmental impacts of deposition from an individual source can be localized, with dispersion of pollutants in the atmosphere resulting in negligible environmental burdens beyond about 10 km downwind. even though the pollution puffs from local emissions were more likely to pass over the glaciated areas in the southern sectors, the total deposition flux of ebc from local emission over these areas was less than 10 ng m �2 h �1 . if we assume that all of this bc is deposited on the top 1 cm of snow and the density of snow is 0.40 g cm �3 , then local emissions only contribute 1.8 ng bc per gram of snow each month. however, it is comparable to the average bc concentration average (about 5 ng g �1 ) in fresh snow previously measured in the same region in late may (hegg et al. 2011). however, this analysis only considers a single emission source. a variety of uncertainties should be included in these calculations because the physical and chemical characteristics of bc are not constant. rather, they involve different source and emission conditions, as well as the size, mixing state and chemical composition of bc particles. hence, a far more sophisticated model should be used or developed to evaluate bc dispersion and deposition. long-range transport cluster analysis. backward trajectories can provide information about the transport patterns and potential sources of the observed aerosols (draxler & hess 1998; stohl 2006). the 10-day backward trajectories were calculated every six hours using hysplit_4 and meteorological data to investigate the effect of long-range transport. here, the arrival elevation of 540 m a.s.l was chosen for each trajectory calculation, which was the most representative arriving height (worthy et al. 1994; huang et al. 2010). cluster analysis was used to classify the trajectories into different groups. the results of trajectories and cluster analysis (fig. 6a) showed that ny-ålesund was impacted by three different atmospheric transport regimes during the study period. about 41% of air mass came from the arctic ocean, 31% originated from western europe and 28% came from central russia. most of the air mass was confined to the north of 658n, except the air mass from central russia, which could originate from 608 n. this air mass could pass over settlement areas. the contribution of emissions from fig. 6 (a) ten-day back trajectories were coloured by air pressure and major transport pathways calculated by cluster analysis, labelled by identification of each cluster and frequency of occurrence. both were generated by the hysplit model. ao represents the arctic ocean sector, eu stands for western europe and cr stands for central russia. (b) map of potential precipitation contribution function probability. j. zhan & y. gao summertime anthropogenic emissions and atmospheric black carbon citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 these areas to arctic bc not only depends on sources but also the processes that occur en route, such as precipitation. therefore the potential precipitation along each route and the temporal variance of each pattern were combined to interpret the contribution from each sector. potential precipitation contribution. removal during transport is also an important factor affecting the efficiency of pollution transportation. the analysis of the potential precipitation contribution function (ppcf) was used to link atmospheric transport regimes with precipitation, given the possibility that rainfall occurred during the passage of the plume. the ppcf values for the grid cells ppcfij were the conditional probabilities that an air parcel passing through the ij-th grid cell was accompanied with precipitation and was defined as: ppcfij ¼ miij=n niij=n ¼ p½bij� p½aij� ; (8) where nij was the total number of end points that fall in the ij-th cell, and mij was the number of end points in the same cell that were associated with precipitation. p(bij) was the probability of precipitation in the ij-th cell, and p(aij) was the probability of trajectories that pass over the ij-th cell. to reduce the effect of small values of nij, an arbitrary weight function w(nij) was applied to downweight the ppcfij values. here, the weight function w(nij), given by hopke et al. (1995), was defined as: wðnijþ 1:0 if nij � 4 0:75 if nij ¼ 3 0:50 if nij ¼ 2 0:25 if nij ¼ 1 8 >>< >>: (9) combining the heights of transport pathway and ppcf distribution shown in fig. 6, indicated that air masses from western europe experience less precipitation than air masses passing over central russia. western europe was therefore a probable source for the bc ending up in svalbard, since pollutants from central russia were more likely to be washed out en route to the arctic archipelago. because of the precipitation, only pollutions originating in central russia that existed at a higher atmospheric level were likely to be transported to the arctic through free troposphere-level transport. however, there was no correlation with air mass back-trajectories and ebc concentrations, suggesting that the contribution of longrange transport might be not significant, while local emissions might be responsible for the elevated ebc observed at the ny-ålesund community. conclusions higher concentrations of ebc were observed within nyålesund compared with measurements outside the settlement and these were attributed to local emissions. it is estimated that about 60�70% of ebc in ny-ålesund was associated with local emissions, whereas emissions from outside the arctic had less impact on local bc concentrations as a result of precipitation scavenging (stohl 2006). additionally, meteorological parameters appear to be of minor importance and could only explain 19% the observed ebc variability. the average emission rate at ny-ålesund was 8.1 g h �1 , equivalent to the bc emissions from about five light duty vehicles, or half the bc emissions from a bus, in constant operation. our modelling results indicate that bc dry deposition from local emissions at ny-ålesund was 0.0�1.8 ng m�2 h�1, and wet deposition was 0.0 to 9.6 ng m �2 h �1 within 10 km. dispersion and deposition patterns at ny-ålesund suggested that local emissions decreased to 20% within 10 km and plumes tended to affect the area to the south of the settlement. overall, the limited data from this study suggested that local emissions made a major contribution to ebc concentrations at ny-ålesund within 10 km. even though zeppelin station is located 474 m a.s.l, it is still influenced by ship emissions during summer (eckhardt et al. 2013). researchers aiming to study pristine environments in the arctic should consider the effects of these local emissions on air quality. acknowledgements this work was funded by the national natural science foundation of china (grant no. 41105094) and the scientific research foundation of third institute of oceanography, state oceanic administration of china (grant no. 2011004). the chinese arctic and antarctic administration of state oceanic administration supported field accommodations at yrs. the authors thanks w. li for technical assistance and l. chen for encouragement. the authors are also grateful for a full-time graduate assistantship provided by rutgers university that supported the continuation and completion of this research. we gratefully acknowledge the us national oceanic and atmospheric administration’s air resources laboratory for providing the hysplit transport and dispersion model, and ecmwf and ncar/ncep for providing the meteorological data freely. we thank elisabeth bjerke råstad at kings bay as for supplying the harbour log. we thank the two reviewers for their valuable comments on this manuscript. summertime anthropogenic emissions and atmospheric black carbon j. zhan & y. gao 10 (page number not for citation purpose) citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 references barrie l.a. 1996. occurrence and trends of pollution in the arctic troposphere. in e. wolff & r.c. bales (eds.): chemical exchange between the atmosphere and polar snow. pp. 93�130. new york: springer. bourgeois q. & bey i. 2011. pollution transport efficiency toward the arctic: sensitivity to aerosol scavenging and source regions. journal of geophysical research*atmospheres 116, d08213, doi: 10.1029/2010jd015096. corbett j.j., lack d.a., winebrake j.j., harder s., silberman j.a. & gold m. 2010. arctic shipping emissions inventories and future scenarios. atmospheric chemistry and physics 10, 9689�9704. dalsøren s.b., endresen ø., isaksen i.s.a., gravir g. & sørgård e. 2007. environmental impacts of the expected increase in sea transportation, with a particular focus on oil and gas scenarios for norway and northwest russia. journal of geophysical research*atmospheres 112, d02310, doi: 10.1029/ 2005jd006927. deangelo b.e. 2011. an assessment of emissions and mitigation options for black carbon for the arctic council. technical report of the arctic council task force on short-lived climate forcers. tromsø: arctic council. devasthale a., willén u., karlsson k.-g. & jones c.g. 2010. quantifying the clear-sky temperature inversion frequency and strength over the arctic ocean during summer and winter seasons from airs profiles. atmospheric chemistry and physics 10, 5565�5572. di liberto l., angelini f., pietroni i., cairo f., di donfrancesco g., viola a., argentini s., fierli f., gobbi g., maturilli m., neuber r. & snels1 m. 2012. estimate of the arctic convective boundary layer height from lidar observations: a case study. advances in meteorology 2012, 851927, doi: 10. 1155/2012/851927. doherty s.j., warren s.g., grenfell t.c., clarke a.d. & brandt r.e. 2010. light-absorbing impurities in arctic snow. atmospheric chemistry and physics 10, 11647�11680. draxler r.r. & hess g.d. 1998. an overview of the hysplit_4 modelling system for trajectories, dispersion, and deposition. australian meteorological magazine 47, 295�308. eckhardt s., hermansen o., grythe h., fiebig m., stebel k., cassiani m., baecklund a. & stohl a. 2013. the influence of cruise ship emissions on air pollution in svalbard*a harbinger of a more polluted arctic? atmospheric chemistry and physics 13, 8401�8409. eleftheriadis k., vratolis s. & nyeki s. 2009. aerosol black carbon in the european arctic: measurements at zeppelin station, ny-ålesund, svalbard from 1998�2007. geophysical research letters 36, l02809, doi: 10.1029/2008gl035741. flanner m.g., zender c.s., hess p.g., mahowald n.m., painter t.h., ramanathan v. & rasch p.j. 2009. springtime warming and reduced snow cover from carbonaceous particles. atmospheric chemistry and physics 9, 2481�2497. granier c., niemeier u., jungclaus j.h., emmons l., hess p., lamarque j.f., walters s., & brasseur g.p. 2006. ozone pollution from future ship traffic in the arctic northern passages. geophysical research letters 33, l13807, doi: 10. 1029/2006gl026180. hadley o.l. & kirchstetter t.w. 2012. black-carbon reduction of snow albedo. nature climate change 2, 437�440. hansen a.d.a., turner j.r. & allen g.a. 2007. an algorithm to compensate aethalometertm data for the effects of optical shadowing and scattering. paper presented at the 5th asian aerosol conference. 26�29 august, kaohsiung, taiwan. hegg d.a., clarke a.d., doherty s.j. & ström j. 2011. measurements of black carbon aerosol washout ratio on svalbard. tellus series b 63, 891�900. heintzenberg j. & leck c. 1994. seasonal variation of the atmospheric aerosol near the top of the marine boundary layer over spitsbergen related to the arctic sulphur cycle. tellus series b 46, 52�67. held a., orsini d.a., vaattovaara p., tjernström m. & leck c. 2011. near-surface profiles of aerosol number concentration and temperature over the arctic ocean. atmospheric measurement techniques 4, 1603�1616. hermansen o., wasseng j., bäcklund a., noon b., hennig t., schulze d. & barth v.l. 2011. air quality ny-ålesund. monitoring of local air quality 2008�2010. measurement results. kjeller, norway: norwegian institute for air research. hirdman d., burkhart j.f., sodemann h., eckhardt s., jefferson a., quinn p.k., sharma s., ström j. & stohl a. 2010. long-term trends of black carbon and sulphate aerosol in the arctic: changes in atmospheric transport and source region emissions. atmospheric chemistry and physics 10, 9351�9368. hirdman d., sodemann h., eckhardt s., burkhart j.f., jefferson a., mefford t., quinn p.k., sharma s., ström j. & stohl a. 2010. source identification of short-lived air pollutants in the arctic using statistical analysis of measurement data and particle dispersion model output. atmospheric chemistry and physics 10, 669�693. hopke p.k., barrie l.a., li s.m., cheng m.d., li c. & xie y. 1995. possible sources and preferred pathways for biogenic and non-sea-salt sulfur for the high arctic. journal of geophysical research*atmospheres 100, 16595�16603. huang l., gong s.l., sharma s., lavoué d. & jia c.q. 2010. a trajectory analysis of atmospheric transport of black carbon aerosols to canadian high arctic in winter and spring (1990�2005). atmospheric chemistry and physics 10, 5065�5073. jacob d.j., crawford j.h., maring h., clarke a.d., dibb j.e., emmons l.k., ferrare r.a., hostetler c.a., russell p.b., singh h.b., thompson a.m., shaw g.e., mccauley e., pederson j.r. & fisher j.a. 2010. the arctic research of the composition of the troposphere from aircraft and satellites (arctas) mission: design, execution, and first results. atmospheric chemistry and physics 10, 5191�5212. johnson m.r., devillers r.w. & thomson k.a. 2011. quantitative field measurement of soot emission from a large gas flare using sky-losa. environmental science & technology 45, 345�350. keogh d.u., kelly j., mengersen k., jayaratne r., ferreira l. & morawska l. 2010. derivation of motor vehicle tailpipe j. zhan & y. gao summertime anthropogenic emissions and atmospheric black carbon citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 particle emission factors suitable for modelling urban fleet emissions and air quality assessments. environmental science and pollution research 17, 724�739. klonecki a., hess p., emmons l., smith l., orlando j. & blake d. 2003. seasonal changes in the transport of pollutants into the arctic troposphere-model study. journal of geophysical research*atmospheres 108, 8367, doi: 10.1029/ 2002jd002199. koch d., bauer s.e., del genio a., faluvegi g., mcconnell j.r., menon s., miller r.l., rind d., ruedy r., schmidt g.a. & shindell d. 2011. coupled aerosol-chemistry�climate twentieth-century transient model investigation: trends in short-lived species and climate responses. journal of climate 24, 2693�2714. lack d., lerner b., granier c., baynard t., lovejoy e., massoli p., ravishankara a.r. & williams e. 2008. light absorbing carbon emissions from commercial shipping. geophysical research letters 35, l13815, doi: 10.1029/2008gl033906. law k.s. & stohl a. 2007. arctic air pollution: origins and impacts. science 315, 1537�1540. lee d.s., pitari g., grewe v., gierens k., penner j.e., petzold a., prather m.j., schumann u., bais a., berntsen t., iachetti d., lim l.l. & sausen r. 2010. transport impacts on atmosphere and climate: aviation. atmospheric environment 44, 4678�4734. liu j.f., fan s.m., horowitz l.w. & levy h. 2011. evaluation of factors controlling long-range transport of black carbon to the arctic. journal of geophysical research*atmospheres 116, d04307, doi: 10.1029/2010jd015145. nilsson e.d. & rannik ü. 2001. turbulent aerosol fluxes over the arctic ocean 1. dry deposition over sea and pack ice. journal of geophysical research*atmospheres 106, 32125� 32137. nyeki s., bauer h., puxbaum h., dye c., teinila k., hillamo r., ström j. & eleftheriadis k. 2005. comparison of black carbon concentrations derived by filter-based light transmission and thermo-optical techniques for arctic aerosol. paper presented at european aerosol conference 2005. 28 august�2 september, ghent, belgium. quinn p.k., stohl a., arneth a., berntsen t., burkhart j.f., christensen j., flanner m., kupiainen k., lihavainen h., shepherd m., shevchenko v., skov h. & vestreng v. 2011. the impact of black carbon on arctic climate. oslo: arctic monitoring and assessment programme. scott b.c. 1978. parameterization of sulfate removal by precipitation. journal of applied meteorology 17, 1375�1389. sharma s., andrews e., barrie l.a., ogren j.a. & lavoué d. 2006. variations and sources of the equivalent black carbon in the high arctic revealed by long-term observations at alert and barrow: 1989�2003. journal of geophysical research*atmospheres 111, d14208, doi: 10.1029/ 2005jd006581. sharma s., lavoué d., cachier h., barrie l.a. & gong s.l. 2004. long-term trends of the black carbon concentrations in the canadian arctic. journal of geophysical research* atmospheres 109, d15203, doi: 10.1029/2003jd004331. shindell d. & faluvegi g. 2009. climate response to regional radiative forcing during the twentieth century. nature geoscience 2, 294�300. solomon s., qin d., manning m., chen z., marquis m., averyt k.b., tignor m. & miller h.l. jr. (eds.) 2007. climate change 2007. the physical science basis: contribution of working group i to the fourth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. spackman j.r., gao r.s., neff w.d., schwarz j.p., watts l.a., fahey d.w., holloway j.s., ryerson t.b., peischl j. & brock c.a. 2010. aircraft observations of enhancement and depletion of black carbon mass in the springtime arctic. atmospheric chemistry and physics 10, 9667�9680. stohl a. 2006. characteristics of atmospheric transport into the arctic troposphere. journal of geophysical research* atmospheres 111, d11306, doi: 10.1029/2005jd006888. textor c., schulz m., guibert s., kinne s., balkanski y., bauer s., berntsen t., berglen t., boucher o., chin m., dentener f., diehl t., easter r., feichter h., fillmore d., ghan s., ginoux p., gong s., grini a., hendricks j., horowitz l., huang p., isaksen i., iversen i., kloster s., koch d., kirkevåg a., kritjansson j.e., krol m., lauer a., lamarque j.f., liu x., montanaro v., myhre g., penner j., pitari g., reddy s., seland ø., stier p., takemura t. & tie x. 2006. analysis and quantification of the diversities of aerosol life cycles within aerocom. atmospheric chemistry and physics 6, 1777�1813. tjernström m. 2005. the summer arctic boundary layer during the arctic ocean experiment 2001 (aoe-2001). boundary-layer meteorology 117, 5�36. tjernström m. & graversen r.g. 2009. the vertical structure of the lower arctic troposphere analysed from observations and the era-40 reanalysis. quarterly journal of the royal meteorological society 135, 431�443. vestreng v., kallenborn r. & økstad e. 2009. norwegian arctic climate: climate influencing emissions, scenarios and mitigation options at svalbard. oslo: climate and pollution agency. vignati e., karl m., krol m., wilson j., stier p. & cavalli f. 2010. sources of uncertainties in modelling black carbon at the global scale. atmospheric chemistry and physics 10, 2595�2611. wang q., jacobs d.j., fisher j.a., mao j., leibensperger e.m., carouge c.c., le sager p., kondo y., jimenez j.l., cubison m.j. & doherty s.j. 2011. sources of carbonaceous aerosols and deposited black carbon in the arctic in winter�spring: implications for radiative forcing. atmospheric chemistry and physics 11, 12453�12473. worthy d.e.j., trivett n.b.a., hopper j.f., bottenheim j.w. & levin i. 1994. analysis of long-range transport events at alert, northwest territories, during the polar sunrise experiment. journal of geophysical research 99, 25329�25344. wu z. & huang n.e. 2004. a study of the characteristics of white noise using the empirical mode decomposition method. proceedings of the royal society a: mathematical, physical & engineering sciences 460, 1597�1611. wu z.h. & huang n.e. 2009. ensemble empirical mode decomposition: a noise assisted data analysis method. advances in adaptive data analysis 1, doi: 10.1142/s1793536909000047. summertime anthropogenic emissions and atmospheric black carbon j. zhan & y. gao 12 (page number not for citation purpose) citation: polar research 2014, 33, 21821, http://dx.doi.org/10.3402/polar.v33.21821 http://www.polarresearch.net/index.php/polar/article/view/21821 http://dx.doi.org/10.3402/polar.v33.21821 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <feff005000440046002f0058002d00336e9662e0306e30ec30dd30fc30c87528304a30883073658766f84f5c62107528306b4f7f75283057307e30593002005000440046002f00580020306f30b030e930d530a330c330af30b3002030f330c630f330c4590963db306b304a3051308b002000490053004f00206a196e96306730593002005000440046002f0058002d003300206e9662e0306e658766f84f5c6210306b306430443066306f0020004100630072006f006200610074002030e630fc30b630ac30a430c9309253c2716730573066304f30603055304430024f5c62103057305f00200050004400460020306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200034002e003000204ee5964d30678868793a3067304d307e30593002> /ptb <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> /dan <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> /nld <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> /esp <feff0055007300650020006500730074006100730020006f007000630069006f006e00650073002000700061007200610020007200650061006c0069007a0061007200200075006e00200069006e0066006f0072006d006500200073006f0062007200650020006c006100200063006f006d007000610074006900620069006c006900640061006400200063006f006e0020005000440046002f0058002d003300200079002000670065006e006500720061007200200064006f00630075006d0065006e0074006f007300200050004400460020007300f3006c006f00200073006900200073006f006e00200063006f006d00700061007400690062006c00650073002e0020005000440046002f005800200065007300200075006e002000650073007400e1006e006400610072002000490053004f0020007000610072006100200065006c00200069006e00740065007200630061006d00620069006f00200064006500200063006f006e00740065006e00690064006f00200067007200e1006600690063006f002e002000500061007200610020006f006200740065006e006500720020006d00e1007300200069006e0066006f0072006d00610063006900f3006e00200061006300650072006300610020006400650020006300f3006d006f00200063007200650061007200200064006f00630075006d0065006e0074006f0073002000500044004600200063006f006d00700061007400690062006c0065007300200063006f006e0020005000440046002f0058002d0033002c00200063006f006e00730075006c007400650020006c006100200047007500ed0061002000640065006c0020007500730075006100720069006f0020006400650020004100630072006f006200610074002e0020004c006f007300200064006f00630075006d0065006e0074006f00730020005000440046002000730065002000700075006500640065006e00200061006200720069007200200063006f006e0020004100630072006f00620061007400200079002000520065006100640065007200200034002e003000200079002000760065007200730069006f006e0065007300200070006f00730074006500720069006f007200650073002e> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice uchida.indd 39uchida et al. 2006: polar research 25(1), 39–49 estimation of the annual primary production of the lichen cetrariella delisei in a glacier foreland in the high arctic, ny-ålesund, svalbard masaki uchida, takayuki nakatsubo, hiroshi kanda & hiroshi koizumi the fruticose lichen cetrariella delisei is among the dominant lichen species in the deglaciated high arctic areas of svalbard. as part of a study of carbon cycling in the high arctic, we aimed to estimate the primary production of lichen in a deglaciated area in ny-ålesund, svalbard (79° n), by examining the effects of abiotic factors on the net photosynthesis (pn) and dark respiration (r) rates of c. delisei. experiments were conducted in the snow-free season of 2000 using an open-fl ow gas exchange system with an infrared gas analyser. positive photosynthetic activities were observed on rainy days or soon after rainfall when the thallus water content was high, whereas photosynthetic activities dropped below the detectable limit on clear days because of the low thallus water content. under a suffi ciently high thallus water content and close to light saturation, pn was nearly constant over a wide temperature range of 4 20 °c, while r increased with increasing temperature. we constructed a model for estimating the net primary production (npp) of lichen based on the relationships between abiotic factors and the co2 exchange rate. the mean, minimum and maximum npp values in the snow-free season, estimated using meteorological data obtained from 1995–2003, were 5.1, 1.0 and 8.4 g dry wt. m–2 snow-free season–1, respectively. these results suggest that npp is highly variable and the contribution of lichen to carbon input is small compared with that of vascular plants and mosses in the study site. m. uchida & h. kanda, national institute of polar research, kaga 1-chome, itabashi-ku, tokyo 173-8515, japan; t. nakatsubo, dept. of environmental dynamics and management, graduate school of biosphere science, hiroshima university, kagamiyama 1-7-1, higashi-hiroshima 739-8521, japan; h. koizumi, river basin research center, gifu university, yanagido 1-1, gifu 501-1193, japan. a signifi cant temperature increase in arctic terrestrial ecosystems was observed during the 20th century (ipcc 2001). although a number of recent works based on solar activity have predicted a decline in temperature over the next few centuries (for example, perry & hsu 2000), the intergovernmental panel on climate change (ipcc; 2001) projected that the globally averaged surface temperature will increase by 1.4 to 5.8 °c from 1990 to 2100, and this is expected to be most pronounced in high northern latitudes. moreover, it has also been shown that temperature increases give rise to changes in snow cover, vegetation and permafrost (cornelissen et al. 2001; ipcc 2001; acia 2004). since carbon cycling in arctic terrestrial ecosystems might be temperature limited, these areas are likely to intensely suffer the direct and indirect effects of global warming (for exam40 annual primary production of the lichen cetrariella delisei ple, hobbie 1999). lichens play an important role in arctic terrestrial ecosystems (alexandrova 1970; williams et al. 1978; tenhunen et al. 1992), and those living on ground surfaces are an important interface controlling the transfer of energy and materials such as carbon, nutrients and water (kershaw & field 1975; tenhunen et al. 1992). in addition, some lichens such as cetraria and cladonia spp. are the main forage of reindeer, especially in winter (boertje 1984; chernov 1985; cooper & wookey 2001). understanding lichen production and/or growth rates is important in clarifying the role of lichen in arctic and antarctic ecosystems. a number of methods have been applied to studies of longterm production, such as direct (lange 2000; schroeter et al. 2000) and indirect measurements (kappen et al. 1991; friedmann et al. 1993). using indirect measurements, the long-term production of lichens was recently estimated using a threedimensional surface plot determined by measuring co2 exchange in the laboratory or directly at the study site (kappen 1993, 2000; schroeter et al. 1993; schlensog et al. 1997; green et al. 1999). models and direct measurement techniques for examining long-term variations in lichen production have also been developed (kappen et al. 1991; friedmann et al. 1993; schroeter et al. 1995; lange 2000). for example, friedmann et al. (1993) constructed a straightforward simulation model of co2 exchange for antarctic cryptoendolithic microorganisms and estimated their annual gross production and net photosynthetic gain over three years. their results indicate that annual gross production and net photosynthetic gain vary widely between years. in polar ecosystems, where temperatures and precipitation are highly variable within and between years, the annual production of poikilohydric plants might also vary widely from year to year (for example, schroeter et al. 2000; uchida et al. 2002). longterm monitoring and/or estimations are therefore needed to understand lichen production in polar ecosystems. as part of a study on carbon cycling in a glacier foreland in ny-ålesund, svalbard (see also nakatsubo et al. 1998; muraoka et al. 2002), we examined the effects of abiotic factors on the net photosynthesis (pn) and dark respiration (r) rates of the dominant fruticose lichen cetrariella delisei (bory ex schaer.) kärnefelt and thell (= cetraria delisei (bory ex schaerer) nyl.). we also constructed a model for estimating lichen production based on meteorological data. using this model, the yearly variation in the net primary production of lichen was estimated for the past nine years (1995–2003), and the impact of climatic warming on the carbon balance of lichen was examined. materials and methods study site the study was located in the glacier foreland of austre brøggerbreen (east brøgger glacier; 79° n, 12° e), 2 km south-west of ny-ålesund, svalbard. from 1995 to 1998, the mean annual air temperature was –5.5 °c and the amount of precipitation was 362 mm in this area. four permanent plots (sites 1, 2, 3 and 4) were established in 1994 along the primary successional series of the deglaciated area (nakatsubo et al. 1998; kume et al. 1999). lichen thalli were collected from sites 3 and 4, which represent the later stage of succession. site 3 was characterized by a patterned ground composed of small high-centred polygons. a mixed community of bryophytes and vascular plants (mv) covered the marginal part of these polygons, whereas the central part consisted of almost bare ground (bg). site 4 was similar to site 3 except that black biological crust and lichens (cl) covered the entire central part of the polygons. at site 3, the percent coverage of mv, cl and bg was 53, 30 and 17 %, respectively, while at site 4 the coverage of mv and cl was 45 and 55 %, respectively (nakatsubo et al. 1998). the dominant moss and vascular plant species at the sites were sanionia uncinata (hedw.) loeske and salix polaris wahlenb, respectively. the dominant lichen was c. delisei, which consists of an irregular branched thallus and often forms small cushions (sommerkorn 2000). gas exchange measurements for gas exchange measurements, pure stands of c. delisei (φ = 6.5 cm) were collected from colonies almost every day from 27 july to 12 august 2000. three thalli were used per measurement; after the lower black portions were discarded the remaining portions (about 10 mm thick) were placed in a covered plastic dish in the fi eld. samples were brought to the nearby laboratory and 41uchida et al. 2006: polar research 25(1), 39–49 weighed to determine the in situ water content. co2 exchange was measured in the laboratory using an open-fl ow gas exchange system with an infrared gas analyzer (irga) (li-6252, li-cor, ne, usa). a detailed description of this system and the irga calibration method are described in uchida et al. (2002). the plastic dishes holding the samples were enclosed in a cylindrical chamber (φ = 7.0 cm, height = 3.5 cm) into which a thermo couple sensor was inserted to monitor thallus temperature. the chamber was submerged in water to maintain a constant thallus temperature within an accuracy of ± 0.2 °c. ambient air containing about 365 380 ppmv co2 was introduced into the system at a rate of 300 ml min–1 and a light source was supplied in the form of a 700 w metal halide lamp (m700ls/bu, iwasakidenki, tokyo). unless otherwise noted, the temperature in the chamber and photosynthetic photon fl ux density (ppfd) were controlled to 12 ± 0.2 °c and 800 ± 30 µmol photons m–2 s–1, respectively. the effect of thallus water content on pn and r were determined by examining pn and r rates with drying over a period of about 10 hours. two moistened thallus samples were collected after rainfall and wetted with distilled water to produce the maximum water content. they were then kept in petri dishes for six hours prior to the gas exchange measurements to allow adaptation and to avoid possible resaturation respiration (smith & molesworth 1973). after obtaining the co2 exchange rate measurements, the samples were taken out of the chamber and weighed to obtain their fresh weights. they were then air-dried for 10 min to 2 h at which point a second co2 exchange rate was determined. these procedures were repeated until the pn and r rates dropped below the detection limit of the irga. after completing the gas exchange measurements, the samples were dried to a constant weight at 80 °c to obtain their dry weights. the water content (%) of the samples was expressed as follows: water content (%) = ((fresh wt – dry wt) / dry wt) × 100 the high water content determined in this study included not only the water contained in the thallus tissue but also the water adhering to the tissue. to study the effect of temperature and light incidence on pn and r, six samples were collected and optimally hydrated with distilled water to maintain high pn activity. they were then kept in petri dishes for six hours before analysis. three samples were used for measurement of the light– pn curve and the remaining three samples were used for investigation of the temperature–pn and temperature–r curves. to examine the relationship between ppfd (0 800 µmol photons m-2 s-1) and pn, the incident ppfd in the chamber was reduced using translucent polyethylene sheets or black screens. triplicate samples were illuminated at each level of ppfd for at least 3 min before measuring pn. to determine the temperature dependencies of pn and r, the temperature in the chamber was decreased from 20 to 4 °c at 3 5 °c intervals. thallus temperature was controlled by changing the temperature in the water bath. about 5 6 h were required to obtain the temperature–pn and temperature–r curves. carbon concentration five live thallus portions (about 7 mm thick) were collected from site 3 in august 2003. they were then air-dried prior to being transported to japan for carbon concentration measurements using a cn-analyzer (yanaco mt-5, yanagimoto co. ltd, kyoto). climatic data during the snow-free season of 2000 (from 4 july to 20 august), thallus temperature, ppfd and radiation were recorded at site 3. hourly thallus temperatures (at about 5 mm deep) were measured using a data logger with a thermocouple sensor (l822, unipulse inc., tokyo). at the same time, ppfd was measured at 10 minute intervals using a data logger (kadec-up, kona system, sapporo, japan) with a quantum sensor (li-190sa, li-cor). from 7 to 19 august 2000, global solar radiation was also recorded at 10 minute intervals using a data logger with a radiation sensor (pcm-01, prede, tokyo). climatic data (hourly mean values of minute by minute global radiation data and precipitation per every 12 hours) in ny-ålesund from 1995 to 2003 were provided by the alfred wegener institute, potsdam, germany, and the norwegian meteorological institute. 42 annual primary production of the lichen cetrariella delisei estimation of net primary production of c. delisei the net primary production (nppwt) of c. delisei was estimated from photosynthetic and respiration characteristics (figs. 1, 2), biomass, ppfd and vegetation temperature according to uchida et al. 2002. the basic assumption of the model is that the photosynthetic and dark respiration rates in the fi eld are primarily dependent on the water content and secondarily on the temperature and ppfd. the net photosynthetic rate at w % of thallus water content under 12 °c and 800 µmol photons m–2 s–1 (pn(w)) was given by the following formula, which was derived from the data shown in fig. 2: pn(w) = –2.21 × 10–6w2 + 1.31 × 10–3w – 0.0167 (1) the dark respiration rate at w % under 12 °c (r(w)) was given by the following: r(w) = –7.31 × 10–2 + 5.08 × 10–2 × log(w) (2) the net photosynthetic rate at w % of thallus water content, temperature t (°c) and 800 µmol photons m–2 s–1 (pn(w, t)) was expressed as follows: pn(w, t) = pn(w) (at2 + bt + c) (3) where a, b and c are coeffi cients of the temperature–pn curve (fig. 1b) (–0.0013, 0.0114 and 1.0401, respectively). -0.1 0 0.1 0.2 0.3 0 200 400 600 800 1000 ( m gc o 2 -c g -1 d ry w t. h1 ) ppfd (µmol photons m-2 s-1) n et c o 2 ex ch an ge r2 = 0.96 0 0.1 0.2 0.3 0 5 10 15 20 25 ( m gc o 2 c g -1 d ry w t. h1 ) n et c o 2 ex ch an ge temperature (°c) r2 = 0.65 0 0.1 0.2 0 5 10 15 20 25 temperature (°c) ( m gc o 2 -c g -1 d ry w t. h1 ) r2 = 0.97 d ar k re sp ira tio n ra te (a) (b) (c) fig. 1. effect of light on the net photosynthetic (pn) rate and temperature on the net photosynthetic (pn) and dark respiration (r) rates of cetrariella delisei. (a) light–pn curve. temperature: 12 ± 0.2 °c; water content: 270 ± 30 %. (b) temperature–pn curve. ppfd: 800 ± 30 µmol photons m–2 s–1; water content: 358 ± 17 %. (c) temperature–r curve. water content: 358 ± 17 %. values represent the mean of three samples plus the standard deviation (sd). -0.1 0 0.1 0.2 0.3 pn r 0 100 200 300 n et c o 2 e xc ha ng e ( m g c o 2 -c g -1 d ry w t. h -1 ) r2 = 0.70 r2 = 0.69 water content (%) fig. 2. effect of water content on the net photosynthetic (pn) and dark respiration (r) rates of cetrariella delisei measured at the fi eld water content (n = 45). temperature: 12 ± 0.2 °c; ppfd: 800 ± 30 µmol photons m–2 s–1. 43uchida et al. 2006: polar research 25(1), 39–49 the dark respiration rate at t (°c) and w % of thallus water content (r(w, t)) was expressed as follows: r(w, t) = r (w)q10(t–12)/10 (4) the q10 value calculated from the temperature–r curve (fig. 1c) was 2.3. the effect of ppfd on the photosynthetic rate was calculated according to thornley (1976): pg(w, t, i) = (5) αi + pmax – {(αi + pmax)2 – 4θαipmax}0.5 × pg(w, t)————————————————2θ pn(w, t, i) = pg(w, t, i) – r(w, t), (6) where pn(w, t, i) (mgco2 – c m–2 h–1) is the net photosynthetic rate at w % of thallus water content, t (°c) and i µmol photons m–2 s–1; pg(w, t, i) is the gross photosynthetic rate at w % of thallus water content, t (°c) and i µmol photons m–2 s–1 ; α is the initial slope of the ppfd–pg curve; pmax is the asymptotic value of pg at light saturation; θ is a dimensionless constant (0.8); t is the hourly thallus temperature; and i is the hourly ppfd in the fi eld. to determine α and pmax, the relationship between ppfd and pn was recalculated from the relationship between ppfd and relative pg. equation (5) was then fi tted to the relationship and α and pmax were determined as 0.0021 and 1.29, respectively. daily net production was expressed by the following: nppwt = σpn(w, t, i) = σ (pg(w, t, i) – r(w, t)) (7) to estimate the nppwt of the past nine years (1995–2003), thallus temperature, ppfd, and thallus water content were estimated from the meteorological records of ny-ålesund according to uchida et al. (2002). the relationships between radiation and thallus temperature, radiation and ppfd, and precipitation and thallus water content were calculated mainly from data of the snowfree season of 2000. these relationships were expressed as follows: t = 0.0368rad + 3.928 r 2 = 0.62 (8) i = 2.197rad r 2 = 0.98 (9) pr > 8.1 w = 358 8.1 ≥ pr ≥ 0.1 w = 333.7log(pr+1) + 37.6 (10) r 2 = 0.66 pr < 0.1 pn = r = 0 where rad is the global radiation and pr is the precipitation per 12 h. in this study, we assumed that the maximum water holding capacity of the thallus (358 %) was derived when pr was in excess of 8.1 mm (eq. 10). on the other hand, the rates of pn and r were assumed to be zero when no signifi cant precipitation was observed. nppwt in the snow-free season, which started on the fi rst rainy day of that season and ended on the fi rst snowy day in late august or september, was calculated using equations (1)–(10) and the meteorological records from 1995 to 2003. to compare the obtained result with those of previous studies, the calculated nppwt (mgco2–c g–1 dry wt. season–1) was converted to dry matter production per area using the carbon concentration (44.4 %) and biomass of a pure community of standing c. delisei in this area (95 g dry wt. m–2). effects of changes in temperature on net primary production to clarify the effects of increasing temperature on lichen production, we estimated the potential production of c. delisei during the snow-free season. we assumed that the growing season does not change because it is diffi cult to estimate the exact timing and period of thawing. the temperature increase in the model was established as +3 to +6 °c. results and discussion effects of abiotic factors on photosynthesis and respiration at a constant temperature (12 °c), the thallus photosynthetic response to light incidence exhibited saturation (fig. 1a). the light compensation point occurred at about 120 µmol photons m–2 s–1 and light saturation appeared at over 800 µmol photons m–2 s–1. these values are similar to, or somewhat higher, than those previously reported for arctic and antarctic fruticose lichens in open habitats (kappen 1983; ino 1985; schipperges 1992). the response curve of pn to lichen temperature was typically broad, and pn decreased gradually with increasing temperature in a temperature range of 4 to 20 °c (fig. 1b). the optimal 44 annual primary production of the lichen cetrariella delisei temperature for net photosynthesis was estimated as ≤ 4°c. sommerkorn (2000) reported that the optimum temperature for net photosynthesis of c. delisei at 500 µmol photons m–2 s–1, 350 ppm co2, is 12 °c. a similar optimum temperature was reported for other fruticose lichens (e.g. kappen et al. 1995; schroeter et al. 1995; sommerkorn 2000). on the other hand, a low temperature optimum was previously reported for c. delisei and c. nivalis (schipperges 1992), neuropogon acromelanos (kappen 1993) and usnea and umbilicaria spp. (ino 1985). kappen (1983) indicated that physiological activity differs between light and shade forms, even within the same lichen species. some lichen species might alter their physiological activity under different environmental conditions. the r of c. delisei increased with temperature up to 20 °c (fig. 1c), and the q10 value, which describes the proportional changes in rates with 10 °c changes in temperature, of r was 2.3 (n = 3). although the pn of c. delisei dropped below the detectable limit at a thallus water content of 25 %, it increased rapidly from a water content of 25 to about 100 %. the maximum pn was maintained at a water content of about 300 % (fig. 3), which is similar to the optimum water content of other lichens from cold regions (macfarlane & kershaw 1980; smith & gremmen 2001). on the other hand, r increased gradually with increasing thallus water content. the potential rates of net photosynthesis (pnpot) and dark respiration (rpot), which were determined from the fi eld water content under constant temperature and light conditions (12 °c and 800 ± 30 µmol photons m–2 s–1), showed the importance of rainfall on physiological activity (fig. 4a). pnpot and rpot were relatively high on rainy days when the thallus water content was usually within a range of 50 to 270 % (fig. 4b), whereas they were relatively low on snowy days (from 27 july to 1 august). a higher thallus water content under snow was previously shown for c. delisei (sommerkorn 2000) and usnea sphacelata (kappen 1993). it is suggested that lichens can take up water vapour from snow crystals that touch or surround the thallus (kappen & schroeter 1997). however, it has also been reported that thallus water content varies widely in the fi eld on snowy days (kappen & breuer 1991). although more than 3 mm rainfall was observed on 2 and 3 august, thallus water -0.1 0 0.1 0.2 0 100 200 300 400 n et c o 2 e xc ha ng e water content (%) p n r (m gc o 2 -c g -1 d ry w t. h1 ) r2 = 0.91 r2 = 0.82 ○○ fig. 3. net photosynthetic (pn) and dark respiration (r) rates of cetrariella delisei at different water contents. the thallus was fully saturated then pn and water content were measured as the tissue desiccated. temperature: 12 ± 0.2 °c; ppfd: 800 ± 30 µmol photons m–2 s–1. 0 50 100 150 200 250 300 w at er c on te nt ( % ) 25 30 4 9 14 july august 0 2 4 6 8 10 p re ci pi ta tio n (m m ) -0.1 0 0.1 0.2 0.3 pn r n et c o 2 e xc ha ng e 25 30 4 9 14 july august ( m g c o 2 -c g -1 d ry w t. h1 ) ● water content snow (a) (b) rain fig. 4. (a) net photosynthetic (pn) and dark respiration (r) rates of cetrariella delisei at the fi eld water content. temperature: 12 ± 0.2 °c; ppfd: 800 ± 30 µmol photons m–2 s–1. values represent the mean of three samples plus the sd. (b) changes in thallus water content (at a depth of about 7 mm) in the colony of cetrariella delisei. values represent the mean of three samples plus the sd. 45uchida et al. 2006: polar research 25(1), 39–49 content was relatively low on these days (fig. 4b). this is because the thalli were collected before rainfall or at least 12 h after rainfall. thallus water content decreased rapidly after rainfall resulting in a decrease in pnpot. when the thallus dried out, the pnpot dropped below the detectable limit of the irga. figure 2 shows the relationship between pnpot, rpot and water content in the fi eld; the shape of the curve was similar to that obtained in the laboratory (fig. 3). however, the pn rates at the same water content were higher in the fi eld (fig. 2) than in the laboratory (fig. 3). the reason for this is unclear, but one possible explanation is the difference in photosynthetic activity caused, for example, by feeding and/ or the trampling effect of reindeer (cooper et al. 2001; cooper & wookey 2001), acclimation and thallus shape. estimation of net primary production to validate the model, we fi rst estimated the daily nppwt in the growing season (27 july – 12 august 2000) using equations (1)–(6) and the data of thallus water content, ppfd and thallus temperature recorded in the fi eld. the daily nppwt values ranged between 0.01 and 0.76 mgco2–c g–1 dry wt. day–1 (fig. 5), which was much smaller than those of sanionia uncinata in the same site (0.0 3.61 mgco2–c g–1 dry wt. day–1; uchida et al. 2002). the total nppwt for the study period (27 july to 12 august) was estimated as 15.4 mgco2–c g–1 dry wt. this value was more than twice the nppwt value obtained from the daily pnpot and rpot data in fig. 4a using equation (3)– (6) and the microclimate data (6.4 mgco2–c g–1 dry wt.). one possible reason for this discrepancy might be differences in the relationship between the amount of snowfall and thallus water content and between rainfall and thallus water content. kappen & breuer (1991) reported that thallus water content varies greatly during and after snowfall, probably as a result of the unavailability of snow as a direct water source for lichens. when excluding the snowy period, the total nppwt for the study period (4.5 mgco2–c g–1 dry wt.) was not so different from the value obtained from the pnpot and rpot data in fig. 4a using equations (3)– (6) (3.4 mgco2–c g–1 dry wt.). it was previously reported that the production of c. delisei incubated in the fi eld on brøggerhalvøya (the peninsula on which our own fi eld sites were located) in 1999 was 6.2 % of the dry mass (cooper & wookey 2001). the percent increase in dry mass in 1999 estimated in our study was 5.3 % (npp: 5.0 g m–2 / biomass 95 g m–2 × 100), which was slightly lower than the value obtained by cooper & wookey. the difference between their value and our estimation could be partly because we did not consider the effects of dew, fog, melting snow and accuracy of our model. in the negev desert, dewfalls are frequent and are important for lichen production (kappen et al. 1979). however, the effect of water uptake by dewfall might not be large on clear days in nyålesund. diurnal courses of c. delisei thallus water content showed that it is maintained around 30 % (schipperges 1992). we also observed that the relative humidity at a height of 15 cm from the soil surface rarely exceeded 90 % on clear days in 2002 (data not shown). on the other hand, the climate condition of ny-ålesund easily results in frequent fogs during summer (lloyd 2001). in this study, the rain gauge sometimes detected fog as precipitation because of its high resolution (detectable limit: 0.1 mm). since foggy days not detected by the rain gauge include just three days in 2001 and one day in 2002, the contribution of fog on lichen production could be small. the accuracy of the model might also have contributed to differences in the production estimations. it is well known that interactions exist between changes in ppfd saturation and thallus water content, and changes in the optimum temperature and ppfd (kappen et al. 1991; lange 2000), but these were not considered in our model. a three-dimensional surface plot model 0 0.2 0.4 0.6 0.8 1.0 d ai ly n et p ro du ct io n july (m gc o 2 -c g -1 d ry w t. da y1 ) 25 30 5 10 august **** fig. 5. daily net primary production (npp) of cetrariella delisei. * no data. 46 annual primary production of the lichen cetrariella delisei would therefore be more accurate in estimating lichen production (e.g. schlensog et al. 1997; green et al. 1999; kappen 2000). furthermore, disturbances by reindeer might also have had an impact. cooper & wookey (2001) indicated that the growth rate of cut fruticose lichen thalli was lower than that of intact thalli. they used thalli collected from an enclosure not affected by reindeer grazing and trampling; however, we used thalli collected from areas that could have suffered from reindeer disturbances. the snowy season is an important season for lichen production (kappen 1993; kappen et al. 1995). according to a photosynthetic activity value obtained by a laboratory measurement of thallus, production of c. delisei under a spring snow cover can be considerable (sommerkorn 2000). however, continental antarctic lichens under undisturbed snow were not active as measured by a portable pam fl uorescence system (pannewitz et al. 2003). although snow is one of the major water sources for the lichens, lichens might only become active for a brief time when the snow disappeared (pannewitz et al. 2003). more fi eld investigation is needed to reveal lichen production during the snow melting period. yearly variation and impact of climate warming on net primary production the net primary production (npp) of c. delisei calculated using the model showed high yearly variation (fig. 6). the mean, minimum and maximum npp values were 5.1, 1.0 and 8.3 g dry wt. m–2 snow-free season–1, respectively. several factors could have contributed to this variability. uchida et al. (2002) suggested that poikilohydric moss production is limited by water availability because the lowest npp they recorded in 1998 corresponded to a period of low precipitation during the snow-free season. on the other hand, the difference in npp between 2001 and 2002 was small although the difference in precipitation between these two years was very large. one of the reasons for this difference could be rainfall intensity. our model assumed that the maximal thallus water content is 358 % when precipitation is over 8.1 mm per 12 hours. therefore, photosynthetic activity under a constant ppfd and temperature condition will be the same even if the amount of rainfall per 12 hours surpasses 8.1 mm. for example, on 21 july 2002, precipitation per 12 hours was 36 mm. since the thallus water holding capacity is limited, the contribution of enhanced rainfall intensity on lichen production might not be so signifi cant. even with a constant water supply, temperature and light incidence would also infl uence lichen production (uchida et al. 2002). the annual net primary production of arctic lichens reportedly ranges from 0.03 g m–2 for polar barrens on cornwallis island, canada (bliss et al. 1984), to < 5 g m–2 for wet meadows in demster and eagle creeks in alaska (wein & bliss 1974) (table 1). the mean npp value of c. delisei estimated in this study was similar to that of lichen communities on wet meadows in demster and eagle creeks (wein & bliss 1974). on the other hand, lange (2000) collected the gelatinous cyanolichen collema cristatum and incubated it in a quasi-natural habitat in the botanical garden in würzburg, germany, and estimated its 0 2 4 6 8 10 1995 1997 1999 2001 2003 year 0 50 100 150 200precipitation p re ci pi ta tio n (m m ) n et p rim ar y pr od uc tio n npp (g d ry w t. m -2 s no w -f re e se as on -1 ) fig. 6. net primary production (npp) of cetrariella delisei and the amount of precipitation during the snow-free season. 47uchida et al. 2006: polar research 25(1), 39–49 annual production as 25.8 gc m–2, which is about fi ve times higher than the average value estimated here. muraoka et al. (2002) and uchida et al. (2002) reported that the npp values of the vascular plant salix polaris and the moss sanionia uncinata at the same study site were 98 (the carbon concentration was assumed to be 50 % from van der wal et al. 2000) and 17 g dry wt. m–2 snow-free season–1, respectively. the npp of lichen is much smaller than those of these two species. although moss is also a poikilohydric plant, the average lichen production obtained here was about onethird that of moss production. this is partly due to the low photosynthetic activity of lichens. global warming is likely to be most intense at high latitudes. in this study, c. delisei showed a low optimum temperature for net photosynthesis, suggesting that temperature increases might reduce the carbon gain of lichen. to clarify the effects of increasing temperature on lichen production, we estimated the potential production of c. delisei during the snow-free season. in the simulation, although all estimated values showed positive production, a warming of + 6 °c caused a substantial decline in lichen production (table 2). this is because although the temperature response of net photosynthesis is broad, respiration rates increased with increasing temperature in our model. respiration therefore seems to be the main driver of npp change with warming. the effect of temperature acclimation on lichen production should also be considered because respiration responses in arctic and alpine plants show rapid acclimation (körner 1999). lange & green (2005) reported that some soil-crust lichen species showed seasonal changes in the temperature sensitivity of dark respiration. however, kershaw (1985) indicated that temperature acclimation differs between different populations. although further research is needed to clarify this point, it is suggested that climate warming would cause a reduction in carbon gain in some arctic lichens. on the other hand, it is also projected that global warming will cause not only a temperature increase but also a change in precipitation and the duration of snow cover. it has been predicted that global warming would cause increased rainfall in the norwegian arctic (førland & hanssen-bauer 2000). precipitation timing, duration and intensity would also impact lichen production (lange 1980; smith & gremmen 2001), so future precipitation changes are also important to consider when predicting lichen production. table 1. net annual production and phytomass of lichens in arctic regions. location vegetation type net annual production (g m–2) phytomass (g m–2) reference demster, alaska (64° n) wet meadow <5 69 wein & bliss 1974 eagle creek, alaska (65° n) wet meadow <5 25 wein & bliss 1974 stordalen, sweden (68° n) wet meadow <3 12 rosswall et al. 1975 cornwallis island, canada (74° n) polar barrens 0.03 2.9 bliss et al. 1984 devon island, canada (75° n) dwarf shrub heath 4 48 bliss 1977 devon island, canada (75° n) cushion plant–moss fellfi eld 3 49 bliss 1977 devon island, canada (75° n) cushion plant–moss fellfi eld 2 23 bliss 1977 king christian island, canada (77° n) moss–graminoid meadow <1 10 bliss & svoboda 1984 ellef ringnes island, canada (78° n) grass heath <1 29 bliss & svoboda 1984 ellef ringnes island, canada (78° n) grass heath <1 9 bliss & svoboda 1984 ny-ålesund, svalbard (79° n) cushion plant–moss heath 1.0 8.4 95 present study table 2. effect of temperature increase on the net primary production of c. delisei. year % reduction of production +3 °c +6 °c 1995 12 27 1996 14 24 1997 15 37 1998 23 55 1999 24 55 2000 12 26 2001 29 67 2002 28 67 2003 17 40 48 annual primary production of the lichen cetrariella delisei acknowledgements.—we gratefully acknowledge prof. m. inoue, akita university, for helpful advice on lichen identifi cation. we also thank yukiko bekku, tsuru university, for support during our study, as well as dr andreas herber, alfred wegener institute, potsdam, germany, and drs inger marie nordin, asta guttormsdottir and stein kristiansen, all at the norwegian meteorological institute. this study was supported by a grant-in-aid for scientifi c research from the japan society for the promotion of science. references acia (arctic climate impact assessment) 2004: impacts of a warming arctic. cambridge: cambridge university press. alexandrova, v. d. 1970: the vegetation of the tundra zones in the ussr and data about its productivity. in w. a. fuller & p. g. kevan (eds.): productivity and conservation in northern circumpolar lands. pp. 93–114. morges, switzerland: iucn. bliss, l. c. (ed.) 1977: trulove lowland, devon island, canada: a high arctic ecosystem. edmonton: university of alberta press. bliss, l. c. & svoboda, j. 1984: plant communities and plant production in the western queen elizabeth islands. holarctic ecol. 7, 325–344. bliss, l. c., svoboda, j. & bliss, d. i. 1984: polar deserts, their plant cover and plant production in the canadian high arctic. holarctic ecol. 7, 305–324. boertje, r. d. 1984: seasonal diets of the denali caribou herd, alaska. arctic 37, 161–165. chernov, y. i. (ed.) 1985: the living tundra. cambridge: cambridge university press. cooper, e. j., smith, f. m. & wookey, p. a. 2001: increased rainfall ameliorates the negative effect of trampling on the growth of high arctic forage lichens. symbiosis 31, 153– 171. cooper, e. j. & wookey, p. a. 2001: field measurements of the growth rates of forage lichens, and the implications of grazing by svalbard reindeer. symbiosis 31, 173–186. cornelissen, j. h. c., callaghan, t. v., alatalo, j. m., michelsen, a., graglia, e., hartley, a. e., hik, d. s., hob bie, s. e., press, m. c., robinson, c. h., henry, g. h. r., shaver, g. r., phoenix, g. k., gwynn jones, d., jonasson, s., chapin iii, f. s., molau, u., neill, c., lee, j. a. melillo, j. m., svein björnsson, b. & aerts, r. 2001: global change and arctic ecosystems: is lichen decline a function of increases in vascular plant biomass? j. ecol. 89, 984–994. førland, e. j. & hanssen-bauer, i. 2000: increased precipitation in the norwegian arctic: true or false? clim. change 46, 485–509. friedmann, e. i., kappen, l., meyer, m. a. & nienow, j. a. 1993: long-term productivity in the cryptoendolithic microbial community of the ross desert, antarctica. microb. ecol. 25, 51–69. green, t. g. a., schroeter, b. & sancho, l. g. 1999: plant life in antarctica. in f. i. pugnaire & f. valladares (eds.): handbook of functional plant ecology. pp. 495–543. new york: marcel dekker. hobbie, s. e. 1999: arctic ecology. in f. i. pugnaire & f. valladares (eds.): handbook of functional plant ecology. pp. 473–493. new york: marcel dekker. ino, y. 1985: comparative study of the effects of temperature on net photosynthesis and respiration in lichens from the antarctic and subalpine zones in japan. bot. mag. tokyo 98, 41–53. ipcc (intergovernmental panel on climate change) 2001: polar regions (arctic and antarctic). in j. j. mccarthy et al. (eds.): climate change 2001: impacts, adaptation, and vulnerability. pp. 801–841. cambridge: cambridge university press. kappen, l. 1983: ecology and physiology of the antarctic fruticose lichen usnea sulphurea (koenig) th. fries. polar biol. 1, 249–255. kappen, l. 1993: plant activity under snow and ice, with particular reference to lichens. arctic 46, 297–302. kappen, l. 2000: some aspects of the great success of lichens in antarctica. antarct. sci. 12, 314–324. kappen, l. & breuer, m. 1991: ecological and physiological investigations in continental antarctic cryptogams. ii. moisture relations and photosynthesis of lichens near casey station, wikes land. antarct. sci. 3, 273–278. kappen, l., breuer, m. & bölter, m. 1991: ecological and physiological investigations in continental antarctic cryptogams. 3. photosynthetic production of usnea sphacelata: durnal courses, models, and the effect of photoinhibition. polar biol. 11, 393–401. kappen, l., lange, o. l., schulze, e.-d., evenari, m. & buschbom, u. 1979: ecophysiological investigations on lichens of the negev desert. vi. annual course of the photosynthetic production of ramalina maciformis (del.) bory. flora 168, 85–108. kappen, l. & schroeter, b. 1997: activity of lichens under the infl uence of snow and ice. proc. nipr symp. polar biol. 10, 163–168. kappen, l., sommerkorn, m. & schroeter, b. 1995: carbon acquision and water relations of lichens in polar regions potentials and limitations. lichenologist 27, 531–545. kershaw, k. a. 1985: physiological ecology of lichens. cambridge: cambridge university press. kershaw, k. a. & field, g. f. 1975: studies on lichen-dominated systems. xv. the temperature and humidity profi les in a cladina alpestris mat. can. j. bot. 53, 2614–2620. körner, c. (ed.) 1999: alpine plant life: functional plant ecology of high mountain ecosystems. berlin: springer. kume, a., nakatsubo, t., bekku, y. & masuzawa, t. 1999: ecological signifi cance of different growth forms of purple saxifrage, saxifraga oppositifolia l., in the high arctic, ny-ålesund, svalbard. arct. antarct. alp. res. 31, 27–33. lange, o. l. 1980: moisture content and co2 exchange of lichens. oecologia 45, 82–87. lange, o. l. 2000: photosynthetic performance of a gelatinous lichen under temperate habitat conditions: long-term monitoring of co2 exchange of collema cristatum. bibl. lichenol. 75, 307–332. lange, o. l. & green, t. g. a. 2005: lichens show that fungi can acclimate their respiration to seasonal changes in temperature. oecologia 142, 11–19. lloyd, c. r. 2001: the measurement and modelling of the carbon dioxide exchange at a high arctic site in svalbard. glob. chang. biol. 7, 405–426. macfarlane, j. d. & kershaw, k. a. 1980: physiologicalenvironmental interactions in lichens. ix. thermal stress and lichen ecology. new phytol. 84, 669–685. muraoka, h., uchida, m., mishio, m., nakatsubo, t., kanda, h. & koizumi, h. 2002: leaf photosynthetic characteristics and net primary production of the polar willow (salix 49uchida et al. 2006: polar research 25(1), 39–49 polaris) in a high arctic polar semi-desert, ny-ålesund, svalbard. can. j. bot. 80, 1193–1202. nakatsubo, t., bekku, y., kume, a. & koizumi, h. 1998: respiration of the belowground parts of vascular plants: its contribution to total soil respiration on a successional glacier foreland in ny-ålesund, svalbard. polar res. 17, 53– 59. pannewitz, s., schlensog, m., green, t. g. a., sancho, l. g. & schroeter, b. 2003: are lichens active under snow in continental antarctica? oecologia 135, 30–38. perry, c. a. & hsu, k. j. 2000: geophysical, archaeological, and historical evidence support a solar-output model for climate change. proc. natl. acad. sci. u. s. a. 97, 12 433– 12 438. rosswall, t., veum, a. k. & kärenlampi, l. 1975: plant litter decomposition at fennoscandian tundra sites. in f. e. wielgolaski (ed.): fennoscandian tundra ecosystems. part 1: plants and microorganisms. pp. 268–278. new york: springer. schipperges, b. 1992: patterns of co2 gas-exchange and thallus water content in arctic lichens along a ridge profi le near ny-ålesund, svalbard. polar res. 11, 47–68. schlensog, m., schroeter, b., sancho, l. g., pintado, a. & kappen, l. 1997: effect of strong irradiance on photosynthetic performance of the melt-water dependent cyanobacterial lichen leptogium puberulum (collemataceae) hue from the maritime antarctic. bibl. lichenol. 67, 235–246. schroeter, b., kappen, l. & schulz, f. 1993: long-term measurements of microclimatic conditions in the fruticose lichen usnea aurantiaco-atra in the maritime antarctic. in j. cacho & d. serrat (eds): actas del v simposio de estudios antárticos, 1993. pp. 63–69. madrid: comisión interministerial de ciencia y tecnología. schroeter, b., kappen, l., schulz, f. & sancho, l. g. 2000: seasonal variation in the carbon balance of lichens in the maritime antarctic: long-term measurements of photosynthetic activity in usnea aurantiaco-arta. in w. davison et al. (eds): antarctic ecosystems: models for wider ecological understanding. pp. 258–262, christchurch: caxton press. schroeter, b., olech, m., kappen, l. & heitland, w. 1995: ecophysiological investigations of usnea antarctica in the maritime antarctic. i. annual microclimatic conditions and potential primary production. antarct. sci. 7, 251–260. smith, d. c. & molesworth, s. 1973: lichen physiology. xiii. effects of rewetting dry lichens. new phytol. 72, 525–533. smith, v. r. & gremmen, n. j. m. 2001: photosynthesis in a sub-antarctic shore-zone lichen. new phytol. 149, 291– 299. sommerkorn, m. 2000: the ability of lichens to benefi t from natural co2 enrichment under a spring snow-cover: a study with two arctic-alpine species from contrasting habitats. bibl. lichenol. 75, 365–380. tenhunen, j. d., lange, o. l., hahn, s., siegwolf, r. & oberbauer, s. f. 1992: the ecosystem role of poikilohydric tundra plants. in f. s. chapin iii et al. (eds.): arctic ecosystems in a changing climate. pp. 213–237. san diego: academic press. thornley, j. h. m. 1976: a survey of some light-response curves. in j. h. m. thornley (ed.): mathematical models in plant physiology. pp. 93–95. london: academic press. uchida, m., muraoka, h., nakatsubo, t., bekku, y., ueno, t., kanda, h. & koizumi, h. 2002: net photosynthesis, respiration, and production of the moss sanionia uncinata on a glacier foreland in the high arctic, ny-ålesund, svalbard. arct. antarct. alp. res. 34, 287–292. van der wal, r., madan, n., van lieshout, s., dormann, c., langvatn, r. & albon, s. d. 2000: trading forage quality for quantity? plant phenology and patch choice by svalbard reindeer. oecologia 123, 108–115. wein, r. w. & bliss, l. c. 1974: primary production in arctic cottongrass tussock tundra communities. arct. alp. res. 6, 261–274. williams, m. e., rudolph, e. d., schofi eld, e. a. & prasher, d. c. 1978: the role of lichens in the structure, productivity, and mineral cycling of the wet coastal alaskan tundra. in l. l. tieszen (ed.): vegetation and production ecology of an alaskan arctic tundra. pp. 185–206. new york: springer. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice por_009.fm 88 polar research 26 (2007) 88 – 89 © 2007 the author book review review of arctic animals and their adaptations to life on the edge , by arnoldus schytte blix (2005). trondheim: tapir academic press. 296 pp. isbn 82-519-2050-7. conceived in order to provide students and those interested in the arctic with a comprehensive overview of arctic ecosystems, processes and animal adaptations to life in the cold, this textbook of 10 chapters draws on the 30 year research experience of dr arnoldus blix, an accomplished arctic physiologist. topics covered by the book range from the climate, oceanography and ecology of the arctic region to the distribution, behaviour and life cycles of marine and terrestrial invertebrates and through to higher resident marine and terrestrial predators. the textbook begins with a poetic definition of the arctic— describing it as the region under arctos, the polar star— and thereby setting the scene for the rest of the text, which combines concise descriptions of arctic processes and species distributions interspersed with accounts of the author’s research experience and almost 200 illustrations. in the first chapter we are introduced to the physical characteristics of the arctic. this cold, dry and windy polar region experiences large annual fluctuations in day length and temperature. increasing ultraviolet light enters the arctic atmosphere through a diminishing ozone layer. sea ice fluctuates in thickness throughout the region, with the centre of the arctic consisting of “interlocking ice floes slowly circulating with the ocean’s surface currents” (p. 27). current flow, the position of the polar front and the extent of sea ice all influence primary production and the distribution of zooplankton and higher predators, such as seabirds and marine mammals, in the various arctic seas. ultimately, it is the high level of variability in physical conditions, notably the rapid change in photoperiod, which largely determines the adaptations of both animals and plants to life in the arctic. although this section provides a detailed backdrop to conditions encountered by life in the arctic, there is little information on current climatic changes occurring in the region, such as the diminished extent and earlier break-up of sea ice. comprehensive descriptions of the ecology and distribution of marine organisms, terrestrial birds and mammals, and a brief section on the far-ranging summer migrant seabirds and mammals of the arctic comprise the following sections. here we also gain many insights into the behaviour of arctic animals, such as the extensive migrations of reindeer, the complex interactions between musk oxen and predatory wolves, and the building of ice lairs by ringed seals to provide protection from predators and weather. each species description is accompanied by an informative distribution map. the last portion of the book, taking up almost one-third of the volume, discusses the many and varied physiological adaptations that allow arctic animals to cope with life on the edge. adaptations evolved by arctic animals to combat extremes in cold include: the seasonal deposition of fat stores in pinnipeds and whales; heat-producing brown fat layers in musk oxen and reindeer; and the increased insulating properties of long, thick polar bear fur. a profound tolerance to hypothermia is evident in newborn lemmings and snowy owl chicks, whereas young seals manage exposure to extreme cold at birth through a combination of large body size and/or brown correspondence mary-anne lea, antarctic wildlife research unit, university of tasmania, box 252-05, hobart, tasmania, australia. email: ma_lea@utas.edu.au book review polar research 26 (2007) 88 – 89 © 2007 the author 89 fat reserves or thick blubber layers. throughout this chapter, research conducted by the author and his colleagues provides many interesting examples of astounding adaptations ranging from the hibernation and starvation of polar bears and ground squirrels to the rapid changes in heart rate of diving seals. complex concepts are clearly explained and are aided by the inclusion of well-described figures. in conclusion, this text summarizes a plethora of historic and current arctic information in a readable and often colourful writing style. it should be a welcome addition to the libraries of students, scientists and visitors to the arctic alike. mary-anne lea antarctic wildlife research unit, university of tasmania, hobart, tasmania, australia using multiple data sources to enhance photogrammetry for mapping antarctic terrain adrian j . fox fox, a. j. 1995: using multiple data sources to enhance photogrammetry for mapping antarctic terrain. polar research 14(3), 311-321. extensive aerial photography cover is available for parts of the british antarctic territory, but the characteristics of the photography, combined with the sparsity of ground control information and rugged snow-covered terrain, make photogrammetric mapping techniques difficult to apply. this paper shows. by reference to a new 1:50,000 scale topographic map of part of the antarctic peninsula, how merging topographic data from various sources in a gis environment can make photogrammetric mapping more effective. information sources used in the map compilation include three types of aerial photography. geo referenced satellite imagery, surveyed points in a control network and satellite image-derived control points. a shape-from-shading algorithm was used to generate contours for snowfields where absence of surface detail prevented photogrammetric contouring. a horizontal and vertical accuracy of better than + 5 m was achieved in orientation of photography covering almost all of the map area. such errors have allowed the construction of an accurate large-scale map for an area where previous mapping had been restricted to medium and small scales. adrian 1. fox, british antarctic survey, natural environment research council. high cross: madingley road. cambridge cb3 oet, u k . introduction despite extensive aerial photography cover of parts of the british antarctic territory (bat), rigorous photogrammetric compilation of large scale topographic maps is precluded for many areas because of inadequate ground control. the acquisition of comprehensive new geodetic data is unlikely, even with the application of gps survey techniques in bat, due to the large areas to be covered, difficult access and severe climate. furthermore, the polar terrain can make photo grammetric techniques difficult to apply. for example, problems are encountered during the construction of photogrammetric blocks across large snowfields where suitable pass-point fea tures are absent; plotting contours on snow-cov ered areas is difficult because of insufficient surface detail for stereo-matching; areas of dead ground on the photographs, due to the rugged terrain and low flying heights, are common. these difficulties have hindered large-scale topographic mapping of bat in the past, and the largest scale maps available with any extensive coverage are at 1 : 250,000 scale. to enable the compilation of high quality, large-scale maps it is necessary to develop methods for more effective use of aerial pho tography. regarding digital, photogrammetrically derived topographic data simply as “3-d digi tising” (rather than as the principal map com pilation material) allows the merging of photogrammetric map data with other remote sensing data sources within a gis environment. in referring to the compilation of a 1 : 50,000 scale map of wright peninsula (bas scistamap series, sheet l b ) , this paper shows how merging several data sources can enhance photogram metric techniques and enable map compilation for an area where effective topographic mapping would not otherwise be possible. it is hoped that the techniques discussed may have wider appli cation in other areas which present similar obstacles t o large-scale topographic mapping. description of project wright peninsula is an ice-covered peninsula on the eastern side of adelaide island, bat (figs. 1 and 2 ) . rothera, the main british antarctic survey (bas) research station on the antarctic peninsula, is situated on a low, rocky promontory at the southeastern tip of wright peninsula. the 318 a . j. fox flr i wright peninsula on the cactern side of adelaide island. showing the area covered by bas scistamap series. sheet 1b fig 2 wright peninsula. showing features within the map area. majority of the area is open snowfield, rising from sea level to about 300111, but isolated nunataks reach an elevation of more than 400 m. the ter rain rises steeply to more than 1950 m to the west and more than 750m to the north. there are many heavily crevassed areas. the most detailed existing map of the area was compiled at 1 : 250,000 scale from hard-copy satellite imagery and is published as part of the scar antarctic digital database (bas, spri, & wcmc, 1993). a 1 : 50,000 scale topographic map was needed to support fieldwork on wright peninsula and the offshore islands, and as a travel map for safe access from rothera research station to the rest of adelaide island. data the data available for this map are from the following four sources: the map area is relatively well surveyed due to the proximity of adelaide base, an old bas sta tion at the southern end of adelaide island. the map contains eight points with both plan and height coordinates from the bat triangulation/ trilateration network. for historical reasons this survey network developed as a number of small networks local t o bases operating during the 1950s and 1960s. these small networks have since been linked together by tellurometry and the whole adjusted to fit thirteen geoceiver positions acquired in 1975/76 and 1977/78 (renner 1982; sturgeon & renner 1983). the rms residual error after this adjustment was * i 1 m (knight 1988; unpubl. rep. es2 ew 300/38, brit. antarc. surv.). gps re-occupation of old stations (perkins, 1993, unpubl. rep. ad6/2r/1992/l2, brit. antarc. surv.) and residuals from aero triangulation work show that local clusters sur veyed together, such as the points in the wright peninsula area, may have a relative accuracy of 2 5 m . small-scale aerial photographs were acquired by the institut fur angewandte g e o d b i e (ifag), frankfurt, as part of a collaborative project with bas, 10-19 february 1989. the photography was flown at an altitude of 6,000 musing a zeiss rmk camera with a super-wide-angle lens (focal length [f] = 85.5 mm), giving a nominal photo-scale of 1 : 70,000. the survey was flown with 80% endlap. the wright peninsula map area is covered by a block of 11 models (stereo-pairs) on three strips (5 + 5 + 1). using multiple data sources 319 larger-scale aerial photography was acquired in 1957 as part of the falkland islands and depen dencies aerial survey expedition (fidase), and in 1991 aerial photography covering part of the area was acquired by bas. both these sources were flown at an altitude of 3800m with wide angle lens cameras (f = 153 mm), giving a nom inal photo-scale of 1 : 25,000. part of a mosaic of landsat thematic mapper (tm) images was block adjusted by ifag in 1991/ 92 to the bat survey network using the method described in sievers et al. (1989). the images have also been corrected by ifag for the effects of surface elevation, using a coarse digital eleva tion model (dem) based on elevation data from the antarctic digital database (thomson & cooper 1993). the accuracy of the block adjust ment is quoted as k 7 5 m in x and y by sievers (pers. commun. 1992). however the scene cover ing the map area was heavily weighted in the adjustment because of the geoceiver point at rothera; therefore the geo-referencing of this scene is more accurate than the figures quoted for the whole mosaic. overlaying the survey points on the imagery showed a match to within one pixel on the tm scene (30 m). description of the problem established photogrammetric practice (using ana lytical equipment) would involve (1) formation of a block from the ifag photography, (2) den sification of the existing bat survey network control by aero-triangulation, (3) orientation of the stereo-models to this new control and (4) compilation of topographic detail and contouring by terrain-following from the orientated models. however. because of the combination of the characteristics of the terrain and the ways in which topographic data has been collected in the past, standard procedure can rarely be applied to ant arctic mapping projects. theoretically the ifag photography of the wright peninsula area should be well suited to the application of the meth odology described above. the 1 : 70,000 photo scale allows coverage of the area in only eleven stereo-models, the eight survey points in the area should provide acceptable initial control for aero triangulation of the block, and compilation of topographic detail from the high quality pho tography should be straightforward. the surveyed control points and data sources are shown in fig. 3. fig. 3 . map area showing control points (1-8) and data sources used for compilation of the map. survey points historical survey points, for technical reasons, were positioned for maximum inter-visibility whilst having safe access. no consideration was given t o future use as control points for photo grammetry and aero-triangulation. thus survey points can be difficult to identify and measure on aerial photography. point 1 was located on a snow peak in 1964, and the shape and position of the summit cannot be assumed to have remained constant. point 2 is too near the frame edge of the photographs to be included in the adjustment. point 4 was positioned on a ridge with no conspicuous features nearby and cannot be reliably identified on the pho tography. furthermore the survey schemes were designed to construct only a skeleton network. as a result, survey points are often too sparse and poorly distributed for aero-triangulation; there are no control points in the western strip, where the steep terrain prevented access by survey parties. stereo-model (b2) the stereo-model (b2) covering pinero island is almost entirely open water. difficulties with the “relative orientation” stage of photo-restitution 320 a . j . fox can be overcome by using well-distributed ice bergs present in the model area for parallax removal. however. this technique cannot be applied to link the model to the main block cover ing wright peninsula because the strips were acquired nine days apart and the icebergs have drifted appreciably. contouring of wright peninsula wright peninsula is dominated by a large open snowfield feeding the wormald ice piedmont (fig. 2 ) . whilst the photogrammetric block can be bridged across this area, using isolated, clearly identifiable crevasses as pass points, the absence of surface texture precludes accurate contouring. areas of dead ground the relationship between the super-wide-angle lens (f = 85.5 mm) used for the ifag photogra phy, the flying height (6000m) and the steep slopes and high relief has resulted in areas of dead ground due to lay-over effects on the photogra phy, especially near the frame edges. similarly, stereo-matching of the photography of the high, steep mountainous terrain covered by the western strip is difficult, even when using photography with 805% end-lap. methods data preparation an assessment was made of the extent to which standard practice could be applied to the project in the context of the constraints described above. successful aero-triangulation is dependent upon the quality, quantity and distribution of ground control points in the block. the characteristics of error propagation with different configurations of ground control are well established such that the theoretical minimum acceptable plan control (x and y ) is one point in each of the corner models. plan control in the block interior has little effect but extra control points around the perimeter of the block improve accuracy. a spacing of 1 5 20 models between perimeter control points is normal for 1 : 50,000 scale mapping projects with large numbers of models (burnside 1985). height error propagation is less favourable than that for planimetry and needs a more dense pattern of control for satisfactory block formation. in par ticular height control is required in the interior of the block. this is usually provided as bands of control across the block normal to the flight direc tion. the optimum distribution for medium-scale (1 : 50,000) topographic mapping is a spacing of six models between bands, with control points on alternate strip overlaps in each band (burnside 1985). the available photography and ground control do not meet these requirements because the dis tribution of the surveyed control points is inad equate for aero-triangulation of a block that includes the western strip of the ifag photogra phy; there are no control points in this strip. whilst the model covering pinero island (b2) contains a control point and could have been included in the block whilst maintaining its geo metric strength, this model cannot be linked to the other strips for the reasons discussed earlier in the section “description of the problem”. thus a strategy was devised t o maximise the available data and allow map compilation to proceed. aero-triangulation was restricted to adjustment of the central strip, and the western strip and model b2 were treated as independent units. centralstrip. t h e central strip (a on fig. 3) was formed from three models with 60% endlap and two models with 80% endlap; the extra endlap was found to be necessary t o overcome difficulties with stereo-viewing caused by the high relief of stokes peaks (fig. 2 ) . ground control in both plan and height was available in the end models (control points 2 and 8) with points 5 and 7 as redundant control in the interior of the block. all the models in the strip contain coastline and 15 supplementary height control points, well dis tributed about the strip, were extracted from the shoreline and included in the adjustment. tests o n the consistency of measuring to shoreline points suggested that they could be measured to an accuracy superior to the accuracy of the surveyed points and, accordingly, they were given equal weighting. the strip adjustment was there fore better controlled in height than in plan, but for medium-scale topographic mapping a slightly lower level of accuracy in plan than height is acceptable. pass points were located on rock wherever poss ible but. in the snowfield area in the centre of the using multiple data sources 321 strip. a few pass points had to be located on well defined crevasses, and the southern two models had t o be linked using several pass points on floating ice. the aero-triangulation was carried out using software implementing the “inde pendent models” method of adjustment. preliminary inspection of the photography in the stereo-plotter showed that the lay-over effect, discussed earlier in the section “description of problem”, would prevent the compilation of topo graphic detail for dead-ground areas (c and d in fig. 3). contouring would be impossible not only for the dead-ground areas on the photography but also for parts of the snowfield where there was complete absence of surface texture. the dead-ground problem was resolved by “patching in” topographic data from the fidase and bas photography. areas with an absence of surface texture were isolated for contouring using shape from-shading techniques. dead-ground area. both the fidase and bas photography sets at 1 : 25,000 scale were acquired using wide-angle lens cameras rather than the super-wide-angle lens type used for the ifag photography. the different lens characteristics, combined with the problem areas lying by chance in favourable positions within the fidase and bas photographs, eliminated the dead-ground problem experienced with the ifag photography (c and d in fig. 3). both these photo-sources have a much smaller area coverage per stereo model than the ifag photographs, and even the aero-triangulated minor control prepared for the ifag photography was inadequate. “tertiary” control points were extracted directly from the ifag stereo-models and used to supplement the existing surveyed and minor control for orien tation of the fidase and bas photography. compilation of the whole map area from the fidase and bas photographs is impractical. the block of more than 40 models required could not be successfully aero-triangulated due to prob lems in bridging the snowfield using the larger scale photography and inadequate control. fur thermore, currency of the data is important in this project t o ensure accurate mapping of the ice-rock interface and crevasse patterns, both of which change over time (significant changes can be detected in a decade); since the recent bas photography is restricted to the coastal strip, coverage of most of the area would be dependent on the outdated 1957 fidase photography. contouring in featureless areas. a shape-from shading technique was used to generate contours from the landsat tm imagery for the sections of the snowfield where surface detail was too sparse for reliable contouring as part of the dem. the method used is described in detail in cooper (1994). cooper (1994) recognised that for many topo graphic surfaces important simplifications can be made to the general scattering law for iiluminated surfaces. these simplifications have permitted the development of an efficient algorithm for extracting height information from digital satellite images which, given a known sun elevation and azimuth (from the image header) allows the gen eration of a dem. the elevation model created by this process is arbitrarily scaled in z (height) and may have a regional tilt. measured surface heights are needed to calibrate and level the elev ation model in order to derive reliable surface elevations. examination of the aerial photography and sat ellite imagery of wright peninsula, and the dis tribution of dem height-points derived from the ifag photography, showed areas where features were not being adequately sampled at the photo grammetric stage of compilation, due to inad equate surface texture. these areas were abstracted from the ifag landsat tm mosaic and cooper’s (1994) method was used to generate elevation models from the image sub-sets. the elevation models were calibrated using photo grammetrically derived height information, based on crevasses and sastrugi, available from the spot height coverage from the ifag photography. contours were interpolated from the calibrated elevation models and subsequently merged with the existing photogrammetric contours. piiiero island. model b2 covering piiiero island could not be included in the aero-triangulation of wright peninsula because it could not be linked to the other photography, and it has only one control point, which is insufficient to orientate the model as an independent unit. since the ifag satellite image mosaic has been block-adjusted to the bat survey network rather than to inde pendent ground control (e.g. gps), position information derived from the mosaic is directly compatible with the existing surveyed point (excluding the adjustment error of the mosaic). supplementary planimetric control was generated by selecting several well-distributed points on 322 a . j . fox pinero island, clearly identifiable o n both the aerial photography and the satellite imagery. a simple gis routine was created t o measure their positions from the geo-referenced imagery, add a survey point to a m a p overlay and output the coordinates as a stereo-plotter control point file. additional vertical control was easily derived from the shoreline. western strip. t h e western strip ( e o n fig. 3) was excluded from the adjustment covering the majority of wright peninsula for two reasons. firstly, there a r e n o control points in the western strip. inclusion of the uncontrolled photography would have weakened the geometry of the block, and extrapolation from the four control points in the central strip would have been unsafe. secondly, despite the use of photography with 80% end-lap, the combination of t h e extreme relief (approximately 2000 m height range within models). the flying height (6000 m ) and the cam e r a characteristics makes stereo-viewing of sub stantial areas of the strip difficult. the possibility of performing a strip-adjust ment of the western strip was considered. such an adjustment could have used the satellite image mosaic, secondary control derived from the adjusted central strip in the side-lap area, and height information from the northern and sou thern shorelines for control. however, even if the difficulties for a strip-adjustment created by the problems with stereo-viewing could have been overcome, large areas of the m a p could not have been compiled photogrammetrically. in conse quence, it was decided that the quality of the data would not justify t h e time required and the strip adjustment was not attempted. topographic detail for the area was compiled monoscopically by visual interpretation of the t m data. and digitised on screen. t h e application of simple image-enhancement techniques aided differentiation of rock outcrop and shadow on the imagery, and the high quality i f a g aerial photography allowed compilation of sub-pixel features. subjective "formlines" with a nominal interval of 2 5 0 m were fitted t o the imagery to give a cartographic impression of relief. model b i . t h e terrain covered by the north ernmost model of the western strip ( b l ) is rela tively low lying a n d acceptable stereo-viewing was possible. inclusion of this model in the main strip adjustment was rejected because it would have weakened t h e geometry of the block, but the model could b e orientated as a separate unit. t h e model area contains n o control points but has 40% overlap with the main strip. minor control from the strip adjustment available in the overlap area and supplementary height control from floating ice (given a n arbitrary height of 2 m ) was sufficient to orientate the model. t h e poor distribution of planimetric control had t o b e accepted. but overlaying the m a p detail compiled from this model o n t o the satellite image mosaic in the g i s provided a check for gross scaling errors. map compilation and data merging orientation of the stereo-models from t h e various sources described above t o the prepared control was straightforward. surface features, including coastline, rock outcrop, moraine deposits and crevasses, were easily compiled a t 1 : 50,000 scale from each of the d a t a sub-sets (central strip, patched areas, b1, b2 and the western strip e). despite treating the dead-ground and fea tureless areas separately, as described above, it was clear from examination of the photography a t the compilation stage that contouring by terrain following would still b e difficult t o achieve t o a n acceptable standard in other areas where surface detail was either intermittent o r indistinct. this more general problem was overcome by: (1) using photogrammetry t o collect a dense array of spot heights, (2) constructing a digital elevation model ( d e m ) of the m a p a r e a , and (3) inter polating contours from the d e m . all handling of geographic data after the photogrammetric data capture stage was performed using the laser-scan lites2 suite of programs. for this project the d e m approach has six advantages over t h e normal terrain-following technique: (1) t h e data compiled from the 1 :70,000 pho tography strip would have t o b e merged with other data sources for the dead-ground areas and with model b1. t h e d e m approach allows the creation of a unified height-point dataset from which a consistent set of contours can b e interp olated. this is superior to attempting to link sev eral discrete contour sub-maps generated by terrain-following from independent sets of pho tography. ( 2 ) for substantial parts of the snowfield the using multiple data sources 323 density of data points that could be acquired was barely adequate; in such areas photogrammetric heighting was dependent upon surface texture provided by sastrugi fields (wind-sculpted wave forms), indistinct crevasse snow-bridge patterns, avalanche debris, etc. with the dem method spot-heights are measured wherever such features can be identified. the dem then generates a mathematical surface based on the spot-heights, which is taken to approximate closely the true surface (provided enough heightened points have been entered); all the available information con tributes to the solution. conversely, the terrain following approach is restricted to measurement based on textural detail available only at the contour intervals. (3) height measurement with the dem method is more accurate because each spot-height is stochastically independent. in contrast, with the terrain-following technique each point is not inde pendently assessed but based on a decision about the terrain by the operator and influenced by the last few entries. where surface texture is poor, thus it is easy for heighting error to be com pounded over a series of point entries, causing the plotted contour t o drift away from the true surface. (4) height information is needed to calibrate the shape-from-shading technique and can be easily extracted from the spot-height coverage already prepared for the dem. ( 5 ) the dem produced as a by-product of this contouring technique is potentially useful for other projects such as glaciological modelling. a dem derived from contours compiled by terrain following would be of lower accuracy due to the absence of data between the contours. (6) contours at different intervals can be gen erated easily once the dem has been prepared. height-point sampling for the dem from each of the photography sub-sets was planned at dif ferent densities according to surface type, with the highest density of points in steep, complex rock areas and the lowest density of points on the low angled, smooth central snowfield. however, in practice the point density for much of the snowfield area was dictated by the poor surface texture rather than the planned sampling strategy. analysis of the height-point data using a test sample area of 500 x 500 metres shows typical point counts of 500 on steep rock, 100-150 on the well-textured, steep ice found near the coast and 0-50 on the main snowfield area. furthermore, the distribution of points on the main snowfield area is strongly linear because points could often only be collected along crevasses. the meth odology adopted for merging the separate data sets is summarised in fig. 4. all the discrete sub maps were then merged by appending the files. the “super-map” created was then stratified by feature type into coverages (layers), each cover ing the whole map area. in particular the height points were separated from the surface features. great care was taken to ensure that each feature was allocated a source label. height points were given a different graphical symbol according to source (strip adjustment, patch etc.). the data sources were ranked according to accuracy. the strip adjustment of the ifag pho tography was given the highest ranking, followed by the patched areas, then models b1 and b2, with the monoscopic satellite image interpretation at e given the least priority. the priority ranking was used to establish precedence when checking for mismatches in the overlaps between the merged data-sets. for surface features, linework from the lower ranked source was rationalised using the laser scan map editing software to match the higher ranked source. the height point coverage was overlaid on the satellite imagery for context and the consistency in overlap areas between the spot heights derived from the strip-adjustment and those from the patched areas and model b 1 exam ined in the editor. any gross mis-matches could be re-evaluated in the stereo-plotter or extra data collected t o fill in any gaps before proceeding. contours were derived using laser-scan soft ware from the raw height-points by (1) delaunay triangulation, (2) re-sampling to a regular grid, and (3) contour interpolation from the grid. a grid cell size of 1 0 m x 1 0 m was used which fil tered any very high density areas. one of the main reasons for using the dem methodology is that there is less risk of measure ment error by the photogrammetrist, as described above. however it was still probable that some spurious values had been collected in areas where the snow surface texture was marginal for photo grammetry. isolated large errors in the height points cause characteristic patterns in the contour output from the dem, such as “spikes”, “pits” and “isthmuses”, allowing easy detection of spuri ous points by overlaying the contours and height point coverages. the contours can then be iter atively refined by re-running the dem generation 324 a . j . fox surface f e a x i e b exvninc mcrgcd data and identify any m i s m c h a in linework i + edit mismatches applying 1 p r i o r i t y m h n g i i a yes i ‘ i merge contoun applying pnonty ranlung fig. 4. summary of the methodology adopted for merging the separate datasets. and contour interpolation from corrected height data. contours generated by the shape-from-shading method for the featureless areas were then inserted into the main contour coverage and the corresponding dem-derived contours deleted. in accordance with the priority ranking for the data sources. the less accurate shape-from-shading contour5 were harmonised to the photogram metrically-derived contours in the main area. finally the contours and the surface features were combined for the finished m a p . results t h e m a p resulting from the method described above (fig. 5 ) can be compared with an earlier map (fig. 6 ) compiled at 1 :250.000 scale, which was the most detailed existing line m a p of the area. detailed compilation of surface features and accurate contouring with a n interval of 50 m has been possible for the new map. on the previous m a p t h e surface features a r e heavily generalised and contouring is limited t o the depiction of sub jective ‘.form-lines”. with a nominal interval of 2 5 0 m . which give a cartographic impression of the relief. discussion strip-adjustment t h e strip-adjustment yielded a photo-coordinate standard deviation equivalent to 3.2 m o n the ground (table 1). root-mean-square (rms) coordinate errors were 2.8 m in plan and 2.5 m in height, with the largest single residual 5 m. these coordinate errors had to be accepted, but as an error of 3 m equates t o a plotting error of 0.06 mm at 1 : 50.000 scale the results are considered satis factory for this project. t h e strip adjustment was based o n four surveyed points with x, y and z using multiple data sources 325 fig. 5. part of the completed map. the contour interval is 50 m. ice-free ground is shaded. crevasses are not shown. r w ice-free ground # 1 4 . j’ i i’w s q w fig. 6 . an extract of the area covered by bas scistamap 1b from the most detailed existing map of the area. this map was compiled at 1:250,000 scale from satellite imagery in 1990. b 4 7 ion __ coordinates and a further 15 points with a z coor dinate only (derived from the shoreline). tests showed that a measurement consistency of about 2 m was achievable with the 1 : 70,000 scale pho tography and analytical instrument used. it is believed that the largest sources of error are the estimated * 5 m accuracy of th’e surveyed control points and difficulties with their identification on the photography. observing extra shoreline points as inde pendent check points was considered. however the majority of the coastline of wright peninsula is steep ice-cliffs which is unsuitable for measuring a shoreline height. the 15 points used in the adjustment were obtained from the few sections where there was a rocky foreshore. because of this restriction any extra points would have been located so close to the existing points that they would have been of limited value as a check. reserving some of the 15 points as an independent check was rejected as further depleting the already limited control available for the adjust 326 a . j . fox t a b k 1. summary of results obtained using the different data sources. rms coordinate error fig. 3 symbol x.y z x.y at map scale data source for map compilation a ? . 8 m 1 . 5 m 0 . 0 6 m m strip-adjustment of lfag photography b1 4-5m 4-5m 0 . 1 m m independent orientation to control from strip-adjustment b2 3 0 m 1 . 0 m 0 . 6 m m independent orientation to landsat tm derived control c & d 4 5 m 3-5m 0.1 mm fidase and bas photography orientated to control from ifag strip-adjustment e 3 0 m 0.6 mm geo-referenced landsat tm mosaic compilation accuracy on the map will be lower because of plotting error. ment. using off-shore icebergs to check the orien tation of the photography was also rejected because previous experience with other projects has shown that accurately measuring the sea/ice interface on floating ice is unreliable. shape-from-shading contours rms errors in fitting the elevation models gen erated by cooper’s (1994) method to photo grammetrically measured calibration points were 10-20 m. contours derived by this technique are shown as approximate on the map. cooper’s (1994) method assumes that the scat tering properties of the surface are uniform. error was observed to be greater with larger image sub sets. implying that the assumption of uniformity is invalid for this area. the snowfield is relatively lowlying (sea level to -100 m) and in a maritime environment. it is probable that there are vari ations in snow wetness within the snowfield which are likely to affect albedo; this factor is believed to be the major source of error. less significant sources of error include corruption of the reflec tance value of pixels in heavily crevassed areas, and the error component of the photogrammetric heights used in the calibration. slope is important because of the simpli fications to the general case equations made by cooper (1994). errors arising from the assump tion of negligible slope are proportional to the sine of the slope. since the snowfield areas con toured by the shape-from-shading technique typi cally had slopes of less than 2”. errors from this source can be discounted. “patched” areas and m o d e l b1 the stereo-models for the patched areas and model b1 were both orientated to control points derived from the strip-adjustment, and from direct measurement of the stereo-models in the main strip. in practice these supplementary models could be orientated to the minor control with errors of less than 2 m (which are cumulative to the errors in the strip-adjustment). such small errors are principally due t o the difficulty of ident ifying points on photographs with differing states of snow-cover and direction of illumination. the patched areas are, therefore, of lower, but similar order of accuracy to the main photogrammetric compilation and are acceptable for this project. piiiero island this model was orientated to one surveyed point in the bat network, four plan control points extracted from the geo-referenced tm image mosaic and nine shoreline heightened points. rms error in the orientation of the model was 29 m in x. 26 m in y and 1.9 m in z. the x and y values equate to a scaling error of 0.6 mm at map scale. the pixel size of the tm imagery is 30 m. the residuals from the orientation are within the nominal accuracy with which points on the images can be located and have to be accepted. western strip despite the availability of high quality aerial pho tography as an interpretation aid for compilation of sub-pixel detail, the 3 0 m resolution of the sensor constrains the accuracy of the mapping in this area. the formlines at a nominal interval of 250m are correct in shape but essentially sub jective in height and are included only to give a cartographic impression of relief. using multiple data sources 327 map compilation and data merging plotting accuracy on the map will be variable. planimetric accuracy can be expected to be close to that quoted for the strip-adjustment. heighting accuracy in ice-free or well-textured snow areas, where a dense network of spot heights could be collected, will be relatively reliable, but some degradation of accuracy is inevitable due to the approximation by the mathematical surface gen erated by the dem and the contour interpolation process. heighting accuracy will be lower where surface texture was poor or where rugged terrain has combined with the camera lens characteristics to make stereo-viewing difficult. in areas where the measured spot heights are sparse, the dem may be a less valid approximation of the true surface and the interpolated contours will, therefore, be less accurate. quantifying the quality of the height data is not possible without independent check points, but its consistency can be subjectively gauged from the complexity of the derived contours. complex contour lines across areas known to be smooth, such as the main snowfield, indicate noisy data. however, position errors of a few metres are insignificant at map scale (5 m = 0.1 mm). height accuracy is usually of more importance to the user of a topographic map, but, despite the difficulties of measuring the accuracy of the contours, it is considered acceptable for this project. conclusions using a gis framework to merge the map data derived from a variety of sources by the tech niques discussed has allowed the compilation of an effective 1 : 50,000 scale topographic map of an area previously unmapped at this scale. standard photogrammetric techniques alone would have restricted mapping to an incomplete compilation of both topographic detail and contour infor mation. by close reference to the compilation of bas scistamap l b , this paper presents a “tool-kit’’ of techniques which it is hoped may find wider application in other areas presenting similar obstacles to the compilation of large-scale maps. in particular the project shows how archive survey data and photography, which was not originally planned for large-scale mapping (and at face value seems of little use), can be enhanced by comple mentary and more up to date data sources to allow compilation of a useful map. the main unresolved problem with the method described is the difficulty of quantifying accuracy at both the initial data preparation stage and for the final map compilation due to inadequate primary survey information. normal mapping practice would be to predict the accuracy possible from the available sources, and if this did not meet the required standard, to acquire better data. however, repeat data acquisition in ant arctica needs long-term planning and the con straints of the data available have to be accepted. the philosophy for mapping remote areas has to be to produce the best map from the available data, even if the accuracy of the map is less than the ideal and difficult to quantify; a slightly flawed large-scale map is preferable to either an inac curate small-scale map or no map at all. acknowledgemena. a. p. r . cooper and j . w . thomson. british antarctic survey, provided much useful discussion and many helpful comments on the manuscript. references british antarctic survey. 1995. rothera point wright penin sula, adelaide island. bas scistamap series, sheet 1a and 1b. 1:2,000 and 1:50,00oscale maps. cambridge. british antartic survey. bas, spri. & wcmc. 1993: antarctic digital database user’s guide and reference manual. this.manua1 accompanies a cd rom. scientific committee o n antarctic research. cam bridge. 156 pp. burnside, c. d. 1985: mapping from aerial photographs. collins, london. 348 pp. cooper. a . p. r . 1994: a simple shape-from-shading algorithm applied to images of ice-covered terrain. trans. geosci. remote sensing 32 (6). 1196-1198. renner, r. g. b. 1982: an improved gravity base-station network over the antarctic peninsula. brit. antarc. suru. bull. 5 1 , 145-149. sievers, j . , grindel, a . & meier. w . 1989: digital satellite image mapping of antarctica. polarforsch. 59. 25-33. sturgeon, l. j . s . & renner. r . g. b. 1983: new doppler satellite controlled gravity stations in antarctica. brit. antarc. suru. bull. 5 9 , 9-14. thomson. j . w. & cooper, a . p. r. 1993: the scar antarctic digital topographic database. antarc. sci. 5 , 239-244. norsk yolarinstitutte bibliotek preface this number of polar research contains papers arising from the human role in reindeedcaribou systems workshop, held in rovaniemi, finland, from 10 to 14 february 1999. following on the heels of last year’s polar aspects of global change symposium proceedings issue, this set of papers is also multi-disciplinary. and it, too, grapples with questions concerning change, though extending much further into the realm of socio-cultural inquiry. as enthusiastic as we at polar research were to publish these papers, some of which depart rather significantly from our usual fare, we would like to assure our regular readers that the next issue will contain a more typical collection of articles on diverse subjects. the human role in reindeedcaribou systems workshop included some 10 keynote addresses and about 35 posters, encompassing the following themes: hunting systems; reindeer herding; rangeland habitat protection; minimizing industrial development conflicts; effects of global change; and protecting indigenous cultures. the articles herein are those that successfully passed through the peer review and revision process, as overseen by an editorial team made up of the journal’s editor and bruce forbes, gary kofinas, david klein and igor krupnik. this set of papers is introduced by kofinas et al. with an account of the interdisciplinary research planning process undertaken in rovaniemi and the research plan for human-rangifer studies that comes from the workshop. the articles that follow are organized by subject, moving from a focus on reindeer herding systems in transition to reindeedcaribou interactions, climate change, future research and the challenges of cultural continuity. baskin, krupnik, gray and klokov put russian reindeer herding into a historical perspective, with baskin touching on the little appreciated role of hunting systems of that region. all reflect on the current “crisis,” with krupnik speaking directly to research needs at this critical time. focusing on north america, dau addresses the challenges of reindeer herding and caribou management of alaska’s seward peninsula, where the interaction of wild and domestic herds has resulted in conflicts and economic loss. focusing on human disturbance and the effects of industrial development and infrastructure, aastrup, wolf et al., reimers et al. and klein offer important contributions by reviewing available literature, describing current studies, and raising outstanding research questions. lee’s paper moves us towards the global question of climate changes, by examining its specific regional effects in muotkatunturi, finland. kryazhimskii & danilov remind us of the often neglected, yet critical issue of system complexity. the papers by danell and russell et al., like those by reimers et al., krupnik, klein and turi, suggest research priorities, with danell and russell et al. offering novel approaches for achieving them. turi took one of the workshop’s primary tasks to heart by providing an indigenous perspective on the subject, and golovnev has been given the final word in this issue. he offers a sobering insight into another “crisis,” reporting first-hand on 2000: polar research i 9 ( 1 ) , 1-2 1 the struggle for survival of an indigenous community caught up in the development of petroleum resources in russia’s nenets autonomous okrug. the international arctic science committee (iasc) is thanked for its ongoing support of the human role in reindeedcaribou systems project, including the funding which is being applied to publication costs. the john d. and catherine t. macarthur foundation, the trust for mutual understanding, us national science foundation and many other organizations also provided significant support. for a complete list of workshop sponsors, see table 3 in kofinas et al., this issue. the efforts of workshop co-leaders, gail osherenko and david klein, as well as the other members of the steering committee (see table 2, kofinas et al.) must also be acknowledged. special thanks are given to deborah robinson for her superb work as workshop coordinator, and to raija kivilahti and ulla heiskari for seeing that the workshop ran smoothly in rovaniemi. to obtain copies of this issue, contact the institute of arctic studies, dartmouth college, 6412 fairchild, hanover, nh03755, usa., artic@dartmouth.edu. copies can also be purchased from the norwegian polar institute; inquire at sales@npolar.no. helle v. goldman, editor-in-chief bruce forbes, special co-editor gary kofinas, special co-editor map offering a very general overview of the circumpolar distribution of wild rangifer (horizontal hatching) and reindeer husbandry (vertical hatching). the former excludes small local pockets of reindeer and the latter is rather loosely defined. (w. k. dallmann drafted the eurasian distribution, drawing from: atlas sssr, 1984, moscow; a. a. nazarov & 0. n. shubnikova, 1994. “the geography of wild reindeer in northern russia,” polar geography and geology !8(3), pp. 231-244; various sources listed in dallmann, 1997, indigenous peoples of the northern part of the russian federation and their environment, insrop working paper 90-1997; and s . e. belikov, a. n. boltunov & t. p. belikova, pers. comm., 1997. g. kofinas and d. russell contributed to the north american section. thanks also to s. kaitaldcaff and l. baskin.) 2 p r e f a c e the barents sea ice sheet a sedimentological discussion a . elverhbi and a. solheim 0 e l v e r h ~ i , a. & solheim, a. 1983: the barents sea ice sheeta sedimentological discussion. polar research i n . s . , 2>42. oslo. sediment sampling and shallow seismic profiling in the western and northern barents sea show that the bedrock in regions with less than 300 m water depth is unconformably overlain by only a thin veneer (< 10 m) of sediments. bedrock exposures are probably common in these areas. the sediments consist of a holocene top unit, 0.1-1.5 m in thickness, grading into late weichselian glaciomarine sediments. based on average sedimentation rates (14c-dating) of the holocene sediments, the transition between the two units is estimated to 10,00~12,000 b . p . the glaciomarine sediments are commonly 1-3 m in thickness and underlain by stiff pebbly mud, interpreted as till and/or glaciomarine sediments overrun by a glacier. i n regions where the water depth is over 300 m the sediment thickness increases, exceeding 500 m near the shelf edge at the mouth of bj0rnbyrenna. in bjbrn0yrenna itself the uppermost 15-20m seem to consist of soft glaciomarine sediments underlain by a well-defined reflector, probably the surface of the stiff pebbly mud. local sediment accumulations in the form of moraine ridges and extensive glaciomarine deposits (20-60m in thickness) are found at 250-300m water depth, mainly in association with submarine valleys. topographic highs, probably moraine ridges, are also present at the shelf edge. based on the submarine morphology and sediment distribution, an ice sheet is believed to have extended to the shelf edge at least once during the pleistocene. spitsbergenbanken and the northern barents sea have also probably been covered by an ice sheet in the late weichselian. lack of suitable organic material in the glacigenic deposits has prevented precise dating. based on the regional geology of eastern svalbard, a correlation of this younger stage with the late weichselian is indicated. anders eluerhgi andanders solheim, norsk polarinstitun, rolfstangueien 12,1330 oslo lufthaun, norwav. june 1982 (revised november 1982). introduction the question of a barents sea ice sheet represents an outstanding problem in the reconstruction of former glaciations on the northern hemisphere. with regard to the late weichselian the views currently held on the glacial history of the region can be summarized: (1) total glaciation of the barents sea (gross wald 1980; andersen 1981; hughesetal. 1981, maximum model). extensive glaciation of the barents sea is also suggested by hoppe (1970) and kvasov (1978). (2) glaciation of the shallower regions with b jqrn0yrenna and storfjordrenna as calving bays (matisov 1980). (3) no glaciation significantly beyond the coasts of svalbard (baranowski 1977; boulton 1979a, b). essential elements in grosswald’s (1980) concept of a total glaciation are: (1) a continuation of the ‘egga moraines’ (end moraines on the norwegian shelf (andersen 1968)). northwards along the shelf edge west of the barents sea (koteniov et a/. 1976). (2) presence of stiff pebbly mud in large parts of the barents sea implying till deposits (dieb ner 1968). (3) moraine ridges in northern russia formed from a glacial advance from the northwest at the end of the late weichselian or in the early holocene (grosswald et nl. 1974). matisov (1980 and numerous earlier publications) based his conclusion on a geomorphological study of the sea floor. a main line of argument was ridge complexes near the mouths of submarine valleys, especially those extending out from spitsbergenbanken. the main arguments for boulton’s hypothesis of a non-glaciated barents sea are: (1) the probable presence of extensive glacio (2) earlier observations of till (e.g. diebner 1968) (3) little apparent evidence of glacial erosion. marine sediments in the barents sea. are doubtful. 23 24 a . e i u e r h ~ i & a . solheim boulton (1979b) argues that t h e main barents sea basin has not been glaciated at all during the pleistocene essentials for the discussion of a late wei chselian barents sea ice sheet have in general been: (1) the presence of undated high beaches on kong karls land. ( 2 ) the apparent straight-line emergence curves for kong karls land and h o p e n published by h o p p e (1970). (3) glacial striae on h o p e n ( h o p p e er a l . 1969). these, however, have been reinterpreted as non-glacial (hoppe 1981). boulton (1979a) suggested that the high beaches were probab\y very old and that the anomalous pattern of the uplift curves o n h o p e n and kong karls land were the result of one. or a cornbi nation of the following three possibilities: (1) uplift of t h e islands may have been influenced by a substantial glacier regeneration on sval bard during the late holocene ('little ice age'). (2) uplift could have been restrained during the holocene by a rapid eustatic sea level rise. (3) uplift may have been influenced by a tectonic component. a tectonic uplift has also been suggested by semevsky (1967). recent years' detailed glacial geology studies o n kong karls land have. however. revealed an early holocene age for the high beaches 10011-1 above sea level (salvigsen 1981). furthermore, an asymptotic or normal emergence curve has been found. similar emergence curves have also been published for nordaustlandet (salvigsen 1978) and edgebya and b a r e n t s ~ y a (knape 1971), which combined with the observations on kong karls land strongly suggest that a late weichselian ice sheet also covered much of the northern barents sea (salvigsen 1981). in this paper new information on the stratig raphy and facies of the quaternary sediments in the barents sea is related to the question of glaciations. t h e investigations have been conducted in the south-western ( b j ~ r n o y r e n n a ) , northwestern (spitsbergenbanken). and the northern ( w of 35"e) barents sea, and only these areas have been taken into consideration. sediment distribution and thickness t h e principal findings o n sediment type, distri bution and composition can be summarized as follows (figs. 3. 4. & 5 ) : 1) stiff pebbly mud (till and/or glaciomarine sediments overrun by a glacier) covered by soft mud with pebbles (glaciomarine depos its). in areas with < 3 0 0 m water depth, the thicknesses of the two units a r e in general <15 m and <3 rn, respectively. 2 ) large sediment accumulations are present in the western part of the major troughs (bjsrnoyrenna and storfjordrenna) and exceed 500 rn in thickness near the shelf edge, decreasing towards the central and inner parts of the troughs. (3) in regions with >300 m water depth. the gla ciomarine sediments increase in thickness, 15-20 m , and a r e overlain by fine-grained holocene mud. rich in foraminifera and organic debris. thickness of the holocene mud is commonly <1.5 m . t h e fine-grained mud is also localized in shallower areas, especially in smaller depressions. the stiff pebbly mud is probably also present under neath the glaciomarine sediments in these areas. (4) transverse moraine ridges are present in the troughs radiating o u t from spitsbergenban ken. ridges a r e also parallel to the shelf break in b j o r n ~ y r e n n a and west of spits bergen ban ken. (5) t h e boundary between the bedrock and the sediments is seen as a well-defined angular unconformity . (6) o n spitsbergenbanken the glacial sediments have been reworked by currents and mixed with holocene bioclastics. a gravelly lag is also common in shallower ( < l o o m ) parts in the northern and central barents sea. distribution of the glaciomarine deposits t h e soft sediments sampled from b j ~ r n ~ y r e n n a / storfjordrenna, and the central and northern barents s e a a r e characterized by a n olive-grey unit, 0.1-1.5 m thick, underlain by blue-grey sedi ments (fig. 6 a , b). a similar sequence is found on the northern slope of spitsbergenbanken, while o n t h e south ern slope stiff pebbly mud is frequently exposed the barents sea ice sheet .. . 0 . 25 72" 70" i'o" 4 i a 20" 35" fig. 1. sediment samples obtained during geological surveys i n the barents sea by the norwegian polar research institute and the norwegian petroleum directorate. i n general a 3 m long gravity corer is used, except for spitsbergenbanken (<75-100 m water depth) where the samples are obtained by grab. also location map for cores shown in fig. 6. 26 a . elrlerhgi & a . solheim fig. 2. shallow seismic profiles in the western and northern barent5 sea obtained by the norwegian petroleum directorate and the norwegian polar research institute. the numbers refer to seismic profiles presented 1 5 20' 2 5 ' 3r' 0 n n o r w a y sparker 3 5 hh2 sounding 80. 78' the bartirits sea ice sheet 10. 16. $0. 2s. *.$ ;c 20' ;b' .l %.&/ c-, western barents se 21 fig. 3. sediment distribution map of the northern and western barents sea 28 a . elverhli & a . solheim water depth stiff pebbly mud ( t i l l ) fig. j generalized block diagram illustrating the sediment distribution in the northern and central barents sea. soft blue-grey mud f i n e grained o l i v e grey mud holocene s t i f f pebbly hud ( t i l l ) fis. 5 fig. 5 . generalized block diagram illustrating the sediment distribution on the slope south of spitsbergenbanken and northern part of bjarneyrenna. the barents sea ice sheet 29 b a 0.: 1.0 1.5 i b e n t h i i n i c f o r a m i n i f e r a i i 1 s e l e l t e u s f l c i e s i 5 . . . . . . . . . . . . ". fig. 6 . characteristic lithology and foraminifera1 fauna in sediments from 0 a . bjbr~myrenna (from elverhei & bomstad 1980). 0 b . centraynorthern barents sea. colour code refers t o munsell soil color charts (5 y 4/2: olive grey, 5 y 4/1: dark grey). for location, see fig. 1. at the seabed down to 350m water depth unit is rich in organic debris and foraminifera. (bjarlykke et al. 1978). the blue-grey unit, however, has a higher content in the northern and central parts of the barents of pebbles and a very low content of foraminifera, sea both units are typical glaciomarine deposits, all with affinities to cold water (fig. 6b), showing soft mud with ice-rafted pebbles. the olive-grey a more glacially influenced depositional environ 30 a . elverhsi & a . solheirn sawple nr 8 0 5 2 4 3 5 7 6 3 8 0 1 3 7 8 0 1 3 7 8 0 1 2 0 8 0 1 0 5 8 0 1 0 6 9 2 8 1 9 3 9 8 1 35 6 8 9 2 6 3 l ment than the overlying olive-grey deposits. in b j ~ r n ~ y r e n n a and storfjordrenna the olive-grey unit very seldom contains pebbles, but the under lying unit is similar to that found in northern and central regions. in some cores from the shallower areas (< 200m water d e p t h ) in the central and northern regions, a thin lag of pebbles and shell fragments indicates a minor erosional episode a t the tran sition from the olive-grey unit to the underlymg blue-grey one. “c-dating. core 137. table 1. indicates a mid-holocene age for this event. how ever, generally, and for all the deeper parts, the boundaries a r e transitional with regard t o colour, texture, as well ae foraminifera assemblage (fig. 6a. b), indicating a continuous sedimentary sequence. “c-datings of molluscs in the middle and lower parts of the olive-grey unit give an early/mid holocene age (table 1). all datings from cores have been obtained on whole bivalves of astarte sp. in life position. these molluscs live just below table 1. “c-datinga of sediments from the western and northern barents sea. datings of surface samples from spitsbergenbanken are also included (data from bjerlykke ef ul. 1978). 27 5 1 4 5 300 1 2 5 1 2 5 300 1 4 9 1 6 5 5 0 58 30 158 58 60 35 5 6 3 5 uterial b l l u s c 4 s t a r t e jp . * o l l u s c !4ya t r u n c a t a n 0 1 1 u 0 c s a x i c a v a b a r n a c l e ! ‘c-age vears bp 8 . 0 6 0 3 1 0 4.210 t 330 7 . 2 3 0 3 4 0 4.290 t 1 6 0 6 . 6 7 0 t 1 2 0 5 . 7 8 0 t 2 7 0 8 . 5 8 0 +_ 2 9 0 1 . 7 5 0 2 2 0 0 4 . 3 7 0 t 1 3 0 2.390 1 1 0 8 . 7 3 0 1 1 0 9 . 1 4 0 t 1 0 0 280 : 1 1 0 2 1 2 0 9 9 0 1 1 0 2 . 3 4 0 2.250 t 1 2 0 6 4 0 t 7 0 depth i n core ( m i 0 . 2 5 0 . 1 0 0 . 1 9 0.35 0 . 5 0 0 . 1 0 0.26 0.30 s u r f a c e 3.1 3.4 2 . 6 8 . 2 ‘ i . 5 1.7 2.3 3.9 lab. ref number t 3830 t 3 3 9 6 t 3 3 3 3 t 3 8 3 2 t 3 8 3 4 t 4 1 7 1 t 3 8 3 1 t 3 8 3 3 t 1798 t 1 7 9 9 t 1687 t 2 8 7 1 t 1808 t 180c t 1797 t 1 8 0 1 t 1 6 8 f n o r d a u s t w ? i p i t s nrgen land m r-. i , n p, 9, -.* ..i ’2. the barents sea ice sheet 31 the sediment surface and are too big to have been recycled because of bioturbation. until now there has been no success in obtain ing datable material from the blue-grey unit, but the transition to the overlying holocene unit can tentatively be dated t o the end of the late wei chselain (10,000-12,000 b.p.): (1) there is apparently no sign of a hiatus between the olive-grey and blue-grey deposits. (2) an early holocene to mid-holocene age was obtained for the lower part of the olive-grey deposits. (3) in the few shallower areas with sign of erosion at the transition, the erosional episode is of early/mid-holocene age. (4) a marked lithostratigraphic boundary between glaciornarine and younger non-gla cigenic sediments is dated to 10,000 b.p. in the area just south of the barents sea (vorren et al. 1978). a late weichselian age for at least the uppermost part of the blue-grey sediment in bj0rnoyrenna is also seen from data published by grosswald (1972). in a ‘core taken at a sea depth of 370 m between bear island and the northern tip of nor way’, 12,385 +280 b.p. (st.-3341) was obtained on a shell in a depth interval of 37-52cm. this layer is grey i n colour, containing pebbles and a foraminiferal assemblage similar to that found in our blue-grey unit. the lithology of the blue-grey glaciomarine sediments is homogeneous with no sign of erosional episodes. the recovered foraminiferal fauna is also uniform, consisting of only extremely cold water species, suggesting that the blue-grey deposits form a single depositional unit. how ever, it should be noted that a complete section through the blue-grey sediments into the under lying stiff pebbly mud has only been obtained in a limited number of cores, confined to the south ern slope off spitsbergenbanken and from the northern barents sea. no final conclusion can thus be drawn on whether the blue-grey glacio y s e c . 0.3 a c s e c . r 5 k m two-uay t r a v e l time i n s sec . s e c . 0 . 4 5 0.55 b 0.65 0 . 7 5 t w o y d y t r a v e l t,me * fig. 7. el a . characteristic 3.5 khz echo sounding profile from the northern barents sea, showing 1-3 m of soft sediments above a well defined reflector-tilvbedrock. 0 b . 3.5 khz echo sounding profile from bjemmyrenna, southeast of bjmnaya. the lower boundary of the glaciomarine sediments is shown by the arrows. for location of the profiles, see fig. 2. 32 a. e l u e r h ~ i & a. solheim marine sediments have been deposited continu ously or include periods of erosion/non deposition. the thickness of the glaciomarine (blue-grey) sediments has been obtained from sediment cor ing, and by 3.5 khz echo sounder recores (figs. 2 , 7). a 3.5 khz echo sounding profile south of b j ~ r n ~ y a shows the blue-grey glaciomarine deposits apparently increasing to 15-20 m into b j ~ m ~ y r e n n a (fig. 7b). these sediments have earlier been interpreted as glacial till or moraine deposits from data mainly based on 3.5 khz echo sounding (damuth 1978). on the lower part of the slope from spitsbergenbanken, the thickness seems to be < 2 m, as found by sediment coring. in storfjordrenna and also in a trough northeast of kong karls land, thick ( 4 0 4 0 m ) deposits have been recorded on sparker profiles (fig. 8a, b). based on their acoustically transparent char acter and lack of internal reflectors, these deposits probably consist of soft, homogeneous sediments. there are also 3.5 khz echo sounding profiles across the deposit northeast of kong karls land. sediment coring, supplemented with i4c-dating (core 7 6 3 , 80-120, table l), revealed the blue grey glaciomarine sediments below half a metre of holocene deposits. because of their homo geneous composition, the blue-grey glaciomarine sediments sampled near the seabed almost cer tainly make up the entire accumulations. in a depression south of kong karls land, and also at the innermost part of b j ~ r n ~ y r e n n a , similarly acoustically transparent sediments are found below the holocene sediments. these deposits are also interpreted as consisting of the blue-grey glaciomarine sediments w e s l s e c o n d c 5 r 0 7 1 08 l 0 9 l 0 6 a 04 0 5 06 0 7 08 acoustlcally transparent e a s t glaciomarlne sedlments 04 05 06 07 08 0 5 i0 krn l i acoustically transparent glaciomarine sediments second unconformlty consolidated rocks 'y 0 1 2 3 4 5 k m f i g . 8 . 2 a . sparker profile from the outer part of storfjordrenna. the extension of acoustically transparent deposits is confined to the east by a bedrock sill. 0 b . sparker profile across a trough northeast of kong karls land. the acoustically transparent deposits are found at water depths >300m (from kristoffersen e i a l . i n press). for location of the profiles, see fig2. the barents sea ice sheet 33 80" 78" 76' t 74' ; 72' ~. '. i \ fig. 9. map showing localities where stiff pebbly mud has been sampled and investigated. shear strength and water content determinations from the different lithologies are listed. grain-size analyses for the samples are shown. *: analysed samples. analyses: norwegian geotechnical institute. the stiff pebbly mud texture and distribution in regions shallower than 300 m, the stiff pebbly mud was sampled at ten localities during the surveys in 1978 and 1980 (fig. 9). geotechnical tests made on three of the samples show shear strength values in the range of 4-6t/m2 (40 60 kn/m2), which is an order of magnitude higher than that found for normally consolidated surface sediments, e.g. the sample from b j e r n ~ y r e n n a (fig. 9). because of the stiffness only 20-30cm of this type of deposit was obtained by gravity coring. larger samples were collected with the 1 m3 grab. lumps of the same material were also recovered with a pipe dredge. these sediments seem t o be very thin in regions shallower than 300 m (fig. 10). from the sparker records the sediment thickness above bedrock is found in general t o be < 1 5 m (because of the pulse width, no resolution is obtained in the first 10-15 m below sea bottom). supported with data from the 3.5 khz echo sounding and the sediment coring, the sediment thickness is estimated to be < 5 m . in some areas the bedrock is exposed, exemplified with a bottom photograph (fig. 11). there has been no sampling through the stiff pebbly mud into the bedrock. 34 a. e l u e r h ~ i & a. solheim in areas deeper than 3 0 0 m there is a general thickening of sediments above bedrock (fig. 12a). based o n the 3.5 khz echo sounding and sediment coring. the upper 15-20m of the deposit in b j o r n ~ y r e n n a probably consists of soft sediments. the reflector seen on the 3.5 khz pro file (fig. 7 ) is thinning out t o only 1-2 m on the lower part of the slope from spitsbergenbanken. sediment coring close t o the profile showed exposure of the stiff pebbly mud, t o which the reflector is correlated. consequently the stiff peb bly mud seems to extend into b j o r n ~ y r e n n a . deposirional mechanism in addition t o a basal till origin. stiff pebbly szdi ments may form from ice-rafted deposits com pacted by various factors ( a mud flow origin is excluded): ( a ) sediment loading. removal of overlying sediments d u e to gravity flow. however. is unlikely because of the low gradient. alterna tively. submarine erosion of glaciornarine sedi ments would have developed lag deposits, which have not been found. (b) action ofpermafrost (williams 1967). -sub sea permafrost has to form out from land (or s beneath a cold glacier). a late weichselian drop in sea level of 100-130m would cause subaerial exposure of parts of the barents sea. t h e stiff pebbly m u d , however, is sampled at water depths well below and away from what could have been exposed during that regression. assuming tectonic stability, the stiff pebbly mud is further sampled below water depths that can have been subaerially exposed during former, larger pleis tocene regressions. according t o the above, the stiff pebbly mud is most likely a till and/or glaciomarine deposits overrun by a grounded ice. a t water depths shal lower than 300 m , i.e. spitsbergenbanken and the northern barents sea with only a thin sediment cover and frequent exposure of the bedrock, the stiff pebbly mud is tentatively classified as basal till. i n areas deeper than 3 0 0 4 0 0 m . with con siderable thickness of sediments above the bed rock, the stiff pebbly m u d may. however, have been of glaciomarine origin. according t o drei manis (1978), these sediments may be classified as deformation t i l l . ice marginal features ridge complexes and areas of relative topograph ical highs that a r e not caused by bedrock have been observed in the following regions: n second r 0 . 3 f ~ . 3 1 m o r a i n e ridge 3 1 2 3 4 5 k r n fig. 10. sparker profiles from the northern barents sea illustrating: el a . the general existence of only a thin ( 1 1 5 m) cover of sediments above the bedrock. forming a well-defined angular unconformity with the sea floor. 0 b. an up to 5 0 m thick accumulation of glacigenic sediments on storbanken at 1501x1 uater depth. the accumulation is probably a moraine (from kristoffersen er al. in press) for location of the profiles. see fig. 2 . the barents sea ice sheet 35 fig. 11. bottom photograph from the northern barents sea. bedrock exposed in the left part of the photograph. 80” 24’ n , 29” 55’ e, 240 metres water depth (published with the permission of c . craine.) (1) in the mouth of troughs radiating from spits bergenbanken (fig. 12b). (2) near the shelf edge at the mouth of bj0rn0yrenna and storfjordrenna (fig. 8a and 13). (3) on the upper slope/shelf edge west of spits bergenbanken (fig. 12c). (4) on storbanken, central barents sea (fig. lob). (1) both leirdjupet (se of b j ~ r n ~ y a ) and kveit hola (nw of bj0rnqya) form overdeepened troughs where the outer high is caused by sedi ment accumulation. in adjacent areas, only a sparse cover of sediment is present (fig. 3). in leirdjupet the ridge has an asymmetric pat tern, with the steepest slope facing southwards (fig. 12b). the surface, especially the north facing part, is hummocky. stiff pebbly mud was recovered from the surface. with the exception of a minor reflector in the lower part, no other evidence of internal structures has been obtained so far. from the geometry, the location in front of a valley, and the sediment distribution in adjacent areas, this feature appears to be depos ited by a glacier flowing down leirdjupet. the thickness (approx. 100m) and ‘width’ (approx. 10 km) of the ridge in leirdjupet are much larger than commonly found for end moraines on land. on the northern norwegian shelf, features interpreted as end moraines are also very wide, 5-15 km (rokoengen et a f . 1979). vorren & elvsborg (1979) suggest that the broad appearance of these shelf deposits reflects a moraine complex rather than a single end moraine. it should be noted that the shelf moraines were deposited by ice influenced by buoyancy. the erosional power of the ice is then strongly reduced in its frontal areas and depo sition is likely to start far back from the ice front. (2) in the central parts of the mouth of bjorn0yrenna there is a 50 m high sediment accumulation (fig. 13). the ridge feature, sup ported with the truncated reflectors, suggests a glacial origin, probably an end moraine. sparker profiles north of 73”n do not show any northward continuation of the high. grosswald (1980) and andersen (1981) suggest a continuation of the ‘egga moraine’ to the north. available bathy metric data from the area, however, are very limited and do not form a reliable data base for detailed contouring. our seismic profiles also stop southward at 72”n. at the present stage, a con 36 a . elverhli & a . solheim p n s fig. 12. 0 a. sparker profile from bjbrnqyrenna south of bjbrnbya, illustrating (1) increasing sediment thickness into bjernbyrenna. and (2) the well-defined angular unconformity between the bedrock and sediments. 0 b. sparker profile from leirdjupet showing an up to 150 m thick accumulation of glacigenic deposits at 300 m water depth. the accumulation is probably deposited in the frontal zone of a southward moving ice sheet. a minor moraine ridge is seen at approximately 200 m water depth (above). (from e l v e r h ~ i & kristoffersen 1977. ) 0 c. sparker profile across probable moraine ridges west of spitsbergenbanken. for location of the profiles, see fig. 2. b n icco”d 0.3 0 4 0 1 2 k m s bjornoy renna 0 . 4 0.5 0.6 0 1 2 k m nection between the observed high and the ‘egga records shows truncated reflectors, indicating moraine’ remains an open question. episodes where glacial advance and erosion were the mouth of storfjordrenna (fig. 8a) also followed by deposition as the ice sheet retreated, forms a topographical high relative to the inner instead of a continuous build-up and pro parts. the reflection pattern on the sparker gradation. the barents sea ice sheet 37 2 a sec. 2 two-way i b sec 0 . 9 w e bj0rnqyrenna 10 km ikj sparker profile fig. 13. interpreted sparker profile from the mouth of bjbrn0yrenna. note that the outer high is caused by sediment accumulated above reflector 2. for location, see fig. 2. (3) on the slope west of spitsbergenbanken, the bottom is hummocky with a relative scale of 25-50 m (fig. 12c) forming ridges oriented almost parallel to spitsbergenbanken. based on their geometry and orientation, these features are interpreted as end moraines deposited by an ice sheet advancing from spitsbergenbanken. (4) the morphology of the ridge strongly suggests a glacial origin, most likely an end moraine. in addition to these features, local accumulations are found (1) at the innermost part of storfjordrenna, (2) at 150-200m water depth in the troughs extending radially out from spitsbergen banken (fig. 12b), (3) on the southern slope off spitsbergenbanken, and (4) at storbanken and sentralbanken. sediment sampling in the areas of 2, 3, and 4 showed stiff pebbly mud, indicating till (and/or glaciomarine deposits overrun by a glacier). erosional features the sediments are everywhere commonly uncom formably overlying the bedrock (e.g. figs. 8b and 12a). of special importance are the overdeepened regions in central parts of the barents sea (fig. 14). as these features are formed by excavation into the bedrock (fig. 3), they are most likely due to glacial erosion. discussion the sediment distribution and stratigraphy (till overlain by glaciomarine sediments grading into postglacial deposits) clearly demonstrate that the barents sea has been covered by grounded ice 38 a . eluerhoi & a . sotheirn 81' 80 7 a 7f 74 7: 71 fig. 1 4 . bathymetric map showing features related to former ice margins in the western and northern barents sea the barents sea ice sheet 39 at least once. overdeepened regions south of kong karls land further indicate considerable glacial erosion in the northern barents sea. the depositional chronology cannot be established yet because of lack of datable material and inade quate knowledge on the stratigraphy of the gla ciomarine deposits. at this stage only a prelimi nary discussion may be attempted on the extent and age of barents sea glaciations. sediment distribution in relation to glaciations the extension of an ice sheet can be reconstructed from the distribution of (1) ice marginal features such as moraine ridges, and (2) areas covered by till or glacially compacted and reworked deposits. in a marine environment the distribution and thickness of glaciomarine deposits have to be included. as a possible reference for the ice sheets in the northern barents sea, at least during their retreat, observations from austfonna at nordaustlandet may be applied. this is an ice cap, 100 x 50 km, terminating in the sea along half its circumfer ence. considerable parts of the ice cap are believed to be below pressure melting point, while central parts may be at pressure melting point (schytt 1969). sediment loaded meltwater dis charge into the sea seems to confirm the existence of areas at pressure melting point beneath the ice cap. preliminary studies of the sedimentation out side the ice cap (pfirman, pers. comm. 1981; solheim & elverhsi 1982) show that the major part of both the suspended matter and the ice rafted material is deposited relatively close (within 10 to 15 km) to the ice front. with ref erence to these results, thick glaciomarine sedi ments with well-defined limits should be regarded as ice marginal features. the barents sea ice sheets were grounded below sea level, i.e. marine ice sheets. the sta bility and extension of such ice sheets are to a large extent controlled by the sea level (e.g. tho mas 1979). a marine ice sheet covering an area of low relief like the barents sea is thus likely to extend down to a common water depth over large regions. this, in turn, makes it possible to recon struct the margins of such ice sheets into areas lacking well-defined marginal features. ice marginal features are situated around spits bergenbanken at approximately 250-300 m water depth (fig. 14). from the fact that these features are observed at the same water depth, we propose that they define the outline of an ice sheet cover ing spitsbergenbanken. in the northern and central barents sea, ice marginal features are found at somewhat shal lower water depth, except for the glaciomarine deposit at 300 m water depth northeast of kong karls land (fig. 14). however, on the western slope off sentralbanken and in the inner part of b j ~ r n ~ y r e n n a at approximately 300 m water depth, there is a thickening of both the glacio marine and its underlying deposits. based on this change in sediment thickness and the glacio marine accumulations in the northern barents sea, we propose a continuous ice sheet covering the central and northern barents sea in the late weichselian. furthermore, we also propose that it was connected with the ice sheet on spitsber genbanken. to the north a coalescence of the ice on nordaustlandet/stor@ya and kvitsya is pro posed. due to findings of till on the shelf north of these islands we further propose that the ice extended further, north, confined to a water depth corresponding to a present water depth of 250 to 300 m. the extension to the northeast is defined by the franz-victoriarenna and the glaciomarine accumulation in its inner part (fig. 14). ice marginal features, somewhat less extensive than the previous ones, are found at about 15& 200 m water depth around spitsbergenbanken, in the inner parts of storfjordrenna and bj~rnqyrenna and on storbanken (fig. 14). sim ilarly, as for the marginal features and change in sediment thickness at 250 to 300 m water depth, we relate these latter features to an ice sheet somewhat smaller in extent than the former one (fig. 14). we also propose a similar, smaller ice sheet in the northernmost barents sea in the late weichselian. a more extensive and older ice sheet is, however, witnessed by findings of till (or gla ciomarine sediments overrun by a glacier) in bjsrnsyrenna and a moraine ridge at the mouth of the trough. as illustrated in fig. 14, this exten sive ice cover is believed to have reached to the shelf edge in the west. possible age of the barents sea glaciations pre-late weichselian. on svalbard an early weichselian glaciation seems to have been of a larger extent than the late weichselian (salvigsen & nydall981). such an ice may also have covered considerable parts of the barents sea. 40 a . elverhqi & a . solheim late weichselian. the northern extent of the scandinavian ice sheet is still a subject of contro versy. andersen (1968 and 1981) tentatively placed the maximum limit on the outer continen tal shelf, defined by the ‘egga moraines’. based on sediment coring and shallow seismic reflection, rokoengen et al. (1979) also suggested a glacial extension to the outer continental shelf. vorren et al. (1978) demonstrated that the shelf outside troms was deglaciated 13,000-14,000 b.p. until now the detailed stratigraphical investigations have been concentrated in the nearshore areas, while information from the outer shelf off north ern norway is limited. available data d o not provide an adequate basis to prove or disprove the existence of a grounded glacier on the outer shelf with a possible extension into bjornoyrenna. on svalbard, hoppe (1970) suggested a large continuous ice sheet covering svalbard with an extension into the northern and northwestern barents sea. investigations by salvigsen (1977) and salvigsen 8i nydal (1981), however, have shown the existence of more local and limited glaciations of the western part of spitsbergen, while salvigsen (1981) suggested that a continu ous ice sheet covered eastern svalbard, including kong karls land. recent investigations on stortiya, a small island just east of nordaustlandet (fig. l ) , show an emergence curve similar to those found elsewhere in eastern svalbard (haggblom 1982), indicating an expanded late weichselian ice sheet also in that part of the northern barents sea. concerning hopen, the existence of a late weichselian ice sheet in the area has been disputed (e.g. boulton 1979a). it should be noted, however, that only two levels older than 4.000 years b.p. have been dated so far. additionally, it seems unreasonable that the displacement on hopen should have been caused by tectonic movements, in contrast to the rest of eastern svalbard. since the whole area is on the same basement platform. it seems more likely that the displacement on hopen is also due to glacial unloading, indicating that hopen and its adjacent areas were covered by a late wei chselian ice sheet as proposed by hoppe (1970). bjtirnoya. the small island on the western flank of spitsbergenbanken, was deglaciated 11 .so0 b.p. according to gytje dates (hyvarinen 1972). lack of ‘recent’ glacial features led boulton (1979a) to suggest a non-glaciated island. accord ing to salvigsen and nydal(1981), b j ~ r n 0 y a may have escaped glaciation during the late wei chselian in common with areas in western spits bergen. an ice-free bjornoya does not, therefore, necessarily contradict the concept of an ice sheet further east o n spitsbergen. alternatively, as pro posed by hoppe (1970), bjorntiya may have been covered by only a thin ice sheet due to its position very close t o the shelf edge. the general degla ciation may further have been followed by local ice cap formation, partly or completely destroying older traces of glacial movements. from the above regional geological consider ations. i t seems likely that the northern barents sea and also spitsbergenbanken seem to have been covered by grounded ice which in tkrn is compatible with the sediment distribution. from the sediment distribution it cannot, however, be concluded whether this ice sheet extended to the shelf edge, i.e. a total glaciation as proposed by grosswald (1980) and hughes et al. (1981) (max imum model), or was confined to the spitsber genbanken and the central and northern barents sea. cornnients on the idea of a non-glaciated barents sea even though the shoreline displacement in east ern svalbard strongly indicates the presence of a late weichselian ice sheet in the northern bar ents sea. the possibilities of a non-glaciated north ern barents sea should be taken into consider ation. such a concept implies that the blue-grey glaciomarine sediments in the area have to include deposits from the time when a former ice sheet retreated from the region. however, the sedi ments show no sign of erosion, reflecting the late weichselian regression. hiatuses can on the other hand be present as non-depositional episodes. the very low content of foraminifera (10 per 1oog sediment) makes stratigraphical interpretation problematic. the fauna observed in the cores from the northern barents sea is composed of species with affinities to cold water, reflecting a high arctic glacial environment (fig. 6). this is in contradiction to the finding of p r e l a t e weichselian shells, drift wood, and whale bones on kong karls land, which in turn indicate a pre-late weichselian climate similar to the present (salvigsen 1981). a response to such conditions has not been traced in the samples. theoretically, these sediments could have been removed, but it seems reasonable that such an event should also be recorded in the the barents sea ice sheet 41 underlying sediment. however, the lowermost part of the blue-grey glaciomarine sediments are inadequately sampled and the existence of hia tuses cannot be totally rejected. a more detailed investigation of the stratigraphy of the blue-grey sediments is in progress. conclusion the sediment sequence of till (and/or glacio marine sediments overrun by a glacier) overlain by glaciomarine deposits which in turn grade into postglacial sediments (holocene age), demon strates that the western and northern (west of 35"e) barents sea has at least once been covered by grounded ice. moraine ridges along the western continental shelf edge, especially at the mouth of b j ~ r n ~ y r e n n a , indicate the occurrence of a large-scale glaciation in the barents sea. moraine ridges and thick glaciomarine accumulations are found radially to spitsbergenbanken at 150 to 200 m and 250 to 300 m water depth, respectively. at the same water depths, similar ice marginal features are also found in the central and northern barents sea. based on these features and regional geological considerations we propose the exist ence of a marine ice sheet covering the northern part of the barents sea and spitsbergenbanken during the late weichselian. whether this ice sheet represents a major halt during the retreat of a more extensive ice sheet or the outer limit, is not clear. it should be noted that such a model is in conflict with: (1) the idea of large-scale, catastrophic break-up at the end of the late weichselian as sug gested by grosswald (1980) and denton & hughes (1981); (2) the existence of a late weichselian ice shelf covering the norwegian-greenland sea, as proposed by kellogg (1980); and (3) the idea of a non-glaciated barents sea, as suggested by boulton (1979a, b). acknowledgements. shallow seismic data and sediment samples were collected during the barents sea project funded by the royal norwegian council for industrial and scientific research and the norwegian petroleum directorate (npd). we thank yngve kristoffersen for organizing the 1977, 1978, and 1980 field work providing the data base for this study. additional shallow seismic data were kindly made available by npd. colleagues at the norwegian polar research institute, together with adrian read and jan mangerud, are acknowl edged for valuable comments. the authors are indebted to jend nagy for foraminiferal analyses. references andersen, b . g . 1968: glacial geology of western troms, north norway. nor. geol. unders. 256, 160 pp, andersen, b . g . 1981: late weichselian ice sheets in eurasia and greenland. pp. 1-65 in denton, g . h. & hughes, t. j . (eds.), the last great ice sheets, john wiley & sons. baranowski, s. 1977: the subpolar glaciers of spitsbergen seen against the climate of this region. wroclaw, wydawnrctwa uniuersyfetu wrochawskeiyo. results of inuestigation of the polish scientific spitsbergen expenditions 3 , 93 pp. bjdrlykke, k . , bue, b. & elverhdi, a . 1978: quaternary sedi ments in the northwestern part of the barents sea and their relation to the underlying mesozoic bedrock. sedimentology 25, 227-246. boulton, g . s . 1979a: glacial history of the spitsbergen archi pelago and the problem of a barents shelf ice sheet. eoreus boulton, g. s . 1979b: a model of weichselian glacier variation in the north atlantic region. eoreas 8, 37s395. damuth, j. e . 1978: echo character of the norwegian-green land sea: relationship to quaternary sedimentation. marine geology 28, 1-36. denton, g . h. & hughes, t . j . 1981: the arctic ice sheet: an outrageous hypothesis. pp. 437-467 in denton, g . h. & hughes, t. j . (eds.), the last great ice sheets, john wiley & sons. dibner, v. d . 1968: 'ancient clays' and the relief of the barents-kara shelf as direct proof of its sheet glaciation during the pleistocene. pp. 1 2 4 1 2 8 in belov, m. i . (ed.), problems of polar geography, trudy 285. dreimanis, a . 1978: till and tillite. pp. 805-810 in fairbridge. r. w. & bourgeois, j. (eds.), encyclopedia of sedimentology encyclopedice of earth sciences series 6. elverhdi, a . & kristoffersen, y. 1977: glacial deposits south east of bjdrndya, northwestern part of the barents sea. norsk polarinstitutt arbok 1977, 2 w 2 1 5 . elverhdi, a. & bomstad, k . 1980: late weichselian glacial and glaciomarine sedimentation in the western, central bar ents sea. unpubl. rep., norsk polarinstitutt, 1980. 29 pp. grosswald, m. g. 1972: glacier variations and crustal move ments in northern european russia in late pleistocene and holocene times. pp. 205-221 in vasari, y . , hyvarinen, h . & hicks, s . (eds.), climactic changes in arctic areas during the last ten-thousand years. acta unioersitatis ouluensis, oulu, finland 1972. grosswald, m. g. 1980: late weichselian ice sheet of northern eurasia. quaternary research 13, 1-32. grosswald, m. g., lavrov, a . s . & potapenco, l. m. 1974: the markhida-velt ice advance: a twin-surge of the barents ice sheet? materialy glyatsiol. issled. khronika obsuzhde niya 24, 173-188. (in russian with an english summary.) haggblom, a . 1982: driftwood in svalbard as an indicator of sea ice conditions. geogr. ann. 6 4 a , 81-94. hoppe, g. 1970: the wiirm ice sheets of northern and arctic europe. acta geographica lodziensia 24, 105-1 15. hoppe, g . 1981: glacial traces on the island of hopen, sval hard: a correction. geogr. ann. 6 3 a , 67-68. 8 , 31-57. 42 a , elverhbi & a . solheim hoppe. g.. shytt. a . . haggblom. a . & osterholm, h . 1969: the glacial histoy of hopen. geogr. ann. 5 1 a , 185-192. hughes. t . j.. denton. g . h . . andersen. b. g.. schilling, d . h.. fastook. j . l . & lingle, c. s . 1981: the last great ice sheets: a global view. pp. 263-317 in denton. g . h . & hughes, t . j . (eds.). the lasr great ice sheetr. john wiley & sons. hyvarinen, h. 1972: pollen-analytic evidence for flandrian climatic change in svalbard. pp. 225-237 in vasari, y . , hyvannen, h . & hicks, s . (eds.), climafic changes in a r m c areas during the lasr ten-rhousand years. acra u n i ~ e r s i r ~ ~ r i s ouluensb, oulu, finland 1972 kellogg, t . b. 1980: palaeoclimatology and paleo-oceanogra phy of the norwegian and greenland seas: glacial-interglacial contrasts. boreas 9 . 115-137. knape, p . 1971: c-14 dateringar av hmjda strandlinjer, synkrona pimpsrensnioder och rakttageher av hmgsra kusrlinjen pd s l a l bard. unpubl. lic dissert.. stockholm univ. naturgeogr. inst. 142 pp. koteniov, b . n.. matishov, g . g . , belyayev. a . v. & mys livets. v . i. 1976: geomorphology of the shelf and continental slope between spitsbergen and north norway. priroda i khozyaictvo seuera 4 , 3cl38. (in russian.) kristoffersen, y.. milliman. j. d . & ellis. j . p. in press: unconsolidated sediments and shallow structure of the north ern barents sea. polar research. kvasov. d. d . 1978: the barents ice sheet as a relay regulator of glacial-interglacial alternation. quaternary research 9. matisov. g . g . 1980: geomorphological indications of the impact of the scandinavian, novaja zemlja, and the spits bergen ice cover upon the surface of the bottom of the barents sea. (geomorfologiceskie priznaki vozdejstvija skacdinav skogo, novozemel'skogo, spicbergenskogo lednikovych pok rovov na poverchnost'dna barenceva morja.) in: okeanol 2 8 a m ogija xx (4) 1980, 669-680. english summary. p. 680. udc 551-35:551.463 (261). translated (12 pp.). april 1981. rokoengen. k.. bugge, t . & l ~ f a l d l i . m. 1979: quaternary geology and deglaciation of the continental shelf off troms. north norway. boreas 8, 217-227. salvigsen, 0. 1977: radiocarbon datings and the extension of the weichselian ice-sheet in svalbard. norsk polarinsritutt arbok 1976, 209224. salvigsen, 0. 1978: holocene emergence and finds of pumice, whalebones, and driftwood at svartknausflya, nordaustlan det. norsk polarimrirutr a r b o k 1977, 217-228. salvigsen. 0. 1981: radiocarbon dated raised beaches in kong karls land, svalbard, and their consequences for the glacial history of the barents sea area. geogr. ann. 6 3 a , 2 8 s 2 9 1 . salvigsen, 0. & nydal, r . 1981: the weichselian glaciation in svalbard before 15,000 b.p. boreas 10, 433-446. schytt, v. 1969: some comments on glacier surges in eastern svalbard. can j . earth. scr. 6 , 867-873. semevsky, d . v. 1967: neotectonics of the spitsbergen archi pelago. pp. 225-238 in materialy p o srrarigrafii spitsbergena. solheim. a . & elverhmi, a. 1982: marin-geologiske og -geo fysiske unders~kelser 1981. toktrapport og forebpige resul tater. norsk polarimtitutr rapport n r . 7. 88 pp. thomas. r. h . 1979: the dynamics of marine ice sheets. journal of glaciology 24, 167-177. vorren. t . 0.. strass, i f. & lind-hansen, 0. w . 1978: late quaternary sediments and stratigraphy on the continental shelf off troms and west finnmark, northern norway. qua ternary research 10, 34c-365. vorren, t . 0. & elvsborg. a . 1979: late weichselian degla ciation and paleoenvironment of the shelf and coastal areas of troms, north norway-a review. boreas 8, 247-253. williams. p. j. 1967: the nature of freezing soil and its field behavior. norwegian geotechnical instirure publ. no. 72: 9&119. por_025.fm polar research 26 2007 107 – 112 © 2007 the author 107 blackwell publishing incmalden, usaporpolar research0800-03952007 blackwell publishing ltd? 2007262107112original article melting ice—a hot topic?h. b. bäsemann f r o m t h e c o n f e r e n c e m e lt i n g i c e — a h o t to p i c ? melting ice—a personal view of climate change hinrich b. bäsemann polarfoto, p.o. box 1141, no-9261 tromsø, norway. e-mail: basemann@online.no i first crossed the arctic circle on my way north in the early 1970s. i visited the glaciers in swedish lappland and norway’s rugged lofoten islands. apart from the natural beauty of the area, my main interests were climate and geological history, as i was then working towards a doctoral degree in glacial and marine geology, which i earned in the late 1970s. since then i have been in the far north nearly every year. in the beginning i travelled in the scandinavian mainland; later i saw iceland, svalbard and greenland. special highlights were the northwest and northeast passages. the first time i recognized changing glaciers was in the rocky mountains of britsh columbia and at glacier bay national monument in south-east alaska. several journeys to the latter place gave evidence for retreating ice, as shown in two photographs of mcbride glacier, taken in 1980 and 1989. as i saw retreating glaciers in norway (jostedalsbreen, svartisen, briksdalsbreen) and in north america i was told “these are natural processes; other glaciers are advancing”. since then i have seen many glaciers in svalbard and on greenland: nearly all of them in retreat. the drift ice in the arctic ocean is also affected, in terms of its age, thickness and surface area. i have seen the arctic ice from the norwegian polar institute’s research vessel lance , the university of tromsø’s jan mayen and the alfred wegener institute’s polarstern , and from several ice-breakers and cruise ships. you only see the differences when you come back again and again and—most important—when you also talk to the arctic’s indigenous peoples. inuit people in greenland, nunavut and alaska told me that they are very much concerned about the huge loss of ice. their traditional foods, like seals, whales, polar bears and birds, have also changed their behaviour. the summers are becoming warmer: the ice comes later in the fall and disappears earlier in the spring after a mild doi:10.1111/j.1751-8369.2007.00025.x iceberg and summer ice, east greenland. 108 polar research 26 2007 107 – 112 © 2007 the author melting ice—a hot topic? h. b. bäsemann mcbride glacier, alaska, 1980. mcbride glacier, alaska, 1989. researchers working on summer ice in the arctic. summer ice in the arctic. h. b. bäsemann melting ice—a hot topic? polar research 26 2007 107 – 112 © 2007 the author 109 inuit woman preparing fish and seal meat in holman, victoria island, canada. young harp seal on the ice. polar bear family feeding on a seal, northwest passage, 1999. winter. ice is essential for many species. several seal species give birth to their cubs only on ice, polar bears catch their prey only on ice, and some birds find their fish and krill only in drift ice. one of the most impressive views i had was the melting permafrost in the tundra. after a visit in 1999 to herschel island, in north-west canada, i came back in 2006. in 1999 there had been lots of ice in the northwest passage. seven years later—in the same month (august)—there was nearly no ice. but on herschel island itself i saw the most striking sight: black spots in the tundra and at the coastal cliffs. the black spots— melting permafrost—look like wounds or lesions. sediments are washed out to the sea, blocking out the 110 polar research 26 2007 107 – 112 © 2007 the author melting ice—a hot topic? h. b. bäsemann sunlight and obstructing marine algae’s photosynthesis. satellite photographs of recent years confirm this development all over the north. another effect is the release of additional greenhouse gases like carbon dioxide and methane into the atmosphere. i faced this phenomenon—without knowing what it was—in 1982 during an excursion to the lena river in sibiria as part of the international quarternary congress in moscow. russian scientists presented us with newly emerged lakes in the taiga. normal permafrost and pingos had melted and disappeared in only a few years, and large larch trees had toppled over and rolled down to the river banks. the kittiwakes fighting over a polar cod. polar bear ashore, bellot strait, northwest passage, 2006. ice-free gjoa haven, nunavut, canada. h. b. bäsemann melting ice—a hot topic? polar research 26 2007 107 – 112 © 2007 the author 111 thawing tundra on herschel island, canada. thawing tundra on the north-western canadian arctic coast. thawing taiga on the lena river, near yakutsk, russia, in 1982. young boy in greenland. inuit children, qaqortoq (julianehåb), greenland. 112 polar research 26 2007 107 – 112 © 2007 the author melting ice—a hot topic? h. b. bäsemann reason was unknown at that time—25 years ago. now we know. more than 30 years of taking pictures in these remote environments [see www.polarfoto.com—the editor] has given me an impressive documentation of what has happened and what is happening now. i know this pictorial record, my contribution to this conference, is not scientific proof of climate change in the arctic. but my observations and experiences all point in the same direction. i live in tromsø, on the edge of the arctic, and am approaching retirement. i want to help—especially young people—to understand what is happening. the arctic children are concerned wherever they live. what will be their future when the ice has gone? young girl in the village of uelen, chukotka autonomous okrug, russia. polar bear, hornsund, svalbard. pleistocene sea level changes and glacial history of the hornsund area, svalbard henryk chmal chmal, h. 1987: pleistocene sea level changes and glacial history of the hornsund area, svalbard. polar research s n . s . , 269-270. henryk chmal, geographical imtitute, university of wroclaw, pl. uniwersytecki 1, 50-137 wroclaw, poland. the first radiocarbon datings of shells and whale bones from raised marine terraces of hornsund (birkenmajer & olsson 1970) showed that with regard to quaternary geology south spitsbergen is very different from the rest of svalbard. bir kenmajer & olsson (1970) concluded that the 7 . 5 9 . 0 m terrace is about 9,400 years b.p. (uncorrected). this altitude is un usually low in comparison with other svalbard regions where in the preboreal-boreal period the relative sea-level was 3c-50 m or even 70m higher than today (salvigsen 1981). on the other hand, in the hornsund area very high terraces were recorded. werenskiold (1922) reported the existence of a 340m terrace in s ~ r k a p p land. in steinvikdalen, jahn (1959) found a well developed pebble beach at 2 w 2 3 0 m level as well as evidence of sea washing reaching 275 m a d . the geochronological interpretation of marine and glacial deposits of the hornsund area in this paper is based on geomor phological investigations and new radiocarbon, and t l dates. marine terraces the age of the 7-9 m terrace has been determined by comparing radiocarbon datings from three sites. on store d u n ~ y a , below a 2 m layer of upper pebbles, peat was found and dated at 7,250 years b.p. i n nottinghambukta, in the lower part of an exposed section in the 7 m terrace there is sea tangle (laminaria) which has been dated at 7,690 ? 90 years b.p. the upper part of the section consists of pebbles with shells dated at 7.230 ? 50 years b.p. in burgerbukta, on the surface of the 9 m terrace a piece of driftwood was found and dated at 5,050 ? 60 years b.p. the samples have been dated by m. pazdur at gliwice. the interpretation of these datings is as follows: the deposits of the 7-9 m terrace reflect a marine transgression which lasted from about 7,200 to 5,000 years b.p. this transgression reached the 9 m level which the shore had passed during the regression 9.400 years b.p. (birkenmajer & olsson 1970). during the period 8.00&7,200 years b.p. the sea oscillated at a level of 1 4 m a d . which is the highest level reached by the sea during the late vistulian (=weichselian)-early holocene time? the shoreline corresponding t o this level has been determined on the basis of detailed geornorphological studies, and it is 25 m in hornsund and 32 m in the area between torellbreen and orvindalen. if the early holocene emergence of svalbard is the result of a glacio-isostatic effect, then this effect was weakest in hornsund. hence it may be concluded that during the main vistulian (18,000 years b . p . ) this region was the one least loaded with ice. the middle-vistulian marine transgression, about 4 5 , w 27,000 years b.p., is known from many regions in svalbard. based on geomorphological observations we may conclude that at that time the sea in the hornsund region reached a maximum level of 3 6 4 2 m. in turrsjodalen the 38 m terrace is built of deposits which originally made a sandur. it is cut off by a 7 m cliff which could have developed only during the early holocene marine transgression. thus, the 38 m terrace is probably of a vistulian age. the thermoluminescence (tl) datings suggested the age of this terrace to be 27,000 ? 4,000 years (dated by j . butrym at luhlin). the altitude of the middle-vistulian shore line is rather small. hence we may suppose that the glaciers during early vistulian and main vistulian were small as well. the uppermost marine terraces occur in the hornsund area at an altitude of 22c-230m. starting from steinvikdalen we traced the highest shoreline along the west coast of spitsbergen, and this level descends northwards. at the mouth of bellsund it is about 120m. it should be noted that mangerud et al. (this volume) consider these 'terraces' to be much older rock platforms of uncertain origin. if we assume the local elevation of this shore level to be proportional to the thickness of the ice that covered the land during the corresponding glaciation, we might infer that the hornsund area was the centre of a thick ice sheet during that glaciation. in accordance with former suggestions. this glaci ation must he of pre-vistulian age. probably of late saalian age. a similar opinion was presented by feyling-hanssen & ulleberg (1984) for the sarsbukta area. glacial deposits in the large valleys of the hornsund region only one type of basal till was observed lying on bedrock. likewise, o n the bottom of the hornsund fjord only basal till occurs, covered by sandy and muddy deposits of a thickness of several dozen meters (zalewski et al. 1984). in the large valleys the basal till is reworked by the sea to 120-230m level. thus, the basal till represents a record of the great pre-vistulian glaciation of the hornsund area. counterparts of the upper vistulian till, known from other regions of spitsbergen (landvik & salvigsen 1985), can in the hornsund area only be found in small, nonglaciated cirques and in the glacier forefields. also the moraines of no longer existing slope glaciers as well as those of rock glaciers may be regarded as corresponding with the upper till. the vistulian till never extends more than 1 km outside the ice-cored moraines from 270 henryk chmal the little ice age. in burgerbukta we can prove that the miihlbacher, kvalfangar and wiber glacier group extended further during the little ice age than during the main vistulian. references birkenmajer. k. & olsson, 1. u . 1970: radiocarbon dating of raised marine terraces at hornsund, spitsbergen. and the problem of land uplift. norsk polarinstirun arbok 1969. 17 43. feyling-hanssen, r. & ulleberg. k. 1984: a tertiary-quat ernary section at sarsbukta. spitsbergen, svalbard, and its foraminifera. polar research 2 n . s . , 77-106. jahn, a . 1959: the raised shorelines and beaches in hornsund and the problem of postglacial vertical movements of spitsbergen. przegl. geogr. 31 (suppl.), 14s178. landvik, j . y. & salvigsen, 0. 1985: glaciation development and interstadial sea-level on central spitsbergen, svalbard. polar research 3 n . s . , 1-10, salvigsen, 0. 1981: radiocarbon dated raised beaches in kong karls land. svalbard, and their consequences for the glacial history of the barents sea area. geogra. ann. 63a, 283-291. werenskiold, w. 1922: heie strandlinjer paa spitsbergen. nor. geol. tidsskr. vii ( i ) , 7-12. zalewski. s. m., kowalewski, w.. rudowski, s. & rossa, w. 1984: preliminary results of seismoacoustic sounding of sea sediments in the region of spitsbergen. sympozjum spits bergen '84. inst. ekologii p a n , 12. the geological implications of the upper seismic unit, southeastern barents sea j o a r s e l t e m and martin hamborg saettem, j. & hamborg, m. 1987: the geological implications of the upper seismic unit, southeastern barents sea. polar research 5 n . s . , 299-301. joar settem and martin hamborg, continental shelf and petroleum technology research institute, h d k o n magnussonsgt. i b , p.o. box 1883 jarleslerta, n-7002 trondheim, norway. occurrence an upper quaternary seismic unit has been mapped to the east and southeast of b j e r n ~ y r e n n a in the barents sea. the unit is dcfined by interpretation of shallow seismic (sparker) data, and occurs as an upper, seismically transparent sequence in the quaternary succcssion. discontinuous internal reflections do, however, occasionally occur, especially in the lower part of the unit. the sediments in the unit are interpreted to be of a glaciogenic origin and they most likely consist mainly of tlll. the unit wedges out towards thc west in present water depths generally between 300 and 400 m (fig. 1). in b j 6 m ~ y r e n n a the unit has bccn mapped down to more than 440 m water depth. the unit is mapped northwards to approximately 74"n, but it continues farther. its eastern boundary is mapped only in a small area. the boundaries are partly uncertain due to limitations in the resolution of the data (approximately 10 m). it is thus possible that the unit occurs in a far wider area than the one presently mapped. stratigraphic relations the base of the unit is defined partly by a strong, smooth and continuous reflection, partly by a weak and irregular reflection. the latter type, which locally resembles iceberg ploughed sea bed relief. dominates in the western part of the unit. in the east the unit is in some areas overlying older quat ernary sediments, whereas it partly rests directly on the upper regional angular unconformity (top pre quaternary sediments). samples from shallow drilling in the area show that the sedi ments immediately above the unconformity are diamictons of glacial origin. the last erosional phase of the unconformity will in large areas most probably comprise several episodes of glacial erosion. this concurs with the observations by solheim & kristoffersen (1984) farther west and vorren et al. (1986) farther south. the glaciogenic sediments below the mapped unit become continuous and thicken westwards, normally to 50-75 m. the mapped unit occurs above a locally more than 200111 thick seismically transparent succession in ingeydjupet. this relation is, however, uncertain due to lack of seismic data. a n equahy probable interpretation is t o include parts of the succession in ingeydjupet in the upper seismic unit. towards the north, in eastern bjorneyrenna, an intra quat ernary reflection occurs which could represent the base of the mapped unit. this, however, remains to be solved. the west ward thinning of this unit in a part of western nordkappbanken is clearly seen on the iku deep towed boomer records (fig. 2). generalized sediment description push samples and hammer samples from the described unit have been obtained by shallow drilling at 6 locations. these samples are obtained at depth intervals of 5-10 m from 8 m down to approximately 30 m below the sea bed. the samples comprise silty clay with some sand and scattered fragments of gravel and pebble size. the grain size distribution is fairly uniform for all the sites: 35-45% clay and 30-40% silt. the sediment colour, according to the munsell colour chart, is grey (5 y 4/1) to very dark grey (5 y 3/1), occasionally dark olive grey (5 y 3/2). geotechnical properties the soil mechanical tests reveal a clearly overconsolidated sediment. natural water content ranges from 16% to 35% (in per cent of dry weight). the water content is often close to the plasticity limit, which is normally about 20%, and always well below the liquid limit which is found at 40-50%. undraincd shear strength, s,, is measured by falling cone and triaxial testing. the values range from approximately 30 kn/m2 to approximately 370 kn/m2. the latter value is recorded about 10 m below the sea bed at the easternmost drill site. oedometer tests are done on 7 samples from depths ranging from 8 to 23 m. measured effective preconsolidation pressure ranges from 120 to 800 kn/m2. the overconsolidation ratio varies from 1.5-7.0. neither of these parameters should, however, be used directly to calculate maximum static effective vertical load, as it is uncertain what could be the effect on recorded preconsolidation of shear from the ice during and after deposition. inferred depositional history our present interpretation is that the unit consists of sediments mainly deposited as basal till. exceptions may be an upper blanket of late weichselian glaciomarine and holocene sedi ments a few metres thick. in the eastern part of bjejrnqyrenna 300 joar sattem & martin hamborg fig 1 the upper quaternary seismic unit based on seismic interpretation. typical thickness variations are shown in the thickne\s diagram\ (approximately 73'10'n. 26"w'e) there is a local occurrence of acoustically stratified sediments. deep towed boomer data indicate that these sediments are deposited contemporaneously with the till. close to the grounding line. hut on the distal side (king & fader 1986: kmg et al. 1987). the unit i s clearly older than the deglaciatlon of the ares which happened before 13.290 b, p. (vorrcn & kristoffersen iy86) vorren & krictoffcrsen (iy86) argue for a maximum late weichselian icc sheet margin 1 0 0 k m west of thc area described herein. the seismic stratigraphic correlation between thc two areas is not evident preliminary evaluation of amino acid measurement5 does, howckcr. indicate an agc younger than 2l).o(m b p tor the mapped unit. the entire unit is interpreted to be deposited during one glacierization in the area. however, a faint internal reflection outlines an up to 50 m thick sediment wedge on the shallowest part of nordkappbanken. this evidence suggests a multi-epi sode formation of the unit which may include several gla cierizations. or, as we find equally likely, shifts in zones of erosion and deposition and of grounding line position during one glacierization. a tentative interpretation is that the mapped unit (or part of i t ) was deposited during the last glaciation in the area. during much of the deposition of the unit thc ice sheet grounding line was probably located close to the western boundary of the unit. local observations on deep towed boomer data support this interpretation the mapped unit could possibly be correlated with the deepermost marginal features along the northwestern geological implications of upper seismic unit 301 fig. 2. the high resolution boomer profile shows the westward termination of the described upper seismic unit. an overlying thin stratified layer thins out both eastwards and westwards. flank of b j ~ r n d y r e n n a observed by elverhdi & solheim (1983, fig. 14). westward thinning of the unit could, however, also be the result if meltout of basal debris ceased to the east of the mapped western boundary. alternatively, the thinning could (at least locally) be due to erosion. references elverhdi. a . & solheim. a. 1983: the barents sea ice sheet a sedimentological discussion. polar research 1 , 23-42. king. l . h . & fader. g . b . j . 1986: wisconsinan glaciation of the atlantic continental shelf of southeast canada. geological survey of canada 363, 1-72. king, l. h., rokoengen. k . & gunleiksrud. t. 1987: quat ernary seismostratigraphy of tranabanken and adjacent areas. continental shelf institute publication no. 114. solheim, a. & kristoffersen. y . 1y84: the physical environ ment western barents sea, 1: 1,500.000. sediments above the upper regional unconforrnity: thickness. seismic stratigraphy and outline of the glacial history. norsk polarinstitutt skr. 1798. vorren, t. 0.. kristoffersen. y. & andreassen. k. 1986: geo logy of the inner shelf west of north cape, norway. norsk geologisk tidrskrift 66, 99-105. occurrence of pumice on raised beaches and holocene shoreline displacement in the inner isfjorden area, svalbard otto salvigsen salvigsen, 0. 1984: occurrence of pumice on raised beaches and holocene shoreline displacement in the inner isfjorden area, svalbard. polar research 2 n.s., 107-113. finds of pumice on raised beaches in the inner isfjorden area are reported. pumice is abundant in two zones, and four levels can be distinguished in some areas. the highest lying level has the greatest concentration of pumice and is dated to a maximum of 6,500 years b.p. tentative correlations with pumice levels from other places in svalbard indicate approximate ages of 6,000, 4,100, and 3,100 years for the lower levels in inner isfjorden. a shoreline displacement curve based on the pumice levels and on 10,ooo year old driftwood is presented. otto salvigsen, norsk polarinstitun, rolfstangueien 12, 1330 oslo lufthavn, norway. introduction scattered finds of pumice on raised beaches were reported by several expeditions visiting svalbard in the previous century, e.g. parry (1828), and nordenskiold (1863, 1874). the first systematic study of this subject was conducted by donner & west (1957) followed by blake (1961), who introduced the radiocarbon dating method to pumice investigations in svalbard. schytt et al. location m a p s fig. i. location map of svalbard. (1968) presented an isobase map for the 6,500 year-old shoreline in svalbard, based mainly on pumice observations. later, boulton & rhodes (1974) and salvigsen (1978,1981) studied pumice on raised beaches and dated several levels where pumice was abundant. to my knowledge only peder knape has reported finds of pumice on raised beaches in the inner isfjorden area. de geer (1896) and other scientists reported pumice which was most likely found near the present shore. knape (1971) found pumice 21m above sea level at bjonapynten between tempelfjorden and sassenfjorden. balchin (1941), feyling-hanssen (1955) and pew6 et al. (1982), among many others, have made detailed studies of raised beaches in inner isfjorden, but without reporting pumice. it is also a striking fact that only one record exists of pum ice finds elsewhere on the west coast of spits bergen (salvigsen 1984). the main purpose of this paper is to present finds of pumice in an area where they have not previously been reported. a holocene shoreline displacement curve has also been drawn, based on pumice observations and two new radiocarbon dates. field observations the quaternary geology of billefjorden and dicksonfjorden was studied in 1981, and pumice was looked for in raised beach areas where con 108 otto saluigsen fig. 2. the inner isfjorden area showing the sites where pumice was observed. see table 1 for site names. ditions seemed promising for such finds (fig. 2). an elevation of 10.8 m at blomesletta (lo), the altitudes were measured by precise levelling between ekmanfjorden and dicksonfjorden, from an estimated mean tide level. three altiwhere undisturbed raised beaches exist. in dick meter determinations (paulin) are also included. sonfjorden, however, most of the raised beaches sites and altitudes of observed pumice levels are are covered by vegetation and it is impossible to shown in table 1 and figs. 2 and 3. find pumice there. only one locality, myggdalen pumice was observed t o be abundant around (9), has bare, undisturbed beaches at an appro table 1. pumice observations. location of site altitudes in m above mean tide level 1. brucebyen (6) 9.0 10.2 17.5 2. ekholmvika 14.4 15.6-17.018.3 3. kapp ekholm 5.3 6.2 7.5 8.38.4 4. alvrekdalen 15.9 5. mytilusbekken (7) 7. gipsvika 7.6-10.011.3 (17) 8. bjonapynten 21 6. gasodden 9.9 19.5 20.5 9. myggdalen 6.7 14.1 10. blomesletta 6.7 7.7 9.8-10.812.0 for location, see fig. 2. altitude numbers connected by dashes define range of pumice. altitudes with specially high concentration of pumiceareinitalics, whilealtitudesin bracketsweremeasured by pauline altimeter. occurrence ofpumice, isfiorden area 109 (fig. 3). the vertical distribution of pumice in these zones is considerable, and it seems likely that this also represents a spread in deposition time. it is usually possible in the field, however, to distinguish distinct, main levels where pumice is most abundant. these concentrations of pumice are considered to represent synchronous events. several problems make it difficult to determine the exact tilt of pumice levels in an area as small as the one dealt with here. some uncertainty is attached to the determination of the mean tide level in each site where pumice was observed. the main problem, however, is that the actual pumice sites have had varying exposure to the waves, and the pumice has therefore been deposited at different heights above mean tide level. the slope of the shore and offshore top ography are important factors in determining the elevation at which pumice will be deposited. the highest pumice was found at gasodden (6) which faces southwest and has no protection against storm waves from the mouth of isfjorden. most of the other raised beaches with pumice have been formed under conditions of shorter fetch, i.e. waves coming across the fjord or from the head of the fjord, and on these beaches pumice has not been thrown as high as at gasodden. within the pumice zones (shaded in fig. 3), straight lines (a and c) have been drawn to show tentatively the approximate tilt of the two levels with the highest pumice concentration in inner isfjorden. below both these levels there are indications of additional pumice levels (b and d). these two less distinct levels appear most clearly in the ekholmvika-kapp ekholm area. priate altitude; two levels with pumice were observed, at 14.1 m and 6.7 m above sea level. pumice has probably been deposited extensively on the beaches of dicksonfjorden during the holocene. however, most of the beaches have either been destroyed by subsequent slope pro cesses or have become covered by vegetation, so it is unlikely that many new finds will be made in this fjord. the area between dicksonfjorden and billefjorden is also characterized by rich veg etation, and no pumice was found there at all. the occurrence of pumice on the western side of billefjorden is very limited, with only five pieces being discovered near the mouth of alvrekdalen the raised beaches on the eastern side of billefjorden consist in several places of beach ridges on sloping plains as described by feyling-hanssen (1955) and others. pumice was observed at five localities as well as in one locality at gipsvika (7) between billefjorden and tempelfjorden. the highest concentration of pumice was found at blomesletta (lo), where pumice pieces were more concentrated than i have seen at any other site in svalbard. in many places more than 10 pieces could be found in 1 m2. high concentra tions of pumice were found at four different levels in the area of ekholmvika (2) and kapp ekholm the colour of the pumice on the raised beaches in inner isfjorden can be characterized as greyish black with shades of brown. there is no colour difference between the different pumice levels in isfjorden, and the pumice there seems to have the same colour as the pumice elsewhere in sval bard. the pumice pieces are of varying size though usually less than 8cm in diameter. the largest piece found in inner isfjorden is approxi mately 15 cm in diameter. (4). (3). pumice levels fig. 3 shows a distance diagram where pumice sites and altitudes have been projected perpen dicular to a plane (a-b in fig. 2). the direction of this projection plane is approximately perpen dicular to the 6,500 year isobase presented by schytt et al. (1968). as expected the altitudes of observed pumice d o not fall on straight lines in the projection plane, but are grouped in a way that indicates two pumice zones in inner isfjorden age determinations and correlations the highest or main pumice level in svalbard has been radiocarbon dated using wood and whale bones associated with this level (blake 1961; knape 1971; boulton & rhodes 1974). its average age is 6,500 years and a similar age was also expected for the highest pumice in isfjorden. this was confirmed by a date on m y t h edulis shells from gasodden (6). the main pumice level there has an elevation of 19.5 m, and scattered pieces of pumice were found up t o 1 m higher. the shell fragments were sampled from the surface, 18.1 m above sea level, and gave an age of 6,440 k 80 110 otto salvigsen fig. 3. distance/elevation diagram of pumice observations in inner isfjorden. projection axis is line a-b in fig. 2. +: precisely levelled pumice observation, (+): pauline determined pumice observation. vertical arrows show the height range of pumice associated with each of the pumice levels. pumice occurs mainly in two zones (shaded), and within them four levels, a-d. have been distinguished. years b.p. (t-4628). the mussel mytilw edulis is generally restricted to shallow water, often within the intertidal zone, and has proved to be a species which can be used to date the position of former sea levels (donner et al. 1977). it there fore seems likely that the dated sample represents molluscs living contemporaneously with, or shortly before, the deposition of pumice at gbodden. the main pumice level, a, exists in inner isfjorden, and 6,500 b.p. is considered a maximum age. the lower pumice levels in isfjorden have not been dated because suitable material for their exact dating was not found. however, probable correlations and ages will be discussed. boulton & rhodes (1974) distinguished a pumice level a few hundred years younger than the main horizon on the north coast of spitsbergen. in inner isfjorden, too, there are indications of a pumice level deposited shortly after level a. it is most clear in ekholmvika (2) where the vertical dis tance between a and b is 2.6m, indicating that the lowest pumice could have been deposited about 6,000 years ago. at some sites level b may well be hidden due to the spreading of pumice below level a, e.g. at blomesletta (10). next to level a, level c is the most prominent pumice level in inner isfjorden. it may possibly be a correlative of boulton & rhodes (1974) level c on the north coast of spitsbergen, dated by them at 4,000-4,150 years b.p. similar ages have also been found for pumice-bearing strandlines in north norway and britain (binns 1967). an alternative correlation in svalbard is with the pumice level on the southern coast of nordaust landet, dated to about 4,500 years b.p., and it occurrence ofpumice, zsforden area 111 90 80 70 60 50 40 30 20 10 0 -r is possible that the lower pumice level along hinlopen is also from that time (salvigsen 1978). the upper pumice level in kong karls land was dated to about 5,200 years b.p. (salvigsen 1981), but up to now this level has only been found as a local level on kongscdya. at present, ages of about 4,100 and 4,500 years are therefore most plausible for level c in isfjorden. the lowest pumice, level d , was only found as a distinct level at kapp ekholm (3), but at other sites a few pieces of pumice can probably be correlated with this level. the best guess for a correlative to this level in svalbard is probably the lowest pumice level in kong karls land, dated at about 3,100 years b.p. (salvigsen 1981). in addition to finds of pumice in the two raised pumice zones in inner isfjorden, several pumice pieces were usually found inside the modern shingle ridges on the same level as, o r below, the crest of these ridges. pumice on this level is in many cases difficult to distinguish from other slag products having reached the shores of spitsber gen. this pumice near the present shore cannot be established as a synchronous level. this study and previously referred studies from other parts of svalbard indicate at least six pumice levels younger than 6,500 years. they are very difficult to correlate from one site to another, and radiocarbon dating from as many localities as possible is desirable. it is clear that during the holocene there were several episodes when large amounts of pumice drifted ashore in svalbard and it seems likely that more pumice can be found there than in other arctic areas with raised beaches. 10 9 8 7 6 5 4 3 2 1 0 holocene shoreline displacement two new age determinations plus the recently discovered pumice levels make it possible now to present a new emergence curve for billefjorden (fig. 4). a piece of driftwood ( l a r k occidenralis) associated with the 65 m level at kapp ekholm (3) was dated t o 10,030, 140 years b.p. the main pumice level, a, at ekholmvika (2) is another fixed point for the shoreline displacement curve. its altitude is 17 m and its age is 6,500 years, as indicated previously. pumice levels b, c, and d have already been correlated to ages of 6,000, 4,100, and 3,100 years respectively, and these ages are used for the levels in the ekholmvika kapp ekholm area. fig. 4 shows an idealized i m a.s.l. fig. 4. shoreline displacement curve for the kapp ekholm ekholmvika area in billefjorden, based mainly on radiocarbon dates and pumice observations. two radiocarbon dates and four pumice levels are shown. shoreline displacement curve through the above-mentioned levels and ages. a shoreline displacement curve based on five shell dates from different ‘sites along the eastern shore of billefjorden was published by feyling hanssen & olsson (1960); see also feyling hanssen (1965) and pcwt et al. (1982). their curve shows somewhat older ages for the higher beaches than the curve presented here. this is partly due to the fact that the apparent age of recent shells in svalbard, about 500 years accord ing to mangerud & gulliksen (1975), had not been subtracted in the dates of feyling-hanssen & olsson. in addition, it should be remembered that shells are usually older than the levels at which they are found. the curve in fig. 4 is in agreement with two whale bone dates from billefjorden, u-506 and u-2077 in olsson et al. (1967,1969). because of the few dated points this curve does not ‘catch’ possible minor transgressions, but it can nevertheless be used for approximate age determinations of holocene shorelines in billefjorden. the marine limit is at least 9 0 m at kapp ekholm, and an extrapolation of the curve will give an age of between 10,500 and 11,ooo years 112 otto salvigsen for the marine limit at this site. the coastal morphology of the inner isfjorden area indicates that vertical land movements today are insignifi cant, if indeed they occur at all. discussion and conclusions binns (1967, 1971) has done the most thorough studies of the distribution and origin of pumice on raised beaches in northern europe and the western arctic. the new finds of pumice in inner isfjorden support the conclusion that the pumice has been transported to its present position by the surface currents of the gulf stream system. the extensive, distinct pumice levels found in svalbard (and elsewhere) and the abundance of pumice on these levels indicate that the drift pumice originates from rather large volcanic erup tions. comparative studies of chemical compo sition and mineralogy of the drift pumice and of the various possible centres have not produced conclusive evidence for the origin of the pumice (binns 1967, 1971; boulton & rhodes 1974). radiocarbon dates indicate a close coincidence in time between eruptions of hecla (iceland) and major drift pumice accumulations (binns 1967). however, the extensive distribution and the abundance of this pumice weighs especially against inland volcanoes like hecla as a source. the sources of the drift pumice are probably to be found among the volcanoes which delivered their material directly into the sea, but knowledge about submarine volcanoes of the past is almost non-existent. the new information about the main pumice level indicates that the 15 m isobase for the 6,500 year level in schytt et al. (1968, fig. 3) has a somewhat too westerly position in the isfjorden area. previous determinations of marine limits in the area have been confirmed. it decreases from about 96m in sassenfjorden to about 90m in billefjorden (feyling-hanssen 1965) and to about 62 m at blomesletta (pcwc ec al. 1982). the emergence curve for kapp ekholm is similar to the curves presented by feyling-hans sen & olsson (1960) and pcw6 et al. (1982). it is an asymptotic curve showing that the glacio isostatic rebound movement started before 10,000 b.p. the high rate of uplift between 10,ooo and 8,000 years b.p. (average 1.9tn/century) slowed down to a much lesser rate (average 0.45 rn/cen tury) between 8,000 and 4,000 years. in the latter period one or more transgressions are known from other areas (donner et al. 1977; synge 1980; hjort 1981; hafsten. 1983). feyling-hanssen (1965) found evidence of, and raised the question about, transgressions in billefjorden, but his conclusion was vague (p. 5 ) : ‘if a transgression, it seems probably to have taken place simultaneously with the late atlantic-early sub boreal transgression known from many other localities, e.g. in northern europe’. the new studies in inner isfjorden have not brought any evidence of transgressions in this area. the pumice levels are not connected with especially well developed beaches. neither has stratigraphic evidence been found of trans gressions in any of the sea-facing cliff sections in billefjorden, e.g. in ekholmvika, where a cross section in the raised, ridge beach plain was described by feyling-hanssen (1955). further investigations focusing on this subject are needed to get more information about possible holocene transgressions in svalbard. acknowledgements. during fieldwork yngve m. nilsen had a good eye for finding pieces of pumice. leif m . paulssen determined the driftwood species, and weston blake jr. and christian hjort read drafts of the manuscript and suggested improvements. thanks are expressed to those and to staff members of norsk polarinstitutt for their assistance in preparing the manuscript for publication. references binns, r. e. 1967: drift pumice on postglacial raised shore lines of northern europe. acta borealia a . scientiu 24. 64 pp. bims, r . e. 1971: the distribution and origin of pumice on postglacial strandlines in northern europe. and western arctic. m.sc. thesis (external) univ. of wales. 218 pp. balchin, w. g. v. 1941: the raised features of billefjord and sassenfjord west spitsbergen. geogr. j . 97, 364-376. blake, w. jr. 1961: radiocarbon dating of raised beaches in nordaustlandet, spitsbergen. pp. 133-145 in raasch, g. 0. (ed.): geology ofthe arctic, unv. of toronto press. boulton, g. s. & rhodes, m. 1974: isostatic uplift and glacial history in northern spitsbergen. geol. mag. 111 (6), 481-500. de geer, g. 1896 rapport om den svenska geologiska expe ditionen till isfjorden pa spetsbergen sommaren 1896. ymer, arg. 16,259-266. donner, j . j . & west, r. g. 1957: the quaternary geology of brageneset, nordaustlandet, spitsbergen. nor. polarinst. skr. 109. 29 pp. donner, j . j . , eronen, m. & jugner, h . 1977: the dating of the holocene relative sea-level changes in finnmark, north norway. nor. geogr. tidsskr. 31, 103-128. feyling-hanssen, r. w. 1955: stratigraphy of the marine late pleistocene of billefjorden, nor. polarinst. skr. 107. 187 pp. feyling-hanssen, r. w. 1965: shoreline displacement in central vestspitsbergen. nor. polarinst. medd. 93, 1-5. occurrence ofpumice, isfiorden area 113 feyling-hanssen, r. w. & olsson, i. u. 1960: five radiocarbon datings of post-glacial shorelines in central spitsbergen. nor. polarinst. medd. 86. 7 pp. hafsten, u. 1983: shore-level changes in south n o w a y during the last 13,000 years, traced by biostratigraphical methods and radiometric dating. nor. geogr. tihskr. 37, 63-79. hjort, c . 1981: present and middle flandrian coastal morphology in northeast greenland. nor. geogr. tihskr. knape, p. 1971: c-14 dateringer av h ~ j d a strandlinjer, synkrona pimpstensnivler och iakttagelser av h ~ g s t a kustlinjen pb sval bard. unpubl. lic. dissert. stockholms univ. naturgeogr. inst. 142 pp. mangerud, j . & gulliksen, s . 1975. apparent radiocarbon ages of recent marine shells from norway, spitsbergen and arctic canada. quaternary research 5 , 26s273. nordenskiold, a . e. 1863: geografisk och geognostisk beskrifn ing ofer nordostra delarne af spetsbergen och hinlopen strait. k. soenska vet. akad. handl. ny f d j d 4(7). 25 pp. nordenskiold, a. e. 1874: redogorelse for svenska polarek speditionen br 1872-1873. bilag k. svenska vet. akad. handl. 2(18). 132 pp. (printed 1875). olsson, i. u . , stenbera. a. & goksu. y. 1967: uoosalanatural 35, 197-207. olsson, i. u., shawky, e.-g. & goksu, y. 1969: uppsala natural radiocarbon measurements i x . radiocarbon 11, 515-544. parry, w. e. 1828: narrative f o r an attempt to reach the north pole. j . murray, london. 148 pp. pewb. t. l., rowan, d. e. & pcwc, r. h . 1982: glacial and periglacial geology of northwest blomesletta peninsula, spits bergen, svalbard. nor. polarinst. skr. 177. 32 pp, salvigsen, 0. 1978: holocene emergence and finds of pumice, whale bones, and driftwood at svartknausflya, nordaust landet. nor. polarinst. arbok 1977, 217-228. salvigsen, 0 . 1981: radiocarbon dated raised beaches in kong karls land, svalbard, and their consequences for the glacial history of the barents sea area. geogr. ann. 63a ( 3 4 ) , 283-291. salvigsen, 0 . 1984: two observations of pumice levels from the west coast of spitsbergen. polar research 2 , 115-116, this volume. schpt, v., hoppe, g., blake, w. jr & grosswald m. g. 1968: the extent of the w u m glaciation in the european arctic. assoc. int. d'hydr. sci. pub. 79, gen., assem. bern, 207-216. synge, f. m. 1980: a morphometric comparison of raised shorelines in fennoscandia, scotland and ireland. geol. radiocarbon measurements vii. radiocarbon-d, 454-470. foren. sthlm. forh. 102, 235-249. por_033.fm 126 polar research 26 2007 126 – 134 © 2007 the authors shausen sea and around peter i islandj. s. troncoso et al. quantitative analysis of soft-bottom molluscs in the bellingshausen sea and around peter i island jesús s. troncoso, 1 cristian aldea, 2 patrick arnaud, 3 ana ramos 4 & francisco garcía 5 1 departamento de ecología y biología animal, facultad de ciencias del mar, campus lagoas marcosende, 36310, universidad de vigo, spain 2 departamento de ecología y biología animal, universidad de vigo, spain, and fundación centro de estudios del cuaternario de fuego-patagonia y antártica (cequa), avenida bulnes 01890 – casilla 113-d, punta arenas, chile 3 le jas des batarins, 04110, vachères, france 4 ieo centro oceanográfico de vigo, cabo estai, vigo, spain 5 departamento de sistema fisicos, qvimicos y naturales, facultad de ciencias experimentales, universidad pablo de olavide, sevilla, spain. abstract macrobenthic soft-bottom molluscs were sampled in 30 stations located in the bellingshausen sea at depths ranging from 90 to 3304 m. the samples were collected using a quantitative grab box-corer during the cruises bentart 03, from 24 january to 3 march 2003, and bentart 06, from 2 january to 16 february 2006. molluscs represent 1074 specimens belonging to 62 species of polyplacophora, gastropoda, bivalvia and scaphopoda. the bivalve cyamiocardium denticulatum was the most abundant species (448 specimens). the abundance per station varied between 1 and 446 specimens. the shannon–wiener diversity index ranged between one specimen and 2.36, the pielou evenness index ranged between 0.00 and 1 and species richness ranged from 1 to 14 species. diversity showed great variations at different stations. after multivariate analysis (cluster analysis and nonmetrical multidimensional scaling) based on bray–curtis similarities, we were able to separate two principal clusters. the first cluster groups together species from shallower bottoms near peter i island and the antarctic peninsula, and the second cluster groups together species from deeper bottoms in the bellingshausen sea. the combination of environmental variables with the highest correlations with faunistic data was that of depth and coarse sand at the surface. keywords soft-bottom; molluscs; bellingshausen sea; peter i island. information about the benthic macrofauna of the bellingshausen sea and peter i øy (peter i island) was scarce. to date, approximately 895 species of gastropods and 379 species of bivalves are known from the southern ocean and adjacent regions (linse et al. 2006); clarke et al. (2004) mentioned approximately 530 species of gastropods and 110 of bivalves found exclusively in the southern ocean. only three families and 11 species were recorded in the bellingshausen sea, and two families and three species were recorded at peter i øy. this apparently low number of species is the result of poor sampling of this area: two samples on the continental shelf (1– 1000 m), none on the continental slope (1000–3000 m) and six deeper ( > 3000 m) have been obtained in the bellingshausen and amundsen seas out of 1490, 98 and 36 respective samples performed in these three zones in the whole southern ocean (clarke et al. 2004). the bentart 03 (from 24 january to 3 march 2003) and bentart 06 (from 2 january to 17 february 2006) research programs were carried out on board the rv hesperides in the bellingshausen sea and off peter i øy. benthic molluscs have a particularly wide ecological and ethological spectrum. so the assessment and analysis of their assemblages is likely to contribute to a better understanding of the structure and interactions inside the more complex benthic assemblages in which they live and interact. as an integrated study of the benthic ecosystem, the bentart programme is a good opportunity for analysing malacological assemblages. on the basis of the data obtained during this survey, we try to answer the correspondence jesús s. troncoso, departamento de ecología y biología animal, facultad de ciencias del mar, campus lagoas marcosende, 36310, universidad de vigo, spain. e-mail: troncoso@uvigo.es. doi:10.1111/j.1751-8369.2007.00033.x j. s. troncoso et al. quantitative analysis of soft-bottom molluscs in the bellingshausen sea and around peter i island polar research 26 2007 126 – 134 © 2007 the authors 127 following questions. is the molluscan fauna really poor in the bellingshausen sea and nearby areas? how many molluscan assemblages are living there? what are their species diversity and dominant species? what are their ecological characteristics or requirements? material and methods study area during the research cruises bentart 03 (january– february 2003) and bentart 06 (january–february 2006) molluscs were collected, together with other benthic invertebrates, at 40 stations in the bellingshausen sea, from the antarctic peninsula to thurston island on the border of the amundsen sea (fig. 1), at depths ranging from 90 to 3304 m (table 1). because of the weather conditions (big waves, heavy winds) the box-corer cannot work in all sampling stations, and for this reason only 30 stations were sampled and used in the present quantitative studies. sample collection in each station, the samples were collected using a quantitative grab box-corer (bc) with a maximum breakthrough of 60 cm and an effective surface of sampling of 25 × 25 cm. four samples were taken in each station. the first bc was used immediately after sampling to measure temperature, ph and redox (eh) at 6 and 25 cm below the surface of the sediment, and was subsampled later in the laboratory to analyse the sediment grain size, level of carbonates and content of organic matter. the three replica bc remaining were used to obtain the fauna. the content of each replica was sieved using three mesh sizes (5, 1 and 0.5 mm). the molluscan groups retained in the two largest sieves were counted to estimate their relative abundance in the total macrobenthic fauna. afterwards, the material was fixed in formalin and preserved in 70% ethanol for further taxonomic study. using the superficial layer of sediment, the following percentages of granulometric fractions were recorded: coarse sand, medium sand, fine sand and mud. carbonate content (%) was measured by treatment of the sample with hydrochloric acid, and the total organic matter content (om%) was estimated from the weight loss of the samples after 4 h at 450 ° c in an oven. data analysis data were organized into station by species matrices. univariate measures were calculated for each sampling fig. 1 study area and benthic sampling stations during the bentart cruises in 2003 and 2006. 128 polar research 26 2007 126 – 134 © 2007 the authors quantitative analysis of soft-bottom molluscs in the bellingshausen sea and around peter i island j. s. troncoso et al. station: total abundance ( n ), number of species ( s ), the shannon–wiener diversity index ( h ′ , log e ) and pielou’s evenness ( j ′ ). molluscan assemblages were determined through non-parametric multivariate techniques as described by field et al. (1982) using the primer v5.0 (plymouth routines in multivariate ecological research) software package (clarke & warwick 1994). a similarity matrix between sampling stations was constructed by means of the bray–curtis similarity coefficient by first applying fourth-root transformation on species abundance to downweight the contribution of the most abundant species. from this matrix, a classification of the stations was performed by cluster analysis based on the group-average sorting algorithm, as well as an ordination by means of nonmetrical multidimensional scaling (mds). possible differences in faunistic composition between the two major groups of stations were tested using a one-way anosim test. the simper program was then used to identify species that greatly contributed to the differentiation of station groups. the bio-env procedure was used to research the possible relationship between molluscan distributions in the bellingshausen sea and the measured environmental variables. the following variables were considered in this analysis: depth (m), redox (eh), om (%) and all granulometric fractions (%). carbonates were discarded from the analysis because of the lack of such data from bentart 03. all variables were previously transformed by log( x + 1). results abundance, number of species and diversity a total of 1074 molluscan specimens were collected belonging to 62 species in four classes. the bestrepresented class, in terms of number of species, was gastropoda (14 families and 33 species), followed by bivalvia (15 families and 25 species), scaphopoda (three families and three species) and polyplacophora (one table 1 location, depth and environmental parameters at the surface of sediments of survey stations: redox potential (mv), organic matter (om%), carbonates (%), gravel (% > 2 mm), coarse sand (% > 0.5 mm), medium sand (% > 0.25 mm), fine sand (% > 0.0625 mm) and mud (% < 0.0625 mm). station latitude s longitude w depth (m) redox om carbonates gravel coarse sand medium sand fine sand mud mb1 (2003) 70 ° 38.22 ′ 95 ° 15.36 ′ 534 252.2 4.81 n.d. 14.30 7.90 7.50 19.10 51.20 mb2 (2003) 70 ° 29.25 ′ 95 ° 14.83 ′ 780 289.3 5.02 n.d. 81.40 1.80 1.10 4.20 11.50 mb3 (2003) 70 ° 17.58 ′ 95 ° 11.86 ′ 1431 259.8 5.42 n.d. 29.00 4.30 3.40 30.50 32.80 mb4 (2003) 70 ° 52.86 ′ 98 ° 26.12 ′ 425 271.3 4.56 n.d. 31.00 9.60 5.40 16.40 37.60 pi 5 (2003) 68 ° 56.70 ′ 90 ° 35.70 ′ 126 199.3 1.43 n.d. 0.14 0.14 0.32 19.50 79.90 pi 6 (2003) 68 ° 49.61 ′ 90 ° 48.78 ′ 210 122.5 1.35 n.d. 0.00 0.10 0.10 21.00 78.80 pi 7 (2003) 68 ° 42.20 ′ 90 ° 40.80 ′ 410 174.8 1.85 n.d. 0.00 0.20 0.20 6.10 93.50 pi 8 (2003) 68 ° 50.18 ′ 90 ° 51.08 ′ 90 155.8 1.23 n.d. 0.10 0.80 4.90 58.90 35.30 mb9 (2003) 70 ° 14.40 ′ 81 ° 47.03 ′ 532 261.8 5.96 n.d. 3.90 6.10 4.40 12.40 73.20 mb10 (2003) 70 ° 44.31 ′ 81 ° 27.85 ′ 497 260 4.05 n.d. 15.80 5.20 7.90 16.40 54.70 mb11 (2003) 69 ° 27.07 ′ 82 ° 06.76 ′ 1289 266 3.81 n.d. 22.40 8.50 3.70 10.60 54.80 mb12 (2003) 69 ° 24.27 ′ 82 ° 11.88 ′ 2032 261.5 5.29 n.d. 23.00 11.10 5.80 18.06 42.04 mb13 (2003) 69 ° 49.56 ′ 77 ° 43.68 ′ 605 240.5 4.64 n.d. 10.20 3.60 4.10 17.50 64.60 mb14 (2003) 69 ° 21.12 ′ 78 ° 04.91 ′ 498 n.d. 3.68 n.d. 34.70 5.10 3.80 11.70 44.70 mb17 (2003) 68 ° 54.88 ′ 78 ° 14.16 ′ 2044 224.7 1.98 n.d. 64.50 18.60 3.90 2.90 10.10 pa21 (2003) 64 ° 54.01 ′ 63 ° 01.11 ′ 107 133.5 2.49 n.d. 4.40 14.80 17.90 34.80 28.10 pa22 (2003) 64 ° 50.58 ′ 62 ° 57.91 ′ 294 137 6.40 n.d. 0.00 0.00 0.30 3.20 96.50 pa23 (2003) 64 ° 55.95 ′ 63 ° 38.40 ′ 655 272.5 6.75 n.d. 0.00 0.50 0.50 7.10 91.90 pa24 (2003) 64 ° 20.11 ′ 61 ° 58.82 ′ 1056 170.5 8.32 n.d. 0.00 0.24 0.23 1.53 98.00 pa25 (2003) 63 ° 52.85 ′ 61 ° 48.52 ′ 110 n.d. 1.16 n.d. 23.80 22.90 13.50 36.30 3.50 mb26 (2006) 70 ° 14.62 ′ 95 ° 02.20 ′ 1920 178.9 1.99 5.87 1.33 11.22 29.09 49.43 8.94 mb29 (2006) 69 ° 26.08 ′ 88 ° 26.17 ′ 3304 262.1 8.92 1.14 1.54 5.56 2.47 5.25 85.19 mb30 (2006) 69 ° 58.98 ′ 87 ° 31.08 ′ 1814 187.7 7.01 2.97 58.38 1.78 1.02 8.88 29.95 mb31 (2006) 69 ° 56.98 ′ 86 ° 19.27 ′ 1426 207.8 5.31 2.54 0.00 2.22 4.81 20.74 72.22 mb33 (2006) 70 ° 15.90 ′ 84 ° 11.45 ′ 438 290.2 4.02 1.38 20.11 12.99 8.86 26.32 31.72 mb34 (2006) 70 ° 08.20 ′ 84 ° 51.68 ′ 603 326 1.80 1.27 0.00 12.91 14.98 59.89 12.21 mb35 (2006) 69 ° 56.03 ′ 85 °11.30′ 1117 260.7 7.36 2.40 47.65 3.78 1.73 9.13 37.72 mb36 (2006) 69°56.28′ 80°24.55′ 560 289 8.51 0.47 33.15 1.08 1.08 3.96 60.72 mb37 (2006) 69°26.38′ 80°51.62′ 495 244 5.70 0.64 35.37 17.04 10.27 16.15 21.17 mb38 (2006) 69°14.08′ 80°61.20′ 1324 298.2 5.98 0.83 65.69 3.14 1.26 2.72 27.20 mb, bellingshausen sea; n.d., not determined; pa, antarctic peninsula; pi, peter i øy. bentart 2003, january–february 2003; bentart 2006, january–february 2006. j. s. troncoso et al. quantitative analysis of soft-bottom molluscs in the bellingshausen sea and around peter i island polar research 26 2007 126 – 134 © 2007 the authors 129 table 2 systematic list of species found, indicating stations where these were collected. class/family species station polyplacophora leptochitonidae leptochiton kerguelenensis haddon, 1886 mb11, mb14, mb17, pa23 gastropoda anatomidae anatoma euglypta (pelseneer, 1903) mb31 trochidae antimargarita sp. mb37 calliotropis pelseneeri cernohorsky, 1977 mb4 calliotropis sp. mb30 margarella antarctica (lamy, 1905) pi8 solariella antarctica powell, 1958 mb11 submargarita notalis (strebel, 1908) pa21 family and one species) (table 2, fig. 2). the bivalves thyasira bongraini and cyamiocardium denticulatum accounted for 60% of all molluscs. the number of molluscs species per sampling site ranged from 1 to 14 (table 3). maximal abundances were found at sites pi5 (446) and pi8 (244), and the lowest were found at sites mb1, mb10, mb12 and mb17, with only one specimen in each. in mb26, mb29 and mb34, no molluscs species were obtained. the highest diversity was recorded at site pa21 (h′ = 2.36) in contrast to that found at mb9 (h′ = 0.27). j′ is usually high in sampling sites, except in stations near peter i øy. molluscan assemblages the cluster analysis (fig. 3) showed the presence of major groups of sites at a similarity level of 20%: group a (six shallow-water stations, 90–410 m in depth, high % of mud and low values of om) and group b (16 deepwater stations, 438–2044 m in depth, medium values of mud % and high om). mds ordination (fig. 4) showed similar results to those of the dendrogram, with an acceptable stress value (0.05). two major groups (a and b) are segregated from right to left, which can be identified as the depth gradient from shallow stations off peter i øy and the antarctic peninsula to deeper stations in the bellingshausen sea. the anosim test showed significant differences on the faunistic composition between groups a and b according to the depth factor: shallow (group a) vs. deep (group b) stations (global r = 0.571, p = 0.001). results of the simper analysis for the dissimilarity between groups are shown in table 4. the bivalves thyasira bongraini, cyamiocardium denticulatum, cuspidaria infelix, adacnarca nitens, cyclocardia astartoides, limopsis lilliei and the scaphopod siphonodentalium dalli f. antarcticus contributed greatly to the similarity (up to a cumulative 92%) in populations found for shallow-water stations of group a. the deeper-water of group b is mainly determined by dentalium majorinum. the species that contribute most to the dissimilarity between the two groups according to ratio values were t. bongraini, d. majorinum, c. infelix and c. denticulatum. relationship between biotic and environmental variables sediments were predominantly mud, with relatively high contents of organic matter (table 1). the superficial sediments appeared to be oxidized, as shown by redox (eh) values of greater than 122.5 mv. carbonate content was low in stations of bentart 06 (mb26, 29, 30, 31, 33, 34,fig. 2 number of species and specimens of each molluscan class. 130 polar research 26 2007 126 – 134 © 2007 the authors quantitative analysis of soft-bottom molluscs in the bellingshausen sea and around peter i island j. s. troncoso et al. zerotulidae dickdellia labioflecta (dell, 1990) pa22 eatoniellidae eatoniella glacialis (smith, 1907) pa21 rissoidae onoba gelida (smith, 1907) pi8, pa21 onoba kergueleni (smith, 1875) pi8 capulidae torellia planispira (smith, 1915) pa21 naticidae amauropsis anderssoni (strebel, 1906) pa25 amauropsis aureolutea (strebel, 1908) mb11 falsilunatia delicatula (smith, 1902) pi5, pi8 eulimidae balcis antarctica (strebel, 1908) mb13 muricidae trophon cuspidarioides powell, 1951 pi7 trophon drygalskii thiele, 1912 mb31 trophon longstaffi smith, 1907 pi5 buccinidae chlanidota signeyana powell, 1951 pi5, pi7, pa24 neobuccinum eatoni (smith, 1875) pi5 pareuthria regulus (watson, 1882) pi5 probuccinum costatum thiele, 1912 pi7 prosipho chordatus (strebel, 1908) pi8 prosipho hedleyi powell, 1958 pi8 volutidae harpovoluta charcoti (lamy, 1910) pa23 conidae belaturricula gaini (lamy, 1910) pa23 turridae leucosyrinx paratenoceras powell, 1951 mb36 lorabela sp. pi5, pi8 pleurotomella simillina thiele, 1912 pi7 typhlodaphne innocentia dell, 1990 pi5, pi8 acteonidae acteon antarcticus thiele, 1912 mb3 neactaeonina cf. edentula (watson, 1883) pi5 bivalvia nuculanidae propeleda longicaudata (thiele, 1912) pa21, mb33 yoldiidae yoldia eightsi (couthouy, 1839) pa22 yoldiella antarctica (thiele, 1912) pi7 yoldiella ecaudata (pelseneer, 1903) mb3, mb36 yoldiella oblonga (pelseneer, 1903) mb9, mb14 yoldiella profundorum (melvill & standen, 1912) pa22 malletiidae malletia pellucida thiele, 1912 mb31, mb35 arcidae bathyarca sinuata pelseneer, 1903 mb3, mb13, mb30, mb35, mb38 limopsidae limopsis lilliei smith, 1915 pa21, pa25 limopsis longipilosa pelseneer, 1903 mb33, mb37 philobryidae philobrya sublaevis (pelseneer, 1903) pi8 adacnarca nitens pelseneer, 1903 pi5, pi8, pa21 mytilidae dacrydium albidum pelseneer, 1903 mb38 limidae limatula simillina thiele, 1912 mb37 pectinidae adamussium colbecki (smith, 1902) mb2, mb3, pi5, pi7, mb30, mb31, mb35 thyasiridae thyasira bongraini (lamy, 1910) pi5, pi6, pi7, pi8, pa21, pa22, pa25 thyasira dearborni nicol, 1965 pa22 lasaeidae mysella antarctica (smith, 1907) pa22 pseudokellya cardiformis (smith, 1885) pa21 cyamiidae cyamiocardium denticulatum (smith, 1907) mb4, pi5, pi7, pi8, pa21 cyamiomactra laminifera (lamy, 1906) pi8 carditidae cyclocardia astartoides (martens, 1878) pa21, pa25 cyclocardia cf. intermedia thiele, 1912 mb4 thraciidae thracia meridionalis smith, 1885 pa21 cuspidariidae cuspidaria infelix thiele, 1912 pi5, pi7, pi8, pa21 scaphopoda dentaliidae dentalium majorinum mabille & rochebrune, 1891 mb1, mb2, pi7, mb9, mb10, mb13, mb14, mb31, mb33, mb35, mb36, mb38 rhabdidae rhabdus cf. perceptus (mabille & rochebrune, 1891) pi7, mb12 gadilidae siphonodentalium dalli f. antarcticus (odhner, 1931) pi5, pi6, pi7, pa24 class/family species station table 2 continued j. s. troncoso et al. quantitative analysis of soft-bottom molluscs in the bellingshausen sea and around peter i island polar research 26 2007 126 – 134 © 2007 the authors 131 35, 36, 37, 38 and 39). the depths in the sampling sites of the bellingshausen sea varied from 90 to 3304 metres. the anosim test also showed differences in faunistic composition among stations following a gradient of depth. the bio-env procedure (table 5) showed that the combination of environmental variables with the highest correlations with faunistic data was depth and coarse sand at the surface. redox (eh) and fine sand at the surface were not involved in the best combinations. depth was the variable with the best value when each variable was considered alone (pw = 0.390). discussion linse et al. (2006) divided the southern ocean into seven subregions based on richness hotspots of gastropods and bivalves: antarctic peninsula, weddell sea, three east antarctic subregions (dronning maud land, enderby land and wilkes land), ross sea, and the independent scotia arc and sub-antarctic islands, and excluded the west antarctic region (eights coast and the bellingshausen and amundsen seas), previously defined by clarke et al. (2004) from this classification because it is insufficiently studied. so, the present study, together with future more comprehensive faunistic studies (aldea & troncoso, unpubl. data), represents notable progress in the knowledge of the bellingshausen sea. for neighbouring areas, several surveys of semiquantitative (e.g. arnaud et al. 1998) and quantitative analyses of molluscan or macrobenthic fauna of the soft bottom have appeared in recent literature (e.g. sáiz-salinas et al. 1997; sahade et al. 1998; arnaud et al. 2001) showing distribution patterns and assemblages of several species, mainly from north-west of the antarctic peninsula. likewise, similar studies about the ross sea have previously been published (e.g. russo & gambi 1994; gambi et al. 1997). only one survey of the benthic marine fauna of table 3 faunistic parameters at each station: species richness (r), total abundante (n), pielou even ness index ( j′) and shannon–wiener diversity index calculated with the natural logarithm (h′), mo data (***). station richness (s) abundance (n) evenness (j′) diversity(h′) mb1 1 1 *** 0 mb2 2 2 1 0.69 mb3 4 5 0.96 1.33 mb4 3 3 1 1.10 pi5 14 446 0.40 1.06 pi6 2 145 0.72 0.50 pi7 12 67 0.58 1.45 pi8 14 244 0.49 1.29 mb9 2 13 0.39 0.27 mb10 1 1 *** 0 mb11 3 3 1 1.10 mb12 1 2 *** 0 mb13 3 3 1 1.10 mb14 3 7 0.87 0.96 mb17 1 1 *** 0 pa21 13 22 0.92 2.36 pa22 6 55 0.91 1.63 pa23 3 3 1 1.10 pa24 2 2 1 0.69 pa25 4 7 0.92 1.28 mb30 3 8 0.82 0.90 mb31 5 7 0.96 1.55 mb33 3 3 1 1.10 mb35 4 4 1 1.39 mb36 3 7 0.72 0.80 mb37 3 7 0.72 0.80 mb38 3 6 0.92 1.01 fig. 3 faunistic assemblages in the study are determined by cluster analysis based on braycurtis similarity. 132 polar research 26 2007 126 – 134 © 2007 the authors quantitative analysis of soft-bottom molluscs in the bellingshausen sea and around peter i island j. s. troncoso et al. table 4 results of simper analysis. species were ranked according to their average contribution to dissimilarity (contrib. %) between groups of stations. average abundance for each group (av. abund.), average dissimilarity (av. diss.), ratio value (dissimilarity/standard deviation, diss./sd) and percentage of cumulative dissimilarity (cum. %). groups b & a (average dissimilarity = 96.79) group b group a species av. abund. av. abund. av. diss. diss./sd contrib. % cum. % thyasira bongraini 0 2.36 16.46 1.54 17.01 17.01 dentalium majorinum 1.21 0.31 8.47 1.54 8.75 25.76 cyamiocardium denticulatum 0 1.64 7.17 1.12 7.41 33.17 siphonodentalium dalli f. antarcticus 0 0.86 6.72 0.67 6.94 40.11 cuspidaria infelix 0 1.03 4.74 1.36 4.9 45.01 cyclocardia astartoides 0 0.4 3.87 0.62 4 49.01 limopsis lilliei 0 0.33 3.26 0.62 3.37 52.38 amauropsis anderssoni 0 0.22 3.01 0.44 3.11 55.49 adacnarca nitens 0 0.65 2.9 0.98 2.99 58.48 adamussium colbecki 0.29 0.33 2.76 0.72 2.85 61.33 bathyarca sinuata 0.29 0 2.04 0.53 2.11 63.44 onoba gelida 0 0.39 1.86 0.7 1.92 65.37 chlanidota signeyana 0 0.36 1.75 0.67 1.81 67.18 falsilunatia delicatula 0 0.4 1.62 0.68 1.67 68.85 lorabela sp. 0 0.39 1.55 0.69 1.6 70.45 typhlodaphne innocentia 0 0.36 1.47 0.7 1.51 71.97 propeleda longicaudata 0.09 0.17 1.46 0.49 1.51 73.48 yoldiella oblonga 0.18 0 1.31 0.41 1.36 74.83 torellia planispira 0 0.22 1.27 0.44 1.32 76.15 thracia meridionalis 0 0.22 1.27 0.44 1.32 77.47 pleurotomella simillina 0 0.22 1.21 0.44 1.25 78.71 malletia pellucida 0.18 0 1.17 0.42 1.2 79.92 neactaeonina cf. edentula 0 0.26 1.03 0.44 1.07 80.99 submargarita notalis 0 0.17 0.97 0.44 1 81.99 eatoniella glacialis 0 0.17 0.97 0.44 1 82.99 pseudokellya cardiformis 0 0.17 0.97 0.44 1 83.99 philobrya sublaevis 0 0.24 0.96 0.44 0.99 84.98 trophon cuspidarioides 0 0.17 0.92 0.44 0.95 85.92 probuccinum costatum 0 0.17 0.92 0.44 0.95 86.87 yoldiella antarctica 0 0.17 0.92 0.44 0.95 87.82 rhabdus cf. perceptus 0 0.17 0.92 0.44 0.95 88.77 margarella antarctica 0 0.2 0.81 0.44 0.83 89.6 prosipho hedleyi 0 0.2 0.81 0.44 0.83 90.44 fig. 4 mds ordination of faunistic assemblages. the dotted line represents the separation of two main groups (a, b). the subgroups delimited with solid lines are derivates of cluster analysis. j. s. troncoso et al. quantitative analysis of soft-bottom molluscs in the bellingshausen sea and around peter i island polar research 26 2007 126 – 134 © 2007 the authors 133 the bellingshausen sea has been published previously (richardson & hedgpeth 1977). the main species recorded in the present survey are the same as those recorded during a similar survey in the south shetland islands and bransfield strait (arnaud et al. 2001): the tiny cyamiocardium denticulatum and thyasira bongraini, and the large dentalium majorinum, siphonodentalium dalli f. antarcticus, cuspidaria infelix and yoldia eightsi. mühlenhardt-siegel (1989) also found a high presence of t. bongraini. the same situation occurs in the ross sea, where cattaneo-vietti et al. (2000) found mainly the bivalves adamussium colbecki, galeommatidae undet., y. eightsi and t. dearborni (named as genaxinus debilis). molluscan assemblages exhibit a bathymetric pattern from deep-water stations (depth > 438 m) to shallowwater ones (depth < 410 m). deep-water stations with very low abundances (<13 specimens) mainly belong to group b, which is widely dominated by the large d. majorinum, followed by the bivalves a. colbeki, bathyarca sinuata and the tiny species limopsis longipilosa and the chiton leptochiton kerguelenensis. on the contrary, shallow-water stations with high abundances (22–446 specimens), belonging mainly to group a, and mostly located near the antarctic peninsula or peter i øy, are dominated by the tiny c. denticulatum and t. bongraini, followed by the larger scaphopod s. dalli f. antarcticus, c. infelix and y. eightsi. this result agrees with those of studies carried out in adjacent areas at depths generally shallower than 500 m, where arnaud et al. (2001) have reported the high presence and abundances of the bivalves c. denticulatum and t. bongraini. however, this result disagrees with the survey of cattaneo-vietti et al. (2000), who found mainly large bivalves (a. colbecki, y. eightsi) in depths of less than 380 m, and the tiny infaunal bivalve t. dearborni (under the name g. debilis) at depths of 222–1000 m. this is an inverse pattern, with tiny infaunal molluscs dominating at greater depths. in conclusion, the main molluscan species of the ross sea (schiaparelli et al. 2006), weddell sea (hain 1990) and the south shetland islands (arnaud et al. 2001) are also present in the bellingshausen sea, but in lesser abundance. peter i øy presents the highest values of abundances and number of species. t. bongraini and c. denticulatum contribute 60% of the total number of the specimens. depth and percentage of coarse sand could be the environmental variables that explain the distribution of molluscan assemblages in the bellingshausen sea. acknowledgements this research has been supported by the spanish government through the ministry of education and science. the officers and crew of the rv hesperides and our colleagues from the bentart cruises in 2003 and 2006 played a prominent part in the success of this project, and we express our gratitude to all of them. we are also grateful to juan moreira and two anonymous referees for their helpful comments that improved the manuscript. references arnaud p. m., lópez c.m., olaso i., ramil f., ramos-esplá a.a. & ramos a. 1998. semi-quantitative study of macrobenthic fauna in the region of the south shetland islands and the antarctic peninsula. polar biology 19, 160–166. arnaud p. m., troncoso j. s. & ramos a. 2001. species diversity and assemblages of macrobenthic mollusca from the south shetland islands and bransfield strait (antarctica). polar biology 24, 105–112. cattaneo-vietti r., chiantore m., schiaparelli s. & albertelli g. 2000. shallowand deep-water mollusc distribution at terra nova bay (ross sea, antarctica). polar biology 23, 173–182. clarke a., aronson r.b., crame j.a., gili j.m. & blake d.b. 2004. evolution and diversity of the benthic fauna of the southern ocean continental shelf. antarctic science 16, 559– 568. clarke k.r. & warwick, r.m. 1994. changes in marine communities: an approach to statistical analysis and interpretation. plymouth: natural environmental research council, plymouth marine laboratory. field j. g., clarke k.r. & warwick, r.m. 1982. a practical strategy for analysing multispecies distributions patterns. marine ecology progress series 8, 37–52. gambi m.c., castelli a. & guizzardi m. 1997. polychaete populations of the shallow soft bottoms off terra nova bay (ross sea, antarctica): distribution, diversity and biomass. polar biology 17, 199–210. hain s. 1990. die beschalten mollusken (gastropoda und bivalvia) des weddellmeeres, antarktis. (the shell-bearing table 5 best combinations of variables obtained through bio-env analysis according to the values of the spearman’s rank correlation (pw) for survey stations: depth (m), organic matter (om %), gravel (% > 2mm), coarses and (% > 0.5mm), mediums and (% > 0.25 mm) and mud (% < 0.0625 mm). number of variables correlation (pw) best variable combination 2 0.454 depth; coarse sand 3 0.410 depth; om; coarse sand 1 0.390 depth 3 0.385 depth; gravel; coarse sand 3 0.382 depth; coarse sand; mud 4 0.378 depth; om; coarse sand 3 0.378 depth; coarse sand; medium sand 4 0.368 depth; om; coarse sand; medium sand 4 0.362 depth; om; coarse sand; mud 3 0.359 depth; om; gravel 134 polar research 26 2007 126 – 134 © 2007 the authors quantitative analysis of soft-bottom molluscs in the bellingshausen sea and around peter i island j. s. troncoso et al. mollusca [gastropoda and bivalvia], weddell sea, antarctica.) berichte zur polarforschung 70, 1–181. linse k., griffiths h.j., barnes d.k.a. & clarke a. 2006. biodiversity and biogeography of antarctic and sub-antarctic mollusca. deep-sea research ii 53, 985–1008. mühlenhardt-siegel u. 1989. quantitative investigations of antarctic zoobenthos communities in winter (may/june) 1986 with special reference to the sediment structure. archiv für fischereiwissenschaft 39, 123–141. richardson m.d. & hedgpeth j.w. 1977. antarctic soft bottom, macrobenthic community adaptations to a cold, stable, highly productive glacially affected environment. in g.a. llano (ed.): adaptations within antarctic ecosystems. washington dc: the smithonian institution. russo g.f. & gambi m.c. 1994. first quantitative data on coastal soft bottoms populations off terra nova bay (ross sea, antarctica): bivalve molluscs. national scientific committee, antarctic oceanographic campaign 1989–90, data report (1994) ii. genoa: ministry of university, scientific and technological research. sahade r.j., tatian m., kowalke j., kühne s. & esnal g.b. 1998. benthic faunal associations on soft substrates at potter cove, king george island, antarctica. polar biology 19, 85–91. sáiz-salinas j.i., ramos a., garcía f.j., troncoso j.s., san martin g., sanz c. & palacin c. 1997. quantitative analysis of macrobenthic soft-bottom assemblages in south shetland waters (antarctica). polar biology 17, 393–400. schiaparelli s., lörz a. & cattaneo-vietti r. 2006. diversity and distribution of mollusc assemblages on the victoria land coast and the balleny islands, ross sea, antarctica. antarctic science 18, 615–631. por_021.fm 204 polar research 26 2007 204 © 2007 the author correspondence robert k. headland, scott polar research institute, lensfield road, cambridge cb2 1er, uk. e-mail: rkh10@hermes.cam.ac.uk. letter to the editor changes at peter i øy peter i øy, a remote norwegian territory, is one of the most rarely visited of the peri-antarctic islands. since the last norwegian research visit, in 1987, approximately 10 tourist ships have been to the island, and about half of these have made landings. where practical, reports have been sent to the norwegian polar institute and other interested parties. i have made five visits, landing during four of them, while employed by quark expeditions to lecture on antarctic history and geography aboard kapitan khlebnikov . my most recent visit, on 21 november 2006, demonstrated the continual geological erosion of the coast. in 2004 at pingvinholet there was a splendid triple natural arch: the outer arch was formed by black basaltic deposits, and the inner one was capped by a stratum of red oxidized larva. the third arch was the result of a basalt flake slipping and propping itself against the middle column. the sea penetrated through all three arches so that it would have been possible, although reckless, to take a small boat through the largest of them. in late 2006, while sailing from south america to new zealand near the antarctic coast, i noted the entire inner section had collapsed. only one large arch now remains and this no longer admits the sea. the collapse of both the cap of red larva and supporting pillar has formed a pile of rubble several metres above the sea. in the vicinity is framnæsodden, where the island was claimed for king haakon vii on 2 february 1929 and a hut was deployed. another was placed there on 10 february 1948. it was possible to examine the flatter portion of the hexagonal basaltic cape where the huts had stood, but no trace of either of the structures remains. landings were made on the steep beach just to the south of pingvinholet, where about 90 people went ashore for brief periods. the upper reaches of the site, which is the outer part of the pingvinholet arch, were occupied, as usual, by several chinstrap penguins ( pygoscelis antarctica ), and above that antarctic fulmars ( fulmaris glacialoides ) were abundant. during the visit several large boulders dropped from the vertical cliffs, and several large, freshly fallen, ones lay on the beach. the visitors kept well away from these cliffs. the natural arch, perhaps better described as a natural tunnel, owing to its length, at tsarsporten has remained unchanged since previous visits. the small beach immediately to its north is usually a haul-out for elephant seals ( mirounga leonina ). remains of the automatic meteorological station may still be seen on the sea stack tvistein. what remains of pingvinholet, photographed on 21 november 2006 (robert k. headland). late weichselian glaciation of the northern barents sea a discussion anders elverhoi a n d anders solheim elverhbi, a. & solheim, a. 1987: late weichselian glaciation of the northern barents sea a discussion. polar research 5 n s . , 285-287. anders elverhei and anders solheim, norsk polarimtitutt, box 158, n-1330 oslo lufthaun, norway. j= the holocene age of the raised beaches in eastern svalbard combined with the wide distribution of only a thin veneer of glacigenic sediments in the northern barents sea strongly indicate the existence of a late weichselian ice sheet in the region (salvigsen 1981; e l v e r h ~ i & solheim 1983; solheim et al. 1988) (figs. 1 & 2). however, the maximum extent of the ice sheet, the timing and pattern of deglaciation are still much debated. moraine ridges in the southwestern marginal parts of the barents sea may indicate a coalescence of the fenno scandian and svalbard/northern barents sea ice sheet cover ing the entire shelf (vorren & kristoffersen 1986). ridge complexes fringing the northern barents sea bank areas at 25& 300m water depth may represent a major stage during the retreat, or alternatively represent the maximum extent (elver hbi & solheim 1983). the unlithified sediments on the sea floor (fig. 1) are inter preted as a continuous sequence consisting of till overlain by proximal/iceberg dominated glaciomarine deposits, which grade into a distal glaciomarine facies representing the present day sea ice dominated environment (elverhbi & solheim 1983; solheim et al. 1988). laminated sediments may be present in the transition zone between the two glaciomarine units, in particular below 300m water depth. from extrapolation of the sedi mentation rate in the upper unit (based on datings of mainly astarte sp., fig. 2), the transition between the distal and the proximal/iceberg dominated glaciomarine deposits is tentatively dated to 1&12 ky b.p. the 10 ky is a minimum age based on findings of portlandia arctica with an age of 10,080 2 110 (south of nordaustlandet). accordingly, at 10 ky b.p. (at the latest) the late weichselian ice sheet had retreated to onshore posi tions with only minor outlet glaciers and iceberg production. the proximal/iceberg dominated facies, a unit suggested to be associated with the withdrawal of the late weichselian barents sea ice sheet, has not been dated. the unit is char acterized by a low content (1&1,000 individuals per 100 g sedi ment) of foraminifera. accelerator dating of foraminifera and calsispheres in two levels in a core from the central barents sea (figs. 1 & 2) shows reversed ages. 28 ka and 21 ka at 0.6 and 1.8 m sediment depth, respectively. (each sample was collected from a 40 cm interval of a 110 mm split core, and approximately 5 mg were dated.) due to the low microfossil content, a mixed assemblage had to be used, and the foraminifera showed clear evidences of abrasion. the dated samples are therefore inter preted as consisting of foraminifera of mixed ages. similarly, accelerator datings of foraminifera south of nordaustlandet (figs. 1 & 2) are, until more data are available, interpreted in the same way. the thickness of the proximal/iceberg dominated unit is in general %5 m, except for local accumulations ( e l v e r h ~ i & solheim 1983; solheim et al. 1988). a basic problem is to identify the onset of the proximal/iceberg glaciomarine sedi mentation, and thereby date the withdrawal of the grounded late weichselian ice sheet. the low content of foraminifera indicates a harsh environment cold water and a relatively rapid sedimentation rate. application of a rate of 100 cm/ka results in a depositional period of 3-5 ka. this, and also higher rates, are comparable to rates found in modem ice proximal regions (elverhbi et al. 1983; molnia 1983; powell 1984). according to such a depositional rate, the breakup of the northern barents sea ice sheet took place relatively early, 1% 17 ky b.p. indications of an early breakup may be found from the increased input of terrigeneous material corresponding to termination ia in sediment cores from framstretet and the eastern arctic ocean (knudsen 1985; zahn et al. 1985; thiede et al. in press). if this timing is correct, the deglaciation of the barents sea may have contributed significantly to the light isotope peak of termination i,, about 13 ky b.p. former reconstructions of the barents sea ice sheet have included the existence of extensive ice shelves, both for a maximum model with grounded ice t o the shelf edge (denton & hughes 1981) and for a more limited situation with grounded ice only on the banks in the northern regions (matishov 1984). the current data background is inadequate for a thorough discussion of ice shelves associated with the barents sea ice sheet. however, for the limited model, we consider at least large ice shelves unlikely as the barents sea is too shallow and without sufficient topographic relief providing the necessary anchor points. for the limited model the various troughs, e.g. bjbrnbyrenna and franz victoriarenna (fig. l ) , have acted as calving bays with sediment and iceberg supply from a grounded ice front. the 40-70 m thick glaciomarine accumulations in the inner parts of the troughs and along the slopes of the banks (elverhbi & solieim 1983; solheim et al. 1988) may represent the extensive sediment output during a recessional stage. in conclusion, the barents sea was most likely covered by grounded ice at least down to the present day 300 m contour (a limited model). the possibility that the northern barents sea ice sheet coalesced with the fennoscandian ice sheet and covered the entire barents sea to the shelf edge is still open to discussion. however, the timing of deglaciation is not known. 286 a . elverh@i & a . solheim 0 1 . 2 3 4 5 6 7 4 mud/pebbly mud "distal" glaciomarine / 7i:eck . pebbly mud "proximal" glacio marine sediments blue grey (late weichselian) based on the combination of datings and extrapolation of sedi mentations rates, 10 ky b.p. is regarded as a minimum age of the transition from a proximal/iceberg facies to the present day sea ice dominated sedimentary environment. estimation of sedimentation rates for the proximal facies may indicate degla ciation of the northern barents sea as early as w 1 7 k y b.p. the withdrawal of the barents sea ice sheet probably caused a significant support t o the light isotope influx at isotope stage 1, and to the increased clastic supply in framstretet and the eastern arctic basin during this interval, which is supposed to be about 13 ky b.p. stiff pebbly mud till (late weichselian) 5 1 0 m bedrock fig. 1. bathymetric map of the barents sea, including gener alized lithological description of the unlithified sediments in the northern barents sea. references denton, g . h. & hughes, t. j . 1981: the arctic ice sheet: an outrageous hypothesis. pp. 437-467 in denton. g. h. & hughes, t. j. (eds): the last great ice sheers. john wiley & sons. e l v e r h ~ i , a. & solheim. a. 1983: the barents sea ice sheet a sedimentological discussion. polar res. 1 n.s., 23-42. e l v e r h ~ i . a . . l m n e , 8. & seland. r. 1983: glaciomarine sedimentation in a modern fjord environment, spitsbergen. polar res. 1 n . s , 127-149. late weichselian glaciation of the northern bareiits sea a discussion 287 0.0 0.2 0.4 0.6 e 0.8 5 1 . 0 i e a 1.2 a 1.4 1.6 1.8 2.0 lithology c-age, years bp. 1 4 4 6 8 10 12 2 0 28 sedimentation rate: scm/ka i 12 t. distal glaciomarine (holocene1 0 a proximal glaciomarine sediments (late weichselian) distal glaciomarine sediments proximal glaciomarine sediments sample nr. 1-8, f m n e l v e r h i i i h solheim 1983. years bp a r e (in) nr. * fig. 2. i4c-datings and sedi 10 103 f o r m 10390t170 50-58 ua 301 mentation rate of late quat 12 280 forams/calc. 28080i1125 175-200 ua 304 ernary sediments in the northerr, barents sea. (dashed 11 280 f o r m 21203t825 45-70 ua 305 line: linear regression, locations port. arct. 10080i170 ua 302 * tan&m accelerator, university of gppsala, sweden. in fig. 1.) knudsen. b.-e. 1985: sen-kuarfrert paleomiljo i framstretet. unpubl. cand. scient. thesis. univ. of oslo. 74 pp. matishov, g . g . 1984: bottom of the ocean during glacial periods nauka, leningrad. 176 pp. (in russian). molnia, b. 1983: subarctic glacial-marine sedimcntation: a model. pp. 95-144 in molnia, b. (ed.): glacial-marine sedimentation. plenum press, ny. powell, r . d . 1984: glaciomarine processes and inductive litho facies modelling of ice shelf and tidewater glacier sediments based on quaternary examples. marine geol. 57, 1-52. salvigsen, 0. 1981: radiocarbon dated raised beaches in kong karls land, svalbard, and their consequences for the glacial history of the barents sea area. geogr. ann. 63a, 283 291. solheim, a , , miltiman, j . d . & elverhei, a. 1988: sediment distribution and sea floor morphology of storbanken; impli cations for the glacial history of the northern barents sea. canadian journal of earth sciences (in press). thiede, j., clark, d. l. & herman, y . 1988: late mesozoic and cenozoic paleoceanography of northern polar oceans. in grantz, a . , johnson, l. & sweeny, w. (eds.): dnagarctic vol. (in press). vorren, t. 0. & kristoffersen, y. 1986: late quaternary glaciation in the south-western barents sea. boreas i s . 51 59. zahn, r., markussen, b. & thiede, j. 1985: stable isotope data and depositional environment in the late quaternary arctic ocean. nature 314. 433-435. additional rb-sr and single-grain zircon datings of caledonian granitoid rocks from albert i land, northwest spitsbergen ju. a. balasov, j . j. peucat, a. m. teben’kov, y. ohta, a. n. larionov and a. n. sirotkin balasov, ju. a,, peucat, j . j., teben’kov, a. m., ohta, y., larionov, a. n. & sirotkin, a. n. 1996: additional rb-sr and single-grain zircon datings of caledonian granitoid rocks from albert i land, northwest spitsbergen. polar research 15(2), 153-165. previous k-ar and rb-sr datings of the metamorphic and granitic rocks from the northwestern basement region of spitsbergen mainly show the cooling time of the rocks, except for a rb-sr isochron age of the hornemantoppen granitoid. new samples were collected during several years of geological mapping in the area and the rb-sr whole rock isochron and single-grain zircon evaporation methods were applied to the hornemantoppen granitoids and the grey granites. a dioritic dyke was also dated by the latter method. the bulk rock chemistry study shows that most of both granitic rocks are of the s-type and probably post orogenic, with distinctive incorporation of crustal materials. the isotopic data also support this interpretation. the results of the rb-sr isotope analyses, 412 2 4.8 ma and the zircon pb evaporation age of 424 2 56 ma, confirm the previous age of the hornemantoppen granitoid, 414 2 10 ma. an older zircon age of 547 2 19 ma is considered to be the minimum age of inherited zircon. zircons from the grey granites suggest an age of ca. 420 ma with a large error. field relations demonstrate that the grey granites are older than the hornemantoppen granitoids. a minimum inherited zircon age, 952 t 20 ma, has been obtained from the grey granites. three multi-grain pb ages, 423 ? 22ma (2 grains), 461 2 42ma and 561 2 93 ma (the last two 3 grains) were considered to be mixed ages. although no definitive evidence for the presence of grenvillian granites in this area has been obtained in the present study, preliminary results from the multi-grain zircon evaporation method, carried out in the russian laboratory at apatity, infer paleoand mesoproterozoic protoliths for the metamorphic rocks of northwestern spitsbergen. ju. a. balabv and a. n. larionov, geological institute of kola science centre, al. fersman 14, 184200 apatity, russia; j . j . peucat, laboratoire de gtochimie et de giochronologie, gtosciences-rennes, f 35042 rennes cedex, france; a. m. teben’kov and a. n . sirotkin, polar marine geologic expedition, ul. pobedy 24, 189510 lomonosov-st. petersburg, russia; y. ohta, norsk pvlarinstitutt, p.o. box 5072 majorstua, n-0301 oslo, norway. introduction three types of granitic rocks have been known for a long time (e.g., darocher in gaimard 1855; blomstrand 1864; schetelig 1912; schenk 1937) in the northwestern part of spitsbergen, north of kongsfjorden and west of raudfjorden-monacob reen, within a widely developed gneiss-migmatite region (hoe1 1914; holtedahl 1926; orvin 1940; gee & hjelle 1966; krasil’seikov 1973; hjelle 1974, 1979; ohta 1969, 1974a, b; abakumov 1976a, 1976b, 1979; ravich 1979; hjelle & lauritzen 1982) (fig. 1). the schists, gneisses and migmatites, primarily precambrian, in this area have been divided lithostratigraphically into three units by gee & hjelle (1966): the generalfjella formation, ca. 2 km in thickness, of marble and various schists; the signehamna formation, ca. 2-2.5 km in thickness, of thick schists and gneisses derived mainly from areno-argillaceous protoliths with some quart zites; and the nissenfjella formation, ca, 1.7 km in thickness, of various gneisses and migmatites including amphibolites. abakumov (1976b, 1979) made another divi sion: the smeerenburgfjorden series of gneisses and migmatites, corresponding to the migmatitic parts of the nissenfjella formation of gee & hjelle (19661, which is subdivided into the waggonwaybreen suite and the kollerbreen suite, and the krossfjorden series which includes the rest of the lithostratigraphy of gee & hjelle. both authors distinguished the post-orogenic horne mantoppen granitoids which cut the gneisses and migmatites. the metamorphic and migmatitic rocks have 154 ju. a . balasov et al. additional rb-sr and single-grain zircon datings of caledonian granitoid rocks 155 recorded a complex deformation history in their structures (hjelle 1974; ohta 1969, 1974a) and the young enveloping fold structures of caledo nian in age are large scale asymmetric open antiform and synform, probably westwards of vergence, the axes of which plunge gently to the south, with the deeper rocks exposed in the north (gee & hjelle 1966; hjelle 1979). detailed petrological studies on the marbles by bucher nurminen (1981) and pelitic gneisses by klaper (1986) showed that the highest metamorphic conditions were 4-6 kb and 600-700°c. ohta (1974b) also obtained 5.5 kb and 650-700°c. based on the occurrences of relict kyanite and staurolite, the latter mineral inferred from clusters of a corundum-spinel-cordierite-biotite assem blage (ohta 1974a), it was considered that the prograde process of metamorphism was of the intermediate-pressure facies series, which was superimposed by high-temperature series reac tions (ohta 1974a; klaper 1986). four main types of granitoid rocks have recently been recognised in this area: (1) con cordant layers and veins of foliated granitic-aplitic rocks and the neozomes of the migmatites; (2) gneissose granites containing strongly stretched gneiss-quartzite inclusions; (3) unfoliated grey granites, locally discordant to the schists, gneisses and migmatites; and (4) a batholith of massive, pink-coloured granitoid rocks, intruding all three types mentioned above. in addition there are various small dykes cutting the gneiss-migmatites. the bulk rock composition and texture of type (1) granitic rocks show gradational transitions both to the migmatite neozomes and to type (3) grey granites (hjelle 1974; ohta 1969, 1974a, b). type (4) hornemantoppen granitoids are petro graphically biotite-bearing monzonogranites and granites (streckeisen 1976) with or without hornblende (hjelle 1974). these three granitoid rocks mentioned above have been known before. type (2) gneissose granites, newly distinguished, have not been studied chemically, while field evidence shows that they are intruded by the grey granites. numerous small dykes and veins of granitic, dioritic, aplitic and pegmatitic compositions occur in this area, type ( 5 ) , in addition to the main granitoid rocks. some of the dykes and veins cut the gneiss-migmatites and various granitoid rocks, while some others were deformed together with the host rocks, showing different stages of emplacement. petrography of the analysed samples the dated grey granites and hornemantoppen granitoids were analysed together with some additional samples from scattered localities for their bulk rock chemical compositions, at the chemical laboratory of kola science center in apatity, russia. grey granites samples 15-1-15-5 are grey granites from various localities over a wide area, as shown in fig. 1. samples spz-3 and spz-4, used for zircon dating, are from the same locality as 15-1. the grey granite bodies have mostly concor dant, locally discordant, but sharp contacts to the gneiss-migmatites, and the shapes of these bodies are slightly oblique to the structure of the surrounding rocks. the rocks are heterogenous biotite-bearing granodiorite to granite in composi tion and locally have plagioclase phenocrysts up to 3 cm in length. rare seams of dark gneissic materials are included. sample 15-1 is a coarse-grained biotite granite, having cataclastic texture, containing plagioclase and quartz, both 30%, and k-feldspar and biotite, each about 10%. a few grains of amphibole are also recognised. secondary chlorite, sericite and zoisite occupy about 15%. zircon, apatite and barite are accessory minerals. samples 15-2, 15-3 and 15-5 are similar to one another and contain 15% k-feldspar, as much as 40% plagioclase (anl5), 30% quartz, 10% biotite and 5% hornblende. zircon, apatite, orthite and sphene are accessories and biotite is locally chloritised. the rocks have a medium-grained, massive mosaic texture. sample 15-4 is a medium-grained biotite granite, having 30% each of k-feldspar, quartz and plagioclase ( a n z o ) and about 10% biotite. the fig. 1 . distribution of the granitoid rocks in northwestern spitsbergen, with the locations of the analysed samples. key: black = grey granites; cross-lined = hornemantoppen granitoids; dotted areas = schists, gneisses and migmatites; open areas = glaciers; bloken curve = fault. 156 ju. a . balasov et al. biotite is completely converted into chlorite and accessories are zircon, apatite, orthite and sphene. hornemantoppen granitoids the dated samples 14-2-14-8 are from various localities in the hornemantoppen granitoid massif (fig. 1). these granitoid rocks cut the grey granites and gneiss-migmatites and locally con tain angular xenoliths of gneiss-migmatites. sample 14-1 is from the northern coast of bj~rnfjorden and is a pink coloured, mediumto coarse-grained rock, similar to the horneman toppen granitoids. however, the clearly recogni sable boundary between the grey granites and the hornemantoppen granitoids has been observed about 2 km east of this locality along the northern margin of smeerenburgbreen. the rocks near the northern boundary of the hornemantoppen gran itoid massif around the locality of sample 14-1 are apparently similar and difficult to discriminate from the grey granites in the field. sample 14-1 is considered as belonging to the homemantoppen granitoids in this article because of its pink colour, but it may be a mixture of the two granitoid rocks. sample s p z j , used for the single-grain zircon dating, was collected from the same locality as samples 14-3 and 14-5 are biotite granites similar to 14-1, with 50 modal % k-feldspar, 20% plagioclase ( a i i ~ s a ~ ~ ~ ) , 20% quartz and about 10% biotite. samples 14-1 and 14-5 have trace amounts of hornblende. magnetite, apatite, sphene, zircon and monazite are common acces sories and ilmenite is included in biotite. chlor itisation of mafic minerals and sericitisation of plagioclase with epidote-zoisite grains are often seen. sample 14-2 is a medium-grained, hornblende biotite granite, with k-feldspar, zoned plagioclase (anz-an30 in the core and anlo-anzo at the margin) and quartz equally at 30%, and 10% mafic minerals. sphene, zircon, apatite and magnetite are accessories. 14-4 is similar to 14 2, but has no hornblende. sample 14-6 is a fine-grained, biotite aplitic rock with 60% k-feldspar, 18-19% plagiocla se(an15), 20% quartz and 1-2% biotite. apatite, sphene and hornblende are accessories and biotite is often chloritised. 14-7 is a fine-grained, two-mica aplitic rock, with similar colour as the hornemantoppen granitoids, having equal amounts (ca. 45%) of 14-1. k-feldspar and plagioclase (an,,), 10% quartz and small amounts of micas. this sample was collected from a dyke cutting the gneiss-migma tites outside the hornemantoppen granitoid massif to the south; therefore, it is incorporated in the chemical discussion, but not dated. sample 14-8 is a pale pink, fine-grained aplitic rock, consisting of roughly equal amounts (30%) of k-feldspar, plagioclase and quartz, with about 10% of biotite and muscovite aggregates. musco vite exceeds biotite. the accessories are pyrite, apatite, zircon and magnetite. the magnetite grains are sometimes coated by hematite. sec ondary minerals are not common, except for rare conversion of biotite into chlorite. dioritic dyke sample 16-1, dated by zircon, is a dioritic dyke cutting the migmatites on amsterdamaya (fig. 1). dykes of similar composition cut the grey granites at many localities. other rocks not dated samples 20-1-20-3, which were not analysed isotopically, are from the grey granites to the south of the hornemantoppen granitoid massif and were analysed for supplementary data of the bulk rock chemistry. sample 20-1 is a medium grained biotite granite containing roughly 30% each of k-feldspar, plagioclase ( a n ~ , + n ~ ~ ) and quartz and 10% biotite. magnetite, zircon apatite, fluorite and monazite are accessories. secondary sericite occurs in k-feldsper and plagioclase grains are dusty with calcite and chlorite. sample 20-2 lacks k-feldspar and is a quartz diorite. sample 20-3 is similar to 20-1, but has as much as 40% of k-feldspar and about 20% of quartz. petrochemistry major element analyses of the rocks are shown in table 1. the compositions of spz-3 and spz-4 are represented by that of 15-1, and spz-5 by 14 1. the analysed samples are granite, monzono granite and granodiorite on the q-p diagram (fig. 2) (debon & le fort 1983). a trend of slightly higher p-values (k20 contents) for the grey granites compared to the hornemantoppen gran additional rb-sr and single-grain zircon datings of caledonian granitoid rocks 157 table 1 . major element analyses of the granitoid rocks. sample si02 tioz n203 fe203 feo mno mgo cao nazo kzo pz05 s h 2 0 total 14-1 14-2 14-3 14-4 14-5 14-6 14-7 14-8 15-1 15-2 15-3 15-4 15-5 16-1 201 20-2 20-3 65.91 70.69 74.07 70.65 64.61 75.57 75.21 78.00 69.83 69.13 67.80 72.03 67.01 55.05 67.52 71.56 72.22 0.74 15.70 0.84 3.71 0.07 1.68 3.82 3.38 0.41 14.00 1.32 1.85 0.06 0.70 2.78 3.30 0.15 14.41 0.40 1.31 0.06 0.20 0.58 3.75 0.41 14.38 0.80 2.03 0.05 0.70 2.42 3.62 0.60 16.31 0.98 3.17 0.05 1.60 3.60 3.84 0.06 13.40 0.32 0.95 0.04 0.10 0.53 3.46 0.03 15.82 0.25 0.77 0.04 0.10 0.33 4.70 0.05 12.29 0.11 1.07 0.05 0.10 0.30 3.80 0.66 15.11 0.58 3.23 0.06 0.99 1.85 3.55 0.52 15.00 0.88 2.99 0.05 0.55 2.23 3.86 0.55 15.21 0.46 3.59 0.09 1.02 2.84 4.03 0.27 13.90 0.09 2.27 0.08 0.55 1.99 3.09 0.62 14.92 0.31 4.07 0.06 1.41 2.41 3.38 1.31 17.44 3.65 4.61 0.08 4.98 7.38 2.50 0.75 15.10 0.12 5.02 0.07 1.66 1.80 2.60 0.41 14.53 0.21 2.51 0.04 0.84 2.01 2.40 0.40 14.59 0.26 2.45 0.03 0.40 1.51 3.20 3.20 4.12 4.15 4.32 3.48 4.96 3.91 4.00 4.21 4.44 4.08 4.28 4.16 1.46 3.50 4.91 5.09 0.18 0.08 0.05 0.07 0.19 0.05 0.05 0.05 0.11 0.06 0.12 0.0s 0.23 0.32 0.14 0.09 0.15 0.05 0.98 0.60 0.80 0.54 0.76 0.02 0.38 0.32 0.05 1.06 0.05 0.94 0.42 1.20 1.12 0.02 1.80 1.46 0.46 0.48 100.26 99.91 99.93 99.99 99.19 99.46 101.59 100.14 101.29 100.70 100.21 99.80 99.70 100.60 99.74 99.97 100.78 itoids is seen in this diagram. however, the grey granites have a wide variation of k20 contents (ohta 1974b, fig. 7) and this high k20 tendency is only recognisable within the rocks analysed in this study. the high kzo (3.2-4.9 wt%) and relatively low nazo contents (lower than 4.7 wt%) indicate that all rocks are s-type granites (chappel & white 1974). most rocks plot along the eutectic valley between the albite and k-feldspar fields at various h 2 0 pressures on the normative q-ab-or diagram (fig. 3a). all samples are calcalkaline on the afm diagram (fig. 3b), and belong to the high-k series (fig. 4a) (ewart 1976). the alkali-lime index is ca. 59 on the total alkalis-sioz diagram (fig. 4b). on the sand’s diagram (fig. 5a) the majority of the analysed samples are peralumi nous and plot in the cag (continental arc granitoids) and ccg (continental collision gran itoids) fields of maniar & piccoli (1989). some rocks which plot in the metaluminous field contain various amounts of hornblende. the grey granites show a positive relation between the two ratios of this diagram, while the homemantoppen granitoids show a slightly negative trend. this difference is possibly caused by the hornblende contents in the latter. referring to various diagrams proposed by maniar & piccoli (1989), both types of granitic rocks fit with the fields of pog and iag+ cag + ccg on the n203 vs. s i 0 2 (fig. 5b), and with the fields of pog on the feo* vs. mgo (fig. 6a), feo* + mgo vs. cao (fig. 6b) and feo*/ (feo* + mgo) vs. si02 (not shown in this article) diagrams. in fig. 6b, the grey granites show a slightly negative trend, while the horneman toppen granitoids have a weak positive trend. t / , l o -150 -100 -50 0 p = k-(na+ca) fig. 2. chemical classification of the analysed rocks on the q-p diagram of debon & le fort (1983). legend (common for figs. 2 4 ) : solid circles = grey granites; open circles = homeman toppen granitoids. 158 ju. a. balasov et al. q l ‘t a i i r i ab c30 50 70or b fig. 3. felsic and mafic ratios of the rocks. a: normative q ab-or diagram. solid curves are eutectic valleys at various h20 pressures. b: afm diagram. solid curve: division of tholeiite and calcalkalic rocks (irvine & baragar 1971). this is due to the larger amounts of hornblende in the latter, the same reason as in fig. 5a. although there are slight differences between the grey granites and the hornemantoppen granitoids in their bulk rock chemistry, the two types of granitoids have nearly the same composi tion and belong to similar differentiation trends typical for post-tectonic granitoids in their later stage. previous isotopic dating the gneisses and migmatites in northwestern spitsbergen have been considered as caledonian products since the time of holtedahl (1926). however, krasil’scikov (1973) and abakumov (1976b, 1979) proposed that these rocks were the basement to the caledonian rocks and are paleoproterozoic karelian basement reworked by caledonian tectonothermal events. k-ar whole rock and biotite ages from this area were summarised by gayer et al. (1966) and mainly fall in the range of 380-450 ma, with the estimated main thermal event at around 430 ma. the k-ar biotite ages are around 400 ma, and these ages and k-ar whole rock ages in the range of 375-340 ma are considered to be cooling ages. a rb-sr whole rock isochron age of the hornemantoppen granite has been reported by hjelle (1979) at 414 t 10 ma. ravich (1979) additional rb-sr and single-grain zircon datings of caledonian granitoid rocks 159 fig. 4. alkali contents of the rocks. a k 2 0 vs. so2 diagram. division lines, ewart (1976). b: total alkalis and cao vs. s o 2 diagram. circles = k 2 0 . triangles = cao. fig. 5. alzo,-contents of the rocks: a: al-saturation of the rocks. a = al, n = na, k = k, c = ca. cag = continental arc granitoids, pog = post orogenic granitoids, ccg = continental collision granitoids, iag = island arc granitoids (maniar & piccoli 1989). b: al vs. s i 0 2 diagram. classification by maniar & piccoli (1989). rrg = rift related granitoids, ceug = continental epeirogenic uplift granitoids. other abbreviations are the same as fig. 5a. 5 8 0 shoshonitic calcalkalic 1 low-k 1 60 65 70 75 80 siol wt % 0.4 o m 9 r l 0.9 1.0 1.1 1.2 1.3 1.4 n c n k iag+cag+ccg s o . . ' o0 *\ 160 ju. a. balaiov et al. s o l 6 u 4 4 0 c 3 0 c ." 0, f 2 0 10 o . ;; 20 n b rrg+ceug 0 fig. 6. fe* (total fe), mg and ca contents of the rocks. abbreviations are the same as for figs. 5a and b (maniar & iag+cag+ccg i i piccoli 1989). a: feo" vs. -iac+cac+ccg made two additional k-ar whole rock datings on a gneiss and a leuco-granite from the north of kongsfjorden, which gave ages of 430 and 380 ma, respectively. new datings rb-sr dating five samples of the grey granites, 15-1 to 15-5, and seven samples of the hornemantoppen granitoids, 14-1 to 14-6 and 14-8, were analysed by the whole rock rb-sr method. analytical method. -the whole rock samples were dissolved in hf and hc104 and residue was dissolved in hcl and put in a column with dowex 50 x 3 (200-400 mesh) resin. the sr isotope compositions were determined by the mi 1201-t mass-spectrometer at the laboratory of kola science centre, apatity, russia. rb and sr blanks were 2 ng and 8 ng, respectively. rb and sr contents were determined by the xrf method. analytical errors (2 sigma) are assumed to be 1.5% for 87rb/86sr and 0.04% for 87sr/86sr. the age calculation was carried out using the program of ludwig (1991). table 2. rb and sr isotope compositions. from the left to right: column 1, sample no.: columns 2 and 3, rb and sr contents in ppm.; column 5, 1.5% error; column 6, normalised to *%rp8sr = 0.1194; column 7, 2 sigma error in the last degits. sample nos. 4= hornemantoppen granitoids; nos. 5= grey granites. rb sr no. ppm ppm r7rb/rhsr error r7srf"sr error 14-1 107 14-2 149 14-3 161 14-4 162 14-5 168 14-6 168 14-8 246 15-1 165 15-2 227 15-3 236 15-4 184 15-5 132 462 293 97 278 44 44 18 168 196 332 166 498 0.684 1.412 4.653 1.621 0.923 10.525 10.561 2.727 3.221 1.982 3.091 0.740 0.010 0.71251 0.021 0.71655 0.070 0.73573 0.024 0.71741 0.014 0.71477 0.158 0.77035 0.158 0.77045 0.040 0.73669 0.048 0.73116 0.030 0.71943 0.046 0.74486 0.011 0.71221 10 10 13 16 9 9 20 15 13 8 12 10 additional rb-sr and single-grain zircon datings of caledonian granitoid rocks 161 0.75 0.74 0.73 in l '9 w tn 0.72 0.71 0.70 0 412.7 +/-4.8 ma k mswd = 0.43 . ir = 0.7084+/-2 * m l cn m i. 0.74 0.70 ' 1 " ' 1 1 ' 1 ' ' 0 2 4 6 8 10 12 8 7 r b p 6 s r i i i i 4 15-4q b min. 436 ma (n=2) . ir=0.708 l 15-10 1 5 2 0 15-3 # 0 o 0 , 0 0 . 15-2 o* 7 , i i i 1 2 3 fig. 7. rb/sr isotope diagrams. a hornernantoppen granitoids. samples in parenthesis have been excluded from the age calculation. b: grey granites. results. seven samples of the hornemantoppen granitoids from various localities within the massif (fig. 1) and five samples of the grey granites from widely separated localities were analysed and the results are shown in table 2. the age from all seven samples of the hornemantoppen granitoids is 419 2 11 ma and mswd is 4.43. five samples excluding 14-2 and 14-4 provide a good isochron, giving an age of 413 5 5 ma with mswd = 0.43, and the initial 87sr/86sr ratio = 0.7084 2 2 (fig. 7a). sample 14 2 is slightly higher and 14-4 is slightly lower than the isochron for unknown reason and have been excluded from calculation. the rb-sr isotopic results of the grey granites scatter widely and do not show any isochron (fig. 7b). a line through points 15-3 and 15-5 only corresponds to an age of 436 ma. singleand multi-grain zircon ages two grey granite samples, spz-3 and spz-4, one hornemantoppen granitoid and one dioritic dyke rock, were analysed by the singleand multi-grain pb evaporation method. analytical method. the separated zircon grains were analysed by the pb evaporation method described by kober (1986) at the isotope chem istry laboratory of the university of rennes, france, using the cameca tsn 206 mass spectro meter. correction for mass fractionation was 0.10% per amu, following analyses of the nbs 981 and 983 standards. the common lead used for the correction had an isotopic composition corresponding to an age of 1,150 ma, following the two-stage model of stacey & kramers (1975). two steps of evaporation were made for each sample. results. the analytical results are shown in table 3 and figs. 8a-8e. sample spz-5 is tentatively considered to be a hornemantoppen granitoid as mentioned for 14-1. this is not typical hornemantoppen granitoids, however, it was only possible to collect a sample from this locality when we visited in 1985. three morpho types of zircon have been found in this rock: (1) elongated, euhedral grains having an overgrowth of an orange-pink coloured margin around a round core; (2) orange-transparent, euhedral crystals, similar to the overgrowth of morphotype 1, but without a core; and (3) round, orange-coloured crystals similar to the overgrowth of morphotype 1. morphotypes 1 and 3 were analysed, the former provided a 207pb/206pb age of 547 2 19 ma (fig. 8a) and the latter gave a age of 424 2 56 ma (table 3; not shown in fig. 8 because of large errors). sample spz-4 is a sample from the grey 162 ju. a. balasov et al. table 3. pb isotope analyses. column 2 from the left: first numbers are the number of analysis. two-lettered abbreviations: eh = euhedral = st, stocky = el, elongated, or = orange, br = brown, yl = yellow, tr = transparent. analysis, sample zircon step (ampere) spz-3 1: eh,el,yl,tr 2 eh 3: eh spz-4 1: eh,st,br,tr spz-5 1: eh,el,or,tr 2 eh,el,or,tr 16-1 1: eh,br 2.7 2.7 2.8 2.9 2.8 2.8 2.6 206pb/z04pb (measured) 676 est. 3000 9123 2020 5422 583 16428 z07pb/z06pb (measured) 0.0799 0.0598 0.0577 0.078 0.0612 0.0799 0.0563 ~~ error 207pb/206pb age, ma. error (2 sigma) (corrected) (207pb/206pb) (2 sigma) 10 0.0589 561 62 3 0.0553 423 11 4 0.0562 461 17 2 0.0708 952 7 2 0.0585 547 9 8 0.0553 424 40 3 0.0552 421 15 2: eh,br 2.8 23000 0.0556 17 (not calculated) granites and the analysed zircon is a brown coloured, stocky euhedral crystal, rich in inclu sions and with a large core visible. the lead isotope age recorded is 952 2 20 ma (fig. 8b). sample spz-3 is a grey granite and has zircons with yellow-transparent, euhedral shape, fre quently having small, irregularly zoned cores. due to the small size of the grains, several grains were used: one analysis with 2 grains and two analyses with 3 grains. the 2-grain analysis yielded an age of 423 2 22 ma (fig. 8d), while the 3-grain analyses gave ages of 461 ? 42ma (fig. 8c) and 561 ? 93 ma (table 3). sample 16-1 is a dioritic dyke rock. analysis of one zircon gave an age of 421 f 36 ma (fig. 8e). interpretation of the obtained ages hornemantoppen granitoids the rb-sr age, 413 f 5 ma, shows a good agreement with the previously reported rb-sr age, 414 f 10 ma (hjelle 1979). sample spz-5, a pink granite which was collected as a representative of the hornemantop pen granitoids in the field, yielded two zircon ages, the younger one being 424 2 56 ma, which is in agreement with the rb-sr isochron age. the older age obtained from a non-transparent single zircon grain of spz-5, 547 2 19 ma is considered to correspond to the minimum age of inherited zircon. the high 87sr/s6sr initial ratio, 0.708, and the existence of a core in the zircon grain, indicate the incorporation of old crustal material during the formation of this granite. grey granites the rb-sr data scatter widely. calculations back to 450 ma yielded initial 87sr/86sr ratios ranging from 0.707 to 0.725, suggesting crustal contribu tions in the genesis of these rocks. the oldest single grain zircon age, 952 f 20 ma, is interpreted to be an inherited zircon age. the old ages obtained by the 3-grain analyses of spz-3, 561 ma and 461ma are uncertain with errors of ? 93 ma and 2 42 ma, respectively. however, they also suggest the existence of some inherited material. the 2-grain age of spz-3, 423 2 22ma is considered to be less contami nated by inherited lead and thus closer to the crystallisation age of the zircon. the younger age obtained from spz-5, as well as the age obtained on the granodiorite dyke 16-1, are similar to this age, though both have large errors. discussion other preliminary studies of zircons have been carried out by the multi-grain pb evaporation method at the laboratory of kola science centre in apatity, russia, from the late 1980s, and the results were summarised by teben'kov in 1993 (unpubl.). one sample from the hornemantoppen granitoids from the same locality as samples 14-1 and spz-5 gave ages of ca. 780,565 and 500 ma. the last two ages are similar to the older age obtained from spz-5, while the first one is still older. multi-grain analyses of zircon from the same locality as a grey granite sample 15-1 provided ages of 1,136 and 1,050 ma, not far from the age of spz-4, which is from a different sample additional rb-sr and single-grain zircon datings of caledonian granitoid rocks 163 m :i spz-5 (1) 547 ma 6= +/-i9 m;i .. i spz-4 (1) 952 ma d= +/-20 ma i onn ma 6 spz-3 (2) 423 ma u'= +/-22 ma fig. 8. 207pb/z06pb ages of the granitoid rocks. numbers in parentheses are the number of grains evaporated together. vertical axis represent the number of scans. a: spz-5, hornemantoppen granitoid. b: 4 2 ~~ d spz-4, inherited zircon of the grey granite. c: spz-3, a three grain age of the grey granite. d: spz-3, a two-grain age of the grey granite. e: 16-1, a dioritic 250 . dyke rock from amsterdam~ya. but from the same grey granite body. the relatively good agreement between these preli minary multi-grain analyses and the present results suggest that the former data are useful for general considerations at the present situation of knowledge where the amount of age data is very limited. a weakly metamorphosed gabbro diorite from the same locality as sample 16-1, but from a different dyke, gave multi-grain evaporation ages of 502 and 445 ma. these ages are higher than the present result, 421 ? 36 ma, from 16-1. it is natural that the latter is a dyke. six multi-grain analyses were also attempted on the zircons from the schists of the signehamna formation to the east of krossfjorden, resulting in ages ranging from 1,645 to 1,660 ma. six multi grain evaporation analyses were made on zircons from the gneisses of the kongsvegen formation in 400 ma spz-3 (3) 461 ma d= + i 4 2 m a 250 i i n 5 i) c 1l 16-1 (i) 421 ma 2 0 250 h 40 e l c ma the middle of braggerhalvaya to the south of kongsfjorden, and the results gave a wide age range from 1,720 to 960 ma. no younger age than 960 ma has been obtained. these ages from both areas must be detrital zircon ages. these results from the schists and gneisses of the northwestern and western regions of spitsbergen suggest that the provenance materials to the sedimentary protoliths of these metamorphic rocks are paleo to meso-proterozoic in age, and that these rocks were first metamorphosed during the grenvillian period, ca. 1,100 to 950 ma ago. conclusions bulk rock chemistry of the analysed samples shows that both the grey granites and the 164 ju. a. balasov et al. hornemantoppen granitoids are s-type, continen tal, post-orogenic granitoids. new rb-sr whole rock isochron age of the hornemantoppen granitoids, ca. 413 2 5 ma, conforms with the previous result of h’elle (1979). one of the single-grain zircon 207pb/ pb ages of the rocks is conformable with the rb-sr age within the error range, while the other suggests the presence of some inherited compo nent. the youngest single-grain zircon ages of the grey granites are identical, ca. 424 and 423 ma, to that of the hornemantoppen granitoids. while another grain indicates an minimum inherited age as old as ca. 950 ma. the dioritic dyke cutting the migmatites in amsterdamaya has an age similar to the grey granites and is possibly older than the horneman toppen granitoids. the present dating results, together with previous data, show that both types of granitoid rocks were emplaced during the caledonian period, and the hornemantoppen granitoids are younger than the grey granites based on observed cutting relation in the field, though the rb-sr and zircon data are identical. although there is a single-grain zircon result from the grey granites, which suggests a grenvillian age, pre-caledonian basement has not been proven by the present data. the zircon grain showing a 952 5 20 ma age may be derived from deep-seated basement or from detrital grains in the protolith, and in both cases grenvillian rocks must have existed within or near the area where these grey granites were formed. peucat et al. (1989) reported a grenvillian metamorphic age from biskayerhalvaya, about 20 km east of the present area. preliminary multi grain zircon data also suggest grenvillian and older basement in the northwestern spitsbergen. d 6 acknowledgements. this study has been realised by the logistic help of norwegian polar institute, oslo, n o w a y , and the polar marine geologic expedition, lomonosov, st. peterburg, russia. partial financial support for the laboratory work at the university of rennes, france, was provided by the french-norwegian cultural cooperation project. the authors thank to a. macann for language improvement and two referees for critical comments to the manuscript. references abakumov, s. a. 1976a: geologieeskij oeerk okrestonostej kross-f‘orda, 0. spicbergen. in geologija sval’barda. (geological sketch of the environs of krossfjorden. in geology of svalbard). niiga, 5-2. leningrad. abakumov, s. a. 1976b: osnovnye b r t y geologii i metamor fizma severo-zapada s + picbergen. in geologija sval’barda (foundamental characteristics of geology and metamorphism in northwestern spitsbergen. in geology of svalbard). nliga, 22-32. leningrad. abakumov, s. a. 1979: peculiar features of regional meta morphism of northwestern spitsbergen. norsk polarinst. skr. 167, 29-36. blomstrand, c . w. 1864: geognostiska iakttagelser under en resa till spitsbergen dr 1861. k. svemk vetensk. akad. handl. 4(6). stockholm. bucher-nurminen, k. 1981: petrology of chlorite-spinel marbles from nw spitsbergen (svalbard). lithos 14, 203-213. cappel, b. w. & white, a. i. r. 1974: two contrasting granite types. pacific geol. 8, 173-174. debon, f. & le fort, p. 1983: a chemical-mineralogical classification of common plutonic rocks and associations. trans. roy. sac. edinburgh: earth sci. 73, 135-149. ewart, a. 1976: mineralogy and chemistry of modern orogenic l a v a s s o m e statistics and implications. earth planer. sci. lett. 31, 4 1 7 4 3 2 . gaimard, p. 1855: voyages en scandinavie, en lapponie, au spitzberg et aux feroe, pendant les anne‘es 1838, 1839, et 1840 sur la corvette la recherche. observations geologiques sur la scandinavie et le spitzberg, par m.j. durocher. livraison 29c, 4 6 9 4 7 8 . gayer, r. a,, gee, d. g., harland, w. b., miller, j. a,, spall, h. r., wallis, r. h. & winsnes, t. s. 1966: radiometric age determinations on rocks from spitsbergen. norsk polarinst. skr. 137. 39 pp. gee, d. g. & hjelle, a. 1966: on the crystalline rocks of northwest spitsbergen. norsk polarinst. arbok 1 9 6 4 . 3 1 4 5 . hjelle, a. 1974: the geology of danskoya and amsterdamoya, north-west spitsbergen. norsk polarinst. skr. 158, 7-37. hjelle, a. 1979: aspects of the geology of northwest spitsbergen. norsk polarinst. skr. 167, 37-62. hjelle, a. & lauritzen, 8. 1982: geological map svalbard 1:500,000, sheet 3g spitshergen northern part. norsk polarinst. skr.154-c. 15pp. hoel, a. 1914: exploration du nord-ouest du spitsberg (mission isachsen). res. des campagnes scienl. du prince de monaco. xlii, (111). geologie. monaco. holtedahl, 0. 1926: notes on the geology of northwestern spitsbergen. result. av stats-underst. spitsbergeneksp. 1 (8). 1-28. oslo. irvine, t. n. & baragar, w. r. 1971: a guide to the chemical classification of the common igneous rocks. can. j . earth sci. 8 , 523-548. klaper, e. m. 1986: the metamorphic evolution of gamet cordierite-sillimanite gneisses of nw spitsbergen (sval bard). schweiz. mineral. petrogr. mitt. 6 6 , 295-313. kober, b. 1986: whole-grain evaporation for z07pb/z06pb age investigations on single zircons using a double-filament thermal ion source. c o n k miner. petrol. 93, 428-490. krasil’seikov, a. a. 1973: stratigrafija 1 paleotektonika dokambrija-rannego paleozoja spicbergena (stratigraphy and palaeotectonics of the precambrian-early palaeozoic of spitsbergen). niiga trudy 172. leningrad. 120 pp. ludwig, k. r. 1991: isoplot a plotting and regression program for radiogenic isotope data, version 2-56. u.s.g.s. open file report, 9 1 4 5 . additional rb-sr and single-grain zircon datings of caledonian granitoid rocks 165 maniar, p. d. & piccoli, p. m. 1989 tectonic discrimination of granitoids. geol. sac. am. bull. 101, 635443. ohta, y. 1969: the geology and structure of metamorphic rocks in the smeerenburgfjodden area, northwest vestspitsbergen. norsk polarinst. arbok 1967, 52-72. ohta, y. 1974a: tectonic development and bulk chemistry of rocks from the smeerenburgfjorden area, spitsbergen. norsk polarinst. skr. 158, 69-107. ohta, y. 1974b geology and structure of the magdalenefjor den area, spitsbergen. norsk polarinst. skr. 158, 38-68. orvin, a. 1940: outline of the geological history of spitsbergen. skr. svalbard og ishavet. 78. 57 pp. peucat, j . j., ohta, y., gee, d. g. & bernard-griffiths, j., 1989: u-pb, sr and nd evidence for grenvillian and latest proterozoic tectonothermal activity in the spitsbergen caledonides, arctic ocean. lifhos 22, 275-285. ravich, m. g. 1979: is there an early precambrian granite gneiss complex in northwestern spitsbergen? norsk polar inst. skr. 167, 9-28. schenk, e. 1937: kristallin und devon im nordlichen spitzbergen. geol. rundr. 28, 112-124. schetelig, j. 1 9 1 2 exploration du nord-ouest du spitsberg (mission isachsen). res. des campagnes scient. du prince de monaco. xliii, (iv), les formations primitives. monaco. stacey, j. s. & garners, j. d. 1975: approximation of terrestrial lead isotope evolution by a two-stage model. earth planet. sci. lett. 26, 207-221. streckeisen, a. l. 1 9 7 6 classification and nomenclature of igneous rocks. n. jb. miner. abh. 107, 144-240. odwyer.indd 209o’dwyer et al.: polar research 20(2), 209–216 north atlantic water in the barents sea opening, 1997 to 1999 jane o’dwyer, yoshie kasajima & ole anders nøst north atlantic water (naw) is an important source of heat and salt to the nordic seas and the arctic ocean. to measure the transport and variability of one branch of naw entering the arctic, a transect across the entrance to the barents sea was occupied 13 times between july 1997 and november 1999, and hydrography and currents were measured. there is large variability between the cruises, but the mean currents and the hydrography show that the main inflow takes place in bjørnøyrenna, with a transport of 1.6 sv of naw into the barents sea. combining the flow field with measurements of temperature and salinity, this results in mean heat and salt transports by naw into the barents sea of 3.9×1013 w and 5.7×107 kg s-1, respectively. the naw core increased in temperature and salinity by 0.7 ºc yr-1 and 0.04 yr-1, respectively, over the observation period. variations in the transports of heat and salt are, however, dominated by the flow field, which did not exhibit a significant change. j. o’dwyer, y. kasajima & o. a. nøst, norwegian polar institute, polar environmental centre, n-9296 tromsø, norway. the influence of the flow of warm and saline north atlantic water (naw) into the nordic seas and the arctic ocean has long been recognized (helland-hansen & nansen 1909; hansen & østerhus 2000). the strong interactions between the ocean, ice and atmosphere at high latitudes lead to large transfers of heat from the naw to the atmosphere, making the region warm for its latitude, and the inflow of naw to the arctic through the barents sea is important in the formation of the dense waters that form the deep limb of the thermohaline circulation. anomalies of heat and freshwater, such as the great salinity anomaly (dickson et al. 1988), that are advected through the arctic, including the barents sea, appear to be an important link in the feedback loops controlling arctic climate (mysak 1998). to understand the climate of the region and the role it plays in the larger scale climate system that includes the north atlantic and arctic oceans, it is necessary to understand the exchanges between the barents and norwegian seas, and the variability of these exchanges. this is the motivation for the veins (variability of exchanges in northern seas) project, which had the objective of measuring and modelling the variability of fluxes between the atlantic and arctic oceans to understand the role of the high latitude oceans in the climate system. as part of veins, the norwegian polar institute carried out a series of cruises along the barents sea opening (bso). here we focus on the variability of the branch of naw flowing into the barents sea and attempt to identify some of the mechanisms contributing to the observed variability. the results described here are based on temperature, salinity and velocity measured on a section along the bso that was repeated every three to four months between july 1997 and november 1999. as shown in fig. 1, naw is transported northward along the norwegian coast by the norwegian atlantic current. the current splits at the 210 north atlantic water in the barents sea opening, 1997 to 1999 bso and one branch flows eastward into the barents sea, whilst the remainder continues northward to fram strait and directly into the arctic ocean (hansen & østerhus 2000). flow through the bso occurs in the channels on either side of the island of bjørnøya. the deepest is bjørnøyrenna, in the south, with a maximum depth of nearly 500 m. the water entering bjørnøyrenna can flow across the entire barents sea without encountering topography shallower than 200 m; this is the main inflow path for naw. storfjordrenna to the north is 300 m deep, but it shoals to the east, and is blocked by spitsbergenbanken at about 23° e. naw is not observed in storfjorden to the north either (haarpaintner et al. unpubl. ms), so the naw in storfjordrenna must recirculate within storfjordrenna and return west, with properties that have been modified by cooling and mixing. however, storfjordrenna does provide a path to the west for the cold and saline deep water that is formed in storfjorden (schauer 1995). the barents sea is a key region for water mass modification in the arctic (swift et al. 1983). interactions with ice and atmosphere, and mixing in the barents sea, significantly modify the water masses before they enter the arctic basin, in contrast to the naw that enters relatively unchanged through fram strait. there are large seasonal variations in conditions in the barents sea. in fig. 1. the main features of the topography and circulation in the bso. ctd stations are marked . 211o’dwyer et al.: polar research 20(2), 209–216 winter the northern barents sea is ice-covered. cooling and brine-rejection increases the density of the surface layer and, combined with mechanical mixing by the wind, this leads to vertical homogenization of the water column. the dense water that is formed fills the northern barents sea. some flows northwards into the arctic ocean and some southwards through the bso into the norwegian sea (pfirman et al. 1994). in spring and summer the sea ice melts, creating a fresh surface layer; warming of the surface layer during the summer further increases the stability of the water column. this inhibits vertical mixing, and tends to isolate the deeper water from atmospheric contact, conserving the properties of the water masses created in the winter in the deep water. observations the section along the bso shown in fig. 1 was repeated 13 times between july 1997 and november 1999. the section consisted of temperature and salinity measurements at 38 ctd stations, and continuous measurements of velocity by shipmounted adcp (details are given in table 1). ctd salinities were calibrated using water samples collected at each station. on most stations water samples were collected at the surface and the bottom, except in the shallow water near bjørnøya, where only the bottom sample was collected. during veins01, salinities were analysed on board and for the other cruises salinities were analysed after the cruise (table 1). samples for which the difference between the bottle and ctd values was greater than two standard deviations from the mean were not used for calibration. a linear fit between the remaining sample salinities and ctd salinities was used to correct the ctd salinities. the ctd data were checked for density inversions and points were removed if the vertical gradient of potential density was greater than 0.1 kg m-3 m-1. the adcp measurements cover the top 200 m. they thus miss the flow in the deepest parts of bjørnøyrenna and storfjordrenna. profiles of northward and eastward velocities were averaged over ten minutes and processed using the gf icodas package. the tidal velocities were subtracted from the processed data using results from a barotropic tidal model (gjevik et al. 1994). there are several possible sources of uncertainty in the transports determined from the adcp measurements, including: 1) the adcp measurements are subject to errors due to the ship’s motion. velocities measured along the ship’s track are most strongly affected, and in this case, where the ship’s track lies nearly north—south, errors are minimized by only considering the east—west flow. 2) the instantaneous flow field is dominated by the tides, therefore a relatively small error of around 10 % in the tidal component obtained from the model could lead to an error with a magnitude similar to the mean flow. 3) there are large short timescale (from days to months) variations in the flow. because these timescales are not properly resolved by the adcp measurements, there could be aliassing of this short timescale variability. therefore, although these data are a useful supplement to the hydrographic data, they should be treated with a certain amount of caution. the mean conditions are described below. to study the variability, the naw cores in bjørnøyrenna and storfjordrenna are identified for each cruise from the ctd data as the salinity maximum where t > 2 °c. to determine the transport of naw, ctd and adcp measurements are combined as follows: for each cruise the vertically averaged velocity is interpolated onto 0.1° latitude intervals, and for each interval the ctd data within 0.2° latitude are averaged to give temperature and salinity profiles. points where s > 34.95 and t > 2 °c are identified as being naw. the commonly used definition in the nordic seas is s > 35 (helland-hansen & nansen 1909), but table 1. details of the thirteen veins cruises, giving the number of ctd stations occupied, the ctd used (neil brown, nb, or seabird, sb). crosses in the final two columns indicate whether water samples were taken and whether adcp measurements were made. cruise date no. of ctd type of water adcp stations ctd samples veins01 july 1997 38 nb × × veins02 nov. 1997 37 nb × veins03 feb. 1998 10 nb veins04 mar. 1998 29 nb × × veins05 may 1998 30 nb × × veins06 july 1998 38 nb × × veins07 sept. 1998 35 nb × × veins08 nov. 1998 38 nb × veins09 feb. 1999 22 nb/sb × veins10 may 1999 32 sb × × veins11 july 1999 38 sb × × veins12 sept. 1999 26 sb × veins13 nov. 1999 38 sb × × 212 north atlantic water in the barents sea opening, 1997 to 1999 the fresher definition is often used in the barents sea since the temperature and salinity of naw decrease northwards (loeng 1991). temperature, salinity and velocity at the points identified as naw are used to calculate transports of volume, heat and salt. heat transport is determined relative to 0 °c and salt transport relative to 0. the seasonal and interannual variability of the core values is described in later sections. mean conditions ctd sections from july 1997 and march 1998 (fig. 2) show conditions typical for the bso. in the summer there is a warm, fresh layer of meltwater at the surface (fig. 2a, b) and this leads to strong stratification. in winter increased vertical mixing means that the water column becomes more homogeneous (fig. 2c, d). naw is present throughout the year as a warm salinity maximum, with its main core on the southern slope of bjørnøyrenna at a depth between 150 and 250 m. the naw in storfjordrenna is cooler and fresher than that in bjørnøyrenna, and naw as we have defined it here is not always present in storfjordrenna. this probably reflects the fact that storfjordrenna lies further along the flow path of naw than bjørnøyrenna does, and the naw in storfjorden has undergone more mixing with the surrounding cold, fresh arctic water masses. the cold, dense water mass at the bottoms of the channels in the bso is formed in winter in the northern barents sea (pfirman et al. 1994) and in storfjorden (schauer 1995). the instantaneous velocity field is dominated by barotropic tidal currents. in the shallow water surrounding bjørnøya, there is flow of up to 40 cm s-1, and in the deeper channels the flow reaches about 10 cm s-1. the detided currents remain strongly barotropic, and the following analysis uses the vertically averaged currents. transports vary greatly between cruises, but the fig. 2. conditions in the bso in july 1997: (a) temperature and (b) salinity; and in march 1998: (c) temperature and (d) salinity. note that the section is looking eastward, into the barents sea. (a) (b) (c) (d) 213o’dwyer et al.: polar research 20(2), 209–216 positive correlation between the transports in storfjordrenna and bjørnøyrenna (fig. 3) indicates that they share a common forcing agent. this is probably the wind, as suggested by loeng et al. (1997) and ådlandsvik & hansen (1998). the mean circulation over the top 200 m, determined from all the cruises (fig. 4) appears to be topographically controlled. the circulation in each hollow is cyclonic, with eastward flow to the south and westward flow to the north. this implies either recirculation within the hollow, or two separate water masses flowing in opposite directions on each bank of the hollow. the main inflow, on the southern slope of bjørnøyrenna between about 72° and 73° n, has a velocity of about 10 cm s-1, coinciding with the core of the naw (fig. 2). the flow in bjørnøyrenna resembles that observed using current meters by blindheim (1989). haugan (1999) and furevik (2001) report two cores of naw in bjørnøyrenna, and there is an indication of two inflows on the bjørnøyrenna slope, although they do not seem to be associated with separate cores in the ctd data (fig. 2). on the northern slope of bjørnøyrenna, a current of a similar magnitude flows in the opposite direction, associated with the colder, fresher outflow from the barents sea. there are strong currents near bjørnøya, but this area is shallow and the associated transports are small. on average 1.6 sv of naw flows into the barents sea through bjørnøyrenna, carrying heat and salt amounting to 3.9×1013 w and 5.7×107 kg s-1, respectively. north of bjørnøya, in storfjordrenna, the transports are, respectively, -0.4 sv, -0.7×1013 w and -1.5×107 kg s-1. this appears puzzling, since it implies a flow of naw out of the barents sea through storfjordrenna; however, the magnitude of this transport is similar to the standard error of the mean transport and it is therefore also consistent with there being no net flow of naw through storfjordrenna. seasonal variability the plots of temperature and salinity by month in fig. 5 (a, b) show that naw tends to be cooler and fresher in winter than summer. in bjørnøyrenna the temperature varies between 4.6 °c and 7.3 °c and salinity between 35.07 and 35.24 during the observational period. the seasonal cycle in storfjordrenna is more pronounced: temperature varies between 2.7 °c and 5.6 °c and salinity between 34.97 and 35.13. however, in the 29 months during which the observations were carried out, the variation between summers could be as large as the variation between summer and fig. 3. transport in storfjordrenna plotted against transport in bjørnøyrenna. fig. 4. the mean vertically averaged velocities, shown in relation to the bso topography. 214 north atlantic water in the barents sea opening, 1997 to 1999 fig. 5. (a) temperature and (b) salinity of the naw, and transports of (c) volume, (d) heat and (e) salt by naw, plotted against month to show seasonal variability. in (a) and (b) crosses represent bjørnøyrenna and circles storfjordrenna. in (c) – (e) black bars represent bjørnøyrenna and white bars storfjordrenna. fig. 6. (a) temperature and (b) salinity of the naw core, and transports of (c) volume, (d) heat and (e) salt by naw, plotted against time to show interannual variability. symbols in the plots are as for fig. 4. (a) (b) (c) (d) (e) (a) (b) (c) (d) (e) 215o’dwyer et al.: polar research 20(2), 209–216 winter, as illustrated by the large differences in july temperatures (1 °c) and salinities (0.08) in bjørnøyrenna over the three years of observations (fig. 5a, b). midttun (1990) noted similar large interannual variability for the years 1977 to 1987. figure 5c shows the large variability of the volume transport through the bso. the variation of heat and salt transports through the bso (fig. 5d, e) are mainly determined by the flow field, and the effects of temperature and salinity variations are relatively small. there appear to be generally higher transports in july, and low transports in november, suggesting a possible seasonal cycle, although the single transport measurement in march is also large. interannual variability figure 6 (a, b) shows that the temperature and salinity of the naw cores in both bjørnøyrenna and storfjordrenna increase steadily between 1997 and 1999. in bjørnøyrenna, temperature and salinity increase by 0.7 °c yr-1 and 0.04 yr-1, respectively. in storfjordrenna the increases are 0.7 °c yr-1 and 0.02 yr-1, respectively. the t-s diagram in fig. 7 shows that temperature and salinity from bjørnøyrenna and storfjordrenna lie on a straight mixing line, with a correlation coefficient of 0.93. the various naw cores could therefore be created by mixing between two source water masses with constant properties, for example, the most extreme naw observed, with t = 7.3 °c and s = 35.24, and a cold, fresh water mass with t = 0 °c and s = 34.80. there is no significant trend in naw transport during the short observation period (fig. 6c). any interannual signal is dominated by the large short timescale variability. therefore, despite the increasing trends of temperature and salinity, no significant increases in the transports of heat and salt through the bso are observed (fig. 6d, e). discussion adcp measurements over the top 200 m of the bso show currents that are dominated by barotropic tides. the mean flow calculated over all the cruises is topographically controlled, with cyclonic circulations in both bjørnøyrenna and storfjordrenna (fig. 4). the main flow of naw occurs in bjørnøyrenna, where (from the velocities measured over the top 200 m) an average transport of 1.6 sv of naw into the barents sea imports heat and salt at rates of 3.9×1013 w and 5.7×107 kg s-1, respectively. the mean transport and circulation in bjørnøyrenna agree with those observed by blindheim (1989). the mean transport in storfjordrenna indicates a westward flow of 0.4 sv of naw, out of the barents sea. considering the uncertainties in the adcp measurements, this result is consistent with there being no net transport of naw through storfjordrenna. the transport in bjørnøyrenna appears to be higher in summer and low in winter. this does not agree with earlier geostrophic calculations and modelling results (loeng et al. 1997), which show a winter maximum, and our result may be caused by aliassing of the large short timescale wind-driven variability. whilst mean transport values appear to be robust, the large variability of the flow means that a longer timeseries of observations would be necessary to properly measure variability on seasonal and interannual timescales. current meter moorings may offer the best method of observing this flow, since they give good timeresolution, and a relatively coarse spatial resolution may be sufficient to observe the main features of the flow of naw in bjørnøyrenna. the hydrographic fields are less subject to short timescale variability than the velocity fields, and the patterns of variability of temperature and salinity on seasonal and interannual timescales fig. 7. t-s diagram of the core properties in bjørnøyrenna and storfjordrenna. there is a correlation of 0.93 between t and s. 216 north atlantic water in the barents sea opening, 1997 to 1999 are clearer than those of the transport variability. on a seasonal timescale, naw is colder and fresher in the winter than the summer. on an interannual timescale, during the period of observation there are increases of 0.7 °c yr-1 in the temperature and 0.04 yr-1 in the salinity of the naw entering the barents sea. trends of this magnitude that continue for three or four years are normal for the barents sea, as can be seen in the temperature record from the kola section shown by ådlandsvik & loeng (1991). despite the changes in temperature and salinity, no significant increase is observed in the imports of heat and salt to the barents sea by naw, due to the large variability of the transport discussed above. the t-s diagram in fig. 7 includes naw core properties for both bjørnøyrenna and storfjordrenna, from different times of year, and different years. there is a straight line through the points, which suggests that a common mechanism, involving mixing between two sources with constant properties, is responsible for creating all the different varieties of naw observed between 1997 and 1999. thus cooler and fresher naw is formed by increased mixing in winter, and the naw in storfjorden is cooler and fresher than in bjørnøyrenna, also due to mixing along its path. analagously, the longer-term warming and salinification of naw may be due to a reduction in mixing. furevik (2001) suggests two possible causes of long timescale variability in the naw entering the barents sea: an anomaly may either be advected from the north atlantic, or be created within the nordic seas by changes in the rates of heat loss and mixing along the path of the naw. our observation corresponds to the second mechanism, where reduced mixing rates along the path of the naw in the nordic seas could lead to increasing temperature and salinity of the naw in the bso. in conclusion, the ctd data from the series of cruises in the bso show the seasonal cycles in temperature and salinity, and show evidence of variability on a longer timescale. however, the large short timescale variability of the flow field means that the seasonal cycle and longer-term variability of the transport are not properly resolved by the adcp data. acknowledgements.—this work formed part of the eu funded veins project, and was also partly supported by the norwegian polar institute. we would like to thank the captains and crews of rv lance for their help on the npi veins cruises. suggestions from the two anonymous reviewers were helpful in improving the quality of the final paper. references ådlandsvik, b. & hansen, r. 1998: numerical simulation of the circulation in the svalbardbanken area in the barents sea. cont. shelf res. 18, 341–355. ådlandsvik, b. & loeng, h. 1991: a study of the climatic system in the barents sea. polar res. 10, 45–49. blindheim, j. 1989: cascading of barents sea bottom water into the norwegian sea. rapp. p.-v. reun. cons. int. explor. mer 188, 49–58. dickson, r. r., meincke, j., malmberg, s. a. & lee, a. j. 1988: the “great salinity anomaly” in the northern north atlantic 1968–1982. prog. oceanogr. 20, 103–151. furevik, t. 2001: annual and interannual variability of atlantic water temperatures in the norwegian and barents seas: 1980–1996. deep-sea res. 48, 383–404. gjevik, b., nøst, e. & straume, t. 1994: model simulations of the tides in the barents sea. j. geophys. res. 99(c2), 3337–3350. haarpaintner, j., o’dwyer, j., gascard, j.-c., haugan, p. m., schauer, u. & østerhus, s. unpubl. ms: seasonal water masses, circulation and brine formation observed in storfjorden. hansen, b. & østerhus, s. 2000: north atlantic—nordic seas exchanges. prog. oceanogr. 45, 109–208. haugan, p. m. 1999: structure and heat content of the west spitsbergen current. polar res. 18, 183–188. helland-hansen, b. & nansen, f. 1909: the norwegian sea, its physical oceanography. based on the norwegian researches 1900–1904. report on norwegian fishery and marine investigations 2(2). bergen. loeng, h. 1991: features of the physical oceanographic conditions of the barents sea. polar res. 10, 5–18. loeng, h., ozhigin, v. & ådlandsvik, b. 1997: water fluxes through the barents sea. ices j. mar. sci. 54, 310–317. midttun, l. 1990: surface temperatures of the barents sea. polar res. 8, 11–16. mysak, l. a. & venegas, s. a. 1998: decadal climate oscillations in the arctic: a new feedback loop for atmosphere– ice–ocean interactions. geophys. res. lett. 25, 3607–3610. pfirman, s. l., bauch, d. & gammelsrød, t. 1994: the northern barents sea: water mass distribution and identification. in o. m. johannessen et al. (eds.): the polar oceans and their role in shaping the global environment. geophys. monogr. ser. 85. pp. 77–94, washington, d. c.: american geophysical union. schauer, u. 1995: the release of brine-enriched shelf water from storfjord into the norwegian sea. j. geophys. res. 100(c8), 16,015–16,028. swift, j. h., takahashi, t. & livingston, h. d. 1983: the contribution of the greenland and barents seas to the deep water of the arctic ocean. j. geophys. res. 88(c10), 5981–5986. doi:10.3402/polar.v35.29383 r e s e a r c h / r e v i e w a r t i c l e adjustment of pigment composition in desmarestia (desmarestiaceae) species along a sub-antarctic to antarctic latitudinal gradient andrés mansilla,1,2 fabio méndez,1,2,3 silvia murcia,1 juan pablo rodrı́guez,1,2,3 johanna marambio,1,2,3 sebastián rosenfeld,1,2,3 nair yokoya4 & kai bischof5 1 laboratory of antarctic and sub-antarctic marine ecosystems, university of magallanes, 01855 bulnes ave., punta arenas 6200000, chile 2 institute of ecology and biodiversity, las palmeras st. 3425, ñuñoa, santiago 8320000, chile 3 conservation and management of natural resources in sub-antarctic environments ms program, university of magallanes, 01855 bulnes ave., punta arenas 6200000, chile 4 institute of botany, são paulo state department of the environment, 3687 miguel estéfano ave., são paulo 04301-012, sp, brazil 5 marine botany department, university of bremen, nw2 leobener st., bremen de-28359, germany keywords macroalgae; phaeophyceae; photosynthesis; physiology; environmental heterogeneity; chile. correspondence silvia murcia, laboratory of antarctic and sub-antarctic marine ecosystems, university of magallanes, 01855 bulnes ave., punta arenas 6200000, chile. e-mail: silvia.murcia@umag.cl abstract photosynthesis at high latitudes demands efficient strategies of light utilization to maintain algal fitness and performance. the fitness, and physiological adaptation, of a plant or algae species depends in part on the abundance and efficiency of the pigments it can produce to utilize the light resource from its environment. we quantified pigment composition and concentration in six species of the brown macroalgal genus desmarestia, collected from subantarctic sites (strait of magellan, beagle channel�cape horn province) and sites on the antarctic peninsula and adjacent islands. sub-antarctic desmarestia species exhibited lower concentrations of chlorophyll a, chlorophyll c and fucoxanthin than endemic antarctic species. antarctic samples of d. menziesii and d. antarctica collected along a decreasing latitudinal gradient showed spatial and interspecific differences in light-harvesting pigment composition. our results suggest distinct physiological adjustments in desmarestia species in response to heterogeneous abiotic environmental conditions. the marine subantarctic and antarctic ecosystems are characterized by harsh environments (e.g., extreme irradiance, photoperiod, temperature, salinity) to which the physiology of macroalgal species must adapt. the chilean sub-antarctic ecoregion of magallanes (or magellan) hosts a coastal, benthic community that is highly distinct from other temperate rocky shores on the south american continent in terms of species composition, richness and structure. such distinctions could be the result of several factors, such as the geomorphology generated by the glacial erosion during the advance and retreat of ice in the quaternary (silva & calvete 2002); oceanographic gradients combining unique current flows, salinity, and thermal (dayton 1985; silva & calvete 2002), photoperiod and irradiance regimes; presence of glaciers with predominant west-to-east gradients of winds and rainfall (aravena & luckman 2009) and freshwater coastal discharge; variable substrate types with abrupt change in geomorphology of the sub-antarctic system of fjords and channels (valdenegro & silva 2003), resulting in unique physical and biogeochemical seawater conditions (e.g., nutrient cycles, carbonate system dynamics [torres et al. 2014]) that generate a distinct algal structure. the environmental heterogeneity governing sub-antarctic and antarctic coastal ecosystems has shaped the evolutionary history and physiological adaptations of the local macroalgal flora. from phylogenetic, morphological and eco-physiological studies of the genus desmarestia (lamouroux 1813) conducted in the antarctic ecoregion of magallanes, it was polar research 2016. # 2016 a. mansilla et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 29383, http://dx.doi.org/10.3402/polar.v35.29383 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/29383 http://dx.doi.org/10.3402/polar.v35.29383 found this species originated from an antarctic ancestor, then radiated north, eventually reaching the northern hemisphere through long-distance natural dispersal (peters et al. 1997). within the sub-antarctic chilean ecoregion of magallanes, the genus desmarestia is represented by d. confervoides (bory de saint-vincent) m.e. ramı́rez & a.f. peters, d. chordalis j.d. hooker & harvey and d. ligulata (stackhouse) j.v. lamouroux. currently, d. distans and d. muelleri are considered subspecies of d. ligulata (setchell & gardner 1925; guiry & guiry 2014; yang et al. 2014). the representative desmarestia species in the antarctic continent are d. anceps montagne, d. menziesii j. agardh (lamb & zimmermann 1977; wiencke et al. 1995) and d. antarctica silva & moe (moe & silva 1989; wiencke et al. 1991). these desmarestia species, together with himantothallus grandifolius (a. gepp & e.s. gepp) a.d. zinova (1959), comprise a large proportion of the macroalgal biomass along the antarctic peninsula (amsler et al. 1995; brouwer 1996; quartino et al. 2001; quartino et al. 2005), yet are largely understudied despite supporting a diverse, associated floral and faunal community. photosynthetic pigment composition can reveal potential adaptation and acclimation success, and the physiological traits of macroalgae (motten 1995; plastino & mansilla 2004). a species’ reaction to the given radiation climate is determined by the interaction between genetic adaptation and physiological acclimation where adaptation must precede acclimation to changing environmental conditions (bischof et al. 2006). that is, the speciesdependent and variable genetic preadaptations to limiting, but also potentially harmful, radiation would shape its physiology in the natural environment. for example, in lessonia nigrescens of the southern hemisphere, the photosynthetic responses to seasonally changing irradiance levels are some of its adaptations, along with its ontogenic development (huovinen et al. 2006). pigment composition is frequently used as a biomarker to infer physiological adaptations of plants and algae (e.g., dring 1981; ramus 1983) to differing environmental variables across bioregions (falkowski & laroche 1991). laminaria saccharina, for instance, may be capable of optimizing photosynthesis over a wide range of light levels by complex metabolic regulation (machale et al. 1996). and, under variable irradiance, the red algae gracilaria lemaneiformis showed differential vegetative and physiological strategies to adapt to environmental stress by regulating different metabolic processes (e.g., photosystem ii reaction centres normalization; wu et al. 2015). the biochemical reactions of photosynthesis are directly coupled to light availability (plastino & mansilla 2004), and the respective share of chl a as reaction centre pigment to chl c and other accessory pigments, such as the xanthophyll fucox, may reveal adaptive responses towards heterogeneous light and climate, fluctuating with latitude, depth, season or a combination of all (mansilla & alveal 2004; plastino & mansilla 2004). in addition to irradiance and photoperiod (hours daylight: hours darkness), temperature, salinity and nutrients may be further limiting factors at high latitudes, affecting the efficiency of light capture for photosynthesis. our objectives were to examine (1) the adjustments or intraspecific differences in pigment composition and ratio (chl c/chl a; chl c/fucox) in species of the genus desmarestia spatially from sub-antarctic to antarctic marine habitats and (2) the intraspecific differences in pigment concentration in two antarctic species within the genus desmarestia (d. antartica, d. menziesii). we hypothesized that primary (chl a) and accessory (chl c and fucox) pigment composition in desmarestia species will differ among sites along the latitudinal gradient of sub-antarctic to antarctic waters; and along the antarctic peninsula, despite site proximity and past connectivity, reflecting response to local conditions such as different duration and intensity of solar irradiance between regions. the overall results of this investigation will contribute to current knowledge and understanding of macroalgal eco-physiology. marine photosynthetic physiology in sub-antarctic and antarctic irradiance regimes is likely to become increasingly relevant in the context of present and future global changes. materials and methods study sites two sites in chile’s sub-antarctic region and eight sites along the antarctic peninsula were selected to represent a range of environmental conditions (table 1). we used a solar light† radiometer (model: pma 2200) and a yellow spring instrument† handheld multiparameter (model: mps) at some sites (e.g., saint ana) or a conductivity� temperature�depth recorder (sbe 19plus v2 seacat sea-bird electronics inc.) measurements to first 10 m depth at other sites (e.g., deception). when not available, approximates of environmental data were obtained from published literature for the given site (e.g., santana et al. 2006; clarke et al. 2008; smith & comiso 2008; ceazamet 2010; table 1). abbreviations in this article chl a, b, c: chlorophyll a, b, c fucox: fucoxanthin fw: fresh weight par: photosynthetically active radiation pigment composition in desmarestia species a. mansilla et al. 2 (page number not for citation purpose) citation: polar research 2016, 35, 29383, http://dx.doi.org/10.3402/polar.v35.29383 http://www.polarresearch.net/index.php/polar/article/view/29383 http://dx.doi.org/10.3402/polar.v35.29383 field sample collection fronds of desmarestia confervoides and the subspecies d. ligulata subsp. ligulata f. distans and d. ligulata subsp. muelleri were collected in the austral summer period (december 2011�february 2012) at two sites along the strait of magellan to the beagle channel (table 1; fig. 1). d. antarctica, d. menziesii and d. anceps were collected in antarctica by scuba diving in february 2013 off fildes bay (fildes), hanna point (hanna), prat point (prat), deception island (deception), spring point (spring), argentine islands (argentine), rothera base (rothera; except d. antarctica, not found) and carvajal base (carvajal; table 1, fig. 1). all specimens were placed in freeze�cooler containers to prevent sulfation of desmarestia individuals and/or degradation of pigments from exposure to light and temperature changes. sub-antarctic samples were processed upon collection immediately at the laboratory of antarctic and sub-antarctic marine ecosystems, university of magallanes, in punta arenas, chile. antarctic samples were transported in coolers, over the short 5to 10-min zodiac ride back to our research vessel where they were frozen at �258c to avoid loss of pigment or similar deterioration for later analysis at the laboratory. pigment analyses seven random, individual samples of each species of desmarestia (7 n �6 species �42) were taken to the laboratory. the frozen samples were thawed, washed with sterilized seawater of salinity 34 psu and were carefully brushed to remove epiphytic organic material. random ca. 2 cm 2 subsamples (0.125 g fw) from the fronds were gently patted with paper towel to remove excess water and weighed in a radwag analytical balance (as 220/c/2) for pigment analysis (seely et al. 1972). our prior work (unpublished) and that of seely et al. (1972) showed that dimethyl sulfoxide readily extracts pigments without further addition of acetone. one ml of dimethyl sulfoxide was added to 0.125 g fw (fw and incubated for 15 min in complete darkness). the supernatant was then placed into a 2.5-ml cuvette for spectrophotometric analysis (genesys 10 uv). no further dilution was necessary. light absorbance was recorded at wavelengths of 480, 582, 631 and 665 nm once completeness of extraction was determined (white samples). pigment concentration was quantified using equations from seely et al. (1972): chl a ¼ a665=72:8; (1) table 1 environmental and habitat variables registered in 2011, 2012 and 2013 during collection of five desmarestia species at 10 study sites in sub-antarctica and antarctica. shown are the mean or mean range values. desmarestia species name study site depth (m) par (me /m2s) salinity (psu) temperature (8c) dissolved o2 (mg/l) habitat substrate type sub-antarctica d. confervoides st ana point 5�7 526.4 32.53 9.73 12.8 cliff d. ligulata subsp. ligulata f. distans st ana point (s53808?; w71800?) 5�7 526.4 32.53 9.73 12.8 cliff d. ligulata subsp. muelleri st ana point 5�7 526.4 32.53 9.73 12.8 cliff d. confervoides paula bay 5�7 164�165 32.17 4.7�10.9 � boulders d. ligulata subsp. ligulata f. distans paula bay (s54855?; w67855?) 5�7 164�166 32.17 4.7�10.9 � boulders d. ligulata subsp. muelleri paula bay 5�7 164�167 32.17 4.7�10.9 � boulders antarctica d. antarctica fildes (s62812?; w58854?) 5�7 729�787 34 2 10.9 cliff d. menziesii fildes 5�7 729�787 34 2 10.9 cliff d. anceps prat (s62827?; w59844?) 9�12 748�768 33.85 2.1 8.0 boulders d. menziesii prat 5�7 748�768 33.85 2.1 8.0 cliff d. antarctica prat 5�7 748�768 33.85 2.1 8.0 boulders d. anceps hanna (s62839?; w60837?) 10 729�787 34 1.8 7.1 cliff d. antarctica hanna 5�7 729�787 34 1.8 7.1 cliff d. menziesii deception (s62859?; w60835?) 5�7 901.21 33.87 2.1 8.0 boulders d. antarctica deception 5�7 901.21 33.87 2.1 8.0 rocky shore d. antarctica spring (s64817?; w61805?) 5�7 729�787 33.4 0�1 � cliff d. menziesii spring 5�7 729�787 33.4 0�1 � cliff d. menziesii argentine (s65814?; w64815?) 5�7 729�787 33.4 0�1 � cliff d. menziesii rothera (s67833?; w68807?) 5�7 1005.9 33.29 1.72 12.6 cliff d. menziesii carvajal (s62812?; w58854?) 5�7 739.6 32.59 0.24 13.3 cliff d. antarctica carvajal 5�7 739.6 32.59 0.24 13.3 rocky shore a. mansilla et al. pigment composition in desmarestia species citation: polar research 2016, 35, 29383, http://dx.doi.org/10.3402/polar.v35.29383 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/29383 http://dx.doi.org/10.3402/polar.v35.29383 chl c ¼ða632 þa582 � 0:297a665þ=61:8; (2) fucox ¼ða480 � 0:772 ða631 þa582 � 0:297a665þ � 0:049a665þ=130 (3) data analysis pigment concentrations were compared among six species (n �7 per species) between sub-antarctic and antarctic sites using the kruskal�wallis non-parametric test because data were not normally distributed. all conclusions were based on a 95% confidence level (p �0.05). in addition, we calculated pigment ratios for species of the subantarctic region and the antarctic peninsula and adjacent islands. all statistical analyses were carried out using the software package statistica, version 7.1 (2004). results study sites the sub-antarctic sites showed lower average salinity and par light (32.35 psu and 345.5 me/m2s, respectively) but generally showed higher average temperature and dissolved oxygen (8.48c and 12.8 mg/l, respectively) than the sites along the antarctic peninsula (33.4 psu, 811.2 me/m2s, 1.7 8c and 9.6 mg/l; table 1). average depth and habitat substrate types where desmarestia specimen could be collected from for this study remained fairly constant variables across sites in both regions (table 1). spatial and interspecific differences overall, higher average concentrations of chl a, chl c and fucox were observed in desmarestia species from antarctic sites compared with sub-antarctic sites (except d. ligulata subsp. muelleri; fig. 2a). among the sub-antarctic species of desmarestia, the highest chl a concentration was measured in d. confervoides from paula bay (beagle channel, cape horn province) and the highest fucox concentration in d. ligulata subsp. muelleri (lowest chl a) from the strait of magellan (fig. 2a). chl a concentration differed significantly between d. ligulata subsp. ligulata f. distans and antarctic d. menziesii (p �0.001; fig. 2a). the chl c content of sub-antarctic d. confervoides was significantly different from all desmarestia species tested (all p b0.002; fig. 2a). statistically, fucox was most variable between the sub-antarctic species (p �0.009; fig. 2a). the ratio of chl c/chl a was similar in the sub-antarctic species d. confervoides (1.68), d. ligulata subsp. ligulata f. distans (2.09) and d. ligulata subsp. muelleri (1.61; fig. 2b). large differences in the ratio of fucox/chl a were found between d. ligulata subsp. muelleri, which exhibited an increased proportion of fucox (5.41 in specimen from paula bay, beagle channel, cape horn; fig. 2b), and all desmarestia species tested. the data show similar pigment concentrations and ratios among the antarctic desmarestiales and overall fairly lower than in sub-antarctic species (all between 0.31 and 0.38; fig. 2b). interspecific differences along the antarctic peninsula: d. antarctica and d. menziesii. the higher concentrations of chl a (0.4590.17 mg.g �1 fw) and chl c (0.2090.08 mg.g �1 fw) were generally found in d. menziesii. but we measured nearly identical concentrations of fucox in both, d. menziesii and d. antarctica (fig. 3a, b). no clear latitudinal effect was observed for chl a concentration in d. menziesii along the antarctic peninsula (fildes to carvajal; table 1, fig. 3a). high concentration of chl a in d. menziesii was recorded in deception, followed by rothera and carvajal (0.6390.04, 0.649 0.03 and 0.6390.05 mg �g�1 fw, respectively), especially at the lowest temperature and salinity sites, near the antarctic circle (table 1, fig. 3a). a decreasing trend in fig. 1 study sites sampled for desmarestia species from which photosynthetic pigments chl a chl c and fucox were extracted. shown are the sites in the sub-antarctic ecoregion: (1) saint ana point (brunswick peninsula); (2) paula bay (beagle channel) and the study sites sampled in the antarctic peninsula; (3) fildes bay (fildes); (4) hanna point (hanna); (5) prat point (prat); (6) deception island (deception); (7) spring point (spring); (8) argentine island (argentine); (9) rothera base (rothera); and (10) carvajal base (carvajal). pigment composition in desmarestia species a. mansilla et al. 4 (page number not for citation purpose) citation: polar research 2016, 35, 29383, http://dx.doi.org/10.3402/polar.v35.29383 http://www.polarresearch.net/index.php/polar/article/view/29383 http://dx.doi.org/10.3402/polar.v35.29383 pigment concentration with increasing latitude was observed from deception to spring and argentine sites. chl a, chl c and fucox in d. menziesii at fildes, spring and argentine, with similar abiotic features (table 1), ranged in similar, and lower, concentrations (all between 0.18 and 0.3090.03 mg �g�1 fw; fig. 3a) than sites with variable par, temperature, salinity or substrate type (table 1). in d. antarctica, chl a concentration varied markedly among sites on the antarctic peninsula, the highest chl a concentrations were recorded in deception (0.5690.2 mg �g�1 fw) and carvajal (0.5690.07 mg �g�1 fw; fig. 3c, d). chl c concentration in d. antarctica decreased towards lower latitudes, from the highest values found at deception (0.1590.09 mg �g�1 fw) to almost half of the concentration in samples from fildes bay. fucox concentrations barely changed along the latitudinal gradient, between deception and spring (fig. 3b) in spite of different environmental features (table 1). we identified overall higher ratios of chl c/chl a in d. menziesii than in d. antarctica, and overall higher ratios of fucox/chl a in d. antarctica than in d. menziesii considering all locations along the antarctic peninsula (fig. 3c, d). among samples of d. menziesii, the highest chl c/chl a ratio was registered in fildes (0.83), the lower latitude site, and the highest fucox/chl a ratio was registered in argentine (fig. 3c). samples of d. antarctica from locations along the antarctic latitudinal gradient, showed low chl c/chl a ratio (fig. 3d). the fucox/chl a ratios in d. antarctica from fildes (1.23) and spring (1.14) were nearly triple (and double in spring point) that of d. menziesii (all sites; fig. 3c, d). discussion we analysed intraspecific and interspecific differences in pigment composition in sub-antarctic and antarctic samples of the genus desmarestia. in the six species studied, fig. 2 (a) mean 9 sd pigment concentration (n �7 per species) of chl a, chl c and fucox and (b) ratios of mean pigment concentration (n �7) of chl c/chl a and of fucox/chl a in species of the genus desmarestia from the sub-antarctic region of chile and the chilean antarctic peninsula. a. mansilla et al. pigment composition in desmarestia species citation: polar research 2016, 35, 29383, http://dx.doi.org/10.3402/polar.v35.29383 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/29383 http://dx.doi.org/10.3402/polar.v35.29383 we found the lowest concentrations of chl a, chl c and fucox in the species from sub-antarctic sites, versus the higher pigment concentrations in species along the antarctic peninsula (table 1; fig. 3), that is, increasing pigment composition towards the prevailing radiation climate. though we registered differences between sites, we expected to see a gradient of photosynthetic pigment concentration reflecting the latitudinal gradient along the antarctic peninsula. we did not see this pigment gradient from our results (fig. 3). such a gradient may have suggested the presence of more accessory pigments in subtidal specimen as a possible strategy to optimize photosynthetic efficiency in regions with shorter light exposure (gómez et al. 1997). nevertheless, we saw an important tendency for higher chlorophyll concentrations at our two sites closest to the polar circle (carvajal and rothera) and the high-latitude site deception, especially with d. menziesii (d. antarctica not collected in rothera). several biotic and abiotic factors, such as temperature, salinity, nutrients (ramus 1978; dhargalkar 2004; nygård & dring 2008) and thalli morphology (peckol & ramus 1988; johansson & snoeijs 2002), may also influence efficiency of light absorption and geographical distribution of macroalgae, survival, growth rates and reproductive success (van den hoek 1982; breeman 1988) at both subantarctic and antarctic sites. at lower temperature (usually higher latitude), high rates of photosynthesis are observed among terrestrial and aquatic plants and usually relate to an increased ratio of chl a to b (e.g., eggert et al. 2006). similar photosynthetic adaptations are most likely in macroalgae at high latitudes, such as those endemic species of the antarctic peninsula. although the depth of light dispersion influences photosynthetic pigment composition, our samples of desmarestia species were all collected in the ca. 5 m depth range in subantarctica and antarctica. it is unlikely that depth was an influential factor on the observed pigment differences. but, the variation in pigment composition among sites on the antarctic peninsula may be influenced by the seasonal variation in light, related in turn to variation in temperature, inducing variable pigment production and metabolic rate (e.g., barko & smart 1981; aguilera et al. 2002). similarly, seasonal sea-ice and snow coverage (zacher et al. 2009), influencing salinity and nutrients, may also affect the physiology of photosynthesis and algal pigment content (e.g., nygård & dring 2008). desmarestia’s pigment concentration may vary under different salinities or according to life history stage (gómez & wiencke 1996). salinity changes affect cellular structures responsible for the synthesis and metabolism of proteins, affecting the life cycle and pigment concentration of some brown algae (nygård & dring 2008) and are likely to affect antarctic species of desmarestia. nutrients also influence photosynthesis and growth rate. for example, cultivation of fucus vesiculosus from the baltic sea (5 psu) showed higher photosynthetic activity (as electron transfer rate) and relative growth rate at low salinities (b10 psu) than f. vesiculosus from the irish sea (35 psu), which decreased sharply in salinities below 20 psu fig. 3 pigment concentration of (a) desmarestia menziesii and (b) d. antarctica along a latitudinal gradient in the antarctic peninsula. shown are the means 9 sd (n �7) concentration of chl a, chl c and fucox, and mean concentration ratios of chl c/chl a and fucox/chl a in (c) d. menziesii and in (d) d. antarctica from study sites along the antarctic peninsula’s latitudinal gradient (n �7). pigment composition in desmarestia species a. mansilla et al. 6 (page number not for citation purpose) citation: polar research 2016, 35, 29383, http://dx.doi.org/10.3402/polar.v35.29383 http://www.polarresearch.net/index.php/polar/article/view/29383 http://dx.doi.org/10.3402/polar.v35.29383 (nygård & dring 2008). fucus specimens from both baltic (5 psu) and irish (20 psu) sites under high-nutrient conditions performed better at low salinities than those grown in low-nutrient cultures (nygård & dring 2008). salinity may therefore be a stronger influence on differences in photosynthesis (and growth) between specimens from two geographic regions or populations, followed by differences in nutrient concentrations. a marked coastal isocline is more characteristic of antarctic than of subantarctic waters (palma et al. 2008) and this might explain the overall lower pigment concentration and ratios in desmarestia from sub-antarctic sites than in those from antarctica. an increase in global temperatures, with its consequent increase in glacial inflows, reduced salinity and increased water turbidity, may alter depth distribution patterns*and therefore productivity*of macroalgal communities, especially in high-latitude regions. though salinity barely differed between sites in both study regions, macroalgal pigment composition and concentration may also vary according to life history stage and thallus morphology (gómez et al. 1997; wiencke, clayton et al. 2006). early stages of d. menziesii would be better adapted to low light intensities than adult stages because they have more pigment composition per unit of biomass and therefore more investment in light-harvesting mechanisms (gómez 2001). alternatively, the desmarestia species we examined have filamentous and laminar thalli, which directly affect the efficiency of light absorption (ramus 1978; peckol & ramus 1988; johansson & snoeijs 2002). thinner species have increased photosynthetic tissue per unit biomass. in d. menziesii, the content of chl a, c and fucox in cultured samples increased with thallus biomass (gómez & wiencke 1997). the pigment composition of d. confervoides, of cylindrical and branched thalli morphology, showed a photosynthetic capacity between that of fleshy and laminar thalli with few cell layers (rautenberger et al. 2009). this morphology is typical of sub-antarctic species. therefore, the greatest concentration of fucox in d. ligulata subsp. muelleri (and d. antarctica, similar morphology) may be due to the laminar thallus morphology potentially influencing pigment concentrations (eggert et al. 2006; navarro et al. 2009) in these sub-antarctic algae. in the sub-antarctic species, no clear pattern in pigment composition was observed from saint ana point to paula bay near cape horn (drake passage; fig. 1). the subantarctic marine habitats are exposed to the unique confluence of three ocean influences (reid 1989) where heavy precipitation, for instance, may set a subtle but important difference among study regions (table 1), in addition to fluvial run off often rare in sites of the antarctic peninsula. this may explain the lower water salinity and higher temperatures registered in general in the physicochemically heterogeneous sub-antarctic environment. the greater variation in, and generally lower, pigment concentration among the sub-antarctic desmarestiales studied may result from low ice or cloud cover, decreased water turbidity from glacial run off, longer daylength in winter or large heterogeneity in the physico-chemical environment (e.g., the advance and retreat of ice [silva & calvete 2002]). we found differences in pigment concentration, especially in chl a, between our study sites along the antarctic peninsula (fildes, prat, deception, spring, argentine, rothera and carvajal), although the concentrations of fucox barely changed among sites. this might be explained by the fact that accessory pigments (carotenoids) are generally less sensitive to severe environments compared with chl a (häder & häder 1989). antarctic macroalgae may be better acclimated than other algae to withstand environmental extremes (irradiance, photoperiod, temperature, salinity, nutrients) that affect the photosynthetic efficiency and pigment composition in high latitudes (gómez et al. 1997; gómez 2001; wiencke, roleda et al. 2006). though we did not measure directly all possible abiotic conditions (cloud cover, transient ice), in other studies, reduced availability of par due to increased water turbidity from glacial influence and depth in coastal antarctica led to decreased macroalgal vertical distribution, photosynthetic parameters (rautenberger et al. 2013) and metabolic carbon balance (deregibus et al. 2015). similar works reveal that the duration of daily exposure, rather than the intensity of light, is most significant for macroalgal productivity and photosynthetic efficiency in coastal areas (gómez et al. 1997; zacher et al. 2009). that is, the increased pigment concentration in antarctic algae during the summer may be a strategy to increase light-harvesting efficiency in an environment with significantly less annual solar radiation than that in temperate to tropical regions (ramus 1981; kirst & wiencke 1995; wiencke, roleda et al. 2006). in contrast, lower pigment content could protect individuals in regions (e.g., sub-antarctic) with lessintense light regime (though available over longer time, that is, months per year, daylength in winter) than the short-and-intense antarctic light regime in the summer (e.g., gómez et al. 1997; gómez 2001). similar patterns have been found in a number of seaweeds from a high arctic site (aguilera et al. 2002). samples were only collected in summer and therefore we were unable to test this potential strategy. in addition, photoperiod is suggested to influence the concentration of accessory pigments in antarctic waters to a greater degree than it a. mansilla et al. pigment composition in desmarestia species citation: polar research 2016, 35, 29383, http://dx.doi.org/10.3402/polar.v35.29383 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/29383 http://dx.doi.org/10.3402/polar.v35.29383 influences chl a (yokoya et al. 2007). but, under field conditions, the effects of photoperiod and irradiance are difficult to disentangle, and thus further studies under controlled laboratory conditions are recommended. it is likely that changes occur in pigment composition of the photosynthetic antenna in sub-antarctic desmarestia (e.g., decrease in chl a with increased light availability in summer; our unpubl. data), but its physiological response must be further studied. in conclusion, despite the environmental extremes of polar waters, macroalgae show physiological adaptations (wiencke 1990). these adaptations can be seen in the photosynthetic apparatus and pigment composition (kirst & wiencke 1995). amid the cumulative global and environmental changes, including increases in average temperatures*and consequent changes in salinity, light intensity and availability*there is a growing need for basic research to guide applied studies (e.g., biotechnology) using algae and their mechanisms of adaptation, survival and irradiance protection as model machinery. acknowledgements this research was funded by chile’s national council for research in science and technology (conicyt) program fondecyt, project 1140940, the millennium scientific initiative (grant p05-002 icm, chile) and the basal financing program of the (grant pfb-23, chile). we thank the resources and support offered by the chilean navy ships ap-46 ƒalmirante óscar viel, and ap�41 aquiles during field expeditions. we are thankful for the graduate scholarships by the institute of ecology and biodiversity granted to fm (icm, p05-002) and jpr (icm, p05-002) and to jm (pfb-23-2008) and sr (icm p05-002). references aguilera j., bischof k., karsten u., hanelt d. & wiencke c. 2002. seasonal variation in ecophysiological patterns in macroalgae from an arctic fjord. ii. pigment accumulation and biochemical defence systems against high light stress. marine biology 140, 1087�1095. amsler c., rowley r., laur d., quetin l. & ross r. 1995. vertical distribution of antarctic peninsular macroalgae: cover, biomass and species composition. phycologia 34, 424�430. aravena j. & luckman b. 2009. spatio-temporal rainfall patterns in southern south america. international journal of climatology 29, 2106�2120. barko j.w. & smart r.m. 1981. comparative influences of light and temperature on the growth and metabolism of selected submersed freshwater macrophytes. ecological monographs 51, 219�236. bischof k., rautenberger r., brey l. & pérez-lloréns j.l. 2006. physiological acclimation to gradients of solar irradiance within mats of the filamentous green macroalga chaetomorpha linum from southern spain. marine ecology progress series 306, 165�175. breeman a. 1988. relative importance of temperatures and other factors in determining geographic boundaries of seaweeds: experimental and phenological evidence. helgoländer meeresunters 42, 199�241. brouwer p. 1996. decomposition in situ of the sublittoral antarctic macroalga desmarestia anceps montagne. polar biology 16, 129�137. ceaza-met (center for advanced studies in arid zones, meteorology section) 2010. red meteorológica de sensores, chile. (network of meteo�sensors, chile). accessed on the internet at http://www.ceazamet.cl on february 2013. clarke a., meredith m.p., wallace m.i., brandon m.a. & thomas d.n. 2008. seasonal and interannual variability in temperature, chlorophyll and macronutrients in northern marguerite bay, antarctica. deep sea research part ii 55, 1988�2006. dayton p. 1985. ecology of kelp communities. annual review of ecology and systematics 16, 215�245. deregibus d., quartino m.l., campana g.l., momo f.r., wiencke c. & zacher k. 2015. photosynthetic light requirements and vertical distribution of macroalgae in newly ice-free areas in potter cove, south shetland islands, antarctica. polar biology 39, 153�166. dhargalkar v. 2004. effect of different temperature regimes on the chlorophyll a concentration in four species of antarctic macroalgae. seaweed research and utilization 26, 237�243. dring m.j. 1981. chromatic adaptation of photosynthesis in benthic marine algae: an examination of its ecological significance using a theoretical model. limnology and oceanography 26, 271�284. eggert a., visser r.j.w., van hasselt p.r. & breeman a.m. 2006. differences in acclimation potential of photosynthesis in seven isolates of the tropical to warm temperate macrophyte valonia utricularis (chlorophyta). phycologia 45, 546�556. falkowski p.g. & laroche j. 1991. acclimation to spectral irradiance in algae. journal of phycology 27, 8�14. gómez i. 2001. ecophysiology of antarctic macroalgae: effects of environmental light conditions on photosynthetic metabolism. revista chilena historia natural 74, 251�271. gómez i. & wiencke c. 1996. photosynthesis, dark respiration and pigment contents of gametophytes and sporophytes of the antarctic brown alga desmarestia menziesii. botanica marina 39, 149�158. gómez i. & wiencke c. 1997. seasonal growth and photosynthetic performance of the antarctic macroalga desmarestia menziesii (phaeophyceae) cultivated under fluctuating antarctic daylengths. botanica acta 110, 25�31. gómez i., weykam g., klöser h. & wiencke c. 1997. photosynthetic light requirements, metabolic carbon balance and zonation of sublittoral macroalgae from king pigment composition in desmarestia species a. mansilla et al. 8 (page number not for citation purpose) citation: polar research 2016, 35, 29383, http://dx.doi.org/10.3402/polar.v35.29383 http://www.ceazamet.cl http://www.polarresearch.net/index.php/polar/article/view/29383 http://dx.doi.org/10.3402/polar.v35.29383 george island (antarctica). marine ecology progress series 148, 281�293. guiry m. & guiry g. 2014. algaebase. accessed on the internet at http://www.algaebase.org on 22 december 2014. häder d.p. & häder m. 1989. effects of solar uv-b irradiation on photomovement and motility in photosynthetic and colourless flagellates. environmental and experimental botany 29, 273�282. huovinen p., gómez i. & lovengreen c. 2006. a five-year study of solar ultraviolet radiation in southern chile (398 s): potential impact on physiology of coastal marine algae? photochemistry and photobiology 82, 515�522. johansson g. & snoeijs p. 2002. macroalgal photosynthetic responses to light in relation to thallus morphology and depth zonation. marine ecology progress series 244, 63�72. kirst g. & wiencke c. 1995. ecophysiology of polar algae. journal of phycology 31, 181�199. lamb i. & zimmerman m.h. 1977. benthic marine algae of the antarctic peninsula. washington, dc: american geophysical union. lamouroux j.v.f. 1813. essai sur les genres de la famille des thalassiophytes non articulées. (essay on the genera of the non-articulated thalassiophytes family.) annales du muséum d’histoire naturelle, paris 20, 21�47, 115�139, 267�293, pls 7�13. machale k.m., davison i.r. & falkowski p.g. 1996. thermal acclimation and photoacclimation of photosynthesis in the brown alga laminaria saccharina. plant, cell & environment 19, 1005�1016. mansilla a. & alveal k. 2004. generalidades sobre las macroalgas. (overview of macroalgae.) in c. werlinger (ed.): biologı́a marina y oceanografı́a: conceptos y procesos. (marine biology and oceanography: concepts and processes.) pp. 349�362. concepción: trama impresores s.a. moe r.l. & silva p.c. 1989. desmarestia antarctica (desmarestiales, phaeophyceae), a new ligulate antarctic species with an endophytic gametophyte. plant systematics and evolution 164, 273�283. motten a.f. 1995. diversity of photosynthetic pigments. in c.a. goldman (ed.): tested studies for laboratory teaching. proceedings of the workshop/conference of the association for biology laboratory education (able). vol. 16. pp. 81�98. new haven, ct: association for biology laboratory education. navarro n.p., mansilla a. & plastino e. 2009. iridaea cordata (gigartinales, rhodophyta): responses to artificial uvb radiation. journal of applied phycology 22, 385�394. nygård c. & dring m.j. 2008. influence of salinity, temperature, dissolved inorganic carbon and nutrient concentration on the photosynthesis and growth of fucus vesiculosus from the baltic and irish seas. european journal of phycology 43, 253�262. palma e.d., matano r.p. & piola a.r. 2008. a numerical study of the southwestern atlantic shelf circulation: stratified ocean response to local and offshore forcing. journal of geophysical research*oceans 113, c11010, doi: 10.1029/ 2007jc004720. peckol p. & ramus j. 1988. abundances and physiological properties of deep-water seaweeds from carolina outer continental shelf. journal of experimental marine biology and ecology 115, 25�39. peters a.f., oppen m.j., wiencke c., stam w.t. & olsen j.l. 1997. phylogeny and historical ecology of the desmarestiaceae (phaeophyceae) support a southern hemisphere origin. journal of phycology 33, 294�309. plastino e. & mansilla a. 2004. luz y fotosı́ntesis. (light and photosynthesis.) in c. werlinger (ed.): biologı́a marina y oceanografı́a: conceptos y procesos. (marine biology and oceanography: concepts and processes.) pp. 229�252. concepción: trama impresores s.a. quartino m., kloeser h., schloss i. & wiencke c. 2001. biomass and associations of benthic marine macroalgae from the inner potter cove (king george island, antarctica) related to depth and substrate. polar biology 24, 349�355. quartino m., zaixso h.e. & boraso de zaixso a.l. 2005. biological and environmental characterization of marine macroalgal assemblages in potter cove, south shetland islands, antarctica. botanica marina 48, 187�197. ramus j. 1978. seaweed anatomy and photosynthetic performance: the ecological significance of light guides, heterogenous absorption and multiple scatter. journal of phycology 14, 352�362. ramus j. 1981. the capture and transduction of light energy. in c.s. lobban, m.j. wynne (eds.): the biology of seaweeds. pp. 458�492. berkely, ca: university of california press. ramus j. 1983. a physiological test of the theory of complementary chromatic adaptation. ii. brown, green and red seaweeds. journal of phycology 19, 173�178. rautenberger r., mansilla a., gómez i., wiencke c. & bischof k. 2009. photosynthetic responses to uv-radiation of intertidal macroalgae from the strait of magellan (chile). revista chilena de historia natural 82, 43�61. rautenberger r., wiencke c. & bischof k. 2013. acclimation to uv radiation and antioxidative defence in the endemic antarctic brown macroalga desmarestia anceps along a depth gradient. polar biology 36, 1779�1789. reid j.l. 1989. on the total geostrophic circulation of the south atlantic ocean: flow patterns, tracers, and transports. progress in oceanography 23, 149�244. santana a., porter c., butorovic n. & olave c. 2006. primeros antecedentes climatológicos de estaciones automáticas (aws) en el canal beagle, magallanes, chile. (first climatic registry by automatic weather stations [aws] in beagle channel, magallanes, chile.) anales del instituto de la patagonia 34, 5�20. seely g.r., duncan m.j. & vidiver w.e. 1972. preparative and analytical extraction of pigments from brown algae with dimethyl sulfoxide. marine biology 12, 184�188. setchell w.a. & gardner n.l. 1925. the marine algae of the pacific coast of north america. university of california publications in botany 8, 383�898. silva n. & calvete c. 2002. caracterı́sticas oceanográficas fı́sicas y quı́micas de canales australes chilenos entre el golfo a. mansilla et al. pigment composition in desmarestia species citation: polar research 2016, 35, 29383, http://dx.doi.org/10.3402/polar.v35.29383 9 (page number not for citation purpose) http://www.algaebase.org http://www.polarresearch.net/index.php/polar/article/view/29383 http://dx.doi.org/10.3402/polar.v35.29383 de penas y el estrecho de magallanes. cimar dos fiordos. (physical and chemical oceanographic characteristics of southern chilean channels between the gulf of penas and the strait of magellan. cimar two fjords.) ciencia y tecnologia del mar 25, 23�88. smith w.o. jr. & comiso j.c. 2008. the influence of sea ice on primary production in the southern ocean: a satellite perspective. journal of geophysical research 113, c05s93. statsoft. inc. 2004. statistica (data analysis software system) version 7.1. accessed on the internet at www.statsoft.com/ products/statistica/ in june�november 2014. torres r., silva n., reid b. & frangopulos m. 2014. silicic acid enrichment of subantarctic surface water from continental inputs along the patagonian archipelago interior sea (41�56 s). progress in oceanography 129, 50�61. valdenegro a. & silva n. 2003. caracterización oceanográfica fı́sica y quı́mica de la zona de canales y fiordos australes de chile entre el estrecho de magellan y cabo de hornos. cimar tres fiordos. (oceanographic physical and chemical characterization of the area of channels and fjords of chile between the strait of magellan and cape horn. cimar three fjords.) ciencia y tecnologı́a marina 26, 19�60. van den hoek v.d.c. 1982. the distribution of benthic marine algae in relation to the temperature regulation of their life histories. biological journal of the linnean society 18, 81�144. wiencke c. 1990. seasonality of brown macroalgae from antarctica*a long-term culture study under fluctuating antarctic daylengths. polar biology 10, 589�600. wiencke c., clayton m.n., gómez i., iken k., lüder u.h., amsler c.d., karsten u., hanelt d., bischof k. & dunton k. 2006. life strategy, ecophysiology and ecology of seaweeds in polar waters. reviews in environmental science and biotechnology 6, 95�126. wiencke c., clayton m.n. & schulz d. 1995. life history, reproductive morphology and development of the antarctic brown alga desmarestia menziesii j. agardh. botanica acta 108, 201�208. wiencke c., roleda m.y., gruber a., clayton m.n. & bischof k. 2006. susceptibility of zoospores to uv radiation determines upper depth distribution limit of arctic kelps: evidence through field experiments. journal of ecology 94, 455�463. wiencke c., stolpe u. & lehmann h. 1991. morphogenesis of the brown alga desmarestia antarctica cultivated under seasonally fluctuating antarctic daylengths. serie scientifica chilean antarctic institute (inach) 41, 65�78. wu h., jiang h., liu c. & deng y. 2015. growth, pigment composition, chlorophyll fluorescence and antioxidant defenses in the red alga gracilaria lemaneiformis (gracilariales, rhodophyta) under light stress. south african journal of botany 100, 27�32. yang e.c., peters a.f., kawai h., stern r., hanyuda t., bárbara i., müller d.g., strittmatter m., prud’homme van reine w.f. & küpper f.c. 2014. ligulate desmarestia (desmarestiales, phaeophyceae) revisited: d. japonica sp. nov. and d. dudresnayi differ from d. ligulata. journal of phycology 50, 149�166. yokoya n.s., necchi o., martins a.p., gonzalez s.f. & plastino e.m. 2007. growth responses and photosynthetic characteristics of wild and phycoerythrin-deficient strains of hypnea musciformis (rhodophyta). journal of applied phycology 19, 197�205. zacher k., roleda m.y., wulff a., hanelt d. & wiencke c. 2009. responses of antarctic iridaea cordata (rhodophyta) tetraspores exposed to ultraviolet radiation. psychological research 57, 186�193. zinova a.d. 1959. o dvukh burykh vodoroslyakh iz antarktiki: phyllogigas i himantothallus. (on two brown algae from antarctica: phyllogigas and himantothallus.) botanicheski zhurnal (botanical journal) 44, 372�379. pigment composition in desmarestia species a. mansilla et al. 10 (page number not for citation purpose) citation: polar research 2016, 35, 29383, http://dx.doi.org/10.3402/polar.v35.29383 http://www.statsoft.com/products/statistica/ http://www.statsoft.com/products/statistica/ http://www.polarresearch.net/index.php/polar/article/view/29383 http://dx.doi.org/10.3402/polar.v35.29383 bjerke.indd 127bjerke 2001: polar research 20(2), 127–128 dear organizers, ladies and gentlemen, i am very pleased to be here today to commemorate an outstanding norwegian scientist, and one of the great events in norwegian research history. the previous speakers have given us interesting views of the maud expedition, which was concluded 75 years ago, and of harald ulrik sverdrup’s scientific influence as one of the founders of modern oceanography. fridtjof nansen pushed strongly for the maud expedition after amundsen misled him in 1910 and went to the antarctic instead of the arctic with fram. almost 10 years after his departure for the south pole, amundsen was able to fulfil his promise to nansen, and set off with maud to the polar basin, with sverdrup onboard as the leading scientist. in this way, sverdrup followed directly in nansen’s scientific footsteps i doubt that sverdrup ever considered himself a climate scientist. at that time, climate was not considered a research theme of its own. but it is clear that both nansen and sverdrup were aware of the polar basin’s significant influence on global climate. as far back as in 1902, nansen wrote: “it is evident that the oceanographical conditions of the north polar basin have much influence upon the climate, and it is equally evident that changes in the condition of circulation would greatly change the climate conditions”. nansen’s words have been proven true: the scientific achievements of the 20th century have allowed us to understand many of the details of this complex causeand-effect relationships between climate, ocean and atmosphere. climate is the average weather over a long time period. we need long-time series of climate parameters in order to document changes in climate and explain their causes. such time-series can only be achieved by observational methods or by studying historic and prehistoric records. on land and in the atmosphere we have fairly good observational data for more than 100 years. data are more sparse for the oceans; the seven years of data collected during the maud expedition were an exceptional contribution to the establishment of long time records. though our observational data for the oceans are not as good as for the land and atmosphere, scientists have recognized the importance of ocean prosesses in climate change. we now realize that processes in the polar basin and its rim oceans have great influence on the influx of warm water to the north atlantic, which is the factor that 75 years evolution in our climate research minister of the environment, siri bjerke fram museum, bygdøy, norway 21 september 2000 invited keynote address 128 75 years evolution in our climate research makes western and northern europe a relatively comfortable place to live for humans. but these processes and how they change with time are not well understood due to lack of long time series. determining the human impact on climate is a costly challenge that must be taken up. research in the northern and southern extremities of our planet will be vital in this endeavour. the polar regions can be described as “early warning” areas. glaciers and sediments in polar areas provide us with historical and current information that cannot be found elsewhere. scientists tell us that rapid changes can be expected—within the lifetime of a person! this gives us a whole new perspective, and forces politicians worldwide to take action. because climate change is an issue that cannot be more international, only by joining forces can we effectively confront this development. consequently, i heartily welcome the initiative taken by the organizers of the sverdrup symposium, which is to be held the next couple of days at the polar environmental centre in tromsø. one important purpose of the symposium is to promote the joining of forces by proposing an international observation programme of the geophysical processes that are so important to the large-scale ocean circulation in the north atlantic. i can assure you that norway will support such an initiative. scientists conclude with high certainty that the world wide temperature increase we have observed the last 20 years is caused by humans. in the arctic, the sea ice is disappearing, precipitation is increasing, in some regions the average air temperature has increased by several degrees. we have observed that winter precipitation is increasing along the western coast of norway and in northern norway, as predicted by the regional climate model recently developed in norway. last year eight people were killed as a direct result of the enormous quantity of snow in the county of troms in northern norway. infrastructure was damaged and transportation systems were closed down for weeks. scientists predict that such conditions will prevail in the years to come, and there is growing political concern about the situation. i am a politician, not a scientist. to take informed political action, my colleagues worldwide and i need high quality scientific knowledge about climate change, its causes and consequences in the natural world and on human society. the changes we have seen in recent years and the increasing impacts on the society are the reasons why governments of the eight arctic states have taken an initiative to conduct a joint arctic climate impact assessment (acia). at a ministerial meeting in alaska next month, ministers from all these countries will approve the acia implementation plan. after four years, acia will deliver a scientific assessment of the societal consequences of climate change in the arctic, and recommend actions to political leaders. i strongly support this initiative and will assure all of you that the political recommendations for actions will be given serious consideration. por_012.fm 90 polar research 26 (2007) 90 © 2007 the authors erratum the article by fuglei & goldman, ‘hanna marie resvoll-holmsen: a pioneer in svalbard’, published in vol. 25, no. 1 (2006, pp. 1–13) mistakenly referred on page 6 to a 1908 expedition to svalbard financed by prince albert i of monaco. in fact that 1908 expedition, which was led by adolf hoel, was financed by the university of oslo. doi:10.3402/polar.v33.20403 r e s e a r c h / r e v i e w a r t i c l e distribution of total alkalinity and ph in the ross sea (antarctica) waters during austral summer 2008 paola rivaro,1 roberta messa,1 carmela ianni,1 emanuele magi1 & giorgio budillon2 1 department of chemistry and industrial chemistry, university of genoa, via dodecaneso 31, it-16146 genova, italy 2 department of environmental sciences, centro direzionale, parthenope university, isola c4 it-80143 napoli, italy keywords total alkalinity; ph; saturation state; terra nova bay polynya; ross sea. correspondence paola rivaro, department of chemistry and industrial chemistry, university of genoa, via dodecaneso 31, it-16146 genova italy. e-mail: rivaro@chimica.unige.it abstract measurements of total alkalinity (at) and ph were made in the ross sea in january�february 2008 in order to characterize the carbonate system in the ross sea and to evaluate the variability associated with different water masses. the main water masses of the ross sea, antarctic surface water, high salinity shelf water (hssw), deep ice shelf water, circumpolar deep water (cdw) and antarctic bottom water, were identified on the basis of the physical and chemical data. in particular, the at ranged between 2275 and 2374 mmol kg �1 with the lowest values in the surface waters (2275�2346 mmol kg�1), where the influence of the sea-ice melting and of the variability of the physical properties was significant. in the deep layers of the water column, the at maxima were measured in correspondence to the preferential pathways of the spreading hssw. the ph had variable values in the surface layer (7.890�8.033) with the highest values in terra nova bay and ross sea polynyas. a low ph (7.96990.025) traced the intrusion of the cdw in the ross sea shelf area. all samples revealed waters that were oversaturated with respect to both calcite and aragonite, but near corrosive levels of aragonite saturation state (v ca. 1.1�1.2) were associated with the entrainment of cdw over the slope. aragonite undersaturation is of particular concern for the zooplankton species comprising to calcifying organisms such as pteropods. the partial pressure of co2 at the sea surface was undersaturated with respect to the atmospheric value, particularly in terra nova bay and the ross sea polynyas, but a large variability in the sea�air co2 fluxes was observed associated with different responses in the strength of the biological and physical processes. the ross sea is an important site of deep water production (orsi et al. 1999; gordon, padman et al. 2009) and one of the most biologically productive regions in the southern ocean (garrison et al. 2003; smith et al. 2003; arrigo & van dijken 2004). for these reasons, the ross sea plays a role in the global carbon budget behaving as an atmospheric carbon dioxide (co2) sink. the magnitude of this sink depends on different environmental conditions and physical and biological processes. physical processes such as the formation of antarctic bottom water (aabw), which is an essential component of the global thermohaline circulation, the upwelling of the circumpolar deep water (cdw) near the margin of the ross sea continental shelves and the pack-ice coverage can largely influence the sea�air exchange of co2. the export of new deep and bottom waters produced over the continental margins of the ross sea, by the mixing of shelf waters (sws) and the cdw, contributes significantly to the total ventilation of the deep southern ocean (orsi & wiederwohl 2009); it may play an important role in the sequestration of anthropogenic co2 transferring dissolved co2 into the deep ocean (caldeira & duffy 2000; sabine et al. 2004; sandrini et al. 2007). the oceanography of the ross sea is largely affected by the presence of polynyas (areas where the sea surface is kept free from sea ice even during the winter). in these polar research 2014. # 2014 p. rivaro et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 areas, the surface seawater shows temperatures near the freezing point and is directly exposed to a large negative (sea�air) heat flux. these conditions yield fast formation of new sea ice (polynyas are often referred to as ‘‘sea-ice factories’’) and the rejection of brine. brine-enriched water descends, because it is dense, allowing the injection of dissolved oxygen into the deeper layers, since it has originated from surface waters. the terra nova bay polynya (tnbp) is a coastal latent heat polynya located in the western ross sea (fig. 1); it is considered as the main source of high salinity shelf water (hssw), which is the densest sw of the ross sea, and*in turn*a fundamental component of the aabw in this region (jacobs et al. 1985; parish & bromwich 1989; bromwich et al. 1990; budillon & spezie 2000; fusco et al. 2009). the seasonal ice coverage strongly impacts the cycling of chemical species and biological processes. significant sea-ice coverage restricts co2 sea�air exchange during winter in the ross sea and thus limits the equilibration of the antarctic surface water (aasw) with the overlying atmosphere. as a result of the heterotrophic activities, the aasw is supersaturated with co2 and undersaturated in dissolved oxygen (o2) (sweeney 2003). melting of pack-ice and warming of aasw are responsible for water column stratification, which favours the phytoplankton bloom in summer. phytoplankton photosynthetic activities cause a reduction in the sea-surface partial pressure of co2 (pco2) and an increase of o2. differences in the strength of the water column stratification, in the upper mixed layer (uml) and in the algal population can account for significant differences of the pco2 drawdown. in particular, the co2 drawdown measured for diatoms is much lower than that measured for phaeocystis antarctica (arrigo et al. 1999; feng et al. 2010). the sea-ice extension and disappearance, and consequently the sea�air exchange of co2 can also be impacted by large-scale climate signals (e.g., el niño southern oscillation, southern annular mode), as well as by large icebergs calving off the face of the ross ice shelf (arrigo & van dijke 2004; massolo et al. 2009). recently, fine-scale variability in pco2, in the ross sea polynya (rsp), located in the south-western ross sea at about 75.518s, 179.218e, has been documented, fig. 1 distribution of the conductivity�temperature�depth casts sampled for the carbonate system variables during italian national antarctic research program austral summer cruise 2008. the insert shows the ross sea inside the southern ocean. the areas of the ross sea investigated in this study are labelled: terra nova bay polynya (tnbp), ross sea polynya (rsp), drygalski trough (dt), glomar challenger trough (gct). the italian research station mario zucchelli (mzs) is shown. distribution of total alkalinity and ph in the ross sea p. rivaro et al. 2 (page number not for citation purpose) citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 exhibiting significant differences between the early spring and summer. this variability was also found to be coupled to the heterogeneity in underlying physical and biological variables (e.g., sea-ice cover and chlorophyll-a) (tortell et al. 2011). in 2008, we were able to obtain measurements of the ross sea co2 system (ph and total alkalinity [at]) for the sea surface and water column during the summer season within the framework of the italian national antarctic research program (pnra) oceanographic survey. this paper aims at characterizing the carbonate system in the ross sea and at evaluating the variability associated with different water masses. moreover, it extends previous analyses carried out by pnra by presenting new data that aids in understanding the co2 system distribution parameters. we will focus on the influence of the sea ice and of the physical variables on the inorganic carbon parameters distribution in the aasw, on the co2 air�sea fluxes and on the role of the main water masses in the distribution of inorganic carbon in the intermediate and deep layers, with particular regard for the intruding cdw in its contribution to the acidification of the ross sea. methods sampling the sampling took place from 25 january to 4 february 2008, as part of the pnra oceanographic survey of the ross sea. a total of 60 seawater samples were collected for measurements of ph and at. stations a, h1, l, d and b are located on the continental shelf, stations h2, h3 and g over the slope, and station p offshore (fig. 1). information on the stations sampled is in table 1. conductivity�temperature�depth (ctd) casts were performed using an sbe 911plus probe with double temperature, conductivity and oxygen sensors coupled to a sbe 32 carousel water sampler (sea-bird electronics, bellevue, wa). the ctd was flushed at a constant rate, always below 1m s �1 . calibration of temperature and conductivity sensors was performed before and after the cruise. hydrological data were corrected and processed according to international procedures (unesco 1988). standard algorithms (fofonoff & millard 1983) were used to compute derived quantities such as potential temperature, salinity and potential density anomaly. the water samples that were used for the ph and the at analyses were collected from 12 l niskin bottles and put into 500-ml borosilicate glass bottles, using the standard operating procedures described in the doe handbook (doe 2007a). the water samples were poisoned with saturated hgcl2 solution to stop biological activity from altering the carbon distributions in the sample containers before analysis. samples were stored in dark, cold (�48c) conditions and analysed at the department of chemistry and industrial chemistry at the university of genoa. the analyses were performed within four months of sampling. seawater at and ph measurements the at (mmol kg �1 seawater) was measured using a potentiometric titration system with an 806 exchange unit (metrohm, herisau, switzerland) and a 702 sm titrino dosimat (metrohm, herisau, switzerland). we followed the methods described in the doe handbook (doe 2007a), which was adapted to our instrumentation (rivaro, messa et al. 2010). placed in an open cell, 165 g of seawater was titrated with a solution of hydrochloric acid (hcl) in a two-stage titration. the sample, maintained at constant temperature (2590.18c) using a thermostatic water bath, was first acidified to a ph of between 3.5 and 4.0 with a single aliquot of titrant (3.7 ml of hcl 0.1 m), then stirred for 10 min to allow for the liberation of the co2 that was evolved. the titration continued until a ph of about 3.0 was reached. the ionic strength of the hcl solution was adjusted with nacl in order to be similar to that of the samples (salinity range 33.5�34.8). the progress of the titration was monitored using a ph glass electrode/ reference electrode cell, and the at was computed from the titrant volume and potential difference measurements using a non-linear least-squares approach similar to that proposed in the doe handbook (doe 1994). the precision was computed from three replicate analyses of one sample at least daily and was determined to 93 mmol kg�1 (90.1%). routine analyses of certified reference materials (batch no. 79, provided by a. g. dickson, scripps institution of oceanography) ensured the accuracy of the measurements, which was 93 mmol kg�1. the ph was expressed in the ph total scale, (i.e., [h � ] as moles per kilogram of seawater, pht) and it was table 1 dates, coordinates and depths of the stations sampled during the austral summer 2008 in the ross sea. station sampling date latitude longitude bottom depth (m) a 30 jan 2008 76841.821? s 169802.143? e 813 h1 28 jan 2008 75857.559? s 177818.891? w 621 h2 29 jan 2008 75809.889? s 176814.220? w 787 h3 29 jan 2008 75802.618? s 176834.388? w 1068 l 26 jan 2008 74844.742? s 164810.816? e 205 d 25 jan 2008 75807.994? s 164833.289? e 1116 b 27 jan 2008 73859.158? s 175803.065? e 578 g 27 jan 2008 72823.147? s 173803.393? e 523 p 04 feb 2008 70853.212? s 172800.751? e 2315 p. rivaro et al. distribution of total alkalinity and ph in the ross sea citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 determined using a potentiometric method that employed a combination glass/reference electrode with a negative temperature coefficient thermistor. the tris(hydroxymethyl)aminomethane (tris) buffer used to standardize the ph electrode was prepared according to the doe handbook (doe 2007b). the salinity of the tris buffer was 35. both the tris buffer and the seawater samples were brought to the same temperature (2590.18c) using a thermostatic water bath, before the measurements were conducted. the accuracy of the ph measure is strongly dependent on the composition of the tris buffer solution, but no certified material is currently available. consequently, this figure of merit was not determined. the precision of the ph measurement was 90.007 units and was evaluated by repeated analysis of the at certified material. the pht measures at 258c were then recalculated at in situ temperature and pressure conditions (phin situ). pco2 and ct calculation at, pht, salinity and temperature were used as input parameters in the co2-chemical speciation model to calculate pco2 (co2sys program [pierrot et al. 2006]). we used the co2-system dissociation constants (k*1 and k*2) estimated by roy et al. (1993), as a recent paper showed these constants to be the most suitable for cold and fresher surface waters (chierici & fransson 2009). we used the dickson constant for the hso�4 (1990). following millero (2007), the estimated probable errors in the calculated parameters of the carbonate system using at and pht data as input measurements are 94 mmol kg �1 and 92 matm, for both ct and pco2, respectively. sea�air exchange of co2 and co2 flux formulation the most direct method to estimate the uptake of atmospheric co2 by the oceans is by determining the air�sea flux from values of the pco2 in the sea surface and the overlying atmosphere. the net sea�air co2 exchange flux (f, mmol m �2 d �1 ) is calculated using the formula: f ¼ ksðdpco2þ; (1) where k is the co2 gas transfer velocity (cm h �1 ), s is the solubility of co2 (mol kg �1 atm �1 ) and dpco2 is the difference between the pco2 of the seawater (pco2sw) and the air (pco2atm). negative dpco2 values indicate absorption of the gas by the sea surface, while positive values correspond to the release of the gas into the atmosphere. therefore, the sea�air flux of co2 is dependent on the difference of co2 concentration between sea surface and atmosphere (dpco2, matm) and proportional to the wind speed. the dpco2 values were calculated as the difference between the pco2 in seawater, calculated from our at and ph measurements, and the atmospheric co2 mean value of 382 matm available from the south pole observatory (http://www.esrl.noaa.gov/gmd/obop/spo/). the atmospheric pco2 was corrected to 100% humidity at in situ sea-surface temperature (sst) and salinity (sss). correction for the water vapour pressure was carried out using the equations of weiss & price (1980). the water vapour pressure values were then used to correct p(co2) dry to 100% humidity using the standard formula as given in doe (1994) as standard operational procedure 5. the solubility coefficient s was calculated in each sample as a function of temperature (t) and salinity (s), using weiss (1974). the gas transfer velocity k, depends on the wind speed u. we applied the wanninkhof formulation (1992), where kco2 �0.31u 2 (660/scco2) 0.5 for instant wind speed measures or kco2 �0.39u 2 (660/scco2) 0.5 for averaged wind speed. we also applied the wanninkhof & mcgillis (1999) formulation where kco2 �0.0283u 3 (660/ scco2) 0.5 . scco2 is the schmidt number for co2. we used our ship-based wind speed data at 10m height and monthly data provided by the european centre for medium-range weather forecast (ecmwf) with a spatial resolution of 18�18 for the grid points. the wind speeds used in this study are reported in table 2. results physical characteristics of the water masses different water masses were identified in the sampled stations using potential temperature (u), salinity (s) and neutral density (gn) values (jackett & mcdougall 1997) (fig. 2; table 3). following whitworth et al. (1998), orsi et al. (1999) and orsi & wiederwohl (2009) we used the gn 28.00 kg m�3 and 28.27 kg m�3 values to separate the table 2 wind speed used for co2 flux calculation in this study. station instantaneous shipboard wind speed (ms �1 ) monthly ecmwfa wind speed (ms �1 ) a 4.190.8 4.393.4 h1 6.291.2 7.393.0 h2 1.590.3 7.293.2 h3 9.391.8 7.193.2 l 7.791.5 4.492.8 d 9.891.9 4.892.8 b 4.690.9 7.293.3 g 3.690.7 7.693.7 p 3.190.6 9.294.9 a european centre for medium-range weather forecast. distribution of total alkalinity and ph in the ross sea p. rivaro et al. 4 (page number not for citation purpose) citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 http://www.esrl.noaa.gov/gmd/obop/spo/ http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 cdw from the aasw and from the densest water masses below, respectively. the six water masses that were identified are described below. the aasw is characterized by a gn lower than 27.70 kg m �3 and by a wide range of temperatures (��1.08c) and salinities (b34.20) due to its interaction with atmosphere and ice production and melting. following the approach introduced by mitchell & holm-hansen (1991) an increase of in situ density �0.05 kg m �3 over 5 m depth interval was the criterion used to establish the depth of uml in the aaws. a thin uml was found in tnbp (10�15 m), whereas it became thicker in the other stations, ranging from 23 m (station p) to 34 m (station h3). our values are in agreement with those reported for the same areas by massolo et al. (2009). the cdw is characterized by a gn within the range of 28.00�28.27 kg m�3, with a sharp core showing the temperature maximum (�1.08c). the modified circumpolar deep water (mcdw), which is the cdw entering in the ross sea and isopycnally mixed with local water, is characterized by the same density range as cdw, but with lower temperatures. the deep ice shelf water (disw) is characterized by potential temperature below the surface freezing point (sfp) and present in front of the ross ice shelf between 1608w and 1808 (orsi & whiederwohl 2009). the hssw is characterized by a salinity maximum greater than 34.70, temperature near the sfp and by a gn greater than 28.60 kg m �3 . the aabw is characterized always by a gn greater than 28.27 kg m �3 and with potential temperature below 08c, which is found offshore the 700 m on the slope. distribution of the inorganic c parameters (at, ph, ct and pco2) the at measured in our samples ranged between 2275 and 2374 mmol kg�1 and had good agreement with previous data collected in the ross sea (sandrini et al. 2007). fig. 2 potential temperature salinity (u/s) plot for the sampled stations. major water masses are abbreviated as follows: antarctic surface water (aasw), circumpolar deep water (cdw) modified circumpolar deep water (mcdw), high salinity shelf water (hssw), deep ice shelf water (disw) and antarctic bottom water (aabw). table 3 average values of physical properties for water masses found in the ross sea in 2008 survey. water mass temperature (8c) salinity neutral density (kg m �3 ) aasw a ��1.0 b34.20 b27.70 cdw b �1.0 34.60bsb34.75 28.00bgn b28.27 mcdw c �1.2btb0.0 34.30bsb34.60 27.90bgn b28.20 hssw d ca. tsfp g �34.70 �28.6 disw e btsfp �34.45 �28.4 aabwf �1.5btb�0.5 �34.60 �28.27 a antarctic surface water. b circumpolar deep water. c modified circumpolar deep water. dhigh salinity shelf water. edeep ice shelf water. fantarctic bottom water. g surface freezing point. p. rivaro et al. distribution of total alkalinity and ph in the ross sea citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 figure 3 shows the at as a function of depth at all of the stations. generally, the at profiles in the continental shelf stations had the lowest values in surface water (from 2275 to 2346 mmol kg�1), an increasing gradient reaching the maximum values (from 2343 to 2374 mmol kg �1 ) at ca. 500�700 m, and then lower values at deeper depths. the station p, sampled offshore, showed an increase in at values from ca. 1700 m to the deepest sampled depth (ca. 2300 m). at the surface, the highest values were measured at stations l, d and a (2328, 2334 and 2346 mmol kg�1, respectively). pair-wise pearson correlation coefficients were computed to examine the relationships between inorganic c parameters and hydrographic measurements. the at and the salinity were significantly and positively correlated (pearson’s r �0.86, number of samples �57), according to the following relationship: at¼ 68:14s�5:1804 mmol kg �1 (2) no significant correlation were found between at and u when the whole data set was considered. the relationship becomes significantly positive (r �0.62, number of samples 16) when surface and subsurface samples (i.e., 1�10 m depth) are considered, suggesting that the temperature could explain some of the observed at variability in the aasw. pht values recalculated at in situ temperature and pressure conditions (phin situ) ranged between 8.274 and 7.926. phin situ was significantly and negatively correlated to s (r� �0.71) when the whole data set was considered. there was no correlation between phin situ and either temperature or salinity when the 1�10 m depth samples were considered. the phin situ vertical distribution is shown in fig. 4. the phin situ has high and variable values in the surface layer (from 7.890 to 8.033 between 0 and ca. 100 m), then an abrupt drop with depth to approximately 100�400 m, followed by a slight increase and nearly constant values. at the surface, the lowest values were measured at stations h2, h3, g, b and p (8.10890.023), while stations d, l, a and h1 showed a higher variability and the highest ph values (8.18690.088). the same trend was observed in the subsurface layer too. an increasing gradient of the phin situ can be observed from the offshore to the ross sea shelf stations, particularly at intermediate depths around 300�500 m. the left-most profile in fig. 5 refers to station h3 sampled in the glomar challenger trough (gct; fig. 1), where the absolute phin situ minimum (7.950) was found in correspondence to the cdw intrusion. comparable values were measured at station h2, sampled as well as station h3 in the gct and at station p offshore the drygalski trough (dt; fig. 1), the other well-known intruding area of the cdw in the ross sea. the at, pht and the hydrographic data were used to calculate ct and pco2. the ct ranged from 2082 to 2263 mmol kg�1; generally the lowest values were measured at the surface, with the absolute minimum at station h1, while the highest were measured at intermediate depths (ca. 500 m) at stations d, p, g, h3 and b. the ct standard deviation in the aasw was higher than that fig. 3 vertical profiles of the total alkalinity at in all of the sampled stations. distribution of total alkalinity and ph in the ross sea p. rivaro et al. 6 (page number not for citation purpose) citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 of at (39 vs. 23 mmol kg �1 ), whereas in the intermediate and deep layers the standard deviations were comparable (6 vs. 5 mmol kg�1, as mean values). the computed pco2 ranged from 207 to 479 matm; the top of aasw (2�20 m) was undersaturated in co2 compared to calculated atmospheric values, particularly at stations l, d, a and h1, with pco2 varying between 207 and 338 matm. the maxima were recorded at intermediate depths (ca. 500 m) at stations p and h3. the range of both parameters is in agreement with those reported for the ross sea waters (sweeney 2003; sandrini et al. 2007). discussion influence of sea ice and physical variables on the inorganic carbon parameters distribution in the aasw the general vertical distribution of the inorganic carbon parameters (increasing for the at, the ct and the pco2 and decreasing for ph) is mainly due to the biological activities (primary production and respiration, biogenic carbonate precipitation and dissolution), and to the physical properties of the water masses together with the fig. 4 profiles of the phin situ in all of the sampled stations. fig. 5 dpco2 (pco2sw�pco2air) (matm) calculated at the surface respect to a 382 ppm pco2air. p. rivaro et al. distribution of total alkalinity and ph in the ross sea citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 circulation pattern along the whole water column. the aasw occupies the top of the water column. the large standard deviation of the physical and chemical properties of aasw compared to the other water masses was consistent with the high variability of the upper layer of the water column, from the surface down to a depth of more than 100 m, which is strongly influenced by sea� ice�atmosphere interactions and by biological activity particularly in the summer season (when the sampling was performed). processes such as melting and formation of sea ice can play an important role in controlling the aasw physical features and inorganic carbon chemistry. in 2008, during the cruise, the sea-ice coverage was minimal and in the ross sea wide open sea areas were present (see satellite images at http://www.usap.gov/videoclipsandmaps). solar heating and decreased salinity, due to pack-ice melting, were responsible for the formation of the shallow uml in the aasw. to evaluate any effect of the sea-ice melting on the at and ct distribution at the surface, following rivaro et al. (2011), we calculated the meltwater percentage (mw%), considering the difference between the salinity measured at the surface (smeas) and the salinity measured in the same station at greater depth (sdeep), which was not influenced by sea-ice dilution, assuming an average sea-ice salinity of 6 (ackley et al. 1979): mw% ¼ 1� s meas �6 s deep �6 ! �100: (3) in our study, sdeep depths were chosen on the basis of their gn values; that is, we chose samples collected below the gn 28.00 kg m�3, which is the lower boundary of the aasw (table 4). mw% ranged from 1.1 (station p) to 4.1 (station a); the stations sampled in the gct (h1, h2, h3) had ca. 3% mw, while stations l and d, sampled at tnbp had 1.2 and 1.8 mw%, respectively. the 2008 mw% fell into the range of values observed in 2006, which was considered as a standard year for sea-ice coverage in the ross sea shelf area (massolo et al. 2009). the highest mw% calculated for stations h1, h2, h3 was consistent with the sea-ice coverage shown by satellite maps before the sampling period, showing a higher pack-ice extension in the gct than in the polynya area. the mw% co-varied significantly and negatively with at (pearson’s r � �0.79, p �0.05) and ct (pearson’s r � �0.62, p �0.05). this is consistent with the fact that the distribution of surface at and ct is controlled by the factors that govern salinity. therefore, the addition of sea-ice meltwater, which has low salinity, results in a dilution of the at and ct. unlike ct, ph and pco2, photosynthesis and oxidation of organic matter have little direct influence on at (redfield et al. 1963). calcifying organisms can influence at and ct concentration, but it is well known that the phytoplankton in the southern ross sea is dominated by two taxa that are spatially distinct: fragilariopsis curta, a pennate diatom, dominating the coastal region, and p. antarctica, a colonial prymnesiophyte, dominating the south central region (smith & nelson 1985; smith et al. 1996; arrigo et al. 1999). both are not calcifying organisms and therefore they are not able to influence at and ct. gordon et al. (2000) also reported that at does not vary during the summer in the ross sea, suggesting that phytoplanktonic calcifying organisms are unimportant in the carbon cycle in this region. a correlation between the surface at and temperature values was found in our study, suggesting that the temperature could explain some of the at variability, consistent with the dependence found for surface waters of the world ocean. in particular, lee et al. (2006) proposed several relationships to estimate at from salinity and temperature surface measurements. we applied the relationship proposed for the southern ocean to our data set: at¼ 2305þ52:48ðsss�35þþ2:85ðsss�35þ 2 �0:49ðsst�20þþ0:086ðsst�20þ2; (4) where sss and sst are sea-surface salinity and temperature, respectively. this relationship gave poor results, because the analysis of the residual, which is a good measure of the accuracy of the predictivity of the curve fitting, was about 11 mmol kg �1 , higher than the accuracy of our measurements (3 mmol kg�1). afterwards, a new similar relationship that provided more accurate estimates of at from the measured sss and sst for the surface waters of the ross sea was found. to find the new relationship we used the surface samples collected during the 2003 climatic long term table 4 data used for melt water percentage (mw%) calculation. station smeas sdeep depth (m) sdeep corresponding gn (kg m �3 ) calculated mw% a 34.20 34.53 85 28.08 1.2 h1 33.59 34.45 250 28.01 3.0 h2 33.80 34.57 500 28.02 2.7 h3 33.90 34.71 420 28.05 2.8 l 33.53 34.70 75 28.64 4.1 d 34.19 34.71 100 28.66 1.8 b 34.08 34.501 110 28.07 1.5 g 34.14 34.59 230 28.05 1.6 p 34.07 34.39 180 28.01 1.1 distribution of total alkalinity and ph in the ross sea p. rivaro et al. 8 (page number not for citation purpose) citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 http://www.usap.gov/videoclipsandmaps http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 interaction for the mass-balance in antarctica (clima) cruise (n �82; sandrini et al. 2007). the results were: at¼ 2308 þ108:98ðsss�34þþ60:70ðsss�34þ 2 þð�6:91½sstþ1:30�þþ9:091ðsstþ1:30þ2 (5) equation 5 was then applied to our samples; the analysis of the residual was 4 mmol kg�1, confirming its validity for the ross sea and showing that we could estimate the at from sss and sst in the ross sea aasw with a precision comparable to our measurements. the variability of the phin situ in the surface layer can be ascribed primarily to biological production and vertical mixing. primary production increases the ph of seawater as a result of the displacement of the carbonate equilibrium related to co2 consumption, while the vertical mixing of the surface water with deeper water causes a decrease of the ph. the correlation between phin situ and s or u was not significant in the aasw samples, suggesting that physical variables do not have a strong direct influence on the distribution of this parameter at the surface, which is therefore mainly governed by biological processes. the phin situ was negatively and significantly correlated to ct, while it was not correlated with at. the highest values were observed in stations d, h1 and a, which coincided with low ct values (2161, 2082 and 2158 mmol kg�1, respectively) and a slightly higher at:ct ratio (1.09), suggesting that ct plays a more significant role in regulating ph than at. the exchanges of co2 with the atmosphere can result in a modification of ph as well, but this effect is weak over the short time scale that we investigated. sea-air co2 fluxes all pco2 values of the surface and subsurface waters (2�20m) were below atmospheric levels, particularly at stations l, d, a and h1, with pco2 varying between 207 and 338 matm. considerable variation was, however, observed spatially (table 5). consequently, the dpco2 (pco2sw�pco2air) was negative (from �44 to �175 matm), outlining that the ross sea was a potential sink for co2 during the sampling (fig. 5). in surface seawater the pco2 depends on sst, sss, ct and at concentrations. these determinants are influenced by several processes such as warming/cooling and biological activity (bellerby et al. 2004). even though the pco2 is influenced by the sst and sss, no relationship between pco2 and physical variables was found in our samples collected in the surface waters. this agrees with the results obtained by poisson et al. (1993) and metzl et al. (1999), who did not find a large-scale correlation between fco2 and sst in the southern ocean during the austral summer. laika et al. (2009) confirmed that biological effects dominate the temperature effect on the pco2 distribution, especially in the areas south of the polar frontal zone, from the permanent open ocean zone to the antarctica shelf areas. the ross sea is one of the most productive areas of the southern ocean. marginal ice zones and polynyas are often associated with high primary productivity, which is the result of higher light availability (due to the reduced sea-ice cover) and higher micronutrient availability (in particular, fe; tagliabue & arrigo 2006). the rsp (fig. 1) is the most productive polynya, but the tnbp, which is smaller than the rsp, is also important in terms of productivity (mangoni et al. 2004). the phytoplankton bloom develops later in the year at the tnbp compared to rsp and it is dominated by diatoms. phytoplankton abundance is maximal in late december, declines thereafter, but a secondary peak appears in mid-february (tremblay & smith 2007). in our survey, the highest pco2 drawdown was calculated in the tnbp and rsp and in station h1, which was sampled in a marginal ice area. unfortunately, we could not directly confirm the table 5 surface temperature, salinity, pco2 and dpco2 together with the mean values and the standard deviations calculated for the fluxes of co2. station t8c s pco2 (matm) dpco2 (matm) flux co2 a (mmol m�2d �1) flux co2 b (mmol m�2d �1) flux co2 c (mmol m�2d�1) a �0.151 34.20 251 �131 �2.890.5 �3.892.8 �1.290.9 h1 �1.566 33.59 207 �175 �9.091.7 �15.396.0 �8.293.2 h2 �1.65 33.80 296 �86 �0.390.1 �7.492.9 �3.991.5 h3 �1.745 33.90 338 �44 �5.090.8 �3.691.4 �1.990.7 l �0.309 33.53 216 �166 �12.792.4 �5.293.1 �1.791.0 d �0.863 34.19 258 �125 �15.492.9 �4.592.4 �1.690.9 b �0.752 34.08 304 �79 �2.290.4 �6.592.7 �3.491.4 g �0.989 34.14 328 �54 �0.990.1 �5.092.1 �2.891.2 p �1.155 34.07 309 �73 �0.990.1 �9.994.7 �6.693.1 a flux calculated following wanninkhof (1992), using kco2 �0.32u 2 (660/sc) 0.5 and instantaneous shipboard wind speed data. b flux calculated following wanninkhof (1992), using kco2 �0.39u 2 (660/sc)0.5 and monthly data provided by the european centre for medium-range weather forecast. cflux calculated following wanninkhof & mcgillis (1999), using kco2 �0.0283u 3 (660/sc) 0.5 and monthly data provided by the european centre for medium-range weather forecast. p. rivaro et al. distribution of total alkalinity and ph in the ross sea citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 phytoplanktonic drawdown on the pco2, distribution, because neither chlorophyll-a sampling nor fluorescence measurements were performed. nevertheless, primary productivity calculated from sea wifs data referred to the investigated period (available at http://giovanni. gsfc.nasa.gov) and the comparison with data collected in previous surveys allowed us to hypothesize that the phytoplanktonic drawdown made an important contribution in determining the pco2 in the upper aaws (bates et al. 1998; gordon et al. 2000; sweeney et al. 2000; takahashi et al. 2002; barbini et al. 2003; sweeney 2003; arrigo & van dijken 2007). in particular, barbini et al. (2003) correlated the phytoplanktonic bloom events with the high chlorophyll-a concentrations and low pco2 values measured in selected sites during the xvi italian expedition (austral summer 2000�01) such as tnbp (corresponding with stations d and l), the rsp near ross island (corresponding with station a), and in the central basin area (corresponding with station h) (fig. 1). conversely, high values of surface pco2 were encountered towards the northern margin of the ross sea shelf area above 738s latitude, in the offshore area near cape adare and cape hallet where stations g and p were sampled in our survey (fig. 1). other evidence corroborating the hypothesis that primary production was playing an important role in regulating co2 distribution in the ross sea during austral summer 2008, could come from our o2 measurements (data not shown). the o2 concentration was compared with oxygen saturation (calculated from s and t) and a disequilibrium in o2 was observed in tnbp and rsp. the undersaturation in co2 coincided with a supersaturation in o2, which could not be explained by a change in the hydrography. finally, the pco2 and the phin situ correlated negatively and significantly in the aasw, consisting with the increase of the ph due to primary production as a result of the displacement of the carbonate equilibrium related to co2 consumption. the sea�air fluxes of co2 were calculated (table 5). wind speed is the main driver of the air*sea flux, together with the dpco2. both wind speed data (shipboard and ecmwf data) used to calculate the kco2 showed a marked spatial variation (table 2), which greatly influenced the calculated co2 fluxes. since the relationship between u and kco2 is still a source of uncertainty, we have applied different formulations. as a consequence of the negative dpco2 values, the air*sea co2 fluxes were directed towards the water column and no upward co2 flux was calculated. significant variability in the co2 sea�air flux was observed, with mean values ranging from �0.3 to �15.4 mmol m�2 d�1. although the differences, resulting from the choice of exchange coefficient and the chosen non-linear relationships between wind speed and gas transfer velocity were large, our range is comparable to those calculated by bates et al. (1998) and sweeney et al. (2000), who used long-term average wind speeds. the large flux uncertainty comes from the error in dpco2, the errors in the scaling factor for the gas transfer rate formula and the wind speed variability. using shipboard wind data, the highest mean flux was calculated at station d, where high drawdown of co2 by biological activity was supposed. using ecmwf wind data (lower than shipboard data; table 2), the estimated flux resulted in being three times lower. when fluxes were calculated using the cubic relationship between wind speed and co2 flux, the sink observed at tnbp became even weaker. in any case, it is important to note that our estimates are a snapshot only, describing the situation that we found during our cruise so that the mean fluxes should only be taken as indicative; therefore, any extrapolation to a seasonal flux should be treated carefully. influence of water masses and circulation pattern on distribution of inorganic carbon parameters in ross sea shelf area on the basis of the thermohaline properties and gn values, several intermediate and deep-water masses were identified in this study. afterwards, the values of the chemical parameters were constrained by the physical values used to differentiate the local water masses. differently from aasw, the physical and chemical properties varied within a relatively narrow range. cdw is a relatively warm and salty water mass that originates in the antarctic circumpolar current (acc) and episodically intrudes into the ross sea on the shelf, forced by the curvature of the bathymetry (dinniman et al. 2003). on the shelf, isopycnal mixing with cold and low-salinity aasw rapidly attenuates the characteristics of the cdw offshore, producing mcdw (jacobs & giulivi 1999). cdw or mcdw is thought to be important to many processes, such as the formation of aabw (orsi et al. 1999; gordon, orsi et al. 2009; orsi & wiederwohl 2009), the dynamics of the rsp (reddy et al. 2007), and supplying much of the heat involved in the basal melting of the ross ice shelf (smethie & jacobs 2005). cdw contains low levels of o2 and high levels of nutrients (nitrate, no3, phosphate po4 and silicate si(oh)4) and of ct, as it has an older ventilation age compared to the recently formed sw (rivaro et al. 2004; sandrini et al. 2007; rivaro, massolo et al. 2010). the mid-depth (ca. 500 m) intrusion of the cdw and its modification in mcdw was traced over the shelf by the high u, ct and pco2 values (��0.88c, 225197 mmol kg�1 and 463914 matm, respectively) and by the distribution of total alkalinity and ph in the ross sea p. rivaro et al. 10 (page number not for citation purpose) citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 http://giovanni.gsfc.nasa.gov http://giovanni.gsfc.nasa.gov http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 low phin situ (7.96990.025), particularly at stations p and h3 (fig. 5). these stations were located along the slope in the two well documented sites of cdw intrusion in the ross sea shelf area, the dt and the gct, respectively (orsi & whiederwool 2009). the re-mineralization of organic matter consumes o2, further increasing the nutrient, ct and pco2 concentrations. the ph decreases due to the addition of co2 from the oxidation of organic carbon. the high ct and the low phin situ characterizing the cdw are consistent with the old ventilation time, the low o2 and the high nutrient values. for this last feature, the intrusion of cdw on the shelf could represent a source of nutrients for biological production. the hssw is defined by gn �28.60 kg m�3, s �34.70 and temperatures close to the sfp; it is formed along victoria land and mainly in the tnbp area by brine rejection during surface water freezing and the strong katabatic winds flowing down to the antarctic plateau (budillon & spezie 2000). the hssw spreads northward along the dt, where it reaches the shelf break and ventilates the deep ocean producing aabw. another branch moves southward beneath the ross ice shelf taking part in the production of the disw (jacobs et al. 1985). disw is defined by gn �28.40 kg m�3, salinity higher than 34.45 and temperatures close to the sfp. the disw core moves northward along the gct, reaching the shelf break near 758s close to the dateline meridian where it also mixes with the intruding cdw taking part in aabw production (budillon et al. 2003; rubino et al. 2003; smethie & jacobs 2005; budillon et al. 2006). both hssw and disw are characterized by high o2 concentrations (about 295 mm), reflecting the origin of aasw in the case of hssw and the contribution of glacial meltwater in the case of disw. the hssw was characterized by the at maxima (236796 mmol kg �1 ), measured in the entire water column below 100�200 m in the d and l stations in the layers deeper than 500 m in the a, h1, b and g stations, which were sampled in correspondence to the preferential pathways of the spreading hssw. the high correlation between at and s and the conservative behaviour justify the fact that the highest at values are found in the deeper layers of the water column measured at stations l and d sampled at tnbp, which is the main site of hssw production in the ross sea. the disw was identified by u and s values at intermediate depths (between 400 and 500 m) in h1, and it was characterized by lower at than the hssw (23419 4 mmol kg�1). this difference is due to the dilution effect produced by glacial meltwater addition in the disw production. therefore, the at adds some information to the chemical characterization of the water masses, being able to chemically trace the two water masses. the same feature is shown by ct too; that is, hssw has a ct higher than disw (225198 and 222893, respectively). taking into account that both sws take part in the ross sea aabw production, and the role played by aabw as a co2 sink we can suppose that the plume produced in the dt injects a higher ct into the deep ocean than the plume leaving the gct. according to the definition by orsi & wiederwohl (2009), the aabw lies on the slope at depth �700 m, it is always characterized by a gn greater than 28.27 kg m�3 and by ub08c. in our data set these characteristics were shown by the deepest layers (depth�1850 m) at station p only, sampled in the dt mouth. no aabw was identified in the samples collected in the gct, although this area is a well-known aabw production site as documented by several ctd and moored station measurements (smethie & jacobs 2005; budillon et al. 2011). in fact the deepest layers of station h3, (depth�700 m) do not have ub08c and gn �28.27 kg m�3 (fig. 2, table 3). for this reason, we cannot evaluate whether the aabw produced in the two regions of the ross sea contains different amounts of ct and as a consequence whether the plume produced in the dt injects a higher ct into the deep ocean than the plume leaving the gct. the precipitation or formation of solid caco3 in surface waters and the dissolution of solid caco3 in deep waters can be important in transferring co2 from surface to deep waters. the uptake of co2 by surface layers increases the concentration of h � , which lowers ph and, in changing the chemical equilibrium of the inorganic carbon system, reduces the concentration of co3 2� . carbonate ions are required by marine calcifying organisms such as plankton, shellfish and fish to produce calcium carbonate shells and skeletons. the saturation state of the seawater with respect to caco3 is expressed by the ratio x ¼ ½ca2þ�½co2�3 �=k 0 sp ; (6) where [ca 2� ][co3 2� ] is the ion product of the concentration of calcium and carbonate ions, and k?sp is the solubility product depending on in situ temperature, salinity and pressure and on the particular mineral phase (aragonite is approximately 50% more soluble than calcite [mucci 1983]). the values of [co3 2� ] and of v have been determined from at and ph, using the co2sys program. all of the samples were oversaturated with respect both to the calcite and to the aragonite, with the exception of the deepest layers (below 1600 m) of p station, which were undersaturated with respect to the aragonite. near corrosive levels of aragonite saturation state (varag) (v ca. 1.1�1.2) were found in correspondence to the entrainment of cdw both in the dt and in p. rivaro et al. distribution of total alkalinity and ph in the ross sea citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 the gct. our data are in agreement with varag and ph values and variability in the ross sea calculated by mcneil et al. (2010). it has been predicted that the southern ocean will become undersaturated with respect to aragonite by 2030 (mcneil & matear 2008). the onshore transport of cdw, whether sporadic and occurring only at specific locations, could accelerate the ross sea acidification process, with respect to these predictions. aragonite undersaturation is of particular concern for the zooplankton species comprising pteropods, which form aragonite shells. in fact, pteropods comprise up to one-quarter of the total zooplankton biomass in the ross sea (hopkins 1987). recently, manno et al. (2007) described the occurrence of initial dissolution of the aragonitic shells of the pteropod limacina helicina above the saturation depth in the tnbp area, while honjo (2004) reported pteropod shell degradation at a depth of 1 km and below south of the polar front zone. bednaršek et al. (2012) comparing the shell structure of specimens l. helicina, that were extracted live from the southern ocean, with samples from aragonitesupersaturated regions, found severe levels of shell dissolution in the southern ocean organisms. all of these results suggest that changes in carbonate chemistry in the water column are already occurring and that they could possibly have significant effects throughout the ross sea marine food web. conclusion given the role of the ross sea in the global carbon budget, better knowledge of its inorganic carbon properties is required. this work presents the distribution of at and ph based on the hydrochemical data collected in the ross sea shelf area during february 2008. our measurements represent a contribution to the current understanding of carbonate chemistry in the ross sea, and provide insights into the biogeochemical processes that are occurring and the potential changes which may be reasonably expected in the near future. the influence of the sea ice and of the physical properties of the seawater on the inorganic carbon parameters distribution in the aasw was observed. in the deep layers of the water column, the at maxima were measured in correspondence to the preferential pathways of the spreading hssw. moreover, the at which is strongly dependent on salinity allowed us to chemically trace the hssw and to distinguish it from disw. the ph was not significantly correlated to physical variables in the surface waters, where the ph variations are mainly governed by biological processes. at mid-depths (300�500 m) a decreasing ph gradient was observed from the shelf area to offshore, in correspondence with the cdw intrusion, where near corrosive level of aragonite saturation state (v ca. 1.1�1.2) were found. furthermore, our results, despite the uncertainties and assumptions involved, showed that during our survey the ross sea acted as a sink for atmospheric co2 with a large variability, depending on biological activity and wind speed. climate change feedbacks such as ocean warming, deep-water ventilation changes, and sea-ice melt potentially alter future ocean carbonate conditions found in this study both in the surface and the deep layers of the ross sea with some consequences on the role of the aabw in the export of inorganic carbon, particularly in the capture of the anthropogenic co2. therefore, further investigations in the ross sea are necessary to confirm the findings to date and to investigate the temporal evolution of the carbonate system properties. acknowledgements this study was carried out as part of the pnra clima and terranova bay research experiment (t-rex) projects and was funded by the italian national agency for new technologies, energy and sustainable economic development through a joint research programme. the help of the crew on the rv italica is kindly acknowledged. the authors are grateful to prof. g.l. gragnani (university of genoa) for the calculation performed by gnuplot software. seawifs analyses and visualizations used in this paper were produced with the giovanni online data system, developed and maintained by the national aeronautics and space administration’s goddard earth sciences data and information services center. we thank novilinguists multimedia for the english editing. the comments and the suggestions of the referees were greatly appreciated and improved this paper. references ackley s.f., buck k.r. & taguchi s. 1979. standing crop of algae in the sea ice of weddell sea region. deep-sea research part i 26, 269�281. arrigo k.r., robinson d.h., worthen d.l., dumbar r.b., di tullio g.r., van woerth m. & lizotte m.p. 1999. phytoplankton community structure and the drawdown of nutrient and co2 in the southern ocean. science 283, 365�367. arrigo k.r. & van dijken g.l. 2004. annual changes in seaice, chlorophyll-a, and primary production in the ross sea, antarctica. deep-sea research part ii 51, 117�138. arrigo k.r. & van dijken g.l. 2007. interannual variation in sea�air co2 flux in the ross sea, antarctica: a model distribution of total alkalinity and ph in the ross sea p. rivaro et al. 12 (page number not for citation purpose) citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 analysis. journal of geophysical research*oceans 112, 03020, doi: 10.1029/2006jc003492. barbini r., fantoni r., palucci a., colao f., sandrini s., ceradini s., tositti l., tubertini o. & ferrari g.m. 2003. simultaneous measurements of remote lidar chlorophyll and surface co2 distributions in the ross sea. international journal of remote sensing 24, 3807�3819. bates n.r., hansell d.a. & carlson c.a. 1998. distribution of co2 species, estimates of net community production, and sea�air co2 exchange in the ross sea polynya. journal of geophysical research*oceans 103, 2883�2896. bednaršek n., tarling g.a., bakker d.c.e., fielding s., jones e.m., venables h.j., ward p., kuzirian a., lézé b., feely r.a. & murphy e.j. 2012. extensive dissolution of live pteropods in the southern ocean. nature geoscience 12, 881�885. bellerby r.g.j., hoppema m., fahrbach e., de baar h.j.w. & stoll m.h.c. 2004. interannual controls on weddell sea surface water fco2 during the autumn�winter transition phase. deep-sea research part i 51, 793�808. bromwich d.a., parish t.r. & zorman c.a. 1990. the confluence zone of the intense katabatic winds at terra nova bay, antarctica, as derived from airborne sastrugi surveys and mesoscale numerical modelling. journal of geophysical research*atmospheres 95, 5495�5509. budillon g., castagno p., aliani s. & spezie g. 2011. thermohaline variability and antarctic bottom water formation at the ross sea shelf break. deep-sea research part i 58, 1002�1018. budillon g., pacciaroni m., cozzi s., rivaro p., catalano g., ianni c. & cantoni c. 2003. an optimum multiparameter mixing analysis of the shelf waters in the ross sea. antarctic science 15, 105�118. budillon g., salusti e. & tucci s. 2006. the evolution of density currents and nepheloid bottom layers in the ross sea (antarctica). journal of marine research 64, 517�540. budillon g. & spezie g. 2000. thermohaline structure and variability in the terra nova bay polynya (ross sea) between 1995�98. antarctic science 12, 501�516. caldeira k. & duffy p.b. 2000. the role of the southern ocean in uptake and storage of anthropogenic carbon dioxide. science 287, 620�622. chierici m. & fransson a. 2009. caco3 saturation in the surface water of the arctic ocean: undersaturation in freshwater influenced shelves. biogeosciences 6, 2421�2432. dickson a.g. 1990. standard potential of the reaction: agcl(s)�1/2 h2(g) �ag(s)�hcl(aq), and the standard acidity constant of the ion hso�4 in synthetic seawater from 273.15 to 318.15 k. journal of chemical thermodynamics 22, 113�127. dinniman m.s., klinck j.m. & smith w.o. jr. 2003. crossshelf exchange in a model of the ross sea circulation and biogeochemistry. deep-sea research part ii 50, 3103�3120. doe (us department of energy) 1994. handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water. version 2.0. ornl/cdiac-74. a.g. dickson & c. goyet (eds.). accessed on the internet at http://cdiac.esd. ornl.gov/oceans on 03 october 2014. doe (us department of energy). 2007a. handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water. version 2.0. ornl/cdiac-74. a.g. dickson & c. goyet (eds.). accessed on the internet at http://cdiac. esd.ornl.gov/oceans on 29 august 2014. doe (us department of energy) 2007b. handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water. version 3.0. a.g. dickson & c. goyet (eds.). accessed on the internet at http://cdiac.esd.ornl.gov/ oceans on 29 august 2014. feng y., hare c.e., rose j.m., handy s.m., di tullio g.r., lee p.a., smith w.o. jr., peloquin j., tozzi s., sun j., zhang y., dunbar r.b., long m.c., sohst b., lohan m. & hutchins d.a. 2010. interactive effects of iron, irradiance and co2 on ross sea phytoplankton. deep-sea research part i 57, 368�383. fofonoff p. & millard r.c. 1983. algorithms for computation of fundamental properties of seawater. unesco technical papers in marine science 44. paris: united nations educational, scientific and cultural organization. fusco g., budillon g. & spezie g. 2009. surface heat fluxes and thermohaline variability in the ross sea and in terra nova bay polynya. continental shelf research 29, 1887�1895. garrison d.l., gibson a., kunze h., gowing m.m., vickers c.l., mathot s. & bayre r.c. 2003. the ross sea polynya project: diatomand phaeocysis-dominated phytoplankton assemblages in the ross sea, antarctica, 1994�1996. in g. di tullio & r.b. dunbar (eds.): biogeochemistry of the ross sea. pp. 53�76. washington dc: american geophysical union. gordon a.l., orsi a.h., muench r., huber b.a., zambianchi e. & visbeck m. 2009. western ross sea continental slope gravity currents. deep-sea research part ii 56, 796�817. gordon a.l., padman l. & bergamasco a. 2009. southern ocean shelf slope exchange. deep-sea research part ii 56, 775�777. gordon l.i., codispoti l.a., jennings j.c. jr., millero f.j., morrison j.m. & sweeney c. 2000. seasonal evolution of hydrographic properties in the ross sea, antarctica, 1996�1997. deep-sea research part ii 47, 3095�3117. honjo s. 2004. particle export and the biological pump in the southern ocean. antarctic science 16, 501�516. hopkins t.l. 1987. midwater food web in mcmurdo sound, ross sea, antarctica. marine biology 89, 197�212. jacobs s.s., fairbanks r.c. & horibe y. 1985. origin and evolution of water masses near the antarctic continental margin: evidence from h2 18 o/h2 16 o ratios in seawater. antarctic research series 43, 59�85. jacobs s.s. & giulivi c.f. 1999. thermohaline data and ocean circulation on the ross sea continental shelf. in g. spezie & g.m.r. manzella (eds.): oceanography of the ross sea, antarctica. pp. 3�16. berlin: springer. jackett r. & mcdougall t.j. 1997. a neutral density variable for the world’s oceans. journal of physical oceanography 27, 237�263. p. rivaro et al. distribution of total alkalinity and ph in the ross sea citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 13 (page number not for citation purpose) http://cdiac.esd.ornl.gov/oceans http://cdiac.esd.ornl.gov/oceans http://cdiac.esd.ornl.gov/oceans http://cdiac.esd.ornl.gov/oceans http://cdiac.esd.ornl.gov/oceans http://cdiac.esd.ornl.gov/oceans http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 laika h.e., goyet c., vouve f., poisson a. & touratier f. 2009. interannual properties of the co2 system in the southern ocean south of australia. antarctic science 21, 663�680. lee k., tong l.t., millero f.j., sabine c.l., dickson a.g., goyet c., park g.h., wanninkhof r., feely r.a. & key r.m. 2006. global relationships of total alkalinity with salinity and temperature in surface waters of the world’s oceans. geophysical research letters 33, l19605, doi: 10.1029/2006 gl027207. mangoni o., modigh m., conversano f., carrada g.c. & saggiomo v. 2004. effects of summer ice coverage on phytoplankton assemblages in the ross sea, antarctica. deep-sea research part i 5, 1601�1617. manno c., sandrini s., tositti l. & accornero a. 2007. first stages of degradation of limacina helicina shells observed above the aragonite chemical lysocline in terra nova bay (antarctica). journal of marine system 68, 91�102. massolo s., messa r., rivaro p. & leardi r. 2009. annual and spatial variations of chemical and physical properties in the ross sea surface waters (antarctica). continental shelf research 29, 2333�2344. mcneil b.i. & matear r. 2008. southern ocean acidification: a tipping point at 450 ppm atmospheric co2. proceedings of the national academy of sciences of the united states of america 105, 18860�18864. mcneil b.i., tagliabue a. & sweeney c. 2010. a multi-decadal delay in the onset of corrosive ‘acidified’ waters in the ross sea of antarctica due to strong sea�air co2 disequilibrium. geophysical research letters 37, l19607, doi: 10.1029/2010 gl044597. metzl n., tilbrook b. & poisson a. 1999. the annual fco2 cycle and the air�sea co2 flux in the sub-antarctic ocean. tellus series b 51, 849�861. millero f. 2007. the marine inorganic carbon cycle. chemical reviews 107, 308�341. mitchell b.g. & holm-hansen o. 1991. observation and modelling of the antarctic phytoplankton crop in relation to mixing depth. deep-sea research part i 38, 981�1007. mucci a. 1983. the solubility of calcite and aragonite in seawater at various salinities, temperatures, and one atmosphere total pressure. american journal of science 283, 780�799. orsi a.h., johnson g.c. & bullister j.l. 1999. circulation, mixing, and production of antarctic bottom water. progress in oceanography 43, 55�109. orsi a.h. & wiederwohl c.l. 2009. a recount of ross sea waters. deep-sea research part ii 56, 778�795. parish t.r. & bromwich d.a. 1989. instrumented aircraft observations of the katabatic wind regime near terra nova bay. monthly weather review 117, 1570�1585. pierrot d., lewis e. & wallace d.w.r. 2006. ms excel program developed for co2 system calculations, ornl/cdiac-105. oak ridge, tn: carbon dioxide information analysis center, oak ridge national laboratory, us department of energy. poisson a., metzl n., brunet c., schauer b., brès b., ruiz-pino d. & louanchi f. 1993. variability of sources and sinks of co2 in the western indian and southern oceans during the year 1991. journal of geophysical research*oceans 98, 22759�22778. reddy t.e., arrigo k.r. & holland d.m. 2007. the role of thermal and mechanical processes in the formation of the ross sea summer polynya. journal of geophysical research* oceans 112, c07027, doi: 10.1029/2006jc003874. redfield a.c., ketchum b.h. & richards f.a. 1963. the influence of organisms on the composition of sea water. in m.n. hill (ed.): the sea. vol. 2. pp. 26�77. new york: interscience. rivaro p., bergamasco a., budillon g., frache r., hohmann r., massolo s. & spezie g. 2004. chlorofluorocarbon distribution in the ross sea water masses. chemistry and ecology 20, supplement 1, s29�s41. rivaro p., ianni c., massolo s., abelmoschi m.l., de vittor c. & frache r. 2011. distribution of dissolved labile and particulate iron and copper in terra nova bay polynya (ross sea, antarctica) surface waters in relation to nutrients and phytoplankton growth. continental shelf research 31, 879�889. rivaro p., massolo s., bergamasco a., castagno p. & budillon g. 2010. chemical evidence of the changes of the antarctic bottom water ventilation in the western ross sea between 1997 and 2003. deep-sea research part i 57, 639�652. rivaro p., messa r., massolo s. & frache r. 2010. distributions of carbonate properties along the water column in the mediterranean sea: spatial and temporal variations. marine chemistry 121, 236�245. roy r.n., roy l.n., vogel k.m., moore c.p., pearson t., good e.c., millero f.j. & campbell d.m. 1993. the dissociation constants of carbonic acid in seawater at salinities 5 to 45 and temperatures 0 to 458c. marine chemistry 44, 249�267. rubino a., budillon g., pierini s. & spezie g. 2003. a model for the spreading and sinking of the deep ice shelf water in the ross sea. antarctic science 15, 25�30. sabine c.l., feely r.a., gruber n., key r.m., lee k., bullister j.l., wanninkhof r., wong c.s., wallace d.w.r., tilbrook b., millero f.j., peng t., kozyr a., ono t. & rios a.f. 2004. the oceanic sink for anthropogenic co2. science 305, 367�371. sandrini s., aı̈t-ameur n., rivaro p., massolo s., touratier f., tositti l. & goyet c. 2007. anthropogenic carbon distribution in the ross sea (antarctica). antarctic science 19, 395�407. smethie w.m. jr. & jacobs s.s. 2005. circulation and melting under the ross ice shelf: estimates from evolving cfc, salinity and temperature fields in the ross sea. deep-sea research part i 52, 959�978. smith w.o. jr., dinniman m.s., klinck j.m. & hofmann e. 2003. biogeochemical climatologies in the ross sea, antarctica, seasonal patterns of nutrients and biomass. deep-sea research part ii 50, 3083�3101. smith w.o. jr. & nelson d.m. 1985. phytoplankton bloom produced by a receding ice edge in the ross sea: spatial coherence with the density field. science 227, 163�166. smith w.o. jr., nelson d.m., ditullio g.r. & leventer a.r. 1996. temporal and spatial patterns in the ross sea: phytoplankton biomass, elemental composition, productivity distribution of total alkalinity and ph in the ross sea p. rivaro et al. 14 (page number not for citation purpose) citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 and growth rates. journal of geophysical research*oceans 101, 18455�18466. sweeney c. 2003. the annual cycle of surface water co2 and o2 in the ross sea: a model for gas exchange on the continental shelves of antarctica. in g. di tullio & r.b. dunbar (eds.): biogeochemistry of the ross sea. pp. 295�312. washington, dc: american geophysical union. sweeney c., hansell d.a., carlson c.a., codispoti l.a., gordon l.i., marra j., millero f.j., smith w.o. & takahashi t. 2000. biogeochemical regimes, net community production and carbon export in the ross sea, antarctica. deep-sea research part ii 47, 3369�3394. tagliabue a. & arrigo k.r. 2006. processes governing the supply of iron to phytoplankton in stratified seas. journal of geophysical research*oceans 111, c06019, doi: 10.1029/ 2005jc003363. takahashi t., sutherland s.c., sweeney c., poisson a., metzl n., tilbrook b., bates n., wanninkhof r., feely r.a., sabine c., olafsson j. & nojiri y. 2002. global sea�air co2 flux based on climatological surface ocean pco2, and seasonal biological and temperature effects. deep-sea research part ii 49, 1601�1622. tortell p.d., guéguen c., long m.c., payne c.d., leeand p. & di tullio g.r. 2011. spatial variability and temporal dynamics of surface water pco2, do2/ar and dimethylsulfide in the ross sea, antarctica. deep-sea research part i 58, 241�259. tremblay j.e. & smith w.o. jr. 2007. primary production and nutrient dynamics in polynyas. in w.o. smith & d.g. barber (eds.): polynyas: windows to the world. pp. 239�269. amsterdam: elsevier. unesco (united nations educational, scientific and cultural organization) 1988. the acquisition, calibration, and analysis of ctd data. a report of scor working group 51. unesco technical papers in marine science 54. paris: united nations educational, scientific and cultural organization. wanninkhof r. 1992. relationship between wind speed and gas exchange over the ocean. journal of geophysical research*oceans 97, 7373�7382. wanninkhof r. & mcgillis w.r. 1999. a cubic relationship between sea�air co2 exchange and wind speed. geophysical research letters 26, 1889�1892. weiss r.f. 1974. carbon dioxide in water and seawater: the solubility of a non-ideal gas. marine chemistry 2, 203�215. weiss r.f. & price b.a. 1980. nitrous oxide solubility in water and seawater. marine chemistry 8, 347�359. whitworth t., iii, orsi a.h., kim s.j. & nowlin w.d. jr. 1998. water masses and mixing near the antarctic slope front. in s.s. jacobs & r.f. weiss (eds.): ocean, ice, and atmosphere: interactions at the antarctic continental margin. pp. 1�27. washington, dc: american geophysical union. p. rivaro et al. distribution of total alkalinity and ph in the ross sea citation: polar research 2014, 33, 20403, http://dx.doi.org/10.3402/polar.v33.20403 15 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20403 http://dx.doi.org/10.3402/polar.v33.20403 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice book review book review book review of thinking like an iceberg, by olivier remaud (2022). stephen muecke, trans. medford, ma: polity. 180 pp. isbn 978-1-509-55148-4.   citation: polar research 2023, 42, 9249, http://dx.doi.org/10.33265/polar.v42.9249 copyright: polar research 2023. © 2023 i. gapp. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 19 january 2023 correspondence to: isabelle gapp, department of art history, university of toronto, sidney smith hall, 100 george st., toronto, on m5s 3g3, canada. e-mail: icbgapp@gmail.com   what does it involve to think like an iceberg? such is the question posed by philosopher olivier remaud in thinking like an iceberg. translated from the original french (penser comme un iceberg) into english by stephen muecke, the book explores the multifaceted and porous histories of describing and thinking about and alongside ice. taken as a whole, the book brings together glaciology, environmental history, anthropological studies and accounts, and historic and contemporary aesthetic responses to ice. it takes up the call by mark carey et al. to generate alternative approaches to and representations of ice through “storytelling, narrative, literature, and the visual arts” (carey et al. 2016: 15). through remaud’s writing, ice manifests a human-like consciousness, with icebergs reduced to a human-like scale for our better understanding. by synthesizing historical and contemporary research into the social, cultural and environmental histories of, and relationships with, ice, remaud encourages the reader to query how icebergs might be thought of as alive and as active agents in their own futurity. remaud begins (and ends) with a fictional retelling of captain james cook’s 18th-century voyage in search of terra australis from the perspective of an iceberg: “call me the ‘impassable’. i am the one who stopped cook on his second voyage around the world” (p. 2). playing on the custom of naming ships, remaud introduces the personified narrative of the ice that is the leitmotif of the book. steeped in metaphor, the shifting perspective of the narrator is at times disorientating, as the reader tries to untangle the voices of remaud, other scholars and the implied consciousness of the ice across human histories and geographies. these geographies are often firmly rooted in the arctic and antarctic, with few exceptions. at the outset of chapter one, remaud introduces frederic edwin church’s painting, the icebergs (1861, dallas museum of art), alongside louis legrand noble’s written account of the voyage that inspired the painting (noble 1861), as indicative of a western cultural imagination. remaud writes that the two men were “iceberg hunters” (p. 4), tasked with recreating the sublime experience of the ice on paper and in painting. following this, the author’s own experiences during a trip to iceland are briefly situated within the human fascination for ice. exploring the aesthetics of the sublime through noble’s detailed depiction, remaud leans into the role of metaphor used to describe ice within historic exploratory accounts. he writes, “the metaphorical gaze, transposing one environment into another, is no less a characteristic of the romantic spirit. western travellers are wordsmiths. they make sentences” (p. 16). the heavy use of metaphor and analogy is both a strength and weakness of remaud’s narrative. at times evocative of the capacity of human and animal life to inform an understanding of icebergs, these metaphors largely turn the history and story of ice into a tangled web of words. this aesthetic fascination with ice continues into the second chapter, wherein remaud explores the creation of icebergs; in other words, where do icebergs come from? beyond using glaciology to explain the formation of glaciers, remaud writes how “a drop of liquid falls from the sky in the shape of a snowflake” (p. 29), these building up in layers over millennia to form an icesheet. through this evolutionary process, glaciers, like icebergs, are regarded as being alive. “[i]f they move, are they alive?” asks remaud (p. 33). glaciers and icebergs are described in relation to human and animal behaviour. the glacier, the mother, becomes the iceberg, her child. the use of “mother” by glaciologists in relation to certain glaciers is turned by remaud into an elaborate familial bond between glacier and iceberg. remaud extends this metaphor to the behaviour of whales, noting the parallels between icebergs and whale calves as described by kalaaleq whalers and hunters and retold by western whalers in the 19th century. remaud claims that through the words given to glaciers and icebergs, humans have given them life. consideration of ice in non-arctic and non-european environments, such as in iran, the andes and the himalayas, and engagement with the work of karine gagné, ravi baghel and peter g. knight among others, would have further strengthened remaud’s study of ice as a global agent. in the third chapter, remaud explores life on the ice and takes us below the water’s surface into invisible icy spaces. remaud proposes that, unlike the sublime, which was preoccupied with the iceberg visible above the water’s surface, “the realm of the iceberg lies below the waterline. its soul resides in the underwater world” (p. 86). drawing upon the work of barry lopez, remaud describes ice as simultaneously disorientating and teeming with life. he reanimates lopez’s discussion in arctic dreams (1986) of the submerged body of the iceberg as a distinct ecotone. here, the surprising appearance of qr codes printed onto the pages of thinking like an iceberg allows the soundscape of ice to be experienced through film and audio recordings of the movement of ice below the water’s surface. meanwhile, movement atop the ice is transformed by remaud into an ethnography of inuit wayfinding with reference to the work of anthropologists edmund carpenter and tim ingold. the following chapter largely focuses on the presence of ice as a part of inuit society. here, environmental memory is juxtaposed with inuit birth memories, where the baby is like the iceberg that calves from the mother (glacier). and yet, first-hand inuit voices and memories and the work of inuit scholars are notably absent. only zacharias kunuk’s film, atanarjuat: the fast runner (2001), intersects remaud’s retelling of inuit relationships to ice. the work of julie cruikshank is used to highlight these social relationships. meanwhile, inuit perspectives are filtered through the work of primarily white anthropologists, geographers and novelists, including bernard saladin d’anglure, shari fox and bérangère cournut. such a focus required engagement with, to name only a handful of examples, the writings and artistry of sheila watt-cloutier, jen rose smith, joan naviyuk kane, tanya tagaq and laakkuluk williamson bathory or independent collaboration and conversation between remaud and inuit communities, those to whom these stories belong. just as western language has given life to ice, inuit words that describe the different types of ice and its behaviour “confirm that language constantly registers the modified states of ice” (p. 102). although human action and interaction are seen by remaud as the main culprits behind climate change, he also notes the effect of ice on human behaviour. bringing together numerous western scholarly perspectives on indigenous relationships to ice, remaud summarizes that spiritual rituals are themselves dying as icebergs are melting. icebergs “are upset: no one speaks to them any more,” he concludes (p. 117). remaud explores the idea that glaciers and icebergs are aware of their own mortality, and that they are “undoubtedly an ‘endangered species’ today” (p. 127). in chapter 5, our focus is diverted to glaciers that have been classed as heritage sites, going beyond the idea of ice as archive. remaud queries, how do you preserve something that is in a perpetual state of melting? memorializations of ice, such as with the “death” of the okjökull glacier in iceland, are included as examples of how ice “incorporates the history of the earth as well as that of humanity” (p. 138), with humans conversely facing their own mortality. as snow no longer has time to build up and form glacial masses, glaciers themselves become more and more like icebergs, fleeting and melting. “if no ice covers the earth, the world itself becomes lonely,” suggests remaud (p. 152). problematizing the use of the term “wilderness” to describe ice and the cryosphere because it implies that glaciers and icebergs exist in solitude, remaud proposes that “to abandon the representation of the solitary iceberg is to begin to repopulate the ice worlds” (p. 134). by giving agency to ice, the cryosphere becomes a site that has always been teeming with life as well as itself being alive. at the end of his book, remaud reformulates his leading question by asking “who has ever thought like an iceberg?” (p. 155). returning to the earlier analogy between ice and birth, remaud tells a fictitious story centred around a young inuit boy: “he has become an iceberg again” (p. 155). inuit perspectives and agency are used by remaud as tools to reaffirm the agency of ice. returning to the role of the narrator, the “we” of the story, remaud takes us back to the boat that carried church and noble towards the icebergs, before then returning to the “wild life” of icebergs (p. 157). in this succinct conclusion, remaud proposes that icebergs are teachers. they “are discreet colossi, antidotes to narcissism,” through whom humans might learn to better themselves and improve their understanding of global climate change: “in them lies the preservation of the world. it is time to think like an iceberg” (p. 159). thinking like an iceberg tells a detailed and imaginative story of ice that sees ice as aware of its own existence and fate and its role within human society and history. through the elaborate use of metaphor and the narrative retelling of existing scholarship, remaud’s philosophical contribution to the field of ice humanities, recently proposed by dodds & sörlin (2022), is a challenging read. as glaciers continue to melt at alarming rates and ever-larger icebergs calve into the ocean, remaud has created a book that prompts us to contemplate in a new way what it means to lose this shifting, cracking, bubbling and increasingly temporary structure and surface. references carey m., jackson m., antonello a. & rushing j. 2016. glaciers, gender, and science: a feminist glaciology framework for global environmental change research. progress in human geography 40, 770–793, doi: 10.1177/030913251562336. dodds k. & sörlin, s. (eds.) 2022. ice humanities: living, thinking and working in a melting world. manchester: manchester university press. kunuk z. (director) 2001. atanarjuat: the fast runner. isuma igloolik productions. lopez b. 1986. arctic dreams: imagination and desire in a northern landscape. new york: charles scribner’s sons. noble l.l. 1861. after icebergs with a painter: a summer voyage to labrador and around newfoundland. new york: d. appleton and company. no job name the effect of sea-ice loss on beluga whales (delphinapterus leucas) in west greenlandpor_142 198..208 m.p. heide-jørgensen,1 k.l. laidre,1,3 d. borchers,2 t.a. marques,2 h. stern3 & m. simon1 1 greenland institute of natural resources, box 570, dk-3900 nuuk, greenland 2 research unit for wildlife population assessment, centre for research into ecological and environmental modelling, university of st. andrews, st. andrews, fife ky16 9lz, uk 3 polar science center, applied physics laboratory, university of washington, box 355640, seattle, wa 98105, usa abstract an aerial survey was conducted to estimate the abundance of belugas (delphinapterus leucas) on their wintering ground in west greenland in march–april 2006 and 2008. the survey was conducted as a double platform aerial line transect survey, and sampled approximately 17% of the total survey area of ca. 125 000 km2. the abundance of belugas was 10 595 (95% confidence interval 4904–24 650). the largest abundance was found at the northern part of store hellefiske bank, at the eastern edge of the baffin bay pack ice, a pattern similar to that found in eight systematic surveys conducted since 1981. a clear relationship between decreasing sea-ice cover and increasing offshore distance of beluga sightings was established from all previous surveys, suggesting that belugas expand their distribution westward as new areas on the banks of west greenland open up earlier in spring with reduced sea-ice coverage or early annual ice recession. this is in contrast to the relatively confined distribution of belugas near the coast in limited open areas in the early 1980s, when sea-ice cover was greater. however, the effects of the changes in coastal availability of belugas can also be observed with the correlation between catches from the local inuit hunt and sea-ice cover, where the catches increased significantly with increasing sea-ice coverage during the period 1954–2006. these results, based on nearly 30 years of dedicated survey effort, are among the first available evidence showing a shift in distribution of an arctic cetacean in response to changes in sea-ice coverage. keywords beluga; climate change; line transect; sea ice; west greenland. correspondance mads peter heide-jørgensen, greenland institute of natural resources, box 570, dk-3900 nuuk, greenland. e-mail: mhj@ghsdk.dk doi:10.1111/j.1751-8369.2009.00142.x the beluga or white whale (delphinapterus leucas) is a medium-sized odontocete whale that lives year-round in arctic waters. a large population that summers in the eastern canadian high arctic migrates eastward in fall, and overwinters either in the north water polynya or in the loose pack ice along west greenland (heidejørgensen et al. 2003). belugas arrive in the northern part of west greenland in early october and move south along the coast, arriving in disko bay in december. they remain scattered on the shallow banks along the west greenland coast during winter, where they feed and benefit from the rich marine production in the area. the northward spring migration begins sometime in april or may. belugas leave the areas south of disko island and move north in the coastal open water along uummannaq and upernavik. they are believed to cross baffin bay somewhere at the latitude of upernavik (about 73°n), and they arrive at the ice edge in lancaster sound in canada in may and june. beluga whales are one of the three cetacean species that occupy arctic waters essentially year-round. however, little is known about the effects of climate change on this species, as there are few data sets in which a single population has been systematically monitored over a sufficiently long enough time period to detect changes in abundance, distribution or behaviour, and correlate changes with changes in the environment. the beluga is believed to be a relatively flexible species in that it preys upon a large number of different species and can occupy a wide variety of different habitat types, ranging polar research 29 2010 198–208 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd198 mailto:mhj@ghsdk.dk from high arctic ice-covered waters to sub-arctic estuaries. because this whale is a relative generalist and is not assumed to be highly vulnerable to climate change (laidre et al. 2008), it has been suggested that belugas may be able to occupy new areas and exploit new ecosystems as sea-ice loss opens new regions within their range. the winter occurrence of belugas in west greenland has been used to index the population trends in the stock hunted from villages along the coast. the area in west greenland used by belugas during winter is typically covered with pack ice from january to may. seasonal sea-ice cover in baffin bay has essentially confined this wintering population to a relatively defined region, facilitating a surveying effort that covered about 50 000 km2 between 1981 and 1999. the abundance of belugas was surveyed eight times between 1981 and 1999 to provide an index of the population size on the banks off west greenland (heide-jørgensen et al. 1993; heidejørgensen & reeves 1996; heide-jørgensen & acquarone 2002). in order to address important questions about the effect of habitat changes on cetacean populations it is necessary to have long time series. the aerial surveys conducted off west greenland since 1981 constitute the only time series of winter habitat use by arctic cetaceans that extends sufficiently far back in time to include a period when sea ice was not declining in the arctic. detailed information on catches of belugas in west greenland covering the period back to 1954 is available. it is well known that the effects and speed of climate change are amplified in the arctic, and that sea ice, because of the ice–albedo feedback, is an important factor in the arctic amplification of global warming (e.g., serreze & francis 2006). the west greenland area is a particularly sensitive climate area in the arctic because of the competing effects of the advection of warm, saline atlantic water to the west greenland banks, and the simultaneous outflow through davis strait of cold, low-saline water of polar origin. during the period 1952–2001 the extent of sea ice in west greenland increased slightly by 2.8% per decade (stern & heide-jørgensen 2003), but after 2001 a dramatic decline in sea ice has been observed along west greenland (comiso 2006; greenland institute of natural resources unpubl. data). it is therefore important to not only obtain an updated estimate of beluga abundance, but also to examine the impacts of changes in sea ice on measures of beluga abundance and distribution. this study reports on the results from aerial surveys of the beluga wintering grounds in west greenland conducted in march and april 2006, and in april 2008, together with an examination of changes in beluga distribution with respect to changes in sea-ice cover during the past 30 years. methods field methods a visual aerial line-transect survey was conducted in west greenland between 21 march and 19 april 2006. the survey had two independent observation platforms on each side of the survey plane (dehavilland twin otter with four bubble windows), with a target altitude of 213 m a.s.l. and speed of 168 km h–1. data on sightings (species and numbers), inclinometer readings of declination angles to sightings and sighting conditions (sea state and visibility) were continuously recorded on four tape recorders, together with time-stamp signals on position from a garmin 100 gps device (garmin international, olathe, ks, usa). following the design and stratification used in previous surveys (see heide-jørgensen & reeves 1996) the survey covered 14 strata with east–west transects systematically placed from south to north, beginning at maniitsoq (65°30′n), and reaching northern upernavik (74°n) in west greenland. additional transects sampled disko bay, vaigat and uummannaq (fig. 1). the survey was abandoned if sea states increased to more than 3 or if horizontal visibility was reduced to less than 1 km. in april 2008 a supplementary survey systematically covered the area east of 56°w, and between 67 and 70°n. the survey used the same aircraft, four observers and same survey procedures as in the 2006 survey, but is not used for abundance estimation. sightings of belugas were recorded on an sdvr-ms combined video, still image, gps device and four audio channel recording system (red hen systems, fort collins, co, usa). information on sea-ice conditions data on sea-ice conditions in baffin bay were derived from monthly gridded sea-ice concentrations, measured by passive microwave sensors from the scanning multichannel microwave radiometer (smmr, 1978–1987) and the special sensor microwave imager (ssmi, on various satellites since 1987). this data set was augmented by the ssmi from the f13 satellite (from may 1995 to the present). both data sets are derived using the bootstrap algorithm for sea-ice concentration (comiso 1995), and are available from the national snow and ice data center. sea-ice data from march 2008 were obtained from the ssmi f15 near real time daily products (nasa team algorithm). each sea-ice concentration grid for the northern hemisphere is 304 ¥ 448 pixels, and is mapped to a polar stereographic projection (true at 70°n) with a nominal pixel size of 25 ¥ 25 km. the “medium area” (boundaries: 65–70°n, and from the west coast of greenland to 58°w) along west greenland defined in stern & heidethe effect of sea-ice loss on beluga whalesm.p. heide-jørgensen et al. polar research 29 2010 198–208 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 199 jørgensen (2003) was used for the estimation of the annual sea-ice extension in the beluga habitat in west greenland. the sea-ice concentration in march, typically the month with the largest concentration, was used to compute an area-weighted average over all pixels to get the mean winter sea-ice concentration. thus, the monthly estimates of ice concentration involved spatial and temporal averaging. sighting data declination angles (q) were converted to perpendicular distances (r) using the formula: r 2 2 2213 180 213= [ ] −( )sin * .θ π a total of 119 beluga sightings were recorded. five of those did not have a recorded declination angle, and two lacked information on cluster size. these were excluded from the analysis to avoid bias from sightings with missing information, resulting in 112 sightings to be used in further analysis. beaufort sea state 0 was assigned to 13 sightings without an associated beaufort value, as the general sea-state condition was known during the trackline upon which they were obtained. detection function model selection detection probability was estimated using the “point independence” method with independent observer configuration (laake & borchers 2004; borchers et al. 2006), implemented in distance 5.0 (thomas et al. 2006). this method involved estimating a multiple covariate distance sampling model (mcds model) for combined platform detections assuming certain detection at distance zero, and a mark–recapture distance sampling model (mrds model) for each of the independent observers using a logistic detection function model. the intercept of the mrds model was used to estimate detection probability at fig. 1 transect lines and distribution of sightings in the survey of belugas in west greenland, march–april 2006. sea ice is mapped from a modis image from 18 april 2006. the effect of sea-ice loss on beluga whales m.p. heide-jørgensen et al. polar research 29 2010 198–208 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd200 distance zero, whereas the mcds model was used to estimate detection function shape (see laake & borchers 2004 and borchers et al. 2006 for further details). models were chosen on the basis of akaike’s information criterion (aic). forward selection was used to choose between models based on aic values. first, half-normal and hazard-rate key functions were tested with no covariates. a regression of log of pod size on log of detection function was used to estimate an unbiased mean pod size for each stratum (ê[s]). the estimates for pod abundance and density by stratum were multiplied by the mean pod size by stratum to obtain estimates of individual abundance and density by stratum. total pod abundance and density estimates were also multiplied by the total mean pod size to obtain total individual abundance and density estimates. pod density and abundance were estimated as follows, corrected for availability bias following laake et al. (1997) and pollock et al (2006): ˆ ˆ ˆ n p a pod ii n = ( )= ∑ 1 01 and ˆ ˆ ,d n a pod = where a is the total area, n is the number of detections, p̂i is the estimated probability of detecting pod i and â(0) is the estimated proportion of time animals are available for detection. time at surface was calculated as the mean of the correction factors from two previous surveys, to correct for availability bias (heide-jørgensen & acquarone 2002; innes et al. 2002). to include the population variance on the surfacing time, an estimate of the coefficient of variation was set to 0.09, or slightly less than the coefficient of variation (cv, standard error in proportion to the mean) reported for a small sample (n = 4) of narwhals (monodon monoceros) (cv = 0.13). this was equal to an instantaneous correction factor â(0) = 0.43 (cv = 0.09). assuming independence between components, the cv of the abundance and density estimates were estimated as follows: c v n c v c v c vn e s apod ˆ .ˆ ˆ ˆ( ) = + +( ) ( )2 2 02 the 95 and 90% confidence intervals (cis) were calculated following the derivation of burnham et al. (1987, in buckland et al. 2001: 77). interannual comparison of beluga locations in the region between 67 and 70°n beluga abundance has been surveyed systematically with the same east–west transect lines in 1981, 1982, 1990, 1991, 1993, 1994, 1998 and 1999, allowing for comparison of the distribution of whales in this area (heide-jørgensen et al. 1993; heide-jørgensen & reeves 1996; heide-jørgensen & acquarone 2002). surveys after 1990 relied on gps, the surveys in 1981 and 1982 used the gns 500 global navigational system device (garmin international), and the survey in 1990 used a 3000 omega navigational system device (litton industries, acquired in 2001 by northrup grumman, los angeles, ca, usa). surveys in 1981 and 1982 of baffin bay and davis strait found no belugas west of 56°w in late march (heide-jørgensen et al. 1993), so later surveys were restricted to 56°w. the comparison between years with surveys was constrained to a subset of longitudes that were surveyed in all years, which extended to 56°w, and were located between 67 and 70°n. the mean longitude of beluga sightings (in decimal degrees) in each survey year within the restricted area was calculated. in each year the mean longitude was examined with respect to sea-ice concentration in the “medium area” (see above), which has been shown to be correlated with the sea-ice conditions in the surveyed area (see heide-jørgensen & laidre 2004). results distribution of belugas the surveys were conducted between 21 march and 19 april 2006, and between 3 and 12 april 2008, beginning in the southern strata (figs. 1, 2). because of inclement weather conditions most work was completed between 7 and 24 april 2006 (table 1). in 2006 belugas were primarily found in coastal areas along west greenland and over shallow water (<200 m deep). no belugas were found south of 67°n or north of 73°n, and none were detected in disko bay and in uummannaq. belugas were seen in the highest densities at the northern edge of store hellefiske bank, just west of disko island, in the northern opening of vaigat and off upernavik. at the northern edge of store hellefiske bank, belugas were observed at the western end of the transect indicating that whales may have been present even further west in this area. few whales were seen in open water, and they seemed to be closely associated with the eastern margin of the pack ice that covers most of baffin bay and davis strait (fig. 1). in 2008 the belugas were more restricted in their offshore distribution because of the wider distribution of pack ice, and most sightings were made in open water close to the coast (fig. 2). the effect of sea-ice loss on beluga whalesm.p. heide-jørgensen et al. polar research 29 2010 198–208 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 201 abundance of belugas in 2006 almost half of the detections in 2006 were of single whales, with only about 13% of the pod sizes being larger than five whales. the overall estimate of mean pod size was 3.0 (cv = 0.11). the unbiased or expected estimates of mean pod sizes varied between one and four whales, with an overall mean across all strata of 2.9 whales per pod (cv = 0.20; table 1). a hazard-rate key function with beaufort sea state and cluster size as covariates was selected based on its lower aic value, and estimates of abundance and density were obtained from this model with a right truncation at 1000 m (fig. 3). the largest abundance of belugas was found in stratum 3 (5891, cv = 0.78), which covered the northern portion of store hellefiske bank. the second largest abundance was found in stratum 13 in upernavik (3256, cv = 0.44). the total abundance at the surface, and corrected for perception bias, summed across all strata was 5298 belugas (95% ci 2407–11 676). the total abundance corrected for both perception and availability bias was 11 773 belugas (cv = 0.43; table 1). the correction for availability bias assumes that the sighting process was instantaneous, which is generally not true as some whales are sighted ahead of the plane. to address this point we used a correction model developed for narwhals based on mclaren’s formula (mclaren 1961), in which the whales were visible for an average of 4 s from the airplane, with a dive cycle of 36 s at the surface and 167 s submerged below 2 m (richard et al. in press). this correction model shows that because of the non-instantaneous sighting process, the instantaneous availability correction has a positive bias of roughly 10%. adjusting for this factor results in a revised abundance estimate of 10 595 (95% ci 4904– 24 650) belugas in west greenland in march–april 2006. fig. 2 transect lines and distribution of sightings in the survey of belugas in west greenland, april 2008. sea ice is mapped from a modis image from 3 april 2008. the effect of sea-ice loss on beluga whales m.p. heide-jørgensen et al. polar research 29 2010 198–208 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd202 ta b le 1 s u m m ar y st at is ti cs o f su rv e y re su lt s. t h e to ta la b u n d an ce o f b e lu g as (n � ) is co rr e ct e d fo r an av ai la b ili ty b ia s o f 0 .4 3 (c v = 0 .0 9 ). s tr at u m a re a (k m 2 ) a s u rv e y d at e s tr an se ct s tr an se ct le n g th (k m ) l n u m b e r o f d e te ct io n s n en co u n te r ra te n /l d e n si ty o f p o d s d̂ a b u n d an ce o f w h al e s u n co rr e ct e d fo r av ai la b ili ty b ia s n d e n si ty o f w h al e s a b u n d an ce o f p o d s co rr e ct e d fo r av ai la b ili ty b ia s ex p e ct e d p o d si ze a b u n d an ce o f w h al e s n̂ 1 1 4 9 6 1 1 /4 2 9 1 .3 2 1 0 .0 1 1 0 0 .0 3 8 4 2 5 0 .0 3 8 4 5 8 1 .0 5 8 (1 .0 1 ) (1 .0 1 ) (1 .0 1 ) (1 .0 1 ) (0 ) (1 .0 1 ) 2 9 6 6 9 2 4 /3 , 1 1 /4 , 1 5 – 1 6 /4 1 2 1 3 2 8 .5 5 1 8 0 .0 1 3 5 0 .0 4 9 8 3 6 1 0 .0 8 6 7 4 8 1 1 .7 8 0 2 (0 .3 1 ) (0 .3 3 ) (0 .3 4 ) (0 .3 1 ) (0 .3 3 ) (0 .3 4 ) 3 8 6 1 3 2 3 – 2 4 /3 1 0 8 3 6 .9 7 4 4 0 .0 5 2 6 0 .1 7 8 8 2 6 5 1 0 .7 1 5 8 1 5 4 0 4 .0 5 8 9 1 (0 .5 8 ) (0 .7 7 ) (0 .7 8 ) (0 .5 8 ) (0 .9 3 ) (0 .7 8 ) 4 6 3 7 6 1 /4 , 6 – 7 /4 5 4 1 9 .3 8 0 0 0 0 0 0 0 0 5 8 0 4 1 7 /4 1 8 4 .1 9 0 0 0 0 0 0 0 0 6 5 9 3 5 1 /4 1 0 8 5 6 .5 3 0 0 0 0 0 0 0 0 7 8 2 0 5 2 1 /3 , 1 6 – 1 5 /4 1 0 1 0 7 5 .8 8 0 0 0 0 0 0 0 0 9 5 7 9 2 1 6 – 1 7 /4 1 2 4 9 0 .9 8 1 0 .0 0 2 0 0 .0 0 6 5 5 0 0 .0 2 0 0 4 0 3 .0 1 1 1 (1 .0 4 ) (1 .0 4 ) (1 .0 4 ) (1 .0 4 ) (0 ) (1 .0 4 ) 1 0 1 0 7 7 9 1 7 – 1 8 /4 6 5 2 2 .7 3 5 0 .0 0 9 6 0 .0 3 1 6 2 3 4 0 .0 5 0 5 3 4 0 1 .6 5 2 0 (0 .9 4 ) (0 .9 5 ) (0 .9 5 ) (0 .9 4 ) (0 .0 8 ) (0 .9 5 ) 1 2 3 6 1 2 1 7 – 1 9 /4 6 2 3 4 .1 3 6 0 .0 2 5 6 0 .0 8 4 2 3 0 2 0 .1 9 4 6 3 0 5 2 .3 6 7 1 (0 .6 9 ) (0 .6 8 ) (0 .6 9 ) (0 .6 9 ) (0 .0 1 ) (0 .6 9 ) 1 3 2 7 5 4 4 9 – 1 0 /4 1 8 2 3 8 3 .8 4 2 7 0 .0 1 1 3 0 .0 4 1 4 1 4 6 5 0 .1 2 3 7 1 1 4 0 3 .0 3 2 5 6 (0 .4 3 ) (0 .4 3 ) (0 .4 4 ) (0 .4 3 ) (0 .7 0 ) (0 .4 4 ) 1 4 1 4 1 6 8 1 1 , 1 5 – 1 6 /4 1 2 1 2 9 5 .6 2 9 0 .0 0 6 9 0 .0 2 4 4 2 1 1 0 .0 3 4 6 3 4 6 1 .4 4 6 9 (0 .5 6 ) (0 .5 9 ) (0 .6 0 ) (0 .5 6 ) (0 .2 2 ) (0 .6 0 ) 1 5 1 3 2 5 6 1 8 /4 5 5 3 5 .5 8 0 0 0 0 0 0 0 0 1 6 2 1 4 8 1 9 /4 3 1 3 7 .4 7 0 0 0 0 0 0 0 0 to ta l 1 2 5 6 3 4 1 1 2 1 0 6 7 3 .9 1 1 1 1 0 .0 1 0 8 0 .0 3 3 7 5 2 9 8 0 .0 9 8 1 4 2 4 9 2 .9 1 1 7 7 3 (0 .2 9 ) (0 .4 2 ) (0 .4 3 ) (0 .2 9 ) (0 .2 0 ) (0 .4 3 ) the effect of sea-ice loss on beluga whalesm.p. heide-jørgensen et al. polar research 29 2010 198–208 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 203 previous surveys have used an index for backward compatibility with the 1981 and 1982 strip census surveys. this assumes constant sightability within a strip width of 700 m on either side of the aircraft, and a simple sum of sightings rather than a pod size extrapolation of sightings. within the two strata (west of disko bay and store hellefiske bank) covered in previous surveys, the index value was 1146 belugas (cv = 0.25, 95% ci 708–1855). trends in abundance the abundance estimate of 10 595 (cv = 0.43) belugas from 2006 represents a modest increase in abundance since 1999, when the last abundance estimate of 7941 (cv = 0.32) belugas was derived. the two estimates are not significantly different. similarly, the index estimate from 2006 was slightly larger, but not significantly larger, than the estimates from 1998 (929, 95% ci 563–1533) and 1999 (735, 95% ci 436–1239) (heide-jørgensen & acquarone 2002). when comparing the population trajectory to the catch series for the period 1970–2006 it appears that the recent abundance estimates represent a slight recovery from the population decline observed over the past 25 years (fig. 4). changes in sea ice in the beluga wintering area during winters in the period 1979–2006 the pack-ice edge (>85% sea-ice concentration) reached the coast of west greenland at approximately 66.9°n (heidejørgensen et al. 2007). at the time of its maximum extent the winter sea ice in baffin bay and davis strait usually leaves a stretch of open water along greenland’s west coast, extending from south-west greenland to disko bay, with dense pack ice (>85%) prevailing north of 66.9°n. however, since 2002 the eastern part of baffin fig. 3 detection probability of the pooled detections from both rear and front observers. the distances of sightings were truncated at 1000 m. fig. 4 trends in catches and abundance of belugas in west greenland from 1970 to 2006. catches are shown with a solid line as a twoyear sliding average, and abundance is shown as a dotted line, with squares indicating years where abundance estimates can be derived. the catch data are from heide-jørgensen & rosing-asvid (2002; “medium option” and no ice entrapments) and greenland institute of natural resources (unpubl. data). abundance estimates are from heide-jørgensen & acquarone (2002) and this study, and were derived from a population model presented in alvarez-flores & heide-jørgensen (2004). a quota was established to regulate the catch in 2006. the effect of sea-ice loss on beluga whales m.p. heide-jørgensen et al. polar research 29 2010 198–208 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd204 bay and davis strait has experienced a dramatic decline in the extent of winter pack ice. during the survey in 2006 the extent (46 560 km2) was less than 50% of the average sea-ice coverage during the years with surveys between 1981 and 1999 (94 895 km2). in 2007 and 2008 the extent of sea ice in baffin bay partly recovered to similar levels observed before 2002 (fig. 5). trends in the geographic position of the wintering concentration of belugas the mean longitude of the beluga sightings has no trend between 1981 and 1999, but in 2006 it moves further west, and it almost recovers the original position in 2008 (fig. 5). the change in mean longitudinal position of the whales was significantly correlated with the extent of sea ice (anova, p = 0.0006), so it appears that the effect was mainly driven by the reduced and westward retraction of sea ice that was encountered in 2006. the survey in 2008 encountered sea-ice extension similar to pre-2002 levels, and the belugas were again concentrated in the more eastern area, where they were previously found (fig. 2). trends in catches of belugas in relation to sea ice in 1954–2006 belugas are hunted coastally along west greenland, and the catches during the period 1954–2006 are positively correlated (r2 = 0.28) with the annual midwinter extension of sea ice. the largest catches are observed in years with heavy ice coverage along the west greenland coast (fig. 6). a special form of beluga hunting occurs when the whales are entrapped in sea ice (sassat), but this type of event has not been observed in years with less than 70 000 km2 of midwinter sea-ice extent along west greenland during the period 1951–2006. fig. 5 time trends of sea-ice coverage in west greenland and the average longitude of beluga sightings (between 67 and 70°n and east of 56°w) during midwinter surveys between 1981 and 2008 (r2 = 0.79). sea-ice data are from the “medium area” of west greenland in stern & heide-jørgensen (2003), and were updated through 2008. fig. 6 the correlation between catches of belugas and midwinter sea-ice extent in west greenland (r2 = 0.28). the slope of the regression is significant (anova, p < 0.0001). sea-ice data are from the “medium area” of west greenland in stern & heide-jørgensen (2003), and were updated through 2006. catch data are from the medium option without ice entrapments from heide-jørgensen & rosingasvid (2002), and were updated through 2006. the effect of sea-ice loss on beluga whalesm.p. heide-jørgensen et al. polar research 29 2010 198–208 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 205 discussion changes in distribution and the effect of sea ice the distribution of beluga whales based on sightings from the survey in 2006 shares three characteristics with previous surveys. first, the stratum on store hellefiske bank was clearly the most important area for belugas in west greenland. in 2006, approximately 50% of the total abundance was found in this area, compared with the average between 1981 and 1999 of 41% (range 15–51%). second, no belugas were found inside disko bay, agreeing well with the distribution from past surveys. third, belugas found in the northern part of vaigat confirm that this is an important wintering area, agreeing well with past survey results. there are important differences between the distribution of belugas in the 2006 survey and previous years. the area south of store hellefiske bank had no sightings of belugas in 2006, and contributed nothing to the overall abundance estimate. in contrast, all eight surveys conducted in the period 1981 to 1999 had sightings in this area (heide-jørgensen et al. 1993; heide-jørgensen & reeves 1996; heide-jørgensen & acquarone 2002), suggesting that the distribution of belugas in west greenland has shifted northward. the average contribution to the total abundance from this area in the previous surveys was 38% (range 14–67%). in contrast, about 43% of the total abundance estimate in 2006 came from areas located north of disko island. the surveys in 1982 and 1990 attempted to survey parts of these northern areas; however, searches north of disko bay were abandoned because of a lack of sightings north of vaigat, and because of heavy sea-ice coverage. the decline in sea-ice coverage of the eastern part of baffin bay between 2002 and 2006 probably provided belugas access to a larger area, and allowed the wintering stock to be more widely dispersed over the banks of west greenland. in the surveys before 2006, extensive sea-ice coverage only provided open water for the belugas along the coast south of disko island and in the polynya in vaigat, and restricted both the areas belugas could use as well as the areas that were considered important to survey for belugas. in 2008 it could be observed that the westward transition of the belugas was reversible with the recovery of sea-ice extension in 2007 and 2008. the changes in sea-ice conditions in west greenland have been dramatic, especially after 2002, when about half the midwinter ice disappeared compared with the ice coverage between 1981 and 2002. this change in springtime physical conditions happened directly over the wintering ground for belugas in baffin bay, and has evidently affected the distribution of the whales. the formation of sea ice forces the whales closer to the coast in more restricted areas, where they can be targeted by local inuit hunters and where they are picked up by the surveys. with the loss and westward retraction of sea ice, belugas have followed the ice over deeper water towards the edge of the banks. local observations have noted the absence of whales in coastal areas during 2002–06, and it is also evident that there is a reduced availability for the coastal hunt of belugas. the opening of sea ice along the coast has also allowed a large number of belugas to travel north in spring towards upernavik, to an area inaccessible to hunters, where they are not known to be found early in spring. trends and abundance estimates the declining abundance of belugas in west greenland has been observed from 1981 to 1999 (heide-jørgensen & acquarone 2002). the population in 2000 was estimated to number only 22% of its size in 1954, and the decline was attributed to overharvesting (alvarez-flores & heide-jørgensen 2004). the period from 1979 to 2001, when the decline was detected, had a slightly increasing sea-ice concentration in eastern baffin bay/west greenland, of 3.5% per decade (stern and heide-jørgensen 2003). during this period a smaller area of open water was available for belugas wintering in west greenland, restricting the whales to the coastal areas captured by the surveys. this was demonstrated in the survey in march 1981, when no belugas were detected in the offshore areas of baffin bay (heide-jørgensen et al. 1993). also, satellite tracking of belugas fitted with transmitters in 2001 showed their fidelity to coastal areas in west greenland (heide-jørgensen et al. 2003). during the period of population decline the ice coverage was relatively constant or slightly increasing. the beluga decline is therefore unlikely to be linked to sea-ice changes. in 2006 the ice conditions had changed dramatically, with the consequence being that the belugas were spread out over a larger area, seeking the edge of the offshore banks. the decline in ice coverage in 2006 also left an area almost twice as large as previous years to be surveyed. interestingly, in 2008 ice coverage again increased, and the belugas were more coastal in their central distribution than in 2006, although their abundance could not be estimated. the total abundance corrected for both perception and availability bias was 10 595 belugas (95% ci 5260– 26 400). the latest survey of belugas in west greenland was conducted in 1998 and 1999, and the similarly fully corrected abundance estimate was 7941 belugas (95% ci 3650–17 278) (heide-jørgensen & acquarone 2002). this value is not statistically different from the result from the effect of sea-ice loss on beluga whales m.p. heide-jørgensen et al. polar research 29 2010 198–208 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd206 the current survey, despite the fully corrected point estimate being higher. factors that might have contributed to the recent increase in the abundance of belugas in west greenland include a decline in catches since the mid-1990s. catches have been below 500 per year since 1999, and a new quota installed in 2004 limited the catches to 160 whales per year, considerably less than the average catch level off 688 belugas per year in the 1990s. furthermore, no ice entrapments of belugas have been observed since 1990, which suggests a reduction in large-scale natural mortality events. conclusion the time series on beluga locations in winter in west greenland presented here was not collected with the purpose of observing the effects of climate change on beluga habitat selection. nevertheless, it is one of the few time series of winter occurrence of arctic whales that goes sufficiently far back in time to assess the situation before the dramatic sea-ice recession. the migratory pattern of the belugas seems to be shaped by the annual cycle in freeze-up and sea-ice retraction over longer time periods. it is clear that the belugas that winter in west greenland prefer to stay close to the edge of the pack ice, and that they utilize any loosening in the pack ice to move further north or further west to more offshore areas. it is nevertheless difficult to predict what will happen in the future given that sea-ice coverage increased slightly until 2002, after which time it showed a dramatic decline through 2006, but partially recovered in 2008. so there is currently no monotonic trend on which to base predictions. if the recovery in sea ice continues then the situation will return to “normal”, i.e., the situation observed in the1980s. if a decline in sea-ice distribution continues the whales are expected to be more widespread in the offshore areas of davis strait–baffin bay in the future. belugas seem to be able to respond well to largescale habitat changes. global warming and sea-ice declines may pose less of a problem for belugas than to other arctic marine mammals. acknowledgements the observers fernando ugarte, karolina platou larsen, arne geisler and aili labansen are gratefully acknowledged for their contribution. air greenland and several skilled crews operated the twin otter. the survey in 2006 was funded by the greenland institute of natural resources. the aerial survey in 2008 was funded by the us national aeronautics and space administration, and funding for the red hen recording system was obtained from the vetlessen foundation. hs acknowledges support from the us national science foundation. references alvarez-flores c. & heide-jørgensen m.p. 2004. risk assessment of the beluga (delphinapterus leucas) harvest in west greenland. ices journal of marine science 61, 774–786. borchers d.l., laake j.l., southwell c. & paxton c.g.m. 2006. accommodating unmodelled heterogeneity in double-observer distance sampling surveys. biometrics 62, 372–378. buckland s.t., anderson d.r., burnham k.p., laake j.l., borchers d.l. & thomas l. 2001. introduction to distance sampling: estimating abundance of biological populations. new york: oxford university press. comiso j.c. 1995. ssm/i sea ice concentrations using the bootstrap algorithm. nasa reference publication 1380. greenbelt, md: goddard space flight center. comiso j. 2006. abrupt decline in the arctic winter sea ice cover. geophysical research letters 33, l18594, doi: 10.1029/ 2006gl027341. heide-jørgensen m.p. & acquarone m. 2002. size and trends of the bowhead, beluga and narwhal stocks wintering off west greenland. scientific publications of the north atlantic marine mammal commission 4, 191–210. heide-jørgensen m.p. & laidre k.l. 2004. declining extent of open water refugia for top predators in baffin bay and adjacent waters. ambio 33, 488–495. heide-jørgensen m.-p., lassen h., teilmann j. & davis r.a. 1993. an index of the relative abundance of wintering belugas, delphinapterus leucas, and narwhals, monodon monoceros, off west greenland. canadian journal of fisheries and aquatic sciences 50, 2323–2335. heide-jørgensen m.p. & reeves r.r. 1996. evidence of a decline in beluga abundance (delphinapterus leucas) off west greenland. ices journal of marine science 53, 61–72. heide-jørgensen m.p., richard p., dietz r., laidre k.l. & orr j. 2003. an estimate of the fraction of belugas (delphinapterus leucas) in the canadian high arctic that winter in west greenland. polar biology 23, 318–326. heide-jørgensen m.p. & rosing-asvid a. 2002. catch statistics for belugas in west greenland 1862 to 1999. scientific publications of the north atlantic marine mammal commission 4, 127–142. heide-jørgensen m.p., stern h. & laidre k. 2007. dynamics of the sea ice edge in davis strait. journal of marine systems 67, 170–178, doi: 10.1016/j.jmarsys.2006.10.011. innes s., heide-jørgensen m.p., laake j., laidre k.l., cleator h., richard p. & stewart r.e.a. 2002. surveys of belugas and narwhals in the canadian high arctic in 1996. scientific publications of the north atlantic marine mammal commission 4, 169–190. the effect of sea-ice loss on beluga whalesm.p. heide-jørgensen et al. polar research 29 2010 198–208 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 207 laake j.l. & borchers d.l. 2004. methods for incomplete detection at distance zero. in s.t. buckland et al. (eds.): advanced distance sampling. pp. 108–189. oxford: oxford university press. laake j., calambokidis j., osmek s.d. & rugh d.j. 1997. probability of detecting harbour porpoise from aerial surveys: estimating g(0). journal of wildlife management 61, 63–75. laidre k.l., stirling i., lowry l.f., wiig ø., heide-jørgensen m.p. & ferguson s.h. 2008. quantifying the sensitivity of arctic marine mammals to climate-induced habitat change. ecological applications 18, s97–s125. mclaren i.a. 1961. methods for determining the numbers and availability of ringed seals in the eastern canadian arctic. arctic 14, 162–175. pollock k.h., marsh h.d., lawler i.r. & alldredge m.w. 2006. estimating animal abundance in heterogeneous environments: an application to aerial surveys for dugongs. journal of wildlife management 70, 225–262. richard p.r., hobbs r.c., laake j.l., heide-jørgensen m.p., asseli n. & cleator h. in press. baffin bay narwhal population distribution and numbers: aerial surveys in the canadian high arctic, 2002–2004. arctic. serreze m.c. & francis j.a. 2006. the arctic amplification debate. climate change 76, 241–264, doi: 10.1007/ s10584-005-9017-y. stern h.l. & heide-jørgensen m.p. 2003. variability of sea ice in baffin bay and davis strait. polar research 22, 11–18. thomas l., laake j.l., strindberg s., marques f.f.c., buckland s.t., borchers d.l., anderson d.r., burnham k.p., hedley s.l., pollard j.h., bishop j.r.b. & marques t.a. 2006. distance 5.0. st. andrews: research unit for wildlife population assessment, university of st. andrews. the effect of sea-ice loss on beluga whales m.p. heide-jørgensen et al. polar research 29 2010 198–208 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd208 research note two observations of pumice levels from the west coast of spitsbergen o'ito salvigsen salvigsen, 0. 1984: two observations of pumice levels from the west coast of spitsbergen. polar research 2 n.s., 115-116. otto saloigsen, norsk polarinstitun, rolfstangoeien 12, i330 oslo lufthaon, norway. during the summer of 1983 pumice was observed on raised beaches in two localities on the west coast of spitsbergen. this is an area where pumice has not been reported (salvigsen 1984), and a preliminary note should therefore be of interest. a . pumice pieces were observed in three fig. 1. midterhuken between van mjenfjorden and van keulenfjorden where pumice is abundant in two major zones on the raised beach ridges in van keulenhamna (b). photo: norsk polarinstitutt s 36 3178. 116 otto salvigsen places between russekeila and kapp linn6 in the outermost part of isfjorden. only 5-10 pieces were observed in each place, and their elevations, between 8.9 and 9.9 m, were determined by pre cise leveling. b. during a 14 hours stay in van keulen hamna, between van keulenfjorden and van mijenfjorden, a traverse was examined covering a 20 to 30m wide swath from the shore t o the highest point of strandvollsletta (meaning beach ridge plain) (fig. 1). three levels of pumice were found. a quick leveling with a hand-held instru ment and counting of pumice pieces gave the following result: 1. 5 pieces at approximately 4.5 m above sea level. 2. 33 pieces between 6.7 and 7.7m above sea level. 3. 96 pieces between 10.2 and 11.5 m above sea level. many of the pieces in the highest level were large, ice level in outer isfjorden can be correlated with the main pumice level in svalbard with an age of about 6500 years b.p. the new observations indicate that large amounts of pumice must have drifted ashore also on the western coast of svalbard during the hol ocene. where conditions have been favourable for preservation of pumice, pumice levels can be found and be useful for correlation of raised shorelines. pumice is generally found in two major zones in inner isfjorden (salvigsen 1984), and the observations from van keulenhamna indicate that the same pattern exists on the west coast of spitsbergen. reference salvigsen, 0. 1984: occurrence of pumice on raised beaches and holocene shoreline displacement in the inner isfjorden about 15 cm in diameter. this level and the pumarea, svalbard. polar resedrch 2 n.s., 107-113. quaternary chronostratigraphy of south spitsbergen a m 2 0-. leszek lindner, leszek marks a n d kazimierz pckala s o u t h s p 180 stages ' ' lindner, l., marks, l. & pqkala, k. 1987: quaternary chronostratigraphy of south spitsbergen. polar research 5 n . s . , 21s274. leszek lindner and leszek marks, institute of geology, warsaw university. zwirki i wigury 93. 02489 warsaw, poland; kazimierz pgkala, institute of the earth sciences, m. curie-sklodowska university, akademicka 19, 2 w 3 3 lublin, poland. recent detailed investigations of quaternary sediments in south spitsbergen enabled us to choose several key areas in this region (lindner et al. 1984, 1986; butrym et al. 1987). samples collected in these areas were thermoluminescence and radio carbon dated, and applied for a chronostratigraphic scheme of the quaternary for this part of svalbard (fig. 1). marine clays of the torellkjegla interglacial are the oldest deposits in this region. they were dated at holstein, in 413-383 ka b.p. in the torellkjegla section. they are glaciotectonically deformed together with the overlying glacial sediments. the younger wedel jarlsberg land glaciation is well documented by two tills, dated at saalian 313-284 ka b.p. and 229-189 ka b.p., respectively. the younger till is accompanied by glacio fluvial sands and gravels which were dated at 222-141 ka b.p. a final part of the wedel jarlsberg land glaciation is documented by glaciofluvial deposits, dated at 161 ka b.p. they are superposed by a weathering-soil horizon that is dated at 143 ka b.p. in the bogstranda section. according to the authors i t s ~ b e r 1 \ i i ---- -1llka. .143ka--j i 161 ka 0 ------- \ i i i i i glaciation 28lkab 313ka. 1 383ka. i \ 1 '2 i x 0 2 6 k a x 075ka x o8oka x l l l k a c w 0 x 1 8 3 k a 0 d 0 763ka i 8 6 0 k a x 8 8 6 k a \i i x 9 l 7 k a x 9.89 ko =t x 0.81 ka j x 156ka r--- x 8 6 8 k a l i i 1 ls-lisbetdalen stage, ss-slaklidalen stage, lia-little ice age fig. 1 . chronostratigraphic subdivision of the quaternary of south spitsbergen: black dots mark thermoluminescence dates and crosses radiocarbon dates. 274 leszek lindner. leszek marks & kazirnierz pqkala this horizon represents the bogstranda (= eemian) interglacial. the sorkapp land (= weichselian) glaciation is the youngest pleistocene glaciation in south spitsbergen. i t is defined by three or four glacial stades. three younger ones are expressed by tills and glaciofluvial sediments, dated at about 73 ka b.p., 5 m 1 ka b.p. (lisbetdalen stage) and 29.5-22 ka b.p. (slakli dalen stage). respectively. two interstades are represented by marine sediments dated at 88-87 ka b.p. and 63 ka b.p. during the younger interstade a paleosol developed in the sofiebreen section; it separates tills which were dated at 5 m 3 . 6 ka b.p. and 29.5 ka b.p. the early holocene warming is represented by marine sedi ments, mollusc shells which were dated at 10.1-8.6ka b.p. during the holocene there were 2-3 glacial advances. the first one occurred about 8 ka b.p. as proved by radiocarbon dates of glacier-redeposited mollusc shells on treskelen. the second advance is represented probably by glacial sediments in rev dalen, although they could have been deposited during the first early holocene glacial advance. the late holocene glacier retreat (about 1 . 6 4 . 6 k a b.p.) is proved by numerous radio carbon data. the last glacial advance (little ice age) started about 0.6 ka b.p. in south spitsbergen. a maximum extent of glaciers from this time is delimited by present ice-cored moraines. a retreat of the glaciers from the ice-covered moraines started at the end of the 19th century. distinguished main chronostratigraphic units of south spits bergen can be tentatively correlated with those recorded in other parts of svalbard (cf. mangerud & salvigsen 1984: miller 1982). references butrym. j . . lindner, l., marks, l. & szczpny, r. 1987: first thermoluminescence datings of pleistocene sediments from serkapp land, spitshergen. pol. polar res. 8, 217-229. lindner, l., marks, l. & pqkala. k . 1984: late quaternary glacial episodes in the hornsund region of spitsbergen. boreaf 13. 35-47. lindner, l., marks, l. & pqkala. k. 1986: outline of quat ernary chronostratigraphy of the northern hornsund area, southern spitsbergen. bull. pol. ac. earrh sc. 3 4 . 427-436. mangerud, j . & salvigsen, 0. 1984: the kapp ekholm section, billefjorden, spitshergen: a discussion. boreas 13, 155-157. miller, g . h. 1982: quaternary depositional episodes. western spitsbergen. norway: arninostratigraphy and glacial history. arctic and alpine res. 14, 321-340. no job name contrasting climate change in the two polar regionspor_128 146..164 john turner1 & jim overland2 1 british antarctic survey, high cross, madingley road, cambridge cb3 0et, uk 2 pacific marine environment laboratory, national oceanic and atmospheric administration, 7600 sand point way ne, seattle, wa 98115, usapor_128 146..164 abstract the two polar regions have experienced remarkably different climatic changes in recent decades. the arctic has seen a marked reduction in sea-ice extent throughout the year, with a peak during the autumn. a new record minimum extent occurred in 2007, which was 40% below the long-term climatological mean. in contrast, the extent of antarctic sea ice has increased, with the greatest growth being in the autumn. there has been a large-scale warming across much of the arctic, with a resultant loss of permafrost and a reduction in snow cover. the bulk of the antarctic has experienced little change in surface temperature over the last 50 years, although a slight cooling has been evident around the coast of east antarctica since about 1980, and recent research has pointed to a warming across west antarctica. the exception is the antarctic peninsula, where there has been a winter (summer) season warming on the western (eastern) side. many of the different changes observed between the two polar regions can be attributed to topographic factors and land/sea distribution. the location of the arctic ocean at high latitude, with the consequently high level of solar radiation received in summer, allows the icealbedo feedback mechanism to operate effectively. the antarctic ozone hole has had a profound effect on the circulations of the high latitude ocean and atmosphere, isolating the continent and increasing the westerly winds over the southern ocean, especially during the summer and winter. keywords annular modes; antarctic; arctic; climate change; ozone hole. correspondence john turner, british antarctic survey, high cross, madingley road, cambridge cb3 0et, uk. e-mail: j.turner@bas.ac.uk doi:10.1111/j.1751-8369.2009.00128.x the fourth assessment report of the intergovernmental panel on climate change (ipcc) indicated that some of the largest climatic changes over the next century are expected to occur at high latitudes (solomon et al. 2007). on this time scale, if concentrations of greenhouse gases continue to rise at the present rate, we can expect a large reduction in sea-ice extent in both polar regions, broadscale warming across the arctic and antarctic and greater high-latitude precipitation. however, over recent decades the changes observed in the two polar regions have been markedly different. whereas the extent of late summer season sea ice in the arctic has reached record minima, the antarctic sea ice has increased in extent by a small amount. near-surface air temperatures have increased in many parts of the arctic, yet temperatures across much of the antarctic have actually decreased, but with the antarctic peninsula warming at a rate as high as observed anywhere in the southern hemisphere. there is increasing evidence of enhanced melting on the periphery of greenland, yet the antarctic ice sheet appears to be essentially in balance. the forcing by shortwave radiation is very similar in the two polar regions, and greenhouse gas concentrations are essentially the same in both areas. so the contrasting changes that have taken place must be a result of differences in the topography and land/sea distribution of the two regions, which result in markedly different atmospheric and oceanographic conditions, along with factors specific to each area, such as the major depletion of stratospheric ozone that has occurred above the antarctic. in this paper we document the climatic changes that have taken place in recent decades, and consider our current knowledge of the mechanisms responsible for the changes. we also suggest future research needs. polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd146 mailto:turner@bas.ac.uk the coupled elements of the polar climate systems although record-breaking climatic events, such as the new minimum in arctic sea-ice extent in september 2007, and the very large increase in surface temperature on the western side of the antarctic peninsula over the last 50 years, receive a great deal of attention in both scientific and popular literature, they should not be considered in isolation. research in recent years has shown the highly coupled nature of the polar environments, with the atmosphere, ocean and cryosphere often playing a role in concert in establishing anomalous conditions. for example, changes in the atmospheric circulation can result in anomalies in the sea-ice extent, which in turn can affect the salinity of the ocean. whereas atmospheric anomalies can be quite shortlived, changes to the ocean can persist for long periods, so that understanding individual events can require the consideration of changes in the whole system over an extended period. a factor that has played a role in many of the atmospheric and oceanic changes observed at high latitudes in recent years has been shifts in the large-scale modes of variability of the climate system (stammerjohn, martinson, smith, yuan et al. 2008). studies of atmospheric analyses have shown that the principal modes of variability in the atmospheric circulation of the extratropics consist of oscillations of mass (as measured by surface barometric pressure) between high and mid-latitudes (thompson & wallace 2000). these can be observed as anomalies of opposite sign in mean sea-level pressure (mslp), with periods of positive (negative) anomalies at high latitudes (mid-latitudes) developing before the anomalies reverse. these anomalies have a near-zonally symmetric or annular structure, and are known as the southern annular mode (sam; also known as the highlatitude mode or the antarctic oscillation) and the northern annular mode (nam, which is related to the north atlantic oscillation) in the south and north, respectively. the nam and sam can be seen in many parameters measured at high latitudes besides surface pressure, including temperature, geopotential height and zonal wind. when the annular modes are more positive, atmospheric pressures are lower at high latitudes and higher in mid-latitudes, which results in a strengthening of the westerly winds. changes in the annular modes can therefore have major implications for oceanographic conditions. observational and modelling studies have shown that the sam contributes a large proportion (ca. 35%) of the southern hemisphere climate variability on a large range of timescales, from daily (i.e., baldwin 2001) to decadal (kidson 1999), and is also likely to drive the large-scale circulation of the southern ocean. an index of the sam has been constructed from the pressure difference between the latitudes 40°s and 65°s (marshall 2003), allowing its changes since 1957 to be investigated. the record can be extended further back using proxy data, such as the tree-ring record (jones & widmann 2003). it is possible to examine much longer-term changes in the nam as meteorological observations from around the north atlantic are available dating back to around the middle of the 19th century. the two polar regions are also affected by a number of different modes of variability (simmonds 2003; yuan & li 2008). tropical atmospheric and oceanic conditions can affect high latitudes, with signals of the el niño– southern oscillation (enso) being transferred polewards via the pacific south american association (psa) (simmonds & jacka 1995; yuan & martinson 2000; yuan 2004) and the pacific north american association (pna) (turner 2004). these two modes are characterized by a series of alternating positive and negative mean sea-level pressure anomalies, extending from the west-central equatorial pacific into both hemispheres. high–low latitude links that operate on longer time scales also exist, such as the pacific decadal oscillation (pdo) (zhang et al. 1997). the pdo is important in influencing the climate of alaska, and changes in the pdo have been linked to the recent warming across the region. it has even been shown to modulate antarctic precipitation (monaghan & bromwich 2008). the impacts from the positive and negative phases of the pna and nam can act independently or simultaneously in any given winter, with trends in arctic cyclones and variations influencing sea-ice cover (simmonds et al. 2008). as the pna and nam represent less than 50% of the interannual mslp variability, a third type of pattern can arise, such as the anomalous meridional flow into the western arctic observed in the first part of the 21st century (overland et al. 2008). the psa has a strong influence on the climate of the antarctic peninsula/southern south america region, whereas the pna affects the aleutian low. conditions in the tropical indian ocean have also been linked to climatic change in the north atlantic (hoerling et al. 2001; hoerling et al. 2004). however, the robustness of these statistical links (teleconnections) can change over time (fogt & bromwich 2006), so that very similar tropical el niño or la niña events can give quite different extratropical responses. there are also interactions between the sam and enso that further complicate the linkages of the tropical and high-latitude climates. however, there is still debate over links between the enso and the nam (quadrelli & wallace 2002). climate change in the two polar regionsj. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 147 recent changes in the polar environment atmospheric circulation the arctic. in the northern hemisphere, we have a long record of the variations in the nao/nam (fig. 1a). in the late 19th and early 20th centuries there were fluctuations in the index, and periods of positive anomaly, such as around 1910, but no overall trend. the most marked trend has been from the mid-1960s to the mid-1990s, when the index shifted from a large negative to a large positive anomaly. this change resulted in a strengthening of the mid-latitude westerlies, and the advection of warm air from the north atlantic into the arctic ocean and northern russia. as in the south, increasing levels of greenhouse gases can shift the nam into its positive phase. however, since the mid-1990s, at a time of record levels of greenhouse gases, the nam has reverted to more neutral conditions, indicating the complex nature of climate change. the arctic has not experienced the level of stratospheric ozone loss that has been observed in the antarctic, as there is more meridional heat transport in the north, and hence stratospheric temperatures are not fig. 1 (a) the winter season north atlantic oscillation index based on station data. the thick line is the 5-year running mean. (data from the climate and global dynamics group, national center for atmospheric research, boulder, co, usa.) (b) monthly values of the southern annular mode (sam) index. the thick line is a 12-month running mean. (from http:// www.antarctica.ac.uk/met/gjma/sam.html; figure courtesy of dr gareth marshall, british antarctic survey.) climate change in the two polar regions j. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd148 http://www.antarctica.ac.uk/met/gjma/sam.html http://www.antarctica.ac.uk/met/gjma/sam.html cold enough for large-scale ozone destruction. however, there has been some ozone loss, and volodin & galin (1999) found a link between ozone depletion and nam trends. this finding has not been reproduced in other models, and simulations forced by randel & wu’s (1999) ozone trends did not show a significant northern hemisphere circulation response, suggesting that the much weaker ozone depletion observed in the northern hemisphere has not been an important driver of circulation changes there. the aleutian low is one of the main features of atmospheric circulation in the northern hemisphere during winter, with a controlling influence on north pacific ocean circulation, bering strait sea-ice extent and western north american surface climate (zhu et al. 2007). there has been a statistically significant 20th century shift to a deeper and more poleward winter aleutian low, which has been attributed to anthropogenic greenhouse gases and sulphate aerosols (fyfe, pers. comm. 2008). the antarctic. the sam and nam change as a result of natural climate variability, and also in response to various anthropogenic forcing factors. since 1957 the sam has shifted to more positive conditions (fig. 1b), with the largest change being during the summer and autumn seasons. marshall et al. (2004) demonstrated that the upward trend in the summer sam index during recent decades is inconsistent with simulated internal variability in the hadley centre general circulation model, which suggests an external cause. experiments with climate models have suggested that the sam has changed most because of the development of the antarctic ozone hole (sexton 2001; gillet & thompson 2003). the polar vortex is most pronounced in the winter stratosphere, when the air above the continent is extremely cold. the destruction of stratospheric ozone above the antarctic mostly takes place during the spring (farman et al. 1985), thereby cooling the stratosphere and strengthening the polar vortex at this level during this season. but the loss of springtime ozone as a result of the “ozone hole” has also cooled the stratosphere through the summer months. this in turn has resulted in a lower mean sea-level pressure in the antarctic at this time of year, thereby shifting the sam into its positive phase (thompson & solomon 2002). the changes in the sam have resulted in a poleward contraction, and an increase of about 20% in the strength of the circumpolar westerly winds during autumn. in addition, the shift to a positive phase of the sam has given weakened descent and colder temperatures over most of antarctica, and has increased the production of coastal sea ice. increasing concentrations of greenhouse gases have also been shown to move the sam into its positive phase (fyfe et al. 1999; kushner et al. 2001; stone et al. 2001). however, model experiments suggest that the increase of greenhouse gases make a smaller contribution to the change than stratospheric ozone depletion (arblaster & meehl 2006). since the late 1970s, el niño events have become more frequent and stronger. however, it has been difficult to find high-latitude climate changes than can be attributed to these alterations in the tropical circulation. around the antarctic, a shift to more el niño events would tend to promote a stronger psa pattern, with more highpressure/blocking events to the west of the antarctic peninsula. however, the available atmospheric analyses would suggest that there has been the reverse of this trend, with more storms in the area, again indicating the highly nonlinear links between the highand lowlatitude areas. pezza et al. (2008) have recently proposed that there is an organized hemispheric cyclone pattern associated with the enso, the sam, sea-ice extent and rainfall anomalies in southern australia. they suggest that the sam and sea-ice extent are interlinked as part of a complex physical system that is best understood as a coupled mechanism. ocean circulation and water masses the arctic ocean. detecting changes in ocean circulation and water masses is more difficult than detecting changes in the atmosphere because of the lack of in situ observations in earlier decades. for example, no data exist from large areas of the southern ocean prior to the 1950s, a problem that persisted up to the advent of the satellite era in the 1970s and 1980s. nevertheless, some indications of change are apparent. some of the largest oceanic changes have been observed in the arctic ocean. here, there has been an increase in river discharge into the ocean from northern eurasia since the mid-1930s, which has contributed to a marked freshening of the ocean (peterson et al. 2008). this has happened in parallel with rising air temperatures (johannessen et al. 2004), and greater snowfall across eurasia when the nam was in its positive phase (min et al. 2008). but there has been decreasing river discharge in eastern canada over the period 1964–2003, probably also tied to trends in the nam (déry et al. 2005). but on the other side of the continent, the mackenzie river in western canada shows no long-term trend (abdul & burn 2006). discharge trends are greatest in the north, where the permafrost is most extensive and is melting. climate change in the two polar regionsj. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 149 subsurface layers within the arctic ocean are sensitive to the penetration of heat from atlantic water (aw) and pacific water (pw) via the fram and bering straits. expeditions during the 1990s and 2000s measured variations in the heat content of aw, indicating a peak warming near the north pole in 1995, a minimum in 2005 and a new warming pulse thereafter (steele & boyd 1998; morison et al. 2002). during the period 1965–1995, as the nam index rose, warming was observed from aw advection into the barents/kara seas, and from pw advection into the chukchi and western beaufort seas. also during this period, winter sea-ice transport away from the eastern siberian shelves created thin ice that melted quickly during summer, leading to a longer summer open-water period, during which solar energy warmed the ocean. recent ocean surface warming in the beaufort/chukchi/east siberian seas since 2002 seems forced more by shortwave energy absorption than by northward-flowing ocean advection, although more in situ data are needed to confirm this. the southern ocean. over recent decades certain parts of the southern ocean have changed very rapidly, but the pattern and physical nature of the changes are complex, and a number of mechanisms and feedbacks are believed to be implicated. on the large scale, the waters of the antarctic circumpolar current (acc) have warmed more rapidly than the global ocean as a whole. temperature records from autonomous floats drifting at depths of between 700 and 1100 m during the 1990s were collated and examined by gille (2002), who compared these data with earlier shipbased temperature measurements from the 1950s. she identified a large-scale warming of the acc at this depth of around 0.2°c (fig. 2). this work has recently been extended to show that the warming is greatest near the surface, where it has been as large as 1°c. the temperature rise has not been constant, with the records showing a large shift in the upper ocean during the 1960s (gille 2008). it was also suggested that the warming could be a result of a southwards shift of the acc current cores, essentially reflecting a redistribution of heat rather than an overall temperature increase. the reasons for the warming of the circumpolar southern ocean are not known unambiguously, and it is likely that multiple processes may have played a role. the shift of the sam into its positive phase (marshall 2003), with a subsequent increase in eastward wind stress over the southern ocean, and a shift in the band of maximum wind stress southwards, has had a major impact on the marine environment. it has resulted in a reduction in the efficiency of the southern ocean co2 sink, associated with changes in upwelling and mixing (le quéré et al. 2007). the stronger westerlies could also have led to greater ocean eddy activity, and a consequent increase in the poleward eddy heat flux (meredith & hogg 2006; hogg et al. 2008). in addition, based on climate modelling studies, it has been suggested that the stronger winds over the southern ocean may be leading to an acceleration of the acc (hall & visbeck 2002; fyfe & saenko 2006). it has been hypothesized, and supported by coarseresolution climate modelling studies, that the acc may have moved southwards in response to the change in the sam (oke & england 2004; fyfe & saenko 2006), effectively bringing warmer water further south, and leading to an apparent warming. this suggestion is in line with the work of gille (2002). there is good observational evidence that the strength of the acc does depend on the sam on timescales from days and weeks (aoki 2002; hughes et al. 2003) to years (meredith et al. 2004), but there is currently no evidence of a sustained, long-term increase in transport. this may result from the lack of a suitable monitoring system, but available indications do suggest that any change in transport over the past few decades have been small, and typically of the order of only a few sverdrup. fig. 2 regions of warming of the southern ocean at depth (ca. 700– 1100 m) in °c, derived by differencing temperature records from float data collected in the 1990s, with historical data collected by ships in previous decades. (from gille 2003.) climate change in the two polar regions j. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd150 a further process that could have contributed to the warming of the southern ocean is increased atmosphereto-ocean heat flux associated with raised levels of radiative greenhouse gases in the atmosphere, and modelling studies have indicated that the rate of southern ocean warming would have been even higher, but for the masking effects of volcanic and other aerosols (fyfe 2006). south of the acc there are also major changes taking place. a very significant freshening of the waters in the coastal region between the amundsen sea and the adélie coast has been noted in recent decades (jacobs et al. 2002), which could be of a comparable magnitude to the great salinity anomaly of the north atlantic (dickson et al. 1988). the cause of the freshening is believed to involve the increased melt of glacial ice from adjacent regions of antarctica (jacobs et al. 2002), and it has been theorized that the excess heat causing this melt has come from the increasing ocean temperatures (walker et al. 2007). there is also evidence of a change in the hydrological cycle affecting both northern and southern branches of the global meridional overturning circulation. the observed freshening is not confined to the upper layers, but has been identified in some active areas of antarctic bottom water formation, most notably in the ross sea (rintoul 2007). regionally there has been a very strong warming in the ocean areas to the west of the antarctic peninsula, where the summertime surface ocean temperatures have warmed by more than 1°c since the 1950s, with an accompanying increase in salinity (meredith & king 2005). these changes reflect the well-known increase in atmospheric temperature (king 1994) and reduction in sea ice at this location (comiso & nishio 2007). temperature changes the arctic. there is large interannual and decadal temperature variability in both polar regions, which makes detection of trends difficult, especially as the length of the climate records are shorter than those for mid-latitude areas. however, we are fortunate in the arctic in having 59 stations with continuous records of near-surface temperature that start around 1930–1940, with 15 that extend back to 1900 and three that even start in the middle of the 19th century. the temperature records from these 59 stations for january are shown in fig. 3, along with a map indicating the locations of the stations. this figure shows the complexity of temperature changes that take place on a range of timescales. decades of warmer or colder conditions can be found throughout the records, followed by switches back to more average conditions. large anomalies often occur across a range of longitudes, but are very rarely found all the way around the arctic. overall, fig. 3 shows generally warm temperatures for the 1990s, which is consistent with the global trend, whereas over the 1930s–1950s there were more regional/ temporal episodic warm events. the record of arctic temperatures shows that it has warmed twice as much as the global mean warming, but the arctic changes are neither spatially nor temporally uniform. for the central arctic, the largest temperature trends over 1979–1995 occurred in the spring, the next largest trends occurred in winter, and trends for summer and autumn were much smaller (serreze et al. 2000). with a major loss of summer sea ice in 2005–08, the anomalous autumn surface air temperatures are now 5°c above normal over much of the central arctic. in terms of annual mean surface temperature (fig. 4), north-western north america and central siberia have experienced the greatest temperature rises over the last 50 years. the warming across alaska and northern canada is mainly the result of a sudden warming in the mid-1970s, when there was a shift in the nature of the pdo, which deepened the aleutian low, thereby giving warmer conditions across alaska. the antarctic. many of the in situ climate records for the antarctic start around the time of the international geophysical year (igy) in 1957/58, when a number of year-round research stations were established. the 50-year records from these stations indicate the complex temperature changes that have taken place (turner et al. 2005) (fig. 5a). this figure shows a pattern of large warming in the annual mean temperature on the western and northern parts of the antarctic peninsula, with vernadksy (formerly faraday) station having the largest statistically significant (<5% level) trend, at +0.56°c per decade from 1951 to 2000. rothera station, some 300 km to the south of vernadksy, has a larger annual warming trend, but the shortness of the record and the large interannual variability of the temperatures renders the trend statistically insignificant. the region of marked warming extends from the southern part of the western antarctic peninsula north to the south shetland islands, but the magnitude of the warming decreases northwards, away from vernadksy. at orcadas, in the south orkney islands, a 100-year record shows a warming trend of only +0.20°c per decade. most of the antarctic research stations are located around the edge of the continent, and we have the most reliable information on temperature change at these sites. climate change in the two polar regionsj. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 151 however, a number of attempts have been made to extrapolate the trends from the locations of the stations to the data-sparse interior areas of the continent (chapman & walsh 2007; monaghan, bromwich, chapman et al. 2008). figure 5b shows the linear trends in annual mean surface temperature for the period 1958–2002, as determined in the chapman & walsh (2007) study. this highlights the marked contrast in temperature between the antarctic peninsula and the rest of the continent. recently, the available in situ staffed station and automatic weather station temperature observations have been used in conjunction with satellite-derived surface fig. 3 (a) the locations of the 59 stations with long records in the arctic. the station names are provided in overland et al. (2004). (b) surface temperature anomaly values for the 59 arctic weather stations for january, relative to the 1961–1990 mean for each station. (illustrations updated from overland et al. 2004.) climate change in the two polar regions j. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd152 skin temperatures to estimate temperature trends across the interior regions of the continent, where data are sparse (steig et al. 2009). the study found that there had been a significant warming across much of west antarctica, with trends exceeding 0.1°c per decade, with the greatest warming having been during the winter and spring. on a seasonal basis, the largest changes have been a winter (summer) warming on the western (eastern) side of the antarctic peninsula. at vernadksy, the warming fig. 4 linear trends in the annual surface temperature for 1950–2008. (from http:// data.giss.nasa.gov/gistemp/maps/; courtesy of the national aeronautics and space administration/goddard institute for space studies.) fig. 5 (a) annual and seasonal near-surface temperature trends, 1951–2006, for antarctic stations with long in situ records (minimum 35 years). the trends are for the full length of each record. the colours indicate the statistical significance of the trends. trends were computed for the full length of each record. most stations started reporting around the time of the international geophysical year in 1957/58. autocorrelation was taken into account in computing the significance levels. (figure courtesy of dr gareth marshall, british antarctic survey.) (b) linear trends of annual mean surface air temperature (°c per decade) for the period 1958–2002. greens and blues denote cooling; yellows and reds denote warming. significant trends are indicated by hatching (95% single hatching; 99% cross-hatching). (from chapman & walsh 2007.) climate change in the two polar regionsj. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 153 http://data.giss.nasa.gov/gistemp/maps http://data.giss.nasa.gov/gistemp/maps during winter has been 5°c over the last 50 years, and is consistent with the oceanic warming noted earlier. at this location there is a high correlation between the temperature and the winter sea-ice extent over the amundsen– bellingshausen sea, suggesting greater sea-ice cover in the middle of the 20th century, and a progressive reduction since this time. the reasons for the greater sea-ice extent in the 1950s and 1960s are not known with certainty, but may have been linked to weaker/fewer storms to the west of the peninsula, and greater atmospheric blocking. a greater frequency of blocking anticyclones would have meant weaker northerly winds to the west of the antarctic peninsula, allowing the sea ice to advance farther north during the winter, and giving colder temperatures on the western side of the peninsula. at present it is not known whether the western peninsula warming is a result of natural climate variability, or whether it has an anthropogenic origin or component. on the eastern side of the antarctic peninsula the largest warming has been observed during the summer months, and has been associated with the strengthening of the circumpolar westerlies as the sam has shifted into its positive phase (marshall et al. 2006). stronger winds have resulted in enhanced temperature advection and more relatively warm, maritime air masses crossing the peninsula and reaching the low-lying ice shelves. higher temperatures on the ice shelves will also be a result of adiabatic descent and warming of the winds crossing the antarctic peninsula topography. around the rest of the coastal region of the continent there have been few statistically significant changes in surface temperature over the last 50 years (fig. 5a). however, the amundsen–scott station, at the south pole, has shown a statistically significant cooling in recent decades that is thought to be a result of fewer maritime air masses penetrating into the interior of the continent. since the development of the antarctic ozone hole in the early 1980s, the resultant changes in the sam have had a major impact on antarctic temperatures. figure 6 shows the december–may surface temperature trends, and the contribution of the sam to the trends. this shows that over the summer–autumn period, the change of the sam has resulted in a pattern of warming across the antarctic peninsula and a cooling around much of the coast of east antarctica. van den broeke & van lipzig (2004) argued that the reason for the winter cooling over east antarctica during periods of high sam index is the greater thermal isolation of antarctica, resulting from increased zonal flow, decreased meridional flow and an intensified temperature inversion on the ice sheet because of weaker near-surface winds. for the period 1957–2004 the estimated change in antarctic nearsurface temperatures in autumn caused by the upward trend in the sam index exceeds 1.0°c at seven of 14 stations with long records. without the loss of stratospheric ozone over the last 30 years, antarctic warming may well have been more extensive. ice core proxy reconstructions of antarctic surface temperatures provide an extremely important means of extending the climate record back into the preinstrumental period. such data show that in the past few decades the temperatures have moved outside the range of variability established over the past 1200 years (mayewski & maasch 2006). the antarctic radiosonde temperature profiles collected since the igy indicate that there has been a warming of the winter troposphere and cooling of the stratosphere over the last 30 years. the data show that regional midtropospheric temperatures have increased most around the 500-hpa level, with statistically significant changes of 0.5–0.7°c per decade (fig. 7), which is the largest temperature increase at this level on earth. the spatial pattern of the warming can be appreciated from the 500hpa temperature trends in the european centre for medium-range weather forecasts (ecmwf) reanalysis fields (turner et al. 2006), although it should be noted fig. 6 (a) december–may linear trends in surface temperature (1969–2000) and 925-hpa wind (1979–2000). (b) the contribution of the southern annular mode to the trends. (from thompson & solomon 2002. reprinted with permission of the american association for the advancement of science.) climate change in the two polar regions j. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd154 that the trends here are a little larger than in the radiosonde data because of a cold bias in the early part of the reanalysis data set. recently, the antarctic midtropospheric warming has been identified in the satellite microwave sounder unit data (johanson & fu 2007). precipitation there are many problems in measuring solid precipitation at high latitudes, and gauge undercatch is a significant problem, especially in winter. so it is difficult to determine the changes in precipitation over recent decades. but, overall, there does seem to have been a recent increase in precipitation at certain locations, such as central siberia, which is consistent with the positive nam during this period, and the greater penetration of maritime air masses into the region. these trends are more evident from snow-depth records than from precipitation records, but are also consistent with the greater input of freshwater into the arctic ocean. from a modelling point of view, all 21 ipcc fourth assessment report climate models, when run over the second half of the 20th century, have an increasing trend in ensemble mean precipitation across the antarctic (bracegirdle et al. 2008). winter trends are similar to annual means, but summer shows no systematic changes. in the antarctic, the switch of the sam into more positive conditions, with the consequent strengthening of the circumpolar vortex, is thought to have given drier conditions over large parts of west antarctica, the ross ice shelf and the lambert glacier region, and wetter conditions elsewhere (van den broeke & van lipzig 2004). however, in situ measurement of precipitation on the antarctic continent is very difficult, and much of our knowledge of precipitation variability and change has come from ice cores, from which it can be difficult to determine seasonal change. a major study into changes in antarctic accumulation (monaghan et al. 2006) concluded that there had been no statistically significant change in accumulation across the continent since the igy, although there has been variability in the firn (helsen et al. 2008). however, on longer timescales, and for limited areas, there are indications of change. for example, a new ice core from the south-west corner of the antarctic peninsula has shown that there has been a doubling of the accumulation in that region since about 1850 (thomas et al. 2008). fig. 7 trends in the 500-hpa temperature over the period 1979–2001 from the european centre for medium-range weather forecasts 40-year reanalysis, showing tropospheric warming around the 5-km level. the contours are in °c per decade. (from turner et al. 2006. reprinted with permission of the american association for the advancement of science.) climate change in the two polar regionsj. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 155 sea ice the arctic. the marked decrease of arctic sea-ice extent in recent years has been one of the most publicized aspects of polar climate change, and has been widely reported in the popular press as well as the scientific literature. the loss of ice has been greatest in september (fig. 8), with a decrease of over 10% per decade for the period 1979–2006. in september 2007 the extent of arctic sea ice reached a new minimum of 4.1 million km2 (fig. 9), which was 39% below climatology, and some 23% below the previous minimum in 2005. although a progressive decrease of arctic sea ice had been predicted by climate models for a number of years, most scientists were surprised by the dramatic sea-ice decline in 2007. the ice appears to have reached a minimum in 2007 because of a long chain of events stretching back to the 1990s. the age, area and thickness of the ice had decreased in recent years as a result of the “flushing” of much of the ice out of the arctic basin in the early 1990s, which pre-conditioned the decline (nghiem et al. 2007). the nam was particularly strong and positive from 1989 to 1995, which advected a considerable volume of multiyear ice out of the arctic into the atlantic, so that the fig. 8 the annual cycle of percentage change of sea-ice extent in (a) the arctic and (b) the antarctic. based on the national aeronautics and space administration bootstrap sea-ice extent retrieval algorithm. (from turner et al. 2009.) climate change in the two polar regions j. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd156 area of perennial sea ice over the arctic ocean decreased from over 5.6 million km2 to 2.7 million km2, as sea ice drifted away at twice its usual speed. sea ice may reside in the arctic for over 5 years, but it is strongly influenced by the state of the nam, with increased ice advection away from the russian coast during high nam periods, and faster export of sea ice from the pole to the fram strait. during summers with high nam (june–august), ice motion increases the concentration of sea ice, and temperature advection increases the concentration of ice in the chukchi sea, but decreases the concentration of ice in the canadian beaufort sea. the nam peaked around 1989–1995, and since then a more meridional circulation pattern (southerly wind anomalies from the pacific sector) has been present. these nam and meridional flows persisted for multiple years, contributing to large-scale changes in ocean and sea-ice conditions (shimada et al. 2006; steele et al. 2008). despite the switch of the nam to more neutral conditions, the arctic sea-ice extent has continued to decrease, suggesting that the correlation between the nam and arctic climate that characterized the 20th century may now be broken. the recently observed reduction in sea-ice cover in the arctic ocean is not spatially uniform, but rather is disproportionately large in the pacific sector of the arctic ocean. the spatial pattern of ice reduction is similar to the spatial distribution of warm pacific summer water that crosses the upper portion of the halocline in the southern canada basin, north of the chukchi sea. in 2007 the sea-ice minimum was reached as a result of favourable synoptic conditions, with the loss of sea ice on the pacific side resulting from an unusually persistent surface high pressure/southerly wind pattern from june through to august, which transported heat and moisture into the central arctic, north of the bering strait. the high pressure over the beaufort sea produced fewer clouds, but because of the albedo of existing ice cover in this region, it did not impact on the area of major sea-ice loss further to the west (schweiger et al. 2008). the winds also advected sea ice across the central arctic towards the atlantic sector (gascard et al. 2008). a similar pressure pattern also occurred in 1977 and 1987, with no remarkable effect on sea-ice extent. warm pacific water entering the arctic ocean via the chukchi sea also appears to have been important in the 2007 sea-ice minimum. there has been a great deal of debate as to whether the minimum of arctic ice extent in 2007 was a result of anthropogenic factors, or whether it could have occurred because of natural climate variability. there were warmer air temperatures across many high-latitude areas during the 1930s, but there was not a decrease of arctic sea ice on the scale of that seen in the early years of the 21st century. at a workshop on recent highlatitude climate change in seattle in october 2007, the participants concluded that the dramatic arctic sea-ice loss in 2007 was caused by a combination of temperature increases as a result of a greater concentration of greenhouse gases, fortuitous timing in the natural variability of the atmospheric general circulation and positive feedbacks associated with a reduction in sea ice. when run through the 21st century, some of the climate models used in the production of the ipcc fourth assessment report (solomon et al. 2007) do have sea-ice extent decreases of the magnitude observed in recent years, although all the models do this much more slowly than is observed in the real world (stroeve et al. 2007). representing rather small-scale atmospheric and oceanic processes and feedbacks in a climate model is extremely challenging. the antarctic. in contrast to the arctic, the extent of southern hemisphere sea ice has actually increased in the period since reliable satellite data became available in 1979. the increase has been statistically significant, and has been greatest in march (fig. 8b) and in the ross sea sector of the southern ocean. the change in this area had been linked to a stronger cyclonic flow over west antarctica, giving greater southerly flow off the ross ice shelf fig. 9 the minimum arctic sea-ice extent in october 2007 (white area), relative to climatology (purple line). (from fetterer 2002 [updated 2009].) climate change in the two polar regionsj. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 157 (stammerjohn, martinson, smith & iannuzzi 2008). this change in circulation was reflected in the ecmwf 40-year reanalysis (era-40) and the ar4 models run through the late 20th century. experiments with an atmosphere-only model have pointed to the springtime decrease of stratospheric ozone as playing a major role in changing the atmospheric circulation over the amundsen sea (turner et al. 2009). the ice sheets the greenland ice sheet. recent changes in the greenland ice sheet have received a great deal of attention in the scientific literature, as well as in the popular press, but estimating the net change in the mass of ice locked into the ice sheet is very difficult. much of the ice sheet is at high elevations, where temperatures remain below zero throughout the year, so with regional temperatures increasing (cappelen 2004) it is estimated that the accumulation here has increased in recent decades (box et al. 2006). however, at lower elevations there is evidence of greater ablation, which has been observed by airborne laser altimeters (krabill et al. 2000). the greater ablation is resulting in more water on the surface of the ice sheet during summer and greater run-off (hanna et al. 2008). overall, this pattern of change is thought to produce a negligible trend in the total surface mass balance of the ice sheet (box et al. 2006), but as the ice sheet rests on rock, the additional run-off will directly contribute to the rise in sea level. how much greenland is contributing to sea-level rise is difficult to estimate. the sea level is rising as a result of both thermal expansion and the melting of glacier ice, with both sources contributing about half each to the observed rise. for the period 1961–2003 the observed contribution resulting from thermal expansion was 0.42 mm per year, with total glacier melt (ice sheets, ice caps and small glaciers) adding 0.69 mm per year (solomon et al. 2007). in recent years the rise in sea level has accelerated, and over 1993–2003 the contribution from these two sources increased to 1.60 mm per year and 1.19 mm per year, respectively (solomon et al. 2007). estimates vary slightly over how much greenland is contributing to the current rise in sea level, but best estimates are that it accounts for 20–30% of the total sea-level rise (meier et al. 2007). the antarctic ice sheet. as discussed earlier, outside of the antarctic peninsula temperature changes across the continent have been rather small over the last 50 years, and since about 1980 there has even been a small cooling along the coast of east antarctica. not surprisingly, when coupled with the low temperatures that are experienced on the antarctic plateau, there is little evidence for melting of the ice sheet across most of the continent. analysis of the available accumulation data also suggests that there has not been any significant change in snowfall across the continent over the last 50 years (monaghan et al. 2006). however, two areas have exhibited marked change in recent decades. the rise in temperature across the antarctic peninsula has resulted in the disintegration of a number of floating ice shelves, including the larsen-b ice shelf in 2002, when 3250 km2 of shelf ice on the eastern side of the peninsula disintegrated into many small fragments over a period of months, releasing 500 billion tonnes of ice into the southern ocean. of course, this ice was already floating, so there was no impact on sea level. however, a recent study of the glaciers around the coast of the peninsula has shown that over the last 50 years 87% of the 244 glaciers studied had retreated, and that the average retreat rates have accelerated (cook et al. 2005). the second major area where change has been observed is in the pine island and thwaites glacier region of west antarctica. the pine island glacier is an extremely important part of the west antarctic ice sheet, as it discharges 75 giga tonnes per year of ice into the southern ocean, which is the largest discharge of any ice stream in west antarctica. satellite altimeter measurements have shown a major thinning of the ice sheet in the pine island region (davis et al. 2005), with satellite radar interferometry data showing that the grounding line retreated 5 km inland between 1992 and 1996 (rignot 1998). a recent analysis (rignot et al. 2008) using interferometry data found that ice sheet losses from coastal west antarctica had increased by 59% in the 10 years to 2006. atmospheric temperatures in the amundsen sea embayment rarely reach melting point, and it is very unlikely that changes in atmospheric conditions have directly played a role in the loss of ice. rather, it is most likely that a change in ocean circulation is responsible for the loss of ice, with relatively warm circumpolar deep water (cdw) on the continental shelf playing a role (thoma et al. 2008). however, changes in atmospheric circulation related to the movement of the amundsen sea low may have indirectly contributed to the variability in the delivery of cdw to the pine island area. melt in this area is thought to be responsible for most of the antarctic contribution to recent sea-level rise, which accounts for 10–20% of the total rise. attribution of the observed changes formal attribution of ongoing changes in the arctic is difficult because natural variability is large. however, evidence of an anthropogenic influence is emerging (gillett climate change in the two polar regions j. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd158 et al. 2009). analysis of model simulations provided to the ipcc shows that the inclusion of increasing greenhouse gases is essential to realistically represent the observed arctic temperature increases during recent decades. this contrasts with the warm period during the 1930s that wang et al. (2007) argue was caused by internal climate variability. other evidence consists of multiple indicators, including increased temperatures, diminished sea ice, degraded permafrost, enlarged melt area on greenland, increased water vapour, decreased snow extent, increased river discharge and the resulting ecosystem impacts. it is difficult to attribute a single event, such as the record minimum extent of arctic sea ice in september 2007, to anthropogenic climate change. however, there are several lines of evidence that support this conclusion. the 2007 ice loss greatly exceeded that in any other year in the observational record. control runs of global climate models with no anthropogenic forcing do not exhibit similar events, but large year-on-year decreases are simulated in some ensemble members with anthropogenic forcing. in the antarctic, the strengthening of the westerly winds that has taken place as a result of the shift of the sam into its positive phase is consistent with the simulated response to external forcing from stratospheric ozone depletion and greenhouse gas increases. it has also been shown that the resultant warming on the eastern side of the antarctic peninsula and the break-up of several ice shelves can be attributed, at least in part, to anthropogenic influence. there is also increasing evidence that the broadscale warming of the southern ocean is a result of anthropogenic forcing, combined with natural variability (levitus et al. 2005). prospects for the next century although the two polar regions have shown many contrasting features of change over recent decades, our best estimates are that by the end of the 21st century the similarities of change will be greater than the differences. producing reliable predictions of how the antarctic climate will evolve over the next century is not easy, especially as many models have great difficulty in reproducing recent changes. for example, monaghan, bromwich & schneider (2008) found that a representative sample of ipcc models predicted the antarctic to be warming at the global rate, whereas the rate of warming is much lower in reality. nevertheless, the ipcc models do provide useful, broad guidance on how the climate will change in the future, although it is not possible to put much weight on regional detail. bracegirdle et al. (2008) used the ipcc predictions to examine how a number of aspects of the antarctic climate system may change in the future. they found that temperatures across the antarctic were expected to increase by about 0.33 � 0.1°c per decade on land and 0.26 � 0.1°c per decade in the ocean/sea-ice zone, which is approximately the same change as the mean change for the land areas of the earth. where sea ice is lost around east antarctica the warming is predicted to be about 0.5°c per decade. larger increases in annual mean temperature are expected across the arctic, with values of 0.6–0.8°c per decade over the northern parts of the continents, and the largest values of 1°c per decade over the arctic ocean (solomon et al. 2007). however, it appears that the real world is on a faster trajectory of arctic sea-ice loss than the expected value projected by ipcc models, so great care must be exercised in using model output. it is thus important to understand that although many of the ipcc projections are based on averages of model runs, reality is but a single realization. as arctic sea-ice extent is declining faster than forecast by climate models, a goal has to be to develop a framework for describing climate model uncertainty in sea-ice retreat. the ipcc’s fourth assessment report models have a very wide range of projections for sea-ice evolution over the next century, and a major target must be to reduce this uncertainty. there has been a great deal of discussion about if and when the arctic ocean will become ice-free in the summer during the present century. if the changes seen in recent years are indicative of what will happen in the future, there could be a nearly ice-free summer arctic before 2030, as suggested by stroeve et al. (2008). it should be noted that some scientists feel that even this date is too conservative. with such large changes in arctic sea-ice extent in recent years it is interesting to consider whether there are any possible brakes on the system. polar amplification of global warming may slow the poleward transport of sensible heat, but the transport of latent heat may increase. arctic cloud cover is increasing during winter, and decreasing during other seasons. however, over the arctic ocean the “shading effect” will be small because of the low contrast between clouds and ice/snow. increased precipitation–evaporation may slow the thermohaline circulation, but model results imply a constant or even increasing flow of warm aw into the arctic ocean. in the south, the recent increase in antarctic sea-ice extent is expected to peak within the next decade or two as greenhouse gas levels rise and stratospheric ozone levels recover. by the end of the century there is expected to be a reduction in the antarctic sea-ice area of about 33%, over the year as a whole, and a 25% reduction of sea-ice extent (bracegirdle et al. 2008). climate change in the two polar regionsj. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 159 in the antarctic, the future recovery of stratospheric ozone concentrations will weaken the positive trend in the sam index, and will provide less of a mask to greenhouse gas impacts on warming across the continent and the sea-ice zone, thereby promoting sea-ice loss (perlwitz et al. 2008). a continued increase in greenhouse gases, however, has two effects: it contributes to maintaining the positive trend in the sam index, and also augments the surface energy balance. which effect will dominate the coming decades is a question of ongoing research (keeley et al. 2007). the states of the arctic and antarctic climate systems are the result of complex interactions between external forcing, large-scale nonlinear climate dynamics and regional feedbacks. however, given the recent dramatic loss of multiyear sea ice in the north, and the projections of continued global warming, it seems nearly impossible for summer arctic sea ice to return to its climatological extent of prior to 1980. over the next century models suggest an increase of snowfall across the antarctic of 25–50%, with a switch of 10% of snowfall to rain in summer. the winter warming of the antarctic peninsula is expected to continue as a result of reduced sea-ice extent, and similar warming will spread to many other coastal regions. a widespread increase of the circumpolar westerlies is expected, leading to a decrease of coastal easterlies, particularly in summer and autumn. the models suggest westerlies over the southern ocean will increase by 10–20%, but it is not expected that there will be large changes in winds over the continent. however, most of antarctica will remain well below freezing, so there will be no largescale melting of the ice sheet. however, a major uncertainty is what will happen in the amundsen sea sector of the west antarctic ice sheet. recent observations have shown that this is currently the most rapidly changing region of the entire antarctic ice sheet, with an acceleration of flow caused by the basal melting of its ice shelf and subsequent grounding line retreat of pine island glacier. the fear is that continued melting in this sector will result in the enhanced flow of ice from the interior of the ice sheet. conclusions the two polar regions have experienced markedly different climatic changes in recent decades, at a time when they were subject to near identical solar forcing and increases in greenhouse gas levels. initially, this may seem to suggest a paradox, but they are largely consistent with the known oceanic and atmospheric dynamics acting on contrasting topography, land/sea distribution and regional environmental factors. the recent changes at both poles, although different, are consistent with known impacts from shifts in atmospheric circulation and from thermodynamic processes that are, in turn, a consequence of anthropogenic influences on the climate system. changes in the annular modes have played an important role in the decadal variability for both polar regions. the sam has been important in driving many of the climatic changes observed across the antarctic and southern ocean, such as the increase in westerly winds and isolating the interior of the continent. the sam has shifted into its positive phase over recent decades, as a result of the ozone hole, increasing greenhouse gases and natural factors, such as volcanic aerosols, but the ozone hole has been the most important factor, and it is now known to be responsible for the warming on the eastern side of the antarctic peninsula. in the north, the nam was responsible for much of the flushing of sea ice from the arctic ocean in the 1990s, which helped to precondition the region for the large losses of sea ice in the first decade of the 21st century. however, the link between the nam and sea-ice extent now seems to be broken, suggesting that other factors have played the largest part in the recent ice minima. to better understand the climate changes that have taken place over recent decades, and to produce improved projections for the next century, we need better coupled atmosphere–ocean–cryosphere models. yet the polar climate systems involve complex interactions between the different parts of the system, and there are numerous feedbacks (e.g., ice albedo and aerosol– radiation–circulation). incorporating such processes into the models is a major challenge, but this must be achieved if we are to understand how the environments of the polar regions will evolve in the future, under increasing levels of greenhouse gas emission. the fact that climate models are generally too slow in replicating the recent large losses of ice is a worrying factor in our attempts to simulate the arctic climate system. in recent years we have seen some remarkable changes in both polar regions. our understanding of the mechanisms behind these events is improving; however, the complex interactions between the atmosphere, ocean and cryosphere are difficult to unravel, and even more difficult to model. the future, no doubt, holds more surprises, and it is essential that we obtain greater predictive capability in order to understand what will happen in these two climatically critical regions. changes are occurring faster than was anticipated, even a few years ago. we need to proceed with dispatch in using all observational and modelling tools to promote the understanding of the further potential for high-latitude impacts. climate change in the two polar regions j. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd160 acknowledgements this paper draws on the discussions at the recent high latitude climate change workshop, held at the pacific marine environment laboratory (pmel), seattle, wa, in october 2007. we are grateful to the scientists who participated and the management of pmel for hosting the meeting. we would also like to thank the scientific committee on antarctic research, the international arctic science council, the climate and cryosphere project of the world climate research programme, the international commission on polar meteorology and the noaa arctic program for supporting the workshop. references abdul a.o. & burn d.h. 2006. trends and variability in the hydrological regime of the mackenzie river basin. journal of hydrology 319, 282–294. aoki s. 2002. coherent sea level response to the antarctic oscillation. geophysical research letters 29, article no. 1950, doi: 10.1029/2002gl015733. arblaster j. & meehl g.a. 2006. contributions of external forcings to southern annular mode trends. journal of climate 19, 2896–2905. baldwin m.p. 2001. annular modes in global daily surface pressure. geophysical research letters 28, 4115–4118. box j.e., bromwich d.h., veenhuis b.a., bai l.s., stroeve j.c., rogers j.c., steffen k., haran t. & wang s.h. 2006. greenland ice sheet surface mass balance variability (1988–2004) from calibrated polar mm5 output. journal of climate 19, 2783–2800. bracegirdle t.j., connolley w.m. & turner j. 2008. antarctic climate change over the twenty first century. journal of geophysical research—atmospheres 113, d03103, doi: 10.1029/2007jd008933. cappelen j. 2004. yearly mean temperature for selected meteorological stations in denmark, the faroe islands and greenland: 1873–2003. technical report 04–07. copenhagen: danish meteorological institute. chapman w.l. & walsh j.e. 2007. a synthesis of antarctic temperatures. journal of climate 20, 4096–4117. comiso j.c. & nishio f. 2007. trends in the sea ice cover using enhanced and compatible amsr-e, ssm/i and smmr data. journal of geophysical research—oceans 113, c02s07, doi: 10.1029/2007jc004257. cook a.j., fox a.j., vaughan d.g. & ferrigno j.g. 2005. retreating glacier fronts on the antarctic peninsula over the past half-century. science 308, 541–544. davis c.h., li y.h., mcconnell j.r., frey m.m. & hanna e. 2005. snowfall-driven growth in east antarctic ice sheet mitigates recent sea-level rise. science 308, 1898–1901. déry s.j., stieglitz m., mckenna e.c. & wood e.f. 2005. characteristics and trends of river discharge into hudson, james, and ungava bays, 1964–2000. journal of climate 18, 2540–2557. dickson r.r., meincke j., malmberg s.-a. & lee a.j. 1988. the ″great salinity anomaly″ in the northern north atlantic 1968–1982. progress in oceanography 20, 103–151. farman j.c., gardiner b.g. & shanklin j.d. 1985. large losses of total ozone in antarctica reveal seasonal cclox/ nox interaction. nature 315, 207–210. fetterer f., knowles k., meier w. & savoie m. 2002, updated 2009. sea ice index, 16 october 2007. boulder, co: national snow and ice data center. digital media. available at http://nsidc.org/news/press/2007_ seaiceminimum/images/20071017_extent.png. fogt r.l. & bromwich d.h. 2006. decadal variability of the enso teleconnection to the high latitude south pacific governed by coupling with the southern annular mode. journal of climate 19, 979–997. fyfe j.c. 2006. southern ocean warming due to human influence. geophysics research letters 33, l19701, doi: 10.1029/2006gl027247. fyfe j.c., boer g.j. & flato g.m. 1999. the arctic and antarctic oscillations and their projected changes under global warming. geophysics research letters 26, 1601–1604. fyfe j.c. & saenko o.a. 2006. simulated changes in the extratropical southern hemisphere winds and currents. geophysics research letters 33, l06701, doi: 10.1029/ 2005gl025332. gascard j.c., festy j., le gogg h., weber m., bruemmer b., offermann m., doble m., wadhams p., forsberg r., hanson s., skourup h., gerland s., nicolaus m., metaxin j.-p., grangeon j., haapala j., rinn e., haas c., heygster g., jakobson e., palo t., wilkinson j., kaleschke l., claffey k. j., elder b. & bottenheim j. 2008. exploring arctic transpolar drift during dramatic sea ice retreat. eos, transactions of the american geophysical union 89, 21–28. gille s.t. 2002. warming of the southern ocean since the 1950s. science 295, 1275–1277. gille s.t. 2003. float observations of the southern ocean. part 1. estimating mean fields, bottom velocities and topographic steering. journal of physical oceanography 33, 1167–1181. gille s.t. 2008. decadal-scale temperature trends in the southern hemisphere ocean. journal of climate 21, 4749–4765. gillett n.p., stone d.a., stott p.a., nozawa t., karpechko a.y., hegerl g.c., wehner m.f. & jones p.d. 2009. attribution of polar warming to human influence. nature geoscience 1, 760–764. gillet n.p. & thompson d.w.j. 2003. simulation of recent southern hemisphere climate change. science 302, 273–275. hall a. & visbeck m. 2002. synchronous variability in the southern hemisphere atmosphere, sea ice, and ocean resulting from the annular mode. journal of climate 15, 3043–3057. hanna e., huybrechts p., steffen k., cappelen j., huff r., shuman c., irvine-fynn t., wise s. & griffiths m. 2008. increased run-off from melt from the greenland ice sheet: a response to global warming. journal of climate 21(2), 331–341. climate change in the two polar regionsj. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 161 http://nsidc.org/news/press/2007_ helsen m.m., van den broeke m.r., van de wal r.s.w., van de berg w.j., van meijgaard e., davis c.h., li y.h. & goodwin i. 2008. elevation changes in antarctica mainly determined by accumulation variability. science 320, 1626–1629. hoerling m.p., hurrell j.w. & xu t. 2001. tropical origins for recent north atlantic climate change. science 292, 90–92. hoerling m.p., hurrell j.w., xu t., bates g.t. & phillips a.s. 2004. twentieth century north atlantic climate change. part ii. understanding the effect of indian ocean warming. climate dynamics 23, 23 391–23 405. hogg a.m., meredith m.p., blundell j.r. & wilson c. 2008. eddy heat flux in the southern ocean: response to variable wind forcing. journal of climate 21, 608–620. hughes c.w., woodworth p.l., meredith m.p., stepanov v., whitworth t. & pyne a.r. 2003. coherence of antarctic sea levels, southern hemisphere annular mode, and flow through drake passage. geophysical research letters 30, article no. 1464, doi: 10.1029/2003gl017240. jacobs s.s., giulivi c.f. & mele p.a. 2002. freshening of the ross sea during the late 20th century. science 297, 386–389. johannessen o.m., bengtsson l., miles m.w., kuzmina s.i., semenov v.a., alekseev g.v., nagurnyi a.p., zakharov v.f., bobylev l.p., pettersson l.h., hasselmann k. & cattle h.p. 2004. arctic climate change: observed and modelled temperature and sea-ice variability (vol. 56a, p. 328, 2004). tellus series a—dynamic meteorology and oceanography 56, 328–341. johanson c.m. & fu q. 2007. antarctic atmospheric temperature trend patterns from satellite observations. geophysics research letters 34, l12703, doi: 10.1029/ 2006gl029108. jones j.m. & widmann m. 2003. instrumentand tree-ring-based estimates of the antarctic oscillation. journal of climate 16, 3511–3524. keeley s.p.e., gillett n.p., thompson d.w.j., solomon s. & forster p.m. 2007. is antarctic climate most sensitive to ozone depletion in the middle or lower stratosphere? geophysics research letters 34, l22812, doi: 10.1029/ 2007gl031238. kidson j.w. 1999. principal modes of southern hemisphere low-frequency variability obtained from ncep-ncar reanalyses. journal of climate 12, 2808–2830. king j.c. 1994. recent climate variability in the vicinity of the antarctic peninsula. international journal of climatology 14, 357–369. krabill w., abdalati w., frederick e., manizade s., martin c., sonntag j., swift r., thomas r., wright w. & yungel j. 2000. greenland ice sheet: high-elevation balance and peripheral thinning. science 289, 428–430. kushner p.j., held i.m. & delworth t.l. 2001. southern hemisphere atmospheric circulation response to global warming. journal of climate 14, 2238–2249. le quéré c., rodenbeck c., buitenhuis e.t., conway t.j., langenfelds r., gomez a., labuschagne c., ramonet t., nakazawa t., metzl n., gillett n.p. & heimann m. 2007. saturation of the southern ocean co2 sink due to recent climate change. science 316, 1735–1738. levitus s., antonov j. & boyer t. 2005. warming of the world ocean, 1955–2003. geophysics research letters 32, l02604, doi: 10.1029/2004gl021592. marshall g.j. 2003. trends in the southern annular mode from observations and reanalyses. journal of climate 16, 4134–4143. marshall g.j., orr a., van lipzig n.p.m. & king j.c. 2006. the impact of a changing southern hemisphere annular mode on antarctic peninsula summer temperatures. journal of climate 19, 5388–5404. marshall g.j., stott p.a., turner j., connolley w.m., king j.c. & lachlan-cope t.a. 2004. causes of exceptional atmospheric circulation changes in the southern hemisphere. geophysics research letters 31, l14205, doi: 10.1029/2004gl019952. mayewski p.a. & maasch k.a. 2006. recent warming inconsistent with natural association between temperature and atmospheric circulation over the last 2000 years. climate of the past discussions 2, 327–355. meier m.f., dyurgerov m.b., rick u.k., o’neel s., pfeffer w.t., anderson r.s., anderson s.p. & glazovsky a.f. 2007. glaciers dominate eustatic sea-level rise in the 21st century. science 317, 1064–1067. meredith m.p. & hogg a.m. 2006. circumpolar response of southern ocean eddy activity to a change in the southern annular mode. geophysics research letters 33, l16608, doi: 10.1029/2006gl026499. meredith m.p. & king j.c. 2005. climate change in the ocean to the west of the antarctic peninsula during the second half of the 20th century. geophysics research letters 32, l19606, doi: 10.1029/2005gl024042. meredith m.p., woodworth p.l., hughes c.w. & stepanov v. 2004. changes in the ocean transport through drake passage during the 1980s and 1990s, forced by changes in the southern annular mode. geophysics research letters 31, l21305, doi: 10.1029/2004gl021169. min s.k., zhang x.b. & zwiers f. 2008. human-induced arctic moistening. science 320, 518–520. monaghan a.j. & bromwich d.h. 2008. advances in describing recent antarctic climate variablity. bulletin of the american meteorological society 89, 1295–1306. monaghan a.j., bromwich d.h., chapman w.l. & comiso j.c. 2008. recent variability and trends of antarctic near-surface temperature. journal of geophysical research 113, d04105, doi: 10.1029/2007jd009094. monaghan a.j., bromwich d.h., fogt r.l., wang s.-h., mayewski p.a., dixon d.a., ekaykin a., frezzotti m., goodwin i., isaksson e., kaspari s.d., morgan v.i., oerter h., van ommen t.d., van der veen c.j. & wen j. 2006. insignificant change in antarctic snowfall since the international geophysical year. science 313, 827–831. monaghan a.j., bromwich d.h. & schneider d.p. 2008. twentieth century antarctic air temperature and snowfall climate change in the two polar regions j. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd162 simulations by ipcc climate models. geophysics research letters 35, l07502, doi: 10.1029/2007gl032630. morison j.h., aagaard k., falkner k.k., hatakeyama k., moritz r., overland j.e., perovich d.k., shimada k., steele m., takizawa t. & woodgate r. 2002. north pole environmental observatory delivers early results. eos, transactions of the american geophysical union 83, 357–361. nghiem s.v., rigor i.g., perovich d.k., clemente-colon p., weatherly j.w. & neumann g. 2007. rapid reduction of arctic perennial sea ice. geophysics research letters 34, l19504, doi: 10.1029/2007gl031138. oke p.r. & england m.h. 2004. oceanic response to changes in the latitude of the southern hemisphere subpolar westerly winds. journal of climate 17, 1040–1054. overland j.e., spillane m.c., percival d.b., wang m. & mofjeld h.o. 2004. seasonal and regional variation of pan-arctic surface air temperature over the instrumental record. journal of climate 17, 23 263–23 282. overland j.e., wang m. & salo s. 2008. the recent arctic warm period. tellus series a—dynamic meteorology and oceanography 60, 589–597. perlwitz j., pawson s., fogt r.l., nielsen j.e. & neff w.d. 2008. impact of stratospheric ozone hole recovery on antarctic climate. geophysics research letters 35, l08714, doi: 10.1029/2008gl033317. peterson b.j., holmes r.m., mcclelland j.w., vorosmarty c.j., lammers r.b., shiklomanov a.i., shiklomanov i.a. & rahmstorf s. 2008. increasing river discharge to the arctic ocean. science 298, 2171–2173. pezza a.b., durrant t., simmonds i. & smith i. 2008. southern hemisphere synoptic behavior in extreme phases of sam, enso, sea ice extent and southern australia rainfall. journal of climate 21, 5566–5584. quadrelli r. & wallace j.m. 2002. dependence of the structure of the northern hemisphere annular mode on the polarity of enso. geophysical research letters 29, 2132–2135. randel w.j. & wu f. 1999. cooling of the arctic and antarctic polar stratospheres due to ozone depletion. journal of climate 12, 1467–1479. rignot e.j. 1998. fast recession of a west antarctic glacier. science 281, 549–551. rignot e., bamber j.l., van den broeke m.r., davis c., li y.h., van de berg w.j. & van meijgaard e. 2008. recent antarctic ice mass loss from radar interferometry and regional climate modelling. nature geoscience 1, 106–110. rintoul s.r. 2007. rapid freshening of antarctic bottom water formed in the indian and pacific oceans. geophysics research letters 34, l06606, doi: 10.1029/2006gl028550. schweiger a., zhang j., lindsay r.w. & steele m. 2008. did unusually sunny skies help drive the record sea ice minimum? geophysics research letters 35, l10503, doi: 10.1029/2008gl033463. serreze m.c., walsh j.e., chapin f.s., osterkamp t., dyurgerov m., romanovsky v.e., oechel w., morison j. & barry r.g. 2000. observational evidence of recent change in the northern high-latitude environment. climate change 46, 159–207. sexton d.m.h. 2001. the effect of stratospheric ozone depletion on the phase of the antarctic oscillation. geophysics research letters 28, 3697–3700. shimada k., komashida t., itoh m., nishino s., carmack e., mclaughlin f.a., zimmermann s. & proshutinsky a. 2006. pacific ocean inflow: influence on catastrophic reduction of sea ice cover in the arctic ocean. geophysics research letters 33, l08605, doi: 10.1029/2005gl025624. simmonds i. 2003. modes of atmospheric variability over the southern ocean. journal of geophysical research—oceans 108, article no. 8078, doi: 10.1029/2000jc000542. simmonds i., burke c. & keay k. 2008. arctic climate change as manifest in cyclone behavior. journal of climate 21, 5777–5796. simmonds i. & jacka t.h. 1995. relationships between the interannual variability of antarctic sea ice and the southern oscillation. journal of climate 8, 637–647. solomon s., qin d., manning m., chen z., marquis m., averyt k.b., tignor m. & miller h.l. jr. (eds.) 2007. climate change 2007. the physical science basis. contribution of working group i to the fourth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. stammerjohn s.e., martinson d.g., smith r.c. & iannuzzi r.a. 2008. sea ice in the western antarctic peninsula region: spatio-temporal variability from ecological and climate change perspectives. deep-sea research part ii 55, 2041–2058. stammerjohn s.e., martinson d.g., smith r.c., yuan x. & rind d. 2008. trends in antarctic annual sea ice retreat and advance and their relation to el niño–southern oscillation and southern annular mode variability. journal of geophysical research—oceans 113, c03s90, doi: 10.1029/2007jc004269. steele m. & boyd t. 1998. retreat of the cold halocline layer in the arctic ocean. journal of geophysical research—oceans 103, 10 419–10 435. steele m., ermold w. & zhang j. 2008. arctic ocean surface warming trends over the past 100 years. geophysics research letters 35, l02614, doi: 10.1029/2007gl031651. steig e.j., schneider d.p., rutherford s.d., mann m.e., comiso j.c. & shindell d.t. 2009. warming of the antarctic ice-sheet surface since the 1957 international geophysical year. nature 457, 459–462. stone d.a., weaver a.j. & stouffer r.j. 2001. projection of climate change onto modes of atmospheric variability. journal of climate 14, 3551–3565. stroeve j., holland m.m., meier w., scambos t. & serreze m.c. 2007. arctic sea ice decline: faster than forecast. geophysics research letters 34, l09501, doi: 10.1029/ 2007gl029703. stroeve j., serreze m.c., drobot s., gearheard s., holland m., maslanik j., meier w. & scambos t. 2008. arctic sea ice extent plummets in 2007. eos, transactions of the american geophysical union 89, 13. thoma m., jenkins a., holland d. & jacobs s. 2008. modelling circumpolar deep water intrusions on the climate change in the two polar regionsj. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd 163 amundsen sea continental shelf, antarctica. geophysical research letters 35, l18602, doi: 10.1029/2008gl034939. thomas e.r., marshall g.j. & mcconnell j.r. 2008. a doubling in snow accumulation in the western antarctic peninsula since 1850. geophysics research letters 35, l01706, doi: 10.1029/2007gl032529. thompson d.w.j. & solomon s. 2002. interpretation of recent southern hemisphere climate change. science 296, 895–899. thompson d.w.j. & wallace j.m. 2000. annular modes in the extratropical circulation. part i. month-to-month variability. journal of climate 13, 1000–1016. turner j. 2004. the el niño–southern oscillation and antarctica. international journal of climatology 24, 1–31. turner j., colwell s.r., marshall g.j., lachlan-cope t.a., carleton a.m., jones p.d., lagun v., reid p.a. & iagovkina s. 2005. antarctic climate change during the last 50 years. international journal of climatology 25, 279–294. turner j., comiso j.c., marshall g.j., lachlan-cope t.a., bracegirdle t.j., maksym t., meredith m.p., wang z. & orr a. 2009. non-annular atmospheric circulation change induced by stratospheric ozone depletion and its role in the recent increase of antarctic sea ice extent. geophysics research letters 36, l08502, doi: 10.1029/2009gl037524. turner j., lachlan-cope t.a., colwell s.r., marshall g.j. & connolley w.m. 2006. significant warming of the antarctic winter troposphere. science 311, 1914–1917. van den broeke m.r. & van lipzig n.p.m. 2004. changes in antarctic temperature, wind, and precipitation in response to the antarctic oscillation. annals of glaciology 39, 119–126. volodin e.m. & galin v.y. 1999. interpretation of winter warming on northern hemisphere continents in 1977–94. journal of climate 12, 2947–2955. walker d.p., brandon m.a., jenkins a., allen j.t., dowdeswell j.a. & evans j. 2007. oceanic heat transport onto the amundsen sea shelf through a submarine glacial trough. geophysics research letters 34, l02602, doi: 10.1029/ 2006gl028154. wang m., overland j.e., kattsov v., walsh j.e., zhang x. & pavlova t. 2007. intrinsic versus forced variation in coupled climate model simulations over the arctic during the 20th century. journal of climate 20, 1093–1107. yuan x. 2004. enso-related impacts on antarctic sea ice: a synthesis of phenomenon and mechanisms. antarctic science 16, 415–425. yuan x. & li c. 2008. climate modes in southern high latitudes and their impacts on antarctic sea ice. journal of geophysical research—oceans 113, c06s91, doi: 10.1029/ 2006jc004067. yuan x.j. & martinson d.g. 2000. antarctic sea ice extent variability and its global connectivity. journal of climate 13, 1697–1717. zhang y., wallace j.m. & battisti d.s. 1997. enso-like interdecadal variability: 1900–93. journal of climate 10, 1004–1020. zhu x.j., sun j.l.k., liu z.y., liu q.y. & martin j.e. 2007. a synoptic analysis of the interannual variability of winter cyclone activity in the aleutian low region. journal of climate 20, 1523–1538. climate change in the two polar regions j. turner & j. overland polar research 28 2009 146–164 © 2009 the authors, journal compilation © 2009 blackwell publishing ltd164 doi:10.3402/polar.v33.21624 r e s e a r c h / r e v i e w a r t i c l e deterrent activities in the crude lipophilic fractions of antarctic benthic organisms: chemical defences against keystone predators laura núñez-pons & conxita avila department of animal biology (invertebrates) & biodiversity research institute, faculty of biology, university of barcelona, av. diagonal 643, es-08028 barcelona, catalonia, spain keywords antarctic invertebrates; antarctic algae; chemical ecology; sea star odontaster validus; amphipod cheirimedon femoratus; chemical defence. correspondence laura núñez-pons, department of animal biology (invertebrates) & biodiversity research institute, faculty of biology, university of barcelona, av. diagonal 643, es-08028 barcelona, catalonia, spain. e-mail: lauguau@gmail.com abstract generalist predation constitutes a driving force for the evolution of chemical defences. in the antarctic benthos, asteroids and omnivore amphipods are keystone opportunistic predators. sessile organisms are therefore expected to develop defensive mechanisms mainly against such consumers. however, the different habits characterizing each predator may promote variable responses in prey. feeding-deterrence experiments were performed with the circumpolar asteroid macropredator odontaster validus to evaluate the presence of defences within the apolar lipophilic fraction of antarctic invertebrates and macroalgae. a total of 51% of the extracts were repellent, yielding a proportion of 17 defended species out of the 31 assessed. these results are compared with a previous study in which the same fractions were offered to the abundant circum-antarctic amphipod cheirimedon femoratus. overall, less deterrence was reported towards asteroids (51%) than against amphipods (80.8%), principally in sponge and algal extracts. generalist amphipods, which establish casual host�prey sedentary associations with biosubstrata (preferentially sponges and macroalgae), may exert more localized predation pressure than sea stars on certain sessile prey, which would partly explain these results. the nutritional quality of prey may interact with feeding deterrents, whose production is presumed to be metabolically expensive. although optimal defence theory posits that chemical defences are managed and distributed as to guarantee protection at the lowest cost, we found that only a few organisms localized feeding deterrents towards most exposed and/or valuable body regions. lipophilic defensive metabolites are broadly produced in antarctic communities to deter opportunistic predators, although several species combine different defensive traits. predation constitutes an interaction in which an organism attacks another, resulting in its eventual digestion. in prey with clonal growth, predation normally occurs only on a part of the victim, rarely invoking death (heck & valentine 1995; sánchez et al. 2004). after sub-lethal attacks, this type of prey may respond with plastic anti-predatory behaviour, morphology or chemistry, or a combination (harvell 1984; vermeij 1994). one efficient weapon against predation is chemical defence. many natural substances that display allelochemical (signalling) roles have no known primary metabolic function. these are considered secondary metabolites and are presumably costly but essential for fitness. anti-feedant chemical defences have been described in marine organisms, such as phlorotannins and terpene alcohols in algae, alkaloids in poriferans and dithiocarbamates in hydrozoans, which decrease the vulnerability of susceptible prey to future attacks (cronin & hay 1996; lindquist 2002; thoms et al. 2007; toth et al. 2007). chemical defences are an investment, as organisms must divert energy otherwise assigned polar research 2014. # 2014 l. núñez-pons & c. avila. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 to growth or reproduction and its cost is compensated by greater survival potential (harvell 1990). several theories have been formulated to explain where energy is saved and the costs of chemical defence minimized. the optimality theory (ot) proposes the use of all-purpose defensive tactics against a variety of enemies (herms & mattson 1992). the optimal defence theory (odt) postulates that deterrent metabolites are directed to particular types of predator and that they work together with other defensive traits to assure survival. according to the odt, defensive chemicals are allocated to the most valuable or vulnerable tissues (rhoades & gates 1976). the mechanisms by which defensive metabolites promote predation avoidance are still unknown since many are not highly poisonous but instead seem to have an effect promoting bad taste (paul 1992; mcclintock & baker 2001). nutritional quality must also be taken into consideration since some repellents are more (or only) effective in low-quality foods. this is likely because nutrients may bind to deterrent molecules or compete with these for enzymes, masking the stimuli that elicit rejection (duffy & paul 1992; cruz-rivera & hay 2003). hence, highly nutritive potential prey likely require larger amounts of, or more potent, defences to avoid consumption, while prey items of lower nutrient content tend to develop weaker defensive systems. for this reason, there are also costs for consumers: because they may need energetically expensive detoxification mechanisms when ingesting chemically defended organisms, they often eat poor-quality foods made up of undefended organisms (hay et al. 1987; lindquist & hay 1995; cruz-rivera & hay 2003). by consuming small amounts of a variety of foods, predators may dilute the possible negative effects derived from ingesting defensive metabolites, while also accruing the nutritional benefits derived from a mixed diet (bernays et al. 1994; stachowicz et al. 2007; sotka et al. 2009). as generalist predators are more prevalent, defences tend to be developed against them as opposed to specialists (paul et al. 2007). antarctic sea floors are characterized by unpredictable food availability, driving most consumers to develop flexible opportunistic foraging strategies. there is a predominantly circumpolar distribution of many of the dominant benthic organisms including keystone macroinvertebrate predators, mainly asteroids (dayton et al. 1974; mcclintock 1994). populations of amphipods with diversified diets are found in extremely high densities in association with biosubstrata, which often represent their potential prey as well as their shelter (see de broyer et al. 2007 for a review). in this case, small sedentary consumers could constitute a potential threat, sometimes worse than larger wandering predators, such as echinoderms or fish (hay et al. 1987; mcclintock & baker 2001; toth et al. 2007). sea stars feed by extruding the cardiac stomach against their food items (sloan 1980; brusca & brusca 2003). hence, in antarctic waters, where sea stars are keystone predators (mcclintock 1994), odt would predict that defences would be concentrated primarily in the outermost body parts of prey. however, it should be noted that other effective consumers of smaller size, like small crustaceans, may promote different types of defence distribution, especially in prey with large body perforations (i.e., oscula), like hexactinellid sponges that may be attacked from the inside (peters et al. 2009). in antarctic marine organisms, measures to deter consumption have been well documented by research using sea stars as model consumers; however, postingestion repulsive reactions have been scarcely tested (for reviews see avila et al. 2008; mcclintock et al. 2010; taboada et al. 2012). the current study evaluates the palatability of antarctic benthic invertebrates and algae with respect to the sympatric asteroid predator, odontaster validus. our past research has focused on the ecological role of lipidic metabolites in southern ocean organisms, in part because known feeding deterrents in marine environments are mostly lipid-soluble (sotka et al. 2009). in this study, we sought to evaluate defensive strategies developed against a common consumer*o. validus*in antarctic waters by using the lipophilic fractions of selected organisms to determine the presence of apolar defences and the hypothetical within-body allocation of deterrents. the results are discussed and compared with previous experiments with another important predator, the amphipod cheirimedon femoratus. materials and methods field collection of antarctic benthic samples benthic invertebrates and algae were collected during four antarctic cruises: two in the eastern weddell sea on board the rv polarstern (ant xv/3 and ant xxi/2 cruises); a third one on board the rv bio hespérides around the south shetland islands (ecoquim-2 cruise); and the fourth at deception island (actiquim-1 campaign). sampling took place at a total of 24 stations between 0 and 1524 m depth by using bottom and agassiz trawls (agts) and an epibenthic sledge (es) and, at shallow sites, by scuba diving (sd). at collection, all invertebrate and macroalgal samples exhibited a healthy, fresh appearance; none of them showed signs of decomposition. specimens belonging to the same species and chemical defences towards antarctic keystone predators l. núñez-pons & c. avila 2 (page number not for citation purpose) citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 from the same collecting station were grouped as a single sample, representing the mean population of each site. fresh organisms were then photographed on deck, and a representative portion of each sample was fixed in 10% formalin solution for further taxonomical identification at the university of barcelona. the rest of the material was subsequently frozen at �208c and shipped back to our laboratory, where it was preserved until processed. processing of samples: dissections and chemical extraction procedures invertebrate samples with large enough volumes to allow dissection were divided into different body parts in order to determine the potential chemical defences present in these different parts. samples were dissected as follows: sponges were divided into internal/external and apical/ basal regions; pennatulacean cnidarians into poliparium/ axe/peduncule; and ascidians into external/internal parts. all whole and dissected invertebrate samples and algae were then chemically extracted with acetone using a pestle at room temperature. the resulting extract was fractioned in diethyl ether and afterwards in butanol, always evaporating the solvent in vacuo using a rotary evaporator. all steps were repeated three times, except for the butanol fractionation, which was done only once. at the end, we obtained a dry ether and a dry butanol fraction and an aqueous residue. the dry ether and butanol fractions were weighted and divided into the total dry weight of the corresponding sample, as follows: dw (total dry weight) �ee (ether extract)�be (butanol extract)�dr (dry extracted residue). this yielded extracts at the natural sample concentration: n �ee/dw (table 1). see núñez-pons et al. (2012) for detailed information regarding sample collection and extraction yields. feeding-deterrence bioassays with sea stars individuals of the antarctic asteroid odontaster validus, measuring between 6 and 10.5 cm diameter, were collected at different sites in port foster bay, deception island, south shetland islands, antarctica (628 59.369’ s, 608 33.424’ w), for feeding-repellence assays during the actiquim-1 (december�february 2008/09) and actiquim-2 (january 2010) cruises by sd from 3 to 15 m depth. once testing was over, the sea stars were returned to the sea. odontaster validus is a predator commonly used in feeding acceptability studies (for review see avila et al. 2008). this asteroid is readily available, and its feeding response lends itself quite well to laboratory bioassays. the collected sea stars were kept in large tanks of seawater at spain’s gabriel de castilla station on deception island and were deprived of food for 5 days. the methodology followed in the experiments is detailed elsewhere (avila et al. 2000; iken et al. 2002). in brief, the assays consisted of 10 replicates, each with a 2.5 l container filled with seawater and one sea star, which was presented with a shrimp feeding cube sufficiently small (5 �5 �5 mm; 13.0993.43 mg of dry mass) to be fully consumed by the asteroid. these tiny shrimp food items contained 12.4% protein, 9.1% carbohydrates and 1.5% lipids, and 17.8 kj g �1 in dry wt and 4.1 kj g �1 wet wt, according to the manufacturer’s nutritional information and the atwater factor system (atwater & benedict 1902). they were loaded either with lipophilic extracts from antarctic invertebrates and algae, applied at their respective natural concentration in the treatment test, or with solvent carrier alone (diethyl ether) in the control tests. in both cases, the solvent was left to totally evaporate under a flow hood. the factor to normalize tissue concentrations of each fraction (hereafter referred to as natural concentration) was calculated on a dryweight basis employing the total dry weight of each sample, as previously mentioned. dry weight was chosen, rather than volume or wet weight, because it eliminates the water content, which may entail notable deviations in aquatic porous samples (table 1). when the sea stars everted the cardiac stomach and bolted down whole food cubes, we could measure the ‘‘defence per shrimp cube.’’ after 24 h, the food items that had been eaten were noted, and feeding repellence was evaluated by applying fisher’s exact tests for each assay referred to the control run simultaneously (sokal & rohlf 1995; fig. 1). uneaten extract-treated shrimp pieces were preserved frozen for further extraction and analysis by thin layer chromatography to check for possible alterations in the extracts. no changes were observed. because ees are not hydrophilic and the water temperature was fairly cold (ca. �18c), little, if any, loss to the water column was expected. results a total of 31 species comprising 40 samples of antarctic sponges (eight), cnidarians (13), ascidians (eight), bryozoans (one), echinoderms (one), hemichordate pterobranchs (one) and macroalgae (eight) yielded 52 lipophilic extracts, which were tested in feeding acceptability assays against the antarctic macropredator sea star odontaster validus. the control assays revealed a minimum consumption rate of seven pieces of shrimp out of 10 in all tests. significant repellent activities towards o. validus were detected in 17 species out of the 31 assessed. of the 49 l. núñez-pons & c. avila chemical defences towards antarctic keystone predators citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 table 1 data from the antarctic benthic organisms analysed. the second column shows the natural concentration values (%) of diethyl ether extracts (ee) in each sample, obtained by dividing ee weight by the total dry weight. taxonomic group and species name a % nee in dry weight b location gear c depth (m) algae ochrophyta adenocystis utricularis (bory de saint-vincent) skottsberg 1907 5.87 snow is. sd 1.5 ascoseira mirabilis skottsberg 1907 2.79 livingston is. sd 0.7 desmarestia anceps montagne 1842 7.63 deception is. sd 7.5 desmarestia antarctica d moe & silva 1989 epiphyted by geminocarpus austrogeorgiae skottsberg, 1907 4.49 livingston is. sd 0.7 desmarestia menziesiie j. agardh 1848 1.35 deception is. agt 109.7e rhodophyta georgiella confluens (reisch) kylin 1956 0.97 livingston is. sd 0.7 gigartina skottsbergii setchell & gardner, 1936 0.25 deception is. sd 12 palmaria decipiens (reinsch) ricker 1987 0.66 deception is. sd 1.3 porifera demospongiae isodictya toxophila burton, 1932 api: 5.28; bas: 6.79 weddell sea bt 332.8 hexactinellida anoxycalyx (scolymastra) joubini topsent, 1916 (1) api: 1.29; bas: 0.73 weddell sea agt 175.2 anoxycalyx (scolymastra) joubini topsent, 1916 (2) ext: 2.60; int: 1.83 weddell sea bt 290.8 rossella fibulata schulze & kirkpatrick, 1910 ext: 1.19; int: 1.75 weddell sea bt 332.8 rossella nuda topsent, 1901 1.17 weddell sea bt 308.8 rossella vanhoffeni (schulze & kirkpatrick, 1910) api: 2.36; bas: 0.61 weddell sea es 882 rossella villosa burton, 1929 api: 1.05; bas: 0.99 weddell sea agt 288.0 rossella sp.1 carter, 1872 ext: 1.20; int: 1.08 weddell sea agt 288.0 cnidaria anthozoa alcyonium antarcticum wright & studer, 1889 1.97 weddell sea bt 337.2 alcyonium haddoni wright & studer, 1889 4.61 deception is. sd 9 alcyonium roseum van ofwegen, häussermann & försterra, 2007 3.21 weddell sea agt 416 primnoisis antarctica (studer, 1878) (1) 0.45 weddell sea bt 294.8 primnoisis antarctica (studer, 1878) (2) 0.58 weddell sea bt 294.8 thouarella laxa versluys, 1906 (1) 1.44 weddell sea bt 308.8 thouarella laxa versluys, 1906 (2) 1.27 weddell sea bt 290.8 thouarella laxa versluys, 1906 (3) 0.88 weddell sea bt 294.8 thouarella laxa versluys, 1906 (4) 1.44 deception is. agt 100.4 thouarella minuta zapata-guardiola & lópez-gonzález 2009 2.00 weddell sea bt 338 umbellula antarctica kükenthal and broch, 1911 pol: 11.59; ax: 1.08 weddell sea bt 338 hydrozoa staurotheca antarctica hartlaub, 1904 3.93 weddell sea bt 597.6 symplectoscyphus glacialis (haderholm 1904) 1.02 weddell sea agt 175.2 chordata (ascidiacea) aplidium falklandicum millar, 1960 4.20 weddell sea bt 332.8 aplidium fuegiense cunningham, 1871 7.71 weddell sea agt 228.4 aplidium meridianum (sluiter, 1906) 12.85 weddell sea bt 284.4 synoicum adareanum (b&w) (herdman, 1902) (1) ext: 2.00; int: 3.31 weddell sea bt 337.2 synoicum adareanum (b&w) (herdman, 1902) (2) api: 5.57; ext: 1.81; int: 2.73 weddell sea agt 288.0 synoicum adareanum (br) (herdman, 1902) 3.68 weddell sea agt 277.2 synoicum adareanum (o) (herdman, 1902) (1) 2.04 weddell sea agt 288.0 synoicum adareanum (o) (herdman, 1902) (2) ext: 2.80; int: 2.64 weddell sea bt 337.2 bryozoa isoschizoporella secunda hayward and taylor, 1984 0.75 weddell sea agt 277.2 echinodermata (holoturoidea) peniagone vignioni herouard, 1901 2.19 weddell sea agt 1524.8 hemichordata (pterobranchia) cephalodiscus nigrescens lankester, 1905 7.43 weddell sea bt 284.4 chemical defences towards antarctic keystone predators l. núñez-pons & c. avila 4 (page number not for citation purpose) citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 fractions tested, 25 indicated the presence of deterrents (51%). the remaining 14 species provided 24 extracts (49%) that were suitable for sea star consumption. in terms of groups, ascidians and cnidarians exhibited the highest activity with 83.3 and 61.5% of repellent extracts, respectively, followed by algae (25%) and sponges (23.1%; fig. 2). the only bryozoan tested, as well as the holoturian samples were also significantly repellent, whereas the hemichordate pterobranch yielded an inactive ether fraction. in the group of the ascidians, both synoicum adareanum (black and white morphotype [b&w]) samples 1 and 2 with internal fractions were rejected by o. validus, but their external lipophilic extracts were consumed (elicited no significant feeding deterrent activity). most seaweed and poriferan fractions were suitable for sea star consumption, except for two algal extracts from ascoseira mirabilis and georgiella confluens, and two sponge fractions from isodictya toxophyla and rossella nuda, which were rejected. finally, five cnidarian extracts, including those from the polyparium and axis body regions of umbellula antarctica, two from samples of the gorgonians primnoisis antarctica and thouarella laxa, and one from the hydrozoan staurotheca antarctica were accepted by the star (table 1; fig. 1). discussion feeding deterrence as means of defence against antarctic benthic predators the assays with the sea star odontaster validus demonstrated a widespread presence of lipid-soluble deterrents within cnidarians and ascidians. the opposite pattern is shown in sponges and algae. the low deterrence we found in sponges conflicts with other published findings. past studies, however, usually tested demosponge species, which are prolific sources of bioactive natural products and are presumably far better defended than the hexactinellids, which represent most of our porifera (mcclintock & baker 2001; avila et al. 2008; mcclintock et al. 2010; taboada et al. 2012). when comparing the current study with parallel work testing the same fractions against the omnivore lyssianasid amphipod cheirimedon femoratus (núñez-pons et al. 2012), we observed that out of the 49 lipophilic extracts assessed in both bioassays, 22 (44.9%) were deterrent and five (10.2%) were suitable for both predators. therefore, 55.1% (27 fractions) elicited the same response in the two predators. twenty-two fractions had different results for the two species, 19 (38.8%) being discouraging for the amphipod but palatable for o. validus, and the remaining three fractions were repellent just for the sea star. overall, there was a 32.7% higher incidence of deterrency towards amphipod feeding than against sea star ingestion, especially in the groups of sponges and algae (figs. 1, 2). even if o. validus and c. femoratus have both circumpolareurybathic distributions, and extensive generalist diets (scavenger, detritivore, planktivore; bregazzi 1972; mcclintock 1994; de broyer et al. 2007), the distinct ecological habits of these predators may promote variable defensive responses in potential prey. in general, sea stars are mobile macropredators that start extra-oral digestion from the surface of the victims (sloan 1980). amphipods instead feed with minute peripheral bites, and only prolonged feeding would allow access to internal tissues. however, in prey organisms with evident openings, these small crustaceans may reach the inner regions to forage (peters et al. 2009). we compare the results of the present study with those from núñez-pons et al. (2012), estimating prey protective adaptations against two different predators. methodological considerations and feeding deterrent activities the experiments with odontaster validus were no-choice feeding repellence tests, whereas those performed with cheirimedon femoratus by núñez-pons et al. (2012) were preference assays with-choice. when allowed to choose between extract-treated versus palatable control food pearls, predators may be better able to discriminate repellent agents. another difference in the two studies is that the diets were distinct in energetic content: alginate pearls used with the amphipod c. femoratus were less nutritious (19 kj g �1 dry wt and 1.5 kj g �1 wet wt) than the shrimp cubes presented to o. validus table 1 (continued ) taxonomic group and species namea % nee in dry weight b location gearc depth (m) a morphotypes are abbreviated as follows: black and white (b&w); brown (br); orange (o). bbody parts are abbreviated as follows: apical (api); basal (bas); external (ext); int: internal; poliparium (pol); axis (ax). c collecting gear is abbreviated as follows: bottom trawl (bt); agassiz trawl (agt); epibenthic sledge (es); scuba diving in shallow sites (sd). d desmarestia antarctica samples were second-year plants. efor d. menziesii, depth record is that given by the dredge collection station, but sample algal specimens probably come from shallower bottoms; material was in healthy condition. unlikely to have drifted to the site. l. núñez-pons & c. avila chemical defences towards antarctic keystone predators citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 (17.8 kj g �1 dry wt and 4.1 kj g �1 wet wt; by atwater factors; atwater & benedict 1902). therefore, some repellent extracts might have been less evident in the sea star tests due to a higher nutritional value of shrimp compared to alginate pearls (and potentially compared to some of the samples too). despite these modifications, we are still able to make comparative approximations related to deterrence potential since nutritious foods can interact with defensive metabolites and constrain the types or concentrations that might be efficacious in nature for discouraging predators. an idea of the potency of deterrents can be drawn by measuring their activity in the two kinds of experiments using assay foods of distinct energy content (duffy & paul 1992; cruz-rivera & hay 2003). most of the fractions deterrent to amphipods but accepted by sea stars came from less nutritious samples: hexactinellid sponges; and fibrous body parts: tunics of s. adareanum (b&w) and the stalk from u. antarctica. in these cases, moderate to poor chemical defence along with low nutritional value may operate in tandem to make these body parts less appealing. in general, the optimal assay foods are those energetically equivalent to the studied prey; however, o. validus would not feed on gelified diets (authors’ pers. obs.). this study tested only ether fractions, and possible defences exclusive to other fractions were not analysed. fig. 1 bar diagrams of the feeding repellence bioassays with the sea star odontaster validus for the four major groups assessed: (a) sponges, (b) cnidarians, (c) ascidians, (d) algae � minor groups (abbreviated as follows: bryozoa [bry], echinodermata [ech], hemichordata [hem]), showing the results of each paired test with control and extract-treated diets (ee), represented by the percentage of acceptance. asterisks indicate significant differences with the control as the preferred food (fisher’s exact test). the hexactinellid s. (a.) joubini sample 1 and the octocoral thouarella laxa sample 2 were not assayed in this experiment. at the top of each graph the results are compared (exact wilcoxon test) with findings from feeding preference bioassays in a parallel study with the amphipod cheirimedon femoratus (núñez-pons et al. 2012). chemical defences towards antarctic keystone predators l. núñez-pons & c. avila 6 (page number not for citation purpose) citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 macroalgae and sponges as potential prey or as potential host-and-prey lipophilic deterrence in algae was shown to be low towards sea stars and high towards amphipods. this could be due, in part, to a higher ingestion of algal material by c. femoratus ovigerous females and juveniles during summer (bregazzi 1972). hydrophilic deterrents (i.e., phlorotanins), often contributing to asteroid repellence in algae, could have been missed in our analysis (amsler et al. 2005). antarctic benthic amphipods generally associate with living substrata with no obligate relationships (de broyer et al. 2001), obtaining tri-dimensional habitat and food as well as chemical refuges from prospective enemies, like fish, when hosts are chemically defended (mcclintock et al. 2009; zamzow et al. 2010). cheirimedon femoratus may be found as deep as 1500 m (krapp et al. 2008). at deception island, it is both abundant and commonly found on macrophytes and poriferans (authors’ pers. obs.), similar to other northern cheirimedon amphipods (vader 1984). such a niche is filled in some antarctic areas by several other species (huang et al. 2007; amsler et al. 2009). organism associations adapt in diverse interactions depending on the chemical potential of the host and the feeding adaptations of the grazers. as part of its opportunistic habits, c. femoratus may graze on host tissues directly (authors’ pers. obs.), while also profiting from adhered detritus and diatoms (bregazzi 1972; graeve et al. 2001). this leads to a more constant localized pressure on hostand-prey organisms than that exerted by wandering macropredators (hay et al. 1987; toth et al. 2007), like o. validus, which forages on ubiquitous prey with less recurrent encounters (mcclintock 1987, 1994). our algae are comprised of antarctic brown and red seaweed, which are rich sources of food (11�13 kj g�1 dry wt; montgomery & gerking 1980; gomez & westermeier 1995) and bioactive molecules. except for one species, all sponges were hexactinellids with no reported secondary metabolites (blunt et al. 2013 and previous reports). their high spicule content and low energetic value (5�6 kj g�1 dry wt; mcclintock 1987; barthel 1995) are believed to discourage predators. average ether-lipophilic yields showed low values in hexactinellids (ca. 1.3%) and in rodophyta (0.6%), and higher ones (ca. 4.4%) in brown algae (table 1). the small ether fraction yield in red algae may reflect their small lipid content (montgomery & gerking 1980). antarctic poriferans and macroalgae hold high diversities of amphipods (kunzmann 1996; huang et al. 2007; amsler et al. 2009). moreover, some algae act as a chemical refuges, including desmarestia menziesii with lipophilic deterrents and d. anceps with hydrophilic defences; this might have been missed in our study, which only tested ether partitions. our inactive extract of d. menziesii from deeper waters (ca. 110 m) may have different chemistry due to the variation in depths or the extraction protocol, which yielded unexpected inactivity. other algae, like palmaria decipiens, are more preferred as food (though not for our amphipod) but are not preferred as hosts (amsler et al. 2005; aumack et al. 2010; bucolo et al. 2011). analogous chemical refuges have not been described in antarctic sponges, yet some defended species host dense amphipod populations (amsler et al. 2009). most of the seaweed and sponge fractions reflected no activity against o. validus, but were rejected by c. femoratus, which may use them as substrata and occasionally as prey. the few fractions that repelled both asteroids fig. 2 comparison of results from bioassays with the sea star odontaster validus and those with the amphipod cheirimedon femoratus from núñezpons et al. (2012) testing the incidence of repellent activities in diethyl ether extracts (ees) from the samples assessed, which included invertebrates and macroalgae. in (a), a horizontal bar diagram shows the total activity of all assessed extracts assessed, contrasting tests with asteroids and amphipods. in (b) coincident and non-coincident deterrent activities are shown for all the tested fractions, comparing the two experiments; plus signs indicate the presence of feeding repellents and minus signs indicate the lack of them. l. núñez-pons & c. avila chemical defences towards antarctic keystone predators citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 and amphipods were those from the macroalgae ascoseira mirabilis and georgiella confluens, the demosponge isodictya toxophila and the hexactinellid rossella nuda. rossella nuda is abundant and primarily foraged by spongivorous generalists, including o. validus. the richer fractions and repellent chemistry of i. toxophila supports the greater bioactivity of demosponges compared to glass sponges (mcclintock 1987; barthel 1995). extracts that showed palatability in this study and also towards c. femoratus in our previous study were those from the algae adenocystis utricularis and desmarestia antarctica (second-year) epiphyted by geminocarpus austrogeorgiae (table 1, fig. 1). amsler et al. (2005) proposed that in second-year d. antarctica mild acidity could assist weak hydrophilic repellents against sea stars, while in first-year algae the lipophilic extract was already effective, suggesting a loss of lipophilic defences with senescence. glass sponges are readily preyed upon by odontaster and acanthaster sea stars (mcclintock 1987), and as it turns out, no lipophilic repellents or external defence allocation were shown to assist these sponges in asteroid avoidance (furrow et al. 2003). instead, efficient defences towards amphipods were found distributed throughout the volcano-shaped rossellids. opportunistic amphipods, through lax associations, may influence the chemical ecology of macroalgae and sponges and change the expectations of the odt (rhoades & gates 1976), replacing, in some cases, asteroids as the main inducers of defence distribution. anti-predatory protection in other invertebrate groups antarctic cnidaria and ascidiacea are rich in bioactive metabolites (blunt et al. 2013 and previous reports) and feeding repellents (koplovitz et al. 2009; núñez-pons et al. 2010). our cnidarian samples comprised hydrozoans and anthozoans whereas the ascidians included colonial species. soft corals and colonial ascidians are highly energetic (16 and 15 kj g �1 dry wt, respectively; slattery & mcclintock 1995; mcclintock et al. 2004), while hydroids and gorgonians are also quite nutritious (coma et al. 1998). ether fraction yields may illustrate this outcome: ascidians ca. 4.9%; soft corals ca. 3.3%; gorgonians ca. 1.2% (table 1). antarctic cnidarians and ascidians represent transitory biosubstrata for amphipods in shelf communities not dominated by sponges or algae (dayton et al. 1974; de broyer et al. 2001). in the present study, most samples were chemically defended, but other tactics might co-occur in these groups. hydrozoans use lipophilic as well as nematocyst-based defences even if considered redundant by the ot (herms & mattson 1992; stachowicz & lindquist 2000; lindquist 2002). staurotheca antarctica yielded a rich fraction deterrent to amphipods but inactive against sea stars. nematocysts may protect against asteroids, which seem particularly vulnerable when stinging happens on sensitive ambulacral feet or cardiac stomach mucosa, and syntheciidae hydroids are generally armoured with penetrating cnidos, often injecting polar proteinaceous venoms (shostak 1995; ostman 2000). thus, s. antarctica, in using repellent lipids against amphipods and nematocyst against asteroids, might contravene the ot. nonetheless, polar fractions may contain other defences not tested here. the hydroid symplectoscyphus glacialis (family sertulariidae) rarely presents penetrating nematocysts (shostak 1995), and its extract was significantly deterrent to both predators. regarding anthozoa, umbellula antarctica is a pennatulacean with a fibrous axis and a distal crown of giant (3�4 cm long) polyps (pasternak 1962; dolan 2008). both regions revealed distinct bioactivities and thin layer chromatography profiles, suggesting that lipid repellents were present only in the axis. the chemically unprotected and exposed polyparium is presumed to either rely on hydrophilic repellents and/or on nematocysts for defence, which actively participate in capturing prey (dolan 2008). autozooid nematocysts in the pennatulid sea pansy, renilla kollekeri, keep sea star predators away in a similar way (kastendiek 1976). the fibrous stalk of u. antarctica, denuded of nematocysts, did possess deterrents for amphipods. since alternative defences seem to occur in different body regions, ot and odt could both be sustained for u. antarctica. soft corals and gorgonians generally lack stinging nematocysts and likely rely on chemical defence (sammarco & coll 1992), as reflected in our results. only one fraction from primnoisis antarctica sample 1 was accepted by both consumers, and one extract from thouarella laxa was only suitable for the star. both fraction yields were less abundant than active conspecific extracts (table 1; fig. 1). many colonial ascidians protect their common external tunic with alternative tactics other than organic deterrents. for example, the antarctic species distaplia cylindrica and d. colligans combine lipidic defences and inorganic chemistry (acid, heavy metals; mcclintock et al. 2004; koplovitz et al. 2009). none of the species studied here showed a similar kind of defence (koplovitz et al. 2009; lebar et al. 2011). moreover, tunics may be nutritiously unattractive (mcclintock et al. 1991; pisut & pawlik 2002). among our synoicum adareanum samples, as is common in this species (varela 2007), there were three colour morphs; black and white (b&w), brown (br), and orange (o) morphotypes. the dissected o sample exhibited no defence allocation. in contrast, the internal extracts of both b&w samples caused strong rejection by o. validus and chemical defences towards antarctic keystone predators l. núñez-pons & c. avila 8 (page number not for citation purpose) citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 c. femoratus, while the external colonial tunic fractions were accepted by sea stars. b&w morph tunics were thick and tough and yielded poorer lipophilic fractions than their inner regions (table 1, fig. 1). to ward off predators, the b&w samples rely on lipophilic distasteful metabolites in the inner tissues. smaller quantities of these deterrents present in the external tunic may work together with low nutritional value to discourage external asteroid attack. the participation of polar products, again, cannot be ruled out. finally, the rich apical fraction from a b&w sample containing siphon mouths and common cloaca, was rejected only by the sea star. the allocation of deterrent activities prevalent in internal regions of b&w s. adareanum samples might provide support for the odt. colonial ascidians invest much energy for reproduction and tend to produce complex, chemically-defended larvae (lambert 2005). external damages due to eventual predation attacks rarely kill colonies but instead cause reversible injuries on the outer protective common tunic and death of some clonal zooids. hence, storing repellents in inner tissues (gonads), which, in this case, are more vital for species survival than the outer colonial tunic, is consistent with the odt (rhoades & gates 1976). in less represented taxa, the abundant extract from the hemichordate pterobranch displayed no repellency in any assay. these animals may not need chemical protection since they live hidden from major enemies inside the coenoecia, colonial encasements hardened with agglutinated foreign material (ridewood 1911; brusca & brusca 2003). again, the existence of polar deterrents cannot be discarded. in contrast, the bryozoan and holothurian fractions reflected the presence of feeding deterrents against o. validus. the calcified bryozoan isoschizoporella secunda afforded poor extract yields. it harbours sessile ‘‘trap-door’’ avicularia that are proposed to function as active mechanical deterrents to zooid-level predators (amphipods, nematodes, polychaetes) and as secretion sites for bioactive compounds (carter et al. 2010). hence, this branched bryozoan could avoid amphipod attacks through entrapments of appendages by avicularia and rely on chemistry against asteroids (bryan et al. 1998). finally, the elpidiid holothurian peniagone vignioni, with an ability to swim (wigham et al. 2008), may escape from many bottom-dwelling consumers. thus, repellents against sea stars would only be useful while the animal is feeding on the substrate surface (table 1; fig. 1). concluding remarks antarctic benthic ecosystems are considered stable but adapted to marked seasonalities of nutrient supply and composed of many defended sessile species with long lifespans subjected to intense generalist predation (dayton et al. 1974; avila et al. 2008). most defensive deterrents do not totally prevent attacks, but they reduce the attractiveness of the organism compared to other coexisting prey, while generalist feeding mitigates possible toxicities of secondary metabolites and compensates for poor-quality diets (bernays et al. 1994; stachowicz et al. 2007; sotka et al. 2009). combined effects of nutrient content with defensive chemicals are not appreciable prior to ingestion and may affect predators differently. in sea stars, gustation likely takes place with the cardiac stomach or the ambulacral system (sloan 1980; kidawa 2005), whereas scavenging lysianassoid amphipods have well-developed gustatory gnathopods (kaufmann 1994). amphipods seem particularly sensitive to lipidic deterrents (duffy & paul 1992; cruz-rivera & hay 2003), as we have observed in cheirimedon femoratus (núñez-pons et al. 2012). accordingly, macroalgae and invertebrates mostly yield lipidsoluble repellents (sotka et al. 2009). our investigations have aimed at improving our understanding of the ecological importance of lipophilic metabolites in antarctic organisms, which require sizable lipid reserves. we are, however, aware of the limitations of testing only ees in terms of the relative difference among consumers and how these can interact with distinct metabolite types. further studies in progress will analyse other fractions. differences in extraction protocols, bioassay methodologies (actual ingestion versus chemo-sensitive reactions in sea stars) and experimental predatory amphipod species, as well as the distance between collection sites, make it difficult to combine our results with those of other antarctic studies in order to draw strong conclusions (for reviews see avila et al. 2008; mcclintock et al. 2010). further studies should seek to fill in the gaps of understanding antarctic chemical ecology. acknowledgements we thank m. rodrı́guez-arias, j. vázquez, b. figuerola, f.j. cristobo and s. taboada for their invaluable help during the antarctic cruises. comments from the reviewers were very helpful, as well as the english refinements of m. keinath. thanks are due to the crew of the rv polarstern. the marine technology unit (utm; under the spanish national research council [csic]), the crew of the rv las palmas and the staff of gabriel de castilla station gave logistic support. we are thankful to a. gómez-garreta, a. ribera-siguán, p. rı́os, m. varela and a. bosch for taxonomical assistance. funding was provided by the ministry of science and innovation of spain (projects cgl2004-03356/ant, cgl2007-65453/ ant and cgl2010-17415/ant). l. núñez-pons & c. avila chemical defences towards antarctic keystone predators citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 references amsler c.d., iken k., mcclintock j.b., amsler m.o., peters k.j., hubbard j.m., furrow f.b. & baker b.j. 2005. comprehensive evaluation of the palatability and chemical defenses of subtidal macroalgae from the antarctic peninsula. marine ecology progress series 294, 141�159. amsler m.o., mcclintock j.b., amsler c.d., angus r.a. & baker b.j. 2009. an evaluation of sponge-associated amphipods from the antarctic peninsula. antarctic science 21, 579�589. atwater w.o. & benedict f.g. 1902. experiments on the metabolism of matter and energy in the human body, 1898� 1900. washington, dc: government printing office. aumack c.f., amsler c.d., mcclintock j.b. & baker b.j. 2010. chemically mediated resistance to mesoherbivory in finely branched macroalgae along the western antarctic peninsula. european journal of phycology 45, 19�26. avila c., iken k., fontana a. & gimino g. 2000. chemical ecology of the antarctic nudibranch bathydoris hodgsoni eliot, 1907: defensive role and origin of its natural products. journal of experimental biology and ecology 252, 27�44. avila c., taboada s. & núñez-pons l. 2008. marine antarctic chemical ecology: what is next? marine ecology 29, 1�70. barthel d. 1995. tissue composition of sponges from the weddell sea, antarctica*not much meat on the bones. marine ecology progress series 123, 149�153. bernays e.a., bright k.l., gonzalez n. & angel j. 1994. dietary mixing in a generalist herbivore*tests of two hypotheses. ecology 75, 1997�2006. blunt j.w., copp b.r., keyzers r.a., munro m.h.g. & prinsep m.r. 2013. marine natural products. natural products reports 30, 237�323. bregazzi p.k. 1972. life cycles and seasonal movements of cheirimedon femoratus and tryphosella kergueleni crustacea amphipoda. british antarctic survey bulletin 30, 1�34. brusca r.c. & brusca g.j. 2003. invertebrates. 2nd edn. sunderland, ma: sinauer associates. bryan p.j., kreider j.l. & qian p.y. 1998. settlement of the serpulid polychaete hydroides elegans (haswell) on the arborescent bryozoan bugula neritina (l.): evidence of a chemically mediated relationship. journal of experimental biology and ecology 220, 171�190. bucolo p., amsler c.d., mcclintock j.b. & baker b.j. 2011. palatability of the antarctic rhodophyte palmaria decipiens (reinsch) rw ricker and its endo/epiphyte elachista antarctica skottsberg to sympatric amphipods. journal of experimental marine biology and ecology 396, 202�206. carter m.c., gordon d.p. & gardner j.p.a. 2010. polymorphism and vestigiality: comparative anatomy and morphology of bryozoan avicularia. zoomorphology 129, 195�211. coma r., ribes m., gili j.m. & zabala m. 1998. an energetic approach to the study of life-history traits of two modular colonial benthic invertebrates. marine ecology progress series 162, 89�103. cronin g. & hay m.e. 1996. induction of seaweed chemical defenses by amphipod grazing. ecology 77, 2287�2301. cruz-rivera e. & hay m.e. 2003. prey nutritional quality interacts with chemical defenses to affect consumer feeding and fitness. ecological monographs 73, 483�506. dayton p.k., robillia g.a., paine r.t. & dayton l.b. 1974. biological accommodation in benthic community at mcmurdo sound antarctica. ecological monographs 44, 105�128. de broyer c., lowry j.k., jazdzewski k. & robert h. 2007. catalogue of the gammaridean and corophiidean amphipoda of the southern ocean, with distribution and ecological data. bulletin de l’institut royal des sciences naturelles de belgique: biologie 77, supplement 1. bruxelles: royal belgian institute of natural sciences. de broyer c., scailteur y., chapelle g. & rauschert m. 2001. diversity of epibenthic habitats of gammaridean amphipods in the eastern weddell sea. polar biology 24, 744�753. dolan e. 2008. phylogenetics, systematics and biogeography of deepsea pennatulacea (anthozoa: octocorallia). evidence from molecules and morphology. phd thesis, university of southamptom. duffy j.e. & paul v.j. 1992. prey nutritional quality and the effectiveness of chemical defenses against tropical reef fishes. oecologia 90, 333�339. furrow f.b., amsler c.d., mcclintock j.b. & baker b.j. 2003. surface sequestration of chemical feeding deterrents in the antarctic sponge latrunculia apicalis as an optimal defense against sea star spongivory. marine biology 143, 443�449. gomez i. & westermeier r. 1995. energy contents and organic constituents in antarctic and south chilean marine brown algae. polar biology 15, 597�602. graeve m., dauby p. & scailteur y. 2001. combined lipid, fatty acid and digestive tract content analyses: a penetrating approach to estimate feeding modes of antarctic amphipods. polar biology 24, 853�862. harvell c.d. 1984. predator-induced defense in a marine bryozoan. science 224, 1357�1359. harvell c.d. 1990. the ecology and evolution of inducible defenses. quaterly review of biology 65, 323�340. hay m.e., duffy j.e. & pfister c.a. 1987. chemical defense against different marine herbivores*are amphipods insect equivalents? ecology 68, 1567�1580. heck k.l. & valentine j.f. 1995. sea-urchin herbivory* evidence for long-lasting effects in subtropical seagrass meadows. journal of experimental marine biology and ecology 189, 205�217. herms d.a. & mattson w.j. 1992. the dilemma of plants*to grow or defend. quaterly review of biology 67, 283�335. huang y.m., amsler m.o., mcclintock j.b., amsler c.d. & baker b.j. 2007. patterns of gammaridean amphipod abundance and species composition associated with dominant subtidal macroalgae from the western antarctic peninsula. polar biology 30, 1417�1430. iken k., avila c., fontana a. & gavagnin m. 2002. chemical ecology and origin of defensive compounds in the antarctic chemical defences towards antarctic keystone predators l. núñez-pons & c. avila 10 (page number not for citation purpose) citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 nudibranch austrodoris kerguelenensis (opisthobranchia: gastropoda). marine biology 141, 101�109. kastendiek j. 1976. behavior of the sea pansy renilla kollikeri pfeffer (coelenterata: pennatulacea) and its influence on the distribution and biological interactions of species. biological bulletin 151, 518�537. kaufmann r.s. 1994. structure and function of chemoreceptors in scavenging lysianassoid amphipods. journal of crustacean biology 14, 54�71. kidawa a. 2005. behavioural and metabolic responses of the antarctic sea star odontaster validus to food stimuli of different concentration. polar biology 28, 449�455. koplovitz g., mcclintock j.b., amsler c.d. & baker b.j. 2009. palatability and chemical anti-predatory defenses in common ascidians from the antarctic peninsula. aquatic biology 7, 81�92. krapp r.h., berge j., flores h., gulliksen b. & werner i. 2008. sympagic occurrence of eusirid and lysianassoid amphipods under antarctic pack ice. deep-sea research part ii 55, 1015� 1023. kunzmann k. 1996. associated fauna of selected sponges (hexactinellida and demospongiae) from the weddell sea, antarctica. reports on polar research 210. bremerhaven: alfred wegener institute. lambert g. 2005. ecology and natural history of the protochordates. canadian journal of zoology 83, 34�50. lebar m.d., luttenton l., mcclintock b., amsler c.d. & baker b. 2011. accumulation of vanadium, manganese, and nickel in antarctic tunicates. polar biology 34, 587�590. lindquist n. 2002. tridentatols d-h, nematocyst metabolites and precursors of the activated chemical defense in the marine hydroid tridentata marginata (kirchenpauer 1864). journal natural products 65, 681�684. lindquist n. & hay m.e. 1995. can small rare prey be chemically defended*the case for marine larvae. ecology 76, 1347�1358. mcclintock j.b. 1987. investigation of the relationship between invertebrate predation and biochemical composition, energy content, spicule armament and toxicity of benthic sponges at mcmurdo sound, antarctica. marine biology 94, 479�487. mcclintock j.b. 1994. trophic biology of antarctic echinoderms. marine ecology progress series 111, 191�202. mcclintock j.b., amsler c.d. & baker b. 2010. overview of the chemical ecology of benthic marine invertebrates along the western antarctic peninsula. integrative and comparative biology 50, 967�980. mcclintock j.b., amsler m.o., amsler c.d., southworth k.j., petrie c. & baker b.j. 2004. biochemical composition, energy content and chemical antifeedant and antifoulant defenses of the colonial antarctic ascidian distaplia cylindrica. marine biology 145, 885�894. mcclintock j.b., amsler m.o., koplovitz g., amsler c.d. & baker b.j. 2009. observations on an association between the dexaminid amphipod polycheria antarctica f. acanthopoda and its ascidian host distaplia cylindrica. journal of crustacean biology 29, 605�608. mcclintock j.b. & baker b.j. 2001. marine chemical ecology. boca raton, fl: crc. mcclintock j.b., heine j., slattery m. & weston j. 1991. biochemical and energetic composition, population biology, and chemical defense of the antarctic ascidian cnemidocarpa verrucosa lesson. journal of experimental marine biology and ecology 147, 163�175. montgomery w.l. & gerking s.d. 1980. marine macroalgae as foods for fishes*an evaluation of potential food quality. environmental biology of fishes 5, 143�153. núñez-pons l., forestieri r., nieto r.m., varela m., nappo m., rodrı́guez j., jiménez c., castelluccio f., carbone m., ramos-esplá a., gavagnin m. & avila c. 2010. chemical defenses of tunicates of the genus aplidium from the weddell sea (antarctica). polar biology 33, 1319�1329. núñez-pons l., rodrı́guez-arias m., gómez-garreta a., ribera-siguan a. & avila c. 2012. feeding deterrency in antarctic marine organisms: bioassays with the omnivore amphipod cheirimedon femoratus. marine ecology progress series 462, 163�174. ostman c. 2000. a guideline to nematocyst nomenclature and classification, and some notes on the systematic value of nematocysts. scientia marina 64, 31�46. pasternak t.a. 1962. pennatulids of the genus umbellula cuvier from the antarctic and subantarctic. issled faune morei 1, 105�128. paul v.j. 1992. ecological roles of marine natural products. ithaca, ny: comstock publications. paul v.j., arthur k.e., ritson-williams r., ross c. & sharp k. 2007. chemical defenses: from compounds to communities. biological bulletin 213, 226�251. peters k.j., amsler c.d., mcclintock j.b., van soest r.w.m. & baker b.j. 2009. palatability and chemical defenses of sponges from the western antarctic peninsula. marine ecology progress series 385, 77�85. pisut d.p. & pawlik j.r. 2002. anti-predatory chemical defenses of ascidians: secondary metabolites or inorganic acids? journal of experimental marine biology and ecology 270, 203�214. rhoades d.f. & gates r.g. 1976. toward a general theory of plant antiherbivore chemistry. recent advances in phytochemistry 10, 168�213. ridewood w.g. 1911. cephalodiscus. national antarctic expedition 1901�1904. natural history 2. zoology. london: british museum. sammarco p.w. & coll j.c. 1992. chemical adaptations in the octocorallia: evolutionary considerations. marine ecology progress series 88, 93�104. sánchez j.a., gil m.f., chasqui l.h. & alvarado e.m. 2004. grazing dynamics on a caribbean reef-building coral. coral reefs 23, 578�583. shostak s. 1995. nematocyst database. accessed on the internet at http://www.pitt.edu/�sshostak/cnidocyst_database/ on 6 march 2014 l. núñez-pons & c. avila chemical defences towards antarctic keystone predators citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 11 (page number not for citation purpose) http://www.pitt.edu/~sshostak/cnidocyst_database/ http://www.pitt.edu/~sshostak/cnidocyst_database/ http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 slattery m. & mcclintock j.b. 1995. population structure and feeding deterrence in three shallow-water antarctic soft corals. marine biology 122, 461�470. sloan n.a. 1980. aspects of the feeding biology of asteroids. oceanography and marine biology: an annual review 18, 57� 124. sokal r.r. & rohlf f.j. 1995. biometry: the principles and practice of statistics in biological research. new york: w.h. freeman and co. sotka e.e., forbey j., horn m., poore a.g.b., raubenheimer d. & whalen k.e. 2009. the emerging role of pharmacology in understanding consumer�prey interactions in marine and freshwater systems. integrative and comparative biology 49, 291�313. stachowicz j.j., bruno j.f. & duffy j.e. 2007. understanding the effects of marine biodiversity on communities and ecosystems. annual review of ecology, evolution and systematics 38, 739�766. stachowicz j.j. & lindquist n. 2000. hydroid defenses against predators: the importance of secondary metabolites versus nematocysts. oecologia 124, 280�288. taboada s., núñez-pons l. & avila c. 2012. feeding repellence of antarctic and sub-antarctic benthic invertebrates against the omnivorous sea star odontaster validus koehler, 1906. polar biology 36, 13�25. thoms c., schupp p.j., custódio m.r., lôbo-hajdu g., hajdu e. & muricy g. 2007. chemical defense strategies in sponges: a review. in m.r. custódio et al. (eds.): porifera research: biodiversity, innovation and sustainability. pp. 627� 637. rio de janeiro: national museum of brazil. toth g.b., karlsson m. & pavia h. 2007. mesoherbivores reduce net growth and induce chemical resistance in natural seaweed populations. oecologia 152, 245�255. vader w. 1984. notes on norwegian marine amphipoda 7. amphipod associates of geodia sponges in western norway. fauna norvegian series a 5, 14�16. varela m. 2007. contribución al conocimiento de las ascidias coloniales (chordata: tunicata) de la antártida occidental y región magallánica. (contribution to the knowledge of colonial ascidians [chordata: tunicata] from occidental antarctica and magellan regions.) phd thesis, universidad de alicante. vermeij g.j. 1994. the evolutionary interaction among species: selection, escalation, and coevolution, annual review of ecology. evolution and systematics 25, 219�236. wigham b.d., galley e.a., smith c.r. & tyler p.a. 2008. interannual variability and potential for selectivity in the diets of deep-water antarctic echinoderms. deep-sea research part ii 55, 2478�2490. zamzow j.p., amsler c.d., mcclintock j.b. & baker b.j. 2010. habitat choice and predator avoidance by antarctic amphipods: the roles of algal chemistry and morphology. marine ecology progress series 400, 155�163. chemical defences towards antarctic keystone predators l. núñez-pons & c. avila 12 (page number not for citation purpose) citation: polar research 2014, 33, 21624, http://dx.doi.org/10.3402/polar.v33.21624 http://www.polarresearch.net/index.php/polar/article/view/21624 http://dx.doi.org/10.3402/polar.v33.21624 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile (none) /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff00530065007400740069006e0067007300200066006f00720020007400680065002000520061006d007000610067006500200077006f0072006b0066006c006f0077002e> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice the late weichselian-holocene transition in the barents sea: sedimentological and early diagenetic studies carl fredrik forsberg forsberg. c. f. 1987: the late weichselian-holocene transition in the barents sea: sedimentological and early diagenetic studies. polar research 5 n . s . , 289-290. carl fredrik forsberg, norwegian geotechnical institute, p . o . box 40 t h e n , 0801 oslo 8, norway. gravity cores and grab samples from the barents sea (fig. 1) were studied with respect to mineralogy, grain size distribution. total carbon content and ‘rock eval’ pyrolysis. the samples were classified as either late weichselian or holocene accord ing to bjarlykke et al. (1978) and elverhoi & solheim (1983). the grain size distributions show as expected that the late weichselian sediments are coarser than those from the holocene. the ‘rock eval’ results show that while the carbon in the late weichselian sediments is almost exclusively re worked with the greatest concentration in the 2-6 ym fraction, the carbon in the holocene sediments contains increasingly ... location pap fig. 1. the sample locations studied and the approximate posi tion of the oceanic polar front. subscript ‘g’ indicates grab samples. greater amounts of primary carbon up towards the sea bed with the highest content in the < 2 y m fraction. there is a close connection between the period of annual ice cover and the carbon content in the holocene sediments (fig. 2). the holocene sediments contain significant amounts of smec tite and mixed layered minerals. whereas the late weichselian sediments d o not. these minerals are indications of the holo cene deposits having, at least partially, a source outside the barents sea. unlike the primary carbon the mineralogical distri bution in the holocene sediments is not much affected by the present hydrological regimes. the late weichselian glacial and climatic conditions were too severe to support primary production of carbon, and sediments from this period contain only carbon reworked from local sedi mentary rocks. with the onset of the holocene and the accompanying climatic amelioration primary production increased, allowing sedimentation of first cycle algal debris. a combination of deglaciation and the accompanying eustatic rise in sea level freed a potential sediment transportation path from the arctic ocean. the shelf and land masses surrounding the arctic ocean thus became potential sediment source areas for the barents sea. in the absence of any large rivers running into the barents sea one of the main agents of holocene sediment supply is deemed to be dirty sea ice which may originate on the siberian shelf. published grainsize distributions of sediments from sea ice (sharma 1979) compare very well with the silt and clay sized sub-populations from the sediments in the barents sea. thus. the late weichselian to holocene transition in the barents sea seems to have been accompanied by the onset of primary production in the water masses and a change from sedimentation of locally derived material by glacial processes to intrabasinal reworking by marine processes and the supply of extrabasinal inorganic material by sea ice rafting. references bjerlykke, k . . bue, b. & elverhei, a. 1978: quaternary sedi ments in the northwestern part of the barents sea and their relation to the underlying mesozoic bedrock. sedimentology 25, 227-413. elverhbi, a . & solheim, a. 1983: the barents sea ice sheet a sedimentological discussion. polar research 1 n.s., 23-42. 290 carl fredrik forsberg 0.6. 0 . 5 . 0 . 4 0.3. 0 . 2 soutb north :::\ /*' i,&- \:i -----..: /* rock e v a l pyrolysis ye-- /' annual ice cover 10 . 8 . 6 . (months t 40 ' g r a m s r i e distributions ,/<--*\ 30 ' 20 10 . ' 3 0 . 4 . 0 2 . 0 . 1 . 0 nineralog). i total c a r b o n content ( * 1 /;. **-----. ' . . . . . ------- :>--a -. -.. ...._. *-.20-63 urn t- . --- > 63 illite/smectite chlorite/kaolinio 5 3 / 5 2 sr/s2 , , 1 10 1 4 16 19 29 5 0 c o r e numbers fig. 2 summary of the main results for the surface core samples. the period of ice coverage is from vinle (1977) sharma. g . d. 1979: the alaskan sher. hydrographic, sedivinje. t. 1977: frequency distribution of sea ice in the mentary and geochemical environments. springer. n.y. 488 greenland and barents seas, 1971-1980. u . s . d e p . pp commerce. net. technical information. early holocene environment on bjornoya (svalbard) inferred from multidisciplinary lake sediment studies b a r b a r a wohlfarth, geoffrey lemdahl, siv olsson, thomas persson. ian snowball. jonas islng and viv jones wohlfarth. b . , lemdahl. g . . olsson, s . , persson. t., snowball. 1.. ising, j . & jones, v . 1995: early holocene environment on bjorneya (svalbard) inferred from multidisciplinary lake sediment studies. polar research 1 4 ( 2 ) . 253-215. bjornoya, a small (178 km2) island situated between the mainland of norway and southern spitsbergen, provides the opportunity for the reconstruction of early holocene terrestrial and limnic palaeoenvironments in the southwestern barents sea. the ams ''c dating technique, geochemical, mineral magnetic, micro and macrofossil analyses were applied lo sediments recovered from lake stevatnet and the results are interpreted in terms of palaeoenvironmental conditions between 9800 and 8300 i4c b p . after the dis appearance of local glaciers before ca 9800 14c bp, the lake productivity increased rapidly at the same time as pioneer plant communities developed on soils which gradually became more stable. insect data indicates that strong seasonal contrasts with mean july temperatures around 9°c and mean january temperatures around -12°c prevailed between 9500 and 8300 i4c bp. these high summer temperatures, possibly as much as 4-5°c higher than the present, favoured the development of a flora including dryas and angelica cf. archangelica. the enhanced freeze/thaw processes led to an increased erosion of minerogenic and organic material. after 8000 ''c bp the temperatures may have gradually declined. the environmental reconstruction derived from our data set supports the conceptual insolation model which proposes maximum holocene seasonality for the northern hemisphere at ca 9000 i4c bp. barbara wohlfarth, geoffrey lemdahl, siu olsson, thomas persson, ian snowball and jonas ising. department of quaternary geology, tornauiigen 13. s-22363 lund, sweden; viu jones, department of geography, unicrersiry college london, 26 bedford way, londotl w c l h oap, u . k . introduction the island of bjorncbya is situated in the south western barents sea, between the mainland of norway and the southern end of svalbard (fig. 1a). during the last glacial maximum (ca 18,000 14c bp), the barents sea ice sheet reached west to the continental shelfbreak and a glacier, possibly dry-based, covered b j ~ r n ~ y a (elverhei & solheim 1983; vorren et al. 1988; e l v e r h ~ i et al. 1990; vorren 1992; elverhei et al. 1995). the ice receded in two steps, firstly at ca 14,800 14c bp from the outer shelf and the southwestern barents sea and secondly at ca 13,000-12,000 14c bp from the inner and shallower shelf (elverhoi et al. 1995). these separate recessions correspond to meltwater signals recorded in marine cores between 15,000-13,000 14c bp (hald & dokken 1995). the timing of the decay of the barents sea ice sheet is also indicated by an influx of meltwater from major siberian rivers into the central arctic ocean slightly before 14,500 l4c bp (stein et al. 1994). at ca 12,500 14c b p the first warming of the ocean surface is recorded in marine sediment cores from the continental margn off western svalbard and the western barents sea (hald & dokken 1995). mollusc dates from the northern barents sea, and emergence curves from kong karls land, indicate that the barents sea ice sheet had disappeared by ca 10,000 i4c b p (sal vigsen 1981; elverhei et al. 1990; bondevik et al. 1995; hjort et al. 1995). this date agrees well with oxygen isotope data from marine cores which show a rapid temperature increase of 2-3°c between 10,000-9500 14c bp (hald & dokken 1995) and indicate that warm atlantic water replaced cold arctic water in the western and southeastern barents sea (hald & vorren 1987; vorren et al. 1988). bulk sediment 14c dates obtained on basal lake sediments from bjerneya have been used to date the beginning of the organic production in one of the lakes to between 11,200 -c 500 and 8300 + 1200/-1000 lilt bp (hyvarinen 1968, 1970; ols son 1968). however, since the sediments con tained large quantities of coal particles derived 19 " 0 0 ' 1 9 " 1 0 ' i i b 1 9 " 0 0 1 9 " 1 0 ' l e g e n d * l ak es c or ed b y h yv er in en ( 1 9 6 8 ) -! e qu is et ur n ar ve ns e. 4 l u z u la a rc ua ta , + d es ch ar np si a al pi na , 0 p oa a lp in a, 0 p hi pp si a al gi da , r t ph ip ps ta c on ci nn a. * f es tu ca v iv ip ar a, jk sa lix h er ba ce a, po la ri s, * sa lix r et ic ul at a. 0 k oe ni gi a is la nd ic a, b k o xy ri a di gy na . + po ly go nu rn vi vi pa ru rn , 0 s ag in a in te rm ed ia , a c er as ti ur n ar ct ic ur n, v c er as ti ur n re ge lii , c s il en e ac au li s. # r an un cu lu s py gr na eu s, ce rn ua . k s ax if ra ga ni va lis , a s ax if ra ga r iv da ri s, 4 sa xi fr ag a te nu is sa lix d ra ba a lp in a. + d ra ba n or ve gi ca , 0 s ax if ra ga fi g. 1 . a . g eo gr ap hi c po si ti on o f b j~ rn ~ y a . b . t op og ra ph ic m ap o ve r b j~ rn ~ y a . t he n or th er n, r at he r fl at p ar t of t he i sl an d is s it ua te d be lo w t he 4 0 m c on to ur l in e. t he m ou nt ai n ar ea s to t he s ou th a nd s ou th ea st r ea ch c a 50 0m a .s .1 . t he l ak es c or ed b y h yv ar in cn ( 19 68 ) d ur in g th e st oc kh ol m u ni ve rs ity s va lb ar d e xp ed it io n in t he y ea rs 1 96 51y 66 a rc m ar ke d by a rr ow s. c . t op og ra ph ic m ap o ve r th e su rr ou nd in gs o f s te va tn et . t he c or in g po in ts s t 2 -s t 1 a re m ar ke d w ith f ill ed c ir cl es . t he v eg et at io n ar ou nd t he l ak e is a cc or di ng t o e ng el sk j0 n (1 98 6, m ap s 154 ). early holocene environment on bj@rn@ya (svalbard) 255 from the bedrock, t h e reliability of the dates was questioned by olsson (1968). the appreciation of the problems associated with the reliability of the original radiocarbon dates from b j ~ r n ~ y a led to a re-investigation of t h e sediments of some lakes within the frame of the p o n a m project during august 1993. during an earlier svalbard expedition organised by stockholm university, hyvarinen (1968) took sediment cores from 18 lakes situated between 10 and 100m a.s.1. (fig. 1b). the holocene veg etation history was reconstructed on the basis of pollen analysis of three lake sequences and was compared to the development on svalbard and northern fennoscandia (hyvarinen 1968, 1970). although h o r n & orvin (1928) had described marine terraces/plains of denudation, which they interpreted as younger than the last deglaciation, diatom analyses conducted o n lakes at different altitudes did not reveal any marine influence on their sediments (hyvarinen 1968). during the august 1993 field work we obtained sediment cores from three lakes, vestre skinkevatnet, @stre skinkevatnet and stevatnet, situated in the northern part of the island. two of these lakes, vestre skinkevatnet and stevatnet had been cored earlier by hyvarinen (1968) who described fairly long sediment sequences. t h e general litho stratigraphy recovered in all three lakes compares well to hyvarinen’s (1968) earlier descriptions. in this paper we present new results, obtained from geochemical, palynological, entomological, mineral magnetic, plant macrofossil and diatom analyses of sediment cores recovered from ste vatnet. t h e results, which include new ams 14c dates, a r e used to reconstruct the early holocene environment on b j @ r n ~ y a and are compared to earlier investigations on bjornoya and in other arctic regions. geography, climate, bedrock geology and vegetation t h e island is surrounded by steep cliffs and has a surface area of 178 km’. t h e main geographic units a r e the fairly flat “northern plain”, which extends from southwest to northeast, with alti tudes rarely above 40 m a.s.l., and the southern/ southeastern part, dominated by hills and moun tains that rise u p to 500 m a.s.1. most of the lakes a r e situated in the “northern plain”, which covers a surface area of ca 110 km2 (fig. i b ) . many lakes a r e small, extremely shallow and dry out during summer. h o r n & orvin (1928) observed that the ground thawed t o a depth of ca 0.75 m and perma frost reached down to 60-70 m below the surface. however, unfrozen ground below lake bottoms was reported by fleetwood et al. (1974). perma frost features such as circles, polygones, nets and stribes are especially common o n the limestone terrain. t h e maritime arctic climate of bjomoya is governed by the norwegian current along the western coast and an arctic stream which comes from the east and the north, causing cold air masses to move southwards around the island. dense fog frequently occurs during the summer months (july: 24 days, august: 22 days) and is a characteristic phenomenon f o r bj0rnoya. the average yearly temperatures range around ca 1 s ” c ; the average monthly air temperatures recorded for the time period 1931-1960 range from between -5.7” and -7.2”c for the coldest months january-march and from between +4.5” and +5.0°c for the warmest months, july and august (steffensen 1969,1982; e n g e l s k j ~ n 1986). since average precipitation does not exceed 400 mm/yr, the high humidity of the ground and t h e vegetation cover is maintained by the low temperatures and the heavy cloud and fog cover (engelskjon 1986). t h e bedrock is mainly composed of devonian, carboniferous and permian sandstones, shales. coal seams. conglomerates and fossiliferous lime stones (horn & orvin 1928; worsley & edwards 1976) (fig. 2a). t h e oldest and youngest rocks, the dolomites of the hecla hoek formation and the triassic sandstones and shales, are only found in the mountain areas to the south and southeast. the strong relationship between vegetation cover and bedrock o n b j ~ r n ~ y a has been described by engelskjon (1986), who carried out a detailed survey of the island’s plant communities. although the vegetation can be compared to other areas adjacent t o the barents sea, several differences exist e.g. between t h e spitsbergen and b j ~ r n ~ y a floras. compared to spitsbergen, species adapted to cold and water-logged con ditions a r e more common on bjornoya, whereas species demanding higher summer temperatures such as e.g. salix glauca, betula nana. dryas octopetala, cassiope tetragona and empetriim her maphroditum are absent (engelskjon 1986). most of the island’s eutrophic species concentrate on t h e lime-rich parts, where weathered material 256 b . wohlfarrh er id. e y g, p t early holocene environment on bjgirn@ya (soalbard) 257 from dolomites. limestones and m a r k yields an alkaline lithosol with a high c a content (eng elskjon 1986). t h e bedrock-vegetation-relationship is well exemplified in the surroundings of stevatnet and demonstrated in figs. 1 c and 2b. the soil which developed o n the “spirifer limestone”, a dark grey fossiliferous limestone north of the lake (horn & orvin 1928), clearly supports a more extensive vegetation with species such as phippsia algida, salix herbacea, salix polaris. salix reti culata, oxyria digyna, sagina intermedia, ranun culus pygmaeus, draba alpina. saxifraga nioalis and saxifraga renuis ( e n g e l s k j ~ n 1986). o n the western shore of stevatnet the so-called “ambi gua limestone” series occurs, characterised by massive grey limestones, red and violet mottled limestones and red sandstones (horn & orvin 1928). similar t o the eastern shore of the nearby lake haussvatnet only a sparse vegetation cover with salix reticulata is found ( e n g e l s k j ~ n 1986). t h e soils which develop o n the “fusulina lime stone” and the “ambigua limestone” are alkaline and yield a high content of c a (engelskj0n 1986), which explains the more extensive vegetation cover north and east of stevatnet. the “red conglomerate” south of stevatnet comprises sandstones, calcareous sandstones and conglom erates ( h o r n & orvin 1928). it is highly fissile and flakey, and shows a red and yellowish-green colour. t h e “ursa sandstone” east of stevatnet forms large and coarse blockfields. it is a white to grey massive sandstone with flakes of muscovite and biotite and fairly large amounts of pyrite. the lithosol of the “ursa sandstone” is slightly acid. horn & orvin (1928) and keilhau (1831) described that the intercalated shaley layers in the ‘wrsa sandstone” cause it to break up into coarse blockfields or stony polygons. apart from these stone polygons which support scattered mosses and lichen turfs, the sandstone areas are very poor in vegetation cover (engelskjm 1986). methods fieldwork stevatnet is situated at 46 m a.s.1. it has n o visible inflow, but drains north into the 12 m lower lake hellevatnet (fig. 1c). t h e core sites (st 1-st 4) were concentrated in the western part of the lake, because the water depth in the central part exceeded 6 m and the lake bottom in the eastern part was covered by stones and boulders of the “ursa sandstone”, which made coring very diffi cult. coring was carried out from a specially con structed boat with 1 m long strengthened russian corers with diameters of 7.5 and 5 cm. t h e overlap between the cores was ca 2 0 c m . t h e litho stratigraphy of the cores was described both in the field and later in t h e laboratory and revealed a fairly uniform stratigraphy, which made it easy to correlate between different cores, using the transition between layers 7 and 8 as a reference horizon (fig. 3). t h e detailed lithostratigraphic description of the four analysed cores ( s t 2 , 3 a . 3b, 4) is based o n the field descriptions and given in tables 1-4. mineral magnetic measurements routine mineral magnetic measurements were applied t o correlate cores and t o study the origin of t h e ferrimagnetic minerals present in the sedi ments. detrital magnetic minerals can provide information about the erosion history of lake catchments, while t h e identification of post depositional authigenic magnetic minerals may be used to reconstruct sedimentary redox conditions and trophic status. samples from all four cores were subsampled into contiguous plastic cubes (2 x 2 x 2 cm). cores s t 2 and s t 3a & b were subsampled immediately after collection. however, it was noted that severe oxidation of the cores had taken place during the time that had lapsed between core collection and measurement. sections of the cores with originally quite distinct fes stains had become bright red in colour. core st 4 was subsampled and measured approximately o n e year after collection, although the stratigraphy was still in its original form and the fes colour of the sediment had remained, only with surficial oxidation indicated. s i r m was induced in a maximum magnetic field of 1 tesla ( h h = 1 t ) with a redcliff pulse magnetiser, and the remanent magnetisation measured with a molspin “minispin” magnet ometer. t h e samples from s t 2 and s t 3 a & b were dried at 40°c after measurement to calculate mass specific si units. in the case of s t 4 magnetic susceptibility ( x ) was measured with a geofyzica brno “kappa” bridge and, in addition to the s i r m , a backfield irm induced at 100 m t was measured to calculate the s-ratio (stober & 258 b . wohlfarth er a / . s t 3 a 4.00 4.10 4 20 4 30 4 4 0 4 50 4.60 4 7 0 4 80 4 90 5 00 5 10 p) 5 2 0 0 f 5 3 0 ul & 5 4 0 m ' 5 5 0 5 0 5 6 0 5 7 0 l . 5 5.80 0 5.90 6.00 6.10 6.20 6.30 6 4 0 6.50 6 6 0 6 7 0 6 80 6 90 7 00 st 2 i i -1 \ \ \ \ \ lithology j=/ clay a g w i a sdt fes laminatior sand a gravel a stones . --. st 4 . . . . . . . . . , i , r a t l g r a p h ~ c corrclafion h c t w e c n cores st 7 . st 3.4. st 3 8 and st 4 . t h e four ams dates obtalned on mobsrs leaves (st 2 ) a r e indicated. as well a\ the samplss studied for macrofossils ( w e table 6) early holocene environment on bj@rn@ya (sualbnrd) 259 table 1. lithostratigraphy of core st 2 at a water depth of 4.20m. the lithostratigraphic description is based on the field description, where the different gyttja clay layers were mainly distinguished by colour differences. unit layer depth in m sediment description 111 20 4.20 -4.27 orange coloured silty gyttja clay. glb 19 18 17 15 14 4.27 -4.46 4.46 -4.80 4.80 -5.00 5.00 -5.15 5.15 -5.175 alternating layers of light-brown and black (fes-) coloured silty gyttja clay (ca 20 fes laminae), moss layer between 4.335-4.345 m , glb black (fes-) coloured, slightly silty gyttja clay with thin light brown layers (ca 50 fes laminae), glb light-brown silty gyttja clay with some moss remains and few fes laminae, glb light-brown silty gyttja clay with some moss remains and some fes spots, glb orange-yellow coloured silty gyttja clay with a fes lamina (0.5cm thick) at the upper and lower boundary, glb light-brcwn silty gyttja clay, black fes lamina at 5.20-5.21, g-slb 13 12 5.21 -5.25 brown silty gyttja clay, glb 5.175-5.2 1 11 5.25 -5.725 black (fes-) coloured clayey gyttja silt with single brown horizons ( 1 cm thick) and moss remains, g-slb black (fes-) silty gyttja clay with some moss remains. g-slb i1 9 5.725-5.775 light-brown silty gyttja clay with thin fes laminae. rich in mosses, glb 8 7 5.805-5.85 reddish clayey silt with some fes laminae. slb 6 5 5.775-5.805 5.85 -5.97 alternating layers of grey and reddish coloured silty gravelly clay with some small pebbles at 5.94, glb i 4-3 5.97 -6.05 yellow-red-grey coloured gravelly sandy silty clay, compact tublr 2 . lithostratigraphy of core st 3a at a water depth of 4.00 m. the lithostratigraphic description is based on the field description. where the different gyttja clay layers were mainly distinguished by colour difference%. unit layer 111 20 1’) 18 17 16 15 14 13 12 depth in m 4.n0 -4 05 4.05 -4.23 4.23 -4.50 4.50 -4.58 4 58 -4 83 4.83 -4.98 4.98 -4.99 4.99 -5.04 5.04 -5.085 sediment description ~~ ~ orange coloured silty gyttja clay, g1.b alternating layers of black (fes-) coloured and light-brown silty gyttja clay. zlb black (fes-) coloured silty gyttja clay with thin light-brown layers, glb red-brown silty gyttja clay, some fes laminae, glb black (fes-) coloured silty gyttja clay. higher clay content between 4.65-4.68 111. reddish-brown silty gyttja clay, with some moss remains and few fes laminae. slightly more clayey between 4.964.98. glb yellowish silty gyttja clay, black fes lamina at 4.99, some moss remains. slb reddish-brown silty gyttja clay with thin fes laminae. somc moss remains. glb yellowish silty gyttja clay, g-slb glb 11 10 5 085-5.37 5.37 -5.50 black (fes-) coloured. silty gyttja clay with few brown coloured laminae. some moss remains. slb brown-yellowish silty gyttja clay with some fes laminae ( 0 . 5 2 cm thick), some moss remains, slb black (fes-) silty gyttja clay. some moss remains, g-slb 11 9 5.50 -5.58 reddish-brown silty gyttja clay, faintly fes laminated, rich in mosses. slb 8 i 5.605-5.625 red-brown silty clay, very slb 5 5.67 -5.84 grey silty sandy gravelly clay 5.58 -5.605 i 6 5.625-5.67 grey-reddish silty clay, slb 260 b . wohljarth et a l . thompson 1979). these samples were not air dried and a r e currently under further inves tigation. certain sediment sections of s t 4 were selected for concentration of the magnetic min erals in accordance with the methods of snowball & thompson (1990). samples were freeze-dried to prevent oxidation of possible magnetic iron sulphides and the magnetic fractions were stored in acetone. t h e magnetic extracts were dispersed in epoxy resin and the magnetic hysteresis proper ties of the ferrimagnetic fraction measured with a pmc agfm-2900-2 magnetometer. t h e vari ation of magnetisation with temperature was investigated with the aid of a horizontal force translation balance at the university of edin burgh. x-ray diffraction analysis (xrd) was used to identify the magnetic minerals recovered in the magnetic concentrates. powder preparations were prepared of magnetic extracts and x-ray scanned over the region 15-55" 2 8 using a philips diffractonieter with c u ko-radiation. grain size and geochrwistry the grain-size distribution of samples from cores st 3 a & b was performed by sieving pre-weighed samples through a 63 pm sieve. t h e coarse frac tions were further sieved. dried and weighed, while the fine fractions were analysed on a sedi graph 5000 e t (micromeritics) after defloc culation in na,p?o:. the results were re calculated to bulk samples. total carbon content was determined on cores s t 3 a & b by stepped heating of the samples in oxygen in a leco furnace, which measures the coz evolved by i r detection (leco multiphase carbon analyser rc-412). besides organic material, the sediments also contain a minero genic carbon phase (coal), which is thermally stable u p t o temperatures of 450-500". to sep arate organic carbon (corg) from bedrock derived carbon present as coal (c,,,) the amount of minerogenic carbon was estimated after oxidation of separate samples with hzoz and h n 0 3 , which preferentially oxidises the organic matter. both carbon phases a r e reported as weight % c of the dry matter. t h e total sulphur content was determined o n subsamples from cores s t 3a. b & st 4 after digestion of the samples a t 450°c in a mixture of k n 0 3 and n a n 0 3 (50/50 molar %) followed by dissolution in a reagent solution of k n 0 3 / n a n 0 3 in hci (mcquaker & fung 1975). the sulphur content was then measured gravimetrically after hot precipitation of so4'as baso,. macroand microfossil analysis for macrofossil analyses, 5-15 cm thick samples from st 2 . s t 3a and st 4 were pre-treated with 10% n a o h and sieved through a 0.25 m m mesh. t h e macrofossils were sorted o u t under a bin ocular microscope. identifications were carried out by comparisons with modern reference material. t h e reconstruction of the thermal cli table 3 . lithostratigraphy of core st 3 8 at a water depth of 4.oom. the ilthostratigraphic descnption is based on the field description. where the different gyttja clay layers were mainly distinguished by colour differences. unit layer depth in m sediment descnption i 4 3 1 7 5 07 -5 45 5 4.5 -5 51 5 5 1 -5 52 5.52 -5.56 5 56 -5.65 5 . 6 5 -5.82 5 82 -5 935 5 935-5 97 5 97 4 00 6 0 0 4 0 7 black (fes-) coloured silty gyttja clay with brown-yellowish layers and some moss remains, glb reddish-brown silty gyttja clay. rich i n mosses, some fes laminae, slb black (fes-) silty gyttla clay. fairlv rich in mosses. g-slb reddish-brown and greenish silty clay. fes laminae in the upper part, slb reddish-grey sandy silty clay. very compact. slb grey silty sandy gravelly clay with small angular stones (3 cm 0). clay layer between 5.715-5.735. yellow-grey silty sandv gravel. with silty clay layers, glb reddish. sandy silty clay. compact, glb yellow-grey sandy silty gravelly clay. compact reddish to red-brown. sandy silty clay. compact glb early holocene environment on bj@rn@ya (svalbard) 261 mate was made by using the mutual climatic range method (mcr) on fossil coleoptera. this method is based on the present geographical ranges of the species in relation to modern tem perature (atkinson et al. 1986). the palaeo temperatures were reconstructed by use of the mutual intersection of the climatic ranges of selec ted stenothermic species in the fossil record. the mcr method reconstructs mean july (warmest month) temperature (tmax) and mean january (coldest month) temperature (tmin). one of the great advantages of the mcr method is that it is possible to test its accuracy on modern coleoptera assemblages in relation to climate. such studies have shown the need of a calibration of the mcr results to obtain the most probable palae otemperature (atkinson et al. 1987). this cali bration is carried out by using the correction equations: tmax~,,,,,,te,j) = 1.066 tmax(me,jian) + 0.0142 tmin~,o,,e,~,d) = 1.416 tmin(medi,n) -k 1.904 x no. of species x -2.96 the precision of the most probable palaeo temperature is ca 4 2°c for tmax and ca +. 5°c for tmin. in st 3a subsamples for pollen (including spores, pediastrum and bofryococcus) were spaced every 5 cm in the upper layers (layers 10 15) and every 2 cm in the basal layers (layers 6 9). the samples (2 cm3) were treated with znc12 and prepared according to conventional pro cedures. tablets with lycopodium spores were added to the pollen samples to determine con centration values. the group of betula pollen includes both tree and dwarf birch. subsamples for diatoms in core st 3a were prepared in accordance with the methods described by battarbee (1986). a m s 14c measurements to obtain datable material for ams measure ments subsamples from cores st 2, st 3a and st 4 were sieved through a 0.5 mm mesh and the macrofossils recovered were determined under a stereomicroscope. intact leaves of safix species were immediately dried on aluminium foil (at 50°c over night), stored in sterilised glass bottles and sent to the tandem laboratory in uppsala. a full pre-treatment (including 1% hci, 6 hrs at 80°c and 0.5% naoh, 1 hr at 60°c) was applied to the salix samples. the moss remains were submitted in distilled water and pretreated with 1 % hci (6 hrs at sot). t a b k 4. lithostratigrdphy of core st 4 at a water depth of 4.25111 the lithostratigraphic descrlption is based on the field description, where the different gyttja clay layers were mainly distinguished by colour differences. ~ unit layer depth in m sediment descnptton 18 5.20 -5.50 17 5.50 -5.74 16 5.74 -5.81 15/14 5.81 -5.865 13 5.865-5.98 12 5.98 -6.07 11 6.07 -6.49 9/10 6.49 -6.65 8 6.65 -6.70 7 6.70 -6.73 6~ 6.73 -6.17 6b 6.77 -6.785 6a 6.785-6.82 5 6.82 4 . 8 4 3 6.88 4 . 9 3 4 6.84 -6.88 2 6.93 -7.00 alternating layers of black and beige-brown coloured silty gyttja clay with moss remains, glb slightly fes coloured silty gyttja clay with moss remains; more fes laminae between 5.50-5.60. 5.60-5.64, 5.6b5.70, glb light-brown silty gyttja clay with moss remains and few fes spots, glb light-brown silty gyttja clay, at 5.845-5.85 and 5,865.865 yellow coloured layers. slb light brown silty gyttja clay. fes laminations only between 5.94-5.95, otherwise fes spots. moss remains, glb reddish-brown silty gyttja clay, mosses, fes spots, glb alternating layers of black (1-3 cm) and brown-reddish (0.5 cm) silty gyttja clay, glb alternating layers of black, greenish, brown-reddish silty gyttja clay, pebble at 6.565. glb black moss-rich silty gyttja clay, glb reddish-brown silty gyttja clay, fes spots and laminae, moss remains, glb reddish-brown clayey silt, few fes spots, g-slb greenish clayey silt separated by a brown-reddish clay layer (3 mm), slb reddish silty clay, very sharp lb greenish sandy gravelly clay, unregular lb reddish clayey sandy gravel. g-slb reddish-brown sandy silty clay, pebbles, slb greenish. yellow, reddish laminated sandy silty clay, pebbles, soft 262 b. woldfartli er a1 results lithostratigraphy. grain size and geochernistrv the lithostratigraphy of the sediments was described in the field where the fresh cores all showed very distinct black fes stains and horizons. which (with the exception of core s t 4) were found to have disappeared (due to oxida tion) when the cores were unwrapped in the laboratory. t h e lithostratigraphy presented in tables 1-4 mainly follows the field description. but has been verified in the laboratory. t h e dis tinction in different sediment layers (1-20) is based on sediment colour, grain size and organic content. however. because postdepositional chemical reactions are responsible for the colour differences of the sediment column, the litho stratigraphic sequence was divided into three units. unit i comprises layers 1-7. unit i1 layers 8-11 and unit 111 layers 12-20. t h e lowermost niinerogenic sediment layers of unit i were recovered in all four cores, but attain a maximum thickness of 55 cm in st 3b only. in this core the compact reddish-brown and yellow grey sediments between 6.07-5.935 m (layers 1 3) show a gradual transition from sandy silty clay to sandy gravelly silty clay and sandy silty clay (fig. 3, table 3 ) . between 5.935-5.82 m (layers 4-5). the sediments are compo3ed of loose sandy clayey gravel and sandy gravelly clay with small pebbles. a reddish-grek sandy silty clay (layer 6) and a silty clay with some fes stains (layer 7 ) follow with sharp lower boundaries (fig. 3. tables 1-4). the water content is constant (ca 20-30%) and reflects the dominance of the silt and sand fractions ( > 5 5 % ) in these bottom layers (fig. 4 ) . in the uppermost part of unit i . the water content increases slightly to 357r. the sand fraction decreases to 0% and the silt and clay fractions dominate the grain size distribution. t h e total carbon content (c,,,,) varies between 0.3 and 3.3%. coal particles (c,,,,”) derived from the bed rock are the dominant carbon source with between 0.4 and 3.1%. organic carbon (cur& contributes between 0.2 and 0.8%. the sulphur content is stable below 0.1% (fig. 4). the transition from unit i t o unit i1 is charac terised by a drastic change in colour and lithology from reddish-brown silty clay to black silty gyttja clay (fig. 3). i n cores s t 2 , 3a and 3b. the silty gyttja clays in the lower part of unit i1 are light brown. reddish-brown and brown-yellowish, whereas the corresponding layers in s t 4 show alternating black, greenish and brown-reddish laminae. t h e silty gyttja clay in the upper part of unit i1 is characterised in all four cores by alternating black and brown-reddish laminae (fig. 3, table 1-4). t h e lower boundaries of layers 9 and 10 appear sharp. layer 10 is only present in cores st 3 a and s t 4 and seems to be missing in s t 2 and s t 3b. t h e water content increases rapidly from 40% t o 60% at the tran sition from unit i t o unit i1 and attains 80% in the upper part of unit 11. t h e grain size distribution is dominated by clay and silt, which attain ca 50% each, apart from two excursions at 5.30-5.22 and at 5 . 1 0 m , where the sand fraction increases t o 10% and 5% respectively (fig. 4). t h e content in c,,, increases from 1.6% at the transition unit 1/11 to a maximum of 4.3% in the upper part of unit 11. this increase is entirely attributable to organic matter. parallel with the increase in corgr the sulphur values rise from 0.2% t o 1.8% and remain constant between 0.8 and 1.3% in unit 11. when comparing the curves for organic carbon and sulphur, it becomes obvious that high carbon values coincide with peaks in the sulphur content. t h e upper half of t h e stevatnet sequence, unit 111 (layers 12-20) comprises silty gyttja clays with colours varying from yellowish, light-brown, red dish-brown to black. t h e water content decreases slightly t o between 65-70%. but varies, especially in the upper part of unit i11 between 55-75%. t h e grain size distribution displays a dominance of the silt (ca 40%) and clay 50-60% fraction. in the upper part of unit 111, at 4 . 2 9 m , the clay fraction (<2p) decreases t o 20% and the silt fraction (<60 p) increases to 70%. t h e total car bon content displays in general a slightly decreas ing trend from 3.2% in the lower part of unit 111 to 2.5% in the top. corg remains the major fraction of the total carbon content. whereas minerogenic carbon is nearly constant a t ca 0.4-0.6%. t h e sulphur values show a similar gradual decrease from 0.95% to less than 0.2%. higher sulphur values a t 5 . 0 2 m ( l . l % ) , 4 . 9 4 m (1.2%) and between 4 . 1 0 4 . 2 0 m (0.4%) coincide with higher core values. miiieral magrietics a critical prerequisite for the correct environ mental interpretation of mineral magnetic inves tigations is the analysis of fresh samples (in this case prior to oxidation). t h e results obtained from core s t 4 a r e presented first as it was noted 4.00 4.20 4.40 4.60 4.80 e .c 5.00 2 a 5.20 % 5.40 5.60 5.80 6.00 4.00 4.20 4.40 4.60 4.80 5.00 5.20 5.40 5.60 5.80 6.00 early holocene environment on bj@rn#ya (svalbard) 263 stevatnet st3 a 8 3 b 0 20 40 60 80 0 50 100 water content in % grain size in % unit 4.00 4.20 4.40 4.60 4.80 5.00 5.20 5.40 5.60 5.80 6.00 4.00 4.20 4.40 4.60 4.80 5.00 5.20 5.40 5.60 5.80 6 00 0 1 2 3 4 5 0 1 2 total, minerogenic 8 organic carbon in % sulphur in % f i g . 4. water content, grain sizc, carbon and sulphur content of cores st 3a and 3b. the lithostratigraphy and the analyhes below 5.62 m are interpolated from core st 3b. that t h e well-wrapped sediments had not oxidised during storage and that the original fes stra tigraphy remained intact (see above). fig. 5 displays the mineral magnetic properties of bulk samples taken from core s t 4. x and s i r m a r e generally low in unit i , between a depth of 7.00 and 6.68m, and indicate a low concentration of magnetic minerals in the minerogenic sediments, while the high s-ratio indicates that antiferrimagnetic minerals (e.g. goethite/haematite) dominate the mineral mag netic properties. a distinct change occurs in the magnetic properties at the transition from unit i t o unit 11, at 6.68111, and the concentration of ferrimagnetic minerals (indicated by xand sirm) increases dramatically. t h e s-ratio decreases t o -0.8 and indicates that a “soft” magnetic mineral (e.g. magnetite/greigite) dominates the mineral magnetic assemblage u p to the top of the core. a p a r t from the lowermost sample at 6.68 m. only insignificant fluctuations occur in the magnetic parameters u p t o a depth of 5 . 8 0 m . in unit 11, between 5.80 and 5.50 m the concentration par ameters and the s-ratio fluctuate. although they return t o stable values in unit 111, between 5.50 and 5.23 m . t h e linear relationship between s i r m and x in the sediment above 6.68 m (fig. 6) indicates that only o n e ferrimagnetic mineral makes a significant contribution to the mineral magnetic assemblages in the sediments above 6.68 m . t h e thermomagnetic behaviour of a magnetic concentrate from a sediment depth of 6 . 6 8 m (with high ferrimagnetic concentration) is shown in fig. 7 a . t h e almost completely irreversible loss of magnetization between 300 and 400°c is typical of ferrimagnetic greigite when heated in air (snowball & thompson 1990). the sharp rise in magnetisation o n heating at 150°c is explained by the additional formation of greigite in the 264 b . wohlfarth et r i . t e f a a a * +++ 3 :+ ++; ++ ++ ++ ++ q ++t +$+: + { + 3 3+ 8' : + + + + + + ++ ++ + + $ 3 ++ b u l k susceptibility bulk sirm s r a t i o slrmlx ( 1 0 ' ~ s . i . units) ( r n a m " ) ( k a m ' ) 0.0 4.0 8.0 0 100 2 0 0 . l o o 0.00 1.00 0 4 0 80 5 00 j i + + 5 50 5 75 6 2 5 ++ 7 0 0 i i ~ i ++ i ++j++ + i+;+:++ + 1 +$ i?++ + i:+ + + * + + ++++,+ + i ++ + + * + f+ fig. 5 . mineral magnetic properties o f core st j 7*50 1 f l + .l sample (snowball 1991), produced from a phase transformation of unidentified iron sulphides associated with the ferrimagnetic concentrate. the curve shown is typical of those obtained from magnetic concentrates of sediments above 6.68 m and they demonstrate that the magnetic proper ties a r e dominated by greigite. t h e x-ray dif fraction analysis of the magnetic concentrate confirms the identification of the ferrimagnetic phase as greigite (fig. 7b). a magnetic hysteresis curve. representative of the magnetic concen trates is shown in fig. 7c. t h e very open central section is typical of natural greigite samples (snowball 1991) and the high mrs/ms ratio (0.56) + 0.00 i t , ' and low (bo)cr/(bo)c ratio (1.3) indicate that the 0 50 100 150 200 greigite is of a single-domain magnetic grain size. greigite of variable morphology (needles. plates, cubes etc.) formed by authigenesis at low tem peratures and pressures in sediments has normally been found to exhibit single-domain magnetic behaviour. bulk s l r m (rnarn') fig. 6. sirm y s magnetic susceptibility for the sediments above a dcpth of 6.68 m i n core st 4 . the linear relationship demon strates that onc mineral contributes to the magnetic assemhlagc. early holocene environment on bj#rn#ya (svalbard) 265 a 1.75 1.50 1 stevatnet 4 sample 17 extract b i i 0 100 200 300 400 500 600 700 temperature ("c) . , . . . . . . 55 5 0 45 4 0 35 30 25 20 2 8 c 0.50 -0.25 -0.50 -0.75 -1.00 -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 field (t) fig. 7. a . typical thermomagnetic curve of a magnetic con centrate. the curve indicates the presence of greigite and the absence of magnetite, b. xrd pattern of magnetic concentrate. greigite is the only ferrimagnetic mineral present. g = greigite, q = quartz, sh = sample holder. cuknradiation was applied. c. the hysteresis loop of a magnetic concentrate. the loop is characteristic of single-domain greigite grains. the more scattered nature of the sirm and s ratio curves in unit i11 of core st 4, between 5.80 and 5.50 m, is linked to the observed stratigraphy and is caused by the precipitation of greigite on the surfaces of relatively large moss remains. the discovery that greigite is responsible for the min eral magnetic characteristics of the sediment that lies above 6.68 m in core st 4 aids in the inter pretation of the sirm measurements carried out on the other cores. fig. 8 displays sirm values for all four cores. greigite is responsible for high values of sirm above the lowermost minerogenic sediments. although it is still possible to delimit the different stratigraphic layers in st 2, st 3a and 3b, based upon the mineral magnetic measurements, only the magnetic properties of st 4 can be considered representative of the fresh sediment. the postdepositional authigenic formation of ferrimagnetic greigite prevents the interpretation of the mineral magnetic results in terms of catchment erosion. however, specific geochemical conditions are required to promote greigite formation. greigite is a precursor to pyrite and may be preserved in sediment sequences when pyrite formation is limited by sulphur availability (berner 1981). the occur rence of greigite in the early holocene sediments indicates that anoxic conditions prevailed in the deeper regions of the basin following the onset of the deposition of organic material. the cor$st ratio is approximately 4 in unit i1 of st 3a (between 5.6 and 5.0m), but increases to ca 7 above 5.0 m and indicates that sulphur availability became a limiting factor in greigite authigenesis. the lower sirm values in unit i11 of core st 3a are due to the absence of greigite authigenesis, which indicates that the sedimentary environment altered between a depth of 5.0 and 4.8 m in core st 3a. microfossil analysis (pollen, spores, algae) pollen. the pollen diagram (fig. 9) covers the lower part of core st 3a. the total pollen sum ranges between 54-130 pollen/sample in the bot tom part, and increases to between 112-418 pollen/sample further up in the sequence. s p z 1 : artemisia-oxyria/rurnex-beth zone (5.62-5.52). this pollen zone, which comprises the two lowermost samples (below and above the transition from unit i to unit 11). is characterised by approximately equal proportions of herb and b e t h pollen. artemisia values attain 20% in the 266 b. wohlfarth et al st 2 st 3a st 36 st 4 slrm rnam2kg-l slrm marn%g” slrm mam%g bulk irm,~maj 0 0 0 1 0 0 0 2 0 0 0 0 0 0 1000 2 0 0 0 0 0 0 1 0 0 0 2000 0 0 0 1 0 0 0 0 2 0 0 0 0 4.80 5.20 5.40 5.60 5.80 6.00 6.20 6.40 6.60 6.80 7.00 + + i++:; 3: + + ~ tf + + $ + + 3 :+ ++ + + + ++ + * + +,t: + + + + + + + + 3 +++ 3 + + + + + + !+i?++ 4 a 3 + + + + erg k t h e s i r m of s r 2 st 3a b b and st 4 greigite i s responsible for the hqh values of sirm in all of the cores bottom sample, but decrease to 10% in the upper sample, whereas 0xvrialrutne.x frequencies increase to 30%. but show a slow decrease in the upper part of this zone (10%). s p z 2 : oxyria/rirtne.x-betula-piniis-zone (5.52-4.95 m). during this pollen zone. herb pol len values decrease gradually from 45 to 1055, while frequencies o f tree pollen increase from 5 5 t o 90%. oxyria/rime.x values decrease gradually from 30 to 5 % . salix and arternisia pollen fre quencies remain at ca 5 % . but decrease in the upper part t o ca 2.5%. jittiiperirs values increase aliphtly during the uppermost 2 0 c m . but do not attain more than 5 % . t h e lowermost local pollen zone spz 1 com pares well with hyviirinen‘s (1968. 1970) zone i . where he describes abundant non-arboreal pollen ( n a p ) with a dominance of betula among the tree pollen. t h e second local pollen zone spz 2 may be compared with zone iia in hyvarinen‘s (1968. 1970) diagrams, where lower nap values and a rise in a l n u s are reported. there is, however, a major difference between our diagram and the diagrams presented by hyvarinen (1968, 1970): pinus pollen values attain rarely more than 20% in o u r diagrams, but increase in hyvarinen’s (1968, 1970) zone i1 to more than 50%. this might be explained by the fact that we could have lost a major part of the pine pollen during the pollen preparation, where we applied a znc1, treatment to separate the pollen grains. o u r pollen spectrum is clearly dominated by long-distance transported pollen grains. all tree pollen (betula, pinus. alnus) and most of the non-arboreal pollen (arteniisia, chenopo diaceae. filipetidula, urtica. jitniperus, caryo phyllaceae) must be regarded as exotic. salix, gramineae. cyperaceae, oxyria/rume.r. rosa ceae might represent a mixture of local and long distance transported pollen. ranunculaceae, n d .. -~ . ........................ ro a od n n n 268 b . wohlfarih et al. ericaceae and sarifraga which occur in the recent flora ( e n g e l s k j ~ n 1986) may have grown o n the island. t h e dominance of long-distance trans ported tree pollen in t h e pollen spectrum is a typical feature in holocene pollen spectra from e.g. spitsbergen (hyvarinen 1970) or northern fennoscandia (e.g. hjelmroos & franzcn 1994). possible sources include areas adjacent to the barents sea but may b e as far south as south europe/north africa (hjelmroos & franzkn 1994). spores und algae. spores of polypodiaceae (undiff.) are present throughout the whole sequence with ca 5%. lasrrea dryopteris appears from ca 5.51 m upwards (fig. 9). it attains values of 1 0 8 at 5 . 1 s m . but decreases below 5% between 4.99-4.95 m . all spores are regarded as long transported. pediasrritm values increase very rapidly from less than 57c at 5 . 6 2 m to 10% at 5.60 m and to 5 0 8 at 5.56 m . in the upper part of the sequence pediastrum values a r e around 50 70%. boiryococcus decreasesfrom 1 0 7 ~ at 5.62 m to less than 5% at 5.55 m. it is not present between 5.52-5.40 m. but increases again from 5.40 m upwards. diafoms. diatoms are extremely rare in most of the analysed samples of core s t 3 a (table 5 ) . in unit 1 and in the lowermost part of unit i 1 only few, quite heavily corroded diatoms were found. however. higher u p in unit 11, the preservation was slightly better. t h e diatom assemblage is dominated by brachysira species and includes staiironeis anceps, fragilaria pinnata. amphora libyca. a m p h o r a cf. ueneta, which indicate fresh water conditions and a probably higher p h than table 5 . diatom taxa recorded in core st 3a that found in the top sample. between 5.50 4 . 5 0 m (units i1 and 111) the diatoms are again very badly preserved. although the species recovered at 4 . 5 0 m are also poorly preserved and dissolved, robust forms, such as fragilaria pinnata, frustulia sp. and pinnularia can be recog nised. fragilaria pinnata is fairly common in soft waters. only in the t o p sediment at 4.00 m , where fragilaria virescens var. exiguam becomes t h e dominating form, are the diatoms abundant and well preserved. all the species recorded a t 4.50 m are benthic forms and indicative of slightly acid (possibly around p h 5-6) and shallow waters. shallow water could explain the absence of centric forms. macrofossil analysis macroscopic remains of plants and animals were sorted o u t from cores s t 2, s t 3a and s t 4 (fig. 3). t h e results of the identification are shown in table 6. t h e following remarks o n the veg etational and faunal record is based o n the mod e r n biology and geographical distribution of the mentioned taxa (palm 1948; r ~ n n i n g 1979; eng e l s k j ~ n 1986; fitter & manuel 1986; hulten & fries 1986; nilsson & persson 1989; mossberg et al. 1992). in general, mosses and midges dominate the fossil assemblages and are present from the lower most analysed samples in unit i t o the uppermost sample in unit 111. mosses a r e especially frequent in the lower part of unit 11. leaf fragments of dwarf willows such as salix reticulata, s. herbaceae and s . polaris a r e recorded in units i1 and i11 (fig. 3 & table 6 ) . these species are today dominant or characteristic in plant communities on well depth ( m j 4 ckj 4.51) 5.00 5.37 5.54 5 59 5.61 5 6 2 5.66 unit 111 111 111 11 11 11 i i i ~~ diatom taxa (listed according to thcir frequency) fragrlaria uirescerrr var uxrgua. fragilarra consrrriens var ~ e n r e r . naoicula cocconeiformis. c y f n b c l l a guumanii. achrianrhes flexellu. n a ~ r c r i l a iirgirulro. pinrrlaria sp., frrisrulina rhornboides var saxonica. achnanrhes scotica fragilaria pinnara. frusrulia s p . . prnnulana sp. fe\r/no diatoms fewjno diatoms stouroneis anceps. fragilaria pinnara. a m p h o r a libyca. a m p h o r a cf. oeneru. bruchysira sp. diatoms are extremelv rare diatoms are extremely rare diatoms are extremely rare diatoms are extremely rare early holocene environment on b j ~ r n f l y a (svalbard) 269 drained and exposed ground in the inland of bj@m@ya. in two samples from the upper part of unit i1 (layer l l ) , rather corroded leaf remains of dryas sp. were found. this plant grows on calcareous soils in spitsbergen and scandinavia, but is not found on bjornqya. this species is probably absent because it requires higher sum mer temperatures than those presently encoun tered on the island (engelskjgn 1986). one fruit of angelica cf. archangelica is recorded in sample 30 of unit i1 (layer 11). today this species has a more southern distribution with its northern limit in northernmost norway. it grows on moist sandy or peaty soils. in willow shrubs, meadows and on river shores. three beetle species were identified among the insect remains (table 6). the diving beetle agabus bipustulatus is widespread in europe. in arctic and alpine regions its main habitat is shallow lakes with stony or silty bottoms. the rove beetles olophrum boreale and eucnecosum tenue are dis tributed in northernmost europe, where they are found in leaf litter of s a l k and betula. caddis fly larvae (trichoptera) of the family limnephilidae occur in all sorts of habitats, ranging from fast running streams to large lakes. midge larvae ( d i p tera, chironomidae) mainly live in the bottom sediments of lakes or ponds. the jaw of the notostracan crustacean lepidurus (tadpole shrimp) found in unit i1 (layer 11, sample 31) could not be identified to species level. however. lepidurus articus pallas is a common species today north of the arctic circle, where it lives either in temporary pools or at the edges of lakes (taylor & coope 1985). chronostratigraphy serious problems concerned with the radiocarbon dating of arctic sediments have been reported in previous studies (e.g. olsson 1986; bjorck et al. 1994a, b; abbott & stafford 1995; miller et al. table 6 . macroscopic remains of plants and animals from cores st 2 , 3 a and 4 . l = leaves, bs = budscales. f = fruit, ms = meta/ mesosternum. l e = left elytron. re = right elytron, th = thorax, h = head, mnd = jaw. relative abundance of remains are indicated as + = 1-10, + + = 11-100, + + + > 100. see fig. 3 for the location of the samples. taxon samples spermatophyta salicaceae salix reticulata l. salix herbacea l. salix polaris wahlenb. salix spp. dryas sp. angelica cf. archangelica l. rosaceae apiaceae bryophyta indet. insecta coleoptera dytiscidae staphylinidae agabus bipusfulatirs (l.) oiophrrrm boreale (payk.) eucnecosurn lenue (lec.) gen. indet. trichoptera limnephilidae indet. hymenoptera fam. indet. diptera chironomidae indet. notostraca lepidurus sp. 11 (ms) 8 (re), 10, 13 (le), 33 (th) 38 (re) 30 (ms) 23, 27, 38 (th) 10. 31 ( h ) 4 , 6 , 8 1 3 , 1 5 1 7 ( + i , 1 8 2 0 (++), 21 (+). 22-25 (++). 26, 27 (+), 2 8 , ~ ’ ) (++). 30 (+i. 31 (++). 32-40 (+) 31 (mnd) 270 b . u’ohlfnrfh e f a / . 1995). t h e major problem in coal-bearing regions is that bulk sediment dates give erroneous ages d u e to “old carbon” derived from bedrock (ols son 1968; bjiirck et al. 1994a). another source of error may be i4c-depleted organic carbon. which is stored in tundra environments and incorporated in the sediments at a later date ( a b b o t & stafford 1995). to obtain correct radiocarbon dates, which exclude these sources of error. we only chose carefully selected macrofossils for dating. t h e selected samples contained >2 rng dried material. t w o samples were composed of moss remains and t w o samples of leaves of snli.1sp. (table 7 ) . t h e four a m s measurements obtained enable us to date the beginning of the organic production in the lake at the transition from unit i to unit i1 and the uppermost part of unit i1 (fig. 3). to be able to compare o u r ams dates to the bulk radio carbon dates obtained earlier on bj0m0ya (hy varinen 1968.1070; olsson 1968). i t was necessary to transform them into a bulk sediment age. if the organic carbon content and the age of the macrofossils in the sediment are known. as in this case ( s e e table 7 and fig. 4 ) . the influence of old bedrock carbon on bulk sediments can be calculated with the formula: l j where a,,,, = the macrofossil abuli. = the bulk “c age a m s “c measurement x = the fraction c,,, of c,,, if this formul,i is applied to our dates (table 7 ) . the ams “c ages of the samples would result in bulk “c ages of between 16.955 and 10.130 b p in this example the contribution of 60-20% ot ”old carbon” causes age differences of between 7200 and 1800 radiocarbon years. the gradual decrease in the amount of minerogenic carbon in the younger sediments decreases the difference between the “true age” and the bulk age. t h r e e dates on sediment samples from vestre skinkevatnet (northern part of b j s r n ~ y a ) , obtained on the humic fraction (extracted with 1 % n a o h ) were published by hyvarinen (1968, 1970) and discussed by olsson (1968). the lower most date. ua-2031 with an age of 11,200 ? 500 i4c b p was obtained ca 10 cm below hyvarinen’s (1968) pollen zone transition 1/11. ua-2050 (in pollen zone iib) gave an age of 4600 + 120u/ 1ockl ’.‘c bp. however, ua-2049, ca 5 cm below the pollen zone transition i i / i i i , gave an older age of 6000 + 3100/-2200 i4c bp. in the case of sample ua-2031 additional wet combustion with h 2 0 1 and h n 0 3 resulted in an age of 8300 + 1400/-1200 “c b p (ua-2042). t h e non dissolved remains were dated at 8900 + 1200/ 1000 “c bp (ua-2064) (hyvarinen 1968; olsson 1968). olsson (1468) suggested that the dis crepancies between t h e different fractions of the bulk sediment were caused by coal particles. the large errors and the age inversion of the two younger samples (ua-2050, ua-2049) indicate that too little humus could have been extracted for a measurement (olsson 1968) which makes a comparison t o our a m s dates impossible. based on the assumption that our local pollen zone spz 1 (5.62-5.52 m ) in core s t 3 a (fig. 9 ) might be comparable to hyvarinen’s (1968) zone i. then o u r a m s ages of between ca 9800-9500 “c bp should correspond approximately t o hyva rinen‘s bulk age of 11,200 2 500 i4c bp (ua-2031). if this correlation holds true, one might draw the conclusion that the amount of “old carbon” present in sample ua-2031 is ca 15-2096 which tuhlr 7 . a m s ”(’ mca\uremcnts on plant m a c r o f o s d s from corcs st 2 and st 3 a thc ilniount of hcdrock carhon (c,,,,) has bcen calculated from the carhon \slur\ ( i f the correapondms i d y m for the calsulatlons of thc bulh ”c age b p , see formula in thc 1 c y i sample usight l.ih no corc hcforc. ’nflrr p r c ams “c c,,,,, bulh “c h!er nt). depth ( n i l t a x o n treatment ( m e ) y r \ b p ( ‘ t ) ape br l x l n l s u h ( l c a \ e \ l 2 58,’l 84 8340 z xs ‘0 10.130 47yy s o h (lea\ e , 1 2.71; 1 . e 8.140 t_ i 2 5 20 10.130 41.21 aryophyro indet. ,?j.27 y565 2 95 30 41-w 51 ? a 8 5 5 % e r v o p h u a indrt 18 3 97y5 ? y o 61 early holocene environment on bj@rn@yvn (sualbard) 271 would result in a “true age” of ca 9650 l4c bp. such a n age would then correspond to o u r age attribution for spz 1 . however, this approach is highly hypothetical, because (1) the dates were performed o n material from two different lakes and (2) we d o not know the minerogenic carbon content of the old samples. palaeoenvironmental synthesis before 9800 ‘‘c b p the highly minerogenic bottom layers (unit i) possess alternating coarseand fine-grained sedi ments with a high concentration of redeposited coal particles. the lithology of these diamictons reflects t h e erosion of the surrounding bedrock. t h e compactness and the low water content, especially of t h e lower part of unit i (layers 1-4), implies over-consolidation. w e suggest that these sediments were originally deposited as tills by a locally active glacier during the ice retreat (see also salvigsen & slettemark 1995). whereas the overlying sediments (layers 5-6) may originate from glaciofluvial/fluvial deposition. a s confirmed by the mineral magnetic analyses, the reddish-brown colour of t h e lowermost sedi ment is attributable to ferric oxides/oxyhy droxides, such as haematite and goethite, which a r e stable only in oxic environments (berner 1971, 1981). t h e fact that this sediment was almost devoid of easily metabolised organic matter prob ably explains why it remained oxic after deposi tion, and why the ferric oxides survived. few diatoms a r e found in this sediment which was probably deposited from a turbid water column, a n inhospitable environment for living organisms. oxic conditions after deposition may also have enhanced the corrosion and dissolution of t h e diatom valves. t h e decreasing grain size, as well as the decrease in minerogenic carbon in the upper part of unit i. indicate that the erosion slowly ceased, possibly d u e to gradually more stable soils, which allowed deposition of a silty clay (figs. 3 and 4). however. the transitions between the layers, and especially between layers 6 and 7, are sharp and may indicate active sediment resuspension and the formation of a subsequent hiatus. the pollen sample from layer 7 includes mainly long-trans ported pollen grains, but also suggests that salix was growing in the surroundings. algae of the type botryococcus, mosses and midges found in the sediments indicate that the biological pro duction in the lake had gradually started. oxic conditions may also have prevailed during the deposition of the upper part of unit i, which is corroborated by the mineral magnetic analysis and explains why only so few (corroded) diatoms a r e present in the sediment. 9800-9500 l4c bp t h e transition from the minerogenic sediments in unit i to the organic sediments in unit i1 involves a drastic increase in the sulphur content and coincides with an abrupt change of the colour from reddish-grey to black (figs. 3 and 4). the black sediment colour is derived from metastable sulphides of iron. in particular greigite (fe,s,), the formation of which represents an arrested stage in pyrite diagenesis (berner 1971, 1981). t h e microbial reduction of sulphate is a strictly anaerobic process, and the formation of greigite in sediments is intimately linked t o the diagenetic processes associated with organic matter decomposition and the formation of h2s. the bedrock of bj0rn0ya and the stevatnet catchment is rich in iron sulphides (e.g. pyrite) and iron oxides and is potentially a major source of both iron and sulphur. another important source of sulphate must b e sea spray, which is transported by winds over the island and deposited in the lakes. it seems therefore reasonable to assume that the availability of easily metabolised organic matter, rather than of sulphur or iron, was a limiting factor in the sulphide diagenesis. as a result, conditions which supported oxygen deple tion and associated sulphide formation did not develop until reactive organic compounds were added to the sediment through the onset of bio logical production. this development coincides with a n increase in the number of midges, moss remains and in pediastruin in the sediment. once the prerequisites were given, restricted exchange of oxygen d u e t o long seasons of ice-cover may have further enhanced the oxygen depletion in the basin. relatively harsh conditions and/or a high amount of clay in the water column may be t h e reason why diatoms are still rare in the sediments from this time period. the pollen record is dominated by long-trans ported tree pollen. salix, ranunculaceae, eri caceae and saxifraga pollen may be regarded as local. 272 b. wohlfcirtir et 01. 95004300 ijc b p the gradual increase in organic matter in the sediment during this period is probably d u e to a combination of enhanced production in the lake. development of pioneer plant communities and increased inwash of organic material from the surrounding catchment (see below). apart from midges. remains of coleoprerci. tri clzoptera and hyrnerioptern are found together with algae and mosses. the few diatoms present in the lower part of unit i1 indicate freshwater conditions and a slightly higher p h value than that which the top sample indicates. the low concentration of diatoms at 5.37 m could be related t o a high clay content in the water column. the pollen include long-distance transported tree and non-arboreal pollen. however. s&x. rosaceae . ericaceae , ranunculaceae and s o x i fragri may be regarded as local pollen producer\. the vegetation i n the close surroundings of the lake may have been composed of. among others. willow shrubs ( s a l i x reticirlatn. sci1i.y polnris) on well-drained grounds. of dryas plants o n cal careous soils and angelica cf. archangelicn. which g r o w 5 on moist sandy or peaty soils or in willow scrub areas. the climatic reconstruction using the mcr method is based on two beetle species. ,4gahir.s hipiistiilcrtiis and olopkritrn horeale recorded i n sample\ 1 0 and 11 of unit 11 (table 6 ) . the results indicate a probablc mean july temperature (tmax,,,,,) of 9.3 -t 2°c and a mean january temperature (tmin,,,,,) o f -12.3 t 5°c. a warmer climate during this time period than today is also suggested by the presence of the 5,ascular plants i h y c i s sp. and arrgelica cf. arcliangelico. which require higher summer temperatures than those prevailing on the island at present (engels k j s n 19%). t h e mck results from stevatnet sug gest t h u b 1-5°c higher mean july temperatures than present. the winters seem to have been slightl! colder than present on b j s r n s y a . with mean january temperatures 5 6 ° c lower than today a strong seaaonality. which implies more con tinental conditions during this period. may esplaiii some o f the changes in the lakeicatchmcnt ecosystem that are recorded in the lake sediments. the formation of the distinctly sulphide laminated sediment in the upper part of unit i1 is connected to cyclic. possibly seasonal alterations of the redox conditions. the fact that the laminations arc best preserved in core st4, which was collected from the deepest part of t h e lake, implies that bottom anoxia developed during seasonal stratification of the lake or during periods of long ice cover. furthermore, the preservation of these laminae suggests that bottom anoxia was severe enough to eliminate benthic animals, whose grazing and burrowing activities normally obliterate sediment structures. t h e increased summer temperatures must have enhanced thaw processes in the upper most soil layers which explains the episodes of increased supply of allochthonous material, both minerogenic and organic. 8.300 ’“c b p lo present t h e r e a r e no a m s “c dates available which would allow an age assignment for the silty gyttja clays in unit 111. we can only assume that the sediments were deposited between 8300 “c b p and the present. which indicates that the sedi mentation rate in general decreased considerably compared to the previous periods. during the deposition of the lower part of unit 111 rather calm conditions may have prevailed in the lake basin. followed by sporadic inwash of minero genic material. in the upper part of unit 111, a sudden drastic increase in grain size is accompanied by an increase in minerogenic and organic carbon and i n the sulphur values. increased in-wash of material from the sur rounding slopes by soil processes/active weathering/freeze-thaw processes might be an explanation for this phenomenon. chironomidae and limnephilidae are present among the limnic fauna, and shrubs of sdix refi citlrctci and salix herbacea grew in the lakes‘sur roundings. these plants are a preferred habitat for the two rove beetles olophrurn horeale and e i ~ c n e r o ~ i m tenue. long-transported tree pollen increase gradually and non-arboreal pollen show a slight decrease. t h e benthic diatoms which are abundant in the t o p sample indicate that the lake has become slightly acid (possibly around p h 5 6 ) . conclusions the interpretation of o u r data set is based on lithology. grain size. mineral magnetic measure mentb. geochemistry. microand macrofossil analyses and ams “c dates on plant macro fossils. this multi-disciplinary approach allows us early holocene environment on b j l r n l y a (svalbard) 273 4~ years bp 8000 8500 fig. 10. a palaeo environmental synthesis of the earlv holocene palaeoenvironment on bjmnbya based o n the stevatnet sequence. lake relabvely calm condibons increased inwash of minerogenic and organic material from the catchment seasonal anoxia in deeper parts high organic production organic production beginning of the organic production degla 10.000 catchment increased freeze/lhaw processeslincreased erosion pioneer vegetaeon with willow shrubs, dryas and angelica archangelica establishment of a pioneer vegetation and gradual stabilisation of the soils " iation temperature gradual temperature decrease increased seasonality mean july temperatures ca. 9'c and mean january temperatures ca. 1 2 ' ~ gradual temperature increase ............. " covered by local glaciers t o suggest a possible environmental scenario for the early holocene on bjornaya, summarised in fig. 10. immediately after large scale deglaciation and prior to ca 9800 "c bp, glacial sediments were deposited in the lake basin. t h e time period between 9800 and 9500 i4c bp is characterised by gradually more stable soils, avery sudden increase in limnic production, although long seasons of snow and ice cover may have restricted an exten sive development of the biological communities. the increase in limnic production coincides with the abrupt sea surface temperature rise of 2 3°c between ca 10,000 and 9500 i4c bp (hald & dokken 1995) which was caused by the replace ment of cold arctic waters with warm atlantic water in the western and southeastern barents sea (hald & vorren 1987; vorren et al. 1988). between ca 9500 and 8300 "c bp a more con tinental climate. with strong seasonal contrasts prevailed o n b j ~ r n o y a . the marked temperature increase, with mean july temperatures around +9"c, is possibly as much as 4-5°c higher than present and the mean january temperatures around 12°c may have been 5 6 ° c lower than present. t h e plant communities on svalbard show that high summer temperatures affect plant growth, mostly through the length of the snow free growing season (ronning 1969; engelskjon 1986; skye 1989). high summer temperatures on bjornoya between 9500 and 8300 14c bp were responsible for the development of a pioneer community including dryas and angelica archnn gelica. as a consequence of the strong seasonality, freeze/thaw erosional processes in the sur rounding soils must have been enhanced. this, in combination with the more extensive vegetation cover caused an increase in the deposition of allochthonous organic material in the lake. this increase, coupled with high autochthonous pro ductivity in the lake during the summer months. may have caused oxygen deficiency, particularly severe during seasonal stratification and periods of ice cover. rapid snow melt and a n influx of a large quantity of water into the lake during the spring months would have caused temporary de stratification and oxygenation of the sediments. this may explain why the lake experienced alter nating oxic and anoxic conditions, indicated by the fes laminated sediments and the precipitation of authigenic greigite (hilton 1990). between 8300 14c bp and the present the sedi mentation rate decreased considerably and apart from two periods which display an increased in wash of minerogenic and organic material. the lake basin experienced fairly calm sedimentation. anoxic conditions coincided with the increase in total carbon content. t h e lack of ''c dates makes it, however, impossible t o discuss these phases in more detail. the diatoms in the top sediment indicate that the lake has become more acid. o u r temperature estimates for the time period 274 b. wohlfarth et a1 between 9500-8300 “c bp compare well with other studies from around the kara. laptev and east siberian seas. where a climatic optimum is described between 10.000-8500 “c bp (verkulich et al. 1995) when arctic hunters seem to have migrated into these high altitudes (pitulko rc makeyev 1 y y 1 ) . higher temperatures than present for the early holocene are also recorded from several studies on svalbard. thermophilous marine m o l l u x s flourished e.g. between ca 9500 1000 “c b p (salvigsen et al. 1990. 1992) and the linnebreen glacier melted completely during this period (mangerud & svendsen 1990). tem perature estimates based on plant macrofossil studieh in w’est spitsbergen indicate that between ca 80011 and 4000 ’‘c bp the mean july tem perature was cil 2°c higher than today (birks 1991). which is slightly later than our “tem perature optimum”. compared t o our data this may suggest that temperature had already slightly decreased after 8000 ‘“c b p . and that the warmest period during the early holocene occurred around 9500 and 8300 “c bp. as recorded in the sediments recovered from stevatnet. this coincides well with calculations of the solar radi ation for the northern hemisphere which suggest that maximum holocene seasonality was reached at around yo00 “c bp. with summer insolation higher and winter insolation lower than today (kutzhach & webb 1993). this pattern matches our environmental reconstruction convincingly well. ~ ~ k t i i ~ i ~ l e i l ~ e ~ n e i i r ~ ~ o u r t h a n k go to the swedish polar secretariat a d the s o r u c g i a n polar in,titute for logistic and economic >upport of the held work. to the n o r w g i a n coastal g u a r d . \ \ h o arranged rhc tramport t o and from the island. to the stat1 at radio bloriioya. \\hose great hospitalit! com pcnsated tor all the loge! 2nd rain! da!5 during the field work. to the helicopter crew5 of the soru-egian “redningstjenc\ten“ f o r their hclp with the transport 01 thc fieldwork equipment and the epectacular flight5 w e r the i\land, to x bao ( l u n d ) tor the pollen prcparations and r h e sulphur analyses o n core st 3 8 . to c . p e t c n ( e d i n h u r r h l for mcasuring the thcrmomagnetic prupertic\. t i ) ,li -j c i ; i i l l . d ilund) and 1 1 . il!\arincn ( t l c l sinki) f o r their help in intcrpreting the pollen diagram :ind to s . bjorck ~c‘openhageii) .ind 0 bennike (copenhagen) s h o criticall! read the nianu\cript and suggccted man! \aluahle imprix c‘incntc. references ahhott. \ i b . & stattord. t \5 1495: radiocarbon reservoir .ice\ and carhon q c l i n g i n arctic ,ind high-elevation iakc ,)>tern. absrrucr. s e c o n d annual p a l e research mc>ering. l i t o m i l l e . washington. 4-6 february 1945. atkinson. t. c . . briffa. k . r . . coope, g . r . . joachim. j . m. gi perry. d w . 1986: climatic calibration of coleopteran data. p p . 851-858 in berglund. b. e . (ed.): handbook of holocene palaeoecology and paliirohvdrology . wiley , chi chester. atkinson. t. c.. briffa. k . k. & coope. g. r. 1987: seasonal temperatures in britain during the past 22.000 years. recon structed using beetle remains. nnrrcre 3.52. 587-5y2. battarhee. r . w . (1986): diatom analysis. pp. 527-570 in berglund. b . e . ( e d . ) : handbook ofholocene palaeoecology and palaeohydrologv. wiley, chichester. berner. r . a 1971: principles of chernical .sedirnt~ntology. hlcgraw-hill book company. 240 pp. berner. r. a . 1981: a new chemical classification of scdi mentar! environments. j. sadimenr. perrol. 5 1 . 359-365. birks. h . h 1991: holocene vegetational history and climatic change in west spitshergen-plant macrofossils from skardtjorna. an arctic lake. the holocene i f.7). 209-218 bjorck. s . . bennike. 0.. ingolfsson. i . . barnekow. l. & penney. d . n . 19942: lake boksehandsken’s earlie\t post glacial sediments and their palaeoenvironmental implication.;. jameson land. east greenland. boreu.\ 2 3 . 4 5 s 4 7 2 bjorck. s . . wohlfarth. b . . bennike. 0.. hjort, c . & persson. t . 1491h: revigon of thc early holocene lake sediment b a w d c h r o n o l o p and e \ e n t stratigraphy on hochstetter forland. n e greenland. boreas 73. 513-523. bondevik. s . mangerud. j . . ronnert. l . & salvigaen, 0. 1995: t h e postglacial sea-level history of edgenya and barentsaya. eastern svalhard. polar res. 1 4 ( 2 ) . 153-180. e h c r h e i . a . & solheim. a . 1983: t h e barcnts sea ice sheet a \rdimentological discussion. polar res. 1 n. 5 . . 23-42, e k e r h o i . a , . nyland-berg. m . . russwurm. 1.. & solheim. a . 1990: late weichselian ice recession in the central barents sea pp. 78%307 in bleil. u . 62 thiede. j . (eds): geological hisrury ofrhe polar oceans: arctic vrrsiis anrorcric. kluver academic publishers. netherlands. elverhoi. a . . andersen, e . . dokken. t.. hehheln. d.. spiel hagrn. k.. svendsen. j . i . . s0rllatc.n. m . . kmnes. a . . hald, m. & forsherg, c . f . 1995: t h e growth and decay of the late wcichselian ice sheet in western svalbard and adjacent areas based o n provenance studies of the marinc record. abstract in andrews. j . t . . austin. w . e. n . & bergsten. h . e ( e d s ) the lureglocral polaeoceano~rap/iy of rlie norrh arlunric murgina. edinhurgh. engelskjnn. t. 1986. eco-geographical relations of the bjorn o!a vascular flora. svalhard. polar res. 5 . 7s127. fitter. r . 8; manucl. r . 1986: ficm guidc ro / h e frrjiiwnter l i f e of briraiti und norrliwest europe. collins. london. 382 pp fleetwood. a , . pejler. b.. einsle. u. & arnemo. k. 1974: stiatigraphical and biological invectigation, of cimr bjmn n!a lakes norsk polnrinsr. r r s b o k 1972, 63-71. hald. m . & vorren. t . 0 . 1987: stable isotope stratigraphy and palaeoceanography during the last deglaciation on the continental shelf off troms. northern norway. pulaeo c r a f i u g r . 7 f h j . 583-599 hald. m . & dokken. t. 1995: k’alaeoceanography on the euro pean arctic margin during the last deglaciation. ahstract in andrews. j t . . austin. w . e . n . & bergsten. h . e . (eds) the lareglucid palaeoceanogriiphy of rhe norrli a tlanric markim edinhurgh hilton. j 1990: greigite and the magnetic propertie\ of scdi ments lhnnol. and ocaanogr.. 35. 509-520. hjelmroos. m. & franzen. l. g . 1994: lmplicationi ot recent early holocene environment o n bjqrnoya (svalbard) 275 long-distance pollen transport events for the interpretation of fossil pollen records in fennoscandia. reuiew of palaeobot. pal.ynol. 8 2 , 175-189. hjort. c.. mangerud, j . , andrielsen, l., bondevik, j . y . & salvigsen, 0. 1995: radiocarbon dated common mussels mytilw edulis from eastern svalbard and the holocene cli matic optimum. polar res. 14(2), 239-243. horn, g. & orvin, a . k. 1928: geology of bear island. skr. sualb. og ishau. 15, 1-152, 9 pl., 1 geol map. h u l t h , e. & fries. m. 1986: atlas of north european vascular plants, vol 1-111. koeltz scientific books, konigstein. 1172 pp. hyvarincn, h. 1968: latequaternary sediment cores from lakes on bj@rnoya. geogr. a n n sua. 235-245 hyvarinen. h. 1970: flandrian pollen diagrams from svalbard. geogr. a n n . 52a. 213-222. kutzbach. j . e . & webb 111, t. 1993: conceptual basis for understanding late-quaternary climates. pp. 5-1 1 in wright, h . e . , kutzbach. j . e., webb 111, t., ruddiman, w. f., street-perrott. f. a . & bartlein, p. j . (eds): global climates since the last glacial maximum. university of minnesota press, minneapolis. keilhau, b. m. 1831: reise i @stog vest-hnmarken samf ril beeren-eilarid og spitsbergen. i aarene 1827 og 1828. christiania. 247 pp., 1 map, 3 pl. (facsimile borsums forlag, oslo 1973). mangerud. j . & svendsen, j . 1 . 1990: deglaciation chronology inferred from marine sediments in a proglacial lake basin, western spitsbergen. svalbard. boreas 19, 249-272. mcquaker, n . r . & fung, t. 1975: determination of total sulfur and total phosphorous in soils using fusion with alkali metal nitrates. anal. chem. 47, 1462-1464. miller, g. h . , stafford. t. w. & sauer, p. e. 1995: radiocarbon dating arctic lake sediments. abstract, second annual pale research meeting. eatonville, washington, 4-6 february 1995. mossberg, b.. stenberg, l. & ericsson. s . 1992: den nordiska flora.. wahlstrom & widstrand, stockholm. 696 pp. nilsson. a . n. & p e r s o n , s . 1989: the distribution of pre daceous diving beetles (coleoptera: noteridae, dytiscidae) in sweden. enrotnol. basiliensia 13, 59-146. olsson, i. 1968: radiocarbon analyses of lake sediment samples from bjbrt10ya. geogr. a n n . , m a , 246247. olsson, i. 1986: radiometric dating. pp. 27s312, in berglund, b. e. (ed.): handbook of holocene palaeoecology and palaeohydrology. wiley, chichester. palm. t. 1948: skalbaggar. coleoptera. kortvingar, fam. staphylinidae underfam. micropeplinae. phloeocharinae, olisthaerinae, proteininae, omaliinae. suerrsk lnsekffauna 9, 1-133. pitulko, v. v. & makeyev, v. m. 1991: ancient arctic hunters. nature 349, 349. ronning, 0. i . 1969: features of the ecology of some arctic svalbard (spitsbergen) plant communities. arct. alp. res. i , 29-44. ronning. 0. i . 1979: soalbards flora. polarhindbok n r . 1 . norsk polarinstitutt, oslo. 128 pp. salvigsen, 0. 1981: radiocarbon dated raised beaches in kong karls land, svalbard, and their consequences for the glacial history of the barents sea area. geogr. ann. 6 3 a . 283-291. salvigsen. 0. & slettemark, 0. 1995: post glaciation and sea levels on b j o r n ~ y a . svalbard. polar research 14(2), 245 251. salvigsen, 0.. elgersma. a., hjort, c . , lagerlund. e . , liestel, 0. & svensson. n:o. 1990: glacial history and shoreline displacement of erdmannflya and bohemanflya, spitshcrgen. svalbard. polar res. 8 , 261-273. salvigsen. 0.. forman, s . l. & miller, g . h . 1992: therm ophilous molluscs on svalbard during the holocene and their paleoclimatic implications. polar res. 11(1). 1-10. skye, e . 1989: changes to the climate and flora of hopen island during the last 110 years. arctic 42, 32s332 steffensen, e . 1969: the climate and its recent variations at the norwegian arctic stations. meteorol. ann 5(8j. 347 pp. steffensen, e. 1982: the climate at norwegian arctic stations. det norske meterologiske institutt. kiima 5 . 3-44. snowball, i . 1991: magnetic hysteresis properties of greigite (fe,s4) and a new occurrence in holocene sediments from swedish lappland. phys. earth planet. inter. 6 8 , 32-40 snowball. i . & thompson, r . 1990: a stable chcmical rem anence in holocene sediments. j. geophys. res. 95, 4471 4479. stein, r . , nam. s . , schubert, c., vogt. c . . futterer, d. & heinemeier. j . 1994: the last deglaciation event in the eastern central arctic ocean. science 264, 692-696. stober, j . c. & thompson, r . 1979: palaeomagnetic secular variation studies of finnish lake sediments and the carriers of remanence. earth planet. sci. lett. 37. 139-149. taylor, b. j . & coope, g . r. 1985: arthropods in the quat ernary of east anglia their role as indices of local palaeo environments and regional palaeoclimates. mod. geol. 9, 159-185. verkulich, s . r . . bol'shiyanov, d. y . . makeyev, v . m. & anisimov, m. a. 1995: investigations of the lakes and estu aries of the arctic in the framework of palaeogeographical studies of the aari. abstract, second annual pale research meeting. eatonville, washington. 4-6 february 1995. vorren, t. 0. 1992: glaciations of the barents sea an nvc'r view. soeriges geol. undersok. ca 8 1 . 367-371. vorren, t . 0.. hald, m. & lebesbye. e . 1988: late cenozoic environments i n the barents sea. palaeoceanogr. 3(5). 601 612. worsley, d. & edwards, m. b. 1976: the upper palaeoznic succession of bjorn0ya. norsk polarinst. h b o k 1971. 17-34. palynodebris analysis of a shallow core from the barents sea torbjbrn throndsen a n d t o r b j e r k e throndsen, t . & bjierke, t . 1983: palynodebris analysis of a shallow core from the barents sea. polar research 1 n.s., 43-47. oslo. a quantitative study of palynomorphs and palynodebris in a shallow core from the central part of bjbrn0yrenna. western barents sea, is presented. the core could be subdivided into a lower part characterized by a complete dominance of reworked plant debris of mesozoic age and an upper part with considerable input of first cycle algal debris and dinoflagellate cysts. two hypotheses are suggested to explain this radical change in palynodebris composition. either it represents a transition from a situation with permanent ice to normal marine conditions, or the absence of first cycle plant debris in the lower part of the core is caused by a masking of this component due to extremely high input of glacially eroded material from the bordering shallow parts of the barents sea. the present study shows that palynodebris analysis may contribute important information to the study of composition and depositional environment of quaternary marine sediments in the area. torbjmrn throndsen, saga petroleum a.s., p . o . box 9 , 1322 hgoik, norway; tor b j m k e , l a p , pb118, 3290 staoern, norway. march 1982 (revised january 1983). introduction during the 1970s norsk polarinstitutt and olje direktoratet carried out extensive sampling of unconsolidated sediments from the barents sea. gravity cores from the deeper parts of b j ~ r n oyrenna penetrated two characteristic lithologi cal units in the upper 2 to 3 m of the bottom sediment: an upper fine-grained, olive-grey soft mud 20 to loocm thick and a lower blue-grey mud. dropstones are present in both units, but most common in the lower unit. detailed sedi mentological and micropalaeontological studies have been carried out on this material during recent years (see e l v e r h ~ i & solheim 1983). in order to test the potential of palynodebris analysis and palynology for interpretation of the sedi mentation history in this type of environment, a detailed study was carried out on one of these cores. (palynodebris is defined as the total solid organic matter remaining after hcland hf treatment of a sediment sample; this definition extends the use of the term compared with that applied by manum 1976.) the core selected for study is located in the eastern part of bj0rnbyrenna at a water depth of 400 rn. the core reached 1.9 m and was sampled every 10 cm (fig. 1). by removing the outer sur face before sampling, care was taken to avoid contamination from other parts of the core. standard palynological preparation techniques were applied. both total palynodebris (unscreen ed) and screened residues (20 micron net) were studied in strew mounts. pal ynolog y palynomorphs were grouped into three different categories: dinocysts, bisaccate pollen, spores, and pollen other than bisaccates. based on pres ervation and colouration, each of these categories could easily be separated into first cycle and reworked palynomorphs. in addition acid resist ant inner linings of foraminifera were recorded, probably of first cycle origin. the relative amount of each of the categories was obtained by counting 200 to 300 specimens from each sample in screened residues. the results are shown in fig. 2 . below 1.00m nearly all palynomorphs are reworked from older sediments; only a few first cycle dinocysts were recorded from this interval. spores and pollen (s,) account for 60 to 80%, while bisaccates (b1) and dinocysts (dj each make up 10 to 20% of the total assemblage. at 0.85 m first cycle bisaccates (b2), spores and pollen (sz), and foraminifera (f) make their first appearance. foraminifera make up about 10% of the total assemblage, and first cycle bisaccates 43 44 t . throndren & t . bjrerke 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 [ 3 0 1 t v e grey m u d blue g r e y mud w i t h scoltered pebbles sample positions and spores and pollen 5 % or less throughout the upper part of the core. between 0.65 and 0.45m a rapid change in assemblage composition takes place by an increase in first cycle dinocysts (dl). at 0.45m they make up more than 50% of the total assem blage and above this level vary between 50 and 70%. in this part of the core, reworked spores and pollen (s1) are reduced to 10 to 3 0 % , while reworked bisaccates (b1) and dinocysts (di) each make up 10% or less of the total assemblage. among the reworked palynomorphs a few dinocysts could be identified. the presence of cribroperidinium sp., odontochitina s p . , cyclo nephelium eisenackii, pseudoceratium cf. regiutn, cyclonephelium distincturn, cf. paleoperidinium cretaceum, dejlandrea sp. and spores of the cicatricorisporites-type show that cretaceous sediments are the main source. a few specimens of upper triassic palynomorphs belonging to kyrtomisporis speciosus, zebrasporites interscrip tus and cf. protodiploxypinus sp. were also observed. they are characteristic of the upper fig. i. location and lith ology of studied core (bgr 1677-1 8). triassic part of the wilhelm~ya formation now exposed on hopen and probably on spitsbergen banken just west of hopen (bjzrke 1979). the dominance of first cycle dinocysts in the upper 0.50 m of the core is due to a single species, operculodinium centrocarpum. rare specimens of the genera spiniferites and nematosphaeropsis were also observed. first cycle pollen are rare, only a few specimens belonging to betula and pinus were observed. palynodebris when dealing with palynodebris comprising var iably degraded and corroded fragments due to heterogeneous origin, four categories are usually distinguished in transmitted light. bujak et al. (1977) defined the four groups as: amorphogen: unorganized, structureless organic debris which may be finely disseminated or cohering into fluffy masses. palynodebris in the barents sea 45 0.50. e i -c 0. u l 0 1.00 1.50 fig. 2. palynomorph distri bution in core (bgr 1 6 77-18). d i n o c y i t s d,-reworked d,i.cycle spores/ pol ian f 8 ' i t o t a l 1.cycle reworked i 2 0 4 0 00 8 0 % phyrogen: all non-opaque, recognizable plant matter that is not of wood origin including plant cuticles, palynomorphs, resin bodies and acid resistant inner linings of foraminifera. also trans lucent particles fragmented or degraded beyond identification are included. in the present study first cycle (p2) and reworked (pi) phyrogen are distinguished on the basis of colouration. first cycle phyrogen has a freshly green to pale yellow colour, while reworked phyrogen is deep yellow or brown. hylogen: translucent fragments of woody origin. fragments with a red-orange translucency along margins or other thinned areas but otherwise opaque are also included. melanogen: opaque organic matter typically com prising angular, fissured fragments, sometimes with cellular structures. the quantity of amorphogen relative to the other palynodebris components was visually estimated from strew mounts of the total assemblage (unsieved residue). the relative amounts of the other particulate palynodebris categories were obtained from counts of 150 to 400 fragments in strew mounts of screened resi dues. the results are shown in fig. 3. amorphogen (a) dominates in all samples. both finely disseminated and coherent amorpho gen is present throughout, but coherent masses are more common in the upper part of the core. the dominance of amorphogen suggests sedi mentation in a low energy environment (bujak et al. 1977; manum & throndsen 1978). 46 0.50 e f n m n 1.00. 1.50. t . throndsen & t . b j m k e p a l y n o d e b r i s i 1 . c y c l e phyrogen (p2) fig 3 palynodebr~s distribution in core (bgr 1677-18) phyrogen makes up slightly more than 50% of the particulate palynodebris (amorphogen excluded). below 0.65m there is a strong and consistent dominance of reworked phyrogen (p.). from 0.55 m upwards there is an increased input of first cycle phyrogen (pz). this is mainly due to an increase in marine dinocysts. first cycle phy rogen of terrestrial origin is rare. and first cycle cuticles are absent. a similar trend is also seen when comparing the relative abundance of first cycle phyrogen (p2) with hylogen (h) and melan ogen (m). o n the other hand, reworked phyrogen (pi) relative to hylogen and melanogen does not show this trend. this indicates that there was no . m m e l a n o g e n (m) 5 h m i p 2 h m 10 40 60 8 0 ;c 10 4 0 b0 80 a deposition of first cycle plant material of terres trial origin except for rare pollen and spores. conclusions in the core studied here amorphogen dominates throughout showing that deposition took place in a low energy environment. only traces of first cycle terrestrially derived material have been recorded. this means that there has been no input of sediment material from a land area covered by vegetation. the most likely sediment source is mesozoic rocks being eroded in more shallow palynodebris in the barents sea 47 parts of the barents sea. the reworked palyno morphs identified in the material show that the eroded sediments are mainly of cretaceous age. the input of reworked plant debris is considerable throughout. a comparison with the results of a regional study of rock fragments from the barents sea makes a northern to northeastern source area most likely (cp. bjzerke 1979). b j ~ r l y k k e et al. (1978) discussed the mineralogical and geochem ical composition of quaternary clays from the barents sea and concluded that it was controlled by reworking of mesozoic sediments. this obser vation is supported by our results. the subdivision of the core section into two units, an upper olive grey and a lower blue-grey mud, is clearly related to the palynomorph and palynodebris assemblages. in the lower unit, below 1.00 m, reworked palynomorphs make up nearly 100% of the total assemblage, and reworked phyrogen shows a strong dominance over first cycle phyrogen. this lack of first cycle plant debris and palynomorphs in the lower unit may be explained either by a permanent cover of floating ice during deposition or by an extensive masking of the first cycle material due to extremely high input of fine grained reworked material from glacially eroded areas. in the upper unit, above 1.00, there is a rapidly increasing input of first cycle plant debris mainly due to marine dinocysts and amorphous algal debris resulting in the olive-grey colour of this part of the core section. this abundance of dinocysts and algal debris shows that open, normal marine con ditions were established during the deposition of this unit. acknowledgements. we thank anders elverhdi for making the material available and for providing information regarding sampling and lithostratigraphy, and barrie dale for helpful discussions and identification of quaternary dinocysts. financial support from the norwegian council for scientific and industrial research (ntnf) is acknowledged. references bjsrke, t. 1979: geology of the barents sea shelf; evidence from palynological studies of drift material. norwegian sea symposium (nss) 17-1-15, norwegian petroleum soc. 1979. bj~irlykke, k . , bue, b . & elverhqi, a . 1978: quaternary sedi ments in the northwestern part of the barents sea and their relation t o the underlying mesozoic bedrock. sedimentology bujak, j . p., baras, m . s . & williams, g . l . 1977: offshore east canadas organic type and color and hydrocarbon poten tial. part i oil and gas j . 75(14), 198-202; partiilbid 75(15), 9 6 1 0 0 . e l v e r h ~ i . a. & solheim, a . 1983: the barents sea ice sheet a sedimentological discussion. polar research 1 n . s . . (this volume). manum, s. b. 1976: dinocysts in tertiary norwegian-green land sea sediments (deep sea drilling project leg 38). with observations on palynomorphs and palynodebris in relation to environment. pp. 897-919 in talwani, m., udintsew, g. et al. initial reports of the deep sea drilling project xxxviii: 29. (chapter 29). manum, s. b. & throndsen, t . 1978: dispersed organic matter (kerogen) in the spitsbergen tertiary. norsk. pdarinrt. arbok 1977. 179-187. 25(2), 227-246. christensen.indd 109christensen & falk 2001: polar research 20(1), 109–114 status of the common eider breeding in the municipality of avanersuaq (thule), north-west greenland kim diget christensen & knud falk late in the summers of 1997 and 1998 surveys of common eider (somateria mollissima) colonies were conducted throughout avanersuaq municipality in north-west greenland. although old information from eider colonies was available, these surveys provided the first thorough census of almost all colonies in the district, thereby improving the baseline data for assessing future population changes. the surveys were based on nest counts, and all but two colonies in the district were counted. in total, 3800 nests were counted, and an educated guess for the total common eider population in avanersuaq municipality, including the two inaccessible colonies, would be around 5000 pairs. average clutch size was 3.74, similar to or higher than in other areas of greenland and high arctic canada, suggesting favourable conditions for eiders in the survey area. comparison with older data suggests that the breeding population in avanersuaq is stable. this observation contrasts with the declines observed in other parts of greenland. further studies into possible population-specific migration routes and wintering areas as well as the direct and indirect effects of the intensive winter hunting in south-west greenland are warranted. k. d. christensen & k. falk, ornis consult ltd., vesterbrogade 140a, 2, dk-1620 copenhagen v, denmark; k. falk currently at danish polar center, strandgade 100h, dk-1401 copenhagen k, denmark. in the arctic, hunting still provides a significant portion of the food for a household. in particular, seabird species are harvested widely, often causing national and international management concerns (caff 1996, 1997). in greenland, considerable effort has been put into surveying breeding populations of the most important seabird quarry, the thick-billed murre (uria lomvia) (kampp et al. 1994; falk & kampp 1997), while little is known of the current status of the second most hunted species, the common eider (somateria mollissima). approximately 80 000 common eiders are reported to be shot annually in greenland, while the real figure might be much higher (frich 1997). available information suggests that a considerable proportion of the harvested population is wintering birds that breed in canada (nunavut), but due to lack of data, the relative contribution of birds from colonies in greenland cannot be assessed. the breeding eider population in west greenland has been reduced considerably during the 20th century (salomonsen 1967), and although only a few recent surveys have been conducted, the downward trend appears to continue in the most populated areas of west greenland (boertmann et al. 1996). a substantial breeding population decline has recently been found in an research note 110 status of the common eider in avanersuaq, north-west greenland area with low human population density in west greenland (frich et al. 1997). evidence of declining eider populations (common and king eiders [s. spectabilis]) have also been reported from arctic canada (cooch 1986; reed & erskine 1986; dickson 1997; robertson & gilchrist 1998). the high hunting toll in certain areas, combined with the scant information on population status, has led managers to call for intensified surveys and improved population monitoring of eiders in the arctic (caff 1997). although not known for certain, it is highly unlikely that the southern parts of west greenland—where most people live—should hold large, undiscovered eider colonies. however, according to existing information collated in the greenland seabird colony database (dmu-am & oc 1999), thinly populated north-west greenland might hold large colonies. therefore, field surveys were conducted in the avanersuaq (thule) municipality in 1997 and 1998 to provide up-to-date information on the status of the common eider for use in resource management initiatives (caff 1997), and for establishing a basis for future population monitoring. materials and methods survey area all available data on colonial seabird populations in greenland are compiled in the greenland seabird colony database, which was used to localize existing eider colonies between 76º and 79º n in the avanersuaq municipality, north-west greenland. a total of 14 eider colonies, all of which were on small groups of islands, were registered in the database for that region. in addition, detailed maps and aerial photographs were studied to identify other small islands that could be potential breeding sites for eiders. compared to other parts of greenland, the survey area had only few small islands, and no archipelagos, so the potential breeding sites for eiders are limited. this made surveys relatively straightforward, except for logistical constraints imposed by weather, ice and the distances involved. by means of outboard powered boats we attempted to visit all known colonies and potential sites late in, or just after, the incubation period. in the survey area, sea ice breaks up only a few weeks before the eiders leave the colonies, providing only a narrow time window to reach the colonies by boat. therefore, it was necessary to split the survey between two years. in 1997 (12–27 august) the effort was concentrated on the northernmost area, and in 1998 (29 july–19 august) the southernmost colonies were surveyed. even so, the northernmost sites were inaccessible due to heavy drift ice in the 1997 survey period. survey methods the survey was based on counts of nests. on small islands one or two observers counted all nests. to avoid double counting, each nest was marked with a piece of sugar (to dissolve with the next rain). on the bigger islands, flat areas with some vegetation were searched thoroughly; while steep slopes and areas devoid of vegetation were also searched since they were found to contain a few scattered nests. in one case, a relatively large island (in three sister bees group) with many scattered nests, the survey was based on line transects. the nests were counted on two approximately 370 m transects starting on the lower north-western part and ending on the higher (15 m) south-eastern part of the island; these fig. 1. map of the known and surveyed sites in the avanersuaq area, north-west greenland (see numbers in table 1); white areas on land indicate ice cap and glaciers. 111christensen & falk 2001: polar research 20(1), 109–114 transects were located within the area with eider nests (approximately 50 % of the island). when a nest was found, the perpendicular distance from the transect to the nest was measured. the number of nests/hectare was estimated employing the pc software “distance” (laake et al. 1993) using the half normal model. common eiders make a depression in the ground for their nest, which is first lined with plant materials and then with down (cramp 1977). many nests are reused, leading to formation of a depression that probably remains for many years under high arctic climatic conditions, with little rain and frozen ground most of the year. in some parts of the area local inhabitants collect eider down after the birds leave their nests. during the survey, many of the nests were found empty of down due to the collection, but still with quite fresh plant material in the bottom. hence, in the survey we distinguished between: i) nests with eggs and/or young; ii) nests with down; iii) nests with fresh plant material; and iv) old nest cups. in the third category it is possible that new plant material could have been deposited by birds which were merely prospecting for nest sites. but since we only found category iii nests on islands, where we knew down collection had taken place, we assumed that these nests had been used within the breeding season. the first three categories were therefore considered as representing breeding pairs while the latter category was excluded. for nests with eggs, the clutch size was noted. results in avanersuaq municipality, 12 of the 14 known sites were surveyed in the two years. some sites comprised several islands, so the total number of islands surveyed added up to 21 (in the database, it is not consistent whether groups of islands are pooled into one record, or data from each island recorded separately). the two northernmost known sites could not be reached because of sea ice. the location of all colonies is shown in fig. 1, and the number of nests counted in each colony site name no. of islands no. of islands survey year no. of pairs comments from older sources code a surveyed with eiders present 78001 pikulleq 0 ? • “large colony” (1936)b (macgary/eider islands) • 5000 eggs taken annually (sites 78001 + 78002) (1980s)c • <2500 eggs taken annually (sites 78001 + 78002) (1980s)d 78002 knorr islands 0 ? • “large colony” (1936)b • see also comments above 78003 sutherland island 1 0 1997 0 • “large colony” (1936)b 77002 hakluyt island 1 1 1997-98 9 no comments (new site, this study) 76016 qeqertaaraq 1 1 1997 105 • 50 66 (1987)e 76002-6 booth sound 7 5 1997 866 • 220 (1968)f (several islands) 76022 three sisters bees 3 3 1998 349 • “large colony” (1936)b • “colony” (1988)c 76001 manson islands 4 3 1998 652 • 100 (1985)g 76019 igannaq 1 1 1998 255 • 400 (1988)h (dalrymple rock) 76021 qeqertaarsuit 1 1 1998 1572 • “large colony” (1936)b (ederfugleøer) • 1000 (1988)h 76018 nuulliarsuit 1 1 1998 24 no comments (new site, this study 76031 igannaq 1 0 1998 0 • “large colony” (1936)b (conical rock) total 21 16 3832 a colony code according to the greenland seabird colony database (dmu-am & oc 1999) b salomonsen (1950) c a. rosing-asvid (pers. comm.) d born (1987) e k. kampp (pers. comm.) f salomonsen (unpubl. notes) g l. wellander in vaughan (1988) h m. kofoed (pers. comm.) table 1. results of a common eider colony survey in avanersuaq (thule) municipality, north-west greenland, 1997-98. 112 status of the common eider in avanersuaq, north-west greenland colony (or group of islands) summarized in table 1. the 16 islands with evidence of breeding common eiders contained a total of about 3800 nests (table 1). three new breeding sites were identified: in the manson islands group (no. 76001 in table 1) a small islet with 522 nests was found; a new colony (76018) with 24 nests was found near thule air base (pituffik); and on the large hakluyt island (77002) a few scattered nests were found. at two of the “known” sites no nests were found. according to local hunters, eiders breed on sutherland island in some years, but the only apparently suitable nesting area we found contained only a single possible old nest cup, so the island cannot hold a major colony. on igannaq (76031), there was no suitable eider nesting habitat, so it seems unlikely that there has ever been an eider colony here; the site has probably been included in the database due to the observer’s confusion with another island of a similar name. the largest colonies were usually found in areas with vegetation on small (2 5 ha), low-lying islands; this was the case at the booth sound islands, qeqertaarsuit, manson islands (522 of the 652 nests on a small island), and three sisters bees (341 of the 349 nests on a small island). on three sisters bees, the estimate of 341 pairs was based on counts of 46 nests using the line transect method. the larger islands (> 100 ha) usually only held relatively few nests, such as on igannaq and in the manson islands (107 nests of 652). on the larger islands the eiders avoided steep bare areas and seemed to concentrate in areas with vegetation close to the shore. most of the nests were found empty because the survey was conducted late in the season. in 1997, 59 % of the nests contained young, eggs or down and 41 % contained only plant material, but down collection had taken place on the island and therefore the nests with only plant material were assumed to represent breeding pairs. in 1998, none of the nests contained only plant material- all nests contained young, eggs or down. this was probably because the 1998 survey was conducted earlier in the season, before down had been collected. in the manson islands, the average clutch size was 3.74 (s.d. = 1.53) among 239 nests with eggs. in three cases, the eiders were found nesting close to other bird species, potentially assisting in fending off mammalian predators such as the arctic fox (alopex lagopus). in the manson islands, eiders nested near greater snow geese (anser c. caerulescens), a species that has been expanding its range in the avanersuaq area in recent years (boertmann 1994); on three sister bees, arctic terns (sterna paradisaea) aggressively protected the main breeding island, and on hakluyt island the few eider nests were found near a colony of glaucous gulls (larus hyperboreus). discussion the survey included all but two of the known breeding sites for common eiders in the avanersuaq municipality, and revealed a total population of at least 3800 pairs. apart from the two northernmost colonies (see below), the coverage was fairly complete. eiders normally show high site tenacity, usually returning to previously used islands, and sometimes even the same nest cups (reed 1975; parker & mehlum 1991). however, they may move depending on whether the particular nesting island is connected by ice to the mainland early in the season, when the birds select their nest site based on “security concerns” related to access of predators, especially the arctic fox (mehlum 1991a; parker & mehlum 1991). our survey was conducted over two seasons, with no repeated counts in both years at any sites, so it cannot be ruled out that parts of the “regional population” may have been overlooked or double-counted due to this approach. nevertheless, movements from year to year would normally be short (reed 1975; swennen 1990), so since our surveys in 1997 and 1998 covered rather distinct areas, we consider that the possible bias caused by inter-annual movements was minimal. in svalbard, the number of breeding pairs has been shown to be lower in years with late ice break-up (mehlum 1991b). in our survey area, ice break-up was normal in the survey years, so the results should not be significantly affected by unusual ice conditions. the mean clutch size of 3.74 in avanersuaq was higher than values (means between 3.12 and 3.44) found for the same subspecies (s. m. borealis) in areas of baffin and ellesmere islands in eastern canada, and higher than in upernavik, northwest greenland (3.31), and similar to findings of 3.82 from south-west greenland (68° n) in 1997 and 1954 (joensen & preuss 1972; prach et al. 1986; frich et al. 1997; salomonsen, 113christensen & falk 2001: polar research 20(1), 109–114 unpubl. notes). the eider populations of low arctic hudson bay in canada, however, lay large clutches, ranging between 4.0 and 5.6 eggs, possibly because the birds of this subspecies (s. m. sedentaria) are resident so they may have more energy reserves available for egg production (robertson & gilchrist 1998; robertson et al. 2001 [this issue]). since common eiders show a seasonal decline in clutch size (mehlum 1991b; robertson 1995; coulson 1999) our result might partly be biased by the late survey date, when only late, presumably smaller, clutches would be recorded. even so, the clutch size was relatively large, suggesting that conditions for eiders in the area may have been favourable. no data are available from the two known (northern) colonies we could not survey, but archaeologists working in the area in 1996 and 1997 reported active nests (but no numbers) from macgary island (bo bendix, university of copenhagen, pers. comm.). before the late 1980s, local hunters have reported that up to 5000 eggs may have been harvested in some years (dmu-am & oc 1999). although such information is hard to evaluate, egg collection must have been substantial in some years. as the common eiders in the area lay 3 5 eggs, the reported egg collection suggests that more than 1000 nests may have occurred there. hence, combined with our counts of 3800 nests, an educated guess of the total common eider population in avanersuaq would be around 5000 pairs. most of the records in the database on eiders in this area contain secondhand information or very crude estimates rather than actual counts, so we have a weak basis for evaluating population trends. the best available information stems from the group of islands in booth sound, where counts from 1968 indicated a total population of 220 nests, and brief visits in 1987 indicated only about a few hundred nests. comparing these figures to the 866 nests actually counted in 1997 suggests a real increase in this particular sub-area. in general, the results of the 1997-98 survey indicated colonies of similar size, or larger, than previous information suggested—disregarding the dubious cases where “known” colonies could not be confirmed. we therefore consider that the population in avanersuaq may at least have remained stable, and avoided a dramatic decline like that seen in some areas further south in greenland (boertmann et al. 1996; frich et al. 1997). to establish a firm platform for monitoring population trends would require several years of data to account for inter-annual variability— a task hard to accomplish in this large and remote region. but this survey has improved the quantitative information available assessing major population changes in the region. the possibly stable population in north-west greenland raises the question whether the intensive winter hunting in south-west greenland is actually the main reason for the declining populations in both greenland and canada, as is currently assumed. if eiders from different regions mix in mutual staging and wintering grounds with high hunting impact, a widespread—not a localized—population decline would be expected. local declines, however, would be expected if a) eiders from different regions move to separate staging and wintering grounds with different hunting levels, or b) over-harvesting and/or disturbance occur mainly in the breeding areas. to identify migration routes and wintering grounds, satellite telemetry on females from breeding sites in low and high arctic greenland and eastern canada would be desirable, as would be detailed studies on the direct and indirect impact of hunting in the wintering areas. acknowledgements.—we thank kurt thomsen and kristian eipe for safe dinghy navigation throughout the district, and jonas teilmann and erik w. born for assistance in the fieldwork. jan thrysøe and the danish liaison officer at thule air base kindly facilitated our transit stays there. the project was funded through a grant to ornis consult ltd. from the dancea programme of the danish ministry of environment. comments from gregory j. robertson and one anonymous referee helped us improve this paper. references boertmann, d. 1994: an annotated checklist to the birds of greenland. medd. grønl. biosci. 38, 1–63. boertmann, d., mosbech, a., falk, k. & kampp, k. 1996: seabird colonies in western greenland (60°-79°30’ n. lat.). neri technical rep. 170. copenhagen: national environmental research institute. born, e. w. 1987: aspects of present-day maritime subsistence hunting in the thule area, northwest greenland. in l. hacquebord & r. vaughan (eds.): between greenland and america: cross-cultural contacts and the environment in the baffin bay area. pp. 109–132. groningen, the netherlands: university of groningen. caff 1996: international murre conservation strategy and action plan. arctic environmental protection strategy. akureyri, iceland: conservation of arctic flora and fauna international secretariat. caff 1997: circumpolar eider conservation strategy and 114 status of the common eider in avanersuaq, north-west greenland action plan. akureyri, iceland: conservation of arctic flora and fauna international secretariat. cooch, f. g. 1986: the numbers of nesting northern eiders in the west foxe islands, nwt, in 1956 and 1976. in a. reed (ed.): eider ducks in canada. can. wildl. serv. rep. ser. 47, 114–118. ottawa. coulson, j. c. 1999: variation in clutch size of the common eider: a study based on 41 breeding seasons on coquet island, northumberland, england. waterbirds 22, 225–238. cramp, s. (ed.) 1977: handbook of the birds of europe, the middle east and north africa. vol. i. the birds of the western palearctic. oxford: oxford university press. dickson, d. l. (ed.) 1997: king and common eiders of western canada. can. wildl. serv. occas. pap. 94. ottawa: canadian wildlife service, environment canada. dmu-am & oc 1999: database over grønlands havfuglekolonier. (greenland seabird colony database.) copenhagen: national environmental research institute (dept. of arctic environment) and ornis consult ltd. falk, k. & kampp, k. 1997: a manual for monitoring thickbilled murre populations in greenland. tech. rep. 8. nuuk: greenland institute of natural resources. frich, a. s. 1997: ederfuglefangst i grønland 1993. (the bag of common eiders in greenland 1993.) tech. rep. 9. nuuk: greenland institute of natural resources. frich, a. s., christensen, k. d. & falk, k. 1997: ederfugleoptællinger i kangaatsiaq og avanersuaq 1997. (common eider counts in kangaatsiaq and avanersuaq.) tech. rep. 10. nuuk: greenland institute of natural resources. joensen, a. h. & preuss, n. o. 1972: report on the ornithological expedition to northwest greenland 1965. medd. grønl. 191(5), 1–55. kampp, k., nettleship, d. n. & evans, p. g. h. 1994: thickbilled murres of greenland: status and prospects. in d. n. nettleship et al. (eds): seabirds on islands. threats, case studies and action plans. birdlife conserv. ser. 1. pp. 133–154. cambridge: birdlife international. laake, j. l., buckland, s. t., anderson, d. r. & burnham, k. p. 1993: distance user’s guide. ver. 2.0. fort collins, co: colorado cooperative fish & wildlife research unit, colorado state university. mehlum, f. 1991a: egg predation in a breeding colony of the common eider somateria mollissima in kongsfjorden, svalbard. nor. polarinst. skr. 195, 37–45. mehlum, f. 1991b: breeding population size of the common eider somateria mollissima in kongsfjorden, svalbard, 1881-1987. nor. polarinst. skr. 195, 21–29. parker, h. & mehlum, f. 1991: influence of sea-ice on nesting density in the common eider somateria mollissima in svalbard. nor. polarinst. skr. 195, 31–36. prach, r. w., smith, a. r. & dzubin, a. 1986: nesting of the common eider near the hell gate–cardigan strait polynya, 1980-1981. in a. reed (ed.): eider ducks in canada. can. wildl. serv. rep. ser. 47, 127–135. ottawa. reed, a. 1975: migration, homing, and mortality of breeding female eiders somateria mollissima dresseri of the st. lawrence estuary, quebec. ornis scand. 6, 41–47. reed, a. & erskine, a. j. 1986: populations of the common eiders in the eastern north america: their size and status. in a. reed (ed.): eider ducks in canada. can. wildl. serv. rep. ser. 47, 156–162. ottawa. robertson, g. j. 1995: annual variation in common eider egg size: effects of temperature, clutch size, laying date, and laying sequence. can. j. zool. 73, 1579–1587. robertson, g. j. & gilchrist, h. g. 1998: evidence of population declines among common eiders breeding in the belcher islands, northwest territories. arctic 51, 378–385. robertson, g. j., reed, a. & gilchrist, h. g. 2001: clutch, egg and body size variation among common eiders breeding in hudson bay, canada. polar res. 20, 85–94. salomonsen, f. unpubl. notebooks. university of copenhagen. salomonsen, f. 1950: the birds of greenland. copenhagen: munksgaard. salomonsen, f. 1967: fuglene på grønland. (the birds of greenland.) copenhagen: rhodos. swennen, c. 1990: dispersal and migratory movements of eiders somateria mollissima breeding in the netherlands. ornis scand. 21, 17–27. vaughan, r. 1988: birds of the thule district, northwest greenland. arctic 51, 53–58. radiocarbon dated common mussels mytilus edulis from eastern svalbard and the holocene marine climatic optimum christian hjort, jan mangerud. lena adrielsson, stein bondevik, jon y. landvik and otto salvigsen hjort, c., mangerud, j . , adrielsson, l . , bondevik, s . , landvik, j . y . & salvigsen 0. 199.5: radiocarbon dated common mussels mytilus edulis from eastern svalbard and the holocene marine climatic optimum. polar research 14(2), 239-243. the common mussel myrihu edulis is an indicator of milder marine conditions in the arctic. with stronger atlantic water influx. during the holocene and earlier interglacials. twelve holocene radiocarbon dates of myrilus from eastern svalbard fall between ca 8800 and so00 bp and roughly delimit the marine climatic optimum period there. the beginning of this period in the east coincides with the immigration of boreal extralimital molluscs to western svalbard, indicating the culmination of holocene atlantic influence. christian hjort and lena adrielsson, department of quaternary geology, lund uniuersiry. solvegaran 13, s-223 62 lund, sweden; jan mangerud and stein bondeuik, department of geology. sectioii b , unioersiry of bergen, allkgaten 41, n-so14 bergen, norway; jon y . landuik. u n i s , n-9170 longyearbyen. norway; otto saloigsen, norsk polarinsriturt. p. 0. box 5072 majorsma. n-0301 oslo, norway. introduction t h e common mussel mytilus edulis l. is mainly a n intertidal to shallow sub-tidal bivalve, which spreads with pelagic larvae and byssus drifting. i t does not live on svalbard today, but living specimens attached to seaweed, boxes and other items, presumed to have drifted from the south, have been encountered several times during the last hundred years (knipowitsch 1903a; heintz 1926; peacock 1983; mangerud & bolstad unpubl.). however. during the warmer parts of the holo cene, mytilus was common on svalbard, especially on the western coast (summary in sal vigsen et al. 1992: see fig. 1). reports from the colder northern and eastern parts of the archi pelago are fewer. in the east, scattered finds had been made earlier on edgeoya (knipowitsch 1903b) and o n svenskoya in the kong karls land archipelago (nathorst 1901; hagg 1950). nansen (1902) even found it as far east as franz josef land. the ponam expedition during the p o n a m (polar north atlantic margins, late cenozoic evolution. see acknowl edgements) expedition to eastern svalbard in 1991, most major sections in quaternary sedi ments on e d g e ~ y a and barentssya were studied, with extensive work being done also on western k o n g s ~ y a in kong karls land. mytilus was found in raised marine sediments at several localities, but only o n e d g e ~ y a (hjort et al. 1992). where it occurs from ca 45 m a.s.1. to a few metres above the present shore. in some places it was very common, for example at habenichtbukta on southwestern edgeoya, close to krausshavn where it was found during the russian expedition in 1899 (knipowitsch 1903b). t h e dated m-ytilus samples from edgesya and t h e earlier svenskoya find are listed in table i . most of the localities and finds were described by hjort e t al. (1992) and also listed by gulliksen et al. (1992), but four new dated samples, also collected during the p o n a m expedition, have now been added. all known occurrences on edge oya a r e indicated o n fig. 2. radiocarbon dates eleven radiocarbon dates were made on mytilus shells collected o n edgesya during the fonam expedition 1991 (table 1). eight of these were conventional datings made in trondheim and lund and three were ams-datings made in aarhus or uppsala. t h e fragments found on 240 c'. hjort et mi. fig. 1. svalbard. w t h dated myrilus edtrlis finds according to salvigsen et al (1992. open circles) and as added through this study (filled circles, details in fig. 2 ) . tnhlr i radiocarbon dated m\.rllu.r rdrrlis samples from eastern s ~ a l h a r d . except for no. 4 . which is froin kong karls land and wd5 collected in 1898 (nathorst 1901: hagg 1950). all samples are from edgeclya (fig. 2 ) and were collected during the p o n a m expedition in i991 (hjort et al. 1992: gulliksen el al. 1992). the age5 are corrected for a rrservoir effect of -440 years (mangerud 8: gulliksen 1975). h"c is expressed as c r r on the p d b scale. t.ocalit! \mellcdalcn hlafiorddaleii i < d d e d a l c n s\ensho!a scidbreen smelledalen smelledalen smelledalen hnelledalen smelledalen smelledalen f fabenichtbukta .~~~ sample no. m j 5.1 sh-707d r x l i h 86-307 88-739 88-735 86-703a 87-6.53 86-702a hl-655 87-654c 86-701 a 88-71 1 40 39 36 25 i n t i l l 35 37 31 15 28 27 1 age 8 p 8755 2 175 ti510 t 1/11 8210 2 150 7260 i 100 7 ? 0 5 ? 115 7175 * l l t l 7095 -t 5 5 7oy5 2 135 7050 ? 1-11) h88.i z 85 5835 2 125 4960 2 80 ''c lab no t-ygiy t-y9w aar-837 aar-853 t-9922 tua-173 t-i0111 t-992 i t-10145 t-9920 lu-3373 ud-3279 hl 'c collector -0.2 0 1 ( i 3 0.5 1 .o 0.3 0.3 -0.3 0.5 -0.6 j . mangerud & s . bondevik .i. y . landvik 0. stubdrup & s . bondevik g . a n d e r s o n c. hjort .i. mangerud 8: s . bondcvik j . mangerud j . mangerud & s . bondevik j . mangerud j . mangcrud j . mangerud & s . bondevik c. hjort & l. adrielsson radiocarbon dated common mussels mytilus edulis from eastern svalbard 241 78" 1 -77"30' i svenskoya in 1898 were ams-dated in aarhus. all samples have been corrected for a reservoir effect of -440 years, according to mangerud & gulliksen (1975). 125 yrs bp and belong to those collected at the highest alti tudes. the youngest dated shells, from 4960 ? 80 bp at habenichtbukta, were those encountered at the lowest altitude, 4 m a.s.1. our datings thus show that mytilus immigrated to eastern svalbard not later than ca 8800 bp and was still living there around 5000 bp. the oldest shells date from 8755 discussion present distriblction although m y t i l u is not found living on svalbard today, it penetrates far into southeastern barents 212 c hjort et nl. sea (peacock 1989) and u p along the western coast of greenland (funder b weidick 1991). it even maintains populations o n the southeastern coast o f greenland. uithin waters affected by the cold east greenland current (hjort & funder 1974: funder rc weidick 1991). i t also occurs at scattered localities along the eastern coast of baffin island. where arctic water flows south ward in the baffin-labrador current (andrews 1972). mytiliis may thus live under conditions where w m m e r sea-surface temperatures (sst's) approach 0°c. the presence of marginal popu lations which live today in fjord areas inside cold water currents (e.g. in the ammassalik district i n southeastern greenland), indicates an ability to colonise rather local areas with higher than aver age sst's. this m a y occur during years with stronger than average atlantic water penetration (cf. cliccussion in peacock 1989. p. 189). hyp.sitlitwiicil distrihiirioti m y t i l [ i s had a much larger northward distribution during earlier parts of the holocene and has become the classical exponent for warmer-than present conditions in the arctic. svalbard was the area where this first became evident ( e . g . blomhtrand 1861: nathorst 1884; ihiigbom 1913: feylinp-hanssen l y s 5 ) . according to the review by salvigsen et al. (1991). i t immigrated t o the western coast of svalbard before 9500 b p and lived there until around 3500 bp. thereafter it briefly reim migrated during the warm period around 1000 bp. thus it seem\ to have appeared on eactern svalbard some 500--900 vears later than on the western coast. the western and northern coasts are today the a r e a most affected by atlantic water. and that this general pattern prevailed also earlier during the holocene is. for example. indicated by the mid-holocene occurrence only on the central western coast of the boreal molluscs zirpiiea crispata. modiolus tiiodioliis, arcrica islandica and lirtoririn litroren ( feyling-hanssen 1955: salvigsen et al. 1992: mangerud & svendsen 19y2). according to our radiocarbon dates. the immigriition of "llyiihs to eastern svalbard roughl! coincided with the first appearance of boreal molluscs on the west coast. which took place around 8700 b p (salvigsen et al. 1993). thus i t seem3 that it managed to colonise these eastern parts a 5 an effect of a maximum atlantic water influx to the region. but m y t i l i s lived o n along the shores of edgeaya well after the boreal period on the western coast had come t o an e n d , as it did around 7700 bp. nor was our youngest m y i i l u s date. from ca 5000 bp, from a population on the verge of extinction. it then still lived in profusion in a local shallow lagoon environment in hab enichtbukta (adrielsson e t al. 1992). today the waters around edgeaya and kong karls land are dominated by the southwesterly how of arctic water in the east spitsbergen current (e.g. loeng 1991). it seems that a pre condition for the immigration of mytilus into this area. and for its persistence there during ca 4000 years. must have been a weakening of this cold current and a much stronger influx of atlantic water than today. t h e foraminifera1 record in marine sediment cores from western franz josef land, northeast of our study area and much further away from the atlantic source supports this. it indicates that the most favourable marine conditions there. with the strongest atlantic influence, were between 7000-5000 b p (polyak & solheim 1994). how quickly the balance between warmer atlantic and colder arctic waters may indeed shift. over a few decades or less. has recently been documented from the northern coast of svalbard by eggertsson (1994). with the help of driftwood studies. t h e same pattern of early to mid-holocene weakening of cold water outflows from the polar basin. with a markedly stronger atlantic influ ence. has been suggested for both the east green land current and the baffin-labrador current, using myiilus dates (andrews 1972; hjort rc fun der 1974; funder & weidick 1991). a study by koc & jansen (1991), based o n oxygen isotope and diatom stratigraphy in d e e p sea cores from the greenland sea, confirms that this enhanced atlantic influence began to affect the coast of central east greenland ca 8500 b p , which is roughly when m y t h s immigrated (hjort & fun der 1974). t h e atlantic influence diminished from ca 5000 bp. coinciding with the disappearance of myrilus. this further illustrates the close relation ship between oceanographic climatic conditions and the geographic distribution of this pelagically spreading indicator bivalve! a c r ( . t r o ~ ~ l r ~ j ~ e i n r , i t r . p o n a m was a european scicncc foun dation arctic network programme which r a n from 1990 to 1994. t h e norwegian polar inctitutc. thc swcdish polar sccretariai a n d t h e eec (through a grant for helicopter costs t o the euro pean science foundation) supported the expedition i o g i k a l l y a n d the norwegian research council f o r science and tiumani radiocarbon dated common mussels m y t i l u s edulis from eastern svalbard 243 ties and the swedish natural science research council financed the work connected with this study. the natural history museum in stockholm supplied the svenskaya shells for dating. j . d. peacock and k. s . petersen are thanked for constructive reviews. references adrielsson. l.. hjort. c. & johansson, k . 1992: a holocene regression sequence at habenichtbukta, southwestern edgebya. svalbard. i n moller, p., hjort, c. & ingolfsson. 0. (eds.): weichselian and holocene glacial and marine history of east svalhard: preliminary report on the ponam field work in 1991. lundqita rep. 35, 161-170. andrews, j . t. 1972: recent and fossil growth rates of marine bivalves, canadian arctic. and late-quaternary arctic marine environments. paleogeogr., paleoclimatol., paleoe col. 6 6 , 157-176. blomstrand, c. w. 1864: geognostiska iakttagelser under en resa till spetshergen i r 1861, kungl. suenska velenskap sakad. handl. n . f . 4 . eggertsson, 0. 1994: driftwood as an indicator of relative changes in the influx of arctic and atlantic water into the coastal areas of svalbard. polar res. 13, 209-218. feyling-hanssen, r. w. 1955: stratigraphy of the marine late pleistocene of billefjorden, vestspitshergen. norsk polar inst. skr. 107. 186 pp. funder, s . & weidick, a . 1991: holocene boreal molluscs in greenland paleoceanographic implications. paleogeogr. puleoclimatol. paleoecol. 85, 12s135. gulliksen. s . . heinemeier. j . , heier nielsen, s . , nyda. r . , rud. n.. s l o g , g.. skovhus thomsen, m. & landvik, j . y . 1992: "c-dating of samples collected during the 1991 ponam expedition to eastern svalbard. i n moller, p., hjort, c . & lngolfsson, 0. (eds.): weichselian and holocene glacial and marine history of east svalhard: preliminary report on the ponam field work in 1991. lundquu r e p . 35, 191-198. hagg, r. 1950: kvartara marina fossil frin spetsbergen insam lade av svenska expeditioner. geologi.ska foren. stockholm forhandl. 72. 331-347. heintz, a . 1926: blaskjell p i spitsbergen. norsk geogr. tidrskr. 9 , 74-76. hjort, c. & funder. s . 1974: the subfossil occurrence of myrillrs edulis l . in central east greenland. boreas 3,2>33. hjort, c . , adrielsson, l . , bondevik. s . . lnndvik, j. y . . man gerud. j . & salvigsen, 0. 1992: myrilus edulis on eastern svalbard dating the holocene atlantic water influx maxi mum. in moller, p.. hjort, c. & ingolfsson. 0. (eds.): weichselian and holocene glacial and marine history of east svalbard: preliminary report on the ponam field work in 1991. lundqua rep. 35, 171-175. hogbom, b. 1913: om spetsbergens mytilustid. geologisku. foren. stockholm forharidl. 35, 151-156. koc, n . & jansen, e. 1994: response of the high-latitude northern hemisphere to orbital climate forcing: evidence from the nordic seas. geol. 22, 52s526. knipowitsch. n. 1903a: zoologische ergebnisse der russischen expedition nach spitsbergen. mollusca und brachiopoda iv. nachtrag. aiiriiraire de mu.ree zoologique de i'academie imperiale des sciences de sr. petersbourg 8, 133-143. knipowitsch, n. 1903b: zoologische ergebnisse der russischen expedition nach spitsbergen. mollusca und brachiopoda i1 & 111. annuaire du muspe zoologique de l'ilcademic hnper iale des sciences de s1. petersbourg 7. 424-445. locng, h . 1991: features of the physical oceanographic con ditions of the barents sea. polar res. 1 0 , s 1 8 . mangerud, j . & gulliksen, s . 1975: apparent radiocarbon age of recent marine shells from norway. spitsbergen and arctic canada. quat. res. 5 , 263-273. mangerud, j . & svendsen. j . i. 1992: the last interglacial glacial period on spitsbergen, svalbard. qftnr. sci. r e o . 11, 633664. nansen. f . 1902: the oceanography of the north polar basin. the norwegian north polar expedirion 189.7-1896, scient. results 3 . christiania. nathorst. a . g . 1884: redogorelse fbr den tillsammans m d g . de geer i r 1882 foretagna geologiska expeditionen till spetsbergen. biliang krrngl. s o e n s k a verenskapsaknd. handl. 9 , 79 pp. stockholm. nathorst, a . g . 1901: bidrag t i l l kong karls lands geologi. geologiska fziren. stockholm fbrliuiidl. 23, 341-378. peacock, j . d. 1983: two finds of modern shclls of the common mussle ( m y t i l u s edulis) in spitsbergen. porcup. newsl. 2 , 180-181. peacock, j. d. 1989: marine molluscs and late quaternary environmental studies with particular reference to the late glacial period in northwest europe: a review. quri. sci. r e o . 8, 179-192. polyak, l. & solheim, a. 1994: lateand postglacial environ ments in the northern barents sea west of franz josef land. polar res. 13, 197-207 salvigsen, o., forman, s l. 8: miller. g . h. 1992: therm ophilous molluscs on svalbard during the holocenc and their paleoclimatic implications. polar r e f . 11. 1-10, research note an early proterozoic u-pb zircon age from an eskolabreen formation gneiss in southern ny friesland, spitsbergen yu. a. balashov. a. n. larionov. l. f. gannibal. a. n . sirotkin, a. m. tebenkov. g . 1 . ryungenen and y. ohta .. balashov, yu. a . , larionov, a. n.. gannibal. l. f.. sirotkin. a . n., tebenkov, a. m.. ryiingenen, g . i . & ohta. y. 1993: an early proterozoic u-pb zircon age from an eskolabreen formation gneiss in southern n y friesland. spitsbergen. polar research 12(2), 147-152. a preliminary u/pb zircon age determination has been carried out on a grey gneiss of the eskolabreen formation, the lowest observable lithostratigraphic unit of precambrian metamorphic rocks in southern ny friesland. ne spitsbergen. the obtained age, ca. 2,400ma, is considered to be a metamorphic age and suggests an early proterozoic tectonothermal event. yu. a . balashou, a . n . larionov, l . f. cannibal, and c . i . ryungenen. laboratory of isotope geochem istry, geological institute, kola science centre. russian academv of sciences, 14 fersman str., 184200 apatity, russia; a . m . tebenkov and a . n . sirorkin, polar marine geological exploration expedition. 24 pobedu sir., i89510 lomonosou-st. petershurg. russia: y. ohta. norsk polarinstitutt. p. 0. box 5072 majorstua, n-0301 oslo. norway. introduction rcccnt gcochronological works on the pre-caledonian base ment of svalbard have revealed not only a late middle pro terozoic tectonothermal event, the grenvillian (peucat et al. 1989: tebcnkov ct al. 1991: balashov et al. 1992; gee et al. in press), hut also a late early proterozoic event (gee et al. 1992; gavrilenko & kamensky 1992) and some early proterozoic and older u-pb zircon upper interccpt ages (peucat et al. 1989; balashov ct at. 1992) and sm-nd model ages (bernard-griffiths et al. 1993). since the n y friesland area, northeastern spitsbergen. has complex structures (manby 1990: gee et at. 1992) and the largest distribution of the pre-devonian crystalline basement. early proterozoic rocks can naturally be expected. this note reports an early proterozoic u-pb zircon age obtained from a gneiss of the eskolabreen formation, the lowest litho stratigraphic division of the basement rock succession as defined by harland et at. (1966). geological setting n y friesland occupies the middle part of the basement areas of northern svalbard (fig. i ) . the structure in the southern part of ny friesland is dominated by an asymmetric antiform, the atomfjella antiform (harland 1959). the axis plunges gently to the north. the western limb of the antiform is cut by a steep fault zone, dipping 5c-80" to the west, which is a part of the n-s trending billefjorden fault zone (harland et al. 1974), the latter down throws to the west. some carboniferous cover has been preserved on the basement block in the east side of austfjordcn. the castern limb of the antiform is cut by a steep e dipping, partly thrust. fault within the antiform and the finlandvcggcn group is in contact with the harkerbrcen group (table 1 ) by this fault. along the eastern margin of the antiform the harkerbreen group is in contact with the mossel series (krasil'beikov 1973) or the planetfjella group of the upper stubendorffbreen supergroup (harland et at. 1966) by a w dipping thrust fault. the core of the antiform is composed of the smutsbreen and the eskolabreen formations of the finlandveggen group (harland et at. 1966; krasil'sfikov 1973; harland 1985, 1992). the smutsbreen formation consists of grey biotite gneisses with or without garnet and distinctive marble layers. the latter are in both the lower and upper parts, and small amounts of calc silicate-gneisses and amphibolites also present. the esko labreen formation is the lowest observable lithostratigraphic unit and is composed of garnet-hornblende-biotiteand horn blende-biotite gneisses. amphibolites and granitic gneisses. these rocks have upper amphibolite facies mineral assemblages of high temperature scries with andalusite-sillimanite, while the rocks of this formation in the limbs have kyanite-garnet-mica assemblages without sillimanite. indicating a lower temperature condition than in the core and an intermediate temperature pressure series. the flptan granite in the northern part of ny friesland (fig. 1) has a 1,788 + 53/-45 ma u-pb zircon isochron age. it also 148 yu. a. balashou et al. fig. 1. generalized geological map of southern ny friesland. with the sample locality. lnsertcd map: solid square = map area, dashed area = prc-devonian basement, nf = ny friesland, f = flatan granite. legend: cb = carboniferous. pi = planetfjella group or mosscl series. rt = ritlervatnet formation, hk = polhem o r harkerbreen formation. sm = smutsbreen formation. es = eskolabrecn formation, ft = fault and thrust, ant = atomfjella antiform. s with a solid circle = sample locality. yielded zircon single grain ages of ca. 1.70uma (gee ct al. 1992). this granite possibly intruded in the gneisses and amphibolitcs of the polhem formation in the lower part of the harkerbreen group (table 1). thus the protoliths of the gneisses and amphibolites are of early proterozoic. ultramafic rocks separating the polhem formation from the planetfjella group have yielded a ca. 1.8 g a age and a biotite concentrated rock adjacent to them gives an age of 500ma. both by the k-ar method (gavrilenko & kamensky 1992). though the reliability of these k-ar data is a matter of debate. this note presents a preliminary u-pb zircon age obtained from an eskolabreen formation gneiss in southern ny fries land. this age was orally presented by balashov in august 1993 at turku, finland. materials and methods sample description a grey gneiss (ca. 30 kg) from the eskolabreen formation in the middle-southern side of stubendorffbreen has becn used for this isotopic study. the locality is shown in fig. i . the rock is a coarse-grained, feldspar porphyroblastic, garnet-hornblende biotite gneiss with a modal composition of 2.%30% quartz, 2.5 30% plagioclase (an,&, 3 u % k-feldspar, 10% biotite, 1 2% hornblende and i-2% garnet with accessories of apatitc, zircon, monazite and opaques; the secondary minerals are chlor ite, sericite and epidote. this gneiss forms persistent layers, u p to 5 m in each thick a n early proterozoic u p b zircon age from an eskolabreen formation 149 sarrbreen fm vassfaret fm. bangenhuk fm. rittervatnet fm. harkerbreen fm. fig. 2 . morphotypes of the zircon grains. scanning electro-micrographs. upper left, morphotype 1 , x480, upper right, morphotype 1 x ihx; lower left and lower right morphotypc 2, both x 240. d s 3 (d iii 3 v) table 1. lithostratigraphic schemes of middle and early proterozoic successions in ny fricsland, aftcr harland ct a l . (19%) and krasil'sfikov (1y73) smutsbreen fm. eskolabreen fm. harland et al. 1966 planetfjellet group 2 i' i 0, s ~ r b r e e n fm. vassfaret fm. 0 2 bangenhuk fm. i3e rittervatnet fm. 6 s polhem fm. 3 (d krasilscikov 1973 mossel series t ab le 2 . is o to p ic a n al ys es o f u a n d p b fr o m t h e zi rc on f ra ct io ns o f th e m o rp h o ty p e 1 fr o m t h e e sk o la b re en g ne is s '0 7p b / % '0 7p b / % '0 6p b er r 2 3 5 u er r 0 . 1 3 3 4 0. 14 4. 56 7 0. 31 0 . 1 4 8 0 0. 71 6. 88 8 0 . 7 6 0. 14 91 0. 21 7. 47 3 0. 37 0 . 1 4 4 6 0 . 3 5 7. 52 4 0. 45 0. 12 95 0 . 8 2 4 .2 31 0 . 9 6 0 . 1 3 5 0 0. 13 5. 34 0 0. 28 .a b 10 . 1 2 3 4 5 6 20 6p b / % 2 3 a u er r 0 . 2 4 8 3 0. 27 0. 33 76 0 . 2 6 0 . 3 6 3 4 0 . 3 0 0 . 3 7 7 3 0 . 2 6 0 . 2 3 6 9 0. 35 0 . 2 8 6 9 0. 24 s iz e o f fr ac ti o n s b m ) 5 0 7 5 7 5 1 0 0 > l o o > l o o < 5 0 < l o o w ei g h t im g l 0. 8 1. 7 1 0 . 0 8. 6 0. 9 0 . 6 u p b p b p p m ra d io co m m on ge n ic p p m p p ln 3 4 6 9 3 . 9 0 . 6 4 18 9 70 .7 < 0 . 0 0 1 20 3 83 .3 0 . 2 3 15 6 65 .6 0 . 5 2 2 9 4 6 4 . 7 3 0 . 5 0 3 2 7 10 1. 4 1. 02 1 1 3 1 8 3. 8 6 0 6 0 11 .0 4 2 4 5 3. 7 is o t o p ic r a t io s (m ea su re d ) zo g pb / % 'o 'p b er r 7. 38 6 0. 10 6. 69 3 0. 70 6. 66 2 0 . 2 0 6 . 8 2 2 0. 30 4 . 2 1 6 0 . 2 2 7 . 2 5 3 0 . 0 8 2 06 p b / % 20 sp b er r 7. 05 8 0. 14 7. 10 2 0. 50 6. 10 7 0. 30 6 . 4 8 4 0. 15 2. 45 4 0. 44 7 . 6 8 3 0. 31 a g e (m a ) (c al cu la te d ) r h o '0 7p b / '0 7p b/ 20 6p b i 20 6p b 2 3 5 " 2 3 8 u 0. 89 7 2 1 4 3 17 43 1 4 3 0 0. 34 9 2 3 2 3 2 0 9 7 18 75 0. 81 9 2 3 3 6 2 1 7 0 1 9 9 8 0 . 6 2 6 2 2 8 3 2 1 7 6 2 0 6 4 0 . 5 5 6 2 0 9 2 1 6 8 0 1 3 7 0 0. 88 8 2 1 6 4 15 75 16 26 a n early proterozoic u p b zircon age f r o m an eskolabreen formation 151 ness, altcrnating with pink granitic gncisses and thin amphibo lites of hornblende-biotite gncisscs and is located about l00m below thc uppcr boundary of the eskolabreen formation in the core of the atomfjclla antiform. many isoclinal fold hinges occur within layers and the gneissosities arc all of tcctonic metamorphic in origin. zircons two morphotypes of zircon grains arc distinguished in the rock (fig. 2): ( i ) grains with facets of ( 1 1 1 ) . (311). (110). (100) and wide bulging margins between them. having apparent oval or roundcd outlines with the width/lcngth ratios 1.5-2.5. they have smooth surfaces and arc commonly transparent. yellow to brownish in colour. some grains have thin overgrowths at thc pinacles. (2) prismatic grains with ( 1 1 i ) and (100) facets. these have relativcly rough surfaces and the width/length ratios are 2-3.5. the colours are similar to morphotypc i . but darker and not as clear duc to thc rougher surfaccs. zircons of both morphotypcs have some inclusions of brown nccdlcs. probably thorite. and glass-liquid bubbles. the surfaces of grains do not show any abrasion pattern as usually seen on the surfaces of detrital grains. thermal-ion mass-spectrometry studies on both types of zircon grains show a large difference in 2"7pb/zhpb age (ca. 2.36 and 1.87 ga), indicating at least two generations of the grains. the zircons of morphotype 2 have not been analysed in this preliminary study because they are considered to have a complex history of crystallization and would therefore give results difficult to interpretate. six size fractions of morphotypc 1 zircon grains have been chosen for the prcsent u/pb analyscs. only transparent grains without ovcrgrowth at the pinacles have bccn selected. fraction 4 was air-abraded to remove the inner part and fraction 6 was additionally milled. isotope anulyses and results extraction of u and pb was performed by krogh's (1973) method. aftcr being washed with diluted nitric acid, the zircon grains were dissolved in 2 ml h f in teflon capsules and heated in aluminium bombs in an oven at 185°c for some days. aftcr dissolution and aliquotation. thc id part was spiked with a mixed 235u-208pb tracer. u and pb wcrc separated by ion exchange using 6.2 m hci and water. total blank during the experiments were 0.05 ng for u and 0.1-0.5 ng for pb. thc sample was loaded with nitric acid on a double re filament for u and with silica gel and phosphoric acid on a single re filament for pb. both wcrc analyscd with a mi 1201-t single collector mass spectrometer. the results of the measurements were corrcctcd for blanks of 0.5 ng for pb and 0.05 ng of u . and common lead using stacey & kramer's model (1975) for an age of 2.450 ma. the results of u and p b isotope analyses are given in table 2 and the obtained isochron is illustrated in fig. 3. the four fractions define a discordia with an upper intercept of 2.415 + -34 ma and a lower intercept of 624 + -68 ma, with mswd = 6.9. two fractions, 4 and 6, are off from the discordia, probably duc to later thermal effects and/or contamination during the air-abrasion for fraction 4. e'a#] 0.44 fig. 3 . u-pb concordia diagram. number of sample refers to table 2. discussion close structural observations of the stubendorffbreen supergroup in this area show that all layered and banded structures in the rocks are of tectonic origin: no stratigraphic (scnsu stricto) definition is therefore possible and the suc cessions must be defined as lithostratigraphic of tectono stratigraphic units (manby 1990; gee et al. in press). the protoliths of the rocks of the harkcrbrcen and fin landveggcn groups have been considered to be areno-argil laceous and arkosic sediments and hi-modal igneous rocks of mostly eruptive origin. the volcanigenic origin of somc of these rocks has also been discussed by manhy (iwo) and sirotkin (unpubl. report). the latter author suggested a difference in a sedimentary environment for these groups, an extensional deep sea basin for the finlandveggen group and a transgressional shallow sea subaerial basin for thc harkerbrcen group. all previous authors agreed that these two groups bclong to a large volcani-sedimentary succcssion without any orogenic break within it. though all observed contacts bctwccn thc two groups are cut by thrust o r steep fault in southern ny friesland. the obtained u-pb upper interccpt age can be considered as a metamorphic zircon age, judging from the transparent colour. smooth surfaces lacking any trace of abrasion and the absence of any clearly zoned structure. this age is applicable to both the eskolabreen and the smutsbreen formations. since these are conformable both in structure and metamorphism. but this age is not applicable to the harkerbreen group since this group is separated by faults from the smutsbreen formation in this area. this u-pb upper intercept age suggests an older tec tonothermal event than the emplacement of the flitan granite at ca. 1.7 g a (gee et al. 1992) in ny friesland. similar ages of ca. 2.4-2sga have also been obtained recently from u-pb upper intercepts of zircon from a quartz porphyryrhyolite clasts in a conglomerate-pyroclastic unit of the northwestern hornsund (balashov et al. 1992). 152 yu. a. balashou et al. thc caledonian and precambrian rocks of ny fricsland have becn compared with those of east greenland (harland 1985; gee et al. 1992). there the 4 1 0 k m thick krummcdal sup racrustal sequence (higgins 1988) has been metamorphosed during the grenvillian period (e.g, peucat et al. 1985), while much older u-pb zircon uppcr intcrccpt agcs. ca. 1.9-3.oga (hanscn & friderichsen 1987; hansen el al. 1987) and ca. 2.5 ma (peucat et al. 1985) have also bccn rcportcd. howevcr. thcsc rocks are involved in complex gneiss-migmatite structures and the discrimination between middle and early proterozoic rocks has not yet been completed. thc palinspastic position of svalbard before cenozoic ocean spreading is not too far from northern ellcsmcrc island. and a structural unit of calcdonian affinity, pcarya, has bccn rccog nizcd in that area (trettin 1987). recent u-pb zircon studies on the caledonian and older rocks in pcarya yielded older agcs than thc grcnvillian, ca. 2.1 and ca. 2.2ga (trettin et al. 1992). both are considered to be from inherited zircons, but no geological constraints arc known yct. no correlative geological event has cvcr bccn observed in the present area which corresponds with thc lower intercept age, ca. 625 ma. but a fcw similar rb-sr and k-ar ages arc known in the northern parts of nordaustlandct (hamilton & sandford 1964; ohta 1992). a similar agc for cclogitic meta gabbroic rock has been obtained from biskayerhalveya (peucat ct al. 1989). this period corresponds to the time of the baikalian event in the southeastern barcnts sea rcgion: however, all these agcs in svalbard are from igneous rocks and no distinguishing structural event of this period has yet hccn rccognizcd. acknowledgements. t h e authors arc gratcful for critical com ments to the manuscript given by d. g. gee, university of lund. sweden, and a. johansson. swedish museum of natural history, stockholm. wc would also likc to thank a . a. krasil'seikov, polar marine geological expedition. lomono sov. russia, for organizing of the projcct. references balashov, yu. a , , fedotov, j . a., skufjin, p. k., sharkov. i. v . . kravchcnko. m. p., shcrstobitova. g . m. & uliancnko, n. a. 1992: evoljucia vulcanizma v pcchengskoy osadochno vulkanogennoy tolsche po rb-sr izotoponym dannym. tezisy xi11 simpvsiuma geochimii isotopov. moskwa, geochi, rossijskaja academija nauk. pp. 1 6 1 7 (in russian). bernard-griffiths, j . , pcucat. j. j . & ohta. y. 1993: age and nature of protoliths in a caledonian blueschist-eclogite complex of western spitsbergen: a combined approach of u pb, sm-nd and ree wholc rock systcms. lithos 30. 81-90, bojanova, t . b. & jacovenchuk, v. n. 1992: u-pb datirovanie baddeleita i zirkona granofirovyh porod imandra-varzugskoy struktury. doklady rossijskoj academi i nauk 322, 136141 (in russian). gavrilenko, b. v. & kamensky, 1. l., 1992: k-ar isochronnyi vozrast i isotopy kalija v hyperbasitovoj dake na poluostrove mosscl, ny fricsland, spitsbergen. geochimija 2, 1 2 6 1 2 9 (in russian). gee, d. g., bjorklund, l. & stolen, l-k. (in press): early proterozoic basement in ny friedand.-implications for the caledonian tectonics of svalbard. tectonophysics. gcc. d. g . , schouenborg. b.. peucat, j . j . , abakumov, s . a., krasil'sfikov, a. a . & tebenkov, a . m. 1992: new evidence of basement in the svalbard caledonidcs: early proterozoic zircon agcs from ny friedand granites. norsk geol. tirlsskr. 7 2 , 181-190. hamilton, e. 1. & sandford, k. s. 1964: rubidium-strontium agcs from north-east land (spitsbergcn). nature 201, 1 2 0 6 1209. hansen, b. t . & friedcrichsen. j. d. 1987: lsotopic age dating in livcrpool land. east greenland. gr0n. geol. under s0gelse rapp. 134. 25-37. hansen, b. t . , steiger. r. h., hcnrikscn. n. & borchardt. b. 1987: u-pb and rb-sr agc determinations on caledonian plutonic rocks in the ccntral part of the scorcshy sund rcgion. east greenland. gron. geol. unders0gelse rapp. 134. 5-24. harland, w. b. 1959: the caledonian sequence in ny fricsland. spitsbergcn. q. j . geol. s o c . london 114. 307-342. harland, w. b. 1985: calcdonidc svalvard. pp. 999-1001l in gee, d. g. & sturl, b. (eds.): the caledinide orvgrny scandinavia and related areas, part 2 . john wilcy & sons. chichester. harland. w. b. 1992: the ny fricsland orogcn. spitsbcrgcn. geol. mag. 129. 67y-708. harland, w. b.. wallis, r. h . &gayer. r. a . 1966: a rcvision of the lower hecla hoek succession in ccntral north spits bergen and correlation clsewherc. geol. mag. 103, 70!-97. harland. w. b . , cutbill, j . l., friend. p. f., cobbctt. d. j.. holiday, d. w.. maton. p. i . . parkcr. j . r. & wallis, r. h. 1974: the billdfjorden fault zone, spitsbcrgcn. norsk polarinrt. skr. 161. 72 pp. higgins, a . k. 1988: the krummcdal supracrustal scqucncc in east grecnland. pp. &96 in winchcstcr, j . a . (ed.): l u f f proterozoic stratigraphy of the northern atlantic region. blackie. glasgow. krasil'sfikov, a . a. 1973: strstigrafija i palcotcctonica docam brijuranncgo palcozoya spitsbergen. trudy lnstituta geologii arktiki 172, 1-119 (in russian). krogh, t. e . 1973: a low-contamination method for hydro thermal dissolution of zircons and extraction of u and pb for isotopic age determinations. gevrhemica et cosmochemica acta 37,485-494. manby, g . m. 1990: the petrology of the harkcrbrccn group. ny friedand, svalbard: protoliths and tectonic significance. geol. mag. 127. 129-146. ohta, y . 1992: recent understanding of the svalbard basement in the light of new radiometric age determinations, norsk geologisk tidskrift 72, 1-6. peucat, j. j.. tisserant, d., caby. r. & claucr, n. 1985: resistance of zircons to resetting in a prograde metamorphic sequence of caledonian age, east greenland. can. j . earth sci. 22, 330-338. peucat, j . j . . ohta. y. & gee, d. g. and bernard-griffiths, j. 1989: u-pb, sr and nd evidence for grcnvillian and latest proterozoic tectonothcrmal activity in the spitsbcrgcn calc donidcs. arctic ocean. lithos 22, 275-285. staccy. j. s. & kramer, j. d. 1y75: approximationofterrestrial lead isotope evolution by a two-stage model. earth planet. sci. lett. 26, 207-221, tebenkov. a . m. balashov. yu. a. & krasil'sfikov, a. a . 1991; trace of pre-paleozoic events in svalbard caledonides. terra abstract supplement 4 to teru nova 3 . p. 32. trettin, h. p. 1987: pearya: a composit tcrrane with caledonian affinities in northern ellesmere island. can. j . earth sci. 2 4 , 224245. trettin, h. p., parrish, r. r. & ruddick, j . c. 1w2: ncw u pb and 40ar-39ar age determinations from northcrn ellcs mere and axel heibergh islands. northwcst territories and their tectonic significance. radiogenic age and isotopic studies: report 6 , geol. survey of canada. paper 92-2. s 3 0 . no job name arctic cephalopod distributions and their associated predatorspor_146 209..227 kathleen gardiner & terry a. dick biological sciences, university of manitoba, winnipeg, manitoba r3t 2n2, canada abstract cephalopods are key species of the eastern arctic marine food web, both as prey and predator. their presence in the diets of arctic fish, birds and mammals illustrates their trophic importance. there has been considerable research on cephalopods (primarily gonatus fabricii) from the north atlantic and the west side of greenland, where they are considered a potential fishery and are taken as a by-catch. by contrast, data on the biogeography of arctic cephalopods are still incomplete. this study integrates most known locations of arctic cephalopods in an attempt to locate potential areas of interest for cephalopods, and the predators that feed on them. international and national databases, museum collections, government reports, published articles and personal communications were used to develop distribution maps. species common to the canadian arctic include: g. fabricii, rossia moelleri, r. palpebrosa and bathypolypus arcticus. cirroteuthis muelleri is abundant in the waters off alaska, davis strait and baffin bay. although distribution data are still incomplete, groupings of cephalopods were found in some areas that may be correlated with oceanographic variables. understanding species distributions and their interactions within the ecosystem is important to the study of a warming arctic ocean and the selection of marine protected areas. keywords arctic ocean; canada; cephalopods; distributions; oceanography; predators. correspondence terry a. dick, biological sciences, university of manitoba, winnipeg, manitoba r3t 2n2, canada. e-mail: tadick@cc.umanitoba.ca doi:10.1111/j.1751-8369.2010.00146.x cephalopods are found in all marine habitats of the world, and are prey for a variety of commercial and culturally significant species. cephalopod distributions are correlated (hjort & ruud 1929; bjørke 2001) with predators such as narwhals (monodon monoceros l.) (e.g., finley & gibb 1982; bjørke 2001) and greenland halibut (reinhardtius hippoglossoides walbaum) (e.g., orr & bowering 1997; dawe et al. 1998; bjørke 2001). a species of interest is the squid gonatus fabricii lichtenstein, which is considered a keystone species in several arctic food webs (chambers & dick 2007). gonatus fabricii are high in lipids and an excellent source of energy (hooker et al. 2001; frandsen & wieland 2004). these squid are also predatory on a variety of fish and other marine invertebrates (e.g., nesis 1965), enabling a transfer of energy from the productive epipelagic zone to benthic waters through ontogenetic migrations (sennikov et al. 1989). a significant body of research has been conducted on cephalopods around greenland (e.g., collins 2002; zumholz & frandsen 2006), norwegian (kristensen 1977; wiborg et al. 1982) and russian waters (e.g., nesis 1965, 2001). however, cephalopods of the canadian arctic (above 60°n) are not well known. most reports (e.g., clarke 1966; kristensen 1983; o’dor & macalaster 1983; nesis 2001) have focused on potential commercial species (e.g., g. fabricii) and their presence or absence in an area, whereas others have been general surveys. the objectives of this work are to: (1) consolidate all distributional data to a single source; (2) present maps to identify areas of biodiversity interest and potential feeding areas (i.e., predator–prey interactions); and (3) establish a baseline for future comparisons, including climate change effects in the arctic. materials and methods initial queries into arctic cephalopods were conducted using the global biodiversity information facility website (http://www.gbif.org/). all cephalopod records for areas north of 60°n were acquired, and five taxa were determined to be the most abundant. of those taxa, records were obtained through contacts with museums (the canadian museum of nature [cmnml] in ottawa, ontario, and the atlantic reference centre [arc] in st. andrew’s, new brunswick), organizations such as arctic ocean diversity (arcod, at the university of alaska polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 209 mailto:tadick@cc.umanitoba.ca http://www.gbif.org fairbanks) and the us national oceanic and atmospheric administration (noaa) ocean explorer project, and unpublished data of one of the authors (tad) as well as unpublished data provided in 2007 by l. harwood, b. bluhm and d. hardie. data and locations were also obtained from published literature (e.g., wiborg et al. 1982; nesis 2001; muus 2002; raskoff et al. in press). the geonames website was used to determine the most likely latitude and longitude in lieu of the given place name. all samples listed from arctic communities were assumed to be caught at the nearest marine location. additional locations were identified from published, geo-referenced maps (nesis 1965; kristensen 1977, 1982; wiborg et al. 1982; sennikov et al. 1989). if the identification from a location was questionable (e.g., fishery survey) the specimens were listed as unidentified. if a specimen was described from a broad region (e.g., bay, sea, ocean), it was not mapped but was listed in table 1. specific sites were averaged from start and end trawl locations. sample numbers were denoted with incrementally larger markers. all specimens from the northwest atlantic fisheries organization (nafo) fishery survey of 2007 (m. treble, pers. comm.) were identified by one of the authors (kg). specimens from the cmnml collection from frobisher bay (cmnml 35058) and cape parry (cmnml 37887, 37897, 37891) were examined to verify the original identification, and were found to be correct. the identification of arc specimens, primarily from the mercer collection, table 1 additional reported cephalopod species from the circumpolar arctic. species locations architeuthis sp.a,b,c iceland, norwegian coast, south-west greenland bathypolypus sp.d,e,f baffin bay, hudson strait, south-west greenland bathypolypus bairdiid,e,g,h baffin bay, davis strait, denmark strait, east greenland, south-west greenland, iceland, norwegian coast, south of svalbard bathypolypus pugniger sp.e,h baffin bay, denmark strait, faroe islands, iceland, south-west greenland benthoctopus sp.b,i,j,k faroe–shetland strait, kara sea, norwegian coast, resolute bay (nunavut), east svalbard benthoctopus hokkaidensisl point barrow, alaska benthoctopus profundoruml point barrow, alaska benthoctopus sibericusb,j east siberian and laptev seas brachioteuthis riiseib faroe islands, norwegian coast, norwegian sea, south iceland eledone cirrhosab,m iceland, norwegian coast, norwegian sea, svalbard gonatus sp.d,e,f,i,n,o baffin bay, east baffin island, cumberland strait (mouth), foxe basin, southern tip of greenland, south-west greenland, hudson strait, point barrow (alaska) graneledone verrucosab south of iceland grimpoteuthis sp.i,p denmark strait illex illecebrosusa,b south greenland (frederikshaab), iceland loligo forbesiiq,r north sea, norwegian coast, norwegian sea moroteuthis robustas gulf of alaska ommastrephes bartramib north-east greenland, norwegian sea onychoteuthis banskib south of iceland, north coast of norway opisthoteuthis sp.t,u davis strait, gulf of alaska, south iceland opisthoteuthis borealisv south-west greenland, south iceland rossia sp.e,f,w baffin bay, denmark strait, hudson strait, north somerset island (nunavut) rossia glaucopisb,g,m,n,q,r,x barents sea, around the faroe islands, east greenland, kara sea, iceland, north sea, svalbard rossia macrosomab faroe islands, norwegian coast rossia megapteraa,y davis strait semirossia tenerab laptev sea, norwegian coast sepiola atlanticab,m south of iceland, iceland sepiola rondelettiy ellesmere island, jones sound stauroteuthis syrtensist davis strait, denmark strait teuthowenia megalopsb,g,i,z denmark strait, south-west greenland, south iceland todarodes sagittatusb,m faroe islands, iceland, north coast of norway todaropsis elbanaeaa north sea, norway a berry 1925; b grimpe 1933; c nesis et al. 2003 (1985); d northwest atlantic fisheries organization (nafo) fishery survey of 2004 (m. treble, pers. comm.); e treble 2007; f nafo survey of 2007 (m. treble, pers. comm.); g muus 1962; h muus 2002; i smithsonian national museum of natural history invertebrate zoology collections; j nesis 2001; k muus (2002) reported that the benthoctopus type specimen is actually a bathypolypus spp. therefore any mention of benthoctopus piscatorum has been listed as benthoctopus sp.; l mercer 1968; m taxonomic information system for the belgian coastal area database; n atlantic reference centre database; o piatkowski & wieland 1993; p referred to in this article as opisthoteuthis megaptera, an invalid species name according to the integrated taxonomic information system (2008); q historical benthic dredge samples from the southern baltic and the north sea database; r kondakov 1937; s north pacific groundfish observer database; t collins 2002; u nesis 2003 (1989); v collins 2005; w d. hardie (pers. comm. 2007); x atlantic reference centre; y academy of natural sciences malacology database; z nesis 1965; aa swedish museum of natural history: invertebrates database. arctic ocean cephalopod distribution and predators k. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd210 was previously verified by the senior author. although location data were only used from reputable sources, there is the chance of mis-identifications, especially with bathypolypus arcticus prosch. holdings of this particular species should be re-examined to verify its speciation. the names of all species were validated, and those considered invalid were listed as their synonym in accordance with the integrated taxonomic information system. beaks and specimens from stomach content analyses were recorded as such in the data set. locations were obtained from published literature, government documents, surveys, arctic expeditions (e.g., wacasey et al. 1979; nesis 2001; cephbase) and unpublished data (t.a. dick; l. harwood, pers. comm. 2007) (tables 1–4). each predator species was identified with a unique symbol that differed from specimens recovered from trawls. again, if a location was described from a broad region, it was not mapped. predators and capture locations are listed in tables 2–4. all locations were mapped using arcmap 9 (esri gis mapping software). results specimens described in this paper were collected between 1856 and 2007. the five most prominent species from the table 2 percentages of cephalopod prey items reported from the stomachs of arctic predators. location predators cephalopod prey % of diet (weight) bering sea baird’s beaked whale (berardius bairdii)a cephalopods 90% bearded seals (erignathus barbatus)a octopods <1% beluga whale (delphinapterus leucas)a cephalopods 2% bering sea beaked whale (mesoplodon stejnegeri)a cephalopods 90% dall’s porpoise (phocoenoides dalli)a squid 50% fin whale (balaenoptera physalus)a cephalopods 2% harbour porpoise (phocoena phocoena)a squid 1% harbour seal (phoca vitulina)a squid 4% humpback whale (megaptera novaeangliae)a cephalopods 1% killer whale (orcinus orca)a cephalopods 20% minke whale (balaenoptera acutorostrata)a cephalopods 1% northern fur seal (callorhinus ursinus)a squid 33% northern sea lion (eumetopias jubatus)a squid 3% pacific walrus (odobenus rosmarus)a octopods 1% ribbon seal (histriophoca fasciata)a squid 1% sperm whale (physeter macrocephalus)a cephalopods 82% spotted seal (phoca largha)a squid <1% bjørnøya and bleiksøy islands thick-billed murre (uria lomvia)b squid 30% common murre (uria aalge)b gonatus fabricii 40% clyde bearded seal (erignathus barbatus)c,d bathypolypus arcticus <1% gonatus sp. <1% grise fjord bearded seal (erignathus barbatus)c,e bathypolypus arcticus <1% gonatus sp. <1% iceland hooded seal (cystophora cristata)f gonatus sp. 79% norwegian waters sperm whale (physeter macrocephalus)g gonatus sp. 96% haliphron 1.60% histioteuthis 1.20% teuthowenia 0.34% todarodes 0.43% eastern norwegian waters sperm whale (physeter macrocephalus)f cranchiidae 25% gonatus sp. 9% histioteuthis 38% pond inlet bearded seal (erignathus barbatus)c,h bathypolypus arcticus <1% gonatus sp. <1% narwhal (monodon monoceros)i,j,k squid <5% a perez 1990; b barrett et al. 1997; c finley & evans 1983; d finley & evans (1983) reported that bearded seals from the clyde had a 57% occurrence of b. arcticus and gonatus sp. in their stomachs. e finley & evans (1983) also reported bearded seals from grise fjord, nu, had a 67% occurrence of b. arcticus and a 71% occurrence of gonatus sp. in their stomachs. f bjørke 2001; g santos et al. 2001; h finley & evans (1983) described an occurrence of 85% b. arcticus and 77% gonatus sp. in the stomachs of bearded seals caught off pond inlet, nu. i finley & gibb 1982; j estimates from pond inlet in 1978 described a 92% occurrence of g. fabricii and a 16% occurrence of b. arcticus in the stomachs of narwhals caught. in 1979, 79% of narwhals had g. fabricii and 17% had b. arcticus remains in their stomachs (finley & gibb 1982). k finley & gibb (1982) reported that narwhals in pond inlet were feeding on cephalopods, in particular, g. fabricii. arctic ocean cephalopod distribution and predatorsk. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 211 canadian arctic are g. fabricii, rossia moelleri steenstrup, r. palpebrosa owen, b. arcticus and cirroteuthis muelleri eschricht. gonatus fabricii distribution gonatus fabricii has a circumpolar distribution, extending from alaska north to the high arctic (fig. 1). the canadian range extends from the dolphin and union strait, northwest territories (nwt), north to cape vera, nunavut (nu), and pond inlet, nu, and south through the hudson strait (fig. 1). g. fabricii also extends along the coasts of greenland, through the denmark strait, norwegian sea, off the norwegian shore, around the faroe islands and svalbard, and into the barents sea (figs. 1, 2). because of the number of groundfish and shrimp surveys in the norwegian sea and west coast of greenland, there are numerous records of g. fabricii (nesis 1965; kristensen 1977; wiborg et al. 1982; sennikov et al. 1989). other areas of interest include cape vera (190 specimens) and pond inlet (46 specimens) (figs. 1, 2). wiborg et al. (1982) also identified potential spawning sites in the norwegian sea (fig. 2). distributions around greenland and hudson strait are based on samples collected in trawls, whereas those from cape vera and pond inlet are from stomach contents of northern fulmars (fulmarus glacialis l.) and narwhals, respectively (fig. 3). several hudson strait locations are from the stomachs of thick-billed murres (uria lomvia l.), whereas most of the locations in the eastern arctic are based on stomach contents from commercially fished haddock (melanogrammus aeglefinus l.), greenland halibut and cod (gadus sp. l.) (fig. 3). rossia moelleri distribution rossia moelleri has a circumpolar distribution, with a range extending from cape parry, nwt, through the dolphin and union strait, nwt, to foxe basin, frobisher bay and north to slidre fjord, ellesmere island (fig. 4). it was also recorded from western greenland and denmark strait (fig. 4). there are records from the norwegian sea north to svalbard, with one specimen reported from the laptev sea (fig. 4). cape parry (12 records) and slidre fjord (nine records) have the greatest number of recorded specimens (fig. 4). most records are from trawls. one beak was collected from a walrus (odobenus rosmarus l.) off the north-west tip of greenland (fig. 5). records from the norwegian sea and denmark strait are primarily from the stomachs of cod. one was from the stomach of a haddock (fig. 5). rossia palpebrosa distribution most records of r. palpebrosa are reported from the junction of the east siberian and laptev seas and the laptev sea proper (fig. 6). individuals were recorded from svalbard, the kara and barents seas, as well as from the northern tip of greenland to disko bay, across davis to the hudson strait (fig. 6). individuals were also collected from slidre fjord, ellesmere island, frobisher bay and the east coast of somerset island (fig. 6). there are no records of predators for this species. bathypolypus arcticus distribution the arctic range of b. arcticus extends from frobisher bay north through davis strait to pond inlet, devon island table 3 percentage occurrences of cephalopod prey items from the stomachs of arctic predators (percentages of predators sampled with cephalopods in their stomachs). location predators cephalopod prey % occurrence in stomachs andenes sperm whale (physeter macrocephalus)a squid 83.3 baffin bay, greenland narwhal (monodon monoceros)b gonatus fabricii 35 barrow (alaska) bearded seal (erignathus barbatus)c octopus spp. 69.4 barrow (alaska), holman (canada) ringed seal (pusa hispida)c cephalopods 2.6 davis strait greenland halibut (reinhardtius hippoglossoides)d,e cephalopods 2 greenland sea pack ice harp seal (phoca groenlandica)f gonatus sp. 40 hooded seal (cystophora cristata)f gonatus sp. 82 hendrickson island beluga whale (delphinapterus leucas)g cephalopods 3 jan mayen northern bottlenose whale (hyperoodon ampullatus)a cephalopods 75 kendall island bird sanctuary beluga whale (delphinapterus leucas)g cephalopods 3 little diomede island (alaska) spotted seal (phoca largha)c squid 2.6 north-east iceland northern bottlenose whale (hyperoodon ampullatus)a gonatus sp. 100 a bjørke 2001; b laidre et al. 2004; c dehn et al. 2007; d orr & bowering, 1997; e orr & bowering (1997) also commented that greenland halibut preyed on gonatus sp. in the davis strait; f haug et al. 2004; g l. harwood (pers. comm. 2007). arctic ocean cephalopod distribution and predators k. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd212 table 4 anecdotal accounts of cephalopods as prey species from the arctic. location predators cephalopod prey admiralty inlet narwhal (monodon monoceros)a squid akpatok island thick-billed murre chicks (uria lomvia)b gonatus fabricii arctic/sub-arctic waters of north america and eurasia beluga whale (delphinapterus leucas)c cephalopods atlantic side of arctic narwhal (monodon monoceros)d squid barents sea harp seal (phoca groenlandica)c squid hooded seal (cystophora cristata)c gonatus sp. barrow (alaska) bearded seals (erignathus barbatus)e octopus sp. barrow (alaska), holman (canada) ribbon seal pups (histriophoca fasciata)e cephalopods spotted seals (phoca largha)e cephalopods walrus (odobenus rosmarus)e octopus sp. barrow strait narwhal (monodon monoceros)a squid canadian arctic bearded seals (erignathus barbatus)e octopus sp. coats island thick-billed murre chicks (uria lomvia)b gonatus fabricii digges island thick-billed murre chicks (uria lomvia)b gonatus fabricii east coast of greenland, denmark strait harp seal (phoca groenlandica)f gonatus fabricii hooded seal (cystophora cristata)f gonatus fabricii eastern bering sea beluga whale (delphinapterus leucas)d cephalopods greenland halibut (reinhardtius hippoglossoides)d squid harp seal (phoca groenlandica)d squid hooded seal (cystophora cristata)d squid sperm whale (physeter macrocephalus)d squid eclipse sound narwhal (monodon monoceros)a squid greenland beluga whale (delphinapterus leucas)g cephalopods hantzsch island thick-billed murre chicks (uria lomvia)b gonatus fabricii high arctic northern bottlenose whale (hyperoodon ampullatus)h gonatus sp. long-finned pilot whale (globicephala melas)i gonatus sp. sperm whale (physeter macrocephalus)i gonatus sp. iceland–faroe ridge cod (gadus sp.)h gonatus sp. ommastrephidae halibut sp.h gonatus sp. ommastrephidae irminger sea, south iceland northern bottlenose whale (hyperoodon ampullatus)j gonatus sp. lancaster sound narwhal (monodon monoceros)a squid navy board inlet narwhal (monodon monoceros)a squid northern bering and chukchi seas beluga whale (delphinapterus leucas)g gonatus sp. octopus sp. norwegian sea beluga whale (delphinapterus leucas)j gonatus sp. blue ling (molva dypterygia)j gonatus sp. cod (gadus sp.)j gonatus sp. greenland halibut (reinhardtius hippoglossoides)j gonatus sp. greenland shark (somniosus microcephalus)j gonatus sp. grenadier fish sp.j gonatus sp. harp seal (phoca groenlandica)j,k gonatus sp. squid hooded seal (cystophora cristata)j,k gonatus sp. gonatus sp. narwhal (monodon monoceros)j gonatus sp. northern bottlenose whale (hyperoodon ampullatus)j gonatus sp. long-finned pilot whale (globicephala melas)j gonatus sp. saithe (pollachius virens)j gonatus sp. sea perch sp.j gonatus sp. seabirdsj gonatus sp. sowerby’s beaked whale (mesoplodon bidens)j gonatus sp. sperm whale (physeter macrocephalus)j gonatus sp. peel sound narwhal (monodon monoceros)a squid pond inlet, eclipse sound, admiralty inlet narwhal (monodon monoceros)l squid prince regent inlet narwhal (monodon monoceros)a squid arctic ocean cephalopod distribution and predatorsk. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 213 and lady ann strait, and along the west coast of greenland (fig. 7). records exist from the middle of the east coast of greenland through denmark strait to iceland, and down to the faroe islands (fig. 7). bathypolypus arcticus is also found offshore of norway and in the norwegian sea to svalbard (fig. 7). there are also reports from the kara and laptev seas (fig. 7). the most western distribution is from the canada basin, north of alaska (fig. 7). areas of interest are kap powlett, greenland and the laptev sea (fig. 7). specimens are typically recovered from trawls. one was found in the stomach of a narwhal caught at pond inlet (fig. 8). the specimen from lichtenaufjord, greenland, was from the stomach contents of a greenland halibut (fig. 8). cirroteuthis muelleri distribution the majority of c. muelleri specimens are from baffin bay, and the norwegian and greenland seas, with a few records from the laptev sea (fig. 9). c. muelleri is also reported from the deep water of the canada basin (raskoff et al. in press; b. bluhm, pers. comm. 2007), and from davis strait and baffin bay (fig. 9). unidentified cephalopods although not much cephalopod research has been conducted in the canadian arctic, there are records of unidentified cephalopods (typically from fishery or bird surveys) from areas such as pond inlet, arctic bay, cape vera, somerset island and peel sound, nu, with other records from liverpool bay, southern banks and victoria islands, nwt (fig. 10). rare species of the canadian arctic ocean and adjacent areas deep-sea squid like the giant squid (architeuthis sp. steenstrup) and temperate species such as illex illecebrosus lesueur and sepiola atlantica d’orbigny have been reported from greenland (e.g., berry 1925; grimpe 1933; nesis 1987; table 1). architeuthis sp. have also been reported from iceland and the norwegian coastline, wheras loligo forbesi steenstrup has been reported from the norwegian sea (table 1). rossia glaucopis loven is reported along the eastern shore of greenland, and its presence was noted in svalbard, the faroe islands, and the barents and kara seas (table 1). bathypolypus bairdii verrill and muus’s (2002) proposed species bathypolypus pugniger were found through the denmark strait and around greenland, with b. bairdii extending west into the davis strait (table 1). both were reported (treble 2007) from baffin bay in the 2006 nafo fishery survey (table 1). numerous gonatus sp., bathypolypus sp. and rossia sp. were also collected throughout the hudson strait (table 1). cephalopod–predator interactions the percentage of diets comprising cephalopods of various arctic species is listed in table 2. cephalopods comprised ca. 90% of the diet of bering sea beaked (mesoplodon stejnegeri true) and baird’s beaked (berardius bairdii stejneger) whales (table 2). the diet of sperm whales is ca. 72–96% cephalopods (table 2). santos et al. (2001) reported that 96% (by weight) of prey items in stranded sperm whale stomachs from norwegian waters were gonatus sp. other mammalian predators from the bering sea, such as northern fur seals (callorhinus ursinus l.) and dall’s porpoise (phocoenoides dalli true), have 33–50% of their diets made up of squid (table 2). thickbilled and common murres (uria spp.) off bjørnøya and bleiksøy, norway, have 30% and 40% of their diets represented by squid and g. fabricii (table 2). the percentage occurrence of indigestible cephalopod parts (mostly beaks) and flesh from the stomachs of sampled predators is listed in table 3. these records indicate cephalopod remains, but not the relative proportion table 4 continued location predators cephalopod prey southern greenland greenland halibut (reinhardtius hippoglossoides)m squid tremblay sound, creswell bay narwhal (monodon monoceros)i gonatus sp. uummannaq (north-west greenland) narwhal (monodon monoceros)n gonatus fabricii western alaska beluga whale (delphinapterus leucas)g gonatus sp. octopus sp. within the predators’ natural range harbour seal (phoca vitulina)d,o squid ribbon seal (histriophoca fasciata)d,o squid spotted seal (phoca largha)d,o squid narwhal (monodon monoceros)d,o gonatus fabricii a welch et al. 1992; b gaston 1985; c stewart & stewart 1989; d loeng et al. 2005; e dehn et al. 2007; f haug et al. 2004; g dahl et al. 2000; h hjort & ruud 1929; i laidre et al. 2004; j bjørke 2001; k dommasnes et al. 2001; l hay & mansfield 1989; m woll & gundersen 2004; n cosewic 2004; o tomilin 1967 (1957). arctic ocean cephalopod distribution and predators k. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd214 in the diets. all bottlenose whales (hyperoodon ampullatus forster) sampled around iceland had squid remains in their stomachs, and 92% of narwhals caught off pond inlet in 1978 had g. fabricii parts in their digestive tracts (79% in 1979) (table 2). cephalopods comprised 67–71% of the diet of bearded seals (erignathus barbatus erxleben) from grise fjord (table 2), and 69.4% of the diet was unidentified octopods near barrow, alaska (table 3). of the sperm whales collected off andenes, norway, in 1971, 83% had squid beaks in their stomachs (table 3). more than 50% of the anecdotal accounts of diets of arctic predators list gonatus sp. (likely to be g. fabricii based on locations) in the diets, indicating its importance as a prey species (table 4). discussion recent studies have shown that cephalopods, specifically the high-energy keystone species g. fabricii, are important prey for a variety of arctic predators (frandsen & wieland 2004; chambers & dick 2007). with increasing water fig. 1 circumpolar records of gonatus fabricii. sources: berry (1925); hjort & ruud (1929); grieg (1930) and kubodera & tsuchiya (1993), as cited in cephbase; grimpe (1933); muus (1962); nesis (1965, 2001, 2003 [1971]); young (1973); kristensen (1977, 1982); finley & gibb (1982); wiborg et al. (1982); gaston (1985); sennikov et al. (1989); piatkowski & wieland (1993); barrett et al. (1997); b. bluhm (pers. comm. 2007); zumholz et al. (2007); atlantic reference centre collection; canadian museum of nature collection; atlantic reference centre online database; smithsonian national museum of natural history online database; northwest atlantic fisheries organization (nafo) fishery survey of 2004 (m. treble, pers. comm.); nafo survey of 2007 (m. treble, pers. comm.); raskoff et al. in press; and t.a. dick (unpubl. data). forty-two specimens were collected during the nafo trawl surveys in 2006. they were caught along the west side of baffin bay between depths of 425.5 and 1482.5 m (treble 2007). arctic ocean cephalopod distribution and predatorsk. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 215 temperatures, more temperate species, such as i. illecebrosus and l. forbesi, are likely to become more common, thereby increasing the competition for prey and adding to the predation pressure on such species as g. fabricii (o’dor 1983). it is unknown what impact these potential shifts in predator–prey interactions might have on the overall food web. arctic cephalopod range extensions gonatus fabricii. we extend the range of g. fabricii from that described by clarke (1966). this new distribution includes the eastern siberia sea, the beaufort sea (canada basin) (raskoff et al. in press; b. bluhm, pers. comm. 2007), pond inlet (stomach contents of narwhals) and the most northern canadian arctic location, cape vera (t.a. dick, unpubl. data; fig. 1). although not reported by nesis (2001), specimens from the dolphin and union strait (arc; fig. 1) give validity to nesis’s description of a circumpolar species. discrepancies have been noted between the range described in this study and previously reported distributions, especially from the pacific ocean. other regions of the pacific ocean probably represent a different species of gonatid (wiborg et al. 1982). rossia moelleri. nesis (2001) noted that r. moelleri is not typically found south of 75°n, although a “questionable” specimen from franklin bay was reported. the present range includes specimens collected south of 75°n near cape parry and coronation gulf, and extending into waters around iceland (fig. 4). the range also extends to the interior of frobisher bay and melville island (fig. 4). rossia palpebrosa. with a distribution throughout most of the arctic ocean (nesis, 2001), r. palpebrosa has a similar range to r. moelleri. the present distribution reflects that described by nesis (2001), with the exception of no records from iceland or the danish strait fig. 2 distribution of gonatus fabricii in the western european arctic with reference to potential spawning locations, areas of 500+ juveniles per haul caught between june and august 1978–1981 and a region where 8000 juveniles per haul were recorded in july 1980 (wiborg et al. 1982). for a more accurate representation of the juvenile distribution of g. fabricii, see wiborg et al. (1982: fig. 1). arctic ocean cephalopod distribution and predators k. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd216 (fig. 6). the range is extended in the canadian arctic to hudson strait, the mouth of cumberland sound, frobisher bay, and somerset and ellesmere islands (fig. 6). bathypolypus arcticus. muus’s (2002) re-description of the b. arcticus complex requires most museum specimens to be re-examined and identified under the new criteria. based on current museum records, our map shows a distribution south from hudson strait to frobisher bay, southern davis strait and north to lady ann strait (fig. 7). the species identification of samples collected around the united kingdom, norway and southern greenland are questionable, as they occur in areas of fig. 3 occurrence records of gonatus fabricii specimens, including remains in the stomach contents of predators. sources: berry (1925); hjort & ruud (1929); grieg (1930) and kubodera & tsuchiya (1993), as cited in cephbase; grimpe (1933); muus (1962); nesis (1965, 2001, 2003 [1971]); young (1973); kristensen (1977, 1982); wiborg et al. (1982); finley & gibb 1982; gaston 1985; sennikov et al. (1989); piatkowski & wieland (1993); barrett et al. (1997); b. bluhm (pers. comm. 2007); zumholz et al. (2007); atlantic reference centre collection; canadian museum of nature collection; atlantic reference centre online database; smithsonian national museum of natural history online database; northwest atlantic fisheries organization (nafo) (m. treble pers. comm.); nafo survey of 2007 (m. treble, pers. comm.); raskoff et al. in press; and t.a. dick (unpubl. data). arctic ocean cephalopod distribution and predatorsk. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 217 potential overlap between b. arcticus, b. bairdii and b. pugniger sp. (fig. 7) (muus 2002). a specimen from cape parry (cmnml) (fig. 7) was confirmed as the westernmost canadian distribution of b. arcticus; however, records extend the range further west to point barrow, alaska, and the canada basin (fig. 7). these locations extend the range west from muus’s (2002) original description. only two specimens were recorded by muus (2002) from canadian waters, one from devon island and the other just off the cumberland peninsula, baffin island. the current map extends the species to pond inlet and frobisher bay. our distribution re-affirms o’dor & macalaster’s (1983) and nesis’s (2001) claim of a western canadian distribution. cirroteuthis muelleri. nesis (2001) described c. muelleri as a circumpolar species found in deep water (500– 3786 m), and our range agrees, with the exception of specimens from the shallower laptev sea (fig. 9). additional locations were identified from the canada basin, based on plankton samples and remotely operated vehicle surveys by arcod and the noaa ocean explorer (raskoff et al. in press; b. bluhm, pers. comm. 2007; fig. 9). the greatest number of samples caught in one location (n = 63) were caught in northern baffin bay (fig. 9). additional arctic cephalopod distributions. several other species have been reported from the arctic (table 1), and of these b. bairdii and r. glaucopis were the fig. 4 circumpolar records of rossia moelleri. sources: grieg (1930), as cited in cephbase; grimpe (1933); kondakov (1937); muus (1962); wacasey et al. (1979); atkinson & wacasey (1989); nesis (2001); canadian museum of nature collection; and atlantic reference centre online database. one specimen of r. moelleri was caught between a depth of 139 and 150.5 m from the western side of baffin bay during northwest atlantic fisheries organization trawl surveys in 2006 (treble 2007). arctic ocean cephalopod distribution and predators k. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd218 most abundant (table 1). the remaining species are listed in table 1. predator–prey relationships arctic predators of cephalopods are often large and mobile. consequently, the source of samples collected needs to be considered when designating an “area of interest”. areas with large numbers of recorded specimens may indicate a greater abundance of cephalopods or may be associated with an active sampling programme of a nearby field station or traditional hunting grounds. the latter may also indirectly reflect an abundance of prey in that particular region. fig. 5 circumpolar records of rossia moelleri specimens, including remains in the stomach contents of predators. sources: grieg (1930), as cited in cephbase; grimpe (1933); kondakov (1937); muus (1962); wacasey et al. (1979); atkinson & wacasey (1989); nesis (2001); canadian museum of nature collection; and atlantic reference centre online database. arctic ocean cephalopod distribution and predatorsk. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 219 cape vera and pond inlet are areas where northern fulmars are studied and narwhals are traditionally hunted. records from both locations indicate that more than 100 samples of g. fabricii were collected from individual fulmar and narwhal stomachs (figs. 1, 3). this distribution may indicate areas of greater cephalopod concentrations where predators congregate to feed. however, cephalopod beaks can accumulate in stomachs over time, with unknown expulsion rates (lowry et al. 1986), which could result in an overestimation of predation pressure (santos et al. 2001). arctic predators are also migratory, and beaks collected from a sample from one location may be acquired from a different region. in the case of cape vera, the northern fulmars were believed to not travel great distances to forage, but a recent survey of the area found only a few individuals hunting in the fig. 6 circumpolar records of rossia palpebrosa. sources: grimpe (1933); kondakov (1937); wacasey et al. (1979); nesis (2001); canadian museum of nature collection; and atlantic reference centre online database. seven specimens were collected from the western side of baffin bay during northwest atlantic fisheries organization trawl surveys in 2006. they were all caught between depths of 123 and 611.5 m (treble 2007). arctic ocean cephalopod distribution and predators k. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd220 nearby hell gate polynya, suggesting foraging trips of greater distances (mallory & gilchrist 2005). however, as cape vera is a breeding colony, it is unlikely that the birds would venture too far in search of food while caring for their young. also, beaks may indirectly enter a predator’s stomach when the animal feeds on a teuthophagus predator (santos et al. 2001). increased sample numbers from a region may also reflect an active commercial fishery with a substantial bycatch. large numbers of g. fabricii are reported from trawls along the south-west coast of greenland (fig. 1), and are frequently recovered as bycatch in the shrimp fishery (kristensen 1983; piatkowski & wieland 1993; zumholz & frandsen 2006). similarly, b. arcticus distribution is frequently reported from trawls (stewart et al. 1993) (figs. 7, 8). oceanographic variables and distributions many species of cephalopod have planktonic life stages, and ocean currents influence dispersal and local retention. reports from the norwegian sea (between jan mayen and vesterålen) indicate high densities of cephalopods, particularly g. fabricii, in areas with eddies (figs. 2, 3; wiborg et al. 1982). larval g. fabricii cannot contract mantle muscles to drive active locomotion (e.g., fig. 7 circumpolar records of bathypolypus arcticus. not included is a record (taxonomic information system for the belgian coastal area online database) from the centre of iceland. sources: hoyle (1886), grieg (1930), robson (1931), adam (1939) and macalaster (1976), as cited in cephbase; grimpe (1933); kondakov (1937); muus (1962, 2002); wacasey et al. (1979); finley & gibb (1982); atkinson & wacasey (1989); stewart et al. (1993); nesis (2001); canadian museum of nature collection; smithsonian national museum of natural history online database; northwest atlantic fisheries organization (nafo) survey of 2004 (m. treble, pers. comm.); and nafo survey of 2007 (m. treble, pers. comm.). arctic ocean cephalopod distribution and predatorsk. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 221 nesis, 1965; kristensen, 1983; arkhipkin & bjørke 1999), and, similarly, mature females lose musculature and revert back to a planktonic way of life (e.g., clarke 1966; kristensen 1983; arkhipkin & bjørke 1999). by contrast, b. arcticus and rossia species lack a planktonic stage, and are not greatly influenced by currents (sweeney et al. 1992; wood 2000). depth is another key variable, as c. muelleri is typically limited to deep water regions in the arctic ocean and baffin bay (fig. 9). polynyas, regions with wind-induced upwellings and direct access to sunlight, have increased productivity (brown & nettleship, 1981). the canadian arctic has several polynyas, including the large north water in baffin bay (michel et al. 2006). the distributions of some cephalopod species may correlate with these open water areas. an example is cephalopods from cape parry, a potential “hotspot” affected by the cape bathurst flaw lead (michel et al. 2006). this lead creates higher productivity and, in turn, provides greater quantities of prey for cephalopods. large numbers of b. arcticus were also collected off greenland near the north water polynya. nesis (2003 [1971]) suggested that cephalopods caught in the high arctic through holes in the ice from drifting stations may have been responding to increased light. if this is the case, polynyas are likely to be the areas with most light during the winter months in the arctic ocean, and may explain, at least in part, the occurrences of greater numbers of cephalopods and their predators. fig. 8 circumpolar records of bathypolypus arcticus specimens, including remains in the stomach contents of predators. sources: hoyle (1886), grieg (1930), robson (1931), adam (1939) and macalaster (1976), as cited in cephbase; grimpe (1933); kondakov (1937); muus (1962, 2002); wacasey et al. (1979); finley & gibb (1982); atkinson & wacasey (1989); stewart et al. (1993); nesis (2001); canadian museum of nature collection; smithsonian national museum of natural history online database; northwest atlantic fisheries organization (nafo) survey of 2004 (m. treble, pers. comm.); and nafo survey of 2007 (m. treble, pers. comm.). arctic ocean cephalopod distribution and predators k. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd222 predator–prey distributions relative to ocean variables predators are often reported in areas with an abundance of cephalopods (hjort & ruud, 1929). table 4 lists predators found in the norwegian sea near retention areas with strong circular currents (wiborg et al. 1982; dommasnes et al. 2001), where planktonic cephalopods (e.g., larvae) are likely to become concentrated. narwhals feeding near pond inlet may be responding to greater prey abundance caused by currents in baffin bay and the local polynya (whoi 2006; barber & massom 2007). belugas have also been reported from the amundsen gulf (l. harwood, pers. comm. 2007), which is an area of cephalopod aggregations (figs. 1–10), possibly as a result of eddies formed by the influx of water from the bering sea (whoi 2006) or by the retention from the cape bathurst polynya flaw lead (barber & massom 2007). summary in summary, cephalopods play an important role in arctic food webs, and are highly dependent on oceanographic processes for distribution. further research on the collection of quantitative trawl data in biologically sensitive areas, in areas of active ocean currents and remote regions of the canadian arctic are urgently needed. furthermore, a comprehensive compilation of communityfig. 9 circumpolar records of cirroteuthis muelleri. forty-five individuals were collected from the western side of baffin bay during northwest atlantic fisheries organization (nafo) trawl surveys in 2006. they were collected between the depths of 103 and 1482.5 m (treble 2007). sources: grieg (1930) and robson (1931), as cited in cephbase; grimpe (1933); muus (1962); nesis (1987, 2001); collins (2002); b. bluhm (pers. comm. 2007); raskoff et al. in press; ifremer biocean database 2007; smithsonian national museum of natural history online database; swedish museum of natural history online database; and nafo survey of 2004 (m. treble, pers. comm.). arctic ocean cephalopod distribution and predatorsk. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 223 based data on the diets of the commonly harvested marine predators will substantially increase the knowledge of this important group of invertebrates. equally important is information on the physiological requirements of arctic animals and climate change. portner and farrel (2008) discuss poleward shifts in the geographical distributions of animals, population collapses, changes in seasonal timing of biological events and changes in food-web structure, all of which are influenced by environmental temperatures. cephalopods inhabit both deep and shallow waters, and some of their larvae are dispersed by surface waters, which make them vulnerable to temperature changes at all depths. data are needed on cephalopod optimum temperature ranges and oxygen requirements. these baseline data are essential to clarify the importance and distribution of this nutrient-rich food source in arctic marine food webs in the context of ice loss, warming waters, altered ocean currents, salinity and alien species invasions, including the large cephalopod predators. acknowledgements tad acknowledges financial support from a natural sciences and engineering research council of canada northern research chair, and kg thanks the faculty of science, university of manitoba, for partial financial support through a graduate scholarship. we thank dr. m. papst and m. treble, department of fisheries and oceans, winnipeg, for support and access to trawl data from surveys in the davis strait and baffin bay area. we also thank the reviewers for their helpful and constructive comments, which significantly improved the manuscript. additional thanks go to drs. gretta pecl, clyde roper and michael vecchione for help in obtaining nesis’s translated works. we thank dr. nigmatullin for suggesting some important manuscripts. references academy of natural sciences malacology database. online database accessed through global biodiversity information facility (gbif) data portal at http://data.gbif.org/datasets/ resource/175 on 5 november 2007. arkhipkin a.i. & bjørke h. 1999. ontogenetic changes in morphometric and reproductive indices of the squid gonatus fabricii (oegopsida, gonatidae) in the norwegian sea. polar biology 22, 357–365. atlantic reference centre. online database accessed through global biodiversity information facility (gbif) data portal at http://data.gbif.org/datasets/resource/341 on 5 november 2007. atkinson e.g. & wacasey j.w. 1989. benthic invertebrates collected from the western canadian arctic, 1951 to 1985. canadian data report of fisheries and aquatic sciences 745. winnipeg: department of fisheries and the environment, fisheries and marine service. fig. 10 canadian records of unidentified cephalopods. not included are a record of an unidentified cephalopod from central norway and one from alaska (coordinates not accurate). sources: hay & mansfield (1989); welch et al. (1992); stewart et al. (1993); dehn et al. (2007); l. harwood (pers. comm. 2007); smithsonian national museum of natural history online database; northwest atlantic fisheries organization (nafo) survey of 2004 (m. treble, pers. comm.); nafo survey of 2007 (m. treble, pers. comm.); and t.a. dick (unpubl. data). arctic ocean cephalopod distribution and predators k. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd224 http://data.gbif.org/datasets http://data.gbif.org/datasets/resource/341 barber d.g. & massom r.a. 2007. the role of sea ice in bipolar polynya processes. in w.o. smith jr. & d.g. barber (eds.): polynyas: windows into polar oceans. pp. 1–43. amsterdam: elsevier. barrett r.t., bakken v. & krasnov j.v. 1997. the diets of common and brünnich’s guillemots uria aalge and u. lomvia in the barents sea region. polar research 16, 73–84. berry s.s. 1925. the cephalopoda collected by the canadian arctic expedition, 1913–18. report of the canadian arctic expedition 1913–18 8b, 3–8. bjørke h. 2001. predators of the squid gonatus fabricii (lichtenstein) in the norwegian sea. fisheries research 52, 113–120. brown r.g.b. & nettleship d.n. 1981. the biological significance of polynyas to arctic colonial seabirds. in i. stirling et al. (eds): polynyas in the canadian arctic. canadian wildlife service occasional paper 45. pp. 59–65. ottawa: canadian wildlife service. chambers c.a. & dick t.a. 2007. using environmental variables to predict the structure of deep-sea arctic fish communities: implications for food web construction. arctic, antarctic and alpine research 39, 2–8. cephbase. national resource center for cephalopods, galveston, tx. online database accessed on the internet at http://www.cephbase.utmb.edu/ in december 2007. clarke m.r. 1966. a review of the systematics and ecology of oceanic squids. advances in marine biology 4, 91–300. collins m.a. 2002. cirrate octopods from greenland and iceland waters. journal of the marine biological association of the united kingdom 82, 1035–1036. collins m.a. 2005. opisthoteuthis borealis: a new species of cirrate octopod from greenland waters. journal of the marine biological association of the united kingdom 85, 1475–1479. cosewic (committee on the status of endangered wildlife in canada) 2004. cosewic assessment and update status report on the monodon monoceros in canada. ottawa: committee on the status of endangered wildlife in canada. dahl t.m., lydersen c., kovacs k.m., falk-petersen s., sargent j., gjertz i. & gulliksen b. 2000. fatty acid composition of the blubber in white whales (delphinapterus leucas). polar biology 23, 401–409. dawe e.g., bowering w.r. & joy j.b. 1998. predominance of squid (gonatus spp.) in the diet of greenland halibut (reinhardtius hippoglossoides) on the deep slope of the northeast newfoundland continental shelf. fisheries research 36, 267–273. dehn l.-a., sheffield g.g., follmann e.h., duffy l.k., thomas d.l. & o’hara r.m. 2007. feeding ecology of phocid seals and some walrus in the alaskan and canadian arctic as determined by stomach contents and stable isotope analysis. polar biology 30, 167–181. dommasnes a., christensen v., ellertsen b., kvamme c., melle w., nøttestad l., pedersen t., tjelmeland s. & zeller d. 2001. an ecopath model for the norwegian sea and barents sea. in s. guénette et al. (eds.): fisheries impacts on north atlantic ecosystems: models and analyses. fisheries centre research 9, 213–240. finley k.j. & evans c.r. 1983. summer diet of the bearded seal (erignathus barbatus) in the canadian high arctic. arctic 36, 82–89. finley k.j. & gibb e.j. 1982. summer diet of the narwhal (monodon monoceros) in pond inlet, northern baffin island. canadian journal of zoology 60, 3353–3363. frandsen r.p. & wieland k. 2004. cephalopods in greenland waters. technical report 57. pinngortitaleriffik: greenland institute of natural resources. gaston a.j. 1985. the diet of thick-billed murre chicks in the eastern canadian arctic. the auk 102, 727–734. geonames. online database accessed on the internet at http://www.geonames.org in december 2007. grimpe g. 1933. die cephalopodan des arktischen gebietes. (cephalopods of the arctic.) fauna arctica 6, 491–514. haug r., nilssen k.t. & lindblom l. 2004. feeding habits of harp and hooded seals in drift ice waters along the east coast of greenland in summer and winter. polar research 23, 35–42. hay k.a. & mansfield a.w. 1989. narwhal, monodon monoceros linnaeus 1758. in s.h. ridgeway & r.j. harrison (eds.): handbook of marine mammals. vol. 4. river dolphins and the larger toothed whales. pp. 145–176. london: academic press. historical benthic dredge samples from the southern baltic and the north sea. online database accessed through global biodiversity information facility (gbif) data portal at http://data.gbif/org/datasets/resource/407 on 5 november 2007. hjort j. & ruud j.t. 1929. whaling and fishing in the north atlantic. in j. hjort & j.t. ruud: whales and plankton in the north atlantic. a contribution to the work of the whaling committee and of the north eastern area committee. rapports et procès-verbaux des réunions conseil permanent international pour l’exploration de la mer 56. pp. 1–123. copenhagen: conseil permanent international pour l’exploration de la mer. hooker s.k., iverson s.j., ostrom p. & smith s.c. 2001. diet of northern bottlenose whales inferred from fatty-acid and stable isotope analyses of biopsy samples. canadian journal of zoology 79, 1442–1454. ifremer biocean, deep sea benthic fauna. online database accessed through global biodiversity information facility (gbif) data portal at http://data.gbif.org/datasets/ resource/358 on 5 november 2007. integrated taxonomic information system. accessed on the internet at http://www.itis.gov/ in 2008. kondakov n.n. 1937. golovonogie molljuski (cephalopoda) karskogo morja. (the cephalopoda of the kara sea.) transactions of the arctic institute 1, 61–67. kristensen t.k. 1977. hatching, growth, and distribution of juvenile gonatus fabricii (mollusca: cephalopoda) in greenland waters. astarte 10, 21–28. arctic ocean cephalopod distribution and predatorsk. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 225 http://www.cephbase.utmb.edu http://www.geonames.org http://data.gbif/org/datasets/resource/407 http://data.gbif.org/datasets http://www.itis.gov kristensen t.k. 1982. multivariate statistical analysis of geographic variation in the squid gonatus fabricii (lichtenstein, 1818) (mollusca: cephalopoda). malacologia 22, 581–586. kristensen t.k. 1983. gonatus fabricii. in p.r. boyle (ed.): cephalopod life cycles. vol. 1. species accounts. pp. 159–173. london: academic press. laidre k.l., heide-jørgensen m.p., jørgensen o.a. & treble m.a. 2004. deep-ocean predation by a high arctic cetacean. ices journal of marine science 61, 430–440. loeng h., brander k., carmack e., denisenko s., drinkwater k., hansen b., kovacs k., livingston p., mclaughlin f. & sakshaug e. 2005. marine systems. in c. symon et al. (eds.): arctic climate impact assessment. pp. 439–538. cambridge: cambridge university press. lowry l.f., frost k.j. & seaman g.a. 1986. investigations of belukha whales in coastal waters of western and northern alaska, iii: food habits. fairbanks: alaska department of fish and game. mallory m.l. & gilchrist h.g. 2005. marine birds of the hell gate polynya, nunavut, canada. polar research 24, 87–93. mercer m.c. 1968. a synopsis of the recent cephalopoda of canada. in: proceedings of the symposium on mollusca held at cochin from january 12 to 16, 1968. part i. marine biological association of india symposium series 3. pp. 265–276. madapam: marine biological association of india. michel c., ingram r.g. & harris l.r. 2006. variability in oceanographic and ecological processes in the canadian arctic archipelago. progress in oceanography 71, 379–401. muus b.j. 1962. cephalopoda. the godthaab expedition 1928. meddelelser om grønland 81(5). copenhagen: committee on scientific research in greenland. muus b.j. 2002. the bathypolypus–benthoctopus problem of the north atlantic (octopodidae, cephalopoda). malacologia 44, 175–222. nesis k.n. 1965. the distribution and nutrition of young squid gonatus fabricii (licht.) in the labrador sea and the norwegian sea. oceanology 5, 102–108. nesis k.n. 1987. golovonogie molljuski severnogo ledovitogo okeana i ego morej. (cephalopod molluscs of the arctic ocean and its seas.) in a.i. kafanov (ed.): fauna i raspredelenie molljuskov: severnaja pacifika i poljarnyj bassejn. (fauna and distribution of molluscs: north pacific and arctic basin.) pp. 115–136. vladivostok: far eastern scientific center of the ussr academy of sciences. nesis k.n. 2001.west-arctic and east-arctic distributional ranges of cephalopods. sarsia 86, 1–11. nesis k.n. 2003 (1971). squid gonatus fabricii (licht.) in the center of the arctic ocean. in m.j. sweeney (ed.): english translations of selected publications on cephalopods by kir n. nesis. vol. 1. part 1. pp. 71–85. washington, d.c.: smithsonian institution libraries. nesis k.n. 2003 (1989). cephalopods from open waters of the okhotsk sea: general distribution and zoogeography. in m.j. sweeney (ed.): english translations of selected publications on cephalopods by kir n. nesis. vol. 1. part 2. 763–772. washington, d.c.: smithsonian institution libraries. nesis k.n., amelekhina a.m., boltachev a.r. & shevtsov g.a. 2003 (1985). records of giant squid of the genus architeuthis in the north pacific and south atlantic. in m.j. sweeney (ed.): english translations of selected publications on cephalopods by kir n. nesis. vol. 1. part 2. pp. 685–697. washington, d.c.: smithsonian institution libraries. north pacific groundfish observer. online database accessed through global biodiversity information facility (gbif) data portal at http://data.gbif.org/datasets/resource/331 on 5 november 2007. o’dor r. 1983. illex illecebrosus. in p.r. boyle (ed.): cephalopod life cycles. vol. 1. species accounts. pp. 175–199. london: academic press. o’dor r. & macalaster e. 1983. bathypolypus arcticus. in p.r. boyle (ed.): cephalopod life cycles. vol. 1. species accounts. pp. 401–410. london: academic press. orr d.c. & bowering w.r. 1997. a multivariate analysis of food and feeding trends among greenland halibut (reinhardtius hippoglossoides) sampled in davis strait, during 1986. ices journal of marine science 54, 819–829. perez m.a. 1990. review of marine mammal population and prey information for bering sea ecosystem studies. noaa technical memorandum nmfs f/nwc-186. washington, d.c.: us department of commerce. piatkowski u. & wieland k. 1993. the boreoatlantic gonate squid gonatus fabricii: distribution and size off west greenland in summer 1989 and in summer and autumn 1990. aquatic living resource 6, 109–114. portner h.-o. & farrel a.p. 2008. physiology and climate change. science 322, 690–692. raskoff k.a., hopcroft r.r., kosobokova k.n., purcell j.e & youngbluth m.j. in press. jellies under ice: rov observations from the arctic 2005 hidden ocean expedition. deep-sea research ii. santos m.b., clarke m.r. & pierce g.j. 2001. assessing the importance of cephalopods in the diets of marine mammals and other top predators: problems and solutions. fisheries research 52, 121–139. sennikov a.m., mukhin s.g. & bliznichenko t.e. 1989. distribution and trophic importance of juvenile squid (gonatus fabricii lichtenstein) in the norwegian and barents seas in 1986–1988. ices cm 1989/k: 15. copenhagen: international council for the exploration of the sea. smithsonian national museum of natural history invertebrate zoology collections. online database accessed through global biodiversity information facility (gbif) data portal at http://data.gbif.org/datasets/resource/1834 on 22 may 2008. stewart d.b., ratynski r.a., bernier l.m.j. & ramsey d.j. 1993. a fishery development strategy for the canadian beaufort sea–amundsen gulf area. canadian technical report of fisheries and aquatic sciences 1910. winnipeg: department of fisheries and oceans. stewart b.e. & stewart e.a. 1989. delphinapterus leucas. mammalian species 336. american society of mammalogists. arctic ocean cephalopod distribution and predators k. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd226 http://data.gbif.org/datasets/resource/331 http://data.gbif.org/datasets/resource/1834 swedish museum of natural history: invertebrates. online database accessed through global biodiversity information facility (gbif) data portal at http://data.gbif.org/datasets/ resource/1027 on 5 november 2007. sweeney m.j., roper c.f.e., mangold k.m., clarke m.r. & boletzky s.v. (eds.) 1992. “larval” and juvenile cephalopods: a manual for their identification. smithsonian contributions to zoology 513. washington, d.c.: smithsonian institution press. taxonomic information system for the belgian coastal area. online database accessed through global biodiversity information facility (gbif) data portal at http:// data.gbif.org/datasets/resource/361 on 22 may 2008. tomilin a.g. 1967 (1957). mammals of the u.s.s.r. and adjacent countries. vol. 9. cetacea. jerusalem: israel program for scientific translations. treble m.a. 2007. analysis of data from the 2006 trawl surveys of nafo division oa. scientific council meeting. nafo scr doc. 07/41. dartmouth, ns: northwest atlantic fisheries organization. wacasey j.w., atkinson e.g. & glasspoole l. 1979. zoobenthos data from upper frobisher bay 1967–1973. canadian data report on fisheries and aquatic science 64. ste. anne de bellevue, qc: department of fisheries and oceans. welch h.e., bergmann m.a., siferd t.d., martin k.a., curtis m.f., crawford r.e., conover r.j. & hop h. 1992. energy flow through the marine ecosystem of the lancaster sound region, arctic canada. arctic 45, 343–357. whoi (woods hole oceanographic institution) 2006. polar discovery. arctic ocean circulation. accessed on the internet at http://polardiscovery.whoi.edu/arctic/ circulation.html on 7 january 2008. wiborg k.f., gjøsæter j. & beck i.m. 1982. the squid gonatus fabricii: investigations in the norwegian sea and western barents sea. ices cm 1984/k: 19. copenhagen: international council for the exploration of the sea. woll a.k. & gundersen a.c. 2004. diet composition and intra-specific competition of young greenland halibut around southern greenland. journal of sea research 51, 243–249. wood j.b. 2000. the natural history of bathypolypus arcticus (prosch), a deep-sea octopus. phd thesis, dalhousie university. young r.e 1973. evidence for spawning by gonatus sp. (cephalopoda: teuthoidea) in the high arctic ocean. nautilus 87, 53–58. zumholz k. & frandsen r.p. 2006. new information on the life history of cephalopods off west greenland. polar biology 29, 169–178. zumholz k., klügel a., hansteen t. & piatkowski u. 2007. statolith microchemistry traces of the environmental history of the boreoatlantic armhook squid gonatus fabricii. marine ecology progress series 333, 195–204. arctic ocean cephalopod distribution and predatorsk. gardiner & t.a. dick polar research 29 2010 209–227 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 227 http://data.gbif.org/datasets http://data.gbif.org/datasets/resource/361 http://data.gbif.org/datasets/resource/361 http://polardiscovery.whoi.edu/arctic research note moulting juvenile male southern elephant seals mirounga zeonina (l.) at hannah point, walker bay, livingston island, south shetland islands elizabeth cruwys and pamela b . davis cruwys, e . & davis, p . b . 1995: moulting juvenile male southern elephant seals mirounga leoniria ( l . ) at hannah point, walker bay, livingston island, south shetland islands. polar research i 4 ( 3 ) , 329-333. southern elephant seals mirounga leonina (l.) were counted at seventeen discrete moulting sites at hannah point, walker bay o n livingston island in the south shetland islands between 2 january and 16 february 1994. the physical characteristics of each moulting site were assessed. counts through 46 consecutive days demonstrated that the number of juvenile males in dry moulting sites increased as the muddy wallows were gradually abandoned. this pattern of behaviour is similar to the pattern described for other sexand age groups ( e . g . adult females) in previous studies. e . cruwys, department of zoology, university of cambridge, new museum site, downing street, cambridge cb2 3 n , uk; p . b . dauis, scott polar research imtiture, university of cambridge, lensfield road, cambridge cb2 ier, u k . .a ~ * ~ p o ~ a r ~ ~ ~ ~ ‘ ’ introduction all pinnipeds undergo an annual moulting process (scheffer 1958; king 1983). elephant seals in particular are especially notable because of the sloughing off of sheets of cornified epidermis with old hairs (matthews 1929; laws 1956; carrick et al. 1962). during this energy-demanding period (fay & ray 1968; boyd et al. 1994), pinnipeds often exhibit listless and ill-tempered behaviour (rand 1967; wartzok 1991; cruwys & weinstein 1993). this is primarily due to the physiological disturbances which occur during the moult (such as the high peripheral temperature required, reduction in resting metabolic rate, and the fasting or near-fasting conditions observed by some pin nipeds (boyd et al. 1993). southern elephant seals mirounga leonina (l.) remain ashore for up to 56 days while old hair and skin sloughs away and new hair begins to grow (laws 1956). mature adult males tend to haul out for a longer period than younger males and females (laws 1956; ling & bryden 1981). the timing of the moult in southern elephant seals thus varies among populations and age groups. adult males tend to moult later than females and juveniles, normally hauling out between the beginning of february and mid-may; cows and juveniles typically moult between november and the end of march, although juveniles tend to arrive and leave earlier than females (hindell & burton 1988; le boeuf & laws 1994). according to le boeuf & laws (1994), juvenile elephant seals begin to arrive at signy island and mac quarie island to moult in mid-november. a peak in numbers is reached in mid-december, and most seals have left by late january. it has been noted that when they first arrive at a beach, southern elephant seals spend some time changing positions until a suitable moulting site (i.e. a location where a number of seals con gregate) is found (matthews 1929; laws 1956; carrick et al. 1962). the selection by southern elephant seals of specific sites for moulting and, later, at which to grow new hair, is determined by the physical characteristics of each site. there are two extremes of moulting sites: (1) a “wallow” which is a swampy morass of mud and water, sometimes more than two metres deep, described by matthew (1929) and laws (1956); and (2) a “dry site” which is a well-drained area free of mud. in a study by fedak et al. (1994), twenty lactating female southern elephant seals were 330 e. cruwys & p. b. davis marked or radio-tagged at husvik in south georgia. and then monitored during moult. i t was found that after making landfall, the seals often re-entered the water and sought another moulting site, sometimes many kilometres distant. they remained mobile for several days before settling in a moulting site at some distance from the sea. once new hair growth begins. an animal often moves to a dry site (fedak et al. 1994). tierney (1977), while observing southern elephant seals at the vestfold hills in antarctica. also noted that seals moved between sites while moulting. in order to test whether juvenile southern elephant seals follow the pattern observed in females by fedak e t al. (1994). seals were observed during the moulting period at hannah point. walker bay, livingston island, south shetland islands between 2 january and 16 february 1994. study area description h a n n a h point at walker bay (62"39's, 60"38'w) is located o n t h e southern central coast of livingston island in the south shetland islands (fig. 1a). during most of the austral summer it is free of snow and ice, with t h e exception of small chunks of ice that were abraded from nearby glaciers by wave action a n d washed up onto the shore. h a n n a h point is a spit of land 1 . 6 k m long cxw a l k e r b a y a 500 f i g . 1 . study area. a . the south shetland islands, showing the location of hannah point in walker bay. livingston island. b. the position of the seventeen moulting sites (a-k) in the hannah pomt area. at locations a , b. g . i , j. and k there were two moulting sites. the shaded areas represent land covered by glacier: the unshaded areas represent ice free beaches. triangles represent outcrops of rock and boulders. moulting juuenile male souihern elephant seals 331 during the period of observation, most seals observed were juvenile males. following the classification of laws (1956), these were class 111, “medium size, aged from three to five years, usually sexually mature, but not large enough to take part in the activities of the breeding rooker ies”, and class iv, “small and from one to three years old” (laws 1956, p. 6). adult females began to arrive mid-january. but numbers remained low throughout the observation period. only juvenile males were included in this study, partly because they were the most numerous, and partly so as not t o mix data for the sexes. with a ridge about 100 m high running nw to se. the terrain is characterised by predominantly hard-packed sand with some moss beds, although the extreme southwestern area comprises flat rocks and stony beaches. beaches and tussocky grass are the preferred haul-out sites of southern elephant seals (ling & bryden 198l), and although hannah point has no tussock grass, there are abundant flat expanses of sand protected from off-shore or on-shore winds by outcrops of rock. in the present study, moulting sites were observed along the whole length of hannah point. materials and methods southern elephant seals were counted con currently by three independent observers on 46 consecutive days between 8 a.m. and 10 a.m. photographs were taken that allowed the stage of the moult process to be determined using the criteria established by carrick et al. (1962). these are (1) pre-moult, during which changes in location may be made (duration: 9 to 26 days); (2) coat shedding, which lasts 9 to 28 days in immature and sub-adult bulls; and (3) post-moult, which lasts up to 43 days in bulls less than eight years old, and during which the seals move from site to site. the precise location and geographical characteristics of each moulting site were also recorded. results and discussion the number of juvenile male seals at the study site dropped from 339 on 2 january to 90 on 16 february 1994, with a peak of 371 on 3 january. the seals gathered into seventeen discrete moult ing sites at eleven different locations (fig. 1b). at six locations (a, b, g , i , j , and k ) , two pods of seals were within ten metres or less of each other and, with the exception of moulting site g, occupied identical terrain; seals were observed frequently moving from one to the other. or occu pying the area between them. these six locations where seals moved from one part of the site to another are indicated by the addition of lower case letters (aa, ab, ba, bb. etc.). nine moulting distribution of seals according to site type 22s 200 175 150 2 125 --tdry sites r n l. :1m 5 7s a z 50 25 0 f i g . 2. the number of seals decreasing in wallows and e a ~ m q ~ q ~ ~ o n a w ~ o c m n ~ n = ~ ~ 2 n p i n p j n m increasing in dry sites between 2 january and 16 february at n v hannah point. date 332 e . cruwvs & p. b. davis table i physical characteristics of the 17 moulting sites at hannah point. livingston island, south shetland islands moulting distance wallow 01 site ground cover from sea dry site aa and ah ba and bb c d e f g a gh h ia and i b ja and j h ka and kh waterlogged moss, pools of hater sand with pools of water flat rocks and sand: pools of water compacted sand and copper breccia sand and shale compacted sand pebble beach (dry) pebhle beach (with puddleal sand u i t h boulder, sand uirh boulders flat rocka sand w i t h boulders 50 m 50 m 5 m 50 m 5 m 10 m 20 m 10 m 70 ni 1 0 m 2-5 m 5 m wallow wallow wallou dry site dry site dry site dry site wallow dry site dry site dry site wallow notes and period of occupation ~ ~~ at least two seals were usually submerged in the pools of water that were associated with this wallow. abandoned after 24 january. means of 50 seals occurred between 1 1 and 16 january. nearby rock outcrop provided no shelter from the prevailing winds. abandoned after 4 january. 22 seals were counted on 2 january. after which numbers declincd. abandoned after 6 february. between 2-8 january, a mean of 82 seals was recorded daily. juvenile seals were also observed outside the perimeter of the site. a pathway was worn from site d to site e below. con tinuously occupied. numbers ranged between 3 and 17 throughout the entire period a pathway led from the sea to the moulting site avoiding the rocks. continuously occupied. between 5-8 seals were counted daily before 16 january: between 10 and 20 seals daily after 16 january. continuously occupied. numbers steadily increased until 27 january when 71 seals were counted. both sites were located in a cove approximately 20 ni wide surrounded by cliffs 5 m high. ga was continuously occupied. peaks of 45 seals (18 january) and 41 seals (6 february) were recorded. g b abandoned after 5 february. peak of 20 seals on 29 january. after which numbers declined. located on the crest of a gentle slope continuously occu pied. means of 23 seals between 21 and 28 february. after which numbers slowly declined still 8 seals on 16 february. continuously occupied. lou, numbers until 28 january; peak of 54 seals on 2 february. the two wallows were beparated by a rock approximately 40 m high. continuously occupied. numbers between 5 and 40 until 29 january; peak of 52 seals on 30 january. abandoned after 2 february. 52 seals on 2 january. 24 on 1 january. 44 on 7 january; decline after 8 january. the lower case letters indicate sites compo5r.d of two parts where seal, were observed moving from one part to the other sites ( d . e. f. g a . h. ia. i b , j a and j b ) were occupied continuously for the whole study period. while the remaining eight moulting sites ( a a . a b . ba. bb. c. g b , ka and kb) were abandoned permanently by 6 february. table 1 lists each moulting site with its physical characteristics. whether a wallow or a dry site. and its distance from the sea. fig. 2 gives the distribution of juvenile male seals when the sites are categorised by type into wallows and dry sites. the wallows had 221 juv enile males on 2 january, compared t o 89 in the dry sites. (of the remaining 29, 19 were hauled out away from the moulting sites either moving from o n e site to another. or from the sea to a moulting site a n d ten were in the water). t h e numbers of juvenile males in t h e wallows showed a steady decrease while the numbers of seals in the dry sites rose until a peak of 202 seals on 2 february. after which they t o o began to decline. this indicated a definite move from o n e type of moulting site to another. subjective observations suggested that competition for places in the middle of the wallows was intense and that these were usually occupied by larger animals. photo graphs indicated that seals at t h e dry sites, especially towards the end of january, were in the latter stages of coat shedding or in the post moult phase. photographs also showed that dry sites were less tightly packed than wallows, and moulting juvenile male southern elephant seals 333 that there was a great number of seals peripheral to the dry sites (i.e. that had been part of the pod but had moved away). juvenile males were still present at hannah point on 16 february, which may have been a result of unusual weather conditions reported in the 1993/4 season (cruwys & davis 1994). the juvenile male southern elephant seals at hannah point followed the basic pattern noted by fedak et al. (1994); numbers in the wallows were higher earlier in the season (fig. 2 ) and were abandoned when most seals were at the end of the coat-shedding phase, or entering the post moult phase. reasons for this behaviour possibly relate to the thermoregulatory requirements associated with moulting (laws 1956; boyd et al. 1993). energy expenditure on moult has been estimated at 2.4 times the standard metabolic rate (boyd et al. 1994), and it is clearly advantageous for seals to conserve heat by lying as closely to other animals as possible. the implication is that wallows enable the seals to maintain higher skin temperatures with less energy expenditure than is possible in dry sites. when the coat-shedding phase is complete, the seals no longer need to maintain high skin temperatures and move to dry sites where conditions are more favourable for new hair growth. conclusions the data indicate that there is a general move from wallows to dry sites as the moult progresses. thus the movements of the adult female southern elephant seals monitored by fedak et al. (1994) correspond with the movements of the juvenile males at hannah point. the largest concen trations of seals occurred initially in wallows that were abandoned after 6 february. numbers in dry sites increased throughout january. and these sites were still occupied on 16 february. these are tentative conclusions based on data from a single season, and more research is necessary to ascertain the precise movements of individual seals from site to site and within wallows. acknowledgements. -this research was funded by the jephcott charitable trust, the foreign and commonwealth office, and the trans-antarctic association. we thank b. stonehouse for providing us with the opportunity to conduct this research, and b. riffenburgh, g. marshall and s. wells for helping with data collection. additional thanks to g. marshall for producing the maps. and to the two anonymous referees for constructive comments on the manuscript. references boyd, i. l., arnbom, t. a . & fedak, m. a . 1993: water flux, body composition and metabolic rate during moult in female southern elephant seals (mirounga leonina). physiol. zool. 66, 43-60. boyd, i. l . , arnbom, t. a . & fedak, m. a . 1994: biomass and energy consumption of the south georgia population of southern elephant seals. pp. 9&117 in le boeuf, b . j. & laws, r . m. (eds): elephant seals: popiilation ecology, behaviour and physiologv. university of california press, berkeley. carrick, r., csordas, s. e., ingham, s. e. & keith, k. 1962: studies on the southern elephant seal, mirounga leonina ( l . ) . 111. the annual cycle in relation to age and sex. csiro wildlife res. 7(2), 119-160. cruwys, e . & davis. p. b. 1994: southern elephant seal num bers during moult on livingston island, south shetland islands. polar rec. 30(175), 313-314. cruwys, e. & weinstein, d. 1993: aerial survey of walrus haul out sites in west spitsbergen and moffen. polar rec. 29(169), 5 5 5 8 . fay, f. h. & ray, g. c. 1968: influence of climate on the distribution of walruses, odobenus rosmarus [linneaus]. i. evidence from thermoregulatory behaviour. zoologica s-7. 1-18. fedak, m . a . , arnbom, t. a . , mcconnell. b. j.. chambers, c., boyd, i. l . , harwood, j. & mccann, t. s. 1994: expen diture, investment, and acquisition of energy in southern elephant seals. pp. 354-373 in le boeuf, b. j . & laws. r. m. (eds): elephant seals: population ecoiog)i, behaoiour and physiology. university of california press, berkeley. hindell, m. a . & burton, h . r. 1988: seasonal haul-out patterns of the southern elephant seal (mirounga leonina). at macquarie island. j . mammal. 69(1), 81-88. king, j . e. 1983: seals of the world. 2nd edition. oxford university press and the british museum (natural history), oxford and london. 240 pp. laws, r. m. 1956: the elephant seal (mirounga leonina linn.). 11. general, social and reproductive behaviour. falkland islands dependencies survey scientific reports 13. 88 pp. le boeuf. b . j. & laws, r . m. 1994: elephant seals: a n introduction t o the genus. pp. 1-26 in le boeuf, b . j . & laws, r. m. (eds): elephant seals: population ecology, behauiour and physiology. university of california press, berkeley. ling, j. k. & bryden, m . 1981: southern elephant seal. pp. 297-327 in ridgway, s. h . &harrison, r . j. (eds). handbook of marine mammals. academic press, london. matthews, l. h . 1929: the natural history of the elephant seal with notes on other seals found at south georgia. discouery rep. 1 . 233-256. rand, r. w. 1967: the cape fur seal (arcrocephalus pusrllus) 3. general behaviour on land and at sea. republic of south africa, department of commerce and industries, division of sea fisheries, investigative report 21. scheffer, v. b . 1958: seals, sealions and walruses: a retww of the pinnipedia. stanford university press and oxford university press, stanford and london. 179 pp. tierney, t . j . 1977: the southern elephant seal, mirounga leonina (l.), in the vestfold hills, antarctica. aust. wildlife res. 4 , 1 3 2 4 . wartzok, d. 1991: physiology of behaviour in pinnipeds. pp. 236-299 in renouf, d . (ed): the behauiour of pinnipeds. chapman and hall, london. no job name neoproterozoic metamorphic evolution of the isbjørnhamna group rocks from south-western svalbardpor_186 250..264 jaroslaw majka,1 jerzy czerny,2 stanislaw mazur,3 daniel k. holm4 & maciej manecki2 1 department of earth sciences, uppsala university, villavägen 16, se-75236 uppsala, sweden 2 department of mineralogy, petrography and geochemistry, agh–university of science and technology, 30 mickiewicza av., pl-30059 kraków, poland 3 getech, kitson house, elmete hall, elmete lane, leeds, ls8 2lj, uk 4 department of geology, kent state university, kent, oh 44242, usa abstract a metamorphosed volcano-sedimentary complex constitutes the caledonian basement in the south-western part of wedel jarlsberg land, svalbard. field, textural and previous thermochronologic data indicate a weak, localized metamorphic caledonian overprint (m2). deformed m1 isograds and variation in pressure–temperature estimates indicate a pervasive neoproterozoic amphibolite-facies metamorphism that pre-dates large-scale caledonian age folding. garnet–biotite and garnet–al silicate–plagioclase (gasp) geothermobarometry of the isbjørnhamna group mica schists, and their comparison with the k2o–feo–mgo–al2o3–sio2–h2o (kfmash) petrogenetic grid, indicates a peak pressure of ca. 11 kbar, and a peak temperature of ca. 670°c during m1 metamorphism. a cooling rate of ca. 5°c my-1 is estimated on the basis of geothermobarometry and the available u–th–total pb and ar–ar data. keywords caledonides; geothermobarometry; metapelites; neoproterozoic; spitsbergen. correspondence jaroslaw majka, department of earth sciences, uppsala university, villavägen 16, se-75236 uppsala, sweden. e-mail: jaroslaw.majka@geo.uu.se doi:10.1111/j.1751-8369.2010.00186.x southern wedel jarlsberg land (fig. 1) uniquely preserves a record of neoproterozoic metamorphism on spitsbergen, svalbard. in situ uranium–thorium–lead electron microprobe (u–th–pb emp) ages of metamorphic monazites from a proterozoic volcano-sedimentary complex date amphibolite-grade metamorphism at ca. 643 mya (majka et al. 2008). the northern extent of this neoproterozoic metamorphism is bounded by the vimsodden–kosibapasset zone (vkz), which is a major strike–slip shear zone with sinistral kinematics (fig. 2; mazur et al. 2009). the vkz separates the neoproterozoic metamorphic complex from the remaining part of the south-western terranes of svalbard, which were subjected to younger, early palaeozoic metamorphism (gee & tebenkov 2004; czerny et al. 2010). the occurrence of a neoproterozoic metamorphic domain in south-western spitsbergen has important bearing on terrane concepts for svalbard construction in general, and specifically for its proposed correlation with the timanide metamorphic belt of north-eastern europe (mazur et al. 2009). a better understanding of the nature and extent of neoproterozoic metamorphism and associated pervasive deformation, compared with earlier reports (smulikowski 1965; czerny et al. 1993; majka et al. 2004), is an essential prerequisite for testing between, and refining, the tectonic models proposed for this region. in this study we: (1) quantify the peak pressure and temperature conditions for neoproterozoic metamorphism; (2) verify the correlation between the peak of metamorphism and the pervasive deformational fabric; (3) define zones of progressive metamorphism and the relationship between isograds and major tectonic structures; and (4) constrain the cooling history of this neoproterozoic complex. our study is based on extensive fieldwork supported by results of microstructural analysis and geothermobarometric calculations. geological setting the south-western part of spitsbergen island exposes an elongate north–south trending metamorphic basement exhumed within the axial zone of an early palaeogene fold-and-thrust belt (e.g., lowell 1972; dallmann et al. 1993; braathen et al. 1995; bergh et al. 1997). this elevated basement high consists of precambrian to early palaeozoic rocks, the deformation and metamorphism of which were originally ascribed solely to the caledonian orogeny (e.g., holtedahl 1926; ohta 1982; harland 1985; harland et al. 1992). however, the occurrence of regionally extensive unconformities that are polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd250 mailto:majka@geo.uu.se associated with metamorphic and lithological contrasts (e.g., sandford 1956; krasil’ščikov 1979; birkenmajer 1975; bjørnerud 1990) and geochronological studies both provide evidence that the caledonian basement includes proterozoic crustal domains juxtaposed by early palaeozoic tectonic events (e.g., peucat et al. 1989; balashov et al. 1995; gee et al. 1995; hellman et al. 1997; johansson et al. 2004; pettersson et al. 2009). these domains, together with their sedimentary cover, are interpreted to be individual tectonostratigraphic terranes assembled during the caledonian orogeny (e.g., harland 1972; harland & gayer 1972; gee & page 1994). based on important contrasts in stratigraphy, structural development and tectonothermal evolution, the caledonian rocks of svalbard have been divided into eastern, northwestern and south-western terranes (fig. 1; gee 1986; gee & page 1994; gee & tebenkov 2004). north of isfjorden, the south-western terranes of svalbard include a blueschist–eclogite allochthon known as the vestgötabreen complex (e.g. ohta 1979) that yielded argon-40 (40ar)–argon-39 (39ar) mineral cooling ages of ca. 460 my (dallmeyer et al. 1990). the complex is non-conformably overlain by middle ordovician conglomerates and limestones (armstrong et al. 1986), succeeded by late ordovician to early silurian turbidites (scrutton et al. 1976). the metamorphic basement, together with its early palaeozoic cover, is thrust over a succession of diamictites of inferred vendian age (gee & tebenkov 2004). to the south of isfjorden, the southwestern terranes consist of a mesoto neoproterozoic fig. 1 geological sketch map of the svalbard archipelago (modified from gee & tebenkov 2004). neoproterozoic metamorphism in southern svalbardj. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 251 metamorphic complex, which is divided into three units: isbjørnhamna, eimfjellet and deilegga groups (birkenmajer 1981, 1991). the latter is non-conformably overlain by the low-grade neoproterozoic sofiebogen group, comprising a succession of conglomerates, limestones and dolomites passing up into fine-grained siliciclastic rocks (bjørnerud 1990; czerny et al. 1993; gee & tebenkov 2004). the sofiebogen group is capped by vendian tillites of the kapp lyell group, and comprises a thick series of diamictites (bjørnerud 1990; dallmann et al. 1990; harland et al. 1993). the cambro–ordovician succession is tectonically emplaced atop the proterozoic complexes (dallmann et al. 1993; mazur et al. 2009). wedel jarlsberg land, located in the southern part of the south-western terranes (fig. 2), consists of two proterozoic basement blocks with contrasting metamorphic histories. the northern block comprises rocks of the metasedimentary deilegga and sofiebogen groups, which are separated by a late proterozoic angular unconformity (torellian unconformity; birkenmajer 1975). the southern block corresponds to a stratified volcano-sedimentary polymetamorphic complex that consists of a metasedimentary sequence known as the isbjørnhamna group and a metavolcanic succession of the eimfjellet group (birkenmajer 1958; czerny et al. 1993). the isbjørnhamna group is composed of garnet–mica schists, paragneisses, calc-silicate rocks and marbles subjected to amphibolite-grade barrovian metamorphism, which was followed by greenschist facies metamorphism (smulikowski 1965; majka et al. 2004). the eimfjellet group consists of quartzites, amphibolites and greenschists, accompanied by minor metarhyolites and muscovite schists. these rocks were subjected to greenschist to lower amphibolite facies (czerny et al. 1993). the contact between the two crustal blocks exposed in the south-western part of wedel jarlsberg land between the hornsund fjord and torellbreen glacier is represented by the ca. 2 km wide vkz. the deformation zone is characterized by a heterogeneous array of structures formed during ductile shear deformation. structural features of the vkz indicate bulk sinistral strike-slip to oblique-slip shear strain formed under greenschist facies conditions. thermochronologic data obtained from the isbjørnhamna and eimfjellet groups indicate a neoproterozoic age of metamorphism. 40ar–39ar step heating of mineral separates yielded a 616 my age for hornblende from the fig. 2 geological sketch map of the southwestern part of wedel jarlsberg land (modified from czerny et al. 1993). neoproterozoic metamorphism in southern svalbard j. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd252 eimfjellet group, and 585–575 my ages for muscovite from the isbjørnhamna group (manecki et al. 1998). manecki et al. (1998) interpreted these ages as representing a previously unrecognized episode of neoproterozoic reheating, probably connected with the opening of the iapetus ocean. corroborating evidence of a neoproterozoic tectonothermal event is provided by a metamorphic monazite age of 643 � 9 my recently obtained from the isbjørnhamna group (majka et al. 2008). this age was interpreted to represent the progressive phase of a regional metamorphic event, as monazite grains enclosed in garnet porphyroblasts yielded the same age as matrix monazite grains. a somewhat younger neoproterozoic age (615 my) was obtained on zircons separated from an anatectic pegmatite, which intrudes the isbjørnhamna group (majka et al. 2007). description of metamorphic units the isbjørnhamna group consists of the skoddefjellet, ariekammen and revdalen formations, representing an originally continuous sedimentary succession (birkenmajer 1975). skoddefjellet formation the skoddefjellet formation is composed of interlayered paragneisses and mica schists. typical prograde mineral assemblages in these rocks are qtz + pl + bt + ms � grt � chl with greater quantities of plagioclase in paragneisses and garnet in mica schists. the mica schists are well foliated with common garnet and biotite porphyroblasts. the matrix is mainly composed of quartz, plagioclase (<15% vol.) and phyllosilicates. biotite occurs mainly within the foliation planes, in the pressure shadows of garnet and as a product of garnet decomposition. additionally, biotite forms porphyroblasts transverse to the foliation and enriched in small graphite inclusions. very rarely biotite occurs as inclusions in garnet. muscovite occurs mainly in foliation planes, in the pressure shadows of garnet and sometimes replacing garnet porphyroblasts. primary chlorite occurs in the foliation planes, whereas secondary chlorite replaces micas in the pressure shadows of garnet and occurs as rosettes within the matrix. the accessory phases comprise tourmaline, apatite, zircon, monazite, epidote group minerals, titanite, ilmenite, hematite, pyrite, pyrotite and chalcopyrite. ariekammen formation the ariekammen formation is characterized by the occurrence of carbonate rocks. the formation mostly consists of carbonate–mica schists, with irregular bands of mica schists, paragneisses of the skoddefjellet type and minor marble intercalations. a mineral assemblage characteristic of carbonate-mica schists comprises cal + qtz + bt + grt + pl + ms � ep, with ca-enriched plagioclase and accessory minerals similar to those found in the skoddefjellet formation. additionally, some schist varieties contain rare mejonite. notably, a thin discontinuous horizon of yellow and white marble occurs in the middle of the formation. porphyroblasts of garnet up to 6 cm in diameter are abundant at the base of this horizon. revdalen formation the revdalen formation represents a uniform sequence of rusty weathered mica schist composed of qtz + pl + ms � bt � grt � st � ky � cld � chl. metamorphic isograds within these rocks are defined by the local presence of chloritoid, staurolite or kyanite. the mica schists are well foliated with numerous garnet porphyroblasts and rare transversal biotite and staurolite porphyroblasts. the matrix mostly consists of quartz and phyllosilicates and minor plagioclase. muscovite occurs in all varieties of the revdalen mica schists, whereas biotite is absent from chloritoid-bearing samples, which tend to be rich in primary chlorite. all phyllosilicate types can be found in the pressure shadows of garnet and staurolite, and both micas exist as inclusions in garnet. rare kyanite occurs in samples containing garnet and/or staurolite. the remaining accessory phases comprise abundant tourmaline, zircon, monazite, apatite, epidote (sometimes allanite), titanite, rutile, and fe-oxides and -sulphides. additionally, some younger fe-oxyhydroxides and carbonates are also present. description of textures the isbjørnhamna metapelites exhibit a penetrative planar s1 foliation, a well-developed l1 mineral stretching lineation, particularly in the skoddefjellet mica schists, and locally developed s–c fabrics (most common in the revdalen formation). the s1 foliation is expressed by aligned phyllosilicates and flattened garnet and staurolite porphyroblasts (fig. 3). deformation resulted in the ductile flattening of garnets and the development of asymmetric pressure shadows filled with biotite, muscovite, quartz and plagioclase. the flattened and slightly rotated garnets often contain helicitic inclusions. inclusion trails in rare euhedral garnet porphyroblasts, occurring in low strain zones, parallel the s1 foliation. some staurolite porphyroblasts are slightly flattened and accompanied by pressure shadows filled with muscovite and quartz. in many cases, however, staurolite grains are neoproterozoic metamorphism in southern svalbardj. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 253 inclusion-free and euhedral, with only narrow asymmetric mica-filled pressure shadows. the transversal character of biotite porphyroblasts is expressed by the orientation of their cleavage planes that are oblique to the s1 foliation. the cleavage is underlined by common graphitic encrustations, possibly representing a relict s0 layering. the biotite porphyroblasts are flattened and accompanied by asymmetric tails of finegrained biotite. m1 metamorphism metamorphic isograds are well-defined within the metapelites of the revdalen formation. for samples collected in the north-western part of the study area, from the western limb of a north–south trending anticline outcropping in the rålstranda, the prograde m1 mineral assemblage is defined by grt + cld + ms + chl + qtz � pl. chloritoid-bearing and biotite-absent metapelites occur exclusively in the region of the russepynten cape. eastwards from that region, the mineral assemblage changes into grt + bt + ms + qtz � pl � chl and farther east into grt + st + ms + bt + qtz � pl � chl. by contrast, in the east and south-eastern part of the study area (revdalen, skålfjelldalen and fugleberget), the mineral paragenesis is defined by the occurrence of grt + ms + bt + qtz � pl, whereas only in a very few cases are additional kyanite or kyanite and staurolite recorded. the rare occurrence of al-saturated phases is related to local changes in bulk rock composition. in the schists from the rålstranda area, very fine-grained progressive allanite and epidote were observed, whereas farther east and south the dominant rare earth element-bearing phase is monazite. the transition of allanite into monazite is consistent with the increasing metamorphic grade within the revdalen formation to the east because allanite is stable only at upper greenschist to lower amphibolite facies conditions; with increasing temperatures, allanite is fig. 3 photomicrographs of (a) slightly rotated anhedral garnet with asymmetrically developed pressures shadows and its relationship to biotite; (b) deformed and slightly rotated staurolite; (c) deformed large biotite; and (d) retrogressive rosette-shaped chlorite. neoproterozoic metamorphism in southern svalbard j. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd254 replaced by monazite (e.g., ferry 2000; janots et al. 2007). retrogressive stage of m1 metamorphism a retrogressive alteration was associated with cooling after the peak of m1 metamorphism. in many cases, retrogression resulted in the partial or complete replacement of garnet by the assemblage of bt + ms + pl + q � chl or pl + q � chl. partial replacement of biotite by chlorite may also be related to this phase of metamorphic evolution. additionally, the partial or even complete replacement of monazite by apatite–allanite–epidote coronas in some samples is a common reaction indicative of late-metamorphic cooling (e.g., ferry 2000; majka & budzyń 2006, janots et al. 2007, broska & majka 2008). the character of the retrogressive changes and the mineral assemblage synchronously formed suggest that retrogression took place shortly after the peak of m1 metamorphism. weak caledonian m2 overprint the isbjørnhamna group belongs to proterozoic basement exposed in the core of the west spitsbergen foldand-thrust belt. the main caledonian structure in the study area is the vkz trending from north-west to southeast (czerny et al. 1993; mazur et al. 2009). the effects of caledonian deformation are widespread to the north of this zone. contrastingly, southwards from the vkz, caledonian overprint rapidly dies out in the rigid amphibolite facies tectonic block, including the isbjørnhamna group. only the rocks of the eimfjellet group, which are adjacent to the vkz, experienced intense caledonian mylonitization (mazur et al. 2009), whereas the rocks of the isbjørnhamna group do not reveal any significant caledonian reworking, except in a few relatively thin zones of altered rocks, usually parallel with vkz. the only visible effect of the caledonian event is the partial or sometimes complete chloritization of garnet, biotite and staurolite, as well as the alteration of muscovite porphyroblasts to sericite. additionally, in some cases caledonian alterations are expressed by the development of sericite reaction rims on kyanite, and by sericitization of staurolite and plagioclase. these changes probably took place under static conditions, as indicated by the common growth of rosette-like chlorite neoblasts (fig. 3). mineral chemistry selected minerals were chemically analysed using wavelength dispersive spectrometry with the 100sx electron microprobe (cameca, grennevilliers cedex, france) at the inter-institute analytical complex for minerals and synthetic substances, university of warsaw. the operating conditions were set at 15 kv, 20 na and 20 s of the counting time using natural and synthetic standards. the data were calculated using atomic number, absorption and fluorescence (zaf) corrections. garnets garnets were analysed along rim-core-rim profiles. porphyroblasts of garnet were selected from different metamorphic zones within the revdalen and the skoddefjellet formations. representative traverses are shown in fig. 4. a common feature of garnets from the kyanitefree mica schists (i.e., samples 206, 214 and 125) is the systematic increase of pyrope content from the core to rims, and the contemporary decrease of fe/(fe + mg) and spessartine content. the rimward decrease of fe/(fe + mg) is characteristic of the increase of temperature under upper greenschist and amphibolite facies conditions (spear 1993). the bell-shaped spessartine profile also suggests prograde growth zoning during a one-stage chemical reaction (tracy 1982). the slight increase of spessartine content that was observed in some garnet rims may be related to the consumption of garnet. notably, garnet from the staurolite-bearing mica schists reveals a decrease of fe/(fe + mg) towards the rims, but in the rims this tendency changes and fe/(fe + mg) is flat or even slightly increased. the almandine content in this garnet systematically increases towards the rims, but in the rims it decreases. the opposite trend is evident for the grossular content, which systematically decreases towards the rims, but rapidly increases in the rims. the variation of grossular and almandine content in garnets co-existing with staurolite may have been caused by the onset of staurolite crystallization (see also janák et al. 2001): the onset of staurolite crystallization could modify local chemical equilibrium during garnet crystallization, decreasing the almandine content in garnet, as observed in our samples. contemporaneously, the observed enrichment in ca is probably caused by the reduction of crystallization of plagioclase in response to the appearance of a new al-saturated phase (e.g., staurolite). nevertheless, the smooth shape of decreasing spessartine content suggests prograde growth during a single metamorphic event. the compositional variation in garnet from the kyanite-bearing mica schist (i.e., sample 124) is complex. in all cases the profiles are strongly disturbed, probably as a result of the presence of numerous tiny inclusions and the diffusion that occurred between them and the hosting garnet. nevertheless, the almandine and pyrope zoning neoproterozoic metamorphism in southern svalbardj. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 255 suggest garnet growth during prograde metamorphism, although the distribution of spessartine and grossular content seem to be homogenized. if so, this homogenization may have occurred during an early stage of retrogression (spear 1993), connected with a general decrease of pressure. garnets from the high-al revdalen formation schists (i.e., samples 124 and 206) are characterized by relatively lower grossular and higher almandine content, compared with low-al revdalen formation and skoddefjellet formation schists (samples 125 and 214, respectively). staurolite staurolite porphyroblasts as well as staurolite enclosed in garnets do not reveal any chemical zonation. they are fe-staurolites, with fe in the range of 1.55–1.74 atoms per formula unit (apfu) and mg in the range of fig. 4 examples of typical profiles through garnets from samples 124 (high-al mica schist of revdalen formation, zone 4, diameter = 1.7 mm), 125 (low-al mica schist of the revdalen formation; diameter = 1.5 mm), 206 (high-al mica schist of the revdalen formation, zone 2, diameter = 1.3 mm), 214 (low al mica schist of the skoddefjellet formation, diameter = 1 mm), showing the differences in garnet zoning between high-al revdalen formation, low-al revdalen formation and low-al skoddefjellet formation mica schists, as well as within zones 2 and 4 in the revdalen formation. neoproterozoic metamorphism in southern svalbard j. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd256 0.21–0.29 apfu. the fe/(fe + mg) ratio is in the range 0.85–0.88 (table 1). biotite biotite contains vial in the range of 0.653–0.86 apfu and fe/(fe + mg) in the range of 0.57–0.697 (table 2). ti content in the biotites scatters in the range of 0.085– 0.295 apfu, which is characteristic for biotites from mesozonal rocks of barrovian facies series (henry et al. 2005). only biotites occurring in foliation planes in the vicinity of garnets were used for further geothermobarometric calculations, except sample 124, where we used matrix biotite not in contact with garnet. plagioclase plagioclase crystals differ from each other, depending on their position in the fabric of the mica schists. plagioclase grains in contact with garnet or partially replacing it have an anorthite content in the range of 0.1–0.17. plagioclase grains from the matrix are characterized by a relatively lower level of anorthite molecules of 0.09–0.12 (table 1). these porphyroblasts probably crystallized near the maximum pressure conditions during the d1 deformation. plagioclase grains characterized by the higher level of anorthite molecules presumably formed early during the first stage of decompression, after the pressure associated with the peak of metamorphism, but still under increasing temperature. the lower an plagioclases, located in the matrix, were used for further geobarometrical calculations. pressure–temperature estimates metamorphic zones the petrography and mineral chemistry of the isbjørnhamna group described above point to regional amphibolite facies metamorphism. the observed mineral parageneses in the metapelites are grouped into four metamorphic zones: zone 1, with cld + chl + grt paragenesis in high-al mica schists, and chl + bt + grt paragenesis in low-al mica schists; zone 2, with fig. 5 sample locations with the temperatures obtained and boundaries of mineral zones within the isbjørnhamna group. neoproterozoic metamorphism in southern svalbardj. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 257 table 1 chemical composition of plagioclases used for garnet–al silicate–plagioclase (gasp) geobarometry (with obtained pressures) and chemical composition of staurolites from the isbjørnhamna group metapelites. pl sample st sample 124-1 124-2 124-3 218-1 218a-2 204-core 204-rim 206-core 206-rim sio2 64.853 66.114 65.742 64.918 65.944 sio2 27.815 27.827 27.544 27.473 al2o3 22.478 21.669 21.677 21.950 21.393 tio2 0.428 0.596 0.509 0.638 cao 3.114 2.095 2.306 3.325 2.513 al2o3 53.190 54.364 53.379 53.274 feo 0.098 0.074 0.059 0.456 0.031 mgo 1.391 1.208 1.112 0.988 bao 0.000 0.000 0.072 na na cao 0.006 0.024 0.000 0.000 na2o 10.167 10.422 10.181 9.735 10.198 mno 0.070 0.038 0.037 0.030 k2o 0.022 0.000 0.031 0.039 0.007 feo 14.839 13.934 13.478 13.227 total 100.733 100.374 100.068 100.423 100.086 zno 0.034 0.033 0.202 0.286 h2o 2.149 2.167 2.129 2.123 si 2.839 2.891 2.886 2.853 2.894 total 99.922 100.191 98.390 98.039 al 1.160 1.117 1.122 1.137 1.106 ca 0.146 0.098 0.108 0.157 0.118 si 3.880 3.851 3.879 3.880 fe 0.004 0.003 0.002 0.017 0.001 ti 0.045 0.062 0.054 0.068 ba 0.000 0.000 0.001 na na al 8.745 8.867 8.859 8.867 na 0.863 0.884 0.867 0.829 0.868 mg 0.289 0.249 0.233 0.208 k 0.001 0.000 0.002 0.002 0.000 ca 0.001 0.004 0.000 0.000 total 5.013 4.992 4.988 4.995 4.987 mn 0.008 0.005 0.004 0.004 fe 1.731 1.613 1.587 1.562 ab 85.420 90.000 88.610 83.907 88.032 zn 0.004 0.003 0.021 0.030 an 14.460 10.000 11.090 15.891 11.968 total 14.703 14.654 14.637 14.619 or 0.120 0.000 0.180 0.202 0.000 cs 0.120 0.000 0.180 — — fe/(fe+mg) 0.857 0.866 0.872 0.882 p(kbar) 9.84 11.22 11.29 6.60 8.77 derived 2s errors of ca. 0.8 kbar for geobarometry (holdaway 2000, 2001) have been used. table 2 chemical composition of garnets and biotites used for geothermometry and obtained temperatures. sample grt bt py alm grs sps fe/(fe + mg) fe/(fe + mg) ti temp. 103 9.685 77.446 11.045 1.824 0.889 0.578 0.235 604 104 8.337 79.280 11.623 0.759 0.905 0.579 0.190 574 106 4.887 67.799 19.082 8.233 0.933 0.613 0.194 542 111 9.490 75.572 11.779 3.158 0.888 0.614 0.085 675 119 9.312 74.120 14.692 1.876 0.888 0.640 0.182 668 123 8.521 76.359 11.180 3.940 0.900 0.634 0.231 631 124 8.830 81.673 6.581 2.916 0.902 0.594 0.222 655 125 6.010 71.476 19.426 3.088 0.922 0.655 0.282 597 126 7.536 70.953 16.620 4.891 0.904 0.618 0.143 616 203 6.679 66.571 22.196 4.554 0.909 0.517 0.173 553 204 8.033 84.134 5.774 2.059 0.913 0.583 0.158 580 206 7.402 89.433 1.945 1.220 0.924 0.576 0.203 519 208 8.672 67.678 20.397 3.252 0.886 0.627 0.169 671 211 6.166 71.925 17.383 4.526 0.921 0.657 0.178 648 214 10.195 74.263 13.343 2.199 0.879 0.623 0.232 667 216 10.090 80.443 6.284 3.183 0.889 0.572 0.192 596 217 10.376 82.923 3.292 3.409 0.889 0.627 0.209 642 218 13.610 80.204 4.727 1.458 0.855 0.582 0.185 624 219 8.218 71.436 20.230 0.116 0.897 0.572 0.137 634 220 7.867 72.259 9.391 10.484 0.902 0.637 0.234 633 221 6.559 76.095 16.880 0.466 0.921 0.626 0.148 574 222 8.337 79.280 11.623 0.759 0.905 0.579 0.190 661 derived 2s errors of ca. 25°c for geothermometry (holdaway 2000, 2001) have been used. neoproterozoic metamorphism in southern svalbard j. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd258 chl + grt + st � bt paragenesis in high-al mica schists, and grt + chl + bt paragenesis in low-al mica schists; zone 3, with grt + st + bt + ky � chl assemblage in high-al mica schists and grt + bt + st � chl in low-al mica schists; zone 4, with grt + ky + bt in high-al mica schists and grt + bt in low-al mica schists. metamorphic isograds are defined on the first occurrence of the afm mineral. the boundary between zones 1 and 2 was delineated by the first appearance of staurolite. the mineral assemblage for zone 2 was recognized only in one sample of high-al mica schists, and thus the boundary between zones 1 and 2 is speculative. the boundary between zones 2 and 3 is defined by the broad appearance of biotite and staurolite and between zones 3 and 4 by the disappearance of staurolite. the observed parageneses and metamorphic zones suggest a sequence of index mineral reactions characteristic of continuously increasing pressure–temperature (p–t) conditions from upper greenschist to middle/upper amphibolite facies conditions at moderate to high pressure. metamorphic zoning without a chloritoid + biotite assemblage is well recognized in several kyanite-bearing metamorphic complexes (e.g., spear 1993; bucher and frey 1994). geothermobarometry we used the garnet–al silicate–plagioclase (gasp) geobarometer (holdaway 2001) to quantitatively estimate the peak pressure conditions. the pressure was calculated only in samples containing an al2sio5 polymorph (kyanite in this case). only five plagioclase–garnet pairs were analysed in both samples, mainly because of strong retrogressive changes. those analysed, however, were not affected by strong retrogression. the results obtained are in the range of 9.84–11.3 kbar for sample 124, and 6.6–8.77 kbar for sample 218 (see table 2 and fig. 5 for the location of samples), and are relatively consistent with pargeneses observed in the investigated samples. for peak temperature estimation, the garnet–biotite geothermometer (holdaway et al. 1997; holdaway 2000) was used. the temperatures were calculated for a normative pressure of 9 kbar on the basis of mineral paragenesis and previous preliminary pressure estimates (majka 2003; majka et al. 2004). the lowest fe/(fe + mg) values (usually rim) were used for further geothermometrical calculations. the calculated temperatures are scattered in the range of 530–675°c (fig. 5; table 2). the general tendency observed in the isbjørnhamna group is that calculated temperatures increase from 519 to 604°c in the rålstranada area (samples 103, 104, 106 and 203), and from 624 to 675°c in the upper revdalen area (samples 119, 123, 124, 208, 217 and 218), which appears in the core of the ariebreen anticline (samples 111, 211 and 214). slightly lower temperatures (596– 634°c) were recorded for the samples collected from the south and south-east limb of the ariebreen anticline (samples 216, 219 and 220). similarly, for the samples from the fuglebereget–vesletuva area (samples 125, 126, 221 and 222), temperatures in the range of 574–628°c were obtained. comparison of geothermobarometrical results and kfmash petrogenetic grid the k2o–feo–mgo–al2o3–sio2–h2o (kfmash) petrogenetic grid (spear & cheney 1989) was used to better constrain the p–t path based on our geothermobarometric results. only the samples from the revdalen formation, showing well-developed metamorphic zonation, were used. observed mineral prageneses of high-al mica schists can be represented by the kfmash system. the fe/(fe + mg) ratios in analysed minerals decreases in the order garnet > staurolite > biotite, similar to many metapelites from all over the world (e.g., thompson 1976; spear 1993). therefore, we decided to ignore the minor components mno, na2o, tio2 and cao while choosing the petrogenetic grid. the paragenetic mineral assemblage in samples with the lowest metamorphic grade in the revdalen formation, which crop out in the russepynten cape area, indicates that these rocks were metamorphosed above the chloritoid and garnet isograds. the lack of biotite in this mica schist variety does not mean that these rocks were formed below the biotite isograd. in accordance with the kfmash system, the co-existence of chloritoid, chlorite and garnet in the paragenesis means that chloritoid-bearing mica schists could have been formed in the temperature range of 450–520°c. only above the temperature of ca. 520°c is chlorite replaced by the garnet–biotite assemblage. similarly, chloritoid can be unstable, but in very specific cases it is stable up to 550°c (bucher & frey 1994). more eastwards but still in the rålstranda and torbjørnsenfjellelt areas the index mineral assemblage changes into grt + bt + chl, grt + st � bt � chl and grt + bt + st � chl. such a change means an increase in temperature above 520°c for samples without staurolite, and a further increase in temperature above 550°c in rocks containing staurolite. the stability of the latter paragenesis is restricted much more by pressure than by temperature. generally, the maximum temperature of staurolite stability decreases with an increase in pressure. the obtained temperature of 580°c for sample 204 probably corresponds to a pressure of 8–9 kbar. further east in the upper revdalen valley region, staurolite disappears from the paragenesis, and is replaced by kyanite. this paragenetic mineral assemblage is stable neoproterozoic metamorphism in southern svalbardj. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 259 above a temperature of 630°c at 11 kbar. the results from geothermobarometry are consistent (sample 124) at ca. 646°c and a maximum pressure of ca. 11 kbar. additionally, the probable homogenization of garnet from this sample suggests that the rock was metamorphosed under relatively high-grade conditions. rocks from the north-eastern part of the study area contain both kyanite and staurolite. this mineral assemblage is stable in a relatively small p–t field at temperatures of ca. 640–680°c and pressures of ca. 9–10 kbar. the geothermobarometrical results for this variety of the revdalen mica schists yielded a temperature of ca. 628°c and pressures of 6.6–8.77 kbar. the 628°c temperature is fairly consistent with the stability field of the grt + bt + st + ky paragenesis, and the pressure is within error of the expected pressure field. in the remaining two samples (217 and 125), no al-saturated phases were observed, as expected for the low bulk al content in these rocks. nevertheless, the temperatures of 636°c for sample 217 and 597°c for sample 125 are reasonable. sample 217 was collected not far away from samples 218 and 124, and a similar temperature estimation therefore seems likely. sample 125 comes from the area at the south-eastern extremity of the revdalen formation, and the temperature obtained is comparable with that calculated for sample 126 (fig. 5). as the transformation of kyanite into sillimanite or andalusite is not documented in the studied rocks, cooling possibly took place within the kyanite stability field. accordingly, the retrograde part of the p–t path obtained for the revdalen mica schists does not cross the boundaries of sillimanite and andalusite stability fields (fig. 6). cooling rate using previous geochronological data (manecki et al. 1998; majka et al. 2008) and thermometrical results presented in this paper, it is possible to reconstruct the cooling history of the isbjørnhamna group. manecki et al. (1998) reported 585–575 my 40ar–39ar cooling ages for muscovite from the isbjørnhamna group and a 616 my 40ar–39ar cooling age for hornblende from the overlying eimfjellet group. the closing temperatures for muscovite and hornblende are ca. 350°c and ca. 550°c, respectively. majka et al. (2008) obtained a 643 my u–th–total pb age for monazites located both in the matrix of mica schists and enclosed in garnet porphyrofig. 6 k2o–feo–mgo–al2o3–sio2–h2o (kfmash) petrogenetic grid (modified from spear & cheney 1989; spear & cheney unpubl. data) with the pressure–temperature (p–t) path marked for the isbjørnhamna group rocks. neoproterozoic metamorphism in southern svalbard j. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd260 blasts, constraining the growth of garnet in the isbjørnhamna group at 643 mya. from the data mentioned above and with three points on the age– temperature diagram, we construct a nominal cooling path for the neoproterozoic metamorphic volcanic terrane (fig. 7). the generally smooth shape of the cooling path suggests a cooling rate of ca. 5°c my-1. such a cooling rate corresponds well with those reported from the neoproterozoic pan-african orogens (e.g., möller et al. 2000). on average, cooling rates increase through geological time, and are an order of magnitude faster in phanerozoic than in precambrian settings (dunlap 2000). despite the unavoidable simplifications, the compilation of temperature–time (t–t) paths by willigers et al. (2002) shows that a cooling rate around 5°c my-1 is typical of neoproterozoic orogens. two possible forms of the t–t path for the isbjørnhamna group are proposed (fig. 7). one assumes a moderate reheating at ca. 480 mya, the approximate time of metamorphism in the northern tectonic block of wedel jarlberg land (mazur et al. 2009). the other postulates a decrease of the cooling rate from 575 mya onwards. further thermochronological studies are necessary to differentiate between these two possibilities. concluding remarks the revdalen formation is a <200 m thick continuous horizon that provides an excellent marker for investigating lateral changes in p–t metamorphic conditions. on the basis of the metamorphic mineral zonation and p–t estimates, an increase of p–t conditions from west (rålstranda area) to east (revdalen valley area) is observed. only the slight south-eastward temperature decrease in the fugleberget area departs from this general trend. taking into account the thermometric results from the skoddefjellet mica schists, a similar trend in temperature change can be extrapolated for the entire isbjørnhamna group. maximum temperatures were obtained from the core of the ariebreen anticline, whereas the calculated temperatures continuously decrease toward the limbs of this antiform and the western part of the study area. this relationship indicates that large-scale folding of the isbjørnhamna group occurred after the peak of metamorphism. because the folds are crosscut by the vkz, displacement along this shear zone must have been even later. indeed, the isograds defined for the revdalen formation are oblique to the trend of the vkz. in summary, the peak temperature and pressure conditions of neoproterozoic metamorphism are estimated at ca. 670°c and �11 kbar. the geothermobarometric results are consistent with previous preliminary estimates of the p–t rockforming conditions (smulikowski 1965; czerny et al. 1993; majka et al. 2004). the microstructural observations show that the pervasive fabric of the isbjørnhamna rocks formed under conditions close to the peak of metamorphism. as the constructed isograds are oblique to the foliation and lithological contacts, the penetrative deformation must have slightly preceded the peak temperature. the latter was followed by the folding of already developed foliation before the initiation of the vkz. considering that the vkz was developed in the early ordovician (mazur et al. 2009), the structural grain of the isbjørnhamna group and the entire southern tectonic block of wedel jarlsberg land must have been formed in neoproterozoic to cambrian times. the t–t path of the isbjørnhamna group shows cooling at a rate of ca. 5°c my-1, interpreted to be related to slow erosion controlled exhumation, rather than rapid uplift connected to tectonic activity. notably, cooling continued undisturbed at least until the early ordovician, the time of postulated juxtaposition of the neoproterozoic complex against the northern part of svalbard’s southwestern terrane. our data confirm that the southern tectonic block of wedel jarlsberg land represents a fragment of a neoproterozoic orogen, with a well-preserved structural grain and metamorphic zonation. this neoproterozoic domain seems to be entirely exotic compared with svalbard’s remaining terranes, and is only weakly overprinted by caledonian metamorphism. the neoproterozoic terrane could not have been derived from the north american margin, as postulated for the rest of svalbard’s crustal fig. 7 hypothetical cooling paths for the isbjørnhamna group, based on data published by manecki et al. (1998), majka et al. (2008) and this paper. path 1 assumes moderate reheating at ca. 480 mya, whereas path 2 postulates a decrease in the cooling rate from 575 mya onwards. neoproterozoic metamorphism in southern svalbardj. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 261 fragments (gee & tebenkov 2004). instead, its presence is more in line with models suggesting large-scale strike-slip displacements during the early palaeozoic assembly of the svalbard archipelago (e.g., harland & gayer 1972; harland 1985; gee & page 1994). the most straightforward explanation for the origin of the neoproterozoic terrane is a derivation from the timanide belt of northeastern europe. however, such a correlation has two important implications that require further verification and discussion. firstly, the neoproterozoic orogeny must have commenced at least before the opening of the iapetus ocean, as the svalbard archipelago is separated from europe by caledonian sutures (gee & tebenkov 2004). secondly, the linkage between southwestern svalbard and the timanide belt cannot be reconciled with the large-scale early palaeozoic rotation of baltica that has been postulated by hartz & torsvik (2002). ongoing studies characterizing the metamorphic, structural and magmatic histories of neoproterozoic circum-arctic terranes are necessary in order to better constrain neoproterozoic paleogeographic reconstructions and the proposed younger tectonic evolution models for the region (amato et al. 2009). acknowledgements this research was supported by mniszw grant no. 2p04d03930. jm was also supported by the swedish institute, visby programme and ymer-80 foundation. we are grateful to two anonymous reviewers for their constructive comments improving the manuscript, and to l. jeżak and p. dzierżanowski (warsaw university) for their assistance with the electron microprobe analyses. references amato j.m., toro j., miller e., gehrels g.e., farmer l., gottlieb e. & till a.b. 2009. late proterozoic–paleozoic evolution of the arctic alaska–chukotka terrane based on u–pb igneous and detrital zircon ages: implications for neoproterozoic paleogeographic reconstructions. geological society of america bulletin 121, 1219–1235. armstrong h.a., nakrem h.a. & ohta y. 1986. ordovician conodonts from the bulltinden formation, motalafjella, central-western spitsbergen. polar research 4, 17–23. balashov j.a., tebenkov a.m., ohta y., larionov a.n., sirostkin a.n., gannibal l.f. & ryungenen g.i. 1995. grenvillian u–pb zircon ages of quartz porphyry and rhyolite clasts in a metacoglomerate at vimsodden, southern spitsbergen. polar research 14, 291–302. bergh s.g., braathen a. & andresen a. 1997. interaction of basement-involved and thin-skinned tectonism in the tertiary fold–thrust belt of central spitsbergen, svalbard. aapg bulletin 81, 637–661. birkenmajer k. 1958. preliminary report on the stratigraphy of the hecla hoek formation in wedel jarlsberg land, vestspitsbergen. bulletin de l’academie polonaise des sciences, serie des sciences chimiques, geologiques et geographiques 6, 143–150. birkenmajer k. 1975. caledonides of svalbard and plate tectonics. bulletin of the geological society of denmark 24, 1–19. birkenmajer k. 1981. the geology of svalbard, the western part of the barents sea, and the continental margin of scandinavia. in a.e.m. nairn et al. (eds.): the arctic ocean. the ocean basins and margins. part 5. pp. 265–329. new york: plenum. birkenmajer k. 1991. the jarlsbergian unconformity (proterozoic/cambrian boundary) and the problem of varangian tillites in south spitsbergen. polish polar research 12, 269–278. bjørnerud m. 1990. upper proterozoic unconformity in northern wedel-jarlsberg land, southwest spitsbergen: lithostratigrapby and tectonic implications. polar research 8, 127–140. braathen a., bergh s.g. & maher h.d. 1995. structural outline of a tertiary basement-cored uplift/inversion structure in western spitsbergen, svalbard: kinematics and controlling factors. tectonics 14, 95–119. broska i. & majka j. 2008. transformation of phosphates to silicates: from metasomatism to hydrothermal breakdown? in d. harlov & i. broska (eds.): mineral equilibria, metasomatism and mass transport: evolution and stabilisation of rock on a fluid-rich world. proceedings from mimet 2008 workshop smolenice, slovak republic, april 8–10. pp. 18–21. bratislava: geological institute, slovak academy of sciences. bucher k. & frey m. 1994. petrogenesis of metamorphic rocks. berlin: springer. czerny j., kieres a., manecki m. & rajchel j. 1993. geological map of the sw part of wedel jarlsberg land, spitsbergen 1:25 000. kraków: institute of geology and mineral deposits. czerny j., majka j., gee d.g., manecki a. & manecki m. 2010. torellian oregony: evidence of a late proterozoic tectonometamorphic event in southwestern svalbard’s caledonian basement. in h.a. nakrem et al. (eds.): 29th nordic geological winter meeting. abstracts and proceedings of the geological society of norway 1 2010. pp. 35–36. trondheim: geological society of norway. dallmann w.k., andresen a., bergh s.g., maher h.d. & ohta y. 1993. tertiary fold-and-thrust belt of spitsbergen (svalbard). norsk polarinstitutt meddelelser 128. oslo: norwegian polar institute. dallmann w.k., hjelle a., ohta y., salvigsen o., maher h.d., bjørnerud m., hauser e.c. & craddock c. 1990. geological map of svalbard 1:100 000, b11g van keulenfjorden. norsk polarinstitutt temakart 15. oslo: norwegian polar institute. dallmeyer r.d., peucat j.j. & ohta y. 1990. tectonothermal evolution of contrasting metamorphic complexes in northwestern spitsbergen (biskayerhalvøya): evidence neoproterozoic metamorphism in southern svalbard j. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd262 from 40ar/39ar and rb-sr mineral ages. geological society of america bulletin 102, 653–663. dunlap w.j. 2000. nature’s diffusion experiment: the cooling-rate cooling-age correlation. geology 28, 139–142. ferry j.m. 2000. patterns of mineral occurrence in metamorphic rocks. american mineralogist 85, 1573–1588. gee d.g. 1986. svalbard’s caledonian terranes reviewed. geologiska föreningens stockholm förhandlingar 108, 284–286. gee d.g., johansson å., ohta y., tebenkov a.m., krasil’ščhikov a.a., balashov y.a., larionov a.n., gannibal l.f. & ryungenen g.i. 1995. grenvillian basement and a major unconformity within the caledonides of nordaustlandet, svalbard. precambrian research 70, 215–234. gee d.g. & page l.m. 1994. caledonian terrane assembly on svalbard: new evidence from 40ar/39ar dating in ny friesland. american journal of science 294, 1166–1186. gee d.g. & tebenkov a.m. 2004. svalbard: a fragment of the laurentian margin. in d.g. gee & v. pease (eds.): the neoproterozoic timanide orogen of eastern baltica. geological society memoir 30. pp. 191–206. bath: geological society. harland w.b. 1972. early palaeozoic faults as margins of arctic plates in svalbard. in j. gill (ed.): international geological congress. twenty-fourth session. section 3. tectonics. pp. 230–237. montreal: international geological congress. harland w.b. 1985. caledonide svalbard. in gee d.g. & sturt b.a. (eds.): the caledonide orogen—scandinavia and related areas. pp. 999–1016. chichester: wiley. harland w.b. & gayer r.a. 1972. the arctic caledonides and earlier oceans. geological magazine 109, 289–314. harland w.b., hambry m.j. & waddams p. 1993. the vendian geology of svalbard. norsk polarinstitutt skrifter 193. oslo: norwegian polar institute. harland w.b., scott r.a., auckland k.a. & snape l. 1992. the ny friesland orogen, spitsbergen. geological magazine 129, 679–708. hartz e.h. & torsvik t.h. 2002. baltica upside-down: a new plate-tectonic model for rodinia and the iapetus ocean. geology 30, 255–258. hellman f.j., gee d.g., johansson å. & witt-nilsson p. 1997. single-zircon pb evaporation geochronology constrains basement-cover relationships in the lower hecla hoek complex of northern ny friesland, svalbard. chemical geology 137, 117–134. henry d.j., guidotti c.v. & thomson j.a. 2005. the ti-saturation surface for low-to-medium pressure metapelitic biotites: implications for geothermometry and ti-substitution mechanisms. american mineralogist 90, 316–328. holdaway m.j. 2000. application of new experimental and garnet margules data to the garnet–biotite geothermometer. american mineralogist 85, 881–892. holdaway m.j. 2001. recalibration of the gasp geobarometer in light of recent garnet and plagioclase activity models and versions of the garnet–biotite geothermometer. american mineralogist 86, 1117–1129. holdaway m.j., mukhopadhyay b., dyar m.d., guidotti c.v. & durow b.l. 1997. american mineralogist 82, 582–595. holtedahl o. 1926. notes on the geology of northwestern spitsbergen. skrifter om svalbard og ishavet 8. oslo: norwegian polar institute. janák m., plašienka d., frey m., cosca m., schmidt s.t., lupták b. & méres s. 2001. cretaceous evolution of a metamorphic core complex, the veporic unit, western carpathians (slovakia): p–t conditions and in situ 40ar/ 39ar uv laser probe dating of metapelites. journal of metamorphic geology 19, 197–216. janots e. , brunet f., goffé b., poinssot c., burchard m. & cemič l. 2007. thermochemistry of monazite-(la) and dissakisite-(la): implications for monazite and allanite stability in metapelites. contributions to mineralogy and petrology 154, 1–14. johansson å., larionov a.n., gee d.g., ohta y., tebenkov a.m. & sandelin s. 2004. grenvillian and caledonian tectono-magmatic activity in northeasternmost svalbard. in d.g. gee & v. pease (eds.): the neoproterozoic timanide orogen of eastern baltica. geological society memoir 30. pp. 207–232. bath: geological society. krasil’ščikov a.a. 1979. stratigraphy and tectonics of the precambrian of svalbard. in t.s. winsnes (ed.): the geological development of svalbard during the precambrian, lower palaeozoic, and devonian. symposium on svalbard’s geology. oslo, 2–5 june, 1975. norsk polarinstitutt skrifter 167. pp. 73–80. oslo: norwegian polar institute. lowell j.d. 1972. spitsbergen tertiary orogenic belt and the spitsbergen fracture zone. geological society of america bulletin 83, 3091–3102. majka j. 2003. warunki metamorfizmu skał grupy isbjørnhamna (ziemia wedel jarlsberga, spitsbergen) w świetle badań geotermobarometrycznych. (metamorphic conditions of the isbjørnhamna group rocks [wedel jarlsberg land, svalbard] in the light of geothermobarometry.) master’s thesis, agh–university of sciences and technology, kraków. majka j. & budzyń b. 2006. monazite breakdown in metapelites from wedel jarlsberg land, svalbard— preliminary report. mineralogia polonica 37, 61–69. majka j., czerny j. & manecki m. 2004. petrographical characteristics of the isbjørnhamna group rocks (wedel jarlsberg land, spitsbergen). mineralogical society of poland, special papers 24, 279–282. majka j., gee d.g., larionov a., czerny j., wypych a. & manecki m. 2007. neoproterozoic zircon age from anathectic pegmatite, isbjørnhamna group (wedel jarlsberg land, svalbard). icam v. 5th international conference on arctic margins. 3–5 september 2007. tromsø, norway. ngf abstracts and proceedings 2, 2. majka j., mazur s., manecki m. czerny j. & holm d. 2008. late neoproterozoic amphibolite facies metamorphism of a pre-caledonian basement block in southwest wedel jarlsberg land, spitsbergen: new evidence from u–th–pb dating of monazite. geological magazine 145, 822–830. manecki m., holm d.k., czerny j. & lux d. 1998. thermochronological evidence for late proterozoic neoproterozoic metamorphism in southern svalbardj. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 263 (vendian) cooling in southwest wedel jarlsberg land, spitsbergen. geological magazine 135, 63–69. mazur s., czerny j., majka j., manecki m., holm d.k., smyrak a. & wypych a. 2009. a strike–slip terrane boundary in wedel jarlsberg land, svalbard, and its bearing on correlations of sw spitsbergen with the pearya terrane and timanide belt. journal of the geological society 166, 529–544. möller a., mezger k. & schenk v. 2000. u–pb dating of metamorphic minerals: pan-african metamorphism and prolonged slow cooling of high-pressure granulites in tanzania, east africa. precambrian research 104, 123–147. ohta y. 1979. blue schists from motalafjella, western spitsbergen. in t.s. winsnes (ed.): the geological development of svalbard during the precambrian, lower palaeozoic, and devonian. symposium on svalbard’s geology. oslo, 2–5 june 1975. norsk polarinstitutt skrifter 167. pp. 171–217. oslo: norwegian polar institute. ohta y. 1982. lithostratigraphy of the hecla hoek rocks in central nordaustlandet and their relationships to the caledonian granitic–migmatitic rocks. in y. ohta (ed.): hecla hoek rocks in central and western nordaustlandet. norsk polarinstitutt skrifter 178. pp. 41–60. oslo: norwegian polar institute. pettersson c.h., tebenkov a.m., larionov a.n., andresen a. & pease v. 2009. timing of migmatization and granite genesis in the northwestern terrane of svalbard, norway: implications for regional correlations in the arctic caledonides. journal of the geological society 166, 147–158. peucat j.j., ohta y., gee d.g. & bernard-griffiths j. 1989. u–pb, sr, and nd evidence for grenvillian and latest proterozoic tectonothermal activity in the spitsbergen caledonides, arctic ocean. lithos 22, 275–285. sandford k.s. 1956. the stratigraphy and structure of the hecla hoek formation and its relationship to a subjacent metamorphic complex in north-east land (spitsbergen). quarterly journal of the geological society london 112, 339–362. scrutton c.t., horseield w.t. & harland w.b. 1976. silurian fossils from western spitsbergen. geological magazine 113, 519–523. smulikowski w. 1965. petrology and some structural data of lowermetamorphic formations of the hecla hoek succession in hornsund, vestspitsbergen. studia geologica polonica 18. warsaw: institute of geological sciences, polish academy of sciences. spear f.s. 1993. metamorphic phase equilibria and pressure-temperature-time paths. washington d.c.: mineralogical society of america. spear f.s. & cheney j.t. 1989. a petrogenetic grid for pelitic schists in the system sio2-al2o3-feo-mgo-k2o-h2o. contributions to mineralogy and petrology 101, 149–164. thompson a.b. 1976. mineral reactions in pelitic rocks. ii. calculation of some p–t–x(fe–mg) phase relations. american journal of science 276, 425–454. tracy r.j. 1982. compositional zoning and inclusions in metamorphic minerals. reviews in mineralogy 10, 355–394. willigers b.j.a., van gool j.a.m., wijbrans j.r., krogstad e.j. & mezger k. 2002. post-tectonic cooling of the nagssugtoqidian orogen and a comparison of contrasting cooling histories in precambrian and phanerozoic orogens. the journal of geology 110, 503–517. neoproterozoic metamorphism in southern svalbard j. majka et al. polar research 29 2010 250–264 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd264 por_015.fm polar research 26 2007 113 – 117 © 2007 the authors 113 blackwell publishing incmalden, usaporpolar research0800-03952007 blackwell publishing ltd? 2007262113117original article status of black-legged kittiwakes, common guillemots and brünnich’s guillemotsy. v. krasnov et al. status of black-legged kittiwakes ( rissa tridactyla ), common guillemots ( uria aalge ) and brünnich’s guillemots ( u. lomvia ) in murman, north-west russia, and varanger, north-east norway yuri v. krasnov 1 , robert t. barrett 2 & natalie g. nikolaeva 3 1 murmansk marine biological institute, vladimirskaya st. 17, ru 183010 murmansk, russia 2 tromsø university museum, zoology department, no-9037 tromsø, norway 3 russian bird conservation union, entuziastov shosse, 60 bld. 1, ru 111123 moscow, russia abstract recent published estimates of the numbers of seabirds breeding along the coast of murman have been partly based on data collected in the 1960s. counts made in some of the largest colonies in 1999–2005 show that the present populations of black-legged kittiwakes ( rissa tridactyla ), common guillemots ( uria aalge ) and brünnich’s guillemot ( u. lomvia ) in murman are approximately 110 000 pairs, 10 000–12 000 pairs and 2000–3000 pairs, respectively. in varanger the numbers are ca. 32 000 pairs, 6000–7000 pairs and 400–500 pairs, respectively. although there has been a large decline in black-legged kittiwake numbers in the varanger region since 1980, there is no evidence of a similar decline in murman at least until 1999. with the exception of one colony in murman, numbers of common guillemots breeding throughout the region seem to have recovered after suffering a huge decline in 1986/87. keywords kittiwakei; guillemot; population status; barents sea. the barents sea is one of the most important seabird areas in the world, with more than seven million pairs of about 40 species breeding in several hundred colonies on svalbard, frans josef land, novaya zemlya and along the mainland coasts of north-west russia and north-east norway (anker-nilssen et al. 2000). in recent years concern has been raised about the effects that climate change may have on arctic and subarctic species, and emphasis has been put on the need for sound documentation of animal population dynamics. for example, recent studies have demonstrated climatedriven changes at low and mid-trophic levels, and how these have affected seabirds (durant et al. 2003, 2006; frederiksen et al. 2006). furthermore, the huge fluctuations in forage fish stocks (capelin [ mallotus villosus ] and herring [ clupea harengus ]) the development and transport of petroleum resources in the barents sea off the murman and finnmark coast, and the huge impact these can have on seabirds has resulted in the need of new appraisals of the status and population trends of seabirds breeding in the area (quillfeldt & dommasnes 2005a,b; iversen et al. 2006). although extensive documentation was recently published in a status report for the barents sea (anker-nilssen et al. 2000), totals for some of the russian colonies dated as far back as the early 1960s (gerasimova 1962). here we present up-to-date estimates of the populations of three of the common species, the blacklegged kittiwake (hereafter kittiwake [ rissa tridactyla ]), common guillemot ( uria aalge ) and brünnich’s guillemot ( u. lomvia ) on all colonies in the varanger area of east finnmark, and on the five largest colonies on the coast of murman (which contained > 95% of all guillemots and > 80% of all black-legged kittiwakes breeding in the region; golovkin 1984). material and methods of the five largest colonies of kittiwakes and guillemots along the murman coast (fig. 1), two (kharlov and kuvshin) were surveyed in 1995–1999 and three (cape gorodetskiy, cape krutik and dvorovaya bay) were surveyed in one or more years between 2000 and 2005. colonies in sør-varanger, store ekkerøy and hornøya (fig. 1) were surveyed in 2006, and two smaller colonies in the inner part of the varanger fjord were surveyed in 1999. all surveys were made during the incubation and/or hatching periods. in russia, single counts were made correspondence robert t. barrett, tromsø university museum, zoology department, no-9037 tromsø, norway. e-mail: robb@tmu.uit.no doi:10.1111/j.1751-8369.2007.00015.x 114 polar research 26 2007 113 – 117 © 2007 the authors status of black-legged kittiwakes, common guillemots and brünnich’s guillemots y. v. krasnov et al. from the land either directly or, in the densest parts of the colonies, from photographs. in varanger, nearly all kittiwake counts were made directly from the deck of rv johan ruud (110 ft) or, in the case of the largest colonies, from mosaics of digital colour photographs taken from the same platform. at cape gorodetskiy, on the east coast of the ribachiy peninsula, a total count was made in 2000. photographs were taken of the densest parts of the colony, and 13 kittiwake and five guillemot control plots were used as the basis for the next count in 2002. at cape krutik, near dalniye zelentsi, annual counts of kittiwakes and guillemots were made in 2000–2003 and 2004. at dvorovaya bay, counts were made in 2003 and 2005. total counts were made from land in 2003; in 2005 total counts of guillemots were also made from land, whereas numbers of kittiwakes were determined from counts in control plots. at kharlov and kuvshin, population counts were made in 1999 as part of the then ongoing monitoring of the colony (krasnov et al. 1995). kittiwake clutch sizes (numbers of eggs in samples of nests containing eggs) were recorded in each colony at each visit. in norway, all colonies in sør-varanger and at store ekkerøy were visited once on 8–11 june 2006, whereas hornøya has been visited over longer periods almost every year since 1980 for detailed monitoring (barrett 2001; lorentsen 2006). a total count of kittiwakes at hornøya was made in june 2006, based on a combination of direct counts on some of the cliffs and counts from photographs of the remainder. estimates of the total guillemot population at hornøya were based on single total counts made during the late incubation period in 1996 and 2001, and on detailed monitoring counts since 1988 (barrett 2001). counting units were apparently occupied nests for kittiwakes and individuals for guillemots. results kittiwake about 50 000 pairs of kittiwakes were counted at cape gorodetskiy in 2000, making it the largest colony in murman (table 1). based on counts of 4425 nests in 13 plots established in 2000 (and which made up ca. 3% of the total population), the population in 2002 was estimated to be 48 000 pairs. at dvorovaya bay, a total count of 32 330 pairs was made in 2003. based on plots containing 946 nests (or 9% of the population) in 2003 and 1101 nests in 2005, the 2005 total was estimated to be ca. 37 000 pairs, making dvorovaya bay the second largest colony in murman. a further 3500 pairs were counted on cape krutik and, in 1999, 23 000 pairs were counted on kharlov, giving a total of ca. 110 000 pairs in the four colonies. assuming that they constitute 80% of the total population, this gives a figure of ca. 140 000 pairs for murman. around the varanger fjord, about 3500 pairs of kittiwakes were counted in sør-varanger, 15 500 pairs on store ekkerøy and 11 500–12 000 pairs on hornøya in 2006. with a near halving of numbers on hornøya since the early 1980s (lorentsen 2006; barrett et al. in press), the population on the neighbouring island reinøya (2000 pairs in 1983; furness & barrett 1985) was estimated to be ca. 1000 pairs in 2006. a further 900 pairs were counted on two colonies in the inner part of varanger fjord in 1999 (fugleberget, 700 pairs; skjaaholmen, 200 pairs). this gives a total of about 31 000–32 000 pairs breeding between the norwegian–russian border and hornøya. kittiwake clutch sizes are given in table 2. fig. 1 map showing the main seabird colonies in varanger and along the murman coast. (map outline from http://www.aquarius.ifm-geomar.de/ make_map.html.) table 1 numbers of black-legged kittiwake ( rissa tridactyla ) (apparently occupied nests) counted in colonies along the murman coast in 1999– 2005. colony number year cape gorodetskiy 50 175 2000 47 666 a 2002 cape krutik 4 286 2000 3 420 2002 3 547 2003 3 549 2004 kharlov 23 000 1999 dvorovaya bay 32 330 2003 37 628 a 2005 a totals based on counts in control plots. http://www.aquarius.ifm-geomar.de/ y. v. krasnov et al. status of black-legged kittiwakes, common guillemots and brünnich’s guillemots polar research 26 2007 113 – 117 © 2007 the authors 115 common guillemot in murman, 2593 guillemots (1287 common guillemots, 40 brünnich’s guillemots and 1266 unidentified guillemots) were counted at cape gorodetskiy in 2000. five monitoring plots were defined and contained 705 common guillemots and 25 brünnich’s guillemots (or 28% of the total number of guillemots). based on repeat counts in these plots, the total population in 2002 was estimated to be 2487 individuals, of which 2400 were common guillemots (table 3). at cape krutik the guillemot population was very fragmented and spread among the kittiwake nests, and the numbers of common guillemots varied between 50 and 100 individuals. at dvorovaya the population was between 700 and 1000 individuals in 2003 and 2005, respectively. in 1999, 5800 individuals were counted at kharlov and 7000–10 000 individuals were counted at kuvshin. cape gorodetskiy, kharlov, kuvshin and dvoroyava bay are by far the four largest guillemot colonies in murman, with a total breeding population of ca. 16 000–19 000 individuals. assuming that they make up 95% of the total population, this gives a total figure of 16 500–20 000 individuals or, assuming a conversion factor of 0.6 individuals/pair (anker-nilssen et al. 2000), 9900–12 000 pairs for murman. in varanger, common guillemots were found only on hornøya and reinøya. in 1989, 1900 individuals were counted on hornøya, ca. 4000 in 1996 and ca. 6400 in 2001. based on the known rate of population increase in the colony (lorentsen 2006), the population in 2006 was estimated to be ca. 10 000 individuals. assuming the population on reinøya is 10% of that on hornøya (furness & barrett 1985), the total population for both islands in 2006 was estimated to be ca. 11 000 individuals, or 6600 pairs. brünnich’s guillemot the coasts of murman and varanger are near the southern limit of the distribution of brünnich’s guillemot, and their numbers are therefore small. at cape gorodetskiy, the precise numbers are unknown but are thought to be in the order of 70–80 individuals. at cape krutik the table 2 mean clutch sizes (excluding empty nests) of black-legged kittiwakes ( rissa tridactyla ) in colonies in varanger and along the murman coast in 1995–2005. colony hornøya cape gorodetskiy cape krutik kharlov dvorovaya bay mean se n mean se n mean se n mean se n mean se n 1995 1.78 0.02 668 — — — — — — 1.70 0.03 327 — — — 1996 1.78 0.02 838 — — — — — — 1.46 0.04 193 — — — 1998 2.11 0.02 782 — — — — — — 1.93 0.03 401 — — — 2000 1.76 0.02 844 1.15 0.04 66 1.66 0.07 53 — — — — — — 2002 2.04 0.02 787 1.17 0.02 462 1.24 0.05 90 — — — — — — 2003 1.75 0.02 660 — — — 1.32 0.05 101 — — — 1.21 0.05 67 2004 1.64 0.02 675 — — — 1.25 0.05 85 — — — 1.72 0.04 167 2005 1.86 0.02 730 — — — — — — — — — — — — n , number of nests with eggs; se, standard error of mean. fig. 2 numbers of black-legged kittiwakes ( rissa tridactyla pairs; � ) and common guillemots ( uria aalge individuals; � ) breeding on kharlov, murman, 1954–1999. 0 5 10 15 20 25 30 1955 1965 1975 1985 1995 n o . o f p a ir s ( x 1 0 0 0 ) 0 2 4 6 8 10 n o . o f in d iv . (x 1 0 0 0 ) bl.-l. kittiwake common guillemot table 3 numbers of common ( uria aalge ) and brünnich’s guillemots ( u. lomvia ) (individuals) counted in colonies along the murman coast in 1999–2005. colony u. aalge u. lomvia year cape gorodetskiy 2500 70–80 2000 2400 a 70–80 a 2002 cape krutik 105 35 2000 75 90 2002 52 76 2003 43 64 2004 kharlov 5800 — 1999 kuvshin 7000–10 000 3000–5000 1999 dvorovaya bay 1063 23 2003 682 17 2005 a totals based on counts in control plots. 116 polar research 26 2007 113 – 117 © 2007 the authors status of black-legged kittiwakes, common guillemots and brünnich’s guillemots y. v. krasnov et al. population was 50–100 individuals, and at dvorovaya bay ca. 20 individuals were counted (table 3). in 1999, 3000–5000 individuals were counted at kuvshin, and 1639 individuals were counted at kharlov. the colonies at kuvshin and kharlov constitute nearly the total brünnich’s guillemot population in murman, giving a total of 4600–6600 individuals, or ca. 3000–4000 pairs. at hornøya, ca. 600 individuals were counted in 2001. assuming that there were ca. 100 individuals on reinøya (ca. 14% of the hornøya population; furness & barrett 2005) and that there has been little change since (rtb, unpubl. data), the 2006 population on hornøya and reinøya was estimated to be on the order of 700–800 individuals, or 400–500 pairs. discussion prior to these surveys, the total kittiwake population along the murman coast was estimated to be 66 900 pairs in about 1980 (golovkin, 1984; anker-nilssen et al. 2000). apart from cape gorodetskiy, cape krutik, kharlov and dvoroyava bay, earlier studies (e.g. gerasimova 1962) documented 12 or 13 colonies with less than 5000 pairs in total. although numbers have dropped by ca. 50% in two colonies monitored in north norway since 1980 (barrett et al. in press), there is no evidence of a similar decline in kittiwake numbers in murman. at kharlov, the only colony where there has been regular monitoring since the 1960s (krasnov & barrett 1995), numbers have fluctuated between 16 000 and 28 000 pairs, but with no evidence of a population trend between 1980 and 1999 (fig. 2). thus, with a recent total figure of ca. 140 000 pairs, the former figure of 66 900 pairs for the whole of murman was probably an underestimate. this is probably partly because the former figure was based on counts made in the early 1960s (gerasimova 1962), and numbers are known to have increased at kharlov (fig. 2), sør-varanger and hornøya (krasnov & barrett 1995) since then, and hence probably also increased at other colonies in the region. in varanger, numbers have dropped since the mid 1980s in both sørvaranger and at hornøya, and the present population of 31 000–32 000 pairs is approximately half of that documented in the early 1980s (barrett 2003; barrett et al. in press). at kharlov, earlier studies showed that kittiwake clutch size was a good indicator of feeding conditions early in the breeding season. at this time capelin was the main prey, and when present in large numbers in march–may the mean clutch size (excluding empty nests) was ≥ 2.0 eggs, but when capelin was absent the mean clutch size was ≤ 1.6 eggs (barrett & krasnov 1996). data from this study show that kittiwake mean clutch sizes at cape krutik and dvorovaya bay were only once greater than 1.6, whereas at kharlov the mean clutch size reached 1.6 or more in two out of three seasons (1995 and 1998; table 2). in all cases (except at cape krutik in 2000), the mean clutch sizes were lower than at hornøya in the same years (student’s t -test, p ≤ 0.01 in all cases). furthermore, large-scale breeding failures among kittiwakes were registered at cape gorodetskiy in 2000 and 2002 when 42.1% and 50.5% of the nests, respectively, did not contain eggs, and at kharlov ca. 30% of the nests were empty in 1996 and 1998 (yvk, pers. obs.). only once, in 2002, in the eight years covered here did the number of empty nests on hornøya make up > 25% (29%) of the total nests counted (rtb, pers. obs). this suggests that feeding conditions have, in recent years, often been poor prior to egg laying for kittiwakes along much of the murman coast. despite this reduction in the initial breeding success, the murman population does not seem to have declined, whereas the population in varanger, where clutch sizes were higher, has seriously declined. anker-nilssen et al. (2000) cite 10 common guillemot colonies, totalling 20 000–30 000 pairs (or 32 000–48 000 individuals, assuming a conversion factor of 0.6 individuals/pair; anker-nilssen et al. 2000), on the murman coast. although based on single counts, and thus not taking into account the diurnal and seasonal fluctuations in numbers of birds on the breeding shelf, the surveys were made during the late incubation/hatching period when such fluctuations are at a minimum (barrett 2001), such that we are confident that the results from the present surveys in murman are within the correct order of magnitude. using the same conversion factor we estimate the total breeding population of common guillemots in murman to be 10 000–12 000 pairs, suggesting that the figure given by anker-nilssen et al. (2000) was optimistic. there are, however, several complications inherent in any comparison between the present numbers and earlier totals. many of the early counts were made from the sea, and there is a suspicion that they were underestimates. furthermore, there have been huge fluctuations in numbers of common guillemots breeding in the region, including an 85% decline (from ca. 8 000 to 1200 individuals at kharlov) in 1986/87 (krasnov & barrett 1995; krasnov et al. 1995) followed by a recovery (at kharlov to near pre-collapse levels, 6 000 individuals in 1999; fig. 2). as a result, it is difficult to determine the scale of any changes in guillemot numbers in murman, and only at dvorovaya bay is the difference between ca. 4000 pairs ( = ca. 7000 individuals) counted in the 1960s (gerasimova 1962) and the 1000 individuals in 2003–2005 (this study) large enough to be convincing of a real decline. here, there is no evidence of the rapid recovery documented in the two colonies further west (kharlov y. v. krasnov et al. status of black-legged kittiwakes, common guillemots and brünnich’s guillemots polar research 26 2007 113 – 117 © 2007 the authors 117 and hornøya) where seabirds have been regularly monitored. at cape krutik gerasimova (1962) counted 320 pairs of guillemots, whereas the present figure was a maximum of 100 pairs. the present total population of 3000–4000 pairs of brünnich’s guillemots in murman is similar to the 3000 pairs given in anker-nilssen et al. (2000), suggesting little change over recent years. with the exception of the collapse in the guillemot breeding populations at kharlov in 1986/87 (krasnov & barrett 1995), it is difficult to relate population data in murman to changes in the marine environment such as food availability. the large decline and lack of evident recovery of the common guillemot population at dvoroyaya bay may, however, be the result of poorer feeding conditions (yvk, pers. obs.), and is of concern. acknowledgements this study was partly financed by the university of tromsø, the norwegian seapop project (anker-nilssen et al. 2005) and the norwegian national monitoring programme for seabirds (lorentsen 2006). we thank yuri goryaev and aleksey ezhov for their help during field work and svein-håkon lorentsen and two referees for their comments on earlier drafts of the manuscript. references anker-nilssen t., bakken v., strøm h., golovkin a., bianki v. & tatarinkova i.p. (eds.) 2000. the status of marine birds breeding in the barents sea region . norsk polarinstitutt rapportserie 113 . anker-nilssen t., bustnes j.o., erikstad k.e., fauchald p., lorentsen s.-h., tveraa t., strøm h. & barrett r.t. 2005. seapop. et nasjonalt sjøfuglprogram for styrket beslutningsstøtte i marine områder. (seapop. a national seabird programme for improved decision support in marine areas.) nina rapport 1 . barrett r.t. 2001. monitoring the atlantic puffin fratercula arctica , common guillemot uria aalge and black-legged kittiwake rissa tridactyla breeding populations on hornøya, northeast norway, 1980–2000. fauna norvegica 21 , 1–10. barrett r.t. 2003. the rise and fall of cliff-breeding seabirds in sør-varanger, north norway, 1970–2002. fauna norvegica 23 , 35–41. barrett r.t. & krasnov y.v. 1996. recent responses to changes in stocks of prey species by seabirds breeding in the southern barents sea. ices journal of marine science 53 , 713–722. barrett r.t., lorentsen s.-h. & anker-nilssen t. in press. the status of breeding seabirds in mainland norway. atlantic seabirds . durant j.m., anker-nilssen t. & stenseth n.c. 2003. trophic interactions under climate fluctuations: the atlantic puffin as an example. proceedings of the royal society, london b 270 , 1461–1466. durant j.m., anker-nilssen t. & stenseth n.c. 2006. ocean climate prior to breeding affects the duration of the nesting period of the atlantic puffin. biology letters 2 , 628–631. frederiksen m., edwards m., richardson a.j., halliday n.c. & wanless s. 2006. from plankton to top predators: bottom-up control of a marine food web across four trophic levels. journal of animal ecology 75 , 1259–1268. furness r.w. & barrett r.t. 1985. the food requirements and ecological relationships of a seabird community in north norway. ornis scandinavica 16 , 305–313. gerasimova t.d. 1962. sostoyanie ptich’ikh bazarov murmanskogo poberezh’ya. (the status of the seashore bird colonies on the murmansk shore.) ornithology (moscow) 4 , 11–14. golovkin, a.n. 1984. seabirds nesting in the ussr: the status and protection of populations. icpb technical publication 2 , 473–486. iversen s.a., fossum p., gjøsæter h., skogen m. & toresen r. (eds.) 2006. havets ressurser og miljø 2006. (the ocean’s resources and environment.) fisken og havet, særnummer 1-2006 . krasnov j.v. & barrett r.t. 1995. large-scale interactions among seabirds, their prey and humans in the southern barents sea. in h.r. skjoldal et al. (eds.): ecology of fjords and coastal waters . pp. 443–456 amsterdam: elsevier science. krasnov y.v., matishov g.g., galaktionov k.v. & savinova t.n. 1995. morskiye kolonialniye ptitsi murmana. (the colonial seabirds of murman.) st. petersburg: nauka publishers. lorentsen s.-h. 2006. det nasjonale overvåkningsprogrammet for sjøfugl. resultater til og med hekkesesongen 2006. (the national monitoring programme for seabirds. results up to and including the 2006 breeding season.) nina rapport 203 . quillfeldt c.h. & dommasnes a. (eds.) 2005a. forslag til indikatorer og miljøkvalitetsmål for barentshavet. rapport fra et delprosjekt under forvaltningsplanen for barentshavet. (proposals for indicators and environmental quality objectives for the barents sea. report from a sub-project under the management plan for the barents sea . ) accessed on the internet at http://barentshavet.imr.no on 30 april 2007. quillfeldt c.h. & dommasnes a. (eds) 2005b. the scientific basis for environmental quality objectives (ecoqos) for the barents sea ecosystem. working group report on seabirds and marine mammals . accessed on the internet at http://barentshavet.imr.no on 30 april 2007. http://barentshavet.imr.no http://barentshavet.imr.no bookreviews25(1).indd 77polar research 25(1), 75–79 review of polarfahrer—im banne der arktis, by theodor lerner, edited by frank berger (2005). zürich: oesch verlag. 317 pp. isbn 3-0350-2014-0. in german. sebastian gerland norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, gerland@ npolar.no. theodor lerner was born 1866 in antweiler/ahr and died 1931 in frankfurt/main, where he had lived from 1911 onwards. in polarfahrer—im banne der arktis, which can be translated as “polar traveller—spellbound by the arctic”, frank berger presents lerner’s original 1930–31 manuscript. the editor has undertaken only some orthographical and grammatical alterations. lerner’s original manuscript is supplemented with (solely old) photographs, a few maps, an epilogue, a brief biography, the editor’s footnotes to the text and a list of references. the book relates lerner’s experiences during seven journeys to svalbard between 1896 and 1914. a journalist whose accounts were published in magazines and newspapers, lerner reported on the launch of salomon august andrée’s ill-fated bid to reach the north pole in a hydrogen balloon and the failed airborne expeditions of walter wellman. he participated in the rescue of herbert schröder-stranz’s expedition and the grounded tourist ship isle de france. he looked into the mining possibilities on bjørnøya and he overwintered on spitsbergen along with hjalmar johansen, who is known to many on account of his participation in expeditions led by fridtjof nansen and roald amundsen). lerner’s adventures earned him the nickname “prince of mist” in the media, because of his knack for finding his way in the fog. as a sea ice scientist with roots in the frankfurt/main area and having worked in svalbard (i also reside in tromsø, a northern norwegian coastal town that lerner passed through during his travels), i enjoyed reading this book and revisiting the adventures of famous polar explorers from a different point of view than modern retellings or memoirs by the explorers themselves. the book touches on several issues which occupy today’s researchers, such as winter warm spells in the arctic and sea ice thickness, just to name two. on the other hand, some things were astonishingly different in the early decades of the last century. the arctic ecosystem and climate processes were poorly understood compared to today, and attitudes toward, for example, property and animals (lerner describes how four polar bears captured on an expedition were transported in crates; the din they made resulted in a fine during a stop in arkhangelsk and in censure in the tromsø newspapers), contrasted markedly to modern ideas. all this makes it difficult and maybe inappropriate to raise ethical criticisms. polarfahrer is a compelling and well-written account that not only describes the expeditions themselves, but also the preparations beforehand, including attempts to find sponsors. the descriptions are lively and often flavoured with humour. what do we know about lerner from his contemporaries? as pointed out by reinke-kunze (1992), fridtjof nansen (1920) discussed critically lerner’s activities on bjørnøya, the southernmost island of the svalbard archipelago. nansen objected to the way lerner set up property boundaries using poles and rocks, claiming lerner spent the winter of 1907–08 in a cabin at kap boheman, spitsbergen. (this and other pictures in this review used with permission of the publisher.) 78 book reviews certain areas on bjørnøya as the personal property of himself and of his friend kapitän rüdiger. hjalmar johansen (1998), nansen’s partner in the famous sledge journey during the fram expedition in 1895, described overwintering with lerner in a hut at kap boheman, on the northern shore of isfjorden, spitsbergen, in terms that contrast so sharply with polarfahrer that one might think that lerner and johansen were describing two entirely different events. johansen’s diary contains many negative comments about lerner; but that is perhaps more indicative of the nature of a personal diary (as opposed to a book intended for public consumption) than of the character of lerner himself. readers of polarfahrer would have benefited from one or more modern maps illustrating travel routes and indicating place names (some of which are different than those in use today) mentioned in the text. an index of old and new place names would have made it easier to recognize and find locations featuring in lerner’s travels. the book contains a number of very interesting black and white photographs. unfortunately, the reprint quality is not very good, probably because of the paper stock. a photograph on the back of the dust jacket has reproduced significantly better than the same picture inside the book. some of the picture captions could have been more informative. not every reader would notice that it is tromsø sound in the background of the photograph of the ship the expres on p. 19 or that lerner is on deck among the 14 crewmembers pictured on p. 284. the history of polar exploration is a popular subject internationally. to be accessible to a much larger potential audience, polarfahrer should be translated into english. in that event, the editor and publishers should seize the opportunity to print the photographs on better paper and to add maps and perhaps a section of modern colour photographs of key locations to show how they look now. the cabin in which lerner and hjalmar johansen overwintered at kap boheman. the lövenskiold, trapped in the ice off nordaustlandet, svalbard, in 1912. 79polar research 25(1), 75–79 interest in lerner’s adventures persists. they provided inspiration for martin mosebach’s fictional comic novel, der nebelfürst (the prince of mist). as reported in die welt (kurth 2005), professor hans fricke recently led an attempt to locate—using a submarine—the remains of the lövenskiold, the ship which transported one of the expeditions in which lerner participated and later described in polarfahrer. in the grip of ice, the vessel had to be abandoned off the northern shore of nordaustlandet in 1912. unfortunately, fricke’s team did not locate the wreck. they surmise that it was pushed out to sea by ice, as suggested by scrape marks on the sea floor in the area where the ship is thought to have gone down. references johansen, h. 1998: dagboken fra spitsbergen 1907–08. (diary from spitsbergen 1907–08.) svalbardminner 11. skien, norway: vågemot miniforlag. kurth, n. 2005: expedition zum nördlichsten wrack der welt. (expedition to the world’s northernmost shipwreck.) die welt. accessed online at www.welt.de/data/2005/10/ 25/793558.html?s=1 on 14 november 2005. mosebach, m. 2001: der nebelfürst. (the prince of mist.) frankfurt: eichborn. nansen, f. 1920: en ferd til spitsbergen. (a journey to spitsbergen.) kristiania (oslo): jacob dybwads forlag. reinke-kunze, c. 1992: auf bruch in die weiße wildnis. die geschichte der deutschen polarforschung. (setting out for the white wilderness. the history of german polar research.) hamburg: ernst kabel verlag. vazquez.indd 63vazquez & mac cormack 2002: polar research 21(1), 63–71 enzymes constitute an important industrial product and have reached an annual marketing figure of us$ 1.6 billion. proteolytic enzymes represent nearly 60 % of this market and have a broad spectrum of applications, mainly in the food industry, laundry products and leather processing (demain 1999). as enzymes showing high catalytic efficiency under extreme environmental conditions could be useful for many purposes, extremophilic microorganisms became the centre of an important research effort conducted to obtain enzymes adapted to work under high or low temperatures, and in extremely acidic or alkaline media and high salinity (aguilar 1996). among extremophiles, psychrophilic and psychrotolerant bacteria, which are adapted to grow at 0 °c, constitute a relevant source of enzymes potentially useful in industrial processes in which working at low temperature represents an advantage (gerday et al. 2000). as the majority of the industrial proteases currently used are produced by mesophilic microorganisms and show optimum activity around 55 60 °c (kamal et al. 1995; suhartono et al. 1997; varela et al. 1997; asakawa et al. effect of isolation temperature on the characteristics of extracellular proteases produced by antarctic bacteria susana c. vazquez & walter p. mac cormack protease-producing psychrotolerant bacteria were isolated from antarctic biotopes on casein agar plates using different incubation temperatures. most of the isolates were non-spore-forming gram-negative motile rods with catalase activity, 30 % were pigmented and none of them were glucose fermenters. all the strains were grown in liquid cultures at 20 °c and protease secretion was tested using the azocasein method. despite their capacity for production of a clear zone of hydrolysis in agar plates, some strains did not produce detectable levels of proteolytic activity in liquid cultures. the lowest apparent optimum temperature for protease activity found in culture supernatants was 40 °c. almost all the strains showed activation energy values about 10 20 kj·mol-1 lower than that observed for a mesophilic subtilisin. most of the proteases showed optimal activity at neutral or alkaline ph values and developed a multiple-band profile on gelatine-sds-page. it was observed that the lower the strain isolation temperature was, the more stongly cold-adapted—in terms of optimal temperature and activation energy—were the proteases produced by them. this dependence of the characteristics of the proteases on the isolation temperature is an important factor to take into account in the design of screening programmes directed towards the isolation of psychrotolerant bacteria able to produce proteases strongly or weakly adapted to work in the cold. the antarctic area explored proved to be a promising source of proteolytic bacteria with potential use in industrial processes to be carried out at low or moderate temperatures. s. c. vazquez, cátedra de microbiología industrial y biotecnología, facultad de farmacia y bioquímica, universidad de buenos aires, junín 956 6º piso (1113) buenos aires, argentina; w. p. mac cormack, instituto antártico argentino, departamento de biología, cerrito 1248 (1010) buenos aires, argentina. 64 proteases from antarctic bacteria 65vazquez & mac cormack 2002: polar research 21(1), 63–71 1998; han & damodaran 1998), there is a general interest to find new proteases with lower optimum temperatures, which would result in a considerable energy saving (horikoshi 1995; aguilar 1996). in antarctica, one of the coldest areas in the world, prokaryotes are the dominant organisms and they are mainly responsible for the hydrogeochemical cycles and the mineralization of organic matter (karl 1993; rivkin et al. 1996). in addition, the antarctic continent is one of the less explored places on earth and accounts for the high proportion of new taxa that are described when biochemical and molecular techniques are applied to the analysis of bacteria present in samples taken from these environments (irgens et al. 1996; reddy et al. 2000). therefore, antarctica is one of the most promising sources of new bacterial isolates able to produce cold-adapted proteases with lower optimum temperature than those currently used in industry. environments in the antarctic peninsula are exposed to different temperature ranges. some of them, such as soil and rock surfaces, are exposed to significant solar irradiation and show a broad range of temperatures which extends from below the freezing point to over 25 °c (vishniac 1993). on the other hand, environments such as seawater, marine sediments and sea ice have constant temperature values lower than 4 °c (schloss et al. 1998). antarctic microorganisms’ ecophysiological and biochemical adaptations could be reflecting the different temperature regimes they have to withstand. it is known that isolation temperature strongly influences the psychrophilic/psychrotolerant ratio of the bacteria isolated from a sample (delille & perret 1989; delille 1992). thus, even among the psychrotolerant bacteria, a low isolation temperature could determine a higher probability to obtain strains with low optimum temperature not only for growth but also for the activity of their extracellular enzymes. although cloning of the genes involved in protease production could be a necessary step in the optimization of the production process at industrial scale, the screening of new strains and the characterization of the proteases produced by them represent an important initial activity. since, from a biotechnological point of view, an industrial process based on psychrotolerant bacteria is more simple and cost-efficient than one based on psychrophiles, the influence of the isolation temperature on the optimum temperature for growth and protease activity is an important point to consider to improve the search for this kind of strains. in the present work, our aim was to isolate neutral or alkaline protease-producing psychrotolerant bacteria from antarctic environments and compare the effect that isolation temperature has on the basic properties of these extracellular proteases. materials and methods sampling area the samples were taken during argentine summer antarctic research expedition (are) 1995–96 near jubany scientific station (62° 14’ s, 58° 40’ w) on king george island, south shetland islands. samples were collected from soil, fresh and marine waters, marine sediments and remains of organic matter of animal and plant origin. in addition, strains isolated during the are 1991–92 (vazquez et al. 1995) were included for comparison and further study. screening and isolation of psychrotolerant bacterial strains samples from soil and organic matter were placed in a screw-capped bottle containing 5 g of sterile sand and 15 ml of sterile diluent (1 g·l-1 of peptone solution) and shaken for 15 min. after shaking, serial 10-fold dilutions were prepared in the same diluent and 0.1 ml of each dilution was spread on the surface of nutrient agar plates (merck) for counting total heterotrophic bacteria. proteolytic bacteria were screened by spreading 0.1 ml of dilutions on casein agar plates at ph 7.0, in accordance with hoshino et al (1997). proteolytic activity was detected as clear zones of hydrolysis around the colony. samples from marine origin were processed in the same way but diluent and media were prepared using 75 % v/v seawater. samples were incubated at 20 °c and at 4 6 °c for 20 days, in order to further analyse the effect of incubation temperature on the characteristics and growth of the isolated strains and on the activity of the proteases produced by them. different proteolytic colonies were isolated and purified by re-streaking twice. general characteristics of previously obtained proteolytic strains isolated at 10 13 °c during are 1991–92 (vazquez et 64 proteases from antarctic bacteria 65vazquez & mac cormack 2002: polar research 21(1), 63–71 al. 1995) are included for comparison in the results section. characterization of bacterial strains all proteolytic bacteria were characterized from 48 h old pure cultures grown at 20 ºc. the strains were gram stained and shape and size of the cells were examined under the light microscope. their mobility was investigated in hanging drops. the colour of the colonies was observed on nutrient agar plates. catalase, cytochrome oxidase activity and aerobic and anaerobic utilization of glucose (hugh-leifson medium) were also tested. liquid culture conditions growth experiments were performed in nutrient broth (oxoid cm1) supplemented with 0.3 g·l-1 cacl2.2h2o, ph 8.0. for marine strains the medium was re-hydrated with 100 % v/v artificial seawater (lyman & fleming 1940). experiments were carried out in 300 ml erlenmeyer flasks with 60 ml of medium and incubated in a rotatory shaker at 240 rpm at 20 °c. inocula were grown in the same medium, adjusted to an optical density at 580 nm (od580) of 0.100 and added to broth at 1 % v/v proportion (final od under the detection limit). samples were taken after 24, 48 and 72 h of incubation and used to measure growth, ph and proteolytic activity. all the experiments were performed in duplicate. growth was monitored by measuring the od580 of the samples in an uv-visible spectrophotometer and expressed as dry weight using previously tested calibration curves. dry weight was determined (in triplicate) by weighting the dried biomass (48 h at 105 °c) after centrifugation of aliquots of the culture. protease assay proteolytic activity was measured by digestion of azocasein, in accordance with charney & tomarelli (1947). an appropriate dilution of culture supernatant (400 µl) was incubated with 400 µl of 1 % w/v azocasein in 0.1 m tris/hcl buffer (ph 8.0) and 0.5 mm cacl2.2h2o at 20 °c for 30 min. the reaction was stopped by adding 800 µl of 5 % w/v trichloroacetic acid. after centrifugation of the reaction mixture, absorbance of the supernatant was measured at 340 nm. samples were assayed in duplicate and the activity was expressed in relative enzymatic units (eu). one eu was defined as the amount of enzyme that produces an increase of 0.100 in a340 under the assay conditions. effect of ph and temperature on activity of proteases the effect of ph and temperature on protease activity was determined by using the protease assay described above. determination of the optimum ph was performed at 20 °c with the following buffer systems (0.1 m each): kh2po4/na2hpo4 (ph 5 7); tris/hcl (ph 8 9) and na2hpo4/ naoh (ph 10 12). for determination of the optimum temperature, the reaction was carried out at different incubation temperatures (between 0 °c and 60 °c) and ph 8.0. activation energies were calculated from the linear part of arrhenius plots as described by pirt (1985). polyacrilamide gels extracellular protease profiles were analysed by sds-page minigels containing gelatine as copolymerized substrate (heussen & dowdle 1980). proteolytic activity was evident as bands depleted of gelatine. results even though we sampled in biological systems where natural changes in the bacterial population make comparison among samples difficult, a common pattern was observed (table 1). samples from ecosystems exposed to wide thermal oscillation (like soil surface and organic matter exposed to solar radiation) showed higher total bacterial counts at 20 °c when compared with those obtained at 4 °c. conversely, samples taken from areas subjected to low and almost constant temperature (like seawater or marine sediments) had lower counts at 20 °c than at 4 °c. the number of gram-positive strains varied with the different isolation temperatures, corresponding to 6 14 % when the isolation was made at 13 °c or lower, but rising to 40 % when the strains were isolated at 20 °c. the presence of spore-forming bacteria was observed when the screening was carried out at 20 °c (table 2) but they were not isolated at 4 °c, probably because this temperature was not suitable for the germination of the spores which were likely to be present. 66 proteases from antarctic bacteria 67vazquez & mac cormack 2002: polar research 21(1), 63–71 on the basis of the formation of a clear zone in casein agar, 89 proteolytic strains (40 isolated at 20 °c and 49 at 4 6 °c) were selected. in table 2, we summarize the general characteristics of the selected protease-producing psychrotolerant strains isolated during are 1995–96 and of other strains previously isolated during are 1991–92 (vazquez et al. 1992). all the strains were capable of growth at 0 °c but had an optimum growth temperature higher than 15 °c, corresponding to psychrotolerant microorganisms (morita 1975). the majority of them were non-spore forming gram-negative rods, though some strains were gram variable. this was probably due to the presence of certain components on their cell walls which may interfere with the cell permeability to the stain. the pigmented strains (30 % of total isolates) were mostly yellow and orange coloured. motile strains with cytochrome oxidase activity predominated. almost all the strains had catalase activity and none of them were glucose fermenters. when all the newly-isolated 89 proteolytic strains plus the 34 additional strains selected in a previous screening were cultured in nutrient broth, some showed a protease secretion pattern associated with growth (fig. 1b), while other strains presented their enzyme secretion partially associated with growth (starting at the early stationary phase) or not associated with growth at all (fig. 1a). some strains were discarded for further stud fig. 1. examples of two different patterns of growth and protease production kinetics observed in the selected antarctic strains. when strains were cultivated in liquid culture, protease production showed two different behaviours. (a) protease secretion delayed with respect to growth, starting at the early stationary phase (p-96-34). (b) enzyme secretion associated with growth (p95-16). (a) (b) table 1. heterotrophic bacterial counts incubated at 20 °c and 4 6 °c from different samples taken during summer antarctic research expedition 1994–95. sample origin ph cfua 20 °c 4 6 °c lichens (usnea antarctica) 5.5 1.8·106 ± 5.1·104 1.0·105 ± 4.5·104 moss mat (near pond coast) 6.0 4.3·106 ± 4.6·105 3.0·104 ± 4.5·103 dead elephant seal skin (potter cove coast) ndb 4.0·106 ± 4.9·105 3.5·104 ± 4.1·103 seawater (potter cove) surface 7.8 1.2·102 ± 6.9·10 3.8·103 ± 6.9·102 5 m deep 7.9 7.6·101 ± 7.0·10 2.9·103 ± 6.5·102 10 m deep 7.9 8.3·101 ± 6.2·10 3.1·103 ± 6.0·102 20 m deep 7.8 3.5·102 ± 1.5·101 2.7·103 ± 3.4·102 30 m deep 7.8 1.2·102 ± 9.0·10 2.9·103 ± 5.4·102 soil (near fourcade glacier) ndb 2.6·105 ± 4.1·104 1.0·104 ± 3.7·103 algae (desmarestia antarctica) 7.0 5.0·105 ± 5.3·104 4.6·105 ± 5.7·104 sediment pond (1 m deep) 7.2 7.5·103 ± 7.4·102 1.7·103 ± 5.7·102 potter cove (30 m deep) 7.7 5.9·103 ± 7.0·102 2.4·104 ± 4.1·103 a colony forming units of the cultivable heterotrophic bacteria expressed as gram of dry weight except for the seawater samples, which are expressed as ml of sample. b not determined. 66 proteases from antarctic bacteria 67vazquez & mac cormack 2002: polar research 21(1), 63–71 ies, as they showed no proteolytic activity at any time in liquid culture, measured by the azocasein method. after centrifugation of cells, the proteases present in culture broth supernatants were partially characterized. when the strains isolated at 20 °c were tested, only 14 % of cell-free supernatants showed optimal activity at 40 °c (the lowest apparent optimum temperature found). nevertheless, when the strains were isolated at 10 13 °c or at 4 6 °c, the percentages raised to 28 % and 46 %, respectively (table 2). on the basis of their apparent optimum temperature for substrate utilization (table 3), 25 protease-containing culture supernatants were selected. the isolation temperature of the 25 protease-producing strains is indicated in table 4. these supernatants showed their maximal activity at 40 °c (table 3) and contained neutral and alkaline proteases with regards to their optimum ph for activity (table 4). the activation energy values for proteolytic activity were, in general, about 10 20 kj·mol-1 lower than those observed for the mesophilic protease carlsberg subtilisin (table 3). the development of proteolytic activity of culture supernatants on sds-page with gelatine as a copolymerized substrate showed mainly multiple-band profiles. among the 25 protease-containing supernatants with the lowest optimum temperature, only 8 developed a single proteolytic band. discussion microbiological studies related to antarctic environments are frequently focused on the role of the bacterial community in heterotrophic production, in the cycling of matter, or in the relationship between bacterial activity and the dynamics of food webs. however, the majority of these studies do not discriminate between the different groups of bacteria that constitute the total flora responsible for one particular activity. when analyses of the bacterial flora of particular antarctic environments were carried out, gram-negative bacteria proved to be highly predominant in marine habitats (delille 1993), coastal zones (tearle & richard 1987; line 1988) and terrestrial habitats covered with vegetation (heal et al. 1967). this is consistent with the results presented here and could explain the fact that, in spite of the known capacity of gram-positive bacteria to produce and secrete proteases, few of the selected strains were gram-positive. among marine isolates, gram-positive bacteria were found mostly in sediments while among non-marine isolates they were predominant in soil, mosses and lichens. also, the number of spore-forming and pigmented strains was higher when the incubation temperature was 20 °c. the predominance of these strains during the summer could be reflecting their capability to withstand the relatively high temperatures and levels of uv radiation that prevail in this period, especially taking into account that the explored area is affected by the thinning of the ozone layer during spring and summer (tong & lighthart 1997). it is worth mentioning that most microorganisms, especially in aquatic environments, are not culturable on conventional agar media and using conventional techniques. the considerations expressed above relate to the part of the bacterial community that can be isolated with the culture conditions used, corresponding to the aerobic chemoorganotrophic psychrophilic and psychrotolerant culturable bacteria. the differences observed in the total counts obtained at 4 6 °c and at 20 °c with samples from environments having broad and narrow ranges of temperature reflect the different degrees of adaptation showed by bacteria living in antarctic areas with or without thermal oscillations. table 2. characteristics of the psychrotolerant antarctic proteolytic bacteria, collected during two antarctic research expeditions (are), isolated on casein agar using three different incubation temperatures. are 1995–96 are 1991–92 are 1995–96 isolation isolation isolation 20 °c 10 13 °c 4 6 °c pigmented strains 40 % 15 % 22 % spore-forming 13 % 1 % 0 % form rod-shaped 87 % 97 % 88 % cocci-shaped 13 % 3 % 2 % gram stain positive 40 % 6 % 14 % negative 60 % 94 % 86 % detection of proteases in liquid culture at 20 ºc 53 % 73 % 67 % optimum temperature for proteolytic activity 40 °c 14 % 28 % 46 % 45 °c 29 % 7 % 46 % >50 °c 57 % 65 % 8 % number of isolated strains 40 34 49 68 proteases from antarctic bacteria 69vazquez & mac cormack 2002: polar research 21(1), 63–71 since psychrotolerants grow faster at 20 °c than at 4 °c and we previously tested that the incubation time was long enough to allow the development of psychrophiles and psychrotolerants colonies, the higher counts obtained with non-marine samples when the incubation was made at 20 °c might be related to the predominance of this type of microorganism in areas with a wide daily and seasonal variations in temperature (delille 1990). on the contrary, with seawater and marine sediment the counts obtained at 4 °c were higher than those obtained at 20 °c, reflecting the appropriateness of these constantly cold environments for the predominance of psychrophiles. the selected strains showed variable proteolytic activity levels in liquid cultures. even when some of the proteases from psychrotolerants had their maximal activity at similar temperatures than their corresponding mesophile, the majority of them showed curves of activity as a function of temperature shifted towards low temperatures, with apparent optimum values between 10 and 15 °c lower than carlsberg subtilisin. other authors found similar results for proteases (helmke & weyland 1991; turkiewicz et al. 1999) and other enzymes (feller et al. 1997; hoyoux et al. 2001) produced by marine bacteria from permanently cold environments. this observation reveals a clear adaptation of the enzyme-producing strains to their habitats. the low activation energies shown by many of the crude proteases also represents a way of adaptating to work in the cold and constitute a requirement for substrate hydrolysis in cold environments and, thus, for survival (margesin et al. 1991; feller & gerday 1997). these enzymes compensate the low kinetic energy in their environments by reducing the activation energy barrier. in addition, all proteases with the lower optimum temperature (40 °c) had a neutral or alkaline optimum ph, probably influenced for the neutral ph of the isolation culture media or the ph of the habitats explored. although the broad ph range in which some of our proteases showed maximum activity agree with the ones reported for other cold-adapted proteases (hamamoto table 3. optimum temperature (ot), percent of relative activity measured at 20 °c with respect to the activity at optimum temperature (ra) and activation energy for azocasein hydrolysis (eact) of crude proteases from 79 antarctic psychrotolerant strains. strain ot ra eact strain ot ra eact strain ot ra eact (°c) (%) (kj·mol-1) (°c) (%) (kj·mol-1) (°c) (%) (kj·mol-1) ele-2 40 34 40 p95-8 45 17 45 p96-20 45 21 51 ele-3 40 19 54 p95-9 45 22 46 p96-23 45 19 47 tcn-2 45 13 51 p95-16 45 20 49 p96-27 45 14 55 gud-5 50 12 50 p95-17 45 26 49 p96-28 45 9 52 gud-8 50 17 52 p95-18 45 29 49 p96-29 40 29 53 ant-1-1 55 6 55 p95-19 45 24 44 p96-33 40 21 52 ant-3-1 50 6 50 p95-20 >50 12 52 p96-35 40 35 40 ant-7-1 55 6 55 p95-21 >50 25 47 p96-37 50 22 46 yoa-3 60 5 60 p95-24 40 30 36 p96-38 45 37 39 814 40 32 40 p95-27 40 10 52 p96-39 45 34 42 piel-1 40 29 40 p95-28 >50 10 52 p96-41 40 14 54 91 50 35 50 p95-29 >50 21 38 p96-43 40 31 47 435 50 30 50 p95-31 >50 27 33 p96-44 50 26 38 337 50 9 50 p95-32 >50 9 55 p96-45 45 14 50 273 50 13 50 p95-33 >50 13 41 p96-46 45 7 55 a1 50 6 50 p95-37 >50 25 51 p96-47 45 27 47 prot-2 50 17 50 p95-38 >50 15 49 p96-48 45 21 50 prot-4 50 20 50 p95-39 >50 19 55 p96-49 40 23 50 prot-5 45 18 45 p95-40 >50 9 48 p96-50 40 35 48 prot-8 40 34 40 p96-1 45 30 37 p96-51 40 16 87 prot-9 40 13 40 p96-3 45 28 38 p96-52 40 22 74 prot-10 50 11 45 p96-4 45 29 39 p96-53 40 24 55 prot-11 40 14 40 p96-5 40 23 48 p96-54 40 22 76 prot-12 55 7 55 p96-6 50 11 52 p96-55 45 40 29 prot-14 45 29 45 p96-7 40 33 51 p96-56 45 21 49 p95-1 40 21 42 p96-12 40 13 51 p95-6 40 15 47 p96-18 40 24 50 subtilisin 55 12 60 68 proteases from antarctic bacteria 69vazquez & mac cormack 2002: polar research 21(1), 63–71 et al. 1994), this characteristic differs from that observed by other authors for low-temperature active proteases (davail et al. 1994; kärst et al. 1994) where a discrete value of optimum ph was found. in other cases, even though a discrete optimum ph value was reported, there was a broad range where the proteases showed more than 80 % of their maximum activity (margesin & schinner 1992). the ph values for maximum activity of the studied proteases make them suitable for use in detergents and other industrial products requiring alkaline proteases, though the stability of the proteases at the ph of such products and processes must be confirmed. by developing proteolytic activity of culture supernatants on gelatine-sds-page, it was possible to observe that some strains produced only one protease. these strains were selected for further studies (when their optimum temperature for activity was of interest) because they are easier to purify and characterize than a mixture of proteins. however, the majority of the strains produced a multiple-band profile, which might have been the result of the activity of more than one protease produced by the strain, isoenzymes or the active fragments of self-digestion. the synthesis of more than one protease, which was observed mainly in marine strains, could be understood as a strategy to better cope with the fluctuating supply of nutrients as well as to enhance the uptake of proteins in oligotrophic environments. although references to the number of proteolytic bands developed in sds-page from the culture supernatants of cold-adapted bacteria are infrequent in the literature, turckiewicz et al (1999) recently found two different protein bands active against denatured haemoglobin working with an antarctic marine strain of sphingomonas paucimobilis. given the relatively high cost and complexity of biotechnological processes based on the culture of psychrophiles, which must be kept very cool, psychrotolerant organisms will be more suitable than psychrophiles to support an enzyme production process at moderate temperatures (20 25 °c) while producing enzymes with high activity at low temperatures. such a process would yield an enzyme with considerable activity at temperatures significantly lower than those shown by the enzymes currently in use. on the basis of this concept, we chose 20 °c as the more suitable temperature to cultivate and produce proteases. we consider that this is an adequate temperature to carry out a process in a template climate zone, as it can be maintained without expending costly energy in cooling the reactor. we also point out the relevance of selecting the proper conditions when designing a screening programme for the selection of proteolytic bacteria in the explored area. isolation temperature was shown to be an important factor to take into account to direct the screening towards the isolation of bacteria producing the desired type of proteases. to conclude, the results presented here suggest that the selected psychrotolerant strains are potentially useful for industrial applications, and that further studies will be necessary to optimize the natural capability of these strains to produce and secrete proteases. moreover, we would like to emphasize the relevance of the antarctic environment as a source of psychrotolerant microorganisms whose physiological characteristics are often unusual in comparison to the corresponding mesophiles (shivaji et al. 1989) and which offer new possibilities in biotechnology. acknowledgements.—this study was supported by the instituto antartico argentino and the universidad de buenos aires (grant fa 059). we wish to thank c. ferreiro for correcting the english manuscript. references aguilar, a. 1996: extremophile research in the european union: from fundamental to industrial applications. fems table 4. ph values for maximal activity of crude proteases from antarctic strains showing optimum temperature for proteolytic activity at 40 °c. strain ph strain ph ele-2*,1 8 p96-18*,3 7 9 ele-31 8 11 p96-293 7 9 prot-81 8 9 p96-333 8 prot-9*,1 6 11 p96-35*,3 7 9 prot-11*,1 8 p96-413 7 9 8141 8 9 p96-433 7 9 piel-11 8 9 p96-493 8 p95-1*,2 7 9 p96-503 9 p95-21*,2 7 9 p96-513 8 p95-24*,2 7 10 p96-523 8 10 p96-53 8 p96-533 7 9 p96-73 9 p96-543 9 p96-123 7 *single proteolytic band developed in gelatin-sds-page. 1,2,3 strain isolated at 10 13 ºc, 20 ºc and 4 6 ºc, respectively. 70 proteases from antarctic bacteria 71vazquez & mac cormack 2002: polar research 21(1), 63–71 microbiol. rev. 18, 89–92. asakawa, m., sadakata, y., araki, t., sumi, t. & nakagawa, h. 1998: purification and characterization of the alkaline serine protease produced by bacillus sp. n4 strain from fish skin mucus. fish. sci. 64, 793–797. charney, j. & tomarelli, r. m. 1947: a colorimetric method for the determination of the proteolytic activity of duodenal juice. j. biol. chem. 171, 501–507. davail, s., feller, g., narinx, e. & gerday, c. 1994: cold adaptation of proteins. purification, characterization, and sequence of the heat labile subtilisin from the antarctic psychrophile bacillus ta41. j. biol. chem. 269, 1–6. delille, d. 1990: seasonal changes of sub-antarctic heterotrophic bacterioplankton. arch. hydrobiol. 119, 267–277. delille, d. 1992: marine bacterioplankton at the weddel sea ice edge, distribution of psychrophilic and psychrotrophic populations. polar biol. 12, 205–210. delille, d. 1993: seasonal changes in the abundance and composition of marine heterotrophic bacterial communities in an antarctic coastal area. polar biol. 13, 463–470. delille, d. & perret, e. 1989: influence of temperature on the growth potential of southern polar marine bacteria. microbiol. ecol. 18, 117–123. demain, a. l. 1999: stunning achievements of industrial microbiology. asm news 65, 311–316. feller, g. & gerday, c. 1997: psychrophilic enzymes: molecular basis of cold adaptation. cell. mol. life sci. 53, 830– 841. feller, g., zekhnini, z., lamotte-brasseur, j. & gerday, c. 1997: enzymes from cold-adapted microorganisms. the class c β-lactamase fron the antarctic psychrophile psychrobacter immobilis a5. eur. j. biochem. 244, 186–191. gerday, c., aittaleb, m., bentahir, m., chessa, j. p., claverie, p., collins, t., d’amico, s., dumont, j., garsoux, g., georlette, d., hoyoux, a., lonhienne, t., meuwis, m. a. & feller, g. 2000: cold-adapted enzymes: from fundamentals to biotechnology. trends biotechnol. 18, 103–107. hamamoto, t., kaneda, m., horikoshi, k. & kudo, t. 1994: characterization of a protease from a psychrotroph, pseudomonas fluorescens 114. appl. environ. microbiol. 60, 3878–3880. han, x. q. & damodaran, s. 1998: purification and characterization of protease q: a detergentand urea-stable serine endopeptidase from bacillus pumilus. j. agric. food chem. 46, 3596–3606. heal, o. w., bailey, a. d. & latter, p. m. 1967: bacteria, fungi and protozoa in signy island soils compared with those from a temperate moorland . philos. trans. r. soc., lond., ser. b252, 191–197. helmke, e. & weyland, h. 1991: effect of temperature on extracellular enzymes occurring in permanently cold marine environments. in g. rheinheimer et al. (eds): distribution and activity of microorganisms in the sea. proceedings of the 4th european marine microbiology symposium. kiel, 1990. pp. 198–204. institute for marine research, university of kiel. heussen, c. & dowdle, e. b. 1980: electrophoretic analysis of plasminogen activators in polyacrilamide gels containing sodium dodecyl sulfate and copolymerised substrates. anal. biochem. 102, 196–202. horikoshi, k. 1995: discovering novel bacteria, with an eye to biotechnological applications. curr. opin. biotechnol. 6, 292–297. hoshino, t., ishizaki, k., sakamoto t., kumeta, h., yumoto, i., matsuyama, h. & ohgiya, s. 1997: isolation of a pseudomonas species from fish intestine that produces a protease active at low temperature. lett. appl. microbiol. 25, 70–72. hoyoux, a., jennes, i., dubois, p., genicot, s., dubail, s., françois, j. m., baise, e. feller, g. & gerday, c. 2001: cold-adapted β-galactosidase from the antarctic psychrophile pseudoalteromonas haloplanktis. appl. environ. microbiol. 67, 1529–1535. irgens, r. l., gosink, j. j. & staley, j. t. 1996: polaromonas vacuolata gen. nov., sp. nov., a psychrophilic, marine, gas vacuolate bacterium from antarctica. int. j. syst. bacteriol. 46, 822–826. kamal, m., hoeoeg, j. o., kaiser, r., shafgat, j., razzaki, t., zaidi, z. h. & joernvall, h. 1995: isolation, characterization and structure of subtilisin from a thermostable bacillus subtilis isolate. febs lett. 374, 363–366. karl, d. m. 1993: microbial processes in the southern oceans. in e. i. friedman (ed.): antarctic microbiology. pp. 1–63, new york: wiley press. kärst, u., woehl, m., czempinski, k. & schmid, r. d. 1994: characterization of extracellular hydrolases from marine psychrophilic bacteria. in l. alberghina et al. (eds.): progress in biotechnology: proceedings of the 6th european congress on biotechnology. florence, 1993. pp. 263–266. amsterdam: elsevier science. line, m. a. 1988: microbial flora of some soils of mawson base and the vestfold hills, antarctica. polar biol. 8, 421– 427. lyman, j. & fleming, r. h. 1940: composition of seawater. j. mar. res. 3, 134–146. margesin, r., palma, n., knauseder, f. & schinner, f. 1991: proteases of psychrotrophic bacteria isolated from glaciers. j. basic microbiol. 31, 377–383. margesin, r. & schinner, f. 1992: a comparison of extracellular proteases from three psychrotrophic strains of pseudomonas fluorescens. j. gen. appl. microbiol. 38, 209–225. morita, r. y. 1975: psychrophilic bacteria. bacteriol. rev. 39, 144–167. pirt, s. j. 1985: effects of temperature. in s. j. pirt (ed): principles of microbial and cell cultivation. pp. 137–142. london: blackwell. reddy, g. s. n., aggarwal, r. k., matsumoto, g. i. & shivaji, s. 2000: arthrobacter flavus sp. nov., a psychrophilic bacterium isolated from a pond in mcmurdo dry valley, antarctica. int. j. syst. evol. microbiol. 50, 1553–1561. rivkin, r. b., anderson, m. r. & lajzerowicz, c. 1996: microbial processes in cold oceans. i: relationships between temperature and bacterial growth rate. aquat. microb. ecol. 10, 243–254. schloss, i., ferreyra, g. & klöser, h. 1998: seasonal variation of the conditions for phytoplankton growth in potter cove. ber. polarforsch. 299, 59–66. shivaji, s., shyamala, r. n., saisree, l., sheth, v., reddy, g. s. n. & bhargava, p. h. 1989: isolation and identification of pseudomonas spp from schirmacher oasis, antarctica. appl. environ. microbiol. 55, 767–770. suhartono, m. t., satiawihardja, b., widjaja, i. p. n. & handoko, t. w. t. 1997: characterization of protease enzyme produced from bacillus pumilus y1 isolated from liquid tofu waste. asian pac. j. mol. biol. biotechnol. 5, 72–80. tearle, p. v. & richard, k. j. 1987: ecophysiological grouping of antarctic environmental bacteria by api20 and fatty acid fingerprints. j. appl. bacteriol. 63, 497–503. tong, y. & lighthart, b. 1997: solar radiation in shown to 70 proteases from antarctic bacteria 71vazquez & mac cormack 2002: polar research 21(1), 63–71 select for pigmentation bacteria in the ambient outdoor atmosphere. photochem. photobiol. 65, 103–106. turkiewicz, m., gromek, e., kalinowska, h. & zielinska, m. 1999: biosynthesis and properties of an extracellular metalloprotease from the antarctic marine bacterium sphingomonas paucimobilis. j. biotechnol. 70, 53–60. varela, h., ferrari, m. d., belobrajdic, l., vazquez, a. & loperena, m. l. 1997: skin unhairing proteases of bacillus subtilis: production and partial characterization. biotechnol. lett. 19, 755–758. vazquez, s. c., rios merino, l. n., mac cormack, w. p. & fraile, e. r. 1995: protease-producing psychrotrophic bacteria isolated from antarctica. polar biol. 15, 131–135. vishniac h. s. 1993: the microbiology of antarctic soils. in: e. i. friedmann (ed.): antarctic microbiology. pp. 292–341. new york: wiley-liss press. doi:10.3402/polar.v32i0.18610 r e s e a r c h / r e v i e w a r t i c l e impacts of winter feeding of reindeer on vegetation and soil in the sub-arctic: insights from a feeding experiment minna turunen,1 pirita oksanen,1 terhi vuojala-magga,1 inkeri markkula,1 marja-liisa sutinen2 & juha hyvönen 2 1 arctic centre, university of lapland, p.o. box 122, fi-96101 rovaniemi, finland 2 finnish forest research institute, rovaniemi research unit, p.o. box 16, fi-96301 rovaniemi, finland keywords reindeer herding; supplementary winter feeding; sub-xeric heath forest; forage. correspondence minna turunen, arctic centre, university of lapland, p.o. box 122, fi-96101 rovaniemi, finland. e-mail: minna.turunen@ulapland.fi abstract the overall impacts of winter feeding, including the effects of both forage and reindeer (rangifer tarandus), were studied in an experiment in the hammastunturi herding cooperative (688n), finland, with 300 reindeer in a sub-xeric heath forest (35 ha) during march/april 2009 and 2010. the feeding practices on the 50 plots were: (1) feeding with grass silage�hay with leftovers cleared in the spring; (2) feeding with grass silage�hay with leftovers not cleared; and (3) feeding with pellets. in addition, (4) unfenced and (5) fenced control plots were included, on which the reindeer were not fed. no invasive plant species introduced through grass silage�hay were observed on the plots. the coverage of deschampsia flexuosa increased on grass silage�hay plots after the first winter, and both coverage and height of the grass increased after the second winter. the coverage of dicranum sp. and pleurozium schreberi was lower on plots where reindeer were fed with grass silage (leftover silage not cleared) vs. controls. some dwarf shrubs, e.g., calluna vulgaris, showed a similar response after the second winter. the n content of empetrum nigrum was higher on grass silage plots (leftover silage not cleared) after the first winter vs. controls. after two winters, the n content of both e. nigrum and vaccinium myrtillus was increased. of the soil variables studied, c/n decreased on grass silage�hay plots vs. fenced controls. we conclude that even a moderate level of feeding may cause changes that can lead to a gradual shift from nutrient-poor heath forest towards a more nutrient-rich type. in northern fennoscandia and north-west russia, reindeer herding has been affected in recent decades by such socio-economic changes as mechanization, supplementary winter feeding, regulations regarding meat production and parasite medication (jernsletten & klokov 2002; forbes et al. 2006; tyler et al. 2007). in addition, the quality and extent of pasture have declined considerably owing to, among other factors, competing forms of land use, such as forestry, industrial development, construction, mining and tourism, as well as overgrazing caused by the increased number of animals (kumpula et al. 2009; mattila & mikkola 2009). furthermore, pressures exist to increase supplementary winter feeding: higher reindeer densities and inadequate pasture rotation systems have impaired the quality of winter pastures, and the predicted fluctuations in winter weather and snow conditions may well reduce the availability of natural forage (putkonen & roe 2003; nieminen 2010; callaghan et al. 2011; hansen et al. 2011). a changing climate can have both positive and negative impacts on the availability and quality of reindeer forage (weladji & holland 2006; tyler et al. (page number not for citation purpose) to access the supplementary material for this article, please see the supplementary files under article tools online. polar research 2013. # 2013 m. turunen et al. this is an open-access article distributed under the terms of the creative commons attribution-noncommercial 3.0 unported license (http://creativecommons.org/licenses/by-nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 http://www.polarresearch.net/index.php/polar/rt/suppfiles/18610/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/18610/0 http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 2007; moen 2008; turunen et al. 2009; tømmervik et al. 2012). it has been predicted that the northern latitudes will become warmer and wetter, especially during autumn, winter and spring. increasing winter temperatures and temperature fluctuations will lead to more frequent snowmelt, rain-on-snow events and freeze* thaw cycles, which in turn causes compaction of the snow pack, formation of ice layers above and within the snow cover, and ice encasement (putkonen & roe 2003; solomon et al. 2007; callaghan et al. 2011). icing and variations in the thickness of the snow cover may worsen the conditions under which reindeer dig for forage and thereby increase their energy expenditure. in fact, decreased availability of winter forage may be one reason for the deterioration observed in the condition of animals and for low calving percentages (helle & kojola 2008; hansen et al. 2011; vuojala-magga et al. 2011). in finland, supplementary winter feed consists primarily of hay, grass silage, grain-based commercial pellets or a combination of these. during the period 2007�08, 18 million kg of pellets and over 40 million kg of hay�grass silage (calculated as dry hay) were used for feeding (nieminen 2010). in the central and northern parts of the reindeer herding area, field feeding is more common than pen feeding, with more than 60% of all animals being fed in the field. field feeding is always based partly on natural pastures; in pens reindeer get all or at least most of the forage from the herder. supplementary feeding has made it possible to keep the number and condition of reindeer stable despite difficult winter weather and snow conditions (åhman & danell 2006; nieminen 2010). a female reindeer in good condition after the winter will normally give birth to a healthy calf and be able to take care of it well (eloranta & nieminen 1986). the calves of reindeer fed with supplementary forage are heavier than those of reindeer that forage only on natural pastures (säkkinen et al. 1999; maijala & nieminen 2001). yet, winter feeding may increase the risk of diseases (oksanen et al. 1997; tryland et al. 2001; aschfalk et al. 2003). it may also intensify the widely reported direct impacts of reindeer grazing on and trampling winter pasture vegetation*reduced lichen cover in particular*as well as the indirect impacts on soil processes, for example, c and n mineralization and organic matter decomposition, which greatly depend on the site type and grazing intensity (väre et al. 1995; olofsson et al. 2001; olofsson & oksanen 2002, 2005; olofsson et al. 2004; pajunen et al. 2008; moen et al. 2009; kumpula et al. 2011). to our knowledge, the ecological impacts of winter feeding of reindeer on vegetation and soil have not been studied earlier. the aim of this investigation was therefore to study the overall impacts of supplementary winter feeding on vegetation and soil in a sub-xeric heath type forest in northern finland (688n). our main focus was to study the potential changes in species coverage in the fieldand ground-layer vegetation as well as the n content of dwarf shrubs and soil. in this study, ‘‘the overall impacts of winter feeding’’ include the effect of both forage (grass silage, hay, pellets) and reindeer activity in the form of grazing, trampling, digging and droppings. we proceeded on the basis of three hypotheses. first, winter feeding causes changes in the species coverage of the ground and field layer of the sub-xeric heath forest. secondly, winter feeding results in increased n content in the dwarf shrubs vaccinium myrtillus and empetrum nigrum and in the n content and ph of soil below the humus layer. and thirdly, pellet feeding causes fewer significant effects on vegetation and soil than feeding with grass silage�hay and that grass silage� hay feeding causes fewer effects on plots where uneaten forage was cleared, when compared to uncleared plots. we were also interested in determining when the overall impacts of winter feeding on vegetation and soil become visible. the research utilized an extensive controlled field experiment simulating winter feeding of reindeer over two winters (2008�10) in the hammastunturi herding cooperative in finland. the study was planned and conducted in cooperation with the local herders. material and methods study site the experiment was conducted approximately 15 km from the village of kuttura. the village is located in the hammastunturi herding cooperative (688 21?n, 268 50?e), one of 13 sami reindeer herding cooperatives in northern finland (fig. 1). the area is characterized by boreal coniferous forests, sub-arctic mountain birch woodlands, mires and fells (oksanen & virtanen 1995). the 35 ha site was selected for this study in cooperation with the local herders. it has a ‘‘cold, snowy, forest climate’’ (köppen climate type: dfc) that is characterized by high annual variability. the mean annual temperature, measured from 1970 to 2000, was �0.618c, with a mean temperature in july of 14.18c and in january of �13.08c. annual precipitation was 426 mm; about half of this is snow, which accumulates to a depth of 65 cm and melts on average by 17 may (data obtained from the finnish meteorological institute). the largest permissible number of reindeer in the cooperative is 5500 animals. there are 2.5 reindeer/ km 2 . winter pastures in hammastunturi contain 12.2 ha impacts of winter feeding of reindeer on vegetation and soil m. turunen et al. 2 (page number not for citation purpose) citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 of terricolous lichen pasture/reindeer and 16.0 ha of arboreal lichen pasture/reindeer. some of the forests in the cooperative are protected, and some are used for commercial forestry. the total coverage of infrastructure is 0.8% (17 km 2 ), and its impact area is 6.7% (146 km 2 ) of the land area of the cooperative (kumpula et al. 2009). since the middle of the 1960s, the calving percentage (number of calves born per 100 females as calculated during the summer or autumn calf markings) has ranged between 6 and 75%. it reached its minimum in 1973 (6%) and 1974 (18%) due to a sharp decline in the availability of winter forage, caused by difficult snow conditions. in the 2000s, the calving percentage ranged between 44 and 60% (reindeer herders’ association 2011; vuojala-magga et al. 2011). winter herding in hammastunturi entails herding and feeding in the field or in calving fences. hay, grass silage or pellets are used as feed in winter principally for moving reindeer from one place to another and keeping the herd together. calving fences, which facilitate safe calving, are used from march/april to the end of may, depending on the annual snow conditions. herders began using the fences in the mid-1990s because many calves were born on snow or in water holes due to late snowmelt in the spring. in fence calving, female reindeer are collected and kept in large fenced forest areas, which allows herders to ensure that the animals are fit and well. towards the end of the 2000s, snow began melting earlier and some of the siidas (extended family or kin group consisting of economically independent households) have changed from the calving fence system to the spring herding system, in which reindeer are fed in the forest if snow is deep or hard (vuojala-magga et al. 2011). feeding experiment the feeding experiment, which simulated supplementary winter feeding of reindeer, was conducted from 2 march to 19 april 2009 (49 days) and from 1 march to 30 april 2010 (61 days). the experimental site (35 ha) is a poorly regenerated pine-dominated sub-xeric heath forest (empetrum�myrtillus type [emt]), with scots pine seed trees left after cuttings in the 1950�1960s. it is a typical forestry and winter pasture area in the region. the criteria for selecting the site were that it had to provide easy access by snowmobile for herders in winter for daily feeding and by car for researchers in summer for conducting the field measurements and sampling. in june 2008, 50 experimental plots (ø 5 m, 19.6 m 2 ) were established on the experimental site (35 ha), and each plot was allocated randomly for one of the following feeding practices: (1) feeding with grass silage�hay with leftovers cleared from the plot in the spring; (2) feeding with grass silage�hay with leftovers not cleared; and (3) feeding with pellets. the experiment also included (4) unfenced and (5) fenced control plots, on which the reindeer were not given supplementary forage. the fences were approximately 2 m high and made of wire mesh. reindeer had no access to the fenced plots. each feeding practice was replicated 10 times (total number of plots: 50). the plots were arranged to form an oval; the distance between the closest plots was 30 m and 1 km between the farthest. fig. 1 location of the reindeer winter feeding experiment in the hammastunturi herding cooperative (circle) and of the weather station in saariselkä (star). in the upper map, the reindeer herding area in finland is indicated in black. m. turunen et al. impacts of winter feeding of reindeer on vegetation and soil citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 our approach was practical rather than theoretical, which is why no fenced plots with pellets or grass silage�hay were included in the experiment (reindeer herders fed the reindeer during the experiment). as all of the feeding practices in the experiment (except fenced and unfenced control plots) encompassed not only the impact of forage (grass silage�hay, pellets), but also the effect of reindeer on the pastures in the form of grazing, trampling, digging and droppings, we studied the overall effect of winter feeding on various vegetation and soil variables. another reason for this approach was our expectation that the effects of reindeer on pasture would not be equal in the case of all of the feeding practices. for example, the attractiveness of different types of forage to reindeer varies, with the animals preferring pellets to grass silage�hay. the forage used in the experiment was a mixture of grass silage preserved with molasses syrup and hay (hereafter ‘‘grass silage�hay’’); it was produced 50�100 km from the site. the main forage species were festuca pratensis hudson, deschampsia cespitosa (l.) beauv., phleum pratense l. and taraxacum officinale. the forage also contained trifolium repens l., rumex acetosella l., ranunculus acris l., stellaria media (l.) vill., raphanus raphanistrum l., achillea millefolium l., rumex acetosa l., veronica chamaedrys l. and epilobium angustifolium l. the herders gave reindeer roughly 3 kg of forage/plot/day, which equals 150 g forage/m 2 /day. the animals were also fed with commercial reindeer pellets (tähti-poro artic and tähti-poro 2 balans, kinnusen mylly ltd., utajärvi, finland), which contained oat, wheat, barley and molasses. the herders gave reindeer roughly 1 kg of pellets/ plot/day, which equals 50 g pellets/m 2 /day. the results of the forage and pellet analyses are presented in table 1. according to the reindeer herders participating in this study, the reindeer dug approximately half of their daily forage from the natural pasture. there were between 100 and 200 reindeer at the experimental site and an additional 150 animals in the surroundings. there was no need to fence the site because the reindeer stayed there to feed. the herders fed the animals daily with grass silage�hay and pellets on the clean snow of the plots, transporting the forage by snowmobile on a track made for that purpose. the reindeer in the surroundings were also fed. herders distributed about one-third of the supplementary forage (grass silage�hay and pellets) to the plots and spread the remaining two-thirds in the area between the plots and in the surroundings of the experimental site. accordingly, all reindeer*a maximum of 300 animals* received supplemental forage. on 15 june 2009 and on 26 may 2010, the leftover grass silage�hay, containing mostly dry straw, was removed using a rake from 10 of the 20 plots on which the herders had fed reindeer with grass silage�hay). measurements vegetation surveys. vegetation surveys were conducted before the experiment was established (1�13 july 2008) and after the first (8�20 july 2009) and second (4�12 july 2010) winters. the surveys were conducted on two subplots (1 m 2 ) per plot (altogether 2 �50 plots � 100 subplots) using a point-counting method (molau & table 1 the results of the analysis of grass silage produced in summer 2008 and 2009 and pellets used in the reindeer feeding experiment. the analysis was carried out by viljavuuspalvelu ltd. (mikkeli, finland). parameter grass silage 2008 grass silage 2009 tähti-poro artic pellets tähti-poro 2 balans pellets dry weight (%) 20.4 24.8 87.0 87.2 crude protein (%) a 14.5 16.2 11.4 11.5 raw fibre (%) 31.2 25.7 11.3 10.8 ca (p/kg) a 5.5 4.6 13 12 p g/kga 3.1 2.8 4.0 4.4 mg g/kg a 2.7 3.0 3.9 3.8 k g/kga 18 29 8.8 8.6 na g/kg 0.21 0.21 1.8 2.6 cu mg/kga 8.1 5.3 21 19 mn mg/kg 76 86 zn mg/kga 33 34 110 120 fe mg/kg 88 63 170 190 total content of bacteria cfu/g 530 000 2100 b1000 ca/p 1.8 1.7 0.2 0.2 yeast content cfu/g 77000 b100 b100 ph 3.9 sugar % 8.4 a analysis in accordance with finnish accreditation service standard iso/iec 17025. impacts of winter feeding of reindeer on vegetation and soil m. turunen et al. 4 (page number not for citation purpose) citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 molgaard 1996). in addition to determining the coverage of vascular plants, lichens, mosses and hepatics, the survey recorded coverage of reindeer faeces (see, e.g., campbell et al. 2004; skarin 2007; moen et al. 2009), uneaten forage and bare soil. in addition, the heights of dwarf shrubs and deschampsia flexuosa were measured. to avoid pseudoreplication, mean values for each plot were calculated on the basis of the respective subplots. plant and soil analysis. since the chemical composition of plants was expected to reflect eutrophication caused by experimental reindeer feeding before any changes in soil and species coverage, the evergreen dwarf shrub e. nigrum l. (current-year shoots) and the deciduous v. myrtillus l. (current leaves) were chosen as indicator species. samples were collected from the 50 plots on 25 july 2008, 21 july 2009 and 23 july 2010 for the measurement of c, h and n content (leco-1000, leco corporation, st. joseph, mi, usa). the measurements were conducted from dry ash samples using a thermal gravimetric analyser with inductively coupled plasma emission spectrometry (tja iris advantage, thermo jarrell ash corporation, franklin, ma, usa). soil samples for the measurement of ph and c, h and n content were taken from below the humus layer on each experimental plot; ph was measured in the field (model testo 206, lenzkirch, germany). soil samples were dried at 408c, pre-treated with a 2 mm sieve, and analysed for c, h and n content (% dry weight) using the leco-1000 instrument. statistical analysis we used an analysis of covariance to analyse the effect of reindeer winter feeding on the n concentration and c/n of e. nigrum and v. myrtillus, the coverage (%) of species in the ground and field layer, as well as the ph, n content and c/n of the soil. the data from 2009 (after the first winter) and 2010 (after the second winter) were analysed separately, because we were interested in finding out when the overall impacts of winter feeding on vegetation and soil first become visible. the explanatory variables used in the yearly model were feeding practice (five levels) and the starting values from 2008 (before the experiment was established), the latter being used as a covariate. in addition, we studied the relationship between the coverage of faeces and the coverage and height of d. flexuosa by adding the coverage of faeces into the model and examining only grazed plots (four feeding practice levels). there was no need to make transformations for the response variables, because the diagnostic residual plots were checked and found to be satisfactory. the tests of the effects of feeding practice and year 2008 (covariate) are presented in tables for 2010 only. the multiple comparisons of the covariate-adjusted feeding practice means were analysed using the tukey� kramer method (overall significance level: p �0.05). the feeding practice means in 2008 and the covariateadjusted means in 2009 and 2010 (with the multiple comparisons) are presented in the figures for the species whose coverage in 2010 exceeded 5%. the mixed procedure of the sas statistical software package (version 9.2) was used in the modelling analyses. results reindeer activity and leftover forage mean coverage of faeces, which indicates reindeer activity on the plots, was higher after the first winter (2009) than after the second (2010; fig. 2a). after both years, the mean coverage of faeces was highest on the plots where reindeer were fed with pellets (9% in 2009 and 5% in 2010), ranging between 2 and 5% for other feeding practices. there were no faeces on the fenced control plots. the uneaten grass silage�hay on the plots mainly contained straw. the mean coverage of leftovers on uncleared plots was 26% after the first year (2009) and 29% after the second year (2010) as against 5% and 7% on the cleared plots, respectively (fig. 2b). there were no leftovers on control plots. vegetation surveys in 2008, before any feeding practices were introduced, the field layer of the pine-dominated sub-xeric heath forest site was characterized by evergreen dwarf shrubs (61%), deciduous dwarf shrubs (14%) and graminoids (14%). the most common evergreen shrub species were e. nigrum (39%), calluna vulgaris (16%) and vaccinium vitis-idaea l. (6%) and the most common deciduous shrub was v. myrtillus l. (14%; fig. 3a�d). other shrubs, among them v. uliginosum l., ledum palustre l., diphasiastrum complanatum (l.) holub. and lycopodium clavatum l. were rare (b1%). the only graminoid was d. flexuosa (14%; fig. 3e). the mean percentage of the site covered by non-vegetated bare soil and litter was 9%. the ground layer exhibited mosses (73%), lichens (21%) and bare soil (6%; fig. 3f�i). the most common moss and hepatic species were pleurozium schreberi (34%), dicranum spp. (26%), barbilophozia spp. (7%), hylocomium splendens m. turunen et al. impacts of winter feeding of reindeer on vegetation and soil citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 (5%) and polytrichum spp. (b1%). of the lichens present, the most common species was cladonia rangifera (6%), a type of winter forage preferred by reindeer. no invasive plant species introduced through grass silage�hay could be observed on the plots after two winters of simulated feeding. the overall effect of feeding, including the effect of forage as well as reindeer on the pasture, did not result in significant differences in the mean coverage of dwarf shrub species after the first winter (2009; fig. 3a�d). after the second winter (2010), however, there were significant differences between the feeding practices in the mean coverage of the dwarf shrubs e. nigrum, c. vulgaris and v. vitis-idaea. the coverage was lower or tended to be lower on plots where reindeer were fed with grass silage�hay (leftovers not cleared) compared to the control plots (fig. 3a, b, d, table 2). in contrast, there was a significant effect of feeding practice on the coverage of the graminoid d. flexuosa after the first winter, in 2009 (feeding practice: f �3.09, p �0.025; fig. 3e): its coverage increased on plots where reindeer were fed with grass silage�hay (cleared) when compared to fenced controls. after the second winter (2010), the height of d. flexuosa increased significantly on these plots regardless of whether leftovers were cleared when compared to fenced or not fenced controls (feeding practice: f �8.33, pb0.0001; data not shown in the figures). the models, in which both the starting values from 2008 and the feeding practices were taken into consideration, indicated that there was a significant positive linear relationship on herded plots (fenced control plots excluded) between the coverage of faeces and the coverage and height of d. flexuosa. in 2009, the regression coefficient of the model for coverage of d. flexuosa was 0.32 (p �0.030) and for height 0.55 (p �0.032). in 2010, the corresponding regression coefficients were increased to 0.59 (p �0.021) and 0.96 (p �0.039), respectively. there was a significant effect of feeding practice on the coverage of low-growing mosses and hepatics from the first winter, in 2009 (f �10.96, pb0.0001) onwards (fig. 3f�h, table 2), because leftover forage covered them to a considerable extent. for example, the mean coverage of dicranum spp. after the second winter (2010) was 28% on cleared grass silage�hay plots, but only 15% on uncleared ones (fig. 3h, table 2). there were no significant differences in coverage of lichens between the feeding practices after the first year (2009). after the second year (2010), however, the uncleared plots where reindeer were fed with grass silage�hay or pellets had a significantly lower coverage of lichens when compared to unfenced control plots (fig. 3i, table 2). plant and soil analysis after the first winter (2009), there was a significant effect in n content of e. nigrum due to feeding practices (f �4.68, p �0.003). the mean n content of e. nigrum was 7�9% (fig. 4a), and the c/n ratio was 8�9% higher on the plots with grass silage�hay feeding (leftovers not cleared) compared to control plots (fenced/unfenced). after the second winter (2010), the differences due to feeding practices were more pronounced: the mean n content of e. nigrum was 11�14% higher on uncleared plots and 9�13% higher on cleared plots vs. control plots (unfenced/fenced). feeding reindeer with pellets did not fig. 2 the mean (with standard error) coverage (%) of (a) faeces and (b) uneaten grass silage�hay in the feeding experiment after the first winter (2009) and the second (2010), n �10 plots per feeding practice. impacts of winter feeding of reindeer on vegetation and soil m. turunen et al. 6 (page number not for citation purpose) citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 increase the n content of e. nigrum leaves during the experiment (fig. 4a, table 3). there were no significant differences among the feeding practices in the n content of v. myrtillus after the first winter (2009), but after the second winter (2010), the n content of v. myrtillus was 13�15% higher on uncleared grass silage�hay plots and 14�16% higher on pellet plots when compared to controls (unfenced/ fenced); fig. 4b, table 3). no significant effects of feeding practice on ph or on c and n content measured from the soil below the humus layer could be observed during the experiment. the only exception was soil c/n, which exhibited significant effects due to feeding practices after the second winter: the ratio was 27% lower on grass silage�hay plots (leftovers cleared) when compared to fenced control plots (fig. 4c, table 3). discussion no invasive species introduced from the grass silage or hay could be observed on the plots during our 2-year experiment. this most probably shows that the grass silage�hay, whose main components are festuca pratensis deschampsia cespitosa, phleum pratense and taraxacum officinale, was cut before seeding, that the method for producing the silage decreased seed survival or the seeds failed to germinate for some other reason, or that the seedlings had lost their viability due to winter frosts or unsuitable soil. another reason for the lack of invasive fig. 3 the mean (with standard error) coverage (%) of (a) empetrum nigrum, (b) calluna vulgaris, (c) vaccinium myrtillus, (d) vaccinium vitis-idaea and (e) deschampsia flexuosa in the field layer, and (f) all mosses and hepatics, (g) pleurozium schreberi, (h) dicranum sp. and (i) all lichens in the ground layer of a sub-xeric heath forest before the feeding experiment was started (2008), after the first winter (2009) and the second (2010). the figures for 2008 are starting means, and those for 2009 and 2010 covariate-adjusted means (2008 values as a covariate) for feeding practices. the different letters denote differences between the feeding practices at significance level p �0.05, n �10 plots per feeding practice. m. turunen et al. impacts of winter feeding of reindeer on vegetation and soil citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 species might be the rather moderate level of supplementary grass silage/hay feeding (ca. 150 g per m 2 per day) in combination with the short duration of the experiment (110 days in total during two winters in 2009�10). our earlier research on three intensively used reindeer winter feeding pens (1�360 reindeer in 0.1�100 ha pens for 4�10 winters) in northern finland indicates that lichens, mosses and dwarf shrubs become replaced by faster-growing graminoids and herbs; these include nfavouring pioneer species such as epilobium angustifolium and weeds such as stellaria media that are introduced either through reindeer forage (grass silage�hay) or from the surroundings of the winter feeding pens (turunen et al. 2010; turunen & vuojala-magga 2011). the lack of invasive species in the present study may also be due to the resistance of the sub-xeric heath forest to the overall impacts of forage and reindeer; the appearance of invasive species is dependent on the resistance of the habitat type and/or its ability to resist or recover from erosion caused by grazing, trampling and digging. the habitat types that have the weakest resistance include moist mires and xeric heath forests, whereas mesic and sub-xeric heath forests*the site types in the present study*are more resistant (kellomäki & saastamoinen 1975; ukkola 1995). our experiment showed a significant overall impact of winter feeding on the field and ground-layer vegetation of a sub-xeric pine-dominated heath forest in northern finland. since n is the limiting factor of plant growth in nutrient-poor heath forests (vitousek & howarth 1991), both the fast-growing, n-demanding graminoid d. flexuosa and the slow-growing evergreen dwarf shrub e. nigrum and deciduous dwarf shrub v. myrtillus were able to utilize the increased availability of n compounds. in d. flexuosa, this could be observed already after the first winter both as coverage and height increasing with the coverage of reindeer faeces and as increased coverage where grass silage�hay had been used. in e. nigrum, n content increased on grass silage�hay plots (leftover not cleared in the spring) after the first winter, and in v. myrtillus after the second winter. earlier studies have indicated that the impacts of reindeer grazing on vegetation and soil depend greatly on reindeer population density, season of grazing and the type and successional state of the site (väre et al. 1995; väre et al. 1996; suominen & olofsson 2000; moen et al. 2009; stark et al. 2010). in oligotrophic climax-stage cladonia stellaris-rich pine-dominated forests in northern finland, heavy grazing has been found to result in development of the understorey vegetation in two directions: towards first cladonia stage, or towards bryophyte-rich sites having mesotrophic features such as elevated soil n content and ph (väre et al. 1995; väre et al. 1996). the studies of heathlands and tundra in northern fennoscandia have shown that reindeer may increase the abundance of graminoids and productivity of vegetation through several mechanisms: favouring plants with high-quality litter (olofsson & oksanen 2002), producing rapidly recycled urine and faeces (van der wal et al. 2004) and increasing soil temperatures (olofsson et al. 2004). in general, moderate grazing has been found to increase diversity on heathlands, whereas diversity has remained unaltered or slightly lower on moderately grazed grassand herb-dominated meadows (suominen & olofsson 2000). our results show that both reindeer droppings (faeces and urine) and uneaten forage left on the pasture contributed to the increased availability of n compounds in the sub-xeric forest studied. reindeer faeces and urine provide highly decomposable resources that are rich in labile nutrients, such as ammonium and nitrate, and can stimulate soil microbial biomass and activity, net c and n table 2 f-tests of the effects of feeding practice (10 plots per feeding practice) and the year 2008 (data measured before the experiment was established) on the species coverage in the ground and field layer of the sub-xeric heath type forest after two winters of experimental feeding of reindeer in 2010. feeding practice 2008 (covariate) f significance f significance field layer empetrum nigrum 5.26 0.002 199.90 b0.0001 calluna vulgaris 5.63 0.001 1510.28 b0.0001 vaccinium myrtillus 1.20 0.323 108.96 b0.0001 v. vitis-idaea 2.36 0.068 4.63 0.037 deschampsia flexuosa 8.70 b0.0001 142.24 b0.0001 ground layer mosses and hepatics 9.03 b0.0001 20.57 b0.0001 pleurozium schreberi 3.45 0.016 211.84 b0.0001 dicranum sp. 5.44 0.001 123.15 b0.0001 lichens 3.75 0.010 39.02 b0.0001 impacts of winter feeding of reindeer on vegetation and soil m. turunen et al. 8 (page number not for citation purpose) citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 mineralization, as well as plant n acquisition and growth (suominen & olofsson 2000; stark et al. 2003; van der wal et al. 2004). the origin of the n compounds derived from the uneaten leftover forage may be natural, that is, a species of forage plant, or artificial, for example, fertilizers, preservatives and/or additives used during the production of grass silage. proteolysis (breakdown of proteins) in the grass silage causes ammonium-n to be formed, the content of which increases particularly when the sugar content of grass silage is low (mcdonald et al. 1991; aagnes & mathiesen 1995; heiskari & nieminen 2004). the n compounds, particularly ammonium-n, may thus have been absorbed by the vegetation and soil (or adsorbed onto them) under the forage leftover, leading to increased tissue n content in e. nigrum and v. myrtillus leaves. the release of nutrients from reindeer faeces and uneaten forage left on the pasture is greatly dependent on soil moisture (see, e.g., van der wal et al. 2004), most probably being greatest immediately after snowmelt (17 may in the ivalo*kuttura area in an average year (data obtained from the finnish meteorological institute) and after persistent rains. of the feeding practices applied, feeding with grass silage�hay (leftover not cleared in the spring) most often caused the earliest and most significant overall impacts on vegetation. the low-growing lichens and mosses, such as dicranum spp., and dwarf shrubs observed in this study are easily covered by reindeer forage leftovers on pasture. besides being an additional n source, uneaten forage left in thick layers on pasture may directly decrease photosynthesis and thus suppress the growth of groundand field-layer vegetation. in the spring, a thick layer of uneaten forage with a high straw content may insulate the soil from heat and lead to later melting of soil frost and lower soil temperatures (see peth & horn 2006). conversely, forage leftovers may even out the temperature variation of the soil and slow evaporation from the underlying soil and the vegetation, thereby inhibiting the exchange of other gases also. the present study shows that the overall impact of feeding reindeer with pellets on vegetation and soil below the humus layer was less significant than that caused by feeding with grass silage�hay. on the plots where reindeer were fed with pellets, the species coverage of dwarf shrubs and mosses and hepatics remained unchanged, and n contents in e. nigrum leaves were lower than on the plots where reindeer were fed with grass silage�hay. reindeer prefer pellets to hay or grass silage, and leftovers are not common. therefore, the processing of crude hay*into hay pellets, for example* and/or the use of commercial grain-based reindeer pellets could minimize the amount of leftover foraget a b le 3 f -t e st s o f th e e ff e c ts o f fe e d in g p ra c ti c e (1 0 p lo ts p e r fe e d in g p ra c ti c e ) a n d y e a r 2 0 0 8 (d a ta m e a su re d b e fo re th e e x p e ri m e n t w a s e st a b lis h e d ) o n n c o n c e n tr a ti o n (% ) a n d c /n in e . n ig ru m , v . m y rt ill u s a n d so il, a n d so il p h a ft e r tw o w in te rs o f e x p e ri m e n ta l fe e d in g o f re in d e e r in 2 0 1 0 , a s w e ll a s th e m u lt ip le c o m p a ri so n s (t u k e y �k ra m e r m e th o d ) o f th e c o v a ri a te -a d ju st e d fe e d in g p ra c ti c e m e a n s. f e e d in g p ra c ti c e 2 0 0 8 (c o v a ri a te ) c o v a ri a te -a d ju st e d fe e d in g p ra c ti c e m e a n s (s ta n d a rd e rr o r) 2 0 1 0 f s ig n if ic a n c e f s ig n if ic a n c e c o n tr o l (f e n c e d ) c o n tr o l g ra ss si la g e � h a y , n o t c le a re d g ra ss si la g e � h a y , c le a re d p e lle ts e . n ig ru m n 9 .9 4 b 0 .0 0 0 1 0 .2 9 0 .5 9 1 1 .2 6 (0 .0 3 )a 1 .3 1 (0 .0 3 )a 1 .4 7 (0 .0 3 )b 1 .4 4 (0 .0 3 )b 1 .3 6 (0 .0 3 )a b c /n 1 0 .8 4 b 0 .0 0 0 1 0 .4 5 0 .5 0 6 4 3 .9 9 (0 .8 5 )a 4 2 .4 2 (0 .8 5 )a 3 7 .2 8 (0 .8 4 )b c 3 8 .4 (0 .8 4 )b 4 0 .7 6 (0 .8 4 )a b v . m y rt ill u s n 6 .1 4 0 .0 0 0 5 4 .9 6 0 .0 3 1 1 .4 6 (0 .0 5 )a 1 .4 9 (0 .0 4 )a 1 .6 8 (0 .0 4 )b 1 .5 7 (0 .0 4 )a b 1 .7 0 (0 .0 4 )b c /n 6 .9 0 0 .0 0 0 2 7 .8 0 0 .0 0 8 3 6 .1 6 (0 .9 5 )a 3 5 .0 0 (0 .8 3 )a 3 1 .3 4 (0 .8 3 )b 3 3 .4 0 (0 .8 7 )a b 3 0 .7 9 (0 .8 4 )b s o il n 0 .3 8 0 .8 1 8 0 .9 4 0 .3 3 9 0 .0 6 8 (0 .0 1 ) 0 .0 6 4 (0 .0 1 ) 0 .0 7 5 (0 .0 1 ) 0 .0 6 6 (0 .0 1 ) 0 .0 6 9 (0 .0 1 ) c /n 2 .6 9 0 .0 4 4 0 .0 7 0 .7 9 3 2 3 .8 7 (1 .5 0 )a 1 9 .3 4 (1 .5 0 )a b 2 1 .9 0 (1 .5 0 )a b 1 7 .4 0 (1 .5 4 )b 1 9 .6 8 (1 .6 0 )a b p h 1 .0 3 0 .4 0 3 3 .1 8 0 .0 8 2 4 .6 1 (0 .1 0 ) 4 .7 5 (0 .1 0 ) 4 .6 6 (0 .1 0 ) 4 .8 7 (0 .1 0 ) 4 .6 8 (0 .1 0 ) a ,b ,c d if fe re n c e s b e tw e e n th e fe e d in g p ra c ti c e s a t si g n if ic a n c e le v e l p � 0 .0 5 . m. turunen et al. impacts of winter feeding of reindeer on vegetation and soil citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 and thus environmental impacts such as eutrophication of vegetation and soil and the spread of invasive species. our conclusion is that even a rather moderate level of feeding (ca. 150 g of grass silage�hay and 50 g pellets/ m 2 /day for 49 days in 2009 and 61 days in 2010) may cause changes in vegetation and soil that in the longer term can lead to a gradual shift from a nutrient-poor forest (sub-xeric heath forest type) towards a more nutrient-rich type (mesic heath forest type) (see raunio et al. 2008). this would result in a higher coverage of the n-demanding graminoids that naturally grow in the forest, such as d. flexuosa, or of those derived from the supplementary winter forage of reindeer. it is also likely that the coverage of e. angustifolium, a herb that commonly appears in northern fennoscandic pinedominated heath forests after clear-cutting and soil preparation, would increase. finally, it can be speculated that the impact of winter feeding on forest ecosystems will increase in the future due to predicted climate change. for example, in the summer, increased availability of water and nutrients, especially n compounds in the soil, may improve germination of the seeds of invasive species and the survival and growth of their seedlings (walck et al. 2011). some of the seeds introduced in reindeer forage, those of graminoids and weeds, for example, may end up in the soil seed bank, where they may retain their germination capacity for decades and germinate only when conditions*for instance, temperature and water availability*become more favourable. acknowledgements we thank reindeer herders jaana magga, jarmo haataja and mauno magga of the hammastunturi herding cooperative for participating in this study. special thanks are due to forest engineer jouni puoskari at the rovaniemi research unit of the finnish forest research institute, and msc anna hyyryläinen for their technical assistance during the course of this study. we are also grateful to kyösti tikkanen and laura räsänen for assisting in the vegetation surveys in summer 2010. thanks are also due to richard foley for checking the language of the manuscript. this research is part of the reindeer forage and supplementary feeding in changing climate project (2008�10), which was funded by the ministry of agriculture and forestry (development fund of agriculture and forestry; project no. 2941/503/2007), kinnusen mylly ltd. and the arctic centre of the university of lapland. fig. 4 mean (with standard error) n concentration (%) in leaves of (a) empetrum nigrum and (b) vaccinium vitis-idaea, and (c) c/n of soil on the plots in the sub-xeric heath forest before the feeding experiment was started (2008), after the first winter (2009) and after the second (2010). the figures for 2008 are starting means, and those for 2009 and 2010 covariate-adjusted means (2008 values as a covariate) for feeding practices. the different letters denote differences between the feeding practices at significance level p �0.05, n �10 plots per feeding practice. impacts of winter feeding of reindeer on vegetation and soil m. turunen et al. 10 (page number not for citation purpose) citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 references aagnes t.h. & mathiesen s.d. 1995. round baled grass silage as food for reindeer in winter. rangifer 15, 27�35. åhman b. & danell ö. 2006. can supplementary feeding improve productivity in reindeer husbandry? in l. bartoš et al. (eds.): advances in deer biology. deer in a changing world. proceedings of the 6th international deer biology congress: prague, czech republic, 2006. pp. 30�32. prague: research institute of animal production. aschfalk a., josefsen t.d., steingass h., müller w. & goethe r. 2003. crowding and winter emergency feeding as predisposing factors for kerato-conjunctivitis in semi-domesticated reindeer in norway. deutsche tierarztliche wochenschrifte 110, 295�298. callaghan t.v., johansson m., brown r.d., groisman p.y., labba n., radionov v., barry r.g., bulygina o.n., essery r.l.h., frolov d.m., golubev v.n., grenfell t.c., petrushina m.n., razuvaev v.n., robinson d.a., romanov p., shindell d., shmakin a.b., sokratov s.a., warren s. & yang d. 2011. the changing face of arctic snow cover: a synthesis of observed and projected changes. ambio 40, 17�31. campbell d., swanson g.m. & sales j. 2004. comparing the precision and cost effectiveness of faecal pellet group count methods. journal of applied ecology 41, 1185�1196. eloranta e. & nieminen m. 1986. calving of the experimental reindeer herd in kaamanen during 1970�85. rangifer 1 (special issue), 115�121. forbes b.c., bölter m., müller-wille l., hukkinen j., müller f., gunslay n. & konstantinov y. (eds.) 2006. reindeer management in northernmost europe. linking practical and scientific knowledge in social�ecological systems. ecological studies 184. berlin: springer. hansen b.b., aanes r., herfindal i., kohler j. & saether b.-e. 2011. climate, icing, and wild arctic reindeer: past relationships and future prospects. ecology 92, 1917�1923. heiskari u. & nieminen m. 2004. erilaiset nurmirehut porojen talviruokinnassa. (different grass fodders in the winter feeding of reindeer.) kala-ja riistaraportteja 314. helsinki: finnish game and fisheries research institute. helle t. & kojola i. 2008. demographics in an alpine reindeer herd: effects of density and winter weather. ecography 31, 221�230. jernsletten j.l.l. & klokov k. 2002. sustainable reindeer husbandry. tromsø, norway: centre for sami studies, university of tromsø. kellomäki s. & saastamoinen v.l. 1975. trampling tolerance of forest vegetation. acta forestalia fennica 147, 1�22. kumpula j., stark s. & holand ø. 2011. seasonal grazing effects by semi-domesticated reindeer on subarctic mountain birch forests. polar biology 34, 441�453. kumpula j., tanskanen a., colpaert a., anttonen m., törmänen h., siitari j. & siitari s. 2009. poronhoitoalueen pohjoisosan talvilaitumet vuosina 2005�2008*laidunten tilan muutokset 1990*luvun puolivälin jälkeen. (winter pastures in the northern part of the reindeer management area in finland during 2005�2008*changes in the state of pastures after the mid-1990s.) riista-ja kalatalous*tutkimuksia 3. helsinki: finnish game and fisheries research institute. maijala v. & nieminen m. 2001. winter feeding of reindeer* experiences and results from finland. rangifer report 5, 15�16. mattila e. & mikkola k. 2009. poronhoitoalueen eteläja keskiosien talvilaitumet. tila paliskunnissa 2000-luvun alkuvuosina ja eräiden ravintokasvien esiintymisrunsauden muutokset merkkipiireissä 1970-luvulta lähtien. (winter pastures in southern and central parts of the reindeer herding area in finland. state of the herding districts in the beginning of the 2000s and changes in abundancy of some forage plants in reindeer marking districts from 1970s onwards.) metlan työraportteja 115. vantaa: finnish forest research institute. mcdonald p., henderson a.r. & heron s.j.e. 1991. the biochemistry of silage. marlow, uk: chalcombe. moen j. 2008. climate change: effects on the ecological basis of reindeer husbandry in sweden. ambio 37, 304�311. moen j., boogerd c. & skarin a. 2009. variations in mountain vegetation use by reindeer (rangifer tarandus) affects dry heath but not grass heath. journal of vegetation science 20, 805�813. molau u. & mølgaard p. 1996. itex manual. international tundra experiment. copenhagen: danish polar center. nieminen m. 2010. why supplementary feeding in finland? rangifer report 14, 40�41. oksanen a., .åsbakk k., nieminen m., norberg h. & näreaho h. 1997. antibodies against toxoplasma gondii in fennoscandian reindeer*association with the degree of domestication. parasitology international 46, 255�261. oksanen l. & virtanen r. 1995. topographic, altitudinal and regional patterns in continental and suboceanic heath vegetation of northern fennoscandia. acta botanica fennica 153, 1�80. olofsson j., kitti h., rautiainen p., stark s. & oksanen l. 2001. effects of summer grazing by reindeer on composition of vegetation, productivity and nitrogen cycling. ecography 24, 13�24. olofsson j. & oksanen l. 2002. role of litter decomposition for the increased primary production in areas of heavily grazed by reindeer: a litter bag experiment. oikos 96, 507�515. olofsson j. & oksanen l. 2005. effects of reindeer density on vascular plant diversity on north scandinavian mountains. rangifer 25, 5�18. olofsson j., stark s. & oksanen l. 2004. reindeer influence on ecosystem processes in the tundra. oikos 105, 386�396. pajunen a., virtanen r. & roininen h. 2008. the effects of reindeer grazing on the composition and species richness of vegetation in forest-tundra ecotone. polar biology 31, 1233�1244. peth s. & horn r. 2006 consequences of grazing on soil physical and mechanical properties in forest and tundra environments. in b.c. forbes et al. (eds.): reindeer management in northernmost europe. linking practical and scientific knowledge in social�ecological systems. ecological studies 184. pp. 218�291. berlin: springer. m. turunen et al. impacts of winter feeding of reindeer on vegetation and soil citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 putkonen j. & roe g. 2003. rain-on-snow events impact soil temperatures and affect ungulate survival. geophysical research letters 30, article no. 1188. doi: 10.1029/2002gl016 326. raunio a., schulman a., & kontula t. 2008. suomen luontotyyppien uhanalaisuus. osa 2: luontotyyppien kuvaukset. (assessment of threatened habitat types in finland. part 2: habitat type descriptions.) suomen ympäristö 8/2008. luonto. helsinki: finnish environment institute. reindeer herders’ association 2011. annual statistics of reindeer numbers for the period 1965�2011. (see supplementary file for details about this source.) rovaniemi, finland: reindeer herders’ association. säkkinen h., timisjärvi j., eloranta e., heiskari u., nieminen m. & pukka m. 1999. nutrition-induced changes in blood chemical parameters of pregnant reindeer hinds. (rangifer tarandus tarandus.) small ruminant research 32, 211�221. skarin a. 2007. habitat use by semi-domesticated reindeer, estimated with pellet-group counts. rangifer 27, 121�132. solomon s., qin d., manning m., chen z., marquis m., averyt k.b., tignor m. & miller h.l. jr. (eds.) 2007. climate change. the physical science basis: contribution of working group i to the fourth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. stark s., männistö m. & smolander a. 2010. multiple effects of reindeer grazing on the soil processes in nutrient-poor northern boreal forests. soil biology and biochemistry 42, 2068�2077. stark s., tuomi j., strömmer r. & helle t. 2003. non-parallel changes in soil microbial carbon and nitrogen dynamics due to reindeer grazing in northern boreal forests. ecography 26, 51�59. suominen o. & olofsson j. 2000. impacts of semidomesticated reindeer on structure of tundra and forest communities in fennoscandia: a review. annales zoologi fennici 37, 233�249. tømmervik h., bjerke j.w., gaare e., johansen b. & thannheiser d. 2012. rapid recovery of recently overexploited winter grazing pastures for reindeer in northern norway, fungal ecology 5, 3�15. tryland m., josefsen t., oksanen a. & aschfalk a. 2001. contagious ecthyma in norwegian semi-domesticated reindeer (rangifer tarandus tarandus). veterinary record 149, 394�395. turunen m., oksanen p., markkula i., vuojala-magga t., sutinen m.-l., maijala j. & tuomaala r. 2010. vegetation changes in reindeer winter corrals in finnish lapland. rangifer report 14, 110�111. turunen m., soppela p., kinnunen h., sutinen m.-l.& & martz f. 2009. does climate change influence the availability and quality of reindeer forage plants? a review. polar biology 32, 813�832. turunen m. & vuojala-magga t. 2011. poron ravinto ja lisäruokinta muuttuvassa ilmastossa. (reindeer forage and supplementary feeding in a changing climate.) arktisen keskuksen tiedotteita 56. rovaniemi, finland: arctic centre, university of lapland. tyler n.j.c., turi j.m., sundset m.a., stom bull k., sara m.n., reinert e., oskal n., nellemann c., mccarthy j.j., mathiesen s.d., martello m.l., magga o.h., hovelsrud g.k., hanssen-bauer i., eira n.i., eira i.m.g. & corell r.w. 2007. saami reindeer pastoralism under climate change: applying a generalized framework for vulnerability studies to a sub-arctic social-ecological system. global environmental change 17, 191�206. ukkola r. 1995. trampling tolerance of plants and ground cover in finnish lapland, with an example from the pyhätunturi national park. zeszyty naukowe uniwersytetu jagiellonskiego 98, 91�110. van der wal r., bardgett r.d., harrison k.a. & stien a. 2004. vertebrate herbivores and ecosystem control: cascading effects of faeces on tundra ecosystems. ecography 27, 242�252. väre h., ohtonen r. & mikkola k. 1996. the effect and extent of heavy grazing by reindeer in oligotrophic pine heaths in northeastern fennoscandia. ecography 19, 245�253. väre h., ohtonen r. & oksanen l. 1995. effects of reindeer grazing on understorey vegetation in dry pinus sylvestris forests. journal of vegetation science 6, 523�530. vitousek p.m. & howarth r.w. 1991. nitrogen limitation on land and in the sea: how can it occur? biogeochemistry 13, 87�115. vuojala-magga t., turunen m., ryyppö t. & tennberg m. 2011. resonance strategies of sami reindeer herders in northernmost finland during climatically extreme years. arctic 64, 227�241. walck j.l., hidayati s.n., dixon k.w., thompson k. & poschlod p. 2011. climate change and plant regeneration from seed. global change biology 17, 2145�2161. weladji r.b. & holand o. 2006. influences of large-scale climatic variability on reindeer population dynamics: implications for reindeer husbandry in norway. climate research 32, 119�127. impacts of winter feeding of reindeer on vegetation and soil m. turunen et al. 12 (page number not for citation purpose) citation: polar research 2013, 32, 18610, http://dx.doi.org/10.3402/polar.v32i0.18610 http://www.polarresearch.net/index.php/polar/article/view/18610 http://dx.doi.org/10.3402/polar.v32i0.18610 << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 30%) /calrgbprofile (none) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /error /compatibilitylevel 1.4 /compressobjects /off /compresspages true /convertimagestoindexed false /passthroughjpegimages true /createjobticket false /defaultrenderingintent /default /detectblends true /detectcurves 0.1000 /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedopentype false /parseiccprofilesincomments true /embedjoboptions true /dscreportinglevel 0 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize false /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preservedicmykvalues true /preserveepsinfo true /preserveflatness true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /remove /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /cropcolorimages true /colorimageminresolution 150 /colorimageminresolutionpolicy /ok /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagemindownsampledepth 1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages false /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /cropgrayimages true /grayimageminresolution 150 /grayimageminresolutionpolicy /ok /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagemindownsampledepth 2 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages false /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.40 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /cropmonoimages true /monoimageminresolution 1200 /monoimageminresolutionpolicy /ok /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /checkcompliance [ /none ] /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly true /pdfxnotrimboxerror false /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox false /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (euroscale coated v2) /pdfxoutputconditionidentifier () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /false /createjdffile false /syntheticboldness 1.000000 /description << /deu <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> /fra <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> /jpn <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> /ptb <feff005500740069006c0069007a006500200065007300740061007300200063006f006e00660069006700750072006100e700f5006500730020007000610072006100200063007200690061007200200064006f00630075006d0065006e0074006f007300200050004400460020006500200065006d0069007400690072002000720065006c0061007400f300720069006f007300200073006f00620072006500200063006f006e0066006f0072006d0069006400610064006500200063006f006d0020006f0020005000440046002f0058002d0033002e0020005000440046002f0058002000e900200075006d0020007000610064007200e3006f002000640061002000490053004f00200070006100720061002000740072006f0063006100200064006500200063006f006e0074006500fa0064006f00200067007200e1006600690063006f002e002000500061007200610020006f00620074006500720020006d00610069007300200069006e0066006f0072006d006100e700f50065007300200073006f00620072006500200063006f006d006f00200063007200690061007200200064006f00630075006d0065006e0074006f0073002000500044004600200065006d00200063006f006e0066006f0072006d0069006400610064006500200063006f006d0020006f0020005000440046002f0058002d0033002c00200063006f006e00730075006c007400650020006f0020004700750069006100200064006f002000550073007500e100720069006f00200064006f0020004100630072006f006200610074002e0020004f007300200064006f00630075006d0065006e0074006f0073002000500044004600200070006f00640065006d0020007300650072002000610062006500720074006f007300200063006f006d0020006f0020004100630072006f006200610074002c002000520065006100640065007200200034002e00300020006500200070006f00730074006500720069006f0072002e> /dan <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> /nld <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> /esp <feff0055007300650020006500730074006100730020006f007000630069006f006e00650073002000700061007200610020007200650061006c0069007a0061007200200075006e00200069006e0066006f0072006d006500200073006f0062007200650020006c006100200063006f006d007000610074006900620069006c006900640061006400200063006f006e0020005000440046002f0058002d003300200079002000670065006e006500720061007200200064006f00630075006d0065006e0074006f007300200050004400460020007300f3006c006f00200073006900200073006f006e00200063006f006d00700061007400690062006c00650073002e0020005000440046002f005800200065007300200075006e002000650073007400e1006e006400610072002000490053004f0020007000610072006100200065006c00200069006e00740065007200630061006d00620069006f00200064006500200063006f006e00740065006e00690064006f00200067007200e1006600690063006f002e002000500061007200610020006f006200740065006e006500720020006d00e1007300200069006e0066006f0072006d00610063006900f3006e00200061006300650072006300610020006400650020006300f3006d006f00200063007200650061007200200064006f00630075006d0065006e0074006f0073002000500044004600200063006f006d00700061007400690062006c0065007300200063006f006e0020005000440046002f0058002d0033002c00200063006f006e00730075006c007400650020006c006100200047007500ed0061002000640065006c0020007500730075006100720069006f0020006400650020004100630072006f006200610074002e0020004c006f007300200064006f00630075006d0065006e0074006f00730020005000440046002000730065002000700075006500640065006e00200061006200720069007200200063006f006e0020004100630072006f00620061007400200079002000520065006100640065007200200034002e003000200079002000760065007200730069006f006e0065007300200070006f00730074006500720069006f007200650073002e> /suo <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> /ita <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> /nor <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> /sve <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> /enu (settings for the rampage workflow.) >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice reindeer husbandry/hunting in russia in the past, present and future leonid m. baskin the dynamic state of reindeer husbandry in northern russia during the 20th century was studied as a basis for predicting the consequences of the current drastic changes taking place there. similar forms and methods of reindeer husbandry were used with different frequencies and effectiveness throughout the century. in the future reindeer husbandry will conform to market requirements, landscape features and national traditions. in some areas, the more sophisticated methods of management developed in conjunction with large-scale, highly productive reindeer husbandry, could be lost and a subsistence economy, including hunting, could predominate. l. m . baskin, institute of ecology and evolution, 33 leninsky prospect, moscow 11 7071, russia. since 1991, in the russian north, social and economic reconstruction of the rural economy has had a strong impact upon reindeer husbandry. by the 1980s, in northern russia, reindeer husbandry was highly productive (2.3 million domestic reindeer produced for consumption; 4 1.9 thousand tonnes live weight). a steep decline occurred in the 1990s, and at present in russia there are ca. 1.6 million domestic reindeer. in chukotka (see fig. i ) their numbers declined from 500000 to 130oog, and large declines were observed in evenkiya, yakutiya and kamchatka. only in yamal has significant growth of the reindeer population taken place in response to market requirements from the gas and oil industry development (khmshchev & klokov 1998). these events are important for the human population of northern russia (about 12 million) of which about 130000 belong to minorities who are closely connected with exploitation of reindeer as an important food and fur resource. this paper’s aim is to evaluate the ecological and social consequences of ongoing changes in reindeer husbandry. i take as a starting point for my predictions the study of reindeer husbandry devel opment during the last century. it i s observed that khanty-mansiiski! okrug t&a ivenkiya biryatiya khabarovskii kray fig. 1. localities mentioned in the paper; settlements are marked 0 baslun 2000: polar research 19(1), 23-29 23 the same principal features have occurred in different times and areas (baskin 1991). the drastic changes occumng in reindeer husbandry in recent years will probably lead to situations that have occurred in the past. in addition, i point out that the reindeer is one of the few species whose domes tication could occur without taming and while the species is also being hunted (baskin 1974; hudson 1989). all types of reindeer hunting and husbandry can be practised along a “procurement-production” gradient (hudson 1989). sophisticated methods of hunting, when humans used knowledge of migra tory routes as well as directing reindeer herds to stone traps or to human settlements (spiess 1979; skogland 1989), were the first stages of husbandry. control of reindeer in husbandry is based on aboriginal peoples’ traditional knowledge of pas tures, reinforcing herding behaviour and regulation of feeding. i suggest that any future changes in the human-reindeer relationship, even the replacement of husbandry by hunting, will remain on the same procurement-production gradient and will use the same methods of management. the main advantage of reindeer husbandry, in comparison with hunting, is the possibility it provides for harvest at any moment; to have a guarantee of labour and survival. history gives us plenty of tragic examples of famine and extinction of hunting indigenous peoples, but prosperity of people who have husbanded reindeer (vdovin 1965; gurvich 1982). for northern eurasia, fluctuations of wild reindeer numbers have a periodicity of 115-130 years (krupnik 1975). now, when the possibility of a complete crash of reindeer husbandry exists, we need to consider whether is it theoretically possible to exchange husbandry with hunting of wild or feral reindeer. by the 1930-40s, political reforms were in stituted to establish large-scale, maximum produc tion husbandry under the management of state bureaucrats. to attain high productivity, the experience of native herders, as well as scientific knowledge, were used. in this paper, i shall review the most important methods of reindeer husbandry intensification and consider their prospects. comparing features of reindeer husbandry in different areas and periods the main social event in reindeer husbandry in the 1930-40s was the alteration of property rights. state managers followed communist doctrine, which aspired to eliminate rich owners, to unite small owners, and to arrange for maximum state control. large properties were expropriated (sometimes purchased) and incorporated into state farms. small-scale owners were united into cooperative farms (kolkhoz), which were also under the supervision of state authorities. on many occasions the same individuals, families or groups of families became the staff of new state or kolkhoz farms, and therefore managed the same animals which had been their property only a year before. currently we observe the opposite process in the privatization of herds. herders deprived of state control and subsidies use the animals for their own needs. in soviet times private persons also owned reindeer, which comprised up to 10% of the total number of state and kolkhoz animals. d. khorolia (pers. comm.) suggests that the modem growth of nentsi reindeer husbandry in the yamal and bo1:shezemel’skaya tundra is an example of the rapid development of private properties. throughout the 20th century, different systems of management were used. “close” herding, defined as keeping reindeer in big herds, was the main technique in the tundra and forest-tundra zones of bol’shezemel’skaya tundra, yamal, taymyr, yakutiya, chukotka and kamchatka. the “free-camp’’ system, in which reindeer are kept in the vicinity of human settlements or camps, was used in tofalariya, tuva, buryatiya and sakhalin. “loose” herding, in which herders only periodically gather scattered animals and move them to fresh pastures, was practised on the kola peninsula and in khanty-mansiiskii okrug, yaku tiya and evenkiya. in some areas, two or more methods were used. for example, on the kola peninsula there are two distinct indigenous tradi tions. saami employ loose herding in winter, very strictly control females during the calving season, and release reindeer during the summer period. they gather reindeer in large herds again after the rutting season. komi people use close herding year round. their technology provides better results than the saami method. however, attempts of soviet authorities to force saami to use komi technology were not successful. in a few areas, reindeer are maintained in fenced enclosures (kola peninsula, yakutiya, khabarovskii kray) but the high costs of this method limit its feasibility. keeping reindeer in large herds occurred in all periods but with different frequency. since the 1940s, each state or collective farm (kolkhoz) 24 reindeer husbandryhunting in russia in the past, present and future table 1. variations i n the proportion of herds of different sizes under early development of reindeer husbandry in the soviet union, expressed as percent. total number of animals i n a herd (%) years < 50 51-100 101-300 301-500 501-1000 < 1000 ~~~ ~ yamal 1929 64 15 17 4 0 0 chukotka 1937-38 3 2 24 22 9 7 6 n. kamchatka 1933 66 19 13 1.7 0.3 0 possessed about 7000-20 000 animals divided into herds of 1000-2500 animals. these herds were managed by teams of 5-6 herders and 1-2 cooks (usually wives of herders) which received a salary from the farms. herds were rotated along seasonal routes which were determined by pasture utiliza tion plans developed for each farm. before the 193os, in tundra areas there wefe a few large family-owned herds, with a maximum of up to 8000 animals (table 1). isaev (1935), anonymous (1939), shmit (1939) and ustinov (1956) pointed out that small herds were not able to roam independently and thus their owners united to have at least a hundred animals in each herd. behavioural research (baskin 1974) demon strated that the minimum herd size available for human management is 35. for herding, the optimal size is 100-300 animals, whereas the maximum herd size is 1500-3000 animals (excluding new borns) because larger herds become fragmented. prior to the socialist reconstruction, regular and fairly remote routes of migration were typical only for the herds of rich owners (isaev 1935; razdelishin 1938, 1940). those routes usually remained unchanged and were later used by state and kolkhoz farms. small-scale owners occupied inland areas and moved more or less chaotically, often staying more inside certain restricted areas than following planned routes. migratory routes often depended on involvement of herders in other activities (harvesting marine animals, fishing, hunting, transporting loads). for example, all inhabitants of the vast treeless areas of taymyr (nganasans, dolgans, nentsi) in the past, as well as nowadays, adjust their routes in late autumn to the forest line in order to collect firewood for heating. inhabitants of coastal areas moved from the sea not further than 40-60km (in winter) in order to be back near the sea in early summer when the sea mammal hunting season begins (kopylov 1932; anonymous 1945). these short “circles” of migration were mostly conserved in soviet times, when reindeer herds inhabiting coastal zones were the property of kolkhozes whose main activities were fishing and sea mammal harvesting. herd size, animal distribution within pastures, speed of pasture rotation and methods which herders use to keep animals under control all strongly depend on landscape features, e.g. whether it is forest or tundra zone, narrow pasture (along canyons) or broad pasture (in flat, mon otonous tundra) (baskin 1970). growth of productivity organizers of socialist reindeer husbandry aspired to develop highly productive husbandry. to my knowledge, there was a shortage of scientific knowledge of reindeer husbandry at that time. however, the organizers of the state and kolkhoz farms made extensive use of indigenous knowl edge. they made estimations of the carrying capacity of pastures and used these data to plan the growth of domestic reindeer numbers (ivanov 1941; razdelishin 1938, 1940). they observed that significant portions of small herds were sledge and riding reindeer and that even some females were used for transport. production derived from small herds was either used by the owners or sold in rural markets. only the large herds of rich people provided significant commodity produc tion. the policy of increasingly large herds was accepted by the organizers of reforms. organizers also determined that productivity is dependent on the proportion of females in a population. a high level of barrenness was found to be connected with biased male/female ratios (table 2 ) . according to the state standard later accepted in the ussr, the herd sex ratio must be one 3-year-old bull per 18 females and one 24-year-old bull per 20 females (1 : 18 on average) (borozdin et al. 1977). dividing herds before calving season into female and male portions, which was in the past done only by rich owners, had also become a baskin 2000: polar research 19(1), 23-29 25 table 2 . characteristics of reindeer husbandry in the russian north in 1935 ~~ % of % of bulls % of area, locality groups population per holding 22-years breeding bulls native total human reindeer females used in castrated taiga zone evenkiya: kureyka river magadan: sea of okhotsk shore tundra zone taymyr: mouth of enisey river us’ avam chukotka: markovo kety, evenks, 140 13 30 2.8 23 sel’kupy evens 2154 26-58 40 3.6 32 nentsi, 2 6 4 3 yuraki, 2627 19-124 3 1 4 0 * dolgane, evenki nganasans 450 117 * * i chukchi, 117 4 6 7 7 1.5-5.5 22 evens * *no data. routine obligatory activity in all state and kolkhoz farms. in the reindeer husbandry of chukotka and kamchatka, managing herds with the assistance of dogs became a common practice. in the past, herders of these areas had not used reindeer dogs. plenty of these useful helpers were transported from the nentsi region to the eastern regions. among other innovations introduced in soviet times were salt supplies for reindeer, permanent and transportable corrals, radio communication, provision of food and other necessities to the herders by airplanes, helicopters or tractors, and field huts equipped with iron stoves and some times synthztic covers. as a result, reindeer farms attained high productivity (table 3). the future i predict two possible future scenarios. 1) the more optimistic one predicts preservation of the modern situation when a number of large farms established under the former ussr were supple mented by a number of small farms. the total number of reindeer, should this system prevail, will be stabilized at the level of local requirements for meat and skins, and ownership of animals will be partly changed because of the conversion of state farms into either cooperative farms or private herds. 2) the more pessimistic scenario predicts that productive reindeer husbandry will be pre served only in areas with optimal conditions for large herd husbandry and with more developed cultures of reindeer management (nenetskii okrug and yamal, yakutiya, chukotka, kamchatka). however, in the taiga zone and in areas with high numbers of wild reindeer, domestic reindeer herds will be preserved only in some localities where they will serve more as sources of transport reindeer than of meat and skins. some families table 3. maximum survival, calf production and meat production achieved at selected state reindeer farms of the russian north. ~ _ _ _ _ animals survival calves per 100 meat production area year rate (76) females (i00 kg per 100 animals) nenetskii 1949 93 82 evenkiya 1944 84-90 67-68 14.3 chukotka 1989 89 67 19.7 kamchatka 1960 99 93 32.0 * yamal 1962 92 67 5.4 yakutiya 1975 91 69 22 *no data. 26 ~~ reindeer h u s b a n d r y h u n t i n g in russia i n t h e past, p r e s e n t a n d future will preserve domestic reindeer in localities where the successful hunting of wild reindeer is not guaranteed. the experience of the drastic growth of the reindeer population of yamal provides evidence of the significant influence of gas and oil develop ment. there, the strong market for meat coupled with significant financial assistance resulted in peak productivity prior to the collapse of subsidies. unfortunately, overgrazing of the pastures of yamal occurs now as a result of chaotic reindeer husbandry development (m. okotetto, pers. comm.). even highly productive farms need subsidies from the state. in soviet times the state deliber ately paid significant additional sums for the produced meat so that income was sufficient to cover the expenses of salary, transport, commu nication, field tents and cloth. the same situation exists today in some regions. for example, in his 1996 decree the chukotka governor, a. nazarov, presented significant subsidies for all meat pro duced by reindeer farms (nazarov 1996). accord ing to the calculations of khokhlenkov (1998), in chukotka the cost of 1 kg of produced meat is 8 usd but the market cost is only 2.5 dollars. expenses for venison production include 12% for salary, 6% for transport and fuel, and 21% for corrals and field huts. the cost of dead and lost animals is 61% of total expenses. the latter expense was, in soviet times, three times less. maintenance of more complicated, highly productive methods of herding and hunting requires increased investments and labour, more sophisticated management and highly qualified herders, and better personal discipline among herders. as an example, a delay of only one week in the departure of a reindeer herd from winter grounds towards calving grounds will be followed by a chain of unfortunate events: the herd will not be able to cross large rivers on ice; it will a m v e in summer pastures too late, when fresh vegetation will become scarce; the animals will suffer from insect harassment; the development of calves will be delayed, as well as the fattening of adult animals; the chances of hoof disease will increase; lean reindeer will suffer during the following winter; and calving in the next spring will suffer because of lean females will give birth to weak calves. hunting wild reindeer was always an important part of the subsistence economy. the low numbers of wild reindeer in the first part of the 20th century stimulated the development of reindeer husbandry as a more reliable mode of production. before the 1930s, in taymyr, nganasans used domestic reindeer more for transport than as productive animals. they were compelled by soviet autho rities to become more dependent on reindeer husbandry. however, in the 1970s, when the harvest of wild reindeer became the most im portant activity, nganasans willingly returned to their traditional way of life. the same was true of the evenks in evenkiya (anonymous 1945; savel'ev 197 1). in future subsistence economies wild reindeer will occupy a much more important position than in previous times. a decline in the number of domestic reindeer may stimulate the growth of wild reindeer populations on recently freed pastures. the taymyr population of 600 000 wild reindeer and the wrangel island population of 3000 feral reindeer have been harvested since 1993 only on a small scale. however, observations from these areas during 1993-98 have not provided evidence of significant growth of these populations. in northern eurasia w e know of only two examples of reindeer declining as a result of population crashes. this occurred twice with bering island's population of feral reindeer (abolits 1987). another example, more disputable, was given by semenov-tien-shanskiy (1989) for the lapland skii nature reserve. thus, we have few observa tions upon which to predict a catastrophic growth of wild reindeer populations. unique features of particular indigenous herd ing traditions as well as local ecological conditions must be considered to provide a sound prognosis. for some natives (komi, nentsi, yakuts, chukchi, koryaks), commodity reindeer husbandry is tradi tional. for others, such as nganasans, evens and evenks, who are more deeply involved in hunting and fishing, reindeer husbandry is only a sub sidiary activity. yet in soviet times these peoples were compelled to develop commodity reindeer husbandry. in areas inhabited by these natives which experienced a decline in reindeer husband ry, the return of the people to hunting and fishing occurred quickly. among chukchi and koryaks the division between coastal and inland populations is well known. coastal inhabitants showed more inclina tion to harvest sea mammals and fish than to breed reindeer. the same situation existed in soviet times; reindeer husbandry in coastal areas primar ily served the local market for meat and skins. at baskin 2000: polar research 19(1), 23-29 27 present, coastal reindeer husbandry in chukotka has almost completely declined, but inland husbandry has survived. sooner or later the situation of the 1930s may again be repeated: inland husbandry will produce meat and skins for consumption in coastal settlements, receiving in exchange necessary goods. conclusion reindeer is the most important biological resource of the north and the different ways it is exploited will not be abandoned but will undergo major changes. however, dependence on state subsidies can lead to the degradation of traditional indigen ous economies. among the various forms of reindeer exploitation, hunting wild or feral rein deer will remain important for subsistence econo mies and the rural market. in some areas (taymyr, yakutiya) hunting may provide meat and skins for a market provided by fishermen, miners, and military settlements. in the areas where there are few wild reindeer, the existence of such markets will stimulate the conservation of large-scale reindeer husbandry. cultural traditions of the native peoples of northern russia will also contribute to the conservation of reindeer husban dry. the drastic decline of husbandry in some areas may lead to the loss of technology necessary for highly productive husbandry. scientific de scription of the indigenous practices and beliefs associated with reindeer herding, combined with its publication in both technical and general books, will be necessary to preserve indigenous culture for future generations. references abolits, a. s. 1987: istoriya vozniknoveniya i perspectivy eksploatatsii populyatsii severnykh oleney na ostrove bare ntsa. (history of the establishment and perspectives on the exploitation of the reindeer population on barents island.) in v. e. sokolov (ed.): ratsional’noe prirodopol’zovanie nu komandorskikh ‘ostrovakh. (efficient utilization of natural resources in komandorskie islands.) pp. 144-146. moscow: moscow university publ. anonymous 1939: ekonomicheskiy ocherk basseyna reki anadyr’ chukotskogo natsional’nogo okruga. (economic overview of the anadyr’ river basin in chukotka national okrug.) central state archive, fond a-310, opis’ 18, delo 332. anonymous 1945: materialy pervonachal’nogo zemleus troystva avamskogo rayona taymyrskogo okrugu kras noyurskogo kruya za 1934-1935 gody. (data on preliminury lund use organization in avum rayon, taymyr okrug, krasnoyarsk kruy, 1934-1 935.) central state archive, fond a-310, opis’ 18, delo 67. baskin, l. m. 1970: severnyi olen’. ekologiya i povedenie. (reindeer. ecology und behaviour.) moscow: nauka publ. baskin, l. m. 1974: management of ungulate herds in relation to domestication. in v. geist and f. walther (eds.): the hehaviour of ungulates and i t s relation to managemenr. vol. 2. fucn publ., new ser. 24, 530-541. morges, switzerland. int. union for the conservation of nature. baskin, l. 199 i : reindeer husbandry in the soviet union. in l. renecker & j. hudson (eds): wi/dl$e production; conservu tion and sustainable development. pp. 21 8-26. fairbanks: university of alaska. borozdin, e. k., voqtryakov, p. n. & d’yachenko, n. 0. 1977: razvedenie olene). (reindeer breeding.) krasnoyarsk krasnoyarsk publ. gurvich, i. s. 1982: yukagiry. (yukagirs.) in a. p. okladnikov (ed.): etnicheskaya isroriya narcidov severu. (ethnic hisforj of northern peoples). pp. 168-179. moscow: nauka publ. hudson, r. j. 1989: history and technology. in r. j . hudson et al. (eds.): wildlife production systems. economic utilization qf wild ungulates. pp. 11-27. cambridge: cambridge university press. isaev, v . y. 1935. otchet po ohsledovuniyu olenevodstvu i sobukovodstvu nu polyarnoy stantsii mysa shmidta. ( a study of reindeer husbandry and dog breeding in the ureu around the station m y s shmidta.) central state archive, fond a-310, opis’ 18, delo 88. ivanov, p. 1941 : zemleustroistuo rayonov severnogo pober ezh’ya okhotskogo morya za 1935-1940 gody. (land use organization of the northern shores of the sea of okhotsk, 1935-1940.) central state archive, fond a-310, opis’ 18, delo 488. khokhlenkov, v. 1998: okhota na severnogo olenya. (hunting of wild reindeer.) krasnyi sever 4 , 4. khrushchev, s. a. & klokov, k. b. 1998: nenetskoe olenevodstvo: podkhody k razrabotke kontseptsii ustoychi vogo razvitiya (nenetski reindeer huabandry: approaches to developing a concept of sustainable use.) etnogeogruphi cheskie i etnoekologicheskie lssledovaniya 7, 1-47, kopylov, i. p. 1932: ocherk khozyaistvennoy deyatel’nosri tuzemnogo naseleniya dudinskogo rayona. (outline of the economic activiry of the native population of dudinka rayon.) central state archive, fond a-310, opis’ 18, delo 21. krupnik, i. i. 1975: prirodnaya sreda i evolutsiya tundrovogo severnogo olenevodstva. (natural environment and evolution of tundra reindeer husbandry.) in s . a. arutyunov et al. (eds.): karta, .skhema i chislo v etnicheskoy geografii. ( m a p , diagram, and figure in ethnic geography.) pp. 26-43. moscow: moskovskii filial geograficheskogo obshchestva sssr (moscow dept., ussr geographical soc.). nazarov, a. 1996: mery po stabilizatsii ael’skogo khozyaistva chukotskogo autonomnogo okruga v 1966. (steps to stabilize agricultural husbandry in the chukotka autonomous okrug in 1996.) kraynii sever 119, 5 . razdelishin, l. 1938: plan 3 pyatiletki po vostochno-tundro vomu rayonu nu p e r i o d s 1938 goda p o 1942 god. (plan of the thirdfive-year period for eastern tundra rayon from i938 to 1942.) central state archive, fond a-310, opis’ 18, delo 137, pp. 103-153. razdelishin, l. 1940: kratkiy ocherk olenevodstva vostochno 28 reindeer husbandrykunting in russia i n t h e past, p r e s e n t and future tundrovogo rayona chukotskogo okruga dal ’nevostochnogo kraiya. (overview of reindeer husband? of eastern tundra rayon dul’nevosfochnyi krav.) central state archive, fond a-310, opis’ 18, delo 419. savel’ev, d. v. (ed.) 1971: sevemoe olenevodstvo evenkii. (reindeer husbandry of evenkiya.) krasnoyarsk: nauchno issladovatel’skii institut krainego severa (scientific inst. of the extreme north publ.). semenov-tien-shanskiy 0. i. 1989: istoriya severnogo olenya na kol’skom poluostrove (history of wild reindeer on the kola peninsula). in p. 1. danilov (ed.) t e s n o y severnii o h ’ (wild reindeer). pp. 15-8. petrozavodsk: institut biologii. shmit, e. v . 1939: kratkiy ocherk olenevodstva i sobakovodsrva chaunskogo rayona. (short outline of reindeer husbandy and dog breeding in chuunskiy rayon.) central state archive, fond a-3 lo, opis’ 18, delo 33 i . skogland, t. 1989: comparative social organization of wild reindeer in relation to food, mares and predutor avoidance. berlin: paul parey scientific publ. s p i e s , a. e. 1919: reindeer and caribou hunters. an archaeological study. new york: academic press. ustinov, v. 1956: olenevodstvo nu chukotke. (reindeer husbundry ai cliukotku.) magadan: magadan’ publ. vdovin, 1. s. 1965: ocherki isrorii i etnografii chukclzei. (historical and ethnographic overview of chukchi.) moscow: nduka publ. baskin 2000: polar research 19(1), 23-29 29 small airplanes are a rare link with the outside world, village of sosnovka, kola peninsula, july 1996. photo: y. konstantinov. herders operate on a bruised neck, tichka corral bate, kola peninsula, may 1998. reindeer herding cooperative “olene vod”, village of kraanoshchelye. kola peninsula. photo: y. konstantinov. aligning struts during sled construction, kola peninsula. photo: y. konstantinov. aunt zina, village of kmsnoshchelye, kola peninsula, june 1998. photo: y. konstantinov. many new-born calves are trampled in the spring inarking corrals. the pelts are used’ for parka hoods. tundra camp of brigade no. 3 , “tundra” cooperative, kola peninsula. photo: y. konstantinov. konstantinov. sled-building by the river yokanga, kola peninsula. photo: y. 30 por_002.fm 14 polar research 26 (2007) 14 – 21 © 2007 the authors blackwell publishing incmalden, usaporpolar research0800-03952007 blackwell publishing ltd? 20072611421original articles coastal cliff retreat in kongsfjorden, svalbardb. wangensteen et al. measuring coastal cliff retreat in the kongsfjorden area, svalbard, using terrestrial photogrammetry bjørn wangensteen, 1 trond eiken, 1 rune s. ødegård 2 & johan ludvig sollid 1 1 department of geosciences, university of oslo, oslo, norway 2 gjøvik university college, gjøvik, norway abstract as part of the international project arctic coastal dynamics, results from two sites for measuring coastal cliff retreat in the kongsfjorden area in svalbard (79 ° n, 13 ° e) are presented. the two sites were established in august 2002 and revisited in august 2004. photographs with stereo coverage were taken at distances of 7 and 15 m from the cliff walls with a 60-mm hasselblad camera mounted on a theodolite. fixed points were established by drilling bolts into the cliff wall and were then surveyed. these fixed points were used as control points for orientation of the photogrammetric models. digital photogrammetry applied to scanned photographs of the sites resulted in a detailed digital terrain model (dtm) for each site and year. the coastal cliff retreat rates were found by differencing the dtms of 2002 and 2004. as a result of the short distance between camera and cliff, the dtm differencing was accurate down to 10 mm at least. the results show a yearly retreat of 2.7 and 3.1 mm. these rates are taken to be significant as most of the retreat takes place within small areas with rates well above the accuracy limits of the technique. the results are analysed and discussed in light of earlier rock-wall retreat studies in the same area. keywords cliff retreat; coastal retreat; photogrammetry; svalbard. the shorelines of the arctic ocean are about 44 000 km in length according to the world vector shoreline (soluri & woodson 1990). the international project arctic coastal dynamics (acd) aims at assessing the rates and magnitudes of erosion and accumulation of arctic coasts, and to estimate the quantity of sediments derived from coastal erosion (rachold et al. 2005). as part of the acd project, the work presented here contributes by obtaining reference data from relative stable bedrock coastal cliffs in the arctic, which have not been well studied. the investigation sites are in the kongsfjorden area in the western part of the svalbard archipelago (fig. 1). there are very few data available on coastal cliff retreat rates in svalbard. prick (2004) found a rock wall retreat of 1.9 mm y − 1 in a sandstone and shale rock wall in longyearbyen using sediment traps. this used to be a coastal cliff but it was cut-off from the sea by road and harbour constructions some 10 years before the monitoring started. other studies have assessed general rock wall retreat rates in svalbard ranging from 0 to 1.58 mm y − 1 (rapp 1960; andré 1997; berthling 2001). all of these studies are based on estimating the volume of slope deposits and then assessing retreat rates by assuming the time period for which the slope deposits have developed. andré (1997) directly measured rock wall retreat in areas where both stable and retreating rock walls are found using lichonometry as a chronological control. the appearance of the coastal rock walls together with the quantity of angular rock fragments accumulating on the snowand ice-foot below coastal cliffs during spring show that subaerial mechanical weathering is active and important (o. liestøl, pers. comm.). in some areas the snow and ice can survive all the way through summer above the high tide, indicating that the removal of material is restricted to heavy storms recurring in the fjords at intervals of several years (ødegård & sollid 1993). it has been observed that the ice-foot plays an important role in both removal of weathered material from the base of arctic coastal cliffs and fracturing the lower part of cliff walls (nielsen 1979). correspondence bjørn wangensteen, terratec as, p.o. box 513, no-1327 lysaker, norway. email: bjorn.wangensteen@terratec.no doi:10.1111/j.1751-8369.2007.00002.x b. wangensteen et al. coastal cliff retreat in kongsfjorden, svalbard polar research 26 (2007) 14 – 21 © 2007 the authors 15 ice-feet and sea ice protect the coastal cliffs in svalbard fjords from wave energy during most of the year. submerged strandflat areas along most of the outer western coast also reduce the amount of energy reaching the shores (ødegård & sollid 1993). arctic coastal cliffs are subjected to different types of subaerial and marine weathering processes, and frost weathering has been proposed by høgbom (1914) and nansen (1922) to be an important process regarding the formation of the coastal cliffs characteristic of svalbard fjords. nansen also suggested that the strandflat forms because of the interaction of frost weathering and marine processes at the base of the cliffs, with frost weathering as the main fracturing agent and marine processes removing the weathered material. ødegård & sollid (1993) investigated the temperature in a coastal cliff near ny-ålesund on an hourly basis from august 1987 to august 1988. the steep temperature gradients and available water from snow melting are believed to favour water migration in the fractured dolomitic limestone at < 0 ° c temperatures. spring and summer snowmelt periods are therefore favourable for crack expansion and rock fracturing. a similar study was performed in liefdefjorden from may to august 1992 and a similar temperature regime was found (ødegård et al. 1995). it is suggested that permafrost controls the cliff temperature regime in such a way that the conditions in spring and summer, with a melting snow cover providing sufficient moisture, is favourable to rock breakdown. ødegård & sollid (1993) and ødegård et al. (1995) did not perform any direct measurement of crack expansion or retreat rates in their studies. as weathered material is removed from the base of the cliff by wave action and sea ice in coastal settings, it is impossible to use the weathered deposits for volumetric calculations of retreat rates. lichen is very sparse on the faces of the coastal cliffs, thereby also denying lichenometry as an option. the length of the abrasion platform at the sites is 10–15 m, but because of the limited knowledge of the sea level after the tapes transgression (forman et al. 1987), and with the possibility of the present sea level occupying a pre-holocene cliff, it is difficult to calculate an average holocene retreat rate (ødegård & sollid 1993). another approach for measuring coastal erosion is remote sensing. satellite remote sensing and aerial photogrammetry have been successfully used in arctic coastal change studies (grosse et al. 2005; lantuit & pollard 2005; mercier & laffly 2005). digital photogrammetry, using either terrestrial or aerial photographs, depending on the scale of the feature investigated, has become a valuable tool in geomorphology (pyle et al. 1997; chandler 1999; lane et al. 2000; baily et al. 2003; chandler et al. 2003; lim et al. 2005). because retreat rates of coastal cliffs in kongsfjorden are expected to be small, satellite remote sensing and aerial photogrammetry cannot provide the required accuracy for the timescale available. however, terrestrial photogrammetry with camera–object distances of around 10 m can provide the millimetre–centimetre accuracy needed to measure the expected coastal cliff retreat rates. the aim of this study is to quantify the retreat rates of two coastal cliff sites in the kongsfjorden area using multi-temporal terrestrial photography and digital photogrammetry. study area the kongsfjorden area is situated on the western coast of spitsbergen, the largest island of the svalbard archipelago (fig. 1). svalbard is located between 74–81 ° n and 10– figure 1 map of svalbard and the kongsfjorden area. the square on the index map represents the research area. l shows the location of longyearbyen, t and w are the fjords tempelfjorden and wijdefjorden, respectively, and f is the island prins karls forland. 16 polar research 26 (2007) 14 – 21 © 2007 the authors coastal cliff retreat in kongsfjorden, svalbard b. wangensteen et al. 35 ° e in the north atlantic. glaciers of different types cover 60% of the 66 000-km 2 archipelago (hagen et al. 1993). the mean annual air temperature (maat) in ny-ålesund is − 6 ° c and the mean annual precipitation 370 mm (førland & hanssen-bauer 2000). the tidal range in ny-ålesund is 1.8 m on average; 2.3 m is the maximal tidal range. the average high tide is 0.6 m above mean sea level (ødegård & sollid 1993). the area has continuous permafrost with measured depths ranging from 130 to 150 m near the shores of ny-ålesund (orvin 1944; liestøl 1977). the mean annual ground temperature (magt) is believed to be about − 5 ° c based on measurements in a former coal mine (orvin 1944). the two sites investigated in this study (fig. 1) are both close to ny-ålesund and consist of low cliffs in bedrock, with unconsolidated material on top, and with sandy and stony beaches in front (ødegård et al. 1987). site 2 is located within a small bay and is less exposed than site 1, which is located further out the fjord, with a much longer fetch. the bedrock of both investigated sites is made up of dolomitic limestone of middle carboniferous to early permian age. the unconsolidated material of 1–2 m in thickness found on the top of the bedrock cliffs are marine deposits of quaternary age (hjelle et al. 1999). the dimension of the areas analysed are 2.8 by 3.6 m at site 1 and 2.2 by 2.4 m at site 2. the investigations are limited to the bedrock part of the cliffs. coastal geomorphology maps of svalbard, excluding nordaustlandet, reveal well-developed coastal cliffs along 27% of the coastline, and another 13% with rocky shores (etzelmüller et al. 2003). low vertical cliffs are most frequent in the fjord areas in north-western spitsbergen. this means that the chosen area is representative of a large portion of the coastline of svalbard and an even greater portion of the fjord areas. however, one should bear in mind that bedrock properties and marine processes vary greatly within the same coastal type. the percentage of arctic coasts that are cliffed and rocky is not known, but these coast types comprise threequarters of the world’s coastline (bird 2000). photograph acquisition and digital terrain model (dtm) differencing photographs with stereo coverage were acquired with a 60-mm analogue hasselblad camera at each site in august 2002 and august 2004. the camera–object distances were 15 m at site 1 and 7 m at site 2. the geometry of the camera set-up is shown in fig. 2. at both sites a bolt was drilled into a bedrock outcrop. the position of the bolt was measured by global positioning system (gps) and served as a fixed point for reference to global mapping coordinate systems. the positions of the camera stations were also measured using relative gps and by a theodolite and an electronic distance measurer from the fixed point to tie both to a global and a local reference. at both sites the bolts that were to be used as photogrammetric control points were also drilled into the cliff wall. these fixed points were surveyed from the camera stations and the camera was mounted on top of the theodolite with a special device. this makes it possible to ensure parallel photograph directions. the photographs where scanned at a resolution of 6.25 µ m (4000 dpi) and imported into the z/i imagestation digital photogrammetric workstation (dpw) software. the scale of the photographs acquired was 1 : 250 and 1 : 117 for sites 1 and 2, respectively. the scanning resolution therefore gives xy resolutions of 1.6 and 0.7 mm for sites 1 and 2, respectively. a local coordinate system was established to simulate aerial photogrammetry, with the z -axis is pointing out of the cliff and the xy plane vertical behind the cliff wall and also parallel to the figure 2 the photograph stations were deployed 7–15 m from the cliff wall and 3.5– 7.5 m apart. the photographic coverage is shown on the cliff wall. the investigated area is the area covered by both photographs. b. wangensteen et al. coastal cliff retreat in kongsfjorden, svalbard polar research 26 (2007) 14 – 21 © 2007 the authors 17 photograph base (fig. 2). all coordinates were also scaled by a magnitude of 100 to simulate reasonable “flying heights”. the photograph pairs have been used to create photogrammetric stereo models using the surveyed bolts in the cliff wall as pass points. a high precision dtm was generated for each site using the automatic elevation point collector module in the dpw. the x y resolutions of the models created were 2 and 1 cm for sites 1 and 2, respectively. to ensure the high quality of the dtms, the photogrammetric models from different years at the same site were tied together using the same control points and five additional tie points located in stable parts of the cliff. the retreat rate was simply found by differencing the 2002 and 2004 models using the geographic information system arcinfo workstation (esri, http:// www.esri.com/). using terrestrial digital photogrammetry with a similar approach, and evaluating the results, pyle et al. (1997) infer a dtm accuracy of 12 mm with a 15-m camera– object distance and point out that this accuracy of 1/1000 of the camera–object distance is in the lower end of the accuracies achieved by aerial photogrammetry. this relatively large relative error is attributed to errors in the estimates of ground point positions being much larger relative to the camera–object distance for close-range photogrammetry. using a digital camera and a 1.6-m camera–object distance, chandler et al. (2003) found an elevation root mean square (rms) error of 1. mm, corresponding to 12 parts per 10 000. no direct evaluation of the dtm accuracy was performed in this study, but it is reasonable to believe that they are close to the findings of pyle et al. (1997). using the values found by pyle et al. (1997) the total differentiation error would be 10.6 mm y − 1 for site 1 and 4.9 mm y − 1 for site 2. the rms values calculated for the combined absolute orientation of the 2002 and 2004 models within the dpw are 3, 4 and 3 mm for x , y and z , respectively at site 1 and 2, 3 and 6 mm at site 2. this means that the accuracy should be 10 mm or better for the yearly retreat values. lens distortion and focal length were not known for the camera at the time when the study was performed, but has subsequently been the subject of a master’s thesis (odberg 2006). not knowing the exact focal length will lead to an error in the z direction and therefore also an error for the retreat. as the same camera was used both times, and the photographing position (to within centimetres) and the photographing direction were also the same, this would not lead to any errors in the calculation of retreat because the errors will be exactly the same for the photographs taken in 2002 and 2004. it would be likewise for the lens distortion, which leads to errors in x and y as well, but the change of the lens from 2002 and 2004 is insignificant. coastal cliff retreat rates the automatically generated 2004 dtms for sites 1 and 2 are shown in fig. 3 as shadowed relief models. the differencing of the dtms reveal an average retreat of 3.1 mm y − 1 for site 1 and 2.7 mm y − 1 for site 2 (fig. 4). the average retreat rate is calculated as the volume difference between the two time periods divided by the investigated area of the cliff. at site 1 parts of the cliff wall was hidden behind boulders, and these areas were excluded from the retreat rate calculation. both difference models show retreat occurring in spots, with maximum retreat rates of 125.0 and 42.0 mm y − 1 for sites 1 and 2, respectively. the other retreat spots at both sites 1 and 2 are in areas where the cliff is quite planar, and therefore show flaking rather than small rockfalls (fig. 5). orthophotographs of site 1 from 2002 and 2004 show a loss of material in front of the cliffs between the two acquisitions. the volume of the removed boulders along the 6.5 m distance with stereo coverage is estimated to be about 0.6 m 3 based on photogrammetric stereo measurements. as the boulders are located in front of the cliff it is figure 3 digital terrain models (dtms) of (a) site 1 and (b) site 2 from 2004 shown as shadowed relief models. http:// 18 polar research 26 (2007) 14 – 21 © 2007 the authors coastal cliff retreat in kongsfjorden, svalbard b. wangensteen et al. not possible to measure them using dtm differencing, and this area is therefore excluded from the dtm differencing presented in fig. 4. the blocky material that has been removed from the beach at site 1 is also marked in fig. 5. there was no blocky material in front of site 2, and therefore only the retreat rates of the cliff itself were calculated (fig. 6). discussion dtm differencing accuracy looking at either rms values from the orientation of the model or using the values computed using either chandler et al. (2003) or pyle et al. (1997), the accuracy of the applied method is 10 mm or better for yearly retreat rates at both sites. as an additional check of the accuracy, semivariograms were made for the retreat rate grids. in these grids all points with retreat rates above 10 mm y − 1 were left out. semivariograms are used in geostatistics to evaluate spatial dependency in data sets (burrough 1990) and are plots of the semivariance as a function of distance. the difference between the nugget (a measure for variance caused by noise in the data) and the sill (a measure for the variance level at the distance where the spatial dependence ceases) can be taken as an indicator for the overall spatial dependency in the data. at both sites there was a relatively small difference between the sill and the figure 4 retreat rates from (a) site 1 and (b) site 2 draped over the 2004 relief models. figure 5 orthophotograph of site 1 in 2004 showing areas of retreat and block removal. b. wangensteen et al. coastal cliff retreat in kongsfjorden, svalbard polar research 26 (2007) 14 – 21 © 2007 the authors 19 nugget values, namely 4% for site 1 and 20% for site 2, meaning that there is only a small spatial dependency in the data set for values below the believed accuracy, and that the retreat rates should be valid as volume measures and not only as point measures. hence, no spatial trends in the data sets were found. it is worth noting that the semivariograms and the rms values from the orientation show that the data set from site 1 is more accurate than that from site 2, even though site 1 has twice the camera–object distance compared with site 2. this might be a result of there being fewer fixed points used for orientation at site 2, and hence a less accurate orientation of the models. as noted earlier, most of the retreat detected in this study takes place in concentrated and rather small areas and with a retreat rate greater than the accuracy, indicating that the overall retreat rates are significant. retreat rates compared with the findings of rapp (1960), andré (1997), berthling (2001) and prick (2004), the results from this study show somewhat higher retreat rates. andré (1997) found retreat rates of up to 1.58 mm y − 1 , but attributes only a small portion of these rates to currently active frost shattering, namely 0.07 mm y − 1 in average for amphibolite in wijdefjorden, and 0.16 mm y − 1 for quartzite in kongsfjorden. rapp (1960) reported a rock wall retreat rate of 0.02–0.20 mm y − 1 for the sand and limestone in tempelfjorden, and 0.50 mm y − 1 for a nunatak in the same area. berthling (2001) reported rock wall retreat rates of 0.3–0.6 mm y − 1 based on volume and age estimates of rock glaciers on prins karls forland in an area of quartzite bedrock. none of these localities are exposed to marine processes and are therefore not directly comparable with the results from this study. prick (2004) reports a rate of 1.9 mm y − 1 for a sandstone and shale cliff wall in longyearbyen, which is the most similar site compared with the ones we investigated in terms of process and bedrock composition. the differences between the results found in this study and the earlier works of rapp (1960), andré (1997) and berthling (2001) can be attributed to differences in the effectiveness of the rock wall retreat processes involved compared with coastal processes. the smaller retreat rate found by prick (2004) may be explained by differences in bedrock. her study focused on bedrock that is somewhat less susceptible to weathering. according to sunamura (1992), however, cliffs consisting of shale and sandstone should be more susceptible to coastal erosion than limestone. the site investigated by prick (2004) has been protected from these processes for a decade, whereas the locations used in this study are currently influenced by marine processes. marine cliffs in general show a variety of erosion rates caused by lithology, from several metres per year for regolith, to 4 mm y − 1 and upwards for rocks of medium to hard rock cliffs unaffected by erosion (young & saunders 1986). sunamura (1992) lists worldwide linear cliff recession rates and found the following average rates: 1 mm y − 1 for granite, 1–10 mm y − 1 for limestone and 1 cm y − 1 for shale. cold regions exhibit higher retreat rates and allard & tremblay (1983) found erosion rates in the order of 10 mm y − 1 for a basaltic bedrock coast by hudson bay in northern quebec, canada. they attribute this to the joint actions of waves, sea ice and frost shattering. it is reasonable to believe that chemical weathering is more active in the coastal zone compared with areas not influenced by the sea. as carbon dioxide is more soluble at colder temperatures one should expect higher rates of chemical erosion in arctic marine environments (williams 1949). at a non-coastal locality, chemical erosion rates of 2 mm per thousand years have been found, whereas rates in marine polar areas may be at least two magnitudes greater (corbel 1959). therefore, chemical weathering accounts for a negligible portion of the coastal cliff retreat rates measured in this study. it is important to bear in mind that the measurements that form the base of this study were performed only at figure 6 orthophotograph of site 2 in 2004 showing areas of retreat. 20 polar research 26 (2007) 14 – 21 © 2007 the authors coastal cliff retreat in kongsfjorden, svalbard b. wangensteen et al. two selected localities and on only a few metres of coastline. as the processes governing coastal cliff retreat probably vary considerably both spatially and temporally, because of variations in sea-ice cover, snow cover, bedrock and existence of the ice-foot, as well as with wave activity and storminess, the retreat rates will also show a huge variation. earlier studies for instance show a considerable spatial and temporal variation in sea-ice and icefoot conditions in the kongsfjorden area (wiseman et al. 1981) and other places in svalbard (feyling-hansen 1953). weather data from the meteorological station in ny-ålesund show that the temperature, precipitation and wind in the investigated period from august 2002 to august 2004 did not differ largely from the general climate deduced from meteorological observations undertaken by the norwegian meteorological institute since 1974 (data accessed at http://eklima.met.no for station no. 99910). the greatest deviations from the general climate are found for temperature in late 2002, showing temperatures of 4.6 and 5.4 ° c above the mean temperatures for november and december, respectively, although the temperatures remained well below 0 ° c. these months also show higher values for precipitation, meaning more snowfall. whether this led to either a greater snow thickness or longer snow cover duration in the following spring at the investigated sites is unknown. there are no observations of sea-ice distribution available. to assess reliable retreat rates a long-term programme, preferably also including more sites, should be undertaken. monitoring of temperature, snow, sea-ice cover and wind at the investigated sites would also be a requirement. traditional geomorphologic estimates of coastal retreat rates at a scale of either millimetres or centimetres per year are based on a longer period of time than two years, and the uncertainty of those are mainly caused by uncertainties of the time horizon (i.e. dating). the advantage of using volume-/time-based retreat rates is that the yearto-year variation in the processes governing weathering and coastal processes is better dealt with. as noted earlier, the uncertainty of the sea level development since the tapes transgression in the investigated area makes it difficult to estimate the holocene retreat rate using these traditional methods (forman et al. 1987). however, terrestrial photogrammetry makes is possible to perform spatially detailed studies of retreat rates and to map more short-term temporal variations. conclusion the method of close-up digital terrestrial photogrammetry seems suitable for creating accurate dtms of coastal cliffs and for calculating retreat rates on the order of millimetres–centimetres. differencing of multi-temporal dtms reveal retreat rates of 3.1 and 2.7 mm y − 1 for two costal cliff locations in the kongsfjorden area in western spitsbergen, svalbard. the retreat occurs in spots and the processes involved seem to be both flaking and small rock falls. compared with rock wall retreat rates found elsewhere in svalbard, the rates are quite high. this could be because other investigations were performed in noncoastal environments or because there were other natural processes involved. two years is too short a time interval for investigating coastal cliff retreat rates. nevertheless, the retreat rates found are within the range of worldwide averages for limestone cliffs. removal of weathered material at the base of the coastal cliffs is considered to be important in the retreat process, and is documented through the multi-temporal photography obtained at one of the sites. acknowledgements the fieldwork was financially supported by the intas project arctic coasts of eurasia: dynamics, sediment budget and carbon flux in connection with permafrost degradation (intas-2001-2329) and the norwegian research council on behalf of the norwegian polar committee. the improvements suggested by the referees steven solomon and hugues lantuit are also greatly acknowledged. references allard m. & tremblay g. 1983. les processus d’érosion littorale périglaciaire de la région de poste-de-la-baleine et des îles mnaitounuk sur la côte est de la mer d’hudson, canada. (littoral periglacial erosion processes in the region of postede-la-baleine and the mnaitounuk islands on the coast of hudson bay, canada.) zeitschrift für geomorphologie, supplementband 47 , 27–60. andré m.-f. 1997. holocene rockwall retreat in svalbard: a triple-rate evolution. earth surface and processes and landforms 22 , 423–440. baily b., collier p., farres, p., inkpen r. & pearson a. 2003. comparative assessment of analytical and digital photogrammetric methods in the construction of dems of geomorphological forms. earth surface and processes and landforms 28 , 307–320. berthling i. 2001. slow periglacial mass wasting—processes and geomorphological impact. case studies from finse, southern norway and prins karls forland, svalbard . msc dissertation, university of oslo, norway. bird e. 2000. coastal geomorphology: an introduction . chichester, uk: wiley. burrough p.a. 1990. principles of geographical information systems for land resource assessment . oxford, uk: clarendon press. http://eklima.met.no b. wangensteen et al. coastal cliff retreat in kongsfjorden, svalbard polar research 26 (2007) 14 – 21 © 2007 the authors 21 chandler j. 1999. effective application of automated digital photogrammetry for geomorphological research. earth surface and processes and landforms 24 , 51–63. chandler j.h., buffin-bélanger t., rice s., reid i. & graham d.j. 2003. the accuracy of river a bed moulding/casting system and the effectiveness of a low-cost digital camera for recording river bed fabric. photogrammetric record 18 , 209– 223. corbel j. 1959. vitesse de l’érosion. (erosion rates.) zeitschrift für geomorphologie 3 , 1–28. etzelmüller b., øård r.s. & sollid j.l. 2003. the spatial distribution of coast types on svalbard. in v. rachold et al . (eds.): arctic coastal dynamics report of the 3rd international workshop university of oslo (norway) 2–5 december 2002 . bremerhaven: alfred wegener institute for polar and marine research. feyling-hansen r.w. 1953. brief account of the ice-foot. norsk geografisk tidsskrift, norwegian journal of geography 14 , 45–52. førland e.j. & hanssen-bauer i. 2000. increased precipitation in the norwegian arctic: true or false? climatic change 46 , 485–509. forman s., mann d.h. & miller g.h. 1987. late wechselian and holocene sea-level history of brøggerhalvøya, spitsbergen. quaternary research 27 , 41–50. grosse g., schirrmeister l., kunitsky v.v. and hubberten h.-w. 2005. the use of corona images in remote sensing of periglacial geomorphology: an illustration from the ne siberian coast. permafrost and periglacial processes 16 , 163–172. hagen j.o., liestøl o., roland e. & jørgensen t. 1993. glacier atlas of svalbard and jan mayen. norsk polarinstitutt meddelelser 129 . oslo: norwegian polar institute. hjelle a., piepjohn k., saalmann k., ohta y., salvigsen o., thiedig f. & dallmann w.k. 1999. geological map of svalbard 1 : 100,000 sheet ag7 kongsfjorden . tromsø: norwegian polar institute. høgbom b. 1914. ûber die geologische bedeutung des frostes. (the geological importance of frost.) bulletin of the geological institution of the university of upsala 12 , 257–389. lane s.n., james t.d. & crowell m.d. 2000. application of digital photogrammetry to complex topography for geomorphological research. photogrammetric record 16 , 793–821. lantuit h. & pollard w.h. 2005. temporal stereophotogrammetric analysis of retrogressive thaw slumps on herschel island, yukon territory. natural hazards and earth system sciences 5 , 413–423. liestøl o. 1977. pingos, springs, and permafrost in spitsbergen. norsk polarinstitutt årbok 1975 , 7–29. lim m., petley d.n., rosser n.j., allison r.j., long a.j. & pybus d. 2005. combined digital photogrammetry and timeof-flight laser monitoring for cliff evolution. photogrammetric record 20 , 109–129. mercier d. & laffly d. 2005. actual paraglacial progradation of the coastal zone in the kongsfjorden area, western spitsbergen (svalbard). in c. harris & j.b. murton (eds.): cryospheric systems: glaciers and permafrost . pp. 111–117. london: geological society. nansen f. 1922. the strandflat and isostasy. videnskapsselskapets skrifter i, matematisk-naturvidenskapelig klasse 1921, 2. kristiania: j. dybwad. nielsen n. 1979. ice-foot processes. observations of erosion on a rocky coast, disko, west greenland. zeithschrift für geomorphologie 23, 321–331. odberg t. 2006. kalibrering av ikke-metriske kamera. (calibration of non-metrical cameras.) msc thesis. department of geosciences, university of oslo, norway. ødegård r., sollid j.l. & trollvik j.a. 1987. coastal map svalbard a 3 forlandssundet 1 : 200,000. department of physical geography, university of oslo, norway. ødegård r.s., etzelmüller b., vatne g. & sollid j.l. 1995. nearsurface spring temperatures in an arctic coastal cliff: possible implications of rock breakdown. in o. slaymaker (ed.): steepland geomorphology. pp. 89–102. chichester, uk: wiley. ødegård r.s. & sollid j.l. 1993. coastal cliff temperatures related to the potential for cryogenic weathering processes, western spitsbergen, svalbard. polar research 12, 95–106. orvin a.k. 1944. litt om kilder på svalbard. (the springs of svalbard.) norsk geografisk tidskrift, norwegian journal of geography 10, 6–38. prick a. 2004. observations of rock temperatures and rock moisture variability in longyearbyen: implications for cryogenic weathering and rock wall retreat rate. abstracts of pace 21: permafrost and climate in the 21st century. field workshop longyearbyen, svalbard, 8–13 september 2004. p. 16. longyearbyen: university courses on svalbard. pyle c.j., richards k.s. & chandler j.h. 1997. digital photogrammetric monitoring of river bank erosion. photogrammetric record 15, 753–764. rachold v., are f.e., atkinson d.e., cherkashov g. & solomon s.m. 2005. arctic coastal dynamics—an introduction. geomarine letters 25, 63–68. rapp a. 1960. talus slopes and mountain walls at tempelfjorden, spitsbergen—a geomorphological study of the denudation of slopes in an arctic locality. meddelanden uppsala universitets geografiska institution 55a. uppsala: uppsala university. soluri e.a. & woodson v.a. 1990. world vector shoreline. international hydrographic review 67, 27–36. sunamura t. 1992. geomorphology of rocky coasts. (coastal morphology and research.) chichester, uk: wiley. williams j.e. 1949. chemical weathering at low temperatures. geographical review 39, 129–135. wiseman w.j., owens e.h. & kahn j. 1981. temporal and spatial variability of ice-foot morphology. geografisk annaler 63a, 69–80. young a. & saunders i. 1986. rates of surface processes and denuation. in a.d. abrahams (ed.): hillslope processes. pp. 3– 27. boston, ma: allen & unwin. an ice drift series from the fram strait january-march 1992 based on ers-1 sar data reinert korsnes korsnes, r. 1994: an ice drift series from the fram strait january-march 1992 based on ers-1 sar data. polar research 13. 55-58. a time series of ers-1 sar images is used to estimate ice drift in the fram strait january-march 1992 (the ers-1 mission first ice phase). the images all cover the same area. the sampling interval is three days. the paper shows examples of estimation of ice drift and divergence from this image time series. divergence is an important quantity in order to cstimate ice production and hence mixing of the ocean water masses. a reference configuration of ice points is defined for each image. these ice points are identified in the successive image giving a set of point pairs. these point pairs are input for statistical analysis. upward looking sonars (uls) and current meters are moored below the scene. a combination of the sar derived dynamics and the uls derived ice thickness series will give opportunities to estimate ice mass flux into the greenland sea, and t o improve ice classification algorithms. r . korsnes, norsk polarinsritutt. p . 0. box 5072, n-0501 oslo, n o r w a y . introduction this paper gives results from work demonstrating modes as in the taylor-like expansion: t,,.,*(x) = 9 + a ( x 9 + e (1) . . the feasibility of using ers-1 sar imagery data where and to estimate temporal variations of ice velocities in the east greenland ice stream. this ice stream represents about 95 percent of all the ice that are mean points of a reference configuration of corresponding ice points at times f , and f2 respectively. a is a matrix. is an leaves the arctic ocean (vinje & finnekba 1986) and is therefore an important climatic parameter. a time series of ers-1 sar images covering the same area of 100 x 100 square kilometres and spatial resolution of about 30 metres is used to estimate ice drift in the fram strait january march 1992. fig. 1 shows the spatial outline for this image time series. the sampling interval is three days. analysis method let x, denote the set of all ice particles at time f in the actual region including the frame of obser vation z, that also may depend on the time t . we may regard z, and x, as subsets of the plane r2 (x,, z, c r2). we want a sensible probabilistic and physical interpretation of the transformation the times i, and 1,. a first approach may be to represent t,,,,, by the shift, stretch and rotation tl,,t, which maps corresponding ice points between fig. 1 . spatial coverage of ers-1 s a r image time series used to estimate ice drift in the fram strait january-march 1992 (satellite mission first ice phase). 56 r . korsnes error or model failure term. rothrock & stern (1992) obtained the invariants uorticity , diuer gence and shear by interpreting the terms of the matrix a as the partial derivatives of a velocity field (a direct use of equation 1). their work is based on seasat sar images 19 july-7 octo ber, 1978. loshchilov et al. (1980) made similar approaches twelve years earlier using slar (the author was shown during a stay at the arctic and antarctic research institute, aari, in st. petersburg, june 1992). the vector b = 9 reflects ice drift. the transformation a maps a unit circle into an elipsis with axes of length ui(a) = {ai(a7a}1/2, i = 1,2, where ai(a7a) are the eigenvalues with the cor responding eigenvectors ei of the symmetric, posi tive semidefinite, matrix ata. we assume a1 3 h2. ui(a) are in the literature called singular ualues of the matrix a (cf. e.g. ciarlet 1988, chapter 3). we can interprete ul(a)u2(a) as the increase of area between the image sample times. let a = c u (2) be the (unique) polar factorization of (the invert ible) matrix a where c is a rotation and u is a positive definite matrix (note: we can assume determinant (a) > 0). u reflects deformation given by its eigenvalues ui,i = 1,2, and direction el of the eigenvector e l . the measure for approximation in this paper is the common method of least square. a reference configuration {xi} of ice points is defined for each image. each ice point xi, is in the successive image table 1: estimates of three days ice drift in the east-greenland ice stream january-march 1992 based on ers-1 sar data (satellite mission first ice phase). each 3 days period is labeled by its start date. = means analysis performed by eye due to too little common ice in image pair. blank means missing data. angles are given relative to north (positive clockwise). @esa (1992). drift (b) deformation (u) mean date velocity length dir 8, (1992) (m/s) (km) (deg) 01 0 2 (deg) 01.09 .24 61 221 1.00 1 .00 102 01.12 =.35 -90 -200 01.15 z.35 =90 -200 01.18 .18 46 200 1.15 .79 112 01.21 .14 36 181 1.01 .91 33 01.24 .14 38 194 1.01 .99 43 01.27 .33 85 205 1.01 .99 -21 01.30 .i7 44 1% 1.03 .96 124 rotation c error e (deg) (m) prediction -1.6 33 0.1 715 -6.3 764 6.6 214 3.2 204 7.7 24 1 02.02 .17 44 02.05 .19 49 02.08 .27 71 02.11 .09 23 02.14 .09 23 02.17 .10 25 02.20 .27 70 02.23 02.26 02.29 ~ 191 1 .00 .97 17 7.4 192 184 1.42 .68 101 -14.6 789 1% 1 .w .99 4 9.2 37 177 1.11 1 .o 131 3.5 355 184 1.49 1.01 96 7.8 1(n6 206 1.39 .62 122 15 1335 224 1.04 .87 49 8.6 323 03.03 03.06 03.09 .31 81 199 1.15 .82 127 9.3 80 1 03.12 03.15 03.18 .29 76 186 1.04 .88 112 8.0 285 03.21 .i7 44 180 1.01 .97 114 12.4 377 03.24 .22 56 192 1.00 1 .00 -12 9.1 39 03.27 .16 41 192 1 .00 .99 119 6.1 49 an ice drift series from the fram strait 57 fig. 2. development of regular grid of ice points s 1 2 march 1992. the images cover 20 x 20 square kilometre subsets of the original ers-1 sar scenes. only the points with significant identification confidence are shown in the right image from 12 march. the image is received and processed at tss. oesa (1992). identified as yi with a weight of confidence mi between 0 and 1. the estimates for a minimize the mean square prediction error: observation code based on physical insight. as such, equation 1 gives an a d hoc description of ice drift t,1,t2 without any a priori relevance for significant data reduction. decomposition of drift into tidal components and residual drift in principle would give results more independent on ad hoc sampling time e z d e f c ly; a(xi -f) y12mi/%i (3) in the present analysis the points yi were identified by a semi-automatic procedure based on cross correlation. the author manually checked the results. if any doubt about the value of yi the weight m, was set to 0 (otherwise 1). the reference configuration of moving ice points in this case is a regular grid of 121 points covering about 10 x 10 kilometre as illustrated in figs. 2 and 3. the observation times t , < . . . < t , have a constant sampling interval ti + i ti = 6t of three days. table 1 shows the, preliminary, result from this analysis. i i discussion the aim for the analysis of this paper is to give a the ice drift in the actual region. time and spatial fig. 3. development of regular grid s 1 2 march 1992 (geo are slightly different due to rudimentary data collection timing representative and general purpose for coded) estimated from ers-1 sar data, the image coverages aspects are to be considered when setting up an code (later improved). o e s a ( 1 9 2 ) . 58 r. korsnes schemes. however, tidal estimates for the actual location are minor to the normal mean drift (cf. schwiderski, 1980). the estimates of a and b may be sensitive to the choice of the initial reference configuration of ice points { x i } . a grid covering a small area often will reflect rigid motion of ice floes and spatial shifts of the grid will give variations of the drift term b reflecting divergence in the ice field. this approach may lead to statistical techniques on ice classification and description based on the identification of rigid sets. a final report with the present approach will include relations between grids of varying size and location in order to provide a general purpose statistical description of the ice dynamics of the region in the freezing season. acknowledgemenfs. -the data used in this report were provided partly free of charge derived from the ers-i satellite payload in response t o the announcement of opportunity for ers-1 (a.o.), issued by the european space agency on 20 may, 1986. the norwegian polar institute joins the esa programme for international polar ocean research (pipor) as ers-1 experiment iceclima-n8. i acknowledge the norwegian space ccntrc for the oppor tunity to work on these till now unique data sets. i specially thank staff at tromse satellitte station (tss) for good com munication and the foresighting extra service of collecting and storing of more data than first requested. references ciarlet, g . c. 1988: three-dimensional elasficify, vol. 1 of marhematical elasficify. elsevier science publishers b.v., amsterdam. loshchilov, v. s., voevodin, v. a . & borisov, r . a. 1980: pnmenenie samoletnoi radiolokatsionnoi sfanfsii bokouogo obzora dla issledouanija morskin ldou (the use of slar for sea ice research), vol. 12 of mezvedomfuennyi sbornik issledooanie mirouogo okeana. leningradskyi polytech nicheskyi institute, leningrad. rothrock, d. a. & stern, h. l. 1992: sea ice deformation observed with ers-i sar. in proceedings of the firsf ers-i symposium: spaceaf the service of our environment, cannes, france. schwiderski. e . w. 1980: reviews of geophysics and space physics. on charring global ocean rides. 18(1): 243-268. feh ruary 1980. vinje, t. & finnekasa 1986: the ice transport through the fram strait. technical report 186. norsk polarinstitutt, oslo. por_029.fm polar research 26 2007 195 – 203 © 2007 the author 195 bones h i s to r i c a l / b i o g r a p h i c a l e s s ay norway and past international polar years—a historical account stian bones norwegian polar institute, polar environmental centre, no-9296 tromsø, norway. surveying norway’s role in past international polar years (ipys), this essay by historian stian bones contributes to a broader understanding of norway as a “polar nation”. he describes the strengths of norway’s scientific traditions in the polar regions, and examines the varying motivations driving norwegian involvement in the first three ipys: 1882–83, 1932–33 and 1957–58 (also known as the international geophysical year). —the editor keywords international polar year; international geophysical year; norwegian history; history of science. the first international polar year (ipy) lasted from 1 august 1882 to 31 august 1883. twelve nations participated in this groundbreaking international cooperative project, establishing 14 research stations: 12 in the arctic and two in the southern hemisphere (the danish research vessel the dijmphna can be counted as an additional station). the roots of this huge scientific endeavour are to be found in 1875, when the austro-hungarian polar expedition (1872–74) returned home after having, among other achievements, officially discovered franz josef land (payer 1876). international cooperation and coordination was the only way to solve the great scientific problems in the field of meteorology and geophysics, according to the expedition’s co-commander lt carl weyprecht. weyprecht, a renowned polar scientist and explorer, claimed that too much money and effort were spent on mapping, naming and conquering the frozen territories in the names of different nations. science suffered from this. in his talk to the royal geographical society in london, he said, decisive scientific results can only be attained through a series of synchronous expeditions, whose task it would be to distribute themselves over the arctic regions and to obtain one year’s series of observations made according to the same method. (quoted in baker 1982: 276) in the following years—and with help from count hans wilczek—weyprecht developed his ambitious plan further. by the spring of 1877 he was ready to present it before the international meteorological congress. unfortunately, because of the war in south-eastern europe, the congress was not able to assemble in rome until the spring of 1879. serving the international meteorological congress was a permanent committee, or secretariat, which prepared the cases to be considered by the congress and followed up the resolutions that were passed. among those seated in the permanent committee was the leading norwegian geophysicist henrik mohn, director of the norwegian meteorological institute (det norske meteorologiske institutt), who had agreed to prepare a recommendation for the congress regarding weyprecht’s proposal (steen 1881) (fig. 1). the committee supported weyprecht’s initiative and it was recommended to all governments. the congress appointed an international meteorological commission to follow up the idea. the commission sent out invitations to the first international polar conference in hamburg, to be held on 1–5 october 1879. representatives from denmark, france, the netherlands, norway, russia, sweden, austria–hungary and germany were present. the conference dealt with a wide range of details concerning the plans for an ipy, and it also constituted a permanent international polar commission, with the german polar explorer and scientist georg von neumayer as its president. the representatives of various countries attending the international polar conference now had to investigate whether there was sufficient economic support in the participating nations for an ipy from 1 september 1881 to 31 august 1882. at the second international polar conference in bern, only three or correspondence norwegian polar institute, polar environmental centre, no-9296 tromsø, norway. e-mail: bones@npolar.no doi:10.1111/j.1751-8369.2007.00029.x 196 polar research 26 2007 195 – 203 © 2007 the author norway and past international polar years s. bones four countries were able to confirm sufficient economic backing from their governments, and it was decided that the ipy had to be postponed until 1882–83. the whole idea seemed to be hanging on a thread. in january 1881 there were still only five countries that were able to confirm economic support for their polar stations, namely russia, austria–hungary, sweden, denmark and norway. in spite of this, the president of the international meteorological commission, professor heinrich wild of st petersburg, pushed forward a resolution saying that the ipy was to be arranged even if only five countries could take part. norway was the only country that resisted this decision. professor mohn said that the norwegian parliament had given its grant on the premise of a minimum of eight participating countries. the best he could do, mohn said, was to delay the deadline for norway’s final decision until 1 may 1881. during the winter of 1881 it seemed that plans for the ipy had come to a standstill, a situation that was not improved with the death of carl weyprecht on 29 march. but his idea proved to be blessed with good fortune, and on 14 may 1881 professor wild announced that at least eight stations would be carrying out simultaneous observations during the ipy. norway’s involvement in the first ipy, 1882–83 during the first ipy, norway established her station in bossekop, in the northern district of alta, with an auxiliary station in kautokeino (fig. 2). the site was pointed out by henrik mohn, who also procured most of the necessary scientific equipment. some of the instruments were even designed on the basis of mohn’s drawings (engelbrethsen 1895). but why bossekop? mohn had considered three geographical alternatives within the auroral zone, all possibly well suited for studies of terrestrial magnetism, meteorology and the northern lights, and all well north of the arctic circle: hammerfest, tromsø and bossekop. two factors favoured bossekop. first, the percentage of cloud cover was less in the bossekop area compared with the other two possible sites. second, bossekop had been the base for similar studies before (steen 1881; tromholt 1885). the most important research expedition in this part of the arctic had been the great french expedition with la recherche , which explored northern norway, the white sea, spitsbergen and bjørnøya (bear island) from 1838 to 1840. (for norwegian studies of the la recherche expedition, see drivenes 1992 and knutsen & posti 2002.) during the winter of 1838–39, the la recherche expedition established a station in bossekop, with the main task of studying terrestrial magnetism and the aurora borealis. five members of the expedition were stationed in bossekop, namely the french physicists bravais and lottin, the swedish physicists lilliehöök and siljeström, and the french illustrator bevalet. the scientific observations made by this expedition were carried out by the small scientific society at the kåfjord copper fig. 1 professor henrik mohn (1834–1916). (courtesy of the norwegian polar institute picture library.) fig. 2 the norwegian polar station in bossekop. some of the meteorological instruments and the magnetic hut can be seen. the breverud farm was rented for 800 kroner per year. (photo by sophus tromholt, courtesy of the university of bergen library.) s. bones norway and past international polar years polar research 26 2007 195 – 203 © 2007 the author 197 mine, near bossekop, for another four years, which completed a five-year observation series. later, the scientific society extended the observations for another five years. the new norwegian polar station established for the first ipy was to be managed by aksel s. steen, assistant director of the norwegian meteorological institute. as had been the case for the expeditions, the main task for the norwegian scientists was to make observations of terrestrial magnetism and meteorology, and to study the northern lights. steen, a climatologist, had to build up his knowledge of terrestrial magnetism before he could begin. by 1882, the leader of the norwegian team was well prepared for the task ahead of him. because of the postponement of the ipy there was plenty of time for planning. steen and his companions took the opportunity to investigate the area around the farm called breverud beforehand, deciding where the different buildings should be placed. some of the observatories that were built in bossekop were, in fact, prefabricated. to avoid interference with the instruments in the magnetic hut, it was important not to use any iron nails in the construction of the facilities—only wooden nails, and some copper and brass (tromholt 1885). in july 1882 all five of the norwegians who would man the bossekop station were settled there: aksel steen, carl krafft, jens schroeter, ivar hesselberg and olaf hagen. steen took care of the absolute magnetic observations (barr 1985). krafft handled the auroral observations and the measurements of relative and absolute humidity; he was also the station photographer. along with steen, schroeter was in charge of the astronomical observations; he also saw to it that the chronometers were correct. hesselberg led the oceanographic studies and was in charge of the periodical magnetic and hourly meteorological observations. hagen was the man-of-all-work, attending to the instruments, making repairs and doing all kinds of practical jobs. life at the station was necessarily well ordered. the day was divided into four six-hour shifts, except on so-called “term days”, when the instruments had to be observed virtually the whole day through. on term days, which fell on the 1st and 15th of every month, observations were made every five minutes. however, during one hour on each term day, the magnetic observations had to be carried out every 20 seconds. sophus tromholt, a danish auroral scientist who paid a visit to the station in 1882, later remarked: what an endlessness of numbers! at each of the hourly observations, more than one hundred ciphers are noted; thus one normal day represents approximately 2500 ciphers, one term day about 6000. (tromholt 1885: 55; translated by the author) during the first ipy, two official stations were established at the northern cap: the norwegian station at bossekop and the finnish station in sodankylä. tromholt, who was setting up his own auroral observatory, took advantage of the geographical distribution of these stations: a base in kautokeino, situated about 100 km east of bossekop, would make an ideal site for triangulation of the aurora, with the aim of fixing its height (fig. 3). on his own initiative, tromholt set up a network of more than 100 observation posts in norway and other countries, recording regular observations of the aurora. tromholt was convinced that there was a connection between the variations of sunspots and the appearance of aurora. time has proved him right. he is also well known in norway for his ethnographic observations and the many beautiful pictures he took during his stay in kautokeino (fig. 4). norway’s contribution to the second ipy, 1932–33 like the first, the second ipy was a major international programme in geophysics. norway could depend on a relatively strong scientific culture in certain geophysical disciplines. a great deal of norwegian effort had been put into disciplines like meteorology, oceanography and auroral research, with these areas of science becoming the strongholds of norwegian polar research. one of the founding fathers for this geophysical tradition was henrik mohn, who, as described earlier, played a role in bringing the proposal for the first ipy to fruition. mohn was a driving force in many other projects related to norwegian polar research. together with the norwegian marine biologist georg ossian sars, mohn led the second research project in norwegian polar history. this fig. 3 sophus tromholt’s auroral observatory in kautokeino 1882–83. in the middle of the picture you can see the mohn theodolite, which was used in triangulating the position of the aurora. (photo by sophus tromholt, courtesy of the university of bergen library.) 198 polar research 26 2007 195 – 203 © 2007 the author norway and past international polar years s. bones was the vøring expedition, 1876–78, which explored the norwegian sea and, in fact, gave that body of water its name (bjørnsen 2003) (fig. 5). (the first polar expedition sent from norway had been christopher hansteen’s expedition to siberia, 1828–30.) it was mohn who put fridtjof nansen on to the idea of drifting with the sea currents across the arctic ocean. mohn strongly influenced many other norwegian researchers, for instance, the auroral researchers kristian birkeland, carl størmer and lars vegard, the oceanographers bjørn helland-hansen and harald ulrik sverdrup, and the meteorologists vilhelm bjerknes, halvor solberg, theodor hesselberg and jakob bjerknes. both of the two most central people in norway’s second ipy effort, the oceanographer harald ulrik sverdrup and the meteorologist theodor hesselberg, were central in the geophysical research tradition. at the time, sverdrup was at the christian michelsen institute in bergen. sverdrup was elected one of seven members of the international polar commission, led by the renowned director of the danish meteorological institute, dan la cour. in norway, a national committee was put together to coordinate norwegian participation (hesselberg 1932– 33). sverdrup led this norwegian polar committee assisted by theodor hesselberg, the director of the norwegian meteorological institute. (hesselberg held this position from 1915 to 1955. he also served as general secretary of the international meteorological organization from 1923 to 1929, and as its president from 1935 to 1946.) sverdrup was very busy so much of the work of the committee fell to hesselberg, especially in 1931, when sverdrup shouldered responsibility for the scientific work on sir hubert wilkins’s nautilus expedition (fig. 6). carl størmer was another norwegian who took on a special role in the international cooperation during the second ipy. an auroral scientist, he led the international fig. 4 a portrait of two saami: brita olsdatter nango and her child. (photo by sophus tromholt, courtesy of the university of bergen library.) fig. 5 like fridtjof nansen, mohn liked to paint and draw. mohn painted this watercolour of beerenberg, jan mayen, during his expedition in the norwegian sea in 1876–78. (courtesy of the norwegian polar institute picture library.) fig. 6 hubert wilkins (left) and harald ulrik sverdrup on board the submarine nautilus , measuring temperatures deep down in the arctic ocean. (photo by hubert wilkins, courtesy of the norwegian polar institute picture library.) s. bones norway and past international polar years polar research 26 2007 195 – 203 © 2007 the author 199 subcommittee preparing the research in this field. størmer set up much of the plans for the auroral research: he prepared an international auroral atlas with illustrating photographs and descriptions of the different forms of polar lights, and he construed a new camera for photographing the phenomenon. størmer’s camera was in great demand internationally. it was størmer who, based on investigations at bossekop in 1910 and 1913, solved the question of the height of the northern lights through triangulation with his specially adapted camera. in the autumn of 1930, the norwegian polar committee had worked out a programme for the norwegian participation. it suggested that geophysical stations were to be established at the top of the mountain haldde (in the vicinity of bossekop), on the island of bjørnøya, at myggbukta (east greenland), at the top of gaustad (in telemark, southern norway) and at fanaråken (by sognefjord, western norway, 2064 m a.s.l.). according to the plans, several whale processing ships in the southern ocean would also take part. but because of the international economic depression, which also hit norway, the plans had to be somewhat reduced. the committee decided to limit norway’s efforts to broadened activity at the stations and observatories that were already in existence. the committee also decided to invite other nations to travel to norwegian territory to make their ipy observations. the economizing strategy to build on the already existing stations lead the geophysicists to become even more dependent on the milieu around adolf hoel—a research tradition that might be described, in comparison to the “geophysical tradition”, as a more practically oriented “geographical tradition”, leaning heavily on disciplines such as topography and geology. in the period from 1910 to 1940, the geologist adolf hoel was one of the most central polar researchers in norway. from 1928, he led norway’s central state institution for polar research, norges svalbardog ishavsundersøkelser (nsiu; norway’s svalbard and arctic ocean research survey). hoel’s, and the nsiu’s, activities were largely an expression of norwegian territorial expansionism (berg 1995; fure 1996; barr 2003; drivenes 2004; skarstein 2006). although the scientists in the geophysical tradition were seeking to establish, or link themselves to, major scientific programmes— generally international in scope—those in the geographical tradition saw themselves in a national context. the expeditions these scientists undertook were primarily summer expeditions to spitsbergen or greenland—both islands on which norwegian nationalists aimed to make plain the territorial interests of their country (fig. 7). in hoel’s view, history had clearly shown that nations that were able to display the most thoroughly collected scientific knowledge of a “new” territory were able to win most conflicts of interests with other countries (drivenes 1994–95; drivenes 1995). despite the small financial resources allocated for the norwegian ipy activities, contact with hoel and his circle enabled the norwegian polar committee to establish four new stations in east greenland: jonsbu (fig. 8), finnsbu, torgilsbu and storfjord (sverdrup 1932). these were set up as stations for hunters and sealers, but during the ipy they also served as meteorological stations. but for adolf hoel and anders k. orvin, who stood behind the operations in east greenland, the meteorological undertakings were a side issue: the most important motive behind the establishment of these stations was, in fact, territorial expansionism. when john giæver, stationed at jonsbu, received the verdict from the international court in the fig. 7 the norwegian geologist adolf hoel in his office in 1924. the room is dominated by books and annexation signs from spitsbergen, clearly showing hoel’s scientific and political leanings. (courtesy of the norwegian polar institute picture library.) fig. 8 the norwegian station jonsbu, greenland, in march 1933. (photo by john giæver, courtesy of the norwegian polar institute picture library.) 200 polar research 26 2007 195 – 203 © 2007 the author norway and past international polar years s. bones hague that rejected norway’s claim to territory in greenland, he noted forlornly in his diary: “it feels like the bottom has fallen out of our existence here. nothing seems to matter anymore. we are in danish land” (giæver 1932–34; translated by the author). the station at myggbukta was a different story (mikkelsen 2001). it dated back to 1920, when the international commission for weather telegraphy declared that meteorological data from greenland were very important to improve forecasts in europe. ole andreas krogness, the director of the geophysical institute in tromsø, seized on this idea. he contacted sealers bound for east greenland and sent meteorological equipment with them. the meteorological station at myggbukta was established in 1922. during the second ipy, the station at myggbukta contributed meteorological observations and made observations of the aurora. (similar meteorological stations were established at isfjorden, spitsbergen, in 1911, bjørnøya in 1920 and jan mayen in 1921.) the other strategy of the norwegian polar committee was to invite other nations to establish stations on norwegian territory. taking norway up on its offer, sweden established a station on spitsbergen, austria a station on jan mayen, and poland sent an expedition to bjørnøya. several expeditions were also sent to the norwegian mainland, including german and british expeditions to tromsø, where the auroral observatory hosted them. the research carried out by these guest scientists eventually revealed that radiowaves were reflected in the ionosphere, information that proved to be most important during world war ii and afterwards. the leader of the british expedition, sir edward appleton, won a nobel prize in physics in 1947. although the norwegian budget was reduced significantly from what had been initially planned, much important research was carried out during the second ipy. nine whale processing ships in the southern ocean were equipped with meteorological equipment, and the officers on board were trained to make the observations. the results were considered valuable and were published quickly, thanks to a grant of 15 000 kroner from the “whale fund” (aagaard 1934; anonymous 1935a). meteorological data from a network of stations in the arctic had been collected (anonymous 1940). research on terrestrial magnetism had been carried out at the auroral observatory (tromsø), rønvik (bodø), bossekop, dombås and fredrikstad (anonymous 1935b). observations of the aurora had been made in oslo, oscarsborg, kongsberg, tømte, tromsø, tenness, myggbukta, løkken verk and darbu. significant aerological work had also been undertaken, with kjeller and ås as the most important sites. the international geophysical year, 1957–58 in 1957–58, when the international geophysical year (igy) took place, only 12 years had passed since the end of world war ii, yet there had been notable technological advances in that short period of time (international council of scientific unions, international geophysical committee 1959). after the war, many geophysicists were eager to find out how the new technology developed during the war could be used to explore the atmosphere. it was at a private dinner party, with guests including some of the world’s leading geophysicists, that a third polar year was suggested. the suggestion came from the american scientist and engineer lloyd berkner. he emphasized the many technological and scientific advances that had been made since the ipy in the 1930s. he also pointed out that in 1957–58 the sunspot activity would be close to its maximum, whereas in 1932–33 it had been close to its minimum. comparing the results from these two periods would be valuable. constituting a scientific leap for the international research community (sullivan 1962), the igy of 1957–58 is generally considered the third ipy on account of the importance of polar research in the programme and its close connections with previous ipys. the igy lasted from 1 july 1957 to 31 december 1958, but international research efforts were prolonged for one more year: the year of international geophysical cooperation. among the most notable achievements during the igy, both the united states and the soviet union sent out earthorbiting artificial satellites. the soviet union launched the first two: sputnik i, launched on 4 october 1957, and, one month later, sputnik ii. the americans were extremely disturbed by this. as cold war historian walter lafeber has put it, “ ‘gaps’ were suddenly discovered in everything from missile production to the teaching of arithmetic at the preschool level” (lafeber 2002: 203). shocked into action, the usa immediately began work on its own satellite project and, on 31 january 1958, it was able to launch its first earth-orbiting satellite, explorer 1, which revealed the existence of the magnetic radiation belt around the earth, known as the van allen radiation belt. the scientific work carried out during the igy also confirmed the theory of continental drift, a theory first put forward by the german alfred wegener in 1912. another considerable achievement was the first estimates of the total ice mass in antarctica. for norway, antarctica was the most challenging question during the igy. in 1939, norway had annexed a large part of antarctica: dronning maud land. the claim for sovereignty over this area, which demanded a norwegian presence to fend off other claims, was partly motivated by norwegian commercial interests—whaling—and partly s. bones norway and past international polar years polar research 26 2007 195 – 203 © 2007 the author 201 by norwegian territorial expansionism. with norwegian whale catches decreasing after world war ii because of depleted stocks, whaling faded out of the picture, as did one of the motivations for the norwegian claim for sovereignty in antarctica. the other motivation was science, which was also was closely tied up with politics. since the end of the 19th century, norwegian contributions to international polar research had secured the country admission into the exclusive club of polar nations like the uk, sweden, germany and russia. norway was particularly involved in research in svalbard and organized annual expeditions under the nsiu, the forerunner of the norwegian polar institute (npi). one of the reasons why norway was a force to be reckoned with in the polar regions was that neither the arctic nor the antarctic had been seen as strategically important by the great powers. world war ii and the cold war changed that view. as a consequence, norway’s room for manoeuvring both in the north and the south was greatly restricted. norway had to pay close attention to what the influential nations were up to. the founding of npi in 1948 gave a new boost to norwegian polar research. the internationally acknowledged scientist h. u. sverdrup was called home from california to lead the institute (fig. 9). one of his first steps was to organize a very successful expedition to antarctica, the norwegian–british–swedish maudheim expedition (1949–52), led by john giæver (friedman 2006). the maudheim expedition carried out pioneering mapping work in dronning maud land, which strengthened norway’s claim for sovereignty there. after the maudheim expedition, norwegian authorities were more restricted with funding for polar research, and the scientists concentrated their limited resources in the arctic. for the igy in 1957–58, the npi had no plans to conduct research in antarctica. when this became known in october 1954, it led to consternation both in the usa and at the norwegian ministry of foreign affairs (friedman 2006; helsvig 2007). the polar regions were of great strategic importance and the west could not leave a void that could be filled by the soviet union. the norwegian minister of foreign affairs, halvard lange, successfully advocated launching a relatively large norwegian expedition to antarctica during the igy. against this backdrop, the npi equipped the norway station expedition (1956–60), under the leadership of sigurd helle (figs. 10, 11). as with the maudheim expedition, the norway station expedition also expended a great deal of effort in mapping dronning maud land. the expedition made several scientific findings, but even more importantly it manifested norway’s role as a polar nation in the antarctic. in 1957, the international council of scientific unions organized a special committee on antarctic research (scar). (two other permanent scientific committees were also created as a result of the igy: the scientific committee on oceanic research and the committee on space research.) norway, being one of 12 countries in antarctica during the igy, had its own seat in this committee. thanks to the norway station fig. 9 harald ulrik sverdrup as director of the norwegian polar institute. (photo courtesy of the norwegian polar institute picture library.) fig. 10 expedition leader sigurd helle maps dronning maud land, antarctica, during the international geophysical year. (photo by sigurd helle, courtesy of the norwegian polar institute picture library.) 202 polar research 26 2007 195 – 203 © 2007 the author norway and past international polar years s. bones expedition, norway remains a key nation in the administration of the continent. although the norway station expedition was the biggest norwegian effort during the igy, many other scientific contributions were made (orvin 1960). all in all, 25 norwegian stations or projects were involved: three in svalbard, one on jan mayen, one in antarctica, one floating station in the norwegian sea and the rest on the norwegian mainland. the ipy and norway: the politics of science as for the great powers, the igy may stand as a symbol for two different political strategies or tendencies—one focusing on power-oriented manoeuvring, and one oriented towards international cooperation. it is evident that it was equally important for the usa and the soviet union not to let the other side get ahead in any vital field, be it in technological improvements or in strategically important areas. the igy was very much affected by this, as manifested in the sputnik shock (which led to the foundation of the usa’s national aeronutical and space administration). in this competition between the great powers, norway had very little to say, but it was nonetheless important for norway to fly the flag in dronning maud land, just as norway did in svalbard. although the great powers showed some interest in antarctica, the arctic had a much higher priority. later on in the cold war, in 1982, the director of the npi, tore gjelsvik, calculated that the soviet union alone had more than 40 000 people engaged in arctic research and related activities (magnus 1983). in comparison, the current ipy (2007–08) involves the participation of approximately 63 nations and 60 000 people in research and affiliated activities. today’s historical research shows that international contacts forged through the igy contributed to a lasting dialogue that helped ameliorate the antagonism of the cold war (evangelista 1999). in 1959, the 12 nations that were conducting research in the antarctic during the igy became parties to the antarctic treaty. ratified in 1961, the treaty dedicated antarctica to the pursuit of peaceful activities. it established full freedom for all to conduct their research, under the supervision of scar. territorial claims were set aside, or put on ice, so to speak. as we know, science has served various political strategies, in norway as elsewhere. the history of norway’s involvement in the ipy shows that there has been a permanent connection between the scientific and the political spheres in norway. although power politics clearly was part of the picture of the second ipy, it was restrained, and the igy—the third ipy—was largely kept in line with carl weyprecht’s ideals. today, the premises for an even more distanced relation to traditional power politics should be within reach. the challenges are not the same now as they were some 50 years ago (goldman 2007). one might argue that today’s ipy is to a large extent intertwined with a broader, global environmental discourse, a “softer” discourse in which environmental change—particularly climate change—is understood to affect all nations, regardless of their political power, and that international cooperation is the only practical way forward. but at the same time there is undoubtedly a “harder” discourse going on, connected with energy and traditional geopolitics. whether today’s scientists and political leaders manage to merge these two discourses and create a lasting international cooperation in the polar regions remains to be seen. but it would be a vision in line with the history of the ipy. references aagaard b. 1934. fangst og forskning i sydishavet. (hunting and research in the southern ocean.) vol. 3. oslo: gyldendal. anonymous 1935a. meteorological observations made on 9 norwegian whaling floating factories during the international polar year 1932–1933. norwegian publications from the international polar year 1932–33, no. 1 . oslo: grøndahl & søn. anonymous 1935b. work on terrestrial magnetism, aurora and allied phenomena. norwegian publications from the international polar year 1932–33, no. 2 . bergen: a.s john griegs boktrykkeri. anonymous 1940. meteorologische beobachtungen in svalbard radio, bjørnøya, jan mayen, 5 öst-grönländischen stationen und auf dem fanaråken (gipfelstation, 2064 m) während des internationalen polarjahres 1932–33. (meteorological observations from fig. 11 doing his part for the norwegian research effort in antarctica during the international geophysical year, torgny vinje makes scientific observations. (photo by torgny vinje, courtesy of the norwegian polar institute picture library.) s. bones norway and past international polar years polar research 26 2007 195 – 203 © 2007 the author 203 svalbard radio, bjørnøya, jan mayen, 5 stations in east greenland and from fanaråken [top station, 2064 m] during the international polar year, 1932–33.) norwegian publications from the international polar year 1932–33, no. 3 . oslo: grøndahl & søn. baker f. g. w. 1982. the first international polar year, 1882– 83. polar record 21 , 275–285. barr s. 2003. norway—a consistent polar nation? analysis of an image seen through the history of the norwegian polar institute . oslo: kolofon. barr w. 1985. the expeditions of the first international polar year, 1882–83. the arctic institute of north america, technical paper no. 29 . berg r. 1995. norge på egen hånd, 1905–1920. ( norway on her own, 1905–1920 .) oslo: universitetsforlaget. bjørnsen v. 2003. naturvitenskap og politikk. den norske nordhavsekspedisjonen 1876–78. (natural science and politics. the norwegian expedition to the norwegian sea, 1876–78.) ma thesis, university of tromsø. drivenes e.-a. 1992. “la recherche”—forskningsekspedisjonen frankrike glemte. (“la recherche”—the scientific expedition france forgot.) historisk tidsskrift 71 . drivenes e.-a. 1994–95. adolf hoel—polar ideologue and imperialist of the polar sea? acta borealia 11–12 , 63–72. drivenes e.-a. 1995. adolf hoel—ishavsimperialist og polarideolog. (adolf hoel— imperialist of the arctic ocean and polar ideologue.) in r. sørheim & l. j. johannessen (eds.): svalbard—fra ingenmannsland til del av norge. (svalbard—from no-man’s land to a part of norway.) pp. 84–94. trondheim: university of trondheim. drivenes e.-a. 2004. ishavsimperialisme. (arctic ocean imperialism.) in e.-a. drivenes & h. d. jølle (eds.): norsk polarhistorie. (norwegian polar history.) vol. 2. vitenskapene. (the science.) pp. 175–258. oslo: gyldendal. engelbrethsen p. 1895. professor mohn og det norske meteorologiske institutt. (professor mohn and the norwegian meteorological institute.) naturen , 97–104. evangelista m. 1999. unarmed forces. the transnational movement to end the cold war . ithica, ny: cornell university press. friedman r. m. 2006. playing with the big boys. in e.-a. drivenes & h. d. jølle (eds.): into the ice. the history of norway and the polar regions . pp. 319–374. oslo: gyldendal. fure o.-b. 1996. mellomkrigstid, 1920–1940. ( the interwar years, 1920–1940 .) oslo: universitetsforlaget. giæver j. 1932–34. the norwegian polar institute, collection of diaries, no. 82 john giæver: dagbok ført på øst-grønland 1932–1934. (diary written in east greenland, 1932–1934.) goldman h.v. 2007. from the editor: polar research evolves, and norway and the ipy. polar research 26 , 1–6. helsvig k. g. 2007. elitisme på norsk. det norske vitenskapsakademi 1945–2007. (norwegian elitism. the norwegian academy of science and letters, 1945–2007.) oslo: novus forlag. hesselberg t. 1932–33. polaråret. (the polar year.) norsk geografisk tidsskrift 4 , 110–120. international council of scientific unions, international geophysical committee 1959. annals of the international geophysical year 1957–1958. vol. 1. the histories of the international polar years and the inception and development of the international geophysical year . london: pergamon press. knutsen n. m. & posti p. 2002. la recherche. en ekspedisjon mot nord/une expédition vers le nord. (la recherche. an expedition towards the north.) tromsø: angelica forlag as. lafeber w. 2002. america, russia and the cold war, 1945–2000 . new york: mcgraw hill. magnus m. h. 1983. norge og den sovjetiske polarforskning i nord og sør. (norway and the soviet polar research in the north and in the south.) farmand 6 , 84–87. mikkelsen p. s. 2001. nordøst-grønland 1908–60. (north-east greenland.) copenhagen: aschehoug. orvin a. k. 1960. norway’s contributions to the international polar year. the american scandinavian review 48 , 33–41. payer j. 1876. die österreichisch-ungarische nordpol-expedition in den jahren 1872–1874. nebst einer skizze der zweiten deutschen nordpol-expedition 1869–1870 und der polar-expedition von 1871. (the austro-hungarian north pole expedition 1872–1874. also containing a sketch of the german north pole expedition, 1869–1870 and the polar expedition of 1871.) vienna: alfred hölder. skarstein f. 2006. erik the red’s land: the land that never was. polar research 25 , 173–179. steen a. s. 1881. den internationale undersøgelse af polaregnenes fysiske forhold. (the international research on the physical nature of the polar regions.) naturen , 161– 170. sullivan w. 1962. assault on the unkown. the international geophysical year . london: hodder & stoughton ltd. sverdrup h. u. 1932. the national library of norway, special collections, collections of correspondence and letters no. 634 i: harald ulrik sverdrup (1888–1957). file “det internasjonale polaråret 1932/33”. (the international polar year 1932–33.) tromholt s. 1885. under nordlysets straaler. skildringer fra lappernes land. (under the rays of the aurora borealis. descriptions from the land of the saami.) copenhagen: gyldendalske boghandels forlag (f. hegel & søn). occurrence and distribution of king eiders somateria spectabilis and common eiders s. mollissima at disko, west greenland ole fkimer frimer, 0. 1993: occurrence and distribution of king eiders somateria speclabilis and common eiders s . mollissimu at disko, west greenland. polar reseurch i 2 ( 2 ) , 11 1-1 16. king ciders and common eiders were recorded at disko island, west greenland, in the period 1989-1993. both species occur year-round in thc area, although in low numbers during the period of extensive ice cover january-april. in may and the first half of june, large numbers of king and common eiders on spring migration stage along the western coast of disko. in the autumn (august-october) an estimated 1 5 . m 20.100 king eiders undergo prcbasic moult in the area. with the highest concentrations in the fjords and bays of western disko and along the coast of southeast disko. this estimate indicates that a recent population decline may have taken place. only two female common eiders with ducklings were recorded during the study period. in the period july-september an estimated 3 , 2 w , 8 0 0 male common eiders undergo prchasic moult in the area, mainly at the archipelago of kitsissut and in the outer fjords and bays of western disko island. ole frimer. zoologicul museum, universify of copenhagen. universitetsparken is, dk-2100 copenhagen 0? denmark. introduction king eiders somateria spectahilis and common eiders s . mollissima borealis occur commonly in the disko bay region, central west greenland, during the ice-free period (salomonsen 1967). in spring, both eider species pass disko on their way to the breeding grounds (abraham & finney 1986). the common eider breeds in very low numbers on disko island. in july and august the small resident population is accompanied by post breeding male common eiders (frimer i n press), presumably from breeding grounds in west greenland north of disko and/or from northeast canada, who undergo prebasic moult here. between mid-july and early september large numbers of post-breeding king eiders from the eastern and central canadian arctic and north west greenland arrive in the area and undergo prebasic moult here along with a number of imma tures and adult non-breeders which have spent the summer south of the potential breeding range (salomonsen 1968; frimer in press). both eider populations spend the winter in southwest green land (salomonsen 1967, 1968). apart from a few counts of king eiders in aqa jarua, easternmost disko (salomonsen 1967; boertmann 1979), no systematical ground or aerial surveys of eiders have hitherto been made in the area. salomonsen (1968) assumed that some 100,000 king eiders undergo prebasic moult in central west greenland, with the highest con centrations in the disko bay region. in the summer of 1989 i took part in a bird survey on eastern disko island (frimer & nielsen 1990), and in the period june 1990-may 1993 i stayed on disko island. during this period i made systematic and occasional year-round obser vations on the occurrence of eiders at disko. this paper summarizes these observations. , study area and methods observations were made along the entire coast of disko island and at the archipelago of kitsissut in the western disko bay (fig. 1). the sea surrounding disko island is ice-covered from mid-january to mid-april, whereas the fjords and bays may be ice-covered from nov ember to mid or late june. surveys from vessels 112 0. frimer disko island qeqerlarsuaq davis srrair disko bny 69" kilsiss;l% 4% 5 4 " 52' fig. 1. disko island, showing location of places mentioned in the text. * = camp site; = town; 0 = village (bygd) were possible in the western parts of disko from mid-may, while in the northern and eastern parts, surveying was prevented by large amounts of drift ice until early june (early july in some areas). observations were carried out from the arctic stations research vessel porslld and from the coast. a total of about 350 single observations of eiders were made during the study period. the following surveys and observations provide the data for this paper: may-october most western and southern parts of the study area were surveyed 6-10 times during 1990-1992. the northwestern coast was surveyed once each year in august, and the northeastern coast on 24 august 1990. additional observations were car ried out from the coast near the town of qeqer tarsuaq and from camps positioned on western disko between akulliit and kangersooq and at aqajarua, easternmost disko (fig. 1). further details are given together with the results. november-april non-regular , but frequent, observations were made from the coast between ippik and kanger luk. observations were, however, few between late november and mid-january, due to con tinuous darkness. results aqajarua (mudderbugten) on 11 and 12 june 1990, approximately 570 king eiders and 30-35 common eiders were present in the bay. in late june 1989,1990 and 1991, between 200 and 250 king eiders and between 50 and 500 common eiders were counted here each year. in the period july-september 1990,1991 and 1992 a maximum of about 400 eiders (mainly king eiders) were observed in the bay each year. qaamassoq (flakkerhuk) during four surveys carried out between mid june and mid-july 1990, 1991 and 1992, 88-200 eiders were observed along the coast of qaa massoq each year, with about 80% being king eiders. the area was surveyed four times in the moulting season: in late july-early august 1990 and 1991, 3-400 eiders (mainly king eiders) were observed each year; and in early september 1992, a minimum of 3,100 king eiders were present here. on 23 october 1992, i.e., after the moulting season, about 10,ooo king eiders were observed along this coast, in flocks of up to about 3,000 birds. the south coast of disko in spring, flocks of up to about 200 king eiders and 75 common eiders may stage and feed along the coast between qeqertarsuaq and qaamassoq. while later in the season most observed flocks were by-passers. in the period of extensive ice cover, flocks of up to about 25 eiders occasionally occur at temporarily open patches. kitsissut (kronprinsens ejlana's) flocks of common eiders were recorded here on several occasions between mid-may and late august of 1990 and 1991, the maximum number being 350-400 individuals on 11 july 1990. king eiders were seen in numbers of up to about 40 individuals. occurrence and distribution of king eiders 113 in late july 560 king eiders were present in the fjord, and by mid-september numbers had increased to an estimated 2,200-2,400 individual (frimer in press). on 8 august 1991 a flock of more than 200 common eiders was observed in akulliit. in mid august 1992 about 120 common eiders were present at a small bay near the mouth of the fjord, with small flocks elsewhere in the area. the killiit (fortunebay)uiffaq (bldfjeld) coast between mid-may and mid-june 1991 and 1992, 335470 eiders of both species occurred along this coast. on 22 june 1992, about 300 king eiders were observed along uiffaq. between late june and mid-september 1990, 1991 and 1992, a maxi mum of 75 eiders of both species were recorded in the area. a single common eider was observed at killiit i n february. kangerluk (diskofjord) between mid-may and mid-june 1990, 1991 and 19y2, numbers ranging from 500 to 2,500 eiders of both species were recorded along the edge of the fjord ice of kangerluk. on 17 june 1992, a total of about 3,000 eiders (almost exclusively king eiders) were observed here. in early july 1992. about 200 king eiders were recorded at qeqertaq, and about 220 common eiders were observed along the north coast of the outer fjord. small flocks of both species were regularly seen i n the inner fjord in july. in late august 1991, about 500 king eiders were observed in the innermost parts of the fjord, and about 400 king eiders were present at qeqertaq, with several flocks elsewhere in the area. in december 1992 some hundred king eiders were observed along the edge of the fjord ice at the mouth of kangerluk. eqaluit (nordre laksebugt) i n may and early june 1991, up to about 200 eiders were recorded in eqaluit. the area was only visited twice in the moulting season (sep tember 1990 and late july 1991), when a maximum of 35 eiders of both species were observed within the bay, with additional small flocks along the outer coast immediately north and south of the bay. akulliit (mellemfjord) on 17 may approximately 3,000 eiders were observed here, with about 50% being common eiders. numbers decreased gradually during the following month, and on 18 june about 100 eiders of both species were present here. a single female common eider with three duck lings was recorded in early september 1992 in the inner fjord. qasigissat on 19 june 1991 about 700 king eiders were staging along the ice-edge of the bay qasigissat. in early july 1992,160 king eiders and 47 common eiders were counted within the bay. in late july 1990 and 1991, 600-800 moulting common eiders and 70-80 king eiders were present at qasigissat, making qasigissat the most important moulting area for common eiders at disko. in mid-sep tember 1992 at least 500 king eiders were moulting within the bay, with several additional flocks along the outer coast immediately north and south of the bay. kangersooq (nordfjord) on 25 may 1991, a total of 101 king eiders and 16 common eiders were recorded moving north wards 10-25 km offshore, following the edge of the davis strait pack ice. on 20 july 1991, about 300 king eiders and 200 common eiders were present in kangersooq, and on 2 august 1992 about 400 king eiders and 325 common eiders were counted in the fjord. in mid-september 1990 and 1991 more than 1,000 individuals occurred in the inner parts of the fjord, with several flocks elsewhere in the area. northwest disko in late august 1990, about 2,500 eiders (almost exclusively king eiders) were recorded here, while in mid-august 1991 and 1992 only about 200 king eiders were observed along this coastline each year. a female common eider with two newly hatched ducklings was recorded at a coastal lagoon on 18 august 1991. the vaigat coast a total of 200-250 eiders were recorded along this coastline on 24 august 1990. most of these 114 0. frimer birds were moving southwards, suggesting that this area is not used for moulting by large numbers of eiders. sex ratios the sex ratio of king and common eiders was recorded in a number of sample flocks during the study period. of 383 king eiders sexed in may and june, 48% were females. the sex ratio in king eiders at disko, during the period july september, has been treated in frimer (in press): females made up an estimated 33% of the popu lation in july, 24% in mid-august and 48% in mid-september. of 122 common eiders sexed between early may and mid-june, 39% were females. in the breeding season, mid-june-august, females com prised less than 1 % of the recorded common eiders (see also frimer & nielsen 1990; frimer in press). no observations on the sex ratio of com mon eiders were made after august. discussion the spring migration both eider species arrive at disko from mid april, when the sea ice breaks up. in may and the first half of june, large numbers of king and common eiders on spring migration stage at the ice-edge of the fjords and bays of western disko island; for example, on 17 may 1991 a total of about 6,000 eiders were counted between killiit and akulliit. by mid-june the majority of the eiders have left the area, the common eiders apparently about a week earlier than the king eiders. the moult migration less than a month after the last pre-breeding king eiders have left disko, the first post-breeders return to the area to undergo prebasic moult here. the males arrive between mid-july and mid august, and the females between mid-august and early september (salomonsen 1968; frimer in press). consequently, the male : female ratio in king eiders shifts from about 1 : 1 in spring, t o about 3 : 1 in mid-august, and back to about 1 : 1 in mid-september. considering that only two female common eiders with ducklings were recorded in the study period, most of the comparatively large numbers of males present in the area from july are prob ably post-breeders from breeding grounds in west greenland north of disko and/or from northeast canada (see salomonsen 1967; abraham & fin ney 1986). the low proportion of female common eiders present in the area in the breeding season indicates that immature and non-breeding female common eiders do not use the disko bay area for moulting, unlike those of king eiders (frimer in press). autumn distribution and population sizes the most important moulting areas for king eiders were found to be the fjords and bays of western disko and along the coast of qaamassoq (fig. 2a), but small groups and single individuals may occur anywhere along the coasts of disko island in the moulting season. the highest concen trations of moulting common eiders were rec orded at the archipelago of kitsissut and in the outer bays and fjords of western disko (fig. 2b). based on numbers recorded in the study area in the summer and autumn of the years 1990 1992, the total autumn populations of king eiders (september) and male common eiders (july august) at disko are estimated to be 15,400 20,100 and 3,2004,800 individuals, respectively (table 1). as no data on the sex ratio of common eiders is available after august, it is not known whether post-breeding female common eiders from breeding grounds outside the study area undergo prebasic moult at disko. although the timing of moult in both species varies with sex and age (cramp & simmons 1977; frimer in press), the population turnover of eiders in the moulting season is probably low, because the majority of the eiders do not leave the area until some time after the period of prebasic moult (salomonsen 1967). judged from the few obser vations made in the late autumn, after the period of prebasic moult, eiders congregate at the mouth of the fjords when these become ice-covered, and particularly in the eastern disko bay. there is no doubt that the summer and autumn population of king eiders at disko is not as numerous at present as in the 1960s and 1970s. in aqajarua, boertmann (1979) counted 2,800 king eiders in june 1975 and 2,500 in july 1976, and salomonsen (1967) reported about 30,000 king eiders at aqajarua in august. occurrence and dktribution of king eiders 115 a ’?$ b fig. 2. important moulting areas for king eiders ( a ) and common cidcrs ( b ) at disko. based on obscrvations made during 19% 1992. king eiders shed their flight feathers simul taneously and become flightless for about three weeks (salomonsen 1990). in this period they become extremely shy and highly vulnerable to predation. at disko, moulting king eiders feed primarily on soft bottom molluscs, with mya trun cata, serripes groenlandicus and cardium ciliatum together comprising more than 80% of the diet by wet weight (frimer in press). in recent years, trawlers from the town of ilulissat, situated at the eastern disko bay, have been dredging clams chlamys islandicus in aqajarua in t h e summer and autumn. t h e consequent damage to the bot tom fauna and the disturbance caused by these trawlers may explain the low numbers of king eiders in aqajarua in this study. whether the reduced numbers reflect a decline in the popu lation as a whole o r only a redistribution is open to dispute. no attempts have been made to esti mate the king eider population(s) in question tahlc i . estimated nunihcrs o f king eiders and male common eiders moulting at disko; based on observations made during 19%& 1992. locality king eidcr (september) common cider (july-august) comments aqajarua qaamassoq south coast kitsissut killiit-uiffaq kangerluk eqaluit akulliit qasigissat kangcrsooq nw coast vaigat coast total assumed including outer coastal area including outer coastal area including outer coastal area including outer coastal area common eiders assumed assumed 116 0. frirner (abraham & finney 1986), and the overall popu lation trends are unknown. aerial surveys cover ing the entire disko bay region should be made to obtain a more complete picture of the autumn distribution of eiders in the region. the surveys should be carried out in early september, when the moult migration of king eiders cease. acknowledgemenu. i wish to thank the crew of the arctic station's research vessel porsild. h.-e. jensen took part in the field work in the summer of 1991 and t . k. christensen in the autumn of 1992; h. jenscn. e. knudscn. b. mortcnsen. s. m. nielsen, l. skytte and f. steffens provided information on eiders, my thanks are due to them all. j . fjeldsp and two anonymous referees arc thanked for criticism of the manuscript, and r. m. kristensen for various kinds of help. the study was supported financially by the commission for scientific research in greenland (grant no. 5.111/23 0.234-91) and the danish natural science research council (grant no. 11-8974). references abraham, k. f. & finney, g . h . 19x6: eiders of thc eastern canadian arctic. pp. 55-73 in reed, a . (ed.): eider ducks in canada. canadian wildlife service rep. ser. no. 46. ottawa. boertmann, d. 1979: (ornithological observations i n west greenland, 1972-77). dansk om. foren. tidsskr. 73. 171 176. (english summary). cramp, s. & simmons, k. e. l. (cds.) 1977: handbook of the birds of europe, the middle east. and north africa: the birds of the western palearctic. vol. i . oxford university press, oxford and new york. 722 pp. frimer. 0. in press: autumn arrival and moult in king eiders somuteria spectabilis at disko. wcst grccnland. arctic. frimer. 0. & nielsen, s . m. 1990: bird observations in aqaj arua-sullorsuaq, disko. west greenland. 1989. dunsk o m . foren. tidsskr. 84. 151-158. salomonsen. f. 1967: fuglene p i gr@nland. rhodos. k ~ b e n havn. 341 pp. salomonsen, f. 1968: the moult migration. wildfowl 19.5-24. salomonsen, f. (ed.) 1990: grmnlands fauna. (2nd ed.). gyl dendal. k ~ b e n h a v n . 464 pp. calanus in north norwegian fjords and in the barents sea kurt s. tande k. s. tande. 1989: calanus in north norwegian fjords and in the barcnts sea. pp. 38y-407 in sakshaug. e.. hopkins. c. c. e. & 0ritsland. n. a . (eds.): proceedings of the pro mare symposium o n polar marine ecology. trondheim. 12-16 may 1990. polar research lo(,?). the physical environment of a north norwegian fjord and of the atlantic and arctic domains of the barcnts sea are described. the seasonal variation of primary production and biomass of thc most important copepod species are dcscribed in order to contrast regional differences in the timing of the plankton cyclo. analysis of the seasonal variation in the biomass of six different copepod species in balsfjordcn clearly demonstrate the importance of calanus finmarchicus as a spring and early summer form, whereas pseu doculanus acuspes. the most important smaller form. rcachcs the highest biomass later during the productivc season. in the atlantic part of the barents sea. c. finmarchicur is the dominant herbivorous form. the next most important species, pseudocalanus sp. and m . longa. play a less important role here than i n balsfjorden. i n the arctic domain, the smaller copepod forms appear to have bccn replaced in tro phodynamic terms by the youngest year-group (c-chi) of c . glacialis. which prevails during the arctic summer and autumn periods. the coupling between primary producers and calmus on a seasonal basis is addressed through the grazing and the vertical organisation of the plant-herbivore community. the productivity of thcsc two calanus species is considered in relation to the scasonal and inter-annual variation in climate; although different mechanisms are utilised. cold periods tend to lowcr culunus productivity both in the arctic and the atlantic domains of the barents sea. interannual variations in calatrus biomass and productivity are discussed in the perspective of endcmic and advective processes. kurt s. tande. department of aquatic biology. norwegian college of fishery science. university of tromso. n-9001 tromsm, norwuy introduction the ecology of the north atlantic has been inten sively studied for several decades. the majority of the studies have concentrated on the eastern region, with most effort probably concentrated on the north sea, the norwegian sea, and the adjacent continental shelf. the norwegian atlantic current transports atlantic water north eastwards, thereby creating a marine environ mental continuum which extends to the barents sea and further northwards to the western coast of svalbard (blindheim & loeng 1981). with these fairly homogeneous physical environmental conditions we would expect to find a plankton community which is structured and functions basi cally in the same way throughout the entire area. in this study the physical environments of a north norwegian fjord and the atlantic and arctic domains in the barents sea are described. the seasonal variation of primary production and bio mass of the most important copepod species are also described in order to contrast any regional differences in the timing of the plankton cycles. species succession in the phytoplankton and cope pod communities is described in order to charac terise differences among the pelagic communities from neritic coastal waters in northern norway, the atlantic waters of the barents sea, and the arctic portion of the barents sea. the species composition and seasonal growth cycles of herbivorous copepods have been described in the norwegian fjords by hopkins et al. (1984,1985). the most abundant herbivorous copepod species belong to the genus calanus, and calanus finmarchicus should be considered the key species throughout the area of atlantic waters (matthews 1967; jaschnov 1970, 1972). the geo graphical range of c. hyperboreus and c. glacialis is related to different water masses which link the former to deep water masses in the norwegian sea and to arctic waters in the northern hemi sphere (jaschnov 1967). the only true arctic species, c. glacialis, is consistently present in waters north of the polar front. this paper pre sents data for seasonal biomass cycles of the most important copepods in the region, with special 390 k . s. tande a 7 0" fig. 1. surface currents in the norwegian sea. the barents sea. and in coastal waters of northern norway (a); topography in fjords around tromse ( b ) and in the barents sea (c). broken line = mean position of the polar front. sd 7 5( 7 0' emphasis on c. finniarchicirs and c. glacialis in the barents sea ecosystem. climatic changes could modify the productivity of these two species. i attempt t o explain the biological basis behind such a possible modification. t h e tropho dynamic role of calanus and the vertical organ isation of the plant-herbivore relationship are discussed. based o n data obtained mainly during the pro mare programme. the physical environment the seasonal and interannual variations in the physical environment in coastal waters of north ern norway and in the barents sea are to a large extent driven by processes in the oceanic north atlantic (cushing & dixon 1976). the north atlantic current enters the norwegian sea mainly through the faroe-shetland channel. before it reaches the norwegian continental shelf between 62 and 63"n, a branch diverts into t h e north sea along the western and southern slopes of t h e norwegian channel (blindheim & loeng 1981). the bulk of the atlantic w a t e r flows northwards and splits in two branches off the coast of troms, in northern norway. o n e branch continues north wards as the west spitsbergen c u r r e n t , and the calanus in north norwegian fjords and in the barents sea 391 other is diverted into the barents sea as the north cape current. north norwegian f o r d s the atlantic water is, to a certain extent, isolated from the coast of norway by the norwegian coastal current. freshwater from the baltic cur rent mixes with north sea and atlantic waters to form the northward flowing norwegian coastal current. light coastal water spreads out in a wedge form above the heavier atlantic water. the seaward extent of this wedge of coastal water varies seasonally and reaches its maximum in winter. along the norwegian coast there is a further supply of freshwater runoff, but in spite of this there is an increase in salinity towards the north which is due t o mixing with atlantic water. although balsfjorden (69"n; 19"e) is generally a cold fjord, the physical environment is con sidered to be representative of north norwegian fjords (fig. 1). the general topography, seasonal temperature variation, salinity, and stability are described in eilertsen et al. (1981). these fjords have from one to several basins with a maximum depth of ca. 200 m. the temperature varies from about 1 to 7"c, and the salinity ranges from ca. 32.80 to 34.00 during most of the year. barents sea the coastal current enters the southeastern region of the barents sea. the southern part of the atlantic current continues eastward together with the norwegian coastal current and proceeds along the murman coast as the murman current (midttun & loeng 1987). a northern part (north cape current) transports atlantic water into the barents sea along the channel, bjorn~yrenna. the influx of arctic water to the barents sea takes place along two main openings between frans josef land and novaja zemlja (dickson et al. 1970). the area where the atlantic and the arctic water masses meet is called the polar front. in the area west of sentralbanken, the polar front is sharp and shows features typical of the bottom topography. in the eastern barents sea, the frontal area is less distinct, and mixed water masses cover large areas (c.f. fig. 1). atlantic water masses are, in general, defined by salinities of >35.00 (helland-hansen & nan sen 1909). at the entrance to the barents sea, the mean salinity and temperature in the core during the period 1967-1977 were 35.13 and 6.2"c, respectively (blindheim & loeng 1981). further east, the characteristic change t o lower salinity and temperature has been demonstrated by loeng & midttun (1984). arctic water, or the barents sea winter water, is mainly found in the intermediate layer (from 20 to 150 m) in the northern barents sea. the core is usually found between depths of 30-60m with a temperature below -1.5"c and a salinity between 34.4 and 34.6 (midttun & loeng 1987). seasonal variations in the position of the ice border are, in general, similar from year to year with maximum and minimum extension in march may and august-september (loeng & vinje 1979). ice formation usually starts in late sep tember or october, and the ice border moves rapidly southwards to the polar front during nov ember and december. the retreat of the ice starts in may. in the beginning, the rate of melting is slow, but it increases and reaches its maximum in july and early august. considerable interannual variations in sea ice extension occur and variations within the extremes can exceed 500 km, especially in summer and autumn. large variations in the temperature of the atlantic waters have been observed which indicate variability in the inflow and/or cooling of these water masses (adlandsvik 1989). a more comprehensive description of the physical environment in the barents sea is given in loeng (1991 this volume). the biological environment primary production in balsfjorden, in northern norway, the light regime varies considerably on a seasonal basis, with negligible or immeasurable light in decem ber and january (eilertsen & taasen 1984). the sun stays below the horizon from 26 november until 18 january and is continuously above the horizon during the period of midnight sun from 28 may to 19 july. at the end of march mean daily radiation is more than 200 ly d-l until the end of august. the primary production period starts in march, reaching a maximum of ca. 650mg c d-' in mid-april, followed by a cul mination period in may (eilertsen & taasen 1984). a subsidiary peak in production, although not necessarily a yearly phenomenon, occurs dur ing august and september through stability 392 k . s . tande deformation in surface waters (eilertsen 1983: eilertsen & taasen 1984). integrated annual pri mary production for the years 197&1978 is ca. 120 g c m-:. in the barents sea, physical conditions may b e very different from o n e area to a n o t h e r , mainly because ice tends t o reduce atmospheric influ ences on the water masses. additional variability is enforced by bottom topography, currents. and differences in the physical conditions of the sea water. spring phytoplankton blooms are the result of light intensity at a particular depth and the rate of vertical mixing of the water column water column stabilisation is necessary for the onset and development of any high latitude spring bloom (sverdrup 1953; sambrotto e t al. 1986). two different sets of conditions. although not mandatory for the onset of the spring bloom. could exist during spring in t h e barents sea. first, when the ice extends t o the south of the polar front. atlantic water could initiate the melting of ice early in the spring, d u e to its relatively high water temperatures. this would, in principle, have the same effect as the melting period d u e t o increased solar radiation which would normally take place at a later period in t r u e arctic water. such melting enhances stability, and favours an intense spring phytoplankton bloom (see fig. 7 ) second, the oceanic waters not influenced by ice formation are most frequently found in the atlan tic domain. t h e yearly build-up of the ther mocline in these waters takes place in j u n e , generally with low stability of t h e water masses throughout april and may (skjoldal e t al. 1987). this would tend t o shift the culmination of the phytoplankton bloom towards the end of may and the beginning of j u n e , although a substantial primary production has taken place during april and may. using model simulations. the annual primary production has been estimated t o be ca. 70 g c m-? y r ' and 55 g c m-' y r ' in the atlan tic and arctic domains, respectively (slagstad & tande 1990: tande & slagstad 1991) information from field investigations in the barents sea indicates that the spring phy toplankton bloom is initiated in april in unstrati fied atlantic water masses (skjoldal et al. 1987; eilertsen et al. 1989). in the fjords of the western coast of svalbard, a t a latitude of 8-10' further north, the spring bloom was shown t o start at approximately the same time as the spring bloom in the coastal areas of northern norway (eilertsen et al. 1989). it is noteworthy that the spring bloom in the balsfjorden area and in t h e atlantic water of the barents sea occurs in unstratified water masses. this means that t h e rate of vertical mixing in these areas allows for net phytoplankton pro duction before any of the conventional physical criteria show any density gradient. eilertsen e t al. (1989) draw attention t o the fact that after t h e vernal equinox (21 march) the day-length increases at a faster rate at high latitudes, and that this rapid increase in day-length enhances primary production when compared t o areas further south. they conclude that the critical depth is deeper in northern areas, since the days are longer further north and the global radiation values are comparable between, for instance, 70 and 78"n from march to may. t h u s , stratification of the water masses in t h e barents sea tends t o fix the time of culmination rather than t h e onset of the spring phytoplankton bloom in t h e atlantic water of the barents sea. composition of phytoplankton species in fjord areas in northern norway flagellates of size <5 pm prevail regularly during t h e pre-bloom period in march (eilertsen pers. commun.), whereas the diatoms chaetoceros socialis, nitz schia grunowii, thalassiosira gravidalrotula, t . nordenskioeldii, and the prymnesiophyte, phae ocvstis pouchetii, constituted the bloom in april and may. t h e proportion of diatoms and p . p o u chetii in the phytoplankton during t h e spring bloom shows a shift toward a predominance of p . pouchetii during may a n d j u n e (eilertsen e t al. 1981; eilertsen & taasen 1984). during t h e autumn. small amounts of p. pouchetii were present together with t h e coccolithophorides anthosphera robusta and emiliania huxley, as well as small amounts of diatoms and dino flagellates. d a t a from trondheimsfjorden (63"n) in the south t o ullsfjorden (69") in the north show that the species chaeotoceros socialis, phaeocystis pouchetii, and skeletonema costaturn a r e common components of t h e spring phytoplankton in five different localities along t h e coast ( g a a r d e r 1938; sakshaug 1972: h e i m d a l l 9 7 4 ; schei 1974; eilert sen et al. 1981). eilertsen e t al. (1981) attribute this similarity among t h e dominant species t o t h e estuarine circulation which prevails between the fjords and the norwegian coastal current. a correspondingly detailed description of the seasonal succession in phytoplankton species calanus in north norwegian fiords and in the barents sea 393 composition in the atlantic and arctic waters of the barents sea is unavailable. nevertheless, diatoms of the genera chaetoceros, thalassiosira, and nitzschia, and the prymnesiophyte phae oecystis pouchetii, are the most important species in these waters. the species succession during the spring and early summer period tend to show the same pattern as found in coastal waters in northern norway (eilertsen pers. comm.). blooms associated with the ice edge tend to be characterised by slightly different floral assem blages, both in atlantic and arctic waters. the under-ice phytoplankton species melosira arctica, thalassiosira bioculata, and actinocyclus sp. pre vail in multiand two-year-old ice, whereas the pennate diatoms navicula vanhoeffeni and nitz chia frigida are found primarily under one-year oldice (nost-hegseth, pers. commun.). although blooms of these species are associated with the under ice surface, thalassiosira spp. can be found as important members during the spring bloom in pelagic waters during the retreat of the ice edge. regional differences in the copepod community in balsfjorden, in northern norway, the total copepod biomass in 1977 was in general low dur ing winter and spring, and the maximum appeared late in the summer (fig. 2). compared to more oceanic environments, for example the ocean weather station i (osw i ) in the north atlantic, a two-fold higher annual primary production in balsfjorden translates into higher overall standing balsfjorden l o o r 0-0 primary production 1 6 0 stocks of copepods, with mean monthly averages of 24mg wet weight m-) at osw i (parsons & lalli 1988, fig. 7) and 18mg dry weight m j in balsfjorden (fig. 2). primary production and copepod production, reflected in biomass build up, appears to be more closely coupled in the north atlantic than in balsfjorden. peaks in phy toplankton production and zooplankton biomass at osw i were in june, while in balsfjorden the peaks were in april and in the autumn. this is, in general, considered to be a combined effect of differences in temperature, species composition. and life cycle patterns of the species involved in these two environments. detailed descriptions of the zooplankton com munity in balsfjorden, based on data obtained during the second half of the 1970s, have been given by tande (1982) and hopkins et al. (1984). six different copepod species occur regularly throughout the year in this fjord (fig. 3). among the smaller forms are the calanoid microcafanus pusillus and the cyclopoid oithona sirnilis. species of intermediate size (adult size < 1.5 mm in pro some length) are acartia longiremis and pseu docalanus acuspes. metridia longa and calanus finmarchicus are the larger copepods in the fjord. occasionally, c . hyperboreus, ternora longi cornis, and euchaeta norvegica are recorded in the fjord and are possibly associated with the inflow of oceanic waters in the coastal current. population data were obtained from balsfjorden for m. longa via sampling once or twice a month during 1978 (granvik & hopkins 1984) and monthly for all the other species during 1977. 10 fig. 3. seasonal variation in biomass for the copepods calanus finmarchicus (cfin). merridia longa ( m e t ) . t'seudocalanus acuspes (pseu). acarria longeremis ( a c a r ) , oirhono sitnilis (oith), and microcalanus pusillus (micr) in balsfjorden. time fig. 2. seasonal variation in primary production and copepod biomassin balsfjorden, northern norway, in 1977. the primary production data are adopted from eilertsen & taasen (1984). 394 k. s. tande copepod biomass calculations of the biomass are based on dry weight data from various sources. adult dry weights of microcalanus pusillus of 5.7 yg and a mean dry weight of 1.6 yg for ci-cv are cal culated from data given in davis (1984). assuming 40% of the dry weight as carbon content. the cyclopoid copepod oithona similis is converted to biomass by assuming a mean dry weight of 1 yg (civ) and 2.2 ygforcopepodite stages and adults, respectively. data for adults are given by evans (1977), and the dry weight for civ is calculated assuming a 50%) weight increment per stage (see mclaren et al. 1989). adult dry weights of 6 yg have been obtained for acartia longiremis from waters around t r o m s ~ (norrbin et al. 1990). car bon contents for copepodite stages are given by berggreen et al. (1988) and have been converted to dry weights assuming a dry weight carbon content of 40%. taking a dry weight of 10 pg for cv and adult pseudocalanus acuspes (norrbin et al. 1990), dry weights for the other copepodite stages were calculated using a weight increment of 50% per stage (see davis 1984; klein breteler et al. 1982). the seasonal variation in dry weights and civ, cv, and adult calanus finmarchicus, and of cv and adult metridia longa are given i n tande (1982) and grenvik & hopkins (1984). for ci-chi c.finmarchicus, dry weights obtained i n t h e barents sea were adopted in the present calculation (tande & slagstad 1991). for cope podite stages i-iv of m . longa, the dry weights have been calculated by converting the dry weights from corresponding stages of c . fin marchicus using a dry weight factor (0.4) between cv and adult females obtained from these two species in balsfjorden (tande 1982). minimum standing stocks in terms of dry weight were found during the winter for all of the species listed. the most dramatic changes were found in acartia longiremis, which was virtually absent during the overwintering period (fig. 3). a dra matic decline in c. finmarchicus stock is associ ated with the period of reproduction in march and april. the two more herbivorous species. c . finmarchicus and p. acuspes, rely to a greater extent on wax esters during the winter period (norrbin et al. 1990) and commence spawning at the beginning of the spring bloom at the end of march (die1 & tande 1991). the more omnivor ous copepod species. metridia longa, for which the intake of energy is essential during the winter season, spawns at the end of the spring bloom in may (tande & grenvik 1983), whereas the increase in the biomass of a . longiremis in may and june is probably due more to the hatching of resting eggs produced the year before (pertzova 1974; lindley 1990). clearly c . finmarchicus dominates during spring and early summer, whereas the smaller form, p. acuspes, reaches the highest biomass later in the productive season (fig. 3). although the variation in the biomass during the season could be partly due to advection into the fjord, the general picture of a separation in time between these two species is expected according to the generation pattern. the annual generation of c . finmarchicus produced from april to june shows an increase in production at the subsidiary peak in primary production during august and september which is usually found in these waters (tande 1982). p . acuspes is represented by two or possibly three generations in this fjord (norrbin 1987), giving rise to a build up in biomass in late summer and autumn (fig. 3). a corresponding list of copepod species can be constructed for both the atlantic and the arctic domains in the barents sea. based on abundances - w met mlcr 72 73 7 4 75 75.5 76 77 7a 79 latitude (" n) atlantic arctic polar front fig. 4 rcgional variations in biomass of the most quantitative important copcpods during the summer and autumn of 19x1 in thc barenls sea. symbols as in fig. 3 . rcdrawn from ilassel ( 1 yr6). calanus in north norwegian fiords and in the barents sea 395 published by hassel(l986), biomasses have been calculated for the numerically most important copepods in the arctic and atlantic domains dur ing the summer of 1981 (fig. 4). data were selec ted from two cruises on a transect covering 73”oo’n t o 75’59” and 75’30” t o 78”50‘n, from 27-28 june and 8-10 august, respectively (see fig. 1). an abundance of data was converted to biomass data using the same stage-specific dry weights given above. the abundance of calanus was not separated at the species level in the inves tigation, but hassel(l986) found that the majority of calanus spp. to the north of the polar front belonged to c. glacialis, whereas c. finmarchicus prevailed in atlantic waters. in order to empha sise the differences in the copepod community across the polar front, the abundance of calanus spp. given in june and august 1981 has conse quently been converted to biomass data. this was done by adopting dry weights of c. finmarchicus and c. glacialis for the cruises in june and august, respectively. at 76”n where the two lags over lapped, the biomass of calanus is given as the sum of the biomass calculated in june as c . fin marchicus and in august as c. glacialis. dry weights for c. glacialis (copepodite stages and adults) and for c. finmarchicus are based on data from slagstad & tande (1990) and tande & slag stad (1991), respectively. the largest copepodite stages and adults of c. glacialis were not quantitatively sampled by a 36-cm diameter juday net with 180pm mesh. nevertheless, the overall changes in the pro portion of the biomass between the species mir rors important differences in the copepod community across the polar front in the barents sea. compared to balsfjorden, however, there are definite changes in the proportions and the potential quantitative importance among the species. in general terms, c. finmarchicus appears to have attained a more central position in atlan tic waters than in the coastal areas in northern norway, with biomasses of ca. 70 mg dw rne3 at 73”n in june. a reduced quantitative importance of the smaller copepod forms is also apparent, especially in the arctic water. the biomass of the arctic species c. glacialis increases at increasing distances from the polar front, attaining a maxi mum of ca. 30mg dw m-3 at 79’”. from the current data these two calanus species appear in low biomasses in the region of the polar front, but further data analysis and investigations are required to substantiate this pattern. the transect in august coincides with the end of the productive period, both in the most north ernmost areas in the atlantic domain and in true arctic water at 79”n. the more neritic species, such as acartia longiremis, are recorded only occasionally in the barents sea (norrbin pers. commun.) and are of minor quantitative import ance. the other copepod species, microcalanus pusillus, oithona similis, pseudocalanus spp. and metridia longa, are found in lower biomasses in the barents sea as compared to balsfjorden dur ing the autumn. the two latter forms are listed as the most abundant copepods next to calanus in the barents sea (skjoldal et al. 1987), but the data from 1981 indicate that both pseudoca1anu.s spp. and m . longa play a less important tro phodynamic role in the barents sea ecosystem compared to balsfjorden. the biomass data show a maximum of pseudocalanus spp. and 0. similis in the polar front region, reflecting the annual build-up of these populations in atlantic waters analogous to that found in balsfjorden during the autumn. a large abundance of ci-ciii shows that m . longa would also have an equivalent potential (hassel 1986), but this is not seen in the biomass build-up which is anticipated to take place later in the autumn when civ, cv, and adults appear in the population (see tande & granvik 1983). the smallest copepod species, m . pusillus, increases in biomass at increasing distance to the north of the polar front. although biomass values are low, the species should be considered impor tant in trophodynamic terms due to its numerical dominance in the arctic waters of the barents sea. culunus: species distribution in the barents sea the three species in the genus calanus occur regularly in the barents sea. although c. f i n marchicus is considered to be atlantic, it gen erally occurs near the polar front (fig. 5). depth integrated biomasses (0-100 m) of adult female c. finmarchicus and c . glacialis given as means from four different stations obtained during a cruise with r. v . andenes 19 and 20 april 1986 in the same region revealed that the standing stock of adults was 132 and 96 mg c m-*, respect ively. maturity analyses (unpubl. data) confirm that both species had already started spawning in this region as early as mid-april. this is consistent 396 k. s. tande 80 7 5 7c 80 7 5 7 3 20" 30" 40" 17-23 july 1987 '"\ i 70" 20" 30' 40" 20' 30' 40' fig. 5 . dcpth intcgratcd biomass (0-100 m) for three species in the genus culaiiiis. c. finmarchicus. c. ,yluciulis and c. h,vprrhoreirs. 'from three periods in 1986 (a). 1987 ( b ) . and lyx1 ( c ) . calanus in north norwegian fjords and in the barents sea 397 with observations for c . glacialis from the fram strait which showed pre bloom spawning at chlorophyll concentrations <0.1 mg m-3 at the end of march (smith 1990). in july 1987, although the civ and cv dom inated the biomass (fig. 5b), ci-ciii was clearly the most abundant stages (see hansen et al. 1990). using depth-integrated carbon from the surface to 100 m, the biomass data were calculated from abundance data and stage specific carbon content for c . hyperboreus, c . finmarchicus and c . gla cialis as given in hansen et al. (1990), slagstad & tande (1990), and tande & slagstad (1991), respectively. the size frequency distributions of the ci-ciii copepodites did not show any clear species separation (see also hansen et al. 1990, fig. 2). however, in c . glacialis civ-adults pre vailed both in abundance and biomass at stations 1 and 3, while c. finmarchicus was found with the highest biomass at station 2. at this time, c . hyperboreus was present as civ, cv, and adult females at biomass <75 mg c m-* in these waters. in arctic waters at 77 and 82"n (fig. 5c), c. glacialis prevailed, supporting the idea that this is a true arctic species (jaschnov 1972; tande et al. 1985). depth-integrated biomass from depths of 20 to 80 m have been obtained from an inves tigation conducted on 25 july (station 1) and 27 28 july (station 2) by r. v. lance in 1984. the investigation is described in detail in eilertsen et al. (1989). due to high abundances of ci-ciii at both stations, the biomass of these stages exceeded the sum of the other copepodite stages and adults. although ci-ciii were present for c . hyperboreus, the majority of biomass in this species was found as civ, cv, and adult females. at stations 1 and 2 this species was found with biomasses of 764 and 1297mg c m-2, respect ively, which are probably underestimates but sub stantially above the values described for the polar front (fig. 5a and b). the data indicate that the importance of c . hyperboreus in terms of biomass appears to increase with latitude in the barents sea, at least in certain years and regions. data from the fram strait indicate also that the species is found at higher biomasses in arctic water than in atlantic water (barthell988; diel 1989). this has, among other things, led to the theory that this species is arctic (conover 1988). however, the high bio masses generally found in the arctic could equally well reflect low predation rates and hence increased longevity as compared to the atlantic. the species is widely distributed and commonly found, although not reproducing, on the western coast of norway (matthews et al. 1978). this emphasises that c . hyperboreus is the most cosmopolitan of the three species in the calanlts complex, with an atlantic population base depen dent on deep waters for maintaining a successful life cycle. the other two species of calanus occupy the two different domains i n the barents sea which coexist in the polar front region. the interchange of these two species north of the polar front depends on the rate of exchange of atlantic and arctic waters and on the balance between recruit ment and mortality in the two populations. from what has been outlined above, i will in the fol lowing describe how c . finmarchicus and c . gla cialis function in trophodynamic terms in the atlantic and arctic regions, respectively. the objective will be to delineate how climatic changes in the region could alter the potential productivity of these two species and thereby influence the rate of energy flow within the pelagic food web in the barents sea. calanus glacialis generation pattern and biomass although a two year generation cycle has been suggested for calanus glacialis in the barents sea (prygunkova 1968; naumenko 1979; tande et al. 1985; slagstad & tande 1990), an annual life cycle has been suggested for populations off south western nova scotia (runge et al. 1986), for the inner godthlb fjord (maclellan 1967), fram strait (smith 1990), and for the davis strait (huntley et al. 1983). the presence of ci-ciii c . glacialis during the productive season, with notable maximum abundances from mid-june to mid-august, is a consistent feature in the arctic (grainger 1961; maclellan 1967; diel 1989; eilertsen et al. 1989; hansen et al. 1990). a flexible spawning behaviour pattern for c. gla cialis is attained by long-term preservation of its reproductive potential, rapid mobilisation of ovaries during periods of favorable food conditions, and high rates of egg production (hir che & bohrer 1987; hirche 1989). although c. glacialis has been considered to spawn during the arctic spring bloom, smith (1990) showed that food was not required for spawning in the fram 398 k . s . tande strait in late march and early april. cohorts produced during spawning in april would favour a generation time of o n e year, although spawning in may and june would be more suitable for a two-year life span (slagstad & t a n d e 1990). spawning, and the subsequent development of recruits in august and september, allows a fairly low chance of building u p energy reserves for survival through the overwintering period; these recruits are likely to be considered as pseu docohorts (see hirche 1989). c a r e should be taken when estimating the length of the life cycle based on embryonic development and the pos tulated rule of equiproportional development (see corkett e t al. 1986; t a n d e 1988a; smith 1990; pedersen & tande 1991). however, the lack of frequent sampling o n a seasonal basis of c . gla cialis restricts o u r chances of tracing the periods of diapause, which should give two major over wintering stages (civ and c v ) in a two-year life cycle. although the available data give n o conclusive evidence for either an annual or a biennal life cycle, it could well be that the above reports mirror a flexible life cycle, where the circulation pattern. the extent of the productive period. and the timing of spawning determine the fraction of the population which enter a two-year life cycle. a generally higher standing stock, without the extremely low winter biomass which is found for species with an annual life cycle, would be antici pated for a species with a two-year life cycle such as c. glacialis. this is clearly demonstrated in the data from the central arctic ocean where the total biomass of c. glacialis from three different depth strata showed very low seasonal variation during an investigation from january t o decem ber (brodsky & nitikin 1955; grainger 1989). slagstad & tande (1990) presented model simu lations of c. glacialis based o n maximum popu lation abundances in arctic water of the barents sea which yielded biomass estimates of approxi mately 5 g c m-: for august (fig. 6). as compared to a maximum of 4 g c m-' for the total copepod community in balsfjorden. t h e simulated values should be considered as maximum values since conservative estimates of 3.2 and 2 . 9 g c-' are found for c. glacialis in arctic water east of svalbard at the end of july 1984 (see fig. 5 c ) . considerable regional variations in the popu lation density of c. glacialis are found. where notably lower biomasses (2.15, 1.35 and 0.29 g c m-' at stations 1. 2. and 3. respectively) are calanus glacialis i i j i i ~ 1 1 1 1 may ' jun ' jul ' aug ' sept time fig. 6. simulated standing stock of two year groups of calanus glucialk (adult females/civ/cv and ci-civ. respectively) from may to september in the barcnts sea. the population dynamics in the model are based on a two year life cycle. see slagstad & tandc ( 1 9 y o ) for further details. recorded in the polar front in july 1987 (fig. sb). an even lower biomass (0.14g c m-') was obtained in april 1986 in the same region (fig. 5a). compared t o atlantic water in the barents sea, there is a tendency in t h e arctic domain for a reduction in the quantitative importance of smaller copepods such as pseudocalanics s p , and oithona similis (hassel 1986), which normally reach maximum biomass during late summer and autumn in atlantic water. these species appear to have been replaced in trophodynamic terms by the youngest year-group (ci-chi) of c . glacialis which prevails during the oligotrophic arctic sum mer and autumn. potential production estimates of calanus glacialis production have been conducted in a dynamic model by combining data from population a n d bioenergetic studies during the productive period in the arctic (slag stad & tande 1990). based o n an estimate in primary production of 6 5 g c m ? , the model indicates a calanus production of 8.5 g c m-' during a simulation period of 150 days at 78"n east of svalbard. t h e physical-environmental data from the region of 78"n in 1984, where the ice started to disappear in may that year, was used in the standard run. d u e t o a two-year generation cycle, there is a bimodal seasonal pro duction with a maximum during august when the cohort produced during the spring has developed to ci-civ (fig. 7). a tendency for a high degree of mismatch between the spring bloom and the subsequent buildup of copepod biomass in calanus in north norwegian fiords and in the barents sea 399 14 12 h c'! 1 0 e 0 z 3 a 3 n b a phytoplankton 1 6 4 z + 0 calanus glacialis 0 3 d 0.12 n 2 0.06 0.00 time fig. 7. timing between copepod production in calanusglacialis civ-cv and ci-ciii during the productive period in the arctic. balsfjorden is inherent in the data presented above. in the arctic environment a two-year life cycle of c . glacialis should enhance an improved ability to exploit the spring bloom and reduce the general tendency for mismatch and the inter specific competition during the short productive season. if the rate of energy accumulation of calanus glacialis in the arctic food web is considered in terms of lipid classes, well-defined patterns emerge. the proportion of wax esters increases from ci to cv of c . glacialis, and the highest proportions are apparent in civ and cv (hen derson & tande 1988). when this is considered in relation to the primary production in the arctic, a substantial part of the wax ester deposition at the second trophic level tends to co-occur during the spring bloom (fig. 7). in the atlantic part of the barents sea and coastal waters of northern norway c. finmarchicus (the spring and early summer form) and pseudocalanus sp. (the late summer form) are the two quantitatively impor tant copepods which rely on wax esters as their depot lipid. (hopkins et al. 1984; henderson & tande unpubl. data; norrbin et al. 1990). a two year life cycle of c. glacialis gives rise to an analogous seasonal bimodal pattern of wax ester deposition in the arctic as found in the boreal copepod community. for herbivorous copepods, the extreme con ditions in the arctic should be viewed in relation to the large variability in the timing and duration of the periods in which food is available. this could be related directly to the interannual vari ation in the extension and retreat of ice during the productive season. climatic changes with possible consequence for the production of c. glacialis can therefore be demonstrated by simulating different durations of the primary production period (fig. 8). based on the standard model simulation, five different situations were defined by changing the ice conditions. this was done by letting the ice cover disappear during one weak starting in the middle of each month from april t o august, and simulate to the end of september. the potential production decreased from a maximum of 12.5 to 3 g c m-* when the onset of primary production changed from the middle of april to the middle of august. the ice conditions which could change the productive period from 5.5 to 1 . 5 months thus have the potential to reduce the production of c . glacialis by a factor of 4. although estimated production is higher than given in the standard 2t calanus glacialis apr may jun jul aug time fig. 8. effect of timing of ice melt. controlling onset of algal bloom in water column on production of calanus glacialis. 400 k . s. tande run for the model simulation in slagstad & tande (1990). the proportionate reduction in production should be considered relevant for this region. this means that during cold years, the climate would reduce the energy input to the lower trophic levels in the arctic. this is not a consequence of low temperature by itself. but rather a result of the extent of the southern distribution of the ice dur ing the productive season in the barents sea. calanus finmarchicus in neritic waters from the north sea. and in coastal waters o f norway t o the lofoten area. culanus ,finniurchiciis is considered t o produce two generations per year (samme 1934: 0 s t v e d t 1955: wiborg 1955: marshall & orr 1972: mat thews et al. 1978). an annual life cycle is found in oceanic waters in the north atlantic current from owsi (59"n; 19'w). northwards to the coastal waters of northern norway and t o the polar front in the barents sea (parsons & lalli 1988; tande 1982: tande e t al. 1985). t h e spawn ing behaviour of c'. ,finmarchicus has recently been described in detail in fjord areas of northern norway by die1 & tande (1991). they have sug gested that the onset of the phytoplankton spring bloom in the first days of april enhances the final maturation of ovaries and triggers the onset of the main spawning period. t h e overlap of the estimated minimum +week spawning period of the individuals leads t o a main reproductive phase of the population of approximately 3 weeks dur ation. during this period mean clutch size and spawning frequency are maximal. conclusive patterns of regional and seasonal variations in abundance and biomass are ham pered because of the relatively restricted numbers of appropriate time series of field data from the barents sea. maximum abundances of c. fin murchicus are found during the annual recruit ment period from mid-may to the end of june (tande & slagstad 1991). t h e peak in the biomass 5hiftr slightly. occurring two or three weeks later in the barents sea compared to balsfjorden. when the population has moulted to civ and cv (tande 19x1: tande & slagstad 1991). a n abun dance o f cill and civ. when they appeared as the highest proportions of the population. varied from 2-130 x 10'individuals m-: along a transect from 73 to 76"n in central parts of the barents sea at the end of june 1981 (hassel 1986). t h e abundance of ci t o civ c. jinmurchiclls moni tored from the e n d of may to mid-june 1987 from 73 t o 75"n to the east of bjarnoya, at an earlier stage in the annual recruitment period than above, varied by a factor of 10 (from 3-30 x 10') within the various developmental stages (unstad & tande 1991 this volume). population studies of calanus finmarchicus in march, april. and may 1989 from the atlantic current in the western part of the barents sea (fig. 9) show that males outnumbered females in march, i.e. the period of insemination occurs later than in balsfjorden (tande & hopkins 1981; tande 1982). t h e temperature was increased from 4 to 6°c at station 6, and from 3.5 to 5.5"c at station 12 from march t o may. regional vari ations in the sex ratio a t the different stations within the study region appear t o be consistent, and there is a less skewed sex ratio in favour of males at stations 6, 7 , 11, and 13 in march and april. o n 10 may the recruitment generation of c. finmarchicus was found as ci a n d cii at three of these four stations. this indicates that t h e onset of spawning and the subsequent build-up of the 10" 20" 30" 40" 50' 60" 70" 80" 10" 20" 30" 40" 50' 60" 70" / \ i / i / i \ \i '\ \ 40-80" mar i 70" 200 30' 40" f i g . y. rcgional variation in the abundanzc ( r n ' ) of c'cdnnus /inrnurchicu.\ m a l e s and females during march a n d april. and the s u h w q u e n t build-up of ci and cii in may l y 8 y in oceanic \ \ a t e n of thc barents s e a calanus in nc recruitment generation could differ by two weeks in open oceanic waters in the barents sea. this emphasises the importance of monitoring the bio logical system in relation to the hydrographic conditions in order to obtain a more precise dif ferentiation of the productive regime in the atlan tic part of the barents sea. a method of estimating the production of cal anus finmarchicus in boreal waters has been described by tande & slagstad (1991). model simulations estimate the annual primary pro duction to 70 g c m-z for open oceanic waters in the atlantic region of the sea; this is in general agreement with figures provided by rey et al. (1987). the estimation of calanus production is based on physical data from 1983 (fig. lo), start ing with a spawning stock of 2000 adult females m-2. population parameters scale the abundance of ci-cv according t o the maximum recorded in the atlantic region of the sea in 1983 (skjoldal et al. 1987) and give a potential production of 8.5 g c m-* (tande & slagstad 1991). copepodite stages iv and v are responsible for the largest proportion of this production and occur during the culmination period from mid-june to mid-july in the standard run. in terms of lipid deposition in c. finmarchicus, wax esters are laid down in increasing proportions during the copepodite phytoplankton i " m o'ot apr ' may ' jun ' jul i v 0 , calanus finmarchicus l i, 2 0.2 n 0.1 0.0 time fig. 10. timing bctwccn thc copcpod production in colanus finmarchicus (ci-cv and civ-cv, rcspcctivcly) and thc cul mination of the spring bloom in atlantic waters. 7rth norwegian fjords and in the barents sea 401 growth period (henderson & tande, unpubl. results). this is analogous to the situation described for the arctic domain, in which the time period of wax ester accumulation takes place fairly early in the productive period and is coupled to the intensive growth and production period in c. finmarchicus. regional variations in estimates of c. fin marchicus production in temperate and boreal waters have been reviewed in tande & slagstad (1991). recently, it has been suggested that cli matic events play a major role in the interannual variability of copepod populations in the bering sea (vidal & smith 1986). a higher biomass of smaller copepod forms (pseudocalanus spp. and oithona similis) was observed in warm years than in cold years on the middle shelf in the south eastern bering sea (vidal & smith 1986). this variation is related to size-dependent differences in metabolic rates, and copepods with small body sizes are proportionally more affected by tem perature than by food supply (vidal 1980a. b). this is exemplified for c. finmarchicus i n the barents sea, where the standard model predicts a production of 12, 8, and 4 g c m-z at tem peratures of 7 , 5, and 3°c. respectively (fig. 11). mortality according to the model is 0.11% d-i for the period from ni to ci. for cii-ciii, civ, and cv, the mortality is set at 0.077, 0.055, and 0.004, respectively (tande & slagstad 1991). this means that lower temperature would increase the stage durations and thus the total mortality of the recruiting generation. support for the increase in production at high environmental temperatures is not found as an increase in biomass of c. finmarchicus during the summer in warm years in the barents sea. calanus finmarchicus 1 time fig. 11. sensitivity analysis of the cffcct of temperature on thc potential productivity in calanus finmarchicus. 402 k . s. tande abundances at 74, 75, and 76"n along a transect in the polar front region in the beginning of june 1982 and 1983 differed in favour of the former year by a factor of 100 (skjoldal et al. 1987). although 1983 was generally a warmer year than 1982, there were temperatures of about 3.5 and 2.5"c, respectively, in the beginning of june in the uppermost 100 m at 75"n. these interannual differences should be interpreted with caution since the area of sampling is located in the polar front region where the biomass consisted both of c. glacialis and c. finmarchicus (skjoldal et al. 1987). for copepods with one generation per year, the overwintering stock of mature females is considered important for the subsequent pro duction period (tande & slagstad 1991), which also links predation to the copepod production the following year. although the differences in biomass found in the summer period from 1979 to 1984 could be explained by various factors. large interannual variations in copepod pro duction are highly probably in the barents sea. recently, the mortality and developmental rates of nauplii and copepodite stages of c. fin marchicus from neritic waters in northern norway have been obtained both at constant and con tinuously changing temperatures (pedersen & tande 1991). the temperature regimes in the experiments simulated three different rates of increase from 2°c: 0.2, 0.1, and 0°c d-i, which are within the range of variations in high latitude environments. the resulting mortality rates showed that increases in temperature yielded low mortalities for transition from nauplii and to cope podite stage i . thus an increase in temperature would reduce natural mortality in c. finmarchicus during the recruitment period. populations which experienced 2°c continuously showed in general higher mortality rates in addition to arrested dev elopment and mass mortality after 20 days of incubation. the temperature-dependent mor tality rate is. at the moment, difficult to quantify in ecological terms. the situation is complicated by a possible acclimation effect of the over wintering temperature experienced by the adult females (pedersen & tande 1991). the tem peratures experienced by overwintering females appear t o modify the relationship between tem perature and developmental rates of the offspring. this means that there is a certain degree of physiological plasticity to temperature in c. finmarchicus which could be of ecological rel evance to the species in the barents sea. vertical organisation and temporal shifts in the lower food chain. the temporal succession and match-mismatch between primary production and the growth cycles of calanus glacialis and c. finmarchicus, described above reinforce the question of food limitation of these copepods during the pro ductive period in the barents sea. the highly layered structure of the pelagic eco system has been suggested as the primary spatial variance in the ocean (longhurst 1981). in coastal waters of northern norway and in the barents sea the seasonal (ontogenetic) vertical migration patterns in c. finmarchicus tend to coincide with the annual generation cycle (unstad & tande 1991). in these areas ci-ciii tended t o aggregate in the uppermost waters in may and june (tande 1988b; unstad & tande 1991). ontogenetic ver tical migrations were apparent in almost all locations studied, and the maximum abundance was, to a variable degree, associated with the maximum of algal biomass. the magnitude of diurnal vertical migration varied, and consider able differences in vertical translocations in the abundance were found in malangen as compared to grotsund and balsfjorden (tande 1988b). in the barents sea, the vertical separation of cope podite stages tended to increase at locations with the absence of a well-defined phytoplankton maximum, both at high and low phytoplankton standing crops. in waters where c . finmarchicus and c. glacialis coexisted at high population den sities, a tendency toward a clear bimodal dis tribution pattern was found which could facilitate a decrease in competition for similar food resources. the phytoplankton biomass is often both ver tically and regionally dominated by the prym nesiophyte phaeocystis pouchetii during the most intensive growth and production period of c. finmarchicus. given a suitable prey size c. fin marchicus grazed on both diatoms and colonies of the gelatinous algae at equal rates in laboratory studies (hansen et al. 1991). a linear relationship between gut content and food concentrations below 10 pg plant pigment i ' was found. these data emphasise that ingestion in c. finmarchicus might be linearly proportional to ambient food concentration in may and june (cf. fig. 10). although p. pouchetii is likely to sustain growth in all life stages of c. finmarchicus during the culmination period and the early part of the oli calanus in north norwegian fjords and in the barents sea 403 gotrophic summer period, substantial regional variations in algal biomass and c. finmarchicus abundance was found both in the fjords in north ern norway during 1986 (tande 1988b) and in the barents sea in 1987 (unstad & tande 1991). longterm interannual variations in abundance and biomass of calanus spp. are found during the summer periods from 1959 to 1977 (degtereva 1979) and from 1979 t o 1984 (skjoldal & rey 1989) in the southwestern and central parts of the barents sea, respectively. the annual production of calanus has been found t o be positively cor related t o the size of the overwintering stock of adult females both in model analysis (tande & slagstad 1991) and also in field studies from the north sea (colebrook 1979). thus food-limited growth and production by c. finmarchicus in atlantic water of the barents sea is more likely to take place in regions with high copepod abun dances than through mismatch in the cycles between the diatoms, p . pouchetii, and the cope pod. the feeding conditions of the different life stages of c. glacialis during the oligotrophic period in the arctic are defined to a large extent by the algal species sedimenting from the euphotic layer (c.f. eilertsen et al. 1989). colonial forms such as p. pouchetii and the mixotroph dinobryon sp. are common in the layer, although low num bers of diatoms could generally be indicative of selective grazing. in situ feediqg rates above those expected from ambient diatom concentrations are found at locations where colonial forms prevail, increasing the trophodynamic importance of the colonial forms (hansen et al. 1990). alternative food organisms have not been considered in these studies, but diatoms, flagellates, and ciliates were found in the diets of calanus spp. in polynyas, at the ice edge and in open waters in june and july in the fram strait (barthel 1988). recent data show that protistan plankton consume a greater fraction of plant production than metazoa, and protista would alter the overall quantity and ver tical pattern of carbon flow between plant pro ducers and calanus spp. in the arctic. a deep-water chlorophyll maximum layer (scm) is usually formed around the nutricline during the arctic summer period by a gradual descent of the spring surface blooms (tande & bimstedt 1985; eilertsen et al. 1989; longhurst & harrison 1989). the scm is a temporal phenomenon which tracks the deepening mixed layer, lasts during the oligotrophic period, and is eroded at the end of the productive period in autumn. the situation has been clearly demon strated in arctic waters east of svalbard at the end of july (eilertsen et al. 1989). here the vertical profiles in algal biomass (in terms of carbon) tracks the phytoplankton carbon assimi lation, although the data do not facilitate a sep aration of the production maximum from the algal biomass maximum. however, the biomass of the principal herbivores (i.e. calanus spp.) are found within the algal production layer, although they are shifted slightly towards deeper waters. onto genetic differences in vertical distributions within both c . glacialis and c. hyperboreus offset the vertical profiles of grazing and algal production to an even larger extent. vertical profiles of algal production and grazing vary extensively in the region of the polar front during the post-bloom period (hansen et al. 1990). this emphasises the anticipated spatial heterogeneity which is often found in the vertical coupling of algal production and zooplankton grazing in frontal systems due to variability in the physical environment. on the other hand, the striking offset of the vertical distribution of the primary producers relative to macrozooplankton during the oligotrophic arctic summer period favours the existence of the scm. therefore, the question of food limitation in c . glacialis in the arctic environment should be viewed in an evolutionary context where the feed ing behaviour. vertical behavior and life cycle strategy are adjusted to facilitate an optimal har vesting strategy of the arctic phytoplankton com munity both on a temporal and a regional scale. calanus productivity: an interplay between endemic and advective processes the large-scale periodic changes in temperature are shown by temperature anomalies (fig. 12) during a 25 years period in the kola section 33"30'e) in the barents sea (midttun & loeng 1987). warm and cold periods alternate in periods of 3-5 years and are closely related to the ice conditions (blindheim & loeng 1981). midttun & loeng (1987) have suggested that these variations are related to variations in the inflowing atlantic water. thus, temperature changes in the eastern part of the barents sea usually occur one year later than in the western part (loeng et al. 1983). 404 k . s. tande l) 0.5 0.5 -4 " 0 0 -0.5 -0 5 -1.0 .l .o 1 5 -1.5 fig i 2 sca temperature anomalie, durlng the period from 1960 to 1985 along the kold bectlon in the bdrcnts sea redrawn from midttun & loeng (1087) to what extent the temperature changes shown in fig. 12 reflect variations in inflowing activity or properties of the atlantic water is debatable. however, it is obvious that the atlantic water is modified by local processes in the barents sea, where cooling and ice formation result in water of higher density. cooling and ice formation change inflowing atlantic water into dense bottom water, which promotes outflow through the chan nels (particularly through bjarnoyrenna) leading out from the barents sea. a large inflow would then be followed by a period of cooling and modi fication of the atlantic water. this could be one reason for the apparently cyclic variation in the ocean climate particularly i n the atlantic region of the barents sea. the functioning of calanus glacialis and c. jinniarchicus within these physical conditions could be described in different scenarios. ex tremely cold years are associated with a southern distribution of the ice during the spring. this situation would tend to decrease the potential secondary production i n arctic and atlantic waters. but through different mechanisms. the arctic domain should be considered as an unpre dictive environment for c. glacialis since the northward-flowing water currents in the eastern area would counteract the anticipated increase i n production following the ice withdrawal. this would tend to delay the onset of the spring bloom with a consequently negative effect on the poten tial production of the proportion of the population present i n these regions. the opposite situation could be found for c. glacialis in the western region where the arctic water flows in the oppo site direction. cold periods would not tend to alter the overall pattern of primary production in the atlantic water, but would tend to lower the potential productivity in "@marchicus" water more directly through temperature. the cooling would enhance the negative effect on dev elopment and mortality rates because the antici pated temperature increase during the spring and early summer would be low or absent i n certain regions. advection would increase the transport of biomass to the barents sea. increase the extent of the productive "finmarchicus" area, and pro mote the endemic productivity in both the atlan tic and the arctic region of the barents sea. the food chain from calanus to planktivorous fish and gelatinous zooplankters is therefore dependent upon productivity changes endemic to the sea and upon advection of biomass from polar water, the norwegian sea, and the norwegian coastal current. the barents sea is considered as a nursery area for the young year classes of atlanto-scandian herring (dragesund et al. 1980). capelin (mallofus uillosus) and polar cod (boreogadus saida) are endemic planktivorous fishes inhabiting both atlantic and arctic waters (hamre 1985; monstad & gjosaether 1987). although large fluctuations in the stocks have been detected during the 1970 and 1980s. skjoldal & rey (1989) believe that these two species act as competitors on the zooplankton biomass and production. the interannual variability in plank ton biomass found in the different regions of the sea (i.e. degtereva 1979; skjoldal & rey 1989) is probably related to large scale processes. the way in which these trophodynamic couplings are expressed in quantitative dynamic terms is at present largely unknown. in order to substantiate these important links, future research in the bar ents sea should be designed to cover three topics: firstly, a description of the dynamics in the large scale advective processes, especially from the north atlantic and the norwegian coastal cur rents with monitoring of the biomass involved and the biological consequences for the different regions in the barents sea; secondly, a more elaborate understanding of the harvesting strat egy of fish on the principal planktivores on cope pods and krill in the different regions of the barents sea proper; and thirdly, experimental studies in conjunction with field investigations in order to further substantiate the effect of climate on the biological rate processes among key species in the atlantic region of the barents sea. acknowledgemeno. this work i s part of the pro mare pro grammc and was financially supported in part by the nonvcgian fisheries research council (nffr). the author wishcs to thank two anonymous reviewers for valuable comments on the manu calanus in north norwegian fiords and in the barents sea 405 script and d. slagstad for performing thc simulation test and for the stimulating discussions. references adlandsvik. v. 1989: wind-driven variations in the atlantic inflow t o the barents sea. coun. meet. int. coun. expor. sea (c:18). 1-12. barthel, k.-g. 1988: feeding of three calanw species on dif ferent phytoplankton assemblages in the greenland sea. meeresforsch. 32, 92-106. berggreen. u.. hansen. b. & kierboe. t. 1988: food size spectra. ingestion and growth of the copepod acartia tonsa during development: implications for determination of cope pod production. mar. biol. 99. 341-352. blindhcim. j . & loeng. h. 1981: on the variability of atlantic influence in the norwegian and barcnts sea. fisk.dir. skr. ser. hauunders. 17. 161-189. brodsky, k. a. & nitikin. m. m. 1955: hydrobiological work. pp. 401465 in somov, m. m. (ed.): materialy nabliudenii nauchno-issledouatel skoi dreifuiushchel stantsii 1950151 goda. izd. “morskoi transport” 1954-1955, 1 (transl. am. meteorol. soc.). colebrook. j. m. 1979: continuous plankton records: seasonal cycles of phytoplankton and copepods in the north atlantic ocean and the north sea. mar. biol. 51, 23-32. conover, r. j . 1988: comparative life histories in the genera calanus and neocalanus in high latitudes of the northern hemisphere. hydrobiologia 1671168. 127-142. corkett, c. j.. mclaren, i. a. & sevigny, j.-m. 1986: the rearing of the marine calanoid copepods calanusfinmarchicus (gunnerus), c . glacialis jaschnov and c . hyperboreus kreyer with comment on the equiproportional rule. pp. 539-546 in schriver. g . . schminke & shih, h. k. (eds.): proceedings of the second international conference on copepoda, ottawa. cushing, d. h. & dixon. r. r. 1976: the biological response in the sea to climatic changes. adu: mar. biol. 14. 1-122. davis. c. s. 1984: predatory control of copepod seasonal cycles on georges bank. mar. biol. 82. 31-40. degtereva. a. a . 1979: regularities of quantitative dev elopment of zooplankton in the barents sea. trudy pinro. murmansk 43. 22-53 (in russian). dickson, r. r.. midttun. l. & mukhin, a . 1. 1970: the hydrographic conditions in the barents sea in august-sep tember 1965-1968. pp. 3-24 in dragesund. 0. (ed.): inter national 0-group fish surveys in the barents sea 1965-1968. i n t . coun. explor. sea. cooperative res. rep. ser a , no. 18. diel. s. 1989: zur lebensgeschichte dominanter cope podearten (calanus finmarchicus, c . glacialis. c . hyper boreus. metridia longa) in framstrasse. ph.d. thesis. christian albrechts university, kiel. 140 pp. diel. s. & tande. k. s. 1991: does the spawning of calanus finmarchicus in high latitude follow a predictable pattern? a case study. mar. biol. in press. dragesund. 0.. hamre, 1.. & ultang. 0. 1980: biology and population dynamics of the norwegian spring spawning herring. rapp. p.-u. rkun. cons. int. explor. mer 177. 43 71. eilertsen, h. s . 1983: planteplankton f0r og etrer uassdrags reguleringen i skjomen 197k1972. ridgivende utvalg for fjordundersekelser, skjomenprosjektet. oslo. 60 pp. (in norwegian) eilertsen, h . c. & tassen, j. p. 1984: investigations on the plankton community of balsfjorden, northern norway. the phytoplankton 19761978. environmental factors, dynamics of growth, and primary production. sarsia 6 9 . 1-15. eilcrtsen. h . c..tande. k . s . & hegscth, e. n . 1989: potential of herbivorous copepods for regulating the spring phy toplankton bloom in the barcnts sea. rupp. p . ~ j . reun. cons. lnt. explor. mer 188. 154-163. eilertsen. h . c.. schei. b. & taasen. j. p. 1981: investigations on the plankton community of balsfjorden, northern norway. the phytoplankton 1976-1978. abundance, species com position. and succession. sarsia 6 6 , 12y-141. eilertsen. h. c.. tande. k. s. & taasen. j. p. 1989: vcrtical distribution of primary production and grazing by calanus glacialis jaschnov and c. hyperboreus kreyer in arctic waters (barents sea). polar biol. 9 , 253-260. eilertsen. h. c.. taasen. j. p. & weslawski. j . m. 1989: phytoplankton studies in the fjords of west spitsbergen: physical environment and production in spring and summer. j. plank. res. 1 1 . 1245-1260. eilertsen. h . c.. hopkins. c. c. e.. falk-pctersen, s . & tande. k . s . 1981: ecological investigations on the plankton community of balsfjorden. northern norway. program for the project, study area, topography, and physical environ ment. sarsia 6 6 . 25-34. evans, f. 1977: seasonal density and production estimates of the commoner planktonic copepods of northumberland coastal waters. esruar. coastal mar. sci. 5 , 223-241. gaarder, k. r. 1938: phytoplankton studies from the tromse district 1930-31. trom.50 mus. arsh. 55(i). 1-159. grainger. e. h. 1961: the copepods calanus glacialis (jaschnov) and calanus finmarchicus (gunnerus) in canadian subarctic waters. j . fish. res. bd. can. 18. 66% 678. grainger, e. h. 1989: vertical distribution of zooplankton in the central arctic ocean. pp. 4 m in rey, l., alexander. v. (eds.): proc. 6th conf. com. arctique internat.. is15 may 1985. e. j . bill, leiden. grenvik. s . & hopkins. c. c. e . 1984: ecological investigations of the zooplankton community of balsfjorden, northern nor way: generation cycle. seasonal vertical distribution, and seasonal variations in body weight and carbon and nitrogen content of the copepod metridia longa (lubbock). j . exp. mar. biol. ecol. 80. 93-107. hamre. j. 1985: assessment and management of barents sea capelin. pp. 5-24 in h. g j ~ s z t e r (ed.): proc. soviet-norweg ian symp. barents sea capelin. institute of marine research, bergen. norway 1989. hansen, b.. tande. k. s . & berggreen. u . c . 1991: on the trophic fate of phaeocysris pouchetii (hariot) 111. functional responses in grazing demonstrated on juvenile stages of cal anus finmarchicus (copepoda) fed diatoms and phaeocystis. j. plankton res. 12. 1177-1187. hansen, b . , berggreen. u . . tande, k. s. & eilertsen, h . c. 1990: post-bloom grazing by calanus glaciulis. c . fin marchichus and c. hyperboreus in the region of the polar front. barents sea. mar. biol. 104, 5-14. hassel, a . 1986: seasonal changes in zooplankton composition in the barents sea, with special attention to calanus spp. (copepoda). j . plankton res. 8 . 329-339. henderson. r. j . & tande. k. s. 1988: lipid composition of copepodite stages and adult females of calanus glaciulis in arctic waters of the barents sea. polar biol. 8 . 333-339. heimdal. b. r. 1974: composition and abundance of phy 406 k . s . tande toplankton in the ullsfjord area. north norway. astarre 7. helland-hansen. b. & nanscn. f. lw: the norwegian sea. fisk.dir. s k r . ser. haouriders. 2(2). 1-360. hirchc. h.-j 1989: egg production of the arctic copepod calanus glacialis: laboratory experiments. mar. biol. 10-7. 31 1-318. hirche. h.-j. & bohrer. r . n. 1987: reproduction of the arctic copepod colonusglacialis in fram strait. mar. biol. 94. 11 17. hopkins. c. c e.. tande. k . s . . grenvik. s . & sargent. j . r . 1984: ecological investigations of the zooplankton com munity of balsfjorden. northern norway: an analysis of growth and overwintering tactics in relation to niche and environment in merridia longa (lubbock). calanus f i n marchicus (gunncrus) thysanoessa inermis ( k r ~ y e r ) and t raschii (m. sars). j . exp. mar. biol. ecol. 82. 77-99. hopkins. c c. e.. tande. k . s . . sargent. j . r. & schweder, t . 1985: ecological investigations of the zooplankton com munity of balsfjorden. northern norway: growth. and quanti fication of condition. in relation to overwintering and food supply in merridia longa. calanusfinmarchicus. thysanoessa inermis and 71 raschii. pp. 83-101 in gray. j . s . and chri stianscn. m. (eds.): marine biology of polar regions and effeco of stress on marine organirms. j . wiley and sons. huntley. m . strong. k . w. & dengler. a. t. 1983: dynamic and community structure of zooplankton i n the davis strait and northern laborador sea. arcric 3 6 . 14%161. jaschnov. w. a. 1967: water masses and plankton. i . species of calanus finmarchicus 5.1. as indicators of definite water masses. zool. zh. 40. 1314-1334 (in russian). jaschnov. w a . 1970: distribution of calanus species in the seas of the northern hemisphere. fnr. reu. ges. hvdrobiol. hydrogr. 5 5 . 197-212. jaschnov. w. a 1972: on the systematic status of calanus glacialis. calanus finmarchicits. and calanus helgolandicus. critsraceana 22. 27%284 lilein breteler. w . c. m . franz. h. g . . & gonzalcz. s. r . 1y82: growth and development of four calanoid species under experimental and natural conditions. nerh. 1. sea res. 16. 195-207. lindley. j . a iyyo. distnbution of overwintering calanoid copepod eggs in sea-bed aedimcnts around southern britain. mar. biol. 104. 209-217. loeng. h . 1991. features of the physical oceanographic con ditions of the barents sea. polar res. pp. $18 in sakshaug. e . . hopkins. c. c. e . & britsland. n. a . (eds.): proccedings of the pro mare symposium on polar marine ecology. trondhcim. 12-16 may i y y o . polar research l o ( ] ) . loeng. h. 8: midrtun. l . lyx4: climatic variation, in the barents sca during thc i y ~ o ' s , coun. m e e t . lnr. coun. explor mer lg:15). 1-10 (mimeographed). locng. h. d l'inje. t . e . 1979: on thc sca icc conditions i n the greenland and the barcnts seas. pp. 163-176 in proc. 5rh inreniur c o n f . port ocean engineering and arcric con dirioric the norwegian institute of technology. university of trondhcim l o e n g . h . . nakl.cn. 0 . b: rakncs. a . 1983: variation, i n thc gcographical distribution of cod in thc barcnt, sea in thc period i y 7 i i y r i . fisken og hawrr. 19x1 (4). 1-16 ( i n noruegian. english abstract) longhurst. a r . 1981: biostat. an cxpcrimcnt in ocean plankton ecology. bedford insrirure of oceanography. reporr series bi-r-81-13, 1-105 17-42. longhurst. a . r . & harrison, w . g . 1989: the biological pump: profiles of plankton production and consumption in the upper ocean. progr. oceanog. 22. 47-13, mclarcn. i . a . . tremblay, m. j . . corkett. c. j. & roff. j . c. 1989: copepod production on the scotian shelf based on life history analysis and laboratory rearings. can. 1. fish. aquat. sci. 46. 564l582. maclcllan. d. c. 1967: the annual cycle of certain calanoid species in west greenland. can. 1. zool. 45. 101-115. marshall, s . m. & o r r , a. p. 1972: the biology of a marine copepod calanus finmarchicus (gunncrus). oliver & boyd, edinburgh. 195 pp. matthews. j . b. l. 1967: continuous plankton records: the geographical and seasonal distribution of calanus f i n marchicus s.1. in the north atlantic. bull. mar. ecol. 6.252 2 7 3 . matthews. j . 8. l., hestad, l. & bakke. j. l. w. 1978: ecological studies in korsfjorden, western norway. the gen erations and stocks of calanus hyperboreus and c. j i n marchicus in 1971-1974. oceanologica acta i . 277-284. midttun. l. & loeng. h . 1987: climatic variations in the barents sea. pp. 113-27 in loeng. h. (ed.): the efferr of oceanographic condirions on distribution and population dynamics of commercialfish stocks in the barenrs sea. proc. 3rd soviet-norwegian symp., murmansk 2 6 2 8 may 1986. inst. mar. res.. bergen. monstad. t. & gjasaeter. h . 1987. observations on polar cod (boreogadus soida) in the barents sea 1973 to 1986. 1ces c . m . 1987/g:13. neumenko. e. a . 1979: life cycles of some copcpods from the southeastern bering sea. hydrobiol. j . 15, 2 s 2 7 . norrbin. m. f. 1987: overwintering strategies of pseudocalanus elongatus boeck and acarria longiremis lilljcb. in balsfjor den. northern norway. seasonal abundance. size variation, sex ratios. and gonad maturation. fil. lic. thesis, university of gothenburg. norrbin. m. f.. olsen. r . e . & tandc. k . s . 1990: seasonal variation i n lipid class and fatty acid compositions of t w o small copepods in balsfjorden. northern norway. mar. b i d . 105. 205-211. 0stvedt. 0. j . 1955: zooplankton investigations from weather ship m in thc norwegian sea. 1948-49. hualr. skrifter 40, 1 93. parsons. t. r. & lalli. c. m. 1988: comparative oceanic ecology of the plankton communities of the subarctic atlantic and pacific oceans. oceanogr. mar. biol. ann. reo. 26.317 359. pcdersen. g . & tande. k . s . 1991: physiological plasticity to temperature in calanus finmarchirw. reality or artefact'? j . e x p mar. r i d ecol. i n presq. pertzova. n. m. 1974: life cycle and ecology of a thermophilous copepod cenrrophages hamarus in the white sea. zool. zh. 53. 1013-1022. prygunkova. r . v . 1969: the development cycle of calanm glacialis i n the white sea. dokl. a k a d . nauk sssr 182. 14471450 rey. f . . skjoldal. h . r . & slagstad. d. 1987: primary pro duction i n relation to climatic changes in the barents sea. pp. 29-46 i n loeng, h . ( e d . ) : the effect of oceanographic conditions on disrriburrun and popularion dynamics of com rnerciul f i s h s m c k s in the barents sea. proc. 3rd sovict norwegian symp.. murmansk 2 6 2 8 may 1986. inst. mar. r e s . , bergen. runge. j . a . . mclarcn. i . a , . corkett, c. j.. bohrer. r. n. calanus in north norwegian fjords and in the barents sea 407 & kislow, j . a . 1986: moulting rates and cohort development of calanus finmarchicus and c. glacialis in the sea off southwest nova scotia. mar. biol. 86, 241-246. sakshaug, e. 1972: phytoplankton investigations in trondheimsfjord, 1963-1966. k . norske videns. selsk. skr. sambrotto. r. n., niebauer. h. j.. goering, j . j . & iverson, r. l. 1986: relationships among vertical mixing, nitrate uptake, and phytoplankton growth during the spring bloom in the southeast bering sea middle shelf. cont. shelf res. 5 , 161-198. schei, b. 1974: phytoplankton investigations in skjomen, a fjord in north norway, 1970-1971. asrarre 7 , 4 3 5 9 . skjoldal. h. r. & rey. f. 1989: pelagic production and varia bility of the barents sea ecosystem. pp. 241-286 in shcrman. k. & alexander. l. a. (eds.): biomass yieldr andgeography of large marine ecosysrems. aaas selected symposium 11 1. westview press. skjoldal, h. r.. hassel. a , , rey, f. & loeng, h. 1987: spring phytoplankton and zooplankton reproduction in the central barents sea in the period 1979-1984. pp. 59-89 in loeng. h. (ed.). the effect of oceanographic conditions on distribution and population dynamics of commercial fish stocks in the barenrs sea. proc. 3rd soviet-norwegian symp., murmansk 2 6 2 8 may 1986. inst. mar. res.. bergen. slagstad, d.. & tande. k. s. 1990: growth and production dynamics of calanus glacialis in an arctic food web. mar. ecol. prog. ser. 63, 189-199. smith, s . l. 1990: egg production and feeding by copepods prior to the spring. bloom of phytoplankton in fram strait, greenland sea. mar. biol. 106. 59-69. sqmme, j . d. 1934: animal plankton of the norwegian coast waters and the open sea: 1. production of calanus fin marchicus (ounnerus) and calanus hyperboreus ( k r ~ y e r ) in the lofoten area. rep. norw. fish. inuesr. 4(9), 1-163. sverdrup, h . u. 1953: on conditions for the vernal blooming of phytoplankton. j. cons. perm. int. explor. mer 18.287 295. tande, k. s. 1982. ecological investigations on the zooplankton community in balsfjorden, northern norway: generation cycles, and variations in body weight and body content of carbon and nitrogen related to overwintering and repro duction in the copepod calanus finmarchicus (gunnerus). ./. exp. mar. biol. ecol. 62, 129-142. tande, k. s. 1988a: aspects of developmental and mortality rates in calanus finmarchicus related t o equiproportional development. mar. ecol. prog. ser. 44. 51-58. tande, k. s . 1988b: an evaluation of factors affecting vertical 1972(1). 1-56. distribution among recruits of calanus finmarchicus i n three adjacent high-latitude localities. hydrobiologia 167/168.115 126. tande, k. s. & bimstedt, u. 1985: grazing rates of the copc pods calanus glacialis and c. finmarchicus in arctic waters of the barents sea. mar. biol. 87. 251-258. tande, k. s. & gr~invik, s. 1983: ecological investigations on the zooplankton community of balsfjorden. northern norway: sex ratio and gonad maturation cycle in the copepod metridia longa (lubbock). 1. exp. mar. biol. ecol. 71. 43 54. tandc. k. s. & hopkins, c. c. e . 1981: ecological inves tigations on the zoo plankton community in balsfjordcn. northern norway: the genital system in calanusfinmarchicus and the role of gonad development in overwintering strategy. mar. biol. 63, 159-164. tande. k. s . & slagstad. d . 1991: rcgional and intcrannual variations in biomass and productivity of calanus fin marchicus in subarctic environments. oceanologica acra. in press. tande, k. s.. hassel. a . & slagstad, d . 1985: gonad matu ration and possible life cycle strategies in calanus f i t ? marchicus and c. glacialis in the northwestern part of the barents sea. pp. 141-157 in gray, j . s . and christianscn. m. (eds.): marine biology of polar regions and effecrs of stress on marine organisms. j . wiley and sons. unstad, k. & tande, k. s. 1991: depth distribution of calanus finmarchicus and c. glacialis in relation to environmental conditions in the barents sea. pp. 4 0 w 2 0 in sakshaug. e.. hopkins, c. c. e. & britsland. n. a . (eds.): proceedings of the pro mare symposium on polar marine ecology. trondheim. 12-16 may 1990. polar research lo(2). vidal. j . 1980a: physioecology of zooplankton. 1. effects of phytoplankton concentration. tcmperaturc, and body size on the growth rate of calanus pacificus and pseudocalanus sp. mar. biol. 56. 135146. vidal. j . 1980b: physioecology of zooplankton. 11. effects of phytoplankton concentration. tempcrature. and body size on the development and moulting rates of calanus pacificus and pseudocalanus sp. mar. b i d . 56. 135146. vidal. j . & smith. s. l. (1986). biomass. growth, and dev elopment of populations of herbivorous zooplankton in the southeastern bering sea during spring. deep-sea res. 33. 523-556. wiborg. k. f. 1955: investigations on zooplankton i n coastal and offshore waters of western and northwestern norway. with spccial rcfcrcnce to thc copcpods. fisk.dir. skr. ser. hauunders. i 1 ( i ) . 1-246. the late weichselian glacial maximum in western svalb ar d jan mangerud, magne bolstad, anne elgersma, d a g helliksen, jon y. landvik, anne katrine lycke, ida lbnne, om0 salvigsen, tom sandahl and hans petter sejrup mangerud, j . , bolstad, m., elgersma, a., helliksen, d., landvik, j. y., lycke, a. k., l ~ n n e , i.. salvigsen, o., sandahl, t . & sejrup, h . p. 1987: the late weichselian glacial maximum in western svalbard. polar research 5 n . s . , 275-278. jan mangerud, magne bolstad, anne elgersma, dog helliksen, jon y . landoik, anne katrine lycke, ida lpnne, tom sandahl and hans pener sejrup, department of geology, sect. b, uniuersiry of bergen, allkgaten 41, n-5007 bergen, norway; otto saluigsen, norsk polarimtitutt, p . o . box 158, n-1330 oslo lufthaun, norway. the glacial history of svalbard and the barents sea during the late weichselian has been much debated during the last few years; reviews are presented by andersen (1981), boulton et al. (1982), elverhbi & solheim (1983) and vorren & kristoffersen (1986). in our opinion (mangerud et al. 1984) it is now demon strated that a relatively large ice-sheet complex existed over most of svalbard and large parts (if not all) of the barents sea. one of the main arguments for a large ice sheet is the pattern of uplift, including the 9,800 b.p. date on the 100 m shoreline in kong karls land (salvigsen 1981). important unresolved problems include how large that ice sheet was, the location of the different ice domes and ice fronts, the age and duration of the glacial maximum, and the deglaciation history. we will here report on these problems bringing some results from the van mijenfjorden and isfjorden area (fig. 1); a more com prehensive paper is in preparation. evidence radiocarbon dates on shells, of which most were collected in stratigraphical positions that suggest they lived shortly after the deglaciation, are plotted on fig. 1. the pattern indicates that the ice front halted at aksel~iya at the mouth of van mijenfjor den forsomecenturiesaround 11,000yearsb.p. thisconclusion is substantiated by the sea level history, because the 11,000 year shore line which was mapped along the coast from bellsund t o isfjorden (landvik et al. 1987) does not continue into van mijenfjorden, where only lower and thus younger shorc lines occur. in a section in skilvika (fig. 1) the fabric in the only existing late weichselian till shows deposition from a glacier flowing nnw, out recherchefjorden. radiocarbon dates from a glacio marine clay just above the till gave 12,830 -t 210 (t-6ooo) and 1 2 , 5 7 0 t 160 (ua-280) years b.p. (fig. 1). below this till a horizon with frost-weathered stones indicates subaerial conditions. along the coast from bellsund to isfjorden we have mapped glacial striae, perched boulders, and other evidence for ice lobes flowing out of the valleys (fig. 1). between the valleys conclusive observations for or against glaciation are lacking (landvik et al. 1987). linnkdalen is the westernmost valley on the south shore of isfjorden (fig. 1). all mapped glacial striae and till fabrics indicate an ice movement towards the north, i.e. down valley. we assume that they exclude the possibility of an ice stream coming out of isfjorden at the time of their formation. strati graphic sequences along the river linntelva cover much of the weichselian; all pebble counts, till fabric analyses and sedimentary structures measured in these sediments record a transport from local sources. we conclude that the last ice advance out isfjorden (ohta 1982) probably predates this sequence, and that the early weichselian is a minimum age for such a glaciation. the deglaciation of linntdalen can be dated just prior t o 11,600 years b.p. based on accelerator radiocarbon dates on molluscs from the basal glaciomarine clay in cores raised from the lake linntvatnet (svendsen et al. this volume). the extent and configuration of the glaciers during the late weichselian ice maximum a complex calving bay in bellsund can be reconstructed (fig. 1). a fjord glacier in van mijenfjorden grounded on akselbya, while ice streams out van keulenfjorden and recherchefjorden calved along the southern border of bellsund. this scenario represents a definite minimum extension for the late weich selian ice and a possible, and indeed reasonable, model for the ice maximum. based on the deglaciation dates from skilvika, the reconstruction can be dated just prior to 12,700 years b.p. the van mijenfjord glacier remained at a k s e l ~ y a until after 11,ooo b.p. currently, we have no observations that suggest a substantially larger late weichselian glaciation around bellsund. the van mijenfjord glacier may have been an outlet glacicr from the barents sea ice sheet. however, the date from agardhbukta (fig. 1) suggests that the eastern coast of spits bergen was ice free before kjellstrbmdalen on the western side, so at least during the final stages of the deglaciation the valley glaciers t o the west originated from local ice domes on spitsbergen. during the glacial maximum, ice was no doubt contiguous from van mijenfjorden to the barents sea, even if the ice was dynamically separated into several domes. glaciers coming out of van keulenfjorden and weichselian glacial maximum in western sualbard 277 ing the location of an ice front. boulton (1979) postulated a young ice advance over the kapp ekholm site in billefjorden, based on a young radiocarbon date from a till. however, it was demonstrated (mangerud & salvigsen 1984) that shells in living position above that till yielded infinite ages. this had in fact been described before by troitsky et al. (1979) who assumed that late weichselian ice had not overrun the site because no till covers the sediments with the ‘old’ radiocarbon and tl dates. however, they generally reconstructed much smaller late weichselian glaciers on spitsbergen than we d o in this paper. our plan is to reinvestigate the site at kapp ekholm and the surrounding area before drawing any final conclusion. we propose a model of the late weichselian glacial maximum (fig. 1) with two styles of glaciation: local ice domes on western spitsbergen and a major barents sea ice sheet, and with van mijenfjorden glaciated whereas most of isfjorden was ice free (mangerud et al. 1984). age and duration of the late weichselian ice maximum the timing of the high-latitude glacial events in the svalbard barents sea. relative t o the mid-latitude glaciation of scan dinavia, or to antarctica. is crucial for understanding the dynamic response of the earth’s systems to the orbital forcing of climatic change (denton et al. 1986). two views are held for the age of the late weichselian ice maximum in svalbard: around 18.000 years b.p. (e.g. denton & hughes 1983) and around 11.ooo years b.p. (e.g. boulton et al. 1982). neither of the two assumed ages are contradicted by field observations, even though our observations rather point to there being an age between the two. as pointed out above, there were two glacial systems in this part of the arctic: a barents sea ice sheet complex that was mainly marine-based, and local, mainly land-based ice domes on spitsbergen. possibly the two systems were not in phase, neither during their growth and maximum nor during their decay. the relative timing will be important to understand how the two systems responded to sea level and climatic changes. we assume that the late glacial uplift of western spitsbergen mainly was a glacio-isostatic response to decay of the barents sea ice sheet. the deglaciation of the local ice domes on spits bergen occurred during that period of emergence, 12.000 to 9.000 years b.p., and was thus roughly in phase with the deglaciation of the barents sea ice sheet. with the accuracy of available data. we cannot resolve whether there in detail were leads or lags between the two glacial systems during the deglaciation. from svalbard many finite radiocarbon dates in the interval 15.000 to 40,000 years b.p. are reported, most, if not all, from samples consisting of several mollusc individuals or fragments. thus. the ages might in many cases represent means of mixed age populations. we obtained a date of 16,760 2 180 (t-6617) for shell fragments from a terrace 65 m a.s.1. in linntdalen. well inside the late weichselian boundary. subsequently obtained amino acid d/l ratios from 0.017 to 0.028 on different fragments suggest that it was a mixed age population, an assumption confirmed by an accelerator date of 11,000 f 190 (ua-279) on the fragment with the lowest d/l ratio. the youngest radiocarbon ages we have obtained for molluscs in lioing position inside the late weichselian ice limit are 36,100 2 830 (t-5211) and 35,900 2 500 (t-6618). as with all old shells, they might be contaminated, so the age is a minimum age. however, a ‘low age’ is supported by low d/l values, described below. the shells are from a morphologically distinct terrace 87 m a.s.1. in linncdalen, where we recently found a thin cover of an unambiguous basal till. the till cover demonstrates a glacial advance after the deposition of the shells and the terrace. therefore the mentioned lack of radiocarbon dates younger than 36,000 years could indicate that the area was ice covered from 36,000 to around 12,000 years b.p. hardly any reliable radiocarbon date from svalbard would contradict that assump tion, whereas it is in strong conflict with the amino acid data given below. amino acid analyses of the shells from the 8 7 m terrace yielded a mean total d/l value of 0.020 f 0.004 (bal-388. -673, -674, -677) for 8 individuals. such low values have not earlier been identified for shells from svalbard with a radio carbon age of more than 12.000 years (e.g. miller 1982; forman & miller 1984). the low d/l values provide strong constraints on possible diagenic temperature histories, and thus post-depo sitional sea level and glacial histories. mean annual temperature for the area today is close to -5°c; during ice-free periods in the weichselian it was probably much colder, whereas below glaciers and sea level it would be close to zero. for 10-12,000 year old shells which have been above sea level for most of the time, we have obtained a d/l value of 0.015 f 0.003 (n = 35). the till-covered 87 m terrace was deglaciated around 11,500 years b.p., and with a preceding ice cover of 5,000 years only, the shells would have had a d / l value of 0.020. for the rest of the period back to 36,000 (or more) years b.p. one must postulate such low temperatures (-20°c or lower) that essen tially no racemization took place. with the limitation that the d/l ratios are obtained from one locality only, they suggest that linncdalen was ice free for most of the period after 36,000 years b.p., and that this late weichselian ice dome was very short lived. as mentioned above, this reconstruction is appar ently in conflict with the missing radiocarbon dates for the period after 36,000years b.p. however. this might be explained by assuming a low relative sea level for most of that time, so that no shells are found within the present land area (boulton 1979; forman & miller 1984). the high relative sea level indi cated by the 8 7 m terrace requires the existence of a major barents sea ice sheet at the time of its formation, whether that occurred around 36.000 years b.p. or earlier. references andersen, b. g. 1981: late weichselian ice-sheets in eurasia and greenland. pp. 1-65 in denton. g. h. & hughes, t. h. (eds.): the lust great ice sheets. john wiley & sons, new york. boulton, g . s. 1979: glacial history of the spitsbergen archi pelago and the problem of a barents shelf ice sheet, boreas 8, 31-57. boulton. g. s . , baldwin, c. t . , peacock, j. d . , mccabe. a. m., miller. g . , jarvis. i . , horsefield, b., worseley, p., eyles, n., chroston. p. n., day. t. e.. gibbard, p.. hare, p. e. & von brunn, v. 1982: a glacio-isostatic facies model and amino acid stratigraphy for late quaternary events in spits bergen and the arctic. nafure 298, 437441. denton, g. h . & hughes, t . j . 1983: milankovitch theory of ice ages: hypothesis of ice-sheet linkage between regional insolation and global climate. quaternary reseurch 20, 125 144. denton, g. h., hughes, t. j. & karltn. w. 1986: global ice 278 j. mangerud et al. sheet system interlocked by sea level. quaternary research 26, 125-144. elverhdi, a . & solheim, a . 1983: the barents sea ice sheet a sedimentological discussion. polar research 1 n.s., 2 3 4 2 . elverhei. a , . lsnne. 0. & seland, r. 1983: glaciomarine sedimentation in a modern fjord environment. spitsbergen. polar research i n . s . , 127-149. fonnan. s. l . & miller, g . h. 1984: time dependent soil morphologies and pedogenic processes on raised beaches, brdggerhalveya, svalbard archipelago. arctic and alpine research 16, 381-394 landvik. j . y . , mangerud, j. & salvigsen, 0. 1987: the late weichselian and holocene shoreline displacement on the west-central coast of svalbard. polar research 5 n . s . , 29-44. mangerud. j . . elgersma. a , . helliksen, d., landvik, j . & salvigsen. 0. 1984: the late weichselian (25-10 ka b.p.) glacial maximum in lsfjorden and van mijenfjorden, spits bergen, svalbard. abstraca 13th annual arctic workshop. i n s t a a r , university of colorado, boulder, 67-68 mangerud, j . & salvigsen, 0. 1984: the kapp ekholm section, billefjorden, spitsbergen: a discussion. boreas 13, 15s158. miller. g . h. 1982: quaternary depositional episodes. western spitsbergen, norway: aminostratigraphy and glacial history. arctic and alpine research 14, 321-340. ohta, y. 1982: morpho-tectonic studies around svalbard and the northernmost atlantic. pp. 41-29 in ernbfy, a. f. & balkwill, h . r . (eds.): arctic geology and geophysics. canadian sociery of petroleum geologists memoir 8 . salvigsen, 0 . 1981: radiocarbon dated raised beaches in kong karls land. svalbard. and their consequences for the glacial history of the barents sea. geografika annaler 6 3 a , 2 w 291. svendsen, j . i . , landvik, j . y., mangerud, j. & miller, g . h. 1987: postglacial marine and lacustrine sediments in the lake linntvatnet, svalbard. polar research 5 n.s. (this volume). troitsky, l., punning, j-m.. hiitt, g . & rajamae, r. 1979: pleistocene glaciation chronology of spitsbergen. boreas 8, 401-407. vorren, t. 0. & kristoffersen, y. 1986: late quaternary glaciation in the south-western barents sea. boreas 15, 51 60. brachiopod zonation and age of the permian kapp starostin formation (central spitsbergen) koji nakamura, gakw kimura and t h o r e s. winsnes nakamura, k., kimura, g . & winsnes, t. s. 1987: brachiopod zonation and age of the permian kapp starostin formation (central spitsbergen). polar research 5 n.s., 207-219. this study has defined five brachiopod assemblage zones within the permian kapp starostin formation of festningen. central west spitsbergen. they are designated as the horridonin timanica zone. the waagenoconcha sp, a (gobbett 1964) zone, the megousia weyprechri zone, the pterospirifer ulatiis zone and the haydenella wilczeki zone in ascending order. only the lower three zones are recognized in thc same formation of sveltihel. the first zone, which is exactly equivalent to the ’spirifer limestone’ as well as the varingcn member of the kapp starostin formation, is probably kungurian in age. the last zone. situated near the uppermost portion of the hovtinden member, may possibly have a brachiopod assemblage matching that of the cvclolohus-bearing beds of the foldvik creek formation in central east greenland. consequently. the uppermost heds of the kapp starostin formation are chronologically dated as late permian, most probably as dzhulfian of the tethys province. koji nakamrtra, deparrmenr of g e o l o g y arid mineralogy. fucuiy of science, hokkaido university. siipporo. japan; g a k u kimura. g e o l o g y laborarory. faculty of educarion. kngawn u n i i i e r s i r ~ . takamalsu. jupan: tliore s. winsnes. norsk polarinsrirutr, rolfstnngveien 12. 1330 o s l o lufthaon. n o r w a y : january 1987 (revised august 1987). it has been well known for a long time that there is a debate among permian workers over the age of the ‘productus chertstones’, ‘brachiopod cherts’ and ‘spirifer limestone’ in the svalbard archipelago, in spite of the presence of rich and well-preserved megafossils including brachio pods, bryozoans, corals and sponges. this unsatis factory situation is attributed to the complete lack of ammonoids or fusulinids, which are more suitable for age determination, in those beds. the name tempelfjorden group was pro posed to replace the old terms of ‘brachiopod cherts’ and ‘spirifer limestone’, and the name kapp starostin formation was used rather restrictedly by cutbill & challinor (1965) for the marine permian distributed in the spitsbergen trough area. the most recent comments on the age of the uppermost beds of the tempelfjorden group were given by steel & worsley (1984) as: ‘there remains much uncertainty as to how far sequences assigned to the group extended into the late permian and opinions vary considerably: we indicate a ?kazanian age for the youngest beds and hope that studies of palynomorphs, con odonts and foraminifers now in progress may elucidate this problem’. on the other hand, vari ous ages have also been suggested since the 1900s for the lower border of the tempelfjorden group or the kapp starostin formation. in short, these two problems seem to be debatable even today. in 1984, a cooperative study between norsk polarinstitutt and hokkaido university, japan was undertaken in west central spitsbergen, the main objective of which was to obtain detailed stratigraphical and palaeontological information about the permian and the permian-triassic boundary. for these purposes, two stratigraphical sections of the kapp starostin formation exposed along the south side of isfjorden were measured both at festningen and at sveltihel, the latter being located about 60 km east of the former (fig. 1). study in japan led to the recognition that the brachiopod assemblage of the upper part of the kapp starostin formation was allied, as a whole, to that of the upper permian foldvik creek for mation in central east greenland. as a result, the more or less precise age of the uppermost beds of the kapp starostin formation could be deduced. stratigraphy as stated earlier, the name tempelfjorden group was introduced by cutbill & challinor (1965) 208 k. nakamura, g. kimura & t. s . winsnes fig. i . map 01 w u t h c r n spir,bcrscn 5 h o w n g t h c l o c a t i o n of festningun a n d svrltihul for marine late permian sequences exposed i n svalbard. according to them. this group com prised the kapp starostin formation in the spits bergen trough area, the tokrossaya formation on s ~ r k a p p ~ y a and 'spirifer limestone' on bjorn oya. t h e name miseryfjellet formation was later given to the 'spirifer limestone' on b j d r n ~ y a by worsley & edwards (1976). t h e type section designated by cutbill & challinor for the kapp starostin formation was festningen. central west spitsbergen. a three-fold division of the kapp starostin formation was further proposed by them. i n which they delineated in ascending order the vbringen, svenskeegga and hovtinden members. a . festrlirlgen section the schematic section simplified from the detailed column measured by the japanese members at festningen is given in fig. 7 . the kapp starostin formation is about 400 m thick and can be classi fied into 12 lithologic w i t s . at its base the vcwin gen member, formerly called 'spirifer limestone' or 'limestone a' ( g e e et al. 1952), is composed of only o n e lithologic unit (unit 1) which is made u p of white coarse limestones in the lower part and grey marly limestones in the upper, and is dominated by brachiopod fossils and accom panied by a lesser number of bryozoans, corals and so o n . the voringen member is overlain by the svenskeegga m e m b e r , which contains units 2 , 3 , 4 and 5. a m o n g these, units 2 4 are made u p of clastic rocks, such as sandstone, shale and chertstone, and a r e very poor in organic remains. unit 2 is characterized by the inclusion of cal careous nodules at several horizons. t h e upper most unit 5 consists mostly of light-grey bedded limestones and is prolific in megafossils, such as brachiopods, corals, bryozoans and sponges. t h e hovtinden member may b e better sub divided into lower, middle and upper beds. units 6 8 a r e included in the lower bed. of which units 6 and 7 consist lithologically of shales and chertstones, while unit 8 consists of limestone. brachiopods were collected from several horizons of units 6 and 7. unit 8 is marked by a sudden increase of large brachiopods and bryozoans, to which corals and sponges are associated. the middle bed is composed of unit 9, represented by shales with a few brachiopods and pelecypods in its upper part. and unit 10, consisting mostly of limestones rich in brachiopods and bryozoans. the upper bed comprises units 11 and 12 and is composed mostly of shales. a glauconitic sand stone layer was observed in unit 11, while some nodular limestone lenses are intercalated in unit 12. brachiopods and corals were found in unit 1 1 . and some sponge remains were collected from the uppermost beds of unit 12. b . sueltihel section the kapp starostin formation outcrop a t svelt ihel was briefly described by gobbett (1964) and by major & nagy (1972). t h e formation measured about 340 m in thickness and was litho logically divided into 11 units. as shown in fig. 3. the vqringen member, corresponding to unit 1, is composed mostly of limestones and sandy limestones. and it yielded numerous brachiopods together with some bryozoans, corals and sponges. as at festningen. t h e svenskeegga member is represented by units 2, 3 and the lower half of unit 4, all of which are made up of i t e m p e l f j o r d e n g r o u p f o r m a t i o n k a p p s t a r o s t i n h 0 0 w 0 0 n d 0 ? , i ho ri zo n 0 0 0 1 h o rr id o n id ti m a n ic a st u c k en b er g 2 h o rr id o n ia g r a n u li fe r a (t o u l a ) 3 c h a o ie ll a n e o in fl a ta (l ic h a fs w ) 4 m u iw o o d ia m a m a ta (k ey se rl in g) 5 n e o s p ir if e r g ro n w a ll i d u n ba r 6 d n e m n a r ia p se u d o h o rr id a (w im an ) 7 s p ir if e r e ll a d ra sc h e i (t o u la ) 8 m u iw o o d ia d u p le x (w im a n ) 9 w a a q en o co n ch a w in n n i sa r y tc h ev a 1 0 w a a ye n o co n ch a sp . a (g d b b e t t ) 1 1 c le io th y ri d in a p e c ti n if e r a (d ‘ o r b ig n y ) 1 2 c le io th y ri d in a k o tl u k o v i st e p a n o v 1 3 u c h a re w ia s p it sb e rg ia n a g o b b et t 1 4 n e o s p ir if e r s tr io -p a ra d o x u s (t o u la ) 1 5 w a a g en o co n ch a p a y e ri (t o u l a ) 1 6 m e y o u si a w e y p re c h ti (t o u l a ) 17 s tr e p to rh y n c h u s k e m p e i a n d er ss o n 18 m u ir w o o d ia y re e n la n d ic a d u n ba r 1 9 s te p a n o v ie ll a c u rv a ta (t o lm a c h ev ) 20 l ic h a re w ia w im n i w b b e t t 2 1 t h u le p ro d u c tu s c r a s s a u r it u s sa r y tc h ev a a nd w a te r h o u se 22 p te r o s p ir if e r a la tu s (s c h l o t h e im ) 2 3 p le u ro h o rr id o n ia s c o re sb y e n si s d u n ba r 24 c h o r is ti te s s m d e rb e rq h i d u n ba r 25 o d o n to sp ir if e r m ir a b il is d u n ba r 26 l io s o te ll a sp it zb e rg ia n a (t 0u l. a ) 27 l ic h a re w ia sp . 28 p a e c k e lm a n n ia to u la i d u n ba r 29 k o c h ip ro d u c tu s p le x ic o s ta tu s d u n ba r 30 m eg o u si a y a k u ti c a (l ic ha re w) 31 h a y d e n e ll a g e fo e n s is (l ic h a r e w ) 3 2 h a y d e n e ll a w il c z e k i (t o u la ) ho vt in de n mb. 1 mi dd le i u p p er lo we r /# ri n g e n m b. sv en sk ee gg a m -b . m e g o u sl a p te r o s p ir h a yd en e lwaage noconc hasp’* ‘. i w e v d re c h ti 7.. i al a tu s zi w il c . tl b sha le 0 sand st on e ch er ts ta ne n o d u le 1 7 18 20 2 1 2 8 30 3 1 .’ 32 i f ig . 2 . r an ge c ha rt o f th e br ac hi op od s of t he k ap p st ar os ti n fo rm at io n at f e st n in g e n , c cn tr al w cs t sp it sb er ge n t e m p e l f j o r d e n g r o u p k a p p s t a r o s t i 11 f o r m a t i o n ' \ \ \ \ ', ' \ h o r i z on 1 y a k o v le v ia i m p re ss a (t o u l a ) 2 h o rr id o n ia ti m a n ic a s t u c k e n b e r g 3 h o rr id o n ia q ra n u li fe ra (t o u l a ) 4 w a a g en o co n ch a i r q in a e ( st u c k e n b e r g ) 5 c h a o ie ll a n e o in fl a ta (l ic h a r e w ) 6 n e o sp ir if e r q rd n w a ll i d u n b a r 7 s p ir if e r e ll a p o la r is w im a k 8 d th y r is a m d ru p i d u n b a r 9 c a n c ri n e ll a te n u is si m a g o b b e t t 10 c a n c ri n e ll a sp . 1 1 c le io th y ri d in a p e c ti n if e r a (d 'o r b ig n y ) 1 2 a n em o n a ri a p se u d o h o rr id a (w im an ) 1 3 w a a q en o co n ch a s p . 1 4 p a e c k e lm a n n e ll a s p . 1 5 c le io th y ri d in a k o tl u k o v i st e pa n o v 1 6 l ic h a re w ia c fr . sp it sb e rq ia n a g o b b e t t 1 7 s p ir if e r e ll a s a ra n a e (v e r n e u il ) 18 a n id a n th u s a a q a rd i (t o u l a ) 1 9 n e o sp ir if e r c fr . st ri o -p a ra d o x u s (t o u la ) 2 0 m eq o u si a w e y p re c h ti (t o u l a ) 2 1 k o c h ip ro d u c tu s p le x ic o s ta tu s d u n b a r 22 l io s o te ll a d e li c a tu la d lj n ba r 2 3 k ro to v ia sp . 24 n e o sp ir if e r s? . 25 l in g u la fr e b o ld i g o b b e t t n w 0 0 0 0 p r' iw / c i i n rn m b. 1 h o v ti n d e n m b* i l o w e r v d ri n g e n m b. s v e n sk e e g g a i i l im e s to n e s h a le 1-1 c o n g lo m e ra te 1 1 10 9 il 16 17 18 l 19 20 i m id d le u p p e r eq ou sih ---7 "'i 23 2 5 2 4 a f ig . 3 . r an ge c ha rt o f th e br ac hi op od s o f th e k ap p st ar os ti n f or m at io n at s ve lt ih el . c en tr al s pi ts be rg en . brachiopod zonation 211 the horridonia timanica zone is the lowest zone, characterized particularly by the abundance of productoid brachiopods including horridonia timanica, h . granulifera, yakovleuia impressa, waagenoconcha irginae, muirwoodia mammata, and chaoiella neoinflata. other notable species are neospirifer gron walli, spiriferella polaris and s. draschei. the absence of yakouleuia impressa at festningen is noteworthy. this may be due to environmental control. the waagenoconcha sp. a (gobbett) zone is established with the vertical distribution of the named species from unit 4 to the lower half of unit 7 at festningen. other diagnostic species of this zone are muirwoodia duplex, waagenoconcha wimani and cleiothy ridina kotlukoui. special attention should be paid to the first appearance of a characteristic late permian genus licharewia in the lower part of the equivalent of this zone at sveltihel. the megousia weyprechti zone is clearly delineated both at festningen and sveltihel. megousia weyprechti, waagenoconcha payeri, muirwoodia greenland ica, stepanoviella curuata, licharewia wimani, streptorhynchus kempei, and thuleproductus crassauritus are confined to this zone, as far as our collection is concerned. gobbett (1964). how ever, described streptorhynchus kempei from the ‘spirifer limestone’ of spitsbergen. the ptero spiriferalatus zone is identified only at festningen and is characterized by the following species: pterospirifer alatus, pleurohorridonia scoresby ensis, choristites sdderberghi, odontospirifer mirabilis, liosotella spitsbergiana, and paeckelmannia toulari. several species from the megousia weyprechti and pterospirifer alatus zones are common to those described from the foldvik creek formation in central east green land. the haydenella wilczeki zone lies within the uppermost zone, and diagnostic species of this zone are haydenella wilczeki and h . gefoensis. this zone has been recognized only at festningen. there may be several possible reasons for the remarkable stratigraphical changes in brachiopod assemblage recognized within the kapp starostin formation. malkowski & hoffman (1979) sug gested that the presence of some changes in rela tive water depth probably originated from the sea level change during the interval of deposition of the kapp starostin formation, based on the analysis of the lithofacies and biofacies. this seems to be one of the reasons for the above mentioned changes of the brachiopods. it is noteworthy, however, that the same bio various kinds of clastic rocks. brachiopods were only found in unit 4. all beds from the upper half of unit 4 to unit 11 may be included in the hovtinden member, and they are mostly com posed of altered cherts with thin limestone as well as shale layers, except for the uppermost unit 11 represented by glauconitic sandstones. amongst these units, units 5 and 6 contain several layers yielding brachiopod remains. brachiopod zonation stepanov (1957) considered that the brachiopod fauna of the whole ‘brachiopod cherts’ repre sented only one period, and he proposed a sval bardian stage for them. gobbett (1964) basically followed stepanov’s view in this and wrote: ‘the brachiopods described by frebold (1937) from 23 horizons facilitate a three-fold division of the section (forbes et al. 1958). however, these three groups of species are based on collections which are small and poorly-preserved in comparison with those from inner isfjorden. extensive col lecting from the brachiopod chert, including the spirifer limestone, shows that the brachiopod fauna of this formation is essentially uniform.’ according to our own examination, however, brachiopod assemblages vary considerably from horizon to horizon, apart from the presence of a few long-ranging species, as shown in fig. 2. so we support frebold (1937). most of the brachio pod species collected from the voringen member (unit 1) are of early permian forms, while late permian ones are enumerated in unit 5 of the svenskeegga member and in units 8, 10 and 11 belonging to the hovtinden member. five brachiopod zones are recognized within the kapp starostin formation of festningen as the hor ridonia tirnanica zone. the waagenoconcha sp. a (gobbett 1964) zone, the megousia weyprechti zone, the pterospirifer alatus zone and the hay denella wilczeki zone from old to young, on the basis of the vertical distribution of brachiopod species. the horridonia timanica and megousia wey prechti zones are also recognized at sveltihel (fig. 3). the occurrence of cleiothyridina kot lukovi and anemonaria pseudohorrida in unit 4 and its stratigraphical position at sveltihel strongly suggest that this unit may correspond to unit 5, the lower part of the waagenoconcha sp. a zone at festningen (fig. 4). 212 k . nakamura, g. kimura d t . s. winsnes 300 ! o o 100 0 r; s c m c .r( !+ 3 . . , \ . -.---- stratigraphical relations in brachiopod assem blage are basically traceable i n the counterparts of the kapp starostin formation in central east greenland, specifically in the foldvik creek for mation. and in ellesmere island, as well as in the assistance and trold fiord formations (liao pers. comm. 1986). this means that the vertical changes of brachiopod assemblages in the kapp f i g . 1. correlation ot t h e hrarhiopod zones between fest ninge n m d svel t i hel, starostin formation are not locally restricted only to the spitsbergen trough a r e a , but a r e also extended to the other parts of the boreal sea areas. therefore, the brachiopod zonation pre sented here undoubtedly has a chronostrati graphical significance and has a n effect on correlation between the permian sequences dis tributed in the boreal sea areas. brachiqvod zonation 213 correlation with east greenland the tethyan permian sequences usually contain abundant ammonoids, fusulinids, conodonts and brachiopods that are useful for international cor relation and age-determination. so a correlation of the kapp starostin formation with rocks of the tethys could be expected. at present, however, this is impossible with any certainty using palaeontological means. there are two major reasons for this difficulty: (1) neither ammonoids nor fusulinids have been discovered in the kapp starostin formation, and the occur rence of conodonts is rare and confined to the voringen member, which comprises the lowest beds of the formation: (2) the brachiopod fauna in the kapp starostin formation has very little similarity to corresponding faunas in the tethys. nevertheless, we have a reasonably satisfactory method by which the relative age of the kapp starostin formation may be determined. this relies upon brachiopod correlation of the kapp starostin formation with the more precisely aged upper permian of greenland, already dated by the ammonoid godthatihites kullingi. gobbett (1964) argued that the permian of central east greenland belonged to the upper most part of the permian and was thus con siderably younger than the svalbardian, which was actually represented by the ‘spirifer lime stone’ and ‘brachiopod cherts’ (now the kapp starostin formation). we do not accept this, but propose that the upper half of the hovtinden member of the kapp starostin formation is mostly contemporaneous with the foldvik creek formation in central east greenland, while the voringen member of the formation agrees in age with the upper part of the upper marine group (from g-300 to h-119) of northeast greenland, based on the high degree of similarity of brachiopods. as far as the brachiopods from east greenland are concerned. n o new systematic contributions have been made since dr. dunbar’s papers appeared in 1955 and 1962. therefore, we are now obliged to reproduce four old sections pro vided with brachiopod information, in order to discuss correlations between spitsbergen and greenland (fig. 5 ) . one of them is from amdrup land of northeast greenland (dunbar 1962), while the remaining three are from scoresby land, kap stosch, and clavering 8 of central east greenland (maync 1942; dunbar 1955). the upper part of the upper marine group (now known as mallemuk mountain group) of north east greenland roughly corresponds to the hor ridonia timanica zone (‘spirifer limestone’) of spitsbergen, based on the mutual occurrences of some diagnostic species, notably yakouleuia impressa, athyris amdrupi, neospirifer gronwalli, chaoiella neoinflata, and horridonia granulifera. the upper limit of this group might be cut by the present topographical surface, consequently the equivalent beds to the upper half of the kapp starostin formation are not presented in this area. as a matter of fact, no definite late permian faunal elements have been found in northeast greenland, although hbkansson & stemmerik (1984) suggested the presence of a highly diverse late permian fauna in peary land. in central east greenland the marine beds of the foldvik creek formation rest on non-marine beds or directly on metamorphic basement and are believed to be late permian in age. on account of the occurrence of an ammonoid genus g o d t haabites in their upper part. the formation is composed of limestones, dolomites. ‘productus limestone’, martinia limestone or shale, posi donia shale. in addition to gypsum and red con glomerate beds. even though rapid lateral changes in lithofacies are characteristic and the marine members are in part intertonguing and coeval, two brachiopod zones can be strati graphically discriminated within this formation, that is, lower fossil i zone and upper fossil i1 zone. the brachiopods found in those two zones justify a firm correlation of the fossil i zone and the fossil i1 zone to the upper part of the megousia weyprechti zone and the pterospirifer alatus zone of spitsbergen, respectively. the fos sil i zone in greenland and the upper part of the megousia weyprechti zone in spitsbergen share relatively distinctive forms as streptorhynclzia kempei, waagenoconcha payeri and miiirwoodia greenlandica. on the other hand, the fossil i1 zone is easily compared with the pterospirifer alatus zone. on the basis of the mutual occur rences of pterospirifer alatus, pleurohorridonia scoresbyensis, choristites s@derberghi and o d o n tospirifer mirabilis. at the schucherts flod valley of scoresby land the fossil i zone is not devel oped, while the fossil i1 zone is lacking at river 14, east of kap stosch, although the elements of the fossil i1 zone are unesrthed together with those of the fossil i zone from the ‘white block’ derived from the underlying beds to be included "i a a a @a permian i group tempelfjorden k~pp staros t in formation mallemuk mountain group 1 i ass 1c foldvik creek forniatlon brachiopod zonation 215 mertonberget, chydeniusbreen, n y friesland. on the other hand, specimens of licharewia wi mani were not figured by gobbett. he proposed this new species from the specimens figured by wiman (1914) from lovenberget, ny friesland. cutbill (1968) tentatively correlated the beds from which wiman collected brachiopods on lovcn berget to the svenskeegga member in west and central spitsbergen. consequently, there seems to be a considerable uncertainty regarding the precise stratigraphical occurrence of this genus in n y friesland, northeast spitsbergen. actually, we did not find licharewia in the v ~ n n g e n mem ber, but found it in both the svenskeegga and hovtinden members of the surveyed area. according to gobbett (1964), the following species were common between the svalbardian stage and the upper permian foldvik creek for mation in central east greenland: krotouia lich arewi, horridonia timanica, streptorhynchus kempei, neospirifer strio-paradoxus, spiriferella keilhauii, spiriferellina cristata and craspedalosia pulchella. of these, the first species was only found in the overlying beds of the ‘spirifer lime stone’, and the remaining six were described by the finder from the ‘spirifer limestone’. however, the specific identification of sowerbina maynci described from the foldvik creek for mation by dunbar (1955) with horridonia timan ica is very questionable. streptorhynchus kempei and neospirifer strio-paradoxus are more abun dant in the hovtinden member than in the v0rin gen member of central spitsbergen. spiriferella keilhauii and spiriferellina cristata are relatively long-ranging species. the occurrence of cras pedalosia pulchella in the ‘spirifer limestone’ or the tokrosscbya formation is noteworthy, because the age of this species is well dated to late permian, and it has been known to occur from the lower kazanian of the kanin peninsula, ussr (stepanov et al. 1975), in addition to the occur rence in the fossil i zone at forposten on cla vering 8 , central east greenland. in svalbard, specimens assigned to this species were, according to gobbett (1964), detected from the misery fjellet formation (‘spirifer limestone’) of b j ~ r n ~ y a , the tokross0ya formation of s~rkappbya and the ‘spirifer limestone’ on the pyramiden summit in dickson land. the miseryfjellet for mation of bj0rncbya and the tokross~ya for mation of smkappoya may partly include upper permian sediments (cutbill & challinor 1965), and there is considerable doubt regarding the in the triassic otoceras zone. the foldvik creek formation near the southern coast of clavering p, is provided with both. the occurrence of an ammonoid godthaabites just above the fossil i1 zone is noteworthy. the godthaabites-bearing beds may be equivalent stratigraphically to the haydenella wilczeki zone, uppermost brachiopod zone of the kapp starostin formation. age assignment the age of the kapp starostin formation, based mainly on brachiopods that are common to spits bergen and the ussr, has been assigned dif ferently by many workers. the lower boundary of the formation has been regarded as ranging from sakmarian to ufimian in age, and the upper from sakmarian to latest permian. age of the lowest beds of the kapp starostin formation malkowski & szaniawski (1977) were greatly impressed by the supposed leonardian affinities of the conodonts collected from the voringen member in polakkfjellet (torell land) and the hornsund regions. on the other hand, sosi patrova (1967) and stepanov (1967) considered the lowest boundary of the formation to be kun gurian in age, based on foraminifers and brachio pods, respectively. further, burov et al. (1965) and ustritsky (1971), using brachiopods, con sidered the formation only to have started after the kungurian. among these opinions, it should be noted that a conflicting age has been given to the brachiopod assemblage of the lowest beds of the ‘brachiopod cherts’ (= ‘spirifer limestone’) and the kapp starostin formation (= v ~ r i n g e n member). the presence of licharewia and several species com mon to the upper permian foldvik creek for mation of central east greenland in the ‘spirifer limestone’ strongly denotes a late permian age for the lowest beds of the kapp starostin forma tion. gobbett (1964) described two species of licharewia, l. spitsbergiana and l. wimani from the ‘spirifer limestone’ of ny friesland, north east spitsbergen. the presence of licharewia in the ‘spirifer limestone’ is important, because this genus is unknown in the lower permian of the ussr or elsewhere. licharewia spitsbergiana was described only from the ‘spirifer limestone’ on 216 k. nakamura, g. kimura & t. s . winsnes stratigraphical position of the beds from which specimens were collected o n t h e pyramiden sum mit. in short, the stratigraphical occurrence of craspedalosia pulchella in svalbard is also rather uncertain. on the other hand. the occurrence of such species as horridonia titnanica, neospirifer gron walli, waagenocoticha irginae, spiriferella dra schei and yakovleuia inipressa from the veringen member indicates the kungurian age of the member. ivanova (1972) described horridonia timanica, yakouleuia inipressa, waagenoconcha irginae and spiriferella draschei from the late artinskian talatinsk formation and the kun gurian lekborkisk formation of pechora, ussr. kulikov (1974) listed horridonia timanica, neo spirifer griin walli. waagetroconchu irginae and spiriferella cf. draschei from the kungurian of the urals. although a general uncertainty relating to the specific identification and t o the strati graphical range of these species may exist, these occurrences strongly suggest the kungurian age for the lowest beds of the kapp starostin forma tion. i t thus appears that yakovleuia impressa is restricted to the early permian in the ussr and that it is one of the most important species for the correlation of these rocks. a n important matter t o decide is whether the v ~ r i n g e n member is early permian or late permian in age. i n this paper, the age of the member is tentatively esti mated to be early permian, in a two-fold division. based more on the occurrence of yakouleuia impressa than the uncertain occurrences of lich arewia and craspedalosia pulchella. however. further study is required. a g e of the uppermost beds of the k a p p starostin formation recently, most authors presumed the age of the uppermost beds of the kapp starostin formation to be early kazanian. because the brachiopods from the upper part of the formation indicated a close relationship with the kazanian of the ussr. in this respect, the youngest age assumption was offered by cutbill & challinor in 1965. who main tained that the formation represented the kun gurian and the whole u p p e r permian, but without presenting any palaeontological evidence. w e are most concerned that the age of the upper border of the kapp starostin formation should be dis cussed more precisely. for this purpose, a critical evaluation of ptero spirifer alatus, o n e of t h e diagnostic species of the lower zechstein, is first taken into consideration. the occurrence of this species is restricted o n spitsbergen to the middle bed of the hovtinden member of the kapp starostin formation and in greenland to the fossil i1 z o n e of the foldvik creek formation. quite recently, dr. kozur of the hungarian geological institute contributed very important comments t o t h e newsletter no. i1 of scps (subcommission o n permian strati graphy), dealing with the age of the zechstein in the germanic basin. he pointed out that the base of the zechstein lay in the upper abadehian, and it was not far from t h e dzhulfian base in the tethys. if this assumption is correct. either the middle bed of the hovtinden member or the fossil i1 z o n e of the foldvik creek formation is reasonably dated t o late permian, in a threefold division. the discovery of this species has been reported from the lower permian of china (ding & qi 1983) and the lower kazanian of the baltic province of ussr (suveizdis 1984). however, the chinese specimen figured seems too poorly preserved to make a specific identification, while the russian specimen has not been described or figured. as described earlier, the uppermost brachio pod zone of the k a p p starostin formation, t h e haydenella wilczeki z o n e a t festningen is exactly correlated to the upper part of the martinia lime stone including an ammonoid godthaabites at clavering 8. central east greenland. most ammonoid workers regard godthaabites as syn onymous with cyclolobus except for waterhouse (1972) and zakharov (1983). t h e stratigraphical distribution of cyclolobus and codthaabites is shown in table 1. they a r e mostly confined to rocks of abadehian-dzhulfian ages in the tethys faunal realm. t h e highest horizon of the re presentatives of these genera so far known is the upper dzhulfian vedioceras zone in trans caucasia, except for the occurrence in the upper most permian of t h e kitakami mountains, japan (ehiro & bando 1985). although the cyclolobus bearing horizon in the kitakami mountains is thought t o be changhsingian or dorashamian in age, there does appear to be some doubt. a s pointed out by balme (1979), teichert & kummel (1976) discussed these matters in detail and then accepted the view of furnish (1966) that t h e pres ence of cyclolobus indicated a post-guadalupian age for the martinia limestone in central east greenland. brachiopod zonation 217 3 10 i z 4 0 j 0 m 218 k. nakamura, g. kimura & t . s . winsnes in short, the uppermost beds of t h e kapp sta rostin formation of festningen a r e estimated with high possibility t o be late permian in age and most probably to be dzhulfian. kotljar (1984) presented a synopsis of t h e correlation of the permian between the urals and tethys in which she correlated the tatarian stage of the former to the whole of the upper midian, dzhulfian. and dorashamian of the latter, as shown in table 1 . if this correlation is acceptable, the kapp starostin formation lies within the interval from late kun gurian to early or even early late tatarian of the russian permian standard. conclusion the kapp starostin formation commencing with the ‘spirifer limestone’ is about 4 0 0 m thick at festningen and about 3 4 0 m at sveltihel, west spitsbergen. taking into account the strati graphical and palaeontological evidence, the fol lowing conclusions may be introduced with regard to the k a p p starostin formation: a ) five brachiopod zones are identified within the formation: they a r e the horridonia timanica zone. the waagenoconcha sp. a (gobbett 1964) z o n e , the megoiisia wevprechti z o n e , the ptero spirifer alatiis z o n e . and the haydenella btdczeki zone in ascending order. b) the basal part, that is. the ‘spirifer lime stone‘. is contemporaneous with the uppermost part of the upper marine g r o u p (mallernuk mountain group) in the holm land and a m d r u p land areas of northeast greenland. based on the mutual occurrences of some diagnostic brachio pod species. probably indicating a kungurian age. c) the upper part of the k a p p starostin for mation, represented b y the upper three zones. roughly corresponds to the permian foldvik creek formation in central east greenland. d) two brachiopod zones are recognized in the foldvik creek formation. t h e lower zone (fossil i z o n e ) is contemporaneous with the megoiisia weyprechti zone. and t h e upper o n e (fossil i1 z o n e ) with the pterospirifer alatus zone of west spitsbergen. the occurrence of an ammonoid godthaabires or c~clolobiis just above the upper fossil i1 z o n e in central east greenland is note worthy. as a result. the haydenella wilczeki zone in the kapp starostin formation can be strati graphically correlated with the godthuabites bearing beds in central east greenland. and must consequently b e post-guadalupian (most prob ably dzhulfian) in age. e ) in conclusion, we recommend the kapp sta rostin formation at festningen, yielding ample and various kinds of fossils, as the standard sec tion of the middle-upper permian in the arctic region. the uppermost permian (changhsingian o r dorashamian) may, however, be missing. acknowledgements. the authors would like to thank odd rogne. director of norsk polarinstitutt, and professor emeri tus tatsuo tatsumi (university of tokyo) who organized and directed this cooperative work on spitsbergen. during the stay in oslo and on spitsbergen, nakamura and kimura were extended numerous courtesies by the staff of norsk polarinstitutt; they are particularly indebted t o 0rnulf lauritzen, dr. yoshihidc ohta. thor siggerud and kbre bratlien for con sultations and advice on the preparation of the field work. atlc m ~ r k of the continental shelf institute, norway, kindly afforded facilitics for transportation by boat from festningen to sveltihel. ayumu ohta accompanied the japanese expedition party o n spitsbergen and helped us in various ways. drs. j . m. dickins (bureau of mineral resources, australia), n . archbold (commonwealth scientific and industrial research organization. australia), yu. zakharov (far-eastern scientific centre. ussr). j . m. hurst (geological survey of greenland. denmark). z. liao (nanjing institute of geology and palaeontology. people’s republic of china) and 14. kozur (hungarian geological institute. hungary) provided various important information on the permian stratigraphy and palacontology . the project could not have been undertaken without financial support from the polar research committee of kyoikusha co. ltd. in tokyo. without their help and interest the completion of this study would h a w been impossible. to all mentioned above. the authors are extremely grateful. references balme. b. e. 1979: palynology of permian-triassic boundary beds at kap stosch. east greenland. meddr. grmnlarid 200 (61. 1-37, 3 pls. burok. ju. p.. gavrilov. b. p.. klubov. b . a , , pavlov, a. p. 8: ustrickij, v . i . 1965: novye dannye o verchnepermskich otloienijach spicbergena (new data on upper permian deposits of spitsbcrgen). material? po geologii spicherpia, n l l g a . 112-126. cutbill. j. l . 1968: carboniferous and permian stratigraphy of ny frirsland. spitsbcrgen. norsk polarinst. a r h o k 1966.12 24. cutbill. j . l. & challinor. a . 1%s: revision of the strati graphical scheme for the carboniferous and permian rocks of spitsbergen and b j b r n ~ y a . geol. mag. 203 (5). 418-439. ding. p. z . 8: qi. w . t 1983: phyllum brachiopoda (car boniferous and permian). pp. 244-425 in xian institute of geology and mineral resources etc. (eds.): palaeo~rro/ogica[ ailas of northwest chino 2. sciencc press, peking (in chinese). brachiopod zonation 219 dunbar. c. 0. 1955: permian brachiopod faunas of central east grcenland. meddr. grenland 110 ( 3 ) . 1-169. 32 pis. dunbar, c . 0. 1962: faunas and correlation of the late paleo zoic rocks of northeast greenland. part 111 brachiopoda. meddr. gr(ti1and 167 (6). 1-14, 2 pls. ehiro. m. & bando, y . 1985: late permian ammonoids from the southern kitakami massif, northeast japan. trans. proc. palaeont. sac. japan. n.s. 137, 25-49, 3 pls. forbes, c. l., harland, w. b. & hughes, n . f. 1958: palae ontological evidence for the age of the carboniferous and permian rocks of central vestspitsbergen. geol. mug. 95 ( 6 ) , 465-490. frebold, h . 1937: das festungsprofil auf spitsbergen iv. die brachiopodenund lamellibranchiatenfauna und die strati graphie des oberkarbons und unterperms. skr. sualbard og ishavet 69, 1-94, taf. 1-11. furnish. w. m. 1966: ammonoids of the upper permian cvclo lobus-zone. neues jahrb. grologie palaontologie, abh. 125, 265-296. pl. 23-26. gee, e. r.. harland. w. b . & mcwhae. j. r. h. 1952: geology of central vestspitsbergen: part i: review of the geology of spitsbergen with special reference to ccntral vestspits bergen. part 11: carboniferous to lower pcrmian of bille fjorden. trans. roy. soc. edinb. 62. 299-356. gobbett. d. h . 1964: carboniferous and permian brachiopods of svalbard. norsk polarinst. skr. 127. 1-201. 25 pis. hikansson, e. & stemmerik, l. 1984: wandel sea basinthe north greenland equivalent to svalbard and the barents shelf. pp. 97-107 in petroleum geology of the north euro pean margin. norwegian petroleum society (graham & trotman ltd.). iranian-japanese research group 1981: the permian and the lower triassic systcm in abadeh region. central iran. mem. fac. sci., kyoto unio., ser. geol. mineral. 47 ( 2 ) , 61-133, 6 ivanova, v. v. 1972: permskie brachiopody pecorskogo bas sejna (permian brachiopods of the petora basin). pp. 72-161 in ivanova. v. v. & semenova. e . g.: srednekamennou gol'nye i permskie brachiopody vostoka i seoera evropejskoj casti sssr (middle carboniferous and permian brachiopods of the east and north of the european part of the ussr) nauka, moskva. kotljar, g . v. 1984: korreljacija stratigrafieeskich skal perm skich otloienij biarmijskoj teticeskoj i angarskoj oblastej (correlation of stratigraphic scales of permian deposits of the biarmian tethyan and angarian area). osnovnye cerfy strarigrafii permskoj sistemy sssr. trudy nouuja serija 286, 229-233. kotljar, g . v . , zacharov, ju.d., koeirkevie, b. v. el al. 1983: pozdnepermski ttup tvoljucii organiteskogo mira: diul'fnskij i dordamskij jarusy sssr (late permian phase of evolution of the organic world: the dihulfian and the doragamian stage of the ussr). 2oopp. kulikov, m. v. 1974: brachiopody kungurskogo jarusa urala (brachiopods of the kungurian stage of the urals). trudy f r l ta geol. i geochimii ural'skogo nauc. centra a n s s s r 109, 77-123. major, h. & nagy, j. 1972: geology of the adventdalen map area with a geological map, svalbard c9g 1: 100000. norsk polarinst. skr. 138, 1-58. malkowski. k. & hoffmann. a. 1979: semi-quantitative facics model for the kapp starostin formation (permian), spits bergen. acta palaeont. polon. 2 4 , 217-230, pl. 2-3. pis. malkowski, k. & szaniawski, h . 1977: permian conodonts from spitsbergen and their stratigraphic significancc: a preliminary note. norsk polarinst. h b o k 1975, 79-84. 1 pl. maync, w. 1942: stratigraphie und faciesverhaltnisse der ober permischen ablagerungen ostgronlands zwischen wouaston forland und dem kejser franz josephs fjord. meddr. grgn land 115 (21, 1-128. 6 pls. minato, m., kato, m.. nakamura, k., hasegawa. y . . choi. d. r. & tazawa. j. 1974: biostratigraphy and corrclation of the permian of japan. jour. frc. sci., hokkaido unio.. ser. 4 , i 8 (2-2). 11-47, nakazawa, k., kapoor, h . m., ishii, k., bando, y.. okimura. y . & tokuoka, t. 1975: upper permian and the lower triassic in kashmir. india. mem. fac. sci., kyoto unio., ser. geol. and mineral. 47 ( i ) , 1-106. 12 pls. pakistani-japanese research group 1985: permian and triassic system in the salt range and surghar range, pakistan. pp. 221-312 in nakazawa, k. & dickins. j . m. (eds.): 'the tethys'. her paleography and paleobiography from paleozoic ro mesozoic. tokai univ. press. 14 pls. sosipatrova. g . p. 1976: verchnepaleozojskie foraminifery spic bergena (upper palaeozoic foraminifera of spitsbcrgen). materialy srratigraf. spicbergena, n l l g a , 94-120. steel, r . j . & worsley, d. 1984: svalbard's post-caledonian strata an atlas of sedimentational patterns and palaeo geographic evolution. pp. 109-135 in petroleum geology of the north european margin. norwegian petroleum society (graham & trotman ltd.). stepanov, d . l. 1957: orlovom jaruse permskoj sistemy arktiki (on a new stage of the permian system of the arctic). vestnik l g u , ser. geol. i geogr. 24 (4). 2lk24. stepanov. d . l . 1967: sval'bardskij jarus i ego poloienie v stratigrafifeskoj skale permskoj sistemy (the svalbardian stage and its position in the stratigraphic scale of the permian system). sovetskaja geologija 2 . 3-18. stepanov. d. l.. kulikov. m. v. & sultanaev, a . a. 1975: stratigrafija i brachiopody verchnepermskich otloieni j poluo strova kanin (stratigraphy and brachiopods of the upper permian deposits of the kanin peninsula). vestnik lenin gradskogo unioersiteta 6. 51-65. suvejzdis, p. i. 1984: pribaltijskaja provincia, regional'naja stratigrafija (the baltic province, regional stratigraphy). trudy, novaja serija 286, 105-111. teichert, c. & kummel. b. 1976: permian-triassic boundary in the kap stosch area. east greenland. meddr. grrnnland 197 ( 5 ) . 1-54, 16pls. ustrickij, v. 1. 1971: biostratigrafija verchnego paleozoja ark tiki (biostratigraphy of the upper palaeozoic of the arctic). niiga, trudy 164. 278 pp. waterhouse, j . b. 1972: the evolution, correlation and paleo geographic significance of the permian ammonoid family cyclolobidae. lethaiu 5 ( 3 ) . 251-270. wiman, c: 1914: uber die karbonbrachiopoden spitsbergens und beeren eilands. nova acta sac. sci. uppsala. ser. 4. 3 18). 1-92. taf. 1-19. worsley, d. & edwards, b. 1976: the upper paleozoic suc cession of b j ~ ~ n d y a . norsk polarinst. arbok 1974, 17-34. zacharov, ju.d. 1983: novye permskie ciklolobidy (gon iatitidae) juga sssr (new permian cyclolobids (goniatitidae) of the south of the ussr). paleontologiteskij furrial 2. 1 2 6 130. por_024.fm 152 polar research 26 2007 152 – 159 © 2007 the authors on the double-diffusive and cabbeling environment of the arctic front, west spitsbergen finlo r. cottier & emily j. venables scottish association for marine science, dunstaffnage marine laboratory, oban, argyll, pa37 1qa, uk abstract this paper describes the thermohaline characteristics of the arctic front to the west of spitsbergen, in terms of the double-diffusive environment and the potential for densification through cabbeling. the front separates the warm, saline atlantic water in the west spitsbergen current from the cooler, fresher water on the west spitsbergen shelf. we have investigated processes at the front that can contribute to, or enhance, mixing and water mass modification in relation to heat transport to the arctic. hydrographic data were collected along a cross-shelf section in september 2005. the double-diffusive properties along the section were determined by calculating turner angles, and cabbeling was investigated with a simple linear mixing scheme. double diffusion, in the form of diffusive layering, was found to be active within the arctic front, with considerable interleaving between water masses. furthermore, mixing of water masses across the front was found to generate a potential increase in density of more than 0.03 kg m − 3 through cabbeling, which would then promote sinking and convergence. our analyses indicate that the two processes of double diffusion and cabbeling are active at the arctic front. we discuss their potential contribution to maintaining the density-compensated nature of the front, and conclude that they will promote isopycnal mixing and subsequent modification of the core water of the west spitsbergen current. keywords arctic; double diffusion; cabbeling; interleaving; mixing;turner angle. atlantic water (aw) is a key constituent of arctic oceanography. the northward flow of aw, combined with export of polar water and ice through fram strait, is the dominant heat source for the arctic ocean (schauer et al. 2004). aw is transported into the arctic through both the barents sea and fram strait, and it is the latter that is acknowledged to have the more significant influence on the temperature of the arctic basins (aagaard & greisman 1975; maslowski et al. 2004). warm, salty aw is transported through fram strait in the west spitsbergen current (wsc), a rather complex, multipath, barotropic current (manley 1995; saloranta & haugan 2001; walczowski et al. 2005). the major contribution to the northward heat transport is within the more easterly svalbard branch (manley 1995; schauer et al. 2004). this branch is confined, through topographic steering, to the upper part of the svalbard continental slope (fig. 1), and carries what has previously been termed the “warm core” of the wsc in the upper 200 m (boyd & d’asaro 1994). to the west of the wsc, the aw is separated from the cold fresh polar waters of the greenland sea by a density front (boyd & d’asaro 1994). along the shelf break there is a density front close to the surface that is associated with a layer of freshwater. beneath this layer is a front, referred to as the arctic front, manifested in temperature ( t ) and salinity ( s ) fields (saloranta & svendsen 2001). the arctic front separates the wsc from the cooler, fresher arctic-type waters on the shelf (fig. 1), which are thought to originate from the east spitsbergen current (saloranta & svendsen 2001; skogseth et al. 2005). the arctic front has no corresponding density front and in this respect it is said to be density compensated. a consistent observation of the svalbard branch of the wsc is the reported latitudinal cooling of the subsurface waters (boyd & d’asaro 1994; saloranta & haugan 2004). the rate of heat loss from the warm core is too great to be fully attributable to simple vertical heat flux through diapycnal processes. rather, it is thought that correspondence finlo r. cottier, scottish association for marine science, dunstaffnage marine laboratories, oban, argyll, pa37 1qa, uk. e-mail: fcott@sams.ac.uk. doi:10.1111/j.1751-8369.2007.00024.x f. r. cottier & e. j. venables on the double-diffusive and cabbeling environment of the arctic front, west spitsbergen polar research 26 2007 152 – 159 © 2007 the authors 153 lateral exchange with cooler neighbouring waters is the most likely mechanism. westward diffusion of heat along isopycnals into the greenland sea through an energetic eddy field was proposed by boyd & d’asaro (1994). these ideas were developed by nilsen et al. (2006), who investigated isopycnal mixing arising from the mesoscale eddy field associated with topographically trapped waves at the continental slope. they estimated lateral heat fluxes from the subsurface layers of the wsc to be o(1000) w m − 2 from moored observations and modelling simulations of isopycnal mixing through eddy diffusion in both the on-shelf (eastward) and off-shelf (westward) directions (nilsen et al. 2006). these estimates were found to be comparable to previous estimates based on the hydrographic climatology (saloranta & haugan 2004). some observed rates of northward cooling and freshening of the aw core are not consistent with pure isopycnal mixing (boyd & d’asaro 1994; saloranta & haugan 2004), and require a combination of additional mechanisms to achieve the necessary cooling/freshening ratio (saloranta & haugan 2004). further water mass modification may be achieved through exchanges across the arctic front resulting in aw leaking onto the shelf (saloranta & svendsen 2001) or extensive flushing of the shelf by aw (cottier et al. 2005). identifying the key processes by which the warm atlantic core of the wsc undergoes latitudinal cooling is essential for quantifying the delivery of heat to the arctic. it is clear that the dynamic interactions between water masses across the arctic front are important to the regional and arctic oceanography; yet, beyond its broad hydrography, the details of the characteristics of the front are still rather sparsely observed and quantified. this paper begins to address these points by describing the varying thermohaline characteristics across the front, and by offering a qualitative assessment of the potential role of double diffusion and cabbeling in frontal dynamics and subsequent water mass modifications. the phenomenon of double diffusion occurs when a water column that is gravitationally stable overall has an unstable temperature or salinity profile. this leads to either (i) salt fingering, with warm, salty water overlying cold, fresh water such that t and s both decrease with depth, or (ii) diffusive layering with cold, fresh water overlying warm, salty water with t and s increasing together with depth (turner 1973). double diffusion acts on the molecular scale, yet despite this it is capable of driving lateral interleaving across fronts by the release of potential energy through diffusive mixing of water masses with contrasting t – s characteristics (stern 1967; may & kelley 2001). the interleaving features, commonly referred to as intrusions (herbert 1999), have important implications for horizontal mixing, as they can generate unusually large eddy diffusivities, with associated lateral salt and heat fluxes (ruddick & richards 2003). significant water mass modification is possible through double diffusion (talley & yun 2001), and the interleaving process is also considered important in the maintenance of thermohaline fronts (garrett & horne 1978; simeonov & stern 2004). the process of cabbeling is a consequence of the nonlinearity of the equation of state, and refers to the densification arising through isopycnal mixing of parcels of water with the same initial density, but differing temperature and salinity. the product of the mixing, with a greater density than the parent water masses, will therefore tend to sink, and this can lead to water mass transformation (marsh 2000; talley & yun 2001; you 2003) and the maintenance of thermohaline fronts (garrett & horne 1978; horne 1978; lobb et al. 2003). this paper continues by presenting the hydrographic data collected across the arctic front, and describing the quantitative analyses for double diffusion and cabbeling. the results of these analyses are then presented and the paper concludes with a discussion of the double-diffusive environment and cabbeling in terms of the cross-front dynamics and the role in modification of aw. fig. 1 map of the svalbard archipelago and regional bathymetry. the location of the hydrographic section across the shelf west of spitsbergen is marked with a bold line, and the letters refer to the station identifiers at each end of the section. the current pathways of atlantic water and arctic-type waters are shown schematically. 154 polar research 26 2007 152 – 159 © 2007 the authors on the double-diffusive and cabbeling environment of the arctic front, west spitsbergen f. r. cottier & e. j. venables observations and methods hydrographic data were collected by the authors specifically for this study from rrs james clark ross during cruise jr127 in september 2005. a section of seven stations was occupied across the west spitsbergen shelf and over the shelf break with approximately 12 hours separating the first and the last stations. the 47-km-long section was oriented perpendicular to the isobaths, and water depths ranged from 100 m (station b) to 470 m (station i) (fig. 1). at each station, vertical profiles of temperature and conductivity were measured to within 10 m of the seabed at 24 hz using a sea-bird electronics 911plus conductivity–temperature–depth (ctd) system and a carousel water sampler. data were calibrated against bottle samples and averaged to a 1-m bin size. temperature was converted to potential temperature ( θ ) and density to potential density ( σ θ ) using standard algorithms (fofonoff & millard 1983). the hydrographic data were analysed with respect to two of the proposed frontal mixing mechanisms: double diffusion and cabbeling. double diffusion the susceptibility of the water column to double-diffusive convection can be described by the vertical density ratio, a measure of the relative contributions of t and s to the stratification. an alternative measure of the degree of density compensation is given by the turner angle ( tu ), as proposed by ruddick (1983), which provides a practical index for the nature and strength of double-diffusive activity through the water column. for each ctd profile, the susceptibility of the water column to double-diffusive convection was quantified by calculating the value of tu down each ctd profile. tu is defined as the four-quadrant arctangent of ( n 2 θ − n 2 s )/( n 2 θ + n 2 s ), where n 2 θ = ± g α d z θ and n 2 s = ± g β d z s (ruddick 1983), and where α and β are the thermal expansion and haline contraction coefficients, respectively. as defined, the water column will be diffusively unstable between − 90 ° < tu < − 45 ° , stable for | tu | < 45 ° , unstable to salt fingering for 45 ° < tu < 90 ° and gravitationally unstable for |tu| > 90 ° . to compare conditions at each station, vertical profiles of tu and the percentage of the water column susceptible to each of the four defined tu regimes was calculated from the 1-m resolution ctd data over the depth interval 1–100 m. cabbeling mixing of water masses along isopycnal surfaces will lead to cabbeling, where the density of the product water is greater than either of the two parent water masses. to estimate the density increase resulting from such mixing we followed the same procedure described by lobb et al. (2003). we selected two ctd stations with θ – s profiles representative of the two parent water masses on either side of the arctic front: arctic-type waters on the shelf and aw in the wsc. it was assumed that the waters on either side of the front mixed along isopycnals and these parent water masses formed the mixing end members. for equal values of initial σ θ the corresponding θ and s for each end member were mixed theoretically in differing proportions. the resulting increase in density was the difference between σ θ of the product water and the initial σ θ . results the distribution of θ and s from all ctd data collected along the across-shelf section is plotted in fig. 2. three distinct domains can be identified in the distribution: (i) low salinity water with s < 34.0, which is confined to the surface layers, and in late summer results from freshwater inputs primarily from local glacial melt and precipitation; (ii) cold ( θ < 4 ° c) and rather fresh water ( s < 34.9), which is arctic-type shelf water originating from the east spitsbergen current; (iii) warmer ( θ > 4 ° c) and rather saline water ( s > 34.9), which has the characteristics of aw. these domains are wholly consistent with previous descriptions of the regional hydrography (saloranta & svendsen 2001; svendsen et al. 2002; cottier et al. 2005). vertical property fields of θ , s and σ θ are presented in fig. 3. the dominant feature in the across-shelf section is fig. 2 the potential temperature ( θ ) plotted against salinity ( s ), with all the conductivity–temperature–depth (ctd) data points from the crossshelf section, gives a broad illustration of the distribution of water mass characteristics of the region. f. r. cottier & e. j. venables on the double-diffusive and cabbeling environment of the arctic front, west spitsbergen polar research 26 2007 152 – 159 © 2007 the authors 155 the steep front in both t and s , with near-vertical isotherms and isohalines, located over the shelf break between stations d and g. here the water depth increases from 120 to 300 m over a distance of 20 km. the frontal region at the shelf break is not apparent in the density section, although the isopycnals (notably σ θ = 27.8) slope offshore. in general, water on the shelf had salinities less than 34.9 and temperatures of less than 4 ° c. however, a lens of rather warmer and more saline water can be identified at 80 m at station c. the wedge of surface water, shallower than 20 m, is demarcated by the 34.0 isohaline. there is also a subsurface temperature maximum of ~4 ° c, which is possibly a remnant of earlier summer warming. off the shelf the water was warmer and more saline, and we define the boundary for aw as having a salinity of greater than 34.9 (swift & aagaard 1981). the salinity maximum ( s ≈ 35.18) in the aw at stations g, h and i was found at a depth of between 40 and 50 m. aw, indicated in the sections as the light shaded region, was also present on the shelf at station c close to the bed. maximum lateral temperature and salinity gradients, of 3 × 10 − 1 ° c km − 1 and 5 × 10 − 2 km − 1 , respectively, occurred between stations d and g at a depth of approximately 40 m. between the same stations, lateral density gradients were generally weak, with a maximum magnitude of 7 × 10 − 3 kg m − 3 km − 1 and a mean value between 30 and 100 m in depth of 1 × 10−3 kg m−3 km−1. results of the turner angle analysis of the ctd data are shown in fig. 4. a vertical section across the shelf is presented in fig. 4a, with the double-diffusive regimes of diffusive layering and salt fingering shown as shaded regions. on the shelf double-diffusion is active over the majority of the depth, predominantly through diffusive layering. in contrast, off the shelf (stations g, h and i) double diffusion is most active below 50 m, predominantly through salt fingering. at station e, located in the front, diffusive layering is active in distinct layers between 50 and 100 m. there is also active diffusive layering below the surface waters. these results are summarized in fig. 4b, which shows that in the depth interval of 1–100 m, the proportion of the water column susceptible to double-diffusive convection of either the diffusive layering or salt-fingering type amounted to 45–70%. the remaining proportion of the water column was predominantly stable. the proportion of each double-diffusive mode (diffusive layering or salt fingering) varied across the front: diffusive layering dominated the shelf area (stations b, c and d), whereas salt fingering was dominant off the shelf (stations g, h and i). the greatest percentage of double diffusivity occurred within the arctic front at station e, where diffusive layering was dominant. a density increase as a result of cabbeling was found to occur along isopycnals between σθ = 27.4 and 27.8 (fig. 5). the maximum density increase exceeded 0.03 kg m−3 for mixing of waters with σθ = 27.65, where the largest differences in θ (∆θ ~ 5°c) and s (∆s ~ 0.6) occurred. the characteristics of interleaving are inversions of temperature and/or salinity, most easily seen in θ–s data (walsh & carmack 2003). in fig. 5 interleaving was identified at station e, lying between the two end member profiles (d and g). five intrusions were identified fig. 3 vertical sections crossing the shelf of (a) potential temperature, (b) salinity and (c) potential density. letters and vertical dotted lines identify the stations and the light-grey shaded area in each section marks the extent of atlantic water. bold isohalines in (b) demarcate atlantic water and fresh surface water. the bold 27.65 isopycnal in (c) is referred to in the text. 156 polar research 26 2007 152 – 159 © 2007 the authors on the double-diffusive and cabbeling environment of the arctic front, west spitsbergen f. r. cottier & e. j. venables between 40 and 80 m in depth that have a typical vertical length scale of 5 m, and the distance of 14.4 km between stations d and g constrains the magnitude of their horizontal length scale. discussion in this paper we have described the density-compensated arctic front located at the svalbard continental slope, and presented the first assessment of its double-diffusive nature and potential water mass modification through isopycnal processes. the hydrography of the front, as observed in september 2005, is found to be consistent with previous descriptions (boyd & d’asaro 1994; saloranta & svendsen 2001; cottier et al. 2005). however, the existence of this t–s front is not always clear (haugan 1999), and at some locations along the west spitsbergen shelf it is absent under certain shelf-exchange conditions (cottier et al. 2005). the hydrographic structure on the shelf undoubtedly has a seasonal nature, particularly the depth of the surface layer, which is formed primarily through glacial melt and precipitation (svendsen et al. 2002), and the occurrence of a subsurface temperature maximum is likely to be related to summer warming. however, in general the shelf hydrography remains stratified, even during winter (boyd & d’asaro 1994; cottier et al. 2005). it is important to correctly interpret the lens of rather saline water on the shelf at a depth of 80 m at station c. unlike many other arctic shelves, the west spitsbergen shelf is dominated by advected sea ice rather than locally formed sea ice (boyd & d’asaro 1994), and consequently such saline water is unlikely to be the result of brine released during fig. 4 (a) vertical section across the shelf showing the distribution of turner angles derived from the conductivity–temperature–depth (ctd) data. the block shading illustrate the unstable (us), diffusive layering (dl), salt fingering (sf) and stable (st) regimes. (b) vertical section showing the proportion of double-diffusive convection type (�, salt fingering; �, diffusive layering) occurring at each station across the shelf. depth is indicated on the left-hand y-axis and the percentage of double-diffusivity type is marked on the right-hand y-axis. the extent of atlantic water is indicated by the light-grey shaded area and the horizontal dashed line is the 100-m depth limit for the calculation of the proportions. (a) (b) fig. 5 the potential temperature (θ) plotted against salinity (s) illustrates the increase in density through linear mixing of water mass end members and cabbeling. the shelf water end member is station d and the atlantic water end member is station g; indicated by bold black lines. station e, within the arctic front, is indicated by the bold grey line. the increase in potential density through linear mixing of varying proportions of the end members is indicated by the dashed black contours of equal density change. contours are drawn at 0.005 kg m−3 intervals. f. r. cottier & e. j. venables on the double-diffusive and cabbeling environment of the arctic front, west spitsbergen polar research 26 2007 152 – 159 © 2007 the authors 157 the previous winter. furthermore, the lens has a temperature of >3°c, which is thus consistent with cross-front leakage and the layering of aw with shelf waters as described by saloranta & svendsen (2001). although saloranta & svendsen (2001) associated leakage of aw with the presence of submarine valleys, or channels, cutting across the shelf, our observations show that it also occurs in a location without such topographic features. either this leakage can occur along the length of the shelf or these pockets of aw are readily advected. complete summertime flushing of the shelf area by aw, as reported by cottier et al. (2005), has not occurred at this location. this raises questions of the generality of the flushing phenomenon in both time and space; is it associated solely with across-shelf channels or does it occur on an interannual basis only? one widely reported aspect of the shelf hydrography is the presence of a surface density front associated with a wedge of fresh water (boyd & d’asaro 1994; saloranta & svendsen 2001). our results do not reveal this front, as the surface layer depth is rather uniform and the westward extent of surface water is beyond our section. the distinct surface layer, demarcated by the 34.0 isohaline in fig. 3b, and a rather strong pycnocline at about 20 m in depth, will tend to minimize heat loss through diapycnal processes. consequently, it is valid for us to focus our discussions on what has been termed the subsurface layer with respect to cooling of the warm core of the wsc (boyd & d’asaro 1994; saloranta & haugan 2004; nilsen et al. 2006). within the front (station e) there is evidence in the subsurface layer of interleaving between the arctic waters on the shelf and the aw (fig. 5). this observation is reinforced by the active diffusive layering at station e in the depth range 50–100 m (fig. 4a). there are a number of important consequences of the interleaving process. first, it sets up a lateral mixing of heat and salt (ruddick & richards 2003), and the magnitude of associated lateral eddy diffusivities are reported to range from a few to several thousand m2 s−1 (ruddick & gargett 2003). second, it brings contrasting water masses together over a broad interface, which will enhance water mass transformation (talley & yun 2001). third, it permits diapycnal mixing through double diffusion at the interface of the interleaving layers (schmitt et al. 2005). the interleaving situation is illustrated schematically in fig. 6. from the limited dataset it is not realistic to make quantitative estimates for each contributory process, but they are clearly active and likely to be relevant to the modification of the inshore branch of the wsc. whereas this is the first description of such interleaving features in the front to the west of spitsbergen, ctd data presented by haugan (1999: fig. 4) provide additional examples of interleaving in waters of 600 m in depth. interleaving will promote water mass modification in the warm core through double diffusion. the change in the form of double diffusion between the shelf and the shelf slope is related to the temperature and salinity stability of the water column. on the shelf, at station d for example, the water is predominantly stable with respect to salinity but is unstable with respect to temperature, with warmer water lying beneath cooler waters (fig. 5). this situation gives rise to the diffusive layering form of double diffusion (fig. 4a). the active diffusive layering across the front is likely to support the formation of the regular interleaving structures identified at station e in fig. 5. in contrast, at station g, there is a gradual decrease in salinity below 50 m, with the temperature profile having a stable form. this leads to salt fingering. cabbeling is a product of isopycnal mixing, and at the front this is likely to be further enhanced by the process of interleaving that was identified in fig. 5, and was discussed earlier. our analysis of the data has shown a potential increase in density through cabbeling of greater than 0.03 kg m−3 when mixing water across the front. this maximum is located along σθ = 27.65, which has a very small lateral gradient (fig. 3c) requiring minimal work to achieve isopycnal mixing. clearly this theoretical approach draws on a number of assumptions. first, that such isopycnal mixing actually occurs. significantly, at station e there is water with the required θ–s properties that are not found in the parent water masses and can only result from such isopycnal mixing. second, the estimate of densification is reliant on identifying appropriate parent water masses as the end members. fig. 2 shows that the θ–s signature for the two parent water masses is distinct and well defined on either fig. 6 diagram of the double diffusive interleaving that occurs at the arctic front between atlantic water and the arctic-type shelf waters. the interleaving permits effective isopycnal mixing between contrasting water masses, leading to increased density of the product water, sinking and convergence. 158 polar research 26 2007 152 – 159 © 2007 the authors on the double-diffusive and cabbeling environment of the arctic front, west spitsbergen f. r. cottier & e. j. venables side of the front. finally, our estimates are based on one section only. however, in late summer, we would expect to see the smallest contrast in θ–s properties between the parent water masses. therefore, we consider our estimate of the magnitude of densification to be valid along much of the arctic front west of spitsbergen. the dynamical effect of densification is increased vertical velocity leading to convergence of waters at the front (garrett & horne 1978; ruddick & gargett 2003), and this is illustrated in fig. 6. therefore, the hydrographic contrast between the aw and the arctic waters, the generation of interleaving layers and the process of cabbeling through isopycnal mixing, may act to maintain the t–s front. it is unlikely that the cabbeling process will generate a new, distinct water mass, as has been reported elsewhere (talley & yun 2001). additionally, the absolute vertical heat and salt fluxes associated with the doublediffusion processes are most likely to be secondary to those produced by externally forced mixing. however, we conclude that the double-diffusive processes support interleaving of water masses leading to convergence at the front, and thereby permit the required isopycnal mixing for cooling of the warm core (saloranta & haugan 2004; nilsen et al. 2006). although these mesoscale effects may make the greater contribution to lateral heat flux, in this paper we offer a mechanism that supports such isopycnal processes. despite the acknowledged importance of the arctic front west of spitsbergen in modifying the communication of the wsc with cooler shelf waters, there are rather few descriptions of it. here we have illustrated the density-compensated nature of the front and identified the regimes of double-diffusive activity. we have also shown from the ctd data that thermohaline interleaving is a characteristic of the front. finally, we presented evidence for active cabbeling, which will lead to convergence. these processes will tend to promote water mass modification and provide a mechanism for the maintenance of the t–s contrast at the front. future work should focus on the spatial and temporal extent of the interleaving characteristics and quantify these processes in supporting isopycnal mixing across the front. acknowledgements the authors would like to thank the master, crew and pso of rrs james clark ross for ctd operations during jr127. we appreciate the assistance of colin griffiths with data processing and mark inall for useful discussion and input to this manuscript. valuable comments from two anonymous referees greatly improved the quality of the manuscript. the majority of the numerical analyses were completed by ejv as part of a masters dissertation at the university of southampton, supervised by simon boxall. this work was funded by the natural environment research council and is a contribution to the sams northern seas programme. references aagaard k. & greisman p. 1975. toward new mass and heat budgets for the arctic ocean. journal of geophysical research 80, 3821–3827. boyd t.j. & d’asaro e.a. 1994. cooling of the west spitsbergen current: wintertime observations west of svalbard. journal of geophysical research 99, 22597–22618. cottier f.r., tverberg v., inall m.e., svendsen h., nilsen f. & griffiths c. 2005. water mass modification in an arctic fjord through cross-shelf exchange: the seasonal hydrography of kongsfjorden, svalbard. journal of geophysical research 110, e12005, doi:10.1029/2004jc002757. fofonoff p. & millard r.c. 1983. algorithms for computation of fundamental properties of seawater. unesco technical papers in marine science 44, 53. garrett c. & horne e. 1978. frontal circulation due to cabbeling and double diffusion. journal of geophysical research 83, 4651–4656. haugan p.m. 1999. structure and heat content of the west spitsbergen current. polar research 18, 183–188. herbert d. 1999. intrusions: what drives them? journal of physical oceanography 29, 1382–1391. horne e. 1978. interleaving in the subsurface front in the slope water off nova scotia. journal of geophysical research 83, 3659–3671. lobb j., weaver a.j., carmack e.c. & ingram r.g. 2003. structure and mixing across an arctic/atlantic front in northern baffin bay. geophysical research letters 30, no.16, 1833, doi:10.1029/2003gl017755. manley t.o. 1995. branching of the atlantic water within the greenland–spitsbergen passage: an estimate of recirculation. journal of geophysical research 100, 20627–20634. marsh r. 2000. cabbeling due to isopycnal mixing in isopycnic coordinate models. journal of physical oceanography 30, 1757– 1775. maslowski w., marble d., walczowski w., schauer u., clement j.l. & semtner a.j. 2004. on climatological mass, heat and salt transports through the barents sea and fram strait from a pan-arctic coupled ice–ocean model simulation. journal of geophysical research 109, co3032, doi:10.1029/ 2001jc001039. may b.d. & kelley d.e. 2001. growth and steady state stages of thermohaline intrusions in the arctic ocean. journal of geophysical research 106, 16783–16794. nilsen f., gjevik b. & schauer u. 2006. cooling of the west spitsbergen current: isopycnal diffusion by topographic vorticity waves. journal of geophysical research 111, co8012, doi:10.1029/2005jc002991. ruddick b. 1983. a practical indicator of the stability of the water column to double-diffusive activity. deep-sea research 30, 1105–1107. f. r. cottier & e. j. venables on the double-diffusive and cabbeling environment of the arctic front, west spitsbergen polar research 26 2007 152 – 159 © 2007 the authors 159 ruddick b. & gargett a.e. 2003. oceanic double-infusion: introduction. progress in oceanography 56, 381–393. ruddick b. & richards k. 2003. oceanic thermohaline intrusions: observations. progress in oceanography 56, 499–527. saloranta t.m. & haugan p.m. 2001. interannual variability in the hydrography of atlantic water northwest of svalbard. journal of geophysical research 106, 13931–13943. saloranta t.m. & haugan p.m. 2004. northward cooling and freshening of the warm core of the west spitsbergen current. polar research 23, 79–88. saloranta t.m. & svendsen h. 2001. across the arctic front west of spitsbergen: high-resolution ctd sections from 1998–2000. polar research 20, 177–184. schauer u., fahrbach e., østerhus s. & rohardt g. 2004. arctic warming through the fram strait: oceanic heat transport from 3 years of measurements. journal of geophysical research 109, c06026. schmitt r.w., ledwell j.r., montgomery e.t., polzin k.l. & toole j.m. 2005. enhanced diapycnal mixing by salt fingers in the thermocline of the tropical atlantic. science 308, 685– 688. simeonov j. & stern m. 2004. double-diffusive intrusions on a finite-width thermohaline front. journal of physical oceanography 34, 1723–1740. skogseth r., haugan p.m. & jakobsson m. 2005. watermass transformations in storfjorden. continental shelf research 25, 667–695. stern m. 1967. lateral mixing of water masses. deep-sea research 14, 747–753. svendsen h., beszczynska-møller a., hagen j.o., lefauconnier b., tverberg v., gerland s., ørbæk j.b., bischof k., papucci c., zajaczkowski m., azzolini r., bruland o., wiencke c., winther j.-g. & dallmann w. 2002. the physical environment of kongsfjorden–krossfjorden, an arctic fjord system in svalbard. polar research 21, 133–166. swift j.h. & aagaard k. 1981. seasonal transitions and water mass formation in the iceland and greenland sea. deep-sea research 28, 1107–1129. talley l.d. & yun j.-y. 2001. the role of cabbeling and double diffusion in setting the density of the north pacific intermediate water salinity minimum. journal of physical oceanography 31, 1538–1549. turner j.s. 1973. buoyancy effects in fluids. cambridge: cambridge university press. walczowski w., piechura j., osinski r. & wieczorek p. 2005. the west spitsbergen current volume and heat transport from synoptic observations in summer. deep-sea research i 52, 1374–1391. walsh d. & carmack e.c. 2003. the nested structure of arctic thermohaline intrusions. ocean modelling 5, 267–289. you y. 2003. implications of cabbeling on the formation and transformation mechanism of north pacific intermediate water. journal of geophysical research 108, no. c5, 3134, doi:10.1029/2001jc001285. problems of quaternary geology and palaeoecology of north european seas gennadyi matishov matishov, g . 1987: problems of quaternary geology and palaeoecology of north european seas. polar research 5 n s . , 291-292. gennadyi matishov, institute of marine biology, academy of sciences ussr, 18631 dalnie zelentsky murmansk region, ussr. the quaternary geology in the recent 25 years has been char acterized by an intense accumulation of data and by the devel opment of a number of hypotheses on the history and evolution of the barents sea (boulton 1979; elverhdi & solheim 1983; vorren & kristoffersen 1986). the main feature of the climate transformation in the cenozoic era was the great continental glaciation and the oceanic penglacial area (matishov 1984, 1987). characteristic forms of relief eroded by continental ice are fjords, marginal and transversal trenches, and marginal glacial formations of the sea floor. at a distance of 100 to 200 km from the coast, at depths of 50 to 400111, several belts of pleisto cene glacial deposits of a total thickness of up to 200m are found. during glacial periods, the environment of glacial shelves has been determined by continental ice which has covered vast areas of the ocean floor. vertical glacio-eustatic movements, reaching up to several hundred metres, absence of runoff of northern rivers, and changc of the general circulation of the atmosphere and of the ocean have radically changed the course of events in the biosphere. in the open sea, pelagic organisms (e.g. plank ton) have been affected more than others. at the stage of the maximum development of glaciations, ice flowed out to the shelf edge of northern europe, greenland, canada and antarctica. asynchronous formations of vast glacier covers on the sea floor are not ruled out. in such situations glaciers have affected the life both of planktonic and of benthic communities of the shelf. regarding roughly the ‘great’ glaciation periods of the barents sea, we notice that the typically glacial barents sea shelf has more than once been the scene of activity for glaciers which have flowed down from the surrounding continents (matishov 1984). i n the southern part of the sea, more than 150 m from the coast/shore, debris of scandinavian and kola crystallinc rocks occur widely in recent deposits. during the maximum of the glaciation (18,000 to 20,000 years ago) the greater part of the shelf was probably covered with continental ice of a thickness of up to 300 and even 700m. neighbouring glacier flows could unite/merge with their floating ice shelves over large depressions of the bottom of the central part of the barents sea. areas with drifting icebergs and with pack ice are probable here (fig. 1). during the glaciation the retreat was accompanied by a series of oscillations. in the younger dryas (11,000 to 10,000 years ago) the con tinental ice did not extend outside the fjord coast. local glacier domes apparently developed on bj0rnoya. hopen and the cen tral bank. glaciers on the spitsbergen bank moved mainly in southern and western directions along pre-quaternary valleys. such an intense asymmetry of the bjdrnoya-hopen glacial cover has apparently been brought about by the comparatively dry and severe climate which dominated in the central areas of the barents sea. an analysis of the traces of glaciation on hopen has shown that striated surfaces are here connected with the activity of pack ice or of floating ice (hoppe 1981). i n this connection hoppe (1969) has his doubts in his previous con clusions as to the possible spread to spitsbergen from the barents sea shelf of the hypothetical glacier cover. constantly more geological data have appeared, testifying to the metachronolcgy of development of the quaternary glaci ation in the arctic and in middle latitudes. on the whole, the weichselian glacial movements in svalbard, in northern poland and on the russian plain coincide well in time. however. the early weichselian glaciation (45,000 to 35.000 years ago) manifested itself most intensely in the arctic. the scale of the subsequent movements decreased gradually, whereas in northeastern europe a reversed picture is observed where the largest dimensions have been reached by the late weichselian glaciation. in the late weichsclian, svalbard was covered by a relatively thin glacier with its centre in the eastern part of the archipelago. i t is quite possible that during the latest glaciation (21,000 to 17.000 years ago) the continental ice, flowing down from novaja zemlja, the northern urals and the kola peninsula to the southeast of the barents sea shelf, including the pecora sea, rushed asynchronously on to the sea floor. under such circumstances the large goose bank, the northern kanin bank and other banks could have developed under terrestrial peri glacial conditions. referring to palaeochemical problems of the ocean, it should he noted that in sea water, which has a mean salinity of 34.4%. the content of chlorine reaches 19 g per litre. for that reason, as a geochemical indicator of fluctuations/variations of marine salinity, the chlorine content of pore water is used. ions of chlorine (ci) give the most reliable material for determining the directions of the changes of salinity of the near-bottom waters during sedimentation. an analysis of the chemical composition of pore water in 2-3 m long cores of barents sea bottom deposits has shown that pore water with respect to saline composition corresponds on the whole to sea water (pavlova 1976). besides, in a number of cases viscous, clayey deposits at the bottom of shelf trenches are characterized by a low content of chlorine (16.5 t o 18.9g per litre). this difference of one t o two grams per litre testifies to the existence in the pre-holocene history of the barents sea basin of phases with less saline sea water. 292 g. matishov fig. i . contincntal glaciation on the barents sea shclf in the late pleistocene ( 2 0 . w 1 8 . 0 0 years ago). probahlc scheme: i ) maximum extent of the continental ice 2o.ofx~-18.ooo years ago. 2 ) ice shelf. floating ice. 3) marine pcriglacial with drifting icebergs and pack ice. 4 ) periglacial (terrestrial) zone of the shelf. 5 ) f l o w lines. 6) isobath 200m. references boulton. g . s. 1974 glacial history of the spitsbergen archi pelago and thc problem of a barcnts shelf ice sheet. boreas 8. 31-57. elverhei, a . & solherm. a . 1983: the barenls sea ice shcct a sedimcntological discussion. polar research i n . s . , 23-42. hoppe. g . 1969: studies of the glacial history of hopen (hopcn island). svalbard. geogr a n n 5 1 a ( 4 ) . 185-192. hoppe. g . 1981: glacial tracer on the island of hopen. svalbard: a correction. geogr. ann. 63afi-2). 6 7 4 8 . matishov. g . g . 1984: dno okeana u lyednikooi period (the floor of the ocean during the ice age). nauka (published for the ussr academy of sciences). leningrad. 180 pp. (in russian). matishov. g. g. 1487: miroooi okean i oledenenie zemli (the world ocean and glaciation of the earth). mysl, moscow. 270 pp. ( i n russian). pavlova, l. g . 1976: geochimia ilovih vod v ekologii morja (geochemistry of muddy waters in the sea ecology). pp. 62 84 in paleogeografia i paleoekologia barentseoa i belogo morej u ch;'uertichni period (palaeoecology and palaeo geography of t i e barents and the white seas in the quat ernary period). apatiti (in russian). vorren. t. & kristoffersen, y. 1986: late quaternary glaci ation in the south-western barents sea. boreas 15, 51-59. mikhalevsky.indd 185mikhalevsky & gavrilov 2001: polar research 20(1), 185–192 acoustic thermometry in the arctic ocean peter n. mikhalevsky & alexander n. gavrilov large increases in the temperature of the atlantic layer in the arctic ocean have been observed since the early to mid-1990s and have continued through to the present. these changes were detected in 1994 and in 1999 with acoustic “sections” using acoustic thermometry. both icebreaker and submarine ctd sections have confirmed these observations. calculations of the travel time of acoustic mode 2 for the submarine ctd sections show a linear correlation with the mean temperature of the atlantic layer of the section. a cabled-to-shore undersea mooring system of arctic ocean observatories is needed to provide real-time year-round observations using conventional as well as acoustic remote sensing techniques. p. n. mikhalevsky, science applications international corporation, 1710 saic dr., mclean, va 22102, usa; a. n. gavrilov, p. p. shirshov institute of oceanology, russian academy of science, 36 nakhimovskii prospekt, moscow 117851, russia. the arctic ocean plays a key role in the global thermohaline circulation of the world’s oceans and exercises considerable influence on global climate, especially in the northern hemisphere. climate models predict that the arctic regions should be the first to experience the influence of global warming (manabe et al. 1992). this influence is possibly already happening at present in the form of considerable warming of water in certain regions of the arctic ocean. since the early 1990s inflow of warmer water from the northern atlantic into the arctic basin has resulted in a temperature increase in the atlantic layer from approximately 50 m to 1000 m in the regions along the atlantic water circulation (carmack et al. 1995). the arctic ocean is the least accessible for oceanographic measurements with the use of traditional “contact” methods from research vessels due to severe climatic conditions and the yearround sea ice cover. arctic researchers therefore need remote sensing methods to make year-round observations. however, methods of remote observation of the ocean such as satellite altimetry of the ocean surface and measurements of sea surface temperature are not possible in the arctic because of the perennial ice cover. autonomous vehicles and sub-surface drifters are still under development. low frequency acoustics offers an effective technique for remote sensing of the water temperature in the arctic ocean. with receiving hydrophone arrays that are cabled to shore, ocean temperature measurements can be provided in real time. acoustic thermometry is a proven technical approach to the problem of remote observation of large-scale variation of temperature in the ocean, including climatic changes (dushaw et al. 2001). the method of acoustic thermometry of the ocean suggested by munk & forbes (1989) is based upon the almost linear dependence of the sound speed in water on temperature. measuring the travel time of acoustic propagation between a fixed source and a receiver in the ocean, it is possible to determine changes in the average temperature of water along the propagation path. sound can propagate in the ocean over thousands of kilometres, which makes it possible to create integral acoustic thermometers overlapping in individual large basins, and with tomographic inversion these integral measurements can provide spatial resolution directly proportional to the number and density of intersecting acoustic paths in each of the basins. 186 acoustic thermometry in the arctic ocean acoustic propagation in the arctic ocean the efficiency of acoustic thermometry in the arctic ocean follows from the unique characteristics of sound propagation in the arctic underwater acoustic channel. the acoustic energy of low frequency signals propagates in stable welldefined waveguide modes in the vertically stratified water mass layers of the arctic ocean. when propagating, the lowest modes (mode 1 at 20 hz, for example) occupy mainly the upper mixed layer of cold and less saline arctic waters. the maximum energy of the higher modes (modes 2 and 3 at 20 hz) propagates in the intermediate layer of warmer and more saline waters of atlantic origin (hence the name atlantic layer) that circulate over the entire arctic basin (mikhalevsky et al. 1995). there is therefore an opportunity for remote observation of the temperature variation in the typical water mass layers of the arctic ocean by filtering the signals arriving in different acoustic modes. the modes travel at different group velocities corresponding to the different sound speeds in the arctic water layers so simple time filtering can be done for those paths whose ranges are long enough for the modes to separate, typically greater than several hundred kilometres. for shorter ranges the modes can be filtered spatially with a vertical array. figure 1 shows the relationship between the average temperature of the atlantic layer, defined as a layer bounded by the zero degree isotherms, and the group velocity of modes 2 and 3, i.e. the velocity of propagation of an acoustic pulse signal. 754 ctd profiles measured in the arctic since the 1950s were used to calculate this correlation. the plot clearly shows that the relationship between the acoustic modal group velocity and the atlantic layer temperature is almost linear and the correlation coefficient calculated for the best linear fit is close to unity. since the actual acoustic thermometry measurement is a travel time along a propagation path the correlation of the travel time with the average temperature in the atlantic layer on a specific path effectively depends upon a much smaller subset of the profiles shown in fig. 1 (which represents the entire arctic) and should be calculated for the specific path as done below. the correlations are even higher if one considers profiles from only the western arctic (makarov and canada basins) and the eastern arctic (nansen and amundsen basins), which correspond to the points less than ~0.7 °c and greater than ~0.7 °c, respectively, in fig. 1. in april 1994 acoustic transmissions at 20 hz were made from the ice camp turpan north of svalbard across the entire arctic ocean to receive arrays located at ice camp narwhal in the lincoln sea and ice camp simi in the beaufort sea. this fig. 1. the mean temperature between the zero degree isotherms of 754 ctd profiles from the arctic ocean plotted against the modal group velocity for that profile for mode 2 (stars) and mode 3 (circles). ccorr is the correlation coefficient calculated for the best linear fit. 187mikhalevsky & gavrilov 2001: polar research 20(1), 185–192 was the transarctic acoustic propagation (tap) experiment (mikhalevsky et al. 1999). the travel time of mode 2 measured in the tap experiment was shorter by approximately 2 seconds (2.3 ± 1.2 sec) relative to that modelled for the arctic ocean climatology data along the propagation path, which indicated a warming of the atlantic layer by almost 0.4 °c (± 0.2 °c) of the range averaged maximum temperature in depth. the maximum in depth of the range average of the temperature difference in the atlantic layer computed from the us navy generalized digital environmental model (gdem) (teague et al. 1990; teague et al. 1987) and us–russian environmental working group (ewg) arctic database (ewg 1997) with the 1995 submarine ctd transect showed 0.3 °c and 0.5 °c increases, respectively. error statistics provided with the ewg database indicate an error of ± 0.2 °c for an average over the three major arctic basins spanned by the transect. the april 1994 tap acoustic section was the first basin scale measurement indicating a net warming over such a large scale in the atlantic layer of the arctic ocean. the arctic ocean section of the us ice-breaker polar sea and the canadian ice-breaker louis s. st. laurent conducted in august 1994, as well as subsequent basin transects performed by the us navy scientific ice expeditions (scicex; lamont-doherty earth observatory 2001), confirmed the results of the acoustic measurements. the warming of the atlantic layer in the 1990s is an established fact. what has not been established is whether this change is a manifestation of a secular global climate change trend with an anthropogenic fingerprint, or a “natural” oscillation (proshutinsky & johnson 1997; grotefendt et al. 1998). the need for a real-time long-term observational system is clearly evident to understand these phenomena in the arctic ocean. arctic climate observations using underwater sound in october 1998, as part of the joint us–russian arctic climate observations using underwater sound (acous) project, the first acoustic sourcewas deployed by the russian team in the franz victoria strait. at the same time, a us–canadian fig. 2. a notional monitoring grid for the arctic ocean. the stars represent the three autonomous acoustic sources. the filled and open circles indicate the cabled receive arrays and arctic ocean observatories. the open circle in the lincoln sea represents an existing sea–shore interface. the open circle in the beaufort sea represents a sea–shore interface which does not yet exist. the open circle in the chukchi sea shows the aplis ice camp location. the short-dashed grey line from the acous source to the lincoln sea is the acoustic path along which acoustic thermometry transmissions were made from october 1998 to december 1999. the long-dashed grey line is the acoustic path from the acous source to the aplis ice camp in the chukchi sea along which acoustic thermometry measurements were made in april 1999. 188 acoustic thermometry in the arctic ocean team was in the lincoln sea deploying an autonomous receive array. in april 2001 this receive array was recovered. this vertical array was moored from the bottom in about 550 m of water. the array consisted of 8 hydrophones spaced at 70 m intervals, starting at 12 m from the bottom. the array also had 5 self-recording micro-ctds that record temperature and salinity every 10 minutes. there were two self-recording transceivers on the array that interrogated three bottommounted transponders to measure the shape of the array. the source–receiver pair creates a propagation path that crosses the arctic basin just north of the fram strait (fig. 2). preliminary analysis of the data shows that the source operated successfully until 8 december 1999, when it ceased transmissions due most likely to depletion of the batteries. the source was moored from the bottom at a depth of 60 m below the sea surface and transmitted a maximal length sequence (mls) tomographic signal at 20.5 hz every four days at 00:00 gmt. the total signal duration is about 20 minutes. the signal level is 250w (195 db re 1 µpa) of acoustic power. the transmission time was controlled by a quartz oscillator that was corrected every four days by a rubidium clock, based on a technique that has been in use on fig. 3. temperature sections from scicex 1995, 1998 and 1999 across the arctic basin with the coincident bathymetry. the significant warming in the atlantic layer is evident as topographically guided extensions of the atlantic water circulation. an average in range of these sections plotted as a function of depth shows a 0.4 °c maximum increase between 1995 and 1998-99 at approximately 250 m. 189mikhalevsky & gavrilov 2001: polar research 20(1), 185–192 autonomous tomographic moorings for some time (worcester et al. 1985). the clock was synchronized to gps just before deployment, and predeployment tests indicated better than 0.6 msec absolute timing accuracy. the acoustic data set from this path should reveal any changes in the net heat influx into the arctic ocean over the 14 month period between october 1998 and december 1999. these acoustic data will be compared with new models under development at the university of alaska fairbanks, which are attempting to nowcast and forecast the regime shifts and current state of the arctic ocean (johnson et al. 1999). in april 1999 the ice camp aplis was established in the chukchi sea to support the scicex-1999 expedition (fig. 2). two recordings of the regular acous transmissions were made at the ice camp on 9 and 13 april. the acoustic path from the acous source to aplis is close to the scicex transects conducted in 1995, 1998 and 1999. figure 3 shows the temperature field along the path in 1995, 1998 and 1999 constructed from expendable ctds launched from the submarine at approximately 40 km intervals. the expendable ctd probes have an accuracy of ± 0.035 °c in temperature and 4.6 m or 2 % of depth, whichever is greater, and make measurements between 25 m and 1000 m in depth. the areas of warmer atlantic water located to the left of the major undersea ridges in the figure coincide with the main streams of the atlantic layer circulation in the arctic basin. the plot clearly shows the considerable warming in the atlantic layer in 1998 and 1999 relative to 1995. the maximum in depth of the range averaged temperature difference between 1995 and 1999 showed a 0.4 °c increase in temperature, and from 1998 to 1999 a 0.05 °c increase. however, due to the change in depth of the warm cores of the atlantic layer from year to year (fig. 3), it is estimated that the error of the range averaged maximum is probably close to ± 0.05 °c. a more robust and statistically stable measurement, which is not going to be sensitive to depth changes of the warm cores within the atlantic layer, is the range and depth averaged temperature for the section between the 0.0 °c isotherms that define the atlantic layer. given that there are approximately 4000 independent data points from the expendable ctds in the atlantic layer of each section, the error of the average temperature is ± 0.6 m°c. the atlantic layer in the scicex-99 transect was warmer by 0.01 ± 0.0006 °c on average over the entire section (range and depth) than that in 1998. figure 4a shows the variation of the mean atlantic water temperature along the section and the section average values. the calculated group velocity of mode 2 (fig. 4b) strongly correlates with the horizontal variation of the mean temperature. the travel time of mode 2 modelled for the t/s fields fig. 4. (a) average temperatures between the zero degree isotherms plotted as a function of range for scicex 1995, 1998 and 1999. the numbers in the upper right corner are the averages over the range of the plotted curves and therefore represent the twodimensional average temperature of each section. (b) the mode 2 group velocity plotted as a function of range for scicex 1995, 1998 and 1999. (b) the total computed travel time for mode 2 is shown in the lower left corner. (a) (b) 190 acoustic thermometry in the arctic ocean in 1995, 1998 and 1999 depends on the total section average of the atlantic layer temperature almost linearly (fig. 5). the travel time of mode 2 measured at aplis in april 1999 was 2.7 ± 1.3 seconds shorter compared to the april 1994 tap measurement (corrected for the different path lengths). this implies a 0.5 ± 0.25 °c increase in the range averaged maximum temperature in depth over 5 years compared with the submarine measured increase of 0.4 ± 0.05 °c from 1995 to 1999 over 4 years discussed above. the measured travel time of mode 2 along the aplis path was 1.2 ± 0.5 seconds shorter than modelled using the scicex-99 ctd data. since scicex could not sample the first 300 km section of the acoustic propagation path (due to operational restrictions), some recent oceanographic measurements from this region in 1993 were used for the acoustic modelling for the first 300 km. this 300 km section is the warmest part of the acoustic path, because it stretches from the franz victoria strait toward the north pole and samples the extension of the west spitsbergen current. such a compilation of older oceanographic data with the newer scicex data on this section could explain the disagreement between the experimental and modelling results for 1999, with the modelling results biased slower, as was observed. nevertheless, both the modelling and the experimental acoustic and submarine ctd data demonstrate considerable warming in the atlantic layer along this section in 1999 relative to 1994 and 1995. the errors associated with the absolute travel times reported above for mode 2 from the tap and aplis experiments were dominated by the fact that in tap the source transmission was initiated by manual synchronization with the rubidium clock (the receive systems were electronically synchronized) and in aplis the receive system had to be manually synchronized with a gps (a consequence of experiment field problems). this resulted in absolute travel time measurement errors of ± 1.2 seconds in tap and ± 0.5 seconds in aplis. with electronic synchronization the travel time errors and the accuracy are reduced to the precision of the mls measurement, which depends upon the bandwidth of the mls waveform (1.5 hz for tap and 2 hz for aplis) and the received signal-to-noise ratio (snr). for tap and aplis, the longest trans-arctic path to the beaufort and chukchi seas, respectively, had a received post-processing snr of ~18 db and ~21 db for mode 2, respectively. for the shorter path to the lincoln sea the snr was even higher. as shown in mikhalevsky et al. 1999 (eq. 1), this yields a time measurement precision of ~30 msec and ~22 msec, respectively, by picking the peak of the pulse compressed waveform in time. travel time changes using a modal phase measurement method (also shown in mikhalevsky et al. 1999) further reduced these errors to ~0.7 msec and ~0.5 msec, respectively. using the linear trend shown in fig. 5 of 0.044 °c sec-1, a 22 msec travel time error would correspond to 0.9 m°c error in the section average temperature on this path (and 0.02 m°c error using the phase method). these small errors are also a consequence of the nearly perfect linear relationship of the section average temperature and travel time for the three data points shown in fig. 5. if this linear relationship does not hold up when new data are available then these errors must be increased depending upon the goodness of the linear fit. finally, the travel time accuracies assume that the modal propagation is adiabatic. if significant mode coupling occurs along the propagation path then associating a measured travel time with a particular mode is problematic. even a small amount of mode coupling can increase the errors associated with the waveform peak picking measurement discussed above. analysis of the bathymetrically caused mode coupling on the lincoln sea path during the tap experiment (pawlowicz et al. 1996; gavrilov & mikhalevsky 2001) has shown that the phase method is much more robust to errors caused by mode coupling than the waveform peak picking method. the analysis also showed that travel time errors using the phase method would be less than 10 msec. the measured scicex ctd and acoustic data, and acoustic modelling using the scicex ctd data, have shown that the warming in the atlantic layer of the arctic ocean have decreased the trans-arctic travel time of mode 2 by ~0.4 sec/yr. clearly, these changes, and changes even two orders of magnitude less than this, on an annual basis will be easily detectable using acoustic thermometry. a future monitoring network for the arctic ocean a notional monitoring network for the arctic ocean is shown in fig. 2. this grid provides an integrated arctic ocean observing system 191mikhalevsky & gavrilov 2001: polar research 20(1), 185–192 exploiting the capabilities of acoustic remote sensing and direct measurements of important physical ocean properties using cabled moorings and autonomous acoustic sources. the notional network consists of 6 ocean observatories with acoustic receive arrays and 3 autonomous acoustic sources. the scheme shows that an 18 acoustic path system will sample every major arctic sub-basin and intersect every major branch of the atlantic and pacific water circulation. the acoustic signal takes 30 min to propagate along the longest path from franz josef land to the beaufort sea array. the acous source currently operating in the arctic sends a 20 min signal every four days. thus, the notional network shown here could provide a snapshot of the entire arctic ocean in less than 1 hour every 4 days, and could operate for years with all of the data being provided to researchers in real-time. the data would provide information on temperature changes in the upper mixed layer and the atlantic layer, through inversion of the mode arrival times. the inherent low spatial resolution of the acoustic grid could be later improved with the addition of more sources and receivers. however, even the notional grid proposed could alert researchers to important changes anywhere in the entire arctic basin for more detailed ice-breaker and ice camp based research. in addition to the acoustic data, the observatories would be equipped with oceanographic, biological, chemical, sea ice and seismic sensors. this cabled network would provide coincident long term eulerian time series of all these measurements. propagation loss of acoustic signals in the arctic channel strongly depends on the thickness and roughness of the ice cover. this suggests a way to remotely observe variations of the average thickness of sea ice in the arctic (gavrilov & mikhalevsky 1995). together with satellite data on ice concentration, such measurements may allow us to obtain direct estimates of the volume of floating sea ice in the arctic ocean, which is one of the important climate variables. however, the accuracy of such remote sensing of sea ice thickness needs to be investigated in more detail and with experimental measurements. the notional network represents approximately 24 000 km of acoustic path length. to obtain by direct measurement of temperature an average temperature on these 18 acoustic paths that would be equivalent to the acoustic thermometry, it would require sampling along each path at the mesoscale correlation length of approximately 50 km. this would therefore require installing and maintaining a continuous presence of 600 1000 buoys equipped with at least a 1 km long thermister chain that must be mounted through the ice in locations that span the entire arctic basin or performing continuous ice-breaker or submarine transects, neither of which is economically or even physically possible for continuous samfig. 5. the computed travel time for mode 2 for the scicex 1995, 1998 and 1999 sections plotted against the average temperatures for the sections. note the almost linear correlation between the travel time for mode 2 and the average atlantic layer section temperature for the three years. the error bars shown for the computed travel time (vertical) and for the section average temperature (horizontal) are described in the text. 192 acoustic thermometry in the arctic ocean pling even on a seasonal basis. the accuracy of the submarine sampled section temperature average was shown to be approximately ± 0.6 m°c and the acoustic measurement is comparable or better with an accuracy of ± 0.9 m°c or ± 0.02 m°c for the waveform time and phase method respectively. acoustic thermometry provides a way to measure the average temperature of the arctic ocean water masses synoptically and continuously, unavailable by other means. conclusions the travel time of waveguide modes of a low frequency acoustic signal propagated in the arctic ocean is a precise measure of the average temperature in the main typical water layers along the acoustic path. the two acoustic sections of april 1994 and april 1999 detected basin scale warming in the atlantic water layer of the arctic ocean. these results have been confirmed by the scicex expendable ctd transects. under the acous program a 14 month time series has been collected and is currently being analysed. new technologies for synoptic, real-time, autonomous and unmanned operation are required if we are going to be able to make observations year-round on the spatial and temporal scales needed to understand the changes that are already occurring in the arctic ocean. a network of cabled-to-shore arctic moorings (3 sources and 6 receivers/observatories) would provide realtime year-round synoptic measurement of the average temperature of the atlantic layer and other important variables in the arctic ocean. acknowledgements.—the work was funded by the national science foundation (office of polar programs), the office of naval research (high latitude programs), the us civilian research and development foundation, and the ministry of science and technology of the russian federation. references carmack, e. c., aagaard, k., swift, j. g., macdonald, r. w., mclaughlin, f. a., perkin, r. g. & jones, p. e. 1995: the arctic is warming: results from the us/canada 1994 arctic ocean section. in: the abstracts of the xxi general assembly of iapso. honolulu, hi, august 1995. pp. 26–27. international association for the physical sciences of the oceans. dushaw, b., bold, g., chiu, c. s., colosi, j., cornuelle, b., desaubies, y., dzieciuch, m., forbes, a., gaillard, f., gould, j., howe, b., lawrence, m., lynch, j., menemenlis, d., mercer, j., mikhalevsky, p. n., munk, w., nakano, i., schott, f., send, u., spindel, r., terre, t., worcester, p. & wunsch, c. 2001 observing the ocean in the 2000s: a strategy for the role of acoustic tomography in ocean climate observation. in n. r. smith & c. j. koblinsky: observing the ocean in the 21st century. melbourne, australia: global ocean data assimilation experiment (godae) project office. ewg (environmental working group) 1997: joint u.s.– russian atlas of the arctic ocean (cd-rom). boulder, co: national snow and ice data center. gavrilov, a. n. & mikhalevsky, p. n. 1995: modeling an acoustic response to long-term variations of water and ice characteristics in the arctic ocean. proceedings of ieee oceans ‘95. vol. 1. pp. 247–253. san diego, ca: ieee. gavrilov, a. n., & mikhalevsky, p. n. 2001: mode coupling effects in acoustic thermometry of the arctic ocean. in m. taroudakis & g. makrakis (eds.): inverse problems in underwater acoustics. pp. 105–126. new york: springer. grotefendt, k., logemann, k., quadfasel, d. & ronski, s. 1998: is the arctic ocean warming? j. geophys. res. 103(c12), 27,679–27,687. johnson, m., proshutinsky, a. & polyakov, i. 1999: atmospheric patterns forcing two regimes of arctic ice–ocean circulation: a return to anticyclonic conditions? geophys. res. lett. 26, 1621–1624. lamont-doherty earth observatory 2001: website for scicex (scientific ice expeditions) at http://www. ldgo.columbia.edu/scicex/. manabe, s., spelman, m. j. & stouffer, r. j. 1992: transient response of a coupled ocean–atmosphere model to gradual change of atmospheric co2. j. clim. 5, 105–126. mikhalevsky, p. n., baggeroer, a. b., gavrilov, a. n. & slavinsky, m. 1995: experiment tests use of acoustics to monitor temperature and ice in the arctic ocean. eos trans. 76, 265–269. mikhalevsky, p. n., gavrilov, a. n. & baggeroer, a. b. 1999: the transarctic acoustic propagation experiment and climate monitoring in the arctic. ieee j. ocean. eng. 24, 183–201. munk, w. & forbes, a. m. g. 1989: global ocean warming: an acoustic measure. j. phys. oceanogr. 19, 1765-1778. pawlowicz, r., farmer, d., sotirin, b. & ozard, s. 1996: shallow-water receptions from the transarctic acoustic propagation experiment. j. acoust. soc. am. 100, 1482–1492. proshutinsky, a. y. & johnson, m. a. 1997: two circulation regimes of the wind-driven arctic ocean. j. geophys. res. 102(c6), 12,493–12,514. teague, w. j., carron, m. j. & hogan, p. j. 1990: a comparison between the gernalized digital environmental model and levitus climatologies. j. geophys. res. 95(c5), 7167–7183. teague, w. j., molinelli, e. j. & carron, m. j. 1987: a new system for management of the master oceanographic observation data set (moods). eos trans. 68, 558–559. worcester, p. f., peckham, d. a., hardy, k. r. & dormer, f. o. 1985: avatar: second-generation transceiver electronics for ocean acoustic tomography. in: proceedings oceans ‘85: ocean engineering and the environment. pp. 654–662. san diego, ca: ieee. research note diatoms from an ice-wedge furrow, ungava peninsula, quebec, canada lllsa koivo and matti seppala koivo, l. & seppala, m . 1994: diatoms from an ice-wedge furrow, ungava peninsula, quebec, canada. polar research 13(2), 237-241. the first recorded information about living fresh water diatoms on an ice-wedge furrow is presented. one sample has been analysed and two species, cymbella aequalis and tabellaria flocculosa, formed almost half of the diatom population. some rather rare species for the canadian eastern arctic were identified: fragilaria constricta, eunotia lunaris, eunotia microcephala, pinnularia gibba, anomoeoneis zellensis, and cymbella aspea. of the 37 species identified, most are common elsewhere in the arctic. liisa koivo. lahnaruohontie 4 c 37, sf-oozoo helsinki, finland; matti seppala, laboratory of physical geography, p . o . box 9, fin-00014 helsinki university, finland introduction in conjunction with a study of low-centred ice wedge polygons in august 1986, on the northern ungava peninsula, quebec, canada, (seppala et al. 1988) a water sample was collected from an ice-wedge furrow for algal analysis. the bottom of the shallow water body was totally covered by a brownish red layer formed mainly by oscillatoria and desmidiaceae green algae (seppala et al. 1991). the sample was also enormously rich in diatoms. because of the remoteness of the location and the lack of information in the literature about fresh water diatoms in ice-wedge furrows, it was considered worthwhile to identify the species more carefully. the results were then compared with other investigations from the eastern canadian arctic as well as from greenland, fen noscandia, spitsbergen and alaska. it is well known that diatoms live on, in and under the sea ice in the arctic (e.g. meguro et al. 1966; horner & schrader 1982; horner et al. 1988; syvertsen 1991) and in antarctic waters (meguro 1962). one of the main questions raised in these studies has been how the algae survive the winter: do they remain inactive in the ice or d o they produce resting spores for winter survival in the water or o n the sea floor. another question is whether or not diatoms penetrate into the sea ice pores. answers to these questions are also fundamental when considering the diatom con tents of permafrost ice. although this study has not been able t o provide the answers, we would like to point out that in the continuous permafrost zone a rich diatom flora can be found in shallow waters which are unfrozen for only a few months and frozen to the bottom for about ten months of the year. these diatom-rich waters may affect the permafrost layers underneath, at least through the frost cracks. sampling site, material and methods the polygon field is situated in the northernmost ungava peninsula on the flood-plain terrace of the rivitre dbception 62"07'30''n, 74"17'30'w, about 50 m a.s.1. and 35 km from the present coast of hudson strait. the field lies in the immediate vicinity of a large sub-aqueous glacio-marine out wash fan described by gray et al. (1985) and ricard et al. (1987), some seven metres above the normal summer level of rivitre dcception. the region is 500 km north of the timber line and belongs to a zone of continuous permafrost (fig. 1). the permafrost may attain a thickness of 600 m (taylor & judge 1979). the main annual air temperature is -8°c. precipitation data are not available. snow depths range from 20 t o 40 cm in general (seppala et al. 1991). the low-centred ice-wedge polygons with 70 80 cm high marginal banks form tetragonal pat 238 liisa koiuo and matti seppala sc hellerv'lle q u e b e c fig. 1. general location of the sampling site. terns averaging 20 m in diameter (seppala et al. 1991). the maximum width of the polygon banks on each side of a deep fissure is about 2,5 m. ice-wedges exist in the middle of the banks on average 24 cm below the active layer (seppala et al. 1988). on the active layer above the ice-wedge up to 1,5 m wide furrows are located which could be filled with standing fresh water formed by melting and rain. the bottom layer on the algal mat from one of these furrows was sampled for diatom analyses on 12 august 1986. the depth of that water body was 25 cm with a ph value of 6.6. the water temperature in the ice-wedge furrow was not measured. for comparison we can tell that the maximum water temperature (+15.6"c) of the river rivikre dbception was recorded on 1 august 1986. this is higher than the temperature of the water just above the permafrost. the study period from the 1-16 august was warm with the highest recorded air temperature of +26.8"c. on 5 august 1986 at five o'clock in the morning the lowest air temperature of -4.7"c was measured. during the following days the air temperature ranged between +1.7 and +12.7"c. the sample was taken from the green algae mucus into a 5001111 plastic bottle. before the preparation of the diatom slide the sample was kept cold and 5 ml of strong formaldehyde was added for preservation. normal decanting tech niques and centrifugation were used in the prep aration of the sample. two hundred diatom frustules were counted in the systematic quantitative analysis, and after that an overall view of the sample was taken and the quality of all species were identified. a paper by ross (1947) on freshwater diatoms in the eastern canadian arctic was used as the main reference. other valid references are cleve (1864), cleve & grunow (1880)) hustedt (1930), patrick & freese (1961), and seidenfaden (1947). results quantitative analysis of diatoms two species, cymbella aequalis and tabellaria flocculosa, constituted almost half of the diatom population in the sample (table 1). other com mon species were fragilaria constricta, nitzschia amphibia, cymbella argustata u. hybrida. in total these five species formed 65% of the 200 counted frustules . twenty-three species were found in the quan titative analysis (table 1). four of these were recognised just once. ecology of the species most of the identified species are classified as halophobe or oligohalobe, and according to foged (1981), the ph of their living habitat is circumneutral, indifferent, or they are acido philous species. some alkaliphilous species (achnanthes minutissima var. cryptocephala, cymbella aspera, c . turgida, nitzschia amphibia, n. frustulum) were also identified (cf. foged 1981). the life habitat of these species seems to be truly benthic because the maximum water depth was only 25cm and the sample was col lected from the bottom. discussion distribution comparisons six species (fragilaria constricta, eunotia lunaris, eunotia microcephala, pinnularia gibba, ano moeoneis zellensis, cymbella aspera) found from the ungava peninsula were not mentioned by ross (1947) as coming from the eastern canadian arctic. fragilaria constricta is the third most common species in this sample from ungava peninsula, but it is mentioned in arctic literature only as a rare species from varanger peninsula, norway diatoms from an ice-wedge furrow 239 table 1 . quantitative analysis of freshwater diatoms, ungava peninsula, northern quebec, canada (62"07'3(y'"n 74"17'3(yw). comparable distribution data: cea (canadian eastern arctic; ross 1947); pl (peary land, northern greenland; foged 1955); wg (west greenland; foged 1958); sp (spitsbergen; foged 1964); v (varanger peninsula, norway; foged 1968); fl (finnish lapland: seppiila 1971); a (alaska; foged 1981). n % cea 1. nirrschia amphibia gnnow 11 5.5 + 2. n . frustulirm (kiitz.) grunow 3 1.5 + 4. p. microsrauron (ehrenb.) cleve 9 4.5 + 5. p. gibba ehrenberg 1 0.5 6. p. borealis ehrenberg 3 1.5 + 7. p. diuergentissimn (gnnow & van huerck) cleve 2 1.0 + 8. tabellaria flocculosa (roth) kiitzing 40 20.0 + 11. c . turgida gregory 4 2.0 + 12. c. aspera (ehr.) cleve 2 1.0 13. c . angustata v . hybrida (gnnow ex. a. smith) 10 5.0 + 14. anomoeoneis zel1en.m (gnn.) cleve 2 1.0 3. pinnularia mesolepta (ehrenb.) w. smith 6 3.0 + 9. t. fenestrata (lyngb.) kiitzing 6 3.0 + 10. cymbella aequalis w. smith 51 25.5 + 15. stauroneis phoenicenteron v.x (nitzsch) kiitzing 8 4.0 + 16. s . anceps v. amphicephala (kiitz.) cleve 5 2.5 + 17. eunotia septenrrionalis 0strup 5 2.5 + 18. e. lunaris (ehr.) grunow 8 4.0 19. e. monodon ehrenberg 1 0.5 + 20. e . praerupta ehrenberg var.x 3 1.5 21. e. tenella (grunow) hustedt i 0.5 + 22. e . pecrinalis var. minor ( k u t z . ) rabenhorst 1 0.5 + 23. fragilaria constricta ehrenberg 18 9.0 total 200 100% in addition to the species above the following taxa were determined in the qualitative analysis: 24. synedra tabulara var. delicatula (gnnow) cleve & gnnow 25. eunotia praerupta var. genuina gnnow & van huerck 26. eunotia exigua (brkb. ex kiitz.) rabenhorst 21. eunotia pseudoparallela a. cleve-euler 29. achnanrhes minutissima var. cryptocephala grunow & van huerck 30. nauicula uariabilis var gomphonemacea grunow & van huerck 32. neidium iridis var.? (ehrenb.) cleve 33. stauroneis perplrsilla var obtwiutculn gnnow 34. gomphonema micropus kiitzing + 35. cymbella microcephala gnnow & van huerck 36. cymbella stauroneisformis lagerstedt + 37. cymbella botellus (?) (lagerstedt) a. schmidt + + + + 28. eunoria microcephala krasske + + + + + 31. nauicula rotaeana grunow & van huerck + + pl wg sp v fl a + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + i + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + i + + + + + + + + + + + + + + + + + + + + + + ' + + + i + + + + + i + (foged 1968) and from adak island, aleutian islands (hein 1990, p. 52). two of the common species (cymbella aequalis and stauroneis anceps var. amphicephala) and six of the rare species (eunotia praerupta var. genuina, e . pseudoparallela, nauicula uariabilis var. gomphonemacea, stauroneis perpusilla var. obtusiuscula, gomphonema micropus, and cym bella botellus) from the ungava peninsula have been found elsewhere in the eastern canadian arctic by ross (1947), but these have not been mentioned in other checked studies from the arc tic. most of the species (except cymbella aequalis, and stauroneis anceps v. amphicephala) men tioned in the quantitative analysis (table 1) have been found and are also common on the varanger peninsula, northern norway (foged 1968). seven of the additional species identified in the quali tative analysis are missing from the varanger peninsula (table 1). twenty-four species listed from the ungava peninsula have also been found in west green land by foged (1953; 1958). twenty-one species are also mentioned from peary land, north ernmost greenland (foged 1955). 26 species from 240 liisa koiuo and matti seppala alaska (foged 1981), and 23 species from spits bergen (foged 1964) (table 1). picinska-faltynowicz (1988), in her study from southern spitsbergen, mentioned twelve of the diatom species listed in this article from the ungava peninsula, including cymbella turgida which foged (1964) did not find in the small lakes of spitsbergen (picinska-faltynowicz 1988, table on adak island in the northern pacific, hein (1990) mentioned only two of our mentioned species as common (eunotia pectinalis var. minor and tabellaria flocculosa). he found thirteen other species listed in this study as rare, very rare or infrequent on adak island. all had already been found by foged (1981) in alaska (table 1). as a small comparison to subfossil material from finnish lapland, one sample is listed as coming from the bottom of a mire (table 1) which was formed some 8000 years ago from a small pond (seppala 1971, fig. 37, table 14). six species from this lappish sample have also been found in the ungava peninsula. many fresh water diatoms in our sample are cosmopolite and can be found throughout the arctic regions. our analysis confirms that even small water bodies which are deeply frozen most of the year can be very rich in diatom flora. as little is known about the diatom flora of small seasonal water bodies on permafrost, it is hoped that this study will serve as an impetus to further diatom studies from permafrost ice. the survival strategies of diatoms in permafrost environments should be studied with the aid of year-round observation. we d o not know if any of the dominating species of this study produce resting spores or resting cells, one possible way of surviving the winter. another open question arising from our observations is the length of the summer season (=thawing season) needed for the development of such a rich diatom flora. the comparisons of diatom floras in ungava and lapland correspond well with the supposition that the climate of northern fennoscandia after deglaciation has not been as severe as that in the canadian arctic today. only six species were found in both regions. based on studies of diatoms in the literature, the climate of northern fen noscandia at the end of boreal time need not have differed greatly from the present-day climate which is subarctic in this southern margin of the discontinuous permafrost zone. 3). acknowledgements. -the sample was collected during the 1986 expeditionorganised by j. gray, universitc de montreal. green algae were determined by v. hosiaisluoma. the travel costs of m. seppala were financed by the national council of natural sciences, finland. we are also very grateful to twd anonymous referees for comments which improved the manuscript and to n. o’donoghue for checking the english language. references cleve, p. t. 1864: diatomaceer fran spetsbergen. ofuersigr af vet. akad. forhandl. 10, 661671. cleve, p. t. & grunow, a. 1880 beitrage zur kenntniss der arktischen diatomeen. kungl. suenska vetenskaps akad. handl. 17(2). 121 pp. +7 tables. foged, n. 1953: diatoms from west greenland. medd. om gronland 246(10). 86 pp. +xi11 plates. foged, n. 1955: diatoms from peary land, north greenland. medd. om gronland 128(7). 90 pp. +xiv plates. foged, n. 1958: the diatoms in the basalt area and adjoining areas of archean rock in west greenland. medd. om gron land i56(4). 146 pp. +xvi plates. foged, n. 1964: freshwater diatoms from spitsbergen. t r u m o museum skrifter x i , 1-205. foged, n. 1968: the freshwater diatom flora of the varanger peninsula, north norway. acta borealia. a . scicntia 25, 1 64. foged, n. 1981: diatoms in alaska. bibliotheca phycologica 53. 317 pp. +64 plates. gray, j . t., lauriol. b. & ricard, j . 1985: glacio-marine outwash deltas, early ice retreat and stable ice fronts in the north-eastern coastal region of ungava. pp. 150-153 in: arctic land sea interaction, abstracts of 14th arctic workshop, bedford institute of oceanography. hein, m. k. 1990: flora of adak island, alaska: bacil lariophyceae (diatoms). bibliotheca diarumologica 21. 133 pp +53 plates. horner, r. a. & schrader, g. c. 1982: relative contributions of ice algae, phytoplankton and benthic microalgae to primary production in nearshore regions of beaufort sea. arctic 35, 485-503. homer, r. a., syvertsen, e. e.; thomas, d. p. & lange, c. 1988: proposed terminology and reporting units for sea ice algal assemblages. polar b i d . 8, 249-253. hustedt, fr. 1930: bacillariophyta (diatomeae). in: die suss wasser-flora mineleuropas 10. pascher. jena. 466 pp. meguro, h. 1962: planktonice in the antarctic ocean. antarctic record 14. 1192-1199. meguro, h.; ito, k. & fukushima, h. 1966: diatoms and the ecological conditions of their growth in sea ice in the arctic ocean. science 152, 1089. patrick, r. & freese, l. r. 1961: diatoms (bacillariophyceae) from northern alaska. proc. acad. nut. sci. philadelphia 112: 6 . 129-293. f’icinska-faltynowicz, j. 1988: freshwater benthic diatoms from the south-western part of the hornsund fiord area, sw spits bergen. polar res. 6, 1%34. ricard, j . , gray, j . t. & lauriol, b. 1987: la dkglaciation et i’cmergence des terres pr&s de la rivisre deception, pen insula d’ungava. nouveau-quebec. 12th inqua congress abstracts, ottawa, canada. p. 252. ross, r. 1947: freshwater diatomeae (bacillariophyta) in polunin, n . v. (ed.):. botanyofthe canadianeastern arctic. part 11. nut. mus. canada bull. 97, 178-233. seidenfaden, g. 1947: marine phytoplankton. nut. mus. can ada bull. 97. 138-177. seppala, m. 1971: evolution of eolian relief of the kaamasjoki kiellajoki river basin in finnish lapland. fenniu 104, 1-88. seppala, m.. gray, j . & ricard, j . 1988: the development of depressed-centre ice-wedge polygons in northernmost ungava peninsula, quebec, canada. pp. 862-866 in senne diatoms from an ice-wedge furrow 241 set, k. (ed.): permafrost fifth international conference pro ceedings, aug. 2-5. 1988, trondheim. seppala. m . . gray, j. & ricard, j. 1991: development of low-centred ice-wedge polygons in the northernmost ungava peninsula. quebec. canada. boreus 20, 259-282. syvertsen. e. e. 1991: ice algae in the barents sea: types of assemblages, origin, fate and role in the ice-edge phy toplankton bloom. polar res. 10, 277-287. taylor, a . & judge, a. 1979: permafrost studies in northern quebec. gkographie physique et quuternaire 33. 245-252. pavlov.indd 153pavlov 2001: polar research 20(2), 153–160 seasonal and long-term sea level variability in the marginal seas of the arctic ocean vladimir k. pavlov one of the parameters useful for monitoring large-scale climate variability in the arctic ocean is sea level. it integrates virtually all static and dynamic processes in the hydrosphere and atmosphere of the arctic. previously unavailable mean monthly sea level data at 44 coastal and island stations in the kara, laptev, east siberian and chukchi seas covering years from 1950 to 1990 were used to analyse seasonal and inter-annual variability. sea level has a significant annual cycle with an average seasonal amplitude (from peak to peak) in the coastal zone of the arctic seas on the order of 20 30 cm. the analysis of inter-annual and inter-decadal changes has shown that at nearly all stations in the kara, laptev, east siberian and chukchi seas from the beginning of the 1950s through the end of 1980s there is a positive trend in sea level variability. the main contribution to the sea level rise was in the 1980s; on average for the coastal zone of siberian shelf the sea level in the 1980s was 5 6 cm higher than in the previous decades. a reasonable agreement between observed decadal mean sea level values and the results of diagnostic model simulations suggests that this rise in the arctic seas is connected with the reorganization of large-scale circulation of the arctic ocean, rather than the regional lowering of the coasts, as has been suggested previously. v. k. pavlov, norwegian polar institute, polar environmental centre, n-9296, tromsø, norway. influenced by the integration of a number of physical processes in the environment, sea level can serve as a representative parameter for monitoring climate changes in the arctic (pavlov & stanovoy 1997). the major factors shaping sea level variability are changes in water density, the reorganization of the thermohaline circulation and the modification of atmospheric dynamics. seasonal and inter-annual sea level variability was analysed using a virtually continuous 40-year (1950–1990) time series of mean monthly data at 44 island and coastal stations in the kara, laptev, east siberian and chukchi seas (table 1). these stations are irregularly distributed over the coastal zone of the russian arctic seas. the largest number of stations was located in the kara sea; the fewest were in the chukchi sea. only those chukchi sea stations located in the russian coastal zone were subject to analysis. tide gauges at most coastal and island stations were not connected with the geodetic network, and therefore only relative sea level values were measured at these stations. in the analysis of seasonal and inter-annual variability, we have first removed the mean sea level value for each station, calculated over the entire period of observations. previous analyses of seasonal and inter-annual sea level variation have been conducted for different siberian shelf stations by dvorkin et al. (1978), pavlov (1998) and pavlov & pavlov (1999). however, dvorkin et al. (1978) used observations up to the mid-1970s, so their results did not take into account modern sea level trends. pavlov (1998) and pavlov & pavlov (1999) have conducted a similar analysis for only selected stations in the laptev and east siberian seas. 154 seasonal and long-term sea level variability results seasonal variability figure 1 shows typical examples of seasonal variability of the monthly mean sea level in the coastal zone of the siberian marginal seas. at all the stations the minimum values were observed in april. sea level sharply increases from may, reaching its maximum values in summer and autumn. in the kara sea the absolute sea level maximum is observed in june or july at most stations located along the siberian coast and especially near river mouths (fig. 1). some stations have annual absolute maxima in october or december. however, these stations also show local maxima in the summertime. it was shown by pavlov & pavlov (1999) that extreme values were related to the appearance of a baroclinic coastal current in summer. the summertime baroclinic coastal current is not only a local phenomenon of the kara sea but an important feature of the water circulation in all the siberian seas (weingartner et al. 1999; pavlov 2001a). this current is caused by large density gradients because of fast ice melting and increased freshwater inflow. high correlation between sea level and water density throughout the year (pavlov & pavlov 1999) suggests that the main contribution to the seasonal cycle of sea level variations results from changes of the thermohaline conditions and the related steric expansion and reorganization of the general circulation in the arctic ocean. calculation of the monthly mean steric sea level at the station near enisey bay, based on annual observations of temperature and salinity which were carried out in 1961, shows good agreement with the observed sea level for the may–september period (pavlov 2001b). the amplitude (from peak to peak) is close to the observed amplitude at the nearest station, dikson. this implies that the major cause of the dramatic increase of the sea level near the mouths of the big siberian rivers in june–july is steric expansion resulting from increased river discharge at this time (which our observations suggest is caused by increased snowmelt due to higher spring–summer temperatures). the main contribution to steric expansion (about 90 %) is the reduction of salinity in summertime. the extremes in autumn through early winter are caused by intensification of atmospheric circulation over the arctic ocean in that period of the year. the mean amplitude (from peak to peak) of the seasonal sea level oscillations in the kara sea is 21.4 cm. the maximum amplitude was 33.7 cm and was observed at the ust-kara station. seasonal variability in the laptev sea is nearly the same as in the kara sea. minima are observed in april and maxima in june, july or october fig. 1. seasonal sea level variability in the kara, laptev, east siberian and chukchi seas. geographical locations are given in table 1, in accordance with the numbers used here. 155pavlov 2001: polar research 20(2), 153–160 depending on the region (fig. 1). in contrast to the kara sea, the december maximum is completely absent in the laptev sea. the mean amplitude of the annual sea level cycle in the laptev sea is 23.4 cm. the maximum amplitude of 32.6 cm was observed at the kosistiy station. the absence of the absolute october sea level maximum in the east siberian sea (fig. 1) is a specific feature of this region. local maxima were observed at some stations in october. the absolute maximum at all the stations is observed in july. the minimum sea level values are observed, as in the previous cases, in april. the mean sea level amplitude in the east siberian sea was 29.8 cm. the maximum amplitude (42.2 cm) was observed at the ambarchik station. stations in the chukchi sea show an absolute sea level maximum in october (fig. 1). small local extrema were observed at the netten and shmidt stations in june and july. the mean amplitude of the annual sea level cycle in the chukchi sea is 31.0 cm. the maximum amplitude of 33.7 cm was observed at the vankarem station. figure 2 shows the geographical variation in the seasonal sea level amplitude. maximum values of the amplitude are observed along the western coast of the kara sea, in bays and gulfs of the laptev sea, along the eastern coast of the east siberian sea and in the western chukchi sea. the minimum amplitude of seasonal variability is observed at the island stations in the northern kara and laptev seas. the amplitude of seasonal variability in the arctic seas appears to depend on latitude (fig. 3). the maximum amplitudes occur in the southernmost regions, with minima observed at stations further to the north. a possible explanation for this is the stronger steric expansion of sea level in southern regions due to strong freshwater and warm-up of water masses in summer. table 1. names, geographical locations and time periods of the observational stations in the coastal zone of the kara, laptev, east siberian and chukchi seas. station observation longitude latitude time no. stations (n) (e) period 1 bolvanskiy nos 59.06 70.45 1951–1987 2 yugorskiy shar 60.75 69.81 1950–1987 3 zhelaniya 63.56 76.95 1951–1985 4 ust kara 64.51 69.25 1950–1989 5 kharasovey 66.81 71.13 1954–1992 6 amderma 61.68 69.77 1950–1987 7 vize 76.98 79.50 1953–1989 8 dikson (bay) 80.40 73.50 1950–1989 9 uedineniya 82.23 77.50 1953–1989 10 izvestiya cec 83.08 75.53 1954–1989 11 sterligova 88.90 75.53 1950–1989 12 isachenko 89.20 77.15 1954–1989 13 golomjaniy 90.61 79.55 1954–1989 14 pravdy 94.28 76.26 1950–1989 15 russkiy 96.43 77.16 1951–1980 16 krasnoflotskie 98.71 78.63 1954–1987 17 geyberg 101.51 77.60 1951–1989 18 solnechnaya 103.26 78.20 1951–1989 19 cheliuskin 104.28 77.71 1950–1985 20 maliy taimyr 106.81 78.08 1950–1990 21 kosistiy 109.73 73.66 1954–1989 22 andrey 111.45 76.81 1951–1990 23 preobrazheniya 112.93 74.66 1951–1990 24 terpiay-tumsa 118.66 73.53 1956–1990 25 dunay 124.50 73.93 1951–1987 26 tiksi 128.91 71.58 1949–1990 27 muostakh 130.01 71.55 1951–1990 28 kotelniy 137.90 76.00 1951–1990 29 sannikov 138.90 74.66 1950–1990 30 kigiliakh 139.88 73.35 1951–1990 31 sviatoy nos 140.73 72.83 1951–1987 32 bunge land 142.11 74.88 1951–1987 33 shalaurova 143.93 73.18 1950–1990 34 zhokhova 152.83 76.15 1959–1990 35 ambarchik 162.30 69.56 1950–1991 36 chetyrokh166.58 69.51 1951–1991 stolboviy 37 rua-chau 166.58 69.51 1950–1989 38 ayon 167.98 69.91 1954–1991 39 pevek 170.60 69.75 1950–1991 40 billingsa 175.76 69.88 1953–1991 41 shmidt cape 180.51 68.91 1950–1990 42 vankarem 184.16 67.83 1950–1991 43 koluchin 185.36 67.48 1950–1991 44 netten 188.06 66.95 1950–1991 fig. 2. spatial variations in amplitude (from peak to peak) of the annual cycle of the sea level. 156 seasonal and long-term sea level variability inter-annual variability positive trends in inter-annual sea level variability at the almost all stations in the coastal zone of the marginal arctic seas were observed from the beginning of the 1950s until the end of the 1980s (table 2). trends of decreasing annual mean sea levels were observed at only three of the 44 stations: zelania in the kara sea, kigiliakh and kosistiy in the laptev sea in the same period. the negative trend at these stations could be explained by local uplift connected with the geological processes in that region or by instrumental errors of observations. unfortunately, insufficient information about local environmental conditions and methods of observations prevents us from offering a precise explanation of such sea level variability at these three stations. figure 4 shows typical examples of inter-annual variability of the annual mean sea level in the coastal zone of the marginal seas of the siberian shelf. the magnitudes of inter-annual variability of the annual mean sea level values in the kara and laptev seas are comparable with the amplitudes of the seasonal variation. in the east siberian and chukchi seas, inter-annual variability is greatest, reaching 40 cm and more. in the three decades spanning the beginning of the 1950s to the end of the 1970s, the positive sea level trend was not as pronounced as it was in fig. 3. the annual amplitude of sea level plotted against the location (latitude) of observational station. table 2. linear trends of the inter-annual sea level variation and anomalies in the kara, laptev, east siberian and chukchi seas. anomalies for each station were calculated as deviations from mean (for four decades) sea level. geographical locations are given in table 1. coefficients of sea level anomalies (cm) stations the linear trend 1950–1989 1950s 1960s 1970s 1980s kara sea amderma 0.03 -1.80 1.18 -0.70 1.32 bolvanskiy nos 0.07 -0.98 0.42 -1.82 2.39 cheluskin 0.07 -0.89 0.73 -2.21 3.36 solnechnaya 0.46 -7.82 -0.36 -0.52 8.70 dikson 0.00 -0.89 1.04 -0.67 0.53 geyberga 0.19 -3.16 0.19 -1.41 4.39 zhelaniya -0.43 -0.96 4.47 -2.18 -3.51 golomyaniya 0.06 -2.97 2.70 -2.68 2.95 kharasovey 0.17 -4.26 0.32 -2.74 6.67 isachenko 0.35 -1.47 -2.44 1.26 2.65 izvestiy cec 0.10 -2.05 0.64 -0.1 1.41 krasnoflotskaya 0.22 -3.71 0.00 -0.27 3.98 pravdi 0.25 -3.62 0.08 -2.89 6.43 sterligova 0.17 -2.35 -0.18 -1.75 4.26 yugorskiy shar 0.14 -0.94 1.08 -0.86 0.72 uedineniya 0.03 -3.84 1.22 1.28 1.35 ust-kara 0.06 0.01 -0.67 -1.38 2.06 vize 0.06 -0.88 0.58 -1.36 1.66 averaged 0.111 -2.316 0.626 -1.162 2.851 laptev sea andrey 0.33 -6.60 0.62 0.87 5.10 dunay 0.09 -0.42 -0.69 -2.54 3.64 kigilyakh -0.04 3.32 -1.00 -3.15 0.84 kosistiy -0.71 3.94 3.45 -10.45 3.06 kotelniy 0.48 -8.06 -0.73 1.22 7.57 maliy taymir 0.24 -5.04 0.67 -0.39 4.76 muostakh 0.31 -3.47 0.20 0.43 3.70 preobrageniya 0.07 -0.90 0.17 0.68 1.41 sannikova 0.06 0.23 -0.68 -1.60 1.43 sviatoy nos 0.21 -1.89 -1.37 -3.70 6.95 terpiya tumsa 0.23 -3.42 0.24 -0.64 3.81 tiksi 0.14 -1.26 -0.49 -1.37 3.13 averaged 0.123 -1.963 0.084 -1.904 3.783 east siberian sea cheryriokh0.11 3.54 -3.35 -4.74 4.55 stplboviy ambarchik 0.2 1.08 -4.41 -2.70 6.02 ayon 0.00 5.88 -2.39 -5.86 2.37 billingsa 0.15 3.32 -3.81 -4.13 4.62 bunga 0.23 -2.89 -1.20 0.36 3.73 zhokhova 0.17 4.08 -1.50 -5.32 2.73 pevek 0.21 1.44 -4.28 -2.86 5.69 rua-chau 0.05 3.83 -4.00 -3.93 4.10 shalaurova 0.05 0.70 1.23 -2.28 0.35 averaged 0.130 2.331 -2.633 -3.495 3.796 chukchi sea koluchin 0.52 -2.72 -7.16 0.14 9.74 netten 0.33 -3.35 -1.95 -3.15 8.45 shmidt cape 0.32 -2.8 -0.30 -3.60 6.70 vankarem 0.50 -6.82 -3.12 -1.12 11.05 averaged 0.418 -3.921 -3.131 -1.931 8.984 157pavlov 2001: polar research 20(2), 153–160 the 1980s. the majority of the kara sea stations and only half of the laptev sea stations have positive trends in this period of the 1950s through the 1970s. however, averaged trends for the kara and laptev seas were positive as well (0.07 cm/year and 0.06 cm/year for kara and laptev seas, respectively). for calculations of the averaged trends in the kara and laptev seas we did not use data from stations zelania, kigiliakh and kosistiy because their quality is doubtful, as is mentioned above. almost all stations in east siberian sea show a negative trend (-0.219 cm/year on average) over the 1950s–1970s. in contrast, all the chukchi sea stations showed a positive trend in this period (0.108 cm/year on averaged). in the kara sea (table 2) in the 1950s, the negative anomaly of the sea level was -2.32 cm on average. in the 1960s the sea level increased on average by 3 cm and in the kara sea there was a weak (0.63 cm) positive sea level anomaly. in the 1970s the level of the kara sea again lowered and the negative anomaly reached on average -1.16 cm. in the 1980s, the sea level rise was more than 4 cm and the positive anomaly in this decade reached the maximum value (2.85 cm). a similar pattern occurred in the laptev sea, with the only difference that in the 1980s the sea level there increased more significantly (by nearly 6 cm) compared with the previous decades. in the east siberian sea the positive anomaly that was observed in the 1950s was replaced with a negative one in the next two decades. but in the 1980s there was a sharp sea level increase (more than 7 cm). in the chukchi sea the negative sea level anomalies were preserved during the three decades from the 1950s through the 1970s. in the 1980s, the sea level rose (nearly 11 cm on average) and the positive anomaly became 8.98 cm. cal fig. 4. seasonal variability of sea level (thin line) and the linear trend (bold line) in the kara, laptev, east siberian and chukchi seas. geographical locations are given in table 1, in accordance with the numbers used here. fig. 5. anomalies of the annual mean sea level when cyclonic (solid line) and anticyclonic (dashed line) regimes prevail. values indicate correlation coefficients between winter nao index and sea level in february. 158 seasonal and long-term sea level variability culation of the decadal sea level anomalies and trends therefore reveal that an especially strong sea level increase in the coastal zones of all the siberian shelf seas was in the 1980s (table 2). discussion what is the reason for such a pattern of longterm variability of the sea level in the marginal arctic seas? major aspects of the sea level change problem, methods of sea level change detection, modelling and interpretation of sea level variability are discussed in publications by pugh (1987), national research council (1990), emery & aubrey (1991), woodworth et al. (1992), baker (1993), woodworth (1993), gornitz (1995), peltier (1999) and many others. most of the stations in the arctic ocean show a significant sea level rise. this sea level increase could be a manifestation of global warming in the arctic, together with a decrease of sea ice extent (johannessen et al. 1999) and ice thickness (rothrock et al. 1999), air temperature rise (see ipcc at www.ipcc.ch; fig. 6. decadal mean anomalies of the sea level (cm) of the arctic ocean (modelling results) for the 1950s, 1960s, 1970s and 1980s. 159pavlov 2001: polar research 20(2), 153–160 levitus et al. 2001), warming of atlantic waters (morison et al. 1998; steele & boyd 1998), increased river runoff and atmospheric circulation changes (see www.ipcc.ch). the positive trend of sea level increase in the arctic seas was noted earlier by dvorkin et al. (1978). analysing data from the most representative stations along the siberian coast, dvorkin et al. explain the increase by suggesting that the arctic seas’ coasts are lowering. this is not supported by the results of the present study, which shows that there are opposite trends at some stations in some months. the trend of sea level increase in the arctic seas can be more correctly explained by changes in the water properties and large-scale circulation of the arctic ocean. shpaykher et al. (1972) proposed that physical processes (including sea level) strongly depend on the circulation of the arctic ocean. figure 5 shows that due to the dominance of the cyclonic circulation above the arctic ocean, the sea level in the laptev, east siberian and chukchi seas is high and the level in the kara sea is low. in years when the circulation is predominantly anticyclonic there is an opposite situation. however, the analysis of the relationship between winter north atlantic oscillation (nao) index and interannual sea level elevations in the arctic seas has shown that the correlation coefficients are significant, but not high (fig. 5). at the same time, in barentsburg on fram strait, where the barotropic circulation dominates (verduin 1999), the correlation coefficient between winter nao index and sea level elevations is high (r = 0.78) according to our calculations. recently, the contributions of wind and baroclinic components of the circulation to inter-annual variability of sea level in the laptev sea were analysed in pavlov & pavlov (1999). it showed that the baroclinic component predominates. to estimate the contribution of baroclinic circulation into the long-term variability of the sea level of the marginal arctic seas, mean decadal fields of level using a numerical model were simulated (pavlov & pavlov 1999). for the diagnostic simulation, mean decadal 3-d fields of water temperature and salinity of the arctic ocean for the years 1950–1980 (arctic cliomatology project 1998) were used. figure 6 shows the anomalies of the sea level for each of four decades (1950s, 1960s, 1970s and 1980s) obtained from the model. the highest positive anomaly in the 1980s is located in the marginal seas along the siberian coast. the maximum positive trend (about 8 cm for 40 years) is in the northern parts of the east siberian and chukchi seas. there is a compensating negative sea level anomaly over the continental slope. the maximum negative trend is located fig. 7. correlation between observed and calculated values of decadal mean sea level at the observational points. fig. 8. inter-decadal variability of the average sea level for the kara, laptev, east siberian and chukchi seas: observed, solid line; modelled, dashed line. 160 seasonal and long-term sea level variability in the northern part of the laptev sea. the comparison between simulated and observed mean decadal sea level at 44 coastal and island stations in the arctic seas shows very good agreement (fig. 7). the typical feature of the sea level’s inter-decadal variability is the sharp increase of the sea level in the shelf zone of the kara, laptev, east siberian and chukchi seas (fig. 8). in the kara sea during the 1980s, the level also increased, but not as significantly as in more eastern regions of the arctic ocean. conclusion the sea level in the coastal zone of the marginal seas of the arctic ocean has a significant annual cycle. the amplitude (from peak to peak) of the seasonal sea level variability is 20 30 cm on average. the good agreement between observed decadal mean values of the sea level and the results of diagnostic simulations gives grounds to believe that the tendency of the sea level rise in the arctic deas in the 1980s is connected with changes in the large-scale circulation of the arctic ocean. acknowledgements.—the author would like to express his appreciation to dr. james h. morison from the applied physics laboratory, university of washington, for helpful suggestions and comments on this study. part of this work has been supported by the office naval research (crdf/gap 20.97), grant rg0-633 and by the norwegian research council (nfr), grant 142132/720. references arctic climatology project 1998: environmental working group joint u.s.–russian atlas of the arctic ocean—summer period. l. timokhov & f. tanis (eds.). ann arbor, mi: environmental research institute of michigan in association with the national snow and ice data center. cd-rom. baker, t. f. 1993: absolute sea level measurements, climate change and vertical crustal movements. glob. planet. change 8, 145–149. dvorkin, e. n., zakharov, y. v. & mustafin, n. v. 1978: prichini sezonnoy i mnogoletney izmenchivosti urovnya laptevih i vostochno sibirskogo morey. (the causes of seasonal and inter-annual variability of the level of the laptev and east siberian seas.) aanii trudy 349, 60–68. leningrad: gidrometeoizdat. (in russian.) emery, k. o. & aubrey, d. g. 1991: sea levels, land levels, and tide gauges. new york: springer. gornitz, v. 1995: monitoring sea level changes. clim. change 31, 515–544. johannessen, o. m., shalina, e. v. & miles, m. w. 1999: satellite evidence for an arctic sea ice cover in transformation. science 286, 1937–1939. levitus, s., antonov, j. i., wang, j. l., delworth, t. l., dixon, k. w. & broccoli, a. j. 2001: anthropogenic warming of earth’s climate system. science 292, 267–270. morison, j., steel, m. & anders, r. 1998: hydrography of the upper arctic ocean measured from the nuclear submarine u.s.s. pargo. deep-sea res., i, 45, 15–38. national research council 1990: national research council (nrc) report on sea level change. washington, d.c.: national academy press. pavlov, v. k. 1998: features of the structure and variability of the oceanographic processes in the shelf zone of the laptev and east-siberian seas. in a. r. robinson & k. h. brink (eds.): the sea. the global coastal ocean, regional studies and synthesis. vol. 11, pt. 2: regional oceanography. pp. 759–787. new york: john wiley and sons. pavlov, v. k. 2001a: features of seasonal and interannual variability of the water circulation and sea level of the arctic ocean. extended abstracts of the second wadati conference on global change and polar climate, tsukuba, japan, 7–9 march 2001, 43-46. pavlov, v. k. 2001b: seasonal and long-term variability of the sea level in the marginal seas of the arctic ocean. extended abstracts of the cost action 40 final workshop, dubrovnik, croatia, 19–21 september 2001. pavlov, v. k. & pavlov, p. v. 1999: features of seasonal and interannual variability of the level regime and water circulation in the laptev sea. in h. kassens et al. (eds.): land– ocean systems in the siberian arctic: dynamics and history. pp. 3–16. berlin: springer. pavlov, v. k. & stanovoy, v. v. 1997: climatic signal in the fluctuations of the sea level and river run-off in the arctic ocean. extended abstracts of the international conference on polar processes and global climate, orcas island, usa, 3–6 november 1997, 184–186. peltier, w. r. 1999: global sea level rise and glacial isostatic adjustment. glob. planet. change 20, 93–123. pugh, d. t. 1987: tides, surges, and mean sea level. new york: john wiley and sons. rothrock, d. a., yu, y. & maykut, g. a. 1999: thinning of the arctic sea-ice cover. geophys. res. lett. 26, 3469–3472. shpaykher, a. o., fedorova, z. p. & yankina, z. s. 1972: mesgodovie kolebaniya gidrologicheskogo regima morey sibirskogo shel’fa, kak reaktsiya na atmosfernie protsessi. (interannual oscillations of the hydrological regime of the siberian shelf seas as a reaction to atmospheric processes.) aanii trudy 306, 5–17. leningrad: gidrometeoizdat. (in russian.) steele, m. & boyd, t. 1998: retreat of the cold halocline layer in the arctic ocean. j. geophys. res. 103(c5), 10,419–10,435. verduin, j., woodgate, r., fahrbach, e., meincke, j., oesterhus, s., shauer u. & tverberg, v. 1999: direct measurements of volume transport across fram strait. ices cm 1999/l:17. weingartner, t. j., danielson, s., sasaki, y., pavlov v. & kulakov, m. 1999: the siberian coastal current: a wind and buoyancy-forced arctic coastal current. j. geophys. res. 104(c12), 29,697–29,713. woodworth, p. l. 1993: a review of recent sea level research. oceanogr. mar. biol. annu. rev. 31, 87–109. woodworth, p. l., pugh, d. t., deronde, j. g., warrick, r. g. & hannah, j. (eds.) 1992: sea level changes: determination and effects. washington, d.c.: american geophysical union. fahrbach.indd 217fahrbach et al. 2001: polar research 20(2), 217–224 direct measurements of volume transports through fram strait eberhard fahrbach, jens meincke, svein østerhus, gerd rohardt, ursula schauer, vigdis tverberg & jennifer verduin heat and freshwater transports through fram strait are understood to have a significant influence on the hydrographic conditions in the arctic ocean and on water mass modifications in the nordic seas. to determine these transports and their variability reliable estimates of the volume transport through the strait are required. current meter moorings were deployed in fram strait from september 1997 to september 1999 in the framework of the eu mast iii variability of exchanges in the northern seas programme. the monthly mean velocity fields reveal marked velocity variations over seasonal and annual time scales, and the spatial structure of the northward flowing west spitsbergen current and the southward east greenland current with a maximum in spring and a minimum in summer. the volume transport obtained by averaging the monthly means over two years amounts to 9.5 ± 1.4 sv to the north and 11.1 ± 1.7 sv to the south (1 sv = 106 m3s-1). the west spitsbergen current has a strong barotropic and a weaker baroclinic component; in the east greenland current barotropic and baroclinic components are of similar magnitude. the net transport through the strait is 4.2 ± 2.3 sv to the south. the obtained northward and southward transports are significantly larger than earlier estimates in the literature; however, within its range of uncertainty the balance obtained from a two year average is consistent with earlier estimates. e. fahrbach, g. rohardt, u. schauer & j. verduin, alfred wegener institute for polar and marine research, box 12 01 61, d-27515 bremerhaven, germany; j. meincke, institute of marine research, university of hamburg, troplowitzstr. 7, d-22529 hamburg, germany; s. østerhus, bjerknes center, geophysical institute, university of bergen, allégaten 70, n-5007 bergen, norway; v. tverberg, norwegian polar institute, polar environmental centre, n-9296 tromsø, norway. fram strait is the only deep water passage to the arctic ocean. transports through fram strait therefore determine to a large extent the exchanges between the north atlantic and the arctic ocean and consequently influence water mass modifications in the world ocean. warm and saline atlantic waters flow through the strait into the arctic ocean where they are cooled by heat loss to the atmosphere and freshened mainly by river inflow and mixing with pacific waters, forming a relatively fresh shallow outflow of polar waters. formation of sea ice increases the salinity of the water column to an extent that saline deep water leaves the arctic ocean through fram strait to the south. this outflow affects the water mass modifications in the greenland, norwegian and iceland seas and feeds to some extent the overflow into the north atlantic. measuring these fluxes is a major requirement to understanding and quantifying the turnover rates within the large circulation cells of the arctic and the atlantic oceans. to this end, combined sea-going and modelling activities are being carried out within the european union mast iii programme variability of 218 direct measurements of volume transports through fram strait exchanges in the northern seas (veins), and flux measurements have been achieved by obtaining synoptic time series of water and property transports through the key passages. the field measurements in fram strait were carried out in cooperation with veins partners. the moorings were supplied by the alfred wegener institute, the norwegian polar institute and the university of hamburg. determining heat and salt-/freshwater transports through fram strait, and their variability, requires reliable estimates of the volume transport. past estimates of the transport through fram strait were achieved in two ways. they were either based on balance calculations for the arctic ocean mass, heat and/or dissolved substances using hydrographic measurements (e.g. östlund & hut 1984; rudels 1987; rudels & quadfasel 1991; schlichtholz & houssais 1999) or on direct observations of velocities, which are interpolated and extrapolated to obtain transports (aagaard et al. 1973; greisman 1976; hanzlick 1983; foldvik et al. 1988). the direct current measurements show a strong barotropic contribution of the west spitsbergen current. morison (1991) documented the seasonal variation of the barotropic flow (2 sv peak to peak) being of the same order of the magnitude as the mean transports. however, all these data sets cover only a part of the strait. notably, all transport estimates obtained from direct current observations result in larger values than those derived from balance estimates. with the warming of the atlantic layer in the arctic ocean which was observed during the ‘90s (e.g. quadfasel et al. 1991; carmack et al. 1995; zhang et al. 1998), the fluxes through fram strait attracted new interest. to distinguish between the effect of variations in the atmosphere—ocean fig 1. map of fram strait with the positions of the ctd section (line) and the moorings deployed during veins from september 1997 to september 1999 (dots). the location of the observation area is given in the insert, upper right. 219fahrbach et al. 2001: polar research 20(2), 217–224 interaction within the arctic ocean and variations which could be induced by changes in the water mass properties or the quantities of the flow through fram strait, appropriate measurements are needed. since a significant inflow into the arctic ocean occurs through the barents sea, final conclusions can only be drawn if both passages are taken into account. this paper concentrates on the direct current measurements in fram strait and describes the variability of the transports obtained by a twoyear-long record. the data from an extensive array of moored current meters allow us for the first time to derive strait-wide transports and to assess the validity of estimates obtained by different methods and at different time periods. data from september 1997 to september 1998, 14 moorings with 47 instruments were deployed in fram strait. one mooring was lost. during the second period, from september 1998 to september 1999, 14 current meter moorings were again deployed; all could be recovered (figs. 1, 2). since the recovery in 1999 occurred in early september, time series from september 1997 to august 1999 were used for analysis. the moored instruments covered the water column from 10 m above the seabed to approximately 60 m below the surface. the measurements extended from 6° 51’ w, at the eastern greenland shelf break, to 8° 40’ e, at the western shelf break off spitsbergen. to avoid as much as possible topographic variations in the strait, the transect was located at its eastern part along 78° 50’ n and at its western part along 79° n. during the first mooring period, from summer 1997 to 1998, 37 complete and 6 partial time series were obtained. for the second period, from summer 1998 to 1999, 44 instruments supplied full records. given the number of available instruments, the optimal coverage of the strait was achieved by a relatively narrow horizontal spacing of the moorings over the continental slopes, where strong horizontal gradients were expected, and a wider spacing in the interior. in the deep moorings one instrument was placed in the near surface layer, one in the centre of the atlantic water, one in the deep water and one in the near bottom layer. at the upper continental slopes only two or three current meters were needed to obtain a comparable resolution. for more details see reports by woodgate et al. (1998), fahrbach (1999) and schauer (2000). the uppermost current meters were falmouth scientific (fsi) 3-dimension acoustic current meters with temperature and pressure sensors. the other instruments were aanderaa rotor current meters with temperature sensors. both types of instruments were sent for maintenance and calibration before the deployment and after the recovery to assure the manufacturers’ specifications. two moorings in the east greenland current were equipped with upward-looking doppler profiling current meters from aanderaa. they recorded velocities in six levels between 50 m depth and the sea surface. the accuracy of the velocity data from the aanderaa rotor current meters amounts to 1 cm/s for a single measurement. threshold problems did not occur because the currents were always above the rotor thresholds. the accuracy of the fsi instruments amounts to 0.5 cm/s. the sample rates of both instrument types were set to 1 hour. temperature and salinity distributions were obtained with significantly higher spatial resolution by ctd (conductivity, temperature, depth) measurements during the deployment and recovery cruises (fig. 3). at this stage of the work, the temperature and salinity fields are only used to check the consistency of the current fields with the hydrographic features seen in the transect. the following analysis is based on spatially interpolated monthly mean velocity fields. the obtained values are influenced by the method to derive the fields. since we approached the method of our calculations stepwise, the numbers given here differ from those presented in earlier verfig. 2. vertical transect across fram strait with the location of the moored instruments deployed from september 1998 to september 1999. the deployment from september 1997 to september 1998 was instrumented similarly, but mooring f11-1 was lost. 220 direct measurements of volume transports through fram strait fig. 3. vertical transect of (a) the potential temperature in °c and (b) salinity in practical salinity units across fram strait measured with rv lance in september 1997. the numbers on top indicate the station numbers. fig. 4. vertical transect of the zonal current velocities through fram strait averaged over the time period from september 1997 to august 1999. currents to the north are positive, to the south negative. areas with currents higher than 5 cm/s are shaded. the numbers on top indicate the mooring numbers. (a) (b) 221fahrbach et al. 2001: polar research 20(2), 217–224 sions of this work. we summarize the applied procedure in some detail to make clear under which assumptions the values were obtained and what the expected uncertainties are. first, averages were calculated from the current velocity components over the full available record lengths for each point of measurement. to obtain fields of constant data coverage, gaps in the time series due to instrument failure were filled with the record length averages. then, monthly mean vertical profiles were obtained by linear interpolation between the instruments at each mooring in 2 m intervals. instead of then performing pure horizontal interpolation, we used information about the spatial structure of the fields from the ctd sections (fig. 3). in the ctd sections we identified layers (e.g. through temperature or salinity extrema or inflection points) and transferred the layers to the respective current meter profiles. each layer was split in grid cells. the vertical number of cells between two adjacent mooring positions was constant but the vertical extent varied with the layer thickness. then, vertical profiles of 1 km horizontal distance were interpolated between the centres of the corresponding grid cells. from the profiles data were extracted in constant vertical distance to obtain a rectangular grid of 2 m by 1 km. by this method, interpolation occurs nearly horizontally in the interior, whereas over the continental slopes the interpolation follows the bottom topography. it avoids the generation of artificial features which would not be justified by the data, conserves structures as boundary layers and permits the inclusion of a priori information from the temperature/ salinity transects by the definition of the layers. in the calculations and the displayed section only the meridional component of the current is used. due to the position of the mooring transect, the transport calculations refer to 78° 50’ n in the east and 79° 00’ n in the west. the recirculation within the strait yields a significant zonal transport between 78° 50’ n in the east and 79° 00’ n. this transport between the eastern and western part of the array is estimated from the zonal current components at moorings f8 and f9. results the velocity field averaged over two years from september 1997 to august 1999 reflects the well known current system in fram strait (fig. 4). the northward flowing west spitsbergen current obtains its maximum speed of 24 cm/s in the near bottom layer of the core over the upper continental slope. the southward flowing east greenland current core with a maximum velocity of 9 cm/s is located in the upper 200 m of the water column over the deeper part of the continental slope (fig. 4). both currents are confined to bands of about 100 km width over the eastern and western slopes. they are separated by an area of 100 km width where zonal, mostly westward, currents with a weak southward component prevail. the water mass properties of the upper and intermediate layers indicate that this area with meridional velocities of about 1 cm/s is governed by recirculating water of atlantic origin (fig. 3). the west spitsbergen current has a strong barotropic component (determined as the vertical average of the velocity profile) of up to 20 cm/s, discernible by the nearly vertical isolines of the current velocity (fig. 4). the barotropic component of the east greenland current is only less than 5 cm/s. the baroclinic components of both the west spitsbergen and the east greenland currents are of a similar magnitude—about 5 cm/s. in the following discussion of volume transports we refer for simplicity to the complete northward transport as west spitsbergen current and to the complete southward transport as east greenland current, despite the separation of some surface or subsurface current bands from the main currents by areas flowing in the opposite direction (fig. 4). monthly mean northward and southward transports were calculated by integrating the interpolated monthly mean velocities fields. the average volume transports over two years were calculated by averaging the monthly mean transports to 9.5 ± 1.4 sv to the north at 78° 50’ n and 11.1 ± 1.7 sv to the south at 79° 00’ n. the zonal transport between 78° 50’ n and 79° 00’ n obtained from moorings f8 and f9 amounts to 2.6 ± 0.1 sv to the west. this flow has to be added to the southward transport to obtain a net transport across a constant latitude of 78° 50’ n or subtracted from the northward transport to refer to 79° 00’ n. in the following, we will use transports referred to 78° 50’ n. the obtained monthly mean volume transports (fig. 5) through the strait are subject to intensive fluctuations with time scales from a few months to the record length. the west spitsbergen current has a strong annual cycle with maximum transport in winter (february) of 20 sv and a 222 direct measurements of volume transports through fram strait minimum of 5 sv in summer (august). this cycle occurs consistently in both years. the fluctuations on monthly time scales are on the order of 2 sv. the variability of the east greenland current is less clear. whereas in the first year (summer 1997 to summer 1998), a strong maximum occurs in winter, simultaneously with the one in the west spitsbergen current, in the following year (summer 1998 to summer 1999) the east greenland current reaches a minimum during the occurrence of the maximum in the west spitsbergen current. in spring 1998 strong northward and southward transports but weak net transports indicate intensive recirculation in the strait. in spring 1999, the net flow reaches a peak value to the north which does not recirculate within the strait. in the east greenland current semi-annual fluctuations are more prominent. in both years transport maxima between 19 and 24 sv occur in autumn (december) and spring (april to june). the persistence of the extrema in the time and intensity suggests a stable mode of variability. to investigate the stability of the transport estimates cumulative averages were calculated for the northward and southward transports, i.e. the averaging period was increased in monthly steps and the results of an average over 1, 2, 3 etc. months are displayed as time series (fig. 6). the obtained mean transports increase by about 4 sv during the first seven months and then remain rather constant. a second step occurs in the transport of the west spitsbergen current at an average period of 15 months. this development towards a stable mean reflects the dominant effect of the annual cycle since the time series start in summer during a period of weak transports. the net southward transport decreases with increasing average period to 4.2 ± 2.3 sv as the average over two years. the differences of the monthly averages between northward and southward transports between 0.3 and 10.9 sv seem unrealistic because an outflow of this magnitude over a month would lead to a noticeable sea level depression in the arctic ocean. however, nøst et al. (2000) report an inflow of similar intensity, which might compensate for this outflow, south of spitsbergen in february 1999. it remains to be investigated if a flow like this would be consistent with the water mass property distribution. however, we cannot fully rule out that the monthly averages might still be affected by aliasing due to meso-scale perturbations. uncertainties the transport estimates are subject to uncertainties in the measured current velocities and the fig. 5. monthly averages of the volume transport through fram strait determined from the current meter array moored from september 1997 to august 1999. the errors are given as shaded areas. the southward transport is referred to 78° 50’ n by adding the recirculation between moorings f8 and f9. fig. 6. cumulative averages of the monthly volume transports through fram strait determined from the current meter array moored from september 1997 to august 1999. errors are shown as shaded areas. the southward transport is referred to 78° 50’ n by adding the recirculation between moorings f8 and f9. 223fahrbach et al. 2001: polar research 20(2), 217–224 interpolation method which includes rounding errors. the current velocity measurements are affected by instrumental errors and time variability. random instrumental errors can be neglected since the monthly averages were calculated from a large number of individual hourly samples. systematic errors were avoided by calibration. the variability of the daily values after having removed tides indicates that meso-scale eddies (fluctuations with time scales of several days which are not correlated between adjacent moorings) would alias the estimates of daily transport time series. therefore, monthly velocity averages were calculated to eliminate the effect of mesoscale perturbations before the interpolation. the uncertainty of the monthly velocity means due to the eddy noise was estimated as the error of the mean. the number of independent samples was calculated from the integral time scale for each month-long time series. the uncertainty due to interpolation depends on the structure of the fields. since the eddy field is eliminated by time averaging, the interpolation error has to describe to what extent the interpolated large-scale field represents the real largescale field between the moorings. with an average distance of 24 km between the moorings a monotonic structure of the large scale field between them is likely. the potential error then increases with velocity difference which is spanned by the interpolation. therefore, the interpolation error within the area of influence of each instrument (halfway to the adjacent instruments or the distance to the boundary) was estimated as the mean of the velocity differences to the adjacent points. the obtained errors of the monthly mean velocities and the interpolation were weighted by the area of influence of each instrument and applied by gaussian error propagation on the northward, southward and the net transport calculations (figs. 6, 7). the errors of annual and biannual means were obtained similarly from year-long and twoyear-long time series (table 1). we calculated annual or biannual averages on the basis of monthly transport estimates to capture the transport variability. due to the nonlinearity of the transport of a current with variable spatial extent, annual mean northward and southward transports calculated on the basis of annual mean velocity fields are different from those obtained as averages of monthly mean transports. both are given in table 1. conclusions the obtained volume transports are all significantly larger than earlier estimates given in the literature. the transport in the west spitsbergen current of 9.5 ± 1.4 sv is larger than hanzlick’s (1983) the estimate of 5.6 sv. even larger is the discrepancy to values obtained from hydrographic data estimated through inverse methods by rudels (1987) and schlichtholz & houssais (1999) of 3.0 and 1.1 sv, respectively. despite the inverse approach, which aims to overcome the weakness of calculations based on the baroclinic currents and an arbitrary reference level, these authors largely underestimate the barotropic contribution. our estimate of the transport in the east greenland current of 13.7 ± 1.7 sv is larger than schlichtholz & houssais’s of 6.2 sv and rudels’s of 4.1 sv. the estimate of foldvik et al. (1988) of 3 sv, based on current meter observations, includes only the upper 700 m and a much smaller horizontal extent than our measurements and cannot be easily compared. besides methodological reasons, the larger transport in comparison to earlier estimates can be due to the northward shift of the recirculation in the greenland sea. the higher temperatures observed in fram strait from 1997 to 1999 in comparison to the ‘80s support the northward shift. further analysis of the data has to show mean volume transport (106 m3s-1) transport southward northward differrecircufrom period at 79° n at 78° 50’ n ence lation net 09/97– 11.6 9.0 2.6 s 2.8 w 5.4 s 08/98 ± 2.5 ± 0.9 ± 3.1 ± 0.2 ± 3.2 09/98– 10.7 10.1 0.6 s 2.4 w 3.0 s 08/99 ± 2.4 ± 2.2 ± 3.2 ± 0.2 ± 3.3 09/97– 11.1 9.5 1.6 s 2.6 w 4.2 s 08/99 ± 1.7 ± 1.4 ± 2.2 ± 0.1 ± 2.3 09/97– 9.8 6.9 2.9 s 2.8 w 5.7 s 08/98 ± 2.2 ± 1.9 ± 2.9 ± 0.1 ± 2.9 09/98– 8.8 8.1 0.7 s 2.4 w 3.1 s 08/99 ± 2.2 ± 2.1 ± 3.0 ± 0.1 ± 3.0 09/97– 8.9 7.2 1.7 s 2.6 w 4.3 s 08/99 ± 1.6 ± 1.3 ± 2.0 ± 0.1 ± 2.0 table 1. volume transports for the two years of observations,from september 1997 to august 1999, calculated from the monthly transports and from annual and biannual means of the velocities. the calculated uncertainties are described in the text. monthly mean transports annual mean velocities 224 direct measurements of volume transports through fram strait if a northward shift of the recirculation affects the heat flow through the strait. the most serious restriction of the comparison of meridional transports is the large meridional variation due to the recirculation. an average decrease of the northward transport in the east or the increase of the southward transport in the west by 2.6 sv over a distance of 10 nm, which is normally the station distance, requires comparisons at the same exact location. this holds not only for comparisons between different observations but also for the comparisons with model results which are normally not available on gridpoints corresponding to the location of the observed section. however, since the net transport is not affected by the recirculation if it is properly resolved, it can be used for comparison. the aim of the project was to design an optimal array of moored instruments, suitable to be maintained for longer time periods. working out the relation of transport fluctuations to variations in the sea level elevation or bottom pressure differences might permit the use of fewer moorings after the establishment of an appropriate calibration data set. under the assumption of the geostrophic equilibrium, the bottom pressure difference along the transect corresponds to the barotropic current perpendicular to it. since the baroclinic current seems to be small in comparison to the barotropic currents, variations of the sea level elevation or bottom pressure differences might be used to derive transport fluctuations after appropriate corrections for the baroclinic component. the hypothetical differences of the sea level elevation across the west spitsbergen current derived from the barotropic currents measured with the moored instruments vary from 15 cm in february 1999 to 5 cm in august 1999. consequently, the expected sea level or bottom pressure variations are in the range to be measured. however, the transition from northward to southward flow, i.e. the zonal limit between the two current systems, was displaced by more than 250 km westwards during winter, necessitating the measurement of the horizontal pressure profile to enable us to estimate transports. we conclude that transport estimates of atlantic water through fram strait towards the arctic ocean and, consequently, of a reliable heat transport can only be obtained by direct current measurements which sufficiently resolve the recirculation. therefore, further time series measurements with moored instruments are required. acknowledgements.—we are grateful to matthias monsees, ekkehard schütt and andreas wisotzki who participated in the work at sea, the data processing and provided drawings. we appreciate the valuable contribution of rebecca a. woodgate to advance the project during her stay in bremerhaven and the later analysis by intensive and fruitful discussions. a significant part of the work was carried out under the european union mast iii veins programme, contract number mas3-ct96-0070. references aagaard, k., darnall, c. & greisman, p. 1973: year-long current measurements in the greenland–spitsbergen passage. deep-sea res. 20, 743–746. carmack, e. c., macdonald, r. w., perkin, r. g., mclaughlin, f. a. & pearson, r. j. 1995: evidence for warming of atlantic water in the southern canadian basin of the arctic ocean: results from the larsen-93 expedition . geophys. res. lett. 22, 1061–1064. fahrbach, e. (ed.) 1999: the expedition arktis xiv/2 of the research vessel polarstern in 1998. berichte zur polarforschung 326, 1–114. foldvik, a., aagaard, k. & tørresen, t. 1988: on the velocity field of the east greenland current. deep-sea res. 35, 1335–1354. greisman, p. e. 1976: current measurements in the eastern greenland sea. phd thesis, university of washington. hanzlick, d. j. 1983: the west spitsbergen current, transport, forcing and variability. phd thesis, university of washington. morison, j. h. 1991: seasonal variations in the west spitsbergen current estimated from bottom pressure measurements. j. geophys. res. 96(c10), 18,381–18,395. nøst o. a. 2000: adcp and ctd measurements on np veins cruises across the barents sea opening. in h. loeng (ed.): summary report to veins meeting in hamburg, 19–21 january 2000, workpackage 1.2: northeastern boundaries. östlund h. g. & hut, g. 1984: arctic ocean water mass balance from isotope data. j. geophys. res. 89(c4), 6373–6381. quadfasel, d., sy, a., wells, d. & tunik, a. 1991: warming in the arctic. nature 350, 385. rudels, b. 1987: on the mass balance of the polar ocean, with special emphasis on the fram strait. nor. polarinst. skr. 188. olso: norwegian polar institute. rudels, b. & quadfasel, d. 1991: convection and deep water formation in the arctic ocean—greenland sea system. j. mar. syst. 2, 435–450. schauer, u. (ed.) 2000: die expedition arktis xv/3 des forschungsschiffes polarstern 1999. berichte zur polarforschung 350. schlichtholz, p. &. houssais, m.-n. 1999: an inverse modelling study in fram strait. part i: dynamics and circulation. deep-sea res. ii 46, 1083–1135. woodgate, r., schauer, u. & fahrbach, e. 1998: moored current meters in the fram strait at 79° n: preliminary results with special emphasis on the west spitsbergen current. ber. fachber. phys. 91, 1–25. zhang, j., rothrock, d. a. & steele, m. 1998: warming of the arctic ocean by strengthened atlantic inflow: model results. geophys. res. lett. 25, 1745–1748. 22_2_405 22_2_406 22_2_407 22_2_408 22_2_409 rb-sr whole rock and u-pb zircon datings of the granitic gabbroic rocks from the skglfjellet subgroup, southwest spitsbergen yu. a. balasov, j. j. peucat, a. m. teben’kov, y. ohta, a. n. larionov, a. n. sirotkln and m. bjornerud balasov, yu. a,, peucat, j. j., teben’kov, a. m., ohta, y., larionov, a. n., sirotkin, a. n. & bjornerud, m. 1996: rb-sr whole rock and u-pb zircon datings of the granitic-gabbroic rocks from the skllfjellet subgroup, southwest spitsbergen. potar research 15(2), 167-181. recent remapping and new age determinations has shed light on the understanding of precambrian rocks northwest of hornsund, southwest spitsbergen. the skllfjellet subgroup has been regarded as the eastern equivalent of the vimsodden subgroup, and both of these occur within the precambrian eimfjellet group of southwest spitsbergen. although the eimfjellet group is considered to be older than the oldest unconformity in the area, the age of the rocks has not been known. the granitic-gabbroic rocks in the skllfjellet subgroup have been considered to be the products of granitisation for many years, but recent observations show that they are exotic blocks incorporated into the basic eruptive rocks which are the main constituents of the subgroup. these plutonic rocks have a wide range of compositions, from syenite via granite to gabbroic cumulates, which suggests the existence of a well-differentiated plutonic body at depth. u-pb zircon and pb evaporation datings yielded magmatic ages of ca. 1,100 to 1,200 ma, and a conformable age has been obtained by rb-sr whole rock dating. detrital zircons from the micaceous schists of the isbj~rnhamna group, which underlies the skllfjellet subgroup, show a poorly defined discordia with an upper intercept age of ca. 2,200 ma and a lower intercept age of ca. 360 ma. these dating results define the magmatic age of the granitic-gabbroic rocks as late mesoproterozoic, early grenvillian. this age is in broad agreement with that of the metavolcanic rock clasts of the pyttholmen meta-pyroclastic conglomeratic unit at vimsodden, which is considered to be the westernmost occurrence of the skllfjellet subgroup. a rb-sr whole rock age determination of the shaly phyllites from the deilegga group was performed in order to place constraints on the age of younger precambrian event; however, no good isochron was obtained. yu. a. balasov and a . n. larionov, laboratory of isotope geochemistry, geological institute of kola science centre, russian academy of sciences, ul. fersman 14, 184200 apatity, russia; j . j . peucat, laboraioire de gtochimie isotopique et de geochronologie, geosciences rennes, f-35042 rennes ceder, france; a . m. teben’kov and a . n. sirotkin, polar marine geologic expedition, ul pobedy 24, 189510 lomonosov, st. petersburg, russia; y. ohta, norsk polarinsiiiutt, p.o. box 5072 majorstua, n-0301 oslo, norway; m. bjornerud, geology department, lawrence university, appleton, wisconsin 54912, u s a . geological outline a precambrian granite-gabbro complex has long been known to the northwest of hornsund, southwest spitsbergen (hoe1 1918; orvin 1940; birkenmajer & narebski 1960; smulikowski 1965 and 1968, teben’kov 1983; birkenmajer 1992) (figs. 1a & 1b). precambrian rocks in this area have been divided into four groups and two precambrian tectonic events have been proposed by birkenmajer (e.g. 1975 and 1992) (table 1 and fig. 1a). the skdlfjellet subgroup has been considered to be an eastern lithofacies of the eimfjellet group, contemporaneous with the vimsodden subgroup to the west (birkenmajer 1992). the skdlfjellet subgroup consists mainly of meta eruptive mafic rocks, with felsic rocks being in the minority. the lower part of the eruptive basic sequence contains granitic and gabbroic blocks as much as tens of metres in length. these coarse grained rocks have been considered the products of granitisation by most previous authors (orvin 1940; birkenmajer & narebski 1960; smulikows ki 1968). these blocks are confined within three layers of metabasic, eruptive rocks (fig. 1b). the lowest layer includes mainly granitic-syenitic blocks, the second tonalitic blocks, and the third mostly gabbroic blocks, while some amounts of blocks of 168 yu. a . balasov et al. fig. 1 . geological maps. a northwestern hornsund, with an inset location map, modified from ohta & dallmann 1994 (updated version 1996). birkenmajer 1993 and 1994 have not been incorporated because the authors differ with his interpretation. place names: g = gangpasset, p = polish station at isbjarnhamna, rv = revdalen, s = skilfjellet, v = vimsodden. b, c and d denote localities of metasediment samples of the deilegga group. b: detailed map around gangpasset. 1 signifies the lowest block bearing layer, mainly with granite-syenite blocks; 2, second block-bearing layer, mainly with tonalitic blocks, 3, third block bearing layer, mainly with gabbroic blocks. the analysed samples were collected in the east of gangpasset. place names: em = eimfjellet; rv = revdalen; tb = torbjarnsenfjellet; tr = trulsenfjellet. these different lithologies occur mixed in all three layers. the blocks commonly have a subangular outline (fig. 3a), show a very sharp boundary with the surrounding metaeruptive rocks, and are occasionally cut by thin veins of the latter (fig. 3c). the blocks have holocrystalline textures and grain sizes that are distinctly coarser than the surrounding rocks, without gradational transition in grain size from block to host rock. the internal structures of the gabbroic blocks in the third block-bearing layer, represented by plagioclaseand mafic-rich compositional layers and shear planes (fig. 3d), are variously rotated with respect to the structures of the surrounding rocks (fig. 3b). some blocks are almost anortho sitic in composition, including thin cumulative mafic-rich layers which contain distinct seams of ilmenite concentration. plagioclase and horn blende in the gabbroic blocks show cumulate textures. the tonalitic rocks from the second block-bearing layer have coarse-grained, equigra nular hypidiomorphic textures. the surrounding metaeruptive rocks are most l y dense, schistose amphibolites, having actino lite-epidote-bearing assemblages with rare relict hornblende and dusty plagioclase grains. clea rb-sr whole rock and u-pb zircon datings of the granitic-gabbroic rocks 169 birkenmajer (1992) group formation : !? gishamna s sofiebogen *h&rpynten !? a 0 a3 slyngfjellet &(tomlllm event) n present paper s of werenskiodbreen n of werenskiodbreen kvisla unit ghhamna (unexposed) hgferpynten fig. 2 . lithostratigraphy of the precambrian rocks north of hornsund. second and third columns from the left: birkenmajer 1993 and 1994 are not incorporated because the authors differ with his interpretation. fourth and fifth columns: modified from ohta & dallmann (1994, up-dated version 1996). *u a p 22 2 8 b fig. 3. photographs showing the occurrences of the granitic-gabbroic blocks in the meta-eruptive rocks of the skilfjellet subgroup. scales: hammer shaft ca. 30 cm, lense-cap ca. 4 cm across. a sharp contact between granitic block and meta-eruptive rock with plagioclase phenocrysts and amygdaloidal texture. b rotated granitic blocks in the meta-eruptive rocks, with sheared margins. c a granitic block with partially sheared margin, cut by a vein of eruptive rock. d: cumulate compositional layers within a gabbroic block. 1 oeilegga s ( w e r e n s k i o l d i r n event)- skilfjellet (unexposed) subgroup vimsodden skalfjellet subgroup subgroup gulliksen steinvi kskadet gulliksenfjellet revdalen revd alen lsblnrnhamna ariekammen ariikammen skoddefjellet skoddefjellet eirnfjellet = feldsparthic quartzite e 170 yu. a. balasov et al. vages are locally strong, and thin shear planes occur along the boundaries and inside the blocks. less schistose parts of the metaeruptive rocks locally contain small white plagioclase crystals with prismatic outlines and granulated interiors similar to a protoclastic texture, indicating that they are a primary phenocryst phase. round white spots consisting of calcite and quartz suggest primary amygdaloidal textures. the occurrences and lithologies of the blocks and relict-volcanic textures of the surrounding rocks can not be explained by granitisation, and the blocks are considered to be exotic inclusions from underlying plutonic bodies, incorporated into the eruptive rocks. czerny et al. (1993) made a similar interpretation. the inferred plutonic body seems to have been strongly differentiated, ranging in composition from gabbro-anorthosite cumulates to granitic-syenitic rocks, and was mostly consolidated when the eruptive rocks were extruded. thus, a sequential magmatic activity, including the formation of both eruptive and plutonic rocks, is inferred from the igenous rocks of the skdlfjellet subgroup. these observations suggest that these rocks are all of similar age, with the plutonic rocks possibly being older. the eruptive rock succession of the skdlfjellet subgroup is underlain by two-mica, locally garnet-bearing, schists of the isbjornhamna group. this group has been divided into three formations by birkenmajer (1959, 1992; fig. 2), the middle of which is calcareous and includes some marble layers. direct contacts between the skllfjellet sub group and the isbj0rnhamna group have been observed at more than ten localities and all are conformable. a 3-15 m thick, feldspathic quart zite layer overlies the biotite schists of the revdalen formation, the upper division of the isbjornhamna group, with a sharp lithological change, but without any structural discontinuity. large scale fold structures including the two successions are also conformable. the schists of the isbjornhamna group contain metamorphic mineral assemblages of garnet muscovite with or without graphite, garnet biotite-muscovite and garnet-muscovite-epidote calcite, all with plagioclase (oligoclase) and quartz. the secondary assemblages include albite, quartz, sericite, chlorite and later calcite. acces sory minerals are tourmaline, zircon, titanite, rutile and pyrite. some schists contain chloritoid, kyanite and staurolite, indicating metamorphic conditions of middle amphibolite facies of an intermediate-pressure series. these conditions do not provide sufficiently high conditions for granitisation as proposed by previous authors. birkenmajer (1975, 1992) placed the eimfjel let and isbjornhamna groups earlier than his werenskioldian event (fig. 2). an angular unconformity has been well established at the base of the sofiebogen group, cutting the folded deilegga group in the northern werenskioldbreen area (fig. 1a). this tectonic break has been named the torellian event (fig. 2). the age relationship between the geological units to the north and the south of werenskioldbreen has not been established because of lack of exposure. the pittholmen meta-pyroclastic-conglomerate unit, from which previous u-pb zircon ages were reported by balasov et al. (1995), is considered the westernmost occurrence of the upper skllfjel let subgroup based on new observations (ohta & dallmann 1994), and is separated from the vimsodden subgroup of birkenmajer (1992). a new name, the kvisla unit, has been introduced for the former vimsodden subgroup without pittholmen unit (ohta & dallmann 1994, up dated version 1996). the kvisla unit roughly corresponds to the kvisla member of the notting hambukta formation plus elveflya formation of birkenmajer (1993,1994) and the pyttholmen unit includes the pyttholmen and kvislodden members of the same author. the kvisla unit contains distinct tilloids in front of werenskioldbreen and in fig. 2 it is therefore placed in the late vendian. the boundary between the pittholmen unit and the kvisla unit is a fault along the southern coast of vimsodden, which accompanies many small sheared zones with sulphide mineralisation. previous dating the ages previously reported for the isbjomham na group are two cambrian war apparent ages for biotite from the schists (gayer et al. 1966). u pb zircon ages of the quartz porphyry and rhyolite clasts from the pyttholmen meta-pyroclastic conglomerate unit of the vimsodden subgroup of birkenmajer (1992), were reported in balasov et al. (1995). they indicate a magmatic age of ca. 1.2 ga, a metamorphic age of ca. 930 ma and an inherited zircon age of ca. 2.5 ga. the rb-sr whole rock, metamorphic age of the isbjornhamna rb-sr whole rock and u-pb zircon datings of the granitic-gabbroic rocks 171 fig. 4. classification of the dated samples from the skilfjellet subgroup, after debon & le fort (1983). symbols: open circle, blocks from the second block-bearing layer; filled circles, blocks from the third block-bearing layer. the same symboles are used in figs. 4 to 9. schists was also reported to be ca. 930 ma (gavrilenko et al. 1993). description of the samples two sample sets, tonalitic rocks (sample series 5-) and gabbroic rocks (series 6-) of the skllfjellet subgroup, one set of schists from the isbjom hamna group (series 4-), and three shaly phyllite samples (from localities b, c and d, fig. 1a) of the deilegga group were collected in 1989. age determinations for these specimens are reported in this paper. petrography sample series 5and 6were collected from the second and third block-bearing layers, respec tively, of the lower part of the skhlfjellet subgroup, near the eastern part of gangpasset (fig. 1b). the samples from the third block bearing layer are called gabbroic rocks in the field and marked by the same symbol in the figures, but they include a tonalite and a syenite. samples 5-1 and -4 are fine-grained, schistose cataclastic tonalitic rock (fig. 4), consisting of 50% quartz, 35% plagioclase (albite) and 5% biotite. accessories, which constitute up to 10% of the rock by volume, are orthite, zircon, apatite, pyrite and sphene, and secondary epidote-zoisite, p=k-fna+cal chlorite and carbonates. sample 5-2 is a tonalite in chemical composition and has a similar texture, but is apparently granodioritic in handspecimen, having less quartz (ca. 30%) and more biotite (ca. 20%). a few grains of hornblende are found, and apatite and opaque grains are accessories. sec ondary chlorite represents as much as 15-20% of the rock and some zoisite grains occur. sample 5 3 is a tonalite and has a similar texture and modal composition to 5-1, but secondary chlorite and carbonates are absent. octahedral grains of brown-green spinel, up to 0.2 mm in size, are found as an accessory phase. sample 6-1 is a rare tonalitic block in the third block-bearing layer, which is dominated by gabbroic blocks. the rock is coarse-grained and has 40-60% plagioclase (albite), 2&25% quartz and 10-20% hornblende. secondary epidote zoisite constitutes ca. lo%, and accessories are biotite, chlorite, zircon, apatite and opaques. the rock is massive and has a prismatic-mosaic texture. samples 6-3, 6-4 and 6-5 are coarse grained, massive hornblende gabbros with or without biotite, having prismatic mosaic-textures. major consituents are albitised plagioclase (as much as 60%), amphiboles (light green hornble nde and actinolite, 20-30%) and biotite (up to 10%). secondary minerals including chlorite, epidote-zoisite and carbonates make up the remaining 10-20%. accessories are rutile, sphene, pyrite, ilmenite and zircon. 172 yu. a. balasov et al. ,' 6-3 1 oj v v v a 10 20 30 40 fig. 5. f m diagram. soli curve indicates the tholeiite calcalkaline division (irvine & baragar 1971); broken curve, common calcalkalic rock field (ringwood 1974). sample 6-2 is a porphyroblastic rock rarely found in the third, gabbro block dominating layer. k-feldspar megacrysts, ca. 60 modal percent and up to 7 mm in size, replaced the matrix of albitised plagioclase (20%), hornblende (10%) and biotite (lo-ls%). plagioclase is also partly table 1 . chemical compositions of the granitic (nos. 5 ) and gabbroic (nos. 6-) rocks of the sk2fjellet subgroup. sample nos. 5are from the second block-bearing layer and samples nos. 6are from the third bfock-bearing layer. blank boxes mean not determined. 5-1 5-2 5-3 5 -4 6-1 6-2 6-3 6-4 6-5 73.78 0.35 14.52 0.65 0.93 0.06 0.47 1.36 4.42 1.44 0.01 0.00 0.07 0.56 63.10 0.71 15.23 1.44 3.81 0.05 4.65 2.15 4.30 0.98 0.11 0.05 0.22 2.94 71.13 0.22 17.68 0.43 1.15 0.05 0.44 1.09 6.51 0.24 0.08 0.04 0.05 0.60 69.91 0.54 14.34 1.25 2.44 0.06 1.55 4.23 3.26 0.98 0.02 0.08 0.05 0.70 65.22 0.78 17.30 1.95 1.36 0.05 1.22 5.73 4.82 0.77 0.07 0.16 0.05 0.86 61.29 0.74 18.85 1.60 2.66 0.07 0.92 2.86 5.29 6.01 0.13 0.08 0.05 0.62 51.52 0.73 21.38 2.37 3.95 0.10 3.60 10.34 4.07 0.85 0.01 0.10 0.05 1.36 50.72 0.78 18.30 2.11 6.03 0.14 5.11 8.79 3.83 0.23 0.05 0.16 0.05 1.78 ~ 52.63 0.92 20.07 2.30 4.38 0.10 4.40 9.41 4.47 0.68 0.03 0.16 0.05 1.50 total 98.62 99.74 99.71 99.41 100.34 101.17 100.43 98.08 100.70 rb sr ba zr v zn c o nb y ni cr c u 38 15 86 135 170 100 281 1230 7 10 12 35 30 97 133 94 91 8 25 190 20 10 8 ~ 13 191 200 372 20 24 203 124 10 40 20 20 14 268 385 280 250 363 435 20 110 24 15 10 32 18 32 58 10 9 120 110 9 10 63 174 2910 452 47 56 41 10 50 10 14 494 190 36 140 36 25 8 8 40 120 20 39 i5 532 477 620 190 68 88 140 160 36 30 30 15 12 14 13 40 30 110 120 15 10 rb-sr whole rock and u-pb zircon datings of the granitic-gabbroic rocks 173 6 5 s t 4 8 3 2 1 fig. 6. log,, caohotal alkalis vs. sioz diagram. calc-alkaline andesite field from brown (1982). -0.1 -0.6 0 6-2 -1.1 i i l 50 55 60 65 70 75 si02 wt% replaced by quartz. secondary chlorite and epidote-zoisite are common? and apatite and zircon are the accessories. the samples from the isbjarnhamna group are various garnet-mica schists. sample 4-1 is a fine grained schist with garnet porphyroblasts. it consists of 15% garnet, 5 7 % plagioclase, 10-15% quartz, 20-25% muscovite and 3540% chloritoid. the chloritoid grains contain streaky graphite, and kyanite occurs between chloritoid grains. the schistosity is marked by muscovite flakes. accessories are tourmaline, zircon, orthite, apatite and opaques, and secondary chlorite and sericite occur in small amounts. samples 4-2 to 4 5 are medium-grained, garnet-two-mica schists consisting of 15-30% quartz, 10-20% plagio clase, 5-20% muscovite, 5 2 0 % biotite and 5-10% garnet. accessories are the same as in 4 1 with the addition of sphene (up to 2-3%). secondary chlorite represents ca. 2-10%. samples 4-3, 4-4 and 4-5 contain secondary epidote-zoisite and carbonates. all three metasediment samples from the deilegga group came from sites close to the deilegga/slyngfjellet unconformity (fig. 1a) and are fine-grained, phyllitic rocks derived from calcareous and shaly protoliths. mineral assem blages in all samples indicate low-grade, sub greenschist facies metamorphism. samples b and c are from the western limb of a major n-s anticline. the former sample is a calcareous shale containing white mica, quartz, dolomite and opaques, while the latter is more pelitic and lacks dolomite. sample d, collected from the eastern limb, is a pure dolomitic marble. all three samples include carbonate veins, but these are excluded from the materials used for the rb-sr analyses. petrochemistry major and trace elements of the dated rocks were analysed by the x-ray fluorescence method on the krf-18 device at the sevzap geologija laboratory in st. petersburg (table 1). samples 6-3,6-4 and 6-5 are gabbros, while 5 1, -2, -3, -4 and 6-1 are tonalites and 6-2 is a syenite (fig. 4; debon & le fort 1983). in the streckeisen & maitre (1979) classification, 5-1 is a granodiorite, while the rest are in the same categories as shown in fig. 4. the rocks are classified as granites to tonalites and gabbros in the r 2 vs. r1 diagram of la roche et al. (1980). sample 6-2 has a syenitic composition in all three classifications mentioned above and is similar in appearance to the blocks in the lowest block bearing layer, which have not been analysed in 5 4 ,64a 6-5 , 1 2 3 4 5 6 7 nan0 wt% fig. 7. kzo vs. nato diagram. the i-type and s-type granite fields are from chappell & white (1974). 174 yu. a . balasov et al. 0.8 0.9 i .o 1 .i 1.2 1.3 1.4 a1203/cao+nazo+k20 fig. 8. a1203-saturation diagram. classification after maniar & piccoli (1989): cag, continental arc granites; ccg, continetal collision granites; ceug, continetal epeirogenic uplift granites; iag, island arc granites; op, plagiogranites; pog, post-orogenic granites; rrg, rift-related granites. this study. the high k 2 0 content of this rock reflects the k-feldspar replacement as mentioned in the petrographic description of the samples. most samples are in the calcalkaline field on the afm diagram (fig. 5), and plot within or near the field of modern calcalkaline andesite-dacites of brown (1982) (fig. 6) . the nazo vs. k 2 0 diagram (fig. 7; chappell & white 1974) shows that most samples, except for 5-4 and 6-2, are in the field of i-type granite. the tonalitic rocks are of the trondhjemite tonalite series in the normative or-ab-an dia gram of barker (1979), and have slightly higher or contents than oceanic plagiogranite (maniar & piccoli 1989). sand's diagram of maniar & piccoli (1989) shows that the majority of tonalitic rocks are peraluminous, and all gabbros plot in the metaluminous field, owing to the existence of hornblende (fig. 8). no tectonic setting can be estimated from this figure. the high al contents in the tonalitic rocks can be explained by the existence of chlorite and epidote which were formed during later metamorphism. this infer ence is consistent with the fact that six of the nine analysed samples are projected outside the igneous spectrum on the total alkalis vs. 100 . a wpg 5 2 8 05-3 100 r 10 syn-colg 100 k20 rb ba nb zr y fig. 9. trace element ratios of the samples with more than s i 0 2 = 60%. a: nb vs. y diagram after pearce et al. (1984). vag = volcanic arc granite; syn-colg, syn collision granite; wf'g =within plate granite; org = ocean ridge granite. b: spider diagram of the trace elements, normalised by ocean ridge granites (org). rb-sr whole rock and u p b zircon datings of the granitic-gabbroic rocks 175 i k,o/total alkali diagram of hughes (1973), suggesting metamorphic modifications. trace element ratios have been used to determine the tectonic settings of the rocks (pearce et al. 1984). all tonalitic rocks plot in the wpg field on the nb vs. y diagram (fig. 9a). a spider diagram (fig. 9b), normalised to org, shows several times higher kzo, rb, ba, and nb than org. isotopic datings three methods of isotopic age determination have been applied in this study: (1) the classical u-pb zircon dissolution method of krogh (1973), for sample series of 4and 6-, with an imperfect analysis of sample 5-2; (2) the single-grain pb evaporation method of kober (1986) on zircon grains from samples 5-3, 6-1 and 6-2; and (3) rb sr whole rocks dating on sample series 5and 6-. three samples of shaly phyllites from the deilegga group were commercially analysed by this method in u.s.a. analytical methods the u-pb zircon analysis was performed at the isotope geochemistry institute of kola science centre, apatity, russia, using an mi 1201-t mass-spectrometer (balasov et al. 1995). the lead and uranium blanks are less than 0.5 ng and 0.05 ng, respectively. the analytical errors of the isotope composition measurements of pb and of the isotope dilution analyses of pb and u, using 208pb and 235u spike, are shown in table 2. the analytical procedures were assessed by running the igfm-87 and nbs-981 standards, and the calculations have been done using the programs of ludwig (1991a, b). the single grain zircon evaporation analyses were performed at the isotope laboratory of rennes university, france, following the proce dure proposed by kober (1986), using a finnigan mat 262 mass-spectrometer, except for sample 6-2 which was analysed by a cameca tsm 206 mass spectrometer. correction for mass fractiona tion was 0.10% per amu and the common lead used for correction had an isotopic composition corresponding to an age of 1,150 ma, following the stacey & kramers (1975) two-stage model. the rb-sr whole rock analyses for the skflfjellet granite-gabbros were carried out in 176 yu. a . balasov et al. 0 0. 6-11 1120/ s u b concordant age of 1.6 1.8 2.0 2.2 207pb1235u fig. 10. u-pb concordia diagram for the gabbroic samples, 6-1 and 6-2. the same laboratory at apatity (teben'kov et al. 1996). the samples were dissolved in hci + hf + hc104, the residue was dissolved in hci and put in a column with dowex 50x3 (200400 mesh) resin. rb and sr contents were determined by isotope dilution and mass-spectro metry. the sr isotope compositions were deter mined by an mi 1201-t mass spectrometer. the blanks of rb and sr are 2 and 8 ng, respectively. the analytical error for 87rb/86sr is assumed to be 1.5% and that of 87sr/s6sr 0.04%. the age calculation was made using the program of ludwig (1991b). samples of the deilegga group were analysed for rb-sr whole rock dating by geochron laboratories of krueger enterprises inc., cam bridge, massachusetts, u.s.a. the samples, made as free of carbonate vein material as possible, were crushed and homogenised to -80 mesh whole rock powders prior to analysis. errors on rb and sr concentrations, analysed by xrf, are approximately ?0.5%, and those of 87sr/86sr are given as 2 sigma in table 4. the sr analyses were normalised to 86sr/88sr = 0.11940. analyses of the nsb 987 standard gave 0.710240 (?lo) during the period. description of zircons the zircon grains used for the u-pb dissolution analyses, from samples 5-2 (from the second block-bearing layer), 6-1 and 6-2 (from the third layer) of the skplfjellet subgroup, show similar shapes, euto subhedral shapes with facets (111) and 110), often flattened along one of the (110) faces and having smooth surfaces. most grains are zoned. pink coloured, transparent grains were handpicked for the analyses. zircons from samples 5-3, 6-1 and 6-2 were used for the single-grain pb evaporation analyses. they are similar in shape, euto subhedral, but range in colour from yellow (sample 5-3) to pink (sample 6-1). prism facets (100) are better developed than (110), and (101) pyramidal facets are dominant over (211), corresponding to the s 24-25 type of pupin (1980). these are character istics of high temperature zircons like those found in calcalkaline series rocks. they do not exhibit any visible core, and the clearest grains are entirely inclusion free. zircon grains were also separated from two micaceous schists of the isbj~rnhamna group (3 fractions from 4-1; and one fraction from 4-3). all grains are anhedral to subhedral, with round shapes and rough surfaces. the zircon grains from 4-1 are dark grey to black, due to graphite inclusions. those of 4-3 are less rounded, rose to light rose in colour, and translucent due to cloudy outer parts. some grains are weakly zoned. the character of zircons from the schists suggests a detrital origin. zircons from sample 4-3 may be primarily magmatic judging from their idiomor phically zoned structure. results and interpretation zircon ages. the results of isotopic analyses by the u-pb dissolution method are shown in table 2. one zircon sample from specimen 6-1-1 (a tonalitic rock from the third block-bearing layer) is almost concordant and defines a "7pb/206pb age of 1,154 t 21 ma (fig. 10 ). the zircon of 6 2-2 (a syenite from the third block-bearing layer) plots above the concordia, suggesting possible u loss during processing sample or reversely discordant fraction due to u loss or pb gain in nature. thus the z07pb/206pb age of 1,072 2 13 ma for this sample is assumed to be the minimum age. sample 5-2 (a tonalite from the second layer) exhibits a 207pb/206pb age of ca.1,300 ma by the u-pb dissolution method (table 2). a three-grain pb evaporation analysis was performed on sample 6-1 (fig. 11f and g). the two-heating steps provide similar results, taking rb-sr whole rock and u-pb zircon datings of the granitic-gabbroic rocks 177 table 3. pb isotope ratios of the granitic-gabbroic rocks of the sk4lfjellet subgroup, analysed by the pb evaporation method. analyses 2 of 5-3 were not calculated because of bad quality of measurements. sample 6-2 was analysed using a cameca tsm 206 mass spectrometer, while the others were performed using a finnigan mat 262 mass spectrometer. abbreviations in the second column from the left: numbers = analysis number, eh = euhedral, br = brown colour. third column: a, b, c, etc., signify different blocks of the same evaporation step. analysis step z"pb/mpb zu7pb/zmpb error z"7pb/zo6pb error s a m p 1 e s zircon (ampere) (measured) (measured) (2 sigma) (corrected) age, ma (2 sigma) 5-3 6-1 5-3 1, eh,br, 2.6, a 2.6, b 2.6, total 2.8, a 2.8, b 2.8, c 2.8, d 2.8, e 2.8, total 3.0, a 3.0, b 3.0, c 3.0, total 2, eh,br, 2.6, a 2.6, b 2.6, c 2.6, d 1 2.6, e 2.6, f 2.6, total 2.8, a 2.8, b 2.8, c 2.8, d 2.8, e 2.8, total 1, eh, 2.8, a 2.8, b 2.8, c 2.8, d 2.8, e 2.8, total 3.0, a 3.0, b 3.0, c 3.0, d 3.0, total 6-2 1, eh, br, 2.6 2.8 5324 5326 5325 17056 17018 17238 17345 17324 17214 39714 38731 37975 38806 125976 124053 120834 l230476 116139 113776 120210 11 7020 132122 140763 143423 79336 122533 14184 14258 13954 13891 139.58 14049 23818 25891 27032 27469 26798 1731 10512 0.08055 0.08078 0.08067 0.07815 0.07836 0.07839 0.07840 0.07836 0.07833 0.07845 0.07836 0.07811 0.07834 0.07929 0.07929 0.07926 0.07920 0.07939 0.07952 0.07933 0.07900 0.07870 0.07866 0.07852 0.07839 0.07865 0.08080 0.08032 0.08011 0.08013 0.08033 0.08034 0.08007 0.08117 0.08009 0.08060 0.08062 0.08551 0.07887 3 6 5 4 6 2 3 5 2 3 3 2 3 9 8 9 6 11 10 4 30 33 24 24 23 13 23 15 13 10 9 9 11 19 26 41 24 12 31 0.07811 0.07836 0.07822 0.07744 0.07765 0.07770 0.07772 0.07766 0.07684 0.07819 0.07809 0.07794 0.07807 0.07928 0.07889 0.0785 1 0.07866 0.07852 0.07839 0.07865 0.07994 0.07941 0.07919 0.07918 0.07939 0.07935 0.07955 0.08061 0.07960 0.08017 0.08023 0.07722 0.07752 1150 1156 1153 1133 1138 1139 1139 1138 1138 1152 1149 1145 1149 1179 1169 1162 1163 1161 1 is4 1161 1196 11x2 1177 1177 1182 1181 1185 1212 1187 1201 1203 1127 1135 3 7 7 2 1 2 2 i 3 2 3 2 3 6 15 17 14 12 13 13 12 8 8 6 5 9 5 8 13 30 20 12 19 the analytical errors in account (table 3). the first step at 2.8 amperes yielded a mean age of 1,181 ? 9 ma, and the highest temperature step at 3.0 amperes gave an age of 1,203 rt 20 ma. the correction of primary and contaminant common pb is limited in this sample because it has a high 206pb/204pb ratio. a single grain from sample 6-2 was also analysed (fig. 11h and k) by two-step heating and yielded similar ages of 1,127 t 12 and 1,135 t 19 ma (table 3). two single-grain analyses of sample 5-3 were made by the pb evaporation method. the first grain yielded ages of 1,153 t 7 ma, 1,138 2 3 ma and 1,149 t 3 ma in three heating steps at 2.6a, 2.8a and 3.oa, respectively (fig. 11a, b and c). the second grain shows slightly older ages from 1,179 2 6 ma to 1,161 t 13 ma by the 2.6a and 2.8a heating steps (fig. 11d and e). zircon grains were handpicked from two isbjgrnhamna schists, three fractions from 4-1 178 yu. a . balaiov et al. 60 40. 20. h z 10 1100 d " ' 9 + m .: r 'c r" r b 80. 60. 40 20. 0 1101 * 00 1: h 20 15 i a 5 i 11 4 0 20 -a z 5 1: c 1 lj 11oc ma t 1150 : 2 1' fig. 11. histograms of pb isotope ages, analysed by the zircon evaporation method. a, b and c: sample 5-3, the first grain. d and e: sample 5-3, the second grain. f and g: sample 6-1, 3-grains together. h and k sample 6-2, single grain. and one from 4-3, and analysed by the u-pb dissolution method (fig. 12). the 207pb/206pb ages of 4-1 range from 1,503 to 1,749 ma (table 2). assuming the three fractions from sample 4-1 form a coherent system, it is possible to draw a discordia approximately between 2,300 ma and 360 ma, but the error is very high. the zircons from sample 4-3 plot away from the discordia which is defined by the 4-1 fractions. the 4-3 zircon grains have a more magmatic morphology than the 4-1 grains. the common pb content of this zircon sample is also distinctly lower, 8.2 ppm, than those of the 4-1 fractions, which range from 12.7 to 19.3 ppm. the 207pb/206pb age of sample 4-3 is 1,503 2 39 ma. rb-sr whole rock age. nine rocks from the skilfjellet subgroup were analysed for rb and sr isotopes, including 5 tonalites, 1 syenite and 3 rb-sr whole rock and u-pb zircon datings of the granitic-gabbroic rocks 179 (samples 6-2, -3, -4, -5 and 5-4) yields 1,278 % 100 ma, with mswd = 10.2 and initial 87sr/86sr ratio = 0.7060 2 7 (fig. 13). the ob tained rb-sr whole rock errochron age is apparently older than the zircon ages, but has a large error. within the range of this error, it is conformable with most of the zircon ages. the rb/sr whole rock isotope analyses of the phyllites of the deilegga group do not give a good isochron (table 4, fig. 14). the best estimated age is about 600 ma, with a very large error (mswd = 70, 2-sigma error = f 450 ma). the initial 87sr/86sr ratio corresponding to this age is 0.716 2 51. tuble 4. whole rock rb and sr isotopic compositions of the granitic-gabbroic rocks of the skalfjellet subgroup (nos. 5and 6-) and the metasediments of the deileq,, group (b, c, d). normalisation factor: "sr/%r = 10 and sr/% = 0.1194. no. rb ppm sr ppom s7rbp6sr 87sr?6sr error 5-1 10 78 1.3160 0.7477 5-2 15 135 0.3267 0.7109 5-3 13 191 0.1858 0.7109 5-4 20 268 0.2185 0.7097 61 14 385 0.1154 0.7088 6-2 63 174 1.0874 0.7259 6-3 14 494 0.0837 0.7074 6-4 39 532 0.2189 0.7103 6-5 15 477 0.0927 0.7073 b 61 125 1.4173 0.7291 c 144 44 9.6062 0.7961 d 148 43 10.0726 0.8051 2 8 4 9 8 7 10 9 10 7 7 8 gabbros (classification after fig. 4) (table 4, fig. 13). no isochron can be defined by the whole rock rb-sr isotope data, probably due to different degrees of partial resetting by later metamorph ism. the datapoints for rocks with 87rb/86sr ratios between 0.1 and 0.4 are scattered and suggest an open system. one tonalite, 5-1 (with the highest sioz content) and one syenite, 6-2 (with the highest k20 content) have 87rb/86sr ratios of more than 1.0. an errochron including all samples yields an age of 1,259 2 170 ma with mswd= 34 (fig. 13). another errochron using 5 points mica schists lsbjernhamna group 0.20 t 0.0 0.4 0.8 1.2 1.6 2.0 2.4 207pb/235u fig. 12. u-pb concordia diagram of the isbj~rnhamna schists. discussion and conclusions the eimfjellet group and isbj~rnhamna group have been considered older than the oldest regional precambrian tectonic event, the werens kioldian, by birkenmajer (e.g., 1992), but no age has been known for this event. the granite-gabbro complex in the skdlfjellet subgroup of the eimfjellet group has been considered to be the product of granitisation, but new observations on field relations and petrog raphy show that these rocks are exotic blocks incorporated into the eruptive rocks, which make up most of the subgroup. the chemical composi tions of the tonalitic rocks indicate that they are i-type, calcalkalic, within-plate-granite. the felsic volcanic clasts in the pyttholmen unit at vimsodden (fig. la), which is the lateral equivalent of the upper skllfjellet subgroup, has been dated by the u-pb zircon dissolution method (balasov et al. 1995), and preliminary rb-sr whole rock age determinations were made for the isbjarnhamna schists (gavrilenko et al. 1993). the results suggest a felsic magmatism at ca. 1,200 ma, and an inherited zircon age of ca. 2,500 ma, and a greenschist-amphibolite facies meta morphism at ca. 930-936 ma. the present age determinations for the skilfjel let granitic-gabbroic rocks by the zircon dissolu tion and evaporation methods yielded reasonably consistent results. the zircons of sample 6-1 are subconcordant with an age of 1,154 2 21 ma in the u-pb diagram and the error of this determina tion overlaps with the most reliable evaporation zircon age, of 1,181 ? 9 ma from the same rock. the old age with the smallest error from sample 5 180 yu. a. balasov et al. granite-gabbros 6-5 skhlfjellet subgr =2 errochron age: 1,278+/-100 ma mswd= 10.2 initial 87srpsr ratio=0.7060+/-7 " . i i . 3, 1,179 f. 6 ma, is similar. these ages are conformable with previous results from the felsic volcanic clasts of vimsodden and constrain the magmatic age of the granitic-gabbroic rocks of the skllfjellet subgroup. the blocks of the granitic gabbroic rocks are considered to be consolidated when the host eruptive rocks were exploded. the present results can not distinguish the time difference between these two events and may suggest that there is no recognisable age differ ence between them. slightly younger ages, around 1,130-1,150 ma, were obtained from samples 6-2, a gabbro, and 5 3, a tonalite. these probably reflect discordant zircons. metasediments deilegga group 0.78 0.76 / 1 initial 87srpsr ratio= 0.716+/-51 0 2 4 6 8 10 ' ' . ' . ' j ' " 87rbla@sr fig. 14. rb-sr errochron of the metasediments from the deilegga group. fig. 13. rb-sr errochron of the skelfjellet granitic-gabbroic rocks. an rb-sr errochron yielded an age of 1,278 ? 100 ma which is in rough agreement with the zircon ages. the age of 1,300 ma from sample 5-2 (table 2) remains debatable. it could reflect older radiogenic lead. the poorly constrained u-pb zircon upper intercept age for the isbjarnhamna schists, ca. 1,503-1,750 ma, as old as 2,300 ma, suggests the presence of paleoproterozoic detrital material, similar to the earlier results of balasov et al. (1995). the lower intercept age of ca. 360 ma suggests caledonian or younger readjustments. the sedimentary protoliths of the isbjamhamna schists are possibly of mesoproterozoic age, containing paleoproterozoic zircons as detrital grains, and metamorphosed during the grenvillian time, as suggested by the rb-sr whole rock age obtained by gavrilenko et al. (1993) and balasov et al. (1995). the apparent latest neoproterozoic rb-sr whole rock age of the deilegga group phyllites, ca. 600 ma, can be explained as partial readjust ment of the proterozoic isotope system by low grade metamorphism during the caledonian event. it is evident that this group is overlain by the slyngfjellet conglomerate (fig. 2) with a distinct angular unconformity, but its age-relation ship to the eimfjellet and isbjamhamna groups is still unknown. acknowledgements. logistic support during field works was provided by the polar marine geological expedition, lomo nosov, russia and norwegian polar institute, oslo, norway. rb-sr whole rock and u-pb zircon datings of the granitic-gabbroic rocks 181 financial help from french-norwegian cultural cooperation fund is also acknowledged. constructive comments of a. johansson, naturhistoriska riksmuseet, stockholm, are deeply appreciated. skr. 137. 39 pp. gayer, r. a., gee, d. g., harland, w. b., miller, j. a., spall, h. r., wallis, r. h. & winsnes, t. s. 1966: radiometric age determinations on rocks from spitsbergen. norsk polarinst. hoel, a. 1918: rapport preliminare de ]’expedition norwegi enne de 1918 au spitsbergen. la geogr. paris 32,231-235. hughes, c. j. 1973: spilites, keratophyres, and the igneous spectrum. geol. mag. 109(6), 513-527. irvine, t . n. & baragar, w. r. a. 1971: a guide to the chemical classification of the common volcanic rocks. can. references balashov, yu. a,, teben’kov, a. m., ohta, y., larionov, a. n., sirotkin, a. n., gannibal, l. f. & ruyngenen, g. i. 1995: grenvillian u-pb zircon ages of quartz porphyry and rhyolite clasts in a metaconglomerate at vimsodden, southwestern spitsbergen. polar research 14(3), 291-302 (balashov = balasov). barker, f. 1979 trondhjemites, definition, environment and hypotheses of origin. pp. 1-12 in barker, f. (ed.): trondhjemites, dacites and related rocks. elsevier, amster dam. birkenmajer, k. 1959: report on the geological investigations of the homsund area, vestspitsbergen, in 1958. part i, hecla hoek formation. bull. polish acad. sci. ser. chim. g601. g6ogr. 7 (2), 129-136. varsovie. birkenmajer, k. 1975: caledonides of svalbard, the western part of the barents sea, and the continental margin of scandinavia. pp. 265-322 in nairn, a. e. m., churkin, m. jr. & stehli, f. g. (eds.): the ocean basins and margins, 5, the arctic ocean. birkenmajer, k. 1992: precambrian succession at hornsund, south spitsbergen: a lithostratigraphic guide. stud. geol. polonica 98, 7-66. birkenmajer, k. 1993: redefinition of parts of the vimsodden subgroup and the deilegga group (proterozoic), southwest wedel jarlsberg land, spitsbergen. bull. pol. acad. sci. 41(3), 137-159. birkenmajer, k. 1994: correlation of proterozoic and cam brian lithostratigraphic units across torellbreen, wedel jarlsberg land, spitsbergen. bull. pol. acad. sci. 42(4), 247-264. birkenmajer, k. & narehski, w. 1960: precambrian amphibo lite complex and granitization phenomena in wedel-jarls berg land, vestspitsbergen. stud. geol. polonica 4, 37-82. brown, g . c. 1982 calc-alkaline intrusive rocks: their diversity, evolution, and relation to volcanic arcs. pp. 437-461 in thorpe, r. s . (ed.): andesites. springer. chappell, b. w. & white, a. j. r. 1974: two contrasting granite typpes. pacific geol. 8, 173-17. czerny, j., kieres, a., manecki, m. & rajchel, j. 1993: geological map of the southwest part of wedel jarlsberg land, spitsbergen. 1:25,000. institute of geology and mineral deposits, university of mining and metalurgy, cracow. 61 pp. debon, f. & le fort, p. 1983: a chemical-mineralogical classification of common plutonic rocks and associations. transact. roy. soc. edingb. earth sci. 73, 135-148. gavrilenko, b. v., balalov, ju. a., teben’kov, a. m. & larionov, a. n. 1993: u-pb ranneproterozojskij vozrast “reliktovogo” cirkona iz vysokokalievych kvarcevych por firov, zemli vede1’-jarlsberga, ju.z. spicbergena (u-pb early proterozoic age of “relict” zircon from high potassium quartz porphyries of wedel jarlsberg land, southwest spitsbergen). geochim. 1, 154-158. jour. earth sci. 8, 523-548. kober, b. 1986: whole-grain evaporation for 207pb/zmpb age investigations on single zircons using a double-filament thermal ion source. contr. miner. petr. 93, 482490. krogh, t. e. 1973: a low contamination method for hydrothermal dissolution of zircons and extraction of u and pb for isotopic age determinations. geoch. cosmoch. acta 37, 485-494. la roche, h., de leterrier, j., grandclaude, p. & marehal, m. 1980: a classification of volcanic and plutonic rocks using r1 and r2 diagram and major-element analyses, its relationships and current nomenclature. chem. geol. 29, 183-210. ludwig, k. r. 1991a: pbdat-a computer program for processing pb-u-th isotope data, version 1-20, u.s.g.s. open-file report, 88-542. ludwig, k. r. 1991h: isoplot-a plotting and regression program for radiogenic isotope data. version 2-55, u.s.g.s open-file report, 9 1 4 4 5 . maniar, p. d. & piccoli, p. m. 1989: tectonic discrimination of granitoids. bull. geol. soc. am. 101, 635-643. ohta, y. & dallmann, w. k. (eds.) 1994 geological map of svalbard 1:100,000, sheet b12g, torellbreen. degital version, norsk polarinst. temakart ( up-dated version 1996). orvin, a. k. 1940 outline of the geological history of spitsbergen. skr. svalb. ishav. 78. 57 pp. pearce, j. a., harris; n. b. w. & tindle, a. g. 1984: trace element discrimination diagrams for the tectonic interpreta tion of granitic rocks. jour. petr. 25, pt. 4, 95g983. pupin, j. p. 1980: zircon and granite petrology. contr. miner. petr. 73, 207-220. ringwood, a. e. 1974: the petrological evolution of island-arc systems. j. geol. soc. lo&. 130, 183-204. smulikowski, w. 1965: petrology and some structural data of lower metamorphic formations of the hecla hoek succes sion in hornsund, vestspitsbergen. stud. geol. polon. 18, 7-107. smulikowski, w. 1968: some petrological and structural observations in the hecla hoek succession between werenskioldbreen and torellbreen, vestspitsbergen. stud. geol. polon. 21, 97-161. stacey, j. s. & kramers, j. d. 1975: approximation of terrestrial lead isotope evolution by a two-stage model. earth planet. sci. lett. 26, 207-221. streckeisen, a. & le maitre, r. w. 1979 a chemical approximation to the modal qapf classification of the igneous rocks. neu. jhrb. menr. abhd. 136, (2), 169-206. teben’kov, a. m. 1983: pozdnedokembrijskie magmaticheskie formacii zapadnogo poberegja spicbergena (late pre cambrian magmatic formations of vestspitsbergen). veslnik leningradskogo gosudarsmennogo universiteta, no. 4 (24), 88-93. seasonal distribution of harp seals (phoca groenlandica) in the barents sea t o r e haug. kjell t o r m o d nilssen, nils 01en and vladimir potelov' haug. t., nilssen. k. t., bien. n. & potelov. v. 1994: seasonal distribution of harp seals (phoca groenlandica) in the barents sea. polar research 13(2), 163-172. the distributional patterns of barents sea harp seals (phoca groenlandica) throughout the year are presented based o n existing literature and recent norwegian and russian field observations. the harp seals breed in february-march in the white sea. moulting occurs during april to june in the white sea and southern barents sea. feeding.behaviour is closely related to the configuration and localisation of the drifting sea-ice during summer and autumn (june-october) when the seals follow the receding ice edge, retiring gradually northwards and northeastwards in the barents sea. the southward movement of the population in autumn probably takes place in november prior to the advance of the ice edge, and is likely related to food-search. apparently, most barents sea harp seals seems to concentrate at the southern end of their range in winter and spring. t . haug and k . t . nilssen. norwegian institute of fisheries and aquaculture, breivika, p . o . box 2511, n-9002 tromsb, norway; n. 0 i e n , institute of marine research, p . o . box 1870 nordnes. n-5024 bergen, norway: v . potelov. polar research institute of marine fisheries and oceanography (pinro), 6 knipovich street, 183763. murmansk, rmsia. introduction three stocks of harp seals (phoca groenlandica) inhabit the north atlantic ocean, whelping respectively at newfoundland and in the gulf of st. lawrence (the northwest atlantic stock), off the east coast of greenland (the greenland sea stock). and in the white sea (the barents sea stock) (sergeant 1991). all three stocks have been subjected to exploitation, and have been managed separately. recent studies of stock identities based on studies of allozymes have revealed significant differences between the northwest atlantic stock on one side and greenland sea and the barents sea stocks on the other, while no evidence of differences between the two latter was observed (meisfjord & naevdal in press). most likely, some mixing of these two stocks occurs. it has been hypothesised that harp seals from the barents sea and from the greenland sea intermix during the summer in waters off svalbard (sivertsen 1941). such mixing between these two breeding stocks on feeding grounds is confirmed from more recent tagging experiments (oien & 0ritsland 1991). in the barents sea, the harp seal is the most abundant seal species. harp seals are traditionally i authorship equal. caught by soviet/russian and norwegian sealers in march-may in the east ice, i.e., the pack-ice areas in the white sea and southeastern barents sea (wollebaek 1907; iversen 1927; sivertsen 1941; jakovenko 1967). norwegian estimates sug gested a total stock size in 1978 of ca. 800.000 seals producing approximately 170,000 pups annually and increasing at an annual rate of about 5% at that time (benjaminsen 1979). in 1980, soviet aerial surveys confirmed a pup production similar to the norwegian 1978 estimates (anon. 1992). however, later russian surveys and russian and norwegian age composition data indicated that a reduction may have prevailed in recruitment after 1985 (anon. 1992, 1994; kjellqwist et al. in press). large bycatches of harp seals in gill-net fisheries during the harp seal invasions in norweg ian coastal waters through 1986-1988 (haug et al. 1991) may have influenced the 1986-1988 cohorts, which show a consistent low representation in norwegian catches of moulting harp seals in the east ice in recent years (kjellqwist et al. in press). recruitment of one year old seals to the moulting stock did not improve significantly until 1992 (kjellqwist et al. in press), and russian aerial surveys, conducted in 1991, resulted in an esti mate of 141,600 breeding females in the white sea that year (anon. 1994). 164 t. haug et al. although there are uncertainties connected t o the present abundance of the barents sea harp seals stock, there is no doubt that this numerous species is an important predator. field studies designed to identify the composition and quantity of prey consumed and to evaluate the ecological role of the barents sea harp seals are now in progress (nilssen et al. 1991,1992,1994, in press). the intention is to include the species into a multispecies assessment model (multspec) for the barents sea (see bogstad & tjelmeland 1990). knowledge of the distribution of the harp seal stock is necessary t o reveal its role in the eco system. by combining data on abundance and distribution, knowledge of energy requirements of individuals, and geographical and seasonal variation in diet and its energy content, it is pos sible to perform an evaluation of the impact of harp seals on commercially important fish species (and also the impact of fisheries on seals). the pre sent study summarises current knowledge of the migrational patterns and the seasonal distribution of harp seals in the barents sea and adjacent waters, based mainly on recent norwegian and russian field observations. additionally, infor mation from available literature on the seasonal distribution of barents sea harp seals has been consulted (wollebaek 1907; smirnov 1924; iversen 1927; capskij 1938, 1961; sivertsen 1941; popov 1970). materials and methods information on incidental sightings of harp seals since 1968 in the norwegian and barents seas was extracted from a database at the institute of marine research (imr), bergen, comprising data received from imr research vessels, reports from norwegian fishing vessels, reports from norwegian coast guard vessels and reports from russian research vessels. these reports include observation date, position and in some cases also approximate herd size and comments on activity and behaviour. in addition to these incidental sightings, harp seals distribution data were also available from norwegian and russian surveys where all observed marine mammals were recorded. infor mation from these surveys includes observation date, position and approximate number of harp seals observed. norwegian line transect surveys, designed t o estimate minke whale (balaenopfera acuforo strata) abundance, were conducted in the north, norwegian and barents seas during the summer (july-august) in 1987, 1988 and 1989 (see 0 i e n 1989, 1990, 1991). in 1992 (july-august) and 1993 (april-may, june-july, august-sep tember) norwegian scientific surveys designed to catch minke whales along predetermined line transects were conducted in five subareas ex tending from lofoten at the norwegian coast in the south, along the kola coast in the east, around bjarnaya and at the western coast of spitsbergen in the north (haug 1993; haug et al. 1994, in press). all marine mammals observed, including harp seals, were recorded during each of these surveys. during norwegian ecological harp seals inves tigations conducted at different parts of the year (nilssen et al. 1991,1992,1994, in press), all harp seals observations were recorded. surveys were carried out in february 1993 in the drift ice in the southeastern barents sea, in march-april 1992 in varangerfjord, north norway, in june 1991 in open waters and along the fringe of the pack-ice between novaja zemlja and hopen, in sep tember 1990 and 1991 and in october 1992 in the pack-ice belt between svalbard and franz josef land. in december-january 1965/1966 and 1966/ 1967, in june 1965, in july 1960, 1965 and 1992, in september-october 1967, in november 1987 and in december 1960 russian shipboard surveys were carried out to explore the distribution of seals (including harp seals) and polar bears (ursus matirimus) from the white sea in the south, along coasts and the fringe of the pack ice in the barents sea and in the kara sea (along the eastern coast of novaja zemlja). in july 1983, in august 1981 and 1983, in september 1983 and in october 1987, russian aerial surveys were carried out in the barents sea, covering large areas from the kola coast in the south to the fringe of the pack ice in the north by flying transects in order t o explore the distribution of seals (including harp seals) and polar bears. each harp seal observation given in fig. 1 gives no information about the numbers of animals observed and therefore an observation might rep resent a single seal or a group of seals. due to the gregarious nature of harp seals, the latter is the more usual, in some cases with groups of several thousand seals. this gregarious occur seasonal distribution of harp seals 165 of spitsbergen (fig. 1). occurrence in june of large numbers of harp seals in their latest stages of moulting along the edge of the drift ice in the central barents sea southeast of hopen (mainly west of 40"e) was verified during a norwegian harp seal survey in mid-june 1991 (nilssen et al. 1992). particularly many norwegian observations are available from july, mainly due to enhanced effort caused by the extensive minke whale surveys in 1987-1989 and 1992-1993 ( 0 i e n 1989,1990,1991; haug et al. 1994, in press). the 1989 minke whale sighting survey had the most complete coverage of the barents sea area ( 0 i e n 1991), and harp seals were seen along the edge of the ice east of svalbard and to a considerable extent also pelagically in the central and southeastern bar ents sea. russian observations made during an aerial survey in 1983 and a research vessel survey in 1991 confirm the pelagic occurrence of harp seals to the west of spitsbergen, and also the occurrence of considerable numbers of animals occurring on the ice between b j ~ r n ~ y a and hopen. rence is very characteristic of the species, and makes misinterpretations with other seal species rather unlikely. abundance estimates and the exact distribution of harp seals cannot be given based on the present observations. first, because the surveys do not cover the entire barents sea area simultaneously at any of the given periods. second, because the sighting effort varies between time periods and areas and in the case of incidental sightings, is not quantifiable. the present study can only give the trends in dis tribution and annual migrational patterns. results january-february very few incidental sightings of harp seals are available from january to february. this is partly due to the restricted period of daylight. however, research surveys conducted off the kola coast and in the southeastern parts of the barents sea (northeast of cape kanin) and in the pechora sea in 1966, 1967 (russian) and 1993 (norwegian) yielded the presence of considerable numbers of harp seals in these areas (fig. 1). during the ecological studies in february 1993 approximately 75% of the captured harp seals were subadults (nilssen et al. 1994). only a few stragglers were recorded on the norwegian coast during this period. march-april in march and april, harp seals were seen north west of the mouth of the white sea, in var angerfjord on the norwegian coast, to the east of b j ~ r n ~ y a and off the western coast of spitsbergen (fig. 1). may in may almost all harp seals were seen in the area between the coast of north norway and spitsbergen (fig. 1). june-july in june and july, harp seals were seen in open and pack-ice waters from novaja zemlja to the eastern coast of north norway, along the pack ice belt in the north and along the western coast august-september in august and september, the distribution of harp seals seems to depend very much on the localisation of the pack-ice edge. russian obser vations made during aerial surveys with sub stantial coverage in 1981 and 1983 revealed harp seals confined t o the pack-ice belt east of b j ~ r n ~ y a and hopen in the central part of the barents sea both in august and september (fig. 1). the august observations are supported by norwegian observations which also include harp seals observed in open waters and in the franz josef land archipelago (fig. 1). during norwegian field studies of harp seals ecology in the barents sea in september 1990 and 1991, it was observed that the seals were confined to the northernmost parts of this ocean (between svalbard and franz josef land at approximately 78"-8oon), and always close to also to some extent within the pack-ice belt (fig. 1). during minke whale investigations in 1993, some harp seals were also seen west of spitsbergen. october the majority of harp seal observations from october were located between the 76"n and the 166 t . haug et al. 8 1' 77' 7 3' 69' 6 5' 81' 77' 73' 69' 65' 8 1' 77' 7 3' 69' 65' 10' 20' 30' 40' 50' 60' 70' 10' 20' 30' 40' 50' 60' 70' 8 1' - 77 ' 73' 69' 65 ' 81' 77' 73' 69' 65' 8 1' 77' 7 3' 69' 6 5' 10' 20' 30' 40' 50' 60' 70' 10' 20' 30' 40' 50' 60' 70' seasonal distribution of harp seals 167 8 1' 77 ' 73' 69' 65' 8 1' 77' 73' 69' 65' 10' 20' 30' 40' 50' 60' 70' 10' 20' 30' 40' 50' 60' 70' 81' 77' 73 o 69 ' 65 ' 8 1' 77' 73' 69' 65' 10' 20' 30' 40' 50' 60' 70' 10' 20' 30' 40' 50' 60° 70' fig. i. norwegian (circles) and russian (squares) sightings of harp seals (singles or groups of animals) at different times of the year in the barents sea. sightings data were recorded either incidentally or during special norwegian minke whale and harp seal surveys and russian marine mammals surveys; the shaded areas are those covered by the two latter survey types. 79"n parallels between spitsbergen and novaja zemlja, always confined t o the ice edge (fig. 1). the norwegian observations are almost exclus ively from a harp seal ecology investigation survey performed in october in 1992. harp seals were then observed t o migrate from approximately 79"n and southwards to ca. 76"n within a period of two weeks due to low temperatures which caused the ice cover to move rapidly southwards. russian surveys performed using planes and research vessels in 1987 confirm an easternly dis tribution of harp seals along the ice edge. november during the first week of november 1987, russian research vessel surveys observed most harp seals to be confined to the fringe of the pack ice between 45"e and the northwest coast of novaja zemlja (fig. 1). some seals were also observed 168 t. haug et al. further south along the western coast of novaja zemlja, while no seals were observed along the southwest coast of this island, in the southeastern barents sea or along the kola coast (fig. 1). december russian ship board surveys in december 1960 and 1965 revealed harp seals confined to pack ice in the areas between the southern coast of novaja zemlja and cape kanin (in the pechora sea) (fig. 1). discussion january-february the presented observations of harp seals in the southeastern barents sea in this period are con sistent with previous knowledge that by the end of january and in early february the majority of mature seals, first the females and somewhat later the males, will habitually move south towards and into the white sea to prepare for the breeding season which includes whelping (c. 20 february to 5 march) and ca. 12 days lactation (iversen 1927; sivertsen 1941). in winter the north and northeastern parts of the barents sea are usually covered with dense pack ice (loeng 1989), which makes occurrence of harp seals in these areas rather unlikely. in january and february the majority of barents sea harp seals seems to be concentrated near the southern end of their range, including the areas southwest of novaja zemlja, the northern white sea and kola coast (capskij 1961; popov 1970). march-april in early march large numbers of mature seals concentrate in the white sea to breed (iversen 1927; sivertsen 1941). during lactation and for some time after weaning, females and pups will move passively with the drifting ice (popov 1970). this drift, which is influenced by prevailing cur rents and winds, is usually northwards and brings the pups out into the barents sea in april. in some years, however, constant northerly winds in march and april may move the pack-ice south wards, bringing pups to the southern shores of the white sea. according to popov (1970), the passive drift of pups from the southern part of the white sea estuary northwards past cape kanin may take from 20 to 50 days, depending upon the velocity of the ice drift. this means that the pups will be present in the southeastern parts of the barents sea during the first half of april which is also the time they are assumed t o start inde pendent feeding (sivertsen 1941). after the breeding period, ending with mating ca. two weeks after whelping (iversen 1927; siv ertsen 1941), an emigration from the white sea and subsequent feeding migration westwards along the kola coast to varangerfjord in north norway of the mature females is known to occur (nilssen et al. in press). the present observations from varangerfjord are consistent with such a migrational pattern. our observations (fig. 1) from the northern areas indicate that harp seals may also occur quite far from the southern coastal areas of the barents sea in march-april. throughout april, however, most seals are presumed to migrate towards the moulting lairs inside and outside the white sea mouth. in these areas, all age groups of the popu lation are known to be gathered by the end of april (nazarenko & timoshenko 1974; benja minsen 1979; kjellqwist et al. in press). may in early may harp seals occur in their moulting areas both inside and outside the white sea mouth ( t a p s k i j 1961; nilssen et al. in press). during may, however, the seals seem to start moving north and northwestwards into the barents sea, a migration which leaves virtually no animals south of cape kanin after 15 may (sivertsen 1941). the immediate stimulus of the animals t o go northwards is assumed to be the disappearance of ice from the white sea (capskij 1961). during and after completed moult, the seals seem t o follow the receding ice edge, retiring gradually northwards in the barents sea and poss ibly, at least to some extent, also into the kara sea (smirnov 1924; capskij 1938, 1961; wiig 1988). smirnov (1924) emphasised that some seals may remain at finnmark and kola coasts in spring before they leave for open waters. the presented observations from may confirm this view. june-july the summer distribution of harp seals will change almost continuously in relation to changes in the seasonal distribution of harp seah 169 configuration and location of the driftin pack early autumn distribution of harp seals in the ice. from compiled statistics of catches, {apskij barents sea will change in relation t o changes in (1938, 1961) reported that in june, harp seals the configuration and location of the borders of (some of them still moulting) were both found off the drifting ice (see capskij 1961). the southwestern coast of novaja zemlja and along the ice edge in the central parts of the barents sea southeast of hopen island but west october-november of ca. 40"e as also seen in our material. obser vations of harp seals in drift ice waters southeast of hopen were also made in june 1973 by christensen (1974). during whale surveys in july 1974 and 1975 (benjaminsen et al. 1976), large numbers of harp seals were observed off the west coast of novaja zemlja as well as southeast of hopen and west of spitsbergen. this is consistent with our findings (fig. 1). it has been hypothesized that harp seals from the barents sea and from the greenland sea intermix during summer in waters off sval bard (see sivertsen 1941). such feeding ground mixing between these two breeding populations is confirmed also from more recent tagging experi ments (0ien & britsland 1991). it is impossible, based only on observations, to ascertain whether the harp seals observed west of spitsbergen in the present material belong to the greenland sea or the barents sea populations, or both. august-septem ber observations of harp seals in the franz josef land archipelago, off the northernmost coasts of novaja zemlja, and in the northern kara sea were made in august-september 1979 (j. naz arenko, sevpinro, arkhangel'sk, russia, pers. comm.). these, and the observations presented here (fig. 1) are consistent with previous assump tions, stating that in august and september the harp seals disperse along almost the entire ice edge from spitsbergen to the northeastern parts of the kara sea including part of the franz josef land (eapskij 1961). interestingly, despite con siderable sighting effort in the areas in august, only a few harp seals were seen along the southern coasts of the barents sea and over the continental shelf along the west coast of spitsbergen (fig. 1). the latter could indicate that the greenland sea and the barents sea stocks have started to move westwards and eastwards, respectively, at this time of the year. certainly, the ice was distributed further south in the barents sea in september in 1981 and 1983 than in 1990 and 1991. our data, thus, support the view that the late summer and the observed trend of a northeastward migration of harp seals in august is even stronger in october when our observations are consistent with pre vious assumptions that the harp seals start to move eastwards along the fringe of the pack ice towards novaja zemlja in october-november (eapskij 1961). however, the exact time and patterns of migration from the feeding areas in the northern parts of the barents sea towards the white sea are not known in detail. the presented data confirm the presence of seals along the ice fringes in the north as late as in early november, but also with some animals apparently on their way southwards. the southward migration route of the animals is assumed t o be very close to the western coast of novaja zemlja (capskij 1961). capskij (1961) suggested that the herds of harp seals, which during fall and winter comprise mixed schools of mature and immature males and females, move t o southern novaja zemlja in the beginning of october and usually remain along the southwestern coast of the island during late fall and early winter. the presented observation data set may indicate that this southward migration takes place somewhat later (novem ber). since the movement of the population to the southern parts of the barents sea takes place before the advance of the ice edge, it has been suggested that the migrational mechanism at this time of the year is of a trophic character where the seals move southwards to search for food (capskij 1961). december the december observations clearly resemble those from january-february. eapskij (1961) suggested that in some years harp seals might also occur in the white sea and along the kola coast from november on, depending on variable weather, ice conditions, and food availability. the annual winter occurrence of harp seals in norwegian coastal waters (nilssen et al. in press) suggests that a more westerly early winter dis tribution may have been common in recent years. 170 t. haug et al. i , 25" 30' 35' 4 i 1 i 45' 50" 55* fig. 2. annual migrational patterns of the barents sea harp seals. the extensions of the breeding and moulding areas are indicated. its range, primarily in the southeastern parts of the barents sea and in the white sea where breeding and moult occur (capskij 1961; naz arenko & timoshenko 1974; benjaminsen 1979; kjellqwist et al. in press; nilssen et al. in press). between breeding and moult, a feeding migration the annual migrational patterns the apparent annual migrational route of the barents sea harp seals is summarised in fig. 2. in winter and spring (december-may), the stock seems to be concentrated at the southern end of seasonal distribution of harp seals 171 of mature females from the white sea and west wards along the kola coast, at least to var angerfjord in north norway, seems to occur in march-april (see nilssen et al. in press). in may, during and after completed moult, the seals start to migrate north and northwestwards in the barents sea. from june the seals are dis tributed both in open waters in the central and southern parts of the barents sea and in pack-ice waters from novaja zemlja in the east, along the pack-ice belt to the north and along the western coast of spitsbergen. in august, a northeastward migration of the animals appears t o occur in that they seem to disappear both from the western coast of spitsbergen and from the central and southern parts of the barents sea. this north and eastwards trend in migration and distribution of the seals is even more apparent in october and november. both the distribution and feeding of the harp seals during the autumn (september-october) seem to depend very much of the location of the pack-ice edge when the seals follow the receding ice edge, retiring gradually northwards and eastwards in the barents sea (nilssen et al. 1991, 1992). the exact time and patterns of the late autumn migration from the northern parts of the barents sea towards the southern areas are not known. our observations confirm that the migration takes place before the southward advance of the drifting pack ice, probably during november. in decem ber the harp seals appear to have moved south wards where they were observed between the southwestern coast of novaja zemlja and cape kanin. acknowledgements. thanks arc due to s. hartvedt and f. strand for technical assistance, to b. gullikscn for comments on the manuscript. and to r. t. barrett for language correction. the harp seals investigations were funded by the norwegian council of research. project no. 4001-2800.083. punching and verification of russian data were funded through akup project no. 73 (det kongclige nreringsog cnergidepartement). references anon. 1992. report on the joint ices/nafo working group on harp and hooded seals, copenhagen. 14-18 october 1991. ices cm 1992/asscss:5. 41 pp. anon. 1994. report of the joint ices/nafo working group on harp and hooded seals, copenhagen. 15-21 september 1993. ices cm 1994/asscss:5. 35 pp. benjaminsen, t. 1979. pup production and sustainable yield of white sea harp seals. fisk.dir. skr. ser. hau.unders. 16. 551-559. bcnjaminscn, t., bcrlund, j . , christensen, d., christensen, i., huse, i. & sandnes. 0. 1976. merking, observasjoner og adfcrdsstudicr av hval i barentshavet og ved svalbard i 1974 og 1975. fisken hau 76(2). 9-23. bogstad, b. & tjelmeland, s. 1990. estimation of predation mortality of capelin using a cod-capelin model for the barents sea. ices cm 1990/h:16. 32 pp. eapskij, k. k. 1938. novejshie dannyc o rasprcdelenii belmor skoj rasy grcnlandskogo tjulenja vne belmorskogo bassejna (new data on distribution of the white sea race of harp seals outside the white sea basin). problemy arktiki 4 , 105-131. capskij, k. k. 1961 (1962). nektorye kkologifeskie obos novaniia sczonnoj dynamiki areala belomorskoj populjatsii grcnlandskogo tjulerja (pagophoca groenlandica) (some bio logical factors determining seasonal changes in distribution of the white sea harp seals population (pagophoca groen landica)). trudy sovejfanija, ichtiol. komissii akad. nauk. sssr 12. 150-163 (transl. ser. fish. res. bd canada 380. christensen, i . 1974. undcrsekelser av vagchval i barentshavct og vcd 0 s t og vestgrenland i 1973. fiskets gang 60. 278 286. haug, t. 1993. studies of minkc whale (balaenoptera acu torostrata) ecology in the northeast atlantic: description of the norwegian 1992 scientific catch activities. lnt. whal. comm. sc/45/na2. 26 pp. haug. t . , kreyer, a. b.. nilssen. k. t.. ugland, k. i. & aspholm. p. e . 1991 harp seal (phoca groenlandica) invasions in norwegian coastal waters: age composition and feeding habits. ices 1. mar. sci. 48, 363-371. haug, t., lindstrem, u . , nilssen, k. t. & rettingen. i . 1994. studies of minke whale (balaenoprera acutorostrata) ecology in the northeast atlantic: description of the 1993 scientific catch operations and preliminary results from stomach analyses and resource surveys. lces cm 1994/n:14. 53 pp. haug, t . , gjosaethcr, h., lindstrem, u . & nilsscn, k. t. in press: diets and food availability for northeast atlantic minke whales (balaenoptera acutorostrata) during summer in 1992. ices j. mar. sci. iverscn. t . 1927. drivis og selfangst. arsber. vcdk. norg. fisk. 1927(2). 1-84. jakovcnko, m. j. 1967 (1969). belmorskaja populjarsija grcn landskogo tulenja i perspektivy c e ekspluatacii (the white sea population of harp seals and the prospects of its exploi tation). trudy pinro (proceedings of polar research insti tute of marine fisheries and oceanography) 21. 19-26 (transl. ser. fish. res. bd. canada 1321, 1-35). kjcllqwist. s . a., haug, t. & britsland, t . in press. trends in age composition. growth and rcproductivc parameters of barcnts sea harp seals. phoca groenlandica. ices 1. mar. s c i . locng, h . 1989. ecological features of the barcnts sea. pp. 327-365 in: rey, l. & alexander, v. (eds.) proceedings of the sixth conference of the comitk arctique international 13 i5 may 1985. e. j. brill, lcidcn. mcisfjord, j . & naevdal, g. in press. using isoelectric focusing to discern enzyme variation in northeast atlantic stocks of harp seals. hereditas. nazarenko, y . 1. & timoshenko, y. k. 1974. age structure and sex ratio in the white sea population of pagophoca groenlandica as an index of efficiency of protective measures. zoologicheskii zhurnal. 53(2), 256-262. nilssen, k. t., haug, t. & potelov, v. 1991. field studies of harp seals (phoca groenlandica) distribution and feeding ecology in the barents sea in september 1990. ices cm 1991/n:3. 23 pp. 1-22). 172 t. haug et al. nilssen, k. t., haug, t., potelov, v. & timoshenko, y. k. 1992. preliminary data on feeding and condition of barents sea harp seals (phocu groenlundicu) throughout the year. ices cm 1992/n:5. 23 pp. nilssen, k. t., ahlquist, i., eliassen, j-e., haug, t. & lindblom, l. 1994. studies of food availability and diet of harp seals (phocu groenkundica) in the southeastern barents sea in february 1993. ices c m 1994/n:12. 24 pp. nilssen, k. t., haug. t., potelov, v., stasenkov, v. & timo shenko, y. k. in press. food habits of harp seals (phocu groenlundicu) during lactation and moult in march-may in the southern barents sea and white sea. ices 1. mur. sci. 0ien, n. 1989. sighting estimates of northeast atlantic minke whale abundance from the norwegian shipboard surveys in july 1987. rep. in;. whal. comm. 39, 417-421. bien, n. 1990. sighting surveys in the northeast atlantic in july 1988: distribution and abundance of cetaceans. rep. int. whul. comm. 40,49%511. bien, n. 1991. abundance of the northeast atlantic stock of minke whales based on shipboard surveys conducted in july 1989. rep. int. whal. comm. 4 1 , 433-437. bien, n. & britsland, t. 1991. resources of harp seals (phocu groenlundicu) tagged as pups in the greenland sea: pup production and dispersion patterns. joint ices/nafo working group on harp and hooded seals, copenhagen, popov, l. a. 1970. soviet tagging of harp and hooded seals in the north atlantic. fitk.dir. skr. ser. hau.wtders. 16, 1-9. sergeant, d. e. 1991. harp seals, man and ice. can. spec. publ. fish. aquut. sci. 114. 153 pp. sivertsen, e. 1941. on the biology of the harp seals phocu groenlundicu erxl. investigations carried out in the white sea 1925-1937. huulrddets skr. 26. 166 pp., 10 pl. smirnov, n. 1924. on the eastern harp seals phocu (pugophocu) groenlandicu var. oceunicu lepechin. t r o m p mu. arsh. wiig, 0. 1988. grdnlandssel og selinvasjon. hva vet vi hva tror vi? nuiuren 1988 ( 2 ) . 35-41. wollebiek, a. 1907. uber die biologie der seehunde und die seehundjagd in europaischen eismeer. rupp. p . u . r h n . cons. ini. explor. mer 8, 5-82. 14-18 october 1991. wp sea-33. 21 pp. 47(2), 1-11. bookreviews25(2).indd 181polar research 25(2), 181–188 widely read and acknowledged. however, the fi rst and last chapters are also an interesting read and give a nice basis for evaluating the biological and ethnographic material presented in the volume’s middle section, although now and again they are redundant. the book contains an interesting and eclectic collection of black and white illustrations including portraits, historical photographs, and technical and biological drawings. otto fabricius was a cleric, philologist, naturalist and ethnographer. much of his scholarly work stems from the relatively short period of his life spent as a missionary in greenland (1768–1773). his observations during these fi ve years and the experiences he had with greenlandic people clearly left a great impression on fabricius that lasted until his death. unlike many missionaries of his time, fabricius left the european colonytown where he was posted and lived in a greenlandic inuit community. he resided in a house built of stones, turf and timbers and learned the language and the ways of the people. much of their hunting culture revolved around knowing the habits of seals, and hence the people were a wealth of knowledge to fabricius in his faunal and ethnological studies. fabricius is undoubtedly best known for his publication fauna groenlandica (1780), but the work translated by kapel in this book, published a decade later (1790–91), allowed fabricius to expand greatly on the seal material presented in the earlier book. fabricius’s detailed description of the seals of greenland focuses fi rst and foremost on the harp seal or greenland seal (phoca groenlandica), describing: nomenclature; appearance and morphology; distribution (occurrence); behaviour; variation in occurrence and movements; breeding; feeding; predators; hunting methods; utilizabook reviews review of otto fabricius and the seals of greenland. meddelelser om grønland: bioscience 55, by finn o. kapel (2005). copenhagen: danish polar center. 150 pp. isbn 87-90369-77-7. kit m. kovacs norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, kovacs@npolar.no. in this three part volume finn kapel presents us with 1) a brief biography of fabricius, 2) a translation of his treatise on the seals of greenland and, fi nally, 3) a refl ection on the contribution of fabricius as a seal naturalist/scientist. i concur with dr kapel’s belief that the key paper is the second one. this work on greenland’s pinnipeds has until now been available only in danish and german and certainly deserves to be more skull of the “hook-snouted seal”, now known as the grey seal (halichoerus grypus). the drawing illustrated fabricius’s detailed description of the seals of greenland (1791). (reproduced with permission of the danish polar center.) portrait of otto fabricius. (reproduced with permission of the danish polar center.) 182 book reviews tion; parasites; and synonyms. ringed seals (pusa hispida), harbour seals (phoca vitulina), hooded seals (cystophora cristata) and bearded seals (erignathus barbatus) are presented similarly, although more briefl y. fabricius also gives short synopses of four additional “species” reported to him by the greenlanders. three of these animals are either mythical beasts or some sort of biological oddity such as albino specimens. the fourth species summary is the fi rst scientifi c account of the grey seal (halichoerus grypus), which fabricius describes primarily from material in his possession from an island off the danish coast. given the era in which fabricius was writing, his restricted time in greenland, and limited travel in the north, his biological accounts are remarkably insightful. occasionally, they are defi nitively incorrect, such as when he says, “as for the breeding of the harp seal, the matingtime is beyond all doubt in august” when in reality harp seals mate in march. but fabricius can be forgiven for using the size of the embryo in september to back-calculate the time of mating: delayed implantation was unknown in the 1700s. other small slips can be similarly accounted for. he is probably not credited as often as his work warrants; perhaps this book by finn kapel will help correct this situation. if allen’s history of north american pinnipeds (1880) or similar books are on your shelf, otto fabricius and the seals of greenland undoubtedly also deserves a place there. references allen, j. a. 1880: history of north american pinnipeds. a monograph of walruses, sea-lions, sea-bears and seals of north america. washington, d. c.: u.s. geological and geographical survey of the territories. fabricius, o. 1780: fauna groenlandica. (fauna of greenland.) copenhagen(?): j. g. rothe, hafniae & lipsiae. fabricius, o. 1790–91: udførlig beskrivelse over de grønlandske sæle, første og andet stykke. (detailed description of the seals of greenland, parts one and two.) copenhagen: skrivter af naturhistorie-selskabet. review of le monde polaire, mutations et transitions, under the direction of mariefrançoise andré (2005). paris: ellipses– carrefours. 187 pp. isbn 2-7298-2683-1. in french. bernard lefauconnier place du mollard, f-38700 le sappey en chartreuse, france, b.lefauconnier@wanadoo.fr. as mentioned on its back cover, le monde polaire, mutations et transitions comprises part of a collection (carrefours) intended for students of geography, history and the social sciences as well as for a wider public interested in understanding the changes our world is undergoing. other volumes in the series concern, for example, water in the arab world, large cities of north america and international commerce. twelve authors have collaborated on the book. the work is divided into two parts, made up in total of 11 chapters and six brief inset texts. the fi rst part is supposed to present some general aspects of the subject, regional aspects being introduced in the second part. seven of the book’s 11 chapters concern the indigenous peoples of the circumpolar region and constitute the heart of the volume. chapter 3 explores how the inuit conceive of—and are integrated with—their environment. chapter 4 discusses the transition from a subsistence economy to the present situation in the canadian arctic, focussing on nunavik, northern québec. major social transformations are described in chapter 10, with examples from the central canadian arctic. chapter 5 describes the emergence of the sense of an inuit identity, the creation of the inuit circumpolar conference and the building of inuit managerial and administrative competence, especially in the nunavut and nunavik territories, northern canada. chapter 7 concerns the transformation of greenlandic society. the situation of the saami, the subject of chapter 8, is unusual in that this population is represented in four countries: norway, sweden, finland and russia. the relationship between the saami and the norwegian state is described. the small-numbered indigenous ethnic groups—mainly reindeer herders—of the russian arctic are briefl y presented in chapter 9. only two chapters are devoted chiefl y to the 183polar research 25(2), 181–188 physical environment: chapter 1 presents a review of some recent research on the melting of glaciers and the related sea level rise while chapter 2 discusses the impacts of climate change through the metamorphosis of polar landscapes. one chapter (6) describes the development of polar tourism and chapter 11 summarizes past and present scientifi c activities in the antarctic. the limited space allotted to the environment in this book is regrettable. impacts related to climate change are not confi ned to glaciers and landscapes. in a book with academic intentions, references to the arctic climate impact assessment and the arctic monitoring and assessment programme would have been minimally necessary. in chapter 1, one of only two chapters devoted to the environment, some of the research results that are discussed are erroneously interpreted. for example, arendt et al. (2002) estimated the contribution to sea level of alaskan glaciers from the mid-1950s to the mid-1990s to be 0.14 ± 0.04 mm per year. this is equivalent to 5.6 ± 1.6 mm over the period, not 5 cm. another example is where the chapter’s author (incidentally, also the book’s editor), referring to rignot et al. (2003), writes that patagonian glaciers contribute even more than alaskan glaciers to sea level rise. in fact, rignot et al. said that the contribution from the patagonian glaciers is larger than that of alaskan glaciers per unit area. this is an important distinction. finally, the chapter mentions glacier surging but this phenomenon is evidently not understood by the author. there are other fl aws. chapter 6 takes into account the local and regional environmental impacts of tourism but does not mention the contribution to global pollution generated by the transportation of voyagers from low latitudes to the polar areas. in two places—a short inset in chapter 10 and a section heading in chapter 4— the use of the phrase “welfare state” (état providence) seems inappropriate. the texts discuss social and economic transformations and largescale interventions by the canadian central power. the “welfare state” must have been developed to try to counter-balance negative social effects of these transformations and is not in itself the cause of these negative effects. this is a strange book. the title claims to embrace the polar world but only a single chapter concerns the antarctic. the chapters discussing the environment merely skim lightly over a narrow slice of this important topic, without any real look at current climatic changes or the fact that the arctic and antarctic have already been affected by pollution, including ecotoxins, coming from sources elsewhere in the world. even with these drawbacks le monde polaire has value: there are few books presenting a broad picture of circum-arctic peoples. social, economic and geopolitical problems and the similarities and differences in the relationships between far northern indigenous peoples and the modern states that encompass them are briefl y but, in general, clearly described. i was particularly captivated by the subject of chapter 3—“corps inuit, espace géographique et cosmologique”, which opened for me, as an occidental scientist, a new window on the arctic and enriched my vision of it. references arendt, a. a., elchemeyer, k. a., harrison, w. d., lingle, c. s. & valentine, v. b. 2002: rapid wastage of alaska glaciers and their contribution to rising sea level. sciences 297, 382–386. rignot, e., rivera, a. & cassasa, g. 2003: contribution of the patagonia ice-fi elds of south america to sea level rise. science 302, 434–437 review of the north pole, by kathan brown (2004). san francisco, ca: crown point press. 504 pp (xi-xvi). isbn 1891300-18-0. thor b. arlov research and innovation unit, norwegian university of science and technology, no-7491 trondheim, norway, thor.arlov@ntnu.no. at fi rst glance a medium brick sized book entitled the north pole seems a promising read to anyone interested in the arctic, such as this reviewer. unfortunately it does not quite deliver according to expectations, presuming you expect solid information about the polar region. if, however, you are particularly interested in the personal experiences of arctic tourists with a dash of environmental concern, this book may not be a complete waste of time. the author kathan brown is the founder and 184 book reviews director of a renowned san francisco-based fi ne art printing press and publishing house. she has previously published various books on art and artists. however, her professional or personal connection with the polar regions are, as it were, shrouded in northern mists. the introduction to the north pole is not very helpful about her motives for writing this book. it appears she took part in a trip to the north pole sponsored by the american museum of natural history aboard the russian nuclear powered icebreaker yamal in 2002. the following year, she spent a week on a coastal cruise around svalbard. her experiences during these two trips have obviously inspired the book. in addition she has read a number of works about various arctic subjects and talked to some knowledgeable people, but to call this a thoroughly researched book would be stretching it. admittedly, brown seems to have no pretences in this direction. the north pole is voluminous in pages—a little more than half a thousand. the genre is a bit diffi cult to decide as the author mixes forms. since the voyage seems to be the structuring element, i suppose the book might be placed in the travel literature category. following a brief introduction that attempts to explain the somewhat odd composition of the book, there are eight main chapters. the fi rst seven are devoted to the north pole trip on the yamal. each of them is divided into three sections: a personal narrative by the author; excerpts from the journal of fridtjof nansen from the fram expedition; and a conversation with various people rendered in verbatim form. the last chapter is on the visit to svalbard and also contains a conversation, but— quite understandably—no excerpts from nansen. in between there are more than 100 photographs, the vast majority taken by the author herself. to the extent that there are any main themes at all, the issue of climate change and the question who was the fi rst on the north pole (if indeed peary cheated) recur frequently with slight variations throughout the book. if i were to be very polite i would call this unusual lay-out interesting, but to be honest i am rather put off by what seems to be a lack of serious effort making this book. the author’s own, original contribution represents the lesser part of the manuscript. the “journey” sections written by brown make up some seventy pages, or less than 15 % of the book. the photographs, also the work of brown, constitute nearly a quarter of the book. of the remaining 60 %, the excerpts from the journal of nansen fi ll almost 100 pages. the conversations or interview sections, where brown acts as “moderator”, occupy over 150 pages. at the end of the book there is a rudimentary time line, a short bibliography and a decent index. the only map in the book is a poor sketch of the arctic. although neatly organized, this book is in effect a compilation of somewhat disparate elements. by themselves the journey sections work fairly well; brown is a good observer and masters the style of a well-read journalist. she makes a pretty good job of popularizing science. this is the kind of prose one might expect to fi nd in for example national geographic: a personal account supplemented by factual information, or vice versa. the conversation sections function less well. their consistently verbatim form leaves the question open whether editing has taken place or not. anyway, stronger editing would have been desirable—considerable parts of the conversations are just plain small talk between fellow travellers. i kept wondering why the reader is invited to listen in. some of the contributors have more to offer, but the knowledge and capacity of participants like, for instance, arctic climate impact assessment director gunther weller and scott polar research institute archivist bob headland, could have been exploited far better in more elaborate interviews. in general, brown does not seem to distinguish between the substantial and the trivial in her role as moderator. for example, rendering an exchange of opinions concerning rock bands or suvs leaves me, in this context, cold. a more selective approach would certainly not have been amiss. nansen’s journal of his and hjalmar johansen’s dramatic attempt to reach the north pole from fram and their subsequent wintering on franz josef land in 1895–96 is a classic in arctic literature, but should rather be read in the original and in extenso. brown’s excerpts seem out of context and do not lend her account authority—just extra pages. i feel the use of nansen borders on literary theft when the author does not even make the effort of paraphrasing or commenting. finally, the photographs are for the most part unimpressive and appear to be ordinary amateur snapshots. considering the author’s professional background the reproduction is disappointing; the colours seem washed out and the subjects are fre185polar research 25(2), 181–188 quently unsharp. variations on ice fl oes are only interesting to a certain point, which brown oversteps. it does not make things better that there are no captions to the pictures, leaving the reader to guess when, where and why they were taken. in all fairness, kathan brown’s the north pole is probably not intended for well-read polar enthusiasts. it is indeed hard to imagine that readers of polar research will fi nd very much of interest in this book. it is simply too superfi cial with regard the factual parts and has too little to offer in literary terms. in my opinion, neither the gracious contributions of some prominent savants of the arctic nor the extensive quoting of nansen’s diary help salvage this north pole voyage from wreckage. at the uttermost ends of the earth: the physiology of polar fi shes, edited by anthony p. farrell & john f. steffensen (2005). amsterdam: elsevier. 396 pp. isbn 0-12350446-5. andrew clarke biological sciences, british antarctic survey, high cross, madingley road, cb3 oet cambridge, uk, accl@bas.ac.uk. ecologists and physiologists have always been interested in organisms living in extreme environments because of the light they shed on fundamental problems, and the general public has long been fascinated by animals living in climates so inhospitable that unprotected humans would rapidly perish. the pioneering physiologists of the early 20th century had quickly recognized that teleost fi shes with their dilute blood would have real problems in the cold waters of the polar regions, and when johan ruud collected the fi rst scientifi c specimens of an icefi sh he was able to confi rm that there really did exist a group of polar fi shes with no blood pigment. the scene was thereby set for an exploration of the physiology of polar fi shes, and this remains a vibrant fi eld of research to this day. the latest volume of the prestigious fish physiology series brings together a group of distinguished workers in the area of polar fi sh and provides a state-of-the-art survey of our understanding of the physiology of a group of organisms that have successfully adapted to one of the most physiologically challenging marine environments on the earth. the opening chapter (devries & steffensen) provides a brief overview of the marine environment of the polar regions, emphasizing the marked differences between the arctic and antarctic as much as their similarities, and thereby defi ning an important theme for the rest of the book. as well as differences in topography, bathymetry, riverine input and oceanography, attention is drawn to the very different tectonic, climatic, glacial and evolutionary histories of the two polar regions. the latter are fundamental to understanding the very different fi sh faunas of the arctic and antarctic, which are described in exemplary fashion in the second chapter by møller, nielsen & anderson. it is refreshing to see due attention being paid to the systematic and biogeographic aspects of the fauna in a volume devoted primarily to physiology, for this is essential to any complete understanding of evolutionary aspects of the physiology. the systematic treatment also covers all depths, thereby providing a broad context for the traditional (but not universal) concentration by physiologists on the more easily sampled shallow waters. the physiological chapters start with a thorough review of current knowledge of the metabolic biochemistry of polar fi shes by pörtner, lucassen & storch. the main themes of this chapter are the central role played by oxygen in shaping both thermal limits and lifestyle, and the trade-offs inherent in the utilization of energy in a strongly resource-limited environment such as the polar seas. the strengths of this chapter are the way physiological processes are set in an environmental context, the use of a wide range of model organisms, and the links between physiology and ecology. antifreeze proteins and freezing avoidance are reviewed by devries & cheng. the physiological challenge to teleost fi sh living in polar regions was recognized in the 1960s: even with an elevated blood salt concentration, polar fi sh are under cooled by almost 1k. whilst this may seem a small interval, because polar oceans contain ice crystals freezing of these fi sh would be inevitable in the absence of a protective mechanism. the existence of antifreeze glycoproteins and proteins in polar fi sh was quickly established by elegant work by art devries himself, but almost four decades later we are still unravelling the complexities of this system. in addition 186 book reviews to providing a masterly summary of the classical work, the authors also discuss areas of active current research making this the best current review of freezing avoidance in polar fi sh. in the next chapter steffensen concentrates on the respiratory system and metabolic rate; this chapter is thus closely allied to the earlier one by pörtner and colleagues but takes a quite different perspective by concentrating on the organismal rather than the molecular level. steffensen revisits the arguments over the existence of metabolic cold adaptation (mca) in polar fi shes, and does so in a thorough and balanced manner. once a fi sh has taken up oxygen, it then needs to move this oxygen around the body and the circulatory system is described by axelsson. a major factor here is the increase in blood viscosity at low temperature, and it is likely that selection for reduced circulatory costs coupled with the increased solubility of oxygen at low temperatures is what drove the evolution of reduced hematocrit in many polar fi shes and the complete loss of haemoglobin in one group, the icefi sh family channichthyidae. a key feature of this chapter is the discussion of the control of heart rate, setting the antarctic notothenioids in the wider context of non-polar fi sh. wells covers blood gas transport and haemoglobin, principally from studies of notothenioids but also setting the results in a wider context. wells also revisits the topic of mca, coming to a less defi nitive conclusion than steffensen. davison describes the skeletal musculature and locomotion, again principally based on studies of notothenioids. data are compared with warmer water fi sh and the differences related to ecological factors such as growth rate and buoyancy. in exploring the various ways in which temperature may limit muscle performance in polar fi sh, davison also discusses the limitation of mitochondrial atp supply, which links this chapter nicely to that by pörtner and colleagues. the fi nal chapter in the book is an authoritative review of the nervous system of polar fi shes by macdonald & montgomery. how does this volume rate overall? i believe it succeeds in providing a thorough, timely and authoritative survey of the physiology of polar fi shes. it will fi nd a place in my library and i have already found myself making extensive use of it. it is a pity that not every author has taken the opportunity to cover both arctic and antarctic studies, for the book does tend to concentrate on studies of notothenioids in many places. important and interesting as these fi sh are, they are confi ned to the southern hemisphere and physiologists have much to learn from thorough comparative studies. nevertheless this is an excellent summary of current knowledge and will remain for some time the place to go to learn about the physiology of fi shes living at high latitudes. review of the north pole was here: puzzles and perils at the top of the world, by andrew c. revkin (2006). boston: kingfi sher. 128 pp. isbn 0-7534-5993-0. helle v. goldman norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, goldman@ npolar.no. ever wondered what the men’s toilet at camp borneo, a temporary russian camp on the ice about 96 km from the north pole, consists of? in the north pole was here, andrew revkin reveals this—“a waist high igloo-style wall of ice blocks” (p. 16)—and other details of the fi eld conditions experienced by scientists who carry out research near the very top of the world. using revkin’s own visit to the north pole environmental observatory—a science camp set up every year on the ice about 48 km from the north pole—as a jumping off point, the book describes the arctic and our past and ongoing efforts to understand it. climate change is a major theme. other topics, like early exploration of the region and the earth’s shifting magnetism, are also covered. in an enchanting chapter called “the imagined pole”, revkin describes early notions of the far north. we learn, for example, that in ancient hindu / buddhist cosmology, the stars in the sky were tied by ropes of wind to the north star, which was positioned above a gigantic mountain that constituted the world’s centre. four landmasses, divided by great rivers, lay around that centre. three thousand years ago, greek historians supposed that there was a society of “hyperboreans”: “an immortal race of people who lived in happiness and warmth beyond the source of the north wind” (p. 28). (this is sure to raise 187polar research 25(2), 181–188 a smile from readers who, like me, reside north of the arctic circle.) as late as the 19th century some maintained that the earth was hollow, with large openings into the interior at the north and south poles. according to another tenacious and surprisingly recent theory, the north pole was topped by a huge iron cone, which was the source of the planet’s magnetism. the bulk of the north pole was here is set in the present. revkin focusses his account on the scientists who undertake polar research, how they do it and the diverse challenges they face. one chapter begins with this riveting opening: “six of the world’s leading experts at solving arctic riddles are on their knees on the sea ice thirty miles from the north pole, stumped by three broken bolts” (p. 89). the chapter goes on to relate how the bolts were replaced and the winch repaired, and how the equipment contributes to our knowledge of the ocean, atmosphere and climate in the arctic. the heroes of revkin’s book are polar scientists and the divers, technicians and others who work with them. in the harsh environment of the arctic, research teams must combine “the brainpower of scientists with the brute strength of furniture movers, the wile of small-town mechanics, the courage (or recklessness) of extreme athletes, and the willingness to carry a shotgun to ward off polar bears” (p. 92). without oversimplifying its subject matter, the north pole was here makes science accessible to the nonspecialist reader. the slim book is aimed particularly at young adults but will also appeal to their parents. the chapters are short, the type is large and the text is amply illustrated with photographs, diagrams, maps and other illustrations. excerpts from new york times stories relating to the arctic (about half by the author) are sprinkled throughout the book. an award-winning journalist, revkin has been reporting on environmental issues for the new york times for over a decade. some readers may recognize the author’s name from his recent coverage of the bush administration’s attempt to stifl e jim hansen, director of nasa’s goddard institute for space studies, after hansen publicly called for prompt reductions in greenhouse gas emissions. the north pole was here is well timed: 2007-08 is an international polar year, during which scientifi c resources around the world will be concentrated on the arctic and antarctic. its antecedents have taken place in 1882-83, 1932-33 and 1957-58. revkin traces the polar year project back to the inspiration of the austrian karl weyprecht. upon returning from an arctic expedition in 1874, the explorer and scientist was determined to persuade the scientifi c institutions of many nations that it was crucial to coordinate meteorological and geophysical research and to share the resulting data. weyprecht’s efforts bore fruit, though it was posthumous: he died the year before the fi rst polar year. fourteen stations ringing the arctic were established by 11 countries (norway, sweden, finland, austria, netherlands, france, germany, uk, russia, canada, us). revkin observes that the fi rst polar year marked a major change in the culture of science, which became more open, collaborative and self-critical. this book is written with the american reader in mind. for example, the arctic ocean near the north pole is described as “two miles deep— deep enough that ten empire state buildings could be stacked beneath us” (p. 11). that the book tilts decidedly toward a youthful american readership is appropriate. the american association for the advancement of science (1990) has made the point that most schoolchildren in the us are not science literate. it behooves the generation of americans about to come of age to develop a basic understanding of the causes, signs and potential impacts of climate change, as well as to improve their knowledge of other major environ188 book reviews mental problems confronting us, such as natural habitat destruction and loss of biodiversity. the scientists who are spotlighted in the north pole was here are perhaps among the fi rst people to discern the magnitude of human impacts on the natural world; our children may be among the fi rst to have to cope with these changes during their lifetimes. revkin entitled his book after a sign erected by a scientist at the north pole observatory. the joke plays on the fact that the ice supporting the temporary science camp is in constant motion. less amusing are computer simulations according to which the ice on the surface of the arctic ocean may be gone by the end of this century. as is well known in the scientifi c community, this would have radical consequences for the world. let us hope that the north pole was here— a lively paean to polar scientists—is the kind of book that engages young minds in the arctic and in science itself. reference american association for the advancement of science 1990: science for all americans. new york: oxford university press. accessed on the internet at www.project2061.org/ publications/sfaa/online/sfaatoc.htm. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <feff00560065007200770065006e00640065006e0020005300690065002000640069006500730065002000450069006e007300740065006c006c0075006e00670065006e0020007a0075006d002000450072007300740065006c006c0065006e00200076006f006e0020005000440046002d0044006f006b0075006d0065006e00740065006e0020006d00690074002000650069006e006500720020006800f60068006500720065006e002000420069006c0064006100750066006c00f600730075006e0067002c00200075006d002000650069006e00650020007100750061006c00690074006100740069007600200068006f006300680077006500720074006900670065002000410075007300670061006200650020006600fc0072002000640069006500200044007200750063006b0076006f0072007300740075006600650020007a0075002000650072007a00690065006c0065006e002e00200044006900650020005000440046002d0044006f006b0075006d0065006e007400650020006b00f6006e006e0065006e0020006d006900740020004100630072006f0062006100740020006f0064006500720020006d00690074002000640065006d002000520065006100640065007200200035002e003000200075006e00640020006800f600680065007200200067006500f600660066006e00650074002000770065007200640065006e002e00200042006500690020006400690065007300650072002000450069006e007300740065006c006c0075006e00670020006900730074002000650069006e00650020005300630068007200690066007400650069006e00620065007400740075006e00670020006500720066006f0072006400650072006c006900630068002e> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <feff0041006e007600e4006e00640020006400650020006800e4007200200069006e0073007400e4006c006c006e0069006e006700610072006e00610020006e00e40072002000640075002000760069006c006c00200073006b0061007000610020005000440046002d0064006f006b0075006d0065006e00740020006d006500640020006800f6006700720065002000620069006c0064007500700070006c00f60073006e0069006e00670020006600f60072002000700072006500700072006500730073007500740073006b0072006900660074006500720020006100760020006800f600670020006b00760061006c0069007400650074002e0020005000440046002d0064006f006b0075006d0065006e00740065006e0020006b0061006e002000f600700070006e006100730020006d006500640020004100630072006f0062006100740020006f00630068002000520065006100640065007200200035002e003000200065006c006c00650072002000730065006e006100720065002e00200044006500730073006100200069006e0073007400e4006c006c006e0069006e0067006100720020006b007200e400760065007200200069006e006b006c00750064006500720069006e00670020006100760020007400650063006b0065006e0073006e006900740074002e> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice research note gastroliths in the harp seal phoca groenlandica erling sverre nordby norday, e. s . 1995: gastroliths in the harp seal phoca groenlandica. polar research 14(3), 335-338. an adult harp seal, caught by accident in a gill net during the peak of the seal invasions along the northern coasts of norway (1986/87), was found to have eaten 2.466 kg of stones with masses up to 265 g. different theories to why harp seals on occasion deliberately eat stones, with particular emphasis on the hypothesis that these may aid in the physical breakdown of fish flesh and'hard hsh bones, are discussed. erling sverre nordey, department ofarctic biology and institute of medical biology, universiry of trams@, breioika, n-9037 trams(, norway. gastroliths (stones or pebbles in the stomach) have been found in many species of pinnipeds, such as the california sea lion zalophus cali fornianus, the harbor seal phoca vitulina and the walrus odobenus rosmarus (emery 1941; gjertz & wiig 1992). southern elephant seals mirounga leonina, moreover, have been observed to contain as much as 35 kg of stones in their stomachs (ling & bryden 1981). among the ice-breeding seals in the northern hemisphere, both the ringed seal phoca hispida and the bearded seal erignatus barbatus have been found on occasion to contain gastroliths in their stomachs (kumlien 1879). a number of theories have been put forward to explain the function of gastroliths in pinnipeds (see king 1983; riedman 1990). this note doc uments the first observation of gastroliths in harp seals phoca groenlandica. it provides some sup port for the theory that gastroliths aid in the physical breakdown of large prey (mathews 1929) and that they may also serve to grind up stomach parasites (hamilton 1933). during the winter of 1986-1987, there was a dramatic increase in the number of invading harp seals along the coast of northern norway com pared t o previous years (haug et al. 1991). mark recapture experiments suggest that the invading harp seals mainly belonged to the white sea stock (@en & 0ritsland 1991), which during the winter is normally distributed within the barents sea and northwards to the pack ice between spitsbergen and novaja zemlja. the harp seal reported in this study was caught by accident and drowned in a gill net, at the peak of the invasion, on 10 march 1987 in troms county (69'39" 18'41'e). the adult male had a curvilinear length from snout to tail-tip of 195cm and a blubber thickness of between 30 and 45 mm along the ventral midline. sternum blubber thickness was 40 mrn, indicating that the condition of the animal was normal for the season (sivertsen 1941). the body mass was estimated to about 150 kg, based on data on male body lengths and masses in march (sivertsen 1941). the content of the seal stomach was ana lysed and found to contain large amounts of stones, together with some otoliths, fish bones and nematodes (fig. 1). the total mass of the' stomach content was 2.496 kg and consisted of 2.466 kg of stones (1.6% of body mass), 29 g of fish bones/otoliths and 1 g of parasitic nematodes. a total number of 139 stones, both flat and round, varying in mass (0.1-265.1 g) and diameter (0.5 7.7cm), were found (fig. 2). based on the otoliths, which were minimally eroded, the prey was identified as cod gadus morhua. using a length-mass relationship for cod otoliths (hac konen 1986), it was calculated that the total mass of the fresh undigested prey had been about 2.45 kg, while individual fish masses had varied between 0.3 kg and 0.7 kg. the large amount of gastroliths present in the harp seal stomach suggests that these are swal lowed intentionally and not by accident. laws (1956) reported that 84% out of 139 sou 336 e. s. n o r d ~ y thern elephant seal stomachs contained sand and stones. based on the observation that most of the solid material has been eaten just before the animals came ashore for a prolonged fasting period, he suggested that the stones served to relieve “hunger pangs” by providing the stomach muscles with bulk to relieve the contractions. the theory that pinnipeds may eat stones to relieve the sensation of hunger does not apply to the present incident since the animal had recently fig. 1 . the stomach content of an adult harp seal caught in a gill net during the seal invasion along the coast of northern norway during the winter of 198611987. shown are 2.466 kg of gastroliths and in the lower right corner some nematodes, otoliths (on darker paper) and fish bones. a bar with 1 cm divisions is shown at the bottom. eaten and was in good-condition. moreover, stomachs of fasting harp seals collected in april at the outlet of the white sea (n = 150) did not contain gastroliths (personal observation). the “ballast” theory, which implies that gastroliths help the seal to regulate buoyancy and balance while swimming and diving (hamilton 1933), is also an unlikely explanation because in the spring harp seals are considerably leaner than in autumn (nilssen et al. 1992a), and they would thus have no problem with a strong buoyant force due to a large blubber mass. a more relevant explanation for the current incident was proposed by mathews (1929) who suggested that gastroliths aid in the physical breakdown of food. spalding (1964) supported this theory when he reported that one-third of the steller sea lions (eurnetopius jubatus) investigated had 1-10 gastroliths in their stomachs. h e argued that since the sea lion’s teeth are designed for grasping and tearing rather than grinding, the food is swallowed in larger pieces. since much of the sea lion’s food consists of large, heavily-boned species of fish, the grinding activity 0-10 1050 50-100 100-300 of stones in the stomach would be of assistance in the physical maceration of flesh and bones. similarly, harp seal teeth are small and well-fitted for grasping but not for chewing prey. 100 cn 0 80 60 40 e zj 20 z 0 4 0 d l mass of stones (9) fig. 2 . m a s distribution of gastroliths in an adult harp seal. gasfroliths in the harp seal (phoca groenlandica) 337 from the observations of harp seal diet based on stomach content analysis during summer and autumn in northeastern atlantic waters, it appears that the food normally consists of soft bodied crustaceans and small fish, such as capelin mallotus uil~osus and arctic cod boreogadus saida (lydersen et al. 1991; nilssen et a]. 1992a). such a diet is easily digested by harp seals (mhrtensson et al. 1994) and does not require gastroliths to aid digestion. during the seal invasions, however, there was a change in the diet, and heavily boned species of larger fish such as cod, haddock m e l anogramrnus aeglefnus and saithe pollachius uir ens dominated (haug et al. 1991; nilssen et al. 1992b). the present individual had swallowed the fishes whole, as indicated by the presence of otoliths (from the head) and sharp bones (from the head and the rest of the fish) (fig. 1). that harp seals may eat fish of this size (0.3-0.7 kg) in one piece is supported by the fact that captive harp seals have no problem swallowing herring clupea harengus of masses of up to 0.8 kg in one piece (personal observation). a possible expla nation for the presence of gastroliths in the present harp seal may be that the stones were deliberately eaten to aid digestion and the dis solution of the sharp bones when the diet changed to gadoid fishes, such as cod. haug et al. (1991) reported on the stomach content of 369 harp seals caught in gill nets along the coast of norway in 198688. despite the fact that gadoid fishes dominated in the diet of these seals, gastroliths, except for small pebbles acci dentally eaten through the prey, were not observed in any of the stomachs ( k . t. nilssen, personal commun.). during the spring of 1995. however, 84 stomachs of yearling harp seals which were caught in gill nets along the coast of northern norway were examined. of these, one was found to contain 19 stones (total mass = 185 g), the largest being 40g, in addition to otoliths from gadoid fishes (k. t. nilssen, pers. commun.). this supports the observation that harp seals on occasion may deliberately eat stones. the reason for the low occurrence of gastroliths in gill net caught harp seals may be that the stones are voided when the seals struggle in panic to escape from capture. emery (1941), in citing c . r. schroeder, re ported that both captive seals and sea lions have been observed to ingest pebbles from the floor of zoo tanks soon after feeding. these were appar ently later regurgitated after the food had been digested. it is certainly possible that gastroliths also may function to remove difficult digestible hard fish bones from the stomach when the stones are regurgitated. in favour of the latter may be the fact that far fewer backbones and jawbones were found than would be expected from the number of otoliths still present in the harp seal stomach. another function of gastroliths in the stomach, as pointed out by hamilton (1933), is the possible grinding effect on stomach parasites, such as nematodes. harp seals are usually heavily infested with nematodes (personal observation). an alternative, or supplementary, explanation for gastroliths may be that the stones serve to destroy the parasites and reduce the irritation caused by them, thus lessening the degree of infestation. in conclusion, i suggest that harp seals, on occasion may intentionally swallow gastroliths in order to ease the digestion of large prey, and that this phenomenon may represent the marine counterpart to the eating of small stones by many species of wild gallinaceous birds to support the grinding function of the gizzard (schmidt-nielsen 1984). acknowledgemenrs. thanks to k . lindgird for his comments to the manuscript. this study was supported in part by the norwegian fisheries research council. references emery, k . 0. 1941: transportation of rock particles by sea mammals. 1. sediment. petrol. 11, 92-93. gjertz, 1. & wiig, 0. 1992: feeding of walrus odobenus ros marus in svalbard. polar rec. 28, 57-59. harkonen, t. 1989: guide to [he ofoliths of the b o y fishes of the northeast atlantic. danbiu, aps. hellerup, denmark. hamilton, j . e . 1933: the southern sea lion, otaria byronia (de blainville). discovery rep. 8 , 26%318. haug, t . , k r ~ y e r . a . b . , nilssen, k . t . , ugland, k . i . & aspholm, p. e . 1991: harp seal (phoca groenlandica) invasions in norwegian coastal waters: age composition and feeding habits. ices 1. m a r . sci. 48. 36ll371. king, j . e . 1983: seak of the world. oxford: oxford university press. laws, r . m . 1956: the elephant seal (mirounga leonino, linn.) 11. general, social and reproductive behaviour. falkl. isl. depend. suru., lond. scient. rep. 13. 1-88. ling, j . k . & bryden, m . m . 1981: southern elephant seal mirounga leonina linnaeus, 1758. pp. 291-327 in: ridgway, s. h. & harrison, r . j . (eds): handbook of marine m a m m a b . vol. 2 : seals. academic press, london. lydersen, c . , angantyr, l. a , . wiig, 0 & 0ritsland, t. 1991: feeding habits of northeast atlantic harp seals (phoca groen landica) along the summer ice edge of the barents sea. can. 1. zool. 48, 2180-2183. 338 e . s . nordoy kumlien. l. 187y contributions to the natural history of arctic america made in connection with the howgate polar expedition. 1877-78. bull unired srares nanonal museion. no. 1.5. government pnnting office. washington. mathews. l . h . 1929: the natural history of the elephant seal. with notes o n other seals found at south georgia discour? rep. 1 . 23?-256 martensson. p . e , nord0y. e. s. & blix. a. s. 1994: digest ibility of crustaceans and capelin in harp seals ( p h o c o groen landica). mar. mamm sci. 10. 325331. nilssen. k. t . , haug. t . . potelov. v . & timoshenko. y . 1992a: preliminary data on feeding and condition of barents sea harp seals (phoca grornlandicn) throughout the year. ices. cm 19yzjn:s. 23 pp. nilssen. k t . , grotnes. p. e . & haug. t. 1992b: the effect of invading harp seals lphoca groenlandira) on local fish stocks of north norway. fish. res. 13. 2 5 3 7 , bien. n. & bntsland. t. 1991: recaptures of harp seals (phocn groenlandico) tagged as pups in the greenland sea. pup production and dispersion patterns. unpublished paper no. wp sea-33 presented to the joint ices/nafo working group on harp and hooded seals. copenhagen, 14-18 octo her 1991. 21 pp. riedman, m . 1990: the pinnipedr. seals. sea lions, and walruses. university of california press. los angeles. schmidt-nielsen. k. 1984: animal physiology: adaptarion and enuironmenr. cambridge university press, cambridge, uk. sivertsen, e. 1941: on the biology of the harp seal phocn groenlandica erxl. investigations carried out in the white sea 1925-1937. hoalrddets. skr. 26. 1-164. spalding. d. j . 1964: comparative feeding habits of the fur seal. sea lion, and harbour seal o n the british colombia coast. bull. fish. res. board can. 146. 1-52, regulation of annual weight cycles in reindeer and other cervids morten ry g ryg, m. 1983: regulation of annual weight cycles in reindeer and other cervids. polar research 1 n.s., 249-257. seasonal changes in weight, food intake and metabolic rate are characteristic of reindeer and other northern ungulates. this article reviews relationships between endocrine and weight cycles in reindeer and other cervids, and the effect of manipulations with endocrine cycles upon the weight cycle. it appears that the secretions of most endocrine glands change throughout the year, either as a result of nutritional changes or of an inherent seasonal rhythm. it is suggested that the weight and metabolic cycles are secondary to an appetite cycle that is hormonally regulated. the hormonal control may include several hormones: sex steroids, thyroid hormones, and prolactin. morren ryg, zoofysiologisk institutt, postboks 1051 blindern, oslo 3 , norway. introduction it is well known to reindeer herders that the reindeer grow slowly or lose weight in the winter, and gain weight rapidly during summer (skjen neberg 1965). this cyclic pattern is not dependent on the seasonal changes in food quality and avail ability as it occurs also when a standard feed is offered ad libitum throughout the year. the annual weight cycle and accompanying cycles of food intake and metabolic rate seem to be genetic features shared by a number of northern ungu lates including cervids, sheep, muskox, chamois, and one antelope, the saiga (french et al. 1956; mcewan 1968; wandeler & huber 1969; mcewan & whitehead 1970; bandy et al. 1970; mcewan 1975; knorre 1961; abaturov et al. 1982). these cycles are probably adaptations, partly to seasonal fluctuations in food quality and quantity, and partly to the strains of reproduction. the physiological regulation of the weight cycle is not well known. in this paper, the possible significance of endocrine factors is discussed. becaux our knowledge of the reindeer is often scant or lacking, i shall also draw on results obtained using other cervid species. characteristics of the annual cycle dependence on age and sex with adequate nutrition, fawns of all cervid species grow uninterrupted from birth, usually in may or june, to october-november when weight gain declines. weight changes during the winter are dependent on nutrition (see p. 250) and on the weight of the fawn at the beginning of the winter. with adequate nutrition a small fawn can gain more weight than a large one. blaxter et al. (1981) observed that the weight gain of red deer fawns from 3 to 9 months of age was inversely proportional to body weight at weaning. although the data were not presented, the same appears to be true for white-tailed deer (moen 1973:165) and moose (knorre 1961). the weight gain increases in both yearlings and older animals in april or may. in some races of the widely distributed odocoileus hemionus (mule deer and black-tailed deer), a slight weight gain in april or may is often followed by a period of relative constant weight in june and july, and most of the weight gain in the summer occurs after mid summer (bandy et al. 1970). blaxter et al. (1974) noted a regular transient decline in the weight gain of the red deer in june and july. a similar halt, or weight loss, in june and july was also reported by ryg & jacobsen (1982a) in reindeer. because of the regular occurrence of the phenom enon, blaxter et al. (1974) doubted that it was due to excessive heat or insect harassment. a transient halt in the weight gain in midsummer may be a regular occurrence in cervids. it may be physiologically regulated, as it appears from the data of ryg & jacobsen (1982a) that weight changes in midsummer were related to body weight; the larger the initial body weight, the 250 m. r y g greater t h e weight loss (expressed as % of body weight as well as in absolute terms). another halt, or weight loss, occurs during the rutting season. the weight loss of rutting males usually increases with increasing age (french e t al. 1956; knorre 1961; mcewan 1968; nordan e t al. 1968; bandy et al. 1970; ryg & langvatn 1982). as also noted by nordan e t al. (1968) this could be due to the larger body weight of older animals, since the weight loss of 14-year-old reindeer males was related to body weight (ryg & jacobsen 1982a). throughout t h e rest of the winter, the body weight declines most in the older (and heavier) males. it thus appears that weight changes throughout the autumn and winter (beginning with rut in the adults), and possibly also during a short period in the summer are related to t h e weight of the animal. food consumption in animals fed ad libitum follows a pattern consistent with the changes in body weight. food intake is higher in the summer than in the winter, and is especially low during the rutting season. in late summer and autumn. prior to the rut. food intake often reaches peak values, especially in older males. metabolic rates are as much as 40% lower in the winter than in the summer in white-tailed deer (silver et al. 1969) and reindeer (segal 1962; mcewan & whitehead 1970). in roe deer t h e differences were smaller (weiner 1977), and no seasonal differ ences were found in o n e red deer hind fed a maintenance ration throughout the year (brock way & maloiy 1967). skeletal development has been less studied than changes in body weight. knorre (1961) found that shoulder height and shoulder-to-ischium length did not change appreciably between 6 and 12 months of age in moose calves kept in enclo sures with natural vegetation. from studies of caribous shot at different times throughout the year, dauphin6 (1976) found low rates of increase in mandible, metatarsus and total body length, and in shoulder height from december t o may. o n the other hand, in reindeer calves fed ad libitum, ryg & jacobsen (1982a) found that total length and t h e length of t h e lower jaw did nor increase from october t o january, while both total and jaw lengths increased steadily from jan uary onwards. t h e r e was even a tendency to slower growth in the summer than in the winter. a similar pattern was noted in red deer fawns shot at different seasons by mitchell e t al. (1976), and in r o e deer and chamois fawns by wandeler & h u b e r (1969). mean jaw lengths and basilar lengths did not change from october to novem ber. but from february and t h e rest of t h e winter jaw lengths increased. basilar length was prac tically constant in yearling roe deer and chamois from 12 months of age, i.e. from june-july in their second summer of life. effects of nutrition t h e appearance of the growth cycle is dependent o n t h e quality and quantity of available food. nordan e t al. (1968) found no seasonal pattern in o n e white-tailed buck fed 60% of ad libitum intake throughout t h e year for two years. there was n o evident weight loss during the rut, and weight gain continued uninterrupted throughout the winters. t h e lack of weight loss during rut could be d u e to the slow weight gain of this animal in the summer, since weight loss during rut may be size-related (see p. 249). t h e animal with a reduced ration did not reach t h e same weight as the 14-year-old bucks having free access t o food, and thus may not have reached a weight where a loss during the rut normally occurs. food intake and weight changes in animals fed a d libitum depends on the quality of the food. it seems that, in wild and domestic ruminants alike, t h e intake of natural foods is limited by the capacity of the gastrointestinal system and the passage rate of t h e food. in animals with similar physiological status, the voluntary intake of roughage is inversely related t o gastrointestinal turnover (hjeljord e t al. 1982; milne e t al. 1978). t h e turnover rate, in turn, is related to the maturity and degree of lignification of the plants. so, the appetite and weight cycles seen in animals o n standard diets will be accentuated by the sea sonal changes in food quality. also, hypertrophy of the rurnen. which occurs in the summer (staa land et al. 1974; mitchell et al. 1976) would allow a greater intake for a certain turnover rate. in red d e e r , intake of various roughages was greater in the spring than in midwinter, although gas trointestinal turnover did not change systemati cally (milne e t al. 1978). some metabolic control of food intake probably also occurs. during the winter, intake of lichen is higher in free-ranging than in penned reindeer (holleman e t al. 1979), and lactating red d e e r (clutton-brock e t al. 1982) and reindeer (white 1979) spend more time graz ing than non-lactating females. differences in patterns of skeletal development regulation of annual weight cycles in reindeer 251 from a direct correlation between total eating time and total food consumption (arnold 1981). there is also evidence that total grazing time can change in response to increased energy demand or decreased instantaneous intake (see p. 250; white 1979). (see p. 250) could be due to nutrition. ryg & jacobsen (1982a) reported that the total length increased slower during the winter in reindeer calves with restricted ration than in calves fed ad libitum. on the other hand, skeletal growth from october to january was equally retarded in rein deer calves fed ad libitum and with restricted ration, and has been observed in free-ranging as well as captive animals of other species (see p. 250). this growth retardation could be caused by other than nutritional factors. effects of photoperiod cycles of food intake, weight gain, antler growth and reproductive changes in red deer are entrained by photoperiod (pollock 1975). how ever, the cycles need not be entirely determined by photoperiod. goss (1969a, b; 1976) concluded, from studies on antler development in sika deer, that an endogenous circannual rhythm exists that can be entrained by either increasing or decreas ing day lengths. with certain artificial lighting regimes, antler development lost its relation to photoperiod and returned to a more or less 360 days cycle. changing day lengths could affect food intake by an influence on the daily activity pattern. eriksson et al. (1981) reported that feeding activity of reindeer fed ad libitum throughout the year was determined by an interaction between photoperiod and an ultradian activity rhythm. food consumption varied in accordance with the seasonal changes in the activity pattern. thus it is possible that seasonal changes in food con sumption t o some degree is brought about by behavioral changes that are not related to energy requirements or gastrointestinal function. knorre (1961) reported that moose calves gained less weight in excessively warm summers. under such conditions, they were relatively inactive during the day, and did not increase their nightly food intake sufficiently to compensate for the reduced foraging time during the day. however, the annual food intake cycle cannot be explained completely by this effect. some investigations have shown that the food intake is maintained or even increased during the shortening days in the late summer (nordan et al. 1968; mcewan 1975; ryg & jacobsen 1982a, b). even if total feeding time were restrained within an ultradian rhythm, the amountof food taken during each eating period can change, and this may cause deviations endocrine correlates of the annual cycle the gonads a relationship between the weight cycle and gon adal activity has been noted in many investiga tions. the pronounced weight loss in the autumn coincides with rutting behaviour and increasing testosterone levels (mcewan 1975; ryg & jacob sen 1982b). cessation of weight gain in red deer in the autumn was age-dependent; older animals coming into rut earlier also stopped gaining weight earlier than younger animals (ryg & langvatn 1982). the weight loss during rut is also greatest in older animals, although this may be an effect of size rather than age (see p. 250). sex differences are also evident, the weight fluctua tions are less pronounced in females than in males (nordan et al. 1968). in addition, the course of depletion of fat stores is sex specific. dauphine (1976) found that most of the subcutaneous, perirena! and abdominal fat disappeared during the rut in adult male caribou, whereas pregnant females lost most fat during the last half of preg nancy. similar patterns were observed in red deer (mitchell et al. 1976). the relationship between the weight, food intake and reproductive cycles persists when the photoperiod is manipulated (pollock 1975). all these observations suggest an effect of gonadal factors on the weight pattern, or that the neuroendocrine mechanisms regulat ing the reproductive cycle also influence the growth and fattening cycles. the thyroid gland it has been suggested repeatedly that the thyroid gland is involved in the regulation of seasonal changes in the metabolic rate (silver et al. 1969; seal et al. 1972; ringberg et al. 1978). hoffman & robinson (1966) found that the follicular epi thelium of the thyroid of white-tailed deer was higher in the summer than in the winter; similar results were obtained in roe deer (pantic & stosic 1966) and red deer (pantic & stosic 1966; eickhoff 252 m. ryg 1957). in contrast, graain (1942) found no sea sonal variations in the histologcal picture of white-tailed deer shot at intervals throughout the year. biochemically. the rate of thyroxine (t4) secretion has been measured by estimating t4 concentrations in plasma, and disappearance rates of radioactively labelled t4. by this method, yousef & luick (1971) found no significant dif ferences in t4 turnover in caribou between the months january, april, and august. this does not contradict the hisotological observations, since from the histological pictures, the greatest changes in activity occur in may and june. compatible with most of the histologcal find ings, seasonal variations in plasma t4 levels, with highest levels in the early summer, have been reported in captive and free-ranging norwegian reindeer (ringberg et al. 1978; ryg & jacobsen 1982a), in free-ranging svalbard reindeer (ring berg 1979) and in captive moose (ryg 1982). similar seasonal variations were found in white tailed deer by oelschlaeger et al. (1980), but not by bubenik & bubenik (1978), although in the latter investigation, there tended to be a transient increase int4 levels in the spring or early summer. in male red deer. ryg & langvatn (1982) found no consistent seasonal differences in t4 levels. in male and female roe deer, and in one adult male svalbard reindeer, levels were highest in december. but there were transient increases in june or july, and a nadir in september (barth & horn 1980; nilssen & ringberg 1980). also in yearling mainland reindeer, t4 levels tended to rise in the late autumn, after a transient decrease in september (ryg & jacobsen 1982a) thus. although there are considerable variations in the reported seasonal patterns there tend to be two peaks in t4 levels one in the early summer and one in the early winter. some dif ferences could be attributed to the effects of dif ferent nutrition. restricted food intake over long periods depressed t4 levels in reindeer (rye & jacobsen 1982a) and white-tailed deer (seal et al. 1972). t4 levels were lower in march than in august in free-ranging svalbard reindeer, but not in a captive animal fed ad libitum (nilssen & ringberg 1980). on the other hand, ryg & jacobsen (1982a) found that t4 levels in yearling reindeer increased in the spring in animals with a restricted diet, and concluded that changes in t4 levels are at least partly seasonally determined. t4 is much less active than its metabolite triio dothyronine (t3), and possibly t4 is primarily a prohormone for t3 (bernal et al. 1981). seasonal variations in t3 concentrations in plasma, with highest levels in the summer, have been reported in male reindeer (ryg & jacobsen 1982a), red deer (ryg & langvatn 1982), moose (ryg 1982), and white-tailed deer (oelschlaeger et al. 1980). in white-tailed does, highest t3 levels were found in may, but thereafter the levels declined, reach ing minimal values in august (bahnak et al. 1981). ryg & jacobsen (1981. 1982a) found that the seasonal changes in t3 levels could to a large extent be explained by changing food intake. no increase occurred in the spring when food was restricted, and changes in t3 levels could be induced by alterations in food intake. some sup port for this idea was also given by studies on moose (ryg 1982). in contrast, westra & hudson (1981) found that t3 levels in wapiti calves decreased in the spring, although food intake increased. nilssen (pers. comm.) found that short-time fasting depressed t3 levels in svalbard reindeer, but not in mainland norwegian rein deer. i have no explanation for these differences. in addition to the amount of food eaten, food quality can influence the t3 levels. seal et al. (1978) found that t3 levels in white-tailed deer were lowest in animals given a diet with low energy content. finally, it cannot be excluded that in some species, seasonally determined changes in the thyroid secretion rate and t4 levels contribute to the changes in t3 levels, and so anticipate changes in t3 production caused by food quality and quantity. the lowering of the metabolic rate of reindeer in the winter is possibly secondary to the lowering of food intake (nilssen et al. 1982; nilssen pers. comm.). ryg (1983) suggested that the metabolic changes could be mediated by the effect of nutrition on t3 levels. however, nilssen et al. (1982) and nilssen (pers. comm.) found that t3 levels were generally poorly correlated with metabolic rates, and so t3 cannot be the only regulator involved. endocrine pancreas and insulin-like activity seal et al. (1978) reported that the composition of the feed affected insulin levels in white-tailed deer; high energy content of the diet caused increased insulin levels as compared with a medium-energy diet. surprisingly, glucagon was unaffected by either protein or energy content of the diet; possibly effects of handling obscured any nutritional effects. to my knowledge, there are regulation of annual weight cycles in reindeer 253 trophs, but a transient 50% reduction of volume density took place in april and may. consistent with the histological observations, seasonal changes in serum prolactin concentra tions, with highest levels in the summer, have been reported in male white-tailed deer (mirarchi et al. 1978; schulte e t al. 1981a) and red deer (suttie 1980). thus, secretion of prolactin follows roughly the same seasonal pattern as weight and food intake. like the growth cycle, prolactin secretion is controlled by changes in day length (brown et al. 1979), and the increase of prolactin levels in the spring in red deer is not dependent on increased food intake, as it occurs also in animals fed a restricted diet (suttie 1980). these observations suggest that prolactin may be involved in the control of food intake and growth in cervids. this has also been suggested for other ruminants; forbes e t al. (1979) found increased weight gain and prolactin levels in sheep, in response to longer days, whereas growth hor mone, insulin and thyroxine concentrations were unaffected by day length as such. the apparent involution of somatotrophs in the late winter is in strong contrast to measurements of growth hormone in serum. elevated levels of growth hormone in april or may have been reported in white-tailed deer (bubenik et al. 1975), moose (ryg 1982), red deer (ryg & langvatn 1982), norwegian reindeer (ryg & jacobsen 1982a), and svalbard reindeer (ring berg 1979), that is, high growth hormone levels are found in a period when the histological picture indicates low activity. there seems to b e little correlation between growth hormone levels and increased weight gain, since growth hormone levels are mostly low during the summer. n o reports of seasonal changes of insulin o r glu cagon levels in cervids. ringberg e t al. (1978) found that somatomedin levels of free-ranging reindeer were higher in february than in july and august. this was interpreted in t h e light of the insulin-like effects of somatomedin. high levels in winter could pre vent excessive lipolysis, and might be a mech anism for economizing with energy resources. however, this interpretation is complicated by the effect of energy intake on insulin levels (seal et al. 1978). reduced energy intake during winter will possibly depress insulin levels, and it is dif ficult t o predict how t h e total insulin-like activity in plasma will change during the year. sotnato medin stimulates specifically the growth of car tilage and participates in the regulation of skeletal growth (raisz & kream 1981). ryg & jacobsen (1982a) observed that mandible length in yearling reindeer started to increase in january, and that the rate of increase tended t o decline during sum mer. this corresponds fairly well with the higher somatomedin levels in february as compared with july and august. the hypophysis seasonal changes in parameters related to hypo physial activity have been reported in a number of cervid species. hoffman & robinson (1966) reported that the weight of the hypophysis relative to body weight in male white-tailed deer was minimal in january and february, and maximal in may and june. this agrees with what stosic and pantic (1966) and lincoln (1971) found in red deer stags. stosic and pantit also found his tological changes in the hypophysis; acidophilic (secreting growth hormone and prolactin) and basophilic (secreting thyrotropin and gonadotro phins) cells were smaller in the winter than in the summer and contained less granules, indicating less secretory activity. in male mule deer, cyto plasmic and nuclear areas of acidophils were min imal in the winter (nicolls 1971). in contrast to other studies, large nuclear areas were also found in the autumn (21 september t o 20 december). schulte et al. (1980, 1981b), using immunocyto chemical staining to identify prolactin and growth hormone producing cells in white-tailed deer, found that the cellular volume density of prolac totrophs increased in the summer, probably caused by hypertrophy of the cells. there were no seasonal changes in the cytology of somato effects of manipulation with endocrine cycles the hypophyseo-gonadal axis since the reproductive and growth cycles are closely related, under both natural and controlled photoperiods, it would be reasonable to suggest a causal relationship. west & nordan (1976) found that methallibure, a non-steroidal drug sup pressing gonadotrophin secretion, inhibited food intake and weight gain of male black-tailed deer. however, as also observed by the authors, the effect may have been directly on the central mech 254 m . r y g anisms controlling food intake, and not via gon adotrophins and gonadal factors. castration abolished the seasonal cycles of food intake and weight in o n e adult male black-tailed deer (mcewan 1975). in contrast, cyclic patterns were evident in castrated male reindeer (ryg & jacobsen 1972b), red deer (brown et al. 1979), and moose (knorre 1961; ryg 1982). in reindeer. the patterns were modified; the food intake of the castrates was lower than in the intact animals in late summer, and the pronounced weight loss seen in the intact animals from late september to the middle of october did not occur in the castrates. from these data. ryg & jacobsen (1982b) suggested that at least two components may be involved in the control of cyclic weight and food intake in male cervids, one related to testicular activity. and o n e non-gonadal. t h e con tributions of these components may vary between species and age groups. prolactin and thyroid hormones ryg & jacobsen ( 1 9 8 2 ~ ) found that treatment of yearling male reindeer with either thyroid hor mones or prolactin resulted in increased food intake. the effects on body weight were opposite: prolactin caused increased weight gain relative to controls. whereas thyroid hormones caused decreased gain. or weight loss. the results were taken as evidence that prolactin could be an endocrine link between changing day lengths and cyclic weight gain. this agrees with the suggestion of suttie (1980), that increased food intake of red deer in the spring was caused by increasing prolactin levels. however, suttie found a lag of about ten weeks between increasing prolactin and increasing food intake, whereas ryg & jacobsen found that the effect of prolactin treatment was evident two days after the start of the treatment. the pineal glntid the pineal gland is probably involved in the ability to respond to photoperiod. in the seasonally breeding soay ram. the testicles can be brought to repetitively develop and regress in response to alternating 16-week periods of short days (8 h light: 16 h dark) and long days (16 h light: 8 h dark). when the superior cervical ganglion was removed, thereby removing all nervous input to the pineal. t h e animals lost the ability to respond t o changes in photoperiod (lincoln & short 1980). recently, bubenik (1583) reported that mela tonin administration t o white-tailed bucks in t h e early summer advanced the antler, molting and reproductive cycles by several months. o n the other hand, brown e t al. (1978) found that pine alectomy of white-tailed deer did not overtly affect weight. food intake or reproductive cycles during the first year after pinealectomy. however, pinealectomy of o n e juvenile buck delayed the antler and molting cycles. indicating that the pineal is important for the establishment of the first cycle. snyder e t al. (1983) recently reported that pinealectomy of white-tailed bucks delayed antler growth and rubout, and delayed the sea sonal cycles of prolactin and testosterone, but did not abolish any of these cycles. t h e authors sug gested that the piiieal gland synchronizes a circannual rhythm that is generated in another part of the brain. this is similar to what goss (1969a, b , 1976) suggested for the effect of light on the annual cycle of the sika deer (see p . 251). endocrine regulation of the annual cycle summary regulation of food intake involves processing of sensory, gastrointestinal, and metabolic stimuli by the central nervous system. hormonal control could be effectuated on the signals, by affecting gastrointestinal capacity, macromolecule syn thesis, or basal metabolic rate; or on the central processing. for example by altering the central sensitivity to signals. if central sensitivity became extremely low, physiological control would be functionally decoupled and could be replaced by behavioral control, i.e. t h e amount of food eaten would be determined by the rhythm of feeding activity and would be unrelated t o energy require ments. eriksson et al. (1981) presented evidence for a behavioral control of food intake in reindeer. o n the other hand, gastrointestinal and metabolic control of intake is suggested by a number of investigations (see pp. 249-250). possibly the con tributions from t h e different modes of control change during the year. if metabolic control is less strict in the summer, overeating could result in rapid growth in young animals, and fattening in the adults. so, cyclic growth and fattening could both be secondary t o a n appetite cycle. endocrine rhythms possibly related t o the regulation of annual weight cycles in reindeer 255 annual cycle include (1) increased gonadotrophin secretion and gonadal activity towards the end of the growth season; (2) increased plasma levels of growth hormone coinciding with the onset of antler growth, skeletal growth under conditions of restricted food supply, and onset of rapid weight gain; (3) increased plasma levels of prolactin, triiodothyronine and, in some species, thyroxine, coinciding with the period of increased food intake and rapid weight gain. triiodothyronine is primarily controlled by nutrition, whereas the other endocrine rhythms are, at least partly, sea sonally determined. in red deer kept with arti ficially changing photoperiod with natural ampli tude but six-month period, changes in food intake and weight could not be explained by changes in the plasma levels of any single hormone (brown et al. 1979). this agrees with the suggestion that hormonal control includes at least two compo nents, one related to gonadal activity, and one non-gonadal. the non-gonadal component could be a complex of hormones including prolactin and, at least in some species, thyroxine. seasonal changes in metabolic rate may be secondary to changes in food consumption, the control being partly mediated through changing triiodothyron ine levels. it remains unknown if thyroxine has functions that are not reflected in the levels of circulating triiodothyronine. the mechanisms controlling the annual endo crine cycles may involve both an endogenous, circannual rhythm, and the interaction of pho toperiod with an endogenous, circadian clock (see p. 251). there may be common elements in the neuroendocrine regulation of the reproductive cycle, the antler cycle, and the cycles of food intake and weight. references abaturov. b. d., holodova, m. v. & subbotin. a . e . 1981: intensivnost potreblenija i perevarimost kormov u sajgakov (sarga rafurica). (intensity of consumption and digestibility of food in saiga ratarica.) zool. zh. 6 1 , 1870-1881. arnold, g. w. 1981: grazing behaviour. pp. 79-104 in morley. f. h . w . ( e d . ) : world animal science 51: grazing animals. elsevier sci. publishing co. amsterdam, oxford, new york. bahnak. b. r . , holland, j . c.. verme, l. j . & ozoga, j . j . 1981: seasonal and nutritional influences on growth hormone and thyroid activity in white-tailed deer (odocoileus uirgi nianus). j . wildl. manage. 45, 104-147. bandy, p. j . , mctaggart cowan. i . & wood, a . j. 1970: comparative growth in four races of black-tailed deer ( o d o corleus hemionus). part i . growth in body weight. can. j . zoo/. 48, 1401-1410. barth, d. & horn. k . 1980: untersuchungen iiber das jahre szyklische verhalten der blutspiegel van thyroxin und harnstoff beim reh (capreolus capreolus). z . jagdwiss. 26, 1-1 1. bernal, j . , obregon, m. j., rodriguez-peria, a , , mallol, j . , hernandez, p . , escobar del rey, f. & morreale de escobar, g. 1981: metabolism and action of thyroid hormones. pp. 107-121 in dumont, j. e . & nunez, i. (eds.): hormones and cell regulation, vol. 5 . elsevier/north holland biomedical press. blaxter, k. l., boyne. a . w . sr hamilton, w. j . 1981: repro duction in farmed red deer. 3. hind growth and mortality. j . agric. sci. camb. 96. 115-128. blaxter, k . l., kay, r. n. b., s h a m a n , g. a . m.. cun ningham. j. m. m. & hamilton. w. j. 1974: farming the red deer. dept. agriculture and fisheries f o r scotland. her majesty’s stationery office, edinburgh. brockway, j . h . & maloiy, g. m. 0. 1976: energy metabolism of the red deer. j . physiol. lond. 194, 22p-24p. brown. r. d . , cowan, r . l. & kavanaugh, j . f. 1978: effect of pinealectomy on seasonal androgen titers, antler growth and feed intake in white-tailed deer. j. anim. sci. 17, 435 440. brown, w . b., forbes, i. m., goodall, e. d.. kay, r . n . b. & simpson, a . m. 1979: effects of photoperiod on food intake, sexual condition and hormone concentrations i n stags and rams. j. physio/. lond. 296, 58 pp, bubenik, g. a . 1983: shift of seasonal cycle in white-tailed deer by oral administration of melatonin. j. e x p . zoo/. 225, 155-156. bubenik. g. a . & bubenik. a . b. 1978: thyroxine levels in male and female white-tailed deer (odocoileus orrginianus) can. j . physiol. pharmacol. 5 6 , 945-949. bubenik, g . a , , bubenik. a . b . , brown, g . m.. trenkle, a . & wilson, d . i . 1975: growth hormone and cortisol levels in the annual cycle of white-tailed deer (odocoileus uirgi nianus). can. j . physio/. pharmacol. 53, 787-792. clutton-brock, t . h . , iason. g. r.. albon, s. d. & guinness, f. e. 1982: effects of lactatlon on feeding behaviour and habitat use in wild red deer hinds. j. zoo/. lond. 198, 227-236. dauphine, j r . , t. c. 1976: biology of the kaminuriak popu lation of barren-ground caribou. part 4: growth. reproduc tion and energy reserves. can. wildl. seru. rpr. ser. 38, eickhoff, w. 1957: uber das jahreszyklische verhalten der schilddriisen van verschiedenen wildarten. frankf. zeirschr. path. 6 8 , 11-26. eriksson, l.-o., kallqvist, m.-l. &massing, t. 1981: seasonal development of circadian and short-term activity in captive reindeer, rangifer tarandus tarandus l. oecologia, berlin. 48, 64-70. forbes. j. m.. driver, p. m . brown. w. b . , scanes. c. g. & hart, i. c. 1979: the effect of daylength on the growth of lambs. 2. blood concentrations of growth hormone, pro lactin. insulin and thyroxine, and the effect of feeding. anim. prod. 29, 43-51. french, c. e., mcewen, l. c.. magruder, n. d . . ingram, r . h . & swift, r. w. 1956: nutrient requirements for growth and antler development in the white-tailed deer. j. wi/dl. manage. 20. 221-232. goss, r. j. 1969a: photoperiodic control of antler cycles in deer. i . phase shift and frequency changes. j . e x p . zool. 170. 311-324. 1-71. 256 m. ryg goss. r . j . 1969b: photoperiodic control of antler cycles in deer. 11. alterations in amplitude. j . exp. z o o l . 171, 223 234 goss. r. j . 1976: photoperiodic control of antler cycles i n deer. 111. decreasing versus increasing daylengths. 1. exp. zool. 197. 307-312. graflin. a. l. 1942: a study of the thyroid gland in specimens of virginia deer taken at intervals throughout the year. 1. morphol. 70. 21-40. hjeljord. 0 . . sundstd. f. & haagenrud. h. 1982: the nutri tional value of browse to moose. 1. wildl. manage. 46. 333-343. hoffman. r. a . & robinson. p. f. 1966: changes in some endocrine glands of white-tailed deer as affected by season, sex and age. j . mammol. 47. 266280. holleman. d . f . . luick. j . r . & white. r . g . 1979: lichen intake estimates for reindecr/caribou during winter. j . wildl. manage. 43. 192-201. knorre. e . p. 1961: itogi i perspektivy odomahenija losja. 7rudy peeoro-llyhkogo gos. zapou. i x . 5-1 13. lincoln. g . a . 1971: the seasonal reproductive changes i n the red deer stag (cerwus elaphiu). 1. zool. lond. 16.7. 105-123. lincoln. g . a . & short. r . v 1980: seasonal breeding: nature's contraceptive. rec. prog. horm. res. 36. 1-43, mcewan. e . w . 1968: growth and development of the barren-ground caribou 11. postnatal growth rates. can. j. zool 36. 1023-1029 mcewan. e . h . 1975: the adaptive significance of the growth patterns in cenid compared with the other ungulate species. zool. z h . 5 4 . 1221-1232. mcewan. e. h . & whitehead. p. e. 1970: seasonal changes in the energy and nitrogen intake in reindeer and caribou. can. j. zool. 48. 905-913. milne. j a . . macrae. j . c . . spence. a . m. 8: wilson. s . 1978: a comparison of the voluntary intake and digestion of a range of forages d t different times of year by the sheep and the red deer. br j . kutr. 40. 347-357. mirarchi. r. e.. howland. b . e.. scanlon. p f.. kirkpatrick. r . l. & sanford. l. m 1978: seasonal variation in plasma lh. fsh. prolactin. and testosterone concentrations in adult male white-tailed deer. con. 1. 2001. 56. 121-127. mitchell. b . . mccowan. d . 8: nicholson. i a . 1976: annual cycles of body weight and condition in scottish red deer. ceriius elaphlo. .i. zool lond. 180. 107-127. mom. a . n. 1973: wildlife e c o l o g y . a n analytical approach. l v h freeman & co.. san francisco. pp. 1-458. nicolls. k. e . 1971: a light microscopic study of nuclear and cyptoplasmic sizc of the aggregate acidophil population in the hypohysis cerehri. pars distalis. of adult male mule deer, odocoileus hemionus hemionus. relative to seasons of the photoperiod and antler cycles. z . zellforsch. 115, 314-326. nilssen. k . j . & ringberg. t . 1980: seasonal changes in body weight. food intake and thyroxine in free ranging and captive svalbard reindeer. rangifer rarandw platyhynchus. pp. 329-332 in reimers. e.. gaare. e . & skjenneherg, s . (eds.): proc. 2nd international rerndeericaribou symposium. reros. .vorway 1979. direktoratet for vilt og ferskvannsfisk. trondheim nilssen. i<.. sundsfjord. j a . & blix, a . s . 1982: energetics of the high arctic (77-81"nl) svalbard reindeer. fed. proc. 4 1 . 1238 nordan. h . c.. mctaggart cowan. i . & wood. a . j . 1968: nutritional requirements and growth of black-tailed deer. odocoileus hemionus columbianus, in captivity. pp. 8%96 in crawford. m. a . (ed.): comparative nutrition of wild animals. symp. z o o l . soc. lond. 21. oelschlaeger. a , . warren, r . j . . scanlon. p. f . , kirkpatrick, r . l. & gwazdauskas, f. c. 1980: seasonal variation in scrum triiodothyronine (t3) and thyroxine (t4) concentra tions of adult male white-tailed deer. virginia j . sci. 31, 101. pantic. v. & stosic. n. 1966: investigations of the thyroid of deer and roe-bucks. acta anat. 63. 58c-590. pollock. a . m. 1975: seasonal changes in appetite and sexual condition in red deer stags maintained on a six-month photoperiod. j . physiol. l o n d . 244. 95p-96p. raisz, l. g . & kream. b. e . 1981: hormonalcontrolofskeletal growth. ann. r e u . phvsiol. 43, 225-238. ringberg. t. 1979: the spitzbergen reindeer a winter dormant ungulate? acta physiol. scand. 105, 266273. ringberg. t . . jacobsen. e . . ryg, m. & krog, j . 1978: seasonal changes in levels of growth hormone. somatomedin and thy roxine in free-ranging, semidomesticated reindeer (rangifer rarandus rarandus l . ) . c o m p . biochem. physiol. 60a. 123 126. ryg. m. & jacohsen, e . 1981: virkninger av e r n z i n g p i serumnivier a\ thyroxin og triiodoihyronin hos rein (rangifer rarandus rarandus). rangifer 1 . 4-9. ryg. m . & jacobsen. e. 1982a: seasonal changes in growth, feed intake. growth hormone and thyroid hormones in young male reindeer (rangifer rarandus tarandus). can. j . zool. 60. s 2 3 . ryg. m . & jacobsen, e . 1982b: effects of castration on growth and food intake cycles i n young male reindeer (rangifer tarandus rarandus). can. j . zool. 60. 942-945. ryg. m . & jacobsen, e . 1982c: effects of thyroid hormones and prolactin on food intake and weight changes in young male reindeer (rangifer tarandm rarandus). ccn. 1. zool. 60. 1562-1567. ryg. m. & langvatn. r . 1982: seasonal changes in weight gain, growth hormone and thyroid hormones in male red deer (ceruus elaphiu atlanticw). can. j zool. 60. 2577-2581. ryg. m. 1982: seasonal changes in weight gain, growth hormone and thyroid hormones in intact and castrated male moose (alces alces alces). can. j . zool. 60, 2941-2946. ryg. m. 1983: 4dvances in the physiological studies in the reindeerkaribou i n 197682. acra zool. fenn. 175, 77-80. seal. c'. s . . verme. l . j . , ozoga. j . j . & ericson. a . w . 1972: nutritional effects on thyroid activity and blood of white tailed deer. j. m'ildl. manage. 36. 1041-1052. seal. u . s . . verme, l . j . & ozoga. j . j . 1978: dietary protein and energy effects on deer fawn metabolic patterns. j . wildl. manage. 42. 776-190. segal, a. n . 1962: sutoenye i sezonnye izmenenija gazoener gitifeskogo obmena u severnego olenja v svjazi z ekologi feskimi uslovijami susfestvovanija. voprosy ekologii 6 , 129-130. schulte, b. a . , seal, u . s . , plotka, e. d., verme, l. j.. ozoga, j . j . & parsons, j . a . 1980: seasonal changes in prolactin and growth hormone cells in the hypophyses of white-tailed deer ( o d o c o i l e w uirginianus borealis) studied by light micro scopic immunocytochemistry and radioimmunoassay. a m . j . anat. 159. 369-318. schulte, b. a . . seal. u . s . , plotka, e . d., letellier. m. a , , verme. l . j . , ozoga. j . j . & parsons, j . a . 1981a: the effect of pinealectomy on seasonal changes in prolactin secretion in the white-tailed deer (odocoileus uirginianus borealis). endocrinology 108. 173-178. schulte. b. a . seal. u . s . , plotka, e . d . , verme, l . j . , ozoga, regulation of annual weight cycles in reindeer 257 j . j . & parsons, j . a . 1981b: characterization of seasonal changes in prolactin and growth hormone cells in the hypo physes of white-tailed deer (odocoileus uirginianus borealis) by ultrastructural and immunocytochemical techniques. a m . j. anat. 160, 277-284. silver, h . . colovos, n. f., holter, j. b. & hayes, h . h. 1969: fasting metabolism of white-tailed deer. j. wildl. manage. 33. 49c-498. snyder, d . l . , cowan, r. l., hagen, d . r. & schanbacher. b . d . 1983: effect of pinealectomy on seasonal changes in antler growth and concentrations of testosterone and prolac tin in white-tailed deer. biol. reprod. 29, 6 3 7 1 . skjenneberg, s. 1965: rein og reindrift. a s . fjell-nytt, les jaskog. 326 pp. staaland, h., jacobsen, e . & white, r . g. 1979: comparison of the digestive tract in svalbard and norwegian reindeer. arctic alp. res. 11, 457-466. stogie. n. & pantic. v . 1966: cyclic changes in deer pituitary. lugosl. physiol. pharmacol. acta 2 , 231-237. suttie, j . m . 1980: influence of nutrition on growth and sexual maturation of captive red deer stags. pp. 341-349 in reimers, e., gaare, e . & skjenneberg, s. (eds.): proc. 2nd. interna tional reindeericaribou symposium, rciros, norway 1979. direktoratet for vilt og ferskvannsfisk, trondheim. wandeler, a . & huber, w. 1969: gewichtswachstum und jah reszeitliche gewichtschwankungen bei reh und gemse. r e u . suisse zool. 76, 686696. weiner, j. 1977: energy metabolism of the roe deer. acta theriol. 2 2 , 3-24. west, n. 0. & nordan, h. c. 1976: hormonal regulation of reproduction and the antler cycle in the male columbian black-tailed deer (odocoileus hemionus columbianus). part 11. the effect of metallibure and hormone treatment. can. westra, r . & hudson, r. j. 1981: digestive function of wapiti calves. j . wildl. manage. 45. 148-155. white, r . g. 1979: nutrient acquisition and utilization in arctic herbivores. pp. 1 3 5 0 in underwood, l. s . , tiezen, l. l., callahan, a. b . & folk, g. e. (eds.), comparatiue mech anism of cold adaptation. academic press, new york, london, toronto, sydney, san francisco. yousef, m. k . & luick, j . r . 1971: estimation of thyroxine secretion rate in reindeer, rangifer tarandus: effects of sex, age and season. comp. biochem. physiol. 40a. 789-795. 1. zoo^. 54, 1637-1656. criscuolo.indd 115criscuolo et al. 2001: polar research 20(1), 115–118 brood patch temperature during provocation of incubating common eiders in ny-ålesund, svalbard francois criscuolo, michel gauthier-clerc, yvon le maho & geir w. gabrielsen in this short note we describe the behaviour and body temperature changes of three incubating female common eiders (somateria mollissima) during provocation made by humans approaching the nest. the study site was near the settlement of ny-ålesund, svalbard. temperature transmitters were implanted subcutaneously at the brood patch and data recorded using a vhf receiver. we found that the female eiders in the experiment exhibited a passive defence response (“freezing”), accompanied by a significant drop in brood patch temperature (0.6 °c) during provocation; this temperature drop lasted for 5 minutes. these results accord with other studies of the physiological changes which accompany the passive defence response in birds and other animals. f. criscuolo, m. gauthier-clerc & y. le maho, centre d‘ecologie et physiologie energetiques, cnrs, 23 rue becquerel, 67087 strasbourg cedex 2; g. w. gabrielsen, norwegian polar institute, polar environmental centre, n-9296 tromsø, norway. environmental stressors, such as approaching predators, induce physiological changes in birds, mammals and other animals. autonomic responses must enhance the physiological and behavioural ability of the animal to cope with these events (harvey et al. 1984). in wild birds, two types of behavioural responses have been described: the active and the passive defence responses. the former involves the activation of the sympathetic nervous system, which induces the “fight-or-flight” response. the animal reacts actively against the stressor, preparing itself either to confront the threat or to escape (gabrielsen & smith 1995). the physiological changes which accompany the active defence response include increased heart rate and respiration, redistribution of the blood flow to the skeletal muscles, enhanced glycemia and higher body temperature (siegel 1980; culik et al. 1990; gabrielsen & smith 1995). in contrast, other birds show a passive defence response in which the animal crouches or freezes (gabrielsen, blix et al. 1985). this behaviour is particularly suited to incubating birds, which, by remaining motionless on the nest, enhance their chances of being undetected by predators (gabrielsen 1984; steen et al. 1988). the physiological aspects of the passive defence response include reduced skeletal blood flow and lowered heart rate and respiration (which lessens the body odour emitted, hindering detection by a predator) (gabrielsen & smith 1995). in a previous study of incubating female common eiders (somateria mollissima) in svalbard, gabrielsen (1984) found that both females nesting close to the settlement of ny-ålesund and those nesting in dense colonies on small islands in the area showed the passive (“freezing”) defence response. however, the physiological changes accompanying this behavioural response showed some interesting differences between the birds nesting in the settlement vs. the island colonies (see discussion in gabrielsen 1984). research note 116 brood patch temperature during provocation of incubating common eiders although respiration and heart rate data have been recorded during provocation of incubating common eiders in svalbard, less is known about the effect on body temperature of incubating eiders. in this paper we describe the changes in body temperature, measured at the brood patch, during human provocation of incubating female eiders breeding in svalbard. in this species, maintaining a constant nest temperature is of especially important because the high arctic is a harsh environment in which eggs can cool rapidly, and frequent reheating of eggs is energetically demanding for a bird fasting during the 24 26 day incubation (korschgen 1977; gabrielsen, mehlum et al. 1991). after arriving at the svalbard breeding site in mid-april, the female lays a clutch of 4 6 eggs, which it then incubates alone. during this period, the female relies entirely on its body reserves for its energy needs, losing 30 40 % of its initial body mass (korschgen 1977; parker & holm 1990; gabrielsen, mehlum et al. 1991; criscuolo et al. unpubl. data). this fasting strategy enables the female eider to maintain a high level of nest attendance (melhum 1991; criscuolo et al. unpubl. data), which reduces egg predation—mainly from gulls (larus hyperboreus). materials and methods the fieldwork was carried out in ny-ålesund (78°55 n), on the western coast of spitsbergen. in june 1999, three female eiders nesting close to the settlement were caught on the nest and transported to the norwegian polar institute laboratory (less than 150 m away). during the females’ absence from the nest, the eggs were covered with down and grass to avoid nest predation and egg cooling (egg temperatures were not measured during the study). the eiders were anaesthetized with isofluorane-enriched o2. temperature transmitters (txh 2 radio tag 148 mhz, televilt international) were implanted subcutaneously in the brood patch, the defeathered abdominal area which functions to warm eggs. the birds were transported back to the nest, still under anaesthesia, 100 120 min after being captured. the birds were placed on the nest and awoke from the anaesthesia while sitting on the eggs. behavioural observations of the incubating eiders were done from behind a hide, ca. 50 m away from the nest. body temperature was recorded (± 0.1 °c) every 5 10 sec by a vhf receiver placed 100 m away from the nest site. after implantation we did not observe nest desertion. however, one female eider lost her eggs two days after implantation. the two other females incubated until hatching. only one female was recaptured at the end of the experiment and its thermistor retrieved under anesthesia. the defence response was provoked by the approach of a human, walking slowly toward the female on the nest. the person stayed two m away from the bird for 7 min (including the approach period) and then left the area. the birds were never flushed from their nests. the provocation experiment was carried out twice a day—morning and evening. each bird was provoked by humans seven times (n = 7). brood patch temperature was measured: 1) before the experiment, as the mean brood patch temperature during the two minutes before human provocation; 2) during provocation, as the mean brood patch temperature during the 7 min of human presence; and 3) after the provocation, as the mean brood patch temperature recorded for an additional 5 min following the researcher’s withdrawal from the breeding area. this study was approved by the norwegian animal research authority, the ethical committee of the institut français pour la recherche et la technologie polaires, the norwegian polar institute and the governor of svalbard. fig. 1. effect of the approach of a human towards the nest on body temperature of incubating female eiders. after 7 min of provocation the stress experiment stopped (t7) and the temperature of the bird was recorded for an additional 5 min (t7 to t12). this experiment was repeated 7 times on three female eiders. body temperature at t7 was significatively different from the initial and final body temperatures. 117criscuolo et al. 2001: polar research 20(1), 115–118 statistical analysis was carried using an anova for repeated measurements, followed by post-anova tukey tests. values are means ± s.e. results upon provocation there was an immediate cessation of all outwardly discernible body movement. in a characteristic freezing posture, the head was held against the body and eyes were open. the birds remained motionless on the nest during the entire 7 min provocation. the mean brood patch temperature during normal (undisturbed) incubation for the three birds was 39.7 ± 0.1 °c (n = 7), 41.0 ± 0.2 °c (n = 7) and 39.2 ± 0.1 °c (n = 7). average values for all three birds before the experiment was 40.0 ± 0.2 °c (range 39.2 42.0 °c, n = 21). during the provocation experiment, the brood patch temperature of each incubating female changed significantly (anova, f = 13.87, p < 0.0001; fig. 1). after 7 min of human provocation, the brood patch temperature decreased to 39.4 ± 0.2 °c (range 38.5 41.4 °c, tukey test, n = 21, t = -4.99, p < 0.0001). five min after the end of the stress experiment, the birds recovered a brood patch temperature of 39.9 ± 0.2 °c, comparable to the initial value (range 39.1 41.7 °c, tukey test, n = 21, t = -1.038, p = 0.55). an example of the temperature changes is illustrated in fig. 2. discussion as found in a previous study (gabrielsen 1984), incubating female eiders nesting close to a human settlement show the passive defence response (freezing) when provoked by humans. the drop in eider brood patch temperature observed in this study is probably related to the activation of the parasympathetic nervous system and a reduction in blood flow to the skeletal muscles (gabrielsen & smith 1995). the passive behavioural response is also found in willow ptarmigan (lagopus lagopus) in norway (steen et al. 1988) and in svalbard ptarmigan (lagopus mutus hyperboreus) (gabrielsen, blix et al. 1985). ground-nesting birds typically crouch to the ground and freeze, relying on their cryptic colouration and reduced respiration to remain undetected. in opossum (didelphis marsupialis) and deer mice (peromysus maniculatus), the passive defense response is accompanied by a drop in body temperature: a 0.6 °c drop in body temperature among opossum (gabrielsen & smith 1985) and a several degree drop in deer mice (rosenmann & morrison 1974). brood patch temperature measurements obtained in this study are well within the values obtained by rahn et al. (1983) and gabrielsen, mehlum et al. (1991) from female eiders. gabrielsen, mehlum et al. measured a body temperature of 40.1 °c in non-incubating females. rahn et al. measured the body temperature in the proventriculus part of the intestine after capture on the nest (39.1 ± 0.4 °c), as well as the external brood patch temperature with a thermistor implanted in an artificial egg (38.5 ± 0.6 °c). it is interesting to compare the active defence response of penguins with the passive defence response of incubating eiders. when provoked, incubating adélie (pygoscelis adeliae) and gentoo penguins (p. papua) and moulting emperor penguins (aptenodytes forsteri) show increased heart rate (culik et al. 1990; nimon, schroter & stonehouse 1995; nimon, schroter & oxenham 1996) and a rise of 0.8 °c in stomach temperature (regel & pütz 1997). for these large, conspicuous birds, freezing is not an appropriate strategy against predators. in contrast, motionless, cryptically coloured eiders can be undectectable to predators, even from a few meters (pers. obs.). moreover, penguins are better able to defend their nests against predators (handrich, pers. comm.) than are female eiders, e.g. against arctic fox (alopex lagopus) (ferens 1962): staying motionless is the fig.2. typical profile of brood patch temperature in an incubating female eider during provocation. the duration of the presence of a human close to the nest is indicated by the black line. 118 brood patch temperature during provocation of incubating common eiders more appropriate response for eiders. staying on the nest is also the most adaptive response in the context of the harsh environment of svalbard. the ambient temperature in the study area during the incubation period (4 6 °c) is well below the optimal incubation temperature for the eggs (35 40 °c; webb 1987); eggs cool markedly in the absence of an incubating parent. in greater snow geese (anser caerulescens atlantica), birds nesting in the high arctic and which only leave the nest for 25 min (2 8 recesses per day), the egg temperature decreased by 2.8 °c on average (poussart et al. 2000). similarly, a drop of 4.2 °c was recorded in spectacled eider (somateria fisheri) for a recess duration of 37 min (flint & grand 1999). incubating common eiders do not take recesses exceeding 10 15 min and always cover their eggs with down before leaving the nest, thus minimizing their cooling rate (mehlum 1991; criscuolo et al. unpubl. data). with a mean value of 39.6 °c, common eiders show one of the highest brood patch temperatures of incubating birds (drent 1975). the brood patch temperature drop which this study has shown to occur during provocation by a “predator” could have negative effects for eider eggs, but cooling is much more precipitous if the female actually leaves the nest, especially if it is unable to cover its eggs with down first. moreover, reheating of the clutch after temporary nest desertion also has an energetic cost, even more deleterious for a bird which fasts for the duration of the incubation period. acknowledgements.—the financial support for the present work was provided by the institut français pour la recherche et la technologie polaires, the norwegian polar institute and the european community (funding to ny-ålesund as a large scale facility ). the authors want to thank halvar lundvigsen and moskal wojtek for their help and kindness during the work in ny-ålesund. references culik, b., adelung, d. & woakes, a. j. 1990: the effect of disturbance on the heart rate and behaviour of adélie penguins (pygoscelis adelia) during the breeding season. in k. r. kerry & g. hempel (eds.): antarctic ecosystems. ecological change and conservation. pp. 177–182. heidelberg: springer. drent, r. h. 1975: incubation. in d. s. farner & king, j. r. (eds) . avian biology. vol. 5. pp 333–420. new york: academic press. ferens, b. 1962: notes on the behaviour and activity of birds during the polar day in the arctic. proc. zool. 6, 137–158. flint, p. l. & grand, j. b. 1999: incubation behavior of spectacled eiders on the yukon—kuskokwim delta, alaska. condor 101, 413–416. gabrielsen, w. g. 1984: do not disturb nesting eiders! nor. polarinst. årb., 21–24. gabrielsen, w. g., blix, a. s. & ursin, h. 1985: orienting and freezing responses in incubating ptarmigan hens. physiol. behav. 34, 925–934. gabrielsen, g. w., mehlum, f., karlsen, h. e., andresen, ø. & parker, h. 1991: energy cost during incubation and thermoregulation in female common eider (somateria mollissima). nor. polarinst. skr. 195, 51–62. gabrielsen, g. w. & smith, e. n. 1985: physiological responses associated with feigned death in the american opossum. acta phys. scand. 123, 393–398. gabrielsen, w. g. & smith, e. n. 1995: physiological responses of wildlife to disturbance. in r. l. knight & k. gutzmiller (eds.): wildlife and recreationists: coexistence through management and research. page 95–107. washington, d.c.: island press. harvey, s., phillips, j. g., rees, a. & hall, t. r. 1984: stress and adrenal function. j. exp. zool. 232, 633–645. korschgen, c. e. 1977: breeding stress of female eiders in maine. j. wild. manage. 41, 360–373. mehlum, f. 1991: egg predation in a breeding colony of the common eider somateria mollissima in kongsfjorden, svalbard. nor. polarinst. skr. 195, 37–45. nimon, a. j., schroter, r. c. & oxenham, r. k. c. 1996: artificial eggs: measuring heart rate and effects of disturbance in nesting penguins. physiol. behav. 60, 1–4. nimon, a. j., schroter, r. c. & stonehouse, b. 1995: heart rate of disturbed penguins. nature 374, 415. parker, h. & holm, h. 1990: patterns of nutrient and energy expenditure in female common eiders nesting in the arctic. auk 107, 660–668. poussart, c., larochelle, j. & gauthier, g. 2000: the thermal regime of eggs during laying and incubation in greater snow geese. condor 102, 292–300. rahn, h., krog, j. & mehlum, f. 1983: microclimate of the nest and egg water loss of the eider somateria mollissima and other waterfowl in spitzbergen. polar res. 1, 171–183. regel, j. & pütz, k. 1997: effect of human disturbance on body temperature and energy expenditure in penguins. polar biol. 18, 246–253. rosenmann, m. & p. morrison. 1974: physiological characteristics of the alarm reaction in deer mouse. phys. zool. 47, 230–241. siegel, h. s. 1980: physiological stress in birds. bioscience 30, 529–534. steen, j. b., gabrielsen, g. w. & kanwisher, w. 1988: physiological aspects of freezing behaviour in willow ptarmigan hens. acta physiol. scand. 134, 299–304. webb, d. r. 1987: thermal tolerance of avian embryos: a review. condor 89, 874–898. 22_2_405 22_2_406 22_2_407 22_2_408 22_2_409 lateand postglacial environments in the northern barents sea west of franz josef land leonid polyak and a n d e r s solheim polyak, l. & solheim, a. 1994: lateand postglacial environments in the northern barents sea west of franz josef land. polar research 13(2), 197-207. a lithological and micropaleontological study of three sediment cores from the western franz josef land area, two of them ams “c dated, provides new data on the environmental evolution of the northern barents sea during and after the last deglaciation. glacimarine conditions commenced in the deep franz victoria trough by 13 kyr bp. and then presumably propagated into adjacent inter-island channels of franz josef land. pulses of atlantic-derived water occurred during deglaciation and could have accelerated ice-sheet decay. normal marine environments were established close to 10 kyr b p . ameliorated conditions are recorded for the interval of approximately 9.5 to 5 kyr bp. after that, more severe environments existed probably associated with heavier sea-ice cover. l . polyak, v n l l okeangeologia, st. petersburg. russia; present address: byrd polar research center, the ohio state university. columbus, oh 43210, u . s . a . ; a . solheim, norwegian polar lmtitute, p. 0. box 5072, majorstua. n-0301 oslo, norway. introduction despite extensive studies of the barents sea during the last two decades, there are major gaps in the understanding of the glacial and postglacial history of the region. the most widely studied areas are the western (e.g. e l v e r h ~ i et al. 1990; saettem et al. 1992) and southern (vorren et al. 1989; gataullin et al. 1993) parts of the barents sea. results from these areas show that most, if not all, of the barents sea was covered by an ice sheet during the last glaciation. there are indications of repeated glaciations through the quaternary, which have eroded most of the barents sea shelf surface down to mesozoic strata (vorren et al. 1989; saettem et al. 1992). however, the mode and timing of glaciation and deglaciation processes are still poorly understood. the northeastern part of the barents sea, the least accessible due to ice conditions, is the least investigated. this area, including the franz josef land archipelago (fig. l ) , could have been an important drainage basin for the barents sea ice sheet. furthermore, the adjacent deep franz victoria trough and, saint anna trough are the main gateways for the water and ice exchange between the barents sea and the arctic ocean. intensive investigations on franz josef land were performed in the 1950s by russian geologists, including studies of bottom sediments in the straits (dibner et al. 1959). sediment coring in the area surrounding the archipelago was pur sued by vnii okeangeologia in the 1970s, and the results were presented in technical reports (e.g. kirillov et al. 1979). foraminifera1 inves tigation of selected cores was performed by polyak (1982, 1985). however, these studies lack reliable chronostratigraphic framework. we have chosen three sediment cores from the okeangeologia collection for more detailed, ams 14c time-constrained lithological and for aminiferal examination. in combination with other recent research efforts in the same region (lubinsky et al. 1994; forman et al. in press; lubinsky et al. unpubl.) these results will allow the reconstruction of deglacial and holocene environments of the marine area around franz josef land. physiographic features western franz josef land encompasses two large islands, alexandra and george land, which are separated by cambridge strait (fig. 1). the latter includes a silled basin with depth exceeding 500 m. the northern parts of the islands are pres ently ice-covered. west of the islands the large franz victoria trough with depths of 500-600 m opens t o the arctic ocean. franz josef land is composed of sedimentary 198 l . polyak and a . solheim 36 o 42 48 o 54 o 60 o fig. 1. locations and stratigraphy of the investigated cores. the three main lithological units shown are olive grey hioturbated mud, grey laminated mud, and diamicton (from top to bottom). the positions of ams “c dates are also indicated. and igneous rocks mainly of mesozoic age (dibner 1957). the igneous component distin guishes the archipelago from the surrounding barents sea shelf. the study area is located within the fluctuation zone of the pack-ice margin and is characterised by the multilayer hydrological structure of the arctic ocean (gorshkov 1983; treshnikov 1985). the upper layer of arctic water moves in a southwesterly direction and has low temperatures and salinities (mostly <o”c and <32.5%). in franz victoria trough it is underlain by atlantic derived water, defined by oceanic salinity (>34.5%) and positive temperatures. this atlantic water moves from fram strait along the northern slope of the arctic eurasian shelf, and penetrates the marginal troughs. the core of atlantic water in franz victoria trough lies at 200 to 400 m. it is possible that some portion of atlantic water also flows into the trough from the southwest. below the atlantic layer, franz victoria trough is filled with saline and cold deep arctic water which originates from the norwegian-greenland sea, and dense “winter” water which cascades from the shelf along the marginal troughs (midttun 1985). atlantic water typically does not penetrate the straits of franz josef land and the water column consists of the surface arctic water and cold, saline local bottom water (matishov et al. 1992). materials and methods the piston cores used in this study were collected by vnii okeangeologia in 1977 (stations 32 and 45) and 1979 (station 20) from the hydrographical core 32 is from the deep silled basin in the cam bridge strait. cores 20 and 45 are from the southern part of f r a u victoria trough (table 1; fig. 1). the core material was dried, stored, and vessels ivan kireev and pavel bashmakov. lateand postglacial environments in the northern barents sea 199 table 1 . core locations. core no. area lat. n long. e depth (m) 32 20 45 cambridge str. 80"4 1.07' 47"43' 360 franz victoria tr. 7y22 3 6 ' 39o43.24' 321 franz victoria tr. 7 9 0 5 8 . ~ ' 41'56.9' 365 sampled several times over a period of fifteen years. the results of previous lithological studies, including heavy mineral investigations were com piled by kirillov et al. (1979). additional sedi mentological analyses of cores 32 and 45 were performed during this study at the norwegian polar institute. the sampling covered the lower part of the core 45 section, and most of core 32. the grain size distribution was analysed by wet sieving of the >63 micron fractions, while the fine fractions were optically analysed in a sedigraph. x-ray diffraction analyses (xrd) were carried out on the bulk <63 micron fraction and on the clay fraction. the analyses were undertaken on a phillips pw1700 diffractometer with standard procedures of heating and ethyleneglycol treat ment. semi-quantitative calculations were done using a method described by karlsson et al. (1978). previous foraminiferal investigation of the cores is described by polyak (1982, 1985). additional sampling of core 32 was undertaken in 1992. samples were soaked, wet sieved (0.1 mm), and concentrated by inorganic heavy liquid (kj + cdj) withspecificgravity 1.8 g/cm3. ingen eral, the number of calcareous microfossils in the 1992 samples is less than that of the previous studies, probably due to dissolution and/or dis integration during storage. this process does not table 2. ams "c dates. seem to affect the percentage of foraminiferal species, allowing us to combine previous and recent results. ams i4c dating (fig. 1; table 2) was performed at the swedberg laboratory, university of uppsala, sweden on four samples of calcareous foraminiferal tests from cores 32 and 45; an additional sample from core 32 was dated in the lawrence livermore laboratory, u.s.a. the north atlantic marine reservoir correction of 440 years (mangerud & gulliksen 1975) was subtracted from the laboratory-reported, '3c-normalised age. results lithology the studied cores have similar lithostratigraphies, and resemble cores described by dibner et al. (1959). there are three main lithostratigraphic units (fig. 1). the lower unit is composed of unstratified dark-grey stiff diamicton, identical to glacigenic diamictons described elsewhere from the barents sea (e.g. elverhoi & solheim 1983; szttem et al. 1992; gataullin et al. 1993). the middle unit consists mainly of light-grey soft lami nated mud/clay. the lamination is caused by alternation of clayey and silty bands 1-20 mm core depth in no. core. cm material sample age weight, corr., 14-c lab. ref mg years no. 32 3 a 4 i mixed forams 5.30 4 6 0 0 s 100 tua-180 32 172-174 i .norcrossi/helenae 9.10 9295 -t 110 tua-181 32 244-248 mixed forams 4.00 9990 5 95 tua-182 45 91-97 mixed forams 4.65 13,245 s 150 tua-183 32 150-152 i.norcrossi/ 4.10 10,150 -c 70 cams-5561 helenae, n.labrador. 200 l . polyak and a . solheim cm 285 290 laminated mud diamicton fig. 2. thin-section of the contact between diamicton and laminated mud in core 32. thick. this type of lithofacies is characteristic of proximal glacimarine environments and results from rhythmical changes in the tidewater glacier melting regime and abscence of bioturbation (e.g. e l v e r h ~ i et al. 1983; powell 1983; mackiewich et al. 1984; gorlich 1986). a photo of a thin section (fig. 2) shows a distinct contact between the diamicton and the laminated clay in the cam bridge strait. the upper unit is olive-grey bio turbated mud, iron stained and somewhat sandy in its lower part. this type of sediment is typical for holocene marine environments of the barents sea (elverhgi & solheim 1983; spiridonov et al. 1992). both core 45 from the franz victoria trough and core 32 from the cambridge strait show distinct changes in grain size distribution and clay mineralogy at the boundaries between diamicton, laminated clay and olive grey mud (fig. 3). the diamicton appears homogeneous with little vari ation in grain size distribution. in both cores the sand and gravel contents drop to minimal values on transition from diamicton to deglacial sedi ments, increasing slightly in the overlying olive grey mud with a maximum in its lower part. the silt and clay contents, however, seem to show more diverse trends. in the cambridge strait the clay content increases to a maximum in the deglacial sediments before it drops to post glacial levels, which are roughly similar to those of the diamicton. the clay peak is accompanied by a silt low, while the overlying olive grey mud yields the highest silt content. in franz victoria trough, on the other hand, the silt content increases in the laminated mud, while the clay content drops. there are no detailed analyses in the upper half of this unit, nor in the above postglacial part. these lithostratigraphic changes are also reflected in the mineralogy (fig. 3). in core 32, the transition from diamicton to laminated mud shows a decrease in smectite content followed by a sharp increase. ‘the subsequent peak cor responds t o the clay maximum in laminated mud, while the upper unit is marked by further increase in the smectite concentration. the chlorite con tent (based on the 14a peak only) also slightly rises through the laminated mud to the postglacial level. the remaining clay minerals have their highest contents in the diamicton and eventually drop t o lower postglacial values. in the franz victoria trough (core 43, smectite drops to zero at the transition from the diamicton t o laminated mud, and chlorite appears t o drop. heavy minerals of the fine sand fraction (kirillov et al. 1979) are dominated by either pyroxenes or clastic, originally authigenic min erals (mainly pyrite). pyroxenes, typical for the franz josef land mineralogical province (dibner 1957; klenova 1960) have the highest con centrations in postglacial sediments of the cam bridge strait and decrease both down-section and towards the franz victoria trough. in contrast, pyrite and other “authigenic” minerals, charac teristic of the mesozoic sedimentary bedrock of the central and northwestern barents sea (yashin et al. 1985; e l v e r h ~ i et al. 1988), have their maxi mum content in the franz victoria trough dia micton. paleontology the samples, particularly those from the upper lithological unit (olive-grey muds), generally con tain rich assemblages of calcareous benthic fora minifers with smaller amounts of planktonic forms, and several ostracodes and molluscs (figs. 4 and 5). arenaceous foraminifers are practically absent, which is typical for subsurface sediments of the arctic shelf and probably results from disintegration during early diagenesis (0stby & nagy 1982; spiridonov et al. 1992). additional damage due to dry storage is highly probable. the foraminifera1 content in the diamicton is low, rarely exceeding 1-2/g of dry sediment. the lateand postglacial environments in the northern barents sea 201 grain size (%) clay minerals (%) heavy minerals (%) core 32 0 20 40 60 80 1 0 0 0 20 40 60 80 1000 20 40 60 80 100 8 c q . ~ 3.0 c 8 4.0 5.0 core 45 0.0 h e q) 1.0 .& 2.0 r, r 3 . 0 y s gravel 1 sand i silt i clay wc i llliie i chlorite i ir i smectite pvroxenes i "authigenics" i others fig. 3. grain-sire and mineralogical contents in cores 32 and 45. the lithological columns indicate homogenous mud, laminated mud. and diamicton (from top to bottom). assemblage is dominated by the most common quaternary arctic species (see faunal reference list, p. 207) elphidium excauatum forma clauatum and cassidulina renifornie, and includes "exotic" taxa of more warm-water and older faunas. the preservation varies, and some of the tests display signs of abrasion and recrystallisation. t h e same assemblage is recognized in glacigenic diamicts throughout the barents sea, and is considered to be reworked from older marine deposits (hald & vorren 1987; hald et al. 1990; spiridonov et al. 1992). t h e laminated mud is practically unfossiliferous in the cambridge strait, but contains intervals with relatively high foraminiferal abundance (up to 6s/g of dry sediment) in the franz victoria trough. most detailed study of the lower part of laminated mud in core 45 (fig. 5 ) shows that these abundance spikes a r e separated by foraminiferal barren intervals. t h e lowermost assemblage is dominated by e. e. clauatum and is followed by c . renijornie and/or cassidulina teretis assemblages, the latter being sometimes associated with an increase in planktonic abundance. t h e foraminiferal assemblages in the upper most olive-grey mud are more diverse. in the cambridge strait basin (fig. 4) they are mostly dominated by lslandiella norcrossilhelenae or e. e . clauaturn. in the franz victoria trough cores (fig. 5 ) the dominant species is c . reniforme. in the middle part of all the sections there is a pronounced abundance maximum of melonis barleeanus. and the tops a r e characterised by an increase in the e. e. clauatum content. age control ams i4c dating was performed on well-preserved foraminiferal tests >150 prn picked from their abundance spikes, and supposed to be in situ. 202 l . polyak and a . solheim 4 % benthics b %planktonics e.excavatum njabrador. c.reniforme m.barleeanus 0 1 0 2 0 3 0 0 2 0 4 0 6 0 0 40 0 40 80 0 20 400 40 800 40 80 bcflg 81 fig. 4. distribution of foraminifers in core 32 vs. age in i4c years. the triangles indicate dated levels. bcf/g-number of benthic calcareous foraminifers per gram of dry sediment. the legend for lithology is explained in fig. 3 . the three uppsala dates of the postglacial olive grey mud in core 32 form an orderly succession, while an additional date obtained later at the livermore laboratory gave an age 1 ka too old relative to the other dates. n o signs of reworking to explain this ‘old’ date were found in that part of the core. such a discrepancy cannot be under stood without additional dating. available dates of gravity core tops from the eastern barents sea sediment basins have modern age (polyak et al. in press; forman pers. comm.), and we assume similar age for the top of core 32. together with the three uppsala dates this forms a basis of an age model for core 32, obtained by linear interpolation (fig. 4). discussion deglaciation record the date from the base of laminated mud in the franz victoria trough (core 45; fig. 1) suggests that deglaciation of the trough occurred roughly at 13 kyr bp. a similar date was obtained from a franz victoria trough core in deeper water t o the north (lubinski et al. unpubl.). the accumu lation of laminated mud is likely to have been controlled by glacier melting. the small thickness of laminated mud and absence of apparent brown coloration indicate restricted meltwater influence, which is in contrast t o the southeastern barents sea record (polyak et al. in press). this implies fast deglaciation, probably due to a sea level controlled ice break-up and subsequent calving (jones & keigwin 1988; e l v e r h ~ i et al. 1990). at the same time, light oxygen isotope values in planktonic foraminifers from the franz victoria trough laminated muds indicate reduced salinity of surface water due to local ice-sheet melting (lubinski et al. unpubl.). the mineral composition of the diamictons indicates glacial transportation of the eroded bed lateand postglacial environments in the northern barents sea 203 4 % benthics b e.excavatum c.reniforme c.teretis m.barleeanus i.norcrossi %planktonics bcfig 0 20 40 600 50 1mx) 40 800 40 800 10 200 20 400 40 80 0 10 200 20 400 40 800 20 400 20 400 10 200 20 40 -0.4 u 8 i 0 . 8 1.2 8 fig. 5. distribution of foraminifers in cores 20 and 45 vs. depth in core. the crosses indicate foraminifcral-barren intervals in core 45. the legend for lithology is explained in fig. 3 . rock material from the northwestern barents sea to the franz victoria trough and even to t h e franz josef land straits. this suggests that the main center of glaciation in the northern barents sea was located west of franz josef land, which is consistent with the glacioisostatic rebound pat tern (forman et al. in press). the transition to glacimarine and marine environments increased the role of franz josef land as a minerogenic source for the northern barents sea; this is reflected in the high pyroxene concentr-t' ions. the benthic foraminifera1 assemblage from the bottom of laminated mud (core 45) is charac terized by low diversity and the strong dominance of elphidium excavatum forma clavatum, which is common in glacimarine deposits proximal to a retreating glacier (osterman 1982; hald et al. 1993). successive assemblages in laminated muds are mainly dominated by cassidulina reniforme, a second most important species in glacimarine environments (osterman 1982; vilks et al. 1989; steinsund et a]. unpubl.). foraminifera] spikes, with high contents of cassidulina reretis and occasional planktonic foraminifers, suggest the periodic inflow of atlantic-derived subsurface waters which could have promoted ice melting. recent distribution of c. reretis and planktonics on the eurasian arctic shelf is confined t o areas influenced by atlantic-derived water (khusid & polyak 1989; steinsund et al. unpubl.). the transition from laminated clay to homo genous olive-gray mud in the cambridge strait reflects a major ice retreat within the island limits and is dated t o approximately 10 kyr bp (figs. 1 and 4). assuming that the ice sheet break-up was bathymetrically controlled, we infer a similar time for the glacimarine-marine transition in the franz victoria trough; this is confirmed with dates from the core to the north (lubinski et al. unpubl.). deglaciation of inter-island channels in central franz josef land, as well as in eastern svalbard, is estimated to take place roughly at the same 204 l. polyak and a. solheim time (solheim 1991; landvik et al. 1992; forman et al. in press). postglacial environments the early holocene in the cambridge strait (core 32) is characterized by relatively high sedi mentation rates of 1 mm/yr, as found elsewhere in the eastern barents sea (polyak et al. in press; forman pers. comm.). a likely reason for this is residual glacier melting on the islands and/or redeposition of glacigenic material from the shal low areas due to glacioisostatic rebound (c.f. elverhd et al. 1989; spiridonov et al. 1992). up section sedimentation rates decrease to 0.1 mm/ yr. such low values are typical for recent barents sea environments with the exception of areas, proximal to actively melting glaciers ( e l v e r h ~ i et al. 1989; polyak et al. 1994). the high content of smectite in the postglacial mud of the cambridge strait is typical for hol ocene sediments of the northern barents sea, in contrast to underlying glacial diamictons ( e l v e r b i et al. 1989). its presence seems to be associated with the sediment transport by sea-ice from the siberian shelf via the arctic ocean (stein et al. 1994a). the pioneering foraminiferal assemblage in the cambridge strait at 10 to 9.5 kyr bp is dominated by elphidium excaoatum forma clavatum. this species is known to be highly opportunistic, thriv ing in stressed environments such as low and fluctuating temperatures and salinities, high tur bidity, and short-term productivity period (mudie et al. 1984; hald et al. 1993). the present dis tribution of e. e . claoatum in the barents sea is mainly connected with the polar water and appears to be associated with sea-ice cover (khusid & polyak 1989; hald et al. 1993; steinsund et al. unpubl.). early holocene foraminiferal assemblages in franz victoria trough (core 20; fig. 5) are mostly dominated by cassidulina reniforme, a common species in distal glacimarine and cold water marine soft-bottom environments (oster man 1982; mudie et al. 1984; hald & vorren 1987; steinsund et al. unpubl.). its prevalence in the early holocene is typical for the franz josef land surroundings (c.f. lubinski et al. 1994), and is also reported elsewhere from northwestern and eastern areas of the barents sea (0stby & nagy 1982; spiridonov et al. 1992). the interval of 8.5-9.5 kyr bp in the cambridge strait is characterised by the dominance of lslandiella norcrossilhelenae and nonion lab radoricum, which typically follow e. e . clavatum and c . reniforme assemblages in post glacial sequences and reflect ameliorated environ mental conditions (osterman 1982; vilks et al. 1989; spiridonov et al. 1992). these species pres ently are characteristic of areas with seasonal sea-ice cover and, consequently, high seasonal organic productivity (steinsund et al. unpubl.). n. labradoricum is also known to be a deep in faunal species which feeds on buried organic mat ter (corliss 1991), and is therefore potentially indicative of high-productive environments. the predominance of 1. norcrossilhelenae and n. lab: radoricum coincides with the warmest holocene sea-surface temperatures recorded for svalbard (salvigsen et al. 1992), probably marking a rela tively warm and high-productive period for the franz josef land area. the above species are also abundant ca. 5-7 kyr bp in core 32, accompanied by the peak of melonis barleeanus. the latter is typical for mid-holocene sediments elsewhere in the north ern and eastern barents sea at depths <200m (polyak 1982; spiridonov et al. 1992). highest concentrations of m . barleeanus are reported from fine-grained sediments, typically enriched with organic detritus (corliss 1985, 1991; korsun & polyak 1989). its recent distribution on the arctic shelf is also somehow tied to atlantic derived water (mudie et al. 1984; khusid & polyak 1989), although not necessarily to increased bottom temperatures (steinsund et al. unpubl.). according to diatom data from the norwegian-greenland sea, the strongest atlantic inflow took place at 5-7.5 kyr bp (koc & jansen 1992).,a light oxygen isotope spike obtained from planktonic foraminifers, probably reflecting the maximum warming in the upper water layers, is also observed around 7 kyr bp in the franz vic toria trough and further north in the eurasian basin of the arctic ocean (stein et al. 1994b; lubinski et al. unpubl.). these events correspond to the position of m . barleeanus abundance maxi mum, which might indicate the increase of atlantic influence in the arctic during the mid holocene climatic optimum. late holocene assemblages (after ca. 5 kyr bp in core 32) are dominated by e. e. clauatum, which is a regional pattern for the northeastern barents sea and probably marks the climatic deterioration and expansion of the polar water lateand postglacial environments in the northern barents sea 205 with perennial sea-ice in late holocene (spiridonov et al. 1992; lubinski et al. 1994). relatively high contents of c. tereris and plank tonics in the franz victoria trough at this time indicate the advection of the atlantic-derived water as well. thus, we suggest that at approxi mately 5 kyr bp the recent pattern of circulation with the polar water at the surface and the atlan tic layer below was established in the northern barents sea. conclusions the deglaciation of the western franz josef land area commenced at approximately 13 kyr bp in the franz victoria trough and was completed by 10 kyr bp with the establishment of normal marine environments. inflows of atlantic-derived subsurface water into the franz victoria trough likely occurred during deglaciation. the main minerogenic supply for the study area during the glaciation must have been from the northwestern barents sea. presumably due to sub-glacial erosion. glacimarine and marine sedi ments yield larger amount of the local franz josef land mineral component. another important sediment source in the holocene seems to be associated with the sea-ice transport from the siberian shelf through the arctic ocean. the foraminifera1 record indicates that the most favourable marine conditions took place at 9.5 5 kyr bp, with the strongest atlantic influence about 5-7 kyr bp. in the late holocene, after 5 kyr bp, climatic environments deteriorated and the recent oceanographic pattern was developed in the northern barents sea. acknowledgements. this study is part of a collaborative research between norsk polarinstitutt and vnil okeange ologia. sediment cores were collected by o.v. kirillov and n.a. pashukova. the norwegian research council for science and humanities (navf) is acknowledged for financial support under project 440-93/041. the cams-5561 "c date was sup ported by s.l. forman from nsf award dpp-9001471. d. lubinski kindly revised the early version of the manuscript. anders elvcrhai hclped interpreting xkd data. two anony mous reviewers provided constructive critical comments. the editor was most helpful in improving the manuscript. to all these persons and institutions we offer our sincere thanks. this is byrd polar research center contribution no. 949. references corliss. b. h . 1985: microhabitats of benthic foraminifera within deep-sea sediments. nature 314. 435-438. corliss, b. h. 1901: morphology and microhabitat preferences of benthic foraminifera from the northwest atlantic ocean. mar. micropaleontol. 17. 195-236. dibner. v. d. 1957: geological structure of franz josef land. trudy niiga 81 (in russian). dibner, v. d . , kordikov. a. a. & razin, v. k. 1959: first results of the study of bottom deposits in the franz josef land area. lnformacionnyj sbornik n l l g a 15. 42-51 (in russian). elverhdi, a. & solheim. a. 1083: the barents sea ice sheet a sedimentological discussion. polar res. 1 . 2 s 4 2 . elverhdi. a., l ~ n n e . 0. & seland. r. 1983: glaciomarine sedimentation in a modern fjord environment, spitsbergen. polar res. 1 . 127-149. elverhdi. a , . antonsen. p.. flood, s. b.. solheim. a. & vullstad, a . a . 1988: the physical environment. western barents sea. 1 : 1.5oo.ooo: shallow bedrock geology. norsk polarinst. skr. 179 d . 40pp. elverhai, a , . pfirman, s. l., solheim. a . & larssen, b. 1989: glaciomarine sedimentation in epicontinental seas exem plified by the northern barents sea. mar. geol. 85, 225-250. elverhdi. a , , nyland-berg. m.. russwurm. l. & solheim. a. 1990: late weichselian ice recession in the central barents sea. pp. 289-307 in bleil. u. & thiede, j . (eds.): geological history of the polar oceans: arctic versus anfarcfic. kluwer academic publishers. dordrecht. feyling-hanssen. r . w. 1972: the foraminifera elphidium excauafum (terquem) and its variant forms. micropaleonfol. 18. 337-354. feyling-hanssen, r . w. & buzas. m. a . 1976: emendation of cassidulina and lslandiella helenae new species. j . for aminiferal res. 6, 154-158. feyling-hanssen, r. w.. jdrgensen. j . a , . knudsen, k. l. & andersen, a . l. 1971: late quaternary foraminifera from vendsyssel, denmark and sandnes, norway. bull. geol. sac. denmark 2 1 . 67-317. forman, s. l., lubinski. d . . miller. g. h., matishov, g . . snyder, j., myslivets. v. & korsun, s. in press: post-glacial emergence and distribution of late weichselian ice sheet loads in the northern barents and kara seas. russia. geology. gataullin, v. n., polyak. l. v.. epstein, 0. g . & romanyuk, b. f. 1993: glacigenic deposits of the central deep: a key to the late quaternary evolution of the eastern barents sea. boreas 22, 47-58. gorshkov, s. g . (ed.) 1983: world ocean aflas. ool. 3 . arcfic ocean. pergamon press, oxford. 184 pp. gorlich. k. 1986: glacimarinc sedimentation of muds in hornsund fjord. spitshergen. ann. soc. geol. polonica 56, 433-477. hald, m. & vorren. t . 0. 1987: foraminifera1 stratigraphy and environment of late weichselian deposits on the continental shelf off troms. northern norway. mar. micropaleonrol. 12. 129-160. hald, m.. saettem. j . & nesse. e. 1990: middle and late weichselian stratigraphy in shallow drillings from the south western barents sea: fordminiferal, amino acid and radiocar bon evidence. nor,sk geol. tidsskriff 70. 241-257. hald. m.. steinsund, p. i . , dokken. t.. korsun. s . , polyak, l. & aspeli, r . 1993: recent and late quaternary dis tribution of elphidium excaoatum f . clauafa in arctic seas. cushman foundation sp. publ. 32. 141-153. jones. g . & keigwin. l. 1988: evidence from fram strait (78"n) for early deglaciation. nature 336. 5 6 5 9 . karlsson, w.. vollset. j., bjdrlykke, k. & jdrgensen, p. 1978: 206 l. polyak and a. solheim changes in mineralogical composition of tertiary clays from north sea wells. deoelopmenfi in sedimentology, 27, 281 289. khusid, t. a. & polyak, l. v. 1989: biogeography of benthic foraminifers in the arctic ocean. pp. 42-50 in barash, m. s. (ed.): neogenooaya i chetoertichnaya paleookeanologiya p o mikropaleontologicheskim dannym (neogene and quat ernary paleoceanology based on micropaleontological data). nauka, moscow (in russian). kirillov, 0. v., kuleshova, 0. n. & rozhdestvenskaya, i. 1. 1979: rezul’taty poputnyh morskih geologo-geomorfol ogicheskih issledovanij na shel’fe arkticheskih morej (results of marine geological and geomorphological studies on the arctic continental shelf). technical report, npo sevmor geologia, leningrad. 259 pp. (in russian). klenova, m. v. 1960: geologiya barentwoa morya (geology of the barents sea). izdatel’stvo akademii nauk sssr, moscow. 367 pp. (in russian). koc karpuz, n., and jansen, e. 1992, a high-resolution diatom record of the last deglaciation from the se norwegian sea: documentation of rapid climatic changes: paleoceanography 7, 4w520. korsun, s. a. & polyak. l. v. 1989: distribution of benthic foraminifera1 morphogroups in the barents sea. oceanology landvik, j. y., hansen, a,, kelly, m., salvigsen, o . , slettemark. 0. & stubdrup, 0. p. 1992: the last deglaciation and glacimarine/marine sedimentation on barentseya and edge0ya. eastern svalhard. lundqua report 3 5 . 61-83. loeblich, a. r. & tappan, h. 1953: studies of arctic fora minifera. smithsonion m i x . collection 121, 150 pp. lubinski, d.. korsun, s., forman, s., miller, g., and matishov, g. 1994: was there a holocene marine optimum in franz josef land, northeastern barents sea? 24th arctic workshop abstracts, boulder, p. 52-54. mackensen, a. & hald, m. 1988: cassidulina terelis tappan and c. laeuigata d’orbigny: their modern and late quaternary distribution in northern seas. j . foraminiferal res. 28, 16 24. mackiewicz, n. e.. powell, r. d., carlson, p. r. & molnia, b. f. 1984: interlaminated ice-proximal glacimarine sedi ments i n muir inlet, alaska. mar. geol. 57, 11s-147. mangerud, j. & gulliksen, s. 1975: apparent radiocarbon age of recent marine shells from norway, spitshergen and arctic canada. quatern. res. 5 , 263-273. matishov, g. g., matishov. d. g . , & shaban, a. y. 1992: novye dannye o roli zheloboo o biookeanologii shel’fa zemli franza-losifa i noooj zemli (new data on the role of troughs in the bio-oceanology of the franz josef land and novaya zemlya shelves). preprint, russian academy of sciences, kola science center, apatity. 46pp. (in russian). midttun, l. 1985: formation of dense bottom water in the barents sea. deep-sea res. 32, 1233-1241. mudie, p. j., keen, c. e., hardy, i. a. & v i s , g. 1984: multivariate analysis and quantitative paleoecology of ben thic foraminifera in surface and late quaternary shelf sedi ments, northern canada. mar. micropaleontol. 8, 283 313. bstby, k. l. & nagy, j . 1982 foraminiferal distribution in the western barents sea, recent and quaternary. polar res. 1 , 53-87. osterman, l. e. 1982: late quaternarv historv of southern (ussr) 29, 8 3 ~ ~ . from frobisher bay. university of colorado, boulder, ph.d. dissertation. 380 pp. polyak, l. v. 1982: the downcore distribution of foraminifers in the sediments of marginal troughs of the barents and kara seas. pp. 19-26 in zarkhidze, v. s . (ed.): snatigrafiya i paleogeografiya pordnego kajnozoya arktiki (stratigraphy and paleogeography of the late cenozoic in the arctic). sevmorgeologia, leningrad (in russian). polyak, l. v. 1985: foraminifers of bottom sediments of the barents and kara sea and their stratigraphic significance. unpubl. dissertation, leningrad (in russian). polyak, l. v., lehman, s. j., gataullin, v. & juu, a. j. t. in press: two-step deglaciation of the southwestern barents sea. geology. powell, r. d. 1983: glacial-marine sedimentation processes and lithofacies of temperate tidewater glaciers, glacier bay, alaska. pp. 185-232 in molnia, b. f. (ed.): glacial-marine sedimentation. plenum press, new york. snettem. j., poole, d. a. r., ellingsen, k. l. & sejrup, h. p. 1992: glacial geology of outer bj0m0yrenna. southwestern barents sea. mar. geol. 103, 15-51. salvigsen, o . , forman, s. l. & miller, g. h. 1992: thermo philous molluscs on svalhard during the holocene and their paleoclimatic implications. polar res. 21, 1-10, sejrup, h. p. & guilbault, j . p. 1980: cassidulina renifome and c. o b m a (foraminifera), taxonomy, distribution, and ecology. sarsia 65, 79-85. solheim, a. 1991: the depositional environment of surging sub-polar tidewater glaciers. norsk polarinst. skr. 194.97 pp. spiridonov, m. a., rybalko, a. ye. & polyak, l. v. 1992: late quaternary stratigraphy and paleogeography of the eastern barents sea off central novaya zemlya. pp. 47-68 in spiridonov, m. a. & rybalko, a. y. (eds.): osadochnyj pokrov glyacial‘nogo shel‘fa seoero-zapadnyh morej rossii (sedimentary cover of glaciated shelf, north-western seas of russia). vsegei, st. petersburg (in russian). stein, r., grobe h. & washner, m. 1994a: organic carbon, carbonate, and clay mineral distributions in eastern central arctic ocean surface sediments. mar. geol. 129, 269-285. stein, r., nam, s.-i., schubert, c., vogt, c., fiitterer, d. & heinemeier, j. 1994b: the last deglaciation event in the eastern central arctic ocean. science 264, 692-696. steinsund. p. i., polyak, l., hald, m., mikhailov, v. & korsund, s. in press: recent distribution of calcareous benthic foraminifera in the barent and kara seas. j . foraminiferal res. treshnikov, a. f . (ed.) 1985: atlas of the arctic. moscow. vilks, g., maclean, b., deonarine, b., currie, c. g. & moran, k. 1989: late quaternary paleoceanography and sedimentary environments in hudson strait. geogr. physique quatern. 43, 161-178. vorren, t. o., hald, m. & thomsen, e. 1984: quaternary sediments and environments on the continental shelf off northern norway. mar. geol. 5 7 , 22%257. vorren, t. o., lebesbye, e., andreassen, k. & larsen, k. b. 1989: glacigenic sediments on a passive continental margin as exemplified by the barents sea. mar. geol. 85, 251-272. yashin, d. s . , mel’nitsky, v. ye. & kirillov, 0. v. 1985: structure and composition of bottom deposits of the barents sea. pp. 101-115 in: geologicheskoe stroenie barentseoo karskoao shel‘fa lgeoloeica1 structure of the barents and 204 pp. i , . i baffin island, canada: a study of foraminifera and sediments kara sea shelf). sevmorgeologia, leningrad (in russian). lateand postglacial environments in the northern barents sea 207 faunal reference list cassidulina reniforme nbrvang cassidulina crassa d'orbigny . feyling-hanssen et al., 1971, pl. 7, figs. 18, 19; 0stby and nagy, 1982, pl. 3, fig. 13. cassidulina reniforme nbrvang: sejrup and guil bault, 1980, fig. 2f-k. cassidulina teretis tappan cassidulina laevigata d'orbigny: @stby and nagy, 1982, pl. 3, fig. 18. cassidulina teretis tappan. mackensen and hald, 1988, pl. 1, figs. 8-15. elphidium excavatum forma clavatum cushman elphidium clauatum cushman. feyling-hanssen et al., 1971, pl. 11, figs. 10-13. elphidium excavatum (terquem) forma clauata cushman. feyling-hanssen, 1972, pls. 1, 2. islandiella helenae feyling-hanssen and buzas islandiella helenae feyling-hanssen and buzas, 1976, text figs. 1-4. islandiella norcrossi (cushman) islandiella norcrossi (cushman). loeblich and tappan, 1953, pl. 24, fig. 2; feyling-hanssen et al., 1971, pl. 8, figs. 1, 2. melonis barleeanus (williamson) nonion barleeanum (williamson). feyling hanssen et al., 1971, pl. 9, figs. 15-18; 0stby and nagy, 1982, pl. 3, fig. 15. nonion zaandamae (van voorthuysen). loeblich and tappan, 1953, pl. 15, figs. 11, 12. nonion labradoricum (dawson) nonion labradoricum (dawson). feyling hanssen et al., 1971, pl. 10, figs. 1 , 2 ; 0stby and nagy, 1982, pl. 3, fig. 17a, b. no job name guest editorial—the 1959 antarctic treaty: reflecting on the 50th anniversary of a landmark agreement doi:10.1111/j.1751-8369.2010.00163.x commemorating a particular anniversary is always an arbitrary affair, an act of whimsy. after all, why acknowledge the 50th anniversary of someone or some event as opposed to the 48th? in terms of birthdays, we tend to celebrate each year as another rite of human passage. however, when it comes to events such as wars and diplomatic encounters, the media and political commentators like more substantial blocks of time: 10th, 25th, 50th, 75th and 100th anniversaries are particularly noteworthy. the year 2009 has proven no different in terms of representing a temporal marker for the 50th anniversary of the signing of the 1959 antarctic treaty. in december 2009 a so-called antarctic treaty summit was held in washington, d.c. to take advantage of not only such a milestone, but also “to highlight lessons learned about international governance ‘with the interests of science and the progress of all mankind’ ” (antarctic treaty summit 2009, emphasis added).por_163 145..149 whereas polar scholars will have been thinking of this particular landmark prior to december 2009, the british antarctic survey website helpfully sought to put the year 1959 into a wider context for a broader readership. 1959. it was the year fidel castro’s army rolled victoriously into havana, cuba. luna 3, the soviet probe, gave humans their first view of the dark side of the moon. in the uk, the first section of the m1 motorway opened and the first mini car rolled off the production line; alaska became the 49th state of the usa and the barbie doll made her debut on the world’s toy stage. fewer people probably know that 1959 also saw the signing of the antarctic treaty, yet this unique international agreement has protected antarctica for the past 50 years. (british antarctic survey 2009) at the same time that the barbie doll and castro transformed child’s play and the cold war, respectively, plans were afoot for a conference designed to find some way forward through a series of political and scientific imbroglios. the 1959 antarctic treaty proved itself to be not only visionary, but also exculpatory (see, for example, the near contemporaneous overviews by hanessian [1960] and hayton [1960]). obstacles what were the obstacles? at the most fundamental level, there was the thorny issue of the ownership of the antarctic continent and surrounding seas. who owns antarctica? between 1908 and 1943, seven claimants pressed claims on approximately three-quarters of the polar continental surface as well as maritime antarctica. notwithstanding an unclaimed sector, argentina, australia, chile, france, norway, new zealand and the uk were an odd collection of bedfellows: a mixture of imperial and post-colonial states from the northern and southern hemispheres (rothwell 2010). some claimants recognized other claimants, but, critically, argentina, chile and the uk did not (dodds 2002, 2008). their three claims substantially overlapped with one another. the usa and the ussr, the new superpowers in the post-1945 era, did not recognize any of those claims. in the run-up to the washington conference, a series of attempts to manage, let alone resolve, this uncertain territorial tapestry of claims, counter-claims and non-claims were moderately successful: the chileans for example advocated territorial suspension, and the us government under president truman played with the idea of condominiums (beck 1986, 2010). the cold war itself was another complicating factor to this territorial uncertainty. by the early 1950s, it was abundantly clear that the antarctic was embedded within this new global strategic matrix. on the one hand, the us navy conducted so-called winter training operations (operations high jump and windmill) in the late 1940s, and on the other, the soviet union made it clear that it was not going to be excluded from any political arrangement to manage the polar continent (toma 1956; gan 2009). any suggestion that the antarctic was removed from cold war calculations is wide of the mark. although it is true that the arctic was by far the more important polar theatre for military–strategic plotting and planning, the antarctic was also subject to cold war anxieties, aspirations and fears. when the ussr discussed their plans to construct research stations in the antarctic in the mid-1950s, australian papers were swift to headline their stories with “reds on the ice”, and to speculate that the soviets might establish secret missile stations, which correspondence klaus dodds, department of geography, royal holloway, university of london, egham, surrey, tw20 oex, uk. e-mail: k.dodds@rhul.ac.uk polar research 29 2010 145–149 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 145 mailto:dodds@rhul.ac.uk might terrorize the unsuspecting australian public, a polar equivalent of nevil shute’s on the beach (dodds 2010). a third issue worth dwelling on was the resource value of antarctica. the 19th and 20th centuries demonstrated that this apparently remote continent and its seas were filled with all kinds of exploitative possibilities. offshore, seals and whales were valuable commodities, harvested and processed on the disputed island of south georgia. onshore, the post-war period ushered in new speculation about the mineral wealth of the continent itself. coal, oil, gas and uranium were just some of the resources mentioned both by military and civilian commentators eager to make the case that the antarctic was an underexploited treasure house (for a critical review see lewis [1963]). as an aside, it is worth noting how submissions pertaining to outer continental shelves in the southern ocean, especially close to the antarctic peninsula region, have resurrected this view of the polar continent (see, for example, merrick [2007]; and for a short academic reflection, see joyner [2010]). finally, we might just ponder upon, in terms of those messy factors, the double-edged nature of science itself. even if science and scientists are often lionized in many accounts of the events and circumstances leading up to the 1959 antarctic treaty, my own view is that we need to be a little more jaundiced. science was, at it best, a mechanism for promoting cooperation and exchange. there are lots of heart-warming stories of personal and professional cooperation between scientists before, during and after the international geophysical year (see belanger 2006). but it could also be used to promote aggressive forms of nationalism and territorial bellicosity. argentina, chile and the uk were locked into a “science war” in the 1940s and 1950s: they mapped, surveyed and evaluated the antarctic peninsula so that they could then turn and announce to their competitors that they had the best maps, surveys and databases of this disputed region (dodds 2008). science and scientists were arguably making a bad situation worse, and were sustaining, albeit unwittingly, political leaders ever eager to celebrate “achievements”. in argentina and chile, and other southern hemispheric countries, such as australia, this mattered. territorial claims were taken very seriously. but it also mattered to the uk—a familiar refrain being that british scientists did “better” science than their south american counterparts. by the time of the 1957–58 international geophysical year (igy), the 12 governments involved in polar research agreed that their scientists needed to be able to operate without restriction (howkins 2008). in other words, every claimant state would have to accept that others, including the two superpowers, would indeed be able to establish research stations, without due regard for existing territorial claims. this was not an easy compromise, and some claimant states such as argentina and australia found it a bitter diplomatic pill to swallow. for the australian government, it meant countenancing the presence of the ussr and their research stations in the australian antarctic territory (aat). in argentina and chile, two countries with intensely developed territorialized public cultures, political leaders reluctantly accepted that the british and others, such as the americans, were entitled to establish new scientific bases in the south american sector of antarctica (at halley bay). the two superpowers, with their respective bases at the south pole (usa) and the pole of relative inaccessibility (ussr) the south pole, 30 october 1961, the year the antarctic treaty came into effect. gordon robin, director of the scott polar research institute, holds the left side of a commemorative plaque and tore gjelsvik, director of the norwegian polar institute, supports the plaque’s other end during a ceremony marking the 50th anniversary of the attainment of the south pole by amundsen and scott, and their parties. rear admiral david m. tyree, commander of us operation deep freeze, is on the far right. (photo courtesy of norwegian polar institute photo library.) guest editorial polar research 29 2010 145–149 © 2010 the author, journal compilation © 2010 blackwell publishing ltd146 were determined to carry out their scientific and political business without too much regard for claimant states and their proclivities. getting to washington the apparent stakes in the antarctic and beyond were not, thereofore, insubstantial. by the time the delegates met in washington, d.c. on 15 october 1959 there were reasons to be cautiously optimistic, but, at the same time, wary of assuming that a treaty, let alone the modus vivendi established under the igy, would transmogrify into something more sustaining. this is important to bear in mind because there is a tendency, both then and now, to assume that the success of the igy was a “magic bullet” (berkman 2010). this would, in my view, and others’, be mistaken (bulkeley 2010). the working arrangements pertaining to the igy, and the political status of the antarctic, worked in part because all participants, including the claimant states, appreciated that they were committing themselves to a period of 18 months. even if the igy was extended beyond its initial period, under the guise of the international geophysical cooperation, this was still an additional year in duration. so, no party was committing itself to anything approaching perpetuity. clearly there were discussions in the preparatory meetings held before the washington conference concerning arrangements in the post-igy epoch. all the interested igy polar parties, initially contacted by the eisenhower government in june 1958, were acutely aware that the igy was not intended to achieve political–territorial closure. when the delegates arrived in washington, d.c. in october 1959, it was clear that some tough negotiating was necessary in order to secure any kind of new agreement over the status of the antarctic. during the conference itself, there were moments of high drama and farce as delegates threatened to walk away from the discussions (dodds 2008). argentina, australia, chile and france were the most dogmatic over their sovereign rights. new zealand was the only claimant to publicly and privately consider the possibility of renouncing their claim to the continent. the uk, desperate to reduce their financial commitment to the region, wanted to find a durable solution that would cement their presence without, if possible, decolonizing another part of the british empire. both the ussr and the usa were eager to protect their position on non-recognition of claims, but at the same time ensure that access was unfettered. for the usa, moreover, the right of inspection was also important within a period of growing suspicion over the intentions of the ussr more generally, following the berlin crisis, the hungarian uprising, the cuban revolution and nuclear testing (berkman 2010). if the treaty emerged to enjoy public scrutiny, it was down to the simple fact that securing some kind of outcome was better than none. the treaty itself, as is well known, contains 14 articles, which declared inter alia the antarctic to be a zone of peace and cooperation where scientific investigation would enjoy unfettered access to the continent. article iv was pivotal, and allowed all parties to agree to disagree over the ownership of the region in question (rothwell 2010). the rights of claimant and non-claimant alike were suspended for the duration of the treaty. the parties established, within the treaty, mechanisms for the future evolution of the treaty (including the option of a revision conference, 30 years after the treaty came into force), and the possibility of expansion of membership to the treaty, subject to certain caveats. the area of application, defined under article vi, applied to the area south of 60°s, including ice shelves, without prejudice to the rights of states within the high seas. the treaty was unquestionably avant-garde, in the sense of establishing the world’s first nuclear-free zone and placing a continental region beyond the preserve of a few sovereign jurisdictions, but it was nearly not ratified in argentina. article xiii declared, “upon the deposit of instruments of ratification by all the signatory states, the present treaty shall enter into force for those states and for states which have deposited instruments of accession”. so, in order to enter into force, argentina as one of the original signatories had to deposit “instruments of accession”. politically, the frondizi government had a torrid time trying to convince skeptical members of the argentine political establishment and media that argentina was not “giving up” its rightful territorial sovereignty (dodds 1997). this was not really surprising given the emphasis placed by the perón administrations in the 1940s and 1950s on securing argentina’s rights in the antarctic and south atlantic. so although the ratification hearings within the us senate heard that the treaty in question was comparable with the magna carta (laurence gould), the public reaction in argentina was rather more lukewarm. some 18 months later, approximately the same duration of the igy itself, the treaty entered into force in june 1961. so, the experiences both before and after the washington conference were varied. whereas the 12 original parties subsequently celebrated their achievements, there were moments of fracture and fissure both in washington, d.c. and then further afield in places like buenos aires and, to a lesser extent, santiago de chile, canberra and paris. in the uk, the build-up to the conference was not unproblematic. desperate to cut costs and mindful of imperial dissolution, the macmillan government discussed the possibility of pulling out of antarctica in 1958, and even again discussed this in the early 1960s. the antarctic treaty actually saved british antarctic guest editorial polar research 29 2010 145–149 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 147 science: although many within government were dismissive of the uk’s territorial claims, they were more willing to be persuaded that science should be carried out in the antarctic because of the intellectual importance of the research itself (dodds 2008). without the treaty, and its commitment to the pursuit of science and international cooperation, the uk could have lost its foothold in the antarctic. finally, we should not forget the contribution of other places: new delhi, india, may not have been a signatory, but its decision to raise the “question of antarctica” in the united nations in 1956 and 1958 should be recalled. at the time it caused diplomatic panic, and served as a timely aide-memoire to the original parties that international interest in antarctica was growing, notably within a state recently decolonized (dodds 2006). looking ahead, we will on the one hand continue to see new research that further complicates our understandings of the 1959 antarctic treaty. irina gan’s interventions, for example, have already shown that russian language sources provide fascinating insights into how the antarctic generated a series of political, economic, diplomatic and ideological engagements and commitments (gan 2009). socialist ideology, as with the arctic, provided a critical resource for which soviet planners understood and justified to domestic and international audiences the goals of their antarctic programme in the 1950s onwards. a recent special feature in the journal signs also reminds us that the antarctic (and the polar regions more generally) can be profitably interrogated via a gendered analysis, especially when one considers how often the antarctic seems to be visualized as a “testing ground” of men and their practices, including ideas (rosner 2009). how would a gendered account of the 1959 washington conference unsettle our received understanding? the historiography associated with the 1959 antarctic treaty will evolve, and be ever more contested, with time. this will come about in part because of new research, but also through changes to the antarctic treaty system more generally, as different actors, issues and organizational challenges shape it. as india and china, for example, have cemented their presence in the antarctic, so a new generation of scholars from these two countries, including the indian political scientist sanjay chaturvedi, will contribute different perspectives on the 1959 antarctic treaty and its aftermath (see, for example, chaturvedi 1996). this will inevitably unsettle the kinds of accounts routinely produced by english-speaking scholars in the usa, uk, australia and new zealand. final thoughts the stories we tell about the 1959 antarctic treaty have changed over the intervening 50 years. what is clear is that the hegemonic narrative attached to the treaty favours particular actors, events and organizations, such as the usa, science and scientists (including the scientific committee on antarctic research) and the igy (1957– 58), respectively. the preamble of the 1959 antarctic treaty reaffirms this particular understanding of how aspirations and circumstances combined fortuitously to transform the political–scientific landscape of the region (see belanger 2006). although there is clearly much to be said for this assessment, it is fundamentally interpretative. one of the interesting things about the diplomatic papers to be found in the archives of the uk, australia and new zealand is the willingness of civil servants and ministers to contemplate a series of counter-factual possibilities in both the run-up to and in the midst of the washington conference. notwithstanding the confidence of many that science was a tool of diplomacy, there is no shortage of archival evidence of officials contemplating a series of different outcomes—including no treaty at all. the antarctic continent could have become a nuclear testing zone during the cold war had the treaty not been secured and subsequently applied. even if we acknowledge the achievements of those responsible for the treaty, we should not lose a sense of how precarious and contingent it all was. a different outcome could have easily emerged, one perhaps we would less readily acknowledge in 2009 when we seek “lessons” (berkman 2009). as the treaty transmogrified into the antarctic treaty system, antarctica itself is represented as a “scientific laboratory”, with a vision being offered to the world featuring orderly and civilized investigations, being carried out by like-minded individuals and groups. by the 1970s and 1980s, this vision of the “scientific laboratory” the south pole, 1974, the year tore gjelsvik was elected president of the scientific committee on antarctic research. flags represent the original 12 signatory nations of the antarctic treaty. (photo o. orheim, courtesy of norwegian polar institute photo library.) guest editorial polar research 29 2010 145–149 © 2010 the author, journal compilation © 2010 blackwell publishing ltd148 and the treaty as a “benign piece of statesmanship [sic]” was being openly challenged. for example, in un debates on antarctica, states such as malaysia were challenging this view of benign, let alone enlightened, policy-making and management: for post-colonial states the treaty was an example (and not the only one at that) of a select group of countries determining the political future of an entire continent, with limited regard and reference for a world where the footprint of empire remained in africa and asia. environmental groups, with their different agendas, also contested attempts by the treaty parties to determine current and future patterns of resource exploitation of the antarctic continent and the southern ocean (beck 1986). thus, the treaty was considered to be indicative of inequality both of access and power: the power to decide, shape and manage. the eventual entry into force of the protocol on environmental protection in 1998, with its prohibition on mining, did a great deal to restore the authority of the antarctic treaty consultative parties. the 1959 antarctic treaty was an extraordinary achievement. my comments here are meant as caveats to those who would uncritically celebrate that achievement. every treaty has its creation myths and the antarctic treaty is no different (bulkeley 2010). it is striking that those commentators who seek to draw “lessons” from the treaty (including advocating the treaty as a blueprint for the contemporary arctic) often do so without really demonstrating any critical appreciation of the shaky circumstances leading up to the washington conference, and its aftermath (see, for example, berkman 2009). buried within those arguments is often a rather naive view of science, unconnected to what senator william fulbright once termed the military–industrial–academic complex (collis & dodds 2008; korsmo 2010). if there are lessons to be learned from the 1959 antarctic treaty, then they have to be contextualized historically, geographically and politically. acknowledgements i would like to thank the organizers of the meeting the antarctic treaty: 50 more years of preserving peace?, held at cumberland lodge, windsor, uk, in june 2009. my research on the antarctic was generously funded by the british academy. references antarctic treaty summit 2009. accessed on the internet at http://www.atsummit50.aq on 25 january 2010. beck p. 1986. the international politics of antarctica. london: croom helm. beck p. 2010. fifty years on: putting the antarctic treaty into the history books. polar record 46, 4–7. belanger d. 2006. deep freeze: the united states, the international geophysical year, and the origins of antarctica’s age of science. boulder: university press of colorado. berkman p. 2009. international spaces promote peace. nature 462, 412–413. berkman p. 2010. common interests in the international space of antarctica. polar record 46, 7–9. british antarctic survey 2009. antarctic treaty 50th anniversary—2009. accessed on the internet at http:// www.antarctica.ac.uk/about_antarctica/geopolitical/treaty/ anniversary.php on 25 january 2010. bulkeley r. 2010. the political origins of the antarctic treaty. polar record 46, 9–11. chaturvedi s. 1996. the polar regions. chichester: john wiley. collis c. & dodds k. 2008. assault on the unknown: the historical and political geographies of the international geophysical year (1957–8). journal of historical geography 34, 555–574. dodds k. 1997. geopolitics in antarctica. chichester: john wiley. dodds k. 2002. pink ice: britain and the south atlantic empire. london: i.b. tauris. dodds k. 2006. post-colonial antarctica: an emerging engagement. polar record 46, 59–70. dodds k. 2008. the great game: britain and the 1959 antarctic treaty. contemporary british history 22, 43–66. dodds k. 2010. assault on the unknown: geopolitics, antarctic science and the international geophysical year (1957–8). in s. naylor & j. ryan (eds.): new spaces of exploration. pp. 148–172. london: i.b. tauris. gan i. 2009. will the russians abandon mirny to the penguins after 1959 . . . or will they stay? polar record 45, 167–175. hanessian j. 1960. the antarctic treaty 1959. international and comparative law quarterly 9, 436–480. hayton r. 1960. the antarctic settlement of 1959. american journal of international law 54, 349–371. howkins a. 2008. reluctant collaborators: argentina and chile in antarctica during the international geophysical year 1957–58. journal of historical geography 34, 596–617. joyner c. 2010. the antarctic treaty and the law of the sea: fifty years on. polar record 46, 14–17. korsmo f. 2010. glaciology, the arctic and the us military, 1945–58. in s. naylor & j. ryan (eds.): new spaces of exploration. pp. 125–147. london: i.b. tauris. lewis r. 1963. antarctic dilemma. bulletin of the atomic scientists 19, 18–21. merrick j. 2007. scramble for antarctica: argentina hits back after britain makes land grab. daily mail, 18 october 2007. accessed on the internet at http://www.dailymail.co.uk/ news/article-488025/scramble-antarctica-argentina-hitsbritain-makes-land-grab.html on 8 april 2010. rosner v. 2009. gender and polar studies: mapping the terrain. signs 34, 489–493. rothwell d. 2010. sovereignty and the antarctic treaty. polar record 46, 17–20. toma a. 1956. soviet attitude towards the acquisition of territorial sovereignty in the antarctic. american journal of international law 50, 611–626. guest editorial polar research 29 2010 145–149 © 2010 the author, journal compilation © 2010 blackwell publishing ltd 149 http://www.atsummit50.aq http://www.antarctica.ac.uk/about_antarctica/geopolitical/treaty http://www.antarctica.ac.uk/about_antarctica/geopolitical/treaty http://www.dailymail.co.uk research note notes on the stratigraphy, extent and tectonic implications of the minkinfjellet basin, middle carboniferous of central spitsbergen winfried k. dallmann dallmann. w. 1993: notes on the stratigraphy. extent and tectonic implications of the minkinfjellet basin, middle carboniferous of central spitshergen. polar research 1 2 4 2 ) . 15.3-160. a part of the carboniferous basin stratigraphy. the elastic to carbonaceous minkinfjellet “member” of the nordcnskioldbreen formation in central spitshergen. is deposited i n an asymmetric basin structure (here referred to as the minkinfjcllet basin). similar to the underlying ebbadalen formation. the westcrn boundary situated within the billefjorden fault zone has prohdhly been a little farther cast than during dcposition of the ebbadalen strata. the thickness attains ca. 350m in central parts of the basin. and the strata strongly attenuates to the east and south. the hase and top are interpreted as low-angle stratigraphical unconformities. the boundary with the overlying cadellfjellet member of the nordcnskioldhreen for mation is locally disrupted by carbonate breccias of suggested earthquakc origin. format!on rank is suggested for the sedimentary succession of the minkinfjellet basin. w . k . l)allinanii. norsk polurinstitutt. middelthuirs gare 29. p . 0. box 5072 majorsruu. n-0301 oslo, norwny. .u 8. -..,..... introduction during recent regional geology mapping in central spitshergen for norsk polarinstitutt (dieksonfjorden map sheet. dallmann et al. in prcp.). i came across some peculiarities within the middle carboniferous strata of the area around northern bil lefjorden. some of these observations are controversial to the previously published stratigraphic frame. especially concerning the distinction of the mainly bashkirian ebbadalen formation and the mainly moscovian minkinfjellet “member” (gee el al. 1953: cutbill & challinor 1965; lauritzen et al. 19x9: johan nessen & steel 1992). furthermore. some stratigraphical. litho logical and geometric observations in the minkinfjellet strata stimulated some thoughts ahout the basin-related dcvelopment of the succession. as time did not permit detailed logging or sampling during this mapping work. i hope that this note will encourage others to consider carrying out a more thorough investigation of this hitherto sparsely described part of the carboniferous of svalbard. stratigraphic confusion (table 1) the term ‘minkinfjellet member” describing the lower part of the nordenskioldhreen formation (moscovian to late car boniferous) was introduced by cutbill & challinor (1965). i t is meant to comprise a succession of sandstones, limestones. carbonate breccias and local evaporitcs, stratigraphically situ ated between the evaporitic ebbadalen formation (“lower gypsiferous series”. gee et al. 1953) and the overlying part of the nordenskioldhreen formation (“cyathophyllum lime stone”. nordenskiold 1875). i t occurs only to the east of the billefjorden fault zone (fig. 1). though approximately coeval strata (seheteligfjellet member. ?tarnkanten formation) are exposed at some distance to the west. the minkinfjellet “member” was earlier named the “passage beds” (wordie 1919). gee et al. (1953) tentatively correlated the passage beds with a multicoloured sandstone-conglomerate succession at thc mountain pyramiden which they named the “pyramiden conglomerates” according to the earlier described ”pyramiden conglomerate formation” (ljutkevit 1937) or “pyramiden formation” (ustriekij 1967) (fig. 2). later strati graphical work by gjelberg & steel (1981), johannessen (1980) and johannessen & steel (1992), however, placed much of the “pyramiden conglomerates” into the ehhadalen formation and explained them as lateral equivalents to the ehbadalen evapo rites. situated in a proximal setting close to the billefjorden fault zone (odellfjellet member of the ebhadalen formation). the stratigraphic relation between the conglomeratic and the evaporatie parts of the ebbadalen formation (tricolorfjellet member) can be observed farther north at the mountains tri colorfjellet and odellfjellet (north of fig. 1 map area). still. on the geological map sheet billefjorden (lauritzen et al. 1989), these conglomerates are grouped with the minkinfjellet “mem her”, unfortunately without discussing the reason. another name, “elsabreen conglomerate beds” was used by cuthill & challinor (1965). these beds were defined at the northern side of pyramiden, but mcan probably the same suc cession as “pyramiden conglomerates”. since cutbill & chal 154 w . k . dallmann table 1 . stratigraphic names used in thc geological literature related t o the discussed succession. cutbill & challinor 1965 nordenskioldbreen formation tyrrelltjellct member cadeufiellet member minkinfjelln member -_ _ anservika beds carronclva beds pyramiden beds elsabreen beds \ 7 ehbadalen formation gee et pi. 1953 p cyathophyllum limestones (wordiekammen limestones of forbes et al 1958) campbellryggen group passage heds johannessen 1980 proposed here johannessen 8: steel 1992 nordenskioldhrren formation nordenski6ldbreen formarion -- tyrrellfiellet member tyrrellfiellet member cadellfiellet member cadellfiella member minkinfielln member minkinfiella formation forkt member anservika member carronelva member ehhadalen formation ebhadalen formation ’\l -od~llfidlet member odellfiellet member 7 tricolortjellet member tricolorfieuet member ehbaelva member elsabreen member lower c ypsiferous series culm linor do not describe but only mention the latter, a distinction cannot be made. i n the top area of the pyramidcn mountain, thc “pyramidcn conglomerates” are ovcrlain by a light-grey sandstone suc cession of approximately 100 m thickness ( e o ~ on fig. z), which in return is ovcrlain by limestoncs o f the nordenskioldbrcen formation (cadellfjcllct member). this sandstone succession has by previous authors (e.g. lauritzen ct al. 1989: johanncssen & steel 1992) been considered as part of the minkinfjellct “member”. according t o my observations. however. these sandstones bend eastward down, where they form the lower part of the eastern slopes of the mountains pyramidcn. mumien and sven brehegda, and where they are overlain by a thin multicoloured succession. the latter is stratigraphically upward followed by thick evaporites with limestone intercalations lithologically very similar to the gypsiferous tricolorfjellet member. except for the presence of the light sandstones, the stratigraphical relations seem thus to be very similar to those at tricolorfjellet (johan ncssen & steel 1992. fig. x), though they are not so easily observed because of strong faulting and downwarping in the petuniahukta area related to both carboniferous and tertiary tectonism (harland et al. 1974). consequently, the light-grey sandstones. both these near the mountain top and those on the slope, arc thought to represent a local facies between the interfingering odellfjcllet and tricolorfjellet members. they are tentatively grouped with the odellfjellct member on fig. 2. i am tending to assume that no minkinfjellet strata exist at all in the pyramidcn area or west of petuniabukta. basin geometry and geographic extent as can be concluded from the above discussion, the fault terminating the minkinfjellet basin stratigraphy t o the west is situated farther east than that of the ebbadalen basin strata. this would be the case whether or not this fault represented the primary basin margin or a post-minkinfjellet/pre-cadellfjellet billetjordrn croup fault uplift to the west that possibly led to erosion of the minkinfjellet strata (figs. 3 and 4). a peculiar feature of the minkinfjellet succession. in simi larity with the ebbadalen strata, is the considerablc change in thickness (see isopachs in fig. 1). close to the fault, at cheopsfjellet, it is about 5 0 m. but increases rapidly to ca. 350 m to the east of petuniabukta. from there. it decreases slowly eastward and southward to thicknesses of a few tens of metres at filchnerfonna and southcrn billefjorden. its continuation t o the north is. unfortunately. not exposed. the angular unconformity above the minkinfjellet succession is very slight and shows overstepping charactcristics. this and the considerable facies variations within the succession (see below) may exclude the idea that the asymmetric geometry of the basin fill could be due to post-minkinfjellct downwarping and erosion. though the strata to the east of petuniabukta is cut by both normal and reverse faults, none of these seem to be of middle to late carboniferous age. reverse faults affect the entirc carboniferous strata (fig. 5 ) and are probably of tertiary age, while most normal faults d o not proceed higher than into the lower carboniferous and are overlain by the undeformed ebbadalen succession. some of thesc normal faults have prob ably been reactivated later (tertiary?), but no deformation structures are uneonformably covered by the cadellfjcllet mem ber of the nordenskioldbreen formation. the asymmetric basin structure in which the minkinfjcllet succession lies is thus much more pronounced than indicated by earlier authors. post-sedimentary tectonics and possible earthquake breccias still, thcrc is evidence for minor faulting soon after the dcpo sition of the minkinfjcllet succession. i n several places at the western sidc of wordiekammen and at fortet. peculiar fissures which arc filled with chaotic brcccias can be observed (figs. 6 and 7). the fissures dissect the base of the cadellfjellet mcmher _ _ f ig . 2 f .. i :>., b o u n d ar y o f gl ac ie r ;-,.+j$$:; 1 m ai n f a u lt s : n o rm al f au lt rever se f au lt unkn o w n t y p e outc ro p o f m in ki nf je ll et s tr at a is o p ac h s: a p p ro x im at e th ic k n es s of '3 0 0 ~ m in ki nf je ll et s tr at a (r n) -. lo m o n o so v f o n n a *:; ,. / ... i / ,' f f c 0 3 fi g. 1 . m ap s ho w in g th e ou tc ro ps o f th e m in ki nf je ll et s tr at a (f ro m g ee e t al . 19 53 , l au ri tz en et a l. 1 98 9, m il os la vs ki j e t al . 19 92 a nd d al lm an n et % al . in p re p. ). t hi ck ne ss es 9 ar e un ce rt ai n so ut h of mi nk in fj el le t/ ca rr on el va 5 an d w es t of t un ab re en . ls op ac hs a re g iv en f or t he 5 . m in ki nf je lle t su cc es si on ' w ith in t he i nv es ti ga te d ar ea . t he f ra m e in di ca te s 3 th e lo ca ti on o f fi g. 2 . in se rt m ap : l oc at io n of i th e ar ea . u l : $ 5 : u l 156 w. k. dallmann fig. 2. the mountain pyramiden with indicated stratigraphic units (e = ebbadalen formation; ee = ebbaelva mcmbcr; e o = odellfjellet member; 0, = red part; o2 = light part; n c = cadellfjellet member of nordcnskioldbreen formation). despite earlier published work, there is probably no min kinfjellet strata in this area. and are uncomformably overlain by a limestone ca. 20-30 m higher up. the strata below has locally suffered minor dis placements. in one place, the uppermost dissected limestones are broken up and a section has been rotated (fig. 6). the breccias consist of adjacent carbonate lithologies. i.e both of the upper minkinfjellet and the lower cadellfjellet carbonate rocks. they are completely consolidated (fig. 7). the most reasonable explanation for these featurcs i can suggest arc earthquakes with related fissurc formation and minor offsets along the latter. stratigraphic subdivision/ nomenclature and facies distribution the base of the minkinfjellet succession is an apparently parallel stratigraphic unconformity; it is defined by a straight, litho logically distinct bed boundary throughout the outcrop area. while both thc minkinfjellet and the underlying ebbadalen succcssions. respectively. are charactcrizcd by lateral facies changes with interfingering of their lithological facies (members). most member boundaries are, at a regional scale, diachronous zig-zag planes arranged obliquely to the formation boundaries (i.e. bases of ebbadalen, minkinfjellet and cad ellfjellet successions). it is thus reasonable to address the minkinfjellet succession as an individual basin sequence and to raise it from a member to a formation rank. like the ebbadalen strata. the minkinfjellet strata have also been deposited in a fault-bounded basin. have a comparable thickness range and a complex lithological variety that needs a subdivision into members. this succession should be excluded from the platform-like deposits of thc nor denskioldbreen formation and be called the minkinfjellef for mation’. though facies transitions occur in eastern areas. wherc the minkinfjellet succession is comparatively thin. cutbill & challinor (1965) subdivided their minkinfjellet “member” into the carronelva, elsabreen, anservika and pyr amiden beds. a s argued above, the pyramiden hcds (not defined by the authors, but probably identical with the “pyramiden conglomerate” of gee et al. 1953) perform the laterally inter fingering westward continuation of the ebbadalen formation (gjelberg & steel 1981; johannessen 1980; johannessen & steel 1992). the elsabreen beds are similarly defined, though in a place a little farther north. the only explanation i can offer after having mapped the area is that these two successions are identical. the carronelva and anservika beds, both defined in places east of billefjorden. have distinct characteristics and should be raised t o member rank. for another distinct lithology that occurs in western parts of the minkinfjellet basin, i would like to propose the name “fortet member”. carronelva member (figs. 5 , 8 and 9). t h e carronelva mcm ber forms the lower part of the minkinfjellet succession in central and northern parts of the basin. it underlies the breccias of the fortet member near petuniabukta and the carbonate rocks of the anservika member. in eastern areas it may consist of only a few metres of red beds or multicoloured clastic rocks (shales, sandstones and conglomerates), either below anservika limestones (make brunfjellet) or as the only representative of the minkinfjellet basin succession (gnomen). at ebbabreen and ragnarhreen the carronelva member also starts with coarse clastic rocks at the base (polymict sedimentary breccias with a carbonate matrix). these basal beds pinch out wcstward where they are replaced by greenish t o yellowish medium-grained sandstones (western half of sfinksen, l ~ v e h o v d e n and wor diekammen). the overlying succession consists of yellowish sandstones, locally with a distinct sulphurous smell. shales, marls, limestones and sandy limestones with gypsum vugs are intercalated in the upper part, where a complex interfingering of lithologies between the anservika and carronelva members occurs. gypsum layers occur in the type locality at carronelva, south of nordenskioldbreen (cutbill & challinor 1965). the thickness at the type locality is 41 m, while it attains more than 100 m in ebbadalen and ragnardalen. anseroika member (figs. 5 , 8 and 9). t h e anservika member consists of dolomites, limestones and fine-graincd limestone conglomerates and occurs mainly in eastern and southern areas, but also in the upper levels of the central and northern basin areas between adolfbukta and terrierfjellet. in places, it com prises most of the basin succession, e.g. anservika, mink infjellet. terrierfjellet, flemingfjellct, make brunfjcllct, though thin clastic beds of the carronelva member may lie below it. the carbonate rocks are interlayered with marls or marly limestones which often give the succession a distinctly stratified appearance. they are more massive and rich in flint concretions or rintstone intcrcalations in the west at pctu niabukta. a few gypsum layers are intercalated in thcir lower * the formal stratigraphic nomenclature of svalbard is recently being elaborated by the committcc on the stratigraphy of svalbard (sks). the revision proposed here has been formally submitted to the committee for consideration. a+ 9 c ro ss s e ct io n ( f ig 3) b o u n d a ry o f g la ci e r m a in f a u lts n o rm a l f a u lt (l o ca l f in a l st ra in ) re ve rs e f a u lt (l o ca l f in a l st ra in ) st ra ta y o u n g e r th a n m in ki n fje lle t f o rm a tio n m in ki n fje lle t "f o rm a tio n " (p ro p o se d r a n k) f o rt e t m e m b e r a n se rv ik a m e m b e r c a rr o n e lv a m e m b e r e b b a d a le n f o rm a tio n t ri co lo rf je lle t m e m b e r o d e llf ie lle t m e m b e r e b b a e lv a m e m b e r strata o ld e r th a n e b b a d a le n f o rm a tio n 5 k m -. e; f f ig . 3 . m e m b e r su b d iv is io n o f th e m in k in fj e ll e t su cc e ss io n s w it h in t h e i n ve st ig a te d i e b b a d a le n a n d 2 ul a re a . 4 158 w. k . dallmann n u a d li u t rd 2 aj g 5 . fig. 5. fault set of probably tertiary age at the northern side of ehhadalen that turns over into a flexure fold within the minkinfjellet succession. et = tricolorfjellet member of ebba dalen formation; mc = carronelva member; ma = anservika member; mf = fortet member; n c = cadellfjellet member of nordcnskioldbreen formation. part at petuniahukta. which rapidly pinch out to the cast. foraminifer faunas have been described by soripatrova ( 1967). while hraehiopods, corals. hryozoans and molluscs havc hcen reported by others (gee et al. 1953; gramherg el al. 1990; dallmann & mi6rk 1991). in addition. i ohserved limestone beds with abundant crinoids on tricolorfjellet. the name-giving section at anservika is 33 rn thick (cutbill & challinor 1965). while it attains 250 to 3ou m on both sidcs of nordenskioldbrccn (terrierfjellet. flemingfjellet). forrer member (figs. 5 and 9). the ahundant appearance of massive carbonate breccias and conglomerates in the upper parts of the minkinfjellet succession at petuniabukta suggests defining these beds as a separate memhcr. the fortet mcmhcr overlies the anservika carbonates (wcstern lcivehovden) o r fig. 6. suggested earthquake breceias at western wor diekammen within the basal limestones of the cadellfjellet member (nordenskioldhreen formation). chaotic intraform ational breeeias f i l l in fissures along syn-sedimentary faults. overlying beds arc undeformed. middle carboniferous of central spitsbergen 159 fig. 8. minkinfjellet strata on the northern side of ragnarbrecn: a basal sedimentary breccia (b) is overlain by a sandstonc dominated succession grading upward into sandstone-limestone alternations ( m c = carronclva memhcr) and overlying limc stones with a few eastward attenuating gypsum beds in its lower part (ma = anservika mcmhcr). nc = cadcllfjellet mcmbcr of nordenskioldbrecn formation. on the southern side of fortet, near rudmoscpynten. arc well suited as a type section for the fortet member. in this place. the thickness is ca. 240 m, which is about the maximum observed fig. 7. suggested carthquakc brcccias at fortet. stratigraphic position as i n fig. 0. the intra[ormation;ll brcccias cut vertically through the strata. thickncss. replaces them (cheopsfjellet, western wordickammen). the brcccias are intraformational and contain unsorted carbonate clasts seldom exceeding diametrcs of iocm. they may locally represent in-situ hrccciatcd bedrock. hut consist of distinctly transported clasts in other places. both grain-supported and matrix-supported varictics occur, with a micritic carbonate matrix. the rocks show different dcgrecs of ccmcntation, so that well-ccmcnted parts tend to forni cliffs and pinaclcs. while thc surrounding material is removed by erosion. the exposures concluding remarks the middle carboniferous minkinfjcllct “member” lies in an asymmetric basin structure with distinctly westward increasing clastic inlux. the succession attenuates towards the south and cast, whcrc carbonate lithologics dominate (the northern con tinuation is not exposed). a rock succession exposed west of bilkfjorden. situated within the billcfjordcn fault zone. has previously been assigned to the minkinfjellet “member” though it most probably forms fig. y. fortet. wuthwestern wordikammen. 10-12 m of dark anservika limestone (ma) between thick successions of the underlying carronclva member (mc). predominantly sandstone and shales) and the overlying fortet member (mf, limestone brcccias). nc = cadellfjellet member of nordenskioldbreen formation. 160 w . k . dallmann part of the underlying ebbadalen formation. minkinfjellct strata do not occur wcst of billefjorden. both the basc and the top of thc minkinfjellet basin strata arc stratigraphic uncon formitics. the subdivision of the minkinfjellet strata is proposed to be extendcd. the minkinfjellet succcssion, formerly defincd as a mcmbcr of the nordcnskioldbreen formation, is proposed to be raised to formation rank due to its individual basin charactcr. similar to thc underlying ebbadalcn formation. few details from the minkinfjellct basin are known. further investigations such as stratigraphical logging, facies analyses and palcon tological age determinations arc nccded in order to understand the development of thc basin. acknowledgements. i would like to express my thanks to e. johannesscn (statoil, stavanger) for critical comments that improvcd thc manuscript. references cuthill. j . l. & challinor. a. 1965: rcvision of the strati graphical schernc for the carboniferous and permian rocks of spitshcrgcn and bjernaya. geol. mag. 102, 418-439. dallmann. w. k. & merk. a. (cds.) 1991: stratigraphical dictionary of svalbard. translation from the russian title: stratigrafifcskij slovar’ spichcrgcna (gramberg, 1. s . , krasil’sfikov. a . a. & scmcvskij, d. v., eds.. 1990). norsk polarinst. rapp. 74. 1-189. forbes. c. l., ilarland, w. 8 . & hughcs. n . f. 1958: palcon tological evidencc for thc age of the carbonifcrous and pcr mian rocks of central vestspitsbergcn. geol. mag. 95, 46% 4yo. gcc. e. r., harland, w. b. & mcwhae, j. r. h . 1953: geology of central vcstspitsbergen. part i: rcvicw of the geology of spitsbcrgcn with spccial rcfcrcncc to ccntral vestspitsbcrgcn. trans. royal soc. edinburgh 52 ( 9 ) , 29y-356. gjclhcrg. j . & steel, r. j . 1981: an outline of lower-middlc carboniferous sedimcntation on svalbard: effects of climatic. tectonic and sea lcvel changes in rift hasin sequences. in kcrr. j . w. & fergusson, a. j.: geology of the north atlantic borderlands. can. soc. petrol. geol. mem. 7. 543-561. gramberg, i . s., krasil’sfikov. a. a. & semcvskij. d. v. (eds.) 1990: stratigrafiteskij slooar’ spicbergena (stratigraphical dic tionary of sualbard). nedra, leningrad. pp. 1-203. hadand, w. b., cutbill, j . l., friend, p. f., gobbett, d. j . , holliday, d. w., maton, p. i . , parker, j . r . & wallis, r. h. 1974: the billefjorden fault zone, spitsbergen the long history of a major tectonic lineament. norsk polarinst. skr. johannessen, e. p. 1980: facies analysis of the ebbadalen formation, middle carboniferous, billefjorden trough. spits bergen. cand. real. thesis, university of bergen. pp. 1-314. johannessen, e. p. & steel, r. j . 1992: mid-carboniferous extension and rift-intill sequences in the billefjorden trough, svalbard. in dallmann, w. k.. andresen, a. & krill, a. (eds.): post-caledonian tectonic evolution of svalbard. norsk geol. tidsskr. 72 ( i ) , 35-18. lauritzen, 0.. salvigsen, 0. & winsnes, t. s. 1989: geological map of svalbard 1:1oo,ooo, sheet cxg billefjorden. norsk polarinst. temakart no. 5 . ljutkevic, e. m. 1937: geologija tretitnich uglenosnych otlo zenij spicbergena rajona ajs-fiorda. (geology of the ter tiary coal-bearing deposits of spitsbergen, lsfjorden area.) n i i g a , trudy 76. miloslavskij, m. ju., birjukov, a . s . , slsnskij, s. n. & dallmann, w. k. 1992: geological map of soalbard i :1oo,ooo. preliminary edition. sheet drg negribreen. norsk polarinstitutt. nordenskiold, a . e. 1875: utkast till lsfjordens och belsounds geologi. geoligiska foreningens i stockholm forhandlingor bd. 2 , 243-260. 301-322, 356373. sosipatrova, g. p. 1967: verchnepaleozojskic foraminifery $pic bergena. (upper paleozoic foraminifers of spitsbergen.) in: materialy po srratigrafii gpicbergena. leningrad. ustrickij, v. i . 1967: osnovynye certy stratigrafii i pale ogeografii vcrchnego paleozoja spicbcrgena. (main strati graphical and palcogcographical features of thc upper paleozoic of spitsbergcn.) in: materialy po stratigrapi $pic bergena. leningrad. wordie, j . m. 1919: report on the carbonijerous exposures north of adolf bay (spitsbergen). scottish spitsbergen syn dicate papers. 161 . 1-72. research note confrontations between humans and polar bears in svalbard ian gjertz a n d e n d r e persen gjertz, i . & persen, e . 1987: confrontations between humans and polar bears in svalbard. polar research 5 n . s . , 2 5 s 2 5 6 . since 1973 there has been a total of 50 serious confrontations between humans and polar bears in svalbard. this paper summarizes these incidents. ian gjertz, norsk polarinstitutt, p . o . box 158, n-1330 oslo lufthaun, norway; endre persen. sysselmannskontoret, 91 70 longyearbyen, norway; april 1987 (revised may 1987). svalbard is the collective name for the group of norwegian islands situated between longitudes 10" and 35"e and between latitudes 74" and 81"n. the islands have a total landmass of about 62,000 km'. national parks and nature reserves occupy 44% of svalbard's land area. svalbard has about 3500 residents, most of whom are employed in the coal mining industry. there are only three towns in svalbard. other settlements are 3 mining camps, 2 scientific stations, 2 manned weather stations and a coastal radio station. there are few trappers in svalbard, usually less than 5. besides the local residents, large numbers of tourists and many scientists visit the islands in the summer season. the norwegian government's highest re presentative is the governor (sysselmannen). he is also the chief of police, and head of nature conservation and wildlife management in the islands. by law all serious incidents of human conflicts with polar bears (ursus maritimus) have to be reported to the governor. polar bears killed in self defence are the property of the state, and such incidents are treated as a police matter. up to 1970, polar bears were hunted in large numbers throughout the islands. in july 1973 polar bears in svalbard were totally protected. since then there has been an increase in the number of polar bears and they are now quite common. according to larsen (1986), bears in east greenland, svalbard and the western soviet arctic all belong to one common discrete popu lation. he estimates that this population in 1970 numbered between 1500 and 2500 bears, and similarly that between 1980 and 1983 it had increased to between 3000 and 5000 bears. the increasing number of bears along with the increase in recreational traffic outside the inhabited areas, should presumably lead to more human contacts with polar bears. the present work summarizes contacts which have led to con flict between man and polar bear since 1973. methods conflicts between humans and polar bears in sval bard can be grouped into three categories: -bears destroying human property. this is quite common. compensations are rarely given, consequently all incidents are not reported. -bears threatening people, dogs or property. in most cases the bears are chased away with no harm being done. occasionally these incidents lead to the bear being shot. -bears killing or injuring people. this is very rare. in the present work the term 'serious con frontation' refers to the two latter categories. data have been obtained from the local news paper svalbardposten, and the governor's files. these files are mainly auction records of skins of bears killed in self defence. little or no biological data on these bears have been recorded. results since july 1973 a total of 50 cases of serious confrontations between humans and polar bears 254 i. gjertz & e. persen no. of bears i i 8 1 i i i i i i 6 1 i i i i i i i i i i 4 1 i i 1 1 i i i i m a a m i 2 1 i m m m n m 1 1 1 1 i i d i i i i i i i i 73/74 75/76 77/78 79/80 8 1 / 8 2 83/84 85/86 74/75 7 6 / 7 7 78/79 ao/ai 82/83 84/85 86/81 winter season fig / serious confrontation5 between humans and polar bears in svalbard sincc july 1973 according t o yearly winter seabons. = 1 confrontation. has been registered (fig. 1). of these cases 46 resulted in the killing of a bear and in one case a bear was wounded. but escaped. in addition three cases with human casualties are known, but in these cases no bears were killed. occurrences related to months (fig. 2) show that most incidents happen in the period decem ber-april. with a small peak in july-august. sites of confronrnrions of the 50 serious confrontations registered. 20 no. of bears 8 1 i i i 6 1 ii i i i d 1 i 4 1 iiii i n ii i i a m l m i i 1 1 1 1 ii a m 2 1 iiiii i d i d i d j f m a m j j a s o n d month fig. 2 . serious confrontations between humans and polar bears since j u l y 1973 according to months of occurrence. = 1 confrontation. occurred at manned field stations. these stations are hopen island (11). bear island (4), hornsund (4) and kapp linne (1). eight of the confrontations occurred in towns and mining camps. in four of these t h e bears were shot in self defence, while the others were shot as precautionary measures. three bears shot in or around longyearbyen were among t h e latter half. eleven polar bears a r e known killed in order to protect property. relatively few serious confrontations, 11 in all, occurred in the field. hitman casualties in only three cases since 1973 have people been injured or killed by bears. in dec. 1975 a man was attacked by a bear in barentsburg. he managed to get away by poking the bear in the eye with his thumb, but received large skin-damages t o the head and was hospitalized. in july 1977 at magdalenafjorden, northwest spitsbergen. a man was killed by a bear when he stepped o u t of his tent. in november 1978 a meteorologist at the polish polar station in hornsund was attacked by a bear. t h e bear bit him in t h e h a n d , but released him and ran when others of the crew started shooting. the man now has a permanent malfunction of the hand. t h e bear was slightly wounded in the upper neck and disappeared. confrontations between humans and polar bears in svalbard 255 occur. this is a problem that is expected to increase in the future. discussion confrontation related to year and month according to fig. 1 there are overall fewer serious confrontations today than in the seventies, in spite of the fact that both the recreational traffic and the number of bears have increased sig nificantly since 1973. this may be because people through the years have learned how to avoid confrontations, which is in contrast to the situa tion in the northwest territories, canada. according to stenhouse (1983), there was an increase in the number of nuisance bears shot in defence of life and property in the decade 1972 1981. on average 15 bears were shot yearly in the first half of the decade as opposed to 28 in the second half. in fig. 1 the year 1982/83 stands out as the exception in an otherwise general decrease in the number of confrontations. of the eight bears killed in 1982/83, four were unnecessary kill ings. two cases resulted in police charges against those who shot. most confrontations occur in the winter. december is the peak month (fig. 2). possibly because people are just as surprised every year when the first bears show up. november and december are often difficult months for hungry bears because there is usually little ice at this time of year, at least on the spitsbergen west coast where almost all of svalbard’s human inhabitants live. bears may therefore come close to settle ments either out of curiosity or in search of food. from january through april there is usually fast ice in the fiords on the spitsbergen west coast and bears are quite common. also, this period partly corresponds with the peak season for out door recreation. these two combined effects make it the period when serious confrontations most frequently occur. of the nine incidents that have occurred in the months of june, july and august (fig. 2), scientists or tourists were involved in seven. four of these cases have happened within the last five years. this may be a result of the steady increase of tourists and scientists visiting svalbard each summer. these people, unlike the locals, visit the remoter parts of svalbard, i.e. the northern and eastern parts, where bears are more common in the summer. many of these scientists and tourists are inexperienced with polar bears and therefore it is more likely that serious confrontations may sites of confrontations serious confrontations occur most frequently at hopen island, which is only inhabited by a four man meteorological crew. l0n0 (1970) showed that the, number of bears at hopen corresponds with the number of days of winter pack ice at the island, and larsen (1986) gives an account of monthly observations of bears at hopen island since 1966. bear island, lying farther south at the edge of the winter pack ice area, has a shorter period of winter pack ice and consequently has fewer bears than hopen island. hornsund has, for a few months every year, large numbers of bears passing through the area on their way to the eastern parts of the archipelago (larsen 1986; gjertz & lydersen 1986). common to all three places is that polar bears, due to winter pack ice conditions, are so numerous for parts of the year that contacts between humans and bears are more common here than in other more populated areas of sval bard. serious confrontations are therefore more likely to occur here than in other places in svalbard, all depending on the experience of the station crews. most of the bears killed as precautionary meas ures were shot in longyearbyen. this may reflect the fact that the governor resides in longyear byen, and it is also the governor who authorizes the killing of bears as precautionary measures. in other settlements local authorities first have to receive the governor’s permission before bears can be shot as precautionary measures. of the eleven bears killed protecting property, two were shot by the same man. he was a trapper protecting his dogfood. these shootings were not considered necessary and the trapper was fined. there may be several reasons why relatively few incidents occur in the field. first of all people are mostly out in the summer and late winter. in the summer bears are scarce in the western inhabitated parts of svalbard, and people visiting the more remote parts of the archipelago usually travel in boats and are therefore relatively safe. in the winter, when bears are numerous in the inhabited areas, people travel by snowmobile and are similarly quite safe. secondly, local people who travel in the wilderness are often used to 256 i . gjertz & e . persen meeting bears and know how to deal with them in a safe way. of the eleven cases of serious confrontations that have occurred in the field, six involved scientists and three tourists. biological data the governor’s files are inadequate, and d o not give much biological information on the bears killed since 1973. however, the available infor mation indicates that many of these bears were young. in the future standard biological data will be collected on all bears killed in self defence in svalbard. references gjertz. i . & lydersen. c . 1986: polar hear predation on ringed seals in the fast-ice of hornsund. svalbard. polar research 4 ( i ) . 6 6 x . larsen. t. 1986: population biology of the polar bear (ursus marifimur) in the svalhard area. n o r s k po[arinrr. s k r . 184. 55 pp. lono. 0. 1970: thc polar bear ( u r . n u maritimus phipps) in the svalbard area. h o r s k p d a r i m r . s k r . 149. 103 pp. stcnhouse. g . 1983: bear detection a n d deterrent study, cape churchill. manitoba. 1y81. n. w . t. w i d . s e r u . fi/e rep. n o . 31. 58 fp. por_034.fm polar research 26 2007 93 – 95 © 2007 the author 93 steiner f r o m t h e c o n f e r e n c e m e l t i n g i c e — a h o t t o p i c ? why “melting ice” as a topic for the world environment day? achim steiner un under secretary-general and executive director, united nations environment programme doi:10.1111/j.1751-8369.2007.00034.x minister, dear friends and colleagues, i already had a chance to address you this morning in the context of the panel. so this afternoon i will be quite brief. i would like to take the opening line that jangunnar winther, director of the norwegian polar institute, just put out: namely that this afternoon we are really focusing more on the science. indeed there is no more appropriate place—a university that was born out of a dream that tromsø would one day bring people from all over the world here to engage and be part of what your principal has called “perhaps the world’s best university”. i hope all of you who study here will be inspired by what you have heard this morning and also by what you are hearing this afternoon from some of the world’s best scientists on climate. world environment day is the united nations environment programme’s (unep’s) special day, but is also a day for the un family as a whole and for and on behalf of people all over the world who care about the environment. we are thankful to you, helen bjørnøy, norwegian minister of the environment, for having made world environment day in norway into a very special week. and for focusing on an issue that is clearly so dear to so many peoples’ hearts and minds, as well as one that is shaping perceptions of development across the globe. for this year’s world environment day slogan—“melting ice: a hot topic”—we did not go to saatchi & saatchi. indeed i am sorry to say to erich roeckner, i do not know who in unep came up with this phrase. but what i do know is that when i was first presented with the slogan it reminded me of when i was with sheila watt cloutier, former president of the inuit circumpolar conference, in montréal in 2005. because, shelia, you also had a slogan at the montréal climate conference two years ago which was equally powerful in its simplicity and message. essentially it said, “we have a right to be cold!”. i was struck at the time by how, sometimes with a simple word or phrase, we can summarize volumes of work into a very simple concept—namely that indigenous people at the climate change convention were making an explicit link between the science of climate change and human rights. in my world, as executive director of the unep, we are increasingly discussing a rights-based approach to development. so when we deal with some of the latest science that is driving development discourse, we should never forget that it is based in a fundamental set of principles that recall the universal declaration of human rights. this declaration should and must remain a fundamental orientation point in how we approach so many issues, climate change included, as they in so many ways define all our roles, including those of the un. ladies and gentlemen, i would like to spend just a few minutes on this question of science because that is the focus this afternoon. environmentalists are, one might muse, some odd breed that biologists have never been able to define in species terms! society and the media have had a go at definitions, often portraying environmentalists from anything to do with leather sandals and muesli to the kinds of einstein-looking figures that sometimes appear at press conferences. indeed it is one of the ironies of the past century that environmentalists—be they ecologists, biologists or zoologists, and often working on low budgets and dealing with imperfect science—have, in trying to open society’s eyes to changes happening on the planet, all too often been subject to the ‘shoot the messenger’ syndrome. that element of uncertainty, that inability to precisely tell society what was the reason and what was the cause, was turned into a blunt almost weapon-like instrument against that message and the messengers. but that situation has changed. one of the most dramatic things that has happened in the last few years is that the environmental community has come of age—has come of age in terms of its capacity and its ability to understand what ecology and environmental change is telling us. indeed many of the hypotheses of the past are becoming scientific reality, with our ability to predict the consequences of our collective actions becoming ever more precise and ever clearer, and the options for changing the outcome—in positive or negative ways—increasingly understood. so science is—and particularly to us in the unep— the most powerful, but also the most fundamental 94 polar research 26 2007 93 – 95 © 2007 the author why “melting ice” as a topic for the world environment day? a. steiner tool for informing the public, and, through the public, policy-makers. but science is not the sole domain of the natural sciences, and one of the themes that i have found myself repeatedly caught up in is the link between the science of what is happening to our natural systems and the other scientific realm of social sciences. ladies and gentlemen, i am an economist by training (but let me stress that i am not an environmental economist. because if you say this it gives the erroneous impression that economics and environmental economics are somehow different disciplines!). but i’ve always believed that understanding natural science—even if you are not a biologist or a zoologist—is part of the responsibility to be able to interpret how the social sciences will guide us in finding solutions. this is why i am delighted that members of the intergovernmental panel on climate change (ipcc) and its chairman, dr pachauri, are here with us this afternoon. for the ipcc is perhaps the culmination of this evolution of trying to bring science to a point where it is not so vulnerable to the ‘shoot the messenger’ syndrome of the past and has evolved to the point at which it can guide society into rethinking its development choices. indeed the ipcc is a remarkable product of incredible effort and meticulous detail. its documents have become unassailable in part because of the impressive effort made to validate a whole community’s work on a global level in a way that is not only unassailable but is unequivocal and ultimately no longer deniable. we have also the challenge today—and this is what the public and the policy-makers often struggle with—that the science is literally exploding from all directions of the planet and from all sorts of disciplines onto the public policy arena. to be a prime minister or to be a minister of environment today is in some ways a nightmare because you are confronted by so many new, fundamental facts for which we do not yet have all the fundamental answers—take the extent to which the greenland ice sheet may or may not melt. and this is where i come back to economics because you do not need perfect science to act perfectly. a few years ago, in germany the government proposed to introduce an eco-tax. it was, i recall, just five cents on a litre of petrol—which has transformed the renewable energy market in germany into one of the most vibrant in the world. it is perhaps forgotten that at the time the greens were accused of essentially ending germany’s economic miracle—the fact that that miracle had ended a few years before was somehow forgotten! at the time, that five cents became a symbol of the incompatibility of intelligent environmental regulatory frameworks and the underlying and politically undeniable fundamental factor of economic growth, jobs and so on. that controversy in germany over five cents has to be set against the backdrop that in the past four years we have lived through a global phenomenon called oil price increases without so much as a wrinkle on global gross domestic production. we have gone from 20 dollars a barrel of oil to almost 72 dollars. now how do you explain to an undergraduate economics student of 1995 that here we are in the year 2007 and we’ve had probably one of the most extraordinary years of economic growth globally? we have had corporations across the globe yielding dividends and profits on an unprecedented level, and we have seen developing countries from china to india, but also mozambique and others, having economic growth rates that were considered in the realm of nirvana just a few years ago—6, 7, 8, 9, 10% per annum. and all this at a time when the price of the “blood” in the cycle of the global economy—the fossil fuel prices— has increased from 20 dollars to over 70 dollars a barrel. it certainly challenges public policy and the kind of economic arguments that claim a shift towards a more sustainable economy will be too costly! the impacts of a simple tax and a creative market instrument, such as the one outlined above, was in full evidence in essen, where i was before coming to tromsø, and where there was a meeting of the european ministers of environment. one study that was presented there was by minister gabriel, the german minister for the environment, nature conservation and nuclear safety. it was a study of employment and green jobs. when the ministry of environment commissioned this study, the minister of economics said, “why are you interfering with economic policy-making? you are the environment minister.” but the study in a sense has informed the public in germany and the government of a simple truth—namely that as a result of public policy and public choices that are emerging, germany’s employment market is undergoing a fundamental restructuring. this restructuring that means that by around 2020 in germany more people will have employment in the sector of environmental technologies than either in the automotive industry or in the engineering industry. now this is something that again, a few years ago, we were told was impossible. yet it was a political choice against the grain of the economic paradigm of the day—a choice that led a government just seven years ago to introduce a tax in germany—not dissimilar to the one that a. steiner why “melting ice” as a topic for the world environment day? polar research 26 2007 93 – 95 © 2007 the author 95 even 15 years ago or 18 years ago you thought about here in norway—a simple tax that was to change the economics of renewable energies in the german economy. it was a tax that essentially forced the energy utilities to buy from any supplier in germany renewable energy— renewable energy produced in your backyard with a solar panel or with a wind power station or a micro-hydro scheme—and to pay a premium for it and to feed it into the grid. in less than six years germany went from being a complete non-actor in the field of wind power to being the world’s largest wind energy producer. ladies and gentlemen, this is not an economic miracle, but a simple lesson in how scientific knowledge translated into public policy choices and then turned into regulatory instruments that empower a market to function differently—and we would say more intelligently— allows the kind of transition to take place that echoes with the issues we are discussing here today. we are not talking about a socialist approach to environmentalism nor are we talking about a capitalist approach to environmentalism. we talking about a transition to a low-carbon economy that allows us to translate the science which tells us what will happen to our planet into economically compatible instruments. and to end my presentation here i would just like to refer to two reports. one is the ice and snow report ( global outlook for ice and snow , unep/grid-arendal, 2007) that some of you will already have heard about today. it is a collaborative piece of work of over 70 scientists which, as i think pål prestrud will tell you more about in a minute, was put through an international peer-review process and compiled with the support of institutions here in norway, including grid-arendal. grid-arendal is, for those who may not be familiar, a very strong partner of unep and one of the support elements that norway provides to our work—namely to keep the global environment under review and to provide the kinds of assessments that open the eyes of policy-makers. the second report, also launched to coincide with world environment day, is the impact of climate change on himalayan glaciers and glacial lakes: case studies on glacial lake outburst floods (glofs) and associated hazards in nepal and bhutan , by bajracharya et al. (2007). unep has produced this together with icimod, the international centre for integrated mountain development in nepal, and it’s another one of these reports that tries to point out a fundamental reality. here we are talking about something called glofs: glacial lake outburst floods. if you want to understand what it means to somebody in bhutan or in nepal to talk about climate change today you need to look at this report. because this is a classic illustration of what it means to be dealing with global warming when you have had nothing to do with the origins of this phenomenon. glacial lake outburst floods are a simple series of chain events: global warming, melting ice building up into new lakes in areas that traditionally would not have stored water, and one day the walls of that lake—the natural containment—will simply give way and within seconds you will have a flood going down a valley at the speed of a modern missile. the reason that i mention this is that the people who are living in bhutan today have established their agriculture and their livelihoods in those valleys over hundreds of years. literally within a decade or two bhutan may have to either invest hundreds of millions in stabilizing these new lakes or move thousands of people somewhere else, because the risk of leaving them downstream of this potential disastrous event is simply something a government cannot do. this is taking the best of science and bringing it into the public policy realm, and also underlining why, when we talk about climate change, we must also talk about an equity dimension—indeed it echoes with the campaign of the inuits in montréal and to the universal declaration of human rights. for a country like bhutan cannot be asked to underwrite the bill of a series of natural phenomena that are unfolding for which it has no responsibility. bhutan can also point quite rightly to another part of the world that, as a result of having used our environment and our natural resources in the way it has, has become wealthy, but as a result has put millions of other people at risk in another part of the world. so i hope that as we look at some of these scientific findings this afternoon, you will get a sense of the challenge but also a sense of optimism and empowerment. that, as we today stand in front of a tv camera or in front of a finance minister or a world bank board, we no longer have to use the kind of hypothetical science that we were dealing with in the 1960s and 1970s, when we were struggling with what we were observing. that we have the power of scientific and empirical evidence combined with the do-ability of an economic pathway that allows us to deliver living standards on an equitable level everywhere and on a par with what we enjoy here in europe. and that this can also be achieved without compromising the environment and environmental services of the planet if we apply that science to creative, imaginative and 21st century public policy-making. thank you very much. kumpula.indd 225kumpula 2003: polar research 22(2), 225–233 it is a commonly accepted tenet that the population dynamics of ungulates in predator-free environments are strongly infl uenced by a combination of stochastic variation and population density (messier 1991; sæther 1997; portier et al. 1998; milner et al. 1999; aanes et al. 2000). as a consequence of stochastic variation, a fi xed, stable equilibrium between herbivores and their food plants is unlikely to exist in natural grazing systems (ellis et al. 1991; behnke & scoones 1992; aanes et al. 2000). however, it has also been observed that population size can oscillate within certain limits in many herbivore populations. therefore it can be supposed that within a longer period population density can fl uctuate around some mean density with a certain variance (murdock 1994; turchin 1995; sæther 1997). it can be also supposed that in reindeer (rangifer t. tarandus) and caribou (r. t. groenlandicus) populations the main source of stochastic variation is of climate-mediated origin. thus, knowledge of the effects of various weather and snow effects of weather and snow conditions on reproduction and survival of semi-domesticated reindeer (r. t. tarandus) jouko kumpula & alfred colpaert in this work we investigated the effects of local weather and snow conditions on the reproduction and survival of semi-domesticated reindeer (rangifer t. tarandus) from 1962 to 1987 in four separate study areas in northern finland. reindeer density had no negative effect on calf percentage in slaughter (october–january) in any area. the higher the number of very warm days or mean temperatures in summer, the lower was the calf percentage in all forested areas (sodankylä, muonio and ivalo). in the muonio area, calf percentage was also reduced by winters with abundant snow accumulation. in the open, mountainous kevo area, calf percentage was reduced with a high number of warm days (mean t > 0 °c) during the previous december. however, if the previous may was warm in that area, it had an opposite effect. high reindeer densities seemed to increase mortality only in the sodankylä area. abundant snow accumulation during winter reduced the survival index of reindeer both in the sodankylä and ivalo areas. in the muonio area, mortality of reindeer was increased with a high number of warm days in december. in the kevo area, reindeer density or any climatic parameters could not explain yearly differences in mortality. this study indicated that permanent changes in climatic conditions could have different impacts in woodland as opposed to open, mountainous regions. in general, if global climatic change means weather instability in early winter and more snow, it also brings more diffi culties for reindeer. however, if climate change means that snow melts earlier in the spring, some conditions could become more favourable for reindeer. j. kumpula, reindeer research station, finnish game and fisheries research institute, fi-99910 kaamanen, finland, jouko.kumpula@rktl.fi ; a. colpaert, dept. of geography, university of oulu, fi-90014 university of oulu, finland. 226 effects of weather and snow conditions on reproduction and survival of reindeer conditions on the demography of reindeer and caribou populations helps us to understand better the fl uctuations of productivity and animal density in these populations. however, if or when stochastic variation is bounded into certain limits, animal density and pasture condition are important measures when trying to optimize pasture use and productivity of reindeer or caribou herds in a long run (klein 1968; skogland 1985, 1986; ouellet et al. 1997; kumpula et al. 1998; fynn & o’connor 2000; kumpula, colpaert et al. 2000; kumpula 2001a; moxnes et al. 2001). there is also an interaction between population density and climatic variables, i.e. the effect of climate is stronger at high than at low reindeer densities (aanes et al. 2000). this is probably because at high animal densities pastures tend to deteriorate and the intensity of direct food competition increases (klein 1968; leader-williams et al. 1987; henry & gunn 1991; manseau et al. 1996; augustine et al. 1998; crête & doucet 1998; alpe et al. 1999; kumpula, colpaert et al. 2000). especially diffi cult snow conditions in winter can increase mortality and reduce the reproduction rate in genus rangifer (klein 1968; helle 1980; reimers 1982; adamczewski et al. 1988; kumpula & nieminen 1992; adams & dale 1998; aanes et al. 2000). another factor explaining much of the yearly variation in body weights of reindeer and caribou in autumn, and also affecting calf mortality, is the level of insect harassment, which has been found to correlate with daily temperatures and wind speed in summer (helle & tarvainen 1984; mörschel & klein 1997; mörschel 1999). a large number of parasitic insects affects reindeer and caribou mainly by decreasing grazing and increasing energy expenditures. the objective of this work was to study the effects of local weather and snow conditions on the reproduction and survival of semi-domesticated reindeer (r. t. tarandus) in four areas in northern finland. vegetation, pastures, topography and climatic conditions differ among the study areas. one important aspect was therefore to look at which weather effects were the most detrimental in each area. reproduction and sur vival of reindeer were studied before 1987 because since then supplementary feeding of rein deer has improved the condition of reindeer, masking the effects of adverse weather conditions (see kojola et al. 1995; kumpula et al. 2002). material and methods weather and snow data from 1961 to 1987 were obtained from four stations of the finnish meteorological institute (sodankylä, muonio, ivalo and kevo) in nothernmost finland (fig. 1). the following parameters for each month were used: mean temperature, maximum temperature, minimum temperature, total precipitation (mm), snow depth on the 15th day, number of days when the mean temperature exceeded 0 °c, 5 °c and 15 °c, and number of days when the maximum temperature was higher than 25 °c. also calculated were mean temperature and total precipitation for january–february, march–april, june–august, september–october and november–december. for the whole summer period (june–august), the following parameters were calculated: the number of days when the mean temperature exceeded 15 °c and the number of days when the maximum temperature was higher than 25 °c. the sum of monthly snow depths was calculated for november–december, january–february, fig. 1. the finnish reindeer management area and the four separate study areas. location of the stations of the meteorological institute in the study areas have been marked. reindeer management districts in kevo are (1) paistunturi and (2) kaldoaivi; in ivalo (3) hammastunturi and (4) ivalo; in muonio (5) muonio and in sodankylä (6) sattasniemi and (7) oraniemi. 227kumpula 2003: polar research 22(2), 225–233 march–april and then november–april. the difference in mean temperature between december and november was also calculated. calf percentage (calves per 100 females) in round-ups (october–january) and the mortality index of reindeer and reindeer density (reindeer/ km² land area, winter stock) were calculated for each year from the statistics of the finnish reindeer herders’ association in the four study areas (fig. 2). the survival index of reindeer was calculated comparing the number of adult (over 1 year old) reindeer counted in round-ups to the number of all reindeer left alive (adults + calves) in the previous year. the survival index was therefore the combination of natural mortality and counting accuracy of reindeer so that both of these elements affected the size of counted reindeer population in a certain year compared to the previous year. although counting accuracy of reindeer has varied between years, the survival index still refl ects a certain level of mortality relatively well in statistical analyses. calf percentage and the yearly survival index were the means of two reindeer management districts in three of the study areas. these reindeer management districts were in the sodankylä area oraniemi and sattasniemi, in the ivalo area ivalo and hammastunturi, and in the kevo area paistunturi and kaldoaivi. in the muonio study area only the muonio reindeer management district was included in the analysis (fig 1). alternations of mean calf percentage, mortality index and reindeer density in the period 1962–1987 are given in fig 2. on the basis of the data from the finnish metorological institute, the mean temperature of the coldest month—february—during 1961– 1990 has been –13.6 °c in sodankylä, –14.5 °c in muonio, –13.0 °c in ivalo and –14.1 °c in kevo. the mean temperature of the warmest month— july—in the same period has been +14.1 °c in sodankylä, +13.7 °c in muonio, +13.7 °c in ivalo and +12.7 °c in kevo. mean snow depth in march during 1961–1990 has been 72 cm in sodankylä, 68 cm in muonio, 65 cm in ivalo and 66 cm in kevo. the sodankylä, ivalo and muonio study areas lie within the northern boreal zone. both in the muonio and ivalo study areas, dry and very dry pine forests as winter pastures are much more common than in the sodankylä area, where submesic and mesic spruce forests have replaced these pastures in late winter. the kevo area belongs to the fjell lapland birch forest zone where dry and very dry mountain birch forests (betula pubescens var tortuosa) and heaths above the tree line form the main winter pastures. during the study period reindeer grazing on natural pastures in the sodankylä area obtained their food in early and mid-winter mainly by digging reindeer lichens (cladonia spp.) and other terrestial plants (like grass, sedges and dwarf shrubs), but in late winter they browsed mainly arboreal lichens (alectoria, bryoria spp.) in spruce forests. in the other three study areas, reindeer lichens and other terrestial plants dominated the diet of reindeer during the whole winter (helle & saastamoinen 1979; kojola et al. 1995). very large open mires are typical of the sodankylä area and form the most important summer pasture type there. although there are considerably fewer mires in the muonio area than in the sodankylä area, mires still have some importance as summer pastures in muonio. in contrast, in the ivalo area there are very few mires areas and submesic forests replace mires as summer pastures. in the kevo area reindeer use mainly submesic birch forests and some mires as summer pastures. the terrain in the muonio area and even more so in the ivalo and kevo areas is much more rugged and hilly than in the sodankylä area, which is relatively fl at. dependency of calf percent and the yearly survival index on weather and snow parameters in the previous year were fi rst analysed with simple regression models. then reindeer density and only those parameters correlating signifi cantly (p ≤ 0.05) with the calf percentage and survival index were used in glm analyses. after that, glm analyses with backwards stepwise (with alpha-to-remove = 0.05) were made with the same independent variables in order to fi nd the most predictive parameters for reproduction and mortality. results contrary to what could be expected, high reindeer densities did not seem to correlate negatively with a low calf percentage in any area (table 1). in the sodankylä and ivalo areas, calf percentage was high when reindeer density was high. when looking only at the effects of weather and snow conditions on calf percentage in the stepwise glm analyses, the higher the number of very warm days or mean temperatures in summer, the lower 228 effects of weather and snow conditions on reproduction and survival of reindeer table 1. effect of reindeer density and weather on calf percentage (calves / 100 females) in the study areas, 1962–1987: results of ordinary glm analyses and glm analyses with stepwise command. rden stands for reindeer density (reindeer / km²) during the previous winter. mtjuly is the mean temperature (°c) in july. day0dec is the number of days in december when the mean temperature is above 0 °c. diftdecnov is the difference in mean temperatures between december and november. max25jul is the number of days in july when the maximum temperature is above 25 °c. snacwin is the sum of the monthly snow depths (on the 15th day of the month) from november to april (cm). mtjune is the mean temperature (°c) in june. mtaug is the mean temperature (°c) in august. max25junaug is the number of days from july to august when the maximum temperature is above 25 °c. day0may is the number of days in may when the mean temperature is above 5 °c. study area effect coeffi cient se std. coef. tolerance t p sodankylä o rd in ar y g l m : constant 45.367 20.623 0.000 – 2.200 0.040 rden 24.015 5.007 0.659 0.926 4.797 0.000 mtjuly –2.258 1.393 –0.250 0.732 –1.620 0.121 day0dec –0.061 1.352 –0.008 0.590 –0.045 0.964 diftdecnov –0.531 0.430 –0.220 0.554 –1.236 0.231 r² = 0.650, n = 25, f = 9.294, p = 0.000 st ep w is e in : constant 60.929 17.604 0.000 – 3.461 0.002 rden 25.272 4.829 0.694 1.000 5.233 0.000 mtjuly –3.262 1.195 –0.362 1.000 –2.731 0.012 r² = 0.613, n = 25, f = 17.458, p = 0.000 muonio o rd in ar y g l m : constant 56.692 21.406 0.000 – 2.555 0.020 rden 6.626 3.813 0.326 0.759 1.738 0.099 max25jul –1.321 1.121 –0.264 0.532 –1.178 0.254 day0dec –1.157 3.287 –0.088 0.432 –0.352 0.729 diftdecnov –0.093 0.514 –0.040 0.550 –0.180 0.859 snacwin –0.062 0.055 –0.281 0.432 –1.129 0.274 r² = 0.518, n = 24, f = 3.876, p = 0.015 st ep w is e in : constant 78.725 11.163 0.000 – 7.052 0.000 max25jul –2.031 0.840 –0.406 0.951 –2.418 0.025 snacwin –0.096 0.037 –0.439 0.951 –2.418 0.016 r² = 0.436, n = 24, f = 8.126, p = 0.002 ivalo o rd in ar y g l m : constant 79.392 28.931 0.000 – 2.744 0.013 rden 13.056 2.976 0.585 0.709 4.387 0.000 mtjune –0.200 1.275 –0.027 0.439 –0.157 0.877 mtaug –2.465 1.865 –0.187 0.632 –1.321 0.203 max25junaug –0.897 0.550 –0.287 0.406 –1.631 0.120 precmay 0.129 0.143 0.124 0.672 0.903 0.378 snacwin –0.069 0.032 –0.265 0.828 –2.148 0.046 r² = 0.773, n = 25, f = 10.212, p =0.000 st ep w is e in : constant 32.262 4.246 0.000 – 7.598 0.000 rden 15.502 2.689 0.695 0.982 5.766 0.000 max25junaug –1.147 0.376 –0.367 0.982 -3.049 0.006 r² = 0.686, n = 25, f = 24.050, p = 0.000 kevo o rd in ar y g l m : constant 1.126 15.543 0.000 – 0.072 0.943 rden 5.278 3.354 0.294 0.810 1.574 0.131 day0dec –3.037 1.691 –0.316 0.916 –1.796 0.088 day0may 1.322 0.639 0.377 0.854 2.070 0.052 r² = 0.433, n = 24, f = 5.083, p = 0.009 st ep w is e in : constant 6.004 15.758 0.000 – 0.381 0.707 day0dec –3.783 1.679 –0.394 0.995 –2.253 0.035 day0may 1.700 0.612 0.485 0.995 2.777 0.011 r² = 0.362, n = 24, f = 5.966, p = 0.009 229kumpula 2003: polar research 22(2), 225–233 fig. 2. (a) variation in mean yearly calf percentage (calves/ 100 females) in round-ups (october–january); (b) the survival index of reindeer; and (c) reindeer density (reindeer/km² land area, winter stock) between 1962–1987 in the study areas. original data were obtained from the statistics of the finnish reindeer herders’ association. (a) (b) (c) 230 effects of weather and snow conditions on reproduction and survival of reindeer was the calf percentage in the next year roundups in all forested areas in sodankylä, muonio and ivalo (table 1). this did not seem to apply in the cooler and more mountainous kevo area. in the muonio area, the calf percentage was also reduced by winters with abundant snow accumulation. in the kevo area, the greater the number of warm days (mean t > 0 °c) in december and the lower their number in may, the lower was the calf percentage in the next autumn round-ups. of all weather variables, abundant snow accumulation during winter was the only one which seemed to reduce the survival index of reindeer in both the sodankylä and ivalo areas (table 2). in the sodankylä area, where reindeer used mainly arboreal lichens in late winter, abundant snow accumulation in march and april seemed to be the most important factor for high mortality. in the ivalo area, where reindeer got their food by digging (cratering) throughout the winter, abundant snow accumulation during the whole winter period increased mortality. also, high reindeer densities seemed to increase mortality in the sodankylä area. in the muonio area, mortality of reindeer was increased when the number of warm days in december was high. in the kevo area, neither reindeer density nor any weather or snow parameters could explain yearly differences in the survival index. discussion on the basis of this work and previous studies (e.g. kumpula & nieminen 1992; helle & kojola 1993), a marked increase in reindeer density in finland since the mid-1970s did not seem to have any negative effect on the reproduction of reindeer. this is probably associated with changes in management practice, including supplemental feeding in the southern half of the area (helle & kojola 1993), and calf harvest (kojola & helle 1993; kumpula et al. 1998), which made the herds strongly female-biased and thus improved the survival rate of the stock. it may also be related to the favourable climatic conditions prevailing during the 1980s (helle et al. 2001). it is very probable that when there is a period of favourable weather and snow conditions, as in our 1980s study period, reproduction is not directly affected by reindeer density. it has been also demonstrated in norway that the reproduction of adult female reindeer was not controlled by population density, although sub-adult fertility was reduced at high animal densities (skogland 1985). in our study, survival of reindeer was reduced at high reindeer densities only in the sodankylä area, where winter pastures were located both in pine and spruce forests. this density dependence may be linked to the fact that the amount of lichen pasture per reindeer in the sodankylä area has been the smallest of the four study areas, which may have caused more competition between reindeer in pastures at high densities. due to the lack of lichen pastures, reindeer in the sodankylä area have also had to graze mainly arboreal lichen in late winter. it may also be supposed that reduction of survival has probably been caused by increased juvenile mortality in winter since juvenile survival has been observed to be the most sensitive to changes in reindeer density (skogland 1985). some clear dependence between local climatic and productivity factors of the semi-domesticated reindeer stock was found. in all forested areas, summer temperatures had a clear effect on calf production. high mean temperatures and large number of very warm days during summer months seemed to reduce calf production. warm weather activates blood-sucking insects and keeps reindeer continuously moving in dense herds and may reduce their grazing and resting times (helle & tarvainen 1984; helle & kojola 1994; mörschel & klein 1997; mörschel 1999). this may exhaust especially smaller calves if calf marking also occurs during a very warm period. especially in woodland area where where high, open, windy ridges and hilltops are not available, blood-sucking insects and high temperatures in summer can form a very exhausting combination for calves. snow accumulation in the previous winter seemed to be an important factor for determining calf percentage or mortality in all three forested areas. the importance of snow depth in the previous winter for ungulate reproduction and body weight has been identifi ed earlier (helle & kojola 1994; adams & dale 1998; loison et al. 1999); deeper snow means usually more digging for food and thus more energy costs (kumpula 2001b). however, it seems that in the kevo area—where there are a lot of open, windy ridges and hilltops with shallow snow—snow accumulation itself has not had any direct effects on calf production or mortality. the kevo meteorological station is located in a deep valley, which can mean that snow conditions in the adjacent mountain area are 231kumpula 2003: polar research 22(2), 225–233 inaccurately registered. however, snow accumulation can affect calf production even in mountain areas: one recent study (helle et al. 2001) has shown that snowy winters reduced the calf percentage and affected yearly change in population size in the käsivarsi mountain area, which is located nearer the western coast of northern scandinavia than our study area. generally, there seems to be three important periods for succesful reproduction and survival in a year: early winter, spring and mid-summer. weather and snow conditions, particularly in december, essentially affect the development of those conditions which regulate the availability and quality of terrestrial winter food (kumpula, parikka et al. 2000). if there are warm decembers with temperatures fl uctuating around 0 °c, a hard snow or ice layer can form on vegetation which then hampers foraging during the whole winter. this is probably a more important factor than snow accumulation itself in open, high pasture areas compared to woodland pasture areas. especially in woodland areas, a thick snow layer on unfrozen soil in early winter can hamper digging but may also promote the growth of certain micro-fungi on vegetation (kumpula, parikka et al. 2000). these micro-fungi may then be harmful for the reindeer health. the body condition of reindeer females during calving is thus much affected by weather and snow conditions in late autumn and early winter. for reindeer herders, early winter vegetation and snow conditions, which may then affect the availability and quality of terrestrial food during the rest of the winter, table 2. effect of reindeer density and weather on the survival index of reindeer in the study areas, 1962–1987: results of ordinary glm analyses and glm analyses with stepwise command. rden stands for reindeer density (reindeer / km²) during the previous winter. snacmayapr is the sum of the monthly snow depths (on 15th day of the month) from march to april (cm). day0dec is the number of days in december when the mean temperature is above 0 °c. snacwin is the sum of the monthly snow depths (on the 15th day of the month) from november to april (cm). study area effect coeffi cient se std. coef. tolerance t p sodankylä o rd in ar y g l m : constant 110.962 20.150 0.000 . 5.507 0.000 rden –16.681 7.584 –0.322 0.986 –2.199 0.039 snacmayapr –0.587 0.121 –0.712 0.986 –4.859 0.000 r² = 0.556, n = 24, f = 13.127, p = 0.000 st ep w is e in : the same as above muonio o rd in ar y g l m : constant 0.471 20.604 0.000 . 0.023 0.982 rden 1.449 4.128 0.060 0.839 0.351 0.729 day0dec –11.331 3.534 –0.692 0.522 –3.206 0.004 snacwin –0.003 0.059 –0.010 0.470 –0.046 0.964 st ep w is e in : r² = 0.514, n = 24, f = 7.053, p = 0.002 constant 2.537 2.865 0.000 – 0.885 0.386 day0dec –11.702 2.443 –0.714 1.000 –4.789 0.000 r² = 0.510, n = 24, f = 22.935, p = 0.000 ivalo o rd in ar y g l m : constant 88.799 26.188 0.000 – 3.391 0.003 rden –7.436 7.127 -0.188 0.996 –1.043 0.309 snacwin –0.262 0.086 -0.549 0.996 –3.056 0.006 r² = 0.324, n = 24, f = 5.032, p = 0.016 st ep w is e in : constant 78.484 24.299 0.000 – 3.230 0.004 snacwin –0.257 0.086 –0.538 1.000 –2.990 0.007 r² = 0.289, n = 24, f = 8.940, p = 0.007 232 effects of weather and snow conditions on reproduction and survival of reindeer have always been very important to estimate. in our data, the number of warm days in december as well as the difference in average temperatures between december and november probably indicate something about the development of snow conditions as well as soil temperatures and the formation of permanent ground frost in soil in early winter. may is another important month for successful calf production especially in the northernmost part of the finnish reindeer management area. after a warm, rainy may, the calf percentage seems to be high. this kind of weather probably causes rapid snow melt and the early emergence of green vegetation (kumpula & nieminen 1992) or can simply improve the availability of winter food when snow melts earlier (helle et al 2001). this will improve the body condition of reindeer females and thus favour calving. this study indicates that permanent climate changes could affect woodland and open, mountainous areas in different ways. there should be broader knowledge of the effects of local weather conditions, and their variations, on vegetation and reindeer populations and in which way the potential global climatic variation or change affects local weather and snow conditions. one index of global climate fl uctuations, the north atlantic oscillation (nao), has been observed to correlate with plant phenology (post & stenseth 1998) and snow conditions (mysterud et al. 2000) in norway. plants bloomed earlier following positive nao (warm, wet) winters, but the timing of fl owering varied with the nao more strongly in southern than in northern norway. early-blooming plants were more strongly infl uenced by the nao than late-blooming plants. snow depth was negatively correlated with the nao at low altitudes but this relationship was reversed at high altitudes, giving a positive correlation between snow depth and the nao. it has been also shown that positive nao winters with high precipitation and warm weather are mostly adverse for ungulate populations in northern latitudes (excluding the coast of norway and the isle of rum, scotland), reducing body weight, reproduction and population growth rate and increasing mortality (post & stenseth 1999; mysterud et al. 2000). the nao index has also been observed to have a strong impact on the population dynamics of semi-domesticated reindeer in the käsivarsi area, northern finland (helle et al. 2001). reduction of calf production and population size followed both highly negative and positive nao winters. this work has shown that variation in local weather and snow conditions, especially in early winter and spring, as well as snow accumulation during winter, could have a strong impact on the reindeer population in northern finland. the clear impacts of summer temperatures on calf production of reindeer were also demonstrated. it is evident that if global climatic change means higher instability of weather in early winter and more snow during the whole winter in northern latitudes, conditions become more diffi cult for reindeer. these effects can be even more adverse if summer temperatures rise high. on the other hand, if climate change brings earlier snow melting in spring, it can make some conditions more favourable for reindeer. acknowledgements.—we wish to thank jukka siitari and tuomo haurunen from the reindeer research station at the finnish game and fisheries research institute for help in handling the data. for reindeer census data we thank the finnish reindeer herders’ association. gordon roberts is thanked for improving the english. this work is partly connected to the project no: 52759 in the sunare research programme, which is supported by the finnish academy. references aanes, r., sæther, b.-e. & øritsland n. a. 2000: fluctuations of an introduced population of svalbard reindeer: the effects of density dependence and climatic variation. ecography 23, 437–443. adamczewski, j. z., gates, c. c., soutar, b. m. & hudson, r. j. 1988: limiting effects of snow on seasonal habitat use and diets of caribou (rangifer tarandus groenlandicus) on coats island, northwest territories, canada. can. j. zool.66, 1986–1996. adams l. g. & dale b. w. 1998: reproductive performance of female alaskan caribou. j. wildl. manage. 62, 1184–1195. alpe, m. j., kingery, j. m. & mosley, j. c. 1999: effects of summer sheep grazing on browse nutritive quality in autumn and winter. j. wildl. manage. 63, 346–354. augustine, d. j., frelich, l. e. & jordan, p. a. 1998: evidence for two alternate stable states in an ungulate grazing system. ecol. appl. 8, 1260–1269. behnke, r. h. & scoones, i. 1992: rethinking range ecology: implications for rangeland management in africa. int. inst. environ. dev. pap. 33. crête, m. & doucet, g. j. 1998: persistent suppression in dwarf birch after release from heavy summer browsing by caribou. arct. alp. res. 30, 126–132. 233kumpula 2003: polar research 22(2), 225–233 ellis, j. e., coughenour, m. b. & swift, d. m. 1991: climate variability, ecosystem stability, and the implications for range and livestock development. in r.h. behnke et al. (eds.): range ecology at disequilibrium: new models of natural variability and pastoral adaption in african savannas. pp. 31–41. london: overseas development institute. fynn, r. w. s. & o’connor, t. g. 2000: effect of stocking rate and rainfall on rangeland dynamics and cattle performance in a semi-arid savanna, south africa. j. appl. ecol. 37, 491–507. helle, t. 1980: laiduntilanteen muutokset ja riskinotto suomen porotaloudessa. (changes in the state of grazing areas and risk-taking in finnish reindeer management. in finnish with english summary.) lapin tutkimusseuran vuosikirja xxi, 13–22. helle, t. & saastamoinen, l. 1979: the winter use of food resources of semi-domestic reindeer in northern finland. commun. inst. for. fenn. 95, 1–26. helle, t. & tarvainen, l. 1984: effects of insect harassment on weight gain and survival of reindeer calves. rangifer 4, 24–27. helle, t. & kojola, i. 1993: reproduction and mortality of finnish semi-domesticated reindeer in relation to density and management strategies. arctic 46, 72–77. helle, t. & kojola, i. 1994: body mass variation in semidomesticated reindeer. can. j. zool. 72, 681–688. helle, t., kojola, i. & timonen, m. 2001: lumipeitteen vaikutus käsivarren porolukuihin: mikä on pohjois-atlantin säävaihtelun (nao) merkitys? (impact of snow cover on the reindeer population in käsivarsi, nw finland: is the north atlantic oscillation (nao) involved? in finnish with english summary.) suom. riista 47, 75–85. henry, g. h. r. & gunn, a. 1991: recovery of tundra vegetation after overgrazing by caribou in arctic canada. arctic 44, 38–42. klein, d. r. 1968: the introduction, increase, and crash of rein deer on st. matthew island. j. wildl. manage. 32, 350–367. kojola, i. & helle, t. 1993: calf harvest and reproductive rate of reindeer in finland. j. wildl. manage. 57, 451–453. kojola, i., helle, t., niskanen, m. & aikio, p. 1995: effects of lichen biomass on winter diet, body mass and reproduction of semi-domesticated reindeer rangifer t. tarandus in finland. wildl. biol. 1, 33–38. kumpula, j. 2001a: productivity of the semi-domesticated rein deer (rangifer t. tarandus l.) stock and carrying capacity of pastures in finland during 1960–1990’s. acta univer sitatis ouluensis a 375, scientiae rerum naturalium. ph.d. thesis, university of oulu. kumpula, j. 2001b: winter grazing of reindeer in woodland lichen pasture: effect of lichen availability on the condition of reindeer. small ruminant res. 39, 121–130. kumpula, j., colpaert, a. & nieminen, m. 1998: reproduction and productivity of semi-domesticated reindeer in northern finland. can. j. zool.76, 269–277. kumpula, j., colpaert, a. & nieminen, m. 2000: condition, potential recovery rate, and productivity of lichen (cladonia spp.) ranges in the finnish reindeer management area. arctic 53, 152–160. kumpula, j., colpaert, a. & nieminen, m. 2002: productivity factors of the finnish semi-domesticated reindeer (rangifer t. tarandus) stock during the 1990s. rangifer 22, 47–56. kumpula, j. & nieminen, m. 1992: pastures calf production and carcass weights of reindeer calves in the oraniemi cooperative, finnish lapland. rangifer 12, 93–104. kumpula, j., parikka, p. & nieminen, m. 2000: occurence of certain microfungi on reindeer pastures in northern finland during winter 1996–97. rangifer 20, 3–8. leader-williams, n., smith, r. i. l. & rothery, p. 1987: infl uence of introduced reindeer on the vegetation of south georgia: results from a long-term exclusion experiment. j. appl. ecol. 24, 801–822. loison, a., langvatn, r. & solberg, e. j. 1999: body mass and winter mortality in red deer calves: disentangling sex and climate effects. ecography 22, 20–30. manseau, m., huot, j. & crête, m. 1996: effects of summer grazing by caribou on composition and productivity of vegetation: community and landscape level. j. ecol. 84, 503– 513. messier, f. 1991: on the concepts of population limitation and population regulation as applied to caribou demography. in c. e. butler & s. p. mahoney (eds.): proceedings of the fourth north american caribou workshop. pp. 260–277. st. john’s: newfoundland labrador wildlife division. milner, j. m., elston, d. a. & albon, s. d. 1999: estimating the contributions of population density and climatic fl uctuations to interannual variation in survival of soay sheep. j. anim. ecol. 68, 1235–1247. moxnes, e., danell, ö., gaare, e. & kumpula, j. 2001: optimal strategies for the use of reindeer rangelands. ecol. model. 145, 225–241. mörschel, f. m. 1999: use of climatic data to model the presence of oestrid fl ies in caribou herds. j. wildl. manage. 63, 588–593. mörschel, f. m. & klein, d. r. 1997: effects of weather and par a sitic insects on behaviour and group dynamic of caribou of the delta herd, alaska. can. j. zool. 75, 1659– 1670. murdock, w. w. 1994: population regulation in theory and practice. ecology 75, 271–287. mysterud, a., yoccoz, n. g., stenseth, n. c. & langvatn, r. 2000: relationships between sex ratio, climate and density in red deer: the importance of spatial scale. j. anim. ecol. 69, 959–974. ouellet, j.-p., heard, d. c., boutin, s. & mulders r. 1997: a comparison of body condition and reproduction of caribou on two predator-free islands. can. j. zool. 75, 11–17. portier, c., festa-bianchet, m., gaillard, j.-m., jorgenson, j. t. & yoccoz, n. g. 1998: effects of density and weather on survival of bighorn sheep lambs (ovis canadensis). j. zool. 245, 271–278. post, e. & stenseth, n. c. 1998: large-scale climatic fl uctuation and population dynamics of moose and white-tailed deer. j. anim. ecol. 67, 537–543. post, e. & stenseth, n. c. 1999: climatic variability, plant phen ol ogy, and northern ungulates. ecology 80, 1322–1339. reimers, e. 1982: winter mortality and population trends of reindeer on svalbard, norway. arct. alp. res. 14, 295–300. sæther, b.-e. 1997: environmental stochasticity and population dynamics of large herbivores: a search for mechanisms. trends evol. ecol. 12, 143–149. skogland, t 1985: the effects of density dependent resource limitations on demography of wild reindeer. j. anim. ecol. 54, 359–374. skogland, t. 1986: density dependent food limitation and max imal production in wild reindeer herds. j. wildl. manage. 50, 314–319. turchin, p. 1995: population regulation: old arguments and a new synthesis. in n. cappuccino & p. w. price (eds.): population dynamics. pp. 19–40. san diego, ca: academic press. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /all /binding /left /calgrayprofile (dot gain 20%) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages true /colorimagedownsampletype /bicubic /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages true /grayimagedownsampletype /bicubic /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /fra <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> /enu (use these settings to create pdf documents with higher image resolution for improved printing quality. the pdf documents can be opened with acrobat and reader 5.0 and later.) /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308000200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e30593002537052376642306e753b8cea3092670059279650306b4fdd306430533068304c3067304d307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e30593002> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <feff00550073006100720065002000710075006500730074006500200069006d0070006f007300740061007a0069006f006e00690020007000650072002000630072006500610072006500200064006f00630075006d0065006e00740069002000500044004600200063006f006e00200075006e00610020007200690073006f006c0075007a0069006f006e00650020006d0061006700670069006f00720065002000700065007200200075006e00610020007100750061006c0069007400e00020006400690020007300740061006d007000610020006d00690067006c0069006f00720065002e0020004900200064006f00630075006d0065006e00740069002000500044004600200070006f00730073006f006e006f0020006500730073006500720065002000610070006500720074006900200063006f006e0020004100630072006f00620061007400200065002000520065006100640065007200200035002e003000200065002000760065007200730069006f006e006900200073007500630063006500730073006900760065002e> /nor <feff004200720075006b00200064006900730073006500200069006e006e007300740069006c006c0069006e00670065006e0065002000740069006c002000e50020006f00700070007200650074007400650020005000440046002d0064006f006b0075006d0065006e0074006500720020006d006500640020006800f80079006500720065002000620069006c00640065006f00700070006c00f80073006e0069006e006700200066006f00720020006200650064007200650020007500740073006b00720069006600740073006b00760061006c0069007400650074002e0020005000440046002d0064006f006b0075006d0065006e00740065006e00650020006b0061006e002000e50070006e006500730020006d006500640020004100630072006f0062006100740020006f0067002000520065006100640065007200200035002e00300020006f0067002000730065006e006500720065002e> /sve <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> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice landsat tm derived and in situ summer reflectance of glaciers in svalbard jan-gunnar winther winther, j-g. 1993: landsat tm derived and in situ summer reflectance of glaciers in svalbard. polar research 12(1), 37-55. the paper presents satellite-derived and in situ reflectance from the austre br~ggerbreen and midre lovcnbreen glaciers located 78"50", 1 l"50'e in the svalbard archipelago. the satellite data are landsat 5 tm images recorded on 7 august 1987 and 31 august 1988. in situ measurements of shortwave and spectral reflectance of snow, glacier ice and moraine were carried out in august 1991 and in june 1992. in 1987, austre br~ggerbreen had a positive net mass balance of +0.22 m of water equivalent while the net mass balance i n 1988 was negative (-0.52 m). this is reflected in the atmospherically corrected satellite derived albedo which shows that the reflective characteristics of the ablation and accumulation zones are more uniform and better separated in 1987 than in 1988. besides the long-term year to year variations of surface albedo, the glaciers show a considerable short-term as well as spatial variability in reflectance. for example, the satellite-derived tm band 4 albedo was found to vary between 0.19 and 0.65 at midre lovtnbreen on 31 august 1988. in silu measurements show a drop in daily mean albedo from 0.88 to 0.13 during 4 days at a fixed location on austre br~ggerbreen i n august 1991 (300 m.a.s.1.). furthermore, spectral measurements of snow albedo in june 1992 clearly demonstrate that the near-infra-red albedo decreases when the snow metamorphoses, i.e. when the characteristic grain size increases. the effect of cloud cover on the snow albedo is also discussed. the integrated albedo (37cl900 nm) increased from 0.812 to 0.869 (7%) when the weather condition changed from clear sky to 100% overcast within 2 hours on 9 june 1992. the bidirectional reflectance of snow is measured by taking spectral scans for viewing angles 0" (nadir), 15". 30". 45" and 60" for viewing directions facing the sun and at azimuths 90" and 180" away from the sun. the increase i n albedo relative to the nadir albedo is found to be 8, 15, 19 and 26% for viewing angles 15". 30". 45" and 60". respectively. the largest anisotropy is seen for metamorphosed snow in measurements facing the sun. consequently, i t may be necessary to correct for the specular properties of snow if satellite-derived surface reflectance is going to be considered in terms of absolute values. jan-gunnar winther, sintef norwegian hydrotechnical laboratory, n-7034 trondheim, norway. introduction studies of the mass balance of the small glaciers of the world have become increasingly important as these glaciers respond to changes in regional climate on the scale of decades and can thus serve as indicators of regional climate change. landsat multispectral scanner (mss) and landsat the matic mapper (tm) data have been available since 1972 and 1982, respectively. the satellite data provide digital images for analysing the posi tion of the equilibrium line (0strem 1975; hall & ormsby 1983), glacier facies (williams et al. 1991), glacier reflectance (zeng et al. 1984; hall et al. 1987, 1989, 1990), terminus position and changes in glacier area (hall et al. 1992a). the ablation and accumulation areas of a gla cier are separated by the equilibrium line. the snow line is defined as the lower border of the snow from last winter and often represents the approximate location of the equilibrium line at the end of an average mass balance year. the equilibrium line altitude (ela) can be well cor related with the net balance (schytt 1981; young 1981; hagen & liestcbl 1990). moreover, the dig ital landsat tm data (30 metres pixel resolution) is well suited for positioning the snow line and thus can be used for studies of glacier mass balance. however, as a zone of superimposed ice can form between the snow line and the equi librium line, the exact location of the equilibrium line can become complicated. superimposed ice forms when water percolates through the wet snow and refreezes on the underlying glacier ice (wakahama et al. 1976; paterson 1981). a broad zone (up to 1 km) of superimposed ice is normally 38 j-g. winther formed at austre brcdggerbreen, making the posi tioning of the equilibrium line by satellite remote sensing difficult. the ablation area consists of exposed ice during the summer and represents an area where net loss occurs by melting. the accumulation area can be divided into the wet-snow, percolation and dry snow facies. obviously, the different facies rep resent snow and ice surfaces with quite different characteristics with respect t o reflectance. thus, the facies and their characteristic surface reflec tance (or albedo) are important in terms of energy exchange between the glacier and the surrounding air mass. even small changes in snow reflectance can have a significant effect on the earth-atmos phere energy balance (warren & wiscombe 1985). this paper mainly emphasises (1) temporal and spatial variations of glacier summer albedo, and (2) anisotropic snow reflectance and its effect on the calculated satellite-derived albedo. the study presents the satellite-derived glacier albedo recorded by landsat-5 th4 in august 1987 and august 1988 together with in situ albedo measure ments of snow, ice and moraine in the same area in august 1991 and june 1992. both the in situ and the satellite-derived measurements demonstrate the large range of surface albedo present on the glacier, especially at the end of the mass-balance year (i.e. normally in late august). further, off nadir spectral measurements of snow reflectance are presented and illustrate the anisotropic reflectance properties of snow. it is shown how the bidirectional reflectance of snow varies when the direction of the sensor changes both hori zontally and vertically. the study points out that correction for anisotropic snow reflectance may be needed if the calculated satellite-derived snow albedos are going t o be considered as absolute values. study area the svalbard archipelago is situated between lati tudes 76"n and 81"n and longitudes 10"e and 35"e in the norwegian arctic (fig. 1). the total area is about 63,000 km2 and 60% is covered by glaciers (sand et al. 1991). the ice-free areas in svalbard have continuous permafrost. the thick ness of the permafrost varies from less than 100 m close to sea level up t o 500 m in the higher moun tainous areas (liestd 1977). fig. 1. the svalbard archipelago and the study area (encircled). the study area lies in the kongsfjorden area on the western coast of spitsbergen (fig. 1). several glaciers drain into the kongsfjorden inlet and satellite-derived surface reflectance has been recorded for two of the glaciers, austre brag gerbreen and midre lovcnbreen. in situ measure ments were carried out on austre brcdggerbreen in august 1991 and june 1992. austre brcdg gerbreen is the eastern part of the larger brcdg gerbreen glacier (figs. 2 and 3). br~ggerbreen glacier is a 5 km2 subpolar glacier located 78"50'n, 1 l"50'e on the brcdggerhalvcdya peninsula, close to the research station in ny-alesund (hagen et al. 1991). the glacier stretches from about 75m.a.s.l. at its retreating front to about 575 m.a.s.1. the glacier front is flat and the main flow direction is towards the north. there are few crevasses on the glacier due to very slow movement of the ice mass. mass balance measurements show a steadily decreasing ice mass since 1968 (hagen & liest01 1990). background and methods glacier facies glaciers are composed of an ablation and an accumulation area. within these two areas several facies might be present (fig. 4). the facies rep resent distinctive areas with characteristics that fig. 2. part of a landsat thematic mapper tm bands 2 . 4 and 5 composite image recorded on 7 august 1987 (512 x 512 pixels). austre breggerbreen (left arrow) and midre lovcnbreen (right arrow) lie on the breggerhalv@ya peninsula due south of the kongsfjorden inlet. austre broggerbreen terminates on land at about 75 m.a.s.1. the upper part of the glacier stretches up to 575 m.a.s.1. and the main flow direction is towards north i e . , towards the upper left corner of the image. the lower part of the glacier has low reflectance due to morainal deposits and exposed blue ice. a transition zone of superimposed ice is seen close to the arrow while the upper part is covered by snow. fig. 3. landsat thematic mapper tm bands 2, 4 and 5 composite image of austre braggerbreen recorded on 7 august 1987. shaded areas of the glacier are masked out. blue ice is exposed in the lower parts of the glacier (upper left). the superimposed ice zone can be seen left of the centre of the image (light blue) while the upper parts of the glacier constitute the wet-snow zone (right part of the image). 40 j-g. winther glader surface at end d the ahation period surface d subglacier terrain ~~ fig. 4. cross-section of a glacier showing facies at the end of the balance year from glaciological field observations (figure modified from williams et al. 1991). reflect the environment under which the snow or ice was formed. the accumulation area is typically composed of wet-snow facies, percolation facies and dry-snow facies (benson 1959, 1967; mulfer 1962; benson & motyka 1979; williams e t a l . 1991). however, due to long periods of mild weather which influence the glacier surface at all altitude levels, the accumulation area of austre braggerbreen consists predominantly of wet snow facies at the end of the ablation period. superimposed ice is formed by (1) the refreez ing of meltwater during the autumn and/or during the ablation period and (2) the refreezing of meltwater on the glacier surface below the snow line at the end of the ablation period (parrot et al. 1993). furthermore, net loss by melting occurs in the ice facies. on austre br~ggerbreen the ice facies mainly consist of blue ice partly covered by morainal deposit. consequently, the surface is honeycombed due to a non-uniform distribution of ablation. in addition, meltwater flow creates a complex surface pattern which looks like a grid system with irregular angles and highly varying dimensions in the x, y and z-directions. because of the low reflectance, the ice facies can normally be easily distinguished from the snow facies. even so, many natural features on a glacier can obscure facies boundaries and make them hard to separate by satellite remote sensing. such features can be a new snowfall or desert/volcanic dust (hall et al. 1987). however, difficulties in separating the ablation area from the surrounding ice-free area are more common. this is because the low reflec tance of the glacier terminus caused by rock debris, may be similar to the adjacent morainal and outwash-plain materials (williams et al. the equilibrium line altitude (ela) often cor responds quite closely with the snow line altitude (williams et al. 1991). however, parrot et al. (1993) carried out a study on austre brbg gerbreen and midre lodnbreen and pointed out that the ela is located within the zone of super imposed ice on these glaciers. this is confirmed by hagen & liest01 (1990) who report that the altitude of the transient snow line may be far above the actual ela, and the altitude difference varies just as the amount of superimposed ice varies. today the ela is located from stake readings on austre braggerbreen. hagen & lie stal (1990) made use of simple linear regression analysis and calculated the correlation between the net mass balance and the ela (1967-88) to be 0.961 and 0.953 for austre braggerbreen and 1991). summer reflectance of glaciers in svalbard 41 takes place in the infra-red region. consequently, all tm bands 1-4 can be used to distinguish snow from firn and ice facies. further downstream, the surface at the glacier terminus is honeycombed because of the dirty moraine and non-uniform distribution of ablation. the reflectance lies close to 0.6 for glacier ice and at about 0.2 for dirty glacier ice in the visible range, but increases a little in the infra-red due t o the presence of moraine (zeng et al. 1984). thus, the visible tm bands are suitable for separating dirty glacier ice from (clean) glacier ice whereas tm band 4 is unsuited to this purpose. finally, fig. 5 shows that glacier ice has a larger reflectance than refreezing ice in the visible region while the oppo site is the case in the infra-red region. midre lovcnbreen, respectively. thus, on gla ciers where the ela can be localized by satellite remote sensing techniques, this can give valuable information about the mass balance of these gla ciers. spectral reflectance of snow and glacier ice the portion of radiation reflected from a surface consisting of fresh snow remains high in the visible region while a distinct drop occurs in the near infra-red (fig. 5). furthermore, the snow albedo drops below 0.10 in the middle-infra-red region where tm bands 5 and 7 are located (outside the wavelength range shown in fig. 5). tm bands 1, 2 and 3 are sensitive to visible blackening of the snow surface such as deposition of dust and organic material (dozier et al. 1981). albedo reduction caused by snow grain coarsening and increasing liquid water content is most prominent in the near-infra-red making tm band 4 the most appropriate band for detection of snow meta morphosis process (bryazgin & koptev 1969; choudhury & chang 1979). fig. 5. shows the spectral curves of fresh snow, firn, glacier ice, refreezing ice and dirty glacier ice. the visible reflectance declines from 0.95 t o 0.60 as the snow cover metamorphoses to glacier ice (fig. 5). a similar reduction of reflectance 1 .o 0.9 0.8 0.7 0.6 5 0.5 m 2 0 4 c * 0.3 ',.fresh snow --. _ \ \ r -'. i \glacier i c e \ \ '\ /*.\ , f -. \dl \ \ \ . .. , . . . , .... ./----- 0.1 400 500 800 700 800 900 1000 1100 wavelength (nrn) fig. 5. spectral reflectance curves for snow and ice in different formation stages (figure modified from zeng et al. 1984). the landsat thematic mapper data set the landsat-5 satellite, launched in march 1984, carries a multispectral scanner subsystem (mss) and a thematic mapper (tm) onboard. the tm senses in the following bands (lillesand & kiefer 1987): tml tm2 tm3 tm4 tm5 tm6 tm7 0.45-0.52 pm 0.52-0.60 pm 0 . 6 w . 6 9 pm 0.760.90 pm 1.551.75 pn 10.40-12.50 pn 2.0%2.35 pm tm band 6 lies in the thermal-infra-red part of the em spectrum and has a spatial resolution of 120111. the other tm bands (bands 1-5 and 7) are located within the visible, near-infra-red and mid-infra-red wavelength regions. they have a spatial resolution of 30 m. spectral signatures from snow at these wavelengths make them suit able for studies of grain size and surface impurities (dozier 1984). the images used in this study are landsat-5 tm scenes from august 7 , 1987, and august 31, 1988. both images are cloud-free and are recorded at 12:21 and 11:44 (gmt), respect ively. the solar elevation is 26.8" in the image from 1987 and 18.6" in the image from 1988. data saturation is common in regions with high reflection such as snow-covered terrain and is reported by many investigators (dozier 1985; orheim & lucchitta 1988; hall et al. 1990). severe data saturation occurs in tm band 1 in both images. 42 j-g. winther by converting the digital numbers (dns) obtained from the digital tm data, surface reflec tance and thus the albedo was computed. a con version procedure is described by markham & barker (1986). this method is widely used (hall et al. 1988; orheim & lucchitta 1988; dozier 1989) and is applied to the landsat tm images used in this study as well. the conversion is impor tant since albedo is a physical parameter and is used for example in general circulation models (gcms) and in energy budget models. the albedo is expressed as the ratio of total reflected radiation to total incident radiation. total reflec ted radiation includes hemispherical surface reflection integrated over the reflective regions of the em spectrum. effects of atmosphere, topography and anisotropic refrectance on satellite-derived albedo three important factors influence the accuracy of the calculated at-satellite planetary reflectance: (1) atmospheric effects caused by gaseous absorp tion and scattering by molecules and aerosols, (2) topographic effects due to the fact that illumi nation and reflectance from sloping areas deviate from the true spectral response characteristics to these areas, and (3) anisotropic snow reflectance because an increased portion of the scattering occurs in the forward direction as snow meta morphoses. atmospheric correction of the images is camed out using the 5s computer code for the simulation of satellite signals in the solar spectrum (tanre et al. 1990). the 5s code allows the estimation of solar radiation backscattered by the earth-sur face-atmosphere system, as it is observed by a satellite sensor. corrections are based on input specifications like geometrical conditions, atmospheric model (subarctic summer), aerosol characteristics (type and concentration), spectral band of observation and a given ground reflec tance. for a specified ground reflectance the cor responding at-satellite reflectance is computed by the model. then, apparent reflectance might be calculated for different specific ground reflec tances, for example with increments of 0.1. fur thermore, simple linear regression using at satellite reflectances as the independent variable and ground reflectance as the dependent variable has been carried out. when the regression can easily be calculated for every pixel in the image. for the two tm images, the satellite derived surface reflectance is underestimated if no correction is carried out. influence from topography can be separated in effects related to the illuminated pixel itself and to effects from adjacent slopes (hall et al. 1988). with respect to the former, the geometry between the sun, the target orientation and the sensor might vary from one pixel to another. therefore, this normally results in darker parts of the image facing away from the sun and the brighter areas being sun-facing slopes. the topographic effects are most pronounced at low solar elevations and for slopes close to the principal plane of the sun (holben & justice 1979). concerning the latter, the topographic environment may (1) cast shadows on a pixel so that it receives no direct radiation at all, (2) reduce the scattered sky radi ation by hiding a part of the sky hemisphere and (3) reflect the radiation towards the pixel, consequently giving an additional irradiance (proy et al. 1989). digital terrain models for topographic correction of the tm-images have not been used in this study. however, areas in shadow and areas where rocks stick out frequently (below and right of the arrow in fig. 2) have been masked and excluded in the data presented in the results and discussion section. snow is an anisotropic reflector after it has begun to metamorphose (dirmhirn & eaton 1975; steffen 1987; dozier et al. 1988; hall et al. 1988, 1992b). though freshly fallen snow can be considered a lambertian reflector, as snow metamorphoses the specular component charac teristic of forward scattering increases. then, since the landsat sensors are nadir-viewing, the satellite-derived reflectance will often provide different reflectances compared to the hemi spheric reflectance on the ground. this subject is covered in more detail in the results and discus sion section. in situ instrumentation and measurements a kipp and zonen albedometer (model cm 7) measured the surface albedo on austre breg gerbreen at 300 m.a.s.1. from 16-28 august 1991. the albedometer consists of two identical pyranometers, model cm 5 . one measures the incident solar radiation, the other the radiation reflected bv the surface. when the outout of the equations are establlshed,.the ground reflectance summer reflectance of glaciers in svalbard 43 pyranometers is recorded separately, the albedo can be calculated from the ratio between these outputs. white lacquered screens prevent the cm 7 albedometer housing from being heated by radi ation. in addition, the lower screen prevents the illumination of the lower glass domes directly by the sun near sunrise and sunset. the albedometer is sensitive (panchromatic) for wavelengths from 305 nm to approximately 2800 nm. the logging interval was set to 10 minutes. initially, the sensor height was 1.55 m but increased to 1.85 m due to snow melting during the first week. then, a storm broke out and the albedometer was lowered to 1.10 m to reduce the wind forces on the instrument and its stand. the illuminated surface consisted initially of 30 cm of wet snow with a characteristic grain size of 2 3mm overlying the glacier ice. gradually, the snow melted and the surface conditions turned t o a mixture of snow, water puddles and blue ice. later, a smooth slippery and wet blue ice surface was exposed. finally, on the last day of measure ments, fresh snow began to accumulate on the blue ice. in addition to the albedo recordings, air and snow temperature, density, liquid water content, grain size and shape, snow hardness and stratification were measured in shallow snow pits at height intervals of 25m between 300 and 600 m.a.s.1. grain size was registered by macro photography of snow grains placed on a black crystal screen with a white grid scale indicator. the snow pits were placed along the centre line of the glacier. in 1992, in situ measurements were acquired using the se 590 spectrometer. the se 590 meas ures radiation between 370 and 111onm in 252 discrete steps, i.e. each channel represents a bandwidth of approximately 3 nm. the spectral resolution is about 10 nm. the field of view of the sensor is 6" and the surface area covered by the sensor represents about 14 cm2 for the measure ments presented here. the spectral detector head was fastened to a standard camera tripod to avoid movements during the integration time of the sensor that was less than 1 second. immediately after each snow measurement sequence, a spec tral measurement of a halon target at 0" nadir angle was taken as a reference for the calculations of albedo. the solar and atmospheric conditions are considered to be stable during one scan sequence. the limits of the sensitivity of the sili con detectors are reached, in the .near-infra:red region, and the signabto-noise ratio is small beyond 900nm (dozier e t al. 1988; hall et al. 1992b). therefore, only data between 370 and 900 nm is presented. in addition to measurements of snow reflectance, some spectral reflectance curves of moraines in the terminus area were taken. daily measurements from 2-10 june 1992, of spectral reflectance of snow, air and snow tem peratcre, density, liquid water content, grain size and shape, snow hardness and stratification were acquired at a measuring site downstream from the terminus of austre br@ggerbreen at 15 m.a.s.1. these measurements were also carried out at height intervals of 25m between 50 and 525 m.a.s.1. along the centre line of the glacier. scan sequences of snow reflectance were acquired by pointing the spectral detector head at nadir (o"), and 15", 30", 45" and 60" off-nadir followed by a nadir reference measurement of the halon target. such a scan sequence typically took less than 2min. the azimuthal directions of the measurements were towards the sun, and 90" and 180" away from the sun (fig. 6). shadows from the tripod introduced an error at some of the viewing angles under clear sky conditions for the measurements facing 180" away from the sun. . . 0' 15' 30' 45' 60' fig. 6. viewing geometry of the measurements. the upper part of the figure shows the horizontal viewing directions where 0" refers to measurements facing the sun. the lower part of the figure shows the vertical viewing directions for measurements facing the sun. similar off-nadir measurements were made in the directions facing 90" and 180" away from the sun, i.e., each indhted point in the upper figure represents one spectral measurement. 44 j-g. winther results and discussion satellite-derived surface albedo of austre br@ggerbreen and midre lovtnbreen both austre braggerbreen and midre lovkn breen are masked out of the sub-image seen in fig. 2. fig. 3 shows austre braggerbreen after the masking. next, analysis of the two glaciers are made. surface reflectance expressed by the dns shows that the visible and near-infra-red reflectance (i.e. tm bands 2 and 4) is generally higher in 1987 than in 1988 (table 1). only two years of positive net mass balance are recorded on austre braggerbreen in the period 19661991 and the largest positive value is found in 1987 (+0.22 m of water equivalent). 1988 is close to a normal year with a net mass balance of -0.52 m. the average net ass balance for 1966-91 is -0.42 m (hagen, pers. commun.). fig. 7 presents histograms showing the fre quency of occurrence of each dn for tm bands 2, 4 and 5 of austre braggerbreen for 1987 and 1988. the tm band 2 and tm band 4 histograms for 1987 display two distinct peaks which reflect the different surface reflectance of the ablation and accumulation zones of the glacier. the shape of the two histograms is similar, although the tm band 4 histogram is shifted towards smaller dns. this indicates that the near-infra-red reflectance (tm band 4) is lower than the visible reflectance (tm band 2). in 1988, however, the peaks are not as pronounced because the transition from the ablation zone t o the accumulation zone is indistinct. areas of low reflectance are present within the accumulation zone and the ela is located 440 m.a.s.1. at the end of the mass balance year in 1988 (hagen, pers. commun.). inter estingly, a marked cleft is also present in the 1988 histograms in such a way that some of the dns table 1. statistics for tm bands 2, 4 and 5 of austre b r ~ g gerbreen. landsat tm images were acquired on 7 august 1987 and 31 august 1988 tmz tm4 tm5 1987 1988 1987 1988 1987 1988 mean (dn) 98.22 54.43 76.62 46.58 7.00 13.72 maximum 147 97 135 98 66 29 minimum 26 31 18 22 2 4 std. dev. 25.51 12.72 26.05 14.63 5.48 4.95 are almost absent, especially in tm band 4. this cleft probably represents the division between snow and blue ice. if so, the histograms confirm the situation present in these two years: (1) less blue ice is exposed in 1987 than in 1988 (the left peak is smaller in the 1987 histograms) and (2) the ablation and accumulation zones show less variability in the frequency of occurrence of the dns and are better separated in 1987 (more dis tinct peaks with a larger interval in the 1987 histograms). the tm band 5 histograms display low dns for both years due to the very low reflectance of snow and ice at these wavelengths. austre braggerbreen and midre lovknbreen are divided into five height zones: 50-100 m, 100 200111, 200-300m, 3 0 0 4 0 0 m and >400m, respectively. variations in the surface reflectance as a function of altitude can be seen in table 2 and are displayed in fig. 8. the surface reflectance increases steadily as the altitude increases, except for the uppermost height zone of austre brag gerbreen (fig. 8). above about 400 m some areas of the glacier flatten out, delaying the downwards drainage of meltwater. consequently, the meltwater which percolates through the snow pack and down t o the surface of the glacier flows at a slow rate due to the gentle gradient. in some areas the meltwater drainage is hindered to such a degree that meltwater rises in the snow pack and even wets the surface. spots with low surface reflectance are therefore common in this height zone. satellite-derived surface albedo is shown in tables 3, 4, 5 and 6. as mentioned earlier, the calculation of albedo follows the procedure reported by markham & barker (1986) and tanrc et al. (1990). topographic effects are only con sidered by removing shaded areas. snow is regarded as an isotropic reflector. in situ measurements of the albedo of snow, ice and moraine fig. 9 shows the daily mean albedo (305nm 2800 nm) measured at austre braggerbreen at 300 m.a.s.1. from 16-28 august 1991. fig. 10 dis plays the shortwave albedo variations on four selected days. initially, e.g. on 16 august, the surface consisted of 30 cm wet snow with a grain size of 2-3 mm overlaying the glacier ice. gradu ally the snow melted and the surface charac teristics turned to a mixture of snow, water puddles and blue ice. this resulted in a pro summer reflectance of glaciers in svalbard 45 tm band 2 50 ' " i i 60 . tm band 2 50 4 0 ' 30 . 2 0 0 64 1 28 l o i !! 6 0 tm band 4 2 1987 :: 4 0 o 30 6 2 5 0 r 0 64 1 i 8 loi zw 1w t 0 150 1w 50 0 0 tm band 5 1987 tm band 5 1987 64 126 192 dn number 64 126 192 dn number !! 8 0 1 i tm band 4 1988 0 84 120 i92 tm band 5 200 150 0 64 128 192 dn n u m b e r fig. 7. histograms showing the frequency of occurrence of each dn for tm bands 2 . 4 and 5 of austre br~ggerbreen. landsat tm images were acquired on 7 august 1987 and on 31 august 1988. nounced drop in the surface albedo (fig. 9). on 24 august a smooth, slippery and wet blue ice surface was exposed. finally, fresh snow began to accumulate on the blue ice and the albedo increased again. fig. 9 clearly demonstrates how variable the albedo of the glacier can be during tabk 2. tm band 4 statistics for five height zones of austre brbggerbreen: 50-100 m. 100-200 m, 200-300 m. 3004!4 m and >400 m, respectively. the landsat tm image was recorded on 7 august 1987. zone i zone i 1 zone 111 zone iv zonc v (5w100m) (100-200 m) (200-300 m) (300-400 m) (>400 m) mean (dn) 25.98 42.85 68.19 80.80 78.32 maximum s4 77 132 167 115 minimum 18 21 29 27 29 std. dcv. s.ou 11.28 17.93 18.35 10.16 no. of pixels 253 1968 2938 1829 890 46 j-g. winther tm band 4 height zone 1 50-100 m 80 60 140 120 tm band 4 100 . height zone 2 80 . 100-200 m 60 . 4 0 1 0 . 0 , 0 64 128 102 tm band 4 200-300 m 100 height zone 3 t o ; 20 ll24l-j 128 192 0 64 140 120 tm band 4 height zone 4 1 300-400m .r 20 u 0 64 128 182 140 i 1 120 100 1 eo tm band 4 height zone 5 > 400 m 0 64 128 192 dn number fig. 8. histograms displaying the frequency of occurrence of each dn for tm band 4 for five different height zones on austre br0ggerbreen: 50-100 m, 100-200 m. 2 w 3 0 0 m, 300 400m and >400m, respectively. the landsat thl image was recorded on 7 august 1987. this time of year when both intensive snow melt and accumulation of fresh snow can occur. visible and near-infra-red spectral albedo measurements of clean snow (fresh snow as well as metamorphosed snow) and moraines were acquired in june 1992 using the portable se 590 spectrometer (fig. 11). the top of the snow pack consisted of about 4 cm of fresh-fallen snow on 2 june. underneath, the snow pack was composed of different layers of coarser snow which had previously undergone recrystallization (table 7). the fresh snow causes the high albedo seen in curve a (fig. 11). the albedo of snow is 0.988 at 372nm and remains larger than 0.95 up to 645 nm. here, the albedo reduction becomes more prominent and the snow albedo becomes 0.856 at 900nm. the average snow albedo between 372 and 900 nm is 0.941. curves b and c are from 9 june, after a week of on-going metamorphism in the snow pack. air temperatures were both below and above zero in this period causing slow and irregular melting. the surface snow grains grew and were rounded, and the characteristic grain size increased from less than 1 mm on 2 june to 2-3 mm on 9 june (table 7). on 9 june, the liquid water content was close to zero due to night-time freezing, creating a strong crust layer comprising the upper 9 cm of the snow cover. curve b is taken at 15:30 (local summer time) at the same site as curve a and under similar weather conditions (100% overcast) with mainly diffuse incoming radiation. curve b displays a general decrease in albedo compared to curve a (fig. 11). moreover, the decrease is more pronounced in the near-infra-red region where the albedo drops off quickly. visible sur face impurities were not seen on either 2 june or 9 june, and the albedo reduction is most probably caused by the increase in the snow grain size. curve c is taken under clear sky conditions at 13:30 (local summer time), two hours prior to curve b. there were no noticeable changes in the snow surface characteristics during the two hour period. two effects besides cloud conditions and instrumental errors might have contributed to a change in albedo: (1) the varying contribution of specular reflection from the snow surface with solar angle and (2) the metamorphism (recrys tallization on the surface and within the snow pack). regarding (l), the snow albedo increases as the solar elevation decreases because the first scattering event happens closer to the surface at low sun angles than at larger ones (dirmhirn & summer rejlectance of glaciers in svalbard 47 table 3. satellite-derived surface albedo for five height zones on austre breggerbreen recorded on 7 august 1987.. height tm band mneb 1 2 3 4 5 7 0.01 f 0.00 0.01 f 0.00 i: 50-100m 0.15t0.04c 0.17t0.04 0.16f0.03 0.14t0.03 11: 100-200111 0.26 f 0.06 0.29 f 0.06 0.27 f 0.05 0.24 t 0.06 0.01 f 0.00 0.01 f 0.00 111: 200-300m d 0.45f0.08 0.4ofo.08 0.39t0.10 o.olfo.01 o.olfo.01 iv: 300-40111 d 0.52f0.08 0.47f0.08 0.47zt0.10 o.olfo.01 0.01 f 0.02 v: >400m d 0.51 f 0.05 0.45 f 0.05 0.46 zt 0.05 0.01 f 0.00 0.01 f 0.01 a satellite data recorded at solar elevation, cx, = 26.8". sample size for zone i is nl = 253, nl, = 1968, nlll = 2938, nlv = 1829 and n, = 890. standard deviation. data saturation occurred. table 4 . satellite-derived surface albedo for five height zones on austre br~ggerbreen recorded on 31 august 1988'. height tm band zoneb 1 2 3 4 5 7 i: 50-100 m 0.20f 0.02' 0.24 f 0.02 0.21 f 0.02 0.21 * 0.02 0.02 f 0.00 0.01 f 0.00 11: 100-200m 0.28 f 0.03 0.31 f 0.03 0.28 f 0.03 0.31 f 0.04 0.03 f 0.01 0.02 2 0.01 111: 200-300 m 0.36 ? 0.04 0.42f0.04 0.38t0.05 0.43r0.06 0.06to.04 0.05?0.03 iv: 3 m m 0.45 f 0.05 0.52f0.06 0.48fo.w 0.54*0.09 0.09fo.04 0.08f0.04 v: >400m 0.44 f 0.03 0.49 f 0.04 0.43 ? 0.04 0.50 f 0.06 0.08 t 0.01 0.05 f 0.01 a satellite data recorded at solar elevation. cr, = 18.6". sample size for zone i is nl = 246, nll = 1497, nlll = 2695, nlv = 1366 and nv = 736. standard deviation. 1 0.9 0.8 0.7 0.6 2 0.5 4 0.4 0.3 0.2 0.1 0 '0 + + + +-snow + + mixture of snow, + thin layer of i + water and blue ice fresh fallen snow + + + + + 0 blue ice 0 910816 910818 910820 910822 910824 910826 910828 date fig. 9. daily mean albedo of austre br0ggerbreen at an elevation of 300 m.a.s.1. the data clearly demonstrates how the reflectance decreases as the surface character turns from snow to blue ice from 16-24 august. at the end of the period, fresh snow started to accumulate on the blue ice surface. in situ measurements were recorded by a kipp and zonen cm 7 albedometer with an effective wave length range of 300 to approximately 2500 nm. 48 j-g. winther 0.0 0.7 0.6 0.5 0.4 0.3 0.2 0.1 table 5. satellite-derived surface albedo for five height zones on mdre lovcnbreen recorded on 7 august 1987'. august 27 . ,********..** .... * .**.....**...* ..*.* * * ..***... height tm band zoneb 1 2 3 4 5 7 i: 50-100m 0.22 k 0.03' 0.21 k 0.02 0.18ko.02 0.14r0.02 0.0120.00 0.0120.00 11: 100-200m 0.26 k 0.04 0.28 k 0.05 0.23 2 0.05 0.20 k 0.06 0.01 f 0.00 0.00 * 0.00 ill: 200-300m 0.40 * 0.06 0.45 r 0.07 0.3920.07 0.38k0.09 o.olko.00 o.oliro.00 v: >400m d 0.56 k 0.06 0.51fo.07 0.53k0.08 o.olko.02 o.olko.01 a satellite data recorded at solar elevation, as = 26.8". iv: 3 w 0 0 m d 0.54 k 0.05 0.47 k 0.05 0.48 k 0.06 0.01 k 0.01 0.01 k 0.01 sample size for zone i is n, = 378, rill = 844, nlll = 1126, nlv = 958 and n, = 855. standard deviation. data saturation occurred. eaton 1975; carroll & fitch 1981; mcguffie & 34.0" at 13:30 and 31.6" at 15:30 (both local henderson-sellers 1985). thus, the chance for an summer time) at the measuring site on 9 june. electromagnetic wave to escape from the snow considering the small reduction in solar eleva pack without being absorbed is improved by low tion, a significant increase in albedo due to a incident angles. this effect on the albedo is symlowered solar angle is not likely (wiscombe & metric around local noon. the solar elevation was warren 1980). concerning the second con 0.0 . . . * ' * ... * * * * 0.7 ,,... . . * * * * * o.' i august 16 0.1 :::: o 1140 1240 11440 1% hour 0.8 0.7 0 o.6 3 0.4 ; 0.5 0.3 0.2 0.1 0 august 26 august 26 ***.. .***...**. . .******* .*.... ***... *.... 759 859 959 i059 1159 1250 1350 14% 1550 i . * . * * . . n i 759 859 959 i059 1159 1250 1350 14% 1550 hour 0.0 *,.*....*. **.......*****.*t*.*.***** ..... .... *, 759 859 959 1059 1159 1259 1358 1459 1559 hour 0.0 hour fig. 10. i n situ albedo measurements from austre br~iggerbreen (300m.a.s.l.) on 16, 24, 26 and 27 august 1991. the logging interval is 1omin. summer reflectance of glaciers in svalbard 49 d e i f i i i i i i table 6 . satellite-derived surface albedo for five height zones on midre lovenbreen recorded on 31 august 1988". height zoneh i: 5&100m 11: 100-200m ill: 200-3.300 m iv: 300-400 m v: >400m tm band 1 0.20 f 0.03' 0.28 f 0.03 0.38 f 0.03 0.47 f 0.05 0.51 f 0.06 2 3 4 5 7 0.22 f 0.03 0.19 f 0.02 0.19 f 0.03 0.02 f 0.00 0.01 f 0.00 0.03 f 0.01 0.30 f 0.04 0.26 f 0.04 0.28 r 0.04 0.04 f 0.01 0.41 f 0.03 0.36 f 0.03 0.41 f 0.05 0.06 f 0.01 0.05 2 0.01 0.51 f 0.06 0.47f0.07 0.54f0.09 0.0920.02 0.07f0.02 0.59 f 0.07 0.5420.07 0.65f0.10 0.1020.03 0.08f0.02 a satellite data recorded at solar elevation. n, = 18.6". ' sample size for zone i is nl = 473, nll = 762, nlll = 1057, nlv = 895 and n, = 463. standard deviation. 100 90 80 70 60 8 c1 5 50 = 40 30 20 10 0 h y q) 0 0 q d wavelength (nm) fig. 11. reflectance curves for (a) fresh snow on 2 june, 1992 (overcast), (b) coarse-grained snow at 15:30 local summer time on 9 june 1992 (overcast), (c) coarse-grained snow at 13:30 local summer time on 9 june (clear sky), (d), (e) and (f) moraines at the terminus of austre br~iggerbreen on 10 june 1992. note the increase in spectral albedo within a two-hour period on 9 june due to the change from clear sky to overcast weather conditions. all measurements were made at nadir viewing angles. tribution (2), the metamorphism of the snow pack is an irreversible process and normally results in a decrease of the albedo. a crust layer due to night-time freezing was registered all the time on 9 june. consequently, it seemed like the changes of snow surface characteristics due to meta morphism were small, at least during a period of only two hours. further, in this case, the two effects counteract each other. if effects from solar angle, metamorphism and the instrument are discounted, the increase in average albedo from 0.812 to 0.869 (i.e. 7 per cent) from 13:30 (curve c) to 15:30 (curve b) can most probably be attributed to the change from direct (curve c) to diffuse radiation (curve b). this because clouds absorb a higher portion of infra-red than visible radiation. thus, a rela tively high portion of the visible radiation reaches the ground under cloudy conditions. because the visible snow albedo is very high (>90%) com pared to the near-infra-red albedo (about 50%), an increase in surface albedo is to be expected when the weather turns from clear sky at 13 : 30 till complete overcast conditions at 15 : 30 (wendler & kelley 1988). curves d, e and f show spectral signatures for 50 j-g. winther n , m three different types of moraine found in the terminus area of austre braggerbreen on 10 june 1992. curve d displays spectral characteristics of stones with lengths between 5 and 40cm. the average albedo is 0.259. curve e is from a 2 4 cm thick layer of wet sand/silt overlaying the glacier ice. curve e has an average albedo of 0.104. finally, curve f represents an area of dry stones with lengths between 2 and 15cm and has an average albedo of 0.055. bidirectional reflectance of snow fig. 12 shows the spectral reflectance of snow for viewing angles 0" (nadir), 15", 30", 45" and 60" for viewing directions facing the sun, and 90" and 180" away from the sun. the reflectance curves from 9 june were acquired with clear sky conditions. reflectance values larger than 1 .o appear, especially for the largest viewing angles. off-nadir reflectance values >1.0 are reported to be quite common for dry snow (hall et al. 1992b) and are also published by dozier et al. (1988). this is because snow can reflect light specularly, and more light may be reflected than is incident upon the snow in one particular direction. measurements facing the sun on 9 june (fig. 12) display the largest anisotropy even though such anisotropy is seen in the scan sequences facing away from the sun as well. in fact, some specular reflection occur at all azimuth angles (dirmhirn & eaton 1975). on 9 june, the integrated albedo increases with 0.07 from nadir to 15" off-nadir in the viewing direction facing the sun while the increase is 0.04 from nadir to 15" off-nadir in the viewing direction facing 90" away from the sun. similarly, the increase from nadir to 45" off-nadir is 0.20 and 0.06 for the two viewing directions. the reflectance curves taken 180" away from the sun on 9 june are affected by shadows from the tripod where the spectrometer was fastened (fig. similar reflectance characteristic curves are dis played for 8 june (fig. 12). these curves were acquired during overcast weather and thus the incoming radiation was mainly diffuse. even dur ing overcast weather with diffuse incoming radi ation, the radiation scatters mostly in the forward direction (kanestram 1975). the effective solar elevation for overcast weather conditions (i.e. diffuse radiation) is normally estimated to be 40" (warren 1982). the integrated albedo increases 0.11,o.lo and 0.11 from nadir to 15" off-nadir for 12). summer reflectance of glaciers in svalbard 51 120 0 (111 100 80 7 0 90 '0 2 6 0 a 5 0 4 0 30 2 0 10 june 8 , sun ando 33.9' facing the sw a so w: 15 0 jum a. sun m#o i 34.0' faanp &away fmm ule sun 1 30 40 1 e n 5 0 40 30 2 0 10 :i, , , , , , , i o 3 w 400 500 wo 700 bw 900 jun, 9. sun an$e i 29.5' fmng 9 0 4 w a y lrom the sun i t 1 im 90 e n 70 e n 5 0 40 1 2 0 , t 0 70 jum 8. run ande w.2 ' facing 18@away imm h e sun '1 , , , , , , , 10 o 3 0 0 400 500 wo 700 800 boo wavelength (nm) 80 70 20 10 1 2 0 , i 110 80 70 !! 10 300 4m 500 0 700 800 900 wavelength (nm) fig. 12. reflectance curves of snow measured at viewing angles 0" (nadir). 15". 30", 45" and 60" for viewing directions facing the sun, and 90" and 180" away from the sun o n 8 june and 9 june 1992. measurements from 8 june werc taken on austre breggerbreen at 175 m.a.s.1. in overcast weather while the reflectance curves from 9 june were obtained during clear sky conditions o n a snow covered site downstream from the terminus of austre breggerbreen (15 m.a.s.1.). the viewing direction facing the sun, 90' and 180" away from the sun, respectively. similarly, the increase in albedo is 0.20, 0.20 and 0.19 from nadir to 45" off-nadir. however, because of the overcast weather, this represents a situation where landsat tm images are useless for studies of surface characteristics. fig. 13 displays the spectral reflectance of snow from 2-3, 8 and 10 june. on 2 june and 3 june, the surface consists of freshly fallen snow with 52 j-g. winther m 70 6 0 5 0 4 4 30 2 0 to characteristic grain size less than 1 mm (table 7). the snow on 8 june and 10 june was considerably more metamorphosed with larger snow grains (table 7). this change in snow grain size should have little effect on the visible albedo but a larger effect on the near-infra-red albedo (wiscombe & warren 1980; warren 1982). in accordance with the theory, the curves have a similar slope in the visible region while the drop in the near-infra-red albedo is more pronounced on 8 june and 10 june than on 2 june and 3 june (fig. 13). a possible source of error is that the measurements from 2 june and 3 june are facing 180" away from the sun while the curves from 8 june and 10 june are facing towards the sun. however, the measure ments presented in fig. 12 demonstrate that a change in azimuth viewing direction mainly leads to a parallel displacement and not an alteration jva 2. sun uwje i 32.5' facng t80'awry hom the sun i-" i i 100 9 0 1m l 110 100 9 0 0 eq i! 70 june& amamje325' fumq the s m 20 10 o x ~ ) 4 ~ ) 500 bm) 700 800 em 0 3 70 g 6 0 a m j v a 10. sun ando i 30.9' h e + th. 6m 'i, , , , , , , 10 0 3 0 0 4 m ) 5 0 0 6 0 0 m 0 8 0 0 e m wavelength (nm) m 0 5 0 4 4 30 2 0 10 of the shape and slope of the reflectance curves. this is also seen in the work reported by dozier et al. (1988) it thus seems likely that the drop in the near-infrared albedo on 8 june and 10 june is caused by an increase in snow grain size (fig. 13). table 8 presents the integrated albedo for all the curves shown in figs. 12 and 13. the increase of albedo (in per cent) due to the bidirectional reflectance of snow is 8, 15, 19 and 26 per cent when the viewing angles are 15', 30", 45" and w, respectively. in studies where satellite images are used for absolute calculations of surface reflec tance, the specular reflection of snow crystals must be accounted for. however, the specular properties of the snow can vary considerably dur ing a short time and it may be difficult to estimate the effect of bidirectional reflectance at a given j u * 3. sun m#e 29.3' fumg 180'aw.y hum th. sun 1 i fig. 13. spectral reflectance of snow from 2, 3. 8 and 10 june. on 2 june and 3 june the surface consisted of fresh fallen snow with grain sizes less than 1 mm. the snow o n 8 june and 10 june was considerably more metamorphosed with a characteristic snow grain size of 1-5 mm. the decrease in the near-infra-red albedo is more pronounced in the curves taken o n 8 june and 10 june, reflecting the effect of snow grain size on the spectral albedo. summer reflectance of glaciers in svalbard 53 table 8. the table presents the integrated albedo of snow from measurements taken on 2, 3.8, 9 and 10 june (figs. 12 and 13). the increase (in percent) relative to the albedo at nadir due to bidirectional reflectance of snow is given for viewing angles 15", 30". 45" and 60" off-nadir for (1) all measurements, (2) measurements facing the sun (clear sky) and (3) measurements facing 90" away from the sun (clear sky). the measurements include snow in various degrees of metamorphosis. nadir 15" 30" 45" albedo, all measurements 86.65 93.84 99.65 103.24 increase of albedo (%) 8.30 15.01 19.15 albedo, facing the sun, clear sky 80.22 86.46 94.32 100.25 increase of albedo (a) 7.79 17.58 24.98 albedo, 90" away from the sun. clear sky 87.22 91.57 94.76 92.88 increase of albedo (%) 4.99 8.64 6.49 60" 109.09 25.90 115.27 43.70 96.18 10.27 point of time without reference ground truth measurements. conclusions the study uses both satellite-derived and in situ measurements to indicate the large range of sur face reflectance which may be present on a glacier, especially at the end of the mass balance year. the variations i n glacier albedo are shown to be large in several respects: (1) from one year to another, (2) at different areas of the glacier at one point of time and (3) on one fixed location during a period of a few days. the albedo affects the energy absorption of the glacier and thus its mass balance as well as the earth-atmosphere energy balance. consequently, the monitoring of glacier reflectance is important for local, regional and global energy exchange calculations. the near-infra-red snow albedo is sensitive to changes in characteristic snow grain size. spectral measurements show a distinct drop in the near infra-red albedo as the snow metamorphoses, i.e. the grain size increases. the visible albedo is little affected by the variation of grain size. clouds affect the snow albedo by introducing a spectral shift to the incoming radiation. it is shown that the integrated snow albedo (370-900 nm) increases by 7 % due to the change from clear sky to overcast weather. with respect to climate change, there are concerns that changes in the cloud conditions such as type, height and dis tribution may occur if the climate changes. as seen above, an increased amount of cloud cover age can in isolation give a negative feedback on the snow surface (shortwave) energy exchange system by increasing the snow albedo. metamorphosed snow is an anisotropic reflec tor and reflects light specularly. thus, more light may be reflected than is incident upon the snow in one particular direction. the increases in albedo relative to the nadir albedo for the viewing angles 15", 30", 45" and 60" for measurements facing the sun (clear sky) were calculated to be 8, 18,25 and 44%, respectively (table 8). similarly, for all measured directions, the increase in albedo was computed to be 8,15,19 and 26%. consequently, landsat tm derived snow reflectance for meta morphosed snow in rugged terrain cannot be con sidered absolute albedo values. a digital terrain model of a study area is needed to correct for the effects introduced by the topography and the anisotropic snow reflectance. finally, the effect of anisotropic snow reflectance varies with the state of the snow and must be updated t o obtain accurate corrections at a given point of time. this can be done by reference ground truth measure ments, for example. acknowledgements. -the author would like t o thank 0. u v o l l , a. l0vou and 0. bruland at the norwegian institute of tech nology and k. sand at the sintef norwegian hydrotechnical laboratory for valuable assistance during the field work in 1991 and 1992. further, acknowledgements are addressed t o j . 0. hagen at the norwegian polar institute for providing essential data and j. maedel at the university of british colombia for substantial help and guidance during the processing of the satellite data. the norwegian national committee for hydrology is acknowledged for their financial support. references benson, c. s. 1959: physical investigations on the snow and firn of northwest greenland: 1952, 1953 and 1954. sipre res. rep. 26. benson, c. s. 1967: polar regions snow cover. pp. 103s1063 in oura, h. (ed.): physics of snow and ice. international conference of low temperature science 1964 proceedings. vol. i . part 2 . sapporo, hokkaido university. 54 j-g. winther benson, c. s . & motyka, r. j. 1979: glacier-volcano inter actions on mt. wrangell, alaska. university of alaska, fair banks. geophysical institute. annual report 1977-78. pp. 1-25. bryazgin. n . n . & koptev, a. p. 1%9: 0 spektral'nom al'bedo snezhnoledyanogo pokrova (spectral albedo of a snow ice cover). probtemy arktiki i antarktiki 31, 79-83. carroll, j . j . & fitch, b. w. 1981: dependencc of snow albedo on solar elevation and cloudiness at the south pole. j. geophys. res. 86,5271-5276. choudhury, b. j. & chang, a. t. c. 1979: two-stream theory of reflectance of snow. ieee trans. geosci. and remote sensing 1 7 , 6 3 4 8 . colbeck, s . , akitaya, e., armstrong, r., gubler, h., lafeu ilk, j., lied, k., mcclung, d. & morris, e. 1985: the international classijication for seasonal snow on the ground. issued by the international commission on snow and ice of the international association of scientific hydrology; co issued by thc international glaciological society. 23 pp. dirmhirn, i. & eaton, f. 0. 1975: some characteristics of the albedo of snow. j . appl. meteorol. 14, 375-379. dozier, j . 1984 snow reflectance from lendsat-4 thematic mapper. ieee trans. geosci. and remote sensing ge 22,323328. dozier, j. 1985: spectral signature of snow in visible and near infrared wavelengths. proc. 3rd internat. colloq. spectral signatures of objects in remote sensing, paris, esa sp-247. 437-442. dozier, j . 1989: spectral signature of alpine snow cover from the landsat thematic mapper. remote sensing enoiron. 28, 9-22. dozier, j., schneider. s . r. & mcginnis, d. f. 1981: effect of grain size and snowpack water equivalence on visible and near-infrared satellite observations of snow. water resources res. 17, 121s1221. dozier, j . , davis, r. e . , chang, a. t. c. & brown k. 1988: the spectral bidirectional reflectance of snow. proc. 4th internal. colloq. spectral signatures of objects in remote sensing, france, esa sp-287. 87-92. hagen, j. 0. & liestbi, 0. 1990: long-term glacier mass balance investigations in svalbard, 1950-88. ann. glaciol. hagen, j . 0.. korsen, 0. m. & vatne, g. 1991: drainage pattern in a subpolar glacier: br~ggerbreen, svalbard. norwegian natl. comm. hydrol. rep. 23, 121-131. hall, d. k. & ormsby, j. p. 1983: use of seasat synthetic aperture radar and landsat multispectral scanner sub system data for alaska glaciology studies. j . geophys. res. hall, d. k., ormsby, j. p., bindschadler, r. a . & sidda lingaiah, h. 1987: characterization of snow and ice reflec tance zones on glaciers using landsat thematic mapper data. ann. glaciol. 9. 104-108. hall, d. k., chang, a. t. c. & siddalingaiah, h. 1988: reflec tances of glaciers as calculated using landsat-5 thematic mapper data. remote sensing enoiron. 25, 311-321. hall, d. k., chang, a. t. c., foster, j. l., benson, c. s. & kovalick, w. m. 1989: comparison of in situ and landsat derived reflectance of alaskan glaciers. remote sensing environ. 28, 23-31. hall, d. k., bindschadler, r. a., foster, j. l., chang, a. t. c. & siddalingaiah. h. 1990: comparison of in situ and satellite-derived reflectances of forbindels glacier, green land. int. 1. remote sensing 11(3), 49s504. 14, 102-106. 88(c3), 1597-1607. hall, d. k., williams, r. s. & bayr, k. j. 1992a: glacier recession in iceland and austria. eos trans. a m . geophys. union 73(12), 129, 135, 141. hall, d. k., foster, j. l. & chang, a. t. c. 1992b: reflectancc of snow as measured in situ and from space in sub-arctic areas in canada and alaska. ieee trans. geosci. and remote sensing 30(3), 634-637. holben, b. n . &justice, c. 0. 1979: evaluation and modeling of the topographic effect on the spectral response from nadir pointing sensors. nasa tm 80305, goddard space flight center, greenbelt, maryland. kanestrem, 1. 1975: striling i atmosfzercn (radiation in the atmosphere). report. geophysical institute, university of liest01,o. 1977: pingos, springs and permafrost in spitsbergen. norsk polarinst. arbok 1975.7-29. lillesand, t. m. & kiefer. r. 1987: remote sensing and image interpretation. 2nd ed. john wiley & sons. new york. 721 pp. markham, b. l. & barker, j. l. 1986: landsat mss and tm post-calibration dynamic ranges, exoatmospheric reflectances and at-satellite temperatures. eosa t technical notes i , 3-8. mcguffie, k. & henderson-sellers, a. 1985: the diurnal hys teresis of snow albedo. 1. glaciol. 31(108), 188-189. miiller, f. 1%2: zonation in the accumulation area of the glaciersof axel heiberg island, n.w.t., canada. j. glaciol. orheim. 0. & lucchitta, b. k. 1988: numerical analysis of landsat thematic mapper images of antarctica: surface tem peratures and physical properties. ann. glaciol. i i , 1 w 1 2 0 . parrot, j. f., lyberis, n., lefauconnier, b. & manby, g. 1993: spot multispeetral data and digital terrain model for the analysis of ice-snow fields on arctic glaciers. int. j. remote sensing 14(3), 425440. paterson. w. s . b. 1981: the physics of glaciers. 2nd ed. pergamon press, new york. 380 pp. proy, c., tanre, d. & deschamps, p. y. 1989: evaluation of topographic effects i n remotely sensed data. remote sensing enoiron. 30, 21-32. sand, k. berntsen, e., hagen, j . 0. & repp, k. 1991: climate related research in svalbard. norwegian nut. comm. hydrol. rep. 23. 203-217. schytt, v. 1981: the net balance of storglaciaren, kebnekaise, sweden, related to the height of the equilibrium line and to theheightofthe5m)mbsurface. geogr. ann. 6 3 a ( 3 4 ) , 2 1 s 223. steffen, k. 1987: bidirectional reflectances of snow, in large scale effects of seasonal snow cover. pp. 415-425 in goodison, b. e., barry, r. g. & dozier, j. (eds.): proceedings of the iahs symposium, canada. tanrc, d., deroo, c., duhaut, p., herman, m., morcrette, j. j., perbos, j. & deschamps, p. y. 1990: description of a computer code to simulate the satellite signal in the solar spectrum: the 5s code. int. 1. remote sensing 11, 659-668. wakahama, g., kuroiwa, d.. hasemi, t. & benson, c . s . 1976: field observations and experimental and theoretical studies on the superimposed ice of mccall glacier, alaska. i . glaciol. 16(74), 135-149. warren. s. g. 1982: optical properties of snow. reo. geophys. space phys. 20(1). 67-89. warren. s. g. & wiscombe, w. j. 1985: dirty snow after nuclear war. nahue 313, 467-470. wendler, g . & kelley, j. 1988: on the albedo of snow in oslo, 204 pp. 4(33), 302-311. antarctica: a contribution to i.a.g.o. 1. glaciol. 34. 19 25. williams, r. s., hall, d. k. & benson, c. s. 1991: analysis of glacier facies using satellite techniques. j. glaciol. 37(125), 12&128. wiscombe, w. j. & warren, s. g. 1980: a model for the spectral albedo of snow. i: pure snow. j. atmos. sci. 37, young, g . j . 1981: the mass balance of peyto glacier, alberta, 27 12-2133. canada, 1965 to 1978. arct. alp. res. 13(3), 307-318. summer reflectance of glaciers in sualbard 55 zeng, q., cao, m., feng, x., liang, f., chen, x. & sheng, w. 1984: a study of spectral reflection characteristics for snow, ice and water in the north of china. hydrological applications of remote sensing and remote data trans mission. proceedings of the hamburg symposium. iahs pub lication no. 145, 451-462. bstrem, g . 1975: erts data in glaciology: a n effort to monitor glacier mass balance from satellite imagery. 1. giacio115(73), 40w15. flow speed and calving rate of kongsbreen glacier, svalbard, using spot images bernard lefauconnier. jon ove hagen and jean paul rudant lefauconnier, b., hagen, j . 0. & rudant, j . p. 1994: flow speed and calving rate of kongsbreen glacier, svalbard, using spot images. polar research 59-65. kongsbreen. a tide-water glacier located in kongsfjorden. is the most active calving glacier in svalbard. three spot images are used to determine its flow speed and calving rate. the position of fourteen reference points was determined on the coast or mountain sides, and the changes in position of 144 characteristic features on the glacier surface were calculated. the obtained speed profiles are consistent with the findings from previous works from 1962-64 and 198s86. when comparing the obtained longitudinal profile to the data from 1962-64. it is found that the flow velocity at a given distance from the front has been nearly constant. the results from the spot images analysis are completed by using existing topographic works. the present study shows that spot images (panchromatic as well as multichannel), recorded with a periodicity of one year, can be used to determine precisely the annual flow speed and calving rate of active glaciers such as kongsbrccn. images recorded with a periodicity of two, three or four weeks can allow identical determination on tide-water glaciers during a surging active phase. b . lefauconnier (laboratoire de glaciologie er geophysique de i'enuironnement, bp 96, 38402 saint martin d'hpres, cedex, france) and j . 0. hagen, norsk polarinsrirurt, middelrhunsgare 29, p . o . box 5072 majorstua. n-0301 oslo, norway; j . p. rudant, laboraroire de gkologie, geomorphologie structurale er telkdetection, uniuersiti pierre el marie curie. paris v i , 4 place jussieu, 75252 paris cedex os, france. introduction kongsbreen is a tide-water front of a glacier com plex calving in kongsfjorden (79'n, 12"e) (fig. 1). in this study, the main front and ice-stream located to the south of collethogda (see fig. 2) are considered. the studied calving tongue is formed by two joined ice streams, kongsvegen and kronebreen. kongsvegen is a glacier with an area of 100 km2, and kronebreen is an outlet of isachsenfonna, holtedahlfonna and infantfonna, three accumulation ice fields with a total area of 525 km2. the lamont expedition report (lamont 1876) reveals that kronebreen experienced an important surge in 1869 or in the previous year. the following retreat (more than 4 km) was inter rupted by a surge (revealed by aerial photographs from 1948) of kongsvegen which advanced about 1.5 km into the sea. since then, the glacier front has been continually retreating for more than 4 km. the changes in front position are described by lefauconnier (1987) and liestd (1988). today, referring to the classification used by dowdeswell(1989), kongsbreen is in a quiescent period between surges; however, it still remains the most active tide-water glacier in svalbard. its tide-water tongue is partially subjected to buoy ancy along about 7 km (lefauconnier 1987) and numerous crevasses are still visible at 17 km from the front. the aim of the present work is to use available spot images from 1986 to measure the change in position of characteristic features on the glacier surface, and then, to calculate row velocity, retreat of the front and calving rate. comparison with previous topographic (photogrammetry) works carried out in the period 1962-65 by d.d.r. expeditions (pillewizer 1967; voigt 1969) and in the period 1983-86 by lefauconnier (1987) allows the study of the change in the glacier activity from 1962 to 1986. data sources and method three spot images from 1986 were used, two multichannel images from 23 may and 7 sep tember and one panchromatic image from the 8 60 b . lefauconnier et al. august 1986. on the rock sides, the positions of 14 reference points were determined. as numerous crevasses are visible on the surface, diverse markers are identifiable on two successive images. two methods were used to measure the change in position of characteristic features: (1) a software program was used which combines two images at the same scale with superposition of the reference points. the displacement of characteristic features on the glacier surface was then obtained by measuring the difference of coordinates of each feature in the number of pixels; (2) slide projections of two successive images were utilised, separately side to side or superposed, to find the largest number of patterns visible on the two images. the two positions of every characteristic feature were then plotted on the same map and the displacement measured. fig. 1. location of the studied area. the latter method was used primarily t o control the result from digitalisation and it was, in fact, the more effective method. the large view on slide projections allowed the finding of about three times more points than from the computing method. to prevent a systematic error due to the size of the larger pixel (20m on the multichannel image), the displacement taken into account cor responds to the mean displacement of 3 to 6 points of a particular feature. the measurements were repeated several times to also prevent any poss ible error in the point determination. as an example, repeated measurements of the dis placement of the most remarkable crevasse near colleth~gda diverged by no more than 6% from the mean value. fig. 2 shows some vector plots which are representative of mean velocity values flow speed and calving rate of kongsbreen glacier, svalbard, using spot images 61 defined as above. figs. 3 and 4 give the transverse velocity profiles for locations which correspond to mean values of all points plotted in a 400m wide zone along the profile. the multichannel image from the 23 may was recorded at a time when the snow cover was maximum and thus prevents the finding of fea tures at the ice surface between crevasses. the low sun elevation and the different illumination angles between two successive images causes a change in the illuminated and shaded zone around each feature. it has thus only been possible to plot 28 common points on the images from both 23 may and 8 august, while 144 identical marks were noted on the two images from 8 august and 7 september. results and comparison with previous work surface velocity the highest speed values are found along a longi tudinal axis about 2.5 km from the south side of collethogda. the three transverse profiles p1, p2, fig. 2. tongue of kongsbreen. spot panchromatic image from the 8/08/1986. front positions are successively from the 27/06/ 1962, the 08/07/1983 and 22/08/1983. the 23/05/1986, 8/08/1986 and 07/09/1986. f, h . g , p1, f'2, p3 are location of profiles presented in figs. 3 and 5 . e-s is the location of a marine echo-sounding profile carried out in 1986. m l and m2 are medial moraines. longitudinal profiles presented in fig. 4 are located along m l . 62 b. lefauconnier et al. and p3 (see fig. 3 and location in fig. 2) show a declining speed from this axis towards the sides where there is no measurable movement. longi tudinal profiles (fig. 4) indicate a slightly increas ing velocity towards the front. during the period 8 august 7 september, the velocities were 1.7m/day at 2.4 km from the front, 2m/day at 1.5 km and 2.4m/day at the front. a few points plotted in may, close to the profile p2, indicate a value of 3-3.1 m/day between 23 may and 8 august against about 2 m/day between the 8 august and the 7 september. this determination agrees with the change in the velocity throughout the year (see below). otherwise, all presented results are consistent with results from previous works. measurements of surface velocities were made over a one year period in 1964-65 (pillewizer et al. 1967; voigt 1969). a nearly constant flow velocity was found from october to mid-june and an increase by a factor of about two occurred at the end of june; the velocity then declined at the end of july. in august the value was just slightly above the annual average, and i n september the velocity declined drastically t o half of the mean annual value. at the most active part of the front, a maximum speed of 4.5 m/day was recorded in july and the mean annual velocity was 2.15m/ day. the ice flow speed is related to the start of the ablation period, and temporary maxima are due to an increase of the water pressure in sub glacial channels (lliboutry 1965; pillewizer et al. i t a fig. 3. velocity transverse profiles. all profiles are seen fronting the ice how. the 0 km on the abscissa corresponds to the contact between the ice and collcth6gda (see fig. 2). in a, circles are velocities a 3 between the 8/ox and 7/ a b w/1986 as defined in the d d tcxt. p l ( a s ) =velocity d d a profile at the front hctween the 8/ox and the 7/w/1986; pl(y) = estimated annual velocity profile at the front. i n b . circles are velocitics hctwccn the 8/08 and x/ 09/1986, triangles arc velocities between the 231 05/1986 and the x/ox/ 1986. pi and p2 arc velocity profiles between the 8/08 and the 7/w/ 1986. i n c, profiles recorded by the d.d.r. expeditions, designation of profiles arc retained. f = front-querprofilen, f1 (27/06-30/06/1964); h = haupt-querprofil (28/07 1/08/1964); g = grense querprofil (28/07-1/08/ $ 2 a 2 a * 0 i z 3 (b) a 4 c (28/07-13/08/1962). f2 '\. 0 i z 3 4 (hm) 1964). flow speed and calving rate of kongsbreen glacier, svalbard, using spot images 63 3 1 'b s! 0 1 2 3 4 5 6 7 8 fig. 4. longitudinal velocity profiles. the origin on the distance axis is the confluence between kongsvegen and kronebreen. a and b = velocities along an axis located between the moraines m l and m2 (see fig. 2). a. in 1964 from d . d . r . expeditions; b. between 1962 and 1979 from lefauconnier 1987; c . between the 8/08 and the 7/09/1986 from the present work. dates of front positions fi: 1964. d 9m) m: 1979. f3: 1986. f3 f2 f1 1967; vivet & lliboutry 1978). on the other hand, the period with maximum flow speed may change from year to year but probably by no more than two or three weeks. in july 1986, at the most active part of the front, mean velocities were 4.33 m, 4.01 m and 3.80m/day during the periods 8-14, 14-23 and 23-29 july respectively (lefauconnier 1987). the same author, using aerial photographs and sat ellite images, found a fairly constant mean annual velocity around 2.15 m/day for the whole period 1964-79. all these velocities correspond with the velocities obtained by pillewizer et al. (1967) and those mentioned above. the velocity profiles obtained from the present work may be compared with the profiles reported by the d.d.r. expedition. the 1986 front profile, noted pl(a-s) in fig. 3, presents a shape similar to f1 and f2, front profiles from 1962 and 1964. the transverse profiles p2 and p3, located at 1.5 and 2.4 km respectively from the 1986 front, present a shape identical to the profile h located about 1.7 km from the 1964 front. the profile g , about 5 km from the 1964 front, is not comparable to any other profile, even though it is located very close to the profile p3. the d.d.r. profiles (see f1, f2, h and g) were used by voigt (1969) to study and define the modes of the flow at the glacier tongue of kongsbreen. these modes have been maintained along the discussed period. the longitudinal profiles (fig. 4) located along a medial moraine (see m l in fig. 2) also present a comparable shape. altogether this information shows that the velocity in one point is directly the ablation period, the velocity between 8 august and 7 september is logically slightly greater than the mean annual velocity. the mean annual velocity at the front was constant between 1964 and 1979. it may thus be assumed that the mean annual velocity at the front in 1986 was very close to the constant value of 2.15m/day. the annual velocity profile at the front (pl(y) in fig. 3) may be extrapolated from the profile during the period 8 august-7 september (pl(a-s) in fig. 3). calving rate the front positions in may, august and sep tember 1986, and thus the annual retreat, were determined from the three spot images. lefau connier (1987) carried out echo-soundings and topographical work during the period 1983-86. using photogrammetry, front positions and alti tude of the ice were determined. moreover, due to the retreat of the front, it was possible in 1986 to carry out one echo-sounding at a location corresponding to the 1983 front position (fig. 2); thus the bathymetry close t o the front was determined as well as the ice thickness. in the three years 1983-86, the change in ice thickness (combination of a possible increase due t o the rapid ice flow and a decrease due to the melting) may be considered as negligible. in one year, the linear calving corresponds to the flow velocity at the front plus the retreat of 64 b . lefauconnier er al. fig. 5. linear calving: a . ice thickness; b. retreat of the front; c . linear calving (retreat of the front plus annual ice flow at the front). the front (fig. 5). this linear calving is zero along both sides where the ice is stagnant or nearly stagnant, and reaches a maximum value close to 1100 m in the most active part. the measured ice thickness at the front varies from 45 up to 120 m; the total annual calving is then 0.25 km3 per year. this is a maximum value since the volume of crevasses is not taken into account. this is also the highest present calving rate registered in svalbard for a glacier during the quiescent period between surging active phases. discussion and conclusion the combination of one panchromatic and two multichannel spot images from may, august and september 1986 allowed surface velocities measurement at the tongue of kongsbreen. the accuracy of the measurements is difficult to esti mate due t o the use of multichannel images with a pixel of 20 m resolution and the relatively limited displacement of a number of surface features due to the close dates of recording. the present find ings are consistent with the results from previous topographic works. because the good pres ervation of a number of features at the glacier surface during summer which is the most active period, there is no doubt that some patterns are also preserved from year to year. for example, one of the most remarkable crevasses along col lethggda was still observed in the field in 1987. the study shows, then, that multichannel as well as panchromatic spot images with a recording interval of one year will permit determination of annual flow speed and calving rate of active calv ing glaciers in svalbard. moreover, the use of panchromatic images alone will permit carrying out such work on less active svalbard glaciers, and the use of images recorded with a periodicity of two, three or four weeks will allow identical determination on tide-water glaciers during a surge. while the front has been permanently retreating, the velocity in one point, at a given distance from the front, was constant during the entire period 1964-86. the velocity is between zero and 2.15 m/day or zero and 785 m/year, and the annual calvingis 0.25 km3. since the beginning of balance measurements in 1987, the net balance of kongsvegen has been slightly positive (hagen & liest01 1990). this is due to the weak calving of this glacier as its flow is blocked by kronebreen. the main stream. the balance at the surface of kronebreen, taking into account the accumu lation and the ablation by melting (i.e., without the calving) has been recently estimated (lefau connier et al. in press). the balance at the glacier flow speed and calving rate of kongsbreen glacier, svalbard, using spot images 65 surface was b = + 0.12 m in water equivalent dur ing the period 1986-1991. when introducing the calving, the net balance was bn = 0.13 m w.eq. the front of kongsbreen retreats between zero and 300/year at an average close to 200 m/year. within a few years, due to the present retreat, the length of the tongue subjected to buoyancy will be reduced; the flow velocity and the calving will also decrease. finally, the glacier will tend toward a positive balance; the ice flow will not compensate the surplus of accumulation and the glacier will start a building up which can initiate a new surge. due to the present climate, accord ing to the study by lefauconnier and hagen (1991), a possible new surge of kongsbreen will be of a lesser scale than the 1869 surge. references dowdeswell, j. a. 1989: on the nature of svalbard icebergs. 1. glaciol. 35 (120). 224-234. hagen, j . 0. & liestel, 0. 1990: long term mass-balance investigation in svalbard, 1950-1988. symposium on ice and climate, seattle 21-25 august 1989. ann. glaciol. 14, 102 106. lamont, j. 1876: yarching in the arcric seas or notes of five voyages of sport and discovery in rhe neighbourhood of spirs bergen and nouaya zemlya. w. livesay, m. d . , london. 387 pp. lefauconnier, b. 1987: fluctuation glaciaires dans l e kongsfjord, 79"n. spitsbergen, svalbard; analyse et con sbquences. thbse, universitc de grenoble, 1987. lefauconnier, b. & hagen, j. 0. 1991: surging and calving glaciers in eastern svalbard. norsk polarinsf. medd. 116. lefauconnier, b., vallon, m., dowdeswell, j., hagen, j . 0.. pinglot. j . f. & pourchet, m.: global balance of spitsbergen ice mass and prediction of its change due to climatic change. epoc 0035 scientific reporr (in press). liestel, 0. 1988. the glaciers i n kongsfjord area, spitsbergen. norsk geogr. tiddskr. 42, 231-238. lliboutry l. 1965. trait6 de glaciologie, t o m e 2 . masson, paris. pillewizer, w. et al. 1967: die wissenschaftlichen ergebnisse der deutschen spitsbergenexpedition 1964-65. geod. geoph. veroff. r.11, h 12. berlin 1967. vivet, r. & lliboutry, l. 1978: vitesse et intensite de vclage au front du kongsbre vers le ler aoht 1963. zeitschrifr f u r gletscherkunde und glarialgeologie bk 14, hi. 27-34. voigt, u. 1969: ergebnisse der bewegungsmessungen an kongsvegen und kronebree. wissenschaftlichen ergebnisse der deutschen spitsbergenexpedition 1964-65. geod. geoph. verofi r.111, h 9 . berlin 1969. coastal morpho-stratigraphy and holocene relative sea level changes at tuapaat, southeastern disko island, central west greenland morten rasch and niels nielsen rasch. m . & nielsen, n . 1995: coastal morpho-stratigraphy and holocene relative sea level changes at tuapaat, southeastern disko island, central west greenland. polar research 1 4 ( 3 ) , 277-289. the geomorphology of a coarse clastic coastal landscape at tuapaat (69"24'n 52"36'w), southeastern disko island, central west greenland, is described, and a coastal morpho-stratigraphy of the landscape is constructed. ''c ages o n marine shells. whale bones, peat and gyttja are used to construct relative sea level changes throughout the holocene. the emergence of se disko island occurred in the early part of the holocene. the holocene marine limit is situated ca. 80m a.s.1. between 4.7 and 1.0 ka bp. the relatlve sea level approached the present sea level and it h d s probably been below present sea level between 4.7 ka bp and the present. the morpho-stratigraphy in the lowest part of the coastal landscape at tuapaat suggests a complex late holocene relative sea level history which includes at least 3-4 transgressions during the last ca. 2.5 ka. morten rasch, arctic station. unioersity of copenhagen, dk-3953 godhauti. greenland; niels nielsen, institute of geography, university of copenhagen. (aster voldgade 10. dk-1350 copenhagen k , denmark. introduction present knowledge about late holocene relative sea level (rsl) changes in west greenland is very limited. the glacio-isostatic rebound fol lowing the wisconsinanfweichselian glaciation has been documented by several emergence curves representing local regions (weidick 1972b; kelly 1985; funder 1989). from these curves it is well established that the rsl approached the present sea level between ca. 3 and 4 ka bp. only scattered information is available today gbout the rsl changes that occurred in the period from 3 4 ka bp to the beginning of the present century, when tidal observations were initiated. however, it is well established that the rsl in some parts of west greenland has been below the present sea level during the last ca. 3 ka, and that trans gression(s) have occurred within the present mil lennia (kelly 1980, 1985; funder 1989; weidick 1993; rasch & nielsen 1994; rasch et al. in press). the main objective of this study is to contribute to a greater understanding of late holocene rsl changes in west greenland. special attention is given to rsl changes within the last millennia. both traditional and new methods have been applied in the investigation. an age-altitude dia gram based on holocene dates from southeastern disko island has been constructed. and the chronological sequence of coastal landforms (the coastal morpho-stratigraphy) in a coarse clastic coastal landscape at tuapaat (69"24'n 52"36'w) on the southern coast of disko island has been studied. in coarse clastic coastal landscapes, results of rsl changes are easily observed because regressions lead t o repeated simple beach ridge (swash ridge) formations, while trans gressions lead to the formation of either washover ridges (transgressive barriers) or coastal cliffs (carter & orford 1984; tanner 1988; rasch & nielsen 1994). as a result. individual landforms in a coarse clastic coastal landscape show evidence of the course of the rsl at the time of their origin, and the entire landscape represents a chronologically arranged archive of former rsl changes. physical setting disko island is situated in disko bugt, central west greenland, between 69'15" and 70"20'n and between 51"50'w and 55"oo'w (fig. 1). the climate is polar maritime. the mean annual tem perature in the town, qeqertarsuaq, southeastern disko island, is about -4°c and the mean annual precipitation varies between 100 and 500 mm (danish meteorological institute 1962-1985). the island lies within the zone of continuous 278 m . rasch & n . nielsen s t r a i t flg. 1 . disko island. old danish names of towns are 1 given in brackets. permafrost, and at present approximately 20% of disko island is glacierised (humlum 1988). the wave climate on southern disko island is characterised by wind waves from the east caused by katabatic winds blowing off the inland ice and by swell from the southwest and west caused by cyclones i n baffin bay. the net littoral drift is dominated by swell impact and is directed towards the east. the sea surrounding disko island is ice covered from mid-january to mid-april, and the shores of disko island are affected by ice-foot formation from december to the end of june (nielsen 1979). the bedrock geology of southeastern disko island consists of unlithified cretaceous sand stones overlaid by tertiary basalt (henderson et al. 1976). and the landscape is characterised by tertiary plateaus that have been heavily dissected by glaciers during the quaternary. the tertiary plateaus are situated around 1ooom a.s.l., and today plateau surfaces are almost completely cov ered by ice caps. in the lowermost part of the terrain, i n the unlithified sandstones, gullies have blurred the glacial origin of the landscape. the border between cretaceous sandstones and ter tiary basalts is situated ca. 400 m a.s.1. at tuapaat. during the wisconsinan/weichselian glacia tion, only a small part of disko island was covered by inland ice (frich & ingolfsson 1990; ingolfsson et al. 1990). the margin of inland ice probably lay a few kilometres north of the present shoreline on southern disko island, and an extensive ice shelf possibly occurred west of disko island (bennike 1994). the wisconsinan/weichselian extent of the local glaciers on the island is almost unknown. it is, however, known that large valley glaciers occurred in the fiords on the western coast of the island (donner 1978; ingolfsson et al. 1990). the occurrence of glaciers in the fiords on western disko island and the altitude of the holocene marine limit o n the island (60-90 m a.s.1.) suggest extensive local glaciation. during the retreat of the inland ice ca. 10 ka bp, the rsl rose to the holocene marine limit. generally, the holocene marine limit on disko island increases towards the southeast from ca. 6 0 m a.s.1. o n northwestern disko island to ca. 90 rn a.s.1. on southeastern disko island (ingolfsson et al. 1990). at tuapaat, t h e hol ocene marine limit is situated at 80 m a.s.1. between 10 ka bp and 3 ka bp, the rsl fell continuously from the holocene marine limit to coastal morpho-stratigraphy and holocene relative sea level changes 279 the present sea level (donner & jungner 1975; frich & ing6lfsson 1990; ingolfsson et al. 1990; bennike et al. 1994). during this period coarse clastic beach ridge plains developed along the shores of disko island (rasch & nielsen 1994). during the last >4 ka, the rsl in disko bugt has been very close to or below the present sea level (donner & jungner 1975; frich & ingdlfsson 1990; ing6lfsson et al. 1990). as a result, subaerial deposits containing information about marine events in this period are sparse and confined to the terrain immediately above sea level. the scarcity of information concerning marine events, including rsl changes. during the last 3-4 ka is illustrated by the very low number of radiocarbon dates on marine fossils from this period (fig. 2). study area geomorphology the research site for the field investigation is a small cuspate foreland near the mouth of the tuapaat river on the southern coast of disko island about 40 kilometres east of the town qeqertarsuaq/godhavn (fig. 1). the interior of the foreland is mainly built up of simple beach ridges (swash ridges) consisting of rounded to well-rounded pebbles and cobbles (tuapaat means well-rounded stones in inuit-language). the pattern of the beach ridges indicate that they have been formed during littoral drift from the west (figs. 3 , 4 and 5 ) . the mean elevation of the foreland is about 3 m a.s.1. a washover ridge (transgressive barrier) separates the interior of the foreland from the sea. the washover ridge is significantly higher and wider than the simple beach ridges in the interior part of the foreland (fig. 6). towards the west, the interior simple beach ridges of the cuspate foreland are superimposed by an alluvial fan (figs. 5 and 7). landward, the foreland is bounded by a fossil coastal cliff which leads to marine terraces at higher elevations. the front of the cliff is dissected by two larger and several smaller gullies. these gullies have pro duced the yellow sandy sediment for the alluvial fan that covers the coastal landscape in the west ern part of the foreland. the landscape immediately above the cuspate foreland consists of gently sloping and vegetated marine terraces with scattered exposures of coarse clastic beach sediment. the landscape has been extensively adjusted by solifluction, and it is therefore difficult to discern the detailed geo morphology of individual beach ridges even in the exposures in the vegetation. the marine terraces continue to the holocene marine limit at 80 m a.s.1. methods an age-altitude diagram based on 33 holocene dates o n terrestrial and marine material from the southeastern part of disko island and the islands of kitsissut (south of disko island) has been constructed (fig. 7). the holocene marine limit is consistently situated ca. 80-90 m a.s.1. in the area represented by the diagram (funder 1989; *i 15 1 0 1 2 3 4 5 6 9 10 1 1 time (ka bpi fig. 2. frequency distrlbution of radiocarbon dated shells and whale bones from disko bugt. the total number of i4c dates is 87. only four dates exist from the period after 4 ka bp sources for dates: weidick (1968, 1972a. 1972b, 1973,1974), donner & jungner (1975), donner (1978). bojsen & frederiksen (1980), ing6lfsson et al. (1990), frich & ingolfsson (1990), bennike et al. (1994), and the present work. 280 m . rasch & n . nielsen i ingcilfsson ct :ti. iuyo). the shaded area in the diagram r e p r e w i t 9 the band i n which the rsl cur\'e must lie (higher than dated marine material and i m w r than dated terrestrial/lacustnne material). the diagram differs from previously published emergence curves from disko bugt ( d o n n e r 6: jungner 1075: frich & ingolfsson 1990: ingolfsson et al. ly90) by only including dates from a restricted area with a uniform alti tude o f the holocrnc marine limit. i n addition. no interpretations concerning depth range of occurrence o f dated fossils a.ere applied in the ~ tuapaat, d i s k 0 island geomorphology beach ridge (recent) beach ridge (fossil) marine terrace cliff ic] lake i lagoon , alluvial fan 200 rn i fig. 3. aerial photo of the studv area at 1 uapaat (aerial photoxxk-123. copyright: kort or matrikelstyrelsen, denmark) construction of the diagram. most of the animals normally found as fossils in marine deposits in west greenland live in a wide zone (from the shoreline to water depths of tens of metres), and interpretations concerning depth range of occur rence will therefore be very uncertain unless good information about stratigraphy and sedimen tologv of t h e adjoining sediments is available ( d o n n e r & jungner 1975; andrews 1986: sutherland 1987; pirazolli 1991). a geomorphological sketch m a p of the coastal landscape at tuapaat (fig. 4) was prepared using f i g . 4 . gcomorphological sketch map of the \tudy area at tuapaat. coastal morpho-stratigraphy and holocene relative sea level changes 281 fig. 5 . the study area at tuapaat. the intenor of the cuspate foreland consists of coarse clastic simple beach ridges. in the background, towards the west, an alluvial fan covers the simple beach ridges (fig. 6). the cliff on the right aide of the photo is approximately 7 m high. aerial photograph interpretation and field data. levels of coastal landforms were measured in terrain profiles using electronic theodolite and echo-sounder (figs. 8 and 9). local datum was based on tidal observations on the location. absolute and relative errors on altitude measure ments are considered approximately 50.5 m and less than 2 0 . 2 m. respectively. a coastal rnorpho-stratigraphy of the cuspate foreland was interpreted from the geomorpho logical sketch map and from the terrain profiles (figs. 8 and 9). the term morpho-stratigraphy denotes a system for relative dating of landscape elements. a rnorpho-stratigraphic unit is a strati graphic unit primarily identified by the surface form it displays. the applied principles of coastal fig. 6. an alluvial fan superimposes the coastal deposits in the westernmost part of the study area. the alluvial fan is built up by sediments eroded from the marine terraces at higher elevations. i n the spring and early summer, the interior, eastern part of the foreland is flooded (notice the lake in left side of the photo). the lake is dammed by an ice core within the present beach ridge. the lake drains when the ice core melts in the early autumn. 282 m . rasch & iv. nielsen relative sea level southeast d i s k 0 and kltslssut rn a.s.1. 90 €3 70i i 1 50 4 0 legend: a peatigyttja 8 shells whale ? t l l l l l l l i l l l 0 1 2 3 4 5 6 7 8 9 1 0 1 1 ka bp fig. 7. age-altitude diagram of “c dates from southern disko island and kitsissut. the shaded area marks the zone in wluch the rsl curve must lie. upward directed arrows point to the threshold altitude of lakes in which dated gyttja samples have heen collected. the downward directed arrow in the lower left corner of the diagram points to the expected rsl (om a.s.1.) at the time when the whalebone in profile 2 (k-6181) was deposited. the dotted vertical line represents dating 1-6239 (see table 2 ) . the exact field altitude of this sample is unknown. i t is however known that the sample was collected above sea level. sources for the dates: see table 2. morpho-stratigraphy have been described in detail by rasch and nielsen (1994). five different morpho-stratigraphic unit types were identified at tuapaat (table 1, figs. 8 and 9). three pits were dug within profile 1 in the alluvial fan deposits in the western part of the study area (figs. 4 and 8). the northernmost and the southernmost pits both reached the surface of the beach deposits underneath the alluvial deposits. because of permafrost, it was not poss ible t o excavate to the coastal basement in the middle pit. in the northernmost pit, three layers of peat were discovered just above the coastal deposits. the stratigraphy of this pit was logged (fig. lo), samples of the different layers were analysed for grain size, and plant species within the peat layers was determined by bent fredskild, museum of botany, university of copenhagen. three different facies types were identified from the log. a whale bone was found embodied in the sedi ments on the landward side of the present beach in profile 2 in the eastern part of the foreland (fig. 9). the whale bone and the peat layers from the northernmost pit in profile 1 were radiocarbon dated (table 2). t h e samples k-6179, k-6180 and k-6181 were dated at the carbon-14 dating laboratory at the national museum of denmark, copenhagen, while sample aar-1422 was dated at the ams i4c laboratory at the university of aarhus, denmark. the date of k-6181 was corrected for isotopic fractionation by nor malising t o dl3c = 0.0%0 pdb. k-6179, k-6180 and aar1422 have been corrected by norrnal king to 6i3c = 2 5 . a 0 pdb. results age-altitude diagram the age-altitude diagram in fig. 7 illustrates well the emergence of southeastern disko island in the early part of the holocene. between 9 and 7 ka b p , the rsl fell continuously with a rate of about 3 cm/yr from ca. 8 0 m a.s.1. to ca. 30m a.s.1. the width of the shaded area in the lower part of the diagram illustrates that present knowl edge about the exact course of the emergence of southeastern disko island after ca. 7 ka bp is very limited. however, the lower part of the diagram indicates that the rsl reached present sea level in the period between 4 . 7 and 1.0 ka bp, and that it has probably been below present sea level for at least part of the period between 4 . 7 ka bp and the present. coastal morpho-stratigraphy and holocene relative sea level changes 283 fig. 8 . topographic profile from the western part of the cuspate foreland. the position of profile 1 is shown in fig. 4. (profile 1). the morpho-stratigraphy of the profile has been logged above profile 1b. the abbreviations used in the morpho-stratigraphic log are defined in table 1. a detailed log of the stratigraphy in the northernmost pit (p3) is given in fig. 10. profile 1 a tuapaat 1993 m a.s.1. m.s.1. -20 i i 1 0 250 500 750 1000 m profile 1b i wr i morpho-stratigraphy rbrp i cc i rbrp m a.s.1 legend : = beach deposil (recent) w beach deposil (fossil) l5j alluvial tan deposit el peat 10 5 ................... h.h.w.s. h.l.w.s. 0 m a.s.1 p2 i 0 legend = beach deposil (recent) w beach deposll (fossil) l5j alluvial tan deposit el peat ........................ h.h.w.s. ...* h.l.w.s. .. . ................. ....... *., 1 50 100 150 200 250 300 m t a b k 1. charactcristics of the five morpho-stratigraphic unit types identified within the cuspate foreland at tuapaat (compiled from rasch & nielsen 1994). morpho-stratigraphic unit type characteristics indication of code simple beach ridge washover ridge narrow sharp-crested beach ridge with internal beds generally dipping 5'-10" towards the sea. coastal progradation sbr beach ridge with rounded crest and with internal beds following the surface of the ridge. washover ridges are usually higher and wider than simple beach ridges. typical internal bed slopes are less than 5". coastal recession wr gently sloping marine terrace with several more or less parallel simple beach ridges on the top. coastal cliffs are usually more or less straight, coast parallel cliffs. coastal deposits will always occur at the foot of a coastal cliff. coastal recession cc limit between morpho-stratigraphic units of very different age. coastal recession mu regressive beach ridge plain coastal cliff coastal progradation rbrp morphologic unconformity 281 m . rasch & ,v. ,vielseti profile 2 tuapaat m o r p h o s t r a t i g r a p h y rerp i c c ,rbrp, w r j m a . s i. 20 1 0 50 t o o 150 200 m ,t~orpho-strfitigraph?' the morpho-stratigraphy of the cuspate foreland at tuapaat (figs. 8 and y) indicates four phases of shoreline movement. t h e marine terraces above ca. 10 m a.s.1. indicate coastal progradation ( r b k p ) . this was followed by coastal recession ( c c ) and resulted in the formation of the fossil coastal cliff at t h e northern edge of the foreland. phase three was another period of shoreline pro gradation ( r b r p ) which formed the simple beach ridge plain within the cuspate foreland. t h e tinal phase involved coastal recession ( w r ) and the development of the washover ridge at the shore line o f the foreland. the washover ridge at the present shoreline consists of two separated ridges (fig. 11). in profile 1, i t is not possible to distinguish between the two ridges. probably because the inner ridge ha3 been superimposed by alluvial fan deposits (fig. 8 ) . however. in profile 2 a sharp boundary occurs between the outer a n d the inner ridges of the washover ridge (figs. 9 and 11). o n the outer ridge the beach sediments a r e washed clean by wave5 and washovers, while lichens. comprised mostly of rhizocurpoti jeriitlandiciirri with typical diameters of 2 cm. grow on t o p of the sediments of the inner ridge. both the inner and outer ridges contain large volumes of sediment (fig. 11) and n a r l i sample no. 1920729-23 i 9 2 0 7 2 9 2 2 7930729-21 1130729-20 1930729-19 t930729-18 1920729-17 flcra reworked p a r k 01 cyperaceae reworked iresh water mosses reworked lresh w a l e r m o s s e s lab.nc. k-6180 k-6181 a a a 1 4 2 2 age " c y b p 390: 55 480' 75 980 2 60 fig. 10. l o g of t h e c t r a t i g r a p h y in t h e n o r t h e r n m o s t pit (p.3) i n protilc 1 (fig. 8). g r a i n s i r e ( m , ) and s o r t i n g ( d , ) arc given i n f v a l u e s . facies 1 consist, of t h i n l e n t i c u l a r l a y c r s o f band a n d d t . r o o t h o r i z o n s o c c u r s c a t t e r e d within the facies. the facies type ha\ been i n t e r p r e t e d iis alluvial f a n deposits facics :consists of;i p o o r l y w r t c d . \ l i t ? d i m c n t with r c w o r k c d parts ( i t pl,inr\ and n i o s \ e c t h e f a c w tvpc h a s h s e n i n t e r p r e t e d ;is lake s e d i m e n t \ o r i g i n a t i n g f r o m sinall p o o l \ in d c p r c 4 o n i in t h e al1uvi.d f a n . fmrs 3 c o n s i s t s of \and with \c.ittered o c c u r i c n c c \ o l roundcd-\ccll r o u n d e d pehhles a n d cobble\. 'this facics typc has been i n t e r p i e l e d n\ h e a c h d i i n c n t s coustul tiiorpho-jtrutigrupliy atid holocetie rekutiue sea leuel cliatigrs 285 tuhlr 2. radiocarbon dates from the southeastern part of disko island and kitsissut. where possible. dates on marine material have heen corrected for isotopic fractionation by normalising to 6°c = o.mr pdb. while dates on terrestrial niatcrial have heeti corrected for isotopic fractionation by normalizing to 6'3c = -25.0% pdb. ~ lac no. 3 10 10 10 5 10 7 3 6 5 6 5 5 3 6 6 1 3 2 3 3 2 2 4 9 8 11 11 9 9 6 6 1 ldh n 0 k-5774 ~ 6 1 8 0 ~ 6 1 8 1 k-6179 k-5777 hel-945 aar-1422 ua-1787 k-5775 k-3908 k-5778 k-3909 k-5779 1-6239 k-5776 k-3666 k-3691 k-3505 hel-904 hel-905 hel-903 lu-3040 hel-906 hci-907 lu-3038 k-4568 rcd-21 k-3660 k-3667 hel-7210 k-4567 aar-5 k-3665 __ n idt ~ 69"27' 69024' 6y24' 69"24' 69"16' 6929' 69"24' 6y04' 69"27' 69"17' 69"16' 69"17' 69"16' 69"16' 69"27' 69"17' 6y15' 69"32' 6927' 69"29' 69"26' 69"26' 69"29' 69"29' 69"26' 69"18' bk"59' 6t40' 69"40' 6978' 69"ix' 69"17' h9"17' __ w long. 53"40' 52"37' 52"36' w37' 53"50' 53"38' 52"31' 53"32' 53"40' 53"28' 53"50' 53%' 53"50' 53"50' 53"40' 53"28' 53"35' 53"41' 53"40' 53"38' 53"42' 53"35' 53"38' 53"38' 53"27' 53%' 53"ly' 52"00' p o l ' 53"15' 53"15' 53"28' 53"28' ~ material gyttja peat whale peat gyttja peat peat peat gyttja gyttja gyttja gyttja gyttja shells gyttja gyttja shells gyttja shells shells shells shells shells shclls shells shells shells shells gyttja shells shells shells gyttja elevation m a.s.1. 13.5' 2.9 3.1 3.2 112 0.3 3.5 5.2 12.5' 82 102 82 8.5' ?3 13' 82 5-7 20-30 18.7 3.3 6.8 45 40.3 21.6 10-12 69 62 40 100 69 28 82 82 age. "c yr5 b p 370? 55 390 2 55 480? 75 670 -t 75 890-t 65 y70 ? 110 9xut60 1610 ? 100 1780t55 2050t80 2330t75 3900+ 90 3930% 85 4685 t120 4730 % 115 53102 95 5990t95 6750 + 105 681)o t150' 6840 t140 8050 ? 170' 8170% 80 8280 + 170' 8340 % 170' 8390 2 80 8620 2 120 8690k 90 x700 ti20 8950 t125 9060 2 120' 9220 ? 130 9240 2 250 10180 t155 b ' t % pdb reterence -20.1 -27.7 -14.5 -27.7 -24.3 -28.2 -20.6 -24.2 -22.3 -24,s -24.1 -23.5 -24.7 i .o -22.8 2.1 i .5 1 .8 1.1 2 . 0 4.5 0.9 0.8 0 . 3 12.9 1.7 0.6 -23.7 1 .n bennikr 1994 this work this work this work bennike 1994 donner 1978 this work bennike et al. 1994 bennike 1994 ingolfsson et al. 1990 bennike 1994 ingdfsson et al. 1990 bennikc 1994 weidick 1973 bennike et al. 1990 ingolfsson ct al. 1990 ingnlfsson ct a l . 19yo foged 1989 donner 1978 donner 1978 donner 197x ingdtsson et al. 1990 donner 1978 donner ly7x ingolfsson et al. 1990 frich b ingolfsson 1990 bennike et al. 1994 lngdfsson et al. 1990 ing6lfsson et al. 1990 frich b lnp6lfsson 1990 frich & lngnlfsson 1 y y o ingdlfsson et al. i y y o ingolfsson et al. 1y90 ' datc was not corrected for isotopic fractionation by authors of tirst publication. date has been corrccted to b"c = 0.0% pdb. ' threshold of lake situated at 16.5 m a d . ' a field altitude of 19m a.s.1. was quoted by weidick (1973). according to frich & ingdfsson (1990) this altitude is incorrcct. have small dunes developing o n the surface. it is unlikely that the ridges a r e ephemeral coastal landforms resulting from single larger storms. t h e ridges more probably represent permanent fea tures developed at different times as a result of coastal recession. the basal peat (fig. 10, 3 . 0 6 3 . 0 8 rn a.s.1.) in the northernmost pit (p3) in profile 1 was dated t o 980 * 60 bp (aak-1422). t h e date implies that the fossil coastal cliff behind the cuspate foreland, and at least the inner part of the simple beach ridge plain of the cuspate foreland, developed before 980 5 60 bp t h e ksl did not reach the present sea level before 4.7 ka. accordingly, the fossil coastal cliff developed during the period between 4.7 and 1 ka bp t h e whale bone that was found in the inner beach ridge of the washover ridge was dated to 480 2 75 bp (k-6181). this result implies that the inner beach ridge of the washover ridge was active in the 15th century, that the simple beach ridge plain of the cuspate foreland was developed before the 15th century, and that the o u t e r beach ridge of the washover ridge was formed after the 15th century. 286 m . rasch & n. nielsen discussion there has been some confusion about the shape of holocene rsl curves of disko bugt. donner and jungner (1975) used a best fitting second degree polynomia for their construction of a rsl curve representing the entire disko bugt. the curve shows emergence in the period between deglaciation and about 1.5 ka bp followed by sub mergence in the period between 1.5 ka bp and the present. according to their curve, the rsl was below present sea level between ca. 3 ka bp and the present. in later attempts to construct rsl curves for the entire disko bugt. it has been presumed that the rsl fell continuously with a decreasing rate throughout the holocene, and that the rsl did not fall below present sea level (frich & ingolfsson 1990: ingolfsson et al. 1990). the present study supports donner and jungner’s idea of a rsl history characterised by emergence in the early part of the holocene followed by submergence in the late holocene. in the nuuk area in the southern part of west greenland, norse ruins that now occur below sea level demonstrate that the rsl in that area has been lower than at present (weidick 1976). no such unequivocal indication of lower than present relative sea level has been observed on south eastern disko island. however, in disko bugt, frequent occurrence of eskimo ruins that have been partly destroyed by coastal erosion con fig. j l . the washover ridge that encompasses the cuspate foreland at tuapaat consists of two separated ridges. the inner ridge is covered by the lichen, rhizocarpon jemflarrdicum, with typical diameters of 2 cm. n o lichens occur on the outer ridge. notice the small dunes on top of the ridges. vincingly suggest that one or more transgressions have occurred since habitation of the ruins (mathiassen 1934). the theory is strongly sup ported by the fact that washover ridges and coastal cliffs occur frequently along the present shores of southern disko island (rasch & nielsen 1994). in addition, a dorset-culture ( 6 0 0 4 bc) midden that was found below the mean high water level in the southeastern part of disko bugt is difficult to explain without presuming that the rsl has been below present sea level ( j . f. jensen, museum of qasigiannguit pers. comm.). the proposed late holocene submergence in disko bugt may have resulted from isostatic adjustment to late holocene (neoglacial) glacier advances (kelly 1980; funder 1989). alterna tively, the proposed holocene rsl changes on southeastern disko island (emergence in the early part of the holocene followed by late holocene submergence) might have resulted from the migration of a collapsing fore-bulge. rsl-curves showing emergence followed by submergence occur frequently in the literature concerning rsl changes in the outer part of formerly glaciated areas (e.g. forman 1990; quinlan & beaumont 19-31), and convincing accordance between such rsl-curves and theoretical rsl-curves has been achieved in geophysical models that include the migration of a collapsing forebulge o n a visco elastic earth (clark et al. 1978; quinlan & coastal morpho-stratigraphy and holocene relative sea level changes 287 beaumont 1981; andrews & peltier 1989; liverman 1994). only trends of the rsl history can be inter pre'ted from age-altitude diagrams. the inves tigation of the morpho-stratigraphy in the lowermost part of the coastal landscape at tua paat does, however, allow a discussion of possible smaller fluctuations of the rsl in the latest part of the holocene. changes in the shoreline position (recession/progradation) at a given location must result from either changes of the rsl, shifting of the wave climate or changes of littoral sediment sources. changes in shoreline position caused by shifting wave climate or changes of the littoral sediment sources will be expected to have only local significance, while changes in shoreline posi tions caused by rsl changes will be expected to have significance over larger areas and to occur on coasts with different exposure and sediment sources. therefore, when indications of synchron ous and similarly directed shoreline movements are observed at locations with different exposure and sediment sources, it is most probable that the shoreline movements have resulted from chang ing rsl. coastal landscapes with a morpho-stratigraphy very similar to the morpho-stratigraphy of the cuspate foreland at tuapaat are common on disko island (fig. 12). therefore, it is suggested that the morpho-stratigraphy at tuapaat, and at the other disko island study sites, reflects shore line displacements caused by rsl changes. this suggestion implies that the proposed coastal recessions at tuapaat in the period between 4.7 and 1.0 ka bp, before and after the 15th century, all resulted from transgressions caused by rising rsl. unfortunately, the tuapaat field obser vations do not allow for an exact determination of the relative sea level at the transgression maxima. weidick (1993) has suggested that transgression maxima occurred in the coastal part of west greenland in the 14-15th century and in the middle of the present century. this interpretation is based on archaeological observations of the fig. 12. topographic profiles of the lowermost part of the coastal landscape at different sites on disko island (compiled from rasch et al. in press). all profiles have been measured perpendicular to the shoreline. the morpho-stratigraphy of the profiles has been logged above the profiles. the abbreviations used in the morpho-stratigraphic log have been defined in table 1 . m 3,s i. saoqarliit ilorllll n 60'44'n 54'32'w m.s.1. tuapaat 68'24" 52'35'w 0 50 iw m 0 50 1w 150 m 288 m . rasch & n . nielsen spatial relation between the present shoreline and thule-culture eskimo ruins of different ages (mathiassen in gabel-j~rgensen & egedal 1940) and on early tidal observations (saxov 19.58). recently, supporting evidence for this theory have been found i n a study of morpho-stra tigraphy and chemical stratigraphy within a coastaflagoonal landscape system at saqqarliit ilorliit on western disko island (unpubl. data) (fig. 1). at saqqarliit ilorliit, high sodium and sulphur content and relatively coarse grain sizes in lagoon sediments from the 14th century and the middle of the present century might suggest transgression maxima in these periods. based on the saqqarliit ilorliit data it might further be suggested that transgressions have occurred early in the period between 2.5 and 0.7 ka b p and i n the 1 6 1 7 t h century. the morpho-stratigraphy at saqqarliit ilorliit is illustrated in fig. 12. the transgression early in the period between 2.5 and 0.7 ka bp led to the formation of the coastal cliff, while the transgressions in the present millennia led to the development of the washover ridge immediately landward of the shoreline and to marine influenced sedimentation in lagoons behind the washover ridge. considering the errors on radiocarbon dates, t h e tuapaat results agrees well with the pre liminary results from saqqarliit ilorliit. the coastal cliff at tuapaat may have formed during the transgression that was dated to the period between 2.5 and 0.7 k a bp at saqqarliit ilorliit. the date of 980 2 60 bp on the peat sample from the northernmost pit (p3) in front of the fossil coastal cliff at tuapaat only implies that the cliff was formed before ca. 1.0 ka bp consequently, the dating reduces the possible time interval for the transgression to the period between 2.5 and 1.0 ka bp. the inner beach ridge of the washover ridge at tuapaat was probably active during the 14-15th century transgression maximum, and the outer beach ridge of the washover ridge might have formed during the 1 6 1 7 t h century transgression and/or during the transgression culminating in the present century. an age of at least 500 years on the washover ridges constituting the present beaches in disko bugt also agree well with the implications of a date of 380 2 80 bp (1-16414) on a whale bone that was found in the present beach ridge on the western part of nuussuaq peninsula, northwestern disko bugt (bennike et al. 1994; 0. bennike; geological survey of denmark pers. comm.). this whalebone was probably also deposited during or after the transgression cul minating in the 14-15th century. a morpho-stratigraphic sequence similar to that at tuapaat has also been described from siniffik ca. 20km west of tuapaat (fig. 12) (rasch & nielsen 1994). based on the sizes of lichens, rhizocarpon jemtlandicum, on the beach ridges at siniffik and on the oldest buildings in the town of qeqertarsuaq, it was suggested that the relict coastal cliff (fig. 12, cc) at siniffik developed during a transgression in the middle of the 15th century. as the morpho-stratigraphic sequences at siniffik and tuapaat are almost identical, it is probable that the individual mor pho-stratigraphic units at the two sites developed synchronously. this implies that the fossil coastal cliff at siniffik was formed before 0.7 ka bp. conclusions between 9 and 7 ka bp the rsl on southern disko island fell continuously with a rate of about 3 cm/ y r from ca. 8 0 m a.s.1. (the holocene marine limit) to ca. 30 m a.s.1. the rsl reached present sea level between 4.7 and 1 .o ka bp present knowl edge of the course of the rsl curve on southern disko island between 7 and 1 ka bp is very limited due to the scarcity of dates on marine material from this period. it is suggested, however, that the rsl history of southern disko island was one of emergence in the early part of the holocene followed by submergence in the late holocene. the suggestion implies that the rsl has been below present sea level during the period between 4.7 ka bp and the present. indications of at least three late holocene trans gressions were found at tuapaat. the exact timing of the transgressions is unknown, though several data suggest that the first transgression occurred early in the period between 2.5 and 1.0 ka bp, that the second transgression culminated in the 14-15th century, and that the third transgression culminated in the middle of the 20th century. in addition, one transgression may have occurred in the 16-17th century. acknowledgements. the field investigations at tuapaat were funded by the danish natural research council and were carried out during the summers of 1993 and 1994. logistics for the field work and transportation to the field site were provided by the arctic station in godhavn/qeqertarsuaq. thanks are extended to b. fredskild for determination of plant species coastal morpho-stratigraphy and holocene relative sea level changes 289 in peat samples, to 0. humlum and j . desloges for helpful comments on the manuscript, t o p. unger, k. kjaer, t . olsen and p. olsen for assistance in the field and to j . jdnsson and 0. b. berthelsen for technical help with the figures. references andrews. j . t . 1986: elevation and age relationship: raised marine landforms in glaciated areas: examples based on canadian arctic data. pp. 67-95 in van de plassche, 0. (ed.): sea leuel research: a manual for the collection and eualuation of data. geobooks, nonvich. andrews, j . t . & peltier, w. r. 1989: quaternarygeodynamics in canada. pp. 541-572 in fulton, r . i . (ed.): quaternary geology of canada and greenland. geological survey of canada, geology of canada 1. bennike, o . , hansen, k. b . , knudsen. k. l., penney. d . n. & rasmussen, k . l. 1994: quaternary marine stratigraphy and geochronology in central west greenland. boreas 23. 194-215. bojsen, t . & frederiksen, l. 1980: kystmorfologi ved ivisarqut og narssarssuk. pp. 31-64 in engraf, a , , nielsen, j., nielsen, n. & humlum, 0. (eds.): arktisk geomorfofologi, enoks haon. dbko 1978. kobenhavns universitets geografiske institut, geonoter 5. carter, r . w. g. & orford. j . 1984: coarse clastic barrier beaches: a discussion of the distinctive dynamic and morpho sedimentary characteristics. mar. geol. 60, 377-389. clark, j . a , , farrel. w. e. & peltier, w. r . 1978: global changes in postglacial sea level: a numerical calculation. q. res. 9 , 265-287. donner, j . & jungner, h . 1975: radiocarbon dating of shells from marine holocene deposits in the disko bugt area, west greenland. boreas 4 , 25-45. donner. j . 1978: holocene history of the west coast of disko, central west greenland. geogr. ann. 60a, 63-72. forman. s . l. 1990: post-glacial sea level history of north western spitsbergen, svalbard. geol. soc. a m . bull. 102. 1580-1590. frich, p. & ingolfsson, 0. 1990: det holoczne sedimen tationsmiljd ved igpik samt en model for den relative land h a n i n g i disko bugt omridet, vestgronland. dan. geol. foren. h s k r . 1987-89, 1-10, funder, s . 1989: quaternary geology of the ice-free areas and the adjacent shelves of greenland. pp. 743-792 in fulton, r. j. (ed.): quaternary geology of canada and greenland. geological survey of canada, geology of canada 1. gabel-jergensen, c. c. a . & egedal, j . 1940: tidal obser vations made at nanortalik and juliannehaab in 1932-1934. medd. gr(n1. 107(2). 47 pp. henderson, g., rosenkrantz, a. & schiener, e. j . 1976: cretaceous-tertiary sedimentary rocks of west greenland. pp. 341-362 in escher, a . & watt, a . s . (eds.): geology of greenland. gronlands geologiske undersogelse, k ~ b e n h a v n . glacier initiation line altitude: a methodological approach to the study of rock glaciers. arc. alp. res. 20(2), 160-178. ing6lfsson, 0.. frich, p., funder, s . & humlum, 0. 1990: paleoclimatic implications of an early holocene glacier advance on disko island, west greenland. boreas 19. 297-311. kelly, m. 1980: the status of the neoglacial in western greenland. grgnl. geol. unders. rapp. 96. 14 pp. kelly, m . 1985: a review of the quaternary geology of western greenland. pp. 461-501 in: andrews, j . t . (ed.): quaternor?. enoironments, eastern canadian arctic, bafjirt bay and western greenland. allen and unwm, boston. liverman. d. 1994: relative sea level history and isostatic rebound in newfoundland, canada. boreas 23. 217-230. mathiassen, th. 1934: contribution to the archaeology of disko bay. medd. grgnl. 93(2). 192 pp. nielsen, n. 1y79: ice-foot processes. observations of erosion of a rocky coast, disko, west greenland. zeitsch. geomorph. pirazzoli, p. a . 1991: world atlas of holocenesea level changes. elsevier. amsterdam. 300 pp. quinlan. g. & beaumont, c. 1981: a comparison of observed and theoretical postglacial relative sea level in atlantic canada. can. j . earth sci. 18, 11461163. rasch, m. & nielsen, n. 1994: holocene relative sea level changes indicated by morpho-stratigraphic sequences: disko island. west greenland. geogr. tidrskr. 94, 37-45. rasch, m . , christiansen, h . h., hansen, b. u., hasholt. b., humlum, 0.. jakobsen, b. h . & nielsen, n. in press: greenland landscape elements as indicators of rapid environ mental change. in berger, a. r. (ed.): internationa[ work shop of geological indicators of rapid environmental change. corner book, new foundland. july 11-17, 1994. a. a . balkema publishers, rotterdam, netherlands. saxov, s . 1958: the uplift of western greenland. medd. dan. geol. foren. 13, 51&523. sutherland, d. g . 1987: dating and associated methodological problems in the study of quaternary sea level changes. pp. 16s197 in devoy, r . j . n. (ed.): sea surfacestudies: a global oiew. croom helm, london. tanner, w. f. 1988: beach ridge data and sea level history from the americans. j . coast. res. 4 , 81-91. weidick, a. 1968: observations on some holocene glacier fluctuations in west greenland. medd. grdnl. 165(6). 202 pp. weidick, a. 1972a: c" dating of survey material performed in 1971. grdnl. geol. unders. rapp. 45, 5 6 6 7 . weidick. a . 1972b: holocene shore-lines and glacial stages in greenland an attempt to correlation. grgnl. geol. unders. rapp. 41. 39 pp. weidick, a . 1973: c l 4 dating of survey material performed in 1972. grdnl. geol. unders. rapp. 55, 6 6 7 5 . weidick, a . 1974: ci4 dating of survey material performed in 1973. grdnl. geol. unders. rapp. 66, 42-45. weidick. a. 1976: glaciation and the quaternary. pp. 431-458 in escher, a . & watt, a . s. (eds.): geology of greenland. gronllands geologiske undersogelse, kobenhavn. weidick, a . 1993: neoglacial change of ice cover and the related response of the earth's crust in west greenland. gronl. n.f. 23(3), 321-331. humlum, 0. 1988: rock glacier appearance level and rock geol. unders. rapp. 159, 121-126. por_003.fm 48 polar research 26 (2007) 48 – 63 © 2007 the author abstract this paper presents a survey of the mollusc fauna in kongsfjorden, an arctic glacial fjord in spitsbergen, svalbard, based on 197 samples collected with van veen grabs, dredges, scuba-diving collections and baited traps at depths ranging from 5 to 390 m. eighty-seven mollusc species were recorded. the species distribution accords well with the distribution of the main substrata: barren rock, kelp bed, gravel and soft bottom. for the most common substrate type, the soft bottom, the distribution and diversity of molluscs were analysed in relation to environmental factors. glacial activity (particularly the inflow of glacial meltwater loaded with mineral solids) is responsible for the main gradients of environmental variables in the fjord. silt concentration in sediments, the water temperature near the bottom and inorganic suspensions in the surface water best predict the species distribution of the soft bottom. two faunal associations located in glacial bays and three faunal associations in the central basin of the fjord can be distinguished for the fauna of the soft bottom. molluscs are much more abundant in glacial bays (200–300 individuals (ind.) 0.1 m 2 ) than in the central basin assemblages (30–40 ind./0.1 m 2 ). yoldiid ( yoldiella solidula , y. lenticula and yoldia hyperborea ) and thyasirid bivalves ( thyasira dunbari , t. gouldi and axinopsida orbiculata ) cope particularly well with glacial sedimentation and occur in high quantities in glacial bays. although there is no effect of glacial disturbance on the molluscan sample species richness and species diversity, there are significant clines of evenness and taxonomic distinctness in areas near to the glacier. the patterns of molluscan diversity are not fully consistent with the patterns described for complete macrobenthic communities. kowalczuk molluscs in kongsfjorden (spitsbergen, svalbard): a species list and patterns of distribution and diversity maria w odarska-kowalczuk institute of oceanology, polish academy of sciences, sopot, poland l keywords mollusca; glacial fjord; species list; species distribution; diversity; svalbard. kongsfjorden is situated on the west coast of spitsbergen, which is the largest island of the svalbard archipelago. despite its high latitude location (79 ° n) the fjord has a sub-arctic character (hop et al. 2002). the outer and central basins of kongsfjorden are influenced by the warm atlantic waters of the west spitsbergen current (svendsen et al. 2002). three tidal glaciers terminate in the fjord. kongsbreen, situated in the innermost part of the fjord, is the most active glacier in the svalbard archipelago (lefauconnier et al. 1994). there is an international research centre in the settlement of ny-ålesund, which makes kongsfjorden one of the most intensively studied high latitude fjords. the physical and biological settings of the fjord have been reviewed by svendsen et al. (2002) and hop et al. (2002). the implementation and networking of large-scale long-term marine biodiversity in europe (biomare) project selected kongsfjorden as one of the european marine biodiversity research sites, which provide reference localities for large-scale european biodiversity studies (warwick et al. 2003). the biota inventory in selected sites is a crucial starting point for large-scale studies of temporal and spatial changes of coastal biodiversity (stork et al. 1996). species richness records are largely dependent on the sampling effort (magurran 2004). the assessment of species richness of a marine bay, an inlet or an island requires intensive sampling using a variety of sampling techniques, and preferably covering several sampling seasons (bouchet et al. 2002). correspondence m. w odarska-kowalczuk, institute of oceanology, pas, powstancow warszawy 55, 81-712 sopot, poland. email: maria@iopan.gda.pl doi:10.1111/j.1751-8369.2007.00003.x l m. wl odarska-kowalczuk molluscs in kongsfjorden (spitsbergen, svalbard) polar research 26 (2007) 48 – 63 © 2007 the author 49 molluscs are widely distributed and can be abundant in a variety of marine habitats ranging from rocky shores to abyssal muddy plains. molluscs can be highly responsive to local human activities (terlizzi et al. 2005) as well as to either long-term or large-scale climatic changes (mieszkowska et al. 2006), and have been proposed as possible surrogates for the study of the distribution and diversity of the whole macrobenthic community (anderson et al. 2005; smith 2005). in arctic fjords molluscs exhibit the highest preservation potential among the marine macrobenthic biota (aitken 1990). between 30 and 60% of the modern arctic mollusc fauna is represented in quaternary marine arctic macrofossils, and understanding the environmental factors controlling the distribution of living communities is crucial for reconstructing the palaeoecology of quaternary glaciations and interglaciations (gordillo & aitken 2000). the macrobenthic communities of kongsfjorden have been described in several publications. kendall et al. (2003), wl odarska-kowalczuk & pearson (2004), wl odarska-kowalczuk et al. (2005) and somerfield et al. (2006) studied the distribution and diversity of subtidal communities of the soft bottom at depths ranging from 30 to 300 m. the shallow subtidal macrofauna has been described by kaczmarek et al. (2005) and bick & arlt (2005). lippert et al. (2001) studied the phytophylous macrofauna at a single location close to the island of blomstrandhalvøya. jorgensen & gulliksen (2001) investigated the fauna of the hard bottom at the kvadehuken at a depth of 20–30 m using a suction sampler and underwater photography. rozycki (1991) published a list of molluscs found at 12 stations sampled with grabs and dredges. those studies were limited in scope to a single location, habitat or depth range within the fjord. the published information on mollusc diversity and distribution in kongsfjorden is scattered and incomplete. in the present study i bring together extensive distributional data of molluscs collected in several benthic surveys carried out in kongsfjorden by the institute of oceanology, polish academy of sciences, in 1996–2000. the material contains 197 samples taken with a variety of sampling gear at a range of depths and habitats, and is likely to give a reliable assessment of the mollusc diversity and distribution patterns in the fjord. the aims of the paper are to (1) present a mollusc species list for kongsfjorden; (2) identify the environmental predictors of the mollusc species distribution; (3) identify the species characteristic for fjord habitats/mollusc associations; (4) quantify the response of molluscs at the soft bottom to glacial disturbance and compare it with the perturbation signal in the whole macrobenthic community (as described by wl odarska-kowalczuk et al. 2005). study area kongsfjorden is an open fjord located on the north-west coast of spitsbergen in the svalbard archipelago (12 ° e, 79 ° n; fig. 1). the fjord is 26 km long, with an area of 231 km 2 . depths rarely exceed 400 m. two tidal glaciers (kongsbreen and conwaybreen) terminate in the inner basin, whereas a third one, blomstrandbreen, is situated on the northern mid-fjord coast. the hydrology of kongsfjorden is shaped by the interplay among: (1) warm saline atlantic waters entering the fjord from the shelf [temperature ( t ) > 1 ° c, salinity ( s ) > 34.7]; (2) local fjord waters ( t < 1 ° c, salinity s > 34.4); (3) freshwater input from the glaciers (svendsen et al. 2002). in the inner basin there are deep depressions in which very cold winter waters ( t < − 0.5 ° c, s > 34.4), which are the remnants of winter cooling and deep convection, can be also observed (svendsen et al. 2002). fairly uniform fine sediments cover much of the kongsfjorden subtidal region, particularly in the inner basin where high sediment deposition rates are accompanied by relatively weak currents (wl odarskakowalczuk & pearson 2004). gravel beds occur in some parts of the outer fjord where strong bottom currents winnow out fine sediments. ice rafted pebbles and stones (drop-stones), typical of arctic glaciated fjords (dale et al. 1989), are distributed all over the fjord. at the edge of the fjord there are rocky shelves (jorgensen & gulliksen 2001) that gradually change into mixed bottom (hard bottom with macroalgae and bedrock with pockets of soft sediment) in the shallow subtidal region in the middle of the fjord (kaczmarek et al. 2005). kelp forests ( alaria esculenta, laminaria saccharina and l. digitata ) are restricted to sites sheltered from drifting icebergs and with limited grazing by sea urchins (lippert et al. 2001; hop et al. 2002). the meltwater inflows from the kongsfjorden glaciers result in a steep gradient in both the concentration of mineral suspensions and the sedimentation rates in the water column (svendsen et al. 2002). the sediment accumulation rate decreases by about one order of magnitude from the kongsbreen glacial bay (20 000 g m − 2 a − 1 ) to the central part of the fjord (1800–3800 g m − 2 a − 1 ) and, again, by another order of magnitude towards the outer fjord (200 g m − 2 a − 1 ; svendsen et al. 2002). intensive sedimentation results in the formation of unconsolidated labile sediments (syvitski et al. 1987). near-glacier sediments may be scoured by icebergs (of up to 10 m in height) that either circulate or stay anchored in the inner basin (dowdeswell & forsberg 1992). the organic matter supply to benthic biota decreases towards the inner basin, where primary productivity is 50 polar research 26 (2007) 48 – 63 © 2007 the author molluscs in kongsfjorden (spitsbergen, svalbard) m. wl odarska-kowalczuk limited by high levels of water turbidity and where the available organic matter is diluted by the huge mineral sedimentation (gorlich et al. 1987). the outer fjord and shelf waters are influenced by atlantic waters and have an enhanced marine organic matter supply (winkelman & knies 2005). the particulate organic carbon (poc) concentration in kongsfjorden sediments increases along the fjord axis from 0.1–0.2 mg g − 1 in the kongsbreen glacial bay and 0.3–0.5 mg g − 1 in blomstrandbreen glacial bay to 1.1–2.4 mg g − 1 in the outer fjord and shelf sediments (fetzer et al. 2002; wl odarska-kowalczuk & pearson 2004). materials and methods material was collected during cruises with the rv oceania and land expeditions based at the norwegian polar institute station in ny-ålesund during the summer seasons from 1996 to 2000. samples were collected throughout the fjord (fig. 1) using a range of techniques (table 1). eighty quantitative samples were taken using van veen grabs, 117 samples were collected using qualitative methods (dredges, scuba-diving and baited traps). three replicate samples were collected at van veen grab and scuba-diving stations (with the exception of a few van veen grab stations where only one replicate was taken because of navigational difficulties). one replicate was taken at each station sampled using either an epibenthic sledge or baited traps. either five or six samples from sites situated along the depth transect (5, 10, 15, 20, 30 and 50 m) were taken at six stations using a small rectangular dredge. the small dredge, epibenthic sledge and baited traps were constructed with 1 mm mesh size nets. samples were sieved on either 0.5 mm mesh (van veen grabs and samples collected by a diver) or 1 mm mesh (all samples from dredges and baited traps). all animals were sorted, identified to the lowest possible taxonomic level and counted. some individuals could not be identified to species level as either the shells were damaged or the organisms were juvenile and specific traits were not fully developed. the species names and taxonomic affiliations are consistent with the european register of marine species (available at www.marbef.org/data/erms.php). the number of observed species ( s obs ) was plotted as a function of the sampling effort. a species accumulation curve with 95% confidence intervals was computed using the formulae of colwell et al. (2004). two alternative approaches can be applied to estimate true species richness: the extrapolation of the accumulation curve (to predict an asymptote); non-parametric techniques based on the concept that rare and uncommon species carry information about the number of species missing in samples. the michaelis-menten ( mm ) function was used to generate an asymptotic curve that fitted the species accumulation curve (magurran 2004). chao2 , a non-parametric estimator based on species occurrence data ( chao2 = s obs + q 1 2 /2 q 2 , where q 1 is the number of species that occur in just one sample and q 2 is the number of species that occur in exactly two samples) was also calculated (chao 2004). the mm asymptote estimation and chao2 , along with log-linear 95% figure 1 location of sampling stations. kvadehuken kapp guissez blom strandbreen conwaybreen k o n g s b r e e n blomstrandhalvøya greenland svalbard norway kongsfjorden 0o 70on 80on van veen grabs (38-380 m) scuba diving (10 m) epibenthic sledges (30-390 m) baited traps (5-60 m) transects shallow water dredging (5-50 m) glacier front nyålesund m. wl odarska-kowalczuk molluscs in kongsfjorden (spitsbergen, svalbard) polar research 26 (2007) 48 – 63 © 2007 the author 51 confidence intervals as suggested by chao (1987), were computed using e stimate s (colwell 2005). constrained ordination techniques were used to explore the relationship between mollusc species distribution and environmental settings (ter braak & smilauer 2002). the data collected using quantitative (van veen grabs) and qualitative (dredges and scuba-diving) methods were treated separately. the material obtained with baited traps differed much from other samples and was not considered in the analyses. only presence/absence data were used for qualitative material. the quantitative data (van veen grabs) were square-root transformed prior to analyses. the set of environmental variables used in the analyses of qualitative mollusc samples included depth, longitude (as a proxy for distance to the glacier) and six nominal variables, namely, presence of rock, mud, sand, gravel, kelp and drop stones. the analyses of the grab data were performed only with data from a 1998 benthic cruise. the following environmental variables were recorded: depth, longitude (as a proxy for distance to the glacier), temperature and salinity of the water near the bottom, concentration of mineral and organic suspensions in surface waters, occurrence of drop stones, percentage of gravel, sand, silt and clay, mean grain size and the concentration of poc and the poc : particulate organic nitrogen concentration in sediment (pon) ratio in sediments. the results of a preliminary de-trended correspondence analysis (dca) pointed to canonical correspondence analyses (cca) as the most appropriate for the qualitative data, and to redundancy analyses (rda) as the best suited for the grab data (ter braak & smilauer 2002). the forward selection of environmental variables was used to identify and rank their importance of variables in determining the species distribution (ter braak & smilauer 2002). the forward selection method performs the following functions:it estimates the fit of each variable separately (marginal effects); it selects the best variable; and it ranks all the remaining variables on the basis of the fit that each variable gives in conjunction with the selected variable(s) (conditional effects). in the case of grab data, a subset of best fitted variables was selected. the selection of best fitted variables was performed via repeated forward selection analyses and the progressive elimination of variables with non-significant conditional effects until a set of variables with only significant effects was attained. the significance of the ordination axis in cca and in rda, and the effects of environmental variables, were tested employing monte carlo permutation tests using 499 unrestricted permutations. the analyses were carried out using c anoco v. 4.5 software (ter braak & smilauer 2002). clustering (using group-average linking) of braycurtis similarities was used to visualize the patterns of mollusc distribution. again presence/absence qualitative data and square root transformed quantitative data were used. based on the resulting dendrograms, groups of samples of similar composition (mollusc associations) were distinguished. the frequency, dominance, average abundance and indices of the community fidelity (salzwedel et al. 1985) of each species were calculated for mollusc associations defined by multivariate analyses. the indices of fidelity included das (degree of association regarding stations, i.e. the number of stations within the association at which the species concerned occurred as the percentage of the total number of stations at which this species occurred) and dai (degree of association regarding individuals, i.e. the number of individuals of the species concerned within the group as a percentage of the number of individuals of that species found in the whole study area) (salzwedel et al. 1985). the following criteria have been used to select the species that are the best descriptors of the associations on the soft bottom: typical species (frequency > 75%, dominance > 2%) and characteristic species (typical + either dai or das > 60%). in the case of qualitative data only frequency and das was considered, and species of frequency > 25% and das > 60% were regarded as characteristic species. table 1 sampling effort and basic information on samples used in the kongsfjorden mollusc study. the table includes references to papers with details of sampling methods and the locations of stations. sampling year sampling gear number of stations number of samples depths (m) reference 1997 van veen grab, catching area of 0.1 m 2 14 33 38–380 wl odarska-kowalczuk & pearson 2004 1998 16 47 40–355 1996 epibenthic sledge 9 9 30–300 — 1997 8 8 35–390 1999 12 12 35–300 2000 5 5 140–330 1999 small rectangular dredge (80 × 30 cm) 6 32 5–50 kaczmarek et al. 2005 2001 collection by diver, frame 0.25 m 2 9 27 10 kuklinski & porter 2004 1998–2000 baited traps 24 24 5–60 legezynska 2001, 2002 52 polar research 26 (2007) 48 – 63 © 2007 the author molluscs in kongsfjorden (spitsbergen, svalbard) m. wl odarska-kowalczuk the differences in n (number of individuals per sample) between associations distinguished based on grab samples were tested using the non-parametric kruskal-wallis test, as even after transformation variances could not be homogenized. post-hoc testing of differences between pairs of associations was performed using pair-wise mann-whitney u tests. species richness defined as the total number of species in a sample ( sp ), species diversity measured using the shannon-wiener index ( h ) and the evenness (equitability) of distribution of individuals between species as estimated by the pielou index ( j ) were calculated for quantitative samples. the differences in sp , h and j between the associations were tested using a oneway anova . the fisher’s lsd (least significant difference) tests were used for post-hoc multiple comparisons. to explore the taxonomic diversity of samples, two measures of taxonomic distinctness were calculated: avtd (average taxonomic distinctness of presence/absence data) and vartd (variation in taxonomic distinctness) (clarke & warwick 2001). the taxonomic diversity measures differ from other metrics of species richness and species diversity, because they include information on the taxonomic position of species. avtd describes the average taxonomic distance (the “path length” between two species following linnean taxonomy) of all the species in the association. vartd is defined as the variance of the taxonomic distances between all pairs of species in the association. five taxonomic levels were used in calculations: species, genus, family, order and class, and equal step levels between successive taxonomic levels were assumed. the differences between soft-bottom associations in avtd and vartd were identified with the use of a one-way anova. the post-hoc testing was carried out using fisher’s lsd tests. results the material contained 35 398 individual molluscs representing 87 species of 56 genera and 43 families. one species of caudofoveata, five species of polyplacophora, 38 species of gastropoda and 43 species of bivalvia were recorded. a full taxonomic list is presented in the appendix. the species accumulation curves tended to stabilize towards an asymptotic value in the cases of both the observed and the estimated numbers of species (fig. 2). the mm estimator of the asymptotic value of total species richness gave 93 species. chao2 gave an estimate of 99 species (with 95% confidence intervals from 93 to 117). the shallow waters of the kongsbreen glacial bay were very poor in the numbers of molluscs: samples collected by scuba-diving at 10 m and in baited traps deployed at depths from 5 to 50 m yielded no mollusc specimens. samples collected with small dredges at 5–15 m contained only a few specimens. samples from baited traps located along the coast in the central and outer parts of the fjord contained only scavenging buccinid gastropods (buccinum glaciale, b. undatum, b. scalariforme, b. polare and colus kroeyeri). species–environment relationship in the cca of qualitative data the first two ordination axes explained about 50% of the variance of the species– environment relationship. the first canonical axis was significant at p = 0.002, the second axis was not significant (p > 0.05). the occurrence of rock and mud was significantly correlated to the first axis (0.85 and −0.80, respectively, fig. 3). five variables were selected as significant predictors of species distribution by the forward selection analyses: rock, depth, mud, gravel and sand (table 2). two groups of species can be delineated on the cca diagram: species situated on the left-hand side of the diagram with an occurrence restricted to muddy sediments (y. solidula, y. lenticula, thyasira dunbari, nuculana pernula, ciliatocardium ciliatum, frigidoalvania cruenta, ennucula tenuis, arctinula groenlandica and y. hyperborea); species situated on right-hand side of the plot, with an figure 2 species accumulation curves plotted for observed number of species (sobs) and the true number of species estimated using chao2 and the michaelis-menten (mm) equation. sobs and chao2 are plotted with 0.95 confidence intervals.samples sobs chao2 mm n u m b e r o f sp e ci e s 140 120 100 80 60 40 20 20 40 60 80 100 120 140 160 m. wlodarska-kowalczuk molluscs in kongsfjorden (spitsbergen, svalbard) polar research 26 (2007) 48 – 63 © 2007 the author 53 affinity to occurrence at the hard bottom (erginus rubellus, margarites groenlandicus, tonicella rubra, t. marmorea, buccinum glaciale, puncturella noachina, oenopota pyramidalis, mysella sovaliki and moelleria costulata). margarites helicinus was placed close to the kelp variable centroid. bathyarca glacialis and frigidoalvania janmayeni were located close to the drop stones centroid. in the rda of grab data the first two ordination axes were significant (p = 0.002) and explained about 89% of the variance of the species–environment relationship. a third axis was not significant (p > 0.05). the concentration of silt (0.68) and the longitude (0.62) had the highest positive correlation to the first axis (fig. 4a). the salinity at the bottom was negatively correlated to the first axis (−0.63). the temperature at the bottom was negatively correlated to the second axis (−0.63). forward selection, applied to the full set of environmental variables considered, discriminated 10 variables with significant conditional effects (table 2). the small conditional effect of longitude, temperature, salinity and sand compared with their large marginal effect results from the high correlation of these variables to silt concentration. the extra fit of the variables mentioned above is very small, as a large part of the effect is already explained by a strongly covarying variable: silt. five environmental variables were selected in repeated forward selection analyses by progressive elimination of the variables with non-significant conditional effects: silt, temperature, mineral and organic suspensions and poc/pon in sediments. three groups of species can be distinguished on the rda diagram: (1) species that correlated positively with silt, mineral suspensions and longitude (y. solidula, y. lenticula and t. dunbari); (2) species that correlated negatively with longitude (distance along the fjord) and its co-variables (lepeta caeca, margarites costalis and ischnochiton albus); (3) species not correlated to environmental variables considered in the analyses (mya truncata, y. hyperborea and t. gouldi). molluscan associations four groups of stations were distinguished on the dendrogram resulting from clustering the presence/absence data from samples taken by qualitative methods (fig. 5): (1) rock, samples collected at shallow stations (5–20 m) situated on rocky shelves at two kongsfjorden capes figure 3 ordination diagram based on the canonical correspondence analyses of mollusc species occurrences with respect to environmental variables in kongsforden. circles represent centroids of dummy variables, arrows are linear variables and triangles are species. only species with a 10% minimum fit to the lower axis are plotted. the species names are coded by the first three letters of the generic and specific name (for species names consult the appendix). 1 .0 1.0-0.6 -1 .0 yol sol yol lenfri cru cil cil nuc per arc groenn ten yol hyp fri jan bat gla cre dec moe cos mys sov oen pyr pun noa buc gla erg rub mus dis mar gro hia arc bor cas mar hel ton rub ton mar thy dun rock kelp dropdepth gravel mud longitude sand stones table 2 marginal and conditional effects obtained from the forward selection of environmental variables. λ1 is a fit with an eigen value with one variable only, λa is an additional fit with an increase in the eigen value, p is the significance level obtained with a monte carlo simulation using 499 unrestricted permutations. variable marginal effects conditional effects pλ1 λa qualitative data rock 0.52 0.52 0.002 depth 0.31 0.26 0.012 mud 0.49 0.21 0.034 gravel 0.25 0.21 0.022 sand 0.25 0.2 0.034 kelp 0.14 0.14 0.102 longitude 0.31 0.13 0.08 drop stones 0.23 0.08 0.574 grab data silt 0.29 0.29 0.002 temperature 0.28 0.08 0.004 mineral suspensions 0.13 0.13 0.002 depth 0.16 0.05 0.004 poc/pon 0.02 0.03 0.018 organic suspensions 0.14 0.04 0.004 drop stones 0.03 0.02 0.066 salinity 0.22 0.03 0.018 gravel 0.10 0.03 0.022 poc 0.19 0.05 0.002 longitude 0.26 0.03 0.008 sand 0.26 0.02 0.002 mean grain size 0.10 0.01 0.04 poc, particulate organic carbon concentration in sediment; pon, particulate organic concentration in sediment. 54 polar research 26 (2007) 48 – 63 © 2007 the author molluscs in kongsfjorden (spitsbergen, svalbard) m. wlodarska-kowalczuk (kvadehuken and kapp guissez); (2) kelp, samples collected in the shallow sublittoral on different types of bottom covered with kelp (l. saccharina, l. digitata and a. esculenta); (3) sediment, samples collected on soft bottom at depths ranging from 5 to 300 m; and (4) gravel, samples collected on gravel/stones at the entrance of the fjord (depths below 150 m). there were six species characteristic for the rock association: the chitons t. rubra and t. marmorea; the gastropods m. costulata, p. noachina and m. groenlandicus; and the bivalves crenella decussata and m. sovaliki (table 3). only the gastropod m. helicinus could be classified as characteristic for the group of samples collected at sites with kelp. the gastropods lepeta caeca, margarites costalis and trophon clathratus and the chiton ischnochiton albus were characteristic for the gravel association. thirteen species could be identified as characteristic for the sediment association (table 3). five groups of samples could be distinguished on the dendrogram of bray-curtis similarities of square-root transformed quantitative data (fig. 6): (1) g1, samples collected in the kongsbreen glacial bay; (2) g2, samples collected in the blomstrandbreen glacial bay; (3) cb, samples collected in the central basin; (4) cd, a small number of stations in the central basin where drop stones were common; (5) ce, samples from three stations situated at the mouth of the fjord. the molluscs of the kongsbreen glacial bay (g1) were dominated by the bivalves y. solidula, y. lenticula and t. dunbari (table 4). both species of yoldiella were also numerous in the glacial bay of the blomstranbreen (g2), but the characteristic species of this association included only y. hyperborea, a. orbiculata and thyasira gouldi. all the species already mentioned were also present, although much less numerous, in the cb association, where chaetoderma nitidulum was the characteristic species. b. glacialis figure 4 ordination diagram based on redundancy analyses of square root transformed mollusc species densities in grab samples with respect to environmental variables. circles represent centroids of dummy variables, small arrowheads indicate species and large arrowheads indicate linear variables. only species with a 5% minimum fit to the lower axis are plotted. the species names are coded by the first three letters of the generic and specific name (for species names consult the appendix). poc, particulate organic carbon concentration in sediments; poc/pon, particulate organic carbon/particulate organic nitrogen ratio; mz, mean grain size in sediments. -1.0 1.0 -1 .0 1. 0 axi orb yol hyp mya tru thy gou nuc per yol sol yol len thy dun arc gro cus subcyl occ yol luc longitude silt mz mineral suspensions organic suspensions poc/pon clay salinity gravel poc depthsand temperature drop-stones mac cal fri cru isc alb mar cos lep cae figure 5 distribution of associations distinguished on a dendrogram, plotted using the group average linking of bray-curtis similarities of presence/absence data of species occurrences in samples taken using qualitative methods (dredges and scuba-diving). the simplified dendrogram is presented. sediment kelp rock gravel bray-curtis similarity (%) 40 80 0 kelp rock gravel sediment m. wlodarska-kowalczuk molluscs in kongsfjorden (spitsbergen, svalbard) polar research 26 (2007) 48 – 63 © 2007 the author 55 table 3 the most common species in associations distinguished in multivariate analyses of qualitative data. f is frequency (%), ni is number of all individuals. species with frequency exceeding 25% are presented. characteristic species [degree of association regarding stations (das) exceeding 50%] are in boldface. rock kelp gravel sediment ni f ni f ni f ni f tonicella rubra 113 78 1 5 1 17 1 3 crenella decussata 92 33 2 3 moelleria costulata 48 33 1 3 mysella sovaliki 51 33 puncturella noachina 8 33 margarites groenlandicus 14 78 12 25 32 3 astarte borealis 34 33 35 15 cingula castanea 11 33 3 5 3 5 erginus rubellus 90 89 19 35 2 3 hiatella arctica 45 89 18 35 29 67 44 28 tonicella marmorea 39 56 5 5 48 33 margarites helicinus 11 22 3316 95 15 10 lepeta caeca 16 83 astarte montagui 6 50 69 20 margarites costalis 2 33 ischnochiton albus 13 22 13 17 trophon clathratus 2 33 1 3 yoldiella solidula 1 17 2479 68 yoldiella lenticula 7333 73 nuculana pernula 1837 78 arctinula groenlandica 869 63 mya truncata 34 33 7 20 351 60 ennucula tenuis 1 11 1 5 1448 55 ciliatocardium ciliatum 219 50 thyasira dunbari 418 43 frigidoalvania cruenta 6 17 344 40 axinopsida orbiculata 15 22 1129 38 bathyarca glacialis 5 17 304 38 macoma calcarea 2 11 12 17 302 33 cuspidaria subtorta 381 28 figure 6 distribution of associations distinguished on a dendrogram, plotted using the group average linking of bray-curtis similarities of square root transformed densities of species in quantitative samples from the soft bottom. the simplified dendrogram is presented. glacial bays associations central basin associations g1 g2 cd cb ce b ra yc u rt is s im ila ri ty ( % ) 40 80 0 g1 g2 cdcb ce 56 polar research 26 (2007) 48 – 63 © 2007 the author molluscs in kongsfjorden (spitsbergen, svalbard) m. wlodarska-kowalczuk was both the most abundant and characteristic species in the cd association, whereas the gastropod l. caeca was characteristic for the ce association. e. tenuis, n. pernula and macoma calcarea were not characteristic for any of the associations—they were common in soft sediments all over the fjord. density and diversity in the quantitative samples from the soft bottom the number of individuals (n) was significantly higher in the glacial bays (214 ind./0.1 m2 on average in g1, 387 ind./0.1 m2 in g2) than in the central basin associations (32 ind./0.1 m2 in cb, 40 ind./0.1 m2 in cd, 27 ind./ 0.1 m2 in ce; fig. 7). sp was at the highest level and significantly different from most other assemblages in g2 (fig. 7; table 5). h was higher in g2, cb and cd than in g1 and ce. j was lower in glacial bays (g1 and g2) than in the central basin assemblages, cb, cd and ce. avtd was significantly lower in glacial bays (g1 and g2) than in the central basin assemblages (cb, cd and ce; fig. 7; table 5). there was no significant difference in vartd at p < 0.05 (one-way anova). discussion the survey of kongsfjorden molluscs yielded 87 mollusc species. rozycki (1991) reported 39 mollusc species in 18 samples collected in kongsfjorden in 1988. his list included nine species (littorina saxatilis, nucella lapillus, table 4 the dominant species in mollusc associations at the soft bottom. d is dominance (%), avn is average density (ind./0.1 m2). the five most abundant species are presented for each association. characteristic species [either degree of association regarding individuals (dai) or das > 60%] are in boldface. g1 g2 cb cd ce avn d avn d av n d avn d avn d yoldiella solidula 116.0 54 24.2 6 5.2 16 0.3 1 0.3 1 yoldiella lenticula 53.0 25 9.0 2 7.7 24 0.5 2 0.1 1 thyasira dunbari 24.7 12 1.0 0 0.2 1 0.3 1 0.1 1 ennucula tenuis 8.7 4 29.0 8 2.3 7 1.1 4 nuculana pernula 3.6 2 15.8 4 2.7 8 0.9 3 axinopsida orbiculata 1.0 1 177.2 46 0.6 2 0.5 2 yoldia hyperborea 0.1 0 48.3 13 0.2 1 thyasira gouldi 48.2 12 0.1 0 2.8 10 macoma calcarea 0.1 0 8.7 2 0.2 1 8.3 30 frigidoalvania cruenta 0.5 0 6.3 2 2.0 6 chaetoderma nitidulum 0.9 0 0.7 0 3.7 11 1.8 6 1.1 4 bathyarca glacialis 0.1 0 2.3 7 23.3 78 frigidoalvania janmayeni 1.4 4 2.0 7 oenopota sp. 0.0 0 0.4 1 1.5 5 lepeta caeca 0.7 2 8.0 29 figure 7 density (n, number of individuals per 0.1 m2) and diversity (sp, number of species per sample; h, shannon-wiener index; j, pielou index; avtd, average taxonomic distinctness; vartd, variance of taxonomic distinctness) in mollusc assemblages of the soft bottom (mean and 95% confidence intervals). s p n ( in d ./ 0 .1 m 2 ) 100 300 500 6 10 14 18 1.2 1.6 2.0 h j 0.6 0.7 0.8 0.9 a vt d va rt d 60 64 68 72 76 160 240 320 g1 g1g2 g2cb cbcd cdce ce glacial bays glacial bayscentral basin central basin associations associations m. wlodarska-kowalczuk molluscs in kongsfjorden (spitsbergen, svalbard) polar research 26 (2007) 48 – 63 © 2007 the author 57 buccinum hydrophanum, colus latericus, turbonilla interrupta, thyasira ferruginea, macoma loveni, kellyella miliaris and poromya subtorta) that were absent in material i have studied here. combining the data, there have been 96 species recorded in kongsfjorden to date. this number of species lies within the confidence interval of the chao2 estimate of the true species richness in the fjord, and is a quarter of all the arctic species (436 species of molluscs, excluding nudibranchia and cephalopoda) listed by sirenko (2001). it is difficult to compare the assessment of konsfjorden molluscan species richness to other arctic localities as there are few studies of comparative sampling effort covering the full range of fjordic habitats and depths. seventy nine mollusc species were identified in 106 benthic samples collected with the use of grabs and dredges at depths from 2 to 190 m in jørgen brønlund fjord, north greenland (schiøtte 1989). only 26 mollusc species were found in 27 dredge samples in expedition fiord, northwest territories, canada (aitken & gilbert 1996). odhner (1915) recorded 130 mollusc species (cephalopods and nudibranchs excluded) in a comprehensive study of isfjorden (west spitsbergen) based on 130 stations sampled with various dredges at depths ranging from 2 to 406 m. rozycki (1993) added another nine bivalve species to odhner’s list. isfjorden is about four times longer and much larger in area than kongsfjorden, so it can host a higher number of species, but its species richness is nevertheless dramatically lower than that found in lower latitude sites of a similar area. a species inventory of a tropical coastal site with an area of 295 km2 off the coast of new caledonia recorded as many as 2738 species of marine molluscs (bouchet et al. 2002). the differences between the mollusc species richness in polar and tropical sites are enormous. the huge latitudinal cline of diversity, more pronounced in molluscs than in some other taxa, may be related to the increased cost of calcification in low temperatures, as suggested by clarke (1992). the majority of mollusc species in kongsfjorden showed strong preferences towards a single substratum type; only a few (e.g. hiatella arctica and mya truncata) were abundant both on soft and hard substrata. the major discontinuity in mollusc species distributions separated the biota of rocky shelves, gravel beds and the soft bottom. multivariate analyses distinguished the kelp associated fauna as the fourth association, but kelp bed samples differed from the rocky shelf material mostly in the common occurrence and dominance of m. helicinus, a well-known dweller of kelp cauloids and phylloids in the shallow waters of spitsbergen (rozycki & gruszczynski 1986). the substrate dictates the taxonomic and functional organization of mollusc associations. the rocky shelf fauna is dominated by grazing chitons (tonicella) and gastropods (erginus and margarites), and suspension feeding sedentary bivalves (crenella, astarte and hiatella), the gravel beds are inhabited by grazers, surface deposit feeders and suspension feeders (ischnochiton, lepeta and astarte), whereas mobile deposit feeding bivalves (yoldiella, yoldia, nuculana, ennucula and axinopxida) dominate in soft sediments. such distribution of functional groups agrees well with the model patterns described for boreal coastal macrobenthic communities by pearson & rosenberg (1987). five separate assemblages distinguished in soft sediments could be regarded as different expressions of the same species pool, as any differences were largely a result of the varying patterns of dominance of the same set of species. the changes in the relative dominance of the infaunal molluscs could be largely explained in terms of the distance that any particular assemblage lies from the head of the fjord and from the most active glacier, kongsbreen. although rda analysis showed that there are many factors that were related to the distribution of faunal assemblages, the significant factors were co-variable and the overall influence of the glacier was predominant. the granulometric characteristics, the quantity of organic carbon and the stability of sediments all reflect the glacial sedimentation gradients in an arctic glacial fjord (gorlich et al. 1987; syvitski et al. 1987; wlodarska-kowalczuk & pearson 2004). similarly the salinity and temperature gradients are produced by the inflow of fresh and cold glacial meltwaters, and are controlled by the glacier activity (svendsen et al. 2002). high levels of mineral sedimentation and sediment deposition have been shown to be an acute disturbance agent causing a dramatic decrease in benthic densities and diversity (e.g. airoldi 2003; anderson et al. 2004; thrush et al. 2004; wlodarska-kowalczuk et al. 2005). arctic molluscs cope surprisingly well with the glacial table 5 results of kruskal-wallis test comparing density (n, number of individuals per 0.1 m2) and anova comparing diversity measures (sp is the number of species per sample, h is shannon-wiener index, j is pielou index, avtd is average taxonomic distinctness, vartd is variance of taxonomic distinctness) of mollusc associations at the soft bottom. pairwise contrasts determined by mann-whitney u tests for n and post-hoc fisher’s lsd tests for sp, h, j and avtd. g1 and g2 are glacial bay associations, cb, ce and cd are central basin associations. f or h p significant contrasts in pairs of assemblages (at p < 0.05) n 47.5 (h) 0.000 g1, g2 > cb,cd,ce; g2 > g1 sp 13.0 (f ) 0.000 g2 > g1,cb,cd,ce; g1,cd > ce; cd > cb h 9.4 (f ) 0.000 g1 < cb,cd,g2; cb < cd; cd,g2 > ce j 13.9 (f ) 0.000 g1, g2 < cb,cd, ce avtd 17.2 (f ) 0.000 g1,g2 < cb,cd, ce vartd 1.1 (f ) 0.382 — 58 polar research 26 (2007) 48 – 63 © 2007 the author molluscs in kongsfjorden (spitsbergen, svalbard) m. wlodarska-kowalczuk sedimentation disturbance. in kongsfjorden, the mollusc numbers are ten times higher in glacial bays than in the stable sediments of the central basin because of the high abundance of a few species of yoldiella and thyasira. protobranch bivalves are the most common dominants in the sediments influenced by either glacial or glaciofluvial inputs in several other arctic and sub-arctic sites, whereas suspension feeding bivalves astarte, hiatella and bathyarca seem to prefer the outer basins of fjords of high latitude (table 6). several yoldiella species (y. intermedia, y. fraterna and y. lenticula) were also reported as pioneer species populating defaunated sediments in succession following the onset of deglaciacion in late pleistocene shelf sediments off the coast of northern norway (thomsen & vorren 1986). this pioneer community was later replaced by an “established low-arctic community” comprising b. glacialis, astarte crenata, frigidoalavania janmayeni, t. gouldi and a. groenlandica (thomsen & vorren 1986). the common features of yoldiid and thyasirid bivalves successful in glacial bays include small, simple, smooth and thin shells with no external ornamentation, which facilitate movement and the maintenance of the proper position in unstable quickly accumulating sediments (rhoads 1974). yoldiid bivalves possess a large and muscular foot and are known to move into and through a soft substratum (yonge 1939). they collect detritus particles from the sediment surface with the use of long palp proboscides, and can very efficiently sort the particles (stasek 1965). the efficient mechanism of elimination of pseudofaeces protects the respiratory organs of protobranch bivalves from being clogged by mineral particles accumulating in the mantle cavity (rhoads 1974). all of these traits of yoldiid bivalves (small size, high mobility, selective deposit feeding and the efficient elimination of mineral particles) obviously facilitate their survival in glacial bays. what makes thyasirids well-suited to high sedimentation and instable sediments is less clear. some thyasira species construct a complicated system of mucus-lined tunnels, host symbiotic chemoautotrophic bacteria and are nutritionally dependent on hydrogen sulphides in sediments (dando & southward 1986; dando & spiro 1993). the spitsbergen fjordic sediments are well oxygenated (jorgensen et al. 2005), and the local thyasirids must depend on energy sources other than energy derived from the oxidation of sulphur compounds. the high sedimentation does not favour the construction of stable tunnels. the life habits of the kongsfjorden thyasirid dominant species must differ from those of the temperate atlantic species described by dando & southward (1986) and dando & spiro (1993). the dominants in two kongsfjorden glacial bays are different, although closely related: y. solidula and t. dunbari in kongsbreen glacial bay (g1) and y. hyperborea, a. orbiculata and t. gouldi in blomstrandbreen glacial bay (g2). the blomstrandbreen glacial bay is located closer to the fjord mouth and has a much higher concentration of organic matter in the sediments than the sediments of kongsbreen glacial bay (wlodarska-kowalczuk & pearson 2004). wlodarska-kowalczuk et al. (1998) reported the similar separation of protobrach bivalves in a survey of six west spitsbergen glacial bays—y. hyperborea domination in two locations situated at either the open coast or close to the fjord mouth and yoldiella solidula (erroneously identified as yoldiella fraterna) in four sites situated in inner fjord basins. ockelmann (1958) suggested that y. hyperborea has fairly high energetic demands and therefore occurs primarily at either the open coast or in the outer parts of the fjords, where the supply of organic matter is larger than in the inner fjord basins. domination by y. hyperborea was reported for open shelf waters influtable 6 dominant mollusc taxa in subtidal sediments in inner (either glacial or glaciofluvial sedimentation influenced) basins versus outer parts of arctic fjords. location inner fjord outer fjord expedition fiord, northwestern territories, canada (aitken & gilbert 1996) portlandia arctica, thyasira gouldi astarte borealis, astarte warhami, hiatella arctica, mya sp., trichotropis sp. mcbeth and itirbilung fiords (syvitski et al. 1989, aitken& fournier 1993) portlandia arctica, hiatella arctica, axinopsida orbiculata axinopsida orbiculata, bathyarca glacialis, astarte spp. cambridge fiord (aitken & fournier 1993) yoldiella intermedia, yoldiella lenticula, axinopsida orbiculata axinopsida orbiculata, bathyarca glacialis, astarte spp. yoldiabukta, isfjorden, spitsbergen (wlodarskakowalczuk et al. 1999) yoldiella fraterna — hornsund, unpublished data portlandia arctica ennucula tenuis, ciliatocardium ciliatum van mijenfjorden, svalbard (gulliksen et al. 1985, renaud et al. 2007) portlandia arctica, yoldiella solidula macoma calcarea jørgen brønlund fjord, north greenland (schiøtte 1989) portlandia arctica hiatella arctica scoresby sund, greenland (thorson 1934) portlandia arctica astarte crenata, bathyarca glacialis young sound, east greenland (sejr et al. 2000) — astarte spp., hiatella arctica m. wlodarska-kowalczuk molluscs in kongsfjorden (spitsbergen, svalbard) polar research 26 (2007) 48 – 63 © 2007 the author 59 enced by the terrigenous inflows off svalbard (wlodarska et al. 1996), as well as off southern greenland and iceland (peres 1982). similarly, t. gouldi was reported to occur in large numbers in chukchi sea shelf sediments (feder et al. 1994), and may be less suited to survival in inner basin glacial bay sediments that are poor in organic matter. the yoldiid and thyasirid bivalves occurred at most stations with soft bottoms in kongsfjorden, but it was only in glacial bays that these species were found in large numbers. in central basins, in stable conditions with low inorganic sedimentation, the bivalves are replaced by numerous tube-building polychaetes (maldane sarsi and spiochaetopterus typicus; wlodarska-kowalczuk & pearson 2004). the same pattern is observed in canadian fjords: portlandia arctica is present in large numbers only near glaciers and is much less numerous in central and outer fjord basins inhabited by maldanid association (syvitski et al. 1989; aitken & fournier 1993). the dense populations of tube-building polychaetes can diminish the numbers of mobile burrowers as a result of the competition for space and food (wilson 1991). the experimental removal of tube builders results in the dramatic increase in numbers of mobile detritus feeders (woodin 1974). the high densities of protobranch and thyasirid bivalves in glacial bays may result from the competitive release, as the tube builders are naturally eliminated by high sedimentation and the deposition of mineral material. the weak competitive capabilities of protobranchia were expressed in the evolutionary history of the group. protobranchia are numerically dominant and are the most diverse deep sea bivalves known at present (allen & sanders 1996). during the mesozoic the atlantic protobranchia migrated to the deep sea as a consequence of competitive exclusion by the eulamellibranch bivalves radiating at that time in shallow waters (allen 1978). the patterns of mollusc distribution at the soft bottom and diversity in kongsfjorden are not fully consistent with those of the whole macrobenthic community described by wlodarska-kowalczuk et al. (2005). the main discontinuity in patterns of both complete macrobenthos and mollusc species distribution separates the glacial bays and central basin stable sediments, but the dramatic species diversity cline towards the glaciers described for the whole macrofauna was not observed in mollusc assemblages. the high increase of numbers of individuals in assemblages near glaciers was also a pattern unique to molluscs. the taxonomic distinctness showed the contrasting patterns along the glacial sedimentation gradient. avtd drops for molluscs, but increases for the whole macrobenthic community the closer one gets to the glacier. it is noteworthy that the discrepancies in taxonomic distinctness patterns for different taxonomic groups may result from different responses to environmental gradients, but also from differences in the hierarchical taxonomic systems of different phyla (ellingsen et al. 2005). smith (2005) observed the high correlation of mollusc diversity and the overall benthic community diversity on rocky shores, and recommended using molluscs as surrogates for complete macrobenthic communities in benthic diversity and impact assessment studies. however, the molluscs of the soft bottom seem to react to glacial disturbance in a different way than do other benthic phyla and i would not recommend molluscs as a useful surrogate for the whole macrobenthic community in surveys of sedimentary habitats. acknowledgements the samples used in this study came from several sampling campaigns. i would like to thank dr j. lege y ska, dr m. zaj czkowski and all colleagues involved in the field work. dr j. lege y ska and dr p. kukli ski provided samples from baited traps and diving surveys, which is gratefully acknowledged. i wish to thank dr a. warèn for the verification of mollusc identifications and for valuable comments. my visits to the swedish natural history museum in stockholm and the zoological museum in copenhagen were supported by the highlat project (hpri-ct-2001-0125) and the cobice project (hprict-1999-00021). i wish to thank dr k. blachowiaksamolyk for help with statistical analyses. i am very grateful to dr m.a. kendall, prof. j.m. w slawski and the two anonymous referees whose comments much improved the manuscript. the study has been completed thanks to funds provided by grant pbz-kbn-108/p04/ 2004 from the polish national committee for scientific research. the author acknowledges the support by the marbef network of excellence project marine biodiversity and ecosystem functioning, which is funded by the sustainable development, global change and ecosystems programme of the european community’s sixth framework programme (contract no. goce-ct-2003505446). this publication is contribution number mps06039 of marbef and a contribution to the marbef responsive mode programme arcteco. references airoldi l. 2003. the effects of sedimentation on rocky coast assemblages. oceanography and marine biology annual review 41, 161–236. aitken a.e. 1990. fossilization potential of arctic fjord and continental shelf benthic macrofaunas. in j.a. dowdeswell & j.d. scourse (eds.): glacimarine environments: processes and sediments. geological society of london special publication no 53. pp. 155–176. london: geological society. ż n¢ a̧ ż n¢ n¢ ȩ 60 polar research 26 (2007) 48 – 63 © 2007 the author molluscs in kongsfjorden (spitsbergen, svalbard) m. wlodarska-kowalczuk aitken a.e. & fournier j. 1993. macrobenthos communities of cambridge, mcbeth and itirbilung fiords, baffin island, northwest territories, canada. arctic 46, 60–71. aitken a.e. & gilbert r. 1996. marine mollusca from expedition fiord, western axel heiberg island, northwest territories. arctic 49, 29–43. allen j.a. 1978. evolution of the deep sea protobranch bivalves. philosophical transactions of the royal society of london 284, 387–401. allen j.a. & sanders h.l. 1996. the zoogeography, diversity and origin of the deep-sea protobranch bivalves of the atlantic: the epilogue. progress in oceanography 38, 95–153. anderson m.j., diebel c.e., blom w.m. & landers t.j. 2005. consistency and variation in kelp holdfast assemblages: spatial patterns of biodiversity for the major phyla at different taxonomic resolutions. journal of experimental marine biology and ecology 320, 35–56. anderson m.j., ford r.b., feary d.a. & honeywill c. 2004. quantitative measures of sedimentation in an estuarine system, and its relationship with intertidal soft-sediment infauna. marine ecology progress series 272, 33–48. bick a. & arlt g. 2005. intertidal and subtidal soft-bottom macro-and meiofauna of the kongsfjord (spitsbergen). polar biology 28, 550–557. bouchet p., louzet p., maestrati p. & heros v. 2002. assessing the magnitude of species richness in tropical marine environments: exceptionally high numbers of molluscs at a new caledonia site. biological journal of the linnean society 75, 421– 436. chao a. 1987. estimating the population size for capturerecapture data with unequal catchability. biometrics 43, 783– 791. chao a. 2004. species richness estimation. in n. balakrishnan et al. (eds.): encyclopedia of statistical sciences. pp. 1–23. new york: wiley. clarke a. 1992. is there a latitudinal diversity cline in the sea? trends in ecology and evolution 7, 286–287. clarke k.r. & warwick r.m. 2001. a further biodiversity index applicable to species lists: variation in taxonomic distinctness. marine ecology progress series 216, 265–278. colwell r.k. 2005. estimates: statistical estimation of species of richness and shared species from samples. version 7.5 users guide: http://purl.oclc.org/estimates. colwell r.k., mao c.x. & chang j. 2004. interpolating, extrapolating, and comparing incidence-based species accumulation curves. ecology 85, 2717–2727. dale j.e., aitken a.e., gilbert r. & risk m.j. 1989. macrofauna of canadian arctic fjords. marine geology 85, 331–358. dando p.r. & southward a.j. 1986. chemoautotrophy in bivalve molluscs of the genus thyasira. journal of the marine biological association of the united kingdom 66, 915–929. dando p.r. & spiro b. 1993. varying nutritional dependence of the thyasirid bivalves thyasira sarsi and t. equalis on chemoautotrophic symbiotic bacteria, demonstrated by isotope ratios of tissue carbon and shell carbonate. marine ecology progress series 92, 151–158. dowdeswell j.a. & forsberg c.f. 1992. the size and frequency of icebergs and bergy bits derived from tidewater glaciers in kongsfjorden. northwest spitsberger. polar res 11, 81–91. ellingsen k.e., clarke k.r., somerfield p.j. & warwick r.m. 2005. taxonomic distinctness as a measure of diversity applied over a large scale: the benthos of the norwegian continental shelf. journal of animal ecology 74, 1069–1079. feder h.m., foster n.r., jewett s.c., weingartner t.j. & baxter r. 1994. mollusks in the northeastern chukchi sea. arctic 47, 145–163. fetzer i., lonne o.j. & pearson t. 2002. the distribution of juvenile benthic invertebrates in an arctic glacial fjord. polar biology 25, 303–315. gordillo s. & aitken a.e. 2000. palaeoenvironmental interpretation of late quaternary marine molluscan assemblages, canadian arctic archipelago. geographie physique et quaternaire 54, 301–315. gorlich k., weslawski j.m. & zajaczkowski m. 1987. suspension settling effect on macrobenthos biomass distribution in the hornsund fjord, spitsbergen. polar research 5, 175–192. gulliksen b., holte b. & jakola k.j. 1985. the soft-bottom fauna in van mijenfjord and raudfjord, svalbard. in j. gray & m.e. christiansen (eds.): marine biology of polar regions and effects of stress on marine organisms. pp. 199–215. oslo: john wiley and sons. hop h., pearson t.h., hegseth e.n., kovacs k.m., wiencke c., kwasniewski s., eiane k., mehlum f., gulliksen b., wlodarska-kowalczuk m., lydersen c., weslawski j.m., cochrane s., gabrielsen g.w., leakey r., lonne o.j., zajaczkowski m., falk-petersen s., kendall m.a., wängberg s.-å., bischof k., voronkov a., kovaltchouk n.a., wiktor j., poltermann m., di prisco g., papucci c. & gerland s. 2002. the marine ecosystem of kongsfjorden, svalbard. polar research 21, 167–208. jorgensen b.b., glud r.n. & holby o. 2005. oxygen distribution and bioirrigation in arctic fjord sediments (svalbard, barents sea). marine ecology–progress series 292, 85–95. jorgensen l.l. & gulliksen b. 2001. rocky bottom fauna in arctic kongsfjord (svalbard) studied by means of suction sampling and photography. polar biology 24, 113–121. kaczmarek h., wlodarska-kowalczuk, m., legezynska j. & zajaczkowski m. 2005. shallow sublittoral macrozoobenthos in kongsfjord, west spitsbergen, svalbard. polish polar research 26, 137–155. kendall m.a., widdicombe s. & weslawski j.m. 2003. a multiscale study of the biodiversity of the benthic infauna of the high-latitude kongsfjord, svalbard. polar biology 26, 383– 388. kuklinski p. & porter j.s. 2004. alcyonidium disciforme: an exceptional arctic bryozoan. journal of the marine biological association of the united kingdom 84, 267–275. lefauconnier b., hagen j.o. & rudant j.p. 1994. flow speed and calving rate of kongsbreen glacier, svalbard, using spot images. polar research 13, 59–65. legezynska j. 2001. distribution patterns and feeding strategies of lyssianassid amphipods in shallow waters of an arctic fjord. polish polar research 22, 173–186. http://purl.oclc.org/estimates m. wlodarska-kowalczuk molluscs in kongsfjorden (spitsbergen, svalbard) polar research 26 (2007) 48 – 63 © 2007 the author 61 legezynska j. 2002. ekologia padlinozernych bezkregowcow w arktycznym fiordzie. (ecology of scavenging invertebrates in an arctic fjord.) phd thesis, university of gdansk, poland. lippert h., iken k., rachor e. & wiencke c. 2001. macrofauna associated with macroalgae in the kongsfjord (spitsbergen). polar biology 24, 512–522. magurran a.e. 2004. measuring biological diversity. malden, ma: blackwell publishing. mieszkowska n., kendall m.a., hawkins s.j., leaper r., williamson p., hardman-mountford n.j. & southward a.j. 2006. changes in the range of some common rocky shore species in britain—a response to climate change? hydrobiologia 555, 241–251. ockelmann k.w. 1958. marine lamellibranchiata. meddelelser om gronland 122. odhner n.h. 1915. die molluskenfauna des eisfjordes. kungliga svenska vetenskapsakasemiens handligar 54. pearson t.h. & rosenberg r. 1987. feast and famine: structuring factors in marine benthic communities. in j.h.r. gee & p.s. giller (eds.): organization of communities. past and present. pp. 373–95. oxford, uk: blackwell science. peres j.m. 1982. major benthic assemblages. in o. kinne (ed.): marine ecology. vol. v. pp. 373–522. new york: john wiley and sons. renaud p.e., wlodarska-kowalczuk, m., trannum h., holte b., weslawski j.m., cochrane s., dahle s. & gulliksen b. 2007. multidecadal stability of benthic community structure in a high-arctic glacial fjord (van mijenfjord, spitsbergen). polar biology 30, 295–305. rhoads d.c. 1974. organism-sediment relations on the muddy sea floor. oceanography and marine biology annual review 12, 263–300. rozycki o. 1991. benthic molluscs of kongsfjorden (svalbard). in j. repielewska-pekalowa & k. pekala (eds.): wyprawy geograficzne na spitsbergen. (geographic expeditions to spitsbergen.) pp. 289–295. lublin, poland: umcs. rozycki o. 1993. shallow-water molluscs of isfjorden (west spitsbergen, svalbard). polish polar research 14, 55–63. rozycki o. & gruszczynski m. 1986. macrofauna associated with laminarians in the coastal waters of west spitsbergen. polish polar research 7, 337–351. salzwedel h., rachor e. & gerdes d. 1985. benthic macrofauna communities in the german bight. veroffentlichungen des instuts fur meeresforschungin bremerhaven 20, 199–267. schiøtte t. 1989. marine mollusca from jorgen bronlund fjord, north greenland, including the description of diaphana vedelsbyae n. sp. meddelelser om gronland 28, 3–24. sejr m.k., jensen k.t. & rysgaard s. 2000. macrozoobenthic community structure in a high-arctic east greenland fjord. polar biology 23, 792–801. sirenko b.i. 2001. list of species of free-living invertebrates of eurasian arctic seas and adjacent deep waters. st petersburg: zoological institute. smith s.d.a. 2005. rapid assessment of invertebrate biodiversity on rocky shores: where there’s a whelk there’s a way. biodiversity and conservation 14, 3565–3576. somerfield p.j., cochrane s.j., dahle s. & pearson t.h. 2006. free-living nematodes and macrobenthos in a high-latitude glacial fjord. journal of experimental marine biology and ecology 330, 284–296. stasek c.r. 1965. feeding and particle-sorting in yoldia ensifera (bivalvia: protobranchia) with notes on other nuculanids. malacologia 2, 349–366. stork n.e., samways m.j. & eeley h.a.c. 1996. inventorying and monitoring biodiversity. trends in ecology and evolution 11, 39–40. svendsen h., beszczynska-moller a., hagen j.o., lefauconnier b., tverberg v., gerland s., orbaek j.b., bischof k., papucci c., zajaczkowski m., azzolini r., bruland o., wiencke c., winther j.g. & dallmann w. 2002. the physical environment of kongsfjorden–krossfjorden, an arctic fjord system in svalbard. polar research 21, 133–166. syvitski j.p.m., burrell d.c. & skei j.m. 1987. fjords. processes and products. new york: springer-verlag. syvitski j.p.m., farrow g.e., atkinson r.j.a., moore p.g. & andrews j.t. 1989. baffin island fjord macrobenthos: bottom communities and environmental significance. arctic 42, 232–247. ter braak c.j.t. & smilauer p. 2002. canoco reference manual and canodraw for windows, user’s guide. wageningen and ceske budejovice: biometris. terlizzi a., scuderi d., fraschetti s. & anderson m.j. 2005. quantifying effects of pollution on biodiversity: a case study of highly diverse molluscan assemblages in the mediterranean. marine biology 148, 293–305. thomsen e. & vorren y.o. 1986. macrofaunal palaeoecology and stratigraphy in late quaternary shelf sediments off northern norway. palaeogeography, palaeoclimatology, palaeoecology 56, 103–150. thorson g. 1934. contributions to the animal ecology of the scoresby sound fjord complex (east greenland). meddelelser om gronland 100. thrush s.f., hewitt j.e., cummings v.j., ellis j.i., hatton c., lohrer a. & norkko a. 2004. muddy waters: elevating sediment input to coastal and estuarine habitats. frontiers in ecology and environment 2, 299–306. warwick r.m., emblow c., feral j.p., hummel h., van avesaath p. & heip c. 2003. european marine biodiversity research sites. report of the european concerted action: biomare. implementation and networking of large scale, long term marine biodiversity research in europe. yerseke, netherlands: netherlands institute for ecological research, centre for estuarine and marine research ecology. wilson w.h. 1991. competition and predation in marine soft-sediment communities. annual review of ecology and systematics 21, 221–241. winkelman d. & knies j. 2005. recent distribution and accumulation of organic carbon on the continental margin west of spitsbergen. geochemistry geophysics geosystems 6, 1–22. wlodarska-kowalczuk m. & pearson t.h. 2004. soft-bottom macrobenthic faunal associations and factors affecting species distributions in an arctic glacial fjord (kongsfjord, spitsbergen). polar biology 27, 155–167. 62 polar research 26 (2007) 48 – 63 © 2007 the author molluscs in kongsfjorden (spitsbergen, svalbard) m. wlodarska-kowalczuk wlodarska-kowalczuk m., pearson t.h. & kendall m.a. 2005. benthic response to chronic natural physical disturbance by glacial sedimentation in an arctic fjord. marine ecology progress series 303, 31–41. wlodarska-kowalczuk m., szymelfenig m. & kotwicki l. 1999. macroand meiobenthic fauna of the yoldiabukta glacial bay (isfjorden, spitsbergen). polish polar research 20, 367–386. wlodarska-kowalczuk m., weslawski j.m. & kotwicki l. 1998. spitsbergen glacial bays macrobenthos—a comparative study. polar biology 20, 66–73. wlodarska m., weslawski j.m. & gromisz s. 1996. a comparison of the macrofaunal community structure and diversity in two arctic glacial bays—a “cold” one off franz josef land and a “warm” one off spitsbergen. oceanologia 38, 251–283. woodin s.a. 1974. polychaete abundance patterns in a marine soft-sediment environment: the importance of biological interactions. ecological monographs 44, 171–187. yonge c.m. 1939. the protobranchiate mollusca; a functional interpretation of their structure and evolution. philosophical transactions of the royal society of london 230, 79–147. appendix list of mollusc species found in materials collected in kongsfjorden in 1996–2000. caudofoveata chaetodermatidae chaetoderma nitidulum lovén, 1844 polyplacophora leptochitonidae leptochiton arcticus (sars, g.o. 1878) leptochiton alvelous (lovén, 1846) ischnochitonidae tonicella marmorea (fabricius, o. 1780) tonicella rubra (linné, 1767) ischnochiton albus (linné, 1767) gastropoda prosobranchia fissurellidae puncturella noachina (linné, 1771) lothidae erginus rubellus (fabricius, o. 1780) lepetidae lepeta caeca (müller, 1776) trochidae margarites costalis (gould, 1841) margarites groenlandicus (gmelin, 1791) margarites helicinus (phipps, 1774) margarites olivaceus brown, 1827 solariella varicosa (mighels & adams, 1842) turbinidae moelleria costulata (møller, 1842) rissoidae frigidoalvania janmayeni (friele, 1878) frigidoalvania cruenta (odhner, 1915) boreocingula castanea (møller, 1842) elachisimidae elachisina globuloides (warén, 1972) turritellidae tachyrhynchus reticulatus (mighels & adams, 1842) naticidae euspira pallida (broderip & sowerby, g.b. 1829) cryptonatica affinis (gmelin, 1791) muricidae trophon clathratus (linné, 1767) boreotrophon truncatus (ström, 1767) buccinidae buccinum undatum (linné, 1758) buccinum scalariforme, møller, 1842 buccinum glaciale linné, 1761 buccinum polare gray j.e., 1839 colus kroeyeri (møller, 1842) colus sabini (gray, 1824) cancellaridae admete viridula (fabricius, o. 1780) conidae oenopota pyramidalis (ström, 1788) oenopota exarata (møller, 1842) oenopota impressa (mørch, 1969) oenopota nobilis (møller, 1842) oenopota sp gastropoda heterobranchia mathildidae turitellopsis stimpsoni (stimpson, 1851) pyramidellidae menestho albula (fabricius, o. 1780) menestho truncatula odhner, 1915 gastropoda opisthobranchia diaphanidae diaphana sp retusidae retusa sp. philinidae philine sp. cylichnidae cylichna cf alba (brown, 1827) cylichna cf occulta (mighels & adams, 1842) bivalvia nuculidae ennucula tenuis (montagu, 1808) nuculanidae nuculana pernula müller, 1779 nuculana minuta (müller, 1776) yoldiidae yoldia hyperborea torell, 1859 m. wlodarska-kowalczuk molluscs in kongsfjorden (spitsbergen, svalbard) polar research 26 (2007) 48 – 63 © 2007 the author 63 yoldiella solidula warén, 1989 yoldiella lucida (lovén, 1846) yoldiella lenticula (møller, 1842) yoldiella frigida (torell, 1859) yoldiella intermedia (sars, m. 1865) portlandia arctica (gray, 1824) mytilidae crenella decussata (montagu, 1808) musculus corrugatus (stimpson, 1851) musculus discors (linné, 1767) dacrydium vitreum (møller, 1842) arcidae bathyarca glacialis (gray, j.e. 1824) pectinidae chlamys islandica (müller, o.f. 1776) propeamussiidae arctinula groenlandica (sowerby, g.b. 1842) thyasiridae axinopsida orbiculata (sars, g.o. 1878) thyasira gouldi (philippi, 1845) thyasira dunbari lubinsky, 1976 thyasira sp. n. (bouchet & warén, 1979) ungulinidae diplodonta torelli jeffreys, 1847 kellidae kellia sp. montacutidae montacuta maltzani verkrüzen 1876 montacuta spitzbergensis knipowitsch, 1901 mysella sovaliki macginitie, 1959 astartidae astarte crenata (gray, 1824) astarte borealis (schumacher, 1817) astarte elliptica (brown, 1827) astarte montagui (dillwyn, 1817) cardidae ciliatocardium ciliatum (fabricius, o. 1780) serripes groenlandicus (bruguière, 1789) tellinidae macoma moesta deshayes, 1855 macoma calcarea (gmelin, 1791) veneridae liocyma fluctuosa (gould, 1841) myidae mya truncata linné, 1758 hiatellidae hiatella arctica (linné, 1767) thraciidae thracia myopsis møller, 1842 thracia devexa sars, g.o. 1878 lyonsiidae lyonsia arenosa (møller, 1842) pandoridae pandora glacialis leach, 1819 cuspidariidae cuspidaria subtorta (sars, g.o. 1878) cuspidaria arctica (sars, m. 1859) news from the plio-pleistocene kap kobenhavn formation, north greenland ole bennike bennike, 0. 1987: news from the plio-pleistocene kap ksbenhavn formation, north greenland. polar research 5 a s . , 335l3.340. ole bennike, geological museum, 0ster voldgade 5-7, dk-!350 copenhagen k , denmark. the kap kdbenhavn formation is situated in north greenland, at the shores of the arctic ocean, in an area which presently has a very sparse flora and fauna. the formation was discovered by s. funder in 1979 (funder & hjort 1980). and subsequently visited in 1980 and 1983, and last summer by the author and jens bocher who studies insect remains. virtually the whole area covered by the formation (about 300 km2) has now been investigated. the formation consists of coastal and shallow marine sand and silt, partly deposited in wave dominated deltas. it is till covered, and most sections show glaciotectonic structures. the formation is divided into a homogeneous member a and a more heterogeneous member b (funder et al. 1984). member a contains evidence of glaciation in the region. the sediments contain abundant plant and animal remains. virtually all major groups of plants and animals are represented, and they provide a detailed picture of the marine, terrestrial and limnic environments. they also, in combination with palaeomagnetic and amino acid data, date the sequence to the late pliocene and early pleistocene (abrahamsen & fig. 1 . sem photographs of some macroscopic plant remains from the kap ksbenhavn formation. a: fruit of scirpus microcarpus. x24. b: surface detail of a , x.520. c: fruit of myrica eogale/gale, x17. d: oospore of tolypella cf. nid@ca (algae), x 100. e: seed of viola sp., x28. f : cross section of picea mariana needle, x38. 340 0. bennike marcussen 1986. fevling-hanssen 1986. 1987; funder et al. 1985). i n 1986 o u r major emphasis was on the northernmost sections of the formation. these were not discovered until the end of the 1983 season. we were able to extend the stratigraphy worked out in 1983 somewhat northwards. t o the northeast we discovered an isolated exposure of a new facies. shown by amino acid ratios to correlate with the kap kabenhavn formation. whereas the previously known molluscs are extremely thin shelled possiblydue to lowered salinity this facies contains a more normal, rather rich fauna. including the snail trirhotropis birarinata which is new to the fossil fauna of greenland. no extinct mollusc species have yet been identified. jens bocher has found c. 120 species of beetles which are now being identified. most of them are extant. boreal species which d o not occur i n greenland today. apart from beetles a few other insect groups are represented. the vascular plants which are studied by the author represent a mixture of boreal and arctic species. the main emphasis has been o n macrofossils, of which the largest are tree trunks. up to 18 cm in diameter. but usually less than 12 cm. tree growth has bccn proved for larix, piren and betula. most trees were of stunted growth form. trec rings are extremely narrow with a mean of c. 1/4mm. this is comparable to rings from the modern arctic tree line. although this is situated much further to the south. in a light regime very different from that at kap kebenhavn below follow a few brief comments o n some of the plant remains, mostly based on the 1986 collections l a r k (larch) was the most common tree spccies. the larch remains belong to an undescribed. extinct species which resembles the extant l a r k occidenrolis from western north america, and the extinct species l . o m o l o i c a , described from the neogene of siberia, also tentalively reported from arctic canada. pirea mariana (hlaek spruce) is represented by cones and needles (fig. 1). black spruce is presently widely distributed in the boreal forests of north america, where it is dominant in poorly drained soils, especially on permafrost. i t is unknown from neogene floras of canada. the 1986 collections also comprise cones and seeds of thuja o c r i d e n f a h (arborvitae). this species is sensitive to cold winters and dry summers. at present it grows in eastern north america where it scarcely reaches the arctic tree line. a single myrira fruit had retained a few resin dots (fig. 1). the myrira fruits show resemblance to the modern m . gale (sweet gale) and the extinct m . eogole from the neogene of siberia. the winglike bracts are longer than in the modern species. hut probably shorter than in the extinct species (nikitin 1976). fruits and seeds of different herbs are also common, as exemplified by scirpus (bulrush, fig. 1) which grows in wet soil and viola (violet. fig. 1). t o / y p e / / a (fig. 1, characeae (stonewort)) is a small water plant which grows in alkaline or brackish water. water plants are usually considered to be good palaeoclimatic indicators, because they disperse rapidly and are independent of soil maturation. however, most are widely distributed. and no arctic species have evolved. the kap kebenhavn formation contains some of the oldest records of arctic plants. dryas o r f o p e t a l a leaves are amongst the most common plant remains. while the flora shows an overall phvtogeographic affinity to north america, this species does not grow i n central north america today. following the 1983 expedition we arrived at a picture of forest-tundra vegetation bordering a seasonally open sea at kap kebenhavn about 2 million years ago. the 1986 fieldwork and collections have confirmed this picture, but the taxa list is steadily increasing and the picture is now much more detailed. references abrahamsen. n. & marcussen, c. 1986: magnetostratigraphy of the plio-pleistocene kap kebenhavn formation, eastern north greenland. p h y s . earth planet. inter. 44. 5 s 6 1 . feyling-hanssen. r. w. 1986: grznsen mellem tertizr og kvartzr i nordseen og i arktis, fastlagt og korreleret ved hjelp af benthoniske foraminiferer. damk geol. foren., arsskrift for 1985. 1%33. fcyling-hanssen, r . w. 1987: the biostratigraphic position of the kap kabenhavn formation based upon its foraminifera. polur research 5 n.s. (this volume). funder. s. & hjort, c. 1980: a reconnaissance of the quat ernary geology of eastern north greenland. r a p p . gr@,ilands g e o l . u n d e r s . 99, 9%105. funder, s . , abrahamsen, n., bennike, 0. & feyling-hanssen, r. w. 1985: forested arctic: evidence from north greenland. g e o l o g y 1 3 . 542-546. funder. s . , bennike, o., mogensen, g . s . , noe-nyegaard, b . , pedersen, s . a. s . & petersen, k. s. 1984: the kap k ~ b e n h a v n formation, a late cainozoic sedimentary sequence in north greenland. r a p p . grmnlands p o l . unders. 120. 9-18. niliitin. v . p. 1976: flora mamotovoj gory po semenam i plodam. pp. 131-194 in saks, v. n. (ed.): miocen m a m o n toooj gory. izd. nauka, moskva. sund.indd 115sund 2006: polar research 25(2), 115–122 a surge of skobreen, svalbard monica sund surging glaciers are common in svalbard yet relatively few glaciers have been observed during a surge. this paper presents observations of the currently surging glacier skobreen, in southern spitsbergen. the study is based on examinations of new and archival photographs and maps. skobreen, an 18 km2 valley glacier terminating into the lower part of the glacier paulabreen, has not been registered previously as a surging glacier. skobreen experienced a build-up in its upper part, while there has been a lowering of the surface in the terminal region. photographs from 1990 show incipient crevassing in the upper part. photographs from 2003 show a slight advance of the terminus and marginal crevassing, indicating an initiation period of about 15 years for a surge of this glacier. in june 2005 transverse crevassing appeared in the upper part of the glacier, while the middle section moved as a block with strong shear margins and a pronounced drawdown of the ice surface. no traces of a surge front could be seen in the crevasse pattern. however, the crevasse pattern indicates an initiation area in the transition zone between the transverse crevassing in the upper part and the block of ice in the middle region. m. sund, svalbard science forum, box 506, no-9171 longyearbyen, norway; sund.monica@gmail.com. glacier surges are characterized by cyclical advances related to internal changes in the glacier system rather than to climate change (meier & post 1969). the cause of these instabilities is still debated. thermal trigger mechanism have been proposed (e.g. schytt 1969; clarke 1976), and changes in the subglacial drainage system are also thought to be important to the triggering of surges (clarke et al. 1984; kamb et al. 1985). the trigger mechanism has yet to be identifi ed adequately but identifying the trigger zone will contribute to our understanding of the elements involved in a surge (lawson 1996). surge-type glaciers represent only a small percentage of all glaciers and the phenomenon is highly concentrated in some glaciated regions (raymond 1987). surges constitute a common form of glacier advance in svalbard (liestøl 1969). from 13 % (jiskoot et al. 1998) up to 90 % (liestøl 1988; lefauconnier & hagen 1991) of the glaciers here are assumed to be surge-type. nevertheless, relatively few glaciers have been observed during the active surge phase (rol stad et al. 1997). the identifi cation of surge activity is essential in the study of the duration of the active and quiescent phases of surging glaciers (dowdeswell et al. 1995). the initiation of a surge is normally seen as surface crevassing of the glacier in areas where crevasses have not been present earlier and/or by an advancing glacier tongue (hagen et al. 1993). crevasses are easily mapped on glaciers, for example, from aerial photographs. they are fundamentally important to the understanding and interpretation of glacier fl ow (meier 1958; whillans et al. 1993). crevasses form in a perpendicular direction to the principal extending strain rate if the strain rate exceeds a threshold value (nye 1952; meier et al. 1974). valuable information can be acquired from observations of the crevassing in an early stage of a surge. later during the surge, the initial crevasse pattern will become 116 a surge of skobreen, svalbard more obscured. the location on the glacier at which the surge motion is initiated is one of the basic spatial properties of a surge. determination of this location is based on an understanding of the relationship between surge behaviour and crevassing (hodgkins & dowdeswell 1994; lawson 1997). the objective of this paper is to document skobreen’s ongoing surge. photographs of skobreen during a surge—at a stage which makes it possible to interpret its surge dynamics—are presented. an additional objective is to pinpoint an initiation area through the crevasse pattern and to describe the recent build-up phase using various available sources. skobreen located at 77° 42' n, 17° 03' e, skobreen is a 8.2 km long valley glacier with a drainage basin of 18.2 km2 (hagen et al. 1993) in heer land in southern spitsbergen (fig. 1). the glacier fl ows north-eastward, towards the lower part of the glacier paulabreen, a 16 km long surge-type tidewater glacier (hagen et al. 1993) feeding into the bay rindersbukta at the head of van mijenfjorden. the upper part of skobreen can be divided into one main basin, followed by three subbasins along the south-eastern side. the elevation ranges from approximately 200 to 800 m a.s.l., and the ela is estimated at 400 m a.s.l. (simões 1990). mountains from 500 to 890 m a.s.l. surround the glacier, which overlies approximately horizontal tertiary and cretaceous sedimentary rocks (salvigsen et al. 1989). skobreen was surveyed by radio-echo sounding (res) in 1985 and 1986 by a team from the scott polar research institute (drewry 1985, 1987). a rock sill was found near the glacier terminus (drewry 1987) and the mean ice thickness of the glacier was determined to be 135 m (simões 1990). most svalbard glaciers are classifi ed as polythermal (schytt 1969; liestøl 1988) and skobreen has been assumed to have a polythermal regime (drewry 1985; simões 1990). skobreen has not previously been registered as a surge-type glacier (simões 1990; hagen et al. 1993). however, the glacier was found to be extremely sensitive to small variations in air temperature. simões (1990) concluded, based on this and the res, that the possibility of surge behaviour, with a long quiescent phase, could not be ruled out. the moraine in front of the snout of skobreen is classifi ed as a lateral moraine of paulabreen that has been pushed by skobreen some fig. 1. the location of skobreen. (a) marks the development of new crevasses in the bergs chrund area; (b) marks the site marginal crevasses; (c) indicates the location of transverse crevasses; (d) is the site of a slight bulge in 2003; and (e) is the possible initiation area of the surge. paulabreen terminates in rindersbukta, van mijenfjorden. svalbard 117sund 2006: polar research 25(2), 115–122 time in the past, and not as a terminal moraine of skobreen (simões 1990). data sources and methods two sets of oblique aerial photographs covering the entire skobreen were obtained during commercial fl ights on 14 june 2005 and 20 july 2005. a digital camera with 4 megapixel resolution was used. the photographs were taken from an altitude of approximately 1500 2000 m a.s.l. slide photographs taken during a fl ight on 9 september 2003 have also been examined—these images cover only the terminus of skobreen and paulabreen on account of fog. m. jochmann from store norske spitsbergen kullkompani (snsk) provided a photograph from 25 august 2003. the norwegian polar institute’s (npi) archive of vertical aerial photographs from various years was also studied (some photographs only cover part of the glacier). the contrast in the snow in the 1970 images is very good and is also rather good in the 1990 photographs. all photographs are listed in table 1. it is also worth mentioning that a camera set up by the university centre in svalbard, in cooperation with snsk, documented an advance (not “surge”, as stated on the website at www. unis.no/research/geology/projects.htm) of paulabreen’s front from 21 april to 15 august 2005. the npi’s 1 : 100 000 topographic map c10 braganzavågen (npi 1983), on which skobreen appears, is based on a photogrammetric compilation of oblique aerial photographs from 1936 (and 1938). a new unpublished map made on the basis of 1990 aerial photographs was also obtained. longitudinal profi les of the glacier centreline were drawn on the two maps (figs. 1, 2). the quality of the older maps based on the oblique aerial photographs is dependent on the object’s distance from the camera. in this case, skobreen is rather close and the typical error in height is ± 2.5 m, while the horizontal error is 20 m (t. eiken, pers. comm. september 2005). comparison of the contour lines on bedrock on the 1936 and 1990 maps indicates that the error in the old map is no more than 10 m. results quiescent phase a notable feature of the skobreen–paulabreen interaction is the rather stable position of the terminus and moraine in front of skobreen during the studied period, 1936–1990. the moraine is more pronounced in the 1990 photographs, indicating a slight lowering of the glacier terminus. several supraglacial channels on skobreen are visible on the various aerial photographs of the glacier: three main channels draining from the upper part and two channels that cross the moraine to paulabreen. the location of these channels is very much the same in the different years, indicating stable conditions. the stable termini of skobreen and paulabreen, together with the integrity of the meltwater channels, suggest little activity in the lower parts of both glaciers prior to the present surge. the stable termini of skobreen and paulabreen, together with the semicircular shape of the skobreen moraine and the integrity of the meltwater channels, suggest low velocities and little activity table 1. photographs used in this study. year date source angle or scale number remarks 1936 – npi oblique s36 2340 2344 3000 3500 m a.s.l. 1956 – npi oblique s56 0536 0539 covers only the lower part 1961 15 aug npi 1 : 40 000 s61 2995 2996 covers only the upper part 1970 23 25 aug npi 1 : 17 000 s70 4617 4618 1977 16 aug npi 1 : 20 000 s77 0892 covers only a part 1990 25 aug npi 1 : 50 000 s90 6826 6827 2003 25 aug m. jochmann covers only the terminus 2003 9 sep m. sund covers only the terminus 2005 14 jun m. sund 2005 20 jul m. sund 118 a surge of skobreen, svalbard in lower parts of both glaciers prior to the present surge. it is not clear when paulabreen’s last surge took place, but several previous surges of the paulabreen system (including the tributary glaciers) have been described (e.g. hald et al. 2001). in 1898 the terminus of the paulabreen system stood near the outlet of rindesbukta (murray et al. 1998). photographs from 1936 show that a few decades later the terminus had retreated some 4 km, and it continued to retreat until very recently. in total this retreat measures about 14.5 km. this rapid retreat could indicate that the glacier system surged not too long before 1898. an interval of 30 (lefauconnier & hagen 1991) to 500 years (dowdes well et al. 1991) has been suggested as the duration period of the quiescent phase for svalbard glaciers, depending in part on the rate of snow accumulation (dowdes well et al. 1995). as no indications of a previous surge have been found during the last century (simões 1990; hagen et al. 1993) there is reason to believe that the skobreen has a build-up phase of 100 years or more. the longitudinal profi les of skobreen from 1936 and 1990 (fig. 2) show a decreasing ice thickness below 380 m a.s.l. above this, there has been a build-up during the same period. data (not shown) from the uppermost part are more uncertain as the glacier ends in a steep hillside. the average change in thickness above 350 m a.s.l. is about 24 m. given the area of the glacier above this elevation (6.34 km2), this implies a buildup of about 0.155 km3 of ice in the upper part of the glacier. simões (1990) found that the mean annual accumulation rate during the years 1967– 1986 was 0.33 m a–1 water equivalent. the difference between the profi les illustrates a typical pattern of a svalbard surge-type glacier during a build-up phase. the 1936 profi le reveals the combination of a convex feature in the lower part at 350 m a.s.l. followed by a fl at surface 2.5 km up the glacier to 400 m a.s.l. another bulge is found at the 450 m level. initiation generally, the 1936, 1961 and 1970 photographs show very little crevassing. there are only a very few bergschrunds in the upper areas. from 1970 to 1990 there is a difference in the crevasse pattern, but only a few of the crevasses can be attributed to variations in the snow cover. the major areas of crevassing are distinct in the 1990 photographs and totally absent in the 1970 photographs, indicating that they are new. the development of additional crevasses in the bergschrund area fig. 2. longitudinal surface profi les drawn from the 1936 and 1990 maps. bedrock is drawn after drewry (1985, 1987). 119sund 2006: polar research 25(2), 115–122 (marked a on fig. 1) and small incipient marginal crevassing (b) approximately 2 km from the head along the western margin and in the eastern margin in the main basin, as well as the development of transverse crevassing (c) in the two uppermost sub-basins, can be seen. this is best observed by comparison with the 1970 photographs. the presence of these marginal crevasses is probably the fi rst sign of the glacier decoupling from the bedrock. the incipient crevassing of the sub-basins (c) in 1990 support these indications. a slight advance of the moraine in front of skobreen can be seen on the 9 september 2003 photographs in comparison to the 1990 photographs. the 25 august 2003 photograph confi rms this advance, showing traces of marginal shear against the mountain walls in the lower part of the glacier. however, there are no visible crevasses in the terminus area. from these photographs the advance is estimated to 200 to 400 m. a slight bulge (marked d on fig. 1) can also be seen. the use of paulabreen as a snowmobile track is clear evidence that the advance at this stage was still limited as no changes were reported during the 2003 or 2004 seasons. skobreen is not commonly visited or particularly noticeable when passing by via paulabreen and changes of skobreen’s upper reaches would not necessarily be observed. surge phase the fi rst recent glaciological change noted in the rindersbukta area was the advancing glacier front of paulabreen, observed by a tourist guide in march 2005 (hanne c. christiansen, pers. comm. june 2005). independently, observations were made and photographs were taken during a fl ight to svalbard on 14 june 2005 (fig. 3a), revealing that the advancing front of paulabreen originated from the progressing terminus of skobreen and that there was extensive crevassing along this glacier. these signs indicate an active surge (liestøl 1969; meier & post 1969). no crevasses could be seen on paulabreen further up from the skobreen–paulabreen interaction. transverse crevasses on skobreen can be seen from the upper area and down to the middle section, partly appearing as huge chasms as the ice from the basins fl ows into the main ice body in area e (fig. 1). the middle section has a rather even surface, quite undisturbed by crevassing at this stage. the fi rst set of photographs was taken at the beginning of the melt season; crevasses in this area could therefore have been hidden under the snow cover. however, the second set of pictures (fig. 3b), taken more than a month later, still does not reveal crevassing of the same magnitude as further up or down this section. the western side of the glacier has no basins and shows a pronounced draw down of the ice. from the photographs, the general lowering of the surface at this stage is estimated to be 40 50 m. approximately 6.5 km from the head of the glacier, on the eastern side, a pronounced shear margin is found where debris is squeezed up along the mountainside. all the differential movement occurs in a narrow zone at the glacier margins. the presence of a sharp debris-laden shear margin indicates that a uniform block fl ow has occurred across glacier. further downwards of the block the crevassing again intensifi es, partly also into a more mixed pattern, as the tongue curves 90º around the mountain ridge sokken and drains further down and west into paulabreen. the shear margin is also visible at the confl uence with paulabreen. however, the moraine in front of skobreen is pushed forward almost undisturbed (fig. 3c). discussion the bulges in the 1936 profi le could be a part of the build-up pattern of skobreen during its quiescent phase. on hessbreen, 55 km west–southwest of skobreen, there were indications of a build-up as a result of smaller bulges propagating slowly down the glacier (sund & eiken 2004). the initiation of surges in svalbard can be a slow process developing through several years (murray et al. 1998; murray et al. 2003; sund & eiken 2004) and is often followed by a longer surge period (dowdeswell et al. 1991; murray et al. 2003), unlike glaciers with a faster initiation, for example, in alaska (harrison et al. 1994; lawson 1997). hessbreen’s surge showed that even when crevasses began to open in the upper area of the glacier, the tongue remained unaffected (sund & eiken 2004). much the same progress is found at skobreen. this suggests that the initiation phase of this surge of skobreen lasted for about 15 years. for several glaciers the active phase of the surge cycle has been characterized by a surge front propagating down glacier (e.g. echelmeyer et al. 1987; clarke & blake 1991; lawson 1997; murray et al. 1998). from the 1990 profi le, no 120 a surge of skobreen, svalbard fig. 3. the effects of the surge of skobreen. (a) view of skobreen toward the north-east, photograph taken on 14 june 2005. notice the draw down along most of the glacier. (b) view of skobreen toward the north-east; picture taken on 20 july 2005. (c) the terminus of paulabreen and skobreen; view is toward the south-east, photograph taken on 20 july 2005. (a) (b) (c) 121sund 2006: polar research 25(2), 115–122 surge front or bulge could be identifi ed. surge fronts developing in the accumulation area and propagating down glacier leave a chaotic crevasse pattern in both longitudinal and transversal directions, due to compressing and extending forces (clarke & blake 1991; lawson 1996). the appearance of transverse crevasses indicates there is no propagation of a surge front (lawson 1996; murray et al. 2003). the shear zone observed during the surge of skobreen indicates a predominant contribution of basal sliding to surge motion (echelmeyer et al. 1987). this feature is also found in a number of other actively surging glaciers in svalbard (pillewizer 1939; meier & post 1969; rolstad et al. 1997; sund & eiken 2004). the presence of transversal crevasses followed by a shear zone and block fl ow down glacier implies there no evidence of a propagating surge front on skobreen. the slight bulge feature (marked d on fig. 1) found in skobreen is likely to have been formed by the progressing block of ice decelerating and aggregating on to slower ice at the terminus of skobreen and paulabreen. thus, formation is a result of the steadily proceeding mass of activated ice, which is different to a surge front propagating down glacier having a causal relationship to the origin of the surge. on variegated glacier, in alaska, transverse crevassing was found further up from where the surge was believed have been initiated (lawson 1996). hessbreen experienced heavy transverse crevassing in its upper part followed by a block movement further down glacier. the surge was probably initiated in the upper region of this block (sund & eiken 2004). if the behaviour of skobreen is consistent with the results from variegated glacier and hessbreen, the surge of skobreen was initiated around the location marked e on fig. 1. summary from 1936 to 1990, skobreen experienced a buildup in the upper part, while there has been a reduction of ice thickness in the lower area. the 1936 profi le shows bulges which could be a part of the build-up pattern of the glacier. the smooth 1990 profi le has no indication of such bulges. the quiescent phase is assumed to have lasted for more than 100 years. comparisons of the 1970 and 1990 vertical aerial photographs reveal incipient crevassing in the upper area in 1990, probably consistent with the initiation phase of a surge. photographs from 2003 show a slightly advancing moraine and marginal crevassing in the lower part of the glacier. observations during the summer of 2005 showed that skobreen, not previously registered as a surge-type glacier (hagen et al. 1993), was actively surging. there were large crevasses in the upper part followed by a block of ice with strong shear margins advancing into and pushing the terminal part of paulabreen. the surge is therefore categorized as a block surge (pillewizer 1939). the transition between the crevassed upper part and the lower block is proposed to be the initiation area. acknowledgements.—thanks to the sas–braathens pilots who contributed to the best possible position for photographing the glacier on the fl ight from svalbard to mainland norway on 20 july 2005. thanks to an anonymous reviewer and m. bennett for constructive comments and to c. rolstad for comments on an earlier draft of the manuscript. discussions and help with fi gures from t. eiken were very much appreciated. one of the photographs was kindly provided by m. jochmann. references clarke, g. k. c. 1976: thermal regulation of glacier surging. j. glaciol. 16, 231–250. clarke, g. k. c. & blake, e. w. 1991: geometric and thermal evolution of a surge-type glacier in its quiescent state: trapridge glacier, yukon territory, canada, 1969–89. j. glaciol. 37, 158–169. clarke, g. k. c., collins s. g. & thompson, d. e. 1984: flow, thermal structure and subglacial conditions of a surge-type glacier. can. j. earth sci. 21, 232–240. dowdeswell, j. a., hamilton, g. s. & hagen, j. o. 1991: the duration of the active phase on surge-type glaciers: contrasts between svalbard and other region. j. glaciol. 37, 388–400. dowdeswell, j. a., unwin, b., nuttall, a.-m., hagen, j. o. & hamilton, g. s. 1995: mass balance change as a control on the frequency and occurence of glacier surges in svalbard, norwegian high arctic. geophys. res. lett. 22, 2909–2912. drewry, d. j. 1985: ice thickness and other glacial measurements, bakaninbreen, paulabreen and skobreen, svalbard. cambridge: scott polar research institute. drewry, d. j. 1987: svalbard glacier study. final report. vols. 1 and 2. cambridge: scott polar research institute. echelmeyer, k. a., butterfi eld, r. & cuillard, d. 1987: some observations on recent surge of peters glacier, alaska. usa. j. glaciol. 33, 341–345. hagen, j. o., liestøl, o., roland, e. & jørgensen, t. 1993: 122 a surge of skobreen, svalbard glacier atlas of svalbard and jan mayen. norsk polarinstitutt meddelelser 129. oslo: norwegian polar institute. hald, m., dahlgren, t., olsen, t.–e. & lebesbye, e. 2001: late holocene palaeoceanography in van mijenfjorden, svalbard. polar res. 20, 23–35. harrison, w. d., echelmeyer, k. a., chacho, e. f., raymond, c. f. & benedict, r. j. 1994: the 1987–88 surge of west fork glacier sutsina basin, alaska, usa. j. glaciol. 40, 241–254. hodgkins, r. & dowdeswell, j. a. 1994: tectonic processes in svalbard tide-water glacier surges—evidence from structural glaciology. j. glaciol. 40, 553–560. jiskoot, h., boyle. p. & murray, t. 1998: the incidence of glacier surging in svalbard: evidence from multivariate statistics. comput. geosci. 24, 387–399. kamb, b., raymond, c. f., harrison, w. d., engelhardt, h., echelmeyer, k. a., humphrey, n., brugman, m. m. & pfeffer, t. 1985: glacier surge mechanism: 1982–1983 surge of variegated glacier, alaska. science 227, 469–479. lawson, w. 1996: structural evolution of variegated glacier. j. glaciol. 42, 261–270. lawson, w. 1997: spatial, temporal and kinematic characteristics of surges of variegated glacier, alaska. ann. glaciol. 24, 95–101. lefauconnier, b. & hagen, j. o. 1991: surging and calving glaciers in eastern svalbard. norsk polarinstitutt meddelelser 116. oslo: norwegian polar institute. liestøl, o. 1969: glacier surges in west-spitsbergen. can. j. earth sci. 6, 895–897. liestøl o. 1988: the glaciers in the kongsfjorden area, spitsbergen. nor. j. geogr. 42, 231–238. meier, m. f. 1958: the mechanics of crevasse formation. int. assoc. sci. hydrol. publ. 46, 500–508. meier, m. f., kamb, w. b., allen, c. r. & sharp, r. p. 1974: flow of blue glacier, olympic mountains, washington, usa. j. glaciol. 13, 187–212. meier, m. f. & post, a. 1969: what are glacier surges? can. j. earth sci. 6, 807–817. murray, t., dowdeswell, j. a., drewry, d. j. & frearson, i. 1998: geometric evolution and ice dynamics during a surge of bakaninbreen, svalbard. j. glaciol. 44, 263–272. murray, t., luckman, a. j., strozzi, t. & nuttall, a.-m. 2003: the initiation of glacier surging at fridtjovbreen, svalbard. ann. glaciol. 36, 110–116. npi 1983: c10 braganzavågen. oslo: norwegian polar institute. nye, j. f. 1952: the mechanics of glacier fl ow. j. glaciol. 2, 82–93. pillewizer, w. 1939: die kartographischen und gletcherkundlichen ergebnisse der deutchen spitsbergen expedition 1938. (the cartographic and glacier related results of the german spitsbergen expedition, 1938.) petermanns geographische mitteilungen, ergänzungsband 238, 36–38. raymond, c. f. 1987: how do glaciers surge? a review. j. geophys. res. 92(b9), 9121–9134. rolstad, c., amlien, j., hagen, j. o. & lundén, b. 1997: visible and near-infrared digital images for determination of ice velocities and surface elevation during a surge on osbornebreen, a tidewater glacier in svalbard. ann. glaciol. 24, 255–261. salvigsen, o., winsnes, t. s. & steel, r. 1989: geological map, svalbard 1 : 100 000. sheet c10g, braganzavågen. norsk polarinstitutt temakart 4. oslo: norwegian polar institute. schytt, v. 1969: some comments on glacier surges in eastern svalbard. can. j. earth sci. 6, 867–871. simões, j. c. 1990: environmental interpretation from svalbard ice cores. phd thesis, university of cambridge. sund, m. & eiken, t. 2004: quiescent-phase dynamics and surge history of a polythermal glacier: hessbreen, svalbard. j. glaciol. 50, 547–555. whillans, i. m., jackson, m. & tseng, y.–h. 1993: velocity pattern in a transect across ice stream b, west antarctica. j. glaciol. 39, 562–572. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <feff004f007000740069006f006e007300200070006f0075007200200063007200e900650072002000640065007300200064006f00630075006d0065006e00740073002000500044004600200064006f007400e900730020006400270075006e00650020007200e90073006f006c007500740069006f006e002000e9006c0065007600e9006500200070006f0075007200200075006e00650020007100750061006c0069007400e90020006400270069006d007000720065007300730069006f006e00200070007200e9007000720065007300730065002e0020005500740069006c006900730065007a0020004100630072006f0062006100740020006f00750020005200650061006400650072002c002000760065007200730069006f006e00200035002e00300020006f007500200075006c007400e9007200690065007500720065002c00200070006f007500720020006c006500730020006f00750076007200690072002e0020004c00270069006e0063006f00720070006f0072006100740069006f006e002000640065007300200070006f006c0069006300650073002000650073007400200072006500710075006900730065002e> /deu <feff00560065007200770065006e00640065006e0020005300690065002000640069006500730065002000450069006e007300740065006c006c0075006e00670065006e0020007a0075006d002000450072007300740065006c006c0065006e00200076006f006e0020005000440046002d0044006f006b0075006d0065006e00740065006e0020006d00690074002000650069006e006500720020006800f60068006500720065006e002000420069006c0064006100750066006c00f600730075006e0067002c00200075006d002000650069006e00650020007100750061006c00690074006100740069007600200068006f006300680077006500720074006900670065002000410075007300670061006200650020006600fc0072002000640069006500200044007200750063006b0076006f0072007300740075006600650020007a0075002000650072007a00690065006c0065006e002e00200044006900650020005000440046002d0044006f006b0075006d0065006e007400650020006b00f6006e006e0065006e0020006d006900740020004100630072006f0062006100740020006f0064006500720020006d00690074002000640065006d002000520065006100640065007200200035002e003000200075006e00640020006800f600680065007200200067006500f600660066006e00650074002000770065007200640065006e002e00200042006500690020006400690065007300650072002000450069006e007300740065006c006c0075006e00670020006900730074002000650069006e00650020005300630068007200690066007400650069006e00620065007400740075006e00670020006500720066006f0072006400650072006c006900630068002e> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice falck.indd 193falck 2001: polar research 20(2), 193–200 contribution of waters of atlantic and pacific origin in the northeast water polynya eva falck measurements of nitrate and phosphate taken in the northeast water polynya (newp) during the summer of 1993 have been used to identify the contribution of waters of atlantic and pacific origin in the polynya. since waters from the northern pacific exhibit a deficit in nitrate relative to phosphate due to denitrification in low oxygen waters, the relationship between nitrate and phosphate can be used to distinguish between oceanic waters of pacific and atlantic origin. the pacific water enters the arctic ocean through bering strait and flows along the northern coasts of alaska and canada. some of this water exits through fram strait and may therefore enter the polynya which is situated above the continental shelf off the north-eastern coast of greenland. compared to data from the greenland sea, which only show a n–p relationship of typical atlantic water, the data from the northeast water polynya show that the upper waters of the polynya bear a clear signal of waters of pacific origin. in the surface mixed layer an average of about 90 % is found to have pacific n–p characteristics. below the surface mixed layer the amount of pacific derived water decreases through the halocline and from about 150 m to the bottom only typical atlantic water is found. e. falck, dept. of analytical and marine chemistry, göteborg university, se-41296 göteborg, sweden. the northeast water polynya is a recurrent polynya situated above the continental shelf off the north-eastern coast of greenland north of 79° n (fig. 1). its formation is attributed to the combined effect of a fast ice barrier in the south, norske øer ice barrier (nøib), and a northward flowing coastal current, the northeast greenland coastal current (schneider & budéus 1995). most authors agree that the upper water of the east greenland shelf, between the coast and the east greenland polar front, is imported from the arctic ocean (e.g. bourke et al. 1987). on the other hand, budéus et al. (1997) find that several arguments oppose this suggestion and indicate that the waters found in the upper water column of the newp area are locally formed. the surface water on the east greenland shelf has a rather different nutrient regime than that found in the adjacent greenland sea. while phosphate and silicate are slightly higher, nitrate has rather low values, about 4 µm (lara et al. 1994) before the onset of the biological season compared to about 12 µm (smith et al. 1991) in the greenland sea. these differences in the relationship between nutrients are used in this work to infer the origin of the waters in the northeast water polynya, and to show that the upper water mass on the shelf bears a clear signal of pacific origin and therefore must be imported from the arctic ocean. the pacific influence can be seen in the relationship between nitrate and phosphate, where pacific-derived waters have a higher phosphate concentration relative to nitrate as compared to atlantic water (wilson & wallace 1990). this water flows into the arctic ocean through bering strait, along the northern coasts of alaska and 194 contribution of waters of atlantic and pacific origin canada and exits through the canadian archipelago and fram strait. jones et al. (1998) found that the upper 30 m of the water close to the abovementioned coasts had a proportion of pacificderived water of more than 90 %. this high percentage of pacific water is also found in the polynya area as seen with newp92 data by wallace et al. (1995a) using the nutrient ratio no/po; a similar finding is shown here with the 1993 data using a n/p relation. this work is based on hydrographic and chemical data collected between 22 july and 17 august 1993 on board the us coast guard cutter polar sea, taken between 76.5° n and 81° n and west of 5° w (fig. 1). the reader is referred to wallace et al. (1995a, 1995b) for details of the analysis procedure and the data collected. hydrography of the northeast water polynya the hydrography of the east greenland shelf has a two-layered water structure with a relatively fig. 1. map of the northeast water polynya with station positions occupied during the 1993 cruise aboard the polar sea. the dashed line separates the polynya area from the northern slope (stations from transect e and n that are east of the dashed line) and belgica trough. this line also gives the approximate limits of the distribution of the knee water as observed during this cruise. circulation pattern is shown by arrows, with light arrows indicating water of high pacific content. nøib stands for norske øer ice barrier. 195falck 2001: polar research 20(2), 193–200 cold and fresh water body above warmer and saltier waters (aagaard & coachman 1968). the water masses on the shelf have been described by bourke et al. (1987) as polar water, with temperatures less than 0 °c and salinities below 34.5, and arctic intermediate water (aiw), defined as 0 °c < t < 3 °c and 34.5 < s < 34.9. the 1993 data (wallace et al. 1995b) show that in the polynya there is a layer of near-freezing point water with a salinity of about 32.4 (fig. 2). underneath this layer is the halocline, found at depths between about 50 and 150 m, where the salinity increases to values characteristic of the aiw. during summer the polar water is warmed and diluted with runoff and/or sea ice meltwater at the surface. also illustrated in fig. 2, polar water can be subdivided into two different water masses. this was done by paquette et al. (1985), who showed the existence of a colder water type than could be obtained by linear mixing of polar and atlantic water. this water mass was named knee water after its properties in ts space. stations where the presence of knee water is evident do not show the typical near freezing point layer associated with s = 32.4 and the knee water type is not found inside the dashed line of fig. 1. therefore, in this work, the region has been divided into the polynya area west of the line, and the northern slope area and the belgica trough area east of the line. the latter subdivision is mainly done to see if there are any significant differences between the northern and southern parts of the slope. the shelf area consists of a trough system around belgica bank with belgica trough to the south of the ice barrier and norske trough between the coast and belgica bank, with westwind trough north of this bank. the troughs are about 300 500 m deep with shallower sills separating norske trough from both belgica trough and westwind trough. nøib bridges norske trough and is grounded on the central belgica bank. this bridge allows water to enter the polynya from the south except for maybe the upper 10 m (schneider & budéus 1997). the northward flowing coastal current follows the trough system northwards and turns east in westwind trough. in the northern part the eastward flow connects this current with the southward flow of the east greenland current (egc). part of the egc crosses the shelf diagonally (bourke et al. 1987; budéus & schneider 1995), and in the belgica trough the currents components are south-eastward except for a very narrow area close to île de france where the northward flow is found. topp & johnson (1997) found from year-long current meters and adcp sections opposites flows at each side of the northeast greenland coastal current along the slopes of the westwind trough. fig. 2. potential temperature versus salinity diagram where water types are identified as follows: polar water (pw), arctic intermediate water (aiw), and deep water (dw). the surface water is the seasonally heated and diluted polar water. 196 contribution of waters of atlantic and pacific origin calculation of source waters this work is based on the same method as used by jones et al. (1998) to calculate the relative amounts of atlantic and pacific source waters. the n–p relations characterizing “pure” atlantic water and “pure” pacific water are illustrated by straight lines in fig. 3 and given by the following equations for the atlantic and pacific waters respectively: no3 aw = 17.499xpo4 aw 3.072 (1) no3 pw = 14.828xpo4 pw 12.16 (2) the second equation has been slightly modified since the paper in 1998 (jones pers. comm.). the linear relationships define a value of phosphate of pure atlantic water and one for pure pacific water for each measured nitrate value. together with the measured phosphate value the relative amounts of atlantic (including freshwater) and pacific water are determined. river run-off and sea ice meltwater in the arctic ocean have a n–p relation close to the atlantic water. the first equation is derived from measurements in the st. anna trough and is characteristic of atlantic water in the arctic. the second equation is based on measurements from the chukchi sea and characterizes water from the bering sea that has been modified on the chukchi shelf. this modified bering sea water is therefore what in this work is called pacific water. due to different uncertainties, jones et al. (1998) found that the computed source water contributions should be considered somewhat approximate and likely no better than 10 %. results and discussion many stations in the newp area showed depletion of nitrate in the surface as a result of biological uptake during the summer. phosphate fig. 3. nitrate versus phosphate for (a) the polynya area, (b) the northern slope area, (c) the belgica trough, and (d) the central greenland sea. mld in (a) stands for mixed layer depth and data below this line are from the mixed layer. (a) (c) (d) (b) 197falck 2001: polar research 20(2), 193–200 fig. 4. percentage of pacific water against depth for (a) all casts in the polynya area, (b) selected casts along the trough system and belgica bank, and (c) selected casts in belgica trough together with one cast (165) from the southern tip of belgica bank. see fig. 1 for position of the selected casts. (a) (c) (b) 198 contribution of waters of atlantic and pacific origin continued to decrease after the depletion of nitrate indicating that other nitrogen sources were then used together with phosphate during photosynthesis. this gives varying values of phosphate for nitrate equal to zero in the nitrate against phosphate plots (fig. 3). apart from these points, one can see that data from the mixed layer of the polynya area (fig. 3a) lie close to the pacific water line, while data from below about 150 m lie close to the atlantic water line. the data in between are from the halocline. for the northern slope region (fig. 3b) the picture is more or less the same, although some of the data points have values closer to those from belgica trough (fig. 3c). these measurements are from the outermost stations in transects e and n over the deeper parts of the slope. in the belgica trough only traces of pacific water is present close to the surface. for comparison fig. 3d shows data from the upper 500 m of the central greenland sea (around 75° n and 0° w). here no traces of pacific water signature is found; all data lie along the line of atlantic water. the calculated distribution of pacific water with depth for all stations in the polynya area is shown in fig. 4a. except for the diluted upper surface water, the mixed layer content of pacific water has a mean value of about 90 %. fresh water from runoff, sea ice melt, and precipitation have nearly the same n–p relationship as atlantic water, which, together with the above-mentioned depletion of nitrate in some areas, explains while the diluted surface water has values varying between 20 and 100 % pacific water. the distribution is also shown for selected casts around the deep trough system in the polynya area in fig. 4b with the last cast (st129) being on belgica bank (south-western part of transect n), and for selected casts in belgica trough in fig. 4c. as can be seen in fig. 4b, a high percentage of pacific water is found all the way around belgica bank with more than 95 % in the deeper parts of the mixed layer. for the stations in belgica trough the upper 50 m has a variable pacific water content from about 90 % to 0 %. included in this figure is also the station from the southern tip of belgica bank (st165) which lies just north of the most westerly station in belgica trough (st166). st165 shows a pacific content of about 100 % down to 100 m while st166 has only about 80 % at 15 m depth and 60 % at 35 m depth. this shows that just inside the dashed line (fig. 1) high values of pacific water are found down to the base of the mixed layer, in contrast to the small amounts only found near the surface at the stations in belgica trough. it is evident that this high pacific water signature in the polynya and northern slope areas indicates an import from the arctic ocean. this signature could also be obtained if high denitrification took place locally on the east greenland shelf, but this can be ruled out since oxygen concentrations are too high for local denitrification. jones et al. (1998) found water of high pacific content along the continental shelves north of alaska and canada, but also pacific source water concentrations of greater than 90 % immediately north of greenland, which shows that some of this water indeed has to exit through fram strait. newton & sotirin (1997) show that an eastward flowing boundary current is positioned over the continental slope of the lincoln sea between the shelf break and the base of the slope. they also showed that during 1991–94 the presence of pacific water (bering sea water) in the upper halocline of the lincoln sea increased significantly. this water can be seen in the arctic ocean as a relative tmax associated with salinities of about 31.9 32.7 overlying a relative tmin associated with salinities in the range of 32.7 33.5. for both the polynya and the northern slope areas there is a maximum in both silicate and phosphate in the middle of the halocline at a salinity of about 33 to 33.5. this coincides with the core salinity of the nutrient rich water of the upper halocline water of the arctic ocean (jones & anderson 1986). the fractions of pacific and atlantic water at this salinity is about 50/50 ± 10 and is found at about 100 m in all the casts from the polynya area, but higher up in the water column, at about 50 m, over the northern slope. at the stations from the belgica trough this maximum is not seen. there is a good correlation between silicate and phosphate, but a clear difference is seen in the slope between the different areas. in the polynya and the northern slope areas the slope is about 24, while in belgica trough the slope is about 12.5, the two lines intersect at the silicate value of about 12 µm. silicate and phosphate concentrations at the bottom of the mixed layer water and at the top of the atlantic layer are more or less equal—about 11.5 µm and 1 µm, respectively. from the increase in these constituents down to the middle of the halocline it is evident that this halocline water cannot be produced on the shelf through mixing 199falck 2001: polar research 20(2), 193–200 between the surface and the atlantic water, but has to be advected into the region. the same conclusion was put forth by topp & johnson (1997) from current meter measurements of temperature and salinity, and they suggested that this distinct water mass possibly was a mixture of polar water, knee water and atlantic water. the low silicate concentrations of the knee water (about 6 µm; budéus et al. 1997), however, oppose this idea. to achieve a 50/50 mixture of pacific and atlantic waters with the higher silicate and phosphate concentrations found in the polynya halocline the only candidate is the nutrient rich upper halocline water of the arctic ocean. for instance, a 50/50 mixture between the surface mixed layer water and the upper halocline water, which is also of pacific origin, with the atlantic water below, would indeed result in silicate values similar to those found in the polynya halocline at salinities of 33.0 33.5. during 1991 to 1993 the increase in tmax of the pacific water over the lincoln sea slope was accompanied by a reduction in the thickness of the surface mixed layer from about 80 to 20 m (newton & sotirin 1997). taking into account the distance from the lincoln sea area and the approximate time it takes for this water to flow into the polynya area one can compare the measurements from the polynya with those from the lincoln sea. surface currents are weak in the lincoln sea, about 1-2 cm s-1 over the shelf. this indicates a passage time of about two years. the 1991 profiles in the lincoln sea show a wellmixed surface layer (polar mixed layer) down to about 75 m with t at the freezing point and salinity close to 32.4. in the following years the mixed layer decreased and freshened, giving lower freezing temperatures. the increasing tmax just below the mld also got shallower, with the highest (and shallowest) tmax in 1993. the boundary current over the slope was faster (about 4 cm s-1) and with this speed the water would reach the the northeastern shelf of greenland in a little less then one year. this can explain the shallow signal of the upper halocline water seen at stations from the northern slope compared to the deeper position of the halocline inside the polynya area. the water of atlantic origin can be seen in fig. 4 as water of about 0 % and is found below the halocline. negative values, as those seen in fig. 4c, are typical of return atlantic water, i.e. water that flows north with the west spitsbergen current but does not enter the arctic ocean. instead it recirculates just south of fram strait, emerging under the polar water and following the egc southwards. this water can be seen at depths between 100 and 500 m with a core at about 300 350 m in the belgica trough. at the depth of the knee water temperature minimum, e.g. eastern part of transect e, where the temperature minimum is -1.8 at 100 m depth, the amount of pacific water is close to 0 %, indicating an atlantic origin of the knee water. in accordance with budéus & schneider (1995) and budéus et al (1997), it is shown here that the part of the east greenland current that contains knee water does not enter the newp. conclusions these results show that waters of both pacific and atlantic origin are present above the east greenland shelf. since the distribution of source waters must reflect the circulation pattern of the region, the following sheme is visualized: pacific-derived surface water from the chukchi sea follows the northern coasts of alaska, canada and greenland and enters the newp area through fram strait as an inner branch of the east greenland current. due to the northward flowing coastal current along the trough system, which seems to be a persistent feature of the circulation pattern in the polynya, the imported surface water probably passes over ob bank and flows south close to the coast of greenland and/or circulates south of the belgica bank before it turns northward following the current in the polynya. the outer part of the egc containing the knee water must be drawn from a more easterly part of the arctic ocean, and when the egc crosses the shelf diagonally south of belgica bank, the inner branch is caught up in the northward flowing coastal current while the outer part continues southward. several indices support this sheme, as discussed above. the water mass structure in the northeast water polynya is two-layered, with a surface layer consisting of pacific-derived water, as found on the chukchi shelf down to the mixed layer depth, and atlantic water below the halocline. in the middle of the halocline, where the mixture of the two water masses is about 50/50, the signal of the upper halocline water from the arctic ocean is seen as a maximum in silicate and phosphate at a salinity of about 33.1. the slope region of the northern newp area shows the same trend 200 contribution of waters of atlantic and pacific origin as the polynya data, although the upper halocline water is present at shallower depths. the measurements from the belgica trough, south of the polynya, only show small fractions of pacific water as this water derives from a more easterly part of the egc. the knee water, which is present only outside the polynya area, has a clear atlantic origin. acknowledgements.—the author is very much indebted to douglas wallace for many fruitful discussions on the northeast water polynya and for the opportunity to use the 1993 data in this work. also special thanks to leif anderson who gave me the idea for this work and has been of great help in the writing of the manuscript. the paper was written with financial support from the swedish natural science research council. references aagaard, k. & coachman, l. k. 1968: the east greenland current north of denmark strait: part ii. arctic 21, 267–290. bourke, r. h., newton, j. l., paquette, r. g. & tunnicliffe, m. d. 1987: circulation and water masses of the east greenland shelf. j. geophys. res. 92(c7), 6729–6740. budéus, g. & schneider, w. 1995: on the hydrography of the northeast water polynya. j. geophys. res. 100(c3), 4287–4299. budéus, g., schneider, w. & kattner, g. 1997: distribution and exchange of water masses in the northeast water polynya (greenland sea). j. mar. syst. 10, 123–138. jones, e. p. & anderson, l. g. 1986: on the origin of the chemical properties of the arctic ocean halocline. j. geophys. res. 91(c9), 10759–10767. jones, e. p., anderson, l. g. & swift, j. h. 1998: distribution of atlantic and pacific waters in the upper arctic ocean: implications for circulation. geophys. res. lett. 25, 765–768. lara, r. j., kattner, g., tillmann, u. & hirche, h.-j. 1994: the northeast water polynya (greenland sea) ii. mechanisms of nutrient supply and influence on phytoplankton distribution. polar biol. 14, 483–490. newton, j. l. & sotirin, b. j. 1997: boundary undercurrent and water mass changes in the lincoln sea. j. geophys. res. 102(c2), 3393–3403. paquette, r. g., bourke, r. h., newton, j. f. & perdue, w. f. 1985: the east greenland polar front in autumn. j. geophys. res. 90(c3), 4866–4882. schneider, w. & budéus g. 1995: on the generation of the northeast water polynya. j. geophys. res. 100(c3), 4269–4286. schneider, w. & budéus g. 1997: a note on norske ø ice barrier (northeast greenland), viewed by landsat 5 tm. j. mar. syst. 10, 99–106. smith, w. o., jr., codispoti, l. a., nelson, d. m., manley, t., buskey, e. j., niebauer, h. j. & cota, g. f. 1991: importance of phaeocystis blooms in the high-latitude ocean carbon cycle. nature 352, 514–516. topp, r. & johnson, m. 1997: winter intensification and water mass evolution from year long current meters in the northeast water polynya. j. mar. syst. 10, 157–173. wallace, d. w. r., minnett, p. j. & hopkins, t. s. 1995a: nutrients, oxygen, and inferred new production in the northeast water polynya, 1992. j. geophys. res. 100(c3), 4323–4340. wallace, d. w. r., hopkins, t. s., behrens, w. j., bignami, f., deming, j., kinder, c., shi, y., smith, w. o., top, z. & walsh, i. d. 1995b: collaborative research on the northeast water polynya: newp93. hydrographic data report, uscgc polar sea cruise, july 18–august 20, 1993. upton, ny: brookhaven national laboratory. wilson, c. & wallace, d. w. r. 1990: using the nutrient ratio no/po as a tracer of continental shelf waters in the central arctic ocean. j. geophys. res. 95(c12), 22193–22208. østerhus.indd 169østerhus et al. 2001: polar research 20(1), 169–175 observed transport estimates between the north atlantic and the arctic mediterranean in the iceland–scotland region svein østerhus, william r. turrell, bogi hansen, peter lundberg & erik buch the arctic mediterranean is the ocean area north of the greenland–scotland ridge. exchanges between this region and the north atlantic both provide the main source for production of north atlantic deep water and supply heat and salt to the northern oceans. the exchange occurs through several gaps in the ridge; in terms of volume flux the iceland–scotland gap is the most important one as it carries more than half the total, with approximately three quarters of the total inflow and one third of the total outflow. the nordic woce observational system was initiated to monitor the exchanges through this gap and it has provided data that allow estimates of typical fluxes and their seasonal variation. the flux measurements show that most of the atlantic inflow to the arctic mediterranean returns as overflow and hence the processes forming intermediate and deep waters in the arctic mediterranean are the main forcing mechanism for the atlantic inflow. the inflow between iceland and scotland seems to be a maximum in late winter while the faroe bank channel overflow is strongest in late summer. using the results from the nordic woce system it has been possible to interpret historical observations from ocean weather ship station m and conclude that the flux of the faroe bank channel overflow decreased in magnitude from 1950 to 2000. s. østerhus, bjerknes centre for climate research and geophysical institute, university of bergen, allégaten 70, n-5007, bergen, norway; w. r. turrell, marine laboratory, victoria road 90, aberdeen ab11 9db, uk; b. hansen, faroese fisheries laboratory, box 3051, fo-110 torshavn, faroe islands; p. lundberg, meteorological institute, university of stockholm, sweden; e. buch, danish meteorological institute, lyngbyvej 100, dk-2100 copenhagen, denmark. the arctic mediterranean consists of the arctic ocean and the nordic seas (the norwegian sea, the iceland sea and the greenland sea). in this region, cooling and brine rejection increase the density of upper layer waters sufficiently so that they may descend to intermediate (500 1000 m) or deep levels. these “ventilated” waters leave the arctic mediterranean as deep “overflow” across the greenland–scotland ridge into the north atlantic (fig. 1), and together with ambient water entrained en-route, they become the main source of north atlantic deep water, nadw (dickson & brown 1994). to balance the overflow and the surface outflows through the denmark strait and through the canadian archipelago, a large inflow is needed and most of it derives from the north atlantic. this inflow of warm, saline atlantic water is generally considered to be the main reason for the relatively mild climate of large parts of the arctic mediterranean as well 170 observed transport estimates between the north atlantic and the arctic mediterranean as much of northern europe (rahmstorf & ganopolski 1999). it is also a mechanism for transporting salt, and hence density, to the ventilation areas. the exchanges of water, heat and salt between the north atlantic and the arctic mediterranean are therefore critical for maintaining the presentday global thermohaline circulation as well as the climatic conditions in the region. this has been the motivation for establishing the observational system discussed in this paper. it was initiated as part of the nordic world ocean circulation experiment (woce) project, which also included observations in the denmark strait; here we discuss only the observations in the iceland–scotland region. monitoring the fluxes of atlantic water entering the arctic mediterranean between iceland and scotland and of the overflow through the faroe bank channel, the system has been in operation from 1994 up to the present, with funding from various sources. in this overview paper, we describe the nordic woce system, list the main data sets acquired, and review some of the main results. the observational system the nordic woce system is based on a combination of regular ctd standard sections and quasipermanent adcp moorings along or close to the section lines (fig. 2). these sections cross the two main inflow branches as well as the overflow through the faroe bank channel (fig. 1). the ctd observations on the standard section in the faroe–shetland channel (section s on fig. 2) are the continuation of a long-term series of regular classical hydrographic observations that started in the beginning of the 20th century. this section is now occupied four to seven times a year with scottish and faroese research vessels. the other two sections (w and n on fig. 2) were initiated in the late 1980s and are occupied four times a year by a faroese research vessel. the adcp moorings started operation in 1994 and are now continuous except for about three weeks of servicing once a year. each mooring has one upward-looking adcp (acoustic doppler current profiler) which every 20 minutes measures a velocity profile in 20 25 separate layers that cover most of the water column above the instrument. most of the adcps are 75 khz instruments, manufactured by rdi, mounted at the top of single point moorings with the adcp at 600 840 m depth. three of the standard sites are sufficiently shallow, however, that 150 khz instruments could be used, but they require special protection from fisheries. at site se (fig. 2) the mooring has been located in protected areas associated with offshore oil exploration, but at fig. 1. the greenland–scotland ridge (light brown areas are shallower than 500 m) separates the nordic seas from the atlantic. continuous arrows indicate exchanges monitored by the nordic woce system. broken arrows indicate other exchanges. numbers indicate typical fluxes of water in sv (1 sv = 106 m3⋅s-1), heat in tw (1 tw = 1012 w), and salt in kilotonnes per second. thick black lines indicate sections monitored by the observational system. fbc denotes the faroe bank channel, and wtr the wyville-thomson ridge. 171østerhus et al. 2001: polar research 20(1), 169–175 sites na and sa, special trawl-protecting frames had to be developed. data sets the hydrographic data set includes observations of temperature and salinity from more than 150 cruises at section s (fig. 2) dating back to 1903, and more than 50 cruises at sections n, and w dating back to 1988. at section s, the data were acquired by nansen bottle casts at standard depths until 1994, after which time ctds have been used. at the other two sections, ctds have been used throughout the period. various instruments and acquisition and calibration procedures have been in use and the data quality is variable. for flux calculations of the various water masses, we have used only the modern data where the quality is well beyond the requirements. at the beginning of the observational period, instrumental problems with the adcps reduced data coverage considerably. after these were resolved there have also been occasional instrument failures in addition to problems arising from fisheries or mooring equipment. the data coverage (fig. 3) is therefore not continuous; but exchange of data with the offshore industry has enhanced the coverage over the scottish slope considerably. flux estimates the gaps in data coverage complicate the simultaneous evaluation of fluxes of various branches. we therefore expect estimates to be refined as the measurements continue. nevertheless, it appears that the data already acquired allow consistent flux values to be evaluated for the iceland–scotland inflow of atlantic water and for the faroe bank channel overflow. the inflow of atlantic water to the arctic mediterranean is carried by three separate branches and the nordic woce system monitors the two dominant ones. a section crossing both of these flows (sections n and s on fig. 2 combined) shows the atlantic water, characterized by high salinities, focused over the two slope regions north of the faroes and west of shetland, respectively, while there is a weaker return flow on the faroese side of the faroe–shetland channel (fig. 4). from the measurements, we have estimated the average flux of atlantic water to be 3.3 sv (106 m3⋅s-1) between iceland and the faroes (hansen et al. 1999) and 3.7 sv between the faroes and shetland (turrell et al. 1999). the heat and salt fluxes of these two branches have also been estimated (fig. 1). the faroe bank channel is the deepest passage across the greenland–scotland ridge and is the main outlet for the coldest deep water produced in the arctic mediterranean. the deepest fig. 2. the observational system covers the two main atlantic inflow branches and the faroe bank channel overflow with ctd sections (black lines) and adcp moorings (orange circles and rectangles), identified by two-letter labels. in addition to the standard mooring sites shown, there have been a few short-term deployments at other sites. fig. 3. periods with good adcp data until mid-summer 2000 at each of the standard mooring sites (fig. 2). at sites sd, and se, measurements made available by the offshore industry are included. 172 observed transport estimates between the north atlantic and the arctic mediterranean parts of the channel are constantly filled with cold overflow water which flows into the atlantic with average velocities exceeding 1 m⋅s-1 in the core (fig. 5). the 3 °c isotherm is often defined as the upper boundary of iceland–scotland overflow water (isow) but this definition includes some entrained atlantic water. water colder than +0.5 °c is a purer form of ventilated water (hansen & østerhus 2000), consisting of norwegian sea deep water (nsdw; < -0.5 °c) and norwegian sea arctic intermediate water (nsaiw; -0.5 °c to +0.5 °c). the adcp moored at the sill of the channel (site fb in fig. 2) has measured almost continuously since november 1995 (until june 2001, so far). combining these measurements with the results from a 70 day experiment with three moored adcps (fig. 5), the flux of water colder than +0.5 °c (nsdw + nsaiw) was estimated to be 1.5 sv (106 m3⋅s-1) and that of isow as 1.9 sv (østerhus et al. 1999). combining the flux estimates of atlantic inflow and faroe bank channel overflow from the nordic woce system with estimates made by others in other areas, a consistent water balance for the arctic mediterranean may be established (fig. 6). in addition to the two atlantic inflow branches monitored by the nordic woce system, there is also a branch west of iceland which transports about 1 sv of atlantic water (kristmannsson 1998). adding 1 sv of inflow through the bering strait (roach et al. 1995), the total inflow to the arctic mediterranean is about 9 sv, which has to be balanced by a similar flux out into the atlantic. the overflows carry most of this outflow. adding the faroe bank channel isow flux to estimates for the overflow across the iceland– faroe ridge (1.1 sv; hermann 1967) and across the wyville-thomson ridge (0.1 sv; ellett 1998), gives a total iceland–scotland overflow of about 3 sv, which is similar to the 3 sv generally quoted for the denmark strait overflow (dickson & brown 1994). subtracting the total overflow from the total inflow leaves a flux of about 3 sv for the outflows in the upper layers through the canadian archipelago and through the denmark strait, carried by the east greenland current. the relatively low salinity bering strait inflow probably contributes little to the overflow, so fig. 6 therefore implies that about three quarters of the atlantic inflow is converted to overflow. future refinements will no doubt modify these numbers, but fairly drastic modifications are needed to change the basic conclusion that most of the atlantic inflow returns as overflow. this again has implications for the forcing mechanisms of the exchanges. the thermohaline ventilation that converts atlantic water to intermediate and deep overflow waters is the process that maintains the overflow into the atlantic, and the removal of water by the overflow will tend to lower the sea level in the arctic mediterranean. the resulting sea level gradient across the ridge creates a barotropic pressure gradient that forces a compensating inflow in the surface layers. thus, a thermohaline ventilation that induces a certain overflow flux will also induce a compensating fig. 4. average salinity (colour) on sections n and s (fig. 2) and average velocity perpendicular to the sections shown by isolines with velocity in cm⋅s-1 (positive towards the east and north-east, respectively). hatched area indicates flow towards the atlantic. standard mooring sites with adcps indicated by orange circles with soundbeams illustrated as yellow cones. labels above the sections indicate every second standard station. 173østerhus et al. 2001: polar research 20(1), 169–175 atlantic inflow of the same magnitude. this is not the only forcing mechanism operating. estuarine forcing and forcing by wind stress are other alternatives and they may be the dominant exchange forcings for parts of the arctic mediterranean. however, for the arctic mediterranean as a whole, fig. 6 indicates that thermohaline ventilation is the main forcing mechanism. seasonal flux variations with the available data set it is possible to estimate the seasonal variation with a certain confidence. for the current flowing north of the faroes, a clear seasonal cycle is evident for the total volume flux (hansen et al. 2000) with maximum flux around march. much of this water does, however, derive from the east icelandic current and other areas in the arctic mediterranean. when we consider only the part deriving from the atlantic, the seasonal variation of the iceland–faroe inflow is much less pronounced and its amplitude does not seem to exceed 1 sv (hansen et al. 2000). in the faroe–shetland channel, the data coverage has not been as complete. nevertheless, a fairly consistent picture emerges, with little or no seasonal variation of the net inflow through this channel. our observations certainly indicate seasonal variations in the fluxes over the scottish (south-eastern) side of the channel, as others have seen (gould et al. 1985), but these variations seem to be compensated by similar variations in the outflow over the faroese (north-western) side (hansen et al. 2000). this seems to leave the iceland–scotland inflow of atlantic water with a seasonal amplitude of perhaps 1 sv in magnitude and maximum in late winter. the atlantic inflow branch, west of iceland, has a seasonal amplitude of similar magnitude, but out of phase, and the conclusion is that the total atlantic inflow to the arctic mediterranean does not have a seasonal amplitude exceeding 15 % of the mean flow (hansen et al. 2000). in the faroe bank channel, the adcp measurements show large fluctuations on time scales of days and weeks; when the full data set is config. 5. a section across the faroe bank channel with temperature distribution on a typical day (colour) and vectorially averaged along-channel velocity (black lines) based on 70 days of observation with three moored adcps (shown). fig. 6. a water balance for the arctic mediterranean. 174 observed transport estimates between the north atlantic and the arctic mediterranean sidered, a fairly consistent seasonal cycle emerges (fig. 7) with maximum overflow flux in august. the overflow is generated by the thermohaline ventilation processes and they are, no doubt, most intense in winter. the long delay implies propagation speeds from the formation regions to the faroe bank channel on the order of centimetres per second. the amplitudes of seasonal variation in fig. 7 are about 10 20 % of the mean flow. we have no information on seasonal variation of the other two overflow paths in the iceland–scotland region, but jónsson (1999) found little seasonality in the denmark strait overflow both the total atlantic inflow to and the total overflow from the arctic mediterranean, therefore, seem to have only small seasonal variations in flux relative to their magnitudes. since they dominate the inflow and outflow, respectively, this correspondence is necessary for consistency. as noted already by worthington (1970), there must be a fairly tight balance between total inflow and total outflow. an imbalance of 1 sv would in the course of a month lead to sea level changes of about 20 cm averaged over the whole of the arctic mediterranean. long-term flux variations the measurements of overflow through the faroe bank channel (fig. 7) have a downward trend that might indicate a decreasing flux, but the period of observation is still too short to conclude anything on long-term flux changes for this flow or for the atlantic inflow based on the measurements alone. from the outset there has been the hope, however, that the detailed measurements carried out with the nordic woce system could enable us to formulate and calibrate models that use historic hydrographic and/or remote sensing data sets so that long-term changes could be investigated. this hope seems to have been fulfilled at least for the faroe bank channel overflow. the driving force for this overflow is the horizontal pressure gradient along the channel axis, which is created by the ventilation processes. the top of the cold overflow water, defined by the +0.5 °c isotherm, follows closely the σt = 28.0 isopycnal. in the atlantic, just off the exit of the channel, this isopycnal is below the sill level of the faroe bank channel, which is at about 840 m depth. upstream, in the norwegian sea, it is found much higher in the water column, but measurements at ocean weather ship station m (ows-m) document that this isopycnal deepened by about 50 m from 1950 to 2000. the total overflow flux defined as water colder then 3 °c has densities ranging down to σt = 27.8, and this isopycnal has also deepened at ows-m at similar rates since 1950. comparing these observations to the observations in the faroe bank channel, it has been proposed that this implies a weakening of the faroe bank channel overflow during the latter half of the 20th century (hansen et al. 2001). if not compensated by increases in other outflows, this implies a reduced atlantic inflow. outlook much effort was originally put into making the nordic woce observational system reliable and protected against fisheries. this has paid off in reduced equipment losses. as long as this situation continues and the necessary funding is available for consumables and instrument maintenance, the system can be expected to deliver ever more complete data sets that will allow ever more precise estimates of the typical fluxes as well as their seasonal variations. as the observational period is extended, the possibility of directly observing long-term changes will also increase. it must be noted, however, that the observational system does not have a complete coverage, even when we restrict the discussion to the iceland–scotland region. in this region, the atlantic inflow is well covered, but the overflow is only fig. 7. monthly averaged flux of isow water (dashed curve) and of nsdw+nsaiw (solid curve) overflow through the faroe bank channel. 175østerhus et al. 2001: polar research 20(1), 169–175 partly so since there is no monitoring of the overflows over the iceland–faroe ridge and the wyville-thomson ridge. the combined fluxes of these two overflows contribute about 20 % of the total overflow based on the available (but not very complete) evidence (hansen & østerhus 2000). in contrast to the faroe bank channel, these two ridges are fairly shallow, but wide, and the depth of the overflow water north-east of the ridges is close to sill-level for each of them. these ridges can therefore be expected to act like “safety valves” that switch between very large and very small overflow fluxes depending on the interface depth, and they would be an important component in a complete monitoring system. acknowledgements.—the nordic woce project was funded from the nordic environmental research programme for 1993–97 and by nordic research councils. continued support of the observational system has been provided from the european community through the veins project (mast iv) and the maia project (framework v). references dickson, r. r. & brown, j. 1994: the production of north atlantic deep water—sources, rates, and pathways. j. geophys. res. 99(c6), 12,319–12,341. ellett, d. j. 1998: norwegian sea deep water overflow across the wyville-thomson ridge during 1987–88. ices coop. re, rep. 225, 195–205. gould, w. j., loynes, j. & backhaus, j. 1985: seasonality in slope current transports n.w. of shetland. ices cm 1985/c:7. copenhagen: international council for the exploration of the sea. hansen, b., jónsson, s. s., turrell, w. r. & østerhus, s. 2000: seasonal variation in the atlantic water inflow to the nordic seas. ices cm 1999/l:21. copenhagen: international council for the exploration of the sea. hansen, b., larsen, k. m. h., østerhus, s., turrell, b. & jónsson, s. 1999: the atlantic water inflow to the nordic seas. int. woce newslett. 35, 33–35. hansen, b. & østerhus, s. 2000: north atlantic–nordic seas exchanges. prog. oceanogr. 45, 109–208. hansen, b., turrell, w. r. & østerhus, s. 2001: faroe bank channel overflow has decreased since 1950. nature 411, 927–930. hermann, f. 1967: the t–s diagram analysis of the water masses over the iceland–faroe ridge and in the faroe bank channel (overflow ‘60). rapports et procès-verbaux des réunions 157, 139–149. international council for the exploration of the sea. jónsson, s. 1999: the circulation in the northern part of the denmark strait and its variability. ices cm 1999/l:06. copenhagen: international council for the exploration of the sea. kristmannsson, s. s. 1998: flow of atlantic water into the northern icelandic shelf area, 1985–1989. ices coop. res. rep. 225, 124–135. østerhus, s., hansen, b., kristiansen, r. & lundberg, p. 1999: the overflow through the faroe bank channel. int. woce newslett. 35, 35–37. rahmstorf, s. & ganopolski, a. 1999: long-term global warming scenarios computed with an efficient coupled climate model. clim. change 43, 353–367. roach, a. t., aagaard, k., pease, c. h., salo, s. a., weingartner, t., pavlov, v. & kulakov, m. 1995: direct measurements of transport and water properties through the bering strait. j. geophys. res. 100(c9), 18443–18457. turrell, w. r., hansen, b., østerhus, s., hughes, s., ewart, k. & hamilton, j. 1999: direct observations of inflow to the nordic seas through the faroe shetland channel 1994–1997. ices cm 1999/l:01. copenhagen: international council for the exploration of the sea. worthington, l. v. 1970: the norwegian sea as a mediterranean basin. deep-sea res. 17, 77–84. schander.indd 119book reviews 2001: polar research 20(1), 119-120 astarte is probably one of the most difficult groups of bivalves for which to work out the systematics. the group is very old, it is widely spread and most of the known species are very variable in morphology. astarte species lack a planktonic larval stage, which is correlated with a large egg size (e.g. ockelmann 1965). this gives a potential for genetic drift in local populations. because of the difficulties of the group, the author of the book was warned against a study of astarte species, but when the result is at hand one can only be pleased that he did not heed this advice. the result is a delightful slim volume with beautiful color illustrations, informative text and easy-touse keys—all topped off with an interesting discussion. astarte is infamous for including numerous named species, varieties and forms, all very variable in morphology. the proliferation of names occurs both among the fossil species (e.g. spaink 1972; lauriat-rage 1982) and among the recent (e.g. smith 1881). astarte has a long and important fossil record, used for example as evidence for an early opening of the bering strait (marincovich & gladenkov 1999). the literature is extensive and the job to try to trace all the type material seems almost insuperable. there are therefore a number of reasons why a revision of arctic and baltic astarte has been awaiting. petersen does not investigate all astarte species in the region. in addition to the geographical delimitation (arctic and baltic), he also confines himself to specimens > 20 mm, and to specimens with a sharp margin. he has also limited his studies to material in the zoological museum (university of copenhagen) and the swedish museum of natural history in stockholm, omitting other collections in scandinavia and elsewhere. in spite of this, he manages to come up with six new arctic species and eight (!) new species from the baltic. he also re-describes three species and proposes a neotype for a. borealis (schumacher, 1817). so what about all those species? petersen obviously uses a very pragmatic species concept: if you can tell it apart from others, it is a new species. this may be problematic with a group such as astarte, where the lack of a larval stage in combination with a complicated phylogeographic history offers numerous possibilities for local varieties. what is considered a species may easily be a result of genetic drift in an isolated population. and isolated populations we have. astarte elliptica, for example, occurs very patchily along the swedish and norwegian coasts (own unpubl. observations). petersen himself admits in the acknowledgements that he is not pleased with all the species, but it is nonetheless the solution he came up with. besides this, we have the bordering regions —north america, the siberian arctic, the british isles and europe—that have not been investigated in this study. with the species strategy applied in this study, more species are bound to turn up, and there is an obvious risk for introducing synonymy. when it comes to the new baltic species it would be an advantage to compare the new recent species to the specimens of astarte commonly found in many quaternary beds in scandinavia (e.g. de geer 1910). petersen does not like fossil and recent species to share the same names, hence the new name a. neocrassa in this work, and previously mya neoovata and m. neouddevallensis (petersen 1999). this is a practice in which i have difficulty seeing any justification. to confer a separate name to the fossil or sub-fossil species it is in my opinion necessary to demonstrate a speciation event or break in the lineage, something petersen does not do convincingly. in my view, the fact that the fossil and the recent are separated in time is not enough. whether or not one accepts the multitude of book review when few become many—on a difficult group of bivalves review of g. høpner petersen 2001: studies on some arctic and baltic astarte species (bivalvia, mollusca). meddelelser om grønland. bioscience 52. copenhagen: danish polar center. 71 pp. isbn 87-90369-43-2. christoffer schander university of copenhagen, arctic station, box 504, dk-3953, qeqetarsuaq, greenland. 120 book reviews new species introduced in petersen’s work, the problems pointed out are fascinating. the new arctic and, especially, the new baltic species open up amazing possibilities for studying the genetics of isolated populations over long time periods. besides the characters used by petersen in this study numerous others are available. petersen himself is sceptical toward the use of biochemical methods for distinguishing species, mostly because of lack of funding and time, but also due to problems with species concepts. even if molecular methods are discarded, there is a range of other methods that also can be used. i have found the scanning electron microscope useful for studies of the astarte periostracum (schander 1992) and the structure of the shell matrix (unpubl.). saleuddin (1974) also used the sem to differentiate species of astarte. i also believe that sequencing of parts of the genome can yield important clues if it is possible to obtain material from the various localities mentioned by petersen, a problem he also points out. the new species are all described solely from the shell; surely the soft part anatomy will bring additional information. the sexual mode within astarte is known to vary between species (von oertzen 1972 and references therein) and ought to be investigated further. additional data concerning reproduction (e.g. von oertzen 1972) on astarte “borealis” and a. “elliptica” as well as biometric data (schaefer et al. 1985) clearly show that there is variation in different baltic populations. populations of a. “borealis” and a. “elliptica” have, for example, more separation of the spawning season in the bay of lübeck and the bay of mecklenburg than the other species in the study by von oertzen (1972). i sincerely hope that someone will pick up and expand on this interesting work by petersen. the subject is difficult but inspiring. given the situation in many museums, where shrinking personnel resources are diminishing the research possibilities, the prognosis is poor. i would love to see a couple of inspired phd students take on the task within the near future, clarifying what is going on with astarte in the baltic and in the arctic. i can recommend this book to anyone interested in bivalves, and to anyone interested in the consequences of genetic processes in isolated populations. references de geer, g. 1910: quaternary sea-bottoms in western sweden . geol. fören. stockholm förh. 32(5), 1–57. lauriat-rage, a. 1982: les astartidae (bivalvia) du redonien (pliocène atlantique de france) systematique, biostratigraphie, biogeographie. (the astartidae [bivalvia] of the redonian [atlantic pliocene of france].) mém. mus. natl. hist. nat. 48. paris. marincovich, l. jr. & gladenkov, a. y. 1999: evidence for an early opening of the bering strait. nature 397, 149–151. ockelmann, k. 1965: developmental types in marine bivalves and their distributions along the atlantic coast of europe. in l. r. cox & j. f. peake (eds.): proceedings of the first european malacological congress. 17–21 september 1962, london. pp. 25–35. conchological society of great britain and ireland, and malacological society of london. petersen, g. h. 1999: five recent mya species, including three new species and their fossil connections. polar biol. 22, 322–328. saleuddin, a. s. m. 1974: an electron microscopic study of the formation and structure of the periostracum in astarte (bivalvia). can. j. zool. 52, 1463–1471. schaefer, r., trutschler, k. & rumohr, h. 1985. biometric studies on the bivalves astarte elliptica, a. borealis and a. montagui in kiel bay (western baltic sea). helgol. meeresunters. 39, 245–253. schander, c. 1992: electrophoretic studies of the european species of astarte (mollusca, bivalvia) and some observations on the faroese fauna. (abstract.) norðurlandahúsið ársrit 1991–1992, 96. smith, e. a. 1881: observations on the genus astarte, with a list of the known recent species. j. conchol. 3, 196–232. spaink, g. 1972: descriptions of some species and subspecies of the genus astarte from the neogene of the netherlands. basteria 36, 21–29. von oertzen, j.-a. 1972: cycles and rates of reproduction of six baltic sea bivalves of different zoogeographic origin. mar. biol. 14, 143–149. plate 9, petersen 2001. astarte moerchi n. sp. holotype, from spitsbergen. printed with permission of the danish polar center. no job name b o o k r e v i e w por_175 228 review of biocultural diversity and indigenous ways of knowing: human ecology in the arctic, by karim-aly s. kassam (2009). calgary, ab: university of calgary press and the arctic institute of north america. 270 pp., 1 pocket map. isbn 978-1-55238-253-0. the perspective put forth in human ecology in the arctic by k.-a. kassam, although not one that is fundamentally foreign to northern social scientists, is intended to challenge what i suspect the author considers more orthodox and less socially aware approaches to research. focusing as it does on how indigenous northerners learn the environment (and how to learn what they learn), this book has its closest intellectual articulation in ingold’s approach to human–environment relations. the first two chapters, “relations between culture and nature: a critical consideration” and “human ecology reconceptualized: a lens for relations between biological and cultural diversity”, are the core of this work. in them, kassam calls for a structurally non-dichotomous view of nature and culture, and, thus, of what constitutes human ecology as a field of study. to accomplish this his prescription requires reorienting research toward the process by which indigenous northerners acquire and contextualize environmental knowledge. here, he also begins to detail how “best” to acquire such information methodologically, a process that is elaborated upon in chapters 4–6, based on his own research with the kola peninsula sami, ulukhaktok inuit and alaskan inupiaq at wainwright. his rendering of inupiaq knowledge of currents and winds, and their effect on sea ice, and thus whaling, is especially illuminating regarding the complex of information wainwright hunters must synthesize. it is difficult, at least for me, to summarize kassam’s belief that a recast human ecology must focus on phronesis (practical wisdom), if only because he draws his support from sources as diverse as aristotle, dostoevsky and e.o. wilson. what is clearer is his view that true human ecology research can only be achieved through the full participation of communities in all phases of the research process. in this way, indigenous ecological understanding can become the integrative bridge that moves research from a privileged to an affective activity. although i am generally sympathetic to kassam’s endeavour, i would be considerably more sympathetic if his two core conceptual chapters did not leave me feeling as if i had just sat through an overly long lecture. in point of fact, the call here for a biocultural synthesis through the concepts and methodology he presents strikes me as not all that different from the ideas and practices already being applied by cultural ecologists in and beyond the north. it is hard to argue against kassam’s ultimate objective: to see indigenous and non-indigenous knowledge fruitfully integrated, and it is not my intention to make such an argument. in point of fact, i suspect that very few northern researchers, regardless of discipline, reject the goal of better science that benefits northerners, and is benefited by them. at the same time, speaking for myself, kassam’s methodological and conceptual vision strikes me as no less rigid, at least as presented here, than northern science and scientists are (too) frequently accused of being. in no small sense, characterizing ulukhaktokmiut knowledge of animals and plants as phronesis, and scientists’ knowledge about caribou or land-locked arctic char as only episteme, seems to be not much more than a novel way of restating the (again the too oft repeated) argument that inuit traditional knowledge is holistic, and that the knowledge of visiting scientists is “merely” reductionist. (the overall presentation, in my view, also slights just how valuable long-term participant observation is in terms of moderating scientific rigidity.) in the end, although i am sympathetic to kassam’s overall aim—to strive for a more integrated science of the north—i remain firmly in the view that a diversity of theoretical orientations and methodologies does no harm to this aim. moreover, bringing other views about nature and culture to the north is much more in keeping with the most important reason to do science: that is, to achieve an exchange of ideas to the social benefit of all. correspondence george w. wenzel, department of geography, mcgill university, 805 sherbrooke street west, montréal h3a 2k6, canada. e-mail: wenzel@ geog.mcgill.ca polar research 29 2010 228 © 2010 the author, journal compilation © 2010 blackwell publishing ltd228 anderson.indd 225anderson & kaltin 2001: polar research 20(2), 225–232 most climate scientists do not question whether climate change might occur, but when and how this change will develop. the primary tools for prediction are coupled atmosphere–ocean global circulation models (gcms) run under different scenarios of atmospheric greenhouse gas increase. ongoing research is being performed to improve the physics in the various components of these models, but they can never have reliable predictive capability unless they include the relevant processes and feedbacks in an appropriate way. one aspect of these processes and feedbacks relates to the atmosphere–ocean exchange of carbon dioxide. how will the present-day driving forces be affected by climate change? the barents sea is a region where changes in the driving forces can have a significant impact on the thermohaline circulation, and therefore on climate. much of the warm, high salinity atlantic water that flows into the arctic ocean enters the barents sea. during transit through the barents sea, the atlantic water masses lose heat and thereby gain a sufficient density increase to produce intermediate and deep waters of the arctic ocean (e.g. schauer et al. 1997; anderson et al. 1999). the significant cooling of the surface waters in the barents sea also drives a flux of co2 from the atmosphere into the sea, a flux that is amplified by extensive biological primary production (walsh 1989; sakshaug et al. 1994). the formation of subsurface waters in the arctic mediterranean seas transport carbon, which partly include co2 of atmospheric origin (anderson et al. 1998a). the increased transport by the gulf stream during high nao index (hurrell 1995) conditions carbon fluxes in the arctic ocean— potential impact by climate change leif g. anderson & staffan kaltin because of its ice cover the central arctic ocean has not been considered as a sink of atmospheric carbon dioxide. with recent observations of decreasing ice cover there is the potential for an increased air–sea carbon dioxide flux. though the sensitivity of the carbon fluxes to a climate change can at present only be speculated, we know the responses to some of the forcing, including: melting of the sea ice cover make the air–sea flux operate towards equilibrium; increased temperature of the surface water will decrease the solubility and thus the air–sea flux; and an open ocean might increase primary production through better utilization of the nutrients. the potential change in air–sea co2 fluxes caused by different forcing as a result of climate change is quantified based on measured data. if the sea ice melts, the top 100 m water column of the eurasian basin has, with the present conditions, a potential to take up close to 50 g c m-2. the freshening of the surface water caused by a sea ice melt will increase the co2 solubility corresponding to an uptake of ~3 g c m -2, while a temperature increase of 1 °c in the same waters will out-gas 8 g c m-2, and a utilization of all phosphate will increase primary production by 75 g c m-2. l. g. anderson & s. kaltin, dept. of analytical and marine chemistry, göteborg university, se-412 96 göteborg, sweden. 226 carbon fluxes in the arctic ocean contributes to increased temperatures along the norwegian coast during winter. the increased temperature in the atlantic water (core of the west spitsbergen current) that has been observed in fram strait during the 1990s (swift et al. 1997) has been considered one cause of the sea ice thinning observed in the arctic ocean (rothrock et al. 1999). reduced sea ice cover will promote increased atmospheric warming via albedo feedback (morales maqueda et al. 1999). a decrease in the sea ice thickness can have effects on the headwaters (regions of intermediate and deep water formation) of the thermohaline circulation, most notably through the increased freshwater export into the greenland and iceland seas (steele et al. 1996). however, during recent years the modification of atlantic water in the barents sea has been emphasized as a significant contribution to the scotland–greenland overflow into the north atlantic ocean (mauritzen 1996). the barents sea region is very little affected by an increased freshwater outflow from the arctic ocean, and therefore the contribution to the scotland–greenland overflow will only be marginally altered. to predict future climate it is of great importance to improve our understanding of the processes controlling deep water formation and their sensitivity to possible climate change. the strength of the deep water formation will have a direct effect on the carbon cycle, and the strength of the deep water formation might be affected by the carbon cycle as the increasing atmospheric co2 content is the major cause of the potential climate change. to achieve an overall understanding of this coupling a description of the present functioning of the carbon cycle is required. it is also critical to assess how changes in the earth’s climate would alter cycling and partitioning of carbon between the ocean and atmosphere. specifically, changes in ocean dynamics and ocean thermodynamics may cause significant changes in air–sea co2 cycling. such feedbacks are not included in most coupled ocean–atmosphere climate models. instead, the future atmospheric concentration of co2 is prescribed in these models. because of its ice cover, the arctic ocean has not been considered as a sink of carbon dioxide. the biological activity in the central arctic ocean is small and the air–sea flux must be negligible compared to the shelf seas. in this presentation we evaluate the potential change of air–sea carbon dioxide flux in the arctic ocean caused by climate change. fig. 1. map of the eastern arctic ocean with the stations of the different cruises noted. the data used in this evaluation were from the regions indicated by boxes and marked 1 to 4. the norwegian atlantic current is abbreviated as nac. 227anderson & kaltin 2001: polar research 20(2), 225–232 present carbon fluxes the air–sea carbon flux have been estimated from budget computations to be 110×1012 g c yr-1 in the arctic mediterranean seas (arctic ocean and nordic seas) (lundberg & haugan 1996) and 24×1012 g c yr-1 in the arctic ocean, including the shelf seas (anderson et al. 1998b). if these estimates are comparable, uptake by the nordic seas equals 86×1012 g c yr-1. these estimates have significant uncertainties, but they point to the importance of the nordic seas for the uptake of co2 from the atmosphere. for the arctic ocean the shelf seas are the most important, with the uptake from the atmosphere being 9×1012 g c yr-1 in the barents sea (fransson et al. 2001). the other very important region is likely the chukchi sea. on a global perspective these fluxes are not impressive, but the potential for an increase in a climate change scenario is considerable. data and computation models the data used in this evaluation were collected during the acsys 1996 cruise to the eastern arctic ocean on r/v polarstern (augstein 1997) and a cruise to the barents sea in july 1999 on board the norwegian r/v jan mayen (with dr. p. wassmann, university of tromsø, as chief scientist). figure 1 shows the positions of the stations occupied during these cruises. standard analytical methods were applied for the determination of total dissolved inorganic carbon (ct), total alkalinity (at) and ph. total dissolved inorganic carbon was determined by gas extraction of an acidified water sample followed by coulometric titration (johnson et al. 1985, 1987). typically the precision was ± 4 µmol kg-1 and the accuracy was set by running a certified reference material supplied by a. dickson (scripps institution of oceanography) at each change of cell solution. total alkalinity was determined on board the ship by titrating the samples with 0.1 m hcl and measuring the change in ph with a potentiometric method (haraldsson et al. 1997). the precision fig. 2. depth profiles of (a) salinity, (b) temperature and (c) f co2 for all stations occupied during the acsys-96 cruise. crosses are from stations in the st. anna trough, filled triangles in the deep arctic ocean, and open circles along the shelf slope north of the laptev sea. (a) (b) (c) 228 carbon fluxes in the arctic ocean of the data was ± 2 µmol kg-1 and the accuracy was determined in the same way as for ct. the determination of ph was performed spectrophotometrically using m-cresol purple as indicator (clayton & byrne 1993; lee & millero 1995). the average standard deviation was 0.0006 ± 0.0006 and the accuracy was set by the accuracy of the temperature measurements and the accuracy in the determination of the stability constant of the dye, being approximately ± 0.002 (dickson 1993). the fugacity of carbon dioxide (f co2) was calculated with the co2 program developed by lewis & wallace (1998) as were all other computations of the carbonate system. the total hydrogen ion scale and the carbon dioxide constants from roy et al. (1993, 1994) were used. results and discussion first we investigate the present status with regard to f co2 saturation in the central arctic ocean, using the acsys-96 data (fig. 2). all of the top 250 m has an atlantic origin, where the upper ~100 m has a contribution of melted sea ice, resulting in lower salinity than the underlying more or less unmodified atlantic water (rudels et al. 1996). at the shelf slope north of the laptev fig. 3. the potential carbon uptake (pcu) computed as the difference between that computed from the observed at and a f co2 of 365 µatm and the measured ct, for four regions of the eastern arctic ocean (see fig. 1 for positions). note the different scales for the barents sea profile. 229anderson & kaltin 2001: polar research 20(2), 225–232 sea river runoff has been added, decreasing the salinity even further. the temperature signal is very variable below 100 m in the st. anna trough region, a result of the variable composition of the waters flowing off the shelf. the f co2 level computed from ct and ph show under-saturation all through the top 250 m, indicating that the surface water of the central arctic ocean could take up atmospheric co2 if sea ice were not hampering this. the f co2 is quite variable in the top 100 m, reflecting the different conditions in the regions, but more constant around 340 µatm in the deeper layers. the under-saturation of ~25 atm in the warm water at depths below 150 m indicates that, during its flow north in the norwegian atlantic current, the atlantic water does not have time to equilibrate with the atmosphere. this is a result of the heat loss to the atmosphere being a faster process than the air–sea flux of co2. to calculate the magnitude of the potential uptake by the surface water we used the measured at and a f co2 of 365 µatm (close to that in the atmosphere in 1996) to compute ct corresponding to that of a water in saturation with respect to the co2 (ct sat). the computation has been made for three regions occupied during the acsys-96 cruise (numbered 1 to 3 in fig. 1). furthermore, we made a corresponding computation for the data of the 1999 barents sea cruise. the mean profiles of the potential carbon uptake (pcu) equal to the difference between ct sat and the measured ct (ct meas) — pcu = ct sat ct meas —are presented in fig. 3. as mentioned above, the water is under-saturated well into the atlantic layer, corresponding to a pcu of about 20 µmol kg-1 at ~200 m depth in the barents sea. the pcu is larger in the eurasian basin relative to the st. anna trough, which could be explained by the larger fraction of the fram strait branch of atlantic water found in this region of the arctic ocean. the lowest pcu is found in the data over the makarov shelf slope, which might be due to a longer residence time over the shelves with more time to take up atmospheric co2. the largest pcu is found in the barents sea and this is caused by the seasonal consumption of co2 by photosynthesis. however, this water will spend a significant time in open water in the barents sea before entering the ice covered central arctic ocean. hence, it is not relevant to discuss this profile in relation to future climate caused changes in the ice cover. biological activity is much less in the central arctic ocean than in the shelf seas, making the data less seasonal dependent. furthermore, the seasonal signals that are transferred from the shelves into the central arctic ocean are smoothed out by the residence time of the surface water—on the order of 10 years. however, some of the variability seen in the top ~100 m close to the shelf seas can be a result of this effect. to make quantitative estimates for the central arctic ocean we assume that the top 100 m has a potential to take up atmospheric co2. integrating down to that depth gives potential uptakes for the st. anna trough region of 35 g c m-2, for the eurasian basin 48 g c m-2 and for the makarov shelf slope 7 g c m-2. these uptakes are only to balance the under-saturation of today and therefore only a one-time event. the annual uptake potential will be discussed below. it is only possible to increase the co2 uptake of ice-covered areas from the atmosphere by reducing ice cover, to get closer to equilibrium. however, with less ice cover other factors will also change, like salinity and possibly also temperature. if 2 to 3 m of ice (typical of multi-year ice in the eastern part of the arctic ocean) melts and the meltwater mixes into the top 100 m, the salinity decreases with 2 to 3 %. this freshening increases the solubility of co2 to a degree that it might take up an additional ~3 g c m-2. if the climate warms to the extent that the sea ice melts it might also cause a temperature increase of the surface water, where each degree results in a potential out-gassing of 8 g c m-2. another factor that will accompany a disappearance of the sea ice (at least during summer) is better light conditions for biological primary production. at present about 1/3 of the phosphate supplied to the central arctic ocean is consumed (fig. 4), most likely largely over the shelves, while the rest is available for photosynthesis within the central arctic ocean. if all the surplus phosphate were to be utilized it would correspond to a carbon consumption of 75 g c m-2, if the classical rkr phosphate–carbon ratio of 1:106 is used. it is not likely that all phosphate is used on an annual basis as other factors play an important role in the draw-down of carbon from the surface layer. these include the effect of phytoplankton and zooplankton species on sedimentation as well as remineralization in the surface layer at the end of the productive season. to address how the eco230 carbon fluxes in the arctic ocean logical system effects the draw-down of carbon and sedimentation is very complicated and far beyond the scope of this relatively simple computation of potential carbon flux changes with climate change. using the area of the whole deep central arctic ocean (5.8×1012 m2), we get potential uptake of atmospheric co2 from the different processes discussed above (table 1). the different potential uptakes cannot be summed up, but the relative importance of the different processes is illustrated. the observed pcu and increased export production are quite significant relative to the global uptake of anthropogenic co2 (~2000 × 1012 g c yr-1). to elucidate the annual potential uptake, we have to consider the volume input to the top 100 m of the central arctic ocean. inflow to the surface mixed layer and halocline (contributing to the top 100 m) is from the pacific and the atlantic (both over the barents sea and through fram strait) as well as from rivers. the question is what volume fluxes to apply for the different inflows. anderson et al. (1998b) used the literature values of the total exchange with the surrounding oceans and, by applying salt and mass balance, computed the contributions to the different water masses of the arctic ocean. in short, these add up to 0.9×106 m3 s-1 from the atlantic, 0.4×106 m3 s-1 from the pacific, and 0.1×106 m3 s-1 from runoff. if we take the sum of these inflows and multiply the estimated potential uptake of atmospheric carbon dioxide (divided by 100 m) by the different processes, we get the uptake from the atmosphere as shown in table 2. the potential uptakes used for table 1. the potential uptake of atmospheric co2 in the top 100 m of the total deep central arctic ocean by different processes. process potential uptake (1012 g c) pcua 278 salinity decrease of 2 % 14 temperature increase of 1 °c -46 export production corresponding to 50 % of the available phosphate 218 a the pcu value is taken from the eurasian basin profile. table 2. the potential annual uptake of atmospheric co2 by different processes in the deep central arctic ocean. the values are achieved by multiplying the average computed uptake of co2 by each process with the volume flux to the top 100 m (a total of 1.4×106 m3 s-1 according to anderson et al. 1998b). process potential uptake (1012 g c yr-1) pcua 21 salinity decrease of 2 % 1 temperature increase of 1 °c -4 export production corresponding to 50 % of the phosphate supply through st. anna trough 17 a the pcu value is taken from the st. anna trough profile. fig. 4. the phosphate distribution in the top 250 m of the eastern arctic ocean during the acsys-96 cruise. stations 6–16 are from the st. anna trough, 31–72 from the eurasian basin section, 73–90 from over the lomonosov ridge, 91–97 from the makarov shelf slope and 99–107 from the laptev sea shelf slope. the mean concentration in the atlantic layer water (250 to 500 m depth) equals 0.84 ± 0.06 µmol l-1. 231anderson & kaltin 2001: polar research 20(2), 225–232 these calculations are: 0.48 g c m-2 by pcu, 0.03 g c m-2 by freshening, -0.08 g c m-2 by 1 °c warming, and 37 g c m-2 by utilization of half the phosphate available. these estimates are based on the assumption that our estimated uptake potential is representative for the whole arctic ocean. the annual fluxes of table 2 are not large in a global view, but the observed pcu and increased export production is of the same order as the air–sea fluxes within the arctic ocean, including the shelf seas (anderson et al. 1998b). from the results presented in table 2 it is easy to evaluate the impact that changes in the strength of the oceanic circulation have on the air–sea co2 flux, as they are directly proportional. another effect of a disappearance of the sea ice cover is that it might increase vertical mixing and thus bring up more nutrients to the photic zone. this could be the situation if an open ocean persist under a time long enough for the resulting freshening to be exported to the adjacent seas. wallace et al. (1987) evaluated the vertical mixing coefficient (kz) to 2×10 -6 m2 s-1. if this were doubled, the increased supply of phosphate (fpo4) would according to fick ś law be: , where, according to fig. 4, making this computation and converting to carbon units we get: 0.3 × 10-3 (molp m-3) × 0.01 (m-1) × 2 × 10-6 (m2 s-1) × 60 × 60 × 24 × 365 (s yr-1) × 106 (molc molp-1) × 12 (g c molc-1) = 0.24 g c m-2 yr-1. this flux has to be multiplied by the area of the central arctic ocean to be compared to the values of table 2. this gives an increased annual export production of 1.4×1012 g c yr-1. this is about 10 % of the increased export production potentially caused by the horizontal supply of phosphate and is well within the uncertainties of that calculation. the vertical mixing of nutrients will also drive a flux of carbon to the surface layer, lowering the potential effect of this process in driving an air–sea flux of co2. all the above calculations have large uncertainties, but the objective of this contribution is to compute the potential changes for certain scenarios. hence, these numbers should be seen relative to each other, and as indicators of the potential magnitude of change in air–sea flux of co2 that might be caused by a climate change. for instance if the arctic ocean sea ice melts there is a potential effect to take up ~280×1012 g c yr-1 from the atmosphere just to reach co2 equilibrium and another ~220×1012 g c yr-1 by increased export production consuming half of the available phosphate. smaller alteration in the uptake might also be caused by changes in salinity and temperature coupled to this climatic effect. summary and conclusions we have shown that climate change involving significant decreases in the ice cover of the central arctic ocean could cause a one-time uptake of atmospheric co2 on the order of 500×10 12 g c, which is substantial relative to the global oceanic uptake of anthropogenic co2. this estimate is based on two processes: getting the surface water to equilibrium with the atmospheric co2 and an increased export production, consuming half of the available phosphate. on the other hand, the change in the annual uptake is more modest and in a scenario of an ice-free central arctic ocean (at least during the productive summer), the potential uptake of co2 from the atmosphere reaches ~40×1012 g c yr-1. this is the contribution by an export production corresponding to half the influxing phosphate and by reaching co2 saturation in the water flowing into the central arctic ocean. if the oceanic circulation strengthens or weakens this air–sea flux will change accordingly. it is not possible to foresee the magnitude of changes of the processes discussed, but at least it is possible to evaluate which processes have the largest impact and in what direction. acknowledgements.—this work is supported by grants from the swedish natural science research council. the authors acknowledge the organizers of the sverdrup symposium for giving us the opportunity to present this contribution. references anderson, l. g., chierici, m., fransson, a., olsson, k & jones, e. p. 1998a: anthropogenic carbon dioxide in the arctic ocean: inventory and sinks. j. geophys. res. 103(c12), 27,707–27,716. 232 carbon fluxes in the arctic ocean anderson, l. g., jones, e. p. & rudels, r. 1999: ventilation of the arctic ocean estimated by a plume entrainment model constrained by cfcs. j. geophys. res. 104(c6), 13,423–13,429. anderson, l. g., olsson, k. & chierici, m. 1998b: a carbon budget for the arctic ocean. glob. biogeochem. cycles 12, 455–465. augstein, e. 1997: the expedition arctic´96 of rv polarstern (ark xii) with the arctic climate system study (acsys). report on polar research 234. alfred wegener institute for polar and marine research. clayton, t. d. & byrne, r. h. 1993: spectrophotometric seawater ph measurements: total hydrogen ion concentration scale calibration of m-cresol purple and at-sea results. deep-sea res. i 40, 2115–2129. dickson, a. g. 1993: the measurement of sea water ph. mar. chem. 44, 131–142. fransson, a., chierici, m., anderson, l. g., bussman, i., kattner, g., jones, e. p. & swift, j. h. 2001: the importance of shelf processes for the modification of chemical constituents in the waters of the eastern arctic ocean. cont. shelf res. 21, 225–242. haraldsson, c., anderson, l. g., hassellöv, m., hulth, s. & olsson, k. 1997: rapid, high-precision potentiometric titration of alkalinity in the ocean and sediment pore waters. deep-sea res. i 44, 2031–2044. hurrell, j. w. 1995: decadal trends in the north atlantic oscillation: regional temperatures and precipitation. science 269, 676–679. johnson, k. m., king, a. e. & sieburth, j. m. 1985: coulometric tco2 analyses for marine studies: an introduction. mar. chem. 16, 61–82. johnson, k. m., sieburth, j. m., williams, p. j. & brandström, l. 1987: coulometric total carbon dioxide analysis for marine studies: automation and calibration. mar. chem. 21, 117–133. lee, k. & millero, f. j. 1995: thermodynamic studies of the carbonate system in seawater. deep-sea res. 42, 2035–2061. lewis, e. & wallace, d. w. r. 1998: program developed for co2 system calculations. ornl/cdiac-105. oak ridge, tn: carbon dioxide information analysis center, oak ridge national laboratory, us dept. of energy. lundberg, l. & haugan, p. m. 1996: a nordic sea–arctic ocean carbon budget from volume flows and inorganic carbon data. glob. biogeochem. cycles 10, 493–510. mauritzen, c. 1996: production of dense overflow waters feeding the north atlantic across the greenland–scotland ridge. 1. evidence for a revised circulation scheme. deep sea res. i 43, 769–806. morales maqueda, m. a., willmott, a. j. & darby, m. s. 1999: a numerical model for interdecadal variability of sea ice cover in the greenland–norwegian sea. clim. dyn. 15, 89–113. rothrock, d. a., yu, y. & maykut, g. a. 1999: thinning of the arctic sea-ice cover. geophys. res. lett. 26, 3469–3472. roy, r. n. roy, l. n., vogel, k. m., porter-moore, c., pearson, t., good, c. e., millero, f. j. & campbell, d. m. 1993: the dissociation constants of carbonic acid in seawater at salinities 5 to 45 and temperatures 0 to 45 °c. mar. chem. 44, 249–267. roy, r. n., roy, l. n. vogel, k. m., porter-moore, c., pearson, t., good, c. e., millero, f. j. & campbell, d. m. 1994: erratum for: the dissociation constants of carbonic acid in seawater at salinities 5 to 45 and temperatures 0 to 45 °c. mar. chem. 45, 337. rudels, b., anderson, l. g. & jones, e. p. 1996: formation and evolution of the surface mixed layer and halocline of the arctic ocean. j. geophys. res. 101(c4), 8807–8821. sakshaug, e. bjørge, a., gulliksen, b., loeng, h. & mehlum, f. 1994: structure, biomass distribution, and energetics of the pelagic ecosystem in the barents sea: a synopsis. polar biol. 14, 405–411. schauer, u., muench, r. d., rudels, b. & timokhov, l. 1997: the impact of eastern arctic shelf water on the nansen basin intermediate layers. j. geophys. res. 102(c2), 3371–3382. steele, m., thomas, d., rothrock, d. & martin, s. 1996: a simple model study of the arctic ocean freshwater balance 1979–1986. j. geophys. res. 101(c9), 20,833–20,848. swift, j. h. jones, e. p., aagaard, k., carmack, e. c., hingston, m., macdonald, r. w., mclaughlin, f. a. & perkin r. g. 1997: waters of the makarov and canada basins. deepsea res. ii 44, 1503–1529. wallace, d. w. r., moore, r. m. & jones, e. p. 1987:ventilation of the arctic ocean cold halocline: rates of diapycnal and isopycnal transport, oxygen utilization, and primary production inferred using chlorofluoromethane distribution. deep-sea res. 34, 1957–1979. walsh, j. j. 1989: arctic carbon sinks: present and future. glob. biogeochem. cycles 3, 393–411. larsen.indd 283larsen et al. 2002: polar research 21(2), 283�290 correlation of late holocene terrestrial and marine tephra mark ers, north iceland: implications for reservoir age changes gudrún larsen, jón eiríksson, karen luise knudsen & jan heinemeier the tephrochronology of the last 3000 years has been investigated in soil sections in north iceland and in a marine sediment core from the north ice landic shelf, 50 km offshore. tephra markers, identiþ ed with major ele ment geochemical analysis of volcanic glass shards, serve to correlate the mar ine and terrestrial records. hekla 3, the largest holocene tephra marker from the volcano hekla, in south iceland, dated to 2980 years bp, is used as the basal unit in the tephra stratigraphy. ams 14c dating of molluscs in the sediment core shows variable deviation from the tephrochronological age model, indicating that the reservoir age of the sea water mass at the coring site has varied with time. a standard mar ine reservoir cor rection of 400 14c years appears to be reasonable at the present day in the coastal and shelf waters around iceland, which are dom inated by the irminger current. however, values over 500 years are observed during the last 3000 years. we suggest that the intervals with increased and variable marine reservoir correction reß ect incursions of arctic water masses derived from the east greenland current to the area north of iceland. g. larsen & j. eiríksson, science institute, university of iceland, is-101 reykjavík, iceland; k. l. knudsen, dept. of earth sciences, university of aarhus, dk-8000 århus c, denmark; j. heinemeier, ams 14c dating laboratory, institute of physics and astronomy, university of aarhus, dk-8000 århus c, denmark. palaeoclimatic studies that extend beyond historical and instrumental records must rely on dating tech niques which enable reconstruction of time series for climate variability related prox ies. the purpose of the present study is to obtain inde pendent control on 14c dating of a high res olution sediment core obtained from an oceano graphic boundary region between atlantic and arctic water masses. the study is a part of the eur opean union holsmeer project, which focuses on climatic variability in shal low marine and coastal settings during the last 2000 years. the study area on the north icelandic shelf has the advantage of being close to the source volcan oes of holocene tephras, and it is located in an ocean og raphically sensitive boundary region between the relatively warm, saline irminger current and the east icelandic current, which forms a cold, low salinity tongue of surface water (fig. 1). the shallow north iceland shelf seabed is strongly affected by surface circulation in the area (eiríks son et al. 2000a). tephra markers that can be traced from volcanic source regions into the marine depositional environment provide inde pendent control on radiocarbon dates from that environ ment. the age of the tephra markers are based on historical records from iceland for the last 900 years, correlation to the greenland ice core chron ology, and radiocarbon dates of ter restrial material (see e.g. thorarinsson 1958, 1967, 1974; larsen & thorarinsson 1977; larsen 1982, 1984, 2000; sæmundsson 1991; grönvold et al. 1995; zielinski et al. 1997; haß idason et al. 2000). in this paper we demonstrate that a high res olution tephra stratigraphy can be used to link chronologies in the terrestrial and marine 284 correlation of late holocene terrestrial and marine tephra markers, north iceland environ ments. the investigation represents the þ rst detailed high resolution land�sea correlation of the regional terrestrial tephrochronology with the mar ine record, although several previous studies have demonstrated the importance of single tephra markers (e.g. lacasse et al. 1995, 1996; eiríks son et al. 2000a, 2000b; jennings et al. 2000). this allows us to compare two age models for a 3000 year sediment record from a mar ine shelf core north of iceland. one model is based on tephrochronological data, the other on accelerator mass spectrometry (ams) radiocarbon dating of the marine record. it is sug gested that discrepancies between the two age models are related to palaeoceanographic changes in the region and resulting changes in the reserv oir age of the water masses on the north icelandic shelf. materials and methods the calypso piston core md992275 (66° 33.06� n, 17° 41.59� w; 440 m water depth) was collected from the north icelandic shelf during the 1999 images cruise (fig. 1). the research methods used for the core material presented here have been described by eiríksson et al. (2000a) and by knudsen & eiríksson (2002). tephra horizons, observed during visual and xray inspection of the cores, were subsampled and sieved on a 63 µm sieve for the preparation of polished thin sections. major element geo chemical analysis of volcanic glass shards (table 1) were carried out by standard wavelength dispersal technique on an arl-semq microprobe at the geo logical institute, university of bergen, norway, with an accelerating voltage of 15 kv, a beam current of 10 na, and a defocused beam diameter of 6 12 µm. natural and synthetic minerals and glasses were used as standards. soil sections with tephra layers at six localities in north iceland (figs. 2, 3) provide detailed landbased tephrochronology for comparison with the mar ine records. subsamples of the terrestrial teph ras were prepared in the same way as the marine samples. samples from three sections have been analysed for major elements on the arlsemq microprobe at the university of bergen. the 14c datings of marine samples (table 2) were carried out at the ams 14c dating lab oratory at the university of aarhus, denmark. the dates have been corrected for natural isotopic frac tion ation by normalization to δ13c = -25 � vpdb, and calibrated with calib4 (stuiver et al. 1998a), using the marine model calibration curve (stuiver et al. 1998b). a standard reservoir cor rection of about 400 14c years (∆r = 0) is built into this model (see also andersen et al. 1989). in this paper we simply refer to calibrated years bp as years. tephra markers in north iceland and the north icelandic shelf the number of late holocene tephra layers from the last 3000 years in our soil sections in north iceland ranges from about 50 in the eastern part to about 25 in the western part. many of these tephra layers are probably too thin to form offshore deposits, while others are regional markers with high potential as offshore markers. tephra sections on land that are relevant for the present study are brieß y described below, and only the tephra layers detected so far in core md992275 will be treated. the svartárvatn lake lies about 90 km inland (1x on fig. 2i), north of the volcanic areas where fig. 1. location map showing the study area and the present-day surface ocean circulation in the northern north atlantic (based on hurdle 1986). depth contour interval 1000 m. also shown are the central volcanoes of the most relevant volcanic sys tems. loc ation of core md992275 is 66° 33.06� n, 17° 41.59� w. 285larsen et al. 2002: polar research 21(2), 283�290 holo cene eruption frequency has been highest. several soil sections were studied in the vicinity of the lake, and were merged to form a composite soil section showing the regional tephra stratigraphy, in which nearly 50 tephra layers younger than hekla 3 have been identiþ ed (fig. 3). forty of these tephras have been analysed by electron micro probe. the tephra layers originate from at least six volcanic systems, but the great majority has the chemical characteristics of the veidivötn� bárd arb unga system. the other volcanic systems include the gríms vötn, hekla, katla and snæfellsjökull systems (fig. 1). identiþ cation of tephra lay ers from the last 11 centuries was partly based on previous work (thorarinsson 1958, 1967, 1974; larsen 1982, 1984; haß idason et al. 2000), but work on the older tephra layers is still in progress. analyses of nine tephra layers tephra from the terrestrial sections in north iceland (svartár vatn, figs. 2, 3; and eyjafjördur, fig. 2) are presented in table 1a. the v-1477, v-1410, hekla 1300, hekla 1104, settlement (v-871/877) and katla 9th century tephras have all been described earlier (thor arinsson 1967; larsen 1982, 1984; ólafsson 1985). the settlement tephra was dated to 871 ± 2 and 877 ± 4 ad in the grip and gisp 2 ice cores, respectively (grönvold et al. 1995; zielin ski et al. 1997). we report for the þ rst time the presence in north iceland of the white acid tephra from an eruption in snæ fellsjökull volcano radiocarbon dated to 1750 ± 150 bp (steinthorsson 1967), previously reported only in west and north-west iceland (jóhannesson et al. 1981; roth 2000). peaty soil collected 0.6 2 cm below this tephra at svartárvatn yielded a date of 1855 ± 25 bp. analyses of the snæfellsjökull 1 tephra in the svartárvatn section are presented in table 1a as s-svart and those of a sample from a section 10 km west�north-west of the volcano fig. 2. (a�h) dispersal of eight of the tephra layers relevant for this study. the lines show the outermost isopach of each layer as known at present. this isopach is 0.5 cm for the v-1477 and v-871/877 tephra layers, 0.2 cm for hekla 1104 and 0.1 cm for the others. the central volcanoes of the relevant volcanic systems are indicated by capitals letters in 2i (full names on fig. 1). note that v-1477 and v-871/877 were erupted on long volcanic þ ssures belonging to the veidivötn�bárdarbunga system. key sections in north iceland are indicated by an x and a number. relevant for this study are 1: svartárvatn section; 2: breidavík section; 3: eyjafjördur section. 286 correlation of late holocene terrestrial and marine tephra markers, north iceland are included for comparison as sn-1. analyses of a basaltic tephra a few centimetres above the snæfellsjökull 1 tephra are presented in table 1a as g-svart. this tephra is characterized by tio2 in the range 2.1 2.4 weight % and is the older of two tephra layers in the key sections having these tio2 values (the other is 12th century ad). finally we present analyses of hekla 3 from the svartárvatn section. eight tephra horizons of homogeneous glass comp osition have been found in the uppermost 7 m of core md992275 (fig. 3, table 1b). several hori zons with abundant glass grains have also been ana lysed, but as the glass composition was hetero geneous the analyses are not included here except for a few grains with snæ fells jökull 1 composition from two such horizons (table 1c). the four youngest horizons in core md992275, at depths of 179, 209, 239 and 271 cm (table 1b), are correlated to the v-1477, v-1410, hekla 1300 and hekla 1104 ad tephra layers in the key sections (fig. 3). the 1477, 1410 and 1300 ad tephras are reported in an offshore deposit for the þ rst time, but hekla 1104 has also been found in other cores in the area (eiríksson et al. 2000a, 2000b). the two tephra horizons at 322 and 324 cm form a pair where the upper tephra has the chemical table 1 (opposite page). (a) representative microprobe glass analyses of tephra lay ers relevant to this study from key sections in north ice land. eight of the tephra samples are from the svart árvatn key section; the exceptions are the katla 9th cen tury tephra (sampled in the eyjafjördur key section) and the sn-1 sample (from a section on the snæfellsnes peninsula). the analyses do not show the complete composition range of each tephra layer. (b) representative microprobe glass an alyses of tephra horizons in the core md992275. five horizons with basaltic glass grains of homogeneous com position occur at depths of 179, 209, 322, 324 and 438 cm. three horizons with silicic glass grains of limited com positional range occur at depths of 239, 271 and 687 cm. (c) snæ fells jö kull 1 composition shards in md992275: selected analyses from two horizons (depths 431 cm and 455 cm) of glass grains with a variety of compositions. low totals are due to the small shard size of the tephra and the few analyses avail able. they are nevertheless strong indications of the grains� origin. fig. 3. tephra stratigraphy of core md992275 and the key sections breidavík and svartárvatn. all the tephra layers are shown as black lines without speciþ c thickness. asterisks indic ate that glass from the tephra layer or horizon has been ana lysed for major element composition. grey line shows inferred position of snæfellsjökull 1 in core md992275. stip pled line indicates tephra enriched horizons of mixed ori gin but containing snæ fellsjökull grains. tephra layers rele vant to this study are labelled with source (volcanic syst em) and eruption year. the volcanic systems are: veid ivötn�bárdarbunga (v), grímsvötn (g), hekla, katla and snæfellsjökull. 287larsen et al. 2002: polar research 21(2), 283�290 sio2 tio2 al2o3 feo mgo cao na2o k2o p2o5 v-1477 50.84 1.84 13.23 12.94 6.80 11.46 2.60 0.28 0.07 50.66 1.84 13.32 12.72 6.75 11.60 2.32 0.22 0.25 50.06 1.90 13.26 12.78 7.07 11.78 2.31 0.29 0.22 51.06 1.96 13.05 13.38 6.55 11.42 2.01 0.21 0.17 49.70 2.02 13.88 12.85 6.87 12.12 2.31 0.18 0.22 50.17 2.06 13.19 13.15 6.62 11.51 2.53 0.23 0.24 v-1410 49.54 1.91 13.86 12.31 7.07 11.82 2.53 0.28 0.06 49.81 1.96 13.99 12.35 7.21 12.04 2.35 0.25 0.02 48.65 1.85 14.00 12.48 6.81 11.78 2.33 0.27 0.20 49.47 1.92 13.72 12.40 7.04 11.85 2.35 0.25 0.11 49.09 1.84 14.13 12.26 6.92 11.64 2.33 0.18 0.28 49.33 1.83 14.19 12.44 6.95 11.76 2.29 0.25 0.25 hekla 1300 62.43 0.84 15.50 7.69 0.79 4.28 4.59 2.00 0.36 62.23 0.92 14.85 8.15 0.92 4.13 4.51 2.04 0.48 61.61 1.10 15.22 8.74 1.19 4.71 4.11 1.77 0.37 61.30 1.02 14.99 9.59 1.51 4.68 4.28 2.03 0.26 60.29 1.34 14.66 9.97 1.68 4.94 4.04 1.81 0.57 58.47 1.26 15.90 10.10 2.08 5.57 4.23 1.56 0.48 hekla 1104 73.76 0.26 13.67 2.62 0.03 1.75 4.41 2.89 0.06 72.82 0.21 14.21 3.00 0.05 1.88 4.53 2.70 0.00 72.69 0.25 14.08 3.26 0.11 1.92 4.23 2.58 0.00 72.41 0.27 14.20 3.31 0.12 2.01 4.33 2.66 0.00 71.69 0.29 14.47 3.24 0.01 1.90 4.52 2.84 0.00 70.68 0.32 14.40 3.34 0.09 1.91 4.36 2.89 0.13 v-871 / 877 48.47 1.94 13.58 12.65 6.74 11.45 2.55 0.22 0.22 49.38 1.92 13.68 13.05 6.36 11.03 2.47 0.29 0.09 49.33 1.86 13.71 12.70 6.30 11.35 2.43 0.21 0.27 48.85 1.86 13.70 12.85 6.79 11.39 2.34 0.17 0.20 49.93 1.82 13.56 12.81 6.51 11.19 2.20 0.26 0.22 49.59 1.77 13.58 12.94 6.39 11.22 2.36 0.30 0.19 k 9th century 49.53 4.61 13.17 15.13 4.45 9.37 2.42 0.82 0.55 48.83 4.43 13.46 15.75 4.44 9.40 2.96 0.77 0.46 48.55 4.83 13.28 14.88 5.27 10.42 2.59 0.86 0.47 48.04 4.74 13.12 15.55 4.87 9.80 3.00 0.86 0.64 47.75 4.56 12.94 15.55 4.90 9.46 2.59 0.90 0.60 47.52 4.35 13.09 15.02 4.91 9.74 2.64 0.81 0.49 g-svart 49.68 2.42 13.92 12.31 6.32 11.02 2.39 0.43 0.20 49.36 2.34 14.60 12.12 6.70 11.35 2.64 0.38 0.31 49.43 2.29 14.12 12.04 6.63 11.45 2.38 0.44 0.31 48.95 2.27 14.24 12.26 6.40 11.20 2.51 0.42 0.16 49.57 2.26 14.38 12.12 7.03 11.52 2.58 0.35 0.23 50.12 2.17 14.16 11.94 6.76 11.37 2.53 0.40 0.15 s-svart 67.48 0.38 15.63 4.11 0.21 1.81 4.77 4.19 0.05 67.42 0.48 15.80 4.25 0.35 1.72 5.62 4.49 0.09 66.08 0.41 15.98 4.00 0.28 2.00 5.61 4.01 0.00 65.46 0.51 15.99 4.62 0.33 2.08 5.39 4.04 0.00 65.42 0.45 15.96 4.39 0.34 2.03 5.64 4.02 0.02 64.96 0.47 15.74 4.40 0.30 1.94 5.21 4.05 0.01 sn-1 69.32 0.33 15.54 3.37 0.16 1.30 5.12 4.59 0.02 67.63 0.41 15.61 3.83 0.30 1.61 5.14 4.51 0.08 67.32 0.42 15.70 4.29 0.49 1.94 5.06 4.38 0.04 67.16 0.36 15.22 4.36 0.24 1.57 4.70 4.41 0.00 66.36 0.40 15.71 4.40 0.32 1.61 5.25 4.34 0.25 65.81 0.36 16.34 4.20 0.44 2.31 5.17 3.93 0.02 hekla 3 71.76 0.22 14.48 3.04 0.12 1.98 4.43 2.66 0.01 71.45 0.25 14.20 3.13 0.14 2.07 4.59 2.52 0.06 71.12 0.28 14.26 3.04 0.10 1.96 4.69 2.66 0.11 71.11 0.26 14.07 3.05 0.16 1.97 4.63 2.47 0.00 70.43 0.19 14.31 3.16 0.14 2.04 4.48 2.67 0.02 69.30 0.14 14.31 3.12 0.03 2.05 4.62 2.54 0.03 sio2 tio2 al2o3 feo mgo cao na2o k2o p2o5 md992275 / 179 49.66 1.90 13.94 13.36 6.65 11.49 2.44 0.30 0.12 49.47 1.94 13.32 13.46 6.30 11.50 2.51 0.23 0.24 48.86 1.94 14.21 12.88 6.49 11.65 2.23 0.23 0.31 48.15 2.01 13.41 12.66 7.56 12.48 2.14 0.25 0.11 49.25 2.02 13.18 13.67 6.26 11.56 2.40 0.31 0.16 50.65 2.09 12.96 13.71 6.60 11.43 2.21 0.23 0.15 md992275 / 209 51.53 1.83 13.25 13.10 6.10 11.81 2.21 0.25 0.12 51.05 1.93 13.26 12.68 6.57 12.04 2.15 0.23 0.15 50.94 1.96 14.61 12.53 7.32 11.05 2.39 0.19 0.24 50.62 1.76 14.13 12.85 6.87 11.49 2.26 0.21 0.19 50.31 1.91 14.38 13.11 6.55 10.98 2.38 0.24 0.21 49.36 1.83 14.19 12.68 7.01 11.59 2.30 0.23 0.17 md992275 / 239 61.73 1.22 15.64 9.13 1.63 4.95 4.29 1.76 0.41 61.20 1.02 15.21 8.95 1.55 4.95 4.08 1.80 0.33 61.11 1.15 15.73 9.34 1.49 5.00 4.33 1.76 0.58 60.05 1.32 15.31 8.76 1.58 4.49 4.32 1.67 0.39 58.74 1.12 15.53 9.30 1.38 5.06 4.08 1.77 0.52 57.59 1.15 15.72 9.44 1.62 5.34 4.38 1.67 0.23 md992275 / 271 74.19 0.20 14.39 3.13 0.08 2.13 4.11 2.81 0.01 72.69 0.25 13.38 3.24 0.11 2.05 4.50 2.65 0.03 72.65 0.22 14.46 3.17 0.00 2.08 4.67 2.84 0.00 72.04 0.30 14.24 3.24 0.14 2.06 4.61 2.77 0.11 70.74 0.31 13.68 3.29 0.08 1.99 4.30 2.62 0.07 69.36 0.24 13.94 4.73 0.06 4.40 5.16 1.62 0.04 md992275 / 322 48.61 1.75 14.26 12.51 6.76 11.27 2.39 0.26 0.15 50.54 1.88 13.89 12.85 6.88 11.59 2.11 0.23 0.31 48.82 1.97 13.61 13.22 6.37 10.83 1.77 0.20 0.11 49.89 2.03 13.67 12.92 6.69 11.27 2.46 0.18 0.07 49.49 2.06 14.04 11.85 7.37 12.32 2.42 0.22 0.18 49.49 2.09 13.67 12.53 6.91 11.26 2.46 0.23 0.07 md992275 / 324 48.12 4.48 13.59 15.32 4.89 10.02 2.91 0.94 0.55 47.66 4.40 12.89 15.04 4.83 10.02 2.99 0.72 0.62 47.59 4.96 13.15 15.17 4.59 9.92 3.06 0.88 0.43 47.45 4.70 13.38 14.71 4.78 9.86 3.14 0.92 0.53 47.40 4.72 12.74 14.71 4.55 9.94 2.98 0.86 0.67 46.32 4.50 13.45 14.81 4.77 9.99 3.12 0.76 0.43 md992275 / 438 49.68 2.35 14.18 12.34 6.32 11.31 2.66 0.29 0.34 49.68 2.30 14.38 12.41 7.17 11.34 2.46 0.32 0.14 49.58 2.18 14.67 12.24 6.74 11.04 2.35 0.41 0.28 49.16 2.20 14.52 12.16 6.77 11.25 2.49 0.43 0.20 49.13 2.26 14.35 12.26 6.88 11.18 2.40 0.34 0.23 49.12 2.33 14.47 12.15 6.54 10.95 2.56 0.30 0.26 md992275 / 687 71.45 0.18 14.37 3.19 0.00 2.00 5.02 2.46 0.00 71.16 0.26 14.29 3.18 0.04 1.98 4.92 2.38 0.00 70.21 0.03 14.21 3.20 0.09 1.97 4.39 2.36 0.00 69.66 0.19 14.05 3.18 0.22 2.15 4.48 2.39 0.11 67.28 0.33 15.06 5.34 0.30 3.08 4.59 2.17 0.07 65.42 0.45 15.18 6.12 0.38 3.51 4.64 2.04 0.12 sio2 tio2 al2o3 feo mgo cao na2o k2o p2o5 431 65.44 0.49 15.60 3.91 0.29 1.75 5.16 4.46 0.10 63.70 0.38 15.19 3.95 0.32 1.66 5.20 4.00 0.00 455 64.46 0.47 15.93 4.86 0.52 2.31 5.05 3.95 0.03 60.82 0.59 15.81 4.74 0.44 2.08 4.49 3.80 0.12 (a) (b) (c) 288 correlation of late holocene terrestrial and marine tephra markers, north iceland signature of the veidivötn�bárdarbunga system and the lower one has that of the katla system. three such pairs have been identiþ ed in the key sections svartárvatn and eyjafjördur. the youngest pair is the settlement tephra and the 9th century katla tephra, the second youngest pair is from the early 9th / late 8th century ad and the third is much older. the chemical signature þ ts best with the late 9th century tephras. the settlement tephra has not yet been traced to the north coast of iceland (fig. 2e shows the 0.5 cm isopach) despite its volume of 5 km3 as freshly fallen tephra (recalculated from larsen 1984), but offshore deposition is likely considering the magnitude of the eruption. below 3.3 m the core has only partly been searched for tephra horizons. one distinct tephra hor izon has been detected at 438 cm in the core (fig. 3). it consists of homogeneous basaltic glass and has tio2 values in the 2.1 2.4 weight % range that allow it to be correlated to the g-svart teph ra in the svartárvatn section. chemically identi cal grains to those of snæfellsjökull 1 have been found in two of the glass-rich horizons at depths of 431 and 455 cm in core md992275 (shown as stip pled lines in fig. 3), together with a var i ety of acid, intermediate and basaltic glass grains. examples of glass grains with snæ fells jökull 1 compo sition are presented in table 1c. a tephra hori zon consisting entirely of acid glass with the chem ical characteristics of the hekla system occurs at 687 cm. the composition and range is con sis tent with the hekla 3 tephra in the svart ár vatn section as well as the hekla 3 tephra iden ti þ ed in core hm107-03 by eiríksson et al. (2000a). radiocarbon dates of molluscs from core md 992275 are listed in table 2 as well as the age of dated tephra markers. the results are plotted against core depth in fig. 4, which shows an age model based on tephrochronology as well as the cal ibrated radiocarbon dates. above the hekla 3 teph ra marker, over 100 years need to be subtracted from the radiocarbon dates to bring them to the tephra age model level. discussion the tephrochronological age model for core md992275 (fig. 4) is at present based on þ ve well-constrained dates of tephra layers younger than 1130 years (the time span of iceland�s recorded history) and on terrestrial radiocarbon dates on two older tephra layers: snæfellsjökull 1 and hek la 3. a straight-line þ t age model between the tephra layers is presented, and slight adjustments can be expected as more terrestrial dates become available. the date of the hekla 3 marker tephra is well-constrained (dugmore et al. 1995). the two dates on the snæfellsjökull 1 tephra are in reason able agreement, considering that the 1855 ± 25 date is on a soil slice separated from the tephra by 0.6 cm and the 1750 ± 150 date is on soil im mediately below. the presence of the snæfellsjökull 1 tephra in the core is manifested by the occur rence of glass grains in the sediment below and above the g-svart tephra. the lowest level of iden tiþ ed glass grains with snæfellsjökull 1 composition is at 455 cm in core md992275 and such grains are also found above the g-svart tephra. these grains are considered redeposited, and the level of the primary snæfellsjökull 1 tephra is tentatively estimated at 460 cm depth (fig. 3), slightly below the level of their þ rst appear ance. previous age model investigations on the north icelandic shelf have shown discrepancies between 400 year reservoir age corrected radiofig. 4. age�depth diagram for core md992275. two possible age models are shown. the solid line indicates an age model based only on tephra markers (tephrochronological age model). the ams 14c dates are shown with ± one standard deviation (see also table 2). 289larsen et al. 2002: polar research 21(2), 283�290 carb on age models and tephrochronological age models, both for the upper holocene and the late glac ial (eiríksson et al. 2000a, 2000b; knud sen & eir íks son 2002). they concluded that a southward shift of the polar front ca. 3000 years ago, indi cated by benthic and planktonic foraminifera, coincided with an increase of about 130 years in the reservoir age correction needed to þ t their radio carbon and tephrochronological age models. this value corresponds approximately to the reserv oir age of ca. 550 14c years reported by taub er & funder (1975). before 3000 years bp, a 400 year correction was sufþ cient back to ca. 4500 years bp. the results presented here show that core site md992275 has been extensively affected by arctic water for the past 3000 years. at present, the site is closer to the polar front than site hm107-03 studied by eiríksson et al (2000a) and knud sen & eiríksson (2002). the time lag between the tephra age model and the calibrated radiocarbon dates in core md992275 increases sharply to at least 400 years after the deposition of hekla 3, decreasing to nearly zero at ca. 1900 years bp. above that there is a lag of 100 200 years with broad maxima at around 1400, 600 and 300 years bp. more radiocarbon dates and a tighter control on the tephrochronology above hekla 3 is necessary for the quanti þ cation of these age deviations and their frequency, as well as high resolution studies of palaeoceanographic prox ies throughout the core. this work is cur rently in progress within the holsmeer project. conclusions 1) nearly 50 tephra layers from the last 3000 years have been documented in key sections in north ice land, providing a basis for high resolution terrestrial tephra stratigraphy to which marine records can be correlated. 2) reliable correlations between terrestrial and marine tephra layers can be based on geochemical signatures and mapping of the distribution of these layers on land and on the sea ß oor. 3) correlation of eight tephra horizons in marine core md992275 to dated tephra layers in key sections on land allows the construction of a tephro chronological age model for core md992275 table 2. radiocarbon dates and ages of dated tephra markers in core md992275. all radiocarbon samples were calibrated with calib4 (stuiver et al. 1998a, 1998b). the age of historical tephra layers is reported as calendar years bp (before 1950), rounded off to the nearest decade. radio carbon dates of the pre-settlement tephra layers are on ter restrial material below the tephras; for details on hekla 3 see dugmore et al. (1995). tephra marker depths correspond to the base level of each unit. a standard reservoir correction of about 400 years for marine samples is built into the radiocarbon model. ° = assumed standard δ13c value. depth cm. lab. no. material; 14c age (bp) cal. age(s) bp cal. ± 1 σ δ13c md992275 dated tephra layer ± 1 σ r = 400 (bp) 63 64 aar-7116 thyasira equalis 695 ± 45 310 410 290 -7° 100 101 aar-7117 thyasira cf. equalis 785 ± 40 440 470 410 -6.85 122 123 aar-6089 siphonodentalium lobatum 895 ± 45 510 530 480 +0.70 133 135 aar-7118 thyasira equalis 815 ± 45 460 490 430 -8.98 162 163 aar-7119 nuculana sp. 945 ± 35 530 550 510 +0.51 179 v-1477 470 209 v-1410 540 220 224 aar-7120 thyasira equalis, thyasira sp. 1265 ± 45 790 880 740 -8.69 239 hekla 1300 650 259 260 aar-7121 thyasira equalis 1420 ± 50 950 1000 920 -8.00 272 hekla 1104 850 287 291 aar-6931 thyasira equalis 1555 ± 35 1110 1160 1060 -6.84 321 settlement layer 1080 332 333 aar-7122 siphonodentalium lobatum 1710 ± 45 1270 1290 1230 +0.44 373 374 aar-6932 siphonodentalium lobatum 1905 ± 40 1450 1510 1400 +0.69 381 382 aar-6933 bathyarca glacialis 2020 ± 40 1570 1620 1530 +1.65 ca. 460 ll-1169a snæfellsjökull 1 (peat) 1750 ± 150 1690 1630 1860 1520 ca. 460 kia17232 snæfellsjökull 1 (peaty soil) 1855 ± 25 1820 1820 1730 -24.6 472 473 aar-6934 cf. dentalium entalis 2245 ± 40 1850 1890 1810 +0.72 512 513 aar-6935 cf. siphonodentalium lobatum 2530 ± 45 2180 2290 2120 +0.91 537 538 aar-7123 thyasira equalis 2680 ± 65 2340 2440 2310 -6.80 582 584 aar-6936 thyasira sp. 3110 ± 70 2860 2960 2780 1° 632 633 aar-7124 thyasira cf. equalis 3345 ± 45 3200 3260 3150 -8.05 687 hekla 3 (peat) 2879 ± 34 2990 2970 3080 2950 696 697 aar-6937 siphonodentalium lobatum 3265 ± 50 3080 3160 3010 +0.96 796 797 aar-6938 bathyarca glacialis 3795 ± 50 3710 3810 3660 +2.11 290 correlation of late holocene terrestrial and marine tephra markers, north iceland and comparison between marine and ter restrial dates. 4) discrepancies between reservoir corrected radiocarbon dates of molluscs and the tephrochronological age model vary from tens to hundreds of years. 5) the discrepancies between the radiocarbon and tephrochronological age models may be related to incursions of arctic water masses into the northern north atlantic to the north and east of iceland. acknowledgements.�this paper is a contribution to the european union 5th framework holsmeer project (contract no. evk2-ct-2000-00060), which supported þ eld work, dating and geochemical analysis. core material was obtained from the md9922 images cruise in 1999. we are grate ful to the institut français pour la recherche et la tech nologie polaires for the images coring operations on board the mari on dufresne. participation in the cruise and the sci entiþ c work was sup ported by grants from the icelandic re search council and the danish natural science research council. we thank prof. l. a. simonarson, university of ice land, for identifying mol luscs for the radiocarbon dating. we thank o. tumyr and h. haß idason at the university of berg en for assistance and discussions at various stages of this project. references andersen, g. j., heinemeier, j., nielsen, h. l., rud, n., johnsen, s., sveinbjörnsdóttir, á. e. and hjartarson, á. 1989: ams 14c dating on the fossvogur sediments, iceland. radio carbon 31, 592�600. dugmore, a. j., cook, g. t., shore, j. s., newton, a. j., edwards, k. j. & larsen, g. 1995: radiocarbon dating tephra layers in britain and iceland. radiocarbon 37, 379�388. eiríksson, j., knudsen, k. l., haß idason, h. & heinemeier, j. 2000a: chronology of late holocene climatic events in the north ern north atlantic based on ams 14c dates and tephra markers from the volcano hekla, iceland. j. quat. sci. 15, 573�580. eiríksson, j., knudsen, k. l., haß idason, h. & henriksen, p. 2000b: late-glacial and holocene palaeoceanography of the north icelandic shelf. j. quat. sci. 15, 23�42. grönvold, k., óskarsson, n., johnsen, s. j., clausen, h. b., ham mer, c. u., bond, g. & bard, e. 1995: ash layers from ice land in the greenland grip ice core correlated with oce an ic and land sediments. earth planet. sci. lett. 135, 149�155. haß idason, h., eiriksson, j. & kreveld, s. v. 2000: the tephro chronology of iceland and the north atlantic region during the middle and late quaternary: a review. j. quat. sci. 15, 3�22. hurdle, b. g. 1986: the nordic seas. new york: springer. jennings, a., syvitski, j., gerson, l., grönvold, k., geirsdót tir, á., hardardóttir, j., andrews, j. & hagen, s. 2000: chronology and paleoenvironments during the late weichselian deglaciation of the southwest iceland shelf. boreas 29, 167�183. jóhannesson, h., flores, r. m. & jónsson, j. 1981: a short account of the holocene tephrochronology of the snæfellsjökull central volcano, western iceland. jökull 31, 23�30. knudsen, k. l. & eiríksson, j. 2002: application of tephrochronology to the timing and correlation of palae oceanographic events recorded in holocene and lateglacial shelf sediments off north iceland. mar. geol. 191, 165�188. lacasse, c., sigurdsson, h., carey, s., paterne, m. & guichard, f. 1996: north atlantic deep-sea sedimentation of late quat ernary tephra from the iceland hotspot. mar. geol. 129, 207�235. lacasse, c., sigurdsson, h., jóhannesson, h., paterne, m. & carey, s. 1995: source of ash zone 1 in the north atlantic. bull. volcanol. 57, 18�32. larsen, g. 1982: gjóskutímatal jökuldals og nágrennis. (teph ro chronology of the jökuldalur area.) in h. thórarinsdót tir et al. (eds.): eldur er í nordri. (fire in the north.) pp. 51�65. reykjavík: sögufélag. larsen g. 1984: recent volcanic history of the veidivötn þ ssure swarm, southern iceland�an approach to volcanic risk assessment. j. volcanol. geotherm. res. 22, 33�58. larsen, g. 2000: holocene eruptions within the katla volcanic system, south iceland: characteristics and environmental impact. jökull 49, 1�28. larsen, g. & thorarinsson, s. 1977: h4 and other acid hekla tephra layers. jökull 27, 28�46. ólafsson, g. 1985: gjóskulög í austurdal og vesturdal, skaga þ rdi. (tephra layers in austurdalur and vesturdalur, skagafjördur.) bsc thesis, university of iceland. roth, v. 2000: um nákudungslagakambinn í landi bæjar í hrútaþ rdi. (the zirphaea crispata deposit at bær in hrútafjördur.) bsc thesis, university of iceland. sæmundsson, k. 1991. jardfrædi kröß ukerþ sins. (geology of the kraß a volcanic system.) in a. gardarson & á. einars son (eds.): náttúra mývatns. (the natural history of lake mývatn.) pp. 25�95. reykjavík: hid íslenska náttúrufrædifélag. steinthorsson, s. 1967: tvær nýjar c14 aldurákvardanir á ös kulögum úr snæfellsjökli. (two new c14 dates on tephra lay ers from snæfellsjökull.) náttúrufrædingurinn 37, 236�238. stuiver, m., reimer, p. j., bard, e., beck, j. w., burr, g. s., hughen, k. a., kromer, b., mccormack, g., van der plicht, j. & spurk, m. 1998a: intcal98 radiocarbon age calibration, 24,000�0 cal bp. radiocarbon 40, 1041�1083. stuiver, m., reimer, p. j. & braziunas, t. f. 1998b: highprecision radiocarbon age calibration for terrestrial and marine samples. radiocarbon 40, 1127�1151. tauber, h. & funder, s. 1975: 14c content of recent molluscs from scoresby sund, central east greenland. grønl. geol. unders. rapp. 75, 95�99. thorarinsson, s. 1958: the öræfajökull eruption of 1362. acta nat. isl. ii 2. thorarinsson, s. 1967: the eruptions of hekla in historical times. in t. einarsson (ed.): the eruption of hekla 1947�1948 i. pp. 1�170. reykjavík: societas scientiarum islandica. thorarinsson, s. 1974: vötnin stríd. saga grímsvatnagosa og skeidarárhlaupa. (the swift-ß owing rivers. grímsvötn eruptions and glacial ß oods in skeidará.) reykjavík: bók aút gáfa menningarsjóds. zielinski, g. a., mayewski, p. a., meeker, l. d., grönvold, k., germani, m. s., whitlow, s., twickler, m. s. & taylor, k. 1997: vol canic aerosol records and tephrochronology of the sum mit, greenland, ice cores. j. geophys. res. 102, 26 625�26 640. sediment transport to the laptev sea-hydrology and geochemistry of the lena river v. rachold, a. alabyan, h.-w. hubberten, v. n. korotaev and a. a, zaitsev rachold, v., alabyan, a., hubberten, h.-w., korotaev, v. n. & zaitsev, a. a. 1996: sediment transport to the laptev sea-hydrology and geochemistry of the lena river. polar research 15(2), 183-196. this study focuses on the fluvial sediment input to the laptev sea and concentrates on the hydrology of the lena basin and the geochemistry of the suspended particulate material. the paper presents data on annual water discharge, sediment transport and seasonal variations of sediment transport. the data are based on daily measurements of hydrometeorological stations and additional analyses of the spm concentrations carried out during expeditions from 1975 to 1981. samples of the spm collected during an expedition in 1994 were analysed for major, trace, and rare earth elements by icp-oes and icp-ms. approximately 700 h3 freshwater and 27 x lo6 tons of sediment per year are supplied to the laptev sea by siberian rivers, mainly by the lena river. due to the climatic situation of the drainage area, almost the entire material is transported between june and september. however, only a minor part of the sediments transported by the lena river enters the laptev sea shelf through the main channels of the delta, while the rest is dispersed within the network of the lena delta. because the lena river drains a large basin of 2.5 x lo6 km2, the chemical composition of the spm shows a very uniform composition. in contrast, smaller rivers with more restricted catchment areas exhibit significant differences. v . rachold and h.-w. hubberten, alfred wegener institute for polar and marine research, research department potsdam, telegrafenberg a43, d14473 potsdam, germany; a. alabyan, v. n. korotaev and a . a. zaitsev, moscow state universiry, geography department, moscow, russia, 119899. introduction the extent, thickness and drift patterns of arctic sea-ice cover control the heat and gas exchange between ocean and atmosphere and effect ocean circulation and the global climatic system (aagaard et al. 1985; clark 1990). one of the major goals of paleoclimate research is therefore to understand the variations in arctic sea ice distribution and circulation during the climate cycles of the past. today large amounts of sea ice are formed in the broad and shallow eurasian shelf regions. as the laptev sea is the main source area for sea ice feeding the transpolar drift (dethleff et al. 1993; wollenburg 1993; kassens & karpij 1994; niirnberg et al. 1994; eicken et al. 1995; reimnitz et al. 1995), it is considered to be one of the key areas in the entire arctic ocean. the laptev sea is strongly influenced by continental runoff. the main portion of water and sediments is transported through the lena river which is the second largest river in russia and the eighth largest in the world in terms of water discharge (milliman & meade 1983). other rivers-the jana, the chatanga, the olenek, the omoloi and the anabar-play a minor role in the laptev sea water mass formation. the sediments supplied by rivers are partly incorporated into sea ice and transported from the laptev sea shelf across the arctic ocean and through the fram strait via the transpolar drift (bischof et al. 1990; eggertsson 1994; reimnitz et al. 1994; stein & korolev 1994). for that reason the characterisation and quantification of recent sediment transport from the eurasian continent to the arctic ocean and its variations between glacial and interglacial stages reveal important information on the paleoclimate of eurasia and the history of ice cover and drift patterns in the arctic ocean. this study focuses on the sediment transport of siberian rivers which drain into the laptev sea. the aims are to quantify the sediment transport and to characterise the material being transported through means of chemical and mineralogical methods. the research objectives are to distin guish material transported by different rivers and to find characteristic signatures that allow the identification of this material in the marine sediments of the laptev sea shelf and the arctic ocean. the present article concentrates on 184 v. rachold et al. hydrological characteristics of the lena basin and on the inorganic geochemistry of the suspended particulate material (spm). investigation area the lena river originates near lake baikal, crosses east siberia from south to north, and has a length of 4400km. the lena basin extends throughout almost all of east siberia (jakutia) with an area of 2.5 x 106km2. the main part of the lena basin is build up by the siberian platform, which is bordered by the baikal folded region in the south, the ochotsk tukotski volcanogenic belt in the southeast, and the verchojano-kolymean folded region in the northeast. the siberian platform is formed of plateaus, tablelands and plains. the most extensive units are the prilenskoe plateau which embraces the valley of the middle lena and the central jakutian plain including the middle lena river with the lower reaches of its tributaries-the aldan and the viljuy rivers. the prilenskoe plateau is mainly composed of limestones and limestone-terrigenic sediments. the central jakutian plain was an area of subsidence in the mesozoic consisting of terrigenic sediments of jurassic to cretaceous age as well as quaternary alluvial deposits. the olenek-viljuy tableland in the northwest is formed of triassic volcanic rocks while the aldan highland is composed of archean and proterozoic crystalline and metamorphic rocks. ranges and mountains of the baikal folded region consist of gneiss, shist, quartzite and marbleised limestone of proterozoic age. in the verchojano-kolymean folded region permian and carboneous terrigenous sediments, volcanic rocks and granitoids of triassic and jurassic age are more common. the climate in the lena basin is characterised by a long and cold winter with temperatures down to -45 to -50°c during three months and a short hot summer (up to +30 to +35"c) during two months). the average annual precipitation in the lena basin is 330 mm with 70 to 80% occurring during summer (gordeev & sidorov 1993). almost the entire basin is located within the permafrost zone. unfrozen sediments (taliks) underlie the main channel of the lena river due to warming of the large water mass. samples and methods hydrology regular hydrological measurements in this region were started between 1925 and 1935. today a sum of 340 hydrometeorological stations, which are randomly scattered over the drainage area, are in operation. at several of these stations water discharge and total spm concentrations are measured daily. the data are available through publications of the leningrad hydrometeorologi cal service. the upper and middle reaches of the lena river are relatively well explored; hydro logical data cover the last 30 to 40 years (leningrad hydrometeorological service 1987). from 1969 to 1994 the research laboratory of soil erosion and channel processes of the geographical faculty, moscow state university, investigated the hydrological and geomorpholo gical features of basins, channels, confluences and deltas of the viljuy, the aldan, the kirenga, the vitim, the lena, the omoloi and the jana rivers. the seasonal variations in spm concentrations in the lena river and its tributaries, as well as in the different channels of the lena delta, were studied from 1975 to 1981. during the ice-free periods, daily measurements were carried out. integrated water samples from the surface to the bottom were obtained by a special river water sampler. the spm was separated by pressure filtration. the concentration of total spm was calculated from the weight difference between the pure and the sediment loaded filters. the data on the annual water discharge, sediment transport and the seasonal variations presented in this study are based on daily measurements from the hydrometeorological sta tions and additional analyses of spm concentra tions carried out during expeditions between 1975 and 1981. since hydrological data from the last 30 years are available at most stations, our estimates must be regarded as long-term average values. to calculate the sediment distribution along the different channels of the lena delta, we used the water discharge data measured at the hydro meteorological station of stolb island (fig. 1) and those reported by ivanov et al. (1983). total spm concentrations of the main channels between stolb island and the mouths were analysed during the ice-free periods from 1975 to 1977. sediment transport to the laptev sea 185 fig. i . location map of the 1994 lena expedition. station numbers and positions of hydrometeorological stations are indicated. geochemistry sampling was performed during an expedition to the lena river carried out by the alfred wegener institute and the moscow state university in july and august 1994 (rachold et al. 1995). samples of surface sediments, water and spm were taken along the way from jakutsk to the lena delta with the research vessel professor makkaveev at 24 stations (fig. 1). additional samples were re trieved from the major tributaries, the aldan and the viljuy rivers. integrated water samples were obtained by a river water sampler. the water was filtered on 186 v. rachold et al. fig. 2 . annual water discharge and sediment load of rivers draining to the laptev sea. the data are based on daily measurements of hydrometeorological stations in the lower reaches of the rivers carried out during the last 30 years. the specific sediment discharge of the river basins is indicated. board the ship by vacuum filtration within hours of collection. millipore filters, pore size 0.45 pm, were used for inorganic geochemistry, and glass fiber filters (whatman gf/f), pore size 0.7 pm, for organic analyses. the filtered water volume varied between 0.5 and 2 1 depending on the total spm concentration. after freeze-drying, acid digestions of the sediment-loaded filters were performed in teflon vessels using ultrapure hn03, hc104 and hf. the residues were redissolved in hn03 and diluted with h 2 0 to a final volume of 20 to 50 ml depending on the sediment concentration. major elements al, ti, fe, mn, mg, ca, na, and k were analysed by icp-oes, trace elements and rare earth elements by icp-ms. glass fiber filters were pulverised in an achat pestle. c,-n-, sconcentrations were analysed by ir-absorption (c and s) and temperature con ductivity (n) by a leco element analyser. d13c values of the particulate organic material (pom) were measured by a finigan mat delta s mass spectrometer. accuracy of the analytical data was checked by international standard reference ma terial for every method. results and discussion hydrology average annual water discharge and sediment load of the major rivers draining to the laptev sea sediment transport to the laptev sea 187 fig. 3. seasonal variations in water discharge and sediment transport of the lower lena river. daily water discharge (lo3 m3 per second, left axis) and daily sediment transport (lo6 tons per day, right axis) are presented. the data recorded at the hydrometeorological station kjusjur (leningrad hydrometeorological service 1987) during 1983 to 1985 represent the typical seasonal pattern. 3u are presented in fig. 2. the estimates for the lena river (520 km3 x 6' and 21 x lo6 t x a-') are based on daily water discharge data and total spm concentrations measured at the lowest hydro meteorological station kjusjur (145 km south of the delta, fig. 1) during the last 30 years (leningrad hydrometeorological service 1987). values for the other rivers are calculated from water discharge data and spm concentrations presented by the hydrometeorological stations in the lower reaches of those rivers. the total annual water discharge and sediment transport to the laptev sea calculated on the basis of these values accounts for ca. 700 km3 and ca. 27 x lo6 tons, respectively. the specific sediment discharge of the river basins varies between 5 and 100 tons per km2. the lowest values can be observed in the chatanga and anabar basins (fig. 2). rivers draining to the laptev sea are generally char acterised by significantly lower specific sediment discharge than for example the ob river with 100 to 200 tons per km2 (snischenko 1992). rivers of the lena basin are characterised by the typical east-siberian water regime. the main features are long and high, ridge-like summer floods and very low water flow in winter. this is a reflection of the sources and behaviour of water supply. for the lower lena, 50% of the water is formed from snow melting, 35% from rain and 15% from groundwater. about 75 to 95% of the water discharge occurs during warm seasons. the maximum can take place both in spring and summer depending on latitude and altitude of the sub-basin. for the lena itself, the maximum flow appears in april in the upper reaches, in may in the middle reaches and in june in the lower reaches. average water discharge data measured at the hydrometeorological station kjusjur from 1983 to 1985, which represents the typical pattern for the lower lena river, are presented in fig. 3. the variability of sediment concentration from season to season is very pronounced. sediment concentration amounts to 60 to 80mgil during spring flood and falls to 5 mgil and lower in winter. summer rain floods only result in an increase of turbidity up to 20 to 40mgil, so that the main portion of the sediment load of the lena is transported during spring floods (at kjusjur more than 50% during one month). the daily sediment transport calculated from the water discharge data and total spm concentrations is presented in fig. 3. the downstream accretion of the water mass and sediment load in the lena river is not uniform. the lena confluences twice with tributaries having water discharges comparable to that of the main river, the vitim and the aldan rivers. according to the position of these tributaries, the lena is traditionally subdivided into the upper reach (upstream the vitim), the middle reach (from the vitim to the aldan) and the lower reach (downstream of the aldan). the aldan supplies 35% of the lena discharge, the 188 k rachold et al. kjusjur zmeinovka soljanka jakutsk (tabaga) iigansk profile of water suflace 100 i 0i i 3500 3000 2500 2000 1500 1000 500 0 distance from the laptev sea (km) fig. 4. downstream accretion of water discharge (left axis) and sediment load (right axis) along the channel of the lena river. average data of the last 30 years recorded at hydrometeorological stations and total spm concentrations measured during 1975 to 1981 form the hasis of the calculated values. the profile of the water surface is indicated at the bottom. vitim 20%, the olekma 15%, and the single important west tributary-the viljuy-not more than 10%. the sediment discharge of the lena river increases approximately proportionally with water discharge (from 0.1 x lo6 tons per year at kaeug to 9.9 x lo6 tons at tabaga, and 21 x lo6 tons at kjusjur). fig. 4 shows the profile of the water surface, water discharge and sediment load along the lena river. the data were calculated from total spm concentrations analysed during 1975 to 1981 and daily water discharge data as well as spm concentrations reported by the hydrometeorological stations. human influence on the sediment load in the lena basin is connected with mining industry. because systematic monitoring of sediment load began at the same time or later than mining, however, it is difficult to determine the natural background of river turbidity. in the tributaries of the vitim river, gold exploration started at the end of the 19 century, and regular monitoring of the sediment load was initiated in 1930. the regular channel dredging of the lena river and its main tributaries to maintain navigation is another source of technogenic sediments. dred ging resuspends fine particles and activates bottom load movement. the mining of the channel alluvium for construction purposes has the same effect. for example, near the city of jakutsk the volume of channel dredging was 4 x lo6 tons per year, and 2 x lo6 tons of sediments were removed from the channel. this is almost comparable with the natural sediment transport, which is about 8 x 106 tons at this place (zaitsev & calov 1989). the distribution of water and sediment dis charge along the different branches of the lena delta controls the sediment transport to the laptev sea (korotaev 1984; korotaev et al. 1990). fig. 5 shows a schematic map of the lena delta and the water and sediment discharge of the main channels. according to data of the hydro meteorological station near stolb island, the bykovskaja channel receives 25%, the trofimovs kaja channel 61%, the tumatskaja channel 7% and the olenekskaja channel 7% of the annual water volume. however, only a minor portion of the water discharge is transferred to the laptev sea through the main channels of the delta (ivanov et al. 1983). in the eastern main delta branch, the bykovskaja channel, water discharge gradually decreases along the main channel. only sediment transport to the laptev sea 189 a l a p t e v s e a fig. 5. schematic map of the lena delta. water and sediment discharge along the main delta branches are displayed. initial water discharge data at the beginning of the main channels were measured at the hydrometeorological station stolb island. the data on water outflow to the laptev sea are taken from ivanov et al. (1983). sediment load of the different channels was calculated from those water discharge data and measurements of the concentration of spm along the main channels. 100 krn l i ? i 06 tons a i water discharge: 520 km3 per year 100% i sediment load: 21.106 tons per year about 30% of the initial discharge reaches the sea through the main channel. the hydrographical network of the trofimovskaja and the sardachs kaja channels have complicated structures and contain several different regional sub-delta sys tems. therefore the changes in water discharge along these channels are very pronounced. only 7 to 8% of the initial water volume reach the mouth barr of the trofimovskaja channel. the opposite situation in water discharge dynamics charac terises the western delta branch-the olenekskaja channel. its water discharge does not exhibit significant changes along the 145 km of channel length. based on those water discharge data and total spm concentrations measured along the main channels of the lena delta, the annual sediment transport through the main channels can be calculated. the results are presented in fig. 5. the annual sediment transport through the trofimovskaja channel does not exceed 0.4 to 0.8 x lo6 tons. the sediment transport of the 190 v . rachold et al. table 1. chemical composition of spm of the lena river and its major tributaries. station a i a ti02 -0. mno mu0 coo na,o &o c 6 s bi cd co cr cs cu go hi u mo nb ni pb rb 1 2 3 4 6 7 8 10 11 12 13 14 15 18 17 18 20 21 12.86 0.605 13.68 0.626 14.06 0.614 13.83 0.621 13.22 0.684 15.79 0.662 15.43 0.682 14.55 0.669 14.76 0.684 15.85 0.709 15.62 0.729 11.43 0.457 14.21 0.664 15.02 0.712 14.43 0.691 15.62 0.752 14.81 0.639 14.35 0.689 5.26 0 185 5.63 0.207 5.84 0.122 5.51 0.151 4.49 0.169 6.05 0.117 5.61 0.128 5.47 0.115 5.43 0.128 6.25 0.141 6.18 0.155 3.32 0.075 5.43 0.150 6.16 0.220 6.07 0.232 6.72 0.271 6.19 0.272 5.53 0.161 2.93 3.70 2.15 2.53 5.15 747 0.40 0.98 18.0 76 3.63 83 17.0 3.04 36 1.79 12.1 75 673 99 2.87 3.44 1.96 2.57 8.83 892 0.80 6.65 18.9 80 3.88 338 18.6 3.04 41 1.96 11.9 170 1539 100 2.17 2.12 1.79 2.77 1.03 742 0.75 1.99 15.3 w 4.79 102 17.9 3.39 41 1.37 11.4 69 1513 99 2.27 2.33 2.07 2.79 4.08 709 0.33 0.97 16.8 56 4.83 92 18.7 3.57 42 1.74 12.5 74 576 105 1.49 1.97 1.37 2.80 4.12 752 0.35 4.94 18.4 55 2.63 161 16.3 3.43 25 1.03 10.4 145 914 87 1.83 0.84 1.90 3.09 3.09 784 0.26 1.15 16.0 62 7.00 67 21.9 4.43 43 1.66 14.4 46 47 129 1.90 1.24 2.00 3.07 2.84 762 0.24 0.86 16.3 60 6.25 94 21.4 4.03 42 1.56 15.2 59 79 126 1.94 1.50 1.98 3.11 3.14 759 0.24 3.71 15.3 62 5.82 53 202 3.92 41 1.33 13.1 54 52 115 2.19 2.21 1.96 2.79 2.52 738 0.21 0.77 17.1 58 4.58 80 20.2 3.69 40 0.94 12.9 59 33 110 2.09 1.27 1.99 3.12 3.05 791 0.24 0.73 17.6 61 6.49 50 22.2 4.31 48 1.63 14.5 50 56 126 2.14 1.64 2.25 2.97 3.27 727 0.26 0.76 17.4 60 5.69 57 21.2 4.09 48 1.38 13.7 48 41 114 1.31 1.50 1.98 2.50 3.03 694 0.11 0.31 11.4 38 2.73 24 15.5 2.61 27 0.55 10.4 26 19 94 2.08 1.93 2.02 2.66 3.88 703 0.22 0.90 17.9 62 4.49 126 20.2 3.63 41 1.03 13.6 88 83 103 2.20 1.89 2.15 2.86 4.26 723 0.18 0.80 17.8 59 4.47 121 21.0 3.77 43 1.02 12.6 71 70 98 2.13 1.90 2.11 2.78 4.40 760 0.23 3.30 19.4 75 5.00 207 22.2 3.90 43 1.74 14.8 135 84 126 2.36 2.03 2.07 2.86 5.14 814 0.25 1.54 20.7 86 5.46 135 23.6 4.13 48 1.79 14.7 116 229 134 2.05 l.m) 2.22 3.03 5.73 801 0.29 7.50 20.1 91 5.72 226 22.8 3.60 48 2.21 13.7 133 356 134 2.13 183 2.18 2.69 3.73 728 0.21 0.74 17.1 76 4.99 102 20.2 3.64 45 097 12.9 60 154 107 22 12.64 0.589 4.69 0,134 1.94 1.97 2.10 2.54 4.49 621 0.41 0.74 15.5 67 3.97 143 17.7 3.27 36 0.89 12.1 62 76 98 swlon 1 2 3 4 6 7 8 10 i1 12 13 14 sb sn sr to th ti u v w v ln lr la i% pr nd sm eu qd tb dy ho er tm vb lu 0.85 336 274 0.77 13.8 0.52 4.01 83 1.61 23.2 365 98 47.1 97 10.7 39.7 6.94 1.45 6.58 0.85 4.84 0.84 2.63 0.26 2.52 0.32 2.70 862 266 0.66 14.4 0.58 4.43 101 1.62 22.8 1019 96 536 114 12.3 44.6 7.74 1.w 7.16 0.88 4.80 0.90 2.68 0.35 2.46 034 2.28 1083 162 0.62 10.0 0.61 2.91 104 156 20.4 573 1 1 1 35.0 77 8.2 30.6 5.92 1.24 544 0.73 4.09 0.81 2.30 0.32 2.32 0.33 0.95 186 187 0.91 13.7 0.60 3.45 92 1.60 21.6 324 118 43.9 96 10.3 38.0 6.78 1.48 6.25 0.80 4.42 0.83 2.45 0.34 2.45 0.34 2.46 460 209 0.73 7.3 0.46 1.93 83 1.08 16.8 533 115 294 65 6.9 25.1 4.83 1.26 4.32 0.59 3.39 0.66 1.88 026 192 0.26 0.75 5 135 1.01 12.9 0.67 3.49 126 1.54 24.9 343 158 41.7 92 98 35.3 6.60 1.50 6.33 0.87 4.91 0.97 2.90 0.40 2 8 4 040 0.62 15 150 1.05 13.0 0.65 3.56 108 1.53 24.2 306 150 44.4 96 10.3 37.3 6.70 1.53 6.34 0.89 4.82 0.91 2.71 0.39 2.75 0.38 0.79 6 159 1-01 12.2 0.66 3.08 90 1.51 22.8 399 137 43.3 94 10.0 36.8 6.62 1.47 6.13 0.81 4.59 0.90 2.66) 0.37 2.71 0.36 0.42 7 217 0.87 11.5 0.58 3.03 90 1.41 22.0 381 129 43.7 94 10.1 36.5 6.71 1.52 6.13 0.79 4.53 0.85 2.50 0.33 2.48 0.33 0.71 7 159 1.01 12.4 0.68 3.25 96 1.58 24.6 329 149 42.3 92 9.8 35.9 6.67 1.53 6.16 0.84 4.86 0.94 271 040 2.86 0.40 0.60 4 187 0.93 120 0.66 2.90 116 1.60 23.8 321 138 43.7 94 10.0 37.2 6.73 1.49 6.34 0.82 4.67 0.92 2.62 0.36 2.86 0.36 027 3 221 0.60 7.1 0.47 2.m) 58 0.94 15.5 144 100 29.1 64 6.8 24.8 4.46 1.15 4.18 0.55 3.00 0.57 1.68 0.23 1.66 024 15 0.50 43 219 0.70 11.5 0.55 2.92, 104 1.54 22.4 356 132 43.7 95 10.0 36.5 6.63 1.51 6.19 0.80 4.39 0.63 2.41 0.33 2.40 0.33 16 0.68 2u 202 0.86 11.5 0.42 2.92 98 1.44 22.6 394 122 42.5 96 10.1 36.9 6.46 1.48 6.15 0.82 4.53 0.84 2.58 0.25 2.43 0.27 17 1.01 11 192 1.02 12.8 0.49 3.29 113 1.65 25.2 696 130 48.0 110 11.6 42.8 760 1.74 7.15 0.96 5.09 0.95 2.88 0.33 2.73 0.33 18 1.02 17 202 1.04 13.5 0.50 3.52 id8 1.65 25.5 490 137 52.1 116 12.2 44.0 7.62 1.78 7.23 0.97 5.20 1.00 2.63 0.29 2.73 034 20 1.33 41 179 0.72 13.2 0.54 3.44 i29 1.71 26.3 1020 127 54.0 124 12.8 45.4 7.44 1.67 7.71 0.95 5.14 0.98 2.93 032 2.60 0.31 2l 0.88 31 191 0.88 11.8 0.47 3.07 93 1.47 21.6 536 129 43.3 97 10.3 36.6 6.57 1.57 6.26 0.81 4.27 0.81 2.51 0.28 2.33 0.28 22 0.54 20 167 0.74 10.6 0.43 2.75 102 ,138 19.8 480 108 40.2 88 9.3 34.3 6.06 1.36 5.92 0.74 3.94 0.72 2.23 0.24 2.04 0.23 major elements [wi. %i tram elemenls [manrgl bykovskaja channel is 1.0 to 1.3 x lo6 tons per year, that of the olenekskaja channel varies from 0.7 to 1.1 x lo6 tons per year. there are no data available of the tumatskaja and sardachskaja channels. with the present data set we cannot provide a complete picture of the sediment distribution within the lena delta. however, it can be stated that from 21 x lo6 tons of spm coming into the sub-delta section (at kjusjur), only 2.1 to 3.5 x lo6 tons (10 to 17% of this value) reach the shore of the laptev sea through the main channels of the delta (fig. 5). the major portion of the sediment is dispersed in vast delta plains and second order distributors. geochemistry of the suspended particulate material during our sampling in july 1994, the sediment concentration varied between 10 mg/l and more than 100 mg/l, with high values between zigansk and kjusjur and low values near jakutsk and in the delta. the average sediment concentration of 40 mg/l is in general agreement with the typical sediment transport to the laptev sea 191 v. rachold et al. 192 15 10 8 2 jakutsk bykovskij , n 1 5 0 0 cu/ai 100 0 200 400 600 800 1000 1200 1400 1600 distance from jakutsk (km) summer values of the last years measured at the hydrometeorological stations. the major and minor element composition of the spm sampled between jakutsk and the lena delta is presented in table 1 and fig. 6. the values of average shale (wedepohl 1971, 1991) and upper continental crust (taylor & mclennan 1985) are shown for comparison. to compensate for different amounts of organic material diluting the mineral fraction, aluminum normalisation was applied. aluminum is a conservative element and exclusively bound to the mineral component. the carbon concentration analysed from glass fiber filters varies between 1 and 9%. the d13c values of the organic fraction are almost constant throughout the river with an average of -27.0 i: 0.8%0, indicating the dominance of c3 plants. very similar values (-26.7 2 0.4%) have been analysed in the congo river spm (mariotti et al. 1991). the elemental composition of the lena river spm is very homogenous for all of the major elements. the median values of the al normalised concentrations compare well with average shale. the upper continental crust composition on the other hand displays significant differences (fig. in general, average shale can be regarded as the weathering product of the upper continental crust after subtracting the “soluble” elements. for this reason average shale is characterised by a depletion in na and ca and an enrichment in fe 6). d s1 5 . 0 . c e fig. 7. al normalised cu and zn (y-axis, right side) concentrations and carbon content (y-axis, left side) of particulate material of the lena river. the figure displays a long section of the lena river between jakutsk and cape bykovskij in the lena delta. the scale on the x-axis corresponds to the distance of the station from jakutsk in h. the main tributaries the aldan and the viljuy rivers are shown. and ti compared to the upper crust. the correspondence of the median composition of the lena river spm and that of average shale therefore suggests that (1) the average major element composition of all lithologies in the lena basin is comparable to that of the upper continental crust, and (2) that the rate of chemical weathering in the drainage area is similar to the world-wide average. as the lena river drains a large basin, the agreement of the average composition of the rocks in this area and the upper crust is not surprising. the same holds true for other major rivers (gaillardet et al. 1995). the chemical data of the lena river spm analysed in the present study do not reflect the reduced denudation rate reported for polar regions (ugolini 1986). in the lena basin weathering processes should be furthermore decelerated because of scarce precipitation. gordeev & sidorov (1993) reported that the annual chemical denudation rate in the lena basin is about half of the world average. however, to study weathering processes in detail, which is not the purpose of this study, data on the dissolved load are essential. most of the trace elements show a similar behaviour. in particular the aluminum normalised concentrations of co, cr, ga, mo, nb, rb, sb, th, t1, u, v, w and zr are constant throughout the river and the median values are similar to that of average shale. however, some differences are visible: (1) al sediment transport to the laptev sea 193 amazon 0 mississippi a lndus fig. 8. shale normalised ree pattern of the lena river and other major rivers. data for amazon, mississippi, indus and ohio have been oresented 0.5 by goldstein and jacobsen i (1988). shale data (north american shale composite = nasc) are taken from condie (1993). i i i 1 1 1 1 1 1 1 1 i i i i la ce pr nd sm eu gd tb dy ho er tm yb lu ree normalised ba, cs, and hf concentrations are also constant but ba and cs concentrations are higher and hf concentrations are lower than that of average shale and upper continental crust; (2) cd, cu, pb, sn and zn display a strong scatter with high values in some samples. for the elements ba, cs and hf, the differences can be interpreted by deviations of the average source rock concentration in the lena basin from that of average shale. high cd, cu, pb, sn and zn concentrations on the other hand cannot be explained by the lithology of the drainage area. fig. 7 displays the carbon content and the al normalised concentrations of cu and zn analysed along the lena river between jakutsk and cape bykovskij in the lena delta. note that the scale on the x-axis is the distance of the station form jakutsk in km. the positions of the aldan and the viljuy data points correspond to the distances of their mouths from jakutsk. a correlation between carbon content and cu, zn and cd concentrations can be observed. obviously the concentrations of these elements in the particulate material are linked to absorption to organic material. dai et al. (1995) pointed out that in river water cd, cu and ni are associated with colloidal organic carbon. the elements pb and sn are highly correlated and exhibit high values in the area of jakutsk including the aldan and the viljuy rivers. bi and sb show a similar but less pronounced behaviour. the enrichment of these trace metals in the particulate material cannot be explained at the moment. the association of bi, pb, sb and sn suggests pollution from mining. however, there are no ore deposits in this area, and cassiterite only occurs in the jana basin. the composition of the spm of the aldan river, which is the major tributary of the lena river, does not exhibit strong deviations from that of the lena river because the aldan river drains very similar lithologies. for most of the major and minor elements the differences do not exceed the variations within the lena river itself. the viljuy river particulate material on the other hand can be clearly distinguished from that of the lena river. the ti/al ratios of the viljuy river are higher and the fe/al ratios evidently lower than that of the lena river: lena river: ti/ al = 0.052 t 0.002, fe/al = 0.518 z 0.040 (n = 17); viljuy river: ti/al = 0.059, fe/al = 0.448 (n = 1). furthermore, the spm of the viljuy river can be distinguished from that of the lena river by most of the trace elements. while the normalised concentrations of cs, li, rb, th, u, w and y are lower, the concentration of co is higher than that of the lena river spm. fig. 8 displays ree patterns of the spm of the lena river and some other major rivers. the concentrations are normalised to the north american shale composite (nasc, condie 1993). the ree pattern of the lena river spm 194 v. rachold et al. jakutsk bykovskij 1.3 1.25 1.2 1.15 1.1 1.05 1 0.95 0 200 400 600 800 1000 1200 1400 1600 distance from jakutsk (krn) material proves to be very similar to that of other major rivers, which are generally characterised by a slight enrichment of the lree and a deficiency of the hree (martin et al. 1976; goldstein & jacobsen 1988). the lena river spm, for example, displays almost the same distribution as that of the mississippi river. the ree patterns of river spm are sensitive to the drainage basin geology (goldstein & jacobsen 1988). however, if the drainage basin is large enough the ree pattern of the spm represents the weathered upper continental crust. for that reason the spm of major rivers display similar ree patterns. as has been pointed out earlier, the viljuy river shows some differences. eu and ce anomalies of the particulate material are displayed in fig. 9. the figure shows a long section of the lena river including the aldan and the viljuy rivers. while the lena and the aldan rivers are characterised by the absence of any ce and eu anomalies, the viljuy river spm exhibits a pronounced positive eu anomaly (fig. 9). the catchment area of the upper viljuy river consists of triassic volcanic rocks. the series is mainly formed from basaltic tuffs and tuffitic rocks as well as trap basalts. due to the magmatic fractionation of ca rich feldspars upper continen tal crust and average shale are characterised by a negative eu anomaly relative to the primitive earth mantle or chondrite, respectively. continen fig. 9. eu and ce anomalies in the spm of the lena river (long section between jakutsk and bykovskij in the lena delta) and its main tributaries the aldan and the viljuy rivers. see text for explanation. tal flood basalts on the other hand do not exhibit this pronounced eu anomaly since they are less fractionated. therefore the average shale normal ised ree patterns of material derived from basaltic rocks displays a positive eu anomaly. chemical data of siberian trap basalts from the noril’sk district have been published by lightfoot et al. (1993). these basalts are located west of the viljuy catchment area but belong to the same sequence like the basaltic rocks in the viljuy basin. the nasc normalised ree distribution of the noril’sk trap basalts displays eu anomalies of t1.3 to t1.5. the positive eu anomaly of the spm of the viljuy river accounting for 1.25 reflects the influence of the trap basalts (fig. 9). conclusions the material transport of the siberian rivers mainly by the lena river strongly influences the sedimentation in the laptev sea shelf and the arctic ocean. due to the climatic situation in the drainage area, the main portion of the material is transported during spring flood. however, it has to be taken into account that only 10-17% of the material entering the lena delta reach the laptev sea through the main branches while the rest is dispersed in the delta. it is difficult to determine the quantity of sediment transport to the laptev sea 195 natural sediment transport of the lena river because systematic hydrological monitoring in jakutia began at the same time as mining. additional sediment is transported due to channel dredging for navigation purposes. near the city of jakutsk the volume of dredging almost equals the natural sediment transport. the spm of the lena river shows a uniform major element composition that generally com pares well with that of average shale. this also holds true for most of the trace elements with the exceptions cd, cu and zn. these elements are obviously associated with the organic fraction. high concentrations of pb and sn in the area of jakutsk cannot be explained at this moment. since average shale can be regarded as the weathering product of the upper continental crust after dissolution of “soluble” elements, we con clude that the average composition of the rocks in the lena basin is similar to that of the upper continental crust. furthermore our data reflect the influence of chemical weathering on the spm composition. while the chemical composition of the spm of the aldan river is similar to that of the lena river, the viljuy river can be clearly distin guished. in particular the ree pattern of the spm of the viljuy is characterised by a positive eu anomaly relative to average shale resulting from the occurrence of basaltic rocks in the catchment area. rivers which drain a large basin in the order of lo6 km2, as does the lena river, integrate a variety of lithologies. for that reason the spm of the lena river does not exhibit specific geo chemical signals. in contrast, the spm of smaller rivers such as the viljuy river clearly reflects the geology of the more restricted drainage area and displays typical chemical signatures. further analyses are required to obtain more information about the material transport by siberian rivers to the laptev sea shelf and the arctic ocean. at the moment, sr isotopic composition of the spm and heavy mineral distribution of the sediments are studied. acknowledgements. the authors wish to thank m. zimmer and e. cramer of the “geoforschungszentrm potsdam” for supporting the analytical work. special thanks to the crew of rv professor makkaveev and to 0. m. kirik. this study is part of the german-russian project “the laptev sea system” which is founded by the german ministry of education and research (bmbf) and the russian ministry of research and technology. this is publication no. 1149 of the alfred wegener institute for polar and marine research. references aagaard, k., swift, j. h. & carmack, e. c. 1985: thermohaline circulation in the arctic mediterranean seas. j. geophys. res. 90, 48334846. bischof, j., koch, j., kubisch, m., spielhagen, r. f. & thiede, j. 1990 nordic seas surface ice drift reconstructions: evidence from ice rafted coal fragments during oxygen isotope stage 6. pp. 235-251 in dowdeswell, j. a. & scourse, j. d. (eds.): glacimarine environments: processes and sediments. geological society special publ. no 53. clark, d. l. 1990 arctic ocean ice cover; geologic history and climatic significance. pp. 53-62 in grantz, a,, johnson, l. & sweeney, j. f. (eds.): the arctic ocean region. geol. soc. am., boulder, co. condie, k. c. 1993: chemical composition and evolution of the upper continental crust: contrasting results from surface samples and shales. chem. geol. 104, 1-37. dai, h., martin, j. m. & cauwet, g. 1995: the significant role of colloids in the transport and transformation of organic carbon and associated trace metals (cd, cu and ni) in the rhone delta (france). mar. chem. 51, 159-175. dethleff, d., niirnberg, d., reimnitz, e., saarso, m. & savdenko, y. p. 1993: east siberian arctic region expedition 92: the laptev sea-its significance for arctic sea-ice formation and transpolar sediment flux. rep. polar res. 120, 1-44, eggertsson, 0. 1994: driftwood as an indicator of relative changes in the influx of arctic and atlantic water into the coastal areas of svalbard. pofar res. 23, 209-218. eicken, h., viehoff, t., martin, t., kolatschek, j., alexandrov, v. & reimnitz, e. 1995: studies of clean and sediment-laden ice in the laptev sea. rep. polar res. 176, 62-70. gaillardet, j., duprc, b. & allegre, c. j. 1995: a global geochemical mass budget applied to the congo basin rivers: erosion rates and continental crust composition. geochim. cosmochim. acta 59, 3469-3485. goldstein, s. j. & jacobsen, s. b. 1988 rare earth elements in river water. earth planet. sci. lett. 89, 3 5 4 7 . gordeev, v. v. & sidorov, i. s. 1993: concentrations of major elements and their outflow into the laptev sea by the lena river. pp. 33-45 in church, t. m. & windom, h. l. (eds.): second international symposium on the biogeochemistry of model estuaries: estuarine processes in global change. marine chemistry 43, elsevier, amsterdam. ivanov, v. v., piskun, a. a,, korabel, r. a. 1983: raspredelenie stoka v glavnych protokach lenskoj delty (distribution of water discharge at the main branches of the lena delta). institut arktiki i antarktiki tom 378, 59-71, gidrometizdat, leningrad. kassens, h. & karpij, v. 1994: russian-german cooperation: the transdrifi 1 expedition to the laptev sea. reports on polar research 151, alfred wegener institute, bremerhaven. 168 pp. korotaev, v. n. 1984: formirovanie gidrografikskoj seti lensoj delty (formation of hydrographical network of the lena delta). vestnik moskovskogo universiteta 6 , 39-44. korotaev, v. n., michailov, v. n., babite, d. b., zaets, g. m. & bogomolov, a. l. 1990: gidromorfologieeskie processy, dinamika, gidrografiteskoj seti i ruslovye deformacii v delte r. leny (hydromorphological processes, dynamics of hydro graphic network, and channel deformations in the delta of the lena river). pp. 187-198 in b l o v , r. s. (ed.): zemljanye i vodnye resursy, erozionnaja z a g i t a i obespeknie sudo 196 v. rachold et al. chodstva (land and water resources, defense from erosion and channel management). moscow univ. publ. house, moscow. leningradskoe upravlenie gidrometeorologoikskoj slutby (le ningrad hydrometeorological service) 1987: resursy p o r erchnostnych rod ussr. osnovnye gedrologifeskie charakteristiki. c a s t 1, tom 16: srednjaja i nikjaja lena (data about regime and resources of surface water in the ussr, part 1. volume 16: middle and lower lena basin). leningrad. lightfoot, p. c., hawkesworth, c. j., hergt, j., naldrett, a. j., gorbakv, n. s., fedorenko, v. a. & doherty, w. 1993: remobilisation of the continental lithosphere by a mantle plume: major-, trace-element, and sr-, nd-, and pb-isotope evidence from picritic, and tholeiitic lavas of the noril’sk district, siberian trap, russia. contr. mineral. petrol. 114, mariotti, a., gabel, f., giresse, p. & kinga-mouzeo 1991: carbon isotope composition and geochemistry of particulate organic matter in the congo river (central africa): application to the study of quaternary sediments off the mouth of the river. chem. geol. 86, 345-357. martin, j. m., hogdahl, 0. & philippot, j. c. 1976: rare earth element supply to the oceans. j . geophys. res. 81, 3119-3124. milliman, i. d. & meade, r. h. 1983: world-wide delivery of river sediment to the oceans. j . geol. 91, 1-21. niimberg, d., wollenburg, i., dethleff, d., eicken, h., kassens, h., letzig, t., reimnitz, e. & thiede, j. 1994: sediments in arctic sea ice: implications for entrainment, transport and release. mar. geol. 119, 185-214. rachold, v., hemel, j. & korotaev, v. n. 1995: expedition to the lena river in julyiaugust 1994. rep. polar res. 182, 181-195. 171-188. reimnitz, e., dethleff, d. & niimberg, d. 1994: contrasts in arctic shelf sea-ice regimes and some implications: beaufort sea versus laptev sea. mar. geol. 119, 215-225. reimnitz, e., kassens, h. & eicken, h. 1995: sediment transport by laptev sea ice. rep. polar res. 176, 71-77. snischenko, b. 1992: multipurpose studies of erosion and sedimentation in the upper ob basin. pp. 405411 in: erosion and sediment transport monitoring programmes in the river basins, iahs-publ. no. 210. stein, r. & korolev, s. 1994: present and past shelf-to-basin transport. rep. polar res. 144, 87-100. taylor, s. r. & mclennan, s. m. 1985: the continental crust: its composition and evolution. blackwell, oxford. 312 pp. ugolini, j. c. 1986: processes and rates of weathering in cold and polar desert environments. pp. 193-235 in coleman, s. m. & dethier, d. p. (eds.): rates of chemical weathering of rocks and minerals. acad. press inc., orlando. wedepohl, k. h. 1971: environmental influences on the chemical composition of clays and shales. pp. 305-333 in ahrens, l. h., press, f., runcom, s. k. & urey, h. c. (eds.): physics and chemistry of the earth vol. 8. pergamon, oxford. wedepohl, k. h. 1991: the composition of the upper earth crust and the natural cycles of selected metals. metals in natural raw materials. natural resources. pp. 3-17 in merian, e. (ed.): metals and their compounds in the environment. vch-verlagsgesellschaft, weinheim, germany. wollenburg, 1. 1993: sediment transport by arctic sea ice: the recent load of lithogenic and biogenic material. reports on polar research 127, alfred wegener institute, bremerhaven. 159 pp. zaitsev, a. a. & b l o v , r. s. 1989: ruslovye processy i obespefenie sudochodnych uslovij na i. lene okolo g. jakutska (channel processes and channel management in the lena river at jakutsk city). wodnye resursy 5 , 75-80. the depositional environment of the laptev sea continental margin: preliminary results from the r/v polarstern ark ix-4 cruise d . nurnberg, d. k. futterer. f. niessen. n. n0rgaard-pedersen, c. j. schubert, r . f. spielhagen and m. wahsner niirnberg, d., fiitterer, d. k . , niessen, f.. n0rgaard-pedersen. n., schubert, c. j . , spielhagen, r . f . , wahsner, m. 1995: the depositional environment of the laptev sea continental margin: preliminary results from the r/v polarstern ark ix-4 cruise. polar research 14(1), 43-53. marine geological investigations were performed across the laptev sea continental shelf and slope, thirty sampling sites were selected covering a depth range of ca 3500 m. maximum core recovery was 9 m. parasound sub-bottom profiling was used for site surveying and provided important information on the depositional environment of the continental margin together with sedimentological and stratigraphical investigations. undisturbed horizontal layering of the sea-floor sediments is a common feature for the laptev sea shelf. there is no indication for glaciation of the broad shelf region during the last glacial, since moraine deposits are missing. however. a high number of plough marks in places points to recent to sub-recent ice-erosion which has led to an intensive sediment reworking on the shelf. several broadly incised river channels recorded near the shelf edge are related t o pleistocene drainage systems of large siberian rivers which cut into the dry shelves during the last glacial maximum and were subsequently filled during the holocene. during the last glacial we therefore suspect a significant freshwater contribution from the eurasian continent to the arctic ocean. the composition of the normally consolidated core sediments indicates a strong flux of terrigenous material, which is mainly provided by the siberian rivers. currents distributing the suspension load and sea ice are supposedly major agents transporting sediments aaoss the shelf to the central arctic deep sea basin. sediment cores from the upper and middle continental slope exhibit only minor lithological changes. bioturbated, fine-grained sediments with high organic carbon contents dominate. the presence of free hydrogen sulphide gas within the sediment column indicates that an intense decay of organic matter under reducing conditions is taking place. sedimentation rates are estimated to be ca. 50 cm/1000 years at the upper slope of the western laptev sea, being approximately 10 times higher than at the continental rise. the suboxic t o anoxic environment diminishes at deep sea sites of the western laptev sea. where sedimentation rates and influx of organic matter are reduced. d . nurnberg, d . k . futterer, f. niessen. c . j . schubert, m . wahsner, alfred wegener imtitute for polar and marine research, p . 0. box 120161, 0-27568 bremerhauen, germany; nmrgaard-pedersen. n . , spielhagen, r . f., geomar, research center for marine geosciences, wischhofstrape 1-3, 0-24148 k i d . germany. introduction approximately one third of the arctic ocean area is occupied by shallow epicontinental seas (gierloff-emden 1982; carmack 1986), the global importance of which is related to sea ice pro duction (colony & thorndike 1985) and brine formation (middtun 1985; aagaard 1988, 1989). the laptev sea is supposed to be one of the main sea-ice producing areas in the arctic where huge amounts of sediments may be incorporated and subsequently transported into the transpolar drift. the shelf edge lies between 50 and 60m water depths (holmes & creager 1974), and as far as 500 km from the continent. five large sub marine valleys. which are interpreted as sub merged extensions of the major rivers in that region (the lena and kotuy: holmes & creager 1974), cut into the gently dipping shelf plain. an irregular pattern of major shoals, which some times reach or break the sea surface, characterises the sea-floor topography. in the framework of the joint german-russian expedition arctic '93 during summer/autumn 44 d . niirnberg et al. 1993, multidisciplinary research was undertaken for the first time in the laptev sea from the coast across the outer shelf and continental slope t o the deep sea. t h e r,’v p o l a r s t e r n worked mainly on the outer shelf. the slope and in the d e e p sea (futterer 1994). t h e r,wkireyev from the arctic and antarctic research institute ( a a r i , st. pet ersburg, russia) investigated the inner shelf of the laptev sea (kassens &. karpiy 1994). t h e marine geology programme aboard r/v polar stern focused on the reconstruction of the depo sitional environment and its change through time. specific aspects addressed include (1) the spatial and temporal development of the arctic sea-ice cover during glacial/interglacial changes, (2) the varying impact of north atlantic water masses intruding into the arctic ocean via fram strait and the barents sea. and (3) t h e influence of the large siberian river systems for the terrigenous sediment supply onto the broad shelf and changes in marine productivity through time which are assumed to be reflected in the sea-floor deposits. four transects covering the entire continental slope area down to approximately 3500 m were chosen for sedimentological investigations. t h e easternmost laptev sea (transects g and h , fig. 1) was ice-free during september, allowing the survey to extend far into the d e e p sea basin. t h e western laptev sea (transects e and f) suffered from heavy ice conditions. transect e was re stricted to less than 1200m water depth. in this study we present preliminary results from ship board investigations. detailed stratigraphical. sedirnentological, geochemical and mineralogical investigations are currently in progress. methods high resolution subbottom profiling ( p a r a s o u n d ) bottom and sub-bottom reflection patterns of the uppermost sea-floor sediments received by the p a r a s o u n d sediment echosounder system (atlas electronics, bremen, germany) document sedimentary features, which can b e used to characterise sedimentary environments and their changes in space and time. t h e aims of the p a r a s o u n d profiling were (1) to select lo cations for coring, (2) to identify and interpret lateral differences in sedimentary facies along shelf-slope transects a n d between t h e barents and laptev seas, and (3) to evaluate major strati graphic features indicative of past environmental changes. in particular glacial-interglacial tran sitions. geological sampling and processing geological sampling and coring recovered undis turbed surface and near-surface samples (large box corer) a n d undisturbed, long sediment sequences (kastenlot and gravity core) for strati graphic, paleoenvironmental and sedimento fig. 1. bathymetric chart of the laptev sca indicating coring sites of expedition a r k 1x4 numbers indicate the awl number code (71 = ps2471). inset shows the location of the study area r/v polakstern the depositional emironwient of the laptell sea corrrineriml niargiri 45 logical investigations. fig. 1 shows the sampling locations. sediment cores were obtained along four transects from the shelf t o the lower con tinental slope. transects f, g and h covered the depth range from approximately 5 0 m t o 3500 m . coring operations along 'rransect e were terminated at a water depth of approximately 1200 m. t h e large box corer (gkg) recovered 25 undis turbed sediment surfaces and subsurface sedi ments (maximum depth 50 cm). t h e gravity corer (sl) was applied at 16 stations and penetrated sediment sequences with a n average length of 430 cm. maximum recovery was 908 cm. five kas tenlots (kal) recovered sediment sequences with an average sediment thickness of ca. 620 cm. maximum recovery was 800 cm. t h e sediment cores obtained were routinely photographed, described in detail and graphically displayed. sediment colours were identified according to the "munsell soil colour chart" (kollmorgen instruments corp., newburgh, usa). samples were coded by an awi-code (e.g. ps2460-3 sl). for the analysis of the coarse grain fraction, the bulk sediment of selected sediment samples was washed through a 6 3 p mesh, dried, and analysed under a binocular. for x-ray imaging, sediment slabs of ca. 0.5 cm thickness were taken continuously downcore in order to elucidate sedi mentary and biogenic structures. grain size distribution and distribution patterns of major sediment components were estimated from smear slide examinations. abundances of coccoliths could easily be determined under the microscope with crossed nicols, and could be applied as preliminary time constraints. whole core measurements of magnetic susceptibility in 2 cm intervals were applied for core correlation. the records mainly reflect the content of mag netite in the sediments investigated as the fer rimagnetic magnetite exhibits high susceptibilities in contrast to all other rock-forming minerals with weak diamagnetic o r paramagnetic character istics. a detailed description is given in nowaczyk (1991) and futterer (1992). measurements were performed with a bartington suscep tibility control unit m.s. 2 in conjunction with two different sensors. o n e for measurements of entire core segments, the other for paleomagnetic standard samples with volumes u p t o 10 cm3. dur ing the analyses, the sample within the sensor was subjected to a weak magnetic field (0.5 mt, f = 565 h z or f = 460 hz). results and discussion sediment echo-sounding p a r a s o u n d profiles reveal that the laptev shelf is characterised by a bat bottom topography (fig. 2). moraines, which would give an indication for the glacial history of this area, were not fig. 2 parasound w e 1" ... 5.0 lan profiles from the central and eastern part of the laptev sea shelf top between 77% n . 116"58'e and 77"14'n, 116"54'e bottom between 77"3o'n, 133"37'e and 77"21'n, 133"37'e horizontal and sub-horizontal layering and ice gouges (arrows) arc clearly visibte 3 5 h 46 d. nurnberg et al. observed. parasound penetration was mostly limited to a few metres locally increasing up to 20m. subsurface reflectors have mostly subparallel geometries. in places, they appear slightly deformed or "folded" (fig. 2). these subsurface reflectors often toplap against an unconformity and are overlain by a horizontal bed, mostly only a few metres thick. the latter is interpreted as late glacial and holocene deposits. with exposure of the shelf area, the unconforrnity may relate to the last glacial maximum. the fact that parasound was able to penetrate pre holocene laptev shelf deposits is taken as indi cation of the lack of an ice load during the last glacial. the top of subglacial deposits would be characterised by a strong contrast in acoustic impedance. therefore, the top of ice-consoli dated sediments is indicated by sound reflection rather than penetration. for example, during ark-ix/4. parasound penetration into pleistocene deposits was not observed on the barents shelf, where sediment consolidation due to a late pleistocene ice cap is proposed by vorren et al. (1983). even without consolidation of sedi ments by an ice sheet, laptev shelf sound pen etration into deeper strata is a surprising observation because relict permafrost from a periglacial tundra environment is expected to be present underneath holocene deposits. in such a case, permafrost would cause acoustic impedance near the sediment surface probably high enough to prevent further sound penetration. it is too early, however, to speculate on the reasons of the above observation before a detailed survey for perma frost features in seismic profiles is carried out. several incised river channels were recorded on profiles near the shelf edge (fig. 3 ) . the widths of the channels are on the order of a few kilo metres, the depths are about 10-15 m. all chan nels are filled with well-stratified sediments. these channels are presumably related to plei stocene drainage of the large siberian rivers, such as the lena and kotuy, and were cut into the shelf (e.g. holmes & creager 1974). most likely, this occurred during the last glacial when the sea level was proposed to be 120 m below that of today (chappell & shackleton 1986), and the coastline was located north of the shelf region near the present shelf/slope boundary. conse quently, considerable freshwater drainage most likely occurred during glacial times from the eura sian continent into the arctic ocean. these find ings together with the lack of moraine deposits imply that the area of investigation was not cov ered by an extended ice sheet during the last glacial as proposed by grosswald (1988). our investigations rather support the predominance of periglacial environmental conditions in the laptev sea area as suggested by dunayev & pavlidis (1988). east of severnaja zemlja and west of the new siberian islands, a large number of ice gouges have been observed at the sediment surface (order of magnitude lo3 numbers in total) (fig. 2). incisions of 1-101-11 depth are generally flanked by berms on just one or both sides. the total widths are on the order of a few tens of metres. in most cases. it appears that the sediment accumulated in the berms would fill the scars. the relatively small total width of the features compared to their total relief make them clearly distinguishable from drainage channels flanked by levee deposits. furthermore, the occurrence of ice gouges is strictly limited to a range of water depth between 30 and 90 m water, whereas erosional channels were observed at all water depths on the shelf. most ice gouges appear to be "fresh" and unfil led (fig. 2 bottom). some incisions show alter ation as indicated by their smoothed topography (e.g. fig. 2 top left). in places, the well-stratified character of subsurface sediments seems to be locally ploughed despite the presence of a pres ently flat and undisturbed sediment surface. fig 3 parasound profile showlng incised river channels (arrows) from the centre of the lapter sea near the continental slope between 77"03'n, 131"06'e and 8.5 km 77"02'n, 130"48'e the depositional environment of the lapteu sea continental margin 37 fig. 4. parasound profile from the lower part of the continental slope along transect h between 78"41'n, 132"41'e and 78"31'n, 132yl'e. the uppermost and lowermost sections are magnified in order to elucidate the thinning out of sediment la ye rs . from observations and simulations of for mation and filling of ice gouges from the alaskan beaufort sea, barnes et al. (1990) concluded that ice gouges are short-lived and filled within a few years. this interpretation is consistent with our observations in the laptev sea. it implies that ice erosion is presently an important shelf process on the laptev sea shelf. potentially inducing resus pension and lateral sediment transport over the shelf. indeed, parasound profiles indicate that, in places, subsurface reflectors underwent strong deformation (fig. 2, top). this is inter preted as a result of strong sediment reworking by ice gouging during the holocene. whether ice gouging is related to grounding icebergs. or pressure ridges, or both, is still unclear. the continental slope deposits belong to dif ferent facies. the central part of the laptev sea slope (transect g , from 77"01,9'n 126"25,4'e to 79"13,7'n 122"51,7"e) is characterised by reflec tion patterns of slumps down to water depths of ca 2000 rn, followed by channel and levee deposits to the deepest point at 3200m. channels have distinct or prolonged reflection character. some 48 d . niirnberg et al. channels show truncation of older beds. in places. thick undisturbed sections were found. they com prise subparallel reflectors which drape under lying topographies. penetration was down to 50 m sediment thickness. these well-stratified sedi ments are interpreted as levee facies, which are, in conjunction with channels, typical for submarine fans. since incised river channels of the lena drainage system were found o n the continental shelf, t h e fan facies observed below 2000 m water depth may have formed mainly during the last glacial. when the riverine transport of continental debris reached to the edge of the present slope/ shelf boundary. thick, mostly undisturbed, slope deposits were recorded along sections h and f (fig. 4). reflec ps2471-4 s l ps2473-4 kal ps2474-3 k a l ps2476-4 s l w d: 3.047 rn w d: 1.919 rn wd: 1.494 rn wd: 521 rn eoc = end of core eoc: 7 04 m fig. 5 . lithological core description of sediment cores from the laptev sea continental slope along transect f. t h e depositional environment of the laptev sea continental margin 49 tions are predominantly numerous down to about 100 m sediment depth. the deposits drape under lying topographies. distinct reflectors correlate over long distances and show a pronounced wedg ing out downslope. only in the lowest part of section h (deeper than 3000 m) was a major slump identified. sedirnentological and geophysical investigations all box core tops consist of soft brown mud. the surface deposits from the shelf and upper slope (50-1000 m) contain approximately 10-20% sand sized material. terrigenous grains (quartz, feld spar, rock fragments) predominate. ostracods, small bivalves, and calcareous and agglutinated benthic foraminifers are common, whereas plank tonic foraminifers are absent or rare. the sand content decreases significantly downslope and is less than 1% in water depths greater than 3000 m, there consisting almost entirely of planktonic foraminifers. the density of benthonic popu lations is high on the shelf and uppermost slope, but decreases significantly downslope. the uppermost, brown lithological unit of the sediment cores is thickest on the lower slope (ca. 60cm) and decreases to 3-10cm on the upper slope and shelf (fig. 5). this strongly bioturbated unit resembles the sediment surface in the box cores and apparently reflects the depth of oxy genation. on the shelf and upper slope, the under lying dark grey to black sediments mainly consist of sandy, silty clays. occasionally, thin sandy layers (turbidites) are intercalated, predomi nantly in the lower parts of the sediment cores (fig. 5 ) . the amount of coarse material (> 63 pm) slightly decreases with increasing water depth. when exposed to the atmosphere for a sufficient time ( 1 2 4 8 hours), the dark sediment changes to brownish and olive greenish colours. the sedi ments contain high amounts of organic matter (max. 2%), the main component of which is ter rigenous in origin (e.g. plant fibres) (stein & nurnberg 1995). formation of free hydrogen sul phide gas is typical in these sediments, pointing to the decay of organic matter by the activity of sulphate-reducing bacteria under reducing con ditions. early diagenetic precipitations of calcium carbonate hexahydrate (ikaite) were found in ca. 235 cm depth of core ps2460-4 from shallow wat ers (200 m). in the eastern laptev sea (transects g , h), the dark subsurface-sediments from the upper slope and outer shelf occur down to ca. 3500m water depth. sediments from the western laptev sea (transects e, f), however, are partly different. the subsurface sediments from water depths greater than 3000 m contain mostly silty clays of brownish to olive greenish colours, being sig nificantly lighter than sediments from shallower depths. free hydrogen sulphide gas is no longer present. a few well-preserved shallow marine bivalves ( y o l d i a amygdalea) were observed in cores ps2458-4 and ps2460-4 (transect h) at 40g 700 cm core depth. smear slide investigations of core ps2471-4 revealed the coccolith species e m i liania huxleyi and gephyrocapsa sp. to be present down to 400 cm core depth. maxima in abundance occur in near-surface sediments (ca. 20 cm), between ca 200cm and 300cm, and around ca 380cm (fig. 6). mixing of sediment by bioturbation is extremely strong o n the shelf and upper slope. vertical chitinous worm tubes with a length up to 30 cm indicate a very thick upper mixed sediment layer. although the degree of benthonic coverage decreases downslope, bioturbation is still an important environmental process, which prevents any stratification. fig. 6 shows magnetic susceptibility records of sediment cores from transect f (see figs. 1 and 5 ) . continental slope and shelf sediments are typically characterised by magnetic suscepti bilities of approximately 40-250 x si. these values are significantly higher than values pre viously published for central arctic ocean sedi ments. cores recovered during the arctic '91 expedition of r/v polarstern have magnetic susceptibilities of approximately 25-50 x si (amundsen and nansen basin) and 15 30 x 1o-'si (gakkel and lomonosov ridges) (futterer 1992). the magnetic susceptibilities generally decrease downslope. shelf and upper slope sedi ments (<500m water depth) are commonly characterised by magnetic susceptibilities larger than 60 x si, mainly ranging around 100 x si with extremes up to 250 x si. below ca 500 m water depth, mean magnetic sus ceptibility values decrease to 2c60 x si. the decrease of magnetic susceptibilities from shelf to continental slope and into the central arctic deep-sea and mid-ocean ridge sediments presumably reflects a constant. density-dep endant loss of heavy, ferrimagnetic minerals of c o re c o rr el at io n a cr o ss t h e l ap te v s ea c o n ti n en ta l sl o p e b y m ag n et ic s u sc ep ti b ili ty l o w er s lo p e i u p p e rs lo p e p s 2 4 7 1 -4 s l p s 2 4 7 2 -4 s l p s 2 4 7 3 -4 k a l p s 2 4 7 4 -3 k a l p s 2 4 7 5 -3 s l 79 " 09 .1 n 11 9" 47 ,6 'e 7 8 °4 0 ,1 n 11 8" 44 ,s e 77 '5 8. 6n 11 8' 34 ,s e 77 '4 02 " ll b 0 3 4 ,5 'e 77 '3 1. 8n 11 8' 27 .8 'e n a n n o p la n k to n s u s c e p t. ( 1 0 e -5 s i) 0 20 4 0 60 80 80 0 7 0 0 l . fn m a g n e ti c s u s c e p ti b il it y s u s c e p t. ( 1 0 0 -5 s i) 20 40 60 8 0 s u s c e p t. ( 1 0 8 -5 s i) s u s c ed t. (1 0 e -5 s ib s u s c e ~ t. 11 0 0 -5 s i) 20 4 0 60 80 1 0 0 1 2 0 4 0 so 12 0 1 w d 2 6 2 0 m 80 12 0 16 0 20 0 p s 2 4 7 6 -4 s l p s 2 4 7 7 -4 s l 77 '2 3. 4n 1 1 8 °1 1 ,6 e 7 7 v 4 .6 n 11 8' 32 ,9 e lo o 15 0 2 si 100 200 400 a 500 ;i 3 800 700 800 d ec re as in g d o w n co re o xi da tio n _ _ _ _ . c in cr ea si n g a bu nd an ce in p la nk to ni c fo ra m in ife rs i t1 t3 t u rb ld it e s e q u e n c e s s e d im e n t e n ri c h e d i n o rg a n ic 0 d a rk g ra y t o b la c k f in e -g ra in e d m a te ri a l b m w n to o li v e f in e -g ra in e d s e d im e n t z o n e o f o x id a ti o n fi g. 6 . g eo ph ys ic al , se di m en to lo gi ca l an d st ra ti gr ap hi c re su lt s fr om t ra ns ec t f c ov er in g a de pt h ra ng e of ca . 4o oo m . sc he m at ic l it ho lo gy l og s, t he a bu nd an ce o f pl an kt on ic fo ra m in if er s a nd c oc co li th s an d th e de pt hs o f th e ox id at io n zo ne a re i nd ic at ed . c or e co rr el at io n (s ha de d ar ea s) is b as ed o n m ag ne ti c su sc ep ti bi li ty r ec or ds . w d = w at er d ep th the depositional environinent of the laptev sea continental margin 51 terrigenous origin (e.g. magnetite) during long range sediment transport. depositional environment the geophysical and geological investigations allow a preliminary characterisation of the outer laptev sea depositional environment. in general, the sediment composition indicates a strong supply of terrigenous material from the continent to the laptev sea shelf edge. the relatively high content of plant fragments and the occurrence of freshwater and shallow marine bivalves in cores from the middle and lower continental slope underline the importance of a large-scale downslope transport of sediments. most of the fine-grained material is probably transported in suspension by currents. the lena river, with an outflow of approximately 520 km’/ year (aagaard & carmack 1989), is one of the largest river systems flowing into the arctic ocean. the kotuy river adds another 105 km3/ year (aagaard & carmack 1989). the lena sus pension load is calculated t o amount to 17.6 mil lion tons/year (gordeev & sidorov 1993), which is relatively low compared to the 100 million tons/ year of the mckenzie river (milliman & meade 1983). significant amounts of sediment may also be contributed by sea ice. dethleff et al. (1993) and nurnberg et al. (1994) already demonstrated the importance of the laptev sea for arctic sea ice formation and resuspended sediment entrainment by sea ice. dethleff (1995) estimates the amount of sea-ice sediments exported from the laptev sea shelf to approximately 10 million tons/year. whether the entrained portion of shal low marine sediments in sea ice is subsequently released and adds to the slope sedimentation will remain unclear as long as the lack of strati graphical information prevents accurate estimates of sediment mass balances in this area. it is, however, probable that major portions of these sediments leave the laptev sea area within the transpolar ice drift (nurnberg et al. 1994). sedi ment-rafting by glacier ice seems to be of minor importance in the laptev sea. core-top sedi ments and sediment cores from the continental slope contain only minor portions of coarse sand and gravel, which may be indicative of iceberg transport. the typical black spots colouring the subsurface sediments dark grey to black are related to iron and manganese precipitations, which must be attributed to the decay of marine organic matter by the activity of sulphate-reducing bacteria (e.g. emelyanov et al. 1982). this process is active o n l y under reducing conditions. the strong anaerobic bacterial activity (in futterer 1994) indicates a rapid burial of high amounts of marine organic matter before a sufficient oxidation from sea water could take place. this process apparently is less important for the western laptev sea deep sites, where brownish and olive greenish colours indicate a “normal” deep-sea oxidation and/or a lower supply of marine organic matter to this area. here, the sediment colour is presumably determined by iron and manganese oxides, clay minerals, etc. though most laptev sea continental slope cores only exhibit insignificant lithological changes, thus preventing visual core correlation, the magnetic susceptibility provides an excellent tool for core correlation and for determination of relative sedimentation rates across the continental slope. transect f (fig. 6) comprising 7 magnetic susceptibility logs elucidates the depositional pat tern along the continental slope. the sus ceptibility record from core ps2471-4 (3047 m water depth) unambiguously correlates with all cores located on shallower slope positions. a distinct susceptibility peak at ca. 50 cm core depth in core ps2471-4 is present in all other cores from transect f , but becomes increasingly pronounced when reaching the upper slope at 187m water depth (indicated by light shading in fig. 6). here. this peak appears at approximately 560 cm core depth in core ps2477-4, indicating that sedi mentation rates apparently are approximately 10 times higher near the shelf break than in the deep sea. the continuous downslope wedging-out of the approximately 6 m thick homogenous sedi ment package from the shelf break is supported by the parasound echo-sounding profile along transect h (fig. 4). the strongly decreasing sediment accumulation with greater water depths is also suggested from the increasing amount of planktonic foraminifers in the coarse fraction of the surface sediments (fig. 6). although conditions for planktonic life become unfavourable to the north due to per ennial sea ice and colder waters, the downslope decreasing dilution of terrigeneous material makes planktonic foraminifers become the dom inant coarse fraction component in surface sedi ments from the lower slope, whereas they are rare in upper slope deposits. 52 d. nurnberg et al. fig 7. map of the siberian arctic showing glaciation models from grosswald (1988) and dunayev & pavlidis (1988). assuming a holocene age for the upper ca. 50 cm of core ps2471-4 based o n the abundance maximum of gephyrocapsa sp., which has proven to be a useful indicator for arctic interglacial sediments ( g a r d 1988). we speculate from the core correlation presented in fig. 6 that the upper approximately 6 m of sediments in cores ps2476 4 and ps2477-4 were entirely deposited during holocene times. corresponding sedimentation rates of ca. 50cm/1000 years a r e in accordance with rates of 40 cm/1000 years calculated from a radiometrically dated sediment core from the laptev sea shelf (kassens, pers. corn. 1994). the homogeneity of the sediments suggest that environmental conditions did not change sig nificantly during this time interval. t h e cores from the lower slope, which often contain sandy layers, presumably span over a longer time interval. possibly several glacial-inter glacial cycles. t h e occurrence of the coccolith gephyrocapsa sp. at 2 0 g 3 0 0 c m in the lower slope core 2471-4 (fig. 6) might be related to the last interglacial (oxygen isotope stage 5). conclusions the sedimentary environment of the laptev sea continental margin is characterised by com paratively high bulk sedimentation rates. t h e deposition of relatively high amounts of ter rigenous and marine organic matter a n d , in many areas, bacterial activity and insufficient oxidation lead to t h e presence of hydrogen sulphide gas within the dark grey t o black sediments. since there is n o major change either in lith ology or in reflection geometry, it is speculated that these deposits are of holocene age. a pre liminary coccolith stratigraphy, in combination with the magnetic susceptibility records allowing the correlation of cores across the entire slope, support this assumption. high sedimentation rates near the shelf edge, which are presumably caused by a strong lateral transport of debris on the shelf in a n off-shore direction, decrease with increasing water depth. downslope wedging-out of undisturbed sediment layers, slumps, and fan deposits o n the lower slope a r e typical for pro grading slopes. whether progradation is still active today is questionable since (1) t h e large lena delta shoreline is generally retreating ( z e n kovitch 1985) and (2) the present suspension load of the l e n a river is relatively low (gordeev & sidorov 1993). important changes affecting t h e relationship between continental supply and destructive marine forces may have occurred dur ing postglacial time. t h e lack of moraines and diamictons and of the depositional environment of the laptev sea continental inargin 53 considerable amounts of dropstones on the outer shelf do not support the assumption of a glaciated laptev sea shelf during the last glacial. an unglaciated laptev sea shelf is also supported by the incised river channels observed on the outer shelf, which were cut into the exposed shelf in late pleistocene times. a continuous freshwater supply into the arctic ocean during the last glacial under presumably periglacial conditions as suggested by dunayev & pavlidis (1988) (fig. 7) is more in agreement with our observations. the post-glacial environment is generally charac terised by ice-erosion and sediment reworking as indicated by significant numbers of ice-gouges. acknowledgements. for data discussion we thank e . reimnitz. r . stein, h. eicken, and h. kassens. thanks are also due to two reviewers, who improved the manuscript. n. n.-p. and r . f. s . were financially supported by the bmft “palloklimaprojekt”. this is contribution no. 910 of the alfred wegener institute for polar and marine research. references aagaard, k. 1988: some thoughts on the large-scale circulation of the arctic ocean. second conf. polar meteorol. oceanogr. march29-31,1988,1-3. am. meteorol. soc., madison, wisc. aagaard, k. 1989: a synthesis of the arctic ocean circulation. rapp. p. u. reun. cons. int. explor. mer. 188, 11-22. aagaard, k. & carmack. e. c. 1989: the role of sea ice and other fresh water in the arctic circulation. j . geophys. res. 94 (cio), 14485-14498. barnes, p. w., hunter, r . e . , lee. a , , reimnitz. e . & weber. w. s . 1990: sediment transport by ice gouging: application of model experiments to the arctic continental shelf. pp. 10% 111 in ackley, s. f. & weeks, w. f. (eds.): sea ice properties and processes. crrel monograph 9&1, cold regions research and engineering laboratory, hanover, new hampshire. carmack, e . c. 1986: circulation and mixing in ice-covered waters. pp. 641-712 in untersteiner n. (ed.): the geophysics of sea ice. nato as1 series b 146. chappell, j . & shackleton, n. j. 1986: oxygen isotopes and sea level. nature 324, 137-140. colony. r. & thorndike, s . 1985: sea ice movement as a drunkard’s walk. j . geophys. res. 90 ( c l ) . 965-974. dethleff, d . 1995: die laptevsee eine schlusselregion fur den fremdstoffeintrag in das arktische meereis. unpubl. ph.d. thesis. univ. kiel. 111 pp. dethleff, d . , numberg. d . , reimnitz, e . , saarso, m. & sav chenko, y. p. 1993: east siberian arctic region expedition ’92: the laptev sea its significance for arctic sea ice formation and transpolar sediment flux. ber polarforsch 1201 93. h e . dunayev. n. n. & pavlidis, j. a . 1988: a model of the late pleistocene glaciation of eurasiatic arctic shelf. pp. 7&72 in kotlyakov, v. m. & sokolov. v. e . (eds.): arctic research advances and prospects, vol. 2. proceedings of the c o i i ference of arctic and nordic countries on coordination of research in the arctic, academy of sciences of the ussr. leningrad, december 1988. emelyanov. e. m.. pilipchuk, m. f., volostnykh. b. v . , khandros. g . s. & shaidurov, yu. 0 . 1 9 8 2 : fe and mn forms in sediments in the geochemical profile of the baltic sea. baltica 7, 15s171. fiitterer, d. k. (ed.) 1992: arctic‘91: the expedition ark viii/3 of rv “polarstern” in 1991. ber. polarforsch. 107/92. 267 pp. fiitterer, d. k. (ed.) 1994: the expedition arctic93 leg ark 1x14 of rv “polarstern” 1993. ber. polarforsch. i # / 94. 244 pp. gard, g. 1988: late quaternary calcareous nannofossil bio chronology and paleo-oceanography of arctic and subarctic seas. medd. stockholm uniu. geol. inst. 275. w 5 . gierloff-emden, h . g . 1982: das eis des meeres. walter de gruyter, berlin, 767-940 pp. gordeev, v. v. & sidorov, i. s . 1993: concentrations of major elements and their outflow into the laptev sea by the lena river. mar. chem. 43. 3s45. grosswald. m. g . 1988: late pleistocene ice sheet in the soviet arctic. pp. 18-23 in kotlyakov, v . m. & sokolov, v. e . (eds.): arctic research advances and prospects vol. 2. proceedings of the conference of arctic and nordic countries on coordination of research in the arctic. academy of sciences of the ussr. leningrad, december 1988. holmes, m. l. & creager, j. s. 1974: holocene history of the laptev sea continental shelf. pp. 211-229 in herman, y. (ed.): marine geology and oceanography of the arctic seas. springer verlag, berlin. kassens, h . & karpiy. v. y . 1994: russian-german coop eration: the transdrift i expedition to the laptev sea. ber. polarforsch. 151194. 168 pp. middtun, l. 1985: formation of dense bottom water in the barents sea. deep-sea res. 32 ( l o ) , 123s1241. milliman, j . d. & meade, r. h . 1983: world-wide delivery of river sediment to the oceans. j . geol. 91. 1-21. nurnberg, d.. wollenburg, i . , dethleff, d . , eicken, h . . kassens, h.. letzig, t., reimnitz, e. & thiede. j . 1994: sediments in arctic sea ice implications for entrainment. transport and release. mar. geol. 119, 185-214. nowaczyk, n. 1991: high-resolution magnetostratigraphy of late-quaternary arctic marine sediments. ber. polarforsch. 78/91. 187 pp. stein, r. & nurnberg, d. 1995: organic carbon and biogenic opal in surface sediments from the laptev sea and the adjac ent continentalslope. in kassens, h . . thiede, j., hubherten. h . w., piepenburg, d . , priamikov, s . & timokhov. l. (eds.): second workshop on “russian-german cooperation in and around the laptev sea”, st. petersburg. november 1994. ber. polarforsch. (first version. february 1995). vorren, t. 0.. hald, m., edvardsen, m. & lind-hansen, 0. w. 1983: glacigenic sediments and sedimentary environ ments on continental shelves: general principles with a case study from the norwegian shelf. pp. 61-73 in ehlers, j . (ed.): glacial deposits in north-west europe. balkema, rotterdam. zenkovitch, v. p. 1985: arctic ussr. pp. 863-871 in bird, e. c. f. & schwarz, m. l. (eds.): the world’s coastline. van nostrand reinhold company, new york. khim.indd 341khim & yoon 2003: polar research 22(2), 341–353 during the last decade, marine geological and geophysical researchers have carried out extensive bathymetric surveys around the continental shelves of the antarctic peninsula which contain a portion of the marine-based west antarctic ice sheet (domack & ishman 1993; pudsey et al. 1994; pudsey & camerlenghi 1998; shipp et al. 1999; canals et al. 2000). the incised glacial troughs observed on the continental shelves of the antarctic pen insula preserve thick sediment fi lls derived from grounded ice shelves which built up during the last glacial period. sugden & clapperton (1977) have suggested that during the last glacial maximum many ice caps formed on the south shetland islands, which were separated from the antarctic peninsula ice sheet by the deep bransfi eld strait. the timing of the onset of deglaciation in the postglacial marine environmental changes in maxwell bay, king george island, west antarctica boo-keun khim & ho il yoon sediment textural properties and total organic carbon (toc) contents of three sediment cores from maxwell bay, king george island, west antarctica, record changes in holocene glaciomarine sedimentary environments. the lower sedimentary unit is mostly composed of toc-poor diamictons, indicating advanced coastal glacier margins and rapid iceberg discharge in proximal glaciomarine settings with limited productivity and meltwater supply. fine-grained, toc-rich sediments in the upper lithologic unit suggest more open water and warm conditions, leading to enhanced biological productivity due to increased nutrient-rich meltwater supply into the bay. the relationship between toc and total sulfur (ts) indicates that the additional sulfur within the sediment has not originated from in situ pyrite formation under the reducing condition, but rather may be attributed to the detrital supply of sand-sized pyrite from the hydrothermal-origin, quartz–pyrite rocks widely distributed in king george island. the evolution of bottom-water hydrography after deglaciation was recorded in the benthic foraminiferal stable-isotopic composition, corroborated by the toc and lithologic changes. the δ18o values indicate that bottom-water in maxwell bay was probably mixed gradually with intruding 18o-rich seawater from bransfi eld strait. in addition, the δ13c values refl ect a spatial variability in the carbon isotope distribution in maxwell bay, depending on marine productivity as well as terrestrial carbon fl uxes by meltwater discharge. the distinct lithologic transition, dated to approximately 8000 yr bp (uncorrected) and characterized by textural and geochemical contrasts, highlights the postglacial environmental change by a major coastal glacier retreat in maxwell bay. b.-k. khim, dept. of marine science and marine research institute, pusan national university, pusan 609-730, south korea, bkkhim@ pusan.ac.kr; h. i. yoon, korea polar research institute, korea ocean research and development insti tute, box 29, ansan 425-600, south korea. 342 postglacial marine environmental changes in maxwell bay, king george island region of the antarctic peninsula, particularly the south shetland islands, is still subject to debate. based on the sediment accumulation in the several freshwater lakes of the ice-free basin, different opinions on the holocene glacial and palaeoclimate history of the south shetland islands have been offered. some investigators argue that the present-day warm environment dates back to about 5000 6000 yr bp (mäusbacher et al. 1989; björck et al. 1991; björck et al. 1993). martinezmacchiavello et al. (1996) corroborated the complete deglac iation on king george island by ca. 6000 yr bp. in contrast, it has been reported that deglaciation generally commenced in the south shetland islands before at least 10 000 yr bp (john 1972; sugden & clapperton 1986). clapperton & sugden (1982) proposed that the extensive glaciers in the south shetland islands were developed at about 9500 yr bp. in addition, mäusbacher et al. (1989) reported that the last deglaciation occurred between 9000 and 5000 yr bp in king george island, based on the dates constrained with the lake sediments. during the glacial period, the ice sheet expanded to the continental shelves, leading to the formation of consecutive prograding shelf edge clinoforms indicatative of subglacial and proglacial sediment gravity fl ow deposition (larter & vanneste 1995). in contrast, during deglaciation, the ice sheet rapidly retreated from the continental shelves, as substantiated by subglacial geomorphic features. postglacial warming caused the collapse of grounded ice followed by increased meltwater discharge from the neighbouring coastal margins. this meltwater delivered large amounts of fi ne-grained particles to the continental shelves via shallow marine bays and fjords (pudsey 2000; yoon et al. 2000; taylor et al. 2001). thus, the shallow marine bays and fjords record such palaeoclimatic changes. however, information on the deglacial palaeoceanographic features of these fjords in king george island is still limited. fjord sediments typically contain the potential records of past biotic, climatic and glacial fl uctuations (syvitski 1989). the shallow areas of the antarctic peninsula region, especially in fjords, bays and coves, are the appropriate place to investigate deglacial marine environmental change. advances and retreats of grounded ice in such environments are key factors determining depositional processes and sediment distribution (yoon et al. 1997; kirby et al. 1998; pud sey 2000). recently, li et al. (2000) investigated surface textures of foraminiferal tests in maxwell bay, king george island, located in the south fig. 1. core sites and bathymetry of maxwell bay, king george island, south shetland islands. arrows represent the current direction of glacier movement. abbreviations: cb–collins bay, mc–marian cove, pc–potter cove. the bathymetry is in metres. 343khim & yoon 2003: polar research 22(2), 341–353 shetland islands (fig. 1). they have reported that the sea level rise and concomitant infl ux of open ocean waters during deglaciation led to a strong dissolution of foraminiferal tests. the retreat of coastal glaciers increased meltwater fl ux into the bay, resulting in higher biological productivity (domack & ishman 1993; domack & mcclennen 1996; shevenell et al. 1996; kirby et al. 1998). thus, higher rates of organic matter accumulation may have played an additional role in the carbonate dissolution due to porewater acidifi cation by organic matter oxidation. in this study, we widen the palaeoenvironmental study of postglacial sediments by using new data concerning grain size and the geochemistry of postglacial sediments, as well as stableisotope composition of benthic foraminifera, and by establishing the chronology with accelerated mass spectrometry radiocarbon dates obtained from three sediment cores in maxwell bay (fig. 1). these results contribute to the reconstruction of the deglacial and holocene environments of the coastal area of king george island. the study area king george island’s maxwell bay is 14 km long and 6 14 km wide (fig. 1). it is one of the deep, u-shaped fjords found along the southern margin of the south shetland islands. it is surrounded by ice cliffs creeping from the low profi le ice cap of fildes peninsula and nelson island. maxwell bay is separated from bransfi eld strait by a deep (> 430 m water depth) submarine sill. water depth increases gradually from the coastline to the 200 m isobath, and then steeply to the 550 m isobath. at 65° s, the study area experiences a slightly more moderate climate (cold temperate to subpolar) compared to the main antarctic peninsula region. the surface waters of maxwell bay freeze regularly in winter, from late july to midseptember. a surface layer of warmer (1.04 to 0 °c), less saline (33.85 to 34.0 psu) and lower δ18o (− 0.44 to − 0.30 ‰) water overlies a colder (0 to − 0.34 °c), more saline (34.0 to 34.53 psu) and higher δ18o (− 0.30 to − 0.17 ‰) subsurface water mass (khim et al. 1997). the temperature and salinity differences between the surface and subsurface waters are approximately 1 °c and 0.6 psu, respectively. the δ18o values are below – 0.30 ‰ in the surface water and above –0.20 ‰ in the subsurface water. because maxwell bay is connected directly to bransfi eld strait over a relatively deep submarine sill, bransfi eld strait water (open ocean water) is well circulated with the subsurface water in the bay (hong et al. 1991; khim et al. 1997). the surface water is governed by the freshwater input from glacial melting and surface runoff. several tributaries were developed in maxwell bay, including marian cove and potter cove in the north-east and collins bay in the north (fig. 1). from late october, sea ice begins rapidly to break up and numerous icebergs are scattered in maxwell bay. active iceberg calving from the tidewater glacier terminus was observed in collins bay during the austral summer (yoon et al. 1998). small valley glaciers draining into marian cove also deliver icebergs and large volumes of turbid meltwater during the summer months (yoon et al. 1998). potter cove, a tributary inlet near the entrance of maxwell bay, is characterized by large meltwater discharge, but no calving of icebergs has been observed (klöser et al. 1994). most ice-rafted debris therefore originates from the calving of icebergs off the edges of glaciers, whereas fi ne-grained particles are discharged by meltwater during the summer season. the bay becomes completely ice-free during the summer (november–february), leading to increased primary biological production. materials and methods in 1997, three gravity cores were collected from collins bay (a10-02), marian cove (a10-01) and potter cove (a10-08) in maxwell bay aboard the rv yuzhmorgeologiya during the tenth korea antarctic research expedition (fig. 1, table 1). each core was cut in the laboratory and then subsampled at 5-cm intervals for analyses of grain size, total organic carbon (toc) and total sulfur (ts). grains larger than 63 µm (gravel and sand) were separated by wet sieving and classitable 1. location, water depth, and core length of sediment gravity cores that were obtained in the maxwell bay. core latitude longitude water depth core length a10-01 62° 13.0' w 58° 47.5' s 85 m 235 cm a10-02 62° 11.3' w 58° 49.7' s 105 m 270 cm a10-08 62° 13.7' w 62° 39.7' s 45 m 105 cm 344 postglacial marine environmental changes in maxwell bay, king george island fi ed by dry sieving. grains smaller than 63 µm (silt and clay) were analysed using a micrometrics sedigraph 5100d. after removing caco3 by 10 % hcl from the bulk sediment powders, toc and ts were measured using a carlo-erba na1500 elemental analyzer at kordi. oxygen and carbon stable isotopic values were determined on the tests of benthic foraminifera (globocassidulina biora), ranging in size from 150 to 250 µm. because some foraminiferal tests show the dissolution texture (li et al. 2000), specimens for analyses were carefully selected. after treatment at 350 °c for 1 hour under vacuum to remove organic matter, samples were then reacted with h3po4 at 90 °c in an on-line automated carbonate co2 preparation device connected to a vg prism ii mass spectrometer at the university of california, santa barbara. the instrumental precisions of isotopic measurement are ± 0.11 ‰ for δ18o and ± 0.09 ‰ for δ13c based on the internal standards. all values are expressed in the δ notation in accordance with the v-pdb standard (craig 1957; coplen 1996). accelerator mass spectrometry (ams) radiocarbon (14c) ages were measured at the institute of geological and nuclear sciences, new zealand, using the acid-insoluble organic matter fraction of bulk sediments. results chronology of core sediments because we did not collect box cores for precise age determination of surfi cial sediments, the core-top ages of each gravity core are estimated by the extrapolation of the regressions based on the measured 14c ages (table 2). the extrapolated ages of core-tops are approximately 5061 yr bp for core a10-01, 3555 yr bp for core a10-02 and 5128 yr bp for core a10-08 (fig. 2). these extrapolated surface ages are signifi cantly larger than the typical reservoir correction for antarctic marine environments, although the ocean reservoir correction may have changed during the glacial–interglacial cycles. in general, the ocean reservoir effect for the antarctic marine carbonates accounts for about 1200 to 1300 years (gordon & harkness 1992; berkman & forman 1996). however, it has been reported that radiocarbon ages obtained from acid-insoluble organic fraction of surfi cial sediments are substantially older and often range between 2000 and 5000 years (domack 1992; andrews et al. 1999; pudsey & evans 2001). such large discrepancies between the apparent reservoir correction and the measured 14c ages from sediment organics may be attributed to the old carbon contamination caused either by the liberation of co2 stored in the ice sheets (domack et al. 1989), along with the uptake of “old” dissolved inorganic carbon by diatoms (gibson et al. 1999), or by the assimilation of dissolved inorganic carbon by diatoms during co2 limiting conditions (tortell et al. 1997). otherwise, the core-top sediments seem to be lost during the coring process. therefore, in this study, we give the uncorrected measured radiocarbon ages in describing the downcore varfig. 2. relationship between measured ams 14c ages (bulk sediments) and core depths (see table 2). estimated linear sedimentation rates are shown for each core. the dotted line represents the sedimentation rate of core a10-01 averaged from two segments. 9.0 cm/ky 22.7 cm/ky 27.8 cm /ky table 2. ams 14c radiocarbon ages measured on bulk sediment organic carbon. core depth (cm) measured 14c age (yr bp) δ13c (‰) lab code a10-01 5 5313 ± 71 –31.6 nza8021 103 8649 ± 70 –35.8 nza8030 232 13461 ± 98 –40.0 nza8045 a10-02 4 3688 ± 73 –27.7 nza8025 120 8851 ± 73 –34.1 nza8026 a10-08 10 6234 ± 69 –32.3 nza8022 38 9365 ± 93 –38.6 nza8023 345khim & yoon 2003: polar research 22(2), 341–353 iation in sedimentological and geochemical properties. sedimentation rates of core sediments linear sedimentation rates were calculated by inter polation between the 14c-dated levels, although sedimentation rates might vary during depos ition (fig. 2). the apparent linear sedimentation rates are 27.8 cm/ky (thousand years) for core a10-01, 22.7 cm/ky for core a10-02 and 9.0 cm/ky for core a10-08. the sedimentation rates in cores a10-01 and a10-02 are comparable to those of glacimarine sediments in marguerite bay and gerlache strait in the antarctic peninsula (20 50 cm/ky; harden et al. 1992), but still one order of magnitude lower than those in lallemand fjord, andvord bay and granite harbor (100 250 cm/ky; leventer et al. 1993; domack & mcclennen 1996; kirby et al. 1998; taylor et al. 2001). the sedimentation rate in porter cove (core a10-08) is one order of magnitude lower than in other areas of maxwell bay, in spite of the meltwater discharge from many small creeks (klöser et al. 1994). such a low sedimentation rate may be due to low amounts of suspended particles delivered by meltwater from the discharge basin. alternatively, the suspended particles delivered into potter cove may transit to maxwell bay because of a small depositional accommodation and the tidal action. grain size of core sediments downcore variation of sediment properties, including granulometric components and geochemical properties such as toc and ts, are shown in fig. 3. measured ams radiocarbon ages are also added on the core profi les; there is no reversal in the age throughout the cores. based on sediment properties, all three cores can be divided clearly into two lithologic units: (1) an upper unit composed of fi ne-grained mud with scattered, minor ice-rafted debris; and (2) a lower unit composed mostly of diamicton. xradiographs of core sediments clearly identify the distinct textural contrast of the two lithologic units (fig. 4). the upper unit is dominated by silt and clay in cores a10-01 and a10-02, but sand and gravel occur in core a10-08—as much as 25 % in content (fig. 3). the coarse fraction in core a10-08 is probably accounted for by the core’s location close to the coast, where terrigenous clastic particles are common. the lower unit of diamicton is characterized by mixed sediments with large amounts of gravel and sand (fig. 3). the near absence of gravel in core a10-02 may be attributed to the limited activity of the coastal glaciers. although the vertical profi le of mean grain size shows an overall decreasing trend, more frequent fl uctuations occur in the lower unit due to the diamictic sediment composition. the distinct textural contrast between the upper and lower lithologic units is also identifi ed by the mode of change in individual grain size classes (fig. 5). such a change in grain size mode refl ects variation with respect to the sediment transport mechanisms. the formation of the lower unit can be explained by advanced glacier margins with rapid iceberg discharge and limited meltwater supply. because it is generally diffi cult to distinguish subglacial tills from glacial marine diamictons based solely on visual appearance or a single attribute of the sediments (see licht et al. 1999), further analytical research on diamictons is necessary to constrain the interpretation of depositional environments. toc, ts and their relationship with grain size data downcore variation of toc content shows up wardly increasing values, matching the lithologic changes (fig. 3). in the diamicton, toc contents are less than 0.1 %, whereas the fi negrained sediments contain as much as 0.5 %. such a high toc value is similar to that of the reported modern surface sediments from andvord bay (domack & ishman 1993). toc contents usually depend on sediment grain size. most of the organic matter in shallow marine sediments is closely linked to the mineral matrix, occurring as organic coating adsorbed on the mineral surfaces (keil et al. 1994). thus, a negative correlation between toc and sediment coarseness is almost universally observed in the noncarbonate sediments in marine and lacustrine environments. figure 6 shows the relationship between toc contents and mean grain size. toc contents of the core sediments are largely determined by the amounts of clay particles in the sediments, although overall toc content is mostly low. the positive linearity between the two parameters is expected in spite of the different correlation coeffi cient in the size fractions. 346 postglacial marine environmental changes in maxwell bay, king george island fig. 3. vertical profi les of sediment properties (granulometric content, mean grain size, total organic carbon and total sulfur contents) from cores (a) a10-01, (b) a10-02 and (c) a10-08. measured radiocarbon ages are indicated at the right side of column. the hatched area represents the transition zone from diamicton to mud. (a) (b) (c) 347khim & yoon 2003: polar research 22(2), 341–353 it has been suggested that the ratio of organic carbon to pyrite sulfur (toc/ts) can be used to distinguish between marine and freshwater sediments (berner & raiswell 1984). in normal marine sediments, the sulfur mainly originates from organic matter and/or pyrite minerals. the limiting factor for pyrite formation under normal oxic seawater conditions is the amount of organic matter, which determines reducing conditions in the near-surface sediments (berner 1982). figure 6 also shows the interesting relationships between toc and ts in core sediments. two divided opposite trends between toc and ts are observed in core a10-08 (fig. 6f), which is diffi cult to explain. in contrast, the other two relationships of cores a10-01 and a10-02 are more hyperbolic (fig. 6d, e). in the case of the hyperbolic relationship, the pyrite seems to be the main contributor of surplus sulfur because of the low toc content and therefore the insuffi cient formation of sulfi de minerals in situ in the reducing environment. in core sediments of a10-01 and a10-02, high ts contents are closely related to the sand fraction (figs. 4, 6), implying that terrestrial material seems to be a main source for sulfur. the increase of ts content can be attributed to an input of terrestrial pyrite of hydrothermal origin—quartz–pyrite rocks, which have been recognized and described by many invesfig. 4. x-radiograph of core a10-01 showing the lithologic feature of upper (fi ne-grained mud with scattered ice-rafted debris) and lower sedimentary (mostly diamictons) units. fig. 5. variation of grain size class distribution in sediment core a10-01. histogram of grain size classes represents the change of mode from lower to upper lithologic units. 348 postglacial marine environmental changes in maxwell bay, king george island tigators on king george island (littlefair 1978; so et al. 1995). stable-isotope composition of benthic foraminifera the downcore variation in δ18o and δ13c values of benthic foraminifera shows the deglacial transition, similar to the lithologic variation (fig. 7). the hatched areas mark the transition zone between the lower and upper sedimentary units (fig. 3). both δ18o and δ13c values vary in a small range (fig. 8), indicating relatively stable environmental conditions for the stable-isotope compositions. the δ18o values lie in the small range, between 3.7 ‰ and 4.1 ‰. however, some upcore increase in δ18o values can be identifi ed in the upper unit (fig. 7), although the increasing trend in δ18o values is not distinct in core a1008. the differences of δ18o values between the upper and lower units are about 0.1 ‰ for cores a10-01 and a10-02. the δ13c foraminiferal values in cores a1001 and a10-02 vary slightly between 0 and 1 ‰ (fig. 8). clustering of core a10-08 is clearly distinguishable. the δ13c values show a larger varifig. 6. (a c) relationships between total organic carbon (toc) and mean grain size, (d f ) between toc and total sulfur (ts), and (g i) between ts and sand content. the surplus sulfur with low toc is observed in cores a10-01 and a10-02. high ts contents are closely related to the sand fraction in a10-01 and a10-02, implying that terrestrial material is the main source for sulfur. (a) (b) (c) (d) (e) (f) (g) (h) (i) 349khim & yoon 2003: polar research 22(2), 341–353 ation and lighter values of –1.5 to 0 ‰ in this core. this may be due to a depth difference between the core sites, with the shallowest depth of a1008 infl uenced by meltwater discharge. all three cores show a gradual increase in δ13c values in the upper unit, possibly refl ecting the infl ow of shelf water with sea level rise and glacier retreat (yoon et al. 2000; khim et al. 2001). in addition, the higher productivity during the warm postglacial period enhanced the content of heavy carbon in the seawater carbonate pool (arthur et al. 1983). fluctuations of δ13c values throughout the lower unit of cores a10-02 and a10-08 are likely due to redeposition of pre-glacial sediments, through reworking of the coarser particles. otherwise, the poor preservation of foraminiferal specimens and their secondary alteration may affect the isotope signals. discussion postglacial marine environmental change in maxwell bay sedimentary and geochemical properties show that all three cores in maxwell bay are characterized by two lithologic units (fig. 3). the upper unit consists of fi ne-grained mud with scattered, minor ice-rafted debris. the lower unit is mostly diamicton. the main boundaries of the lithologic changes from diamictons to the fi ne-grained mud are at downcore depths of approximately 105, 120 and 45 cm in cores a10-01, a10-02 and a10-08, respectively. among three cores, the transitional boundaries of a10-01 and a10-02 are comparable in age: 8649 and 8951 yr bp, respectively. based on previous studies in the antarctic peninsula, the fi ne-grained sediments comprising the upper unit document open water conditions of an ice-distal environment, whereas the fig. 7. downcore variation of stable isotopes in benthic foraminifera. the hatched area represents the transition zone from diamicton to mud. fig. 8. biplot of δ18o and δ13c values of benthic foraminifera. 350 postglacial marine environmental changes in maxwell bay, king george island coarse diamictons in the lower unit record an ice-proximal environment (see shevenell et al. 1996; yoon et al. 1997; kirby et al. 1998; pudsey 2000; taylor et al. 2001). thus, the accumulation of fi ne-grained mud in the upper unit was likely infl uenced by sediment-deriven meltwater infl ux during a warm climate regime after the completion of deglaciation (kirby et al. 1998). this indicates fast deglaciation, probably due to a sea level determined ice break-up and subsequent calving (yoon et al. 2000). the resulting upper unit in the sediment cores is characterized by relatively high toc, derived from enhanced productivity concomitant with nutrient enrichment (fig. 3). in polar fjord sediments, organic carbon enrichment may result from the increased vertical settling of organic carbon due to high productivity in surface water (domack & mcclennen 1996; kirby et al. 1998). otherwise, less dilution by more terrigenous input associated with ice-proximal meltwater plumes and/or reworking of bottom sediments may enhance the preservation of toc within the sediments (shevenell et al. 1996). the low toc contents in the lower unit may be attributed to the limit and reduction of organic carbon production mainly due to the advanced coastal glacier margin, with extensive sea ice coverage inhibiting primary production in surface water. this period corresponds roughly with a cold condition recorded on nearby livingstone island and in lake sediments on james ross island (björck et al. 1996). it also matches a cold event documented in the sediment cores from lallimand fjord, antarctic peninsula (shevenell et al. 1996). in contrast, the high toc contents in the upper unit may be caused by the enhanced primary production in the surface water, due to a higher delivery of nutrients by meltwater discharge during the warm period (yoon et al. 2000; khim et al. 2001; taylor et al. 2001). the increased productivity in the upper unit is also supported by the biogenic silica (bsi) content and positive relationship between the bsi and the toc (fig. 9). such high toc is largely accounted for by increased diatom abundance. thus, the clear disparity in toc contents corresponding to lithologic changes refl ects a range of depositional environments, from ice-proximal to ice-distal condition (fig. 3). the environmental transition from diamicton to fi ne-grained sediments is also supported by δ18o variation in benthic foraminifera from shallow marine environments, although it is tenuous because of complex hydrographic parameters determining the stable-isotope compositions (arthur et al. 1983). in particular, dominant incorporation of oxygen from freshwater to the carbonate precipitation complicates the determination of the temperature effect and the δ18o content of seawater. furthermore, stable temperatures in antarctic ocean waters could hardly add any noticeable temperature-controlled variation in the carbonate stable-isotope composition (charles & fairbanks 1990). today, the bottomwater temperature in maxwell bay is stable and consistently lower than 0 °c (khim et al. 1997). during the deglacial period, the bottom-water temperature may have been higher. here, we fig. 9. comparison of vertical variation between total organic carbon (toc) and biogenic silica (bsi) (modifi ed from kim et al. 1999; printed with permission of geosciences journal). the strong positive relationship indicates a high biological productivity in the upper unit, largely composed of diatoms. 351khim & yoon 2003: polar research 22(2), 341–353 assume that benthic foraminifera in this environment mostly represent bottom-water stableisotope properties by inheriting the δ18o and δ13c compositions of ambient seawater at the time of precipitation. during the postglacial time, the increasing δ18o values may be due to the marine seawater intruding into maxwell bay from bransfi eld strait, not the decrease of bottom-water temperature. although the surfi cial meltwater discharge increases with warming, the bottom-water in maxwell bay is still connected with the saline water of bransfi eld strait. higher δ18o values (− 0.2 ‰) of shelf water in the strait are contrasted with those (− 0.3 ‰) of seawater in maxwell bay (khim et al. 1997). we infer that with the retreat of grounded coastal glaciers and the reduction of sea ice coverage, more seawater from bransfi eld strait entered maxwell bay, resulting in heavier δ18o values in benthic foraminifers. however, later in the holocene, δ18o values decreased, probably due either to higher temperatures or to stronger dilution by meltwater. holocene marine environmental change in south shetlands islands marine geological and geophysical studies have shown that the shallow marine environments around the antarctic peninsula were covered by grounded ice sheets during the last glaciation (domack & ishman 1993; pudsey et al. 1994; pud sey & camerlenghi 1998; shipp et al. 1999). in particular, sedimentary and lithologic investigations have demonstrated that lapeyrere bay (anvers island), cierva cove (danco coast), lallemand fjord, andvord bay and brialmont cove preserve a characteristic change in sediment lithology type from glacier-proximal coarsegrained sediments to distal sandy, biosiliceous muds (domack & mcclennen 1996; kirby et al. 1998; khim et al. 2001; taylor et al. 2001). downcore variation in toc complements the interpretation of depositional environments and allows the reconstruction of palaeo environmental conditions. the elevation of toc contents represents a time when the vertical fl ux of organic carbon throughout the fjord was higher, under favourable preservation conditions. the lithologic transition from coarse-grained diamicton to homogeneous mud in maxwell bay refl ects a major coastal-ice retreat, dated to approximately 8000 yr bp. a similar date was obtained from the lake sediment cores in king george island (mäusbacher et al. 1989). assuming that the ice sheet break-up was bathymetrically controlled by ice retreat toward the island, we infer a similar time for the glacimarine– marine transition in king george island; this is also supported by dates from the marine cores in admiralty bay, king george island (khim et al. 2001). during postglacial period, the ground-line retreating of the coastal glacier and the diminished sea ice coverage resulted in rapid and enhanced primary production in maxwell bay. with the increased productivity, abundant benthic foraminifera were deposited in the postglacial sediment, with an upcore trend of increasing toc (fig. 3; li et al. 2000). judging from the steady increase in toc, the climate became gradually warmer. regionally, this interpretation is corroborated by lake sediments from king george island (schmidt et al. 1990) and james ross island (björck et al. 1996). it also corresponds to the period of open marine conditions recorded in the sediment core from lallimand fjord, antarctic peninsula (shevenell et al. 1996). the postglacial records of south shetland islands, including maxwell bay of king george island, are comparable to those of the fjords of the antarctic peninsula, and east and west antarctica, revealing both similarities and anomalies between the regions (domack & mcclennen 1996). the sedimentological and geochemical data generally represent a transition from iceproximal to open marine deposition. this is strongly supported by the presence of the iceassoc iated diatom assemblage in open marine envi ron ments (leventer et al. 1993; taylor et al. 2001). in addition, the increasing toc suggest increasing primary production and may refl ect dilu tion of this signal due to increased siliclastic sed imentation. during the mid-holocene, the climate generally became warmer and more humid, showing high productivity peaks in the marine records. in particular, lake sediment data from south georgia (rosqvist et al. 1999) and james ross island (björck et al. 1996), and even marine sed iments in the ross sea, suggest that atmospheric temperatures were warmer than present during that time. conclusions sediment textures and geochemical properties of three sediment cores from maxwell bay, king 352 postglacial marine environmental changes in maxwell bay, king george island george island, record changes in glacimarine environments, which occurred during coastal glacier retreat, accompanied by increased meltwater discharge and postglacial warming. coupled lithologic and geochemical changes demonstrate that the lower diamictons represent advanced glacier margins and/or extensive sea ice cover, which limited primary biological production and meltwater supply. in contrast, the younger unit, composed mainly of fi ne-grained particles, indicates more open water and warmer conditions, favourable for enhanced production. comparison between toc and ts suggests that the additional sulfur, characteristic of the lower unit, originated from the nearby hydrothermal-origin, quartz– pyrite rocks of king george island, but not from the in situ pyrite formation under reducing conditions. benthic foraminiferal stable-isotope composition indicates that bottom-water conditions in maxwell bay were affected by shelf water inputs from bransfi eld strait after deglaciation. the lithologic transition occurring at about 8000 yr bp (14c age), in the mid-holocene, supports previous results reported for king george island. acknowledgements.⎯this research was supported by the korea polar research program (pp03106). we thank the captain and crew of the rv yuzhmorgeologiya. outdoor sampling of gravity cores and laboratory work were specially assisted by c. y. kang and y. s. yang, both of the korea ocean research and developement institute. thanks go to dr j. m. kim (university of california, santa barbara) for analysing the stable-isotope composition of the benthic foraminifera. dr h. j. lee’s (korea ocean research and developement institute) painstaking efforts reading and editing the manuscript are appreciated. we thank dr b. diekmann and an anonymous reviewer for their critical reviews, which improved our interpretation. references andrews, j. t., domack, e. w., cunningham, w. l., leventer, a., licht, k. j., jull, a. j. t., demaster, d. j. & jenning, a. 1999: problems and possible solutions concerning radiocarbon dating of surface marine sediments, ross sea, antarctica. quat. res. 52, 206–216. arthur, m. a., anderson, t. f., kaplan, i. r., veizer, j. & land. l. s. 1983: stable isotopes in sedimentary geology. sepm short course notes 10. tulsa, ok: society for sedimentary geology. berkman, p. a. & forman, s. l. 1996: pre-bomb radiocarbon and the reservoir correction for calcareous marine species in the southern ocean. geophys. res. lett. 23, 363–366. berner, r. a. 1982: burial of organic carbon and pyrite sulfur in the modern ocean: its geochemical and environmental signifi cance. am. j. sci. 278, 451–473. berner, r.a. & raiswell, r. 1984: c/s method for distinguishing freshwater from marine sedimentary rocks. geology 12, 365–368. björck, s., håkansson, h., olsson, s., barnekow, l. & janssens, j. 1993: paleoclimatic studies in south shetland islands, antarctica, based on numerous stratigraphic variables in lake sediments. j. paleolimnol. 8, 233–272. björck, s., hjort, c., ingólfsson, o. & skog, g. 1991: radiocarbon dates from the antarctic peninsula—problems and potential. in j. j. lowe (ed): radiocarbon dating: recent applications and future potential. pp. 55–65. cambridge: cambridge university press. björck, s., olsson, s., ellis-evans, c., håkansson, h., humlum, o. & manuel de lirio, j. 1996: late holocene palaeoclimatic records from lake sediments on james ross island, antarctica. palaeogeogr. palaeoclimatol. palaeoecol. 121, 195–220. canals, m., urgeles, r. & calafat, a.m. 2000: deep sea-fl oor evidence of past ice streams off the antarctic peninsula. geology 28, 31–34. charles, c. d. & fairbanks, r. g. 1990: glacial to interglacial changes in the isotopic gradients of southern ocean surface water. in u. bleil & j. thiede (eds.): geologic history of the polar oceans: arctic versus antarctic. pp. 519–538. dordrecht, the netherlands: kluwer. clapperton, c. m. & sugden, d. e. 1982: late quaternary glacial history of george vi sound area, west antarctica. quaternary research 18, 243-267. coplen, t. 1996: new guidelines for reporting stable hydrogen, carbon, and oxygen isotope-ratio data. geochim. cosmochim. acta 60, 3359–3360. craig, h. 1957: isotopic standards for carbon and oxygen and correction factors for mass spectrometric analysis of co2. geochim. cosmochim. acta 12, 133–149. domack, e. w. 1992: modern carbon-14 ages and reservoir corrections for the antarctic peninsula and gerlache strait area. antarct. j. u. s. 27, 63–64. domack, e. w. & ishman, s. 1993: oceanographic and physiographic controls on modern sedimentation within antarctic fjords. geol. soc. am. bull. 105, 1175–1189. domack, e. w., jull, a. j. t., anderson, j. b., linick, t. w. & williams, c. r. 1989: application of tandem accelerator mass spectrometer dating to late pleistocene–holocene sediments of the east antarctic continental shelf. quat. res. 31, 277–297. domack, e. w. & mcclennen, c. e. 1996: accumulation of glacial marine sediments in fjords of the antarctic peninsula and their use as late holocene palaeoenvironmental indicators. antarct. res. ser. 70, 135–154. gibson, j. a. e., trull, t., nichols, p. d., summons, r. w. & mcminn, a. 1999: sedimentation of 13c-rich organic matter from antarctic sea-ice algae: a potential indicator of past sea ice extent. geology 27, 331–334. gordon, j. e. & harkness, d. e. 1992: magnitude and geographic variation of the radiocarbon content in antarctic marine life: implications for reservoir corrections in radiocarbon dating. quat. sci. rev. 11, 697–708. harden, s. l., demaster, d. j. & nittrouer, c. a. 1992: developing sediment geochronologies for high-latitude continental shelf deposits: a radiochemical approach. mar. geol. 103, 69–97. hong, g. h., kim, d. y., chung, h. & pae, s. 1991: coast353khim & yoon 2003: polar research 22(2), 341–353 al and inshore water interaction, mixing and primary productivity in the bransfi eld strait, antarctica during austral summer, 1989/1990. korean j. polar res. 2, 43–59. john, b. s. 1972: evidence from the south shetland islands towards a glacial history of west antarctica. in d. e. sugden & r. j. price (eds.): polar geomorphology. pp. 75– 92. london: institute of british geographers. keil, r. d., tsamakis, e., fuh, c. b., giddings, j. c. & hedges, j. i. 1994: mineralogical and textural controls on the organic composition of coastal marine sediments: hydro dynamic separation using splitt-fractionation. geochim. cosmochim. acta 58, 879–893. khim, b. k., park, b. k. & yoon, h. i. 1997: oxygen isotopic compositions of seawater in the maxwell bay of king george island, west antarctica. geosci. j. 1, 115–121. khim, b. k., yoon, h. i., kim, y. & shin, i. c. 2001: the holocene stable isotope chronology and meltwater discharge event in king george island of south shetland islands, antarctica. antarct. sci. 13, 167–173. kim, d., park, b. k., yoon, h. i. & kang, c. y. 1999: geochemical evidence for holocene paleoclimatic changes in maxwell bay of south shetland islands, west antarctica. geosci. j. 3, 55–62. kirby, m. e., domack, e. w. & mcclennen, c. e. 1998: magnetic stratigraphy and sedimentology of holocene glacial marine deposits in the palmer deep, bellingshausen sea, antarctica: implications for climate change? mar. geol. 152, 247–259. klöser, h., ferrerya, g., schloss, i., mercuri, g., laturnus, f. & curtosi, a. 1994: hydrography of potter cove, a small fjord-like inlet on king george island (south shetlands). estuar. coast. shelf sci. 38, 523–537. larter, r. d. & vanneste, l. e. 1995: relict subglacial deltas on the antarctic peninsula outer shelf. geology 23, 33–36. leventer, a., dunbar, r. b. & demaster, d. j. 1993: diatom evidence for late holocene climatic events in granite harbor, antarctica. paleoceanography 8, 373–386. li, b., yoon, h. i. & park, b. k. 2000: foraminiferal assemblages and caco3 dissolution since the last deglaciation in the maxwell bay, king george island, antarctica. mar. geol. 169, 239–257. licht, k. j., dunbar, n. w., andrews, j. t. & jennings, a. e. 1999: distinguishing subglacial till and glacial marine diamictons in the western ross sea, antarctica: implications for a last glacial maximum grounding line. geol. soc. am. bull. 111, 91–103. littlefair, m. j. 1978: the quartz-pyrite rock of the south shetland islands, western antarctic peninsula. econ. geol, 73, 1184–1189. martinez-macchiavello, j. c., tatur, a., servant-vildary, s. & del valle, r. 1996: holocene environmental change in a marine–estuarine sediment sequence, king george island, south shetland islands. antarct. sc. 8, 313–322. mäusbacher, r., muller, j., munnich, m. & schmidt, r. 1989: evolution of postglacial sedimentation in antarctic lakes (king george island). z. geomorphol. 33, 219–234. pudsey, c. j. 2000: sedimentation on the continental rise west of antarctic peninsula over the last three glacial cycles. mar. geol. 167, 313–338. pudsey, c. j., barker, p. f. & larter, r. d. 1994: ice sheet retreat from the antarctic peninsula shelf. cont. shelf res. 14, 1647–1675. pudsey, c. j. & camerlenghi, a. 1998: glacial–interglacial deposition on a sediment drift on the pacifi c margin of the antarctic peninsula. antarct. sci. 10, 286–308. pudsey, c. j. & evans, j. 2001: first survey of antarctic subice shelf sediments reveals mid-holocene ice shelf retreat. geology 29, 787–790. rosqvist, g. c., rieti-shati, m. & shemesh, a. 1999: late glacial to middle holocene climatic record of lacustrine biogenic silica oxygen isotopes from a southern ocean island. geology 27, 967–970. schmidt, r., mäusbacher, r. & muller, j. 1990: holocene diatom fl ora and stratigraphy from sediment cores of two antarctic lakes (king george island). j. paleolimnol. 3, 55–74. shevenell, a. e., domack, e. w. & kernan, g. m. 1996: record of holocene paleoclimate change along the antarctic peninsula: evidence from glacial marine sediments, lallenmand fjord. pap. proc. r. soc. tasm. 130, 55–64. shipp, s. anderson, j. b. & domack, e. w. 1999: seismic signature of the late pleistocene fl uctuation of the west antarctic ice sheet system in the ross sea: a new perspective. part i—geophysical results. geol. soc. am. bull. 111, 1486–1516. so, c. s., yun, s. t. & park, m. e. 1995: geochemistry of a fossil hydrothermal system at barton peninsula, king george island. antarct. sci. 7, 63–72. sudgen, d. e. & clapperton, c. m. 1977: the maximum ice extent on island groups in the scotia sea, antarctica. quat. res. 7, 268–282. sudgen, d. e. & clapperton, c. m. 1986: glacial history of the antarctic peninsula and south georgia. s. afr. j. sci. 82, 508–509. syvitski, j. p. m. 1989: on the deposition of sediment within glacier-infl uenced fjords: oceanographic controls. mar. geol. 85, 301–329. taylor, f., whitehead, j. & domack, e. 2001: holocene paleoclimate change in the antarctic peninsula: evidence from the diatom, sedimentary and geochemical record. mar. micropaleontol. 41, 25–43. tortell, p. d., reinfelder, j. r. & morel, f. m. m. 1997: active uptake of bicarbonate by diatoms. nature 390, 243–244. yoon, h., han, m. w., park, b. k., oh, j. k. & chang, s. k. 1997: glaciomarine sedimentation and paleo-glacial setting of maxwell bay and its tributary embayment, marian cove, in the south shetland islands, west antarctica. mar. geol. 140, 265–282. yoon, h., park, b. k., domack, e. w. & kim, y. 1998: distribution and dispersal pattern of suspended particulate matter in maxwell bay and its tributary, marian cove, in the south shetland islands, west antarctica. mar. geol. 152, 261–275. yoon, h. i., park, b. k., kim, y. & kim, d. 2000: glaciomarine sedimentation and its paleoceanographic implications along the fjord margins in the south shetland islands, antarctica during the last 6000 years. palaeogeogr. palaeoclimatol. palaeoecol. 157, 189–211. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /all /binding /left /calgrayprofile (dot gain 20%) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages true /colorimagedownsampletype /bicubic /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages true /grayimagedownsampletype /bicubic /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /fra <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> /enu (use these settings to create pdf documents with higher image resolution for improved printing quality. the pdf documents can be opened with acrobat and reader 5.0 and later.) /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308000200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e30593002537052376642306e753b8cea3092670059279650306b4fdd306430533068304c3067304d307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e30593002> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <feff0055007300650020006500730074006100730020006f007000630069006f006e006500730020007000610072006100200063007200650061007200200064006f00630075006d0065006e0074006f0073002000500044004600200063006f006e0020006d00610079006f00720020007200650073006f006c00750063006900f3006e00200064006500200069006d006100670065006e00200070006100720061002000610075006d0065006e0074006100720020006c0061002000630061006c006900640061006400200061006c00200069006d007000720069006d00690072002e0020004c006f007300200064006f00630075006d0065006e0074006f00730020005000440046002000730065002000700075006500640065006e00200061006200720069007200200063006f006e0020004100630072006f00620061007400200079002000520065006100640065007200200035002e003000200079002000760065007200730069006f006e0065007300200070006f00730074006500720069006f007200650073002e> /suo <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> /ita <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> /nor <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> /sve <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> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice use of satellite-linked telemetry to study steller sea lion and northern fur seal foraging r. l. merrick. t. r. loughlin, g . a . antonelis and r. hill merrick, r. l.. loughlin. t. r . , antonelis g. a . & hill. r. 1994: use of satellite-linked telemetry to study steller sea lion and northern fur seal foraging. polar research 13, 105-114. n one explanation for recent declines in some alaskan pinniped populations is that ecosystem changes may have reduced the availability of preferred prey. part of our evaluation of this hypothesis involves the use of satellite-linked telemetry to study steller sea lion (eumetopias jubatur) and northern fur seal (callorhinus ursinus) foraging. data on dives (depth and duration) and water temperatures are collected by satellite linked time-depth recorders (sltdr) glued to the backs of sea lions and fur seals. these data are then summarized and stored for later transmission. data are relayed back to land through noaa tiros-series satellites and are processed by service-argos (a u s f r e n c h consortium). these transmissions are also used to calculate at-sea and on-land locations of the animals through use of doppler shifts of the frequency of received transmissions. ultimately, diving and temperature can be reconciled with at-sea locations to compare foraging areas with locations of known prey stocks. richard l . merrick, thomas r. loughlin. and george a . antonelis. national marine mammal laboratory, alaska fisheries science center, national marine fisheries service. 7600 sand point way, n . e.. bin c15700, seattle8 washington 98115-0070. u s a ; roger hill, wildlife computers, 20630 n . e. 150th street, woodinville. washington 98072-7641, u s a . introduction recent population censuses of the steller sea lion (eumetopias jubatus) and northern fur seal (callorhinus ursinus) have documented signifi cant declines through most of their ranges (fowler 1985; merrick et al. 1987; loughlin et al. 1992). these declines have resulted in a listing of both species as depleted under the u.s. marine mam mal protection act, with steller sea lions also listed as threatened under the u.s. endangered species act. the cause of these declines remains unknown; however, one hypothesis is that changes in the abundance or quality of preferred prey have contributed to the declines (merrick et al. 1987; loughlin & merrick 1989). much is known about prey preferences of the two species, but feeding locations and depths, particularly for steller sea lions, remain largely unknown. a major reason for this lack of information has been the difficulty of obtaining data on foraging locations and diving of free-ranging marine animals. instruments which record diving depths over time (time-depth recorder or tdr) have existed since the 1970s and have allowed researchers to track some pin nipeds’ movements vertically in the water column during foraging trips (gentry & kooyman 1986). coupled with a separate vhf radio transmitter and a ship or aircraft with which to track the animal, it is possible to obtain at least a partial picture of foraging movements (goebel et al. 1991). application of this technique has received limited use due at least in part to the high costs of aircraft and ship time and the need t o recapture the animal t o recover the t d r . recent developments in satellite telemetry allow tracking of marine animals using satellite linked radio tags or platform transmitter terminals (hill et al. 1987; hills 1987; mate et al. 1987; stewart et al. 1989; heidi-jorgensen et al. 1991). through the service-argos system on board noaa tiros-series satellites, it is possible to track and retrieve data from free-ranging animals using uplink communications between platform transmitter terminals (fit) attached to animals and receivers onboard satellites. locations at sea are determined from the doppler shift of the frequencies of a series of signals received by the satellite (fancy et al. 1988; stewart et al. 1989). 106 r. l. merrick et al. by combining a ptt and a tdr it is possible to simultaneously determine locations and collect diving information while the animal is at sea. the tdr collects dive data which can be reported by the ptt while the animal is at sea or saved for later reporting while the animal is on land. this is particularly important for animals like steller sea lions which inhabit relatively inaccessible areas, return to their tagging site on an infrequent basis, and are difficult to capture t o retrieve the tdr. in this report we describe a satellite-linked time-depth recorder (sltdr) developed for pin nipeds and illustrate its use with data obtained from free-ranging steller sea lions. the report gives a sample of the results of an ongoing study of steller sea lion and northern fur sea foraging ecology. materials and methods design of the sltdr involved an evolution of hardware and software which began in the sum mer of 1988 with ground-truth tests at alaska's marmot island sea lion rookery (58"12'n, 151'50'w). at that time, a ptt was placed at three locations on the island to determine if sig nals would be received by the satellite from the types of locations at which sea lions haul out. signals were received by 81.2% of the 149 satellite passes occurring during the test, an average of 6.4 receptions per pass. locations were calculated from 55.7% of the passes. the service-argos system classifies the accuracy of locations as follows: class 3 is accurate to 150m, class 2 to 350 m, class 1 to 1 km, and class 0 has no accuracy assigned (service-argos 1984). of 84 location fixes calculated in this test, 27 (32.1%) were class 1, 32 (38.1%) were class 2, and 25 (29.8%) were class 3. class 0 locations were not available from the service-argos system at the time of this test. differences between class 1 and 3 fixes were around 0.5 km, while class 2 and 3 fixes were essentially identical. based on the reasonableness of these results, we decided to proceed with deployment of a unit on a free-ranging steller sea lion. a 1.0 watt, st 4 ptt produced by telonics of mesa, arizona, was deployed in january 1990 at marmot island (reference to trade names does not imply endorse ment by the national marine fisheries service, noaa). an adult female steller sea lion was anaesthetized using telazol (loughlin & spraker 1989), and the unit was attached with epoxy glue applied to mesh spread over the animal's back. this unit transmitted for 46 days. of 60 at-sea locations produced, 4 (6.7%) were class 2, 12 (20.0%) were class 1, and 44 (73.3%) were class 0. of 94 fixes received while the animal was ashore, 15 were class 0 locations. we compared these locations with class 3 locations from the same visit ashore and estimated the mean dif ference between class 0 and 3 fixes t o be 1.8 km. this test proved that signals would be suc cessfully received by the satellite while the animal was at sea. now the challenge was to develop a unit which would produce locations as well as collect, process, and transmit data o n dive depths and durations, surface times, and water tem peratures. this new unit (labelled as type-2) was a packaging by wildlife computers of their t d r with a telonics 1.0 watt st-5 ptt. differences between the type-2 unit and earlier type-1 designs included incorporation of a thermistor, an improved conductivity sensor for sensing sur facings, and major changes in software. depth measurements were accurate within 2 m to a maxi mum depth of 500 m. temperature was accurate to 0.1"c with a thermocouple response time of less than 120 milliseconds. size of the sltdr package was 10 cm by 17 cm by 3 cm with a mass of 800g. unit software controlled data collection, sum marization, and transmission. the unit collected data only while the animal was at sea; this was sensed using a conductivity switch. once the ani mal had gone to sea the unit collected depth and water temperature readings at 10-second intervals throughout the trip. depths and temperatures from the first dive of each hour were collected and stored in their entirety for later transmission. the maximum depth, the temperature at the maximum depth, and both dive and surface dur ations were saved for all dives. thus, at the end of the trip a complete sequential record of surface times, dive times, maximum dive depths, and temperatures at depth was available for trans mission. two transmission protocols were used: at-sea and on-land. while the animal was at sea, a data message was transmitted that included histograms of earlier dives. each day was subdivided into four 6-hour periods (i.e., 21o(m300,0300-4900, 0900-1500, and 1500-2100 local sun time). his tograms were separately summarized for dive use of satellite-linked telemetry to study depths and durations for each of the preceding four complete 6-hour periods (a total of eight histograms). the on-land protocol was used for transmission of the hourly dive and temperature profiles, and a chronological record of duration, maximum depth, temperature at maximum depth, and duration of subsequent surface inter vals. during 1990-92 we deployed 45 type-2 sltdrs in the gulf of alaska (n = 21), aleutian islands (n = 15), bering sea (n = l ) , and kuril islands (n = 8). the data presented here were collected from units attached t o two adult female steller sea lions during spring 1992. one unit (14080) was deployed at latax rocks, alaska (58"42'n, 152"30'w), in the gulf of alaska on 27 february 1992. the other unit (14072) was deployed at akun island, alaska (54"18'n, 165"31'w), in the bering sea on 8 march 1992. these results are presented as an illustration of the data available and analyses possible with sltdrs. results locations ninety-six locations were obtained during march 1992 for animal 14072 (54 on land and 42 at sea) and 212 locations for animal 14080 (112 on land and 100 at sea). on-land locations were spread relatively evenly among the four location accuracy classes (table 1); however, over one-half of the at-sea locations were class 0. the accuracy of at sea locations was similar for the two animals; tubk i . percentage of at-sea and on-land location fixcs by class for fcmalc stellcr sea lions 14072 and 14080. class 3 locations are accurate to 150 rn, class 2 to 350 m. class 1 to 1 km, and class 0 have no accuracy assigned. animal location location class 14072 14080 total on land at sea 38.9% 31.5% 22.2% 7.4% 59.5% 19.1% 21.4% 0.0% 22.3% 13.3% 40.2% 24.2% 59.0% 19.0% 16.0% 6.0% 21.7% 19.3% 34.3% 18.7% 59.1 % 19.0% 17.6% 4.2% steller sea lion and northern fur seal foraging 107 however, on-land locations showed distinctly dif ferent distributions (table 1). most (64.3%) of animal 14080s on-land locations were class 2 or better, compared to 29.6% for animal 14072. one trip made by animal 14080 is shown in fig. 1 . this trip lasted around 20 hours with 10 locations calculated. dive depth, duration, and temperature summaries the histogram records provided data for 755 dives from 43 6-hour time periods for animal 14072, and 3,040 dives from 83 time periods for animal 14080. the summary records provided data on fewer dives: 207 dives from 14072s eight trips and 1,216 dives from 14080s six trips. average dive depth for the two animals was 36.5 m and 42.9 m, respectively (table 2). these differences were significantly different (df = 1,419, t = 2.904, p = 0.004). mean dive durations were 2.4 minutes for each animal, and mean surface intervals were 4.2 and 4.0 minutes, respectively. mean water temperature at maxi mum dive depth was 2.2"c for 14072 and 3.9"c for 14080, a significant difference (df = 1419, t = 51.116, p = 0.000). water temperatures at depth were distinctly different for the two animals (fig. variations in dive parameters by time-of-day for animal 14080 are only remarkable in the strong mode in dive depth, duration, and temperature during 06004859 (fig. 3). these time-of-day pat terns implied that a relationship existed between dive depth, duration, and temperature. duration (r = 0.733, p = 0.000) and temperature (r = 0.490, p = 0.000) were significantly correlated with depth for animal 14080 (fig. 4a and 4c). however, only duration (r = 0.208, p = 0.004) was correlated with depth for 14072 (fig. 4b and 4d). the chronological trip record can be used to reconstruct the diving pattern from throughout a trip. for example, fig. 5a was created for the trip by animal 14080 shown in fig. 1 . the animal began diving to around 50 m as soon as it departed latax rocks. around minute 200, dive depths increased t o 190 m. the animal continued to dive to these depths for the next two hours. this was followed by a period of shallow dives, and then another deep diving period. finally, around min ute 700, deep diving ceased and the sea lion began traveling back towards latax rocks. tem 2). 108 r . l . merrick et al. '<:a .>... . , ((.. ,<p .... . ..,............ ... ,:,@$$y i.:.:.. i i \latax rocks shelikof strait 1 g 1 5 l 5 h 15245 i& 1 5 h 5 l 5 h peratures at the maximum dive depth increased with increasing dive depth (fig. 5b). also shown on fig. 5b are times when a dive profile (open circle) or both a dive profile and a location fix (closed circle) are available. dive depth and temperature profiles we received 107 profiles from animal 14072 and 239 profiles from animal 14080. figs. 6a and 6b describe one of the dives from animals 14080's first trip (noted as 'a' on figs. 1 and 5). here it can be seen that the animal made a relatively slow descent (1.4 m/seconds) to the presumed foraging 5840 fig. i . sample trip made from latax rocks, alaska by female steller sea lion 14080 during march 1992. point a indicates location of dive profile shown in fig. 6 . depth (190 m). the sea lions foraged at this depth for 200 seconds, and then returned to the surface at roughly the same speed as the descent. a location fix was available for this dive and from comparison with bathymetric charts, it appeared that the animal was foraging at the bottom. water temperatures fluctuated only slightly through the dive, ranging from 5.2"c at the surface to 5.4"c at the bottom. discussion our goal in development of the sltdr was to table2. summary dive statistics as reported from steller sea lions 14072 and 14080 during march 1992 from chronological records. dive dive surface depth duration interval temperature m x max. x max. x max. x range no. n (m) (4 (min) (min) (min) (min) ('c) ("c) 14072 207 36.5 164 2.4 6.0 4.2 42.2 2.2 1.3-2.6 14080 1216 42.9 198 2.4 11.0 4.0 i60.0 3.9 2.6-6.3 use of satellite-linked telemetry io study steller sea lion and northern fur seal foraging 109 0.5 0.4 l m .n k 0.3 a c 0 e . g 0.2 n 0.1 fig. 2. comparison of tcmperature distributions at dive depth for female steller sea lions 14072 (a, n = 207) and 14080 ( b , n = 1216) during march 1992. a animal 14080 0.4 0.3 0.2 n 7-a 1.3 2.3 z b temperature (c) animal 14072 l 3 3.3 4.3 5.3 6.3 temperature (c) combine data available from a tdr with the at sea locations produced by p l t s . results of the past 2 year's deployments of fifty sltdrs on sea lions and fur seals indicate this goal has been achieved. using the sltdr, we have learned that adult female steller sea lions forage close t o land in summer (within 20 km), make brief trips (<2 days), and dive to shallow depths (<30m). in winter, trips are much longer in distance (>300 km) and duration (up to several months), and dives are deeper (often >250m). sea lion pups by their sixth month are able to range more than 250 km, although their dives remain shallow (<20m) and brief (<1 minute). water tem perature data indicate sea lions can forage through a wide thermal regime. first results from cdult male fur seals in winter show that they disperse widely from their pribilof island summer breeding grounds and frequently dive deep (>250 m) . using the type-2 sltdr we are now obtaining at-sea locations superior in number and quality to those of our earlier experiences with a p l t only. our january 1990 deployment of a €"it at marmot island produced 60 at-sea locations over a 46-day period, and 6.7% were class 2 or better. the deployment on animal 14080 at latax rocks (60 km west of marmot island) yielded 100 at-sea locations during march 1992 (31 days), and 22.0% were class 2 or better. part of this difference was due to the improved surfacing (conductivity) sensor on the sltdr. simultaneously, we have obtained data on dive parameters similar to that produced by a con ventional tdr. while we d o not obtain a full profile for every dive, the combination of chrono logical records and hourly profiles provides all the data typically used for analysis of dive parameters (gentry & holt 1986). these data can also be linked with locations by date and time t o deter mine where the diving occurred. thus, it is poss ible to dejermine whether the animal was foraging in the water column or at the bottom. the only limitation of the sltdr compared to a conventional t d r is that it does not provide a complete record of all diving. this is related to the difficulty of transmitting all dive data to satellites during the brief times animals are ashore 110 r . l . merrick et al. 45 7 q i a i i i i i i 1 ii, i 18 20 22 local time (hr) 5 4 3 2 0 2 4 6 r h 12 14 local time (hr) l 18 20 22 70 ib local time (hr) i d c 20 0 2 4 6 mlh 10 12 14 16 18 20 22 local time (hr) fig. 3. mean dive temperature ( a ) , dive depth (b). surface interval (c). and dive duration (d) for 1216 dives made hy female steller sea lion 14080 during march 1992. and satellites are in view (around 8 minutes per hour at 55" n latitude). many more dives are reported from the histogram records (e.g., 3040 dives for animal 14080) than are reported in the chronological records (e.g., 1216 dives for animal 14080). this is because it takes much longer to transmit a comparable number of dives in the chronological record format. our strategy to deal with missing chronological and profile data is to consider the histograms as describing the total number of dives made. the chronological (and profile) records are then considered to represent a subsample of the characteristics of the total population of dives. histogram records also ensure that some data is recovered from all animals, even if they do not return to land. this makes the sltdr a powerful tool for studying wintertime foraging behavior use of satellite-linked telemetry to study steller sea lion and northern f u r seal foraging 11 1 animal 14080 8 i i i 1 i i i i 50 100 200 depth (m) 10 i i i a c ’e .p e y c c depth (m) animal 14072 5 4 3 2 . . -.--... . . -.-. ... -. ... . . . ----. . .......... -. . . i i i i 50 100 200 depth (m) c .q ! ..-.-. . . --. . . . .. a . -.. ... i i i 50 100 200 depth (m) fig. 4. distrihution of dive duration and temperature for female steller sea lions 14072 ( b & d , n = 207) and 14080 ( a & c. n = 1216) during march 1992. of fur seals and sea lions, both of whom spend prolonged periods of time at sea in the winter. incorporation of temperature sensing provides a new dimension t o analysis of these animal’s foraging ecology: inference of prey availability from the physical features of the waters foraged in. for example, some steller sea lion prey species exhibit distinct water temperature preferences. walleye pollock (theragra chalcogramma) prefer water temperatures greater than 2°c (lynde 1984). while the temperatures at foraging depth for animal 14080 (fig. 2) were above this range, many of 14072’s dives were in water below this limit. consequently, 14072 may be foraging in water where walleye pollock is not found; she may not be feeding on pollock at those times. temperature data available from the sltdr is superior in at least two ways to that presently 112 r . l . merrick et al. available to us from other sources (e.g., satellite imagery and ship-based observations). first, more temperature observations are available because the sltdr provides a relatively con tinuous record from throughout the trip. secondly, the sltdr provides in situ obser vations of actual foraging areas. temperature data are available from a conventional tdr (e.g., boyd & arnbom 1991), but they lack associated locations. in so far as animals such as sea lions and fur seals are associated with prey con centrations and oceanographic features (e.g., 4.0 i 1 i 1 '1 4.5 5.0 i ic 5.5 b i i i i 6.0 fronts), these data may also be useful to other researchers (e.g., fisheries oceanographers). acknowledgements. we are grateful to j . bengtson, r. delong, r. gentry. g . kooyman. b. mate, and w. testa for their pioneering work in the development of instruments for monitoring the diving behavior and locations of marine mammals. this research was authorized under u.s. marine mammal protection act permits 584 and 598, and special use permits issued by the u.s. fish and wildlife service's alaska maritime national wildlifc refuge. partial funding for this research was provided by ocs study mms 93-0026. our thanks to steve tracey of the u . s . department of lntcrior for his support of the research. 250 i i i i 0 200 400 600 800 1000 time from beginning of trip (min) fig. 5. dive depth (a) and temperature at depth (b) by time from beginning of trip for a trip (see fig. 1) made by female steuer sea lion 14080. point a indicates location of dive profile shown in fig. 6. times when a dive profile (open circle) or both a dive profile and a location fix (closed circle) are shown. use of satellite-linked telemetry to study steller sea lion and northern f u r seal foraging 113 fig. 6 . dive depth (a) and temperature (b) profile for a single dive of female steller sea lion 14080. this dive is shown as point a in figs. 1 and 5. c 50 h e 5 100 y 0 0" 150 200 10 20 30 40 50 references boyd, i. l. & arnbom, t. 1991: diving behaviour in relation to water temperature in the southern elephant seal: foraging implications. polar biol. 1 1 , 259-266. fancy. s. g., pank, l. f . , douglas, d. c., curby, c. h.. garner. g . w.. amstrup, s. c. & regelin. w. l. 1988: satellite telemetry: a new tool for wildlife research and man agement. u . .~. dep. inter., u . s . fish wildl. serv. resour. publ. 172. 54 pp. fowler, c. w. 1985: a n evaluation of the role of entanglement in the population dynamics of northern fur seals in the pribilof islands. pp. 291-307 in shomurd. r. s. & yoshida, h. 0. (eds.): proceedings of the workshop on the fate and impact of marine debris 27-29 november 1984, honolulu, hawaii. u.s. dep. commer., noaa tech. memo. nmfs swfc 54. gentry, r. l. & holt, j . r. 1986: attendance behavior in northern fur seals. pp. 41-78 in gentry, r. l. & kooyman. g . l. (eds.): fur seals: maternal strategies on land and at sea. princeton univ. press, princeton, nj. gentry, r. l. & kooyman, g. l. (eds.) 1986: fur seals: maternal strategies on land and at sea. princeton univ. press, princeton, nj. 291 pp. goebel, m. e., bengtson, j . l., delong, r. l., gentry, r. l., & loughlin, t . r. 1991: diving patterns and foraging locations of female northern fur seals. fish. bull., u.s. 89, 171-179. time ('20 sec) 3. temperature (c) heidi-jorgensen. m. p., stewart, b. s . & leathenvood, s. 1991: satellitc tracking of ringed seals phoca hispida off northwest greenland. holarctic ecol. i 2 , 23-29. hill, r. d.. hill, s. e. & bengtson, j. l. 1987: an evaluation of the argos satellite system for recovering data on diving physiology of antarctic seals. p. 32 in abs. of the seventh biennial conf. on the biol. of mar. mamm., miami fl. hills, s. 1987: new techniques for study of pacific walruses. p. 32 in abs. of the seventh biennial conf. on the biol. of mar. mamm., miami fl. loughlin, t . r. & merrick, r. l. 1989: comparison of com mercial harvests of walleye pollock and northern sea lion abundance in the bering sea and gulf of alaska. pp. 679 700 in proc. of the international symposium on the biology and management of walleye pollock. alaska sea grant report 89-1, loughlin, t. r. & spraker, t . 1989: use of telazol t o immobi lize female northern sea lion (eumetopias jubatus) in alaska. j . wildl. dis. 25, 353-358. loughlin, t . r., perlov, a. s. & vladimirov, v. a . 1992: range-wide survey and estimation of total abundance of steller sea lions in 1989. mar. mamm. sci. 8 , 220-229. lynde, c. m. 1984: juvenile and adult walleye pollock of the eastern bering sea: literature review and results of ecosystem workshop. pp. 43-78 in d. h. it0 (ed.): proceedings of the workshop on walleye pollock and its ecosystem in the eastern bering sea. u.s. dep. commer., noaa tech. memo. nmfs finwc-62. mate, b. r., prescott, j. & geraci, j . 1987: free-ranging 114 r . l . merrick et al. movements of a pilot whale from satellite monitored radio. abs. of the seventh biennial conf. on the biol. of mar. mamm., miami, fl. 45 pp. merrick, r. l., loughlin, t. r. and calkins. d. g. 1987: decline in abundance of the northern sea lion. eumetopias jubatus, in alaska, 1956-86. fish. bull.. u.s. 85. 351-365. service-argos. 1984: location and data collecrion system user’s guide. service-argos. toulouse, france. 36 pp. stewart. b. s.. leatherwood. s . . yochem. p. k. & heide jorgensen, m. p. 1989: harbor seal tracking and telemetry by satellite. mar. mamm. sri. 5 . 361-375. research note confrontations between humans and polar bears in svalbard ian gjertz a n d e n d r e persen gjertz, i . & persen, e . 1987: confrontations between humans and polar bears in svalbard. polar research 5 n . s . , 2 5 s 2 5 6 . since 1973 there has been a total of 50 serious confrontations between humans and polar bears in svalbard. this paper summarizes these incidents. ian gjertz, norsk polarinstitutt, p . o . box 158, n-1330 oslo lufthaun, norway; endre persen. sysselmannskontoret, 91 70 longyearbyen, norway; april 1987 (revised may 1987). svalbard is the collective name for the group of norwegian islands situated between longitudes 10" and 35"e and between latitudes 74" and 81"n. the islands have a total landmass of about 62,000 km'. national parks and nature reserves occupy 44% of svalbard's land area. svalbard has about 3500 residents, most of whom are employed in the coal mining industry. there are only three towns in svalbard. other settlements are 3 mining camps, 2 scientific stations, 2 manned weather stations and a coastal radio station. there are few trappers in svalbard, usually less than 5. besides the local residents, large numbers of tourists and many scientists visit the islands in the summer season. the norwegian government's highest re presentative is the governor (sysselmannen). he is also the chief of police, and head of nature conservation and wildlife management in the islands. by law all serious incidents of human conflicts with polar bears (ursus maritimus) have to be reported to the governor. polar bears killed in self defence are the property of the state, and such incidents are treated as a police matter. up to 1970, polar bears were hunted in large numbers throughout the islands. in july 1973 polar bears in svalbard were totally protected. since then there has been an increase in the number of polar bears and they are now quite common. according to larsen (1986), bears in east greenland, svalbard and the western soviet arctic all belong to one common discrete popu lation. he estimates that this population in 1970 numbered between 1500 and 2500 bears, and similarly that between 1980 and 1983 it had increased to between 3000 and 5000 bears. the increasing number of bears along with the increase in recreational traffic outside the inhabited areas, should presumably lead to more human contacts with polar bears. the present work summarizes contacts which have led to con flict between man and polar bear since 1973. methods conflicts between humans and polar bears in sval bard can be grouped into three categories: -bears destroying human property. this is quite common. compensations are rarely given, consequently all incidents are not reported. -bears threatening people, dogs or property. in most cases the bears are chased away with no harm being done. occasionally these incidents lead to the bear being shot. -bears killing or injuring people. this is very rare. in the present work the term 'serious con frontation' refers to the two latter categories. data have been obtained from the local news paper svalbardposten, and the governor's files. these files are mainly auction records of skins of bears killed in self defence. little or no biological data on these bears have been recorded. results since july 1973 a total of 50 cases of serious confrontations between humans and polar bears 254 i. gjertz & e. persen no. of bears i i 8 1 i i i i i i 6 1 i i i i i i i i i i 4 1 i i 1 1 i i i i m a a m i 2 1 i m m m n m 1 1 1 1 i i d i i i i i i i i 73/74 75/76 77/78 79/80 8 1 / 8 2 83/84 85/86 74/75 7 6 / 7 7 78/79 ao/ai 82/83 84/85 86/81 winter season fig / serious confrontation5 between humans and polar bears in svalbard sincc july 1973 according t o yearly winter seabons. = 1 confrontation. has been registered (fig. 1). of these cases 46 resulted in the killing of a bear and in one case a bear was wounded. but escaped. in addition three cases with human casualties are known, but in these cases no bears were killed. occurrences related to months (fig. 2) show that most incidents happen in the period decem ber-april. with a small peak in july-august. sites of confronrnrions of the 50 serious confrontations registered. 20 no. of bears 8 1 i i i 6 1 ii i i i d 1 i 4 1 iiii i n ii i i a m l m i i 1 1 1 1 ii a m 2 1 iiiii i d i d i d j f m a m j j a s o n d month fig. 2 . serious confrontations between humans and polar bears since j u l y 1973 according to months of occurrence. = 1 confrontation. occurred at manned field stations. these stations are hopen island (11). bear island (4), hornsund (4) and kapp linne (1). eight of the confrontations occurred in towns and mining camps. in four of these t h e bears were shot in self defence, while the others were shot as precautionary measures. three bears shot in or around longyearbyen were among t h e latter half. eleven polar bears a r e known killed in order to protect property. relatively few serious confrontations, 11 in all, occurred in the field. hitman casualties in only three cases since 1973 have people been injured or killed by bears. in dec. 1975 a man was attacked by a bear in barentsburg. he managed to get away by poking the bear in the eye with his thumb, but received large skin-damages t o the head and was hospitalized. in july 1977 at magdalenafjorden, northwest spitsbergen. a man was killed by a bear when he stepped o u t of his tent. in november 1978 a meteorologist at the polish polar station in hornsund was attacked by a bear. t h e bear bit him in t h e h a n d , but released him and ran when others of the crew started shooting. the man now has a permanent malfunction of the hand. t h e bear was slightly wounded in the upper neck and disappeared. confrontations between humans and polar bears in svalbard 255 occur. this is a problem that is expected to increase in the future. discussion confrontation related to year and month according to fig. 1 there are overall fewer serious confrontations today than in the seventies, in spite of the fact that both the recreational traffic and the number of bears have increased sig nificantly since 1973. this may be because people through the years have learned how to avoid confrontations, which is in contrast to the situa tion in the northwest territories, canada. according to stenhouse (1983), there was an increase in the number of nuisance bears shot in defence of life and property in the decade 1972 1981. on average 15 bears were shot yearly in the first half of the decade as opposed to 28 in the second half. in fig. 1 the year 1982/83 stands out as the exception in an otherwise general decrease in the number of confrontations. of the eight bears killed in 1982/83, four were unnecessary kill ings. two cases resulted in police charges against those who shot. most confrontations occur in the winter. december is the peak month (fig. 2). possibly because people are just as surprised every year when the first bears show up. november and december are often difficult months for hungry bears because there is usually little ice at this time of year, at least on the spitsbergen west coast where almost all of svalbard’s human inhabitants live. bears may therefore come close to settle ments either out of curiosity or in search of food. from january through april there is usually fast ice in the fiords on the spitsbergen west coast and bears are quite common. also, this period partly corresponds with the peak season for out door recreation. these two combined effects make it the period when serious confrontations most frequently occur. of the nine incidents that have occurred in the months of june, july and august (fig. 2), scientists or tourists were involved in seven. four of these cases have happened within the last five years. this may be a result of the steady increase of tourists and scientists visiting svalbard each summer. these people, unlike the locals, visit the remoter parts of svalbard, i.e. the northern and eastern parts, where bears are more common in the summer. many of these scientists and tourists are inexperienced with polar bears and therefore it is more likely that serious confrontations may sites of confrontations serious confrontations occur most frequently at hopen island, which is only inhabited by a four man meteorological crew. l0n0 (1970) showed that the, number of bears at hopen corresponds with the number of days of winter pack ice at the island, and larsen (1986) gives an account of monthly observations of bears at hopen island since 1966. bear island, lying farther south at the edge of the winter pack ice area, has a shorter period of winter pack ice and consequently has fewer bears than hopen island. hornsund has, for a few months every year, large numbers of bears passing through the area on their way to the eastern parts of the archipelago (larsen 1986; gjertz & lydersen 1986). common to all three places is that polar bears, due to winter pack ice conditions, are so numerous for parts of the year that contacts between humans and bears are more common here than in other more populated areas of sval bard. serious confrontations are therefore more likely to occur here than in other places in svalbard, all depending on the experience of the station crews. most of the bears killed as precautionary meas ures were shot in longyearbyen. this may reflect the fact that the governor resides in longyear byen, and it is also the governor who authorizes the killing of bears as precautionary measures. in other settlements local authorities first have to receive the governor’s permission before bears can be shot as precautionary measures. of the eleven bears killed protecting property, two were shot by the same man. he was a trapper protecting his dogfood. these shootings were not considered necessary and the trapper was fined. there may be several reasons why relatively few incidents occur in the field. first of all people are mostly out in the summer and late winter. in the summer bears are scarce in the western inhabitated parts of svalbard, and people visiting the more remote parts of the archipelago usually travel in boats and are therefore relatively safe. in the winter, when bears are numerous in the inhabited areas, people travel by snowmobile and are similarly quite safe. secondly, local people who travel in the wilderness are often used to 256 i . gjertz & e . persen meeting bears and know how to deal with them in a safe way. of the eleven cases of serious confrontations that have occurred in the field, six involved scientists and three tourists. biological data the governor’s files are inadequate, and d o not give much biological information on the bears killed since 1973. however, the available infor mation indicates that many of these bears were young. in the future standard biological data will be collected on all bears killed in self defence in svalbard. references gjertz. i . & lydersen. c . 1986: polar hear predation on ringed seals in the fast-ice of hornsund. svalbard. polar research 4 ( i ) . 6 6 x . larsen. t. 1986: population biology of the polar bear (ursus marifimur) in the svalhard area. n o r s k po[arinrr. s k r . 184. 55 pp. lono. 0. 1970: thc polar bear ( u r . n u maritimus phipps) in the svalbard area. h o r s k p d a r i m r . s k r . 149. 103 pp. stcnhouse. g . 1983: bear detection a n d deterrent study, cape churchill. manitoba. 1y81. n. w . t. w i d . s e r u . fi/e rep. n o . 31. 58 fp. jon y . landvik and otto salvigsen editors the ponam project in eastern svalbard preface why would the modern scienlist choose to travel to the most remote islands of the svalbard archipelago, spending days travelling, living in primitive field camps, carrying heavy equipment for long distances, and exposing himor herself to the dangers of a desolate country and its wildlife? the answer is twofold. first of all, although modern earth science relies heavily on sophisticated research techniques and laboratory studies, there will always be scientists who enthusiastically pursue the study of geology first hand, in the field. secondly, the organisation of major research programmes has made it possible for individual scientists to join larger expeditions and carry out field work in regions that require major logistics platforms. consequently, a wide range of scientific studies can be performed within the framework of common, scientific objectives. the ponam (polar north atlantic margins, late cenozoic evolution) project operated from 1990 to 1995 as part of the european science foundation (esf) arctic network. the main objective of the project was to increase our understanding of the late cenozoic history of the european arctic which borders the norwegian and greenland seas. investigations were concentrated along two major transects, one running from central greenland along the scoresby sound fjord across the continental shelf into'the deep sea, and the other running from the barents sea, across svalbard and the continental shelf into the deep sea. more than a hundred scientists and graduate students participated in the work, the majority from denmark, great britain, germany, norway and sweden. the terrestrial studies focused on the elapse of the last interglacial/glacial cycle; the field work took place in eastern greenland in 1990 and 1992, and in svalbard in 1991 and 1993. the scientific results were presented in annual internal field reports and published technical reports issued at the conclusion of the first field season in each transect (lundqua report 33 and lundqua report 3 5 ) . the final results from eastern greenland were presented in twenty papers in a special issue of boreas (no. 4, 1994). this special issue of polar research finalises the publication of the results from eastern svalbard. a synthesis of both the marine and terrestrial studies of the ponam project is scheduled to be published in a special ponam book. this volume comprises eleven papers which present results from the geological investigations of an area stretching from k o n g s ~ y a in kong karls land in the east, to b a r e n t s ~ y a and e d e g e ~ y a , and to b j ~ r n ~ y a in the south. the papers, which range in topics from weichselian stratigraphy to palaeoflora and glaciology, reflect the interdisciplinary character of quaternary studies. in an overview paper by landvik, hjort, mangerud, moller & salvigsen, the main results from the individual papers and their contribution to the quaternary history of the region are discussed. o n the basis of the extensive research presented in this volume, we expect it to become a standard reference to the quaternary development of eastern svalbard in years to come. por_001.fm 22 polar research 26 (2007) 22 – 30 © 2007 the authors blackwell publishing incmalden, usaporpolar research0800-03952007 blackwell publishing ltd? 20072612230original articles carbon and nitrogen limitation of soil microbial respirations. yoshitake et al. carbon and nitrogen limitation of soil microbial respiration in a high arctic successional glacier foreland near ny-ålesund, svalbard shinpei yoshitake, 1 masaki uchida, 2 hiroshi koizumi 3 & takayuki nakatsubo 4 1 graduate school of biosphere science, hiroshima university, japan 2 national institute of polar research, 9-10, kaga 1-chome, itabashi-ku, tokyo, 173-851 japan 3 institute for basin ecosystem studies, gifu university, gifu, 501-1193 japan 4 graduate school of biosphere science, hiroshima university, 7-1 kagamiyama 1-chome, higashi-hiroshima, 739-8521 japan abstract the hypotheses that carbon and nitrogen availability limit microbial activity, and that the key factors limiting microbes vary along the successional gradient were tested in a high arctic glacier foreland. we examined the responses of the respiration rate and the phospholipid fatty acid content to the addition of carbon and/or nitrogen. soil samples were collected from the early stage and late stage of primary succession in the foreland of a glacier near ny-ålesund, svalbard. the addition of both carbon (glucose) and nitrogen (ammonium nitrate) engendered an increase in the microbial respiration rate in the early stage of succession. in contrast, the addition of either carbon or nitrogen did not increase the microbial respiration rate. in the late stage of succession the addition of carbon alone, as well as the addition of both carbon and nitrogen, increased the microbial respiration rate. however, neither the addition of carbon nor the addition of nitrogen affected the total phospholipid fatty acid content (an index of microbial biomass) for any soil within 15 days of incubation at 10 ° c. an increase in the respiration rate was therefore attributed to changes in the physiological activities of the microbial community, such as enzymatic activity. our study suggests that microbial respiration was limited by the low availability of both carbon and nitrogen in the early stage of succession. thereafter, nitrogen limitation is mitigated. keywords high arctic; microbial biomass; microbial respiration; plfa; primary succession; substrate limitation. glacial retreat exposes new ground surfaces and provides plants and microorganisms with new habitats. in the high arctic, plant colonization takes place very slowly because it is restricted by severe environmental factors including low temperatures, a short growing season, low moisture and nutrient availability, and unstable soil structure (e.g., cryoturbation) (hodkinson et al. 2003). we can therefore observe various plant communities ranging from pioneer to later successional species along a primary successional gradient within a glacier foreland. successional changes of vegetation after glacial retreat in high arctic regions, and their relation to environmental conditions, have been studied by many ecologists (e.g., svoboda & henry 1987; minami & kanda 1995; hodkinson et al. 2003; jones & henry 2003; okitsu et al. 2004). in contrast, little information exists about soil microorganisms in a high arctic glacier foreland. soil microorganisms are known to play an important role in soil formation, and therefore in the progress of primary succession through the decomposition and mineralization of organic matter (jenkinson & ladd 1981). additionally, their function as a source and a sink of labile carbon and nutrients is of great importance (jenkinson & ladd 1981). a few studies conducted in the high arctic have shown that the microbial respiration rate and biomass are generally low in the early stages of succession and tend to increase with the progress of succession (bekku et al. 1999; bekku, kume et al. 2004; bekku, nakatsubo et al. 2004; yoshitake et al. 2006). these findings suggest that some environmental factors limit soil microbial activity and growth in the early stages of succession. correspondence shinpei yoshitake, graduate school of biosphere science, hiroshima university, 7-1 kagamiyama 1-chome, higashi-hiroshima, 739-8521, japan. email: synp@hirashima-u.ac.jp doi:10.1111/j.1751-8369.2007.00001.x s. yoshitake et al. carbon and nitrogen limitation of soil microbial respiration polar research 26 (2007) 22 – 30 © 2007 the authors 23 previous studies have shown that substrate deficiencies (especially of carbon and nitrogen) often limit microbial activity and growth in many ecosystems, including forests (joergensen & scheu 1999; vance & chapin iii 2001; ekblad & nordgren 2002; allen & schlesinger 2004), agricultural land (marschner et al. 2003; teklay et al. 2006), dry desert (schaeffer et al. 2003) and solfatara fields (yoshitake et al. 2007). the extent of this limitation apparently varies with ecosystem development. for example, aikio et al. (2000) examined the changes in soil and microbial properties in the primary succession on a post-glacial land uplift island in finland. they reported that soil microbes became increasingly nitrogen limited during the succession. this shift in limiting factors was partly explained by changes in the quality of the detritus; a higher carbon/nitrogen (c/n) ratio of the detritus was found in late stages of succession (aikio et al. 2000). yoshitake et al. (2007), who tested the substrate limitation of microbial activity and growth by amendment experiments in an acidic solfatara field, also described the shift in limiting factors with ecosystem development; microbial activity and growth were shifted from carbonand nitrogen-limited to carbon-limited. in the high arctic, the quality and quantity of organic matter and, therefore, the availability of carbon and nitrogen are expected to be different for the early and late stages of primary succession, because it is known that the composition and the coverage of vegetation varies with succession (e.g., hodkinson et al. 2003; jones & henry 2003; okitsu et al. 2004), and that plant species differ in leaf and litter quality (osono et al. 2006). therefore, it is likely that soil microorganisms are also limited by the availability of carbon and nitrogen in the early stages of succession in high arctic glacier forelands. for this study, we hypothesized that the availability of carbon and nitrogen limit microbial activity, and that key factors limiting microbes vary along the successional gradient in high arctic glacier forelands. to test these hypotheses we examined respiration rates in both the early and late stages of primary succession in a glacier foreland in svalbard, and studied the responses of the respiration rates to changes in the levels of carbon and nitrogen. the phospholipid fatty acid (plfa) content, an index of microbial biomass and community structure, was also investigated to elucidate the relationship between plfa content and the respiration rate. materials and methods study site this study was conducted at the front of austre brøggerbreen (east brøgger glacier) in ny-ålesund, northwestern spitsbergen, svalbard (79 ° n, 12 ° e; fig. 1). for the period 1995–98, the annual mean air temperature was − 5.5 ° c and the level of precipitation was 362 mm in this area (data from the norwegian meteorological institute; see uchida et al. 2002 for details). in this study, sites e and l were set up as the early and late stages of succession, respectively (fig. 1). sites e and l in this study were identical to sites 1 and 3 in some previous studies (nakatsubo et al. 1998; bekku et al. 1999; nakatsubo et al. 2005). site e was located on a newly deglaciated moraine near the tip of austre brøggerbreen. the precise chronological age of vegetation is unknown because of unpredictable disturbances in the forelands of glaciers in this area (hodkinson et al. 2003). the age of site l, roughly estimated based on geographical information, was hundreds of years or more (kume et al. 1999; bekku, kume et al. 2004). at site e, plant colonization was very limited and was restricted to isolated small plants, such as saxifraga oppositifolia l. the coverage of vascular plants was very low ( < 1%), but black soil crusts (soil surface communities consisting of algae, cyanobacteria and lichen) partially covered the ground. the ground at site l was patterned with small polygons. a mixed community of bryophytes (mainly sanionia uncinata [hedw.] loeske, hylocomium splendens [hedw.] schimp and aulacomnium turgidum figure 1 study sites in ny-ålesund, svalbard (modified from nakatsubo et al. 1998). 500 m 20 m 40 m 60 m 80 m 10 0 m site l site e a us tr e b ro gg er br ee n n sea (kolhamna) spitsbergen 15 20 25 80 78 svalbard 0 50 100 km ny-alesund 24 polar research 26 (2007) 22 – 30 © 2007 the authors carbon and nitrogen limitation of soil microbial respiration s. yoshitake et al. [wahlenb.] schwaegr.) and vascular plants (mainly salix polaris wahlenb., luzula confusa lindeb. and poa alpina l.) covered the marginal area of the polygons, whereas the central area of the polygons consisted almost entirely of bare ground. a mixed community of bryophytes and vascular plants covered about 53% of the ground, and black soil crusts covered about 30% of the ground. the remaining 17% was bare ground. a more detailed description of the vegetation at these sites is available in previous reports (nakatsubo et al. 1998; nakatsubo et al. 2005). soil sampling soil samples were collected from five points (10 cm × 20 cm) at each site in late june 2005. at site e, black soil crusts were removed with a knife and the mineral soil of the 0–5 cm layer was sampled. at site l, the parts of vascular plants and green moss standing above ground were cut and removed using scissors, then the organic soil layer (fh layer, 2.2 ± 0.5 cm thick) and mineral soil of the 0–5 cm layer (under the fh layer) were collected. plant roots and gravel in these samples were removed using a 4-mm mesh sieve and tweezers. these soil samples were stored at 4 ° c for up to 10 days after sampling until the amendment experiments were carried out. some soil properties are summarized in table 1. for this study, the water holding capacity (whc) was determined according to the definition by paul et al. (1999), which was the gravimetric water content of sieved soil that had been saturated and allowed to drain in a filter. the total carbon and nitrogen contents of the soil were measured using a cn analyser (2400 ii; perkinelmer inc., wellesley, ma, usa) and the c/n ratio was calculated. at site e, a remarkably high c/n ratio was observed (c/n = 123) because alkaline soil at this site includes carbonates (uchida et al. unpubl. data). changes in microbial respiration after the addition of carbon and nitrogen the respiration rates after the addition of either a carbon (glucose) or a nitrogen (ammonium nitrate) source, or both, were measured for 15 days (measurements were made on days 0, 2, 5, 10 and 15) to determine whether the availability of either carbon or nitrogen limits microbial respiration. we allocated five subsamples of the three soils (mineral soil of site e, and mineral and organic soils from site l) to each of four treatments: c + , the addition of a source of carbon; n + , the addition of a source of nitrogen; cn + , the addition of both a source of carbon and a source of nitrogen; and a control. a soil sample equivalent to 5 g, or 20–30 g dry weight for organic and mineral soils, was placed in a cylindrical plastic case (9 cm in diameter and 2.5 cm in height). in the c + treatment, 10 mg of glucose was added for each gram of dry soil (4 mg c g − 1 dry soil). soils in the n + treatment received table 1 soil characteristics in the sites studied. values are means ( ± se) for five replications ( n = 5). in each row values followed by the same capital letter are not significantly different (tukey–kramer test, p > 0.05). site site e site l soil layer mineral organic mineral ph (h 2 o) a 8.3 (0.08) a 6.2 (0.03) b 6.1 (0.04) b water content b 0.20 (0.03) a 1.46 (0.16) b 0.39 (0.02) a water holding capacity (whc) b,c 0.35 (0.02) a 5.36 (0.90) b 0.89 (0.06) a organic matter content (mg g − 1 dry soil) d 12 (2) a 377 (19) c 138 (11) b total carbon (mg g − 1 dry soil) e 14.3 (1.0) a 215.0 (30.8) b 66.1 (5.1) a total nitrogen (mg g − 1 dry soil) e 0.12 (0.01) a 9.34 (1.01) c 2.82 (0.17) b c/n ratio 123 (13) a 23 (2) b 23 (1) b available phosphorus (mg g − 1 dry soil) f 0.9 (0.1) a 17.1 (0.7) b 3.4 (0.7) a soil temperature ( ° c), mean (min.–max.) g − 2.2 ( − 16.3–17.9) n.d. − 3.0 ( − 13.3–17.8) dominant vegetation black soil crust (cryptogamic crust) moss ( sanionia uncinata ), salix polaris a water : soil (air-dried) = 5 : 1. b determined on 28 and 30 june 2005. c according to paul et al. (1999). d determined by loss in weight on ignition (550 ° c, 12 h). e measured with a cn analyser (2400 ii, perkinelmer inc., wellesley, ma, usa). f according to olsen & sommers (1982). g measured at a depth of 2 cm from 1 january to 31 december 2004. n.d., not determined. s. yoshitake et al. carbon and nitrogen limitation of soil microbial respiration polar research 26 (2007) 22 – 30 © 2007 the authors 25 1.1 mg of ammonium nitrate for each 1 g of dry soil (0.4 mg n g − 1 dry soil). in the cn + treatment, both glucose and ammonium nitrate were added to the soil (4 mg c + 0.4 mg n g − 1 dry soil). glucose and ammonium nitrate were added to the soils in enough water to achieve the desired water content (60% whc). for soil samples from site e, however, glucose, ammonium nitrate and water were added directly to the soil samples and mixed immediately; these soils had low whc and their initial water content (57% whc; table 1) was near the desired water content (60% whc). soils supplied only with water served as controls. all soil samples were incubated in a room where the air temperature was similar to that of field conditions (9.7 ± 4.7 ° c). the soil respiration rates (taken as co 2 emission rates) of samples were measured at 10 ± 0.3 ° c using an openflow system with an infrared gas analyser (irga; li6262; li-cor inc., lincoln, ne, usa). a detailed description of this system appeared in bekku et al. (1997). the plastic case with the sample was placed in a cylindrical chamber (9.2 cm in diameter and 3 cm in height) that was connected to the system. ambient air containing 370–385 ppm co 2 was pumped into the system at a suitable flow rate (either 100 or 300 ml min − 1 ), depending on the quantity of co 2 released from the sample. during the measurement the chamber was placed in a water bath to control the temperature. changes in plfa contents after the addition of carbon and nitrogen the soil plfa contents before and after the addition of either a carbon source (glucose) or a nitrogen source (ammonium nitrate), or both, were also determined to elucidate whether the availability of carbon and nitrogen affects the microbial biomass and community structure. the experimental design was almost identical to that for the respiration measurement (described above); plfa analyses were made on the samples on days 2, 10 and 15 after the addition of carbon and/or nitrogen sources. soil samples were freeze-dried, brought to japan, and stored at − 80 ° c until analysis. lipids were extracted using the method of bligh & dyer (1959), as modified by white et al. (1979) and frostegård et al. (1991). briefly, 1–2 g (dry weight) of soil was extracted using a chloroform methanol citrate buffer mixture (1 : 2 : 0.8). the lipids were separated into neutral lipids, glycolipids and phospholipids on a silicic acid column (sep–pak tm plus silica; waters corp., milford, ma, usa) (arao et al. 2001). the phospholipids were esterified with hcl-methanol reagent (tokyo kasei kogyo co. ltd., tokyo, japan) (stoffel et al. 1959). the resultant fatty-acid methyl esters were separated using a gas chromatograph/mass spectrometer (gc-17a/gcms-qp5000; shimadzu corp., kyoto, japan) equipped with a capillary column (phenyl– methyl/silicone (30 m db-5 ms); j&w scientific inc., folsom, ca, usa). helium was used as the carrier gas. peak areas were quantified by adding methyl nonadecanoate fatty acid (19 : 0) as an internal standard. the fatty acid nomenclature used was as described by frostegård et al. (1993). the total content of plfas (totplfas) was used to indicate the total microbial biomass (frostegård et al. 1993). we use the plfa composition as an index of microbial community structure because phospholipids are good indicators of the composition of living soil microbes (white et al. 1979). the plfas are classifiable into several categories according to their molecular structure (see peacock et al. 2001; yoshitake et al. 2006). in this study, plfas were classified into four categories (straight chain saturated fatty acids, branched chain fatty acids including cyclopropane fatty acids, unsaturated fatty acids and 18:2 ω 6); their proportions (mol%) were summed. the content of 18:2 ω 6 is known to be an indicator of fungal biomass (federle et al. 1986). previous studies have shown that this classification is useful for analyses of the shift in the microbial community structure (yoshitake et al. 2006). statistical analysis we used a repeated measures two-way anova with carbon and nitrogen as factors, and with time as the repeated factor, to test the effects of the addition of carbon and/or nitrogen on microbial respiration rates and plfa contents. we used the tukey–kramer test for multiple comparisons for each day. significance was inferred in cases where p < 0.05. results changes in microbial respiration after the addition of carbon and nitrogen for all soil samples, the respiration rate of soils with no changes (control) did not change significantly throughout the incubation period (one-way anova; p > 0.05; fig. 2). the respiration rate on day 0 in the early stage of succession (site e) was 1.0 µ g co 2 –c g − 1 h − 1 , which was almost one half of the respiration rate measured in mineral soil of the late stage of succession (site l, 1.8 µ g co 2 – c g − 1 h − 1 ). organic soil from site l had a remarkably high respiration rate (16.7 µ g co 2 –c g − 1 h − 1 ). in site e, neither the addition of carbon (c + ) nor the addition of nitrogen (n + ) increased the microbial respiration rate significantly (tukey–kramer test, p > 0.05; fig. 2a). in contrast, the respiration rates of soils with the 26 polar research 26 (2007) 22 – 30 © 2007 the authors carbon and nitrogen limitation of soil microbial respiration s. yoshitake et al. addition of both carbon and nitrogen (cn + ) increased significantly (tukey–kramer test, p < 0.05) after day 5; its highest rate was 3.1 µg co2–c g−1 h−1. in the mineral soil of site l, the respiration rate of soils with glucose (c+ and cn+) increased continuously (fig. 2b). the highest respiration rate of soil with glucose added (14.4 µg co2–c g−1 h−1) was almost seven times that of the control (tukey–kramer test, p < 0.05; fig. 2b). the addition of both carbon and nitrogen (cn+) caused a great increase in the respiration rate, with a maximum rate of 21.7 µg co2–c g−1 h−1 on day 15, which was almost 10 times that of the control respiration rate (tukey– kramer test, p < 0.05). a significant interaction was apparent for the addition of carbon and the addition of nitrogen (repeated measures two-way anova, p < 0.05). the response of microbial respiration to the added materials was much faster in the organic soil of site l (fig. 2c). on day 2, the respiration rate of soils with glucose added (c+ and cn+) had already reached 62.0– 63.8 µg co2–c g−1 h−1, which was almost three times that of the control (tukey–kramer test, p < 0.05). however, in both the c+ and cn+ treatments, the respiration rate decreased gradually and no significant differences among treatments were detected on day 15 (tukey–kramer test, p > 0.05). the addition of nitrogen (n+) did not raise the respiration rate and no significant interaction was observed for the addition of carbon and nitrogen (repeated measures two-way anova, p > 0.05). changes in plfa contents after the addition of carbon and nitrogen for all soil samples, the totplfas content and the plfa composition in the control treatment did not change significantly throughout the incubation period (one-way anova, p > 0.05; fig. 3). the totplfas content for site e on day 2 was 31 nmol g−1, which was lower than the totplfas in the mineral and organic soils from site l (211 and 1013 nmol g−1, respectively). however, if totplfa contents are compared on a unit per gram of soil organic matter (som) basis instead of per gram of soil, the totplfas from site e, from mineral soil from site l and from organic soil from site l would be 2.2, 1.6 and 2.9 nmol mg−1 som, respectively, and no significant difference would be inferred (one-way anova, p > 0.05). the respective plfa compositions of control treatments figure 2 effects of the addition of glucose (c+) and ammonium nitrate (n+) on the soil microbial respiration rate of (a) site e, (b) mineral soil from site l and (c) organic soil from site l. vertical bars represent ± se (n = 5). 0 5 10 15 0 5 10 15 control c+ n+ cn+ m ic ro b ia l r e sp ir a tio n r a te ( µ g c o 2 -c g -1 h -1 ) time after addition (days) (a) site e 0 10 20 30 0 5 10 15 control c+ n+ cn+ m ic ro b ia l r e sp ir a tio n r a te ( µ g c o 2 -c g -1 h -1 ) time after addition (days) (b) site l mineral soil 0 30 60 90 0 5 10 15 control c+ n+ cn+ (c) site l organic soil time after addition (days) m ic ro b ia l r e sp ir a tio n r a te ( µ g c o 2 -c g -1 h -1 ) s. yoshitake et al. carbon and nitrogen limitation of soil microbial respiration polar research 26 (2007) 22 – 30 © 2007 the authors 27 were also different among study sites: the proportion of branched chain fatty acids at site e was lower than the proportion found in the mineral and organic soils of site l; the organic soil from site l had a higher proportion of unsaturated fatty acids than the levels found in the other two soils. in site e, throughout the incubation period, no significant differences were detected in the totplfa contents among treatments (tukey–kramer test, p > 0.05; fig. 3a). in mineral soil from site l, the totplfa content of soils with added carbon (c+ and cn+) were slightly higher than the totplfa content of the control (fig. 3b). however, no significant differences were detected in the totplfa content between the treatments (tukey–kramer test, p > 0.05). in addition, in organic soil from site l the addition of carbon and/or nitrogen did not alter the totplfa content significantly (tukey–kramer test, p > 0.05; fig. 3c). in most cases, the addition of carbon and/or nitrogen had little effect on plfa composition. at site e, however, the proportion of unsaturated fatty acids in soils with both carbon and nitrogen added (cn+) was slightly higher than that in the control on day 15 (tukey–kramer test, p < 0.05). furthermore, in mineral and organic soils from site l, similar differences were observed on day 10 (tukey–kramer test, p < 0.05). in addition, in organic soil from site l, the proportion of branched chain fatty acids in the c+ and cn+ treatments was significantly lower than that of the control on day 10 (tukey–kramer test, p < 0.05). discussion the microbial respiration rates of the mineral soil in the early stage of primary succession (site e) in a glacier foreland in ny-ålesund were lower than the respiration rates in the late stage of succession (site l). the respiration rate of untreated soil from site e (1.0 µg co2–c g−1 h−1) was similar to values reported previously from that site (bekku, nakatsubo et al. 2004), from other glacier foreland areas (schipper et al. 2001) and from a cold antarctic desert (ino et al. 1980). the respiration responses to the addition of carbon and nitrogen were different between the early and late stages of succession, and between organic and mineral soils. in the early stage of primary succession in a high arctic glacier foreland (site e), single additions of carbon (c+) and nitrogen (n+) had little effect on the microbial figure 3 effects of the addition of glucose (c+) and ammonium nitrate (n+) on the total phospholipid fatty acids content (totplfas) of (a) site e, (b) mineral soil from site l and (c) organic soil from site l. vertical bars represent ± se (n = 3). 0 100 200 300 400 500 2 10 15 control c+ n+ cn+ p l fa c o n te n t (n m o l g -1 ) time after addition (days) (a) site e 0 100 200 300 400 500 2 10 15 control c+ n+ cn+ time after addition (days) (b) site l mineral soil p l fa c o n te n t (n m o l g -1 ) 0 500 1000 1500 2 10 15 control c+ n+ cn+ time after addition (days) (c) site l organic soil p l fa c o n te n t (n m o l g -1 ) 28 polar research 26 (2007) 22 – 30 © 2007 the authors carbon and nitrogen limitation of soil microbial respiration s. yoshitake et al. respiration rate (fig. 2a). in contrast, the respiration rate of soils with both carbon and nitrogen (cn+) added increased for about 15 days. these results suggest that heterotrophic microbial activity (soil respiration rate) in the early stage of primary succession in a high arctic glacier foreland is limited by twin deficiencies of carbon and nitrogen. previous studies reported that carbon was the primary limiting factor of microbial activity and/or growth, and that nutrients such as nitrogen and phosphorus were co-limiting factors in many ecosystems ranging from arctic tundra to tropical forests (michelsen et al. 1999; schmidt et al. 2000; ekblad & nordgren 2002; sørensen et al. 2006; tekley et al. 2006). in this study, however, no significant difference in the microbial respiration was detected between the c+ and control samples, although the mean value of respiration rate in the c+ treatment was slightly higher than that in the control (fig. 2a). therefore, it was difficult to determine whether carbon was the primary limiting factor of microbial activity in the early stage of primary succession. in the mineral soil of site l, the addition of carbon (c+) alone as well as the addition of both carbon and nitrogen (cn+) increased the microbial respiration rate significantly (fig. 2b). that is, the addition of glucose stimulated the respiration rate of the mineral soil from site l despite the fact that the soil possessed substantial concentrations of total carbon (table 1). this fact suggests that the respiration rate was limited primarily by a deficiency of a labile carbon substrate. a considerable fraction of heterotrophic respiration is thought to arise from the decomposition of an active but small labile carbon pool (townsend et al. 1997; biasi et al. 2005). smith (2005) also reported this type of limitation of the soil microbial respiration rate in a sub-antarctic ecosystem. interaction between carbon and nitrogen was observed in this study, indicating that nitrogen availability in the mineral soil from site l was also insufficient to utilize the added labile carbon source. in contrast, for the organic soil of site l, neither the addition of nitrogen alone (n+) nor the addition of nitrogen and carbon in combination (cn+, for an interactive effect) showed any effect on the microbial respiration rate (fig. 2c), suggesting that the rate was not limited by nitrogen availability. in contrast, the addition of carbon (c+ and cn+) also triggered a significant increase in the microbial respiration rate in the organic soil from site l, indicating that the microbial respiration rate in the organic soil of site l was also limited by labile soil carbon. however, the response pattern observed in organic soil differed somewhat from that in mineral soil; the rates of increase in carbon addition were much higher in the organic soil and a gradual decrease in the respiration rate was observed at 5–15 days after treatment. this decrease was attributable to the consumption of an additional substrate by soil microbes. in the organic soil from site l, the quantities of excess carbon emitted as co2 from c+ and cn+ soils from 2 to 15 days after treatment, as calculated by subtracting the quantity of co2–c in the control from the co2–c in the c+ and cn+ treatments, were 7.6 and 6.0 mg g−1 (191% and 150% of the carbon added), respectively (calculated from data shown in fig. 2c). we conclude, therefore, that a large proportion of the carbon from glucose was consumed by 15 days after the treatment. in addition, these results might indicate that the treatment of a labile carbon substrate promoted the utilization of a native carbon substrate. in contrast to the respiration rate, the microbial biomass was not affected significantly by the addition of either carbon or nitrogen, or by the addition of both (fig. 3). the increase in respiration rates without the increase in microbial biomass indicates changes in the physiological activities of microbial communities such as enzymatic activity. both in short-term and the long-term experiments, the addition of organic matter often engenders increased enzyme activities (kandeler et al. 1999; crecchio et al. 2001; marschner et al. 2003). in addition, joergensen & scheu (1999) suggested that the ratio between the active and the dormant parts of the microbial biomass was changed either by the activation of dormant microorganisms or by a change in their metabolic activity after treatment. in this study a small shift in the microbial community structure was observed, which might also affect the respiration rate without increasing microbial biomass. the insensitivity of microbial growth to the addition of carbon and/or nitrogen observed in this study was different from the result reported for a solfatara field surrounding a fumarole (volcanic vent) (yoshitake et al. 2007). in the solfatara field, the addition of similar quantities of carbon and/or nitrogen as those used in this study triggered a remarkable two–three-fold increase in the microbial biomass during a 15-day incubation at 25°c (yoshitake et al. 2007). however, this insensitivity of microbial growth to the addition of carbon and/or nitrogen does not necessarily contradict the importance of som for the microbial biomass in the high arctic. in this study, the values of totplfas/som were similar, irrespective of the successional stage, suggesting that som is an important factor for determining the soil microbial biomass. therefore, the accumulation of som through successional progress would engender an increase in the microbial biomass. in conclusion, although the microbial respiration rate in the high arctic glacier foreland that we studied was limited by carbon and nitrogen availability, the extent of that limitation differed among successional stages and s. yoshitake et al. carbon and nitrogen limitation of soil microbial respiration polar research 26 (2007) 22 – 30 © 2007 the authors 29 between organic and mineral soils. especially in the early stage of primary succession, low availabilities of both carbon and nitrogen were important limiting factors of the microbial respiration rate. acknowledgements we thank mr y. mouri, of the natural science center for basic research and development (n-bard), hiroshima university, for measuring the carbon and nitrogen contents of samples. this study was supported by a grant-inaid for scientific research of the japan society for the promotion of science. references aikio s., väre h. & strömmer r. 2000. soil microbial activity and biomass in the primary succession of a dry heath forest. soil biology and biochemistry 32, 1091–1100. allen a.s. & schlesinger w.h. 2004. nutrient limitations to soil microbial biomass and activity in loblolly pine forests. soil biology and biochemistry 36, 581–589. arao t., okano s. & nishio t. 2001. comparison of bacterial and fungal biomass determined by phospholipid fatty acid and direct microscopical analysis in 4 types of upland soils. soil microorganisms 55, 29–36. bekku y., koizumi h., oikawa t. & iwaki h. 1997. examination of four methods for measuring soil respiration. applied soil ecology 5, 247–254. bekku y., kume a., nakatsubo t., masuzawa t., kanda h. & koizumi h. 1999. microbial biomass in relation to primary succession on arctic deglaciated moraines. polar bioscience 12, 47–53. bekku y.s., kume a., masuzawa t., kanda h., nakatsubo t. & koizumi h. 2004. soil respiration in a high arctic glacier foreland in ny-ålesund, svalbard. polar bioscience 17, 36–46. bekku y.s., nakatsubo t., kume a. & koizumi h. 2004. soil microbial biomass, respiration rate, and temperature dependence on a successional glacier foreland in ny-ålesund, svalbard. arctic, antarctic, and alpine research 36, 395–399. biasi c., rusalimova o., meyer h., kaiser c., wanek w., barsukov p., junger h. & richter a. 2005. temperaturedependent shift from labile to recalcitrant carbon sources of arctic heterotrophs. rapid communications in mass spectrometry 19, 1401–1408. bligh e.g. & dyer w.j. 1959. a rapid method of total lipid extraction and purification. canadian journal of biochemistry and physiology 37, 911–917. crecchio c., curci m., mininni r., ricciuti p. & ruggiero p. 2001. short-term effects of municipal solid waste compost amendments on soil carbon and nitrogen content, some enzyme activities and genetic diversity. biology and fertility of soils 34, 311–318. ekblad a. & nordgren a. 2002. is growth of soil microorganisms in boreal forests limited by carbon or nitrogen availability? plant and soil 242, 115–122. federle t.w. 1986. microbial distribution in soil—new techniques. in f. megusar & m. gantar (eds.): perspectives in microbial ecology. pp. 493–498. ljubljana: slovene society for microbiology. frostegård å., tunlid a. & bååth e. 1991. microbial biomass measured as total lipid phosphate in soils of different organic content. journal of microbiological methods 14, 151–163. frostegård å., tunlid a. & bååth e. 1993. phospholipid fatty acid composition, biomass, and activity of microbial communities from two soil types experimentally exposed to different heavy metals. applied and environmental microbiology 59, 3605–3617. hodkinson i.d., coulson s.j. & webb n.r. 2003. community assembly along proglacial chronosequences in the high arctic: vegetation and soil development in north-west svalbard. journal of ecology 91, 651–663. ino y., oshima y., kanda h. & matsuda t. 1980. soil respiration in the vicinity of syowa station, antarctica 1. relationships between soil respiration rate and water content or nitrogen content. antarctic record 70, 31–39. jenkinson d.s. & ladd j.n. 1981. microbial biomass in soil: measurement and turnover. in e.a. paul & j.n. ladd (eds.): soil biochemistry. pp. 415–471. new york: marcel dekker. joergensen r.g. & scheu s. 1999. response of soil microorganisms to the addition of carbon, nitrogen and phosphorus in a forest rendzina. soil biology and biochemistry 31, 859– 866. jones g.a. & henry g.h.r. 2003. primary plant succession on recently deglaciated terrain in the canadian high arctic. journal of biogeography 30, 277–296. kandeler e., stemmer m. & klimanek e.m. 1999. response of soil microbial biomass, urease and xylanase within particle size fractions to long-term soil management. soil biology and biochemistry 31, 261–273. kume a., nakatsubo t., bekku y. & masuzawa t. 1999: ecological significance of different growth forms of purple saxifraga, saxifraga oppositifolia l., in the high arctic, nyålesund, svalbard. arctic, antarctic, and alpine research 31, 27–33. marschner p., kandeler e. & marschner b. 2003. structure and function of the soil microbial community in a long-term fertilizer experiment. soil biology and biochemistry 35, 453– 461. minami y. & kanda h. 1995. bryophyte community dynamics on moraine at deglaciated arctic terrain in ny-ålesund, spitsbergen (in japanese with english summary). proceedings of the bryological society of japan 6, 157–161. michelsen a., graglia e., schmidt i.k., jonasson s., sleep d. & quarmby c. 1999. differential responses of grass and a dwarf shrub to long-term changes in soil microbial biomass c, n and p following factorial addition of npk fertilizer, fungicide and labile carbon to a heath. new phytologist 143, 523–538. nakatsubo t., bekku y., kume a. & koizumi h. 1998. respiration of the belowground parts of vascular plants: its contribution to total soil respiration on a successional glacier foreland in ny-ålesund, svalbard. polar research 17, 53–59. 30 polar research 26 (2007) 22 – 30 © 2007 the authors carbon and nitrogen limitation of soil microbial respiration s. yoshitake et al. nakatsubo t., bekku y.s., uchida m., muraoka h., kume a., ohtsuka t., masuzawa t., kanda h. & koizumi h. 2005. ecosystem development and carbon cycle on a glacier foreland in the high arctic, ny-ålesund, svalbard. journal of plant research 118, 173–179. okitsu s., sawaguchi s., hasegawa h. & kanda h. 2004. vegetation development on the glacier moraines in oobloyah valley, ellesmere island, high arctic canada. polar bioscience 17, 83–94. olsen s.r. & sommers l.e. 1982: phosphorous soluble in sodium bicarbonate. in: a.l. page et al. (eds.): methods of soil analysis, part 2, chemical and microbiological properties. 2nd edn. pp. 421–422. madison, wi: american society of agronomy. osono t., mori a., uchida m. & kanda h. 2006. chemical property of live and dead leaves of tundra plant species in oobloyah valley, ellesmere island, high arctic canada. memoirs of national institute of polar research, special issue 59, 144–155. paul e.a., harris d., klug m.j. & ruess r.w. 1999. the determination of microbial biomass. in: g.p. robertson et al. (eds.): standard soil methods for long-term ecological research. pp. 291–317. new york: oxford university press. peacock a.d., mullen m.d., ringelberg d.b., tyler d.d., hedrick d.b., gale p.m. & white d.c. 2001. soil microbial community responses to dairy manure or ammonium nitrate applications. soil biology and biochemistry 33, 1011– 1019. schaeffer s.m., billings s.a. & evans r.d. 2003. responses of soil nitrogen dynamics in a mojave desert ecosystem to manipulations in soil carbon and nitrogen availability. oecologia 134, 547–553. schipper l.a., degens b.p., sparling g.p. & duncan l.c. 2001: changes in microbial heterotrophic diversity along five plant successional sequences. soil biology and biochemistry 33, 2093–2103. schmidt i.k., ruess l., bååth e., michelsen a., ekelund f. & jonasson s. 2000: long-term manipulation of the microbes and microfauna of two subarctic heaths by addition of fungicide, bactericide, carbon and fertilizer. soil biology and biochemistry 32, 707–720. smith v.r. 2005. moisture, carbon and inorganic nutrient controls of soil respiration at a sub-antarctic island. soil biology and biochemistry 37, 81–91. sørensen l.i., holmstrup m., maraldo k., christensen s. & christensen b. 2006. soil fauna communities and microbial respiration in high arctic tundra soils at zackenberg, northeast greenland. polar biology 29, 189–195. stoffel w., chu f. & ahrens jr e.h. 1959. analysis of long-chain fatty acids by gas-liquid chromatography. micromethod for preparation of methyl esters. analytical chemistry 31, 307–308. svoboda j. & henry g.h.r. 1987. succession in marginal arctic environments. arctic and alpine research 19, 373–384. teklay t., nordgren a. & malmer a. 2006. soil respiration characteristics of tropical soils from agricultural and forestry land-uses at wondo genet (ethiopia) in response to c, n and p amendments. soil biology and biochemistry 38, 125–133. townsend a.r., vitousek p.m., desmarais d.j. & tharpe a. 1997. soil carbon pool structure and temperature sensitivity inferred using co2 and 13co2 incubation fluxes from five hawaiian soils. biogeochemistry 38, 1–17. uchida m., muraoka h., nakatsubo t., bekku y., ueno t., kanda h. & koizumi h. 2002. net photosynthesis, respiration, and production of the moss sanionia uncinata on a glacier foreland in the high arctic, ny-ålesund, svalbard. arctic, antarctic, and alpine research 34, 287–292. vance e.d. & chapin iii, f.s. 2001. substrate limitations to microbial activity in taiga forest floors. soil biology and biochemistry 33, 173–188. white d.c., davis w.m., nickels j.s., king j.d. & bobbie r.j. 1979. determination of the sedimentary microbial biomass by extractable lipid phosphate. oecologia 40, 51–62. yoshitake s., sasaki a., uchida m., funatsu y. & nakatsubo t. 2007. carbon and nitrogen limitation to microbial respiration and biomass in an acidic solfatara field. european journal of soil biology 43, 1–13. yoshitake s., uchida m., nakatsubo t. & kanda h. 2006. characterization of soil microflora on a successional glacier foreland in the high arctic on ellesmere island, nunavut, canada using phospholipid fatty acid analysis. polar bioscience 19, 73–84. research note observations of walrus (odobenus rosmarus rosmarus) in the southeastern barents and pechora seas in february 1993 tore haug and h e l l tormod nilssen haug, t. & nilssen, k . t. 1995. observations of walrus ( o d o b e n w rosmarw rosmarus) in the southeastern barents and pechora seas in february 1993. polar research 14(1), 83-86. a total of 138 walruses (odobenus rosmarus rosmarus), including 21 cow/calf pairs, were observed during a ship-board survey in the southeastern barents and pechora seas 5-17 february 1993. the observations confirm these areas as wintering and nursery grounds for the species. t. haug and k . t . nilssen, norwegian institute of fisheries and aquaculrure, p . o . box 2511, n-900-7 trams@, norway. introduction the distributional area of the atlantic walrus (odobenus rosrnarus rosmarus) ranges from the central and eastern canadian arctic in the kara sea, with several more or less well-defined sub populations or stocks within this range (reeves 1978; born et al. 1995). one such subpopulation or stock is confined, at least periodically, to the southeastern barents sea and the white and pechora seas (belborodov & timosenko 1974; timosenko 1984; popov et al. 1990). as surveys to determine distribution and size of walrus populations in the russian arctic have not been conducted during the recent years, no comprehensive population figures are available (born et al. 1995). at different periods of the year in 199c-1993, several expeditions with the objective of catching catch harp seals (phoca gro enlandica) for ecological studies were carried out in the barents sea and adjacent waters (nilssen in press). observations of other marine mammals were recorded systematically during all these expeditions. during an expedition conducted in the southeastern barents arid the pechora seas in february 1993 (nilssen 1995), particularly many walruses were observed. these observations are summarised in this note. expedition route and dates the expedition used the norwegian ice-going research vessel r/v jan mayen and was con ducted along the edges of the pack-ice belt in the southeastern parts of the barents sea between cape kanin and novaja zemlja during the period 5-17 february 1993 (fig. 1). the expedition began in the areas west of kolguev (5-7 february), proceeded with activities in the pechora sea (8-9 and 11 february, with an inter mediate trip northwards along novaja zemlja on 10 february), and terminated with new opera tions between cape kanin and kolguev during the period 13-17 february. whenever daylight permitted, continuous observations of marine mammals (including walruses) were performed both from the wheelhouse and, occasionally, from a barrel on the wheelhouse roof. all animal obser vations made either by scientists or by the crew of the vessel were recorded systematically. walrus observations a total of 138 walruses (including 21 cow/calf pairs) were observed during the whole survey (fig. i , table 1). during the period 5-7 february, 84 t. haug & k . t. nilssen 4 t 7 2 0 0 7 1 0 0 7 0 0 0 6 9 0 0 6 8 0 0 6 7 0 0 b a r e n t s s e a pechora s e a guljaevskie koski russia 7 2 0 0 ? 1 0 0 7 0 0 0 6 q o o 6 8 0 0 6 7 0 0 fig. 1. t h c k \ j.%h m a ’ ~ f ’ ~ surve! track (xilid line) and t h e localltie5 of\valrua ohservations (black dots. indicating pairs of cows,’ calve\. sinplc a n i m a l s o r g r o u p \ of animal\) i n t h e southeastern b a r e n t \ and t h e pechora seas 5-17 fehrunry 1993. 13 animals were seen in the area to the west of kolguev. east and northeast of this island 18 walruses were observed from 8 to i 1 february. upon return to the areas between cape kanin and kolguev on 12 february. the edge of the pack ice area was contined to areas within russian territorial waters (1.e.. within 12 nm from the coastline) where no operations by the norwegian research vessel were permitted. favourable cur rent and wind conditions. however. moved the pack ice outside the 1 2 rim limit again. and the expedition was able to carry o n its investigations. during the period 13-17 february, 107 walruses were observed in these western areas. all animals were observed within the pack-ice area. mainly resting on ice-floes. occasionally also swimming in the water. acoustically recorded depths in the areas of walrus observations were xb65 rn west of kolguev. 5@75 m in the pechora sea. and 10ck140 ni west of novaja zemlja. the observed calves were small. without visible tusks, and undoubtedly defended by their mothers. ani observations of walrus (odobenus rosmarus rosmarus) 85 mals without calves were usually single individ uals, but a few groups of 3-5 animals also occurred. discussion according t o popov e t al. (1990) walruses occur in the southeastern part of the barents sea throughout the year, though their numbers are small. t h e february 1993 observations of walrus between c a p e kanin and novaja zamlja pre sented here are consistent with previous obser vations stating that the species winters in the southeastern parts of the barents sea, in par ticular the areas between t h e white sea and the kolguev island, where the walruses habitually occur in january-february (beloborodov & timosenko 1974; timosenko 1984). regular occurrences of walruses during spring (march april) in the white sea, possibly reflecting an inclination of the animals to return to their former habitat, have been recorded during the past 10 20 years (timosenko 1984; popov e t al. 1990). t h e southeastern barents sea wintering areas of the walruses is coalescent both in time and space with the route of harp seals migrating along the ice edge to their white sea breeding grounds. timosenko & popov (1990) suggest that this may have contributed t o the movement of certain walruses in t h e white sea where they have been observed t o kill and feed upon harp seals. par ticularly pups. the many cow/calf observations indicate that the surveyed areas may serve as nursery grounds for t h e walruses during winter. in aerial surveys in january 1977. several walruses, including females accompanied by small calves o n ice floes with blood spots, were observed between islands of the guljaevskie koski archipelago (fig. 1); possible habitual whelping of the species on these grounds in late december-early january was suggested (lukin 1978). from satellite telemetry experiments there is some evidence of a common svalbard-franz josef land stock of walruses (gjertz & wiig 1994). t h e true connection between walruses inhabiting these northern archipelagos and other areas within or adjacent to the barents sea (including those wintering in the southeastern barents and pechora seas) is, however, virtually undeter mined (born 1984; born et al. 1995). little is known about the current status of walruses along the russian coast. lukin (1978). from his january 1977 observations, stated that the total number of walruses wintering in the southeastern barents sea apparently did not exceed 10cl120 heads. t h e present survey was not designed to estimate the number of walruses; for instance, it did not cover areas within russian territorial waters. however, it is worth noting that the total number of observed animals (13s) exceeds the wintering stock size suggested by lukin (1978). walruses a r e encountered in the southeastern barents and pechora seas also during spring and summer. and observations of herds counting approximately 100 animals were made south and west of the vajgae island in june-july both in 1970,1971 (timosenko 1984) and 1988 (popov e t al. 1990). acknowledgernents. -thanks are due to crew and field assistants onboard r/v jan mayen. to s. hartvedt and l. olsen for technical assistance, and to 0. wiig for comments on the manuscript. the harp seal expedition was supported by funding from the norwegian council for research, project no. 1(14511/ 110. references beloborodov, a . g . & timosenko, j . k. 1y74 (1976): zaseitu atlantieeskogo moria (in defence of the atlantic walrus). priroda 1974(3), 97-99 (tratul. ser. mar. sero. can. 3 1 b . 7 born, e. w. 1984: status of the atlantic walrus odobenus rosmarus in the svalbard area. polar reseurch 2 1 1 , s . . 27-45. born, e. w., gjertz, 1. & reeves, r . r. 1995: population assessment of atlantic walrus (odobenus rosmarus rosmaru l . ) . rep. nammco sc meeting, copeidragen 31 january 2 februaty 1995. 104 pp. gjertz, i . & wiig, 0. 1994: past and present distribution of walruses in svalbard. arcric 47, 34-42. lukin, l. r. 1978: 0 srokach i rajonach seenki atlantiteskogo moria (time and regions of whelping of the atlantic walrus). ekologija 5 . 1oc-101 (translated. north division. n . m. knipovich polar marine fisheries institute. 2 pp.). nilssen. k. t. 1995: seasonal distribution. condition and feed ing habits of barents sea harp seals (phoca groenlandicu). pp. 241-254 in blix, a . s . . ulltang, 0. & walloe, l (eds): whales, seals, fish and man. elsevier science bv. nilssen, k. t . , ahlqvist. i . , eliassen. j.-e., haug, t. rr lind blom, l . 1994: studies of food availabiljty and diet of harp seals (phoca groenlandica) in the southeastern barents sca in february 1993. ices cm 1994/n:12. 24 pp. popov, l . , timosenko, j . k . & wiig, 0. 1990: review of history and present status of world walrus stocks barcnts. kara and white seas. pp. 6-14 in fay. f. h . . kelly, b. p. &r fay, b. a . (eds): t/ie ecology and managemenl of wulrus populations. report of an international workshop. 26-30 march 1990. seattle, washington. u s a . marine mammal commission report fby1-100479. pp.). 86 t . haiig & k . t . nilssen reeves. r . r . iy78: atlantic walrus (odohrnus rostnurus ros murus). a literature survey and status report. us depr. lnrerior u’ddlije rra. rep. 10 4 1 pp timosenko. ju. k. 1984: concerning the protection and res toration of the western atlantic population of the walrus. pp. lo(k103 i n yablokov. a. v . ( e d . ) . marrnr mu?nmol.~. nauka. moscow ( i n russian. transl. by f h . fa! 1983). timobenko. ju. k. & popov. l . a . 1990: on the predatory habits of atlantic walrus. pp. 177-178 in fay, f. 11.. kelly, b. p . & fay. b . a . (eds): the ecology m d munngewient of nulrus populariom. report of an international workshop, 2g30 march 1990. seattle. washington. u s a . marine mam mal commission report fb91-100479. driftwood as an indicator of relative changes in the influx of arctic and atlantic water into the coastal areas of svalbard 6 l a f u r eggertsson eggertsson, 6 . 1994: driftwood as an indicator of relative changes in the influx of arctic and atlantic water into the coastal areas of svalbard. polar research 13(2), 209-218. a total of 276 driftwood samples from wijdefjorden on the northern coast of spitsbergen were den drochronologically analysed and compared with results from a similar study on driftwood from isfjorden. the composition and origin of the driftwood from the two places differ. whereas larix is almost absent in the isfjorden driftwood, it comprises 25% of the wijdefjorden collection. the isfjorden driftwood has its main origin in the white sea region and the dates of the driftwood concentrate around the period from 1950 to 1979, with only a few dates from the period 1910 t o 1950. the wijdefjorden driftwood has two main origins: siberia and the white sea region. the dates of the white sea components of the wijdefjorden driftwood are concentrated mainly in the period 1910-1950. the dates of the siberian (yenisey) components of the wijdefjorden driftwood are concentrated in the period 1950-1979. it can be argued that during the time period from ca. 1910 to 1950 the activity of a warm northerly flowing current along the western coast of spitsbergen was stronger, transporting white sea driftwood au the way to the wijdefjorden area. however, after ca. 1950 the input of white sea driftwood decreased, and the relative importance of the siberian component increased. these results fit well with the climatic records from svalbard, showing a warm regime during the first half of this century due to increased activity of the warm west spitsbergen current along the western coast of spitsbergen. after ca. 1950, the influx of atlantic water became weaker, the climate became colder and the relative occurrences of siberian driftwood transported by the transpolar current increased on the northern coast of the svalbard archipelago. 61afur eggerfsson, departmen: of quaternary geology. lund university, tornavagen 13, s-223 63 lund. sweden introduction svalbard is situated in a climatically sensitive area between the relatively warm atlantic waters (a branch of the norwegian coastal current) and the cold arctic waters. the climatic variation in the svalbard area depends mainly on the activity and properties of the atlantic water flowing into the barents sea and up along the western side of the archipelago (loeng 1989). some boreal mollusc species, which are now extinct in svalbard, are found in raised beach deposits, indicating changes in sea surface tem peratures during the holocene (e.g. feyling hanssen 1955). recent studies by salvigsen et al. (1992) and hjort et al. (1992) on the paleoclimatic implications of the changing mollusc fauna in svalbard, indicate the absolute age for the holo cene marine climatic optimum on svalbard t o be from circa 9500 to 3500 radiocarbon years bp. during this time period, mytilus edulis lived o n svalbard. climatic variations in the svalbard area during this century have been recorded in tem perature and salinity sections crossing the water masses flowing into the barents sea. temperature anomalies in a section from the kola peninsula along 33"30'e show that the longest period with a warm regime of inflowing atlantic water during this century was between 1930 and 1939, with a maximum in 1938. the years after 1945 were characterised by temperature fluctuations of 3-5 years duration (midttun et al. 1981). instrumental climatic records from svalbard (fig. 1) mirror the same changes, with a conspicuously warm period between 1920 and 1950 and a cooling trend with some fluctuations after that. climatic records from stations in the arctic and from other part of the northern hemisphere during this century show similar trends (fig. 2) (kelly et al. 1982). driftwood is present on many beaches in the arctic, originating from the boreal forest regions of russia, alaska and canada. northward flow ing rivers which drain the forest areas carry huge quantities of driftwood into the arctic ocean 210 0. eggertsson n , b j r m r y a isflord radio oc -6 -1 0 4 1900 1920 1940 1960 1980 2000 year ad fig. 1 . annual mean temperatures ("c) at bjqrnbya, lsfjord radio and hopen svalbard, smoothed by five-year running averages. data from dnmi. i : 1880 1900 1920 1940 1960 1980 1.0 b i -2.0 t fig. 2. annual mean temperatures ("c) as departures from the reference period 1940-1960 averaged over (a) the northern hemisphere (0-85"n) and (b) the arctic (65-85"n) (modified from kelly et al. 1982). (fig. 3). the wood either derives from living forests, undercut by rivers, or from logs which have come loose during timber floating. the wood is caught in drifting ice, transported by ocean currents, and eventually deposited along the shores of the arctic. (e.g. kindle 1921; eurola 1971; haggblom 1982; bartholin & hjort 1987; eggertsson 1992). most driftwood is caught in drifting ice and transported by ocean currents. therefore it is important to have a clear view of the general characteristics of sea surface circulation in the arctic basin. the main features are the beaufort sea gyre and the transpolar current. the transpolar cur rent carries ice from the eastern part of the siber ian sea and the bering strait, across the north pole area and down along the east coast of green land (fig. 3). the average speed of the transpolar current is nearly constant over a distance of 2000 2500 km in the polar basin and has been estimated to be 2.8 cm/s (2.4 km/day). when it passes the narrowest part of the fram strait it is close to 9.5 cm/s (8.2 km/day) (fig. 4) (vinje 1982). from this, the transportation time for wood drifting from the siberian coast to the fram strait is esti mated to be more than three years. along the western coast, the norwegian coastal current brings in relatively warm high-salinity water (lunde 1963). agardh (1869) is considered as the pioneer of driftwood studies. he demonstrated that his material, 18 samples collected in svalbard, was of siberian origin. he also used the tree rings to deduce the climatic conditions under which the trees had grown. agardh's methods were later taken up by ortenblad (1881) and ingvarson (1903, 1910). haggblom (1982) estimated the amount and type of driftwood logs on raised beaches at different elevations above the present sea level on the island of hopen, svalbard (fig. 5). he concluded that variations in the driftwood frequency probably reflected variations in sea ice conditions over time, and that the period between 9000 and 4200 bp was characterised by moderate sea-ice conditions due to long summers. haggblom's idea was based on the fact that wood floating in open water has limited buoyancy and will sooner or later sink. thus, much driftwood should indicate much drift ice. giddings (1941) was the first to apply the den drochronological method to driftwood. he wor ked with dendrochronological studies in alaska and noticed that the tree-ring record at timberline did not change rapidly from one locality to another. he assumed that cross-dating was appli cable to dead logs. he realised the possibility of using the driftwood dates as an aid in mapping map currents in the arctic region. later giddings (1943) detected that logs found on the alaskan coast of the beaufort sea had a tree-ring pattern driftwood us an indicator of relative changes 211 fig. 3. surface currents in the arctic ocean (current pattern from strubing 1968). restricted to the yukon river region in alaska. from this he was able to map the coastal sea currents (giddings 1952). bartholin & hjort (1987) analysed driftwood from isfjorden on the western coast of spits 0 bergen in svalbard (fig. 5 ) . they were able to -500 0 500 1000 1500 2000 2500 date most of the samples with the help of master chronologies from the white sea region. their work showed a potential for further tree-ring studies on arctic driftwood and provided the impetus for this study. 8 ::/,,\ , , , , ~ , , 1 , ~ , , , , i.,,, distance from the fram strait ikm) fig. 4. average drift speeds (cm/second) of ice observed in the transpolar and east greenland currents (from vinje 1982). i i i 10"e 30"e 8 212 0. eggertsson fig. 5. the svalbard area with sampling localities (black dots) and names referred to in the text. v g bj~rrnraya 80"n land 78"n. 76"n. in this paper the dendrochronological method is applied to identify the origin and age of drift wood deposited on the recent shores of wijdefjor den in northern svalbard (fig. 5). the aim is to determine if changes in the relative influx of arc tic and atlantic water masses around svalbard during this century are reflected in the driftwood deposited on the shores. material and methods fieldwork in svalbard was carried out in july 1991. driftwood was collected from three main localities on the eastern shore of wijdefjorden on northern spitsbergen (fig. 5). samples were cut with a chain saw, one sample from each log. some logs still retained the root system, although the bulk of the wood was sawn timber from the forest industry in russia. these logs had broken free during timber floating. no such industry is present in the drainage areas of northward flowing rivers in north america. a total of 310 samples were collected, 276 of which were analysed. their anatomical structures were analysed under a microscope in order to identify the tree species. tree-ring widths were measured on an aniol tree-ring measuring machine connected to a pc computer running the catras software package (aniol 1983). two driftwood as an indicator of relative changes 213 a l“e e ’ 3 i i i i. i i i i i i i i i i i i i 1 1800 1820 1840 1860 1880 1900 1920 1940 1960 1980 year ad b 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1800 1820 1840 1860 1880 1900 1920 1940 1960 1980 year ad fig. 6. driftwood mean curves from svalbard and master chronologies from the white sea region. thick line: mean curves from wijdefjorden; thin line: mean curves from isfjorden; dotted line: chronologies from the white sea region. a. pinus. b . picea. radii were measured and averaged on each drift wood sample, giving a single tree curve for each log. the tree-ring series were correlated with the help of t-values (baillie & pilcher 1973) and “percentages of agreement” values (eckstein & bauch 1969) and also by visual comparison. in cases where the driftwood logs had no bark, the dating reflects the age of the outermost ring observed. those tree ring series showing high correlation values were visually checked by comparing their graphical plots. the best fitted curves were used to build up mean curves. all mean curves pre sented in this paper were quality controlled by the cofecha program (holmes et al. 1986). results driftwood from isfjorden before presenting the results from the present investigation it is important to summarise the results of bartholin & hjort’s (1987) study on the origin of the isfjorden driftwood. in 1984, 145 driftwood logs were sampled for dendrochrono logical analysis from the recent shore on the bohemanflya peninsula in isfjorden (fig. 5). of the 88 pinus samples collected, 62 could be cor related and 41 were used to construct a mean curve for that species (fig. 6). of 57 picea samples analysed, 51 could be correlated and 25 were used to make a mean curve (fig. 6). absolute dates for the driftwood mean curves were obtained by using chronologies from the northwestern part of russia. the best correlations for both the pinus and picea chronologies were obtained with tree ring data from the russian saw and paper mill industry in the white sea region, centred around arkhangelsk (fig. 6; fig. 7). driftwood f r o m wijdefiorden the distribution of different tree species of the driftwood within the wijdefjorden and isfjorden materials is shown in table 1. the main difference is that l a r k is almost absent in the isfjorden material while it is a major component in the wijdefjorden collection. from this it can be con cluded that the origin of the driftwood differs in some way between the two localities. if we examine the distribution of tree species in russia (table 2; fig. 7), l a r k is a minor component in the european part, but it is the major component of the forest areas in eastern siberia. therefore it is logical to conclude that 214 0. eggertsson fig. 7. russia with regions according to table 2. table 1. frequency of the driftwood tree species in isfjorden and wijdefjorden. wijdefjorden wijdefjorden (except white isfjorden (total) sea driftwood) tree species [nl (%i [ni(%) in1 (%i pioco sp. 56 (38.6) 36 (13) 19 (8.5) p*urr sp. 88 (60.7) 167 (60.5) 131 (58.7) lorir sp. l ( 0 . 7 ) 69 (25) 69 (31) broadleaf trees 4 (1.5) 4 (1.8) total 145 276 223 tablr 2. distribution of tree species (in %) in russia, from west to east. the regions are shown in fig. 7 (from kuusela 1990). murmanskaja arkhangel'skaja komi west krasnojarskij irkutskaja jakutskaja magadanskaja treespecies ob. ob. assr siberia k. ob. assr ob. picea abw.r 44 71 58 10 11 6 1 pinursilvcrair 45 23 28 36 14 36 1 1 + lorir sibiriur 1 1 5 41 34 1 lprir dahwica 87 36 pinus canbra + 18 15 13 3 m a sp. 11 4 1ii 24 9 7 othel3 1 3 7 10 1 61 the wijdefjorden material at least partly orig inates from siberia. of the pinus samples from wijdefjorden, 42 could be correlated, and nine were used to con struct a mean tree-ring curve for that species (fig. 8). an attempt to date this mean curve by comparison with the pinus driftwood mean curve from isfjorden and master chronologies from the european part of russia failed. however, a com parison with a pinus master chronology from the middle reaches of the yenisey river in siberia (fig. 3) (eugene vaganov, pers. comm. 1994) driftwood as an indicator of relative changes 215 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1800 1820 1640 1860 1880 1900 1920 1940 1560 1980 year ad fig. 8. pinus driftwood mean curves from northern iceland (thin line), wijdefjorden, northern svalbard (thick line) and a master chronology from the central reaches of the yenisey river in siberia (dotted line). dated it, correlation values, t = 5.89; and per centage of agreement 61.1% (fig. 8). it also correlates with a pinus driftwood mean curve from northern iceland (eggertsson in press). with high correlation values, t = 16.4; and percentage of agreement 77.8% (fig. 8). a considerable part of the pinus samples from northern svalbard therefore derive from central siberia and have the same origin as the icelandic pinus samples. another 36 of the pinus samples remaining could be synchronised and seven of them were used to build a second mean curve for that species. seventeen of the pzcea samples could also be synchronised and seven of them were used t o build mean curve for that species. these two chronologies could be dated with the pinus and the picea driftwood chronologies from isfjorden. fig. 6 shows the plots of the driftwood chrono logies from isfjorden (bartholin & hjort 1987) and the dated driftwood chronologies from wijdefjorden, compared with master chrono logies from the white sea region, one for each species. to summarise, 25% of the pinus samples col lected in the wijdefjorden area originate in the % 25 i i 0 5 1900-1810.19m1930.1d40-18w19801970. i808 1918 1929 1939 1849 1959 1868 1879 drainage area of the yenisey river and 21% arrive from the same place as the pinus samples from isfjorden; i.e. from the white sea region. of the 36 picea samples collected, 17 derived firom the white sea region. the origin of the rest of the samples remains unclear, but it is most likely that the lark samples have an origin in eastern siberia, probably the drainage area of the lena river (fig. 3). the distribution of the dates (the age of the outermost tree ring) of individual logs from wijdefjorden, which originate from the white sea region, is shown in fig. 9. it can be seen that 73% of the dates are concentrated in the time period 1910 to 1950, and only 20% are younger. if this is compared with the results from bartholin & hjort (1987) (fig. lo), where the dates are concentrated around the period from 1950 to 1979, it is evident that driftwood originating from the white sea region is t o a large extent “missing” after 1950 in the wijdefjorden material. the drift wood in isfjorden has only a few dates con centrated in the interval between 1910 and 1950. possibly this is a result of the fact that the isfjor den driftwood was easily accessible to trappers 15 10 5 0 n n = 113 i a n w i ~ i 9 2 0 1 8 9 0 isw iwo i-im 18091819 1829 1938 194919b9 1969 1979 fig. 10. frequency distribution of white sea driftwood samples of different end years (collected around isfjorden in 1984, data from bartholin 6t hjort (1987)). fig. 9. frequency distribution of white sea driftwood samples of different end years (collected around wijdefjorden in 1991). 216 0. eggertsson n = 4 2 0 pinus le00 1910 19m 1930-1940 19so18801070 1808 1819 1928 1939 1949 1959 1909 1070 fig. fl. frequency distribution of siberian (yenisey) driftwood samples of different end years (collected around wijdefjorden in 1991). working in the area, roughly up to the second world war, and that the relatively humid climate on the western coast of spitsbergen is much less favourable for the preservation of driftwood than in the drier conditions to the north and east. the dates of the individual logs from wijdefjorden which originate from siberia (yenisey) are con centrated in the period 1950-1979 (fig. 11). 8cpn 78"n 76"n 74"n 72on 70"n further analysis of the isfiorden driftwood of the 145 samples collected in isfjorden, 78% originate from the white sea region (bartholin & hjort 1987). the rest, 26 pinus and six picea logs, were further analysed by the present author. none of the six picea samples could be dated, but two of the pinus samples were dated with the. pinus driftwood mean curve from the wijdefjor den material that originates from the middle reaches of the yenisey. discussion the influx of arctic water to the barents sea occurs along two main routes, between svalbard and frans josef land, and through the opening between frans josef land and novaja zemlja (dickson et al. 1970) (fig. 12). the isfjorden driftwood of bartholin & hjort (1987) contains only two logs fitting to the siberian pinus mean curve from wijdefjorden, based on 42 logs. the arctic water flowing into the barents sea does not, therefore, seem to feed the west spitsbergen icpe 20'e fig. 12. surface currents in the barents sea (modified from loeog 1989). long arrows = atlantic water; short arrows = arctic water. driftwood as an indicator of relative changes 217 current (fig. 12) with any significant amount of siberian logs, at least not with respect to the coast from isfjorden northwards. thus it is reasonable to assume that the siberian components in the driftwood collection from wijdefjorden have been transported t o that coast with a branch of the transpolar current (fig. 3), flowing from the north. during the period from circa 1910 to 1950, the activity of the warm west spitsbergen current was stronger, transporting white sea driftwood all the way to the wijdefjorden area. but after circa 1950 the input of white sea driftwood decreased and the relative importance of the siberian component increased. these results cor respond well with the climatic records from sval bard, showing a warm regime during the first half of this century which is attributed to increased activity of the warm west spitsbergen current. after circa 1950, the influx of atlantic water decreased, the climate became colder, and the relative occurrences of siberian driftwood trans ported by the transpolar current increased along the northern coast of the archipelago. fig. 13 illustrates the relative changes in the pattern of the ocean currents around svalbard during this century. ‘f$!? t q p ? a 0 fig. 13. relative changes in the strength of the oceanic currents in the svalbard area during this century. a. before circa 1950, b. after circa 1950. final remarks this paper illustrates the potential of applying the dendrochronological method of determining the origin and age of arctic driftwood, and at the same time mapping the relative strength and direction of surface sea currents. this application will, how ever, only be possible on a more regular basis when a dense network of master chronologies is available from throughout the circumpolar boreal forests. such networks are now available for the european part of russia (bartholin & hjort 1987), alaska (cropper & fritts 1981), canada (eggertsson 1994) and partly for siberia. acknowledgements. i thank d. gee for the opportunity of joining his field team to svalbard. the field work was financed by the swedish polar research secretariat and the andree foundation. i thank c. hjort, s. bjdrck and h. linderson for valuable comments on the manuscript. 1 also thank the referees provided by polar research for improving the manuscript. references agardh, j . g. 1869: om den spetsbergska drifvedens ursprung. ofversigt af kongl. vetenskaps-a kademiens forhandlingar 26, 97-119. aniol, r. 1983: tree-ring analysis using catras. den drochronologia i, 45-53. baillie, m. g. l. & pilcher, j. r. 1973: a simple crossdating program for tree-ring research. tree-ring bulletin 3 3 , 7-14. bartholin, t. & hjort, c. 1987: dendrochronological studies of recent driftwood on svalbard. pp. 207-219 in kairiukstis, l., bednarz, z. & feliksik, e. (eds.): methods of den drochronology i . polish academy of sciences, systems research institute, warsaw, poland. cropper, j. p. & fritts, h. c. 1981: tree-ring width chrono logies from the north american arctic. arct. alp. res. 13(3), 245-260. dickson, r. r., midttun, l. & mukhin, a. i. 1970: the hydrographic conditions in the barents sea in august-sep tember 1965-1968. pp. f 2 4 in dragesund, 0. (ed.): inter national 0 g r o u p fish surveys in the barents sea 196s-1968. int. coun. explor. sea cooperative res. rep., ser a (18). eckstein, d. & bauch, j. 1969: beitrag zur rationalisierung eines dendrochronologischen verfahrens und zur analyse seiner aussagesicherheit. forstwiss centralbl. 88. 230-250. eggertsson, 6. 1992: driftwood in the arctic, a dendro chronological study. pp 94-97 in bartholin, t. s.. berg lund, b. e., eckstein, d. & schweingruher, f. h. (eds.): tree rings and environment. lundqua report 34. eggertsson, 6. 1994: mackenzie river driftwood, a den drochronological study. arctic 47(2), 12s136. eggertsson, 6 . in press: origin of the driftwood on the coasts of iceland, a dendrochronological study. jokull43. eurola, s . 1971: the driftwood of the arctic ocean. report from the kevo subarctic research station 7 , 74-80. feyling-hanssen, r. w. 1955: stratigraphy of the marine late pleistocene of billefjorden, vestspitsbergen. norsk polarint. skrifter 107. 186 pp. 218 0. eggertsson giddings, j. l. 1941: dendrochronology in northern alaska. university of alaska publication no iv. 107 pp. giddings, j. l. 1943: the oceans, a plan for mapping arctic sea currents. geogra. rev. 33, 326-327. giddings, j. l. 1952 driftwood and problems of arctic sea currents. proceedings of the american philosophical sociely hhggblom, a. 1982 driftwood in svalbard as an indicator of sea ice conditions. geogrqfiska annaler ( m a ) . 81-94. hjort, c . , adrielsson, l., bondevik, s., landvik, j. l., man gerud, j. & salvigsen. 0. 1992: mytilw edulis on eastern svalbard dating the holocene atlantic water influx maxi mum. pp. 171-175 in mbller, p., hjort, c. & ing6lfsson. 0. (eds): weichselian & holocene glacial and marine history of eart svalbard: preliminary report on the ponamfieldwork in 1991. lundqua report35. holmes, r. l., adams, r. k. & fritts, h. c. 1986: tree-ring chronologies of western north america: california, emtern oregon and northern great barin. chronology series v l . university of arizona, tucson. 40 pp. ingvarson, f. 1903: om drifveden i norra ishafvet. kongl. svemka vetenskaps. akad. handingar 37(1), 1-84. ingvarson, f. 1910 die treibhdlzer auf dem ellesmere-land. 4. 1-57 in report of the second norwegian arctic expedition in ?he “fram” 189l?-lw2, vol. 111. videnskabs-selskabet i kristiania. kelly, p. m., jones, p. d., sear, c. b., cherry, b. s. g. & tavakol, r. k. 1982: variations in surface air temperatures: part 2. arctic regions, 1881-1980. monthly weather review 210(2), 71-83. %(2), 131-142. kindle, e. m. 1921: mackenzie river driftwood. geographical review 11, 50-53. kuusela, k. 1990. the dynamics of boreal coniferous forest3. finnish national found for research and development. hel sinki stra 112. 280 pp. loeng, h. 1989 ecological features of the barents sea. pp. 327-365 in rey, l. & alexander, v. (eds.): proceedings of the sixth conference of the com‘tc arctique intemational, 13 15 may 1965, leiden. lunde, t. 1%3: sea ice in the svalbard region 1957-1962. norsk polarinst. arbok 1963,2434. midttun, l., nakken. 0. & raknes, a. 1981: variations in the geographical distribution of cod in the barents sea in the period 1977-1981. fisken hau. 4 , 1-16. salvigsen, 0.. forman, s. l. & miller, g. h. 1992: ther mophilous molluscs on svalbard during the holocene and their paleoclimatic implications. polar research 11 ( i ) , 1-10. strubing. k. 1968: h e r zusammenhhge zwischen der eis mhrung des ostgrrlnlandstroms und der atmosph&ischen zirkulation iiber dem nordpolarmeer. deutsche hydro graphische zeitschrifi 20 (6), 68-79. vinje, t. e. 1982: the drift pattern of sea ice in the arctic with particular reference to the atlantic approach. pp. 83-% in rey, l. (ed.): the arctic ocean. macmillan press ltd., london and basingstoke. ortenblad, v. t. 1881: om sydgronlands drifved. bihang till kungliga svenska vetenskaps-akaa!em‘ens fiirhandlingar 6(10), 3-34. diversity and distribution of heterotrophic flagellates in seawater of the powell basin, antarctic peninsula research article diversity and distribution of heterotrophic flagellates in seawater of the powell basin, antarctic peninsula zhiyi chen,1,2 jianfeng he,1,2 shunan cao,2 zhibo lu,1 musheng lan,2 hongyuan zheng,1 guangfu luo2 & fang zhang2 1college of environmental science and engineering, tongji university, shanghai, china; 2key laboratory for polar science of natural resources ministry, polar research institute of china, shanghai, china abstract heterotrophic flagellates are essential components of the marine microbial food web. however, how the changes in flagellate populations reflect environmental changes in marine ecosystems is still unclear, especially in polar regions. in this study, we used pyrosequencing to examine the community structure of heterotrophic flagellates (hfs) in the powell basin’s surface waters of the northern antarctic peninsula. otus (operational taxonomic units) of different taxa and the correlations between community structure and environmental factors were analysed. eight taxa of hfs were selected for the principal analysis: telonemia, picozoa, rhizaria, amoebozoa, apusomonas, centrohelida, choanomonada and marine stramenopiles (masts). the hfs were defined as heterotrophic picoflagellates (hpfs; <3 μm) and heterotrophic nanoflagellates (hnfs; >3 μm, <20 μm), which had similar dominant phyla (masts and telonemia). however, their taxonomic composition differed. environmental factors exerted similar effects on the community structure of both hpfs and hnps. compared with the correlation between hpf and environmental factors, the correlation between hnf and environmental factors was stronger. salinity, bacterial biomass and the biological interactions amongst dominant taxa were the main variables to influence the diversity and community structure of hfs. keywords heterotrophic picoflagellates; heterotrophic nanoflagellates; biodiversity; community structure abbreviations ace: abundance-based coverage estimator chl a: chlorophyll a ctab: cetyltrimethylammonium bromide ctd: conductivity–temperature–depth instrument doc: dissolved organic carbon hf: heterotrophic flagellate hpf: heterotrophic picoflagellate hnf: heterotrophic nanoflagellate mast: marine stramenopiles mwm: mixed water mass ncbi: national center for biotechnology information otu: operational taxonomic unit pcr: polymerase chain reaction rda: redundancy analysis wdw: weddell deep water citation: polar research 2021, 40, 5389, http://dx.doi.org/10.33265/polar.v40.5389 copyright: polar research 2021. © 2021 z. chen et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 12 november 2021 competing interests and funding: the authors report no potential conflict of interest. this study was funded by the chinese polar environment comprehensive investigation & assessment programs (chinare-2011–2015), an international cooperation programme of the chinese national arctic and antarctic research expedition (ic201514), and the national natural science foundation of china (grant nos. 41206189, 41476168, 41976230 and 41906201). correspondence to: he jianfeng, key laboratory for polar science, state ocean administration, polar research institute of china, 451 jinqiao road, pudong, shanghai 200136, china. e-mail: hejianfeng@pric.org.cn to access the supplementary material, please visit the article landing page introduction hfs play a crucial role in the microbial food web, being critical consumers of marine plankton, including heterotrophic bacteria, cyanobacteria and eukaryotic algae (arndt et al. 2000; sherr & sherr 2002; domaizon et al. 2003). moreover, their feeding rates directly affect material circulation and nutrient regeneration in the ecosystem (bonkowski 2004; massana et al. 2004), significantly influencing plankton’s community structure. identification and quantification of ecologically significant groups can improve our understanding of marine ecosystems. hfs are widely distributed across the global oceans, including the polar regions, with different characteristic taxonomic compositions in different geographic regions (sohrin et al. 2010). in recent years, with the development of molecular biology techniques, it has been demonstrated that hfs exist in almost all lineages of eukaryotes in the areas studied, and several studies have shown that hf communities are rarely dominated by a single or several species (lovejoy et al. 2007; massana 2011). because most hfs lack easily recognizable morphological features, studies of the primary distributions of hfs are limited (monier et al. 2013). the global warming and sea-ice melting are altering the polar habitat and marine protozoan communities, including hfs. though all levels of the marine microbial food web may respond to climate change (fortier et al. 2006; falk-petersen et al. 2007; laidre et al. 2008), the nanoand pico-levels of plankton, where hfs’ biomass is mainly concentrated (rodriguez-martinez et al. 2013), are especially sensitive to environmental changes (li et al. 2009; zhang et al. 2015). in recent years, the single-celled organisms are gradually tending to form smaller cell structure (li et al. 2009), which suggests that the community structure and biodiversity of hfs may be greatly altered under the circumstances of climate change. the factors affecting the distribution of microorganisms (including hfs) are still controversial because our understanding of the fundamental biogeography and environmental selection forces acting on different hf taxa is limited (hanson et al. 2012; monier et al. 2013). for the global marine plankton, there are still gaps in our knowledge of the dominant populations of hfs in various regions, especially in the polar regions (arndt et al. 2000). fewer studies have characterized the functional diversity of different hfs. some researchers have suggested a non-random dispersion mechanism of the hf’s community structure on the basis of some studies in the environments of anoxic basins and arctic water masses (hamilton et al. 2008; orsi et al. 2011; filker et al. 2013). other studies have hypothesized that dispersal barriers to protist distributions are not necessary (fenchel & finlay 2004; cermeno & falkowski 2009), but that environmental gradients affect some flagellate distribution (thaler & lovejoy 2015). other studies have suggested that community structure differences can be sensitive indicators of external environmental factors (jones & lennon 2010). therefore, to understand and predict changes in marine organism distributions, it is necessary to clarify how environmental variables determine these distributions. in this study, hfs were divided into two size groups: hpfs (× <3 μm) and hnfs (3 μm< × <20 μm). these were analysed to determine the distributions of individual taxa and increase the data available on microbial ecosystems in coastal regions of the antarctic. this study aimed to understand the abundance and diversity of hpfs and hnfs in the powell basin and nearby areas around the northern antarctic peninsula and investigate the influence of environmental factors, such as temperature, salinity, chl a concentration and nutrients, on hf community structure and abundances. materials and methods sample collection samples were collected between 30 december 2011 and 29 january 2012, during the 28th chinese national antarctic research expedition. four sampling sections and 13 sampling stations were established around the northern antarctic peninsula, including in the powell basin and its surrounding area (60.10°s–63.15°s, 44.68°w–54.68°w), from elephant island to the southern orkney tableland area, including the northern area of bransfield strait (fig. 1). the samples were taken from the layer of maximum oxygen, a depth of 25 m. fig. 1 location of sampling stations in the powell basin, northern antarctic peninsula. the water samples were collected using a sbe911plus ctd instrument (sea-bird electronics) equipped with 24 niskin bottles. physical parameters (temperature and salinity) were measured at the same time as sampling. about 2 l of seawater was prefiltered through a 20-μm mesh sieve to remove most mesozooplankton and large particles. each sample was then filtered through a 3-μm pore size polycarbonate membrane (all membranes were from whatman), to retain the nano-sized hfs. the filtrate was finally filtered through a polycarbonate membrane (diameter 47 mm and pore size 0.2 μm) with vacuum pumping to retain the pico-sized hfs. the membrane samples were immediately frozen at −80°c and shipped to the laboratory for microbial diversity analysis. each water sample was filtered through a 0.45-μm cellulose acetate membrane filter (whatman) for nutrient analysis. nitrite (no2), nitrate (no3), phosphate (po4) and silicate (sio3) were measured with a san++ nutrient autoanalyser (skalar), using methods explained by müller (2007) and he et al. (2012). ammonia (nh4) was analysed using a spectrophotometer. to determine the chl a concentration, about 2 l of seawater in each sample was filtered through a 47-mm diameter whatman gf/f filter. the filter was fully leached with 90% acetone and stored at −20°c for 24 hr. analysis was conducted onboard in the research vessel using a 10 au field fluorometer (turner designs), by the methods of he et al. (2012). the amount of eukaryotic plankton and bacteria were detected by a bd facscaliburtm flow cytometer. dna sequencing and 18s rrna sequence analyses to analyse the biodiversity and community composition, the dna extraction, pcr amplification of rrna genes and the pyrosequencing and bioinformatics analyses were completed in the key laboratory for polar science of natural resources ministry in shanghai. the dna extraction was conducted by the ctab method. the ctab solution was treated using lysozyme (final concentration, 5 mg ml-1) and proteinase k (final concentration, 10 mg ml-1). samples were put in the ctab solution with a final concentration of 2% (1.4 m nacl, 100 mm tris-hcl, 4% pvp, 70 mm β-mercaptoethanol, ph 8.0) to extract the dna. rnase was added (final concentration, 20 μg ml) to remove the rna contamination. the final concentration and purity were checked by 0.7% agarose gels. moreover, the pcr amplification was completed by the v4 region of the 18s rrna. the amplification was under the condition of the universal primer pair 3ndf (5’-ggcaagtctggtgccag-3’) and the reverse primers v4_euk_r2 (5’-acggtatctratcrtcttcg-3’) (brate et al. 2010). the pcrs were carried out in 20 μl reaction volumes with a 20-ng dna template, 250 μm dntps, 0.25 μm of each primer, 1x pcr buffer and 2.5 u pfu polymerase (fermentas). the pcr condition involved initial denaturation at 95°c for 2 min, followed by 25 cycles of denaturation at 94°c for 30 s, annealing at 55°c for 30 s and extension at 72°c for 30 s, with a final extension of 72°c for 10 min. pcr products (3 μl) were checked on a 2% agarose gel, purified using a dna gel extraction kit (axygen, china). all the final products from the samples were mixed in the equal ratios for the pyrosequencing with genome sequencer flx titanium (454/roche life sciences). more detail process, conditions and laboratory analysis were obtained in the previous study (zhang et al. 2019). a bioinformatics analysis was conducted. mothur software, version 1.32.0 (schloss et al. 2009), was used to extract the nonrepetitive sequences and identify and remove duplicate sequences. the sequences with high qualities (≥200 bp length, quality score ≥25, matched to barcode and primer and containing no ambiguous characters) were aligned with the reference sequences in the silva rna database (silva seed v115; pruesse et al. 2007) and were clustered to otus at 97% similarity with a cut-off of 80 compared with the reference sequences. the community diversity and similarity amongst all water samples were also analysed with otus of 97% similarity in perl and mothur (schloss et al. 2009). the attributions of each sequence at different levels (from phylum to genus) were added according to the ncbi database. the sequence data were submitted to the ncbi sequence read archives under bioproject number prjna642996. diversity and community structure analyses a sampling map was generated using the ocean data view (schlitzer et al. 2018) software and modified with adobe photoshop cc 2015. the r software (version 3.4.4; mckenna et al. 2016) was used to determine the α-diversity indices (ace, chao, shannon’s diversity, simpson’s index and good’s coverage) based on the normalized sequence data. spearman’s correlation analyses were performed at the otu level with the complot package in r (version 3.4.4) to investigate the significance of the correlations between various environmental factors (temperature, salinity, nutrients, chl a, eukaryotic plankton and bacteria) and the hf communities. an rda was performed using the canoco 5 programme to assess the correlations between the variations in the communities at the 13 antarctic locations (based on the relative abundances of all otus) and environmental variables (temperature, salinity, nutrients, chl a, eukaryotic plankton and bacteria). results basic environmental parameters and α-diversity indices the seawater properties at the 13 sampling stations were measured to a depth of 25 m (supplementary table s1). during the sampling period, water temperature ranged from −1.30 to 1.16°c, and the salinity was 33.58–34.50 psu. the chl a levels varied from 0.08 μg/l at station d3-8 to 2.11 μg/l at station d5-3. the density of phototrophic picoeukaryotes varied from 1.78 × 106 cells/l at station d3-3 to 7.99 × 106 cells/l at station d3-5. the density of heterotrophic bacteria was 1.64 × 108 to 6.09 × 108 cells/l. the highest bacterial biomass occurred at station d4-7, with another two peaks at d3-5 and d5-3. seawater [po4] was 1.55–2.34 μm, [no2] was 0.10–0.34 μm, [no3] was 25.04–47.53 μm, [nh4] was 25.04–47.53 μm and [sio3] was 66.25–87.10 μm. in this study, 159–664 otus were detected in the hpf group and 97–450 in the hnf group (table 1). good’s coverage was 84–94% in the hpf group and 82–93% in the hnf group, indicating that the vast majority of otus were sequenced. specimens from samples d3-3 in the hpf group and d5-8 in the hnf group showed the highest ace (4062 and 4108, respectively) and chao indices (6387 and 7058, respectively), indicating that the highest community richness occurred at these sites. the highest shannon index in the hpf group occurred in samples d4-7 (6.02), followed by samples d5-1 (5.56) and d2-5 (5.16). in the hnf group, the highest value occurred in samples d3-3 (5.70), followed by samples d4-7 (5.46) and d5-1 (5.20). the highest simpson’s index of the hpf group was detected in sample d3-1 (0.60), followed by samples d2-3 (0.578) and d2-5 (0.577); in the hnf group, the highest value occurred in sample d2-5 (0.72), followed by samples d2-3 (0.65) and d3-1 (0.60). therefore, these samples had the most significant community diversity.   table 1 comparison of the richness and diversity indices for estimated otus (clustered at 97% identity) based on 18s rrna gene libraries, determined with a pyrosequencing analysis of antarctic waters. sample id hpf hnf coverage otu reads chao ace shannon simpson coverage otu reads chao ace shannon simpson d2-3 0.8952 323 1817 3014 5321 4.63 0.5779 0.9004 153 619 3446 6055 4.27 0.6543 d2-5 0.8903 297 1580 3164 5176 5.16 0.5767 0.8968 121 377 3336 5728 4.29 0.7175 d2-8 0.9179 150 645 2551 3968 4.34 0.5149 0.8834 159 724 3656 6730 4.64 0.4975 d3-1 0.8764 400 2016 3019 5117 5.04 0.6035 0.9102 195 709 2532 4067 3.91 0.6002 d3-3 0.8820 307 1285 4062 6387 5.09 0.5296 0.8396 109 256 4094 6489 5.70 0.7206 d3-5 0.9143 436 2955 2917 4607 4.35 0.2612 0.9023 442 3781 3276 4744 4.56 0.4725 d3-8 0.8986 316 2253 3380 5590 4.96 0.4878 0.8828 229 1591 3304 5625 5.17 0.3138 d4-7 0.8439 425 1817 4042 6012 6.02 0.3630 0.8200 450 215 3302 5251 5.46 0.4200 d4-11 0.9126 459 2789 3150 5021 3.96 0.1065 0.8758 97 3248 3874 6429 4.94 0.2322 d5-1 0.8739 347 1312 3797 5977 5.56 0.3976 0.8693 170 561 3543 6070 5.20 0.4998 d5-3 0.8961 371 2278 3909 6043 5.07 0.4221 0.8902 145 891 3278 5480 5.00 0.3127 d5-6 0.9036 664 5301 3497 5404 4.97 0.5135 0.9281 305 1398 2523 4431 3.48 0.4641 d5-8 0.9399 494 8474 2666 4380 4.07 0.5596 0.8835 379 1677 4108 7058 4.89 0.4925 hf community composition the libraries’ coverage at a cluster distance of 0.03 was high for all 13 samples, and the rarefaction curves reached saturation. the sequence data showed the abundance of each phyla or genera, and the otu data showed the diversity of hfs community. hpf and hnf richness differed significantly across all the samples. hpf reads’ mean richness was 2625 (range 645–8474 reads), with a peak at site d5-8. the mean richness of hnf reads was 1234 (range 215–3781 reads), with a peak at d3-5 (table 1). the hnf communities exhibited similar abundances and levels of diversity to the hpf communities. eight major hpf taxa were identified in the communities in the powell basin, and seven major hnf taxa were detected in the samples. the reads of each taxa identified were present at relatively high abundance. in this study, masts, telonemia and rhizaria were frequently detected at high biodiversity. the dominant taxon in all samples was masts, which accounted, on average, for 63.86% of the total otus in the hpf group and 52.93% of the total otus in the hnf group (fig. 2f). telonemia was the second most represented taxon, accounting for 15.96% of the total otus in the hpf group and for 26.72% of the total otus in the hnf group, on average. masts (including mast-1a, mast-1b, mast-1c, mast-2, mast-3, mast-7, mast-8, mast-9 and mast-12), amoebozoa, apusomonas, centrohelida, choanoflagellates, rhizaria and telonemia were observed in both the hpf and hnf groups, whereas picozoa (4.12% of the total otus and 16.03% of sequences, on average) was only found in the hpf group, accounting for the third largest proportion. rhizaria was the third most represented group in the hnf group, whereas in the hpf group, there were fewer sequences of rhizaria than picozoa. rhizaria was also the third most represented hf taxon at the out level, accounting for slightly more hfs than picozoa. in addition to the most dominant taxa, amoebozoa, apusomonas and centrohelida were detected at relatively low abundances. some of these were only detected in a subset of samples in this region (fig. 2). fig. 2 average relative percentages of otus for each heterotrophic flagellate group within different communities. “others” includes amoebozoa, apusomonas and centrohelida. (a) the average percentage of all taxa’s relative otu in hpf group; (b) the average percentage of all taxa’s relative otu in hnf group; (c) the average percentage of mast’s relative otu in hpf group; (d) the average percentage of mast’s relative otu in hnp group; (e) average relative percentages of otu at pico-level; (f) average relative percentages of otu at the nano-level. the community structure in most of the stations was similar, as showed by the proportions of otus at each station (fig. 2a, b). the total number of otus in the hnf group was lower than that in the hpf group, and hnf’s diversity was higher at d3-5 and d4-11 than at the other stations in the same section. in the hpf group, station d2-8 exhibited relatively lower reads and diversity than the other stations. in contrast, the group’s diversity and sequences were higher at d5-6 and d5-8 than at the other stations. masts accounted for the most substantial proportion of otus, and telonemia constituted the second largest proportion of otus at all the stations, except d5-3 and d5-8 (fig. 2a). at d5-8, picozoa accounted for the highest proportion of otus, followed by amoebozoa, with a very similar proportion. however, picozoa was rarely found at the other stations, with the sequence presence being lower than 1.62% (fig. 3). the most significant difference between the hnf and hpf groups was that picozoa was not detected amongst the hnfs. masts accounted for the highest proportion of otus at all stations, except d5-3 (fig. 2a, b), where rhizaria constituted the highest proportion of otus, followed by masts. at d2-5, choanoflagellates accounted for the second-largest proportion of otus, and rhizaria provided the second largest proportion of otus at d3-3. in contrast, telonemia formed the second largest proportion of otus at the other stations. the community structure at d5-3 was significantly different from those at the other stations. in the hpf group, amoebozoa and centrohelida were not found at every station, and the distribution of apusomonas was also patchy in the hnf group. the other four taxa were detected in all samples. fig. 3 heterotrophic flagellate community structure at different stations, based on the reads data sets. stacked column graphs illustrate the abundances of the dominant taxa of heterotrophic flagellates in this study. the middle two columns in each set represent the community structure of hnf and hpf; p presents hpf and n represents hnf. the columns on two sides are the distribution of each clade of mast. in this research, mast-1 did not account for the most significant proportion of otus in the hpf group, and mast-3 and mast-7 accounted for the most generous proportions at most stations (fig. 2c, d). however, in the hnf group, mast-1 made up the largest proportion at most stations. the proportion of mast-3 was higher than in the hpf group at some stations, and the proportion of mast-7 was significantly lower than for the hpf group. the number of nano-masts was significantly lower than the number of pico-masts, with peaks at d3-5, d3-8 and d4-11, as for the pico-mast group. d5-8 was a unique station insofar as nano-masts outnumbered pico-masts. mast-9 was not detected in the hnf group. in both the hnf and hpf groups, within the mast-1 clade, mast-1c accounted for the highest proportions of otus and reads at each station (fig. 3). mast-1a accounted for a proportion similar to that of mast-1b in the hpf group, but in the hnf group, mast-1a accounted for a higher proportion than in the hpf group; mast-1b was rarely detected. correlations between environmental factors and hnf or hpf communities rda ordination was carried out to analyse the relationships between the hf communities and the environmental variables at these antarctic locations. in the rda ordination of hpf (fig. 4), the eigenvalues for axes i and ii were 0.444 and 0.643, respectively, and the taxa–environment correlations for the first two axes were 0.99 and 0.99, respectively. salinity and chl a accounted for the most significant amount of variability in the hpf community, followed by temperature, but [nh4] was also a highly significant explanatory variable along the second axis. the rda results for hnf demonstrated that the hnf community compositions differed somewhat from those of the hpf group. the eigenvalues for axes i and ii were 0.362 and 0.590, respectively, and the taxa–environment correlations for the first two axes were 0.99 and 0.97, respectively. salinity accounted for the most significant variability in the hnf community, followed by [po4] and [nh4], but bacteria density was also a highly significant explanatory variable along the second axis. fig. 4 redundancy analysis of the environmental factors affecting hpf and hnf communities, based on the otu data sets. red arrows represent environmental factors, blue arrows represent nutritional factors and each dot represents a sample. the labels on the graph show the percentage differences between the hpf group and the hnf group. in the hnf group, most of the dominant taxa exhibited significant correlation with environmental factors, except apusomonas, centrohelida, mast-1b and mast-12. different environmental factors had different effects, as indicated by the correlation coefficients for hnf (fig. 5). for example, salinity had a significant effect on most clades of masts (including mast-1a, mast-1c, mast-2, mast-3 and mast-8), choanoflagellates and rhizaria; ammonia harmed amoebozoa and rhizaria but a positive effect on mast-7 and mast-8. mast-2 and mast-3 showed opposite correlations with temperature. in summary, there were only three taxa in hpf groups that displayed a significant correlation with only one of the measured factors, and most taxa showed significant correlations with more than two environmental factors. in the hpf group, only a small proportion of the dominant taxa showed a significant correlation with environmental factors. for instance, although masts were the dominant taxon, only the mast-2 clade showed significant correlations with environmental factors. mast-2 correlated negatively with temperature, salinity and chl a and positively with bacteria density. fig. 5 pairwise comparisons of environmental factors and heterotrophic flagellate taxa; the colour, size and gradient of symbols denote spearman’s correlation coefficients. conversely, the mast-12 clade correlated negatively with bacteria density. choanoflagellates, telonemia and mast-2 correlated negatively with temperature. amongst them, telonemia showed a lower negative correlation. in conclusion, only two taxa showed a significant correlation with only a single parameter measured in this study, whereas three taxa were correlated significantly with more than one environmental factor. the remaining taxa showed no correlation with any environmental factor. spearman’s correlation analyses showed that the correlations amongst the dominant taxa of hfs were also significant, indicating that biological interactions are also an essential factor influencing hf diversity and community structure in the sea around the northern tip of the antarctic peninsula. from the correlation matrix (fig. 5), nine of the 16 dominant taxa in the hpf group were correlated significantly with the presence of at least two other taxa, and eight of the 14 dominant taxa in the hnf group were correlated significantly with the presence of at least two other genera. of the correlations between taxa amongst the hnf group populations, rhizaria, choanoflagellates, centrohelida, mast-1a, mast-1c, mast-2 and mast-3 were correlated significantly with more than two other phyla or genera. most of these phyla or genera were correlated strongly with each other, either positively or negatively. amoebozoa, apusomonas, mast-1b, mast-7 and mast-8 only showed significant correlations with one other taxon. there were no significant correlations between telonemia or mast-12 and any other taxon. discussion taxonomic compositions with hpfs and hpfs distribution according to the results above, the community structure in most of the stations was similar, and the abundance and diversity of hnf group were lower than the hpf group. amongst the two groups with different size, mast and telonemia were dominant at most stations. however, the community structure at some stations was significantly different from that at other stations. luo et al. (2016), who investigated the diversity of microbial eukaryotes in the coastal region of the fildes peninsula, antarctic, also showed that masts and telonemia occupied significant positions in the hf group, whereas picozoa accounted for less than 2.43% of reads per sampling site. in this research, picozoa, amoebozoa and centrohelida were present in only some samples; the remaining five taxa were detected in all samples. picozoa was thought to prefer colloidal material or small viruses more than specific bacteria and phytoplankton prey, which may limit the scope of survival (seenivasan et al. 2013; thaler & lovejoy 2015). there were more sequences reads from d5-6 and d5-8 than from the other stations, indicating that the abundance of hfs near the weddell sea was much higher than the other areas in the powell basin. the community structure at d5-8 was significantly different from those at the other stations. at d5-8, the number of reads for and the relative percentage of rhizaria was higher than at all other stations. amoebozoa and picozoa were mainly found at d5-8 and were very rare at the other stations. however, the environmental factors at d5-3 and d5-8 did not differ significantly from those at the other stations, so the differences between their community structure were possibly related to water mass interactions, biological interactions or other factors. the numbers of otus and reads were much lower in the hnf group than in the hpf group, which may be evidence of microbial miniaturization in the polar regions (hanson et al. 2012). in the d2 section, the proportion of telonemia was higher than that of masts, implying that the abundance of nano-sized telonemia in this section was higher than that of nano-masts. because the number of reads in the samples from the stations in this section was relatively small, it cannot be inferred that telonemia had a survival advantage over masts in this area. distribution of masts as the dominant group in the hf community, masts exhibit high taxonomic diversity, and members of this taxon play many ecological roles in the marine ecosystem (massana et al. 2006). the mast-1, mast-2, mast-3 and mast-7 clades are common in the arctic ocean (lovejoy et al. 2006). mast-1, which includes three groups, was particularly abundant in the antarctic peninsula samples (massana et al. 2006). mast-3 is the most abundant mast clade worldwide (logares et al. 2012). mast-7 is also widespread globally and is predominantly reported in arctic waters (massana et al. 2006). luo et al. (2016) reported that off the coast of king george island in the antarctic, mast-1a was the most abundant member of mast-1, and mast-1c was the second major group. in contrast, mast-1b was rarely detected in any sample. these findings are consistent with our results, suggesting a widespread, relatively stable distribution of mast-1 off the antarctic peninsula coast. however, in luo’s research, mast-8 was more abundant than mast-7, and mast-3 was rarely detected, which is inconsistent with our results. these data suggest that regional differences significantly affect mast clades other than mast-1. in recent studies, several differences in the spatial scale distribution of the mast clades have been reported, which may be attributable to different food sources and predation pressures (piwosz & pernthaler 2010; lin et al. 2012). comeau et al. (2013) noted that masts tend to coexist with diatoms. in some grazing experiments and stable isotope probing experiments, mast-1 and mast-7 consumed heterotrophic bacteria and cyanobacteria (frias-lopez et al. 2009; massana et al. 2009). cyanobacteria are less prevalent in the arctic and antarctic than in other parts of the world (waleron et al. 2007; grebert et al. 2018), so it has been suggested that mast-1 and mast-7 may feed on the abundant, similarly sized photosynthetic eukaryote micromonas in polar areas (lovejoy et al. 2007). in the present study, mast-7 in the hnf group correlated significantly with the abundance of photosynthetic eukaryotes and heterotrophic bacteria, explaining the different distribution of masts from that in the nearby sea. effects of environmental and biological interactions there were no significant differences amongst the environmental factors in this study, such as temperature, nutrient salt, sampling depth and chl a concentration, at the various sites. of these environmental factors, salinity and bacteria’s biomass more significantly affected hf diversity and community structure than the other environmental factors. according to previous studies, the bacterial community structure also influences the diversity and community structure of hfs. grazing experiments have shown that many dominant genera of hfs have different predation tendencies. for instance, picozoa is thought to consume colloidal material and, perhaps, small viruses and may be less constrained by prey availability (seenivasan et al. 2013). telonemia is thought to feed on cryptophytes and other nanophytoplankton (brate et al. 2010), so members of that phylum may be more abundant in oligotrophic systems dominated by phytoflagellates (ardyna et al. 2011). the majority of taxa in the rhizaria are described as predators of bacteria and small phytoplankton and have been observed in association with diatoms (thaler & lovejoy 2012). according to the research of cao et al. (2019) and chen et al. (2021), the bacteria community structure in station d5-8 was different from other stations. in d5-8, the dominant taxon and the proportion of the total bacterial population attributable to the dominant genus also differed from other stations. the bacterial diversity was significantly higher than at the other stations (cao et al. 2019). therefore, the bacterial community structure may be an important factor affecting the hf community structure at d5-8. according to the spearman’s correlation analyses, the result indicates that both cooperation and competition are operating amongst these taxa and the possibility of mutual predation. the specific predation relationship needs to be further studied through predation experiments. geographic distributiozn hfs occur throughout the world, and the dominant groups vary in different habitats. the flagellate clades of rhizaria that belong to cryomonadida, like cryothecomonas and protaspis (mylnikova & mylnikov 2012), have been reported in sea ice and the water column (garrison et al. 2005), dominating in sea ice (comeau et al. 2013) and found at lower abundances in the water column (thaler & lovejoy 2015). in the present research, the samples were collected from seawater, and rhizaria had fewer sequences than mast and telonemia in both hnf and hpf groups. some other flagellate clades that belong to cryomonadida, like rhogostoma, rhizapis and capsellina (mylnikova & mylnikov 2012), have been reported only in freshwater. telonemia has been detected with 18s rrna analyses from freshwater and seawater, including marine-specific clades (brate et al. 2010). the marine-specific clades of telonemia may influence the proportion of telonemia in the hf community structure. choanoflagellates occur in freshwater, marine water, sea ice (ikavalko & gradinger 1997) and even sediments (dayel et al. 2011). choanoflagellates were reported to be more dominant and phylogenetically more diverse than most clades of hfs in the canada basin and had a few phylotypes that were restricted to a given region, like sea ice (thaler & lovejoy 2015). compared with mast, telonemia and rhizaria, choanoflagellates occupy a lower proportion in the community but have a higher proportion at some stations. as for other reported mast clades, mast-2 is reported as the most abundant mast in sea ice (piwosz et al. 2013), but in the present research, mast-2 was not dominant in seawater. mast-4 was not detected in this area; it has been reported widespread in global oceans but appears to be absent from cold waters, including the arctic (rodriguez-martinez et al. 2013). in the coastal area of the antarctic peninsula’s northern tip, fluctuations in the seabed topography interact with ocean currents, producing a very complex water exchange process (hernandez-molina et al. 2006) that may affect the biodiversity of the coastal antarctic ecosystem. the area investigated in the present study has a unique geographic location in terms of the southern ocean currents (jiuxin et al. 2016). as the area is the nexus between the antarctic circumpolar current and the weddell sea circulation, seawater is exchanged there, which may cause planktonic communities to mix. existing data and related studies of water-mass interactions show that the surface water in the powell basin, off the northern antarctic peninsula, was homogeneous during the sampling period of the present study (jiuxin et al. 2016; cao et al. 2019; chen et al. 2021). the wdw and the higher-temperature water masses observed in the d2 section are unlikely to be locally formed and transported along the continental slope. this may be one reason why the proportion of telonemia was higher than that of masts in the d2 section. the highest temperature in the d5 section occurred to the south of d5-8, which is the core of the wdw. the area around d5-8 may be the part of the wdw in the weddell sea that flows out from the south orkney platform (jiuxin et al. 2016). this outflow may contribute to the abnormal community structure at d5-8. the sequence reads at d5-6 and d5-8 were much higher than at the other stations, indicating that the abundance of hfs was much higher near the weddell sea than at the other stations in the powell basin. recent studies have shown that many marine microbiota in the antarctic have circumpolar distributions, indicating that the antarctic circumpolar current and the antarctic coastal current have a wide range of influence in this region. therefore, the hf community structure in this region may be similar to other regions around the south pole, which needs further study. conclusion in summary, the results of this study suggest that salinity, bacterial biomass and the biological interactions between dominant taxa contribute more to hf diversity and community structure than other environmental factors. hfs of different sizes display different levels of diversity and different community structure. however, within the same particle-size class, each station’s dominant taxa were similar. the shared otus in these samples confirmed the similarity of the distributions of the most significant taxa. the hf community structure at d5-8 differed significantly from that at the other stations, and the bacterial community structure at d5-8 was also different from other stations at the same time. to some extent, this result also indicates that the bacteria community plays a significant role in influencing the diversity and community structure of hfs in the same habitat, and more data and research are needed on the influence of other food sources on flagellate. in this study, we report the occurrence and abundance of hnfs and hpfs, which are considered to play essential roles in the antarctic ecosystem. at present, little information is available on the distributions and structure of coastal microbial communities around the antarctic peninsula, especially heterotrophic protozoa. the monitoring data on hf community structure reported in this study exemplify samples that were collected in summer in this region and may be compared with future data to investigate the sensitivity of hfs to potential climate change. acknowledgements the authors are grateful to professor shi jiuxin of the ocean university of china for kindly providing temperature and salinity data and to professor pan jianming of the second institute of oceanography for providing nutrient data. the cruise was supported by the rv xuelong ice-breaker. data availability statement the data sets generated for this study can be found in the national center for biotechnology information sequence read archive under bioproject number prjna642996, accessible online at https://dataview.ncbi.nlm.nih.gov/object/prjna642996?reviewer=tg7jmm2k1o9qge4qv7f8bqurdd. references ardyna m., gosselin m., michel c., poulin m. & tremblay j.e. 2011. environmental forcing of phytoplankton community structure and function in the canadian high arctic: contrasting oligotrophic and eutrophic regions. marine ecology progress series 442, 37–57, doi: 10.3354/meps09378. arndt h., dietrich d., auer b., cleven e.-j., grafenhan t., weitere m. & mylnikov a.p. 2000. functional diversity of heterotrophic flagellates in aquatic ecosystems. in b.s.c. leadbeater & j.c. green (eds.): the flagellates: unity, diversity and evolution. pp. 240–268. london: taylor & francis. bonkowski m. 2004. protozoa and plant growth: the microbial loop in soil revisited. new phytologist 162, 617–631, doi: 10.1111/j.1469-8137.2004.01066.x. bråte j., klaveness d., rygh t., jakobsen k.s. & shalchian-tabrizi k. 2010. telonemia-specific environmental 18s rdna pcr reveals unknown diversity and multiple marine–freshwater colonizations. bmc microbiology 10, article no. 168, doi: 10.1186/1471-2180-10-168. cao s.n., he j.f., zhang f., lin l., gao y. & zhou q.m. 2019. diversity and community structure of bacterioplankton in surface waters off the northern tip of the antarctic peninsula. polar research 38, article no. 3491, doi: 10.33265/polar.v38.3491. cermeno p. & falkowski p.g. 2009. controls on diatom biogeography in the ocean. science 325, 1539–1541, doi: 10.1126/science.1174159. chen z.y., lu z.b., gao y., hao q. & he j.f. 2021. determination of bacterioplankton abundance, production and carbon budget in the northwest weddell sea. geomicrobiology journal 38, 607–619, doi: 10.1080/​01490451.2021.1914783. comeau a.m., philippe b., thaler m., gosselin m., poulin m. & lovejoy c. 2013. protists in arctic drift and land-fast sea ice. journal of phycology 49, 229–240, doi: 10.1111/jpy.12026. dayel m.j., alegado r.a., fairclough s.r., levin t.c., nichols s.a., mcdonald k. & king n. 2011. cell differentiation and morphogenesis in the colony-forming choanoflagellate salpingoeca rosetta. developmental biology 357, 73–82, doi: 10.1016/j.ydbio.2011.06.003. domaizon i., viboud s. & fontvieille d. 2003. taxon-specific and seasonal variations in flagellates grazing on heterotrophic bacteria in the oligotrophic lake annecy—importance of mixotrophy. fems microbiology ecology 46, 317–329, doi: 10.1016/s0168-6496(03)00248-4. falk-petersen s., pavlov v., timofeev s. & sargent j.r. 2007. climate variability and possible effects on arctic food chains: the role of calanus. in j.b. ørbæk et al. (eds.): arctic alpine ecosystems and people in a changing environment. pp. 147–166. berlin: springer. fenchel t. & finlay b.j. 2004. the ubiquity of small species: patterns of local and global diversity. bioscience 54, 777–784, doi: 10.1641/0006-3568(2004)054[0777:tuossp]2.0.co;2. filker s., stock a., breiner h.w., edgcomb v., orsi w., yakimov m.m. & stoeck t. 2013. environmental selection of protistan plankton communities in hypersaline anoxic deep-sea basins, eastern mediterranean sea. microbiologyopen 2, 54–63, doi: 10.1002/mbo3.56. fortier l., sirois p., michaud j. & barber d. 2006. survival of arctic cod larvae (boreogadus saida) in relation to sea ice and temperature in the northeast water polynya (greenland sea). canadian journal of fisheries and aquatic sciences 63, 1608–1616, doi: 10.1139/f06-064. frias-lopez j., thompson a., waldbauer j. & chisholm s.w. 2009. use of stable isotope-labelled cells to identify active grazers of picocyanobacteria in ocean surface waters. environmental microbiology 11, 512–525, doi: 10.1111/j.1462-2920.2008.01793.x. garrison d.l., gibson a., coale s.l., gowing m.m., okolodkov y.b., fritsen c.h. & jeffries m.o. 2005. sea-ice microbial communities in the ross sea: autumn and summer biota. marine ecology progress series 300, 39–52, doi: 10.3354/meps300039. grebert t., dore h., partensky f., farrant g.k., boss e.s., picheral m., guidi l., pesant s., scanlan d.j., wincker p., acinas s.g., kehoe d.m. & garczarek l. 2018. light color acclimation is a key process in the global ocean distribution of synechococcus cyanobacteria. proceedings of the national academy of sciences of the united states of america 115, e2010–e2019, doi: 10.1073/pnas.1717069115. hamilton a.k., lovejoy c., galand p.e. & ingram r.g. 2008. water masses and biogeography of picoeukaryote assemblages in a cold hydrographically complex system. limnology and oceanography 53, 922–935, doi: 10.4319/lo.2008.53.3.0922. hanson c.a., fuhrman j.a., horner-devine m.c. & martiny j.b. 2012. beyond biogeographic patterns: processes shaping the microbial landscape. nature reviews microbiology 10, 497–506, doi: 10.1038/nrmicro2795. he j.f., zhang f., lin l., cai m.h., yang h.z. & wang x.g. 2012. effects of the 2010 chile and 2011 japan tsunamis on the antarctic coastal waters as detected via online mooring system. antarctic science 24, 665–671, doi: 10.1017/s0954102012000326. hernandez-molina f.j., larter r.d., rebesco m. & maldonado a. 2006. miocene reversal of bottom water flow along the pacific margin of the antarctic peninsula: stratigraphic evidence from a contourite sedimentary tail. marine geology 228, 93–116, doi: 10.1016/j.margeo.2005.12.010. ikavalko j. & gradinger r. 1997. flagellates and heliozoans in the greenland sea ice studied alive using light microscopy. polar biology 17, 473–481, doi: 10.1007/s003000050145. jiuxin s., yongming s., yutian j., guanghua h. & miao w. 2016. water masses and exchanges in the region around the northern tip of the antarctic peninsula observed in summer 2011/2012. chinese journal of polar research 28, 67–79. jones s.e. & lennon j.t. 2010. dormancy contributes to the maintenance of microbial diversity. proceedings of the national academy of sciences of the united states of america 107, 5881–5886, doi: 10.1073/pnas.0912765107. laidre k.l., stirling i., lowry l.f., wiig o., heide-jorgensen m.p. & ferguson s.h. 2008. quantifying the sensitivity of arctic marine mammals to climate-induced habitat change. ecological applications 18, s97–s125, doi: 10.1890/06-0546.1. li w.k.w., mclaughlin f.a., lovejoy c. & carmack e.c. 2009. smallest algae thrive as the arctic ocean freshens. science 326, 539–539, doi: 10.1126/science.1179798. lin y.c., campbell t., chung c.c., gong g.c., chiang k.p. & worden a.z. 2012. distribution patterns and phylogeny of marine stramenopiles in the north pacific ocean. applied and environmental microbiology 78, 3387–3399, doi: 10.1128/aem.06952-11. logares r., audic s., santini s., pernice m.c., de vargas c. & massana r. 2012. diversity patterns and activity of uncultured marine heterotrophic flagellates unveiled with pyrosequencing. isme journal 6, 1823–1833, doi:10.1038/ismej.2012.36. lovejoy c., massana r. & pedros-alio c. 2006. diversity and distribution of marine microbial eukaryotes in the arctic ocean and adjacent seas. applied environmental microbiology 72, 3085–3095, doi: 10.1128/aem.72.5.3085-3095.2006. lovejoy c., vincent w.f., bonilla s., roy s., martineau m.j., terrado r., potvin m., massana r. & pedros-alio c. 2007. distribution, phylogeny, and growth of cold-adapted picoprasinophytes in arctic seas. journal of phycology 43, 78–89, doi: 10.1111/j.1529-8817.2006.00310.x. luo w., li h.r., gao s.q., yu y., lin l. & zeng y.x. 2016. molecular diversity of microbial eukaryotes in sea water from fildes peninsula, king george island, antarctica. polar biology 39, 605–616, doi: 10.1007/s00300-015-1815-8. massana r. 2011. eukaryotic picoplankton in surface oceans. annual review of microbiology 65, 91–110, doi: 10.1146/annurev-micro-090110-102903. massana r., castresana j., balague v., guillou l., romari k., groisillier a., valentin k. & pedros-alio c. 2004. phylogenetic and ecological analysis of novel marine stramenopiles. applied environmental microbiology 70, 3528–3534, doi: 10.1128/aem.70.6.3528-3534.2004. massana r., terrado r., forn i., lovejoy c. & pedros-alio c. 2006. distribution and abundance of uncultured heterotrophic flagellates in the world oceans. environmental microbiology 8, 1515–1522, doi: 10.1111/j.​1462-2920.2006.01042.x. massana r., unrein f., rodriguez-martinez r., forn i., lefort t., pinhassi j. & not f. 2009. grazing rates and functional diversity of uncultured heterotrophic flagellates. isme journal 3, 588–596, doi: 10.1038/ismej.2008.130. mckenna s., meyer m., gregg c. & gerber s. 2016. s-corrplot: an interactive scatterplot for exploring correlation. journal of computational and graphical statistics 25, 445–463, doi: 10.1080/10618600.2015.1021926. monier a., sudek s., fast n.m. & worden a.z. 2013. gene invasion in distant eukaryotic lineages: discovery of mutually exclusive genetic elements reveals marine biodiversity. isme journal 7, 1764–1774, doi: 10.1038/ismej.2013.70. müller t.j. 2007. determination of salinity. in k. grasshoff et al. (eds.): methods of seawater analysis. 3rd edn. pp. 41–74. weinheim: wiley-vch. mylnikova z.m. & mylnikov a.p. 2012. structure of filose amoeba rhogostoma minus belar 1921 (cryomonadida, cercozoa) cell. inland water biology 5, 236–240, doi: 10.1134/s1995082912020101. orsi w., edgcomb v., jeon s., leslin c., bunge j., taylor g.t., varela r. & epstein s. 2011. protistan microbial observatory in the cariaco basin, caribbean. ii. habitat specialization. isme journal 5, 1357–1373, doi: 10.1038/ismej.2011.7. piwosz k. & pernthaler j. 2010. seasonal population dynamics and trophic role of planktonic nanoflagellates in coastal surface waters of the southern baltic sea. environmental microbiology 12, 364–377, doi: 10.1111/j.​1462-2920.2009.02074.x. piwosz k., wiktor j.m., niemi a., tatarek a. & michel c. 2013. mesoscale distribution and functional diversity of picoeukaryotes in the first-year sea ice of the canadian arctic. isme journal 7, 1461–1471, doi:10.1038/ismej.2013.39. pruesse e., quast c., knittel k., fuchs b.m., ludwig w., peplies j. & glockner f.o. 2007. silva: a comprehensive online resource for quality checked and aligned ribosomal rna sequence data compatible with arb. nucleic acids research 35, 7188–7196, doi: 10.1093/nar/gkm864. rodriguez-martinez r., rocap g., salazar g. & massana r. 2013. biogeography of the uncultured marine picoeukaryote mast-4: temperature-driven distribution patterns. isme journal 7, 1531–1543, doi: 10.1038/ismej.2013.53. schlitzer r., anderson r.f., dodas e.m., lohan m., geibere w., tagliabue a., bowie a., jeandel c., maldonado m.t., landing w.m., cockwell d., abadie c., abouchami w., achterberg e.p., agather a., aguliar-islas a., van aken h.m., andersen m., archer c., auro m., de baar h.j., baars o., baker a.r., bakker k., basak c., baskaran m., bates n.r., bauch d., van beek p., et al. 2018. the geotraces intermediate data product 2017. chemical geology 493, 210–223, doi: 10.1016/j.chemgeo.2018.05.040. schloss p.d., westcott s.l., ryabin t., hall j.r., hartmann m., hollister e.b., lesniewski r.a., oakley b.b., parks d.h., robinson c.j., sahl j.w., stres b., thallinger g.g., van horn d.j. & weber c.f. 2009. introducing mothur: open-source, platform-independent, community-supported software for describing and comparing microbial communities. applied environmental microbiology 75, 7537–7541, doi: 10.1128/aem.01541-09. seenivasan r., sausen n., medlin l.k. & melkonian m. 2013. picomonas judraskeda gen. et sp nov.: the first identified member of the picozoa phylum nov., a widespread group of picoeukaryotes, formerly known as “picobiliphytes.” plos one 8, article no. e59565, doi: 10.1371/journal.pone.0059565. sherr e.b. & sherr b.f. 2002. significance of predation by protists in aquatic microbial food webs. antonie van leeuwenhoek 81, 293–308, doi: 10.1023/a:1020591307260. sohrin r., imazawa m., fukuda h. & suzuki y. 2010. full-depth profiles of prokaryotes, heterotrophic nanoflagellates, and ciliates along a transect from the equatorial to the subarctic central pacific ocean. deep-sea research part ii 57, 15371–15350, doi: 10.1016/j.dsr2.2010.02.020. thaler m. & lovejoy c. 2012. distribution and diversity of a protist predator cryothecomonas (cercozoa) in arctic marine waters. journal of eukaryotic microbiology 59, 291–299, doi: 10.1111/j.1550-7408.2012.00631.x. thaler m. & lovejoy c. 2015. biogeography of heterotrophic flagellate populations indicates the presence of generalist and specialist taxa in the arctic ocean. applied environmental microbiology 81, 2137–2148, doi: 10.1128/aem.02737-14. waleron m., waleron k., vincent w.f. & wilmotte a. 2007. allochthonous inputs of riverine picocyanobacteria to coastal waters in the arctic ocean. fems microbiology ecology 59, 356–365, doi: 10.1111/j.1574-6941.2006.00236.x. zhang f., cao s.a., gao y. & he j.f. 2019. distribution and environmental correlations of picoeukaryotes in an arctic fjord (kongsfjorden, svalbard) during the summer. polar research 38, article no. 3390, doi: 10.33265/polar.v38.3390. zhang f., he j.f., lin l. & jin h.y. 2015. dominance of picophytoplankton in the newly open surface water of the central arctic ocean. polar biology 38, 1081–1089, doi: 10.1007/s00300-015-1662-7. synergy between behavioural research on beluga whales (delphinapterus leucas) conducted in zoological and wild settings research article synergy between behavioural research on beluga whales (delphinapterus leucas) conducted in zoological and wild settings heather m. manitzas hill1, deirdre b. yeater2 & michael noonan3 1psychology department, st. mary’s university, san antonio, tx, usa; 2psychology department, sacred heart university, fairfield, ct, usa; 3biology department, canisius college, buffalo, ny, usa abstract behavioural observations of captive beluga whales have complemented and extended much of what has been learnt about this species in the wild. aquarium-based research has provided finer-scale specificity for many topics, including the seasonal breeding pattern that is characteristic of this species, as well as socio-sexual behaviour that appears to be an important part of the behavioural repertoire of this species. one example is a strong propensity for male–male social interactions that begin to develop at an early age. in addition, detailed behavioural milestones in calves have been documented in ways that extend that which have been collected from wild populations. these include swim positions with mother, separations/reunions with mother, and other social interactions, and play. characteristics of beluga maternal care have also been studied more often in captive settings than in the wild, particularly with respect to details pertaining to nursing behaviour, individual differences in maternal style and allomaternal care. other topics that have received scientific scrutiny in zoological settings include individual differences and behavioural laterality. thus, a greater understanding of beluga behavioural biology has the potential to emerge as a consequence of synergy between research conducted in the two settings. keywords animal cognition; aquariums; captive whales; socio-sexual interactions; maternal behaviour; play   citation: polar research 2021, 40, 5508, http://dx.doi.org/10.33265/polar.v40.5508 copyright: polar research 2021. © 2021 h.m.m. hill et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 12 november 2021 competing interests and funding: the authors report no conflict of interest. no financial support was received for the conduct of the research reported here. mystic aquarium provided the fees for publication in the journal polar research. correspondence to: heather m. manitzas hill, psychology department, one camino santa maria, st. mary’s university, san antonio, tx 78228, usa. e-mail: hhill1@stmarytx.edu this article is part of the special cluster beluga whales (delphinapterus leucas): knowledge from the wild, human care and tek, which has been funded by mystic aquarium, caff and the norwegian ministry of climate and environment. introduction the beluga or white whale (delphinapterus leucas) is a gregarious species that is observed throughout the sub-arctic/arctic region (brodie 1971; sergeant 1973; boltunov & belikov 2002; loseto et al. 2006; chernetsky et al. 2011; krasnova et al. 2012; colbeck et al. 2013). while continuing to be important to subsistence hunters, belugas are now also considered to be a sentinel species for the overall health of the polar region (huntington et al. 1999; mymrin et al. 1999). as a consequence, the monitoring of beluga populations with regard to their migrations, foraging, calving and social interactions has become a critical activity for many governments and researchers. unfortunately, the remote and challenging nature of their natural habitat has limited most wild-based research to population counts, migration patterns and short-term behavioural observations that will be integrated throughout this review (e.g., brodie 1971; sergeant 1973; heide-jørgenson & teilmann 1994; o’corry-crowe et al. 1997; boltunov & belikov 2002; michaud 2005; loseto et al. 2006; chernetsky et al. 2011; krasnova et al. 2012; colbeck et al. 2013; o’corry-crowe et al. 2020). although belugas in zoological facilities are unable to express some portions of their behavioural repertoire (e.g., foraging and migrations), conducting research in such facilities offers a number of advantages. these advantages include (1) far greater accessibility of the animals, (2) greater visibility that allows the observation of critical details, like sequence of behaviours, initiators, receivers, body orientations, postures, eye directions, etc., and (3) the ability to follow individuals over long time frames to evaluate seasonal and life-span developmental changes. the purpose of this article is to review the behavioural research that has been conducted on belugas in zoological facilities, and to articulate the ways in which such research has complemented and extended that which has been learnt in the wild. social structure/affiliative behaviour in the wild, beluga social structure is often inferred to be a fission–fusion society in which individuals move into and out of each other’s company (i.e., godde et al. 2013). this inference has been driven by the tendency of most beluga populations to congregate in large mixed sex and age herds during summers, while at other times groups are observed that are comprised solely of adult males, solely of juveniles and loose association of mothers with calves (brodie 1971; sergeant 1973; heide-jørgenson & teilmann 1994; o’corry-crowe et al. 1997; boltunov & belikov 2002; michaud 2005; loseto et al. 2006; may-collado et al. 2007; chernetsky et al. 2011; krasnova et al. 2012; colbeck et al. 2013). most previous works on wild beluga populations have consisted of information about the size of social groupings, distribution movements, foraging and anecdotal information regarding affiliative interactions (brodie 1971; sergeant 1973; heide-jørgenson & teilmann 1994; o’corry-crowe et al. 1997; boltunov & belikov 2002; michaud 2005; loseto et al. 2006; may-collado et al. 2007; chernetsky et al. 2011; krasnova et al. 2012; colbeck et al. 2013). due to constraints of access and technology most studies with wild populations have focused on surface-based behaviour. more recently, with advances in technology, genetic evidence is elucidating the relationships between beluga social groups in over 10 different populations around the globe, indicating that both kin and non-kin individuals are observed together in various social groups (o’corry-crowe et al. 2020). by contrast, research in zoological institutions has provided much greater specificity. findings have included that male–male dyads are much more common than female–female dyads regardless of age (hill, garcia de oliveira silva-gruber et al. 2018; mazikowski et al. 2018). in one zoological population that included six males and 15 females, male–male adult dyads interacted at rates seven times that of female–female adult dyads (hill, garcia de oliveira silva-gruber et al. 2018). this pattern was recently replicated by research conducted at a second zoological facility consisting of five males and five females, which also demonstrated a seasonality effect (ham et al. 2021 [this special cluster]). male–male calf dyads, across two different zoological facilities, occurred almost four times more often than female–female calf dyads (mazikowski et al. 2018). mixed sex adult dyads and mixed sex calf dyads occurred but much less frequently (hill, garcia de oliveira silva-gruber et al. 2018; mazikowski et al. 2018). these patterns of affiliative swim associations based on proximity make it clear that male belugas prefer to spend time with male belugas as compared to female belugas, and that this preference appears to begin relatively early in development, emerging within the first three years of life (mazikowski et al. 2018). tactile behaviour behavioural observations of wild belugas have shown that when they swim in close proximity to one another, they often contact one another (huntington 2005; michaud 2005; alekseeva et al. 2013; krasnova et al. 2014). these observations have occurred primarily in shallow waters where large beluga congregations occur (e.g., cunningham inlet, g. freund, pers. comm., 2020). large white belugas, presumably males, have also been reported to both congregate together and display contact behaviour during seemingly affiliative interactions (alekseeva et al. 2013), and calves have been observed contacting each other and other larger belugas (krasnova et al. 2009; alekseeva et al. 2013; karenina et al. 2013; krasnova et al. 2014). when such tactile contact was assessed for a captive population of eight belugas using surface-based observations over an entire year, tactile contact between calves was frequent, while tactile contact between adult females was found to almost never occur (tactile contact between adult males could not be assessed [hill, alvarez et al. 2016]). similar trends were replicated when mother–calf dyads were examined using underwater video footage (hill, dietrich et al. 2018). more recently, an assessment of tactile contact among 47 belugas housed in larger social groupings have produced similar findings (unpublished data). in addition, evidence from a small number of beluga calves indicated that social interactions lasted longer when tactile contact occurred than when it did not (hill, dietrich et al. 2018). in all, these results suggest that the frequency of tactile contact between belugas is significantly influenced by age and sex. finally, the overall rates of contact are lower than what has been observed for delphinids in both zoological and wild settings (dudzinski et al. 2009; dudzinski et al. 2010; dudzinski & ribic 2017). follow-up studies underway by the present authors are exploring the distinction between proximity and contact as indices of sociality in belugas, and preliminary results suggest that very different roles may be played by interindividual physical closeness versus inter-individual touching in males versus females. additional investigations into the role of tactile contact during affiliative interactions will be critical for elucidating the function of touching in social behaviour. in most animal species, tactile contact is critical as a means by which to mediate relationships between individuals within a society (tamaki et al. 2006; dudzinski & ribic 2017; themelin et al. 2020), especially when the social structure is fission–fusion in nature as seems to be the case for most delphinids and perhaps for belugas. socio-sexual interactions socio-sexual interactions are non-conceptive social behaviours in which the genital region can be targeted but may also include a number of other behaviours that are adopted from sexual, conceptive contexts (furuichi et al. 2014). across multiple species, these interactions typically involve same-sex dyads or groups, but in cetaceans, such as delphinids, they can involve mixed sexes and ages (mann 2006; connor & krutzen 2015). socio-sexual interactions are thought to fulfil several functions, including practice for future reproductive sexual behaviour, development and maintenance of bonds, dominance and reconciliation, and may represent an exaptation of reproductive behaviour (vasey 1995). to date, socio-sexual behaviours by wild belugas have only been reported anecdotally (michaud 2005; alekseeva et al. 2013). the best example of socio-sexual behaviour in the wild is depicted in a series of aerial photographs captured during transect flyovers of the cook inlet, alaska, beluga population. several pairings of large white whales were observed in lateral presentations and side-by-side swims with various ‘s’ postures (lomac-macnair et al. 2015). images like these are valuable, but they are missing critical information, such as the sex and age of the dyad members. without information about the individuals, the context and/or function are speculative at best. by contrast, in zoological facilities these kinds of social interactions can be studied year-round, assuming the social groupings are appropriate to elicit the behaviours of interest. data collected from three different us-based zoological facilities demonstrated that socio-sexual behaviours were more likely to occur between adult–sub-adult male dyads, adult-male–juvenile dyads and calf–calf or juvenile–juvenile dyads (hill, dietrich et al. 2015). reciprocated, lateral swims, extended pectoral fins, bubble trails, ‘s’ postures with the genital region pushed forward and pelvic thrusts are common socio-sexual behaviours (see figure 1 in hill, dietrich et al. 2015), with pelvic thrusts and mouthing having the greatest opportunity for tactile contact. in calves studied at one facility, socio-sexual behaviour did not clearly emerge until about three years of age, the age also associated with first observation of calf erections (hill, dietrich et al. 2015). thus, some socio-sexual behaviours, such as genital rubs and genital contact, occur early in belugas but not as frequently as seen in bottlenose dolphins (kuczaj et al. 2006; mann 2006). more recent work on the development of socio-sexual behaviours beyond the calf stage has shown how the behaviours become more organized with age (lilley et al. 2020). additionally, seasonal variation in socio-sexual behaviour becomes more predictable as the calves age into sub-adults and adults (ham et al. 2021 [this special cluster]). female belugas do not seem to engage in socio-sexual interactions once sexually mature (glabicky et al. 2010; hill, dietrich et al. 2015), but they will engage in socio-sexual behaviours and interactions as calves, despite not displaying all behaviours within the socio-sexual repertoire (hill, dietrich et al. 2015; lilley et al. 2020). developmental work conducted across several facilities has demonstrated the importance of male–male bonds and mixed age and sex social groupings to both facilitate the expression of the behavioural repertoire and diversify behaviours (hill & ramirez 2014; hill, guarino et al. 2015; hill, garcia de oliveira silva-gruber et al. 2018; mazikowski et al. 2018; lilley et al. 2020). preliminary evidence from an ongoing study by the present authors documenting tactile contact in 47 belugas housed at one facility supports this impression as female calves rarely experienced direct genital contact or initiated genital contact, despite receiving genital contact on other parts of their bodies. clearly, more research is needed to clarify the function of socio-sexual interactions, as is also the case for most cetacean species (bailey & zuk 2009). courtship and reproductive interactions the courtship and reproductive behaviours of belugas have also not been systematically studied in any wild beluga population. while mixed sex social groupings have been reported, mating attempts and courtship behaviours have only been occasionally observed (chernetsky et al. 2011; krasnova et al. 2012; alekseeva et al. 2013). studying these behaviours in the wild from surface-based observations is challenging as it requires clear, calm water, identified individuals and the ability to follow the behaviour sequence for each interactant. michaud, a prominent beluga expert, wrote that after more than 20 years of boat time and thousands of surface observations, he had only observed only “five mating attempts, one possible birth, no nursing” (2005: 303). in the wild, mating seasons have been estimated from physiological evidence (testis size or foetal age from deceased animals), estimated calf age during population counts, and traditional knowledge shared by subsistence hunters (e.g., huntington et al. 1999; mymrin et al. 1999; chernetsky et al. 2011; krasnova et al. 2012; alekseeva et al. 2013; shelden et al. 2019). based on this aggregated knowledge, it is clear that belugas are seasonal breeders, with peak breeding season estimated to fall between march and june (huntington et al. 1999; chernetsky et al. 2011; krasnova et al. 2012; alekseeva et al. 2013; shelden et al. 2019). research conducted with belugas at several different zoological facilities has also documented a seasonal increase in male–female interactions that corresponds to a breeding season. glabicky et al. (2010) documented that male-to-female genital thrusts peaked in frequency in march, with reductions to near-zero levels following the end of the breeding season. these seasonal interactions have been corroborated with increases in reproductive hormones for both sexes (robeck et al. 2005; richard et al. 2021 [this special cluster]). details of the behavioural components of courtship were first described by recchia (1994) in her dissertation on the social behaviour of belugas at several different facilities and included into an interactive computer-based ethogram constructed for another facility (dipaola et al. 2007). an even more detailed catalogue of courtship, reproduction, socio-sexual and agonistic behaviours was created from multiple sources of information including previous papers and personal observations (hill, dietrich et al. 2015). many of the behaviours observed overlapped different social behaviour categories. however, the context did elicit subtle differences in topographies. for example, males (and females) often display ‘s’ postures that can either be held briefly while stationary in the water or dynamically moved through in transition to a pelvic thrust (hill, dietrich et al. 2015; lilley et al. 2020). however, an important insight gained from such captivity-based research is that, depending on the position of the pelvic region, the ‘s’ posture can be a sign of courtship, socio-sexual behaviour or agonism (horback et al. 2010; hill, dietrich et al. 2015). other behaviours that appear to be part of the male courtship repertoire are directed gazes, following, synchronous swims in close proximity to the female, bubble trails and perhaps mouthing (hill, dietrich et al. 2015). subsequent studies, some of which are in progress, are expanding our understanding of beluga courtship by (1) investigating a suspected diel rhythm in mating behaviour, (2) detailing the specific sequence in which such behaviours typically occur, (3) uncovering how such behaviours vary as a function of group size and composition, and (4) identifying the complementary roles played by the two sexes. preliminary indications are that it is common for more than one male to approach a potentially receptive female in an apparently cooperative fashion, and that the female plays a significant role in determining which of the males ultimately achieves copulation. this topic represents a gap in knowledge that is particularly relevant for the conservation of depleted wild populations (e.g., cook inlet, alaska, and st. lawrence, quebec). mother–calf interactions research conducted in the wild has documented preferred habitats for mothers and calves (e.g., huntington et al. 1999; mymrin et al. 1999; chernetsky et al. 2011; mcguire et al. 2020). beyond that, most of the available knowledge about interactions between beluga mothers and calves in wild populations has been derived from the beluga population found in the white sea, where research has been ongoing every summer since the mid-1990s (krasnova et al. 2006, 2009; krasnova et al. 2014). in this population, beluga mothers and their calves maintain their association for an average of two years and older, weaned offspring remain with the natal group. reported interactions between mother belugas and their calves have included separations, reunions, species-specific, age-specific and lateralized swim positions, nursing, play, affiliative contact and the disciplining of the calf (krasnova et al. 2003; krasnova et al. 2006; karenina et al. 2010; karenina et al. 2013; krasnova et al. 2014). beluga calves appear to show early independence from their mothers, separating and interacting with other calves or other females within two months of life (krasnova et al. 2014). this early autonomy may be mediated by contact calls that appear to contain information about individual identity (vergara et al. 2010; vergara & mikus 2019). the emergence of similarly early independence has been reported for cook inlet belugas (t. mcguire, pers comm.). interestingly, while mothers and calves tend to be segregated from adult males in the white sea (krasnova et al. 2009; krasnova et al. 2014), mothers and calves are often found in mixed sex and age social groupings in cook inlet (mcguire et al. 2020). the opportunity to closely observe mothers and their calves through underwater windows is unique to zoological facilities, and it offers unparalleled opportunities that even the best conditions in the wild cannot match. aquarium-based work that is ongoing by the authors indicates that it is common for a parturient female to distance herself from other whales during most of her labour. as the time of birth gets close, other adult females characteristically swim very close to her, and it is they who usually first push the neonate to the surface when it is delivered. details about this perinatal behaviour are forthcoming. maternal behaviours such as disciplining the calf, intervening in its activity and calf monitoring activities have suggested consistent individual differences in maternal styles (hill 2009; hill et al. 2013). contact between mothers and calves, which is mostly initiated by calves, appears to facilitate the development of their bond (hill, dietrich et al. 2018). additionally, recent preliminary analysis of 21 mother–calf pairs has suggested that mothers may have varying rates of initiation of contact with their calves. this information may clarify differences in maternal style and long-term outcomes of calf success. allomothering the apparent care of young belugas by other belugas that are not their mothers has been reported in several wild populations (e.g., krasnova et al. 2014). although such reports have only been anecdotal and the observations fleeting, they raise the possibility that allocare may be a normal part of the beluga behavioural repertoire. as a possible confirmation of that, one zoology-based study found that allocare interactions occurred for several calves when sub-adult or adult nulliparous females were available (hill & campbell 2014). until researchers can differentiate biological mothers in the wild from allomothers few conclusions can be drawn from these observations. developmental landmarks the importance of fully understanding the behavioural development of beluga calves was illustrated by the challenges faced when a very young beluga calf live-stranded in 2017 near the town of tyonek, alaska, and local officials assessed the prospects for the stranded calf (shelden et al. 2019). despite the fact that numerous stocks of wild belugas had been monitored for years, there were very little specific data stemming from wild populations about developmental landmarks against which to compare the status of the stranded calf. fortunately, however, there was already a great deal of pertinent information stemming from research in captivity. behavioural developmental milestones, such as initiation of separations, initiation of reunions, swim positions, nursing, play, social interactions, motor development, attention to environment and vocal development, had all been established (vergara & barrett-lennard 2008; hill 2009; leung et al. 2010; hill et al. 2013; hill & campbell 2014; brown 2018; ames & vergara 2020). as a result, an ad hoc consortium of personnel with expertise from wild and zoological settings was able to craft a successful rescue/rehabilitation programme (goertz et al. 2019). this case study was a particularly good example of the kind of synergy that is possible between wildlife researchers and those studying belugas in zoological facilities. in this regard, it should be noted that even more recently complementary findings have been obtained via very important longitudinal work that has been conducted on calves in the critically endangered beluga population of cook inlet (mcguire et al. 2020). researchers from both areas should continue to collaborate on these types of studies. play behaviour play is important for both cognitive and social development in many social species, and cetacean species of all ages have been reported to play (paulos et al. 2010; hill et al. 2017). consistent with this generalization, krasnova et al. (2009) reported that white sea beluga calves engaged in locomotor play and imitation of older juveniles. one specific example reported anecdotally by krasnova et al. (2014) included two juvenile belugas in the white sea engaging in a mouth-to-mouth interaction. more detailed studies in captivity have expanded upon those observations and add to the growing evidence for certain types of social play, such as mouth-to-mouth social play (hill, dietrich et al. 2019). hill & ramirez (2014) demonstrated that in addition to calves and juveniles, adult belugas also engaged in play behaviours; males engaged in more play bouts and a higher percentage of locomotor play activities. hill, guarino et al. (2015) found that young belugas interacting with adults lead to a greater diversity of behaviours. direction and duration of gaze borrowing a technique that has long been employed in the study of human babies (e.g., baillargeon et al. 2015), animal researchers have been tracking the direction and duration of gaze as windows into the perceptual abilities and selective attention of their animal subjects. along these lines, karenina et al. (2010) found that wild belugas tend to view novel objects for longer periods than familiar objects. similarly, they exhibited longer gaze durations when viewing unfamiliar people. in an extension to that study in captivity, hill, yeater et al. (2016) also found that belugas looked longer at unfamiliar humans, regardless of their clothing (standardized or uniforms). the captive belugas also exhibited a longer gaze duration for active humans rather than stationary ones. guarino et al. (2017) and yeater et al. (2017) further confirmed that unfamiliar objects elicited longer gaze durations than familiar ones. even more recently, individual differences were found in gaze length when both classes of stimuli, humans and objects, were combined and presented using a violation of expectation paradigm with an ‘unexpected’ change in stimuli (halter, yeater & manitzas hill, unpubl. ms). laterality in the wild, beluga calves were observed demonstrating a left-eye bias while maintaining social contact with their mothers (karenina et al. 2013). in addition, wild belugas were found to view novel objects underwater more often using their left eye (karenina et al. 2010). both of these findings suggest a hemispheric asymmetry in belugas. that inference that has been supported by follow-up studies conducted in captivity. when studying 12 belugas across multiple zoological facilities both yeater et al. (2014) and hill, yeater et al. (2016) found lateralized eye preferences at the individual level. in an extension of this line of research, guarino et al. (2017) and yeater et al. (2017) found that belugas tended to view both familiar and novel objects using both eyes, but that they demonstrated a left eye preference when monocular vision was used. in combination, these findings suggest a right hemisphere (left eye) specialization for visual processing of object and social stimuli. individual differences/behavioural syndromes in important ways, variations among individuals within a population provide the fuel that drives the engine of natural selection. a complete understanding of belugas must therefore also include the study of individual differences. some have suggested that personality-based responses to various anthropogenic events (e.g., boats, pile-driving and presence of humans) or novel stimuli provided experimentally by researchers (e.g., siniscalchi et al. 2012) can be evaluated in the wild (e.g., highfill & kuczaj 2010). unfortunately, to our knowledge, these studies have not yet made it to the peer-reviewed literature (e.g., skrzypczak 2016). at the second international workshop on beluga whale research and conservation held at mystic aquarium, mystic, connecticut, usa, in march 2019, an observation was shared that some belugas had been recaptured more often than others during sensor-placement tagging events, which led to some discussion about the role of personality in those repeated tagging events (h.m. manitzas hill, pers. obs.). similarly, anecdotes have been shared about free-ranging belugas that suggest individual variation in the degree of maternal permissiveness and attention (t. mcguire, pers. comm.). these speculations notwithstanding, consistent behavioural/personality ratings require frequent observations of the same individual, a requirement that is rarely achievable in the wild. in addition, care must be taken to avoid biasing data as bolder, more neophilic or naive animals may be more likely to be observable while more timid, neophobic or experienced animals may be less likely to be observable (richard et al. 2001). a major advance on this topic was achieved in a recent study that was conducted on 41 captive belugas of mixed sex and age. stable individual differences were found for 19 of 23 separate measures. these measures included 10 characteristics rated by trainers, and 13 spontaneous behaviours assessed by trained observers. inter-rater and inter-time reliability were consistent and moderately strong, suggesting that belugas exhibit stable individual differences in various aspects of their behaviour that can be detected reliably across raters and over time, and a pattern of cross-trait correlation suggested the possibility that behavioural dispositions may cluster in ways that constitute behavioural syndromes (hill, woodruff et al. 2019). additionally, beluga play behaviour and maternal care have received some attention in terms of individual differences in belugas in zoological facilities (hill et al. 2013; hill, guarino et al. 2015). preferences of play behaviours and frequency of play emerged for a socially dynamic population at a us facility (hill, guarino et al. 2015), where variations in maternal care behaviours were also documented (hill et al. 2013). following this, brown (2018) explored the development of temperament in seven calves from birth to two years by examining 40 different spontaneous behaviours. the findings indicated that a five-factor model was the best solution, which included mother–calf bond, sociability, independence, exploration–vigilance and curiosity–playfulness. cognitive processes one advantage of aquarium-based settings is that it offers researchers the ability to manipulate variables in experimental studies under controlled conditions. this allows more precise conclusions to be drawn than those possible from studies that are solely observational. this is a particularly important factor in cognitive studies. in one example of this kind of experiment, a captive beluga ‘labelled’ objects by matching a sample sounds with objects (tsukasa et al. 2012). murayama et al. (2017) found this same beluga also passed a test of transitivity. moreover, the beluga was able to identify the symmetrical relations across modalities (visual and auditory). in other work, abramson et al. (2013) demonstrated that a beluga could make relative quantity judgements by choosing a larger quantity above chance levels. additional studies underway by the present authors include experiments on social learning, tool use, creativity and executive functioning during information processing. discussion as this review shows, belugas in aquariums exhibit many behaviours that match those observed in their wild counterparts. it is also clear that, because of the greater opportunities for sustained observations, investigations conducted in zoological institutions can help to inform observations made in the wild. (table 1 provides a summary of the 12 topics reviewed above, along with key references.) to give just one example, lomac-macnair et al. (2015) reported summertime aerial observations over cook inlet of a pair of belugas making ventral–ventral contact, which lomac-macnair et al. interpreted as a male–female sexual event. however, aquarium-based findings (glabicky et al. 2010) document that beluga mating behaviour is highly seasonal, male–female contact is very rare outside of season and male–male pelvic contact is quite common during the summer, making it much more likely that the observation reported by lomac-macnair et al. (2015) was an instance of male–male socio-sexual contact. this illustrates how lengthy observations of captive animals may illuminate much briefer observations made on wild animals and demonstrates how information gained in the two settings might combine to direct future research. table 1 behavioural characteristics of beluga whales: comparison of observations obtained in the wild and observations obtained in zoological facilities. observations obtained from the wild key references from the wild observations obtained from zoological facilities key references from zoological facilities remaining questions social structure/affiliative behaviour reports of short-term associations, shallow-water interactions, and calf–adult interactions reports that adult males swim separately from females during part of the year huntington 2005; michaud 2005; loseto et al. 2006; chernetsky et al. 2011; krasnova et al. 2012; alekseeva et al. 2013; krasnova et al. 2014; o’corrycrowe et al. 2020 clear male–male associations during most of the year, in both adult and immature belugas far fewer close associations in females seasonal effects hill et al. 2018; mazikowski et al. 2018; ham et al. 2021 functional role for male–male associations? functional role of long-term associations? tactile behaviour anecdotal reports of occasional touching alekseeva et al. 2013; krasnova et al. 2009 sustained observations of known individuals reveal clear age and sex differences hill et al. 2016; hill, dietrich et al. 2018 functional role of touching? influence of kinship? socio-sexual behaviour anecdotal reports of genital contact outside of breeding season michaud 2005; alekseeva et al. 2013; lomac-macnair et al. 2015 identified behavioural repertoire development sequence from birth to adulthood same sex bias glabicky et al. 2010; horback et al. 2010; hill, dietrich et al. 2015; lilley et al. 2020 functional role of same-socio-sexual contact? courtship/reproductive behaviour seasonality inferred from the timing of male–female associations (and from gonadal measurements in deceased animals) anecdotal reports of fleeting male–female contact huntington et al. 1999; chernetsky et al. 2011; krasnova et al. 2012; alekseeva et al. 2013; lomac-macnair et al. 2015; shelden et al. 2019 seasonality confirmed from direct observation of mating detailed behavioural repertoire partial understanding of developmental time course glabicky et al. 2010; hill, dietrich et al. 2015; lilley et al. 2020; richard et al. 2021 sequence of courtship behaviours? differential roles by males and females in mate choice? mother–calf interactions preferred habitat for mother–calf pairs length of association anecdotal descriptions of behaviours huntington et al. 1999; mymrin et al. 1999; krasnova et al. 2003; krasnova et al. 2006; karenina et al. 2010; chernetsky et al. 2011; karenina et al. 2013; krasnova et al. 2014; mcguire et al. 2020 behavioural milestones as a function of calf age specific types of tactile interactions social interactions outside the mother–calf dyad vergara & barrett-lennard 2008; hill 2009; leung et al. 2010; vergara et al. 2010; hill et al. 2013; hill & campbell 2014; hill et al. 2016; hill, dietrich et al. 2018; vergara & mikus 2019; ames & vergara 2020 length of association as a function of social structure? mechanism for mother–calf recognition? mother–calf cultural transmission? long-term relationships? does intergenerational maternal care occur? allomothering anecdotal evidence reported from the white sea krasnova et al. 2014 documented instances of allocare hill & campbell 2014 ascertaining whether allocare occurs in the wild? if so, how frequently? developmental landmarks swim positions reported for neonates and yearlings krasnova et al. 2006 documented behavioural landmarks associated with age in beluga calves hill 2009; hill et al. 2013; hill & campbell 2014 associating behavioural landmarks with specific ages in wild populations? play behaviour a few anecdotal reports of apparent play behaviour, more common in immature belugas, but also sometimes observed in adults krasnova et al. 2009; krasnova et al 2012; krasnova et al 2014; alekseeva et al. 2013 developmental progression of play behaviour in calves importance of play for young animals in social groups variation in play behaviour across individuals hill & ramirez 2014; jones & kuczaj 2014; hill, guarino et al. 2015; hill et al. 2019 adaptive value of play in natural settings? gaze direction/duration anecdotal reports of apparent looking at novel stimuli karenina et al. 2010 longer gazes at novel/unfamiliar stimuli hill et al. 2016; guarino et al. 2017 adaptive value of curiosity in wild settings? laterality observations of laterality in mother–calf swim positions, and in responses to novel objects karenina et al. 2010; karenina et al. 2013 similar observations of lateralized orientations between mothers and calves lateralized responses to objects and to humans based on familiarity yeater et al. 2014; hill, yeater et al. 2016; hill, guarino et al. 2017; yeater et al. 2017 functional role of laterality vis-à-vis environmental and social stimuli? individual differences a few anecdotal reports krasnova et al. 2009; krasnova et al. 2012; krasnova et al. 2014 evidence of reliable individual differences on multiple measures, suggestive of behavioural syndromes hill et al. 2013; hill, guarino et al. 2015; brown 2018; hill et al. 2019 need to develop procedures for following individual belugas in the wild? cognitive processes nothing reported sound mimicry perception of quantity behavioural imitation tsukasa et al. 2012; abramson et al. 2013; murayama et al. 2017 adaptive value of cognitive processes in the wild? while captive facilities continue to implement modifications in structure, social groupings and enrichment that allow for more and more natural behaviour, it must be recognized that captive animals inevitably face behavioural restrictions, particularly for large-scale behaviours, such as long-distance movements and foraging. studies in the wild will always be the primary means by which information is obtained about animals moving freely. nevertheless, it is argued here that the more specific knowledge gained from aquarium-based research can guide future behavioural observations in the wild. the study of individual differences is an example. not only does this topic have clear relevance for the survival and reproductive fitness of many animals (smith & blumstein 2008; sargeant & mann 2009), knowledge of individual characteristics has also implications for social grouping management and reproductive compatibility both in the wild and in zoological facilities (highfill & kuczaj 2007, 2010; frick et al. 2017). measurable behaviours, operational definitions, rating scales and tests of various components of personality (e.g., neophobia, curiosity) are outcomes of captive-based research that could inform research on wild belugas. it should also be emphasized that the reverse should also be true. it is critically important that captive facilities keep abreast of advances in understanding the ecology of the animals that are in managed care. as more and more research is conducted on the social compositions and social interactions of wild belugas, the resulting knowledge will be useful for informing decisions made by managers of belugas in aquarium settings. over the last 10 years, zoological facilities have strived to maintain groupings that increasingly match the social structures seen in belugas in their natural habitat: male-only groups, mothers and their calves, adult females with some adult males, and a mixed age and sex social grouping. it is hoped that wild-based and aquarium-based studies will increasingly be mutually informative, moving towards a collaborative synergy that takes advantage of the strengths of each setting to promote beluga conservation in the wild and better welfare in captivity. acknowledgements the authors gratefully acknowledge the hospitality of georgia aquarium, marineland of canada, mystic aquarium, sea world san antonio, sea world san diego and shedd aquarium for their support of the ongoing research by the authors. they also thank to jackson ham and malin lilley, who provided helpful reviews of an early manuscript. references abramson j.z., hernández-lloreda v., call j. & colmenares f. 2013. relative quantity judgments in the beluga whale (delphinapterus leucas) and the bottlenose dolphin (tursiops truncatus). behavioural processes 96, 11–19, doi: 10.1016/j.beproc.2013.02.006. alekseeva y.i., panova e.m. & bel’kovich v.m. 2013. behavioral and acoustical characteristics of the reproductive gathering of beluga whales (delphinapterus leucas) in the vicinity of myagostrov, golyi sosnovets, and roganka islands (onega bay, the white sea). biology bulletin 40, 307–317, doi: 10.1134/s1062359013030023. ames a.e. & vergara v. 2020. trajectories of vocal repertoire development in beluga (delphinapterus leucas) calves: insights from studies a decade apart. aquatic mammals 46, 344–366, doi: 10.1578/am.46.4.2020.344. bailey n.w. & zuk m. 2009. same-sex sexual behavior and evolution. trends in ecology & evolution 24, 439–446, doi: 10.1016/j.tree.2009.03.014. baillargeon r., scott r.m., he z., sloane s., setoh p., jin k.-s., wu d. & bian l. 2015. psychological and sociomoral reasoning in infancy. in m. mikulinceret al. (eds.): apa handbook of personality and social psychology. vol. 1. attitudes and social cognition. pp. 79–150. washington, dc: american psychological association. boltunov a.n. & belikov s.e. 2002. belugas (delphinapterus leucas) of the barents, kara and laptev seas. nammco scientific publications 4, 149–168, doi: 10.7557/3.2842. brodie p.f. 1971. a reconsideration of aspects of growth, reproduction, and behavior of the white whale (delphinapterus leucas), with reference to the cumberland sound, baffin island, population. journal of the fisheries board of canada 28, 1309–1318, doi: 10.1139/f71-198. brown b. 2018. exploring temperament in beluga whale calves (delphinapterus leucas). phd thesis, university of southern mississippi. chernetsky a.d., krasnova v.v. & bel’kovich v.m. 2011. studies of the structure of the solovetsky reproductive gathering of beluga whales (delphinapterus leucas) in the white sea using the photo identification method. oceanology 51, 275–280, doi: 10.1134/s0001437011020044. colbeck g.j., duchesne p., postma l.d., lesage v., hammill m.o. & turgeon j. 2013. groups of related belugas (delphinapterus leucas) travel together during their seasonal migrations in and around hudson bay. proceedings of the royal society biology 280, 2552–2561, doi: 10.1098/rspb.2012.2552. connor r.c. & krützen m. 2015. male dolphin alliances in shark bay: changing perspectives in a 30-year study. animal behaviour 103, 223–235, doi: 10.1016/j.anbehav.2015.02.019. dipaola s., akai c. & kraus b. 2007. experiencing belugas: action selection for an interactive aquarium exhibit. adaptive behavior 15, 99–113, doi: 10.1177/1059712306076251. dudzinski k., gregg j., paulos r.d. & kuczaj s.a. 2010. a comparison of pectoral fin contact for three distinct dolphin populations. behavioural processes 84, 559–567, doi: 10.1016/j.beproc.2010.02.013. dudzinski k., gregg j., ribic c. & kuczaj s. 2009. a comparison of pectoral fin contact between two different wild dolphin populations. behavioural processes 80, 182–190, doi: 10.1016/j.beproc.2008.11.011. dudzinski k.m. & ribic c.a. 2017. pectoral fin contact as a mechanism for social bonding among dolphins. animal behavior and cognition 4, 30–48, doi: 10.12966/abc.03.02.2017. frick e.e., de vere a.j. & kuczaj s.a. 2017. what do we want to know about personality in marine mammals? in j. vonket al. (eds.): personality in nonhuman animals. pp. 237–253. cham, switzerland: springer. furuichi t., connor r. & hashimoto c. 2014. non-conceptive sexual interactions in monkeys, apes, and dolphins. in j. yamagiwa & l. karczmarski (eds.): primates and cetaceans. pp. 385–408. tokyo: springer. glabicky n., dubrava a. & noonan m. 2010. social–sexual behavior seasonality in captive beluga whales (delphinapterus leucas). polar biology 33, 1145–1147, doi: 10.1007/s00300-010-0790-3. godde s., humbert l., côté s.d., réale d. & whitehead h. 2013. correcting for the impact of gregariousness in social network analyses. animal behaviour 85, 553–558, doi: 10.1016/j.anbehav.2012.12.010. goertz c.e., burek-huntington k., royer k., quakenbush l., clauss t., hobbs r. & kellar n. m. 2019. comparing progesterone in blubber and serum to assess pregnancy in wild beluga whales (delphinapterus leucas). conservation physiology 7, article no. coz071, doi: 10.1093/conphys/coz071. guarino s., yeater d., lacy s., dees t. & hill h. 2017. responses to familiar and unfamiliar objects by belugas (delphinapterus leucas), bottlenose dolphins (tursiops truncatus), and pacific white-sided dolphins (lagenorhynchus obliquidens). animal cognition 20, 823–827, doi: 10.1007/s10071-017-1103-9. ham j.r., lilley m.k. & manitzas hill h.m. 2021. seasonality of social behaviour among immature belugas (delphinapterus leucas) in managed care. polar research 40, article no. 5498, doi: 10.33265/polar.v40.5498 heide-jørgensen m.p. & teilmann j. 1994. growth, reproduction, age structure and feeding habits of white whales (delphinapterus leucas) in west greenland waters. meddelelser om grønland bioscience 39, 195–212. highfill l.e. & kuczaj s.a. 2007. do bottlenose dolphins (tursiops truncatus) have distinct and stable personalities? aquatic mammals 33, 380–389, doi: 10.1578/am.33.3.2007.387. highfill l.e. & kuczaj s.a. 2010. how studies of wild and captive dolphins contribute to our understanding of individual differences and personality. international journal of comparative psychology 23, 269–277. hill h. 2009. the behavioral development of two beluga calves during the first year of life. international journal of comparative psychology 22, 234–253. hill h., alvarez c., dietrich s. & lacy k. 2016. preliminary findings in beluga (delphinapterus leucas) tactile interactions. aquatic mammals 42, 277–291, doi: 10.1578/am.42.3.2016.277. hill h. & campbell c. 2014. allocare depends on social composition for belugas (delphinapterus leucas) in human care. international journal of comparative psychology 27, 501–514, doi: 10.46867/ijcp.2014.27.04.08. hill h., campbell c., dalton l. & osborn s. 2013. the first year of behavioral development and maternal care of beluga (delphinapterus leucas) calves in human care. zoo biology 32, 565–570, doi: 10.1002/zoo.21093. hill h., dietrich s., finn r., garza s., alvarez c., lacy k. & kuczaj s. 2018. role of contact in beluga (delphinapterus leucas) calf relationships. aquatic mammals 44, 62–75, doi: 10.1578/am.44.1.2018.62. hill h., dietrich s., yeater d., mckinnon m., miller m., aibel s. & dove a. 2015. developing a catalog of sexual and socio-sexual behaviors of beluga whales in the care of humans. animal behavior and cognition 2, 105–123, doi: 10.12966/abc.05.01.2015. hill h., guarino s., crandall s., lenhart e. & dietrich s. 2015. young belugas diversify adult beluga (delphinapterus leucas) behavior. animal behavior and cognition 2, 267–284, doi: 10.12966/abc.08.06.2015. hill h. & ramirez d. 2014. adults play but not like their young: the frequency and types of play by belugas (delphinapterus leucas) in human care. animal behavior and cognition 1, 166–185, doi: 10.12966/abc.05.07.2014. hill h.m., dietrich s. & cappiello b. 2017. learning to play: a review and theoretical investigation of the developmental mechanisms and functions of cetacean play. learning & behavior 45, 335–354, doi: 10.3758/s13420-017-0291-0. hill h.m., dietrich s., guarino s., banda m. & lacy k. 2019. preliminary observations of an unusual mouth interaction between beluga calves (delphinapterus leucas). zoo biology 38, 149–156, doi: 10.1002/zoo.21463. hill h.m., garcia de oliveira silva-gruber d. & noonan m. 2018. sex-specific social affiliation in captive beluga whales (delphinapterus leucas). aquatic mammals 44, 250–255, doi: 10.1578/am.44.3.2018.250. hill h.m., guarino s., calvillo a., gonzalez a., zuniga k., bellows c., polasek l. & sims c. 2017. lateralized swim positions are conserved across environments for beluga (delphinapterus leucas) mother–calf pairs. behavioural processes 138, 22–28, doi: 10.1016/j.beproc.2017.01.018. hill h.m., woodruff m.j. & noonan m. 2019. individual differences in the behavioral characteristics of beluga whales (delphinapterus leucas). behavioural processes 166, article no. 103885, doi: 10.1016/j.beproc.2019.06.008. hill h.m., yeater d., gallup s., guarino s., lacy s., dees t. & kuczaj s. 2016. responses to familiar and unfamiliar humans by belugas (delphinapterus leucas), bottlenose dolphins (tursiops truncatus), & pacific white-sided dolphins (lagenorhynchus obliquidens): a replication and extension. international journal of comparative psychology 29, article no. 32012. horback k.m., friedman w.r. & johnson c.m. 2010. the occurrence and context of s-posture display by captive belugas (delphinapterus leucas). international journal of comparative psychology 23, 689–700. huntington h.p. 2005. “we dance around in a ring and suppose”: academic engagement with traditional knowledge. arctic anthropology 42, 29–32, doi: 10.1353/arc.2011.0101. huntington h.p. & communities of buckland, elim, koyuk, point lay and shaktoolik 1999. traditional knowledge of the ecology of beluga whales (delphinapterus leucas) in the eastern chukchi and northern bering seas, alaska. arctic 52, 49–61, doi: 10.14430/arctic909. jones b.l. & kuczaj s.a. 2014. beluga (delphinapterus leucas) novel bubble helix play behavior. animal behavior and cognition 1, 206–214, doi: 10.12966/abc.05.10.2014. karenina k., giljov a., baranov v., osipova l., krasnova v. & malashichev y. 2010. visual laterality of calf–mother interactions in wild whales. plos one 5, e13787, doi: 10.1371/journal.pone.0013787. karenina k., giljov a., glazov d. & malashichev y. 2013. social laterality in wild beluga whale infants: comparisons between locations, escort conditions, and ages. behavioral ecology and sociobiology 67, 1195–1204, doi: 10.1007/s00265-013-1545-2. krasnova v., belkovich v. & chernetsky a. 2003. dynamics of belugas (delphinapterus leucas) behavior in reproduction gathering. in p.g.h. evanset al. (eds.): proceedings of the seventeenth annual conference of the european cetacean society, las palmas de gran canaria, canary islands, spain, 9–13 march 2002. pp. 130–139. european cetacean society. krasnova v.v., bel’kovich v.m. & chernetsky a.d. 2006. mother–infant spatial relations in wild beluga (delphinapterus leucas) during postnatal development under natural conditions. biology bulletin 33, 53–58, doi: 10.1134/s1062359006010079. krasnova v.v., bel’kovich v.m. & chernetsky a.d. 2009. formation of behavior in the white sea beluga calf, delphinapterus leucas, during early postnatal ontogenesis. russian journal of marine biology 35, 53–59, doi: 10.1134/s1063074009010088. krasnova v.v., chernetsky a.d., kirillova o.i. & bel’kovich v.m. 2012. the dynamics of the abundance, age, and sex structure of the solovetsky reproductive gathering of the beluga whale delphinapterus leucas (onega bay, white sea). russian journal of marine biology 38, 218–225, doi: 10.1134/s1063074012030078. krasnova v.v., chernetsky a.d., zheludkova a.i. & bel’kovich v.m. 2014. parental behavior of the beluga whale (delphinapterus leucas) in natural environment. biology bulletin 41, 349–356, doi: 10.1134/s1062359014040062. kuczaj s.a., makecha r., trone m., paulos r.d. & ramos j.a. 2006. role of peers in cultural innovation and cultural transmission: evidence from the play of dolphin calves. international journal of comparative psychology 19, 223–240. leung e.s., vergara v. & barrett‐lennard l.g. 2010. allonursing in captive belugas (delphinapterus leucas). zoo biology 29, 633–637, doi: 10.1002/zoo.20295. lilley m.k., ham j.r. & hill h.m. 2020. the development of socio-sexual behavior in belugas (delphinapterus leucas) under human care. behavioural processes 171, article no. 104025, doi: 10.1016/j.beproc.2019.104025. lomac-macnair k.s., smultea m.a., cotter, m.p., thissen c. & parker l. 2015. socio-sexual and probable mating behavior of cook inlet beluga whales, delphinapterus leucas, observed from an aircraft. marine fisheries review 77, 32–39, doi: 10.7755/mfr.77.2.2. loseto l.l., richard p., stern g.a., orr j. & ferguson s.h. 2006. segregation of beaufort sea beluga whales during the open-water season. canadian journal of zoology 84, 1743–1751, doi: 10.1139/z06-160. mann j. 2006. male–male bonds among indian ocean bottlenose dolphins. in v. sommer & p.l. vasey (eds.): homosexual behaviour in animals: an evolutionary perspective. pp. 107–130. cambridge: cambridge university press. may-collado l.j., agnarsson i. & wartzok d. 2007. phylogenetic review of tonal sound production in whales in relation to sociality. bmc evolutionary biology 7, article no. 136, doi: 10.1186/1471-2148-7-136. mazikowski l., hill h. & noonan m. 2018. juvenile belugas (delphinapterus leucas) exhibit sex-specific social affiliations. aquatic mammals 44, 500–505, doi: 10.1578/am.44.5.2018.500. mcguire t.l., himes boor g.k., mcclung j.r., stephens a.d., garner c., shelden k.e. & wright, b. 2020. distribution and habitat use by endangered cook inlet beluga whales: patterns observed during a photo‐identification study, 2005–2017. aquatic conservation: marine and freshwater ecosystems 30, 2402–2427, doi: 10.1002/aqc.3378. michaud r. 2005. sociality and ecology of the odontocetes. in k. ruckstuhl & p. neuhaus (eds.): sexual segregation in vertebrates: ecology of the two sexes. pp. 303–326. cambridge: cambridge university. murayama t., suzuki r., kondo y., koshikawa m., katsumata h. & arai k. 2017. spontaneous establishing of cross-modal stimulus equivalence in a beluga whale. scientific reports 7, article no. 9914, doi: 10.1038/s41598-017-09925-4. mymrin n.i., communities of novoe chaplino, sireniki, uelen, and yanrakinnot & huntington h.p. 1999. traditional knowledge of the ecology of beluga whales (delphinapterus leucas) in the northern bering sea, chukotka, russia. arctic 52, 62–70, doi: 10.14430/arctic910. o’corry-crowe g., suydam r., quakenbush l., smith t.g., lydersen c., kovacs k.m., orr j., harwood l., litovka d. & ferrer t. 2020. group structure and kinship in beluga whale societies. scientific reports 10, article no. 11462, doi: 10.1038/s41598-020-67314-w. o’corry-crowe g.m., suydam r.s., rosenberg a., frost k.j. & dizon a.e. 1997. phylogeography, population structure and dispersal patterns of the beluga whale delphinapterus leucas in the western nearctic revealed by mitochondrial dna. molecular ecology 6, 955–970, doi: 10.1046/j.1365-294x.1997.00267.x. paulos r.d., trone m. & kuczaj s.a. ii. 2010. play in wild and captive cetaceans. international journal of comparative psychology 23, 701–722. recchia c.a. 1994. social behaviour of captive belugas, delphinapterus leucas. phd thesis, woods hole oceanographic institution. richard j., romano t. & sartini b. 2021. minimally invasive physiological correlates of social behaviour in belugas (delphinapterus leucas) under human care. polar research 40, article no. 5504, doi: 10.33265/polar.v40.5504. richard p.r., heide-jørgensen m.p., orr j.r., dietz r. & smith t.g. 2001. summer and autumn movements and habitat use by belugas in the canadian high arctic and adjacent areas. arctic 54, 207–222, doi: 10.14430/arctic782. robeck t.r., monfort s.l., calle p.p., dunn j.l., jensen e., boehm j.r., young s. & clark s.t. 2005. reproduction, growth and development in captive beluga (delphinapterus leucas). zoo biology 24, 29–49, doi: 10.1002/zoo.20037. sargeant b.l. & mann j. 2009. developmental evidence for foraging traditions in wild bottlenose dolphins. animal behaviour 78, 715–721, doi: 10.1016/j.anbehav.2009.05.037. sergeant d.e. 1973. biology of white whales (delphinapterus leucas) in western hudson bay. journal of the fisheries board of canada 30, 1065–1090, doi: 10.1139/f73-178. shelden k.e., robeck t.r., goertz c.e., mcguire t.l., burek-huntington k.a., vos d.j. & mahoney b.a. 2019. breeding and calving seasonality in the endangered cook inlet beluga whale population: application of captive fetal growth curves to fetuses and newborns in the wild. marine mammal science 36, 700–708, doi: 10.1111/mms.12653. siniscalchi m., dimatteo s., pepe a.m., sasso r. & quaranta a. 2012. visual lateralization in wild striped dolphins (stenella coeruleoalba) in response to stimuli with different degrees of familiarity. plos one 7, e30001, doi: 10.1371/journal.pone.0030001. skrzypczak n. 2016. personality traits in the atlantic spotted dolphin (stenella frontalis): syndromes and predictors of neophilia. msc thesis, florida atlantic university. smith b.r. & blumstein d.t. 2008. fitness consequences of personality: a meta-analysis. behavioral ecology 19, 448–455, doi: 10.1093/beheco/arm144. tamaki n., morisaka t. & taki m. 2006. does body contact contribute towards repairing relationships? the association between flipper-rubbing and aggressive behavior in captive bottlenose dolphins. behavioural processes 73, 209–215, doi: 10.1016/j.beproc.2006.05.010. themelin m., ribic c.a., melillo-sweeting k. & dudzinski k.m. 2020. a new approach to the study of relationship quality in dolphins: framework and preliminary results. behavioural processes 181, article no. 104260, doi: 10.1016/j.beproc.2020.104260. tsukasa m., fujii y., hashimoto t., shimoda a., iijima s., hayasaka k. shiroma n., koshikawa m., katsumata h., soichi m. & arai k. 2012. preliminary study of object labeling using sound production in a beluga. international journal of comparative psychology 25, 195–207. vasey p.l. 1995. homosexual behavior in primates: a review of evidence and theory. international journal of primatology 16, 173–204, doi: 10.1007/bf02735477. vergara v. & barrett-lennard l.g. 2008. vocal development in a beluga calf (delphinapterus leucas). aquatic mammals 34, 123–143, doi: 10.1578/am.34.1.2008.123. vergara v., michaud r. & barrett-lennard l. 2010. what can captive whales tell us about their wild counterparts? identification, usage, and ontogeny of contact calls in belugas (delphinapterus leucas). international journal of comparative psychology 23, 278–309. vergara v. & mikus m.a. 2019. contact call diversity in natural beluga entrapments in an arctic estuary: preliminary evidence of vocal signatures in wild belugas. marine mammal science 35, 434–465, doi: 10.1111/mms.12538. yeater d., guarino s., lacy s., dees t. & hill h. 2017. do belugas (delphinapterus leucas), bottlenose dolphins (tursiops truncatus), & pacific white-sided dolphins (lagenorhynchus obliquidens) display lateralized eye preference when presented with familiar or novel objects? international journal of comparative psychology 30, article no. 35458, doi: 10.46867/ijcp.2017.30.00.02. yeater d., hill h., baus n., farnell h. & kuczaj s. 2014. visual laterality in belugas (delphinapterus leucas) and pacific white-sided dolphins (lagenorhynchus obliquidens) when viewing familiar and unfamiliar humans. animal cognition 17, 1245–1259, doi: 10.1007/s10071-014-0756-x. preface20(2).indd 125orheim & goldman 2001: polar research 20(2), 125–126 preface in 1948, harald ulrik sverdrup left his position as director of the scripps institution of oceanography in la jolla, california, to become the first director of the norwegian polar institute. the npi was a renamed continuation of what until then had been an arctic-focused institute with a strong emphasis on topographical and geological mapping. together with a new director, the institute got a broadened scientific scope, especially in geophysics, and its purview became bi-polar. the early part of sverdrup’s illustrious career included being the chief scientist on amundsen’s maud expedition through the north-east passage, which was completed in september 1925, 75 years ago. the fram museum and the norwegian polar institute decided to collaborate on celebrating the expedition’s anniversary, and felt an international symposium in sverdrup’s honour was appropriate. the theme of the symposium was the role of the ocean–sea ice–atmospheric interaction in polar and sub-polar climate. we believe this theme would have been very much at sverdrup’s heart. although his main publications were in physical oceanography, he had worked with ahlmann on air–ice interaction on spitsbergen, and studied ice–ocean interaction both in the arctic and the antarctic. and he surely would have wanted to contribute to the current discussions of the role of the oceans in climate change. why is the symposium theme important? predicting future climate change is one of the major challenges for human society at present. to model with confidence effects of changes in greenhouse gases requires models that can reproduce known past climate changes. although much is still unknown, evidence suggests that natural surface temperature changes have at times occurred as rapidly as 1 °c per decade, lasting for several decades. such rapid climate changes may reflect changes in ocean circulation. predicting future changes demands an intimate understanding of oceanic, sea ice and atmospheric processes, and their interactions. h. u. sverdrup in his office at norwegian polar institute headquarters at 1 observatoriegata, oslo, in 1956. (npi picture library.) 126 preface as a result of the advection of heat by the north atlantic current (part of the gulf stream), north-western europe is 5 10 °c warmer than its latitude would indicate. the ocean circulation is partly driven by density differences, the so-called thermohaline circulation. coupled atmosphere–ocean models suggest that greenhouse warming may lead to dramatic weakening of the atlantic thermohaline circulation. within the venue of the symposium a workshop was therefore arranged to move forward an international effort to investigate whether changes in the north atlantic current and potentially a rapid climate cooling of north-west europe could occur in response to changes in the circulation of the arctic and subarctic seas. this asof (arctic/subarctic ocean fluxes) programme addresses the role of high latitude oceans in decadal climate variability and how to achieve flux measurements across the main gateways to and from the arctic ocean. see http://asof.npolar.no/about.html for more information about the programme. the symposium was arranged at relatively short notice. even so it attracted 70 participants from 10 countries. thirty-eight papers and posters were presented, 15 of which were subsequently submitted to polar research. the symposium, which took place from 21 to 24 september 2000 at the polar environmental centre in tromsø, was preceded by a reception at the fram museum in bygdøy, oslo. high points of the reception were addresses by the (then) norwegian minister of the environment siri bjerke and professor walter munk. these two pieces open this issue. while former minister bjerke’s speech adopts a political perspective on climate change in the north, professor munk—one of sverdrup’s early students—offers uniquely personal glimpses into harald ulrik sverdrup’s life. a paper by e. p. jones then presents an overview of some of the central ideas and questions about arctic ocean circulation. most of the remaining 13 articles tackle more particular aspects of the facet of the symposium’s theme concerning north atlantic and arctic ocean circulation. the editor would like to thank leif anderson, bob dickson, peter haugan, peter jones, jens meincke and others who helped enormously by suggesting potential reviewers. we are especially grateful to the referees themselves. though by no means problem-free, peer-review is the best method we have for controlling the quality of scientific publications. repeating a measure first taken in the last pages of the 1999 volume of polar research, this issue concludes with a list of the scientists who have served as referees for the journal in the last two years. dr. olav orheim director, norwegian polar institute dr. helle v. goldman editor, polar research bookreviews25(2).indd 181polar research 25(2), 181–188 widely read and acknowledged. however, the fi rst and last chapters are also an interesting read and give a nice basis for evaluating the biological and ethnographic material presented in the volume’s middle section, although now and again they are redundant. the book contains an interesting and eclectic collection of black and white illustrations including portraits, historical photographs, and technical and biological drawings. otto fabricius was a cleric, philologist, naturalist and ethnographer. much of his scholarly work stems from the relatively short period of his life spent as a missionary in greenland (1768–1773). his observations during these fi ve years and the experiences he had with greenlandic people clearly left a great impression on fabricius that lasted until his death. unlike many missionaries of his time, fabricius left the european colonytown where he was posted and lived in a greenlandic inuit community. he resided in a house built of stones, turf and timbers and learned the language and the ways of the people. much of their hunting culture revolved around knowing the habits of seals, and hence the people were a wealth of knowledge to fabricius in his faunal and ethnological studies. fabricius is undoubtedly best known for his publication fauna groenlandica (1780), but the work translated by kapel in this book, published a decade later (1790–91), allowed fabricius to expand greatly on the seal material presented in the earlier book. fabricius’s detailed description of the seals of greenland focuses fi rst and foremost on the harp seal or greenland seal (phoca groenlandica), describing: nomenclature; appearance and morphology; distribution (occurrence); behaviour; variation in occurrence and movements; breeding; feeding; predators; hunting methods; utilizabook reviews review of otto fabricius and the seals of greenland. meddelelser om grønland: bioscience 55, by finn o. kapel (2005). copenhagen: danish polar center. 150 pp. isbn 87-90369-77-7. kit m. kovacs norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, kovacs@npolar.no. in this three part volume finn kapel presents us with 1) a brief biography of fabricius, 2) a translation of his treatise on the seals of greenland and, fi nally, 3) a refl ection on the contribution of fabricius as a seal naturalist/scientist. i concur with dr kapel’s belief that the key paper is the second one. this work on greenland’s pinnipeds has until now been available only in danish and german and certainly deserves to be more skull of the “hook-snouted seal”, now known as the grey seal (halichoerus grypus). the drawing illustrated fabricius’s detailed description of the seals of greenland (1791). (reproduced with permission of the danish polar center.) portrait of otto fabricius. (reproduced with permission of the danish polar center.) 182 book reviews tion; parasites; and synonyms. ringed seals (pusa hispida), harbour seals (phoca vitulina), hooded seals (cystophora cristata) and bearded seals (erignathus barbatus) are presented similarly, although more briefl y. fabricius also gives short synopses of four additional “species” reported to him by the greenlanders. three of these animals are either mythical beasts or some sort of biological oddity such as albino specimens. the fourth species summary is the fi rst scientifi c account of the grey seal (halichoerus grypus), which fabricius describes primarily from material in his possession from an island off the danish coast. given the era in which fabricius was writing, his restricted time in greenland, and limited travel in the north, his biological accounts are remarkably insightful. occasionally, they are defi nitively incorrect, such as when he says, “as for the breeding of the harp seal, the matingtime is beyond all doubt in august” when in reality harp seals mate in march. but fabricius can be forgiven for using the size of the embryo in september to back-calculate the time of mating: delayed implantation was unknown in the 1700s. other small slips can be similarly accounted for. he is probably not credited as often as his work warrants; perhaps this book by finn kapel will help correct this situation. if allen’s history of north american pinnipeds (1880) or similar books are on your shelf, otto fabricius and the seals of greenland undoubtedly also deserves a place there. references allen, j. a. 1880: history of north american pinnipeds. a monograph of walruses, sea-lions, sea-bears and seals of north america. washington, d. c.: u.s. geological and geographical survey of the territories. fabricius, o. 1780: fauna groenlandica. (fauna of greenland.) copenhagen(?): j. g. rothe, hafniae & lipsiae. fabricius, o. 1790–91: udførlig beskrivelse over de grønlandske sæle, første og andet stykke. (detailed description of the seals of greenland, parts one and two.) copenhagen: skrivter af naturhistorie-selskabet. review of le monde polaire, mutations et transitions, under the direction of mariefrançoise andré (2005). paris: ellipses– carrefours. 187 pp. isbn 2-7298-2683-1. in french. bernard lefauconnier place du mollard, f-38700 le sappey en chartreuse, france, b.lefauconnier@wanadoo.fr. as mentioned on its back cover, le monde polaire, mutations et transitions comprises part of a collection (carrefours) intended for students of geography, history and the social sciences as well as for a wider public interested in understanding the changes our world is undergoing. other volumes in the series concern, for example, water in the arab world, large cities of north america and international commerce. twelve authors have collaborated on the book. the work is divided into two parts, made up in total of 11 chapters and six brief inset texts. the fi rst part is supposed to present some general aspects of the subject, regional aspects being introduced in the second part. seven of the book’s 11 chapters concern the indigenous peoples of the circumpolar region and constitute the heart of the volume. chapter 3 explores how the inuit conceive of—and are integrated with—their environment. chapter 4 discusses the transition from a subsistence economy to the present situation in the canadian arctic, focussing on nunavik, northern québec. major social transformations are described in chapter 10, with examples from the central canadian arctic. chapter 5 describes the emergence of the sense of an inuit identity, the creation of the inuit circumpolar conference and the building of inuit managerial and administrative competence, especially in the nunavut and nunavik territories, northern canada. chapter 7 concerns the transformation of greenlandic society. the situation of the saami, the subject of chapter 8, is unusual in that this population is represented in four countries: norway, sweden, finland and russia. the relationship between the saami and the norwegian state is described. the small-numbered indigenous ethnic groups—mainly reindeer herders—of the russian arctic are briefl y presented in chapter 9. only two chapters are devoted chiefl y to the 183polar research 25(2), 181–188 physical environment: chapter 1 presents a review of some recent research on the melting of glaciers and the related sea level rise while chapter 2 discusses the impacts of climate change through the metamorphosis of polar landscapes. one chapter (6) describes the development of polar tourism and chapter 11 summarizes past and present scientifi c activities in the antarctic. the limited space allotted to the environment in this book is regrettable. impacts related to climate change are not confi ned to glaciers and landscapes. in a book with academic intentions, references to the arctic climate impact assessment and the arctic monitoring and assessment programme would have been minimally necessary. in chapter 1, one of only two chapters devoted to the environment, some of the research results that are discussed are erroneously interpreted. for example, arendt et al. (2002) estimated the contribution to sea level of alaskan glaciers from the mid-1950s to the mid-1990s to be 0.14 ± 0.04 mm per year. this is equivalent to 5.6 ± 1.6 mm over the period, not 5 cm. another example is where the chapter’s author (incidentally, also the book’s editor), referring to rignot et al. (2003), writes that patagonian glaciers contribute even more than alaskan glaciers to sea level rise. in fact, rignot et al. said that the contribution from the patagonian glaciers is larger than that of alaskan glaciers per unit area. this is an important distinction. finally, the chapter mentions glacier surging but this phenomenon is evidently not understood by the author. there are other fl aws. chapter 6 takes into account the local and regional environmental impacts of tourism but does not mention the contribution to global pollution generated by the transportation of voyagers from low latitudes to the polar areas. in two places—a short inset in chapter 10 and a section heading in chapter 4— the use of the phrase “welfare state” (état providence) seems inappropriate. the texts discuss social and economic transformations and largescale interventions by the canadian central power. the “welfare state” must have been developed to try to counter-balance negative social effects of these transformations and is not in itself the cause of these negative effects. this is a strange book. the title claims to embrace the polar world but only a single chapter concerns the antarctic. the chapters discussing the environment merely skim lightly over a narrow slice of this important topic, without any real look at current climatic changes or the fact that the arctic and antarctic have already been affected by pollution, including ecotoxins, coming from sources elsewhere in the world. even with these drawbacks le monde polaire has value: there are few books presenting a broad picture of circum-arctic peoples. social, economic and geopolitical problems and the similarities and differences in the relationships between far northern indigenous peoples and the modern states that encompass them are briefl y but, in general, clearly described. i was particularly captivated by the subject of chapter 3—“corps inuit, espace géographique et cosmologique”, which opened for me, as an occidental scientist, a new window on the arctic and enriched my vision of it. references arendt, a. a., elchemeyer, k. a., harrison, w. d., lingle, c. s. & valentine, v. b. 2002: rapid wastage of alaska glaciers and their contribution to rising sea level. sciences 297, 382–386. rignot, e., rivera, a. & cassasa, g. 2003: contribution of the patagonia ice-fi elds of south america to sea level rise. science 302, 434–437 review of the north pole, by kathan brown (2004). san francisco, ca: crown point press. 504 pp (xi-xvi). isbn 1891300-18-0. thor b. arlov research and innovation unit, norwegian university of science and technology, no-7491 trondheim, norway, thor.arlov@ntnu.no. at fi rst glance a medium brick sized book entitled the north pole seems a promising read to anyone interested in the arctic, such as this reviewer. unfortunately it does not quite deliver according to expectations, presuming you expect solid information about the polar region. if, however, you are particularly interested in the personal experiences of arctic tourists with a dash of environmental concern, this book may not be a complete waste of time. the author kathan brown is the founder and 184 book reviews director of a renowned san francisco-based fi ne art printing press and publishing house. she has previously published various books on art and artists. however, her professional or personal connection with the polar regions are, as it were, shrouded in northern mists. the introduction to the north pole is not very helpful about her motives for writing this book. it appears she took part in a trip to the north pole sponsored by the american museum of natural history aboard the russian nuclear powered icebreaker yamal in 2002. the following year, she spent a week on a coastal cruise around svalbard. her experiences during these two trips have obviously inspired the book. in addition she has read a number of works about various arctic subjects and talked to some knowledgeable people, but to call this a thoroughly researched book would be stretching it. admittedly, brown seems to have no pretences in this direction. the north pole is voluminous in pages—a little more than half a thousand. the genre is a bit diffi cult to decide as the author mixes forms. since the voyage seems to be the structuring element, i suppose the book might be placed in the travel literature category. following a brief introduction that attempts to explain the somewhat odd composition of the book, there are eight main chapters. the fi rst seven are devoted to the north pole trip on the yamal. each of them is divided into three sections: a personal narrative by the author; excerpts from the journal of fridtjof nansen from the fram expedition; and a conversation with various people rendered in verbatim form. the last chapter is on the visit to svalbard and also contains a conversation, but— quite understandably—no excerpts from nansen. in between there are more than 100 photographs, the vast majority taken by the author herself. to the extent that there are any main themes at all, the issue of climate change and the question who was the fi rst on the north pole (if indeed peary cheated) recur frequently with slight variations throughout the book. if i were to be very polite i would call this unusual lay-out interesting, but to be honest i am rather put off by what seems to be a lack of serious effort making this book. the author’s own, original contribution represents the lesser part of the manuscript. the “journey” sections written by brown make up some seventy pages, or less than 15 % of the book. the photographs, also the work of brown, constitute nearly a quarter of the book. of the remaining 60 %, the excerpts from the journal of nansen fi ll almost 100 pages. the conversations or interview sections, where brown acts as “moderator”, occupy over 150 pages. at the end of the book there is a rudimentary time line, a short bibliography and a decent index. the only map in the book is a poor sketch of the arctic. although neatly organized, this book is in effect a compilation of somewhat disparate elements. by themselves the journey sections work fairly well; brown is a good observer and masters the style of a well-read journalist. she makes a pretty good job of popularizing science. this is the kind of prose one might expect to fi nd in for example national geographic: a personal account supplemented by factual information, or vice versa. the conversation sections function less well. their consistently verbatim form leaves the question open whether editing has taken place or not. anyway, stronger editing would have been desirable—considerable parts of the conversations are just plain small talk between fellow travellers. i kept wondering why the reader is invited to listen in. some of the contributors have more to offer, but the knowledge and capacity of participants like, for instance, arctic climate impact assessment director gunther weller and scott polar research institute archivist bob headland, could have been exploited far better in more elaborate interviews. in general, brown does not seem to distinguish between the substantial and the trivial in her role as moderator. for example, rendering an exchange of opinions concerning rock bands or suvs leaves me, in this context, cold. a more selective approach would certainly not have been amiss. nansen’s journal of his and hjalmar johansen’s dramatic attempt to reach the north pole from fram and their subsequent wintering on franz josef land in 1895–96 is a classic in arctic literature, but should rather be read in the original and in extenso. brown’s excerpts seem out of context and do not lend her account authority—just extra pages. i feel the use of nansen borders on literary theft when the author does not even make the effort of paraphrasing or commenting. finally, the photographs are for the most part unimpressive and appear to be ordinary amateur snapshots. considering the author’s professional background the reproduction is disappointing; the colours seem washed out and the subjects are fre185polar research 25(2), 181–188 quently unsharp. variations on ice fl oes are only interesting to a certain point, which brown oversteps. it does not make things better that there are no captions to the pictures, leaving the reader to guess when, where and why they were taken. in all fairness, kathan brown’s the north pole is probably not intended for well-read polar enthusiasts. it is indeed hard to imagine that readers of polar research will fi nd very much of interest in this book. it is simply too superfi cial with regard the factual parts and has too little to offer in literary terms. in my opinion, neither the gracious contributions of some prominent savants of the arctic nor the extensive quoting of nansen’s diary help salvage this north pole voyage from wreckage. at the uttermost ends of the earth: the physiology of polar fi shes, edited by anthony p. farrell & john f. steffensen (2005). amsterdam: elsevier. 396 pp. isbn 0-12350446-5. andrew clarke biological sciences, british antarctic survey, high cross, madingley road, cb3 oet cambridge, uk, accl@bas.ac.uk. ecologists and physiologists have always been interested in organisms living in extreme environments because of the light they shed on fundamental problems, and the general public has long been fascinated by animals living in climates so inhospitable that unprotected humans would rapidly perish. the pioneering physiologists of the early 20th century had quickly recognized that teleost fi shes with their dilute blood would have real problems in the cold waters of the polar regions, and when johan ruud collected the fi rst scientifi c specimens of an icefi sh he was able to confi rm that there really did exist a group of polar fi shes with no blood pigment. the scene was thereby set for an exploration of the physiology of polar fi shes, and this remains a vibrant fi eld of research to this day. the latest volume of the prestigious fish physiology series brings together a group of distinguished workers in the area of polar fi sh and provides a state-of-the-art survey of our understanding of the physiology of a group of organisms that have successfully adapted to one of the most physiologically challenging marine environments on the earth. the opening chapter (devries & steffensen) provides a brief overview of the marine environment of the polar regions, emphasizing the marked differences between the arctic and antarctic as much as their similarities, and thereby defi ning an important theme for the rest of the book. as well as differences in topography, bathymetry, riverine input and oceanography, attention is drawn to the very different tectonic, climatic, glacial and evolutionary histories of the two polar regions. the latter are fundamental to understanding the very different fi sh faunas of the arctic and antarctic, which are described in exemplary fashion in the second chapter by møller, nielsen & anderson. it is refreshing to see due attention being paid to the systematic and biogeographic aspects of the fauna in a volume devoted primarily to physiology, for this is essential to any complete understanding of evolutionary aspects of the physiology. the systematic treatment also covers all depths, thereby providing a broad context for the traditional (but not universal) concentration by physiologists on the more easily sampled shallow waters. the physiological chapters start with a thorough review of current knowledge of the metabolic biochemistry of polar fi shes by pörtner, lucassen & storch. the main themes of this chapter are the central role played by oxygen in shaping both thermal limits and lifestyle, and the trade-offs inherent in the utilization of energy in a strongly resource-limited environment such as the polar seas. the strengths of this chapter are the way physiological processes are set in an environmental context, the use of a wide range of model organisms, and the links between physiology and ecology. antifreeze proteins and freezing avoidance are reviewed by devries & cheng. the physiological challenge to teleost fi sh living in polar regions was recognized in the 1960s: even with an elevated blood salt concentration, polar fi sh are under cooled by almost 1k. whilst this may seem a small interval, because polar oceans contain ice crystals freezing of these fi sh would be inevitable in the absence of a protective mechanism. the existence of antifreeze glycoproteins and proteins in polar fi sh was quickly established by elegant work by art devries himself, but almost four decades later we are still unravelling the complexities of this system. in addition 186 book reviews to providing a masterly summary of the classical work, the authors also discuss areas of active current research making this the best current review of freezing avoidance in polar fi sh. in the next chapter steffensen concentrates on the respiratory system and metabolic rate; this chapter is thus closely allied to the earlier one by pörtner and colleagues but takes a quite different perspective by concentrating on the organismal rather than the molecular level. steffensen revisits the arguments over the existence of metabolic cold adaptation (mca) in polar fi shes, and does so in a thorough and balanced manner. once a fi sh has taken up oxygen, it then needs to move this oxygen around the body and the circulatory system is described by axelsson. a major factor here is the increase in blood viscosity at low temperature, and it is likely that selection for reduced circulatory costs coupled with the increased solubility of oxygen at low temperatures is what drove the evolution of reduced hematocrit in many polar fi shes and the complete loss of haemoglobin in one group, the icefi sh family channichthyidae. a key feature of this chapter is the discussion of the control of heart rate, setting the antarctic notothenioids in the wider context of non-polar fi sh. wells covers blood gas transport and haemoglobin, principally from studies of notothenioids but also setting the results in a wider context. wells also revisits the topic of mca, coming to a less defi nitive conclusion than steffensen. davison describes the skeletal musculature and locomotion, again principally based on studies of notothenioids. data are compared with warmer water fi sh and the differences related to ecological factors such as growth rate and buoyancy. in exploring the various ways in which temperature may limit muscle performance in polar fi sh, davison also discusses the limitation of mitochondrial atp supply, which links this chapter nicely to that by pörtner and colleagues. the fi nal chapter in the book is an authoritative review of the nervous system of polar fi shes by macdonald & montgomery. how does this volume rate overall? i believe it succeeds in providing a thorough, timely and authoritative survey of the physiology of polar fi shes. it will fi nd a place in my library and i have already found myself making extensive use of it. it is a pity that not every author has taken the opportunity to cover both arctic and antarctic studies, for the book does tend to concentrate on studies of notothenioids in many places. important and interesting as these fi sh are, they are confi ned to the southern hemisphere and physiologists have much to learn from thorough comparative studies. nevertheless this is an excellent summary of current knowledge and will remain for some time the place to go to learn about the physiology of fi shes living at high latitudes. review of the north pole was here: puzzles and perils at the top of the world, by andrew c. revkin (2006). boston: kingfi sher. 128 pp. isbn 0-7534-5993-0. helle v. goldman norwegian polar institute, polar environmental centre, no-9296 tromsø, norway, goldman@ npolar.no. ever wondered what the men’s toilet at camp borneo, a temporary russian camp on the ice about 96 km from the north pole, consists of? in the north pole was here, andrew revkin reveals this—“a waist high igloo-style wall of ice blocks” (p. 16)—and other details of the fi eld conditions experienced by scientists who carry out research near the very top of the world. using revkin’s own visit to the north pole environmental observatory—a science camp set up every year on the ice about 48 km from the north pole—as a jumping off point, the book describes the arctic and our past and ongoing efforts to understand it. climate change is a major theme. other topics, like early exploration of the region and the earth’s shifting magnetism, are also covered. in an enchanting chapter called “the imagined pole”, revkin describes early notions of the far north. we learn, for example, that in ancient hindu / buddhist cosmology, the stars in the sky were tied by ropes of wind to the north star, which was positioned above a gigantic mountain that constituted the world’s centre. four landmasses, divided by great rivers, lay around that centre. three thousand years ago, greek historians supposed that there was a society of “hyperboreans”: “an immortal race of people who lived in happiness and warmth beyond the source of the north wind” (p. 28). (this is sure to raise 187polar research 25(2), 181–188 a smile from readers who, like me, reside north of the arctic circle.) as late as the 19th century some maintained that the earth was hollow, with large openings into the interior at the north and south poles. according to another tenacious and surprisingly recent theory, the north pole was topped by a huge iron cone, which was the source of the planet’s magnetism. the bulk of the north pole was here is set in the present. revkin focusses his account on the scientists who undertake polar research, how they do it and the diverse challenges they face. one chapter begins with this riveting opening: “six of the world’s leading experts at solving arctic riddles are on their knees on the sea ice thirty miles from the north pole, stumped by three broken bolts” (p. 89). the chapter goes on to relate how the bolts were replaced and the winch repaired, and how the equipment contributes to our knowledge of the ocean, atmosphere and climate in the arctic. the heroes of revkin’s book are polar scientists and the divers, technicians and others who work with them. in the harsh environment of the arctic, research teams must combine “the brainpower of scientists with the brute strength of furniture movers, the wile of small-town mechanics, the courage (or recklessness) of extreme athletes, and the willingness to carry a shotgun to ward off polar bears” (p. 92). without oversimplifying its subject matter, the north pole was here makes science accessible to the nonspecialist reader. the slim book is aimed particularly at young adults but will also appeal to their parents. the chapters are short, the type is large and the text is amply illustrated with photographs, diagrams, maps and other illustrations. excerpts from new york times stories relating to the arctic (about half by the author) are sprinkled throughout the book. an award-winning journalist, revkin has been reporting on environmental issues for the new york times for over a decade. some readers may recognize the author’s name from his recent coverage of the bush administration’s attempt to stifl e jim hansen, director of nasa’s goddard institute for space studies, after hansen publicly called for prompt reductions in greenhouse gas emissions. the north pole was here is well timed: 2007-08 is an international polar year, during which scientifi c resources around the world will be concentrated on the arctic and antarctic. its antecedents have taken place in 1882-83, 1932-33 and 1957-58. revkin traces the polar year project back to the inspiration of the austrian karl weyprecht. upon returning from an arctic expedition in 1874, the explorer and scientist was determined to persuade the scientifi c institutions of many nations that it was crucial to coordinate meteorological and geophysical research and to share the resulting data. weyprecht’s efforts bore fruit, though it was posthumous: he died the year before the fi rst polar year. fourteen stations ringing the arctic were established by 11 countries (norway, sweden, finland, austria, netherlands, france, germany, uk, russia, canada, us). revkin observes that the fi rst polar year marked a major change in the culture of science, which became more open, collaborative and self-critical. this book is written with the american reader in mind. for example, the arctic ocean near the north pole is described as “two miles deep— deep enough that ten empire state buildings could be stacked beneath us” (p. 11). that the book tilts decidedly toward a youthful american readership is appropriate. the american association for the advancement of science (1990) has made the point that most schoolchildren in the us are not science literate. it behooves the generation of americans about to come of age to develop a basic understanding of the causes, signs and potential impacts of climate change, as well as to improve their knowledge of other major environ188 book reviews mental problems confronting us, such as natural habitat destruction and loss of biodiversity. the scientists who are spotlighted in the north pole was here are perhaps among the fi rst people to discern the magnitude of human impacts on the natural world; our children may be among the fi rst to have to cope with these changes during their lifetimes. revkin entitled his book after a sign erected by a scientist at the north pole observatory. the joke plays on the fact that the ice supporting the temporary science camp is in constant motion. less amusing are computer simulations according to which the ice on the surface of the arctic ocean may be gone by the end of this century. as is well known in the scientifi c community, this would have radical consequences for the world. let us hope that the north pole was here— a lively paean to polar scientists—is the kind of book that engages young minds in the arctic and in science itself. reference american association for the advancement of science 1990: science for all americans. new york: oxford university press. accessed on the internet at www.project2061.org/ publications/sfaa/online/sfaatoc.htm. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <feff00550073006100720065002000710075006500730074006500200069006d0070006f007300740061007a0069006f006e00690020007000650072002000630072006500610072006500200064006f00630075006d0065006e00740069002000500044004600200063006f006e00200075006e00610020007200690073006f006c0075007a0069006f006e00650020006d0061006700670069006f00720065002000700065007200200075006e00610020007100750061006c0069007400e00020006400690020007000720065007300740061006d007000610020006d00690067006c0069006f00720065002e0020004900200064006f00630075006d0065006e00740069002000500044004600200070006f00730073006f006e006f0020006500730073006500720065002000610070006500720074006900200063006f006e0020004100630072006f00620061007400200065002000520065006100640065007200200035002e003000200065002000760065007200730069006f006e006900200073007500630063006500730073006900760065002e002000510075006500730074006500200069006d0070006f007300740061007a0069006f006e006900200072006900630068006900650064006f006e006f0020006c002700750073006f00200064006900200066006f006e007400200069006e0063006f00720070006f0072006100740069002e> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice doi:10.3402/polar.v35.25966 r e s e a r c h n o t e regurgitation of the koilin layer in chinstrap penguins (pygoscelis antarcticus) and its association with gastric parasites han-kyu kim, chang-yong choi, min-su jeong, hwa-yeon kang & woo-shin lee department of forest sciences, seoul national university, 1 gwanak-ro, gwanak-gu, seoul 151-921, republic of korea keywords cuticula gastris; host-parasite interaction; nematodes; parasitic load; regurgitation; stegophorus macronectes. correspondence chang-yong choi, department of forest sciences, seoul national university, 1 gwanak-ro, gwanak-gu, seoul 151-921, republic of korea. e-mail: subbuteo@ hanmail.net abstract the koilin membrane, formed by the secretions of the ventricular and pyloric glands, functions as a protective layer in the gizzards of most bird species. however, the ecological functions of koilin have never been studied in freeranging penguins. during the two austral summers from 2012 to 2014, we observed the regurgitated koilins of chinstrap penguins (pygoscelis antarcticus) at narębski point on king george island, south shetland islands, and we detected a significant difference in the daily accumulation of regurgitated koilins between the pre-hatching and post-hatching periods in the rookery. we also found 233 gastrointestinal parasites, all stegophorus macronectes (nematoda, acuariidae), from 26 out of 45 koilins freshly regurgitated by chinstrap penguins. we suggest that the regurgitation of koilins may benefit adult chinstrap penguins in the wild by reducing parasitic loads when they fast during incubation; it may also help decrease the risk of parasite transmission to chicks. our results present the first observations of regurgitated koilins among breeding chinstrap penguins. how koilin regurgitation functions in penguins requires further study. among the gentoo penguins (p. papua) co-occurring at the study site, we observed no regurgitated koilin layers. the koilin membrane, also known as the cuticula gastris (hofmann & pregl 1907; eglitis & knouff 1962), is the variably developed internal lining of a carbohydrate/ protein complex (probably a mucoprotein), not keratinous, secreted by the ventricular and pyloric glands in avian gizzards (akester 1986; baumel et al. 1993; bels 2006; svihus 2011). the layer protects the muscles of the gizzard from the degrading effects of gastric acids and mechanical actions of food particles (bels 2006). the koilin layer may be relatively soft in the poorly-muscled type of gizzards (baumel et al. 1993). in general, the koilin layer is replaced slowly as it wears by mechanical abrasion. mcatee (1917) suggested that the shedding of koilin layers may be observed in most species of birds. the shedding occurs as the layer gradually wears away in a few pieces or is detached from the stomach wall and digested (mcatee 1906, 1917). however, a few cases of regurgitating behaviours have been reported in some bird species such as american kestrels (falco sparverius; vyas et al. 2009), anhingas (anhinga anhinga; bartlett & bartlett 1899), common cuckoos (cuculus canrous; newton et al. 1896), common starlings (sturnus vulgaris; newton et al. 1896), hornbills (buceros sp.; flower 1869), little owls (athene noctua; newton et al. 1896), mistle thrushes (turdus viscivorous; newton et al. 1896) and neotropical cormorants (phalacrocorax brasilianus; bartlett & bartlett 1899). although the presence of this layer has been mostly reported from post-mortem studies in various species of wild birds, most studies of koilin have focused on their structure (akester 1986) or how abnormal koilins affect poultry health (webb & colvin 1964; ono et al. 2004; kaldhusdal et al. 2012). a recent report on chemical irritations causing regurgitation of koilin suggests that koilin layers may protect against chemical toxicity as well as providing mechanical protection (vyas et al. 2009). polar research 2016. # 2016 h.-k. kim et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 25966, http://dx.doi.org/10.3402/polar.v35.25966 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/25966 http://dx.doi.org/10.3402/polar.v35.25966 however, there is little information on the functions of koilin in wild birds and, to the best of our knowledge, no clear description of koilin regurgitation in penguins has been published. during our study to monitor the breeding performances of chinstrap (pygoscelis antarcticus) and gentoo penguins (p. papua) at narębski point during the austral summers of 2012/13 and 2013/14, we often observed koilin regurgitation in chinstrap penguins, but not in gentoo penguins, and their regurgitated koilins in and around the penguin rookery as well as along two major passages to the nearby shoreline. on the basis of these observations, we speculated that koilin regurgitation in chinstrap penguins could be related to the chick-rearing activity, which requires active foraging and delivery of foods. in this paper, we report our observations of the regurgitated koilins and associated parasites, and the temporal change of koilin regurgitation in chinstrap penguins. we discuss the possible benefits of koilin regurgitation for free-ranging chinstrap penguins. methods study area narębski point is on the south-east coast of barton peninsula, king george island, in the south shetland islands, antarctica. at the narębski point study site (628 14? 14.3ƒ s, 588 46? 27.1ƒ w), about 3000 pairs of chinstrap and 2300 pairs gentoo penguins breed every austral summer (republic of korea 2014). chinstrap penguin rookeries are located on rocky slopes close to the shore and are divided into several sub-groups (colonies) by huge pillars of rocks or cliffs. sample collection and analysis temporal change in koilin regurgitation among chinstrap penguins was assessed by daily counts in six plots for 15 days from 19 december 2013 to 6 january 2014. each plot (2.5 m �2.5 m) was set within the same chinstrap penguin colony (1475 nests) and had 7.390.5 breeding pairs of chinstrap penguins. koilin was removed from the plot before the daily counts at 18 december 2013. we searched daily for freshly regurgitated koilins in the plots, and removed all found koilins from the plots to avoid double counts. when a survey was interrupted by unfavourable weather conditions (20 and 30 december 2013), we also excluded the next day’s results for further analysis. we assessed the temporal change in the daily accumulation number of koilins through spearman correlation analysis, and compared the numbers before (pre-hatching period: 5 days) and after (post-hatching period: 10 days) the mean hatching date of the colony of chinstrap penguins (25 december 2013; kim, unpubl. data) using the mannwhitney rank-sum test. although snowy sheathbills (chionis albus) were occasionally observed to consume the koilin in the study area, we assumed that there was no temporal change in the effect of their scavenging activity. all statistical analyses in this study were conducted using sigmaplot version 12.0 (sysstat 2012). we collected the koilins on the ground in the chinstrap penguin’s rookery from 7 to 30 december 2013; only freshly regurgitated layers that were intact, cylindrically shaped, and not damaged by scavengers such as snowy sheathbills nor contaminated by faeces of nearby penguins were collected (fig. 1). at the laboratory at king sejong station on barton peninsula, the koilins were microscopically examined for gastrointestinal parasites (see vidal et al. 2012). the number of parasites in each koilin was recorded, and they were kept in cryovials filled with 70% ethyl alcohol for further identification. descriptive statistics, prevalence (proportion of koilins containing parasites) and the mean intensity (average number of parasites in each koilin containing parasites) with standard deviations, range and 95% confidence intervals (cis) were calculated using the clopper-pearson interval (for prevalence) and 2000 bootstrap replications (for mean intensity) with qp 3.0 software (rozsa et al. 2000; reiczigel et al. 2013). the collected parasites, which were all nematodes, were identified later under microscopes at the laboratory at seoul national university in the republic of korea. identifications were based on taxonomic keys and morphological descriptions, in particular regarding the structure of their cephalic collars, following mawson (1953), zdzitowiecki & drózdz (1980) and vidal et al. (2016). fig. 1 a koilin layer regurgitated by an adult chinstrap penguin (pygoscelis antarcticus), 21 january 2014. koilin regurgitation in chinstrap penguins h.-k. kim et al. 2 (page number not for citation purpose) citation: polar research 2016, 35, 25966, http://dx.doi.org/10.3402/polar.v35.25966 http://www.polarresearch.net/index.php/polar/article/view/25966 http://dx.doi.org/10.3402/polar.v35.25966 results the daily accumulation of regurgitated koilins, which are yellow with a green tip (fig. 1), per plot showed the temporal decline along the breeding season (spearman’s rank-order correlation; rs� �0.795, pb0.001). the number was higher in the pre-hatch period (mean and sd: 3.090.3, median: 3.0, range: 0�8, n�30) than that in the post-hatching period (mean and sd: 0.790.1, median: 0.0, range: 0�3, n�60) (mann-whitney u �181.0, df �1, pb0.001; fig. 2). a total of 45 intact and fresh koilin layers were collected in the rookery of chinstrap penguins during the survey. we also found 233 parasites, all identified as stegophorus macronectes (nematoda, acuariidae), in 26 out of 45 koilins. anchored in the regurgitated koilins, the parasitic nematodes were alive at the time of collection (range: 0�61, prevalence: 57.8%, 95% ci for prevalence: 42.2� 72.3%, mean intensity: 8.96, 95% ci for mean intensity: 5.96�16.70). discussion based on field observations in the austral summer of 2012/ 13, we confirmed that chinstrap penguins regurgitate yellow koilins, which were partially coloured green, possibly from regurgitated bile (bels 2006), mostly before the hatching dates. though the regurgitated koilins within the colony can be easily trampled by penguins or partially fed on by scavenging birds, the regurgitated koilins were still common in terms of distribution and quantity. the fresh koilins were cylindrically shaped when undamaged and untrampled, suggesting that free-ranging wild chinstrap penguins may replace the whole koilin layer at once during the early breeding season. considering the live parasites found in the regurgitated koilins, it may be better to regurgitate the koilin than to send it to the duodenum or further along in the intestines, to prevent pathogenic effects, such as ectopic infection. more regurgitated koilin layers were found in the prehatching period, compared to the post-hatching period, indicating that chinstrap penguins are more likely to regurgitate koilin layers when they are incubating eggs compared to when they are rearing chicks. because this layer protects the stomach wall from mechanical and chemical irritation, digestive activity is paused when this layer is regurgitated and gizzards of birds in this stage must be kept empty until the koilin is renewed (mcatee 1917; vyas et al. 2009). breeding parents of chinstrap penguins take turns sitting on the nest in a 5�10 day period during incubation (lishman 1985; borboroglu & boersma 2013), giving them time to empty their stomachs and replace koilin layers. in contrast, when chicks hatch, parental turn-taking occurs on a daily basis (borboroglu & boersma 2013). therefore, we suggest that breeding chinstrap penguins in the wild have a strategy of disposing of and renewing the whole koilin before hatching, because it cannot coincide with food delivery to chicks. the most important role of such regurgitation must be to replace the old lining in the ventriculus for renewed gizzard protection (bels 2006). however, as mcatee (1917) suggested, shedding koilins may help birds to reduce their parasitic load, particularly nematodes, which are usually anchored between the koilin layer and the gizzard wall. as chinstrap penguins are a marine predator that consume mainly antarctic krill (euphausia superba; ratcliffe & trathan 2012), their gizzards’ koilin layers may not be mechanically abraded in the way that they are in granivorous birds. these penguins’ gastrointestinal tracts may be under greater stress from parasites, acquired from the marine food web, than stress by mechanical abrasions. many parasitic stegophorus macronectes were observed in the regurgitated koilins in this study. this nematode was the only gastrointestinal parasite species found in the gizzard of chinstrap penguins in prior studies (barbosa & palacios 2009; vidal et al. 2012; brandao et al. 2014). the previously reported prevalence (67%) of s. macronectes in three adult chinstrap penguins on deception island, south shetland islands (vidal et al. 2012), falls into the range of the prevalence estimated from the koilin analysis in this study (42.2�72.3%). given the mean intensity of the nematode (39.5943.9) reported from the same species in the same region (vidal et al. 2012), getting rid of a koilin harbouring nine nematodes*the mean fig. 2 temporal change in the daily accumulation of regurgitated koilins at six plots in the breeding colony of chinstrap penguins. the size of filled circles represents the number of plots (ranging from one to six). h.-k. kim et al. koilin regurgitation in chinstrap penguins citation: polar research 2016, 35, 25966, http://dx.doi.org/10.3402/polar.v35.25966 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25966 http://dx.doi.org/10.3402/polar.v35.25966 intensity found in our samples*may result in a roughly 23% reduction in the gastrointestinal nematode load. however, because of the small sample size in the study by vidal et al. (2012), this quantitative comparison is not reliable and the effect of such removal on the body condition of its host is unclear. nonetheless, these findings are suggestive of the potential role of koilin regurgitation in reducing parasites. parental provisioning can transfer gastric parasites to chicks (muzaffar & jones 2004; vidal et al. 2012), and reducing gastric parasites in the parent’s gizzard may decrease the risk of transmission through food delivery. although the pathogenicity and the removal effects of s. macronectes in adult chinstrap penguins are not well understood, increased growth rates were observed in experimentally de-wormed chinstrap nestlings compared to their control siblings, which shows the negative effects of gastrointestinal parasites on nestling body conditions, survival rate and fitness in this species (palacios et al. 2012). therefore, we suggest that the koilin regurgitation by fasting adults of wild chinstrap penguins may benefit their chicks to an unknown extent. in contrast to chinstrap penguins, we never observed any regurgitated koilin layers among the gentoo penguins co-occurring at the study site. whether, and in what manner, gentoo penguins replace their koilin layers is unknown. to the best of our knowledge, this is the first study of koilin regurgitation in penguin species and the first report on the prevalence of parasites in regurgitated koilin layers. however, our knowledge is limited to this small study site and short time period. further observations as well as experimental studies across other penguin species in different areas and seasons are required to better understand the details concerning the mechanisms and functions of koilin regurgitation and replacement. acknowledgements we thank the korea polar research institute and king sejong station for their support on our field studies in antarctica. we thank especially to mr. jin-woo jeong for suggesting initial steps of this study. this study was funded by the ministry of environment, republic of korea, as part of a long-term ecosystem monitoring on the antarctic specially protected areas (aspa) no. 171 on king george island (pn13130). this study was performed with permissions (ilad-2692 [2013.10.18]) from the korean ministry of foreign affairs and trade, according to the act on antarctic activities and protection of antarctic environment. references akester a. 1986. structure of the glandular layer and koilin membrane in the gizzard of the adult domestic fowl (gallus gallus domesticus). journal of anatomy 147, 1�25. barbosa a. & palacios m.j. 2009. health of antarctic birds: a review of their parasites, pathogens and diseases. polar biology 32, 1095�1115. bartlett a.d. & bartlett e. 1899. wild animals in captivity, being an account of the habits, food, management and treatment of the beasts and birds at the ‘‘zoo.’’ london: chapman and hall. baumel j.j., king a.s., breazile j.e., evans h.e. & vanden berge j.c. 1993. handbook of avian anatomy: nomina anatomica avium. cambridge, ma: nuttall ornithological club. bels v.l. (ed.). 2006. feeding in domestic vertebrates: from structure to behaviour. wallingford: cabi publishing. borboroglu p.g. & boersma p.d. 2013. penguins: natural history and conservation. seattle: university of washington press. brandao m.l., moreira j. & luque j.l. 2014. checklist of platyhelminthes, acanthocephala, nematoda and arthropoda parasitizing penguins of the world. check list 10, 562�573. eglitis i. & knouff r. 1962. an histological and histochemical analysis of the inner lining and glandular epithelium of the chicken gizzard. american journal of anatomy 111, 49�65. flower w.h. 1869. note on a substance ejected from the stomach of a hornbill (buceros corrugatus). proceedings of the zoological society of london 1869, 150. hofmann k. & pregl r. 1907. uber koilin. (about koilin.) hoppe-seyler?s zeitschrift für physiologische chemie 52, 448�471. kaldhusdal m., hetland h. & gjevre a.g. 2012. non-soluble fibres and narasin reduce spontaneous gizzard erosion and ulceration in broiler chickens. avian pathology 41, 227�234. lishman g.s. 1985. the comparative breeding biology of adélie and chinstrap penguins pygoscelis adeliae and p. antarctica at signy island, south orkney islands. ibis 127, 84�99. mawson p.m. 1953. parasitic nematoda collected by the australian national antarctic research expedition: heard island and macquarie island, 1948�1951. parasitology 43, 291�297. mcatee w.l. 1906. the shedding of the stomach lining by birds. auk 23, 346. mcatee w.l. 1917. the shedding of the stomach lining by birds, particularly as exemplified by the anatidae. auk 34, 415�421. muzaffar s.b. & jones i.l. 2004. parasites and diseases of the auks (alcidae) of the world and their ecology*a review. marine ornithology 32, 121�146. newton a., gadow h., lydekker r., roy c.s. & shufeldt r.w. 1896. a dictionary of birds. london: adam and charles black. ono m., okuda y., shibata i., sato s. & okada k. 2004. pathogenicity by parenteral injection of fowl adenovirus isolated from gizzard erosion and resistance to reinfection in adenoviral gizzard erosion in chickens. veterinary pathology online 41, 483�489. koilin regurgitation in chinstrap penguins h.-k. kim et al. 4 (page number not for citation purpose) citation: polar research 2016, 35, 25966, http://dx.doi.org/10.3402/polar.v35.25966 http://www.polarresearch.net/index.php/polar/article/view/25966 http://dx.doi.org/10.3402/polar.v35.25966 palacios m., valera f. & barbosa a. 2012. experimental assessment of the effects of gastrointestinal parasites on offspring quality in chinstrap penguins (pygoscelis antarctica). parasitology 139, 819�824. ratcliffe n. & trathan p. 2012. a review of the diet and at-sea distribution of penguins breeding within the camlr convention area. ccamlr science 19, 75�114. reiczigel j., rozsa l., reiczigel a. & fabian i. 2013. quantitative parasitology. qpweb, version 1.0. accessed on the internet at http://www2.univet.hu/qpweb on 07 april 2014. republic of korea 2014. monitoring and management report of narębski point (aspa no. 171) during the past 5 years (2009�2014). background paper 7, revision 1. xxxvii antarctic treaty consultative meeting. 28 april�07 may 2014, brasilia. rozsa l., reiczigel j. & majoros g. 2000. quantifying parasites in samples of hosts. journal of parasitology 86, 228�232. svihus b. 2011. the gizzard: function, influence of diet structure and effects on nutrient. world’s poultry science journal 67, 207�224. sysstat. 2012. sigmaplot for windows, version 12.0. chicago: sysstat software. vidal v., ortiz j., diaz j.i., de ybañez m.r., amat m., palacios m., benzal j., valera f., de la cruz c. & motas m. 2012. gastrointestinal parasites in chinstrap penguins from deception island, south shetlands, antarctica. parasitology research 111, 723�727. vidal v., ortiz j., diaz j.i., zafrilla b., bonete m.j., ruiz de ybañez m.r., palacios m.j., benzal j., valera f., de la cruz c., motas m., bautista v., machordom a. & barbosa a. 2016. morphological, molecular and phylogenetic analyses of the spirurid nematode stegophorus macronectes (johnston & mawson, 1942). journal of helminthology 90, 214�222. vyas n.b., spann j.w. & hill e.f. 2009. acute oral toxicities of wildland fire control chemicals to birds. ecotoxicology and environmental safety 72, 862�865. webb t. & colvin j.r. 1964. the composition, structure, and mechanism of formation of the lining of the gizzard of the chicken. canadian journal of biochemistry 42, 59�70. zdzitowiecki k. & drózdz j. 1980. redescription of stegophorus macronectes (johnston et mawson, 1942) and description of stegophorus arctowskii sp. n. (nematoda, spirurida) from birds of south shetlands (the antarctic). acta parasitologica polonica 27, 205�212. h.-k. kim et al. koilin regurgitation in chinstrap penguins citation: polar research 2016, 35, 25966, http://dx.doi.org/10.3402/polar.v35.25966 5 (page number not for citation purpose) http://www2.univet.hu/qpweb http://www.polarresearch.net/index.php/polar/article/view/25966 http://dx.doi.org/10.3402/polar.v35.25966 breeding biology of dark-bellied brent geese branta b. bernicla in taimyr in 1990 in the absence of arctic foxes and under favourable weather conditions bernard spaans. martin stock, andrew st. joseph, hans-heiner bergmann and barwolt s. ebbinge spaans, b.. stock. m.. st.joseph. a . . bergmann. h.-h. & ebbinge, b. s. 1993: breeding biology of dark bellied brent geese branta b. bernicla in taimyr in iyyo in the absence of arctic foxes and under favourable weather conditions. polar research 12(2). 117-130. in combination with observations in spring staging and wintering grounds in western europe, a detailed etho-ecological study of nesting dark-bellied brcnt geese branta b. bernicla in western taimyr. krdsnoyarsk, russia. was made in 1990. most brent geese arrived on the breeding grounds from 14-19 june and started nesting within a few days. in the study area 264 nests of breeding brent geese were found, mainly on islands but also along small rivers on the mainland. the mean clutch size was 3.0 and 80% of the eggs hatched. time budget studies showed that incubating females spent on average 138 minutes per 24 hours on feeding. despite favourable wcathcr conditions and a low density of arctic foxes. only about one-third of the mature birds in the study area bred. i n the autumn an intermediate breeding success of 20% juveniles was recorded in the wintering areas. this was probably due to the relatively poor condition in which the brent geese left their spring staging areas. v p ~ ~ ~ ~ ~ t . i s t ' ' bernard spaans and barwolf s . ebbinge. lnsfitufe for forestry and nature research (ibn-dlo). p. 0. box 23, nl-6700 a a wageningen, the netherlands; martin stock, nationalparkamt. schleswig-holsteinkche wattenmeer. a m hafen 40 a. 0-2253 tonning, germany; andrew st. joseph, mellfarm. pallesbury. muldon. essex cm9 8ss. england; hans-heiner bergmann, fachbereich biologie der unioersitat osna briick. postfach 4469, 0-4500 osnabriick. germany. introduction the factors that determine the large variations in annual breeding success of the dark-bellied brent geese branta bernicla bernicla are the subject of an ongoing debate (summers & underhill 1987, 1990; ebbinge 1989, 1990). factors assumed to be the most important are weather conditions in the arctic breeding area (barry 1962; boyd 1987), size of lipid and protein reserves upon arrival there (ebbinge et al. 1982), and nest predation by arctic foxes aiopex lagopus (roselaar 1979; summers 1986; dhondt 1987; greenwood 1987; owen 1987; anthony et al. 1991). nutrient reserves are stored in the dutch, german and danish wadden sea in the 5-6 weeks prior to spring migration (ebbinge et al. 1982; st. joseph 1982). weather conditions during migration affect the final condition upon arrival (ebbinge 1989). the number of arctic foxes and their predation pressure on arctic birds have been hypothesized to depend mainly on the abundance of lemmings lemmus sibiricus and dicrostonyx torquatus. in particular in years after a lemming peak, the increased number of foxes are expected t o ter rorize the nests of arctic breeding birds due to scarcity of lemmings as their main prey. the discussion about the relative importance of each of these factors, however, is hampered by the lack of knowledge about what is really happening in the breeding area of brent geese. the opportunity provided by e. e. syroech kovskiy of the laboratory of evolutionary ani mal morphology and ecology of the russian academy of sciences to visit the taimyr peninsula in 1990 and t o start a detailed study on the breed ing biology of brent geese gives new dimensions to this discussion. this paper presents the results of our first tai myr expedition in 1990 and data on body con dition and reproductive success gathered in the wintering and spring staging areas in western europe before and after the same breeding season. these data from the wintering areas, which have been gathered over several years, can now be viewed in perspective with data from taimyr. 118 b . spaans et al. our study on the breeding biology of brent geese in taimyr focused on the following points: (1) the condition (body-mass) of the geese upon arrival; (2) the importance of body reserves dur ing the breeding season; (3) the effect of potential predation on behaviour and breeding success of the geese; (4) the effect of lemming density on predation; and finally (5) how these factors are affected by the weather conditions. we cannot presume to solve the riddle of the cyclic variations in annual breeding output of the brent goose on the basis of one season's work, but we feel that our first results can help to shape future work and therefore merit early consider ation. study area habitat the study was carried out in the coastal area north of the piassina delta, about 200 km ene of dickson, taimyr, ussr. the base camp was situated along the lidia bay, 74"07'n, 86"50'e (fig. 1). this location was chosen in advance because of the presence of a small archipelago with the promising name 'bird islands'. we stayed in the study area from 1 june until 28 july 1990. the coastal mainland consists of low, undu lating tundra traversed by a number of small rivers of which the lidia is the most important. the tundra vegetation is dominated by mosses, lichens, sedges and grasses. during snowmelt the rivers are wide, but after the snow disappears the water level declines and a lush vegetation of monocots develops on the banks alongside these rivers. this vegetation is dominated by dupontia psilosantha, carex aquatilis, arctophila fulua, eriophorum scheuchzeri and puccinellia s p p . similar vegetation also occurs on the flat outer beacon islands (fig. 1). in june the vegetation on these islands was dominated by mosses, but later in the season young monocots emerged. island 1 was rather flat with mainly tundra veg etation comparable to the mainland. islands 2, 3 and 4 were rocky with bare patches, some areas of tundra vegetation, and a richer grassy vegetation around colonies of the lesser black-backed gull larus fuscus taimyrensis (cramp & simmons 1983). the large island farwaternie was covered with tundra vegetation similar to that of the main land. fig. 1. upper: location of the study area in taimyr, russia. lower: the study area north of the piassina-delta in taimyr is indicated by grey. the bird islands arc numbered. weather conditions in 1990 daily minimum and maximum temperatures were measured at the base-camp. percentage snow cover was measured by counting the number of steps with and without snow along a 2200 metre long tundra transect from the seashore to the top of a hill, north of the lidia bay. temperature and snowmelt data from 1977 to 1990 collected by a station along the piassina-river, ca. 40 km southeast of our camp, were made available t o use by y. kokorev. comparison of the mean maximum temperature over the previous 14 years with the minimum and maximum temperatures measured at our camp (fig. 2) indicates that june and july 1990 were relatively warm. in our camp, the daily maximum temperature was on average breeding biology of dark-bellied brent geese 119 25 20 15 9 5 10 3 e e $ 5 0 -5 .lot.,, ,, ,, , ,, ,, , , , , ,, , , , , ,, , , ,, , , , , , , , , , i , , , , , , ,j 1 4 7 10 13 16 19 22 25 28 1 4 7 10 13 16 date in june and july 1990 fig. 4. duration of snow cover from 1977 to 1990. the number data from thc piassine weather-station ca. 41) km southeast of the study area. 2" higher than at the weather station. the progress of snowmelt north of the lidia bay is shown in fig. 3. in early july the area was almost snowfree. snowmelt-data over the previous 14 years show that 1990 was a year with early snowmelt (fig. 4). until 10 june it was possible to reach the bird islands from the mainland over the frozen bay. throughout the first week of july, islands 1 and 2 could still be reached after crossing a narrow channel by boat. from the second week of july, the islands were completely surrounded by water and could only be reached by boat. date in june and july 1990 fig. 3, percentage of mainland-tundra covered with snow from 4 june to 4 july. predators lemmings and arctic foxes. to establish the effect of predation on the behaviour and breeding success of the geese, counts were made of lemmings, arctic foxes and other potential pred ators. a population-dynamic study of lemmings was carried out by russian biologists. lemming density was measured by catching the animals both with live-traps and ordinary traps. during six weeks of continuous trapping with hundreds of traps less than twenty lemmings were caught, on average 0.25 lemmings/100 trap nights (ryhli kova, 1993). on about 750 man-days spent in the tundra by the participants of o u r camp during june and july, only a few lemmings were observed. snowy owls nyctea scandiaca, rough legged buzzards buteo lagopus and pomarine skuas stercorarius pomarinus, all lemming-pred ators, were seen migrating during the first half of june, but these predators disappeared almost completely from our study area, without making any attempt to breed. this is also an indication of a poor lemming year. not a single arctic fox was observed and local hunters had not even tried to catch foxes the preceding winter because there were so few. other potential predators. lesser black backed gulls were common breeding birds in our study area (over 1200 pairs). these gulls were already present on the bird islands when we 120 b. spaans et al. arrived on 1 june. glaucous gulls larus hyp erboreus were rare and only a few nests have been found. long-tailed and arctic skuas stercorarius longicaudus and s . parasiticus were also breeding in our study area but in small numbers. methods in western europe on the dutch island terschelling brent geese were caught with cannon nets on 14 and 16 may 1990 to determine their body-mass just before their departure for the arctic. migration dates were recorded by several field workers in the wadden sea area in the second half of may (from 1976 to 1990). in autumn 1990 we recorded juv enile percentage and family-size in many staging sites along the coasts of the north sea, to arrive at a reliable over-all population mean. in this way we accounted for the unequal distribution of families with juveniles over the wintering area (lambeck 1990a, 1990b). special attention was devoted to geese with engraved colour-rings to determine pair-bond and breeding success of birds marked in taimyr. in taimyr brent geese were caught with cannon nets in our study area from 15 t o 19 june 1990 to determine pre-breeding body-masses. we marked captured individuals with individually-coded colour rings, of which the inscriptions can be read by telescope at 300 m distance. we surveyed the entire study area for breeding geese; clutch-size and egg mass were determined in the first week of incubation. on seven different days we observed two breeding pairs on island 2 (called pair a and b) for 24 consecutive hours from a hide. on the mainland along the lidia river we watched, also from a hide, five incubating females (called numbers 1 to 5) and only 1 male (the male of female 3). this male was chosen because both members of pair 3 were individually recognizable (marked with colour-rings in the netherlands in may 1989). along the lidia river we observed on six days for 24 consecutive hours, but only male 3 was observed on one of these days. due to the fact that incubation of the lidia females started 5 days later than on the island, calendar days do not correspond when observations of both areas are plotted against the start of incubation. during these 24-hour periods, activity of the geese was noted every 5 minutes. we also recorded starting time and duration of feeding-recesses of the females, all interactions with potential predators, all intraspecific interactions and time and number of potential predators present near the nesting geese along the lidia river. in addition, a scan of the activities of a flock of non-breeders (birds without a nest or territory, living in flocks) along the lidia river was made every 15 minutes. non breeders did not occur on the bird islands. nests with a known number of eggs were observed during hatching to determine the frac tion of eggs that hatched. the size of each observed family was recorded immediately after hatching. post-hatching behaviour of brent goose families was recorded to establish the effect of predation of goslings by gulls and skuas. we also counted the non-breeding birds on the islands where they were moulting. results body condition during spring staging and breeding success as measured in autumn the breeding success measured in autumn flocks is plotted in fig. 5 against the mean body-mass of adult female brent geese (caught during spring staging just before departure to the north of siberia), together with comparable data from the other years (ebbinge 1989; ebbinge & spaans 1992). compared with other years, 1990 showed a relatively poor condition of the geese before departure and an intermediate breeding success of 20% juveniles in autumn. the mean number of juveniles per successful pair was 2.4 (n = 336). in 1990 the geese left the wadden sea early (fig. 6). wind conditions during migration in the north sea area and through the baltic region were favourable with 57% of days with a tailwind blowing in the period 21-30 may in the baltic (see ebbinge 1989 for sources and methods of calculation). arrival and condition on the breeding grounds we saw the first two brent geese on 10 june. most migrating geese were observed from 14-19 june (fig. 7). between 15 and 19 june, nine brent geese were caught, weighed and individually marked breeding biology of dark-bellied brent geese 121 fig. 5 . spring body-mass of female hrent geese just before departure i n the end of may from the wadden sea area and breeding succc~s. expressed as percentage of juveniles. in the subsequent autumn and winter. years that were unfdvourabk due to (head)wind during spring migration are given between brackets and unfavourablc years due to high inferred fox pre dation on the breeding grounds are circlcd (data from ebhinge 1989 and ebbinge & spaans 1992). (table 1). the mean weight of the females was only 40g less than the weight of the females caught in the wadden sea (fig. 5). although the sample is very small, the small difference in mean body-mass indicates that the costs of migration were (partly) compensated on staging grounds between the baltic region and taimyr. c l in in 2 v) u 0 m" c l q, a 3 c e periods in may and june fig. 6. timing of departure from the spring staging area. num ber of days with hrent goose mass departure from the dutch wadden sea in 5-day periods from 1976 to 1989. the arrow indicates the mass departure in 1990. fig. 7. arrival of brent geese in taimyr and timing of egg laying, incubation and hatching. the left graph indicates the number of migrating brent geese per day in the lidia bay area, the right graph indicates the number of incubating females on island 1. distribution of breeding brent geese over the study area a total of 264 nests of brent geese were found in the study area, 252 (= 96%) on the small off shore bird islands and 12 nests on the mainland alongside small rivers (fig. 8). the mean laying date of the first egg on a small colony along the lidia river on the mainland was about one week later than the two inner bird islands. we d o not have data on nest initiation on the outer islands. a review of the timing of migration, egg-laying, incubation and hatching is given in fig. 7. most of the geese started nesting within a few days after arrival. a sketch of the distribution of vegetation types on island 2 with the position of 16 brent goose nests is given in fig. 9. in contrast to the veg etation the nests seemed t o be rather evenly dis persed and the mean density was 2,8 nestslha. the highest density was measured on island 1: 3,9 nestslha. mean clutch-size was 3.0 2 1.2, (n = 72) and ranged from 1 to 6 eggs per nest. mean egg-weight was 79.5 2 7.5 g, (n = 94 eggs), range 64 to 98 g, fresh weight i.e. measured at clutch completion ( 2 standard deviation). we could not relocate any of the 11 individually marked geese caught in june as a breeding bird in our study area but they could have been missed. 122 b. spaans et al. table 1. pre-breeding body-mass of 9 brent geese caught between i5 and 19 june. the pair-bond and the net breeding succcss have been determined in the subsequent autumn and winter in western europe. codes male body-mass female body-mass observed in w. europe number of juv. rpga x.rpgc rpgk x rpgh rpgf rpgj rpgn rpgp rpgt mean body-mass 1510 1490 1380 1590 1484 1610 1380 1400 1560 1530 1496 breeding behauiour only the female incubated, leaving the nest regu larly to feed while the male stayed near the nest. around the nest, the males defended a territory. we were able to precisely estimate the length of the incubation period for one pair which was 24.5 days (measured from clutch completion to hatch of last gosling). the total time off the nest (recess time) per 24 hour period is plotted for the two island females and the five lidia females in fig. 10. when a female left the nest, she carefully covered the eggs with down, and frantically started to feed, usually within her territory, but sometimes on another island. on average, 90% of the time females spent off their nest was used for feeding. while the female was off, the male usually stayed close by to defend the nest against gulls or skuas. all females left their nests more often as the fig. 8. number of nesting brent geese in the study area. the black square indicates the location of the base-camp. island 2 was the main observation island. breeding season progressed, varying from once per 24 hours in the beginning to up to 16 times per 24 hours at the end (fig. 11). the average recess frequency was 11 per day for the lidia females and 9 per day for the island females. although there was some variation in the length of a feeding recess per female during the incu bation, the increasing number of feeding recesses was the main reason for the increasing total time off the nest per 24 hours. however, there were striking differences between females: the mean duration over all observation days of an individual feeding recess of the lidia females ranged from 10.9 (female 4) to 15.4 minutes (female 2), with a mean of 12.9 minutes, while this was 16.7 for the island female a and 27.3 minutes for the island female b. the large differences in total time off the nest are thus due to a longer mean recess duration on the island. average recess frequency for all females was 10.6 per day with a mean recess duration of 15.5 minutes. males have more time for feeding than the incubating females. the percentage of time spent on feeding during the incubation period of both island males, the male of lidia female 3 and the non-breeding birds present in the lidia valley decreased in the course of the time (fig. 12). both island males spent more time on feeding (40.4% on average) than the lidia male 3 (31.0%) but the non-breeding geese spent the least time on feeding. most of the feeding of the incubation females took place in the afternoon and the least in the early morning (fig. 13). the males showed an opposite pattern: there was a tendency to feed more during midnight (fig. 14). breeding biology of dark-bellied brent geese 123 .g 250 e 1 t fig. 9. map of island 2. vegetation-types are indicated as well as the iocatirjn o f the brent goose nests. the camp and the observation hide. pairs a and b were studied in detail. 250 e 1 a, e 200 lh 8 150 ?? x ._ 2 100 50 always feeding within her own territory which had to be heavily defended by male a , who engaged in frequent conflicts with t h e neighbouring males (fig. 15). t h e number of conflicts showed a marked decrease in the week before hatching. intraspecijic interactions the breeding area, especially on the island, was divided into territories. male a had a relatively good territory (100% vegetation cover) while male b had a poor territory (<30% vegetation cover, fig. 9). male b in fact hardly defended a lemale 2 0 emale v lemale 4 a h a l e 5 his territory which was only used for-feeding by himself. his female almbst always left the island interactions with potential predators a, e 200 lh 8 150 ?? x ._ 2 100 50 to feed somewhere else. female a , however, was o n the island the most numerous potential pred a lemale 2 0 emale v lemale 4 a h a l e 5 300 3501 r ' i ' i ' a '~'lb'l;'tb'16'1'8'2b' " days from start of incubation fig. 10. daily recess timc during incubation of the 5 lidia femalcs ( 1 to 5 ) and the two island females ( a and b). females were non-stop observed during 24-hours periods. lldlairland 0 female 1 temale a a lemale 2 0 lemale 8 v lemale 3 t female 4 a lemale 5 - 01 " " " " " " " " " " 0 2 4 6 8 10 12 14 16 18 20 days from start of incubation fig. 1 1 . daily number of recesses during incubation. same fcmales as in fig. 10. 124 b . spaans et al. 55t 9 50 m 2 45 a, m 40 35 30 a 2 25 20 m 0 0 male a 0 male b a male 3 15 a non-breeders 1 . , , , 1 , , , . 1 , , , . 1 , . 1 1 0 5 10 15 20 25 d a y s from start of incubation fig. 12. daily percentage of total time spent on feeding by male brent geese during the incubation period. male a and b have territories on island 2 and male 3 in the lidia valley. the non breeders were also observed in the lidia valley, on the same dates as male 3. ators were the lesser black-backed gulls. pom arine skuas and long-tailed skuas were sometimes seen flying over but did not seem t o pay any attention to the breeding geese. sometimes the threat of the male was enough to keep a gull at a distance but very often a pursuit-flight followed. male b had more interactions with the lesser black-backed gulls during the incubation period than male a (fig. 16) which may be explained by the closer proximity of pair b to a gull-colony. although there is no general trend in time, there was a striking similarity in the interactions of the two males. apparently there were days on which r * a, a l time of d a y fig. 14. diurnal variation in feeding of males during the incu bation period. the percentage of total daily feeding-time of the 2 island males a and b is given per 4 hour periods. lesser black-backed gulls assailed the geese and days on which they did not. the only successful gull action that we observed on the island was a gull that managed to remove the down cover of a goose nest while the female was absent, but the male chased the gull away before it could take an egg. on other islands we saw egg-predation by the lesser black-backed gull and the arctic skua but in all cases disturbance of the geese by our presence was probably the prime cause of this predation. o n the mainland no lesser black backed gulls bred and although they regularly flew over the valley they left the geese undisturbed most of the time. the actions of male 3 were mainly directed to the pair of arctic skuas breeding c * a, l a l 0 22 time of day fig. 13. diurnal variation in feeding of females during incubation. in this figure the percentage of total daily recess 140omalea a male b 0 5 4 0 n d a y s from start of incubation fig. 15. lntraspecific interactions of males during incubation. the total number of interactions per 24 hours is eiven for the time for all females is given per 4 hour-periods. island males a and b. breeding biology of dark-bellied brent geese 125 0 male a 0 male b a male 3 lesser black-backed gull in this area (fig. 16). like the lesser black-backed gulls on the island, the skuas did not seem to be very successful in taking eggs in the lidia valley. the number of gulls and skuas present near nests in the lidia valley decreased during the incu bation period (fig. 17). it is likely that other more profitable food, for example from marine sources, became available for these birds in the course of the season. after hatching the two studied island pairs hatched their eggs on average 5 days earlier than the five studied females in the lidia valley. on island 2 the first goslings hatched on 12 july and the last on 16 july. within a few days after hatching the families left the islands. they presumably swam to the river mouths on the mainland where the food situation was more attractive. the mean observed brood size (island and river-breeders) was 2.4 ( n = 34) while clutch size was 3.0 ( n = 76), thus 80% of the eggs hatched. both island pairs studied (a and b) were less successful: only one out of the three eggs hatched in each case. the parents were capable of defending their goslings against the lesser black-backed gulls. only two times did we witness a gull taking a gosling, both times while the family was swimming in the water under windy conditions. the lidia breeders stayed in the nesting area after hatching. the banks of a small lake, about 80 0 black-backed gull oskuas 70 20 10 d a y s from start of incubation fig. 17. presence of avian potential predators at thc lidia brent geese colony. the number of times per 24 hours one or more lesser black-backed gulls and (arctic) skuas were present is given. 1 km west of the nesting site along the lidia river became one of their preferred feeding sites. the percentage of eggs hatched was 89% (16 goslings from 18 eggs in nest 1 to 5). we observed the families for more than one week. during the week only one gosling was lost. after a week's time the goslings had grown so much that predation by gulls or skuas did not seem likely. we were able to determine the breeding results of two individually marked breeding pairs soon after hatching: lidia pair 3 had one gosling (from one egg) and the pair ofya and ofyf had also 1 gosling (number of eggs unknown). because we left the area on 28 july, we d o not have data about the gosling survival of the local population studied. the large number of moulting non-breeders on the beacon islands (fig. 1) at the end of july, about 1200, suggested that there were many non-breeding birds in 1990. assuming that the study area is representative for the entire breeding population, 264 breeding pairs with 2.4 juveniles per pair and 1200 non-breeding birds gives a juvenile percentage of 2.4 x 264 (2.4 x 264) + (2 x 264) + 1200 = 27%. due to losses during growth and migration, juv enile percentage in winter area should be less than this value. observations of marked individuals in the winter area geese with known pre-breeding weights. no less 126 b. spaans et al. than 8 of the 9 geese caught in spring in taimyr were seen by different observers in the subsequent autumn and winter in western europe. as juv eniles stay with their parents during the first win ter it was possible t o determine the family size of two ringed pairs and one ringed female: the pair rpgc and rpga was accompanied by five full grown juveniles (ameland, netherlands), the pair rpgh and rpgk had no juveniles (south east england) and the female rpgn was seen with an unringed male and 1 juvenile (texel, netherlands) (table 1). geese with unknown pre-breeding weight but with known breeding results soon after hatching. both pairs of this category were seen again. lidia pair 3 was seen with one full-grown juvenile (coast of groningen, netherland) and pair ofya and ofyf had one juvenile as well (schiermon nikoog, netherlands). this means that both pairs raised their single gosling successfully because both were seen with only one gosling soon after hatching in taimyr. discussion the late arrival of brent geese in taimyr (fig. 7), compared with the departure from the spring staging areas (fig. 6), means that there must be staging areas along the northern coast of russia. no staging areas are known in the baltic (kumari 1979; lampio 1979). given the fact that in taimyr almost all vegetation was covered with snow at the beginning of june, it is likely that the staging areas are situated far more to the southwest where snowmelt starts earlier. kistchinski & vronski (1979) suggest that spring migration between the white sea and taimyr is a non-stop migration, and the dates on which migration is seen along the north russian coast correspond with our arrival dates in taimyr. this means that the white sea is most likely the intermediate staging area. given the early departure from the wadden sea, the geese must have spent almost three weeks on these staging grounds in 1990. this period is long enough to replenish the body reserves used during the first part of the migration (ebbinge & spaans, 1992). the mean female body-mass at arrival in tai myr was 1496 g (table l ) . this body-mass is about 250g heavier than lowest mean wadden sea body-mass (first half of april) and about 140g heavier than mean winter body-mass (ebbinge et al. 1982), so it is clear that the geese at arrival in 1990 did have reserves. however, it is likely that in years when departure weights in the wadden sea are higher and weather during migration is comparable, the body condition on arrival in tai myr will improve. since the departure weights were low in 1990 (fig. 5 ) , 1496 g will probably be a rather poor pre-breeding condition. brent geese started breeding very soon after arriving in taimyr (fig. 7). these observations are in sharp contrast to findings in raveling (1978), fox & madsen (1981), ely & raveling (1984) and gauthier & choinibre (1990) where species such as the cackling goose branta can adensis minima, the two subspecies of the white fronted goose anser albifrons and the greater snow goose anser caerulescens atlantica spend 10 to 20 days on the breeding grounds before egg laying starts. as with the brent geese in our study, however, ross geese anser rossii and lesser snow geese anser c. caerulescens start to lay eggs within 3-5 days after arrival (raveling 1978). most brent geese bred on small off-shore islands but some were breeding on the mainland along rivers. if there had been arctic foxes, the island birds would have had a safer location than the birds on the mainland, although most of the islands would have been easily accessible to foxes over the still frozen sea during the first two weeks of incubation. the developing vegetation in the river valleys and on the outer islands seemed to be much more attractive to geese than the vegetation on the inner islands, where nest density was highest (fig. 8). the fact that the majority of the geese did not choose to breed in the best feeding-areas may be the result of a difference i n potential predation pressure and/or difference in availability of the nest-sites soon after the arrival of the geese. the melting snow in spring may flood river-valleys and the low-lying outer islands to a large extent in the second half of june. because of the very short summer season at this latitude (74"n), delayed nesting causes problems at the end of the season when goslings must be able to fly before changing weather conditions make feeding impossible. due to large territories around the nest where the females feed during incubation, nest density is low (maximum 3.9 nests/ha) compared for instance to the barnacle geese branta leucopsis on svalbard where nest density on breeding islands has been reported t o be 84.7 nests/ha on breeding biology of dark-bellied brent geese 127 sen et al. (1989): four female light-bellied brents deserted their nests 19 days after the start of incubation within 32 hours after a snow storm. predation of eggs is more likely to occur when the recesses are long (inglis 1977; prop et al. 1984; raveling 1989; thompson & raveling 1987). we never observed that a male sat on the nest while the female was feeding as is described for whis tling swans cygnus c . columbianus (hawkins 1986). the preference of the females to feed during mid-day, the warmest part of the day (fig. 13), may be determined by the fact that the eggs will cool less at that time when the nest is left for longer periods. this diurnal rhythm has also been found in light-bellied brent geese (madsen et al. 1989) and in other goose species (prop et al. 1980; aldrich & raveling 1983; thompson & raveling 1987). the abundant presence of down in the nests of brents clearly is an adaptation to their low nest-attentiveness. thompson & raveling (1988) showed that eggs in black brant nests cooled less than those in the nests of the more attentive emperor and cackling goose. some males spent a considerable amount of time in defending their territory against neigh bouring males (fig. 15). as the territory of male b was probably not attractive for the neighbours, male b had less conflicts than male a . the decrease in the number of conflicts between the males in the week before hatching could be the result of an improving food situation at that time; intrusion pressure decreased and defending every square metre of the territory became less impor tant. spring was early in 1990 (fig. 2) and the decreasing time spent on feeding by the males and non-breeders during the incubation time indicates that the food situation was improving during the course of the incubation period (fig. 12). the difference in male feeding time between the island and the lidia colony might result from the poorer food situation on the island. because the males of breeding pairs had to defend and guard their families after hatching, it was necessary that they had reserves for this period. this might explain the difference in feeding time between breeding and non-breeding birds. the average feeding per centage of non-breeders observed by madsen et al. (1989) during the incubation period was 53.3%; in the lidia situation it was only 28.0%. the overall picture of decreasing feeding time, resulting in low feeding percentages (fig. 12), will average (prop et al. 1984). here the geese breed in colonies on islands and fly to the mainland for feeding. madsen et al. (1989), however, found a breeding density of only 0.5 nests/ha for light bellied brent geese branta bernicla hrota on the tusendyane islands, svalbard. the time a female spends off her nest will depend on her body reserves and the quality and quantity of the food she is able to gather during the feeding recesses. concerning the food, the river-valley birds had a better local food supply than the island birds. this might explain part of the differences in recess time (fig. 10). on the island female a fed in her own territory whereas female b , who had a poorer territory (fig. 9), in most cases flew to the mainland or other adjacent islands to feed, resulting in longer nest recesses (27 minutes). this illustrates the importance of a territory with sufficient food. madsen et al. (1989) found for the light-bellied brents on svalbard an average recess frequency of 6.7 per 24 hours and a mean recess length of 19.2 min. this means that on svalbard the females spent on average less time off their nest (129 min per day) than the dark-bellied brents in our situation (10.6 recesses of 15.5 rnin per day = 165 min). this difference can be the result of a difference in digestibility of the food. madsen et al. report that the food of the brent on svalbard partly consists of mosses. we seldom saw the geese eating mosses in our area. the nest attentiveness of the female black brant branta bernicla nigricans reported by thompson & raveling (1987) is about the same as for the dark-bellied but the feeding time per day is shorter, caused by the low percentage of feeding during recesses (6496, based on 3 recesses). the longest feeding time (239 minutes per day) is reported for the light-bellied brents in canada (afton & paulus 1993). the mean daily feeding time for our island female b however was 238 minutes. in the latter case only one out of the three eggs hatched so 238 minutes might be too long but the example shows that such a long feeding time was also possible in our situation. brent geese are less attentive to their nests than other goose species (prop et al. 1984; afton & paulus 1993). the females apparently do not have sufficient body reserves to fast during incubation. the dependence on local food during incubation makes brent geese very vulnerable for bad weather conditions during this period (barry 1962). the effect of not being able to feed suf ficiently during incubation was observed by mad 128 b . spaans et al. be indicative for a favourable food situation in the course of the season. during spring staging it is not unusual that brent geese spend over 89% of the daytime on feeding (prop & deerenberg 1991), this means about 16 hours feeding per day. in order to achieve the same feeding time in the 24 hours daylight in taimyr, on average 67% of the time should be spent feeding. because of the absence of arctic foxes, lesser black-backed gulls and skuas were the only poten tial predators. madsen et al. (1989) observed a heavy egg-predation by arctic skuas on svalbard, but in 92% of the cases predation took place during disturbance of the brent goose colony by polar bears ursus maritimus. although egg and gosling predation by avian predators was also a constant danger for the geese in taimyr, they were well able to defend their clutch and young goslings. therefore predation must be considered as a factor of only minor importance in 1990 in our situation. the observations of the two marked pairs, each with one full-grown juvenile in western europe while both pairs had only one gosling after hatching in taimyr, are an indication that gosling surviving was indeed high in 1990. we observed a large number of non-breeders in our study area (1200). these birds started moulting already during the hatching period. because we never observed complete nest failure, we suspect that most of these birds did not even attempt to breed. this means that 69% of the local population failed to produce eggs. combining the taimyr and western europe data the estimated dark-bellied brent geese popu lation size in january 1990 was 220,000 birds (st. joseph 1991). because virtually no dark-bellied brent nested successfully in 1989, there were no yearlings in the population in 1990. therefore 100% of the birds of the population were theor etically capable of breeding. this means that there were 110,ooo potential breeding pairs in the sum mer of 1990, mortality during spring and spring migration not taken into account. in autumn 1990 the percentage of juveniles was 20% and the mean number of juveniles per pair was 2.4. this means that in every 100 brents there were 100 20 = 80 adults (or 40 pairs) of which 20/2.4 = 8.33 were successful pairs. so the percentage successful parents was 8.3/40 = 20.8%. the total number of pairs that brought one or more juveniles to the wintering-grounds was 0.208 x 110,000 = about 23,000 pairs. there has been discussion about the occurrence of a density-dependent reduction in the pro portion of successful breeding pairs in good breed ing seasons (30% juveniles or more) (ebbinge 1985; summers & underhill 1991), but 23,000 successful pairs comprise only a fraction of the predicted number of successful pairs in a good breeding season (according to summers & under hill, without density-dependent reduction, it is 44% of the predicted number, and according to ebbinge it is about 60% when density-dependent reduction occurs). thus relatively few pairs man aged to raise juveniles successfully in 1990. in taimyr snowmelt was early (fig. 4), the mean temperature in june and july was high (fig. 2), arctic foxes were absent, predation by birds (gulls and skuas) was probably of little importance and the food-rich riverbanks could easily hold more breeding pairs. if predation and/or weather conditions would be the most important factors determining the breeding success (barry 1962; roselaar 1979; summers 1986; boyd 1987; dhondt 1987; greenwood 1987; owen 1987). 1990 should have been a very good breeding year. the fact that population-breeding success was only moderate indicates that another factor played an important role in 1990. it seems plaus ible that this was the poor pre-breeding condition of the geese (fig. 5). although mean condition is poor, there are always, due to the variation in the body-mass, individuals with a condition better than average (table 1). if only females in better condition have sufficient reserves to start breed ing, we can explain the intermediate breeding success on population scale. under this hypoth esis the intermediate breeding success is not the result of many breeding pairs that were mod erately successful but of a relatively small number successful breeding pairs and many pairs that did not lay eggs at all. in that case breeding birds were pairs in relatively good condition. the fact that the local breeding birds in our study seemed to have been successful is in agreement with this explanation. also, the observations of the marked geese with known pre-breeding weight in western europe, where the heaviest female (1610 g) had five, an intermediate female (1560 g) had one, and the lightest female (1380 g) had no juveniles, correspond with this hypothesis. acknowledgements. we are very grateful to, y . y. syroech kovskiy, institute for evolutionary animal morphology and breeding biology of dark-bellied brent geese 129 ecology in moscow. who organized and gave us the opportunity to participate in the international exhibition to the taimyr peninsula. n. vronski. a. abolitz, g. boere, p. prokosch and j . veen played important roles in the organisation of the expedition and co-operation with the russians. j . koenes and his carpenters. zoological laboratory of the university of groningen. prepared a prefabricated observation hut suitable for arctic conditions. we are also grateful to the many people who assisted in collecting data presented in this paper. the catching of geese in spring on terschelling has been carried out by j . burgers and g. miiskens. in taimyr. v. grabowski, y. kokorev, a. ivanov-smolenski and a. moroz helped with the observations. m. ryhlikova collected data on the occurrence of lemmings. h. schmauder was important as an interpreter and a. grosheva prepared excellent meals. the figures hdvc been prepared by d. visser. comments by r . h. drent. j. tinbergen and two anonymous referees greatly improved this paper. references afton. a . d. & paulus. s. l. 1993: incubation and brood care. pp 62-108 in batt. b. d. j . , afton, a. d . . anderson. m. g.. ankncy. c. d.. johnson, d. h . , kadlec. j. a . & krapu, g. l. (eds.): ecology and management of brccding water fowl. univ. of minnesota press. minneapolis. aldrich. w. & raveling. d. g. 1983: effects of experience and body weight on incubation behavior of canada geese. auk 100. 670-679. anthony. r. m.. flint. p. l. & sedinger, j. s. 1991: arctic fox removal improves nest succcss of black brant. wildl. soc. bull. 19. 176184. barry. t . w. 1962: effect of late seasons on atlantic brant reproduction. j , wildl. manage. 26.. 1+26. boyd, h. 1987: d o june temperatures affect the breeding success of dark-bellied brent geese? bird study 34, 11s 159. cramp, s . & simmons, k. e. l. (eds) 1983: handbook of the birds of europe. the middle east and north africa, vol 3. oxford university press. oxford. dhont, a. a . 1987: cyclcs of lemmings and brent geese branfa 6. bernicla: a comment on the hypothesis of roselaar and summers. bird study 34. 151-154. ebbinge. b. s . 1985: factors determining the population size of arctic-breeding gcese. wintering in western europe. ardea 73, 121-128. ebbingc. b. s . 1989: a multifactorial explanation for variation in breeding performance of brent geese. ibis 131, 196204. ebhinge, b. s. 1990: reply by barwold s . ebbinge. fbis 132, 48 1-482. ebbinge, b. s. & spaans, b. 1992: the importance of body reserves accumulated in spring staging areas in the temperate zone for breeding of dark-bellied brent geese branfa b . bernicla in the high arctic. in: ebbinge. b. s. 1992: population limitation in arctic-breeding geese. ph.d. dissertation. uni versity of groningen. pp 144-155. ebbinge, b., st.joseph, a., prokosch, p. & spaans, b. 1982: the importance of spring staging areas for arctic-breeding geese. wintering in western europe. aquila 89. 249-258. ely, c. r. & raveling, d. g . 1984: breeding biology of pacific white-fronted geese. j. wildl. manage. 48(3). 823-837. fox, a. d. & madsen, j . 1981: the pre-nesting behaviour of the greenland white-fronted goose. wildfowl 32, 48-54. gauthier, g. & choinikre. l. 1990: energy reserves and repro ductive performance in greater snow geese. acta xx con gressus internationalis ornithologici (supplement). p. 425. greenwood, j . j. d . 1987: three-year cycles of lemmings and arctic geese explained. nafure 328. 577. hawkins, l. l. 1986: nesting behaviour of male and female whistling swans and implications of male incubation. wild fowl 37, 5-27. inglis, i . r. 1977: the breeding behaviour of the pink-footed goose: behavioral correlates of nesting success. anim. behao. 27, 747-764. kistchinski. a. a. & vronski, n. v. 1979: migrations of brant. in: migrations of birds of eastern europe and northern asia, ciconiiformes-anseriformes. publishing house nauka. moscow. pp 188-194. kumari. e. e. 1979: status of branfa bernicla bernicla on passage in baltic ussr. in smart, m. (ed): procecdings of the first technical meeting on western palearctic migratory bird management, paris 1977. slimbridge: international waterfowl research bureau. lambeck, r. h. d. 1990a: the applicability of age ratio and brood size counts in population dynamic studies of the brent goose branfa 6. bernicla. ardea 78(3). 414-425. lambeck. r. h . d. 199ob: differences in migratory pattern and habitat choice between social classes of the brent goose branfa 6. bernicla. ardea 78(3). 426440. lampio, t . 1979: status of branfa bernicla bernicla in finland. in smart, m. (ed). proceedingsof the first technical meeting on western palearctic migratory bird management, paris 1977. slimbridge: international waterfowl research bureau. madsen. j.. bregnballe, t . & mehlum, f. 1989: study of the breeding ecology and behaviour of the svalhard population of light-bellied brent goose branta bernicla hrofa. polar res. 7, 1-21. owen. m. 1987: brent goose branla 6 . bernicla breeding and lemmings a re-examination. bird study 34. 147-149. prop, j . & deerenberg. c. 1991: spring staging in brent geese branfa bernicla: feeding constraints and the impact of diet on the accumulation of body reserves. oecologia 87, 1s28. prop, j., van eerden. m. r.. daan. s.. drent. r. h.. tinber gen, j. m.. st.joseph. a. m. 1980: ecology of the barnacle goose branfa leucopsis during the breeding season: pre liminary results from expeditions t o spitsbergen in 1977 and 1978. pp. 50-1 12 in proc. norwegian-netherlands symp. svalbard. arctic centre. groningen. prop, j., van eerden, m. r . & drent, r. h. 1984: reproductive success of barnacle goose branfa leucopsis in relation to food exploitation on the breeding grounds. western spits bergen. nor. polarinst. skr. 181, 87-117. raveling, d. g. 1978: the timing of egg laying by northern geese. auk 95,294-303. raveling, d. g. 1989: nest-predation rates in relation to colony size of black brant. j. wildl. manage. 53(1), 87-90. roselaar, c. s. 1979: fluetuaties in aantallen krombek strandlopers calidris ferruginea. wateruogels 4 , 202-210. ryhlikova, m. e. 1993: lemmings in the west taimyr arctic: population density, distribution of territories and relation with other animals. bericht iiber die deutseh-russischen biologen-expeditionen naeh taimyr in den jahren 1989.1990 und 1991. wwf-deutsehland, husum. st.joseph, a. k. m. 1982: review of the status of branfa bernicla bernicla. in scott, d. a. & smart, m. (eds). pro ceedings of the second technical meeting on western pale arctic migratory bird management, paris 1979. slimbridge: international waterfowl research bureau. 130 b . spaans et al. st.joseph, a . k. m. 1991: status of the brent goose branta bernicla, 198689, dark-bellied brent. iwrb goose research group bulletin. 1 . 4-5. summers, r. w. 1986: breeding production of dark-bellied brent geese branta b . bernicla in relation to lemming cycles. bird study 33, 105-108. summers, r . w. & underhill, l. g. 1987: factors related to breeding production of brent geese and waders on the tai myr peninsula. bird study 34, 161-171. summers, r. w. & underhill, l. g . 1990: multivariate analyses of breeding performance in dark-bellied brent geese branra b. bernicla; comment. ibis 132, 477-481. summers, r. w. & underhill, l. g . 1991: the growth of the population of dark-bellied brent geese branra b . bernicla between 1955 and 1988.1. appl. ecol. 28, 584-585. thompson, s . c. & raveling, d. g . 1987: incubation behavior of emperor geese compared with other geese: interactions of predation. body size. and energetics. auk l04. 707-716. thompson, s. c. & raveling. d . g. 1988: nest insulation and incubation constancy of arctic geese. wildfowl3y, 124-132. holocene glacial advances and moraine formation at albrechtbreen, edgebya, svalbard lars ronnert and jon y. landvik ronnert, l. & landvik, j . y. 1993: holocene glacial advances and moraine formation at albrechtbreen, edge~ya, svalbard. polar research 12(1), 57-63. terrace remnants close to the marine limit as well as two separate moraine ridges are observed in front of the glacier albrechtbreen. the stacking of marine sediments from an original elevation of ca. 60-80111 a d . into the little ice age moraine gives evidence for a considerably smaller glacier following the early holocene deglaciation compared to that of the present. the outer moraine is composed of glacial diamicton. radiocarbon datings of whale ribs, shell fragmedts and a log taken from sediment in front of albrechtbreen indicate that the initial deglaciation occurred before 9,400 b.p. and that the outer moraine was formed during a younger holocene glacial advance. lithological differences between the two moraine ridges suggest that the first ice advance occurred during a period with limited permafrost, whereas permafrost was more extensive during the little ice age. lars ronnert, department of geology, university of goteborglchalmers university of technology, s412 % goteborg, sweden; jon y . landvik, agricultural uniuersity of norway, department of soil sciences, p . 0 . box 5028, n-1432 a s , norway ' ' * p ~ ~ a r ~ ~ ~ ' ' albrechtbreen is the northern land-based outlet glacier from the ice cap edgeayjakulen on edgeaya, eastern svalbard (fig. 1). in front of albrechtbreen there are terrace remnants and two separate moraine ridges characterized by differences in sediments, morphology and vegetation. river cuttings in front of albrecht breen expose sediment thicknesses in excess of 20m in the terrace remnants and in the outer moraine. glaciotectonic stacking of marine sedi ments caused the little ice age moraine to be more than 5 0 m high. in this paper we discuss the genesis and chronology of the albrechtbreen moraines. the albrechtbreen area the morphology and sediments in front of albrechtbreen are generalized in fig. 2 and described below. the terrace and the lower plain distal from the moraine complex is a terrace 82 m a.s.1. (figs. 3 and 4), which we estimate to be close the marine limit (cf. mangerud et al. 1992). the ice-distal slope of the terrace dips 16", reach ing a silt and clay plain with marine shore deposits fig. 1. map of edgebya. the investigated area is marked with a solid square. dotted lines indicate the present ice cover. the inset map shows the svalbard archipelago (e = edge~ya, s = spitsbergen, vm = van mijenfjorden, l = lomfjorden, i = isfjorden). 58 l. ronnert & j . y . landvik silt and marine i outer moraine i little ice age moraine i i i i i i i i i 5 120 i i i slumping and flows m m o n breen p .. 0, i ' i " _ _ 1 i 4 i i rhnnnsl u u) 90 60 fig. 2. generalized interpreted section in front of albrechtbreen as discussed in text. at the surface at an altitude of approximately 60m. both the terrace remnants and the lower silt and clay plain show a smooth surface almost completely covered with vegetation. the entire surface is cryoturbated. outer moraine n fig. 3. generalized geomorphological map from the inves tigated area in front of albrechtbreen (fig. 1). the white area between the debris-covered ice front and the little ice age moraine is a proglacial depression into which slumping and flows occur from both the ice front and the moraine. the area outside the terrace and the moraines is sloping towards the silt and clay plain mentioned in the text. the map is based on field observations and infrared air photographs s90 2454 and 2455 from norsk polarinstitutt, enlarged to a scale of 1 : 12,500. "c samples are referred to site 2401 (see table 1). the section cut by the river (fig. 4) is 20 m high and composed mainly of coarse, foreset-bedded gravel, interpreted to be of glaciofluvial origin. this is the lowermost quaternary stratigraphic unit recorded in the area. the upper l m , however, has imbricated pebble layers sloping gently down valley, indicative of a shore deposit. the valley side to the northeast is composed of weathered shale. the other terrace remnant, to the southwest, reaches an altitude of 81 m and is composed of sand and gravel with foreset beds indicating deposition from the general direction of the present drainage system (to the northwest). the outer moraine this moraine ridge is situated immediately out side the pronounced little ice age moraine (fig. 3) and reaches an altitude of 85 m a.s.1. the ice proximal part of the outer moraine, where not covered by the little ice age moraine, slopes approximately 8" to 10" up glacier while the ice distal side slopes approximately 25" down towards the silt and clay plain 15 to 20 m below. escarp ments, probably representing earlier detachment of sediment flows, occur most frequently on the ice-distal slope. the ridge surface is characterized by small depressions, up to 10m in diameter, interpreted to be kettle holes. some depressions seem to be forming at present, but the section along the river shows no indication of remnant glacier ice in the ridge. the surface morphology is generally fresh with forms not yet levelled out by the intense solifluction processes that are typi cal in the area (figs. 5 and 6). the older moraine contrasts both the flat surface of the terrace and holocene glacial advances and moraine formation 59 fig. 4. view from the little ice age moraine showing the outer moraine, the ter race and the lower silt and clay plain. the thrust plane differentiating the terrace and the outer moraine is vis ible but is better seen in fig. 5 . note also the differences in vegetation and surface morphology. fig. 5 . the thrust plane (dashed line) in the section on the north side of the river is emphasized by the dif ference in sediment colour and slope gradient. the surface morphology and degree of vegetation cover on the outer moraine is seen in the lower half of the photograph. the location of sample 87-806 is marked. fig. 6 . view towards the little ice age moraine showing its composition of stacked marine sediments. the surface morphology and vegetation cover on the outer moraine is seen in the lower half of the photo graph. 60 l . ronnert & j . y. landoik fig. 7. the contact between the terrace sediments and the outer moraine is seen as an unconformity (arrows) between the stratified gravel and the overlying clayey diamicton. the sharp relief of the little icc age moraine (see below). the extent of vegetation cover is intermediate between the terrace and the non vegetated little ice age moraine. the section on the western side of the river from albrechtbreen shows that the sediments in the ridge consist predominantly of a clayey dia micton, discordantly overlying glaciotectonized glaciofluvial gravel (fig. 7 ) , probably belonging to a glacially overrun proximal part of the terrace described above. the contact between the gla ciofluvial gravel and clayey diamicton is a shear plane oriented 060°/200s, i.e. dipping toward albrechtbreen. on the north side of the river (fig. 3 ) a similar stratigraphic relation on a larger scale is observed. the underlying gravel is cut by ravines (fig. 5) while the diamicton unit above the thrust plane has a lower surface gradient. two radiocarbon dates from whale ribs found on the moraine surface have been obtained (table 1). sample 87-806 is from a one metre long piece of whale rib picked from the eroded moraine surface inside the terrace (fig. 8). the other i fig. 8. photo of the whale rib (sample 87-806) dated to 9,360 & 105 b.p. the bar is divided into 0.1 m long segments. sample, 87-807, is from the diamicton surface along the river, only 20 m outside the subrecent moraine. both bones are interpreted to have been released from the diamicton by fluvial erosion related to the subrecent or present meltwater outlet of albrechtbreen. the bones must have been picked up inside the present limit of albrechtbreen and redeposited during the advance that formed the moraine. these dates are thus maximum dates for this glacier advance. both dates, 9,360 f 105 and 8,635 f 125 b.p. respectively (see table l), are also minimum dates of the early holocene deglaciation. the little ice age moraine just outside and paralleling the front of albrecht breen is a moraine with high relief, c. 50 m, that we assume to have been formed during the little ice age. it has a crosscutting relationship with the outer moraine (fig. 3 ) . the western part of the moraine is composed of stacked sheets of marine sediments (fig. 6 ) . this stacking can be table i. radiocarbon dates. a marine reservoir age correction of -440 years has been made on the shell and whale bone samples (cf. mangerud & gulliksen 1975). sites are referred to ponam-number 2401. elevation field no. site (m a d ) age (radiocarbon material lab. no. yr b.p.) 87-806 c 68 87-807 d 61 87-810 j 72 87-808 g 94-103 87-809 h 103-133 whale rib t-9910 9,360 2 105 whale rib t-9911 8,635 2 125 m t-9912 9,405 t 70 shell frag. lu-3374 9,260 2 140 shell frag. lu-3375 9,110 2 110 holocene glacial advances and moraine formation 61 seen in ravines on the ice-distal side of ridges and they show that large sediment volumes are present and that there is no ice core in this part of the moraine. however, an ice core has been observed in the more morphologically subdued north eastern part of the moraine. restricted to this area, there are wet and dark spots on the slopes that typically occur in ice-cored moraines when they melt. there is no vegetation on the moraine surface. in the western part of the moraine, up to 50 m of marine sediments have been stacked up during the time period that is represented by the ice advance during the little ice age. shell fragments ( m y a truncata, hiatella arctica, balanus s p . ) and whale bones found up to the crest of the moraine demonstrate a marine origin. shell and driftwood samples yielded radiocarbon dates older than 9,100 b.p. (table l ) , consistent with the early holocene deglaciation. discussion the terrace is built up close to the marine limit of the early holocene deglaciation, which compares with other marine limit determinations on n e edgeoya (mangerud et al. 1992). available sea level displacement curves from eastern svalbard show a rapid glacioisostatic rebound following deglaciation (e.g. salvigsen 1978, 1981; forman 1990; mangerud et al. 1992). glaciomarine sedi ments deposited at or only a few tens of metres below the marine limit must have been deposited approximately within one thousand years after deglaciation. this is consistent with our radiocar bon dates that show minimum ages of both the deglaciation and the marine limit (table 1). the formation of the little ice age moraine is assumed to have terminated approximately 1900 a.d. which was the time when most glaciers in svalbard had their maximum holocene extension (salvigsen & osterholm 1982; boulton et al. 1982). it is more problematic to estimate the age of the outer moraine which we believe to have been formed considerably earlier than the little ice age. this interpretation is supported by (a) the striking difference in vegetation cover and mor phology and (b) the crosscutting relationship between the two moraine ridges (fig. 3) that possibly shows a slight shift in ice dome position of the glacier edge~yjbkulen during the time interval between their formation (cf. dugmore & sugden 1991). the outer moraine represents more than a small readvance during general early holocene de glaciation because (a) there is a difference in vegetation cover and morphology between the moraine ridge and the adjacent terrace and valley slopes, and (b) large volumes of marine sediments at high altitudes in the little ice age moraine indicate that the glacier had receded well inside the present ice margin at the time shown by the radiocarbon dates. our interpretation suggests that the glacial impact on the marine sediments was different during the two glacial advances. during the older advance the glacier eroded and homogenized sediments into a diamicton unit whereas large quantities of marine sediments were left intact beneath the glacier. during the subrecent advance these marine sediments were glacially pushed and stacked but not homogenized. this implies a difference in resistance within the sedi ments crossed by the glacier. since both glacial advances occurred over more or less the same stratigraphic sequence, we propose that this was due to a difference in permafrost distribution. models exist for proglacial stacking of both frozen (e.g. bluemle & clayton 1984) and unfrozen sedi ment (e.g. van der wateren 1985), but we believe that the homogenization of marine sediments into a diamicton close to the glacier margin during the older advance most likely occurred with limited permafrost. stacking of marine sediments into the little ice age moraine therefore, assuming a different permafrost distribution during the two glacial advances, occurred when the permafrost reached deeper. the permafrost distribution through time on svalbard has been generalized by landvik et al. (1988) who proposed a zone of no or discontinuous permafrost along the coast line that has recently emerged from the sea. it is reasonable to believe that this situation also applied for the sediments in front of albrecht breen in the early holocene before permafrost was established. the paleoclimatic setting of the svalbard archi pelago during the holocene, the time when the interpreted glacial advances of albrechtbreen occurred, has been interpreted mainly through datings of glacial variations on spitsbergen (fig. 1). an advance of paulabreen in van mijen fjorden (fig. 1) occurred approximately 7,850 to 8,550b.p., but was interpreted as a result of a 62 l. ronnert & j . y . landvik surge (punning et al. 1976) and is thus of no reliable climatic significance. beget (1983) sug gested that a world wide climatic cooling of about the same amplitude as the recent neoglaciation occurred between 8,500 and 7,500 b.p. troickij & punning (1984) reinterpreted the age of an ice advance in the lomfjorden area, ne spitsbergen, to about 7,800b.p. salvigsen et al. (1990) reported glacier advances on two lowland pen insulas on the northern shore of isfjorden (fig. l ) , western spitsbergen. one glacier, esmarkbreen, advanced shortly after 9,500 b.p. in front of the other glacier, wahlenbergbreen, a moraine was formed subsequent to 9,000 b.p. and there were, as in this study, differences in vegetation cover and the effect of cryogenic processes between the older holocene moraine and the little ice age moraine. werner (1988) made a thorough review of holocene glaciation in spitsbergen. based on lichenometry, he found four episodes of moraine formation that approximated 1,500 b.p., 1,000b.p., 650b.p.. and during the last centur ies. from studies of lacustrine sediments in linncvatnet, western spitsbergen, svendsen & mangerud (1992) concluded that glaciers upstream from this lake began forming some 2,000-3,000 years ago. thus the existing dates on glacial advances from spitsbergen point in two directions, one toward early holocene, 9,500 to 7,800 b.p. (punning et al. 1976; troickij & pun ning 1984; salvigsen et al. 1990), and one toward late holocene, from 3,000 b.p. (werner 1988; svendsen & mangerud 1992). the occurrence of the thermophilous mollusc mytilus edulis might be the best available indi cator of warmer seasurface temperatures than at present. radiocarbon datings of mytilus edulis from spitsbergen have been reviewed by sal vigsen et al. (1992) and show warmer marine conditions between 9,500 and 3,500 b.p., and during a short period around l,ooob.p. the warm period was probably shorter on eastern svalbard due to differences in sea currents. based on findings of mytilus edulis this warm period is preliminarily interpreted by hjort et al. (1992) to have lasted from 8,500 to 5,000 b.p. werner (1988) argued that holocene glacial advances on spitsbergen correlate with cool cli mate. warren (1991) concluded from his work in west greenland that land-based glaciers respond primarily to changes in summer temperature. calving glaciers are, on the other hand, not reli able as climatic indicators (warren 1991). surging glaciers are common in svalbard today (cf. hagen 1988; liestel 1988) and a surging albrechtbreen cannot be excluded. increased winter precipi tation, possibly as a response to increased sea surface temperatures, could have triggered an advance. it is also possible that a different spatial distribution of winter precipitation changed ice divide positions (cf. dugmore & sugden 1991), thereby increasing the amount of ice drained by albrechtbreen. the discussion above shows that the most con servative age estimate of the glacial advance that formed the outer moraine is bracketed between 8,635 2 125b.p. and the little ice age. however, discussions on the permafrost dis tribution points to a glacial advance during the first half of the holocene, while most general paleoclimatic assessments favour an advance after 3,000 b.p. the redeposition of marine sediment in the little ice age moraine shows that albrechtbreen had receded beyond its present margin after the deglaciation, probably due to calving during the deglaciation when sea level was 82 m higher than at present. the extent of the maximum readvance during the holocene may be compared to advances of more than 12 km reported from some places in spitsbergen during the little ice age (boulton et al. 1982). summary based on the evidence and discussion presented above, we suggest the following scenario for the albrechtbreen area during the holocene (fig. 2). the investigated area was deglaciated and a glaciofluvial delta was built up in front of the glacier close to the marine limit, 82 m a.s.1. the glacier margin receded well beyond its present position between 9,405 2 70 and 8,635 ? 125 b.p., as suggested by the radiocarbon dates (table 1). later, between 8,635 k 125 b.p. and the little ice age, albrechtbreen advanced and partly overran the delta. a moraine was deposited along the ice margin of that time, and the glacier receded once again to an unknown position. during the little ice age, albrechtbreen advanced once more, stacking the marine sedi ments into 50 m high moraine ridges parallel to the ice margin, after which a slow glacial retreat began. holocene glacial advances and moraine formation 63 acknowledgements. this is a contribution to the european science foundation project: polar north atlantic margins, late cenozoic evolution (ponam). we thank all ponam contributors for good working conditions and especially c. hjort and 0. salvigsen, who together with j. landvik were responsible for transportation and logistin in cooperation with the norwegian polar institute. l. ronnert was funded by the swedish natural science research council (nfr), while j . landvik’s participation was supported by the norwegian research council for science and humanities (navf), norwegian petroleum directorate, norsk hydro, statoil norge, and saga petroleum. helicopter transport was financed through a grant from the european commission to the euro pean science foundation. s. rasmussen participated in the initial part of the field work. r. stevens and j. i. svendsen reviewed the manuscript. references beget, j. e. 1983: radiocarbon-dated evidence of worldwide early holocene climate change. geology 11, 389-393. bluemle, j. p. & clayton, l. 1984: large-scale glacial thrusting and related processes in north dakota. boreas 13,27%300. boulton, g. s., baldwin, c. t., peacock, j . d., mccabe, a. m., miller, g., jarvis. j., horsefield, b., worsley. p., eyles, n., chroston, p. n., day, t. e., gibbard, p., hare, p. e. & von brunn, v. 1982: a glacio-isostatic facies model and amino acid stratigraphy for late quaternary events in spits bergen and the arctic. nature 298, 437-441. dugmore, a. j. & sugden, d. e. 1991: do the anomalous fluctuations of s6lheimajokull reflect ice-divide migration? boreas 20, 105-113. forman, s. 1990: post-glacial relative sea-level history of north western spitsbergen, svalbard. geol. soc. a m . bull. 102, 1580-1590. hagen, j. 0. 1988: glacier surge i n svalbard with examples from usherbreen. norsk geografisk tidsskrift 42, 203-213. hjort, c., adrielsson, l., bondevik, s., landvik, j. y., man gerud, j . & salvigsen, 0. 1992: mytilus edulis on eastern svalbard dating the holocene atlantic water influx maxi mum. lundqua report 35, 171-175. landvik, j . y., mangerud, j. & salvigsen, 0. 1988: glacial history and permafrost in the svalbard area. pp. 194-198 in senneset, k. (ed.): proceedings. 5th international conference on permafrost, trondheim, augur 1988. tapir, trondheim. liestbl, 0. 1988: the glaciers in the kongsfjorden area, spits bergen. norsk geogrqlvk tidmkrift 42, 231-238. mangerud, j. & gulliksen, s. 1975: apparent radiocarbon age of recent marine shells from norway, spitsbergen and arctic canada. quat. res. 5,265-273. mangerud, j., bondevik, s., ronnert, l. & salvigsen, 0. 1992: shore displacement and marine limits on edgeeya and barentsbya, eastern svalbard. lundqua rep. 35, 51-60. punning, j.-m., troitsky, l. & rajamae, r. 1976: the genesis and age of the quaternary deposits in the eastern part of van mijenfjorden, west spitsbergen. geogrqlvka foreningens i stockholm forhandlingar 98, 343-347. salvigsen, 0. 1978: holocene emergence and finds of pumice, whalebones and driftwood at svartknausflya, nordaustlan det. norsk polarins. arbok 1977,217-228. salvigsen, 0. 1981: radiocarbon dated raised beaches in kong karls land, svalbard, and their consequences for the glacial history of the barents sea area. geog. ann. 63a, 283-291. salvigsen, o . , elgersma, a., hjort, c., lagerlund, e., liestbl, 0. & svensson, n.-0. 1990: glacial history and shoreline displacement on erdmannflya and bohemanflya, spitsber gen, svalbard. polar res. 8, 261-273. salvigsen, 0.. forman, s. l. & miller, g. h. 1992: thermo philous molluscs on svalbard during the holocene and their paleoclimatic implications. polar res. 21, 1-10. salvigsen, 0. & osterholm, h. 1982: radiocarbon dated raised beaches and glacial history of the northern coast of spits bergen, svalbard. polar res. 1, 97-115. svendsen, j . 1. & mangerud, j. 1992: paleoclimatic inferences from glacial fluctuations on svalbard during the last 20.w years. climate dynamics 6 , 213-220. troickij, l. s. & punning, j.-m. 1984: on the early holocene stage of glaciation in spitsbergen. marerialy gljaciologiceskich irsledouanij 50, 203-208. (in russian. internal translation norsk polarinstitutt, oslo). warren, c. r. 1991: teminal environment, topographic con trol and fluctuations of west greenland glaciers. boreas20, van der wateren, d. f. m. 1985: a model of glacial tectonics, applied to the ice-pushed ridges in the central netherlands. bull. geol. soc. denmark 34, 55-75. werner, a. 1988: holocene glaciation and climatic change on spitsbergen, svalbard. ph.d. thesis. department of geo logical sciences, university of colorado, usa. 2% pp. 1-15. por_004.fm polar research 26 (2007) 7 – 13 © 2007 the authors 7 blackwell publishing incmalden, usaporpolar research0800-03952007 blackwell publishing ltd? 2007261713original articles the distribution of snow accumulation on austfonnaa. taurisano et al. the distribution of snow accumulation across the austfonna ice cap, svalbard: direct measurements and modelling andrea taurisano, 1 thomas v. schuler, 2 jon ove hagen, 2 trond eiken, 2 even loe, 2 kjetil melvold 3 & jack kohler 1 1 norwegian polar institute, polar environmental centre, norway 2 deptartment of geosciences, university of oslo, box 1047, blindern, no-0316 oslo, norway 3 norwegian water resources and energy directorate, box 5091, majorstua, no-0301 oslo, norway abstract we present an analysis of the spatial variability in the snow accumulation on the austfonna ice cap in svalbard, norway, based on the results of field investigations conducted in the spring of 1999, 2004 and 2005. during the campaigns ground penetrating radar measurements at 500 and 800 mhz were collected along profiles, along with additional manual snow sounding and pit stratigraphy work. the analysis of the data reveals a consistent pattern in the spatial distribution of the snow accumulation over the ice-cap, and therefore enables the compilation of a multiple regression model of the snow distribution across the ice cap. once validated, the results of the model complement the information derived from direct measurements, with an accumulation index for every point on the ice cap, thus enhancing the accuracy of future mass balance studies and dynamic modelling of austfonna. as very few direct meteorological measurements are performed in the eastern part of svalbard, the accumulation measurements on the austfonna ice cap provide valuable integrated information about winter precipitation in this region. keywords snow accumulation; mass balance; gpr; modelling. centred at 79.7 ° n, 24.0 ° e, the austfonna ice cap stretches out over much of nordaustlandet, the northeastern island of the svalbard archipelago, and with an area of 8120 km 2 it is the largest ice cap in the european arctic. the ice cap has a maximum elevation of 809 m a.s.l., a thickness of up to ca. 560 m (dowdeswell et al. 1986) and a relatively simple geometry, characterized by one main dome feeding a number of drainage basins. there is evidence that the dynamic regime differs between individual basins, and some of them are known to be of the surge type (dowdeswell 1986). the scientific exploration of austfonna started with the first crossing by a. e. nordenskjold in 1873. new traverses were completed by the oxford expedition in 1924 (binney 1925), h. w. ahlmann in 1931 (ahlmann 1933) and v. schytt during the international geophysical year 1957/58 (schytt 1964). more recently, glaciological and geophysical investigations were carried out by j. a. dowdeswell in the 1980s (dowdeswell & drewry 1989). these included a radar-based mapping of the ice surface and bedrock topography, and the earliest ground-based measurements of mass balance and ice velocity. recently, airborne laser altimetry, first conducted in 1996 and repeated in 2002, indicated an elevation increase in the central parts of the ice cap and lowering towards the margins (bamber et al. 2004). although work has started to assess the contribution of surface mass balance (schuler et al. in press), there is still considerable uncertainty about the present state of balance of austfonna and how it may respond to climate change. in the mid 1980s deep ice cores were retrieved from austfonna by russian investigators (punning et al. 1986; zagorodnov & arkhipov 1990), and new cores from down to 118 and 288 m were obtained by japanese teams in 1998 and 1999, respectively (watanabe et al. 2000). during the same two years, 29 shallow cores were drilled by norwegian researchers to investigate the accumulation pattern on austfonna (melvold et al. 1999). furthermore, this work was complemented with a number of ground penetrating radar (gpr) profiles and provided a first insight to the spatial distribution of the accumulation (pinglot et al. 2001). the authors found a north-west– south-east gradient in the snow accumulation for the winter of 1998/99, which suggested that the northeastern location of austfonna in the svalbard archipelago is likely to make austfonna more directly influenced by correspondence andrea taurisano, multiconsult as, fiolvegen 13, 9016, tromsø, norway. email: andrea.taurisano@multiconsult.no doi:10.1111/j.1751-8369.2007.00004.x 8 polar research 26 (2007) 7 – 13 © 2007 the authors the distribution of snow accumulation on austfonna a. taurisano et al. atmospheric systems from the barents sea region than by westerly systems. this observation suggests that meteorological records from the automatic stations situated on spitsbergen are not representative of the weather conditions on the ice cap, and can not be reliably used as input data for either mass balance reconstructions or glaciological models. therefore, it is essential to collect information on the snow accumulation distribution and the recent temporal variability from the austfonna glacier itself. this is also relevant in light of the fact that still too little is known about the present mass balance of austfonna. the aim of this work is to present the results of groundbased measurements of snow accumulation repeated on austfonna in the spring of 1999, 2004 and 2005 by using a combination of gpr, direct snow sounding and snowpit work. a multiple regression model is also presented for the snow distribution across the ice cap. we develop a diagnostic model of snow distribution based on these data. hence we do not intend to make temporal predictions (e.g. future evolution), but do intend to achieve a spatially consistent (i.e. no gaps) description of our observations. data and methods gpr and global positioning system (gps) profiles were collected on austfonna, at the end of april 1999, 2004 and 2005 (fig. 1), in a time window during which the winter snow pack is believed to be of maximum thickness before the onset of melting. for the geophysical investigations, a ramac impulse radar (mal geoscience, mal , sweden) operating at 500 mhz was used in 1999, whereas an 800-mhz antenna was utilized in 2004 and 2005. in 1999, each radar file was collected in the form of 512 samples with a sampling frequency of 4865 mhz, giving a time window of 105 ns for each trace. in 2004 and 2005, the radar was operated with 1024 samples with a sampling frequency of 8099 mhz, and a corresponding time window of 126 ns. for each campaign, the radar control unit, a laptop, a gps receiver and a tripodmounted gps antenna were installed in a sledge pulled by a snowmobile, while the radar antenna was placed in a pulka sledge gliding about 2 m behind the first sledge. the radar was operated in time mode with a time interval of 0.5 s, which corresponds to ca. 2 m when driving at a speed of 4 m s − 1 . the gps mounted on the sledge, a javad positioning systems dual frequency gps (javad navigation systems, san jose, ca, usa) with glonass receiver (www.glonass-ianc.rsa.ru), was used as a rover for the kinematic survey of the profiles, whereas an analogous receiver collected static observations at the camp site on the glacier summit. all gps observations from this ȧ ȧ reference receiver were in turn referred to those collected at a fixed geodetic point situated on a hill ca. 45 km west of the summit. further details of this method are described by eiken et al. (1997). snow thickness profiles are obtained from the radar files by digitizing the reflector that corresponds to the surfaces of the previous summer, i.e. the snow–ice transition in the ablation area and the snow–firn interface in the accumulation area. these transitions are revealed on the radar profiles by the first continuous reflector, whereas occasional ice layers within the snow pack appear as shorter lower amplitude reflectors and are better detected when using the higher resolution 800-mhz antenna. the digitalization was performed manually, as the accuracy of the automatic picking routine is greatly affected by the dielectric constant contrast between the snow and the underlying firn or ice, and a number of other factors described by pinglot et al. (2001), the most important being the roughness of the interface and interferences from nearby reflectors. at some places the heterogeneous dielectric properties of the firn made it especially problematic to digitize the summer surface in the accumulation area. in these cases, it proved beneficial to calibrate the gpr profile using manual snow depth soundings, which were collected at 2-km intervals along the profiles. these were additionally backed up by digging pits down to the base of the winter snow pack. the gps measurements finally allowed us to geo-code both manual soundings and radar profiles. analysis and results over 250 km of radar profiles were collected both in 1999 and 2004, whereas bad weather limited the data collection in 2005 to only ca. 150 km of profiles. all profiles measured along the south-west–north-east and northwest–south-east transects were repeated with the spatial accuracy of a few metres typically allowed by gps navigation. the gpr measurements performed along the north–south traverse in 2004 and (partly) in 2005 do not overlap with the ones from 1999, but run roughly parallel ca. 2 km east of them. the reason for this is that the latest investigations were concentrated along two of the future cryosat orbit tracks, where airborne geophysical measurements were also being carried out as part of the international cryosat calibration and validation effort. the limited overlay of the measurements conducted in different campaigns influences the type of data analysis used. in fig. 2 we present snow thickness profiles derived from three years of radar investigations along the (a) north-west–south-east and (b) south-west–north-east transects on austfonna. a consistent east–west gradient a. taurisano et al. the distribution of snow accumulation on austfonna polar research 26 (2007) 7 – 13 © 2007 the authors 9 in snow accumulation is found, with snow depths on the east side of the ice cap being at least double the snow depths on the west side, as suggested by pinglot et al. (2001). the full datasets of snow thickness for the three years 1999, 2004 and 2005 are presented in fig. 3. intercomparison of the individual datasets shows a considerable year-to-year variability of snow thickness, with significantly less snow in 2004 than in the other two years (compare also fig. 2). closer inspection of the spatial distribution of the snow thickness data reveals an accumulation gradient from the highest values found in the south-east part of the ice cap to the considerably lower values found in the north-west (fig. 3). in all three years, snow accumulation in the south-east part was about three times larger than that in the north-west. this general pattern was recognized by schytt (1964) and more recently by pinglot et al. (2001), who used spatial interpolation techniques to investigate the snow distribution based on the 1999 dataset. however, the methodology used in their analysis describes snow thickness at each location only as a function of distance to the surrounding data points, and hence can be regarded as a data interpolator. here, instead, we aim to develop a parameterization of the snow distribution that can describe the accumulation pattern at every point of the ice cap. such a parameterization could be used in a model of the surface mass balance, requiring a spatially complete accumulation scheme that can be driven by external (e.g. meteorological) data. in previous studies, snow accumulation was often distributed over the domain using a linear lapse rate with elevation (e.g. schuler et al. 2002, 2005), an approach that is appropriate on valley glaciers. however, scatter plots of snow thickness data versus elevation across the austfonna ice cap (fig. 4a) exhibit two clearly separated branches, which shows that a single elevation gradient is not appropriate to describe the data. investigating the relationships between snow thickness and the other spatial coordinates reveals that the snow thickness is most closely correlated to the x coordinate (fig. 4b), whereas the relationship to the y coordinate (fig. 4c) shows a more complex pattern. in summary, the data reveals a pronounced south-east–north-west component in the snow distribution, with the east–west component being larger than the south–north component. additionally, an elevation gradient is superimposed on this trend. the bell-shaped distribution in fig. 4a suggests different linear elevation gradients for different expositions of the ice cap. we aim to describe this distribution by adopting a gradient in the horizontal plane with a vertical gradient superimposed on it. the same approach has been used previously by a~ algeirsdóttir et al. (2003) to parameterize the mass balance across the vatnajökull ice cap. the gradients in our snow distribution can thus be determined using a multiple regression approach that relates the snow thickness to all three spatial coordinates. this approach better describes the snow thickness at each location (fig. 4d). the functional relationship takes the form (1) where the terms x , y and z are the spatial coordinates (in metres), s denotes the snow thickness (in metres) s a a x a y a z= + + +0 1 2 3 figure 1 location map of nordaustlandet (inset map shows svalbard) showing the tracks of the profiles measured in 1999, 2004 and 2005 (thick lines). the thin lines indicate profiles measured in 1999 only, whereas the white dots mark manual soundings of the snow thickness. 10 polar research 26 (2007) 7 – 13 © 2007 the authors the distribution of snow accumulation on austfonna a. taurisano et al. and a 0 − a 3 are the coefficients determined using regression analysis. this procedure is performed by using the 1999 and 2004 data to train the model, and then using the 2005 data as an independent test dataset to evaluate the analysis. to take the considerable year-to-year variations in snow accumulation into account, snow thickness values need to be scaled before the regression coefficients are determined. we use the average thickness as a scale for the snow thickness such that the spatial average of the scaled values s ′ across the ice cap equals one ( ′ = 1). thus, local values represent proportions of the average accumulation that vary between individual years, but the year-to-year variation in the scaled values is removed. the values of a determined using the 1999 and 2004 datasets individually are listed in table 1. average values of a are used to describe the typical snow distribution, which is also evaluated s independently using the 2005 dataset (also presented in table 1). the correlations between the modelled and the observed values of snow thickness are high for the calibration, as well as for the validation datasets, yielding correlation coefficients larger than 0.8. an accumulation index map derived by this method is presented in fig. 3d and shows the spatial distribution of the scaled snow thickness. discussion and conclusions across austfonna the snow distribution is largely controlled by two factors: the distribution of precipitation and the redistribution of snow by wind drift. from theory, one would expect both mechanisms to be controlled by terrain characteristics such as slope, exposition and elevation, in addition to the prevailing wind direction and figure 2 snow thickness profiles along the (a) north-west–south-east and (b) south-west– north-east transects on austfonna. (a) (b) a. taurisano et al. the distribution of snow accumulation on austfonna polar research 26 (2007) 7 – 13 © 2007 the authors 11 figure 3 distribution of snow thickness measured along profiles in (a) 1999, (b) 2004 and (c) 2005; units are in metres. (d) accumulation map derived from these measurements; the values are dimensionless and scaled to the mean snow thickness. (a) (b) (c) (d) figure 4 scatter plots illustrating the relationships between (a) the measured snow thickness, s , and elevation, (b) s and the x coordinate and (c) s and the y coordinate. (d) correlation between the measured snow depths and the values provided by the multiple regression function. the plots show data from 2004. (a) (b) (c) (d) table 1 coefficients used to describe the snow distribution across the austfonna ice cap and correlation coefficient r between the modelled and the observed values along the radar transects. a 1 (m) a 2 ( − ) a 3 ( − ) a 4 ( − ) r 1999 86.2476 1.30 × 10 − 5 − 1.07 × 10 − 5 1.1 × 10 − 3 0.88 2004 52.9529 1.16 × 10 − 5 − 0.68 × 10 − 5 0.5 × 10 − 3 0.83 mean 69.6003 1.23 × 10 − 5 − 0.87 × 10 − 5 0.8 × 10 − 3 2005 (evaluation) — — — — 0.87 12 polar research 26 (2007) 7 – 13 © 2007 the authors the distribution of snow accumulation on austfonna a. taurisano et al. distance from the moisture source. the two latter effects are not specifically accounted for in our approach, so we implicitly assume that the direction and the strength of the moisture flux are constant. this assumption is not a severe oversimplification of reality because precipitation on nordaustlandet comes predominantly from the east (e.g. førland et al. 1997), and the major moisture source in that direction is the ice-free part of the barents sea. furthermore, relating snow thickness to coordinates instead of either slope or exposition requires that there is a close relationship between these terrain characteristics and position. ideally, on a hemisphere, the exposition and slope of each point are sufficiently determined by its position. the simple dome shape of the austfonna ice cap comes relatively close to this ideal, and this explains the success of our simple approach. analysing the spatial distribution of snow thickness across austfonna for the three years 1999, 2004 and 2005 revealed that there is considerable year-to-year variability, but that the accumulation pattern across the ice cap is constant. snow thickness along the radar profiles varied in all datasets from high values in the south-eastern parts of the ice cap to lower values in the north-western regions. this distribution has been successfully described using a linear regression model that uses the spatial coordinates as predictors. we have also investigated the distribution of the residuals between modelled and measured snow thickness and found that they are normally distributed, thereby indicating the validity of the linear regression model. in our simple model, we assume two different gradients for snow distribution: one vertical gradient with elevation and one horizontal gradient in the x − y plane. these can be represented as linear functions of the three cartesian coordinates. using eq. 1, we implicitly assume that the effects of the predicting variables ( x , y and z ) on the dependent term ( s ) are additive and do not interact. this condition might seem restrictive. however, in additional experiments we have investigated the effects of including interaction terms in a stepwise procedure and concluded that these are negligible. unlike previous interpolations of snow data, our approach enabled the calculation of an accumulation index for every point on the ice cap. this will be of great benefit in future work focusing on the modelling of the surface mass balance of austfonna, something which requires spatially complete accumulation information possibly controlled by external meteorological data. a further aspect of possible interest to the climate community is that the distribution of accumulation across austfonna may be regarded as an integrative proxy for the distribution of winter precipitation in a region where meteorological observations are otherwise scarce. acknowledgements this work was carried out with support from the cryosat calibration and validation project (esa contract no. c90118), from spice, space borne measurements of arctic glaciers and implications for sea level (eu contract no. evk2-2001-00262) and from integral, interferometric evaluation of glacier rheology and alterations (eu contract no. sst3-ct-2003-502845). the authors wish to thank the two anonymous reviewers, whose comments improved this article. references a~ algeirsdóttir g., gudmundsson g.h. & björnsson h. 2003. a regression model for the mass-balance distribution of the vatnajökull ice cap, iceland. annals of glaciology 37 , 189–193. ahlmann h.w. 1933. the inland cartography of north-east land. geografiska annaler 15 , 47–68. bamber j.l., krabill w., raper v. & dowdeswell j.a. 2004. anomalous recent growth of part of a large arctic ice cap: austfonna, svalbard. geophysical research letters 31 , doi: 10.1029/2004gl019667. binney f.g. 1925. the oxford university arctic expedition 1924. the geographical journal 66 , 9–40. dowdeswell j.a. 1986. drainage-basin characteristics of nordaustlandet ice caps, svalbard. journal of glaciology 32 , 31– 38. dowdeswell j.a. & drewry d.j. 1989. the dynamics of austfonna, nordaustlandet, svalbard: surface velocities, mass balance, and subglacial melt water. annals of glaciology 12 , 37–45. dowdeswell j.a., drewry d.j., cooper a.p.r., gorman m.r., liestøl o. & orheim o. 1986. digital mapping of the nordaustlandet ice caps from airborne geophysical investigations. annals of glaciology 8 , 51–58. eiken t., hagen j.o. & melvold k. 1997. kinematic gps survey of geometry changes on svalbard glaciers. annals of glaciology 24 , 157–163. førland e.j., hanssen-bauer i. & nordli p.ø. 1997. climate statistics & longterm series of temperature and precipitation at svalbard and jan mayen. dnmi report 21/1997 klima . blindern: norwegian meteorological institute. melvold k., hagen j.o., eiken t. & pinglot j.f. 1999. report from fieldwork on the austfonna ice cap, svalbard, 7th april–7th may 1999 . oslo: department of physical geography, university of oslo. (second year report of e.c. contract no. env4ct97–0490.) pinglot j.f., hagen j.o., melvold k., eiken t. & vincent c. 2001. a mean net accumulation pattern derived from radioactive layers and radar soundings on austfonna, nordaustlandet, svalbard. journal of glaciology 47 (159), 555–566. punning y.-m.k., martma t.a., tyugu k.e., vaykmyae r.a., pourchet m. & pinglot f. 1986. stratification in an ice core from vestfonna, nordaustlandet. polar geography and geology 10 , 39–43 (translated from materialy glyatsiologicheskikh issledovanii 52 , 202–205). a. taurisano et al. the distribution of snow accumulation on austfonna polar research 26 (2007) 7 – 13 © 2007 the authors 13 schuler t., fischer u.h., sterr r., hock r. & gudmundsson g.h. 2002. comparison of modelled water input and measured discharge prior to a release event: unteraargletscher, bernese alps, switzerland. nordic hydrology 33 , 27–46. schuler t.v., hock r., jackson m., elvehøy h., braun m., brown i. & hagen j.o. 2005. distributed mass balance and climate sensitivity modelling of engabreen, norway. annals of glaciology 42 , 395–401. schuler t.v., loe e., taurisano a., eiken t., hagen j.o. & kohler j. in press. a calibrated surface mass balance model for the austfonna ice cap, svalbard, annals of glaciology 46 . schytt v. 1964. scientific results of the swedish glaciological expedition to nordaustlandet, spitsbergen, 1957 and 1958. geografiska annaler 46 , 243–281. watanabe o., kamiyama k., kameda t., takahashi s. & isaksson e. 2000. activities of the japanese arctic glaciological expedition in 1998 (jage 1998). bulletin of glaciological research 17, 31–35. zagorodnov v. & arkhipov s. 1990. studies of structure, composition and temperature regime of sheet glaciers of svalbard and severnaya zemlya: methods and outcomes. bulletin of glaciological research 8, 19–28. ichnodiversity and bathymetric range of microbioerosion traces in polar barnacles of svalbard research article ichnodiversity and bathymetric range of microbioerosion traces in polar barnacles of svalbard neele meyer,1,2 max wisshak2 & andré freiwald1,2 1 faculty of geosciences, university of bremen, bremen, germany 2 senckenberg am meer, marine research department, wilhelmshaven, germany abstract this first comprehensive investigation of microbioerosion traces in polar barnacles addresses two bathymetrical transects from the intertidal down to subtidal water depths in two different carbonate factories in the svalbard archipelago: the bay mosselbukta and the ocean bank bjørnøy-banken. scanning electron microscopy of epoxy resin casts of barnacle shells yielded 20 different microendolithic bioerosion traces, probably produced by cyanobacteria (three), chlorophytes (two), rhodophytes (one), sponges (one), foraminifera (three), fungi (nine) and bacteria (one). the lowest ichnodiversity in both locations was observed in the shallow euphotic zone and is likely a result of strong temperature fluctuations, extreme seasonality of light levels and episodic sea-ice cover. at 25–150 m water depth, the ichnodiversity remains relatively constant (9–13 ichnospecies), albeit with differing ichnospecies composition, generally dominated by borings from chlorophytes and fungi. ichnotaxa at mosselbukta and bjørnøy-banken were similar in numbers but differed in abundance and slightly also in ichnospecies composition. statistical tests indicate that water depth (affecting the availability of light) is the most significant driver for the development of different microbioerosion trace assemblages across the bathymetrical transects. in contrast, no significant differences in ichnodisparity were found, indicating a comparable suite of architectural designs of the micro-borings throughout bathymetry and location. the comparison of our results with literature data confirms a decrease in ichnodiversity from lower to higher latitudes, although targeted bioerosion analyses from other polar environments are needed to gain a more complete picture of the role of bioerosion in polar carbonate factories. keywords bioerosion; ichnotaxonomy; ichnodisparity; arctic; mosselbukta; bjørnøy-banken abbreviations anosim: analysis of similarities nmds: non-metric multidimensional scaling par: photosynthetically active radiation simprof: similarity profile analysis sem: scanning electron microscopy citation: polar research 2020, 39, 3766, http://dx.doi.org/10.33265/polar.v39.3766 copyright: polar research 2020. © 2020 n. meyer et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 14 september 2020 competing interests and funding: the authors report no conflict of interest. this work was funded by the german research foundation (dfg) under grant wi 3754/3-1 and the rv maria s. merian msm55 cruise that provided the studied samples was funded by the dfg in concert with the leitstelle deutsche forschungsschiffe. open access fees for this publication were funded by the university of bremen, germany. correspondence to: neele meyer, senckenberg am meer, marine research department, südstrand 40, de-26382 wilhelmshaven, germany. e-mail: neele.meyer@senckenberg.de introduction bioerosion is the degradation of hard substrates by biological means (neumann 1966) and plays an important ecological and biosedimentological role from low to high latitudes. the process is divided into internal and external bioerosion (bromley 2004). internal bioeroders excavate the substrate for shelter, whilst external ones bioerode by means of grazing or fixation (bromley 2004; tribollet et al. 2011). internal bioerosion is further subdivided into micro(e.g., by cyanobacteria, chlorophytes, fungi) and macrobioerosion (e.g., by polychaetes, bivalves, sponges), distinguished by the trace dimensions (smaller or larger than 1 mm) they leave behind in the substrate (wisshak 2012). these bioerosion traces and trace fossils are taxonomically treated as ichnotaxa. they are commonly analysed via sem of epoxy casts, prepared by applying the vacuum cast-embedding technique (wisshak 2006, 2012). although bioerosion is a key process on a global scale, bioerosion research has so far mainly focussed on subtropical and tropical environments, there particularly on coral reefs, and therefore considering primarily the photic zone. high latitudes have received much less attention (for a review, see wisshak 2006), and the north atlantic is represented, inter alia, by studies off the scottish coast (akpan & farrow 1985; glaub et al. 2002), norway (bromley & hanken 1981; schmidt & freiwald 1993; glaub et al. 2002) and sweden (wisshak et al. 2005). spitsbergen was, for instance, studied with a focus on polychaete bioerosion (hanken et al. 2012) and the canadian arctic with a focus on macroborings (aitken & risk 1988). a comprehensive investigation of bioerosion traces, considering a broader bathymetrical range and including the different types of bioerosion traces, is lacking for polar environments and would help to better understand the role of bioerosion in polar carbonate factories. therefore, this study establishes a comprehensive catalogue of microbioerosion traces in two high-latitude carbonate depositional environments in the svalbard archipelago at 74° and 80° northern latitude. barnacles were the chosen substrate because they are sessile calcifiers that are most likely to bear bioerosion traces from the corresponding water depth when sampled alive. they occur from the intertidal down to aphotic water depths in svalbard, allowing an establishment of bathymetric transects extending from the shore to 125 m water depth at mosselbukta (northern spitsbergen) and east of the island of bjørnøya (southernmost svalbard). we provide a statistical ichnodiversity analysis to compare these two locations. this approach allows us to evaluate the ichnodiversity variability of bioerosion within the arctic environment and at different water depths. in addition, we apply the ichnodisparity concept to determine the diversity of architectural designs in bioerosion traces and, therefore, the established behavioural patterns of microbioeroders (buatois et al. 2017). finally, we assess our observations in the context of a low to high latitudinal gradient. methods study sites svalbard (fig. 1a) is in an arctic environment on the north-western margin of the barents shelf, approximately 650 km north of the norwegian mainland. in 2016, mosselbukta, our first study site, near the northern tip of spitsbergen (fig. 1b), was covered by drift ice for 14 days, whereas bjørnøy-banken, the second study site in the south (fig. 1c), was covered by very open to open drift ice at the end of march for about a week (fig. 2; norwegian meteorological institute 2019). fig. 1 map of the (a) svalbard archipelago and bathymetry for (b) mosselbukta and (c) bjørnøy-banken (east of bjørnøya), including stations for sample collection and applied gear of recovery (station metadata are listed in table 1). fig. 2 schematic overview of the seasonality at mosselbukta. (salinity and temperature data for 2006 simplified after wisshak et al. [2019]. phytoplankton bloom and subsequent summer/autumn production based on zenkevitch [1963]. polar night and day data retrieved from the noaa global monitoring laboratory [2020]. ice data for 2016 obtained via the ice chart archive of the norwegian meteorological institute [2019].) mosselbukta is influenced by 123 days of polar night (data for 2016 obtained from noaa global monitoring laboratory [2020]; fig. 2). the local carbonate factory is characterized by rhodoliths beds, which cover up to 100% of the seafloor in some areas (teichert et al. 2014). bjørnøy-banken is a shallow (20–150 m) shelf platform to the east of bjørnøya (bear island), where extensive biogenic carbonate sediments accumulate in a strong hydrodynamic regime (henrich et al. 1997; wisshak et al. 2017; wisshak et al. 2019), and experiences 88 days of polar night (data for 2016 obtained from noaa global monitoring laboratory [2020]). the temperature in 2006 in mosselbukta at 46 m water depth ranged from -2 °c to 6.3 °c, whereas salinity remained relatively constant from 33.2 to 35.4 (wisshak et al. 2019). the boundary between the euphotic and dysphotic zones in summer was between 20 and 25 m water depth at mosselbukta, whilst the base of the dysphotic zone was located at ca. 64 m (teichert et al. 2014). neither annual temperature or salinity data nor par-measurements for the determination of photic zones are available for bjørnøy-banken. however, par measurements via lander deployments at mosselbukta and bjørnøy-banken in the summer of 2016 showed higher (tidal) current-induced turbidity and lower light levels at bjørnøy-banken (wisshak et al. 2019), suggesting that the photic zonation is a bit more condensed compared with mosselbukta. a detailed environmental characterization for the two study sites is provided by wisshak et al. (2019). table 1 list of analysed samples, including water depth, station number, coordinates, gear and number of samples obtained during the msm55 cruise. for the jago and the rock dredge, the coordinates indicate the location of the vessel at the start of the survey. station locations are shown in fig. 1. depth (m) station location gear no. of samples mosselbukta  0 msm55 437-1 79°54.44′ n 15°58.95′ e shore excursion 4  0 msm55 437-2 79°53.33′ n 16°02.95′ e shore excursion 5  0 msm55 451-1 79°52.29′ n 15°41.57′ e shore excursion 7  0–20 msm55 447-1 79°55.94′ n 15°51.47′ e jago dives 10  0–20 msm55 437-1 79°54.44′ n 15°58.95′ e shore excursion 9  25 msm55 468-1 79°54.78′ n 15°52.65′ e dredge 4  25 msm55 468-2 79°54.75′ n 15°52.21′ e dredge 4  50 msm55 443-1 79°53.22′ n 15° 45.88′ e dredge 4  50 msm55 443-2 79°53.44′ n 15°46.02′ e dredge 4  75 msm55 456-1 79°53.25′ n 15°44.17′ e dredge 4  75 msm55 456-2 79°53.48′ n 15°44.40′ e dredge 4  100 msm55 418-1 79°53.56′ n 15°42.76′ e dredge 4  125 msm55 480-1 79°54.72′ n 15°43.33′ e dredge 4  125 msm55 480-2 79°54.44′ n 15°43.83′ e dredge 4 bjørnøy-banken  0–20 msm55 507-2 74°23.25′ n 19°10.33′ e shore excursion 8  21 msm55 501-1 74°22.48′ n 19°11.57′ e shipek grab 6  38 msm55 489-1 74°22.62′ n 19°21.42′ e jago dives 8  50 msm55 484-1 74°22.98′ n 19°28.35′ e jago dives 4  50 msm55 488-3 74°22.50′ n 19°27.80′ e dredge 4  76 msm55 516-1 74°22.50′ n 19°51.55′ e jago dives 8  95 msm55 522-1 74°22.19′ n 19°54.55′ e jago dives 8 sample collection during the msm55 cruise with the rv maria s. merian in the summer of 2016 (wisshak et al. 2017), we collected live balanids (barnacles) of the species balanus balanus (linnaeus, 1758) with a rock dredge, a shipek grab and the research submersible jago along bathymetrical transects, growing on boulders or chlamys islandica (müller, 1776). the collection was complemented by a few balanus crenatus bruguière, 1789 sampled in the intertidal zone during shore excursions. both species live in association down to 60 m water depth, although b. crenatus is primarily a sublittoral species, whereas b. balanus prefers deeper waters (e.g., barnes & powell 1953; barnes & barnes 1954; luther 1987). in accordance with the approach by barnes & barnes (1954), our analysed specimens of b. balanus were perennial and at least four to six years old, as some of the detached balanids had a rostro-carinal diameter of 30–40 mm (consistent with observations of balanus balanoides in spitsbergen by feyling-hanssen [1953] and luther [1987]). balanus crenatus specimens were likely younger, as they were analysed to have a lifespan of one to two years (barnes & powell 1953). balanids are suitable substrates for bioerosion studies (e.g., glaub et al. 2002; feussner et al. 2004) and are abundant in polar waters around svalbard at all water depths (fig. 3). balanids were collected in roughly 25 m depth intervals, spanning the intertidal to 95 and 125 m water depth at bjørnøy-banken and mosselbukta, respectively (table 1, fig. 1b, c). fig. 3 the seafloor in svalbard carbonate factories, illustrating the abundance of balanids at (a) the rhodolith beds in mosselbukta (ca. 45 m water depth; submersible jago in the background; photo courtesy of solvin zankl) and at (b) the carbonate platform at bjørnøy-banken (ca. 100 m water depth). sample preparation and analysis immediately after the recovery, balanids were soaked in freshwater to remove the salt and then dried at 50 °c. prior to the vacuum cast-embedding technique (wisshak 2006, 2012), organic material was removed with sodium hypochlorite (customary cleaning agent); afterwards, the specimens were rinsed with deionized water and dried at 30 °c for 12 hrs. to enhance the impregnation with r&g “water clear” epoxy resin, the balanids were placed in a citovac (struers) vacuum chamber. once the resin cured, the embedded samples were cut with a rock saw and treated with ca. 5% hydrochloric acid to remove the carbonate. one hundred seventeen casts were glued onto stubs and sputter-coated with gold (cressington sputter coater 108) for sem investigation using a tescan vega3 xmu scanning electron microscope, using the secondary electron detector at 20 kv. bioerosion traces were identified at ichnospecies level where applicable and otherwise treated in open nomenclature or addressed by informal names. a semi-quantitative analysis of the identified bioerosion traces was performed because actual quantification is unfeasible for bioerosion traces. there is a wide range of sizes, traces may superimpose each other, and whilst individual borings can be easily recognized in some of the ichnotaxa, this is impossible for larger and intergrown networks. we classified each ichnotaxon per sample into one of four abundance classes: absent (0); very rare, only one or very few specimens (1); rare, few specimens (2); common, many specimens but not dominant (3); very common or dominant (4). these were then averaged by the number of investigated samples per water depth (after wisshak et al. 2011). statistical ichnodiversity analyses to evaluate the ichnodiversity, we used the r version 3.5.2 software (r core team 2018) to perform multivariate normality tests (mardia and royston) using the mvn package (korkmaz et al. 2014). prior to the following tests, we computed a bray–curtis dissimilarity matrix using the vegan r package (oksanen et al. 2018) from the untransformed ordinal data, which is a common practice for an anosim (hammer & harper 2008; greenacre & primicerio 2013) and can be used for relative abundance data (greenacre & primicerio 2013). for the non-parametric anosim test, we used vegan (999 permutations) to statisically test that there was no significant difference between two or more groups (null hypothesis). the output is the p value and an r value between –1 and 1; a number close to 0 means that there is no difference between sites. the vegan package was also utilized for the nmds plots to visualize similarities in two dimensions (hammer & harper 2008). the clustsig package (whitaker & christman 2014) with the cluster method “average” was used for the cluster analyses with simprof to determine and visualize the number of significant clusters. the biodiversity indices margalef’s richness index d, simpson index of dominance λ and diversity 1−λ, shannon index h′(loge) and pielou’s evenness j′ were calculated using primer 6, version 6.1.16, software (plymouth marine laboratory). whilst these indices are usually based on counts of specimens (hammer & harper 2008), we used our ordinal data and transformed the abundance classes in different orders of magnitude (4 was transformed to 1000; 3 to 100; 2 to 10; 1 kept as 1) to obtain relative abundances, following the approach introduced by wisshak et al. (2011). results ichnodiversity of microborings a total of 20 different microbioerosion traces were detected: 18 ichnotaxa in 71 samples from mosselbukta and 16 traces in 46 samples from bjørnøy-banken. four traces were unique to mosselbukta and two to bjørnøy-banken. all ichnotaxa are dwelling traces in the ethological class “domichnia” (after vallon et al. 2016). traces were grouped in accordance with the inferred or assumed type of microendolithic trace-makers (table 2); these include cyanobacteria (three traces), chlorophytes (two), rhodophytes (one), sponges (one), foraminifera (three), fungi (nine) and bacteria (one). table 2 list of ichnotaxa recorded from mosselbukta and bjørnøy-banken, the inferred or assumed (in parentheses) microendoliths based on the original interpretation of the ichnotaxon authority and the relevant figure number. microendolith ichnotaxa mosselbukta bjørnøy-banken fig. (cyanobacteria) “fascichnus isp. i” x 4a (cyanobacteria) “fascichnus isp. ii” x 4b (cyanobacteria) planobola cf. microgota schmidt, 1992 x x 4c chlorophytes cavernula pediculata radtke, 1991 x 4d chlorophytes ichnoreticulina elegans (radtke, 1991) x x 4e–g rhodophytes conchocelichnus seilacheri radtke et al., 2016 x x 4g–i (sponges) entobia mikra wisshak, 2008 x x 4j foraminifera nododendrina europaea (fischer, 1875) x x 4k, l (foraminifera) pyrodendrina arctica wisshak, 2017 x x 6e, f (foraminifera) pyrodendrina villosa wisshak, 2017 x x 6g (fungi) flagrichnus baiulus wisshak & porter, 2006 x x 5a, b (fungi) flagrichnus cf. baiulus wisshak & porter, 2006 x x 5c, d (fungi) flagrichnus cf. profundus wisshak & porter, 2006 x x 5e, f (fungi) orthogonum-form 1 sensu wisshak et al., 2005 x 6a (fungi) orthogonum lineare glaub, 1994 x x 6b (fungi) orthogonum tubulare radtke, 1991 x x 6c (fungi) orthogonum giganteum glaub, 1994 x 6d fungi saccomorpha clava radtke, 1991 x 5g (fungi) saccomorpha guttulata wisshak et al., 2018 x x 5h, i bacteria scolecia serrata radtke, 1991 x x 6h, i composition of ichnotaxa varied slightly between location and water depth and in abundance (table 3). in the shallow euphotic zone, mainly microborings by cyanobacteria (fascichnus ichnospecies), chlorophytes (e.g., cavernula pediculata) and rhodophytes (conchocelichnus seilacheri) were recorded. traces of unknown organotrophic producers such as foraminifera or fungi (e.g., pyrodendrina arctica or flagrichnus ichnospecies) were rare. the deep euphotic to dysphotic zone was densely colonized and had the highest ichnodiversity, with ichnoreticulina elegans as the dominant ichnotaxon, followed by flagrichnus isp. and c. seilacheri. the aphotic zone was characterized by a high abundance of inferred or assumed fungal microborings (e.g., saccomorpha guttulata) and a high ichnodiversity (table 3). table 3 results of semi-quantitative analysis of microbioerosion traces at mosselbukta and bjørnøy-banken. abundances are categorized as very common (++), common (+), rare (-) and very rare (--). ichnotaxon depth (m) total range (m) mosselbukta bjørnøy-banken 0a 0–20a 25b 50b 75b 100c 125c 0–20a 20a 38b 50b 75b 100c “f. isp. i” - 0 “f. isp. ii” - 38 p. cf. microgota schmidt, 1992 -- - 0–38 c. pediculata radtke, 1991 - 0 i. elegans (radtke, 1991) ++ ++ ++ - + -- 0–75 c. seilacheri radtke et al., 2016 + + + 0–50 e. mikra wisshak, 2008 -+ + -50–125 n. europaea (fischer, 1875) --- -+ 0–125 p. arctica wisshak, 2017 ---- 25–125 p. villosa wisshak, 2017 - -----0–125 f. baiulus wisshak & porter, 2006 ----+ + ---+ + 0–125 f. cf. baiulus wisshak & porter, 2006 - - ----0–100 f. cf. profundus wisshak & porter, 2006 -- -- ---0–100 o.-form 1 sensu wisshak et al., 2005 ----38–100 o. lineare glaub, 1994 -- ----38–125 o. tubulare radtke, 1991 --+ + ----25–125 o. giganteum glaub, 1994 - -- 0–125 s. guttulata wisshak et al., 2018 --+ --25–125 s. clava radtke, 1991 - 100 s. serrata radtke, 1991 ---+ -- 0–125 number of traces 6 10 9 11 11 12 10 8 5 13 12 12 11 svalbard 0 0–20 25 38 50 75 100 125 number of traces 6 11 9 13 14 13 14 10 aeuphotic conditions. bdysphotic conditions. caphotic conditions. description of some microborings in the following, we elaborate on the morphological characters of microborings whose morphology differs from the original diagnoses of the respective ichnotaxa. a few traces are described here in informal names, indicated by quotation marks. abundance and quantification of all observed microborings are outlined in table 3. “ fascichnus isp. i”. it has 100-µm-long, uniformly thick tunnels with a diameter of 10–12 µm, occasionally bifurcating with a 90° angle. the trace shows a somewhat radiating appearance of the tunnels collapsed to the surface of the cast. although the boring was too rare to provide a lot of details, we assumed a cyanobacterium as producer (fig. 4a). fig. 4 microborings inferred or assumed produced by (a)–(c) cyanobacteria, (d)–(g) chlorophytes, (g)–(i) rhodophytes, (j) sponges and (k)–(l) foraminiferans. (a) “fascichnus isp. i” from the intertidal at mosselbukta. (b) “fascichnus isp. ii” from 38 m water depth at bjørnøy-banken. (c) planobola cf. microgota from 0 to 20 m water depth at mosselbukta. (d) cavernula pediculata from the intertidal at mosselbukta. (e) overview and (f) close-up of ichnoreticulina elegans from 50 m water depth at mosselbukta. (g) ichnoreticulina elegans associated with conchocelichnus seilacheri (white arrows) from 50 m water depth at bjørnøy-banken. (h) conchocelichnus seilacheri from 0 to 20 m water depth at mosselbukta. (i) conchocelichnus seilacheri from 50 m water depth at bjørnøy-banken with prominent swellings. (j) entobia mikra from 75 m water depth at mosselbukta. (k) nododendrina europaea from 100 m water depth at mosselbukta and a small entobia mikra to the left. (l) nododendrina europaea from 95 m water depth at bjørnøy-banken with prominent long whips. “ fascichnus isp. ii”. this trace grows from swelling with a 10 µm diameter into a segmented and rarely twisted string with a maximum length of 75 µm (fig. 4b). planobola cf. microgota schmidt, 1992. this spheroid to bulbous boring has similarities in size to p. microgota but lacks a latitudinal contact to the substrate surface via vertical tubules. because further lack of characteristics prevented an assignment to a specific ichnospecies, we listed this ichnotaxon as p. cf. microgota (fig. 4c). conchocelichnus seilacheri radtke et al., 2016. conchocelichnus seilacheri has a high morphological variability. branchings are either wide, irregular and pancake‐like with a diameter of 3–14 µm or marked with almost perfectly shaped spherical swellings of up to 16 µm. the upright filament bushes of c. seilacheri have similarities to fascichnus frutex (radtke, 1991; fig. 4g–i), complicating distinction of the two ichnospecies. nododendrina europaea (fischer, 1875). nododendrina europaea has occasionally thick galleries of up to 100 µm in diameter and merging of single branches to a large plexus. at the bjørnøy-banken, striking long whips, originating from and around the single main chamber, were rarely observed (fig. 4k, l). flagrichnus cf. baiulus wisshak & porter, 2006. flagrichnus cf. baiulus appears to lack the diagnostic long, thin, filamentous tube. instead, the boring features thin filaments in the circumference. typical sack‐shaped cavities were occasionally connected with tunnels about 10 µm in length. in a few bjørnøy-banken samples, some of the traces show a rosette similar to the cretaceous ichnogenus dendrina quenstedt, 1849, but they are much smaller in dimension (fig. 5d). the unknown trace-maker may be identified based on tribollet et al. (2011): their figure 4b shows a fungus, whose morphology is similar to f. cf. baiulus (fig. 5c, d). fig. 5 microborings inferred or assumed by fungi. (a) close-up of flagrichnus baiulus from 75 m water depth at bjørnøy-banken. (b) initial flagrichnus baiulus from the intertidal at mosselbukta. (c) flagrichnus cf. baiulus from the intertidal at mosselbukta and (d) forming a rosette as observed in the intertidal at bjørnøy-banken. (e) flagrichnus cf. profundus from 50 m water depth at bjørnøy-banken and from (f) 100 m water depth at mosselbukta. (g) saccomorpha clava from 100 m water depth at mosselbukta. (h) overview of saccomorpha guttulata from 95 m water depth at bjørnøy-banken. (i) saccomorpha guttulata from 75 m water depth at bjørnøy-banken. flagrichnus cf. profundus wisshak & porter, 2006. this trace gradually tapers towards the end instead of a diagnosed basal‐swelling leading to a deeply penetrating gallery, as described for f. profundus. the microsculpture is uneven and it does not penetrate as deep (fig. 5e, f). “ orthogonum -form 1” sensu wisshak et al, 2005. this form comprises galleries 3–5 µm in diameter that run closely parallel to the substrate in a wavy manner for a few millimetres (fig. 6a). fig. 6 microborings produced by yet unknown organotrophic producers. (a) “orthogonum-form 1” from 95 m water depth at bjørnøy-banken. (b) orthogonum lineare from 100 m water depth at mosselbukta. (c) orthogonum tubulare from 100 m water depth at mosselbukta. (d) orthogonum giganteum from 100 m water depth at mosselbukta. (e) a large pyrodendrina arctica from 95 m water depth at bjørnøy-banken and (f) in angular view from 95 m water depth at bjørnøy-banken. (g) pyrodendrina villosa from 95 m water depth at bjørnøy-banken. (h) close-up of scolecia serrata from 75 m water depth at mosselbukta and (i) an overview from 50 m water depth at bjørnøy-banken. statistics of ichnodiversity and ichnodisparity mardia’s and royston’s multivariate normality tests resulted in p < 0.05 for ichnodiversity and multivariate normality was therefore rejected. an anosim to test for significant differences between locations resulted in r = 0.10 and a significance level of 0.15% (not significant). a second anosim to test the factor “water depth” (the light regime being the principal underlying factor) resulted in r = 0.80 and a significance level of 0.002% (significant). an nmds plot based on the bray–curtis similarity measure with the factor “location” showed that the microbioerosion trace assemblages in greater water depths cluster and were therefore similar to one another, whilst the shallow euphotic samples were outliers, reflecting dissimilarity (fig. 7a). a cluster analysis with simprof was computed to determine the number of significant clusters, which are four (fig. 7c). fig. 7 non-metric multidimensional scaling plots for the (a) ichnodiversity and (b) ichnodisparity at both study sites (data transformed with square root) and respective results of the cluster analyses with (c) and (d) similarity profile. for (c) ichnodiversity, the clustering correlates to four photic zones, shallow and deep euphotic, dysphotic, and aphotic, whereas (d) ichnodisparity, in contrast, shows a slightly less conclusive clustering in three photic zones. for the ichnodisparity analysis, each of the documented ichnogenera was assigned to one out of nine different groups (table 4), following the categories of architectural designs in trace fossils established by buatois et al. (2017). table 4 ichnogenera categorized into nine different ichnodisparity groups, according to buatois et al. (2017). architectural designs ichnogenera no. of ichnospecies 59—cylindrical vertical to oblique borings flagrichnus 3 64—globular to spherical borings planobola 1 66—clavate-shaped borings cavernula 1 68—branched tubular borings ichnoreticulina, scolecia, conchocelichnus a 3 69—non-camerate network borings orthogonum 4 70—camerate network borings saccomorpha 2 71—non-camerate boxwork borings entobia 1 74—radial borings fascichnus 2 75—dendritic and rosetted borings nododendrina, pyrodendrina 3 aconchocelichnus was not yet considered by buatois et al. (2017) and is herein categorized as a branched tubular boring (group 68). for the ichnodisparity analysis, mardia’s and royston’s multivariate normality tests resulted in p < 0.05, so multivariate normality was rejected. an anosim with the factor “location” computed r = 0.09 and a significance level of 0.18% (not significant), whilst the factor “water depth” resulted in r = −0.09 and a significance level of 0.62% (not significant). an nmds plot based on the bray–curtis similarity measure (fig. 7b) indicated that architectural designs are similar in greater water depths, whereas the shallowest stations are dissimilar. the simprof cluster analysis (fig. 7d) resulted in two to three main clusters: mo_0 was fairly excluded from the rest, whereas the other two clusters split into several smaller ones (roughly corresponding to the photic zones), including a mix of samples from the different water depths and sites (fig. 7d). indices of ichnodiversity and ichnodisparity according to the ichnodiversity indices, samples from deep euphotic water depths were dominated by single ichnotaxa (λ close to 1, i. elegans) and have therefore a low diversity (1-λ′ and h′(loge) close to 0) and a general unevenness (j′ close to 0). samples from dysphotic water depths had almost equally common ichnotaxa (λ close to 0), with high diversity (1-λ′ and h′(loge) close to 1 and higher, respectively) and high evenness (j′ close to 1). this pattern is more pronounced in mosselbukta (table 5, fig. 8a, b, d, e). table 5 diversity indices for ichnodiversity and ichnodisparity of microborings at mosselbukta and bjørnøy-banken, comprising ichnospecies richness s, margalef’s richness index d, simpson index of dominance λ and diversity 1-λ′, shannon index h′(loge) and pielou’s evenness j′. samplea ichnospecies richness, s margalef’s richness index, d simpson index of dominance, λ simpson index of diversity, 1-λ′ shannon index, h′(loge) pielou’s evenness, j′ ichnodiversity  mo_0 6 1.85 0.47 0.57 1.17 0.65  mo_0–20 10 1.30 0.97 0.03 0.12 0.05  mo_25 9 1.14 0.82 0.18 0.35 0.16  mo_50 11 1.44 0.93 0.07 0.22 0.09  mo_75 11 1.70 0.23 0.77 1.69 0.71  mo_100 12 1.80 0.20 0.80 1.80 0.72  mo_125 10 1.79 0.44 0.56 1.30 0.56  bj_0–20 8 1.31 0.47 0.53 0.86 0.41  bj_20 5 0.85 0.79 0.21 0.45 0.28  bj_38 13 3.08 0.17 0.85 2.01 0.78  bj_50 12 2.84 0.18 0.84 1.95 0.79  bj_75 12 2.20 0.48 0.52 1.23 0.50  bj_100 11 1.82 0.34 0.66 1.37 0.57 ichnodisparity  mo_0 5 2.49 0.20 1.00 1.61 1.00  mo_0–20 6 1.07 0.91 0.09 0.27 0.15  mo_25 5 0.85 0.79 0.21 0.45 0.28  mo_50 6 1.06 0.78 0.22 0.49 0.28  mo_75 6 1.02 0.59 0.41 0.87 0.49  mo_100 6 1.01 0.52 0.48 1.03 0.57  mo_125 6 1.57 0.35 0.67 1.26 0.70  bj_0–20 4 1.17 0.61 0.42 0.79 0.57  bj_20 4 1.17 0.61 0.42 0.79 0.57  bj_38 7 1.86 0.32 0.70 1.34 0.70  bj_50 5 1.52 0.53 0.51 0.99 0.62  bj_75 5 1.28 0.38 0.64 1.13 0.70  bj_100 5 0.85 0.79 0.21 0.45 0.28 amo refers to mosselbukta and bj refers to bjørnøy-banken. the numbers are water depths. fig. 8 assessment of diversity indices for (b) and (e) ichnodiversity and (c) and (f) ichnodisparity across the bathymetrical transect (a)–(c) at mosselbukta and (d)–(f) at bjørnøy-banken. salinity, temperature and density data (wisshak et al. 2017) were plotted with light intensities expressed as percent of the surface illumination in the logarithmic plots shown in (a) and (d) (light intensity data from teichert et al. 2014). as no light intensity data were available for (d) bjørnøy-banken, the photic zonation in mosselbukta is used as an approximation. ichnodiversity indices for the ichnodisparity concept demonstrate that svalbard samples from the deep euphotic stations were marked by a single dominant group of architectural designs (λ close to 1, branched tubular borings), as were the samples from 100 m water depth at bjørnøy-banken (dendritic and rosetted borings). those sites had also a low diversity (1-λ′ close to 0) and unevenness (j′ close to 0). the 0-m site at mosselbukta and 20 m at bjørnøy-banken showed contrasting results; mosselbukta samples showed that ichnotaxa were equally common (λ close to 0) with a high diversity (1-λ′ = 1), although h′(loge ) demonstrated that several architectural designs were found. ichnodisparity indices were generally even (j′ closer to 1 than to 0) and marked by several groups, except for the deep euphotic stations at mosselbukta (table 5, fig. 8d–f). discussion bathymetric distribution our inventory of microbioerosion traces obtained from polar balanids conforms to the general bathymetrical zonation pattern of microendolithic borings (e.g., golubic et al. 1975; schmidt 1992; glaub 1994; vogel et al. 2000; glaub et al. 2002; wisshak 2012), in which cyano-bacterial borings were only identified in the deep euphotic zone, chloroand rhodophyte borings dominated from the euphotic down to the dysphotic zone and traces by fungi occurred primarily in the aphotic zone. for practical reasons, we refer to photic zones, although during the polar night, they become largely irrelevant due to “aphotic” conditions throughout the water column. however, ichnodiversity was found to be surprisingly low in the euphotic zone, where we would have expected a high diversity in borings produced by phototrophic micro-endoliths. as a result, an almost uniform total number of ichnotaxa was observed along the bathymetrical transect, with more traces of organotrophic microendoliths gradually compensating for the decrease of traces produced by phototrophic microphytes towards deeper waters (table 3). hence, whilst the ichnodiversity remains nearly constant, the composition changes with water depth. this finding contrasts the general trend that the highest variety of microbioerosion traces is usually observed in the euphotic zone, with a gradual decrease towards deeper waters (wisshak 2012). we explain this discrepancy with strong environmental fluctuations in the intertidal zone and upper water column (fig. 8a, d; glaub et al. 2007; golubic et al. 2016). the upper part of polar oceans is influenced by extreme seasonal variations, primarily in light levels and temperature, periods of sea ice cover and consequential meltwater influx (figs. 2, 8; wiencke et al. 2006). furthermore, we assume that drift ice piling up along the shore during winter/spring prohibits balanids from growing old and becoming intensely bioeroded before the ice abrades them, which results in colonization and bioerosion only by opportunistic microendoliths and allowing the establishment of only immature, low-diversity microboring trace assemblages. in deeper water, light levels are low throughout the year and variations of temperature and salinity are less extreme (fig. 8a, d), providing stable environmental conditions for organotrophic microendoliths in the dysphotic and aphotic zones. this interpretation is supported by the nmds plots, cluster analyses (fig. 7) and ichnodiversity indices (fig. 8): the shallow euphotic zone, in particular the intertidal zone, is dissimilar to the deeper euphotic zone and beyond. deeper samples can be subdivided into distinct clusters, representing deeper euphotic, dysphotic and aphotic conditions. the observed bathymetrical distribution pattern and anosim results indicate that water depth, affecting the light regime, is the major factor for the establishment of bioerosion trace assemblages in balanids of the polar waters of svalbard. in contrast, the site factor was much less relevant, with mosselbukta and bjørnøy-banken yielding almost the same suite of ichnotaxa at equivalent depth stations (table 3). intensity of microbioerosion comparatively greater abundances of various micro-borings in mosselbukta possibly reflect more favourable environmental conditions. these are also reflected in the presence of rhodoliths beds at intermediate water depths, which have been demonstrated to increase benthic diversity and abundance, owing to an increase in habitat diversity provided by the bio-engineering crustose rhodophyte lithothamnion glaciale kjellman, 1883 (teichert 2014; wisshak et al. 2017; schoenrock et al. 2018; wisshak et al. 2019). mosselbukta is better protected from currents, whilst a strong hydrodynamic regime and the nearby polar front with colder surface temperatures persist at bjørnøy-banken (henrich et al. 1997; wisshak et al. 2017; wisshak et al. 2019). water masses at mosselbukta and around bjørnøy-banken also differ in turbidity, with the strong tidal currents at bjørnøy-banken leading to resuspension of sediment and food particles following every flood tide. this also results in less light reaching the seafloor, as evident from par data logged during two lander deployments at mosselbukta and bjørnøy-banken (wisshak et al. 2019). these factors appear to promote more intense bioerosion in mosselbukta compared with bjørnøy-banken, resulting in a greater abundance of microborings in mosselbukta but not a significant variation in ichnodiversity (tables 2, 3). ichnodiversity versus ichnodisparity whilst ichnodiversity reflects the number of species (ichnotaxonomic richness), ichnodisparity is “a measure of the variability of morphologic plans” (buatois et al. 2017:104) and is based on a classification into categories of architectural designs. within each of these architectural groups present in our data set, there may be different ichnospecies (table 4). a high ichnodiversity does not necessarily mean that the ichnodisparity is also high (see figure 80 in buatois et al. 2017); likewise, the same degree of ichnodisparity does not mean that the same architectural designs are present. the application of the ichno-disparity concept as a complementing approach did not yield clear differences between the two sites or between the various water depths (low r values and significance levels). the ichnodisparity indices (fig. 8c, f) and the nmds plot (fig. 7b) draw a similar picture, with only the intertidal station in mosselbukta showing a different signature that is most likely a result of the low ichnodiversity in the initial microboring trace assemblage (see discussion above). the cluster analysis (fig. 7c, d) for ichnodiversity and ichnodisparity, however, differed in that the ichnodiversity showed four distinct clusters related to the different photic zones, whereas the architectural groups showed three distinct clusters, which are related to “shallow euphotic”, “deep euphotic to dysphotic” and “aphotic” conditions. the diversity in the architectural designs and, therefore, boring behaviour by microendoliths differs to some degree throughout the bathymetric transect, but not between the different sites (fig. 7d). the clustering is statistically not significant, however, probably reflecting a combination of microborings by phototrophs and organotrophs within the different groups. categories including ichnotaxa by phototrophs occurred primarily in the photic zone (e.g., “globular to spherical borings”, “radial borings”), but as the bacterial ichnogenus scolecia belongs together with ichnoreticulina and conchocelichnus to “branched tubular borings”, the design persists throughout the bathymetric transect. comparison with lower latitudes putting our catalogue of the svalbard microborings in the context of global distribution patterns, we compared our findings primarily with two studies with a comparable bathymetrical transect from lower latitudes in the north atlantic: the cold-temperate kosterfjord in sweden and the warm-temperate azores archipelago (further results of ichnodiversity studies in various settings were summarized by wisshak et al. [2011], table 3). this comparison indicates that the svalbard ichnotaxa record complies with the overall bathymetrical decrease of microboring ichnodiversity towards higher latitudes (wisshak 2006; wisshak et al. 2011). although we here compare natural substrates with two-year experimental exposures and despite arctic balanids being mostly older than the analysed platforms, by far the highest ichnodiversity was detected in the azores, a warm-temperate setting with apparently more favourable environmental conditions for microbioerosion (wisshak et al. 2011). at the cold-temperate kosterfjord site, temperatures are colder than in the azores and have a stronger seasonal fluctuation. moreover, the water is more turbid and the photic zonation is considerably condensed, which results in a reduced ichnodiversity (wisshak 2006). svalbard has the lowest temperatures and most strongly limited light regime, combined with the strongest seasonal fluctuations, and this is reflected in the lowest ichnodiversity among the three sites. as far as the spectrum of inferred or assumed microendolithic trace-makers is concerned, 20 microbioerosion traces were documented in svalbard waters. in contrast, nearly twice as many (37) were encountered on experimental settlement platforms in the azores, including 11 cyanobacterial microborings, seven traces by chlorophytes, eight of fungal origin and 11 other organotrophic microborings (wisshak et al. 2011). in the kosterfjord, sweden, an intermediate ichnodiversity of 26 different traces on three different substrate types was recorded. on the experimental substrates, seven of the investigated traces were produced by cyanobacteria, four by chlorophytes, six by fungi and four by unidentified organisms (wisshak 2006). seven microborings at the svalbard sites were attributed to phototrophic microendoliths (three cyanobacteria, two chlorophytes, one rhodophyte trace-maker). this comparison indicates that it is chiefly the depletion in microalgae and cyanobacteria that is reflected in the low ichnodiversity. the polar night, in combination with a condensed photic zonation during the polar day and transitional months, imposes significant limitations for these photo-trophic organisms. in consequence, traces produced by low-light specialists were found most abundant in the phototrophic borer spectrum, specifically i. elegans (produced by the chlorophyte ostreobium quekettii bornet & flahault, 1889) and c. seilacheri (produced by bangialean rhodophytes). apart from the seasonal availability of light for photosynthesis (e.g., schmidt & freiwald 1993; zacher et al. 2009), the distribution of microphytes is commonly limited by low temperatures, with only a few specialists coping well with the harsh arctic conditions. few studies of marine arctic microalgae (wulff et al. 2009) have been undertaken, but they all show that abundance and diversity are generally poor (garbary 2001), with only a few endemic species in the arctic (wulff et al. 2009). polar species have different metabolic strategies to adapt to low light availability and low temperatures, such as red algae that accumulate floridean starch grains from food remnants during the polar day to adapt to the polar night (e.g., woelkerling 1990; freiwald & henrich 1994; viola et al. 2001). the different strategies allow perennial algae to survive throughout the polar night (lüning 1985; heimdal 1989; gómez et al. 2009; mcminn & martin 2013). the question of how specific microborers adapt to the polar environment has received little attention and is beyond the scope of the present study. however, euendoliths are generally relatively robust with respect to environmental fluctuations as they are buffered in the microenvironment of their borings (vogel & glaub 2004) and could therefore also be expected to survive the polar night. light availability is irrelevant for organotrophs, and as the temperature becomes more stable towards greater water depths, the conditions are less extreme. organotrophs thrive in cold environments at all water depths and dominate in the aphotic zone. those circumstances influence not only the abundance and diversity of microborings but also the dominant ichnospecies in the various biogeographic realms. samples from the deep euphotic zone were dominantly bored by phototrophic microendoliths. in svalbard, mainly c. seilacheri or i. elegans occurred, whilst the intertidal at kosterfjord was primarily colonized by cavernula pediculata and fascichnus ichnospecies. there, the shallow euphotic zone was characterized by c. pediculata, eurygonum nodosum, fascichnus dactylus and orthogonum fusiferum (wisshak 2006). the most common ichnotaxa at the azores at shallow water depths were e. nodosum and scolecia filosa, both produced by cyanobacteria (wisshak et al. 2011). the dysphotic zone in svalbard was densely colonized and had the highest ichnodiversity, with i. elegans as the most dominant ichnotaxon. in the kosterfjord dysphotic zone, flagrichnus ichnospecies, saccomorpha clava and orthogonum lineare were prominent ichnotaxa, with the same trend in aphotic depths (wisshak 2006). the aphotic zone in svalbard was dominated by fungal microborings, e.g., orthogonum tubulare or s. guttulata. nododendrina europaea and other borings by unknown producers, such as the pyrodendrina ichnospecies, resulted in a comparatively high ichnodiversity (table 3). ichnoreticulina elegans was dominant in deep euphotic to dysphotic water samples from the azores, whereas s. clava and n. europaea were common at dysphotic to aphotic depths of the azorean water column (wisshak et al. 2011). this work shows that in spite of the similarity between deep-water conditions at low latitudes and conditions at high latitudes, some ichnotaxa common in warmand cold-temperate realms—such as the cyanobacterial ichnotaxa e. nodosum and s. filosa and the chlorophyte microborings in the ichnogenus rhopalia—were not observed in the polar region under investigation. ichno-taxa so far exclusive to the cold-temperate and polar realm are f. baiulus, entobia mikra, n. europaea and s. guttulata (wisshak & porter 2006; bromley et al. 2007; wisshak 2008; wisshak et al. 2018, respectively); all of them assumingly bored by fungi, foraminifera and sponges. orthogonum-form 1 was until now also only described from the kosterfjord and is therefore also restricted to cold-temperate and polar regions (wisshak 2006). saccomorpha clava is usually a ubiquitous fungal ichnotaxon (e.g., wisshak 2006; wisshak et al. 2011; färber et al. 2015), but only one single colony was observed in mosselbukta, whilst we commonly found s. guttulata as a substitute of this trace. fascichnus isp. i, ii or flagrichnus cf. baiulus are informally described and referred to as “cf.” in the present study, because they show “undescribed” features or an adapted boring behaviour and are thus different to the original diagnosis. those “adaptations” may be effects of the limiting environmental parameters. conclusions we address the lack of comprehensive arctic (micro)bioerosion research by presenting a catalogue of 20 different ichnotaxa that we have recorded in more than 100 balanid samples from euphotic to aphotic depths from two polar carbonate factories in svalbard waters. a remarkably low ichnodiversity was observed in shallow euphotic waters, which is herein explained by limitations in the availability of multiannual balanids as substrate and by the harsh environmental conditions characterized by a lack of par during the polar night, low and fluctuating temperatures and the influence of sea ice. light availability is the most significant factor for the establishment of different microbioerosion trace assemblages in different water depths. the extreme light regime and low temperatures led to a depletion of particularly the phototrophic microborer spectrum that lacks several of the “usual suspects” among the ichnotaxa commonly encountered in lower latitudes. overall, this results in a comparatively low ichnodiversity that accords with a general decrease in ichnodiversity towards higher latitudes. more studies, considering different types of substrate, further polar sites in both hemispheres and studies of the bioerosion rate, are needed to gain a more complete picture of the role of bioerosion in polar carbonate factories. acknowledgements we thank the crew of the rv maria s. merian on the msm55 cruise and the geomar jago team for helping to recover our samples. we acknowledge alexander bartholomä (senckenberg am meer, wilhelmshaven) for providing bathymetry data for fig. 1 and nicol mahnken (senckenberg am meer, wilhelmshaven) for her support during sample preparation. we also thank the reviewers ana santos and nicholas minter for their constructive comments and suggestions on the manuscript that helped us to improve it. references aitken a.e. & risk m.j. 1988. biotic interactions revealed by macroborings in arctic bivalve molluscs. lethaia 21, 339–350, doi: 10.1111/j.1502-3931.1988.tb01762.x. akpan e.b. & farrow g.e. 1985. shell bioerosion in high-latitude low-energy environments: firths of clyde and lorne, scotland. marine geology 67, 139–150, doi: 10.1016/0025-3227(85)90152-5. barnes h. & barnes m. 1954. the general biology of balanus balanus (l.) da costa. oikos 5, 63–76. barnes h. & powell h.t. 1953. the growth of balanus balanoides (l.) and b. crenatus brug. under varying conditions of submersion. journal of the marine biological association of the united kingdom 32, 107–127, doi: 10.1017/s0025315400011450. bornet e. & flahault c. 1889. sur quelques plantes vivant dans le test calcaire des mollusques. (about some plants living in the calcareous shell of molluscs.) bulletin de la societe botanique de france 36, 147–179, doi: 10.1080/00378941.1889.10835893. bromley r.g. 2004. a stratigraphy of marine bioerosion. in d. mcillroy (ed.): the application of ichnology to palaeoenvironmental and stratigraphic analysis. pp. 455–479. london: geological society. bromley r.g. & hanken n.-m. 1981. shallow marine bioerosion at vardø, arctic norway. bulletin of the geological society of denmark 29, 103–109. bromley r.g., wisshak m., glaub i. & botquelen a. 2007. ichnotaxonomic review of dendriniform borings attributed to foraminiferans: semidendrina igen. nov. in w. miller (ed.): trace fossils: concepts, problems, prospects. pp. 518–530. amsterdam: elsevier science. bruguière j.g. 1789. encyclopédie méthodique ou par ordre de matières. histoire naturelle des vers. (methodical encyclopedia by order of subject matter. natural history of worms.) paris: panckoucke. buatois l.a., wisshak m., wilson m.a. & mángano m.g. 2017. categories of architectural designs in trace fossils: a measure of ichnodisparity. earth-science reviews 164, 102–181, doi: 10.1016/j.earscirev.2016.08.009. färber c., wisshak m., pyko i., bellou n. & freiwald a. 2015. effects of water depth, seasonal exposure, and substrate orientation on microbial bioerosion in the ionian sea (eastern mediterranean). plos one 10, e0126495, doi: 10.1371/journal.pone.0126495. feussner k.-d., skelton p.a., south g., alderslade p. & aalbersberg w. 2004. ostreobium quekettii (ostreobiaceae: chlorophyceae) invading the barnacle acasta sp. (pendunculata: acastinae), endozoic in the octocoral rumphella suffruticosa (alcyonacea: gorgoniidae) from fiji, south pacific. new zealand journal of marine and freshwater research 38, 87–90, doi: 10.1080/00288330.2004.9517220. feyling-hanssen r.w. 1953. the barnacle balanus balanoides (linne, 1766) in spitsbergen. norsk polarinstitutt skrifter 98. oslo: norwegian polar institute. fischer m.p. 1875. d’un type de sarcodaires. (about a species of protoplasmic organisms.) journal de zoologie 4, 530–533. freiwald a. & henrich r. 1994. reefal coralline algal build-ups within the arctic circle: morphology and sedimentary dynamics under extreme environmental seasonality. sedimentology 41, 963–984. garbary d.j. 2001. biogeography of marine algae. in: encyclopedia of life sciences. hoboken, nj: john wiley & sons. doi: 10.1038/npg.els.0000312. glaub i. 1994. mikrobohrspuren in ausgewählten ablagerungsräumen des europäischen jura und der unterkreide (klassifikation und palökologie). (microboring traces in selected depositional environments of the european jurassic and lower cretaceous [classification and paleoecology].) frankfurt: senckenberg nature research society. glaub i., gektidis m. & vogel k. 2002. microborings from different north atlantic shelf areas—variability of the euphotic zone extension and implications for paleodepth reconstructions. courier forschungsinstitut senckenberg 237, 25–37. glaub i., golubic s., gektidis m., radtke g. & vogel k. 2007. microborings and microbial endoliths: geological implications. in w. miller (ed.): trace fossils: concepts, problems, prospects. pp. 368–381. amsterdam: elsevier. golubic s., campbell s.e., lee s.-j. & radtke g. 2016. depth distribution and convergent evolution of microboring organisms. palz 90, 315–326, doi: 10.1007/s12542-016-0308-6. golubic s., perkins r.d. & lukas k.j. 1975. boring microorganisms and microborings in carbonate substrates. in r.w. frey (ed.): the study of trace fossils: a synthesis of principles, problems, and procedures in ichnology. pp. 229–259. berlin: springer. gómez i., wulff a., roleda m.y., huovinen p., karsten u., quartino m.l., dunton k. & wiencke c. 2009. light and temperature demands of marine benthic microalgae and seaweeds in polar regions. botanica marina 52, 593–608, doi: 10.1515/bot.2009.073. greenacre m. & primicerio r. 2013. multivariate analysis of ecological data. bilbao: bbva foundation. hammer ø. & harper d.a. 2008. paleontological data analysis. oxford: blackwell publishing. hanken n., uchman a. & jakobsen s.l. 2012. late pleistocene–early holocene polychaete borings in ne spitsbergen and their palaeoecological and climatic implications: an example from the basissletta area. boreas 41, 42–55, doi: 10.1111/j.1502-3885.2011.00223.x. heimdal b.r. 1989. arctic ocean phytoplankton. in y. herman (ed.): the arctic seas: climatology, oceanography, geology, and biology. pp. 193–222. boston, ma: springer. henrich r., freiwald a., bickert t. & schäfer p. 1997. evolution of an arctic open-shelf carbonate platform, spitsbergen bank (barents sea). in n.p. james & j.a.d. clarke (eds.): cool-water carbonates. pp. 163–181. mclean, va: sepm society for sedimentary geology. doi: 10.2110/pec.97.56.0163. kjellman f.r. 1883. the algae of the arctic sea: a survey of the species, together with an exposition of the general characters and the development of the flora. kongliga svenska vetenskaps-akademiens handlingar 20. stockholm: royal swedish academy of sciences. korkmaz s., goksuluk d. & zararsiz g. 2014. an r package for assessing multivariate normality. the r journal 6, 151–162. linnaeus c. 1758. systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. (system of nature through the three kingdoms of nature, according to classes, orders, genera and species, with characters, differences, synonyms, places.) vol. 1. 10th edn. stockholm: l. salvii. lüning k. 1985. meeresbotanik: verbreitung, ökophysiologie und nutzung der marinen makroalgen. (marine botany: distribution, ecophysiology and usage of the marine macro-algae.) stuttgart: thieme. luther g. 1987. seepocken der deutschen küstengewässer. (barnacles of the german coastal waters.) helgoländer meeresuntersuchungen 41, 1–43, doi: 10.1007/bf02365098. mcminn a. & martin a. 2013. dark survival in a warming world. proceedings of the royal society of london 280, 201–229, doi: 10.1098/rspb.2012.2909. müller o.f. 1776. zoologiæ danicae prodromus, seu animalium daniæ et norvegiae indigenarum characteres, nomina, et synonyma imprimis popularium. (danish history of zoology, or the native characters of danish and norwegian animals, names and population synonyms.) copenhagen: hallageri. neumann a.c. 1966. observations on coastal erosion in bermuda and measurements of the boring rate of the sponge cliona lampa. limnology and oceanography 11, 92–108, doi: 10.4319/lo.1966.11.1.0092. noaa global monitoring laboratory 2020. sunset table for 2016. noaa solar calculator. us national oceanic and atmospheric administration. accessed on the internet at https://www.esrl.noaa.gov/gmd/grad/solcalc/ on 21 july 2020. norwegian meteorological institute 2019. norwegian ice service. accessed on the internet at http://polarview.met.no/ (now https://cryo.met.no/en/latest-ice-charts) on 10 july 2019. oksanen j., blanchet f.g., friendly m., kindt r., legendre p., mcglinn d., minchin p.r., o’hara r.b., simpson g.l., solymos p., henry m., stevens h., szoecs e. & wagner h. 2018. vegan: community ecology package. in r package version 2.5-3. accessible on the internet at https://cran.r-project.org/package=vegan. quenstedt f.a. 1849. petrefaktenkunde deutschlands. erster band. cephalopoden. (palaeontology of germany. vol. 1. cephalopods.) tübingen: fues, ludwig friedrich. radtke g. 1991. die mikroendolithischen spurenfossilien im alt-tertiär west-europas und ihre palökologische bedeutung. (the microendolithic trace fossils in the early tertiary of western europe and their palaeoecological significance.) frankfurt: senckenberg nature research society. radtke g., campbell s.e. & golubic s. 2016. conchocelichnus seilacheri igen. et isp. nov., a complex microboring trace of bangialean rhodophytes. ichnos 23, 228–236, doi: 10.1080/10420940.2016.1199428. r core team 2018. r: a language and environment for statistical computing. vienna: r foundation for statistical computing. schmidt h. 1992. mikrobohrspuren ausgewählter faziesbereiche der tethyalen und germanischen trias (beschreibung, vergleich und bathymetrische interpretation). (microboring traces in selected facies areas of the tethyan and germanic triassic [description, comparison and bathymetric interpretation].) frankfurt: frankfurter geowissenschaftliche arbeiten. schmidt h. & freiwald a. 1993. rezente gesteinsbohrende kleinorganismen des norwegischen schelfs. (recent rock boring microorganisms of the norwegian shelf.) natur und museum 123, 149–155. schoenrock k., vad j., muth a., pearce d.m., rea b.r., schofield j.e. & kamenos n.a. 2018. biodiversity of kelp forests and coralline algae habitats in southwestern greenland. diversity 10, article no. 117, doi: 10.3390/d10040117. teichert s. 2014. hollow rhodoliths increase svalbard’s shelf biodiversity. scientific reports 4, article no. 6972, doi: 10.1038/srep06972. teichert s., woelkerling w., rüggeberg a., wisshak m., piepenburg d., meyerhöfer m., form a. & freiwald a. 2014. arctic rhodolith beds and their environmental controls (spitsbergen, norway). facies 60, 15–37, doi:10.1007/s10347-013-0372-2. tribollet a., radtke g. & golubic s. 2011. bioerosion. in j. reitner & v. thiel (eds.): encyclopedia of geobiology. pp. 117–134. dordrecht: springer. vallon l.h., rindsberg a.k. & bromley r.g. 2016. an updated classification of animal behaviour preserved in substrates. geodinamica acta 28, 5–20, doi: 10.1080/09853111.2015.1065306. viola r., nyvall p. & pedersén m. 2001. the unique features of starch metabolism in red algae. proceedings of the royal society b: biological sciences 268, 1417–1422, doi: 10.1098/rspb.2001.1644. vogel k., gektidis m., golubic s., kiene w.e. & radtke g. 2000. experimental studies on microbial bioerosion at lee stocking island, bahamas and one tree island, great barrier reef, australia: implications for paleoecological reconstructions. lethaia 33, 190–204, doi: 10.1080/00241160025100053. vogel k. & glaub i. 2004. 450 millionen jahre beständigkeit in der evolution endolithischer mikroorganismen? (450 millions years of persistance in the evolution of endolithic microorganisms?) stuttgart: franz steiner. whitaker d. & christman m. 2014. clustsig: significant cluster analysis. in r package version 1.1. accessible on the internet at https://cran.r-project.org/package=clustsig. wiencke c., clayton m.n., gómez i., iken k., lüder u.h., amsler c.d., karsten u., hanelt d., bischof k. & dunton k. 2006. life strategy, ecophysiology and ecology of seaweeds in polar waters. reviews in environmental science and bio/technology 6, 95–126, doi: 10.1007/s11157-006-9106-z. wisshak m. 2006. high-latitude bioerosion: the kosterfjord experiment. berlin: springer. wisshak m. 2008. two new dwarf entobia ichnospecies in a diverse aphotic ichnocoenosis (pleistocene/rhodes, greece). in m. wisshak & l. tapanila (eds.): current developments in bioerosion. pp. 213–234. berlin: springer. wisshak m. 2012. microbioerosion. in d. knaust & r. bromley (eds.): trace fossils as indicators of sedimentary environments 64. pp. 213–243. amsterdam: elsevier. wisshak m. 2017. taming an ichnotaxonomical pandora’s box: revision of dendritic and rosetted microborings (ichnofamily: dendrinidae). european journal of taxonomy 390, 1–99, doi: 10.5852/ejt.2017.390. wisshak m., bartholomä a., beuck l., büscher j.v., form a., freiwald a., halfar j., hetzinger s., van heugten b., hissmann k., holler p., meyer n., neumann h., raddatz j., rüggeberg a., teichert s. & wehrmann a. 2017. habitat characteristics and carbonate cycling of macrophyte-supported polar carbonate factories (svalbard.) cruise no. msm55. june 11—june 29, 2016. reykjavik (iceland)—longyearbyen (norway). maria s. merian-berichte. bremen: german research foundation, senate commission on oceanography. doi: 10.2312/cr_msm55. wisshak m., gektidis m., freiwald a. & lundälv t. 2005. bioerosion along a bathymetric gradient in a cold-temperate setting (kosterfjord, sw sweden): an experimental study. facies 51, 93–117, doi: 10.1007/s10347-005-0009-1. wisshak m., meyer n., radtke g. & golubic s. 2018. saccomorpha guttulata: a new marine fungal microbioerosion trace fossil from coolto cold-water settings. palz 92, 525–533, doi: 10.1007/s12542-018-0407-7. wisshak m., neumann h., rüggeberg a., büscher j., linke p. & raddatz j. 2019. epibenthos dynamics and environmental fluctuations in two contrasting polar carbonate factories (mosselbukta and bjørnøy-banken, svalbard). frontiers in marine science 6, article no. 667, doi: 10.3389/fmars.2019.00667. wisshak m. & porter d. 2006. the new ichnogenus flagrichnus—a paleoenvironmental indicator for cold-water settings? ichnos 13, 135–145, doi: 10.1080/10420940600851255. wisshak m., tribollet a., golubic s., jakobsen j.c. & freiwald a. 2011. temperate bioerosion: ichnodiversity and biodiversity from intertidal to bathyal depths (azores). geobiology 9, 492–520, doi: 10.1111/j.1472-4669.2011.00299.x. woelkerling w.j. 1990. an introduction. in k.m. cole & r.g. sheath (eds.): biology of the red algae. pp. 1–6. cambridge: cambridge university press. wulff a., iken k., quartino m.l., al-handal a., wiencke c. & clayton m.n. 2009. biodiversity, biogeography and zonation of marine benthic microand macroalgae in the arctic and antarctic. botanica marina 52, 491–507, doi: 10.1515/bot.2009.072. zacher k., rautenberger r., hanelt d., wulff a. & wiencke c. 2009. the abiotic environment of polar marine benthic algae. botanica marina 52, 483–490, doi: 10.1515/bot.2009.082 zenkevitch l. 1963. biology of the seas of the u.s.s.r. london: george allen & unwin ltd. research note reindeer on prins karls forland, svalbard ian gjertz gjertz, i . 1995: reindeer on prins karls forland, svalbard 1995. polar research 1 4 ( 1 ) . 87-88. svalbard reindeer were exterminated on the island of prins karls forland just after the turn of the last century. in july 1994, after a period of 90 years, reindeer were again observed on the island. ian g j e r t z , norsk polarinstitutt, p . 0. box 5072 majorstuen, n-0301 oslo, n o r w a y . the svalbard subspecies of reindeer (rangifer tarandus platyrhynchus) is only found in the sval bard archipelago. when the archipelago was dis covered, around year 1600, reindeer were abundant throughout much of the ice-free parts of svalbard (lon0 1959). since then, excessive hunting reduced the numbers and distribution dramatically. according to wollebaek (1926) hunting drove the reindeer from the easily access ible western coast of spitsbergen, while they were still abundant on the northern and eastern coasts of spitsbergen as well as on b a r e n t s ~ y a and edg e ~ y a . the original size of the reindeer population is not known, but norderhaug (1969) roughly estimated it to be 6000-7000, a figure which must be unrealistically low as britsland & alendal (1985) have shown that there probably were 11,000 reindeer in svalbard in 1980, a time when large tracts of former reindeer habitat had not been recognised. though reindeer could be found throughout large parts of svalbard, they were not abundant in all areas. kongsfjorden apparently had numerous animals, while the animals were less abundant on prins karls forland and in southern spitsbergen. (lano 1959). according to wollebaek (1926), reindeer were exterminated along the western coasts north of isfjorden north to krossfjorden, and on prins karls forland: in addition lon0 (1959) states that in the kongsfjorden-krossfjor den area this may have been as early as in 1861. reindeer in svalbard were totally protected in 1925, but large scale poaching is known to have been common for many decades since then. on prins karls forland reindeer were appar ently exterminated before 1926 (wollebzk 1926). according to bruce (1908), who mapped prins karls forland just after the turn of the century, reindeer were occasionally found on the island. in 1906 bruce (1907) saw two reindeer at the northern end of the island. further south on the island there were two groups of overwintering trappers in 1907. the leader of one of these groups kept a detailed diary in which all game caught or seen were registered (pedersen 1908); however, no mention is made of reindeer. this suggests that reindeer must have been scarce. after the reports of bruce (1907). i have found no observations of reindeer on prins karls for land in the literature or trappers’ diaries from the island. this suggests that the reindeer were exterminated on the island around 1907. since reindeer were rare or also exterminated along the western coast of spitsbergen from kongsfjorden to daudmanns~yra, there was no local source to restock prins karls forland. in 1978, fifteen reindeer were re-introduced to broggerhalv~ya, in kongsfjorden. as part of an ecological experiment. by 1993 there were close to 400 reindeer in the kongsfjorden area (n. a. aritsland, biologist norsk polarinstitutt, personal commun.). the following winter a large part of these animals either perished or moved out of the area. in 1984 and 1985 a total of 12 reindeer were introduced to daudmanns~yra, on the northern side of the mouth of isfjorden (e. persen. con servation officer for svalbard, sysselmannen, per 88 i. gjertz sonal c o m m u n . ) . these animals have slowly increased and in 1994 numbered at least 6c-70 ( h . l u n d , trapper. personal commun.). in the winter of 1994 reindeer could be found in the mountains along the whole coast from daud mannssyra t o kongsfjorden. h a n s lund. who has a trapping station i n the area. claims that there was a marked increase of animals in 1994. this observed increase may therefore be partly explained by the altered situation in kongsfjor den. in july 1991. i hiked o n prins karls forland. from the northern shore of richardlaguna around the northern tip of the island and down the west ern coast to salpynten. the southernmost tip of the island. this trip lasted for six days and i saw two reindeer on the island and signs of more animals. despite the fact that the weather was particularly bad most of the time, with dense fog and little or no visibility. o n the northern tip of the island there were fresh tracks of o n e small reindeer. n o animals were sighted, but this may have been due to the dense fog that prevailed in the a r e a . this area was characterised by rich vegetation d u e to the large bird cliffs and offers excellent grazing opportunities. n o reindeer or tracks were 5een until tvihyrningen. roughly 50 km further south. h e r e two large adult males were observed grazing on thick layers of lichens. based on observations of tracks and faecal matter. it can be assumed that the reindeer had been in the area for some time. but the faecal matter did not appear to be from winter. i.e. loose pellets. in addition, tvihyrningen has a large bird cliff and is therefore richer in vegetation than most of the surrounding areas. t h e large valley, j u s t south of tvihvrningen and connecting the western and eastern coasts of the island. was not inspected. n o more signs of reindeer were observed before salfjellet. the southernmost part of the island. 30 km further south. here several fresh tracks were observed. norsk polarinstitutt and svsselmannen (the governor of svalbard) have been conducting bio logical wrveys at prins karls forland more or less annually since 1985. and hitherto no reindeer have been observed. t h e observations of reindeer presented here are probably the first o n prins karls forland in 87 years. it is not known if the animals walked across the ice from spitsbergen, or swam. as stated earlier reindeer have been re introduced into two areas o n the western coast of spitsbergen; they are now found more or less continuously along the entire coast between these two areas. part of prins karls forland has a rich vegetation and offers excellent grazing for rein deer. these areas had not been grazed for 90 years, and i t has probably just been a matter of time before reindeer from spitsbergen, notably the kongsfjorden a r e a , would move o u t to this large island situated merely 15 km from brsg gerhalvsya. my observations indicate that a minimum of three reindeer were present on the island in july 1994. probably more. according to 0ritsland & alendal (1985). chances that the introduction of three or four reindeer would lead to the devel opment of viable populations a r e slight. t h e intro duction of eight animals, however. would significantly increase the chances of an increase to such a population. a s the number of reindeer on the island is unknown, it remains t o be seen whether the present recolonisation of prins karls forland will be successful. references bruce. w . s 1907: prince charles foreland scorrish grogroph m a g . iy(j7. 141-156. bruce. h’. s. 1908: the exploration of prince charles foreland 190&1907. geograph. j . 32 /2j. 13%150. len0. 0 1959: reinen p i svalbard forrna ( o s h ) 1-7. 1-31. (in norwegian). nordcrhaug. m . 1969: svalhard-rcinen i 1960-irene. beiteareal og hcstand. ihurra (oslol 22. 1 5 s 2 6 4 . ( i n norwegian). bribland. n . & alrndal. e . 1985: svalbardreinen. bestandens storrelsc og livzhrstorie pp. 62-77 i n britsland. n . a (ed ): .siwlburdrcrneii og dens lrusgrundog. norsk polarinstitutt, oslo 7-78 pp. (in norwegian) pedersen. p. 1908: unpublished trapping diary from prim karls forland 1907-1908. diary no. 173. norsk polarinrtiiuii iihrary. oslo. wollchak. a . 1926. the spitsbergen reindeer. rexdtarerau de irorske srarsrmlrrsrerrede spitsbergr,relijpedisjo,ler 4 . 1 71 + 6 pl. possible signs of recovery of the nearly extirpated spitsbergen bowhead whales: calves observed in east greenland research note possible signs of recovery of the nearly extirpated spitsbergen bowhead whales: calves observed in east greenland outi m. tervo,1,2 marie louis,2,3 mikkel-holger s. sinding,2,4 mads peter heide-jørgensen1,2 & rikke g. hansen1,2 1department of mammals and birds, greenland institute of natural resources, copenhagen, denmark 2department of mammals and birds, greenland institute of natural resources, nuuk, greenland 3globe institute, university of copenhagen, copenhagen, denmark 4department of biology, university of copenhagen, copenhagen, denmark abstract the spitsbergen population of bowhead whales (balaena mysticetus) was harvested to near extinction during the whaling era. here, we show possible signs of recovery of the population by reporting observations of two calves in the scoresby sund polynya in east greenland on 2 and 4 may 2022, and it is the first observation of this kind in this area since the early 1900s. keywords balaena mysticetus, calf, spitsbergen population, endangered   citation: polar research 2023, 42, 8809, http://dx.doi.org/10.33265/polar.v42.8809 copyright: polar research 2023. © 2023 o.m. tervo et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 30 january 2023 competing interests and funding: the authors report no conflict of interest. this study was funded by the greenland institute of natural resources and the national environmental protection agency, danish ministry of environment, under the programme for cooperation on the environment in the arctic (dancea). correspondence: outi m. tervo, department of mammals and birds, greenland institute of natural resources, strandgade 91, dk-1401 copenhagen, denmark. e-mail: outi@ghsdk.dk   introduction the spitsbergen population of bowhead whales (balaena mysticetus) is listed as endangered on the international union for conservation of nature red list (cooke & reeves 2018). the population, which once ranged from the east greenland sea across the northern barents region into russian waters in the north atlantic and numbered between 25 000 and 100 000 individuals (allen & keay 2006), was hunted to near extinction during the whaling era from the 1600s to the early 1900s (ross 1993). population estimates since have ranged from only a few tens of individuals to some hundred individuals (gilg & born 2005; boertmann et al. 2015). the part of the population of bowhead whales residing in the northeast water, off east greenland, a former northern whaling ground, is currently estimated to consist of about 300 individuals (vacquié-garcia et al. 2017; hansen et al. 2017). during recent decades, bowhead whales have been seen with increasing frequency throughout their former distribution range (gilg & born 2005; boertmann et al. 2009; lydersen et al. 2012; boertmann et al. 2015; de boer et al. 2019), but the concurrent increase in survey effort has left doubt about an actual increase in abundance. in the summer of 2009, a calf was seen in the northeast water off east greenland, providing evidence for reproduction in the population (boertmann & nielsen 2010). this observation was the second observation of a calf in the spitsbergen population of bowhead whales since 1981 and the first of its kind in the western part of their range (boertmann & nielsen 2010). here, we provide further evidence for reproduction in the population by reporting observations of two bowhead whale calves in the greenland sea, about 1000 km south of the previous observation. observations a visual aerial line transect survey of marine mammals, following the methodology described by hansen et al. (2017), was conducted in the scoresby sund polynya and adjacent coastal areas between 67.8°n and 71.5°n from 1 to 6 may 2022. two bowhead whale mother–calf pairs were observed, one on 2 may (70°50’6.36”n, 19°2’21.12”w) and one on 4 may 2022 (70°5’1.32”n, 20°19’8.4 w), in the so-called southern whaling ground (fig. 1). the whales were observed about 140 m from the transect line on both occasions. fig. 1 the locations of bowhead whale sightings during the survey in 2022: two bowhead whale mother–calf pairs (red stars) and two additional adults (black dots). the mother–calf pair observations were made on 2 and 4 may, about 100 km apart, qualifying them as observations of unique individuals. the yellow stripes indicate the approximate location of the southern whaling ground utilized between the early 1600 and 1900s (allen & keay 2006). the yellow-shaded oval marks the general area of the scoresby sund polynya. (illustration of the bowhead whale calf by u. gorter.) the calves were grey in colour and were approximately one-quarter of the length of the mothers (fig. 2). we have pictures of only the cow calf pair observed on 4 may. bowhead whale females >13.5 m in length are considered sexually mature (koski et al. 1993), and we estimate that the female observed on 4 may (fig. 2) was 14–16 m in length. the presence of white on the peduncle and several scars on the back and rostrum of the mother suggest that she was not a young whale (b. koski, pers. comm.). bowhead whale calves are 4.0–4.5 m long at birth (koski et al. 1993; heide-jørgensen et al. 2012), with an early growth rate of 1.5 cm/day (koski et al. 1993). judging by its light grey colouring and small size, the calf seen on 4 may was deemed likely to be in the range of newborn to a few weeks in age and unlikely older than one month (b. koski, pers. comm.). fig. 2 the cow–calf pair observed on 4 may 2021. (photo: b. jóhannesson.) both of the pairs were observed resting at the surface in a lead surrounded by dense sea ice (90% ice coverage), which appears to be common for bowhead whale cows with neonates (b. koski, pers. comm.). this suggests that the calf was born in late april or early may, which agrees with the old whaling records of neonate bowhead whales in the greenland sea (scoresby 1820, cited by reeves & leatherwood 1985) and with the most recent sighting of a calf in 2009 (boertmann & nielsen 2010). additional two adult bowhead whales were observed during the survey (fig. 1). recent satellite tracking has shed light on the habitat use and movements of the spitsbergen population of bowhead whales (lydersen et al. 2012; kovacs et al. 2020). the whales were strongly affiliated with cold water and sea ice throughout the year and exhibited an unusual springtime migration from north-to-south, into the southern whaling ground and the scoresby sund polynya area (lydersen et al. 2012; kovacs et al. 2020), where the observations of calves reported here were made (fig. 1). this migration has been suggested to be related to prey distribution (gray 1931, cited by lydersen et al. 2012). in the polynyas, surface water is exposed to solar radiation in the spring earlier than the surrounding ice-covered waters, providing favourable conditions for a concentrated plankton bloom (tremblay et al. 2002). bowhead whales have also been shown to utilize dense ice coverage as an anti-predator tactic against killer whales (orcinus orca; e.g., ferguson et al. 2010; matthews et al. 2020). the scoresby sund polynya fulfils the main characteristics of an ideal calving ground: prey, cold water and protection from predators. it remains to be seen if the two observations of calves reported here are a beginning of a positive trend in the abundance of spitsbergen bowhead whales and an indicator of a calving ground for this endangered population. acknowledgements we thank bill koski, lgl limited, for his insights and advice on aging the calves. ana rodrigues and an anonymous reviewer are thanked for their valuable feedback, which greatly improves this research note. norlandair pilots j. jonsson gentry and b. jóhannesson are thanked for skilful flying and photography. references allen r.c. & keay i. 2006. bowhead whales in the eastern arctic, 1611–1911: population reconstruction with historical whaling records. environment and history 12, 89–113, doi: 10.3197/097634006776026791. boertmann d., kyhn l.a., witting l. & heide-jørgensen m.p. 2015. a hidden getaway for bowhead whales in the greenland sea. polar biology 38, 1315–1319, doi: 10.1007/s00300-015-1695-y. boertmann d., merkel f. & durinck j. 2009. bowhead whales in east greenland, summers 2006–2008. polar biology 32, 1805–1809, doi: 10.1007/s00300-009-0690-6. boertmann d. & nielsen r.d. 2010. a bowhead whale calf observed in northeast greenland waters. polar record 46, 373–375, doi: 10.1017/s0032247410000070 cooke j. & reeves r. 2018. balaena mysticetus (east greenland–svalbard–barents sea subpopulation). the iucn red list of threatened species 2018, e.t2472a50348144 (2018). accessed on the internet at https://doi.org/10.2305/iucn.uk.2018-1.rlts.t2472a50348144.en on 21.5.2022. de boer m.n., janinhoff n., nijs g. & verdaat h. 2019. encouraging encounters: unusual aggregations of bowhead whales balaena mysticetus in the western fram strait. endangered species research 39, 51–62, doi: 10.3354/esr00948. ferguson s.h., dueck l., loseto l.l. & luque s.p. 2010. bowhead whale balaena mysticetus seasonal selection of sea ice. marine ecology progress series 411, 285–297, doi: 10.3354/meps08652. gilg o. & born e.w. 2005. recent sightings of the bowhead whale (balaena mysticetus) in northeast greenland and the greenland sea. polar biology 28, 796–801, doi: 10.1007/s00300-005-0001-9. hansen r.g., boye t.h., larsen r.s., nielsen n.h., tervo o.m., nielsen r.d., rasmussen m.h., sinding m.h.s. & heide-jorgensen m.p. 2017. abundance of whales in west and east greenland in summer 2015. nammco scientific publications 11, doi: 10.1101/391680. heide-jørgensen m.p., garde e., nielsen n.h., andersen o.n. & hansen s.h. 2012. a note on biological data from the hunt of bowhead whales in west greenland 2009–2011. journal of cetacean research and management 12, 329–333. koski w.r., davis r.a., miller g.w. & withrow d.e. 1993. reproduction. in j.j. burns et al. (eds.): the bowhead whale. pp. 239–274. lawrence, ks: society for marine mammalogy. kovacs k.m., lydersen c., vacquiè-garcia j., shpak o., glazov d. & heide-jørgensen m.p. 2020. the endangered spitsbergen bowhead whales’ secrets revealed after hundreds of years in hiding. biology letters 16, article no. 20200148, doi: 10.1098/rsbl.2020.0148. lydersen c., freitas c., wiig ø., bachmann l., heide-jørgensen m.p., swift r. & kovacs k.m. 2012. lost highway not forgotten: satellite tracking of a bowhead whale (balaena mysticetus) from the critically endangered spitsbergen stock. arctic 65, 76–86, doi: 10.14430/arctic4167. matthews c.j.c., breed g.a., leblanc b. & ferguson s. 2020. killer whale presence drives bowhead whale selection for sea ice in arctic seascapes of fear. proceedings of the national academy of science of the united states of america 117, 6590–6598, doi: 10.1073/pnas.1911761117. reeves r.r. & leatherwood s. 1985. bowhead whale balaena mysticetus linnaeus, 1758. in s.h. ridgway & r. harrison (eds.): handbook of marine mammals. volume 3: the sirenians and baleen whales. pp. 305–344. london: academic press. ross w.g. 1993. commercial whaling in the north atlantic sector. in j.j. burns et al. (eds.): the bowhead whale. pp. 511–561. lawrence, ks: society for marine mammalogy. tremblay j.-é., gratton y., carmack e.c., payne c.d. & price n.m. 2002. impact of the large-scale arctic circulation and the north water polynya on nutrient inventories in baffin bay. journal of geophysical research—oceans 107, article no. 3112, doi: 10.1029/2000jc000595. vacquié-garcia j., lydersen c., marques t.a., aars j., ahonen h., skern-mauritzen m., øien n. & kovacs k.m. 2017. late summer distribution and abundance of ice-associated whales in the norwegian high arctic. endangered species research 32, 59–70, doi: 10.3354/esr00791. weather influence on passive microwave brightness temperatures stlg m . lbvks. irene rubinstein and christian ulstad levbs. s. m., rubinstein. i . & ulstad, c. 1994: weather influence on passive microwave brightness temperatures. polar research 13. 67-81, sca ice charts produced using spacebornc passive microwave observations are used on routine basis at several ice forecasting centres and during sea ice research campaigns. the capability of passive microwave sensors to monitor thc earth. regardless of cloud cover or daylight, and the 1400 km swath width (ssm/i) makc thesc sensors well suited not only for ice forecasting but also for providing information needed for planning northern oceanic routes. the retrieval of sea ice parameters is carried out by utilizing 37 and 19 ghz brightness tempcraturcs measured by special sensor microwave imager (ssm/i) on the defense meteorological satellite program (dmsp) platform. the ice type identification uses a-priory established signature brightness temperatures for each ice type. the algorithm generating the sea ice information contains some climatological information on the weather dependence of the observed brightness tempera ture. a comparison between passivc microwave (ssm/i) retrieved ice parameters and ice maps from the nonvcgian meteorological institute (dnmi) indicates that the weather correcting procedure within the algorithm may need rcgionalized input. the correlation of variability of the observed brightness tem peratures with the weather changes has to be derived prior to introducing any corrections to the existing algorithms. thc observed brightness temperatures contain information not only about the ice surface but also the atmosphcrie contribution. one o f the crucial tasks is to establish a technique for flagging changes o n thc ice surface in order to scgrcgate them from the atmospheric influence on the passive microwave signal. to obtain more knowledge about the effects of regional weather on the rctricval of sea ice parameters, local climatological information from dnmi has been compared with the ssm/i ice charts. this paper focuses o n thc outcome of this comparison and how regional atmospheric information can be used in thc retrieval of sea ice information from passive microwave data. s . m . l @ v d s , s i n t e f n h l . n-7034 trondheim. n o r w a y ; 1. rubinstein. institute f o r space and terrestrial science ( i s t s ) , y o r k university. 4850 keele street. north y o r k . ontario, c a n a d a m3j 3 k i : c. ulftad, norwegian meteorological institute ( d n m i ) , p . o . box 43 blindern, n-0313 oslo. n o r w a y . introduction the remote sensing of sea ice with active and passive microwave sensors has become an indis pensable tool to the polar research community. the traditional sources of sea ice information are now augmented with the data obtained from interpretating special scanning microwave imager (ssm/i) multi spectral passive microwave observations. the study of physical properties of the earth’s surface and atmosphere with microwave radio metry became possible with the launch of cosmos-243 (basharinov et al. 1971). single frequency nimbus-5 electrically scanning micro wave radiometer (esmr) observations from 1972 to 1976 provided for the first time a set of global observations that allowed sea ice studies on a synoptic scale (staelin et al. 1973; zwally 1984). since june 1978, multispectral dually pol arized observations (scanning multichannel microwave radiometer on seasat and later on nimbus-7, special scanning microwave imager on dmsp (hollinger et al. 1987)) of the earth microwave radiance have been used in monitoring the extent and physical properties of the sea ice cover and other geophysical parameters. algorithms for translating the microwave measurements into sea ice cover parameters evolved after 1978, when scanning multichannel microwave radiometer (on nimbus-7) data were used to establish the ice monitoring capa bilities of passive microwave sensors. at the insti tute of space and terrestrial science at york university, an algorithm known as the aes/york algorithm has been developed. the algorithm utilizes the ssm/i channels 19 and 37 ghz (both polarizations) to produce sea ice information (total ice concentration, first year ice fraction, old ice fraction and thin/new ice fraction) and wind speed and cloud cover information for ice 68 s. m . l @ u h et al. free pixels. (ramseier et a1 1989; hollinger 1991). the aes/york algorithm is calibrated against ground truth measurements from several ice infested waters. observations from several surveys (also in the barents sea) have shown generally good agreement with the total ice con centration values provided by the algorithm. a study on the variations in ice type fraction in the barents sea based on ssm/i ice charts from september 1988-may 1989 (lw& et al. 1991) showed that the amount of old ice and thin ice varied in reverse proportion. the existence of old ice is far more important to the design and operation of vessels and marine structures than new ice, hence a correct discrimination between old ice and new ice is important. materials and methods data sets the data used in this project were acquired from march 22 through april 10 1992 and are as follows: table 1 . remotely sensed data and derivatives. ssm/i data from the us defence meteorological avhrr data from the noaa-11 satellite. atmospheric data from the atmospheric limited area model, lamsos, of the norwegian meteorological institute (dnmi). passive microwave multispectral measure ments were obtained from civilian navy data distribution services computer (cnodds) in monterey, california and processed at the earth observations laboratory of the institute for space and terrestrial science in toronto, canada. the dates of ssm/i imagery are listed in table 1. advanced very high resolution radiometer data were obtained from and processed at the t r o m s ~ satellite station (low resolution) and dnmi (full resolution). the full resolution imagery has been processed and histogram enhanced at the meteorological institute sat ellite image processing system misat (misat is an 1% based image processing system with an ivas station as display unit and vax support. the system has been developed by spacetec satellite program. data sets ssm/i avhrr date ice ( 1 9 2 ) time orbit time (low res.) time (full res.) analyses 23 march 0657 cc1636 06:29 0 24 march 06:44 ccl6so 09:27 12:s2 25 march 06:32 cc1664 09: 13 0652 26 march 06: 19 cc1678 10:43 06:29 0 27 march 07:48 cc1693 10:32 28 march 09:17 cc1708 10:20 29 march 1008 30 march 07:lo dd1735 09:s6 05% 0 31 march 0 6 5 6 dd 1749 08:38 dd1637 09:39 1 april 08:25 dd 1764 11:12 04:42 3 april 06:47 cc1791 10:25 cc1792 09:w 4 april 06:3s cc 1805 10:37 5 april 0757 cc1820 10:25 6 april 09:24 dd1834 10: 13 7 april a7:37 cc1848 10:52 cc1849 1o:ol 8 april 08:s9 dd1863 9 april m:10 dd1878 2 april 06:31 cc1777 11:w 08:ll 0 10 april 09:26 weather influence on passive microwave brightness temperatures 69 a/s, tromso, in cooperation with dnmi). the dates of avhrr imagery are listed in table 1. the atmospheric data were obtained from the lamsos atmospheric model of dnmi. due to the “spin-up”-time when starting a large numeric model, realistic values on the humidity quantities are fully obtained after six hours of running. therefore the data used here are twelve hour prognoses. the following quantities were used: cloud cover in percent (4 levels) relative humidity (7 levels) convective precipitation (accumulated during six frontal precipitation (accumulated during six temperature at 2 m level (above the model top a rectangle containing hopen, bj0rnoya and the southern part of spitsbergen was chosen with 4 of a total of 48 grid points as corners. the time resolution is twelve hours, and the spatial resolution is 50 km. the sea-ice analyses were obtained directly from the daily update of the sea ice conditions in the misat system. they are produced by draw ing curves on the displayed imagery, using the graphical system in misat. the dates of analysis are listed in table 1. hours) hours) ography) retrieval of sea-ice parameters from spaceborne passive microwave observations the microwave radiation from the earth is a com plex function of the temperature, physical com position and properties of the earth surface altered by the absorption, emission and scattering from the atmosphere. the quantitive deter mination of the environmental parameters is obtained from a limited set of relatively noisy microwave radiation measurements. in general these measurements are not sufficient for unique determination of the environmental parameters without some a priori empirical knowledge and mathematical models on the relationship between these parameters and measured radiometric tem peratures. the empirical information is used to impose limits within which these parameters can vary. the accuracy of the retrieved information is therefore affected by the noise in the empirical data and the uncertainties in assumptions used in model equations. the brightness temperature, tb, is defined as the temperature t i n k (kelvin) to which a black body must be raised in order to radiate with the same intensity. the brightness temperatures measured by the sensor, for any of the sensor channels, contain contributions from the earth, atmosphere and space radiation. assuming non precipitating atmosphere, the observed bright ness temperature can be expressed as: tb = tbsexp(-t) + ti + (1 e)t2exp(-t) where tbs is the surface radiation, t is the atmospheric opacity, t i is the atmospheric upwelling radiation, e is the surface emissivity, t2 is the downwelling atmospheric radiation and tc is the cosmic space contribution. the atmospheric components, under assumptions stated above, can be expressed in terms of an atmospheric mean temperature t,. in polar regions, for the fre quencies used in the algorithms, the atmospheric opacity is small, but not negligible. due t o the noncoherent nature of the natural microwave emission from the surface, the surface radiation can be written as a sum of contributions from different ice types and open water. equation 1 can be rewritten for the following scenarios: 1) single channel, dually polarized observations; 2) dual frequency, same polarizations for both channels. (1): the surface radiation term, if c represents the fraction of the footprint covered with ice, can be written as: + (1 e)t,exp(-2t) (1) where subscript p represents vertical or horizontal polarization, tbip is ice signature brightness tem perature and tbwp is the open ocean signature brightness temperature. the surface emissivity can also be written as a sum of the emissivities from ice fraction and open ocean: ep = ceip + (1 c)ewp (3) substitution of equations 2 and 3 into equation 1 yields equations 4 and 5 for vertical and hori zontal polarizations respectively: tbv = exp( t)[ ctbiv + (1 c)tbwv + 1 (cewv ceiv)tzl + ti + (cewv ceiv)tc x exp( -2t) (4) tbh = exp( t)[ctbih + (1 c) tbwh + (cewh ceih>tz1 + ti + (cewh ceih)tc x exp(-2t) ( 5 ) i0 s. m. l@utfs et al. taking the difference between equations 4 and 5 and neglecting contribution from space yields following expression for c: c = [exp(r)dtbvh dtbw]/[dtbi dtbw + (dew dei) t2] dtbvh = tbv tbh dtbi = tbiv tbih dtbw = tbwv t b ~ h dew = eev ewh (6) (7) (8) (9) (10) (11) c = a d t b w + b (12) where: de. = e e. i iv ih general form of equation 6 can be written as: coefficients a and b are calculated using equation 6. equation 12 (when the assumption is made that the difference between vertical and horizontal sea ice brightness temperatures is inde pendent of ice type) is known as hughes algor 1.6 _ _ _ _ _ . . . . _ . . 1.4 1.2 1 b _ _ _ _ . 2 g 0.8 e 2 . 0.6 0.4 0.2 a 0 _ _ _ _ _ _ _ _ _ _ _ _ ________________________________________------------- -0.2 sensitive to the sea ice presence within the pixel. in the absence of meteorological information, it can lead to false classification of an ice-free pixel for a wind-roughened ocean or an overcast sky. errors in the calculated concentrations can also occur if an inappropriate value of dtbi is selected as a threshold value for the ice presence within a pixel. the dependence of the coefficients a and b on selection of typical optical opacity and dtb, is shown in figs. 1 and 2. (2): for any two channels (frequency f l and f2) with different sensitivities to the atmospheric conditions and different sea ice and open ocean signatures, equations 4 and 5 can be written as follows: tbi = exp(-ri)[mbil + (1 c ) t b ~ i + (cewi ceil)t21i + + (cewl ceil)tc1 x exp(-2tl) (13) (cew2 ceidt221 + 7'12 + (cew~-cei~)tc2 x exp( -2t2) (14) t b ~ = e x p ( % ) [ c t ~ i ~ + (1 c ) t b ~ ~ + ithm. from this equation one can analyse dependence of the total ice cover estimate on the variability in atmospheric conditions. the varia bility of dtbi with the ice types present within the field of view can also influence the accuracy of the calculations. if the weather conditions are used as an input to calculations of a and b, this assuming that only two ice types are present within the pixel ( c f ~ concentration of ice type one, ce! concentration of the second ice type) and cw is the fraction of open water, the equations 13 and 14 can be solved for the ice fractions under the following constraint: type of an algorithm can be tuned to be very cf, + cm + cw = 1 (15) weather influence on passive microwave brightness temperatures 71 fig. 2. dependency of eo efficients a and b on d t b , . k replacing (1 c) by 1 cf] c,, one can show that solutions for cf] and cfz can be written as: cf1 = a i t b l + b l t b 2 + ci c f ~ = a ~ t b i -k b ~ t b ~ -k c2 (16) (17) c = cf] -k c, = actbl -k b c t b ~ -k cc (18) coefficients a l , b , , c i , az, b2, c2, ac, bc, cc are obtained from equations 13 and 14. good estimates of ice type fraction depends on validity of these coefficients. hence, there is a need for ground truth from different areas and seasons. so far there has only been a few ssm/i ground thruth surveys in the barents sea. such ground thruth measurements can easily be combined with other surveys into the ice-covered areas and would pro vide calibration data to improving the retrieval of barents sea ice parameters. equation 15 explains some of the reasons for the old/new ice fluctuations mentioned in the introduction. if f2 (the second ice type) is classi fied as old ice, then no new ice fraction can be calculated. if f2 does not meet the old ice criteria, then cfz is the new ice fraction. it can be shown that a,-, bc, cc are almost independent of optical opacity, whereas the dependence of a,, b,, ci, a2, b2, c2 on r leads to the uncertainty in old and first year ice type fraction estimates (rubinstein 1986). atmospheric influence on the retrieval of sea ice parameters the atmospheric influence on the observed brightness temperatures, and therefore on the retrieved information, can be evaluated by vary ing the values for the transmittance of the atmos phere and the atmospheric radiation. for non precipitating clouds the optical opacity t can he calculated using the values of the attenuation coefficient, k ~ , by water clouds and fog as reported by haroules & brown (1969): r = k i . m j4.34 (19) the parameter m, is the water content of clouds in g/m3. the atmospheric contribution can be estimated using the following approximation (swift et al. 1984): ti = (1 exp( r)) (1.12 . tcloud 50) we will describe the atmospheric influence on the passive microwave algorithms that contain linear combinations of the observed brightness temperatures. due to the regional and seasonal variabilities of the ice signatures, the aes/ york algorithm contains several ice brightness temperature testing routines. clustering of obser vations containing data representative to different regions is used to define the range of pure sig nature classes. 72 s. m. lmods el al. ssm/i brightness temperatures 260. 2 5 0 . 240. c .2 230. n 0 . l 2 220. 0 u . _ c 210. i n 3 200. m 190. 180. 170. pixels containing mixtures of pure classes can be identified as such if they are located within the limits of the following lines (fig. 3): points along the o f line contain old and first year ice, while open ocean and first year ice mixtures are assumed to be along the wf lines. the wt line defines criteria for water plus new ice pixels. fig. 3 shows several brightness temperatures outside the “ice” area. the cloud cover data points (0) can be separated into two groups. one group are pixels that are ice free, and changes in brightness tem peratures are weather induced. for a calm ocean, the brightness temperature tv3, can reach 220 for overcast sky (no rain), while tvly can be 195. hence, drawing a line from w (the open ocean point) with a slope of 0.75 will separate the two groups. data points below this line is considered ice free, while data points between this line and the wf line probably contain (new/thinner) ice. pixels can erroneously be classified as old ice (+) due to different footprint sizes at 19 ghz (50 km) and 37 ghz (30 km). this is more likely to happen for areas where there are changes in ice concentrations (i.e. diffuse ice to pack ice). fig. 3. scatter plot of t,,, vs. tv3, for old ice (+). thin ice ( x ) and cloud cover (0) footprints in the western barents sca in march/april 1992. the polygon (owtf) shows thc valid area for ice footprints when no atmospheric con tribution is present. the 19 ghz channel will be seeing some of the higher concentrations (higher brightness tem peratures) as compared to 37ghz. if 19ghz brightness temperatures are higher than 37 g h z , the algorithm may declare that old ice is present. resampling the ssm/i data for all channels to represent the same size of footprints will remove some of the ice type classification errors. high ice surface roughness, giving an increased capability to trap snow, can also be the cause for some of the ice to be classified as old. pixels not containing old ice can be identified by using the procedure described in the previous section. since the calculated ice fractions should be real, positive numbers, special tests are per formed on the incoming brightness temperatures if any of the calculated fractions are negative. one of the reasons for the fractions being negative is underestimation of the atmospheric opacity. new calculation of the ice fractions is then per formed with optical opacity set to a different value. if that does not help, the pixel is classified as containing ice type of a positive fraction. the operational usefulness of this algorithm is weather influence enhanced by the following additional procedures: the brightness temperatures for the pixels ident ified as ice free are sent through an oceanic par ameters algorithm. ocean surface winds and cloud cover are calculated for these points. if any of the pixels contained ice and were not classified correctly, then the ocean algorithm will classify them as cloud covered (see fig. 8) on passive microwave brightness temperatures 73 the modular structure of this algorithm allows the use of each of the modules as an individual algorithm. this retrieval technique, although it appears to be more complex than other methods used, can be used for global and regional moni toring of the sea ice parameters. equations 13 and 14 can be used for channels other than 19 and 37 ghz. the structure of the algorithm allows table 2. evaluation of the aes/york algorithm performance (from ramseier et al. 1989). the geographic areas included in the evaluation were the beaufort sea (old and first year ice). the labrador sea (first year ice) and the gulf of st. lawrence (first year ice). the time differences (*) between the satellite orbits and the corresponding validation data were less than 1 hour (class a), bctween 1 and 3 hours (class b) or betwcen 3 and 6 hours (class c). ice concentration ice edge displacement mean diff. accuracy group category ("/.) 95% ci" (km) 95% ci" i combined area pooled i-a, class a i-b, class b i-c, class c lab. class a + b 1-1, ice formation 1-2, winter 1-3, initial ice melt 1-4. ice melt -8.9 -4.2 -6.8 10.3 -6.3 -9.1 -5.5 same as 11-3 same as 11-4 0.9 3.1 1.6 1.1 1.4 1.3 1 .o same as 11-3 same as 11-4 i1 arctic -0.2 i .9 -0.7 2.6 same as 111-2 same as 11-3 same as 11-4 same as 111-2 same as 11-3 same as 11-4 pooled 11-a, class a 11-b, class b 11-c, class c 11-ab, class a t b 1 1 1 . ice formation 11-2, winter 11-3, initial ice melt 11-4, ice melt -8.6 0.4 -7.1 -10.0 -5.8 -9.1 -1.5 -5.1 -11.5 0.9 2.3 1.8 1.2 1.6 1.5 0.5 2.7 2.7 -3.1 -5.1 -4.0 -4.3 2.1 2.9 9.5 3.6 111 gulf of st. lawrence pooled 10.1 111-a, class a -12.1 111-b, class b -5.8 ill-c, class c -12.1 ill-ab, class a + b -7.8 111-1, ice formation -8.9 111-2, winter -11.6 1.6 4.5 2.5 2.2 2.2 2.3 2.9 7.4 6.2 21.1 4.2 4.5 9.6 ice fraction first year ice old ice -8.0 6.5 2.7 2.6 'ci = confidence interval 74 s. m . lauds et al. air temperature precipitation western rarents sea 1992 western harents sea 1092 4 4 2 n 1.5 -2 3 g :: e g -14 : 2 hl 8 5 2.5 5 -10 g -12 y -18 .3 1.5 a -22 & i c . .e i 6 .& .20 2 .24 .26 0.5 -28 -30 91 83 85 87 99 91 93 95 97 9y 101 81 83 85 87 89 91 93 95 97 99 101 time (day number) time (day number) cloud percentage relative humidity western harents sea 1992 western barenrs sea 1992 110, i 105 i too c g ica : 90 0 4 80 4 :: 4 50 8 40 ; l5 5 10 m b o 0 h) 85 p 70 tq d a 80 3 7 0 2 65 30 .i a 4 20 81 83 85 87 89 91 93 95 97 99 101 0 55 81 83 85 87 89 91 93 95 97 99 101 time (day number) time (day number) fig. 4. air temperature (top left). prccipitation accumulated over the last 6 hours (top right), cloud perccntagc (fog) at loo0 iipa lcvcl (bottom left), and rclativc humidity at 1ooohpa lcvel (bottom right) from lamsos model calculations. switching to different channels since most of the constants are calculated from the signature bright ness temperatures. the performance of the algorithm described above was evaluated for different geographical regions using ssm/i data for 1987 and 1988 and sea ice information provided by the canadian atmospheric environment service (aes) ice centre. results of the evaluation are shown in table 2. the sea ice charts generated using this algorithm were used successfully for navigational support during sea ice research campaigns in the greenland sea, barents sea, weddell sea and north atlantic sea. results observations in the western barents sea, spring i992 for some parameters of the atmospheric data generated for this study, fig. 4 shows the vari ations as time series for all 48 grid points. the figures show a cold period from 25 march (day 85) to 2 april. prior to and early in this cold period there was some precipitation. during the period the cloud coverage varied. generally, there was little fog, but there were some days with significant cloud percentages at the 300 850 hpa levels. weather influence on passive microwave brightness temperatures 75 fig. 5. ssm/i total ice concentration on 26 march 1992. the frame shows the location of the ers-1 sar scene (4 hours later). the thick line shows position of the ice edge in the sar image. 76 s. m. l @ v h et al. n70 n77 n76 n75 n74 n73 fig. 6. cloud cover percentages at 500 hpa level on 26 march. weather influence on passive microwave brightness temperatures 77 v70 v77 v76 v75 v74 w 3 dnmi lamsos cloud ercentage a1 500 hpa level day: 0!2-l992 time: 1 2 : o o : o o cut fig. 7. cloud cover percentages at 500 hpa level on 1 april. 78 s. m. l ~ v h et al. n78 n77 "76 "75 n74 "73 i ii e l 6 e18 e20 e22 e24 e26 e28 e30 ssm/i [ ists total ice concentration (1: date: 01-04-1992 orbit: ib84 t h e : 08:47:37 gyt fig. 8. ssm/i total ice concentrations (%. 0 ) and cloud coverage (/lo,+) on 1 april 1992. weather influence on passive microwave brightness temperatures 79 in addition to the ssm/i and avhrr data sets listed in table 1, three ers-1 sar scenes have been acquired (23, 26 and 29 march 1992) to study the ice conditions. ground observations were performed during a vessel survey and several helicopter flights in the period 29 march-3 april. during the helicopter flights the ice conditions were monitored simultaneously by s-vhs video and a flir camera mounted on the underside of the helicopter. fig. 5 shows the total ice concentrations on 26 march. the frame shows the location of the ers-1 sar scene and the location of the ice edge as observed in the sar scene. the figure shows good agreement in ice edge position between the ssm/i and sar data. this was also the case for the other two sar scenes acquired. the ssm/i ice chart from 26 march shows more than 80 per cent total ice concentrations for most of the ice field. during the cold period, freezing occurred forming frazil, grease and pancake ice. the ice edge moved eastwards reaching an easterly maxi mum 1 april. on this day there were 30-50 km frazil/grease ice between the open water and the compacted pancake ice edge. the air temperature increased rapidly from 30 march to 3 april due to the winds turning eastwards and further south wards. since the wind direction changed from off ice to on-ice, the newly formed ice was com pressed and the ice edge moved westwards. the easterly winds led t o an ice concentration close to 100 per cent from the ice edge into the ice field. during such conditions ssm/i seem to under predict the ice concentrations slightly. observations on 26 march and i april 1992 to study brightness temperatures during different weather conditions the data from 26 march and 1 april 1992 are selected. the daily ssm/i ice charts monitored total ice concentrations and the location of the compacted ice edge very well. figs. 6 and 7 show the cloud percentages from lamsos at 500hpa level for 26 march and 1 april respectively. despite the high cloud per centages the aes/york algorithm detected the compacted ice edge position very well on both days. the ers-1 sar image from 26 march showed only a few kilometres of frazil ice outside the compacted ice edge. hence, the frazil ice will have less influence on the brightness temperatures on this day than on 1 april where observations from helicopter showed frazil/grease ice up to ssm/i brightness t e m p e r a t u r e s 2 6 0 . 250. c 0 240. n h 230. . . a = 220. 0 . e 2 2 1 0 . i 200. 0 190. m n i c 180. 170. 150. i a o . i c 0 . 2 0 0 . 2 i o . 2 2 0 . z 3 0 . 2 4 0 . 2 5 0 . z 6 o . 37 chz vertical polorizotion ssm/i b r i g h t n e s s t e m p e r a l u r e s 260. 250. .$ 240. 230. c 0 n . 0 a 220. l 210. i 200. 0 u . e 2 6 190. !?! n 180. 170. 37 chz verticol polorizotion fig. 9. scatter plots of t,,, vs. tv3, for first year ice ( a ) , old ice (+), thin ice ( x ) and cloud cover (0) footprints in the area 74on-77"n and 2ooe-35"e 26 march (top) and 1 april (bottom) 1992. the polygon ( o w ) shows the valid area for ice footprints when no atmospheric contribution is present. 40-50 km outside the compacted ice edge. this frazil/grease ice area was not reported as ice by ssm/i, but was interpreted as cloud cover (fig. figs. 9 and 10 show scatter plots of tvl9 vs. tv3, and th37 vs. tv3, respectively for first year ice, 8) 80 s. m. lbvds et al. ssm/i b r i g h t n e s s t e m p e r a t u r e s 2 6 0 . 240. 0 .c .! 2 2 0 . 0 0 a. 0 e 200. c .: 180. 0 l i 160. n s 0 r\ c) 140. 120. 37 verticol polarization ssm/i b r i g h t n e s s t e m p e r a t u r e s 2 6 0 . e 240. . l .:: 2 2 0 . 0 a ' 160. 0 2 b 1 4 0 . r 120. 37 chi verticol polorizotion fig. 10. scatter plots of ths7 vs. tvj7 for first year ice ( a ) , old ice (+), thin ice ( x ) and cloud cover (0) footprints in the area 74on-77"n and 20"e 35"e 26 march (top) and 1 april (bottom) 1992. the straight lines in the figures show the 0% and 100% total ice concentration lines and the wf line. old ice, thin ice and cloud cover (over ocean) footprints in the area 74on-77"n and 2ooe-35"e on 26 march and 1 april 1992. the 37 ghz scatter plot from 26 march (fig. 10 top) shows brightness temperatures along the wf line while the similar plot from 1 april (fig 10. bottom) shows bright ness temperatures along a line offset from the wf line. this offset is due to weather effects and results in some ice points being classified as ice free and underprediction of ice concentration. discussion this paper has presented the basic principals and equations for retrieval of sea ice parameters from spaceborne passive microwave observations and has outlined some of the atmospheric influence on the retrieval of sea ice information. figures showing data from 26 march and 1 april 1992 show some of these effects. the aes/york algorithm detects the compacted ice edge very well. also the total ice concentrations estimates are reliable. frazil/grease ice outside the com pacted ice edge may be interpreted as cloud cover. as such ice is of minor importance to navigation this misinterpretation is also of minor importance for navigational use of the sea ice information derived from ssm/i data. the equations presented show that the bright ness temperature from each satellite footprint can be split into three "ice" components; open water and two ice types. the most hazardous sea ice for navigation is old ice. hence the aes/york algorithm first tests for old ice fraction. if the old ice criteria is met, the remaining ice fraction is the first year ice fraction. however, if no old ice is detected the algorithm calculates the fraction of first year and thin (new) ice. changes in the weather (especially air temperature) may cause the algorithm to switch from identifying old ice one day to thin ice a day or two later (or vice versa). however, by following the changes in ice conditions from day to day such rapid changes in ice conditions will be revealed. if a satellite footprint is classified as ice free, cloud cover and wind speed information might be derived instead of ice fractions. the data sets derived for this study have not yet been completely analysed and we expect t o know more on how well regional climatological information can improve the interpretation of ssm/i data when this work is finished. references basharinov. a . e . , gurvich, a . s . . yegorov, s. t . , kurskaya. a. a . , matveyev d. t. & shutko. a . m. 1971: the results of microwave sounding of earth's surface according to exper weather influence on passive microwave brightness temperatures 81 imental data from cosmos 243, space res., 11. akademie verlag, berlin. haroules, g . g . & brown. w. e. 1969: the simultaneous investigation of attenuation and emission by the earth's atmosphere at wavelengths from 4 cm to 8 mm. j . geophys. res. 74, 4453-4471. hollinger, j . , lo. r. & poe, g. 1987: special sensor microwave imager user's guide. naval rcscarch laboratory report. hollinger j . 1991: dmsp special sensor microwave/imager calibrdtion/validation. final report: vol. 11. nrl, wash ington. d.c. l ~ v ~ s , s . m., vefsnmo, s. & ramseier, r. 0. 1991: barents sea ice conditions as observed by passive microwave and other techniques. 2nd wmo operational ice remote sensing workshop, september 10-13. 1 9 9 1 , ottawa, ontario. canada. ramseier. r. o., lapp, d., rubinstein. i . g . & asmus, k . 1989: canadian validation of the ssm/i and aes/york algorithms for sea ice parameters. ists/microwave group report. rubinstein, i . g. 1986: selection of temperature independent dual frequency sea ice algorithm. ph. d assoc. report for aes. toronto, ontario. 155 pp. staclin, d. h.. barctt. a. e.. waters. j . w.. barath. f. t . . johnston, e. j . , rosenkrantz. p. w., grant, n. e., & lenoir, w. r. 1973: microwave spectrometer on the nimbus-5 satel lite. meteorological and geophysical data. science 182, 133% 1341. swift. c. t . , fedor. s . & ramscier. r . 0. 1984: an algorithm to measure sea-ice concentrations with microwave radio meters. j. geophys. res. 90. 1087-1099. zwally. h. j . 1984: observing polar ice variability. annals of glociol. 5 , 191-198. no job name fram strait sea-ice sediment provinces based on silt and clay compositions identify siberian kara and laptev seas as main source regionspor_149 265..282 dirk dethleff1 & gesa kuhlmann2 1 institute for polar ecology, university of kiel, wischhofstraße 1-3, de-24148, kiel, germany 2 gfz german research center for geosciences, potsdam, telegrafenberg, de-14473, potsdam, germany abstract fram strait sea-ice sediments (sis) contain on average more than 94% silt and clay. both fractions were compared with bottom deposits of the kara and laptev seas to identify shelf sources of fine-grained arctic sis. based on silt granulometry and clay mineral assemblages we determined fram strait sis provinces. western fram strait sis has medium to fine silt compositions, whereas eastern fram strait sis is enriched in fine silt. western fram strait sis clays (low smectite/high illite) were statistically grouped with eastern laptev shelf deposits, and are similar to east siberian and north american shelf sources. eastern fram strait sis clays (high smectite/low illite) cluster with shelf deposits of the western laptev sea and the kara sea. we conclude that western fram strait pack ice consisted of a mixture of floes from the laptev sea and sources farther to the east during the 1997 and 1999 sampling periods. eastern fram strait ice originated from sources towards the kara sea. there was an average annual flux of ca. 158 tg (mt) sis export through fram strait during the late 1990s. we expect no qualitative changes in the sis entrainment process (“suspension freezing”) with decreasing arctic ice cover, although the process may increase through larger fetch. sis incorporation and flux will be enhanced with increasing shelf open water during winter freezing, and with the current acceleration of the transpolar drift, but we speculate that the transport of sis towards fram strait will be seasonally truncated with the onset of ice-free summers in the arctic ocean. keywords fram strait; ice sediment entrainment; kara and laptev seas; sea-ice sediment flux; sea-ice sediment provinces; shelf source deposits. correspondence dirk dethleff, institute for polar ecology, university of kiel, wischhofstraße 1-3, de-24148, kiel, germany. e-mail: ddethleff@ipoe.uni-kiel.de doi:10.1111/j.1751-8369.2010.00149.x although the arctic sea-ice cover is dramatically retreating (rothrock & zhang 2005; stroeve et al. 2005; nghiem et al. 2007; overland et al. 2008), the role of arctic pack ice as a geological agent for the transport of sea-ice sediments (sis) is still important (darby 2003; dethleff 2005; eicken et al. 2005). at present, significant late summer retreat of arctic sea ice can be observed on the shallow siberian and western arctic shelf seas (fig. 1), where processes of sediment entrainment into newly forming ice are most effective during the autumn freeze-up period and in winter polynyas at water depths shallower than 50 m (reimnitz et al. 1993; eicken et al. 2000; dethleff & kempema 2007). the extreme summer ice retreat increasingly provides shallow shelf areas now available for sis entrainment during autumn and winter, which were formerly covered by pack ice year round. sea-ice sediment entrainment occurs during late autumn and winter in shallow, ice-free shelf areas (autumn open water and polynyas). in the process of suspension freezing, turbulent mixing of the water column leads to the incorporation of shelf sediments into new ice (campbell & collin 1958; reimnitz et al. 1992; dethleff & kuhlmann 2009). suspension freezing is driven by turbulent mixing that brings frazil and suspended sediment into contact in the water column, where they form buoyant, sediment-laden flocs that are incorporated into the newly forming ice cover. anchorice formation may also play a role in sis entrainment (reimnitz et al. 1993). minimum concentrations of arctic sis are generally a few mg per litre, whereas turbid sea ice mostly contains about 50–500 mg l-1, with maximum concentrations polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 265 mailto:ddethleff@ipoe.uni-kiel.de reaching 1000 to over 3000 mg l-1 (osterkamp & gosink 1984; larssen et al. 1987; kempema et al. 1988; reimnitz et al. 1993; stierle & eicken 2002). arctic sis mostly consists of silt and clay; sand-sized particles are rare. arctic sis shelf sources have been identified in various studies based on sedimentological, clay mineralogical and geochemical aspects (elverhøi et al. 1989; wollenburg 1993; nürnberg et al. 1994; eicken et al. 1997; reimnitz et al. 1998; darby 2003; dethleff 2005). numerical drift simulations (pfirman et al. 1997; harms et al. 2000) suggest that parts of the eastern kara sea and the entire laptev sea are the main contributors to arctic sis transport towards fram strait melt areas. about 3000 m deep, fram strait is the ocean gateway between svalbard and greenland. it connects the central arctic ocean and the north atlantic (fig. 1). over the last half of the 20th century, about 2900 km3 of sea ice left the central arctic ocean through fram strait and entered the north atlantic annually (vinje et al. 1998; vinje 2001). larssen et al. (1987) estimated the annual sis flux in this ice at 150 tg (mt). arctic sis is melt-released in fram strait and further south along the marginal ice zone year round (e.g., hebbeln & wefer 1991). a higher sediment release can be expected in wintertime as a result of an increase of sea-ice flux resulting from the stronger atmospheric circulation during the polar night (vinje 2001). the kara sea is a semi-enclosed siberian arctic shelf sea bordered by novaya zemlya in the west and north, and by the severnya zemlya archipelago to the east (fig. 1). the sea is generally ice covered from november through june, and annually produces a total drift ice volume of about 900 km3, of which about 250 km3 is exported from the shelf and feeds the central arctic ocean pack ice (kern et al. 2005; martin & martin 2006). our knowledge of the hydrodynamic mechanisms of turbulent sis entrainment in the kara sea is primarily based on modelling efforts (harms et al. 2000; sherwood 2000; smedsrud 2003). in a sedimentological study, dethleff & kuhlmann (2009) investigated the entrainment of silt and clay into new ice formed in a shallow, coastal flaw lead (long extended open water between fast ice and drift ice) in the south-western kara sea. the study showed that newly incorporated sis had the same composition as the shelf surface under the flaw lead. the laptev sea is one of the broadest and shallowest shelf seas of the arctic ocean (fig. 1). according to zakharov (1966), the shelf sea annually produces 800– 1000 km3 of new ice, of which about 250–300 km3 is fig. 1 map of sampling locations in fram strait (circles), the kara sea (triangles) and the laptev sea (squares). the dashed bold line shows the minimum september sea-ice extent averaged for the 1973–76 period (parkinson et al. 1987); this is similar to the median ice extent for september 1979–2000 (overland et al. 2008). the september 2007 minimum arctic sea-ice extent (institute of environmental physics, university of bremen; overland et al. 2008) is displayed as a light-grey region surrounded by a stippled bold line. dark-grey shelf areas indicate regions of less than 50 m water depth, generally available for turbulent sea-ice sediment entrainment. hatched areas in the eastern kara sea, western and eastern laptev sea, east siberian sea, and the chukchi and beaufort seas indicate shelf areas of less than 50 m depth that are additionally available for late autumn and early winter sea-ice sediment entrainment subsequent to the current extreme summer ice retreat. the sample at the stippled triangle location in the south-western kara sea was obtained in 1997 (see text for more details). fram strait sea-ice sediment provinces and sources d. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd266 formed in winter flaw leads (dethleff, loewe & kleine 1998). the ice exported from the laptev sea feeds the tail end of the transpolar drift (tpd). rigor & colony (1997) found that the ice export from this shelf sea accounts for roughly 20% of the total annual ice flux through fram strait. eicken et al. (2000) stated that as much as ca. 20 tg (mt) of bottom sediments were incorporated into new ice formed close to the new siberian islands (laptev sea) during the autumn freeze-up over shallow open water (from <17 m to <30 m) in one individual entrainment event in the 1994/95 season. darby (2003) and dethleff (2005) showed that shallow laptev sea winter polynyas and flaw leads are important sites for the entrainment of fine-grained bottom material into newly forming sea ice. the sediment-laden ice investigated in the above studies was advected offshore and transported through the tpd system towards fram strait. generally, the observed transit times of sea ice formed in the kara and laptev seas towards fram strait are 2–4 years (e.g., colony & thorndike 1985; eicken et al. 1997). however, these times may decrease significantly in the future with the acceleration of the tpd (gascard et al. 2008). the main purpose of this study is to compare sis from northern fram strait and from north of svalbard with the shelf-bottom deposits of shallow kara and laptev sea sites. we provide silt sedimentological and (statistical) clay mineralogical evidence (“fingerprints”) for the ice transport of fine-grained particulate shelf material from the siberian arctic towards the northern north atlantic. based on the sedimentological and mineralogical data, we establish a west-to-east zoning of fram strait and northern svalbard pack-ice provinces related to different siberian shelf sediment source regions. we also determine the sis content in northern fram strait ice-core transects and quantify the ice-sediment flux towards the north atlantic in 1997 (the year of our principal investigation) and as multidecadal annual mean, both in combination with sea-ice export data from vinje (2001). moreover, we discuss the current ice entrainment and transport processes of arctic sis. finally, we briefly speculate on arctic sis entrainment and transport related to the current dramatically changing ice situation on the shallow circum-arctic shelves, and connected to summertime ice-free conditions that will potentially appear by the 2040s or 2050s (e.g., holland et al. 2006). materials and methods a total of 35 sis samples were obtained in fram strait (fig. 1) during the rv polarstern cruise arkxiii/2 (stein & fahl 1997). six sis samples were taken during the arkxv/3 cruise on the same vessel (schauer 2000). the samples were taken from the ice surface, from pressure ridges, from meltwater ponds and from the uppermost core sections of multi-year ice floes. the ice was melted and the sediments were freeze-dried or filtered on preweighed mixed-ester membrane filters (0.45-mm pore diameter). three fjord bottom-surface samples were obtained along the eastern coast of novaya zemlya by box corer during russian–norwegian cruises in the 1990s (samples provided by the norwegian radiation protection authority). one bottom-sediment sample (fig. 1) was obtained from the south-west kara sea during late winter 1997 (dethleff, loewe, weiel et al. 1998) using an ekmanbirge grab (hydrobios, kiel, germany). five kara sea bottom samples (fig. 1) were obtained by box corer during the 49th cruise of the rv dmitry mendeleev (samples provided by the p.p. shirshov institute of oceanology, moscow, russia). seven bottom samples were collected in the eastern laptev sea using a small stainless steel grab during the east siberian arctic region expedition in 1992 (dethleff et al. 1993), whereas the (clay mineral) data of four western laptev sea samples were re-analysed from dethleff et al. (2000). all kara and laptev seas shelf samples were taken at water depths of less than 50 m (fig. 1). simple semi-quantitative estimates (visual scan) of the mineralogical composition of the (coarse) bulk sis and bottom samples were performed using a microscope, with 50-fold magnification (leitz aristoplan, wetzlar, germany). the particles were classified in the following groups: quartz and feldspar, rock fragments, mica, dark minerals, plant debris and other material. all shelf surface and sis samples were separated into s/s/c (sand, silt and clay) fractions. the sand fraction (>63 mm) was obtained by wet sieving, and silt and clay fractions were gravitationally separated using the atterberg method (atterberg 1912). the grain size distribution of the silt fraction (2–63 mm) was analysed using a sedigraph (micromeritics, norcross, ga, usa; see coackley & syvitski 1991 for further details). according to the silt grain size distribution, the samples were classified into silt types following clark & hanson (1983) (fig. 2). sediment statistical parameters (median, mean, sorting, skewness and kurtosis) of the silt fraction were calculated following the method described by folk & ward (1957). the percentages of silt subfractions (coarse: 63–20 mm; medium: 20–6 mm; fine: 6–2 mm) were determined from the sedigraph data. the clay mineralogy of sis and shelf bottom samples was determined using a pw 1830 x-ray diffractometer (copper-k-a radiation, 40 kv, 35 ma; philips, amstelplein, the netherlands) within a spectrum from 2 to 46 2°q in steps of 0.02 2°q s-1 using an automatic divergence slit, fram strait sea-ice sediment provinces and sourcesd. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 267 graphite monochromator and automatic sample holder. the count time at each x-ray diffractometry step was 1 s. tucker (1996) provides a detailed description of this analytical method. illite and smectite were determined from the 10and 17-å peaks, respectively, chlorite was determined from the third-order reflection, and kaolinite was calculated from the 7-å peak. the clay mineral percentages were calculated from peak areas following the procedure proposed by biscaye (1965), and from peak intensities for kaolinite and chlorite after petschick (petschick et al. 1996). for comparison purposes, the results were normalized to 100% for the clay minerals illite, smectite, kaolinite and chlorite. smectite content was determined after glycol-atmosphere treatment of the samples. statistical bray–curtis similarity of clay mineral compositions between fram strait sis and kara and laptev sea bottom sediments was analysed using a multidimensional scaling (mds) test (primer v6; primer-e ltd., ivybridge, plymouth, uk). for quantification of the annual sis flux by the tpd through fram strait, we used the particle content of eight multi-year ice cores (table 1) randomly obtained and nearly equally spaced on two transects north of the fram strait (fig. 3b; stations 8, 12, 13 and 17, and stations 23, 24, 28 and 32) in 1997. the cores were subdivided widely into 10-cm sections; segments of cores with extreme sis concentrations were further subdivided into 5-cm sections. the ice was melted, the particle content of the core sections was filtered on pre-weighed mixed-ester membrane filters (0.45-mm pore diameter) and the particle load was determined in mg l-1 melted sea ice. results sis concentration the sis sampled directly from the ice surface was most concentrated in meltwater ponds and in the extremely turbid layers of tilted floes in pressure ridges. based on visual observations, the pack ice was most turbid in the eastern fram strait and north of svalbard. the lengths of level ice cores obtained in the northern fram strait varied between 1.6 and 3.0 m, and ice thicknesses increased from east to west. sis concentrations in multi-year ice floes were generally highest in the upper core sections, and sometimes peaked at the core surface (fig. 3c, table 1). discrete turbid layers were visible within individual ice cores. the range of sediment content in ice cores ranged from 0.0 to ca. 725.4 mg l-1. the upper turbid 80 cm of the ice cores contained sediment concentrations of less than ca. 3–300 mg l-1, with extreme values exceeding 500 mg l-1. the lower ice-core sections generally contained particle loads of less than 5 mg l-1 throughout. bulk sediment composition quartz and feldspar were the most abundant coarse particle components (about 50–80%) in all bulk sis and shelf surface samples investigated. rock fragments, mica, dark minerals, plant debris and other material were subordinate, or of minor abundance. sand-sized material was generally under-represented in most sis samples (range 0–98.2%, average 7.3%; tables 2, 3). overall, 98% of the sis samples clearly emphasized the fine fraction of less than 63 mm in diameter, which was mainly dominated by silt (average 58.0%; silt to clayey silt sediment type). the average clay concentration for all sis samples was 33.7%. the shelf surface deposits of the kara and laptev seas contained slightly enhanced average sand content (10.8 and 12.2%, respectively; tables 2, 3), as compared with the sis, but silt was still the dominant grain size (average 58.3 and 45.4%, respectively). the south-western kara sea (4, 8 and 9) showed particularly elevated sand content. the average clay percentage in kara and laptev shelf deposits was 30.8 and 42.4%, respectively. for more fig. 2 silt grain size distribution types in fram strait sea-ice sediments (sis) according to the classification of arctic deep-sea silt deposits transported by ice (introduced by clark & hanson 1983). type i is a non-sorted, ice-transported silt with a coarse fraction of about 20%. type ii represents a bimodal, fine-grained, probably current-sorted ice-transported silt (before or after ice entrainment), with a coarse fraction of about 20%. type iii reflects extremely fine-grained ice-rafted silt sediment with a mode in the silt–clay range, and little coarse material. type iv is ice-transported silt with a pronounced medium to coarse silt mode associated with sand content of about 30%. fram strait sea-ice sediment provinces and sources d. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd268 granulometric details of the bulk sample composition see tables 2 and 3. silt fraction the fine-grained composition of the bulk sis was underpinned by the high average fine silt content (59.0%), and by the significantly lower medium and coarse silt fractions (average 28.1 and 12.9%, respectively; tables 2, 3). kara and laptev sea bottom silt was somewhat coarser grained, with a higher average coarse silt portion of 25.2 and 23.0%, respectively, and with an enhanced average medium silt fraction of 32.4 and 51.3%, respectively. more silt granulometric details, like sediment statistical parameters, are shown in table 3, and are discussed below. clay mineral assemblages enhanced smectite values and lower illite concentrations in sis were obvious in eastern fram strait and north of svalbard (fig. 3b; table 3). significantly lower smectite contents associated with clearly enhanced illite concentration were present in the sis from the western parts of fram strait. western kara sea bottom deposits from the east novaya zemlya coast contained no smectite and kaolinite, whereas illite and chlorite concentrations were significantly greater (fig. 3d, tables 1, 3). all other kara sea bottom samples had high portions of smectite, associated with lower contents of illite. western laptev sea bottom deposits also showed high percentages of smectite and lower contents of illite, whereas eastern lapetv sea samples contained lower smectite and higher illite concentrations. kaolinite and chlorite concentrations were much lower in the western laptev sea than in the eastern part (tables 2, 3). fram strait sis flux rate estimates for the assessment of a potential annual maximum, best estimate and minimum sis flux through fram strait, we table 1 sea-ice sediment (sis) content in fram strait ice cores. core sis (mg l-1) core sis (mg l-1) core sis (mg l-1) depth (cm) #8 #13 #17 #23 #28 #32 depth (cm) #12 depth (cm) #24 0 to –10 0.247 68.269 9.241 0.000 501.331 91.068 0 to – 5 725.359 0 to –10 41.323 -20 0.000 103.218 1.933 3.314 96.460 9.242 -10 14.575 -20 8.815 -30 0.000 146.522 3.718 4.465 58.455 16.142 -20 7.303 -30 5.054 -40 0.059 158.052 5.366 2.946 56.173 27.157 -25 2.919 -40 3.968 -50 0.000 75.270 5.944 3.336 52.807 31.551 -30 14.968 -50 5.072 -60 0.000 24.670 4.287 4.633 33.990 103.320 -40 180.183 -60 2.678 -70 0.000 5.054 3.779 5.376 39.898 340.425 -45 18.196 -70 2.791 -80 0.000 2.859 2.554 3.498 17.466 244.800 -55 3.647 -80 4.027 -90 0.000 2.048 2.926 4.786 4.239 22.905 -60 52.804 -90 3.883 -100 0.000 1.280 0.803 8.630 4.467 12.146 -65 40.767 -95 6.178 -110 0.000 4.414 0.417 5.343 3.419 6.504 -75 6.785 -105 20.726 -120 0.000 1.103 0.544 4.396 9.110 24.531 -85 3.784 -110 7.834 -130 0.147 1.924 0.279 0.679 4.174 11.823 -95 1.494 -120 15.619 -140 0.049 4.662 0.000 0.410 6.338 11.643 -105 1.407 -130 7.638 -150 0.000 5.702 0.194 0.414 20.893 29.264 -115 2.826 -140 0.000 -160 0.000 2.646 0.000 0.000 32.460 74.543 -125 0.964 -150 0.082 -170 — 5.265 0.000 — 31.121 595.571 -135 1.016 -160 2.920 -180 — — 0.552 — 20.899 17.097 -145 0.461 -165 8.175 -190 — — 0.272 — 7.394 2.059 -155 0.262 -170 5.748 -200 — — 0.000 — 9.807 1.486 -165 0.126 -180 1.076 -210 — — 1.096 — 10.745 1.738 -175 0.000 -190 0.646 -220 — — — — 17.455 — -185 0.000 -200 2.154 -230 — — — — 5.802 — -195 0.110 -210 0.855 -240 — — — — 2.936 — -205 0.000 -220 0.000 -250 — — — — 0.423 — -215 0.160 -230 0.102 -260 — — — — 0.318 — -225 0.468 -240 0.000 -270 — — — — 0.109 — -235 0.193 -250 0.000 -280 — — — — 1.697 — -290 — — — — 2.035 — -300 — — — — 3.694 — fram strait sea-ice sediment provinces and sourcesd. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 269 fig. 3 (a) arctic map displaying the transpolar drift (tpd) and the beaufort gyre (bg), and showing the areas of investigation. (b) grey shaded areas display sea-ice sediment (sis) silt type provinces emphasized by representative silt sedigraph histograms, according to the clark & hanson (1983) classification. the dashed bold line separates fram strait sis clay cluster provinces a and b, where numbers 1–35 relate to the 1997 rv polarstern cruise, and letters a–f are linked to the 1999 polarstern cruise. solid bold west–east extended lines indicate 1997 ice-core cross sections in northern fram strait. the edge of closed pack ice on 25 july 1997 (stippled bold contour) is depicted from noaa 12 satellite images received by the polarstern as a temporary arctic relays station. the september 1999 ice edge is based on information from the national snow and ice center in boulder. (c) example of the vertical particle distribution in a central fram strait sea-ice core (see [b] for core location). (d) kara sea and (e) laptev sea sampling sites and shelf surface silt and clay mineral distributions. fram strait sea-ice sediment provinces and sources d. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd270 used the following method: the particle load of each individual ice core section (obtained in mg l-1 meltwater; table 1) was normalized to gm-3 of sea ice. we then multiplied this calculated sis load with the annual seaice export through fram strait in 1997 (ca. 3300 km3; see vinje 2001: fig. 3), and with the annual sea-ice export averaged over five decades (ca. 2900 km3; vinje 2001). the maximum sis flux was estimated using the average sediment content (84.4 gm-3) in the upper 80 cm of the four most turbid ice cores (stations 12, 13, 28 and 32; table 1), presuming that all ice exported through fram strait potentially contains such high sediment concentrations. for the best estimate we used the average ice core sediment concentration (45.6 gm-3) from the upper 80 cm of all eight cores obtained, and the minimum estimate was calculated based on the average sediment concentration (23.5 gm-3) of the entire ice cores. the estimates of the annual fram strait sis flux for the two sea-ice export scenarios (2900 km3 as the fivedecadal mean; 3300 km3 in 1997; vinje 2001) are shown in table 4. the maximum sis flux amounted to 245 and 279 tg (mt), respectively. the best-estimate sediment flux was 132 and 150 tg (mt), whereas the minimum flux amounted to 68 and 78 tg (mt), respectively. average values from the maximum, best and minimum sis flux estimates for both the 2900and the 3300-km3 ice export scenarios were 148 and 169 tg (mt), respectively, with a final average of about 158 tg (mt). discussion fram strait sis provinces versus siberian shelf sediment sources arctic sis are typically much finer grained (i.e., contain more silt and clay) than the circum-arctic shelf source sediments, with a clear emphasis on the 2–63-mm silt fraction (e.g., reimnitz et al. 1998; dethleff 2005; dethleff & kuhlmann 2009). clark & hanson (1983) identified four textural types (type i–iv) of icetransported fine-grained bottom sediment in the arctic ocean (compare figs 2 and 3b), which rely widely on the silt distribution. clark & hanson’s type i represents a non-sorted sediment composition with a rather flat histogram. type ii is a bimodal distribution, with maxima in the fine silt/clay and in the medium silt. type iii represents a distribution with a strong mode in the fine silt and clay sizes, whereas type iv has a pronounced mode in the medium to coarse silt classes. textural types i–iii are related to pack ice rafting (clark & hanson 1983). the general characteristics of the individual sediment types depend on shelf source sediments, hydrodynamics before and during ice entrainment, transport processes, release mechanisms and the depositional environment. detailed granulometric analyses of fram strait sis show that most of the silt fractions match clark & hanson’s (1983) sediment types i, ii and iii (fig. 3b, table 3), which also occur widely on the shelf floors of the kara and laptev seas (fig. 3d, e; table 3). based on table 2 comprehensive sedimentological parameters of fram strait sea-ice sediments (sis) and shelf deposits of the kara and laptev seas. fram sis kara shelf laptev shelf range average sd range average sd range average sd sand (wt%) 0–98.2 7.32 16.54 0.2–33.7 10.80 10.11 2.6–36.0b 12.23b 11.56b silt (wt%) 0.90–75.4 58.99 12.29 46.4–65.4 58.30 6.20 15.0–64.5b 45.37b 16.65b coarse (wt%) 0.2–66.0a 12.92a 14.83a 5.9–50.3 25.16 17.38 13.9–31.6b 23.01b 5.72b medium (wt%) 12.0–41.6a 28.07a 8.94a 24.8–42.5 32.42 6.32 39.8–57.7b 51.29b 6.18b fine (wt%) 10.9–85.5a 59.01a 18.11a 18.8–65.6 42.42 17.03 18.0–36.7b 25.70b 5.91b median (phi) 4.90–8.58a 7.51a 0.78a 5.40–7.91 6.91 0.92 5.89–7.58b 6.67b 0.57b mean (phi) 5.31–8.38a 7.48a 0.68a 5.68–7.81 6.96 0.75 6.04–7.32b 6.71b 0.42b sorting 0.57–1.76a 1.21a 0.28a 0.97–1.89 1.43 0.28 1.20–1.47b 1.32b 0.10b skewness -0.51 to 0.52a -0.06a 0.21a -0.33 to 0.37 0.06 0.22 -0.38 to 0.18b -0.07b 0.20b kurtosis 0.76–2.63a 1.22a 0.45a 0.71–1.05 0.85 0.11 0.69–1.09b 0.84b 0.13b clay (wt%) 0.90–60.0 33.69 13.82 14.0–39.7 30.80 7.04 29.3–53.9b 42.40b 7.75b smectite (%) 0.0–69.0 38.06 20.92 0.0–64.0 38.22 27.53 16.0–66.0 34.36 21.77 illite (%) 13.0–67.0 35.00 16.30 17.0–60.0 32.78 15.66 26.0–49.0 40.36 8.37 kaolinite (%) 2.0–19.0 5.63 2.76 0.0–10.0 4.67 3.65 4.0–25.0 15.73 7.90 chlorite (%) 11.0–33.0 21.52 4.80 12.0–54.0 24.33 15.74 1.0–16.0 9.27 6.30 a without stations a–f. b without stations 8–10. fram strait sea-ice sediment provinces and sourcesd. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 271 ta b le 3 b u lk se d im e n t co m p o si ti o n s, si lt fr ac ti o n at io n s, si lt st at is ti ca lp ar am e te rs , si lt ty p e cl as si fic at io n s, cl ay m in e ra la ss e m b la g e s an d cl ay cl u st e r p ro vi n ce s o f fr am s tr ai t se aic e se d im e n ts (s is ), an d o f sh e lf d e p o si ts fr o m th e k ar a an d la p te v se as . s ta ti o n b u lk (% ) s ilt (% ) s ilt st at is ti cs s ilt ty p e c la y m in e ra lc o m p o si ti o n (% ) c la y cl u st e r s an d s ilt c la y c o ar se m e d iu m fi n e m e d ia n (p h i) m e an (p h i) s o rt in g s ke w n e ss k u rt o si s s m e ct it e ill it e k ao lin it e c h lo ri te fr a m s tr a it s is fr a m s tr a it s is fr a m s tr a it s is fr a m s tr a it s is 1 4 .6 6 9 .8 2 5 .6 2 5 .0 2 6 .4 4 8 .7 7 .4 8 7 .1 5 1 .7 6 -0 .2 0 0 .8 8 i/ ii 5 0 1 9 8 2 3 a 2 3 3 .5 6 3 .6 2 .9 6 6 .0 2 3 .1 1 0 .9 4 .9 0 5 .3 1 1 .3 1 0 .5 2 1 .0 4 iv 5 1 2 6 6 1 7 a 3 2 0 .4 6 2 .0 1 7 .6 5 5 .6 2 2 .5 2 1 .9 5 .3 3 5 .8 7 1 .6 5 0 .4 5 0 .7 8 iv 6 0 1 9 7 1 4 a 4 3 .2 5 7 .3 3 9 .4 9 .4 2 2 .8 6 7 .8 8 .0 0 8 .0 6 1 .4 6 -0 .0 8 1 .3 1 iii 6 5 1 6 4 1 5 a 5 2 .5 7 3 .9 2 3 .6 1 1 .5 2 9 .3 5 9 .2 7 .6 7 7 .8 6 1 .6 3 0 .0 3 1 .1 8 iii 6 0 1 8 3 1 9 a 6 0 .0 5 8 .4 4 1 .6 7 .3 2 1 .3 7 1 .4 7 .8 8 7 .8 2 1 .0 6 -0 .0 9 1 .3 8 iii 6 0 2 0 4 1 6 a 7 0 .0 7 0 .2 2 9 .8 — — — — — — — — — 0 6 7 7 2 6 — 8 0 .0 7 5 .4 2 4 .6 — — — — — — — — — 6 4 5 1 9 3 0 b 9 1 .4 4 4 .6 5 4 .0 6 .1 1 3 .6 8 0 .3 8 .1 0 7 .9 9 1 .0 3 -0 .3 0 1 .6 1 iii 6 3 1 7 4 1 6 a 1 0 0 .1 5 3 .2 4 6 .7 2 .9 2 6 .2 7 0 .9 7 .7 8 7 .7 4 0 .8 8 -0 .1 4 1 .0 7 iii 6 6 1 3 2 1 9 a 1 1 7 .2 5 7 .3 3 5 .5 1 1 .4 3 4 .1 5 4 .5 7 .6 1 7 .4 4 1 .4 4 -0 .1 4 1 .0 2 i/ iii 6 4 1 8 6 1 2 a 1 2 0 .4 3 8 .8 6 0 .8 0 .2 1 2 .0 8 7 .8 8 .2 7 8 .2 2 0 .7 6 -0 .1 1 1 .3 5 iii 5 2 2 2 6 2 0 a 1 3 0 .3 6 3 .4 3 6 .3 6 .2 2 6 .5 6 7 .4 8 .0 2 7 .8 9 1 .0 3 -0 .1 2 1 .0 6 ii/ iii 3 8 2 9 5 2 8 b 1 4 0 .5 5 6 .0 4 3 .5 6 .7 3 3 .4 6 0 .0 7 .6 9 7 .5 5 1 .3 0 -0 .2 3 1 .2 2 iii 3 3 3 8 6 2 3 b 1 5 0 .3 5 6 .9 4 2 .8 1 6 .0 4 0 .1 4 3 .9 7 .1 1 7 .0 0 1 .3 4 -0 .0 9 0 .8 8 i/ iii 1 9 5 2 4 2 5 b 1 6 0 .3 5 5 .9 4 3 .8 1 3 .5 3 8 .3 4 8 .2 7 .2 5 7 .1 2 1 .3 9 -0 .0 8 1 .0 1 i 1 7 5 5 3 2 5 b 1 7 0 .6 5 3 .0 4 6 .4 1 0 .2 3 6 .4 5 3 .4 7 .4 8 7 .3 4 1 .2 0 -0 .0 1 0 .8 1 i 1 5 5 7 4 2 4 b 1 8 0 .2 5 3 .3 4 6 .5 1 0 .0 4 0 .3 4 9 .8 7 .2 8 7 .1 7 1 .1 7 -0 .1 5 0 .7 6 i/ iii 1 3 5 9 3 2 5 b 1 9 1 .0 5 8 .6 4 0 .5 1 4 .6 3 4 .9 5 0 .4 7 .3 8 7 .3 4 1 .2 5 -0 .0 4 1 .6 8 i 1 8 5 3 3 2 6 b 2 0 0 .2 5 8 .1 4 1 .7 9 .6 3 6 .9 5 3 .5 7 .4 3 7 .2 9 1 .1 5 -0 .2 0 2 .0 7 i/ iii 2 7 4 5 4 2 4 b 2 1 0 .8 6 5 .3 3 3 .9 1 1 .2 4 1 .1 4 7 .7 7 .3 6 7 .2 7 1 .2 9 -0 .0 9 0 .8 4 i/ ii 1 3 5 5 5 2 7 b 2 2 0 .0 6 0 .0 4 0 .1 1 0 .6 3 8 .6 5 0 .9 7 .3 5 7 .1 7 1 .3 5 -0 .2 5 0 .9 6 ii 1 1 5 9 3 2 7 b 2 3 4 .0 7 1 .0 2 5 .0 7 .0 4 1 .6 5 1 .4 7 .3 9 7 .4 8 1 .1 1 -0 .0 4 1 .1 0 i/ iii 3 7 3 1 6 2 6 b 2 4 0 .0 6 0 .0 4 0 .0 — — — — — — — — — 4 4 2 7 7 2 2 a 2 5 0 .2 5 8 .5 4 1 .2 2 .8 2 5 .6 7 1 .6 8 .0 3 7 .9 8 1 .0 2 -0 .0 6 1 .0 6 iii 4 4 2 7 6 2 3 a 2 6 1 3 .7 6 4 .7 2 1 .6 3 3 .2 3 3 .8 3 3 .0 6 .3 7 6 .5 3 1 .4 6 0 .1 1 0 .8 1 i/ ii 6 9 2 0 9 1 1 a 2 7 0 .0 6 5 .2 3 4 .8 1 .8 2 3 .0 7 5 .2 7 .8 7 8 .1 0 0 .5 7 0 .4 6 2 .2 4 iii 5 1 2 3 4 2 2 a 2 8 0 .4 4 2 .3 5 7 .3 0 .7 1 2 .0 8 7 .3 8 .2 1 8 .2 0 0 .8 4 0 .0 1 1 .3 0 iii 5 4 2 2 6 1 8 a 2 9 0 .0 6 3 .9 3 6 .1 — — — — — — — — — 4 7 2 7 3 2 3 a fram strait sea-ice sediment provinces and sources d. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd272 3 0 0 .0 4 6 .6 5 3 .4 — — — — — — — — — 5 7 2 2 5 1 6 a 3 1 9 8 .2 0 .9 0 .9 1 1 .6 2 4 .7 6 3 .7 7 .8 3 7 .7 4 1 .1 7 -0 .2 7 1 .1 0 ii/ iii 5 2 2 3 6 1 9 a 3 2 6 .1 6 1 .1 3 2 .8 2 2 .9 2 8 .6 4 8 .5 7 .2 3 6 .9 6 1 .6 5 -0 .1 7 0 .7 7 i/ iii 6 4 1 8 5 1 3 a 3 3 0 .1 6 2 .5 3 7 .5 2 .2 2 3 .4 7 4 .5 8 .5 8 8 .1 7 0 .9 6 -0 .5 1 1 .1 3 iii 5 0 2 6 5 1 9 a 3 4 0 .0 6 6 .1 3 3 .9 1 .0 1 7 .6 8 1 .3 8 .2 8 8 .3 8 1 .2 6 -0 .1 5 1 .6 6 iii 4 6 2 7 6 2 1 a 3 5 0 .0 5 5 .9 4 4 .2 0 .7 1 3 .8 8 5 .5 8 .2 1 8 .2 1 0 .8 6 0 .0 1 2 .6 3 iii 5 7 2 1 5 1 7 a aa 2 0 .0 6 0 .0 2 0 .0 — — — — — — — — — 2 5 4 5 9 2 1 b b a 5 .0 7 0 .0 2 5 .0 — — — — — — — — — 7 6 2 5 2 6 b ca 1 5 .0 7 5 .0 1 0 .0 — — — — — — — — — 1 5 4 8 1 0 2 7 b d a 1 5 .0 7 0 .0 1 5 .0 — — — — — — — — — 1 5 5 5 2 6 b e a 2 5 .0 6 0 .0 1 5 .0 — — — — — — — — — 1 2 5 5 6 2 7 b fa 2 0 .0 6 0 .0 2 0 .0 — — — — — — — — — 1 5 5 4 7 2 4 b k a ra sh e lf k a ra sh e lf k a ra sh e lf k a ra sh e lf 1 2 .7 6 4 .3 3 3 .0 3 7 .1 2 8 .4 3 4 .5 7 .9 1 7 .8 1 1 .5 3 -0 .1 7 0 .8 8 iii 6 2 1 9 7 1 2 a 2 4 .0 5 9 .8 3 6 .2 2 1 .7 3 3 .4 4 4 .9 7 .5 7 7 .5 7 1 .8 9 -0 .0 8 0 .7 8 i 6 2 2 1 5 1 2 a 3 5 .1 6 3 .9 3 1 .0 8 .3 2 6 .1 6 5 .6 6 .7 6 6 .8 0 1 .7 4 0 .1 3 0 .7 1 ii 5 9 2 3 5 1 3 a 4 1 8 .1 5 2 .0 2 9 .9 5 0 .3 2 4 .8 2 5 .0 5 .5 4 5 .9 8 1 .5 7 0 .3 7 0 .7 4 iv 4 9 2 6 1 0 1 5 a 5 4 .2 6 5 .4 3 0 .4 3 5 .5 4 2 .5 2 2 .0 6 .2 1 6 .3 6 1 .4 5 0 .2 2 0 .9 8 i 6 4 1 7 6 1 3 a 6 1 2 .5 6 0 .7 2 6 .8 8 .9 3 6 .7 5 4 .4 7 .7 1 7 .7 6 1 .3 3 0 .1 2 0 .7 7 iii 4 8 2 7 9 1 6 a 7 0 .2 6 0 .1 3 9 .7 5 .9 4 2 .0 5 2 .1 7 .5 2 7 .3 1 0 .9 7 -0 .0 2 0 .8 5 iii 0 6 0 0 4 0 c 8 1 7 .0 4 6 .4 3 6 .6 8 .5 2 6 .9 6 4 .5 7 .6 1 7 .4 0 1 .1 1 -0 .3 3 1 .0 5 iii 0 5 6 0 4 4 c 9 3 3 .7 5 2 .3 1 4 .0 5 0 .2 3 1 .0 1 8 .8 5 .4 0 5 .6 8 1 .2 5 0 .3 3 0 .0 1 iv 0 4 6 0 5 4 c la p te v sh e lf la p te v sh e lf la p te v sh e lf la p te v sh e lf 1 6 .2 6 4 .5 2 9 .3 2 5 .1 5 6 .9 1 8 .0 5 .8 9 6 .0 4 1 .3 4 0 .1 9 0 .8 3 iv 1 6 4 6 2 5 1 3 b 2 3 6 .0 1 5 .0 4 9 .0 3 1 .6 3 9 .8 2 8 .6 7 .5 8 7 .3 2 1 .2 2 -0 .3 8 1 .0 9 iii 1 8 4 6 2 2 1 4 b 3 1 2 .3 3 3 .8 5 3 .9 2 8 .3 4 5 .5 2 6 .2 7 .0 0 6 .8 3 1 .3 7 -0 .1 9 0 .6 9 i 2 2 4 4 2 1 1 3 b 4 2 .6 5 3 .8 4 3 .6 1 3 .9 4 9 .4 3 6 .7 7 .0 2 6 .9 0 1 .2 4 -0 .1 5 0 .9 2 iii 1 8 4 7 1 9 1 6 b 5 3 .7 6 2 .2 3 4 .1 2 3 .1 5 7 .7 1 9 .2 6 .2 1 6 .4 0 1 .4 1 0 .1 8 0 .7 5 ii 2 1 4 4 2 1 1 4 b 6 3 .2 5 3 .1 4 3 .7 2 2 .4 5 4 .6 2 3 .0 6 .3 2 6 .3 7 1 .4 7 0 .0 6 0 .7 0 ii 1 5 4 9 2 2 1 4 b 7 2 1 .6 3 5 .2 4 3 .2 1 6 .7 5 5 .1 2 8 .2 7 .2 7 7 .1 3 1 .2 0 -0 .1 8 0 .8 8 iii 1 6 4 9 2 1 1 4 b 8 b — — — — — — — — — — — — 6 1 3 4 4 1 a 9 b — — — — — — — — — — — — 6 4 2 8 4 1 a 1 0 b — — — — — — — — — — — — 6 1 3 1 7 1 a 1 1 b — — — — — — — — — — — — 6 6 2 6 7 1 a a a re al p e rc e n ta g e e st im at e s fr o m sm e ar sl id e in ve st ig at io n ; 5 0 – 2 0 0 -f o ld b in o cu la r m ag n ifi ca ti o n . b r e w o rk e d af te r d e th le ff e t al . (2 0 0 0 ). fram strait sea-ice sediment provinces and sourcesd. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 273 the clark & hanson (1983) sediment types, we established sis silt provinces in the pack ice of fram strait and north of svalbard. type-i and -ii silts (medium to fine) were more persistent in the western fram strait ice province, whereas the eastern fram strait ice province is instead dominated by type-iii silt (fine). type-iv sis silt (coarse) occurs north-east of svalbard, and is attributed to ice rafting of coarse bottom material, if enhanced sand-sized material coincidently occurs in sis (clark & hanson 1983). this is partly the case northeast of svalbard. figure 4a gives a first indication of the likely origin of fram strait sis from siberian shelf sea bottoms based on silt and clay distributions. as shown in fig. 4a, the western fram strait sis group with laptev bottom sediments, and the eastern fram strait sis cluster with kara sea shelf deposits. from the clark & hanson (1983) silt type classification we conclude that about 50% of the fram strait sis silt samples are less well sorted (types i or ii; see table 3). the silt statistical parameters “sorting” and “mean grain size” (table 3) plotted in fig. 4b support the results of our clark & hanson classification, and show that about 77% of the sis silt fractions are less well or even poorly sorted, and are at the same time extremely fine grained, with a mean grain diameter greater than 6.4 phi (<12 mm; phi = log base 2 scale classifying particle sizes analogous to mm/mm). the same holds true for two-thirds of the kara bottom-surface samples, and for 85% of the eastern laptev sea bottom sediments (western laptev sea bottom silts were not available). plotting “skewness” against “mean grain size” (fig. 4c) corroborates the consistency of the relationship between the extremely fine mean grain diameter (>6.4 phi) and the symmetrical to widely negative skewness of the silt distribution for about 90% of the sis, and for about 50% for the kara and laptev sea silt fractions, respectively. dethleff (2005) stated that about 80% of sis silt samples investigated from the laptev sea, the east siberian sea and the central arctic are symmetrical to widely negatively skewed (fine), and that about 60% are moderately to well sorted. according to the clark & hanson’s (1983) sediment classification, the eastern and central arctic sis correspond to type iii. conversely, in accordance with reimnitz et al. (1998: fig. 5), about 79% of the extremely fine-grained sis samples from the beaufort gyre, with a mean grain diameter greater than 6.4 phi (<12 mm), are symmetrical to widely positively skewed, and about 77% of the samples are very poorly sorted. according to clark & hanson’s (1983) classification, the beaufort gyre sis are of sediment types i and iv. the comparison shows that the beaufort gyre sis samples are potentially somewhat coarser grained in the fine fraction than the siberian sis sample sets. we deduce from the mismatch of skewness between fine-grained sis from the beaufort gyre and from the siberian arctic that silt sediment statistical parameters may help to identify the shelf origin of sis, and conclude that most of the fram strait sis examined in this study originated from siberian shelf sources. looking more closely at the silt fraction, the fram strait sis contained a total average of 89% medium and fine silt in the western part, and more than 92% in the eastern part, with an enhanced fine silt content of ca. 70%. on average, laptev sis and bottom deposits both show the same high abundances of medium and fine silt (ca. 77%; dethleff 2005; this study). dethleff & kuhlmann (2009) also found enhanced medium and fine silt content in the sis of the south-western kara sea, with individual concentrations of more than 84%, which is even higher than the average medium and fine silt content in kara sea shelf surface deposits (ca. 75%) determined in the present study. we conclude that medium to fine silt is entrained into newly forming shelf sea ice in the same percentage as is available on the local bottom (dethleff 2005), or in even higher portions through the preferential collection of angular to subangular discoidal silt particles (dethleff & kuhlmann 2009) in the turbulent process of suspension freezing, particularly driven by langmuir circulation (dethleff et al. 2009). the high medium-to-fine silt content in shelf bottom deposits and shelf sis is also reflected in the fram strait sis. western laptev sea and the kara sea bottom sediments show high contents of smectite, whereas eastern laptev, east siberian and chukchi seas bottom deposits, as well as north american and canadian shelf source sediments, are dominated by illite throughout (wahsner et al. 1999). reimnitz et al. (1998) reported an average table 4 annual sea-ice sediment (sis) flux through fram strait. annual fram strait sis flux (tg/106 t) sis flux (tg/106 t) ice export maximum estimate best estimate minimum estimate average estimate a3300 km3 279 150 78 169 b2900 km3 245 132 68 148 a in 1997 (from vinje 2001). b multidecadal mean (from vinje 2001). fram strait sea-ice sediment provinces and sources d. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd274 sis clay mineral composition of only 9% smectite and 11% kaolinite, but 57% illite and 23% chlorite in the beaufort gyre north of the chukchi and beaufort seas. dethleff (2005) compared the average laptev sea sis clay mineralogy (17% smectite, 44% illite, 25% kaolinite and 14% chlorite) with the sis clay mineral compositions from the reimnitz et al. (1998) study, and concluded that the mismatch between both mineral compositions may be used as a tool to roughly decipher the shelf origin of arctic sis between sources in the eurasian arctic and origins farther east and in the north american arctic. average smectite and illite percentages in sis of western and eastern fram strait show practically inverted values (smectite, 19 versus 56%, 9.0 versus 7.7 sd, table 3, stations 13–23, a–f; illite, 50 versus 21%, 9.3 versus 4.0 sd, table 3, stations 4–6, 9–12 and 24–35), whereas kaolinite and chlorite contents are similar (kaolinite, 5 versus 5%, 2.0 versus 1.6 sd; chlorite, 25 versus 18%, 1.7 versus 3.5 sd). furthermore, the average western fram strait sis smectite and illite contents are very similar to the average laptev sea sis clay values (19 versus 17%, and 50 versus 44%, respectively; compare with dethleff 2005), but the sis of both regions have a clear mismatch in average kaolinite and chlorite percentages (5 versus 25% and 25 versus 14%, respectively). instead, the western fram strait sis have a good match with the beaufort gyre illite and chlorite percentages (50 versus 57% and 25 versus 23%, respectively), but show a mismatch in smectite (19 versus 9%) and kaolinite (5 versus 11%) contents. from the above clay mineral data we assume that the western fram strait pack ice largely contained a mixture of floes originating from the laptev sea region (tpd system) and the north american arctic (beaufort gyre), at least during the years of investigation. conversely, the average eastern fram strait sis clay mineral assemblage shows a significant mismatch with both the laptev sis (dethleff 2005) and the beaufort gyre sis (reimnitz et al. 1998) in smectite, illite and kaolinite contents (smectite, 56 versus 17 versus 9%; illite, 21 versus 44 versus 57%; kaolinite, 5 versus 25 versus 11%), which suggests an sis origin from the westernmost laptev sea and the kara sea shelves, and also potentially from the region around franz josef land, particularly for kaolinite-rich sis (compare with wahsner et al. 1999). to strengthen the identification of potential shelf sources of fram strait sis, the clay mineralogy data from the different regions investigated (fram strait, kara and laptev sea shelves; table 3) were statistically analysed using an mds test assessing the resemblance of bray– curtis similarities between all individual samples. our test results show that all western laptev sea and most kara sea bottom clay compositions cluster with eastern fram strait and northern svalbard sis clays (cluster a; figs. 3b, d, e, 5). this cluster depicts very high average smectite values (>56%), and lower illite concentrations (ca. 23%). bottom clays of the eastern laptev sea cluster with western fram strait sis clays (cluster b) with low fig. 4 (a) groupings of 1997 western and eastern fram strait sea-ice sediments (sis), with the probable siberian shelf source bottom sediments (dark-grey areas). sis station numbers are indicated. diagrams of statistical sis and siberian shelf bottom silt parameters show (b) sorting versus mean grain size, and (c) skewness versus mean grain size. fram strait sea-ice sediment provinces and sourcesd. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 275 average smectite (ca. 18%) and high illite (ca. 49%) contents. cluster c is exclusively related to the western kara sea bay deposits, and has no mineralogical complement in fram strait sis, at least during the seasons investigated. more individual average clay percentages are given in the cluster tables in fig. 5. current entrainment processes and transport of arctic sis campbell & collin (1958) and reimnitz et al. (1993, 1998) introduced the term “suspension freezing” to describe the formation of sediment-laden ice in the turbulent water column. convective winter mixing in shallow open water like flaw leads and polynyas, penetrating down to the arctic shelf, plays a crucial role in fine-grained sediment resuspension on siberian shelves (dmitrenko et al. 2005), and thus in the process of suspension freezing. windand wave-induced langmuir circulation (drucker et al. 2003; dethleff 2005; kempema & dethleff 2006) provide additional momentum to lift resuspended silt and clay particles up into the water column, and promote their incorporation into newly forming ice (dethleff & kempema 2007; dethleff & kuhlmann 2009). the widespread occurrence and persistence of the turbulent process of suspension freezing on the circum-arctic shelves is documented in the prevailing fine-grained composition of sis throughout the arctic. anchor ice also plays a role in arctic sis sediment entrainment (reimnitz et al. 1992; reimnitz et al. 1993), although it produces rather coarse sediment compositions, which we did not observe in our fram strait sis samples. dethleff & kuhlmann (2009) discussed sorting processes and effects of bottom sediments prior to ice entrainment. the authors concluded that in a chain of various hydrodynamic or ice-related processes, the textural imprint of one event (e.g., turbulent resuspension) may be blended with the previous event (e.g., bottom current) and the following event (e.g., sis entrainment), fig. 5 multidimensional scaling test results showing clay clusters a, b and c correlating with fram strait sea-ice sediments (sis) and siberian shelf surface deposits (clusters a and b). cluster-related clay mineral averages and standard deviations are given in the tables within the figure. clay mineral concentrations and correlation coefficients are indicated at the bottom and right-hand side of the figure. fram strait sea-ice sediment provinces and sources d. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd276 potentially resulting in sis of a complex mixed nature. also, secondary reworking of sis through melt cycles may play a role in shaping the composition of ice sediments, although this would lead to scavenging of fine silt and clay particles, and to the enrichment of coarser particles. dethleff & kuhlmann (2009) pointed out that the strength and persistence of bottom currents (e.g., tides) are hydrodynamic features that affect the size distribution of source sediments on the shallow shelf floor before sis entrainment, but that hydrodynamic processes such as langmuir circulation, orbital wave motion and thermohaline convection relate directly to turbulent sediment– ice interaction in the water column, determining the size distribution of the sediments during entrainment into newly forming ice. the generally poor sorting of fram strait sis and the bottom silt of kara and laptev seas reflects the short transport paths of both sediment groups before and during the process of entrainment, or even during melt-related reworking. while bottom silt originates from coastal erosion or local river discharge, sis silt is floated up from the bottom by the process of suspension freezing into newly forming sea ice at depths down to about 40 m. dethleff & kuhlmann (2009) proposed that the latter process is related to a more constant energy level provided by continuous momentum through langmuir circulation and thermohaline convection, as compared with the sea-floor environment during non-entrainment. kempema et al. (1988) stated that sediment-laden sea ice formed in near-shore locations of the beaufort sea could be advected into the arctic basin. reimnitz et al. (1993) quantified the sis export from a beaufort sea polynya to be 0.035 tg (mt) per km of shelf parallel with the coast. eicken et al. (2005) estimated a 5–8 tg (mt) export of sis from the entire chukchi and beaufort shelves for the 2001/02 season, representing a significant term in the sediment budget of the western arctic ocean. eicken et al. (2000) identified an individual sis entrainment and export event of 18.5 tg (mt) from the laptev and east siberian seas close to the new siberian islands in 1994/95, and eicken et al. (1997) and dethleff (2005) quantified the annual sis export from the entire laptev sea to be greater than 20 tg (mt). harms et al. (2000) estimated an annual sis sediment entrainment and export from eastern kara sea flaw leads off the ob and yenisei estuaries of about 2–3 tg (mt). the sis entrainment and export from western kara sea flaw leads was estimated to be about 0.4 tg (mt), whereas the export from the roughly 90-km-long amderma/vaygach lead in the south-west kara sea was expected to be at maximum about 0.077 tg (mt) during the winter of 1996/97 (nies et al. 1998). the above studies point to just a few circum-arctic sis entrainment areas and events investigated and quantified in detail to date. however, more autumn shelf freezing water areas and potential winter polynyas (e.g., dethleff, loewe & kleine 1998: fig. 11; winsor & björk 2000) are available for arctic-wide sis entrainment, which have not been investigated in detail yet. in this context, eicken et al. (2005) made the point that the sis export from the siberian shelf seas is much more important than that of the north american shelves. the transport pathways of arctic sis have been widely identified by simulation, backward trajectory calculations and drift buoy tracks, pointing generally to eurasian shelves as potential source areas (e.g., pfirman et al. 1997; dethleff et al. 1997; dethleff, loewe, weiel et al. 1998; kuhlmann 1998; harms et al. 2000). nürnberg et al. (1994) and dethleff et al. (2000) investigated the mineralogical composition of central arctic sis, which also point to the siberian shelf seas as sources. abelmann (1992) showed that marine/brackish diatom assemblages incorporated in sea ice in the central arctic also indicate initial ice formation on the siberian shelves. darby (2003) found that sea ice formed in the laptev sea is an important factor for basin-wide sediment distribution. all studies show that most of the sis incorporated on the circum-arctic shelves are transported towards fram strait by the tpd. backward-trajectory simulations using the latitude and longitude of present sis fram strait sea-ice sites were conducted with a simulation program provided by the colorado center for astrodynamics research, university of colorado at boulder. the back-trajectory model output widely supports our finding that western fram strait sis corresponds to sources in the eastern laptev sea, and that eastern fram strait sis tracks back to sources in the western laptev and farther west. the model also shows that shelf source regions of fram strait sis may differ from year to year. in this context pfirman et al. (2004) report that the origins of multi-year fram strait sea ice have varied significantly over the past several decades. however, on average—and particularly for the 1996/97 season—the model results of pfirman et al. (2004: fig. 1a, c) perfectly reflect the sis sources and pathways identified in the present study based on sediment statistical analysis. our calculated mean annual sis efflux of 158 tg (mt) through fram strait confirms the magnitude of the annual sis export estimated by larssen et al. (1987; 150 tg [mt]), and our maximum estimate (245–279 tg [mt]) may represent years with extreme sis entrainment events and turbid arctic sea-ice transport like that known from the 1994/95 season in the laptev sea (eicken et al. 2000). however, it is also conceivable that the concenfram strait sea-ice sediment provinces and sourcesd. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 277 trated upper sis layers used in the maximum estimates may reflect a combination of both the “primary” suspension freezing process and the “secondary” reworking within the sea ice in response to albedo-induced melting of sediment-laden ice. this would tend to cause the estimate of the maximum sis export to be somewhat higher than the actual value. nevertheless, the maximum estimate and the observations made by eicken et al. (2000) strengthen the assumption made by dethleff (2005) that a proposed figure of ca. 150 tg (mt) sis annually exported through fram strait is still a too low an estimate. the real figure may be in the magnitude of a quarter billion tonnes—like the maximum estimate in the 1997 season—considering the currently changing general ice situation in the arctic ocean and the changing ice origins and fluxes discussed below. the interannual and interdecadal change of fram strait sea-ice origins (pfirman et al. 2004) both quantitatively influence the overall trans-arctic flux of sis, as sis export from individual circum-arctic shelf seas differ significantly (dethleff & kuhlmann 2009; also see above). however, through the decades the laptev sea shelf is undoubtedly one of the most constant producers of new ice in the arctic, and one of the most constant exporters of sis towards fram strait (dethleff, loewe & kleine 1998; pfirman et al. 2004; dethleff 2005). the laptev sea may control the long-term transpolar sis transport most, but as a consequence this sea is also strongly subjected to coastal erosion (are 1999; rachold et al. 2000; dethleff 2005). future ice situation and sis scenarios in a numerical simulation, holland et al. (2006) showed a potential arctic summer sea-ice decrease to 2 million km2 within a decade, and postulated near ice-free conditions by 2040. however, various current studies on arctic seaice decline show that the interannual reduction of sea-ice extent and thickness is progressing even faster than predicted (e.g., stroeve et al. 2007; haas et al. 2008). nghiem et al. (2007) report a current increase of ice loading into the tpd system accompanied by acceleration of the tpd, thereby exporting excessive ice through fram strait, which might also contribute to the reduction of the perennial ice cover. acceleration of the tpd was also reported by gascard et al. (2008), which was documented by the unusually fast 2000 km transit of the tara ice camp from the northern laptev sea to fram strait, within only 15 months. eicken et al. (2005) proposed a likely increase of sediment-laden sea ice in the chukchi and beaufort seas subsequent to the reduction in summer ice extent, and the related increase of autumn fetch available for initial freezing during the late 1980s and early 1990s. because of the accelerating summer arctic ice retreat, autumn open water on the shallow siberian and north american shelves is even more extended than a decade ago (e.g., nghiem et al. 2007, stroeve et al. 2007; see fig. 1). the significant summer ice retreat provides open-water conditions for sediment entrainment into newly forming frazil and grease ice, in large, shallow shelf areas that have hitherto not been available for new ice formation in late autumn and winter (fig. 1). in general, we expect no major qualitative changes in the nature of sis entrainment processes on the shallow circum-arctic shelves as a result of the reduction of summer ice extent. however, the current increase in autumn shelf fetch related to the late summer ice retreat will cause more extreme wave height and swell on shallow arctic shelves (eicken et al. 2005). this provides momentum for additional sediment mobilization from the shelf bottom (sherwood 2000), and can thus increase the quantity of sediment entrained into newly forming ice. finally, more sediment-laden ice can currently potentially be formed on the circum-arctic shelves during autumn and winter. this, combined with the current acceleration of the tpd, will increase sis transport through the fram strait in the near future. in the event of a completely ice-free arctic ocean in summer by the 2040–2050s (holland et al. 2006), or even by the next decade (maslowski 2008), the arctic ocean will not only entirely lose its role in keeping the north polar region cool and controlling the global climate, but additionally in the more distant future the sis transport by the tpd would be disrupted at least seasonally. if multi-year ice is then completely displaced by first-year ice in the central arctic ocean—a current, dramatic ongoing trend (haas et al. 2008)—sis incorporated in the shallow shelves during the autumn freeze-up and in larger winter flaw leads (eicken et al. 2005) will be released in the central arctic ocean during the next summer melt, and will not reach fram strait. this would lead to a drastically changing sedimentation regime in the central arctic ocean, and to reduced sediment deposition in the north atlantic ocean. conclusions from our investigation of fram strait sis and arctic shelf bottom sediments we conclude the following: • sea ice was generally more turbid in the eastern fram strait than in the western part, and fram strait ice thicknesses increased from east to west. sis was most enhanced in the upper 80-cm part of ice cores, with concentrations of 3 to ca. 300 mg l-1, and showed an fram strait sea-ice sediment provinces and sources d. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd278 absolute maximum of ca. 725 mg l-1. fram strait sis had a lower average sand content than shelf deposits of the kara and laptev seas (<6% versus 11/12%). silt was the dominating fraction in both sis and kara and laptev bottom deposits (average ca. 58 versus 58/45%), whereas clay occurred with ca. 36% (sis) and 31/42% (kara/laptev bottom sediments). the overall qualitative composition of sis and shelf sediments was dominated by similar quartz and feldspar contents. the generally fine-grained texture of fram strait sis was underpinned by enhanced average fine silt content (ca. 59%) and low coarse silt (ca. 13%), whereas the somewhat coarser kara and laptev bottom sediments showed notably enhanced coarse (25/23%) and medium silt fractions (ca. 32/51%). • the silt fractions of sis and kara and laptev bottom deposits match clark & hanson’s (1983) medium to fine-grained types i, ii and iii. based on silt type distribution and clay mineral clusters, we established fram strait sis provinces related to siberian shelf sediment sources. western fram strait sis containing lowsmectite/high-illite composition and medium-to-fine silt correlate with eastern laptev sea shelf deposits, and were also similar to north american arctic shelf source sediments. eastern fram strait sis with high-smectite/ low-illite concentrations and fine silt content relate to western laptev sea and kara sea bottom sediments. we propose that at least during the periods of investigation (1997–99), the western fram strait ice pack consisted of floes originating from the eastern laptev sea and shelf regions east of that (east siberian sea towards north american arctic), and that the eastern fram strait sea ice mainly originated from the western laptev sea and the kara sea. • combining sediment concentrations in fram strait ice cores with annual (1997) and multidecadal ice export rates (vinje 2001), we estimated the potential maximum, best estimate, and minimum sis flux towards the north atlantic. maximum sis flux estimates for annual (3300 km3) and multidecadal (2900 km3) ice export rates showed values of 279 and 245 tg (mt), respectively. the best estimate revealed an sis flux through fram strait of 150 and 132 tg (mt), and the minimum flux amounted to 87 and 68 tg (mt). the overall average estimate of ca. 158 tg (mt) of sis annually fluxing through fram strait is in good agreement with figures proposed in other studies (larssen et al. 1987; dethleff 2005). • present entrainment of sis on circum-arctic shelves is predominantly driven by the process of suspension freezing (turbulent incorporation of fine-grained sediment into newly forming ice in wind-driven open water during the freezing period). we do not expect changes in the process of suspension freezing itself to result from increasing summer arctic ice retreat. however, we anticipate that in the near future more sis will be entrained subsequent to enhanced fetch on the circum-arctic shelves during the start of freezing period, and we presume that there will be increased sis export through fram strait as a result of the acceleration of the tpd. in future, when the perennial pack ice may be completely substituted by first-year ice as a result of an ice-free arctic ocean in summer, all sis entrained on the circum-arctic shelves will be melt-released in the central arctic ocean, and will not reach fram strait or the north atlantic ocean. acknowledgements this study was financially supported by the federal minstry for the environment, nature conservation and nuclear safety, germany (project stsch 4101; 1996-99). the content of this paper does not necessarily reflect the opinion of the ministry. we are indebted to peter loewe, dominik weiel and our russian colleagues from the murmansk marine biological institute for their great help during the kara sea expedition. we are also grateful to dirk nürnberg and erk reimnitz for their help during the laptev sea fieldwork. many helping hands onboard the rv polarstern are thanked for obtaining the sea-ice sediments during the arkxiii/2 and arkxv/3 cruises. we are further indebted to michael levitan from the p.p. shirshov institute of oceanology in moscow for providing sediment samples from the 49th cruise of the rv dmitry mendeleev. moreover, we are grateful to our norwegian colleagues per strand and bjørn lind from the norwegian radiation protection authority, as well as to lars føyn from the institute of marine research, university of bergen, for kindly providing surface sediment samples of the eastern novaya zemlya fjords. we are thankful to amelie winkler for conducting clay mineral analysis of the polarstern arkxv/3 ice sediment samples. dieter piepenburg is thanked for help with the statistical analysis, and we are grateful to ed kempema for reading and improving our manuscript. charles fowler, university of colorado at boulder, provided his simulation program for fram strait sis backward-trajectory calculations. finally, we thank one anonymous reviewer and joseph ortiz for their helpful reviews of the manuscript. references abelmann a. 1992. diatom assemblages in arctic sea ice—indicator for ice drift pathways. deep-sea research part i 39, 525–538. fram strait sea-ice sediment provinces and sourcesd. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 279 are f. 1999. the role of coastal retreat for sedimentation in the laptev sea. in h. kassens et al. (eds.): land–ocean systems in the siberian arctic: dynamics and history. pp. 287–295. berlin: springer. atterberg a. 1912. die mechanische bodenanalyse und die klassifikation der böden mittelschwedens. internationale mitteilungen für bodenkunde. bd. ii. (mechanical soil analysis and classification of the soils of central sweden. international bulletin of soil science. vol. 2.) berlin: verlag für fachliteratur. biscaye p.e. 1965. mineralogy and sedimentation of recent deep-sea clay in the atlantic ocean and the adjacent seas and oceans. geological society of america bulletin 76, 803–832. campbell n.j. & collin a.e. 1958. the discoloration of foxe basin ice. journal of fishery research board canada 15, 1175–1188. clark d.l. & hanson a. 1983. central arctic ocean sediment texture: a key to ice transport mechanisms. in b.f. molina (ed.): glacial-marine sedimentation. pp. 301–330. new york: plenum press. coackley j.p. & syvitski j.p. 1991. sedigraph technique. in j.p. syvitski (ed.): principles, methods and application of particle size analysis. pp. 129–142. cambridge: cambridge university press. colony r. & thorndike a.s. 1985. sea ice motion as a drunkard’s walk. journal of geophysical research—oceans 90, 965–974. darby d.a. 2003. sources of sediment in sea ice from the western arctic ocean, new insights into processes of entrainment and drift patterns. journal of geophysical research—oceans 108, 3257, doi: 10.1029/2002 jc001350. dethleff d. 2005. entrainment and export of laptev sea ice sediments, siberian arctic. journal of geophysical research—oceans 110, c07009, doi: 10.1029/ 2004jc002740. dethleff d. & kempema e.w. 2007. langmuir circulation driving sediment entrainment into newly formed ice—tank experiment results with application to nature (lake hattie, usa; kara sea, siberia). journal of geophysical research—oceans 112, co2004, doi: 10.1029/ 2005jc003259. dethleff d., kempema e., koch r. & chubarenko i. 2009. on the helical flow of langmuir circulation— approaching the process of suspension freezing. cold regions science and technology, doi: 10.1016/ j.coldregions.2008.10.002. dethleff d. & kuhlmann g. 2009. entrainment of fine-grained surface deposits into new ice in the southwestern kara sea, siberian arctic. continental shelf research, doi: 10.1016/j.csr.2008.11.009. dethleff d., kuhlmann g., nürnberg d., harms i.h., karcher m., nies h., rigor i. & shipboard scientific party rv polarstern arkxiii/2. 1997. drift of sediment-laden arctic sea ice— preliminary results from 1997 arkxiii/2 rv “polarstern” cruise and numerical model studies. eos, transactions of the american geophysical union 78. san francisco: american geophysical union. dethleff d., loewe p. & kleine e. 1998. the laptev sea flaw lead—detailed investigation on new ice formation and export during 1991/92 winter season. cold regions science and technology 27, 225–243. dethleff d., loewe p., weiel d., nies h., kuhlmann g., bahe c. & tarasov g. 1998. winter expedition to the southwestern kara sea—investigations on formation and transport of turbid sea-ice. reports on polar research 271. bremerhaven: alfred wegener institute for polar and marine research. dethleff d., nürnberg d., reimnitz e., saarso m. & savchenko y.p. 1993. east siberian arctic region expedition ’92: the laptev sea—its significance for arctic sea ice formation and transpolar sediment flux. reports on polar research 120. bremerhaven: alfred wegener institute for polar and marine research. dethleff d., rachold v., tintelnot m. & antonov m. 2000. sea-ice transport of riverine particles from the laptev sea to fram strait based on clay mineral studies. international journal of earth sciences 89, 496–502. dmitrenko i.a., tyshko k.n., kirillov s.a., eicken h., hölemann j.a. & kassens h. 2005. impact of flaw polynyas on the hydrography of the laptev sea. global and planetary change 48, 9–27. drucker r., martin s. & moritz r. 2003. observations of ice thickness and frazil ice in the st. lawrence island polynya from satellite imagery, upward looking sonar, and salinity/ temperatury moorings. journal of geophysical research—oceans 108, 3149, doi: 10.1029/2001jc001213. eicken h., gradinger r., graves a., mahoney a. & rigor i. 2005. sediment transport by sea ice in the chukchi and beaufort seas: increasing importance due to changing ice conditions? deep-sea research part ii 52, 3281–3302. eicken h., kolatschek j., freitag j., lindemann f., kassens h. & dmitrenko i. 2000. a key source area and constraints on entrainment for basin-scale sediment transport by arctic sea ice. geophysical research letters 27, 1919–1922. eicken h., reimnitz e., alexandrov v., martin t., kassens h. & viehoff t. 1997. sea-ice processes in the laptev sea and their importance for sediment export. continental shelf research 17, 205–233. elverhøi a., pfirman s.l., solheim a. & larssen b.b. 1989. glaciomarine sedimentation in epicontinental seas exemplified by the northern barents sea. marine geology 85, 225–250. folk r.l. & ward w.c. 1957. brazos river bar: a study in the significance of grain size parameters. journal of sedimentary petrology 27, 3–26. gascard j.-c., festy j., le goff h., weber m., bruemmer b., offermann m., doble m., wadhams p., forsberg r., hanson s., skourup h., gerland s., nicolaus m., metaxian j.-p., grangeon j., haapala j., rinne e., haas c., heygster g., jakobson e., palo t., wilkinson j., kaleschke l., claffey k., elder b. & bottenheim j. 2008. exploring arctic transpolar drift during dramatic sea ice retreat. fram strait sea-ice sediment provinces and sources d. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd280 eos, transactions of the american geophysical union 89, 21–28. haas c., pfaffling a., hendricks s., rabenstein l., etienne j.-l. & rigor i. 2008. reduced thickness in arctic transpolar drift favors rapid ice retreat. geophysical research letters 35, l17501, doi: 10.1029/2008gl034457. harms i.h., karcher m.j. & dethleff d. 2000. modeling siberian river runoff—implications for contaminant transport in the arctic ocean. journal of marine systems 27, 95–115. hebbeln d. & wefer g. 1991. effects of ice coverage and ice-rafted material on sedimentation in the fram strait. nature 350, 409–411. holland m.m., bitz c.m. & tremblay b. 2006. future abrupt reductions in the summer arctic sea ice. geophysical research letters 33, l23503, doi: 10.1029/2006gl028024. kempema e.w. & dethleff d. 2006. the role of langmuir circulation in suspension freezing. annals of glaciology 44, 58–62. kempema e.w., reimnitz e. & barnes p.w. 1988. sea ice sediment entrainment and rafting in the arctic. journal of sedimentary petrology 59, 308–317. kern s., harms i., bakan s. & chen y. 2005. a comprehensive view of kara sea polynya dynamics, sea-ice compactness and export from model and remote sensing data. geophysical research letters 32, l15501, doi: 10.1029/2005gl023532. kuhlmann g. 1998. eintrag und transport von sedimenten im arktischen meereis am beispiel der südwestlichen karasee und nördlichen framstraße. (entrainment and transport of sediment in arctic sea ice in the south-western kara sea and northern fram strait). msc thesis, university of kiel. larssen b.b., elverhoi a. & aagaard p. 1987. study of particulate material in sea ice in the fram strait—a contribution to paleoclimate research. polar research 5, 313–315. maslowski w. 2008. when will summer arctic sea ice disappear? paper presented at sustainability weeks 2008— symposium on drastic change in the earth system during global warming, 24 june, sapporo, japan. hokkaido university collection of scholarly and academic papers. martin t. & martin t. 2006. anomalies of sea-ice transports in the arctic. annals of glaciology 44, 310–316. nghiem s.v., rigor i.g., perovich d.k., clemente-colón p., weatherly j.w. & neumann g. 2007. rapid reduction of arctic perennial sea ice. geophysical research letters 34, l19504, doi: 10.1029/2007gl031138. nies h., harms i.h., karcher m.j., dethleff d., bahe c., kleine e., loewe p., oberhuber j.m., kuhlmann g., matishov d., stepanov a. & vasiliev o.f. 1998. anthropogenic radioactivity in the arctic ocean—results of a joint project. german journal of hydrography 50, 313–343. nürnberg d., wollenburg i., dethleff d., eicken h., kassens h., letzig t., reimnitz e. & thiede j. 1994. sediments in arctic sea ice—entrainment, transport and release. marine geology 119, 185–214. osterkamp t.e. & gosink j.p. 1984. observations and analysis of sediment laden sea ice. in p.w. barnes et al. (eds.): the alaska beaufort sea: ecosystem and environment. pp. 73–94. san francisco: academic press. overland j., turner j., francis j., gillett n., marshall g. & tjernström m. 2008. the arctic and antarctic: two faces of climate change. eos, transactions of the american geophysical union 89, 177–184. parkinson c., comiso j.c., zwally h.j., cavalieri d.j., gloersen p. & campbell w.j. 1987. arctic sea ice, 1973–1976: satellite passive-microwave observations. nasa report, special publication sp-489. petschick r., kuhn g. & gingele f.x. 1996. clay mineral distribution in surface sediments of the south atlantic: sources, transport, and relation to oceanography. marine geology 130, 203–229. pfirman s., colony r., nürnberg d., eicken h. & rigor i. 1997. reconstructing the origin and trajectory of drifting arctic sea-ice. journal of geophysical research—oceans 102, 12 575–12 586. pfirman s., haxby w.f., colony r. & rigor i. 2004. variability in arctic sea ice drift. geophysica/research letters 31, l16402, doi: 10.1029/2004gl020063. rachold v., grigoriev m.n., are f.e., solomon s., reimnitz e., kassens h. & antonov m. 2000. coastal erosion vs riverine sediment discharge in the arctic shelf seas. international journal of earth sciences 89, 450–460. reimnitz e., marincovich jr. l., mccormick m. & briggs w.m. 1992. suspension freezing of bottom sediment and biota in the northwest passage and implications for arctic ocean sedimentation. canadian journal of earth sciences 29, 693–703. reimnitz e., mccormick m., bischof j. & darby d.a. 1998. comparing sea-ice sediment load with beaufort sea shelf deposits: is entrainment selective? journal of sedimentary research 68, 777–787. reimnitz e., mccormick m., mcdougall k. & brouwers e. 1993. sediment export by ice rafting from a coastal polynaya, arctic alska, u.s.a. arctic and alpine research 25, 83–98. rigor i. & colony r. 1997. sea-ice production and transport of pollutants in the laptev sea, 1979–1993. science of the total environment 202, 89–110. rothrock d.a. & zhang j. 2005. arctic ocean sea ice volume: what explains its recent depletion? journal of geophysical research—oceans 110, c01002, doi: 10.1029/ 2004jc002282. schauer u. (ed.) 2000. the expedition arktis xv/3 of the research vessel “polarstern” in 1999. reports on polar research 350. bremerhaven: alfred wegener institute for polar and marine research. sherwood c.r. 2000. numerical model of frazil ice and suspended sediment concentrations and formation of sediment laden ice in the kara sea. journal of geophysical research—oceans 105, 14 061–14 080. smedsrud l.h. 2003. formation of turbid ice during autumn freeze-up in the kara sea. polar research 22, 267–286. fram strait sea-ice sediment provinces and sourcesd. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd 281 stein r. & fahl k. (eds.) 1997. scientific cruise report of the arctic expedition ark-xiii/2 of rv “polarstern” in 1997. reports on polar research 255. bremerhaven: alfred wegener institute for polar and marine research. stierle a.p. & eicken h. 2002. sediment inclusions in alaskan coastal sea ice: spatial distribution, interannual variability, and entrainment requirements. arctic, antarctic, and alpine research 34, 465–476. stroeve j.c., serreze m.c., fetterer f., arbetter t., meier w., maslanik j. & knowles k. 2005. tracking the arctic’s shrinking ice cover: another extreme september minimum in 2004. geophysical research letters 32, l04501, doi: 10.1029/2004gl021810. stroeve l., holland m.m., meier w., scambos t. & serreze m. 2007. arctic sea ice decline: faster than forecast. geophysical research letters 34, l09501, doi: 10.1029/ 2007gl029703. tucker m. 1996. methoden der sedimentologie. (methods in sedimentology.) stuttgart: ferdinand enke verlag. vinje t. 2001. fram strait ice fluxes and atmospheric circulation: 1950–2000. journal of climate 14, 3508–3517. vinje t., nordlund n. & kvambekk a. 1998. monitoring ice thickness in fram strait. journal of geophysical research—oceans 103, 10 437–10 449. wahsner m., müller c., stein r., ivanov g., levitan m., shelekova e. & tarasov g. 1999. clay mineral distribution in surface sediments of the eurasian arctic ocean and continental margin as indicator for source areas and transport pathways—a synthesis. boreas 28, 215–233. winsor p. & björk g. 2000. polynya activity in the arctic ocean from 1958 to 1997. journal of geophysical research—oceans 10, 8789–8803. wollenburg i. 1993. sediment transport by arctic sea ice: the recent load of lithogenic and biogenic material. reports on polar research 127. bremerhaven: alfred wegener institute for polar and marine research. zakharov v.f. 1966. the role of flaw leads off the edge of fast ice in the hydrological and ice regime of the laptev sea. oceanology 6, 815–821. fram strait sea-ice sediment provinces and sources d. dethleff & g. kuhlmann polar research 29 2010 265–282 © 2010 the authors, journal compilation © 2010 blackwell publishing ltd282 doi:10.3402/polar.v35.23104 r e s e a r c h / r e v i e w a r t i c l e sedimentary environments in the south-western barents sea during the last deglaciation and the holocene: a case study outside the ingøydjupet trough mauro pau1 & øyvind hammer2 1 physics of geological processes, university of oslo, po box 1048, blindern, no-0316 oslo, norway 2 natural history museum, university of oslo, po box 1172, blindern, no-0318 oslo, norway keywords deglaciation; barents sea ice sheet; sediment cores; lithofacies; biozonation. correspondence mauro pau, physics of geological processes, university of oslo, po box 1048, blindern, no-0316 oslo, norway. e-mail: mauro.pau@fys.uio.no abstract a lithological and foraminiferal study of newly acquired sediment cores outside the ingøydjupet (ingøy deep) trough has been carried out to improve constraints on the last deglacial history in the south-western barents sea. three lithofacies and three foraminiferal facies were identified. the lowermost lithological unit is a diamicton interpreted as glacial till. it contains a lowabundance, ecologically mixed foraminiferal assemblage, presumably resulting from glacial reworking. above the diamicton, a layer of ice-rafted debris (ird), likely associated with intensive iceberg production, marks the initial destabilization of the marine-based ice sheet. at this time, ca. 15.6�15.0 ky b.p., opportunistic foraminiferal species nonionellina labradorica and stainforthia spp. reached peak abundance. during the south-western barents sea ice-margin retreat, presumably corresponding to the bølling interstadial, a sequence of glaciomarine laminations was deposited conformably on the layer of ird. sedimentation rates were apparently high (estimated about 0.4 cm per year) and the foraminiferal fauna was dominated by elphidium spp. and cassidulina reniforme, species common for glacier-proximal environments. a hiatus at the top of the deglacial unit is likely linked to the high bottom-current activity associated with a strengthened inflow of atlantic water masses into the barents sea. the uppermost lithological unit is represented by the holocene marine sandy mud. it contains a high-abundance, high-diversity foraminiferal fauna with common cassidulinids, cibicides spp., epistominella pusilla and planktic species. to access the supplementary material for this article, please see the supplementary file under article tools, online. increasing attention has been paid over the past decade to the dynamics of marine-based ice sheets, which are ice sheets grounded below sea level (e.g., grosfeld & sandhäger 2004; svendsen et al. 2004; heroy & anderson 2007; smith et al. 2011; bigg et al. 2012; hillenbrand et al. 2012). interest stems from the fact that these bodies of ice are inherently unstable; a minor retreat could trigger a destabilization of the entire ice sheet, leading to its collapse (e.g., hughes 2011). two major examples of late quaternary marine-based ice sheets are the barents� kara and the west antarctic ice sheets. at present, collapse of the west antarctic ice sheet threatens to increase global sea levels (joughin & alley 2011 and references therein). in addition, understanding the behaviour of the greenlandic marine-terminating glaciers is of importance for the assessment of future sea level (nick et al. 2009). insights into the dynamics of these modern marine-terminating ice margins can be gained by using the palaeo-ice sheet that covered the barents and kara seas as an analogue (ingólfsson & landvik 2013). polar research 2016. # 2016 m. pau & ø. hammer. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 several studies addressed the issue of defining the extent and timing of the ice sheet in the barents sea region during late weichselian time (e.g., elverhøi et al. 1993; lambeck 1996; landvik et al. 1998; ottesen et al. 2001; olsen 2002; ottesen et al. 2005; sejrup et al. 2005). there is a general agreement that the ice sheet extended to the shelf break along the western barents sea margin (fig. 1) at least twice: before 22 ky b.p. and after 19 ky b.p. (vorren & laberg 1996). the ice-sheet margin then retreated rapidly by iceberg calving within the deeper troughs, which served as outlets for fast-flowing ice streams (vorren & laberg 1996; landvik et al. 1998). the deglaciation was coeval with rising sea level (clark et al. 2009) and was greatly influenced by the influx of atlantic water masses (e.g., chistyakova et al. 2010; junttila et al. 2010). it was, however, punctuated by periods of ice margin stability and readvances, as evidenced by a series of ice-marginal deposits (andreassen et al. 2008; ottesen et al. 2008; winsborrow et al. 2010). the rates of retreat were particularly high in bjørnøyrenna (bear island trough), the largest trough in the western barents sea (fig. 1), where winsborrow et al. (2010) estimate retreat rates of 60�275 m year�1. by 16 ky b.p., bjørnøyrenna was almost entirely ice-free, while by 15 ky b.p. the icesheet margin had retreated onshore in all areas of the western barents sea (winsborrow et al. 2010). this made ice loss by calving no longer possible, and the rate of retreat slowed significantly (winsborrow et al. 2010). the focus of this article is on the last deglaciation of the south-western sector of the barents sea shelf (fig. 1). the glacigenic sediments in this region have been investigated mainly with the aid of twoand three-dimensional seismic data, sub-bottom profiling and/or multibeam bathymetry (vorren & kristoffersen 1986; vorren et al. 1990; andreassen et al. 2008; bellec et al. 2008; ottesen et al. 2008; winsborrow et al. 2010; rebesco et al. 2011; rüther et al. 2011; bjarnadóttir et al. 2012). the studies based on the analysis of sediment cores (hald et al. 1989; ivanova et al. 2002; aagaard-sørensen et al. 2010; chistyakova et al. 2010; junttila et al. 2010) have focused on sites of high sedimentation rate such as the ingøydjupet (ingøy deep) trough (fig. 1). the present work provides new sediment-core data from the area just outside ingøydjupet to better constrain the history of the last deglaciation in the south-western barents sea at shallower water depths. the specific objectives were to (1) fig. 1 regional bathymetry of the south-western barents sea, showing the main troughs and banks (andreassen et al. 2008). also indicated are the approximate locations of the cores used in the present and previous studies. bathymetry from the norwegian hydrographic service (www.mareano. no). abbreviations in this article ct: computerized tomography ird: ice-rafted debris ky b.p.: thousand calendar years before 1950 ms: magnetic susceptibility sem-eds: scanning electron microscopy with energydispersive x-ray spectroscopy si: international system of units sedimentary environments in the south-western barents sea m. pau & ø. hammer 2 (page number not for citation purpose) citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 http://www.mareano.no/ http://www.mareano.no/ http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 identify major lithofacies, (2) distinguish foraminiferal assemblage zones and (3) reconstruct sedimentary environments during and after the last deglaciation. by combining x-ray tomography, gamma density, ms, grain size analysis, sem-eds, biostratigraphy and radiocarbon dating, this study could hold promise for improving constraints on deglacial events in other areas of the barents sea via stratigraphic correlation. data and methods multibeam swath bathymetry of the study area (fig. 2) was acquired by the norwegian defence research establishment in 2009 with a kongsberg maritime em710 multibeam echosounder. the data have a resolution of 1�2 m and 0.1�0.2 m in the horizontal and vertical directions, respectively. four gravity cores (table 1, fig. 2) were collected with the norwegian defence research establishment’s rv h.u. sverdrup ii in 2010. the cores are each 60 mm in diameter and were sampled outside of pockmarks. recovery ranged from 142 to 165 cm. accurate locations of the coring sites were recorded using a hydroacoustic position reference system. lithological analyses included x-ray tomography, gamma density and ms measured with a multi-sensor core logger, coarse grain size (figs. 3, 4), as well as semeds (supplementary fig. s1). x-ray tomography was carried out with a siemens somatom whole-body ct scanner at the norwegian university of life sciences in ås, norway, at a resolution of 1 mm. x-ray density estimated after boespflug et al. (1995) is expressed in ct numbers averaged over the 40 central pixels of the image with a 3-point running average. after splitting, the cores were scanned for gamma ray attenuation and ms (given following si conventions) at the department of earth science, university of bergen, norway, at a resolution of 1 cm. grain size analyses were performed on 5-cm-long sections. the samples were freeze�dried, weighed and wet-sieved at 63 mm. the coarser fraction was dried in an oven at 408c and sieved at 2000 mm. the relative content of gravel (�2000 mm) and sand (63�2000 mm) is given as a dry weight percentage of the total sample weight. sem-eds was performed on a limited number of samples in core lu10-06 at the natural history museum of the university of oslo, norway, in order to investigate the nature of some particles suspected to have ferrimagnetic behaviour. the total number of foraminifera per unit weight of dry sediment was evaluated in core lu10-01 (fig. 5), while the remaining cores were used to estimate relative abundances (figs. 6, 7). benthic foraminifera were counted in the �63 mm fraction for every 5-cm slice of the cores. the fine mesh was used in order not to miss small specimens. however, most of the identified foraminifera are larger than 100 mm, meaning that our results can be compared with those of other studies using larger meshes. the only exception is epistominella pusilla (see taxonomical note and supplementary fig. s2 in the supplementary file), which has a large variation in size including some very small specimens. therefore, previous articles using 100 or 125 mm sieve size may have underestimated its abundance slightly. however, risebrobakken et al. (2010) and chistyakova et al. (2010), using 100 mm sieve size, counted e. pusilla up to 40 and 57%, respectively, in the upper part of their barents sea cores, similar to our numbers. whenever possible, 300 specimens were counted, but in low-abundance samples smaller counts were accepted. relative abundances of the most abundant and/or stratigraphically informative taxa are reported as percentages of the total fauna (fig. 6). a simplified taxonomy was used with 25 taxa identified mainly to the species and genus level. specimens of elphidium were counted as a genus, although several w a te r d e p th ( m ) 100m 375 374 373 372 371 370 369 fig. 2 bathymetry of the study area with the coring sites. see fig. 1 for location in the south-western barents sea. note the occurrence of several pockmarks, appearing as circular depressions (pau et al. 2014). multibeam bathymetry acquired by the norwegian defence research establishment. table 1 length, water depth and position (wgs84) of the lundin petroleum 2010 (lu10) cores. core id length (cm) water depth (m) latitude longitude lu10-01 164 372 728 05.159? n 208 30.714? e lu10-04 165 373 728 05.109? n 208 30.687? e lu10-05 142 371 728 05.107? n 208 31.031? e lu10-06 155 372 728 05.212? n 208 30.402? e m. pau & ø. hammer sedimentary environments in the south-western barents sea citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 species were probably present. an exception was made for the distinct, often very large form e. bartletti. cassidulinids were mostly counted on the family level, but with cassidulina reniforme identified as a separate taxon. the relative abundances of c. neoteretis and islandiella spp. were noted qualitatively. minor taxa not presented here include pullenia bulloides, fissurina sp., lagena spp. (mainly l. distoma), uvigerina sp., lenticulina sp. and bulimina marginata (in some core-bottom samples). most of these taxa were found only in the assemblage zone a (see below), but lagena spp. also occurred in zone c. bulimina marginata was found only in zone c. planktic foraminifera were also counted in the �63 mm fraction. since they were scarce, we merged pairs of samples to obtain acceptable sample sizes (n�30), giving 10-cm vertical resolution. the following forms were counted in core lu10-06 (fig. 7): neogloboquadrina pachyderma, n. incompta, turborotalita quinqueloba, globigerinita uvula and globigerina bulloides. other species of planktic foraminifera were very rare. studies using 100 or 125 mm sieve size may have underestimated the abundance of the relatively small species t. quinqueloba and g. uvula. the biostratigraphic divisions were validated by clustering the foraminiferal assemblages (supplementary fig. s3) using stratigraphically constrained unweighted pair group method with arithmetic mean with the bray�curtis distance measure, in past ver. 3.0 (hammer et al. 2001). fig. 3 ct image, lithological units (dashed lines) and subunits (dotted lines), x-ray and gamma density, ms and grain size (gravel, �2000 mm; sand, 63�2000 mm) for the investigated cores. average ages (ky b.p.) of the dated intervals are indicated. details of the ct images are illustrated in fig. 4. sedimentary environments in the south-western barents sea m. pau & ø. hammer 4 (page number not for citation purpose) citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 seven 14 c radiocarbon dates (table 2) were obtained from macroscopic shell material and collections of foraminifera. the analyses were carried out by means of accelerator mass spectrometry at the radiocarbon dating laboratory of lund university, sweden. the radiocarbon dates were calibrated using the calib v. 7.0 software (stuiver & reimer 2014) with the marine13 calibration curve (reimer et al. 2013), which operates with a standard reservoir correction of 400 years (dr �0). the employed total reservoir age was 467941 years (dr �67941), which is considered representative for the waters off northern norway (mangerud & gulliksen 1975; reimer & reimer 2001). results visually, the sediments appeared as grey mud for most part of the cores, with the top 10�20 cm often showing a brownish colour. the top 1 cm was rich in sponge spicules. gravel particles were occasionally visible and were interpreted as iceberg dropstones. almost no wellpreserved macroscopic shells were encountered. inspection of the ct images revealed significant details of the internal structure of the cores (figs. 3, 4) and provided the basis to identify the lithological units described below. the x-ray and gamma density logs were rather consistent with each other (fig. 3), with density slightly increasing downcore as a result of sediment consolidation. because of variation in the thickness of the split cores, however, the calibrated gamma density values are not considered to be fully reliable. ms (fig. 3) is controlled by density and mineralogy; local variations may therefore be influenced by the content of sand and gravel (a) lu10-01 (b) lu10-04 (c) lu10-05 (d) lu10-06 (e) (f) (g) (h) (i) (j) (k) (l) (m) (n) 0 c o re d e p th ( cm ) c o re d e p th ( cm ) c o re d e p th ( cm ) c o re d e p th ( cm ) 5 10 15 20 30 95 100 105 110 30 35 40 45 50 40 45 50 55 60 35 40 45 50 105 110 115 120 130 135 140 145 130 125 120 115 90 100 105 110 115 120 125 130 135 140 95 100 105 110 0 5 10 15 20 0 5 10 15 20 10 15 20 25 30 fig. 4 detailed views of the ct images: (a�d) holocene marine sediments (lithological unit i); (e�h) glaciomarine laminated sediments (lithological unit ii, subunit iib); (i�l) ird layer (lithological unit ii, subunit iic); (m) and (n) glacial till (lithological unit iii). columns from left to right refer to cores lu10-01, lu10-04, lu10-05 and lu10-06. the yellow line in (c) marks the contact between lithological unit i and the ird layer topping lithological unit ii (subunit iia), while in (e) it marks the erosion surface between subunit iia and the underlying laminations (subunit iib). a b c i ii iii iia iib iic c o re d e p th (c m ) count/gram dry sediment 0 100 200 300 0 20 40 60 80 100 120 140 fig. 5 total number of foraminiferal specimens per unit weight of dry sediment (histogram) in core lu10-01. assemblage zones a, b and c (shades of grey), lithological units i, ii and iii (dashed lines) and lithological subunits iia, iib and iic (dotted lines) are marked. m. pau & ø. hammer sedimentary environments in the south-western barents sea citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 minerals, which possess higher values than clay minerals, and by authigenic formation of ferrimagnetic minerals. lithostratigraphy three lithological units are distinguished based on the ct images, and with the support of the density, grain size and ms logs (figs. 3, 4). lithological unit iii. this unit is observed at the bottom 20�30 cm of cores lu10-01 and lu10-06. the unit appears in the ct images as a diamicton (figs. 3, 4m�n). the coarsest fraction is composed of rounded to angular particles, typically 2�3 cm in size (fig. 4m�n). sand content is around 15%, while ms values are generally lower than 2 �10�4 (fig. 3). lithological unit ii. near the bottom of the unit, a 10-cm-thick layer (subunit iic) is observed with the brightest intensity in the ct images. its depth varies from 98 to 123 cm in the different cores (fig. 4i�l). this layer is dated to 15.6 ky b.p. in core lu10-05, whereas the age i ii i ii iii i ii i ii iii iia iib iic iia iib iic iib iic iia iib iic iia a b a b a lu10-01 lu10-04 lu10-05 a b c c b lu10-06 20 0 20 0 20 0 20 0 40 60 80 100 120 140 200 40 60 0 20 40 60 80 0 10 20 30 0 10 20 30 0 20 40 0 10 20 30 0 10 20 0 10 20 0 5 10 15 0 10 20 30 40 40 60 80 100 120 140 200 40 60 0 20 40 60 80 0 10 20 30 0 10 20 30 0 20 40 0 10 20 30 0 10 20 0 10 20 0 5 10 15 0 10 20 30 40 40 60 80 100 120 140 200 40 60 0 20 40 60 80 0 10 20 30 0 10 20 30 0 20 40 0 10 20 30 0 10 20 0 10 20 0 5 10 15 0 10 20 30 40 40 60 80 100 120 140 200 40 60 0 20 40 60 80 0 10 20 30 0 10 20 30 0 20 40 0 10 20 30 0 10 20 0 10 20 0 5 10 15 0 10 20 30 40 4782 2211 2648 15422 14971 15601 0? elphidium spp. c. reniforme n. labradoricae. pusilla stainforthia spp. cibicides spp. m. barleeanus e. bartletticassidulinids planktic fauna c o re d e p th ( cm ) c o re d e p th ( cm ) c o re d e p th ( cm ) c o re d e p th ( cm ) fig. 6 frequency distribution (%) of the main benthic foraminiferal taxa and the total planktic fauna in the �63 mm fraction in the studied cores. assemblage zones a, b and c (shades of grey), lithological units i, ii and iii (dashed lines) and lithological subunits iia, iib and iic (dotted lines) are marked. ages (ky b.p.) are also indicated. sedimentary environments in the south-western barents sea m. pau & ø. hammer 6 (page number not for citation purpose) citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 obtained just below it in core lu10-04 is 15.0 ky b.p. (slightly overlapping error ranges, table 2). subunit iic has maximal density values and contains a high amount of coarse material, with sand content up to 30�40% and gravel content of over 10% (fig. 3). the coarsest particles reach 3 cm in size (e.g., in core lu10-01, fig. 4i). ms increases up to a peak of about 11 �10�4 in core lu10-05 (fig. 3). further up, lithological unit ii exhibits a 70�80-cmthick layer with laminated sediments (subunit iib), dated to 15.4 ky b.p. in core lu10-01 (table 2). the laminae, deposited in a rhythmic fashion, are about 0.2 cm thick and are formed by brighter fine-sand bands alternating with darker mud bands (figs. 3, 4e�h). a disconformity, illustrated in fig. 4e, separates this laminated sediment from an overlying gravelly layer. rare clasts are present, usually under 1 cm in size (e.g., fig. 4h). sand content, averaged over the muddy and the sandy laminae, does not exceed a few percent (fig. 3). density in unit ii gradually decreases upcore (fig. 3). the ms logs show two distinct, correlatable peaks at ca. 70�80 cm depth in core lu10-04 and around 30�40 cm depth in core lu10-05 (fig. 3). these peaks probably correspond to a single peak just below 70 cm depth in core lu10-01 and at 60 cm depth in core lu10-06 (fig. 3). sem-eds analysis of grainy, black particles with reddish weathering rims found exclusively at these levels (supplementary fig. s1) revealed high abundances of iron and sulphur. the fe:s ratio of 0.75:1 measured on the black particles (supplementary fig. s1b) is consistent with the presence of authigenic greigite (fe3s4), which may form at relatively shallow depths within the sediment in areas where methane hydrates are common (e.g., larrasoaña et al. 2007). the reddish grains (supplementary fig. s1c) exhibit an fe:s ratio of 2:1, probably due to sulphur loss as a result of weathering. at the top of lithological unit ii, a ca. 10-cm-thick layer (subunit iia) is observed with brighter appearance in the ct images, coarser grain size, and slightly enhanced density and ms in comparison with sediments above and below (figs. 3, 4c). the age of 4.8 ky b.p. obtained for this layer from core lu10-01 (table 2) appears anomalously young and is interpreted to originate from a burrowing bivalve. the coarse fraction is generally less abundant than in subunit iic. sand content varies between 10 and 25%, while gravel content is 2�3% (fig. 3). gravel particles of up to 1 cm can be identified in the ct images (for instance, in core lu10-05 below 12 cm core depth, fig. 4c). in core lu10-04, ms shows a peak of over 5 �10�4 (fig. 3). lithological unit i. this unit is found in the top 30�40 cm of most cores (fig. 3). it is composed of homogeneous, somewhat sandy mud with irregular burrows. the age of 2.6 ky b.p. obtained at 15�20 cm depth in core lu10-06 (table 2) dates the unit to the holocene; however, the age of its bottom remains unconstrained. density rapidly decreases upcore in the top ca. 20 cm of the unit. sand content is 15�20% (fig. 3), mostly bioclasts. ms is around 2�3 �10�4, with peaks reaching 6 �10�4 in core lu10-04 and over 15 �10�4 in core lu10-06 (fig. 3). lithological unit i is thinner, about 12 cm, in core lu10-05 (figs. 3, 4c). this is attributed to the vicinity of this site to a pockmark (fig. 2), where the holocene sediment cover is likely to be reduced (chand et al. 2012; pau et al. 2014). lu10-06 a b c 20 0 40 60 80 100 120 c o re d e p th ( cm ) 140 n. incompta t. quinqueloban. pachyderma g. bulloidesg. uvula 0 5 15 0 10 200 20406080 0 204060800 4 8 i ii iii iia iib iic fig. 7 relative abundances of planktic foraminifera in core lu10-06 (percentages of the total planktic fauna). assemblage zones a, b and c (shades of grey), lithological units i, ii and iii (dashed lines) and lithological subunits iia, iib and iic (dotted lines) are marked. fig. 8 biostratigraphic correlations among the cores (solid lines). assemblage zones (a, b and c; shades of grey), lithological units (i, ii and iii; dashed lines) and subunits (iia, iib, and iic; dotted lines) are marked. ages (ky b.p.) are also indicated. m. pau & ø. hammer sedimentary environments in the south-western barents sea citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 biostratigraphy three foraminiferal assemblage zones with relatively sharp boundaries could be defined (figs. 5�8, supplementary fig. s3). total abundance per unit weight of dry sediment generally increases upcore, with higher abundances in zone b than in c, and higher in a than in b (fig. 5). assemblage zone c. this assemblage is found in lithological unit iii. it is characterized by the presence of cassidulinids other than c. reniforme, but in contrast to zone a there is a considerable proportion of islandiella spp. (fig. 6). elphidium spp. and c. reniforme are common, but not as dominant as in zone b. planktic foraminifera are common, with n. pachyderma predominating (�90%, fig. 7). assemblage zone b. this zone is ca. 100 cm thick and is found in lithological unit ii. total foraminiferal abundance per unit weight of dry sediment shows a peak around 70�80 cm depth in core lu10-01 (fig. 5), within subunit iib (laminated package). the zone is marked by the presence of elphidium spp. together with c. reniforme (fig. 6). elphidium is generally dominant and can reach almost 100%, but the top and/or bottom of the zone may also contain peaks of nonionellina labradorica, stainforthia and cibicides. cassidulinids (apart from c. reniforme, fig. 6) and planktic foraminifers (fig. 7) are absent or rare. a sparse planktic fauna dominated by t. quinqueloba is found in the 40�60 cm interval in core lu10-06 (fig. 7). assemblage zone a. this zone is found in lithological unit i, presumably representing the holocene sediment cover. total foraminiferal abundance per unit weight of dry sediment increases suddenly from zone b to zone a (fig. 5). zone a is dominated by epistominella pusilla with subsidiary cibicides spp., cassidulina neoteretis and melonis barleeanus, and abundant planktic foraminifers (fig. 6). elphidium spp. and c. reniforme are notably absent. the fauna is both abundant and species-rich, with minor taxa including stainforthia spp., p. bulloides, fissurina sp., lagena spp. and uvigerina sp. the planktic component is dominated by n. pachyderma, but with n. incompta, t. quinqueloba, g. uvula and g. bulloides also common (fig. 7). sponge spicules can be very abundant, especially in the upper part of the unit. discussion environment prior to the deglaciation the oldest lithological unit encountered (unit iii, figs. 3, 4m, n) is a diamicton and is interpreted as glacial till. this interpretation is supported by the lack of stratification and the quite homogeneous abundance of gravel particles across the cores (licht et al. 1999). the scarcity of datable material did not allow us to obtain a radiocarbon age for the unit, but it must be older than the 15.6 ky b.p. obtained near the base of the overlying lithological unit ii (table 2, fig. 8). the foraminiferal content (zone c, figs. 6, 7) may be glacially reworked. rare bulimina marginata in zone c are opaque and abraded. hald et al. (1990) reported b. marginata at 10�12 m core depth in core 7120/06-01 in the ingøydjupet area, in a clearly disturbed sequence with reversed radiocarbon dates, and interpreted this occurrence as reworked. if in situ, the benthic foraminifera (elphidium and cassidulina reniforme) would likely indicate a glaciomarine setting (see below), while the planktic fauna could be interpreted as full marine but cold water, dominated by neogloboquadrina pachyderma. this diamicton may be correlated with one described from the southern part of ingøydjupet and interpreted as a subglacial till (unit 6, junttila et al. 2010). similar diamictons have been reported elsewhere from the barents sea, and some of them were suggested to have undergone compression by table 2 results from accelerator mass spectrometry 14c radiocarbon dating and calendar (cal.) year calibrations. the error in 14c age (not reservoir corrected) is given as 91s. the analyses were conducted at the radiocarbon dating laboratory, lund university, sweden. the dates were calibrated into calendar years before 1950 (years b.p.) using the marine13 calibration curve (reimer et al. 2013) and are given as 95% confidence intervals. a standard reservoir correction of 400 years with an additional reservoir correction dr � 67941 was employed. core id depth range (cm) material c weight (mg) 14 c age91s (years) cal. age, 2s ranges (years b.p.) cal. age 92s (years b.p.) lu10-01 0�5 astarte sp. 1.74 445950 living? lu10-01 30�40 collection of c. lobatulus 0.54 26159100 2503�1919 22119292 lu10-01 35�40 bivalve debris 0.82 4655950 4969�4595 47829187 lu10-01 55�60 collection of e. bartletti 0.57 13 360975 15 702�15 141 15 4229281 lu10-04 125�135 collection of n. labradorica 0.72 13 120970 15 313�14 629 14 9719342 lu10-05 95�105 collection of n. labradorica 0.66 13 510980 15 913�15 289 15 6019312 lu10-06 15�20 mixed shell fragments 0.31 2985970 2865�2431 26489217 sedimentary environments in the south-western barents sea m. pau & ø. hammer 8 (page number not for citation purpose) citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/23104/0 http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 glacial load (e.g., unit iv, ivanova et al. 2002). unit iii can be related to the stage 1 of the late weichselian events in the south-western barents sea described by winsborrow et al. (2010). this period corresponds to the glacial maximum after 19 ky b.p., with ice streams operating in bjørnøyrenna and other troughs such as ingøydjupet. early deglaciation the beginning of the deglaciation is marked by the deposition of coarse material with abundant gravel particles (�2000 mm) in the 10-cm-thick layer at the bottom of lithological unit ii (subunit iic, figs. 3, 4i�l). this material is interpreted as ird resulting from increased calving of icebergs from the marine ice-sheet margin (aagaard-sørensen et al. 2010), which was mainly triggered by sea-level rise (winsborrow et al. 2010). glacial unloading and rising seawater temperatures during the early deglaciation destabilized methane hydrate deposits, leading to free gas release through the seafloor and the formation of the pockmarks visible in the study area (fig. 2; chand et al. 2012; nickel et al. 2012; pau et al. 2014). during the deposition of subunit iic, nonionellina labradorica reached peak abundance in all cores investigated, marking the base of assemblage zone b (fig. 6). this species often peaks within the later stages of the late weichselian deglaciation in the north-east atlantic (knudsen and austin 1996). another noteworthy foraminifer peaking at the base of zone b is stainforthia (fig. 6). this is a highly opportunistic genus (e.g., alve 2003), often dominating in areas of rapid environmental change. in the arctic region, stainforthia is typically abundant in areas with seasonal sea-ice cover or sea-ice margins (seidenkrantz 2013). the timing of the ird event of subunit iic is constrained between 15.6 and 15.0 ky b.p. (table 2, figs. 3, 8). the age of 15.0 ky b.p. is in line with the results published by pau et al. (2014), who correlate it with the base of lithological unit ii. part of the discrepancy with the age of 15.6 ky b.p. may result from large uncertainty in the radiocarbon calibration curve at the beginning of the bølling warming (reimer et al. 2013) related to rapid and uneven sea-level rise resulting from meltwater pulses (e.g., deschamps et al. 2012). two deglacial ird events were found in ingøydjupet, of which the older one is estimated to have occurred at 15.1 ky b.p. (period i, aagaard-sørensen et al. 2010). this ird event can possibly be correlated with our subunit iic. junttila et al. (2010) report a shift from diamicton to ird abundance in ingøydjupet (units 5 and 4), dating it to 15.0 ky b.p. based on a peak in n. labradorica similar to that found in the present study, chistyakova et al. (2010) estimate the deglaciation to have commenced in ingøydjupet between 14.2 and 13.8 ky b.p. age variations between different sites might reflect a difference in time for the position of the ice margin, but more ages are needed to evaluate this pattern. winsborrow et al. (2010) assign the age of ca. 16 ky b.p. to the onset of glaciomarine conditions in the south-western barents sea (stage 3) and ca. 15 ky b.p. to the complete loss of the ice cover in the region (stage 4). the laminated package immediately above the ird layer (lithological subunit iib, figs. 3, 4e�h) likely documents high sedimentation rates in a glaciomarine environment (e.g., ó cofaigh & dowdeswell 2001 and references therein). the fauna is dominated by elphidium spp., typical of ice-marginal settings, and c. reniforme, a cold-water indicator (fig. 6). furthermore, the absence of planktic foraminifera in the lower part of zone b (figs. 6, 7) is consistent with a glaciomarine environment (see also the barren planktic zone pfz-0 of aagaard-sørensen et al. 2010). the age of 15.4 ky b.p. in the upper part of the laminated sediment (core lu10-01) is within the error range of the age from the preceding ird event in adjacent cores (table 2, figs. 3, 8), possibly in relation to high sedimentation rates. the lamination has a gradational basal contact with the ird layer and is characterized by planar and parallel laminae, occurrence of iceberg dropstones and no bioturbation, probably due to the negative effect of high sedimentation rate on macrofauna (fig. 4e�h). these features correspond to diagnostic criteria for the deposition of laminae by suspensionsettling in an ice-proximal environment (ó cofaigh & dowdeswell 2001). the thickness of the laminae of about 0.2 cm (fig. 4e�h), however, is not high enough to imply a direct proximity to the ice edge (ó cofaigh & dowdeswell 2001). the alternating sand and mud laminae may represent annual couplets reflecting seasonally variable meltwater discharge, in which case they can be classified as glaciomarine varves (ó cofaigh & dowdeswell 2001). a similar interval of laminated sediments is reported from ingøydjupet by aagaardsørensen et al. (2010) and junttila et al. (2010), where the timing of their deposition is related to the older dryas (ca. 14.6�14.5 ky b.p.). in the central part of the barents sea, ivanova et al. (2002) also describe a laminated sequence overlying sediments with abundant ird (unit ii and iii, respectively). they relate the deposition of the laminae to glacier meltwater discharge, following an initial phase of ice-sheet disintegration. the peak in the total number of foraminiferal specimens per unit weight of dry sediment found in zone b of core lu10-01 (fig. 5) could be due to increased m. pau & ø. hammer sedimentary environments in the south-western barents sea citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 foraminiferal productivity along with a local ecological change. since the laminae do not show a decrease in thickness, this peak is not explainable in terms of reduced sedimentation rate. moreover, considering zone b is barren of planktic foraminifera, we cannot relate it to the peak abundance of planktic species found in similar facies by aagaard-sørensen et al. (2010) and junttila et al. (2010). ivanova et al. (2002) report no such peak from the central barents sea either. in core lu10-06, there is an interval near the top of lithological unit ii (40�55 cm core depth, fig. 7) with an initial, moderate influx of planktic foraminifera dominated by the subpolar species t. quinqueloba. this indicates a warmer surface water pulse terminating the glaciomarine environments. for a comparison, in the fram strait area t. quinqueloba predominates close to the seaice margin in water masses influenced by the atlantic water (volkmann 2000). in contrast to a similar, but apparently younger (base holocene) peak of t. quinqueloba found by aagaard-sørensen et al. (2010) in ingøydjupet, the accompanying benthic foraminiferal community (elphidium spp. and c. reniforme) is still distinctly glaciomarine in core lu10-06. moreover, the near-absence of c. neoteretis indicates no considerable atlantic water influence on the benthic fauna at this time. the 63-mm sieve size used in the present study may have enabled detection of this planktic faunal event, which studies based on a larger mesh size (e.g., aagaard-sørensen et al. 2010, 100 mm) would fail to detect. late deglaciation the disconformity at the top of the laminated sediments (fig. 4e) appears to be a result of bottom-current erosion. readvance of grounded ice as an agent of erosion is unlikely, especially in the context of well-preserved pockmarks in the study area (fig. 2). we hypothesize that the intensification of bottom currents was linked to a climatic deterioration and the associated sea-surface cooling and sea-ice formation, hence increased production of brines, possibly during the older dryas (ca. 14.6�14.5 ky b.p.). evidence for intense brine formation in a svalbard fjord coinciding with the older dryas (rasmussen & thomsen 2014) supports this interpretation. the coarse-grained material deposited on top of the disconformity is interpreted as ird (subunit iia, figs. 3, 4e, c). although less prominent than in subunit iic, this ird likely represents a second pulse of enhanced iceberg production from the decaying ice sheet and can be tentatively correlated with the allerød interstadial (ca. 14�13 ky b.p.). both the erosion event and the deposition of subunit iia occurred subsequent to the onshore retreat of the ice margin (winsborrow et al. 2010, stage 4, ca. 15 ky b.p.). no dates are available for the interval contained between 15.0 and 4.8 ky b.p. (table 2), likely indicating a major hiatus at the bottom of the holocene (fig. 4c), probably due to erosion by bottom currents. no such hiatus is reported from ingøydjupet (aagaard-sørensen et al. 2010; chistyakova et al. 2010; junttila et al. 2010); nonetheless, the authors provide micropaleontological evidence for high-energy bottom environments in the early holocene (aagaard-sørensen et al. 2010; chistyakova et al. 2010). the difference in water depth between the present study area and ingøydjupet corresponds to about 50 m, suggesting topography-controlled local variations in the hydrodynamic regime. aagaard-sørensen et al. (2010) and chistyakova et al. (2010) link the increased bottom-current activity to a strengthening of the atlantic current, consistent with a regional trend for the barents sea (hald et al. 2007; risebrobakken et al. 2010). near the boundary between assemblage zones a and b, the investigated cores exhibit intermittent absence of planktic foraminifera, together with a very lowabundance benthic fauna. this thin, barren interval could possibly reflect the younger dryas cold event dated in ingøydjupet to 12.70�11.65 ky b.p. by aagaardsørensen et al. (2010) and to 12.8�11.3 ky b.p. by chistyakova et al. (2010). late holocene the holocene sedimentary record recovered is characterized by deposition of marine mud with an abundant bioclastic component (lithological unit i, figs. 3, 4a�d). the earliest date that can be provided for the holocene material is 4.8 ky b.p. (table 2). this age, obtained on fragments of a thin-shelled bivalve from the top of the underlying assemblage zone b (fig. 8), presumably represents the age for the bottom of zone a as bivalves may move vertically up to a few tens of centimetres in their burrow. mixed shell fragments recovered from the middle of lithological unit i/assemblage zone a are of late holocene age (2.6 ky b.p., table 2, figs. 3, 6, 8). the hiatus between units ii and i is marked by a relatively abrupt change in the taxonomic composition of the foraminiferal assemblage, accompanied by a significant increase in the species richness and abundance (assemblage zone a, figs. 5�7). the latter is explainable in terms of reduced sedimentation rate in the holocene, and probably also downcore dissolution of the carbonate sedimentary environments in the south-western barents sea m. pau & ø. hammer 10 (page number not for citation purpose) citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 tests. the abundance of planktic foraminifers (figs. 6, 7) indicates full marine conditions. the increased influence of atlantic water is illustrated by a common occurrence of cassidulina neoteretis (mackensen & hald 1988). furthermore, high abundance of cibicides spp., with a peak dated to ca. 2.2 ky b.p. in one of the cores (table 2, fig. 6), suggests high bottom-current velocities. a similar faunal change, found elsewhere in the western barents sea, has been explained by the influence of atlantic water masses and increased bottom currents (ivanova et al. 2002; aagaard-sørensen et al. 2010; chistyakova et al. 2010). the topmost 20�30 cm interval in some cores under this study is characterized by a reduction in c. neoteretis, with epistominella pusilla becoming dominant, reaching 70% at the core top. a similar development in benthic foraminifers during the holocene was noted in ingøydjupet by chistyakova et al. (2010). the increase of e. pusilla reflects warm atlantic water, increasing bottom currents and unstable flux of organic matter to the seafloor (rasmussen et al. 2007; chistyakova et al. 2010). conclusions based on a lithological and foraminiferal investigation of sediment cores retrieved in the south-western barents sea, three lithofacies and associated foraminiferal assemblage zones were identified. this stratigraphy represents a transition from subglacial to glaciomarine and marine depositional environments. based on the available 14 c ages, deglaciation of the study area began prior to ca. 15.6�15.0 ky b.p. an ird layer was deposited during the initial disintegration of the ice sheet, possibly corresponding to the inception of the bølling interstadial. overlying laminated glaciomarine sediments were likely deposited in proximity to the retreating ice-sheet margin. a major depositional hiatus, loosely bracketed by the ages of 15.0 and 4.8 ky b.p., separates deglacial and holocene sediments. the hiatus presumably indicates high bottomcurrent activity, probably linked to a strengthening of the inflow of atlantic water into the barents sea with the onset of holocene environments. acknowledgements harald brunstad and lundin petroleum norway are warmly thanked for financial support and for providing the cores. for the excellent support during the expedition, a sincere gratitude goes to arnfinn karlsen, helge jubskås, martin syre wiig, kjetil bergh ånonsen and jon otto buer from the norwegian defence research establishment, as well as to the officers and crew of rv h.u. sverdrup ii, johnny remøy (captain), terje haugen, erling olsen, henning bergsnes, john johnsen, bernt nilsen and liv sørensen. arnfinn karlsen is thanked also for the logistical assistance. haflidi haflidason at the university of bergen is gratefully acknowledged for the assistance with core logging. knut dalen at the norwegian university of life sciences is thanked for assistance with ct scanning, and mufak naoroz at the university of oslo for support with grain size analysis. the article benefited from comments and suggestions by leonid polyak and other reviewers. references aagaard-sørensen s., husum k., hald m. & knies j. 2010. paleoceanographic development in the sw barents sea during the late weichselian�early holocene transition. quaternary science reviews 29, 3442�3456. alve e. 2003. a common opportunistic foraminiferal species as an indicator of rapidly changing conditions in a range of environments. estuarine, coastal and shelf science 57, 501�514. andreassen k., laberg j.s. & vorren t.o. 2008. seafloor geomorphology of the sw barents sea and its glaci-dynamic implications. geomorphology 97, 157�177. bellec v., wilson m., bøe r., rise l., thorsnes t., buhlmortensen l. & buhl-mortensen p. 2008. bottom currents interpreted from iceberg ploughmarks revealed by multibeam data at tromsøflaket, barents sea. marine geology 249, 257�270. bigg g.r., clark c.d., greenwood s.l., haflidason h., hughes a.l.c., levine r.c., nygård a. & sejrup h.p. 2012. sensitivity of the north atlantic circulation to break-up of the marine sectors of the nw european ice sheets during the last glacial: a synthesis of modelling and palaeoceanography. global and planetary change 98/99, 153�165. bjarnadóttir l.r., rüther d.c., winsborrow m.c.m. & andreassen k. 2012. grounding-line dynamics during the last deglaciation of kveithola, w barents sea, as revealed by seabed geomorphology and shallow seismic stratigraphy. boreas 42, 84�107. boespflug x., long b.f.n. & occhietti s. 1995. cat-scan in marine stratigraphy: a quantitative approach. marine geology 122, 281�301. chand s., thorsnes t., rise l., brunstad h., stoddart d., bøe r., lågstad p. & svolsbru t. 2012. multiple episodes of fluid flow in the sw barents sea (loppa high) evidenced by gas flares, pockmarks and gas hydrate accumulation. earth and planetary science letters 331/332, 305�314. chistyakova n.o., ivanova e.v., risebrobakken b., ovsepyan e.a. & ovsepyan y.s. 2010. reconstruction of the postglacial environments in the southwestern barents sea based on foraminiferal assemblages. oceanology 50, 573�581. m. pau & ø. hammer sedimentary environments in the south-western barents sea citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 clark p.u., dyke a.s., shakun j.d., carlson a.e., clark j., wohlfarth b., mitrovica j.x., hostetler s.w. & mccabe a.m. 2009. the last glacial maximum. science 325, 710�714. deschamps p., durand n., bard e., hamelin b., camoin g., thomas a.l., henderson g.m., okuno j. & yokoyama y. 2012. ice-sheet collapse and sea-level rise at the bølling warming 14,600 years ago. nature 483, 559�564. elverhøi a., fjeldskaar w., solheim a., nyland-berg m. & russwurm l. 1993. the barents sea ice sheet*a model of its growth and decay during the last ice maximum. quaternary science reviews 12, 863�873. grosfeld k. & sandhäger h. 2004. the evolution of a coupled ice shelf�ocean system under different climate states. global and planetary change 42, 107�132. hald m., andersson c., ebbesen h., jansen e., klitgaardkristensen d., risebrobakken b., salomonsen g.r., sarnthein m., sejrup h.p. & telford r.j. 2007. variations in temperature and extent of atlantic water in the northern north atlantic during the holocene. quaternary science reviews 26, 3423�3440. hald m., danielsen t.k. & lorentzen s. 1989. late pleistocene� holocene benthic foraminiferal distribution in the southwestern barents sea: paleoenvironmental implications. boreas 18, 367�388. hald m., sættem j. & nesse e. 1990. middle and late weichselian stratigraphy in shallow drillings from the southwestern barents sea: foraminiferal, amino acid and radiocarbon evidence. norwegian journal of geology 70, 241�257. hammer ø., harper d.a.t. & ryan p.d. 2001. past: paleontological statistics software package for education and data analysis. palaeontologia electronica 4(1), article no. 4. heroy d.c. & anderson j.b. 2007. radiocarbon constraints on antarctic peninsula ice sheet retreat following the last glacial maximum (lgm). quaternary science reviews 26, 3286�3297. hillenbrand c.-d., melles m., kuhn g. & larter r.d. 2012. marine geological constraints for the grounding-line position of the antarctic ice sheet on the southern weddell sea shelf at the last glacial maximum. quaternary science reviews 32, 25�47. hughes t. 2011. a simple holistic hypothesis for the selfdestruction of ice sheets. quaternary science reviews 30, 1829�1845. ingólfsson ó. & landvik j.y. 2013. the svalbard�barents sea ice-sheet*historical, current and future perspectives. quaternary science reviews 64, 33�60. ivanova e.v., murdmaa i.o., duplessy j.-c. & paterne m. 2002. late weichselian to holocene paleoenvironments in the barents sea. global and planetary change 34, 209�218. joughin i. & alley r.b. 2011. stability of the west antarctic ice sheet in a warming world. nature geoscience 4, 506�513. junttila j., aagaard-sørensen s., husum k. & hald m. 2010. late glacial�holocene clay minerals elucidating glacial history in the sw barents sea. marine geology 276, 71�85. knudsen k.l. & austin w.e.n. 1996. late glacial foraminifera. in j.t. andrews et al. (eds.): late quaternary palaeoceanography of the north atlantic margin. pp. 7�10. london: the geological society. lambeck k. 1996. limits on the areal extent of the barents sea ice sheet in late weichselian time. global and planetary change 12, 41�51. landvik j.y., bondevik s., elverhøi a., fjeldskaar w., mangerud j., salvigsen o., siegert m.j., svendsen j.-i. & vorren t.o. 1998. the last glacial maximum of svalbard and the barents sea area: ice sheet extent and configuration. quaternary science reviews 17, 43�75. larrasoaña j.c., roberts a.p., musgrave r.j., gràcia e., piñero e., vega m. & martı́nez-ruiz f. 2007. diagenetic formation of greigite and pyrrhotite in gas hydrate marine sedimentary systems. earth and planetary science letters 261, 350�366. licht k.j., dunbar n.w., andrews j.t. & jennings a.e. 1999. distinguishing subglacial till and glacial marine diamictons in the western ross sea, antarctica: implications for a last glacial maximum grounding line. geological society of america bulletin 111, 91�103. mackensen a. & hald m. 1988. cassidulina teretis tappan and c. laevigata d’orbigny: their modern and late quaternary distribution in the northern seas. journal of foraminiferal research 18, 16�24. mangerud j. & gulliksen s. 1975. apparent radiocarbon ages of recent marine shells from norway, spitsbergen and arctic canada. quaternary research 5, 263�273. nick f.m., vieli a., howat i.m. & joughin i. 2009. large-scale changes in greenland outlet glacier dynamics triggered at the terminus. nature geoscience 394, 110�114. nickel j.c., di primio r., mangelsdorf k., stoddart d. & kallmeyer j. 2012. characterization of microbial activity in pockmark fields of the sw-barents sea. marine geology 332�334, 152�162. ó cofaigh c. & dowdeswell j.a. 2001. laminated sediments in glacimarine environments: diagnostic criteria for their interpretation. quaternary science reviews 20, 1411�1436. olsen l. 2002. mid and late weichselian, ice-sheet fluctuations northwest of the svartisen glacier, nordland, northern norway. geological survey of norway bulletin 440, 39�52. ottesen d., dowdeswell j.a. & rise l. 2005. submarine landforms and the reconstruction of fast-flowing ice streams within a large quaternary ice sheet: the 2500-km-long norwegian�svalbard margin (578�808 n). geological society of america bulletin 117, 1033�1050. ottesen d., rise l., rokoengen k. & sættem j. 2001. glacial processes and large-scale morphology on the mid-norwegian continental shelf. in o.j. martinsen & t. dreyer (eds.): sedimentary environments offshore norway*palaeozoic to recent. pp. 439�447. amsterdam: elsevier. ottesen d., stokes c.r., rise l. & olsen l. 2008. ice-sheet dynamics and ice streaming along the coastal parts of northern norway. quaternary science reviews 27, 922�940. pau m., hammer ø. & chand s. 2014. constraints on the dynamics of pockmarks in the sw barents sea: evidence from gravity coring and high-resolution, shallow seismic profiles. marine geology 355, 330�345. sedimentary environments in the south-western barents sea m. pau & ø. hammer 12 (page number not for citation purpose) citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 rasmussen t.l. & thomsen e. 2014. brine formation in relation to climate changes and ice retreat during the last 15,000 years in storfjorden, svalbard, 76�788n. paleoceanography 29, 911�929. rasmussen t.l., thomsen e., slubowska m.a., jessen s., solheim a. & koc n. 2007. paleoceanographic evolution of the sw svalbard margin (768n) since 20,000 14c yr bp. quaternary research 67, 100�114. rebesco m., liu y., camerlenghi a., winsborrow m., laberg j.s., caburlotto a., diviacco p., accettella d., sauli c., wardell n. & tomini i. 2011. deglaciation of the western margin of the barents sea ice sheet*a swath bathymetric and sub-bottom seismic study from the kveithola trough. marine geology 279, 141�147. reimer p.j., bard e., bayliss a., beck j.w., blackwell p.g., bronk ramsey c., buck c.e., cheng h., edwards r.l., friedrich m., grootes p.m., guilderson t.p., haflidason h., hajdas i., hatté c., heaton t.j., hoffmann d.l., hogg a.g., hughen k.a., kaiser k.f., kromer b., manning s.w., niu m., reimer r.w., richards d.a., scott e.m., southon j.r., staff r.a., turney c.s.m. & van der plicht j. 2013. intcal13 and marine13 radiocarbon age calibration curves, 0�50,000 years cal bp. radiocarbon 55, 1869�1887. reimer p.j. & reimer r.w. 2001. a marine reservoir correction database and on-line interface. radiocarbon 43, 461�463. risebrobakken b., moros m., ivanova e.v., chistyakova n. & rosenberg r. 2010. climate and oceanographic variability in the sw barents sea during the holocene. the holocene 20, 609�621. rüther d.c., mattingsdal r., andreassen k., forwick m. & husum k. 2011. seismic architecture and sedimentology of a major grounding zone system deposited by the bjørnøyrenna ice stream during late weichselian deglaciation. quaternary science reviews 30, 2776�2792. seidenkrantz m.-s. 2013. benthic foraminifera as palaeo seaice indicators in the subarctic realm*examples from the labrador sea�baffin bay region. quaternary science reviews 79, 135�144. sejrup h.p., hjelstuen b.o., dahlgren k.i.t., haflidason h., kuijpers a., nygård a., praeg d., stoker m.s. & vorren t.o. 2005. pleistocene glacial history of the nw european continental margin. marine and petroleum geology 22, 1111�1129. smith j.a., hillenbrand c.-d., kuhn g., larter r.d., graham a.g.c., ehrmann w., moreton s.g. & forwick m. 2011. deglacial history of the west antarctic ice sheet in the western amundsen sea embayment. quaternary science reviews 30, 488�505. stuiver m. & reimer p.j. 2014. calib 7.0. accessed on the internet at http://calib.qub.ac.uk/calib/ on 31 january 2014. svendsen j.i., alexanderson h., astakhov v.i., demidov i., dowdeswell j.a., funder s., gataullin v., henriksen m., hjort c., houmark-nielsen m., hubberten h.w., ingólfsson ó., jakobsson m., kjær k.h., larsen e., lokrantz h., lunka j.p., lysa a., mangerud j., matiouchkov a., murray a., möller p., niessen f., nikolskaya o., polyak l., saarnisto m., siegert c., siegert m.j., spielhagen r.f. & stein r. 2004. late quaternary ice sheet history of northern eurasia. quaternary science reviews 23, 1229�1271. volkmann r. 2000. planktic foraminifers in the outer laptev sea and the fram strait*modern distribution and ecology. journal of foraminiferal research 30, 157�176. vorren t.o. & kristoffersen y. 1986. late quaternary glaciation in the south-western barents sea. boreas 15, 51�59. vorren t.o. & laberg j.s. 1996. late glacial air temperature, oceanographic and ice sheet interactions in the southern barents sea region. in j.t. andrews et al. (eds.): late quaternary palaeoceanography of the north atlantic margin. pp. 303�321. london: the geological society. vorren t.o., lebesbye e. & larsen k.b. 1990. geometry and genesis of the glacigenic sediments in the southern barents sea. in j.a. dowdeswell & j.d. scourse (eds.): glacimarine environments: processes and sediments. pp. 269�288. london: the geological society. winsborrow m.c.m., andreassen k., corner g.d. & laberg j.s. 2010. deglaciation of a marine-based ice sheet: late weichselian palaeo-ice dynamics and retreat in the southern barents sea reconstructed from onshore and offshore glacial geomorphology. quaternary science reviews 29, 424�442. m. pau & ø. hammer sedimentary environments in the south-western barents sea citation: polar research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.23104 13 (page number not for citation purpose) http://calib.qub.ac.uk/calib/ http://www.polarresearch.net/index.php/polar/article/view/23104 http://dx.doi.org/10.3402/polar.v35.23104 the diet of high-arctic seabirds in coastal and ice-covered, pelagic areas near the svalbard archipelago f. mehlum and g. w. gabrielsen mehlum, f. & gabrielsen, g. w. 1993: the diet of high-arctic seabirds in coastal and ice-covered, pelagic areas near the svalbard archipelago. polar research 12(1), 1-20. food samples from six high-arctic seabird species were collected during spring and summer seasons between 1982 and 1990 in the svalbard region. the material came from coastal localities on the island of spitsbergen and the marginal ice zone in eastern svalbard waters. polar cod boreogadus saida was the most frequently occurring prey in the ice-covered areas. analysis of otoliths showed that most polar cod were oneor two year olds. these year classes are known to associate with sea ice. other ice-associated (sympagic) organisms, such as gammarid amphipods, were not found to be of high importance as prey for seabirds in the study area. however, the sea ice occurring in the area was mainly one year old. such ice contains a less developed sympagic fauna than multi-year ice. the pelagic amphipod parathemisto libellula, which is not sympagic but occurs in the water column, was also found to be an important prey in the marginal ice zone, especially for the briinnich’s guillemot uria lomuia. the smallest of the seabird species studied, the little auk alle alle, differed from the other five species in its diet, preying mainly upon smaller items such as copepods and young stages of amphipods, euphausiids and decapods. the diet of the various seabird species was in general more diverse in the coastal areas than in the marginal ice zone. f. mehlum and g. w. gabrieken., norwegian polar institute, p.o. box 5072 majorstua, n-0301 oslo, norway. introduction the waters around the svalbard archipelago sup port large populations of several species of sea birds (mehlum 1989; mehlum & bakken in press). these populations consume a variety of marine organisms. there is little knowledge avail able about the impact of the seabirds on the marine ecosystem in this part of the arctic and the functional role of seabirds in the ecosystem as predators on marine organisms. the diets of seabirds in ice-covered, pelagic and coastal areas around the svalbard archipelago and the northern barents sea have not previously been studied in detail. a general review of the available infor mation up to 1959 is given by lavenskiold (1964). the most comprehensive published studies of sea bird diets in coastal parts of the svalbard area are those by hartley & fisher (1936) and lydersen et al. (1989). some preliminary results of parts of our own studies have been published elsewhere (mehlum & gjertz 1984; gjertz et al. 1985; mehlum 1990). several authors have recently emphasised the importance of ice-edges and the marginal ice zone in polar seas as foraging areas for seabirds (see hunt 1991 for review). these habitats are abun dant in the waters near svalbard and may be crucial for the subsistence of the seabirds in this area. in the ice-related habitats seabirds may exploit the pelagic zooplankton and fish species as well as the fauna associated with the under-ice surface (sympagic fauna), dominated by gamma rid amphipods and young polar cod boreogadus saida (bradstreet 1980). this paper describes the diet of seabirds in the svalbard area during spring and summer seasons between 1982 and 1990. we present analyses of foods found in the stomachs of six species of seabirds: northern fulmar fulmarus glacialis, black-legged kittiwake rissa tridacfyla, ivory gull pagophila eburnea, briinnich’s guillemot uria lomuia, black guillemot cepphus grylle, and little auk alle alle. all seabird species except the ivory gull were collected both in coastal areas with no sea ice and in the marginal ice zone in the northern barents sea. the ivory gull was collected only in the marginal ice zone. three of these species are surface feeders and three pursuit diving sub surface feeders. in particular, we wanted t o inves tigate the importance of fauna associated with the sea ice subsurface to seabirds foraging in the marginal ice zone, and to compare the diets of present address: norwegian institute for nature research, c/o troms0 museum, n-9ooo troms), norway. 2 f. mehlum & g . w . gabrielsen b j ~ ~ r n ~ j y a 0 birds foraging in coastal versus ice-covered, pel agic areas. 0 a u g . 1 9 8 2 0 j u l y / a u g . 1 9 8 4 + apr./may 1 9 8 5 4 may/june 1 9 8 6 rn febr./march 1 9 8 7 v a u g . 1 9 8 7 physical and biological setting seabirds are present in the svalbard region all year, both in water areas that are open and partly ice-covered, but the number of individuals in the area are highest in the summer months. fulmars and several species of alcids and larids breed on steep cliffs along the coasts. the largest colonies are found in the northwestern, southwestern and southeastern parts of the archipelago, including the two islands, hopen and bj~rnbya (bear island) (fig. 1). the svalbard archipelago is located north of the shallow and productive barents sea. these islands, except for b j ~ m ~ y a (74”30‘n), are located between 76 to 81 degrees north latitude (fig. 1). they experience a high-arctic climate, with maximum mean summer temperatures reaching 45°c. despite the extreme northern location, the area is one of the most easily access ible for seabirds of the high arctic. this is pri marily due to the presence of open water during 0 0 0 0 kongs fjorden q det 0 m northern b a r e n t s sea 4 rn hopen 5 0 0 4 m o o 6 0 0 20 00 26 00 s o 0 0 5 6 0 0 4000 fig. 1. sketch map of the study area and locations of sampling, stations. diet of high-arctic seabirds 3 species are shown in table 1. most seabirds were collected at sea. all specimens shot were fully grown individuals if not otherwise indicated. actively feeding birds were preferred, but most of the specimens were collected while flying. within 30min after being shot, the birds were placed whole in a deep-freeze, or the stomachs and esophagus tracts were removed and either stored in a deep-freeze or preserved in 70% ethanol. food samples from kittiwakes at breeding col onies in the kongsfjorden area were collected by catching adults and chicks on the nests and inducing the birds to regurgitate their food into plastic bags. similarly, chick-feeding little auks in the hornsund and isfjorden areas were captured upon returning to their nests and their sublingual pouches were emptied and the contents placed in plastic bags. these samples were placed in a deep freeze (-20°c). a third method of collecting data, used in 1989 at kovalskifjellet in storfjor den, was direct observation of food brought by parents of young brunnich's guillemots to the breeding ledges. the primary prey brought to the young were fish, and the different taxa could be determined in most instances (96%). a large part of the year, especially in the western parts of the archipelago. throughout the year, a branch of the north atlantic current transports enormous masses of relatively warm water north wards into the barents sea and along the western coasts of svalbard (loeng 1989). these water masses mix with the cold polar water, and in the frontal areas a rich marine production occurs (loeng 1989). the resultant large biomass of pelagic invertebrates and fish provides the food basis for the seabird populations inhabiting the area. the extent of the ice cover in these waters varies from year to year and at different times of the year (vinje 1985). marginal ice zones are very productive areas due to high levels of inorganic nutrients and little vertical mixing of near surface water (sakshaug & skjoldal 1989). the phyto plankton bloom is grazed by copepods and other zooplankters, which in turn provide food for larger organisms such as fish and seabirds. during the spring and summer seasons, the productive areas gradually recede northwards with the mar ginal ice zone. materials and methods data collection the sampling periods, geographical areas and the numbers of samples obtained from each seabird data analyses for identification of prey, the stomach contents were first washed into a 0.5 mm sieve. all items were then sorted to the lowest possible taxon using available keys and, when possible, reference table 1. sampling localities, month/year, and sample sizes of six species of seabirds. only birds containing identifiable prey taxa are included. locality/month/year briinnich's black fulmar kittiwake ivory gull guillemot guillemot little auk n = 5 0 n = 1 2 3 n = 1 9 n = 276 n = 73 n = 178 marginal ice-zone svalbard e, aug. 19x2 svalbard e, july/aug. 1984 svalbard e, apr./may 1985 svalbard e, may/june 1986 svalbard e. febr./march 1987 svalbard e. aug. 1987 coastal areas kongsfjorden, july 1982/83 kongsfjorden, june 1984 kongsfjorden, june/july 1985 kongsfjorden, july/aug. 1987 hornsund, march/apr. 1985 hornsund. july/aug. 1987 kovalskifjellet, storfj., aug. 1989 isfjorden, july 1990 14 8 0 0 0 0 0 0 0 0 28 0 0 0 13 18 14 12 0 0 14 5 0 22 25 0 0 0 6 3 10 0 0 0 0 0 0 0 0 0 0 0 1 3 9 28 29 9 0 5 7 0 4 0 161 0 7 2 2 10 0 0 0 0 23 0 29 0 0 0 21 0 7 8 0 0 0 0 14 0 15 99 0 14 4 f. mehlurn & g . w . gabrielsen specimens. identification of prey was primarily based on fish otoliths, squid beaks, polychaete jaws, crustacean exoskeletons and intact speci mens. all otoliths were counted and (if intact) lengths measured to the nearest 0.1 mm using a micro scope with a measuring ocular. two otoliths dif fering less than 0.2 mm in length were considered to be from the same fish. the number of fish ingested was estimated as half the number of otoliths within each 0.2 mm length category. in the samples’ from hornsund in spring 1985, the number of fish ingested was based only on the total number of otoliths divided by two. the lengths of polar cod specimens were estimated according to frost & lowry (1981) where fish length (cm) = 2 . 1 9 8 ~ + 1.588 (x is otolith length in mm). the sizes of polar cod found in different bird species in spring and summer were compared to the classification of age classes given by l a m e & gulliksen (1989). they found that the mean fork length of one-year-old specimens was 81.6 mm (sd = 9.3) in the period 25 m a y 4 june, and 102.0mm (sd = 12.6) in the period 31 july 7 august. two-year-old polar cod had cor respondingly mean lengths of 108.7 mm (sd = 9.1) and 125.3 mm (sd = 21.6). l0nne & gul liksen found no older age-classes associated with sea ice. student t-test was used for determining differences in sizes of polar cod taken by different seabird species. a count was made of the crustaceans in each stomach or estimated from subsamples when present in large numbers. the length of whole crustaceans was measured to the nearest mm. when only fragments were encountered, the length of the posterior part was measured to the nearest 0.1 mm by means of microscope and measuring ocular (bradstreet 1980). estimates of total length based on the measurements of posterior parts were made in accordance with the equations given by bradstreet (1980). for the summer samples of little auks, wet weights of crustaceans were used. dry weights of amphipods were estimated from total lengths according to the equations given by bradstreet (1980). wet weights were then estimated from the dry weights. for the water content of parathemisto libellula we used the value 82.4% given by ikeda & skjoldal (1989), and for unidentified amphipods we used an estimated value of 80%. the different age groups of the euphausiid thysanoessa inerrnis were determined according to dalpadado (1989), who classified first year individuals at 13-18 mm and second year individuals at 20-25 mm. in the little auk samples from isfjorden in 1990, the total length (lt, in mm) of copepods was measured from the tip of the head to the end of the furca (accuracy 0.01 mm). conversion from length to dry weight (pg) of calanus was based on the relationships given by franz & die1 (1984): a water content of 73.5%, which was given for calanus finmarchicus adult females (ikeda & skjoldall989), was used for estimating wet weight from dry weight of c. finrnarchicus/glacialis. the number of polychaetes ingested was deter mined by counting the number of polychaete jaws present in the stomach sample. similarly, squid were identified by their beaks. when both upper and lower halves of beaks were present in the stomach sample, the number of squid ingested was determined by counting the lower beaks of squid present. in order to reduce the number of prey categories, the food items recorded were grouped into the following taxa: nereids (polychaeta, nereidae), gastropods, cephalopods, copepods, gammarids (gammaridea), hyperiids (hyperii dea), amphipoda indet., euphausiids, decapods, polar cod, other fishes, pisces indet., and others. remains of crustaceans which could not be identified to a lower taxonomic level than amphipoda were classified under “amphipoda indet.”. similarly polar cod is treated separately from other fishes because of its importance in seabird diets. “other fishes” includes all ident ifiable fishes except for polar cod. “pisces indet.” comprises fish remains not identified, which may also include polar cod remains. we mainly used the frequency of occurrence and the numerical abundance of different prey taxa in the analysis of the diet of the different seabird species (duffy & jackson 1986). fre quency of occurrence was determined for each bird species as the percentage of sampled birds in which the prey type occurred (empty stomachs were not included). numerical abundance was defined as the percentage in numbers of a prey type compared to the total number of identified prey items. percentage by weight was calculated by dividing the weight of a particular prey type by the total weight of all prey combined. the latter measure was applied for the little auk samples, only. dry weight = 10(1.167179+0.36w73lt). diet of high-arctic seabirds 5 in comparing similarity in diets we used mori sita’s index, “c”, of overlap (horn 1966; dia mond 1983) on our frequency of occurrence data. this index ranges from 0 (no overlap) t o 1 (com plete overlap). this index is usually applied t o numerical abundance data. we chose rather t o use frequency of occurrence because in many of our samples good values of numerical abundance of some taxa could not be obtained due t o decay of the food items in the stomachs of the birds. we believe that this use of the index is suitable for determining which species are most similar in diet. cluster analyses using the single linkage method (pielou 1984) were made, and tree dia grams were constructed, based upon indices of dissimilarity, “d” = 1 c. difjiculties in data interpretation in the analysis of seabird stomach samples, single measures of diet carry bias and have the potential to distort the true diets of the birds. for example, often only fragments of prey items are found, mainly the least digestible parts such as fish oto lithis, squid beaks, and polychaete jaws. thus, although the frequency of occurrence measure ment is easily obtainable, it will over-represent the most persistent prey species found in the stomach samples as well as prey which are only present in low numbers. if the sample contains considerable differences in prey sizes, the numeri cal abundance measure of diet tends to over estimate the importance of small prey. adequate measurement of a seabird’s diet would be the mass or the nutritional value of freshly ingested matter of the different prey taxa. however, such information is usually not available because of the different states of digestion of the prey items. for some prey species it is possible, on the basis of allometrical relationships, to estimate the total length or mass of specimens from the lengths of different body parts. these problems have been discussed in detail by duffy & jackson (1986). such diet measurement problems do not apply to seabird species which carry food to their young in their beaks or gular pouches. in our study, only little auks feeding their young give suitable data on prey composition by mass. this study is based on material collected over several years. in the results section we have combined data from the various years, and our interpretation of the diets of the different seabird species may be biased by inter-annual variation in food availability. we have combined the data because of low sample sizes in individual sampling periods. the samples collected in ice-covered areas were collected over a wider geographical area in the marginal sea ice zone in eastern parts of svalbard rather than at a fixed geographical locality. in addition, spring samples were obtained in areas farther south than the summer samples because of seasonal differences in ice cover. results diet composition of seabird species in coastal areas versus the marginal ice zone fulmar fulmarus glacialis. the diet of 50 birds included nereids, cephalopods, crustaceans and fish (fig. 2). nereids (nereis irrorata), cepha lopods (gonatus fabricii) and polar cod occurred most frequently in the pelagic samples, while cephalopods, decapods and fish other than polar cod dominated the coastal samples. the pelagic amphipod parathemisto libellula occurred only in samples from the marginal ice zone, 22.7% of those examined. nereids occurred in 45.5% of fulmar samples from the marginal ice zone, and none were found in samples from coastal areas. cephalopods occurred in 31.8% and 75.0% of the birds from ice-covered and coastal areas, respectively. kittiwake rissa tridactyla. polar cod was the dominant food taxon in the marginal ice zone (70.2% of the birds), but lower (28.8%) in coastal areas (table 2). in the total material, polar cod was found in 48.0% of the birds. the pelagic amphipod parathemisto, occurred in 30.3% of the bird specimens from coastal areas, but was not found in birds from the marginal ice zone. other taxa present in the coastal samples were cepha lopods, copepods and euphausiids. in the coastal spring samples (hornsund in marchiapril 1985), polar cod occurred in 44.0% of the birds along with other fish including lantern fish benthosema sp., atlantic cod gadus morhua, and snailfish liparidae (fig. 3). other prey of hornsund birds were squid ( gonatus fabricii) and polychaetes (nereis irrorata), with smaller num bers of amphipods and decapods. during chick-rearing, euphausiids and amphi pods were more frequent in the birds sampled in 6 f. mehlum & g . w . gabrielsen table 2. frequency of occurrence of prey taxa (% of birds investigated) in kittiwakes rksa fndactylu, briinnich’s guillemots uria lomuia, black guillemots cepphlls grylle, and little auks alle alle, in birds collected in the marginal ice zone (miz) versus coastal areas (c). chick diet of briinnich’s guillemots from kovalskifjellet is shown separately (k). sample sizes in brackets. kittiwake br. guillemot b1. guillemot little auk prey taxon nereids gastropods cephalopods copepods amphipoda indet. gammarids hyperiids euphausiids decapods polar cod other fishes pisces indet. other 12.3 16.7 1.1 11.5 0 0 53.8 0 1.8 1.5 0 3.8 0 0 17.3 0 0 6.1 0 11.5 0.5 0 0 0 0 3.0 4.5 0 0 4.8 3.8 66.7 1.8 4.6 22.5 15.4 0 0 21.1 8.3 0 1.5 4.5 38.5 0 9.5 30.8 16.7 0 30.3 64.0 3.8 0 0 3.8 30.6 0 15.2 7.9 38.5 0 0 3.8 0 7.0 6.1 14.6 7.7 0 0 32.7 0 70.2 28.8 28.1 34.6 83.9 71.4 9.6 5.6 22.8 18.2 1 . 1 19.2 11.5 14.3 15.4 0 24.6 30.3 14.6 19.2 4.0 28.6 21.2 13.9 1.8 1.5 0 0 0 0 5.8 19.5 fulmar nereids g a s t r o p o d s c e p h a l o p o d s c o p e p o d s gammarids boreo a d u s other ?ishes p i s c e s indel. other 0 20 4 0 60 80 7 100 % i i pelagic. summer (n22) fulmar nereids g a s t r o p o d s c e o h a l o o o d s ‘copepods gammarids olher 0 20 4 0 60 80 100% fig. 2. frequency of occurrence and numerical abundance (hatched) of prey taxa found in fulmars fulmarus glacialis. ~ 0 0.7 0 88.7 4.2 24.6 68.3 23.9 63.4 0 0 18.3 3.5 coastal areas than in spring (fig. 3). in the july/ august 1987 samples from the kongsfjorden area, the pelagic amphipod parathemisto libellula occurred most frequently (46.3%), while euphau siids (mainly thysanoessa inermis), polar cod and polychaetes (nereis sp.) were found in 24.4%, 19.5% and 19.5% of the samples, respectively. in the marginal ice zone (fig. 3), birds were sampled in the spring (april 1985 and may/june 1986) and summer (august 1982 and july/august 1984). fish dominated the diet during both periods with polar cod, the species most fre quently encountered during spring (frequency of occurrence 42.3%), supplemented by coalfish pollachius oirens, haddock melanogrammus aeglefinus, lantern fish benthosema sp., capelin mallotus villosus, snailfish (liparis sp., care proctus sp.), and blennies (lumpenidae, zoar cidae). the polychaete nereis sp. was found in 23.1% of the birds. in july/august 1984 polar cod was found in 93.5% of the birds; other fish species occurred in 22.6% of the birds. ivory gull pagophila eburnea. a total of 19 specimens of ivory gull were collected during three different periods (fig. 4), all in pelagic areas within the marginal ice zone. fish was the dominant prey found, and polar cod occurred in 52.6% of the birds examined. other fish species diet of high-arctic seabirds 7 kittiwake coastal. spring (n25) kittiwake coastal. summer (n41) nereids gastropods cephalopods copepods gammarids boreo adus other fishes pisces indet. all nereids gastropods cephalopods copepods gammarids hyperiids boreo adus other fishes pisces indet. other other 0 20 40 60 80 100 % 0 20 40 60 80 100 % nereids gastropods cephalopods copepods gammarids hyperiids boreo adus other fishes pisces indet. other e=i=l= 0 20 40 j 60 80 100 % pelaglc. summer (n= 31) nereids gastropods cephalopods copepods gammands hyperiids boreo adus othergshes pisces indet. other 0 20 40 60 80 100 % fig. 3. frequency of occurrence and numerical abundance (hatched) of prey taxa found in kittiwakes r b a tridactyla. (blenny lycodes sp., atlantic cod, and coalfish) occurred in 26.3% of the stomach samples, while mammal fat (probably seal) was found in 21.1% of birds. six gammarus wilkitzkii, a sympagic amphipod, were found in one bird. echinoderms occurred in two birds, but was suspected of being obtained by scavenging from seal excrement. ivory gull nereids gastropods cephalopods copepods gammarids h periids amphi od% indet. gphausiids decapods boreo adus olhereishes pisces indet. other 0 20 40 60 80 100 % fig. 4. frequency of occurrence and numerical abundance (hatched) of prey taxa found in ivory gulls pagophila eburnea. briinnich's guillemot uria lomvia. the pelagic amphipod parathemisto occurred in the highest frequency (64.0%) among samples from the mar ginal ice zone, while gammarid amphipods and euphasiids had the highest occurrence (38.5%) in coastal samples (table 2). gammarid amphipods and euphausiids were encountered in lower occur rence in the marginal ice zone (4.5% and 7.9%). polar cod was found in 28.1% and 34.6% of the birds in ice-covered and coastal areas, respect ively. amphipods and euphausiids were encountered most frequently in the early spring samples from hornsund (april/may 1985), occurring in 71.4% and 64.3% of the 14 birds, respectively. however, euphausiids (mainly thysanoessa inermis) dom inated in numbers and accounted for 68.5% of all identifiable prey items (fig. 5). the pelagic amphipod parathemisto was not encountered, and the dominant amphipods in the samples were gammarellus homari and anonyx nugax, both benthic living species. polar cod was also a com mon prey, occurring in 42.9% of the birds. in the 12 summer samples from coastal areas from 8 f. mehlum & g . w . gabrielsen i brunnich’s guillemoc i coastal. spring ( n 14) nereids gastropods cephalopods copepods gammarids hyperiids boreo adus other ?ishas pisces indei. other 0 20 40 60 80 100 briinnichs guillemot nereids gastropods cephalopods copepods gammarids hypenids amphi oda indet. gohausiids n % nereids gastropods cedhalooods conebods1 i pisces indet. other -_ j l brunnich’s guillemot pelagic, spring (n= 76) nereids gastrodods 0 20 40 60 80 100% pelagic. summer (n= 13) cephalopods copepods gammarids boreogadus other fishes pisces indet. other 0 20 40 60 80 100 % fig. 5. frequency of occurrence and numerical abundance (hatched) of prey taxa found in brunnich’s guillemots uria lomuia. kongsfjorden (june/july 1984-85), benthic amphipods occurred most frequently (33.3%), while polar cod and other fish species (mainly blennies and capelin) occurred in 25.0% of the birds. the samples from the marginal ice zone during the spring period (fig, 5) comprise a total of 76 birds from feb./march 1987, april 1985 and late may/early june 1986. the most frequently occur ring taxon was the amphipod parathemisto, occur ring in 63.2% of the samples, while polar cod occurred in 27.6% of the birds. the euphausiid thysanoessa inermis and the amphipod para themisto libellula accounted for 51.3% and 36.6% of the 1486 identifiable prey items. in all but one bird the euphausiids were confined to the samples from feb./march 1987. decapods were encoun teredin 15.8% of the birds. in the april/may 1985 sample, however, the decapod pandalus borealis was the most frequent prey: 45.6% of the stomachs. the samples collected in ice-covered waters during the summer seasons (fig. 5) comprise 13 birds, of which 7 were first-year birds still accompanied by one of their parents. para themisto was the dominant prey in the sample occumng in 69.2% of the birds and accounting for 200 of the 213 identified items (93.9%). polar cod was the second most important and occurred in 30.8% of the birds. only one prey specimen of gammarid amphipods was found, the sympagic species gammarus wilkitzkii. no difference was found between the diet of adult and first-year birds. parathemisto occurred in four out of seven first-year birds (57%). briinnich’s guillemot chick diet was studied at kovalskifjellet in 1989 (table 2). in the 161 food deliveries observed the chicks were almost exclu sively fed fish, of which 83.9% were polar cod, 9.9% snakeblennies (lumpenidae), 1.5% scul pins (cottidae), and 4.3% unidentified fishes; one chick meal delivered was a squid. black guillemot cepphus grylle. the diet of diet of high-arctic seabirds 9 and 9.5% of the birds, respectively. polychaetes, gastropods, parathemisto, euphausiids, mysiids and decapods were only encountered in the coastal samples. black guillemots was generally more diverse in coastal areas than in the marginal ice zone (table 2). benthic dwelling prey were frequent in the coastal samples, whereas polar cod was dominant in pelagic, ice-covered areas. in inshore waters at hornsund (march-april 1985) and kongsfjorden (july-aug. 1985), the diversity of prey was high with a high proportion of benthic invertebrates in addition t o polar cod and benthic sculpins (fig. 6). the polychaete nereis irrorata had the highest frequency of occur rence (53.8%), followed by benthic amphipods (48.3%) and decapods (32.7%). in hornsund birds polychaetes were dominant: frequency of occurrence = 96.6%, and numbers = 87.3%. amphipods were also numerous, mainly gam marellus homari, a species usually found in shal low water in the hornsund region (opalinski & weslawski 1989). in offshore, ice-covered areas (fig. 6), polar cod was the dominant prey, occurring in 71.4% of the birds, with other fishes (coalfish and lycodes) and sympagic amphipods occurring in only 14.3% little auk alle alle. little auk foods were mainly small invertebrates, with copepods dom inant by occurrence and numbers. the diet in coastal waters was more diverse than in the mar ginal ice zone (table 2) comprising gastropods, copepods, amphipods, euphausiids, decapods, chaetognaths and fish larvae. gastropods, euphausiids and decapods were not present in the pelagic samples. the only coastal area spring sample is from hornsund in march/april 1985. copepods were found in 66.7% of the birds. however, amphipods other than parathemisto and euphausiids were also frequent in the diet, and the latter accounted for 92.4% of the number of prey items recorded except for copepods. copepods were present in 91.3% of all coastal samples in summer and they accounted for 85.3% in the wet weight of the prey (fig. 7). the pelagic black guillemot coastal. spring (n29) black guillemo! coastal, summer (n= 23) nereids gastropods cephalopods copepods gammands hyperiids 0 20 4 0 60 80 100 n nereids gastropods cephalopods copepods gammarids nereids gastropods cephalopods copepods gammands h periids amohidoc& indet. % 0 20 40 60 80 1 0 0 % i black guillemo: pelagic, spring (n= 12) nereids fl black guillemot pelagic, summer (n= 9) hyperiids boreo adus otherqishes pisces indet. other 0 20 40 60 80 100 ai % gastropods cephalopods copepods gammarids hyperiids boreo adus other %shes pisces indet. other 0 20 4 0 60 d 80 100 % fig. 6. frequency of occurrence and numerical abundance (hatched) of prey taxa found in black guillemots cepphus grylle. 10 f. mehlum & g . w . gabrielsen a nereids gastropods nereids 1 gastropods i cephalopods copepods gammarids i hyperiids boreo adus other?ishes [-j boreo adus pisces indet. othertshes 0 20 40 60 80 100% other other / i j pisces indet. 0 20 40 60 80 100 % nereids gastropods cephalopods copepods gammarids hyperiids boreo adus otherfshes pisces indet. other little auk p c + j 0 20 40 60 80 100% nereids 1) gastropods cephalopods copepods gammarids hvderiids amphi oda indet. adhausiids i r // becapods bore0 adus other bishes pisces indet. other 0 20 40 60 80 100 % fig. 7. frequency of occurrence and numerical abundance (hatched) of prey taxa found in little auks alle alle. for the coastal summer samples wet weight i s presented instead of numerical abundance. amphipods parathemisto spp. and decapod larvae were the second and third most frequent prey items encountered, and were found in 75.6% and 70.9% of the birds, respectively. copepods were found in all birds collected during summer in hornsund (1987) and isfjorden (1990), while they occurred only in 21.4% of the birds in kongsfjor den (1985). in the kongsfjorden sample para themisto was the dominant prey, occurring in 57.1% of the birds, and followed by gammarids with 28.6%. the july-aug. hornsund birds con tained 86.1% wet weight copepods, while larval stages of decapods (mainly eupagurus) comprised the second most important prey taxon with 70.1% of the macroplankton wet weight (with copepods excluded). parathemisto spp. constituted 25.3% of the macroplankton wet weight and were the most important taxon relative to frequency in numbers; they accounted for 52.5% of the macro planktonic prey items. two species of para-them isto were encountered. p. abyssorum occurred more frequently than p. libellula (40.0% and 12.1% of macroplanktonic prey items, respect ively) and contributed more to the total weight of macroplankton consumed by the birds (15.4% vs. 9.9%). euphausiids were of minor importance in the hornsund sample and accounted for only 1.0% of the macroplankton weight. copepods accounted for 70.9% of the total wet weight of the prey in the isfjorden sample, while parathemisto spp. were second (18.5%), followed by thy sanoessa sp. (6.4%) and decapod larvae (3.9%). parathemisto abyssorurn was the dominant para themisto species (198 of 206 individuals, or 96%). the summer 1990 material from isfjorden was analysed in order to describe the composition of different calanus stages and species, and to determine their weights. of 4903 whole specimens of copepods, c. jinmarchicuslglacialisis dominated with 96.0% copepodite stage v (mean dry weight per individual copepod 408 pg), 1.9% females stage vi (mean dry weight 539pg), and 1.8% copepodite iv (mean dry weight 187pg). only five specimens of c . hyperboreus were found, three of copepodite iv (mean dry weight 685 pg) and two copepodite v (mean dry weight 2267 pg). diet of high-arctic seabirds 11 “ 1 3 2 l 2 6 m x x x x x x x x x xxx x x x x x x x the estimated dry weights of c . finmarchicus/ glacialis from the pelagic samples of summer 1982 averaged 608 pg (range: 192-928 pg, n = 20). in the spring samples from the marginal ice zone, copepods and chaetognaths were most fre quently encountered and occurred in 60.0% and 46.7% of the birds, respectively (fig. 7, chaeto gnaths are listed as “others”). the pelagic amphi pod parathemisto libellula, sympagic amphipods, and one-year old individuals of polar cod were found in much lower percentages of the birds. late summer samples from pelagic, ice-covered areas (fig. 7) contained only copepods, par athemisto libellula and sympagic, gammarid amphipods (mainly apherusa glacialis and gam marus wilkitzkii). estimates of dry weights of the different prey taxa showed that gammarid amphipods, which were found in 28.6% of the birds, accounted for as much as 78.9% of the total weight of the prey. v 1 4 ” comparison of diet between seabird species and habitats a matrix of the frequency of occurrence of dif ferent prey taxa in the six seabird species inves tigated are shown in table 3 where they are separated by habitat: ice-covered versus coastal areas. polar cold was important for all seabird species (except the little auk) in the pelagic, partly ice-covered areas, but less important in the coastal samples where all bird species had a more varied diet. a second important prey taxon in the marginal ice zone was hyperiid amphipods. parathemisto libellula was the most common hyperiid in briinnich’s guillemots, and also frequent in ful mars and little auks in the marginal ice zone, and in kittiwakes from coastal areas. on the other hand, p. abyssorum was dominant in little auks from coastal areas. nereids were frequent in ful mars and kittiwakes in offshore areas, and in kittiwakes, briinnich’s guillemots and black guillemots in coastal waters. cephalopods occurred in three seabird species, but the fre quency of occurrence was > l o % in only two species. they were encountered in very high fre quency in fulmars in coastal areas, and less fre quent in briinnich’s guillemots and kittiwakes. in the marginal ice zone they were found only in fulmars, but at a lower level than along the coast. certain prey taxa had a frequency of occurrence of larger than 10% in only a single seabird species: copepods and chaetognaths in little auks, gastro pods in coastal black guillemots, and mammal fat in ivory gulls. table 3. summary table of the frequency of occurrence of different prey taxa in seabirds sampled in the marginal ice zone and :oastal areas. frequency of occurrence in bird stomachs x = 1040% xx = 40-70% xxx > 70% marginal ice zone fulmar kittiwake ivory gull briinnich’s guillemot black guillemot little auk _____ coastal areas fulmar kittiwake briinnich’s guillemot black guillemot little auk 12 f. mehlum & g . w . gabrielsen table 4. morisita’s indices for dietary overlap between seabirds sampled in the marginal ice zone and coastal areas in the svalbard region. the indices are based on frequencies of occurrence. marginal ice zone species fugla ritri paebu urlom cegry fuhnar 0 kittiwake 0.62 0 ivory gull 0.46 0.90 0 briinnich’s guillemot 0.54 0.41 0.37 0 black guillemot 0.53 0.97 0.88 0.41 0 little auk 0.22 0.12 0.11 0.47 0.20 coastal areas species fugla ritri urlom cegry fuhnar 0 kittiwake 0.38 0 briinnich’s guillemot 0.38 0.68 0 black guillemot 0.28 0.53 0.61 0 little auk 0.17 0.34 0.26 0.33 ~ (fugla = fulmar, ritri = kittiwake, paebu = ivory gull, urlom = briinnich’s guillemot, cegry = black guillemot, alall = little auk). the morisita’s indices of dietary overlap between the six seabird species studied in the marginal ice zone and five species in coastal regions are shown in table 4. these matrices are calculated from the frequencies of occurrence of each of the 14 prey categories listed in table 3. the corresponding dendrograms of dissimilarity (fig. 8) show that in the marginal ice zone there is a high similarity in diet between black guille mots and kittiwakes, both of which exploit ice associated prey. ivory gulls also showed a diet similar to these two species, while the most distant species in diet similarity was the little auk, which mainly fed upon copepods. the dendrograms indicate a lower similarity in diet between the species in coastal areas than in offshore areas. in coastal birds the highest similarity in diet was between briinnich’s guillemots and kittiwakes; both fulmars and little auks had very low dietary overlap indices in coastal regions. the highest dietary overlap between marginal ice zone and coastal habitats by applying morista’s index was for little auks (0.72), followed by kit tiwakes (0.70), and fulmars (0.57). the lowest overlap value was for the black guillemot (0.29), probably reflecting its benthic versus under-ice foraging habits. the value for briinnich’s guille mot was intermediate (0.43). sizes of polar cod, parathemisto spp. and thysanoessa inermis consumed by seabirds a comparison of prey sizes for different seabird species and seasons allows the predominant prey cohorts and differences between predator species to be determined. length distributions of polar cod based on otolith lengths (fig. 9) and l ~ n n e & gulliksen’s (1989) classification indicate that in spring briinnich’s guillemots and little auks feed mainly on one-year-old cod. the mean lengths of polar cod in the briinnich’s guillemots collected during spring varied from 75 to 96 mm between samples, whereas those from the single sample set of little auks averaged 81 mm. the polar cod taken by kittiwakes and black guillemots com prised individuals of both one-year-old and older. mean lengths in spring varied from 78 to 115 mm for black guillemots, and from 83 to 131mm between samples in kittiwakes. in hornsund (april/may 1985) kittiwakes caught polar cod significantly larger than both briinnich’s and black diet of high-arctic seabirds 13 0.6 coastal areas (single linkage method! ’ 0.5 o.6 t 0.2 0.1 0.0 t 5 m marainal ice-zone fig. 8. cluster diagram of dissimilarity in diet between five scabird species in coastal areas and six species in the marginal ice zone. the dissimilarity is measured a s one minus morisita’s index, using the frequency of occurrence data. guillemots (t = 11.3, p < 0.001; and t = 6.1, p < 0.001, respectively). in summer, mean lengths of polar cod in kitti wakes varied from 106 to 134mm (three data sets), compared to from 97 to 136mm in black guillemots (two data sets). the majority of the polar cod eaten by kittiwakes and black guillemots in summer 1984 were probably one-year-old fishes (mean lengths: 97 mm and 106 mm, respectively). in the other samples, however, the proportion of older polar cod was higher (mean lengths: 118 to 136 mm). length distributions of parathemisto libellula in samples from different seabird species and seasons are shown in fig. 10. in spring and sum mer briinnich’s guillemots preyed upon relatively large amphipods, with mean lengths from 25.0 to 31.5mm. kittiwakes, little auks and fulmars seemed to have taken smaller-sized amphipods during the summer, though the small sample sizes for kittiwakes and fulmars makes things uncer tain. in the little auk samples collected from isfjorden in july 1990, the mean length of p. libellula was 11.5 mm, while the mean length of the much more frequent prey p. abyssorum was 6.1 mm. the only two measured p. libellula in kittiwakes from the spring samples were, like most specimens found in the briinnich’s guille mot, from the larger cohort. the majority of the thysanoessa inermk taken by briinnich’s guillemots and little auks in spring and kittiwakes in summer were two-year-old indi viduals based on dalpadado’s (1989) classification of age groups of this euphausiid (fig. 10). in the coastal summer sample of little auks from isfjorden 1990, the mean lengths was 6.1mm (range: 5.0-15.0 mm), which indicates that these birds preyed upon the 1990 year’s production of thysanoessa inermis. discussion in this study, which is based on 719 food samples from six seabird species in the svalbard region, we have demonstrated the diversity of prey taken by seabirds in the region and also documented the dominance of certain key prey species, such as polar cod and parathemisto, which are con sumed by most seabirds. we found the diet of the smallest species studied, the little auk, least similar to the diet of the other species. it fed mainly on copepods. .’ fishes the polar cod is a principal prey species for sea birds in pelagic, ice-covered waters in the eastern svalbard region (table 3), as has been described for seabirds in the canadian high arctic (brad street & cross 1982). the year classes i and i1 of this species associate with ice and may be found in crevices in the ice or between sandwiched ice flows (l@nne & gulliksen 1989). older polar cod are confined to the open water masses. thus, the year classes of young polar cod may be treated as part of the sympagic fauna. the distribution of young polar cod in the ice-covered areas around svalbard is not known in detail. however, a spawning area of the western component of the barents sea population of polar cod has been k it ti w nk e l en gt hs o f p ol ar c od 50 10 0 i5 0 20 0 (m m ) 1 : : : : : : : : : : : : : : 1 (2 9) m ar ch la pr . 19 85 (1 1) a pr ./m ay i 98 5 (1 1 ) -=t= m ay /j un e 19 86 (4 ) t ju ly 1 98 2/ 83 (2 6) a ug . 19 82 (2 9) july/aug. 19 84 (1 1 ) & a ug . 19 87 b ri in ni ch 's c ui ll em ot 50 1 0 0 i5 0 20 0 (m m ) t : : : : : : : : : : : : : : 1 fe br ./m ar ch 1 98 7 m ar cw a pr . i9 85 a pr .lm ay 1 98 5 m ay /j un e 19 86 (1 56 ) = (1 43 ) (1 7) f r (2 2) (2 ) - ju ly 1 98 5 b la ck g ui ll em ot 5 0 10 0 15 0 20 0 (m m ) m ar cm a pr . 19 85 a pr ./m ay 1 98 5 m ay /j un e 19 86 ju iy /a ug . 19 82 (1 3) (6 ) (1 1 ) (7 ) (2 4) a uy . 19 84 l it tl e a uk 50 10 0 15 0 20 0 (m m ) i : : : : : : : : : : : : : : { m ay /j un e 19 86 (5 ) fi g. 9. e st im at ed l en gt hs ( m ea n & st an da rd d ev ia tio n, a nd ra ng e) o f po la r co d b or eo ga du s sa id 0 in d if fe re nt s ea bi rd sp ec ie s. t he e st im at es a re b as ed u po n ot ol ith l en gt hs ( l m ne & g ul lik se n 19 89 ). sa m pl e si ze s ar e gi ve n in b ra ck et s. p nr rt he m is tn li he llu ln 5 15 2 5 35 ( m m ) i : : : : : : : : : : : : : : : : { + fe br /m ar ch 1 98 7 m ay /j un e i9 86 a . a ug . 19 84 3 s a ug 19 82 s 4+ ju ly 1 99 0 a u g . 19 82 t h ys n n oe ss n in er m is 5 is 25 3 5 (m m ) 1 : : : : : : : : : : : : : : : : 1 (9 ) ju ly 1 98 2 fi g. 1 0. e st im at ed l en gt hs ( m ea n 2 s ta nd ar d de vi at io n, a nd ra ng e) of t he a m ph ip od p ar ar he m is ro li be llu h an d th e eu ph au si id t hy su no es sa in er m is i n di ff er en t se ab ir d sp ec ie s. s am pl e si ze s a re g iv en in b ra ck et s. m ar ch /a pr . 1 98 5 m ar ch la pr . i9 85 ju ly 1 99 0 diet of high-arctic seabirds 15 p. libellula, presumably the young of the year, becomes available t o seabirds. p. libellula is not regarded as part of the sympagic fauna, but it may be found in the water column just below sea ice (l0nne & gulliksen 1991a). wing (1976) studied the ecology of p. libellula and p . pacijica in south eastern alaskan waters and found that both species migrate vertically between day and night most of the year. he suggested that p. libellula made an upward movement of 15&200m each night with a significant part of the population between the surface and 50m. similarly, gul liksen (1984) reported that the biomass of this amphipod under land-fast ice in eastern svalbard varied between day and night, with the highest biomass around midnight. this vertical migration may influence the availability of the amphipod as prey for seabirds, making them available in highest numbers for surface or near-surface feeders at night. the smaller hyperiid p. abyssorurn was found only in little auks taken along the western coast of spitsbergen (hornsund and isfjorden). this amphipod was dominant in both areas during summer, though the specimens taken were much smaller than p. libellula. zelichman & golovkin (1972) also found a high frequency of p . abys sorurn in the diet of little auks at novaja zemlja. the p. libellula found in the summer samples of little auks were of the small cohort, probably the young of the year, similar in size to those found in little auks in arctic canada (bradstreet 1982). weslawski & kwasniewski (1983) suggested that p. abyssorurn was an indicator of atlantic water in the svalbard area, because in their study, the species was found only in atlantic water in the western parts and not in the arctic water in the eastern parts of the archipelago. however, the species is also widespread in the arctic ocean as well as in deep water in the sub-arctic (ekman 1953). in lancaster sound, northwest terri tories, p. abyssorurn occurred in deeper water than p . libellula and were not thought to be important as prey for other seabirds with the possible exception of the deep-feeding briinnich’s guillemot (bradstreet 1976). krill, mainly thysanoessa inerrnis, were also important prey species in briinnich’s guillemot , but only in the spring. this is probably because these arcto-boreal euphausiids are primarily found in atlantic water masses, which around svalbard are normally not ice-covered during summer (dalpadado & skjoldall991). birds were located east of svalbard, in the region north of hopen and east of edge0ya (loeng 1989). it is likely that the young polar cod from this locality will spread into large areas. capelin was not encountered frequently in the diet of any of the seabird samples, but was found in kittiwakes and briinnich’s guillemots in low numbers. this pelagic fish is an important prey species for seabirds breeding at bj0rnaya (v. bakken, pers. comm.) and hopen (76”30’n) (r. barrett, pers. comm.). the barents sea capelin spawns along the coasts of north norway and the kola peninsula, while the young capelin mature in the central or northern barents sea. capelin is known to follow the retreating ice-edge north ward during the summer, preying upon the grow ing populations of copepods (loeng 1989). capelin is normally not abundant in svalbard waters except for the southeastern parts after the summer disappearance of sea ice. however, capelin may occasionally be found locally along the western coasts of spitsbergen. the seabirds sampled for this study were collected outside regions where capelin is normally abundant at that time of year. another factor that might con tribute to the lack of capelin in the diet of the seabirds sampled is that the capelin stock in the barents sea was dramatically depleted in the 1980s and the population crashed in 1985-86 (hamre 1988). pelagic crustaceans our results indicate that parathemisto libellula is also a key prey species for several species of seabirds in the svalbard and northern barents sea areas, a finding similar to that for the canadian arctic (bradstreet & cross 1982). this amphipod also comprises a significant proportion of the diets of ringed seals pusa hkpida (gjertz & lydersen 1986) and harp seals phoca groen landica in svalbard and the northern barents sea (lydersen et al. 1991). according t o our data, large sized cohorts, probably adults of p . libellula, form a staple food of briinnich’s guillemots in the marginal ice zone during spring. this prey must be very abundant in the marginal ice zone east of svalbard. large groups of briinnich’s guillemots, numbering thousands of birds, have been observed foraging in open leads in this area (per sonal obs.). of the birds collected from these leads for dietary analysis, most were gorged with p. libellula. during summer a smaller cohort of 16 f. mehlum & g . w . gabrielsen sampled only north of the frontal area between atlantic and arctic water masses during the sum mer. calanoid copepods were important as prey only for the little auk, although they also occurred infrequently in kittiwakes, briinnich’s and black guillemots. three cafanus species are common in svalbard waters: c . finmarchicus, confined to atlantic water masses, and c . glacialis and the larger c . hyperboreus in arctic water masses. one might expect the larger c. hyperboreus to be selected by little auks if equally accessible and abundant, because of the higher energy content per prey individual taken by the bird. in north western baffin bay, little auks selected the largest species of copepods (c. hyperboreus) and the largest life stage of both c . hyperboreus and c . glacialis (bradstreet 1982). however, in eastern lancaster sound, copepods were absent and the diet was dominated by amphipods (bradstreet 1976). in our july samples from isfjorden, c. glacialis (copepodite stage v ) totally dominated in numbers, and only five specimens of c. hyper boreus were found. however, nothing is known about the composition of plankton available t o little auks at the time of collection. similarly, in ice-filled waters east of svalbard in august 1982, the size distribution suggests that the c . finmarchicus/glacialis taken belonged t o the larg est stages (copepodite v and adults). decapod larvae were also frequent as prey for little auks in the coastal samples. the pre dominating species encountered was eupagurus pubescens, which is abundant as zoea larvae in coastal spitsbergen from april t o september (weslawski 1987). polychaetes, squid and other soft-bodies prey nereids (the only species identified was nereis irrorata) were found in seabirds sampled both in coastal and ice-filled areas. only the chitinous jaws were present, which have low digestibility and thus may remain in the digestive tract for long time. in the coastal samples, nereids are probably taken by black guillemots while feeding on benthic dwelling prey. nereids were also re corded as prey for surface feeding seabirds such as kittiwakes and fulmars. these polychaetes are known to “swarm” in surface waters during repro duction and may thus be available t o surface feeding seabirds (pettibone 1954). the only remains of cephalopods found in the birds were their beaks. all beaks identified were from the squid gonafus fabricii, a widely dis tributed species. cephalopods were the dominant prey in coastal samples of fulmars, but only occurred at low levels in pelagic samples. squid were also found in kittiwakes and briinnich’s guillemots, but only in coastal samples and in low numbers. the distribution and ecology of g . fabricii in svalbard is unknown, and its apparent difference in abundance in our samples from sea birds from coastal areas and the marginal ice zone cannot be explained. however, the presence of beaks in the stomach of fulmars agree with pre vious studies in arctic regions (duffy & sergant 1950; belopolskii 1957; de korte 1972; bradstreet 1976; lydersen et al. 1989). g. fabricii is found throughout the water column, with mainly small individuals occurring near the surface (nesis 1965). the mean length of g . fabricii eaten by fulmars in lancaster sound was 143 mm (60 g), which corresponds t o an estimated age of 12 months (bradstreet 1976). no soft parts of nereids and squid were found in the samples. thus, the importance of these taxa as prey for seabirds might be less than indicated by the frequency of occurrence and numerical abundance measures. other soft-bodied prey that disappear rapidly from the digestive tract of the seabirds would be difficult to identify if not exam ined immediately after ingestion. we did not encounter organisms such as pteropods, cteno phores and scyphozoan jellyfish in our samples, but we suspect that they are taken by seabirds in the svalbard region equally as much as by seabirds in other regions (harrison 1984). we have observed fulmars feeding on jellyfish in western spitsbergen coastal waters (f. mehlum, pers. obs.). the importance of ice-associated prey the marginal ice zone in the waters around sval bard comprises important habitats for several sea bird species (mehlum 1989). certain species, such as the ivory gull, ross’ gull rhodostethia rosea and black guillemot, are mainly associated with the sea ice in pelagic areas, while others, such as the little auk, briinnich’s guillemot, kittiwake, and fulmar, are distributed both in the marginal ice zone and in ice-free regions (mehlum 1989). during the summer season a large proportion of diet of high-arctic seabirds 17 the birds feeding in these areas are presumably non-breeding individuals (mehlum 1989). in the marginal ice zone seabirds forage deep in the water column as well as on sympagic organ isms associated with sea ice. the sympagic fauna available as prey for seabirds have been classified into two types (melnikov & kulikov 1980): (1) autochthonous ice-fauna associated with multi year ice and including gammarid amphipods such as gammarus wilkitzkii, apherusa glacialis and onisimus sp.; and (2) allochthonous ice-fauna, found only temporarily in the ice, which in the barents sea includes polar cod and is associated both with first-year ice and multi-year ice. in svalbard, sympagic amphipods were not the main food source for any of the six seabird species studied. these amphipods were most frequent in the little auk and the black guillemot, but they occurred only in 16.7 and 9.5% of the birds exam ined, respectively. in little auks, the percentage by weight of the different prey taxa in the summer samples showed that the sympagic amphipods a. glacialis and g . wilkitzkii accounted for as much as 78.9% of the total weight. however, this high abundance by weight was biased by the fact that all the 297 specimens were found in 6 of 21 birds (all 6 from the summer 1982 sample). it therefore seems that sympagic amphipods (the autoch thonous ice-fauna) contribute little to the diet of seabirds foraging in ice-covered waters in the eastern svalbard region. according to l m n e and gulliksen (1991a), the abundance of the sympagic fauna depends on the age and the structure of the subsurface of the ice. they found high densities of sympagic amphipods under multi-year ice, while there were few or none under first-year ice. the proportion of multi year ice in the barents sea varies from year to year but is generally small in comparison with the waters north of svalbard and in the fram strait in the northern part of the greenland sea. based on vinje’s (1985) estimates, the maximum out flow of multi-year ice from the polar basin to the barents sea is 30,000 km2, or about 15% of the marginal ice zone at its maximum extent. the relatively low proportion of multi-year ice in the barents sea compared to the waters north of svalbard suggests a higher abundance of sym pagic organisms north of svalbard than in our sampling areas in the northern barents sea. this agrees with the results of lenne & gulliksen (1991a, b). in multi-year ice north of svalbard, l ~ n n e & gabrielsen (1992) found that sympagic amphipods were more important as prey for little auks and briinnich’s guillemots than in first-year ice in the northern barents sea. in the coastal areas and fjords in western spits bergen there is usually no sea ice during the summer months, and thus the sympagic fauna is not a potential food source for seabirds foraging in these areas. even though the sympagic fauna of amphipods may not be very important as prey for most sea birds in ice-covered waters near svalbard, they may be indirectly important as part of the prey of polar cod, at least in multi-year ice ( l m n e & gulliksen 1989). however, the diet of polar cod was dominated by calanoid copepods and para themisro in their study. bradstreet & cross (1982) reported similarly that the diet of polar cod caught at the landfast ice-edge at offshore locations in arctic canada was dominated by copepods and parathemisto, with only a small proportion of sympagic organisms present. the occurrence of sympagic amphipods in the diet of little auks during late summer agrees with bradstreet (1982) for northwestern baffin bay. bradstreet (1982) also described a seasonal shift in prey taken by little auks, where calanoid cope pods dominated the may samples and para themisto, apherusa glacialis and polar cod dominated in the august samples. it is apparent from our data and from lydersen et al. (1989) that a similar seasonal shift in diet occurs in the svalbard region from summer to autumn. cope pods, which dominated the diet in our spring and summer samples, were absent in little auks collected by lydersen et al. (1989) in september october in the hornsund region of svalbard; parathemisto and polar cod and striped snailfish liparis liparis dominated instead. the seasonal change in diet may be due to differences in avail ability of prey. diet similarities among species when comparing the diets of the different seabird species, we found the greatest similarity in the diets of black guillemots and kittiwakes foraging in ice-filled waters. both feed on ice-associated prey, primarily polar cod. in contrast, their prey are quite different in coastal areas, where the black guillemot takes mainly suprabenthic prey. at hornsund, lydersen e t al. (1989) found the highest similarity in the autumn diets of the little auk and briinnich’s guillemot, both ‘which feed 18 f. mehlum & g . w, gabrielsen mainly on polar cod and parathemisto. the three pursuit-diving species studied (i. e. the three acids) differ considerably in size and feeding ecology. the briinnich’s guillemot feeds on medium and large sized pelagic prey, whereas the little auk takes small pelagic prey, and the black guillemot suprabentic prey (mainly fish and crustaceans) in inshore regions and ice-associated prey in the marginal ice zone. in all the three surface feeding seabird species, fish, especially polar cod, are an important part of the diet. in the ice-covered areas these seabird species probably take advan tage of the high abundance of polar cod associated with sea ice. kittiwakes in hornsund (spring 1985) consumed significantly larger polar cod than both briinnich’s and black guillemots sampled during the same period. we have no good explanation for this difference, but the kittiwakes might have foraged in separate areas with a higher proportion of cod aged two-year-old or more. foraging areas of birds collected in coastal regions during the breeding season, seabirds are con strained in their foraging range by distance to the breeding site. during the chick-rearing period, the young have to be fed at certain rates in order to maintain normal growth before fledging. we have no detailed information of the feeding locations used most frequently by seabirds in sval bard and their relationship to where we collected birds in coastal areas. in southeast svalbard, we have recorded briinnich’s guillemots flying north ward with fish in their beaks as far as 95km southeast of the nearest breeding colony (f. mehlum unpubl.). we have also observed large numbers of seabirds feeding in coastal areas in kongsfjorden and hornsund, indicating that at least some prey are taken close to the colonies. the black guillemot, unlike other seabirds studied, feeds only in coastal areas close to the breeding site, usually less than 1 km distant (cairns 1987). in contrast to other atlantic alcids, their foraging range is constrained by the high workload needed to feed their two-chick clutches which they rear all the way to fledging (mehlum et al. 1993). some arctic seabird species are attracted t o special features along the coast where food is abundant. these include glacier faces and river outlets where prey organisms, especially crus taceans, are concentrated and easily obtainable. the existence of such feeding areas in front of glaciers in svalbard was observed at nor denskioldbreen in billefjorden and mittag-lef flerbreen in wijdefjorden by hartley & fisher (1936). in their study, the two dominant seabird species foraging in the fjords along the glacier fronts were fulmar and kittiwake, which mainly preyed upon the euphausiid thysanoessa inermis. similar observations have been made elsewhere in svalbard. norderhaug et al. (1977) described the phenomenon at smeerenburgbreen and mon acobreen in northwest spitsbergen, while mehlum (1984) reported concentrations of sea birds along the front of the large glacier austfonna on nordaustlandet, as well as along kongsvegen and the outlets of several small rivers in kongsfjorden. the literature also contains similar reports from greenland (hartley & dun bar 1938) and the canadian arctic (mclaren & renaud 1982; renaud & mclaren 1982). the exact nature of the mechanism responsible for the concentration of prey organisms in such areas is not known. mehlum (1984) suggests that the aggregation of organisms is caused by passive upwelling in connection with fresh water outlets beneath the glacier or at river outlets. the outflow of fresh water generates a reaction current of salt water (below the fresh water) towards the glacier face or river outlet, and the organisms are trans ported upwards to the freshwater layer. when they experience lower salinity, they may be more or less immobilized and thus easy prey for the birds. in 1983, mehlum (1984) observed large numbers of kittiwakes at river outlets in kongsfjorden feeding upon the amphipod par athemisto libellula. numbers of amphipods were found dead, apparently dying by the low salinity. aarset & aunaas (1987) have shown that this species is relatively intolerant t o low salinity water. the flow of fresh water from arctic glaciers and rivers varies through the summer and is cor related to air temperature and precipitation (repp 1979). the concentration of prey organ isms most likely occurs only in periods with high fresh water outflow and may thus be an unreliable food source for the birds due t o possible variations between years. for example, the concentrations found outside nordenskioldbreen in 1933 (hart ley & fisher 1936) were not found in the summers of 1921,1926 and 1937 (f. c. stott, pers. comm.). similarly, seabird foraging activity at austfonna was lower in 1982 than in 1981 (mehlum 1984). kittiwake concentrations at river outlets in kongsfjorden were found in 1983 but not in 1984 diet of high-arctic seabirds 19 (mehlum 1984). we suggest that prey con centrations at river outlets and glacier faces are utilised opportunistically by seabirds in years when these phenomena occur. the high pro portion of parathemisto and thysanoessa found in our coastal samples of the surface feeding kittiwakes may be explained by such opportunistic foraging. concluding remarks we would add that caution should be taken in the interpretation of our results dealing with the relative importance of different prey types in the diet of the six seabird species studied. in table 2 we have for each seabird species pooled the data for all individuals sampled in coastal versus off shore, ice-covered regions (see materials and methods). thus, differences in diet composition among samples sets in each of the two habitat types were not accounted for. furthermore, sample sizes of the single data sets were different, which might bias the averaged frequency of occur rence presented in table 2. these problems were partly eliminated in figs. 2-7, by splitting the data into spring and summer samples. because of this potential bias we did not perform statistical tests for comparing the pooled data sets. because of low sample sizes, we also were careful in our interpretation of differences in occurrence or numerical abundance between single data sets. even though we were not fully able to dem onstrate the variability in the seabirds’ diet from one year to the other and despite the shortcomings of pooling sample sets, our extensive total material should give a reasonable general picture of the main prey types taken by the six seabirds species in the study areas and indicate differences among years and sampling localities. an interesting follow up study would be to investigate the importance of capelin to seabirds foraging in the marginal ice zone in the northern barents sea in years when the stock of this key fish species in the barents sea ecosystem is abundant (sakshaug & skjoldal 1989). acknowledgements. -we thank h. dahlen, i . gjertz, c. lyd ersen, v. ree, and e. soglo for collecting seabirds, and i . gjertz, 0. kaasa, j. koszteyn, 0. j. lbnne, and j. m. wes lawski for help with the analysis of stomach samples. we also want to thank m. konarzewski and j. taylor for providing the material of little auks from hornsund 1987. r. barrett, i. gjertz, 0. j. lbnne, g. l. hunt, and two anonymousreviewers made valuable comments to the manuscript. the study was partly supported by the norwegian research program for mar ine arctic ecology (pro mare) of the norwegian research council for science and the humanities. references aarset a. v. & aunaas, t. 1987: osmotic responses to hypos motic stress in the amphipods gummarus wilkitzkii, onisimus glacialis and parathemisto libellula from arctic waters. polar biol. 7 , 18%193. belopolskii. l. 0. 1957: ecology of sea colony birds of the barents sea. [transl. from russian, 1961. israel prog. sci. tansl., jerusalem.] bradstreet, m. s. w. 1976: summer feeding ecology of seabirds in eastern lancaster sound, 1976. lgl limited, environ mental research associates. toronto, canada. 187 pp. bradstreet, m. s. w. 1980: thick-billed m u m s and black guillemots in the barrow strait area, n.w.t., during spring: diets and food availability along ice edges. can. 1. z o o f . 58, 2120-2140. bradstreet, m. s. w. 1982. pelagicfeeding ecology of dovekies, alle alle. in lancaster sound and western baffin bay. arctic 35,126140. bradstreet, m. s. w. & cross, w. e. 1982: trophic relation ships at high arctic ice edges. arctic 35, 1-12. cairns, d. k. 1987: the ecology and energetics of chick pro visioning by black guillemots. condor 89, 627-635. dalpadado, p. 1989 some observations on moulting, growth and maturation of krill (thysanoessa inermis) from the bar ents sea. 1. plankton res. i ! , 133-139. dalpadado, p. & skjoldal, h. r. 1991: distribution and life history of krill from the barents sea. polar res. 10,443460. de korte, j. 1972: birds, observed and collected by “de ned erlanse spitsbergen expeditie” in west and east spitsbergen, 1967 and 1968’69; first part. beauforria 19, 113-150. diamond, a. w. 1983: feeding overlap in some tropical and temperate seabird communities. studies in aoian biology 8, 24-46. duffy, d. c. & jackson, s. 1986: diet studies of seabirds: a review of methods. colon. waterbirds 9, 1-17. duffy, e. & sergeant, d. e. 1950 field notes on the birds of bear island. ibis 92, 554563. ekman, s. 1953: zoogeography of the sea. sidgwick and jackson. london. 417 pp. franz, h. g. & diel, s. 1984: secondary production of calanus finmarchicus (copepoda: calanoidea) in a transitional system of the fladen ground area (northern north sea) during the spring of 1983. xix embs, plymouth, devon, k. 16-21 september 1984. frost, k. j. & lowry, l. f. 1981: trophic importance of some marine gadids in northern alaska and their body-otolith size relationships. fish. bull. u.s. 79, 187-192. gjertz, i . & lydersen, c. 1986. the ringed seal (phoca hispida) spring diet in northwestern spitsbergen, svalbard. polar res. 4 , 53-56. gjertz, i . , mehlum f. & gahrielsen g. w. 1985: food sample analysis of seabirds collected during the ‘lance’-cruise in ice filled waters in eastern svalbard 1984. norsk. polarinst. rapp. 23. gulliksen, b. 1984: under-ice fauna from svalbard waters. sarsia 69, 17-23. hamre, j. 1988: some aspects of the interrelation between the 20 f. mehlum & g . w . gabrielsen herring in the norwegian sea and the stocks of capelin and cod in the barents sea. lnternational council for the explo ration of the sea. c.m. 1988/h:42, 1-15. (mimeo). harrison, n. m. 1984: predation on jellyfish and their associates by seabirds. limnol. oceanogr. 29, 13351337. hartley, c. h. & dunbar, m. j . 1938: on the hydrographic mechanisms of the so-called brown zones associated with tidal glaciers. j . mar. res. i , 305-311. hartley. c. h. and fisher, j . 1936: the marine foods of birds in an inland fjord region in west spitsbergen. part 2. birds. j . animal. ecol. 5 , 370-389. horn, h. s. 1966: measurement of “overlap” comparative ecological studies. a m . nut. 100, 41w24. hunt, g . l. jr. 1991: marine birds and ice-influenced environ ments of polar oceans. 1. mar. syst. 2 . 233-240. ikeda, t. & skjoldal, h. r. 1989: metabolism and elemental composition of zoo-plankton from the barents sea during early arctic summer. mar. biol. 100, 173-183. loeng, h. 1989: ecological features of the barents sea. pp. 327-365 i n rey, l. & alexander, v. (eds.): proc. 6th conf. of the comitt! arctique int; 13-15 may 1985. e. j . brill. leiden. lydersen, c.. angatyr, l. a,. wiig, 0. & (britsland, t. 1991: feeding habits of northeast atlantic harp seals (phoca groen landica) along the summer ice edge of the barents sea. can. j. fkh. ayuat. sci. 48, 2180-2183. lydersen, c., gjertz, 1. & weslawski, j . m. 1989: stomach contents of autumn-feeding marine vertebrates from hornsund, svalbard. polar rec. 25, 107-1 14. lbnne, 0. j . & gabrielsen, g. w. 1992: summer diet of seabirds feeding i n sea-ice covered waters near svalbard. polar biol. 12,68%92. lsnne. 0. j . & gulliksen, b. 1989: size, age and diet of polar cod, boreogadus saida (lepechin 1773). in ice covered waters. polar biol. 9 , 187-191. lsnne, 0 . j . & gulliksen, b. 1991a: on the distribution of sympagic macro-fauna in the seasonally ice covered barents sea. polar biol. 1 1 . 4 5 7 4 9 . lsnne, 0 . j. & guuiksen, b. 1991b: sympagic macro-fauna from multiyear sea-ice near svalbard. polar biol. 1 1 , 471 477. lbvenskiold, h. l. 1964: avifauna svalbardensis. norsk polarinst. skrifter 129. 460 pp. mclaren, p. & renaud, w. e. 1982: seabird concentrations in late summer along the coasts of devon and ellesmere islands, n.w.t. arctic 35, 112-117. mehlum, f. 1984: konsentrasjoner av sjbfugl langs kanten av isbreer og utenfor breelver pi3 svalbard. fauna 37, 156-160. mehlum, f. 1989: summer distribution of seabirds in northern greenland and barents seas. norsk polarinst. skrifter 191, mehlum f. 1990: seabird distribution in the northern barents sea marginal ice-zone during late summer. polar res. 8, 61 65. mehlum f. & bakken, v. (in press): seabirds in svalbard: status, recent changes and management. in nettleship, d. 1-56. n., burger, j . & gochfeld, m. (eds.): seabirds on islands: threats, case sfudies & action plans. international council for bird preservation techn. publ. cambridge, uk. mehlum f., gabrielsen, g. w. & nagy, k. a. 1993: energy expenditure by black guillemots (cepphus g y l l e ) during chick-rearing. colon. waterbirds 16 (in press). mehlum f. & gjertz 1. 1984: feeding ecology of seabirds in the svalbard area a preliminary report. norsk. polarinst. rapp. 16. melnikov, i. a. & kulikov, a. s. 1980: the cryopelagic fauna of the central arctic basin. biol tsental‘nogo arkticheskogo basseina. pp. 97-111. nauka, moscow. (canadian translation of fisheries and aquatic sciences 4910). nesis, k. s. 1965: distribution and feeding of young squids gonatus fabricii (licht.) in the labrador sea and the norweg ian sea. oceanology 5 , 102-108. norderhaug. m., brun. e. & mbllen, g. u. 1977: bar entshavets sjbfuglressurser. norsk polarinst. medd. 104, 1 119. opalinski, k. w. & weslawski, j. m. 1989: ecology, metabolic rate and metabolic adaptations in spitsbergen amphipods. pol. arch. hydrobiol. 36. 333-350. pettibone, m. h. 1954: marine polychaete worms from point barrow, alaska, with additional records from the north atlantic and north pacific. proc. u.s. nationalmuseum 103, 203-356. pielou, e. c. 1984: the interpretation of ecological data. a primer on classifcation and ordination. wiley & sons, new york, 263 pp. renaud, w. e. & mclaren, p. 1982: lvory gull (pagophila eburnea) distribution in late summer and autumn i n eastern lancaster sound and western baffin bay. arctic 35, 141 148. repp. k. 1979: breerosjon, glacio-hydrologi og materialutslipp i et hbyarktisk miljb, brbggerbreen, vest-spitsbergen. upubl. ph.d. thesis, univ. oslo (in norwegian). sakshaug, e. & skjoldal, h. r. 1989: life at the ice edge. ambio 18, 60-67. vinje, t. 1985: drift, composition, morphology and distribution of the sea ice fields in the barents sea. norsk. polarinst. skrifter 179c. 26 pp. weslawski, j . m. 1987: distribution of decapoda (crustacea) in south spitsbergen coastal waters with remarks on their ecology and breeding biology. polish polar res. 8. 121-134. weslawski, j. m. & kwasniewski 1983: application of bio logical indicators to determine the reach and origin of sea currents within the region of spitsbergen. pol. arch. hyd robiol. 30, 189-197. wing, b. l. 1976: ecology of parathemisto libellula and p. pacifca (amphipoda: hyperiidea) in alaskan coastal waters. northwest fisheries center, auke bay fisheries laboratory, processed report march 1976. noaa. zelickman, e. a. & golovkin, a. n. 1972: composition, structure and productivity of neritic plankton communities near the bird colonies of the northern shores of novaya zemlya. marine biology 17, 265-274. por_008.fm 64 polar research 26 (2007) 64 – 75 © 2007 the authors just over a century ago, the american journalist walter wellman first tried to reach the north pole by airship. despite the hoopla that surrounded the expedition, it was a fiasco and the attempt became a quirky and somewhat obscure episode in the history of polar exploration. in this issue of polar research, we present two complementary contributions about this event. the first paper, below, is a collaboration between penn state university abington college archaeologist p. j. capelotti, engineer and airship historian herman van dyk and swiss aeronautical historian jean-claude cailliez. it presents new data on the initial operations of wellman’s attempt to reach the pole in 1906. —the editor keywords north pole; wellman; nansen; savlbard; airship; motor sledge; zeppelin. capelotti et al . correspondence p. j. capelotti, division of social and behavioral sciences, penn state university, abington college, abington, pa 19001, usa. email: pjc12@psu.edu doi:10.1111/j.1751-8369.2007.00008.x b i o g r a p h i c a l / h i s to r i c a l e s s ay strange interlude at virgohamna, danskøya, svalbard, 1906: the merkelig mann , the engineer and the spy p. j. capelotti, 1 herman van dyk 2 & jean-claude cailliez 3 1 p. j. capelotti, division of social and behavioral sciences, penn state university, usa 2 7 birchwood avenie, peabody, ma 01960, usa 3 75 avenue de mategnin, ch-1217 meyrin, switzerland between 1894 and 1909, the american journalist walter wellman (fig. 1) organized and led five expeditions in search of the geographic north pole (barr 1980; capelotti 1999a, 2006; baldwin 2004). wellman launched his most ambitious undertaking in 1906, constructing an extensive base camp complete with an airship hangar on the shoreline of virgohamna, on the island of danskøya in the svalbard archipelago, in plain view of the ruins of the balloon shed used a decade earlier by the swede salomon august andrée during his polar balloon expeditions (barr 1980; capelotti 1994, 1997, 1999b; see map in diesen & fulton 2007). this paper examines three previously unexplored aspects of the operations at wellman’s 1906 base camp. first, we examine the design and construction of a polar motor sledge planned as an emergency vehicle in case the airship crashed on the polar ice pack. second, we look at the design and construction by the swiss engineer alexandre liwentaal of the great hangar necessary to shelter the airship while it was being assembled, inflated and readied for its polar flights. lastly, the interests in wellman’s aeronautical explorations by an expansionist german empire are noted. wellman returns to svalbard, 1906 in late 1905, wellman convinced victor f. lawson, owner of the chicago record–herald , to pledge $75 000 toward the construction of an airship similar to the frenchdesigned lebaudy . this new airship would be capable of carrying a small band of explorers to the as yet undiscovered north pole. by march 1906, wellman had subscribed the support of the national geographic society, the french academy of science, and even president theodore roosevelt himself. eventually, wellman raised a quarter of a million dollars. this monumental sum enabled the construction in paris of a polar airship and, on the remote island of danskøya in north-west svalbard, barely 1000 km from the north pole, of a large hangar and expedition base camp (see map in diesen & fulton 2007). why wellman chose virgohamna for his airship base camp is not clear. he had visited svalbard once before, when he first attempted to reach the north pole in 1894. this sledge expedition was halted when its support ship, the ragnvald jarl , was nipped and sunk by ice along the shores of waldenøya. during this expedition, wellman had stopped to use the house owned by the british hunter, arnold pike, at virgohamna (see capelotti 1997: 11). wellman later claimed that he had formed the idea of using an aerial machine to reach the pole even before salomon andrée (wellman 1911: 35–39). whatever the truth of this claim, wellman sought in vain to locate the lost andrée during his 1898–99 franz josef land expedition. as a journalist, he was most certainly aware of the publicity that would attach to any such discovery (for p. j. capelotti et al. strange interlude at virgohamna, danskøya, svalbard, in 1906 polar research 26 (2007) 64 – 75 © 2007 the authors 65 example, see wellman 1898; baldwin 2004: 9–10). so it is logical that he would seek to use virgohamna for the existing infrastructure (pike’s house), for whatever supplies the andrée expedition had left behind and for the notoriety of the site on account of its associations with the andrée mystery. at the national geographic society, the motion to support wellman’s 1906 polar expedition was moved by the inventor alexander graham bell—after whom wellman had named an island in franz josef land in 1899 (see capelotti 2006). the society appointed a major henry e. hersey to lead a scientific party. like evelyn briggs baldwin, wellman’s second-in-command on the franz josef land expedition, hersey, was a meteorologist for the us weather bureau. he became the construction supervisor for the virgohamna base camp. wellman’s airship was designed and constructed in paris late in the spring of 1906 by the firm of louis godard. parisian engineers had given wellman conflicting advice on what type of airship possessed the best chance to reach the north pole. one faction argued for a fast airship that could make a quick trip to the pole without touching the earth. the other faction, whom wellman described as the ones who advocated “safety and sanity”, argued for an airship with a trailing ballast tube filled with reserve provisions ( new york times , 11 march 1906). through its trailing ballast tube, called an equilibrator, this airship would keep in constant touch with the earth, at an altitude between 33 and 100 m, depending on factors like changing atmospheric conditions, the amount of hydrogen gas used and the amount of petrol and other supplies consumed. even though wellman had analysed fridtjof nansen’s data on wind speeds over the polar ocean and concluded that in the months of july and august there would be on average only 5 hours out of every 10 days when the airship would confront winds of more than 17 miles (27 km) per hour (wellman 1911: 161–162), wellman sided with the “safety and sanity” school. in retrospect, wellman should have paid more attention to his analysis that showed that the airship would face winds of less than 11.2 km per hour nearly 50% of the time. a fast airship, even in 1906, could have reached the pole and returned to virgohamna in less than 2 days. by choosing slow safety over rapid risk, wellman spiked his own dream of an airship that could reach the north pole and return in one swift, thrilling round-trip expedition. at the same time as these decisions were being made, a strange motor sledge was also being designed and built in paris. wellman announced his various intentions to use motor sledges in his programme when he returned to new york from pre-expedition meetings in europe in march 1906. in the new york times (11 march 1906), wellman expressed the idea that he might land and collect scientific data on the polar ice cap at places other than the north pole. for this purpose, as well as to return back to his base camp from a potential forced landing of the airship, the exploring party would have “four motor sleds which weigh 210 pounds [95.25 kg] each”. just 2 weeks later, these four sledges were reduced to two in a speech to the new york motor club on 23 march 1906. in this speech, he admitted that the slow godard airship would not carry enough fuel to allow him to make a return trip after reaching the pole. wellman said that he had solved this problem by the expedient of commissioning the construction of two motor sledges, one in europe and one in the usa, each weighing 210–215 lbs (95.25–97.52 kg). they would be equipped with small engines and carry two persons each. if his tests were successful, wellman expected to take the two motor sledges on board the airship with him. as for the new airship, it ultimately proved a total failure. the engines could not be made to perform properly, and the expedition was promptly cancelled in august 1906. the hangar was secured for the winter and a party of three men left in charge. in wellman’s view, he figure 1 walter wellman in kristiania (oslo) in the late spring of 1906. he is standing in the deck of the 1906 godard-designed and -built polar airship. (courtesy of library of congress.) 66 polar research 26 (2007) 64 – 75 © 2007 the authors strange interlude at virgohamna, danskøya, svalbard, in 1906 p. j. capelotti et al. had just launched “the first effort to put aerial navigation to actual use in the performance of valuable scientific work” (wellman 1911: 14). others disagreed. in the view of fridtjof nansen, wellman had merely created at virgohamna a “common looting place for tourists and others looking for souvenirs” (nansen 1920: 144; translations from en ferd til spitsbergen were made by bjarne petterson in 1994). by the 1990s, possibly due to nansen’s dismissal of wellman as “this great humbug” (nansen 1920: 145), wellman’s daring expeditions had been largely forgotten in norway. the merkelig mann: wellman’s arctic motor sledge in the aerial age (1911), wellman wrote not of the sledges weighing 210–215 lb (95.25–97.52 kg) that he had described to the new york times and new york motor club in march 1906, but of “a light vehicle, weighing only 150 or 200 pounds [68–91 kg] [which] two men could easily lift . . . over the hummocks and ridges” of the polar ice pack (wellman 1911: 120). this lightweight motor sledge would “be used, not to carry loads, but to pull them. it was to be a little locomotive, drawing its string of lightlyloaded sledges behind it” (wellman 1911: 120). it is not known who built wellman’s motor sledge in france. according to wellman, his theory was sabotaged by incompetent workers he identifies only as “assistants”: i was compelled to go to america and to leave the details in the hands of assistants. they built the sledges far too heavy—good for work on smooth ice, as they proved when tested out on the lakes of norway, but useless upon the rough ice of the polar ocean. (wellman 1911: 133) the earliest depiction of wellman’s motor sledge can be seen in an illustration of his airship, made before the airship was actually built (fig. 2). it shows two motor sledges on top of the framework of the car, immediately in front of, and behind, the crew compartment. the annotations on this drawing are all in english, which suggests that the illustration was drawn in the usa. however, this does not necessarily mean that the picture shows the american-designed version of the motor sledge. although the image is only a few millimeters long, it clearly shows that the design concept is similar to that of a photograph of the sledge constructed in france. the main difference is that the drawing shows one seat, perhaps for two people sitting side by side, while the actual sledge as constructed in france had tandem seating. also, steering seems to have been accomplished by a bicycle-type handle-bar, rather than a steering wheel. the drawing seems to show a backrest as well as armrests; the actual sledges as constructed appear not to have been that comfortable. no drawing of the american version of wellman’s planned motor sledge has survived, so it is unknown if it was ever built. but three photographs have been uncovered of the french version. the first, a fuzzy side-view that appeared in wellman’s newspaper, the chicago record–herald , was used by van dyk in 1997 to make a design drawing of the likely components of the motorsledge (fig. 3). a second photograph, also a side view, was found by capelotti in the archives of the norwegian museum of cultural history in oslo (fig. 4). it shows the motor sledge in a state of assembly. the only new detail revealed by this image was that both seats were provided with a cushion or pillow. in the spring of 2006, the svalbard guide andreas umbreit located a new and oblique view of this same vehicle (fig. 5). this photograph, taken by mons. m. branger in paris in 1906, filled in most of the missing details of design and construction, allowing a complete detailed drawing to be made (fig. 6) which served as a basis for the construction of a scale model. the overall length of the motor sledge was 3.3 m and the width was 1.4 m. the diameter of the drive wheel was 1 m, and its width was 40 cm. figure 2 drawing of the 1906 airship showing two motor sledges mounted on top of the airship car, with a detail of the motor sledge. (drawing by van dyk, after popular mechanics 1906: 701–703.) p. j. capelotti et al. strange interlude at virgohamna, danskøya, svalbard, in 1906 polar research 26 (2007) 64 – 75 © 2007 the authors 67 the motor sledge consisted of an h-shaped wooden frame which carried all components, including the engine, two seats, fuel and oil tanks, and storage space. the two longitudinal main beams were supported at the front by a single drive wheel and in the centre by a pair of skis or runners. both ends of each main beam were shaped into handles, so that four strong individuals could carry the sledge onto, or from, the airship car. for traction on snow and ice, there were two rows of 12 ridges, consisting of short pieces of angle iron, bolted in a vpattern to the rolling surface of the drive wheel. in between the ridges were four rows of 12 spikes. the frame of the driver’s seat was a simple rectangular structure attached to the two main beams. the actual sitting surface consisted of two wooden boards. in front of the driver were the steering wheel and engine controls. the floorboards of the front seat were slightly raised to accommodate the control and drive mechanisms. the driver’s seat was located in the middle of the frame and, behind that, was the fuel tank, mounted against the back of the driver’s seat. the space underneath the passenger’s seat was used for storage. located between the main beams and below the driver’s seat was the engine and, in front of it, the transmission box with sprocket gear for the chain to the drive wheel. a flywheel was mounted on the right end of the crankshaft. the oil tank was directly below the driver’s seat. an exhaust tube led from the left side of the engine down and to the rear of the sledge to a figure 3 design drawing of the 1906 motor sledge, reconstructed by van dyk from a photograph published in the chicago record–herald , 30 june 1906. (1) manouevring handle; (2) storage area; (3) rear seat; (4) fuel tank; (5) front seat; (6) engine; (7) oil tank; (8) filter; (9) steering wheel; (10) cleats; (11) sprocket wheel; (12) pillow block; (13) drive wheel; (14) roller chain; (15) gear box; (16) flywheel; (17) frame; (18) pivot; (19) suspension spring; (20) runner. figure 4 the 1906 motor sledge at virgohamna, 1906. (courtesy norwegian museum of cultural history [norsk folkemuseum].) 68 polar research 26 (2007) 64 – 75 © 2007 the authors strange interlude at virgohamna, danskøya, svalbard, in 1906 p. j. capelotti et al. muffler. by sitting sideways, the passenger might have been able to warm his cold feet on it. a crossbar, extending to the left and right, was mounted, via a set of suspension springs, to the main beams. at each end, it formed a pivot holding the skis, which were connected by a linkage to the steering wheel. the photographs show some type of a fitting on the left side of the drive wheel. it could have been a means to fill the drive wheel with water to add weight and improve traction. surrounded by snow and ice, it would have been a near-impossible task. the design of the motor sledges was not efficient and wellman discarded the idea of using them on his airships of 1907 and 1909. the force required to move an object over a surface depends on its weight (mass), the friction coefficient between the object and the surface it is resting on, and the speed. once an object is in motion, it requires figure 5 photograph of the 1906 motor sledge, uncovered by andreas umbreit. (courtesy of andreas umbreit.) figure 6 new design drawing of the 1906 motor sledge, reconstructed by van dyk from the photograph uncovered by andreas umbreit. p. j. capelotti et al. strange interlude at virgohamna, danskøya, svalbard, in 1906 polar research 26 (2007) 64 – 75 © 2007 the authors 69 only a very small side force to make it move in a different direction. modern snowmobiles have the weight of the engine, passengers, fuel, etc., resting on a drive belt (wheel) to maximize traction. only a little weight is on the skis, to facilitate steering. wellman’s sledge, however, had most of the weight resting on the skis, which was to be used for steering, and only a little weight on the drive wheel which was to provide traction. to nansen, wellman was an “odd man” ( merkelig mann ) whose airship expeditions were essentially advertising schemes that demonstrated how the attention of the world’s press could be held, year after year, despite there being nothing of value to report (1920: 145; see diesen & fulton 2007). nansen reserved special scorn for wellman’s idea to design, build and employ motor sledges on his planned 1906 airship expedition, as well as the notion of using a trailing ballast tube—the “equilibrator”—to stabilize the airship and hold several hundred pounds of reserve supplies. in his book, en ferd til spitsbergen ( a journey to spitsbergen ; 1920), nansen derided the idea of the equilibrator as a trailing “sausage” and the motor sledges as the work of a fool who had not thought through how he would fuel them on the return journey from the pole: the lower part of the sausage should be dragged along the ice. it was possible pieces of it would fall off, especially when some of them got jammed into the pack ice. but these pieces would then be left where they fell and would serve to mark the way where they had travelled. if the airship, for one or another reason, should go down, then those daring travellers, when they came driving back on the motor sledges they did not have yet, could easily find their way back by following these sausage-like pieces. and besides, they could live off off their contents. one important thing was missing, though. they didn’t have any gasoline to keep their engines going. (nansen 1920: 142) nansen’s critique notwithstanding, wellman was the first explorer to bring an overland (or over-ice) motor transport machine into the polar regions. a norwegian museum of cultural history photograph (fig. 4) shows the motor sledge, minus its enormous drive wheel, sitting on the shoreline of virgohamna in the summer of 1906 as the airship hangar is being constructed. since wellman only writes of testing the sledge on a lake in norway (perhaps lake mjøsa, in southern norway, where robert falcon scott would later test his antarctic sledges (see the fascinating description of this testing in diesen & fulton 2007), the folkemuseet image is the only evidence that his motor sledge was actually transported to virgohamna in anticipation of the polar expedition of 1906. other polar explorers, like scott, would not begin to consider the possibilities of polar travel with motor sledges until the fall of 1906 (fiennes 2003). it is not known if wellman ever attempted to use his motor sledge at virgohamna, but given the uneven and rocky terrain, this seems unlikely. the engineer: liwentaal’s polar airship hangar soon after the completion of the airship and motor sledge in paris, wellman sent major hersey north to establish a base camp in north-western spitsbergen, on the shores of virgohamna on danskøya (fig. 7). for a week, hersey blasted away at the rock and ice at virgohamna until he had cleared an area nearly the size of an american figure 7 the hangar and airship under construction, virgohamna, 1906. the person standing in front of the propeller blade is most likely walter wellman. (courtesy norwegian museum of cultural history [norsk folkemuseum].) 70 polar research 26 (2007) 64 – 75 © 2007 the authors strange interlude at virgohamna, danskøya, svalbard, in 1906 p. j. capelotti et al. football field for the floor of the airship hangar. the virgohamna site was adjacent to the remains of the abandoned balloon shed from which andrée attempted to fly to the pole in 1897. for the floor of wellman’s hangar, hersey made use of the timbers surviving from andrée site. “thus again”, wrote wellman, “was the site of andree’s ill-fated enterprise to be the scene of strange activity” (wellman 1911: 146). hersey brought with him not only “three or four hundred tons [272 155 – 362 874 kg] of timber and iron” for the hangar and ancillary buildings, but 125 tons (113 398 kg) of sulphuric acid and 75 tons (63 503 kg) of scrap iron filings, which, when combined by 30 tons (27 216 kg) of “apparatus and other chemicals”, produced hydrogen for the airship (wellman 1907: 199). in addition to this enormous load, which required three round trips to and from tromsø by the frithjof , camp wellman was outfitted with “half a ship-load of provisions; the aeronautic machine and all its appurtenances: dogsledges, motor-sledges, a steam boiler and engine, tons of gasoline, tools, coal, iron rods, bolts, nails, steel boats, and all the paraphernalia of what a london periodical aptly termed ‘mr. wellman’s scientific village in the arctics’ ” (wellman 1911: 154). there was also a forge for molding the iron rods that would stay the wooden arches of the hangar. other structures included a machine shop with lathes, drills, and other machine tools; the boiler house, steam engine, steam pump; and, finally, the building containing the gas apparatus to inflate the airship. the main building, which served as wellman’s headquarters, housed 40 scientific staff, engineers, aeronauts, mechanics, sailors and workmen. one of these was the swiss engineer alexandre liwentaal, the man responsible for building the airship hangar. since hersey was a meteorologist, it is very likely that the supervision of the hangar construction was left to liwentaal, whom wellman described in the aerial age as both an architect and an engineer (1911: 131, 153) and, in a 1906 article, as someone who had been “associated with count zeppelin in the famous airship experiments in germany and switzerland” ( new york times , 24 april 1906). when wellman arrived on danskøya, several weeks behind major hersey and full of expectation at the thought of steaming into the harbor and seeing the huge hangar, he was greeted instead by only the splintered remains of andrée’s balloon shed. wellman had budgeted $10 000 for construction of the hangar ( new york times , 11 march 1906), and was perturbed that it was not further along than he felt it should be. “our force of men worked hard all summer, but were unable to finish the balloon house and the other buildings in time to make it possible to inflate the airship and get it ready for a voyage. the engineer liwentaal had undertaken to complete the balloon house within three weeks after reaching our base. it was all he could do to finish it in nine weeks” (wellman 1911: 153). liwentaal’s own notes show that he finished the hangar in 6 weeks, but only after wellman intervened in its construction. liwentaal (fig. 8) had worked for several balloon and airship designers around the turn of the century before signing on with the wellman polar expedition in 1906. he worked in paris for lachambre, the builder of andrée’s balloon, from 1895 to 1898, for the lebaudy airship works in 1903, and did two stints with count ferdinand von zeppelin (1899–1900; 1904–05). rather than construct a hydrogen generator plant at virgohamna, liwentaal had attempted to purchase hydrogen in cylinders from zeppelin, but germany had put the strategic material under an export embargo. under liwentaal’s supervision, on 13 july 1906, a team of 25 norwegian workers hired from trondheim, tromsø and hammerfest began to lay the foundation and put down the floor of the hangar. this crew included paul bjørvig and olaf ellefsen, who had been members of the figure 8 camp wellman, virgohamna, 1906. cailliez identifies the man as the swiss engineer alexandre liwentaal. (courtesy norwegian polar institute.) p. j. capelotti et al. strange interlude at virgohamna, danskøya, svalbard, in 1906 polar research 26 (2007) 64 – 75 © 2007 the authors 71 1898–99 wellman expedition to franz josef land (see baldwin 2004). the structure was not completed until 28 august, and then only because wellman ordered liwentaal to reduce the number of supporting eight-story-high arches from nine to five (fig. 9). as liwentaal explained: the problem was both difficult and very interesting. we were to build, on the borders of the polar icebarrier, a complete aeronautical building site, including the hangar of the airship whose dimensions were: length: 58 m; height: 26 m; width at base: 25 m. as the boreal summer is very short, lasting hardly two months, it was necessary to build the structure quickly. in addition, navigation in the ice-barrier can only be done by a few specialized ships, of small tonnage, whose carrying capacity is further decreased by the ship’s hull being one metre thick. it was impossible to place on board any wood that was more than 4 m in length, nor to load more than 40 m 3 on board. it was thus necessary to design the hangar in order to build with the most reduced minimum of supplies and to organize the construction work at a rate compatible with the voyages of the ship. these data determined the type of hangar, which was considered an elegant solution of the problem, and so construction was begun on 13 july 1906 and was finished on 28 august of the same year. the characteristic of our method is to employ green heart [a dense wood used in european wharf construction], which was very advantageous, to bind it place by means of hoists, then to bolt and brace these sections to preserve the form given to him. the advantages that resulted from this process were: great facility of work, speed of construction, great saving in materials, and the maximum strength against wind resistance. (cailliez 2004: 108–109; translated by the authors) as chief engineer for the hangar construction, liwentaal joined together his control of the art of wood-working with his mathematical skill. his competence was put to the test to create a hangar nearly 30 m high, which could hold back several years of blizzards and high winds. despite his impatience with the delays, wellman recognized the difficulty of this work. this balloon house was no small job. it had to be built of arches fashioned on the spot, bent and bolted together on bending frames. as fast as the arches were finished they were raised by means of a huge pyramid or derrick manned by a score of men. when the arches were all up they were moved to their proper places and bridges or spans thrown across to bind them together. the whole was covered with nearly an acre of strong canvas prepared in norway for the purpose. the structure was 210 feet [64 m] long, 85 feet [26 m] wide and 85 feet high. the floor was completely covered with boards. (wellman 1911: 153–154) wellman noted that the hangar would never have been finished in the summer of 1906 if he had not taken the step of reducing the arches from nine to five (fig. 10). this no doubt led to the damage the structure suffered in a july storm in 1907. the hangar was rebuilt, collapsed again in the winter of 1908–09, was rebuilt a third time (fig. 11) and survived three more winters until collapsing finally in 1912. it survives today as easily the largest and most complete archaeological remnant at virgohamna (fig. 12), and was surveyed by capelotti in 1993. the remains of the hangar are located to the south-east of the base camp’s machinery spaces, and are surrounded by at least 48 rock piles and guy stakes that anchored guy wires that once supported the structure. the 1912 collapse created a twisted and chaotic assemblage of foundation beams, deck planks, and arch beams and wires. in several places, especially toward the rear of the hangar, sections of the original deck planks can be seen, and evidence of a limited amount of charring from fires is apparent. the rearward beams are the most intact, with the beams progressively more deteriorated as one moves toward the front of the hangar. it appears that when the hangar collapsed in 1912, it fell from back to front, or figure 9 the liwentaal airship hangar under construction at virgohamna in 1906. the graceful arches and intersecting diamond supports were constructed by forming green heart around bending frames. these frames could still be seen during an archaeological survey of virgohamna in 1993. (from cailliez 2004.) 72 polar research 26 (2007) 64 – 75 © 2007 the authors strange interlude at virgohamna, danskøya, svalbard, in 1906 p. j. capelotti et al. south to north, since the forward-most of the nine arches now lies nearly 35 m from the front of the hangar itself. from the ridges that surround the site on the east, west and south-west, the outline of the hangar appears much more clearly than it does on the ground, where the weathered grey wood seems to blend in with the surrounding grey shoreline rock. piles of deck planking were observed at the rear of the hangar, suggesting that systematic removal of parts of the hangar has taken place at some point or points after wellman abandoned it. for example, george binney’s oxford university arctic expedition in 1921 salvaged wood from wellman’s hangar to build a seaplane slipway at liefdefjorden (binney 1925: 70). wellman’s own measurements of this structure placed it at 24.994 m (82 feet) wide and 57.912 m (190 feet) long. measurements in 1993 differed slightly from this: the width of the hangar ruins is 28.042 m (92 feet), and the length is 56.998 m (187 feet). the freshwater spring that wellman had diverted around the western side of the hangar to the machinery and boiler areas has resumed its course directly under the hangar, with the inevitable rotting and disintegration of the foundation beams, especially at the north-east corner of the hangar, which rests above the same boggy area near to where the remains of the 1906 airship car are located. the spy: captain von gottberg drinks too much whisky neil fulton and jan anders diesen recently discovered a short silent motion picture film that includes scenes of the wellman expedition at virgohamna (diesen & fulton 2007).wellman is seen paying homage at the monument to salomon a. andrée, and doffing his cap to the camera as he leaves on a small boat to board what is likely the german steamer express under the command of “captain theodore lerner, a well-known arctic traveler and figure 10 the liwentaal airship hangar at virgohamna in 1906. (note for scale the man standing next to the second arch from the left.) repairs to this structure delayed the first flight of an airship in the polar regions until 2 september 1907. (from cailliez 2004.) figure 11 the hangar, rebuilt for the 1909 expedition with nine supporting arches, and without the diamond-shaped supports made by liwentaal in 1906. (from wellman 1911.) p. j. capelotti et al. strange interlude at virgohamna, danskøya, svalbard, in 1906 polar research 26 (2007) 64 – 75 © 2007 the authors 73 sportsman” (wellman 1911: 150). a photograph of this scene appears in a new account of lerner’s adventures (lerner 2005: 117). there were several german connections to the 1906 expedition. liwentaal had tried and failed to purchase hydrogen in cylinders from zeppelin, while the sulphuric acid for the manual production of hydrogen at virgohamna was purchased from a firm called reher amd ramsden in hamburg. but the strangest connection came when wellman arrived at virgohamna to find a green tent on the shore above which flew a german flag. wellman was told that the occupant of the tent was a german journalist who claimed he knew the american. wellman soon found himself reunited with an otto von gottberg, whom wellman described “a famous correspondent representing the berlin lokal anzeiger ”. it was gottberg who had chartered the steamer express under the command of theodore lerner. herr von gottberg was at first very anxious lest i should not permit him to remain, having absorbed from american papers the false notion that we were working this expedition as an advertising affair, and that therefore we might not wish the representatives of other newspapers to be present to get information. we quickly informed him of his error and of the fact that he was welcome to stay as long as he wished. (wellman 1911: 150–151) but liwentaal later suggested a more sinister motive for gottberg’s visit. in 1917, liwentaal wrote a series of sketches of zeppelin, whose machines were at that time menacing england, for the london sunday–chronicle (liwentaal 1917). liwentaal claims that gottberg, whom he names “golberg”, was in fact a retired officer who had been sent to virgohamna by the german general staff “to watch our proceedings”. liwentaal describes him as a very pleasant individual, fluent in six languages and wellsuited to his mission with one exception: “he took too much whisky”. liwentaal writes of the fear the germans felt at the potential of other nations to control “the empire of the air”. liwentaal admitted that he himself was slow to recognize german military ambition, but that the visit to virgohamna in 1906 convinced him that germany was serious in its intentions to expand german power in europe, by force if necessary. when von gottberg drank too much, he was always insisting on the greatness of the german empire. one day when i had treated his boastfulness somewhat lightly he broke out furiously: “yes. we will make war when we think the moment has arrived. we shall over-run belgium and jump on france unawares. we shall get to paris in a fortnight, and settle france in a month. then we shall take the french navy and destroy britain”. (liwentaal 1917) in his account of the incident for the london sunday– chronicle , liwentaal relates that wellman simply laughed at this. liwentaal felt that an englishman might have laughed at it as well in the summer of 1906. but liwentaal had worked personally for zeppelin. he felt sure that gottberg’s presence at wellman’s base camp was calculated to find more than a good story; rather, it was a mission to locate anything which might be used for the german war machine. liwentaal’s suspicions might be supported by one of the images stored at the norwegian museum of cultural history (fig. 4), which seems to show several german officers examining wellman’s disassembled motor sledge at virgohamna. liwentaal further believed that gottberg’s reports on the wellman expedition “apparently gave to the german staff the idea that our work required complementary investigations” (liwentaal 1917). in this he was partly correct, since zeppelin himself, along with the meteorologist hergesell, would later investigate svalbard as a base for airship operations. figure 12 the remains of the airship hangar at virgohamna, 1993. (photo by p. j. capelotti.) 74 polar research 26 (2007) 64 – 75 © 2007 the authors strange interlude at virgohamna, danskøya, svalbard, in 1906 p. j. capelotti et al. aftermath: war, lies and the gulf stream wellman himself never mentioned the incident with von gottberg in his exploring memoir, the aerial age , published 3 years prior to the start of the first world war. he does, however, end the book with a plea to the us government to develop a fleet of airships to serve as an aerial defense force for the coastlines of the american continent. wellman’s expeditionary airship, america , which failed so badly at virgohamna in august 1906, was extensively modified by an itinerant aeronaut and photographer named melvin vaniman for another attempt on the pole from virgohamna in 1907. vaniman scrapped the original louis godard car and designed and built one of his own (van dyk 1996). vaniman modified america yet again for a third try by airship in 1909. wellman’s two flights in the america in 1907 and 1909 marked the first time that a motorized airship had flown in the arctic. in july 1909, 1 month prior to wellman’s final attempt to reach the pole through the air, zeppelin announced his own intention to reach the north pole in an airship. this bold plan was curtailed by doubts about the infrastructure in svalbard to handle such an expedition, by the american claims to the pole later that year and, soon, by preparations for aerial war in europe. in september 1909, the american polar explorers robert peary and frederick cook both falsely claimed to have reached the north pole—cook in 1908 and peary in 1909. this news discouraged not only zeppelin, but also wellman, who abandoned the camp at virgohamna and turned his aeronautical ambitions instead to crossing the atlantic ocean. in october 1910, wellman built a new airship for an attempt to reach europe from america by an airship voyage across the north atlantic. taking off from atlantic city, new jersey, wellman flew in a huge arc past cape cod before north-east winds pushed the airship southwards. the expedition continued for several days and over 1600 km—nearly the distance from virgohamna to the north pole and back—before engine trouble forced the merkelig mann and his crew to abandon ship not far from bermuda. a passing steamer delivered wellman and his crew back to shore. before abandoning the airship, the crew punched holes in the large fuel tank, and wellman thought that the airship must have sunk to the bottom of the atlantic ocean soon after. but van dyk uncovered two articles that might tell a different story. a new york times article (21 may 1911) reported that on 21 december 1910, “officers of the russian steamship heros were of the opinion that they sighted the remains of the wellman airship east of the bahama islands. they described the object as a long floating shape, high in the centre, and dropping off at the ends”. if this sighting is accurate, america drifted south from bermuda throughout october, still aloft, but gradually losing its lifting power, until finally settling into the ocean somewhere near the bahamas in november or december. even more interesting, a report from the times of london (22 may 1911) stated that a few days earlier, in clear weather, the white star liner celtic had passed what appeared to be the remains of an airship some 995 km west of fastnet, the small island that is the southernmost point of the republic of ireland. this sighting would appear to corroborate the russian sighting of december, and indicate that the airship america had in fact crossed the atlantic, albeit as flotsam. if true, the wreck of america lies somewhere off the west coast of ireland, the first aircraft to make the journey from the new world to the old. that it accomplished this feat for the most part unmanned and underwater is somehow a fitting final tribute to the aeronautical career of its adventuring captain. acknowledgements for kindly sharing the results of their research, the authors wish to thank the german polar guide andreas umbreit, as well as neil fulton and jan anders diesen of the department of television and film at lillehammer university college. additional thanks are due to dr susan barr of riksantikvaren in oslo, and to ms jeannette ullrich of the penn state university abington college library. references baldwin e.b. 2004. the franz josef land archipelago: e. b. baldwin’s journal of the wellman polar expedition, 1898–1899 . p.j. capelotti (ed.). jefferson, nc: mcfarland. barr s. 1980. virgohamns historie. et øde, uhyggelig sted, en ukoselig bukt. (the history of virgohamna. a desolate, eerie place, a dismal bay.) svalbardposten 17–80/81 , 6–7. binney g. 1925. with seaplane and sledge in the arctic . london: hutchinson & co. cailliez j.-c. 2004. alexandre liwentaal, pionnier suisse de l’aéronautique européenne. (alexandre liwentaal, swiss pioneer in european aeronautics.) geneva: editor secavia. capelotti p.j. 1994. a preliminary archaeological survey of camp wellman at virgohamn, danskøya, svalbard. polar record 30 , 265–276. capelotti p.j. 1997. the wellman polar airship expeditions at virgohamna, danskøya, svalbard; a study in aerospace archaeology. meddelelser 145 . oslo: norwegian polar institute. capelotti p.j. 1999a. by airship to the north pole: an archaeology of human exploration . new brunswick, nj: rutgers university press. capelotti p.j. 1999b. virgohamna and the archaeology of failure. in u. wråkberg (ed.): centennial of s.a. andrée’s p. j. capelotti et al. strange interlude at virgohamna, danskøya, svalbard, in 1906 polar research 26 (2007) 64 – 75 © 2007 the authors 75 north pole expedition. proceedings of a conference on s.a. andrée and the agenda for social science research of the polar regions. bidrag till kungliga svenska vetenskapsakademiens historia 28 , 37–52. capelotti p.j. 2006. e. b. baldwin and the american– norwegian discovery and exploration of graham bell island, 1899. polar research 25 , 155–171. diesen j.a. & fulton n. 2007. wellman’s 1906 polar expedition: the subject of numerous newspaper stories and one obscure film. polar research 26 , 76–85. fiennes r. 2003. captain scott . london: hodder & stoughton. lerner t. 2005. polarfahrer: im banne der arktis. (polar traveller: spellbound by the arctic.) f. berger (ed.). zurich: oesch verlag. liwentaal a. 1917. germany’s long preparations for war. london sunday–chronicle , 27 january. nansen f. 1920. en ferd til spitsbergen. (a journey to spitsbergen.) kristiania: jacob dybwads forlag. new york times 1906. pole hunter’s airship to be ready in may. 11 march, p. 7. new york times 1906. will reach the pole by airship—wellman. 24 april, p. 11. popular mechanics 1906. wellman airship expedition. vol. 8, no. 7. pp. 701–703. times of london 1911. a derelict airship. 22 may, p. 16a. van dyk h. 1996. the evolution of the wellman/vaniman airships. parts 1–3. jack knight air log–the zeppelin collector , january, april, july. wellman w. 1898. where is andrée? mcclure’s magazine 10 , 422–426. wellman w. 1911. the aerial age . new york, ny: a.r. keller. por_006.fm polar research 26 (2007) 31 – 36 © 2007 the authors 31 c.m. glahder et al. eastward moult migration of non-breeding pink-footed geese ( anser brachyrhynchus ) in svalbard christian m. glahder, 1 anthony d. fox, 2 mark o’connell, 3 martin jespersen 1 & jesper madsen 1 1 national environmental research institute, university of aarhus, department of arctic environment, roskilde, denmark 2 national environmental research institute, university of aarhus, department of wildlife ecology and biodiversity, rønde, denmark 3 university of west of england, hartpury, gloucestershire, uk abstract six adult male pink-footed geese ( anser brachyrhynchus ), tagged with satellite transmitters, were tracked in svalbard during the period of june–september in 2003 and 2004. the purpose of the study was to describe the movements and staging periods of individual geese during the post-breeding period to investigate a possible moult migration among pink-footed geese in svalbard. all geese moved about 200 km east from their potential breeding (summering) areas in western spitsbergen. the preferred moulting area was the island of edgeøya, where four geese staged prior to a southward autumn migration. five geese left potential breeding areas between 11 and 30 june, and remained for more than 25 days in eastern areas during most of july, which we interpret as the moult migration of either failed or non-breeders. geese left moulting areas in mid-august, using an average of 1.4 staging areas before the autumn migration, suggesting that moult sites support pre-migration hyperphagia. only one goose remained at the suspected breeding site from early june to early september. mean monthly temperatures in the summering and moulting ranges of the geese were calculated from moderate resolution imaging spectroradiometer (modis) satellite data. the mean june moult range temperature ( − 0.9 ° c) was significantly lower than that of the summering ranges (4.6 ° c). the july mean moult range temperature did not differ significantly from that in june on the summering ranges. we contend that failed or non-breeding pink-footed geese move eastward in svalbard to exploit the early stages of summer plant growth as a result of the delayed thaw compared with central and southern spitsbergen. keywords anser brachyrhynchus ; pink-footed geese; post-breeding; satellite tracking; svalbard; temperature gradients. moult migration in post-breeding waterfowl, first described by ekman (1922), is a well known event that takes place between the breeding season and the autumn migration. among goose species it mostly involves subadult birds, but may also include non-breeding and failed breeding birds, and even successful breeders (hohman et al. 1992). movements of palaearctic and nearctic goose species are in most cases northwards (salomonsen 1968; hohman et al. 1992). exceptions include barnacle geese ( branta leucopsis ) in greenland and probably to some extent greater snow geese ( anser caerulescens atlantica ), which move south within their breeding ranges (madsen et al. 1984; reed et al. 2003). the migration distance can vary from a few hundred kilometres to more than 1200 km in the case of pink-footed geese in iceland and greenland (madsen et al. 1984; boertmann 1994). there is much speculation as to why geese and other waterfowl undertake a moult migration. obviously there is an energy cost involved in the movement, but the benefits include access to abundant food resources, protection from predators and refuge from disturbance (hochbaum 1955; salomonsen 1968). food may be restricted on the breeding grounds, as suggested by madsen & mortensen (1987), and because breeders are often behaviourally dominant over non-breeders, there are benefits to the latter if they move to habitats outside the breeding range (salomonsen 1968; raveling 1970). in july, more northern habitats support the progressively delayed early correspondence christian m. glahder, national environmental research institute, university of aarhus, department of arctic environment, frederiksborgvej 399, box 358, dk-4000 roskilde, denmark. email: cmg@dmu.dk doi:10.1111/j.1751-8369.2007.00006.x 32 polar research 26 (2007) 31 – 36 © 2007 the authors eastward moult migration of non-breeding pink-footed geese c.m. glahder et al. growth phases of grass and sedge shoots, which have the highest protein content of the annual cycle at this time (whitten & cameron 1980; davis et al. 1985). hence, the forage quality in northerly areas with a growth season too short to support breeding birds may offer the springlike early season plant growth that is highly attractive to moulting geese. the greenland white-fronted goose ( anser albifrons flavirostris ) exhibits no marked moult migration, but may take advantage of the progressive development in availability of nutrient-rich food along an altitudinal gradient within the same general summering area (fox et al. 1983). in svalbard there is a west–east temperature gradient that mainly results from the influence of the “warm” north atlantic current on the west coasts of svalbard and the “cold” current from siberia on the eastern svalbard coastline. non-breeding pink-footed geese in svalbard moult within the breeding range (spitsbergen west of 17 ° e), and also in the eastern parts of svalbard mainly on the islands of edgeøya and barentsøya (madsen et al. 1992; mehlum 1998). according to mehlum (1998), less than 10% of the winter population (ca. 30 000 in the 1990s; madsen et al. 1999) were accounted for on edgeøya and barentsøya during the period of late july–september. this paper describes the movements and staging periods of individual pink-footed geese during the breeding and post-breeding period in svalbard based on data from birds fitted with small satellite transmitters. the geese were tracked from their possible breeding areas in june to their moulting grounds in july and their post-moulting areas prior to the onset of the autumn migration in midseptember. we test the hypothesis that moulting geese, freed from the association with nest sites and young, undertake a moult migration to areas where the delayed thaw offers spring-like feeding conditions away from breeding areas. we used satellite remote sensing to estimate surface temperatures of breeding and moulting areas to look for support for this hypothesis at larger spatial scales. food quality on the moulting grounds was inferred on the basis of the average monthly temperatures on spitsbergen, edgeøya and barentsøya. methods and study area satellite telemetry platform transmitting terminals (ptts; microwave telemetry inc., columbia, md, usa) were attached to 14 adult male pink-footed geese (seven in march 2003 and seven in march 2004), which had been cannon netted over bait at vest stadil fjord, denmark (56 ° 12 ′ n; 08 ° 08 ′ e; see glahder et al. in press for further details). six of these geese were tracked through to autumn migration. five of the ptts were 30-g battery powered units (for individual birds a2f, a4t, a4z and a5e in 2003 and b6k in 2004) and one was a 45-g solar powered unit (bird c1t in 2004). all the transmitters were mounted on the backs of the birds with glue. in addition, they were secured either with knicker elastic harnesses (glahder et al. 1997) or, in the case of the solar powered unit, with teflon straps (r. malecki, pers. comm.). the transmitters and harnesses constituted 1.3% (in the case of the 30-g ptts) and 1.7% (in the case of the 45-g ptt) of the body weights of the birds (average 2871 g, sd = 172 g, n = 14). the 30-g transmitters were programmed to transmit for 8 h and during three different periods to “rest” for 15 h (79 cycles, from about 1 april to 15 june), 159 h (11 cycles, from about 16 june to 31 august) or 111 h (until the battery power ran out). with a typical battery lifetime of 750 h estimated by microwave telemetry we expected our programmed ptts to transmit until at least late september of the same year. the solar powered ptt was programmed to transmit for 10 h and to “rest” for 21 h. details about the ptt transmissions, receptions, position calculations and accuracy are given in fox et al. (2003). positions were filtered using an argos filter v5.0 sas program developed by dave douglas (usgs, alaska science center, anchorage, ak, usa). with this program we excluded locations in the poorest quality classes ( < class 1) unless their locations were within 5 km of a previous or subsequent location. the areas, duration and timing of summering and staging for each staging area of a tracked bird, 50% dispersion ranges were calculated as harmonic means (with outliers removed and cell sizes optimized; dixon & chapman 1980) using range manager (1998 data solutions; a mapinfo professional application, http://solutionsgroup. tripod.com). the size of the dispersion range is a function of (1) the movements of the goose and (2) the position inaccuracy, i.e. the difference between the true location and the position derived from the calculated location. we defined a summering area as a potential breeding area. a staging area was described by at least eight valid positions, and if more than one staging area was used by the goose no overlap was accepted between 50% dispersion ranges. a moulting area was defined as a particular “staging” area if the tagged goose remained there for a minimum of 25 consecutive days (the average flightless period of nine goose species according to hohman et al. 1992), during most of july, when non-breeding pinkfooted geese are considered to be flightless (madsen et al. 1984). http://solutionsgroup c.m. glahder et al. eastward moult migration of non-breeding pink-footed geese polar research 26 (2007) 31 – 36 © 2007 the authors 33 minimum staging periods were calculated for each location by subtracting the time from the first position from that of the last position. because of the programmed “resting” periods of 21 h (solar powered transmitter) and 159 h (battery powered transmitters) during most of the post-breeding period, the actual staging period could be 42–318 h (about 2–14 days) longer than estimated. the summering and moulting areas were all located below 100 m a.s.l. (norwegian polar institute 1996), and all were near-shore areas, except for one summering area (river plain, a5e). most of the summering areas were in the cassiope tetragona and dryas octopetala zones of the mid arctic vegetation region defined by rønning (1996). habitats were tundra, except for one delta area. most of the moulting areas were in the papaver dahlianum zone of the high arctic vegetation region defined by rønning (1996). the moulting areas were either deltas or tundra with large lakes or lagoons. temperature data the moderate resolution imaging spectroradiometer (modis) is a remote-sensing instrument on board the terra (eos am) and aqua (eos pm) satellites, providing a range of environmental data at three spatial scales: 250, 500 and 1000 m (friedl et al. 2002; petitcollin & vermote 2002). for the present study, the mod11 product within the larger modis dataset was used to generate information on mean monthly land surface temperatures ( ± 0.5 ° c) across the entire svalbard area (usgs eros data center 2002). these data were imported into arcgis version 9.0 and converted to raster format at a 1-km resolution. for each goose staging area, defined by a 50% dispersion range, average monthly temperatures were calculated for june and july. to calculate differences in mean temperatures between summering sites (areas in western spitsbergen) and moulting sites (areas mainly in eastern svalbard), we averaged the mean temperatures on each type of site for five of the geese. the goose b6k was omitted because it moulted at the summering site (table 1). the two averages that had similar variances ( f -test, two-tailed) were tested with a two-tailed student’s t -test. results movements and staging areas upon arrival to svalbard in late may, the geese fitted with satellite transmitters moved to summering sites in central, western or northern parts of spitsbergen (glahder et al. in press). five of the six geese left these areas between 11 and 30 june, while the sixth goose (b6k) stayed on the island of prins karls forland until 5 september (fig. 1; table 1). all five geese went east and four geese staged at eastern localities until the autumn migration. the average arrival date at the eastern sites was 28 june (sd = 11 days, range = 16 june–13 july). birds used either one or no staging areas before the moult (fig. 1). one of the five geese (a5e) stayed on edgeøya from 16 to 22 june and then proceeded to northern spitsbergen, where it stayed during the moulting period. the last signal from a5e was received from northern spitsbergen on 9 september (fig. 1). on average, the five geese moved 180.0 km (great circle route, sd = 21.4 km, n = 5) from summering to moulting areas; the direction was east with an average summering position of 78.1 ° n, 15.7 ° e (sd n = 0.6 ° , sd e = 1.6 ° , n = 5) and an average moulting position of 78.3 ° n, 21.0 ° e (sd n = 1.1 ° , sd e = 2.5 ° , n = 5). the five geese stayed at a moulting area for an average of 47.2 days (sd = 17.8 days, n = 5) (table 1), and after that period they moved between an average of 1.4 staging table 1 summering and moulting sites for satellite-tagged pink-footed geese. mean june and july temperatures are shown for the two sets of areas. the number of 1-km squares (pixels) inside each 50% dispersion range is given for each of the two types of sites. the summering and moulting periods are minimum periods as defined in the text, and dates are given in day and month (e.g., 27/5 is 27 may). the migration distance is the great circle route in kilometres from west (w) to east (e) between the two areas. goose id dist. w–e (km) summering site dates no. pixels position ° n, ° e mean june temp. ( ° c) mean july temp. ( ° c) moulting site dates no. pixels position ° n, ° e mean june temp. ( ° c) mean july temp. ( ° c) a2f 215 27/5–11/6 98 78.7, 15.3 − 1.06 11.13 02/7–30/7 55 77.5, 22.8 − 0.23 4.68 a4t 180 23/5–30/6 22 78.2, 13.5 3.70 9.55 13/7–17/8 33 78.9, 20.9 − 4.70 2.16 a4z 162 08/6–15/6 11 78.2, 17.0 10.0 14.54 28/6–08/8 25 77.5, 22.8 2.40 9.72 a5e 180 21/5–14/6 22 78.2, 17.4 8.28 10.59 24/6–25/8 42 79.9, 16.8 − 1.41 6.50 c1t 163 23/5–29/6 14 77.0, 15.4 1.94 8.70 03/7–11/9 48 77.5, 21.7 − 0.36 4.51 b6k 251 01/6–05/9 a 11 78.5, 11.0 3.58 11.03 10.9 b 142 c 78.2, 22.1 1.96 5.05 a the goose moulted in the summering area, and b stayed only briefly on northern edgeøya before the autumn migration. c the autumn range of b6k was poorly defined by data from one day only (six positions). 34 polar research 26 (2007) 31 – 36 © 2007 the authors eastward moult migration of non-breeding pink-footed geese c.m. glahder et al. areas (range 0–3) before they started their autumn migration. the average departure date from the moulting areas was 18 august (sd = 16.5 days, n = 5; table 1). b6k went east to stage on edgeøya for between 1 (minimum) and 9 (maximum) days before its autumn migration. b6k was observed on wintering grounds in the netherlands; the individual was associated with a female goose but without any juveniles (f. cottaar, pers. comm.). the date of the last signal transmitted from the geese in svalbard before the onset of the autumn migration was 11 september (sd = 2.2 days, n = 6, variation: 9–15 september). the dataset comprised in total 1362 positions (average = 227, sd = 161, n = 6, variation: 107–507). mean temperatures at staging areas the differences in mean temperatures between western spitsbergen (summering sites) and eastern svalbard (moulting sites on edgeøya and barentsøya and in eastern and northern spitsbergen) were illustrated by calculating mean temperatures at 50% dispersion ranges during june and july (table 1; figs 2, 3). in june, the mean temperature in the western areas was 4.6 ° c (sd = 4.5 ° c, n = 5) and –0.9 ° c (sd = 2.6 ° c, n = 5) in the eastern areas—a significant difference of 5.4 ° c (student’s t -test, p = 0.05, t = 2.39, df = 8). in july, the mean temperature in the western areas was 10.9 ° c (sd = 2.2 ° c, n = 5) and 5.5 ° c (sd = 2.8°c, n = 5) in the eastern areas, a significant difference of 5.4°c (student’s t-test, p = 0.01, t = 3.39, df = 8). the difference of 0.9°c (5.4–4.6°c) between mean july temperatures in the eastern areas and mean june temperatures in the western areas was not significantly different (student’s t-test, p > 0.1, t = 0.38, df = 8). discussion to our knowledge, this paper is the first to document an eastward moult migration in northern hemisphere goose populations. pink-footed geese arriving in svalbard in late may need good foraging conditions to replenish body reserves lost during the ca. 1100 km migration—much of it over the open sea—prior to the initiation of egg-laying. in our study, pink-footed geese arriving in svalbard in mid-may encountered air temperatures below 0°c, and were therefore almost entirely restricted to feeding on above-ground grass litter from the previous year (fox et al. in press). following initial staging for about one week, the geese moved to summering sites in western spitsbergen (glahder et al. in press). the areas used by pink-footed geese fitted with ptts had mean june temperatures of 4–5°c. temperatures above 0°c spur the growth of fresh shoots of tundra plants, and the thawing ground gives the geese access to below-ground plant storage organs. figure 1 movements and staging areas of transmitter-tagged pinkfooted geese in svalbard during the period of june–september in 2003 and 2004. dispersion ranges (50%) and movements are shown for six individual geese: (a) a2f, a4t and b6k; and (b) a4z, a5e and c1t (identification numbers indicated at summering sites). arrows pointing at filled-in dispersion ranges indicate moulting sites. b6k probably moulted on the summering site and it staged only briefly at the post-moulting site on edgeøya before the autumn migration. (a) (b) c.m. glahder et al. eastward moult migration of non-breeding pink-footed geese polar research 26 (2007) 31 – 36 © 2007 the authors 35 during the second part of june, five of the six pinkfooted geese tagged with ptts moved about 200 km eastwards, while the sixth goose stayed at the summering site until shortly before the autumn migration. as the pinkfooted goose moults remiges during most of july (madsen et al. 1984) and the five geese moved out of their summering sites prior to that period, we interpret this movement as a moult migration of either failed or nonbreeding geese. this interpretation is supported by the fact that the average staging period lasted more than 25 days and covered most of july. the mean july temperature in the moulting areas increased from below the freezing point in june to 5.5°c in july. this means that the geese are likely to have encountered soil conditions and plant growth stages (and hence forage conditions) similar to those experienced at the western summering sites in june. with the relatively modest energy expenditure of a 200-km flight, the geese regained access to optimal forage conditions with fresh new growth of grasses and sedges. they also gained access to belowground storage organs, although these may not be of main importance in the diet if the feeding behaviour during their moult is similar to that of pink-footed geese in iceland and greenland (madsen & mortensen 1987). the geese moved out of their moulting areas around mid-august to stage at relatively few other areas in svalbard before the autumn migration. this suggests that exploitation of moulting areas extends through the greater part of the pre-migration fattening period, when energy demands are high. because the plant growing season begins too late to sustain breeding attempts in these areas, another advantage of using eastern moulting sites is that the moulters meet comparatively little intraspecific competition from breeding geese here. figure 2 mean june temperatures (°c) on svalbard in 1-km squares. temperatures are given in 2°c intervals except for temperatures below 0°c and above 18°c, each of which are pooled in one category. the dispersion ranges (50%) (disp. range) covering summering and moulting sites are shown for the six geese attached with platform transmitting terminals (ptts) (see fig. 1). figure 3 mean july temperatures (°c) on svalbard in 1-km squares. temperatures are given in 2°c intervals except for temperatures below 0°c and above 18°c, each of which are pooled in one category. the dispersion ranges (50%) (disp. range) covering summering and moulting sites are shown for the six geese attached with platform transmitting terminals (ptts) (see fig. 1). 36 polar research 26 (2007) 31 – 36 © 2007 the authors eastward moult migration of non-breeding pink-footed geese c.m. glahder et al. interspecific competition from barnacle geese and brent geese (branta bernicla) is unlikely because these species are scarce in this part of svalbard (madsen et al. 1992; mehlum 1998). the moulting grounds on edgeøya and barentsøya (fig. 1) have relatively high densities of svalbard reindeer (rangifer tarandus platyrhynchus) (kovacs & lydersen 2006), on which the arctic fox (alopex lagopus) is highly dependant all year round (eide 2002). on the other hand, densities of breeding birds are low in these areas so the predation pressure from the foxes is probably relatively low. acknowledgements we would like to thank peter aastrup, national environmental research institute, for his help with transforming the satellite data into the gis platform for analysis. j.-f. giroux and an anonymous referee are thanked for their valuable comments on the first version of the paper. the study was performed under the eu 5th framework project fragile (evk2-2001-00235). references boertmann d.m. 1994. an annotated checklist to the birds of greenland. meddelelser om grønland, bioscience 38. davis r.a., jones r.n., macinnes c.d. & pakulak a.j. 1985. molt migration of large canada geese on the west coast of hudson bay. wilson bulletin 97, 296–305. dixon k.r. & chapman j.a. 1980. harmonic mean measure of animal activity areas. ecology 61, 1040–1044. eide n.e. 2002. spatial ecology of arctic foxes. relations to resource distribution, and spatiotemporal dynamics in prey abundance. phd thesis, dept. of biology and nature conservation, agricultural university of norway/norwegian polar institute. ekman s. 1922. djurvärldens utbredningshistoria på skandinaviska halvön. (the distribution history of animals on the scandinavian peninsula.) stockholm: bonniers. fox a.d., francis i.s. & bergersen e. in press. diet and habitat use of svalbard pink-footed geese during arrival and prebreeding periods in adventdalen. ardea 94. fox a.d., glahder c.m. & walsh a.j. 2003. spring migration routes and timing of greenland white-fronted geese— results from satellite telemetry. oikos 103, 415–425. fox a.d., madsen j. & stroud d.a. 1983. a review of the summer ecology of the greenland white-fronted goose anser albifrons flavirostris. dansk ornitologisk forenings tidsskrift 77, 43–55. friedl m.a., mciver d.k., hodges j.c.f., zhang x.y., muchoney d., strahler a.h., woodcock c.e., gopal s., schneider a., cooper a., baccini a., gao f. & schaaf c. 2002. global land cover mapping from modis: algorithms and early results. remote sensing of environment 83, 287–302. glahder c., fox a.d. & walsh a.j. 1997. effects of fitting dummy satellite transmitters to geese. wildfowl 48, 88–97. glahder c.m., fox a.d., hübner c.e., madsen j. & tombre i.h. in press. pre-nesting site use of satellite transmitter tagged svalbard pink-footed geese. ardea 94. hochbaum h.a. 1955. travels and traditions of waterfowl. minneapolis, university of minnesota press. hohman w.l., ankney c.d. & gordon d.h. 1992. ecology and management of postbreeding waterfowl. in b.d.j. batt et al. (eds.): ecology and management of breeding waterfowl. pp. 128– 189. minneapolis: university of minnesota press. kovacs k.m. & lydersen c. (eds.) 2006. birds and mammals of svalbard. polarhåndbok 13. tromsø: norwegian polar institute. madsen j., bregnballe t. & hastrup a. 1992. impact of the arctic fox alopex lagopus on nesting success of geese in southwest svalbard, 1989. polar research 11, 35–39. madsen j., kuijken e., meire p., cottar f., haitjema t., nicolaisen p.i., bones t. & mehlum f. 1999. pink-footed goose anser brachyrhynchus: svalbard. in j. madsen et al. (eds.): goose populations of the western palearctic. a review of status and distribution. wetlands international publication 48. pp. 82–93. rønde, denmark: national environmental research institute. madsen j. & mortensen c.e. 1987. habitat exploitation and interspecific competition of moulting geese in east greenland. ibis 129, 25–44. madsen j., mortensen c.e. & boertmann d. 1984. the significance of jameson land, east greenland as moulting and breeding area for geese: results of censuses 1982–84. dansk ornitologisk forenings tidsskrift 78, 121–131. mehlum f. 1998. areas in svalbard important for geese during the pre-breeding, breeding and post-breeding periods. in f. mehlum et al. (eds.): research on arctic geese. proceedings of the svalbard goose symposium, oslo, norway, 23–26 september 1997. norsk polarinstitutt skrifter 200. pp. 41–55. oslo: norwegian polar institute. norwegian polar institute 1996. svalbard 1:250,000. topographic maps 1 and 2. oslo: norwegian polar institute. petitcollin f. & vermote e.f. 2002. land surface reflectance, emisivity and temperature from modis middle and thermal infrared data. remote sensing of environment 83, 112–134. raveling d.g. 1970. dominance and agonistic behaviour of canada geese in winter. behaviour 37, 291–319. reed e.t., bêty j., mainguy j., gauthier g. & giroux j.-f. 2003. molt migration in relation to breeding success in greater snow geese. arctic 56, 76–81. rønning o.i. 1996. svalbards flora. (the flora of svalbard.) polarhåndbok 9. oslo: norwegian polar institute. salomonsen f. 1968. the moult migration. wildfowl 19, 5– 24. usgs eros data center 2002. modis reprojection tool user’s manual. dept. of mathematics and computer science, south dakota school of mines and technology. whitten k.r. & cameron r.d. 1980. nutrient dynamics of caribou forage on alaska’s arctic slope. in e. reimers et al. (eds.): proceedings of the second international reindeer/caribou symposium. pp. 159–166. trondheim: direktoratet for vilt og ferskvannsfisk (directorate for fish and game). zeeberg.indd 385zeeberg et al. 2003: polar research 22(2), 385–394 climate variability in the eurasian arctic is signifi cantly modulated by north atlantic oceanic heat fl ux. weather stations on novaya zemlya since 1961 document summer temperatures 0.3 0.5 °c and winter temperatures 2.3 2.8 °c lower than in the fi rst half of the 20th century (zeeberg & forman 2001). this temperature decrease is associated with a prolonged negative phase of the north atlantic oscillation (nao), decreased advection of north atlantic water, and below-average southern barents sea sea surface temperature (sst) during the 1960s, ‘70s and ‘80s (loeng 1991; zeeberg & forman 2001). likewise, post-”little ice age” warming of the barents sea and glacier retreat on northern novaya zemlya is associated with a persistent positive phase of the nao. meteorological observations at the polar station russkaya gavan’, north-west novaya zemlya (76° 11' n, 59° e, fig. 1), between 1932 and 1995 are concurrent with a mass balance time series on the adjacent shokal’ski glacier from 1933 to 1969. stabilization and advance of several tidewater glaciers at novaya zemlya in the second half of the 20th century refl ects decreased summer temperatures and/or increased precipitation (koryakin 1986; zeeberg & forman 2001). elevated winter precipitation (up to 20 mm above the 27 mm average) associated with increased cyclonic activity, together with slowing calving rates, arrested the negative mass balance of the shokal’ski glacier between 1959 and 1966. observations during the 20th century indicate, however, that continued regional warming and summer temperature anomalies less than < 1 °c compensate for the added precipitation, resulting in negative mass balances and glacier retreat (chizov et al. 1968; zeeberg & forman 2001). here we evaluate fjord sediment records as proxy for decadeto century-scale fl uctuations of a tidewater glacier on north-west novaya zemlya. this analysis is based on the inference that glacier extent in a novaya zemlya fjord during the “little ice age” inferred from glaciomarine sediment records jaapjan zeeberg, steven l. forman & leonid polyak glacier activity at russkaya gavan’, north-west novaya zemlya (arctic russia), is reconstructed by particle size analysis of three fjord sediment cores in combination with 14c and 210pb dating. down-core logging of particle size variation reveals at least two intervals with sediment coarsening during the past eight centuries. by comparing them with reconstructions of summer temperature and atmospheric circulation, these intervals are interpreted to represent two cycles of glacier advance and retreat sometime during ca. ad 1400–1700 and ad 1700–present. sediment accumulation thus appears to be sensitive to century-scale fl uctuations of the barents sea climate. the identifi cation of two glacier cycles in the glaciomarine record from russkaya gavan’ demonstrates that during the “little ice age” major glacier fl uctuations on novaya zemlya occurred in broad synchrony with those in other areas around the barents sea. j. j. zeeberg, netherlands institute for fisheries research, haringkade 1, box 68, 1970 ab ijmuiden, the netherlands, jzeebe1@uicalumni.org; s. l. forman, dept. of earth and environmental sciences, university of illinois at chicago, 845 w. taylor street, chicago, il 60607-7059, usa; l. polyak, byrd polar research center, ohio state university, 1090 carmack rd., 108 scott hall, columbus, oh 43210-1002, usa. 386 glacier extent in a novaya zemlya fjord during the “little ice age” the glacial-marine record predominantly refl ects meteorological and glacier-specifi c mod ulations of sediment input (see elverhøi et al. 1983; smith & schafer 1987; syvitski et al. 1987; cowan et al. 1988; gilbert 2000). to assess changes in sedimentation, particle size variation was measured for three 1.2 m long gravity cores from russkaya gavan’, a > 100 m deep, 10 km long fjord, dominated by the shokal’ski glacier (fig. 1). cores were retrieved at ca. 1 km (ip98-22), ca. 3.3 km (ip98-23) and ca. 3.8 km (ip98-24) from the present glacier terminus (figs. 1, 2). a second glacier (laktyonov glacier), which does not terminate in the fjord, may also contribute to fjord sedimentation through meltwater streams. sediment accumulation in russkaya gavan’ may record glacier response to climate change during the “little ice age” and other neoglacial events that have been widely recognized in the barents sea region and scandinavia (e.g. matthews 1991; fig. 1. russkaya gavan’ with shokal’ski and laktyonov glaciers. the positions of cores ip98-22, 23 and 24 and the position of core asv-987 (indicated by a star) are shown. the long dashed line shows the inferred maximum glacier extent in the past 600 years. a shell obtained from the end moraine that indicates the “little ice age” grounding line (short dashed line) of the shokal’ski glacier was dated to ad 1300–1400. inset: pathways of north atlantic water along the barents shelf and across the barents sea. the black block on novaya zemlya indicates the location of russkaya gavan’. 387zeeberg et al. 2003: polar research 22(2), 385–394 werner 1993; lubinski et al. 1999). methods core collection at russkaya gavan’ geological sampling and oceanographic measurements were performed in september 1998 from the rv ivan petrov. the glacial marine succession sampled by the ip-98 gravity cores is indicated by an 8.8 khz sonar profi le of the sea fl oor (fig. 2). a thin (< 10 m) sedimentary cover (refl ector c) drapes the surface of another refl ector (a, b), probably a glacigenic diamicton. thicker sedimentary sequences (ca. 30 m) can be seen in topographic depressions. at the location of one of the cores, ip98-23, an hermetically sealed box core was obtained to assure collection of the sediment–water interface needed for 210pb dating. a 6 m long gravity core (asv-987) obtained and sampled in 1997 provides additional information on depositional variability within the fjord (polyak et al. in press). observations of water turbidity and conductivity, temperature and depth (ctd) measurements in russkaya gavan’ in conjunction with the 1998 cruise indicate that meltwater is discharged from subglacial or englacial channels at the fjord head. the density difference between seawater and freshwater is 24 28 kg/m3, causing rapid rise of the freshwater plume and settling of coarse-grained sediments in the resulting zone of deceleration, while fi ne fractions are dispersed throughout the fjord (elverhøi et al. 1983; syvitski et al. 1987; gilbert 2000). a light transmissivity profi le and sampling of suspended matter demonstrates turbid layers along the sea surface and bottom of russkaya gavan’ (fig. 2). suspended sediment loads decrease ca. 2 km beyond cores 23, 24 and asv-987. the spatial extent and coarseness of the plume principally refl ects glacier position, meltwater production, and fjord hydrodynamics (syvitski et al. 1987: 111–174). lithology cores ip98-22, 23, and 24 consist of homogeneous silty-mud with centimetreto millimetre-scale lamination and incidental clasts of icerafted debris (ird; fig. 3). oxidation of organic carbon was indicated after core splitting by release of h2s and black colouration. beds with diffuse lamination 10 20 cm thick alternate with beds that have fi ne lamination highlighted by reduced (black) monosulphides. monosulphide beddings are most pronounced in ip98-23, suggesting periodic increase of clastic deposition alternating with settling of organic matter. the lower half of core 22 is more compact than the upper half and has two noticeable sandy layers. down-core fl uctuations of grain size were established with a malvern particle size analyser (mastersizer 2000, hydro2000 mu), which measures grain diameters by laser diffraction while a subsample in liquid suspension is pumped through a recirculating cell. cores 23 and 24 were sampled at 1 cm intervals, and core 22 at 2 cm intervals because of expected increase of accumulation rates with proximfig. 2. sonar (8.8 khz) profi le of russkaya gavan’, showing turbid layers measured in the fjord and the locations of the ip98 and asv-987 gravity cores. the acoustic profi le demonstrates that a thin (< 10 m) sedimentary cover (refl ector c) is draping another refl ector (a, b) along the fjord, with accumulation up to 30 m thick in topographic depressions. refl ector (a, b) is probably a glacigenic diamicton. 388 glacier extent in a novaya zemlya fjord during the “little ice age” (a) (b) 389zeeberg et al. 2003: polar research 22(2), 385–394 ity to the glacier. marine carbonates and organics were removed during sample preparation by adding hcl (10 %) and h2o2 (30 %), respectively. when reactions ceased, the mixture was diluted with distilled water before addition of a dispersant (ca. 0.3 g na4p2o7.10h2o). a subsample was then taken with a pipette while stirring and released in the sample tank of the mastersizer. to separate remaining particle agglomerations, ultrasonics were applied for 10 s. instrument settings were held constant with laser obscuration at approximately 15 % and a pump speed of 2500 rpm. each sample yielded an apparent gaussian distribution of particle sizes. plotted in fig. 3 are particle size ranges as volumetric percentages of the total sample and the particle size of the 90th percentile (d90). the d90 shows fl uctuation of the coarse tail of the distribution (fig. 5), registering particle size fl uctuations more sensitively than, for example, the median (d50). fine silt and clay (wentworth scale: fractions < 16 µm) predominate in each core, comprising 80 90 % of core 24 (the most distal core), and 70 90 % in cores 22 and 23 (fig. 3). median particle size is 7.6 µm for core 22, 7.1 µm for core 23 and 6.7 µm for core 24, refl ecting a decrease of coarse fractions away from the glacier. this trend is also observed in other studies of glaciomarine sediments (e.g. gilbert 2000; desloges et al. 2002). the particle size analysis demonstrates that coarse silt and sand (fractions 63 125 µm and > 125 µm) comprise up to 12 % of core 22, compared to < 6 % in core 23 and < 2 % in core 24. in cores 23 and 24 fi nely laminated beds are somewhat (respectively 10 and 2 %) enriched in coarse sediments (medium to coarse silt and fi ne sand). ird occurs throughout each core as incidental, < 10 mm long angular to subangular rock fragments. ird is notably abundant in the lower half of core 24. the largest ird fragments are 20 mm in core 23 (depth 12 cm) and core 24 (depth 61 cm). fig. 3. plots of grain size percentages with depth for cores (a, opposite page) ip98-22, (b, opposite page) 23, and (c) 24. from left to right are shown contents of sand, silt, and clay grouped in ranges (wentworth scale): 1) coarser than fi ne sand, 2) coarse silt and fi ne sand, 3) medium to coarse silt, 4) fi ne silt and clay. core photographs were taken immediately after core splitting to preserve black colouration of layering caused by reduced monosulphides. the core “shadows” in this fi gure (images to the right of the photographs) are composite x-radiographs used to identify molluscs and ird. (c) 390 glacier extent in a novaya zemlya fjord during the “little ice age” results chronology: 14c and 210pb dating radiocarbon dating of in situ molluscs from the top and base of the cores provides broad chronological control (figs. 3, 4, table 1), with calibrated age ranges spanning 300 to 500 years (stuiver et al. 1998). an additional challenge for 14c dating is the large and variable local marine reservoir correction. a study of bivalves from novaya zemlya fjords indicates a reservoir correction of 775 ± 200 yr for portlandia arctica, a detrital-feeding bivalve that can burrow up to 20 cm into sediments and feeds on old organic matter within (forman & polyak 1997). this mollusc has a broad salinity tolerance and may live close to glaciers. hence, the large reservoir correction indicated by this shell may result from assimilation of old carbon from glacier meltwater and/or detrital organics from sediments. suspension feeding bivalves (e.g. astarte sp., macoma sp.) are also common in glaciomarine sediments from russkaya gavan’, and previously yielded a reservoir age of ca. 400 ± 100 yr (forman & polyak 1997; see also heier-nielsen et al. 1995). excess 210pb activity measurements on unconsolidated near-surface sediments provide a more precise age model for the past century than 14c (e.g. smith & schafer 1987; hughen et al. 2000). linear regression of 210pb on depth in a 30 cm sealed core retrieved with ip98-23 gives a sedimentation rate of 8 mm/yr, assuming a 226ra background of 1.5 dpm/g (fig. 4). 210pb dating is often calibrated by location of the 137cs “bomb” spike. the 137cs fallout peak was ca. 1964, but there is often a delay of 5 to 10 years before cesium settles from the water column with sediments. analysis of the reference core did not yield the cesium spike, which may be due to sediment mixing or low isotope concentration, because deposition from the atmosphere decreases above ca. 60° n (hughen et al. 2000; j. smith, pers. comm. 2001). the sedimentation rate derived by 210pb analysis demonstrates that the reference core covers the 1970s. the 137cs isotope slightly increases downcore, consistent with elevated ambient 137cs during this period (fig. 4). in contrast to the 210pb-derived decadal rate, 14c dating of consolidated sediments provides a maximum limiting chronology because of the effect of time averaging, potentially yielding sedimentation rates that are too low. basal ages of at least 600 years were derived by 14c dating of macoma sp. bivalves for cores ip9823 (1.12 m) and ip98-24 (1.24 m). the resulting linear sedimentation rate of ca. 2 mm/yr is comparable to rates calculated for subpolar fjords of north spitsbergen (elverhøi et al. 1983) and west greenland (desloges et al. 2002). comparison with core asv-987, which has a mean accumulation rate of ca. 6 mm/yr (polyak et al. in press) indicates substantial variability of sediment distribution within the fjord. higher accumulation fig. 4. (a) age model for the ip98 and asv-987 cores based on calibrated 14c ages obtained from molluscs. (b) modern sedimentation rates in russkaya gavan’ are derived from analysis of the 210pb decay series in a 0.3 m core that collected the sediment–water interface (including modern 210pb) at the location of ip98-23. the 137cs isotope increases down-core, consistent with elevated 137cs levels during the 1960s and 1970s. (a) (b) 391zeeberg et al. 2003: polar research 22(2), 385–394 rates in asv-987 shows that thicker sediment was sampled here, possibly refl ecting additional sedimentation from the laktyonov glacier’s fl uvial delta (fig. 1). a mollusc at 56 cm in core ip98-22 yielded a submodern age, indicating a higher accumulation rate (ca. 5 10 mm/yr) for core 22 than for cores 23 24, consistent with its glacier proximal position. with accumulation rates 5 (14c) to 8 (210pb) mm/yr, core 22 is probably continuous through the 19th century. there is no 14c age control for the past three centuries for ip98-23 and 24. crosscorrelation between cores based on shell ages and peaks in the coarse fraction suggests that of ip9823 and 24 the core tops, comprising the past ca. 50 100 years, were lost during coring (fig. 5). glacier proximity in the sedimentary record the sediment record in russkaya gavan’ is dominated during the past ca. 800 years by fi negrained glacifl uvial deposition with some input from ird and sediment gravity fl ows. the exclusively clay to medium silt-sized particle ranges measured in cores 22 24 suggest that these cores were retrieved from glacier-distal environments, dominated by settling of silt and agglomerated clay particles from suspension. coarse silts and sands (63 125 and > 125 µm, fig. 3) constitute < 2 % in core 24 (3.8 km from the glacier), < 6 % in core 23 (3.3 km from the glacier), and < 12 % in core 22 (1 km away from the glacier). medium-grained sand is deposited within ca. 200 m from ice fronts in fjords of north-west spitsbergen (elverhøi et al. 1993). turbulent, high energy meltwater discharge by temperate, high precipitation glaciers of south-east alaska deposits sand within 1 km of the glacier terminus (cowan et al. 1988). hence, for the subpolar shokal’ski glacier we infer that the absence of medium sands (250 µm) in ip98-22, obtained ca. 1 km from the present glacier terminus, suggests that this core was > 0.2 km from the grounding line at all times (fig. 1). the increase in fractions > 125 µm between 40 and 80 cm indicates increased meltwater discharge and/or increased glacier proximity in the mid-19th century (figs. 3, 5). limited glacier advance (< 1 km) is consistent with an apparent absence of “little ice fig. 5. correlation of ip cores based on calibrated 14c age ranges. shown here is the fl uctuation with depth of the grain diameter of the 90th percentile (d90, see text for explanation). 392 glacier extent in a novaya zemlya fjord during the “little ice age” age” moraines on the acoustic profi le. possible moraine ridges (see elverhøi et al. 1983) ca. 3 km down the fjord were probably produced by an earlier grounding line (fig. 2). historical observations (jermolaev 1934 cited in chizov et al. 1968; also zeeberg & forman 2001) indicate that during the 19th century, the fl oating (calving) glacier margin extended further than the grounding line and over the location of ip98-22. the glacier’s limited response to climate fl uctuations in the past ca. 800 years may refl ect its steep areaelevation gradient (fig. 1), making it less susceptible to changes in equilibrium line altitude (zeeberg & forman 2001). discussion interpretation of the grain size signal suspended sediment loads in subpolar, glacierdominated fjords commonly range between 50 and 200 mg/l during summer, but in winter these loads are usually < 2 mg/l (syvitski et al. 1987: 123, 134). during winter, glacier melt and output of sediment with meltwater is minimal. climate change primarily affects the length of the summer (melt) season, which for russkaya gavan’, at sea level, has been less than two months (july and august) during the exceptionally warm 20th century (> 1 °c anomaly; briffa et al. 1995). the net annual mass balance may be determined during these summer months by a few melt days, and thus by cloudiness and sea ice, which limits heat transport to the region. cold periods can be characterized by a low number of “melt years”, reduced meltwater delivery, and low net sediment accumulation. increased melt would result in increased sediment output and an increase of coarse fractions. the 14c-constrained glaciomarine record from russkaya gavan’ reveals two intervals with signifi cant sediment coarsening and a concomitant drop of fi ne fractions (fig. 3). correlation of the cores based on 14c ages reveals that these coarsening episodes were probably produced by the same cycles of glacier advance–stabilization– retreat (fig. 5). because the core sites characterize different sedimentation zones in the fjord, the expression of coarsening varies between cores. thus, a narrow peak in core 23 (40 cm, coarse fraction 6 %) appears to correlate with a broader peak in core 24 (35 cm, coarse fraction 2 %). the age of the lower coarsening event can be broadly estimated as between the 14th and 17th century, whereas the upper coarse interval may be about two centuries younger based on sedimentation rates of 2+ mm/yr. the younger coarsening event may be correlative to the coarse part of core 22, although age control of this core is insuffi cient for a defi nitive correlation. table 1. pelecypod species and ages for the ip98 cores. depth (cm) species andres. correction 14c age (yr bp) (lab. number) res. corr. 14c age cal age (yr ad ) 1σ (2σ) and probability midpoint plotted (1σ) core ip98-22 56 portlandia biv 290 ± 40 modern modern 1950 core ip98-23 55 portlandia biv. 400 ± 100 1025 ± 45 (aa-37278) 625 ± 145 1270–1434 (1066–1625) 1243–1442 (0.997) 775 ± 200 250 ± 245 1428–mod (1280–mod) 1478–1698 (0.573) 1588 106 macoma biv. 1225 ± 55 (aa-37279) 825 ± 155 1024–1297 (895–1419) 1147–1291 (0.610) 1160 core ip98-24 102 portlandia? fragments 775 ± 200 1205 ± 45 (aa-37281) 805 ± 145 1037–1376 (977–1419) 1150–1298 (0.663) 430 ± 245 1297–1945 (1060–mod) 1293–1675 (0.946) 1484 110 macoma biv. 400 ± 100 925 ± 55 (aa-37280) 525 ± 155 1296–1486 (1216–1786) 1288–1517 (0.937) 1402 393zeeberg et al. 2003: polar research 22(2), 385–394 inferred glacial history glaciers on novaya zemlya during the 20th century demonstrate variable response to regional warming, because increased barents sea sst enhance both summer ice melt and winter precipitation (zeeberg & forman 2001). however, prolonged warming and summer temperature anomalies > 0.5 °c result in a declining shokal’ski glacier mass balance (chizov et al. 1968; mikhalov & chizov 1970). summer temperature anomalies are well documented by tree-ring derived temperature time series for northern russia (briffa et al. 1995) and temperature composites (including ice cores) for the northern hemisphere (mann et al. 1999). strongly negative summer temperature anomalies may herald the advance of glaciers on novaya zemlya in the early 14th century (and also in the 19th century). this is consistent with the dating of an astarte bivalve from a subfossil moraine ridge at a distance of ca. 500 m from shokal’ski glacier’s present terminus to ad 1300–1400 (zeeberg 2001). the abundance of ird in the bottom half of core 24 may indicate stabilization of the advanced glacier with iceberg calving at some time between ca. ad 1300 and 1700. glacier melt that would have ended this cycle was probably caused by increased advection of north atlantic water into the barents sea during a persistent positive phase of the nao. between ad 1450 and 1650 there were at least four episodes with persistent positive phase naos (cook et al. 2002). a drop of north atlantic sea level pressure is indicated by ion contents in the gisp-2 ice core after ad 1400 (meeker & mayewski 2002). after ca. ad 1650 the nao remains comparatively weak until the 20th century. strong negative summer temperature anomalies (briffa et al. 1995; mann et al. 1999) in combination with increased precipitation, as suggested by strengthening of the icelandic low (meeker & mayewski 2002), probably caused signifi cant glacier advance on novaya zemlya in the 19th century. we suggest that the second glacier cycle inferred from the glaciomarine sequence from russkaya gavan’ corresponds to the 19th century glacier maximum and subsequent decay. the coarse layers in the bottom half of core 22 may indicate turbidity currents triggered by the advancing glacier (figs. 3, 5). the sediment cores from russkaya gavan suggest two “little ice age” glacier advances sometime during ca. ad 1300–1700 and ad 1700–present (fig. 5). these events appear to be generally consistent with glacial geologic observations from other areas around the barents sea. glacier advances in franz josef land are constrained by 14c dating of in situ mosses from glacier margins to ca. ad 1400–1600 and post-1650 (lubinski et al. 1999). two stages of moraine stabilization, in the 14th century and post-1700, have been described for svalbard on the basis of lichenometry (werner 1993). in southern scandinavia, “little ice age” maxima were reached between ad 1400 and ad 1600 (matthews 1991). glaciers on svalbard, franz josef land, and novaya zemlya attained their greatest “little ice age” extent in the second half of the 19th century (werner 1993; lubinski et al. 1999; zeeberg & forman 2001). the identifi cation of two glacier cycles in the glaciomarine record demonstrates that sediment accumulation in russkaya gavan’ is sensitive to century scale fl uctuations of the barents sea climate. during the “little ice age”, major glacier fl uctuations on novaya zemlya appear to have occurred in broad synchrony with those in other areas around the barents sea. acknowledgements.—210pb and 137cs analyses were performed by john n. smith, bedford institute of oceanography (dartmouth, canada). particle size analyses were done in cooperation with torbjörn törnqvist (university of illinois at chicago). sonar profi le is reproduced courtesy of p. i. krinitski, v. a. gladysh, and y. p. goremykin (okeangeologia, st. petersburg, russia). lawrence febo produced the x-ray images and jeanne jaros (both of the byrd polar research center) the core photographs. this paper benefi ted from reviews by j. a. matthews and an anonymous referee. national science foundation award no. opp-9796024 supported the research. references briffa, k. r., jones, p. d., schweingruber, f. h., shiyatov, s. g., & cook, e. r. 1995: unusual twentieth-century summer warmth in a 1,000-year temperature record from siberia. nature 376, 156–159. chizov, o. p., koryakin, v. s., davidovich, n. v., kanevsky, z. m., singer, e. m., bazheva, v. y., bazhev, a. b. & khmelevskoy, i. f. 1968: results of researches on the program of the international geophysical year. glaciation of the novaya zemlya. glaciology ix section of igy program. no. 18. (in russian, with english summary.) moscow: nauka publishing house. cook, e. r., d’arrigo, r. d. & mann, m. e. 2002. a well verifi ed, multiproxy reconstruction of the winter north atlantic oscillation index since ad 1400. j. clim. 15, 1754–1764. cowan, e. a., powell, r. d. & smith, n. d. 1988: rainstorm394 glacier extent in a novaya zemlya fjord during the “little ice age” induced event sedimentation at the tidewater front of a temperate glacier. geology 16, 409–412. desloges, j. r., gilbert, r., nielsen, n., christiansen, c., rasch, m. & øhlenschläger, r. 2002: holocene glacimarine sedimentary environments in fi ords of disko bugt, west greenland. quat. sci. rev. 21, 947–963. elverhøi, a., lønne, o. & seland, r. 1983: glaciomarine sedimentation in a modern fjord environment, spitsbergen. polar res. 1, 127–149. forman, s. l. & polyak, l. 1997: radiocarbon content of prebomb marine mollusks and variations in the 14c reservoir age or coastal areas of the barents and kara seas, russia. geophys. res. lett. 24, 885–888. gilbert, r. 2000: environmental assessment from the sedimentary record of high-latitude fi ords. geomorphology 32, 295–314. heier-nielsen, s., heinemeier, j., nielsen, h. l. & rud, n. 1995: recent reservoir ages for danish fjords and mar ine waters. radiocarbon 37, 875–882. hughen, k. a., overpeck, j. & anderson, r. f. 2000: recent warming in a 500-year palaeotemperature record from varved sediments, baffi n island, canada. the holocene 10, 9–19. koryakin, v. s. 1986: sokrashcheniye oledeneniya na ostrovakh yevraziyskoy arktiki v xx veke. (decrease in glacier cover on the islands of the eurasian arctic during the 20th century.) pol. geogr. geol. 10, 157–165. loeng, h. 1991: features of the physical oceanographic conditions of the barents sea. polar res. 10, 5–18. lubinski, d. j., forman, s. l. & miller, g. h. 1999: holocene glacier and climate fl uctuations on franz josef land, arctic russia, 80° n. quat. sci. rev. 18, 85–108. mann, m. e., bradley, r. s. & hughes, m. k. 1999. northern hemisphere temperatures during the past millennium: inferences, uncertainties, and limitations. geophys. res. lett. 26, 759–762. matthews. j. a. 1991: the late neoglacial (‘little ice age’) glacier maximum in southern norway: new 14c-dating evidence and climatic implications. the holocene 1, 219–233. meeker, l. d. & mayewski, p. a. 2002: a 1400-year highresolution record of atmospheric circulation over the north atlantic and asia. the holocene 12, 257–266. mikhalov, v. i. & chizov, o. p. 1970: rezul’taty gliatsiologicheskikh issledovanii na novoi zemle v 1969 g. (scientifi c results of the glaciological investigations on novaya zemlya in 1969.) data glaciolog. stud. 17, 186–199. polyak, l., murdmaa, i. & ivanova, e. in press: a highresolution, 800-year glaciomarine record from russkaya gavan’, a novaya zemlya fjord, eastern barents sea. the holocene. smith, j. n. & schafer, c. t. 1987: a twentieth century record of climatologically-modulated sediment accumulation rates in a canadian fjord. quat. res. 27, 232–247. stuiver, m., reimer, p. j., bard, e., beck, j. w., burr, g. s., hughen, k. a., kromer, b., mccormac, f. g., van der plicht, j. & spurk, m. 1998: intcal98 radiocarbon age calibration, 24,000-0 cal bp. radiocarbon 40, 1041–1083. syvitski, j. p. m., burrell, d. c. & skei, j. m. 1987: fjords. processes and products. berlin: springer verlag. werner, a. 1993. holocene moraine chronology, spitsbergen, svalbard: lichonometric evidence for multiple neoglacial advances in the arctic. the holocene 3, 128–137. zeeberg, j. j. 2001: climate and glacial history of the novaya zemlya archipelago, russian arctic. amsterdam: rozenberg publishers. zeeberg, j. j. & forman, s. l. 2001: changes in glacier extent on north novaya zemlya in the twentieth century. the holocene 11, 161–175. saloranta.indd 177saloranta & svendsen: polar research 20(2), 177–184 across the arctic front west of spitsbergen: high-resolution ctd sections from 1998–2000 tuomo m. saloranta & harald svendsen the structure of the oceanic arctic front west of spitsbergen is investigated using data from high-resolution ctd sections from september 1998–2000. below the fresher surface layer, the front appears as a temperature–salinity front situated near the shelf break. no clear corresponding front in density is found. our analysis suggests that barotropic front instability is a main factor in provoking subsurface cross-front exchange. the subsurface heat loss in the west spitsbergen current due to this exchange is estimated to be of the same order of magnitude as the heat loss to the atmosphere in the surface layer. t. m. saloranta, dept. of geophysics, university of oslo, box 1022 blindern, n-0315 oslo, norway; h. svendsen, geophysical institute, university of bergen, allégaten 70, n-5007 bergen, norway. the oceanic arctic front west of spitsbergen marks the boundary between two different water masses: the warm atlantic type water (aw) in the west spitsbergen current (wsc) flowing along the continental slope, and the arctic type colder and fresher water (arw) onshore on the continental shelf (fig. 1). while numerous studies on the wsc have been published (see, e.g. gascard et al. 1995; saloranta 2001), the properties and origin of the shelf waters are less documented. presumably, arw (and, seasonally, sea ice) is transported by the east spitsbergen current, possibly joining with an extension of the bear island current, from storfjorden to the spitsbergen shelf where a mean northward flow prevails (johannessen 1986; loeng 1991; saloranta 2001) (fig. 1). the glaciers and rivers on the spitsbergen coast, especially within fiords, are additional freshwater sources. the arctic front west of spitsbergen is part of the larger and more or less continuous arctic front system in the nordic seas. its southward continuation is the arctic front in the barents sea (johannessen & foster 1978; loeng 1991; gawarkiewicz & plueddemann 1995; parsons et al. 1996; harris et al. 1998) and westward continuation the arctic front in the norwegian–greenland sea, west of the wsc (van aken et al. 1995). generally, the position of the fronts in the nordic seas is well correlated with bathymetry due to topographic steering of the currents (appendix a), and the drop in salinity across such a front is usually accompanied with a drop in temperature, which weakens the density gradient across the front (johannessen 1986). in contrast to, e.g. the arctic front in the barents sea, relatively little attention has been given to the arctic front west of spitsbergen. however, water exchange across this front may effectively dispose heat from the wsc, especially (i) in the subsurface water column (i.e. below 50 100 m) where the vertical heat flux to atmosphere is much reduced, and (ii) in the warm core of the wsc, which is situated next to the front over the upper part of the continental slope (boyd & d’asaro 1994; gascard et al. 1995; haugan 1999a; saloranta 2001) and which is an important transporter of heat into the arctic ocean (aagaard et al. 1987; bourke et al. 1988; gascard et al. 1995; manley 1995; haugan 1999b; saloranta & haugan 2001). locally, the varying influence of the aw on the shelf and in the fiords can affect the composition and distribution of ecosystems therein (e.g. benthos [blacker 1957]) as well as 178 across the arctic front west of spitsbergen the local sea ice conditions decisive for the access of marine traffic to the communities on spitsbergen in the winter months. in this study, the structure of the arctic front west of spitsbergen is investigated using data from high-resolution ctd sections crossing the front. background on the basis of topographic steering of currents (appendix a) and of knowledge of the wsc and slope–shelf systems in general we can anticipate the following main features in the slope–shelf system west of spitsbergen. (1) the warm aw core of the wsc (hereafter referred to as aw core) is, as already pointed out, confined over the upper continental slope where the maximum mean current speed has also been observed (fahrbach et al. 2001). in addition, an onshore thickening wedge of fresher surface waters over the shelf (and partly over the slope) was revealed in the mean hydrographic crossslope structure presented by saloranta (2001). (2) the arctic front resides near the shelf break between (i) the aw in the swift wsc, which is topographically well steered along the rather smooth isobaths of the steep slope (hanzlick 1983; jónsson et al. 1992; poulain et al. 1996; woodgate et al. 1998), and (ii) the arw on the relatively flat shelf, where the bottom topography is more irregular and characterized by banks and valleys (fig. 2). owing to the ragged shelf bottom topography, the mean flow is probably weaker on the shelf than over the slope (boyd & d’asaro 1994), consisting of more variable and rather closed circulation cells (see sætre 1999). as the shelf break is generally found around 300 m depth, the front would be confined to the about 0 300 m layer. moreover, condie (1993) showed theoretically that a density front will tend to intersect the bottom close to the shelf break. studies of the arctic front in the barents sea (johannessen & foster 1978; gawarkiewicz & plueddemann 1995; parsons et al. 1996; harris et al. 1998) have indicated that the front there is indeed well correlated with bathymetry, moving about ± 5 km back and forth at the surface due to tides. as the slope west of spitsbergen is much steeper than the slope in these studies, even stronger topographic steering can be anticipated in our case. (3) while topographic steering of currents may inhibit cross-front exchange, there are numerous mechanisms that can act the other way (huthnance 1995; brink 1998). for example, baroclinic and barotropic instability, wind forcing in the surface layer as well as the many submarine valleys and other topographic irregularities on the shelf likely affect the current patterns, provoke front instability (meandering, vortexes) and enhance cross-front exchange via ageostrophic effects (friction, nonlinearities, small spatio-temporal scales) relaxing the conditions required for topographic steering (appendix a) (huthnance 1995; brink 1998). moreover, since the current speed and net volume transport are likely much larger in the wsc than on the shelf, it would be more likely to find remnants of the slope water (i.e. aw) on the shelf than remnants of the shelf water over the slope. while the role of the shelf waters in the wsc cooling is still rather uncertain, the relatively light ice conditions in the spitsbergen fiords lacking a shallow sill (undocumented, but familiar to individuals with local experience) qualitatively suggest that the contribution of the aw to the oceanic heat flux therein is significant. data and methods during the three cruises of r/v håkon mosby in 1998–2000, each year in september, several fig. 1. schematic illustration of the current patterns in the sea west of svalbard, based on johannessen (1986), loeng (1991) and gascard et al. (1995). grey shaded arrows denote warm currents of atlantic origin and black arrows colder currents of arctic origin. dashed line denotes the arctic front west of spitsbergen. arctic ocean fram strait greenland sea bjørnøya current west spitsbergen current spitsbergen east spitsbergen current 80° n 78° n 76° n 74° n 72° n 18° w 18° e0° 179saloranta & svendsen: polar research 20(2), 177–184 ctd sections were conducted across the slope and the shelf using a towed undulating seasoar ctd instrument (see orvik et al. 1995). this data reveals the hydrographic structure within the 0 250 m layer with a horizontal resolution of 1 3 km. five of these sections (s1–s5) are presented here (fig. 2, table 1). the total length of these sections is about 500 km. the data is post-processed and pressure averaged to depth intervals of 2 m. as no rigorous calibration against water samples was done, the accuracy of the seasoar ctd is not exactly known. however, since we are focussing on changes in temperature and salinity rather than on the absolute values, the precision (random error) of the seasoar ctd is more relevant in our context. it is ± 0.005 °c and ± 0.005 ms (≈ ± 0.006 psu), which is more than adequate for our purpose. the 34.9 psu isohaline is used here to roughly demarcate the more saline aw from the fresher arw (swift & aagaard 1981; manley 1995). the 300 m isobath (fig. 2) is chosen to mark the shelf break (hereafter referred to as sb). results we first present the temperature–salinity (ts) structures of the five ctd sections (figs. 2, 3) and then outline some qualitative features of the corresponding density structures (fig. 4). in the following we speak in terms of 25 m depth intervals (0, 25, 50 m,...). in 1998, the southern subsection of s1 reveals the aw core over the upper slope, i.e. between about 300 1000 m isobaths. the corresponding ts front, below the 0 25 m layer, is scarcely resolved at the beginning of the section on the quite narrow and steep part of the shelf. in the northern subsection of s1, the aw core is abruptly terminated below 75 m depth near (slightly offshore) the sb, where a strong vertical ts front is observed (note that the slope is steeper here than in the southern subsection, possibly causing the aw core to contract horizontally due to topographic steering). remnants of aw are found onshore of the ts front, and above it, a tongue of aw stretches onshore around 50 m depth under a fresher and strongly stratified surface layer extending over the upper slope. the hydrographic structure is very uniform in the 35 km long alongslope subsection which links the southern and northern subsections. in 1999, in s2 the aw core extends onto the shelf about 20 km onshore of the sb. the corresponding front is most distinct in salinity, but is associated with a temperature front below about 50 m depth. a small slightly colder and fresher intrusion is seen about 10 km offshore of the sb. section s3 repeats partly the track of s1 taken one year earlier. although the aw core in s3 is more extensive than in s1, the ts maxima lie similarly over the upper slope and the aw core is fading offshore. a ts front is observed near (slightly onshore) the sb in the 25 200 m layer, and some remnants of aw are seen onshore of this ts front, as in s1. noteworthy is also the onshore thickening wedge of fresher surface water with subsurface temperature maximum. in 2000, in s4 a ts front is again found near the sb below the fresher surface water wedge. on the shelf, extensive but somewhat “eroded” remnants of aw are observed. the last section, s5, runs over the tracks of s1 and s3. also this section reveals extensive aw remnants near and onshore of the sb, below a fresher surface water wedge. especially noteworthy is the aw column over the sb, which seems to be detaching from the rather uniform aw core, as it is already separated from this core by a narrow vertical column of arw. the density structures of s1–s5 (fig. 4) reveal section date starting at ending at duration tide at the sb wind s1 6–7 sept. 1998 78.7° n, 9.9° e 79.0° n, 10.7° e 15.5 h 1 h and 1⁄2 h after l 8 m s-1, 310° s2 7–8 sept. 1999 77.6° n, 9.8° e 77.7° n, 12.1° e 4.5 h 1 h after h 13 m s-1, 95° s3 14 sept. 1999 79.0° n, 6.7° e 79.0° n, 11.4° e 7 h 1⁄2 h after l 10 m s-1, 165° s4 7–8 sept. 2000 77.7° n, 14.2° e 77.2° n, 10.9° e 7.5 h 3 h after l 7 m s-1, 120° s5 9 sept. 2000 79.1° n, 7.7° e 79.0° n, 11.1° e 5.5 h 3 h after l 6 m s-1, 65° table 1. information on the sections s1–s5. the column “tide at the sb” gives the phase of the semidiurnal tide at the time when the section is crossing the shelf break (l denotes low water and h high water). values correspond to tide at longyearbyen (s2 and s4) and ny-ålesund (s1, s3 and s5), svalbard. the column “wind” gives the average wind speed and direction during the section, as measured by the weather station on r/v håkon mosby. 180 across the arctic front west of spitsbergen generally no clear subsurface density fronts associated with the ts fronts, but isopycnals connect the aw and arw across the ts front. a stronger subsurface horizontal density gradient is rather seen on the offshore side of the aw core, which is associated with a trough of lighter water (this feature is resolved by s1 and s3, and was also revealed in the mean hydrographic cross-slope structure presented by saloranta [2001]). a density front is, however, found in the surface layer (fig. 4). this front is associated with the fresher shelf waters often appearing as a wedge. this wedge extends variably also over the upper slope capping parts of the aw core (especially in s1). discussion the arctic front west of spitsbergen can seemingly be divided into two, surface and subsurface fronts. the subsurface front, which will be our main focus here, is a ts front between the aw core and the shelf waters, where due to the balancing ts changes no clear density front is formed. as anticipated in the background section, above, it is often capped by a shallow (0 50 m) and usually onshore thickening layer of fresher waters in which the surface front, rather strong in density, is found. the salinity stratified surface layer is influenced by surface phenomena, such as freshwater supply from glaciers and rivers (especially via the major fiords of spitsbergen), wind forcing, heat exchange with atmosphere and solar heating, which explains the large variability in its ts properties and in the surface front position. many of the observed features of the subsurface front also agree with the expectations outlined earlier. for example, the aw core is observed over the upper slope and the arctic front is most often found near the sb. the subsurface front seems to extend down to near the bottom, although the temperature contrast in particular fades somewhat with depth due to cooler aw at deeper levels. in s2, the subsurface front and the aw core extend anomalously far onshore over the shelf, deviating somewhat from what we anticipated above. this might, however, be a reversible situation, a temporary deviation not contributing to net cross-front exchange. other sections show remfig. 3 (right). temperature and salinity in sections s1–s5. contours (black solid lines) are drawn for values ≥2 °c and ≥34.7 psu at 1 °c and 0.05 psu intervals. values lower than that are indicated by light blue dashed contours at 2 °c and 0.3 psu intervals. the colour bars in the upper right corner apply to all sections; the darkest blue colour indicates values ≤1 °c and ≤34.5 psu. black areas mark the bottom (based on sonar measurements on r/v håkon mosby), and white dashed line similarly bottom depth in decameters (10 m) according to the scale on the y-axis. yellow vertical dashed line marked with “s” denotes the position of the 300 m isobath (i.e. shelf break; see fig. 2), and magenta vertical dashed line marked with “t” a turning point in the section track. ticks at the surface denote “stations”, i.e. downward dives of the seasoar ctd. fig. 2. (a) the location of the seasoar ctd sections: s1 (red), s2 (black), s3 (green, dashed line), s4 (magenta) and s5 (blue). circles denote section starting points. bottom topography is based on jakobsson et al. (2000); solid contours show isobaths of 300, 600, 900 m..., and dotted contours 100 m (red) and 200 m (black) isobaths. (b) the bottom depth profiles of the ctd sections, based on the sonar measurements on r/v håkon mosby. vertical dashed lines denote the corresponding position of the 300 m isobath (i.e. the shelf break). (a) (b) 181saloranta & svendsen: polar research 20(2), 177–184 182 across the arctic front west of spitsbergen nants of aw on the shelf, which is indicative of irreversible cross-front exchange. in s4 the aw remnants seem to be relatively old, since their properties have faded, while in s5 a possibly new detaching remnant can be seen. moreover, as anticipated above, aw remnants are more usually observed on the shelf than arw remnants over the slope. as pointed out, many different mechanisms could cause such irreversible cross-front exchange. as there is no clear subsurface density front associated with the ts front, we can, however, as a “first order” approximation neglect processes connected to density fronts, such as baroclinic front adjustment and baroclinic instability. some of the aw “leaking” onto the shelf could be associated with the submarine valleys cutting across the shelf and deviating the topographically steered aw flow from the slope onto the shelf. the northern subsection of s1, as well as s3 and s5, run over such a valley (kongsfjordrenna), but only s5 reveals more extensive remnants of aw. the onshore deviating aw core in s2 might be connected to the about 300 m deep “niche” onshore of the sb (see bottom profiles in figs. 2, 3). aw remnants are, however, also found over fig. 4. potential density (σθ) of sections s1–s5. the colour bar in the upper right corner applies to all sections. solid contours are drawn for values ≥27.3 kg m-3 at 0.1 kg m-3 intervals. values lower than that are indicated by dashed contours at 0.3 kg m-3 intervals and by the lightest shading. vertical dashed lines marked with “s” and “t” denote the position of the 300 m isobath (i.e. shelf break; see fig. 2) and a turning point in the section track, respectively. ticks at the surface denote “stations”, i.e. downward dives of the seasoar ctd. 183saloranta & svendsen: polar research 20(2), 177–184 a bank in s4. therefore, while these valleys may assist leaking, the aw remnants are seemingly not only confined to them. tidal currents (max. 0.1 0.3 m s −1 according to kowalik & proshutinsky [1994]) are expected to cause only minor horizontal deviations of a few kilometres at maximum, e.g. in the front position. no clear coherence between the tidal phase (table 1) and the subsurface front position can be detected in our sections. coastal upwelling might sporadically bring aw onto the shelf. if the leaking seen in s2 was provoked by upwelling, we would expect to see also extensive capping of the aw core by the fresher surface layer. this is however not the case. the wind speeds (table 1) measured during the aquisition of the sections were generally low. moreover, the wind direction during s2 was easterly (the prevailing wind direction), which does not favour upwelling either. the structure of the few arw intrusions in our observations was rather vertically elongated, contrary to the thin lens-like intrusions observed by haugan (1999a). similar vertical shape characterized also parts of the subsurface arctic front. this would agree with the hypothesis that barotropic instability, arising from the velocity shear between the rather unidirectional and barotropic wsc (fahrbach et al. 2001) and presumably weaker but more complicated flow on the shelf, is an important source of frontal mixing generating waves and vortex fields near the sb and hence shedding remnants of aw onto the shelf and vice versa. although we cannot derive cross-front exchange rates from our hydrographic data only, we can give a rough order-of-magnitude estimate for the heat loss from the warm core of the wsc due to cross-front exchange. we first assume that the irreversible shelf–slope exchange is generally of order: slope current transport per 1000 km along the slope (huthnance 1995). a typical subsurface temperature difference of about 2 °c (fig. 3) between the slope (aw core) and the shelf waters would then indicate a slope current cooling of 0.2 °c/100 km along the slope due to crossfront exchange. this value corresponds well to the observed mean along-slope cooling of the wsc below 50 m, 0.2 0.4 °c/latitude (saloranta 2001). the cooling of 0.2 °c/100 km in, e.g. the 100 200 m layer would correspond to a mean vertical heat flux of about 100 w m−2, assuming a typical mean speed of 0.15 m s −1 for the part of the wsc confined over the upper slope (fahrbach et al. 2001). this subsurface heat loss is of the same magnitude as the mean surface heat loss to the atmosphere for the autumn season (häkkinen & cavalieri 1989), acting on, e.g. the 0 100 m layer. conclusions in the surface layer, the arctic front appears as a density front associated with fresher surface waters (usually appearing as an onshore thickening wedge). below this 0 50 m surface layer, the arctic front appears only as a ts front and a corresponding density front is missing. this subsurface arctic ts front seems to be confined near the shelf break and extends down near to the bottom. aw remnants found on the shelf provide evidence for significant irreversible cross-front exchange. the missing density front as well as the vertical shape in the ts front structures suggest that barotropic front instability is a main cause for subsurface cross-front exchange. the heat loss in the wsc due to this exchange can apparently be of the same order of magnitude as the surface heat loss to the atmosphere. acknowledgements.—we owe grateful thanks to captain ole magnus røttingen and his crew, peter haugan, tor gammelsrød, scientific engineers, as well as students onboard the 1998–2000 cruises of r/v håkon mosby. thanks also to those involved in the post-processing of the data and to the two anonymous reviewers. this study is a part of the research programme “arktisk lys og varme”, funded by the research council of norway. appendix a the topographic steering of currents arises from the conservation of potential vorticity. on the basis of the momentum and continuity equations, and when assuming no friction, hydrostatic conditions and homogeneous fluid, it can be shown that: (1) where q is potential vorticity, f is coriolis parameter (planetary vorticity), ζ is relative vor184 across the arctic front west of spitsbergen ticity, h is the depth of the water column, η is surface elevation, and u and v are the horizontal velocity components (û = uî + v ). assuming stationary conditions, |ζ| <<f, |η| << h, and in addition |∇ζ|<<|∇f | and |∇η| <<|∇h |, we get: , (2) which tells us that on an f -plane (constant f ) the current will follow contours of constant bottom depth, i.e isobaths. (for details see, e.g. gill 1982.) references aagaard, k., foldvik, a. & hillman, s. r. 1987: the west spitsbergen current: disposition and water mass transformation. j. geophys. res. 92(c4), 3778–3784. blacker, r. w. 1957: benthic animals as indicators for hydrographic conditions and climatic change in svalbard waters. fishery investigations, series 2, 20(10). ministry of agriculture, fisheries and food. london: her majesty’s stationary office. bourke, r. h., weigel, a. m. & paquette, r. g. 1988: the westward turning branch of the west spitsbergen current. j. geophys. res. 93(c11), 14065–14077. boyd, t. j. & d’asaro, e. a. 1994: cooling of the west spitsbergen current: wintertime observations west of svalbard. j. geophys. res. 99(c11), 22597–22618. brink, k. h. 1998: deep-sea forcing and exchange processes. in k. h. brink & a. r. robinson (eds.): the sea. vol. 10. pp. 151–167. new york: john wiley & sons. condie, s. a. 1993: formation and stability of shelf break fronts. j. geophys. res. 98(c7), 12405–12416. fahrbach, e., meincke, j., østerhus, s., rohardt, g., schauer, u., tverberg, v. & verduin, j. 2001: direct measurements of volume transports through fram strait. polar. res. 20, 217–224 (this issue). gascard, j.-c., richez, c. & rouault, c. 1995: new insights on large scale oceanography in fram strait: the west spitsbergen current. in w. o. smith & j. m. grebmeier (eds.): arctic oceanography: marginal ice zones and continental shelves. coastal and estuarine studies 49. pp. 131–182. washington d.c.: american geophysical union. gawarkiewicz, g. & plueddemann, a. j. 1995: topographic control of thermohaline frontal structure in the barents sea polar front on the south flank of spitsbergen bank . j. geophys. res. 100(c3), 4509–4524. gill, a. e. 1982: atmosphere–ocean dynamics. london: academic press. häkkinen, s. & cavalieri, d. j. 1989: a study of oceanic surface heat fluxes in the greenland, norwegian and barents seas. j. geophys. res. 94(c5), 6145–6157. hanzlick, d. j. 1983: the west spitsbergen current: transport, forcing and variability. phd thesis, university of washington. harris, c. l., plueddemann, a. j. & gawarkiewicz, g. 1998: water mass distribution and polar front structure in the western barents sea. j. geophys. res. 103(c2), 2905–2917. haugan, p. m. 1999a: structure and heat content of the west spitsbergen current. polar res. 18, 183–188. haugan, p. m. 1999b: on transports of mass, heat and carbon in the arctic mediterranean. phd thesis, university of bergen. huthnance, j. m. 1995: circulation, exchange and water masses at the ocean margin: the role of physical processes at the shelf edge. prog. oceanogr. 35, 353–431. jakobsson, m., cherkis, n. z., woodward, j., macnab, r. & coakley b. 2000: new grid of arctic bathymetry aids scientists and mapmakers. eos trans. 81, 89–96. johannessen, o. m. 1986: brief overview of the physical oceanography. in b. g. hurdle (ed.): nordic seas. pp. 103–127. new york: springer. johannessen, o. m. & foster, l. a. 1978: a note on the topographically controlled oceanic polar front in the barents sea. j. geophys. res. 83(c9), 4567–4571. jónsson, s., foldvik, a. & aagaard, k. 1992: the structure and atmospheric forcing of the mesoscale velocity field in fram strait. j. geophys. res. 97(c8), 12585–12600. kowalik, z. & proshutinsky, a. y. 1994: the arctic ocean tides. in o. m. johannessen et al. (eds): polar oceans and their role in shaping the global environment. geophysical monograph 85. pp. 137–158. washington d.c.: american geophysical union. loeng, h. 1991: features of the physical oceanographic conditions of the barents sea . polar res. 10, 5–18. manley, t. o. 1995: branching of atlantic water within the greenland–spitsbergen passage: an estimate of recirculation. j. geophys. res. 100(c10), 20627–20634. orvik, k. a., lundberg, l. & mork, m. 1995: topographic influence on the flow field off lofoten–vesterålen. in h. r. skjoldal et al. (eds.): ecology of fjords and coastal waters. pp. 165–175. amsterdam: elsevier science. parsons, a. r., bourke, r. h., muench, r. d., chiu, c.-s., lynch, j. f., miller, j. h., plueddemann, a. j. & pawlowicz, r. 1996: the barents sea polar front in summer. j. geophys. res. 101(c6), 14201–14221. poulain, p.-m., warn-varnas, a. & niiler, p. p. 1996: near-surface circulation of the nordic seas as measured by lagrangian drifters. j. geophys. res. 101(c8), 18237–18258. saloranta, t. m. 2001: hydrographic structure of the sea west of svalbard along and across the continental slope. reports in meteorology and oceanography 2. university of bergen. saloranta, t. m. & haugan, p. m. 2001: interannual variability in the hydrography of atlantic water northwest of svalbard. j. geophys. res. 106(c7), 13931–13943. swift, j. h. & aagaard, k. 1981: seasonal transitions and water mass formation in the iceland and greenland seas. deep-sea res. 28a, 1107–1129. sætre, r. 1999: features of the central norwegian shelf circulation. cont. shelf res. 19, 1809–1831. van aken, h. m., budeus, g. & hähnel, m. 1995: the anatomy of the arctic frontal zone in the greenland sea. j. geophys. res. 100(c8), 15999–16014. woodgate, r. a., schauer, u. & fahrbach, e. 1998: moored current meters in the fram strait at 79° n: preliminary results with special emphasis on the west spitsbergen current. ber. fachber. phys. 91. bremerhaven: alfred wegener institute for polar and marine research. piechura.indd 233piechura et al. 2001: polar research 20(2), 233–240 volume, heat and salt transport by the west spitsbergen current jan piechura, agnieszka beszczynska-möller & robert osinski during the summer of 2000 (june–july) 14 ctd and adcp transects perpendicular to the west spitsbergen current and along the western border of the barents sea were made. the measurements covered the area between 69° 43’ and 80° n and 01° and 20° e. the main purpose was to follow changes in volume, heat and salt content of atlantic water (aw) on its way north. the strongest and most stable flow of aw was located along the continental slope where northward flowing currents exceeding 40 cm/sec were measured. a few weaker northward branches were also found to the west of the slope. south-directed currents were recorded between them and eddy-like mesoscale structures were commonly observed. measured by vessel-mounted acoustic doppler current profiler (vm-adcp), the net northward transport of aw volume in the upper 136 m layer decreased from nearly 6 sv at the southernmost transect to below 1 sv at a latitude of 78° 50’ n. similarly, heat transport drops from about 173 tw to about 9 tw and relative salt transport (over 34.92 psu) from 980 × 103 kg/sec to 14 × 103 kg/sec. transport in the southern direction prevails at the transect located between 79° 07’ and 79° 30’ n. the calculated baroclinic geostrophic transport of aw volume, heat and salt in the upper 1000 m layer behaves similarly. east-directed transport dominates at the barents sea boundary while westward flow prevails on the western side of the west spitsbergen current. j. piechura, a. beszczynska-möller & r. osinski, institute of oceanology, polish academy of sciencces, ul. powstancow warszawy 55, 81-712 sopot, poland. the greenland, iceland and norwegian seas play a unique role in the circulation of the world’s oceans. they control the main exchange of heat and salt between the atlantic and arctic oceans. the principal source of heat and salt for the arctic ocean is the north atlantic ocean. atlantic water (aw), a surface water mass associated with a temperature and salinity maximum, enters the norwegian sea across the iceland–scotland ridge at a temperature of 6 to 8 °c and a salinity of 35.1 to 35.3 psu (maslowski 1994). the transport of such a large amount of heat causes the abnormally warm climate of north-west europe and the nordic seas. this region’s climate is 5 10 °c warmer than the zonal mean. aw is carried to the north by the norwegian atlantic current (nwatc). this current splits into two branches. one is driven to the east as the north cape current enters the barents sea where aw is significantly modified before reaching the central arctic (hopkins 1991). the branch moving towards the north becomes the west spitsbergen current (wsc). as it approaches fram strait, the aw partly recirculates back into the greenland sea to become intermediate water with a salinity of ca. 34.9 to 35.0 psu and a temperature of about ′ ′ ′′ 234 volume, heat and salt transport by the west spitsbergen current 0 °c to 2 °c. the remaining part of aw enters the arctic ocean through fram strait. when aw leaves the nordic seas through fram strait it has a salinity of about 35.0 psu and its temperature is about 5 °c lower than it was upon entry (maslowski 1994). until the 1970s, the only measurements of the nwatc and wsc were ctd observations and transport was estimated assuming geostrophy. the first current meters were deployed in fram strait over the spitsbergen continental slope (aagaard et al. 1973). the results show a strong barotropic component in the measured currents. estimates of volume transport for the wsc are summarized in table 1. the best and the most complete current measurements were recently carried out within the scope of the veins project, but the data are still being processed. in recent years, oceanographers have begun using a revolutionary current meter, the acoustic doppler current profiler (adcp), which, together with gps, provides quasi-continuous measurements of currents along ship routes. unfortunately, due to technical problems there are not many papers based on vessel-mounted adcp measurements in the nordic seas. vesselmounted adcp (vm-adcp) data were analysed for measurements in the arctic frontal zone in the greenland sea (van aken et al. 1995), in the barents sea polar front (gawarkiewicz & plueddemann 1995; parsons et al. 1996) and the barents sea opening (haugan 1999), as well as for the svinoy section in the norwegian sea (orvik et al. 2000). to the best of our knowledge, this is the first publication using vm-adcp data in the wsc region. the aim of this presentation is to describe changes in volume, heat and salt content of aw on its way from the northern coast of norway up to fram strait. some results of studies on flow dynamics and structure are also presented. vm-adcp data throughout the cruise, the 150-khz bb-vm adcp (rd instruments, san diego) mounted in the hull of r/v oceania was used to obtain vertical profiles of current speed and direction in the upper layer. the adcp reached the maximum depth of measured currents at about 400 m, but due to quality control, it was reduced to only 150 m. the adcp measurements do not comprise the sea surface, in our case the 0 16 m layer. the depth bin length was set to 8 m. the adcp data were averaged in 5 minute ensembles equivalent to 0.75 km horizontally at a speed of 5 knots. these settings produce a random error in the horizontal velocity component of about 0.95 cm/sec (rd instruments 1989). current measurements included in calculations were collected when the ship sailed at speeds from 4 to 6 knots and with no change in direction. the minimum percentage of good pings in the ensemble was set to 75 and the error velocity was set at 10 cm/sec. most of the measurements were done in regions where depth is greater than the range of the adcp bottom-track (ca. 500 m) so we had to rely on navigation as a reference. in this case, the crucial parameter for data quality is the misalignment angle. to solve this problem, transects were run partly in the shelf region where bottom-track and navigation reference were available and this allowed us to calculate the misalignment angle. the procedure was repeated for each transect (osi ski 2000). at the moment the adcp data are not detided. however, the tides cannot be completely discarded. measurements during veins revealed tidal currents up to 7 10 cm/sec on the west spitsbergen slope (woodgate et al. 1998). tidal velocities are considerably lower in deep regions and do not produce significant error in adcp data there, although they are an unknown contribution to the measured flow field. hydrographic data between 23 june and 14 july, fourteen ctd transects were performed, comprising an area between 69° 43’ and 80° n and 01° and 20° e (fig. 1). more dense coverage was carried out in the sørkapp region and along the north-western part of the svalbard shelf. data were collected using a seabird 9/11+ ctd probe. results the broad flow of aw, over 300 miles wide at the southernmost section, narrows on its way northward to less than 100 miles (fig. 1). the very narrow flow of aw at 75° n is caused by both strong cyclonic and anticyclonic eddies. the core 235piechura et al. 2001: polar research 20(2), 233–240 of the aw is situated at a depth of about 100 m on average (fig. 2). on the western side of the stream and in the cyclonic eddies around bjørnøya (bear island) and sørkapp, the core is found at a depth of ca. 50 60 m. in the centres of anticyclonic gyres it is pushed down to a depth of more than 200 m, reaching a maximum depth of nearly 300 m at 76° n, 13° 40’ e. this very strong anticyclonic eddy, together with the intensive cyclonic one to the west of sørkapp, results in large horizontal gradients of temperature and salinity and significant baroclinic transport to the south-east. the maximum temperatures in the core of aw are observed in the upper layer of ca 40 m, reaching about 8 9 °c in the south and decreasing slowly to about 6 °c at the entry to fram strait. that means this water was a bit warmer than usual. a similar tendency is discernible in temperature distribution at the 100 m depth (fig. 1); however, its horizontal gradient towards the north is less than in the upper layer. maximum salinity found in the aw drops very little, from about 35.2 to 35.11 psu, in the same area. the depth of maximum salinity along the main stream of aw (fig. 2) is perceptibly disturbed by meanders and eddy-like structures. aw occupies most of the passage between norway and bjørnøya and part of the bjørnøya–sørkapp opening, namely the storfjordrenna. adcp data (fig. 3) generally confirm circulation patterns already indicated by t, s distributions (figs. 1 and 2). there are signs of many eddy-like features, both cyclonic and anticyclonic, which result in frequent current direction reversal and opposite flows across the measured sections. the strongest currents were observed along the continental slope (fig. 4) and a speed of over 40 cm/sec was recorded in the surface layer. the second area of high current speeds is located in the close vicinity of ridges and the fracture zone. in the area of 73° to 73° 30’ n and 05° to 08° e, strong currents cross mohn’s ridge and exit the research area to the west. these waters probably come back to the research area farther north between 75° and 76° 30’ n. this could be the reason why at the more northern transect n (76° 30’ n) transport is significantly higher than that found farther to the south at transect kk (75° n; fig. 5, table 2). the fact that properties of water at the westernmost stations of transect hh and n are similar seems to confirm this assumption. strong currents were measured in the northern part of the svalbard shelf, where knipovich ridge comes close to the continental slope and the deep area narrows. to the north of knipovich ridge currents turn to the west and even partly back to the south. at the northernmost transect in fram strait, splitting of the main stream into two separate branches is apparent: one branch of the wsc turns right and another one turns left. accordingly to manley (1995), the former stream represents the svalbard branch, the largest influx of aw into the arctic ocean, and the latter one can be identified as the yermak branch. when comparing currents at 50, 100 and 150 m depths, one can see that the circulation pattern is preserved at all these depths. current speed decreases but only in the southern part, while north of 76° high values are maintained as well. the volume transports in the 136 m surface layer (depth from 16.2 m up to 152.2 m) calculated from adcp data (fig. 5) show a decrease in the northward transport from over 7 sv in the south to about 1 sv in the north; the south directed transport behaves similarly. there are also some exceptions, for example, the increase of northward transport between 75° and 76° 30’ n. as mentioned earlier, some additional inflows from the west could occur. another explanation could be that the transect along 75° n is too short in the western direction and does not catch all the transport to the north. the increase of southtable 1. west spitsbergen current transport estimates by various researchers. author transport (sv) remarks leonov (1947) 2.5 78° n section hill & lee (1957) 1.1 (3.2 max.) 74° 30’ n upper 400 m with 750 db reference (1949–1956) kislyakov (1962) 3.2 ± 1.5; 0.5 min. summer/ 5.5 max. winter 74° 30’ n section with 1000 db reference (1954–59) timofeyev (1962) 3.1 ± 0.6 78° n section with 1000 db reference from annual estimates 1933–1960 aagaard et al. (1973) 8.0 79° n using current meter data 1971–72 and hydrography hanzlick (1983) 5.6; 11.9 max. dec./ 1.4 min. march 79° n using current meter data 1976–77 and hydrography 236 volume, heat and salt transport by the west spitsbergen current f ig . 1 . h o ri zo nt al d is tr ib u ti o n of p ot en ti al t em p er at u re a t th e d ep th o f 10 0 m . f ig . 2 . h o ri zo nt al d is tr ib u ti o n of t h e m ax im u m s al in it y d ep th . 237piechura et al. 2001: polar research 20(2), 233–240 f ig . 3 . c u rr en t st ic k s at 5 0 m l ev el . f ig . 5 . n o rt hw ar d an d so u th w ar d a d c p m ea su re d tr an sp o rt a cr o ss t ra n se ct s. 238 volume, heat and salt transport by the west spitsbergen current bound transport at the mouth of isfjord could be caused by freshwater outflow from that fiord. the calculated baroclinic geostrophic currents above a 1000 db reference level reveal alternatively changing directions in most sections. this fact confirms the important role of the mesoscale eddy-like structures travelling with the main flow of aw to the north. the strongest baroclinic forcing occurred along the continental slope where the main branch of aw can be found (fig. 4). fig. 4. (a) vertical distributions of the perpendicular component of adcp measured current, and (b) calculated baroclinic geostrophic current with reference level 1000 m at transect s. table 2. adcp measured transport across transects. part of transect occupied by aw total area of transect (16.2 150.2 m) (salinity >34.92 psu) trantransect transect volume heat total salt relative salt volume heat total salt relative salt sect latitude length transport transport transport transport transport transport transport transport (km) (sv) (tw) (103 kg/sec) sref = (sv) (tw) (103 kg/sec) sref = 34.92 psu 34.92 psu (103 kg/sec) (103 kg/sec) (positive values = northward transport; negative values = southward transport) aa 69° 43’ 583.08 5.58 172.9 217188.4 982.5 5.74 173 217339.1 977.6 72° 44’ n hh 73° 30’n 371.13 2.1 49.42 74649.2 286.6 2.04 45.8 68743.5 316.6 kk 75° n 266.75 1.14 40.2 58192.9 266.7 1.03 39.9 57839 275.5 n 76° 30’ n 285.50 3.17 56.4 97646.2 333.2 3.07 54 94494.7 397.4 s 77°03’ 290.28 1.1 14.77 30619.5 13.9 0.9 12.9 24491.4 96.4 78° 10’ n z 77° 51’ 209.13 1.2 12.2 29546.2 12.3 0.72 10.7 21034.2 78.9 78° 19’ n eb2 78° 50’ n 113.36 0.85 8.05 17357.1 10.4 0.95 8.9 17357.1 14.1 xx 79° 07’ 103.16 -0.1 -1.85 -4349.3 -4.4 -0.09 -2.01 -3912.5 -4.01 79° 30’ n x 79° 32’ 136.95 1.04 19.4 40094.4 108.8 0.98 18.25 37826.1 109.5 79° 50’ n (a) (b) 239piechura et al. 2001: polar research 20(2), 233–240 the calculated current speed varied there from 15 20 cm/sec in the south to 30 40 cm/sec in the north. the second strongest branch of aw was located mostly along the ridges on the western side of our transects. it is also possible that this stream belongs to an edge of the greenland gyre and therefore should be treated not as a real northward transport of aw but as a part of recirculation. modelling mass balances of the arctic ocean (rudels 1987) revealed that 50 % of all aw in fram strait recirculates to the south. the observed main stream can be recognized as the svalbard branch, which is the major source of aw into the arctic ocean, yet because of recirculation it represents only one third of the total aw supply north of 76° (after manley 1995). exceptionally weak baroclinic currents and transport were observed on the barents sea side and in particular between norway and bjørnøya. the calculated speed of baroclinic currents was not higher than 5 10 cm/sec. barotropic forces most probably dominated there. similar values were obtained at the bjørnøya–sørkapp section, except for the area immediately adjacent to sørkapp, where the estimated current speed exceeded 30 cm/sec. the calculated volume, heat and salt transport of aw is presented in table 3. it represents baroclinic geostrophic transport, which results from the flow component driven by horizontal density gradients and relative to the reference level of 1000 m. the net baroclinic transport of aw toward the north decreases from about 7 sv in the south to about 2 sv at the northern transects. at the northernmost section (79° 50’ n), the net transport is directed to the south-east. similarly, the amount of heat transported by aw drops from ca. 130 tw to ca. 30 tw; therefore, about 100 tw is lost to the atmosphere, the barents sea and surrounding waters. heat lost in the area to the west of svalbard is about 85 wm-2, which is a significantly lower value than during the wintertime (boyd & d’asaro 1994). relative salt transport (waters with salinity higher than surrounding waters 34.92 psu) also decreases about five-fold from more than 1000 × 103 kg/sec to ca. 200 × 103 kg/sec. corresponding data for the barents sea border indicate a very small baroclinic table 3. calculated geostrophic baroclinic transport across measured transects with the reference level of 1000 m. part of transect occupied by aw total area of transect (upper 1000 db) (salinity >34.92 psu) trantransect transect volume heat total salt relative salt volume heat total salt relative salt sect latitude length transport transport transport transport transport transport transport transport (km) (sv) (tw) (103 kg/sec) sref = (sv) (tw) (103 kg/sec) sref = 34.92 psu 34.92 psu (103 kg/sec) (103 kg/sec) (positive values = northward transport; negative values = southward transport) aa 69° 43’ 583.08 7.59 133.06 273257.4 1063.0 6.87 127.63 247540.2 1084.4 72° 44’ n hh 73° 30’n 371.13 4.27 61.83 153710.8 480.7 3.77 61.79 135659.8 489.3 kk 75° n 266.75 4.80 76.48 172796.5 653.2 4.56 78.88 164198.4 639.7 n 76° 30’ n 285.50 2.47 32.76 88884.8 257.4 2.25 33.12 81142.6 253.6 s 77°03’ 290.28 2.90 36.36 104208.5 265.5 2.62 36.69 94124.4 285.2 78° 10’ n z 77° 51’ 209.13 1.73 29.502 62201.2 250.2 1.90 29.73 68435.5 222.0 78° 19’ n eb2 78° 50’ n 113.36 2.24 32.447 80693.5 206.4 2.10 28.92 75412.3 228.2 xx 79° 07’ 103.16 1.93 31.651 69568.6 229.3 1.99 31.86 71655.5 222.2 79° 30’ n x 79° 32’ 136.95 -1.09 -13.533 -39079.5 -32.8 -0.93 -12.59 -33491.9 -64.5 79° 50’ n (positive values = eastward transport; negative values = westward transport) v1 71° 10’ 343.93 0.82 18.83 29657.6 64.5 0.72 16.05 25897.0 71.0 74° 15’ n v2 74° 32’ 204.01 0.58 5.237 20556.1 -131.8 0.10 0.93 3713.7 3.5 76° 17’ n 240 volume, heat and salt transport by the west spitsbergen current geostrophic transport of volume (below 1 sv), heat (16 × 1012 w) and salt (71 × 103 kg/sec) to the east. calculations for section u, bordering the measured area on the western side and running from 78° to 79° 30’ n and 01° to 03° 45’ e, reveal that westward baroclinic transport is equal to 1.3 sv volume, about 12 tw heat and 80 × 103 kg/sec salt. summary the movement of the whole system along the continental slope was observed. the calculated baroclinic geostrophic currents, as well as those measured by the ship-mounted adcp, confirm the existence of numerous mesoscale cyclonic and anticyclonic eddies in the main stream of the wsc. the baroclinic transport (upper 1000 m) and total transport measured by vm-adcp (16 152 m) are of the same order, suggesting that barotropic component of the flow prevails in the upper layer. the first results confirm this supposition. the adcp measurements allow us to calculate absolute geostrophic velocities (adcpreferenced) and total (baroclinic plus barotropic) transport. to obtain a profile of absolute geostrophic velocity, mean vertical (50 150 m layer) and horizontal (between two ctd stations) adcp measured perpendicular to transect component of velocity and vertical mean calculated baroclinic velocity for the same layer were compared. the difference was treated as the barotropic component. this method was used and described in detail by meinen et. al. (2000) and colelet et al. (1996). the calculations made for deep transects n, s and z (see fig. 1) show that the total adcpreferenced transport in the whole water column is two to three times higher than the baroclinic one referenced to the level of 1000 m. these calculations will be published soon in separate paper. the northward flow of aw carries a huge amount of heat and salt to the high latitudes; on its way from northern shores of norway to fram strait it loses about 100 tw of heat and 800 × 103 kg/sec of salt. results obtained thus far are preliminary; the data are very fresh and require further processing. references aagaard, k., darnall, c. & greisman, p. 1973: year-long current measurements in the greenland—spitsbergen passage. deep-sea res. 20, 743–746. boyd, t. j. & d’asaro e. a. 1994: cooling of the west spitsbergen current: wintertime observations west of svalbard. j. geophys. res. 99(c3), 22,597–22,618. cocelet, e. d., schall, m. l. & dougherty, d. m. 1996: adcp-referenced circulation in the bering sea basin. j. phys. oceanogr. 26, 1113–11128. gawarkiewicz, g. & plueddemann, a. j. 1995: topographic control of thermohaline frontal structure in the barents sea polar front on the south flank of spitsbergen bank. j. geophys. res. 100(c3), 4509–4524. hanzlick, d. j. 1983: the west spitsbergen current: transport, forcing and variability. phd thesis, university of washington, usa. haugan, p. m. 1999: exchange of mass, heat and carbon across the barents sea opening. in p. m. haugan: on transports of mass, heat and carbon in the arctic mediterranean. phd thesis, university of bergen. hill, h. w. & lee, a. j. 1957: the effect of the wind on water transport in the region of the bear islands fisheries. proc. r. soc. london, ser. b, 148, 104–116. hopkins, t. s. 1991: the gin sea—a synthesis of its physical oceanography and literature review 1972–1985. earth sci. rev. 30, 175–318. kislyakov, a. g. 1962: fluctuations in the regime of the spitsbergen current. in: soviet fisheries investigations in the northen european seas. pp. 39–49. moscow: polar research institute of marine fisheries and oceanography. (in russian.) leonov, a. k. 1947: experimental quantitative computation of the transport of water, heat and salts into the arctic basin by the atlantic and pacific currents. meteorol. hidrol. 5. manley, t. o. 1995: branching of the atlantc water within the greenland–spitsbergen passage: an estimate of recirculation. j. geophys. res. 100(c10), 20,627–20,634. maslowski, w. 1994: numerical modelling study of the circulation of the greenland sea. phd thesis, university of alaska. meinen, c. s, watts, d. r. & clarke, r. a. 2000: absolutely referenced geostrophic velocity and transport on a section across the north atlantic currents. deep-sea res. 47, 309–322. orvik k. a., skagseth, ø. & mork, m. 2000: atlantic inflow to the nordic seas: currentstructure and volume fluxes from moored current meters, vm-adcp and seasoar-ctd observations, 1995–1999. deep-sea res. i 48, 937–957. osi ski, r. 2000: the misalignment angle in the vesselmounted adcp. oceanologia 42(3), 385–394. parsons, a. r., bourke, r. h., muench, r. d., chiu, c.-s., lynch, j. f., miller, j. h., plueddemann, a. j. & pawlowicz, r. 1996: the barents sea polar front in summer. j. geophys. res. 101(c6), 14,201–14,221. rd instruments 1989: principles of operation: a practical primer. san diego. rudels, b. 1987: on the mass balance of the polar ocean, with special emphasis on the fram strait. nor. polarinst. skr. 188. oslo: norwegian polar institute. timofeyev, v. t. 1962: the movement of atlantic water and heat into the arctic sea basin. deep-sea res. 9, 358–361. van aken, h. m., budeus, g. & hahnel, m. 1995: the anatomy of the arctic frontal zone in the greenland sea. j. geophys. res. 100(c8), 15,999–16,014. woodgate, r. a., schauer, u. & fahrbach, e. 1998: moored current meters in fram strait at 79° n: preliminary results with special emphasis on the west spitsbergen current. ber. fachbereich phys. 91. alfred wegener institute. grenvillian u-pb zircon ages of quartz porphyry and rhyolite clasts in a metaconglomerate at vimsodden, southwestern spitsbergen j u . a . balasov, a . m . teben’kov, y. o h t a , a. n. larionov, a . n. sirotkin, l. f. gannibal and g . i. ryungenen balasov, ju. a , , teben’kov, a. m . , ohta, y . , larionov, a. n . , sirotkin, a. n . , gannibal, l. f. & ryungenen, g . i. 1995: grenvillian u-pb zircon ages from quartz-porphyry and rhyolite clasts in a metaconglomerate at vimsodden, southwestern spitsbergen. polar research 14(3), 291-302 proterozoic metasupracrustal rocks form a nnw-sse trending basement zone along the western coast of spitsbergen. the rocks show complex structures as a result of both caledonian and tertiary deformation, and most of the subordinate metaigneous rocks are not suitable for isotopic age determination. some zircon-bearing rocks were found in the southwestern part of spitsbergen and an attempt of u-pb dating was performed. u-pb dating was carried out on zircon fractions from quartz porphyry and rhyolite clasts in a meta conglomerate unit of the pyttholmen formation northwest of hornsund. southwestern spitsbergen. the pyttholmen formation is considered to be a lateral equivalent of the upper part of the gulliksenfjellet quartzite and in the same time as the upper part of the skiufjellet metavolcanites. therefore, the obtained ages are applicable to the age of the skilfjellet igneous activities. some of the dated samples are strongly schistose and their magmatic origin is difficult to confirm; the interpretation of the isotopic results is not well constrained; however, some explanations are possible which refer to the known geological conditions; an igneous age of siliceous volcanic rocks of ca. 1200 ma, inherited zircon ages of ca. 2500 ma and a regional metamorphic age of ca. 930 ma. the last age belongs to the grenvillian period and is conformable with the rb/sr whole rock age obtained from the garnet-biotite schists of the i s b j ~ r n h a m n a group underlying the skilfjellet metavolcanites. ju. a . balafou, a . n . larionou, l . f. gannibal and g. i . ryungenen. geological institute of kola science centre, russian academy of sciences, ul. fersman 14, 184200 apatity, russia; a . m. teben’kov and a . n . sirotkin, polar marine geological expedition, lomonosou, ul. pobeda 24, 189510 sr. petersburg, russia; y . ohta, norsk polarinstitun, p . 0. box 5072 majorstira, n-0301 oslo, norway. introduction pre-old red sandstone basement occurs along the western coast of spitsbergen. it is composed mainly of precambrian rocks (ohta 1994), except for limited occurrences of cambro-ordovician, low grade phyllites and subordinate amounts of carbonates and metabasic rocks, all of which were deformed and metamorphosed during the cale donian orogeny. the ages of these rocks are not well constrained, except for the high-pressure metamorphic rocks of motalafjella, middle west ern part of spitsbergen (dallmeyer et al. 1990; bernard-griffiths et al. 1993) and some cale donian ages from the south of bellsund (hauser 1982; dallmann et al. 1990). two unconformities were proposed within the precambrian successions of northern hornsund by birkenmajer (1959, 1975, 1992), the torellian and werenskioldian. the upper, torellian uncon formity is defined by the base of the slyngfjellet conglomerate (table 1, fig. l ) , and its north western extension was mapped in western wedel jarlsberg land by bjornerud (1990). a precambrian igneous complex, the eimfjellet group, has been known northwest of hornsund (hoe1 1918; orvin 1940) below the lower, wer enskioldian unconformity (table 1). it was stud ied in detail by birkenmajer (1959), birkenmajer & narebski (1960), smulikowski (1965, 1968), krasilseikov & kovaleva (1979), teben’kov (1983) and summarised geologically by bir kenmajer (1981, 1992), czerny et al. (1993) and ohta & dallmann (1994). a rhyolite conglomerate was described by smulikowski (1968) at vimsodden, nw of not tinghambukta (figs. 1 and 2) and considered to be a part of the middle member of the notting hambukta formation of the vimsodden subgroup of the eimfjellet group (table 1; birkenmajer 1992). the present paper reports some results of the u/pb zircon dating from the clast of quartz 292 j u . a . balasoa et al. table 1 . lithostratigraphy of the precambrian successions i n southern wedel-jarisberg land by birkenmajer (1992) and our proposal which is similar lo czerny et al. (1993). correlation of the upper virnsodden subgroup is unknown since it is bounded by faults o n both sides. vkf: vimrodden kosibapasset fault birkenmajer (1992) present paper group formation s of werenskioldbr. n of werenskioldbr. --- gbshamna phy. sofiebogen hoferpynten dol. sofiebogen (torellian event) slyngfjellet congl. deilegga (werenskioldian evenl) deilegga skalfjellet vimsodden eimfjellet (unexposed) steinvikskardet fjellet qtz. gulliksenflellet qtz. feldspathic qtz. revdalen isbjornharnna ariekammen lsbjarnhamna skoddefjellet + 2 5 g a porphyry and rhyolite and matrix from the meta conglomerate. geological outline and sample occurrences new mapping (ohta 6i dallmann 1994; czerny et al. 1993) indicates a major fault or fault zone from vimsodden t o kosibapasset (vkf, fig. l ) , part o f which was observed along the southern coast of vimsodden as a wide shear zone, includ ing several faults with associated sulphide min eralisation veins (czerny e t al. 1992). t h e area north of v k f shows the torrellian unconformity between the deilegga and the sofiebogen g r o u p s (fig. 1 ) . to the south of vkf. the eimfjellet and i s b j ~ r n h a m n a groups are distributed. t h e stratigraphic relation between these two areas is unknown. birkenmajer (1975, 1981) defined the werenskioldian event o n the southeastern side of austre torellbreen, north of v k f , where his eimfjellet g r o u p is unconforrnably overlain by the deilegga g r o u p . birkenmajer's deilegga g r o u p . however. has been reinterpreted as the gisharnna phyllites of the sofiebogen g r o u p a n d the eimfjellet g r o u p has been shown t o be a different igneous complex, the jens erikfjellet volcanites (fig. l), within the slyngfjellet con glomerate of the sofiebogen g r o u p , according t o our observations and czerny et al. (1993). t h e werenskioldian unconformity is therefore a mat ter of debate. t h e lower part of the vimsodden subgroup of birkenmajer (1992). most of his nottingham bukta formation, occurs t o the south of v k f , shown as a part of t h e gulliksenfjellet quartzite in fig. 1, and the upper part, his elveflya forma tion. t o t h e north, shown as the vimsodden sub group in fig. 1. a part of the nottinghambukta formation is considered here t o b e a lateral equiv alent of t h e upper part of the gulliksenfjellet quartzite and is termed the pyttholmen formation (czerny et al. 1993, table 1). t h e vimsodden subgroup (birkenmajer's elveflya formation) around vimsodden contains three or four beds of intensely deformed metadiamictites which have been considered tilloids. birkenmajer (1959, 1991) and harland (1978) considered them pre cambrian tillites; harland et al. (1993) considered them t o be lower vendian tillites. w e observed typical tillitic rocks in front of werenskioldbreen on the strike direction of the metadiamictites, but the continuation with the latter is unknown d u e t o wide glacier a n d quaternary covers. czerny et al. (1993) considered these diamictites t o be vendian tilloids. these new observations seem t o support t h e opinion of harland e t al. (1993); however, since both sides of the virnsodden sub group (fig. 1) are bounded by faults (fig. l), their stratigraphic position is unknown. t h e sampled meta-rhyolite conglomerate unit grenoillian u-pb zircon ages of quartz porphyry and rhyolite clasts 293 legend: 1 glacier and quaternary cover 2-4 sofiebogen group. 2: g l s h a p n a phyllites 3 hoferpynten carbonates 4 slyngfjellet conglomerates 5 vimsodden subgroup 6 jens erikfjellet volcanites 7-10 skilfjellet metavolcanites and gulliksenfjellet quartzites 7 metabasic rocks 8 gulliksenfjellet 9 metabasic rocks quartzites containing gabhro diabase and granite blocks 10 feldspathic quartzite at the base of the skilfjellet volcanites 11 isbj@mhamna group 12 deilegga group 13 faults the metaconglomerate unit is shown in solid black (exaggerated). vkf: vimsoddenkosibapasset fault. ... ;.,:;_... () .?,:.::;;..!!'.::' ._.... ... ; ..... :......_. 13 . i . :...:. .:.: place names: e: eimfjellet g: gangpasset j : jens erikfjellet k: kosibapasset p: pyttholmen s: slyngfjellet sk: skilfjellet v: vimsodden. square area: fig. 2 fig. 1 . geological map of southwestern wedel jarlsberg land, based on recent mapping (ohta & dallrnann 1994; czerny et al. 1993). occurs at pyttholmen, north of kvislodden, and in the frontal flat of werenskioldbreen (fig. 2). the conglomerate is a member of the pyttholmen formation of czerny et al. (1993) and has a total thickness of more than 150 m. one of the faults of vkf is inferred to occur along the southernmost coast of vimsodden. to the south of the fault there is a 30 m thick layer of biotite-bearing, green-grey phyllites which con tains large blocks of aphanitic basic rocks, gabbro diabases and diorite. each block is up to 5 m across and all are weakly metamorphosed. dark green phyllites (55 m) occur on the bottom of the shallow water between the pyttholmen island and the mainland. white-green quartzite (35 m) and a chlorite-sericite quartz schist (13 m) occur in the northern and middle parts of pyttholmen island, respectively. the southernmost part of the island consists of the sampled metaconglomerate unit (20 m). the clasts consist entirely of rhyolic rocks in the northern part of the unit. southwards, the content of quartz porphyry clasts increases, and some granite clasts can be observed in the sou thern part. the size and frequency of the clasts 294 ju. a . balafov et al. fig. 2 . distribution of the pvttholmen formation decrease to the south; therefore, a southward younging structure is tentatively deduced. at ca. 700 m north of kvislodden. an outcrop of green-grey phyllite occurs south of vkf. a white-grey, micaceous quartzitic schist (20 m), locally gritty. and a sandy phyllite with chlorite clots occur ca. 100 m south of the green-grey phyl lite. to the south of these is a grey siliceous phyllite (ca. 50 m) containing a thin dark rhyolite layer, possibly a lava, and angular clasts of dark reddish rhyolite. a grey quartz schist ( 1 5 m ) , containing large feldspar fragments, occurs in the southern part of this locality and has scattered clasts of rhyolite u p t o 35 cm in size. this rock is well stratified and seven graded units were counted, all showing southward-fining. these sil iceous phyllites and schists are located roughly in the strike direction of the metaconglomerate unit of pyttholmen and are correlated with the latter. some of the present authors consider that these phyllites and schists were originally siliceous lavas and pyloclastics, and not conglomerates. a phyllitic rhyolite (ca. 10 m thick), exposed isolately along a stream o n the southern frontal flat of werenskioldbreen, is considered t o be correlatable with the metaconglomerate unit of pyttholmen. neighbouring scattered exposures are micaceous quartz schists. a white quartzite, showing brecciated structures, occurs ca. 150 m northwest of the phyllitic rhyolite. this quartzite is traceable discontinuously t o the southeast o n t o the western ridge of angellfjellet, where i t turns back to the northwest along the lower part of bratteggelva. and joins with the major part of the gulliksenfjellet quartzite (fig. 2). a thin meta legend: 1 glaciers and quaternary cover 2 moraines 3 green-grey phyllites, locally containing gabbro diorite blocks schists quartzites rocks north of vkf. 4 mica-chlorite-quartz 5 gulliksenfjellet 6 skilfjellet metabasic 7 vimsodden subgroup black: metaconglomerate unit and its correlatable rhyolite. italic nos: localities of the dated samples rhyolite lens occurs in the gulliksenfjellet quartz ite c a . 7 0 0 m southeast from the mouth of bratteggelva. t h e quartzite contains sandy schist layers in its upper part on the eastern coast of nottinghambukta ( t h e nottinghambukta for mation of birkenmajer, 1992). these observations from vimsodden to not tinghambukta show that t h e pyttholmen for mation consists of quartzite, locally with greenish tint, a n d quartz schists similar t o t h e gul liksenfjellet quartzite and green-grey phyllites which locally contain blocks of coarse-grained igneous rocks, similar t o those commonly >den (czerny e t al. 1993) in the skdlfjellet subgroup of birkenmajer (1992). t h e skalfjellet and the vimsodden subgroups were thought t o be lateral equivalents by bir kenmajer (1959, 1992) and the gulliksenfjellet quartzite and the' skdlfjellet subgroup of bir kenmajer a r e laterally transitional (czerny e t al. 1993). w e consider that the pyttholmen for mation is a lateral facies variation of t h e upper gulliksenfjellet quartzite, and a t the same time, it is the western facies variety of the upper skdlfjellet subgroup (fig. 3). accordingly, the rhyolite a n d quartz porphyry clasts in t h e meta conglomerate unit of the pyttholmen formation a r e considered t o b e derived from t h e skdlfjellet subgroup, forming the westernmost distribution of the felsic pyroclastic-eruptive rocks of the sub group. it is difficult t o judge whether the clast bearing, strongly schistose rocks of the unit con sist totally of volcanic materials or contain certain amount of sedimentary components. solid clasts were chosen for t h e dating, but some schistose grenuillian u-pb zircon ages of quartz porphyry and rhyolite clasts 295 nw legend: 1 metaconglomerate unit of the pyttholmen 2000 formation quartzites (sandy) schists 2 gulliksenfjellet 3 mica-chlorite-quartz 4 metarhyolites 5 metabasic rocks with 1000. gabbro-diabase and granite blocks 6 green and green-grey phyllites 7 feldspathic quartzites 8 unexposed conformable with the the isbj0rnhamna group is 0 se angellfiellet fig. 3. lateral changes of litho-facies between the pyttholmen formation, the gulliksenf~ellet quartzites and the skslfjellet metavolcanic rocks, modified from czerny et al. (1993). table 2. modal composition of the dated rocks. symbols of minerals are after kretz (1983), except for feld (feldspars) and op. (opaque minerals). the remaining content of samples 3 , 5 , 6 and 7 are secondary and accessory minerals which are difficult to count due to fine grain size; +: recognised. -: not recognised. matrices were also included. the sedimentary materials, which may be mixed in the schistose samples, are considered to be derived from the same source as those in the upper gulliksenfjellet quartzite. samples seven samples zircon dating, each 50 % were collected from the metaconglomerate unit; the localities are given in fig. 2 , and their modal compositions are shown in table 2. samples 2 (fig. 4, left, clast) and 4 (fig. 4, right, clast) are brownish grey and reddish quartz porphyry clasts, respectively, ca. 50 cm in length, showing relict-porphyritic and -glomeroporphy ritic textures with 0.5-1 .o cm phenocrysts of quartz and k-feldspar. round outlines of clasts fig. 4. metaconglomerates. left: schistose rhyolite conglomerate, white rhyolite clasts in a grey schistose matrix (pyttholmen). middle: micaceous quartz schist, either the matrix of conglomerate or strongly schistose rhyolite (north of kvislodden). right: schistose rhyolite conglomerate; the clasts are dark in colour (north of kvislodden). 296 j u . a . balasov et al. are well preserved. but cataclastic textures are developed within the clasts. samples 3 (fig. 4, middle) and 5 (fig. 4, left. matrix) are schistose parts of the metaconglom erate and have lepidoand granoblastic textures. relict-porphyritic and glomeroporphyritic tex tures, consisting of up to 1 .o cm size quartz and k feldspar grains, are locally preserved. suggesting that these samples are strongly sheared rhyolite in rhyolitic pyroclastic. some amounts of the matrix of conglomerate may be incorporated in the samples, but they are impossible to evaluate petrographically. a significant amount of musco vite and a small amount of chlorite occur along the cleavages. the layers around these rocks contain dark reddish, elongated rhyolite clasts strongly penetrated by cleavages. sample 6 is a light grey-brown. phyllitic rhyolite in hand-specimen and is petrographically a micaceous quartz schist, similar to sample 3 and 5 . except that no chlorite has been observed. sample 1 has a greenish colour and is a finer grained siliceous rock compared to the others, lacking clasts of phenocrysts. sericite-chlorite aggregates are localised along cleavages in the granoblastic texture of quartz and feldspars. this seems t o be an aphanitic part of the rhyolite or sedimentary matrix. sample 7 is a dyke, 30 cm wide and 1.5 m long, that cuts the metaconglomerate. the dyke is restricted to the inside of the metaconglomerate unit and is considered to have formed soon after deposition bv segregation in a hot pyroclastic flow or segregated during a later metamorphism. the rock has a coarse-grained pegmatitic texture of quartz and feldspars and shows cataclastic frac tures. table 3 chemical composition of the dated rocks two analyses of smulikowslu (1968). 338m and 338c. are included as samples 8 and 9 , respectively the analyses were made at the sevzap geologija laboratory, st petersburg, russia, by the x-ray fluorescence method o n the k r f i 8 device chemical analyses of the dated rocks, together with two from smulikowski (1968) are shown in table 3. due to intense development of cleavages accompanied by distinctive amount of sericite, and locally chlorite, primary chemical com positions were strongly modified. especially the k 2 0 contents. strict considerations of an igneous rock group can not be made for the present rocks, since some of them may contain certain amount of sedimentary materials. apparently the rocks have very high k2o (aver age of 9 samples = 7.5%) and very low na,o (average of 9 samples = 0.47) contents (table 3). most of these rocks plotted in the rhyolite composition field on the total alkalis vs sioz dia gram (fig. 5a), except for sample l , a subalkaline dacite and samples 8 and 9 , trachytes. sample 8 has normative ans2 and is considered to be a glassy andesitic rock modified by later addition of k 2 0 . although smulikowski (1968) described it as a rhyolitic clast. sample 9 lacks specific petro graphic description in smulikowski (1968). the samples are scattered across the alkaline and sub alkaline field (fig. 5a, irvine & baragar 1971), and all subalkaline rocks have a calcalkaline nature (fig. 6, miyashiro 1974). tioz vs feo*/ mgo ratios (figure not shown) show a typical calcalkalic trend (miyashiro & shido 1975). samples 2 and 4 are clasts relatively free from penetrative cleavages, and a variation trend of total alkalis passing these two gives an alkali-lime index of ca. 52 5 -3 (figs. 5a and 5b). since a large addition of k 2 0 during later metamorphism is expected, the index will be higher in the primary rocks. i.e., alkali-calc and calc-alkali rock series. high k 2 0 and low n a 2 0 contents apparently show that the rocks are of the s-type (chappel & white 1974). the boundary between the sand i-type on the k 2 0 n a 2 0 diagram is more than 2 wt % n a 2 0 at 2 wt % k 2 0 (chappel & white 1974). the maximum nazo content of the present samples is 1.32 wt 70, therefore, even if some amounts of k 2 0 were considered to be secondary additions, the present samples remain within the s-type field in the diagram. although some samples may contain the matrix of conglomerate, some, at least samples 2 and 4, are solid igneous rock clasts and they are in the s-type field. this is supported by the trace element vari ations (table 4 and fig. 7 ) . since only four elements for standard spider diagram are avail able, fig. 7 is an unusual spider diagram and the analyses were normalised to the average i-type grenvillian u-pb zircon ages of quartz porphyry and rhyolite clmts 297 i i i 1 i . 1 8 a1 ~ 55 60 65 70 7 5 si02 wt % fig. 5. total alkalis and c a o vs sio, diagrams, two samples from smulikowski (1968), nos. 8 (smulikowski, no. 19, table 2) and 9 (smulikowski, no. 18). are included. 5a: total alkalis vs sio,. solid circles with numbers: present samples. a , variation trend of n a 2 0 + k,o, including the least modified rocks (samples 2 and 4); b, alkaline-subalkaline division after irvine & baragar (1971). broken lines, classification of felsic rocks; lined area, area of the felsic igneous rocks from the skilfjellet metavolcanic rocks (ohta, teben’kov and czerny, unpublished data). 5b: cao vs si02. same symbols as in 5a. dashed line, variation trend of cao . a a -m fig. 6 . afm diagram with two samples from smulikowski (1968) included. solid curve: tholeiite-calcalkalic boundary (ivrine & baragar 1971), area inside dashed-dot curves: field of common calcalkalic rocks (ringwood 1974), area inside dotted curve: scandinavian leptites (magnusson 1970; parak 1975; lundberg & smeuie 1979), solid circles and lined area: same as fig. 5a. granite (taylor & mclennan 1985). the present rocks reveal distinct differences from the i-type granite, but show general similarity to the s type, except for t i 0 2 v and ni, and rather good correlation with the pattern of the average shales (taylor & mclennan 1985), except for v, cr, ni table 4. trace element analyses of the dated rocks. the analyses were carried out in the vnii oceangeologija spectra laboratory of st. petersburg, russia. the values with an aster isk (*) are determined by mass-spectrometric analysis; nd = not determined; = not detected. av-i = average of the i-type; av-s = average of the s-type granites; av-sh = average of post archean shales. all three averages from taylor & mclennan (1985) are shown for reference. and co. the reasons of these dissimilarities can not be explained as in the case of definite igneous rocks, since they may contain some sedimentary materials. high values of cr can be explained by a possible supply of chromite from the gabbro anorthosite rocks of the skftlfjellet subgroup, which contain cumulate facies of chromite (czerny et al. 1993). the trace element charac teristics suggest an addition of areno-argillaceous materials into the present rocks, during both igneous and sedimentary processes. the high k 2 0 298 ju. a . balasorl et al. 101 a o ' t v 0.05 5 rb sr ba sc y ti zr v cr co ni cu ga f i g . 7. analysed trace elements normalised to the average 1 type granite, (taylor & mclennan 1985). vertical lines. present rocks, broken line. average s-type granites; dotted line. average post-archean shales (both from taylor & mclennan 1985). nature infers a crustal origin, if this nature is primary. it is difficult to state that all present samples belong to a comagmatic series from their chemical data. however, general similarities of chemical nature between the present rocks and the felsic rocks of the skilfjellet metavolcanites indicate that they belong t o the same igneous rock group, and this is supported by the observed lateral tran sition between this metaconglomerate unit and upper skiilfjellet subgroup. uncertainty of a co magmatic nature for the samples makes the inter pretation of isotopic results ambiguous; however, some considerations can b e attempted within the limit of data quality. t o b k 5. percentages of the two morphotypes of separated zircons m l = morphotype 1 : m-2 = morphotype 2. sample no m-1 m-2 i 70 30 100 0 3 100 0 4 98 2 5 99 5 6 95 10 7 90 7 zircons separated zircon grains were grouped into two morphotypes (table 5 and fig. 8): (1) intact crystals with (111) and (110) facets and their fragments, 0.07-0.1 m m in size, with length/width ratios of 1.2-1.5, a r e by far the most prevalent type. they a r e unzoned. transparent with smooth surface t o half-transparent with rough surface, mainly colourless. though some are pale pink in colour. (2) grains having complex natures are grouped together in this type. some have half-transparent inner and turbid (possible d u e t o rough surface) outer parts and show lilac colour, and are frag ments of idiomorphic grains. z o n e d grains rep resent u p to 2-3% of the total zircon population. some are rounded, and oval grains have scale like surfaces and tiny ridge-trough patterns o n the pyramidal facets, similar t o corroded grains (krasnobaev 1985). t h e fractions of this morpho type certainly contain some inherited o r detrital zircon grains. fig. 8 . examples of the morphotypes of the dated zircon grains. above: morphotype 1, fragment of idiomorphic grain. blow: morphotype 2, rounded and zoned grain. numbers in the figures are sample number and morphotype number. 11 12 31 41 51 61 62 71 72 i r a d lo g . l so lo p rd lo s a g e m ea su re d ls o to p ra ll o l o ad in g r a d lo g . c om m on u 20 6p b 20 6p b 20 6p b 20 7p b 20 7p b 20 6p b 20 7p b 20 7p b 20 6p b (m g ) p b @ p m ) p b@ pm ) (p pm ) 20 4p b 20 7p b 20 8p b 2 m p b er ro r% 23 5u er ro ff i 23 81 1 er ro r% rh o 20 6p b 23 5u 2 ~ 8 u 5. 00 34 .4 9 0. 41 17 5. 2 28 55 10 .8 1 4. 68 0. 08 8 0. 14 2. 15 0. 28 0. 18 0. 25 0. 87 13 80 11 64 10 51 1. 70 75 .1 3 0. 89 25 9. 1 29 68 7. 65 6. 14 0. 12 6 0. 33 4. 61 0. 40 0. 26 0. 22 0. 56 20 19 17 50 15 12 13 .0 0 33 .7 2 0. 54 13 9. 2 27 68 11 .8 5 2. 96 0. 07 9 0. 17 2. 19 0. 43 0. 20 0. 39 0. 91 11 83 11 78 11 75 4. 90 32 .1 0 0. 77 13 6. 9 16 29 11 .4 3 3. 20 0. 07 9 1. 41 2. 16 1. 43 0. 20 0. 23 0. 16 11 72 11 68 11 67 3 8. 20 15 3. 10 0. 87 67 0. 6 84 78 12 .2 6 4. 37 0. 08 0 0. 25 2. 25 0. 36 0. 20 0. 25 0. 71 11 98 11 97 11 97 3 s. 0. 30 21 7. 29 10 .7 0 98 2. 4 85 1 8. 51 5. 83 0. 10 2 0. 59 2. 92 0. 69 0. 21 0. 31 0. 52 16 59 13 88 12 19 a z a 4. 50 28 .3 4 0. 77 11 7. 0 15 55 11 .4 1 2. 26 0. 78 7 0. 26 2. 03 0. 44 0. 19 0. 35 0. 81 11 25 11 04 11 64 1. 50 31 .1 4 8. 29 16 3. 3 18 6 6. 39 2. 54 0. 08 3 1. 84 1. 95 1. 92 0. 17 0. 35 0. 31 12 70 io w i0 1 5 2. 50 87 .6 5 3. 24 28 3. 6 12 35 6. 87 6. 26 0. 13 5 0. 31 5. 28 0. 45 0. 28 0. 32 0. 72 21 67 18 65 16 06 9 6 3 '"0 d 2 g a 3 r t 4 w w 300 j u . a . balasori et al. analyse at the geochemical laboratory of kola science center. apatity, russia. samples 2, 3 . 4 . and 5 d o not contain enough amount of morpho type 2 zircon for analyses and sample 2-1 was unsuccessful in analysis. the treatment of zircons for dating following the procedure of krogh (1973). uranium and lead concentrations and lead isotopic composition were determined using an mi-1201-t mass-spec trometer with a single collector. employing a specially cleaned silica gel emitter and h 3 p 0 4 on the evaporating rhenium ribbon filament. the lead blank during the analysis was less than 0.5 ng and that o f uranium 0.05 ng. the analytical error of the isotope measurements of lead was 0 . 2 % . the error of the isotopic dilution techniques. using 2'jxph and z35u spikes is estimated to be 1 % . t h e analytical procedures were calibrated by running the all-union igfm-87 and nbs-981 standards. t h e age calculation has been done using the program of ludwig (1991a. b) results results o f the isotope analyses are shown in table 6 and figs. 9 and 10. samples 3, 4 and 5 plot closely to each o t h e r ; therefore. they are shown separately in fig. 9. specimen 4-1, which is a solid quartz porphyry clast with little penetrative cleavage, lies o n the concordia (fig. 9) and gives an age of 1198 ? -5 m a . samples 3-1 and 5-1 are slightly off from the concordia and a chord through them and 4-1 gives an upper intercept age of 1201 t -57 ma. t h e lower intercept of the chord. 924 ? -765 ma. is with a large uncertainty. since the cord is subparallel to the concordia, but a small partial resetting is suggested by the lower intercept. alternatively. samples 3-1 and 5-1 show an age a few million years younger than that of sample 4-1. as does sample 6-1 (fig. 10) which is almost on the concordia and shows ca. 1110 ma. the 1-1 and 1-2 zircon fractions define a chord with a lower intercept age of 919 f -16 ma and an upper intercept age of 2456 ? -31 m a (fig. 10). the two morphotype fractions from sample 7 yield a lower intercept age of 933 ? -9 ma and an upper intercept age of 2538 * 2 4 m a . t h e 6-2 fraction plots near the chord of the fractions from samples 1 and 7. t h e composite chord of the fractions 1-1, 1-2, 7-1, 7-2 and 6-2 gives a lower intercept age of 931 ? -54 ma and an upper intercept age of 2508 t -125 m a with m s w d = 9.5. t h e samples incorporated in this composite chord a r e phyllitic rocks and a peg matitic rock and the three fractions of morpho type 2 among them certainly contain inherited and/or detrital zircon grains. interpretation and conclusion d u e mainly to metamorphic modifications. the dated samples can not be proved by their co magmatic origin by petrographic and chemical examinations. t h e discords showing high upper intercept ages suggest the presence of detrital and/or inherited zircon grains in the samples, therefore some samples a r e not pure igneous rocks, but the matrix of conglomerate. it is dif ficult to give any conclusive interpretation of t h e isotopic data. however, since all dated samples are from o n e monomictic conglomerate unit, the clasts are supposed t o b e derived from the same igneous source and t h e matrix is the same material as the laterally equivalent gulliksenfjellet quart zies. s o m e explanations will be attempted based o n the assumption above, though alternative interpretations a r e possible. t h e concordia age of fraction 4-1 and the upper intercept age of the chord through fractions 3-1, 4-1 and 5-1 ca. 1200 ma, a r e considered t o b e t h e magmatic age of the rhyolite and quartz porphyry, since the zircon grains in these fractions are euhedral and homogeneous crystals. fractions 3-1. 5-1 and 6-1 may give younger ages of the igneous activity which prolonged for some million years. t h e lower intercept ages obtained by various chords a r e in a range of 919-933ma and are considered t o imply partial resetting by later regional metamorphism (fig. 10, i in inserted figure). this age is conformable with a pre liminary rb-sr whole rock age of 936 t -15 m a obtained from garnet-biotite schists of the i s b j ~ i r n h a m n a g r o u p by gavrilenko e t al. (1993). we tried isotopic analyses of some rocks from the group, but t h e results show a large scatter and unsuccessful. t h e isbj0rnhamna g r o u p is con formably underlying the skilfjellet subgroup (czerny et al. 1993; o h t a & dallmann 1994) at all observed localities of their contact. accord ingly, t h e regional metamorphism of a n inter mediate-pressure series, greenschist-middle amphibolite facies grade, which affected t h e grenuillian u-pb zircon ages of quartz porphyry and rhyolite clasts 301 skilfjellet igneous rocks and the sediments of the isbj@rnhamna group, is considered to be of qenvillian age. the upper intercept ages, ca. 2500 ma, ob tained from the fractions of samples 1, 6 and 7, suggest the presence of a late archean or early proterozoic crystalline basement that was either partly incorporated at depth or supplied detrital zircons at the surface to the present rocks (fig. 10, i1 in inserted figure). samples 1 and 7 have no sign of ca. 1100-1200 ma. this suggests that sample 1 is a sedimentary matrix of the met aconglomerate. sample 7, a pegmatitic rock, can be explained as a segregated dyke containing detrital zircon grains derived from the wall rocks, mainly matrix of the conglomerate. this inter pretation confirms that the lower intercept age of fig. 10 indicates a regional metamorphism, but not an igneous age. a similar, but somewhat young upper intercept age of ca. 2100ma, has been obtained as the protolith age of the eclogite in motalafjella about 150 km north along the western coast of spits bergen (bernard-griffiths et al. 1993). a meta morphic zircon age of ca. 2400 ma has been reported from the gneisses of the eskolabreen formation, structurally lowest lithological unit in southern ny friesland, northeastern spitsbergen (balasov et al. 1993). acknowledgemen&. t h e authors are grateful to the leadership of polar marine geological expedition for providing the oppor tunity of this geochronological work in svalbard. m. g. bjorn erud, miami university, ohio, u.s.a. and j. czerny and m. manecki, stanislaw staszic university of mining and metallurgy, krakow, poland, contributed very much during the field works. we thank a. livanova for the translation of the draft manuscript from russian. acknowledgements are also due to m. g. bjornerud, d . g. gee, university of uppsala, sweden, and k. birkenmajer, polish academy of sciences in krakow. poland for improvement of the english and critical comments. references balashov, yu. a . . lanonov. a. n., cannibal, l. f.. sirotkin. a . n . , tebenkov. a . m. ryungenen, g. 1. & ohta, y. 1993: an early proterozoic u-pb zircon age from an eskolabreen formation gneiss in southern ny friesland, spitsbergen. polar res. 12(2), 147-152. bernard-griffiths. j., peucat. j. j . & ohta, y . 1993: age and nature of some protoliths in the caledonian blueschist eclogite complex of western spitsbergen: a combined approach using u-pb, sm-nd and r e e geochemistries. lithos 30, 81-90. birkenmajer, k. 1959: report on the geological investigations of the hornsund area, vestspitsbergen. in 1958. part i. the hecla hoek formation. bull. acad. pol. sci., ser. sci. chim. ge61. gkol. gkogr., 7(2), 129-136. birkenmajer, k. 1975: caledonides of svalbard and plate tec tonics. bull. geol. soc. den. 24, 1-19. birkenmajer, k. 1981: the geology of svalbard, the western part of the barents sea, and the continental margin of scan dinavia. pp. 265322 in naim, e . m.. churkin. m. jr.. & stehli, f . g . (eds.): the arctic ocean. the ocean basins and margins 5, the arctic ocean, chap. 6 , 265-329. birkenmajer. k. 1991: origin of the vendian tilloids (early proterozoic). south spitsbergen. bull. acad. pol. sci., earth sci. 39, 39-40. birkenmajer. k. 1992: precambrian succession at hornsund. south spitsbergen. a lithostratigraphic guide. stud. geol. polon. 98, 67-105. birkenmajer, k . & narebski, w. 1960: precambrian amphibo lite complex and granitization phenomena in wedel-jarlsberg land, vestspitsbergen. stud. geol. polon. 4 , 37-82. bjornerud, m. g. 1990: upper proterozoic unconformity in northern wedel-jarlsberg land. southwest spitsbergen: lithostratigraphy and tectonic implications. polar res. 8, 127-140. chappel, b. w. & white. a . j. r . 1974: two contrasting granite types. pacific geol. 8, 173-174. czerny, j., lipien, g., manecki, a . piestrzynnski. a . 1992: geology and ore-mineralization of the hecla hoek succession (precambrian) in front of werenskioldbreen. stud. geol. polon. 98, 67-105. czerny, .i.. kieres, a,, manecki, m. & rajchel, j. 1993: geo logical map of the sw part of wedel-jarlsberg land, spits bergen 1:25.ooo, with the text. institute of geology and mineral deposits, university of mining and metallurgy, krakow. 61 pp. dallmann, w. k., hjelle. a , , ohta, y . , salvigsen, 0. bjornerud, m . g . , hauser, e. c.,maher, h. d. & craddock. c. 1990: geological map svalbard 1:100,000, b i l g . van keulenfjorden. norsk polarinst. temakari is. 58 pp. dallmeyer, r. d., peucat, j. j., hirajima. t . & ohta. y. 1990: tectono-thermal chronology within a blueschist-eclogite complex, west-central spitsbergen. svalbard: evidence from 40ar/39ar and rb/sr mineral ages. lithos 24. 291-304. gavrilenko, b. v., balasov, ju. a,. teben’kov. a . m. & larionov. a . n. 1993: u-pb ranneproterozojskij vozrast “reliktovogo” cirkona iz vysokokalievych kvarcevych porfirov zemli vedel’-jarlsberga j u z spicbergena (u-pb early pro terozoic age of “relict” zircon from high potassium quartzose porphyries of wedel-jarlsberg land, sw spitsbergen). geo chimija i, 154-158. harland. w. b. 1978: a reconsideration of late precambrian stratigraphy of southern spitsbergen. polurforsch. 48,44-61. harland, w. b . , hambrey, m. l. & waddams, p. 1993: ven dian geology of svalbard. norsk polarinst. skr. 193. 150 pp. hauser, e . c. 1982: tectonic evolution of a segment of the west spitsbergen fold belt in northern wedeljarlsherg land. ph.d. thesis. university of wisconsin. 188 pp. hoel, a . 1918: rapport preliminare de i’expedition nor vegienne de 1918 au spitsberg. geogr. 32. 231-235. irvine, t. n. & baragar, w. r . a . 1971: a guide to the chemical classification of the common volcanic rocks. can. 1. earth sci. 8 , 52s548. krasil’seikov, a. a . & kovaleva, g. a. 1979: precambrian rock-stratigraphic units of the west coast of spitsbergen. pp. 81-88 in winsnes, t. s. (ed.): the geological development of svalbard during the precambrian, lower palaeozoic, and 302 'ju. a . balasou et al. devonian norsk polarinstitutt symposium on svalbards geology. oslo. 2-5 june 1975. skr. 167. krasnobaev. a . a . 1985: morfologifeskie i geochimiceskie svojstva poligenetifeskich cirkonov (morphological and geo chemical properties of polygenetic zircons. pp. 30-55 in cajkovskij v. k. ( e d . ) : geologiteskoe izufenie dokembrija akcessornymi mineralami (geological study of the pre cambrian by means of accessory minerals). nauka. moscow. kretz. r . 1983: symbols for rock-forming minerals. a m . mineral. 68. 277-279 krogh, t . e. 1973: a low-contamination method for hydro thermal dissolution of zircons and extraction of u and pb for isotopic age determinations geochem. cosmochem. acta37, 48s494. ludwig, k. r . 1991a: pbdat-a computer program for pro cessing pb-u-th isotope data. version 1-20, u.s.g.s. open file reporr. 88-542. ludwig. k r . 1991b: a plotting and regression program for isotope data. version 2-56. u.s.g.s. open file report. 91 145 lundberg. b . & smellie. j . a . t 1979: painorova and mer tainen iron ores two dcposits of the kiruna iron ore type in northern sweden. econ geol 74. 1137-1152. magnusson. n h . 1y70: the origin of the iron ores in central sweden and the history of their alterations. part i . suer. geol. undrrs. c'. 64.3. 127 pp. miyashiro. a . 1974: volcanic rock series in island arcs and active continental margins. a m . j . scr. 2 7 4 . 321-355. miyashiro. a . & shido, f 3975: theoleiitic and calcalkalic series in relation to the behaviors of titanium, vanadium, chromium. and nickel. am. 1. sci. 275. 265-277. ohta, y. 1994: caledonian and precambrian history in svalbard: a review, and an implication of escape tectonics. tecronophys. 231. 18s194. ohta, y., & dallmann, w. k. (eds.) 1994: geological map of svalbard 1 : 1oo.ooo, sheet b12gtorellbreen. digitalversion. orvin, a. k. 1940: outline of the geological history of spits bergen. skr. svalb. ishauet 78, 57 pp. parak, t. 1975: the origin of the kiruna iron ores. suer. geol. unders. c. 709, 209 pp. ringwood, a. e. 1974: the petrological evolution of island-arc systems. .i. geol. soc. lon. 130, 185-204. smulikowski, w. 1965: petrology and some structural data of lower metamorphic formations of the hecla hoek succession in homsund, vestspitsbergen. stud. geol. polon. 18,7-107. smulikowski, w . 1968: some petrological and structural obser vations in the hecla hoek succession between weren skioldbreen and torellbreen, vestspitsbergen. stud. geol. polon. 21, part 6 , 97-161. stacey, j . s . & kramers, j . d. 1975: approximation of ter restrial lead isotope evolution by a two-stage model. earth planet. sci. lett. 2 6 , 207-221. taylor. s. r . & mclennan. s. m. 1985: theconti,ientalcrust: its composition and evolution. blackwell scientific publications, oxford. 312 pp. teben'kov. a . n . 1984: pozdnedokembrijskie magmatiteskie formacii zapadnogo spicbergena. (late precambrian mag matic formations on west spitsbergen.) vestnik lenin gradskogo gosudarstvennogo uniuersiteta 4 ( 2 4 j . 88-93. por_011.fm polar research 26 (2007) 1 – 6 © 2007 the author 1 from the editor: evolves, and norway and the ipypolar research doi:10.1111/j.1751-8369.2007.00011.x march marks the start of the international polar year (ipy) and i am very pleased to announce on this occasion that we’ve joined hands with blackwell publishing, which will henceforth publish the journal while editorial control remains with the editorial office at the norwegian polar institute (npi). blackwell, whose roots in oxford extend back for a century, specializes in partnerships with learned societies and research institutions such as our own. the services provided by our skilled and experienced publishing team at blackwell will benefit polar research ’s readers and contributors in a variety of ways. for example, the complete contents of the journal are accessible online to subscribers via its new website at www.blackwell-synergy.com. non-subscribers can access abstracts and can be directed to articles containing the search words that interest them. contributors will soon submit their work online. accepted, copyedited manuscripts will be made available online, potentially well in advance of print publication. in addition, authors of accepted manuscripts have the option of paying to make their articles freely accessible to all internet readers. to find out more, please see the new journal new homepage at www.blackwellpublishing.com/por. another important change for polar research is the establishment of an editorial board and a larger panel of editorial advisors. the journal remains grounded in the npi, but its horizons have been considerably broadened by bringing together this international group of distinguished polar scientists. i welcome them on board and look forward to our working together to represent the best of polar science in the pages of polar research . with the increasingly widespread recognition that the arctic and antarctic regions are profoundly significant for the earth’s climate, ecosystems and, ultimately, human society, polar studies are a tremendously exciting and important field of science today. under the auspices of the international council of science and the world meteorological organization, the ipy is a major international initiative aiming to amass a broad range of data that will elucidate the current state of both polar regions, as well as shed light on their history. more than 60 nations and at least 50 000 scientists and technicians will be involved. previous initiatives—in 1882–83, 1932–33 and 1957–58—have had deep impacts on our understanding of polar processes and their roles in global processes. however, many important aspects remain poorly understood. climate change has become one of the major issues facing humankind. it has become clear that the polar regions are quite sensitive to climate change, and it is increasingly understood that the polar regions play a fundamental role in the global climate. during the last 20 years, parts of the antarctic peninsula, siberia and alaska have been warming up more rapidly than any other areas on earth. we have witnessed the break-up of antarctic ice shelves and there has been a great deal of discussion about the ice cover of the arctic ocean—whether it is disappearing and what this could mean for the global climate. to try to understand the present-day global climate and to develop climate models that can accurately predict the changes that the future holds in store, scientists require an improved picture of current conditions and their role in influencing the oceans, the atmosphere and land masses. this will be a major theme in this ipy. another important facet of the current ipy is the inclusion of social science for the first time: how are people being impacted by the changes in the polar regions? education and outreach are also receiving special emphasis so that the ipy will raise the general understanding of the significance of the polar regions, particularly among young people—the scientists and decision-makers of tomorrow. a nation with a foot in both polar regions, norway will be prominently represented in the research activities of the ipy. norwegian proposals that were endorsed by the international ipy joint committee were then considered for funding by the research council of norway. after careful evaluation, 10 of the norwegian-led cluster projects that had received the joint committee’s endorsement subsequently received funding from the research council. an additional 16 norwegian projects were funded by the council, bringing the total to 26 projects (table 1). the council has granted funds specially earmarked for ipy research amounting to about 290 million nok (about 36 million euro or 47 million usd) to these projects. additional financing is being allocated from other money at the research council’s disposal, as well as from funds such as those regularly dedicated to the norwegian antarctic research expeditions, so that the total number of norwegian ipy projects being funded is about 30. for a nation with a population of about 4 million this constitutes a considerable investment of money and expertise. scientists at the npi are participating in a variety of national and international projects (table 1), including several projects that the institute is leading. one npi 2 polar research 26 (2007) 1 – 6 © 2007 the author from the editor project, headed by oceanographer vladimir pavlov, will create a norwegian–russian historical sea level data set and will analyse a broad range of environmental parameters, such as river run-off, glacier volume and precipitation, in order to identify the major factors affecting sea level variability in the nordic seas at different timescales. these data will contribute to a conceptual model that will be used, in combination with climate change scenarios, to generate predictions about future sea level variability in the region. the international project led by npi biologist kit m. kovacs will deploy satellite relay data loggers that have conductivity, temperature and depth sensors on deepdiving marine mammals in the arctic and antarctica to investigate their movement patterns, behaviour and habitat utilization. the equipment, which is glued to the fur of the animals, will yield abundant high-precision oceanographic data sets that would not be obtainable in other ways. these data will contribute to oceanographic and climatic modelling projects, as well as providing information about habitat use by seals. reciprocal, extensive collaboration with other ipy research endeavours will provide this project with comprehensive oceanographic coverage that will permit novel quantification of factors that determine habitat selection by key polar marine mammal species. the 10 member countries within the meop (marine mammals exploring the oceans pole to pole) consortium will deploy tags on hooded and harp seals in the arctic and southern elephant, crabeater and weddell seals in the antarctic. marrying classical oceanography with marine mammal ecology, this innovative project promises to significantly advance our understanding of the world’s oceans and some of the top predators that inhabit them. another npi project monitors the impacts of oil and gas extraction on the traditional lands of the indigenous people of the nenets autonomous okrug (nao) in north-western russia. the project is led by geologist winfried dallmann, who is collaborating with vladislav peskov of the nenets association yasavey. intensive oil and gas industry developments in the nao have made significant impacts on the environment and the socioeconomic situation of the indigenous peoples—mainly nenets and izhma-komi—who continue traditional subsistence practices, particularly reindeer-herding. laws aimed at giving indigenous peoples and the environment upon which they depend some measure of protection against the effects of oil and gas extraction have not been implemented. the project aims to keep a close watch on the situation and to collect a wide array of information in a geographic information system database. the data will be accessible on the internet via an interactive map and will be presented in both english and russian. npi biologist geir wing gabrielsen is serving as co-principal investigator for an international multidisciplinary project that will investigate man-made contaminants in polar marine ecosystems, in order to better predict how higher trophic levels will be affected by the norwegian logo for the international polar year. a tagged southern elephant seal. (photo by martin biuw, sea mammal research unit, university of st andrews, st andrews, uk.) from the editor polar research 26 (2007) 1 – 6 © 2007 the author 3 table 1 the 26 norwegian ipy projects being funded through the research council of norway. a number of these projects are components of larger international initiatives with other nations assuming top leadership of the consortia. for example, the antarctic traverses being undertaken by the norwegian polar institute are part of an umbrella programme, taste-idea, coordinated by the alfred wegener institute for polar and marine research, in germany. in such cases, only the leadership of the norwegian segment is noted in the table. nearly all of the projects listed below include the participation of several institutions (only the leading institution is named in the table). projects that include the participation of norwegian polar institute researchers other than in a leading role are indicated with an asterisk after the name of the project. international consortia that are being led by norwegian institutions are indicated in boldface. project norwegian institution either leading the project or leading the norwegian component of the international consortium the norwegian contribution to taste-idea (trans-antarctic scientific traverses expeditions—ice divide of east antarctica): the norwegian–us ipy antarctic traverse norwegian polar institute iaoos (integrated arctic ocean observing system)–norway: closing the loop* norwegian meteorological institute bipolar atlantic thermohaline circulation * faculty of mathematical and natural sciences, university of bergen polar study, using aircraft, remote sensing, surface measurements and models, of climate, chemistry, aerosols, and transport norwegian institute for air research the dynamic response of arctic glaciers to global warming: the norwegian contribution to glaciodyn* faculty of mathematical and natural sciences, university of oslo thorpex (the hemispheric observing system and predictability experiment)–ipy: improved forecasting of adverse weather in the arctic region—present and future * faculty of mathematical and natural sciences, university of oslo the dynamic continental margin between the mid-atlantic-ridge system (mohns ridge, knipovich ridge) and the bear island region norsar (norwegian seismic array) continuous seismic reflection profiling buoys: a future direction for marine geophysical exploration of the arctic ocean faculty of mathematical and natural sciences, university of bergen permafrost observatory project–thermal state of permafrost: the norwegian contribution university centre in svalbard norwegian component of ecosystem studies of subarctic and arctic regions * institute of marine research pps arctic norway: the norwegian contribution to pps arctic (present-day processes, past changes, and spatiotemporal variability of biotic, abiotic and socio-environmental conditions and resource components along and across the arctic delimitation zone) norwegian institute for nature research copol (contaminants in polar regions: dynamic range of contaminants in polar marine ecosystems) a norwegian polar institute doc (dissolved organic compound) turnover in polar microbial food webs faculty of mathematical and natural sciences, university of bergen antarctic krill and ecosystem studies institute of marine research mapping threats to arctic bird populations: the effect of infectious organisms and pollution on bird health* norwegian institute for nature research arctic predators as indicators of tundra ecosystem state: the norwegian contribution to arcticwolves (arctic wildlife observatories linking vulnerable ecosystems)* faculty of science, university of tromsø marine mammals exploring the oceans pole to pole norwegian polar institute polar bear circumpolar health assessment in relation to toxicants and climate change* faculty of natural sciences and technology, norwegian university of science and technology ice age development and human settlement in northern eurasia faculty of mathematical and natural sciences, university of bergen arctic natural climate and environmental changes and human adaptation: from science to public awareness* norwegian geological survey reindeer herders vulnerability network study: reindeer pastoralism in a changing climate saami university college monitoring of development of traditional indigenous land use areas of the nenets autonomous okrug nw russia norwegian polar institute impacts of oil and gas activity on peoples in the arctic using a multiple securities perspective* faculty of social science, university of tromsø long-term sea level variability in the nordic seas norwegian polar institute community adaptation and vulnerability in the arctic regions: focus on northern norway and northern russia center for international climate and environmental research— oslo the linguistic and cultural heritage electronic network dept. of linguistics and scandinavian studies, university of oslo a this project is being co-led by the dept. of fisheries and wildlife, oregon state university. 4 polar research 26 (2007) 1 – 6 © 2007 the author from the editor at nearly 79 ° n, the research community of nyålesund, viewed from kongsfjorden, in svalbard. (photo geir wing gabrielsen, courtesy of the norwegian polar institute picture library.) an oil installation in the tundra, nenets autonomous okrug, russia. (photo courtesy of the nenets association yasavey.) changes to marine food webs brought on by climate change. many of the contaminants, such as organochlorines, carried by air and sea currents from distant human population centres pose a health risk to the organisms that end up ingesting them, particularly further up the food chain, as the contaminants become increasingly concentrated in the tissues of animals at each level. researchers will examine routes of contaminant transport to the polar regions, and how contaminants are taken up into the food web once there, and will address questions relating to how global warming and other climate changes could affect the situation. field studies will be carried out at numerous marine and terrestrial sites in the arctic and antarctic regions, including kongsfjorden and ny-ålesund, svalbard. leading a pair of traverses in antarctica, the director of the npi, jan-gunnar winther, heads the norwegian contribution to a very large-scale international programme that will involve, altogether, seven traverses across the continent. on the first leg of the norwegian–usa traverse, the team will travel from npi’s research station troll, in dronning maud land, to the south pole, a journey of some 3000 km. the return trip will take a different, somewhat shorter route (ca. 2500 km). along the from the editor polar research 26 (2007) 1 – 6 © 2007 the author 5 way, scientists and technicians will gather diverse data to build up a picture of snow, ice, atmospheric and weather conditions in dronning maud land, including some of the least-known parts of the continent. the team will deploy automatic weather stations that will provide meteorological data via satellite for several years to come. radiation will be measured using unmanned aircraft and ground penetrating radar will be used to investigate the ice sheet. the researchers will pass over areas where sub-glacial lakes have recently been discovered, and will collect snow samples for later chemical and physical analyses in laboratories in the usa and norway. the ultimate goal, toward which a number of coordinated, complementary national projects will simultaneously contribute, is to forge a better understanding of the role of antarctica in the global climate, and how changes in the ice mass balance of the continent may affect sea levels. involving four tracked vehicles pulling eight sledges loaded with residential and work-space containers, equipment and fuel, and taking place in extremely cold and probably difficult weather, this will be the most logistically challenging project that norway has undertaken in antarctica. in the next issue of polar research , polar historian stian bones will present a historical review of norway’s involvement in past ipys. from the comparatively troll research station, the base of the norwegian polar institute in dronning maud land, antarctica. (photo by andrea taurisano, courtesy of the norwegian polar institute picture library.) sverdrup research station, the norwegian polar institute’s base in ny-ålesund. (photo by helle goldman, courtesy of the norwegian polar institute picture library.) 6 polar research 26 (2007) 1 – 6 © 2007 the author from the editor modest—although nonetheless groundbreaking— endeavours of the first ipy in the late 19th century, these initiatives have evolved into highly international collaborative efforts in which multiple countries (and different institutions within them) combine forces to carry out extremely complex and ambitious projects. in a world that sometimes seems dominated by strife, this level of scientific cooperation is heartening. the current ipy has an enormous potential for bettering our understanding of polar and global systems, and to help us address some of the most pressing environmental issues and scientific questions of our time. as a final note i would like to point out that we at polar research have been happy to agree to participate in the proposed ipy project popularization of northern scholarly articles for public interest. should it find funding, the project will make scholarly writing about the north more accessible to the general public. easy-to-read synopses (more in-depth than abstracts) of selected articles from several northern-related journals will be made available on the website of the arctic institute of north america, giving non-specialists a place to go for solid, complex information presented in a readily comprehensible manner. the project is the initiative of dawn johnston, at the arctic institute of north america, and karen mccullough, editor of the journal arctic . helle v. goldman chief editor summer diet of seabirds from the frans josef land archipelago, russian arctic jan m. weslawski, lech stempniewicz and kiryl galaktionov weslawski, j . m . , stempniewicz, l. & galaktionov, k. 1994: summer diet of seabirds from the frans food samples from 102 seabirds from eight species (fulmar fulmarus glacialis. common eider somateria mollissima, glaucous gull larus hyperboreus, kittiwake rissa tridoctyla, arctic tern sterna paradisaea, briinnichs guillemot uria lomvia, black guillemot cepphus grylle, little auk alle alle) were collected during the period august 1991-1993 in the southern part of the frans josef land archipelago, w n , 53"e. the pelagic amphipod parathemisto libellula and polar cod boreogadus saida were the two most commonly taken food items (frequency of occurrence over 50% and weight contribution more than 70%). ice associated crustaceans contributed to some 10% of the weight in the samples. in general, the food composition was very similar to that reported from svalbard. however, birds from frans josef land fed on a lower diversity of prey compared to svalbard populations. jan m. wptawski, institute of oceanology, polish academy of sciences, powstaricdw warsrawy s.5, 91-967 sopot, poland; lech stempnie#icz, department of vertebrate ecology and zoology, university of gdatisk, legionow 9, 80-441 gdarisk, poland; kiryl galaktionov, murmansk marine biological institute, russian academy of sciences, vladimirskaja 17, 183023 murmansk, russia. n josef land archipelago, russin arctic. polar research 13(2), 173-181. ''*polar\ns''. introduction the frans josef land archipelago belongs to one of the least known areas in the european arctic with regard to marine ecology. it was only recently that internationally organised expeditions (russian/norwegian/polish) col lected a sizeable amount of data on the marine mammal, bird and invertebrate fauna of frans josef land (gjertz & meirkved 1992, 1993). seabirds as consumers constitute an important component of the arctic ecosystem (croxall 1987). the number of seabirds breeding and feed ing in the area provides reliable data on marine food supplies which can be used for comparisons between different regions and different years in the same area (cairns 1987; furness & nettleship 1991). in the neighbouring svalbard archipelago, this topic has been studied by hartley & fisher (1936), lydersen et al. (1989), stempniewicz & weslawski (1992), and mehlum & gabrielsen (1993). there is a lack of such data from frans josef land, with the exception of old and rather anecdotal reports by gorbunov (1932), demme (1934) and weslawski & skakuj (1992). the present paper describes the summer diet of seabirds from this area. the paper also presents possible differences between feeding of the same seabird species in two european arctic regions, svalbard and frans josef land archipelagoes. the regions are geographically close, but different as to climatic, hydrographic and ecological con ditions (weslawski 1993). in general, svalbard is exposed to the strong influence of the warm west spitsbergen current, while frans josef land is situated in the high arctic zone covered year round with drifting ice. for this reason differences in seabirds feeding are expected. material and methods during three consecutive summer seasons (august 1991,1992,1993) joint russian, norwe gian and polish expeditions worked in the area of hooker island and the neighbouring islands of the southern-central part of frans josef land archipelago (fig. 1). seabirds were col lected in the vicinity of the colony at rubini rock, hooker island. the same samples were used for analysis of chemical pollutants and parasites (matishov 1993) as well as for morphometry and the study of food content. a total of 102 speci mens from eight seabird species (fulmar fulmarus glacialis, common eider somateria mollissima, glaucous gull larus hyperboreus, kittiwake rissa tridactyla, arctic tern sternapardisaea, briinnich's guillemot uria lomoia, black guillemot cepphus 174 jan m . wplawski et al. grylle, little auk alle alle) were examined. all food samples from a given seabird species col lected in different seasons of the study were pooled because of low sample size. birds were dissected immediately after being shot. oesophagus and stomach contents were pre served in a 4% formaldehyde solution and ana lysed two months later in the laboratory. in the case of the little auks, the contents of the gular pouches were also used as food samples. each sample was washed on 0.5 mm mesh size screen and analysed under stereo microscope. the material was sorted and then identified t o the lowest possible taxonomic level. the number, length and weight of all identifiable food items were noted. standard deviation was calculated only for mean length values of the most numerous food items. in instances where only fragments of prey items were found (fish otoliths, polychaete jaws, crustacean rostra, etc.), the original lengths and weights were calculated from the formulas presented by berestovskij et al. (1989), brad street (1980), and lydersen et al. (1989). the number of fish and polychaetes ingested was esti mated as half the number of otoliths and jaws found in the samples. calorific values of fresh, not fragmented specimens of all prey taxa were measured according to the method described in szaniawska & wolowicz (1986). the following coefficients were used to present the results of the analyses of the food samples. frequency of occurrence (f%) was determined fig. 1. sketch map of the study area. the dashed area shows the mean summer ice pack range. the black dot indicates sampling locality. for each bird species as percent number of samples (stomachs) containing given prey type. also the mean number of a given food item per sample (numerical abundance) and percentage by number, weight and energy of particular prey taxa were calculated. cluster analyses were performed using the primer programme (carr 1993) (plymouth marine laboratory, uk) and the bray-curtis index of similarity, based on the frequency of occurrence matrix. empty stomachs and those containing single food item were excluded. results food content fulmar f. glacialis. remains of four prey taxa were identified in the food samples. polar cod boreogadus saida was the largest prey item (140 mm), and pelagic polychaetes were most numerous. fish (b. saida and sculpin m y o x o cephalus spp.) constituted about 85% of food weight. remains of macrophytes and plastic debris were found in each stomach. n o ice-associ ated crustaceans were identified in the fulmar diet. (table 1). common eider s . mollissima. seven prey taxa were found. all stomachs contained gastropods (margarites helicinus), constituting about 84% of the items and more than 55% of the food weight. summer diet of seabirds 175 table i . stomach contents of five seabird species and food items characterisitics. mean mean total frequency of seabird species and length wet weight number of occurrence prey items (mm) (mg) individuals f% by number by weight percentage percentage fulmaris glacialis (n = 5) polychaeta spp. margarites spp. boreogadus saida myoxocephalus scorpius pisces n.det. terrestrial plants macrophytes plastic debris somateria mollissima (n = 5 ) polychaeta spp. margarires spp. onisimus spp. gammarellus homari gammarus setosus weyprechtia pinguis boreogadus saida larus hyperboreus (n = 5 ) boreogadus saida pisces n.det. birds remains gravel sterna paradisaea (n = 5 ) polychaeta (pelagic) apherusa glacialis gammarus setosus gammarellus homari gammarus wilkitzkii pisces n.det. cepphus grylle (n = 5 ) atylrrs carinatus gammarellus homari onisimus spp. gammarus wilkitzkii parathemisto libellula lebbeus polaris boreogadus saida myoxocephalus scorpus pisces n.det. gravel 60 10 141 60 50 5 10 5 60 10 10 30 25 15 162 1 80 50 100 10 60 10 25 30 25 60 30 25 15 15 12 60 140 60 60 200 491 7,589 5,220 1 ,000 4 20 20 200 491 14 511 207 43 11,087 11,ooo 1 ,ooo 50,ooo 100 200 5 207 511 206 1 ,ooo 250 250 50 150 25 800 7.500 1 ,ooo 1 .ooo 3 1 1 1 1 1 2 1 1 31 1 1 1 1 1 2 2 5 1 1 1 3 5 2 1 1 1 1 2 1 4 8 2 2 1 60 27.3 20 9.1 20 9.1 20 9.1 20 9.1 20 9.1 40 18.2 20 9.1 20 2.7 100 83.8 20 2.7 20 2.7 20 2.7 20 2.7 20 2.7 40 20.0 40 20.0 100 50.0 20 10.0 20 7.7 20 7.7 60 23.1 100 38.5 40 15.4 20 7.7 20 4.3 20 4.3 20 4.3 40 8.7 20 4.3 40 17.4 80 34.8 20 8.7 20 8.7 20 4.3 4.0 3.3 50.7 34.9 6.7 0.0 0.3 0.1 0.7 55.8 0.1 1.9 0.8 0.2 40.6 8.0 0.7 91.2 0.0 4.2 0.1 12.9 53.3 8.6 20.9 0.4 0.4 0.1 0.4 0.0 4.7 88.1 2.9 2.9 0.0 benthic amphipods (gammarellus homari, gam marus setosus, weyprechtia pinguis, onisimus spp.) were the second in importance. ice-associ ated crustaceans were not present in the food samples (table 1). glaucous gull l. hyperboreus. remains of juv enile birds were found in each stomach. they included brunnich’s guillemots, kittiwakes and little auks. large polar cods (18 cm) were found in two stomachs. birds contributed to more than 90% of the energy intake (table 1). kittiwake r. tridactyla. eight prey taxa were found. the largest prey found was a 16 cm polar cod b. saida, and the smallest was a 4 m m long culanus glacialis. the most common food items were amphipoda (apherusa glacialis 46% and parathemisto libellula 32% of all items). polar cod of mean length 13 cm was the most important food component. it constituted about 90% of food weight and energy intake. ice-associated crustaceans contributed to only 4% of energy intake (table 2). ta bl e 2. s to m ac h co nt en ts in t he k itt iw ak e r is sa m 'd nc ry lo ( n = 1 9) a nd f oo d ite m s ch ar ac te ri st ic s. m ea n (s d) m ea n t ot al e ne rg et ic fr eq ue nc y of m ea n le ng th w et w ei gh t nu m be r of va lu e oc cu rr en ce nu m be r of p er ce nt ag e pe rc en ta ge pe rc en ta ge pr ey i te m (m m ) ( w ) in di vi du al s (k j/ gd w ) f % in di vi du al s by n um be r by w ei gh t by e ne rg y p ol yc ha et a s q q . (p el ag ic ) c al an us s q q . a p h ew a g la ci al is g am m ar us w if ki tz k ii pa ra th em is to l ib el lu la m eg an yc tip ha ne s no rv eg ic a b or eo ga du s sa id a m yo xo ce ph aa lu s sc or pi us te rr es tr ia l p la nt s m ac ro ph yt es 60 .0 (-) 25 .0 (-) 7. 0 (1 .0 9) 6. 4 (1 .3 5) 10 .8 ( 2. 14 ) 13 3. 1 (1 9. 90 ) 30 .0 (-) 60 .0 () 5. 0 (-) 10 .0 (-) 20 0 7 2 20 7 13 27 0 5 . ooo 5, 22 0 4 20 5 19 .7 43 26 .0 29 7 19 .7 55 16 .0 20 8 16 .7 4 22 .0 30 24 .2 1 22 .0 1 1 19 .7 16 16 22 16 84 16 58 5 5 5 0. 5 3. 9 27 .0 5. 0 18 .9 0. 4 2. 7 0. 1 0. 1 0. 1 0. 8 6. 7 46 .0 8. 5 32 .2 0. 6 4. 7 0. 2 0. 2 0. 2 ta bl e 3 . st om ac h co nt en ts in th e b ru nn ic h' s g ui lle m ot u ri a lo m ui a (n = 1 1) a nd f oo d it em s ch ar ac te ri st ic s. 0. 4 0. 3 0. 1 0. 1 0. 3 0. 1 5. 0 3. 9 1. 6 0. 9 0. 5 0. 4 89 .8 92 .1 2. 3 2. 1 0. 0 0. 0 0. 0 pr ey i te m m ea n (s d) m ea n to ta l e ne rg et ic fr eq ue nc y of m ea n le ng th w et w ei gh t nu m be r of va lu e o cc ur re nc e nu mb er o f p er ce nt ag e pe rc en ta ge pe rc en ta ge (-) (m g) in di vi du al s (k j/ g dw ) f% in di vi du al s by n um be r by w ei gh t by e ne rg y po ly ch ae ta s q p . ( pe la gi c o ni si m us s q q . r ha ch ot ro pi s ac ul ea ta g a m m a m w ilk itz ki i g am m an cr s et os us pa ra th em is to l ib el lu la th ys an oe ss a in er m is b or eo ga du s sa id a pi sc es n .d et . gr av el 60 .0 (-) 10 .0 (-) 25 .0 (-) 25 .0 (-) 8. 0 (-) 14 .5 ( 2. 43 ) 15 0. 7 (2 1. 86 ) 25 .0 (-) 50 .0 (-) 10 .0 (-) 20 0 14 8 20 7 20 7 48 15 6 10 ,o oo 1 , o oo 10 0 2 2 1 9 3 15 6 28 22 2 2 18 .0 18 .0 16 .0 16 .0 16 .0 16 .7 22 .0 24 .2 24 .2 18 0. 2 18 0. 2 9 0. 1 54 0. 8 18 0. 3 92 14 .2 9 2. 5 54 2. 0 18 0. 2 18 0. 2 0. 9 0. 9 0. 4 4. 0 1. 3 68 .7 12 .3 9. 7 0. 9 0. 9 0. 2 0. 0 0. 0 0. 8 0. 3 3. 0 1. 9 92 .8 0. 9 0. 1 0. 1 0. 0 0. 0 0. 6 0. 2 1. 7 1. 4 94 .9 0. 9 0. 0 3 3 s g c w g 5 k p " summer diet of seabirds 177 arctic tern sterna paradisaea. six food taxa were identified. an unidentified fish of ca. 10 cm length was the largest prey item. gammarid crus taceans ( g . homari, g . setosus, gammarus wil kitzkii) were the most numerous and contributed to more than 70% of the food weight. nearly 10% of the food mass was formed by ice-associated crustaceans (table 1). briinnich's guillemot uria lomvia. nine prey taxa were found. the smallest was an 8 mm long amphipod (rhachtropis aculeata) and the largest was 16cm long polar cod. p. libellula was the most numerous prey constituting about 69% of the items. polar cod was the main food item both as to weight (93%) and energy value (95%). ice associated crustaceans were of negigible import ance and constituted less than 1% of prey weight and energy (table 3). black guillemot cepphus grylle. -eight food taxa were identified. polar cod (16cm long) was the largest prey item. fish were most important, both in number (nearly 45% of items), and in food weight (90%). decapods and gammarids contri buted to less than 10% of the food intake (table 1). little auk alle alle. thirteen prey taxa were identified (table 4). the largest food item was the snail fish liparis spp. of ca. 60mm length found in one stomach only. the smallest items were 3 mm long ostracoda. the most numerous taxon was c. glacialis represented both by sub adult (copepodit iv and v) and adult specimens of 6 to 8 mm long. they constituted 84% of the total number of prey items, and 72% of the food weight. the second most important prey was thy sanoessa inermis (about 11% of weight and energy value). ice-associated amphipoda (a. glacialis and g . wilkitzkii) contributed to more than 12% of energy intake, while 73% was provided by copepods (table 4). food selection and competition some distinct differences in the size class dis tribution of most common zooplankters occurring in frans josef land surface waters (koszteyn & kwaceniewski 1992) and in the collected food samples were found. the largest specimens of c. glacialis (6-10 mm), the middle sized specimens of p. libellula and the lower mean fraction of a . glacialis were chosen by feeding seabirds. in general, only food items 6 mm long or bigger were selected. smaller preys constituted less than 7% of total number of items ingested by birds studied. 178 jan m . wgsiawski et al. 10 bray curtis simllarlty -l 8 8 8 2 8 8 g g s s o 1 : : : : : : : : : 1 i fig. 3. length frequency of all prey items taken by the black guillemot 1 brunnich’s glaucous gull fig. 2. the dietary overlap-cluster of prey similarity cluster analysis of seabird diet similarity shows closely related diets of the kittiwake, briinnich’s and black guillemots, all relied mainly o n polar cod and p. libellula. it appears also that on frans josef land eiders and arctic terns exploit similar food resources (gammarid amphipods). the little auks took mainly calanus (70% of food weight and energy) and were separated from other sea birds as well as the glaucous gulls occupying the distant niche of carnivore and scavenger (fig. 2). among the three most numerous seabirds com pared, the little auks took the smallest, kittiwakes the medium sized, and briinnich’s guillemots the largest prey items (fig. 3; tables 3, 4). in our study seabirds utilising similar food resources (large dietary overlap) preferred different length classes of the same prey. because of small samples only size of the most common prey items of the kittiwakes and briinnich’s guillemots (a pair of species with considerable dietary overlap) were compared. briinnich’s guillemots took signifi cantly larger polar cods (t = 3.02, df = 50, p < 0.005) and p. libellula (t = 15.60, df = 362, p < 0.001) than the kittiwakes. polar cod was the only prey item used by nearly all investigated birds. it contributed t o more than 90% of energy intake in the diets of four most numerous seabirds. p. libellula was second of importance with regard to the frequency of occur length classes in (mm) 60 80 110 140 170 % 0 2 4 6 8 i 0 12 14 16 18 20 22 24 26 28 30 little auk 10 0 2 4 6 8 i 0 12 14 16 18 20 22 24 26 28 30 60 80 110 140170 frans josef land. summer diet of seabirds 179 them use a wide food range, like the glaucous gull feeding on marine invertebrates, fish, eggs, birds, carrion and offal, in varying proportions depend ing on local and seasonal availability (stempnie wicz & weslawski 1992). eiders are less opportunistic and feed on benthic amphipods and thin-shelled gastropods throughout their dis tribution area in the european arctic, but usually take locally abundant species of preys (hartley & fisher 1936; uspenskij 1979; lydersen et al. 1989; mehlum 1989). food specialists such as the little auk, use a very narrow feeding niche limited basically to zooplankton. however, even the little auk diet may vary considerably in different areas and seasons. in spring their diet consists mainly of calanoid copepods while in august they take first of all amphipods (parathemisto sp., a. gla cialis) and the polar cod (bradstreet & cross 1982; lydersen et al. 1989; mehlum & gabrielsen 1993). the relatively low diversity of high arctic pel agic ecosystems results in somewhat artificial simi larity of seabird diet in different arctic regions. the polar cod and p. libellula, the most important food components of frans josef land seabirds, are also reported as main food preys in svalbard (lydersen et al. 1989; mehlum & gabrielsen 1993) and in the canadian arctic (bradstreet 1980). some differences in seabird diets in the two, geographically very close areas (frans josef land and svalbard) may be a result of some distinct differences between these areas concerning cli mate and hydrology, which influence the com position of the marine fauna. pack ice arrives scarcely in the svalbard waters during the summer and stays far from the western coast where the majority of seabird colonies are situated. in frans josef land waters pack ice is present throughout the year. the coastal ice-covered waters of frans josef land are apparently rich in pelagic crus tacean resources, contributed t o by sympagic fauna (estimated by gulliksen & lonne 1991 to 1-10 g/m3), neritic plankton (decapoda larvae, amphipods 0.5g/m3; own data) and marine plankton (copepods l g / m 3 ; own data). ice associated fauna contributed to some 20% of seabirds' food in frans josef land. mehlum & gabrielsen (1993) report a similar number for ice covered waters in the northern barents sea. in the canadian arctic, close t o the fast ice edge, sympagic species contribute to ca. 10% of seabirds' diet (bradstreet & cross 1982). rence in birds stomachs, but did not contribute significantly to the total energy consumption. discussion optimal foraging theory (stephens & krebs 1986) predicts minimising foraging costs (in case of sea birds the costs of flights to feeding grounds, prey location, choice, pursuit, etc.), and maximising energy gains (energy income as a result of feeding). during the breeding period the seabirds should therefore exploit the feeding grounds situ ated close to colony, offering abundant prey, easy to locate and catch. to obtain more energy during one feeding trip the birds would have to choose sites with high available prey density and food items of maximal size in relation t o their carrying capacity. the longer the distance between the colony and the feeding grounds the bigger food loaj is more profitable (croxall 1987). larger prey taxa (b. saida, g. wilkitzkii, p. inermis) usually constituted the higher proportion of summer diets of the same seabirds in frans josef land (tables 2, 3, 4) than in svalbard (mehlum & gabrielsen 1993). in addition. selecting bigger prey species within the same genera (c. glacialis versus c . finmarchicus, and p . libellula versus t. abyssorum; weslawski & skakuj 1992) could result in larger average size of food items in frans josef land seabirds. how ever, considefable. local and seasonal variability in diets demonstrated by mehlum & gabrielsen (1993) for svalbard seabirds as well as small sample size in this study make the above state ment uncertain. o n the other hand however, mean individual size of p. libellula taken by frans josef land seabirds was smaller compared to svalbard (mehlum & gabrielsen 1993). that may reflect the peripheral character of p. libellula population in west spitsbergen, where adult, large size classes are more frequent. in frans josef land, at the centre of population occurrence (koszteyn et al. in press) more even size frequency may be observed, so more accessible and common are middle sized individuals. no differences were found in mean size of polar cod taken by seabirds from svalbard and frans josef land. that may indicate similar distribution of class sizes in polar cod populations in both areas compared. seabirds are opportunistic within the food spec trum they are morphologically, physiologically and behaviourally adapted to exploit. some of 180 jan m. wgsiawski et al. the number of food taxa (zooplankton and fish) recorded in the summer diets of seabirds is considerably lower in frans josef land than at svalbard. in total, the same three most numerous seabird species (little auk, briinnich’s guillemot and kittiwake) take 19 prey taxa in frans josef land and at least 36 in svalbard waters. ten species of fish were found in the food samples from svalbard and only three from frans josef land. the latter did not contain representatives of such important groups of marine invertebrates as gastropods, cephalopods, decapods and chaetognaths (hartley & fisher 1936; mehlum & gabrielsen 1993; this study). lower sample size in this study may partly be responsible for that. compared to the study by dernme (1934) on frans josef land seabirds of the same species, our data are stikingly different. demme (1934) recorded very few polar cod and no parathemisto, but she found the hyperbenthic gammarid atylus carinatus as predominating in the food sample collection of over 150 seabirds from hooker island. difference in methods (not described in demme’s paper) might be partly responsible for this discrepancy, otherwise the interpretation is difficult. we may consider all common, subsurface living animals of 5 to 200 mm length as potential prey taxa for seabirds. there are at least 50 such species in svalbard waters and no more than 30 in frans josef land (wesiawski et al. 1994), so one might expect a larger overlap in diet and increased inter specific competition among seabirds in frans josef land. in the situation common on frans josef land, however, when the potential prey is brought up to the surface, pushed into shallow shore water, closely associated with ice, etc., i.e. it aggregates in a natural or extorted way in the sites easily accessible for birds, different seabird species can then feed on the same food resources. this does not involve an increase of the inter specific competition because food resources are usually superabundant in such places. in other words different seabirds exploit the same feeding niche despite that normally they separate their feeding grounds by zones (e.g. inshore feeding black guillemot and offshore feeding briinnich’s guillemot) or by layers (e.g. surface feeding kit tiwake, subsurface feeding little auk and bottom feeding black guillemot). patchy distribution of zooplankton in the sea makes location of prey aggregations by feeding indication which the birds can perceive, making location easier. the presence of pack ice may be one such indicator (the sympagic fauna constitutes about 20% of the diet). birds may use pack ice as an aid in finding at least one fifth of their food. the remaining prey can also be found in such places, which are not, however, closely associated with ice floes. franz josef land is situated further north and east than svalbard and pack ice occurs there permanently in the sounds between the islands throughout the year. during the breeding season seabirds can find abundant and easily available food close to the colony. our observations show that the majority of seabirds nesting on rubini rock forage in the mellenius sound, i.e. a few km from the colony. the specific hydrological situation in the sounds (strong tidal currents, upwellings, whirl-pools, etc.) concentrate the food and favour the seabirds feeding there. for instance, mass presence of half-dead pelagic invertebrates pushed by tidal currents into the shallow water along the shore-line was very often observed during our field work. they were exploited extensively by the kittiwakes. in west ern spitsbergen however, the large colonies are often situated in the fjords (norderhaug et al. 1977) and seabirds usually fly some tens of km to their feeding grounds in the open sea. acknowledgemenu. we would like to thank our colleagues from russian/norwegian/polish expeditions to frans josef land 1990-1992 for their help during field work. we are obliged especially to prof. g. g. matishov, director of murmansk marine biology institute, and to dr thor larsen from norweg ian polar institute, who made the expeditions possible. a. szaniawska kindly measured calorific values of all prey taxa. thanks also to plymouth marine laboratory who generously offered to our project the primer package. financial support was received from the university of gdadsk (grant nr. bw/ 1140-5-00872). references berestovskij, g . , anisimov. a , , denisenko, c. g., luppov, e. h . , savinov, v. s. & timofeev, s. m. 1989: pp. 1-23 in: relationships between size and body mass of some inuert ebrates and jishes of north-west atlantic. akademja nauk sssr, apatity. (in russian). bradstreet, m. s. w. 1980: thick-billed murres and black guillemots in the barrow strait area, n.w.t.. during spring: diets and food availability along ice edges. can. 1. 2001. 58, 2120-2140. bradstreet, m. s. w. & cross, w. e. 1982: trophic relation ships at high arctic ice edges. arctic 35. 1-12. cairns, d . k. 1987: seabirds as indicators of marine food birds difficult. a key question is a presence of any supplies. biol. oceanogr. 5, 261-271. summer diet of seabirds 181 croxall, j. p. 1987: seabirds feeding ecology and role in marine ecosystems. cambridge, cambridge univ. press. carr, m. r. (ed.) 1993: user guide to primer, v. 3.1. plymouth routines in multivariate ecological research. plymouth marine laboratory, uk. demme. n. p. 1934: birds’ bazaar on the rubini rock (hooker island, franz joseph land). trudy arkt. inst. 11, 55-86 (in russian). furness, r . w . & nettleship, d. n. 1991: seabirds as monitors of changing marine environment. acfa x x congr. int. omith., 2237-2279. gjertz. 1. & morkved. b . (eds.) 1992 environmental studies from frans josef land, with emphasis on tikhaia bay, hooker island. norsk polarinst. medd. 120, 1-130. gjertz, 1. & morkved, b. (eds.) 1993: results from scientific cruises to frans josef land. norsk polarinst. medd. 126. 1 30. gorbunov, g . p. 1932: birds of franz joseph land. trudy arkt. i n s t . 4 , 1-234 (in russian). gulliksen, b. & lonne, 0. j . 1991: sea ice macrofauna in the antarctic and the arctic. j . mar. syst. 2, 53-61, hartley, c. h. & fisher, j. 1936: the marine foods of birds in an inland fjord region in west spitsbergen. part 2. birds. 1. anim. ecol. 5. 370-389. koszteyn, j. & kwasniewski, s. 1992: the near shore zooplank ton of the tikhaia bay (franz josef land) in august 1991. n o n k polarinst. medd. 120. 23-33. koszteyn, j., timofeev. s., wgslawski, j . m. & malinga, b. in press: size structure of parathemisto abyssorum boeck and parathemisto libellula (mandt) populations in the european arctic seas. lydersen, c h . , gjertz, 1. & weslawski, j . m. 1989: stomach contents of autumn feeding marine vertebrates from hornsund, svalbard. polar record 25, 107-114. matisov, g . g . (ed.) 1993: the results of biological research of the international biological station “calm bay” on frans josef land in 1992. russian academy of sciences, apatity. pp. 1 47. (in russian). mehlum. f. 1989: eider studies in svalbard. norsk. polarinst. skrifrer 195, 1-68. mehlum, f. & gabrielsen, g . w. 1993: the diet of high-arctic seabirds in coastal and ice-covered, pelagic areas near the svalbard archipelago. polar res. 12, 1-20. norderhaug, m., brun, e., mollen, g . u. 1977. barentshavets sjofuglressurser. norsk polarinst. medd. 104. 119 pp. sternpniewicz, l. & weslawski, j. m. 1992: outline of trophic relationships in hornsund fjord, sw spitsbergen (with special consideration of seabirds). in: opalibski, k. w. & klekow ski, r. z. (eds.): landscape. life world and man in high arctic. wanzawa, 1e pan, 271-298. stephens, d . w., krebs, j. r . 1986. foragingtheory. princeton university press, princeton, nj. szaniawska, a. & wolowicz, m. 1986: changes in the energy content of common species from hornsund, sw spitsbergen. polar res. 4 , 85-90. uspenskij, s. m. (ed.) 1979: ecology and morphology of eiders in the u s s r . nauka, moscow (in russian). wgslawski, j . m. & skakuj, m. 1992: summer feeding of seabirds in tikhaia bay, frans josef land. norsk polarinst. medd. 1 2 0 , 5 5 4 2 . wgdawski, j. m. 1993: the comparison of west spitsbergen and frans josef land marine coastal ecosystems. studia i materialy oceanologiczne (simo) 64, 331-341. wgslawski, j. m., ryg, m., smith, t. g . & oritsland, n. a. 1994: the diet and food availability of ringed seal (pusa hispida) in svalbard. arctic 47. 109-114. meinke.indd 75meinke et al.: polar research 20(1), 75–83 the arctic fox (alopex lagopus) is a small mammal weighing 2-5 kg, with circumpolar distribution. it has a home range ranging from 4 100 km2 (frafjord & prestrud 1992; anthony 1997) but several ear-tagging and radio-tracking studies have revealed that the arctic fox is capable of undertaking long-distance movements (eberhardt & hanson 1978; eberhardt et al. 1983; frafjord & prestrud 1992; russian papers referenced by fay & rausch 1992). the longest movement recorded was 2300 km (eberhardt, unpubl. data referenced by garrott & eberhardt 1987). the arctic fox inhabits the entire coastal zone of greenland and is found in two interfertile colour morphs: a blue and a white. the colour of a fox is determined by the alleles at one locus, where “the blue allele” is dominant over the recessive white one (adalsteinsson et al. 1987). based on observations and hunting statistics, hersteinsson (1989) found a positive correlation between the length of time the ground was snow-covered and the proportion of white foxes in icelandic populations. this situation had previously been noticed in greenland by braestrup (1941), who described the blue and the white fox as two subspecies: the white one subsisting on lemmings genetic differentiation of populations of greenlandic arctic fox pia g. meinke, christian m. o. kapel & peter arctander most microsatellites are very polymorphic. this makes them powerful markers for observing genetic differentiation between closely related populations. the population structure of the greenlandic arctic fox (alopex lagopus) was studied genetically by analysing six polymorphic microsatellite loci of 75 foxes from four populations in different parts of greenland. genotypes were determined at the six loci for most of the individuals. population differentiation was quantified in three different ways both within the total population and pairwise between all populations. the tests were fisher’s exact test, rho estimates and fst estimates, all of which supported a highly significant subdivision of the total population, and they showed significant differentiation in allele frequencies between all pairs of localities. it is concluded that the known long-distance migration of the greenlandic arctic fox has not resulted in complete genetic mixing of the populations. fisher’s exact test was also used to estimate levels of genetic differentiation between the two colour morphs: white and blue. no difference was found between allele frequencies of the two color morphs in any of the locations, and it was concluded that the white and blue morphs of the greenlandic arctic fox share the same habitat, at least during the mating season. p. g. meinke, dept. of evolutionary biology, copenhagen university, universitetsparken 15, dk-2100 københavn ø., denmark; c. m. o. kapel, danish center for experimental parasitology, the royal veterinary and agricultural university, bulowsvej 17, dk-1870 frederiksberg c, denmark; p. arctander, dept. of evolutionary biology, copenhagen university, universitetsparken 15, dk-2100 københavn ø., denmark. 76 genetic differentiation of populations of greenlandic arctic fox and living in the mostly snow-covered inland and the blue one depending to a large extent on products of the sea and living near the coast. braestrup ś studies, based on fur trade statistics, were continued by vibe (1967), who included field studies and climate statistics. he stated that unstable climatic periods during the last centuries, with the climate favouring the blue morph in some periods and the white one in other periods, have resulted in the “lively bastardization and creation of mixed populations which prevail nearly everywhere in coastal regions today”. braestrup (1941) found large fluctuations in the proportion of white foxes in the hunting bags from west greenland and attributed this to a massive influx of white foxes to west greenland from canada and east greenland in years with low lemming populations. in a morphological study of the foxes of greenland, the blue foxes from different districts showed significant differences in (metric) bone measures while the white ones did not (berg 1993). berg suggested that the blue colour morph is more stationary than the white, due to the food supply in coastal areas being less variable between years than in inland habitats. russian observations (reviewed by wrigley & hatch 1976) showed that foxes migrate from november to january and return in february and march to breed. if this is the case, samples collected in winter could include migrants and could therefore be misleading. the aim of the present study was to delineate the genetic relationships of four arctic fox populations and the two colour morphs of arctic fox in greenland. the following questions were put forward: 1) are geographically distant populations significantly differentiated? 2) are the two colour morphs genetically differentiated? 3) are there genetic differences between foxes sampled at the same locality during different seasons? to answer these questions we used six polymorphic microsatellite loci. due to the generally high mutation rate (10-2 10-5 mut./ locus/ generation) (weber & wong 1993), microsatellites tend to be very polymorphic, which make them powerful markers for observing the differentiation between closely related populations. however, their mutational modalities also result in a risk of homoplazy (valdes et al. 1993; weber & wong 1993) and some microsatellites might have alleles that are not detectable (null alleles) (callen et al. 1993). also, microsatellite evolution is not yet properly understood and it could be problematic to consider them as strictly neutral markers: constraints on allele size have been implicated (garza et al. 1995) and numerous indications of microsatellites involved in gene expression and function have been found (reviewed by kashi et al. 1997). furthermore, the possible effect of a selected locus on a closely linked microsatellite has been discussed (slatkin 1995a). several mutation models have been suggested to work for microsatellites. two are most used: the infinite allele model (iam) (estoup et al. 1995) and the stepwise mutation model (smm) (shriver et al. 1993; valdes et al. 1993). materials and methods samples seventy-five greenlandic arctic foxes from four widely spaced localities are included in this study; see fig. 1 for sample details. all the foxes were 80 70 60 n greenland canada søndre strømfjord (kangerlussuaq) 20 individuals 6 blue; 14 white sampled: 19 in may-aug. 1992 1 in feb. 1993 thule air base (pituffik) 16 individuals 15 blue; 1 white sampled: 8 in feb. 1992 8 in july 1992 scoresbysund (ittoqqortoormiit) 19 individuals 8 blue; 11 white all sampled oct. 1993-apr. 1994 julianehåb (qaqortoq) 20 individuals 12 blue; 8 white sampled: 7 in mar.-apr. 1992 13 in mar. 1993 400 800 0 km fig. 1. map of greenland showing sites, sizes and dates of arctic fox sampling. 77meinke et al.: polar research 20(1), 75–83 caught in traps, killed and kept frozen at –20 °c in a period of two to three months prior to sampling of muscle tissue. dna was extracted using proteinase k and phenol/chloroform-solutions (e.g. sambrook et al. 1989). the foxes analysed here have been included in studies on parasitology, diet and population composition (kapel et al. 1996; kapel & nansen 1996; kapel 1999). analyses of microsatellite loci several microsatellite loci originally described in studies of wolf and dog were screened. the primer sets designed for dog microsatellite loci turned out to give the best results, and six of them were chosen and optimized for the arctic fox: cph3, cph6, cph9, cph15, cph16, and cph18 (fredholm & winterø 1995). all six microsatellite loci used are dinucleotide repeats, and all but cph3 have perfect repeats (see fredholm & winterø 1995). the final pcr conditions were as follows (table 1): denaturation at 94 °c for 2 min., x cycles of denaturation at 94 °c for y sec., annealing at z °c for y sec. and extention at 72 °c for y sec., x, y and z are specified for each locus in table 1. the amplification quality in different pcr machines differed from locus to locus. the final choice of machines is also shown in table 1. dna was amplified in a 10 µl reaction volume (10 mm tris-hcl, 1.5 mm mgcl 2 , 50 mm kcl, ph 8.3, 200 µm of each dntp, 200 pm of each primer, and 0.025 units of boehringer-mannheim taq dna polymerase). the products were run on 4.24 % acrylamidgels on an abi 377 sequencing machine (perkin elmer) using dye-labeled primers (one primer in each primer set) and rox 500 (perkin elmer) as internal standard. genotypes were determined at the six loci for most of the individuals (see table 2). statistical tests deviations from hardy-weinberg equilibrium (hwe) was tested using the “exact hw test” locus annealing sec. at each cycles pcr machine temp. (z) step (y) (x) cph3 50 °c 15a 37 unitec2042 cph6 49 °c 50a 37 robocycler gradient cph9 55 °c 15 35c unitec2042 cph15 54 °c 15 34 hybaid cph16 54 °c 15a 53 unitec2042 cph18 66 °c 30a,b 31 robocycler gradient a last cycle with extension time: 5 min. b all but last cycle with extension time: 40 sec. c touch down pcr: two cycles with annealing temp. at each table 1. pcr conditions. degree from 45 °c to 54 °c, followed by 25 cycles at annealing temp. 55 °c. locus/ thule scoressøndre julianeallele air base bysund strømfjord håb cph3/151 0.026 153 0.536 0.132 0.316 155 0.107 0.026 0.079 157 0.036 0.184 0.211 0.100 161 0.250 0.474 0.105 0.350 163 0.071 0.053 0.132 0.350 165 0.079 0.026 0.175 167 0.053 169 0.026 0.025 171 0.026 173 0.026 179 0.026 n 28 38 38 40 cph6/109 0.222 0.158 0.400 119 0.667 0.028 121 0.053 0.250 123 0.028 0.105 0.125 125 0.278 0.316 0.075 127 0.222 0.211 0.150 129 0.222 0.158 133 0.333 n 30 36 38 40 cph9/152 0.344 0.028 0.368 0.675 154 0.031 0.250 0.237 0.075 156 0.438 0.639 0.342 0.175 158 0.188 0.053 0.050 162 0.025 164 0.083 n 32 36 38 40 cph15/153 0.167 0.132 0.050 0.050 155 0.033 0.079 0.075 0.200 157 0.667 0.658 0.675 0.550 159 0.053 0.125 0.150 161 0.133 0.026 0.075 0.050 163 0.026 165 0.026 n 30 38 40 40 cph16/155 0.075 159 0.156 0.105 0.175 0.025 161 0.656 0.632 0.250 0.100 163 0.188 0.263 0.525 0.725 165 0.025 0.075 167 0.025 n 32 38 40 40 cph18/253 0.028 0.184 255 0.059 0.053 257 0.125 0.056 0.441 0.289 259 0.167 0.029 0.026 263 0.031 0.028 0.206 0.053 265 0.781 0.083 0.118 0.026 267 0.063 0.056 0.088 0.105 269 0.500 0.158 271 0.083 0.059 0.105 n 32 36 34 38 table 2. observed allele frequency distributions by locus and population. private alleles are shown in italics. boldface indicates the most frequent allele/locus/population. n indicates number of chromosomes. 78 genetic differentiation of populations of greenlandic arctic fox in genepop (raymond & rousset 1995). the sequential bonferroni technique (rice 1989) was applied to test significant deviation from hwe at a “table-wide” α-level of 0.05. test for genotypic disequilibrium was performed in genepop using fisher ś exact test (raymond & rousset 1995). fisher ś exact test was also used to estimate levels of genic differentiation between colour morphs and sampling seasons within locations. the sequential bonferroni technique (rice 1989) was applied to test for significance at the “table-wide” α-level of 0.05. population differentiation was quantified in three different ways both within the total population and between all populations pairwise: 1) by fisher ś exact test in genepop; 2) by estimating rho using goodmaǹ s (1997) analogue to slatkin ś rst (calculated in rst-calc 2.2; rst estimates are based on the smm); and 3) by estimating the weir & cockerham (1984) analogues to wright ś fst calculated in arlequin. fst estimates are based on the iam. all three methods were applied to the total population and to each pair of populations. genepop and rst-calc 2.2 provided probability values and rho estimates, respectively, for individual loci and overall loci, while arlequin only provided fst estimates of overall loci. furthermore, rst-calc 2.2 provided bootstrap values as well as significance values for all estimates, making it possible to see if two rho values differ significantly from each other. estimates of the number of migrants per generation (nm) between all pairwise populations was computed from the approximations: nm= 1/4 (1/fst -1) (slatkin 1995b) and nm=1/4 (1/rho -1) (pers. comm., bo simonsen). nm was also estimated using slatkin ś rare alleles method which makes use of the fact that the logarithm of nm is approximately linearly related to the logarithm of the average frequency of private alleles in a sample of alleles from the population (slatkin 1985). this method has shown to be relatively insensitive to changes in other parameters than nm and the number of individuals sampled per population (slatkin 1985). results genetic variation and deviation from hardyweinberg equilibrium the six loci—cph3, cph6, cph9, cph15, cph16 and cph18—were polymorphic with 12, 8, 6, 7, 6 and 9 alleles, respectively (table 2). the average number of alleles per locality ranged from 4 in cph16 to 7 in cph3 and cph18, and average expected heterozygosity values for all loci ranged from 0.54 in thule air base to 0.73 in søndre strømfjord (see table 3). there was highly significant deviation from hwe in the total population (p ≤ 0.002). all loci showed deficiency of heterozygotes (table 3). no significant deviation from the hwe at the “tablewide” 0.05 level was found in any of the four separate populations (table 3). looking at each locus across localities, two loci , one in each locality, showed significant deviation from hwe due to ho he p(hwe) thule air base cph3 0.57 0.66 0.077 ns cph6 0.27 0.46 0.232 ns cph9 0.69 0.68 0.394 ns cph15 0.33 0.53 0.012 ns cph16 0.50 0.53 0.827 ns cph18 0.44 0.38 1.000 ns scoresbysund cph3 0.68 0.73 0.169 ns cph6 0.72 0.80 0.927 ns cph9 0.61 0.54 0.863 ns cph15 0.47 0.55 0.308 ns cph16 0.53 0.53 0.831 ns cph18 0.61 0.72 0.108 ns søndre strømfjord cph3 1.00 0.84 0.035 ns cph6 0.89 0.86 0.251 ns cph9 0.68 0.71 0.229 ns cph15 0.50 0.53 0.377 ns cph16 0.60 0.65 0.184 ns cph18 0.59 0.76 0.011 ns julianehåb cph3 0.65 0.73 0.196 ns cph6 0.65 0.75 0.899 ns cph9 0.35 0.52 0.079 ns cph15 0.50 0.65 0.041 ns cph16 0.35 0.46 0.070 ns cph18 0.79 0.85 0.395 ns total pop. cph3 0.74 0.81 0.001 s cph6 0.64 0.86 0.000 s cph9 0.58 0.69 0.001 s cph15 0.46 0.57 0.002 s cph16 0.49 0.64 0.001 s cph18 0.61 0.85 0.000 s table 3. expected (he) and observed (ho) heterozygocity and probability values for “the exact hw test” calculated for each locus in every population. s and ns indicate significance and nonsignificance, respectively, at the “table-wide” 0.05 level. nonsignificant p-values across populations are shown in italics. 79meinke et al.: polar research 20(1), 75–83 foxes, while the other five loci showed nonsignificant results (table 4). to compare population differentiation of the white foxes with the blue foxes, rho estimates were calculated for each colour. these rho estimates were calculated for all pairwise localities in which the colours were sampled, and for the total population (table 5). the results for the blue foxes showed highly significant (p < 0.001) subdivision of the total sample; there was significant population differentiation (p < 0.05) in all pairwise comparisons except between thule air base and scoresbysund and between søndre strømfjord and julianehåb. white foxes also showed significant subdivision of the total sample (p < 0.01) and in all pairwise population comparisons (p < 0.05). none of the rho estimates calculated for blue and white foxes were significantly different from each other or from the rho estimates of the populations of both colours (overlap in 95 % confidence intervals, see table 5). in the test for difference in allele frequencies between the seasons, foxes at thule air base showed a significant difference in allele frequency between two sampling occasions (winter and summer) in two out of six loci (table 6). no significant difference was found between the allele frequencies of two sub-samples from scoresbysund (winter and spring), nor beween two subsamples from julianehåb (two consecutive spring seasons) (table 6). population structure the results for all loci from the three different tests for population subdivision are presented in table 7. the first of the results to be noted is that fisher ś exact test showed highly significant subdivision (p < 0.00001) of the total population in all but one locus (cph15). in five of the six pairs of localities, significant differentiation in allele frequencies was supported locus scoresbysøndre julianehåb scoresbysund sund strømfjord + s. strømfjord + julianehåb cph3 0.5390 ns 0.5928 ns 1.0000 ns 0.502 ns cph6 0.7613 ns 0.1179 ns 0.1356 ns 0.082 ns cph9 0.2312 ns 0.1627 ns 0.0240 ns 0.160 ns cph15 0.2731 ns 0.4658 ns 0.0641 ns 0.307 ns cph16 1.0000 ns 0.0103 ns 0.4752 ns 0.294 ns cph18 0.7009 ns 0.0195 ns 0.0092 ns 0.007 s table 4. results (p-values) from fisher ś exact test for differentiation between blue and white foxes. s and ns indicate significance and nonsignificance, respectively, at the “tablewide” 0.05 level. rho est., thule air base thule air base thule air base scoresbysund scoresbyund s. strømfjord total pop. all loci −scoresbysund −s. strømfjord −julianehåb −s. strømfjord −julianehåb −julianehåb blue 0.065 ns 0.152* 0.222*** 0.224** 0.191** 0.050 n 0.159*** foxes (0.020; 0.222) (0.152; 0.374) (0.174; 0.364) (0.152; 0.430) (0.121; 0.352) (0.007; 0.303) (0.141; 0.278) white 0.080* 0.180** 0.144** 0.128** foxes (0.022; 0.246) (0.101; 0.390) (0.080; 0.367) (0.086; 0.290) table 5. population differentiation with populations separated according to fur colour. significance levels: ∗ = p < 0.05; ∗∗ = p < 0.01; ∗∗∗ = p < 0.001. ns indicates a nonsignificant result. 95 % confidence interval is provided in parentheses. heterozygote deficiency: cph15 in thule air base and cph18 in søndre strømfjord (shown in italics in table 3). all other loci across localities showed no deviation from hwe. linkage disequilibrium was found in no pair of loci in the global test across all localities (probability values ranging from 0.07 to 0.96; data not shown). within the populations, the same test demonstrated two cases of linkage disequilibrium (data not shown): the locus pair cph9−cph18 showed significant linkage in thule air base (p = 0.007) and the pair cph9−cph16 showed linkage in scoresbysund (p = 0.03). dividing populations according to colour and time of sampling to test for differentiation in allele frequencies between the two colour morphs we divided each sample according to fur colour. thule air base was omitted from this test as white foxes there were represented by only one animal. the remaining three localities contained sub-samples of at least six individuals each (fig. 1). no significant differentiation was found between allele frequencies of the two colour morphs in any of the localities (table 4). by using the same test on the three localities pooled, cph18 showed a significant difference in allele frequencies of blue and white 80 genetic differentiation of populations of greenlandic arctic fox by from four to all of six loci. it was only between thule air base and søndre strømfjord that half of the loci showed no significant differentiation in allele frequencies. the second of the results to be noted is that rho estimates showed a highly significant population subdivision within the total population (p < 0.001) and a significant population differentiation between all pairwise combinations of populations (p < 0.05). furthermore, bootstrap results showed that none of the rho results from the pairwise locality studies were significantly different from another (overlap between all the 95 % confidence intervals), although they ranged from 0.065 (thule air base−søndre strømfjord) to 0.226 (thule air base−julianehåb). third, fst estimates also showed a highly significant population subdivision (p < 0.001) within the total population. furthermore, this estimate showed highly significant population differentiation (p < 0.001) between all combinations of populations. to find possibly deviant loci we looked at the population differentiation results locus-wise and found the following facts notable: 1) when correcting the significance values locus-wise (horizontally in table 7) according to the sequential bonferroni technique (results not shown), cph15 showed nonsignificant population differentiation in all pairwise population comparisons and nonsignificant subdivision of the total population. cph9 showed nonsignificant result in two of the six pairwise population comparisons, cph3,6 and 16 in only one, and cph18 showed no nonsignificant probability values. 2) there was a large span in the rho estimates of individual loci within all pairwise population comparisons, ranging from a negative value (around -0.03) to 0.246 (table 7). migration the estimated number across the total population of migrating individuals calculated from the rho and the fst estimates was 1.71 and 1.32 individuals/generation respectively (table 8) and 2.05 individuals/generation when estimated by using private alleles according to slatkin (1985) (data not shown). in the pairwise population comlocus thule air base scoresbysund julianehåb (winter 1992 (winter 1993 (spring 1992 −summer 1992) −spring 1994) −spring 1993) cph3 0.0015 s 0.8920 ns 0.0828 ns cph6 0.7060 ns 0.4773 ns 0.4178 ns cph9 0.0746 ns 0.4729 ns 0.0563 ns cph15 0.4734 ns 0.3427 ns 0.3745 ns cph16 0.1435 ns 0.8863 ns 0.8987 ns cph18 0.0060 s 0.6906 ns 0.5028 ns table 6. results (probability values) from fisher ś exact test for difference in allele frequency between foxes sampled indifferent seasons. s and ns indicate significance and nonsignificance, respectively, at the “table-wide” 0.05 level. table 7. population differentiation. probability values from fisher’s exact test. s and ns refer to significance and nonsignificance, respectively, at the “table-wide” 0.05 level. rho estimates and fst estimates are shown. significance levels: *= p < 0.05; ** = p < 0.01; *** = p < 0.001. 95% confidence interval is provided in parentheses for rho estimates over all loci. estimate/ thule air base thule air base. thule air base scoresbysund scoresbysund s. strømfjord total pop. loci −scoresbysund −s. strømfjord −julianehåb −s. strømfjord −julianehåb −julianehåb g. diff. cph3 0.0013 s 0.1314 ns 0.0000 s 0.0020 s 0.0019 s 0.0000 s 0.0000 s cph6 0.0000 s 0.0000 s 0.0000 s 0.5661 ns 0.0000 s 0.0002 s 0.0000 s cph9 0.0000 s 0.0421 ns 0.0082 s 0.0001 s 0.0000 s 0.0256 ns 0.0000 s cph15 0.4252 ns 0.1323 ns 0.0095 s 0.4848 ns 0.2088 ns 0.5428 ns 0.1108 ns cph16 0.6412 ns 0.0040 s 0.0000 s 0.0058 s 0.0000 s 0.0099 s 0.0000 s cph18 0.0000 s 0.0000 s 0.0000 s 0.0000 s 0.0003 s 0.0054 s 0.0000 s rho cph3 0.283 0.059 0.633 0.052 0.092 0.306 cph6 -0.019 -0.027 0.250 -0.025 0.157 0.219 cph9 0.067 0.036 0.157 0.236 0.349 0.035 cph15 -0.030 -0.010 -0.030 -0.015 -0.027 -0.010 cph16 -0.006 0.123 0.151 0.057 0.092 -0.015 cph18 0.058 0.246 0.115 0.332 0.215 -0.026 all loci 0.070** 0.065* 0.226*** 0.117*** 0.165*** 0.089** 0.128*** (0.018; 0.180) (0.028; 0.182) (0.178; 0.336) (0.057; 0.232) (0.093; 0.285) (0.053; 0.191) (0.107; 0.206) fst 0.198*** 0.175*** 0.262*** 0.096*** 0.169*** 0.070*** 0.159*** 81meinke et al.: polar research 20(1), 75–83 parison the nm values calculated from the rho estimates ranged from 0.86 between thule air base and julianehåb to 3.61 between thule air base and søndre strømfjord, but, as with the rho estimates, not one of the values was significantly different from another according to the bootstrap results. the nm values calculated from the fst estimates in the pairwise population comparisons showed about the same range: from 0.70 (thule air base−julianehåb) to 3.34 (søndre strømfjord−julianehåb). discussion four randomly mating populations the heterozygote deficiency found in the total greenlandic sample can probably be ascribed to a wahlund effect created when pooling the four populations. these hwe results give a preliminary indication that the population is subdivided in spite of the arctic fox’s capacity for long-distance movements. furthermore, the hwe results showed that each of the four localities can be seen as a randomly mating population (no deviation from hwe). the fact that two loci (cph15 and cph18), one each in two different populations, showed a significant deviation from hwe, looking across all populations, cannot be explained by null alleles: if the two loci had null alleles we would expect it to affect the other populations as well, which was not the case. it is, of course, possible that non-detectable alleles causing heterozygote deficiency of cph15 and cph18 only were present in thule air base and in søndre strømfjord, respectively, but since all but one private allele in the total data set had very small allele frequencies (p ≤ 0.05; table 2), this appears unlikely. we cannot explain these significant results since explanations such as assortative mating or pooling of samples (resulting in the wahlund effect) would be expected to affect the other loci of the populations as well and that is not the case. the two colour morphs there seems to be a positive correlation between the period of time an area is snow-covered and the proportion of white foxes in this area (braestrup 1941; vibe 1967; hersteinsson 1989). if this is due to a sharply defined difference in habitat, interbreeding between the morphs would only exist in a small hybrid zone, and we would expect to find a difference in allele frequencies between the morphs and certainly not random mating between them. kapel et al. (1996) found no significant difference between the prevalence of trichinella nativa infections in the blue and the white foxes, respectively, which were also used for the study reported here. t. nativa is an extraintestinal nematode which is most prevalent in foxes in areas where polar bears are hunted and sledge dogs are common (kapel 1995). the nematode is thought to be transmitted to the arctic fox through scavenging on carcasses of these animals or through cannibalism. the fact that kapel found no difference in the prevalence of this parasite according to colour of the foxes could indicate that the two morphs share the same habitat and diet. the results of this study indicate random mating within the three populations of mixed colours and no allele frequency difference between the two colour morphs. it is important to note that the statistical power may have been small due to small sample sizes. however, our data suggest that the two colour morphs of the greenlandic arctic fox share the same habitat, at least during the mating season. the investigation of differentiation within the blue and the white fox groups (table 5) yields no indication that the blue fox is more stationary than the white one. on the contrary, rho estimates failed to show significant difference between the estimate/ thule air base thule air base thule air base scoresbysund scoresbysund s. strømfjord total pop. loci −scoresbysund −s. strømfjord −julianehåb −s. strømfjord −julianehåb −julianehåb nm (rho) 3.34 3.61 0.86 1.89 1.26 2.54 1.71 (1.07; 12.0) (1.11; 8.58) (0.49; 1.15) (0.82; 3.91) (0.61; 2.42) (1.05; 4.41) (0.96; 2.07) nm (fst) 1.01 1.18 0.70 2.35 1.23 3.34 1.32 table 8. migration rate. nm values correspond to the rho and fst estimates shown in table 6. 95 % confidence interval is provided in parentheses for the nm corresponding to rho estimates. 82 genetic differentiation of populations of greenlandic arctic fox blue foxes of søndre strømfjord and julianehåb while significant differentiation (p < 0.01) was found between the white foxes from the same localities. these results indicate that the difference berg (1993) found with respect to morphological differentiation of greenlandic blue and white foxes was a result of ecological rather than genetic differences, as berg also discusses. the different sampling seasons two of the four populations (thule air base and scoresbysund) in this study were sampled in both winter and spring/summer seasons (fig. 1). theories have been proposed that the foxes migrate in november-january and return to their “home” in february−march to breed—the “homing theory” (russian studies reviewed by wrigley & hatch 1976). if this is the case, sampling in winter will lead to sampling of migrants that will eventually return to their own locality and therefore have no genetic impact on the locality in which they were found. winter populations will be a mixture of mating populations and we would expect to find a difference in allele frequencies between a winter and a summer sample from the same locality. we tried to test this theory by testing for genic differentiation between the sub-samples of thule air base and scoresbysund. however, in testing the homing theory this way, we have a problem in the transition between winter and mating populations. scoresbysund was artificially divided into two sub-samples: one on each side of 1 march 1994. the results of thule air base neither clearly supported nor disproved the theory and we have to conclude that our data set cannot be used to test the homing theory. samples from more populations, collected in both winter and summer, are needed. population structure distinct geographically differences in the composition of the parasitic helminth fauna of arctic fox in greenland have been found (kapel et al. 1996; kapel & nansen 1996). the diversity of the surrounding fauna and thereby the food items available for the foxes seemed important influences on the diversity of the helminth species (kapel & nansen 1996). these results indicate limited mixing of the studied populations. the present study supports this indication. all three approaches to analysing population differentiation (fisher ś exact test, fst estimates and rho estimates) showed that the total sample of greenlandic arctic fox was significantly differentiated into subpopulations. the rho and the fst estimates across all loci also showed significant population differentiation between all pairwise populations included in the study. population differentiation results for individual loci are provided by fisher ś exact test and as rho estimates. in both tests cph15 was the only locus consistently showing no difference between any two populations, and it even showed no significant subdivision of the total population in fisher ś exact test (table 7). on this basis we suggest that cph15 is not a neutral locus. slatkin (1995a) showed that the variance of microsatellite allele size can be strongly influenced by selection at closely linked loci. cph15 could be linked to a locus under selection or it could be involved in gene expression, resulting in a reduction in the variance of allele size of this microsatellite in a way that makes population subdivision less detectable with this locus. migration the three different methods we have used to estimate average nm between the populations of this study gave very consistent results around one to two migrating foxes between each locality every generation. the distances between the localities of this study range from 825 km between søndre strømfjord and julianehåb to 1950 km between thule air base and julianehåb. from our data we cannot discern if, for instance, one fox per generation travels the distance between thule air base and julianehåb or if the estimate is a result of a larger gene flow between all adjacent populations along the distance between thule air base and julianehåb. in this regard it would be interesting to get estimates of differentiation and migration between populations separated by shorter distances (including adjacent populations) and to extend the study to involve more loci and/or individuals to increase statistical power. conclusion we have found evidence of extensive genetic differentiation between four arctic fox localities, 83meinke et al.: polar research 20(1), 75–83 demonstrating that the ability of arctic foxes to undertake long-distance movements has not resulted in a panmictic greenlandic population. the foxes examined in this study do not show genetic differentiation between the two colour morphs within each locality. this suggests that the two colour morphs of the greenlandic arctic fox can be considered as members of the same populations. a test for population differentiation within each of the two colour morphs indicated that they are equally stationary. acknowledgements.—we thank thomas berg for assistance during the fieldwork; marie-agnés coutellec-vreto and silvester nyakaana for statistical assistance; michael roy for technical advice and support; jacob damgaard for comments on an earlier version of the manuscript; and lisette rasmussen for linguistic assistance. we also thank merete fredholm and anne katrine winterø for technical assistance optimizing the pcr reactions. the commission for scientific research in greenland partly supported this work. references adalsteinsson, s., hersteinsson, p. & gunnarsson, e. 1987: fox colours in relation to colours in mice and sheep. j. hered. 78, 235–237. anthony, r. m. 1997: home ranges and movements of arctic fox (alopex lagopus) in western alaska. arctic 50, 147–157. berg, t. b. 1993: polarræven i grønland. (the arctic fox in greenland.) m.sc. thesis, copenhagen university, denmark. braestrup, f. w. 1941: a study on the arctic fox in greenland. medd. grønl. 131, 1-101. callen, d. f., thompson, a. d., shen, y., phillips, h. a., richards, r. i., mulley, j. c. & sutherland, g. r. 1993: incidence and origin of “null” alleles in the (ac)n microsatellite markers. am. j. hum. genet. 52, 922–927. eberhardt, l. e. & hanson, w. c. 1978: long-distance movements of arctic foxes tagged in northern alaska. can. field-nat. 92, 386–389. eberhardt, l. e., garrott, r. a. & hanson, w. c. 1983: winter movements of arctic foxes, alopex lagopus, in a petroleum development area. can. field-nat. 97, 66–70. estoup, a., garnery, l., solignac, m. & cornuet, j.-m. 1995: microsatellite variation in honey bee (apis mellifera l.) populations: hierarchical genetic structure and test of the infinite allele and stepwise mutation models. genetics 140, 679–695. fay, f. h. & rausch, r. l. 1992: dynamics of the arctic fox population on st. lawrence island, bering sea. arctic 45, 393–397. frafjord, k. & prestrud, p. 1992: home range and movements of arctic foxes alopex lagopus in svalbard. polar biol. 12, 519–526. fredholm, m. & winterø, a. k. 1995: variation of short tandem repeats within and between species belonging to the canidae family. mamm. genome 6, 11–18. garrott, r. a. & eberhardt, l. e. 1987: arctic fox. in m. novak et al. (eds.): wild furbearer management and conservation in north america. pp. 395–406. toronto: ministry of natural resources. garza, j. c., slatkin, m. & freimer, n. b. 1995: microsatellite allele frequencies in humans and chimpanzees, with implications for constraints on allele size. mol. biol. evol. 12, 594–603. goodman, s. j. 1997: r st calc: a collection of computer programs for calculating estimates of genetic differentiation from microsatellite data and determining their significance. mol. ecol. 6, 881–885. hersteinsson, p. 1989: population genetics and ecology of different colour morphs of arctic foxes alopex lagopus in iceland. finn. game res. 46, 64–78. kapel, c. m. o. 1995: helminths of the arctic fox (alopex lagopus (l.)) in greenland. ph.d. thesis, the royal veterinary and agricultural university, copenhagen. kapel, c. m. o. 1999: diet of arctic foxes (alopex lagopus) in greenland. arctic 52, 289–293. kapel, c. m. o., henriksen, s. a., berg, t. b. & nansen, p. 1996: epidemiologic and zoogeographic studies on trichinella nativa in arctic foxes, alopex lagopus, in greenland. j. helminthol. soc. wash. 63, 226–232. kapel, c. m. o. & nansen, p. 1996: gastrointestinal helminths in arctic foxes (alopex lagopus) from different bioclimatological regions in greenland. j. parasitol. 82, 17–24. kashi, y., king, d. & soller, m. 1997: simple sequence repeats as a source of quantitative genetic variation. trends genet. 13, 74–78. raymond, m. & rousset, f. 1995: an exact test for population differentiation. evolution 49, 1280–1283. rice, w. r. 1989: analysing tables of statistical tests. evolution 43, 223–225. sambrook, j., fritsch, e. f. & maniatis, t. 1989: molecular cloning: a laboratory manual. second edition. new york: cold spring harbor laboratory press. shriver, m. d., jin, l., chakraborty, r. & boerwinkle, e. 1993: vntr allele frequency distributions under the stepwise mutation model: a computer simulation approach. genetics 134, 983–993. slatkin, m. 1985: rare alleles as indicators of gene flow. evolution 39, 53–65. slatkin, m. 1995a: hitchhiking and associative overdominance at a microsatellite locus. mol. biol. evol. 12, 473–480. slatkin, m. 1995b: a measure of population subdivision based on microsatellite allele freqencies. genetics 139, 457–462. valdes, a. m., slatkin, m. & freimer, n. b. 1993: allele frequencies at microsatellite loci: the stepwise mutation model revisited. genetics 133, 737–749. vibe, c. 1967: arctic animals in relation to climatic fluctuations. medd. grønl., biosci., 170, 7–227. weber, j. l. & wong, c. 1993: mutation of human short tandem repeats. hum. mol. genet. 2, 1123–1128. weir, b. s. & cockerham, c. c. 1984: estimating f-statistics for the analysis of population structure. evolution 38, 1358–1370. wrigley, r. e. & hatch, d. r. m. 1976: arctic fox migrations in manitoba. arctic 29, 147–158. historic temperature observations on nordaustlandet, north-east svalbard research article historic temperature observations on nordaustlandet, north-east svalbard björn-martin sinnhuber karlsruhe institute of technology, institute of meteorology and climate research, eggenstein-leopoldshafen, germany abstract long-term meteorological data for the arctic are sparse. one of the longest quasi-continuous temperature time series in the high arctic is the extended svalbard airport series, providing daily temperature data from 1898 until the present. here, i derive an adjustment to historic temperature observations on the island of nordaustlandet, north-east svalbard, in order to link these to the extended svalbard airport series. this includes the haudegen observations at rijpfjorden during 1944/45 and a previously unrecognized data set obtained by the norwegian hunters and trappers gunnar knoph and henry rudi during their wintering at rijpfjorden in 1934/35. the adjustment is based on data from an automatic weather station at rijpfjorden during 2014–16 and verified with other independent historic temperature observations on nordaustlandet. an analysis of the haudegen radiosonde data indicates that the surface temperature observations at rijpfjorden are generally well correlated with the free tropospheric temperatures at 850 hpa, but occasionally show the occurrence of boundary-layer inversions during winter, where local temperatures fall substantially below what is expected from the regression. the adjusted historic observations from nordaustlandet can, therefore, be used to fill remaining gaps in the extended svalbard airport series. keywords climate change; arctic amplification; early 20th century warming; hunters’ diaries; henry rudi; oxford university arctic expedition 1935/36 abbreviations aws: automatic weather station rmse: root mean square error unis: university centre in svalbard   citation: polar research 2021, 40, 7564, http://dx.doi.org/10.33265/polar.v40.7564 copyright: polar research 2021. © 2021 b.-m. sinnhuber. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 20 july 2021 competing interests and funding: the author reports no conflict of interest. bms was funded by the german helmholtz society through the atmo programme. the author acknowledges support by the kit-publication fund of the karlsruhe institute of technology. correspondence to: björn-martin sinnhuber, karlsruhe institute of technology, institute of meteorology and climate research, hermann-von-helmholtz-platz 1, de-76344 eggenstein-leopoldshafen, germany. e-mail: bjoern-martin.sinnhuber@kit.edu introduction the arctic climate is changing rapidly, with the arctic rate of warming much larger than the global average warming, the so-called arctic amplification (stocker et al. 2013; przybylak & wyszynski 2020). although it is well established that anthropogenic emissions of greenhouse gases are the dominant drivers of the ongoing arctic climate change, the relative contribution of different natural and anthropogenic forcings, together with internal variability of the climate system, to the observed changes over the past 100 years is still not fully understood. in particular, the observed arctic warming during the early 20th century (grant et al. 2009; wood et al. 2010; yamanouchi 2011; xiao et al. 2020) is still not well reproduced in most climate models (fyfe et al. 2013). it remains uncertain (e.g., przybylak 2000, 2007) whether the early 20th century warming primarily reflects internal variability of the coupled climate system (bengtsson et al. 2004) or if anthropogenic and natural aerosol forcings play a dominant role (fyfe et al. 2013). long-term meteorological reference data for the arctic are sparse, in particular for the early 20th century. one of the longest quasi-continuous temperature time series in the high arctic is the homogenized extended svalbard airport series (nordli et al. 2014; nordli et al. 2020). observations have been taken at svalbard airport only since 1975, so they have been merged with earlier observations at other places in spitsbergen. this approach has resulted in a time-series of daily mean temperatures from 1898 to the present (nordli et al. 2020). to connect observations at other places with the svalbard airport time series, adjustments based on a linear regression have been applied. this approach has benefitted from the recent installation of awss at or close to the sites of historic temperature observations (e.g., przybylak et al. 2014), so that regressions between the local and primary time series could be established. interruption of routine meteorological observations during world war ii resulted in a gap in the extended svalbard airport series between august 1941 and september 1945. this is particularly unfortunate, as this gap occurred around the maximum of the early 20th century warming. there have been various military meteorological observations in svalbard during world war ii, from german as well as allied and norwegian operations (blyth 1951; elbo 1952; selinger & glen 1983) that could potentially fill this gap if the original data could be retrieved. here, i present an adjustment of the well-known temperature observations from the german military weather station haudegen from august 1944 to september 1945 (dege 1960, 2004, 2006) to link it to the extended svalbard airport series. haudegen was in rijpfjorden, at the northern coast of nordaustlandet, in north-east svalbard. nordaustlandet is the second-largest island of the svalbard archipelago (and, in fact, the 55th largest island of the world) and largely covered by two ice caps: vestfonna and austfonna. the climate of nordaustlandet is much colder than that of western spitsbergen, which is under the influence of the relatively warm waters of the west spitsbergen current. nordaustlandet, in contrast, experiences a more severe high arctic climate. this warrants extra efforts to establish the adjustment of the haudegen observations with the svalbard airport series. unfortunately, there are only five days of overlap between the haudegen observations and the extended svalbard airport series, much too short to establish an adjustment. instead, observations taken by an aws at rijpfjorden 19 km north of the haudegen site, operated by unis between 2007 and 2016, are used here to derive the adjustment between the rijpfjorden and svalbard airport temperature series. year-round temperature observations at nordaustlandet are very sparse. dege (1960) refers to the oxford university arctic expedition during 1935/36 (glen 1937, 1939; glen & croft 1937; hamilton 1938, 2012) as the first year-round meteorological record at nordaustlandet. during the international geophysical year, a swedish–finnish–swiss expedition took detailed meteorological observations at kinnvika, murchison bay, nordaustlandet, from july 1957 to august 1958 (liljequist 1959, 1960). just by chance, i recently discovered a year-round data set of temperature observations at rijpfjorden for august 1934 to august 1935, recorded by the hunters and trappers gunnar knoph and henry rudi, who overwintered close to the later haudegen site. their diary, which includes their meteorological observations, is publicly available through the archive of the norwegian polar institute (knoph 1945), but this data set has apparently gone unnoticed by the meteorological or climate literature. the objective of this work is to present the available year-round temperature observations at nordaustlandet, to establish an adjustment of the haudegen measurements to the extended svalbard airport series and to validate this adjustment with the other historic observations at nordaustlandet. as the 1934/35 temperature observations are available only at 22:00 hours, the hourly rijpfjorden aws observations during 2014–16 are analysed to derive the diurnal temperature variation at rijpfjorden during the individual months of the year. the haudegen radiosonde observations during 1944/45 are analysed, with a focus on determining the extent to which low temperatures during winter are connected with boundary-layer inversions, which would decouple the surface temperatures from the free tropospheric temperatures and make these observations less representative of a larger area. data and methods an overview of the temperature data sets used in this study is provided in fig. 1 and table 1. these are essentially all available longer-term (a year or longer) temperature time series in nordaustlandet before the late 20th century. in recent years, a number of awss have been installed (at least temporarily) at various places in nordaustlandet and on nearby islands (e.g., pohjola et al. 2011; przybylak et al. 2014). early temperature observations from svalbard, including from ships that travelled around nordaustlandet in the period from 1865 to 1920, were presented by przybylak et al. (2016) but were limited to summer months with open sea. the first month-long temperature series on nordaustlandet itself was taken by the swedish–norwegian arctic expedition at their sveanor station in murchison bay from 30 june to 10 august 1931 (ahlmann et al. 1933). however, murchison bay is located in the very west of nordaustlandet, at the hinlopen strait and rather close to crozierpynten on the spitsbergen main island, where meteorological measurements had already been taken between august 1899 and august 1900 (przybylak et al. 2016; nordli et al. 2020).   table 1 temperature time series considered in this study. all stations are at sea level. time series location period references rijpfjorden 1934/35 79°59’30’’n, 22°17’20’’e 31 aug 1934–9 aug 1935 knoph (1945) oxford university arctic expedition oxford expedition, murchison bay 80°23’05’’n, 19°29’16’’e 79°58’n, 18°20’e 24 aug 1935–12 aug 1936 8 may 1936–31 jul 1936 glen (1937, 1939); hamilton (1938) glen (1937); hamilton (1938) haudegen 1944/45 80°02’55’’n, 22°31’10’’e 15 sep 1944–5 sep 1945 dege (1960) rijpfjorden aws 80°13’n, 22°29’e 17 may 2014–28 sep 2016a unis (pers. comm.) murchison bay 1957/58 80°03’06’’n, 18°13’14’’e 19 jul 1957–30 aug 1958 liljequist (1959) crozierpynten aws 79°55’07’’n, 16°50’40’’e 11 jul 2010–6 jul 2012b eklima.met.no asome data since 25 january 2007. bsome data from 2014 and later. fig. 1 location of the temperature records considered in this study: rijpfjorden 1934/35 (1), oxford university arctic expedition 1935/36 (2/2a), haudegen 1944/45 (3), murchison bay (murchinsonfjorden) 1957/58 (4), crozierpynten aws 2010–12 (5), rijpfjorden aws 2014–16 (6). longyearbyen/svalbard airport is marked with an asterisk in the inset map. (maps modified from toposvalbard.npolar.no.) knoph and rudi, rijpfjorden 1934/35 the norwegian hunters and trappers gunnar knoph and henry rudi spent 1934/35 at rijpfjorden. their main base was located at the innermost part of the fjord rijpfjorden, about 8 km south of the haudegen site, with subsidiary stations along both sides of rijpfjorden, one of them right next to the later haudegen site. a diary with meteorological observations was compiled by knoph in march 1945 and addressed to adolf hoel, then director of the svalbard and arctic ocean survey, which later became the norwegian polar institute (knoph 1945). knoph’s diary contains daily temperature observations between 31 august 1934 and 9 august 1935, with the temperature readings typically given without decimal places, only occasionally at half a degree resolution. unfortunately, no details on the instrumentation are given by knoph (1945). for most days, observations are reported for 22:00 hours; for a few days, there are additional readings for 08:00 and 12:00. the daily temperature observations at 22:00 have been digitized here. later in this article, i will use the hourly 2014–16 aws data from rijpfjorden to investigate to what extent the observations at 22:00 can be considered representative for the diurnal mean. for determining the absolute minimum and maximum temperatures at rijpfjorden in 1934/35, in addition to the 22:00 observations, the small number of readings at 08:00 and 12:00 is taken into account as well. nordaustlandet was never of great importance for hunting and trapping. there were a few wintering hunters and trappers on the north-west coast of nordaustlandet in the early 20th century, but knoph and rudi were the only party to winter in the rijpfjorden area (rossnes 1993). because of unfavourable hunting conditions on nordaustlandet, knoph and rudi left nordaustlandet in the summer of 1935 and moved to halvmåneøya, off edgeøya, in south-eastern svalbard (knoph 1945). oxford university arctic expedition 1935/36 the oxford university arctic expedition to nordaustlandet, under the leadership of alexander (“sandy”) glen, operated a main base at depot point at brandy bay (now brennevinsfjorden), on the north-west coast of nordaustlandet. initially, it was planned to place the main base at rijpfjorden, but sea-ice conditions in august 1935 prevented this (glen 1937). continuous meteorological observations were performed at depot point from 24 august 1935 to 12 august 1936 (glen 1937; hamilton 1938). additional meteorological time series were taken at two ice cap stations on vestfonna (not considered here) and at söre russøya in murchison bay (now murchisonfjorden) from 8 may 1936 to 31 july 1936 (hamilton 1938). unfortunately, there is no overlap between the rijpfjorden time series and the oxford expedition data at depot point in august 1935. knoph and rudi left rijpfjorden on 11 august 1935 and paid a visit to the oxford expedition the next day (knoph 1945). richard hamilton, the meteorologist of the oxford expedition, noted in his diary: “we had a surprise visit from two other ships, vesteris and isbjorn, last tuesday [13 august; the date conflicts with that given in knoph’s account], with hunters on board who had wintered in rijps bay [rijpfjorden] and told us to expect a very hard and cold winter” (hamilton 2012: 19). in summer 1936, glen and his company visited the place of knoph and rudi’s former station at rijpfjorden: “there we found the side of a hut which had been built two years before by two norwegian hunters, rudi and knoph, the first ever to winter successfully in north east land [nordaustlandet]. weather conditions were so severe, and hunting so poor, that in the following year they moved their huts to edge island [edgeøya], 200 miles further south” (glen & croft 1937: 322). for the present study, the monthly mean temperature data of depot point and murchisonfjorden were taken from hamilton (1938). despite some efforts, it was not possible to retrieve the original daily meteorological observations of the oxford university expedition. haudegen, rijpfjorden 1944/45 the german navy operation known as haudegen established the last in a series of military weather stations in svalbard during world war ii (blyth 1951; dege 2004, 2006). commanded by dr wilhelm dege, the base was established at the wordie bay (now wordiebukta) on the eastern side of the inner rijpfjorden in september 1944. it provided detailed three-hourly surface observations from 15 september 1944 until 5 september 1945. in total, 140 radiosondes were launched between 13 november 1944 and 18 june 1945. the original data are provided by dege (1960). surface temperature observations from haudegen have previously been analysed by przybylak et al. (2018), and upper air temperatures from haudegen radiosonde data were analysed by brönnimann et al. (2012). swedish–finnish–swiss expedition at murchison bay 1957/58 during the international geophysical year, the swedish–finnish–swiss expedition to nordaustlandet established a base at kinnvika, on the northern shore of murchisonfjorden. meteorological observations were performed between 19 july 1957 and 30 august 1958, including regular radiosonde launches (liljequist 1959, 1960). here, i use the monthly mean and extreme temperatures as published by liljequist (1959). unfortunately, i was not able to retrieve the original daily temperature observations, only a subset of the kinnvika radiosonde observations. upper air temperatures from radiosonde launches at kinnvika during 1957/58 have been analysed by brönnimann et al. (2012). aws at rijpfjorden an aws was operated by unis on the eastern shore of rijpfjorden between january 2007 and september 2016. as the early data contain many gaps, i consider only temperature observations between 17 may 2014 and 28 september 2016. the temperature data have hourly resolution; daily mean temperatures are calculated by a simple average of the hourly observations. the site of the aws is about 19 km north of the historic haudegen site. aws at crozierpynten in addition to the rijpfjorden aws, observations from an aws at crozierpynten on the northeast coast of the spitsbergen main island are included in the present analysis. crozierpynten is rather close to murchison bay, essentially separated only by the hinlopen strait. we may, therefore, assume that observations at crozierpynten may be more representative for murchison bay than the rijpfjorden observations on nordaustlandet. the aws at crozierpynten operated continuously from 11 july 2010 to 6 july 2012. here, i use daily mean temperature observations, obtained through eklima.met.no. regression with svalbard airport temperature series the present work follows the methodology of nordli et al. (2020) for the adjustment of local temperature time series by linear regression to the svalbard airport series, that is, it is assumed that the two temperature series can be expressed by the linear relation where ts is the principal svalbard airport temperature series, ta is the local temperature series and ε denotes the residual. the two linear coefficients, here called c1 and c2, are determined for each month separately. regressions are calculated for the rijpfjorden aws and crozierpynten aws with the extended svalbard airport series of nordli et al. (2020). results and discussion temperature observations at rijpfjorden the annual series of (unadjusted) daily temperature observations at rijpfjorden for 1934/35, 1944/45, 2014/15 and 2015/16 are shown in fig. 2, together with the corresponding temperatures from the extended svalbard airport series when available. the high degree of correlation between the temperatures at rijpfjorden and svalbard airport is striking. in particular, the winter months are characterized by a very large temperature variability. temperatures often quickly rise from very low temperature to freezing level or even above, well correlated between rijpfjorden and the svalbard airport series. correlation coefficients for winter (december to march) temperatures are 0.92 for 2014–16 and 0.80 for 1934/35. also striking is the large difference in temperatures between the cold winter of 2014/15 and the much warmer winter of 2015/16. it is evident that temperatures at rijpfjorden are typically much lower than at svalbard airport, in particular for the lowest temperatures in winter. notable is the large difference between rijpfjorden and svalbard airport for the coldest temperatures in winter 1934/35, which calls for a more detailed analysis. note also the large difference in summer temperatures between rijpfjorden and svalbard airport for 2014–16, and the much smaller temperature differences in summer 1935. fig. 2 temperature observations at rijpfjorden (blue) in comparison to the svalbard airport time series (red) for 1934/35, 1944/45, 2014/15 and 2015/16. tick marks indicate the beginning of the month. a histogram of the knoph (1945) temperature data shows suspicious peaks at −10°, −20° and −30° (these values about two to three times more frequent than statistically expected), raising some doubts about the accuracy of the temperature measurements. however, in general, the correlation with the svalbard airport series is surprisingly high (monthly correlation coefficients between 0.73 and 0.88, except for the summer months, when also for present-day observations the correlation is weak). table 2 presents monthly means and maximum and minimum readings for the different data sets. the range of observed temperatures in the individual months is comparable between 1934/35 and the other data sets at nordaustlandet, but monthly means for winter 1934/35 are much colder than in any other winter. an analysis of data from the oxford university expedition 1935/36, haudegen 1944/45 and the present-day rijpfjorden aws was presented by przybylak et al. (2018) with respect to long-term temperature trends.   table 2 monthly mean and extreme temperatures (°c) from the historic data sets at nordaustlandet. italics indicate monthly means derived from observations that did not span a full month. jan feb mar apr may jun jul aug sep oct nov dec monthly mean at rijpfjorden 31 aug 1934–9 aug 1935 −24.7 −23.5 −21.0 −17.7 −9.6 +1.7 +5.6 +7.1 +0.3 −5.8 −10.6 −13.8 absolute minimum −37.5 −37 −36.5 −36 −15 −8 −0.5 +1 −4 −11.5 −19 −30 absolute maximum −3 +1 −3 0 0 +8 +12 +12 +5 +4 0 0 monthly mean at depot point 24 aug 1935–12 aug 1936 −12.1 −17.1 −24.1 −15.8 −2.3 +0.7 +2.5 +3.8 −2.6 −1.8 −5.1 −8.8 absolute minimum −29.4 −28.9 −32.2 −28.9 −10.6 −6.7 −2.2 −0.8 −12.2 −15.0 −17.8 −19.4 absolute maximum −1.1 0.0 −5.6 +1.7 +8.3 +11.1 +9.4 +9.4 +5.6 +6.7 +3.3 0.0 monthly mean at murchison bay 8 may–31 july 1936 −2.2 +1.1 +4.2 absolute minimum −7.2 −3.9 −0.8 absolute maximum +6.9 +6.7 +9.4 monthly mean at rijpfjorden 15 sep 1944–5 sep 1945 −16.1 −11.6 −12.5 −13.6 −8.2 +0.2 +4.8 +2.8 +2.1 −3.9 −7.7 −5.3 absolute minimum −35.5 −34.8 −28.9 −32.0 −19.6 −8.6 −1.0 −5.0 −1.5 −13.8 −18.5 −25.5 absolute maximum +0.8 +3.5 +0.3 +1.0 +3.8 +9.0 +13.7 +11.0 +7.2 +5.3 +2.2 +3.2 monthly mean at murchison bay 1 aug 1957–30 jul 1958 −11.2 −15.8 −18.2 −13.6 −4.3 −0.3 +2.3 +3.7 −0.1 −0.9 −8.0 −14.4 absolute minimum −25.6 −27.8 −31.6 −27.7 −16.4 −6.2 −1.2 −1.0 −6.5 −11.4 −18.0 −23.3 absolute maximum 0.0 −3.8 −1.4 +3.4 +1.0 +6.2 +6.4 +9.1 +4.9 +3.0 +1.1 −1.4 monthly mean at rijpfjorden 2014–16 −8.2 −11.6 −9.3 −10.2 −5.2 +0.2 +3.2 +2.3 +0.1 −3.9 −8.0 −10.1 absolute minimum −28.4 −28.5 −30.3 −27.2 −22.0 −7.5 −1.9 −5.0 −7.8 −18.9 −23.4 −32.2 absolute maximum +5.1 +4.6 +4.2 +3.9 +5.2 +8.7 +14.4 +12.5 +9.4 +7.3 +5.3 +5.8 diurnal temperature variations at rijpfjorden as noted earlier, observations for 1934/35 are available only at 22:00 hours. to test the extent to which this introduces a bias compared to the daily mean, i have analysed the diurnal cycle of temperatures at rijpfjorden from the hourly aws measurements in 2014–16. diurnal cycles of the temperature for individual months are shown in fig. 3, expressed as deviations from the mean. a diurnal cycle with a peak-to-peak amplitude of up to about 2 °c becomes evident between april and november. the monthly mean diurnal cycle is, as one would expect, essentially absent during the dark winter months. the rijpfjorden temperature measurements at 21utc (corresponding to 22:00 hours) are biased low with respect to the daily mean at rijpfjorden by −0.25 °c on average during april to september, with no significant bias during the rest of the year. in other words, the use of the 22:00 hours temperature observations instead of daily mean values introduces a negligible error compared to other sources of uncertainties. the variance increases only slightly when using the 21utc temperature measurements instead of the diurnal averages (monthly standard deviation increases by less than 10%), and consequently, the correlation with the svalbard airport time series decreases only slightly. fig. 3 diurnal temperature variation (deviation from daily means) at rijpfjorden for 2014–16. error bars denote one standard error. adjustment to the svalbard airport series regressions between the rijpfjorden aws for 2014–16 with the svalbard airport series are given in table 3. correlations and rmses for the svalbard airport–rijpfjorden relation are comparable or even slightly better than the svalbard airport–crozierpynten relation (nordli et al. 2020). in particular, during the summer months june, july, august, the correlation is very poor for crozierpynten, so that nordli et al. (2020) based the relation on the three summer months together. this was not necessary for rijpfjorden, although also here the correlation during july and august is rather weak.   table 3 regression of temperature time series between svalbard airport (homogenized extended time series) and rijpfjorden (2014–16). jan feb mar apr may jun jul aug sep oct nov dec svalbard airport–rijpfjorden (2014–16) c1 0.802 0.900 0.736 0.584 0.633 0.626 0.352 0.416 0.652 0.712 0.723 0.751 c2 1.02 0.77 −0.01 0.21 2.75 4.37 6.97 5.55 2.76 0.94 0.90 −0.22 r2 (%) 86 88 79 62 78 60 31 37 64 67 74 81 rmse 2.1 2.4 2.6 2.3 1.7 1.2 1.5 1.8 1.3 2.2 2.5 2.4 as there is essentially no overlap between the recent aws time series at rijpfjorden and at crozierpynten, we cannot directly compare the two time series, but comparing the differences with the svalbard airport series allows for an indirect comparison. in the annual average, the temperatures at rijpfjorden are 1.7 °c colder than at crozierpynten. using the adjustment derived from the rijpfjorden aws for 2014–16, we can connect the haudegen temperature series for 1944/45 to the extended svalbard airport series. table 4 presents monthly mean temperatures from october 1944 to august 1945 from the haudegen observations, adjusted to the svalbard airport series. based on the haudegen data, july 1945 would be the warmest in the svalbard airport series before 2015 and august 1945 the warmest before 1998. this is in line with the fact that july and august monthly means at rijpfjorden were much higher in 1945 than during 2015 or 2016 (table 2). however, adjustment of summer temperatures should be treated with great caution on the account of the poor correlation during summer (only 31 and 37% of the variance explained by the regression for july and august, respectively; table 3).   table 4 monthly mean temperatures (°c) from october 1944 to august 1945 based on measurements at rijpfjorden (table 2), adjusted to the svalbard airport series using eqn. (1) with coefficients from table 3. 1944 1945 oct nov dec jan feb mar apr may jun jul aug −1.8 −4.7 −4.2 −11.9 −9.7 −9.2 −7.7 −2.4 +4.5 +8.7 +6.7 validation of adjustments unfortunately, the period of five days of overlap between the haudegen and longyearbyen observations in september 1945 is too short to draw any meaningful conclusion. (note that the 1945 temperature observations made in longyearbyen predated construction of the svalbard airport, about 5 km north-west of the main settlement.) therefore, a validation of the relation between the rijpfjorden and svalbard airport temperature series is performed here by additionally comparing the adjusted monthly mean data for rijpfjorden 1934/35, depot point 1935/36, murchisonfjorden 1935/36 and murchisonfjorden 1957/58 with the svalbard airport series. table 5 presents the monthly biases, as well as the annual average bias, calculated as where δt is the temperature bias and the meaning of the other symbols as in eqn. 1. we see that monthly mean temperatures for the winter months are biased low for 1934/35 when adjusted by the relation based on the rijpfjorden 2014–16 observations, while temperatures are biased high in the late spring and summer. the annual average temperature bias is only −0.2 °c. the december 1934 to march 1935 winter mean temperatures at rijpfjorden were 11 °c colder than 2014–16 (table 2), but the mean bias of the 1934/35 adjusted data for december to march is only −3.5 °c. thus, the remaining bias of the adjustment is small (about one-third) compared to the large temperature differences. for the 1935/36 depot point observations, two adjustments are presented, one based on the rijpfjorden 2014–16 observations and the other based on the crozierpynten 2010–12 observations. in general, the adjustment based on the crozierpynten relation works better for depot point than the adjustment based on rijpfjorden: the annual average bias is 2.1 °c when using the relation based on the rijpfjorden relation and only 0.4 °c when using the crozierpynten relation. the 1935/36 observations at depot point on the north-west coast of nordaustlandet are thus apparently more in line with the observations at crozierpynten than with those at rijpfjorden, which is further east and further inland. the annual average temperature bias between the adjusted murchisonfjorden series and the svalbard airport series for 1957/58 is 0.2 °c when based on the crozierpynten relation.   table 5 validation of the linear relation between svalbard airport temperatures and rijpfjorden (2014–16) or crozierpynten (2010–12), respectively, using independent historic observations. shown is the monthly and annual mean temperature bias in °c between the scaled observations at nordaustlandet (rijpfjorden, depot point or murchi-son bay [murchisonfjorden]) and the extended svalbard airport series. jan feb mar apr may jun jul aug sep oct nov dec ann. rijpfjorden 1934/35, based on relation between svalbard airport and rijpfjorden (2014–16) −4.6 −5.4 −1.2 1.9 3.8 3.1 2.1 1.8 −1.1 0.4 −0.6 −2.7 −0.2 depot point 1935/36, based on relation between svalbard airport and rijpfjorden (2014–16): 0.9 2.2 4.0 3.5 2.1 3.1 2.9 1.4 2.7 0.3 0.2 1.9 +2.1 depot point 1935/36, based on relation between svalbard airport and crozierpynten (2010–12) −1.1 0.5 1.4 −0.1 −0.5 2.7 0.3 0.0 2.1 −0.4 −1.4 1.6 +0.4 murchison bay 1936, based on relation between svalbard airport and crozierpynten (2010–12) −0.1 2.8 1.0 murchison bay 1957/58, based on relation between svalbard airport and crozierpynten (2010–12) −1.0 −1.1 0.9 0.3 0.3 2.1 −0.4 0.3 0.9 −0.8 −0.4 1.7 +0.2 figure 4 shows the relation between the daily rijpfjorden measurements and the corresponding temperatures from the svalbard airport series for december to march for 1934/35 and 2014–16. the regression line based on the 2014–16 data is included for reference. we see that for temperatures down to about −15 °c, the 2014–16 regression also holds for the 1934/35 observations, but for lower temperatures, the 1934/35 rijpfjorden observations are often significantly colder than expected from the present-day regression. in fact, all data can be fitted reasonably well by a second order polynomial that agrees with the linear regression for temperatures above −15 °c. it therefore appears that for particularly cold conditions during winter the local temperatures at rijpfjorden fall below what is expected from the linear regression, possibly as a result of the occurrence of local boundary-layer inversions that effectively decouple the local temperatures from the larger-scale variations. the use of a non-linear (second order polynomial) relation between local and primary time series is, however, problematic in that it cannot be applied to monthly mean data and is prone to unrealistic results for data outside of the fitting range. consequently, all adjustments here are based on linear relations only. fig. 4 relation between rijpfjorden and svalbard airport temperatures during the winter months december to march. the dashed line is a second-order polynomial fit through all data points (1934/35 and 2014–16), and the solid line represents the linear fit to the 2014–16 data only. the occurrence of boundary-layer inversions is further analysed by looking at the haudegen radiosondes at rijpfjorden 1944/45. figure 5 presents the correlation between surface temperatures and 850 hpa radiosonde temperatures (roughly 1200 m altitude). surface temperatures are generally highly correlated with free tropospheric temperatures at 850 hpa. for winter temperatures below about −15 °c, two distributions emerge. for one distribution, surface temperatures still follow the correlation with 850 hpa temperatures with about the same lapse rate between the surface and 850 hpa. in particular, many of the coldest temperatures in winter 1944/45 are also associated with very cold conditions at 850 hpa. for the other distribution, however, we see that the surface temperatures are substantially colder—by about 10 °c—than expected from the 850 hpa temperatures, associated with a boundary-layer inversion. we may, therefore, speculate that the frequent occurrence of very low temperatures experienced by knoph and rudi in rijpfjorden in 1934/35 is associated with those conditions of boundary-layer inversions. these boundary-layer inversions are either less frequent in later periods or they are more pronounced in the inner rijpfjorden than at coastal sites. for example, liljequist (1959) reports that one of their scientific objectives was to study boundary-layer inversions during winter but because of the proximity to open water during winter 1957/58 at murchisonfjorden, inversions were not well established and, in many cases, did not exist at all. fig. 5 rijpfjorden 1944/45 surface temperatures against 850 hpa temperatures from radiosonde launches. only a few of the low surface temperatures in winter are associated with boundary-layer inversions. generally, surface temperatures are strongly correlated with 850 hpa temperatures (r2 = 0.79). conclusions and outlook the regression of the rijpfjorden aws with the svalbard airport temperature observations allows us to connect the 1944/45 haudegen observations to the extended svalbard airport series. this fills at least part of the gap in the svalbard airport series during world war ii. the quality of the regression using the rijpfjorden observations and the associated errors are comparable to the regression for crozierpynten or the other remote temperature series used by nordli et al. (2020). however, during the summer months, the correlations are poor and the adjustment should be used with caution. other available historic observations for nordaustlandet can be used to validate this adjustment approach. monthly mean temperature differences are comparable to what is expected from the rmse of the regressions and are very small in the annual average but can be up to a few degrees for individual months. comparisons of the oxford university expedition data set at depot point and the kinnvika data set indicate that these observations are more representative for the conditions at crozierpynten than for the rijpfjorden area in central nordaustlandet. to the best of my knowledge, the rijpfjorden observations in 1934/35 are discussed here for the first time in the scientific literature. although some doubts remain about the quality of this data set, these observations indicate that winter temperatures in the rijpfjorden area in 1934/35 were much colder than experienced by haudegen 1944/45 or in the 21st century. this could possibly be explained by more frequent boundary-layer inversions. the haudegen radiosonde observations generally show a strong correlation between surface temperatures and free tropospheric temperatures at 850 hpa. the lowest temperatures in winter were in many cases not restricted to the surface layer but extended up to the free troposphere. in some cases, however, surface temperatures were substantially lower than expected from the 850 hpa observations, related to the occurrence of a boundary-layer inversion. overall, the generally high correlation of surface with 850 hpa observations provides further confidence that the haudegen observations in 1944/45 are generally not restricted to local conditions but may be regarded as being representative of a larger region, justifying their use to complement the extended svalbard airport time series. the ultimate goal of filling the gap in the svalbard airport series associated with world war ii would be to retrieve any meteorological observations from the longyearbyen area during 1941–45. meteorological observations were made by norwegian and allied operations (elbo 1952; selinger & glen 1983), but whether any of these original data still exist is unclear. similarly, it would be very useful if any of the original daily temperature observations of the oxford university expedition in 1935/36 or the kinnvika expedition in 1957/58 could be retrieved, as well as any additional temperature observations in nordaustlandet in more recent decades. this would help to place the earlier observations at rijpfjorden into a longer-term context and to better characterize climate change in this data-sparse high-arctic environment. acknowledgements the rijpfjorden aws data were provided by unis. the author thanks marius jonassen for his help. crozierpynten aws data and the extended svalbard airport series were obtained from the norwegian meteorological institute through eklima.met.no. susan strahan (us national aeronautics and space administration’s goddard space flight center/universities space research association) advised on some points of language, and øyvind nordli (norwegian meteorological institute) and one anonymous reviewer provided helpful comments on the manuscript. the map in fig. 1 is based on the norwegian polar institute’s map website, toposvalbard. references ahlmann h.w., eriksson b.e., ångström a. & rosenbaum l. 1933. scientific results of the swedish–norwegian arctic expedition in the summer of 1931. part iv–viii. geografiska annaler 15, 73–216, doi: 10.2307/519460. bengtsson l., semenov v.a. & johannessen o.a. 2004. the early twentieth-century warming in the arctic—a possible mechanism. journal of climate 17, 4045–4057, doi: 10.1175/1520-0442(2004)017<4045:tetwit>2.0.co;2. blyth j.d.m. 1951. german meteorological activities in the arctic, 1940–1945. polar record 6, 185–226, doi: 10.1017/s0032247400040596. brönnimann s., grant a.n., compo g.p., ewen t., griesser t., fischer a.m., schraner m. & stickler a. 2012. a multi-data set comparison of the vertical structure of temperature variability and change over the arctic during the past 100 years. climate dynamics 39, 1577–1598, doi: 10.1007/s00382-012-1291-6. dege w. 1960. wissenschaftliche beobachtungen auf dem nordostland von spitzbergen 1944–1945. (scientific observations on spitsbergen’s nordaustlandet 1944–1945.) berichte des deutschen wetterdienstes 72. offenbach, germany: deutscher wetterdienst. dege w. 2004. war north of 80: the last german arctic weather station of world war ii. boulder: university press of colorado. dege w. 2006. gefangen im arktischen eis: wettertrupp “haudegen”—die letzte deutsche arktisstation des zweiten weltkrieges. (captured in the arctic ice: weather troop “haudegen”—the last german arctic weather station of world war ii.) hamburg: convent. elbo j.g. 1952. the war in svalbard, 1939–1945. polar record 6, 484–495, doi: 10.1017/s0032247400047276. fyfe j.c., von salzen k., gillet n.p., arora v.k., flato g.m. & mcconnell j.r. 2013. one hundred years of arctic surface temperature variation due to anthropogenic influence. scientific reports 3, article no. 2645, doi: 10.1038/srep02645. glen a.r. 1937. the oxford university arctic expedition, north east land, 1935–36. the geographical journal 90, 193–222, doi: 10.2307/1787611. glen a.r. 1939. the glaciology of north east land. geografiska annaler 21, 1–38, doi: 10.1080/20014422.1939.11880668. glen a.r. & croft n.a.c. 1937. under the pole star—the oxford university arctic expedition, 1935–6. london: methuen. grant a.n., brönnimann s., ewen t., griesser t. & stickler a. 2009. the early twentieth century warm period in the european arctic. meteorologische zeitschrift 18, 425–432, doi: 10.1127/0941-2948/2009/0391. hamilton r.a. 1938. the oxford expedition to north east land, 1935–36. general meteorology. quarterly journal of the royal meteorological society 64, 241–252, doi: 10.1002/qj.49706427504. hamilton r.a. 2012. arctic journal northeastland (nordhauslandet [sic]) 1935–36. norfolk, uk: salt publishing. knoph g.k. 1945. rypefjorden 1934/35. nordaustlandet, svalbard. handwritten journal accessed on the internet at https://brage.npolar.no/npolar-xmlui/handle/11250/2426467 on 21 july 2020 liljequist g.h. 1959. murchison bay—den svensk–finsk–schweiziska expeditionen till nordostlandet 1957–58. (murchison bay—the swedish–finnish–swiss expedition to nordaustlandet 1957–58.) ymer 79(2), 81–139. liljequist g.h. 1960. arktisk utpost—berättelsen om den svensk–finsk–schweiziska expeditionen till nordaustlandet 1957–1958. (arctic outpost—the story of the swedish–finnish–swiss expedition to nordaustlandet 1957–58.) stockholm: forum. nordli ø., przybylak r., ogilvie a.e.j. & isaksen k. 2014. long-term temperature trends and variability on spitsbergen: the extended svalbard airport temperature series, 1898–2012. polar research 33, article no. 21349, doi: 10.3402/polar.v33.21349. nordli ø., wyszynski p., gjelten h.m., isaksen k., łupikasza e., niedźwiedź t. & przybylak r. 2020. revisiting the extended svalbard airport monthly temperature series, and the compiled corresponding daily series 1898–2018. polar research 39, article no. 3614, doi: 10.33265/polar.v39.3614. pohjola v.a., kankaanpää p., moore j.c. & pastusiak t. 2011. the international polar year project ‘kinnvika’—arctic warming and impact research at 80° n. geografiska annaler, series a 93, 201–208, doi: 10.1111/j.1468-0459.2011.00436.x. przybylak r. 2000. temporal and spatial variation of air temperature over the period of instrumental observations in the arctic. international journal of climatology 20, 587–614, doi: 10.1002/(sici)1097-0088(200005)20:6<587::aid-joc480>3.0.co;2-h. przybylak r. 2007. recent air-temperature changes in the arctic. annals of glaciology 46, 316–324, doi: 10.3189/172756407782871666. przybylak r., araźny a., nordli ø., finkelnburg r., kejna m., budzik t., migała k., sikora s., puczko d., rymer k. & rachlewicz g. 2014. spatial distribution of air temperature on svalbard during 1 year with campaign measurements. international journal of climatology 34, 3702–3719, doi: 10.1002/joc.3937. przybylak r. & wyszynski p. 2020. air temperature changes in the arctic in the period 1951–2015 in the light of observational and reanalysis data. theoretical and applied climatology 139, 75–94, doi: 10.1007/s00704-019-02952-3. przybylak r., wyszynski p., nordli ø. & strzyżewski t. 2016. air temperature changes in svalbard and the surrounding seas from 1865 to 1920. international journal of climatology 36, 2899–2916, doi: 10.1002/joc.4527. przybylak r., wyszynski p. & woźniak m. 2018. air temperature conditions in northern nordaustlandet (ne svalbard) at the end of world war ii. international journal of climatology 38, 2775–2791, doi: 10.1002/joc.5459. rossnes g. 1993. norsk overvintringsfangst på svalbard 1895–1940. (norwegian overwintering harvest in svalbard 1895–1940.) meddelelser 127. oslo: norwegian polar institute. selinger f. & glen a. 1983. arctic meteorological operations and counter-operations during world war ii. polar record 21, 559–567, doi: 10.1017/s0032247400021963. stocker t.f., qin d., plattner g.k., tignor m., allen s.k., boschung j., nauels a., xia y., bex b. & midgley b. (eds.) 2013. climate change 2013: the physical science basis. contribution of working group i to the fifth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. wood k.r., overland j.e., jónsson t. & smoliak b.v. 2010. air temperature variations on the atlantic–arctic boundary since 1802. geophysical research letters 37, l17708, doi: 10.1029/2010gl044176. xiao h., zhang f., miao l., liang x.s., wu k. & liu r. 2020. long‑term trends in arctic surface temperature and potential causality over the last 100 years. climate dynamics 55, 1443–1456, doi: 10.1007/s00382-020-05330-2. yamanouchi t. 2011. early 20th century warming in the arctic: a review. polar science 5, 53–71, doi: 10.1016/j.polar.2010.10.002. analysis of satellite measurements of ozone, nitrous oxide and methane: intra-annual variations in the stratosphere aleksandr n. g r u z d e v and i g o r i. mokhov gruzdev, a . n. & mokhov, i. i. 1994: analysis of satellite measurements of ozone, nitrous oxide and methane: intra-annual variations in the stratosphere. polar research 13, 13-22. peculiarities in the intra-annual variations of 0,. n 2 0 and chi in the middle and upper stratosphere are analyscd by different methods for the middle and polar latitudes of the northern and the southern hemispheres. i n the middle stratosphere the phase of the 0, annual harmonic shifts in the northern hemisphere from polar to lower latitudes, while in the southern hemisphere the downward shift is exhibited. the phase of the n 2 0 annual harmonic shifts t o the poles both in the northern and southern hemispheres, but in the northern hemisphere it is almost vertical with the horizontal spreading, while in the southern hemisphere the phase propagation has a remarkable downward component. the most similar shifts of the phase of the annual harmonic in the middle stratosphere of both hemispheres are exhibited for the ch4 content in the middle and high latitudes. remarkable differences are noted between the intervals with the increase of mixing ratios in the annual cycle at different latitudinal belts. in particular, these intervals are large in subtropical stratosphere, with a shorter and steeper decrease of the mixing ratios. the general decrease of these intervals is exhibited from middle to polar latitudes. the striking difference in temporal variations of the species exists between the northern polar and middle latitudes, where the month-to-month changes of the species are often opposite each to other. these peculiarities and interhemispheric differences are associated with the different stratospheric dynamics of the northern and southern hemispheres, particularly with different regimes of planetary wave activity in the northern and southern extratropical latitudes. aleksandr n . gruzdeu and lgor i . mokhou, institute of atmospheric physics, russian academy of sciences, pyzheusky per. 3, moscow 109017, russia. introduction previous studies of the intra-annual variability in vertical distribution of ozone (03), nitrous oxide ( n 2 0 ) and methane (ch4) have been made by wilcox et al. (1977), jones & pyle (1984), gray & pyle (1986), solomon et al. (1986), holton & choi (1988), sun & leovy (1990) and gruzdev et al. (1991). all three species are well observable from satellite. the annual and semiannual har monics are known to be main contributors to the annual cycles of the species (gruzdev & mokhov 1988; holton & choi 1988). although having different origins and different spatial and tem poral distributions, these species have fairly long lifetimes (especially chi) to be tracers of the transfer processes in the stratosphere. the aim of this paper is a joint analysis of intra-annual variations of the three species on a global scale, with emphasis on features of their behaviour in polar regions. note that behaviour of n20 and chi at polar latitudes has not been analysed in previous studies. data and methods monthly mean, zonal mean satellite data for the middle and upper stratosphere (above 20 mb, approximately 28 km) are analysed. the data are the four year (1978-1982) nimbus 7 lims, nim bus 7 sbuv and ae-2 s a g e ozone measure ments in the latitude band of 80 n to 80 s reported by keating & young (1985), and the three year (1979-81) nimbus 7 sams measurements of n 2 0 and ch4 in the latitude band of 70n to 5 0 s reported by taylor et al. (1987). for the analysis of the intra-annual evolution of o3;n20 and ch4 in the middle and upper stratosphere, different methods of analysis are used. one is the standard harmonic analysis which makes the decompo sition of a complicated annual cycle into the linear superposition of the annual harmonic, the semi annual harmonic, and so on. although characterisation of separate har monics (by their amplitudes and phases) is suf ficient for knowing not only the integral but also the local (in time) behaviour of harmonics, it is 14 a. n. gruzdeu & i. i. mokhov not a simple matter in the case of the complicated annual cycle. the presence of two (or more) harmonics in an annual cycle can make it asym metric. moreover, the behaviour of separate har monics is not always associated with separate mechanisms. for an analysis of complicated cycles in atmospheric species’ fields the special method of amplitude and phase characteristics can be used (mokhov 1985). useful characteristics of the asymmetry of the annual cycle are the interval of increase with the positive time derivative and the interval with the exceeding of the local annual mean values (mixing ratios). these intervals are integral characteristics of the annual cycle, while the harmonic analysis displays the behaviour of separate harmonics, which is only a part of the common behaviour (gruzdev & mokhov 1988). more detailed characteristics of the intra annual evolution of atmospheric components are exhibited by the intermonth variations. here the month-to-month changes (mmcs) of mixing ratios (i.e., the differences between the mixing ratios for two successive months: the latter value minus the former value) will be used. the mmcs are very useful, as they give information on gov erning processes through the continuity equation. results the latitude-height cross sections of the february ozone mixing ratios (ozone annual cycle is incom plete with winter data at the southern polar lati tudes) and the mean square deviation of the ozone annual cycle, correspondingly, can be seen in fig. 1a and b. fig. 2a and b and fig. 3a and b show the annual mean mixing ratios of nzo and ch4 as well. note that in fig. 1b and in figs. 2 and 3 the coverage is asymmetric about the equator. according to fig. 1b the ozone annual cycle has amplitude maxima in the upper and middle stratosphere at high and middle latitudes of both the northern hemisphere (nh) and southern hemisphere (sh). the maxima are noted approximately above and below the maximum in ozone vertical distribution (cf. fig. 1a). the significant feature of the n 2 0 and ch4 intra annual variability is exhibited in figs. 2b and 3b by the two low-latitude maxima and the minimum at the nh middle latitudes at constant pressure surfaces. both the n 2 0 and ch4 mixing ratios decrease with height ( n 2 0 decreases more rapidly) and have low-latitude maximum at con stant pressure surfaces. fig. 4 shows the phases (time of maximum) of the annual and semiannual harmonics of 0,; figs. 5 and 6 show those of nzo and ch4. these figures include the nh polar latitudes compared with similar analysis by holton & choi (1988). it is also worth noting that we use the data modified compared with those used by holton & choi (1988). the maximum of the ozone annual har monic appears in the middle stratosphere above the northern and southern polar regions in appro priate spring (fig. 4a). in the nh middle strato sphere the o3 annual harmonic propagates from polar to lower latitudes, while in the sh the downward phase propagation occurs, with equat or-ward component at middle latitudes. the max ima of both the n 2 0 and ch4 annual harmonics appear at the nh polar latitudes in late spring (figs. 5a and 6a). both phases propagate from tropical to polar latitudes. propagating to the south, the phases move simultaneously down in the sh extratropical latitudes. in the nh extra tropical latitudes, however, the propagation of the phase of the ch4 annual harmonic has less downward component, and the phase of the nzo annual harmonic propagates t o the north without downward component. moreover, the tendency of upward n 2 0 phase propagation in the high latitude middle stratosphere is seen. the phases of the semiannual harmonics of all three species propagate downward above the tropics (figs. 4b, 5b and 6b), thus following the propagation of the regime of the well-known semiannual oscillation of the equatorial zonal wind (gray & pyle 1986; holton & choi 1988). in the nh high latitudes, equator-ward propa gation of the phase of the semiannual harmonic of o3 occurs in the middle stratosphere, and equator-ward propagation of the phases of the semiannual harmonics of n 2 0 and ch4 occurs in the upper stratosphere. the largest intervals of increase for n2o and ch4 (up 8 months and larger) are exhibited in the subtropical stratosphere. the annual cycles of these components are characterised there by a shorter and steeper decrease of the mixing ratios with longer intervals of relatively slow increase. the stratospheric layers with a large intervals of increase are displayed in subtropical latitudes for the ozone content too. there is also general decrease of these intervals from middle to polar latitudes with a shorter and steeper increase of the mixing ratios in the annual cycle. fig. 7 shows the altitude-time cross-sections of analysis of satellite measurements 15 --.50 8on 60 4 0 20 0 20 4 0 60 80s e x latitude latitude fig. i. latitude-height cross sections of (a) the 0, mixing ratios (ppmv) in february and (b) the mean square deviation of the o3 annual cycle (ppmv). -2010 n t i i 20 200 \ _ 60n 40 20 0 20 40s 60n 40 20 0 20 405 latitude latitude fig. 2. latitudc-height cross sections of (a) the annual mean n20 (ppbv) and (b) the mean square deviation of the n20 annual cycle (ppbv). a i / 1 .2 . 1 60n 40 20 0 20 40s latitude fig. 3. as in fig. 2 but of ch4 (ppmv). latitude 16 a . n. gruzdeu & i . i . mokhou a b . -, . . .5 1 2 e t .5 5 10 i i 2 0 -12 -30 30 2 0 ' eon 60 4 0 2 0 0 2 0 4 0 6 0 s eon 60 4 0 2 0 0 2 0 4 0 6 0 s latitude fig. 4. the phase (time of maximum, month) of ( a ) the annual and (b) semiannual harmonics of 0, latitude .5 50 50 1 6i e y e 2 x 2 '0 4 0 4 0 a 3 u) e e .a 5 f a q 10 20 30 3 0 60n 4 0 20 0 2 0 40s 60n 4 0 20 0 20 40s latitude latitude fig. 5. as in fig. 4 but of n20. l" 60n 40 2 0 0 20 4 0 s latitude fig. 6. as in fig. 4 but of chi. latitude analysis of satellite measurements 17 a b month month c d 1 3 5 7 9 1 1 1 month month fig. 7. altitude-time cross sections of month-to-month changes of 0, (ppmv/month) at ( a ) 7 0 n , (b) son. (c) 70s and (d) 50s. the mmcs of the o3 mixing ratios at 70n, 50n, 70s and 50s. figs. 8 and 9 show the mmcs of the n 2 0 and ch4 at 70n, 50n and 50s. zero lines in the figures correspond to local time extrema (maxima or minima). the ozone annual cycle in the sh extratropical latitudes is characterised by opposite ozone changes in the upper and middle stratosphere during almost the entire year, except spring (fig. 7). unlike in the sh, opposite ozone changes in the upper and middle stratosphere in the nh extratropical latitudes are only seen in summer, in winter ozone increases at all altitudes. in spring the ozone increase continues in the middle stratosphere of the nh high latitudes, while in the upper stratosphere the process of increase is changed to the process of decrease. this causes the regime of maximum ozone mixing ratios to propagate downward in late winter to spring (see zero isoline in fig. 7a). a similar feature of the downward propagation of the maxi mum values of ozone mixing ratios is also seen in spring at the nh middle latitudes (fig. 7b) and the sh high latitudes (fig. 7c). note that the semiannual variation is more evident in the upper stratosphere in the nh extratropical latitudes than in the sh extratropical latitudes. distinct semiannual variations (and, sometimes, variations of higher frequencies) are seen in the n 2 0 mmcs as well (fig. 8). it should be noted that although the semiannual harmonic does not dominate in the annual cycles of the species in the most parts of the stratosphere, the strength of increase and decrease processes is often of the same order for different increase and decrease episodes (but duration of the episodes can be different, see figs. 7 and 8). the n 2 0 annual evolution at 70n (fig. 8a) is characterised by a strong increase in the mixing ratios during winter and early spring but by decrease during the rest of year (except the two short-term increase episodes in summer and autumn). a t lower levels the decrease is seen in mid-winter. note that the spring maximum propagates from top to bottom. at 50n (fig. 8b) 18 a. n. gruzdeu & i . i . mokhou the winter increase is still retained above 10 mb, but at lower levels it changes into a strong decrease. the decrease continues throughout the considered stratosphere till summer and then changes into increase, which is followed by the autumn decrease. the mmcs at 50s show certain similarities to that at 50n (after six month shift). however, there is an important difference: at 50n the n 2 0 increase above 1 0 m b occurs in mid winter, while at 50s the similar increase occurs in early spring. the ch4mmcs in the upper stratosphere (fig. 9) are in qualitative agreement with the n 2 0 mmcs, although there are large quantitative dif ferences there. a great difference is seen between the n 2 0 and ch4 mmcs at low levels. this will be discussed below. fig. 10 shows the latitude-time cross sections of the ozone mmcs at 3 m b and 1 5 m b cor respondingly. the mmcs i n the extratropical lati tudes of the two hemispheres at 3 mb are roughly anti symmetric (or symmetric because of the pres ence of the semiannual variation) about the equa tor, with periods of increase during mid-winter to mid-spring and during mid-summer to mid autumn, and with a decrease during the rest of a year. at higher levels, however (for example, at the 1.5mb level, not shown, where the ozone mmcs have maximum values in the upper strato sphere; see fig. 7), the ozone mmcs in the extra tropical latitudes of the two hemispheres becomes asymmetric: unlike in the nh, there is no any winter-to-spring ozone increase there in the sh. at the lower level, at 15 mb, the ozone mmcs in the extratropical latitudes are roughly anti symmetric about the equator (fig. 10b). there are important interhemispheric differences, how ever, especially at high latitudes. first, in the northern polar region the ozone content increases during the winter period, while in the southern polar region the increase occurs in spring. the' lag of the ozone increase process at the polar latitudes relative to the lower latitudes is also exhibited. second, the distinctive difference in ozone springtime evolution is noted in the nh between the polar and middle latitudes: ozone continues t o increase in the middle latitudes, but decreases in the polar region. such opposite changes in the nh polar and middle latitudes are also seen in fig. 7a and b. in the sh the similar feature, but of shorter duration and less intensity, is noted in early summer. besides, the boundary between the opposite ozone changes shifts in the a month b 1 3 5 7 9 1 1 1 month c month fig. 8. altitude-time cross-sections of month-to-month change of nzo (ppbv/month) at ( a ) 70n, ( b ) 50n. and (c) 50s. sh t o the lower latitudes (fig. 10b) so that ozone variations in the southern polar region and at the adjacent latitudes are synchronous. figs. 11 and 12 show the latitude-time cross sections of the mmcs of n 2 0 and ch4 at 3 mb and 15 mb, correspondingly. the important feature in figs. 11a and 12a is roughly symmetric patterns of isolines about the nh and sh subtropical latitudes during the period of the appropriate spring to autumn. the n20 increase, originating in the nh tropics in may, propagates during the following four months to the north and to the south. a similar propagation from the sh tropics is seen for the increase in the sh spring. however, during november to january the fast counter propagation from the nh high latitudes is seen, while no similar counter propagation is evident from august to september in the sh middle latitudes. the n2o mmcs at 15mb (fig. 11b) are roughly antisymmetric about the equator, with summer and autumn increase, and winter and spring decrease at middle latitudes. however, there is an important inter-hemispheric differ ence. the regime of the strongest increase in the nh has a tendency to propagate from the equator to the high latitudes, while this is not the case in the sh. this discrepancy is reflected in the phase dynamics of the annual harmonic in fig. 5a. the important feature in fig. 11b is also the opposite changes of n 2 0 at the high and middle latitudes of the nh. the mmcs of ch4 at the 1 5 m b level (fig. 12b) differ strongly from the mmcs of n20 (fig. 11b). rather the mmcs of chi at 15mb resemble the mmcs of ch4 at 3 rnb (after about a 6 month shift), with essential differences in the sh, however, where the mmcs at 15 mb do not possess symmetry about the sh subtropical lati tudes. note that the regime of the autumn increase of chi at 15 mb in the sh propagates from the low to middle latitudes. in the nh similar propagation is less evident. this inter hemispheric difference is also reflected in the different rates of propagation of the phase of the annual harmonic in the nh and sh middle latitudes in fig. 6b. discussion the analysis made has revealed specific features in the annual cycles of 03, n20 and ch4 in the stratosphere. the key to these features lies in knowing the circulation and photochemical pro cesses. solomon et al. (1986) and holton & choi (1988) have shown that the diabatic circulation or the effective transport circulation explain main features of nzo and ch4 in the tropics and in the summer hemisphere. these circulations are qualitatively similar in that the solstices' upward velocity in the summer hemisphere and downward velocity in the winter hemisphere dominate. however, these two types of circulation are not adequate for describing transport of the species in winter and in spring, when transience of planetary waves has to be taken into account. it is well known that transient waves play an important analysis of satellite measurements 19 a month month c 5 0 e y 0, 0 40 .z 4 30 5 0 e y 0, 0 40 'z 4 30 monlh fig. 9. as in fig. 8 but of ch4 (ppmv/rnonth). role in transporting species (see e.g. plumb 1979; kurzeja 1983). features of the n 2 0 and ch4 mmcs seen in figs. 8 and 9 are reflected in the effective transport velocity field deduced by holton & choi (1988), so that decrease of mixing ratios usually occurs with downward transport and increase with upward transport (at subtropical latitudes hori 20 a . n. gruzdev & i . i . mokhou a b month month fig. 10. latitude-time cross sections of month-to-month changes of 0, (ppmv/month) at (a) 3 mb and ( b ) 15 mh a 1 3 5 7 9 1 1 1 month fig. 11. as in fig. 10 but of n20 (ppbv/monlh). b 1 3 5 7 9 11 1 month a b 1 3 5 7 9 11 1 1 3 5 7 9 1 1 1 month fig. 12. as in fig. 10 but of ch,. month analysis of satellite measurements 21 zontal transport can also affect the mixing ratios). the behaviour of the n 2 0 and ch4 mixing ratios in the middle stratosphere at the nh high lati tudes differs from that at the middle latitudes, being often the opposite (figs. 11b and 12b). these opposite changes could be understood if one assumes the existence of a high latitude cir culation cell. the n 2 0 and ch4 mmcs in the nh high latitude middle stratosphere, in winter for chi (fig. 12b) but only from february to march for n 2 0 (fig. 11b). are consistent with such a circulation but require the subsiding arm of the circulation to be placed at middle latitudes. note, however, that neither the effective transport cir culation nor the residual mean circulation has any feature similar to this cell. from summer t o autumn the mmcs of nzo and ch4 in the middle and high latitudes of the nh middle stratosphere are often opposite to each other, but have positive values in the middle latitudes and negative values in the high latitudes. this discrepancy can be associated with the regime of the mixing ratio increase (due to upward motion in the summer hemisphere) propagating from the tropics (figs. 11a and 12a), while at the high latitudes the decrease which began in spring continues (due to photochemical loss?). all these deductions are hypothetical and should be verified by calculations. essential interhemispheric differences in n 2 0 and ch4 intra-annual variations have already been mentioned. the interhemispheric difference in phase characteristics in the middle stratosphere is particularly striking (figs. 5 and 6). big down ward component in phase propagation of both the annual and semiannual harmonics in the sh extratropical latitudes, but rather horizontal propagation in the nh extratropical latitudes, are likely due to the predominant role of the residual meridional circulation in transporting the species in the sh winter stratosphere, while in the nh winter stratosphere, with its greater planetary wave activity, the horizontal eddy mixing is also important. the difference between n20 and ch4 behav iour is also important. although both species are produced in the troposphere and have potentially fairly long lifetimes as good tracers, they differ in the distribution and strength of sources as well as in altitude and latitude dependence of lifetimes. this results in different features of spatial dis tributions of n 2 0 and ch4 and their variations, particularly in high latitudes. characteristics of annual cycles of n 2 0 and ch4 may therefore also be different because various circulation and photochemical mechanisms are displayed dif ferently in n20 and chi evolution. ozone has a quite different spatial distribution and a shorter photochemical lifetime, especially in the upper stratosphere, than n 2 0 and ch4. nevertheless, ozone intra-annual variations are generally in agreement with variations of n20 and ch4 in that they reflect the same dynamical processes. opposite ozone changes in the upper and middle stratosphere in the two hemispheres in summer (fig. 7) imply upward motions (cf. fig. 1a). similar opposite ozone changes (but of reversed sign) are realised in winter in the sh only. they could be related to downward motions. quite different ozone behaviour in the nh in winter is associated with the horizontal pole-ward trans port of ozone by planetary waves. such a trans port results in the winter-to-spring ozone increase seen in fig. 7a and b and fig. 10a and b. the effect of horizontal pole-ward transport of ozone is also seen in the sh, but o n l y during the rela tively short period in spring (fig. 7c and d and fig. 10a and b). moreover, in the upper strato sphere (at 1.5mb and higher), this effect dis appears in the sh, while the effect of the winter ozone increase in the nh is observed at least up to the 0.4 mb level. the striking interhemispheric difference in ozone intra-annual variations in the extratropical latitudes is known to be associated with the dif ference between the stratosphere dynamics of the nh and sh. it is manifested first of all as the interhemispheric differences in planetary wave activity. planetary waves have the largest ampli tudes during winter and through the spring in the nh, but only in the spring in the sh; moreover, they are about twice as intensive in the nh as in the sh (geller & wu 1987). in their contribution to the ozone flux divergences, the stationary waves dominate in the nh. in the sh the station ary and transient eddy divergences of the ozone flux are of the same order (geller et al. 1989). the stationary waves penetrate higher into the stratosphere in both hemispheres, however. this could explain the above-mentioned existence of the ozone increase in winter in the nh upper stratosphere and the absence of the similar increase in spring in the sh. the important role of horizontal eddy transport of ozone in the nh extratropical latitudes is also reflected in behaviour of the phase of the annual 22 a . n . gruzdev & 1. i . mokhov harmonic (fig. 5a), which is consistent with the phase behaviour in figs. 6a and 7 a (implying the horizontal component in phase propagation). the discrepancy between behaviours of middle stratosphere ozone i n the nh polar and middle latitudes (fig. 10b) is not understood. it could be explained if one suppose the existence of cir culation cell with arising motions over the pole and subsiding motions at the middle latitudes. besides, ozone fluxes due t o such a circulation should not be compensated by eddy fluxes, as occurs in the case of stationary waves (plumb & mahlman 1987). the transience of planetary waves in spring speaks in favour of non-com pensating effect. this should certainly be verified by calculations and/or observations. in any case, the effect of polar-mid-latitude difference in ozone variations is supported by the polar-mid latitude difference in n 2 0 and ch4 variations (see above). the peculiarities of the nh polar region are also seen in behaviours of the phases of the semi annual harmonics (figs. 4b, 5b and 6b). these are very likely not connected in any simple way to the tropical semiannual oscillation of zonal wind. the circulation associated with the tropical semiannual oscillation itself is likely to produce vertical motion in the extratropical latitudes (gray & pyle 1986). on the other hand, the forcing occurring in the extratropical latitudes in winter hemisphere affects the circulation over the tropics (solomon et al. 1986). alternatively, the semiannual variations of the species in the north ern polar region may be associated with the semi annual variation of planetary wave activity (geller c wu 1987). the question of semiannual variations of atmospheric species in extratropical latitudes needs further investigation. references geller, m. a. & wu, m. f. 1987: troposphere-stratosphere general circulation statistics. pp. 3-17 in g . visconty & r. garcia (eds.): transport processes in the middle atmos phere. d. reidel publishing company, dordrecht. holland. geller. m. a . & wu, m. f. & nash. e. 1989: satellite data analysis of ozone differences in the northern and southern hemispheres. pure appl. geophys. 130. 263-275. gray, l. j . & pyle, j . a. 1986: the semi-annual oscillation and equatorial tracer distributions. quart. j. r . met. soc. 112, 387-407. gruzdev, a. n.. karol. i . l . . kudryavtsev. a . p . , mokhov, 1. 1. & sitnov, s. a . 1991: peculiarities of polar ozone annual course: analysis of satellite and ozonesonde data and model results. norsk geolog. tihskr. 71, 183-187. gruzdev, a. n. & mokhov. 1. 1. 1988: diagnostics of strato spheric ozone dynamics in annual course from satellite data. issledovanie zemli iz kosmosa n 2, 3-10, holton, j. r . & choi, w.-k. 1988: transport calculation de duced from sams trace species data. j. armos. sci. 4 5 , 1 9 2 s 1939. jones, r. l. & pyle, j . a. 1984: observations of ch4 and n 2 0 by the nimbus 7 sams: a comparison with in situ data and two-dimensional numerical modcl calculations. j . geophys. res. 89, 5263-5279. keating, m. & young, d . f. 1985: interim reference ozone models for thc middle atmosphere. handbook for map 16. pp. 205-229. kurzeja, r. j . 1983: the transport of trace chemicals by plan etary waves in the stratosphere. part 2: transport of 0, and n 2 0 by transient waves. 1. armos. sci 40, 20362054, mokhov, i . i . 1985: method of amplitude-phase characteristics for analysis of climate dynamics. mereorol. hydrol. 5 , 14-23. plumb, r. a. 1979: eddy fluxes of conserved quantities by small-amplitude waves. j. afmos. sci. 36, 169%1704. plumb. r. a. & mahlman, j . d. 1987: the zonally averaged transport characteristics of the g f d l general circulation/ transport model. j , armos. sci. 44, 298-327. solomon, s., kiehl, j . t . , garcia, r. r. & grose, w. 1986: tracer transport by the diabatic circulation deduced from satellite observations. j. atmos. sci. 43, 1603-1617. sun, c.-r. & leovy, c. 1990: ozone variability in the equatorial middle atmosphere. j. geophys. res. 95, 13.829-13.849. taylor, f. w., dudhia, a . & rodgers, c. d. 1987: proposed reference models for nitrous oxide and methane in the middle atmosphere. a d v . space res. 7 , (9)49-(9)62. wilcox, r. w., nastrom, g . d. & balmont, a. d. 1977: periodic variations of total ozone and its vertical distribution. j. appl. meseorol. 16, 29&298. beluga whale stewardship and collaborative research practices among indigenous peoples in the arctic review article beluga whale stewardship and collaborative research practices among indigenous peoples in the arctic kaitlin breton-honeyman1, henry p. huntington2, mark basterfield1, kiyo campbell3, jason dicker4, tom gray5, alfred e.r. jakobsen6, frankie jean-gagnon1, david lee7, rodd laing4, lisa loseto8,9, paul mccarney4, john noksana jr3, tommy palliser1, lawrence ruben10, clayton tartak11, joseph townley4 & eduard zdor12 1nunavik marine region wildlife board, inukjuak, qc, canada 2ocean conservancy, eagle river, ak, usa 3fisheries joint management committee, inuvik, nt, canada 4department of lands and natural resources, nunatsiavut government, nain, nl, canada 5alaska beluga whale committee, nome, ak, usa 6oceans north greenland, nuuk, greenland 7department of wildlife and environment, nunavut tunngavik inc., ottawa, on, canada 8freshwater institute, fisheries and oceans canada , winnipeg, mb, canada 9environment and geography, university of winnipeg, winnipeg, mb, canada 10inuvialuit game council, paulatuk, nt, canada 11kivalliq wildlife board, nunavut inuit wildlife secretariat, rankin inlet, nu, canada 12university of alaska fairbanks, fairbanks, ak, usa abstract beluga whales (delphinapterus leucas) are an integral part of many arctic indigenous cultures and contribute to food security for communities from greenland, across northern canada and alaska to chukotka, russia. although the harvesting and stewardship practices of indigenous peoples vary among regions and have shifted and adapted over time, central principles of respect for beluga and sharing of the harvest have remained steadfast. in addition to intra-community cooperation to harvest, process and use beluga whales, rapid environmental change in the arctic has underscored the need for inter-regional communication as well as collaboration with scientists and managers to sustain beluga populations and their cultural and nutritional roles in arctic communities. our paper, written by the overlapping categories of researchers, hunters, and managers, first provides an overview of beluga hunting and collaborative research in seven regions of the arctic (greenland; nunatsiavut, nunavik, nunavut, and the inuvialuit settlement region, canada; alaska; and chukotka). then we present a more detailed case study of collaboration, examining a recent research and management project that utilizes co-production of knowledge to address the conservation of a depleted population of beluga in nunavik, canada. we conclude that sustaining traditional values, establishing collaborative management efforts, the equitable inclusion of indigenous knowledge, and respectful and meaningful collaborations among hunters, researchers and managers are essential to sustaining healthy beluga populations and the peoples who live with and depend upon them in a time of rapid social and environmental change. this article is part of the special cluster beluga whales (delphinapterus leucas): knowledge from the wild, human care and tek, which has been funded by mystic aquarium, caff and the norwegian ministry of climate and environment. keywords marine mammals; arctic; co-production of knowledge; wildlife research and management; delphinapterus leucas abbreviations cosewic: committee on the status of endangered wildlife in canada dfo: fisheries and oceans canada ehb: eastern hudson bay fjmc: fisheries joint management committee nilca: nunavik inuit land claims agreement nmrwb: nunavik marine region wildlife board tat: total allowable take whb: western hudson bay   citation: polar research 2021, 40, 5522, http://dx.doi.org/10.33265/polar.v40.5522 copyright: polar research 2021. © 2021 k. breton-honeyman et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 19 november 2021 competing interests and funding: the authors report no conflict of interest. no specific funding was used in the writing of this paper, beyond institutional support for some co-authors’ time. correspondence to: k. breton-honeyman, nunavik marine region wildlife board, po box 433, inukjuak, j0m 1m0 qc, canada. e-mail: kbretonhoneyman@polynyaconsulting.ca introduction the beluga whale (delphinapterus leucas) is found throughout the arctic and in some subarctic locations (hobbs et al. 2019; fig. 1). indigenous peoples in greenland, canada, alaska and chukotka (russia) regularly hunt beluga (meehan et al. 2017), a practice that has continued for centuries or longer, effectively since time immemorial (e.g., lucier & vanstone 1995). the role of beluga varies by community, from occasional part of the diet to the majority of the annual harvest of traditional foods (blanchet & rochette 2008; frost & suydam 2010; kenny & chan 2017; nammco 2018). beluga are also a popular symbol of the arctic and studied throughout their range (nammco 2018). the convergence of traditional practice in indigenous communities, assertion of indigenous harvesting and land rights, and widespread interest by the public, academia and government has given rise to collaborative management efforts (in some contexts formal co-management arrangements) in many regions. through such efforts, hunters, researchers, elders, and management officials work together to conserve beluga whale populations and sustain traditional harvests (table 1). table 1 approximate average annual beluga harvest by region in recent years (ca. five years). there is considerable inter-annual variability in some regions. (frost & suydam 2010; nammco 2018; hobbs et al. 2019; dfo unpubl. data; alaska beluga whale committee unpubl. data). region approximate annual harvest stocks harvested from greenland 200 eastern high arctic–baffin bay nunatsiavut < 5 unknown, possibly ehb or cumberland sound nunavik 300 ehb (65) james bay (10) whb (250) ungava bay (few if any) nunavut 400 cumberland sound eastern high arctic–baffin bay ehb whb inuvialuit settlement region 90 eastern beaufort sea alaska 300 bristol bay (20) eastern beaufort sea (40) eastern bering sea (190) eastern chukchi sea (60) chukotka 20 anadyr (2) eastern bering sea (20) fig. 1 seven regions of the arctic where indigenous peoples harvest beluga (greenland; nunatsiavut, nunavik, nunavut, and the inuvialuit settlement region, canada; alaska; and chukotka) and beluga distribution for summering areas (dark blue-green), and wintering and migratory areas (light blue-green) (hobbs et al. 2019). in this paper, whose authors are researchers, hunters, wildlife managers, or a combination thereof, we review indigenous stewardship practices and collaborative research efforts regarding beluga whales in the regions where these animals are hunted regularly. the two themes emerged from panel discussions at the second international workshop on beluga whale research and conservation, held in mystic, ct, in march 2019. specifically, indigenous participants spoke about the continuing importance of beluga hunting for indigenous identity and community well-being (“if you share your catch, your freezer will always be full”), and about the necessity in changing times of hunters working with scientists and managers to achieve what none can achieve alone (“we will need help”). the review begins with overviews from greenland; nunatsiavut, nunavik, nunavut, and the inuvialuit settlement region in canada; alaska; and chukotka, russia. the descriptions, by authors from each region, are based on extensive personal involvement in beluga hunting, research and management, supplemented by published literature where available. then, we take a closer look at beluga hunting and management in nunavik, canada, site of particularly entangled conservation concerns rooted in historical commercial harvesting and complicated by overlapping beluga populations with different conservation statuses. the nunavik case study was prepared by individuals affiliated with the nmrwb, who have had direct experience with all aspects of beluga whales in that region. we conclude with a discussion of the significance of beluga whale stewardship and research. while many of these topics have been addressed in numerous publications about different locales in the arctic, we are unaware of any recent effort to compile in one place the available information on beluga stewardship and collaborative research across the arctic region of indigenous beluga hunting. we believe there is much to learn from sharing experiences across regions and hope that our paper furthers self-determination in beluga stewardship and the persistence of harvesting practices and healthy beluga populations. regional harvest practices, traditional values and collaborations many regions share a similar history of hunting beluga quietly by groups in kayaks without the use of rifles (e.g., alayco et al. 2007). the sections below focus on more recent practices. although inuit and chukchi have adopted modern tools, such as rifles and motorized boats, they continue to hunt beluga whales with traditional technology such as the unaaq (the inuktitut term for the specialized beluga harpoon head and harpoon), which is attached to an avataq (float). the float not only slows the progress of the whale that can then be dispatched readily and humanely, but also permits retrieval of the whale, reducing the incidence of struck and lost whales. the regional overviews also discuss the degree to which beluga research is collaborative, giving examples of studies done through partnerships between indigenous communities and visiting researchers and managers. one noteworthy trend is the growing intellectual role of indigenous individuals as initiators and leaders of research efforts. table 2 provides a summary of the regional patterns. in these summaries, the contributors from each region have chosen what to emphasize, the indigenous terminology to include and how to describe hunting and research in their areas. as a result, a strict consistency among regional descriptions has taken second place to local authenticity and perspectives. table 2 traditional values, hunting and stewardship practice, management organization and approach and collaboration by region. region traditional values hunting and stewardship practices management body collaborationa greenland sharing respect harvesting from small boats or ice (kayaks or nets in qaanaaq) greenland self-rule government + harvest sampling nunatsiavut sharing respect harvesting from shore, boat, or sina (floe edge) depending on the season dfo ++ few research projects but most collaborative nunavik sharing of catch respect taking only what is needed avoiding wastage and noise harvesting from shore or boat depending on the season use of rifles, harpoons and heavy hooks kayaks historically avoiding harvest of lead whales estuary closures tat (ehb beluga) nmrwb: co-management ++ harvest sampling and some research projects nunavut inuit qaujimajatuqangit respect taking only what is needed sharing harvest in the fall (kivalliq region) closed harvest season in summer (ehb) total allowable harvest (cumberland sound) motor boats, high-powered rifles, unaaq and avataq (harpoon with float) kayaks historically nunavut wildlife management board: co-management ++ new community-based research projects inuvialuit settlement region respect for beluga sharing of catch cooperation hunting from small boats harpoon first avoid harvesting females community hunting by-laws management plan developed through co-management fjmc, inuvialuit game council: co-management +++ hunters involved in all current research projects more work on indigenous knowledge is needed alaska prohibition on waste respect for whales sharing of catch preparation for hunt conflict avoidance reduction of struck and lost harvesting from shorefast ice (spring) harvesting by boat (summer and fall) netting from shore (summer and fall) harpoon and rifles alaska beluga whale committee: co-management +++ hunters involved in many research projects hunters involved in identifying research priorities through the alaska beluga whale committee chukotka catch distributed among hunters and neighbours mainly spring and late fall usually from shore (summer) or shorefast ice (winter) rifle, harpoon and wooden or metal hook head returned to the sea federal government (general permit for hunting by the indigenous peoples of chukotka) the chukotka fisheries commission (government of the chukotka okrug) allocates the quota among villages. +some research projects, including biopsy sampling and satellite tagging a+ little collaboration, ++ moderate collaboration, +++ extensive collaboration. greenland beluga whales (qilalugaq qaqortoq) are hunted in greenland, from the baffin bay stock of beluga shared with canada (nammco 2018). the beluga harvest has varied in recent years from the low hundreds to a little above 300 animals. most are taken in west greenland, though some are hunted in qaanaaq and surrounding settlements in the north, including 105 taken in that region in 2019. hunting occurs in spring, summer and fall, from small boats or from the ice. in qaanaaq in particular, some hunting is done from kayaks or with nets (nammco 2021). current harvest levels are regarded as sustainable (heide-jørgensen et al. 2017); concerns about overhunting in the 1990s led to management efforts aimed at reducing the harvest to sustainable levels, including the introduction of overall quotas in 2004. the harvest has also been reduced because beluga are less available to hunters now that climate change has shifted the ice edge—the preferred habitat of the animals when they migrate to greenland in winter—farther from shore (heide-jørgensen et al. 2017). one result of the smaller harvest and changes in hunting practices has been that sharing practices have shifted to emphasize participation in the hunt rather than specific roles or actions; this is built on egalitarian principles but rewards larger boats with more participants (sejersen 2001). a further societal challenge is competition among ‘professional’ and ‘non-professional’ hunters regarding the allocation of the harvest quota, which may cause resentment and undermine the perceived legitimacy of the management system. beluga research in greenland has included aerial surveys (heide-jørgensen et al. 2010), genetic analysis (palsbøll et al. 2002) and satellite telemetry (richard et al. 2001). hunters have contributed samples for analysis (nammco 2021). thomsen (1993) documented knowledge from inuit hunters in western and northern greenland. hunters provide the government with detailed reports that include, for each catch, date and position, information about the hunting method and biological data such as age class, gender, size, reproductive state and stomach contents. this information is used in the assessments by the north atlantic marine mammal commission and the canada–greenland joint commission on narwhal and beluga (meehan et al. 2017). other than this, there has been little collaborative research involving hunters and scientists compared with canada and alaska. nunatsiavut, canada labrador inuit in nunatsiavut have traditionally hunted beluga (kilalugak) seasonally when whales came to the labrador coast. there is extensive reference to labrador inuit hunting various species of whales throughout the 17th and 18th centuries, including ‘white whales’ (brice-bennett 1977). brice-bennett (1977) mapped core areas of beluga in a number of areas throughout the outer islands along the labrador coast from the hopedale region to nachvak fjord. brice-bennett also describes that on the northward migration of beluga, during spring when the landfast ice began break-up, “[e]very year, the hunters shot a few white whales while waiting along the floe edge for seals. they had to harpoon the whales quickly before they sank, then haul them up on the ice, where they shared their meat and skin” (1977: 121). inuit also hunted beluga during june and july in hebron, saglek and nachvak fjords during calving and feeding times. taylor (1977) describes traditional historical seasonal movement patterns of labrador inuit. in spring, typically from mid-april to late june, historical records show that “[i]n several areas, walrus and white whales were also important. white whales were particularly important at avertok, kivertlok, kangerdluksoak, and naghvakh” (1977: 53). taylor & taylor (1977) describe spring and summer hunting of beluga in the okak region between 1776 and 1830. at present, beluga are not abundant around the five nunatsiavut communities (nain, hopedale, postville, makkovik and rigolet). few people in nunatsiavut actively and deliberately hunt beluga today and beluga do not form a large component of the labrador inuit wild food diet. changes in sea-ice conditions make it more difficult to hunt beluga during the spring season, when whales begin to arrive. during ice conditions that are likely favourable, inuit try to harvest beluga, most commonly in the hopedale region. beluga hunting remains a communal and social activity. hunters in nain and hopedale explain that some people still hunt beluga in larger groups while others go out in smaller groups of one or two other people. it is still a common practice to share the catch with the whole community after a successful hunt. people come to the water when a whale is brought in to take meat and blubber for their households. all nunatsiavut communities currently have community freezers that distribute wild meat to community members. when hunters have taken their share of a harvested beluga, the rest is delivered to the community freezer to share with the rest of the community. beluga numbers decreased along the labrador coast in the early 1900s, and by 1920 it was considered rare to see a beluga south of the torngat region (brice-bennett 1978). dfo records of beluga within the study area covered by mccarney et al. (2021) include a total of nine individuals and an additional single individual within 20 km of the study area in recent years. however, the low number of systematic surveys over time make it difficult to assess population trends. genetics research has been conducted in collaboration between dfo and the nunatsiavut government, with analysis ongoing (j. lawson, dfo, unpubl. data). samples for genetics analysis were provided by the nunatsiavut government. there is evidence to suggest that some of the beluga found along the labrador coast belong to the ehb population. telemetry work identified the hopedale saddle ecologically and biologically significant area as an important overwintering habitat for ehb beluga (lewis et al. 2009; bailleul et al. 2012a). the northern labrador ecologically and biologically significant area has also been identified as a unique migratory area for ehb beluga (dfo 2013). nunavik, canada all 14 nunavik communities harvest beluga (qilalugaq). beluga from four different summering groups—whb, ehb, ungava bay (where few beluga remain) and james bay—are locally accessible to communities at different times of the year and with varying abundance; however, many communities have to travel to access larger groups of beluga. hunting predominantly occurs along the spring and fall migratory routes of the whb and ehb beluga. during the summer, harvest rates decline in most of nunavik, with the exception of south-eastern hudson bay which is the summering area for the ehb stock. however, management restrictions and other factors keep harvest levels in this area relatively low. in areas where beluga travel close to the shore, hunting often takes place from the ice (in spring) or the shore (in fall) with the assistance of boats, harpoons and heavy hooks to retrieve whales. boats are commonly used in areas where beluga occur further offshore and during the summer. at present, the hunting method is to harpoon first, followed by the use of a rifle, with rare exceptions (e.g., in some areas beluga float in the spring and the water is shallow and clear, making the use of a harpoon unnecessary). regardless of the hunting method, practices such as sharing the catch, showing respect for the whale, not taking more than is needed and avoiding wastage govern beluga harvesting in all communities (alayco et al. 2007; tyrrell 2008). beluga are sensitive to noise, so traditional hunting practices also avoid noise disturbance. other practices, such as avoiding harvesting the lead whales during migration and avoiding females with calves, are followed by some hunters but management regulations and concerns over missed harvesting opportunities have altered some of these practices. beluga harvesting and management has a difficult history in nunavik. harvest quotas and other management measures were introduced in the 1980s in an effort to conserve ehb beluga (hammill et al. 2004). however, these management regulations were viewed by many nunavik inuit as forms of cultural imperialism, imposed from outside the region (tyrrell 2008) and widespread dissatisfaction remains. despite these issues, there is a long-standing and successful harvest sampling programme whereby hunters send samples to the regional research centre for studies such as population dynamics, diet, contaminants and genetics. aerial surveys, which have been repeatedly conducted since the 1980s (e.g., gosselin et al. 2017), together with genetics research, form the foundation of the current management model (turgeon et al. 2012; mosnier et al. 2017). a satellite tagging programme was conducted for only a limited amount of time (bailleul et al. 2012b), as many hunters are opposed to that method. no tagging has occurred in the region since 2004. several studies have documented inuit knowledge, which has been increasingly incorporated into management approaches and measures (doidge et al. 2002; lee et al. 2002; tyrrell 2007a; lewis et al. 2009; breton-honeyman, hammill et al. 2016). the formalization of co-management with the creation of nilca, which established the nmrwb, has fostered further collaborative and community driven research efforts (e.g., a biopsy programme, observational research in estuaries), including research that has supported the health benefits of consuming beluga (lemire et al. 2015; little et al. 2019). nunavut, canada beluga (qilalugaq/qinalugaq) are found in most of nunavut waters. communities in nunavut harvest primarily from four stocks: cumberland sound, eastern high arctic–baffin bay, ehb and whb. with a population estimate of about 54 500, the whb beluga stock is one of the world’s largest (matthews et al. 2017). in the kivalliq region, communities regularly hunt beluga whereas communities in the east kitikmeot region often travel farther distances from the community to hunt beluga. beluga are not observed with regular frequency in west kitikmeot. in the qiqiktaaluk region, beluga are hunted regularly from many communities. the hunting of beluga whales (qinalugaqsiurniq) in the kivalliq region typically commences in early fall (ukiaksaaq), as beluga migrate north along the whb coast (colbeck et al. 2013). hunters generally wait until whales have finished moulting, which occurs in estuaries such as those of the seal, churchill and nelson rivers (st. aubin et al. 1990; smith et al. 2017). inuit rapidly transitioned to motor-powered boats and high-powered rifles as the technology became available but they also retain many of traditional practices and equipment. traditional practices govern the management of most of the stocks in nunavut; however, for the cumberland sound beluga stock, which was decimated by commercial whalers and the hudson bay company between 1868 and 1939, quotas were enacted by the federal government in amendments to the beluga and narwhal protection regulations in 1980 and 1990 (stevenson 1997; kilabuk 1998; stewart 2018). the establishment of the quotas has contributed to a long-conflicted relationship between dfo and the community of pangnirtung (richard & pike 1991). inuit continue to say that their knowledge has not been valued or applied in management decision-making (freeman et al. 1998). dfo and the community representatives have recently established another working group to co-develop a management plan for this stock, which is intended to include the compilation, mobilization and application of inuit knowledge. beluga remain economically, nutritionally and culturally important (freeman 1993; wein et al. 1996; freeman et al. 1998; tyrrell 2007b; hoover et al. 2013). some cultural practices, such as food sharing, which is important for families and social cohesiveness, are still practiced in all nunavut communities. other historical practices and traditional taboos may no longer be observed, such as sinking carcasses post-harvest to avoid attracting polar bears to harvest locations near communities. “hunters do not sink the carcass. they just harvest it, and leave it on the shoreline. this is due in part why we’re seeing more polar bears coming around… so you need to butcher it properly in order for the carcass to sink into the sea to leave it there” (napayok 2018). research activities in nunavut are beginning to be more attentive to the concerns of communities. the kivalliq wildlife board has recently undertaken a community-based research project to sample whales harvested by inuit youth to determine the health, trend and abundance of the population. inuit are readily positioned to notice any changes in the environment. for example, inuit have observed delays in the beluga migration. the cause remains uncertain, but the increased presence of killer whale (aarluk; orcinus orca) in hudson bay waters observed by inuit (higdon and ferguson 2009; higdon et al. 2014) may be a potential factor (westdal et al. 2016). inuvialuit settlement region, canada inuvialuit and canadian western arctic inuit annually hunt beluga whales (qilalugaq) from the eastern beaufort sea beluga population (day 2002; harwood et al. 2002), as did their ancestors, the kupugmiut and kigirktarumiut (mcghee 1974). inuvialuit beluga hunters know the importance of respect for the beluga and continue cultural practices to take only what is needed and to share what is taken (snow et al. 2016). despite the influences of climate and societal changes, hunters remain adaptable and rely on traditional skills and knowledge as well as values of cooperation, harmony and readiness (collings et al. 2018; worden et al. 2020). hunting typically occurs in summer from small aluminum boats using harpoon-first methods to reduce struck-and-lost incidents, following local by-laws developed by hunters and trappers committees (day 2002; harwood & smith 2002; fjmc 2013). because beluga aggregate in large numbers in the mackenzie estuary/delta in summer (norton & harwood 1986; harwood et al. 1996), hunters operate from summer whaling camps occupied by families from inuvik and aklavik or directly from the coastal community of tuktoyaktuk (waugh et al. 2018; worden et al. 2020). beyond the mackenzie delta area, a beluga harvest has taken place or been attempted by the community of paulatuk in most years since 1989 (harwood et al. 2002). sporadic hunts have also occurred in sachs harbour and ulukhaktok from 2010 to the present as the whales appear to be expanding their summer range (collings et al. 2018; loseto, brewster et al. 2018; loseto, hoover et al. 2018). concurrently, there has been a decline in the number of whales landed in mackenzie estuary hunts since the 1970s (fjmc 2013; harwood et al. 2015), likely due to multiple social and environmental factors (waugh et al. 2018; scharffenberg et al. 2020; harwood et al. 2020; worden et al. 2020). a co-management framework has been in place in the inuvialuit settlement region since 1984. the federal government and the fjmc are responsible for fish and marine mammal management and related matters in the region. the federal government and the fjmc, in co-operation with hunters and trappers committees, have developed conservation management strategies that include the creation of canada’s first two arctic marine protected areas: tarium niryutiat and anuniaqvia niqiqyuam marine protected areas (also spelled tagium nayutiat and anguniaqvia niqigyuam in inuvialuit orthography). tarium niryutiat focuses on beluga, beluga habitats and prey (dfo 2010), and anuniaqvia niqiqyuam includes the conservation of beluga and its habitat. nearly 40 years of eastern beaufort sea beluga cooperative research has resulted from these efforts in the inuvialuit settlement region, generating one of the strongest arctic beluga data sets (loseto, hoover et al. 2018; harwood et al. 2020). the success of this programme is the result of a long-term, sustained and well-resourced collaborative effort between co-management boards, community members and the scientific community. beluga research and monitoring has evolved over the past 40 years, responding to community questions, management needs and scientific investigations that have brought together a community of knowledge-holders working collaboratively to best study beluga. beluga harvest monitoring has revealed a declining trend in size-at-age of male beluga in the mackenzie estuary from 1993 to 2007 (harwood et al. 2015); dietary shifts and impacts on dive physiology (choy et al. 2017; choy et al. 2019; choy et al. 2020); trends in contaminants (loseto et al. 2015; noel et al. 2018); microplastics in beluga (moore et al. 2020); and diseases (nielsen et al. 2018; sharma et al. 2018). community members are part of the planning and field crews, sometimes participate in laboratory analyses (typically youth) and often are part of the dissemination of results at meetings and conferences. inclusion of indigenous knowledge has occurred and continues to occur through the co-development of the research and monitoring programmes (armitage et al. 2011). the beluga harvest monitoring programme includes indigenous knowledge about beluga health and behaviour that are formally documented as long-term monitoring indicators (ostertag et al. 2018). there are additional and long-standing collaborations on research and management of eastern beaufort sea beluga, a shared stock, between the inuvialuit settlement region and alaska, building on several iñupiat–inuvialuit cooperative efforts (kanayurak 2016). the inuvialuit–iñupiat beluga whale commission, which was created in 2000 from the alaska–inuvialuit beluga whale committee (adams et al. 1993), provides a way for hunters to interact with their peers from both regions and also to share scientific findings through a technical committee. the commission meets annually to discuss harvest numbers and current research, share unusual observations and other data and knowledge, and provide joint recommendations on the shared eastern beaufort sea beluga stock. alaska, usa beluga (qilalugaq, sisuaq, cetuaq) hunting practices in alaska vary greatly among the more than 40 involved communities (frost & suydam 2010) and at least five beluga stocks. in spring, beluga whales are hunted from the edge of the shorefast ice while in summer and fall they are taken in open water by net and rifle and by driving groups of beluga into shallow water. apart from a prohibition on waste, there are no harvest limits at present (apart from a federally-imposed ban on any hunting of the endangered stock of beluga in cook inlet in southern alaska [noaa fisheries 2021]), though in some local areas beluga are not as common as they once were. in all beluga-hunting communities, harvesting involves practices deemed respectful to the whales, including mental and physical preparation for the hunt, avoiding conflict among hunters, reducing the number of whales lost during the hunt and sharing the beluga within and beyond the community. while hunting practices have changed in some places with outboard motors, faster boats and better rifles, the values of sharing and respect are understood to be vital to the success of the harvest and to the cultural well-being of the communities (huntington et al. 2017). collaborative research about beluga whales has a long history in alaska, a practice that has increased since the founding of the co-management alaska beluga whale committee in 1988 (adams et al. 1993). hunters, scientists and managers together determine research priorities and carry out projects including aerial surveys (e.g., lowry et al. 2008), satellite telemetry (citta et al. 2017), genetic analyses (e.g., o’corry-crowe et al. 1997), health and contaminants research (e.g., woshner et al. 2002; thompson et al. 2014), indigenous knowledge documentation (e.g., huntington et al. 1999; huntington 2000) and assessment of management approaches (e.g., fernandez-gimenez et al. 2008). hunters participating in research projects are increasingly recognized as co-authors and have also been certified as hunter–taggers by the us national oceanic and atmospheric administration to catch and attach satellite transmitters to beluga, formally recognizing their abilities and role as researchers. the alaska beluga whale committee allocates funding for research projects, giving hunters a strong role in making such decisions, and provides a forum for addressing management issues. chukotka, russia beluga whale (chukchi: puwreq; siberian yupik: poogsyaq) hunting in chukotka has a long and sustainable history diversifying the diet of local communities, although its contribution to the traditional economy is modest (mymrin et al. 1999). today, hunting obshchinas (communities) distributed in 14 villages along the bering strait region harvest no more than 20 beluga whales annually (prochukotku.ru 2020a). from time to time, they are joined by a couple of settlements located on the anadyr river, which take beluga entangled in salmon nets. chukotka has an overall quota system for traditional hunting of marine mammals, which is distributed by the regional fisheries commission (prochukotku.ru 2020b). beluga are hunted mainly in spring and late autumn, when the sea is covered by sea ice. hunters (eveneellyet; chukchi terms relevant to beluga hunting are provided here) prefer these seasons because beluga are very careful and almost impossible to approach by boat (yitw’et). therefore, hunters usually shoot beluga from shore (an’k’asormyn) or the edge of shorefast ice (tukvan). hunters first shoot (mil’gerytkurkyt) at the beluga and then either harpoon (tegryrkyt) them or use a wooden or metal hook (ak’yn) to pull them to the surface. sometimes beluga are trapped in a small opening in the ice far from open water (iyogyrgyn), and local communities have a rare opportunity to provide themselves with tasty food. hunters usually begin to butcher the animal (el’vyk) by cutting off the tail, then cut the skin and fat (itgil’gyn) into square strips, and then cut the meat (an’k’atol’) in the same way and remove the internal organs. the hunter who killed the beluga takes the head of the animal (l’evyt) and, after processing, returns it to the sea. the remaining parts of the beluga are distributed among hunters and also provided to neighbours (enaral’ety). in some villages, the belly (nank’ytol’) and tail (peqǝlɣǝn) of the beluga also belong to the hunter. the chukotka branch of pacific research fisheries center began a long-term study of beluga in chukotka in the 1990s. each year, expeditions to the anadyr estuary collected beluga biopsies and conducted visual animal counts and sometimes carried out satellite tagging and underwater sound studies (litovka et al. 2013). over time, scientists invited local hunters to cooperate. indigenous knowledge and hunting experience ensured the success of the expeditions to collect beluga biopsies and even attach satellite tags. together, scientists and native hunters were able to collect data on the current state of the local beluga whale population. case study of knowledge co-production to support the conservation of an at-risk stock: nunavik, canada background and context there are four stocks of beluga in the nunavik marine region, named for their summering grounds (table 3, fig. 2). we use ‘stock’ as the term is used in nunavik, to define management units based on summering areas and supported by matrilineal genetic analysis, though there is likely interbreeding among at least some of the region’s four stocks. beluga tend to travel together with related individuals, particularly females, and to return to previously used areas, suggesting that migration may be learned through the social structure of more closely related individuals (colbeck et al. 2013). the preservation of the beluga stocks from each of the summering aggregations is considered important to maintain the geographic range of beluga (turgeon et al. 2012). table 3 estimated historical abundances, the most recent aerial survey abundance estimates and the updated 2020 cosewic stock status for the four different beluga stocks found in the nunavik marine region. estimates, particularly historical abundances and the recent estimate for ungava bay, are based on different methods. beluga stock estimated historical abundance (year) abundance estimates (year) cosewic stock status ehb > 6600 (1853)a 12 500 (pre-1854)b 3800 (2015) d,e threatened (as of nov. 2020) whb 31 100 (1987) e 54 500 (2015) e not at risk james bay unknown 10 600 (2015) d,e not at risk ungava bay 1900 (late 1800s) b 32 (2011) c endangered areeves & mitchell (1987). bdfo (2005). cdoniol-valcroze & hammill (2012); 95% confidence interval = 0-94. dgosselin et al. (2017). edfo 2018. fig. 2 summering and wintering areas and approximate migratory routes for the four beluga stocks (whb, james bay, ehb and ungava bay beluga) which inhabit the nunavik marine region for all or part of the year. the ehb stock is of particular interest and challenge for managers (dfo 2020). beluga in ehb were subject to heavy commercial harvesting from the mid-1800s until the early 1900s—an estimated minimum of 8294 whales were taken between 1854 and 1863—and the stock has not recovered (reeves & mitchell 1987; dfo 2018). as a result, this stock, which was estimated to be approximately 3800 animals at the time of the last aerial survey in 2015 (gosselin et al. 2017), is believed to be less than half of what it was historically (hammill et al. 2017). after being considered endangered since 2004 (cosewic 2004), ehb beluga were reassessed by cosewic in late 2020 as threatened on the basis of the relative stability of the population, which has remained the same, or slightly increased, since 2001. cosewic assessments consider factors such as declines in total number of mature animals, whether the reasons for the declines are known and still acting on the species, and whether there have been changes in distribution or range. although inuit harvesting is not considered to have played a part in the initial decline, it has been considered to limit stock recovery, after commercial hunting caused declines (dfo 2020). the ehb stock spends at least half the year spatially overlapping, and likely interbreeding, with the whb stock in their shared wintering areas and during migration (turgeon et al. 2012; colbeck et al. 2013). both stocks migrate through hudson strait in spring and fall. however, the whb stock is estimated to number approximately 54 500 animals (about 15 times the size of the ehb stock) and is not of conservation concern (dfo 2018). while it is difficult for most hunters to discriminate between the stocks, expert hunters assert that they can distinguish animals from the different groups of beluga. however, no one has undertaken the work to determine whether there is a simple, reliable method to differentiate among stocks, aside from genetics, and this needs to be further explored. nunavik beluga management since the 1980s, different quota-based management approaches, including both seasonal and geographic limitations, have been applied. in the 1980s, management decisions were taken and implemented by the federally responsible minister. since nilca came into force in 2008, decision-making has shifted to a formal co-management process. through the nilca, the nmrwb was established and is tasked with being the main instrument of wildlife management in the nunavik marine region, including the establishment and modification of the tat for beluga. the decisions of the nmrwb are delivered for approval to the minister of the government department that has responsibility for the species in question, which is dfo in the case of beluga whales, as government has the ultimate responsibility for wildlife management. regulation in the nunavik marine region is further complicated by overlapping rights between nunavik inuit and the cree of eeyou istchee. wildlife management in the south-eastern part of hudson bay is shared with the eeyou marine region wildlife board. prior to nilca, conservation guided decision-making. under nilca, a constitutionally protected document, inuit rights can only be infringed upon under limited, defined circumstances. therefore, the nmrwb is required both to uphold the principles of conservation, including the restoration and revitalization of depleted population of wildlife, and to protect the harvesting rights of nunavik inuit. given the conservation concerns related to the ehb beluga, a quota-based system has remained in place until the present. under nilca wildlife management provisions, the entirety of the beluga tat is presumed to be needed by nunavik inuit, and non-indigenous people are prohibited from harvesting beluga. allocation of the tat among nunavik communities is determined by the regional hunting organization. the community allocation can then be further allocated by the local community hunting organization if they so choose, but in practice it is usually an open hunt until the quota is reached. since 2014, the tat has been set in multi-year (e.g., 3-5 year) blocks to account for variations in environmental conditions, beluga abundance and community needs, providing a greater degree of flexibility. importantly, the tat has been solely for ehb beluga since 2014. communities have uumajuit wardens, who monitor and report the harvest, but have no enforcement power, while dfo fisheries officers from outside of the region are responsible for enforcing variation orders, acts and regulations (gombay 2019). given the challenges of distinguishing between stocks, tracking harvest levels of ehb beluga is based upon assumed proportions of ehb beluga in the total harvest, with differing proportions depending on the season and hunting area. this proportion is determined using genetic information gathered from previous inuit harvests. despite the changes in the management system, and the shift to a co-management framework, challenges remain in a system that strives to balance conservation with minimizing limits on harvesting rights. indeed, the tat for ehb beluga continues to be reached in some years, resulting in the closure of the entire hunt before or during the fall migration, a hunt of great importance for nunavimmiut. hunters then watch tens of thousands of beluga—mostly from stocks that are not the subject of conservation concern—migrate past their communities and are unable to exercise their harvesting rights. re-allocation of hunting effort to ensure hunting is allowed during the seasons when ehb beluga are less likely to be caught could rectify this situation but must be balanced with respecting the harvesting rights of inuit and the traditional hunting activities of communities more likely to catch ehb beluga. this management model, however, continues to contradict the spirit and intent of nilca and minimal infringement of harvesting rights, since harvest of the large and healthy stock of whb beluga has also been limited in the course of efforts to conserve ehb beluga. the nmrwb is left with the challenge of determining how to manage harvesting of two visually cryptic stocks of beluga with highly coincidental geographic distributions, but vastly different conservation status. bringing inuit knowledge of migratory timing and genetics together in the hudson strait pilot project the hudson strait pilot project was implemented in 2017 as a way of using co-produced knowledge to best balance ehb conservation and harvesting rights. the project uses inuit knowledge of migration timing to avoid harvesting the ehb stock as much as possible, while focusing harvesting on the healthy whb stock. genetic sampling of the harvest is then used to assess the level of success in avoiding the ehb stock. neither inuit knowledge nor the genetic sampling would be sufficient by itself, making a knowledge co-production approach necessary. past genetic sampling has determined the proportions of ehb and whb beluga at different times of year. this information serves as the basis to set the tat for ehb beluga in the nunavik marine region. for example, in hudson strait in the spring, only 10% of beluga are estimated to be ehb, meaning that the harvest of one beluga removes 0.1 beluga from the overall ehb tat for the nunavik marine region. however, in the ehb arc, where 100% of beluga are assumed to be ehb, one beluga harvested removes one beluga from the tat. this allows flexibility in the quota system but causes problems if areas and seasons are not determined at a scale that captures a true estimate of stock mixing at a given time. for example, the entirety of fall (1 september 31 january) is considered one season in hudson strait. however, inuit knowledge from experienced hunters indicates that a smaller migration occurs through hudson strait a few weeks before a larger migration. this smaller group is understood to be the ehb beluga migrating in advance of the whb beluga. in previous management systems, quotas were often annual, which created an inherent challenge in the management system where hunters rushed to harvest early in the fall, before the quota was reached and the hunt was closed. within the current management system there are multi-year tats; however, allocations by the regional hunting organization are still made annually, and usually broken down into a spring and fall harvest, and hunters remain concerned that if they wait to harvest they will miss out on their opportunity to harvest what they need. this rush to hunt in the fall means that hunters are more likely to harvest from the earlier groups of whales, thought to be ehb beluga. this may also be part of the reason why the proportion of ehb beluga in the fall harvest (25%) is higher than in spring (10% ehb). while genetic testing can help validate this knowledge, there are few genetic harvest samples from the late fall because harvests have primarily occurred in the early fall (due to the rush described above) and it is not yet possible to achieve the temporal resolution required. this indicates a situation in which nunavik inuit hunting may be limited more than necessary and the harvest of ehb beluga could be better reduced. during the management decision-making process leading to the 2017-19 harvest seasons, hunters shared this inuit knowledge with the nmrwb regarding migration patterns and viewed it as an important area of potential improvement. in response, the nmrwb developed the hudson strait pilot project, encouraging harvesters to harvest later in the fall, in october and november, from the larger migrating group and to sample their harvest to determine the animals’ stock. to counter the pressure to hunt earlier under a tat system, the nmrwb decided that successful avoidance of ehb beluga, verified with genetic samples, would lead to any unused harvest being carried over to the tat in the following year. hudson strait pilot project outcomes the project was successful in 2017 and 2018; however, in 2019, which was the final year of three-year plan, the hunt was closed before the commencement of the pilot project. between 2017 and 2018, 44 beluga were sampled as part of the pilot project. based upon the assumed proportions used for management of 25% ehb, it was expected that 11 of those 44 whales would be ehb beluga. genetic analysis showed that only seven of the 44 beluga harvested were ehb whales (table 4) resulting in a return of four ehb to the tat. under the proportional tat system, the return of four ehb to the tat is significant, allowing from four to 40 extra beluga to be harvested, depending on the area and season, which is why fractions were included. table 4 pilot project sampling results from 2017 and 2018 with the expected ehb beluga take determined by multiplying the number sampled by 25%, the expected percent of ehb in the stock mixture. note that total samples shown are only those taken during the pilot project time frame. the small sample size requires cautious interpretation. 2017 2018 total sampled 31 13 44 expected ehb (removed from tat) 7.75 3.25 11 actual ehb 6 1 7 difference (returned to tat) 1.75 2.25 4 rather than considering scientific information and inuit knowledge information as two separate pieces of evidence for decision-making, this project integrated the two into a single line of evidence, providing a level of information and knowledge more valuable to all parties than would be possible otherwise. the project has also increased overall hunter support for the harvest monitoring programme and harvest samples substantially increased during the pilot project. the success of the project allowed managers to move forward with a better understanding of the biological system, and therefore with better tools to address conservation concerns while minimally limiting harvesting rights. while this question is specific to beluga in the nunavik marine region, aspects of this issue and solution are relevant to managers working under modern land claims and others who must consider other priorities and needs along with sustaining wildlife populations. discussion indigenous stewardship emphasizes cooperation among people through practices such as sharing and the relationship that is understood to exist between people and animals and that is shown, for example, through respect for what one has harvested. co-management and collaborative research strive for cooperation and harmony through listening, communication, building and maintaining relationships, and working together to identify and achieve common goals and create shared understandings. a synthesis of the regional descriptions, including traditional values, stewardship practices, management authority and collaborative research activities (table 2) shows many common themes in values and stewardship, as well as the breadth of collaborative research across the entire region. the nunavik case study highlights the strength of a co-production model for bringing knowledge together to support both harvesting and conservation. this example is relevant not only to other beluga populations but is more broadly applicable, particularly to the stewardship of other large migratory and harvested species, such as green sea turtles (chelonia mydas) and dugongs (dugong dugon), about which the values and discourse between managers and harvesters also differ (nursey-bray et al. 2010). the challenge today is to build on what has been accomplished already, in the context of continuing environmental and social change. co-management and other collaborative efforts have led the way to develop management plans that ensure hunting is sustainable, but often have little influence over climate change, shipping, industrial development, pollution and other threats to the health and abundance of beluga. some beluga stocks are abundant and healthy, whereas others are small and declining. stocks used by different communities within a region, among regions or internationally require an additional level of management cooperation, as can be seen in regional organizations as well as international ones such as the inuvialuit–iñupiat beluga commission, in the beaufort sea, and the joint commission on narwhal and beluga, in baffin bay. collaborative research has greatly increased our understanding of beluga whales and their ecosystems, but rapid environmental changes may alter beluga behaviour and distribution, rendering much of current understanding at risk of being dated and eventually obsolete. greater recognition of the importance of indigenous values, knowledge and stewardship—not least among indigenous communities themselves—has helped spur indigenous-led efforts to conserve beluga and their abundance, but rapid social change may interfere with passing these traditions down to younger generations (pearce et al. 2011). the hard-won gains of cooperation are still vulnerable to being lost or weakened without continued investment of time and effort, the more so as knowledge—both indigenous and scientific—needs to be kept up to date. the application of outside wildlife management measures to indigenous hunting practices in the arctic has often created tensions or conflicts and has sometimes countered conservation efforts (huntington 1992; meltofte 2013), as exemplified by the nunavik case presented here (tyrell 2007a,b, 2008). the recognition of the depth of indigenous knowledge, the growth in collaborative research and the development of a forum through co-management systems have all helped transform interactions among hunters, researchers and managers toward a shared commitment to conserving abundant wildlife and sustaining indigenous ways of life (armitage et al. 2011; huntington et al. 2011; breton-honeyman, furgal et al. 2016; snook et al. 2018). these steps are not panaceas, requiring hard and honest conversations, and each has created controversy and opposition at times (fernandez-gimenez et al. 2006), but such efforts are an important contribution to the well-being of the environment and its inhabitants. as participants in the mystic workshop found, sharing ideas and experiences across regions, especially among indigenous communities, can help reinforce the importance of stewardship and collaboration and inspire further efforts as one region finds new ideas from another. in canada, it is hoped that the creation of the new dfo arctic region, which will include all of inuit nunangat, will increase effectiveness and further these collaborative efforts among regions (dfo 2021). efforts within beluga hunting communities to sustain traditional indigenous stewardship are necessary to pass on the values and knowledge that have been gained over countless generations and adapted to the needs of each time (worden et al. 2020). efforts are also necessary among hunters, researchers and managers so that our understanding keeps pace with change, that we are able together to address the range of challenges facing beluga and hunting communities, and that we pass on not only knowledge but also the values that support such collaboration. retaining the status quo is insufficient. internationally, indigenous peoples are calling for a transformative shift in power and changes in how research is prioritized, conducted and implemented across the arctic with self-determination at the foundation (obed 2016; inuit circumpolar council 2018; inuit tapiriit kanatami 2018). the increased attention to indigenous knowledge and indigenous participation in research and management is a major cultural shift in recent decades but is still in the early stages. more can and should be done (pearce et al. 2009; loseto et al. 2020). for authentic, meaningful collaboration and change, hunters and those impacted by the research and decisions need to be involved in all stages of a project or management system (huntington 2021). at present, however, much hunter inclusion in research remains on a voluntary, contractual or short-term basis, rather than as a means of livelihood as is the case for professional scientists and managers. this split creates a power imbalance and a pervasive perception that formal scientific research has greater value and status. studies involving indigenous knowledge are more common, but still outnumbered by biological research papers, and studies are rarely led by indigenous scholars (breton-honeyman, furgal et al. 2016; alexander et al. 2019). changing these ways will require expanded research funding, the re-allocation of existing funding, or both (inuit tapiriit kanatami 2018). beluga—qilalugaq, qinalugaq, sisuaq, cetuaq, puwreq, poogsyaq—are found throughout the arctic and, for reasons of geography, history and culture, are hunted across half the arctic. much remains to be learned from one another, from understanding how a changing environment affects beluga to sharing successes in research and collaboration and emphasizing the importance and consistency of indigenous values and stewardship across a vast area, as has been started with the inuvialuit–iñupiat -collaboration in the beaufort sea and the inuit–greenlandic cooperation in baffin bay. in addition, more research is needed to compare management systems and experiences to determine how the results of collaborative research are applied locally, regionally and internationally. the future of beluga whales and beluga hunting communities depends on continued cooperation and communication among all who share a vision of abundance in the arctic. in memoriam during the review of this paper, our friend, colleague and co-author, alfred jakobsen, passed away. we honour his life-long passion for his home of greenland, for all inuit and for the arctic, and for the humour and insight with which he shared that passion. (photo courtesy of oceans north.) acknowledgements we gratefully acknowledge kristin laidre, university of washington; fernando ugarte, greenland institute of natural resources; mike hammill and jeremiah young, dfo; robert moshenko, jean-pierre savard and qajaq robinson, nmrwb; kathy frost, alaska beluga whale committee; davonna kasook, inuvialuit game council; lois harwood, fjmc, for their constructive reviews of earlier drafts of this manuscript. we further thank marjo vierros and an anonymous reviewer for their constructive comments on the manuscript. references adams m., frost, k.j. & harwood l. 1993. alaska and inuvialuit beluga whale committee (aibwc)—an initiative in “at home management.” arctic 46, 134–137, doi: 10.14430/arctic1334. alayco s., bergeron m. & michaud m.d. 2007. inuit elders and their traditional knowledge: beluga hunting and sustainable practices. westmount, qc: avataq cultural institute / ottawa: fisheries and oceans canada. alexander s.m., provencher j.f., henri d.a., taylor j.j., lloren j.i., nanayakkara l., johnson j.t. & cooke s.j.. 2019. bridging indigenous and science‑based knowledge in coastal and marine research, monitoring, and management in canada. environmental evidence 8, article no. 36, doi: 10.1186/s13750-019-0181-3. armitage d., berkes f., dale a., kocho-schellenberg e. & patton e. 2011. co-management and the co-production of knowledge: learning to adapt in canada’s arctic. global environmental change 21, 995–1004, doi: 10.1016/j.gloenvcha.2011.04.006. bailleul f., lesage v., power m., doidge d.w. & hammill m.o. 2012a. differences in diving and movement patterns of two groups of beluga whales in a changing arctic environment reveal discrete populations. endangered species research 17, 27–41, doi: 10.3354/esr00420. bailleul, f., lesage v., power m., doidge d.w & hammill m.o. 2012b. migration phenology of beluga whales in a changing arctic. climate research 53, 169–178 doi: 10.3354/cr01104. blanchet c. & rochette l. 2008. nutrition and food consumption among the inuit of nunavik. nunavik inuit health survey 2004, qanuippitaa? how are we? quebec: institut national de santé publique du québec and nunavik regional board of health and social services. breton-honeyman k., hammill m.o., furgal c.m. & hickie b. 2016. inuit knowledge of beluga whale (delphinapterus leucas ) foraging ecology in nunavik (arctic quebec), canada. canadian journal of zoology 94, 713–726, doi: 10.1139/cjz-2015-0259. breton-honeyman k., furgal c.m. & hammill m.o. 2016. systematic review and critique of the contributions of traditional ecological knowledge of beluga whales in the marine mammal literature. arctic 69, 37–46, doi: 10.14430/arctic4543. brice-bennett c. (ed.) 1977. our footprints are everywhere: inuit land use and occupancy in labrador. nain, nl: labrador inuit association. brice-bennett c. 1978. an overview of the occurrence of cetaceans along the northern labrador coast. report for offshore labrador biological studies program. st. john’s, nl: northern environmental protection branch, northern affairs program. choy e.s., campbell k.l., berenbrink m., roth j. & loseto l.l. 2019. body condition impacts blood and muscle oxygen storage capacity of free-living beluga whales (delphinapterus leucas). journal of experimental biology 222, jeb191916, doi: 10.1242/jeb.191916. choy e.s., giraldo c., rosenberg b. roth j.d., stasko a., majewski a., swanson h., power m., reist j.d. & loseto l.l. 2020. variation in the diet of beluga whales in response to changes in prey availability: insights on changes in the beaufort sea ecosystem. marine ecology progress series 647, 195–210, doi: 10.3354/meps13413. choy e.s., rosenberg b., roth j.d. & loseto l.l. 2017. inter-annual variations in environmental factors affect prey and body condition of eastern beaufort sea beluga whales (delphinapterus leucas). marine ecology progress series 579, 201–212, doi: 10.3354/meps12256. citta j.j., richard p., lowry l.f., o’corry-crowe g., marcoux m., suydam r., quakenbush l.t., hobbs r.c., litovka d.i., frost k.j., gray t., orr j., tinker b., aderman h. & druckenmiller m.l. 2017. satellite telemetry reveals population specific winter ranges of beluga whales in the bering sea. marine mammal science 33, 236–250, doi: 10.1111/mms.12357. colbeck g.j., duchesne p., postma l.d., lesage v., hammill m.o. & turgeon j. 2013. groups of related belugas (delphinapterus leucas) travel together during their seasonal migrations in and around hudson bay. proceedings of the royal society of biological sciences 280, article no. 20122552, doi: 10.1098/rspb.2012.2552. collings p., pearce t. & kann j. 2018. “we don’t know anything about whales”: ecological knowledge and ways of knowing in ulukhaktok, northwest territories, canada. arctic science 241, 223–241, doi: 10.1139/as-2017-0030. cosewic 2004. cosewic assessment and update status report on the beluga whale delphinapterus leucas in canada. ottawa: committee on the status of endangered wildlife in canada. day b. 2002. renewable resources of the beaufort sea for our children: perspectives from an inuvialuit elder. arctic 55, supplement 1, 1–3, doi: 10.14430/arctic730. dfo 2005. recovery potential assessment of cumberland sound, ungava bay, eastern hudson bay and st. lawrence beluga populations (delphinapterus leucas). canadian science advisory secretariat science advisory report 2005/036. ottawa: fisheries and oceans canada. dfo 2010. monitoring indicators for the tarium niryutait marine protected area (tnmpa). canadian science advisory secretariat science advisory report 2010/059. ottawa: fisheries and oceans canada. dfo 2013. identification of additional ecologically and biologically significant areas (ebsas) within the newfoundland and labrador shelves bioregion. canadian science advisory secretariat science advisory report 2013/048. ottawa: fisheries and oceans canada. dfo 2018. harvest advice for eastern and western hudson bay beluga (delphinapterus leucas). canadian science advisory secretariat science advisory report 2018/008. ottawa: fisheries and oceans canada. dfo 2020. 2020 harvest advice for eastern hudson bay beluga (delphinapterus leucas). canadian science advisory secretariat science advisory report 2020/031. ottawa: fisheries and oceans canada. dfo 2021. fisheries and oceans canada and canadian coast guard confirm new regions’ boundaries to improve services to the arctic. accessed on the internet at https://www.canada.ca/en/fisheries-oceans/news/2021/03/fisheries-and-oceans-canada-and-canadian-coast-guard-confirm-new-regions-boundaries-to-improve-services-to-the-arctic.html on 19 october 2021. doidge w., adams w. & burgy c. 2002. traditional ecological knowledge of beluga whales in nunavik: interviews from puvirnituq, umiujaq and kuujjuaraapik. report 12-419 of the nunavik research centre submitted to environment canada’s habitat stewardship program for species at risk. kuujjuaq, qc: makivik corporation. doniol-valcroze t. & hammill m.o. 2012. information on abundance and harvest of ungava bay beluga. canadian science advisory secretariat research document 2011/126. ottawa: fisheries and oceans canada. fernandez-gimenez m.e., huntington h.p. & frost k.j. 2006. integration or co-optation? traditional knowledge and science in the alaska beluga whale committee. environmental conservation 33, 306–315, doi: 10.1017/s0376892906003420. fernandez-gimenez, m.e., hays j.u. jr., huntington h.p., andrew r. & goodwin w. 2008. ambivalence toward formalizing customary resource management norms among alaska native beluga whale hunters and tohono o’odham livestock owners. human organization 67, 137–150, doi: 10.17730/humo.67.2.008083027273n05q. fjmc 2013. beaufort sea beluga management plan. 4th amended printing. inuvik, nt: fisheries joint management committee. freeman m.m.r. 1993. the international whaling commission, small type whaling, and coming to terms with subsistence. human organization 52, 243–251. freeman m.m.r., bogoslovskaya l., caulfield r.a., egede i., krupnik i.i. & stevenson m.g. (eds.) 1998. inuit, whaling, and sustainability. walnut creek, ca: altamira press. frost k.j. & suydam r.s. 2010. subsistence harvest of beluga or white whales (delphinapterus leucas) in northern and western alaska, 1987–2006. journal of cetacean research management 11, 293–299. gombay n. 2019. wildlife management in nunavik: structures, operations, and perceptions following the james bay and northern quebec agreement. arctic 72, 181–196, doi: 10.14430/arctic68287. gosselin j.-f., hammill m.o. & mosnier a. 2017. indices of abundance for beluga (delphinapterus leucas) in james bay and eastern hudson bay in summer 2015. canadian science advisory secretariat research document 2017/067. ottawa: fisheries and oceans canada. hammill m.o., lesage v., gosselin j.-f., bourdages h., de march b.g.e. & kingsley m.c.s. 2004. evidence for a decline in northern quebec (nunavik) belugas. arctic 57, 183–195. hammill m.o., stenson g.b. & doniol-valcroze t. 2017. a management framework for nunavik beluga. canadian science advisory secretariat research document 2017/060. ottawa: fisheries and oceans canada. harwood l.a., innes s., norton p. & kingsley m.c.s. 1996. distribution and abundance of beluga whales in the mackenzie estuary, southeast beaufort sea, and west amundsen gulf during late july 1992. canadian journal of fisheries and aquatic sciences 53, 2262–2273, doi: 10.1139/f96-180. harwood l.a., kingsley m.c.s. & pokiak f. 2015. monitoring beluga harvests in the mackenzie delta and near paulatuk, nt, canada: harvest efficiency and trend, size and sex of landed whales, and reproduction, 1970–2009. canadian manuscript report of fisheries and aquatic sciences 3059. winnipeg: fisheries and oceans canada. harwood l.a., norton p., day b. & hall p.a. 2002. the harvest of beluga whales in canada’s western arctic: hunter-based monitoring of the size and composition of the catch. arctic 55, 10–20, doi: 10.14430/arctic687. harwood l.a. & smith t.g. 2002. whales of the inuvialuit settlement region in canada’s western arctic: an overview and outlook. arctic 55, 77–93, doi: 10.14430/arctic736. harwood l.a., zhu x., angasuk l., emaghok l., ferguson s., gruben c., gruben p., hall p., illasiak j., illasiak j., lennie j., lea e.v., loseto l.l., norton p., pokiak c., pokiak f., rogers h., snow k. & storr w. 2020. research, monitoring and hunter knowledge in support of the 2017 assessment of the eastern beaufort sea beluga stock. canadian science advisory secretariat research document 2020/075. ottawa: fisheries and oceans canada. heide‐jørgensen m.p., hansen r.g., fossette s., nielsen n.h., borchers d.l., stern h. & witting l. 2017. rebuilding beluga stocks in west greenland. animal conservation 20, 282–293, doi: 10.1111/acv.12315. heide-jørgensen m.p., laidre k., borchers d., marques t., stern h. & simon m. 2010. the effect of sea-ice loss on beluga whales (delphinapterus leucas) in west greenland. polar research 29, 198–208, doi: 10.3402/polar.v29i2.6061. higdon j.w. & ferguson s.h. 2009. loss of arctic sea ice causing punctuated change in sightings of killer whales (orcinus orca) over the past century. ecological applications 19, 1365–1375, doi: 10.1890/07-1941.1. higdon j.w., westdal k.h. & ferguson s.h. 2014. distribution and abundance of killer whales (orcinus orca) in nunavut, canada—an inuit knowledge survey. journal of the marine biological association of the uk 94, 1293–1304, doi: 10.1017/s0025315413000921. hobbs r.c., reeves r.r., prewitt j.s., desportes g., breton-honeyman k., christensen t., citta j.j., ferguson s.h., frost k.j., garde e., gavrilo m., ghazal m., glazov d.m., gosselin j.-f., hammill m., hansen r.g., harwood l., heide-jørgensen m.p., inglangasuk g., kovacs k.m., krasnova v.v., kuznetsova d.m., lee d.s., lesage v., litovka d.i., lorenzen e.d., lowry l.f., lydersen c., matthews c.j.d., meschersky i.g., mosnier a., o’corry-crowe g., postma l., quakenbush l.t., shpak o.v., skovrind m., suydam r.s. & watt c.a. 2019. global review of the conservation status of monodontid stocks. marine fisheries review 81, 1–53, doi: 10.7755/mfr.81.3-4.1. hoover c., bailey m., higdon j., ferguson s.h. & sumaila r. 2013. estimating the economic value of narwhal and beluga hunts in hudson bay, nunavut. arctic 66, 1–16, doi: 10.14430/arctic4261. huntington h.p. 1992. wildlife management and subsistence hunting in alaska. london: belhaven press. huntington h.p. 2000. traditional knowledge of the ecology of belugas, delphinapterus leucas, in cook inlet, alaska. marine fisheries review 62, 134–140. huntington h.p. 2021. engaging with indigenous environmental knowledge in the north american arctic: moving from documentation to decisions in environmental governance. in t.f. thornton & s.a. bhagwat (eds.): the routledge handbook of indigenous environmental knowledge. pp. 146–152. london: routledge. huntington h.p. & the communities of buckland, elim, koyuk, point lay and shaktoolik. 1999. traditional knowledge of the ecology of beluga whales (delphinapterus leucas) in the eastern chukchi and northern bering seas, alaska. arctic 52, 49–61. huntington h.p., gearheard s., mahoney a.r. & salomon a.k. 2011. integrating traditional and scientific knowledge through collaborative natural science field research: identifying elements for success. arctic 64, 437–445, doi: 10.14430/arctic4143. huntington h.p., quakenbush l.t. & nelson m. 2017. evaluating the effects of climate change on indigenous marine mammal hunting in northern and western alaska using traditional knowledge. frontiers in marine science 4, article no. 319, doi: 10.3389/fmars.2017.00319. inuit circumpolar council 2018. inuit circumpolar council wildlife management summit report. ottawa: inuit circumpolar council. inuit tapiriit kanatami 2018. national inuit strategy on research. ottawa: inuit tapiriit kanatami. kanayurak n.l. 2016. a case study of polar bear co-management in alaska. master’s thesis, university of washington, seattle, wa. kenny t. & chan h.m. 2017. estimating wildlife harvest based on reported consumption by inuit in the canadian arctic. arctic 70, 1–12, doi: 10.14430/arctic4625. kilabuk p. 1998. a study of inuit knowledge of the southeast baffin beluga. iqaluit, nu: nunavut wildlife management board. lee d., doidge w., burgy c. & adams w. 2002. traditional ecological knowledge in relation to the management of beluga whales in nunavik. phase i. interviews at kangirsuk, salluit and inukjuak. kuujjuaq, qc: makivik corporation. lemire m., kwan m., laouan-sidi a.e, muckle g., pirkle c., ayotte p. & dewailly e. 2015. local country food sources of methylmercury, selenium and omega-3 fatty acids in nunavik, northern quebec. science of the total environment 509/510, 248–259, doi: 10.1016/j.scitotenv.2014.07.102. lewis a.e., hammill m.o., power m., doidge d.w. & lesage v. 2009. movement and aggregation of eastern hudson bay beluga whales (delphinapterus leucas): a comparison of patterns found through satellite telemetry and nunavik traditional ecological knowledge. arctic 62, 13–24, doi: 10.14430/arctic109. litovka d.i., andronov p.y. & batanov r.l. 2013. seasonal distribution of beluga whales delphinapterus leucas depending on prey concentrations in coastal waters of north-western bering sea. the researches of the aquatic biological resources of kamchatka and of the northwest part of the pacific ocean 28. petropavlovsk-kamchatsky, russia: kamchatka research institute of fisheries and oceanography. (in russian with english title and abstract.) little m., achouba a., dumas p., ouellet n., ayotte p. & lemire m. 2019. determinants of selenoneine concentration in red blood cells of inuit from nunavik (northern québec, canada). environment international 127, 243–252, doi: 10.1016/j.envint.2018.11.077. loseto l.l., breton-honeyman k., etiendem d.n., johnson n., pearce t., allen j., amos a., arqviq j. baak j., belanger e., bourdages m., brammer j., fawcett d., gerin-lajoie j., gilbert g., hansen-craik k., loring e., perrin a. & slavitch m. 2020. indigenous participation in peer review publications and the editorial process: reflections from a workshop. arctic science 6, 352–360, doi: 10.1139/as-2020-0023. loseto l.l. brewster j.d., ostertag s., snow k., macphee s.a., mcnicholl d.g., choy e.s., giraldo c. & hornby c. 2018. diet and feeding observations from an unusual beluga harvest in ulukhaktok northwest territories, canada. arctic science 4, 421–431, doi: 10.1139/as-2017-0046. loseto l.l., hoover c.h., ostertag s.k., whalen d., pearce t., paulic j., iacozza j. & macphee s. 2018. beluga whales (delphinapterus leucas), environmental change and marine protected areas in the western canadian arctic. estuarine and coastal shelf systems 212, 128–137, doi: 10.1016/j.ecss.2018.05.026. loseto l.l., stern g.a. & macdonald r.m. 2015. distant drivers or local signals: where do mercury trends in western arctic belugas originate? science of the total environment 509/510, 226–236, doi: 10.1016/j.scitotenv.2014.10.110. lowry l.f., frost k.j., zerbini a., demaster d. & reeves r.r. 2008. trend in aerial counts of beluga or white whales (delphinapterus leucas) in bristol bay, alaska, 1993–2005. journal of cetacean research management 10, 201–207. lucier c.v. & vanstone j.w. 1995. traditional beluga drives of the iñupiat of kotzebue sound, alaska. fieldiana. anthropology new series 25. chicago: field museum of natural history. matthews c.j.d., watt c.a., asselin n.c., dunn j.b., young b.g., montsion l.m., westdal k.h., hall p.a., orr j.r., ferguson s.h. & marcoux m. 2017. estimated abundance of the western hudson bay beluga stock from the 2015 visual and photographic aerial survey. canadian science advisory secretariat research document 2017/061. ottawa: fisheries and oceans canada. mccarney p., cote d., laing r., wells n., roul s., novaczek e., colbourne e., maillet g., anderson m.r., denniston m., wareham v., neves b., murphy a., gullage l., allard k., gjerdrum c., fifield d., wilhelm s., janes j., pretty c., gullage m., lawson j., stenson g., paquet j., hedd a. & robertson g. 2021. biophysical and ecological overview of a study area within the labrador inuit settlement area zone. canadian science advisory secretariat research document 2021/003. ottawa: fisheries and oceans canada. mcghee r. 1974. beluga hunters: an archaeological reconstruction of the history and culture of the mackenzie delta kittygaryumuit. newfoundland social and economic studies 13. st. john’s, nl: memorial university of newfoundland. meehan r.h., belikov s., desportes g., ferguson s.h., kovacs k.m., laidre k.l., stenson g.b., thomas p.o., ugarte f. & vongraven d. 2017. marine mammals. in: state of the arctic marine biodiversity report. pp. 149–173. akureyri: conservation of arctic flora and fauna international secretariat. meltofte h. (ed.) 2013. arctic biodiversity assessment. status and trends in arctic biodiversity. akureyri, iceland: conservation of arctic flora and fauna. moore r.c., loseto l., noel m., etemadifar a., brewster j.d., macphee s., bendell l. & ross p.s. 2020. microplastics in beluga whales (delphinapterus leucas) from the eastern beaufort sea. marine pollution bulletin 150, article no. 110723, doi: 10.1016/j.marpolbul.2019.110723. mosnier a., hammill m., turgeon s. & postma l. 2017. updated analysis of genetic mixing among beluga stocks in the nunavik marine region and belcher islands area: information for population models and harvest allocation. canadian science advisory secretariat research document 2017/016. ottawa: fisheries and oceans canada. the communities of novoe chaplino, sireniki, uelen, and yanrakinnotmymrin n.i., & huntington h.p. 1999. traditional knowledge of the ecology of beluga whales (delphinapterus leucas) in the northern bering sea, chukotka, russia. arctic, 62–70, doi: 10.14430/arctic910. nammco 2018. report of the nammco global review of monodontids, 13–16 march 2017, hillerød, denmark. tromsø, norway: north atlantic marine mammal commission. nammco 2021. beluga. north atlantic marine mammal commission. accessed on the internet at https://nammco.no/topics/beluga/ on 31 august 2021. napayok j. 2018. nwmb 2018 hearing on whb polar bears total allowable harvest harvest modification. transcript accessed on the internet at https://www.nwmb.com/en/public-hearings-a-meetings/public-hearings-1/2018/western-hudson-bay-polar-bear-modification-of-the-total-allowable-harvest-in-person-public-hearing/nwmb-relevant-documents-35/7494-2017-whb-polar-bear-hearing-transcript/file on 19 october 2021. nielsen o., burek-huntington k.a., loseto l.l., morell m. & romero c.h. 2018. alphaherpesvirus: isolation, identification, partial characterisation, associated pathologic findings and epidemiology in beluga whales (delphinapterus leucas) in alaska and arctic canada. arctic science 4, 338–357, doi: 10.1139/as-2017-0043. noaa fisheries 2021. beluga whale. national oceanic and atmospheric administration fisheries. accessed on the internet at https://www.fisheries.noaa.gov/species/beluga-whale#overview on 19 october 2021. noel m., stern g.a. & loseto l.l. 2018. legacy contaminants in the eastern beaufort sea beluga whales (delphinapterus leucas): are temporal trends reflecting regulations? arctic science 4, 358–372, doi: 10.1139/as-2017-0049. norton p. & harwood l.a. 1986. distribution, abundance and behavior of white whale in mackenzie estuary. report 036. ottawa: environmental studies revolving funds. nursey-bray m., marsh h. & ross h. 2010. exploring discourses in environmental decision making: an indigenous hunting case study. society & natural resources 23, 366–382, doi: 10.1080/08941920903468621. obed n. 2016. free, prior & informed consent and the future of inuit self-determination. northern public affairs 4, 38–41. o’corry-crowe g.m., suydam r.s., rosenberg a., frost k.j. & dizon a.e. 1997. phylogeography, population structure, and dispersal patterns of the beluga whale, delphinapterus leucas, in the western nearctic revealed by mitochondrial dna. molecular ecology 6, 955–970, doi: 10.1046/j.1365-294x.1997.00267.x. ostertag s., loseto l.l., snow k., lam j., hynes k. & gillman v. 2018. “that’s how we know they’re healthy”. the inclusions of indigenous knowledge in beluga health monitoring in the inuvialuit settlement region. arctic science 4, 292–320, doi 10.1139/as-2017-0050. palsbøll p.j., heide-jørgensen m.p. & bérubé m. 2002. analysis of mitochondrial control region nucleotide sequences from baffin bay belugas (delphinapterus leucas): detecting pods or sub-populations? nammco scientific publications 4, 39–50, doi: 10.7557/3.2836. pearce t.d., ford j.d., laidler g.j., smit b., duerden r., allarut m., andrachuk m., baryluk s., dialla a., elee p., goose a., ikummaq t., joamie e., kataoyak f., loring e., meakin s., nickels s., shappa k., shirley j. & wandel j. 2009. community collaboration and climate change research in the canadian arctic. polar research 28, 10–27, doi: 10.1111/j.1751–8369.2008.00094.x. pearce t., wright h., notaina r., kudlak a., smit b., ford j.d. & furgal c. 2011. transmission of environmental knowledge and land skills among inuit men in ulukhaktok, northwest territories, canada. human ecology 39, 271–288, doi: 10.1007/s10745-011-9403-1. prochukotku.ru. 2020a. bolee tysjači moržej smogut dobyt’ morzveroboi čukotki v etom godu. (more than a thousand walrus can be caught this year.) accessed on the internet at https://prochukotku.ru/20200120/10075.html on 31 august 2021. prochukotku.ru. 2020b. kvoty na dobyču kitov raspredelili na čukotke. (whale quotas distributed in chukotka.) accessed on the internet at https://prochukotku.ru/news/actual/kvoty_na_dobychu_kitov_raspredelili_na_chukotke_10655/ on 31 august 2021. reeves r.r. & mitchell e. 1987. history of white whale (delphinapterus leucas) exploitation in eastern hudson bay and james bay. canadian special publications on fisheries and aquatic sciences 95. ottawa: department of fisheries and oceans. richard p.r., heide-jørgensen m.p., orr j.r., dietz r. & smith t.g. 2001. summer and autumn movements and habitat use by belugas in the canadian high arctic and adjacent areas. arctic 54, 207–222, doi: 10.14430/arctic782. richard p.r. & pike d.g. 1993. small whale co-management in the eastern canadian arctic: a case history and analysis. arctic 46, 138–143, doi: 10.14430/arctic1335. scharffenberg k., whalen d., macphee s., marcoux m., iacozza j., davoren g. & loseto l. 2020. oceanographic, ecological, and socio-economic impacts of an unusual summer storm in the mackenzie estuary. arctic science 6, 62–76, doi: 10.1139/as-2018-0029. sejersen f. 2001. hunting and management of beluga whales (delphinapterus leucas) in greenland: changing strategies to cope with new national and local interests. arctic 54, 431–443, doi: 10.14430/arctic800. sharma r., loseto l.l., ostertag s.k., tomaselli m., bredtmann m.c., crill c., rodriquez-pinacho c., schultz d., jung d., shrethsa k., jindal p. & jenkins e.j. 2018. qualitative risk assessment of impact of toxoplasma gondii on health of beluga whales, delphinapterus leucas from the eastern beaufort sea, northwest territories. arctic science 4, 321–337, doi: 10.1139/as-2017-0037. smith a.j., higdon j.w., richard p., orr j., bernhardt w. & ferguson s.h. 2017. beluga whale summer habitat associations in the nelson river estuary, western hudson bay, canada. plos one 12, e0181045, doi: 10.1371/journal.pone.0181045. snook j., cunsolo a. & dale a. 2018. co-management led research and sharing space on the pathway to inuit self-determination in research. northern public affairs 6, 52–56. snow k., o’hara s., esogak d.j., ostertag s.k. & loseto l.l. 2016. our beluga, fish and environment are changing: traditional knowledge study on food resources on kendall island in the inuvialuit settlement region. paper presented at the arctic observing summit, 12–18 march, fairbanks, ak. st. aubin d.j., smith t.g. & geraci j.r. 1990. seasonal epidermal moult in beluga whales, delphinapterus leucas. canadian journal of zoology 58, 359–367, doi: 10.1139/z90-051. stevenson m. 1997. inuit, whalers and cultural persistence: structure in cumberland sound and central inuit social organization. oxford: oxford university press. stewart d.b. 2018. commercial and subsistence catches of beluga whales (delphinapterus leucas) from cumberland sound, nunavut, 1840–2016. canadian technical report of fisheries and aquatic sciences 3250. ottawa: fisheries and oceans canada. taylor j.g. 1977. traditional land use and occupancy by the labrador inuit. in c. brice-bennett (ed.) 1977. our footprints are everywhere: inuit land use and occupancy in labrador. pp. 49–58. nain, nl: labrador inuit association. taylor j.g. & taylor h.r. 1977. inuit land use and occupancy in the okak region, 1776–1830. in c. brice-bennett (ed.) 1977. our footprints are everywhere: inuit land use and occupancy in labrador. pp. 59–82. nain, nl: labrador inuit association. thompson l.a., spoon t.r., goertz c.e.c., hobbs r.c. & romano t.a. 2014. blow collection as a non-invasive method for measuring cortisol in the beluga (delphinapterus leucas). plos one 9, e114062, doi: 10.1371/journal.pone.0114062. thomsen m.l. 1993. local knowledge of the distribution, biology, and hunting of beluga and narwhal: a survey among inuit hunters in west and north greenland. nuuk, greenland: greenland hunters’ and fishermen’s association, greenland home rule authorities, and inuit circumpolar conference. turgeon j., duchesne p., colbeck g.j., postma l.d. & hammill m.o. 2012. spatiotemporal segregation among summer stocks of beluga (delphinapterus leucas) despite nuclear gene flow: implication for the endangered belugas in eastern hudson bay (canada). conservation genetics 13, 419–433, doi: 10.1007/s10592-011-0294-x. tyrrell m. 2007a. quaqtarmiut and beluga whales: knowledge, practice and the impact of beluga whale management. cambridge, uk: scott polar research institute. tyrrell m. 2007b. sentient beings and wildlife resources: inuit, beluga whales and management regimes in the canadian arctic. human ecology 35, 575–586, doi: 10.1007/s10745-006-9105-2m. tyrrell m. 2008. nunavik inuit perspectives on beluga whale management in the canadian arctic. human organization 67, 322–334, doi: 10.17730/humo.67.3.47826252k0623352. waugh d., pearce t., ostertag s., collings p. & loseto l. 2018. inuvialuit traditional ecological knowledge of beluga whale (delphinapterus leucas) under changing climatic conditions in tuktoyaktuk, nt. arctic science 4, 242–258, doi: 10.1139/as-2017-0034. wein e., freeman m. & makus j. 1996. use of and preference for traditional foods among the belcher island inuit. arctic 49, 256–264, doi: 10.14430/arctic1201. westdal k.h., davies j., macpherson a., orr j. & ferguson s.h. 2016. behavioural changes in belugas (delphinapterus leucas) during a killer whale (orcinus orca) attack in southwest hudson bay. canadian field-naturalist 130, 315–319, doi: 10.22621/cfn.v130i4.1925. worden e., pearce t., gruben m., ross d., kowana c. & loseto l. 2020. social–ecological changes and implications for understanding the declining beluga whale (delphinapterus leucas) harvest in aklavik, nt. arctic science 6, 229–246, doi: 10.1139/as-2019-0027. woshner v.m., o’hara t.m., eurell j.a., wallig m.a., bratton g.r., suydam r.s. & beasley v.r. 2002. distribution of inorganic mercury in liver and kidney of beluga and bowhead whales through autometallographic development of light microscopic tissue sections. toxicologic pathology 30, 209–215, doi: 10.1080/019262302753559542. maintenance of the arctic ocean large-scale baroclinic structure by the m2 tide igor v polyakov polyakov, igor v. 1995 00 00: maintenance of the arctic ocean large-scale baroclinic structure by the m2, tide a three-dimensional structure of the m2 tidal currents has been reproduced by mathematical modelling. the possibility of energy transfer from the tidal barotropic motion to large-scale baroclinic circulation of the arctic ocean has been estimated. it has been shown that the bottom relief plays an important role in the formation of the large-scale pattern of the baroclinic fields. the hypothesis has been proposed that the m2 tide may support the near-slope convection of the east-siberian and laptev seas. polar research 13(2)), 21%232 igor v . polyakou. arctic rk antarctic research institute, 38 bering st., st. petenburg 199397, russia. introduction the objective of this study is to estimate the influence of the arctic ocean m2 tide on the formation of the ocean’s density and velocity fields. the study of the arctic ocean tides has a long history. in 1924, defant showed that the arctic ocean semi-diurnal tides are caused by the tidal wave spreading from the atlantic ocean, and that diurnal tides are formed in the arctic. later, several studies have appeared where the tidal dynamics of the arctic ocean both as a separate basin (gjevik & straume 1989; kowalik 1981; kowalik & proshutinsky 1993; kowalik & unter steiner 1978; proshutinsky 1993) and as a part of the world ocean (hendershott 1977; schwiderski 1980 and others) has been investigated. for vari ous reasons the authors of the mentioned studies took into account the two-dimensional structure of the tides in the barotropic ocean only. one of the first attempts to investigate the tides in a baroclinic ocean was a paper by kagan (1968). using some assumptions, kagan analytically obtained relations for the calculation of the sea water level, density and three components of the velocity vector in the tidal flow. the influence of the sea water stratification on the tidal dynamics by a dimensionless parameter has been estimated. it was shown that the tidal surface elevation and currents in a baroclinic ocean differ insignificantly from that in the stratified ocean. several models of tidal dynamics in a stratified two-dimensional channel (x-z axes) have been developed (blumberg 1976; hamilton 1976; johns 1975; johns 1978). on the one hand, such models have been an excellent proving ground for the development of three-dimensional (3d) baroclinic models. on the other hand, these models have provided quite realistic results for tidal dynamics in narrow channels. in 1976, caponi simulated wind-driven and tidal circulation and salt redistribution in the chesapeake bay using a 3d baroclinic model. he had significant limitations in computer resources, and poor resolution and low order accuracy schemes resulted in very weak tidal variations in the salinity field. the application of a 3d baroclinic model by leendertse & liu (1977) to the san-francisco bay and the alaskan shelf has also been limited by inadequate computer resources. however the authors have later simulated the circulation and baroclinic fields transformation under the joint effect of the wind, tide and fluxes through the open boundaries in the bristol bay (liu & leen dertse 1979) and on the alaskan shelf (liu & leendertse 1987). leendertse and liu estimated the influence of stratification on the tidal dynamics. oey et al. (1985) carried out numerical experi ments in the reconstruction of the circulation and baroclinic processes in the hudson estuary from july to september 1980. they used a 3d time dependent baroclinic model (blumberg & mellor 1983) with free surface. the forces were the tidal wave spreading in the basin from the atlantic ocean, the wind stresses, river inflow, and the 220 igor v . polyakov salinity gradients. because of the high resolution, the model produced eddies. as blumberg and mellor had supposed, the interaction of the den sity and velocity with the bottom relief caused small eddies (3 km x 3 km x 10 m) which moved and were transformed in time. according to blumberg and mellor’s published conclusions, along with the baroclinic instability, this mech anism was considered as the most important pro cess in the estuary. numerical modelling was the method employed in this study. our experiments had two stages. the first was a simulation of the level oscillations and 3d currents produced by the m2 tidal wave penetrating into the barotropic arctic ocean from the atlantic ocean. the comparison of the cal culated and observed sea level data was carried out to validate the model results. unfortunately, we have only been able to use sea level obser vation data. further, we have simulated the m2 tidal dynamics in the stratified arctic ocean. however the objective of the experiment was not only to reproduce the tide in the baroclinic ocean but also to estimate the possible changes in the arctic ocean baroclinic fields caused by per iodical forcing. for this purpose the system with initial horizontally homogeneous salinity was adopted and there were no salt sinks and sources throughout all the basin boundaries during the experiment. due to small temperature-induced density variations in the arctic ocean (aagaard & carmack 1989), we have neglected the tem perature variability. model description the non-linear primitive momentum equations with the boussinesq approximation, the heat and salt balance equations, the hydrostatic and con tinuity equations, and the equation of state are the following a f i / & + ( v v ) f i + f k x u = k ’ v h p + f ; (1) where the advective operator l is defined by lq = af uq)/ax + af vq)/ay + jf wq)/dz; (6) q represents any scalar value, diffusive operator f has the following form f = (&,w = [ q u o + vu)a/dz/az + a m h v ! ~ ] ( u , v ) ; (7) a convective mechanism is described by the term & (t,s) (bryan 1969) and means the vertical weight averaging of the temperature and salinity when the density instability occurs. z is the vertical axis directed vertically down to the bottom from the ocean surface. the symbols used here denote: v = (0,w) = ( u , v , w ) is the velocity vector, w is the vertical velocity component; t is potential temperature; s is salinity; k is the unit vector parallel to the z-axis, f = 2 d i n cp, w = 7.29 x rad/sec is the earth rotation rate, cp is lati tude; p is density; pb is a reference density; p is pressure; g is the acceleration of gravity; a m h , a h h , u m , v h , v s are eddy diffusivity coef ficients of momentum, heat and salt exchange in the horizontal and vertical directions, respect ively; uo = 0.1 cm2/s is the molecular viscosity coefficient; vh = (a/ a x , a/ dy); v z is the hori zontal laplacian operator and divh is the hori zontal divergence vector. the equation of state ( 5 ) is written in the eckart’s form (semtner 1974). in the experiment the temperature variations have been neglected. that seems to be not an excessive assumption as the arctic ocean ther mohaline variability is primarily determined by the salinity (aagaard & carmack 1989). there fore we have used only one equation (4) for the salinity. that has enabled us to reduce the calculation time significantly. the vertical velocity w at the top z = 6 and at the bottom z = h is written respectively w = ag/at v v , ~ ; (8) w = uvhh. (9) here s(x,y,t) is the surface level elevation. for easy reading of the figures we assume that the positive direction of the level deviation is opposite to the z-axis. to reduce the time of calculations we use the splitting procedure when the velocity is presented as a sum of ‘baroclinic’ and ‘barotropic’ com ponents (killworth et al., 1987). we shall deter mine the horizontal components of the velocity maintenance of the arctic ocean large-scale baroclinic structure 221 vector as a sum r / = m / h + u . (10) where m = ( m x , m v ) are vertically integrated mass fluxes m = u d t , (11) i 5 and u = ( u ’ , v ’ ) is the baroclinic velocity with zero vertically mean value which is computed by the equation (1). taking into account the kinematic boundary conditions (8) and (9) we shall integrate the equations (1) and (3) from e to h with respect to z. with consideration of (8) we obtain @/dl + diuhm = 0 ; (12) d m / & -+ fk x m = g m h f + a w h h v i ( m / h ) + p o ’ ( p p ) l u d z gp,’ i fig. i . model domain of the arctic ocean. depth con tours are in metres. ab and cde are the lines of ver tical cross-sections. the numbers 1 , 2. 3. 4 denote points where the vertical salinity profiles have been presented. one grid step is equal to 55.6 k m . 5 (13) here 9 is the bottom stress vector, which is determined by a quadratic law on the mass flux m with 0.0026 drag coefficient; the wind stress vector i? in these expeements was equal to zero. finally, the vector u = (u,v) is obtained by the relation (10) (bryan 1969; killworth et al. 1987). according to prandtl, the coefficient um is described by the expression (voltsinger e t al. 1989): u y = 1 2 1 ar//azl. (14) prandtl’s formula follows from the equation of turbulent energy balance if we keep only the terms of energy generation by velocities shear and dissipation. to calculate a turbulent scale 1 in (14) the following expression has been suggested 1 = & l z . $ h z o , (15) where k = 0.4 is the von karman constant; z h = are the parameters of roughness near the bottom and surface (voltsinger et al. 1989). z h and z , allow allocation of two boundary layers. we use zo = (1 j 3 h 2 z h z e ) / ( h / h o + 1) ( h o = 25 m, h z z h ; zg= z + 2 5 6; z h = z e = 2 s c m 222 lgor v . polyakov @ == 1.2 is an empirical constant) to apply this parameterisation to the deep ocean. the z-axis model formulation is restricted so that the near bottom boundary layer cannot be resolved in case of poor vertical resolution in the model. also, the theoretical values of the roughness parameters z h and z p (voltsinger et al. 1989) are too small to play any significant role in experiments when the vertical grid step exceeds several metres. a different approach is used to calculate the heat ah and salt as coefficients of turbulent exchange. the following expression has been obtained (kalatsky 1978): d = idfl/dzi* + o.o67(a~t>/dz, taking into account the possibility of generating an isothermal layer. to calculare the coeffici ent us the term -733.3d(a$)/3r instead of 0.067d(&t>/dz is used (kalatsky 1978). r u ~ and as are taken to equal to 0.1 (kalatsky 1978). at the horizontal walls the boundary conditions are adopv.ed as the perfect insulation and slip for the velocity. for open boundaries we have used the tidal level oscillations (proshutinsky 1993). the zero velocities and undisturbed sea surface have been starting conditions. the initial salinity distribution has been vertically stable and hori zontally homogeneous and during the experiment all the basin boundaries including open ones were closed for the salt exchange. the discrete approximation of the model equations is given in (polyakov et al. 1994). the problem was solved numerically. a model ling area, developed by proshutinsky (1993), includes the arctic ocean, the greenland, norwegian and bartents seas (fig. 1). the grid points have uniformly covered the domain with the step of 55.6 km. nineteen vertical levels were used. the time steps were equal to 150 seconds and approximately 1.2 hour for the twoand three-dimensional blocks of the model. the latter time step has been taken for physical cause to resolve the tidal oscillations (it has been much smaller than a numerical stability criterion de mands). the duration of the calculation was 250 tidal periods. the resulting salinity had oscil lations within a tidal period, but being averaged fig. 2. simulated tidal water level oscillations. solid tines are isophases (degrees), dashed lines are isoamplitudes (cm). maintenance of the arctic ocean large-scale baroclinic smccf~re 223 a fig. 3. vertical cross-sec tions ab of two com ponents u (a.b) and v (c.d) of the barotropic tidal current for opposite phases (a.c and b.d) of the tidal period (cm/s). 224 lgor v . polyakou for the period, it was constant from one tidal period to another for every grid point. results simulation of the m 2 tide in a barotropic arctic ocean the simulated tidal level map is shown in fig. 2. this scheme looks practically the same to that obtained, for instance by proshutinsky (1993), with a two-dimensional model and with the same grid. t o validate the model results we have used the same sea level data of near-shore stations which were employed by proshutinsky (1993). cor relation analysis of amplitudes and phases sets were carried out. the estimations are practically the same as those of proshutinsky (1993). for example, the correlation coefficient between the calculated and observed amplitudes of the m2 tidal level oscillations is equal to 0.98. the maximal velocities of the m 2 tide are obtained at the boundary with the atlantic ocean, in the baffin and barents seas, on the shelves of the laptev and east-siberian seas. in the central part of the arctic ocean, tidal currents are small and do not exceed 1 cm/s. unfor tunately, we have no current data for the com parison. (the validation of the model by observed current data was carried out by polyakov & dmitriev (1993), while we used high spatial reso lution of baydatskaya guba of the kara sea in the experiment). the model has reproduced a 3d structure of the tidal flow. the vertical cross-sections of the simulated tidal current for the opposite phases of the tidal period are presented in fig. 3. the position of the vertical cross-sections is shown in fig. 1. the continental slope produces a relative separation of three areas with different dynamics of the tidal flow (fig. 3). these areas comprise the shelf area which is significantly current-dependent on near-bottom boundary layer characteristics (polyakov & dmitriev 1993); the deep ocean area, where the tidal current is weak and vertically uniform; and the area of the continental slope with strong spatial variability and the most inten sive dynamics of the tidal flow. the slope of the laptev and new siberian seas is marked out. here the calculated surface velocity is about 20 cm/s, decreasing ith depth of 1-2cm/s. it is fig. 4. coefficients of the vertical turbulent exchange (cm/s) at levels 5 (a), 75 (b) and 500 (c) rn. maintenance of the arctic ocean large-scale baroclinic structure 225 226 zgor v . polyakou a b fcg. 5. the same as in fig. 3, but for the baroclinic ocean. maintenance of the arctic ocean large-scale baroclinic structure 227 important that in fig. 3 one can observe a non periodic component; in the case of absolutely periodical motion, the vertical cross-sections for opposite phases of the tidal period might be dis tinguished by sign only. the calculated vertical viscosity coefficient u y for 5 m, 75 m and 500 m levels is shown in fig. 4a, b and c. the values of the coefficient seem to be verisimilar and their spatial distribution is logical when the maximal values occur in areas with the most developed currents. simulation of the m2 tide in a baroclinic arctic ocean stratification has caused small variations in the structure of the tidal sea level. the statistical analysis of the ‘barotropic’ and ‘baroclinic’ fields shows that the coefficient of correlation is about 1 and the mean square roots of the sea level are 39.31 and 39.23cm for each field. maximal differences are concentrated in areas on the con tinental slope. baroclinicity was a cause for some rather small changes in the tidal currents; the density of the mean kinetic energy of currents was 1.2823 and 1.2796kj/m for the ‘barotropic’ and the ‘baro clinic’ problem, respectively. these changes led mainly to a weakening of the tidal currents. velocity of the deep ocean decreased from approximately 0.5 to 0.35 cm/s. on the east siberian sea slope the tidal current became weaker by about several cm/s. the vertical cross section ab for the tidal currents in the case of the baroclinic arctic ocean is shown in fig. 5. baroclinic effects have also caused an inten sification of the non-periodical component. the tidal currents have been one reason for a reconstruction of the initial horizontally homo geneous salinity field (fig. 6a and b). the resulting salinity is stable, i.e. the average over the tidal period solution was invariable in time. it is important that the equations are non linear. indeed, had we integrated the linear equations for a long period, we should have obtained dissipation of the salinity gradients, i.e. the solution would be trivial. the application of the non-linear equations has enabled us to obtain another result when the balance between dynamical forcing and dissipation has been caused by the appearance of a stable structure (schuster 1984). fig. 6. simulated salinity field at level 5 m. 228 lgor v . polyakov 180a 140' llol 90' fig. 7. observed salinity field at level 5m. (gorsh kov 1980). point 3 point 4 fig. 8. salinity profiles at points 1. 2, 3, 4 (fig. 1). the solid lines denote the initial salinity profiles, the dashed ones present simulated profiles. maintenance of the arctic ocean large-scale baroclinic structure 229 in this study we have not estimated the sen sitivity of the system to its parameter variations, for example, to the initial vertical salinity dis tribution. this is a very important problem of the non-linear system sensitivity. additional experi ments are needed. at the same time, we suppose that the revealing of a stable regime of the system is in itself very important because it allows inves tigation of the mechanisms of the arctic ocean baroclinic fields formation. we have compared the simulated and mean climatic salinity of the arctic ocean (gorshkov 1980) (figs. 6 and 7). these fields have many similar features. the ‘river inflow’ on the siberian shelf, the high-gradient area in the shallows of the barents sea, and the ‘tongue’ of the saltwater penetrating from the greenland sea along the lomonosov ridge on to the laptev sea slope are well traced in fig. 6. a surface salinity minimum was generated in the central part of the arctic ocean. it is changed by the salinity maximum at levels deeper than 75m. the reason for such salinity redistribution is quite simple: weak tidal current in the central part of the arctic ocean has caused minimal erosion of the initial salinity profiles (fig. 8). intensive tidal motion at the eurasian slope, near iceland and the lomonosov ridge has produced more smoothed resulting sal inity profiles. this result will not seem to be so unexpected if we keep in mind that the arctic ocean bottom relief plays a very important, if nor crucial, role 100, 200 2000 ’ 4000 . fig. 9. vertical cross-sections ab (a) and cde (b) of the simulated salinity field 230 &or v . polyakou 200 500. 750 in the formation of the semidiurnal tides (pro shutinsky & polyakov 1990). thus in this exper iment the salinity (density) field ‘feels’ the arctic ocean topography and the tidal dynamics is an intermediate point of this process. therefore we conclude that some large-scale peculiarities of the baroclinic fields may be determined by the arctic ocean bottom relief. one more interesting feature of the calculated salinity fields is the different distribution of the characteristics on continental slopes (fig. 9). on the greenland and the chukchi sea slopes the resulting stratification is rather strong and it is weak at the slope of the laptev (figure is not given) and east-siberian seas. the typical observed density distribution on the laptev sea slope (fig. 10) is very similar to the calculated one. the salinity redistribution has been caused by the current of the semidiurnal tide m2, which itself is mainly determined by the topography of the ocean. thus, peculiarities of continental slopes have had an influence on the salinity struc fig. 10. vertical cross-section of the observed density on the laptev sea continental slope. the values are in deviations from a mean value, a relative unit. fig. 11. simulated baro clinic current at level 5 m . 1 arrows are plotted for every other grid point. the arrows are scaled using the maximal velocity value (about 7 cm/s). , maintenance of the arctic ocean large-scale baroclinic structure 231 ture on the different slopes. we suggest that tidal dynamics may be one reason for intensification of near-slope convection of the laptev and east siberian seas. this conclusion is in good agreement with results of direct measurements of the arctic ocean water mass age: it is about 700 years old in the canadian basin and only about 30 years old in the nansen basin (ostlund et al. 1987). apparently, the bottom relief may determine the intensity of the near-slope convection of the arc tic ocean. horizontal salinity gradients have caused stationary baroclinic circulation. the baroclinic flow at 5 m level is shown in fig. 11. weak density gradients have brought about very slow currents. for instance, current velocity does not exceed 0.01 cm/s in the central and near-shore parts of the ocean. relatively large velocities (several cm/s) occur at the continental slopes of green land, the laptev and east-siberian seas. the kinetic energy of this baroclinic current forms about 2% of the tidal expenditure on the bottom friction. thus the maintenance of the stationary baroclinic circulation by the m2 tide is an additional sink of the barotropic tidal energy. the calculated kinetic energy of the density cur rent may be a measure of this sink. conclusions the m2 tidal level oscillations and 3d currents have been calculated for cases of the barotropic and baroclinic arctic ocean. the arctic ocean can be characterised by three regions: shallow water, slope regions, and the deep ocean area. the tidal dynamics of the shallow water area depends on characteristics of the near-bottom boundary layer. the continental slope regions have very intensive tidal currents with significant vertical variability. the tidal circulation of the deep ocean area is weak. the baroclinicity is one reason for a weakening of the tidal currents and an intensification of its non-periodical component. due to tidal dynamics, the reconstruction of the initial horizontally homogeneous salinity dis tribution occurred. the resulting structure of the salinity field became stable in time which seems to be a property of a non-linear system behaviour. the analysis of the calculated and observed mean climatic salinity fields has shown that these fields have similar features. we have connected this result with the importance of the arctic ocean bottom relief in the formation of the m2 tide which was the only forcing in the experiment. these facts have enabled us to conclude that some large-scale peculiarities of the baroclinic fields may be determined by the ocean topography. it has been suggested that the tidal dynamics may be the cause of the intensification of near slope convection of the laptev and east-siberian seas. this conclusion is based on an analysis of calculated vertical distribution of the salinity at different slopes. the weakest stratification pro duced by the m2 tide occurs on the slope of the laptev and east-siberian seas. in the observed salinity profiles of this area the penetration of light surface water into the deep layers also exists. we have simulated baroclinic currents that cor respond t o the calculated density field of the ocean. the kinetic energy of this current may be a measure of an additional sink of the barotropic tidal energy. acknowledgements. i would like to thank two anonymous reviewers for useful comments on the manuscript. references aagaard, k . & carmack e. c. 1989: the role of sea ice and other fresh water in the arctic ocean. j . geophys. res. 94, 14485-14498. blumberg, a . f. 1976: a two-dimensional numerical model for the simulation of partially mixed estuaries. pp. 323-331 in wiley, m. (ed.): esfuarine processes, vol. 2 . academic press. blumberg, a . f. & mellor, j. l. 1983: diagnostic and prog nostic numerical circulation studies of the south atlantic bight. 1. geophys. res. 88 (cs). 4579-4592. bryan, k . 1969: a numerical method for the study of the circulation of the world ocean. j . compur. phys. 4 (3). 347 376. caponi, e. a . 1976: the simulation of estuarine circulation with a fully three-dimensional numerical model. pp. 332 346in wiley, m. (ed.): estuarine processes, vol. 2 . academic press. defant, a . 1924: die gezeiten des atlantiscen ozeans und des arctischen meeres. ann. hydr. marif. mef. jahrg. (8-9). 152-166,179-184. gjevik, k . b. & straume, t. 1989: model simulation of the m2 and k1 tide in the nordic seas and the arctic ocean. t e l h 41a, i?-96. gorshkov, s. g. 1980: aflas of’oceans. arctic ocean. 190 pp. (in russian). hamilton, p. 1976: on the numerical formulation of a time dependent multi-level model of an estuary, with particular reference to boundary conditions. pp. 347-364 in wiley, m. (ed.): esruarine processes. vol. 2 . academic press. hendershott, m. c. 1977: numerical models of ocean tides. pp. 47-65 in: the sea. wiley interscience, new york. 232 igor v . polyakov johns, b. 1975: the form of the velocity profile in a turbulent shear wave boundary layer. j . geophys. res. vol. 80 136). 5109-5112. johns, b. 1978: the modelling of tidal flow in channel using a turbulent energy closure scheme. 1. phys. oceanogr. 8 (5). 10421049, kagan, b. a . 1968: hydrodynamical models of the tidd motions in a sea. leningrad. hydrometeoizdat. 220 pp. (in russian). kalatsky , v.i. 1978: modelling of the vertical thermal structure of the upper ocean layer. leningrad, hydrometeoizdat. 216 pp. (in russian). killworth, p. d., stamforth, b., webb, b. j. & paterson s. m. 1987: a free surface bryan-cox-semtner model. j . phys. oceanogr. 17 (7). kowalik. 2. 1981: a study of the m2 tide in the ice-covered arctic ocean. modeling, identification and control 1981, 2 , 201-223. kowalik, z. & proshutinsky, a. yu. 3993: diurnaltidesin the arctic ocean. j . geophys. res. 98 (cs), 1644s16468. kowalik, z. & untersteiner, n. 1978: a study of the m2 tide in the arctic ocean. deutsche hydr. zeitsch. 31.216229. leendertse, j . j. & liu, s. k. 1977: a three-dimensional turbulent energy model for nonhomogeneous estuaries and coastal sea systems. pp. 387-405 in nihoul, j . j. (ed.): hydro dynamics of estuaries and fiorak. proc. ninth int. liege colloq. ocean hydrodyn., amsterdam. elsevier scientific publ., new york. liu. s. k. & leendertse, j . j . 1979: a three-dimensional model for estuaries and coastal seas. vol. 6. brisfol bay simulations. rand, r-2405-noaa. 121 pp. liu, s. k. & leendertse, j . j . 1987: modeling the alaskan continental shelf waters. oct. 1987, r-3567-noaairc rand corporation. 136 pp. oey, l.-y., mellor, g. l. & hires. r. 1. 1985: a three dimensional simulation of the hudson-raritan estuary. part 1: description of the model and model simulation. j . phys. oceanogr. 15 ( 1 2 ) , 16761692. ostlund, h. g., possnert, g. & swift, j. h. 1987: ventilation rate of the deep arctic ocean from carbon 14 data. j . geophys. res. 92, 3169-3777. polyakov, i. v., dmitriev, n. e . 1993: modelling of the vertical structure of the storm surges and tides of a shallow-water basin. mefeorologiya i gydrologiya 12, 54-62. (in russian) polyakov, 1. v., kulakov, 1. yu., kolesov. s. a., naumov, a. k., dmitriev n. eu. 1994: coupled ice-ocean dynamics model of the kara sea. tech. report n 4-ya-94. aari, st. petersburg, russia. 194 pp. proshutinsky, a. yu. 1993: the arctic ocean level oscillations. st. petersburg. hydrometeoizdat. 216 pp. (in russian) proshutinsky, a. yu & polyakov, 1. v. 1990: the arctic ocean eigen oscillations. proceedings of a n intern. cot$ on the role of the polar regions in global change, june 11-15 1990. univ. alaska, fairbanks. pp. 347-354. schuster, h. g. 1984: deterministic chaos. an introduction. physik-verlag, weinheim. semtner, a. j . jr. 1974: a n oceanic general circulation model with bottom topography. tech. report n 9. department of meteorology university of california. usa. 99 pp. schwiderski, e . w. 1980: ocean tides. part 11: a hydro dynamical interpolation model. marine geodesy 3 , 2 1 s 2 5 5 . voltsinger, n. e., klevanny, k. a . & pelinovsky e. n. 1989: long-wave dynamics of the near-shore zone. leningrad, hydrometeoizdat. 272 pp. (in russian) research note acanthodian scales and worm tubes from the kapp kjeldsen division of the lower devonian wood bay formation, spitsbergen robert r. ilyes ilyes, r. r. 1995: acanthodian scales and worm tubes from the kapp kjeldsen division of the lower devonian wood bay formation, spitsbergen. polar research 14(1), 89-92. results of a thin section study of bonebeds from the kapp kjeldsen division are presented and discussed. the material for this study was collected in the talus on the south-eastern side of bockfjorden, northern spitsbergen. the stratigraphical position of the kapp kjeldsen division within the devonian strata of spitsbergen is shown in table 1 . the thin sections for this study were not made to standard thickness, but are slightly thicker for better resolution of the vertebrate material. each thin section was individually polished. the photos are made with crossed nichols. robert r . llyes, norsk polarinstitutt, p . o . box 5072 majorstua, n-0301 oslo, norway. ‘j*p&ar,~s,“ acanthodian scales fossils of acanthodians are quite common in the devonian strata of spitsbergen, and occur from the red bay group to the mimerdalen formation (blieck et al. 1987). 0rvig (1967) described the the presence of at least three new genera indi cate that the acanthodian fauna of the kapp kjeldsen division is more diverse than previously considered. invertebrates and plants first acanthodians’ from -the kapp kjeldsen division, xylacanthus grandis and “onchus” ouerathensis based on macrofossils of jaw elements and fin spines. scales from this unit were first reported by ilyes (1990). the scales are all of the “acanthodes” hist ologic-type of moy-thomas & miles (1971). such scales have a thick base of acellular bone with non-vascular canals, and a crown of true dentine. the scale shown in fig. 1a is assigned to the genus cheiracanthus agassiz, 1835, on the basis of external morphology and internal structure of the crown. the scale in fig. 1b has a morphology suggesting that it is a scale from the genus ptych odichtyon gross, 1973. the overall morphology of the scale in fig. 2c suggests that it can be assigned either to the genus cheiracanthus or ptychodichtyon. the scale in fig. 1d has ageneral morphology indicating that it belongs to the genus acanthodes agassiz, 1833. scales from the younger grey hoek formation with a mor phology very similar t o this form have previously been described as acanthodes? sp. (valiukevicius 1979, 1985). worm tubes of the genus spirorbis daudin, 1800, have been found in thin sections together with the acanthodian scales (fig. 2a and b). fossil worm tubes are very rare in the devonian strata of spitsbergen, and have previously only been described from the red bay group (friend 1961). as they are useful in discussions regarding paleo environment, their presence in the kapp kjeldsen division is significant. none of the three specimens of spirorbis found were attached t o substratum; this indicates that they have been transported post mortem. the specimens appear, however, not to be damaged, suggesting that they must have lived near the area of deposition (ilyes 1990). ostracods and charophytes are well repre sented in the bonebeds (fig. 2c-i). valves from both large leperditiid and small, smooth non leperditiid ostracods are present. however, the large and thick valves of the leperditiid ostracods dominate totally in a number of individuals. the leperditiid ostracods are represented only by dis 90 robert r . ilyes articulated valves, while some of the valves of the non-leperditiid ostracods are articulated. articu lated valves indicate short or no post rnortem transport. represented by female reproductive organs, the oogonia. their overall morphology suggests that they belong to the genus trochiliscus, and some of the plant macrofossils found in the studied in the thin sections the charophytes are only material from the kapp kjeldsen division fig j vcrtical thin sections through acanthodian scales. ( a ) genus cheiracanthus, 83 x . (b) genus ptychodichfyon, 85 x . (c) genus prvchodichyon or cheiracanthus. 85 x . (d) genus acanrhodes?. 83 x . fix 2 t h i n sections of invertebrates and plants. ( a ) spirorbis. 40 x . ( b ) spirorbls, 45 x . (c) “bonebed”, 25 x . (d) valve of a ieperditiid ostracod. 40 x . ( e ) unidentified smooth. small ostracod with both valves in situ. 63 x . (f) charophyte oogonia (trochrlrscw 5p.’?), 1 0 0 ~ . ( g ) charophyte oogonia (trochilircus sp.?). 63 x . ( h ) unidentified fossil (invertebrate?), 63 x . ( i ) charophyte oogonia (trochilrscus sp.’?), 63 x . ( j ) plant macrofossils, “hostirndla”. acanthodian scales and worm tubes 91 92 robert r . i l w table 1. stratigraphy of the devonian strata of spitsbergen (after blieck et al. 1987) mimerdal formation wijde bay formation grey hoek formation (eifelian) wood bay formation ( pragian-emsian) stjsrdalen division keltiefjeuet division kapp kjeldsen division sigurdfjellet division red bay group (fig. 2j) might consist of charophyte plant bodies. the plant material is, however, of the “hosfi mel1a”-type which lacks characters for proper identification. the paleoenvironment of the kapp kjeldsen division is not well understood at the present time. the kapp kjeldsen division is a faunal division based on agnathe and vertebrates which incorporate different lithologies. ranging from fine-grained red and green micaceous sandstones to coarser pebble conglomerates. this indicates different depositional environments. it has pre viously been interpreted as a pure freshwater deposit with no marine influence (friend 1965; friend & moody-stuart 1972). the association of leperditiid ostracods, charophyte oogonia, and worm tubesof the genus spirorbis in the bonebeds indicate, however, that at least parts of the kapp kjeldsen division have been deposited in brack ish water (d. vachard per. commun.). the co occurrence of different freshwater and brackish environments in the kapp kjeldsen division may be an indication of deposition in the lowland near the paleocoast where freshwater and brackish environments intertwined in at least parts of the depositional area (ilyes 1990). acknowledgements. 1 wish to thank j . valiukevicius from the lithuanian geological research institute. vilnius, for help with idcntification of the acanthodian scales. 1 also wish to thank d . vachard, universite des sciences et techniques de lille randreartois, france, for help with the microfacies analysis. references blieck, a . , goujet, d., & janvier. p. 1987: the vertebrate stratigraphy of the lower devonian (red bay group and wood bay formation) of spitsbergen. modern geol. 1 1 , 197-217. friend. p. f. 1961: the devonian stratigraphy of north and central vest-spitsbergen, proc. yorks. geol. soc. 33, 77 118. friend. p. f 1965: fluviatile sedimentary structures in the wood bay senes (devonian) of spitsbergen. sedimentology j, 39-68. friend. p. f. & moody-stuart, m. 1972: sedimentation i n the wood bay formation (devonian) of spitsbergen: regional analysis of a late orogenic basin norsk polorinsr. skr. 157. 1-77. llyes. r . r . 1990: agnathan and gnathostome fish from the kapp kjeldsen division, the wood bay fm. (lower devonian), spitshergen (in norwegian). unpubl. cand. scienl. thesis, universily of oslo. 161 pp. moy-thomas. i. a . & miles, r. s . 1971: palaeozoic fishes. chapmann and hall. london. 259 pp. 0 ~ g . t. 1967: some new acanthodian material from the lower devonian of europe. 1. l i n n . soc. ( z o o l . ) 4 7 ( 3 / 1 ) , 131-153. valiukevicius, j . j. 1979: acanthodian scales from the eifelian of spitsbergen. poleoniol. 1. 13(4), 482492. valiukevicius, i . i. 1985: akantody narovskogo gorizonta glavnogo devonskogo polja (acanthodians from the narva regional stage of the main devonian field). mokslas, vilnius. 143 pp. (in russian). the quaternary record of eastern svalbard an overview jon y. landvik, christian hjokt. jan mangerud, per moller and otto salvigsen landvik, j . y . , hjort, c., mangerud. j.. m d l e r , p. & salvigsen. 0. 1995: the quaternary record of eastern svalbard an overview. p o / a r research / 4 ( 2 ) , y5-103. the eastern part of the svalbard archipelago and the adjacent areas of the barents sea were subject to extensive erosion during the late weichselian glaciation. small remnants of older sediment successions have been preserved on edgeoya, whereas a more complete succession on kongsoya contains sediments from two different ice-free periods, both probably older than the early weichselian. ice movemeht indicators in the region suggest that the late weichselian ice radiated from a centre east of kong karls land. on bj~rnoya, on the edge of the barents shelf, the lack of raised shorelines o r glacial striae from the east indicates that the western parts of the ice sheet were thin during the late weichselian. the deglaciation of edgeoya and barentsoya occurred ca 10,300 bp as a response to calving of the marine-based portion of the ice sheet. atlantic water, which does not much influence the coasts of eastern svalbard today, penetrated the northwestern barents sea shortly after the deglaciation. at that time, the coastal environment was characterised by extensive longshore sediment transport and deposition of spits at the mouths of shallow palaeo-fjords. j o n y . l u n d o i k . the university courses o n svalbard ( u n i s ) , p . o . box 156. n-9170 longyearbyen, n o r w a y ; christian hjort and per moller, department of quaternary g e o l o g y . lund u n i ~ ~ e r s i t y , solvegatan 13, s-223 62 l u n d , sweden; jan mangerud, department of geology, university of bergen, alkgr. 4 1 , n 5007 bergen, n o r w a y ; o t t o saloigsen, norwegian polar institute, p . o. b o r 5072 majorsnra, n-0301 oslo, n o r w a y . introduction the quaternary geology of the svalbard archi pelago (fig. 1) has been the subject of extensive research during the last three decades. t h e inves tigations have concentrated in particular o n the largest island, spitsbergen (fig. 2), and models have been developed for the late quaternary glaciations (boulton 1979; miller 1982; landvik e t al. 1992a; mangerud & svendsen 1992), glacio isostatic rebound (schytt e t al. 1968; forman 1990; forman et al. 1995) and the holocene marine conditions of both svalbard and the adjac e n t seas (salvigsen et al. 1992). however. due to the more difficult accessibility, less progress has been made in understanding the quaternary geo logy of the eastern islands of the archipelago such as edgeoya, barentsaya and kong karls land (fig. 2). these islands, however, are critical for the understanding of the geology of the northern barents sea, and their geological history is fun damental for t h e development of regional models. a s a result of both the p o n a m programme (polar north atlantic margins. late cenozoic evolution) and hydrocarbon exploration in the barents sea, renewed interest has been expressed in the quaternary geology of the sea floor and the surrounding land mass. thus, the eastern islands of the svalbard archipelago can now con tribute towards an integrated understanding of the quaternary development along a profile from the central barents sea t o the continental shelf west of svalbard. in this paper we summarise the main results obtained from the p o n a m expeditions t o edgeoya. barentsaya, kongsoya and bjomoya, and use the new data t o compare and modify t h e present models of the quaternary history of svalbard and the barents sea. the late quaternary record the pre-late weichselircn sediments which record the late quaternary ice growth and decay have been preserved in several sections o n spitsbergen (boulton 1979; troitsky et al. 1979; miller 1982; miller et al. 1989; landvik et al. 1992a; mangerud & svendsen 1992; man gerud e t al. 1992) and an updated glaciation curve for the last intergiacial/glacial cycle of svalbard and the northern barents sea was recently sug gested by mangerud e t al. (1996), based o n cor relation of t h e different sediment successions. 96 j . y . landuik et al. these studies inferred from the spitsbergen sites that the northern barents sea was covered by ice sheets during most of the weichselian. except for two intervals at around 80 ka and 30-50 k a . t h e barents sea part of this reconstruction is based on the assumption that high relative sea levels during ice free periods on spitsbergen were caused by glacial loading in the northern barents sea. during the ponam expeditions. pre-late weichselian sediments were found on edgesya and on kong karls land (fig. 2 ) . o n northeastern edgesya. ice-free conditions are reflected by shell fragments embedded in beach sediments (bon devik et al. 1995). t h e fragments yield infinite radiocarbon ages. and mean amino acid ratios (aile/ile total) of 0.082 t0.019 (n = 6). these ratios are similar to those from the oldest ice free period on kongsoya (ingolfsson et al. 1995). which are postulated to b e of pre-eemian age. in visdalen on western edgeoya (fig. 2 ) . coarse-grained fan delta sediments were fig. i . regional map showing the main areas discussed in the text. the present oceanic surface circulation is indicated. deposited along the northern valley slope at a time when the seal level was > 5 7 m above the present, and these were later covered by sub glacial till (moller e t al. 1995). sub-till sediments have also been reported from the adjacent rosen bergdalen by boulton (1990). unfortunately. neither of these latter units could be dated. t h e islands of kong karls land (fig. 2 ) hold a key position with regard to understanding the last interglacial/glacial cycle of the northern barents sea. shells from svenskoya have been dated to 4 0 , 0 0 0 ~ ~ and older, and four drift wood logs from kongsoya were more than 40,000 years old (salvigsen 1981). o n e whalebone from eastern kongseya was dated to 33,600 ? 970 which was considered to be a minimum age by salvigsen (1981). from northwestern kongsoya, ingolfsson et al. (1995) report sediment suc cessions from two ice-free periods older than the late weichselian. biostratigraphical studies sug gest that the climate then was similar to or slightly warmer than the present (ingolfsson et al. 1995). quaternary record of eastern soalbard 80 i 1.5. 21' 4 97 fig. 2. deglaciation dates from edgeoya and barentscdya. the two oldest dates have been listed from most of the study areas. details are given in table 1 . the insert map also shows the location of kongsfjorden ( k ) , isfjorden ( i ) , van mijenfjorden (vm) and agardhbukta ( a ) . the glaciers on edgeoya and barentscdya are shaded. 98 j. i'. lardilik et al. t h e older period is characterised by amino acid ratios (aile/ile total) of 0 . w ? 0.009. and coin parison with the amino acid ratios in the eeniian deposits a t kapp ekholm (mangerud & svendsen 1992) and luminescence dates. both support a pre eemian age. the vounger period. with amino acid ratios of 0.043 ? 0.008. is interpreted to be of either earlv weichselian or eemian age (ingolfs son e t al. 1995). several scenarios for the progression of the last interglacial/glacial cycle of svalbard and the northern barents sea have been suggested (lindner et al. 1984; larsen et al. 1991; landvik et al. 1997a: mangerud x r svendsen 1992; man gerud e t al. 1996). through time, these models have evolved a better foundation for recon structing the area of the barents sea proper. previous models (larsen e t al. 1991; mangerud & svendsen 1992) suggested almost contem poraneous glacials and interstadials over spits bergen and the barents sea. whereas the later ones (landvik et al. 1992a; mangerud e t al. 1996) suggest a long period of ice cover over the sea to the east of the svalbard islands during the early weichselian. if the younger ice-free period o n k o n g s ~ y a (ingolfsson e t al. 1995) is of an early weichselian age. we assumed that the whole bar ents sea must have been deglaciated. however, the time control so far is t o o rough to justify any revision of the latest models (mangerud et al. 1996) for the last interglacial/glacial cycle of the svalbard/barents sea region. the d w r r m i c s of rlw l o r p weichselian ire sheet the extent of the ice sheet over svalbard and the barents sea during the late weichselian has been the subject for debate for three decades ( e . g . schvtt et al. 1y68; boulton 1979: salvigsen 1981; mangerud et al. 1992; elverhai et al. 1993). based on the post glacial uplift pattern (salvigsen 1981; forman 1990). and the distribution of sea floor sediments. moraine ridges. and subglacially formed flutes ( e h e r h s i ct al. 1993). there is a consensus today that the ice sheet covered at least the northern barents s e a . for a short period. outlet glaciers a d w n c e d to the continental shelf \vest o f spitsbergen (manperud et al. 1992; svend sen rt :it. 1992) and to the western barents sea shelf (elverhmi et al. 1993). recent models of ice sheet extent based on uplift data also suggest that the ice sheet extended to the shelf edge to the west and north o f svalbard (lambeck 1995,1996). however, less is known about the exact timing and dynamics of t h e ice sheet. t h e pattern of glacioisostatic rebound shows a centre of maximum uplift in the northern part of the barents sea (schytt e t al. 1968; forman 1990). bondevik et al. (1995) present detailed relative sealevel curves from e d g e ~ y a and b a r e n t s ~ y a , and their revised isobase m a p for 10,000 "'c years bp suggest a centre of uplift southeast of kong karls land (fig. 2). this compares with the iso static models of lambeck (1995, 1996) who also suggested that t h e ice sheet had its maximum ice thickness southeast of kongsaya. glaciological modelling of the ice sheet (siegert & dowdeswell 1995) suggests a similar location for the maximum ice thickness. based on reconstructions of ice flow directions, it has been suggested that the svalbard and barents sea ice sheet consisted o f several confluent ice domes and not only o n e single ice d o m e centered over the barents sea (landvik & salvigsen 1985; mangerud et al. 1992). however, this ice flow pattern may represent only phases of growth. or decay, of t h e ice sheet. in the peripheral region of the former ice sheet, ice streams have been shown to drain along the b j s r n a y a and storfjorden troughs o n the barents shelf (elverhoi et al. 1993), and along van mijenfjorden and isfjorden o n spitsbergen (man gerud e t al. 1992). different sets of ice movement indicators (see review by salvigsen e t al. 1995) show phases when ice flow radiated from a centre east of svalbard. evidence for an ice sheet centred east of kong karls land is also found on kongs s v a . where the sediments from the younger ice free period were deformed by a topographically independent glacier moving from the northeast (ingolfsson et al. 1995). even if these sediments are of a n early weichselian age, we assume that such an ice movement must be attributed to the large late weichselian ice sheet. on a larger scale, there is a systematic variation in the sediment distribution on the barents sea floor that fits the theoretical zonation of glacial erosion and deposition under an ice sheet as pro posed by sugden (1977,1978). t h e shallow banks north of 74". where bedrock is exposed over ca 5 0 % of the area and sediment thickness is <25 ni (solheim & kristoffersen 1984), can be ascribed to a zone of erosion. this contrasts with the zone of deposition t o the southwest, where large sedimentary wedges increase in thickness towards the shelf margin, e.g. in the b j ~ r n 0yrenna and storfjordrenna troughs (solheim & quuternary record of eastern siialb~itd 99 kristoffersen 1984; vorren e t al. 1990). also the distribution of pre-late weichselian sediments on the svalbard islands fits such a model. as reported here. edgeoya and barentsoya were subjected t o extensive glacial erosion during the last glaciation, whereas most sediment accumu lations of pre-late weichselian age are found o n western spitsbergen (landvik & salvigsen 1985; miller et al. 1989; lonne & mangerud 1991; landvik et al. 1992a; mangerud & svendsen 1992). several of these accumulations are in glac ially-shaped fjord and valley basins or on the strandflat, and show that the late weichselian glacial erosion was probably less important in forming the glacial topography of western spits bergen, the late weicliselian deglaciation the western margin of the barents ice sheet reached the shelf break to the west during the late weichselian (elverhoi e t al. 1993; mangerud et al. 1992), and the glacier must also have sur rounded or covered bjqrnqya o n the south western margin of spitsbergenbanken. as indicated by many radiocarbon dates, the ice sheet started to recede from the outer coast of spitsbergen at 13,000 bp (forman 1990; man gerud e t al. 1992), whereas the central fjord region first became ice free ca 10,000 bp (man gerud e t al. 1992). from the eastern part of the archipelago, the timing of the deglaciation had before the p o n a m expeditions been based on only a few dates from edgeoya and barentsoya (knape 1971: nagy 1984; forman 1990) and from kongsoya (salvigsen 1981). there were n o satis factory date$ for the deglaciation of b j o r n ~ y a until the studies of wohlfarth et al. (1995). dating of the local deglaciation has been an aim of the p o n a m studies, and a regionally well distributed set of new dates from edgeoya and b a r e n t s ~ y a is now available (table 1, fig. 2). these indicate a contemporaneous deglaciation at around 1 0 , 3 0 0 ~ ~ along both the eastern and western coasts of the islands. however, dating of the oldest part of the sea level curves from the area (bondevik e t al. 1995), indicates that the deglaciation occurred ca 500 radiocarbon years later. t h e deglaciation probably progressed by rapid calving in both storfjorden and olgastretet (fig. 2), and remnants of the glacier remained in the interior of spitsbergen (mangerud et al. 1992) and edgeoya (landvik e t al. 1992b; moller e t al. 1995). w e assume that the rapid emergence between 10,000 and 9000 bp. (salvigsen 1981; bondevik e t al. 1995) is as a response to a major unloading just prior t o 1 0 , 0 0 0 ~ ~ . the cor respondence in time between the deglaciation dates of ca 10,000 b p for both agardhbukta (fig. 2) o n the western side of storfjorden (salvigsen & mangerud 1991) and o n k o n g s ~ y a (salvigsen 1981) also suggests that the marine part of the ice sheet vanished d u e to rapid calving. a t this time, the nature of the ice flow across high areas thus changed from being regionally governed by the configuration of the barents ice sheet, to being more locally affected by the topography beneath the last ice remnants on the islands. o n b j ~ r n o y a (fig. l), glacial striae reflect only a local ice cap centred on the southern and middle part of the island (salvigsen & slettemark 1995). the ice cap may also have been a remnant of the ice sheet, formed by rapid withdrawal of the western margin of the barents ice sheet. basal dates from lake sediments on the island show that most of the local glaciers had vanished before 9800 bp (wohlfarth e t al. 1995). the holocene the sediment records of edgeoya and b a r e n t s ~ y a show that the physical environment at the weichselian/holocene transition was different from today. t h e large transverse ridges found at the mouths of several valleys were interpreted by biidel (1968) t o have been formed by longshore currents. they were later reinterpreted by nagy (1984) as ice contact deltas, and taken as evidence for a halt in the deglaciation, called the “visdalen event”. new investigations of the sediment suc cessions in visdalen o n edgecdya (fig. 2 ) (moller e t al. 1995) support biidel’s view, and show that thick piles of sediments were deposited as fan deltas which also fed longshore currents, depositing large ridge-formed spits at the mouths of inundated valleys between 10,000 and 9000 bp. t h e elevations of other similar ridges at the mouths of shallow paleo-fjords on e d g e ~ y a and barentsoya, suggest that these are of the same age as the o n e in visdalen. the formation of large spits (miiller et al. 1995) during a period of rapid regression (bondevik et al. 1995), suggests that the longshore sediment transport during the preboreal was considerably greater than today. in the situation immediately following t h e deglaciation, we assume that uncon ly 7 5 ) f ra n kc n h a lv a va k dp p z ic h cn lla d a lc n h u m h b li fj o rd d a lc n a lh rc ch th rc cn d ia n a d a le n d yr d a le n g u ld a le n s rn el le da lc n r a d d e d a le n v is d a le n t a la ve ra 7x 03 4' n 2 1" 20 'f . 78 '33 " ?1 "5 x 'e 7x "l l' n 2 i" ss 'e 7h "i: 'n 23 "( w i'e 77 "s y )'n 2 2" s y 'e 7 7 "5 7 'n 2 3y 15 'e 77 % " 23 "l h' e 77 04 5" 22 "4 5' e 7 7 "5 3 'n 2 1" 3y 'e 7 7 5 7 " 22 "z x 'e 78 "0 0' n 21 "3 6' e 7 8 "0 3 'n 2 1 "i s 'e 7 8 "1 5 'n 2 1" 07 'e io .2 65 2 y s 94 50 t i i 0 y 61 5 5 11 11 ys o 5 2 7( 1 x 77 (1 i 5 0 yx xs 5 13 (1 96 20 -c 13 11 l( 1. 33 0 -c i l (1 ys yo f y ii y 40 5 2 71 1 03 60 f l (1 5 10 .2 (m l % y 5 95 9. 5 t 1 05 9 x4 0 t 1 30 y 70 5 ? 1 35 96 75 2 50 yy yo ? 80 10 .0 15 l r 75 95 65 c 8 0 l( l. ly 0 f 3 20 98 20 f 1 30 98 10 2 2 00 10 .3 70 lr 60 x 777 6 x 777 11 x7 -x 1 5 x x -2 m i (1 b i ih x x -s ?s a x x -5 27 xx -5 x3 xx -5 6x x 7 -x l( l x 7x o 6 x 670 6 x 670 5 xx -7 37 86 -4 18 x 6 4 2 ( ) g b x s 8 6 -5 7 2 a 86 .5 72 8 88 -6 75 87 -7 02 g b 12 3 a a r -9 0 8 a a r -8 38 s r r -2 2 0 4 i. a n d vr k c i a l (1 99 2h ) la nd vr k ct a l. ( iy 9 2 h ) u m d c v ik c i ;ii (l y y 5) b on dc vi k c t ;ii (l y y 5 ) f or rn un ( 1 0 9 0 ) h o n d e vi k c t at . (1 99 5) h o n d cv ik c t al . (1 9 9 5 ) l a n d vi k ct a l. (i y y z h ) l a n d vi k ct a l. ( 1 9 9 2 h ) r o n n cr t d l .;i nd vi k ( iy y 3) k o n n cr i d l .; in dv ik (1 99 3) ih in d e vi k c t a l. ( ly y 5 ) d o n d cv ik e t al . (1 99 5) a d ri cl ss o n e t a l. ( iy y z h) h a n se n & k n u d se n ( iy y s ) h a n sc n & k n u d rc n ( 1 9 9 5 ) f vr rn a n ( iy y o ) b o n d cv ik c t al . (l y 9 5 ) b o n d e vi k c t a l. (1 99 5) n ag y (1 9 8 4 ) m ti ll e r et a l. ( 19 95 ) m o ll e r e t al . ( 19 95 ) f o rr n a n ( 19 90 ) quaternary record of eastern svalbard 101 solidated glacial sediments deposited on unstable slopes were the most important source for the sediments deposited i n the alluvial fans and fan deltas. the latter process may have been enhanced by an early holocene hydrographic regime which was different from the present. the svalbard waters experienced a stronger influx of atlantic water during the early and middle holocene as reflected by the influx of thermo philous molluscs already around 9500 bp (sal vigsen et al. 1992). however, a detailed preboreal climatic record based on foraminifera from raised glacimarine deposits at eastern edgeoya suggests that the steady amelioration of the marine con ditions was interrupted by a short cooling between 9600 and 9 4 0 0 ~ ~ (hansen & knudsen 1995). from findings of subfossil mytilus edulis, a mini mum age of 8 8 0 0 ~ ~ was obtained for the first major influx of atlantic water reaching edgecbya (hjort et al. 1995). this shows that the circulation in the northwestern part of the barents sea was different during the early holocene, and it poss ibly may also have influenced the strength and pattern of the near-shore currents in the area. at the same time, during the preboral, the glaciers on edgeoya receded beyond their present limits (ronnert & landvik 1993) and the modern flora of the area was established (bennike & hedenas 1995). most glacier margins i n the area are today characterised by the retreat from young moraines formed by stacking of sheets of sedi ments during the little ice age (adrielsson et al. 1992; ronnert & landvik 1993; dowdeswell & bamber 1995). conclusions the collaborative efforts during the ponam expeditions to eastern svalbard and bjorncbya resulted in a new understanding of the geological development of this part of the svalbard archi pelago and the barents sea. the main results are summarised below. 1. glacial erosion during the late weichselian removed most of the older sediments from the eastern parts of the svalbard archipelago and adjacent parts of the barents sea. the erosion i n this region was more extensive than on the western coast of spitsbergen. where several older sediment successions have been preserved. 2. deposits from two pre-late weichselian periods, with climates similar to or slightly warmer than the present on kong karls land, show periods when the barents sea was corn pletely deglaciated. 3. both the improved isobase reconstructions and isostatic modelling suggest that the late weichselian ice sheet had its maximum thicknes, southeast of kong karls land. 4. detailed relative sea level curves from e d g e ~ y a and barentsaya show that the glacio isostatic uplift 10,000-9000 bp was rapid, responding to a major unloading just prior to 5. during t h e last deglaciation, the marine based part of the ice sheet over eastern svalbard underwent rapid calving, and most of the glacier fronts receded beyond the present day coasts of e d g e ~ y a and barentscbya before 10,300 bp. 6. the coastal environment immediately after the deglaciation was characterised by extensive longshore sediment transport. large spit ridges were formed at the mouths of several valleys. 7 . subfossil mytilus edulis indicate a major influx of atlantic water into the northwestern barents sea between ca 8800 and so00 bp. 10,000 bp. acknowkdgemeni.s. this paper is mainly the result of the expeditions within the ponam (polar north atlantic margins. late cenozoic evolution) programme in i y y i and 1993. fund ing for the fieldwork was provided by the research councils in denmark, norway, sweden and the u . k . , as well as by the participants own institutions. the norwegian group also received financial support from norsk hydro. saga petroicurn. statoil and the norwegian petroleum directorate. and the swedish group from the polar research secretariat helicopter transport in the field was made possible by a grant from the european commission to the european science foundation the norwegian polar institute provided log~stic support, and the use of r / v lance during initial reconnaissance work and for transport to and from eastern svalbard. norwegian polar institute expedition leaders t . siggerud (1991) and j. hdugland (1993) were most helpful to the two ponam expeditions. i n 1991, b. torgerhagen (pilof) and k. nilsen (engineer) skillfully operated the helicopter from a base camp at kapp lee a t edgeoya. h . eggenfellnet assisted in base operations. the norwegian coast guard transported two field parties to bjornoya in 1993. all operattons in eastern svalbard werc made possible through kind permissions from the governor on svalbard, who also assisted with helicopter transport from kongsoya in 1993. to all these persons and institutions we offer our sincere thanks anally. all parttctpants in the ponam project are thanked for the open communication. and all the lively discussions that have contributed to the results we sec today. references adnelsson, l , johansson. k & hjort, c 1992 deglaciation and holocene stratigraphy tn a llttle ice age comporite 102 j . y . lnndiiik er al nioriiinc i n tront nt seidbrecn. edgeoyd. edstern stalbard. liindqii(i r e p . 3.7. 15.7-1mi bennikc. 0 b h e d e n ~ s . l 1yy5: earl! holocene land floras m d faun;i, troni edeco!cl. eaztcrn s\alhard. pulur r n . l j f 2 j . 205-2 i4 b o n d e \ i k . 5 . . mangerud. j . ronncrt. l 8: salvigscn. 0. 1995. postgld~iiil rea le\cl histor! of edgeo!a and barentsoya. enatern s\,ilhdrd p d i i r r r ~ e i r r ~ i i i j f 2 j . 153-180. boulton. c; s . l y 7 y : glucial history o f the spit5hergen archi pclagi, and the problem n f d bdrent\ shelf ice sheet. borefir 8. 31-i: boulton (i s. iyyo: sedimentar! dnd ,ca le\el change5 during glacial c\cle\ and their control on rlacimarine facie, archi tecture. pp 15-52 i n dowdest\ell. j . a 8: scourse. j d. 1 e d \ 1. ~ ; / ~ i ~ i i i i i i r i i i r c'iii'iruiimriits p r o i r s s r i o i i r l sediineiio gcoi snc spec puhl 53 budel. j i y h s . d i e luiigc landhehung spitrhergens im l'mkreis dc\ frecni,in-sundc\ und der olga-sirasre w r r r o h . grogr. arh. 1-7 1 . 1-21 d w d e s \ r i . l l . j ,a 6 banihcr. j l l y y 5 : on thc glaciology ol t . d g e d \ a ,tiid b.ircntw!a. s\ulhard polor res. 14f21. lil5 1 2 2 f~eld\ka,ir. l\' . solheini. a . s f l m d berg. 51 h. ku\.uurm. 1. lyy3. 1 h ~ barent\ sea ice sheet ,a model ( 1 1 i t \ g i o \ \ t h dnd dec'i! during the l a \ t ice maxiniuni q i u r r \ t i kt.1. 1 2 . xh.lx7i. f{,rni'in. \ i y y i i . p o ~ t g l ; i c i a l rciati\c w a l c \ e l hictor! ot north nestern spihbergen. s\albard grol. so<. am. brill. / 0 2 , i . ~ ~ i ~ i ? y i ~ t i i r i n d n . \ . l u h i n k i . d . m i l l e r . g . h . . sn!der. i . 5ldtisho\. ( i . k i i r w n . s. & 5l!\li\ct5. \' i y y j . po,tglacial emergencc dnci di\trihutitm ( i f l a i c h'eich\c'lian ice-theet loads in the northcrn b a r e n h and k a r . ~ s u \ . kursia. geol. 23. 112-1 i6 h a m c i i . a ti k n u d w n . k . l . iy95. kccent foraminifera1 di\trihutiun i n freemansundct and earl! lfolocene <ira tigraph! on edgeoya s\:ilhard polor hrr. 1412). 315-238. h l o r t . c . . xlangcrud 1 . a d r i c l v o n . l.. bondebik. s.. landvik. . i . y & siil\igscn. 0 i y 9 i . radiocarhon dated common niu\sci\ . m i i r / t i . \ cdrrirr t r n m eajtern svalhard and the ilnlcrcenc miirinc climiitic optimum polnr re\. /4f?j. 23') 74.3 ing6lfswn. 0 . rognvald\son. f . . bergsten. h . . hedenas. l.. lcmdahl. (i l . l i r i o . j m. b sejrup. h. p. ipy5: l.ite ouaternar! glacial and eii\ironincntal hiaton o f k o n p y a . s\alhard polur rrseurdi i j 1 2 r . 123-139. knape p. 1y71 c-14 dateringar a\ hhjdd strandlinjcr. s\nkrond p i m p \ t e n m \ aer uch i d k t r a g e l w r av hogsta kustlinjen pa sval hard unpuhlizhed fil jr thc\ir. l;ni\er\it! of stockhnlni 1-14? amheck. k lyy5. conrtraint\ o n the laic \t'cich\clian ice 5hcct ewer t h e barentr se,i troni d%ervation\ ot raiscd \horc liner quur scr her. l j . 1-16 .amheck. k 1996: limits o n the areal extent o f the barents sea ice sheet in late weichselian time glohal plniierar\ c ' h ~ i g r 17 ( i n prcss) and\ih. i \ b salvigrcn. 0 l y 8 5 . glaciation development idial wa-lc\cl on ccntrdl spitrhergcn. s\allxird l a n d \ i k . j . j' . bolstad. ,m , l.!chc. a . k . mangerud. j 6 sejrup. t l . p i y y l a u'cichwlian \tr;itigraph! and polaeo e n \ i r o n m c n l \ a t b r l l \ u n d . \ve\tcrn s t a l h a r d . burerrs 21. 33% i 5 h landxih. . i . y . ilansen. a . kell!. m . sdhigscn. 0 . slette n ~ i r h . c ) . s. stuhdrup. 0 p . i9y2h: 'the last dcglaciation e l \ c r h m a p o / n ~ ra5. i ii.! 1-111 and glacimarinc/marinc sedimentation on barentssya and edgeoya. eastern svalhard. lui~dqrtn r e p . .?s. 61-83. larsen. e . sejrup, h . p . . olsen. l . & miller. g . h . 1991: late quaternary land ~ acii interactions: fcnnoscandia and svalhard the nordic seas q u a . lnr. 10-12. 151-15'). lindner. l . blarks. l & pekala, k . 1984: late quaternary glacial episodes in the hornsund region of spitshergen. boreris 13. 35-47. lonne. i . 8: mangerud. j . 1991: an early o r middle wcich aelian sequence of proglacial, shallow marine sediments on uestcrn s v a l h a r d . b o r r n i 20. 85-104. mangerud. j . 8: gulliksen. s 197.5: apparent radiocarhon ages of rccciit marine shells f r o m norway. spitshergcn, and arctic canada qunr. r r s . s. 26.%273 hlangerud. j . & sveiidscn. j . 1. iyy?: the last intcrglacial glacial period o n spitshergen. svalhard. qaur. sci. r r o . 11. hlul6m. mangerud. j . . bolstad. m . . elgersma. a . . helliksen. d . . land \ i k . j y . . lenne. i . lycke. a . k . . salvigsen. 0.. srrndahl. 1. & svendsen. j . 1. 1992: t h e last glaclal niaxiiiiuni on spitsbergen. svalbard. quirt. res. 38. 1-31 mangerud. j . . jannen. e . & landvik. j. y. lyy6: late cenozoic histor! o f the scandinavian and barents sea ice yheets. glohol plurirrarv cliungr. 12 ( i n press). m i l l e r . g . i i . 1982: quaternary depositional episode\. westcrn spitshergen. norwsayamino\tratigraphv and glacial hi\tnry. a r c r . a i p . rrs. 14. 321-34i) miller. g . i f . . sejrup. h . p , lehman. s. j . & forinan. s l. 1984: glacial history and marine environmental change dur ing the last interglacial-glacial cyclc. western spitahergen. svalbard. borros 18. 273-296. moller. p . . stuhdrup. 0. p . & kronborg. c. 1095: l a t e weich selian io early holocene sedimentation in a steep tjord/ \allc! setting. visdalen. edgcsya. ea\tern svalbard: glacial depows. ~lluvial/colluvial-fan deltas and spit-platform% polur res. l j ( 2 ~ . 181-203. nag!. j . 1y84: outernary glaciomarine deposits and fora minifera trorn edgeova. svalbard. b o r e a s i.?. 319-332. ronnert. l. 8: l m d v i k . j . y . 1993: holocene glacial advances and moraine formation at alhrechtbreen, edgeova. svalhard. polor res. 1 2 . 57-63. salvigsen. 0 . 19x1: radiocarhon dated raised heaches in kong karl\ land. svalbard. and their consequences for the glacial hi\tor) o f the bdrents sea. g r o r g r . anri 6 3 a . 283-2511, salvigscn. 0 & mangerud. j. l 9 y l : holocene shoreline dis placement at a g x d h h u k t a . spithbergen. svalbard. polrrr r e s . '1. 1-7. sahigscn. 0.. forman. s . b m i l l e r . g . h . 1992: thermophilous m o l l u ~ c s on svalhard during the holocene and their paleo climatic implications. poiiir rrs. i / . 11-10. salvigsen. 0. & slettemark. 0. 1995: past glaciation and sea levels on b j @ r n ~ y a , svalbard. polur rrs. 14(2). 2.15 1.7 i salvigsen. 0.. adriclsson. l . i i j o r t . c.. kelly. m.. landvik. j y b konncrt. 1.. 1995: dynamics o f the la\t glaciation of eastern svalbard inferred from glacier-movement indicators. polirr res. i d ( ? ) . 141-152 sch)tt v . . hoppc g.. blake w . . jr. & grosswald m . g 1968: the extent o f thc w u r m glaciation in the european arctic. a preliiiiinary report about the stockholm univeraity svalhaid expedition 1966. /firrrirariona[ socirn, of scientific h y d r o l o g ! . geiieral .4ssemb/y i n bern 1967, pirbl. rio. 207 216 siegert. m. j . 61 diiwdeswell. j . a . 1995: numerical modelling quaternary record of eastern siialbnrtl 103 of thc ldtc weichselian svalbard-barents sea icc sheet. year. res. 43. 1-13. solhelm, a . & kriatoffersen. y . 1984: the physical environ ment western barents sea, 1 : 1,500.000. sediments above the upper regional unconformity: thickness, seismlc stratigraphy and outline of the glacial history. norsk polurinsf. skr. 1798. 1-26. sugden, d. e. 1977: reconstruction of the morphology. dynamics, and thermal characteristics of the laurentide ice shcet at its maximum. arct. alp. res. 9 , 21-47. sugden. d . e. 1978: glacial erosion by the laurentide ice shcet. j . ghciol. 20. 367-391. svendsen. j . 1.. mangerud, j . , elverhoi. a , . solhcim, a . & schiittenhelm, r. t. e . 1992: the late weichsclian glacial maximum on western spitsbergen inferred from offshore sediment cores. marine geology 104. 1-17 troitsky, l., punning, j . m . . hiitt. g . & rajamar. r . 1979: pleistocene glaciation chronology of spitsbergen. boreus 8 , 40 1-407. vorren t. 0.. lebcsbye e. & larsen k . b . 1990: gcometry and genesis of the glacigenic sediments in the southern barents sea. pp. 269-288 in dowdeswell j . a . & scourse j . d. (eds ): glacimaririe enoironments: processes und seditrrenrs. the geological society special publication. london. wohlfarth, b.. lemdahl, g , olsson. s., persson. t ,snowball. i . , king, j . & jones, v. 1995: early holocene environment on bj~rncbya (svalhard) inferred from multidisiplinary lakc sediment studies. polar research 1 4 ( 2 ) , 253-175. smoking guns and volcanic ash: the importance of sparse tephras in greenland ice cores research article smoking guns and volcanic ash: the importance of sparse tephras in greenland ice cores gill plunkett,1 michael sigl,2 jonathan r. pilcher,1 joseph r. mcconnell,3 nathan chellman,3 j.p. steffensen4 & ulf büntgen5,6,7,8 1archaeology and palaeoecology, school of natural and built environment, queen’s university belfast, northern ireland, uk; 2climate and environmental physics, physics institute & oeschger centre for climate change research, university of bern, bern, switzerland; 3division of hydrological sciences, desert research institute, reno, nv, usa; 4centre for ice and climate, university of copenhagen, copenhagen, denmark; 5department of geography, university of cambridge, cambridge, uk; 6swiss federal research institute wsl, birmensdorf, switzerland; 7global change research centre (czechglobe), brno, czech republic; 8department of geography, faculty of science, masaryk university, brno, czech republic abstract volcanic ash (fine-grained tephra) within greenland ice cores can complement the understanding of past volcanism and its environmental and societal impacts. the presence of ash in sparse concentrations in the ice raises questions about whether such material represents primary ashfall in greenland or resuspended (remobilized) material from continental areas. in this article, we investigate this issue by examining tephra content in quasi-annual samples from two greenland ice cores during a period of ca. 20 years and considering their relationships with sulphur and particulate data from the same cores. we focus on the interval 815–835 ce as it encompasses a phase (818–822 ce) of heightened volcanogenic sulphur previously ascribed to an eruption of katla, iceland. we find that tephra is a frequent but not continuous feature within the ice, unlike similarly sized particulate matter. a solitary ash shard whose major element geochemistry is consistent with katla corroborates the attribution of the 822±1 ce sulphur peak to this source, clearly showing that a single shard can signify primary ashfall. other tephras are present in similarly low abundances, but their geochemistries are less certainly attributable to specific sources. although these tephra shards tend to coincide with elevated sulphur and fine (<10 µm) particulates, they are not associated with increased coarse (>10 µm) particle concentrations that might be expected if the shards had been transported by dust storms. we conclude that the sparse shards derive from primary ashfall, and we argue that low tephra concentrations should not be dismissed as insignificant. keywords primary ashfall; resuspended volcanic ash; volcanic eruptions; katla; dust storms; tephrochronology abbreviations ce: christian era grip: greenland ice core project ky: thousands of years neem: north greenland eemian ice drilling research project citation: polar research 2020, 39, 3511, http://dx.doi.org/10.33265/polar.v39.3511 copyright: polar research 2020. © 2020 g. plunkett et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 08 june 2020 competing interests and funding: the authors report no conflict of interest. the neem project is supported by funding agencies and institutions in belgium (fund for scientific research—french-speaking community and research foundation—flanders), canada (natural resources canada/geological survey of canada), china (chinese academy of sciences), denmark (agency for science and higher education), france (paul-emile victor french polar institute, french national centre for scientific research/national institute for earth sciences and astronomy, french alternative energies and atomic energy commission and french national research agency), germany (the alfred wegener institute), iceland (rannis—the icelandic centre for research), japan (national institute of polar research), korea (korean polar research institute), the netherlands (dutch research council/earth and life sciences division), sweden (swedish research council), switzerland (swiss national science foundation), the united kingdom (natural environment research centre) and the usa (us national science foundation, office of polar programs). collection and primary chemical analyses of the neem-2011-s1 and tunu2013 cores was funded by the us national science foundation grants 0909541, 1023672 and 1204176 to jrm. ms has received funding from the european research council under the european union’s horizon 2020 research and innovation programme (grant agreement no. 820047). ub received funding from the programme sustes—adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (cz.02.1.01/0.0/0.0/16_019/0000797). trace element analysis was partly funded by a quaternary research fund award to gp from the quaternary research association. correspondence to: gill plunkett, archaeology and palaeoecology, school of natural and built environment, queen’s university belfast, belfast bt7 1nn, northern ireland, uk. e-mail: g.plunkett@qub.ac.uk. to access the supplementary material, please visit the article landing page introduction in recent years, evidence for past volcanic impacts on climate variation and societal transformation has increasingly been posited (esper et al. 2013; sigl et al. 2015; stoffel et al. 2015; büntgen et al. 2016). the climate effectiveness of eruptions stems from the capacity of material injected into the stratosphere, particularly sulphur-containing gases that convert to sulphate aerosols, to deflect incoming solar radiation over the course of weeks to years, triggering surface cooling (robock 2000), although ash particles may offset the cooling in some instances (flanner et al. 2014). volcanic eruptions vary greatly in their magnitude, duration and type of emission, and their latitudinal location is also a significant factor in the potential extent of their atmospheric impact (toohey et al. 2019). as volcanic eruptions occur globally on a continual basis, including several that penetrate stratospheric levels each decade, it remains to be established which types of events pose the greatest risk to the climate system. the understanding of past volcanic impacts hinges substantially on the polar ice core records that present an extended history of volcanic activity through their chemistry, most notably of eruptions that emitted sufficient aerosols to have potentially impacted the earth’s radiative balance (hammer et al. 1980; zielinski et al. 1994; sigl et al. 2013). for the late holocene, ice cores offer a level of chronological precision that enables their records to be reconciled with historical events, allowing climate perturbations and any ensuing societal impacts to be evaluated (sigl et al. 2015; büntgen et al. 2016). identifying the source eruption is key to deciphering the volcanic processes that impact the climate system. for example, atmospheric loading of volcanic aerosols is best reconstructed if the latitude, other eruption parameters (e.g., plume height, eruption style) and season are known. however, in many regions, observational records of eruptions began only in recent centuries, and volcanic histories remain very poorly resolved in many regions (siebert et al. 2011). furthermore, secure attribution of volcanic signals to specific eruptions can only be achieved through the analysis of associated volcanic ash (fine-grained tephra) particles whose glass geochemical composition may point to the source eruption, volcano or volcanic region. transport of volcanic ash to polar regions is constrained by several factors, however, not least injection height, meteorological conditions at the time of the eruption over both the source volcano and the deposition site, and general atmospheric circulation patterns. given these limitations, it is perhaps not surprising that concentrations of ash particles large enough (usually >20 µm) to be geochemically typed by using standard tephra-analytical techniques in polar ice are frequently low (iverson et al. 2017). for late holocene greenland ice, coulter et al. (2012) examined multi-annual samples with as few as one tephra shard identifiable by using light microscopy, while other studies have been limited to analysing particles <10 µm by using sub-optimal techniques for geochemical characterization (palais et al. 1992; zielinski et al. 1997; barbante et al. 2013). such a very fine-grained material might not be recognizable as volcanic glass by using standard optical microscopy for routine tephra screening. a major concern relating to sparse cryptotephras in polar ice is whether they represent primary ashfall or reworked (secondary) material. prevailing wind patterns, the high latitude and altitude of the ice core sampling locations and the specific environmental conditions required to resuspend ash from older deposits are amongst the leading factors that mitigate the incorporation of reworked tephra into the ice. nevertheless, it is conceivable that strong dust storms could transport resuspended sediment, including tephra, over long distances to polar areas. aeolian resuspension of ash is especially likely in areas where pedogenesis and stabilization by vegetation cover are retarded or absent, namely in very cold or very arid regions. in the valley of the ten thousand smokes, alaska, for instance, tephra beds from the 1912 novarupta eruption remain exposed as climate and topography combine to hinder the establishment of pioneering vegetation (hildreth & fierstein 2012). under certain wind conditions, ash from these beds can be resuspended and elevated as much as 3 km into the atmosphere, equivalent to a plume from a vulcanian-style eruption and sufficient to enable ash to be dispersed over several thousand kilometres (hadley et al. 2004). how then do we differentiate primary ashfall from dust deposition events incorporating remobilized tephra? although reworked glass can sometimes be evidenced by rounded edges, corrosion or altered major element geochemistries (lowe 2011), these indices may depend upon factors such as the length of time a tephra has been exposed to weathering prior to remobilization, or transport mechanisms. low analytical totals in geochemical analyses can also result from post-deposition hydration of the glass under exposed conditions, although other factors contributing to low totals include thin glass walls and instrumental error (froggatt 1992; hunt & hill 1993). in terms of the potential source area of reworked volcanic material reaching greenland, we might reasonably assume a correlation with the sources of fine particulate matter in the ice that regularly reaches polar locations. strontium (sr) and neodymium (nd) isotope analyses of <5 µm particles in high-altitude greenland ice cores indicate a predominantly east asian origin (bory et al. 2002; bory et al. 2003), although others propose that a north african source may be underestimated in these studies (tanaka & chiba 2006; lupker et al. 2010). winter atmospheric circulation over both the greenland neem and tunu ice-core drilling sites is dominated by the polar vortex. in spring to summer, air masses over both sites originate mainly from the west, but both sites are also influenced by air masses from the north atlantic, arriving at neem from the south and at tunu from the north-east and south-east (steen-larsen et al. 2011; maselli et al. 2017). with the exception of iceland and the jan mayen islands (whose tephras are geochemically well-characterized), however, these regions do not feature unconsolidated ash beds from which reworked tephra could derive. in iceland, dust remobilization also occurs predominantly in spring and early summer and, from southern iceland at least, dust is mainly transported southwards (prospero et al. 2012). on balance, it seems that the most probable sources of reworked tephra that might reach greenland will lie to the west. how meaningful, therefore, are sparse tephra particles recorded in the ice? do occasional shards merely reflect a background signal of remobilized ash particles or can they represent primary ashfall? to address these questions, we consider a ca. 20-year interval of ice from two northern greenland ice cores—neem-2011-s1 and tunu2013 (fig. 1)—to investigate the frequency and origin of volcanic ash in the records, and their relationship to other volcanogenic proxies. fig. 1  location of neem and tunu2013 coring sites (stars) with respect to volcanic sources (squares) referred to in the text. the locations of sites in which cryptotephra of similar major element geochemical glass composition to qub-1880 are also indicated (circles; see plunkett & pilcher 2018 for a discussion of these tephras). materials and methods sulphur concentrations from the tunu2013 and neem-2010-s1 greenland ice cores have previously been reported (sigl et al. 2013; sigl et al. 2015). for the tunu2013 core, fine particulate matter was measured for two fractions (2.6–4.5 µm, 4.5–9.5 µm) during continuous flow analysis of an adjacent parallel melter stick from the core (ruth et al. 2003; sigl et al. 2013; jensen et al. 2014). we examined sections of ice from both cores spanning the period from about 815 ce to about 835 ce, encompassing an extended volcanogenic acid signal between 818 and 822 ce (büntgen et al. 2017). constrained at the 774 ce cosmogenic event (miyake et al. 2012), both chronologies have an error of ±1 year in this interval (sigl et al. 2015). in total, 4.42 m of ice from neem-2010-s1 and 2.01 m from tunu2013 were subsampled at approximately annual resolution, comprising 40 individual samples. samples were cut from archived ice at the desert research institute, reno, nevada, by using a bandsaw and transferred to sterile nalgene bottles. these samples comprise surface areas mainly between 15 and 20 cm2, greater than the area sampled in previous studies (e.g., coulter et al. 2012); coupled with the high-latitude, high-elevation locations of the coring sites, they present only a small opportunity to capture remnants of sparse or fleeting ash clouds. in addition, a sulphur peak at 822 ce in tunu2013 was subsequently resampled with respect to a prominent peak in particulate matter; for this event, fine resolution (sub-annual) samples were collected immediately before, across and after the particle peak, bringing the total number of samples examined to 43. samples were shipped to queen’s university belfast, where they were prepared by centrifuging the meltwater to concentrate the particulates, which were then pipetted onto pre-ground glass slides in a laminar flow cupboard and covered in buehler exopycure2 resin. each sample was assigned a unique identifier code (prefixed qub-). slides were scanned at ×100 magnification on a light microscope, and tephra particles were identified with the aid of cross-polarized light. the number of particles >10 µm within each sample was also counted and converted to concentrations to quantify coarse material flux within the ice cores. for samples containing tephra, thin sections were prepared by grinding and polishing the slides until the surfaces of tephra shards were freshly exposed. major element geochemical composition of the glass shards was determined by using integrated electron and wavelength dispersive spectrometry on a jeol fegsem 6500f at queen’s university belfast following coulter et al. (2012). secondary glass standards were analysed at the start and end of each session and between samples to evaluate analytical precision. all data were normalized to facilitate comparison with published data, and are reported, along with secondary glass standard data, in the supplementary data set. results figure 2 shows the positions of the tephra samples relative to the available sulphur and particle concentrations in the neem-2011-s1 and tunu2013 ice cores. the extended period of heightened sulphur volcanism evident in the neem-2011-s1 core between 818 and 822 ce (büntgen et al. 2017) is also visible in tunu2013. the tunu2013 record contains greater inter-annual variability, however, potentially owing to (1) the coring site’s closer proximity to iceland, (2) the site’s lower elevation that places it closer to tropospheric sulphur emission sources and (3) the lower snow accumulation rate, which allows for enhanced surface snow mixing. fluctuations in the tunu2013 fine (<10 µm) particle fractions follow neither an annual nor a seasonal pattern. both fractions show close correspondence with each other, with elevated levels at 814, 817, 822, 823, 825 and 830 ce, with smaller peaks at 815, 816, 819, 821, 826, 831 and 832 ce. visual examination of the samples under a light microscope showed the prominent peak at ca. 830 ce (qub-1886) to relate to mineral dust. the smaller peaks at ca. 826 ce (qub-1883), 831 (qub-1888) and 832 ce (qub-1889) also contained mineral dust and variously included occasional examples of charcoal, fungal spores and diatoms. coarse particles (>10 µm) were present in all samples, but their concentrations were an order of magnitude greater in the tunu2013 core (supplementary data set). notable increases in coarse particles occur in the neem-2011-s1 core at 828–9 (qub-1847) and 835–6 ce (qub-1853), and in tunu2013 at 814 (qub-1870) and 826–7 ce (qub-1883); only the last-mentioned peak coincides with elevated sulphur levels. qub-1878, dating to 821–2 ce, contained a large number of poorly preserved sponge spicules and diatoms, as did the overlapping sample qub-1974; the presence of such material implies the transport of marine water to the sampling site. fig. 2  positions of tephra samples from the neem-2011-s1 and tunu2013 ice cores in relation to their respective non-sea salt sulphur (nsss) records, and the insoluble particle record from tunu2013. t or t? indicates the presence of tephra or possible tephra. examples of non-tephra particles are shown below (qub-1881: charcoal and diatom; qub-1886: charcoal and fine dust; qub-1878: fine dust, biogenic silica). only five of the 43 quasi-annual samples yielded unambiguous tephra particles, ranging from one to five shards per sample (supplementary data set; supplementary figs. s1–s6); in some of these, additional potential shards were present but were too small to enable certain identifications. a probable glass shard was recorded in one other sample (qub-1841; supplementary fig. s2), but its diminutive size prohibited geochemical analysis. although it is now possible on certain microprobes to analyse tephra by using a 3-µm focused beam (hayward 2012), it remains a major challenge to expose a large enough surface area of glass in thin section without destabilizing the resin or polishing away the shard, especially if shards have a platey (i.e., thin) morphology. possible tephra shards were also present in qub-1870, but none of the analysed targets proved to be glass; this sample also contained the highest concentration of coarse particles in all of the ice examined in this study. as a test of the reliability of the analytical data obtained from the very sparse shards and to ensure that results were not skewed by the presence of mineral inclusions, multiple analyses from each shard were obtained where particle size permitted. analytical totals frequently fell below the normally accepted threshold of 95 wt% proposed by hunt & hill (1993), albeit above ca. 90 wt% deemed acceptable by froggatt (1992). we have found this to be a frequent challenge when working with small particles as epoxy resin is entrapped during analysis, demonstrated by elevated cl (coulter et al. 2012). in some instances reported here, we attribute low totals at least in part to instrumental settings, noting lower than usual totals for the secondary glass standards at the time of analysis (see supplementary data set). qub-1835, 815 ce a single bubble-walled shard of colourless glass in neem-2011-s1 yielded three analyses, but the composition of the initial analysis is not replicated by the subsequent two. geochemical heterogeneity and low analytical totals (<95 wt%) highlight a need for caution in the interpretation of the data. however, the glass showed no physical signs of weathering, and post-analysis examination shows burning beyond the edges of the shard (supplementary fig. s1), which will have contributed to low totals, as well as cl entrapment. all things considered, therefore, we attribute the low totals to problematic analyses rather than hydration. an attempt to characterize the trace element composition of the qub-1835 shard by using laser ablation inductively coupled plasma mass spectrometry proved unsuccessful because of the return of a low signal, reflecting the limited glass available for analysis. in neem-2011-s1 at this time, sulphur remains at background levels. in our database, the major element composition of the first analysis most closely matches that of lipari, italy (supplementary fig. s7), the monte pilato eruptive event of which has been dated to 776 +100/−90 ce (keller, cited by lucchi et al. 2007) and is therefore within the same timeframe. the subsequent analyses are not, however, consistent with this source but are instead similar to some material from the south mono eruption of mono craters, california, dated to 594–648 ce (bursik et al. 2014). interestingly, bursik et al. (2014) have posited a remobilization event following a fire ca. 200 years after the south mono eruption. however, we observe no obvious increases in either coarse particle content or charcoal that might suggest a dust deposition event, particularly one associated with a fire. no tephra was identified in the corresponding levels in tunu2013. all in all, given the questionable quality of the data, it is not possible to propose correlatives for this tephra, and further sampling of ice of this age is warranted. the geochemical heterogeneity of the shard is possibly indicative of secondary deposition of weathered glass, but in view of the shard size (>40 µm), the absence of visible signs of weathering and the lack of other material in the sample that would point to a dust event (e.g., charcoal, pollen, coarse-grained minerals), we conclude that qub-1835 is likely to be the result of primary airfall. qub-1872, 816 ce three analyses were obtained from a colourless, platey shard in tunu2013. the shard is characterized by a very distinctive high sio2 and very low feototal and cao content. analytical totals were consistently low, but the data indicate a homogenous chemistry across the shard. we have been unable to identify a possible source for this tephra, but similar tephras of pliocene to pleistocene age have been reported from marine cores from the north-western pacific (cao et al. 1995), suggesting a potential derivation from the kamchatkan/kurile region. four additional tephra-like particles measuring ca. 10–20 µm were present but were too small to analyse on our instrument. a range of similarly sized minerals, including feldspars, were present but not notably abundant. the tunu2013 sulphur and particle records are slightly elevated in early 816 ce. the potential source region (i.e., upwind of greenland) for the analysed shard increases the likelihood that this material could be reworked, yet the homogeneous glass geochemistry and the simultaneous increase, albeit modest, in sulphur are consistent with primary deposition following an eruption. qub-1873, 817 ce a single shard of brown, cuspate glass produced three consistent analyses that indicate a trachydacitic composition. no certain correlatives were identified for this tephra, but the chemistry is similar to the ca. 80-ky-old neem2049.3 identified in greenland ice and attributed to the eastern aleutian arc (bourne et al. 2016; supplementary fig. s8). it also bears some similarities to trachydactic glass from shiveluch (ponomareva et al. 2015; ponomareva et al. 2017), although such glass has not been reported from this time interval. some smaller glass particles (<20 µm) were also noted, and other large particles were present in below-average concentrations. the sample’s position in tunu2013 coincides with small peaks in sulphur and fine particles in early 817 ce. on the basis of the consistent analyses and association with volcanogenic sulphur, we propose that this particle is from primary ashfall. qub-1974, 822 ce only one analysis was feasible on the isolated light brown, cuspate shard recorded in this tunu2013 sample. despite a low analytical total, the distinctive geochemistry can reliably be attributed to katla, iceland (supplementary fig. s9). this sample is directly associated with major fine particle and sulphur peaks in early 822 ce, but coarse particles were not notably abundant in this or the overlapping sample qub-1878. in view of the shard’s unambiguous geochemistry and its direct association with a significant sulphur peak, we conclude that the shard is undoubtedly from primary ashfall. qub-1880, 824 ce of the four certain glass shards identified in this tunu2013 sample, analyses were obtained from three. all three shards are rhyolitic and characterized by low cao (<0.9 wt%) and high k2o (>4 wt%). one shard yielded three slightly dissimilar analyses, all comparatively enriched with al2o3, feototal and tio2, pointing to the entrapment of a large mineral inclusion that is visible within the glass (supplementary fig. s6a). the remaining two shards show a strong correlation with material identified by nooren et al. (2009) and nooren et al. (2017) amongst el chichón samples in delta deposits to the north of this volcano in mexico. although nooren et al. (2009: 109) describe their unit e shards as sharp-edged, the geochemical similarity of this material with 84-ky-old los chicoyos tephra from atitlán, guatemala, led post (2016) and nooren et al. (2017) to conclude that this component represents older, reworked tephra rather than primary ashfall. a similar cryptotephra has been reported in sparse quantities from european terrestrial sediments dating to ca. 650 ce and 400 ce (plunkett & pilcher 2018: dom-3 and dom-4 group 1) and neem-2011-s1 ice dating to 536 ce (sigl et al. 2015: qub-1859 shards 1, 10 and 11). contrary to loveluck et al. (2018), this material is very distinct from icelandic tephra and bears no geochemical similarity to the shards reported from the colle gnifetti ice core from switzerland. the geochemical homogeneity of the distal correlatives leads us to question the attribution to a pleistocene eruption of atitlán, if indeed the cryptotephras are from the same source, as we would expect greater evidence for weathering from an 84-ky-old deposit. furthermore, it seems unlikely that remobilized sediment from a tropical environment would be transported to northern europe and greenland. considering the frequency of a similar tephra in mexican sediments, a source within this broader region seems likely. the sample partly captures a minor particle peak in mid-823 ce, but coarse particle concentrations are below average for this ice core section. despite a lack of association with sulphur, the shards comprise sharp glass and, with the exception of the example containing a mineral inclusion, have yielded consistent analyses. we argue, therefore, that they derive from a primary ashfall of unknown origin, but possibly emanating in southern north/central america. discussion our study of two continuous ca. 20-year sections of greenland ice reveals that the tephra presence in late holocene ice is not constant. although the low flux of optically identifiable volcanic particles reaching the ice cores may imply that isolating tephra in these records is rather haphazard, a correspondence between observed glass shards and elevated fine particle content demonstrates that these sparse occurrences are associated with pulses of non-seasonal dust reaching the ice. in contrast, coarse minerals in all of our samples demonstrate that particles in the size range of the tephra shards we report are regularly transported to greenland, especially to the north-eastern site of tunu, but they are not palpably correlated with elevated sulphur or tephra (supplementary fig. s11). we can conclude that although large particles are persistently present in the ice cores, tephra shards are not, nor are the shards associated with elevated levels of coarse material. we infer that the sparse tephras we record are unlikely to be indicative of dust storm events. of the five cryptotephra samples described here, we can identify with certainty the provenance of only one. fortuitously, the unique geochemical composition of katla basaltic tephra enables us to attribute qub-1974 with high confidence to this volcano. büntgen et al. (2017) demonstrated that a katla eruption triggered a glacial outburst that is dated by dendrochronology to 822/3 ce and proposed that this event was responsible for a sulphate anomaly in greenland ice cores at this time. our tephra shard, coinciding precisely with the 822 ce sulphate and particle peaks in tunu2013, unequivocally corroborates this correlation, and we conclude that this solitary particle represents primary ashfall. the coeval deposition of sulphur and glass implies simultaneous transport by tropospheric or stratospheric winds, rather than the subsequent remobilization of glacial flood deposits as described by prospero et al. (2012). qub-1835 has produced heterogeneous results from a single shard, preventing firm attribution to any specific source. the disparity may signify glass alteration, and there is no associated rise in volcanogenic sulphur to signify a coeval eruption. the absence of a sulphur peak in the ice does not, however, exclude the possibility that the material derives from primary ashfall: öraefajökull 1362 ce tephra was recorded in high concentration in the grip core in the ice of the same age but was not accompanied by a sulphate layer (coulter et al. 2012). perhaps more telling is the absence of similarly sized dust particles and other terrestrial content that one might expect to be remobilized with reworked tephra. the remaining three samples in this study are more robust in their geochemical characterization but nevertheless pose conundrums in terms of understanding their derivation. qub-1872 and qub-1873 both possibly originate from the north pacific region but neither clearly corresponds with a known late holocene tephra. in both instances, the potential source region lies upwind of greenland, and it is conceivable that the shards represent reworked material, the geochemistry of which might have been altered through weathering. however, the coincidence of elevated sulphur and the absence of increases in other coarse particles strengthens the likelihood that the shards derive from unidentified eruptions. qub-1880 comprises a larger number of shards whose origins are less clear; that the major element geochemical composition was reproducible from two shards suggests that the glass geochemistry is unaltered. we find that material with matching major element geochemistry was deposited in greenland and continental europe on multiple occasions in the centuries preceding 824 ce, although the concentrations of tephra associated with these events are generally very low. we note a possible correlative also with an outlying population reported amongst el chichón tephra in mexico, implying a possible origin in southern north america or central america, an improbable source region of remobilized dust that could reach northern greenland and europe. we propose, therefore, that the multiple incidents of this glass type represent primary ashfall. despite the difficulties in determining the source of all but one of the glass shards we have analysed, we conclude—with varying degrees of confidence—that the material represents primary deposition. we find no certain evidence of physical or chemical alteration of glass, and the samples containing confirmed tephra are not associated with increases in similarly sized terrestrial particles that we might expect had sediment been remobilized in dust storms. conclusion we have examined the occurrence of tephra in two greenland ice cores spanning a period of about 20 years, and their relationship to volcanogenic sulphur, fine (2.5–9.5 µm) and coarse (> 10 µm) particulate matter. like previous studies (abbott & davies 2012; coulter et al. 2012), we find that not all sulphur peaks are associated with tephra; this may be because of eruptions that produced little or no ash, or ash clouds not reaching the ice core localities due to meteorological conditions or the distance of the eruption from the polar region. equally, tephras are not always associated with sulphur peaks, highlighting that not all volcanic eruptions emit aerosols in concentrations to impact climate. tephra was present in six (possibly seven) of our 43 samples in low concentrations, despite the relatively sizeable samples examined in this study. these findings demonstrate that tephra occurrence in the ice cores is not rare, but nor is it consistently present as a background input as similarly coarse particulates appear to be. specifically, tephra seems to occur in association with episodic pulses of particulate matter, often with elevated sulphur levels. the association of a solitary tephra shard of katla origin with a sulphur layer contemporary with the 822 ce eruption of that same volcano in nearby iceland serves to emphasize the potential significance of even a single shard in the ice cores, providing its geochemical composition is reliably distinct and replicable. affirming previous work (jensen et al. 2014; sun et al. 2014; mcconnell et al. 2017; dunbar et al. 2019), our study demonstrates that exactly co-registered measurements of distinctive volcanic aerosols (e.g., sulphur) and fine particle size distribution in combination with exceptionally good age control of polar ice cores remain the best diagnostic tracer for the presence of tephra within the ice-core strata. at least two of the tephras we have recorded may have an origin in the north pacific region, essentially upwind of greenland given the dominant westerlies. although only single shards were analysed for each of these samples, in neither instance do we find evidence that the shards are weathered. their association with slightly elevated sulphur levels favours their interpretation as primary deposits from as yet unidentified eruptions. the sample that yielded the largest number of analysable shards finds its closest geochemical match with recurrent tephras reported in both mexico and mainland europe; we argue that the geochemical homogeneity shown by these tephras implies unweathered, primary ashfall, and that the source likely lies in the region around mexico. it follows that low shard concentration should not negate the potential significance of tephra in the polar ice cores; unless there are unambiguous signs of physical or chemical weathering or exceptional levels of coarse terrestrial matter, a single shard can aid the identification of the source volcanic eruption. nevertheless, sparse concentrations of tephra present major challenges in terms of ensuring robust geochemical characterization and the differentiation of potentially altered glass. where possible, we have obtained multiple analyses on individual grains to gauge the reliability of the geochemical signature and to assess the possibility of glass hydration. we advocate the quantification of tephra-sized particles within ice core samples as a means of evaluating the likelihood of remobilized sediment deposition at the ice core localities. in the absence of firm evidence for the presence of reworked tephra, and considering the exceptional weather conditions needed to transport remobilized material to high-altitude polar locations, we propose that tephras encountered in greenland ice cores potentially relate to primary ash fall, irrespective of low shard concentrations. acknowledgements we thank the many persons involved in logistics, drill developments and drilling, and ice-core processing and analysis in the field and in our laboratories. we thank monica arienzo, daniel pasteris, larry layman, rachael rhodes and olivia maselli for laboratory assistance. we are very grateful to beth “bella” bergeron for her valuable expertise and hard work drilling the tunu2013 cores. our field team received valuable assistance from chm2 hill companies ltd. and ken borek air. the neem project is directed by the centre for ice and climate at the niels bohr institute, copenhagen, and the us national science foundation office of polar programs. trace element analysis was conducted on qub-1835 with the assistance of nick pearce, aberystwyth university. we are grateful to two anonymous reviewers whose constructive comments have helped to improve the manuscript. references abbott p.m. & davies s.m. 2012. volcanism and the greenland ice-cores: the tephra record. earth-science reviews 115, 173–191, doi: 10.1016/j.earscirev.2012.09.001. barbante c., kehrwald n.m., marianelli p., vinther b.m., steffensen j.p., cozzi g., hammer c.u., clausen h.b. & siggaard-andersen m.l. 2013. greenland ice core evidence of the 79 ad vesuvius eruption. climate of the past 9, 1221–1232, doi: 10.5194/cp-9-1221-2013. bory a.m., biscaye p.e., piotrowski a.m. & steffensen j.p. 2003. regional variability of ice core dust composition and provenance in greenland. geochemistry, geophysics, geosystems 4, article no. 1107, doi: 10.1029/2003gc000627. bory a.m., biscaye p.e., svensson a. & grousset f.e. 2002. seasonal variability in the origin of recent atmospheric mineral dust at northgrip, greenland. earth and planetary science letters 196, 123–134, doi: 10.1016/s0012-821x(01)00609-4. bourne a.j., abbott p.m., albert p.g., cook e., pearce n.j., ponomareva v., svensson a. & davies s.m. 2016. underestimated risks of recurrent long-range ash dispersal from northern pacific arc volcanoes. scientific reports 6, article no. 29837, doi: 10.1038/srep29837. büntgen u., eggertsson ó., wacker l., sigl m., ljungqvist f.c., di cosmo n., plunkett g., krusic p.j., newfield t.p., esper j., lane c., reinig f. & oppenheimer c. 2017. multi-proxy dating of iceland’s major pre-settlement katla eruption to 822–823 ce. geology 45, 783–786, doi: 10.1130/g39269.1. büntgen u., myglan v.s., charpentier ljungqvist f., mccormick m., di cosmo n., sigl m., jungclaus j., wagner s., krusic p.j., esper j., kaplan j.o., de vaan m.a.c., luterbacher j., wacker l., tegel w. & kirdyanov a.v. 2016. cooling and societal change during the late antique little ice age from 536 to around 660 ad. nature geoscience 9, 231–236, doi: 10.1038/ngeo2652. bursik m., sieh k. & meltzner a. 2014. deposits of the most recent eruption in the southern mono craters, california: description, interpretation and implications for regional marker tephras. journal of volcanology and geothermal research 275, 114–131, doi: 10.1016/j.jvolgeores.2014.02.015. cao l.q., arculus r.j. & mckelvey b.c. 1995. geochemistry and petrology of volcanic ashes recovered from sites 881 through 884: a temporal record of kamchatka and kurile volcanism. proceedings of the ocean drilling program, scientific results 145, 345–381. coulter s.e., pilcher j.r., plunkett g., baillie m.g.l., hall v.a., steffensen j.p., vinther b.m., clausen h.b. & johnsen s.j. 2012. holocene tephras highlight complexity of volcanic signals in greenland ice cores. journal of geophysical research—atmospheres 117, d21303, doi: 10.1029/2012jd017698. dunbar n.w., iverson n.a., van eaton a.r., sigl m., alloway b.v., kurbatov a.v., mastin l.g., mcconnell j.r. & wilson c.j.n. 2017. new zealand supereruption provides time marker for the last glacial maximum in antarctica. scientific reports 7, article no. 12238, doi: 10.1038/s41598-017-11758-0. esper j., schneider l., krusic p.j., luterbacher j., büntgen u., timonen m., sirocko f. & zorita e. 2013. european summer temperature response to annually dated volcanic eruptions over the past nine centuries. bulletin of volcanology 75, article no. 736, doi: 10.1007/s00445-013-0736-z. flanner m.g., gardner a.s., eckhardt s., stohl a. & perket j. 2014. aerosol radiative forcing from the 2010 eyjafjallajökull volcanic eruptions. journal of geophysical research—atmospheres 119, 9481–9491, doi: 10.1002/2014jd021977. froggatt p.c. 1992. standardization of the chemical analysis of tephra deposits. report of the icct working group. quaternary international 13, 93–96, doi: 10.1016/1040-6182(92)90014-s. hadley d., hufford g.l. & simpson j.j. 2004. resuspension of relic volcanic ash and dust from katmai: still an aviation hazard. weather and forecasting 19, 829–840, doi: 10.1175/1520-0434(2004)019<0829:rorvaa>2.0.co;2. hammer c.u., clausen h.b. & dansgaard w. 1980. greenland ice sheet evidence of post-glacial volcanism and its climatic impact. nature 288, 230–235, doi: 10.1038/288230a0. hayward c. 2012. high spatial resolution electron probe microanalysis of tephras and melt inclusions without beam-induced chemical modification. the holocene 22, 119–125, doi: 10.1177/0959683611409777. hildreth w. & fierstein j. 2012. the novarupta-katmai eruption of 1912—largest eruption of the twentieth century: centennial perspectives. professional paper 1791. reston, va: us geological survey. hunt j.b. & hill p.g. 1993. tephra geochemistry: a discussion of some persistent analytical problems. the holocene 3, 271–278, doi: 10.1177/095968369300300310. iverson n.a., kalteyer d., dunbar n.w., kurbatov a. & yates m. 2017. advancements and best practices for analysis and correlation of tephra and cryptotephra in ice. quaternary geochronology 40, 45–55, doi: 10.1016/j.quageo.2016.09.008. jensen b.j.l., pyne-o’donnell s., plunkett g., froese d.g., hughes p.d.m., sigl m., mcconnell j.r., amesbury m.j., blackwell p.g., van den bogaard c., buck c.e., charman d.j., clague j.j., hall v.a., koch j., mackay h., mallon g., mccoll l. & pilcher j.r. 2014. transatlantic distribution of the alaskan white river ash. geology 42, 875–878, doi: 10.1130/g35945.1. loveluck c.p., mccormick m., spaulding n.e., clifford h., handley m.j., hartman l., hoffmann h., korotkikh e.v., kurbatov a.v., more a.f. & sneed s.b. 2018. alpine ice-core evidence for the transformation of the european monetary system, ad 640–670. antiquity 92, 1571–1585, doi: 10.15184/aqy.2018.110. lowe d.j. 2011. tephrochronology and its application: a review. quaternary geochronology 6, 107–153, doi: 10.1016/j.quageo.2010.08.003. lucchi f., tranne c.a., de astis g., keller j., losito r. & morche w. 2008. stratigraphy and significance of brown tuffs on the aeolian islands (southern italy). journal of volcanology and geothermal research 177, 49–70, doi: 10.1016/j.jvolgeores.2007.11.006. lupker m., aciego s.m., bourdon b., schwander j. & stocke, t.f. 2010. isotopic tracing (sr, nd, u and hf) of continental and marine aerosols in an 18th century section of the dye-3 ice core (greenland). earth and planetary science letters 295, 277–286, doi: 10.1016/j.epsl.2010.04.010. maselli o.j., chellman n.j., grieman m., layman l., mcconnell j.r., pasteris d., rhodes r.h., saltzman e. & sigl m. 2017. sea ice and pollution-modulated changes in greenland ice core methanesulfonate and bromine. climate of the past 13, 39–59, doi: 10.5194/cp-13-39-2017. mcconnell j.r., burke a., dunbar n.w., kohler p., thomas j.l., arienzo m.m., chellman n.j., maselli o.j., sigl m., adkins j.f., baggenstos d., burkhart j.f., brook e.j., buizert c., cole-dai j., fudge t.j., knorr g., graf h.f., grieman m.m., iverson n., mcgwire k.c., mulvaney r., paris g., rhodes r.h., saltzman e.s., severinghaus j.p., steffensen j.p., taylor k.c. & winckler g. 2017. synchronous volcanic eruptions and abrupt climate change similar to 17.7 ka plausibly linked by stratospheric ozone depletion. proceedings of the national academy of sciences of the united states of america 114, 10035–10040, doi: 10.1073/pnas.1705595114. miyake f., nagaya k., masuda k. & nakamura t. 2012. a signature of cosmic-ray increase in ad 774–775 from tree rings in japan. nature 486, 240–242, doi: 10.1038/nature11123. nooren c.a.m., hoek w.z., tebbens l.a. & martín del pozzo a.l. 2009. tephrochronological evidence for the late holocene eruption history of el chichón volcano, mexico. geofísica internacional 48, 97–112. nooren k., hoek w.z., van der plicht h., sigl m., van bergen m.j., galop d., torrescano-valle n., islebe g., huizinga a., winkels t. & middelkoop h. 2017. explosive eruption of el chichón volcano (mexico) disrupted 6th century maya civilization and contributed to global cooling. geology 45, 175–178, doi: 10.1130/g38739.1. palais j.m., germani m.s. & zielinski g.a. 1992. inter‐hemispheric transport of volcanic ash from a 1259 ad volcanic eruption to the greenland and antarctic ice sheets. geophysical research letters 19, 801–804, doi: 10.1029/92gl00240. plunkett g. & pilcher j.r. 2018. defining the potential sources region of volcanic ash in northwest europe during the midto late holocene. earth-science reviews 179, 20–37, doi: 10.1016/j.earscirev.2018.02.006. ponomareva v., portnyagin m., pendea i.f., zelenin e., bourgeois j., pinegina t. & kozhurin a. 2017. a full holocene tephrochronology for the kamchatsky peninsula region: applications from kamchatka to north america. quaternary science reviews 168, 101–122, doi: 10.1016/j.quascirev.2017.04.031. ponomareva v., portnyagin m., pevzner m., blaauw m., kyle p. & derkachev a. 2015. tephra from andesitic shiveluch volcano, kamchatka, nw pacific: chronology of explosive eruptions and geochemical fingerprinting of volcanic glass. international journal of earth sciences 104, 1459–1482, doi: 10.1007/s00531-015-1156-4. post j. 2016. reconstructing the eruption history of el chichón volcano from river terraces (chiapas, mexico). master’s thesis, dept. of earth science, university of utrecht. prospero j.m., bullard j.e. & hodgkins r. 2012. high-latitude dust over the north atlantic: inputs from icelandic proglacial dust storms. science 335, 1078–1082, doi: 10.1126/science.1217447. robock a. 2000. volcanic eruptions and climate. reviews of geophysics 38, 191–219, doi: 10.1029/1998rg000054. ruth u., wagenbach d., steffensen j.p. & bigler m. 2003. continuous record of microparticle concentration and size distribution in the central greenland ngrip ice core during the last glacial period. journal of geophysical research—atmospheres 108, article no. 4098, doi: 10.1029/2002jd002376. siebert l., simkin t. & kimberly p. 2011. volcanoes of the world. 3rd edn. berkeley: university of california press. sigl m., mcconnell j.r., layman l., maselli o., mcgwire k., pasteris d., dahl‐jensen d., steffensen j.p., vinther b., edwards r. & mulvaney r. 2013. a new bipolar ice core record of volcanism from wais divide and neem and implications for climate forcing of the last 2000 years. journal of geophysical research—atmospheres 118, 1151–1169, doi: 10.1038/nature14565. sigl m., winstrup m., mcconnell j.r., welten k.c., plunkett g., ludlow f., büntgen u., caffee m., chellman n., dahl-jensen d., fischer h., kipfstuhl s., kostick c., maselli o.j., mekhaldi f., mulvaney r., muscheler r., pasteris d.r., pilcher j.r., salzer m., schüpbach s., steffensen j.p., vinther b.m. & woodruff t.e. 2015. timing and climate forcing of volcanic eruptions for the past 2,500 years. nature 523, 543–549, doi: 10.1038/nature14565. steen‐larsen h.c., masson‐delmotte v., sjolte j., johnsen s.j., vinther b.m., bréon f.m., clausen h.b., dahl‐jensen d., falourd s., fettweis x. & gallée h. 2011. understanding the climatic signal in the water stable isotope records from the neem shallow firn/ice cores in northwest greenland. journal of geophysical research—atmospheres 116, d6, doi: 10.1029/2010jd014311. stoffel m., khodri m., corona c., guillet s., poulain v., bekki s., guiot j., luckman b.h., oppenheimer c., lebas n. & beniston m. 2015. estimates of volcanic-induced cooling in the northern hemisphere over the past 1,500 years. nature geoscience 8, 784–788, doi: 10.1038/ngeo2526. sun c.q., plunkett g., liu j.q., zhao h.l., sigl m., mcconnell j.r., pilcher j.r., vinther b., steffensen j.p. & hall v. 2014. ash from changbaishan millennium eruption recorded in greenland ice: implications for determining the eruption’s timing and impact. geophysical research letters 41, 694–701, doi: 10.1002/2013gl058642. tanaka t.y. & chiba m. 2006. a numerical study of the contributions of dust source regions to the global dust budget. global and planetary change 52, 88–104, doi: 10.1016/j.gloplacha.2006.02.002. toohey m., krüger k., schmidt h., timmreck c., sigl m., stoffel m. & wilson r. 2019. disproportionately strong climate forcing from extratropical explosive volcanic eruptions. nature geoscience 12, 100–107, doi: 10.1038/s41561-018-0286-2. zielinski g.a., dibb j.e., yang q., mayewski p.a., whitlow s., twickler m.s. & germani m.s. 1997. assessment of the record of the 1982 el chichón eruption as preserved in greenland snow. journal of geophysical research—-atmospheres 102, d25, 30031–30045, doi: 10.1029/97jd01574. zielinski g.a., mayewski p.a., meeker l.d., whitlow s., twickler m.s., morrison m., meese d.a., gow a.j. & alley b. 1994. record of volcanism since 7000 b.c. from gisp2 greenland ice core and implications for the volcano–climate system. science 264, 948–952, doi: 10.1126/science.264.5161.948. ohta.indd 247ohta et al. 2003: polar research 22(2), 247–265 pre-devonian crystalline basement rocks exposed along the western and northern parts of the svalbard archipelago are distributed in two north– south trending zones in north-western spitsbergen. the biscayarhalvøya–holtedahlfonna zone (bhz) (gee & hjelle 1966; gee & moody-stuart 1966; gjelsvik 1979; hjelle & lauritzen 1982), which is bounded by the raudfjorden–monacobreen fault in the west and the breibogen fault in the east, is the subject of the present contribution single-grain zircon dating of the metamorphic and granitic rocks from the biscayarhalvøya–holtedahlfonna zone, north-west spitsbergen yoshihide ohta, alexander n. larionov & alexander m. tebenkov the biscayarhalvøya–holtedahlfonna zone (bhz) in north-western spitsbergen is a north–south trending, narrow horst, with crystalline basement rocks exposed under a devonian unconformity. previous k–ar, 40ar/39ar and rb–sr analyses have confi rmed the occurrence of caledonian thermal events, and grenvillian ages have been obtained by conventional zircon u–pb and single-zircon pb evaporation methods. a total of 55 zircon grains from three samples (an augen metagranite, a micaceous schist and a granitic neosome of migmatite) have been analysed by the single-zircon pb evaporation method. the grains with the age range of ca. 950 1100 my (million years) are the major component in all three samples, suggesting tectono-thermal activity in that period. the detrital versus resorption orgin of the rounded shapes of these grains from the granitic neosome is not clear yet. therefore, the ages of the migmatization and of the sedimentary protoliths are not concluded. the youngest presumed detrital grain from the granitic neosome is 1060 my old. the metagranite, cutting the richarddalen unit, yielded grains with an age of ca. 950 mya. a granite dyke with an age range of 955 968 my cuts the biscayarhuken unit in the northern liefdefjorden area. these indicate the sedimentary protoliths of the richarddalen and biscayarhuken units are pre-neoproterozoic. the youngest detrital zircon ages of ca. 940 my indicate neoproterozoic sedimentary protoliths of the solanderfjellet micaceous schists. a signifi cant population of zircon grains with an age range of 1600 1900 my in all three samples suggests a wide exposure of these rocks in the source areas during mesoand neoproterozoic times. several archean ages have also been obtained. the results are generally conformable with those obtained from north-western spitsbergen. y. ohta, norwegian polar institute, c/o iasc, box 5158 majorstua, no-0302 oslo, norway, yoshihide.ohta @npolar.no; a. n. larionov, centre of isotope research, geological institute, sredniy prospect 74, 199106 st. petersburg, russia; a. m. tebenkov, polar marine geological expedition, ul. pobedy 24, lomonosov, 189510 st. petersburg, russia. 248 single-grain zircon dating, north-west spitsbergen (fig. 1). crystalline rocks occur along the north– south trending anticline axis, and are unconformably overlain by latest silurian (?)/devonian sediments (friend & moody-stuart 1972; gee 1972). in the southern bhz, the crystalline rocks consist of psammo-pelitic phyllites, schists, gneisses and migmatites with a distinct marble unit on the top. these rocks are intruded by unfoliated fig. 1. geological map of the biscayarhalvøya–holtedahlfonna zone (bhz), indicating the sample localities (i, ii and iii) and those of the previousely dated samples (numbers 1 19; see table 1). (a) map of biscayarhalvøya, mainly the northern subzone (nbh) of the bhz. (b) map of the southern subzone (sbh) of the bhz, south of liefdefjorden. map (b) is a southward continuation of map (a). names of faults are abbreviated this way: breibogen fault–bf; hannabreen fault–hf; raud fjorden–monacobreen fault–rmf. place names are abbreviated thusly: biscayarfonna–bf; biscayarhuken–bh; bockfjorden–bfj; dovrefjell– dv; erikbreen–ek; fred olsenfjellet–fo; friedrichbreen–fr; hesteskoholmen–hs; lernerøyane–lr; lilljeborgfjellet–lb; liefdefjorden–lfj; monacobreen–mc; rabotdalen–ra; raudfjorden–rfj; richarddalen–ri; rv–richardvatnet; rt–rivieratoppen; rt–ryptind; siktefl ellet–sk; solanderfjellet–so; wulff berget–wf. place names on the small index map are abbreviated thusly: spitsbergen–sp; nordaust landet–ne; north-west spitsbergen migmatite region–nw; ny-friesland– nf. the orange rectangle on the index map indicates the study area, in the north-west spitsbergen migmatite region. 249ohta et al. 2003: polar research 22(2), 247–265 granites. the schists and gneisses of the northern bhz are associated with metagranitic and metamafi c rocks. except for the augen metagranites and retrogressed eclogites which are present in the bhz (gee 1966a), the rocks in the bhz are very similar to those in the north-western spitsbergen basement area, west of the raudfjorden– monacobreen fault (gee & hjelle 1966; hjelle & ohta 1974). this suggests lithological correlation. single-zircon pb evaporation dating studies of the rocks in the north-western basement rocks have recently been presented by balašov et al. (1996b) and ohta et al. (2002). the present article reports the dating results by the single-zircon pb evaporation method on the rocks of the bhz. geological outline the 7 10 km wide bhz extends from the northern coast of biscayarhalvøya, via liefdefjorden, southwards to holtedahlfonna (south of the area shown in fig. 1), over a distance of ca. 100 km. the zone is structurally subdivided into two— the northern (nbh) and the southern (sbh) subzones—by the hannabreen fault, which runs sse–nnw from the northern coast of liefdefjorden to rivieratoppen on the eastern coast of raudfjorden (gee 1966a; gjelsvik 1979). the hannabreen fault displays a hinge fault geometry. in its southern reaches, silurian (?)–devonian rocks in the east are downfaulted. in its northern reaches (north of lilljeborgfjellet), the western side is downfaulted. the nbh subzone was fi rst mapped by gee (1966a) and successively studied by gayer et al. (1966), peucat et al. (1989), dallmeyer et al. (1990), hesbøl (1996), gromet & gee (1998) and ohta & larionov (1998). the sbh was fi rst visited by hoel (1914) and holtedahl (1914a, b). a regional map was presented by gjelsvik (1979). the northern part of the sbh was recently studied by pipjohn & thiedig (1994, 1995, 1997), and wyss et al. (1998) worked in the west of bockfjorden. russian geologists have studied throughout the bhz since the 1960s, but no publication has been issued on the crystalline rocks. the nbh subzone consists of fi ve to six thrust duplex units, which run north–south to nnw– sse and dip moderately and/or steeply eastward. each duplex unit is a few km wide and verging to the west. these units consist of different lithotectonic units (gee 1966a; gee & hjelle 1966; peucat et al. 1989; dallmeyer et al. 1990), which are summarized below in structurally ascending order, from the west to the east (some are repeated). these lithological divisions are hereafter termed “complex” and “units”, since their stratigraphic defi nitions are unclear. place names that formerly began with “biskayer” have been changed to “biscayar-”, in accordance with recent offi cial topographic maps. biscayarfonna complex the richarddalen unit comprises various gneisses, agmatitic diorite, garnet-bearing schists and gneisses, porphyritic meta-granite, small amphibolites with retrograded eclogites and marbles. the montblanc unit is mainly banded schists and gneisses and some amphibolites. the biscayarhuken unit consists of various phyllites with quartzite and a small amount of marbles. the wulff berget and erikbreen areas on the northern coast of liefdefjorden, west of the hannabreen fault (sbh), comprise a 4 km wide zone of east verging thrust duplexes consisting of marbles, with a 0.5 km thick package of phyllite and schists in the middle (ilys et al. 1995; ohta et al. 1995). these marbles extend south across liefdefjorden and form the western limb of a major anticline structure of the sbh. the same marbles occur on the eastern limb. three lithological units—marbles, pelitic schist, gneisses and migmatites—are recognized in the pre-devonian liefdefjorden complex (gjels vik 1979; piepjohn & thiedig 1995; wyss et al. 1998), in the sbh, structurally descending in the following order. the migmatites occupy the crestal part of the regional anticline. both the marbles and pelitic schists and gneisses are involved in a complex thrust duplex of a brittle nature, although the marbles are often ductile, and east verging structures are well developed in both limbs of the anticline (piepjohn & thiedig 1995, 1997; ohta et al. 1995), with thrust surfaces dipping to the east in the eastern limb. the migmatites locally show intrusive contacts to the pelitic gneisses, and the latter are included as randomly rotated angular enclaves in heterogeneous granitic neosomes. the neosomes locally have fl ow structures. a homogeneous granite, similar to the grey granite in north-western spitsbergen, intrudes 250 single-grain zircon dating, north-west spitsbergen the migmatites in the crestal part of the anticline in the eastern fred olsenfjellet and around ryptind, west of bockfjorden (wyss et al. 1998). all varieties of metamorphic and migmatitic rocks described above from the sbh are included in the granite as xenoliths. the axis of the regional anticline plunges gently to the south, so that the top-seated marbles cover the anticline crest and both limbs in the southern most part of the sbh. the three-fold lithotectonic divisions in the nbh and sbh subzones have been correlated with the generalfjella, signehamna and nissenfjella units of north-western spitsbergen (gee & hjelle 1966; hjelle & ohta 1974; hjelle 1979; hjelle & lauritzen 1982; harland 1997). cenozoic volcanic rocks and hot springs are roughly aligned along the breibogen fault, near the western side of bockfjorden. the basaltic rocks contain a large number of ultramafi c, upper mantle enclaves and lower crustal granulitic rocks of grenville age (amundsen et al. 1987; skjelkvåle et al. 1989), and they imply the presence of high grade metamorphic rocks in the abyss and depth of the breibogen fault. previous geochronological studies in the bhz several isotopic dating studies have been carried out on the rocks of the bhz, especially in the nbh, which are characterized by the occurrence of retrogressed eclogites (gee 1966b; ohta et al. 1989; hesbøl 1996). the results are summarized in table 1. the k–ar, 40ar/39ar, rb–sr, u–pb sphene and single-zircon pb/pb methods have yielded caledonian ages. late caledonian ages of ca. 435 400 my (million years) have been obtained from all lithotectonic units of the bhz (gayer et al. 1966; dallmeyer et al. 1990), while early caledonian ages of 480 my (muscovite from augen granite; dallmeyer et al. 1990), 465 my (biotite from corona gabbro; dallmeyer et al. 1990) and ca. 455 my (u–pb sphene age; gromet & gee 1998) were obtained only from rocks of the richard dalen unit. the last age has been argued to date the eclogite facies metamorphism in the nbh by gromet & gee (1998), while dallmeyer et al. (1990) argued that the high p metamorphism was 504 552 my old based on 40ar/39ar hornblende age. several k–ar hornblende and clinopyroxene ages of 500 1939 my (gayer et al. 1966) and 40ar/39ar ages of 505 550 my of hornblende (dallmeyer et al 1990), obtained from the retrograded eclogites and gneissose amphibolites, have been diffi cult to explain. zircon u–pb ages of ca. 620 660 my have been obtained from the rocks of the richarddalen unit by peucat et al. (1989) and gromet & gee (1998), and interpreted as the igneous protolith age of the retrogressed eclogitic rocks. meta-granite and corona gabbro in the richarddalen unit were dated by conventional u– pb and single-zircon methods and yielded ages of 955 965 my (peucat et al. 1989; gromet & gee 1998). similar ages were obtained from the zircon xenocrysts from devonian tuffi tes (hellman et al. 1998) and from the granulite xenoliths within cenozoic volcanic rocks (amundsen et al. 1987), both in the sbh. a granitic dyke with the single-zircon age of 961 my cuts the phyllites of the biscayarhuken unit on the northern coast of liefdefjorden, and thus sets the youngest limit of the sedimentary protolith of the unit (ohta & larionov 1998). the 950 my old metagranite cuts the gneissosity of the richarddalen unit and contain enclaves of folded marbles from the unit (peucat et al. 1989), demonstrating that the sedimentary protoliths of the unit are also pre-neoproterozoic. zircon xenocrysts from devonian tuffi tes yielded two mesoproterozoic age groups: 1353 1370 my and 1509 1586 my, while a late palaeoproterozoic age of ca. 1737 my was obtained from the quartz porphyry clasts of the lilljeborgfjellet conglomerate, the basal conglomerate of the siktefjellet group (latest silurian ?) (hellman et al. 1998). the presence of inherited archean zircon, ca. 3.2 gy old, within the 950 my old metagranite has been suggested by the concordia upper intercept age (peucat et al. 1989). analytical method zircon grains were analysed by the pb evaporation method, following kober (1986, 1987). each zircon grain was mounted in a canoe-shaped rhenium (re) fi lament and its pb isotope composition analysed in a finnigan mat 261 mass spectrometer at the laboratory for isotope geology of the natural history museum in stockholm. zircon (zrsio4) is decomposed by heating into zro2 (baddeleyite) and sio2; this decomposition front moves from the surface of the grain inwards. to avoid the infl uence of lead as a con251ohta et al. 2003: polar research 22(2), 247–265 taminant on surfaces, in cracks and in metamict domains, the grain is pre-heated from 1350 to 1500 °c, whereas the lead content from unaltered inner domains is evaporated in several steps from 1550 to 1600 °c. the evaporated lead is precipitated on an ionization fi lament at the opposite side of the re fi lament, together with silica. each heating step takes 3 10 min to get an adequate quantity of lead for the isotope analysis. after each analysis, the heating is repeated, with a temperature increment of 10 30 °c, if required. the lead isotope composition of each step is anatable 1. previous isotopic ages from the biscayarhalvøya–holtedahlfonna zone. ages in my (million years). see fig. 1 for the locations of the sites listed by number in the fi rst column. numbers 1 and 2 are in the biscayarhuken unit, 3 8 from the montblanc unit, 9 15 from the richarddalen unit and 18 and 19 are devonian volcanics. no. rock single zircon zircon u–pb sphene u–pb hb 40/39ar ms 40/39ar rock ms rb/sr rock bt rb-sr hb k–ar micas k–ar 1 phyllite 439 ± 20 a 2 granite 955 ± 4 -968 ± 9 h 3 mica schist 230.2 ± 2.8 f 4 amphi-bolite 506.1 ± 2.1 e 389 ± 12 a 5 grt-hb schist 4414.3 e 6 mica schist 442.1 ± 2.3 e 538.5 ± 2.4 e 430.7 ± 0.9 e 428 ± 11 e 402 ± 8 e 413 ± 8 e 7 hb schist 439.3 ± 2.8 e 8 grt-hb gneiss 647 ± 4 667 ± 4 f 425.1 ± 15 458.3 ± 2.4 f 538.2 ± 2.4 e 428 ± 17 b 436 ± 17 b 9 grt amphi -bolite 552.6 ± 2.7 e 454.9 ± 0.7 e 10 retro. eclogite north 653 ± 9 f 655 ± 10 f 620 + 2, –5 e 431.3 ± 4.4 483.4 ± 3.5 f 504.7 ± 2.5 e 443.3 ± 6 e 430 ± 9 e 397 ± 10 550 ± 24 a 780 ± 50 a 1939 ± 12 a 399 ± 5 a 11 retro. eclogite south 529.4 ± 1.7 e 529 ± 15 a 12 meta-granite 3234 ± 43 d 965 ± 1d 480.4 ± 0.6 e 420 ± 10 e 410 ± 8 e 13 agmatitic diorite 661 ± 2 d 423 ± 11 e 14 pegmatite 418 e 433 ± 22 a 15 corona gabbro 955 ± 1 d 465 ± 9 e 16 quartz porphyry 1735 ± 4 1739 ± 5 g 17 tuff 439 ± 6 g 932 ± 15 952 ± 18 g > 1353 ± 7 1370 ± 7 g 1509 ± 45 g > 1586 ± 18 g 18 granulite enclave ca. 980 b basalt ca. 3.0c 19 schist/ gneiss ca. 365 a a data from gayer et al. 1966. d data from peucat et al. 1989. g data from hellman 1998. b data fromamundsen et al. 1987. e data from dallmeyer et al. 1990. h data from ohta & larionov 1998. c data fromskjelkvåle et al. 1989. f data from gromet & gee 1998. 252 single-grain zircon dating, north-west spitsbergen lysed in peak-jumping mode, using the electron multiplier. the measured isotope ratios are corrected for common pb using the obtained 206pb/ 204pb ratio and following the model of stacey & kramers (1975). no correction for fractionation was made. pb evaporation age is calculated from the corrected 207pb/206pb ratio for each block of 10 scans, and the average age for each heating step is computed. if several steps (minimum 2 steps) have a similar age, a weighted average 207pb/206pb age (plateau age) is calculated for these steps using ludwig’s (1991) isoplot program. this age is taken to indicate the age of crystallization of the zircon. the initial steps may often show a deviating lower age, as lead is fi rst released from outer parts that may bear younger overgrowth or from metamict parts of the zircon crystal that may have undergone pb loss or may be enriched in common pb. some zircon grains may show a steady increase in age to the fi nal step, indicating the presence of older cores. only a minimum age for the crystallization of the zircon core is available in such cases. samples, dating results and comparisons with previous data zircon grains were picked from two samples from the nbh and one from the sbh for dating. two samples from the nbh are from the same localities as those described in dallmeyer et al. (1990a) and peucat et al. (1989), and one sample from the sbh has been collected from the area where the sample of gayer et al. (1966) was taken (fig. 1, table 1). metagranite of the richarddalen unit from south-west biscayarfonna, nbh a gneissose, porphyritic granite occurs at the south-western corner of biscayarfonna, forming a north–south trending 200 m wide zone. it extends discontinuously to sse for ca. 6 km to the north-west of rabotdalen (fig. 1). the metagranite contains k-feldspar augen, up to several centimetres long, and several modal percentages of garnet. in the rabotdalen area, the metagranite displays a massive porphyritic texture. this metagranite includes enclaves of tightly folded marbles and gneisses of the richarddalen unit, and appears as augen gneiss and mylonites, while a vein of fi ne-grained, corona gabbro cuts the gneissosity of metegranite. the contacts with the coarse-grained, garnet-biotite and hornblendebiotite gneisses of the richarddalen unit to the east is concordant, but sheared. these fi eld relations suggest a syntectonic emplacement of primary porphyritic granite and successive metamorphism into augen gneisses and mylonites (peucat et al. 1989). the analysed sample is a high k, s-type adamellite (table 2), containing a signifi cant modal amount of garnet, with biotite and large k-feldspar augen emphasizing its gneissosity. accessories are allanite, apatite, rutil and zircon. the majority of the zircon grains are euhedral in shape, with magmatic zoning, and inclusions are common (fig. 2). however, ca. 10 %, are anhedral grains, with small aspect ratios of 1.5 2.0, rarely 4, and rounded outlines. they are transparent with smooth or rough surfaces and are considered to be inherited grains. cathode luminescence images show core–mantle relations in these grains, indicating different degrees of overgrowth. cores are evidently rounded and discordant to the mantle. nine anhedral zircon grains were selected in order to obtain the protolith age (table 3a, fig. 2). these are rounded with rough or relatively smooth surfaces; some are multi-faceted and have almost spherical outline. grain e (dated to 964 ± 4 mya) is subhedral with a pyramidal shape, suggesting overgrowth. all analysed grains were transparent, pink or yellow in colour, and grain h (dated to > 2539 mya) shows a defi nite core. the rounded xeno crystic shapes of the dated zircon grains are interpreted to result from metamorphic resorption and mechanical corrosion, during the conversion from primary porphyritic granite to garnet-bearing augen gneiss and mylonite. the foliation of the augen gneisses and mylonites are cut by the corona gabbro which yielded an u–pb zircon age of ca. 955 my (peucat et al. 1989). five grains from the metagranite (grains e, f, i, j and k) yielded plateau ages between 937 ± 14 and 976 ± 5 my, with an average of 960 ± 17 my. these ages are consistent with the conventional u–pb age (965 ± 1 my) of peucat et al. (1989), which was interpreted as a magmatic age. these ages are comparable to the single-grain zircon ages of the hesteskoholmen granite sheets (bulk composition in table 2), which have an average age of ca. 961 my (table 1), intruding into the biscayarhuken unit (ohta & larionov 1998). 253ohta et al. 2003: polar research 22(2), 247–265 fig. 2. age evaporation step results. also shown, cathode luminescence images of two grains (not those analysed) from the metagranite of the richarddalen unit (locality i, see fig. 1). table 2. bulk rock compositions of the samples from which analysed zircon grains were picked. sio2 tio2 al2o3 feo* mno mgo cao na2o k2o p2o5 ig loss total 1 a 73.92 0.13 13.11 0.62 0.03 0.29 1.45 2.84 6.54 nd 1.34 100.14 2 b 74.18 0.29 12.33 2.46 0.04 0.38 1.24 4.89 2.33 0.07 1.54 99.46 3 c 65.97 0.83 15.55 6.09 0.09 1.69 1.69 2.76 3.44 0.10 1.50 98.88 a metagranite of the richarddalen unit, south-western biscayarfonna. c granitic neosome from the west of bockfjorden. b granite dyke cutting the biscayarhuken unit on the southern island of hesteskoholmen, northern liefdefjorden (ohta & larionov 1998). 254 single-grain zircon dating, north-west spitsbergen grain d shows somewhat higher minimum age of > 981 ± 13 my, possibly due to inherited old core. two grains, b and g, yielded ages of > 1299 ± 26 my and 1126 ± 13 my, respectively, sug gesting the existence of older core. grain h started from ca. 950 my and fi nally showed a minimum age of > 2539 ± 21 my. this suggests an archean inherited core in the grain, consistent with the upper intercept u–pb age (multi-grain, 3234 ± 43 my; peucat et al. 1989; table 1). no caledonian age has been recorded in the u–pb isotope system of these zircon grains. the inherited ages are widespread and they may point to detrital zircon grains from incorporated sediments. table 3. 207pb/206pb single-zircon dating results from the biscayarhalvøya–holtedahlfonna zone (bhz). table continues opposite page. grain (number of steps on plateau in parentheses) measured age ± 2σ 207pb/206pb ± 2σ % 206pb/204pb ± 2σ % (my) 3a. metagranite of the richarddalen unit, south-western biscayarfonna (locality i in fig. 1) b. euhedral, round corners, brown, transparent (2) 0.085029 1.23 25697 69.60 > 1299 26 d. subhedral, rounded, pink, transparent 0.072141 0.95 63839 119.8 > 981 13 e. subhedral, pink, transparent (6) 0.071627 0.48 66904 40.45 964 4 f. anhedral, fl at, round, pink, transparent, inclusion (5) 0.071725 0.60 41414 32.59 965 5 g. multifaceted, subhedral, pink, transparent (3) 0.076735 2.36 72897 35.05 1126 13 h. anhedral, rounded, pink, transparent 0.169920 0.67 27302 101.1 > 2539 21 i. subhedral, rounded, resorbed, pink, transparent (3) 0.070646 2.58 14449 32.41 937 14 j. multifaceted, subhedral, pink, transparent (3) 0.072035 0.59 39355 60.76 976 5 k. anhedral, rounded, pink, semi-transparent (4) 0.072451 0.99 10264 79.06 957 6 3b. micaceous schists from south-east solanderfjellet, northern subzone (nbh) of the bhz (locality ii in fig. 1) a. moderately rounded, brown, transparent (2) 0.099698 1.95 7075 19.01 1610 8 b. slightly rounded, zoned, pink, transparent (2) 0.071206 0.21 40340 15.35 949 6 c. well-rounded, fl at, pink, transparent (5) 0.108869 0.22 220958 31.02 1779 2 d. well-rounded, fl at, pink, transparent (3) 0.112487 3.56 15015 71.98 1855 10 e. well-rounded, brown, transparent 0.117927 3.75 4066 20.89 > 1888 46 f. prism, slightly rounded, pink, transparent(3) 0.070797 0.20 60718 22.79 938 4 g. rounded, fractured, pink (5) 0.083796 0.23 72232 20.91 1294 3 h. slightly abraded, prismatic, pink, transparent (2) 0.070990 0.14 76247 11.85 952 2 i. well-rounded, fl at, brown (2) 0.075994 0.41 30467 27.39 1080 7 j. rounded, pink, transparent (2) 0.090543 1.02 29015 90.53 1416 7 k. broken, slightly rounded, pink, transparent 0.077730 0.84 21858 46.91 > 1120 15 l. slightly rounded, elongated, pink, transparent (5) 0.101077 0.25 95698 61.81 1646 3 m. non-abraded, broken, pink, transparent (2) 0.072189 0.70 85386 54.53 985 8 n. rounded, zoned, brown, semi-transparent (6) 0.070777 0.16 159611 31.36 947 3 o. rounded, pink, transparent (3) 0.074327 0.44 123485 35.42 1047 5 p. rounded, fl at, pink, transparent (2) 0,090454 0.11 244688 18.27 1431 3 q. well-rounded, fl at, pink, transparent (3) 0.119856 0.17 142085 50.35 1950 2 r. well-rounded, pink, transparent, fl at (4) 0.181826 0.12 181660 18.40 2669 2 s. rounded, pink, transparent (4) 0.106407 0.21 122421 25.90 1735 4 t. rounded, pink, transparent (3) 0.112245 0.43 80832 113.1 1834 3 u. rounded, fl at, pink, transparent (4) 0.113497 0.17 115310 26.64 1854 3 v. rounded, fl at, pink, transparent (4) 0.112192 0.15 336383 38.44 1830 3 w. rounded, fl at, fractured, brown, transparent (3) 0.085172 1.71 40194 35.59 1326 4 x. slightly rounded, fl at, pink, transparent (4) 0.101111 0.25 221063 34.53 1642 2 y. non-abraded, multifaceted, pink, transparent (3) 0.103356 0.38 50724 60.80 1677 5 z. well-rounded, pink, semi-transparent (4) 0.113593 0.85 58689 73.41 1858 4 255ohta et al. 2003: polar research 22(2), 247–265 micaceous schists from solanderfjellet, montblanc unit, nbh micaceous schists with a small amount of schistose amphibolite form a lenticular body, 1.5 km wide and 2.5 km long, in solanderfjellet, northwest of richardvatnet (fig. 1). a north-west striking reverse fault zone bounds this body at its north-eastern margin. several small thrust duplex units, each less than 1 m thick, are developed in the reverse fault zone, illustrating westward stacking. the south-western boundary of the schist body is a thrust dipping moderately to north-east, and the north-western border is the vertical hannabreen fault. the richarddalen unit occurs both structurally above and below the schists, which have been assigned to the montblanc unit (gee 1966a, b; gee & hjelle 1966; peucat et al. 1989; dallmeyer et al. 1990). two-mica schists dominate, associated rocks are hornblende-, garnetand epidote-bearing amphibolites. mesoand micro-structures are characterized by a fi neto medium-grained, lepidoblastic texture, and represent a single metamorphic recrystallization. caledonian 40ar/39ar and rb–sr ages have previously been recorded from the mica schist collected from the same locality sampled here. the 40ar/39ar ages are 442.1 ± 2.3 my (hornblende) and 430.7 ± 0.9 my (muscovite), and the rb–sr age is 413 ± 8 my (biotite) ( dallmeyer et al. 1990; table 1). zircon grains were separated from a garnetbearing, two-mica schist, sampled along the north-west coast of richardvatnet, at the southeastern foothill of solanderfjellet. the sample schist displays a well developed cleavage and its metamorphic grade is not higher than lower amphibolite facies, judging from the metamorphic mineral assemblages with garnet, chlorite, muscovite, biotite, epidote and pale green amphibole. all zircon grains from this sample can therefore be considered detrital. analysed zircon grains differ in shape, aspect ratio, degree of abrasion, colour and internal structure, and some are fragmental, which is typical for detrital grains (table 3b, fig. 3). most grains are transparent or semi-transparent and have relatively light colours. less rounded grains could be considered to be derived from their primary sources, while more rounded grains could have experienced several sedimentary cycles, or alternatively, derived from remote sources. cathode luminescence observations revealed a bright, thin, sometimes discontinuous rim. this might be a signature of later metamorphic / hydrother3c. granitic neosomes of migmatite from west of bockfjorden, southern subzone (sbh) of the bhz (locality iii in fig. 1) r. anhedral, abraded, pink, transparent (2) 0.075577 1.71 37605.1 32.40 > 1097 9 w. subhedral, sharp corners, prism reduced, brown, transparent (3) 0.182249 0.45 32371.8 33.70 2683 3 x. subhedral, sharp corners, core, pink, transparent (2) 0.102451 2.42 18348.9 57.47 1685 11 y. anhedral, abraded, fl at, brown, semi-transparent (4) 0.101514 0.46 43378.3 150.73 1636 4 z. subhedral, sharp corners, multifaceted, transparent (3) 0.326849 0.38 33540 70.44 3604 4 a. subhedral, fractured, zoned, brown, translucent (2) 0.072789 0.54 6109.8 9.04 942 8 b. subhedral, long prismatic, zoned, core, brown, translucent (3) 0.071175 0.41 22101.3 12.56 946 6 e. subhedral, zoned, pink, semi-transparent (5) 0.071201 0.25 162928 45.32 959 3 f. subhedral, multifaceted, fl at, pink, transparent (3) 0.194336 0.57 16617.1 14.00 2775 4 g. anhedral, rounded, fl at, smooth, pink, transparent (2) 0.075262 0.70 103591 79.67 1063 16 i. subhedral, multifaceted, fl at, round corners, brown, transparent (3) 0.085516 0.84 26672.8 22.29 1319 14 k. anhedral, fl at, smooth, pink, transparent 0.093320 4.80 125166 140.10 > 1509 17 m. anhedral, rounded corners, pink, semi-transparent 0.105456 1.09 43339.2 31,85 > 1714 15 n. subhedral, zoned, core?, one vertex, dark brown, semi-transparent (2) 0.108443 1.23 36336.1 72.76 > 1793 34 o. subhedral, rounded corners, healed fracture, zoned, light brown, transparent (3) 0.070163 1.81 152570 68,87 947 4 p. subhedral, prismatic, fl at, zoned, pink, transparent (4) 0.070417 1.13 41036.4 54.02 944 6 q. subhedral, rounded, fl at, core, brown, transparent 0.102813 0.87 62610.7 96.78 > 1667 17 t. subhedral, fl at, sharp corners, pink, transparent (2) 0.101500 0.27 121056 86.12 1645 5 u. anhedral, abraded, fi ne zoning, pink, transparent (4) 0.099014 2.61 53461.0 55.75 1636 5 v. subhedral, scratched, broken vertex, brown, semi-transparent (2) 0.106841 1.15 26473.1 97.11 1750 5 256 single-grain zircon dating, north-west spitsbergen mal resorption events. the 26 analysed zircon grains can be grouped into four age groups (fig. 3, table 3b), as follows. (1) seven grains (b, f, h, i, m, n, o) are dated to 938 ± 4 1080 ± 7 mya. (2) four grains (g, j, p, w) are dated to 1294 ± 3 1431 ± 3 mya, and one grain (k) has a minimum age of 1120 ± 15 my. (3) twelve grains (a, c, d, l, q, s, t, u, v, x, y, z) are dated to 1610 ± 8 1950 ± 2 mya, and one grain (e) with a minimum age of 1888 ± 46 my. (4) one grain (r) has an archean age of 2669 ± 2 my. age group 1. three grains (f, k, n) in this age group show ages as young as 740 my in their early evaporation steps. then ages moderately or gently increase with successive evaporation steps. this suggests pb loss probably due to the caledonian imprint around the margins. grain n shows metamict alteration. grains of this age group comprise ca. 24 % of the analysed grains of this sample. this suggests a signifi cant exposure of grenvillian rocks in the source areas of the protoliths. this age group may have two ill-defi ned age clusters: younger than 985 my and older than 1047 my, separated by a 60 my interval. age group 2. the four grains of this age group can be subdivided into two subgroups with ages overlapping roughly within the error ranges in each subgroup. subgroup 2a comprises: grain g, dated to 1294 ± 3 mya; grain w, dated to 1326 ± 4 mya; and possibly grain k, dated to > 1120 mya. grain k is metamictic. subgroup 2b includes: grain j, dated to 1416 ± 7 mya; and grain p, dated to 1431 ± 3 mya. these two age subgroups represent two separate thermal events. except for grain w, all these grains are strongly abraded, implying a lengthy sedimentary history. ages similar to those of subgroup 2a have been reported from the zircon xenocrysts of the devonian tuffi tes, ca. 6.5 km south fig. 3. age evaporation step fi gure and some cathode luminescence images of zircons from the micaceous schist (locality ii; see fig. 1) from solanderfjellet. 257ohta et al. 2003: polar research 22(2), 247–265 of this locality in the north-western part of sbh (fig. 1, table 1; hellman et al. 1998). age group 3. circa 50 % of the grains in the whole population are 1600 1950 my old, though with a wide age range of 340 my, suggesting a wide exposure of the latest palaeoproterozoic crystalline rocks in the source areas. some grains have overlapping ages within the error rages: grain x (1642 ± 2 my) and grain l (1646 ± 3 my); grain v (1830 ± 3 my) and grain t (1834 ± 3 my); and grain u (1854 ± 3 my) and grain z (1858 ± 4 my), probably derived from the same sources. as the zircon grains with ages from 1830 to 1950 my are less abraded and grain y (1677 my) is even non-abraded, their derivation from primary sources is inferred. the rest of the grains are all well rounded, except for grains s (dated to 1735 mya) and d (1855 mya). the age of grain s is similar to the age of the ca. 1740 my old quartz porphyry clasts from the lilljeborgfjellet conglomarate (hellman et al. 1998; table 1). almost all grains in age group 3 show ages as young as ca. 800 my at their early evaporation steps, suggesting later disturbance of the pb isotope system, but caledonian infl uence may be very weak. age group 4. grain r, with the archean age, of 2669 ± 2 my, is very well rounded, suggesting that it could have experienced several depositional episodes. a weak mantle overgrowth in the latest paleoproterozoic is inferred on the basis of the young ages at the earliest evaporation step of this grain. granitic neosome of migmatite from the west of bockfjorden, sbh the eastern limb of the shb major anticline west of bockfjorden consists of marbles, pelitic schists and gneisses and granitic migmatites, in structurally descending order. the heterogeneous granitic neosomes of the migmatites often contain scattered plagioclase porphyroblasts and show local distinct fl ow foliation. they cut agmatitic migmatite and contain a large amount of strongly assimilated enclaves of pelitic schists, gneisses and marbles (fig. 4). a massive homogeneous, leucocratic granite, similar to the grey granite of north-western spitsbergen (balašov et al. 1996b; ohta et al. 2002), cuts all other metamorphic and migmatitic rocks. zircon grains were separated from a heterogeneous granitic neosome, sampled at the mouth of friedrichbreen. this sample is a medium-grained, weakly gneissose rock, containing ovoidal plagioclase centimetre-sized grains which are partly enclosed by deep brown biotite fl akes. both plagioclase and k-feldspar are thickly overgrown by small sericite fl akes, and myrmekite texture developes between them. quartz is interstitial and shows mylonitic bleb shapes. cordierite grains are strongly replaced by fl akes of muscovite and irregular cracks are pinitized. thin needles of sillimanite are included in plagioclase. the rock has an adamellitic composition, with high k, calcalkaline, s-type characteristics (table 2), and plots in the fi eld of iag+cag+ccg of the sio2 vs feo∗/feo∗+mgo diagram of maniar & piccoli (1989). zircon grains from this sample are euhedral to anhedral; some have fragmental appearences and overgrowth (table 3c, fig. 5a). a number of grains have rounded edges and scratched surfaces, which suggests that the zircon population is heterogen. cathode luminescence images reveal complex core structures of the euhedral and subhedral grains (fig. 5a). the sharp edges and smooth surfaces are mostly due to overgrowth. the cores are discordant to the mantle and the boundaries between them are abrupt or diffused, suggesting possible resorption before or in the very beginning of overgrowth. cathode luminescence-darkness of the mantle is due to the u enrichment, which, in turn, could correspond to the mantle growth during a migmatization event (cornell et al. 1998). fig. 4. occurrence of the migmatite at the mouth of friedrichbreen, south-western coast of bockfjorden. the asterisk marks the dated granitic neosome. the shaft of the hammer in the centre of the photograph is 30 cm long. 258 single-grain zircon dating, north-west spitsbergen four age groups are recognized among the 20 analysed zircon grains (fig. 5, table 3c), as follows. (1) six grains (a, b, e, g, o, p), comprising 40 % of the analysed grains, are dated to 942 ± 8 to > 1063 ± 1 mya, and one grain (r) has a minimum age of > 1097 ± 9 my. (2) one grain (i) is dated to 1319 ± 14 mya. (3) five grains (t, u, v, x, y), i.e. 25 % of the analysed grains, are dated to 1636 ± 4 to 1793 ± 34 mya, and four grains (k, m, n, q) have minimum ages from > 1509 to > 1793 mya. (4) three grains (f, w, z) have ages older than ca. 2683 my. evaporations of the beginning steps for the outer parts of grains were usually not measured. however, in some cases 207pb/206pb ratios correspond to 560 850 mya, suggesting partial reset of the u–pb system by later thermal events on the surface of older grains. fig. 5. (a) age-evaporation step results and some cathode luminescence images of zircon grains from the granitic neozome from the west of bockfjorden (locality iii, see fig. 1). rectangles indicate sections enlarged in (b), opposite page. (a) 259ohta et al. 2003: polar research 22(2), 247–265 age group 1. two clusters of ages may be recognized in this age group. cluster 1a includes fi ve grains (a, b, e, o, p) dated to 942 959 mya. cluster 1b includes one grain (g) dated to 1063 mya, and a second grain (r) with a minimum age of 1097 mya. grains a (dated to 942 ± 8 mya), b (946 ± 6 mya) and p (944 ± 6 mya) of the 1a age cluster are subhedral, while two others—e (959 ± 3 mya) and o (947 ± 4 mya)—have rounded edges and pinnacles. all fi ve grains have clear oscillatory zoning and small inclusions of acicular, short prismatic and dot shapes. grain b contains a rounded core, and possible inherited cores are observed in some of the other grains. these ages indicate that the major zircon crystallization from the granitic melt occurred ca. 950 mya. this age range corresponds to the seconddominant age cluster of the solanderfjellet micaceous schist. grain g (1063 my old) of the 1b age cluster has a rounded outline, without overgrowth, suggesting a detrital origin. this is the youngest age of apparently detrital grains. optical microscopy and cathode luminescence observation do not permit the determination of whether the rounded outlines of the ca. 950 my old grains e and o are products of detrital abrasion or magmatic resorption. if grain g is detrital in origin and the grains of the 1a age cluster are metamorphic, the sedimentary protoliths of the gneissic enclaves in the granitic neosome are younger than 1063 my and older than 959 my. no evidence of caledonian zircon growth has been detected in the present study, though a date of ca. 365 mya has been yielded by the k–ar method from a rock collected in the same area as the present sample (gayer et al. 1966; table 1). age group 2. the short, prismatic, fl at grain (i) of this age group has well developed facets, and gave a well defi ned plateau age of 1319 ± 14 my. comparable ages (1353 1370 my) have been reported from the xenocrystic zircons of the tuffi tes interbedding in the devonian sediments (hellman et al. 1998; table 1). age group 3. this age group can be divided into two age clusters, separated by an interval of ca. 40 my. three younger grains—t (dated to 1645 ± 5 mya), u (1636 ± 5 mya) and y (1636 ± 4 mya)—of this age group show a short range of ca. 10 my and the error ranges are almost overlapping. however, grains t and u display prismatic, subhedral outlines, with slightly rounded edges and rough spots on the facets, while grain y is distinctly abraded. the morphology suggests a detrital nature of these grains. grain k (dated to (b) 260 single-grain zircon dating, north-west spitsbergen > 1509 ± 17 mya), with smooth surfaces and sharp edges, may belong to this age cluster of the latest palaeoproterozoic. grains v (dated to 1750 ± 5 mya), x (1685 ± 11 mya) and three minimum ages of m (> 1714 ± 15 mya), n (> 1793 ± 34 mya) and q (>1667 ± 17 mya) are grouped into a late palaeoproterozoic age cluster. grain n could be older. grain q may belong to this age cluster. all grains of this age cluster have subhedral outlines with relatively sharp edges and smooth facets. this suggests the presence of younger overgrowth, which is supported by the low 207pb/206pb ratios in the beginning stages of analyses giving ages as young as ca. 950 mya (fig. 5). age groups 4. three archean ages have been obtained. they show at least two age subgroups. subgroup 4a comprises grain w, dated to 2683 mya, and grain f, dated to 2775 mya. subgroup 4b consists of grain z, dated to ca. 3600 mya. the last one is the oldest single-zircon age so far obtained in svalbard. all grains are short prismatic with well-developed smooth facets and sharp edges due to younger overgrowth. fig 6. histograms of the single-zircon pb ages from north-western spitsbergen. only plateau ages are used. (a) biscayarhalvøya– holtedahlfonna zone (45; this paper). (b) north-west migmatite region (36; ohta et al. 2002). (a) (b) 261ohta et al. 2003: polar research 22(2), 247–265 discussion in all, 54 zircon grains have been analysed by the single-grain zircon pb evaporation method in this study (fig. 6a). previous isotopic dating results are incorporated in this discussion (table 1). the regional discussion takes into account recent dating results from north-west spitsbergen (fig. 6b). a topographic horst today, the bhz was a graben during latest silurian (?)–devonian time. some k–ar ages of ca. 370 my (gayer et al. 1966) may refl ect the activity of faults and the formation of the anticline structure during the svalbardian event in late devonian (orvin 1940). the hannabreen fault is the boundary between the east verging shb and the west verging nhb subzones. together with the hannabreen fault— the two boundary faults of the graben—the raudfjorden–monacobreen and breibogen faults, form an n-shaped pattern, suggesting a late postdevonian dextral faulting. the oppositely verging duplex structures of the two subzones are evidently older than the deposition of the siktefjellet group. caledonian thermal events, ca. 400 480 mya, have been detected by the k–ar (gayer et al. 1966), 40ar/39ar, rb–sr (dall meyer et al. 1990) and u–pb sphene dating methods (gromet & gee 1998) in this zone. however, no caledonian plateau age has been obtained by the present method. caledonian and older events relating to the nbh and sbh are discussed below. nbh three lithotectonic units of this subzone—the richardalen, montblanc and biscayarhuken units—are repeatedly thrust to the wsw direction, and are thought to get younger in the following order (gee & hjelle 1966; gjelsvik 1979). biscayarhuken unit. the low grade psammitic phyllites of this unit are intruded by subconcordant sheets of ca. 961 my old granite on the southern island of hesteskoholmen, northern liefdefjorden (ohta & larionov 1998). the granite is brittly sheared, and has local oblique contacts to the cleavages of the host phyllites. accordingly, the sedimentary protoliths of the phyllites of the biskayarhuken unit are older than ca. 961 my, i.e. mesoproterozoic. the older age limit of the protoliths is unknown. imprint of the caledonian thermal event is indicated by a biotite k–ar age of ca. 431 my in the north-eastern part of the subzone (gayer et al. 1966), but this event did not disturbed the u–pb isotope system. montblanc unit. this unit occupy the middle structural position among the three lithotectonic units of nbh. the solanderfjellet micaceous schists studied in this work have been correlated with the montblanc unit (gee 1966a; gee & hjelle 1966; peucat et al. 1989; dallmeyer et al. 1990). the youngest detrital zircon from the analysed micaceous schist is 938 my old; accordingly, the age of the sedimentary protoliths of the schist is neoproterozoic. there is no sign of vendian tilloids and thick lower palaeozoic carbonate rocks in this unit. zircon grains with the grenvillian ages from the solanderfjellet micaceous schist (938 1080 my; 28 % of the analysed grains) may show two age clusters, separated by a 60 my interval from 985 mya to 1047 mya. ohta et al. (2002) argued for two phases of zircon formation during the grenvillian period in svalbard: an early igneous event (the vimsodden quartz porphyry and rhyolite, > 1100 mya, in south-west spitsbergen; balašov et al. 1995; and the kapp hansteen quartz porphyry, 950 mya, in north-western nordaustlandet; johansson et al. 1996) and a later metamorphic event (isbjørnhamna schists, 930 mya, south-west spitsbergen; barašov et al. 1996b; and the kontaktberget granite, 939 mya, in north-west nordaustlandet; gee et al 1995). the age clusters inferred in the present samples are conformable with subdivision inferred for other areas of svalbard. the grains with the grenvillian ages, in the broad sense (ca. 940 1080 mya), and late palaeoproterozoic ages (ca. 1600 1950 mya) constitute 28 and 52 %, respectively, of the analysed grains. this suggests that the source areas consist of the rocks with these ages. the grenvillian zircon grains show a low degree of abrasion, suggesting a single depositional process and relatively short transport, while the grains with older ages are strongly abraded. late caledonian thermal records, from ca. 400 440 mya, have been provided by 40ar/39ar and rb–sr ages (dallmeyer et al. 1990), although no early caledonian ages (ca. 460 480 my; e.g. ohta et al. 1979) have been reported from this unit, except for a 458.3 ± 2.4 my sphene u–pb age (gromet & gee 1998). two 40ar/39ar hornblende ages—506 and 538 my—were reported 262 single-grain zircon dating, north-west spitsbergen by dallmeyer et al. (1990), but their geological meaning is unknown. the lithological correlation of the solanderfjellet schists with those of the prototype montblanc unit, exposed in the montblanc area ca. 3 km east of solanderfjellet (gee 1966a), is uncertain. richarddalen unit the gneisses of this unit were intruded by a porphyritic granite (age range of 937 981 my), which were later metamorphosed into augen gneisses and mylonites, before the intrusion of the 955 my old, unfoliated corona gabbro (peucat et al. 1989). rounded shapes of the dated zircon grains from the metagranite sample can be explained by this metamorphism. therefore, a magmatic age of the porphyritic granite of ca. 981 my and the metamorphic age of ca. 955 my are inferred. zircon grains with these ages show similar ages at all evaporation steps of analyses (fig. 2), indicating that they are free from inherited inclusion in the core. the age of the sedimentary protoliths of the richarddalen gneisses is older than 981 my, i.e. mesoproterozoic or older. there are many uncertainties regarding the presence of an early caledonian record in the rocks of the richarddalen unit (dallmeyer et al. 1990; gromet & gee 1998), which contains retrogressed eclogites (gee 1966a, b; hesbøl 1996). there are a few relicts of eclogite facies minerals, but most rocks were strongly reworked at high pressure granulite facies conditions (s. elvevold, pers. comm.). late caledonian reworking is demonstrated by the k–ar, 40ar/39ar and rb–sr mica whole rock ages (gayer et al. 1966; dallmeyer et al. 1990). to summarize the nbh: the richarddalen and biscayarhuken units have mesoproterozoic or older sedimentary protoliths. both were intruded by 960 980 my old granites and variously metamorphosed during the grenvillian period. difference in structural levels during and after grenvillian times may explain their different lithological characteristics. the richarddalen unit, being intruded by basic and felsic rocks around 620 660 my ago (peucat et al. 1989), was metamorphosed under high p–t conditions in a deep crust during early caledonian phase, older than ca. 455 480 mya (gromet & gee 1998). in contrast, the biscay arhuken unit, which was not intruded by basic igneous rocks, has no record of caledonian metamorphism higher than lower amphibolite facies, which is conformable with the k–ar and rb–sr isotope closure temperatures, 350 500 °c (hames & bowring 1995; dickin 1997). the solanderfjellet micaceous schists have neo proterozoic sedimentary protoliths. however, the correlation of the schists with the montblanc unit at the type locality is uncertain and the protolith age of the montblanc unit there is unknown. thus, the three lithotectonic units of the biscayarfonna complex have different histories and were brought into the present duplex confi guration by west verging compressions after the middle silurian during the late caledonian period, before the sedimentation of the siktefjellet group in the latest silurian (?) to the earliest devonian time. sbh the mesoscopic structures of the pre-devonian rocks within both limbs of the anticline in the sbh are complex brittle duplexes in the pelitic schists and gneisses and ductile isoclinal folds in the marbles, both verging to the east (piepjohn & thiedig 1994, 1995, 1997; ohta et al. 1995). the tectonic transport direction is opposite to that of the nbh. some brittle shear boundaries of the duplex units penetrate into the migmatites, while thin aplite veins of caledonian grey granite affi nity cut slightly oblique to the foliation of the gneisses within the duplex units but do not cut the brittle shear boundaries. devonian strata thrust onto the duplex structures and postdate the latest felsic igneous activity. on the middle island of lernerøyane in southern liefdefjorden, the migmatites have feldspar porphyroblastic textures and show a rapid transition from the schists and gneisses in the west. in contrast, abrupt transition from schists and gneisses to agmatitic migmatites is characteristic of the eastern contacts, though the contacts are often sheared. this asymmetric transition refl ects the eastward verging tectonics of the sbh and generally observed in the west of bockfjorden. defi nitely younger, unfoliated grey granite sharply cuts the migmatites. the sample rock used for the present zircon dating cuts the migmatites (fig. 4), and is itself cut by a tourmaline-bearing pegmatitic dyke, which is an affi nity of the grey granite. it is not clear from fi eld relations whether the sample 263ohta et al. 2003: polar research 22(2), 247–265 rock is mobilized neosome of the migmatite or a grey granite contaminating signifi cant amount of migmatitic material. caledonian ages ages around 560 850 my, obtained from the beginning steps of evaporation, indicate caledonian overgrowth or pb-loss of zircon around the grain margins. the latest caledonian thermal event was accompanied with the emplacement of grey granite in the anticlinal crest, ca. 410 430 mya in adjacent north-western spitsbergen (ohta et al. 2002). no sign of an early caledonian phase has been obtained in the sbh. grenvillian ages circa 942 1097 my old zircon grains from the granitic neosome are the most numerous of the grains analysed: 40 % of obtained plateau ages. these have clear igneous growth zoning and inclusions of euhedral crystals and liquid and/ or gas, and these ages could represent crystallization of the zircon from a granitic melt during high grade grenvillian regional metamorphism. accordingly, the age of the sedimentary protoliths of the schists, gneisses and migmatitic paleosomes is considered to be older than ca. 940 my. however, if the presence of a core in one of these grains (grain b with a plateau age of 946 ± 6 my) and rounded outlines of others (grains e, 959 ± 3 my and o, 947 ± 4 my) indicate that these grains are detrital, then the protoliths can be neoproterozoic, similar to the solanderfjellet schists in the nbh. grain g (1063 my old) is evidently rounded and may be the youngest detrital grain so far obtained, though later caledonian resorption origin of the outline is not negligible. to solve the problem of migmatization age, more detailed cathode luminescence examination and ion microprobe spot analysis are needed. two age clusters may be recognized in the grenvillian age range: ca. 950 my (metamorphism) and ca. 1080 my (igneous) phases, consistent with the zircon grains of the solanderfjellet micaceous schist. the age of the marbles overlying the schists and gneisses is unknown. however, they are involved in the same mesoscopic structures as the schists and gneisses and are included as enclaves in the gran itic neosomes, hence their protolith age is considered to be mesoproterozoic. no neoproterozoic zircon age younger than 942 my has been obtained in the sbh. mesoproterozoic ages an igneous event can be recognized from the ages of ca. 1320 my in the granitic neosome sample. this grain has a subhedral shape, due to either overgrowth or weak abrasion during sedimentation. a grain with the age of > 1509 my (grain k) belongs to an older thermal event. a group of zircon grains with ages of ca. 1353 1370 my has been reported from the lower devonian tuffi tes (hellman et al. 1998; table 1), suggesting mesoproterozoic rocks below the surface of north-western sbh. latest palaeoproterozoic and older ages the age group of 1636 1750 my is another large zircon age population, constituting 33 % of obtained plateau ages. grains older than 1636 my show rounded outlines (detrital features), while some are subhedral, due to various degree of overgrowth. a notably high proportion of dated zircon grains are in this age range, similar to the same characteristics of the nbh and north-western spitsbergen gneissose migmatites (fig 6) (balašov et al. 1996b; ohta et al. 2002). granitoids in the western half of ny-friesland, ca. 60 km east of the bhz, are dated to ca. 1750 mya (e.g. gee et al. 1994; johansson et al. 1995; johansson & larionov 1996). such areas could be candidates for the sources of zircon grains with these ages. two archean age groups can be seen among the obtained ages: ca. 2.6 2.8 gya and ca. 3.6 gya. a minimum age of >2.9 gya was obtained from a migmatite neosome of hamiltonbukta, northwestern coast of raudfjorden, ca. 1.5 km west of the raudfjorden–monacobreen fault (ohta et al. 2002). the oldest zircon age (grain z, 3.6 gya) from the granitic neosome sample is a relatively good plateau age; this is the oldest single-zircon age so far obtained in svalbard. conclusions the following general conclusions can be drawn from the single-zircon pb ages obtained by this study and previous dating results. 264 single-grain zircon dating, north-west spitsbergen (1) zircon grains with grenvillian ages constitute the largest population among the analysed grains, indicating thermal events in that period. (2) caledonian growth of zircon is limited to minor overgrowth on older grains. (3) in the nbh, the sedimentary protoliths of the richarddalen and biscayarhuken units are mesoproterozoic, while that of the solanderfjellet schists of the montblanc unit is neoproterozoic. the correlation between the solanderfjellet micaceous schists and the prototype montblanc unit is questioned. (4) the richarddalen unit is intruded by the porphyritic granites, which were successively metamorphosed into augen gneisses and mylonites during the grenvillian period. (5) the biscayarhuken unit was metamorphosed under low grade conditions during the gren villian period, as the cleavages are cut by the 955 my old granite, and has not experienced any higher metamorphism since that time, though it was involved in the caledonian deformations. (6) the protolith age of the schists, gneisses, migmatites and marbles in the sbh is possibly of mesoproterozoic, although a neoproterozoic age can not be ruled out, since the origin of the rounded shapes of the zircon grains is unclear. (7) extensive exposures of latest palaeoproterozoic crystalline rocks are inferred to be the source areas of all the sedimentary protoliths. (8) the population frequency of the obtained ages from the bhz (fig. 6a) is generally similar to that of the north-western spitsbergen (fig. 6b) (ohta 1992; balašov et al. 1996b; ohta et al. 2002), but markedly different from the western half of ny-friesland, which comprise latest palaeoproterozoic granitoids and lack grenvillian rocks. acknowledgements.—the swedish museum of natural history, stockholm, kindly provided the isotopic analysis facility, and the mineralogical–geological museum, university of oslo, provided the bulk rock analyses. we have benefi ted from many critical discussions have been made by german and russian colleagues who worked in this area. we are grateful to m. bjornerud, laurence university, wisconsin, and synnøve elvevold, norwegian polar institute, for language improvements. many constructive comments and language corrections by the referees are also acknowledged. references amundsen, h. e. f., griffi n, w. l. & o’reilly, s. y. 1987: the lower crust and the upper mantle beneath northwestern spitsbergen: evidence from xenoliths and geophysics. tectonophysics 139, 169–185. balašov, j. a., peucat, j. j., tebenkov, a. m., ohta, y., larionov, a. n. , sirotkin, a. n. & bjornerud, m. 1996a: rb–sr whole rock and u–pb zircon datings of the granitic-gabbroic rocks from the skålfjellet subgroup, southwest spitsbergen. polar res. 15, 167–181. balašov, j. a., peucat, j. j., tebenkov, a. m., ohta, y. & sirotkin, a. n. 1996b: additional rb–sr and single-grain zircon datings of caledonian granitoid rocks from albert i land, northwest spitsbergen. polar res. 15, 153–165. balašov, j. a., tebenkov, a. m., ohta, y., larionov, a. n. sirot kin, a. n., gannibal, l. f. & ryungenen, g. i. 1995: grenvillian u–pb zircon age of quartz porphyry and rhyolite clasts in a metaconglomerate at vimsodden, southwestern spitsbergen. polar res. 14, 291–302. cornell, d., åberg, a., schersten, a. & armstrong, r. 1998: the canute model for ion-probe u–pb zircon dating and its application to the borås mafi c intrusion. paper presented at the 23rd nordic geological winter meeting, århus, denmark, 13–16 january 1998. abstract volume, p. 53. dallmeyer, r. d., peucat, j. j. & ohta, y. 1990: tectonothermal evolution of contrasting metamorphic complexes in northwest spitsbergen (biskayerhalvøya): evidence from 40ar/39ar and rb–sr mineral ages. geol. soc. am. bull. 102, 653–663. dickin, a. p. 1997: radiogenic isotope geology. cambridge: cambridge university press. friend, p. f. & moody-stuart, m. 1972: sedimentation of the wood bay formation (devonian) of spitsbergen: regional analysis of a late orogenc basin. nor. polarinst. skr. 157. gayer, r. a., gee, d. g., harland, w. b., miller, j. a., spall, h. r., wallis, r. h. & winsnes, t. s. 1966: radiometric age determinations on rocks from spitsbergen. nor. polarinst. skr. 137. gee, d. g. 1966a: the structural geology of the biskayerhuken peninsula, north spitsbergen. phd thesis, university of cambridge. gee, d. g. 1966b: a note on the occurrence of eclogite in spitsbergen. nor. polarinst. årb. 1964, 240–241. gee, d. g. 1972: late caledonian (haakonian) movements in northern spitsbergen. nor. polarinst. årb. 1970, 92–101. gee, d. g., björklund, l. & stølen, l.-k. 1994: early proterozoic basement in ny friesland—implication for the caledonian tectonics of svalbard. tectonophysics 231, 171–182. gee, d. g. & hjelle, a. 1966: on the crystalline rocks of north-west spitsbergen. nor. polarinst. årb. 1964, 31–45. gee, d. g., johansson, l., ohta, y., tebenkov, a. m., krasilčhikov, a. a., larionov, a. n., gannibal, l. f. & ryungenen, g. i. 1995: grenvillian basement and a major unconformity within the caldonides of nordaustlandet, svalbard. precambrian res. 70, 215–234. gee, d. g. & moody-stuart, m. 1966: the base of the old red sandstone in central north haakon vii land, spitsbergen. nor. polarinst. årb. 1964, 57–68. gjelsvik, t. 1979: the hecla hoek ridge of the devonian graben between liefdefjorden and holtedahlfonna, spitsbergen. the geological development of svalbard during the precambrian, lower palaeozoic, and devonian. sym265ohta et al. 2003: polar research 22(2), 247–265 posium on svalbard’s geology, oslo, 2–5 june 1975. nor. polarinst. skr. 167, 63–71. gromet, l. p. & gee, d. g. 1998: an evaluation of the age of high-grade metamorphism in the caledonides of biskayerhalvøya, nw svalbard . geol. fören. stockh. förh. 120, 199–208. hames, w. e. & bowring, s. a. 1995: an empirical evaluation of the argon diffusion geometry in muscovite. earth planet. sci. lett. 124, 161–167. harland, w. b. 1997: the geology of svalbard. geol. soc. mem. 17. london: the geological society. hellman, f. j., gee, d. g., gjelsvik, t. & tebenkov, a. m. 1998: provenance and tectonic implications of paleoproterozoic (c. 1740 ma) quartz porphyry clasts in the basal old red sandstone (lilljeborgfjellet conglomerate formation) of northwestern svalbard’s caledonides. geol. mag. 135, 755–768. hesbøl, r.-m. 1996: retrograded eclogites of the richarddalen complex, nw spitsbergen—petrology and p/t conditions. ms thesis 71. geological institute, university of lund. hjelle, a. 1979: aspects of geology of northwest spitsbergen. the geological development of svalbard during the precambrian, lower palaeozoic, and devonian. symposium on svalbard’s geology, oslo, 2–5 june 1975. nor. polarinst. skr. 167, 37–62. hjelle, a. & lauritzen, ø. 1982: geological map svalbard 1: 500.000. sheet 3g spitsbergen northern part. nor. polarinst. skr. 154-c. hjelle, a. & ohta, y. 1974: contribution to the geology of north western spitsbergen. nor. polarinst. skr. 158. hoel, a. 1914: nouvelles observations sur le district volcanique du spitsbergen du nord. (new observations in the volcanic district of northern spitsbergen.) viden skaps selskapet skrifter i. matematisk–naturvitenskapelig klasse 9. viden skaps selskapet: kristiania (oslo). holtedahl, o. 1914a: new features in the geology of northwestern spitsbergen. am. j. sci. ser. 4, 37, 415–324. holtedahl, o. 1914b: on the old red sandstone series of north western spitsbergen. in: congress report xii session. pp. 707–712. ottawa: international geological congress. ilys, r. r., ohta,y. & guddingsmo, j. 1995: the downtonian and devonian vertebrates of spitsbergen. xv. new heterostracans from the lower devonian red bay group, northern spitsbergen. polar res. 14, 33–42. johansson, å., gee, d. g., björklund, l. & witt-nilsson, p. 1995: isotope studies of granitoids from the bangenhuk formation, ny-friesland orogen, svalbard . geol. mag. 132, 303–320. johansson, å. & larionov, a. n. 1996: u–pb ages from the eastern terrane of the svalbard caledonides—evidence for palaeoproterozoic, grenvillian and caledonian tectonism. geol. fören. stockh. förh. 118, a-38–39. kober, b. 1986: whole grain evaporation for 207pb/206pb age investigation on single zircons using a double fi lament thermal ion source. contrib. miner. petrol. 93, 482–490. kober, b. 1987: single-zircon evaporation combined with pb+ emitter bedding for 207pb/206pb-age investigation using thermal ion mass spectrometry, and implications to zirconology. contrib. miner. petrol. 96, 63–71. ludwig, k. r. 1991: isoplot—a plotting and regression program for radiogenic-isotope data, version 2.56, u.s. geol. surv. open-fi le rep. 91–445. maniar, p. d. & piccoli, p. m. 1989: tectonic discrimination of granitoids. geol. soc. am. bull. 101, 635–643. ohta, y. 1979: blue schists from motalafjella, western spitsbergen. the geological development of svalbard during the precambrian, lower palaeozoic, and devonian. symposium on svalbard’s geology, oslo, 2–5 june 1975. nor. polarinst. skr. 167, 117-217. ohta, y. 1992: recent understanding of the svalbard basement in the light of new radiometric age determination. in w. k. dallmann et al. (eds.): post caledonian tectonic evolution of svalbard. nor. geol. tidsskr. 72, 1–5. ohta, y., dallmeyer, r. d. & peucat, j. j. 1989: caledonian terraines in svalbard. geol. soc. am. spec. pap. 230, 1–15. ohta, y., gjelsvik, t. & mccann, a. 1995: hornbækpollen thrust zone in liefdefjorden, nw spitsbergen. geonytt 95-1, 55. ohta, y. & larionov, a. n. 1998: grenvillian single-grain zircon pb age of a granitic rock from the southern island of hesteskoholmen, liefdefjorden, northwestern spitsbergen, svalbard. polar res. 17, 145–154. ohta, y., larionov, a. n., tebenkov, a. m., lepvrier, c., maluski, h., lange, m. & hellebrandt, b. 2002: singlegrain zircon and 40ar/39ar datings of the metamorphic and granitic rocks in nw spitsbergen. polar res. 21, 73–89. orvin, a. k. 1940: outline of geological history of spitsbergen. skrifter om svalbard og ishavet 78. oslo: norway’s svalbard and arctic ocean research survey (predecessor of the norwegian polar institute). peucat, j. j., ohta, y., gee, d. g. & bernard-griffi ths, j. 1989: u–pb, sr and nd evidence for grenvillian and latest proterozoic tectonothermal activity in the spitsbergen caledonides, arctic ocean. lithos 22, 275–285. piepjohn, k. & thiedig. f. 1994: geologische und tektonische entwicklung der germaniahalvøya, haakon vii land, nw-spitzbergen (svalbard). (geological and tectonic developments of germania peninsula, haakon vii land, north-west spitsbergen, svalbard.) in w. d. blümei (ed.): geowissenschaftliche spitzbergen-expedition 1990–1992 (spe 90-92)liefde-, woodund bockfjord/nw-spitzbergen. z. geomorph. n.f., suppl.bd. 79, 19–29. berlin. piepjohn, k & thiedig, f. 1995: tektonische entwicklung des kristallinen basements im liefdefjorden-gebiet, nwsvalbard. (tectonic development of crystalline basements in the liefdefjorden area, north-west spitsbergen.) münst. forsch. geol. paläontol. 77, 1–25. piepjohn, k. & thiedig, f. 1997: erläuterung zur geologischen kart 1: 50,000 der germaniahalvøya, haakon vii land, spitzbergen (svalbard). (explanation of the geological map 1:50,000, germania peninsula, haakon vii land, spitsbergen, svalbard.) münst. forsch. geol. paläontol. 82, 39–52. skjelkvåle, b.-l., amundsen, h. e. f., o’reilly, s. y., griffi n, w. l. & gjelsvik, t. 1989: a primitive alkali basaltic stratovolcano and associated eruptive centres, northwestern spitsbergen: volcanology and tectonic signifi cance. j. volcanol. geotherm. res. 37, 1–19. stacey, j. s. & kramers, j. d. 1975: approximation of terrestrial lead isotope evolution by a two-stage method. earth planet. sci. lett. 26, 207–221. wyss, m., hermann, j., müntener, o. & benning, l. 1998: polyphase structural, intrusive and metamorphic evolution of the bockfjorden area, nw spitsbergen. sweizelische miner. petrogr. mitt. 78, 87–106. laptikhovsky.indd 395laptikhovsky & arkhipkin 2003: polar research 22(2), 395–397 squid of the family cranchiidae are among the most abundant squids in the world ocean. juveniles and immature cranchiids inhabit mainly epipelagic and mesopelagic waters, whereas adults descend upon maturation into bathypelagic waters (nesis 1985). this has limited the capture of mature animals as deepwater pelagic trawls are rarely performed during research cruises. data on the reproductive biology of cranchiids remain extremely scarce. to date, the only full description of the reproductive system of a mature prespawning cranchiid female was of teuthowenia pellucida (voss 1985). the squid galiteuthis glacialis (chun 1906) is numerous south of the antarctic polar front (nesis 1985; nesis et al. 1998). as with other cranchiids, adults occur in the lower mesopelagic and bathypelagic zones (nesis et al. 1998), whereas post-spawning moribund squids become positively buoyant and appear near the surface, where they fall prey to seabirds (croxall & prince 1996). mature females of g. glacialis with spermatophores embedded in their mantles have been caught twice between 800 and 1800 m depth (mcsweeny 1978; lu & williams 1994), but were not been described. recently, two dead spent females (425 and 475 mm mantle length) were collected from an ice hole over ca. 1900 m depth in the western part of the weddell sea (nesis et al. 1998). mature females of this species have not been described yet. this report describes the reproductive system of a mature female which was caught by the rv dorada using a semi-pelagic 3 hr engel trawl on 1 november 2002 at a depth horizon of 976 1001 m over bottom depths of 1582 2378 m at 53° 22.1' 53° 29.0' s, 58° 16.7' 58° 03'9 w. the animal, which had a mantle length of 430 mm, had no head—it had probably been picked off by an albatross during hauling, but the body was not seriously damaged. the squid was preserved in 10 % buffered formalin solution and then transferred into 70 % ethanol. during examination, three samples (total 2.1 g) were taken from the intact part of the ovary (8.8 g) and all oocytes were counted. another part of the reproductive features of a mature female of the deep sea planktonic squid galiteuthis glacialis (cephalopoda: cranchiidae) from the southern ocean vladimir laptikhovsky & alexander arkhipkin a mature female galiteuthis glacialis (430 mm mantle length) was caught south of the falkland islands (53° s, 58° w) at a depth of 976 1001 m over a bottom depth of 1582 2378 m. a total of 8 spermatangia (15-19 mm in length) were found inserted into the mantle wall, which was of gelatinous consistency. its ovary contained 3 605 ± 42 oocytes, mostly 2.2 2.5 mm in length, and there were 21 ripe eggs (3.0 3.2 × 2.2 2.7 mm) in the oviducts. only one resorpting oocyte (1.4 mm) was found. this is the only description of a mature female of this species, though two spent females have been previously described and three more mentioned by other authors. v. laptikhovsky & a. arkhipkin, falkland islands government fisheries dept., box 598, stanley, falkland islands, vlaptikhovsky@fi sheries.gov.f k. research note 396 the reproductive features of a mature female galiteuthis glacialis the gonad (6.0 g) was fragmented due to ovary fragility (nesis et al. 1998), but no part of the ovary was lost. all oocytes from the fragmented part were counted by eye. oocytes from a random sample of 106 oocytes were measured along the major axis within 0.1 mm. among others, two ripe eggs and one resorpting oocyte were found in the intact part of the ovary. the mature female had a spindle-shaped gelatinous mantle with an attenuated posterior tip and oval-shaped fi n as has been observed in spent females (nesis et al. 1998). the skin of the body was mostly intact, with a few marks from the trawl mesh. the mantle was covered by pale brown and whitish stripes and blotches. halfway between the anterior and posterior parts of the mantle, eight spermatangia of 15 19 mm length were found inserted into the mantle wall under the skin (fig. 1). they were parallel to the longitudinal body axis at the left side of the body and appeared to be from a single copulation. mantle tissue around each spermatangium was more opaque. in some places, there were similar opaque traces with a groove corresponding to lost or spent spermatangium (fig. 1). however, as there was a lack of empty follicular sheaths in the ovary it is quite unlikely this female had been spawning. spermatangia placement on the body was different from that observed (near anterior margin of the mantle) in the spent females from the weddel sea. the stomach was empty, without any traces of food. similar to the spent females, the digestive gland was spindle-shaped and rigid (nesis et al. 1998). there were 21 ripe eggs of 3.0 3.2 × 2.2 2.7 mm in the oviducts. the ovary (total weight 14.8 g) contained 3605 ± 42 oocytes. empty follicles were not found probably because of the relatively small numbers of ovulated eggs (21). only one resorbing egg (1.4 mm length) was noticed among a subsample of 1967 counted oocytes. the oocytes of 2.2 2.5 mm predominated (96.6 %) in the ovary (fig. 2), indicating synchronous egg release. our data on egg size and fecundity are consistent with those from the two spent females from the weddell sea, with residual egg size of 3.3 × 2.4 mm and ovaries containing 3400 and 2100 empty follicles. in contrast to our specimen, fig. 1. implanted spermatophores (spermatangia) in the mantle wall of a mature female galiteuthis glacialis. the skin near the spermatangia is partially removed. abbreviations: sp–spermatangia, sg–vacant grooves of spermatangia, ot–opaque tissue surrounding spermatangia. 397laptikhovsky & arkhipkin 2003: polar research 22(2), 395–397 the spent females from the weddell sea had a large amount of small resorpting oocytes of 0.9 1.4 mm (10 600 20 900), indicating high initial potential fecundity. the resorption of the potential fecundity during female maturation, when up to 85 % of the initial oocyte stock can disappear, is known for the other deep sea pelagic squids of the family histioteuthidae (laptikhovsky 2001). one of the reasons for this resorption could be an adjustment of potential fecundity to the actual body size attained by the adult female. big differences in the number of resorbing oocytes between the falkland and weddell sea g. glacialis females sharply contrasted with nearly equal actual fecundity in all females, and could indicate differences in the initial potential fecundity between sub-antarctic and antarctic populations. references croxall, j. p. & prince, p. a. 1996: cephalopods as a prey. i. seabirds. phil. trans. r. soc. lond. ser. b 351, 1023–1043. laptikhovsky, v. v. 2001: first data on ovary maturation and fecundity in the squid family histioteuthidae. sci. mar. 65, 127–129. lu, c. c. & williams, r. 1994: contribution to the biology of squids in the prydz bay region, antarctica. antarct. sci. 6, 223–229. mcsweeney, e. s. 1978: systematics and morphology of the antarctic cranchiid squid galiteuthis glacialis (chun). biol. antarct. seas, vii antarct. res. ser. 7, 1–39. nesis, k n. 1985: okeanicheskie golovonogie molluski: ras prostranenie, zhiznennye formy i evolutsia. (oceanic cephalopod molluscs: distribution, life forms and evolution.) moscow: nauka press. nesis, k. n., nigmatullin, c. m. & nikitina, i. v. 1998: spent females of deepwater squid galiteuthis glacialis under the ice at the surface of the weddell sea (antarctic). j. zool. 244, 185–200. voss, n. a. 1985: systematics, biology and biogeography of the cranchiid cephalopod genus teuthowenia (oegopsida). bull. mar. sci. 36, 1–85. fig. 2. length–frequency distribution of oocytes in the ovary of a mature female galiteuthis glacialis. coastal cliff temperatures related to the potential for cryogenic weathering processes, western spitsbergen, svalbard rune strand 0 d e g a r d and johan ludvig sollid 0deglrd, r. s. & sollid, j. l. 1993: coastal cliff temperatures related t o the potential for cryogenic weathering processes, western spitsbergen, svalbard. polar research 12(1), 95-106. n the main purpose of this research was to measure the near surface ground temperatures and describe the main characteristics of the thermal regime of a sheltered arctic coastal cliff. measurements were made near ny-alesund, western spitsbergen, svalbard (79"n, 12"e). in a transect across sediments on top of a coastal cliff, in a 8 m high coastal cliff and across the beach below the cliff. temperatures were logged hourly from august 1987 to august 1988. a local snow cover of 1-4 m on the beach had a strong i d u e n c e on surface heat exchange, and hence the dynamics of the ground thermal regime. late winter temperatures in the cliff and backshore sediments were stable and ranged from -5°c to -9°c. at the first snow melt events in spring there was a large heat flux into the ground due to the release of latent heat from refreezing of meltwater. the interpretation of the temperature records leads to a discussion on some aspects of cryogenic weathering. the snow-melt period in spring and summer may be a period of rock fracturing, based on the model of segregation ice growth at subzero temperatures. steep temperature gradients and available meltwater at the surface favor water migration in the heavily fractured dolomitic limestone even at the low hydraulic conductivities expected at below zero temperatures. r . s. 0degdrd and j . l. sollid, department of physical geography, university of oslo, p . o . box 1042 blindern, n-0316 oslo, norway introduction svalbard comprises a group of islands situated between latitudes 74"n and 81"n and longitudes 10"e and 35"e. the western coast of the main island spitsbergen is exposed t o relatively warm atlantic water. maps of the coastal geomorphology of svalbard, excluding nordaustlandet, show well developed coastal cliffs along 25% of the coastline (0degard et al. 1987; h0gvard & sollid 1988a, b, 1989,1990,1991,1992). low vertical coastal cliffs with erosion in bedrock are most frequent in fjord areas in northwestern spitsbergen, including isfjorden, and in the inner parts of storfjorden on the eastern coast. the fjords generally have a low energy coast as the ice-foot and sea ice protect the cliffs from wave energy during most of the year. coastlines with long fetch and less sea ice along the headlands normally have pocket beaches with low bedrock outcrops or continuous beaches. submerged strandflat areas along most of the outer western coast of spitsbergen reduce the amount of wave energy reaching the shore. arctic coastal rock cliffs are subjected t o diverse subaerial and marine weathering processes. frost weathering was already proposed by hogbom (1914) and nansen (1922) t o be an important process in the formation of the coastal cliffs characteristic of spitsbergen fjords. nansen also suggested that the strandflat forms by the interaction of frost weathering and marine pro cesses at coastal rock cliffs, with frost weathering as the main fracturing agent and marine processes responsible for the removal and transport of material. the strandflat belongs to high latitude coasts, and its origin has been discussed by reusch (1894), ahlmann (1919), nansen (1922) and sev eral others. the fractured appearance of the sheltered coastal rock walls and the amount of angular rock fragments that accumulate on snow and ice-foot during spring show that subaerial mechanical weathering is active (0. liestel pers. commun.). in sheltered areas snow and ice usually persist until late autumn just above high tide, indicating that limited amounts of marine energy reach the cliffs in summer. marine erosion at sheltered sites 96 r. s . q)deg&rd & j . l. sollid is probably restricted to storms recurring at inter vals of several years. during the entire research period of one year the sediments close to the investigated cliff were not disturbed by waves. no earlier quantitative measurements of coastal cliff retreat in svalbard are known to the authors. in the research area the abrasion platform is 10-15 m wide. an average holocene retreat rate is difficult to calculate due to limited knowledge of the sea level after the tapes trans gression (forman et al. 1987) and to the possibility of a pre-holocene cliff being reoccupied by the present sea level. no measurements of present weathering rates were attempted. the main purpose of this research was to meas ure the near surface ground temperatures and describe the main characteristics of the thermal regime of a sheltered arctic coastal cliff. the influence of the macroclimate and local factors such as snow cover and available water are dis cussed. based on the temperature records and a rough evaluation of moisture conditions, some aspects of the potential for cryogenic weathering processes in the rock cliffs of this type are discussed. recent advances in cryogenic weathering research provide guidance for discussing cryo genic weathering based on temperature records. reviews of cryogenic weathering are given by mcgreevy (1981) and lautridou (1988). labora tory research has shown that oscillations around 0°c are less significant than formerly assumed regarding fragmentation of most rocks. labora tory experiments show critical temperatures for rock fracturing from -3°c to below -10°c (mel lor 1973; mcgreevy 1982; lautridou & ozouf 1982; letavernier & ozouf 1987). using a theor etical model of segregation ice growth at subzero temperatures, hallet (1983) showed that the most rapid expansion of preexisting microcracks in an open system in rocks is expected in the interval from -5°c to -15"c, depending on available water, the rock properties and the temperature gradient on the warmer side of the crack. this model has recently been supported by an exper imental study using a porous sandstone (hallet et al. 1991). quantitative analysis of the processes that oper ate in the arcticcoastal zone is extremely difficult. no attempt is made to provide a complete eval uation of the site specific processes. a more com prehensive discussion of the subaerial process would have to include data on the fracture-mech anical properties of different rocks and measure ments of moisture conditions. such data are not available. study area location and setting temperatures were measured at a north-facing dolomitic limestone cliff located on the south side of inner kongsfjorden on the western coast of spitsbergen (fig. 1). the site is moderately exposed to wave energy (figs. 2 and 3). large parts of the coastal cliff have subsequently been removed in the construction of a new quay. the beach was 14 m wide and backed by an 8 m high coastal rock cliff. the study site is located 450m from the meteorological station in ny-alesund. the mean annual air temperature (maat) was -6.o"c in the period 1971-1988. the mean annual ground temperature (magt) is believed to be about -5"c, based on measurements in a former coal mine (orvin 1944). the mean air temperature from september 1987 through august 1988 was -7.6"c, reflecting an unusually cold winter; the september to may average air temperature was the third coldest in 20 years. especially low air temperatures in the period of a thin snow cover in december and january imply lower than average ground temperatures in the research period (fig. 4). snow, ice-foot and sea-ice conditions the snow accumulation in the 1987-1988 season was average provided that winter accumulation on the glacier austre brdggerbreen 3 km from ny-alesund is assumed to be representative of the coastal zone. there is a 20-year record of mass balance from austre brdggerbreen (liestdl 1988; hagen & liest01 1990). no snow depth measurements are available from the meteoro logical station. snow began to accumulate at the foot of the cliff in september, and by the end of october the local snow depth was 2.0 m. snow accumulation reached the top of the cliff (which was usually free of snow until this time) in early december. in mid-december the snow depth at the top of the cliff was 0.25 m. from the end of february the cliff-top snow cover stabilized at 0.55-0.65 m coastal cliff temperatures related to the potential for cryogenic weathering processes 97 fig. 1 . the research site near ny-alesund on the western coast of spitsbergen, svalbard. shaded areas are glaciers. fig. 2 . transect across the investigated site. a nearby coastal cliff at the location of thermistor 7 is included. shaded areas on land are marine beach material. in the intertidal zone the ice-foot and sea ice are shaded. numbers 1 t o 10 show location of thermistors. until 7 may-10 may when the spring melt began (fig. 4). in 1987 snow and ice had not melted by the end of august (fig. 3). this year had the second coldest june, july and august of the previous 20 years. after a summer of average temperatures in 1988, snow and ice remained until the middle of august. the western coast of spitsbergen has semi diurnal tides. at the research site the average maximum range is 1.8m. the maximum tidal range during 15 years of observations in ny-ale sund is 2.3m. the average high tide is 0.6m above mean sea level (t. eiken pers. commun.). in 1987 a tidal ice-foot was formed in sheltered areas of kongsfjorden as an ice terrace at the level of maximum high tide. the ice-foot protected the backshore from nearly all wave energy during the autumn. at the research site the height of the ice foot varied from 0.61 m to 0.77 m above mean sea level. according to wiseman & coleman (1978), there is considerable spatial and temporal varia bility in ice conditions and ice-foot morphology. the inner part of kongsfjorden is usually frozen, at least during some of the winter. there were no storms at the research site during the period without ice-foot and sea ice in autumn 1987 and summer 1988. methods and results thermistors were used for the ground tem perature measurements. the absolute accuracy was estimated to be +o.l"c close to o"c, increas ing to 20.2"c at the ends of the interval 220°c. the resolution was 0.01"c for the whole range. ten thermistors were places in a transect across 5 0 5 10 15 20 2 ' m (from foot of cliff) 98 r. s . gdegdrd di j . l. soilid backshore sediments and across a rock cliff situ ated on the south coast of kongsfjorden, just west of the first quay in ny-alesund (figs. 2 and 3). ground temperatures were measured at hourly intervals from 26 august 1987 to 26 august 1988 at depths ranging from 0.05-1.20111. two additional thermistors recorded temperatures in the outer shell of the cliff face during the summer only (20 may-26 august, 1988). the mean annual values of ground temperature varied from -6.3"c (thermistor 7) on an exposed part of the cliff with little snow cover to -2.9"c (thermistor 10) in shore sediments at mean sea level (fig. 2 and table 1). the average value at the foot of the cliff was -3.9"c. the lowest mean ground temperature of -6.3"c is 1.3"c warmer than the mean air temperature of the same period. thermistors 5 and 6 were placed 3.75 m apart at 0.05 m and 0.35 m depth in the flat area on top fig. 3. view to thc south-west of the study site. the shore and the cliff face north and arc mod erately exposed to wave energy. the upper photo is from 24 may 1988. the locations of thcr mistors 7 , 1 1 and 12 are shown. the dashed line indicates the main section. the lower photo is from late august 1987 and shows snow and ice at the foot of the cliff. of the cliff. the maximum snow depths were 0.75 m and 0.70 m respectively. the mean annual ground temperatures of -5.4"c and -5.o"c were 2.2"c and 2.6"c warmer than the mean air tem peratures of the period. these mean values are probably representative of flat areas with vege tation near the coast. these differences between mean ground and mean air temperature deviate little from those at an alpine permafrost site in southern norway, estimated to range from 2.2"c to 2.4"c in a flat area with a maximum snow depth of 0.50m (0degird et al. 1992). autumn and early winter at thermistor 8 there was only a slight delay in cooling close to wc, indicating a dry freezing in the rock wall. this was in contrast with thermistor 3 at the foot of the cliff and thermistors 6 and 9 coastal cliff temperatures related to the potential f o r cryogenic weathering processes 99 fig. 4. a. snow accumulation on top of the cliff. b. mean monthly air temperatures in the research period, plotted versus mean monthly temperatures in the period 19mto 1988. dashed lines arc t one standard devi ation of mean monthly tem peratures. table 1. average and extreme temperatures. 1987 1988 average maximum maximum depth values maximum minimum rise drop number m "c "c "c "c/h "c/h 1 2 3 4' 5 6 7 8 9' 10 11.' 12" 0.36 0.40 0.60 0.90 0.05 0.35 0.55 0.25 1 .00 1.20 0.05 0.05 -5.5 -4.0 -3.9 -4.0 -5.4 -5.0 -6.3 -4.4 -6.2 -2.9 6.6 6.9 17.8 3.0 1.1 0.0 13.0 4.3 13.5 10.6 0.3 0.1 23.8 23.7 -18.1 -11.8 -6.3 -7.2 -19.2 -11.7 -20.6 -10.6 -9.6 -5.4 -0.2 -1.4 2.23 2.92 0.21 0.28 1.87 0.24 0.36 0.96 0.03 0.12 7.29 6.10 1.12 0.63 0.10 0.45 1.71 0.14 0.43 0.69 0.04 0.09 4.00 3.23 *august 26, 1987 to may 10, 1988. **may 20, 1988 to august 26, 1988. 100 r. s . 0deg&rd & j . l. sollid in sediments on top of the cliff. at the foot of the cliff, water was mainly supplied from snow and ice that melted in situ. the temperature at a depth of 0.6m shows a smooth yearly cycle. a local snow patch in mid-september minimized heat loss to the air, and an area at the base of the cliff remained relatively warm most of the autumn and early winter (fig. 5). thermistor 3 was cooled slowly to a minimum temperature of -6.3"c in the middle of february. the thermistors on the beach and upper part of the cliff showed large fluctuations at subzero temperatures during autumn. the maximum freezing rate was 0.78"c/h. in late october a 0 -5 y 0-10 a e g! l q)-15 e 2 -20 -25 -i -12 1 ' september october november december fig. 5. the upper graph gives air temperatures kom the meteorological record in ny-hesund. only observations at m:oo and 19:oo are plotted. maximum and minimum tem peratures between these observations are not included. the dashed lines indicate 30-day moving averages. the lower graph gives ground temperatures during autumn freeze. the numbers refer to thermistor numbers. period of three days of surface melt occurred (fig. 5) * late winter at the cliff base (thermistor 3), the temperature rose from a minimum of -6.3"c in mid-february to -58°c in mid-april. in late winter thermistor 3 continued t o record low temperatures (fig. 6). temperatures remained below -5°c for more than four months. thermistor 8 in the cliff showed temperatures slightly below those at the foot of the cliff. in march and april temperatures varied between 0.36"c and 0.46"c, corresponding to gradients of o.lcc/m to o.l8"c/m. the other three thermistors on the beach also showed stable i" i -35 ' 0 ........................................................ -a j march april may june july fig. 6. the upper graph gives air temperatures from the meteorological record in ny-hesund. only observations at 07:oo and 19:m) are plotted. maximum and minimum tem peratures between these observations are not included. the dashed lines indicate 30-day moving averages. the lower graph gives ground temperatures during spring thaw. the numbers refers to themistor numbers. coastal cliff temperatures related to the potential for cryogenic weathering processes 101 temperatures from march to april ranging from -4.4"c to -5.6"c. snow-melt period in spring ground temperature records reveal distinct tem perature anomalies during spring on portions of the rock wall not exposed to direct insolation. the ground temperatures at snow-covered sites in late winter were stable until the first snow melt in the beginning of may. as discussed later, it is presumed that release of latent heat from the refreezing of meltwater in the snow cover and sediments caused a steep rise in ground tem perature. at the onset of thaw the rock wall was covered with several metres of snow. in the spring there were two periods of surface melt each fol lowed by surface cooling of bedrock and sedi ments to subzero temperatures (figs. 6 and 7). thermistor 8, in the rock wall at 0.25 m depth, measured surface cooling during most of may, interrupted by short warming periods (fig. 6). the maximum rise in temperature at thermistor 8 was 0.24"c/h, recorded during the second surface melting event. the maximum rise during the first event was not detected because of a break in the record on 10 and 11 may. the maximum rise in temperature in shore sediments at the second period of snow melt was 2.9"c/h at thermistor 2, observed 22 may (fig. 6). the site was covered i 15 temperature gradient'clrn 0 5 ground temperature "c ........................... 1988 i -15 j i april may june fig. 7. ground temperatures and gradients on top of the cliff during the spring thaw in 1988. thermistor 5 (continuous line) at 0.05 m depth and thermistor 6 (dashed-dot line) at 0.35 m depth were placed 3.45 m apart. horizontal heat flow is assumed negligible, and the differences are regarded as near surface temperature gradients during the period of snow-melt. with 2 m of snow. the steep rise is probably caused by percolation and subsequent refreezing of meltwater into the sediment. on 22 may the maximum air temperature was 4.2"c. this was the ninth day of air temperatures above 0°c. the total surface snow melt was 0.15-0.20m, measured on a snow stake on top of the cliff (fig. 4) * near-sutjace measurements in the coastal cliff in summer in addition to the 10 sensors shown in fig. 2, two sensors were placed at a nearby site in the coastal cliff at 0.05 m depth 2.0 m and 3.0 m above the foot of the cliff (fig. 3, thermistors 11 and 12), and measured from 20 may-26 august 1988 (table 1). there was no snow at the thermistor locations. the lower thermistor was placed in a nearby vertical rock wall, the upper in a wall of about 70". the average temperatures were 6.6"c and 6.9"c, which are 2.7"c t o 3.0"c higher than the average air temperature during the same period. the sensor cables were protected by aluminum tape to minimize direct heating by radiation. the rock surface was frequently 8°c t o 10°c warmer than the maximum air temperatures in periods of direct insolation. the maximum rock tempera tures were 23.7"c and 23.8"c. these near surface temperatures (0.05 m depth) on the north-facing coastal cliff exhibit the most drastic temperature fluctuations. rapid temperature changes were recorded during nights when the weather suddenly changed from fog t o direct insolation or vice versa. the fastest tem perature rise was recorded 15 june 1988 from 04:18 to 05:18. the rates for thermistors 11 and 12 were 7.3"c/h and 6.1°c/h, respectively. the meteorological record shows a change from fog to sun at this time. the maximum recorded cooling rates of 4.0°c/h and 3.2"c/h were measured july 24 between 10:34 and 11:34 and may 25 between 04:18 and 0518. discussion interpretation of near surface temperature gradients and heat flow interpretations of the thermal regime in autumn, late winter, spring and late summer are depicted 102 r. s. 0degsrd di j . l . sollid in fig. 8a-d. the ice-foot and later sea ice pro tected the upper inter tidal zone and the back shore from waves during autumn and winter. snow accumulated undisturbed, reaching a maxi mum depth of four t o five metres in february. the accumulation and melting of snow on the beach had a strong local influence on near surface heat flow and moisture conditions during the entire year, from the first snow accumulation in september 1987 until the end of the snow melt in august the following year. autumn and early winter. in early autumn most of the rock cliff cooled rapidly at the surface t o temperatures considerably below 0°c (fig. 8a). average temperature gradients calculated from thermistors 5 and 6, were about 9"c/m in the upper 0.3 m of marine deposits on top of the cliff in november. a local snow patch at the foot of the cliff in september prevented strong surface cooling. late winter. during late autumn and early winter, the snow cover stabilized ground tem peratures and the near surface heat flow on the backshore and in the lower parts of the cliff (fig. 8b). the vertical component of heat flow in the cliff can be calculated from the late winter dif ferences in temperature between thermistor 3 at the foot of the cliff and thermistor 8 in the rock cliff. assuming a thermal conductivity in the bed rock of 2.3 w/mk, the vertical heat-flux ranges from 0.3 to 0.4 w/m2. because of the low rates of heat flow and stable temperatures during two to three months, the measured temperatures in beach sediments probably d o not deviate much from the temperature at the base of the snow (bts) . the surface ground temperature under thick snow cover in late winter is mainly controlled by the temperature of the underlying permafrost (haeberli 1973; haeberli & patzelt 1982). bts measurements might be used as a quick and reli able way to obtain estimates of the permafrost temperature (king et al. 1992). the temperature from february to may at thermistor 3 was less than 1°c colder than the magt at the top of the cliff. the higher late-winter temperatures in beach sediments close to the sea, compared to those at the foot of the cliff, indicate a lateral heat flow from the sea which causes a warmer permafrostclose to the intertidal zone (fig. 8b). .. i 10 9 8 7 46 a5 3 2 1 0 -1 e4 -5 0 5 1 -2 ' -5 0 5 1 -2 ' m (from foot of cliff) fig. 8. ground temperatures in november, april. early june (1-15) and august. numbers at the thermistor locations are average values in the period. dashed lines indicate isothermal lines. the arrow in early june points to a zone of steep surface temperature gradients during snow melt. coastal cliff temperatures related to the potential for cryogenic weathering processes 103 no temperature measurements were made in the intertidal zone. snow-melt period in spring. at the first snow melt events in spring, we infer that the sudden release of latent heat from the refreezing of meltwater caused a large heat flux into the ground. in the cliff top sediments maximum tem perature gradients occurred during the first period of surface melt, with peak values of about 15"c/m calculated from thermistors 5 and 6 (fig. 7). the temperature decreased with depth. in the first week of june the snow pack probably became nearly isothermal at o"c, and thereby buffering strongly the temperature at the rock and sediment surface until the snow melted. a t the top of the cliff the snow remained until late june; at the foot of the cliff until mid-august. during the snow-melt period, the temperature gradient at depth decreased (fig. 7), and hence also the refreezing of meltwater at the surface. near-surface temperature gradients increased abruptly as soon as the snow and ice cover vani shed. near-surface temperatures in the rock wall in sum mer. instantaneous rates of temperature change at the surface were considerably higher than the observed value of 7.3"c/h because of the depth of the measurement (0.05 m) and the long sampling interval (1 hour). large temperature gradients occurred at sudden changes in insolation. more detailed interpretations are difficult on such lim ited temperature data. because of the dependence of the thermal regime on local factors such as sea-ice conditions, ice-foot morphology, moisture conditions and snow cover, care must be taken in generalizing. however, the main characteristics of the observed heat flow in late winter and the surface tem peratures at the onset of thaw are probably typical for large areas of the coast of svalbard. at sites where snow accumulates on the beach, tem peratures approaching mean annual ground tem perature of near coastal areas are probably reached every year at the foot of the cliff in spring before the onset of thaw, independent of the variations in air temperatures and snow cover during autumn. these strongly buffered thermal conditions are probably typical for the fjord areas in northern spitsbergen and the eastern coast. o n the western coast, where the measurements were made, sea-ice conditions are known to show great variability from season t o season. because of the cold winter in 1987/88, there was extensive sea ice during the measuring period. the potential for cryogenic weathering the relation between thermal regime, moisture content and rock fracturing is not fully under stood, and the following discussion is mostly con ceptual. the discussion is restricted t o rock fracturing related to the phase changes of h 2 0 and is based on an interpretation of seasonal changes in ground temperature and heat flow. the importance of diurnal temperature variations and thermal stresses are difficult t o evaluate based on the shallow temperature measurements rec orded in summer. nevertheless, these processes could be important for rock fracturing directly below the surface of the rock wall (hall & hall 1991). lautridou (1988) suggests that bursting in non cracked rocks is caused by the pressure of the water in the core of the rock whose movement is blocked by the freezing front, with absorbed water possibly playing a small additional role. assuming the water pressure arises from the 9 % volumetric expansion when water freezes, great expansive pressure is only possible in a closed system in rocks close t o saturation. whether these conditions are often met in nature is questionable (hall 1986). since no measurements of moisture conditions exist, the potential of a volumetric expansion model cannot be evaluated. both laboratory research and theoretical models show that water migrates toward a single freezing front in rocks in a similar way to what is well known in soils (fukuda 1983; hallet 1983; walder & hallet 1986). this water migration can generate heaving pressures in freezing soils that attain values of more than 18mpa (radd & oertle 1973). the ice pressure in excess of water pressure depends on the temperature at which water freezes. ice pressures necessary to expand microcracks in sound rock are on the order of 10mpa (hallet 1983). in an open system such pressures are only possible at temperatures sev eral degrees below zero. water absorbed on the surface of minerals remains unfrozen at tem peratures considerably below 0°c. the low ice pressures associated with the freezing of water in cracks in an open system close to 0°c have little importance with regard t o rock fracturing. segregation ice growth in cracks at subzero 104 r. s . odegdrd & j . l . sollid temperatures does not require cooling tem peratures. accelerated segregation ice growth can even occur during periods of temperature rise at the rock surface, assuming that water transport is the limiting factor. the hydraulic conductivity at subzero temperatures will increase with rising temperature. this seemingly paradoxical situa tion, that ice growth can be accelerated by surface heating, is discussed by hallet et al. (1991, page 293). the mobility of unfrozen water at subzero tem peratures is critical to the model of segregation ice growth at subzero temperatures. in the exper imental study a porous sandstone was used (hallet et al. 1991). in the field situation described here the hydraulic conductivity along interconnected cracks is probably important in addition to the properties of the rocks. costal cliffs along the coast of svalbard are generally heavily fractured. during the snow-melt period these cracks are mostly ice-filled. williams & smith (1989, page 199) suggest that ice masses in a frozen soil do not represent bamers that would greatly limit soil permeability. the analogy to ice-filled cracks is speculative but could be significant, especially in rocks of low permeability. if continuous air-filled passages exist along the cracks, migration of water vapor can occur. autumn and early winter. the temperature measurements in the rock wall in autumn indi cated a dry freezing with negligible latent heat effects. the rapid freezing of the rock wall prob ably limits segregation ice growth in periods of surface cooling in autumn. due to an early snow cover the foot of the cliff remained relatively warm during autumn, but the sustained tem perature gradients were low and there was prob ably limited available water. conditions considered favorable for segre gation ice growth at subzero temperatures occur during melting periods in autumn, but only for a few days. temperature gradients and moisture conditions during periods of surface melt are dis cussed in more detail below. snow-melt period in spring. at the investigated coastal cliff the temperature gradients and moist ure conditions in the period of snow-melt in spring could lead to segregation ice growth at sustained subzero temperatures according to the model by hallet (1983) because (1) the release of heat from the refreezing of meltwater caused steep gradients with values on the order of 5"c/m to 15"c/m in the outer 0.25111, (2) the temperature of the bedrock just below the surface (-4°c to -6°c) is low enough to cause high ice pressures yet not so low as to hinder water migration significantly, (3) favorable conditions last for several days or weeks, allowing time for segregation ice growth even at low hydraulicconductivities, and (4) when the snow cover has reached 0°c percolating meltwater is available at the rock surface at pressures close to atmospheric pressure (fig. 8c). these thermal and moisture conditions fit the experimental study using acoustic emissions (hal let et al. 1991), except for the calculated tem perature gradients which are lower and the duration which is slightly longer. at the foot of the cliff, the snow-melt period with available water at the surface lasted more than two months. conclusions the main characteristics of the thermal regime are depicted in fig. 8. the ice-foot and sea ice made it possible for a thick snow pack to accumu late undisturbed on the beach. the distribution of snow and ice on the backshore influenced moisture supply and surface heat exchange during most of the year. a local snow patch at the foot of the cliff in mid-september minimized heat loss to the air, and this area remained relatively warm most of the autumn and early winter. in late winter a snow cover of 1-4m stabilized ground temperatures and heat flow. the rock surface temperatures at the onset of thaw ranged from -6°c at the foot to -9°c in upper parts of the cliff (fig. 8b). the first periods of snow melt in spring were characterized by a large heat flux into the ground due to the release of latent heat from refreezing of meltwater. at the foot of the cliff snow and ice remained until august. the described thermal regime in spring and summer is probably typical for this type of coast in northern and eastern svalbard, where sea ice is stable in winter and snow accumulates in front of the cliffs. on the western coast, where the measurements were made, sea-ice conditions are unstable. our understanding of rock fracturing mech anisms related to the thermal regime is incom plete. the interpretation and discussion above actually suggest that the spring and summer snow melt periods are favorable for crack expansion coastal cliff temperatures related to the potential f o r cryogenic weathering processes 105 and rock fracturing in the studied transect. this is based on the model of segregation ice growth at subzero temperatures (hallet 1983; walder & hallet 1986; hallet et al. 1991). at the foot of the cliff favorable temperature gradients and moist ure conditions lasted throughout most of the sum mer, but the temperature gradient decreased from the first snow melt events in the spring until the total disappearance of snow in august. similar conditions also occurred during melting periods in autumn, but only for a few days. the hydraulic conductivity in heavily fractured rocks at subzero temperatures is critical in this model. the importance of thermal stresses, diurnal temperature variations in the outer shell and the potential of volumetric expansion models are dif ficult to evaluate based on the field data. studies of the thermal regime of arctic coastal rock cliffs are continuing in liefdefjorden, northern spits bergen, for comparison with the results from ny h e s u n d . acknowledgements. thanks are expressed to 0. liestel for constructive advice, and to b. lefauconnier who monitored snow melt during spring and early summer. the staff of norsk polarinstitutt and kings bay kull comp. a/s in n y h s u n d gave valuable help in installing and maintaining the equipment. the project rcceived financial support from norsk polarinstitute in 1985, 1987 and 1988. j.-p. lautridou gave constructive com mentson an early draft of the manuscript. additional comments by two anonymous referees improved the paper. references ahlmann, h. w. 1919: geomorphological studies in norway. geogra. ann. i , s 2 5 2 . forman, s., mann, d. h. & miller, g . h. 1987: late wech selian and holocene sea-level history of breggerhalveya, spitsbergen. quat. res. 27. 41-50. fukuda, m. 1983: the pore water pressure profile in porous rocks during freezing. in permafrost, fourth international conference, proceedings. national academy press, wash ington, d.c. pp. 322-327. haeberli, w. 1973: die basis-temperatur der winterlichen schneedecke als moglicher indikator fur die verbreitung von permafrost in den alpen. z. gletscherkd. glazialgeol. 9(1 haeberli, w. & patzelt, g. 1982: permafrostkartierung im gebiet der hochebenkar-blockgletscher, obergurl, otztaler alpen. z . gletscherkd. glazialgeol. 18(2), 127-150. hagen, j . 0. & liestel, 0. 1990: long-term glacier mass balance investigations in svalbard 1950-88. ann. glaciol. 14, 102-106. hall, k. 1986: rock moisture content in the field and the laboratory and its relationship to mechanical weathering studies. earth processes landforms 11, 131-142. 2 ) . 221-227. hall, k. & hall, a. 1991: thermal gradients and rock weath ering at low temperatures: some simulation data. permafrost and periglacial processes 2 , 103-112. hallet, b. 1983: the breakdown of rock due to freezing: a theoretical model. in permafrost, fourth international con ference, proceedings. national academy press, washington, d.c. pp. 433-438. hallett, b., walder, j. s. & stubbs, c. w. 1991: weathering by segregation ice growth in microcracks at sustained sub zero temperatures: verification from an experimental study using acoustic emissions. permafrost and periglacial processes 2,28>300. hegbom, b. 1914: uber die geologische bedeutung des frostes. pp. 294-206 in sjbberg, h. (ed.): bulletin of the geological institution of the uniuersity of llpsala 12. hegvard, k. & sollid, j. l. 1988a: kystkart svalbard b4 bellsund 1 : 200,000 (printed map). published by geografisk institutt, universitetet i oslo and norsk polarinstitutt. oslo. hegvard, k. & sollid, j. l. 1988b: kystkart svalbard b5 ser kapp 1 : 200,000 (printed map). published by geografisk insti tutt, universitetet i oslo and norsk polarinstitutt, oslo. hegvard, k. & sollid, j. l. 1989: kystkart svalbard c4 edgedya 1 :200,000 (printed map). published by geografisk institutt, universitetet i oslo and norsk polarinstitutt, oslo. hegvard, k. & sollid, j . l. 1990: kystkart svalbard b3 storfjor den nord 1 :200,000 (printed map). published by geografisk institutt, universitetet i oslo and norsk polarinstitutt, oslo. hegvard, k. & sollid, j. l. 1991: kystkart svalbard c3 olga stretet 1 : 200,000 (printed map). published by geografisk institutt, universitetet i oslo and norsk polarinstitutt, oslo. hegvard, k. & sollid, j. l. 1992: kystkart svalbard c2 hin lopenstretet 1:200,000 (printed map). published by geo grafisk institutt, universitetet i oslo and norsk polarinstitutt, oslo. king, l., gorbunov, a. p. & evin, m. 1992: prospecting and mapping of mountain permafrost and associated phenomena. permafrost periglacial processes 3 , 73-81. lautridou, j.-p. 1988: recent advances in cryogenic weath ering. pp. 33-47 in clark, m. j. (ed.): aduances in periglacial geomorphology. john wiley & sons, new york. lautridou, j.-p. & ozouf, j. c. 1982: experimental frost shat tering: 15 years of research at the centre de gco morphologie du cnrs. progress in physical geography 6 , 215-232. letavernier, g. and ozouf, j. c. 1987: la gtlifraction des roches et des parois calcaires. bulletin de i’association fran 5aaise pour i‘ktude du quarternaire 3 , 13%145. liestel, 0. 1988: the glaciers in the kongsfjorden area, spits bergen. norsk geogrofisk tidsskrifi 42, 231-238. mcgreevy, j . p. 1981: some perspectives on frost shattering. prop. phys. geogra. 5 , 5 6 7 5 . mcgreevy, j. p. & whalley, w. b. 1982: the geomorphic significance of rock temperature variations in cold environ ments: a discussion. arc. alp. res. 14(1). 157-162. mellor, m. 1973: mechanical properties of rock at low tem peratures. in north american contribution, permafrost, second international conference. national academy press, washington, d.c. pp. 334-344. nansen, f. 1922: the strandflat and isostasy. videmkapssel skapets skrifier. i . mat.-naturu. klasse. 1921. no. 11. 313 pp. 0degird, r., sollid, j. l. & trollvik, j. a. 1987: kystkart svalbard a3 forlandsundet 1 :ux),000 (printed map). pub lished by geografisk institutt, universitetet i oslo and norsk polarinstitutt, oslo. 106 r. s. odegbrd & j . l. sollid pmeghrd, r., sollid, j. l. & liestbl, 0. 1992: ground tem perature measurements in mountain permafrost, jotunhei men, southern norway. p e m f i o s t periglacial processes 3, 231-234. orvin, a. k. 1944: litt om kilder ph svalbard. nonk ceog. tidssk. 10(1), 24 pp. radd, f. j. & oertle, d. h. 1973: experimental pressure studies of frost heave mechanisms and the growth-fusion behavior of ice. in north american contribution, permafrost, second international conference. national academy press, washington, d.c. pp. 377-384. reusch, h. 1894 strandflaten, et nyt trak i norges geografi. norges geologiske vnders#gelse 14, 1-14. walder, j. s. & hallet, b. 1986: the physical basis of frost weathering: toward a more fundamental and unified per spective. arc. alp. re. 18.27-32. williams, p. j. & smith, m . w. 1989: thefrozen earth. cam bridge university press, cambridge. 306 pp. wiseman, wm. j., jr. & coleman, m. 1978: field trip report, noway and spitsbergen. louisiana state university, baton rouge, louisiana. mass balance and changes of surface slope, crevasse and flow pattern of erikbreen, northern spitsbergen: an application of a geographical information system (gis) bernd etzelmuller. g e l r vatne. rune s. b d e g a r d and johan ludvig sollid etzelmuller, b., vatne, g.. 0degard. r. & sollid, j. l. 1993: mass balance and change of surface slope, crevasse and flow pattern of erikhreen, northern spitsbergen: an application of a geographical information system (gis). polur reseurch 12(2), 131-146 the polythermal valley glacier erikbreen (79"40'n 12"30'e), northern spitsbergen, was investigated in 1970 and 1990 using digital photogrammetry and digital elevation model (dem) techniques. the bottom topography was derived from radio-echo soundings. based on the dem. mass balance and changes of surface slope, crevasse and flow pattern were evaluated, and internal ice deformation velocities were calculated. calculations of the total mass balance show that erikbreen has not been in equilibrium for the last 20 years. the average surface lowering was 0.38 m/a and the volume had decreaxd by 5% to 6 % from 1970 to 1990 or on the average by 3.5 x l v m ' a ' water. the glacier surface subsided over the whole glacier area except in minor areas with northfacing slopes in the accumulation area. the surface slope and the crevasse pattern. however. did not change significantly during the 20year-period, except in areas below 100 m a.s.1. eernd etzelmuller. geir vatne. rune s . 0degdrd & johan ludvig sollid. department of geography, university of oslo, p. 0. box 1042, n-0316 oslo, norway. introduction in the summers of 1990, 1991 and 1992 a gla ciological and hydrological monitoring program was established on the polythermal valley glacier erikbreen (79"40'n, 12"30'e, fig. 1) in the lief defjord area, svalbard (b@ 1992; vatne et al. 1992; odegird et al. 1992; etzelmuller et al. 1993; sollid et al. in press). the main aim of this work was to study the erosion, entrainment, transport and sedimentation processes within a highly gla ciated arctic drainage basin. this paper deals with further studies of the mass balance and the glacier dynamics as an input to investigations of the glacial material transport, the glacier front sedimentation processes and the subglacial drain age. vertical aerial photographs from 1970 and 1990 of the liefdefjord region were used for digital photogrammetric mapping of changes in the gla cier surface and crevasse pattern during the 20 year-period. subglacial topography of erikbreen was mapped in 1991 by radio-echo soundings (0deglrd et al. 1992). by combining these two information sources a digital elevation model (dem) of the glacier body was established for 1970 and 1990. total net mass balance over the period 1970 t o 1990 was calculated from the spa tial change of surface altitude. the glacier flow pattern was evaluated from the changes in the surface slope and the crevasse pattern, and ice deformation velocities were calculated for both years. mass balance data and calculated deform ation velocities were compared with field measurements. setting erikbreen has an area of 9 km2 and an average depth of 140 m. the maximum measured depth is 270 m, which is found in the accumulation area (0degird et al. 1992). the surface is heavily crevassed. erikbreen has a large accumulation area which is drained through a narrow and steep channel. this causes high surface velocities in the ablation area. the measured maximum velocity of 45 m/a was determined downglacier from the equilibrium line altitude. at the glacier front the velocity was 20m/a. erikbreen has a thermal structure of two layers, with an upper cold layer 132 b. etzelmiiller et al. fig. 1. the liefdefjorden area, northern spitsbergen. ( 1 ) ny-alsund; (2) longyearbyen. and a temperate layer at the sole. the thickness of the cold surface layer was approximately 20% 50% of the glacier thickness measured at the centre flow line ( 0 d e g l r d et al. 1992). the mass balance of erikbreen was positive in the balance year 1990/91, the equilibrium line being at 340 m a d . (etzelmuller et al. 1993). between the present glacier front and an arc of ice-cored moraines, a lake was dammed at a level of 10 m a.s.1. (in 1992). the depth of this lake varied between 10 m and 36 m (in 1990), being deepest near the glacier terminus. the nearest weather station is located in ny h e s u n d , approximately 80 km south of lief defjorden (fig. l ) , where a mean air temperature of -6.2"c and a mean annual precipitation of 372 mm has been recorded (hanssen-bauer et al. 1990). spitsbergen has continuous permafrost t o 400 m depth (liestd 1977). methods, error estimation and modelling work scheme this study consists of three main steps (fig. 2): (1) field surveying and photogrammetric work the digitizing of base topographic maps and crev asse pattern maps of erikbreen from 1970 and mass balance and changes of surface slope 133 angulation was used for absolute orienting of neighbouring stereospecific models and the 1970 air-photographs-series. therefore, mean errors were markedly higher than for the first 1990 model pair (table l ) , but accuracy of less than one metre was usually achieved in all axial directions. five metre contour lines could be digitized from the glacier surface (fig. 3) at this level of accuracy. however, parts of the accumulation areas on the s90-series could not be constructed because of snow fall just before photographing (covering ca. 30% of the glacier area) which made contouring impossible. the resulting topographic maps were converted in a triangle irregular network (tin) for rclief representation (cf. burrough 1986) and trans ferred into a high resolution grid with a five-metre cell size. the accuracy of the s90 derived dem was tested by comparing dem-derived altitudes, with actual values measured in the field two days before air photographing. different mean errors were obtained for the ablation and accumulation area because of fresh snow over part of the accumulation area and shadow effects in the infra red pictures. in parts of the ablation area (below 310 m a.s.1.) a mean error of less than 1.2 m was obtained (number of points = 25), increasing to 3 m in the areas above 350 m (number of points = 6). 1. i digital photogrammetry i i radlwcho sounding i inprl p ~ a m l w lor 111. deformation velocity model fig. 2 . work scheme for this study based on digital photo grammetry and radio-echo sounding. the three basis maps arc the crevasse pattern map. the topographic map and the interpolated map of glacier thickness ( i ) . based on these maps, glacier surface analyses were performed (11). which partly resulted in input parameters for an ice deformation velocity model ( 1 1 1 ) . dtm = digital terrain model. 1990; (2) analysis of topographic maps and creu asse pattern the analysis of changes in surface altitude, slope and crevasse pattern; (3) cal culation of basal shear stress and ice deformation uelocity the evaluation of changes in glacier flow. the base map construction and errors construction of the maps was carried out using a stereo plotter (wild a7) equipped with digital encoders. on the stereospecific model s90-6566, the standard deviation of accuracy was computed from field measured signal points and prominent points in the moraine area (table 1). aerial tri cis analysis glacier surface analysis. the basic information for the gis analysis consisted of the two raster based altitude grids from 1970 and 1990 and the digitized radio-echo profiles. the raster-gis module grid in the software package arc/ info (0 esri) was used for digital analysis. the grid-system is based on dana tomlin’s (1990) conceptional syntax and allows arithmetic, focal and zonal combinations between grids on a t a b k 1 . accuracy of registration from air photos. mean errors are in metres. model model n r . ( i ) sln) s90 s70 s70 s70 s70 s70 6566 6565 2296 2297 2298 2334 2333 model nr. (2) 6565 6564 2297 2298 2299 2333 2332 no. gcps s . 0.304 1.270 0.713 0.807 0.414 0.641 1.002 sy 0.050 0.743 1.270 0.820 0.401 0.668 0.849 mil 0.020 1.779 0.397 0.653 0.589 0.390 0.730 0. i95 1.295 0.885 0.771 0.469 0.600 0.879 134 b . etzelmiiller et al. fig. 3. topographic surface maps of erikbreen from 1970 and 1990. parts of the accumulation area were not mapped in 1990 due to snow fall just prior to air photographing. mass balance and changes of surface slope 135 pseudo-node. crevasse directions (in degrees clockwise from north) were calculated by using the coordinates of the nodes, which define the lines. the direction of the crevasses was therefore defined by a simple line although the crevasses in reality were curved. the lengths of single crev asses were not taken into consideration in the calculations. mean direction ( e ) , resultant r and stan dardized resultant r , ( r divided by number of observations n) were computed applying the fol lowing equations (mardia 1972): cell by cell basis. the noise in the altitude grids was removed by a mean filter with 50 m kernel width. the average volume change (av,) for a given elevation interval, j , of the glacier in m3 of ice and the average net balance ( b , ) in metres of water was determined as: n av, = 8 z (h1970 h 1 5 9 1 ) ) (1) 1 ' 1 where h i s the surface altitude in rn ( i n years 1970 and 1990), d is the cell resolution in metres, aaj is the glacier surface area in the elevation j , pice is the ice density in kgm-', pn, is the density of water (1000 kg m-3) and n is the total number of cells for a given elevation interval. the ice-density was set to pice = 900 kg m-3 for the whole glacier. the change of the equilibrium line altitude during the study period has been neglected. the net balance ( v ) of the whole glacier was obtained as ( 3 ) where rn is the total number of elevation intervals on the glacier (given as m3 of water) based on the altitude grids the glacier surface slope (g) was calculated, where z is the surface altitude and x and yare the coordinate axes in the horizontal plane (cf. burrough 1986; skidmore 1989; zevenbergen & thorne 1987). the change of slope (ag) between 1970 (gl97") and 1990 (giyyo) was computed as: ag = gi970 gly90 the dependence of surface lowering upon sur face altitude and slope angle was analysed by applying zonal statistics in altitude or slope inter vals. graphs used in the text are automatically sampled from grids along pre-defined profile lines. ( 5 ) crevasse pattern analysis. the crevasse pattern was analysed by using the vector-based part of the a r c ~ n f o software pz rge. crevasses were digitized as lines which start and end with a i = i r = d m (7) to test differences in mean direction and the concentration parameter k of two subsamples, f tests (mardia 1972) were applied on each sub sample pair from 1970 and 1990. calculation of shear stress and ice deformation oelocity. the basal shear stress and the ice deformation velocity for parts of the glacier area were calculated using the grid system. the basal shear stress and internal ice deformation velocity was computed from the surface slope and depth of a glacier, using nye's (1952) model: where ud is ice deformation velocity, us and u b are surface and basal velocities, respectively, a and n are constants from glen's (1955) flow law for ice, h is glacier thickness and tb is the basal shear stress: tb = f p g h sin a ( 9 ) where f is a form factor (nye 1965), p is the density of the glacier, g is the acceleration of gravity and a is the glacier surface slope. for erikbreen, ice at the bed was assumed temperate (odegird et al. 1992). the constants of the flow law were set to n = 3 and a = 1.67 x a-' kpa-3 (paterson 1981). the variable par ameters were the glacier thickness ( h ) , the surface slope gradient ( a ) and the form factor (f). glacier thickness interpolation was based on 136 b. etzelmiiller et al. fig. 4. map of ice thickness. the equidistance of the contour lines is 40m. the map is interpolated by a third order inverse distance weighting based o n radio-echo-sounding (0degard et al. 1992). digitized radio-echo profiles ( 8 d e g i r d et al. 1992, fig. 4) and altitudes of the glacier's edge. the sounding lines were not significantly dense to make a good model of the subglacial topography, particularly in the ablation area. estimates could, however, be made using data along the centre flow line of the glacier. a 50-m-cell-sized grid was computed representing glacier thickness in 1990. glacier thickness in 1970 was computed by adding the computed altitude change to the glacier thick ness data from 1990. a discussion of interpolation procedures of linear profile data is given else where (bjornsson 1988; herzfelt & holmlund 1988; eriksen et al. 1993; etzelmiiller unpubl. data). a third order inverse distance weighting interpolation was used in calculations presented in this paper (fig. 4). when applying nye's (1952) ice sheet model for ice-sheets and large valley glaciers (cf. bind schadler et al. 1977; paterson 1981), surface slope should be averaged over a surface length of 8 to 16 times the glacier depth. to compute slope averages on erikbreen, low pass filtering tech niques were used on the slope map, following the general equation m n r ( i , j ) = e e @ ( m y n ) t ( m , n ) (10) where @ is the slope in a given cell, t is a kernel with size m x n and r is the smoothed slope value. to avoid smoothing in all directions, win dow kernels taking the principle direction of the glacier channel into account (appr. 150" clockwise from north) were applied on the slope grids. the kernel size could be varied between 300m and 1000 m slope length averaging. a kernel which averaged slope over a surface length of 1ooom was used for calculations presented in this paper (fig. 5). the f-factor was derived for a parabolic channel cross-section from nye's (1965) tables after calculation of the geometrical parameter m = l n = l width 2 x depth' w = in the accumulation area the f-factor usually was 1. a grid containing values of w was calculated from a grid which contained information of zones with equal glacier width and the grid of glacier thickness. mass balance and changes of surface slope 137 fig. s. upper: surface slope calculatcd from 1970 glacier. lower: smoothed surface slopc from the 1970 glacier. the smoothing was carried out using a convolution kernel which smoothed the values over a distance of loo0 m. results ranged from over 35 m (>1.8 m/a) in the lower comparisons of the glacier surface in 1990 and 1970 the area of the glacier erikbreen decreased by 8.1% (0.79 km2) from 1970 to 1990. retreat at the glacier front accounted for 40% of this reduction. as only 63% of the 1990 glacier surface could be mapped, calculations of changes in surface altitude over the whole glacier were not possible (fig. 6). in the mapped area the mean surface altitude decreased by 11 m (0.55 m/a). the values ablation area, to 5-15 m (0.3-0.7 m/a) at the equi librium line area (figs. 6, 7 and 8). in the area which lacks photogrammetric altitude data for 1990, a surface lowering of between 0 and 3 m was obtained by comparing geodetic measured surface altitude points along the centre flow line of the glacier with the 1970-altitude (number of points = 10). in the retreat area of the glacier front a minimum average surface lowering of 14 m (0.7 m/a) was obtained. assuming an average surface altitude lowering of 1 . 5 m over the 20 138 b . etzelrniiller et al. fig. 6. surface lowering o f erikbreen from 1970 to 1990. year-period in a part of the accumulation area, where 1990 altitude data were not obtained, the average surface lowering over the whole glacier area was estimated as 7.5 m (0.38 m/a) between 1970 and 1990. however, smaller areas with minor net mass gain are situated on northfacing slopes in part of the accumulation aiea (fig. 6). assuming a mean glacier depth of 140 m, the 1970 glacier volume was equivalent to approximately 1.25 x 10ym3 of water. suggesting an altitude change of 0.5 m/20a in the part of the accumu lation area, where 1990 altitude data were not obtained, the volume of melted ice over the entire glacier was in the order of 6.5 x lo7 m3 of water. for a suggested altitude change of 2.5 m/20a in the same area the mass loss was calculated to 7 x 107m3 of water, this represents a volume change of between 5% and 6% from 1970 to 1990. the annual mass loss therefore ranged from 3.2 x lo6 m3/a to 3.5 x lob m3/a of water. this gives an average annual specific discharge of 9 is-' km-* in the 20-year period due to the mass loss. a significant change in surface slope in the 20 year period could only be traced in the lowermost ablation area (fig. 9). crevasse pattern. in the ablation area the num ber of crevasses on erikbreen did not change significantly in the period of study (figs. 10 and 11). comparisons in the accumulation area were difficult to make due to fresh snow in 1990. field observations, however, indicate a similar crevasse pattern as in 1970. rayleigh's test (mardia 1972) of the stan dardized resultant (significance level = a0.,) indi cates a preferred orientation of all samples. the crevasse pattern at the piedmont-like glacier front below 100 rn a d . showed a minor difference in mean direction (fig. 11; table 2), but statistically mass balance and changes of surface slope 139 however, testing on mean direction (mardia 1972) at a significance-level = gave f-values lower than the critical value. in the lower accumu lation area no significant change in either direc tion or distribution was observed (table 2). 28 24 20 8 4 0 altitude change (in rn) fig. 7. histogram of the surface lowering. the histogram shows a multimodal distribution, with three peaks. using the his togram one can divide erikbreen into at least three areas of similar appearance: the flat accumulation area between 500 and 600 m a.s.1. (altitude change m m ) , the intermediate areas between 250 and 500 m a.s.1. (altitude change 8-15 m), and the lowermost ablation area below 250 m a.s.1. (altitude change >20 m), peak (1) represents altitude change in the accumulation area and would be higher if the whole glacier had been mapped. peak (2) displays the average range of surface change in the ablation and lower accumulation area, while peak (3) represents the high surface changes in the lower ablation area. significant differences in spread values r. the test on the concentration parameter (k) gave a significant change at significance level = (table 2). this area had a surface lowering of >25% i n relation to 1970 glacier depth along the centre flow line. in the area between 100 and 400 m a.s.1. the crevasse pattern is more uniform with r,-values of near 0.9 for both years. altitude (ma.s.1.) net mass balance am dlstrlbutlon (m120a of water) i (in km2) fig. 8. mass balance of erikbreen in the period 1970-90. estimated basal shear stress and deformation velocity calculated basal shear stresses and ice deform ation velocities in the centre flow line of erikbreen ranged between 0.6-1.6 bar and 1-40 m/a, respectively. highest values were obtained at the glacier falls between stake 7 and stake 8 (fig. 12). the relative change of calculated ice deform ation velocity during the 20 year period was cal culated as the ratio r = . in the glacier area above 100 m a.s.1. r oscillates between 0.2 and 0.3, and r increases below 100ma.s.l. at the glacier terminus nye’s (1952) model is not applicable. y1970 v1990 v1970 comparison with field measurements mass balance. on erikbreen, mass balance measurements have been carried out during two balance years, 1990191 and 1991192. in the bal ance year 1990191 the glacier had a weak positive mass balance (0.14 m) (etzelmiiller et al. 1992) while in 1991192 the balance was zero to slightly negative. the average summer balance in the period 1990-92 ranged from -2m/a in the ablation area to -0.4 m/a in the accumulation area (table 3). the annual altitude decrease at erikbreen in the period 1970-90, at stakes pos itioned at the centre flow line of the glacier, was half or less of the average summer balance in 1990-92 (table 3). if the average summer balance in 1990-92 was a reasonable estimate for the 20 year period, 50% of the surface lowering would have been compensated by ice flow in the ablation area. water balance. the water balance of erikbreen was measured during the summers from 1990 to 1992 (vatne et al. 1992; table 4). the monitoring program did not cover the entire melting season. discharge measurements carried out on the south shore of liefdefjorden in 1990, 1991 and 1992 for the period mayijune to the end of august (barsch et al. 1992) and in the river bayelva (a meltwater river from austre and vestre br~ggerbreen 140 b . etzelmuller et al. 450-500 400-450 350-400 300-350 250-300 200-250 150-200 100-1 50 50-1 00 25-50 0-25 ititudes, m -0.6 -5 0 5 10 15 slope (in degree) fig. 9. differences of slope in 1970 and 1990 in relation to altitude. the values are averaged over the altitude levels. significant changes are only measured below 100 m a d . where changes are > l o % change in relation to 1970 slope. glacier) in the vicinity of ny-alesund (carried out by norges vassdragsog energiverk, nve) indicate that the specific meltwater discharge from erikbreen was higher than measured in 1990 to 1992 by a factor of 1.5 (for 1991) to 2 (for 1990 and 1992). this gives a specific discharge estimate of 1540 i s ' km-* from erikbreen in 1990 to 1992 (table 4). table 2. crevasse pattern analysis statistical moments and tests. the roman numerals refer to area codes used in figs. 10 and 11. area i (below area i1 (1w area 111 ( 3 w 100 m a d ) 300 m a.s.1.) 500 m a.s.1.) 1970 1990 1970 1990 1970 1990 @ r, k 145.3 154.0 71.6 61.1 47.6 43.2 0.74 0.90 0.91 0.90 0.85 0.86 2.289 5.305 5.852 5.305 3.68 3.91 two sample fl,n.2 = 0.43 tests (on @) = 2.71 two sample fnl.,,n,.l = 2.03 tests (on k ) ~ y a . 0 1 = 1.86 fl.n.2 = 0.53 = 2.71 mass balance and changes of surjace slope 141 i fig. 10. crevasse pattern of erikbreen in 1970 and 1990. the roman numerals refer to area codes used in fig. 1 1 and table 2. 142 b. etzelmiiller et al. 303 j. "t 'lgo 303 1 1970 3 0 3 t n 160 30% a 5 0 , n 3 4 5 # fig. 11. crevasse direction roses for erikbreen in 1970 and 1990. the arrows indicate the principle mean direction of the crevasses. n denotes the number of crevasses used in the analy sis. the lower crevasse density measured north and west of the nunatak is due to snowfall covering crevasses in 1990. surface velocity. -surface velocities on erikbreen were measured in 1990, 1991 and 1992 at 10 stakes along the centre flow line of the glacier (etzelmiiller et al. 1993). the measured velocities were partly much higher than the calculated deformation velocities, indicating an increase of the basal sliding component downglacier (fig. 12). discussion total mass balance the surface altitude change data showed that erikbreen had an average decrease of 7.5m (38cm/a) for the last 20 years. this is in good accordance with data from austre br~ggerbreen and midre lovtnbreen in the vicinity of ny alesund. surface lowering of 8.9 m (42 cm/a) on austre br0ggerbreen and 7.5 m (36 cm/a) on midre lovcnbreen was calculated for the period 1967 to 1988, based on annual mass balance measurements (hagen & liest01 1990). like other glaciers on spitsbergen (hagen & liest01 1990), erikbreen was not in climatic equilibrium, and due to the volume reduction water drained from the glacier in excess to that of an equilibrium state. discharge measurements for erikbreen table 3. measured net and summer balance at stake 1 to 10. all values are water equivalent. summer balance consists of mean values from the period 1990-1992 no. (ma.s.1.) net balance summer balance (m/a) mean altitude change 197cl90 (m/a) 1(17) 2 (14) 3 (68) 4 (133) 5 (203) 6 (311) 7 (370) 8 (487) 9 (536) 10 (598) -1.16 (90/91) 1.39 (90/91) -1.83 (90/91) -1.00 (90/91) -0.37 (90/91) -0.70 (91/92) -0.12 (90/91) -0.46 (91/92) +0.05 (90/91) +0.03 (91/92) +0.55 (90/91) +0.27 (91/92) +0.61 (90/91) +0.36 (91/92) +0.54 (90/91) +0.29 (91/92) -2.04 -1.94 1.67 -1.69 -1.22 -1.17 1.08 -0.73 -0.48 -0.48 1 . 1 -1.2 -1.1 -0.8 -0.6 -0.5 -0.6 -0.6 1 0 . 1 5 0 . 2 mass balance and changes of surface slope 143 .. 4030 20 120 00 10 40 calculated ice dolormation vdodty (wa) ulajated bupl show rkou (kpa) a ' 6 o ; & \ \ distance doqlacier (in km) calculatedhneaswed velodty dstpn, (km) distance (km) fig. 12. results of the calculation of ice deformation velocity. all data displayed in the graphs are sampled along the centre flow line of erikbreen. a . calculated ice deformation velocity. the dots denote measured surface velocity at the centre flow line of the glacier (in m/a). b. calculated basal shear stress (in kpa). solid line represents the 1970 glacier; dashed line represents the 1990 glacier. these values are computed for a parabolic cross profile and slope averaging over 1ooom. c. ratio calculated/ measured velocity. the line-shaded area ( a ) indicates the deformation component of the measured surface velocity. while the cross-shaded area (b) indicates the basal sliding component. i n the accumulation area the ratio is near i , decreasing to below 0.2 in the lowermost ablation area. this shows increased basal sliding downglacier. indicated that specific runoff in a year with zero net mass balance was in the range 15-20 is-' km-2 (table 4). water supplied from the reduction in volume of the elacier could be estimated in the the long-term runoff was estimated to be 30% higher than it would be under zero net balance conditions. range 2 is-' kmr2 to 20 is-' km-2 or 10%-50% of the total runoff in 1992 and 1990. in 1990 ablation development of glacier flow was extremely high. these values seem com parable to data reported from austre brag gerbreen (hagen & lefauconnier 1992) where an important question is how the thinning of erikbreen affected the glacier flow. liestd (1969, 1988, 1989) suggested that most of the svalbard table 4. discharge measurements on erikbreen. specific discharge (in is-' km-*) total estimated total over year period (in 106m3) period year one year 1990 11 july-28 august 8.3 169.0 21.3 ca. 40 1991 1 july-14 august 3.4 83.6 10.1 ca. 15 1992 12 july-18 august 4.4 118-0 117.0 ca. 22 measurement discharge measurement over the 144 b . etzelmiiller et al. glaciers are of a surge type. observations and measurements show that these glaciers are not able to maintain balance velocity at the equi librium line altitude. this will result in a steeper surface profile as observed and described for hessbreen, finsterwalderbreen (liest01 1969), usherbreen (hagen 1987), austre br~ggerbreen and midre lovhbreen (hagen & l i e s t ~ l 1990). the results presented here indicate that steep ening of the glacier surface at the equilibrium line altitude is not the case for erikbreen during the study period. as the numbers of crevasses have not changed significantly over the 20 year period, it is assumed that the general flow pattern had not changed much. in the area above 100 m a.s.l., basal shear stress was calculated to be 10% higher on average, and deformation velocity 20%-30% higher in 1970 than in 1990. the thinning of the glacier did not cause a significant increase of surface slope. therefore, higher surface velocities could be expected in 1970 under the condition of un changed thermal regime. in the areas below 100 m a.s.l., where mass loss caused a more than 25% reduction of glacier thickness since 1970, surface slope increased and the crevasse pattern changed significantly. how ever, in the area below 25 m a d . the glacier surface slope decreased. in the area between 25 m a.s.1. and 100 m a d . , computed shear stress and deformation velocity had not changed in relation to 1970 (fig. 12). in the areas below 25 m a.s.1. shear stress and deformation velocity were assumed to be nearly zero in 1990. however, in the same year high velocities of 20m/a were measured, which clearly showed the influence of buoyancy forces from the lake, inducing high sliding rates. the present glacier flow pattern the calculations and field measurements indi cated that the present glacier flow pattern is dom inated by an increasing basal sliding component downglacier in the ablation area of erikbreen, which causes high surface velocities. several explanations or combinations of these may be advocated: (a) subglacial drainage system and (b) deforming subglacial till. (a) erikbreen is highly crevassed in the ablation area. hence, meltwater reaches the glacier bed at many locations. to collect these streams a high order dendritic system may be present as indicated by tracer studies carried out on erikbreen in 1990 and 1991 (vatne unpubl. data). as the melt rate is highest in the lower part of the ablation area, the meltwater would lubricate the bed most effectively in this area. (b) fine-grained till under erikbreen has been observed in the glacier portal and the con centration and grain-size distribution of sus pended sediments (vatne et al. 1992) indicate that this layer extends some distance upglacier from the terminus. if subglacial till is present beneath parts of the glacier, it will be water satu rated because of temperate conditions (0degbrd et al. 1992). during subglacial transport, clasts are comminuted, leading to reduction of the mean grain-size along the transport path (dreimanis & vagners 1971). therefore, the subglacial till may be most fine-grained in the lower ablation area. fine-grained subglacial till will have low shear strength and be more easily deformable (boulton et al. 1974; boulton & hindmarsh 1987; clarke 1987). deforming subglacial till may therefore contribute substantially to the glacier flow velocity in the lower part of the glacier. dynamic equilibrium dynamic equilibrium means that the glacier maintains the balance velocity at the equilibrium line altitude. rough estimations published in etzelmiiller et al. (1993) indicate that erikbreen maintained balance velocity during 1990/91. based on the following observations it was con cluded that erikbreen did not develop a dynamically unstable length profile from 1970 to 1990: 1. surface lowering was observed in the accumu lation area. 2. the velocity pattern did not change signifi cantly. 3. the surface slope had not changed significantly above 100 m a.s.1. 4. the apparent high basal sliding rates in the ablation area maintained a high ice flux down glacier. digital techniques glaciological studies traditionally have used ana log terrestrial and air-photographically based photogrammetric measurements to map glacier surface changes (cf. hoinkes 1970; brunner & rentsch 1972; finsterwalder & rentsch 1976; mass balance and changes of surface slope 145 ing high basal sliding velocities due to buoyancy forces. the crevasse pattern changed significantly only in areas below 100 m a d . measured surface velocities increased downglacier due to high basal sliding, which ensured high ice fluxes; thus erikbreen did not develop an unstable surface profile in the period 1970-1990: the combination of digital analysis of photo grammetric and radio-echo data provides a powerful tool for describing glaciers. the digital techniques can be carried out with commercial software, opening the potential for glacier surface analysis at a regional scale with the objectives of describing climatic dynamical changes of glaciers. the use of dems in glacier studies and modelling has been further emphasized by this study. acknowledgements. t h e field work for the study of erikbreen was carried out in connection with the german-led project “stofftransporte land-meer in polaren geosystemen” which was initiated by “arbeitskreis fur polargeographie” and finan cially supported by the “deutsche forschungsgemeinschaft” (dfg). the project was coordinated by w. d. blumel. uni versity in stuttgart. from the university of oslo, 0. liestdl gave constructive advice for the study. 1. berthling. p. h . bd and l. langkaas took part in the field work and k. melvold and t . tonning did the photogrammetric mapping. two anonymous reviewers improved the manuscript considerably. the authors received financial support from the deutsche forschungsgemeinschaft (dfg). the norwegian national com mittee for hydrology (nhk). the norwegian polar institute and the polar committee of the faculty of science at the university of oslo. the authors would like t o thank all persons and institutions mentioned above. all analysis presented in the paper were compiled at the laboratory for remote sensing, thematic mapping and gis at the department of geography, university of oslo. finsterwalder 1978; lipert 1987; rentsch et al. 1990) and to measure glacier surface flow (cf. finsterwalder 1931; voigt 1966, 1967; melvold 1992). with the recent development of powerful computer softand hardware, such data can be extracted and analysed digitally. this applies to dem analysis of digital maps of a glacier body or differential surfaces and standardized analysis of glacier surface changes in time (cf. peipe et al. 1978; rentsch et al. 1990; lundstrom et al. 1993). additionally, derivates of the dem analysis may be used to calculate glaciological variables, such as changes in ice deformation velocity or basal shear stress. conventional gis-software can be used in comparative studies of glaciers on a regional scale, concerning studies of the climatic impact on glacier mass balance and glacier dynamics. changes in the glacier surface slope and the crevasse pattern have been used to explain changing dynamic behaviour of glaciers (lefau connier & hagen 1991). using dem, theoretical calculations of the subglacial drainage pattern are possible (cf. b j ~ r n s s o n 1988). digital techniques, however, require knowledge of the accuracies of the sampled data. this is especially important when using interpolation procedures, particularly when not applying objective geostatistical methods as kriging for interpolation (cf. bur rough 1986). however, the combination of dem based photogrammetric measurements and radio echo soundings integrated in a geographical infor mation system (gis) will become more important in the future for analysing glaciological data. conclusions the mass balance of erikbreen was negative dur ing the period 1970 to 1990. the same applies for other glaciers on svalbard where long term mass balance measurements exist (hagen & liest01 1990; lefauconnier & hagen 1990). due to the mass loss of the glacier, the annual long-term runoffwas at least 10%-20% higher than it would have been under equilibrium mass balance con ditions. this effect might be decreasing as mass balance approaches zero on glaciers in svalbard (hagen & lefauconnier 1992). in the area above 100 m a.s.1. the deformation velocity seems to have been reduced in the period of study. however, the thinning of the glacier did not cause a marked increase of glacier surface slope. in the glacier front zone, a moraine-dam med lake influenced glacier front dynamics, caus references barsch. d., gude. m., mausbacher, r., schukraft. g. & schulte, a. 1992: untersuchungen zur aktuellen fluvialen dynamik im bereich des liefdefjorden in nw-spitsbergen. stungarter geographische studien 11 7. 217-252. bindschalder, r., harrison, w. d., raymond, c. f. & crosson, r. 1977: geometry and dynamics of a surgc-type glacier. j . glaciol. 18 (79), 181-194. bjornsson, h., 1988: hydrology of ice caps in volcanic regionr. societas scientarium islandica. university of iceland. reyk javik. 139 pp. boulton, g. s., dent, d. l. & morris, e. m. 1974: subglacial shearing and crushing, and the role of water pressures in tills from south-east iceland. geogr. ann 56a (3-4). 135145. boulton, g. s. & hindmarsh, r . c. a . 1987: sediment deform ation beneath glaciers; rheology and geological conse quences. 1. geophys. res. 92, 9052-9082. 146 b . etzelmiiller et al. burrough, p. a . 1986: principles of geographical information system for land resources assessment. monographs on soils and resources survey no. 12, clarendon press, oxford. 194 pp. brunner, k. & rentsch, h. 1972: die anderung von rache, hdhe und volumen am vernagtund guslarferner von 1889 1912-1938-1969. z . gletscherd und glazialgeol. 8 , 11-25. be, p. h. 1992: materialtransport i midtdalsbreen, s)r-noreg, og vestre lovtnbreen og erikbreen, svalbard. unpubl. cand. scient. thesis, department of physical geography, university clarke, g. k. c. 1987: subglacial till: a physical framework for its properties and processes. journal of geophysical research 92, 9023-9036. dreimanis, a. & vagner, j. j. 1971: bimodal distribution of rock and mineral fragments in basal tills, pp. 237-250 in goldthwait (ed.): till: a symposium. ohio state university press. eriksen, m. g., bjornsson. h., herzfeld, u. c. & holmlund, p. 1993: the bottom topography of storglaciaren. nat urgeograjiska institutionen, forskningsrapport 95. 34 etzelmiiller, b., vatne, g., bdegard, r. s. & sollid, j. l. 1993: dynamics of two subpolar valley glaciers, erikbreen and hannabreen, liefdefjorden. northern spitsbergen. geogr. ann. 75a (1-2). 41-54. finstewalder, r. 1931: geschwindigkeitsmessungen an gletscher mittels photogrammetrie. z . glerscherkd. gla zialgeol. 19. 251-262. finstenvalder, r. 1978: beitrage zur gepatschfernervermes sung. 2. gletscherkd. glazialgeol. 14, 153159. finstewalder, r. & rentsch. h. 1976: die erfassung der hohenanderung von ostalpengletschern in den zeitriumen 1950-1959-1969. z . gletscherkd. glazialgeol. 12, 29-35. glen, j. w. 1955: the creep of polycrystalline ice. proceedings royal society series (london) a 238, 519-538. hagen, j. 0. 1987: glacier surge at usherbreen, svalbard. polar research 5. 239-252. hagen, j. 0. & leistel. 0. 1990: long term glacier mass balance investigations in svalbard, 1950-88. ann. glaciol. hagen, j. 0. & lefauconnier, b. 1992: rcconstructed runoff from the high arctic basin bayelva in svalbard based on mass-balance measurements. pp. 155168 in prowse, c. s. 1. & ulmer, k. e. (eds): proceedings, 9lh international north ern research basins symposium1 workshop, canada. nhrl symposium no. 10. hanssen-bauer, i . , kristenscn solps, m. & steffensen, e. l. 1990: the climate of spitsbergen. the norwegian meteoro logical institute, report no. 39/90. 40 pp. herzfelt, u. c . & holmlund, p. 1988: geostatistical analysis of radio-echo data from scharffenbergbotnen, dronning maud land, east antarctica. z. gletscherkd. glazialgeol. 24, 95 110. hoinkes. h. 1970 methoden und moglichkeiten von mas senhaushaltsstudien auf gletschern. 2. gletscherkd. gla rialgeol. 6. 38-85. lefauconnier, b. & hagen. j. 0. 1990: glaciers and climate in svalbard; statistical analysis and reconstruction of the breggerbrccn mass-balance for the last 77 years. ann. claciol. 14, 148-152. lefauconnier, b. & hagen, j . 0. 1991: surging and calving of oslo. 83 pp. pp. + app. 14, 102-106. glaciers in eastern svalbard. norsk polarinst. medd. nr. 116. 130 pp. leistd, 0.. 1969: glacier surges in west spitsbergen. can. 1. earth sci. 6 ( 4 ) . 895-897. liestel, 0. 1977: pingos, springs and permafrost. norsk pola rimt. arbok 1975, 7-25. liestel, 0 . 1988: the glaciers on the kongsfjorden area. norsk geograf. tidsskr. 42 (4), 231-238. liestel, 0. 1989 kompendium i glasiologi. meddelelser fra geografisk institutt. universitetet i oslo. naturgeografisk serie, rapport nr. i s . oslo. 87 pp. lipert, c. 1987: photogrammetric works in the werenskiold glacier area, spitsbergen. polish polar res. 8 , 47-55. lundstrom, s . c., mccafferty, a. e . & coe, j. a. 1993: photogrammetric analysis of 198489 surface altitude change of the partially debris-covered eliot glacier, mount hood, oregon, u.s.a. ann. glaciol. 17, 167-170. mardia, k. v. 1972: statistics of directional data. academic press, london. 357 pp. melvold, k. 1992: studie av brebevegelse pp kongsvegen og kronebreen, spitsbergen. meddelelser fra geografisk insti tutt, universitetet i oslo. rapportserie i naturgeografi. rap port nr. 1. 60 pp i app. nye, j. f. 1952: the mechanics of glacier flow. j . glaciol 2 nye, j . f. 1965: the flow of a glacier in a channel of rectangular, elliptic or parabolic cross-section. j. giaciol5, 661-690. bdegard, r . , hamran, s. e., b e , p . h., etzelmiiller, b., vatne, g . & sollid, j. l. 1992: thermal regime of a valley glacier, erikbreen. northern spitsbergen. polar res. 11 (2). 69-80. paterson, w. s. b . 1981: the physics of glaciers. pergamon press. oxford. 378 pp. peipe, j., reiss, p. & rentsch, h. 1978: zur anwendung des digitalen gelandemodells in der gletscherforschung. z . glerscherkd. glazialgeol. 14, 161-172. rensch, h . , welsch, w., heipke, c. & miller, m. m. 1990: digital terrain models as a tool for glacier studies. 1. glaciol. 36. 273-278. skidmore, a. k. 1989: a comparison of techniques for cal culating gradient and aspect from a gridded digital elevation model. internat. 1. geograph. infor. sys. 3 (4). 323334. sollid, j. l., etzelmiiller, b., vatnc, g . & bdegprd, r. s. in press. glacial dynamics, material transfer and sedimentation of erikbreen and hannabreen, liefdefjorden, northern spits bergen. zeitschrift fur geomorphologie, suppl. band. tomlin, dana c . 1990. geographic information s y s t e m and cartoraphic modeling. prentice hall, n.j. 246 pp. vatne, g . , etzelmiiller, b . , bdegsard, r. & sollid. j. l., 1992: water-budget and glaciofluvial sediment transfer of a subpolar glacier, erikbreen. svalbard. stutrgarter geo graphische studien 117, 25f267. voigt, u. 1966: the determination of the direction of movement on glaciers surface by terrestrial photogrammetry. j . glaciol. 6. 359-367. voigt, u. 1967: ergebnisse dcr bewegungsmessungen an kongsvegen und kronebreen. geodarische und geogra phische veroffentlichungen, reihe ill. heft 9. 70-98. berlin. zevenbergen, l. w. & thornc, c . r. 1987: oudntitative analy sis of land surface topography. earth surface processes and landform 12, 47-56. (26), 82-93. small mammals from the koren arctic expedition to the kolyma river, northeast siberia 1914-1918 fridtjof mehlum and eugene potapov mehlum, f. & potapov, e . , 1995: small mammals from the koren arctic expedition t o the kolyma river. northeast siberia 1914-1918. polar research 14(1), 1-14. a small mammal collection from the kolyma region in northeastern siberia collected by the norwegian trapper and naturalist johan koren between 1915 and 1917 comprises 152 specimens of 17 species. the collection was brought t o norway with roald amundsen’s “maud” expedition through the northeast passage and has been held by the zoological museum, university of oslo. when comparing the collection with the current distribution of small mammals in the region, it is not possible to detect changes in the small mammal fauna. as several species which are common today are missing in the collection, the collection apparently does not give a complete account of the small mammal fauna in the kolyma region from 1915 to 1917. this discrepancy can largely be explained by the fact that koren caught small mammals only in parts of the kolyma region and not in those areas where the missing species are found in abundance. f. mehlum, norwegian polar institute, p . o . box 5072 majorstua, n-0301 oslo, norwav; e . potapou, uppsala uniuersity, department of zoology, villawagen 9, s-752 36. uppsala. sweden. introduction the norwegian field naturalist and trapper johan koren made five expeditions to northeastern si beria during the period 1908-1918. he made two expeditions to the lower kolyma region. after the first of these, with his own schooner “kitti wake” (1911-1912) he returned with an impress ive collection of bird and mammal specimens from an area which had been visited by very few zool ogists. the bird collection was treated by the sponsor of the expedition j. e. thayer (thayer & bangs 1914), and the mammal collection was processed by allen (1914). allen described eight new species and subspecies of mammals, and the entire collection (including the types) was donated to the museum of comparative zoology, cambridge, massachusetts. the area of the kolyma lowlands made such a deep impression on koren that he returned and settled there in 1914. on his journey to the lower kolyma in 1914 he was accompanied by seven other participants, among whom were zoologist copley amory. jr., geologist benns alexander, and john wyckoff, who made motion pictures during his stay (schaanning 1920; evjenth 1938). for russian names and literature references in norsk polar insritutf’s publications, the international bibliographic tran scription “scando-slauica” is w e d which corresponds with the i s 0 (international standard organization) transcription. the schooner “eagle”, which carried the expedition, was drawn up on land, and the par ticipants moved into two log cabins hiredin niine kolymsk. from here they made several excursions to the surrounding areas. during his residential period from 1914 to 1918 in niinekolymsk (near the recent kolymskoe settlement), koren collected a large number of birds and mammals. after the outbreak of world war i, all the participants except koren returned to the united states in july 1915. copley amory, jr., had made a bird collection which was even tually examined by riley (1918). koren stayed in the area until summer 1917, at which time he made plans to travel to the united states to sell furs. he left his collections of birds and small mammals in niinekolymsk, and sailed with the steamer “kolyma” to vladivostok. however, because of the export prohibition on furs, he had to drop his plan to travel to the united states and instead chose to sell his furs in vladivostok (evjenth 1938). he was hired by the fur company “youroveta” and stayed in vladivostok until the spring of 1918 when h e returned t o the kolyma area to join a trapping expedition organised by the fur company. koren stayed in kolyma until the following autumn when he returned to vladi vostok via irkutsk. during the winter, after hav ing probably caught the spanish flu, he died in vladivostok on 3 march 1919 (schaanning 1920). 2 f. mehlum di e . potapoo during the expedition with the vessel “maud” through the northeast passage (191s1920). the norwegian polar explorer roald amundsen spent the winter 1919-1920 near the kolyma delta. h e r e he received information about koren’s col lections and sent his men t o the residence of koren’s widow in niinekolymsk in may 1920 (amundsen 1921). later the material was brought back t o norway and donated to the university of oslo. t h e present collection contains skins and skulls of small mammals collected by koren in the lower kolyma region in 1914-1918. koren’s col lection of skins and birds‘ eggs was examined by schaanning (1954). but the mammals collection has been unexamined until now. t h e collection is kept at the zoological museum, university of oslo. t h e aim of this paper is to draw attention to a valuable collection which has never been studied by zoologists. koren left n o notebooks on the collection. and none of the specimens were ident ified. fortunately. the skins and skulls were lab elled with information o n locality. date, sex, body length. tail length and hind foot length. small mammals in the lower kolyma were also studied by one of the present authors ( e . p . ) in 1982 1992. this then allowed us to compare the mam mals collected by koren with the current dis tribution of t h e animals. t h e information o n the localities where the specimens were taken includes few details. however, a survey of the current distribution of mammals in the region would give an indication of the localities where the mammals were collected. geographical description the river kolyma crosses the northern part of the magadan district and the northeastern part of the jakut (sacha) republic (fig. 1). it is 2.600 km long and flows from the kolyma mountains into the east siberian sea. the upstream part of the river is locked in the mountains. t h e water here is clean and the flow is very forceful and rapid. in the lower part of the river the water flow is slow: the river carries a lot of silt which is deposited in islands and along the river banks. the town of niinekolymsk was located on o n e of the islands not far from the river delta. t h e town, which had previously accommodated both russian trappers and c u k t a herdsmen, prospered until the late 1940s. when most of the settlers moved t o cerskij. today niinekolymsk is almost deserted with only a few inhabitants remaining. t h e kolyma water masses carry a great amount of heat from the south. this, and isolation from the north by the a n j u j mountain ridge, makes the local climate in the lowlands milder and the vegetation richer in contrast t o the surrounding tundras. continental climate dominates in the areas. t h e mid-january temperature at the timberline is -34°c. and -32°c at the coast. t h e july temperatures a r e + 12 and + 6°c at timberline a n d t h e coast, respectively (northern jakutija 1969). a t the konkovaja river the tem peratures in mid-july a r e +7”c (potapov 1993). t h e timberline extends along the kolyma river u p t o t h e former village “kraj lesa” (edge of the forest), approximately 100 km from niine kolymsk. larch trees larix daurica grow along t h e river. t h e river banks a r e flanked with the kolyma willow salix kolymensis and alder alnus fructosa. t h e northernmost islands of the delta a r e bordered by grey willow s. glauca and covered by tundra vegetation. tundra vegetation is also predominant o n t h e so-called chalarea tundra, northwest of niinekolymsk. t h e entire terrain in lower kolyma is underlaid by permafrost. the collection species identification has been made according to allen (1914), ognev (1926. 1931. 1935, 1940, 1947, 1948, 1950) and corbet (1978). all measurements taken by koren were in inches and have been transformed into mm. calculations of means and s d were made in inches and then transformed into mm. t h e nomenclature follows corbet (1978, 1984), but additional comments to the taxonomy of the different species are also given. complete lists of all data available for each specimen in the collection are given in appendices 1-3. insectivora soricidae t h e taxonomy of the palearctic shrews has been unclear for some time. recent russian studies (dolgov 1967; judin 1971; ochotina 1983; small mammals from the koren arctic expedition to the kolyma river 3 fig. 1. i 4 cernjavskij 1984; krivoseev 1984; dolgov 1985; pavlinov & rossolimo 1987; dokueaev 1990) on systematics, morphology (reproductive organs and karyotypes). ecology, and distribution have provided new information on the taxonomical status of siberian shrews. f . mehlurn & e . porapov sores roboratits hollister. 1913. flat-sculled shrew this shrew from kolyma was described by allen (1914) as a new species sorex uir. it was regarded by ellerman br morrison-scott (1966) as con specific to s. araneits l.. 1758, but later russian authors (judin 1971; cernjavskij 1984) treated i t as a s . oir. t h e current point of view is that this species is conspecific to s . roboratits hollister, 1913 (krivoseev 1984; hoffman 1985: pavlinov br rossolimo 1987: d o k u t a e v 1990). the collection contains 29 specimens of this species (table 1). this large shrew was thought to b e the most common in the niinekolymsk area (allen 1914). i t is widely distributed in the taiga zone of the kolyma lowlands and can be found in the cotton-grass tussock tundra habitat as well as in meadows along river stretches and lakes (tavroskij et al. 1971). tahlr i . s u m m a r y table o f m e a s u r e m e n t \ ( i n m m ) of su1e.r rohorurur for n i d c \ and temalcs collected in the k o l y m a regicin se\ h l r j \ u r e m s n t n 'i \d rdngc total l c n p t h 18 1 0 h . s h y 97-117 m a l e s l.ail length 18 36.3 2 5 31-41 h i n d toot 18 15.0 0 . 5 14-16 t ~ t a l l e n g t h i) 108.3 5.6 102-117 females t.111 length 9 36.8 1 0 36-39 hind foot 9 15 1 (1.5 14-16 sores tirndrensis merriam. 1900. arctic s h r w allen ( 1914) described the specimens collected by koren on his previous expedition to kolyma as a new subspecies of 5'. uruneils l . . 1758, which he named s. ciraneiis ultiniio. this shrew was treated by c'orhet (1978) as the subspecies s. arcticur horrulis. neither ellerman & morrison scott (1966) nor kuzyakin (1965) regarded s. urcticits kerr. 17y2 as a separate species. as did later russian authors (stroganov 1957; corbet 1978). the current point of view is that this shrew belongs t o the species s. fundrutisis merriam. 1900 (ochotina 1983; cernjavskij 1984; corbet 1984; krivoseev 1984; pavlinov & rossolimo 1987; dokueaev 1990). t h e r e a r e two specimens of this shrew present in the collection. sorex ciapkaenodon sanguinidens (allen, 1914). large-toothed shrew a new species s. sanguinidens was described by allen (1914) from the kolyma region. most specialists (ellerman & morrison-scott 1966; cernjavskij 1984; pavlinov & rossolimo 1987) treated this species as conspecific to s. daphaen odon thomas, 1907. corbet (1978) and krivoseev (1984) treated this shrew as a subspecies s. d . sangitinidens. t h e same point of view was expressed by tavrovskij et al. (1971) who pointed o u t that specimens of s. d . sanguinidens from the lower kolyma a r e smaller than those from central jakutija. this species is represented by ten specimens in the present collection. currently this shrew is abundant in the meadows along rivers and lakes. i t also inhabits larch forests in the river valley (tavrovskij e t al. 1971). lagomorpha o c h o t o n i d a e ochorotza hyperhoreii (pallas. 1811). northern pika allen (1903) described a new species ochotona kolvtnensis from t h e kolyma region. later it was treated as a subspecies of the widely distributed 0. alpina (pallas, 1773) (corbet 1978: tavrovskij et al. 1971; krivoseev 1984), but after closer studies it was regarded as a separate species 0. iiyperborea (cernjavskij 1984: corbet 1984; pav linov & rossolimo 1987). the collection contains eleven specimens of this pika (table 2). according t o koren (allen 1914) it is found in rocky areas in the region. recent observations show that it inhabits both the mountain tundras east of the kolyma and the plain tundras west and northwest of the kolyma. i t does not occupy bush and forested habitats between the high terraces o n each side of the kolyma river valley but prefers the stony habitat of the mountain areas west of the kolyma and small mammals from the koren arctic expedition to rhe kolyma riuer 5 table 2 . summary table of measurements (in mm) of ochotona hyperborea for males and females collected in the kolyma region sex measurement n x sd range totallength 6 157.7 10.6 142-166 males tail length 4 11.4 3.7 8-15 hind foot 6 27.1 0.8 26-28 total length 5 153.5 9.0 145173 females tail length 4 11.7 3.6 6-14 hind foot 5 25.7 1.7 24-28 dry polygons with deep, dry, frost-trenches in the tundras east of the kolyma and north of niinekolymsk. tavrovskij et al. (1971) considers this species to be very common between the sta duchina stretch and the konkovaja river. it was mentioned by buturlin (1913) as a common species in the delta. rodentia sciuridae sciurus uulgaris uulgaris l., 1758. red squirrel ellerman & morrison-scott (1966) classified populations from this region as belonging to the subspecies s. u. jacutensis ognev, 1929, while corbet (1978) included it in the nominative sub species. the latest revisions (cernjavskij 1984; krivoseev 1984) treated the populations from the lower kolyma as s. u . jukutensis ognev, 1929). a total of five specimens are present in the collection. according to koren (allen 1914), it is found in the larch forests along the kolyma river. the red squirrel is common in all types of forests and spreads up to the northern limits of the timberline. krivoseev (pers. comm.) found the squirrel even in tundra habitats. along the east bank of the kolyma it is found up to the north ernmost limits of the forest (e. potapov unpubl.; tavrovskij et al. 1971). marmotu camtschatica (pallas, 1811). black capped (kameatka) marmot this marmot was treated by ellerman & mor rison-scott (1966) as a subspecies m . marmota carntschatica, but was later given species rank (corbet 1978), which has not been disputed by recent studies (cernjavskij 1984; krivoseev 1984; pavlov & rossolimo 1987). this species is represented in the collection only by a lower jaw (no. 177). according to koren (allen 1914), it can be found in wooded highlands. this record is of great importance as even now the distribution of this species in the region remains unclear. until the re-discovery of the koren’s collection there was no evidence of presence of the species in the lower kolyma. buturlin (1913) noted an isolated population of this species at “65 km from sukharnyj”. he prob ably meant either the sukharnaja river (the northeast tributary of the kolyma) or the sukh arnyj island in the delta. later cernjavskij (1984) referred to personal communications from vari ous sources which suggested that isolated colonies of this species could be found at the sources of the pogynden river (which flows from the same area as the krestovaja river, but which was a tributary of the malyj anjuj river). none of the mentioned observations were supported by specimens, and thus it was concluded that there was no evidence of this species in the anjuj range region (gromov & poljakov 1977). the jaw from koren’s collection provided such evidence. there is no indication that koren consulted the sources of the pogynden or sucharnaja rivers, but it is possible that he acquired the jaw from local nomadic herdsmen. since buturlin’s expedition to the lower kolyma nobody has checked the information of marmot colonies in the sucharnaja river, but even now local trappers and fishermen state that the species occurs in the area. the nearest known colonies of the kameatka marmot are at the kor yak mountains (800 km se) or in the jakutija (upper indigirka, 500km or the lower lena river, 500 km). small scattered colonies of the kameatka marmot were recorded at the pyrgenau ridge, south of the cape let’jatkin, 65 km east of the kolyma delta (voveenko et a]. 1987; bibikov 1989). to support the latter finding, one skin has been kept in the zoological museum of the moscow state university (krivoseev, pers. comm.). there is an indication that in 1920s some colonies of the kameatka marmot were present in the lower indigirka (tavrovskij et al. 1971). during the most recent expeditions to the region no marmots were found (solomonov 1987). as there is no evidence, that koren visited coastal areas east of the kolyma, the marmot’s jaw in his 6 collection possibly comes from the northernmost point of the range, either from a population not yet discovered or from an already extinct popu lation. the “wooded highlands” mentioned by koren (allen 1914) is the most unusual type of habitat for marmots. the typical habitat of the kameatka marmot includes gentle, steppe-like vegetation slopes in high mountain areas. or places of similar character near the sea coast. the marmot avoids stony, steep slopes and forested areas (tavrovskij et al. 1971; cernjavskij 1984). the nearest iso lated population in the north anjuj range (vov eenko et al. 1987) lives in stony mountain tundra at least 90 km from the current timberline. f. mehlum & e . potapov pteromys volans l., 1758. flying squirrel this species is represented in the collection with only one specimen. according to koren (allen 1914), it is found in wooded areas in the kolyma. this species is very difficult to detect in summer, and there are no winter observations from this region. it is highly possible that the flying squirrel could still be found in the larch forests of the lower kolyma river. the nearest known location is the mid-omolon river, mid and lower anjuj river (cernjavskij 1984; krivoseev 1984). according to tavrovskij et al. (1971) the northern limit of the range of the flying squirrel in the kolyma is the srednekolymsk settlement at the mouth of the osetrovka river, i.e. ca. 200 km south of niinekolymsk. spermophilus parryi lertcosticus brandt, 1844. arctic souslik cricetidae allen (1903) described a new species citelllls bax toni from eastern siberia. later, ognev (1947) suggested that the north american species s. parryi (richardson, 1825) is close to the east siberian souslik c . undulatus (pallas, 1778). the latter opinion was supported by a detailed study of gromov et al. (1965) who treated the north eastern populations of s. undulatus as conspecific to s. parryi and separated them from the southern populations of s. undulatus. the study of gromov et al. (1965) was based on the morphological analysis and supported by chromosome analysis by ljapunova (1969). this opinion was widely accepted (cernjavskij 1984; krivoseev 1984; pav lonov & rossolimo 1987). the present collection includes two specimens of this souslik. it was not included in the collection studied by allen (1914). according to allen (1914) koren reported that this souslik was com mon in the tundra around the mouth of the kolyma river. today the arctic souslik occurs only along the eastern side of the delta and is not dicrostonyx torquatus (pallas, 1778). collared lemming allen (1914) described a new species d . chion opaes from kolyma. later this lemming was given status as a subspecies d . torquatus chionopaes or included in d . t . lenae kerr, 1792 (corbet 1978). the collection contains only one specimen of this lemming, a skin in winter fur. the only data available consists of “skin prepared by a native, no measurements”. today the collared lemming can be found on the large islands of the kolyma delta and in the tundras approximately 35 km north of the niinekolymsk. this specimen could in n o way have been obtained in the forested habitats along the river valley, an area never used by this species even during peak years. the specimen probably originates from the chalarea tundra (which is the location of the nearest known populations), the avan-delta of the kolyma, or from the mountain tundras of the eastern side of the kolyma. found on the banks of the o r on myopus schisticolor thayeri (allen, 1914). wood the islands of the kolyma delta. it also occurs in all high terraces on the eastern side of the kolyma lemming river and both malyj and bol’soj anjuj and omolon rivers. it is common in most of the places and on the right hank of the lower kolyma its population density was described as the high. (tavrovskij et al. 1971). in order to obtain a specimen koren had only to cross the kolyma river near niinekolymsk and go to the high terrace across the boggy part of the valley. based on two specimens found dead in the snow during koren’s expedition to the kolyma in 191 1 12, allen (1914) described a new species m . t h a y eri. later i t was treated as a subspecies of m . schisricolor (liljeborg, 1844) (ognev 1948; ternjavskij 1984). the present collection contains only one speci men. recent studies mentioned this species as a small mammals from the koren arctic expedition to the kolyrna river 7 fairly common animal in the larch forests in val leys of the omolon and anjuj rivers (cernjavskij 1984; krivoseev 1984), as well as in the forests and bushes along the western side of the kolyma up to the pochodsk settlement (tavrovskij et al. 1971). the habitat of this species includes green mosses which are very common in koren’s study area. lemrnus sibiricus chrysogaster (allen, 1903). siberian lemming allen (1903) described a new subspecies l. obensis chrysogaster based on specimen from the river gyiiga, north of the ochotsk sea. the siber ian lemming population there is small and isolated. later allen (1914) treated the latter as a separate species l. chrysogaster. the siberian lemming from the kolyma delta (locality kala shevo) was described as a new species l . paulus allen, 1914. later these two lemmings were treated as conspecifics. although at present lem mings from the chukotka peninsula and plain tundras east of the enisej river are treated as l. s. chrysogaster, the status of the isolated popu lation from the gyiiga river remains unclear. sidorowicz (1964) made a revision of the genus lernmus and treated all three species ( l . sibiricus, l . trirnucronatus, l . lemmus) as con specifics. this was criticised by various authors (see e.g. gromov & poljakov 1977). krivoseev & rossolimo (1966) treated l. sibiricus as con specific with l . trirnucronatus, whereas this ques tion was left unanswered by raush & raush (1975). the latter authors treated l. chrysogaster as a subspecies of l. sibiricus. this point of view was later supported by cernjavskij (1984). three specimens are present in the collection. according to koren (allen 1914), it was common in the kolyma region even if he only was able to obtain one specimen during his first kolyma expedition. the nearest sites koren might have collected the animal from are the same as described for the collared lemming. another possibility is that the specimens come from a forest-tundra population which is known in near srednekolymsk area (krivoseev & rossolimo 1966; tavrovskij et al. 1971). the animals from the latter population are known to be smaller than the ones from the tundra zone. krivseev (pers. comm.) caught one siberian lemming at the staduchina stretch, approximately 20 km from niinekolymsk. clethrionomys rutilus jochelsoni (allen, 1903). red-backed vole allen (1903) described this vole as a new species euotornys jochelsoni based on two alcohol-pre served specimens from verkhnekolymsk (now zyrjanka). among the character distinctions sep arating the new species, allen (1903) mentioned bright-red spots on the back and bright yellow spots on the sides. eerjavskij (1984) noted that this might be a result of the method used for preserving the skin. gromov and poljakov (1977) treated this vole as c . r . jakutensis; however this point of view was not supported later (cernjavskij 1984; krivoseev 1984). the collection contains 26 specimens of this vole (table 3). according to koren (allen 1914) the red-backed vole is abundant around niine kolymsk. most of koren’s specimens were col lected in houses, under loose sticks and planks. this species is very common in the forests on both sides of the river valley. during peak years it is recorded north to the typical tundra sub-zone (potapov 1993). along the kolyma river it nor mally spreads up to the pochodsk settlement on the left bank and up to the place kabachovskaja on the right bank. koren’s “study area” is located in the region of “absolute dominance” of the species (tavrovskij et al. 1971). its density in the lower kolyma reaches twelve individuals per 100 trap-nights (krivoseev 1981). microtus oeconornus koreni (allen, 1914). root vole the specimens collected during koren’s first expedition to the kolyma were described as a new species microtus koreni (allen 1914). ellerman & morrison-scott (1966) treated this vole as a subspecies of m . oeconomus (pallas, 1776). this table 3. summary table of measurements (in mm) of clethriori omys rutilus jochelsoni for males and females collected in the kolyma region sex measurement n x sd range ~ ~ total length 25 112.3 8.1 102-140 males tail length 25 26.9 3.1 19-32 hind foot 2.5 18.9 0.s l b 1 9 total length 1 135 females tail length 1 3.5 hind foot 1 19 8 f. mehlum & e . potapou table 4 . summary table of measurements (in mm) of microtur oeconomur koreni for males and females collected in the kolyma region based on specimens obtained by s. a. buturlin he treated this stoat as m . e . orientalis (ognev, from the pochodsk village in the lower kolyma, measurement n x sd range 1931). geptner et al. (1967) used the subspecies name m . e. kanei, which was later supported by sex total length 42 133.9 14.2 102-173 krivoseev (1984). tavrovskij et al. (1971) and 42 34.8 5.1 24-49 eernjavskij (1984) regarded the stoats from the region as m . e. arctica, while corbet (1978) hind foot 42 20.8 1.3 1623 totallength 3 146.0 1oo-184 treated it as belonging t o the nominate subspecies six specimens are present in the collection. the le5’ m . e. erminea. females tail length 3 33.5 hind f o o t 3 19.3 17-22 stoat is quite common in the area and occupies both the taiga and the tundra zones (krivoseev 1984, potapov 1993). opinion was supported by tavrovskij e t al. (1971), eernjavskij (1984), and kriviseev (1984). the collection contains 48 specimens of this vole (table 4). it is very common along the kolyma river and on the islands in the river (tavrovskij et al. 1971; krivoseev 1981). its num bers there reaches 16.3 individuals per 100 trap nights (krivoseev 1981). the root vole also lives in the tundra north of the niinekolymsk (potapov 1993) and in the delta. carnivora canidae canis lupius l . , 1798. wolf the collection contains only one specimen of the species (female, no. 151b). the wolf is said to be common in the area (allen 1914). buturlin (1913) mentioned that wolves increased their numbers in the lower kolyma. from the 1960s to 1990 the population of wolves in the tundra region was controlled and their numbers were reduced. today the number of wolves in the region increases (potapov unpubl.) it breeds both in the tundra and i n forested areas. musteiidae mustela erinineu erminea l . , 1758. stoat allen (1914) mentioned two specimens collected by koren and identified them to mustela kaneii baird, 1857, a weasel described from the arak chechen island. h k o t s k i j peninsula. ognev ( 1931) considered the name karieii inappropriate as the description of this species was based on specimens from different parts of the palearctic. mustela niualis pygrnaea (allen, 1903). least weasel allen (1903) treated this weasel from the lower kolyma as conspecific with putorius pygrnaeus, a new species he described from the gyiiga river. later it was treated as conspecific with mustela niualis l., 1766. (ellerman & morrison-scott 1966). recent authors treated weasels from the lower kolyma as m . n. p y g m a e a (geptner et al. 1967; tavrovskij et al. 1971; eernjavskij 1984; krivoseev 1984). the collection contains seven specimens of this weasel. this species is not mentioned in the paper describing the material from the first koren’s expedition to the kolyma (allen 1914). recently this species was observed at a number of locations in the lower kolyma including forested areas and the tundra (potapov 1993). felidae l y n x lynx l., 1758. north-siberian lynx the lynx from yukutia is treated by tavrovskij et al. (1971) as the north-siberian lynx lynx l v n x wrangeli ognev, 1928. the collection contains only one skull of this species (no. 181, collected at niinekolymsk, other script unreadable). the species is said to inhabit the upper kolyma highlands (allen 1914). the occurrence of this species in the lower kolyma and the lower anjuj river was mentioned by iochel’son (1898). cernjavskij (1984) states that this species occurs everywhere in the forested part of the region, but very rare. in the kolyma lowlands this species is very rare (tavrovskij et al. 1971). small mammals from the koren arctic expedition to the kolyma river 9 general discussion studies of the local fauna in the lower kolyma region began in the 19th century when the area was visited by matjugkin and vrangel’ (vrangel’ 1841), and later by maidell (1894) and iochel’son (1898), all of whom made observations and col lected animals. in 1892 the kolyma river was visited by i. cerskij (revzin 1952), who collected birds and mammals. this collection, lodged at the zoological institute, st. petersburg, covers specimens from the taiga of the kolyma river, but includes few tundra specimens due to the untimely death of i. cerskij which brought the expedition to an end. in 1905 the kolyma low lands were visited by buturlin (1913), who also collected birds and animals. later the region was visited by gribanovskij (1915). the material collected during koren’s first expedition to lower kolyma added valuable information t o the knowledge of the fauna of small mammals of the region. (allen 1914). more recently the mammals of the region were studied by krivoseev, who stayed in the pochodsk settle ment from 1960 to 1963 and intensively travelled within the region. the results of his research were summarised later by tavrovskij et al. (1971) and krivoseev (1964, 1981) and they were included in a comprehensive study by cernavskij (1984). potapov (1993, 1994) stayed in the proximity of the pochodsk settlement in 1985 and made occasional visits t o the kolyma delta and the mountains east of the river. in 1982-1983 and in 1986-1992 he studied small mammals in the tundras north of koren’s study area. the present collection is not representative for the whole fauna of the terrestrial mammals in the kolyma river region in the period 1915-1917; it indicates, however, the geographical range of koren’s activity in the region. lack of species such as the arctic fox alopex lagopus (l., 1758), red fox vufpes uulpes (l., 1758), wolverine gulo gulo (l., 1758), sable martes zibellina (l., 1758), arctic hare lepus tirnidus l., 1758, elk alces alces (l., 1758), reindeer rangifer tarandus (l., 1758) and brown bear ursus arctos l., 1758, is undoubt edly a result of koren’s commercial activity. how ever, it is still not clear why koren left squirrels in the collection. the squirrel is a very valuable fur animal in the region (iochel’son 1898; maidell 1894; tavrovskij et al. 1971). the same applies to the weasel. although the total number of speci mens in the collection is 152, the specimens were given numbers up to 181 and thus several speci mens are missing. the missing numbers might have belonged to fur specimens sold by koren in vladivostok. schaanning (1954) claims that the collection had suffered during its transportation from kolyrna, as a large number of the bird eggs were broken and several bird skins were missing. perhaps some mammal skins might have dis appeared during the transportation. the presence of the kameatka marmot and lack of the bighorn snow sheep ovis nivicola eschscholtz, 1829, implies that either the marmot’s jaw could have been obtained from local hunters or koren may have indeed encoun tered a unique colony living in “forested highlands”. the collection also lacks the masked shrew sorex caecutiens laxmann, 1788, which is quite common in the region (tavrovskij et al. 1971; cernjavskij 1984). this could be explained by the fact that koren probably did not have any sophisticated traps, or did not catch the shrews deliberately. the lack of middendorff’s vole microtus mid dendorffi (poliakov, 1881) and especially narrow sculled vole m . gregalis (pallas, 1779) suggests that koren never visited the tundra areas to the north of niinekolymsk and in the western part of the kolyma delta. these parts of the region have very high numbers of the narrow-sculled vole which cannot be missed. the narrow-sculled vole occurs in many parts of the lower kolyma and can be found even in verkhne-kolymsk (tav rovskij et al. 1971). this is indirectly supported by the small numbers of siberian and collared lemmings represented in the collection. these species dominate in the tundras in the kolyma delta and in the plain tundras north of the niine kolymsk. both lemmings are detectable even dur ing low periods of the cycles as their remains could be found everywhere in the tundra in owl’s pellets and old nests. it appears that koren only visited the right bank of the kolyma delta, and possibly the kabachovskaja river at timberline. there he might have collected siberian lemming, marmot, and souslik. this is the only place where koren could have collected whimbrel numenius phaeopus, great knot calidris tenuirostris and naumann’s thrush turdus naumanni included in his bird collection (schaanning 1954). the species of the taiga fauna are well repre sented in the collection, except for grey-sided vole clethrionomys rufocanus (sundevall, 1846) which lives in all forests in the river valley together with 10 f. mehlum & e . potapov the red-backed vole and also in the forested slopes of the mountain. in the omolon river the density of grey-sided vole was found t o b e much lower numbers than red-backed vole (cernjavskij 1984). this probably explains lack of this vole in the collection of koren. however, krivoseev (1981) has found grey-sided vole in the kolyma lowlands in quite high numbers (up to ten indi viduals per 100 trap nights). small mammals inhabiting mountain regions are also lacking in the collection. t h e lack of the siberian mountain vole articola macrotis r a d d e , 1862 and sub-arctic vole microtus hyperboreus vinogradov. 1934, which could b e found in the mountain tundra together with the northern pika (cernjavskij 1984). probably means that the pikas from the collection were obtained from the plain tundras o n the left bank of the kolyma. or in the stony forested slopes of the right bank. there are n o indications from the collections made by koren or the knowledge of the present status of small animals in the lower kolyma region that any small mammal species have suf fered any significant decline in distribution o r abundance since the beginning of this century. acknowledgertient~. we would like to thank j . a. pedersen. the f o n c r curator of mammology at the zoological museum. university o f oslo for giving the pnncipal author access to koren's snail mammal collection and for assistance in the taxonomical work. thanks also to the present curator of mam mology. 0 . wiig and an anonvmous referee lor valuahle help with the final manuscript. e . potapov's research at uppsala, sweden i s supported b! olle & signhid engkvists stiftelser and wwfi sweden references allen. j . a. 1903: rcport on the mammals collected in north eastern siberia b! the jrsup north pacific expedition, with itinerar) and field notes by n. g . buxton. bull. am. mu. nar. h b r o q 19. l(11-184 allen. g . m 1914: notes on the birds and mammals of the arctic coast o f sihcria proc nkh. england zool. ciuh 5 pp. 40-66 amundsen. r . 1921 : .vordosrpassagen. maudferdeen langs asi ens kyst. gyldendal. kristiania. bibiko\. 11 i . 198y. s u r k i (marmots). agropromlzdat. buturlin. 5 . a 1913. nabljudenija nad mlekopitajusfimi. sde lannyr v o \ remja kolymlkoj ekspedicii 1905 g. [ohsewations of mammal5 made during the kolyma expedition 1w)sl. l h r i v i ' i h zoo1 ord oh-ua ljuhi ejresriioznan , aniropol. i kfnogrufri. .l'oo. .wr. t. 11.7). [notes zool. dept. nat. hist. anthro. ethnogr. soc.. i i . $ . l ( 5 ) ] . pp. 2 2 s 2 6 6 . ccrnjavskil. f. b. 1984: mlekopiraluftie krajnego sewro-vos roko .'chin (mammals of the extreme north-eastern siberia). m o r c o \ + . 255 pp s;iuka moscow 38y pp. corbel. g . b. 1978. mammals of rhe palearctic region: a raxonomic reuiew. cornell univ. press. british museum of natural history. corbet, g . b. 1984. mammals of the palearctic region: a taxo nomic reuiew. supplemenr. cornell univ. press. british museum of natural history. dokufaev, n. e. 1990. ekologija burozubok seuero-vosrofnoj a z i i . 160 c. [ecology of shrews of northeast asia]. nauka. moscow. 160 pp. dolgov, v . a , , 1967 rarpredelenre i eulennosr' palearrifeskiclr burozubok [distribution and numbers of shrews in the pale arctic]. 2001. i u r n . 46(11). 1701-1712. dolgov. v. a. 1985: burozubki starogo suetu. [shrews of the old world]. iz-vo mgu. 221 pp. ellerman. j . r . & morrison-scott. t . c. s. 1966: checklist of palearcric and indian mammals 1758-1946, 2nd edirion. london. evjenth. h . 1938: gunen som norge glemre. gyldendal. oslo. geptner. v . g . . naumov, n. p., jurgenson, p. 9. sludskij. a . a . . cirkova, a . f., bannikov. a . g . 1967: mlekopiru]usfie sooerskogo sojuza. t . 2. v. 2 . [mammals of the soviet union. vol. 2 . part 21. 1004 pp. grihanovskij. n. n. 1915: zametki c) poljarnoj pkspedicii na ko!,.mil [notes on the polar expedition to the kolyma region]. trudy jakutskogo otdelenija rossijskogo imper atorskogo geografieeskogo obxestua. t. 1. [proceedings of the jakut branch of the russian imperial geographical societv. vol i ] . gromov. i. m . . bibikov, d . i . . kalbuchov. n. 1. & mejer, m. n. 1965: nazemnye belit'i. [ground squirrels (marmotinae)]. fauny sssr. mlekoprujujfie. 3 ( 2 ) . [in: fauna of the ussr. mammals. vol. 3 ( 2 ) . ] nauka. moscow-leningrad. 466 pp.] gromov. i. m. & poljahov. 1 . j a . 1977: polevki (microtinae) fauny sssr. mlekopitajugfie. [voles (microtinae) of the fauna of the ussr]. fauny sssr. mlekoprajuffie. t . 3(10). [fauna of the ussr. mammals, vol. 3 (lo).]. nauka. moscow-leningrad. 275 pp. hoffmann 1985: the correct name for the palearctic brown, or flat-sculled shrew is sorex roboratus. proc. bio/. soc. wash. 96 (i). lochel'son, v . i . 1898: o t e r k zveropromyslennosti i torgovli mechami v kolymskom okruge [notes on trapping and fur trade in the kolyma district]. trudy jakurskoj ekspedicii. old. 3 , t . 10 ( 3 ) [proc. of the jakutian expedition. st. peters burg. vol. 3(3)]. pp. 1-1671. judin. b. s. 1971: nasekomoiadnye mlekopirajlci"tie sibiri. [insectivorous mammals of siberia (key)]. nauka. novo sibirsk. 170 pp. krivoseev. v. g. & rossolimo, 0. l. 1966: vnutrividovaja izmenfivost' i sistematika sibirskogo lemminga lemmus sihi ricus kerr. 1792) [intranpecific variation and systematics of the siberian lemming (lemmus srbiricus kerr, 1792) in the palearctic]. moip, bjull. ord. biol. 71. 5-17. krivoseev. v . g. 1981: faktory reguljacii fislennosti myse vidnych gryzunov i chjifnych mlekopitajusfich tajgi kolym skoj nizmennosti. ekologija rrilekopirajuecich .veoerooo srofno] sibrri. c . 61-82 [factors of small and predatory mammal numbers regulation in the taiga of the kolyma lowlands. in: ecology of mammals of ne siberia] nauka, moscow. pp 61-82,] krivoiecv. v. g . (cd.) 1984: nazemnye mlekoyirajusffie dal'nego vosroka sssr. opredelirel'. [terrestrial mammals of the far east of the ussr. identification keya. nauka. moscow]. 356 pp. kuzvakin. a . p . 1965: inscctivora and chiroptera. i n bobrin small mammals from the koren arctic expedition to the kolyma river 11 skii, n. a . , kuznetsov, b. a. & kuzyakin, a. p . (eds): opredelitel' mlekopitajus-fich sssr [classification of the mammals of the ussr]. moscow. ljapunova, e . a. 1969: opisanie chromosomnogo nabora i podtvertdenie vidovoj samostojatel'nosti citellus parryi (marmotinae, sciuridae, rodentia). [description of the chro mosome set and confirmation of the species status of cifellus parryi (marmotinae, sciuridae, rodentia)]. mlekopitajuseie (evoljucija, kariologija. sistematika, faunistika). [in: mam mals (evolution, karyology, systematics, fauna)]. nouos ibirsk, 53-54. maidell, g . 1894: journey to the northeast yakutia region in 18611870. appendix to vol. 74. proc. russ. imp. acad. scr. ( s t . petersburg) 74 (3) suppl. (in russian). ochotina, m. v. 1983: taksonomifeskaja revizija sorex arcticus, kerr, 1792 (soricidae, insectivora) [taxonomical revision of sorex arcticus, kerr, 1792 (soricidae, insectovora)] 2001. iurn. 62(3), 40%417. ognev, s. i. 1926: zueri vostoenoj europy i seuernoj azii. cast' i . nasekomojadnye i letutie myfi. t . 1 . [mammals of eastern europe and northern asia. vol. 1: insectivora and chiroptera. vol. 11 iz-vo an sssr. moscow-leningrad. 631 pp . ognev. s . i. 1931: miekopitajdeie vostocnoj europy i severnoj azii. cast' 2 . chislxnye mlekopitajuieie. t . 2 . [mammals of eastern europe and northern asia. vol. 2: carnivora.]. iz-vo an issr. moscow-leningrad. ognev. s . i . 1935: zuerisssriprileiaifichshan. t . 3: chiftnye i lastonogie. [mammals the ussr and adjacent countries. vol. 3: carnivora and odobendae]. iz-vo an ussr. moscow-leningrad. 752 pp. ognev, s. i . 1940: zueri sssr i pri1eias"eich stran. t . 4: gryzuny. [mammals of the ussr and adjacent countries. vol. 4: rodents]. iz-vo an sssr. moscow-leningrad. 615 pp ognev, s . 1. 1947: zueri sssr i prile2as"tcich strati. t . 5: gryzuny. [mammals of the ussr and adjacent countries. vol. 5: rodents]. iz-vo an sssr. moscow-leningrad. 809 pp. ognev, s . i. 1948: z u e r i s s s r i p r i l e i a s ~ e i c h s t r a n . t . 6: gryuny. [mammals of the ussr and adjacent countries. vol. 6: rodents]. iz-vo a n issr. moscow-leningrad. 559 pp. ognev, s . i . 1950: zveri s s s r iprileiaffich stran. t . 7. gryzuny [mammals of the ussr and adjacent countries. vol. 7: rodents]. iz-vo an issr. moscow-leningrad. 706 pp. pavlinov, i . ja. & rossolimo. 0. l. 1987: sistematika mle kopitajuitich s s s r . [systematics of the mammals of the ussr). nauka, moscow. 282 pp. potapov, e . r . 1993: ecology and energetics of rough-legged buzzard in the lower kol-yma riuer. doctorate thesis, uni versity of oxford. potapov, e. r . 1994: checklist of birds of the lower kolyma (ne siberia). bull. brit. omirhol. club 114(2), 6 6 7 3 . raush, r. l. & raush, v. r . 1975: taxonomy and zoogeog raphy of lemmus spp. (rodentia, arvicolinae) with notes on laboratory-reared lemmings. ztschr. saiigetierk 40 (1). b 3 4 . revzin, g. i. 1952: zirn'tpoduig iuana cerskogo [the life and heroism of ivan cerskij]. moscow. riley, j . h. 1918: annotated catalogue of a collection of birds made by mr. copley amory. j r . , in northeastern siberia. proc. us nat. m u . 54, 607-626. schaanning, h. t. l. 1920: johan koren 1879-1919. norsk jeger-og fiskerforenings tidsskr. schaanning, h. t . l. 1954: a contribution to the ornithology of eastern siberia. n y t t magasin for zoologi 2 , 91-115. sidorowicz, j. 1964: comparison of the morphology of rep resentatives of the lemmus from alaska and palearctic. acta teriol. 8(14), 217-226. solomonov. n. g. (ed.) 1987: krasnaja knrga jakutskq assr [red data book of the jakut assr]. nauka. siberian department. novosibirsk. 99 pp. stroganov, s. u. 1957: zueri sibiri (nasekornojadnye) [mam mals of siberia (insectivora)]. iz-vo a n sssr. moscow. 267 pp. tavrovskij, v . a. (ed.-in-chief). egorov, 0. v., krivogeev. v. g . , popov, m. v. & labutin, ju. v. 1971. mlekopitajusi-ie jakutii [mammals of jakutija]. nauka, moscow. 670 pp. thayer, j . e. & bangs, 0. 1914: notes on the birds and mammals of the arctic coast of siberia. proc. new england zool. club, cambridge, massachusetts. vol. 5 , 1-48. vrangel', f. p. 1841: putesestuie po seuernym beregam sibiri i p o ledovitomu morju. c 1 . 385 pp, f . 2. 365 pp. [journey along the northern coasts of siberia and the northern sea made in 1820-1824. part 1. 385 pp. part 2. 365 pp.]. st. petersburg. voveenko, v. e . , gonearov, 0. n. & krivoseev, v. g . 1987: geografieeskij izoljat eerpnosapoenogo surka (marmota camtrchatica) v anjujskom chrebte [a geographically iso lated population of the kamfatka marmot (marmota camts chatica) in the anjuj mountains]. zool. iurn. 66, 954-956. appendix 1 . sex, locality, date, and measurements (in mm) of shrews (soricidae) collected in the kolyma region. (f = female, m = male, r . k . = river kolyma) no. sex locality date total length tail length hind foot sorex roboratus 20 f r.k. 05.11.1915 109 36 14 r.k. 14.11.1915 111 41 14 102 37 15 21 m 28 f r.k. r.k. 19.11.1915 112 38 15 112 37 15 37 m r.k. 112 39 15 38 m 39 m r.k. r.k. 20.11.1915 116 3 1 15 114 39 16 41 m r.k. 108 36 15 42 m r.k. 109 37 16 44 f 45 m r.k. 12 f. mehlum & e. p o t a p o i ~ a p p e n d i x 1. continued no. s e x locality date total length tail length hind foot m r . k . 23.11.1915 i i6 40 16 47 m r . k . 117 39 15 46 48 m r.k. 1 i4 36 16 r . k . 24.11.1915 i 0 4 31 15 104 36 15 54 m r . k . 114 37 16 55 f 56 f r . k . r . k . 27.11.191s 103 36 15 1 i4 37 15 60 f 65 f r . k . 66 f r . k . 28. i i . 19 15 i17 36 15 105 m r.k. 09.01.1916 104 36 16 i15 m r . k . 27.01.1916 98 32 15 116 m r.k. 97 34 14 1 i7 m r . k. 99 36 15 118 m r . k . 104 38 15 119 m r . k . 01.02.1916 99 37 15 120 m r.k. 100 35 15 135 m r . k . 10.03.1916 99 34 15 136 f r.k. 105 39 16 i44 m r k. 20.03.1916 109 37 15 sorex iundrensis 61 f r . k . 27.11. i915 95 32 13 93 f r.k. 01.01.1y16 84 33 13 20 m r . k . 16.11.1915 78 28 13 43 m r.k. 20.11.1915 81 31 14 52 m r.k. 24.11.1915 81 29 13 62 m r . k . 27.11. i915 78 31 13 63 f r . k . 27.11.1915 85 33 13 sorex d a p h a e n o d o n s u n p i n i d e n s a p p e n d i r 2. sex. locality. date. and measurements (in mm) of lagomorphs (lagomorpha) and rodents (rodentia) collected in the kolyma region. (f = female. m = male. r . k . = river kolyma. n.k. = niinekolymsk) no. sex locality date total length tail length hind foot ochotona h?perborea 32 f r . k . 36 m r . k . 82 f r . k . 83 f r . k . 92 f r . k . 97 f r . k . 122 f k.k 125 m r . k . i28 f r k. 147 f r.k. 171 f n . k . sciurus r,ulguris uulguris 14 m n k 15 f n.k. i y m r.k 26 f r . k . i62 m r.k sprrmophilris p a r r p leuco~ticils 175 m mouth of r.k. 176 f mouth of r . k . piernmy7 rioluris 152 m r . k . 15.11.1915 18.11.1915 08.12.191 5 08.12.191 5 02.01.1916 06.01.1916 1 5 .02 .19 1 6 26.02.1916 03.03.1916 22.03.19 16 05.04.19 i7 21.09.1915 21 10.1915 10.11.1915 25.06.1916 09 07.1917 12.03.1916 166 157 144 157 142 153 158 143 173 158 159 404 40 1 384 413 373 325 305 '64 6 9 14 14 13 15 8 14 169 174 154 154 174 103 90 100 28 27 24 24 25 26 27 28 28 26 26 66 66 64 66 66 69 69 37 s n i ~ i l rnurnnznls f r o m the koren arctic expedition to the kolymn river 13 a p p e n d r r 2 continued no sex localit! date total length m y o p ~ o .scl~i.strcolor rhuwrr 102 m r . k . l e m m a ribrrrcics chrvsogusrrr 124 m r . k . 172 m n . k . cledirronoii~rs rurrlirs ~oclrrhoni i23 m r . k . 21 m 22 m 23 m 24 m 29 m 30 bl 96 m 99 m 1 00 m 101 m 102 hl l(13 m 1 09 m 121 hi 127 m 129 hl 13u m 131 m i32 %i 153 m 154 m 155 m 156 m 157 m 1 m) m 161 f r k r k r k r k r k r k r h r k r k r k r k r k r k r k r k r k r k r k r k r k r k r h r k r k r k r k microrra oeconomw korenr 2.5 m r k . 34 m r . k . 35 m r . k . 40 m r . k . 49 m r . k . 51 .m r . k . 57 m r . k . 5x m r . k . 59 m r.k. 67 m r . k . 68 m r k 69 m r . k . 70 m r . k . 71 m r . k . 72 m r . k . 73 m r . k . 74 m r k. 7 5 m r k . 77 m k.k. 78 m r . k . 79 m r . k . xo m r.k x i m r . k 87 m k.k. xx m r . k . 12 07.1916 17.02. 19 i6 10.06.191: 05.11.191 5 07. i i . 19 15 07 11.1915 14 11.1915 07.01.1916 16.01.1y16 08.0?.1916 28.02.1y i6 05.03.1916 09 0 4 1916 14 in.19l6 23.05.19 i6 27.05.1936 07 11 1915 17.11.19ll 19.11.lyl5 2 3 11.1915 24.11.1915 21 28 0 i 06 1,1915 1.1915 1.1915 2 1915 07 12 1915 22 12.1915 119 1 1 1 104 116 129 109 105 1uy 112 105 102 106 118 i05 106 121 1w 113 112 ioy 110 108 116 1 i6 112 113 i40 135 ins 140 123 141 119 119 136 i46 130 137 127 132 137 129 126 138 130 135 135 138 116 126 134 135 133 118 tail length hind foot 20 18 i8 28 32 27 19 13 26 25 28 24 21 28 26 25 32 26 27 27 27 27 30 29 31 27 27 3 1 35 37 31 34 33 30 32 28 33 32 32 46 38 38 29 39 34 36 39 36 31 32 33 34 37 29 18 18 19 ~ 19 19 19 19 18 19 18 18 18 18 19 18 18 18 18 18 18 18 18 18 19 18 18 18 19 19 22 21 22 11 21 20 21 16 21 22 21 20 20 20 22 20 20 22 21 21 21 22 22 21 20 14 f. mehlum & e . potapov appendix 2 . continued no. sex locality date total length tail length hind foot 89 96 110 111 112 113 114 133 134 139 140 143 145 146 148 149 15 1 164 165 166 168 173 174 m m m m m m m m m m m m m m m m m m m f f m f r.k. r . k . r.k. r.k. r . k . r.k. r . k . r.k. r . k . r.k. r.k. r.k. r.k. r . k . r.k. r.k. r . k . delta of r . k . delta of r . k . delta of r . k . n.k. delta of r.k. delta of r . k . 02.01.1916 17.01.1916 09.03.1916 15.03.1916 18.03.1916 20.03.1916 26.03.1916 04.04.1916 11.07.1916 21.07.1916 28.07.1916 02.07.1917 05.07.1917 117 127 139 131 119 111 134 166 151 173 102 147 158 132 136 143 156 121 100 184 147 153 31 33 36 35 33 31 38 45 41 49 29 39 41 37 37 36 31 25 19 51 24 31 20 21 22 21 20 21 22 23 23 22 19 22 21 22 21 22 19 19 17 22 19 19 appendix 3. sex, locality, date, and measurements (in mm) of mustelids (mustelidae) collected in the kolyma region. (f = female, m = male, r . k . = river kolyma, n.k. = niinekolymsk) ~ ~ no. sex locality date total length tail length hind foot mustela erminea erminea 113 m n.k. 29.08.1915 276 67 36 90 m r . k . 25.09.1915 342 99 46 91 m r . k . 01.10.1915 340 92 46 16 f n.k. 27.09.1915 285 72 37 138 m r.k. 02.10.1915 310 80 43 76 f r . k . 07.12.1915 175 12 21 84 m r.k. 09.12.1915 170 18 23 85 m r . k . 14.12.1915 183 33 25 14.03.1916 141 20 137 f r . k . 141 m r . k . 16.03.1916 198 19 25 150 m r . k . 31.03.1916 179 18 25 170 m n . k . 09.10.1916 163 15 25 147b no data skull only mustela nivalis pygmaea revisiting the extended svalbard airport monthly temperature series, and the compiled corresponding daily series 1898–2018 research article revisiting the extended svalbard airport monthly temperature series, and the compiled corresponding daily series 1898–2018 øyvind nordli1 , przemysław wyszyński2,3 , herdis m. gjelten4, ketil isaksen1 , ewa łupikasza5 , tadeusz niedźwiedź5 & rajmund przybylak2,3 1department of research and development, norwegian meteorological institute, oslo, norway; 2faculty of earth sciences and spatial management, nicolaus copernicus university, toruń, poland; 3centre for climate change research, nicolaus copernicus university, toruń, poland; 4observation and climate department, norwegian meteorological institute, oslo, norway; 5institute of earth sciences, university of silesia in katowice, sosnowiec, poland abstract the svalbard airport composite series spanning the period from 1898 to the present represents one of very few long-term instrumental temperature series from the high arctic. a homogenized monthly temperature series is available since 2014. here we increase the resolution from a monthly to daily basis, and further digitization of historical data has reduced the uncertainty of the series. the most pronounced changes in the 120-year record occur during the last three decades. for the 1991–2018 period the number of days warmer than 0 and 5 °c has increased by 25 (21%) and 22 (59%), respectively, per year compared to the 1961–1990 standard normal. likewise, comparing the same periods, the number of days colder than −10 and −20 °c has decreased by 42 (32%) and 27 (62%), respectively. during the entire time span of the series, the western spitsbergen climate has gone through stepwise changes, alternating between cold and warm regimes: 1899–1929 was cold, 1930–1961 warm, 1962–1998 cold and 1999–2018 warm. the latest cold regime was 1.0 °c warmer than the first cold one, and the latest warm regime was 1.7 °c warmer than the previous warm one. for the whole series the linear trend for annual means amounts to 0.32°c/decade, which is about 3.5 times the increase of the global mean temperature for the same period. since 1991, the rate of warming at svalbard airport is 1.7 °c/decade, which is more than twice the arctic average (0.8 °c/decade, north of 66 °n) and about seven times the global average for the same period. keywords arctic warming; arctic climate; svalbard climate; artic temperature trends; climate threshold statistics; svalbard climate regimes abbreviations afi: air freezing index (see table 4) ati: air thawing index (see table 4) awake: arctic climate and environment of the nordic seas and the svalbard–greenland area project djf: december–february (winter) fd: freeze days (see table 4) gd: growing days (see table 4) gdd: growing degree-days (see table 4) gistemp: goddard’s global surface temperature analysis data set, us national aeronautical and space administration jja: june–august (summer) ip4: inverse proportionality with four corrections mam: march–may (spring) md: melt days (see table 4) met norway: norwegian meteorological institute pdd: positive degree-days (see table 4) rmse: root mean square error son: september–november (autumn) ssr/sst: the ratio of the regression sum of squares to the total sum of squares without using the regression td: thawing days (see table 4) citation: polar research 2020, 39, 3614, http://dx.doi.org/10.33265/polar.v39.3614 copyright: polar research 2020. © 2020 b. ø. nordli et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 27 june 2020 competing interests and funding: the authors report no conflict of interest the research work of eł, tn, øn, rp and pw was supported by a grant entitled causes of the early 20th century arctic warming, funded by the national science centre, poland (grant no. 2015/19/b/st10/02933). the project stations akseløya, svarttangen, crozierpynten and sørkappøya were funded by the polish–norwegian research fund and norway grants, awake project pnrf-22-a i-1/07 (arctic climate and environment of the nordic seas and the svalbard–greenland area). correspondence to: øyvind nordli, norwegian meteorological institute, p.o. box 43, 0313 oslo, norway. e-mail: peron@met.no to access the supplementary material, please visit the article landing page introduction at svalbard airport, a continuous temperature series exists for the period starting 1 august 1975. the airport is close to longyearbyen, along the fjord isfjorden, where several older series are also available (fig. 1a). by combining these series—including observations made by hunting and scientific expeditions—a homogenized, composite monthly mean temperature time series for svalbard airport has been extended back to july 1898 (nordli et al. 2014). the present revisit is motivated by the fact that the series is frequently used by scientists from different disciplines (e.g., gjelten et al. 2016; isaksen et al. 2016; descamps et al. 2017; hamilton et al. 2018; hegerl et al. 2018; osmont et al. 2018; pramanik et al. 2018; woelders et al. 2018; ewertowski et al. 2019). the article by nordli et al. (2014) has been cited more than 100 times and was the most cited paper in the journal polar research in the five years following its publication. further motivation for revisiting the data is that more historical temperature series have been digitized since 2012, enabling both better data control and increased resolution from a monthly to daily basis. fig. 1 (a) map of the northern part of svalbard showing the sites of historical and present-day meteorological stations referred to in this article. (b) map of the svalbard airport and longyearbyen area. (c) part of the runway of svalbard airport. the numbers represent measuring sites during the parallel measurement campaign conducted from 22 september 2015–20 july 2016. site 1 was the official station before the relocation and site 2 the official station after the relocation (see the supplementary material). (maps from toposvalbard, norwegian polar institute.) increasing concentrations of greenhouse gases in the atmosphere are the dominant contributor to the recent arctic warming (fyfe et al. 2013). the heat trapped by greenhouse gases triggers a cascade of feedbacks that collectively amplify arctic warming (amap 2017). these feedbacks include reduction of the sea-ice cover and thereby cause increased release of heat to the atmosphere (overland & wang 2010; overland et al. 2011; alekseev et al. 2016), increased content of water vapour (park et al. 2015), cloud conditions (graversen et al. 2014; pithan & mauritsen 2014), in addition to other drivers such as increased sea-surface temperature (serreze et al. 2011) and inflow of warm atlantic water (overland & serreze 2012). daily data are important for the assessment of, for example, trends in daily-based climate indices, and the study of local factors and feedback mechanisms related to arctic amplification, which are still not fully understood (stuecker et al. 2018). in svalbard, as in the whole arctic, the most recent years are the warmest in the instrumental records (gjelten et al. 2016). the average annual air temperature for svalbard for the 30 years between 1988 and 2017 was 1.5 °c higher than it was during the reference period 1971–2000 (hanssen-bauer et al. 2019). since the beginning of the 21st century, the deviations of seasonal air temperatures from the long-term average of 1898–2017 were all positive for successive years (łupikasza & niedźwiedź 2019). compared to the early 20th century warming, the current warming is stronger (e.g., gjelten et al. 2016; łupikasza & niedźwiedź 2019) and persists over the whole arctic region. moreover, the diminishing sea-ice cover in the fjords contributes to increased temperature locally, especially during the winter months after 2006 (muckenhuber et al. 2016). the increase in temperature after 2000 is primarily driven by the retreat of sea ice, along with higher sea temperatures and a general background warming (isaksen et al. 2016). the extended homogenized svalbard airport temperature series of daily values is our contribution to research that needs to be seen from a historical perspective. for example, the series makes it possible to study long-term variations of threshold statistics that are important for monitoring wildlife, and for understanding how warm winter spells affect the land surface and how building foundations may be affected by thawing permafrost. the new data series, both monthly and daily values, are accessible as a supplementary data set with this article. the series will also be stored in the climate data base of met norway, where all data are freely available on its website https://www.met.no/ with reference to this article. methods, data and metadata regression analysis the svalbard airport composite series is based on direct observations made at svalbard airport over a time period ranging from 1975 to the present, which we will call the principal series. before 1975, it was a composite series consisting of many local series. the composite is established by two steps: (1) quality checking and homogenizing the local series; (2) adjusting the local series to ensure their comparability with the principal series (the svalbard airport site). the local series were checked by using the standard normal homogeneity test introduced by alexandersson (1986). this is a relative homogeneity test that requires reference stations for comparison. however, the number of reference stations is sparse in svalbard, so taking metadata into account is even more important in this context than when working with denser networks. during some periods, the neighbouring stations are so remote that the analysis of the metadata is the only real homogeneity test. inhomogeneities in a data series might be due to radiation screen changes, changed observational procedures, site relocations, etc. after finishing the first step, a network was available in which the principal series as well as the local series were considered to be homogeneous. in the second step, the local series were adjusted to be directly comparable with the principal series based on regression analysis. the daily mean temperature of the principal series, t s, can be written as: where ta, is the daily mean temperature of a local series a that partly overlaps the principal series, α1 and c1 are constants calculated by using the least square method, and ea represents noise (residuals). the predicted daily mean temperature of the principle series, ts, is given by eqn. (2): in some time intervals, more than one local series were candidates for use in the composite svalbard airport series. in such cases, we chose the one that correlated best with the principal series. the residual, e, representing the noise in eqn. 1, is the rmse. another measure of the usefulness of the regression is the ratio ssr/sst, in which ssr is the regression sum of squares and sst is the total sum of squares without using the regression. this ratio shows how much of the variance is accounted for by the regression (wilks 1995). smoothing of the series in order to study variations on selected time scales the time series were smoothed by means of a gaussian filter: gj is the value of the smoothed series in year j, xi is the data point in year i, wj is the weight in year j, n is the number of years in the series and s is the standard deviation in the gaussian distribution. the degree of smoothing is established by the value of the standard deviation in the distribution; for example, a standard deviation of three years corresponds to an approximately 10-year rectangular low-pass filter. regime shifts climate data series may also contain regime shifts (step changes) or a blending of steps and trends (corti et al. 1999). however, interpretations of data in terms of steps and trends depend to an extent on what results are expected, and the scientific background of any particular researcher (bacc author team 2008:14). for the detection of regime shifts a sequential data processing technique, introduced by rodionov (2004), was used. the testing procedure works as follows: for each new observation a test is performed to determine the validity of the null hypothesis, h0 (the existence of a regime shift). there are three possible outcomes of the test: accept h0, reject h0 or keep on testing. in order to decide whether two subsequent regimes were significantly different, student’s test with significance level p = 0.05 was used. testing was continued with the entire data set over the period 1899–2018, now by using a newer version of the rodionov test. this version is designed to handle detection of regime shifts in data sets with autocorrelations by using a so-called prewhitening by the ip4 procedure (rodionov 2006). we also slightly reduced the influence of outliers by using the huber tuning constant (huber 1981), which was set to 2. before testing it is necessary to set a cut-off length, which roughly determines the minimum length of what is accepted as a regime. as was done by nordli et al. (2014), the cut-off length was set to 10 years. metadata and data a comprehensive description of the station data and metadata was given by nordli et al. (2014), so this need not be repeated here. however, since 2014, more data have become available, and metadata have been updated for some stations, as shown in the following text. longyearbyen. for years, the data protocols for the longyearbyen station seemed to have been lost. there existed only old, manually calculated monthly means. parts of the svalbard monthly composite series were based on these old data. a further search for the protocols in 2017 and 2018 was successful, so now additional daily data have been digitized for the period 1916–1939. the longyearbyen series has higher priority than any other local series for inclusion in the composite series, but unfortunately there are many gaps in the longyearbyen series (table 1, fig. 2). table 1 the nine local series used in the composite svalbard series. codea seriesb overlappingc statusd inclusione 0 99840 svalbard airport 1975.07.01–present 1 99860 longyearbyen 1975.08–1977.07 no 1911.08.16–1912.06.30 1916.11.01–1919.09.30 1919.11.01–1920.05.31 1921.09.20–1923.09.01 1930.09.01–1934.08.31 1935.02.01–1935.09.30 1936.11.01–1939.06.30 1945.09.01–1946.08.31 1957.01.01–1975.06.30 2 99820 barentsburg 1975.08–2012.12 no 1934.09.01–1935.01.31 1935.10.01–1935.12.31 1940.01.01–1941.07.31 1947.12.01–1956.12.31 3 99790 isfjord radio 1975.08–1976.07 yes 1936.01.01–1936.10.31 1939.07.01–1939.12.31 1946.09.01–1947.11.30 1996.09–2004.12 2014.09–2018.12 4 99765 akseløya 2010.09–2018.12 yes 1898.09.01–1899.08.08 1900.09.01–1901.07.02 1902.09.01–1903.07.10 1904.09.01–1905.06.30 1910.09.01–1911.06.17 5 99737 svarttangen 2010.09–2012.06 no 1905.07.01–1905.08.19 1906.10.21–1907.07.31 1909.05.01–1909.07.19 6 99732 halvmåneøya 1906.09.15–1906.10.20 1907.08.01–1907.08.31 7 99928 crozierpynten 2010.07–2012.06 no 1899.08.09–1900.08.15 8 99821 green harbour no 1912.07.01–1916.10.31 1919.10.01–1919.10.31 1920.06.01–1921.09.19 1923.09.02–1930.08.31 9 99752 sørkappøya 2010.10–2018.12 yes 1908.09.01–1909.04.30 10 gaps in the series no 1901.07.03–1902.08.31 1903.07.11–1904.08.31 1905.08.20–1906.09.14 1907.09.01–1908.08.31 1909.07.20–1910.08.31 1911.06.02–1911.08.07 1941.08.01–1945.08.31 a1–9 identify the local series; code 0 is the principle series. bthe national station identifiers and names. ccommon data periods between the local series and the principle series. dwhether the additional data prolongs the overlapping period since the publication by nordli et al. (2014). edata period included in the composite series. fig. 2 the nine local series used in the composite svalbard series. svalbard airport is the principle series, indicated in black. the national station identifiers and names of the local series are given in the legend. isfjord radio. a data logger was in operation at the historical site in the period september 1996–december 2004, and in august 2014 met norway opened an official meteorological station at the site. both data periods are used for developing the regression equation homogenizing isfjord radio data for the composite series. periods in the interval january 1934–november 1947 are used (table 1, fig. 2). akseløya and sørkappøya. these started as awake research project stations but were later incorporated into met norway’s ordinary station network. this increases the overlapping period with the principle series from about three to eight years. akseløya is the station that contributes to the earliest interval of the composite series (table 1, fig. 2). svalbard airport. the temperature screen at svalbard airport was relocated on 18 september 2016. parallel measurements were carried out for the detection of a possible inhomogeneity by the relocation, but no corrections were found to be necessary. the measurements are discussed in detail in the supplementary material. results altogether, we used nine different local series in the composite series (fig. 2). there are many gaps in the series, so the inclusion often shifts from one local series to another; see the “inclusion” column in table 1. some of the local series had periods of only two years that overlapped with the principal series when the original article was written (nordli et al. 2014). since then, the included series from akseløya, sørkappøya and isfjord radio have continued to be used even in the present, so the overlapping periods have now increased (table 1). new and statistically more significant regression equations replaced the old ones for these local stations (table 2). table 2 regressions between svalbard airport principle series and local series of daily mean temperature. coefficient jan feb mar apr may jun jul aug sep oct nov dec svalbard airport—longyearbyen (1975–77) αa 1.018 1.038 1.036 1.023 1.049 0.976 1.022 0.929 0.970 0.968 0.971 1.023 ca −0.52 −0.68 −0.88 −1.13 −1.10 −0.87 −1.01 −0.26 −0.57 −0.21 −0.36 −0.04 ssr/sst b (%) 99 99 99 98 98 96 90 92 97 99 99 98 rmse c −0.7 −0.9 −1.1 −0.8 −0.6 −0.6 −0.7 −0.5 −0.4 −0.5 −0.6 −1.2 svalbard airport—barentsburg (1975–2010) αa 1.087 1.089 1.068 1.059 1.048 1.018 0.988 1.031 1.083 1.100 1.096 1.082 ca 0.10 0.22 0.15 0.15 0.47 0.53 0.49 0.16 −0.06 0.11 0.21 0.04 ssr/sst b (%) 94 94 93 94 95 90 84 87 93 94 95 95 rmse c 2.1 2.1 2.2 1.6 0.9 0.8 0.9 0.8 0.9 1.2 1.5 1.7 longyearbyen—green harbour (1911–1930) αa 0.917 0.881 0.822 0.902 0.996 1.002 1.002 1.002 1.051 0.927 0.945 0.829 ca −0.48 −1.04 −1.75 −0.45 0.18 0.79 0.79 0.79 0.03 −0.60 −0.08 −1.21 ssr/sst b (%) 96 90 92 92 94 78 78 78 89 84 92 91 rmse c 2.4 2.9 2.6 2.2 1.2 1.6 1.3 1.1 1.1 1.8 2.1 2.7 longyearbyen—isfjord radio (1957–1977) αa 1.173 1.182 1.159 1.143 1.119 1.206 0.982 1.118 1.174 1.224 1.205 1.184 ca −0.53 −0.55 −0.25 −0.00 0.62 0.96 1.80 0.55 −0.10 −0.57 −0.49 −0.47 ssr/sst b (%) 96 93 94 94 94 66 76 83 90 95 96 95 rmse c 1.7 2.1 2.0 1.6 1.0 1.0 1.0 1.1 1.0 1.3 1.4 1.7 svalbard airport—akseløya (2010–12) αa 0.973 0.985 0.919 0.879 1.083 1.059 0.878 1.115 1.100 1.179 1.166 1.072 ca −1.13 −0.92 −1.25 −0.95 0.62 1.10 2.36 0.28 −0.66 −1.28 −1.08 −1.16 ssr/sst b (%) 94 95 93 85 93 75 53 77 90 93 97 93 rmse c 1.6 1.6 1.7 1.8 0.9 1.0 1.1 1.1 0.9 1.1 1.0 1.5 svalbard airport—crozierpynten (2010–12) αa 0.835 0.915 0.863 0.766 0.621 0.447 0.447 0.447 0.707 0.995 0.881 0.753 ca −0.64 −0.56 0.45 −0.44 0.10 4.06 4.06 4.06 2.32 0.67 0.10 −0.41 ssr/sst b (%) 87 66 89 73 60 36 36 36 60 77 78 85 rmse c 3.0 4.2 2.3 2.4 1.7 1.7d 1.7d 1.7d 1.4 2.1 2.7 2.2 svalbard airport—svarttangen (2010–12) αa 0.977 0.893 0.764 0.892 0.860 0.771 0.771 0.771 1.157 1.208 0.967 0.879 ca −0.53 −1.16 −1.08 0.12 0.87 3.20 3.20 3.20 −0.33 −0.89 −1.19 −1.03 ssr/sst b (%) 92 86 88 80 62 33 33 33 75 91 91 90 rmse c 2.4 2.7 2.5 2.1 1.7 1.8d 1.8d 1.8d 1.1 1.3 1.8 1.8 svalbard airport—isfjord radio αa 1.218 1.231 1.263 1.226 1.207 1.193 1.226 1.132 1.156 1.195 1.207 1.205 ca −0.56 −0.41 −0.27 −0.37 0.09 −0.09 −0.33 −0.19 −0.80 −0.89 −0.59 −0.61 ssr/sst b (%) 96 96 95 94 97 89 79 85 93 96 96 96 rmse c 1.6 1.7 1.7 1.4 0.7 0.8 1.0 0.8 0.9 1.0 1.1 1.5 svalbard airport—sørkappøya (2010–12) αa 1.020 1.038 0.984 0.920 1.050 0.740 0.370 0.600 1.234 1.290 1.240 1.043 ca −1.71 −1.64 −1.84 −1.27 0.84 3.00 5.83 3.73 −0.81 −1.88 −1.97 −2.14 ssr/sst b (%) 90 86 88 84 83 34 1 13 73 86 90 84 rmse c 2.1 2.6 2.1 2.8 1.4 1.6 1.5 2.0 1.4 1.4 1.6 2.3 bsvalbard airport—grid point 78°n, 16°e αa 2.327 2.666 2.212 2.334 1.492 0.751 0.679 0.630 1.047 1.388 1.986 2.272 c a −1.00 −0.18 −3.72 −2.25 −2.03 1.39 3.41 3.08 −0.09 −1.55 −0.72 −0.18 ssr/sst b (%) 70 60 56 55 44 34 40 41 73 82 76 73 acoefficients in the regression equation (eqns. 2, 3). bthe regression ssr divided by the sst in % (variance accounted for by regression). croot mean square of the residuals. dregressions with data for the entire summer season june–august. evaluation of the uncertainty and variance to evaluate the results, we used two measures (table 2). the rmse is often used as a measure for uncertainties in a regression model. another measure—the ssr/sst ratio—tells how much of the variance is accounted for by the regression. it turns out that the quality of the regression varies throughout the year. winter, spring and autumn. the uncertainty is largest in these seasons, rmse amounts to 1–2 °c for most of the stations, but it is less than 1 °c for the longyearbyen station, which lies only 4 km from the measuring site at the airport. for the stations outside western spitsbergen such as sørkappøya, crozierpynten and svarttangen the rmse exceeds 2 °c for many of the months. the variance accounted for by the regression is as high as about 95% for most of the stations but is less for the three stations already mentioned lying outside western spitsbergen. the modelled temperatures based on longyearbyen, however, are remarkable: the regression accounts for 99% of the variance in january, february, march, october and november. summer. the rmse is low for june, july and august. this is due to very low variability in the arctic summer temperature rather than because of the quality of the model. this is seen by studying the ssr/sst ratio, which for many of the stations is about 80–90%. for sørkappøya, crozierpynten and svarttangen, however, the ssr/sst ratios are very low. because such a small part of the variance is accounted for by the regression we have omitted the summer months for these particular stations in the composite series of daily means. after calculating and applying regression equations, the svalbard airport series is available as predictions in the period september 1898–july 1975, and as observations in the period august 1975–december 2018. evaluation of maxima and minima the series is shown in fig. 3 for both annual and seasonal values. looking first at the individual means (annual or seasonal), the lowest temperatures are usually found in the early part of the series, except for autumn, in which there is a cluster of cold years in the late 1960s. the highest temperatures are found in the most recent years; for example, seven very warm years occurred consecutively in the period 2012–18. among these, 2016 stands out as being particularly warm; it was in fact the warmest year in the whole composite series and had an annual mean temperature of 0 °c. this year also includes the highest mean spring temperature. fig. 3 temperature (°c), vertical axis for the composite svalbard airport series during the period september 1898–december 2018 for winter (djf), spring (mam), summer (jja), autumn (son) and annual means (year). individual years (dots) are filtered by a gaussian low-pass filter (curve) with a standard deviation of three years in its distribution, corresponding to a rectangular filter of about 10 years. (the ends of the curves are not significant. for the last year, 2018, 38% of the weights will lie on unknown future observations; for the sixth last year, 2012, it is only 5%.) orange dots represent mean temperatures for the summer season; these values have larger uncertainty than the other means. the summer of 1922 is an example of a high temperature relatively early in the series, and the summer of 1899 is remarkably warm. thirty percent of the data for the 1899 summer is from reanalysis and 70% from regression with akseløya. the part from akseløya does not have an uncertainty greater than for most of the series, so even with the 30% included from the reanalysis, the 1899 summer mean is considered quite reliable. however, looking at the whole series, all warm extremes (annual as well as seasonal) are found in the 21st century. decadal variations decadal variations were studied by low-pass gaussian filtering (fig. 3). a striking feature is the warming from the 1910s to the 1930s known as the early 20th century warming, which leads up to the local maxima in the 1930s and the 1950s. they were particularly warm both for annual and seasonal mean temperature. another striking feature is the warming of the svalbard climate in the latest two decades. the present warm svalbard -airport climate exceeds the temperature of the 1930s and 1950s by at least 2 °c for annual values. the most pronounced cold decade was that of the 1910s, which was colder than any other decade in the whole series, and in all seasons. another cold phase peaked in the 1960s. regime shifts the decadal variations illustrated by gaussian filtering, might lead us to presume that the svalbard temperature climate shifts between different regimes. in the work of nordli et al. (2014), for the period 1899–2012, six regimes were detected by the rodionov test (rodionov 2004) for the annual means, and five regimes were detected for the winter (djf) means. we performed exactly the same testing on the new data set for the 1899–2012 period and got the same results. slightly reducing the influence of outliers by using the huber tuning constant (huber 1981; fig. 4) made the shortest regimes (those in the 1910s and 1960s) disappear, so the number of regimes was reduced to four both for the annual series and for the winter season series. the series begins with a cold regime, the next is warm, then cold again and the last one is warm. for annual means the last cold regime is 1.0 °c warmer than the first cold regime, and the last warm regime is 1.7 °c warmer than the first warm regime. this is a consequence of a trend towards higher temperature for the entire series. fig. 4 regime shifts of the extended svalbard airport temperature series detected by using the rodionov test for annual and winter season means in the period 1899–2018. the shifts were determined by means of student’s test with significance level p = 0.05, and the cut-off length was set to 10 years. shifts were detected after data prewhitening procedure by using the ip4 method (see rodionov 2006) but original data are plotted. huber’s tuning constant was set to 2. trends and statistical significance the svalbard airport series shows large positive linear trends in all seasons (table 3). they are greatest in winter and spring with an increase of 0.43 and 0.42 °c per decade, respectively, compared to 0.13 °c in summer. the trend in winter is much steeper than in summer but the variability is also much larger. compared to the other seasons the winter has the steepest trend, but the lowest signal-to-noise ratio, that is, trend divided by standard deviation (table 3). the trend for annual means amounts to 0.32 °c per decade. for individual months, the trend is largest in february and smallest in june: 0.65 and 0.10 °c, respectively, per decade (not shown). table 3 annual and seasonal linear trends and signal to noise ratio (trend divided by standard deviation) in the svalbard airport homogenized series for winter (djf), spring (mam), summer (jja) and autumn (son) for the whole series september 1898–december 2018 and for the period january 1991–december 2018. all trends are significant at the 0.05 level. annual djf mam jja son whole series 1898.09–2018.12 trend (°c) per decade 0.32 0.43 0.42 0.13 0.30 signal to noise ratio 1.9 1.3 1.8 1.8 1.6 period 1991.01–2018.12 trend (°c) per decade 1.66 3.19 1.05 0.66 1.65 signal to noise ratio 3.6 8.4 4.6 1.7 4.4 for the entire period 1899–2018 the temperature has increased by 3.8 °c for annual means, which might be seen as a manifestation of arctic amplification. for the homogenized oslo series (nordli et al. 2015), for example, the temperature change for the same period is 1.3 °c, whereas the global mean is about 1 °c. the significance of the trends was tested by making use of the mann–kendall rank test with 1% significance level. the trends were significant for annual means as well as for seasonal means in the period 1899 (for autumn 1898)–2018. trends in annual and seasonal means (table 3) can be compared with the corresponding table 4 in the work of nordli et al. (2014). in all seasons both the trends and the signal-to-noise ratio have increased. for the annual mean, the trend is now 0.32 °c per decade compared to 0.26 °c. the reason must be either the extra data at the end of the series or the recent digitization and improved data control. we tested this by using the new data set but omitted the six new years (2013–18). the annual trend (1899–2012) was then the same for the new data set as for the old one, 0.26 °c. for winter, the trend increased by 0.02 °c and in spring it decreased by −0.02 °c, whereas there was no change for summer and autumn. table 4 definitions of terms used in threshold statistics. terms definitions gd number of growing days, t > 5 °c in may–sep td number of thawing days, t > 0 °c in may–sep md number of melt days, t > 0 °c in oct–apr fd number of freeze days, t < 0 °c in oct–apr annual growing degree-days sum air thawing index degree-days sum positive degree-days sum air freezing index degree-days sum ti mean temperature on day i and n is the number of days n number of days we may conclude that the increased trends are not generated by correction of the old data, but by the increased length of the series. adding six years of data to the original data set lengthened the data set by only 5%. it may be surprising that this could influence the trends so much, but five of the six years were particularly warm; they are among the seven warmest years in the entire series. recent trends in the spitsbergen temperature climate seem to be very steep as depicted in fig. 3. this has motivated the decision to conduct a study spanning the latest 28 years (1991–2018), which will be included in the next standard normal period (1991–2020). for all seasons the trends during those years are steeper than for the whole series (table 3). in particular, the linear trend for the winter season is very steep, amounting to 3.2°/decade. for all seasons, but summer, the signal to noise values are also more pronounced in the recent period compared to the whole series. threshold statistics the new data set of mean daily temperatures allows us to present long-term threshold statistics for svalbard, definitions (table 4) and results (table 5, fig. 5). these provide additional information about the svalbard climate, which may prove useful for biologists and engineers, particularly for thresholds near zero. figure 5a shows tremendous changes during the last three decades for the number of days per year warmer than the thresholds 0 and 5 °c and also for days colder than the thresholds −10 and −20 °c. the 1910s had 26 more days below −20 °c compared to the 1961–1990 normal, while the period 1991–2018 had 27 fewer days compared to the same period. in 2014, 2016 and 2018 there were no days colder than −20 °c. table 5 threshold statistics for the recent period 1991–2018 compared to the standard normal period 1961–1990. linear trends in the recent period are also given. threshold/index period1961–1990 period 1991–2018 anomaly (days or degree-days) anomaly (%) trend 1991–2018 (days or degree-days/decade) t > 5 (°c) 37 59 22 59 14 t > 0 (°c) 118 142 25 21 18 t < −10 (°c) 131 89 −42 −32 −25 t < −20 (°c) 43 16 −27 −62 −12 gd 37 58 22 59 14 td 107 122 16 15 10 md 11 20 9 79 8 fd 201 192 −8 −4 −8 gdd 68 123 55 81 34 ati 442 595 153 35 90 pdd 20 38 18 94 20 afi 2707 1947 −760 −28 −442 fig. 5 long-term daily mean air temperature (t) variability given as anomalies from the 1961–1990 standard normal period. all series are also filtered with a 10-year gaussian filter. the definitions of gd, td, md, fd, gdd, ati, pdd and afi are given in table 4. long-term variability in gd impacts plants’ and animals’ activity and growth, which in the arctic region may start as soon as snow melting has taken place. thus, both a threshold above 0 °c (td) and the conventional 5 °c (gd) are used for the may–september season (fig. 5b). the numbers of td and gd have both increased in recent times. the warming escalated during the period 1991–2018. the linear trend for 1991–2018 was as strong as 10 days/decade and 14 days/decade for td and gd, respectively (table 5). warm winter spells have been reported more frequently in svalbard in recent years (vikhamar-schuler et al. 2016; peeters et al. 2019). following the work of vikhamar-schuler et al. (2016), the long-term variability in the number of md (fig. 5b) is a useful measure to evaluate changes in the frequency of such winter-warming events in svalbard. they were also frequent in the 1930s and 1950s and not nearly as frequent as in the latest decades. consistent with the increase of md, a decrease in fd is also observed. degree-day sums are the sum of the temperatures of the days with daily mean temperatures above or below certain thresholds; so, they are a measure of not only the duration of such events but also their magnitude. the ati is used in permafrost engineering and is a basis for engineering design and for estimations of active layer thickness over the permafrost (instanes 2016). the ati is a measure of both magnitude and duration of the above 0 °c daily mean temperature during the summer season each year. likewise, the gdd measures magnitude and duration of daily mean temperature values above 5 °c during may to september. there has been a large increase in the gdd and ati in the period 1991–2018, amounting to an increase of 81 and 35% compared to the 1961–90 standard normal (table 5). to evaluate the intensity of warm events in the cold season spanning october–april, the pdd is used (fig. 5c, table 5). in the period 1991–2018, pdd has increased by 94% compared to the 1961–90 normal. the afi is a measure of the magnitude and duration of below 0 °c temperature events during the winter season each year. the results show that the mean afi for svalbard airport has decreased considerably since the late 1980s, the linear trend in the period 1991–2018 amounts to −442 degree-days/decade. discussion improving the series by reducing uncertainty and adding more data the methods that generated the first edition of the composite svalbard airport series have also been used in the present study. the original series had only monthly resolution, but the monthly values were in most cases generated by taking the arithmetic means of daily series. therefore, in principle, there should be no differences between the old and new data set of monthly means. however, digitization of the longyearbyen data series, the established overlapping periods between isfjord radio and svalbard airport, and the longer overlapping periods with akseløya and sørkappøya have led to some changes (see the metadata subsection for details). those metadata changes affect the composite series only before 1948. however, for the annual mean of all years in the period 1898–1947 there are no differences. for the mean temperature of individual months in that period, only april and december are different, but not by more than 0.1 °c. this does not mean that the recent corrections of the old data sets are not important. in the early part of the composite series, there are a few monthly means that have changed a lot (see the difference between the new and old svalbard airport composite series in supplementary table s3). are the regression equations biased? akseløya, sørkappøya, svarttangen and crozierpynten were awake research project stations intended for operation during two years, from summer 2010 to summer 2012. the regression equations for the svalbard airport series were performed with daily means grouped by months, so the number of data points in the regressions was only about 60. fortunately, axeløya and sørkappøya were turned into permanent stations in met norway’s operational network. this has by now increased the number of data points in the regression to about 250 for each month. this increased the significance of the regressions where these two stations were involved, that is, in parts of the 1898–1911 time interval. another question that should be addressed is the risk for biased results when regression equations are developed in the present svalbard climate for reconstruction of the historical climate. if the local climate has changed in the same way at svalbard airport as at the local stations, the method should be unbiased. this is assumed when relative homogeneity tests are used (e.g., nordli et al. 2015). one possible reason for biased regressions for the composite series is that the ice cover could react differently on the recent temperature increase at spitsbergen. we know that isfjorden has had very little ice cover in the 21st century and that the svalbard airport series has greater temperature trends than most other neighbouring series (gjelten et al. 2016; isaksen et al. 2016). if the ice cover has diminished less at the local station than at the airport, the regressed temperature at the airport could be too high in the period 1898–1911. the trend back in time to the beginning of the composite series could then be too weak. however, in that period four local stations are used; so biases, if any, should vary by station within the period. with help of data from isfjord radio we performed a case study by comparing regression equations based on the recent short interval september 2014–december 2018, with the intervals based on historical data (supplementary table s4). when used for the reconstruction of the composite series, the estimates based on the recent data differed only slightly from those based on the historical data set. the method used seems to be robust for changing climate. less model skill for summer observations and reanalysis data the model did not infer summer temperatures as well as temperatures for the other seasons, as indicated by the part of the variance accounted for by the regression (table 2). the uncertainties are particularly great for the series from outside western spitsbergen: crozierpynten and svarttangen. (the same is also true for sørkappøya, but no summer temperature from this station is included in the svalbard airport composite series.) we keep the data from crozierpynten and svarttangen in the composite series of monthly means but omit them in the corresponding series of daily means because of the large uncertainty. before 1911 and during the second world war there are some missing observations in svalbard. the monthly values were interpolated by data from reanalysis (compo et al. 2011) but the model skill is poor (table 2). again, we keep the monthly means based on reanalysis but the large uncertainty prompts us to omit the reanalysis data in the series of daily means. comparing the composite svalbard airport temperature series with the nearest neighbouring series svalbard airport’s neighbouring long-term series are bjørnøya (74°31’ n, 19°00’ e), to the south of spitsbergen, vardø (70°22’ n, 31°6’ e), in north-eastern continental norway, jan mayen (70°56’ n, 8°40’ w), between iceland and svalbard and malye karmakuly (72°22’ n, 52°42’ e), in the russian archipelago of novaya zemlya. these meteorological stations are situated in the north atlantic and barents sea. all of them are positively correlated with the svalbard airport series for annual and seasonal mean temperature (przybylak 1997, 2016) during the years when they overlap with the svalbard airport series. with correlations of about 0.9 for annual values and for winter, spring and autumn, the svalbard series is most closely in tandem with the bjørnøya series than the other stations (supplementary table s5). this is also true for post-1950 sub-periods but not for the warm period of 1921–50, where correlations are somewhat weaker. the correlations for annual values during the period 1921–2018 are 0.94 for bjørnøya, 0.81 for jan mayen, 0.75 for vardø and 0.66 for malye karmakuly. different sub-periods have seen different temperature trends in the svalbard airport series (fig. 3). the warming in the early 20th century and the following cold period are striking examples. the four other stations in the area also follow this pattern but the magnitudes of the trends are different (supplementary table s6). svalbard airport and malye karmakuly have had the strongest temperature decrease during the period 1951–80 but also the strongest increase in the recent 1991–2018 period (supplementary table s6). finally, we can conclude that the svalbard -airport series exhibits a stronger trend during the common data period, 1921–2018, than the other four stations. the recent warming of svalbard and implications from long-term threshold statistics the reason for the large decadal variations in air temperature in svalbard might to a certain extent be governed by temperature variability in the north atlantic ocean, such as the atlantic multidecadal oscillation (hanssen-bauer et al. 2019 and references therein). it is supposed that this is the main reason for the detected regime shifts in the svalbard airport series. the inflow of atlantic water to the svalbard region was particularly high after around 2000. this is consistent with a detected shift to high temperature in 1999 for annual temperature and in 2005 for the winter season. the recent increase in surface air temperature in svalbard is the greatest observed in europe (nordli et al. 2014) and among the most severe in the arctic during the last three decades (isaksen et al. 2016). since 1991, the rate of warming at svalbard airport has been 1.7 °c/decade, based on linear trend analysis (table 3). this amounts to more than twice the arctic average (0.8 °c/decade, north of 66°n (noaa-esrl 2019) and is about seven times the global average (0.2 °c/decade), based on the latest gistemp data (gistemp team 2019; lenssen et al. 2019). in a recent paper, przybylak & wyszyński (2020) inferred that the annual mean temperature for the high arctic (see definition in their figure 1) has increased by 1.6 °c in the period 1996–2015 compared with the reference period 1951–1990. for svalbard airport, the comparable increase amounts to 2.5 °c, that is, 0.9 °c (56%) higher than for the high arctic. mechanisms for arctic amplification are still debated, but feedbacks from the loss of sea ice form one of the major components (overland et al. 2018; ipcc 2019). in mid-winter, sea ice normally covers most of the arctic ocean and the northern areas of the five marginal arctic seas. the exceptions in recent years have been the svalbard area and the northern barents sea, which add to the trend towards more open water in winter in this region. these changes are a key to why this region is warming faster than the rest of the arctic. in svalbard, the greatest contribution to the recent warming is associated with wintertime cyclonic air advection from the east–north-east, related to a low-pressure system moving into the barents sea (isaksen et al. 2016). these air masses are strongly modified when they flow over open ocean. thus, at least parts of the atmospheric warming observed in svalbard are driven by heat exchange from declining sea ice in the barents sea and the region north of svalbard. svalbard airport’s proximity to isfjorden might be another factor for its severe temperature changes (gjelten et al. 2016; isaksen et al. 2016). the fjord has recently become more influenced by the intrusion of warm atlantic water from the west spitsbergen current (cottier et al. 2007; nilsen et al. 2008), which plays a decisive role for the sea-ice cover in the fjord and thereby increases heat exchange from the larger open water areas even during winter. although not as severe as the air advection from the east–north-east, a general warming is seen for all atmospheric circulation types in svalbard (isaksen et al. 2016), suggesting additional contributions from large-scale mechanisms, such as general background warming (bindoff et al. 2013; fyfe et al. 2013; pithan & mauritsen 2014; navarro et al. 2016) and higher sea-surface temperatures (dmitrenko et al. 2014; carmack 2015). according to a new study conducted by lind et al. (2018) the increased sea-surface and ocean temperatures in the northern barents sea are linked to a recent decline in sea-ice import and a corresponding loss in surface freshwater, leading to weakened ocean stratification, enhanced vertical mixing and increased upward fluxes of heat and salt that prevent sea-ice formation. the new data set of mean daily temperatures allows us to present long-term threshold statistics for svalbard (table 5, fig. 5). we anticipate that this additional information about svalbard’s climate will be of value to biologists and engineers, particularly for thresholds near zero. the combination of decreasing afi and increasing ati is a clear signal of a changing climate, which may affect the stability of existing building foundations on permafrost in svalbard (instanes 2016). these events cause ecological disturbance (peeters et al. 2019); for example, ground-ice formation due to winter rain or melting snow prevents ungulates from grazing (hansen et al. 2014). they also pose challenges for human society and the archipelago’s infrastructure, particularly on account of rising soil temperatures (hansen et al. 2014). conclusions the svalbard airport composite time series of mean monthly temperature has been widely used by scientists in a variety of disciplines. the present study increases the resolution from a monthly to daily basis, further contributing to scientific studies of svalbard and the wider arctic. a svalbard series on daily resolution opens up for calculating threshold statistics that is necessary for, for example, engineering design and biological research on the islands. the large changes in the svalbard climate during the last 30 years, which by this long-term series sets in a historical context, makes this of paramount interest. our study supports the concept that the svalbard climate responds to increasing greenhouse gases in the atmosphere with a series of regime shifts. these are governed by a combination of natural variability and a set of feedbacks that amplify warming, especially related to changing sea-surface temperature and sea-ice variations. four shifts were detected, indicating that the temperature was alternating between warm and cold phases. alternatively, the variations in the series can be interpreted as variations on a multi-decadal scale, consisting of positive and negative local trends. for the whole series, 1899–2018, the linear increase was 3.8°c. that is about 3.5 times more than for the global mean temperature during the same period. acknowledgements the authors acknowledge olav p. amundgård for digitizing the previously missing protocols from the longyearbyen station. references amap (arctic monitoring and assessment programme) 2017. snow, water, ice and permafrost in the arctic (swipa) 2017. oslo: arctic monitoring and assessment programme. alekseev g., glok n. & smirnov a. 2016. an assessment of the relationship between changes of sea ice extent and climate in the arctic. international journal of climatology 36, 3407–3412, doi: 10.1002/joc.4550. alexandersson h. 1986. a homogeneity test applied to precipitation data. journal of climatology 6, 661–675, doi: 10.1002/joc.3370060607. bacc (baltex assessment of climate change for the baltic sea basin) author team 2008. assessment of climate change for the baltic sea basin. berlin: springer. bindoff n.l., stott p.a., achutarao k.m., allen m.r., gillett n., gutzler d., hansingo k., hegerl g., hu y., jain s., mokhov i.i., overland j., perlwitz j., sebbari r. & zhang x. 2013. detection and attribution of climate change: from global to regional. in t.f. stocker et al. (eds.): climate change 2013: the physical science basis. contribution of working group i to the fifth assessment report of the intergovernmental panel on climate change. pp. 867–952. cambridge: cambridge university press. carmack e. 2015. toward quantifying the increasing role of oceanic heat in sea ice loss in the new arctic. bulletin of the american meteorological society 96, 2079–2105, doi: 10.1175/bams-d-13-00177.1. compo g.p., whitaker j.s., sardeshmukh p.d., matsui n., allan r.j., yin x., gleason b.e., vose r.s., rutledge g., bessemoulin p., brönnimann s., brunet m., crouthamel r.i., grant a.n., groisman p.y., jones p.d., kruk m.c., kruger a.c., marshall g.j., maugeri m., mok h.y., nordli ø., ross t.f., trigo r.m., wang x.l., woodruff s.d. & worley s.j. 2011. the twentieth century reanalysis project. quarterly journal of the royal meteorological society 137, 1–28, doi: 10.1002/qj.776. corti s., molteni f. & palmer t.n. 1999. signature of recent climate change in frequencies of natural atmospheric circulation regimes. nature 398, 799–802, doi: 10.1038/19745. cottier f.r., nilsen f., inall m.e., gerland s., tverberg v. & svendsen h. 2007. wintertime warming of an arctic shelf in response to large-scale atmospheric circulation. geophysical research letters 34, l10607, doi: 10.1029/2007gl029948. descamps s., aars j., fuglei e., kovacs k.m., lydersen c., pavlova o., pedersen å.ø., ravolainen v. & strøm h. 2017. climate change impacts on wildlife in a high arctic archipelago—svalbard, norway. global change biology 23, 490–502, doi: 10.1111/gcb.13381. dmitrenko i.a., kirillov s.a., serra n., koldunov n.v., ivanov v.v., scauer u., polyakov i.v., barber d., janout m., lien v.s., makhotin m. & aksenov y. 2014. heat loss from the atlantic water layer in the northern kara sea: causes and consequences. ocean science 10, 719–730, doi: 10.5194/os-10-719-2014. ewertowski m.w., evans d.j.a., roberts d.h., tomczyk a.m., ewertowski w. & pleksot k. 2019. quantification of historical landscape change on the foreland of a receding polythermal glacier, hørbyebreen, svalbard. geomorphology 325, 40–54, doi: 10.1016/j.geomorph.2018.09.027. fyfe j.c., von salzen k, gillett n.p., arora v.k., flato g.m. & mcconnell j.r. 2013. one hundred years of arctic surface temperature variation due to anthropogenic influence. scientific reports 3, article no. 2645, doi: 10.1038/srep02645. gistemp team 2019. giss surface temperature analysis (gistemp). nasa goddard institute for space studies. data set accessed on the internet at data.giss.nasa.gov/-gistemp/ on 18 november 2019. gjelten h.m., nordli ø., isaksen k., førland e.j., sviashchennikov p.n., wyszynski p., prokhorova u.v., przybylak r., ivanov b.v. & urazgildeeva a.v. 2016. air temperature variations and gradients along the coast and fjords of western spitsbergen. polar research 35, article no. 29878, doi: 10.3402/polar.v35.29878. graversen r.g., langen p.l. & mauritsen t. 2014. polar amplification in ccsm4: contributions from the lapse rate and surface albedo feedbacks. journal of climate 27, 4433–4450, doi: 10.1175/jcli-d-13-00551.1. hamilton c.d., kovacs k.m. & lydersen c. 2018. individual variability in diving, movement and activity patterns of adult bearded seals in svalbard, norway. scientific reports 8, article no. 16988, doi: 10.1038/s41598-018-35306-6. hansen b.b., isaksen k., benestad r., kohler j., pedersen å.ø., loe l.e., coulson s.j., larsen j.o. & varpe ø. 2014. warmer and wetter winters: characteristics and implications of an extreme weather event in the high arctic. environmental research letters 9, article no. 114021, doi: 10.1088/1748-9326/9/11/114021. hanssen-bauer i., førland e.j., hisdal h., mayer s., sandø a.b. & sorteberg b. 2019. climate in svalbard 2100—a knowledge base for climate adaptation. nccs report 1. oslo: norwegian centre for climate services. hegerl g.c., brönnimann s., schurer a. & cowan t. 2018. the early 20th century warming: anomalies, causes, and consequences. wiley interdisciplinary reviews climate change 9, e522, doi: 10.1002/wcc.522. huber p.j. 1981. robust statistics. new york: john wiley. instanes a. 2016. incorporating climate warming scenarios in coastal permafrost engineering design—case studies from svalbard and northwest russia. cold regions science and technology 131, 76–87, doi: 10.1016/j.coldregions.2016.09.004. ipcc (intergovernmental panel on climate change) 2019. summary for policymakers. in h.-o. pörtner et al. (eds.): ipcc special report on the ocean and cryosphere in a changing climate. accessed on the internet at https://www.ipcc.ch/srocc/chapter/summary-for-policymakers/ on 25 march 2020 isaksen k., nordli ø., førland e.j., lupikasza e., eastwood s. & niedzwiedz t. 2016. recent warming on spitsbergen—influence of atmospheric circulation and sea ice cover. journal of geophysical research—atmospheres 121, 11913–11931, doi: 10.1002/2016jd025606. lenssen n., schmidt g., hansen j., menne m., persin a., ruedy r. & zyss d. 2019. improvements in the gistemp uncertainty model. journal of geophysical research—atmospheres 124, 6307–6326, doi: 10.1029/2018jd029522. lind s., ingvaldsen r.b. & furevik t. 2018. arctic warming hotspot in the northern barents sea linked to declining sea-ice import. nature climate change 8, 634–639, doi: 10.1038/s41558-018-0205-y. łupikasza e.b. & niedźwiedź t. 2019. the influence of mesoscale atmospheric circulation on spitsbergen air temperature in periods of arctic warming and cooling. journal of geophysical research—atmospheres 124, 5233–5250, doi: 10.1029/2018jd029443. muckenhuber s., nilsen f., korosov a. & sandven s. 2016. sea ice cover in isfjorden and hornsund, svalbard (2000–2014) from remote sensing data. the cryosphere 10, 149–158, doi: 10.5194/tc-10-149-2016. navarro j.c., varma v., riipinen i., seland ø., kirkevåg a., struthers h., iversen t., hansson h.-c. & ekman a.m.l. 2016. amplification of arctic warming by past air pollution reductions in europe. nature geoscience 9, 277–281, doi: 10.1038/ngeo2673. nilsen f., cottier r., skogseth r. & mattsson s. 2008. fjord–shelf exchanges controlled by ice and brine production: the interannual variation of atlantic water in isfjorden, svalbard. continental shelf research 28, 1838–1853, doi: 10.1016/j.csr.2008.04.015. noaa-esrl (national oceanic and atmospheric administration earth system research laboratory) 2019. ncep/ncar reanalysis. physical sciences division, boulder colorado. data set accessed on the internet at https://www.google.com/search?q=0.8%c2%b0c%2​fdecade​%2c+north+of+66%c2%b0n+(noaa-esrl+2019&rlz=1c1gcea_enno835no835&oq=0.8%c2%b0c%2fdecade%2c+north+of+66%c2%b0n+(noaa​-esrl+2019&aqs=chrome..69i57j69i58.​5381j0j7​&sourceid=chrome&ie=utf-8 on 4 april 2020 nordli ø., hestmark g., benestad r.e. & isaksen k. 2015. the oslo temperature series 1837–2012: homogeneity testing and temperature analysis. international journal of climatology 35, 3486–3504, doi: 10.1002/joc.4223. nordli ø., przybylak r., ogilvie a.e.j. & isaksen k. 2014. long-term temperature trends and variability on spitsbergen: the extended svalbard airport temperature series, 1898–2012. polar research 33, article no. 21349, doi: 10.3402/polar.v33.21349. osmont d., wendl i.a., schmidely l., sigl m., vega c.p., isaksson e. & schwikowski m. 2018. an 800-year high-resolution black carbon ice core record from lomonosovfonna, svalbard. atmospheric chemistry and physics 18, 12777–12795, doi: 10.5194/acp-18-12777-2018. overland j.e., hanna e., hanssen-bauer i., kim s.-j., walsh j.e., wang m., bhatt u.s. & thoman r.l. 2018. arctic report card 2018. accessed on the internet at www.arctic.noaa.gov/report-card on 25 march 2020. overland j.e. & wang m. 2010. large-scale atmospheric circulation changes are associated with the recent loss of arctic sea ice. tellus a 62, 1–9, doi: 10.1111/j.1600-0870.2009.00421.x. overland j.e., wood k. & wang m. 2011. warm arctic-cold continents: climate impacts of the newly open arctic sea. polar research 30, article no. 15787, doi: 10.3402/polar.v30i0.15787. overland j.e. & serreze m.c. 2012. advances in arctic atmospheric research. in p. lemke & h.-w. jacobi (eds.): arctic climate change. the acsys decade and beyond. pp. 11–26. dordrecht: springer. park d.-s.r., lee s. & feldstein s.b. 2015. attribution of the recent winter sea ice decline over the atlantic sector of the arctic ocean. journal of climate 28, 4027–4033, doi: 10.1175/jcli-d-15-0042.1. peeters b., pedersen å.ø., loe l.e., isaksen k., veiberg v., stien a., kohler j., gallet j.-c., aanes r. & hansen b.b. 2019. spatiotemporal patterns of rain-on-snow and basal ice in high arctic svalbard: detection of a climate-cryosphere regime shift. environmental research letters 14, article no. 015002, doi: 10.1088/1748-9326/aaefb3. pithan f. & mauritsen t. 2014. arctic amplification dominated by temperature feedbacks in contemporary climate models. nature geoscience 7, 181–184, doi: 10.1038/ngeo2071. pramanik a., van pelt w., kohler j. & schuler t.v. 2018. simulating climatic mass balance, seasonal snow development and associated freshwater runoff in the kongsfjord basin, svalbard (1980–2016). journal of glaciology 64, 943–956, doi: 10.1017/jog.2018.80. przybylak r. 1997. spatial variation of air temperature in the arctic in 1951–1990. polish polar research 18, 41–63. przybylak r. 2016. the climate of the arctic. 2nd edn. dordrecht: springer, doi: 10.1007/978-3-319-21696-6. przybylak r. & wyszyński p. 2020. air temperature changes in the arctic in the period 1951–2015 in the light of observational and reanalysis data. theoretical and applied climatology 139, 75–94, doi: 10.1007/s00704-019-02952-3. rodionov s.n. 2004. a sequential algorithm for testing climate regime shifts. geophysical research letters 31, l0924, doi: 10.1029/2004gl019448. rodionov s.n. 2006. use of prewhitening in climate regime shift detection. geophysical research letters 33, l12707, doi: 10.1029/2006gl025904. serreze m.c., barrett a.p. & cassano j.j. 2011. circulation and surface controls on the lower tropospheric air temperature field of the arctic, journal of geophysical research—atmospheres 116, d07104, doi: 10.1029/2010jd015127. stuecker m.f, bitz c.m., armour k.c., proistosescu c., kang s.m., xie s.-p., kim d., mcgregor s., zhang w., zhao s., cai w., dong y. & jin f.-f. 2018. polar amplification dominated by local forcing and feedbacks. nature climate change 8, 1076–1081, doi: 10.1038/s41558-018-0339-y. vikhamar-schuler d., isaksen k., haugen j.e., tømmervik h., luks b., schuler t.v. & bjerke j.w. 2016. changes in winter warming events in the nordic arctic region. journal of climate 29, 6223–6244, doi: 10.1175/jcli-d-15-0763.1. wilks d.s. 1995. statistical methods in the atmospheric science. an introduction. amsterdam: academic press. woelders l., lenaerts j.t.m., hagemans k., akkerman k., van hoof t.b. & hoek w.z. 2018. recent climate warming drives ecological change in a remote high-arctic lake. scientific reports 8, article no. 6858, doi: 10.1038/s41598-018-25148-7. notes on the ecology and physiology of the antarctic oribatid mite maudheimia wilsoni* lauritz sbmme, alexander str0mme and karl erik zachariassen s0mme. l . , str~imme, a . & zachariassen, k . e. 1993: notes on the ecology and physiology of the antarctic mite maudheimia wilsoni. polar research 12(1), 21-25. the oribatid mite maudheimia wiboni dalenius was found to be numerous on the underside of stones at jutulsessen (72'5, 3"e) in dronning maud land, antarctica. daily temperature fluctuations of the microhahitat from as high as 19°c and to as low as -17°c were observed during the austral summer. optimal activity of the mites occurred at 10°c. even in january the mean supercooling point of adult mites was as low as -30.8 2 4.x. haemolymph osmolality ranged from 500 to 800mosmol and thermal hystersis freezing points from -4.7 to -6.1"c. adult mites had a mean water content of 43.6% and a water loss rate of 0.12 pg h-' at 15°c and 10% relative humidity. lauritz sflmrne, institute of biology, university of oslo, p . o . box i050 blindern, n-0316 oslo, norway; alex strflmme, department of ecotoxicology, allforsk, n-7055 dragvoll, norway; karl erik zach ariassen, institute of zoology, university of trondheim, n-7055 dragvoll, norway. introduction norwegian antarctic research expedition (nare) 1989/90 from 13 january to 15 february only three species of orabatid mites have been 1990. mites were collected in the vicinity recorded from the antarctic continent. maudheiof the norwegian station "troll,, (7200.7,s, north victoria land only, while alaskozetes antsessen. a survey of the botany of the area has arcticus (michael) is also widely distributed in been presented by engelskjon (1986). the maritime and subantarctic zones (wallwork of a small 1967). maudheimia wilsoni dalenius is endemic aspirator and kept in ml glass vials at tem ryan & watkins 1989). while a. antarcticus has used in the experiments within 48 hours after been the subject of numerous ecological and sampling. *lock 1991)7 very little is known about m . nymphal stages in the field. adult specimens only wilsoni. high densities of this species, however, were used for the present study, without sep have been reported from the robertskollen group aration of the sexes. was observed to be common in the jutulsessen a grant squirrel 1200 data logger. supercooling mites to a copper-constantan thermocouple by one of the present authors (a.s.). means of vaseline. the thermocouple was placed and lowered into a cold mixture made from crushed ice and cac12.6h20. scps were tered for 30 specimens at a cooling rate of approxi mately 1°c min-'. haemolymph osmolality and thermal hysteresis activity were measured in a clifton nanoliter osmometer as described by aunaas et al. (1983). some modifications of the procedure had to be that could be extracted from the mites. each mite mia perrouia has been reported from 2'32.3'e) (nor& polarinstitutt 1990) in jutul the mites were sampled by to western dronning maud land (samme 1986a; peratures ranging from 0 to -10°c. they were physiological studies 1984; 'omme ' adults were separated from larvae and the of 'ijnataks (ryan ' watkins 1989), and the mite temperature recordings were carried out with area, gjelsvikfje1ia, dronning maud land, by points (scps) were measured by attaching 5-7 the purpose o f the present study was to the and physiology of m . wilsoni inside three plastic tubes, one outside the other, in the jutulsessen area, especially with respect to local distribution, life-cycle and adaptations to the antarctic environment. material and methods the investigation was carried out during the expeditions 1976177. 1978179, 1984185 and i989 f 90. * publication no. i14 of the norwegian antarctic research made due to the of haemolymph 22 was embedded in a drop of liquid paraffin on a cover glass slide. subsequently, the mite was punctured with a needle and droplets of hae molymph were pulled out in the paraffin. the cover glass was placed on the peltier cell of the osmometer, and the melting and freezing of the droplets observed under a binocular microscope. in order to study the nutrition of the mites, the presence of microphyte flora in their surroundings was investigated. incrustations and coatings were scraped off from the stones and brought to oslo for closer examination. the activities of the mites at different tem peratures were studied by placing individual specimens at the bottom of glass capillary tubes which had been closed in one end. a ther mocouple was put into a similar capillary, and both capillaries were placed in a fixed position with their closed ends in a vial filled with water. the water served as a thermal buffer. the activity of the mites was studied at different temperatures and judged on a subjective scale. zero cor responded to no movements during a period of 30 seconds, 1 to small movements, 2 moderate movements, and 3 to quick movements of the legs. l. s@mme, a . str@mme & k . e . zachariassen 20 16 12 8 4 0 4 -8 -12 -16 results occurrence of the mites the main distribution of the m . wilsoni appeared to be restricted to grjotlia in the outer nw part of the jutulsessen mountain complex, but scattered specimens were found over the entire area, including the inner slopes of jutulsessen. the area is generally dry. during the expedition period precipitation was rarely observed, but drifting snow occasionally covered the ground for hours. the melting of this snow and melting of ice and larger deposits of snow from higher elevations are the only sources of ground humidity. the mites were found under rocks of different geological origin, shapes and sizes. they appeared, however, to prefer pelitic gneisses (yoshihide ohta, pen. comm.) with the approxi mate dimensions of 1 x 15 x 3cm. the sub stratum under the stones was mainly composed of relatively dry sand and gravel. the mites were found both as single individuals and in aggregations with up to 30 specimens. they appeared to be quite stationary on the underside a 1 + wi-1990 28/1.1990 1541-1990 x 05/2-1990 . 11/2-1990 i -20! ' 1 . 1 . i ' 1 . 1 . ' i ' i ' 1 ' ' . 0 2 4 6 8 10 12 14 16 i8 20 22 24 time (hours) fig. 1. temperature recordings from typical microhabitat for maudheimia wilsoni through 24 hours on 22 january and 5 february 1990 (filled symbols) and 4 a.m. and 4 p.m. on three additional days. of the stones. single mites were always adults, while the aggregations consisted of juveniles and adults. old cuticular cast-offs from nymphs were frequently observed in the aggregations. the air temperatures in the area varied between 6 and -22°c (winther 1990), but temperatures in the microhabitats of the mites could be con siderably higher. examples of dial temperature fluctuations are presented in fig. 1. during the expedition period this microhabitat was exposed to the sun for 10-12 hours. the highest observed temperature in the middle of january was 19°c but temperatures remained below 0°c for half of the day. in the middle of february temperatures did not exceed 0°c even during the warmest part of the day, which occurred around 4 p.m. nutrition the only visible plants in the area were different species of crustose lichens on rocks and stones, as well as scattered occurrences of the green alga prasiola on moist gravel. no macrophytes were observed under the stones. cultivation of organ isms from different substrates in the jutulsessen area revealed rich occurrences of diatomers, coc coide bacteria, protozoans, rotifers and 17 species of algae (olav skulberg, pers. comm.), some of which may be potential sources of nutrition for the mites. no growth of any organisms was observed from substratum collected close to the mites. the ecology and physiology of the antarctic oribatid mite maudheimia wilsoni 23 " -5 0 5 10 15 20 25 temperature ('c) fig. 2. levels of activityof adult maudheimia wilsoni at different temperatures, mean ( 2 s d ) are presented (n = 5). see text for further explanation. levels of activity the activity levels of the mites at different tem peratures are presented in fig. 2. their activity was very low at o'c, while a maximum level was reached at 10°c. at temperatures above 15°c the activity was greatly reduced. this pattern is in correspondence with the actual temperatures of their microhabitats (fig. 1). water balance the relative water content and the water loss rate were determined in eight specimens of m . wilsoni (table 1). at 15°c and 10% relative humidity a water loss rate of 0.44% h-' was observed. the mites had a low water content of only 43.6%. cold hardiness the supercooling points of 30 adult mites had a mean (-+sd) of -30.8k4.7"c (table 2). for summer acclimated arthropods this is a very low level. as shown in table 2 the haemolymph osmo lality of five adult mites had a mean value of 694 mosmol, corresponding to a melting point of 1.3"c. determination of the hysteresis freezing point was possible only in two specimens, which showed values as low as -4.7 and -6.1'c. discussion the nunataks of the antarctic continent offer some of the most hostile environments on earth. winter conditions prevail for almost ten months and winter temperatures in the range of -40 to -50°c may be expected. studies on the col lembolan cryptopygus sverdrupi from dronning maud land (s@mme 1986b) showed that the tem peratures of their microhabitats may drop below -10°c when they are in the shade. thus, tem peratures may be too low for growth and devel opment during part of the day even in mid summer. similar observations were made during the present study, and the low supercooling points of summer-acclimated m . wilsoni are important for survival under such conditions. thermal hysteresis agents are usually found in insects hibernating in sites where they become exposed to severe cold. the agents are assumed to protect the insects against spontaneous ice nucleation and against inoculation of external ice through the body wall (zachariassen & husby 1982). the presence of thermal hysteresis factors in the body fluids of the mites is likely to reflect the cold temperatures that prevail in the antarctic continent even during the summer. it also sug table 1. initial fresh weight of eight adult specimens of m. wilsoni, weight after 40 hours and mean rate of water loss at 10°c and 10% r.h. dry weight after drying at 80°c and relative water content are also presented. fresh weight (pg) weigh after rate of water loss dry weight water content (f 2 s d ) % (2 2 s d ) f + s d 40 h at 15°c (pdh) 21.2 f 2.2 22.4 2 3.1 0.12 15.2 ? 1.3 43.6 2 5.7 table 2. supercooling points, haemolymph osmolality and thermal hysteresis freezing points of adult m. wilsoni. scp ("c) osmolality (mosmol) hyst. freez. pt. ("c) n f 2 s d n f + s d n range 30 -30.8 f 4.7 5 694? 125 2 -4.71-6.1 24 l . slmme, a. strlmme & k . e . zachariassen gests that the microhabitat of the mites is frozen so that inoculative freezing would occur if not prevented by the thermal hysteresis freezing point. the relatively low osmolality values indicate that the body fluids of the mites do not contain high levels of polyols. this is in agreement with the idea that accumulation of polyols is incom patible with the metabolic requirements of the active state. even winter-active insects, which are active in a supercooled state at temperatures only slightly above the supercooling point, d o not dis play accumulated polyols (husby & zachariassen 1979). since the mites of the present investigation are likely to have been feeding and reproducing at the time when the measurements were made, they probably possess an active metabolic system incompatible with high polyol accumulation. the physiological function of polyols in freeze sensitive insects is to increase the supercooling capacity, so that the insects can experience lower temperatures without undergoing lethal freezing (e.g. s0mme 1982; zachariassen 1985). insects without polyols will usually supercool to only about -20°c. in spite of the absence of accumu lated polyols, the mites of the present study are able to supercool to about -30°c. the relatively low supercooling points of the mites are probably due to their small body size, which will depress the supercooling points by a volume effect (bigg 1953). according to bigg (1953), there is a log arithmic relation between the sample volume of water and the scp, and reduction of water volume by one logarithmic unit is associated with a super cooling point depression of about 2.5"c. while insects which supercool to -20°c have an average body mass of about 150mg, the mites of the present study have a body mass of about 28 pg, i.e. the body masses deviate by a factor of about 5,500, corresponding to 3.74 logarithmic units. according to the data of bigg (1953) this deviation would imply a volume-induced difference in supercooling points of more than 1o"c, which corresponds well to the difference between the supercooling points of the relatively large insects and the relatively small mites. active alpine insects which are exposed to mod erately low temperatures at night are often tol erant to freezing. however, since these insects usually lack accumulated polyols, they tolerate freezing to only about -7°c (van der laak 1982; sbmme & zachariassen 1981). active insects which are exposed t o substantially lower tem peratures must rely on other cold hardening mechanisms than polyol accumulation. freeze avoidance by means of a reduction in body size might be considered as an alternative cold hard ening strategy. at robertskollen, ryan & watkins (1989) found that m. wilsoni is concentrated on the underside of stones, but appears to prefer areas with large amounts of fruticose lichens. since the robertskollen group of nunataks is situated at an elevation of only 200-500 m, they probably have a richer vegetation than the slopes at jutulsessen. both in their study and in the present investigation the mites appeared to feed on microorganisms. further studies on the nutrition of the mites should be carried out to understand the ecology of this species, in particular since a diet free of nucleating agents may be essential for maintaining the species' high supercooling capacity during the summer. acknowledgements. the present study was carried out with the support of the norwegian antarctic research expedition (nare) 1989/90. we would like to thank 0. skulberg for identification of mierophytes from jutulsessen. references aunaas, t . . baust, j . g . & zachariassen, k . e. 1983: eco physiological studies on arthropods from spitsbergen. polar res. 1 n . s . , 235-240. bigg, k . e. 1953: the supercooling of water. proc. phys. soc. lond. 8 6 6 , 6 8 8 4 9 4 . block, w. 1984: terrestrial microbiology, invertebrates and ecosystems. pp. 162-236 in laws, r. m . (ed.): antarctic ecology, vol. i . academic press, london. engelskj~in, t. 1986: botany of two antarctic mountain ranges: gjelsvikfjella and miihlig-hofmannfjella, dronning maud land. i. general ecology and development of the antarctic cold desert cryptogam formation. polar res. 4 n.s., 205-224. husby, j. a . & zachariassen, k. e. 1979: antifreeze agents in the body fluid of winter active insects and spiders. experientia 3 6 , 9 6 3 4 6 4 . norsk polarinstitutt 1990: establishment of troll, a new station facility for summer operations. norsk polarinst. rapp. 65. 26 pp. ryan, p. g . & watkins, b. p. 1989: the influence of physical factors and ornithogenic products on plant and arthropod abundance at an inland nunatak group in antarctica. polar biol. 10, 151-160. mmme, l. 1982: supercooling and winter survival in terrestrial arthropods. comp. biochem. physiol. 73a, 519-543. sgimme, l. 1986a: new records of terrestrial arthropods from dronning maud land, antarctica. polar res. 4 n.s., 225 229. %mme, l. 1986b: ecology of cryptopygus sverdrupi (&i lembola) from dronning maud land, antarctica. polar biol. 6 , 179-184. the ecology and physiology of the antarctic oribatid mite maudheimia wilsoni 25 sbmme, l. & block, w. 1991: adaptations to alpine and polar environments in insects and other terrestrial arthropods. pp. 318-359 in lee, r. e., jr. & denlinger, d. l. (eds.): insects at low temperature. chapman & hall, new york, london. samme, l. & zachariasscn. k. e. 1981: adaptations to low temperature in high altitude insects from mount kenya. ecol. entomol. 6 , 199-204. van der laak, s. 1982: physiological adaptation to low tcm perature in freeze-tolerant phyllodecta laticollis beetles. comp. biochem. physiol. 7 3 a . 613-620. wallwork. j . a . 1967: cryptostigmata (oribatid mites). pp. 105-122 in gressitt, j. l. (ed.): entomology of anrarcrica. antarcfic research series 10. american geophysical union, washington. winther. j . g. 1990: glaciological and meteorological measure ments in dronning maud land. norsk polarinst. medd. 113, zachariassen, k. e. 1985: physiology of cold tolerance in insects. physiol. rev. 65, 799-832. zachariassen, k. e. & husby. j. a . 1982: stabilization of highly supercooled insects by thermal hysteresis antifreeze agents. cryo-letters 3, 316. 81-86. personal submersibles offer novel ecological research access to antarctic waters: an example, with observations of the rarely encountered scyphozoan stygiomedusa gigantea research note personal submersibles offer novel ecological research access to antarctic waters: an example, with observations of the rarely encountered scyphozoan stygiomedusa gigantea daniel m. moore, anne elina flink, eva prendergast & antony gilbert viking expeditions, hamilton, bermuda abstract underwater biological surveys have been conducted around the antarctic continent for several decades, and our knowledge of the species present in the shallow waters (<50 m) is reasonably comprehensive. however, the waters below 50 m remain underexplored on the account of difficulty of access, financial barriers and relatively few operational platforms capable of deployment to such depths. here, we demonstrate that personal submersibles, now increasingly deployed by the expedition cruise industry, can be vessels of opportunity for biological research in the polar regions. we describe direct observations of the rarely encountered scyphozoan stygiomedusa gigantea at water depths of 80–280 m in antarctic peninsula coastal waters as an example of the potential that personal submersibles present for the scientific community, and we outline possible research avenues for utilizing these platforms in the future. keywords submarine; polar; medusa; citizen science; jellyfish; tourism abbreviation ps: personal submersible   citation: polar research 2023, 42, 8873, http://dx.doi.org/10.33265/polar.v42.8873 copyright: polar research 2023. © 2023 d.m. moore et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 30 january 2023 competing interests and funding: all authors are employed by viking expeditions, a subsidiary of viking. all work was funded by viking. correspondence: daniel m. moore, viking expeditions, clarendon house, 2 church street, hm11 hamilton, bermuda. e-mail: daniel.moore@viking.com   introduction the ecology of the mesopelagic and lower epipelagic zones around antarctica is relatively understudied, in part because of the logistical and financial implications of operating at such depths. this can also be considered true for the antarctic benthic environment below scientific scuba survey depths, typically around 50 m. the increasing deployment of recreational manned submersibles from expedition cruise vessels in the waters around the antarctic peninsula provides a novel opportunity to expand our understanding of the marine ecology of this understudied environment. submersibles have long been utilized for biological surveys in depths beyond that accessible by scuba (fricke & meischner 1985; lorance et al. 2000; lindsay & hunt 2005; baker et al. 2021). typically, these submersibles have been owned by nation states and operated by national or academic research institutions (e.g., grassle et al. 1975; hissmann & schauer 2017). however, from the late 1990s and early 2000s, several manufacturers (including u-boat worx, personal submersibles organisation, triton and others) began producing pss. these pss have now been deployed extensively throughout the world ocean for recreational (fairley 2018) and military use, and for commercial purposes by the oil and gas industry (love & york 2005; meyer-gutbrod et al. 2019). ps deployment for scientific use is increasingly common (schrope 2013; phillips et al. 2018), although in the polar regions, the majority of deployments have been for film production (amsler margaret et al. 2017) or, since 2019, for purely recreational use. the increasing deployment of pss in the polar regions by the expedition cruise industry represents a novel platform for research when these vehicles are considered as vessels of opportunity. especially when combined with the advanced research facilities found aboard several new expedition cruise ships, these vessels of opportunity are potentially powerful assets for the scientific community. the large scyphozoan stygiomedusa gigantea (browne, 1910; cnidaria: scyphozoa: semaeostomeae) is a primarily deep-water (1000–3000 m) species, though observed at shallower depths (0–1000 m) in the southern ocean. it has been recorded in all ocean basins except the arctic. stygiomedusa gigantea is currently the only known species within the genus stygiomedusa (matsumoto et al. 2003) since s. stauchi repelin, 1967 and s. fabulosa russell, 1959 are now considered synonyms of s. gigantea. the body form of s. gigantea consists of a smooth and rounded bell, curtained with a pleated skirt and four oral arms. typically, this species appears a deep brown–red hue with a yellow shading to the underside of the bell. stygiomedusa gigantea individuals can reach substantial sizes, with oral arm lengths of over 6 m and bell diameters of 1 m being not unusual for fully mature specimens (benfield & graham 2010). stygiomedusa gigantea is believed to be viviparous (russell & rees 1960). despite their size, records of s. gigantea remain few, with only 126 recorded encounters (including individuals brought up in nets) since the species was described in 1910 (benfield & graham 2010; tarling et al. 2012; schiariti et al. 2018; fig. 1a). the bathymetric distribution of recorded encounters suggests an increased tendency towards shallower depths when in high southern latitudes (fig. 1c). as a result of the limited number of records, very little is known regarding this species’ full distribution, behaviour, environmental preferences, diet or reproductive cycle. it is therefore important for the scientific community to seize any new opportunity to directly observe s. gigantea in its natural habitat. fig. 1 (a) global distribution of documented records of stygiomedusa gigantea with observations from this study highlighted in red. (b) the northern part of the antarctic peninsula, showing the three locations of the observations reported in this note. (c) bathymetric distribution of records by latitude. where exact depth is unknown because the record came from a trawl, the median trawl depth is shown. data taken from benfield & graham (2010). here, we present data from direct observations of s. gigantea conducted from pss deployed from the expedition cruise vessel viking octantis during the 2021/22 antarctic summer season. furthermore, we outline the opportunities for utilizing ps as vessels of opportunity for scientific research. observations twenty-five ps dives were undertaken in a u-boat worx cruise sub-7 mkii 300 from the expedition cruise vessel viking octantis off the antarctic peninsula over the period january–march 2022. dives lasted a maximum of 84 minutes and reached a maximum depth of 300 m. these dives included both training dives and commercial dives with fee-paying guests aboard. during these dives, observations of the large scyphozoan stygiomedusa gigantea were recorded via mobile telephone cameras and professional cameras. during each observation, the ps was hovered, and all lights remained on. direct observations of stygiomedusa gigantea were made from pss deployed from viking octantis three times (see table 1 and fig. 1b). occurrences of s. gigantea were recorded at water depths of 80 m, 87 m and 280 m. on no occasion was more than a single s. gigantea individual observed during a dive. still images of each individual were recorded (fig. 2), along with additional video footage (supplementary material). the three observations were established as different individuals from distinguishing marks on the bell. no quantitative measurements could be made, but each individual observed was estimated to be longer than the length of the ps (4.85 m), and at least double this length for one of the observations. no other species were found in association with s. gigantea individuals. one individual (fig. 2d) bores a distinct knot in one of its oral arms. previous observations of s. gigantea made from a ps deployed by the passenger ship the scenic eclipse have also been reported from antarctic peninsula waters (fig. 1), although the metadata, including exact location and depth, has been lost (gilbert, pers. comm. 2022). table 1 dives undertaken with pss, deployed from viking octantis, from which stygiomedusa gigantea was observed during the 2021/22 antarctic season. date location latitude longitude depth (m) 20/01/22 georges point, rongé island 64°39’9”s 62°38’7”w 80 26/01/22 fournier bay, anvers island 64°31’4’’s 63°8’4’’w 280 15/03/22 brown station, paradise harbour 64°53’9’’s 62°52’5’’w 87 fig. 2 still images of stygiomedusa gigantea individuals encountered in the waters off the antarctic peninsula at (a) georges point, rongé island, at 87 m, (b) fournier bay, anvers island, at 280 m and (c) and (d) paradise harbour, near the argentine antarctic base brown station at 87 m. the individual shown in (c) had a knot in its feeding appendage, shown in more detail in (d). (photos: [a] antony gilbert, [b] mark niesink and [c] and [d] gregory gibbons.) discussion the information in this note highlights the scientific potential of pss as vessels of opportunity in underwater ecological research. that depths of 50 to 300 m are now being accessed with relative frequency in the polar regions provides novel research opportunity for the scientific community. the multiple observations made of the rarely seen stygiomedusa gigantea from just a limited number of ps dives provide a clear example of the scientific utility of pss. previous to this publication, there were only 126 documented records (benfield & graham 2010; tarling et al. 2012; schiariti et al. 2018) of s. gigantea. of these records, 69% were from the high latitude waters of the southern ocean and antarctica (benfield & graham 2010). previous authors have suggested that the larger proportion of sightings in the southern ocean may be due to increased zooplankton sampling effort there. however, the observations presented here add to the emerging impression that the colder waters of the southern high latitudes may be a key habitat for s. gigantea. all of our observations were made at relatively shallow depths (≤280 m). this is in keeping with an apparent tendency towards shallower depths observed in other recorded encounters made at similar southern latitudes. a symbiotic relationship has been reported between the ophidiiform fish thalassobathia pelagica and s. gigantea (harbison et al. 1973; drazen & robison 2004), and it is likely that s. gigantea benefits from the presence of t. pelagica in warmer waters through the removal of parasites (purcell & arai 2001). however, t. pelagica is not found in the southern ocean, and there are no observations of s. gigantea forming associations with alternative fish species found in the southern ocean. we did not observe any other species in association with s. gigantea. it is possible that the lower prevalence and slower growth of parasites in colder waters (harvell et al. 2002) may mitigate the need for such a symbiosis when s. gigantea is located in southern high latitudes. conclusion underwater scientific surveys in antarctica have been conducted via scuba since the 1950s (pollock 2007), with recreational scuba operations becoming significant in the early 2000s (lamers & gelter 2012). this has led to a fairly good understanding of species found down to 50 m. below 50 m, the antarctic marine environment remains under-explored. the increasing deployment of pss from antarctic expedition cruise vessels presents a novel opportunity for the scientific community to access these under-explored waters. additionally, most antarctic tour operators that deploy pss also operate remotely operated vehicles for safety reasons, and this presents further opportunities for scientific data collection, as has been demonstrated in other regions of the world (macreadie et al. 2018; mclean et al. 2020). pss have the potential to be enhanced for scientific data collection relatively easily by the addition of conductivity–temperature–density sensors (jonsson et al. 2013), advanced camera arrays (phillips et al. 2016) and parallel laser systems (laidig et al. 2013). ps deployment could also be scientifically optimized by dive plans that include same-depth or vertical transects. citizen science projects onboard expedition cruise vessels, such as those coordinated by the polar collective, are popular with guests and have contributed to numerous scientific publications (e.g., taylor et al. 2019). there is great potential to harness data from citizen scientists following ps deployment, whereby any georeferenced imagery data are gathered across operators and collectively analysed to build our understanding of polar underwater biotopes and species. consideration should be given in advance to additional data-gathering equipment required onboard pss and the storage of data post-dive, including that gathered by citizen scientists. acknowledgements the authors would like to thank all guests and crew of the viking octantis, without whom this work would not have been possible. in particular, we thank submarine pilots mark andrews, remy izendooren and sven sudar. we are also grateful to prof. julian dowdeswell and emily cunningham for comments that helped to improve this manuscript. finally, we wish to thank dr damon stanwell-smith for his scientific oversight at viking expeditions, which laid the foundations for this work. references amsler margaret o., de broyer c. & bolstad k. 2017. in situ submersible observations of western antarctic peninsula deep sea fauna. in a. van de putte (ed.): book of abstracts. xiith scar biology symposium. leuven, belgium, 10–14 july. p. 37. cambridge: scientific committee on antarctic research. baker m.r., williams k., greene h.g., greufe c., lopes h., aschoff j. & towler r. 2021. use of manned submersible and autonomous stereo-camera array to assess forage fish and associated subtidal habitat. fisheries research 243, article no. 106067, doi: 10.1016/j.fishres.2021.106067. benfield m.c. & graham w.m. 2010. in situ observations of stygiomedusa gigantea in the gulf of mexico with a review of its global distribution and habitat. journal of the marine biological association of the united kingdom 90, 1079–1093, doi: 10.1017/s0025315410000536. drazen j.c. & robison b.h. 2004. direct observations of the association between a deep-sea fish and a giant scyphomedusa. marine and freshwater behaviour and physiology 37, 209–214, doi: 10.1080/10236240400006190. fairley p. 2018. triton submarines’ dive into luxury: these manoeuvrable subs are prized by scientists and yachters alike. ieee spectrum 55(10), 17–18, doi: 10.1109/mspec.2018.8482415. fricke h. & meischner d. 1985. depth limits of bermudan scleractinian corals: a submersible survey. marine biology 88, 175–187, doi: 10.1007/bf00397165. grassle j.f., sanders h.l., hessler r.r., rowe g.t. & mclellan t. 1975. pattern and zonation: a study of the bathyal megafauna using the research submersible alvin. deep sea research and oceanographic abstracts 22, 457–481, doi: 10.1016/0011-7471(75)90020-0. harbison g.r., smith k.l. & backus r.h. 1973. stygiomedusa fabulosa from the north atlantic: its taxonomy, with a note on its natural history. journal of the marine biological association of the united kingdom 53, 615–617, doi: 10.1017/s0025315400058811. harvell c.d., mitchell c.e., ward j.r., altizer s., dobson a.p., ostfeld r.s. & samuel m.d. 2002. climate warming and disease risks for terrestrial and marine biota. science 296, 2158–2162, doi: 10.1126/science.1063699. hissmann k. & schauer j. 2017. manned submersible “jago”. journal of large-scale research facilities 3, article no. a110, doi: 10.17815/jlsrf-3-157. jonsson j., smedfors k., nyholm l. & thornell g. 2013. towards chip-based salinity measurements for small submersibles and biologgers. international journal of oceanography 2013, article no. 529674, doi: 10.1155/2013/529674. laidig t.e., krigsman l.m. & yoklavich m.m. 2013. reactions of fishes to two underwater survey tools, a manned submersible and a remotely operated vehicle. fishery bulletin 111, 54–68, doi: 10.7755/fb.111.1.5. lamers m. & gelter h. 2012. diversification of antarctic tourism: the case of a scuba diving expedition. polar record 48, 280–290, doi: 10.1017/s0032247411000246. lindsay d.j. & hunt j.c. 2005. biodiversity in midwater cnidarians and ctenophores: submersible-based results from deep-water bays in the japan sea and north-western pacific. journal of the marine biological association of the united kingdom 85, 503–517, doi: 10.1017/s0025315405011434. lorance p., latrouite d. & séret b. 2000. observations of chondrichthyan fishes (sharks, rays and chimaeras) in the bay of biscay (north-eastern atlantic) from submersibles. in b. séret & j.-y. sire (eds.): procedeedings of the 3rd european elasmobranch association meeting, boulogne-sur-mer, 1999. pp. 29–45. paris: french ichthyological society. love m.s. & york a. 2005. a comparison of the fish assemblages associated with an oil/gas pipeline and adjacent seafloor in the santa barbara channel, southern california bight. bulletin of marine science 77, 101–118. macreadie p.i., mclean d.l., thomson p.g., partridge j.c., jones d.o.b., gates a.r., benfield m.c., collin s.p., booth d.j., smith l.l., techera e., skropeta d., horton t., pattiaratchi c., bond t. & fowler a.m. 2018. eyes in the sea: unlocking the mysteries of the ocean using industrial, remotely operated vehicles (rovs). science of the total environment 634, 1077–1091, doi: 10.1016/j.scitotenv.2018.04.049. matsumoto g.i., raskoff k.a. & lindsay d.j. 2003. tiburonia granrojo n. sp., a mesopelagic from the pacific ocean representing the type of a new subfamily (class scyphozoa: order semaeostomeae: subfamily tiburoniinae subfam. nov.). marine biology 143, 73–77, doi: 10.1007/s00227-003-1047-2. mclean d.l., parson m.j.g., gates, a.r., benfield m.c., bond t., booth d.j., bunce m., fowler a.m., harvey e.s., macreadie p.i., pattiaratchi c.b., rouse s., partridge j.c., thomson p.g., todd v.l.g. & jones d.o.b. 2020. enhancing the scientific value of industry remotely operated vehicles (rovs) in our oceans. frontiers in marine science 7, article no. 220, doi: 10.3389/fmars.2020.00220. meyer-gutbrod e.l., love m.s., claisse j.t., page h.m., schroeder d.m. & miller r.j. 2019. decommissioning impacts on biotic assemblages associated with shell mounds beneath southern california offshore oil and gas platforms. bulletin of marine science 95, 683–702, doi: 10.5343/bms.2018.0077. phillips b.t., becker k.p., kurumaya s., galloway k.c., whittredge g., vogt d.m., teeple c.b., rosen m.h., pieribone v.a., gruber d.f. & wood r.j. 2018. a dexterous, glove-based teleoperable low-power soft robotic arm for delicate deep-sea biological exploration. scientific reports 8, article no. 14779, doi: 10.1038/s41598-018-33138-y. phillips b.t., gruber d.f., vasan g., roman c.n., pieribone v.a. & sparks j.s. 2016. observations of in situ deep-sea marine bioluminescence with a high-speed, high-resolution scmos camera. deep-sea research part i 111, 102–109, doi: 10.1016/j.dsr.2016.02.012. pollock n.w. 2007. scientific diving in antarctica: history and current practice. diving and hyperbaric medicine 37, 204–211. purcell j.e. & arai m.n. 2001. interactions of pelagic cnidarians and ctenophores with fish: a review. hydrobiologia 451, 27–44, doi: 10.1023/a:1011883905394. russell f.s. & rees w.j. 1960. the viviparous scyphomedusa stygiomedusa fabulosa russell. journal of the marine biological association of the united kingdom 39, 303–318, doi: 10.1017/s0025315400013345. schiariti a., dutto m.s., pereyra d.y., siquier g.f. & morandini a.c. 2018. medusae (scyphozoa and cubozoa) from southwestern atlantic and subantarctic region (32–60 s, 34–70 w): species composition, spatial distribution and life history traits. latin american journal of aquatic research 46, 240–257, doi: 10.3856/vol46-issue2-fulltext-1. schrope m. 2013. giant squid filmed in its natural environment. nature, doi: 10.1038/nature.2013.12202. tarling g.a., stowasser g., ward p., poulton a.j., zhou m., venables h.j., mcgill r.a.r. & murphy e.j. 2012. seasonal trophic structure of the scotia sea pelagic ecosystem considered through biomass spectra and stable isotope analysis. deep-sea research part ii 59, 222–236, doi: 10.1016/j.dsr2.2011.07.002. taylor a.r., barðadóttir þ., auffret s., bombosch a., cusick a.l., falk e. & lynnes a. 2019. arctic expedition cruise tourism and citizen science: a vision for the future of polar tourism. journal of tourism futures 6, 102–111, doi: 10.1108/jtf-06-2019-0051. a review of the ecology and status of white whales (delphinapterus leucas) in svalbard, norway review article a review of the ecology and status of white whales (delphinapterus leucas) in svalbard, norway christian lydersen & kit m. kovacs norwegian polar institute, fram centre, tromsø, norway abstract the norwegian polar institute initiated a research programme on white whales in 1995 to gather biological information relevant for the species’ management; the results of which are reviewed herein. satellite tracking from two periods (1995–2001 and 2013–16), between which sea ice diminished markedly, showed that the whales in waters off the archipelago of svalbard spent most of their time foraging close to tidewater glaciers. transits between glaciers typically followed the coastline, with the whales moving rapidly from one glacier to another. during the later period, the whales spent some time out in the fjords, suggesting that they might be targeting prey in the atlantic water masses that now prevail in svalbard’s west-coast fjords. most of their dives were extremely shallow (13 ± 26 m; maximum 350 m) and of short duration (97 ± 123 s; maximum 31.4 min). fatty-acid analyses indicated that polar cod (boreogadus saida) was the main prey during the first sampling period. an aerial survey in 2018 estimated the population numbered 549 (ci: 436–723) animals. svalbard white whales are genetically separate from populations off west greenland and in the white sea. predation by killer whales appears to have influenced white whale behaviour in svalbard; they are often silent, despite having a normal vocal repertoire for the species and their coastal movements take place in very shallow water. this population has extremely high contaminant levels. climate change poses a threat to this small population of white whales. keywords abundance; beluga; climate change; genetics; tracking; pollution abbreviations ci: confidence interval ctd: conductivity–temperature–depth max: maximum min: minimum pop: persistent organic pollutant   citation: polar research 2021, 40, 5509, http://dx.doi.org/10.33265/polar.v40.5509 copyright: polar research 2021. © 2021 c. lydersen & k.m. kovacs. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 12 november 2021 competing interests and funding: the authors report no conflict of interest. this study was supported financially by the norwegian polar institute, the norwegian research council (through the projects ice whales [244488/e10], tidewater glacier retreat impact on fjord circulation and ecosystems and glaciers as arctic ecosystem refugia), the norwegian polar institute’s centre for ice, climate and ecosystems and the fram centre’s fjord and coast flagship programme. this review was presented at the second international workshop on beluga whale research and conservation, 12–14 march 2019, mystic aquarium, mystic, ct, usa. this special issue on white whales in polar research was funded by the ministry of climate and environment (norway) on behalf of conservation of arctic flora and fauna (caff). correspondence to: christian lydersen, norwegian polar institute, po box 6606 langnes, no-9296 tromsø, norway. e-mail: christian.lydersen@npolar.no this article is part of the special cluster beluga whales (delphinapterus leucas): knowledge from the wild, human care and tek, which has been funded by mystic aquarium, caff and the norwegian ministry of climate and environment. introduction the svalbard archipelago was discovered by willem barentsz in 1596, and the first commercial whaling enterprise commenced the year following. initially, harvests were focused on bowhead whales (balaena mysticetus). when their numbers declined, marine mammal harvests diversified in the archipelago, with polar bears (ursus maritimus), walruses (odobenus rosmarus) and seals being targeted. russian whalers began harvesting white whales (delphinapterus leucas) in the area early in the 17th century, mainly operating in the fjords on the west coast of spitsbergen. documentation of these early catches is sparse. however, one crew wintering at the southernmost tip of spitsbergen reported taking about 1200 whales in 1818 (isachsen 1921). norwegians joined in the fishery for white whales in svalbard in 1866 and continued harvesting until whaling ended in the early 1960s, when the species became protected in svalbard. at this time, the population was described as being severely depleted and ‘commercially extinct’ (gjertz & wiig 1994). in total, about 15 000 whales were landed in documented catches (lønø & øynes 1961; gjertz & wiig 1994). despite the fact that white whales are resident in svalbard and were hunted for an extended period, very little was known about the ecology and biology of these whales in norwegian waters until quite recently. the norwegian polar institute initiated the first field-based research programme on white whales in 1995, with the objective of gathering biological information relevant to the management of this species in svalbard. because white whales are protected in the archipelago, research was restricted to observational studies, minimally invasive instrumentation, and collection of tissues from live animals. the first white whales were live-captured for scientific purposes in 1995, and since then, white whales have been part of the norwegian polar institute’s biodiversity programme, with field campaigns occurring at irregular intervals. most expeditions have been undertaken using a sailboat ‘camp’ with two towed zodiacs for search and capture activities. a few larger-scale expeditions (survey work or late-season capture activities) have been undertaken with ship support. when animals were encountered, the five–six-person research team used shore-anchored nets to live-capture whales. a total of 76 white whales have been caught, and tissue samples have been collected for various studies from all these animals; 38 of these whales have been instrumented with biologging devices. results from these studies of the ecology and status of white whales in the svalbard archipelago are summarized herein. tracking studies white whales in svalbard have been instrumented with various types of satellite relayed data loggers (fig. 1) produced by the sea mammal research unit, university of st andrews, during two research programme periods (1995–2001 and 2013–16). thirty-eight individuals have been instrumented, resulting in a total of 2055 tracking days (fig. 2). the first published work from these efforts was based on 15 adult whales (14 males and one female) instrumented during the summer seasons from 1995 to 1999 (lydersen et al. 2001). the whales spent most of their time (55.6%) close to tidewater glacier fronts. such areas are known to have high abundances of fish and invertebrates (lydersen et al. 2014), so it was assumed that these areas were key foraging sites. the whales moved from one glacier front to another in a rapid and directed manner, staying very close to shore in shallow waters. although killer whales (orcinus orca) are not particularly common in svalbard currently (storrie et al. 2018), the behaviour of svalbard white whales during transits between glacier fronts is similar to responses to the presence of this predator in other arctic areas (finley et al. 1990). fig. 1  sea mammal research unit’s (university of st andrews, scotland) satellite-relayed data loggers fitted to the dorsal ridge of adult male white whales in svalbard. through the argos satellite system, the loggers relay data on position, dive depth and duration and measure temperature in the water column the whales dive through. fig. 2  map showing all positions received from tracking studies of white whales in svalbard. location points are from 1897 tracking days for 34 males (blue dots) and 158 tracking days for four females (red dots). the second tracking study of white whales in svalbard, conducted in 2001, included testing of a prototype for a satellite-linked ctd logger (lydersen et al. 2002). white whales were chosen as the subject for this work because they are small enough to be captured and handled, yet big enough to carry the first-generation of ctd loggers without undue stress. fieldwork was conducted late in the year (november), in hopes that the tags would still function when sea ice formed and the whales moved offshore into deeper waters. the prototype tags worked and the 540 ctd profiles that were successfully transmitted revealed new information about the hydrographic conditions in the study area during early winter (fig. 3), including the presence of a bathymetrically steered warm-water mass that circulated within storfjorden. perhaps more importantly, this study demonstrated the feasible of using marine mammals to collect oceanographic data in a cost-effective manner to study the habitat of the animals in situ, as well as providing data for physical oceanography studies. the use of advanced generations of these tags has been revolutionary in terms of data collection, particularly from remote, hard to access, ice-covered areas in polar regions (see, for example, www.meop.net). these tags also documented that white whales occupied areas that had sea-ice concentrations up to 90% and that the whales routinely dove to the bottom to forage under extensive drift ice during late fall and winter. fig. 3  ctd transects in storfjorden, svalbard. the maps show the locations of selected dives performed by a white whale (each yellow spike represents a dive; the length of the spikes represents dive depth) carrying a ctd tag, along (a) a north–south transect and (c) an east–west transect superimposed on a three-dimensional bathymetric map of storfjorden, svalbard. ctd casts produced during these dives are the basis for the temperature and salinity profiles shown in (b) and (d), respectively. each dot in (b) and (d) represents a location where a ctd measurement was taken. (figure from lydersen et al. 2002.) the third tracking study was conducted in 2013–16, with the primary purpose of investigating whether the distribution or behaviour of white whales had been altered by the rapid changes in environmental conditions that took place in the early 2000s as a result of global warming (vacquie-garcia et al. 2018). environmental conditions, especially on the west coast of svalbard, changed precipitously in 2006, when large influxes of warm atlantic water prevented shore-fast sea ice from forming. although sea ice does cover some small sill fjords and, in some years, open fjord areas, the sea-ice extent and thickness has not returned to pre-2006 levels. in addition to the declines in the available sea ice, the glacier fronts that the whales used for foraging are shrinking as higher air and water temperatures are causing negative mass balance, inducing melt and retraction of tidewater glaciers up onto shore (see lydersen et al. 2014 for details). the tracking study showed that glacier fronts were still important areas for white whales in svalbard, but that they spent significantly less time in this habitat than previously (vacquie-garcia et al. 2018). during the recent tracking period, the whales spent more time out in the fjords, sometimes kilometres away from the coastline. this was especially pronounced on the west side of svalbard and suggests that the whales have likely diversified their foraging patterns to include prey in the atlantic water masses that now prevail in these fjords (hamilton et al. 2019). it appears that the white whales are coping with current changes in the environment by displaying some behavioural plasticity, unlike another arctic marine mammal in this area, the ringed seal (pusa hispida), which has retracted into small home ranges very close to glacier fronts and has not shifted to the new potential prey available in the atlantic water (hamilton et al. 2019; bengtsson et al. 2020). this tracking study also showed that there was a seasonal pattern (both in the new and old data set) to the whales’ distribution: the white whales spent the majority of their time in summer on the west coast of svalbard and moved to the east coast during winter, occupying drift-ice areas, sometimes with ice concentrations of 80–100% (vacquie-garcia et al. 2018). the tracking data from these white whales have also been used for methodological studies. used in combination with tracking data from several other species, a new algorithm based on swimming speed, distance between successive argos locations and turning angles was developed to filter tracks. this new speed–distance–angle filter preserved a significantly higher percentage of good-quality argos positions compared to other filters that used only estimated speed of travel to cull potentially erroneous location points (freitas, lydersen et al. 2008). another study presented a novel method for quantifying habitat selection and predicting habitat use for white whales, as well as and ringed seals (freitas, kovacs et al. 2008). habitat use intensities are explored using first-passage time, and these data were then used in cox proportional hazard models to quantify habitat selection. this new combination of analyses permitted evaluation of which habitat characteristics best explained the risk (or ‘hazard’) of the animal leaving an area of a given radius (i.e., what features of the habitat were preferred). in addition, these models can be used to construct spatial predictions, such as maps of population-level space use that can be useful in the design of protected areas (freitas, kovacs et al. 2008). diving analyses of 55 000 dives collected from the tracking records of adult males (2013–16) showed that svalbard white whales rarely dive to great depth, which is not surprising given their close association with the coast (vacquie-garcia et al. 2019). average dive depth was only 13 ± 26 m (max recorded depth = 350 m), and dive durations were very short (average 97 ± 123 s, max 31.4 min; vacquie-garcia et al. 2019). no diel patterns were found; however, dive behaviour did vary with the habitat the whales occupied. when the animals were in front of glaciers, they optimized the time spent at the bottom of their dives, and dives were followed by longer periods of resting at the surface, in accordance with what would be expected when foraging. this type of dive behaviour was also documented during some of the time that the animals spent out in the fjords away from the coastline, providing further support that the white whales in svalbard probably do some of their foraging within the fjords in recent years. similar to the earlier tagging period, transits between fjords followed the coastline, and dives during transits were shallow, with the whales swimming just below the surface much of the time. finally, when sea ice forms along the coast in the autumn/winter, the whales are forced to leave the shore and move into areas with deeper waters and drifting ice. in this habitat, they dive deeper, down to the seabed, and they minimize their time at the surface. the limited surface time might be in part to avoid surface predation by polar bears in dense sea-ice areas (vacquie-garcia et al. 2019). the dive data have also been used to calculate surface-availability correction factors for white whale aerial surveys (vacquie-garcia et al. 2020). diet since there is no harvest of white whales in svalbard, indirect approaches have been used to study their diet. the fatty-acid composition of the blubber from live-captured adult male white whales off the west coast of svalbard was analysed and compared by dahl et al. (2000), with the fatty acid composition of various potential prey species. complete-column blubber biopsies from the whales and whole-body compositions of 12 potential prey species were homogenized (separately), and their fatty acids were extracted and analysed. the blubber of the whales consisted almost entirely of triacylglycerols. sixteen of the 22 fatty acids that were consistently found in the blubber of the whales were also found in most of the potential prey species. a principal component analysis run on these 16 fatty acids suggested that the most common prey was polar cod, followed by capelin (mallotus villotus) and some invertebrates, including the shrimp pandalus borealis (dahl et al. 2000). the staple diet of calves is milk, and on several occasions, females with young calves have been captured during the net captures in svalbard. in 1998, three mother–calf pairs were captured, and milk was collected from all three mothers. two of the mothers were grey (young animals), while the third mother was pure white (likely >20 years of age). two of the calves still had their umbilical cords attached; they were 142 and 143 cm long, respectively. the third calf was older and was 205 cm long (with no remaining umbilical cord). all the milk samples had a greenish colour, and chemical analyses of the milk composition showed fat contents of 30.7%, 33.2% and 43.7% and protein contents of 8.10%, 8.69% and 7.26% for the shortest, medium and longest calf, respectively (lydersen & kovacs, unpubl. data). the fat content of the milk seems to increase during the lactation period, similar to what is shown in most seal species (lydersen & kovacs 1999). this is thought to be a means of maintaining water balance (i.e., decrease water content in the milk) in the mother as lactation progresses; the calf is also likely more capable of digesting and mobilizing the fat in the milk as it grows older as well. typical of marine mammals, the white whale milk contained very few carbohydrates (urashima et al. 2002). chemical composition of the oligosaccharides in white whale milk from svalbard showed that the milk had no free lactose, suggesting that this normally common carbohydrate is not an important source of energy for these whales (urashima et al. 2002). another study involving milk analysed the fatty acid composition in the milk, as well as in the blubber of calves and their mothers in parallel (birkeland et al. 2005). four mother–calf pairs were included in this study: the three pairs mentioned earlier in addition to another pair in which the calf was 255 cm long. based on data on body lengths versus age from west greenland (heide-jørgensen & teilmann 1994), two of the calves were estimated to be less than one week old, one was two months old and the largest calf was approximately one year old (birkeland et al. 2005). the youngest calves had fatty-acid compositions that were significantly different from the fatty-acid composition of either the milk or the blubber of their mothers (fig. 4). the fatty-acid composition in the milk was also significantly different from the fatty-acid composition of the adult whales studied previously. the fatty-acid composition of the blubber of the calves changed gradually with age and became more similar to that of their mothers, rather than the fatty acid composition of the milk (i.e., their diet). the oldest calf had a fatty-acid composition similar to that of adult whales (birkeland et al. 2005). these ontogenetic changes during growth occur semi-autonomously of the diet. although all nutrients obviously come from the milk ingested, the relative composition of the fatty acids changed in terms of uptake and deposition into the blubber of the youngsters. anatomical or physiological adjustments crucial to survival in the cold marine environment likely have a strong role in governing how and where various fatty acids are deposited in the early life of calves. this selective processing of fatty acids is likely quite different during ontogeny compared with fat deposition later in life. fig. 4  biplot of the fatty-acid composition in blubber samples from white whale mothers and calves and in milk samples. the calf in the mother–calf pair represented in blue was the youngest, followed by red, green and yellow (the oldest calf). (figure modified from birkeland et al. 2005.) distribution and abundance white whales are commonly observed around the archipelago during the seasonal period with daylight (march–november). they often occur near settlements on the west coast of svalbard, including the ny-ålesund research station in kongsfjorden (hop et al. 2002), in adventfjorden (close to longyearbyen) and near the russian settlement in barentsburg, located in grønfjorden (norwegian polar institute marine mammal sightings database, www.npolar.no\en\services\mms). based on 286 observations of groups comprising 5700 individuals (during the period 2002–2014), white whales were found to occupy a unique, narrow, shallow-water, coastal niche in the cetacean community of the archipelago (storrie et al. 2018). many of the observations reported in storrie et al. (2018) were in areas with considerable ice cover (>30% ice cover), although observations were also recorded in ice-free waters. sea surface temperatures where white whales were observed were colder than where the migrant cetaceans (e.g., fin [balaenoptera physalus], blue [b. musculus], humpback [megaptera novaeangliae] and minke [balaenoptera acutorostrata] whales) were found, with about 25% of the observations occurring in areas with sea-surface temperatures below 2°c (storrie et al. 2018). no white whales were observed in offshore areas during an aerial survey of ice-associated whales, covering a 53 000 km2 area along the marginal ice zone, during summer 2015 (vacquie-garcia et al. 2017). observations reported to the sighting database during the period of the offshore survey included normal sighting levels for white whales along the coast (vacquie-garcia et al. 2017). when summing up the world population size for white whales in the handbook of marine mammals (brody 1989), it is stated that lønø & øynes (1961) found a previous estimate of 10 000–12 000 animals excessive for the svalbard population. this is a slightly erroneous citation of lønø & øynes (1961), who actually refer to a statement from a white whale hunter who suggested that a large white whale group that he came across consisted of 10 000–12 000 animals. lønø & øynes (1961) did indeed question this number, although it has been repeatedly cited in popular literature as though it was the result of an abundance survey. in fact, the population size of white whales in svalbard was simply unknown until the first survey of the population in 2018 (vacquie-garcia et al. 2020). data from the tracking studies described earlier were crucial when creating the survey design, which included three strata to account for the unusual distribution pattern of this population. because of their tightly coastal distribution, the entire coastline of all of the major islands in the archipelago was surveyed. in addition, based on the recent change in the behaviour described earlier, the fjords on the west coast of svalbard were surveyed using a distance sampling line transect design. in addition, in order to account for whales that were potentially not following the documented behavioural patterns, transect lines perpendicular to the coastline were flown from the coastline stratum out into offshore areas. these transects were composed of two parallel lines (one outbound and one inbound) extending out to 12 km, flown 90 km apart throughout the whole of svalbard (fig. 5). in total, 4965 km of coastline, 1481 km of fjord transects and 535 km of offshore transects were flown. groups of white whales were observed on 22 occasions, all within the coastline stratum (vacquie-garcia et al. 2020). after correcting for surface availability based on the diving study described earlier, the svalbard population of white whales was estimated to consist of 549 (ci: 436–723) animals (vacquie-garcia et al. 2020). this makes the svalbard population one of the smallest white whale populations in the world, which is of concern given ongoing climate change and other threats to these animals that could limit the recovery of this population. fig. 5  locations of white whale sightings during an aerial survey of svalbard, norway, summer 2018. asterisks represent mother–calf pair sightings. red lines represent coastlines surveyed, yellow lines the transects flown in the fjords on the west coast of svalbard and green lines show offshore transect lines flown from shore to offshore areas perpendicular to the coastline. (figure from vacquie-garcia et al. 2020.) genetics in a recent global review of narwhals (monodon monoceros) and white whales, 21 extant white whale stock were recognized (hobbs et al. 2019). in this assessment, svalbard is delineated as an independent stock, while another stock to the east—called the barents–kara–laptev seas stock—includes animals in the waters of the russian archipelago of franz josef land. however, there are no genetic studies that compare material from the svalbard stock to animals in franz josef land or the kara or laptev seas, so this stock delineation is somewhat uncertain. animals in the white sea in russia and in west greenland have been investigated in relation to svalbard animals, and all three of these show genetic differences from each other (o’corry-crowe et al. 2010). from the early tracking studies in svalbard, it was apparent that the whales caught and tagged in the southern parts of the archipelago did not move into the northern parts of the archipelago. because white whales are certainly present in the north, this raised the question as to whether there were genetic subgroups among the white whales in this area. therefore, the population structure was studied using various molecular markers to compare allele frequencies and haplotypes between white whales in the north (krossfjorden) and in the south (storfjorden; fløystad 2012). analyses indicated all of the animals in svalbard waters belong to a single population. svalbard white whales have also been included in a comprehensive study of group structure and kinship in white whale societies (o’corry-crowe et al. 2020). white whales are highly social animals that live in groups. the average group size in svalbard is 10, although groups up to 220 have been recorded (storrie et al. 2018; norwegian polar institute marine mammal sighting database). it has been suggested that white whale groups might be families connected through related females (palsbøll et al. 2002), similar to killer whales and sperm whales (physeter macrocephalus). however, mtdna-microsatellite profiling combined with relatedness and network analyses suggested a more complex nature to social groupings of white whales when viewed across their circumpolar range (o’corry-crowe et al. 2020). this species appears to have a much more complex arrangement of extended relationships between family members and other individuals, with seasonal sex segregation being a common feature in svalbard and elsewhere. pod structure is quite dynamic and groups do sometimes, but not always, comprise related individuals. when relatedness is high, it is often through paternal linkages. the long-life span of white whales and the extended community they live in probably facilitate the exchange of knowledge among generations and may allow for the animals to benefit from long-term mutual co-operation. harvesting older animals, particularly in small populations, risks the loss of essential ecological knowledge within the group (o’corry-crowe et al. 2020). genetic studies should be conducted to determine whether the white whales in svalbard and in franz josef land are independent populations or if the animals in these two archipelagos are one common population. the ice edge linking svalbard and franz josef land—and therefore, the likeliest white whale travel route between the two archipelagos—is shortest and most clearly defined during the winter, when it furthest south, but it is not known whether exchange between these populations takes place now or has taken place in the past. currently, contact seems improbable, but heavier ice conditions in the past and larger population size might have facilitated more regular exchange, although natal fidelity might have always kept the whales in these two areas genetically separated (o’corry crowe et al. 2018). acoustics white whales are considered one of the most vociferous cetacean species and are often referred to as the canaries of the sea. however, svalbard’s white whales are remarkably quiet (karlsen et al. 2002). this population does produce most of the vocalizations that have been documented in other populations, as well as some minor vocal novelties, but groups are quiet most of the time (karlsen et al. 2002). this relative silence could be due to the type of groups encountered (e.g., all-male) during the study but is more likely an anti-predator strategy in response to killer whales. lack of vocal signalling, in combination with their extremely tight coastal movement pattern (described earlier), suggests that predation is (or at least has been) an important factor shaping the behaviour of the svalbard white whales. passive acoustic data loggers were used in a remote survey of white whales that included whales in kongsfjorden, a site in alaska and a site in the white sea, russia (castellote et al. 2013). a combination of captive and open-water surveys in these three sites was used to document detection performance and to explore the use of logger angle and inter-click interval data to look at activity patterns and tidal influences on space use. one issue here, which is very relevant for svalbard, is that long periods of silence may result in the loggers underestimating the presence of this species in an area. van parijs et al. (2003) analysed recordings of vocalization during capturing events of white whales in svalbard. only half of the animals (four out of eight) produced sounds during these events. one sub-adult female produced repetitive broadband clicks, while a solitary calf produced harmonic sounds, which were interpreted as being mother–calf ‘contact calls.’ in addition, the mother in a mother–calf pair produced ‘crooning’ broadband clicks while moving her head toward her calf. her calf produced three types of frequency-modulated sounds, interspersed within broadband click trains. even if the sounds produced by these individuals during handing were highly variable, they all likely represented various ‘contact calls.’ no sounds were heard from any of the animals during their period of restraint or upon their release or during other recording sessions when animals were seen passing the capture net (van parijs et al. 2003). environmental pollution all odontocete whales have a poor capacity to metabolize pops, which might play a role in the high concentrations of various pops documented in svalbard and elsewhere in white whales (andersen et al. 2001; wolkers et al. 2004; andersen, foreid et al. 2006; wolkers et al. 2006; villanger et al. 2011; hoguet et al. 2013; villanger et al. 2020). for many compounds, white whales have higher concentrations than polar bears even if the whales feed at lower trophic levels. for instance, ∑ddt is five times higher in white whales in svalbard compared to polar bears in the same area (andersen et al. 2001) and some toxaphenes congeners are more than 200 times higher (andersen, foreid et al. 2006), though these two studies might be biased towards high levels because they were based on only adult males. in a study of accumulation of flame retardants (polybrominated diphenyl ethers) in the food chain in svalbard, 13 different congeners were detected in white whales (of both sexes), while only one was detected in polar bears (wolkers et al. 2004). this is because polar bears have the capacity to metabolize almost all of these flame retardants, which make that species unsuitable as an indicator of these compounds in the environment. white whales, on the other hand, are very suitable for such monitoring. some of the levels of various pops in white whales are a concern because they are found at levels high enough to induce disruptive effects on the whales’ endocrine system, potentially causing negative effects on development, behaviour, fertility and survival. in a study in which levels of 56 organohalogen contaminants were measured together with circulating levels of thyroid hormones and thyroid stimulating hormones in white whales of both sexes (in various age groups) in svalbard, negative influences of specific contaminants on the levels of thyroid hormones in the whales were found, with unknown effects on the health of the individuals or the population (villanger et al. 2011). a study of concentrations of perfluoroalkyl substances in white whales from 1996 to 2001 was compared with levels in white whales collected 15 years later, in 2013–14 (villanger et al. 2020); samples in both periods included a mix of both sexes and a variety of age groups. in contrast to the substances mentioned earlier, which accumulate predominantly in lipid-rich tissues, perfluoroalkyl substances are mainly found in protein-rich tissues. the dominant perfluoroalkyl substance in white whales in svalbard (perfluorooctane sulfonate) declined by 44% from the earlier to the later period, mainly as a result of a production phase-out and eventually global restriction on these compounds. some other substances (perfluoroalkyl carboxylates) increased during the same period, which calls for continued vigilance and regular monitoring, as well as studies of biological effects of these and other contaminants (villanger et al. 2020). halogenated dimethyl bipyrrols are naturally produced organohalogens that are globally distributed in the marine environment. their levels were quantified by tittlemier et al. (2002) in a number of marine mammals, including white whales in svalbard. the geographical distribution of these compounds does not resemble that of anthropogenic organohalogens and suggests that transport (both atmospheric and by ocean currents) of these substances is from a source in the pacific ocean. halogenated dimethyl bipyrrols contribute significantly to an organism’s total organohalogen burden and likely have a long lifetime in the marine environment (tittlemier et al. 2002). andersen, gwynn et al. (2006) studied the specific activity of the anthropogenic radionuclide 137cs in muscle tissue from various marine mammals in svalbard, including white whales. the concentration found was low (0.67 bq/kg w.w.), which is consistent with previously reported results showing low specific activities of this radionuclide in the barents–greenland sea region during the last 20 years. health and diseases serum chemistry was assessed from 21 live-captured white whales in svalbard, including calves, sub-adults and adults of both sexes, by tryland et al. (2006). concentrations of a suite of enzymes, metabolites and minerals were measured from what was assumed to be healthy animals to create a baseline for future health assessments. with some few exceptions, the measured concentrations of the various substances were strikingly similar to values reported from a white whale population in the canadian arctic. another study related to assessing health in svalbard’s white whales measured total serum concentrations of 11 thyroid hormones and associated metabolites using a newly developed liquid chromatography tandem mass spectrometry method (hansen et al. 2017). in addition, thyroid hormone levels in plasma and serum were compared, since many researchers consider serum to be the optimal matrix for such analysis, while plasma is the matrix most often sampled in the field. the analyses showed the same results for both serum and plasma (hansen et al. 2017). in a study of the prevalence of the parasite toxoplasma gondii in svalbard, where plasma from many marine mammal species was analysed, antibodies were found in polar bears, ringed and bearded seals (erignathus barbatus) but not in white whales (jensen et al. 2010). other potential anthropogenic impacts data for svalbard’s white whales were also part of a circumpolar study where the distribution of all arctic endemic cetaceans was compared to shipping routes and areas with various forms of hydrocarbon development with the aim of highlighting areas of special concern for conservation (reeves et al. 2014). measures suggested in this study to reduce impacts of human activities included: careful planning of ship traffic lanes and ship speed restrictions; temporal or spatial closures of areas where critical processes for whales such as calving, calf rearing, resting or intense feeding take place; strict regulation of seismic surveys and other sources of loud underwater noise and close and sustained monitoring of whale populations in order to track their responses to environmental disturbance (reeves et al. 2014). climate change the arctic is warming faster than any place on earth, and the barents sea has experienced the greatest reduction in sea ice in the arctic, with the period when sea ice is present lessening by more than 20 weeks from 1979 to 2013 (laidre et al. 2015). this will obviously have impacts on ice-associated marine mammals in this area, including white whales, if they are not able to respond rapidly to the ongoing changes in their habitats (learmonth et al. 2006; kovacs & lydersen 2008; kovacs et al. 2011; laidre et al. 2015; descamps et al. 2017). sea ice provides shelter during storms that is likely important to young animals. in addition, it provides protection from open-water predators such as killer whales. killer whales are a serious threat to white whales in areas where there is little sea ice. changing food webs is likely to impact food availability; the white whale’s primary prey species in svalbard, polar cod (dahl et al. 2000), is already declining in the barents sea region, concomitant with reductions in sea ice. additionally, melting and retraction of glaciers is shrinking key feeding areas in front of tidewater glaciers, though white whales seem to be showing some plasticity and may already be feeding on atlantic prey species given that they seem to be spending some time out in the fjords in recent years (hamilton et al. 2019). intensified impacts of contaminants in a warming arctic are also a concern given the already high levels of toxins in svalbard white whales (see earlier; andersen et al. 2001; wolkers et al. 2004; andersen, foreid et al. 2006; wolkers et al. 2006; villanger et al. 2011) and the evidence of impacts on other more southerly populations in the past (see lebeuf et al. 2014). heightened disease risks are yet another threat as new species shift their distributions northward and introduced diseases may survive in a warmer arctic marine environment, which was previously inhospitable (vanwormer et al. 2019). another unknown is potential negative impacts from increased underwater noise from ship traffic and industrial activities such as seismic exploration on the distribution, health and welfare of the white whales in svalbard (reeves et al. 2014; norman et al. 2015). the small size of this population is in itself a concern (see hobbs et al. 2015), particularly in a changing environment, because small populations tend to have lower resilience. acknowledgements the authors thank all the colleagues who have contributed to norwegian polar institute’s white whale research programme over the years in all aspects of the work, from planning and conducting fieldwork through laboratory work, data analyses and manuscript writing. olof bengtsson constructed fig. 2 and ensured that the manuscript was submitted to the journal by the deadline set for the special cluster, while the authors were in the field and offline. references andersen g., foreid s., skaare j.u., jenssen b.m., lydersen c. & kovacs k.m. 2006. levels of toxaphene congeners in white whales (delphinapterus leucas) from svalbard, norway. science of the total environment 357, 128–137, doi: 10.1016/j.scitotenv.2005.05.014. andersen g., kovacs k.m., lydersen c., skaare j.u., gjertz i. & jenssen b.m. 2001. concentrations and patterns of organochlorine contaminants in white whales (delphinapterus leucas) from svalbard, norway. science of the total environment 264, 267–281, doi: 10.1016/s0048-9697(00)00765-8. andersen m., gwynn j.p., dowdall m., kovacs k.m. & lydersen c. 2006. radiocaesium (137cs) in marine mammals from svalbard, the barents sea and the north greenland sea. science of the total environment 363, 87–94, doi: 10.1016/j.scitotenv.2005.06.019. bengtsson o., lydersen c., kovacs k.m. & lindström u. 2020. ringed seal (pusa hispida) diet on the west coast of spitsbergen, svalbard, norway. polar biology 43, 773–788, doi: 10.1007/s00300-020-02684-5. birkeland a., kovacs k.m., lydersen c. & grahl-nielsen o. 2005. transfer of fatty acids from mothers to their calves during lactation in white whales (delphinapterus leucas). marine ecology progress series 298, 287–294, doi: 10.3354/meps298287. brody p.f. 1989. the white whale delphinapterus leucas (palls, 1779). in s.h. ridgway & r. harrison (eds.): handbook of marine mammals. vol. 4. river dolphins and the larger toothed whales. pp. 119–144. london: academic press. castellote m., leeney r.h., o’corry-crowe g., lauhakangas r., kovacs k.m., lucey w., krasnova v., lydersen c., stafford k.m. & belikov r. 2013. monitoring white whales (delphinapterus leucas) with echolocation loggers. polar biology 36, 493–509, doi: 10.1007/s00300-012-1276-2. dahl t.m., lydersen c., kovacs k.m., falk-petersen s., sargent j., gjertz i. & gulliksen b. 2000. fatty acid composition of the blubber in white whales (delphinapterus leucas). polar biology 23, 401–409, doi: 10.1007/s003000050461. descamps s., aars j., fuglei e., kovacs k.m., lydersen c., pavlova o., pedersen a.ø., ravolainen v. & strøm h. 2017. climate change impacts on wildlife in a high arctic archipelago—svalbard, norway. global change biology 23, 490–502, doi: 10.1111/gcb.13381. finley k.j., miller g.w., davis r.a. & green c.r. 1990. reactions of belugas, delphinapterus leucas, and narwhals, monodon monoceros, to ice-breaking ships in the canadian high arctic. canadian bulletin of fisheries and aquatic sciences 224, 97–117. fløystad i.m.b. 2012. an analysis of the population structure of white whales (delphinapterus leucas) in svalbard. msc thesis, university of oslo. freitas c, kovacs k.m., lydersen c. & ims r.a. 2008. a novel method for quantifying habitat selection and predicting habitat use. journal of applied ecology 45, 1213–1220, doi: 10.1111/j.1365-2664.2008.01505.x. freitas c., lydersen c., fedak m.a. & kovacs k.m. 2008. a simple new algorithm to filter marine mammal argos locations. marine mammal science 24, 315–325, doi: 10.1111/j.1748-7692.2007.00180.x. gjertz i. & wiig ø. 1994. distribution and catch of white whales (delphinapterus leucas) at svalbard. meddelelser om grønland, bioscience 39, 93–97. hamilton c.d., vacquié-garcia j., kovacs k.m., ims r.a. & lydersen c. 2019. contrasting changes in space use induced by climate change in two arctic marine mammal species. biology letters 15, article no. 20180834, doi: 10.1098/rsbl.2018.0834. hansen m., villanger g.d., bechshøft t., levin m., routti h., kovacs k.m. & lydersen c. 2017. circulating thyroid hormones and associated metabolites in white whales (delphinapterus leucas) determined using isotope-dilution mass spectrometry. environmental research 156, 128–131, doi: 10.1016/j.envres.2017.03.027. heide-jørgensen m.p. & teilmann j. 1994. growth, reproduction, age structure and feeding habits of white whales (delphinapterus leucas) in west greenland waters. meddelelser om grønland, bioscience 39, 195–212. hobbs r.c., reeves r.r., prewitt j.s., desportes g., breton-honeyman k., christensen t., citta j.j., ferguson s.h., frost k.j., garde e., gavrilo m., ghazal m., glazov d.m., gosselin j.-f., hammill m., hansen r.g., harwood l., heide-jørgensen m.p., inglangasuk g., kovacs k.m., krasnova v.v., kuznetsova d.m., lee d.s., lesage v., litovka d.i., lorenzen e.d., lowry l.f., lydersen c., matthews c.j.d., meschersky i.g., mosnier a., o’corry-crowe g., postma l., quakenbush l.t., shpak o.v., skovrind m., suydam r.s. & watt c.a. 2019. global review of the conservation status of monodontid stocks. marine fisheries review 81(3–4), 1–53. hobbs r.c., wade p.r. & shelden k.e.w. 2015. viability of a small, geographically-isolated population of beluga whales: the effects of hunting, predation, and catastrophes in cook inlet, alaska. marine fisheries review 77, 59–88, doi: 10.7755/mfr.77.2.4. hoguet j., keller j.m., reiner j.l., kucklick j.r., bryan c.e., moors a.j., pugh r.s. & becker p.r. 2013. spatial and temporal trends of persistent organic pollutants and mercury in beluga whales (delphinapterus leucas) from alaska. science of the total environment 449, 285–294, doi: 10.1016/j.scitotenv.2013.01.072. hop h., pearson t., hegseth e.n., kovacs k.m., wiencke c., kwasniewski s., eiane k., mehlum f., gulliksen b., wlodarska-kowalczuk m., lydersen c., weslawski j.m., cochrane s., gabrielsen g.w., leakey r., lønne o.j., zajaczkowski m., falk-petersen s., kendall m., wängberg s.-å., bischof k., voronkov a.y., kovaltchouk n.a., wiktor j., poltermann m., di prisco g., papucci c. & gerland s. 2002. the marine ecosystem of kongsfjorden, svalbard. polar research 21, 167–208, doi: 10.1111/j.1751-8369.2002.tb00073.x. isachsen g. 1921. folk, fangst og færder, nordmændene paa spitsbergen og ishavet. (people, hunting and travels; norwegians on spitsbergen and the arctic ocean.) det norske geografiske selskabs aarbok 28–30 (1916–1919), 121–250. jensen s.k., aars j., lydersen c., kovacs k.m. & åsbakk k. 2010. the prevalence of toxoplasma gondii in polar bears and their marine mammal prey: evidence for a marine transmission pathway? polar biology 33, 599–606, doi: 10.1007/s00300-009-0735-x. karlsen j., bisther a., lydersen c., haug t. & kovacs k.m. 2002. summer vocalisations of adult male white whales (delphinapterus leucas) in svalbard, norway. polar biology 25, 808–817, doi: 10.1007/s00300-002-0415-6. kovacs k.m. & lydersen c. 2008. climate change impacts on seals and whales in the north atlantic arctic and adjacent shelf waters. science progress 91, 117–150, doi: 10.3184/003685008x324010. kovacs k.m., lydersen c., overland j.e. & moore s.e. 2011. impacts of changing sea-ice conditions on arctic marine mammals. marine biodiversity 41, 181–194, doi: 10.1007/s12526-010-0061-0. laidre k.l., angliss r.p., born e.w., boveng p., ferguson s., kovacs k.m., lowry l., lydersen c., moore s., quakenbush l., regehr e.v., stern h., ugarte f., vongraven d. & wiig ø. 2015. a circumpolar assessment of arctic marine mammals, sea ice loss, and conservation challenges in the 21st century. conservation biology 29, 724–737, doi: 10.1111/cobi.12474. learmonth j.a., macleod c.d., santos m.b., pierce g.j., crick h.q.p. & robinson r.a. 2006. potential effects of climate change on marine mammals. oceanography and marine biology 44, 431–464, doi: 10.1201/9781420006391.ch8. lebeuf m., measures l., noel m., raach m. & trottier s. 2014. a twenty-one-year temporal trend of persistent organic pollutants in st. lawrence estuary beluga, canada. science of the total environment 485, 377–386, doi: 10.1016/j.scitotenv.2014.03.097. lønø o. & øynes p. 1961. white whale fishery at spitsbergen. norsk hvalfangst tidende 50, 267–287. lydersen c., assmy p., falk-petersen s., kohler j., kovacs k.m., reigstad m., steen h., strom h., sundfjord a., varpe o., walczowski w., weslawski j.m. & zajaczkowski m. 2014. the importance of tidewater glaciers for marine mammals and seabirds in svalbard, norway. journal of marine systems 129, 452–471, doi: 10.1016/j.jmarsys.2013.09.006. lydersen c. & kovacs k.m. 1999. behaviour and energetics of ice-breeding, north atlantic phocid seals during the lactation period. marine ecology progress series 187, 265–281, doi: 10.3354/meps187265. lydersen c., martin a.r., kovacs k.m. & gjertz i. 2001. summer and autumn movements of white whales delphinapterus leucas in svalbard, norway. marine ecology progress series 219, 265–274, doi: 10.3354/meps219265. lydersen c., nøst o.a., lovell p., mcconnell b.j., gammelsrød t., hunter c., fedak m.a. & kovacs k.m. 2002. salinity and temperature structure of a freezing arctic fjord—monitored by white whales (delphinapterus leucas). geophysical research letters 29, article no. 2119, doi: 10.1029/2002gl015462. norman s.a., hobbs r.c., goertz c.e., burek-huntington k.a., shelden k.e.w., smith w.a. & beckett l.a. 2015. potential natural and anthropogenic impediments to the conservation and recovery of cook inlet beluga whales, delphinapterus leucas. marine fisheries review 77, 89–105, doi: 10.7755/mfr.77.2.5. o’corry-crowe g.m., lydersen c., heide-jørgensen m.-p., hansen l., mukhametov l.m., dove o. & kovacs k.m. 2010. population genetic structure and evolutionary history of north atlantic beluga whales (delphinapterus leucas) from west greenland, svalbard and the white sea. polar biology 33, 1179–1194, doi: 10.1007/s00300-010-0807-y. o’corry-crowe g.m., suydam r., quakenbush l., potgieter b., harwood l., litovka d., ferrer t., citta j., burkanov v., frost k. & mahoney b. 2018. migratory culture, population structure and stock identity in north pacific beluga whales (delphinapterus leucas). plos one 13, e0194201, doi: 10.1371/journal.pone.0194201. o’corry-crowe g.m., suydam r., quakenbush l., smith t.g., lydersen c., kovacs k.m., orr j., harwood l., litovka d. & ferrer t. 2020. group structure and kinship in beluga whale societies. scientific report 10, article no. 11462, 1–21, doi: 10.1038/s41598-020-67314-w. palsbøll p.j., heide-jørgensen m.p. & bérubé m. 2002. analysis of mitochondrial control region nucleotide sequences from baffin bay belugas (delphinapterus leucas): detecting pods or subpopulations? nammco scientific publications 4, 39–50, doi: 10.7557/3.2836. reeves r.r., ewins p.j., agbayani s., heide-jørgensen m.p., kovacs k.m., lydersen c., suydam r., elliot w., polet g., van dijk y. & blijleven r. 2014. distribution of endemic cetaceans in relation to hydrocarbon development and commercial shipping in a warming arctic. marine policy 44, 375–389, doi: 10.1016/j.marpol.2013.10.005. storrie l., lydersen c., andersen m., wynn r.b. & kovacs k.m. 2018. determining the species assemblage and habitat use of cetaceans in the svalbard archipelago, based on recorded observations from 2002–2014. polar research 37, article no. 1463065, doi: 10.1080/17518369.2018.1463065. tittlemier s., borrell a., duffe j., duignan p.j., fair p., hall a., hoekstra p., kovacs k.m., krahn m.m., lebeuf m., lydersen c., muir d., o’hara t., olson m., pranschke j., ross p., siebert u., stern g., tanabe s. & norstrom r. 2002. global distribution of halogenated dimethyl bipyrroles in marine mammal blubber. archives of environmental contamination and toxicology 43, 244–255, doi: 10.1007/s00244-002-1175-6. tryland m., thoresen s.i., kovacs k.m. & lydersen c. 2006. serum chemistry values of free-ranging white whales (delphinapterus leucas) in svalbard. veterinary clinical pathology 35, 199–203, doi: 10.1111/j.1939-165x.2006.tb00114.x. urashima t., sato h., munakata j., nakamura t., arai i., saito t., tetsuka m., fukui y., ishikawa h., lydersen c. & kovacs k.m. 2002. chemical characterization of the oligosaccharides in beluga (delphinapterus leucas) and minke whale (balaenoptera acutorostrata) milk. comparative biochemistry and physiology b 132, 611–624, doi: 10.1016/s1096-4959(02)00083-0. vacquié-garcia j., lydersen c., ims r.a. & kovacs k.m. 2018. habitats and movement patterns of white whales delphinapterus leucas in svalbard, norway in a changing climate. movement ecology 6, article no. 21, doi: 10.1186/s40462-018-0139-z. vacquié-garcia j., lydersen c. & kovacs k.m. 2019. diving behaviour of adult male white whales, delphinapterus leucas, in svalbard, norway. polar research 38, article no. 3605, doi: 10.33265/polar.v38.3605. vacquié-garcia j., lydersen c., marques t.a., aars j., ahonen h., skern-mauritzen m., øien n. & kovacs k.m. 2017. late summer distribution and abundance of ice-associated whales in the norwegian high arctic. endangered species research 32, 59–70, doi: 10.3354/esr00791. vacquié-garcia j., lydersen c., marques t.a., andersen m. & kovacs k.m. 2020. first abundance estimate for white whales (delphinapterus leucas) in svalbard, norway. endangered species research 41, 253–263, doi: 10.3354/esr01016. van parijs s.m., lydersen c. & kovacs, k.m. 2003. sounds produced by individual white whales, delphinapterus leucas from svalbard during capture. journal of the acoustic society of america 113, 57–60, doi: 10.1121/1.1528931. vanwormer e., mazet j.a.k., hall a., gill v.a., boveng p.l., london j.m., gelatt t., fadely b.s., lander m.e., sterling j., burkanov v.n., ream r.r., brock p.m., rea l.d., smith b.r., jeffers a., henstock m., rehberg m.j., burek-huntington k.a., cosby s.l., hammond j.a. & goldstein t. 2019. viral emergence in marine mammals in the north pacific may be linked to arctic sea ice reduction. scientific reports 9, article no. 15569, doi: 10.1038/s41598-019-51699-4. villanger g.d., kovacs k.m., lydersen c., haug l.s., sabaredzovic a., jenssen b. & routti h. 2020. perfluoroalkyl substances (pfass) in white whales (delphinapterus leucas) from svalbard—a comparison of levels in plasma sampled 15 years apart. environmental pollution 263, article no. 114497, doi: 10.1016/j.envpol.2020.114497. villanger g.d., lydersen c., kovacs k.m., lie e., skaare j.u. & jenssen b.m. 2011. disruptive effects of persistent organohalogen contaminants on thyroid function in white whales (delphinapterus leucas) from svalbard. science of the total environment 409, 2511–2524, doi: 10.1016/j.scitotenv.2011.03.014. wolkers h., bavel b., van derocher a.e., wiig ø., kovacs k.m., lydersen c. & lindström g. 2004. congener-specific accumulation and food chain transfer of polybrominated diphenyl ethers in two arctic food chains. environmental science & technology 38, 1667–1674, doi: 10.1021/es030448a. wolkers h., lydersen c., kovacs k.m., burkow i. & van bavel b. 2006. accumulation, metabolism, and food-chain transfer of chlorinated and brominated contaminants in subadult white whales (delphinapterus leucas) and narwhals (monodon monoceros) from svalbard, norway. archives of environmental contamination and toxicology 50, 69–78, doi: 10.1007/s00244-004-0257-z. observations of walruses along the norwegian coast 1967-1992 ian gjertz, gunnar henriksen, torger 0ritsland and bystein wiig gjertz, i . , henriksen, g . , 0ritsland. t. & wiig, 8. 1993: observations of walruses along the norwegian coast 1%7-1992. polar research 12(1), 27-31. extralimital observations of walruses are known to be quite common in norway. the present review covers observations of walruses along the norwegian coast between 1967 and 1992. a total of 34 different walruses have been recorded observed since 1967. these observations indicate a significant increase in the number of walrus observations in recent years, most likely due to an increase in the walrus population in the barents sea area. most of the walruses observed are assumed to be subadult males. i . gjertz and 0. wiig, norwegian polar institute, p . o . box 5072 majorstua, n-0301 oslo, norway; g . henriksen, ofice of the finnmark county governor, deparhnenr of environmental affairs, n-9800 v a h 0 , norway; t . orit~land, institute of marine research, p.o. box 1870 nordnes, n-5024 bergen, norway. introduction atlantic walruses (odobenus rosmarus rosmarus l.) are occasionally observed along the coasts of northern and western europe (see born 1988, 1992 for review) and even as far south as spain (nores & perez 1988). collett (1912), lund (1954) and brun et al. (1968) summarized known observations along the norwegian coast for the period 1900-1967. they suggested that the majority of walruses observed were from the clos est habitats in the barents sea, i.e. svalbard and the coast of russia, and that the apparent increase in walrus observations after 1950 (18 of a total of 31 recorded observations) may partially be due to the walrus protection laws passed in norway in 1952 and in the soviet union in 1956. when norway passed the total protection law in 1952, the walrus population was on the verge of extinction in svalbard (norderhaug 1969). today the population has increased significantly and is believed to number at least one thousand animals (gjertz & wiig 1992). there are also strong indi cations that the svalbard walruses belong to a common svalbard-frans josef land stock (gjertz & wiig 1992). little is presently known about the current status of walruses along the russian coast, but timoshenko & popov (1990) believe the population has remained stable since the pro tection law was passed in 1956. a quarter of a century has passed since brun et al. (1968) published their review of walrus observations from the coast of norway. the aim of the present paper is to document observations of walruses along the norwegian coast in the period 1967-1992 and to discuss whether the recent increase of the walrus population in the barents sea has led to an increase in observations. methods the institute of marine research in bergen, nor way, is often notified when walruses are observed along the norwegian coast and elsewhere. the press also receives similar information. most of this information is stored in a fauna database at the sea mammal section of the institute. this database has provided the basis for this paper. archives of national and local norwegian news papers were also searched for records of past walrus observations along the norwegian coast. little information could be collected for the period prior to 1980, however, because news papers which had suitable archives had switched to electronic archives in the early and middle 1980s. some details of information from the northern county of finnmark were gathered from personal interviews. when the source of reported information was known, relevant data were gathered such as the date, locality and exact position of the obser vation, and any details which would help deter mine the age and sex of the animals (table 1). when the source was unknown, the institute of 28 i . gjertz et al. fig. 1 . location of 53 observations of walruses (including 18 possible resightings and 1 dead walrus) along the norwegian coast 1967-1992. marine research was given as the source. if the observation dates were unknown, the dates of the published sources were given. in cases where the exact month could not be confirmed, a span in months is indicated, for example 03-04 indicates tdal obsbnralions 1967 1992 obbervalions south o( vestfimden observations nocm d veshjwden fig. 2. seasonal and geographic distribution of 34 observations of different walruses along the norwegian coast 1%7-1992. an unknown day in march or april. when the month was known but not the exact day, question marks have been inserted, for example 8007?? indicates an unknown day in july 1980. results no walrus observations were recorded in the years 1967 and 1968. of the total 53 walrus observations recorded (fig. 1, table l ) , eighteen were possible resightings and one was of a dead walrus. thus 34 observations of different walruses were rec orded in the period 1967-1992. most of the obser vations occurred in late winter (january-april) in the area north of vestfjorden (fig. 2). the majority (21) of the observed walruses were classified as subadults on the basis of esti mated tusk length, either from photography or table 1. list of recorded observations of walruses along the norwegian coast 1%%1992. date locality 690225 6903-04 711220 720131 720220 730324 7304-05 73 spring 770623 krampenes, v a d a vardd (city) gjdsundholmen, vigra flakstadvaga, troms valderdy, alesund storsand, hammerfest kiberg, vardd hjelmsciya, masey gulgofjord, tana position 70"m'n 30"lo'e 7053" 31w5'e 60%" 6 w ' e 6t12" 17'22'e 62'30" 6 w ' e 70"41'n 2325'e 70'18" 31"e 71w'n 24'45'e 7cp40'n 28"36'e comments source adult adult, possibly same as 690225 18 months old calf adult young, tusks 1&15 cm, shot dead cow, calf and possibly one other animal 3 swimming walrus, possibly same as 7 w . 5 found dead aftenposten 690228 tor ddvle pen. comm. sunnmdrsposten 7201 17 aftenposten 720201 britsland (1973) frank nilsen pers. comm. line kettunen pers. comm. fritz johansen pers. comm. bjdrn klausen pers. comm. rekstad (1977) walruses along the norwegian coast 1967-1992 29 table 1. continued date locality position comments source bergens tidende 790830 790816 win?? 8101 19 8103-04 810320 810501 810623 810626 810703 8108?? 820214 82031&13 820323 820401 820412 820417 820428 820704 820807 820808 820810 820814 820819 820822 820824 820906 830920 8403?? 8404?? 840829 850216 850920 8701-02 8905-07 900220 910103 910103 10108 910207 910218 910418 9201 18 920401 920430 hammerfest (city) bondbyskjzr, lebesby bokkby, melby ifjord, lebesby fbrlandsfjd. haugesund sigerfjord, hinnby lyngstad, nordmere hvaler, oslofjorden oslofjorden trama eigerby, rogaland oslofjorden sandby, langesundsfjd. brekkestrand, tromby lawonjarg, tana karlsey, troms bbvlg, rennesby grunnfjorden, ringvassoy sletta n 0 of rbver mbkstravl&, hordaland eltravlg, sveio 0lve. hardangerfjorden sbre oyane, 0 s hjellstad, raunefjorden dolvik, hordaland hegvik, lysefjorden ekofisk, nordsjwn skarsvag, nordkapp skarsvlg, nordkapp skarsvlg, nordkapp grunnfarnes, torsken rolvsbya, mlsoy breiviklandet, hasvik gjessvax, nordkapp sifjord, senja nervei, gamvik myre, vesteralen andenes, andeya nervei, gamvik torhop, tana simavag, skjervby smalfjord, tana lyngen eidkjosen, tromsb 7v40'n 2399'e 70"30'n 26'45'e 66'50'n 1370'e 70"30" 27"e 5995" y15'e 68'37" 15"u'e 6 2 3 " 7"20'e 59"n 11"e 59yo'n 10w'e 66"30" 12"e 59"n 5"we 59"10" 10'40'e 5tn y40'e 5827" 8'51'e 70"30'n 28"30'e 70"ol'n 19"34' 59'06" 5'43'e 70"02'n 18'57'e 5996'e s"05'e 59"33'n 5'30'e 59"40'n s"23'e 59'59'n 5'46'e w08'n 525'e w15'n 1s'e w19'n s"15'e 59'" 623'e 56"n 2"40'e 71"07'n 25%'e 71"07'n 25"46'e 71'07" 25'46'e 69%" 16"58'e 70%" 24"e 70"u)'n 22'11'e 7lo06'n 2521'e 69"15'n 1t05'e 70"40'n 27"52'e 68%" 15'03'e 69"19'n 16"ls'e 70"40'n 27"52' 70"30'n 28"e 70"n 21"e 70"26'n 28ti3'e 69"50'n 30"e adult male only one 20 cm tusk two 20 cm tusks tusks 15-2ocm subadult subadult, possibly same as 810626 subadult subadult male possibly same as 820214 subadult, tusks 10cm. possibly same as 820214 subadult, possibly same as 820214 tusks aprx. 20 cm subadult, possibly same as 820214 tusks 10-15 cm possibly same as 820906 possibly same as 820906 tusks 20 an, possibly same as 820906 possibly same as 820906 possibly same as 820906 possibly same as 820906 possibly same as 820906 subadult male, shot subadult male, tusks 20 cm two year old calf possibly cow and two year old calf. same as 8403?? two year old calf, same as 8403?? this calf stayed in the area until 860428 tusks present tusks 10-12 cm tusks 10-20 cm tusks 50 cm adult male tusks 30 cm, on shore adult male, possibly same as 910103 tusks 15-20cm possibly same as 910207 adult male subadult two animals subadult olav 0.01sen pers. comm. nordlands framtid 810119 roald erlandsen pers. comm. haugesund avis 810321 institute of marine research lofotposten 810630 vg 810625 vg 810626 vg 810703 institute of marine research stavanger aftenblad 820304 mathiasson (1983) institute of marine research agderposten 820401 dagbladet 820403 per aleksandersen pers. comm. vg 820417 stavanger aftenblad 820428 nordlys 820708 institute of marine research institute of marine research institute of marine research bergens tidende 820816 bergens tidende 820820 bergens tidende 820824 bergens tidende 820825 bergens tidende 820906 stavanger aftenblad 830920 sunmbrsposten 830920 alfon slettvold pers. comm. dagbladet 840829 dagbladet 840829 vg 840829 alfon sletwold pers. comm. nordlys 850216 rolf hesjevik pen. comm. hlkon holst-olsen pen. comm. dagfinn jensen pen. comm. nordlys 900220 dagbladet 900220 institute of marine research institute of marine research andbyposten 9101 10 finnmarken 910207 eivind pettersen pers. comm. nordlys 910418 finnmarken 920121 norwegian radio (nrk) local transmission vg 920502 30 i . gjertz et al. personal comments from the observers. nine walruses were classified as adults, two of which were females with calves. the remaining four were unclassified due to insufficient information. discussion according to brun et al. (1968) at least 31 walrus observations were recorded along the norwegian coast in the period 1900-1967. eighteen of these were observed after 1950, and it was suggested that this increase was due to the ban on walrus hunting which was passed in the 1950s by both norway and the ussr. these 18 observations plus the 34 observations of our study for the period after 1967 give a total of 52 (approximately 80%) of the 65 walrus observations along the coast of mainland norway after 1950. born (1988) hypothesized that this increase has been caused by a combination of climatic changes and a popu lation increase in the western soviet arctic and the svalbard region. in the years since 1967 human living patterns, particularly along the coastal areas of northern norway, have changed. large tracts of the north ern coasts are now more or less uninhabited. the once large coastal fishing fleet has also been sig nificantly reduced in size. this implies that fewer people frequent the more isolated parts of the coasts. the increasing number of walrus obser vations in recent years, possibly through lesser effort, i.e. fewer observers, therefore suggests that the number of walruses is increasing. it is also important, however, to remember that an increased public interest in conservation and wild life may have been responsible for a higher inci dence of walrus observations reaching the media. according to brun et al. (1968) the months with most sightings of walruses on the norwegian coast were july and october. we, however, found that most of the observations were recorded in late winter. the reason for this apparent seasonal shifting is not clear. most of the observations from our review for the period from january april are from northern norway. the nearest known walrus habitats are found in the area from the white sea to kolguev in northern russia and the svalbard coastal areas. according to boloborodov & timoshenko (1974) the walruses are found at kolguev in january and february, implying that this is a wintering area. some walruses could easily swim the relatively short distance to northern norway, which would explain the large number of observations from january to april. it is known that walruses often make swift long journeys in autumn and winter from svalbard to the neighboring frans josef land (wiig & gjertz 1991). they should there fore have little difficulty in swimming to mainland norway. the apparent increase in the number of walruses, at least in the svalbard regions (gjertz & wiig 1992), may be responsible for the increase in the number of walruses visiting the coast of mainland norway at this time of the year. several authors have discussed the possible ori gin of extralimital walruses sighted in european waters (ritchie 1921; jensen 1927; brun et al. 1968; born 1988). ritchie (1921) and jensen (1927) hold that walruses observed in the u.k. and northern europe come originally from greenland. as most of the observations in nor way are from the northern coasts, it is most likely that these animals come from northern russia or svalbard (brun et al. 1968; born 1988). we have used information on tusk lengths to indicate the sex and age of the animals (see fay 1982). based on this criterion, 21 of the 34 dif ferent walruses observed were considered to be subadults; nine adults of which four were males. only two adult females had been observed. the difficulty in distinguishing between females and subadult males may bias these results. however, mercer (1967) found no females among the extra limital walruses recorded in newfoundland. simi larly ritchie (1921) and brun et al. (1968) found a predominance of males among the walruses recorded in their reviews. it is therefore possible that extralimital migrations are affected by sexual differences in behaviour (see greenwood 1983). by comparison we seem to have recorded fewer adult males and more sub-adult animals than brun et al. (1968). this may be due to inaccuracies in the estimations of tusk lengths. due to the increasing numbers of walruses in the barents sea area and an increased awareness and interest among the public, we expect the number of extralimital sightings of walruses vis iting the norwegian coast to increase in coming years. references beloborodov, a. g. & timoshenko, l. k. 1974: in defence of the atlantic walrus. priroda 3.97-99 (trans]. ser. mar. sew. can. 3812 (1976)). walruses along the norwegian coast 1967-1992 31 born, e. w. 1988: hvalrosstrejfere i europa. flora og fauna (arhus) 94, 9-14. born, e. w. 1992: odobenus rosmarus linnaeus, 1758 walross. pp. 268-299 in duguy, r. & robineau, d. (eds.): handbuch der saugeriere europar. band 6: meersauger, teil 11: robben pinnipedia. aula-verlag, wiesbaden. brun, e., lid, g. & lund, h. m. k. 1968: hvalross, odobenus rosmarus, pa norskekysten. fauna (oslo) 21,7-20. collett, r. 1912: norges panedyr. h. aschehoug & co., kri stiania. fay, f. h. 1982: ecology and biology of the pacific walrus. odobenus rosmarus divergens illiger. u.s. fish. wildl. ser. norrh a m . fauna 74, 1-279. gjertz, i. & wiig, 0. 1992: feeding of walrus odobenus ros marus in svalbard. polar rec. 28, 57-59. greenwood, p. j. 1983: mating systems and the evolutionary consequences of mating. pp. 116-131 in swingland, 1. r. & greenwood, p. j. (eds.): the ecology of animal mouemen?. claredon press, oxford. jenson, a. s. 1927: hvalrossen ved skagen og dens van dringsveje. narurens verden (junijuli) , 1-5. lund, h. m. k. 1954: the walrus (odobenus rosmarus (l.)) off the coast of norway in the past and after the year 1900, together with some observations on its migrations and “cruis ing s p e e d . astarre 8, 1-12. mathiasson, s. 1983: valrossen-shusynt, kulturhistoriskt inter essant arktisk past vid vastkusten. fauna och flora (srock.) 78, 253-261. mercer, m. c. 1%7: records of the atlantic walrus, odobenus rosmarus rosmarus, from newfoundland. j . fish. res. bd. canada 24, 2361-2634. norderhaug, m. 1%9: hvalrossens (odobenus rosmurus) fore komst i svalbardomridet 1960-1%7. norsk polarins?. arbok 1%7, 146-150. nores, c. & perez, c. 1988: the occurrence of walrus (odo benus rosmarus) in southern europe. 1. 2001. (lond.) 216, 593-5%. 0ritsland. t. 1973: walrus in the svalbard area. iucn pub lications new series supplementary paper 39, 59-68. rekstad, a. 1977: dsd hvalross i gulgofjorden, finnmark. fauna 30, 238. ritchie, j. 1921: the walrus in british waters. scottish naruralis? timoshenko, yu. & popov, l. a. 1990. on predatory habits of atlantic walrus. pp. 177-178 in fay, f. h., keuy, b. p. and fay, 9 . a. (eds.): the ecology and management of walrus populations. marine mammal commission report pb91-100479, washington. wiig, 0. & gjertz, i. 1991: satellite telemetry of walrus at svalbard. abstract, ninth biennial conference on the biology of marine mammals, december 5-9, 1991, chicago. (1921), 5-9, 77-86. studies of sea surface temperatures in selected northern norwegian fjords using landsat tm data m. haakstad. j . w. kogeler and s. dahle. haakstad, m., kogeler. j . w. & dahle, s. 1994: studies of sea surface temperatures in selected northern norwegian fjords using landsat tm data. polar research 13, 95-103 remote sensing is evaluated as a tool for studying oceanographic phenomena. data from the infrared channel of thematic mapper onboard landsat 5 were used to map the spatial distribution of sea surface temperatures in selected fjords in northern norway. sea surface temperature charts provided clear indications of surface current patterns, upwellings, convergences, etc. the complex pattern of currents found in fjords is, t o varying degrees, affected by tides and fresh water run-off, as well as by hydrographic, meteorological and topographical conditions. in northern norway the surface circulation is strongly influenced by inland cold air flows during prolonged periods of cold weather. this study demonstrates that remotely sensed data can be used as an important supplement to traditional hydrographical and meteorological observations in order to understand the distribution of temperatures and circulation patterns in the surface layers of fjords and coastal waters. m . haahtad, school of fisheries and aquaculture nordland college, n-8002 bod@, norway; j . w . kogeler and s. dahle, akvaplan-niva ais, p. 0. box 735, n-woi t r o w ) , norway. introduction the fjords in the area covered by this survey the coast of norway is indented by numerous fjord inlets. not all of these fit the classical defi nition of a fjord given by pritchard (1952): an elongated indenture of the coastline containing a relatively deep basin with a shallow sill at the mouth. this geomorphological definition excludes some of the northernmost fjords, which have no sills. later classifications take into account other parameters such as circulation and hydrography. however, the important matter in this context is that a fjord is a glacially cut coastal structure which penetrates from the coast into the mountainous norwegian landscape. in addition to geomorphology, freshwater runoff, climate, tide and exchange processes with the coastal ocean influence the circulation and hydrography of fjords. since all these parameters vary along the norwegian coast, fjord circulation and hydrography tend to be very different even in remain weakly stratified even in the coldest months of the year (molvaer et al. 1984; haakstad 1984). however, because salinity is more impor tant than temperature in determining the density of cold water, there may be temperature gradients even if the stability is very weak. in late winter the surface layer is usually cold, while the inter mediate and deep waters are considerably warmer and more saline. upwelling and vertical mixing, therefore, are easy to detect as aberrations in surface temperature. remote sensing can be an appropriate method for studying the winter surface temperature and circulation in fjords and coastal regions (kogeler & dahle 1991). in this paper satellite observed sea surface temperature (sst) is compared with the sea surface temperature distribution expected from the observed wind at the meteorological stations in the study area. neighbouring fjords. in the northernmost part of norway the strati fication is completely broken up during winter, material and methods with vertical convection from top to bottom and a homogeneous temperature in the coldest satellite imagery and processing i months of the year; february, march and april (saelen 1950; eilertsen et al. 1981; nordgaard et al. 1982). the area surveyed for this study has a complex and differentiated topography. a thermal infra redsensor with high spatial resolution is required 96 m . haakstad et al. to obtain reliable satellite data over areas with narrow fjords, sounds, inlets, small islands and extensive skemes. for this reason the landsat thematic mapper (tm) instrument was chosen for use. the landsat-tm instrument has 6 bands with 16 sensors per band, each with a ground field view (gfv) of 30 m. the thermal band (band 6), however, has only four sensors, each with a gfv of 120 m. in order t o make band 6 images overlap with images from other spectral bands, each ther mal pixel is usually duplicated three times in both sample and line direction. this means that pure pixels, i.e. pixels with information that is not contaminated by temperatures over land areas, can only be found in waters wider than 120m. consequently, reliable thermal data can only be found over waters wider than 240 metres. weather observation reports obtained from the norwegian meteorological institute (dnmi), and "quick-looks" (photographic presentations of satellite raw data acquired in the visible range of the solar spectrum) from another sensor onboard landsatd (multi spectral scanner, mss) were used to eliminate scenes with such disturbing elements as clouds and fog. two tm scenes were selected for this study. the scenes covering an area of 185 km x 370 km (64 1/2" to 68" n) were acquired on 6 march 1987. however, this paper only deals with a minor part of the entire area. the data discussed in this paper are from the area indicated with a rectangle in fig. 1. the landsat-5 tm computer compatible tapes were ordered from the esa (european space agency) earthnet station in sweden and pro cessed at tromse satellite station in norway. data processing was performed on a 12s inter active image processor (international imaging systems, system 600) running on a uvax i1 host computer. information from land and sea areas was separated using band 4 (near infra-red) data. the periodic striping across the thermal data set was partly removed through histogram modi fication, which is a simple gain and bias model which does not significantly modify the resultant pixel values. as there is no reliable calibration algorithm developed for landsat (tm) thermal data, a colour-coded sea surface temperature scale was designed using a regression equation between pixel values and in situ temperatures. after a thermal image had been colour-coded, it was merged with a band 4 black and white image of land and ice areas, thus making it possible to norw~gian se(a 70' 66' 60' i* 10' 1s. 20' 2s' g. 1 . geographical coverage of the data set applied in this report. the rectangle defines the remote sensed area discussed in this report. delineate ice-covered waters and geomorpho logical features. finally the images were geo metrically corrected. in situ sea surface temperatures were measured in the upper 3 m and within 6 hours of the landsat over-pass. data were obtained from 21 fish farms, an automatic measurement buoy, and from a ship equipped with thermograph. the temperature measurements were evalu ated with respect to accuracy, reliability and local conditions. unreliable data and data collected from areas that were clearly affected by clouds or freshwater run-off were excluded, leaving 27 in situ measurements for calibration purposes. no hydrographic depth profiles taken simul tanous with the satellite observations were avail able. however, the general hydrography of these fjords is relatively well known from earlier obser vations (molvaer et al. 1984; haakstad 1984). mptpnrnlnpirnl dntn 0------.. - for at least one month preceding satellite over pass, meteorological charts and detailed obser studies of sea surface temperatures in selected northern norwegian fiords using landsat t m data 97 vation series for wind strength and direction, air and sea surface temperatures, and humidity and precipitation were available. climatological data were also obtained from all the meteorological observation stations in the study area (dnmi, unpubl. reports). wind data are based on wind observations from the meteorological stations established by the norwegian meteorological institute. some of these stations take 3 observations per day, while others take 4 equispaced observations per day. seven meteorological stations measured wind in the study area during the winter of 1987; one offshore station, three in the ranfjord area, and three in the skjerstadfjord/saltenfjord area. these meteorological stations covered the entire area from the innermost fjord to the coastal area beyond the fjord. wind stress on the sea surface in winter, wind is the dominant force effecting fjord circulation. therefore it is important to obtain a good estimate for the energy transfer from the atmosphere to the ocean. in order to do so, it is important to have a realistic value for the drag coefficient (cd). in this paper the drag coefficient given by smith (1980) is used: w 5 6 4 s 6 4 s < w i 2 2 4 s (1) (0.61 + o.o63(wl) 1000 cd = where w is the wind speed (m/s) in 10 metres. the duration of a certain wind field is of great importance. in order to visualize the duration and stability of the windfield, the accumulated daily mean wind stress w, (in direction a) is calculated as follows: w, = z t with: 1 " n ; , 1 t = c t; zl = it( cos(/3 a) t = c@nlw(w where n is the number of observations per day, /3 is the downwind direction, and pa is the air density. results in the central part of the ranfjord, water-land separation was not completely accurate. however, in the rest of the area land and water are separated correctly. in situ temperatures ranged from 0.9 to 4°c. pixel values in the raw data varied from 78 to 85 (on a scale of 0 to 255). the correlation coefficient for the correspondence between satellite pixel values and in situ sea surface temperatures was 0.95. the sea surface temperature image made from the satellite data is shown in fig. 2. based on the satellite imagery the study area may be divided into three regions: an offshore area with high sea surface temperature, a coastal zone with low sea surface temperature, and the fjords where there is considerable variation in sea surface temperature. the inner parts of some of the shorter fjords have common sea surface temperatures nearly as high as the offshore water masses, while others have a sea surface tem perature close to freezing. the fjords discussed in this paper are all deep sill fjords, with the exception of skjerstadfjord, which has a shallow sill. the deepwater beneath sill depth may be stagnant for long periods of time and will never come to the surface of the fjord. none of the fjords discussed in this paper have a distinct layered structure and the stability of the entire water mass is very weak in winter. a typical depth profile for the hydrography of one of these fjords in late winter is shown in fig. 3. the temperature and salinity increase slightly with depth. this depth-dependent temperature variation makes it possible t o identify the atypical watermasses on sst maps where wind brings subsurface watermasses t o the surface. the meteorological situation before and during the satellite observations air movements are complicated in fjords and coastal areas making it difficult to find wind observation sites representative of large areas. however, in winter, prolonged periods with high pressure over scandinavia can occur. during such periods the wind pattern is stable. in open areas the direction of the surface wind with respect to the surface isobars is on the order of less than 20" to the left of the isobars ( b ~ r r e s e n 1987). inland the wind is down-fjord. but, on the coast the wind direction is more variable. the sst map for 6 march (fig. 2) is from the end of such a period. 98 m. haakstad et al. -. . -. fig. 2. remotely sensed sea surface temperature, 6 march, 1987. the surface pressure chart for 12 utc on 2 march, 1987 is representative of the pressure over northern scandinavia during the period from the end of february t o 6 march, 1987 (deutscher wetterdienst 1987), fig. 4. the daily mean wind at the meteorological stations in the study area on 2 march is shown in fig. 5. during winter periods with high pressure over scandinavia, a surface layer of cold air forms and drains to the coastal area through t h e valleys and fjords. such mountain-lee gravity wave winds were sfudied by macklin et al. (1988). they con cluded that a geotriptic (geotriptic is the balance between pressure gradient, coriolis force, and frictional forces, johnson (1966)) adjustment of the regional surface wind field is nearly achieved studies of sea surface temperatures in selected northern norwegian fiords using landsat t m data 99 2 a 6 t 32 33 34 350100 25 26 27 0 25 e g50 75 , *t 0 e . 25 . 75 r s 0 25 50 75 . salinity 100 i 100 i 100 . fig. 3. typical vertical profiles for temperature, salinity and density (glomfjord, n 66" 49,5' e 13" 39', on 17 march 1981). within a distance from the mountain barrier cor responding to the rossby radius of deformation (r): f r = (3) where h is the boundary layer thickness, 0-6, is the inversion strength, 0, is the average potential temperature in the boundary layer, f is the cori fig. 4. surface pressure (hpa) 12 utc, 2 march 1987. olis parameter, and g is the acceleration due to gravity. the temperature inversion is easily identified on the plot of the vertical atmospheric tem perature profile for bod0 on 2 march (fig. 6). however, the temperature increases again towards the ground, probably because the air passing bod0 has been eroded by a heat transfer when flowing out the skjerstadfjord/saltenfjord (the air temperature on the ground in saltdal was below -10°c on the 2 march). fig. 6 indicates that a reasonable estimate for the boundary layer thickness is 800-1200 metres. accordingly, a reasonable estimate for the rossby radius is between 110 and 140 km. since the pressure gradient has an orientation nearly perpendicular t o the coast, the coriolis force will gradually turn the wind to a more long shore direction off the coast. due to friction the wind will not become completely parallel to the isobars. however, at offshore length scales exceeding the rossby radius the wind will be inclined less than 20" to the large-scale pressure pattern. the wind pattern in fig. 5 is in agreement with this theory. the wind on 2 march is responsible for most pronounced wind stress in the time period prior to the satellite observations and therefore probably responsible for the most of the observed anom alies in the sst maps. the accumulated daily mean wind stress for the meteorological stations covering the area from the valley inside the fjord to the coastal area outside the fjords are presented in figs. 7 and 8. these figures demonstrate the 100 m. haakstad et al. p c rssl 0 \ myken p i \ i . 66' mufc 12 utc fig. 5. daily mean wind in the study area, 2 march 1987 (fjord names in italics). fig. 6. vertical temperature profiles from bode, 2 march 1987 (radiosonde profile). studies of sea surface temperatures in selected northern norwegian f o r d s using landsat t m data 101 -0,3 february march - -'*i i saltdal -0,2 2 2 2 3 2 4 2 5 2 6 2 7 2 8 1 2 3 4 5 6 0,l 0 -0,l -0,2 -0,3 -0,4 -0,5 -0,6 -0,7 i -+wincistress from west bod# 2 2 2 3 2 4 2 5 2 6 2 7 2 6 1 2 3 4 5 6 fig. 7. wind stress at saltdal, bode. and tennholmen, 22 f e b r u a r y 4 march 1987. 102 m. huukstud et al. 0 -0,l -0,2 -0,3 -0,4 -0,5 february - - - - - - march a" \ nerdal -0,2 i 1 i i + windstress from south-west windstress from north-west -03 t 2 2 2 3 2 4 2 5 2 6 2 7 2 8 1 2 3 4 5 6 0,l i * windstress from south windstress from west 2 2 2 3 2 4 2 5 2 6 2 7 2 8 1 2 3 4 5 6 0 -0,l -0,2 -0,3 -0,4 myken studies o f sea surface temperatures in selected northern norwegian fiords using landsat tm data 103 local variability of the wind in the fjords and the coastal area. this is most noticeable in the saltenfjord/skjerstadfjord area, where the wind decreases both seaward and in the valley beyond the fjord. discussion as thermal infrared radiation is emitted from the very surface layer, remote sensing data must be treated with great care, especially when there is reason to assume that the surface water is strati fied. a thin surface layer is generally stratified shortly after precipitation or solar warming and in areas influenced by fresh water run-off. during periods with great heat loss from the sea surface, the temperature of a thin surface layer may be lower than the average temperature of the surface layer as measured in the usual way (fedorov & sklyarov 1981). it must also be taken into account that local fog can occur where warm and cold air meet. fog and haze produce artifacts which can show up as area with low sea surface tempera tures. the imagery was acquired at 10 am (utc) on 6 march, when the sun angle in northern norway was still low. therefore solar radiation will not have influenced sea surface temperatures. also, no precipitation which could result in lay ering of the water was recorded during the days prior to the satellite overpass. comparison of the satellite maps and the expected fjord circulation. only a few fjords in the mapped area are suf ficiently covered by meteorological observations and available hydrographical data. four fjords have been chosen for a more thorough discussion in this paper: ranfjord, sjonfjord, glomfjord and skjerstadfjord (fig. 5). freshwater supply is an important determinant of fjord circulation. much of the freshwater supply to norwegian fjords is regulated and utilized for hydro power. three of the selected fjords have a large freshwater supply in winter, skjerstadfjord/saltenfjord, glomfjord, and ranfjord. the freshwater supply to sjonfjord is also regulated, but the freshwater discharge in winter is very low. in late winter the “freshwater fjords” usually have a cold and low saline surface layer, while temperature and salinity increase slightly with depth. figs. 7 and 8 show that the wind direction was constantly down-fjord during the week prior to the satellite over-pass. under such conditions sur face water is transported away from the inner part of the fjord and subsurface water is brought up to the surface. this upwelling of warmer inter mediate water is clearly visible on the sst maps through a higher temperature. this effect is seen in most of the fjords depicted in fig. 2. however, in some fjords there is no upwelling at the head of the fjord. skjerstadfjord is a special case because of its shallow and narrow entrance, saltstraumen. this narrow entrance causes a considerable tidal chok ing, energetically mixing the water as it passes the entrance. this narrow entrance also has a blocking effect on the wind transport out of the fjord. fig. 2 shows how the cold surface water accumulates in the outer part of skjerstadfjord, causing an abrupt increase in temperature between skjerstadfjord and saltenfjord. the hydrography in glomfjord is relatively well known (molvaer et al. 1984). the remotely sensed sea surface temperature in the central part of the fjord, 6 march 1986, is very similar to the sea surface temperature in the typical depth profile presented in fig. 3. in glomfjord there is no upwelling in the inner part of the fjord, probably because the wind effect is much weaker in this fjord than in skjerstadfjord. there are no wind observations from the glomfjord area but the indication of light wind is in agreement with the local knowledge about the wind in this area. this area is regarded as considerably less exposed t o this kind of wind than skjerstadfjord and saltenfjord (sandmo 1990). there is a weak upwelling in the inner part of ranfjord. ranfjord is a long and channel-shaped fjord. however, the steep sides of the fjord are broken up by side valleys crossing over to the surrounding fjords. in this context the passage from the central part of ranfjord to sjonfjord is particularly important. the wind flowing out from ranfjord is obviously drained over to sjonfjord through the passage between the central part of ranfjord and the inner part of sjonfjord. in the inner part of ranfjord the temperature decreases down-fjord to the area where the side of the fjord is broken up by the pass to sjonfjord. a strong upwelling in sjonfjord indicates that some of the air flows from ranfjord pass over to sjonfjord, reinforcing the windfield in that fjord. 104 m. haakstad et al. the coastal ocean during winter periods with high pressure over scandinavia the wind on the coast follows the direction of the fjords or blows perpendicular to the coast. as the air moves offshore, the direction will be more parallel to the isobars. this means that the wind turns gradually to a more longshore direction as the distance from the coast increases. since the ekman transport is to the right of the wind direction, the shoreward component of the transport will increase offshore. in this way the coastal surface water is transported northward and in towards the coast. since cold surface water is transported out of most of the fjords, at the same time as coastal surface water is transported shoreward, there will be a convergence of cold surface water in the coastal zone. this effect is clearly seen in the sst chart presented in fig. 2. concluding remarks the satellite image shows the sea surface tem peratures at the time of the satellite overpass. as weather conditions usually are relatively stable during cold high-pressure periods, it is assumed that the map is representative for the sea surface temperatures during prolonged cold periods. during late winter there are sometimes pro longed periods of high air pressure over scan dinavia. the sst charts presented in this paper represent the situation at the end of one such period. such a weather situation is extremely stable with little variation in the direction of the prevailing winds. many of the differences that show up in the sst charts, therefore, are probably caused by local topographical inferred variation in the wind field. as a result it will require a comprehensive field observation program to pro cure enough wind observations t o obtain the same information as the sst charts give. the cold air produced during a period with high pressure over the scandinavian peninsula will drain out some of the fjords giving down-fjord wind. the winds blowing out of the fjords trans port the cold surface water out of the fjords. off the coast the wind will gradually tend to blow more parallel to the isobars (less than 20" to the left of the isobars). since the offshore isobars during such a weather situation will be nearly longshore, the offshore wind will transport sur face coastal water toward the coast. in this way the coastal zone will be a convergence area for cold water during such a period, if the wind is not too strong. the weather situation discussed in this paper represents a situation where local coastal zone observations cannot give sufficient information, and satellite observed sst can be an easy way to provide supplementary information. acknowledgemenh. the satellite images were processed as part of a survey of sea surface temperatures for aquaculture planning carried out on behalf of the regional development council and the county of nordland. the authors wish to thank n. t . hagen and h. k. marshall for careful reading of and useful comments on this paper. references b ~ r r e s e n , j . a. 1987: wind atlas f o r the north sea and the norwegian sea. the norwegian meterological institute. 183 pp. deutscher wetterdienst 1987: europaischer wetterbericht, vol. 12, nos. 6045. eilertsen, h . c.. falk-petersen, s., hopkins, c. c. e. & tande, k. 1981: ecological investigations on the plankton community of balsfjorden, northern norway. program for the project, study area, topography, and physical environ ment. sarsia 66, 25-34. fedorov, k. n . & sklyarov, v. e. 1981: space oceanography: hopes and realities. pp. 35-47 in gower, j. f. r. (ed.): oceanography from space. haakstad, m. 1984: barhunders~kelse i ranfjorden-en marin industriresipient. hydrografiske undersekelser 1980-1982. norsk institutt for vannforskning, oslo. 48 pp. johnson, w. b., jr. 1966: the "geotriptic" wind. bull. amer. meteor. soc. 47 (9). 982. kogeler, j. w. & dahle, s. 1991: remote sensing of seasurface temperatures for aquaculture in nothern norway. arctic & ( i ) , 34-39. macklin, s. a . , lackmann, g . m. & gray, j . 1988: offshore directed winds in the vicinity of prince william sound, alaska. monthly weather review, 116(6), 1289-1301. molva?r, j., knutzen, j., haakstad, m. & tangen, k. 1984: basisundcm@kelse i glomfiorden 1981-1982. vannuukiji ning, m n k v a l i t e t , miij@gimr i organhmer og organirme smfumn pd grunt u r n . norsk institutt for vannforskning, nordgaard, 0.. normann. u. & pettersen, f. 1982: havmil j0data b a nordnorske fjorder i 1981. trornura 28. t r o r n s ~ museum, university of tromsb. pritchard, d. w. 1952: estuarine hydrography. pp. 243-279 in landsberg, h. e. (ed.): advances in geophysics, vol. i . academic press. sandmo, h . 1990: nedising pa bode havn. vreret14(1), 20-21. smith, s. 1980: wind stress and heat flux over the ocean in gale force winds. 1. phys. oceanogr. 10(5), 7 w 7 2 6 . szlen, 0. h. 1950: the hydrography of some fjords in northern norway. tromsb museums arshefter, nat. hist. avd. vol. 70, no. 38 (1947). oslo. 125 pp. morphological measurements of atlantic puffin (fratercula arctica naumanni) in high-arctic greenland research article morphological measurements of atlantic puffin (fratercula arctica naumanni) in high-arctic greenland kurt k. burnham1, jennifer l. burnham2 & jeff a. johnson3 1high arctic institute, orion, il, usa; 2department of geography, augustana college, rock island, il, usa; 3department of biological sciences, university of north texas, denton, tx, usa abstract morphological measurements of 45 adult atlantic puffins fratercula arctica were collected in high-arctic greenland between 2010 and 2016. measurements support that the population belongs to the f. a. naumanni subspecies and were significantly larger than those from populations found at lower latitudes, including f. a. grabae and f. a. arctica populations. male puffins from high-arctic greenland had greater mass, bill length and tarsus length than females, but no difference was found in wing length. in comparison to other naumanii populations, body size was most similar to puffins in svalbard. overall, the measured atlantic puffins from high-arctic greenland had some of the largest and most variable morphological measurements reported for any studied atlantic puffin population. while morphological measurements and the relative geographic isolation of the puffin population in high-arctic greenland support the naumanni subspecies designation, additional research should use genetic methods to determine if this population and other populations in the north atlantic are isolated. this is the only collection of naumanni morphometric measurements from geographical north america and enhances our collective knowledge of the species. keywords sexual dimorphism; cline; grabae; bergmann’s rule; bird size abbreviations anova: analysis of variance statistical test sd: standard deviation citation: polar research 2020, 39, 5242, http://dx.doi.org/10.33265/polar.v39.5242 copyright: polar research 2020. © 2020 k.k. burnham et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 18 december 2020 competing interests and funding: the authors report no potential conflict of interest. funding was provided by the offield family foundation, wolf creek charitable trust, augustana college, patagonia, university of north texas, trout/jarvis family, cafferty family, kim pelle and additional donors to the high arctic institute. *correspondence to: kurt k. burnham, high arctic institute, 603 10th avenue, orion, il 61273, usa. e-mail: kburnham@higharctic.org introduction the atlantic puffin (fratercula arctica; hereafter referred to as puffin) is a medium-sized auk found in the north atlantic, with a breeding range extending north from the gulf of maine, usa (43°n) and brittany, france (50°n) to north-west greenland (77°n), svalbard, norway (80°n) and novaya zemlya, russia (76°n; fig. 1; gaston & jones 1998; harris & wanless 2011). although the global population is estimated at 12–14 million adults (harris & wanless 2011; berglund & hentati-sundberg 2015), the species is listed globally as vulnerable and currently in decline, with very low productivity reported recently for many breeding colonies (birdlife international 2020). over 90% of the global population is in europe, with iceland and norway accounting for 80% (birdlife international 2020). colony sizes range from a few breeding pairs in the high arctic of eastern north america (e.g., north-west greenland and north-east canada; salomonsen 1950; robards et al. 2000) to over a million in the westman islands, iceland (hansen & garrðarsson 2009); some colonies have significantly decreased in size over the past few decades (e.g., røst, norway; harris & wanless 2011; birdlife international 2020). figure 1 breeding distribution of atlantic puffin (fratercula arctica) and locations of places mentioned in the text and table 2 are as follows. (1) skomer island; (2) isle of may; (3) machias seal island; (4) gull island; (5) gannet islands; (6) baer; (7) røst; (8) troms; (9) hornøy; (10) baffin island (single naumanni individual collected, possible colony present but of unknown subspecies); (11) jan mayen; (12) bjørnøya; (13) novaya zemyla; (14) svalbard (main group of islands). figure based on gaston & jones (1998) and lowther et al. (2020). high-arctic boundary from kurvits et al. (2010). the taxonomic nomenclature of atlantic puffin has varied throughout much of the 20th century, but generally the species includes three subspecies (f. a. grabae, arctica and naumanni), largely differentiated by body size (e.g., bill, wing and mass) and geographic location (for review, see salomonsen 1944; vaurie 1965; harris & wanless 2011). the puffins of the british isles, faroe islands, france, the english channel islands and southern norway are designated f. a. grabae and are the smallest in size, whereas individuals in iceland, northern norway, southern greenland, canada and the us are considered f. a. arctica and are of intermediate size (fig. 1). puffins nesting in high-arctic greenland, svalbard (excluding bjørnøya) and novaya zemlya are distinctly larger than those in the south and are commonly referred to as “large-billed” puffins or the f. a. naumanni subspecies (fig. 1). puffins breeding on the norwegian islands of jan mayen and bjørnøya, the latter the southernmost island in the svalbard archipelago, are generally considered intermediate between arctica and naumanni, and, depending upon the morphological data set used, arguments could be made for their inclusion as either subspecies (schaanning 1933; salomonsen 1944; holgersen 1953; camphuysen 1989). table 1 average adult atlantic puffin body size measurements collected from 2010 to 2015 at dalrymple rock, high-arctic greenland. mass (g) mean ± sd n, range bill length (mm) mean ± sd n, range tarsus length (mm) mean ± sd n, range wing length (mm) mean ± sd n, range male 563 ± 62.1 51.9 ± 2.3 37.8 ± 1.4 185.0 ± 7.7 22, 444–716 22, 47.9–56.1 22, 34.5–40.2 22, 168–198 female 526 ± 51.3 49.4 ± 2.2 36.9 ± 1.2 182.0 ± 6.1 22, 426–611 22, 44.6–53.2 21, 34.6–39.2 23, 170–192 one-way anova, males vs. females f1,42 = 5.49 f1,42 = 13.84 f1,41 = 4.76 f1,43 = 2.09 p = 0.04 p = 0.001 p = 0.04 p = 0.16 sexes combined 545 ± 59.2 50.7 ± 2.6 37.3 ± 1.4 183.5 ± 7.0 44, 426–716 44, 44.6–56.1 43, 34.6–40.2 45, 168–198   table 2 body size measurements for f. a. grabae, arctica and naumanni populations in eastern north america and europe to compare size differences with puffins from high-arctic greenland. sexes have been combined except where indicated by ♂ or ♀ after the location name, indicating that measurements are provided for one sex. measurements were of breeding adults or birds with two or more bill grooves except for data provided by corkhill (1972; obvious immatures excluded), vaurie (1965) and dement’ev et al. (1951; unknown ages), pethon (1967) and underwood (2019; “adults”). location lat. subspeciesa mass (g) mean ± sd, n, range statistical comparison with study populationb bill length (mm)c mean ± sd, n, range statistical comparison with study populationb wing length (mm) mean ± sd, n, range statistical comparison with study populationb source nw greenland, this study 76.5° nau 545 ± 59.2, 44, 426–716 50.7 ± 2.6, 44, 44.6–56.1 183.5 ± 7.0, 45, 168–198 this study skomer is., uk 51.7° gra 385 ± 27.9, 158, 310–488 t48 = 17.40, p < 0.001 no data 158.3 ± 2.0, 158, 146–170 t60 = 19.13 p < 0.001 corkhill 1972 isle of may, uk 56.2° gra 391 ± 32.4, 969, ? t44 = 17.14, p < 0.001 45.5 ± 2.2, 464, ? t49 = 12.84, p < 0.001 161.8 ± 5.6, 1615, 149–176 t45 = 20.61, p < 0.001 harris 1979 machias seal is., canada 44.5° arc 434 ± 36.8, 350, ? t47 = 12.15, p < 0.001 48.4 ± 2.6, 384, ? t53 = 5.56, p < 0.001 162 ± 6.0, 356, ? t52 = 19.71, p < 0.001 lowther et al. 2020 gull is., canada 47.3° arc 432 ± 34.7, 308, ? t47 = 12.36, p < 0.001 47.7 ± 2.2, 261, ? t53 = 7.23, p < 0.001 169.0 ± 4.6, 304, ? t49 = 13.47, p < 0.001 in baillie & jones 2003 gannet is., canada 53.9° arc 468 ± 35.1, 401, ? t46 = 8.47, p < 0.001 49.9 ± 2.5, 261, ? t57 = 1.90, p = 0.063 174.4 ± 13.5, 308, ? t100 = 7.02, p < 0.001 baillie & jones 2003 baer, iceland 65.2° arc no data 48.6 ± 2.1, 13, 44.7–51.8 t23 = 2.99, p = 0.007 168.3 ± 4.5, 13, 159–173 t30 = 9.34, p < 0.001 petersen 1976 røst, norway 67.4° arc 450 ± 33.7, 2381, 340–585 t43 = 10.61, p < 0.001 no data 171.8 ± 4.0, 1950, 158–184 t44 = 11.17, p < 0.001 anker-nilssen et al. 2018 troms, norwayc 69.8° arc no data 47.6 ± 0.6, 11, 44.3–49.9 t52 = 7.18, p < 0.001 173.4 ± 1.2, 12, 165–178 t51 = 9.19, p < 0.001 pethon 1967 hornøy, norwayd 70.4° arc no data 47.3 ± 2.3, ca. 329, ? t52 = 8.25, p < 0.001 177.6 ± 4.3, 325, 164–191 t48 = 5.51, p < 0.001 barrett et al. 1985 and harris & wanless 2011 jan mayen, norway ca. 71.0° arc no data 49.9 ± ?, 7, 47–53.5 175.2 ± ?, 7, 164–181 vaurie 1965 bjørnøya, norway ca. 74.4° arc no data 47.3 ± ?, 6, 44–52 167.5 ± ?, 6, 162–176 vaurie 1965 baffin is., canada♂e 66.9° nau 585, 1 57.3, 1 182, 1 gaston & provencher 2012 novaya zemlya, russiaf ca. 74.5° nau 489 ± ?, 11, 420–579 no data 175.6 ± ?, 14, 162–188 dement’ev et al. 1951 svalbard, norwayd 78.5° nau 584 ± 18.7, 16, ? t57 = -3.87, p < 0.001g 51.0 ± 1.5, 16, ? t46 = −0.55, p = 0.583 185.5 ± 3.2, 16, ? t55 = −1.52, p = 0.134 underwood 2019 svalbard, norway ca. 78.9° nau no data 54.4 ± 2.3, 45, 47–58 t85 = −7.10, p < 0.001g 184.5 ± 5.4, 45, 164–194 t82 = −0.76, p = 0.450 le roi 1911 asubspecies names are abbreviated as grabae—gra, arctica—arc and naumanni— nau. bbonferroni-corrected p value of 0.002 was used to determine the significance. cbill length includes cere. dconfidence intervals converted to standard deviation, equation (ci/3.92)*√n. esingle individual. fmeasurements taken from museum specimens and wing length shrinks with drying (harris 1980). gsvalbard measurement is greater. these subspecies designations have become contentious. bédard (1985) found no support for subspecies designations based on morphology, while moen (1991) came to a similar conclusion on the basis of genetic differentiation using allozymes and morphology. both concluded that the apparent latitudinal increase in body size represented a cline within a single panmictic population (i.e., bergmann’s rule; myrberget 1963), which has also been suggested by others (e.g., pethon 1967; barrett et al. 1985). however, its extremely large body size makes the naumanni subspecies unique from individuals farther south in the species’ geographic distribution. in their seminal book, the puffin, harris & wanless (2011) recommend that the naumanni subspecies should be retained until more comprehensive analyses address the issue of its morphological distinctness. published historical morphology measurements of f. a. naumanni are scarce. data from svalbard and novaya zemlya are limited to ca. 144 and ca. 14 samples, respectively (kolthoff 1903; le roi 1911; salomonsen 1944; dement’ev et al. 1951; vaurie 1965; pethon 1967; de korte 1972; harris 1984). data from high-arctic greenland are even scarcer. the only published morphological records appear to be wing measurements of two males (salomonsen 1935). all of these f. a. naumanni samples were collected over a half a century ago, and some specimens were collected as long ago as the 1860s. the only published morphometric data for contemporary f. a. naumanni samples are from gaston & provencher (2012) and underwood (2019) for a single canadian and 16 svalbard puffins, respectively. the paucity of f. a. naumanni measurements, particularly for contemporary samples and from high-arctic greenland, makes statistical comparisons between populations less informative if not impossible. puffins in greenland are found almost exclusively on the west coast and breed from kitsissut avalliit (60° n) to the high arctic of the avanersuaq district (76.5° n), with an estimated population size of 5000 pairs (boertmann 1994, 2007; boertmann et al. 1996; boertmann et al. 2020). the greenland population is considered near threatened and in decline (boertmann 2007), yet the only annual surveys conducted are from the avanersuaq district (this study), and information from other colonies elsewhere in greenland is generally collected anecdotally (boertmann 1994; boertmann et al. 1996). all of what is currently known concerning puffin morphometrics in greenland was provided by salomonsen (1944, 1950). the most northern population of puffins in the western north atlantic is found within the avanersuaq district in the high arctic of north-west greenland (boertmann et al. 1996). seven colonies are known in the area, ranging in size from a few individuals to approximately 75 pairs (boertmann et al. 1996; burnham & burnham 2010; k. burnham unpubl. data). here, we provide data from seven years of morphometric measurements collected at the second largest breeding colony in the high arctic of north-west greenland. these data are important to determine whether there are differences in body size between puffin colonies within and among subspecies designations. methods adult atlantic puffins were studied from 2010 to 2016 at dalrymple rock (igánaq; 76°28’21.65”n, 70°13’12.40”w; fig. 1), an island in the high arctic and the site of one of the seven known breeding colonies in the avanersuaq district in north-west greenland. the puffin colony has an estimated 15–35 pairs that arrive at the end of may and depart by midto late september (k. burnham unpubl. data). unlike colonies to the south in eastern north america and europe, puffins on dalrymple rock are unable to excavate burrows on the account of near surface permafrost; they nest in rock crevices on cliff faces or under boulders (salomonsen 1950; k. burnham unpubl. data). although no information is known about the breeding chronology of our study colony, we documented, through camera-trapping, a chick fledge on 13 september 2017 (k. burnham unpubl. data). using a combination of dip nets and noose carpets, puffins were captured from 3 july to 10 august. after capturing, puffins were weighed, measured, banded (danish government leg band and colour band) and sampled (feathers and blood), after which all were released unharmed. age was determined using bill grooves, a technique described by harris (1981, 1984), and individuals with at least two bill grooves were considered adults. all puffins were sexed using a standard molecular method described elsewhere (bond et al. 2016), using primers 2550f and 2718r (fridolfsson & ellegren 1999) and dna extracted from either blood or breast feathers using the dneasy blood and tissue kit (qiagen inc.). wing length was measured to the nearest 1 mm using a stopped wing ruler, and the right wing was flattened and straightened prior to measurement following gosler (2004). bill length was measured to the nearest 0.01 mm using digital calipers as the distance from the tip of the bill to the distal edge of the cere. tarsus length was measured to the nearest 0.01 mm using digital calipers following procedures described by gosler (2004) for “minimum tarsus.” mass was measured to the nearest 5 g or 10 g using either a 600 g or 1000 g spring balance, respectively. measurements from initial capture for each puffin were used to calculate mean body size provided in table 1 and for all analysis except when noted otherwise. minitab (version 19.2; minitab llc) was used to conduct statistical analysis. all data were tested for normality, and tests with a p value below 0.05 were considered significant unless otherwise noted. linear regression was used to test for relationships between capture date and mass and for annual changes in mean mass, while paired t-tests were used to test for differences in mass among individuals captured in multiple years. a one-way anova was used to test for morphometric differences between male and female puffins within the focal study colony, and a pearson correlation was used to test for association between variables. two-tailed t-tests and a bonferroni-corrected p value of 0.002 were used for comparisons of data from our study colony and summary data for other puffin colonies that have been reported elsewhere (see table 2), and only measurements with a mean, standard deviation and known sample size were included in the analyses. results twenty-two male and 23 female adult puffins were captured on 61 different occasions between 2010 and 2016 (only recaptures in 2016). capture dates ranged from 3 july to 10 august (x̅ = 22 july, sd ± 9.1). all captured birds had at least two bill grooves; no juveniles or sub-adults were observed or captured. marked individuals were commonly observed coming and going from apparent nests, although no adults were observed returning to the colony with fish in their bills, suggesting that our surveys were conducted primarily during the population’s incubation period. no significant correlation was found between mass and capture date for male and female puffins (p = 0.98, r2 = 0.00, n = 22; p = 0.16, r2 = 0.10, n = 22; respectively) or change in annual mean mass for both males and females (p = 0.27, r2 = 0.00, n = 17; p = 0.85, r2 = 0.06, n = 22; respectively) based on measurements collected between 2010 and 2015. for individuals captured in multiple years (1–5 years between captures), no difference in mass was observed between capture years for either male (paired t-test, t6 = 1.81, p = 0.12, n = 7) or female puffins (paired t-test, t7 = 0.19, p = 0.86, n = 8); however, sample sizes were low. adult male puffins were significantly larger than females. males were an average of 36 g heavier and had 2.5 mm and 0.9 mm longer bill and tarsus lengths, respectively (table 1, fig. 2). male wings averaged 3.0 mm longer than females, but this apparent difference was not statistically significant (table 1). tarsus measurements had the greatest overlap between males and females, 80.7%, followed by wing, mass and bill (73.3%, 61.0% and 46.1%, respectively; fig. 2). minimum wing and tarsus lengths of males were shorter than females by 2.0 mm and 0.1 mm, respectively, but minimum mass and bill lengths were smaller for females by 18 g and 3.3 mm, respectively (table 1, fig. 2). when morphological data for both sexes were combined, strong and significant correlations existed between all pairwise comparisons except wing and tarsus (fig. 3). figure 2 boxplots for mass, bill, wing and tarsus length of atlantic puffins from dalrymple rock, high-arctic greenland. figure 3 correlations between body size measurements for adult male and female atlantic puffins captured from 2010 to 2015 at dalrymple rock, high-arctic greenland. the size of the measured puffins from high-arctic greenland was generally larger than those found at more southern latitudes in both eastern north america and europe. when compared with puffins at colonies in canada (machias seal island, gull island and the gannet islands), puffins from high-arctic greenland were significantly larger for all measurements except bill length at the gannet islands (t57 = 1.90, p = 0.06; see table 2 for individual statistical comparisons and reference). comparisons with puffin colonies in the uk (skomer island and isle of may), iceland (baer) and norway (røst, troms and hornøy) yielded similar results with puffins from high-arctic greenland being significantly larger for all measurements except bill length at baer (t23 = 2.99, p = 0.007; table 2). among f. a. naumanni in the high arctic, comparisons with historical data from svalbard (le roi 1911) showed no difference in wing length (t82 = −0.76, p = 0.45), although svalbard puffins had longer bills (t82 = −7.10, p < 0.001). comparison with contemporary data (underwood 2019) varied slightly, with no observed difference in bill or wing length (t46 = −0.55, p = 0.58; t55 = −1.52, p = 0.13; respectively), yet svalbard puffins were on average 39 g heavier (t57 = −3.87, p < 0.001; table 2). aside from svalbard, there are no data of sufficient sample size from other high-arctic populations that allow for statistical comparison. the range of mass of individual puffins from high-arctic greenland (290 g, 426–716) was greater than any other colony included in this analysis. røst, with a range of 245 g (340–585), was next closest, although their sample size was much greater (n = 44 vs. 2381; table 2, fig. 4). similar patterns of large range were observed for bill length, though to a lesser degree, and only svalbard puffins had an equal range of wing length (table 2, fig. 4). figure 4 measurements for (a) wing length, (b) bill length and (c) mass of atlantic puffins from fratercula a. grabae, arctica and naumanni colonies arranged left to right by subspecies and latitude. symbol indicates the mean, and bars indicate the range. measurements are not available for all locations and have been left blank. see fig. 1 for locations of colonies and table 2 for exact means, ranges and sources of data. svalbard (1) is from le roi (1911), and svalbard (2) is from underwood (2019). the asterisk indicates a single individual. measurements from this study are shaded. discussion adult puffins from our study colony were significantly larger than those occurring outside high-arctic north america and europe. in some instances, the mass of individuals from our study colony was more than double that of individuals from more southern colonies, which agrees with what has been described by salomonsen (1944, 1950), vaurie (1965) and harris & wanless (2011) for the larger high-arctic naumanni subspecies. when compared with limited data from naumanni colonies in novaya zemlya and svalbard, high-arctic greenland puffins were larger in size than those from novaya zemlya, and most comparable in size to those from svalbard. wing lengths of two male specimens from high-arctic greenland described by salomonsen (1935) were 185 mm and 194 mm, well within the range of male puffins found in this study. furthermore, the range of morphological measurements of high-arctic greenland puffins was greater than for any other breeding colony included in our study. throughout their southern breeding range, puffins have been shown to demonstrate a high degree of sexual dimorphism, with males being larger than females (corkhill 1972; friars & diamond 2011; harris & wanless 2011; bond et al. 2016). we found similar results for f. a. naumanni in high-arctic greenland; however, measurements overlapped considerably, and wing length differences were not significant between the sexes (fig. 2). differences in size between f. a. naumanni males and females from svalbard are mixed. historical data from vaurie (1965) showed males (n = 24) had longer bills (1.9 mm) and wings (2.4 mm) than females (n = 24). however, contemporary data from underwood (2019) showed virtually no difference in bill length (females 0.1 mm longer) and only a small difference in mass (males 19 g heavier) between males (n = 10) and females (n = 6), with only wing length showing appreciable differences between the sexes (males 5.3 mm longer). additional study is warranted in the svalbard f. a. naumanni puffin population to determine if the observed pattern persists with a larger sample size. temporal trends of body mass change in puffins are spatially varied across the north atlantic. previous research showed that puffins lose 5–10% of their body mass during their approximate three-month breeding season (harris 1979; barrett et al. 1985). our study showed no change in mass for either sex during the sampling period within the breeding season. neither did we find an annual change in mean mass among either sex over the study period or between capture events for the same individual. barrett et al. (2012) also found no change in body size of adult puffins at two norwegian puffin colonies over an approximate 30-year period, despite a significant decrease in egg volume over the same period. a long-term decline in mass, however, was observed in adult puffins on the isle of may (harris & wanless 2011). change in adult mean mass in high-arctic greenland may be occurring, but our limited sample size and collection period (incubation period only) may prevent us from detecting change. the lack of observations of juveniles and sub-adults at our study colony can be accounted for by the fact that these young individuals typically do not arrive at the breeding colonies until after eggs hatch (harris 1983; harris & wanless 2011). as we did not observe adults returning to the colony with fish, our field seasons had likely concluded prior to eggs hatching. puffins in high-arctic greenland and svalbard appear to have the largest overall body size of any known population in the world. the only other records for puffins of comparable size are for a single puffin collected on baffin island, canada, during the breeding season (table 2, fig. 4), and two puffins collected in the faroe islands in winter, which weighed 720 g and 730 g and were likely migrants (gaston & provencher 2012; anker-nilssen et al. 2018). the wing length of the 730 g puffin on the faroe islands was only 174 mm, relatively short for naumanni (wing length not recorded for other specimens). puffins have been shown to increase their body mass by 20–30% outside the chick rearing period (anker-nilssen et al. 2018). a male puffin caught during our study weighed 716 g, which is to our knowledge the largest mass recorded for this species during the breeding season. while these contemporary measurements add to the body of literature for f. a. naumanni, additional research is warranted to further investigate possible reasons why the study population exhibits such large body size and overall variation compared with other atlantic puffin populations. bergmann’s rule generally states that within a taxonomic clade body size increases at higher latitudes and in cooler climates (bergmann 1847), which has been shown generally to apply among birds (ashton 2002; meiri & dayan 2003). barrett et al. (1985) studied 12 puffin colonies in norway and found strong support for a clinal increase in size based on latitude. similar conclusions were reached by harris & wanless (2011) for wing length in puffin colonies throughout the eastern (n = 31) and western (n = 6) atlantic. other auk species breeding throughout much the same geographic range as puffins in the north atlantic also demonstrated clinal relationships with body size, including thick-billed murre (uria lomvia; gaston & hipfner 2020), little auk (alle alle; wojczulanis-jakubas et al. 2011), razorbill (alca torda; barrett et al. 1997; lavers et al. 2020) and black guillemot (cepphus grille; wojczulanis-jakubas et al. 2011; butler et al. 2020). while these clinal increases in size fit well with bergmann’s rule, the exact driving forces are debated for puffins but may include a combination of ocean and air temperature changes (both at breeding and winter grounds) and food quality variation (e.g., moen 1991; wojczulanis-jakubas et al. 2011). while clinal variation may explain the differences in body size between puffins in high-arctic greenland and populations in southern greenland and south-east canada, few samples also exist from intermediate latitudes in the western north atlantic with which to confirm this trend. in west greenland, the nearest large colony (>100 individuals) to our study area is ca. 525 km south, with about five small colonies (<10 pairs) in-between and the largest breeding colonies ca. 1000 km farther south (boertmann et al. 1996; boertmann & huffeldt 2012). to the west, the nearest colony, on coburg island, canada, is ca. 240 km away (thought to be naummani) and was first documented in 1998 (robards et al. 2000). no morphometric data are available from these colonies. between the coburg island colony and the large colonies in newfoundland, over 2500 km distant, few (<10) small colonies are known or thought to exist (nettleship & evans 1985; gaston & provencher 2012; sabina 2017; ebird 2020; lowther et al. 2020) and no morphometric data are available (fig. 1). the relative geographic isolation of the puffin population in high-arctic greenland (including coburg island) is perhaps best compared to the main group of islands in the svalbard archipelago and to iceland, which are ca. 300 km (bjørnøya) and ca. 450 km (faroe islands) from the next nearest populations, respectively. however, svalbard has an estimated 50 colonies and 10 000 puffin pairs (harris & wanless 2011), and iceland has an estimated 800 colonies and 3–4 million pairs (burfield & van bommel 2004), substantially more than the eight or so colonies and 150–250 pairs (k. burnham, unpubl. data), including coburg island, in all of high-arctic greenland. salomonsen (1935) previously noted the presence of exceptionally small individual puffins, “mutants,” in naumanni colonies in svalbard and novaya zemlya (also see kolthoff 1903; le roi 1911). he suggested they comprised between 5% and 10% of the population and believed these individuals to be naumanni, but “genotypically different” and “primitive” (salomonsen 1935). in our study, two females and two males (ca. 9% of our samples) appear to fit this description (fig. 5). the two females have the smallest recorded wing and bill lengths (and mass for one), while the two males have the smallest wing, bill and mass measurements amongst males. while these small puffins may be genotypically different, it is also plausible that they emigrated from more southern colonies that have small body size. although nest site fidelity of adults is extremely high in puffins, natal dispersal has been shown to be highly variable, and the longest documented juvenile dispersal (ca. 550 km) is similar in distance as from our study area to the nearest large colony to the south (harris 1983; harris & wanless 1991; breton et al. 2006; sandvik et al. 2008). however, as salomonsen (1935) points out, if dispersal is occurring, then why would it only be south to north, as no naumanni-sized individuals have been recorded during the breeding season at more southern colonies. figure 5 measurements of individual atlantic puffins captured at dalrymple rock. circled samples indicate individuals which may meet salomonsen’s (1935) definition of “mutant.” speciation in seabirds has been well studied, and multiple mechanisms have been identified as playing significant roles (e.g., friesen et al. 2007; friesen 2015; lombal et al. 2020). for example, friesen et al. (2007) suggest that genetic structure in migratory seabirds is likely a result of species that have multiple population-specific non-breeding (wintering) areas. this fits well for what is known on other north atlantic auk species, such as thick-billed murre and little auk, which show little genetic differentiation between colonies and which have varying degrees of overlap in wintering areas (fort et al. 2013; wojczulanis-jakubas et al. 2014; tigano et al. 2015; frederiksen et al. 2016). unfortunately, data for puffins are much more limited, and the only genetic analysis carried out to date was between three colonies in iceland and, in the uk, the isle of may and hermaness (moen 1991). results showed no genetic differentiation between colonies in iceland, the isle of may and hermaness, and the wintering area for isle of may puffins partially overlapped with those of icelandic colonies (no data for wintering area of hermaness colony; moen 1991; harris et al. 2010; fayet et al. 2017). while no large-scale genetic analysis of puffin colonies in the north atlantic has been undertaken, fayet et al. (2017) provide data on wintering areas of both north american and european colonies. results showed a high degree of overlap in wintering areas, which would suggest little genetic differentiation may exist between colonies (see friesen et al. 2007). no winter range data have been published for puffins from high-arctic greenland, or any other naumanni population, and it is therefore unknown if their winter range overlaps with those of more southern colonies. conclusion that puffins from high-arctic greenland are morphologically different from (i.e., larger than) those found at more southern latitudes is in no doubt. furthermore, as there are no puffin colonies directly to the south in greenland or to the south-west in canada, it appears the puffin population in high-arctic greenland is also relatively geographically isolated, yet the large variation in morphometric measurements suggests connections with populations to the south. while the reported differences in morphology and the apparent geographic isolation of high-arctic greenland puffins are supportive of the naumanni subspecies, genetic analyses are needed to elucidate whether there is differentiation between puffin populations within and between subspecies. acknowledgements the authors thank bridger konkel, calen offield, julie konkel, fallon meyer, sarah baugh and claire behnke for assistance in the field. logistics help was provided by polar field services and jessy jenkins and kim derry, the idaho bureau of land management and virginia hoffman, the united states air force, the 109th air national guard and the national science foundation. permits were provided by the greenland home rule government. special thanks go to the residents of thule air base for their assistance in supporting our research. two anonymous reviewers provided helpful comments that improved this article. all applicable ethical guidelines for the use of birds in research have been followed, including those presented in the ornithological council’s guidelines to the use of wild birds in research (fair et al. 2010). references anker-nilssen t., jens-kjeld j. & harris m.p. 2018. fit is fat: winter body mass of atlantic puffins fratercula arctica. bird study 65, 451–457,doi: 10.1080/00063657.2018.1524452. ashton k.g. 2002. patterns of within-species body size variation of birds: strong evidence for bergmann’s rule. global ecology & biogeography 11, 505–523, doi: 10.1046/j.1466-822x.2002.00313.x. baillie s.m. & jones i.l. 2003. atlantic puffin (fratercula arctica) chick diet and reproductive performance at colonies with high and low capelin (mallotus villosus) abundance. canadian journal of zoology 81, 1598–1607, doi: 10.1139/z03-145. barrett r.t., anker-nilssen t. & krasnov y.v. 1997. can norwegian and russian razorbills alca torda be identified by their measurements? marine ornithology 25, 5–8. barrett r.t., fieler r., anker-nilssen t. & rikardsen f. 1985. measurements and weight changes of norwegian adult puffins fratercula arctica and kittiwakes rissa tridactyla during the breeding season. ringing & migration 6, 102–112, doi: 10.1080/03078698.1985.9673865. barrett r.t., nilsen e.b. & anker-nilssen t. 2012. long-term decline in eggs size of atlantic puffins fratercula arctica is related to changes in forage fish stocks and climate conditions. marine ecology progress series 457, 1–10, doi: 10.3354/meps09813. bédard j. 1985. evolution and characteristics of the atlantic alcidae. in d.n. nettleship & t.r. birkhead (eds.): the atlantic alcidae. pp. 1–51. london: academic press. berglund p.a. & hentati-sundberg j. 2015. arctic seabirds breeding in the african-eurasion waterbird agreement (aewa) area: status and trends 2014. caff assessment series report 13. akureyri, iceland: conservation of arctic flora and fauna international secretariat. bergmann c. 1847. ueber die verhältnisse der wärmeökonomie der thiere zu ihrer grösse. (on the relationship between the thermal economy of animals and their size.) gottinger studien 3, 595–708. birdlife international 2020. species factsheet: fratercula arctica. accessed on the internet at http://www.birdlife.org on 24 march 2020. boertmann d. 1994. an annotated checklist to the birds of greenland. monographs on greenland, bioscience 38. copenhagen: university of copenhagen. boertmann d. 2007. greenland’s red list. aarhus, denmark: national environmental research institute, dept. of arctic environment, aarhus university. boertmann d. & huffeldt n.p. 2012. seabird colonies in the melville bay, northwest greenland. scientific report from dce—danish centre for environment and energy 45. aarhus, denmark: danish centre for environment and energy, aarhus university. boertmann d., merkel f. & gilg o. 2020. seabird breeding colonies in east and north greenland: a baseline. arctic 73, 20–39, doi: 10.14430/arctic69885. boertmann d.a., mosbech a., falk k. & kampp k. 1996. seabird colonies in western greenland (60°–79°30´ n. lat). neri technical report 170. copenhagen: national environmental research institute. bond a.l., standen r.a., diamond a.w. & hobson k.a. 2016. sexual size dimorphism and discriminant functions for predicting the sex of atlantic puffin (fratercula arctica). journal of ornithology 157, 875–883, doi: 10.1007/s10336-016-1332-8. breton a.r., diamond a.w. & kress s.w. 2006. encounter, survival, and movement probabilities from an atlantic puffin (fratercula arctica) metapopulation. ecological monographs 76, 133–149, doi: 10.1890/05-0704. burfield i. & van bommel f. 2004. birds in europe (population estimates, trends, and conservation status). cambridge, uk: birdlife international. burnham j.l. & burnham k.k. 2010. an ornithological survey of the carey islands, northwest greenland. dansk ornitologisk forenings tidsskrift 104, 26–37. butler r.g., buckley d.e., nettleship d.n., boesman p.f.d. & garcia e.f.j. 2020. black guillemot (cepphus grylle), version 1.0. in s.m. billerman (ed.): birds of the world. ithaca, ny: cornell lab of ornithology. accessed on the internet at https://doi.org/10.2173/bow.blkgui.01 on 4 oct 2020. camphuysen c.j. 1989. biometrics of auks at jan mayen. seabird 12, 7–10. corkhill p. 1972. measurements of puffins as criteria of sex and age. bird study 19, 193–201, doi: 10.1080/00063657209476343. de korte j. 1972. birds, observed and collected by “de nederlandse spitsbergen expeditie” in west and east spitsbergen, 1967 and 1968–’69; third and last part. beaufortia 261, 23–58. dement’ev g.p., meklenburtsev r.n., sudilovskaya a.m. & spangerberg e.p. (eds.) 1951. birds of the soviet union. jerusalem: israel program for scientific translations. ebird 2020. an online database of bird distribution and abundance. (web application.) ithaca, ny: cornell lab of ornithology. accessed in the internet at http://www.ebird.org on 7 october 2020. fair j.m., paul e. & jones j. (eds.) 2010. guidelines to the use of wild birds in research. 3rd edn. washington, dc: ornithological council. fayet a.l., freeman r., anker-nilssen t., diamond a., erikstad k.e., fifield d., fitzsimmons m.g., hansen e.s., harris m.p., jessop m., kouwenberg a., kress s., mowat s., perrins c.m., petersen a., petersen i.k., reiertsen t.k., robertson g.j., shannon p., sigurðsson i.a., shoji a., wanless s. & guilford t. 2017. ocean-wide drivers of migration strategies and their influence on population breeding performance in a declining seabird. current biology 27, 3871–3878, doi: 10.1016/j.cub.2017.11.009. fort j., moe b., strøm h., grémillet d., welcker j., schultner j., jerstad k., johansen k.l., phillips r.a. & mosbech a. 2013. multicolony tracking reveals potential threats to little auks wintering in the north atlantic from marine pollution and shrinking sea ice cover. diversity and distributions 19, 1322–1332, doi: 10.1111/ddi.12105. frederiksen m., descamps s., erikstad k.e., gaston a.j., gilchrist h.g., grémillet d., johansen k.l., kolbeinsson y., linnebjerg j.f., mallory m.l., tranquilla l.a.m., merkel f.r., montevecchi w.a., mosbech a., reiertsen t.k., robertson g.j., steen h., strøm h. & thørarinsson t.l. 2016. migration and wintering of a declining seabird, the thick-billed murre uria lomvia, on an ocean basin scale: conservation implications. biological conservation 200, 26–35, doi: 10.1016/j.biocon.2016.05.011. friars k.a. & diamond a.w. 2011. predicting the sex of atlantic puffins, fratercula arctica, by discriminant analysis. waterbirds 34, 304–311, doi: 10.1675/063.034.0305. fridolfsson a.-k. & ellegren h. 1999. a simple and universal method for molecular sexing of non-ratite birds. journal of avian biology 30, 116–121, doi: 10.2307/3677252. friesen v.l. 2015. speciation in seabirds: why are there so many species … and why aren’t there more? journal of ornithology 156, 27–39, doi: 10.1007/s10336-015-1235-0. friesen v.l., burg t.m. & mccoy k.d. 2007. mechanisms of population differentiation in seabirds. molecular ecology 16, 1765–1785, doi: 10.1111/j.1365-294x.2006.03197.x. gosler a.j. 2004. birds in the hand. in w.j. sutherland et al. (eds.): bird ecology and conservation: a handbook of techniques. pp. 85–118. oxford: oxford university press. gaston a.j. & jones i.l. 1998. the auks. oxford: oxford university press. gaston a.j. & pipfner j.m. 2020. thick-billed murre (uria lomvia), version 1.0. in s.m. billerman (ed.): birds of the world. ithaca, ny: cornell lab of ornithology. accessed on the internet at https://doi.org/10.2173/bow.thbmur.01 on 4 oct 2020. gaston a.j. & provencher j. 2012. a specimen of the high arctic subspecies of atlantic puffin, fratercula arctica naumanni, in canada. canadian field naturalist 126, 50–54, doi: 10.22621/cfn.v126i1.1297. hansen e.s. & garðarsson a. 2009. the atlantic puffin population size of the westman islands, iceland. in e. stienen et al. (eds.): seabird group. 10th international conference. book of abstracts. brugge, belgium. 27–30 march 2009. vliz special publication 42. communications of the research institute for nature and forest – inbo.m.2009.1. p. 30. brussels and oostende: belgium research institute for nature and forest / flanders marine institute (vliz). harris m.p. 1979. measurements and weights of british puffins. bird study 26, 179–186, doi: 10.1080/00063657909476636. harris m.p. 1980. post-mortem shrinkage of wing and bill of puffins. ringing and migration 3, 60–61, doi: 10.1080/03078698.1980.9673765. harris m.p. 1981. age determination and first breeding of british puffins. british birds 74, 246–256. harris m.p. 1983. biology and survival of the immature puffin fratercula arctica. ibis 125, 56–73, doi: 10.1111/j.1474-919x.1983.tb03083.x. harris m.p. 1984. the puffin. london: t & ad poyser. harris m.p., daunt f., newell m., phillips r.a. & wanless s. 2010. wintering areas of adult atlantic puffins fratercula arctica from a north sea colony as revealed by geolocation technology. marine biology 157, 827–836, doi: 10.1007/s00227-009-365-0. harris m.p. & wanless s. 1991. population studies and conservation of puffins fratercula arctica. in c.m. perrins et al. (eds): bird population studies. pp. 230–248. oxford: oxford university press. harris m.p. & wanless s. 2011. the puffin. london: t & ad poyser. holgersen h. 1953. on a collection of birds from jan mayen. astarte 5, 1–9. kolthoff g. 1903. bidrag till kännedom om norra polartrakternas däggdjur och fåglar. (contribution to knowledge about the mammals and birds of the arctic.) kungliga svenska betenskaps-akademiens handlingar 36(9). stockholm: p.a. norstedt & söner. kurvits t., alfthan b. & mork e. (eds). 2010. arctic biodiversity trends 2010—selected indicators of change. akureyri, iceland: conservation of arctic flora and fauna international secretariat. lavers j., hipfner j.m. & chapdelaine g. 2020. razorbill (alca torda), version 1.0. in s.m. billerman (ed.): birds of the world. ithaca, ny: cornell lab of ornithology. accessed on the internet at https://doi.org/10.2173/bow.razorb.01 on 4 oct 2020. le roi o. 1911. die avifauna der bären-insel und des spitzbergen-archipels. (the avifauna of bjørnøya and the spitsbergen archipelago.) in a. koenig (ed.): avifauna spitzbergensis. (avifaua of spitsbergen.) pp. 113–294. berlin: w. junk. lombal a.j., o’dwyer j.e., friesen v., woehler e.j. & burridge c.p. 2020. identifying mechanisms of genetic differentiation among populations in vagile species: historical factors dominate genetic differentiation in seabirds. biological reviews 95, 625–651, doi: 10.1111/brv.12580. lowther p.e., diamond a.w., kress s.w., robertson g.j., russell k., nettleship d.n., kirwan g.m., christie d.a., sharpe c.j., garcia e.f.j. & boesman p.f.d. 2020. atlantic puffin (fratercula arctica), version 1.0. in s.m. billerman (ed): birds of the world. ithaca, ny: cornell lab of ornithology. accessed on the internet at https://doi.org/10.2173/bow.atlpuf.01 on 4 oct 2020. meiri s. & dayan t. 2003. on the validity of bergmann’s rule. journal of biogeography 30, 331–351, doi: 10.1046/j.1365-2699.2003.00837.x. moen s.m. 1991. morphological and genetic variation among breeding colonies of the atlantic puffin (fratercula arctica). auk 108, 755–763, doi: 10.1093/auk/108.4.755. myrberget s. 1963. systematic position of fratercula arctica from a north norwegian colony. norwegian journal of zoology 11, 74–84. nettleship d.a. & evans p.g.h. 1985. distribution and status of the atlantic alcidae. in d.n. nettleship & t.r. birkhead (eds.): the atlantic alcidae. pp. 54–149. london: academic press. petersen a. 1976. size variables in puffins fratercula arctica from iceland, and bill features as criteria of age. ornis scandinavica 7, 185–192, doi: 10.2307/3676188. pethon p. 1967. the systematic position of the norwegian common murre uria aalge and puffin fratercula arctica. meddelelser fra det zoologiske museum, oslo 80, 84–95. robards m., gilchrist h.g. & allard k. 2000. breeding atlantic puffins, fratercula arctica, and other bird species of coburg island, nunavut. canadian field naturalist 114, 72–77. salomonsen f. 1935. aves. in s.l. tuxen et al. (eds.): the zoology of the faroes. vol. 3. part 2. copenhagen: a.f. høst & søn. salomonsen f. 1944. the atlantic alcidae. göteborg: wettergren & kerber. salomonsen f. 1950. grønlands fugle. (birds of greenland.) copenhagen: munksgaard. sabina w. 2017. cws: waterbird colony database (atlantic region). version 1. in obis canada digital collections. bedford institute of oceanography, dartmouth, ns, canada. accessed on the internet at https://doi.org/10.15468/vlrjfx accessed via gbif.org on 2020-05-04 on 4 may 2020. sandvik h., erikstad k.e., fauchald p. & tverra t. 2008. high survival of immatures in a long-lived seabird: insights from a long-term study of the atlantic puffin (fratercula arctica). auk 125, 423–730, doi: 10.1525/auk.2008.07059. schaanning h.t.l. 1933. zoological results of the norwegian scientific expedition to east-greenland i: a contribution to the bird fauna of jan mayen. skrifter om svalbard og ishavet 49, 25–39. tigano, a., damus m, birt t.p., morris-pocock j.a., artukhin y.b. & friesen v.l. 2015. the arctic: glacial refugium or area of secondary contact? inference from the population genetic structure of the thick-billed murre (uria lomvia), with implication for management. journal of heredity 106, 238–246, doi: 10.1093/jhered/esv016. underwood a.k.p. 2019. toxicology of the svalbard atlantic puffin. master’s thesis, uit the arctic university of norway, tromsø, norway. vaurie c. 1965. the birds of the palearctic fauna: non-passeriformes. london: h.f. & g. witherby limited. wojczulanis-jakubas k., jakubas d., welcker j., harding a.m.a., karnovsky n.j., kidawa d., steen h., stempniewics l. & camphuysen c.j. 2011. body size variation of a high-arctic seabird: the dovekie (alle alle). polar biology 34, 847–854, doi: 10.1007/s00300-010-0941-6. wojczulanis-jakubas k., kilikowska a., harding a.m.a., jakubas d., karnovsky n.j., steen h., strøm h., welcker j., gavrilo m., lifjeld j.t. & johnsen a. 2014. weak population genetic differentiation in the most numerous arctic seabird, the little auk. polar biology 37, 621–630, doi: 10.1007/s00300-014-1462-5. blake.indd 123blake 2006: polar research 25(2), 123–137 occurrence of the mytilus edulis complex on nordaustlandet, svalbard: radiocarbon ages and climatic implications weston blake, jr. fragments of the blue mussel (mytilus edulis complex) are present on raised beaches in the vicinity of langgrunnodden and kinnvika, northwestern nordaustlandet, svalbard. both of these localities are north of 80° n. new radiocarbon age determinations, together with earlier results, show that mytilus colonies were present in this area for much of the fi rst half of holocene time—from approximately 9000 to 5800 14c yr bp. mytilus has also been recorded farther south in nordaustlandet, at three localities in wahlenbergfjorden. age determinations of shells at two of these sites have yielded results in the range of 7400 to 6900 14c yr bp. the arrival of mytilus to nordaustlandet coincided with the early holocene infl ux of warm north atlantic water off the west coast of spitsbergen. the drastic warming in early holocene time, which resulted in the rapid melt-off of glaciers and ice caps in svalbard, also facilitated the establishment and perserverance of mytilus colonies at this high latitude. w. blake, jr., geological survey of canada, 615 booth st., ottawa, ontario k1a 0e9, canada, weblake@nrcan.gc.ca. the common blue mussel (mytilus edulis) has featured in arctic scientifi c literature for well over a century. among the discoveries of the 1861 swedish expedition to spitsbergen, for example, were fragments of m. edulis at the westernmost point of nordaustlandet (figs. 1, 2), a locality then known as shoal point, now called lang grunnodden (chydenius 1865). until recently the arctic occurrences of this wide-ranging species have been referred to m. edulis l., but feder et al. (2003) have shown that specimens collected alive at barrow, on the northern coast of alaska, are m. trossulus on the basis of dna analysis (see also norton & feder 2006). for the purposes of the present paper, and following feder et al. (2003), the m. edulis complex will be taken to include both species, should m. trossulus turn out to be present in svalbard also. equally important as the species assignment, in terms of the discussion here, is the fact that mytilus has long been regarded as an indicator of somewhat warmer sea conditions than those which have obtained throughout the past two centuries in svalbard (nathorst 1901a; hoel 1909; högbom 1911, 1913; elton & baden-powell 1931; feyling-hanssen & jørstad 1950; feyling-hanssen 1955 [includes a detailed discussion and many references]; feyling-hanssen & olsson 1960; funder 1992; hjort et al. 1992; salvigsen et al. 1992; hjort et al. 1995; salvigsen 2002, 2005; salvigsen & høgvard 2005), in greenland (nathorst 1901b; noe-nygaard 1932; hjort & funder 1974; funder 1978, 1990; kelly 1985; funder & fredskild 1989; funder & weidick 1991) and elsewhere in the high arctic, such as on coburg island in the northern tier of the islands of the 124 mytilis edulis on nordaustlandet, svalbard canadian arctic archipelago (blake 1973). although m. edulis has occasionally been found alive on materials that have drifted to svalbard waters with the west spitsbergen current (heintz 1926; christiansen 1965; salvigsen 2002, 2005), until recently it has not been found living there. now mytilus has been reported from both bjørnøya (węsławski et al. 1997; although berge et al. [2006] emphasize that the few individuals found there do not constitute a population) and from a group of skerries in outer isf jord en, spitsbergen (berge et al. 2005). in the latter locality its appearance is attributed to the “unusually high northward mass transport of warm atlantic water resulting in elevated sea-surface temperatures in the north atlantic and along the west coast of svalbard” (berge et al. 2005: 167). the colony at this site has been shown to be m. edulis on the basis of dna analysis (berge et al. 2006). it is interesting to note that mytilus was not recorded in 1908 in the same general area by odhner (1915), despite an extensive programme of dredging, and berge et al. (2006) also observe that numerous surveys along the western coast of spitsbergen over the last 30 years have failed to reveal the presence of mytilus. however, feder et al., as a result of extensive work along the northern and north-western coasts of alaska, reached a very different conclusion with regard to the value of mytilus as an indicator of warmer sea conditions: “...water temperature cannot be the primary determinant of mytilus persistence in the 20° 80° 80° 24°18° sjuoyane phippsoya søre repøya nordaustlandet spitsbergen kong karls land edgeøya storøya 100 100 1 0 0 1 0 0 100 10 0 10 0 100 10 0 20 0 200 1 0 0 1 0 0 200 20 0 40 0 60 0 100 200 2 0 0 200 200 lågøya wargentinflya søre russoya nordre russøya sveanor brageneset idunneset gyldénøyane v aigattoyane rijpdalen r ijp fjo rd e n d u ve fjo rd e n s ab in eb uk ta li nd ha ge nb uk ta zorgdragerfjorde n arkvatnet g le nh al vø ya f in n m al m gr en fjo rde n is fjo rd en dalvågen brennevinsfjorde n l a d y f ra n klin fjorden murchisonfjorden kinnvika d etterbukta l a n g g ru n n odden h in lo p e n re n n a wa hlen berg fjorde n l o m fjo rd e n h i n l o p e n s t r e t e t bodleybreen brånevatnet etonbreen n o r d a u s t l a n d e t a u s t f o n n a v e s t f o n n a krystallvatnet søre franklinbreen p r in s o s c a r s l a n d is isp yn te n svartkn ausflya bråsvellbreen glacier ice moraine sites with 14c data sites with dated mytilus contour interval, 200 m depth contour, 100 m 25 km fig. 1. location map of nordaustlandet, svalbard, showing sites mentioned in the text. illustration based on a 1:1 000 000 map of svalbard by kristiansen & sollid (1986). bjørnøya, at 74° 30 'n & 19° e, is ca. 225 km sse of the southern tip of spitsbergen. 125blake 2006: polar research 25(2), 123–137 arctic. low water temperature is known to prolong dispersive life-cycle stages and to slow later development and growth, but it has not been shown to limit mytilus survival or reproduction. we suggest that the presence of this bivalve during periods of higher sea level during the early holocene is a response to lower and more variable salinity of coastal waters rather than to increased temperature” (2003: 402). thirteen radiocarbon age determinations of m. edulis in raised beaches are now available from nordaustlandet, the northernmost of the main islands in the svalbard archipelago. all except two of these determinations are based on collections made by the writer north of the 80th parallel, and nine of the 13 age determinations are based on single valves or single shell fragments, thus eliminating the chance of mixing shell material of different ages. these occurrences are the most northerly known in which m. edulis is found in abundance on raised beaches. it thus seems appropriate to discuss the signifi cance of these fi nds in light of the hypothesis advanced by feder et al. (2003) and the 2004 discovery of a colony of living m. edulis near the entrance to isfjorden, spitsbergen (berge et al. 2005; berge et al. 2006), some 230 km to the south-west of langgrun nodden. materials and methods collections and radiocarbon ages of mytilus shells from nordaustlandet following the 1861 discovery of m. edulis at langgrunnodden, when numerous shells were collected by a. j. malmgren at about 9 to 15 m a.s.l. in clay (hägg 1950), the second fi nd of this species in nordaustlandet was made by k. s. sandford, geologist on the 1924 oxford university expedition. he reported rare valves of the blue mussel in boulder clay at ca. 55 m a.s.l. at a site along the northern shore of inner wahlenbergfjorden (fig. 1 and sandford 1929). until recently the shells in this collection had not been dated, but the elevation reported is some 40 m higher than any of the previously dated holocene collections of mytilus from nordaustlandet (table 1). thus, it seemed reasonable to surmise that sandford’s collection might represent pre-last glaciation material, possibly transported upward by a southward advancing bodleybreen, or possibly moved by an enlarged etonbreen fl owing westward out the fjord. both glaciers have a history of surging (dowdeswell 1986a, 1986b; lefauconnier & hagen 1991). pelecypod shells of several other species which predate the last glaciation have been collected at numerous sites around nordaustlandet and on sjuøyane to the north (blake 1961a, 1962, 1981, 1989, 1995; olsson & fig. 2. oblique aerial view north-west across murchisonfjorden, showing the principal areas where mytilus has been collected: kinnvika and langgrunnodden. this image is a portion of photograph s38-1247 taken by b. luncke, 28 july 1938; between 0540 and 0615 hours. (photograph courtesy of the norwegian polar institute.) 126 mytilis edulis on nordaustlandet, svalbard blake 1962; salvigsen & nydal 1981; forman & ingólfsson 2000). also, pre-holocene mytilus shells have been reported from one of the inner branches of isfjorden, spitsbergen (mangerud & svendsen 1992a, 1992b). however, the single robust valve dated from sandford’s collection turned out to be holocene, the lab-reported age being 7370 ± 20 14c yr bp (lab. no. uciams-21868), or 6930 ± 20 14c yr bp after the reservoir effect is taken into account (table 1, fig. 3). because of its elevation, well above early holocene shells collected by the writer at ca. 43 m a.s.l. (table 2), it seems likely that both shells and the enclosing ‘boulder clay’ do indeed represent glacier-transported material, from a late holocene readvance of bodleybreen. table 1. radiocarbon ages on shells of the mytilus edulis complex, nordaustlandet, svalbard. field no. a elev. (m) weight used (g) lab. no. b age, reported by lab. age, corrected for apparent age of seawater c δ13c (pdb) ‰ comments langgrunnodden/detterbukta wb-58-303 ∼14.0 0.16 uciams-19833 9470 ± 25 9030 ± 25 0.1 ± 0.1 single fragment. wb-58-303 ∼14.0 0.27 uciams-21867 9490 ± 20 9050 ± 20 –0.65 ± 0.1 single fragment. wb-58-312 wb-58-312 9.0 9.0 } 90.0 u-173{ u-174 9200 ± 190 8530 ± 190 8760 ± 190 8090 ± 190 –2.0 –1.0 numerous fragments—innermost 13 % of shell material. next 14 % of shell material. outermost 73 % removed by hcl leach. wb-58-312 9.0 0.23 uciams-20526 8790 ± 15 8350 ± 15 –0.4 ± 0.1 single fragment. kinnvika, murchisonfjorden wb-90-28 14.5 0.23 ua-2102 9060 ± 90 8620 ± 90 — single fragment of blue-violet shell only. wb-90-28 14.5 0.16 uciams-20527 8960 ± 20 8520 ± 20 0.6 ± 0.1 single fragment of blue shell. wb-66-178 7.5 — gak-1916 d 7530 ± 130 7530 ± 130 — numerous fragments. wb-66-178 7.5 0.76 uciams-16174 7095 ± 20 6655 ± 20 –0.27 ± 0.1 single fragment. wb-90-25 5.1 0.14 ua-11158 6435 ± 105 5995 ± 105 0.5 single fragment. inner fraction dated. wb-90-25 5.1 0.11 uciams-19834 6335 ± 25 5895 ± 25 0.2 ± 0.1 single fragment. wahlenbergfjorden sa-97-100 ∼10 5.0 t-13426 7260 ± 105 7260 ± 105 e — 1 whole valve plus several large fragments, all of good quality. coll. a. m. tebenkov. oum qx. 1639 ∼55 0.40 uciams-21868 7370 ± 20 6930 ± 20 –0.74 ± 0.1 single left valve, 6 cm long, 2.5 cm high, shell 2 3 mm thick; periostracum partly intact. coll. k. s. sandford. a all samples with fi eld designation wb were collected by w. blake, jr.; r. bergström helped make the 1958 collections. b laboratory designations: u = uppsala; ua = tandem accelerator laboratory, uppsala; uciams = university of california, irvine (ams); gak = gakushuin university, japan; t = trondheim. c following mangerud & gulliksen (1975) a reservoir effect of –440 years is applied to samples with designations uciams, u and ua. d doubts about the accuracy of some gakushuin 14c ages have been expressed earlier (blake 1980, 1989); the gakushuin determination on marine shells is corrected to δ13c = 0.0 ‰, so no additional correction is applied (kigoshi et al. 1962). e as reported by salvigsen (2002) with a built-in correction of –440 years. 127blake 2006: polar research 25(2), 123–137 following sandford’s fi nd in wahlenbergfjorden the next discovery of m. edulis in nordaustlandet was made in 1931, from two sites on the southern side of murchisonfjorden (figs. 1, 2): at 14.5 m a.s.l. near sveanor, the base of the swedish–norwegian arctic expedition, and on nearby søre russøya, where occasional shells were found in the raised beaches at an approximate elevation of 16 to 19 m (kulling 1936). although several later visits have been made to these general locations, unfortunately no additional fi nds of mytilus have been recorded. next, j. j. donner and r. g. west, members of the 1955 oxford university expedition, collected two valves of m. edulis at 4.5 m a.s.l. near the top of a disturbed section at idunneset, on the north side of wahlenbergfjorden, near the mouth of the fjord (donner & west 1957). these shells have not been dated. mytilus edulis shells were not found on the nearby gyldénøyane at the mouth of wahlenbergfjorden (elton & baden-powell 1931), nor were any discovered in the vicinity of the 1955 expedition’s base, brage neset, at the northern entrance to the fjord (donner & west 1957, 1995). more recently, in 1997, a. m. tebenkov collected m. edulis shells at brånevatnet in innermost wahlenbergfjorden (actually east of the present-day head of the fjord) at ca. 10 m a.s.l., and these shells yielded an age of 7260 ± 105 14c yr bp (t-13426; salvigsen 2002). so far wahlenbergfjorden is the only fjord-head locality in nordaustlandet where mytilus has been collected. its occurrence there is not surprising, however, in view of the more favourable environments characteristic of fjord-head localities in svalbard (summerhayes & elton 1928), coupled with the southward set of the current with the falling tide in hinlopenstretet (binney 1926; mosby 1938; ślubowska et al. 2005). in particular, the area north of etonbreen in innermost wahlenbergfjorden is known to have the richest terrestrial fl ora in nordaustlandet (neilson 1968). in 1958 abundant fragments of mytilus shells were discovered by the writer and r. bergström, members of the swedish glaciological expedition to nordaustlandet, on the ground surface (in raised beach gravels and sorted circles) inland from detterbukta and north-east of langgrunnodden, the westernmost point of nordaustlandet. this is the same site that had been visited by the 1861 swedish expedition. one collection was dated at the then newly-opened laboratory in uppsala. following a fairly heavy hcl leach to remove any surface contamination such as secondary calcite crusts, these shells (the innermost 13 % of shell material) yielded a lab-reported age of 9200 ± 190 14c years (u-173; table 1). this is the age converted to the nbs oxalic acid standard—the original published laboratory age of 9070 ± 190 14c yr bp was based on the swedish elm standard (olsson 1960; olsson et al. 1961; i. u. olsson, pers. comm. 1961, 1966). the 9070 ± 190 14c yr bp value also was used in the original papers dealing with postglacial emergence (blake 1961a, 1962; olsson & blake 1962), and it is often cited in the literature (e.g. salvigsen et al. 1992; salvigsen 2002), but the 9200 year-value is the correct one that should be used for the lab-reported age in radiocarbon years (see also deevey et al. 1967). the next 14 % of shell material yielded a lab-reported age of 8530 ± 190 (u-174). the age difference between u-173 and u-174 suggests that this large sample (90 g), collected over a signifi cant area of beaches, was made up of shells of varying age and varying thickness, hence the discrepancy between the two dated fractions. with the advent of radiocarbon dating by means of accelerator mass spectrometry (ams) in the fig. 3. inner left valve of mytilus edulis from the north side of wahlenbergfjorden, following sampling for 14c age determination. scale is 1 cm in length. collected 1924 by k. s. sandford, oxford university expedition. identifi ed by d. f. w. baden-powell (oum qx 1639). (photograph by w. blake, jr., 26 march 2006.) 128 mytilis edulis on nordaustlandet, svalbard late 1970s, several age determinations have been made on individual fragments of mytilus, collected by the writer in 1966 on the stockholm university svalbard expedition and in 1990 on the nordaustlandet-90 expedition. these shells came from the raised beaches in the vicinity of kinnvika, at the northern entrance to murchison fjorden (figs. 2, 4). they range in age from 8620 ± 90 14c yr bp (ua-2102; cf. blake 1995, where the labreported age of 9060 ± 90 was used) to 5895 ± 25 14c yr bp (uciams-19834; table 1). in addition, new analyses of the original collections from the vicinity of langgrunnodden have been made and these results are reported here as well. as mentioned earlier in this section, and following the approach taken by several others in reporting radiocarbon age determinations from svalbard (salvigsen et al. 1992; hjort et al. 1992; hjort et al. 1995; koç et al. 2002; salvigsen 2002; salvigsen & høgvard 2005; ślubowska et al. 2005; all of whom cite mangerud & gulliksen 1975), a reservoir effect of –440 years to compensate for the apparent age of seawater has been applied to the 14c ages in tables 1 and 2 (see footnotes to tables). this value corresponds closely to the 410year difference if radiocarbon ages on shells are corrected to a δ13c value of 0.0 ‰, which was the practice at the geological survey of canada at the time that shells from nordaustlandet were dated (table 2; see lowdon 1985; blake 1987). in addition, it is also worth noting that a single intact buccinum glaciale shell, collected in 1958 amidst the debris of an abandoned russian trapping hut on nordre russøya, murchisonfjorden (blake 1961b), yielded an age of 295 ± 70 years (u-122; olsson 1960). when converted to the nbs oxalic acid standard this age becomes 420 ± 80 14c years (i. u. olsson pers. comm. 1966), also close to the 440-year value cited above. however, forman & polyak (1997), in a sophisticated analysis of prebomb molluscs from the kola peninsula, franz josef land and novaya zemlya, derived reservoir ages for franz josef land of only 159 ± 50 (gx-19024) and 263 ± 48 years (gx-19026), so the radiocarbon ages from nordaustlandet eventually may have to be adjusted as well. deglaciation chronology at kinnvika the oldest radiocarbon dated holocene material is a partial shaft of the left humerus of a polar bear (ursus maritimus) collected at 72 m a.s.l. and dated at 10 030 ± 110 14c yr bp (ua-2207). next oldest, and from the raised beaches proper, a partial right pelvic bone from a bearded seal (erignathus barbatus) (both identifi ed by c. r. harington, canadian museum of nature, ottawa, pers. comm. 1990) at 62 m a.s.l. is 9930 ± 100 14c yr bp (ua-2099; both in blake 1996). applying the same marine correction of –440 years (see olsson 1980) to these bones yields ages of 9590 ± 110 and 9490 ± 100 14c yr bp for bear and seal, respectively (table 2). on the opposite, south side of murchisonfjorden, mya truncata shells at 82 m have yielded lab-reported ages of 11 180 ± 190 14c yr bp (u-2095) and 11 150 ± 110 14c yr bp (u-660; both in olsson et al. 1969; blake 1981; hoppe 1987), but note that karlén (1994) places the highest marine limit in this area at 67 m a.s.l. these results become 10 740 ± 190 and 10 710 ± 110, respectively, when the –440 year correction is applied. also, a driftwood log (larix sp.) at 36.5 m elevation near sveanor (kulling 1936), in the vicinity, has provided age determinations from two laboratories: 9400 ± 140 (u-70; converted to the nbs oxalic acid standard; olsson 1959; deevey et al. 1967) and 9420 ± 100 (gsc-3490; blake 1987). these results from wood reinforce the 14c ages of bones and shells as well as the age of the basal organic sediments in krystallvatnet, 10 000 ± 600 14c yr bp (u-92; converted to the nbs oxalic acid standard), some 8 km to the east–north-east of sveanor (olsson 1960; häggblom 1963). individuals of the mytilus edulis complex thus appeared some 900 to 1000 14c years after the earliest mammals were recorded at kinnvika or, assuming that the early ages of shells are correct, roughly 2000 14c years after the sea fi rst entered murchisonfjorden some 10 km to the south of kinnvika. ages between 9500 and 9000 14c years bp on marine pelecypod shells are recorded for the initial incursion of the sea into the heads of nearby fjords such as wahlenbergfjorden and lady frank lin fjorden, slightly earlier at dalvågen (where chlamys islandica and balanus balanus were dated as well as hiatella arctica) near the northern tip of nordaustlandet (table 2; also blake 1987, 1989). elsewhere on nordaustlandet, driftwood at 22 m a.s.l. near the northern tip of prins oscars land dates from 9465 ± 120 14c yr bp (st-7989; karlén 1987), and mya truncata shells from a river section south of the head of rijpfjorden are 9100 ± 140 14c yr bp (gsc-2669; blake 1981, 1987). further east, the earliest radiocarbon age for the raised beaches on storøya, an 129blake 2006: polar research 25(2), 123–137 table 2. selected early holocene radiocarbon ages, nordaustlandet, svalbard. (table continues next page.) field no. elev. (m) lab. no. a age, reported by lab. age, corrected for apparent age of seawater γ13c (pdb) ‰ comments and collector b kinnvika, murchisonfjorden wb-90-21a 72 ua-2207 10 030 ± 110 9590 ± 110 c –21.0(assumed) partial shaft of left humerus of a polar bear (ursus maritimus). 9.3 g. w. blake, jr. wb-90-11 62 ua-2099 9930 ± 100 9490 ± 100 c –21.0(assumed) a right pelvic bone from a bearded seal (erignathus barbatus). 12.6 g. w. blake, jr south side of murchisonfjorden h/131-135 62 u-92 10 000 ± 600 — –32.0 krystallvatnet—limnic peat at 131 134 (or 118 122) cm depth in core. water depth 19 m. a. häggblom. wb-58-27 36.5 u-70 9400 ± 140 — –24.0 larix sp. log near sveanor. w. blake, jr. wb-58-27 36.5 gsc-3490 9420 ± 100 — –25.7 same log, 11.7 g dry wood. one 4-day count in 5-l counter. — 82 u-2095 11 180 ± 190 10 740 ± 190 0.3 numerous mya truncata shells, partly buried in beach material. innermost 35 % of shell material. m. g. grosswald. — 82 u-660 11 150 ± 110 10 710 ± 110 0.3(assumed) shell layer surrounding u-2095 corresponds to 40 % of shell material. outermost 25 % removed by hcl leach. lady franklinfjorden—søre franklinbreen wb-167-66 125-130 ua-905 9525 ± 130 9085 ± 130 — pelecypod shell fragment, probably chlamys islandica. calcite. 0.008 g. no leach. w. blake, jr. wb-167-66 125-130 ua-1058 9675 ± 140 9235 ± 140 — unidentifi ed pelecypod shell fragment. aragonite. 0.16 g. outermost 50 % removed by hcl leach. dalvågen wb-41-66 18 gsc-2729 9670 ± 200 9670 ± 200 2.6 chlamys islandica (intact pair), same site. outermost 10 % of shell removed by hcl leach. calcite, aragonite and rhodocrosite 10.25 g. wb-41-66 18 ua-341 9950 ± 200 9510 ± 200 — chlamys islandica (single fragment), same site. cal-cite. 0.04 g. innermost 5 % of shell used for dating. wb-64-66 23 ua-902 9720 ± 115 9280 ± 115 — balanus balanus calcite. 0.07 g. inner 50 % of shell used for dating. w. blake, jr. north end prins oscars land, near arkvatnet — 22 st-7989 9465 ± 120 — –26.8 driftwood log. h. österholm & v. schytt. rijpdalen wb-120-66 32-36 gak-1915 9200 ± 180 9200 ± 180 — mya truncata shells in river section, south of the head of rijpfjorden. 47.0 g. w. blake, jr. wb-120-66 32-36 gsc-2669 9100 ± 140 9100 ± 140 0.3 mya truncata shells in river section, same site. outer most 20 % of shell removed by hcl leach. 26.9 g. wahlenbergfjorden wb-187-66 ∼43 gsc-2736 9670 ± 140 9670 ± 140 3.6 single right valve of mya truncata. outermost 10 % of shell removed by hcl leach. aragonite. 12.0 g. marine limit at ∼66 m. w. blake, jr. 130 mytilis edulis on nordaustlandet, svalbard island east of nordaustlandet, is 9685 ± 125 14c yr bp (st-7825, jonsson 1983; also reported uncorrected for δ13c in häggblom 1982a, 1982b). this result was obtained on a driftwood log at 53.3 m a.s.l. the beach at this level, as with all other raised beaches on storøya, disappears under the ice cap that occupies the southern half of the island, showing that the ice cap has developed, again, in latest holocene time (schytt 1981). at svartknausfl ya, south-western nordaustlandet, wil low wood at 65.5 m a.s.l. dates from 9550 ± 80 14c yr bp (t-2503; salvigsen 1978, 1979). it is thus clear that by 9500 to 9000 14c yr bp, coasts all around nordaustlandet had become free of glacier ice. however, with the exception of innermost wahlenbergfjorden, m. edulis has not been found at any of these locations. nor was any trace of mytilus found at the other north coast sites visited in the wide-ranging 1966 surveys carried out by the writer, namely at lady franklin fjorden, lindhagenbukta, sabinebukta, rijp fjorden, zorgdrager fjorden, finn malmgrenfjorden, søre repøya, and sjuøyane (fig. 1). data from hinlopenrenna, the trough across the continental shelf to the north of hinlopenstretet and north-west of nordaustlandet, are as follows: 1) shells of chlamys islandica ca. 1.2 m below the seabed and above coarse sediments interpreted as glaciomarine in core po 7817 (80° 11' n, 16° 40' e; 205 m water depth), some 17.5 km north-west of langgrunnodden, are 9010 ± 140 14c yr bp (t-3103; salvigsen & nydal 1981); and 2) where hinlopenrenna intersects the edge of the continental shelf, ca. 36.5 km northwest of langgrunnodden, benthic foraminifera at 690 699 cm in core np 94-51sc2 (80° 21.35' n, 16° 17.970' e, 400 m water depth) are 13 725 ± 135 14c yr bp (tua-3587; koç et al. 2002; this age is listed in uncorrected form as 14 162 ± 135 14c yr bp in ślubowska et al. 2005). discussion oceanographic conditions and glacier recession with regard to the question of lower and more variable salinity in coastal waters, proposed by feder et al. (2003) as important to the distribution of mytilus in northern alaska, a few observations are pertinent. as shown in fig. 2, the north-west corner of nordaustlandet, between kinnvika and langgrunnodden, has an intricate and low-lying coastline, developed in carbonate rocks of the roaldtoppen group (flood et al. 1969; sandelin et al. 2001). this gently shelving coast, characterized by the presence of numerous shoals (binney 1926), lagoons and both bay-head and bay-mouth bars, is the area where all of the writer’s colfield no. elev. (m) lab. no. a age, reported by lab. age, corrected for apparent age of seawater δ13c (pdb) ‰ comments and collector b storøya 7 53.3 st-7825 9685 ± 125 — –26.4 driftwood log. a häggblom. svartknausfl ya 30 65.5 t-2503 9550 ± 80 — — salix sp. wood 1 m long on ground surface. o. salvigsen. a laboratory designations: u = uppsala; ua = tandem accelerator laboratory, uppsala; st = natural history museum, stockholm; gak = gakushuin university, japan; gsc = geological survey of canada, ottawa; t = trondheim. see footnote d, table 1, with regard to gakushuin results. laboratory reported ages from u, ua, st and t are normalized to a base of δ13c = –25.0 ‰. marine shell samples processed at gsc and gak are corrected to δ13c = 0.0 ‰, so no additional correction is applied (lowdon 1985; blake 1987; kigoshi et al. 1963). b identifi cations of bones: c. r. harington, canadian museum of nature, ottawa; shells: w. blake, jr., geological survey of canada, ottawa (except for u-2095); driftwood from sveanor: g. w. burns, ohio wesleyan university, delaware, oh c here the same correction (–440 years) is used as for marine molluscs. håkansson (1974) reports an apparent age of 480 ± 70 years (lu-715) for the cranium of a young polar bear collected in 1989 in inner isfjorden, but time of death is estimated at 50 ± 50 years. thus the “apparent age” for mammals whose diet is marine organisms may have to be modifi ed when additional data become available. table 2, continued from previous page. 131blake 2006: polar research 25(2), 123–137 lections of mytilus have been made. no signifi cant rivers reach this part of the coast. early in holocene time, when the peninsulas now exposed because of glacial rebound would have been beneath the sea, conditions closer to full marine might have prevailed, as they do offshore today under the infl uence of north atlantic water of the atlantic current (loeng 1991). this atlantic layer is conveyed northward and then eastward by a strong boundary current, the west spitsbergen current. north of hinlopenstretet the core of the atlantic layer occurs at 100 to 400 m depth, with temperatures of 3 to 4.5 °c and salinities of 34.4 to 35.0 ‰ (koç et al. 2002; ślubowska et al. 2005; see also fig. 2 in peacock 1989). furthermore, under early holocene conditions of rapid rebound, there would have been little time available for lagoons and bars to develop. some 9200 to 8700 14c yr bp and perhaps until ca. 1000 14c yr bp (blake 1987, 1989), the front of søre franklinbreen at the head of lady franklinfjorden is known to have been several kilometres behind (south-east of) the various positions that it has occupied since 1899 (de geer 1923; moss & glen 1939; blake 1962, 1989). that is, at the time that mytilus reached the north-west coast of nordaustlandet, this major source of freshwater would have been even more distant from langgrunnodden and kinnvika than it is today, if in fact this outlet glacier continued to exist at all. in this connection koerner concluded that the svalbard ice caps, among others, “consist entirely of holocene ice indicating that their re-growth began during some part of the holocene, as the climate cooled” (1999: 81). nonetheless, the yearly melting of sea ice, plus runoff from the land, clearly must have resulted in at least some temporary reduction in salinity in the shallow water along the outermost coasts where mytilus has been found in considerable abundance on the raised beaches. but were the waters any less saline at that time than they are today, and what effect did any changes in salinity have on the abundance of predators (cf. feder et al. 2003)? as an example of conditions during the international geophysical year (1957–58), on 18 july 1957, the finnish ship rv aranda occupied hydrographic station no. 35 in kinnvika, murchisonfjorden (80° 03' n, 18° 15' e). salinities and water temperature were as follows: surface (33.96 ‰; 2.67 °c); 10 m depth (34.39 ‰; 2.01 °c), 15 m depth (34.44 ‰; 1.88 °c) and 20 m depth (34.48 ‰; 1.78 °c; hela & koroleff 1958). yet no evidence has been found by the writer that kinnvika harbours mytilus edulis today, either as living colonies or individuals cast up on the modern beaches attached to marine algae. the same is true for the langgrunnodden–detterbukta area. also, the mytilus collections from the raised beaches in these areas showed no evidence of drilling by naticid or other predatory snails. the confi guration of wahlenbergfjorden is very different from the topography of the outer coast between kinnvika and langgrunnodden. the 40 to 45 km long wahlenbergfjorden extends deeply into nordaustlandet, reaching close to the geographical centre of the island (fig. 1). glaciers enter the head of the fjord from high land to the north, east and south, and rivers draining the southern half of rijpdalen, as well as the adjacent ice caps, provide additional freshwater. some 7400 to 6900 14c yr bp, when mytilus lived at the head of the fjord, that area still would have received signifi cant runoff from the land even though the ice caps and glaciers were much reduced in size, or perhaps absent. basic oceanographic data for hinlopenstretet and wahlenbergfjorden, plus some information for murchisonfjorden, were provided by mosby (1938), as a result of his work aboard quest during the course of the swedish–norwegian arctic expedition in the summer of 1931. hydrographic stations on both the north and south sides of søre russøya (24 and 30 june, respectively), yielded salinities in the 33.84 to 34.29 ‰ range with most temperatures slightly negative at depths between 0 and 25 m (mosby 1938, table 1). mosby noted with regard to murchisonfjorden, “it thus appears that these waters are extensively diluted by melting water from land, from the glaciers” (p. 61). fig. 4. typical occurrence of mytilus fragment (arrow) in beach gravel at kinnvika; part of sample wb-90-25 at 5.1 m a.s.l. (table 1). knife for scale is 9 cm in length. (photograph by w. blake, jr., 27 july 1990.) 132 mytilis edulis on nordaustlandet, svalbard data for 10 hydrographic stations spread over the length of hinlopenstretet were also presented: at station 94, west of langgrunnodden, the surface water had a salinity of 33.57 ‰ on 17 august 1931, and the values increased progressively with depth to a maximum of 34.98 ‰ at 200 m; temperatures ranged between 3.45 and 5.13 °c. mosby (1938) also stressed the fact that salinities at the most easterly stations (6 and 7) in wahlenbergfjorden were lower (all < 34.0 ‰ at 0 to 10 m depth, with negative temperatures throughout) than at station 13 in hinlopenstretet outside the mouth of the fjord (due south of brageneset; see fig. 1), where all salinity values were above 34.0 ‰ and temperatures ranged between –0.89 and 0.71 °c (0 to 250 m depth, 3–4 july 1931). although mosby does not comment with regard to the salinities in inner wahlenbergfjorden, presumably the same conclusion can be reached that he did for murchisonfjorden. according to peacock (1993), m. edulis, in open sea conditions at the northern limit of its distribution, requires a minimum summer sea surface temperature of 4 °c. palaeoceanographic implications the age determinations on mytilus shells from north-western nordaustlandet show that this pelecypod lived north of the 80th parallel for much of the fi rst half of holocene time. the arrival of mytilus to nordaustlandet coincided with the fi rst infl ux of subpolar north atlantic water recorded in core pcm7 (78° 37' n, 7° 54' e) at 1073 m depth off the west coast of spitsbergen (lloyd et al. 1996). these authors state: “this initial period of subpolar water infl uence along the spitsbergen margin lasted until approximately 9 ka...” (p. 297). the information gleaned from this core agrees with the earlier conclusion by svendsen & mangerud (1992) that a phase of rapid glacial retreat in the inner fjords of spitsbergen and in eastern svalbard occurred at the beginning of the holocene. farther south, off the western barents shelf at 75° n, sarnthein et al. (2003) calculated that the major postglacial warming of the west spitsbergen current, by 4 to 5 °c, occurred in early holocene time. salvigsen (2002) has suggested that mytilus was most widespread in svalbard at ca. 7250 14c yr bp, a conclusion based in part on the one age determination available to him from wahlenbergfjorden. had more extensive and more detailed collections been made in north-western nordaustlandet, with a whole series of sub-collections selected across the altitudinal range at which the shells occur at each site, and if a signifi cantly greater number of age determinations had been carried out, it might have been possible to determine with certainty whether mytilus lived along hinlopenstretet continuously for some 3000 years or whether it colonized the island on more than one occasion. the series of 14 radiocarbon ages on mytilus shells from the hiorthfjellet fan delta, on spitsbergen, ranging from 6175 ± 90 (t13345) to 4350 ± 110 (t-13358) 14c yr bp (lønne & nemec 2004), for example, clearly shows the continuous presence of mytilus at this site on the south side of isfjorden. on the northern coast of spitsbergen mytilus had appeared by ca. 9300 14c years bp (salvigsen & österholm 1982; brückner & halfar 1994; salvigsen 2002), that is, slightly earlier than on nordaustlandet. then mytilus persisted in northern spitsbergen for another 500 years—until ca. 5300 14c yr bp (salvigsen 2002)—in the innermost, southern part of one of the main, north coast fjords. nearly all of the ages on mytilus from nordaustlandet fall within the interval of ca. 8800 to 5000 14c yr bp when this species also was present on edgeøya, in south-eastern svalbard (hjort et al. 1992; hjort et al. 1995). the interval from ca. 8000 to 4000 14c yr bp is the time when the mean july temperatures in outer isfjorden, based on the analysis of macrofossils in lake sediments, may have been at least 1.5 °c higher than today (birks 1991). in addition, the interval from 8400 to 4900 14c yr bp corresponds to the time when six boreal mollusc species colonized a section of the west greenland coast between 65° 30' n and 68° 30' n (funder & fredskild 1989; funder & weidick 1991), and a similar interval of roughly 8000 to 5500 14c yr bp for colonization by mytilus was reported from the central east greenland coast by hjort & funder (1974). these authors suggested that mytilus may have reached central east greenland via a branch of the west spitsbergen current, which brought warm atlantic water to the coast at a time when the cold polar east greenland current was diminished in strength. this hypothesis is supported by an analysis of stable isotope composition of water samples and bivalve shells in east greenland. israelson & buchardt concluded that: “a higher salinity in scoresby sund and in the coastal waters of germania land in 133blake 2006: polar research 25(2), 123–137 the early holocene has been demonstrated. this is in agreement with the studies of hjort & funder (1974) who postulated that the immigration of mytilus edulis to the east greenland fjords during this time was connected with an infl uence of atlantic water, more saline than the present coastal waters of east greenland” (1991: 121–122). further, dyke et al. (1996) note that a shift westward in the transpolar drift may result in both the east and west greenland currents becoming warmer. comparison with baffi n bay an analogous situation to nordaustlandet exists in northernmost baffi n bay. in 1940 m. edulis was found living intertidally at north star bugt in the thule district, north-west greenland (ca. 76° 30' n; vibe 1950). later, in 1968, living individuals of mytilus were collected at several additional sites in the thule district and, in 1973, farther north at siorapaluk in robertson fjord (ca. 77° 46' n), where these pelecypods were used by the local population as food (theisen 1973). by contrast, no living mytilus or fossil shells have been found on the ellesmere island side of northernmost baffi n bay at similar latitudes (dale 1985; blake 1992, 1993). however, near the southern end of coburg island (75° 52.5' n), at the entrance to jones sound and some 40 km from devon island, mytilus was collected from a coastal section by the writer in 1970 and 1972. two radiocarbon age determinations were made on these shells: the blue, outer prismatic layer (calcite) yielded an age of > 38 000 14c yr bp (gsc1425; blake 1973), whereas the inner nacreous material (aragonite) from the same shells, dated later by ams, yielded an age of 46 070 ± 830 14c yr bp (to-3991). no mytilus shells were discovered in the richly fossiliferous holocene strata overlying the “old” shells, nor were any modern shells of this species found along the presentday shores of coburg island or along the southern coast of ellesmere island. on the greenland side, by contrast, both pre-holocene and holocene occurrences of mytilus are known from the north star bugt area, thule district (davies et al. 1963; blake 1975; funder & fredskild 1989; funder 1990). these northern occurrences of mytilus along the baffi n bay coast of greenland are a consequence of the northward fl owing warm water of the west greenland current which, like the west spitsbergen current in svalbard, carries the pelagic mytilus larvae northward. in the case of greenland, the pelagic larvae originate in southern west greenland, where mytilus is widespread (madsen 1936; funder & símonarson 1984), whereas in svalbard, the larvae presumably originate in northern norway (berge et al. 2005; berge et al. 2006). on the canadian side of baffi n bay, cooled by the southward fl owing baffi n current (funder 1990), recent mytilus has not been found north of the pond inlet area, northern baffi n island, at approximately 72° 41' n, some 500 km south-west of the thule district and 350 km south of coburg island (nichols 1936; laursen 1946; ellis 1955; lubinsky 1980). radiocarbon age determinations of mytilus collected from the modern beach near the hamlet of pond inlet in 1963 by b. g. craig were 80 ± 220 and 340 ± 90 14c yr bp (gsc-1570 and -1898, respectively); another sample collected in roughly the same area in 1923 yielded an age of 1210 ± 330 14c yr bp (gsc-1583; all in blake 1987). the occurrence of mytilus at this latitude results from the counter-clockwise circulation which brings the warmer waters of the west greenland current to the west side of northern baffi n bay (kiilerich 1939; dunbar 1972; funder 1990; funder & weidick 1991). mytilus shells of holocene age, based on stratigraphy, also have been found in the vicinity of pond inlet. to the west shells were found in a river-cut section at about 15 m a.s.l. (klassen 1993), and to the east shell fragments were found among rounded pebbles on a raised beach at about 26 m a.s.l. (d. a. hodgson pers. comm. 2006). conclusions the timing of the arrival of mytilus in northwestern nordaustlandet agrees with the proposal by lloyd et al. (1996) that the fi rst penetration of subpolar north atlantic waters occurred off the western margin of spitsbergen at the beginning of the holocene. according to their results, based on a study of two cores, “the faunal data suggest this period, until approximately 9 ka bp, was as warm if not warmer than the present day along the spitsbergen margin” (p. 299). the drastic warming in early holocene time, well documented from ice caps as far afi eld from svalbard as arctic canada (koerner & fisher 1990, 1995, 134 mytilis edulis on nordaustlandet, svalbard 2002), resulted in rapid recession of glaciers all around nordaustlandet and probably caused the disappearance, or near disappearance, of the ice caps on this island. this same warming allowed mussels of the m. edulis complex to colonize the coasts of spitsbergen via the west spitsbergen current, reaching north-western nordaustlandet by 9000 14c yr bp. the lower salinities which resulted from the massive melt-off of glaciers may have played a role in the spread of mytilus along the coasts of svalbard in early holocene time, but the warming and intensity of the west spitsbergen current itself must be regarded as the driving force. on the basis of their study of core np94-51sc2 in hinlopenrenna, only 36.5 km north-west of langgrunnodden, the northernmost site where mytilus was collected, ślubowska et al. (2005) conclude that: “during the late holocene the infl ow of warm water masses carried by the west spitsbergen current decreased to a very low level. conditions at the surface and bottom water were polar with low salinity and extensive sea ice cover and marked by the readvance of glaciers on svalbard” (2005: 13). this statement is consistent with the evidence presented here for the disappearance of mytilus from nordaustlandet after ca. 5800 14c yr bp. acknowledgements.—the writer’s participation in the expeditions to nordaustlandet was made possible by grants from the foreign field research program, national academy of sciences—national research council (1957 and 1958) and from the arctic institute of north america (1966). in both cases funds were provided by the us offi ce of naval research. other major funding for these expeditions, as well as that in 1990, came from the swedish natural science research council), the swedish society for anthropology and geography, the swedish polar research secretariat and the national geographic society (grant no. 4068-89). logistical support was provided by the finnish institute of marine research (aranda), the swedish navy (älvsnabben, under kommendörkapten, now amiral, b. lundvall, ret.), both norwegian and swedish air forces, the offi ce of the governor of svalbard and the norwegian polar institute (t. gjelsvik & k. z. lundquist; ships sjøvern and minna). helicopter support in 1966 was provided by a contingent from the swedish army (major b. hasselrot), and the norwegian coast guard (kv senja) put out a fuel depot for the 1990 expedition. excellent assistance in the fi eld was provided by r. bergström (1958) and h. billeström (1966). the joint leader in 1990, professor w. karlén, as well as e. skye, p.-o. isaksson and k. gjerde, all helped with levelling. i am particularly indebted to the late professors v. schytt, g. hoppe & g. h. liljequist for making it possible for me to participate in these expeditions and for their sustained interest and support over several decades. p. jeffery, assistant curator of geology at the oxford university museum of natural history, kindly arranged for the loan of k. s. sandford’s samples from wahlenbergfjorden. radiocarbon dating was carried out at laboratories as indicated; special thanks go to i. u. olsson and g. possnert at their respective laboratories in uppsala, j. a. lowdon (geological survey of canada, ottawa) and j. southon (university of california at irvine). h. f. aas, at the norwegian polar institute, was helpful in connection with the aerial photograph. h. m. feder, institute of marine research, and d. w. norton, school of fisheries and ocean science, both university of alaska at fairbanks, provided good discussion about mytilus as well as perceptive remarks on the manuscript. in addition, valuable comments and suggestions for improvement have been made by the journal referees: s. bondevik, university of tromsø; s. funder, geological museum, university of copenhagen; and c. hjort, university of lund. o. salvigsen, university of oslo, called my attention to several pertinent issues of svalbardposten. at the geological survey of canada, t. barry prepared the illustrations, s. parnham processed the manuscript and d. a. hodgson provided a most helpful internal review. this article is geological survey of canada contribution 2005696. references berge, j., johnsen, g., nilsen, f., gulliksen, b. & slagstad, d. 2005: ocean temperature oscillations enable reappearance of blue mussels mytilus edulis to svalbard after a 1000 year absence. mar ecol. prog. ser. 303, 167–175. berge, j., johnsen, g., nilsen, f., gulliksen, b., slagstad, d. & pampanin, d. m. 2006: the mytilus edulis population in svalbard: how and why. mar. ecol. prog. ser. 309, 305–306. binney, g. 1926: with seaplane and sledge in the arctic. new york: g. h. doran co. birks, h. h. 1991: holocene vegetational history and climatic change in west spitsbergen—plant macrofossils from skardtjørna, an arctic lake. the holocene 1, 209–218. blake, w., jr. 1961a: radiocarbon dating of raised beaches in nordaustlandet, spitsbergen. in g. o. raasch (ed.): geology of the arctic. pp. 133–145. toronto: university of toronto press. blake, w., jr. 1961b: russian settlement and land rise in nordaustlandet, spitsbergen. arctic 13, 101–111. blake, w., jr. 1962: geomorphology and glacial geology of nordaustlandet, spitsbergen. phd thesis, ohio state university, columbus, oh. blake, w., jr. 1973: former occurrence of mytilus edulis l. on coburg island, arctic archipelago. nat. can. 100, 51–58. blake, w., jr. 1975: glacial geological investigations in northwestern greenland. geol. surv. can. pap. 75-1a, 435–439. blake, w., jr. 1980: radiocarbon dating of driftwood; inter135blake 2006: polar research 25(2), 123–137 laboratory checks on samples from nordaustlandet, svalbard. geol. surv. can. pap. 80-1c, 149–154. blake, w., jr. 1981: glacial history of svalbard and the problem of the barents shelf ice sheet: comments. boreas 10, 125–128. blake, w. jr. 1987: geological survey of canada radiocarbon dates xxvi. geol. surv. can. pap. 86-7. geological survey of canada. blake, w., jr. 1989: radiocarbon dating by accelerator mass spectrometry; a contribution to the chronology of holocene events in nordaustlandet, svalbard. geogr. ann. 71a, 59–74. blake, w., jr. 1992: holocene emergence at cape herschel, east-central ellesmere island, arctic canada: implications for ice sheet confi guration. can. j. earth sci. 29, 1958– 1980. blake, w., jr. 1993: holocene emergence along the ellesmere island coasts of northernmost baffi n bay. nor. geol. tidsskr. 78, 147–160. blake, w., jr. 1995: a historical perspective of radiocarbon dating for nordaustandet, svalbard. in t. hackens et al. (eds.): 14c methods and applications. pact 49, 107–116. blake, w., jr. 1996: a report on investigations into the glacial history of northwestern nordaustlandet, svalbard, 1990. unpubl. report to the national geographic society, washington, d.c. brückner, h. & halfar, r. a. 1994: evolution and age of shorelines along woodfjord, northern spitsbergen. z. geomorphol. n. f., suppl.bd. 97, 75–91. christiansen, b. o. 1965: notes on the littoral fauna of bear island. astarte 26, 1–15. chydenius, k. 1865: svenska expeditionen till spetsbergen år 1861. (swedish expedition to spitsbergen in the year 1861.) stockholm: p. a. norstedt & söner. dale, j. e. 1985: recent intertidal molluscs from the east-central coast of ellesmere island, northwest territories. geol. surv. can. pap. 85-1b, 319–324. davies, w. e., krinsley, d. b. & nicol, a. h. 1963: geology of the north star bugt area, northwest greenland. medd. grønl. 162(12). copenhagen: danish polar center. deevey, e. s., jr., flint, r. f. & rouse, i. 1967: deevey, e. s., jr., flint, r. f. & rouse, i. 1967: radiocar-radiocarbon measurements: comprehensive index, 1950–1965. bon measurements: comprehensive index, 1950–1965. american journal of science.american journal of science. new haven: yale universinew haven: yale university press.ty press. de geer, g. 1923: topographie, géologie (topography, geology). missions scientifi ques pour la mesure d’un arc de méridien au spitzberg, entreprises in 1899-1902 sous les auspices des gouvernements suédois et russe, mission suédoise. tome 2, 9e sect. (scientifi c missions to measure an arc of meridian on spitsbergen, undertaken in 1899–1902 under the auspices of the swedish and russian governments, swedish expedition. vol. 2, section 9.) stockholm: centraltryckeriet. donner, j. j. & west, r. g. 1957: the quaternary geology of brageneset, nordaustlandet, spitsbergen. nor. polarinst. skr. 109. oslo: norwegian polar institute. donner, j. j. & west, r. g. 1995: fluctuations of the vestfonna ice margin at brageneset, nordaustlandet, svalbard, after the last glacial maximum. bull. geol. soc. finl. 67, 29–36. dowdeswell, j. a. 1986a: drainage-basin characteristics of nordaustlandet ice caps, svalbard. j. glaciol. 32, 31–38. dowdeswell, j. a. 1986b: remote sensing of ice cap outlet glacier fl uctuations on nordaustlandet, svalbard, polar res. 4, 25–32. dunbar, m. j. 1972: the nature and defi nition of the marine subarctic, with a note on the sea-life area of the atlantic salmon. trans. r. soc. can. ser. iv, 10, 249–257. dyke, a. s., dale, j. e. & mcneely, r. n. 1996: marine molluscs as indicators of environmental change in glaciated north america and greenland during the last 18 000 years. géogr. phys. quat. 50, 125–184. ellis, d. v. 1955: some observations on the shore fauna of baffi n island, arctic 8, 224–236. elton, c. s. & baden-powell, d. f. w. 1931: on a collection of raised beach fossils from spitsbergen. geol. mag. 48, 385–405. feder, h. m., norton, d. w. & geller, j. b. 2003: a review of apparent 20th century changes in the presence of mussels (mytilus trossulus) and macroalgae in arctic alaska, and of historical and paleontological evidence used to relate mollusc distributions to climate change. arctic 57, 391–407. feyling-hanssen, r. w. 1955: stratigraphy of the marine late-pleistocene of billefjorden, vestspitsbergen. nor. polarinst. skr. 107. oslo: norwegian polar institute. feyling-hanssen, r. w. & jørstad, f. a. 1950: quaternary fossils from the sassen area in isfjorden, west-spitsbergen. nor. polarinst. skr. 94. oslo: norwegian polar institute. feyling-hanssen, r. w. & olsson, i. 1960: five radiocarbon datings of post glacial shorelines in central spitsbergen. nor. geogr. tidsskr. 17, 122–131. flood, b., gee, d. g., hjelle, a., siggerud, t. & winsnes, t. s. 1969: the geology of nordaustlandet, northern and central parts. nor. polarinst. skr. 146. oslo: norwegian polar institute. forman, s. l. & ingólfsson, ó. 2000. late weichselian glacial history and postglacial emergence of phippsøya, sjuøyane, northern svalbard: a comparison of modelled and empirical estimates of a glacial-rebound hinge line. boreas 29, 16–25. forman, s. l. & polyak, l. 1997: radiocarbon content of prebomb marine mollusks and variations in the 14c reservoir age for coastal areas of the barents and kara seas, russia. geophys. res. lett. 24, 885–888. funder, s. 1978: holocene stratigraphy and vegetation history in the scoresby sund area, east greenland. bull. grønl. geol. unders. 129. copenhagen: geological survey of denmark and greenland. funder, s. 1990: molluscs, barnacles and other marine and terrestrial fauna and fl ora. in s. funder (ed.): late quaternary stratigraphy and glaciology of the thule area, northwest greenland. medd. grønl. geosci. 22, 23–32. funder, s. 1992: latest weichselian and early holocene mollusc faunas from eastern svalbard, palaeoceanographic implications. in p. möller et al. (eds.): weichselian & holocene glacial and marine history of east svalbard: preliminary report on the ponam fi eldwork in 1991. lundqua rep. 35, 131–137. funder, s. & fredskild, b. 1989: paleofaunas and fl oras (greenland). in r. j. fulton (ed.): quaternary geology of canada and greenland. geol. surv. can. v. k-1, 775–783. funder, s. & símonarson, l. a. 1984: bioand aminostratigraphy of some quaternary marine deposits in west greenland. can. j. earth sci. 21, 843–852. funder, s. & weidick, a. 1991: holocene boreal molluscs in greenland—palaeoceanographic implications. palaeogeogr. palaeoclimatol. palaeoecol. 85, 123–135. hägg, r. 1950: kvartära marina fossil från spetsbergen insam136 mytilis edulis on nordaustlandet, svalbard lade av svenska expeditioner. (quaternary marine fossils from spitsbergen collected by swedish expeditions.) geol. fören. stockholm förh. 72, 331–347. häggblom, a. 1963: sjöar på spetsbergens nordostland. (lakes on spitsbergen’s nordaustlandet.) ymer 83, 76–105. häggblom, a. 1982a: flytande ved och drivande is i arktis. (floating wood and drifting ice in the arctic.) fauna flora 77, 121–128. häggblom, a. 1982b: driftwood on svalbard as an indicator of sea ice conditions. geogr. ann. 64a, 81–94. håkansson, s. 1974: university of lund radiocarbon dates vii. radiocarbon 16, 307–330. heintz, a. 1926: blåskjell på spitsbergen. (mussels on spitsbergen.) nor. geol. tidsskr. 9, 74–76. hela, i. & koroleff, f. 1958: hydrographical and chemical data collected in 1957 on board the r/v aranda in the barents sea. merentutk.l. julk. 179. helsinki: finnish institute of marine research. hjort, c., adrielsson, l., bondevik, s., landvik, j. t., mangerud, j. & salvigsen, o. 1992: mytilus edulis on eastern svalbard—dating the holocene atlantic water infl ux maximum. in p. möller et al. (eds.): weichselian & holocene glacial and marine history of east svalbard: preliminary report on the ponam fi eldwork in 1991. lundqua rep. 35, 171–175. hjort, c. & funder, s. 1974: the subfossil occurrence of mytilus edulis l. in central east greenland. boreas 3, 23–33. hjort, c., mangerud, j., adrielsson, l., bondevik, s., landvik, j. y. & salvigsen, o. 1995: radiocarbon dated common mussels mytilus edulis from eastern svalbard and the holo cene marine climatic optimum. polar res. 14, 239–243. hoel, a. 1909: geologiske iagttagelser paa spitsbergenekspeditionerne 1906 og 1907. (geological observations on spitsbergen expeditions 1906 and 1907.) nor. geol. tidsskr. 1, 3–28. högbom, b. 1911: bidrag till isfjordsområdets kvartärgeologi. (contribution to the quaternary geology of the is fjord area.) geol. fören. stockholm förh. 33, 32–57. högbom, b. 1913: om spetsbergens mytilustid. (on spitsbergens mytilus period.) geol. fören. stockholm förh. 35, 151–156. hoppe, g. 1987: om israndrännor och strandlinjer på wargentinfl ya. (on lateral drainage channels and strandlines on wargentinfl ya.) in g. hoppe et al. (eds.): expeditionen ymer 80, en slutrapport. (the ymer 80 expedition, fi nal report.) pp. 113–117. stockholm: royal swedish academy of sciences, polar research committee. israelson, c. & buchardt, b. 1991: the isotopic composition of oxygen and carbon in some fossil and recent bivalve shells from east greenland. in p. möller et al. (eds.): the last interglacial-glacial cycle: preliminary report on the ponam fi eldwork in jameson land and scoresby sund, east greenland. lundqua rep. 33, 117–123. jonsson, s. 1983: on the geomorphology and past glaciation of storöya, svalbard. geogr. ann. 65a, 1–17. karlén, w. 1987: geomorfologi, glaciologi och istidsförlopp på östra svalbard. (geomorphology, glaciology and the course of the ice age in eastern svalbard.) in g. hoppe et al. (eds.): expeditionen ymer 80, en slutrapport. (the ymer 80 expedition, fi nal report.) pp. 88–92. stockholm: royal swedish academy of sciences, polar research committee. karlén, w. 1994: deglaciation and climate change. in a. karlqvist & m. l. carlsson (eds.): swedish research in svalbard—a cruise report. pp. 118–123. stockholm: swedish polar research secretariat. kelly, m. 1985: a review of the quaternary geology of western greenland. in j. t. andrews (ed.): quaternary environments, eastern canadian arctic, baffi n bay and western greenland. pp. 461–501. boston: allen & unwin. kigoshi, k., tomikura, y. & endo, k. 1962: gakushuin natural radiocarbon measurements i. radiocarbon 4, 84–94. kiilerich, a. f. 1939: the godthaab expedition 1928. a theoretical treatment of the hydrographical observation material. medd. grønland 78(5). copenhagen: danish polar center. klassen, r. a. 1993: quaternary geology and glacial history of bylot island, northwest territories. geol. surv. can. mem. 429. geological survey of canada. koç, n., klitgaard-kristensen, d., hasle, k., forsberg, c. f. & solheim, a. 2002: late glacial palaeoceanography of hinlopen strait, northern svalbard. polar res. 21, 307–314. koerner, r. m. 1999: climate and the ice core record: arctic examples. in a. g. lewkowicz (ed.): poles apart: a study in contrasts. pp. 71–87. ottawa: university of ottawa press. koerner, r. m. & fisher, d. a. 1990: a record of holocene summer climate from a canadian high-arctic ice core. nature 343, 630–631. koerner, r. m. & fisher, d. a. 1995: the greenland ice sheet record: insensitive to holocene climatic change? in: wadati conference on global change and the polar climate. (programme and preprints.) tsukuba science city, japan, 7–10 november 1995. pp. 74–77. koerner, r. m. & fisher, d. a. 2002: ice-core evidence for widespread arctic glacier retreat in the last interglacial and the early holocene. ann. glaciol. 35, 19–24. kristiansen, k. j. & sollid, j. l. 1986: svalbard, glacialgeologisk -og geomorfologisk kart 1:1 000 000. (svalbard, glacial–geological and geomorphological map 1:1 000 000.) nasjonalatlas for norge. oslo: institute of geography, university of oslo. kulling, o. 1936: scientifi c results of the swedish–norwegian arctic expedition in the summer of 1931. part xii:1. observations on raised beaches and their faunas. geogr. ann. 18, 1–7. laursen, d. 1946: quaternary shells collected by the fifth thule expedition 1921–24. report of the fifth thule expedition 1921–24, 1, no. 7. copenhagen: gyldendalske boghandel, nordisk forlag. lefauconnier, b. & hagen, j. o. 1991: surging and calving glaciers in eastern svalbard. nor. polarinst. medd. 116. oslo: norwegian polar institute. lloyd, j., kroon, d., laban, c. & boulton, g. 1996: deglaciation history and palaeoceangraphy of the western spitsbergen margin since the last glacial maximum. in j. t. andrews et al. (eds.): late quaternary palaeoceanography of the north atlantic margins. geol. soc. lond. spec. publ. 111, 289–301. loeng, h. 1991: features of the physical oceanographic conditions of the barents sea. polar res. 10, 5–18. lønne, i. & nemec, w. 2004: high-arctic fan delta recording deglaciation and environment disequilibrium. sedimentology 51, 553–589. lowdon, j. a. 1985: the geological survey of canada radiocarbon dating laboratory. geol. surv. can. pap. 84-24. geological survey of canada. 137blake 2006: polar research 25(2), 123–137 lubinsky, i. 1980: marine bivalve molluscs of the canadian central and eastern arctic: faunal composition and zoogeography. can. bull. fish. aquat. sci. 207. madsen, h. 1936: investigations on the shore fauna of east greenland with a survey of the shores of other arctic regions. medd. grønl. 100(8). copenhagen: danish polar center. mangerud, j. & gulliksen, s. 1975: apparent radiocarbon ages of recent marine shells from norway, spitsbergen and arctic canada. quat. res. 5, 263–273. mangerud, j. & svendsen, j. i. 1992a: the last interglacial– glacial period on spitsbergen, svalbard. quat. sci. rev. 11, 633–664. mangerud, j. & svendsen, j. i. 1992b: the last interglacial/ glacial cycle on svalbard, as seen from the kapp ekholm section. in v. m. kotlyakov & v. e. sokolov (eds.): arctic research, advances and prospects. part 2. pp. 63–66. moscow: commission on the arctic research, academy of sciences of the ussr. mosby, h. 1938: svalbard waters. geofys. publ. 12(4). oslo: norwegian academy of sciences. moss, r. & glen, a. r. 1939: the retreat of the franklin glacier, north east land. geogr. j. 93, 228–229. nathorst, a. g. 1901a: bidrag till kung karls lands geologi. (contribution to the geology of king karl’s land.) geol. fören. stockholm förh. 23, 341–378. nathorst, a. g. 1901b: bidrag till nordostra grönlands geologi. (contribution to the geology of northeast greenland.) geol. fören. stockholm förh. 23, 275–305. neilson, a. h. 1968: vascular plants from the northern part of nordaustlandet, svalbard. nor. polarinst. skr. 143. oslo: norwegian polar institute. nichols, p. a. 1936: post-pleistocene fossils of the uplifted beaches of the eastern arctic regions of canada. can. field-nat. 50, 127–129. noe-nygaard, a. 1932: remarks on mytilus edulis l. in raised beaches in east greenland. medd. grønl. 95(2). copenhagen: danish polar center. norton, d. w. & feder, h. m. 2006: mytilus thermophily? mar. ecol. progr. ser. 309, 301–303. odhner, n. j. 1915: die molluskenfauna des eisfjordes. (the molluscan fauna of isfjorden.) k. sven. vetenskapsakad. handl. 54, no. 1, part 2. stockholm: royal swedish academy of sciences. olsson, i. 1959: uppsala natural radiocarbon measurements i. am. j. sci. radiocarbon suppl. 1, 87–102. olsson, i. 1960: uppsala natural radiocarbon measurements ii. am. j. sci. radiocarbon suppl. 2, 112–128. olsson, i. u. 1980: content of 14c in marine mammals from northern europe. radiocarbon 22, 662–675. olsson, i. & blake, w., jr. 1962: problems of radiocarbon dating of raised beaches, based on experience in spitsbergen. nor. geogr. tidsskr. 18, 47–64. olsson, i., cazeneuve, h., gustavsson, j. & karlén, i. 1961: uppsala natural radiocarbon measurements iii. radiocarbon 3, 81–85. olsson, i. u., el-gammal, s. & göksu, y. 1969: uppsala natural radiocarbon measruements ix. radiocarbon 11, 515–544. peacock, j. d. 1989: marine molluscs and late quaternary environmental studies with particular reference to the lateglacial period in northwest europe: a review. quat. sci. rev. 8, 179–192. peacock, j. d. 1993: late quaternary marine mollusca as palaeoenvironmental proxies: a compilation and assessment of basic numerical data for ne atlantic species found in shallow water. quat. sci. rev. 12, 263–275. salvigsen, o. 1978: holocene emergence and fi nds of pumice, whalebones and driftwood at svartknausfl ya, nordaustlandet. nor. polarinst. årb. 1977, 217–228. salvigsen, o. 1979: datering av hevede strandlinger på svalbard. (dating of raised strandlines in svalbard.) in r. nydal et al. (eds.): førtiden i søkelyset; datering med 14c metoden g jennom 25 år. (the past in the spotlight: 25 years of 14c dating.) pp. 263–270. trondheim: radiological dating laboratory, university of trondheim. salvigsen, o. 2002: radiocarbon-dated mytilus edulis and modiolus modiolus from northern svalbard: climatic implications. nor. geogr. tidsskr. 56, 56–61. salvigsen, o. 2005: om blåskjell på svalbard nå og før. (mussels in svalbard, now and in the past). svalbardposten 20, 15. salvigsen, o., forman, s. l. & miller, g. h. 1992: thermophilous molluscs on svalbard during the holocene and their paleoclimatic implications. polar res. 11, 1–10. salvigsen, o. & høgvard, k. 2005: glacial history, holocene shoreline displacement and palaeoclimate based on radiocarbon ages in the area of bockfjorden, north-western spitsbergen, svalbard. polar res. 25, 15–24. salvigsen, o. & nydal, r. 1981: the weichselian glaciation in svalbard before 15,000 b.p. boreas 10, 433–446. salvigsen, o. & österholm, h. 1982: radiocarbon dated raised beaches and glacial history of the northern coast of spitsbergen, svalbard. polar res. 1, 97–115. sandelin, s., tebenkov, a. m. & gee, d. g. 2001: the stratigraphy of the lower part of the neoproterozoic murchisonfjorden supergroup in nordaustlandet, svalbard. gff 123, 113–127. sandford, k. s. 1929: the glacial conditions and quaternary history of north-east land. geogr. j. 74, 451–470, 543– 552. sarnthein, m., van krefeld, s., erlenkeuser, h., grootes, p. m., kucera, m., pfl aumann, u. & schulz, m. 2003: centennial-to-millennial-scale periodicities of holocene climate and sediment injections off the western barents shelf, 75° n. boreas 32, 447–461. schytt, v. 1981: ymer-80’s landbaserade naturegeografi ska forskning. (ymer 80’s land-based research in physical geography.) expedition ymer-80. ymer årsbok, 51–66. ślubowska, m. a., koç, n., rasmussen, t. l. & klitgaardkristensen, d. 2005: changes in the fl ow of atlantic water into the arctic ocean since the last deglaciation: evidence from the northern svalbard continental margin, 80° n. paleoceanography 20, pa4014. summerhayes, v. s. & elton, c. s. 1928: further contributions to the ecology of spitsbergen. j. ecol. 16, 193–268. svendsen, j. i. & mangerud, j. 1992: paleoclimatic inferences from glacial fl uctuations on svalbard during the last 20,000 years. clim. dyn. 6, 213–220. theisen, b. f. 1973: the growth of mytilus edulis l. (bivalvia) from disko and thule district, greenland. ophelia 12, 59–77. vibe, c. 1950: the marine mammals and the marine fauna in the thule district (northwest greenland) with observations on ice conditions in 1939–41. medd. grønl. 150(6). copenhagen: danish polar center. węsławski, j. m., zajączkowski, m., wiktor, j. & szymelfenig, m. 1997: intertidal zone of svalbard. 3. littoral of a subarctic, oceanic island. bjørnøya. polar biol. 15, 45–52. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice stable ringed seal (pusa hispida) demography despite significant habitat change in svalbard, norway research article stable ringed seal (pusa hispida) demography despite significant habitat change in svalbard, norway magnus andersen, kit m. kovacs & christian lydersen norwegian polar institute, fram centre, tromsø, norway abstract ringed seals, which are small phocid seals, range across the circumpolar arctic, and have evolved in close association with sea ice and depend on it for all aspects of their life history. this research study compares age structure, reproductive parameters, body size and condition during three time periods—1981–82 (n = 277), 2002–04 (n = 272) and 2012–18 (n = 212)—to study potential changes in demography in ringed seals in western svalbard, norway, an area that has undergone dramatic changes in sea-ice conditions during recent decades. age distributions for the three time periods were similar, with the exception that the most recent period had a higher proportion of young animals. age at sexual maturity for both sexes was similar for the two most recent periods, both being lower than in the 1980s. ovulation rates did not vary significantly among the three periods (range 0.86–0.94). pregnancy rates were only available for the most recent study period (0.71); this value falls within the range reported from other arctic regions. body length showed no clear temporal patterns; males were slightly longer in the most recent period, while females were slightly longer in the first period. data from may in all periods suggest that body condition has not varied significantly through time. in conclusion, although the ringed seal breeding habitat in svalbard has declined significantly in recent decades, demographic parameters appear to be largely unaffected. life-history plasticity in combination with a small-scale regional variation in environmental conditions might explain the lack of changes in demography over time. keywords climate change; sea ice; arctic ecosystem; recruitment; body growth; body condition abbreviations ci: confidence interval c-index: body condition index citation: polar research 2021, 40, 5391, http://dx.doi.org/10.33265/polar.v40.5391 copyright: polar research 2021. © 2021 m. andersen et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 29 april 2021 competing interests and funding: the authors report no conflict of interest. the svalbard environmental protection fund provided financial support in 2012 for a pilot project to collect biological samples from sport hunters and trappers and later supported harvest sampling (and aging) for the 2013 and 2014 hunting seasons. correspondence to: magnus andersen, norwegian polar institute, fram centre, po box 6606, no-9296, tromsø, norway. e-mail: magnus.andersen@npolar.no introduction ringed seals (pusa hispida) have evolved in close association with arctic sea ice and depend on it for virtually all aspects of their life history (smith & hammill 1981; smith et al. 1991; reeves 1998; kovacs et al. 2011). this high-arctic endemic seal begins its life on land-fast sea ice in fjords and along the coastlines of arctic waters, including those in svalbard in most areas where land-fast sea ice forms (lydersen & gjertz 1986; lydersen & ryg 1991; smith & lydersen 1991). some birthing also takes place in areas with drifting sea ice in some parts of the arctic, including the barents sea (finley et al. 1983; wiig et al. 1999), although land-fast ice appears to be a strongly favoured habitat for birthing and mating. ringed seal pups are born in snow caves (birth lairs) that are dug out in snow drifts on the sea ice above a breathing hole (smith & stirling 1975). the birth lair is essential for the survival of pups, which weigh only ca. 4 kg when they are born; it provides thermal protection and also some protection against polar bears (ursus maritimus), arctic foxes (vulpes lagopus) and other predators (smith 1980; gjertz & lydersen 1986a; lydersen & smith 1989). each mother has a series of lairs, and if the lair where her pup is resting is attacked, she will move it to another location (smith & stirling 1975; lydersen & hammill 1993). if there is not enough snow cover by late winter to build such a series of shelters, pup mortality levels are very high. ice stability is also important because ringed seals have the longest nursing period of any of the northern true seals (members of the family phocidae) and need stable ice throughout the period of maternal care, which lasts for about six weeks. warm spring temperatures or rain during the nursing period can result in the collapse of lairs, and hence, reproductive failure (stirling & smith 2004). ringed seals also use sea ice as a platform for their annual moult in the late spring, when they replace their hair coat and upper skin layers (carlens et al. 2006). moulting in the water is energetically costly and is much more stressful for the animals than when it occurs on sea ice where they can sunbathe and circulate the blood to the skin in the air (without the high heat loss that occurs in water [freitas, kovacs, ims, fedak et al. 2008]). ringed seals also depend on sea ice for resting at other times of year, close to food sources (freitas, kovacs, ims & lydersen 2008). they feed predominantly on ice-associated prey, including polar cod (boreogadus saida), arctic cod (arctogadus glacialis) and large arctic zooplankton species, such as parathemisto libellula, that are part of the sympagic ecosystem (gjertz & lydersen 1986b; wathne et al. 2000; labansen et al. 2011; bengtsson et al. 2020). ringed seals’ extreme affiliation with sea ice raises serious concerns over their future survival in a warming world (kovacs & lydersen 2008). dramatic reductions in sea ice have already been reported in recent decades in the arctic, and these declines are predicted to continue, and, in fact, to escalate in the decades to come (parkinson 2014; notz & stroeve 2016; overland et al. 2016). reductions in this unique habitat reflect a direct loss of habitat availability for ringed seals. climate change will also pose other risks to this arctic resident: reductions of their traditional lipid-rich prey due to shifts in arctic food webs stimulated by ice-cover declines and warmer water temperatures; greater risk of disease; more predation by killer whales (orcinus orca) in some regions; and increased human impacts from shipping, development and pollution in the north (laidre et al. 2008; kovacs et al. 2011; kovacs et al. 2012; caff 2013; laidre et al. 2015; vanwormer et al. 2019). declines in pup production, body condition and ovulation rates associated with changing ice conditions have been documented for ringed seals in the canadian arctic, where extensive hunt monitoring is undertaken (reeves 1998; harwood et al. 2000a, b; ferguson et al. 2017). a status review of ringed seals led to the listing of this species and bearded seals (erignathus barbatus) on the us endangered species list because a significant portion of their range is expected to be lost in the foreseeable future as a result of sea-ice loss (gill et al. 2011; gilg et al. 2012). similarly, the committee on the status of endangered wildlife in canada recommended that the canadian government list ringed seals as a species at risk under the category “special concern” in their species at risk act. furthermore, ringed seals have been selected as a key indicator species by conservation of arctic flora and fauna to assess the status of the arctic marine ecosystem (kovacs 2014). svalbard is a “hotspot” in the context of climate change. sea ice has declined markedly in the archipelago over the last three decades, with precipitous changes being observed since 2006 (e.g., laidre et al. 2015; muckenhuber et al. 2016), and temperature increases in this region in both the water and the air are well above the norm for the arctic (forland et al. 2011; isaksen et al. 2016). these changes affect the freeze-up and break-up of the land-fast ice, particularly along the west and north coast of spitsbergen, leading to a shorter sea-ice period and less snow accumulation on top of the ice. furthermore, modifications to the ecosystem are taking place as atlantic marine species are moving into the region. the current changes are undoubtedly having an impact on the ringed seal population, but there are few data regarding the effects that these ongoing changes are having on this species in this region in terms of population demography. ringed seals are difficult to survey, so it is common to evaluate biological parameters measured on hunted animals in order to determine changes in population parameters and to infer population trajectories from such data. ringed seals are harvested by sport hunters and a few trappers in svalbard. in the past, some research collections were carried out (lydersen & gjertz 1987; krafft, kovacs, ergon et al. 2006). the current ringed seal harvest in svalbard is small but biological data collected from locally hunted animals mainly along the west coast, in combination with earlier sampling programmes, provide a time series on demography of the population in the archipelago, which permits exploration of potential changes in vital parameters, growth rates or body conditions in relation to climate change over time. given the recent sea-ice habitat degradation for ringed seals in the barents sea region, we test the following hypotheses relative to three time periods: (1) recruitment declined because of low pup survival, (2) age at maturity increased because of slower body growth due to reductions in ice-associated prey, (3) reproductive rates decreased (i.e., lower ovulation and pregnancy rates), (4) body sizes decreased because of lower prey availability and (5) body conditions declined. materials and methods during 1981–82 (lydersen & gjertz 1987) and 2002–04 (krafft, kovacs, ergon et al. 2006), ringed seals were collected during scientific harvests in april–july, while local trappers and sport hunters collected animals in the period 2012–18 during the open hunting season march–october. all sampling was conducted in the fjords on the north and west side of spitsbergen, svalbard. the seals were shot on the sea ice in early spring or from small boats in the open-water period in summer and early autumn. when hunting took place in spring, mothers accompanied by pups were avoided. the data from the three periods are still comparable, as the same materials and measurements were collected, and similar field and laboratory procedures were followed. the months of sampling varied somewhat in different periods, and some seals were avoided during parts of the sampling; this has been taken into account in the analyses. for all seals, standard body length and axillary girth were measured to the nearest centimetre using standard methods (committee on marine mammals 1967). canine teeth from upper or lower jaws were sampled for age determination. from the males, intact pairs of testes were dissected out, and from the females, ovaries and the uterus were collected. the samples were stored frozen at −20°c. material available two hundred and twelve sets of samples were compiled at the norwegian polar institute from hunter takes during the years 2012–18. hunting was carried out from wijdefjorden and kongsfjorden in the north to van mijenfjorden in the south, with most animals being taken in st. jonsfjorden and isfjorden (fig. 1). some seals were harvested on the sea ice in the late winter and spring (march–june), but most hunting took place during the ice-free season (july–october). data sets for the periods 1981–82 and 2002–04 comprised data on 277 and 272 individuals, respectively, and the overall sampling area was similar to the 2012–18 harvest but included only the time period april–july (fig. 1). in all the three periods, some data were lacking for a few seals, so the number of individuals included in the various analyses is variable. fig. 1  map of svalbard showing the study area and places mentioned in the text (shaded areas represent land; white areas represent glaciers). age determination for age determination, jaws were boiled for 30 min before the canines were extracted. ages were read from the cementum layer of decalcified, stained longitudinal sections. these details were available for 208 individuals (109 male and 99 females) in 2012–18 (aging conducted by age dynamics, christina lockyer). data on age for the periods 1981–82 and 2002–04 were available for 275 (131 male and 144 female) and 272 (170 male and 102 female) individuals, respectively (lydersen & gjertz 1987; krafft, kovacs, ergon et al. 2006). reproduction age at sexual maturity was determined from materials collected in 2012–18, and the results were compared with data published for the periods 1981–82 and 2002–04. for the most recent data set, indirect evidence of sexual maturity in males were considered using sizes and growth patterns of testes (mclaren & smith 1985; ryg et al. 1991), which were available from 98 known-aged males. mass of testis, including epididymis, was measured to the nearest 0.1 g on a laboratory scale (sartorius bp 210 d). when both testes were available from the same individual, a mean value was used. the onset of maturity was considered to occur during an age interval with a sharp increase in testes growth, as confirmed by microscopy for similar samples by krafft, kovacs, ergon et al. (2006), who found all males with testes heavier than 10 g to be sexually mature. for evaluation of sexual maturity in females, ovaries and uteri were available for most of the animals. ovaries were sectioned (ca. 5 mm sections) and examined macroscopically for the presence of follicles: corpora lutea or corpora albicantia. if the ovary contained any of these bodies, the female was classified as sexually mature (mclaren & smith 1985). the uterus (when available) was also examined macroscopically, and if it showed signs of earlier pregnancies (i.e., significantly thicker tissue structure), this was also considered as a sign of sexual maturity. ovulation rates were determined as the proportion of females with a corpus luteum in an ovary per mature female; only samples containing both ovaries were included in the analysis. pregnancy rates were calculated as the proportion of females with a foetus per mature female in the months august–october, when macroscopic detection of a foetus was possible. body growth in order to allow comparison with previously published growth studies, body length growth in the ringed seals was described using the von bertalanffy growth curve (von bertalanffy 1957; schnute 1981): lx = l∞ (1−e a(x–x0))b, where lx is body length, l∞ is the asymptotic value corresponding to adult standard length, x is the age of the animal, x0 is an estimated constant for prenatal growth, and a and b are constants being fitted to the data by regression, where a determines the rate of approach to the asymptote and b determines the curvilinearity of this approach (mclaren 1993). the estimated value of x0 used here is 0.61, according to mclaren (1993). it represents the time before birth at which the embryo starts growing after the period of delayed implantation. mclaren (1993) stated that when data on length or mass from young age classes, including pups, are scarce, which is true for this study, using the estimated x0 value serves to anchor the growth curve at its lower end. growth functions were fitted using the vbstarts-function in the fsa-package (http://www.rforge.net/fsa) and the nls-function in r version 4.0.3 (r core team 2014). data on the analysis of age-related length growth were available for n = 275 in 1981–82 (131 males and 144 females), n = 272 in 2002–04 (170 males and 102 females) and n = 207 in 2012–18 (109 males and 98 females). the asymptotic values and the parameter estimates are given with 95% cis in the nls-function output. boxplots (with all data points plotted) are presented to visualize the data for the three sampling periods for both sexes. the effect of sampling period on body length was further tested by linear regression (function lm, r version 4.0.3) using data for fully grown individuals (≥8 years). values of p and f are given, model estimates and corresponding cis (function confint, r) are presented, and statistically significant relationships are denoted. body condition variations in body condition by both month and time period were analysed using c-index, an index of body condition based on morphometric measurements (committee on marine mammals 1967): c-index = (ag × 100) sl-1, where ag is axillary girth and sl standard body length. c-index data were available from 132 males and 144 females in 1981–82, 173 males and 103 females in 2002–04, and 93 males and 92 females in 2012–18. for analyses of between-period trends, only data from march to july were included. boxplots are presented to visualize the data, and the effect of sampling period on body condition was tested by linear regression (function lm, r version 4.0.13). for 2012–18, data were also available for august, september and october, thus enabling an analysis of seasonal patterns. the effect of month on c-index values was analysed by linear regression (function lm, r version 4.0.3), and a boxplot with all data points plotted is given for visualization of the data. for the linear regressions, p values and f values are given, model estimates with corresponding cis are presented and statistically significant relationships are denoted. results age distribution during 2012–18, ages of ringed seals in the hunt varied from 0 to 33, with the oldest male being 26 years and the oldest female being 33 years); median age was nine years. the oldest animals during the periods 1981–82 and 2002–04 were 45 and 30 years old, and median ages were 12 and 10 years, respectively. young animals 0–3 years of age constituted 25.0% in the 2012–18 sample. in comparison, 0–3-year olds constituted 13 and 13.5% of the samples for the periods 1981–82 and 2002–04, respectively (fig. 2). a slow, decreasing trend in the number of animals is observed from the youngest age groups up to 20–25 years, followed by a sharp decline thereafter in all the three periods (fig. 2). fig. 2  frequency of age classes in svalbard ringed seals sampled in 1981–82, 2002–04 and 2012–18 (sexes combined). reproduction the age-related growth pattern of testes during 2012–18 (fig. 3) was similar to that seen in the period 2002–04 (see krafft, kovacs, ergon et al. 2006), indicating that age at maturity was attained from three to six years for males. lydersen & gjertz (1987) reported age at maturity for males to be between five and eight years during 1981–82 (table 1). reproductive organs were available for 100 females for 2012–18, and the maturity status could be determined for 94 of these animals. age data were available for 92 individuals, of which 74 were mature. in 2012–18, females reached sexual maturity starting at an age of three. fifty percent of three-year olds were mature, while 100% of the four-year olds were mature. similar analyses concluded that females matured between three and six years of age in 1981–82 and between two and four years of age in 2002–04. determination of the presence or absence of a corpus luteum was possible for 67 mature individuals in 2012–18, 63/67 had ovulated, so the ovulation rate (fcl/fmature) was 0.94. comparable rates were 0.91 for 1981–82 and 0.86 for 2002–04. fifty-two mature female seals were collected from august to october in 2012–18, of which 37 had a foetus. the pregnancy rate was, therefore, 0.71 (table 1). ages of the females bearing foetuses ranged from four to 28 years.   table 1 age at sexual maturity in males and females, ovulation and pregancy rates for ringed seals in svalbard in three time periods. time period male age at maturitya female age at maturityb ovulation rate fcl/fmature pregnancy rate ffetus/fmature 1981–82 5–8 3–6 0.91 – 2002–04 3–6 2–4 0.86 – 2012–18 3–6 3–4 0.94 71% (37/52) asexual maturity of males was assessed by testes size or the presence of sperm cells in the testis. bsexual maturity in females was confirmed by follicles, corpora lutea or corpora albicantia, in the ovaries. the uterus was also examined macroscopically for signs of earlier pregnancies. fig. 3  testis mass as an indication of the onset of sexual maturity in male ringed seals in svalbard during 2012–18. growth von berthalanffy growth curve parameters revealed quite similar growth patterns between sexes and periods, except for males in 2012–18 being longer than females (table 2, fig. 4). linear regression analyses further showed that the body length of adult animals (at least eight years of age) over the three collection periods differed somewhat for both males (f (2, 234) = 10.7, p < 0.05) and females (f(2, 245) = 7.9, p < 0.05; fig. 5, table 3), although low f values indicated weak patterns. while males were slightly longer in the most recent sample (2012–18: 134.4 cm, ci = 129.4, 139.3) compared with both the earlier periods (1981–82: 129.1 cm, ci = 127.2, 131.0; 2002–04: 127.4 cm, ci = 122.9, 131.9), females were slightly longer in the oldest sample (1981–82: 130.5 cm, ci = 128.8, 132.2) relative to the two more recent data sets (2002–04: 125.5 cm, ci = 121.2, 129.8; 2012–18: 126.9 cm, ci = 122.5, 131.3) (fig. 5, tables 2, 3).   table 2 von bertalanffy growth function parameter estimates for ringed seal length–age data collected during three periods (1981–82, 2002–04 and 2012–18) in svalbard. growth functions were fitted using the vbfuns-function in the fsa package (http://www.rforge.net/fsa/installfsa.r) for r (r version 4.0.3). growth parameter n parameter estimates l∞ a b male length, 1981–82 131 129.39 ± 1.08 0.44 ± 0.06 −2.10 ± 0.46 female length, 1981–82 144 131.35 ± 1.12 0.27 ± 0.04 −3.80 ± 0.79 male length, 2002–04 170 127.42 ± 0.81 0.49 ± 0.07 −1.82 ± 0.51 female length, 2002–04 102 126.30 ± 1.23 0.29 ± 0.07 −4.38 ± 1.50 male length, 2012–18 109 136.75 ± 1.89 0.24 ± 0.04 −4.43 ± 0.76 female length, 2012–18 98 127.77 ± 1.31 0.29 ± 0.07 −4.46 ± 1.28   table 3 model estimates with cis for linear regression analyses of ringed seal length for three sampling periods (1981–82, 2002–04, 2012–18), showing between-period differences in length for both sexes. between periods male length difference (cm) with ci female length difference (cm) with ci 1981–82 vs. 2002–04 −1.7 (−4.3, 1.0) −5.0 (−7.6, −2.4)a 1981–82 vs. 2012–18 5.3 (2.2, 8.4)a −3.6 (−6.3, −0.9)a 2002–04 vs. 2012–18 6.9 (4.0, 9.9)a 1.4 (−1.50, 4.3) astatistically significant difference at the p = 0.05 level. fig. 4  von bertalanffy growth function describing standard length versus age (truncated at 30 years) for male and female ringed seals sampled in svalbard during 1981–82, 2002–04 and 2012–18. fig. 5  standard length of adult male and female ringed seals (eight years of age and older) collected during three time periods (1981–82, 2002–04 and 2012–18) in svalbard. linear regression analyses showed that body length of adult animals (8+ years of age) over the three collection periods differed somewhat for both males (f (2, 234) = 10.7, p < 0.05) and females (f (2, 245) = 7.9, p < 0.05. while males were slightly longer in the most recent sample compared with both the earlier periods, females were slightly longer in the oldest sample relative to the most recent data. body condition males in 2004–05 had higher c-index values (80.3, ci = 78.0, 82.6) compared to those in 1981–82 (76.5, ci = 75.5, 77.5) and 2012–18 (72.6, ci = 74.5, 80.8) (f(2, 337) = 16.04, p < 0.05), but low f values indicated weak patterns. for females, there were no effect of sampling period on c-index (1981–2002: 80.3, ci = 79.1–81.5; 2002–04: 81.3, ci = 78.2, 84.4; 2012–18: 79.6, ci = 75.4, 83.8) (f (2, 273) = 0.8, p = 0.44) (fig. 6, table 4). when considering the data set for the period 2012–18, which includes data from march to october, significant differences in condition were seen seasonally (f (7, 177) = 6.9, p < 0.05), with c-index values being lowest in june and highest in the autumn (august–october; fig. 7).   table 4 model estimates with cis for linear regression analyses of ringed seal c-index for three sampling periods (1981–82, 2002–04, 2012–18), showing between-period differences in c-index for both sexes. between periods male c-index difference with ci female c-index difference with ci 1981–82 vs. 2002–04 3.75 (2.43, 5.07)a 0.98 (−0.89, 2.87) 1981–82 vs. 2012–18 1.11 (−1.06, 3.29) −0.69 (−3.66, 2.28) 2002–04 vs. 2012–18 −2.64 (−4.76, −0.52)a −1.68 (−4.74, 1.39) astatistically significant difference at the p = 0.05 level. fig. 6  a comparison of estimated body condition of male and female ringed seals harvested in svalbard during the three time periods (1981–82, 2002–04 and 2012–18). linear regression analysis showed that males in 2004–05 had higher c-index values compared with 1981–82 and 2012–18 (f(2, 337) = 16.04, p < 0.05), while for females there were no effects of sampling period on the c-index (f(2, 273) = 0.8, p = 0.44). fig. 7  seasonal pattern in body condition (males and females combined) for ringed seals in svalbard, 2012–18. linear regression analysis showed significant differences in condition seasonally (f(7, 177) = 6.9, p < 0.05), with c-index values being lowest in june and highest in the autumn (august–october). discussion dramatic environmental changes have been taking place in the marine environment in the svalbard archipelago and the broader barents sea region (eriksen & dalpadado 2011; buchholz et al. 2012; fossheim et al. 2015; laidre et al. 2015; eriksen et al. 2017; lind et al. 2018). sea ice has declined in svalbard over the last three decades (e.g., laidre et al. 2015; muckenhuber et al. 2016), as temperatures in the water and the air have increased in the region (forland et al. 2011; isaksen et al. 2016). this has affected the timing of the freeze-up and break-up of the land-fast ice, with shorter sea-ice periods and less snow accumulation on the ice. however, despite the significant changes to the marine system in svalbard fjords, including an “atlantification” of the fish and invertebrate communities and dramatic declines in sea ice, ringed seals seem to have been able to accommodate the changes, such that their demographic parameters have remained largely unchanged. the youngest age classes of ringed seals are typically most numerous in hunts, as is the case generally for phocid seals (mclaren 1958; smith 1973, 1987; chambellant et al. 2012). this is due to the fact that naïve animals are easier to harvest because they are less wary, and young animals are proportionally more numerous (smith 1973, 1987; reeves 1998). furthermore, young seals feed in shallower waters closer to shore, where hunting typically takes place during the open-water season, and therefore, are more easily taken by hunters. the expectation, in this study, was that few young animals would be available for harvest in the 2012–18 sample, as opportunistic field observations (authors and jon aars, pers. com.) suggested, reproduction was believed to be negligible in recent years along the west coast of spitsbergen, svalbard. the most recent data set cannot be directly compared with the two previous ones for which animals were collected during the spring and young animals seen with their mothers were avoided. nevertheless, in the 2012–18 harvest, there was a higher proportion of individuals three years of age or younger than in the earlier periods. the way the harvest and scientific sampling has been conducted has certainly affected the age distribution of the various sampling periods. most of the hunting during the periods 1981–82 and 2002–04 was conducted on land-fast ice in fjords along the west coast of spitsbergen in the early spring. during this time, some females were still accompanied by their pups, and these individuals were avoided, inducing a bias (low number of pups in the samples). krafft et al. (2007) showed that juvenile seals were pushed towards the outer parts of the fjords, and as hunting was often conducted on the most stable ice deep inside the fjords late in the spring season, the younger age classes would be under-represented (mclaren 1958; smith 1973; lydersen & gjertz 1987). in the 2012–18 period, most hunting took place during the open water season, and capture probability would be more equal between different age groups, thereby naturally leading to more young animals in the harvest (mclaren 1958; smith 1973; lydersen & gjertz 1987). the proportion of young animals in harvest samples has frequently been used as a measure of reproductive success in ringed seals, and large spatial and temporal variations have been reported in previous studies. some of the variance has been attributed to actual variation in population demographical processes, but sampling biases have also been noted as challenges for interpreting the data (smith 1973, 1987; kingsley & byers 1998; teilmann & kapel 1998; chambellant et al. 2012). the number of young animals in svalbard currently is low compared with some studies that report 30–40% young-of-the-year pups in the harvest, but higher than others who report fewer than 5% young-of-the-year pups (mclaren 1958; smith 1973, 1987; stirling & lunn 1997; chambellant et al. 2012). although no scientific data have been collected on survivorship for ringed seals in svalbard, opportunistic observations during spring research activities in the polar bear and sea-ice programmes suggest very high mortalities of ringed seal pups in recent springs (jon aars, pers. com.). additionally, the seals that have been visible on the spring sea ice have been concentrated in the small areas of available sea ice, and little snow cover on the ice, because of the short ice season, has left ringed seal pups very much exposed to predators (jon aars, pers. com.; lydersen & smith 1989). stirling (2005) found young-of-the-year ringed seals in low proportions in hudson bay in the 1990s and suggested this was due to a long-term shift in reproduction caused by changes in the sea-ice system in that region. for the same population and time period, ferguson et al. (2005) confirmed that low snow depth was the main driver for reducing the ringed seal recruitment, and early break-up of sea ice in spring also had negative effects. reimer et al. (2019) coupled a demographic model to emerging environmental stressors for ringed seals in the amundsen gulf and prince albert sound, canada, and their projections up to year 2100 suggested declines of population size from 50 to 99%. the main driver of the declines was lower proportions of juveniles compared with adults in the studied population. young animals (0–3 years of age) in the 2012–18 svalbard sample accounted for 25% of the population, which is at the low end of the normal range for ringed seals (smith 1973, 1987; kingsley & byers 1998; teilmann & kapel 1998; chambellant et al. 2012). our initial hypothesis was that little reproduction was taking place in the study area, but clearly some recruitment is occurring. one of the explanations might be that young animals are moving onto the west coast from the east, where sea-ice conditions remain better. alternatively, there might be local production in the area where hunting has taken place, in the sill fjords that occur on the north side of isfjorden, which retain ice for much longer periods in the spring than most west coast fjord systems, creating a spatially limited, but successful habitat for ringed seal reproduction. phocid seals usually reach sexual maturity when they have grown to ca. 80–90% of their final body size (laws 1956). thus, there is some flexibility in the age when they are first able to reproduce depending on how fast they grow, which, in turn, depends mainly on food availability. krafft, kovacs, ergon et al. (2006) found that the age of first maturity for ringed seals in svalbard dropped between the 1980s and the early part of this century, reaching a minimum for this species at 3.8 years of age in the early 2000s. they suggested that this was either due to fewer seals competing for food or greater availability of prey resources for this population. given the small hunt in svalbard and the good ice conditions (i.e., good breeding habitat conditions) prior to the scientific harvest in 2002–04, the drop in age at sexual maturity was likely due to abundant food resources. seals were in good physical condition; ovulation rates were generally high and comparable with similar studies elsewhere in the arctic (ferguson et al. 2005; stirling 2005). krafft, kovacs, ergon et al. (2006) further suggested that the decrease in age at maturity from 1981–82 (lydersen & gjertz 1986) to 2002–04 data could be a result of the increasing polar bear population putting higher predation pressure on ringed seals. however, reduced sea ice, in more recent times, might be making it more difficult for polar bears to hunt ringed seals in the late spring and summer, releasing some of the pressure that would otherwise fall on ringed seals from svalbard’s increasing polar bear population (hamilton et al. 2017). the results of this study show that maturity has not changed in recent decades, refuting our hypothesis that the observed habitat change has had a great impact on this parameter. reduced predation success by polar bears on ringed seals in summer and fall in low-ice conditions might be affording adult seals some predator relief (hamilton et al. 2017). ringed seal reproductive rates have been studied in many parts of the arctic, often in harvested populations where large sample sizes are available (e.g., harwood et al. 2012). various parameters have been used to assess reproductive outputs, including the proportion of mature females in the population, which are pregnant or lactating or have ovulated (presence of a corpus luteum) (mclaren 1958; reeves 1998). rates vary greatly in both space and time, confirming this species’ sensitivity to environmental or ecological processes and conditions when it comes to reproduction (holst et al. 1999; iacozza & ferguson 2014). values have been reported from 0.45 for the barrow strait in the mid-1980s (hammill 1987) to 0.91 in svalbard in 1981–82 (lydersen & gjertz 1986). the 0.94 ovulation rate reported in this study during the period 2012–18 is at the high end of the scale for this parameter. while the term “reproductive rate” includes several types of data describing reproductive potential, pregnancy rate is the ideal parameter for assessing recruitment potential. ringed seals mate in the late spring, but the fertilized egg does not implant in the uterine wall until approximately four months later, making pregnancy difficult to detect before the autumn. while high ovulation rates are often seen in seals, pregnancy rates are often considerably lower. fifty-two female seals collected during the fall in the 2012–18 time period, in this study, were sexually mature; 71% of these were pregnant, a value in the middle of the range of rates reported for ringed seals in other regions and time periods in the arctic (reeves 1998; harwood et al. 2000a, b; ferguson et al. 2017). body size versus age in the most recent sample is similar to early periods, suggesting that there have been no dramatic changes in this biological parameter recently in svalbard. while males were longer in the most recent sample compared with both the earlier samples, females were slightly longer in the oldest sampling period relative to the most recent data. the data herein further suggest that ringed seals from this population are comparable in size with other populations across the arctic (holst & stirling 2002; ferguson et al. 2018). the current population size and trend are unknown for ringed seals in svalbard. the most recent surveys were conducted in 2002 and 2003, when krafft, kovacs, frie et al. (2006) estimated some 7585 (95% ci: 6332–9085) ringed seals in 18 fjords along the west and north coasts of spitsbergen. the only previous estimate was a crude extrapolation based on the estimated pup production. in the study by smith & lydersen (1991), the production of ringed seal pup in the svalbard area was estimated to be 8000 individuals based on the sea-ice type, distribution and birth lair densities. using a modelled relationship for pup production versus population size constructed for harp seals (ices 2004), this would represent a total population of about 40 000 individuals. the differences in methodology, as well as areas covered in the estimates, make these two studies incomparable in terms of trend assessment. little is known regarding site fidelity levels in ringed seals, although adult animals are primarily year-round residents of very small home ranges in svalbard (hamilton et al. 2016; hamilton et al. 2019). subadult animals from this population undertake long-range movements in summer and sometimes shift from one coast to the other in svalbard (freitas, kovacs, ims, fedak et al. 2008; hamilton et al. 2015, 2016). there could, therefore, be influxes of young animals between areas, with pup production (and survival) on the east coast serving as a reservoir, which might be supporting the demographic patterns of this study documented in the western parts of svalbard. alternatively, though less likely, local production could be greater than currently thought in the hunted area. there are certainly marked differences from fjord to fjord in svalbard in the prevalence of different water masses (atlantic water versus arctic water), water temperature and wind exposure, and hence, in the probability that ice will form in winter and remain stable through the spring. “sill” or “threshold” fjords tend to be sheltered from influxes of atlantic water and are more sheltered from the effects of wave action, and hence, retain sea ice. there are several such fjords in the principle hunting areas for ringed seals in svalbard, including van mijenfjorden (especially the inner van mijenfjorden–rindersbukta area) and in the northern parts of isfjorden (billefjorden and tempelfjorden). body condition of ringed seals has not declined recently, contrary to what we had predicted, despite the fact that the arctic prey that this species depends upon are likely in decline (fossheim et al. 2015; skaret et al. 2018). diet of ringed seals in svalbard is dominated by polar cod (boreogadus saida), prickleback (stichaeidae spp.), species in the sculpin families (cottidae spp.) and ice-associated amphipods (gjertz & lydersen 1986b; wathne et al. 2000; labansen et al. 2007; labansen et al. 2011; bengtsson et al. 2020). atlantic species, such as herring (clupea harengus), blue whiting (micromesistius poutassou) and krill (thysanoessa sp.), appear to be increasing slightly in the diet, but polar cod is still dominant (bengtsson et al. 2020). lowther et al. (2017) suggested that a dietary shift might have taken place over the last few decades based on stable isotope analyses, but the changes observed could represent changes in the diet of prey species. some female ringed seals, in particular, harvested in the late summer and early fall, in the current study, had extremely high c-indexes. the reason might be that loss of pups early in the nursing period leads to a significantly lower energetic expenditure on lactation (lydersen & kovacs 1999). adult females repeatedly failing to go through the full nursing period will result in them retaining their blubber layer thickness. harvest material from a population with a large number of such females may indicate that the population is doing well, while the truth may be the opposite, as the survival rates of pups are low. a seasonal increase in condition from the spring until the fall was observed in the 2012–18 data, as expected and previously described (smith & hammill 1981; ryg, lydersen et al. 1990; ryg, smith et al. 1990; young & ferguson 2013; bengtsson et al. 2020). in conclusion, demographic data spanning almost four decades suggest that ringed seals in svalbard have relatively stable body growth rates and good body condition (and hence are finding sufficient prey). however, the production, or survival, of young animals is somewhat low, as proportions of juvenile-age classes are not as high as would be expected in a stable population. additionally, pregnancy rates are at the low end of the range for this species. low pup survival is not unexpected, given that there has been a period from 2006 until the present with a markedly reduced ice cover in west coast fjords. even in years when the ice extent is quite large in this period, the ice has started to form later than normal, and hence, has insufficient snow depth for optimal ringed seal breeding conditions. however, although ringed seals in svalbard have experienced significant changes in their habitat over the last 30 years, demographic parameters appear to be largely unaffected. life-history plasticity, in combination with a small-scale regional variation in conditions, might explain the lack of clear patterns of change in demography over time. monitoring the ringed seals in svalbard should be continued to gain further insights into possible changes in age structure, body condition and life-history parameters during this time of marked environmental changes. these analyses should be supplemented by additional monitoring to study potential dietary shifts and regional patterns of change within different fjords in svalbard. the pronounced contrast in the rate of environmental changes in west coast versus east coast fjords could provide considerable insights into responses of ringed seals to climate change and the overall status of this species in svalbard. although logistically challenging, more comprehensive monitoring of this species is required to understand the effects of climate change on this population of ringed seals. acknowledgements the authors thank the environmental specimen bank of norway (https://miljoprovebanken.no/english), which has supported the collection of samples since 2015. references bengtsson o., lydersen c., kovacs k.m. & lindström u. 2020. ringed seal (pusa hispida) diet on the west coast of spitsbergen, svalbard, norway: during a time of ecosystem change. polar biology 43, 773–788, doi: 10.1007/s00300-020-02684-5. buchholz f., werner t. & buchholz c. 2012. first observation of krill spawning in the high arctic kongsfjorden, west spitsbergen. polar biology 35, 1273–1279, doi: 10.1007/s00300-012-1186-3. caff 2013. arctic biodiversity assessment. status and trends in arctic biodiversity. akureyri: conservation of arctic flora and fauna. carlens h., lydersen c., krafft b.a. & kovacs k.m. 2006. spring haul-out behavior of ringed seals (pusa hispida) in kongsfjorden, svalbard. marine mammal science 22, 379–393, doi: 10.1111/j.1748-7692.2006.00034.x. chambellant m., stirling i., gough w.a. & ferguson s.h. 2012. temporal variations in hudson bay ringed seal (phoca hispida) life-history parameters in relation to environment. journal of mammalogy 93, 267–281, doi: 10.1644/10-mamm-a-253.1. committee on marine mammals 1967. standard measurements of seals. journal of mammalogy 48, 459–462, doi: 10.2307/1377778. eriksen e. & dalpadado p. 2011. long-term changes in krill biomass and distribution in the barents sea: are the changes mainly related to capelin stock size and temperature conditions? polar biology 34, 1399–1409, doi: 10.1007/s00300-011-0995-0. eriksen e., skjoldal h.r., gjøsæter h. & primicerio r. 2017. spatial and temporal changes in the barents sea pelagic compartment during the recent warming. progress in oceanography 151, 206–226, doi: 10.1016/j.pocean.2016.12.009. ferguson s.h., stirling i. & mcloughlin p. 2005. climate change and ringed seal (phoca hispida) recruitment in western hudson bay. marine mammal science 21, 121–135, doi: 10.1111/j.1748-7692.2005.tb01212.x. ferguson s.h., young b.g., yurkowski d.j., anderson r., willing c. & nielsen o. 2017. demographic, ecological and physiological responses of ringed seals to an abrupt decline in sea ice availability. peerj 5, e2957, doi: 10.7717/peerj.2957. ferguson s.h., zhu x., young b.g., yurkowski d.j., thiemann g.w., fisk a.t. & muir d.c.g. 2018. geographic variation in ringed seal (pusa hispida) growth rate and body size. canadian journal of zoology 96, 649–659, doi: 10.1139/cjz-2017-0213. finley k.j., miller g.w., davi r.a. & koski w.r. 1983. a distinctive large breeding population of ringed seals (phoca hispida) inhabiting the baffin bay pack ice. arctic 36, 162–173, doi: 10.14430/arctic2259. forland e.j., benstad r., hanssen-bauer i., haugen j.e. & skaugen t.e. 2011. temperature and precipitation development at svalbard 1900–2100. advances in meteorology 2011, article no. 893790, doi: 10.1155/2011/893790. fossheim m., primicerio r., johannesen e., ingvaldsen r.b., aschan m. & dolgov v. 2015. recent warming leads to a rapid borealization of fish communities in the arctic. nature climate change 5, 673–677, doi: 10.1038/nclimate2647. freitas c., kovacs k.m., ims r.a., fedak m.a. & lydersen c. 2008. ringed seal post-moulting movement tactics and habitat selection. oecologia 155, 193–204, doi: 10.1007/s00442-007-0894-9. freitas c., kovacs k.m., ims r.a. & lydersen c. 2008. predicting habitat use by ringed seals (phoca hispida) in a warming arctic. ecological modelling 217, 19–32, doi: 10.1016/j.ecolmodel.2008.05.014. gilg o., kovacs k.m., aars j., fort j., gauthier g., gramillet d., ims r.a., meltofte h., moreau j., pos e., schmidt n.m., yannic g. & bollache l. 2012. climate change and the ecology and evolution of arctic vertebrates. annals of the new york academy of sciences 1249, 166–190, doi: 10.1016/j.ecolmodel.2008.05.014. gill m.j., crane k., hindrum r., arneberg p., bysveen i., denisenko n.v., gofman v., grant-friedman a., gudmundsson g., hopcroft r.r., iken k., labansen a., liubina o.s., melnikov i.a., moore s.e., reist j.d., sirenko b.i., stow j., ugarte f., vongraven d. & watkins j. 2011. arctic marine biodiversity monitoring plan (cbmp-marine plan). caff monitoring series report 3. akureyri: conservation of arctic flora and fauna. gjertz i. & lydersen c. 1986a. polar bear predation on ringed seals in the fast-ice of hornsund, svalbard. polar research 4, 65–68, doi: 10.3402/polar.v4i1.6921. gjertz i. & lydersen c. 1986b. the ringed seal (phoca hispida) spring diet in northwestern spitsbergen, svalbard. polar research 4, 53–56, doi: 10.1111/j.1751-8369.1986.tb00518.x. hamilton c.d., kovacs k.m., ims r.a., aars j. & lydersen c. 2017. an arctic predator–prey system in flux: climate change impacts on coastal space use by polar bears and ringed seals. journal of animal ecology 86, 1054–1064, doi: 10.1111/1365-2656.12685. hamilton c.d., kovacs k.m. & lydersen c. 2019. sympatric use of a glacial fjord by two arctic endemic seals. marine ecology progress series 615, 205–220, doi: 10.3354/meps12917. hamilton c.d., lydersen c., ims r.a. & kovacs k.m. 2015. predictions replaced by facts: a keystone species’ behavioural responses to declining arctic sea-ice. biology letters 11, 1–6, doi: 10.1098/rsbl.2015.0803. hamilton c.d., lydersen c., ims r.a. & kovacs k.m. 2016. coastal habitat use by ringed seals pusa hispida following a regional sea-ice collapse: importance of glacial refugia in a changing arctic. marine ecology progress series 545, 261–277, doi: 10.3354/meps11598. hammill m.o. 1987. ecology of ringed seal (phoca hispida schreber) in the fast-ice of barrow strait, northwest territories. phd thesis, macdonald college of mcgill university, montreal. harwood l.a., smith t.g. & melling h. 2000a. reproduction and body condition of the ringed seal (phoca hispida) in the eastern beaufort sea, nt, canada, as assessed through a harvest-based sampling program. arctic 53, 422–431. harwood l.a., smith t.g. & melling h. 2000b. variation in reproduction and body condition of the ringed seal (phoca hispida) in western prince albert sound, nt, canada, as assessed through a harvest-based sampling program. arctic 53, 422–431, doi: 10.14430/arctic872. harwood l.a., smith t.g., melling h., alikamik j. & kingsley m.c.s. 2012. ringed seals and sea ice in canada’s western arctic: harvest-based monitoring 1992–2011. arctic 65, 377–390, doi: 10.14430/arctic4236. holst m., stirling i. & calvert w. 1999. age structure and reproductive rates of ringed seals (phoca hispida) on the northwestern coast of hudson bay in 1991 and 1992. marine mammal science 15, 1357–1364, doi: 10.1111/j.1748-7692.1999.tb00898.x. holst m. & stirling i. 2002. a comparison of ringed seal (phoca hispida) biology on the east and west sides of the north water polynya, baffin bay. aquatic mammals 28, 221–230, doi: 10.1111/j.1748-7692.2001.tb01304.x. iacozza j. & ferguson s.h. 2014. spatio-temporal variability of snow over sea ice in western hudson bay, with reference to ringed seal pup survival. polar biology 37, 817–832, doi: 10.1007/s00300-014-1484-z. ices 2004. report of the ices/nafo working group on harp and hooded seals. ices cm 2004/acfm: 6. 2–6 september 2003. arkhangelsk russia. copenhagen: international council for the exploration of the seas. isaksen k., nordli o., forland e.j., lupikasza e., eastwood s. & niedzwiedz t. 2016. recent warming on spitsbergen—-influence of atmospheric circulation and sea ice cover. journal of geophysical research—atmospheres 121, 11913–11931, doi: 10.1002/2016jd025606. kingsley m.c.s. & byers t.j. 1998. failure in reproduction in ringed seals (phoca hispida) in amundsen gulf, northwest territories in 1984–1987. in m.p. heide-jorgensen & c. lydersen (eds.): ringed seals in the north atlantic. nammco scientific publications 1, 197–210. kovacs k.m. 2014. circumpolar ringed seal (pusa hispida) monitoring: caff’s ringed seal monitoring network. norwegian polar institute report series 143. tromsø: norwegian polar institute. kovacs k.m., aguilar a., aurioles d., burkanov v., campagna c., gales n., gelatt t., goldsworthy s., goodman s.j., hofmeyr g.j.g., härkönen t., lowry l., lydersen c., schipper j., sipilä t., southwell c., stuart s., thompson d. & trillmich f. 2012. global threats to pinnipeds. marine mammal science 28, 414–536, doi: 10.1111/j.1748-7692.2011.00479.x. kovacs k.m. & lydersen c. 2008. climate change impacts on seals and whales in the north atlantic arctic and adjacent shelf seas. science progress 91, 117–150, doi: 10.3184/003685008x324010. kovacs k.m., lydersen c., overland j.e. & moore s.e. 2011. impacts of changing sea-ice conditions on arctic marine mammals. marine biodiversity 41, 181–194, doi: 10.1007/s12526-010-0061-0. krafft b.a., kovacs k.m., ergon t., andersen m., aars j., haug t. & lydersen c. 2006. abundance of ringed seals (pusa hispida) in the fjords of spitsbergen, svalbard, during the peak molting period. marine mammal science 22, 394–412, doi: 10.1111/j.1748-7692.2006.00035.x. krafft b.a., kovacs k.m., frie a.k., haug t. & lydersen c. 2006. growth and population parameters of ringed seals (pusa hispida) from svalbard, norway, 2002–2004. ices journal of marine science 63, 1136–1144, doi: 10.1016/j.icesjms.2006.04.001. krafft b.a., kovacs k.m. & lydersen c. 2007. distribution of sex and age groups of ringed seals (pusa hispida) in the fast-ice breeding habitat of kongsfjorden, svalbard. marine ecology progress series 335, 199–206, doi:10.3354/meps335199. labansen a.l, lydersen c., haug t. & kovacs k.m. 2007. spring diet of ringed seals (phoca hispida) from northwestern spitsbergen, norway. ices journal of marine science 64, 1246–1256, doi: 10.1093/icesjms/fsm090. labansen a.l., lydersen c., levermann n., haug t. & kovacs k.m. 2011. diet of ringed seals (pusa hispida) from northeast greenland. polar biology 34, 227–234, doi: 10.1007/s00300-010-0874-0. laidre k.l., stern h., kovacs k.m., lowry l., moore s.e., regehr e.v., ferguson s.h., wiig ø., boveng p., angliss r.p., born e.w., litovka d., quakenbush l., lydersen c., vongraven d. & ugarte f. 2015. arctic marine mammal population status, sea ice habitat loss, and conservation recommendations for the 21st century. conservation biology 29, 724–737, doi: 10.1111/cobi.12474. laidre k.l., stirling i., lowry l.f., wiig ø., heide-jørgensen m.p. & ferguson s.h. 2008. quantifying the sensitivity of arctic marine mammals to climate-induced habitat change. ecological applications 18, 97–125, doi: 10.1890/06-0546.1. laws r.m. 1956. growth and sexual maturity in aquatic mammals. nature 4526, 193–194, doi: 10.1038/178193a0. lind s., ingvaldsen b. & furevik t. 2018. arctic warming hotspot in the northern barents sea linked to declining sea-ice import. nature climate change 8, 634–639, doi: 10.1038/s41558-018-0205-y. lowther a.d., fisk a., kovacs k.m. & lydersen c. 2017. interdecadal changes in the marine food web along the west spitsbergen coast detected in the stable isotope composition of ringed seal (pusa hispida) whiskers. polar biology 40, 2027–2033, doi: 10.1007/s00300-017-2122-3. lydersen c. & gjertz i. 1986. studies of the ringed seal (phoca hispida) in its breeding habitat in kongsfjorden, svalbard. polar research 4, 57–63, doi: 10.3402/polar.v4i1.6920. lydersen c. & gjertz i. 1987. population parameters of ringed seals (phoca hispida) in the svalbard area. canadian journal of zoology 65, 1021–1027, doi: 10.1139/z87-162. lydersen c. & hammill m. 1993. diving in ringed seal (phoca hispida) pups during the nursing period. canadian journal of zoology 71, 991-996, doi: 10.1139/z93-131. lydersen c. & kovacs k.m. 1999. behaviour and energetics of ice-breeding, north atlantic phocid seals during the lactation period. marine ecology progress series 187, 265–281, doi: 10.3354/meps187265. lydersen c. & ryg m. 1991. evaluating breeding habitat and estimating the size of a local population of ringed seal (phoca hispida) in svalbard, norway. polar record 27, 223–228, doi: 10.1111/j.1748-7692.2006.00035.x. lydersen c. & smith t.g. 1989. avian predation on ringed seal phoca hispida pups. polar biology 9, 489–490, doi: 10.1007/bf00261031. mclaren i.a. 1958. the biology of the ringed seal (phoca hispida schreher) in the eastern canadian arctic. fisheries research board canada 118, 1–97, doi: 10.1002/eap.1855. mclaren i.a. 1993. growth in pinnipeds. biological reviews 68, 1–79, doi: 10.1111/j.1469-185x.1993.tb00731.x. mclaren i.a. & smith t.g. 1985. population ecology of seals: retrospective and prospective views. marine mammal science 1, 54–83, doi: 10.1111/j.1748-7692.1985.tb00531.x. muckenhuber s., nilsen f., korosov a. & sandven s. 2016. sea ice cover in isfjorden and hornsund, svalbard (2000–2014) from remote sensing data. cryosphere 10, 149–158, doi: 10.5194/tc-10-149-2016. notz d. & stroeve j. 2016. observed arctic sea-ice loss directly follows anthropogenic co2 emission. science 354, 747–750, doi: 10.1126/science.aag2345. overland j., hanna e., hanssen-bauer i., kim s.-j., walsh j.e., wang m., bhatt u.s. & thoman r.l. 2016. surface air temperature. arctic essays. arctic report card. accessed on the internet at https://arctic.noaa.gov/report-card/report-card-2016/artmid/5022/articleid/271/surface-air-temperature on 23 february 2021. parkinson c.l. 2014. spatially mapped reductions in the length of the arctic sea ice season. geophysical research letter 41, 4316–4322, doi: 10.1002/2014gl060434. r core team 2014. r: a language and environment for statistical computing. vienna: society for statistical computing. reeves r.r. 1998. distribution, abundance and biology of ringed seals (phoca hispida): an overview. nammco scientific publications 1, 9–45, doi: 10.7557/3.2979. reimer j.r., caswell h., derocher a.e. & lewis m.a. 2019. ringed seal demography in a changing climate. ecological applications 29, e01855, doi: 10.1002/eap.1855. ryg m., lydersen c., markussen n.h., smith t.g. & øritsland n.a. 1990. estimating the blubber content of phocid seals. canadian journal of fisheries and aquatic science 47, 1223–1227, doi: 10.1139/f90-142. ryg m., smith t.g. & øritsland n.a. 1990. seasonal changes in body mass and body composition of ringed seals (phoca hispida) on svalbard. canadian journal of zoology 68, 470–475, doi: 10.1139/z90-069. ryg m., smith t.g. & øritsland n.a. 1991. seasonal and developmental changes in reproductive organs of male ringed seals (phoca hispida) in the svalbard area. journal of zoology 224, 93–100, doi: 10.1111/j.1469-7998.1991.tb04790.x. schnute j. 1981. a versatile growth model with statistically stable parameters. canadian journal of fisheries and aquatic science 38, 1128–1140, doi: 10.1139/f81-153. skaret g., prozorkevich d., gjøsæter h. & bogstad b. 2018. influence of ecosystem changes on harvestable resources at high latitudes. proceedings of the 18th russian–norwegian symposium. murmansk, 5–7 june 2018. imr/pinro joint report series 1. bergen and murmansk: institute of marine research and russian federal research institute of fisheries and oceanography. smith t.g. 1973. population dynamics of the ringed seal in the canadian eastern arctic. phd thesis, mcgill university, montreal. smith t.g. 1980. polar bear predation of ringed and bearded seals in the land-fast sea ice habitat. canadian journal of zoology 58, 2201–2209, doi: 10.1139/z80-302. smith t.g. 1987. the ringed seal, phoca hispida, of the canadian western arctic. canadian bulletin of fisheries and aquatic sciences 216. ottawa: department of fisheries and oceans. smith t.g. & hammill m.o. 1981. ecology of the ringed seal, phoca hispida, in its fast ice breeding habitat. canadian journal of zoology 59, 966–981, doi: 10.1139/z81-135. smith t.g., hammill m.o. & taugbol g. 1991. a review of the developmental, behavioral and physiological adaptations of the ringed seal, phoca hispida, to life in the arctic winter. arctic 44, 124–131, doi: 10.14430/arctic1528. smith t.g. & lydersen c. 1991. availability of suitable land-fast ice and predation as factors limiting ringed seal populations, phoca hispida, in svalbard. polar research 10, 585–594, doi: 10.3402/polar.v10i2.6769. smith t.g. & stirling i. 1975. the breeding habitat of the ringed seal (phoca hispida): the birth lair and associated structures. canadian journal of zoology 53, 1297–1305, doi: 10.1139/z75-155. stirling i. 2005. reproductive rates of ringed seals and survival of pups in northwestern hudson bay, canada, 1991–2000. polar biology 28, 381–387, doi: 10.1007/s00300-004-0700-7. stirling i. & lunn n.j. 1997. environmental fluctuations in arctic marine ecosystems as reflected by variability in reproduction of polar bears and ringed seals. in s.j. woodin & m. marquiss (eds.): ecology of arctic environments. pp. 167–182. oxford: blackwell/british ecological society. stirling i. & smith t.g. 2004. implications of warm temperatures and an unusual rain event for the survival of ringed seals on the coast of southeastern baffin island. arctic 57, 59–67, doi: 10.14430/arctic483. teilmann j. & kapel f.o. 1998. exploitation of ringed seals (phoca hispida) in greenland. nammco scientific publications 1, 130–151, doi: 10.7557/3.2984. vanwormer e., mazet j.a.k., hall a., gi v.a., boveng p.l., london j.m., gelatt t., fadely b., lander m., sterling j., burkanov v., ream r., brock p., rea l., smith b., jeffers a., henstock m., rehberg m., burek-huntington k. & goldstein t. 2019. viral emergence in marine mammals in the north pacific may be linked to arctic sea ice reduction. scientific reports 9, article no. 15569, doi: 10.1038/s41598-019-51699-4. von bertalanffy l. 1957. quantitative laws in metabolism and growth. quarterly review of biology 32, 217–231, doi: 10.1086/401873. wathne j.a., haug t. & lydersen c. 2000. prey preferences and niche overlap of ringed seals phoca hispida and harp seals p. groenlandica in the barents sea. marine ecology progress series 194, 233–239, doi: 10.3354/meps194233. wiig ø., derocher a.e. & belikov s.e. 1999. ringed seal (phoca hispida) breeding in the drifting pack ice of the barents sea. marine mammal science 15, 595–598, doi: 10.1111/j.1748-7692.1999.tb00828.x. young b.g. & ferguson s.h. 2013. seasons of the ringed seal: pelagic open-water hyperphagy, benthic feeding over winter and spring fasting during molt. wildlife research 40, 52–60, doi: 10.1071/wr12168. the challenges of a small population exposed to multiple anthropogenic stressors and a changing climate: the st. lawrence estuary beluga review article the challenges of a small population exposed to multiple anthropogenic stressors and a changing climate: the st. lawrence estuary beluga véronique lesage fisheries and oceans canada, maurice lamontagne institute, mont-joli, qc, canada abstract until 2012, the st. lawrence estuary beluga population was considered stable with about 1100 individuals. an abnormally high number of calves reported dead that year triggered a population status reassessment. this review article summarizes the findings from this reassessment and various studies subsequent to it and provides an updated analysis of carcass recovery rates up to 2019. the 2013 review indicated a decreased incidence of cancer in adults, suggesting positive impacts from the regulation of toxic substances (e.g., pcbs and pahs). however, the review also revealed that the population initiated a decline of ca. 1% per year in the early 2000s and had reached a size of ca. 900 individuals by 2012. this decline was accompanied by high inter-annual variability in calf survival and pregnancy rates and by more frequent peripartum complications among dead females. the change in population dynamics coincided with a shift in the st. lawrence ecosystem structure and warmer environmental conditions, suggesting a link through effects on reproductive success and adult female body condition. this was supported by the continued high calf mortality after 2012 and a documented decline of fat reserves in beluga blubber from 1998 to 2016. other factors, such as the exposure to chronic vessel noise, increasing whale-watching activities, high contaminant levels and episodic harmful algal blooms, may also be contributing to the long-term non-recovery and current decline of the population. the strong natal philopatry and complex social system of the beluga likely increase its vulnerability to extinction risk by limiting dispersal. keywords delphinapterus leucas; climate change; population dynamics; noise; food availability; cumulative effects this article is part of the special cluster beluga whales (delphinapterus leucas): knowledge from the wild, human care and tek, which has been funded by mystic aquarium, caff and the norwegian ministry of climate and environment. abbreviations aic: akaike information criterion ci: confidence interval cosewic: committee on the status of endangered wildlife in canada ddt: dichlorodiphenyltrichloroethane dfo: fisheries and oceans canada nafo: north atlantic fisheries organization pah: polycyclic aromatic hydrocarbon pbde: polybrominated diphenyl ether pcb: polychlorinated biphenyl pop: persistent organic pollutant sle: st. lawrence estuary   citation: polar research 2021, 40, 5523, http://dx.doi.org/10.33265/polar.v40.5523 copyright: polar research 2021. © 2021 véronique lesage. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 12 november 2021 competing interests and funding: the author reports no conflict of interest. this work has been supported by the species at risk programme of fisheries and oceans canada. correspondence to: véronique lesage, fisheries and oceans canada, maurice lamontagne institute, box 1000, 850 route de la mer, mont-joli, qc, g5h 3z4, canada. e-mail veronique.lesage@dfo-mpo.gc.ca historical context the beluga (dephinapterus leucas) has a discontinuous circumpolar distribution in the arctic and subarctic regions, with eight populations occurring in canadian waters (stewart & stewart 1989; cosewic 2016). the lack of a dorsal fin and a relatively thick dermis (5–12 mm) make the species particularly well adapted to environments with seasonal and extensive ice cover. the population in the sle, canada, is at the southern limit of the species’ global distribution and probably established itself thereafter the wisconsin glaciation (harington 1977, 2008). the beluga persistence in the sle is probably largely due to the combination of an extensive and seasonal sea-ice cover and the cold and productive environmental conditions that are maintained in this region in part from the influx and upwelling of arctic waters of the labrador current (el-sabh & silverberg 1990). the sle beluga, like several other populations, undertakes seasonal movements, but its extent appears limited to a few tens or hundreds of kilometres (mosnier et al. 2010). the core of its distribution remains in the sle year-round, but an unknown and likely variable proportion of the population moves eastward each fall to winter in the western gulf of st. lawrence (fig. 1). while immigration from other populations might have been notable a century ago (vladykov 1944), the sle beluga population now has the lowest haplotype diversity of all beluga populations and shares none with other populations (postma 2017; skovring et al. 2019). their nuclear genetic diversity is similar to insular populations of mammals (patenaude et al. 1994), suggesting insignificant contributions from neighbouring populations and a distinctly isolated population (postma 2017). fig. 1 relative density of marine traffic in the summer range of sle beluga and their designated critical habitat. traffic includes merchant ships, ferries and some of the whale-watching vessels equipped with automatic identification systems. recreational vessels and two ferries operating downstream of the saguenay river and connecting the north and south shores are not included. white areas indicate areas with no traffic. adapted from chion et al. (2009). the sle beluga population declined from a pristine size estimated at about 8000 individuals in 1866 to a few hundreds of individuals at the end of the 1970s as a result of hunt and bounty programmes that thrived from the 1500s to the mid-1900s (vladykov 1944; reeves & mitchel 1984; hammill et al. 2007). interest in the fate of this population progressively rose with governments and the public, leading to a complete halt of the hunt in 1979 and the population designation as endangered in 1983 by the committee on the status of endangered wildlife in canada (pippard 1985). there were concerns at the time about high contamination of sediments and habitat loss from the development of a marina in tadoussac bay and hydroelectricity-related damming of three rivers considered part of the sle beluga critical habitat (pippard 1985). a carcass monitoring programme was implemented in 1982 (fully in 1983) to monitor the demography and causes of death, pathologies and other illness in this population through tissue sampling. every effort was made to ensure that reporting of carcasses and data collection were consistent over the study period. for instance, the existence of the programme was advertised each spring through a publicity campaign requesting the public to report dead beluga. each reported case was investigated closely to confirm species identity using photographs or visual confirmation by an expert. field data and samples were collected by three or four experts over the 30-year study period, while the necropsies were conducted by five veterinary pathologists from the same institution (for details see lesage, measures et al. 2014; lair et al. 2015). in 1988, another programme was undertaken to monitor trends in distribution and abundance using a systematic and repeatable study design (for details see gosselin et al. 2014). specifically, photographic aerial surveys were flown every 3–5 years along equally spaced transect lines perpendicular to the main axis of the sle using two planes, allowing a high-intensity (ca. 50%) coverage of the entire sle beluga summer range in a single day. these two ongoing programmes confirmed that the population numbered only a few hundred individuals (kingsley & hammill 1991) and that it was amongst the most contaminated marine populations on the planet (martineau et al. 1987; muir et al. 1990; wagemann et al. 1990; martineau et al. 1994), with an incidence of tumours much higher than observed in any other wild population (béland et al. 1993; de guise et al. 1994). from the 1980s through the 2000s, health effects from high contaminant loads were seen as the most imminent threat to the sle beluga population (bailey & zinger 1995). as a result, research efforts were focused on monitoring population size and documenting pathologies, levels of toxic substances and their potential effects on the beluga immune and endocrine systems (reviewed by kingsley 2002; brousseau et al. 2003; lebeuf 2009). toxicological studies revealed that sle beluga had a variety of persistent organohalogen pollutants in their tissues, which were mainly from agricultural and industrial origins. among these pollutants were pcbs, ddt and their metabolites, heavy metals and pahs (e.g., martineau et al. 1987; wagemann et al. 1990; muir et al. 1996; lebeuf 2009). some of these toxic substances were suspected of inducing immunosuppression and of being responsible for the severity, high prevalence and diversity of lesions observed in the population (de guise et al. 1994; martineau et al. 1994; de guise et al. 1995; de guise 1998). pahs, in particular, originating from aluminium smelters, were thought to be responsible for the high rates of cancer documented in the population (martineau et al. 2002). high burdens of some of these persistent organic pollutants were also suspected of having negative effects on the population’s reproductive rate (martineau et al. 1987). however, scientific evidence supporting correlations between pollutants and pathologies or high rates of cancer in sle beluga and whether the sample of recovered carcasses was representative of the living population were debated at the time (addison 1989; theriault et al. 2002; hammill et al. 2003). the long-term programmes monitoring sle beluga carcasses and abundance revealed a stable number of recovered carcasses over time at around 15 individuals per year (median), including up to three calves annually (reviewed by lesage, measures et al. 2014) and a population growing at an abnormally slow pace, if growing at all (hammill et al. 2007). a demographic analysis conducted in 2007 concluded that the adult mortality rate was comparable to arctic beluga populations, the emigration rate was likely minimal and the recruitment rate was low and likely responsible for the apparent lack of recovery of the population (hammill et al. 2007). reasons for the non-recovery and low recruitment rate of the population could be a result of one or multiple anthropogenic stressors acting on sle beluga or their habitat, either independently or in synergy (beauchesne et al. 2020). sle beluga live downstream of highly industrialized and urbanized regions discharging toxic chemical substances which eventually reach their habitat (martel et al. 1986; gearing et al. 1994; gobeil et al. 1995; viglino et al. 2004; lebeuf & nunes 2005). the st. lawrence river represents the main seaway to interior north america (fig. 1). several thousands of ships transit through the sle beluga habitat each year, chronically elevating ambient noise levels (simard et al. 2010; simard et al. 2014; gervaise et al. 2015). adding to this noise and potential disturbance are the multiple ferries and the multi-million dollar whale-watching industry operating year-round or seasonally in the sle beluga critical habitat (gervaise et al. 2012; ménard et al. 2014). the collapse of commercially exploited fish stocks in the 1990s (worm & myers 2003; savenkoff et al. 2007; cairns et al. 2014) and the population increase of potential competitors, such as grey (halichoerus grypus) and harp (pagophilus groenlandicus) seals (hammill et al. 2015; hammill et al. 2017), have modified ecosystem trophodynamics (savenkoff et al. 2007) with potential consequences on prey availability to sle beluga. the canaries in the mine in 2012, an alarmingly high number of newborn calves (n = 16) were reported dead in the sle through the carcass recovery programme. this calf stranding rate was five times higher than the annual maxima of three recorded since the beginning of the programme in 1983 and 16 times higher than the annual median calf stranding rate of one during the period 1983–2019 (lesage, measures et al. 2014). four years earlier (in 2008), eight calves and 14 adults had been found dead, an event attributed at the time to a particularly intense and well-documented harmful algal bloom of the toxic dinoflagellate alexandrium tamarense in the sle, which had also killed hundreds of seabirds, seals and fish (starr et al. 2017). a re-examination of beluga deaths between 1983 and 2012 revealed that an unusually high number of calves (10) had also washed ashore in 2010. this series of high calf mortality events over a short period (2008–2012) led to a coordinated review in 2013, examining long-term information available on multiple aspects of the biology, ecology and the environment of sle beluga. in years subsequent to the review, additional research efforts were undertaken (e.g., diet, noise exposure and impacts, and health effects of contaminants), along with a close monitoring of anomalies across multiple demographic parameters. the following sections summarize the findings from the 2013 review (see also dfo 2014) and the various studies subsequent to it. this review article also updates the analysis of sexand age-specific carcass recovery rates presented as part of the 2013 review (lesage, measures et al. 2014) by incorporating seven additional years of data: 2013–19. population trends and dynamics abundance estimates obtained from visual line-transect surveys (2001–09) and photographic strip-transect surveys (1988–2009) indicated that the 2009 estimate—the latest available for this population at the time of the 2013 review—was the lowest in both survey time series (gosselin et al. 2014). a photogrammetric analysis to detect calves and yearlings (zero and one year in age) in aerial images from the photographic surveys (desrosiers 1994) indicated a decrease in these age class proportions within the population from 15–18% in the 1990s to 3–8% in the 2000s (gosselin et al. 2014). the incorporation of this information in an age-structured population model, along with abundance estimates from the photographic survey time series (1988–2009; summarized by gosselin et al. 2014) and numbers of dead calves and non-calves reported through the carcass monitoring programme (lesage, measures et al. 2014), indicated that several aspects of sle beluga demography had changed over time (mosnier et al. 2015). modelling showed that over the period 1983–2012, the population had shifted from a relatively stable to an unstable state starting around 1999 (fig. 2). from 1983 to 1998, the calf mortality rate was relatively stable (median values: 14–27%), as was the pregnancy rate (about 30%, with small peaks every three years) and the population age structure (50.5% adults, 42% juveniles and 7.5% calves). starting in 1999 and at least until 2012 (last year modelled), an increase in inter-annual variability was noted in calf mortality and pregnancy rates, along with a decline in the proportion of juvenile individuals (1–7 years of age) to 33% in 2012 (mosnier et al. 2015). there was no clear pattern in adult mortality over the modelled period, 1983–2012 (fig. 2). however, the model predicted a change in female reproduction during the last few years of the modelling exercise, when calf mortality was above the long-term median. the reproductive cycle shifted from a three-year cycle, with a third of mature females pregnant each year, to a two-year cycle, with about half of the females pregnant (mosnier et al. 2015). these predicted changes in mortality and reproductive schedules resulted in the population shifting from a stable or slightly increasing trend at about 0.13% per year until 2002 to a declining trend at an average annual rate of –1.13% per year and an estimated population size of 889 individuals (95% ci: 672–1167) in 2012 (mosnier et al. 2015). an additional photographic aerial survey was conducted in 2019 to update population abundance estimates, trends and demographic parameters; results are pending. fig. 2 predicted patterns of (a) calf mortality, (b) adult mortality and (c) pregnancy rate for sle beluga over the period 1983–2012, based on a model incorporating abundance estimates, per cent representation of calves and yearlings from photographs taken on systematic aerial surveys, and carcass recovery for calves (zero year old) and non-calves (one year in age and older). the bold lines emphasize the periods of stability (green: 1983–1998) and instability (red: 1999–2012) in demographic parameters. adapted from mosnier et al. (2015). these model-derived demographic parameters were consistent with independent empirical observations made in the context of a long-term photo-identification programme of live sle beluga from 1989 to 2012 (michaud 2014). specifically, an index for the proportion of immature individuals in the population (grey animals), which included juveniles and young adults, increased slightly from 1989 to the midand late 2000s. consistent with model predictions, this period was followed by a decline in the representation of immature individuals in the population until the last year modelled in 2012 (michaud 2014). field data collections also indicated that years predicted to be associated with high pregnancy rates in the model for the period 2004–2012 were followed by years of high calf production in the field, building our confidence in model predictions. carcass monitoring and cause of death the number of beluga recovered each year through the carcass monitoring programme was variable between years for the different age and sex classes but appeared relatively stable from 1983 to at least 2007 (fig. 3). trends emerged for some age and sex classes when carcasses from the most recent period (2013–19) were added to the time series examined during the review (1983–2012). specifically, the number of dead calves, which had increased in 2008–2012, continued to remain higher than the long-term maxima observed from 1983 to 2007 (three individuals) in 10 of the 12 most recent years, that is, 2008–2019 (fig. 3). in contrast, adult animals (aged eight years or more) tended to be found less often after 2010. a sex-specific analysis revealed that this decrease in adult mortality was entirely attributed to the decline in adult male representation among carcasses (fig. 4a). the exact timing of this decline, however, remains uncertain. the most parsimonious model suggests that it began in the late 1990s (fig. 5; generalized additive model with penalized cubic splines smooth, best model based on lowest aic: 3 knots, edf = 2.0, df = 4, deviance explained = 33.4%). however, the downward trend is heavily driven by the 2010–19 data; allowing more knots to the generalized additive model or using a different statistical approach (e.g., broken stick or sequential analysis) would have resulted in a decline at a later date (not shown). the decrease in male representation among adult carcasses was strongly correlated (pearson’s r = –0.86) with an increase in the sex ratio among deaths towards adult females (fig. 4b; best model: linear regression, df = 3, p < 0.001) even if the absolute number of adult females among carcasses, although variable among years, did not change over the study period (best model: linear regression, df = 3, p = 0.70; fig. 4a). similar to adult females, the number of carcasses of juvenile individuals (i.e., 1–7 years old) remained stable over the study period (fig. 3b; best model: linear regression, df =3, p = 0.09, aic for linear and non-linear regressions were identical). fig. 3 reported cases of dead beluga in the estuary and gulf of st. lawrence over the period 1983–2019. (a) total cases (open circles) and calf carcasses (solid circles) and (b) adult carcasses (eight years or older, solid circles) and juvenile carcasses (1–7 glgs, open circles). the dotted horizontal lines represent the median for each time series. adapted from lesage, measures et al. (2014). fig. 4 number of beluga carcasses recovered in the estuary and gulf of st. lawrence over the period 1983–2019, expressed in terms of (a) number of adult males (back circles) and females (open circles) and (b) percentage of adult females. lines indicate significant regressive relationships over time. adapted from lesage, measures et al. (2014). fig. 5 predicted (curve with 95% ci) and observed (black circles) change in adult male representation among the beluga carcasses recovered in the estuary and gulf of st. lawrence over the period 1983–2019. model selection was based on the lowest aic and degrees of freedom when aic values were within 2 units. non-linear regressions used a penalized cubic regression splines approach for estimating the smoothing parameter. optimal degree of smoothing (number of knots) was determined while taking into account residual deviance and effective degrees of freedom (edf; r package mgcv). note that the timing of the decline is uncertain. the analysis is heavily driven by the 2010–19 data, but is constrained by the number of knots in the analysis. hypotheses to explain this sex-related difference in carcass recovery rate are multiple. while a brief overview is provided here, a thorough investigation of each hypothesis will be required before any conclusion can be drawn from the observed patterns. at least during part of the year, adult males and females are spatially segregated, leading to differential exposure to environmental stressors and differential access to prey items (michaud 1993; mosnier et al. 2016; lesage et al. 2020). the lower representation of adult males in the recovered carcasses could arise from a progressive decrease in detection probability, for instance, as a result of a change in adult male distribution (e.g., due to ecosystem change) towards areas that are less urbanized or less accessible to humans. males could also have decreased in abundance over time compared to females, resulting in fewer relative deaths. male survival may also have increased compared to adult females, for instance, through a progressively lesser exposure to habitat degradation or threat factors, or through access to more profitable prey compared to females. alternatively, the health and survival of both males and females might have improved because of a reduction of potential stressors (e.g., contamination) or higher prey availability but additional sources of mortality prone to affect females might have eliminated these benefits for them. while one of these hypotheses is elaborated below, all of them are plausible. the timing of the change in adult male representation in the recovered carcasses will be a key in assessing the likelihood of each of these hypotheses. complete necropsies of 222 sle beluga conducted between 1983 and 2012 revealed that the main cause of death for this population was an infectious disease, which accounted for half of the cases in juveniles and one-third (32%) of all cases (lair et al. 2016). malignant neoplasia (tumours) was the cause of death for 14% of the beluga and affected only beluga of 28 years or older, whereas dystocia or post-partum complications caused the death of 19% of sexually mature females. a small fraction of deaths were attributed to vessel strikes (4%), primary starvation (2%), fishing-gear entanglement and (1%) and intoxication (one case). the absence of neoplasia was also noted for sle beluga born after 1971 (lair et al. 2016). lair et al. (2016) postulated the existence of a relationship between the reduction of gastrointestinal cancer and the cessation in 1976 of pah emissions from changes in the aluminium production process and stricter environmental regulations. a recent study examining pah–dna adducts in beluga intestine lent support to this hypothesis (poirier et al. 2019). banning pcbs in 1979, which reduced the levels of pcbs in beluga over time (lebeuf, measures et al. 2014), may also have contributed to the progressive disappearance of some neoplastic diseases in this population (martineau et al. 2002; lair et al. 2016). a reduction in non-sex-specific cancers should have improved the health of, and increased survival among, both males and females (i.e., reducing numbers in reported carcasses). whether the improvement in survival occurred equally and simultaneously for males and females, and whether it was progressive or instead occurred when contaminant levels fell below a certain level in beluga tissues, is unknown. parturition-associated mortality, a cause specific to females and which occurred only occasionally from 1983 to the early 2000s, increased in frequency in the 2000s (lair et al. 2016). assuming a persistence of this phenomenon in the 2010s, it could have masked an increase in the survival rate of adult females from an overlapping reduction in cancer-related mortalities and led to the stable pattern in female mortality observed over time (fig. 4a). potential stressors and their effects there are also competing, although not exclusive, hypotheses for the observed high calf mortality and change in the demography of the sle beluga population. these include health problems or impaired reproductive functions from the toxic effects of specific chemical compounds on endocrine and immune functions; perturbation of critical activities (e.g., parturition and foraging) from chronic vessel exposure or isolated or repeated disturbance; fisheryor climate-related changes in ecosystem structure leading to a decrease in habitat quality and prey availability or quality; and recurring stochastic events such as harmful algal blooms (dfo 2014). sle beluga have a long history of exposure to a variety of pops, such as ddt, pcbs, mirex, toxaphene, pah, dioxins and furans (reviewed by lebeuf 2009; see also lebeuf, raach et al. 2014; simond et al. 2017). decreasing in the environment since at least 1987, these pollutants are unlikely to be the primary factor for the recent increase in mortality and population decline (muir et al. 1996; lebeuf, raach et al. 2014); however, new contaminants from the 1980s, such as toxic flame retardants (pbdes), have accumulated at an exponential rate in beluga and their environment in the 1990s, with pbdes remaining at maximum levels in beluga since that time (de wit 2002; lebeuf, measures et al. 2014; lebeuf, raach et al. 2014; simond et al. 2017). pbdes and several other pops can have endocrine-disrupting effects in a variety of species including humans and other mammals, with possible impacts on reproduction, immune system, behaviour and offspring development (reviewed by lebeuf 2009; lebeuf, raach et al. 2014; see also costa et al. 2014; yu et al. 2015). an analysis comparing pbde concentrations in adult females and calves among three periods (1995–2001, 2002–07 and 2008–2011) was unsuccessful at identifying the role of pbdes in the recently elevated frequency of complications at parturition and mortality of calves (lebeuf, measures et al. 2014). this is not to say that pbdes have no detrimental effects on health but that the study, with its specific design, does not reveal a direct relationship between pbde burden and beluga health linked to mortality. a negative effect of pbde homologs on blood thyroid hormone levels has been documented in beluga in svalbard, norway (villanger et al. 2011). the negative effects of hypothyroidism on parturition and foetal health and survival, and of foetal exposure to pbde on calf survival and cognitive abilities, have been reported in humans and other animals (reviewed by lair et al. 2016). while there is yet no evidence for pbde-related hypothyroidism in sle beluga, a correlation between thyroid-related gene expression and levels of some emerging halogenated flame retardants has been documented in this population (simond et al. 2019). however, a mismatch between the period of increased calf mortality and parturition complications (the late 2000s) and of high concentrations of pbdes in sle beluga—which have plateaued since 1998—indicates a need for further investigation (lair et al. 2016). chronic exposure to noise and its potential effects on marine mammals is a concern worldwide (clark et al. 2009; boyd et al. 2011; williams et al. 2015). in the sle, chronic commercial shipping and ferry operations, as well as seasonal whale-watching and recreational activities, raise ambient noise in the beluga habitat (simard et al. 2010; mcquinn et al. 2011; gervaise et al. 2012). between 5000 and 6000 transits from merchant ships are reported each year through the critical habitat of sle beluga (fig. 1; mcquinn et al. 2011). there are 11 marinas near sle beluga critical habitat, four ferry services operating within its bounds, resulting in tens of thousands of ferry transits each year, and a multi-million dollar whale-watching industry, mainly targeting species other than beluga but operating within its critical habitat (ménard et al. 2014). vessel traffic from tourism and whale-watching activities peak in july–august, when sle beluga give birth (sergeant 1986). while sle beluga appear more tolerant to noise than beluga populations in the arctic, where there is comparatively little shipping (finley et al. 1990), sle beluga are not immune to deleterious effects from noise exposure. noise can have negative effects on animals in a number of ways, including masking vocalizations and important signals, reducing acoustic space, diverting attention, disrupting natural behaviour, habituation (i.e., learned deafness) and causing chronic stress (erbe et al. 2018). noise can also limit the energy and time allocated to critical activities like foraging or impair social interactions by, for example, interfering with the acoustic bond between mother and calf (tyack & clark 2000). vocal responses to noise have been documented in sle beluga (lesage et al. 1999; scheifele et al. 2005), and their abandonment of tadoussac bay established after a marina is suspected to be a consequence brought by disturbance from increased vessel traffic and noise exposure (pippard 1985). ferries and other large ships can reduce beluga acoustic space considerably. at the mouth of the saguenay river where as many as three ferries operate simultaneously, acoustic space has been reported at a fraction (30%) of its expected value under natural conditions during half of the time, regardless of the beluga call frequency (gervaise et al. 2012). beluga emit contact calls, which can be heard over ranges that are 18 times larger for adults and subadults than for newborn calves (vergara et al. 2021 [this special cluster]). in a key habitat of the sle (baie sainte-marguerite in the saguenay river), vessel noise reduced the communication range from a median of 6.7–2.9 km for adults and subadults and from a median of 360–170 m for newborn calves. these 57% and 53% reductions in communication range for calls with a known function are evidence that anthropogenic noise from marine traffic may impair communication, and especially mother–calf contact. the exposure of sle beluga to noise varies between habitats and is highest near the shipping lane and at the saguenay river mouth, where a marina and most of the whale-watching companies are based (fig. 1; mcquinn et al. 2011). noise exposure is lowest in habitats located along the south shore, where traffic of all sources is currently light (mcquinn et al. 2011; lesage, mcquinn et al. 2014; roy & simard 2015). on a daily basis, merchant ships in the sle repeatedly expose a substantial proportion of the beluga population (15–53%, depending on traffic direction) to noise levels likely to interfere with their behaviour, and the vast majority of exposed animals (72–81%) are females with calves or juveniles (lesage, mcquinn et al. 2014). shipping traffic in the sle has likely been lighter in the 1990s and 2000s compared to the 1970s or 1980s (dionne 2001). while interannual variations are noted, there is no evidence for any substantial increase in traffic volume at least until 2012 (mcquinn et al. 2011; ménard et al. 2014). whale-watching operations in traditional sectors of activity (i.e., in the sle downstream of the saguenay river where large whales are located; fig. 1) have also remained relatively constant over time, even decreasing slightly in the 2010s (ménard et al. 2014). however, newly established companies specifically targeting beluga have increased whale-watching operations from 2004 to 2012 in non-traditional sectors located in the upstream portion of the sle and within the beluga critical habitat (ménard et al. 2014). recreational activities have also increased in this sector since 2004 (ménard et al. 2014). indicators for the volume of recreational activities in the beluga summer range indicated a coincidence of the high calf mortality events from 2010 and 2012 with a high number of boat-nights in marinas, high per cent days with law-infraction reports for interactions with beluga and clement weather conditions, that is, low precipitation and high air temperature (ménard et al. 2014). physical or acoustic interferences from motorized or non-motorized vessels (e.g., kayaks) with parturition, lactation or mother–calf acoustic bond can induce parturition-related complications or abandonment of the calf. the continuous presence of a human observer during parturition has been reported to induce such complications in cows (mee 2008). although it is unknown if disturbance during the calving season was specifically higher during the high mortality events from 2010 and 2012 than in previous years, the persistence of high calf mortality after 2012 in spite of variable weather conditions suggests that this factor might not be the main cause for the increased calf mortality observed over the past decade. stochastic events such as harmful algal blooms were also among the factors examined in the context of the recent increase in calf mortality. red tides caused by blooms of the dinoflagellate alexandrium tamarense and their associated release of phycotoxins are responsible for outbreaks of paralytic shellfish poisoning and can pose serious health risks for humans and marine organisms (geraci et al. 1989; landsberg 2002). three major red tides were documented over the past two decades in st. lawrence: in 1996, 1998 and 2008 (scarratt et al. 2014; starr et al. 2017). the 2008 red tide was especially well-documented, and a relationship between high cell concentrations of a. tamarense near tadoussac, in the heart of sle beluga habitat, and the high mortality of beluga was established for that year (scarratt et al. 2014). there was no evidence for such red tides during the high mortality events from 2010 and 2012 (scarratt et al. 2014). diet and ecosystem change changes in the st. lawrence community structure have occurred over time as a result of climate variability and anthropogenic factors such as the collapse of demersal fish stocks from overexploitation and ocean warming (worm & myers 2003; savenkoff et al. 2007). these environmental changes likely have modified prey availability, with potential effects on predator population dynamics (e.g., plourde, grégoire et al. 2014). a time-series analysis of 28 ecosystem indices of habitat quality, prey availability and physical environmental variability of the gulf of st. lawrence over the period 1990–2012 highlighted a major shift in the ecosystem in the late 1990s, that is, approximately at the time when beluga population dynamics started to change (plourde, galbraith et al. 2014). the ecosystem shifted from a period of above long-term averages, characterized by a relative abundance of prey and cool environmental conditions, to a period of below long-term averages when gulf of st. lawrence stocks of atlantic spring herring (clupea harengus), atlantic cod (gadus morhua) and other large demersal fish (nafo division 4t) had collapsed and were at their lowest biomass, and when the environment was subject to below-average ice conditions and above-average water temperatures. trend analysis of these variables since 1971 also identified unprecedented extremes in environmental conditions from 2010 to 2012, with particularly high temperatures and low indices for ice duration and volume (plourde, galbraith et al. 2014). these extreme conditions have persisted at least to 2019 (galbraith et al. 2020). an optimum ice condition for calf survival is likely to exist based on the u-shaped relationship predicted between ice duration and calf mortality for sle beluga (williams et al. 2017). in the arctic, females tend to avoid very high or very low ice cover in the fall (barber et al. 2001), supporting model predictions indicating that extreme ice cover may be unfavourable to calf survival. while the physical presence of ice could reduce energy output for adults and calves by offering shelter against storm (barber et al. 2001), its relative benefits to beluga energetics remain uncertain. ice also influences the potential for prey to concentrate in the marginal ice zone (fréchet 1990) and the biomass and timing of spawning of some important beluga prey, such as capelin (mallotus villosus; buren et al. 2014; lesage et al. 2020). as a result, extremes in ice conditions might affect calf survival by reducing energy intake of pregnant females during winter (truchon et al. 2013) and during critical periods such as the spring when intense feeding on prey such as spawning capelin and herring likely occurs before calving (see lesage et al. 2020). elevated sea surface temperatures in the summer months have also been predicted to have a negative effect on calf survival (williams et al. 2017). calf mortality was also inversely related to biomass indices for some beluga prey such as spring herring (nafo division 4t) and demersal species (nafo division 4tw), which, together with sea-ice indices and sea-surface temperature, accounted for 82% of the deviance of the model predicting calf mortality (williams et al. 2017). conversely, prey availability and variations in environmental conditions were not good predictors of adult female mortality and fecundity. such an effect on reproductive success or survival would be likely to arise from extreme changes in adult female body condition. the coincidence of the shift in the st. lawrence community structure and environmental conditions with the change in beluga population dynamics, including higher calf mortalities in periods of extreme conditions (starting around 2010), supports the hypothesis highlighting the role of ecosystem change in beluga population dynamics, potentially through effects on reproductive success and adult female body condition. while data on diet remain fragmentary for this population, studies from the 1930s and from more recent years (1987–2019) suggest that pelagic species such as capelin and herring, sand lance (ammodytes spp.) and large demersal species such as cod (gadus morhua and g. ogac) and redfish (sebastes sp.) may be seasonally important in the sle beluga diet (vladykov 1946; lesage 2014; ferchoui 2019; lesage et al. 2020). evidence for a potential shift in sle beluga diet has been reported through an assessment of sle beluga dietary sources and trophic position from 1988 to 2012, which identified a progressive decrease (approximately one part per mil, equivalent to one trophic level), in a tracer of carbon sources starting around 2003 (lesage 2014). a decline in a tracer of trophic position (nitrogen isotope ratios), although overall modest at approximately 0.6‰ over 10 years, was also observed over the same period (lesage 2014). whether these changes reflect a change in beluga diet or a change in the isotopic signature of their prey is unknown. some prey species and feeding periods may be critical for pregnant or lactating females to ensure successful reproduction and weaning of calves (lockyer 1986; jönsson 1997; miller et al. 2011). this appears to be the case for the sle beluga population during spring feeding, when beluga rapidly accumulate lipid in their blubber (casgrain 1873; vladykov 1944; see lesage et al. 2020). food intake increases 1.5to twofold in late pregnancy and peaks at fourfold their normal intake during the first month after giving birth in captive beluga (kastelein et al. 1994). there is currently little information available on sle beluga body condition. however, a recent study using the sum of blubber fatty acids as an indicator of beluga body condition suggests that it has deteriorated from 1998 to 2016 in both males and females (bernier-graveline et al. 2021). whether a deteriorating body condition in pregnant females played a role in the increased calf mortality and parturition-associated complications observed in recent years is currently unknown (lair et al. 2016). in other mammals, such as cows, nutritional stress during the last semester of pregnancy has been associated with an increased risk of parturition-associated complications (e.g., dystocia) (gruner 1973). disturbance of parturient females and exposure to endocrine-disrupting chemicals such as pbdes also represent risk factors linked to parturition-associated complications (lair et al. 2016). relative importance of the multiple stressors a recent population viability analysis incorporating environmental stressors provided insight into how the sle beluga population was likely to respond to changes in environmental conditions and varying levels of three anthropogenic threats (williams et al. 2017). the analysis incorporated pcb contamination as a proxy for other contaminants, the combined biomasses of demersal fish and spring herring, and noise-mediated effects on foraging efficiency as potential stressors acting on population dynamics, while accounting for potential effects of changing sea-ice conditions and seawater temperatures. with the caveat that this model was data limited and could only account for the relationship between these stressors or the environment and calf mortality, the study indicated that prey availability contributed the most to changes in calf mortality, followed by noise and pcbs. among the management scenarios that explored potential reductions in threats separately and in combination, only the scenario in which all three threats were mitigated simultaneously was likely to create the necessary resilience for the population to persist in the context of the current climate change and warming conditions (williams et al. 2017). conclusions and perspective the very slow population growth rate observed during the 1980s and 1990s despite the total halt on hunting suggests that population growth was already constrained by anthropogenic stressors or sub-optimal environmental conditions associated with local climate, or both. while a harmful algal bloom event was likely responsible for the unusually high calf mortality in 2008, the timing of the change in population dynamics and of increased calf mortality suggests that warming environmental conditions and a decrease in sea-ice extent and duration, with their cascading effects on ecosystem structure (smetacek & nichol 2005), may be key drivers of the current population decrease and the persistently high calf mortality. the apparent deterioration of sle beluga body condition over the past 20 years supports a hypothesis in which climate or fishery-driven impacts on energy balance likely play an important role, by reducing prey availability, quality or both. a similar, although weak, trend in body condition (blubber thickness) and body growth rate has been documented in beaufort sea beluga from 1997 to 2008, although causative factors remain unclear (harwood et al. 2014). poorer body condition can also arise solely from an increase in energy output caused by anthropogenic stressors, for example, repeated avoidance response or disruption of foraging by vessel proximity, or noise-mediated reduction of foraging efficiency (lusseau & bejder 2007; christiansen et al. 2015; pirotta et al. 2015; senigaglia et al. 2016). in food-limited conditions or in the case where females are accompanied by a dependent calf, the ability of an individual to cope with these stressors can be reduced (e.g., williams & loren 2009; senigaglia et al. 2016). therefore, while a food-mediated effect on body condition and reproductive output represents a highly plausible explanation for the poorer body condition and current demographic situation of the sle beluga population, other stressors should not be dismissed as potential contributors to the challenges that this beluga population face in its changing environment. the vulnerability of a population to changes in its environment is a function of its exposure, sensitivity, and adaptive capacity (dawson et al. 2011). exposure depends on the magnitude and rate of change; the sensitivity depends on life-history traits such as habitat specificity, dietary specialization, range size, population size and reproductive rate; and adaptive capacity depends on habitat loss and fragmentation, and also on intrinsic traits such as phenotypic plasticity, and dispersal and colonization capacity (ofori et al. 2017). the beluga is fundamentally a polar species that has adapted over evolutionary time to an environment with a permanent sea-ice cap as its most defining character (o’corry-crowe 2008; kovacs et al. 2011). beluga in the sle are at the southern margin of the species distribution, in an environment where only annually forming ice is present, and its formation is only seasonal. beluga have persisted in this environment over the past 10 000 years (harington 2008) and are presumably well-adapted to an extreme and dynamic environment given their anatomy and primary arctic distribution. climate models are forecasting that the sle will be a nearly ice-free environment within 50–80 years (ruest et al. 2016). the rate of the current climate warming and the high degree of isolation of the sle beluga population may hinder their capacity to adapt to these changes and to survive in an ice-free or nearly ice-free and warm environment (o’corry-crowe 2008). beluga as generalist feeders are better adapted than specialists for coping with changes in prey assemblages (kassen 2002; dennis et al. 2011). in the canadian arctic, where temperate species such as sand lance and capelin are expanding their range as a result of warming conditions (wassmann et al. 2011), beluga responded to this change in prey availability by incorporating these new prey items into their diet (kelley et al. 2010; marcoux et al. 2012), although with unknown consequences related to prey quantity and/or quality on their health. whether a similar pattern will or has occurred in sle beluga as a result of the expansion or higher abundance of more temperate fish or invertebrate species is unknown (lesage et al. 2020). the apparent deterioration of their body condition over the past 20 years (bernier-graveline et al. 2021) suggests that adaptation to the changing ecosystem has been challenging. the reduction in ice cover may increase interspecific competition as other species extend the duration of their stay or expand their range (kingsley 2002). the continuing decrease in oxygen levels (i.e., hypoxia) in waters of the sle and gulf of st. lawrence, partly resulting from the decreased proportion of the oxygen-rich labrador current water entering this region (gilbert et al. 2005), is likely to affect biodiversity and productivity (diaz & rosenberg 2008), with potential effects on the availability of some of beluga prey (lavaud et al. 2019). with 1938 as a baseline, sle beluga occupy an area that represents 65% of their historical range (cosewic 2014). whether this range contraction is the consequence of population decline, as appears to be the case for cook inlet beluga (rugh et al. 2010), or whether it occurred as a result of changes to their habitat or over-hunting at some historical sites is unknown. the species is known for its natal philopatry to summer concentration areas and to migratory circuits within regions, with migration routes and site fidelity being culturally learned (caron & smith 1990; de march & postma 2003; turgeon et al. 2012; colbeck et al. 2013; o’corry-crowe et al. 2018). this cultural inheritance likely also explains the resilience of beluga movements to inter-annual variation in sea-ice conditions, although anomalies in migration patterns can occur in highly anomalous ice years (o’corry-crowe et al. 2016). fidelity to breeding or feeding sites, such as those documented in beluga and other species like southern right whale (eubalaena australis) and humpback whales (megaptera novaengliae), may make these species more prone to extinction risk compared to other cetaceans or to pinnipeds (valenzuela et al. 2009; baker et al. 2013; o’corry-crowe et al. 2018). stable matrilineal groups have long been seen as the cornerstone of beluga society when interpreting the aspects of their ecology and behaviour, but a recent study indicates that beluga groupings can also be organized around close paternal relatives (o’corry-crowe et al. 2020). the complex social system and the high degree of sociality of beluga and other odontocetes may further increase their vulnerability to extinction risk (wade et al. 2012). predictions related to these life-history traits, which appear to reduce the potential for dispersal to new areas more suitable for their survival, could explain in part the absence of recolonization of abandoned or over-hunted sites (mosnier et al. 2010; colbeck et al. 2013). together, these characteristics make the beluga a species that is considered moderately vulnerable to climate change or environmental variability (laidre et al. 2008). however, vulnerability is likely to be higher for the sle beluga population given its location at the southern margin of the species range and the low probability of migrants from other populations replenishing its declining population (o’corry-crowe et al. 2016). the frequency, intensity and geographic extent of harmful algal blooms appear to be increasing worldwide as a result of climate change, coastal eutrophication and other environmental perturbations and are expected to increase the frequency of associated mortality events (van dohal 2000; gulland & hall 2007). these multiple predictions underscore the need for immediate actions to be taken to reduce the population’s exposure to non-climatic stressors. since the first recovery plan was proposed in 1995 for sle beluga (bailey & zinger 1995), multiple actions have been implemented to improve the quality of its acoustic and physical environment (reviewed in dfo 2017). the regulation of toxic chemical substances such as pcbs and pahs, although not in response to beluga decline—they were regulated in the 1970s—may have reduced the incidence of cancer in adult beluga (lair et al. 2016), showing that appropriate specific actions can result in measurable positive impacts on the population. while recovery measures implemented to date have allowed the population to stabilize prior to 2000, they were insufficient to allow the population to grow at the targeted 2% growth rate and to cease decreasing (dfo 2017). additional actions are necessary and have been proposed to address the various threats (dfo 2017, 2020). in the case of noise, a number of actions have been thoroughly examined for their potential benefits and capacity to decrease exposure across beluga habitats (e.g., lesage, mcquinn et al. 2014; chion et al. 2017). the variety of threats, the number of stakeholders that need to be involved in the implementation of recovery actions and inherent delays associated with regulatory processes will remain a challenge, but the timely implementation of additional and necessary recovery measures is possible. acknowledgements i thank dr tracy romano and the organizing committee for their invitation to prepare this paper and presentation at the second international workshop on beluga whale research and conservation in 2019, and the many individuals and organizations whose research contributed to the 2013 review. i am also grateful to serge aucoin and jory cabrol for kindly reviewing and commenting on an earlier version of this manuscript, to drs arnaud mosnier and stéphane plourde for stimulating discussions, to jean-françois ouellet and samuel turgeon (parcs canada) for the map and traffic data, and to drs brian blamer and marie-francoise van bressem for comments on the submission. references addison r.f. 1989. organochlorines and marine mammal reproduction. canadian journal of fisheries and aquatic sciences 46, 360–368, doi: 10.1139/f89-047. bailey r. & zinger n. 1995. st. lawrence beluga recovery plan. toronto: world wildlife fund. baker c.s., steel d., calambokidis j., falcone e., gonćalez-peral u., barlow j., burdin a.m, clapham p.j., ford j.k.b., gabriele c.m., mattila d., rojas-bracho l., straley j.m., taylor b.l., urbàn j., wade p.r., weller d., witteveen b.h. & yamaguchi m. 2013. strong maternal fidelity and natal philopatry shape genetic structure in north pacific humpback whales. marine ecology progress series 494, 291–306, doi: 10.3354/meps10508. barber d.g., saczuk e. & richard p.r. 2001. examination of beluga–habitat relationships through the use of telemetry and a geographic information system. arctic 54, 305–316. beauchesne d., daigle r.m., vissault s., gravel d., bastien a., bélanger s., bernatchez p., blais m., bourdages h., chion c., galbraith p.s., halpern b.s., lavoie c., mckindsey c.w., mucci a., pineault s., starr m., ste-marie a.-s. & archambault p. 2020. characterizing exposure to and sharing knowledge of drivers of environmental change in the st. lawrence system in canada. frontiers in marine science 7, article no. 383, doi: 10.3389/fmars.2020.00383. béland p., de guise s., girard c., lagacé a., martineau d., michaud r., muir d.c.g., norstrom r.j., pelletier é., ray s. & shugart l.r. 1993. toxic compounds and health and reproductive effects in st lawrence beluga whale. journal of great lakes research 19, 766–775. bernier-graveline a., lesage v., cabrol j., lair s., michaud r., rosabal m. & verreault j. 2021. lipid metabolites as predictors of energy reserves in highly contaminant-exposed belugas from the endangered st. lawrence estuary population. environmental research 192, article no. 110272, doi: 10.1016/j.envres.2020.110272. boyd i.l., frisk g., urbàn e., tyack p., ausubel j., seeyave s., cato d., southall b., weise m., andrew r., akamatsu t., dekeling r., erbe c., farmer d., gentry r., gross t., hawkins a., li f.h., metcalf k., miller j.h., moretti d., rodrigo c. & shinke t. 2011. an international quiet ocean experiment. oceanography 24, 174–181, doi: 10.5670/oceanog.2011.37. brousseau p., de guise s., voccia i., ruby s. & fournier m. 2003. immune status of st. lawrence estuary beluga whales. in j.g. vos et al. (eds.): toxicology of marine mammals. pp. 381–403. new york: taylor and francis. buren a.j., murphy h.m., adamack a.t., davoren g.k., koen-alonso m., montevecchi w.a., mowbray f.k., pepin p., regular p.m., robert d., rose g.a., stenson g.b. & varkey d. 2019. the collapse and continued low productivity of a keystone forage fish species. marine ecology progress series 616, 155–170, doi: 10.3354/meps12924. cairns d.k., chaput g., poirier l.a., avery t.s., castonguay m., mathers a., casselman j.m., bradford r.g., pratt t., verreault g., clarke k., veinott g. & bernatchez l. 2014. recovery potential assessment for the american eel (anguilla rostrata) for eastern canada: life history, distribution, reported landings, status indicators, and demographic parameters. dfo canadian science advisory secretariat research document 2013/134. ottawa: fisheries and oceans canada. caron l.m.j. & smith t.g. 1990. philopatry and site tenacity of belugas, delphinapterus leucas, hunted by the inuit at the nastapoka estuary, eastern hudson bay. canadian bulletin of fisheries and aquatic sciences 224, 69–79. casgrain h.r. 1873. la pêche aux marsouins dans le fleuve saint-laurent. (porpoise fishing in the st. lawrence river.) montreal: typographie de l’opinion publique. accessed on the internet at https://ia802906.us.archive.org/12/items/cihm_00526/cihm_00526.pdf on 16 june 2021. chion c., lagrois d., dupras j., turgeon s., mcquinn i.h., michaud r., ménard n. & parrott l. 2017. underwater acoustic impacts of shipping management measures: results from a social–ecological model of boat and whale movements in the st. lawrence river estuary (canada). ecological modelling 354, 72–87, doi: 10.1016/j.ecolmodel.2017.03.014. chion c., turgeon s., michaud r., landry j.-a. & parrott l. 2009. portrait de la navigation dans le parc marin du saguenay–saint-laurent. caractérisation des activités sans prélèvement de ressources entre le 1er mai et le 31 octobre 2007. (overview of the navigation in the saguenay–st. lawrence marine park. characterization of the activities without resource removals between 1 may and 31 october 2007.) unpublished report for parcs canada. accessed on the internet at https://www.pc.gc.ca/-/media/amnc-nmca/qc/saguenay/wet4/publications-scientific/chion-et-al2009_portrait-de-la-navigation-dans-le-parc-marin-du-saguenay-saint-laurent-2007.pdf on 6 july 2021. christiansen f., bertulli c.g., rasmussen m.h. & lusseau d. 2015. estimating cumulative exposure of wildlife to non-lethal disturbance using spatially explicit capture recapture models. journal of wildlife management 79, 311–324, doi: 10.1111/conl.12166. clark c.w., ellison w.t., southall b.l., hatch l., van parijs s.m., frankel a. & ponirakis d. 2009. acoustic masking in marine ecosystem: intuitions, analysis, and implication. marine ecology progress series 395, 201–222, doi: 10.3354/meps08402. colbeck g.j., duchesne p., postma l.p., lesage v., hammill m.o. & turgeon j. 2013. groups of related belugas (delphinapterus leucas) travel together during their seasonal migrations in and around hudson bay. proceedings of the royal society of london b 280, article no. 20122552, doi: 10.1098/rspb.2012.2552. cosewic 2014. cosewic assessment and status report on the beluga whale delphinapterus leucas, st. lawrence estuary population, in canada. ottawa: committee on the status of endangered wildlife in canada. cosewic 2016. designatable units for beluga whales (delphinapterus leucas) in canada. ottawa: committee on the status of endangered wildlife in canada. costa l.g., de laat r., tagliaferri s. & pellacani c. 2014. a mechanistic view of polybrominated diphenyl ether (pbde) developmental neurotoxicity. toxicology letters 230, 282–294, doi: 10.1016/j.toxlet.2013.11.011. dawson t.p., jackson s.t., house j.i., prentice i.c. & mace g.m. 2011. beyond predictions: biodiversity conservation in a changing climate. science 332, 53–58, doi: 10.1126/science.1200303. de guise s. 1998. effects of in vitro exposure of beluga whale leukocytes to selected organochlorines. journal of toxicology and environmental health part a 55, 479–493, doi: 10.1080/009841098158287. de guise s., lagacé a. & béland p. 1994. tumors in st lawrence beluga whales (delphinapterus leucas). veterinary pathology 31, 444–449, doi: 10.1177/030098589403100406. de guise s., martineau d., béland p. & fournier m. 1995. possible mechanisms of action of environmental contaminants on st. lawrence beluga whales (delphinapterus leucas). environmental health perspective 103, suppl. 4, 73–77. de march b.g.e. & postma l.d. 2003. molecular genetic stock discrimination of belugas (delphinapterus leucas) hunted in eastern hudson bay, northern québec, hudson strait, and sanikiluaq (belcher islands), canada, and comparisons to adjacent populations. arctic 56, 111–124, doi: 10.14430/arctic607. dennis r.l.h., dapporto l., fattorini s. & cook l.m. 2011. the generalism–specialism debate: the role of generalists in the life and death of species. biological journal of the linnean society london 104, 725–737, doi: 10.1111/j.1095-8312.2011.01789.x. desrosiers j. 1994. analyse photogrammétrique de la structure et la dynamique de la population de bélugas du saint-laurent. (photogrammetric analysis of the structure and dynamics of the st. lawrence beluga population.) msc thesis, laval university. de wit c.a. 2002. an overview of brominated flame retardants in the environment. chemosphere 46, 583–624, doi: 10.1016/s0045-6535(01)00225-9. dfo 2014. status of beluga (delphinapterus leucas) in the st. lawrence river estuary. dfo canadian science advisory secretariat science advisory report 2013/076. ottawa: fisheries and oceans canada. dfo 2017. st. lawrence estuary beluga. a science-based review of recovery actions for three at-risk whale populations. accessed on the internet at https://waves-vagues.dfo-mpo.gc.ca/library/40680253.pdf on 20 april 2021. dfo 2020. action plan to reduce the impact of noise on the beluga whale (delphinapterus leucas) and other marine mammals at risk in the st. lawrence estuary. ottawa: fisheries and oceans canada. diaz r.j. & rosenberg r. 2008. spreading dead zones and consequences for marine ecosystems. science 321, 926–929, doi: 10.1126/science.1156401. dionne s. 2001. plan de conservation des écosystèmes du parc marin du saguenay-saint-laurent. parcs canada, parc marin du saguenay–saint-laurent. (saguenay–st. lawrence marine park ecosystem conservation plan. parks canada, saguenay-st. lawrence marine park.) quebec: parcs canada. el-sabh m.i. & silverberg n. 1990. oceanography of a large-scale estuarine system: the st. lawrence. new york: springer. erbe c., dunlop r. & dolman s. 2018. effects of noise on marine mammals. in h. slabbekoorn et al. (eds.): effects of anthropogenic noise on animals. pp. 277–309. new york: springer, doi: 10.1007/978-1-4939-8574-6_10. ferchoui b. 2019. nouvelle approche chimique basée sur la bioaccumulation des retardateurs de flamme pour identifier et évaluer la diète du béluga du saint-laurent, delphinapterus leucas. (new chemical approach based on the bioaccumulation of flame retardants to identify and evaluate the diet of the st. lawrence beluga, delphinapterus leucas.) msc thesis, university du quebec à rimouski. finley k.j., miller g.w., davis r.a. & greene c.r. 1990. reactions of belugas, delphinapterus leucas, and narwhals, monodon monoceros, to ice-breaking ships in the canadian high arctic. canadian bulletin of fisheries and aquatic sciences 224, 97–117. fréchet a. 1990. catchability variations of cod in the marginal ice zone. canadian journal of fisheries and aquatic sciences 47, 1678–1683. galbraith p.s., chassé j., caverhill c., nicot p., gilbert d., lefaivre d. & lafleur c. 2020. physical oceanographic conditions in the gulf of st. lawrence in 2018. dfo canadian science advisory secretariat research document 2020/030. ottawa: fisheries and oceans canada. gearing j.n., gearing p.j., noël m. & smith j.n. 1994. polycyclic aromatic hydrocarbons in sediment of the st. lawrence estuary. in r. coillie et al. (eds): proceedings of the twentieth annual aquatic toxicity workshop, october 17–21, 1993, quebec city, quebec. canadian technical report of fisheries and aquatic sciences 1989. pp. 58–64. ottawa: fisheries and oceans canada. geraci j.r., anderson, d.m., timperi, r.j., st. aubin, d.j., early, g.a., prescott, j.h. & mayo c.a. 1989. humpback whales (megaptera novaeangliae) fatally poisoned by dinoflagellate toxin. canadian journal of fisheries and aquatic sciences 46, 1895–1898, doi: 10.1139/f89-238. gervaise c., aulanier f., roy n. & simard y. 2015. mapping probability of shipping sound exposure level. journal of the acoustical society of america 137, el429–435, doi: 10.1121/1.4921673. gervaise c., simard y., roy n., kinda b. & ménard n. 2012. shipping noise in whale habitat: characteristics, sources, budget, and impact on belugas in saguenay–st. lawrence marine park hub. journal of the acoustical society of america 132, 76–89, doi: 10.1121/1.4728190. gilbert d., sundby b., gobeil c., mucci a. & tremblay g.-h. 2005. a seventy-two-year record of diminishing deep-water oxygen in the st. lawrence estuary: the northwest atlantic connection. limnology and oceanography 50, 1654–1666, doi: 10.4319/lo.2005.50.5.1654. gobeil c., johnson w.k., macdonald r.w. & wong c.s. 1995. sources and burden of lead in st. lawrence estuary sediments: isotopic evidence. environmental science and technology 29, 193–201. gosselin j.-f., hammill m.o. & mosnier a. 2014. summer abundance indices of st. lawrence estuary beluga (delphinapterus leucas) from a photographic survey in 2009 and 28 line transect surveys from 2001 and 2009. dfo canadian science advisory secretariat research document 2014/021. ottawa: fisheries and oceans canada. gruner e. 1973. clinical aspects of the nutritional status of the dam and parturition: calving problems and early viability of the calf. current topics in veterinary medicine and animal science 4, 468–477. gulland f.m.d. & hall a.j. 2007. is marine mammal health deteriorating? trends in the global reporting of marine mammal disease. ecohealth 4, 145–150. hammill m.o., den heyer c.e., bowen w.d. & lang s.l.c. 2017. grey seal population trends in canadian waters, 1960–2016 and harvest advice. dfo canadian science advisory secretariat research document 2017/052. ottawa: fisheries and oceans canada. hammill m.o., lesage v. & kingsley m.c.s. 2003. cancers in beluga from the st lawrence estuary. environmental health perspective 111, a77–a78. hammill m.o., measures l.n., gosselin j.-f. & lesage v. 2007. lack of recovery in st. lawrence estuary beluga. dfo canadian science advisory secretariat research document 2007/026. ottawa: fisheries and oceans canada. hammill m.o., stenson g.b., doniol-valcroze t. & mosnier a. 2015. conservation of northwest atlantic harp seals: past success, future uncertainty? biological conservation 192, 181–191, doi: 10.1016/j.biocon.2015.09.016. harington c.r. 1977. marine mammals in the champlain sea and the great lakes. annals of the new york academy of science 288, 508–537, doi: 10.1111/j.1749-6632.1977.tb33640.x. harington c.r. 2008. the evolution of arctic marine mammals. ecological applications 18, s23–s40, doi: 10.1890/06-0624.1. harwood l.a., kingsley m.c.s. & smith t.g. 2014. an emerging pattern of declining growth rates in belugas of the beaufort sea: 1989-2008. arctic 67, 483–492, doi: 10.14430/arctic4423. jönsson k.i. 1997. capital and income breeding as alternative tactics of resource use in reproduction. oikos 78, 57–66, doi: 10.2307/3545800. kassen r. 2002. the experimental evolution of specialists, generalists and the maintenance of diversity. journal of evolutionary biology 15, 173–190, doi: 10.1046/j.1420-9101.2002.00377.x. kastelein r.a., ford j., berghout e., wiepkema p.r. & van boxsel m. 1994. food consumption, growth and reproduction of belugas (delphinapterus leucas) in human care. aquatic mammals 20, 81–97. kelley t.c., loseto l.l., stewart r.e.a., yurkowski m. & ferguson s.h. 2010. importance of eating capelin: unique dietary habits of hudson bay beluga. in s.h. ferguson et al. (eds.): a little less arctic—top predators in the world’s largest northern inland sea, hudson bay. pp. 53–69. dordrecht: springer. kingsley m.c.s. 2002. status of the belugas of the st. lawrence estuary, canada. nammco scientific publications 4, 239–257. kingsley m.c.s & hammill m.o. 1991. photographic census surveys of the st. lawrence beluga population, 1988 and 1990. canadian technical report of fisheries and aquatic sciences 1776. mont-joli: fisheries and oceans canada. kovacs k.m., lydersen c., overland j.e. & moore s.e. 2011. impacts of a changing sea-ice conditions on arctic marine mammals. marine biodiversity 41, 181–194, doi: 10.1007/s12526-010-0061-0. laidre k.l., stirling i., lowry l.f., wiig o., heide-jørgensen m.-p. & ferguson s.h. 2008. quantifying the sensitivity of arctic marine mammals to climate-induced habitat change. ecological applications 18, suppl., s97–s125. lair s., gentes m.-l. & measures l.n. 2015. documentation de l’évolution du protocole d’examen des carcasses de béluga de l’estuaire du saint-laurent de 1983 à 2012. (documentation of the evolution of the protocol for the examination of beluga carcasses in the st. lawrence estuary from 1983 to 2012.) rapport technique canadien des sciences halieutiques et aquatiques 3143. mont-joli: fisheries and oceans canada. lair s., measures l.n. & martineau d. 2016. pathological findings and trends in mortality in the beluga (dephinapterus leucas) population of the st. lawrence estuary, québec, canada, from 1983 to 2012. veterinary pathology 53, 22–36, doi: 10.1177/0300985815604726. landsberg j.h. 2002. the effects of harmful algal blooms on aquatic organisms. reviews in fisheries science 10, 113–390, doi: 10.1080/20026491051695. lavaud r., thomas y., pecquerie l., benoît h.p., guyondet t., flye-sainte-marie j. & chabot d. 2019. modeling the impact of hypoxia on the energy budget of atlantic cod in two populations of the gulf of saint-lawrence, canada. journal of sea research 143, 243–253, doi: 10.1016/j.seares.2018.07.001. lebeuf m. 2009. la contamination du béluga de l’estuaire du saint-laurent par les polluants organiques persistants en revue. (a review of the contamination of the st. lawrence estuary beluga by persistent organic pollutants.) journal of water science 22, 199–233, doi: 10.7202/037482ar. lebeuf m., measures l., noël m., raach m. & trottier s. 2014. a twenty-one year temporal trend of persistent organic pollutants in st. lawrence estuary beluga, canada. science of the total environment 485, 377–386, doi: 10.1016/j.scitotenv.2014.03.097. lebeuf m. & nunes t. 2005. pcbs and ocps in sediment cores from the lower st. lawrence estuary, canada: evidence of fluvial inputs and time lag in delivery to coring sites. environmental science and technology 39, 1470–1478, doi: 10.1021/es049051c. lebeuf m., raach m., measures l., ménard n. & hammill m. 2014. temporal trends of pbdes in adult and newborn beluga (delphinapterus leucas) from the st. lawrence estuary. dfo canadian science advisory secretariat research document 2013/120. ottawa: fisheries and oceans canada. lesage v. 2014. trends in the trophic ecology of st. lawrence beluga (delphinapterus leucas) over the period 1988–2012, based on stable isotope analysis. dfo canadian science advisory secretariat research document 2013/126. ottawa: fisheries and oceans canada. lesage v., barrette c., kingsley m.c.s. & sjare b. 1999. the effect of vessel noise on the vocal behavior of belugas in the st. lawrence river estuary, canada. marine mammal science 15, 65–84, doi: 10.1111/j.1748-7692.1999.tb00782.x. lesage v., lair s., turgeon s. & béland p. 2020. diet of st. lawrence estuary beluga, delphinapterus leucas, in a changing ecosystem. canadian field-naturalist 134, 21–35, doi: 10.22621/cfn.v134i1.2421. lesage v., mcquinn i.h., carrier d., gosselin j.-f. & mosnier a. 2014. exposure of the beluga (delphinapterus leucas) to marine traffic under various scenarios of transit route diversion in the st. lawrence estuary. dfo canadian science advisory secretariat research document 2013/125. ottawa: fisheries and oceans canada. lesage v., measures l., mosnier a., lair s. & béland p. 2014. mortality patterns in st. lawrence estuary beluga (delphinapterus leucas), inferred from the carcass recovery data, 1983–2012. dfo canadian science advisory secretariat research document 2013/118. ottawa: fisheries and oceans canada. lockyer c. 1986. body fat condition in northeast atlantic fin whales and its relationship with reproduction and food resources. canadian journal of fisheries and aquatic sciences 43, 142–147. lusseau d. & bejder l. 2007. the long-term consequences of short-term responses of disturbance experiences from whale watching impact assessment. international journal of comparative psychology 20, 228–236, doi: 10.5070/p4202009991. marcoux m., mcmeans b.c., fisk a.t. & ferguson s.h. 2012. composition and temporal variation in the diet of beluga whales, derived from stable isotopes. marine ecology progress series 471, 283–291, doi: 10.3354/meps10029. martel l.m., gagnon j., massé r., leclerc a. & tremblay l. 1986. polycyclic aromatic hydrocarbons in sediments from the saguenay fjord, canada. bulletin of environmental contamination and toxicology 37, 133–140. martineau d., béland p., desjardins c. & lagacé a. 1987. levels of organochlorine chemicals in tissues of beluga whales (delphinapterus leucas) from the st. lawrence estuary, québec, canada. archives of environmental contamination and toxicology 16, 137–147. martineau d., de guise s., fournier m., shugart l.r., girard c., lagacé a. & béland p. 1994. pathology and toxicology of beluga whales from the st lawrence estuary, quebec, canada: past, present and future. science of the total environment 154, 201–215, doi: 10.1016/0048-9697(94)90088-4. martineau d., lemberger k., dallaire a., labelle p., lipscomb t.p., michel p. & michaelian i. 2002. cancer in wildlife, a case study: beluga from the st lawrence estuary, quebec, canada. environmental health perspective 110, 285–292, doi: 10.1289/ehp.02110285. mcquinn i.h., lesage v., carrier d., larrivée g., samson y., chartrand s., michaud r. & theriault j. 2011. a threatened beluga (delphinapterus leucas) population in the traffic lane: vessel-generated noise characteristics of the saguenay–st. lawrence marine park, canada. journal of the acoustical society of america 130, 3661–3673, doi: 10.1121/1.3658449. mee j.f. 2008. prevalence and risk factors for dystocia in dairy cattle: a review. veterinary journal 176, 93–101, doi: 10.1016/j.tvjl.2007.12.032. ménard n.r., michaud r., chion c. & turgeon s. 2014. documentation of maritime traffic and navigational interactions with st. lawrence estuary beluga (delphinaterus leucas) in calving areas between 2003 and 2012. dfo canadian science advisory secretariat research document 2014/003. ottawa: fisheries and oceans canada. michaud r. 1993. distribution estivale du béluga du st-laurent; synthèse 1986-1992. (summer distribution of the st. lawrence beluga; synthesis 1986-1992.) canadian technical report of fisheries and aquatic sciences 1906. quebec: fisheries and oceans canada. michaud r. 2014. st. lawrence estuary beluga (delphinapterus leucas) population parameters based photo-identification surveys, 1989-2012. dfo canadian science advisory secretariat research document 2013/130. ottawa: fisheries and oceans canada. miller c.a., reeb d., best p.b., knowlton a., brown m.w. & moore m.j. 2011. blubber thickness in right whales eubalaena glacialis and eubalaena australis related to reproduction, life history status and prey abundance. marine ecology progress series 438, 267–283, doi: 10.3354/meps09174. mosnier a., doniol-valcroze t., gosselin j.-f., lesage v., measures l.n. & hammill m.o. 2015. insights into processes of population decline using an integrated population model: the case of the st. lawrence beluga (delphinapterus leucas). ecological modelling 314, 15–31, doi: 10.1016/j.ecolmodel.2015.07.006. mosnier a., larocque r., lebeuf m., gosselin j.-f., dubé s., lapointe v., lesage v., lefaivre d., senneville s. & chion c. 2016. définition et caractérisation de l’habitat du béluga (delphinapterus leucas) de l’estuaire du saint-laurent selon une approche écosystémique. (definition and characterization of the habitat of the beluga (delphinapterus leucas) of the st. lawrence estuary using an ecosystem approach.) secrétariat canadien de consultation scientifique du mpo, document de recherche 2016/052. ottawa: fisheries and oceans canada. mosnier a., lesage v., gosselin j.-f., lemieux lefebvre s., hammill m.o. & doniol-valcroze t. 2010. information relevant to the documentation of habitat use by st. lawrence beluga (delphinapterus leucas), and quantification of habitat quality. dfo canadian science advisory secretariat research document 2009/098. mont-joli: fisheries and oceans canada. muir d.c.g., ford c.a., stewart r.e.a., smith t.g., addison r.f., zinck m.t. & béland p. 1990. organochlorine contaminants in beluga (delphinapterus leucas) from canadian waters. canadian bulletin of fisheries and aquatic sciences 224, 165–190. muir d.c.g., koczanski k., rosenberg b. & béland p. 1996. persistent organochlorines in beluga whales (delphinapterus leucas) from the st lawrence river estuary. ii. temporal trends 1982–1994. environmental pollution 93, 235–245. o’corry-crowe g. 2008. climate change and the molecular ecology of arctic marine mammals. ecological applications 18, suppl., s56–s76. o’corry-crowe g., mahoney a.r., suydam r., quakenbush l., whiting a., lowry l. & harwood l. 2016. genetic profiling links changing sea-ice to shifting beluga whale migration patterns. biology letters 12, 20160404, doi: 10.1098/rsbl.2016.0404. o’corry-crowe g., suydam r., quakenbush l., potgieter b., harwood l., litovka d., ferrer t., citta j., burkanov v., frost k. & mahoney b. 2018. migratory culture, population structure and stock identity in north pacific beluga whales (delphinapterus leucas). plos one 13, e0194201, doi: 10.1371/journal.pone.0194201. o’corry-crowe g., suydam r., quakenbush l., smith t.g., lydersen c., kovacs k.m., orr j., harwood l., litovka d. & ferrer t. 2020. group structure and kinship in beluga whale societies. scientific reports 10, article no. 11462, doi: 10.1038/s41598-020-67314-w. ofori b.y., stow a.j., baumgartner j.b. & beaumont l.j. 2017. influence of adaptive capacity on the outcome of climate change vulnerability assessment. scientific reports 7, article no. 12979, doi: 10.1038/s41598-017-13245-y. patenaude n.j., quinn j.s., béland p., kingsley m. & white b.n. 1994. genetic variation of the st. lawrence beluga whale population assessed by dna fingerprinting. molecular ecology 3, 375–381, 10.1111/j.1365-294x.1994.tb00077.x. pippard l. 1985. status of the st. lawrence river population of beluga, delphinapterus leucas. canadian field-naturalist 99, 438–450. pirotta e., merchant n.d., thompson p.m., barton t.r. & lusseau d. 2015. quantifying the effect of boat disturbance on bottlenose dolphin foraging activity. biological conservation 181, 82–89, doi: 10.1016/j.biocon.2014.11.003. plourde s., galbraith p., lesage v., grégoire f., bourdgages h., gosselin j.-f., mcquinn i. & scarratt m. 2014. ecosystem perspective on changes and anomalies in the gulf of st. lawrence: a context in support of the management of the st. lawrence beluga whale population. dfo canadian science advisory secretariat research document 2013/129. ottawa: fisheries and oceans canada. plourde s., grégoire f., lehoux c., galbraith p.s., castonguay m. & ringuette m. 2014. effect of environmental variability on body condition and recruitment success of atlantic mackerel (scomber scombrus l.) in the gulf of st. lawrence. fisheries oceanography 24, 347–363, doi: 10.1111/fog.12113. poirier m.c., lair s., michaud r., hernandez-ramon e.e., divi k.v., dwyer j.e., ester c.d., si n.n., ali m., loseto l.l., raverty s.a., st. leger j.a., van bonn w.g., colegrove k., burek-huntington k.a., suydam r., stimmelmayr r., pierce wise j. sr., wise s.s., beauchamp g. & martineau d. 2019. intestinal polycyclic aromatic hydrocarbon-dna adducts in a population of beluga whales with high levels of gastrointestinal cancers. environmental molecular mutagenesis 60, 29–41, doi: 10.1002/em.22251. postma l.d. 2017. genetic diversity, population structure and phylogeography among belugas (delphinapterus leucas) in canadian waters: broad to fine-scale approaches to inform conservation and management strategies. phd thesis, university of manitoba. reeves r.r. & mitchell e. 1984. catch history and initial population of white whales (delphinapterus leucas) in the river and gulf of st. lawrence, eastern canada. canadian field-naturalist 111, 63–121. roy n. & simard y. 2015. bruit ambiant et fréquentation de la région de cacouna par le béluga du saint-laurent à l’été 2014 par monitorage acoustique continu. (ambient noise and use of the cacouna region by st. lawrence beluga in summer 2014 by continuous acoustic monitoring.) rapport technique canadien des sciences halieutiques et aquatiques 3141. mont-joli: fisheries and oceans canada. ruest b., neumeier u., dumont d., bismuth e., senneville s. & caveen j. 2016. recent wave climate and expected future changes in the seasonally ice-infested waters of the gulf of st. lawrence, canada. climate dynamics 46, 449–466, doi: 10.1007/s00382-015-2592-3. rugh d.j., shelden k.e.w. & hobbs r.c. 2010. range contraction in a beluga population. endangered species research 12, 69–75, doi: 10.3354/esr00293. savenkoff, c., castonguay, m., chabot, d., hammill, m.o., bourdages, h. & morissette, l. 2007. changes in the northern gulf of st. lawrence ecosystem estimated by inverse modelling: evidence of a fishery-induced regime shift? estuarine, coastal and shelf science 73, 711–724, doi: 10.1016/j.ecss.2007.03.011. scarratt m., michaud s., measures l. & starr m. 2014. phytotoxin analyses in st. lawrence estuary beluga. dfo canadian science advisory secretariat research document 2013/124. ottawa: fisheries and oceans canada. scheifele p.m., andrew s., cooper r.a., darre m., musiek f.e. & max l. 2005. indication of a lombard vocal response in the st. lawrence river beluga. journal of the acoustical society of america 117, 1486–1492, doi: 10.1121/1.1835508. senigaglia v., christiensen f., bejder l., gendron d., lundquist d., noren d.p., schaffar a., smith j.c., williams r., martinez e., stockin k. & lusseau d. 2016. meta-analyses of whale-watching impact studies: comparisons of cetacean responses to disturbance. marine ecology progress series 542, 251–263, doi: 10.3354/meps11497. sergeant d.e. 1986. present status of white whales delphinapterus leucas in the st. lawrence estuary. naturaliste canadien 113, 61–81. simard y., lepage r. & gervaise c. 2010. anthropogenic sound exposure of marine mammals from seaways: estimates for lower st. lawrence seaway, eastern canada. applied acoustics 71, 1093–1098, doi: 10.1016/j.apacoust.2010.05.012. simard y., roy n., giard s. & yayla m. 2014. canadian year-round shipping traffic atlas for 2013: volume 1, east coast marine waters. canadian technical report of fisheries and aquatic sciences 3091 (vol. 1) e. mont-joli: fisheries and oceans canada. simond a.e., houde m., lesage v., michaud r., zbinden d. & verreault j. 2019. associations between organohalogen contaminant and thyroidand steroid-related gene responses in st. lawrence estuary beluga and minke whales. marine pollution bulletin 145, 174–184, doi: 10.1016/j.marpolbul.2019.05.029. simond a.e., houde m., lesage v. & verreault j. 2017. temporal trends of pbdes and emerging flame retardants in belugas from the st. lawrence estuary (canada) and comparisons with minke whales and belugas from the canadian arctic. environmental research 156, 494–504, doi: 10.1016/j.envres.2017.03.058. skovring i., castruita j.a.s., madsen t.m., postma l. & lorenzen e.d. 2019. patterns of mtdna variation in relation to currently recognized stocks of beluga whales, delphinapterus leucas. marine fisheries review 81, 87–97, doi: 10.7755/mfr.81.3–4.4. smetacek v. & nicol s. 2005. polar ocean ecosystems in a changing world. nature 437, 362–368, doi: 10.1038/nature04161. starr m., lair s., michaud s., scarratt m., quilliam m., lefaivre d., robert m., wotherspoon a., michaud r., ménard n., sauvé g., lessard s. & measures l. 2017. multispecies mass mortality of marine fauna linked to a toxic dinoflagellate bloom. plos one 12, e0176299, doi: 10.1371/journal.pone.0176299. stewart b.e. & stewart r.e.a. 1989. delphinapterus leucas. mammal species 336, 1–8, doi: 10.2307/3504210. theriault g., gibbs g. & tremblay c. 2002. cancer in belugas of the st. lawrence estuary. environmental health perspectives 110, a562. truchon m.-h., measures l., l’hérault v., brethes j.-c., galbraith p.s., harvey m., lessard s., starr m. & lecomte n. 2013. marine mammal strandings and environmental changes: a 15-year study in the st. lawrence ecosystem. plos one 8, e59311, doi: 10.1371/journal.pone.0059311. turgeon j., duchesne p., colbeck g.j., postma l.d. & hammill m.o. 2012. spatiotemporal segregation among summer stocks of beluga (delphinapterus leucas) despite nuclear gene flow: implication for the endangered belugas in eastern hudson bay (canada). conservation genetics 13, 419–433, doi: 10.1007/s10592-011-0294-x. tyack p.l. & clark c.w. 2000. communication and acoustic behavior of dolphins and whales. in w.w.w. au & r.r. fay (eds.): hearing by whales and dolphins. pp. 156–224. new york, ny: springer. valenzuela l., sironi m., rowntree v. & seger j. 2009. isotopic and genetic evidence for culturally inherited site fidelity to feeding grounds in southern right whales (eubalaena australis). molecular ecology 18, 782–791, doi: 10.1111/j.1365-294x.2008.04069.x. vergara v., wood j., lesage v., ames a., mikus m.-a. & michaud r. 2021. can you hear me? impacts of underwater noise on communication space of adult, sub-adult and calf contact calls of endangered st. lawrence belugas (delphinapterus leucas). polar research 40, article no. 5521, doi: 10.33265/polar.v40.5521. viglino l., pelletier é. & st-louis r. 2004. highly persistent butyltins in northern marine sediments: a long-term threat for the saguenay fjord (canada). environmental toxicology and chemistry 23, 2673–2681, doi: 10.1897/03-674. villanger g.d., lydersen c., kovacs k.m., lie e., skaare j.u. & jenssen b.m. 2011. disruptive effects of persistent organohalogen contaminants on thyroid function in white whales (delphinapterus leucas) from svalbard. science of the total environment 409, 2511–2524, doi: 10.1016/j.scitotenv.2011.03.014. vladykov v.d. 1944. études sur les mammifères aquatiques. iii. chasse, biologie et valeur économique du marsouin blanc ou béluga (delphinapterus leucas) du fleuve et du golfe du saint-laurent. (studies of aquatic mammals. iii. hunting, biology and economic value of the white whale or beluga [delphinapterus leucas] of the st. lawrence river and gulf.) quebec: département des pêcheries. vladykov v.d. 1946. études sur les mammifères aquatiques. iv. nourriture du marsouin blanc (delphinapterus leucas) du fleuve saint-laurent. (studies of aquatic mammals. iv. food of the white whale [delphinapterus leucas] of the st. lawrence river.) quebec: département des pêcheries. wade p.r., reeves r.r. & mesnick s.l. 2012. social and behavioural factors in cetacean responses to overexploitation: are odontocetes less “resilient” than mysticetes? journal of marine biology 2012(2), article no. 567276, doi: 10.1155/2012/567276. wagemann r., stewart r.e.a., béland p. & desjardins c. 1990. heavy metals and selenium in tissues of beluga whales, delphinapterus leucas, from the canadian arctic and the st. lawrence estuary. canadian bulletin of fisheries and aquatic sciences 224, 191–206. wassmann p., duarte c.m., agustı s. & sejr m.k. 2011. footprints of climate change in the arctic marine ecosystem. global change in biology 17, 1235–1249, doi: 10.1111/j.1365-2486.2010.02311.x. williams r., lacy r.c., ashe e., hall a., lehoux c., lesage v., mcquinn i. & plourde s. 2017. predicting responses of st. lawrence beluga to environmental changes and anthropogenic threats to orient effective management actions. dfo canadian science advisory secretariat research document 2017/027. ottawa: fisheries and oceans canada. williams r. & noren d.p. 2009. swimming speed, respiration rate, and estimated cost of transport in adult killer whales. marine mammal science 25, 327–335, doi: 10.1111/j.1748-7692.2008.00255.x. williams r., wright a.j., ashe e., blight l.k., bruintjes r., canessa r., clark c.w., cullis-suzuki s., dakin d.t., erbe c., hammond p.s., merchant n.d., o’hara p.d., purser j., radford a.n., simpson s.d., thomas l. & wale m.a. 2015. impacts of anthropogenic noise on marine life: publication patterns, new discoveries, and future directions in research and management. ocean & coastal management 115, 17–24, doi: 10.1016/j.ocecoaman.2015.05.021. worm b. & myers r.a. 2003. meta-analysis of cod–shrimp interactions reveals top-down control in oceanic food webs. ecology 84, 162–173, doi: 10.1890/0012-9658(2003)084[0162:maocsi]2.0.co;2. yu l., han z. & liu c. 2015. a review on the effects of pbdes on thyroid and reproduction systems in fish. general and comparative endocrinology 219, 64–73, doi: 10.1016/j.ygcen.2014.12.010. research note crustacean species new to spitsbergen with notes on the polymorphism and the subfossil preservation of cytherissa lacustris (g. 0. sars) t a d e u s z sywula. t a d e u s z namiotko, jerzy sell, andrzej witkowski and marek zajaczkowski sywula. t . , namiotko, t . , sell, j . , witkowski, a. & zajaczkowski, m . 1994: crustacean species new to spitsbergen with notes on the polymorphism and the subfossil preservation of cytherissa lacustris (g. 0. sars). polar research 13(2), 233-235. the copepods limnoralanus macrurus g. 0 . sars and eucyclops serrulatus (fisch.) and the ostracode cytherissa lacustris (g. 0 . sars). hitherto unknown on spitsbergen, were found in lake rewatnet. the last species also in lake svartvatnet. samples from parthenogenetic populations of c. lacustris showed a complete lack of electrophoretically detectable variability at four enzyme-encoding loci, two of which are highly variable in mainland populations. however, morphological variation in the carapace length and nodation was no less than in the mainland populations. the carapace valves of c . lacustris d o not preserve well in the sediments of revvatnet. “ ~ ~ o ~ ~ ~ ~ n s “ ’ t . sywula, marine biology centre, polish academy of sciences, 81-347 gdynia, s w . wojciecha 5 , poland: t . namiotko and j . sell, department of genetics, university of gdansk, 80-822 gdatisk. kladki24. poland; a . witkowski, institute of oceanography, university of gdatisk, 81-378 gdynia, pitsudtkiego 46, poland; m . zajqczkowski, institute of oceanology, polish academy of sciences, 81-967 sopot, powstancdw warszawy 55, poland. an interesting crustacean community was found in samples taken with a dredge on 31 august 1990 from lake revvatnet in spitsbergen (wedel jarlsberg land, 77”02‘n, 15’23’e). this lake is approximately 0.9 km2 in area, with a maximum depth of 27 m, and does not freeze to the bottom. the profundal zone is extensive, its area being ca. 64% of the lake’s surface area; its upper border coincides more or less with the 7 m isobath (kuziemski 1959). the bottom sediment is an organogenic silty mud containing ca. 5.03% organic matter, 0.32% calcium, 3.6% magnesium and 6.0% iron d. w.; 86.6% of particles are of $j < 0.063 mm. as many as 7 species of crustacea were found: a cladoceran macrothrix hirsuticornis norm. et br. (not very abundant); copepods, limno calanus rnacrurus g . 0. sars (very abundant), eucyclops serrulatus (fisch.) f. typica (not very abundant), diacyclops crassicaudis (g. 0. sars) (not very abundant), harpacticus uniremis kroyer (single specimens); and ostracodes can dona rectangulata alm (abundant) and cytherissa lacustris (g. 0 . sars) (abundant). of these species, e. serrulatus and c . lacustris are new to spitsbergen. l . macrurus was previously col lected on spitsbergen in 1977 by i. j ~ r g e n s e n and j. a. eie ( j ~ r g e n s e n & eie 1993). the occurrence of l . macrurus and e. ser rulatus on spitsbergen is not unexpected. both species are widely distributed in the arctic. on the other hand, the presence of c . lacustris was a great surprise. c . lacustris, which has come to be known meta phorically as “the drosophila of paleolimnology” (danielopol et al. 1990), is a strictly specialised lacustrine species with a holarctic distribution which prefers the muddy bottom of a profundal habitat. neither adults nor any larval stages are capable of swimming, nor do they penetrate the littoral zone. the dispersal of c . lacustris between lakes is presumably effected in two stages: a speci men is first swallowed by a fish or macrobenthic invertebrate which itself then becomes the prey of 234 t. sywula et al. a water bird (sywula 1990). however, considering the rapid passage of food through a bird's digestive tract, such long-distance transport over the barents sea hardly seems possible. hence the statement that the occurrence of c. lacustris on spitsbergen was absolutely unexpected. the relatively thick and strongly calcified valves of c. lacustris are usually well preserved in the sediments of mainland lakes: c. lacushis is thus considered a very significant species in pale olimnology. it is noteworthy, however, that in the sediment of rewatnet the valves of this species do not preserve well. this is due to the dissolution of the calcite crystals in the valve's external wall immediately after the animal's death. this decalcification is difficult to explain. although one measurement indicated the water to be slightly acidic (ph 6.8), the composition of the diatom assemblage inhabiting this lake indicates that the water is neutral or slightly alka line: among the 68 taxa found in samples by one of us (a. w.), 34 were alkaliphilous, one was even alkalibiontic (denticula fenuis kutz.), but only 3 were acidophilous. in 1991, an abundant population of c. lacustris was found in another deep spitsbergen lake svartvatnet ( s ~ k a p p land, 76"53'n, 15'40'e); this lake, like rewatnet, does not freeze to the bottom either. except in lake baykal (bronshtein 1947), c. lacustris reproduces parthenogenetically. this is also true of both spitsbergen populations (the presence of males would be conspicuous owing to the pronounced sexual dimorphism in the cara pace structure a characteristic of the family cytherideidae in general). we considered it interesting to compare the degree of morphological polymorphism in the two spitsbergen populations of c. lucustris with that of the central european populations and to assess the genetic relationship between both spitsbergen populations. to do so, we examined patterns of morphological polymorphism in carapace size and nodation as well as genetic variation at enzyme encoding loci. samples were taken on 24 july 1991 (rewat net) and 27 july 1991 (svartvatnet). the cara paces were measured and their nodation was assessed as described by sywula & geiger (1990). homogenates from single living individuals were prepared 1-2 days after sampling and subjected to electrophoresis on cellulose acetate gels in accordance with the methods of hebert & beaton table 1. carapace length and nodation of adult cyrherisso lacl~~hir from two spitsbergen and two austrian lakes (data concerning austrian populations, existing as continuous ones since the atlanticum, from sywula & geiger 1990). specimens number mean coefficient with smooth of length of variation carapace specimens (pm) (%) (%) rewatnet 76 a75 5.2 59 svartvatnet 59 835 2.4 29 blondsee 47 885 3.2 24 attersee 42 915 3.9 41 (1989). 120 adult specimens from each lake were examined. the following enzyme systems were studied from each specimen: glucose-phosphate isomerase (gpi), leucine aminopeptidase (lap) and esterases (est). both gpi and lap in c. lacustris are coded for by a single locus. however, the genetic background of esterases is more com plex; the zymograms from c. lacustris are similar to those from representatives of the genus cyp rinotus, for which the esterases are coded for by two loci (sywula et al. 1991; sywula 1992). all sampled specimens from both populations proved to be genotypically identical and homo zygous at all four loci. by contrast, the mor phological characters were variable (table 1). at least two of the examined loci gpi and est-1 are highly variable in central european populations (sywula 1990; sywula & geiger 1990). studies of other species of parthenogenetic ostracodes also show that genetic variation is com mon (have1 8c hebert 1989; sywula 1992) except in very young populations. these data suggest that even though they consist of several thousand specimens, both spitsbergen populations are still in their initial phase from the population-genetic point of view. they also suggest that the group of successful founders (i.e. those whose genotypes persist in the populations) might be very small and might well be representatives of only one clone. these suggestions seem probable, despite the fact that the present evidence is based on very few loci. populations are enriched with new clones from two sources mutation and migration. the possi bility of successful migration of c. lucustris from the mainland to spitsbergen may be limited in two ways. firstly, the ecological conditions in the crustacean species new to spitsbergen 235 young spitsbergen lakes differ considerably from those in the continental lakes inhabited by c. lacustris; thus, strong selection of immigrants might be expected. secondly, potential immi grants to the existing abundant populations may have, due to some unknown reasons, restricted access to these populations an effect suggested for another parthenogenetic ostracode cyp rinotus incongruens (ramd.) (sywula 1992). thus, it is possible that genetic differentiation in the spitsbergen populations of c . lacustris may be attained mainly by mutation. in the future, there will be a special opportunity for testing the above assumptions while studying temporal changes and the mode of increase in genetic vari ation within and between these large natural populations of this parthenogen. the morphological characters of carapace length and nodation are no less variable in spits bergen populations of c. lacustris than in the old central european ones (table 1; sywula & geiger 1990). in view of the fact that the genetic background in the two spitsbergen populations seems to be at the most only slightly differentiated, it could be inferred that the mor phological differences between them are largely the result of environmental modification of the phenotype. acknowledgements. the authors express their gratitude to s. kwasniewski for his assistance with the sampling. references bronshtein, 2. s. 1947: ostrawda presnych vod. fauna sssr, moskva, leningrad. 339 pp. danielopol, d. l., carbonel, p. & colin, j. p. (eds.) 1990: cytherissa: the drosophila of paleolimnology . bull. insr. gkol. bassin d'aquitaine 47. 310 pp. havel, j. e. & hebert, p. d. n. 1989: apomictic par thenogenesis and genotypic diversity in cyprihpsis uidua (ostracoda: cyprididae). heredity 62, 383-392. hebert, p. d. n. & beaton, m. j. 1989: methodologies for allozyme analysis using cellulose acetate electrophoresis. helena laboratories, beaumont, texas. 32 pp. j@rgensen, i. & eie, j. s. 1993: utbredelsen av zooplankton, bunndyr og fisk i i n n s j e r (the distribution of zooplankton, zoobenthos and fish in lakes and ponds of the mossel penin sula, svalbard). nina forskningsrapport 045, 1-15. trondheim, norway. kuziemski, j. 1959: some results of observations of inland waters on spitsbergen in summer 1958. przeglad geofizyczny 4, 179-197. sywula, t. 1990: the dispersal ability of cytherissa lacurhis. bull. inst. giol. bassin d'aquitaine 47, 135-138. sywula, t. & geiger, w. 1990. genetic and morphological polymorphism in the freshwater ostracod cyrherissa lacurhis (sam) of mondsee and attersee (austria). bull. insr. glol. bassin d'aquitaine 47, 69-81. sywula, t., sell, j., wotniak, g. & sobolewska, a. 1991: non specific esterase polymorphism in marginal populations of cyprinotur (hererocyprir) barbarus (gauthier et brehm) (crustacea, ostrawda). bull. pol. acad. sci. biol. sci. 39, 353-362. sywula, t. 1992: the population genetics of the ostracode cyprinotur incongruens on the basis of esterase loci. biochem. svsr. ecol. 20,735-746. doi:10.3402/polar.v35.26133 r e s e a r c h / r e v i e w a r t i c l e re-assessment of recent (2008�2013) surface mass balance over dome argus, antarctica minghu ding,1,2 cunde xiao,1,2 yuande yang,3 yetang wang,4 chuanjin li,2 naiming yuan,1 guitao shi,5 weijun sun 4 & jing ming 2 1 institute of climate system, chinese academy of meteorological sciences, beijing 100081, china 2 state key laboratory of cryospheric sciences, cold and arid regions environmental and engineering research institute, chinese academy of sciences, lanzhou 730000, china 3 chinese antarctic center of surveying and mapping, wuhan university, 129 luoyu road, wuhan 430079, china 4 college of population, resources and environment, shandong normal university, jinan 250014, china 5 polar research institute of china, shanghai 200136, china keywords snow accumulation; kunlun station; chinare; digital elevation model; deep ice core sites; east antarctic ice sheet. correspondence cunde xiao, institute of climate system, chinese academy of meteorological sciences, beijing 100081, china. e-mail: cdxiao@lzb.ac.cn abstract at dome argus, east antarctica, the surface mass balance (smb) from 2008 to 2013 was evaluated using 49 stakes installed across a 30 �30 km area. spatial analysis showed that at least 12 and 20 stakes are needed to obtain reliable estimates of smb at local scales (a few hundred square metres) and regional scales (tens of square kilometres), respectively. the estimated annual mean smb was 22.995.9 kg m �2 yr �1 , including a net loss by sublimation of �2.229 0.02 kg m �2 yr �1 and a mass gain by deposition of 1.3790.01 kg m �2 yr �1 . therefore, ca. 14.3% of precipitation was modified after deposition, which should be considered when interpreting snow or ice core records produced by future drilling projects. the surface snow density and smb in the western portion of dome argus are higher than in other areas, and these differences are likely related to the katabatic wind, which is strengthened by topography in this sector. a new digital elevation model (dem) of dome argus was generated, confirming that both peaks of the dome can be considered as the summit of the east antarctic ice sheet. findings from this study should be valuable for validating smb estimates obtained from regional climate models and dems established using remote-sensing data. to access the supplementary material for this article, please see the supplementary file under article tools, online. as the highest region of the eais, dome argus is one of the most important candidate sites from which to acquire the oldest east antarctic ice core (fig. 1). previous studies have shown that on-going deep ice core drilling may provide a unique paleoclimate record extending to 1.2 mya (e.g., xiao et al. 2008). in preparation for the project, the surface topography was investigated, and an aws was deployed by the 21st chinare in the austral summer of 2004/05 (zhang et al. 2007; cheng et al. 2009; ma et al. 2010). ice sheet thickness and bed topography were surveyed with ground-based ice-penetrating radar by the 24th chinare in 2007/08 (bo et al. 2009). these efforts contributed important information to the selection of the best site for ice core drilling and for the construction of kunlun station, which is located between the two highest points of dome argus (fig. 1a). smb, snow accumulation rate and surface ice velocity are key parameters for glaciological and meteorological studies. to estimate the smb, snow pit and stake array measurements were collected on the northern peak of the dome argus area. the b activity horizon in the snow pit revealed an smb value of 23 kg m �2 yr �1 during the period 1966�2005 (hou et al. 2007). during the period 2005�08, stake array measurements indicated an smb of polar research 2016. # 2016 m. ding et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 26133, http://dx.doi.org/10.3402/polar.v35.26133 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/26133/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/26133/0 http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/26133 http://dx.doi.org/10.3402/polar.v35.26133 19 kg m �2 yr �1 (ding et al. 2011). during the austral summer of 2004/05, a 109.91 m ice core was drilled to study the preliminary climatic information of dome a; however, the dating results differed greatly between two research groups. one team suggested a 2840-year history for the top 104.42 m, whereas the other group suggested a 41159150-year history for the entire core (jiang et al. 2012; li et al. 2012). additionally, many studies have shown that single site measurements may have low local representativeness (e.g., frezzotti et al. 2007; kameda et al. 2008). better knowledge of the smb distribution over dome argus is needed to support future glaciological studies in this region. in this study, we present a new dem of dome argus, as well as new estimates of smb and surface sublimation rates for the period of january 2008 to january 2013. field observations in january 2008, during the 24th chinare, 49 bamboo poles were installed to measure the smb across a 30 �30 km square area (fig. 1b). the distance between the stakes was ca. 5 km. in january 2011, the 27th chinare re-measured the heights of these stakes and examined the snow layers at sites with damaged stakes. in january 2013, a second re-measurement campaign was conducted. hence, snow height change observations have been collected for two periods: 2008�2011 and 2011�13. the surface density to a depth of 0.20 m was calculated using a tube sampler. to reduce local spatial noise, at least two measurements at each site were collected with an interval of about 4 m. if the difference between the two measurements exceeded 5%, another sample, located so as to form an equilateral triangle with the first two measurement sites, was collected. because of the low snowfall rate and weak winds around dome argus, the densification process is negligible on a time scale of five years (ding et al. 2015). therefore, the use of the surface density to translate snow height changes into smb does not reduce the reliability of the results. the calculated smb uncertainty should be within 2% if visual error of stake height measurement is also considered. gps coordinates of the smb measurement sites were also recorded and used to construct a dem and a surface velocity map for dome argus. the gps data were gathered using rtk and differential gps analysis. in january 2013, two leica as10 gps receivers were used to produce the fig. 1 (a) location of dome argus, east antarctica. the locations of dome fuji, dome b, vostok, dome c and south pole are also shown. (b) sketch map of sites for gps and stake measurements. the base map was generated using qgis 2.6 (http://www.qgis.com/). contour line intervals are 500 m. abbreviations in this article aws: automatic weather station chinare: chinese national antarctic research expedition cv: coefficient of variation da: 100 �100 m stake array on dome argus dem: digital elevation model dz: 30 �30 km stake array around dome argus eais: east antarctic ice sheet ecmwf: european centre for medium-range weather forecasts gps: global positioning system jra-55: japan meteorological agency 55-year re-analysis le: latent heat flux merra: modern-era retrospective analysis for research and applications ncep: national centers for environmental prediction p e: precipitation minus evaporation/sublimation rtk: real-time kinematic analysis shc: surface height change smb: surface mass balance surface mass balance over dome argus, antarctica m. ding et al. 2 (page number not for citation purpose) citation: polar research 2016, 35, 26133, http://dx.doi.org/10.3402/polar.v35.26133 http://www.polarresearch.net/index.php/polar/article/view/26133 http://dx.doi.org/10.3402/polar.v35.26133 dem of dome argus. one gps receiver was used as a reference station at kunlun station and made continuous measurements from 8 to 14 january 2013 at 5 s intervals. the other receiver was used as a roving station to collect data near the stakes. for the roving station, the gps receiver operated in rtk mode and collected data for two minutes under good communication conditions. otherwise, at least 25 min were required to collect data in differential gps mode. the collected data were postprocessed, and the horizontal and vertical errors were estimated to be 1.2 and 3.9 cm, respectively. the dem uncertainty is estimated to be b0.03 m and b0.10 m in the horizontal and vertical respectively. the dome argus stake array, which included a 5 �5 matrix over a 100 �100 m area, was also measured to record snow accumulation during the fieldwork (fig. 1). these observations were used to determine the smb and assess the reliability of local-scale single-stake measurements. here, da designates the smaller scale of the two arrays (100 �100 m), that is the dome argus stake array, whereas dz represents the larger scale array (30 �30 km), comprising 49 stakes installed across a wider area around dome argus. the aws was installed in january 2005 to monitor the meteorology of dome argus, as part of a cooperative effort between china and australia. the type of aws installed at dome argus has been used in many areas of antarctica, and many studies have analysed data collected by these stations (e.g., allison 1998; ma et al. 2010). sensor specifications have been described by ma et al. (2010). results and discussion representativeness of stake measurements smb derived from stake measurements is highly variable in antarctica (e.g., ren et al. 1999; ekaykin et al. 2002; wen et al. 2006). measurements from multiple stakes must be averaged to obtain an estimate of the mean local or regional smb. several studies have reported different averaging intervals to obtain the mean value. for example furukawa et al. (1996), used a 10-stake running average along the syova�dome fuji traverse, higham & craven (1997) calculated smb values using 15-stake averaging, ren et al. (1999) used 21-stake averaging, qin et al. (2000) computed smb values using seven-stake averaging and wen et al. (2006) suggested that a 15stake average is suitable for local-scale studies. considering the different spatial scales explored in these studies, different stake numbers were examined to determine the optimal number that minimizes spatial noise at local and regional scales. to determine this optimal number, the monte carlo method (metropolis & ulam 1949) was used to generate different combinations of stake numbers. then, the cv, also known as relative standard deviation, of each combination was calculated using the following equation: ri;r ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi pr j aj � a � �z r s2 6 6 6 3 7 7 7 i (1) n �25 for da or n �49 for dz; 25r5n �1; j �1, . . ., r; and i �1, . . ., crn. here, s represents the cv, and {aj}, in which j �1,..., r, is a combination when r is the number of degrees of freedom and a ¼ p aj=r. the mean cv is then calculated using this equation: r ¼ pcrn i¼1 ri;r crn (2) to illustrate the relative error on the estimated degree of spatial coherence, we also calculated the cv of si,r for every stake combination; this equation is as follows: dr ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi p ðri;r�rrþ z crn s (3) figure 2 shows variations in s and d as a function of the number of stakes for estimates of the shc, smb and density at the da and dz arrays. multiyear observations clearly increased the reliability of the results. for example, fig. 2a shows that the value of s for the da array decreased from ca. 81% to ca. 19% when the observation period increased from two years (2011�13) to five years (2008�2013). this result agrees with previous ice core studies, many of which noted that at least three years of mean accumulation data are needed to detect localscale spatial variations (e.g., goodwin 1990; magand et al. 2007). the results also show that when the number of stakes increases, s increases and d decreases (fig. 2). however, as shown by the shaded region in fig. 2, s did not exhibit a significant change when the number of stakes increased from 8 to 12 (da) or from 15 to 20 (dz). the slopes of s and d also exhibited very little change for stake numbers exceeding 12 (da, fig. 2c) and 20 (dz, fig. 2d). these results confirm that all errors induced by random measurements have been considered in previous studies. in summary, at the scale of a few hundred square metres, 12 stakes is the minimum number required to obtain reliable estimates of smb, and adding more stakes has m. ding et al. surface mass balance over dome argus, antarctica citation: polar research 2016, 35, 26133, http://dx.doi.org/10.3402/polar.v35.26133 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/26133 http://dx.doi.org/10.3402/polar.v35.26133 relatively little impact on the reliability of results. at a scale of a few tens of square kilometres, 20 stakes is the minimum number. the data used in this paper fulfil these requirements, making the observed snow accumulation rate and calculated smb highly reliable. surface topography of dome argus surfer version 11.0 software was used to generate surface elevation, smb and snow density maps for dome argus (fig. 3). the ‘‘kriging’’ technique was used for interpolation. smoothed elevation contours were plotted at 2 m intervals. the saddle-shaped region of dome argus is very flat, especially in the large white dashed square in fig. 3. the maximum topographic height difference within the 900 km 2 area is b16.50 m, and most of the region has an elevation exceeding 4080 m. in two previous topographic studies of dome argus using dems, different results were attained for the summit of the eais. one study determined that the northern peak is the highest (zhang et al. 2007), whereas the other study suggested that the southern peak is ca. 0.3 m higher (cheng et al. 2009). however, we found that the two peaks have similar elevations. as shown in fig. 3a, the northern peak is ca. 0.08 m higher, although we do not suggest which peak is the actual summit of eais because short-term snow accumulation changes can modify the difference between the peaks, and the vertical uncertainty of the dem is approximately 0.10 m. according to ground-based ice-penetrating radar measurements (bo et al. 2009), there are two mountain peaks below the surface at dome argus, which may explain the fig. 2 the coefficient of variation (s) of smb, shc and density when the stake quantity is increased at (a) the da and (b) dz array; and the coefficient of variation (d) of s of (c) da and (d) dz. the shaded area indicates recommended minimal number of stakes needed to obtain reliable estimates of smb at for (a, c) local and (b, d) regional spatial scales. surface mass balance over dome argus, antarctica m. ding et al. 4 (page number not for citation purpose) citation: polar research 2016, 35, 26133, http://dx.doi.org/10.3402/polar.v35.26133 http://www.polarresearch.net/index.php/polar/article/view/26133 http://dx.doi.org/10.3402/polar.v35.26133 ice sheet surface peaks. kunlun station is located above a subglacial lake between the mountain peaks. this station was chosen for deep ice core drilling because the ice velocity there is very low (3�6 cm yr�1) and the ice is thick (�2800 m). smb of dome argus the smb at each stake in the dz array varied spatially from 14.83 to 40.68 kg m 2 yr �1 , with a cv of 26.0% for the period 2008�2013 (supplementary table s1). conceivably, an annual layer may disappear in locations with extremely low accumulation rates (e.g., kameda et al. 2008). however, no negative values were observed for the dz and da arrays using our multiyear measurements, although one-year measurements show occasional negative values in the da array (ding et al. 2011). spatial variability in smb values is primarily associated with precipitation, surface topography and wind-driven processes (e.g., frezzotti et al. 2007). compared with local effects, such as sastrugi and redistribution by wind drift, precipitation is assumed to be homogeneous at a scale of b100 km. from the meteorological records measured by the aws (fig. 1), the wind speed was usually b3 m s �1 with no prevailing wind direction during the study period, least near the aws (note that winter data were discontinuous, and we therefore determined wind directions in that season using five-year composites). although the topography is very flat in the study region and the smb variations were found to be relatively small, the snow density map shows pronounced spatial differences. the surface density in the western portion of the study area (dz71 in fig. 3b) is much higher than in other regions. we also investigated the surface morphology over dome argus and found that sastrugi with heights of 5�20 cm occur frequently around dz71 (supplementary fig. s1). based on an analysis of the near-surface wind field using ncep data, we found that the prevailing wind here is from the east�south-east to the south, which is corroborated by the direction/shape of the sastrugi. combined with the acceleration induced by topography, the wind speed around dz71 could exceed 3 m s �1 , which would induce a stronger firnification process and lead to hardening of the snow surface. at dz11, dz77 and dz17, the snow is very soft and has a flat surface with active crystallization (supplementary fig. s1), indicating that the air temperature around dome argus can be below the surface snow temperature. under the influence of an inversion layer above dome argus (ma et al. 2010), the vapour pressure close to the surface can reach or even exceed saturation, resulting in frost build-up at the snow surface. the estimated mean smb value over dome argus was 22.995.9 kg m 2 yr �1 during the period 2008�2013. compared with the surface snow density, the smb in the western area was only slightly greater than in other parts across the study region (see fig. 3a). altogether, no large regional variations in the net smb were observed. our new estimated mean smb is comparable to the estimated mean net snow accumulation rates for the northern peak of dome argus based on the b radioactivity peak for the period 1965�2005 (hou et al. 2007) and at kunlun station for the period 1966�2009 (wang et al. 2013). however, our result is 3.9 kg m 2 yr �1 higher than the previous results for the da stake array (ding et al. 2011). generally, aws records are considered very accurate because the ultrasonic sounder is sensitive to shcs. however, the results presented by ma et al. (2010) are overestimated: the 24th chinare found that a snow fig. 3 (a) map of the mean (2008�2013) smb across dome argus interpolated from stake observations. black contours are surface elevations (wgs84 ellipsoid) with intervals of 2 m based on gps data from 27th chinare. the small and large white dashed squares cover the 64 km2 and 400 km2 areas surveyed by zhang et al. (2007) and cheng et al. (2009), respectively. the solid white square represents kunlun station, the red star represents da stake array and the red triangles represent the two summits of dome argus. (b) map of surface density interpolated from observations. m. ding et al. surface mass balance over dome argus, antarctica citation: polar research 2016, 35, 26133, http://dx.doi.org/10.3402/polar.v35.26133 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/26133/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/26133/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/26133/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/26133/0 http://www.polarresearch.net/index.php/polar/article/view/26133 http://dx.doi.org/10.3402/polar.v35.26133 dune had formed just below the sensor in january 2008 (supplementary fig. s2). in antarctica, the smb is determined by precipitation, surface sublimation erosion/deposition due to divergence/convergence of snow drift transport, wind-driven sublimation and meltwater runoff. indeed, most of the inconsistency of p e in re-analysis data sets such as the ecmwf’s era-40, the ncep re-analysis data and observed smb can be attributed to wind-driven processes in the coastal and katabatic wind regions (scambos et al. 2012; das et al. 2013). however, because of the weak wind (b3 m s �1 ) over dome argus, wind-driven processes represent a small contribution to the smb, as was previously inferred by a regional atmospheric climate model (racmo2.3) that included drifting snow processes (van wessem et al. 2014). we compared our smb with p e estimates in climate re-analysis data sets, including the ecmwf’s era-40 and era-interim re-analysis, jra-55 and merra (table 1). the era-40, era-interim and merra data sets underestimate the observed smb by ca. 50%, whereas the jra55 p e closely resembles the observed values. the dry bias in most re-analysis products may largely result from the fact that contributions of clear-sky precipitation to the smb are not included in these re-analyses. the consistency between the jra-55 data set and the field observations may be attributed to a better representation of observed precipitation in the jra-55 data set (ebita et al. 2011). sublimation of dome argus the le over dome argus was calculated using the following analytical expression from the bulk-aerodynamic method (oke 1987): le ¼ qlsce uðq � qsþ; (4) where r�(r0p)/p0 is the air density at the dome argus aws, r0 and p0 are the air density (1.29 kg m �3 ) and pressure (1013 hpa) at standard sea level, respectively, and p is the measured surface air pressure at the aws (hpa). ls is the latent heat of sublimation for snow (2.834 mj kg -1 ). ce is the bulk transfer coefficient for humidity, which has been suggested to be 0.00129 when the atmosphere is stable and 0.002 when the atmosphere is unstable (ma 2009). u and q are the mean wind speed and specific humidity at the height of 4 m, respectively; and qs is the surface specific humidity, which is calculated using the glacial surface saturation vapour pressure (es) (bolton 1980). the parameters qs and es are calculated as follows: qs � ees=p:ðe ¼ 0:622þ (5) es ¼ 6:112 exp 17:67ts ts þ 243:5 " # (6) at half-hourly steps, sublimation ms (mm w.e.) is calculated from the le, that is, ms �le/ls. because the aws wind measurements were not consistent during wintertime, all records during the period 2005�2010 were averaged to obtain mean meteorological parameters from 1 january to 31 december. finally, a data set was constructed having 97% of the daily wind speed records. despite the surface air being constantly saturated at dome argus (ma et al. 2010), the conditions are unfavourable for snow sublimation. the extremely low temperature limits the specific humidity of the air. moreover, the snow surface is usually colder (63.5% of the time) than the air, reducing the vertical humidity gradient. nonetheless, because all of the surface energy balance fluxes are very small over the antarctic plateau (van den broeke et al. 2006), the le remains important for heat loss on a daily basis. this hypothesis can be validated using the bulk-aerodynamic method. at dome argus, even during summertime, the le remains below 3 w m �2 due to the low temperatures and weak winds. based on the monin�obukhov similarity theory, we simulated the five-year averages of daily mean table 1 compilation of smb (kg m2 yr�1) estimates for dome argus. period method smb references 1966�2005 b radioactivity peak 23 hou et al. 2007 1965�2009 b radioactivity peak 21 wang et al. 2013 1980�2002 era-40 10 wang et al. 2013 2005�07 automatic weather station 31.7 ma et al. 2010 2005�09 stake array 19 ding et al. 2011 1979�2012 era-interim 8 this paper 1979�2012 jra-55 21 this paper 1979�2012 merra 13 this paper 2008�2013 stake 22.995.9 this paper fig. 4 five-year (2005�2010) averages of estimated daily mean sublimation (blue) and deposition (negative sublimation, red) at dome argus. surface mass balance over dome argus, antarctica m. ding et al. 6 (page number not for citation purpose) citation: polar research 2016, 35, 26133, http://dx.doi.org/10.3402/polar.v35.26133 http://www.polarresearch.net/index.php/polar/rt/suppfiles/26133/0 http://www.polarresearch.net/index.php/polar/article/view/26133 http://dx.doi.org/10.3402/polar.v35.26133 sublimation at dome argus. the results are shown in fig. 4. the total sublimation was determined to be �2.2290.02 mm w.e. yr�1, which primarily occurred between november and january. deposition occurred primarily between february and october, accounting for �1.3790.01 mm w.e. yr�1, which is much less than the values of other plateau stations, such as dome fuji (�5.5 mm w.e. yr �1 ; kameda et al. 1997). this difference can be partially attributed to the fact that dome argus is farther from the coast and has a higher elevation than dome fuji, which leads to less moisture transport from the ocean. during the polar night, sublimation and deposition can be negligible because of the low air temperature (approximately �59.78c during april and september) and low specific humidity (approximately 0.013 g kg �1 during april and september). in summary, the net loss by sublimation at the surface reaches �0.8590.02 mm w.e. yr �1 (kg m �2 yr �1 ). this result indicates that the total mass input at dome argus is 25.195.9 kg m �2 yr �1 and that the net surface mass exchange (by sublimation/ deposition) is equal to, on average, 14.3% of the total mass input (or 15.7% of the estimated mean net smb), which is very important for snow compositional changes through post-depositional processes, and for the interpretation of ice core climatic archives. conclusions using data from a 49-stake network over a 30 �30 km area from 2008 to 2013 and high precision gps measurements, we calculated the annual mean smb of dome argus, antarctica, to be 22.995.9 kg m 2 yr �1 , which agrees well with the previous estimation based on b radioactivity (hou et al. 2007; wang et al. 2013) and jra-55 re-analysis data, but not with era-40, aws, era-interim and merra. this indicates that studies evaluating antarctic smb should be carried out with caution. our simulation showed that sublimation and deposition processes have huge influence on the smb of the dome area. this has been confirmed at dome c (3 mm w.e. yr �1 ; frezzotti et al. 2004), dome fuji (1.6 mm w.e. yr �1 , kameda et al. 1997) and vostok (2�4.4 mm w.e. yr�1, ekaykin et al. 2004), although the net mass loss presented here may be the lowest ( �0.8590.02 mm w.e. yr�1) on the eais because of the extremely low air temperature and the highest elevation. compared with the other deep ice core sites, dome argus has the lowest smb and ice velocity. the new surface map generated by our study, along with the bed topography and thermal conditions studied previously, suggests that dome argus could be an optimal location for drilling the oldest ice core. however, some sites between dome fuji and dome a, have even lower smb values, for example site nus07-6, with a value of 16.090.4 kg m 2 yr �1 (anschütz et al. 2011), which could make them other good candidates for deep ice core drilling if their surface ice velocities and ice thicknesses meet the necessary criteria. acknowledgements this study is funded by national key basic research program of china (2013cba01804), the national science foundation of china (41425003; 41576182; 41206179) and the state oceanic administration (chinare2016). references allison i. 1998. surface climate of the interior of the lambert glacier basin, antarctica, from automatic weather station data. annals of glaciology 27, 515�520. anschütz h., sinisalo a., isaksson e., mcconnell j.r., hamran s.-e., bisiaux m.m., pasteris d., neumann t.a. & winther j.-g. 2011. variation of accumulation rates over the last eight centuries on the east antarctic plateau derived from volcanic signals in ice cores. journal of geophysical research* atmospheres 116, d20103, doi: http://dx.doi.org/10.1029/ 2011jd015753 bo s., siegert m.j., mudd s.m., sugden d., fujita s., cui x.b., jiang y.y., tang x.y. & li y.s. 2009. the gamburtsev mountains and the origin and early evolution of the antarctic ice sheet. nature 459, 690�693. bolton d. 1980. the computation of equivalent potential temperature. monthly weather review 108, 1046�1953. cheng x., gong p., zhang y., sun z. & wei f. 2009. surface topography of dome a, antarctica, from differential gps measurements. journal of glaciology 55, 185�187. das i., bell r.e., scambos t.a., wolovick m., creyts t.t., studinger m., frearson n., nicolas j.p., lenaerts j.t.m. & van den broeke m.r. 2013. influence of persistent wind scour on the surface mass balance of antarctica. nature geoscience 6, 367�371. ding m., xiao c.d., li c.j., qin d.h., jin b., shi g.t., xie a.h. & cui x.b. 2015. surface mass balance and its climate significance from the coast to dome a, east antarctica. science in china*earth sciences 58, 1787�1797. ding m.h., xiao c.d., li y.s., ren j.w., hou s.g., jin b. & sun b. 2011. spatial variability of surface mass balance along a traverse route from zhongshan station to dome a, antarctica. journal of glaciology 57, 658�666. ebita a., kobayashi s., ota y., moriya m., kumabe r., onogi k., harada y., yasui s., miyaoka k., takahashi k., kamahori h., kobayashi c., endo h., soma m., oikawa y. & ishimizu t. 2011. the japanese 55-year reanalysis ‘‘jra-55’’: an interim report. sola 7, 149�152. m. ding et al. surface mass balance over dome argus, antarctica citation: polar research 2016, 35, 26133, http://dx.doi.org/10.3402/polar.v35.26133 7 (page number not for citation purpose) http://dx.doi.org/10.1029/2011jd015753 http://dx.doi.org/10.1029/2011jd015753 http://www.polarresearch.net/index.php/polar/article/view/26133 http://dx.doi.org/10.3402/polar.v35.26133 ekaykin a., lipenkov v., barkov n., petit j. & massondelmotte v. 2002. spatial and temporal variability in isotope composition of recent snow in the vicinity of vostok station, antarctica: implications for ice core record interpretation. annals of glaciology 35, 181�186. ekaykin a., lipenkov v.y., kuzmina i.n., petit j.r., massondelmotte v. & johnsen s.j. 2004. the changes in isotope composition and accumulation of snow at vostok station, east antarctica, over the past 200 years. annals of glaciology 39, 569�575. frezzotti m., pourchet m., flora o., gandolfi s., gay m., urbini s., vincent c., becagli s., gragnani r., proposito m., severi m., traversi r., udisti r. & fily m. 2004. new estimations of precipitation and surface sublimation in east antarctica from snow accumulation measurements. climate dynamics 23, 803�813. frezzotti m., urbini s., proposito m., scarchilli c. & gandolfi s. 2007. spatial and temporal variability of surface mass balance near talos dome, east antarctica. journal of geophysical research*earth surface 112, f02032, doi: http:// dx.doi.org/10.1029/2006jf000638 furukawa t., kamiyama k. & maeno h. 1996. snow surface features along the traverse route from the coast to dome fuji station, queen maud land, antarctica. proceedings of the nipr symposium on polar meteorology and glaciology 10, 13�24. goodwin i. 1990. snow accumulation and surface topography in the katabatic zone of eastern wilkes land, antarctica. antarctic science 2, 235�242. higham m. & craven m. 1997. surface mass balance and snow surface properties from the lambert glacier basin traverses 1990� 94. antarctic crc research report 9. hobart: antarctic climate and ecosystems cooperative research centre. hou s., li y., xiao c. & ren j. 2007. recent accumulation rate at dome a, antarctica. chinese science bulletin 52, 428�431. jiang s., cole-dai j., li y.s., ferris d.g., ma h.m., an c.l., shi g.t. & sun b. 2012. a detailed 2840 year record of explosive volcanism in a shallow ice core from dome a, east antarctica. journal of glaciology 58, 65�75. kameda t., azuma n., furukawa t., ageta y. & takahashi s. 1997. surface mass balance, sublimation and snow temperatures at dome fuji station, antarctica, in 1995. proceedings of the nipr symposium on polar meteorology and glaciology 11, 24�34. kameda t., motoyama h., fujita s. & takahashi s. 2008. temporal and spatial variability of surface mass balance at dome fuji, east antarctica, by the stake method from 1995 to 2006. journal of glaciology 54, 107�116. li c., xiao c.d., hou s.g., ren j.w., ding m.h. & guo r. 2012. dating a 109.9 m ice core from dome a (east antarctica) with volcanic records and a firn densification model. science in china*earth sciences 55, 1280�1288. ma y. 2009. characteristic parameters of near surface layer of the traverse route from zhongshan station to dome-a, east antarctica. phd thesis, chinese academy of meteorological sciences, beijing. ma y., bian l., xiao c., allison i. & zhou x. 2010. near surface climate of the traverse route from zhongshan station to dome a, east antarctica. antarctic science 22, 443�459. magand o., genthon c., fily m., krinner g., picard c., frezzotti m. & ekaykin a. 2007. an up-to-data qualitycontrolled surface mass balance data set for the 90-180 e antarctica sector and 1950�2005 period. journal of geophysical research*atmospheres 112, d12106, doi: http://dx.doi. org/10.1029/2006jd007691 metropolis n. & ulam s. 1949. the monte carlo method. journal of the american statistical association 44, 335�341. oke t.r. 1987. boundary layer climates. 2nd edn. new york: routledge. qin d., ren j.w., kang j.c., xiao c.d., li z.q., li y.s., sun b., sun w.z. & wang x.x. 2000. primary results of glaciological studies along an 1100 km transect from zhongshan station to dome a, east antarctic ice sheet. annals of glaciology 31, 198�204. ren j., qin d. & allison i. 1999. variations of snow accumulation and temperature over past decades in the lambert glacier basin, antarctica. annals of glaciology 29, 29�32. scambos t., frezzotti m., haran t., bohlander j., lenaerts j.t.m., van den broeke m.r., jezek k., long d., urbini s., farness k., neumann t., albert m. & winther j.-g. 2012. extent of low-accumulation ‘wind glaze’ areas on the east antarctic plateau: implications for continental ice mass balance. journals of glaciology 58, 633�647. van den broeke m., reijmer c., van as d. & boot w. 2006. daily cycle of the surface energy balance in antarctica and the influence of clouds. international journal of climatology 26, 1587�1605. van wessem j., reijmer c.h., morlighem m., mouginot j., rignot e., medley b., joughin i., wouters b., depoorter m.a., bamber j.l., lenaerts j.t.m., van den berg w.j., van den broeke m.r. & van meijgaard e. 2014. improved representation of east antarctic surface mass balance in a regional atmospheric climate model. journal of glaciology 60, 761�770. wang y., sodemann h., hour s.g., masson-delmotte v., jouzel j. & pang h.x. 2013. snow accumulation and its moisture origin over dome argus, antarctica. climate dynamics 40, 731�742. wen j., jezek k.c., monaghan a.j., sun b., ren j. & huybrechts p. 2006. accumulation variability and mass budgets of the lambert glacier�amery ice shelf system, east antarctica, at high elevations. annals of glaciology 43, 351�360. xiao c., li y., allison i., shugui h., dreyfus g., barnola j.-m., jiawen r., lingen b., shenkai z. & kameda t. 2008. surface characteristics at dome a, antarctica: first measurements and a guide to future ice coring sites. annals of glaciology 48, 82�87. zhang s., dongchen e., wang z., zhou c. & shen q. 2007. surface topography around the summit of dome a, antarctica, from real-time kinematic gps. journal of glaciology 53, 159�160. surface mass balance over dome argus, antarctica m. ding et al. 8 (page number not for citation purpose) citation: polar research 2016, 35, 26133, http://dx.doi.org/10.3402/polar.v35.26133 http://dx.doi.org/10.1029/2006jf000638 http://dx.doi.org/10.1029/2006jf000638 http://dx.doi.org/10.1029/2006jd007691 http://dx.doi.org/10.1029/2006jd007691 http://www.polarresearch.net/index.php/polar/article/view/26133 http://dx.doi.org/10.3402/polar.v35.26133 bookreviews25(1).indd 75polar research 25(1), 75–79 book reviews review of innocents in the arctic. the 1951 spitsbergen expedition, by colin bull (2005). fairbanks, ak: university of alaska press. 254 pp. isbn 10: 1-8899963-73-9. thor b. arlov dept. of sociology and political science, norwegian university of science and technology, no7491 trondheim, norway, thor.bjorn.arlov@svt. ntnu.no. as the title implies, this book is the story of an expedition to spitsbergen in 1951. it would be an exaggeration to state that the expedition was actually sent forth by the university of birmingham, but the ten young members were all attached to that institution as graduate or undergraduate students or, in two cases, as lecturers. one of the latter had by 1951 reached the considerable age of 28, but otherwise the field party consisted of men in their early twenties. in other circumstances this information might be of little relevance, but in this particular case age—or rather lack of experience—does play a certain role, alluded to by the book’s title. no doubt the university lent moral and to some extent practical support to the expedition, but it is obvious from reading the book that the initiative and most of the effort came from the participants themselves. thus, an important lesson is learned already at the outset of the story: enthusiasm can bring you a long way, even to the arctic. the expedition was scientific in its intent and lay-out. in one sense it was a follow-up of a previous birmingham expedition in 1948, in which lionel weiss took part. he was also the initiator of the 1951 venture. having discovered carboniferous fossils among significantly older metamorphic rocks of the so-called hecla hoek basement complex (pre-cambrian to silurian age), weiss was eager to find out more about the tectonic forces that had formed the land. therefore, he planned to make stratigraphical investigations in the area around st. jonsfjorden on the west coast of spitsbergen, the largest island in the svalbard archipelago. the main research object was to interpret and map the structural geology south of st. jonsfjorden, but studies of quaternary phenomena, like beach terraces and glaciers, were also to be undertaken. geophysical investigations were on the programme too, but largely had to be abandoned due to lack of time and proper instruments. hence, the author himself, who was the on-board physicist, was more or less demoted to rock-carrier. not that it seems to have bothered him too much. although science plays an important part in the book, innocents in the arctic is neither a scientific report nor a popular textbook on the geology of western spitsbergen. it is rather a chronologically ordered documentary augmented by more personal reminiscences of the expedition, which perhaps places the book in the broad category of travel literature. this concept could seem traditional and uninspiring for a broader public without particular interest in arctic science and it requires a good writer to work out well. luckily, colin bull is a good writer and editor, but it is relevant to question whether the audience for this kind of book might be rather narrow. more of this later. as mentioned above, the book maintains a traditional chronological form. following a list of participants, a foreword by former director of the 76 book reviews norwegian polar institute, olav orheim, and a preface by the author, there are 11 chapters dealing with the expedition itself from start to finish. the first five describe the preparations in england and the hazardous voyage of the expedition vessel miss mabel, first from her berth in cork to liverpool, then via scottish canals and across the north sea to norway. when they eventually reached tromsø, already seriously delayed, the local authorities refused to let miss mabel continue to svalbard, as she was obviously unfit for navigation in arctic waters. concequently, the group had to board the passenger ship lyngen, which brought them safely to longyearbyen. chapters 6 through 10—roughly half the book— deal with the field expedition to st. jonsfjorden. i regard this as the main part, where the organization of camps and fieldwork under very harsh weather conditions is vividly described. almost in passing we are also taught a bit of geology, often in a humorous way and on a scientific level i think most readers can handle. since the expedition split into two main parties, an inland and a beach party (no pun intended), the chronology is not strictly maintained in these chapters, but this is elegantly solved by the author, who manages to stitch the events of the five weeks together and tie up loose ends. chapter 11 is about the return voyage of miss mabel, which proved every bit as eventful as the trip to norway. the concluding chapter 12, called “aftermath”, is mostly about the later lives and careers of the expedition members and answers an obvious question from the reader: what became of these guys afterwards? there is also a list of publications from this and related expeditions and a very adequate index. the book is well illustrated with photographs, some of which are quite good, and there are a few maps and drawings as well. the publication has a pleasing lay-out and a decent print quality. the proof-reading must have been thorough; there are remarkably few typos and errors as far as i can see. for those of us who have had the good fortune of spending a few seasons in svalbard, whether on business or for pleasure (or both), innocents in the arctic has a lot to offer. for one thing we learn about the conditions in svalbard more than 50 years ago, which is interesting from a historical perspective. anyone with a love for the wilderness can easily understand and sympathize with the joys of experiencing magnificent arctic landscape and wildlife, the pleasures and frustrations of camping and the special personal relationships that grow from spending time together during fieldwork under challenging conditions. it is also fascinating to learn how the expedition members tackled challenges in a time before helicopters, ski-doos, gps, gore-tex and all those wondrous things that have made life more than bearable for the polar scientist. one cannot but be impressed by the amount of research they were able to do “back then”, fuelled by tea and biscuits and limitless enthusiasm. it is the way that colin bull relates all this that gives the book its foremost quality, in my opinion. thanks to careful note-taking and valuable contributions from the other expedition members, and probably frequent meetings of the group, he has been able to compile a comprehensive story that renders details even down to bits of conversation. this adds life and character to an account that might otherwise have been an old-timer’s tedious recollection of events half a century ago. the narrative is easyflowing, low-key and sprinkled with understated humour and subtle irony—a style many of us appreciate as “typically british”. no bragging or macho language here to spoil the relaxed tone of the book, thank you very much. i suspect ageing has done this narrative and its author well. this is a quite personal book, which is both a strength and a possible weakness. on the positive side the personal details, including the photographs, bring us closer to the characters, to the extent that we may feel we actually are getting to know them properly. this adds credibility and a human touch to the book and elevates it from a mere account to a real story, and a charming one, too. on the more critical side, i sometimes get the feeling that the book is primarily intended for friends and relatives of the expedition members, if not indeed for themselves. it is good fun, at least for a while, to read about camp routines and the drying of sleeping bags, but i would have liked to have learned even more about the geology and the scientific work they did, because those sections of the book are exceptionally well written. i do recommend this book to all readers of polar research, without any reservations. whether it will also appeal to readers outside the (admittedly large) “arctic family” is another question—only time and circulation will tell. i think the book has qualities to engage many categories of readers, but it certainly helps to have already an interest in polar areas and outdoor science. polar bears killed in svalbard 1987-1992 ian gjertz. sissel aarvik and reidar hindrum gjcrlz. 1.. aarvik, s. & hindrum. r. 1993: polar bears killed in svalbard 1987-1992. polar research 12(2). 107109. a total of 26 polar bears have been killed in svalhard since january 1987. fifteen of these cases wcrc self defense. four precautionary measures, six acts of mcrcy and one unknown. twclvc of the 15 self defense c ~ s c s occurrcd in the wilderness: nonc occurrcd in populatcd areas. most self defence cases involved non rcsidents of svalhard and hence people not familiar with polar bear bchaviour and encounters. 1. gjertz. nor.rk polarinstituti. p . 0. box 505. 91 70 longyeorbyen, norway: s. aaroik and r. hindrum. sysselmannen pd soatbard, 9170 longyearbyen. norway. introduction take refuge near populated areas and are thus the implementation of the agreement on the conservation of polar bears resulted in a total ban on all polar bear hunting in norwegian ter ritory since 1973 (anonymous 1974). after july 1973 polar bears have only been shot in acts of self defense, as precautionary measures or in acts of mercy. all such cases are considered as police matters and are either investigated or authorized by the governor of svalbard. gjertz & person (1987) reviewed the recorded information on incidences where polar bears had been killed or had injured people in svalbard from 1973 to 1987. a total of 50 such cases had been registered. the purpose of the present study was to review all known incidents of polar bears killed i n sval bard in the period 1987-1992, including incidents where bears were killed due to conflicts with humans and also those where bears were killed in acts of mercy. methods in this study the term “serious confrontation” refers to cases where bears have been shot in self defense or as a precautionary measure, and to cases where people have been injured or killed by bears. in addition, bears are sometimes put to death as acts of mercy, for example they have been deemed unable to survive due to old age, injury or disease. this requires special permission from the governor and occurs primarily when bears considered a possible threat. the data on bears killed have been obtained from the governor’s files and the local newspaper, sualbardposten. the governor’s files consist either of police records or of the con servation officers’ records. the latter also contain some biological information on the bears killed. when possible, conservation officers collect data on the sex, age class, zoological length, girth, blubber thickness and weight of the animal. in many cases bears are killed in such remote areas that reports of these incidents reach the governor too late for the systematic gathering of any bio logical information. results a total of 26 polar bears have been reported killed in svalbard since january 1987 (table 1). twelve bears were killed in the summer months of july and august. these same months were the period with most killings in self defense (8). june and november were the only months without any bears being killed. the geographical distribution of the 26 killing cases (15 self-defense) is as follows: northern coasts of svalbard, including nordaustlandet, 9 (8); the eastern coasts of svalbard, including edg ecbya and hopen, 8 (6); the western coast of svalbard 3; and the inner fjord regions of spits bergen, 6 (1). most cases occurring in the fjord areas of spitsbergen were precautionary measures or acts of mercy. 108 i. gjertz et al. table 1 . polar bears killed in svalbard 1987-1992. date site cause 870126 870413 870727 870730 870806 8708 15 870823 870825 870909 880101 880222 880223 880427 8809 12 881012 881227 89081 1 900806 yo0726 900826 920323 920509 9205 10 920524 890802 y 10730 80'24" 26"e van kculcnfjorden' austfonna austfonna agardhbukta rijpfjorden hopen hopen kapp lee, e d g e ~ y a mosselbukta rijpfjorden isbjornhamna 80"30'n 8"e krosspynten 83"n, ne of k v i t ~ y a sveagruva sveagruva sveagruva rijpfjorden beckerfjellct agardhbukta blafjorddalen minkinfjellet lsbjernharnna kapp dufferin ishjernhamna ?? sd sd sd s d sd pm am sdipm' sd sd am sd sd pm pm pm am sd sd sd/am sd am am sd am involved b t s s t s c c l t p t l s l p p t t s p p t p sip sip sex age-class length male male female male male female male male male cub young young subadult 182 adult 196 adult 240 adult 225 cub 140 adult adult adult 250 male adult male subadult 180 male subadult 197 male adult 230 male adult 210 male subadult 188 male adult 210 male subadult male adult male adult 248 female adult 195 male adult 255 girth (cm) 135 1 i7 175 125 i 0 0 138 1 i4 120 145 135 1 i7 164 1 i4 i42 blubber >2 >2 0 c-2 0 0 c-2 &2 (l2 >2 >2 >2 c-2 >2 0 >2 0 ca 2(!4 i30 ca 150 310 ca 150 150 340 i = included in gjcrtz & persen 1987 sd = self dcfcnce; pm = precautionary measure; am = act of mercy: ?? = unknown; b = boat; t = tourist: s = scientist; c = station crew; l = local person: p = police; length = zoological length in cm. blubber = thickness in cm measured along lower back. 0 indicates no blubber present. = human casualty no biological data existed on the age of 3 bears killed nor on the sex of 5 bears. of the 23 bears of known age-class, 14 were adults. of the 21 bears of known sex, 18 were males. except for one two-year-old bear in the company of its mother and a sibling (table 1, 870413), all the bears were believed to have been alone when shot. discussion the polar bears killed in svalbard between 1987 and 1992 can be classified according t o two main categories, those killed in serious confrontations and those killed for other reasons. since polar bears are totally protected in svalbard, incidences falling in the latter category must be authorized by the governor. such authorization has hitherto been granted only to policemen and conservation officers. these cases are almost exclusively acts of mercy. it is governmental policy to let old, sick or injured bears die natural deaths unless they take residence close to populated areas. in such cases, to avoid potential serious confrontations and to accommodate public concern for the ani mals' welfare, these bears may be killed. according to larsen (1986) population esti mates for polar bears in the svalbard area nearly doubled from 1967-1970 to 1980-1983, and sur vival rates increased from the period 19541970 to the period 1977-1982. it is therefore probable that the number of bears reaching senility has increased today. no previous review exists of polar bears killed in acts of mercy in svalbard. we do not know if these cases occur more fre quently now than in previous years, but we think this is probable. gjertz & persen (1987) found that tourists and scientists were involved in 7 out of a total 9 serious polar bears killed in svalbard 1987-1992 109 confrontations that occurred in the months june through august. this was believed to be due to two factors: inexperience with bears and the remoteness of the areas visited. these people often visit the northern and eastern coasts of the archipelago where bears are most common. this trend was found also in the present study. tourists and scientists were involved i n 13 of 15 cases of serious confrontations, all of which occurred in the northern or eastern parts of the archipelago. we believe that many of these incidents could have been avoided had those involved been more experienced with high arctic conditions. in the period 1987-1992 only one serious con frontation resulted in human casualty. human casualties are rare, and apart from the case in 1987, we know of only four cases after 1970 in svalbard. three of these were reviewed by gjertz & persen (1987). the fourth case occurred in b j ~ r n ~ y a in november 1971 (anonymous 1972). basing their estimates on crude information, gjertz & persen (1987) suggested that many bears involved in serious confrontations in svalbard were young. this same tendency was noted by stenhouse et al. (1988). in the present study we see the same trend among bears killed i n serious confrontations, and these are most often males. this is in agreement with fleck & herrero (1988) who state that subadult males are at least twice as likely to become involved in an aggressive interaction than any other age and sex class. her rero & fleck (1990) found that four of thirteen male bears that attacked humans were t h i n or skinny, suggesting nutritional stress. the infor mation of blubber thickness contained in table 1 is inadequate to determine whether bears killed in self defense are bears that are naturally stres sed. as can be expected, blubber measurements (table 1) show that bears killed in acts of mercy tend to be nutritionally stressed. based on the results of this study it seems possible to conclude that those most prone to kill bears in self-defense are inexperienced non residents of svalbard who are visiting the remote northern and eastern areas of svalbard. the prob lem bears are predominantly males, often imma ture. references anonymous 1972: telcgrafist p;l b j ~ r n o y a slitt i hjel av i s b j ~ r n . polurhoken 1971-1 972. p. 154. anonymous 1974: om samtykke ti1 ratifikasjon av avtalc av 15 november 1973 om vcrn av i s h j ~ r n i arktis. srorrings proposisjon 6 (1974-1975). 15 pp. fleck, s. & hcrrero, s. h . 1988: polar bear-human conflicts. prepared for: parks canada. prairie region and department of renewable resources. 155 pp. gjertz. i . & persen. e. 1987: confrontations between humans and polar bears in svalbard. polar reseurch 5 . 253-256. herrero. s . & fleck, s. 1990: injury to people inflicted by black, grizzly o r polar hears: recent trends and new insights. inrernurionul conference on beur reseurch und munugetnetit 8 . 25-32. larscn, t. 1986: population biology of the polar bear (ursus maritimus) in the svalbard area. norsk polurinst. skr. 184. stcnhouse, g . b . . lee, l . j . & poolc k . g. 1988: some characteristics of polar bears killed during conflicts with humans in the northwest territories, 1976x6. arctic 41. 2 7 5 2 7 8 . 55 pp. perceptions of decision-makers about a potential forum of cooperation in the eastern part of the north american arctic research article perceptions of decision-makers about a potential forum of cooperation in the eastern part of the north american arctic mathieu landriault,1 jean-françois savard1 & anna soer2 1école nationale d’administration publique, gatineau, qc, canada 2school of political studies, university of ottawa, ottawa, on, canada abstract cooperation in the arctic region has been fruitful in the past few decades, generating several multilateral organizations and forums covering the entire circumpolar north. in many cases, forums were created to serve as catalysts, bringing together decision-makers from different backgrounds in a conference setting to promote dialogue and the exchange of ideas. to enquire about the possibility of creating a forum of cooperation in the eastern north american arctic, a total of five governmental officials from canada, denmark, nunavut, québec and greenland, and one elected representative from greenland were interviewed with the same set of five questions. the governmental officials were in senior positions at the main department focusing on foreign affairs in their respective jurisdictions. most thought that a new forum of cooperation in the region would be highly desirable, on the grounds of shared interests, common identity and cultural affinities. consensual positions were also found regarding the central role that civil society would play in a new cooperative venue and on sub-national governments assuming a leading role to spearhead the initiative. following these interviews, it is difficult to pinpoint one government that could alone spearhead this new forum of cooperation. however, the governments of nunavut and greenland were the most enthusiastic about such a new regional forum. given greenland’s drive to complete independence, this type of forum could prove to be a statement of diplomatic motivation and ambition, tilting toward proto-diplomacy and an international policy that prepares the terrain for complete autonomy. keywords cross-border cooperation; diplomacy; autonomy; people-to-people ties, economic development; governance abbreviations bear: barents euro-arctic region naa: north american arctic   citation: polar research 2023, 42, 9026, http://dx.doi.org/10.33265/polar.v42.9026 copyright: © 2023 m. landriault et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 16 march 2023 competing interests and funding: the authors report no conflict of interest. this research was funded by the secrétariat du québec aux relations canadiennes of the government of québec. correspondence: mathieu landriault, école nationale d’administration publique, 283 alexandre taché, wing d, door 13, gatineau, qc j9a 1l8, canada. e-mail: mathieu.landriault@enap.ca   introduction cooperation in the arctic region has been fruitful in the past few decades, with the creation of several multilateral organisations and forums covering the entire circumpolar north. however, cooperation is also possible at the sub-regional level. this article focuses on such a possibility by assessing interest in establishing a cooperation forum in one specific arctic-sub-region, the eastern part of the naa. numerous initiatives have emerged to stimulate cooperation among various actors—national governments, sub-national governments, indigenous groups, companies, non-governmental organizations, etc.—in the region. in many cases, forums were created to serve as catalysts, bringing together decision-makers from different backgrounds in a conference setting to promote dialogue and the exchange of ideas. the annual arctic circle assembly (iceland) and the arctic frontiers conference (norway) are good examples. in other cases, multi-stakeholder efforts have been undertaken to bring local governments in northern regions (northern forum, initially based in alaska and at the moment in russia) or companies (arctic economic council) around the same table to discuss topics of common interest. these governance initiatives have been mostly successful in bringing together decision-makers and sharing their perspectives on the challenges and opportunities they face in the arctic. however, this type of cooperation has seldom produced tangible results or initiatives in the form of action programmes and implementable measures (landriault et al. 2019). multilateral arctic institutions have been studied extensively. among these, the arctic council is the most studied and analysed multilateral forum in the scholarly literature. specific initiatives, such as the polar code adopted at the international maritime organization, have also been extensively studied. in comparison, cross-border cooperation initiatives in the arctic have been overlooked. these cooperative mechanisms have been more circumscribed, focusing on joint management of a shared region. bear is the best illustration of such a venture. surfacing from the immediate post-cold war era, the impetus emerged from a perceived necessity by norway, sweden, finland and russia to cooperate in the barents region. although the russian invasion of ukraine brought the initiative to a halt, the region cooperated for 30 years on issues of common interests. the nordic council, the west nordic council and the beaufort sea partnership are examples of other targeted, region-specific cooperative ties and organizations. these different initiatives provide a rather nuanced picture of arctic cooperation, one emphasizing different sub-regional political landscapes. we will look at governments in the eastern part of the naa and the prospect of establishing a forum of cooperation among them that would work on multiple issues. naturally, the bear cooperation represents a relevant precedent. a potential eastern naa forum would also include sub-national governments: the cases of the northern forum and the west nordic council constitute examples of regional cooperation involving sub-national governments. we need to understand what factors contributed to the success or failure of these regional organizations to understand the potential for, and limitations of, an eastern naa forum. this article will focus on the following key main line of inquiry: is a forum of cooperation possible in the eastern naa? on the basis of interviews with governmental decision-makers in the region, we will investigate the potential of, and obstacles to, formalized cooperative ties in this region. our hypothesis is that there is willingness to cooperate in the eastern naa, especially emanating from nunavut and greenland, but practical limitations and limited resources discourage this collaborative scenario. arctic cross-border cooperation and the naa each cross-border initiative in the arctic region was carried out for specific reasons. for example, the bear was established in 1993 through the adoption of the kirkenes declaration. the initiative was mostly driven by norwegian, swedish and finnish desires to engage with post-soviet russia. finland, for one, had established economic ties with russia in the 1980s and 1990s. norway spearheaded the bear initiative and invested significant diplomatic and financial resources to “handle both the opportunities and the problems arising out of the post-cold war reality of east–west relationships” (zimmerbauer 2013: 93), especially with north-west russia. bear projects have been designed to tackle ‘low-politics’ issues, such as environmental protection, transportation, and social-economic development, so as to avoid controversies. bear institutions were conceptualized to facilitate state-to-state contacts while empowering sub-national administrations and units to establish a dialogue and pursue shared objectives, especially in a context in which russian sub-national units were more independent from their central government (akimov 2021). the multiplicity of activities and programmes managed by the bear (before the russian invasion of ukraine) is an example of successful cooperation. however, the bulk of the investments and initiatives was initiated by finland, sweden or norway, with russia as the main recipient. cooperation was not entirely reciprocal as the main objective for norway was to maintain a pathway of engagement with russia and to limit the possible impact of cross-border phenomenon, such as pollution (landriault et al. 2019). cooperation involving sub-national governments has been fraught with obstacles linked to political willingness and limited resources. for example, the northern forum was created in the early 1990s—spearheaded by the us state of alaska—as an occasion for sub-national governments to reap the peace dividend of the immediate post-cold war. the organization’s influence waned when key members, including alaska, lost interest in the forum, citing fiscal constraints. membership in the northern forum also declined because of the limited common interests among members (tsui 2016). the current state of the northern forum serves as a cautionary tale that illustrates how effective institutional cooperation between sub-national governments must be defined around a specific geographical area and that members must perceive that there are significant benefits to reap from the initiative: sub-national governments typically do not possess ample financial resources to develop their international relations, so international initiatives must generate results (landriault et al. 2021). areas of cooperation within the northern forum are also eclectic, with little coherence among them, leading members to question the relevance of the organization. other multilateral cooperation initiatives have been fostered by similar factors. the creation of the arctic caucus in the pacific northwest economic region can be significantly attributed to already strong social and economic relations between alaska and the canadian territory of yukon. multilateral mechanisms such as the nordic council and the west nordic council were founded on cultural affinities, perceptions of a common neighbourhood and economic ties (anderson 1963; larsen 1984; nielsson 2013). lately, the importance of the west nordic council, including greenland, iceland and the faroe islands, grew as a result of arctic developments and increased international attention toward the region. west nordic council members further relied on the organization to “share experience, expertise and information on issues of regional concern” (bailes & ólafsson 2017: 57) although the resources available to the council to pursue these objectives are quite limited (caddell 2022). overall, key actors leading multilateral initiatives are pivotal for the creation of cooperative mechanisms. these leading governments are the ones perceiving significant geopolitical changes deserving the creation of formal regional institutions, whether the end of the cold war (bear, northern forum) or arctic regional developments (west nordic council). financial resources to facilitate collaboration have also been a defining factor differentiating successful and failed regional institutions. disparate membership, vague mandates and unclear agendas have also impacted multilateral initiatives. formal government-to-government multilateral cooperative mechanisms are scarce in the eastern part of the naa, which encompasses greenland, nunavut, nunavik (northern quebec) and newfoundland-and-labrador. governments in the naa have been convened to take part in dialogues and summits, but no sustained organization, forum or initiative has emerged from these encounters. for example, while the naa administrations that higginbotham and spence brought together in 2018 and 2019 shared similar priorities, interests and outlooks on cooperation, there were issues, including limited financial means, that prevented formalized cooperation (higginbotham & spence 2018). this outcome could also be explained by the fact that the naa is a heterogeneous space covering a vast geographic area. on the other hand, more fruitful and dynamic cooperation at the sub-regional level between alaska and yukon can be observed, both jurisdictions co-managing a common border and environment and enjoying significant trade relations with one another. rather than the entire naa, the eastern part of the naa presents as a more natural setting for multilateral cooperation. however, some key factors must be considered before assessing the possibility of a cooperation forum in the eastern naa. for one, greenland’s quest for independence can prove an impediment as much as an incentive for further cooperation. disagreements over competencies between denmark and greenland have occasionally led to frictions as danish competencies over security and defence can overlap with greenlandic jurisdictions over natural resources (ackrén & jakobsen 2015; henriksen & rahbek-clemmensen 2017). on the other hand, the government of greenland’s para-diplomatic activities have been increasing, the region signing agreements with sovereign states and opening diplomatic offices abroad. much of these activities have consisted of either engaging with great powers (us, china) or cooperating with other nordic countries, including iceland, while cooperation at the governmental level with northern canada and naa neighbours has been limited. additionally, air connections exist between greenland and iceland but not between greenland and northern territories in canada although most of the greenlandic population resides in western rather than eastern greenland. as for canada’s northern jurisdictions, federal structures in canada generate different types of government with their own set of competencies. for the eastern naa, one is a territory (nunavut) and the other two are part of provinces (nunavik in quebec, labrador in newfoundland-and-labrador). for nunavut, the status of territory limits its power, and a devolution agreement that would transfer competencies and permanent funding from the federal government to nunavut has yet to be signed. issues of underfunding, especially for international initiatives, persist. the same could be said to a lesser extent about nunavik and labrador, with provincial priorities (for quebec) and a financial predicament (for newfoundland-and-labrador) that do not bode well for significant diplomatic initiatives. on the other hand, civil society has built bridges and spearheaded cooperative endeavours. the inuit tapiriit kanatami represents inuit living in canada, while the inuit circumpolar council brings together inuit communities living in canada and greenland. moreover, civil societies in canada and greenland have been active in working toward protecting the pikialasorsuaq north water through the pikialasorsuaq commission. it remains to be seen whether civil society partnerships can spill over into government-to-government cooperation. this article will present findings derived from interviews of naa governmental decision-makers and elected representatives to uncover whether there is an appetite for a multilateral forum of cooperation in the eastern naa. through these interviews, we asked participants about the issues that could be addressed through such a forum and what they believed to be the most salient obstacles to such an initiative. methods governmental officials from canada, denmark, nunavut, québec and greenland were interviewed. (we reached out several times to governmental officials and elected representatives from newfoundland-and-labrador, but we were unable to organize interviews.) in total, seven public servants and one elected representative were interviewed. these officials were in senior positions at the main department focusing on foreign affairs in their respective jurisdictions: global affairs (canada), ministère des relations internationales et de la francophonie (québec), intergovernmental affairs (nunavut) and the ministry of foreign affairs (greenland and denmark). the choice of these seven public servants was made by these respective governmental departments after an initial enquiry by the researchers: they were deemed to be the most cognizant about cross-border cooperation in this region by their organizations. these eight participants, with the exception of the elected representative interviewed, were not in a political role and could not propose such an initiative. however, we presume that they reflect the dominant perceptions, interests, and priorities in their respective departments. the interviews were conducted via zoom from february to june 2022, and all participants were asked the same set of five questions in a semi-structured interview format. participants were questioned about the potential for the creation of an eastern naa-specific forum as well as limitations and opportunities to further cooperation in the sub-region. answers were then transcribed and analyzed using nvivo software. the codification used grounded theory methodology (e.g., glaser & strauss 1999; suddaby 2006). on the basis of the content of the interviews, the interviewees’ statements and answers were first categorized into two broad categories: positive critiques (encoded as [potential]) and negative critiques (encoded as [critiques]) about the potential creation of an naa cooperative forum. after the completion of all interviews, sub-codes were attributed by themes to reflect opinions and understandings in each broad category (table 1). the sub-codes describe the statements made by the respondents and categorize them in order to best respond to the research question: is a forum of cooperation possible in the eastern naa? in a yes-or-no type of answer, the broad categories [critiques] and [potential] and their sub-codes aim to provide detail about the reasons supporting either answer. each sub-code had a prevalence of use; some had a match in only one or two interviews while others were prevalent across all interviews, indicating the importance of the theme (table 1). in a grounded theory methodology manner, the sub-codes were developed through the interviews; the goal here was not to categorize our interviews in pre-conceived categories but to build the categories through the answers given in the interviews, thereby allowing us to report most truthfully on the impressions, opinions, and analysis of our respondents. table 1 answer codes derived from the interviews. asterisks mark the most prevalent sub-codes that emerged when the interview material was coded. broad code categories sub-codes potential (positive) potential—context—positive signal* potential—boundaries potential—comparison* potential—government level potential—involvement* potential—purpose* critiques (negative) critiques—added value—comparison* critiques—capacity* critiques—boundaries—competences* critiques—added value—purpose critiques context—negative signal critiques—political will results and discussion potential and nature of a cooperative forum the eastern naa is a sub-region that is part of a broader ensemble. as such, regional pan-arctic governance institutions (e.g., arctic council) play an important role for arctic governments and administrations and were discussed by all participants. the existence of established arctic cooperation organizations, forums, and venues poses a double-edged sword for the establishment of a potential naa-specific cooperative forum. indeed, making a comparison between the existing cooperative forums—such as the arctic council—has been used both as a critique and as a proof of need and potential: the sub-code “critique—added value—comparison” was linked 20 times, while its opposite, “potential—comparison,” was linked 15 times in the combined six interviews. this indicates that views are split on the added value that such a forum would bring to governance. the representatives of the governments of québec and denmark had marked doubts about the creation of a new cooperative forum because of the already existing working presence of similar cooperative structures: a new structure did not seem to generate sufficient added value and would be redundant given the arctic council (for québec and denmark) and (for québec) also the arctic circle assembly. these two subjects suggested that relationships between greenland and canadian jurisdictions can already happen and be strengthened in these existing cooperative venues. the case of québec is interesting as this canadian province values its independence and distance from the federal government. therefore, the creation of a new forum would provide a new venue to reinforce regional cooperation and deploy an autonomous international policy. however, the representative treated such a possibility in a rather pragmatic fashion: if existing structures are already in place, and they work well, why not simply use them to foster cooperation with naa jurisdictions? the representative of the government of québec was not opposed to the creation of a new cooperative structure, but he believed this structure should be inserted into an already-existing forum, such as the arctic circle assembly. this skeptical opinion was balanced by other respondents who perceived great potential in a new cooperative forum: this enthusiastic camp consisted of representatives of the governments of canada, nunavut and greenland. our participants from the government of greenland, the government of nunavut and the government of canada all perceived great potential benefits in the creation of such a forum. the canadian official made a comparison with the barents council and the council of baltic sea states, pointing at welcomed precedents. the official from the government of nunavut official expressed the opinion that agreements and memoranda of understanding already in place between nunavut and newfoundland-and-labrador as well as greenland would facilitate further collaboration. a similar observation was also raised by the government of greenland official: joint ventures between greenlandic entities and canadian partners were offered as illustrations of shared interests. further, such a cooperative venture would be welcomed by both the government of greenland official and the greenlandic elected representative, as greenland is in the process of attempting to strengthen ties with north american partners. westward partnerships are perceived as valuable complements to greenland’s already well-established collaborations with nordic countries. the impact the russian invasion of ukraine may have on such an initiative is unclear. western sanctions related to the arctic mostly consisted of suspending the activities of the arctic council. to assess this possible impact, we focused on the sub-code “critique—political will.” this sub-code was detected nine times in three interviews—of the representatives of the governments of canada and denmark and of the greenlandic elected official. for example, the government of denmark official expressed reservations about creating new forums while the activities of the arctic council are suspended as there is an imperative to avoid signalling a further decline in the relevance of the arctic council. here again, however, its opposite sub-code “potential—context—positive signal” was linked 14 times to three interviews—of the representatives of the government of canada and greenland and the greenlandic elected official. the government of canada official perceived no connection between establishing new forums and the arctic council hiatus: new cooperative initiatives can be spearheaded without having detrimental effects on the arctic council’s legitimacy. likewise, the greenlandic elected representative stressed that the suspension of arctic council activities rendered people-to-people connections and cultural ties even more salient. in the view of this interviewee, reductions in contact between northern inhabitants can only generate negative outcomes for greenland. the nature of this potential cooperative forum is also for up for debate: what issues would this forum tackle? questions related to agenda setting are indissociable from concerns about constitutional boundaries and the distribution of powers in the different jurisdictions under study. while further cooperation is needed, as reasserted by all respondents, this cooperation cannot impede on existing mandates determined by respective constitutions. constitutional boundaries delimit what is within the state’s jurisdiction or the sub-national units’ jurisdictions. the eastern naa is characterized by two different modalities for the distribution of competencies. in canada, the powers of the provinces (e.g., québec) differ from competencies held by territories (nunavut). also, greenland enjoys extensive autonomy compared with northern territories in canada. similarly, those jurisdictional boundaries and the difference in political-legal powers between, for instance, the territory of nunavut and greenland, posed an issue according to the representative of nunavut in the determination of the potential naa cooperation agenda. issues discussed at such a cooperative forum would need to be aligned on competencies shared by all governments in the region. governance structures, because of their multiplicity in the region, pose a legal and constitutional boundary issue for which clear guidelines would have to be detailed. the representative of the government of denmark also expressed concern for respecting constitutional boundaries: foreign policy and security, two controversial issues, are within the constitutional boundaries of the danish state. hence, a potential naa cooperative structure cannot impede these competencies. the representative of the government of greenland also made this distinction very clear: military, defense, and security matters would have to be off the discussion table as these issues are not the prerogatives of the government of greenland. issues that could be perceived as bordering on these competencies, such as coast guard capabilities and coordination, were also perceived as problematic for such a forum. proponents of a new forum of cooperation in the eastern naa zeroed in on specific issues to highlight the added value that such an initiative might bring forth. for example, the representative of the government of canada strongly emphasized “the very high potential” for such a regional forum, citing a great need to reinforce commercial and people-to-people ties. the greenlandic elected representative shared this opinion, putting forward regional cultural ties as well as trade; similar priorities were mentioned by the representative of the government of greenland. greenland’s government official highlighted how greenland has had contact with canada “for decades” and saw no “problem for cooperation with neighboring administrations.” the potential for establishing a regional forum—focused on trade and cultural ties—appeared to be split in half: either the existence of current arctic cooperation structures was seen to hamper the need for creating a new structure, or their existence was seen as proof that more cooperation is needed. all respondents mentioned trade and people-to-people ties as aspects of regional cooperation within their respective constitutional boundaries. the representative of the government of canada prioritized trade and commerce as well as family links and cultural development while maintaining that the chosen topics of enhanced regional cooperation “[should] be driven by the communities themselves.” the representative of the government of greenland opened the door to the many possibilities while making clear that defense and military issues cannot be considered as they are not within their jurisdictional rights. “commercial issues, […] social issues, […] education, culture” were among the avenues mentioned for possible further cooperation and are therefore potential avenues of choice for the establishment of a new regional forum. the representatives of the governments of nunavut and québec both emphasised the need for greater regional cooperation on marine protection; the representative of québec in particular put forward the need for greater scientific coordination and cooperation. trade, for instance, in the commercial areas of hunting, mineral extraction, and digital infrastructures, was mentioned as a potential avenue for regional cooperation by the representatives of greenland, nunavut, and canada and by the greenlandic elected official. the elected official also made clear the need for regional cultural exchanges: “i think it would be very interesting to focus much more on the cultural perspective but also the people-to-people perspective.” therefore, there appears to be a consensus that trade and cultural people-to-people ties are, firstly, within the necessary constitutional boundaries and are, secondly, issues of great importance across the borders for which greater cooperation and exchange are in demand. the representative of the government of denmark did not make suppositions about the potential issues that would be most conducive for regional cooperation, instead emphasizing that regional actors and administrations should be the ones deciding on this. the government of denmark added that it is imperative that any cross-border cooperation structure or strategy be designed by the regional actors themselves, referring to greenland specifically. the sub-code “potential—purpose” had 25 references in five interviews (all but the representative of the government of denmark), making it the most prevalent sub-code across all interview responses. there is no doubt that furthering naa cooperation was of interest and that there was a perceived need to further collaboration; the lack of cross-border cooperation was seen by most interviewees as having negatively impacted communities and peoples. the comment made by the representative of the government of greenland is important in this context: “many of these challenges from moving from the traditional society to the modern society—the traumas, the forced development—that we have seen since back in the 1950s […] these things that have been built with could be something that might be a good idea to discuss between kallaalit inuit and inuit in canada.” the listing of areas for further cooperation, such as the arts, including film and music, mentioned by the greenlandic elected official, echo this sentiment. there was a perceived need for cultural rekindling: “we look like each other and their family members. to that extent, i think that art can really help us create ties between countries.” cross-border cooperation was also thereby seen as a way to address some of the wrongs of colonization, and an naa forum or structure could constitute a venue to discuss a locally relevant reality and to find ways to remediate past wrongs and to reconciliate. furthermore, the representative of the government of nunavut emphasized “fisheries, tourism, including cruise ships, transportation links, both air and sea” as potential areas in need of further reinforced cooperation. in addition to marine protection, arctic security is also an area that could see increased regional cooperation, according to this representative. security, however, does not fall within the constitutional remit of the territory. the fact that security was mentioned as an area necessitating greater regional cooperation does call into question the role and place of national governments in a potential naa forum. such an issue could bring forth the possibility that a new cooperative structure could include both national and sub-national governments and tackle a broader array of issues. limitations and obstacles probing past the widespread support for further cooperation, we interviewed participants about the perceived obstacles and limitations of creating a cooperative forum in the eastern naa. three sub-codes, “critique—added value—comparison,” “critique—boundaries—competences” and “critique—capacity,” stand out with the most references within our sample (20, 23, and 18 references, respectively). we addressed the first sub-code in the first section of this article: the government of québec and denmark questioned the added value of this new forum. the second sub-code, “critique—boundaries—competences,” had 23 references in five interviews and was the second only to “potential—purpose” as the most frequent sub-code. therefore, while there was a very high potential in terms of purpose, that is, there was a demand for a higher level of regional cooperation, the different competences of the governments of the region and the constitutional boundaries of what could become a subject of cooperation could hamper this potential. firstly, concerning the different levels of government competences, the representative of the government of denmark questioned how such a forum would operate in the face of the differences in levels of competence of the different regional administrations: “i believe that the government of greenland has much more competence than the government of nunavut […] you would have uneven players sitting at the table.” the representative of the government of nunavut highlighted the same potential issue: “our governance structures are so different that there’s a lot of education needed to know, […] who are the authoritative bodies?” “dealing with different organizational structures and hierarchy,” as the representative of the government of nunavut put it, summarizes the main political and administrative limitation of such a regional forum: what each administration can do varies from actor to actor. whereas the representative of nunavut highlighted how the main negotiating partner in nunavut would be the government itself, in greenland two levels of governance would likely be involved: the municipal as well as the higher-level government. the representative of the government of greenland joined this position by highlighting the potential for greenland to become independent, something that is not in the cards for nunavut, nunavik (northern québec) or newfoundland-and-labrador. the 2009 act of self-government granted the government of greenland the possibility of establishing its own trade agreements—as it did with the uk—which is within their full jurisdiction. in short, the greenlandic government representative concluded that “there is a difference in terms of sovereignty and autonomy between the provinces and the territories of canada and the government of greenland.” on the topic of the level of governance, the representative of the government of québec did not necessarily see this as problematic for regional cooperation but rather framed it as a domestic affair for each partner. the idea was that cooperation as a whole is going very well despite these differences, so these differences should not be an impediment to further collaboration. in addition, the constitutional boundaries of each regional governments also dictate what can or cannot be part of regional discussions. on this point, the representatives of both denmark and greenland expressed similar views. coast guard and military issues were off the discussion table for both as these are not within the constitutional boundaries of the government of greenland, while business cooperation, education, culture and social issues would be the preferred topics of a regional cooperation forum. these answers suggest that greenland is interested in expanding its para-diplomatic activities without the presence and support of the government of denmark. focusing solely on issues for which the government of greenland has sole jurisdiction would fulfill this purpose. however, the representative of nunavut mentioned several times the potential for naa cooperation on arctic security and marine protection. but, on account of the lack of a “consistent history of cooperation with all these regions and dealing with different organizational government structures and hierarchy” (including constitutional boundaries), the nunavut representative thought that was unclear what potential there really is for naa security cooperation, even though this is a major political topic in the region. in september 2021, former greenland minister for foreign affairs, pele broberg, commented during an interview with the newspaper sermitsiaq on greenland’s ambition to establish its own coast guard following the icelandic model, that is, a civilian coast guard rather than one subordinated to the military (wenger 2021). broberg has since then been replaced as minister of foreign affairs and is now the minister of business and trade. arctic security is a controversial topic that would bring forth circumpolar and international consequences for actors such as the us and russia. on the topic of security, the greenlandic elected official mentioned the devastating effects of the russian war in ukraine, which has negatively affected regional cross-border cooperation—especially for civil society cooperation—and said that it would “take time to build up trust after the war.” the other sub-code that stood out centered on capacities: would necessary resources be mobilized to bring this initiative to fruition? this line of limitations was expressed by all participants and touched on some of most fundamental dynamics influencing northern communities. for example, the representative of the government of canada pointed to limited accessibility, both physical and virtual, as posing a significant limitation to the development of such a regional cooperation forum. poor digital infrastructures render any virtual format or structure difficult to sustain: the lack of high-speed connectivity in the north limits virtual contacts and modes of participation. broadband deficiency hampers commerce, cultural development and communication, which are vital to the establishment of regional cooperation. moreover, great distances between jurisdictions and the limited options in terms of transportation connecting communities carry the potential to impede cooperation. the representatives of the governments of canada, nunavut, and greenland, as well as the greenlandic elected official, all responded to the question of technical limitations by highlighting the lack of air or sea cargo connection between north-eastern canada and greenland. the scheduled airlink between greenland and nunavut has been discontinued, and at present there is no direct, rapid mode of transportation. the representative of the government of greenland joined the critique regarding the lack of infrastructures as an important limitation, stating that it is expensive and time consuming to travel in the region: “physically we are extremely close, of course in the high north. but it’s very hard for us to say hello to each other.” this lack of infrastructure joins a larger potential limitation in terms of capacity: the costs of establishing and maintaining such a new forum is: “always down to resources. it’s a matter of money, it’s a matter of time” (greenlandic elected official). the limited resources, as also mentioned by the representative of the government of denmark, significantly dampen the benefits of establishing a new naa forum: does the establishment of a new forum respond to a need and demand that could not be fulfilled by using most cost-efficient venues, such as existing arctic cooperation structures? the representative of the government of québec responded by maintaining that creating a working group within an existing structure, such as the arctic council or the arctic circle, might be more efficient, in terms of resources and time, than creating a new forum. the greenlandic elected official also leaned more toward this opinion: “i’m not sure if we necessarily need forums to do that or if we just need to have a political focus on collaborating with each other.” a final notable limitation to the creation of a new naa forum is political will, which collected nine sub-coded references. “would they think it’s a great idea?” (representative of the government of denmark) essentially summarized the issue at hand: there needs to be a political will to drive the creation of a regional, low-level, practical cooperation regarding cross-border issues. this political will must come from the top as financial resources must be mobilized for cooperation to happen, as highlighted by the greenlandic elected representative who was interviewed. a similar dynamic is at play in canadian jurisdictions. in the context of canada, finding funds for the establishment of a new cross-border forum might prove to be a long and arduous process, according to the representative of the government of canada. maintaining both capacity and political will on a long-term horizon is also very difficult: support for one-off events is much easier to obtain while funding long-term initiatives and structures requires a more serious commitment. structure and membership an eastern naa forum would involve both national and sub-national governments. as such, the role that respondents foresaw national governments playing in such an initiative was intriguing. national governments can assume different roles depending on the institution. for example, the bear elaborated a structure comprising two bodies, one convening national governments and another strictly for sub-national administrations (barents regional council). the government of canada plays a pivotal role in the beaufort sea partnership, convening stakeholders and offering administrative and logistical support. other sub-regional arrangements have a mix of national and sub-national governments interacting together, such as the west nordic council, with iceland, greenland, and the faroe islands as members. so, what about the role of national governments in a possible eastern naa forum? there was a clear consensus on this question. both the government of canada official and government of denmark representative acknowledged that the leading role must be filled by sub-national governments: they must be at the center of the process, developing the agenda and agreeing on priorities. the representative of the government of nunavut saw the primary leading role as sub-national in nature as well, emphasizing that talks leading to a devolution process are underway in nunavut while greenland already have self-rule in place. this level of decentralization opens the door for more direct involvement by sub-national governments in a wide array of issues. however, the representatives of the governments of canada and nunavut also recognized the possibility of governmental involvement in cases of hot issues or “on an ad hoc basis if there were things of a national importance or priority that they need to be roped in” (representative of the government of nunavut). here again, the government of canada was seen in a supporting role, rather than driving the process, a position that would complement and help local stakeholders fulfill their objectives. as such, the government of canada perceived its potential role as one of convener, bringing interested parties together by facilitating the organization of events and using its political relationships and influence in global affairs canada headquarters and its embassy in copenhagen. additionally, the department of global affairs of the government of canada could potentially coordinate the actions and participation of other federal departments in such a cooperative venture. for the greenlandic elected official, self-determination was primary. the importance of self-determination was echoed by the representative of the government of greenland, mirroring the position of the danish counterpart: the government of greenland would have the leading—sole—role in the creation and maintenance of an naa cooperation forum. because the importance of staying within constitutional boundaries was raised multiple times by both actors, the potential naa cooperation forum would remain within the jurisdiction boundaries of the government of greenland. as such, the involvement of the danish government would not be required and the representative of the government of denmark did not envisage participating in any form in an naa cooperation forum. the danish official used the example of the west nordic council to illustrate that greenland can be active in some multilateral initiatives without the involvement of the danish state: ‘low-politics’ issues are conducive to this acceptance. the representative of the government of denmark also highlighted that the resources for the creation and maintenance of such a forum would have to come out of greenland’s budget. concerning federal or national governments’ involvement or the lack thereof, the representative of québec had an interesting position, echoed by the representative of the government of nunavut: the nature of arctic cooperation is centered on cooperating. the exchanging nature of regional relations makes the role of communities and individuals central to cooperation. the most noticeable difference is the central, leading role of indigenous communities and governing powers. while not responding explicitly to the issue of federal involvement, the representative of the government of québec noted that the leading role to establish and maintain an naa cooperation forum would have to be sub-national and local. however, the official of the government of québec also added that the relationship with the government of canada is positive and productive, citing the agreement that led to the canada–inuit nunangat–united kingdom arctic research programme as an example. collaboration is possible as long as competencies are respected. similar to the role of national governments, the presence of civil society does not appear to be controversial: civil society considered by all respondents as essential to the workings of cross-border regional cooperation. for example, the greenlandic elected representative stated that “what first comes to mind is of course indigenous peoples, non-governmental organizations, civil societies and especially the inuit circumpolar council [which] is so important for us in greenland. i think we are going to see this strengthened in the years to come.” the key role of arctic and northern civil society was highlighted by the representative of the government of canada, who stated that projects must be anchored in local realities and demands: credibility is built through civil society. building credibility for an naa cooperation forum would come through the involvement of civil society, which would bring their expertise to the table. the representatives of the governments of nunavut and greenland both referred to the involvement of fishermen and hunters’ organizations as well as private enterprises: chambers of commerce, tourism bodies, and different corporate associations could participate in this type of initiative. the involvement of inuit organizations—such as the aforementioned inuit circumpolar council, as well as nunavut tunngavik incorporated or qikiqtani inuit association—was seen as fundamental also in terms of reconciliation: “in this day of reconciliation and to be very inclusive of indigenous participants of the region, that would be wise to think from the onset” (representative of the government of nunavut). the inuit circumpolar council was the most often mentioned civil society organization. the organization was cited by the government of greenland official and greenlandic elected representative as an example of an organization collaborating and cooperating with governments to deliver tangible results to communities. civil society organizations were presented as highly capable of contributing and generating positive outcomes for people. in a similar vein, the representative of québec believed that civil society is already to be found within existing cooperation structures in the arctic, such as the arctic council, where organizations such as the world wildlife fund and youth organizations are not only a reality but also a necessity: “we cannot only work with governments. i think that it’s essential to involve everyone because these are topics that concern us all. we cannot arrive at solutions that only concern the governments” (representative of the government of québec, translated). while the context of the representative’s comments was scientific collaboration, this represents the tone of thoughts on larger, overall, cooperation in the arctic: strictly hierarchical relations are not sustainable, nor do they echo the lived realities of the arctic, where indigenous knowledge is fundamental both to further scientific research but also for social and political relations within the region. indigenous peoples as well as non-governmental organizations and private enterprises constitute key actors in the region and must be part of every cross-border regional talk. the representative of the government of nunavut, informed by the accessibility difficulties in the farnorth, also saw civil society as holding an outreach role in order to build bridges and ties both within and between regions. while the involvement of civil society therefore does not seem to be controversial, the representative of denmark emphasized the need to understand the purpose of both the cooperation forum and its participants: if civil society were to be involved, what would its role be—to advise or to practically implement policies? the official of the government of canada also raised concerns about capacities: civil society organizations must be given the capacity to participate and meaningfully contribute to the work of the forum. these organizations are often focused on day-to-day activities and programmes and possess very little resources to partake in the activities of a multilateral organization. conclusion: toward an eastern naa forum? our main research question was geared toward understanding whether there is a will to establish a forum of cooperation in the eastern naa. a second area of inquiry was to identify and understand the incentives and obstacles to institutional cooperation in the region. the interviews offered insights into officials’ perceptions of cooperation in the eastern naa. a majority of the officials interviewed believed that a new forum of cooperation in the region would be highly desirable, on account of shared interests, common identity and cultural affinities. consensual positions were also found regarding the central role that civil society would play in a new cooperative venue and about how sub-national governments would assume a leading role to spearhead the initiative. there was general agreement among those interviewed on the issues that this prospective forum might address: trade issues, cultural ties, education and environmental protection were all raised by several participants, with the first two being the most popular. all issues are within the sphere of ‘low politics,’ follow jurisdictional lines and represent a positive-sum game. this is consistent with higginbotham & spence’s findings that naa decision-makers have a “desire to continue to work together” while stressing “the importance of identifying practical activities for collaboration” (2018: 5). on the other hand, the representatives of national governments who were interviewed did not perceive their roles similarly. the official of the government of canada indicated that the federal government could play a role of support and convener to sub-national governments. the government of denmark official perceived such forum as an initiative not involving denmark: greenland would participate without additional support from the central government. additionally, the respondents from the governments of québec and denmark did not think that a new forum in the region would add value to the forums and institutions already in place in the arctic. through these interviews, we heard about similar obstacles to cooperation for the eastern naa as reported by higginbotham & spence (2018) for the naa as a whole. limited financial resources is still the main limitation to further cooperation in the eastern naa: this is consistent with other findings on arctic para-diplomacy, where sub-national governments have limited options to be active diplomatically (landriault et al. 2021). a major irritant to cooperation is the lack of transportation infrastructure connecting these territories. the absence of a nuuk–iqaluit air connection was raised by several participants and presented as a key node missing from efforts to strengthen collaboration between greenland and northern canada. looking at multilateral forums present in the arctic region, there is a clear idea as to which issues should animate this multilateral cooperation, contrary to the northern forum. a dominant perception was that the moment was ripe to increase collaboration between greenlandic and canadian partners: the main issue remained how to transcend physical or infrastructure barriers, such as low connectivity and deficient transportation infrastructures. the issue of limited financial resources is also left unresolved, and there is no obvious driving force that could lead the creation of such forum, as norway did for the bear cooperation in the early 1990s. the financial support of the government of canada could help supplement financial constraints shared by northern jurisdictions. the presence of a federal government willing to act as convener could lower the costs of international diplomacy for a territory characterized by limited financial resources. following these interviews, it is difficult to pinpoint one government that could spearhead alone this new forum of cooperation. however, two entities seemed more enthusiastic about such a possibility: the governments of nunavut and greenland. the latter is orienting its international policy toward furthering ties with north american governments and administrations. given the territory’s drive to complete independence, this type of forum could prove to be a statement of diplomatic motivation and ambition, tilting toward proto-diplomacy, an international policy to prepare the terrain for complete autonomy. the government of nunavut perceived shared interests into cooperating with neighbouring canadian jurisdictions and greenland. the presence of a federal government willing to act as convener could lower the costs of international diplomacy for a territory characterized by limited financial resources. with cultural affinities, an explicit desire to further collaboration and very little ideological opposition, there is genuine willingness to the establishment of a cooperative venue in the eastern naa. it remains to be seen if barriers to cooperation can be removed to tap this potential. acknowledgements the authors would like to thank the two reviewers for their helpful comments. references ackrén m. & jakobsen u. 2015. greenland as a self-governing sub-national territory in international relations: past, current and future perspectives. polar record 51, 404–412, doi: 10.1017/s003224741400028x. akimov y. 2021. arctic paradiplomacy of the republic of sakha (yakutia): the impact of federalism, nationalism, and identity. in m. landrault et al. (eds.): mapping arctic paradiplomacy. pp. 77–98. milton park: routledge. anderson s.v. 1963. negotiations for the nordic council. nordic journal of international law 33, 23–33, doi: 10.1163/187529363x00024. bailes a.j. & ólafsson k.þ. 2017. the eu crossing arctic frontiers: the barents euro-arctic council, northern dimension, and eu–west nordic relations. in n. liu et al. (eds.): the european union and the arctic. pp. 40–62. leiden: brill nijhoff. caddell r. 2022. strength in numbers? the nordic ministerial and parliamentary groupings as observers in the arctic council. in n. sellheim & d.r. menezes (eds.): non-state actors in the arctic region. pp. 133–152. berlin: springer. glaser b. & strauss a. 1999. discovery of grounded theory: strategies for qualitative research. milton park, uk: routledge. henriksen a. & rahbek-clemmensen j. 2017. the greenland card: prospects for and barriers to danish arctic diplomacy in washington. danish foreign policy yearbook 1, 75–98. higginbotham j. & spence j. 2018. the north american arctic: energizing regional collaboration and governance. waterloo, canada: centre for international governance innovation. landriault m., chater a., rowe e.w. & lackenbauer p.w. 2019. governing complexity in the arctic region. milton park: routledge. landriault m., payette j.-f. & roussel s. 2021. conclusion–limitations and opportunities in arctic paradiplomacy. in m. landriault et al. (eds.): mapping arctic paradiplomacy. pp. 217–223. milton park: routledge. larsen k. 1984. scandinavian grass roots: from peace movement to nordic council. scandinavian journal of history 9, 183–200, doi: 10.1080/03468758408579041. nielsson e.t. 2013. the west nordic council and its arctic engagement. the arctic yearbook 2013 2. accessed on the internet at https://arcticyearbook.com/arctic-yearbook/2013/2013-briefing-notes/63-the-west-nordic-council-and-its-arctic-engagement on 7 december 2022. suddaby r. 2006. from the editors: what grounded theory is not. academy of management journal 49, 633–642, doi: 10.5465/amj.2006.22083020. tsui e. 2016. revisiting the northern forum: lessons from alaska’s involvement. the arctic yearbook 6. accessed on the internet at https://arcticyearbook.com/arctic-yearbook/2016/2016-briefing-notes/204-revisiting-the-northern-forum-lessons-from-alaska-s-involvement on 8 march 2023. wenger m. 2021. an own coast guard for greenland? the polar journal. accessed on the internet at https://polarjournal.ch/en/2021/05/25/a-own-coast-guard-for-greenland/ on 7 december2022. zimmerbauer k. 2013. unusual regionalism in northern europe: the barents region in the making. regional studies 47, 89–103, doi: 10.1080/00343404.2011.644236. por_005.fm polar research 26 (2007) 37 – 47 © 2007 the authors 37 blackwell publishing incmalden, usaporpolar research0800-03952007 blackwell publishing ltd? 20072613747original articles the sipunculan fauna of svalbardm. k&mu2;dra & g.v. murina the sipunculan fauna of svalbard monika k dra 1 & galena v. murina 2 1 institute of oceanology, polish academy of science, sopot, poland 2 institute of biology of the southern seas, academy of sciences, sevastopol, ukraine ę abstract this study presents the species of sipuncula collected in the svalbard area (74–81 ° n and 10–35 ° e) in the summer seasons from 1996 until 2005 at depths ranging from 40 to 2553 m. the faunistic analysis of the material (1056 specimens from 251 stations) resulted in a total of six species and one subspecies, belonging to two families (golfingiidae and phascolionidae). one species, golfingia vulgaris , has not been reported previously from svalbard waters, and increases the total number of sipuncula taxa known from svalbard to nine. three species dominated the collected material: g. vulgaris (53.5% of all specimens found), g. margaritacea (19.3%) and nephasoma diaphanes diaphanes (15.5%). the study shows that compared with other northern regions, svalbard hosts a relatively rich sipunculan fauna, which is most similar in species composition to the sipunculan fauna found in asian arctic waters. an easy-touse identification key to svalbard sipuncula species is given to aid field researchers in the identification of this often overlooked taxon. keywords sipuncula; diversity; distribution; svalbard. sipuncula is a phylum of exclusively marine worms. according to recent revisions, it consists of two classes, six families, 17 genera and about 150 species and subspecies (cutler 1994). sipunculans inhibit most marine habitats from intertidal zones to abyssal depths (cutler 1994). sipuncula are predominantly tropical and subtropical worms (75% of the species). boreal species account for 19% of the species, and 3% are bipolar and cosmopolitan species. another 3% occur in arctic, antarctic and temperate–cold waters (murina 1975). sipuncula are mostly deposit feeders living in various substrata, mainly containing mud, silt and sand. some species may seek a protective shelter in molluscan shells, polychaete tubes and foraminiferan tests (murina 1984). sipuncula are very often neglected in ecological studies, although they may play a considerable role in the bioerosion of coral reefs and soft rocks (cutler 1968; stearley & ekdale 1989), as food for fish, gastropods and occasionally people (kohn 1975), and probably as bioturbators (murina 1984; romero-wetzel 1987). in arctic fjords sipuncula may play an important role in macrobenthic communities and are among the dominant taxa (e.g. wf sl awski et al. 1988; wl odarska-kowalczuk & pearson 2004; wl odarska-kowalczuk et al. 2004), but usually they are identified only to the phylum level. even though a number of publications on sipuncula from arctic areas have been published (théel 1905; wesenberg-lund 1930, 1933, 1934, 1938, 1955; murina 1977), almost all information on sipuncula in svalbard comes from studies conducted at the beginning of the last century (théel 1905; fischer 1895, 1914, 1922, 1929). some remarks on sipuncula are made in gulliksen et al. (1999), although their work should be treated with caution as their information on svalbard species, including sipuncula, is mostly based on the early published sources, which may be of questionable quality. further information on sipunculans (mainly concerning species found in asian arctic shelf seas and the barents sea) has been published by murina (1977). the main aim of this article is to present a synopsis of the composition and distribution of the sipuncula in the waters of the svalbard archipelago based on our own samples and published data. species composition of sipuncula found in the svalbard area is compared with their distribution in the north atlantic, arctic seas and the waters around antarctica. an identification key of svalbard sipuncula species is given to aid field researchers in the identification of this often overlooked taxon. correspondence monika k dra, institute of oceanology, polish academy of science, powsta ców warszawy 55, 81-712 sopot, poland. email: kedra@iopan.gda.pl doi:10.1111/j.1751-8369.2007.00005.x ȩ n′ 38 polar research 26 (2007) 37 – 47 © 2007 the authors the sipunculan fauna of svalbard m. kędra & g.v. murina material and methods the svalbard archipelago is located between 74 and 81 ° n and between 10 and 35 ° e. it is influenced mainly by two water masses, the warm west spitsbergen current (temperature above 2 ° c and salinity of 35 psu (practical salinity unit)) and the cold east spitsbergen current (from − 1.5 ° c to 1 ° c, 34–35 psu) (loeng 1991; beszczynskamöller et al. 1997). the west spitsbergen current is the northernmost extension of the norwegian atlantic current and keeps the area free of ice throughout most of the year. the east spitsbergen current carries arctic water between spitsbergen and franz josef land, and then southward along the eastern coast of spitsbergen (loeng 1991). the svalbard coast is subjected to ice scour from drifting ice in the summer months, whereas fast ice forms in the inner fjords in winter (wf sl awski et al. 1988; svendsen et al. 2002). material was collected during cruises with the rv oceania (1996 to 2005) and rv polarstern (ark xvi and ark xix expeditions, deep-sea samples). samples were mostly taken in the fjords of kongsfjorden and hornsund but were also taken in van mijenfjorden and adventfjorden. additional samples were taken in magdalenefjorden, storfjorden, erik eriksenstretet and near kong karls land (material provided by akvaplan-niva, polar environmental center, n-9296, tromsø, norway) (fig. 1; table 1). a total of 251 stations were sampled, 450 samples were taken (fig. 1) and 1056 specimens were identified. most (378 of 450) samples were taken with a van veen grab (0.1-m 2 catch area), the remainder were taken with either dredges (74 samples) or box corers (14 samples). material was washed on a 0.5-mm sieve and fixed in a 4% buffered formaldehyde and sea water solution. all organisms were later sorted and sipuncula specimens were picked. the taxonomic nomenclature is adopted from cutler (1994). the material is deposited at the institute of oceanology, polish academy of science, in sopot, poland. cluster analysis (using group–average linking) was performed on the presence/absence data. to perform the cluster analysis, 23 species were included in total, of which nine were reported from antarctica only. the detailed matrix with information on species occurrence in different polar areas is presented in fig. 2. the similarities between samples were calculated using the bray-curtis index. multivariate analyses were performed with the use of the primer package version 6 (clarke & warwick 2001). results sipuncula specimens were not very numerous and were found only at 115 of the 251 (45.8%) stations. at some stations sipuncula species represented a significant part of the benthos samples and were among the dominant species. especially rich were samples collected at the deep figure 1 location of sampling sites in the waters off svalbard. 20° 30° e10°0° spitsbergen longyearbyen ho rns und ko ngs fjor den svalbard 0 100 km sto rfjo rde n eri k e riks ens tre tet ko ngs ka rls lan d ma gda len efjo rde n ad ven tfjo rde n va n m ijen fjor den ha usg art en number of samples taken at each site: 1 3 4 50 >50 nordaustlandet 80° 78° 76° n m. kȩdra & g.v. murina the sipunculan fauna of svalbard polar research 26 (2007) 37 – 47 © 2007 the authors 39 sea sites, at hausgarten, (a maximum of 404 specimens per 1 m 2 were found) and in kongsfjorden (a maximum of 840 and 520 specimens per 1 m 2 were found at the two sites sampled). nevertheless, at most of the stations we found only a few specimens or a single specimen. table 2 shows the distribution, type of substrata on which particular species were found and abundances of sipuncula species in svalbard waters. seven species have been reported from the svalbard archipelago in the past (table 3). we have recognized seven taxa: six species and one subspecies, belonging to two families (golfingiidae and phascolionidae), of which two have not been reported previously from the svalbard area ( golfingia vulgaris and nephasoma diaphanes corrugatum ). in the collected material three species dominated among the sipuncula fauna found in this study: g. vulgaris (53.5% of all specimens found), g. margaritacea (19.3%) and n. diaphanes diaphanes (15.5 %). g. elongata was the rarest species, occurring at only seven stations (nine specimens—less than 1% of all specimens found). for each species found in our material some remarks on their distribution and biotope are provided. table 4 contains the information on the depth distribution in the world ocean, the north atlantic, the arctic and svalbard waters (this study). golfingia margaritacea margaritacea (sars, 1851) this cold water and cosmopolitan species is widely distributed. many reports are from cold and temperate (boreal) regions, especially in the shelf and bathyal zone. it has rarely been found in the tropical and subtropical zone. it occurs in the atlantic, arctic and antarctic oceans (from 80 ° n to 78 ° s) as well as in the pacific ocean (above 30 ° n and 30 ° s), but it is unknown in the indian ocean. it inhabits mud and sand/gravel bottoms, and red clay in the abyssal (gibbs 2001). golfingia vulgaris vulgaris (de blainville, 1827) this cold water and cosmopolitan species is encountered extensively in the world ocean, particularly in the northeastern atlantic, including the waters off greenland, scandinavia and the british isles, as well as in the mediterranean and red seas. its absence from the western atlantic ocean is noteworthy. this species occurs rarely in the arctic zone: there are some reports from the barents, east siberian and chukotsk seas. it usually inhabits silt, mud, different types of sand and clay in deep waters (saiz-salinas & villafranca urchegui 1990). table 1 basic information about cruises and sampling details. cruise information (no. of cruises) area sampling year sampling gear number of stations number of samples % of stations where sipuncula were found rv oceania (10) kongsfjorden 1996–2005 van veen 70 155 52.4 1996; 1997; 1999 dredge 63 63 27.7 hornsund 2002; 2003; 2005 van veen 68 102 22.7 2003 dredge 11 11 57.1 van mijenfjorden 2000; 2001 van veen 10 44 70 adventfjorden 2004 van veen 6 20 66.6 rv polarstern (2) ark xvi & ark xix hausgarten 2000; 2003 box corer 14 14 57.1 akvaplan-niva (1) storfjorden 1996 van veen 3 15 100 kong karls land 1 5 100 magdalenefjorden 3 15 33.3 erik eriksenstretet 2 10 66.6 total (13) 251 450 45.8 figure 2 dendrogram showing the faunistic resemblances in the composition of the sipunculan fauna of various northern polar and subpolar regions: faroe isles (murina & sørensen 2004); iceland (wesenberg-lund 1937b); east greenland (wesenberg-lund 1937a); norwegian sea (murina 1977); barents sea (sirenko 2001); asian arctic shelf seas (sirenko 2001); antarctica (saiz-salinas 1995; saiz-salinas & pagola-carte 1999); and svalbard (this study). 100 80 60 40 an ta rc tic a n or w eg ia n se a ba re nt s se a sv al ba rd as ia n ar ct ic s he lf se as fa ro e is la nd s ea st g re en la nd ic el an d b ra yc u rt is s im ila ri ty 40 polar research 26 (2007) 37 – 47 © 2007 the authors the sipunculan fauna of svalbard m. kędra & g.v. murina table 2 distribution of sipuncula in svalbard waters (number of specimens found in each area) and the substrate types in which specimens were found. k h vm a ee s m kk hg total golfingia margaritacea 11 182 10 1 204 mud g. vulgaris 382 161 1 5 2 2 2 10 565mud, sandy mud, bioturbated mud, clay/mud (30–40% clay) g. elongata 5 5 10 mud and sandy mud nephasoma lilljeborgi 55 55 silty/sandy clay n. diaphanes diaphanes 43 3 1 2 2 113 164 sandy mud, clay, mud n. diaphanes corrugatum 3 2 5 sandy mud, mud phascolion strombus 41 3 2 7 53 sand, muds, sandy silt k, kongsfjorden; h, hornsund; vm, van mijenfjorden; a, adventfjorden; ee, erik eriksenstretet; s, storfjorden; m, magdalenefjorden; kk, kong karls land; hg, hausgarten. table 3 sipunculan species reported from the svalbard archipelago by various sources. species fischer 1895 théel 1905 fischer 1914 fischer 1922 fischer 1929 murina 1977 gulliksen et al. 1999 this study golfingia margaritacea x x x x x x x g. vulgaris x g. elongata x x nephasoma diaphanes diaphanes x x x x n. diaphanes corrugatum x n. lilljeborgi x x x x n. eremita x x x x x n. abyssorum x x x x phascolion strombus x x x x x x x table 4 depth range (m) of sipuncula taxa found in the world ocean (murina 1977; cutler 1994; murina, unpubl. data), north atlantic from 60 ° n to 40 ° n (cutler 1994; murina 1977; murina, unpubl. data), north atlantic > 60 ° n (murina 1977; murina, unpubl. data) and in svalbard waters (this study). taxon world ocean north atlantic 60 °− 40 ° n north atlantic > 60 ° n svalbard min. max. min. max. min. max. min. max. golfingia margaritacea 0 5300 72 4600 8 3230 67 290 g. vulgaris 5 2000 37 248 15 1480 64 374 g. elongata 10 590 0 73 ? ? 79 162 nephasoma diaphanes diaphanes 0 5300 10 4800 a 446 2701 40 2553 n. diaphanes corrugatum 80 5900 n. lilljeborgi 65 2734 40 2200 1912 2553 n. eremita 0 3867 73 515 — — n. abyssorum 95 5300 95 973 — — phascolion strombus 1 4030 9 2090 15 1890 79 390 a in the iberian trench. m. kȩdra & g.v. murina the sipunculan fauna of svalbard polar research 26 (2007) 37 – 47 © 2007 the authors 41 golfingia elongata (keferstein, 1862) this tropical and boreal species is cosmopolitan in the northern hemisphere, in the north-western atlantic (from newfoundland to bermuda and cuba) and northeastern atlantic (from spitsbergen to the iberian peninsula and in the mediterranean sea) and in the pacific ocean (eastern and southern china and vietnam). it is rare in the arctic zone: greenland, spitsbergen and iceland (cutler 1994). it prefers the upper sublittoral (saizsalinas & villafranca urchegui 1990). it often inhabits hard ground, gravel, sand, shelf rock; less often it inhabits silt, clay and mud (cutler 1994; saiz-salinas & villafranca urchegui 1990). nephasoma diaphanes diaphanes (gerould, 1913) this is a cosmopolitan species with widely ranging vertical distribution. it is the most common sipunculan in deep-sea communities (cutler & cutler 1987a). in arctic waters it was reported from spitsbergen, novaya zemlya and the barents sea. this species inhabits silt, sand and mud, and is often found in foraminiferal tests, small polychaete tubes and mollusc shells (cutler 1994). in this study it was usually found in the shelter of foraminiferal tests. cutler & cutler (1986) regarded n. minutum (keferstein 1862) as a hermaphrodite species confined to the north-eastern atlantic. in contrast, n. diaphanes , which is morphologically and anatomically similar to n. minutum , is dioecious and cosmopolitan (cutler & cutler 1986). murina & sørensen (2004) considered n. diaphanes as a junior synonym of n. minutum and agreed with gibbs’ (1975) opinion: “the morphologically similar specimens now regarded as a single species have two distinct forms, a dioecious form found chiefly in deep water, and a hermaphroditic form found on the shore and in shallow water around europe and scandinavia”. accordingly, the name n. diaphanes is used in this paper. nephasoma diaphanes corrugatum cutler and cutler, 1986 this subspecies is widely distributed in the atlantic and pacific oceans, as well as in the mediterranean and red seas. nephasoma lilljeborgi (danielssen and koren, 1880) this species is of arctic/boreal origin. according to cutler & cutler (1987a) it is only known to inhabit the northern deep-sea basins in the far north-eastern atlantic ocean between 70 ° and 80 ° n, and might therefore be endemic to these regions (cutler 1994). it was reported from spitsbergen, greenland, baffin bay, the norwegian coast, the western part of sweden, the eastern part of iceland and the russian seas (the kara, laptiv, east siberian and chukchi seas). it inhabits muds, clay and sandy mud. nephasoma diaphanes often occurred with n. lilljeborgi in the same samples, although n. diaphanes is a more eurybathic species that was found at a wider range of depths (40–2553 m). phascolion strombus strombus (montagu, 1804) this is a cosmopolitan but mainly cold water species that is widely encountered in all oceans (rare findings in the indian sea). it is common in russian arctic seas. it prefers the littoral and sublittoral, penetrates in bathyal and is rare in abyssal zones. usually it inhabits sand, mud and silt, and is often found in mollusc shells and polychaete tubes (hylleberg 1970). in this study it was found sometimes in gastropoda shells and polychaeta tubes. discussion the results of this study show that the svalbard area hosts a relatively rich (for the high arctic region) sipunculan fauna. we increased the total number of sipunculan taxa now known from the svalbard area from seven to nine. cluster analysis of sipuncula assemblages from different regions showed that the sipuncula species composition of the svalbard region is most similar to the one from the asian arctic seas. the sipunculan fauna includes members of the same taxa in both areas except for g. elongata , which has not been reported from the asian arctic seas (sirenko 2001). the barents sea (sirenko 2001) clusters (although not very well) with the other north atlantic areas except for the faroe islands. a relatively low number of sipunculan taxa (six) was reported from east greenland (wesenberg-lund 1937a) and iceland (wesenberg-lund 1937b). the arctic regions are well separated from the antarctic, where twice as many species of sipuncula are found (saiz-salinas 1995; saizsalinas & pagola-carte 1999; cutler et al. 2001) (fig. 2). in general, there is an increase in species richness from high to lower latitudes. this trend has been shown for many groups of marine organisms, both benthic and planktonic (stevens 1989; angel 1996; ormond et al. 1997). even though the paradigm of the latitudinal distribution of species richness is still subject to discussion (gray 2001), sipuncula seem to follow this rule. the phylum is undoubtedly centred in warmer waters, where the great majority (75%) of species is found. the highest 42 polar research 26 (2007) 37 – 47 © 2007 the authors the sipunculan fauna of svalbard m. kędra & g.v. murina species diversity is found in the indo-west pacific and particularly in the indo-malayan archipelago. these regions are thus regarded as the main centre of origin and development of sipuncula (murina 1975). in the atlantic ocean the number of sipuncula species decreases towards higher latitudes, although the decrease towards the south is not as strong as towards the north. in the north atlantic the diversity of sipuncula is highest off ireland (21 species) and in the north sea (17 species). it decreases with latitude to svalbard (eight species) and the asian arctic seas (seven species). even though more species are reported from the antarctic area (16) (saizsalinas 1995; saiz-salinas & pagola-carte 1999; cutler et al. 2001), there is a progressive loss of genera and species along a polar gradient from locations above the antarctic convergence to the high latitudinal antarctic regions (saiz-salinas 1995). the effects of extreme cold temperatures appear to be the main structuring factor, although other, as yet unknown, factors may be of importance in determining this biodiversity gradient (saiz-salinas & pagola-carte 1999). the higher number of sipuncula species in the southern ocean than in the arctic may be caused by the greater age of the former region. antarctica has been isolated for about 40 million years (dunton 1992), whereas the arctic ocean has existed for only 2–3 million years (dayton et al. 1994). the fact that the southern ocean covers a larger area may contribute to its greater species richness. bouchet & waren (1979) supposed that in addition to the effects of age and isolation, the homogeneity and absence of geographic isolating barriers within the arctic abyssal area could result in low species richness. the arctic ocean fauna, located between two major oceans, is young and of mixed origins. repeated pleistocene glaciations were lethal to inhabitants of the arctic ocean and are the reason for the youth of the fauna and its low diversity (dunton 1992). the harshness and relative homogeneity of habitats in the arctic are also common explanations (clarke & crame 1997). sipunculans inhabit all of the seas of the world and are found at all latitudes. the zoogeographical range of many species is difficult to define because of their tolerance of a broad range of temperatures and depths. moreover, many have planktonic larvae that play a very important role in determining their wide geographical distribution (scheltema & hall 1975; scheltema & rice 1990). teleplanic larvae of sipunculans are abundant across entire ocean basins (scheltema 1975; scheltema & rice 1990). ranges appear to be determined by water temperature, bottom topography and water currents (cutler & cutler 1987b). the sipunculan fauna on most oceanic islands appears to include mostly species with wide geographical distributions, and very few endemic species are known (scheltema & hall 1975). however, the potential larval dispersal may be quite different from the realized larval dispersal: many marine species with teleplanic larvae may have more limited ranges than are hypothesized on the basis of their potential for larval dispersal. furthermore, either potential or realized larval dispersal does not necessarily confer genetic homogeneity across a species with a large range (staton & rice 1999). there is evidence for cryptic speciation in apionsoma misakianum (staton & rice 1999), and species delimitation may not be as clear as previously thought, especially for disjunct “populations” (maxmen et al. 2003). however, it is unusual to find two morphologically cryptic species that are not sister species (schulze et al. 2007). all polyphyletic species examined by schulze et al. (2007) were geographically widespread and inhabit hard substrates— mostly coral rubble—in shallow waters, and belong to genera that do not occur in polar areas. no endemism is shown by either antarctic or arctic sipuncula species (except for n. lilljeborgi , which might be endemic to cold deep waters). many of the most abundant species in both areas ( g. margaritacea, n. diaphanes and p. strombus) are cosmopolitan (saiz-salinas & pagolacarte 1999). the most numerous biogeographical group of sipuncula species found off svalbard are widespread in the atlantic ocean, occurring at a range of depths and in a wide variety of substrata. g. margaritacea and p. strombus have a very wide distribution in the atlantic ocean, but live at greater depths at lower latitudes (cutler 1994). in svalbard waters they were found only below 400 m. one species (g. elongata) is a tropical/boreal one, but in svalbard waters it seems to occur rarely. the genus nephasoma is especially richly represented in cold bathyal and abyssal waters of the northern atlantic and pacific (cutler 1994). n. abyssorum has repeatedly been reported from svalbard (fischer 1895, 1922, 1929) but was not found in this study. it is a common bathyal and abyssal species in the north-eastern atlantic and the arctic ocean. it is very likely that it is still present in the svalbard area but has been missed in our survey because of the scarcity of deep-sea samples. the same conclusion applies to n. eremita. this bipolar species has previously been reported from svalbard (théel 1905; fischer 1922, 1929; gulliksen et al. 1999) but did not occur in our samples (table 3). it is very likely that the poor knowledge regarding the sipuncula may lead to erroneous statements regarding the occurrence of sipunculans in arctic regions. that was probably the reason that g. vulgaris has not been reported from svalbard, although it is a widely distributed species in greenland, scandinavia (théel 1905; wesenberg-lund 1925, 1937a; cutler 1994) and in many arctic seas (sirenko 2001). m. kȩdra & g.v. murina the sipunculan fauna of svalbard polar research 26 (2007) 37 – 47 © 2007 the authors 43 acknowledgements we would like to express our deep thanks to the crew and staff of the rv oceania and the rv polarstern involved in the expeditions. we would like to thank akvaplan-niva, polar environmental center, n-9296, tromsø, norway for providing samples. many thanks to the naturalis national natural history museum, in leiden, the zoological museum of the university of copenhagen and the museum of natural history, in berlin, for providing us access to their collections. many thanks to the zoological museum of the university of copenhagen, for providing us with the opportunity to take pictures and for allowing us to use their scanning electron microscope. we would like to acknowledge the financial support of the european commission’s research infrastructure action via the synthesys project. references angel m.v. 1996: oceanic biodiversity: origins and maintenance. in g. albertelli et al. (eds.): atti del 11 congresso della associazione italiana di oceanologia e limnologia, sorrento, 26–28 ottobre 1994. (proceedings of the 11th congress of the italian association of oceanography and limnology, sorrento, 26–28 october 1994.) pp. 33–60. genova: aiol. beszczynska-möller a., wfslawski j.m., walczewski w. & zaj`czkowski m. 1997: estimation of glacial meltwater discharge into svalbard coastal waters. oceanologia 39, 289–298. bouchet p. & waren a. 1979: the abyssal molluscan fauna of the norwegian sea and its relation to other faunas. sarsia 64, 211–243. clarke a. & crame j.a. 1997: diversity, latitude and time: patterns in the shallow sea. in r.f.g. ormong et al. (eds): marine biodiversity. patterns and processes. pp. 122–147. cambridge: cambridge university press. clarke k.r. & warwick r.m. 2001: change in marine communities: an approach to statistical analysis and interpretation. 2nd edn. plymouth: plymouth marine laboratory. cutler e.b. 1968: a review of coral-inhabiting sipuncula. océanographie 3, 51–63. cutler e.b. 1994: the sipuncula. their systematics, biology, and evolution. new york: cornell university press. cutler e.b., cean h.k. & saiz-salinas j.i. 2001: sipuncula from antarctic waters. proceedings of the biological society of washington 114, 861–880. cutler e.b. & cutler n.j. 1986: a revision of the genus nephasoma (sipuncula: golfingiidae). proceedings of the biological society of washington, 99, 547–573. cutler e.b. & cutler n.j. 1987a: deep-water sipuncula from the eastern atlantic ocean. sarsia 72, 71–89. cutler e.b. & cutler n.j. 1987b: revision of the genus golfingia (sipuncula: golfingiidae). proceedings of the biological society of washington 100, 735–761. dayton p.k., mordidia b.j. & bacon f. 1994: polar marine communities. american zoology 34, 90–99. dunton k. 1992: arctic biogeography: the paradox of the marine benthic fauna and flora. trends in ecology and evolution 7, 183–189. fischer w. 1895: die gephyreen des naturhistorschen museums zu hamburg. (gephyreans of the natural history museum in hamburg.) abhaltungen aus dem gebiet der naturwissenschaften (hamburg) 13, 1–24. fischer w. 1914: weitere mitteilungen über die gephyreen des naturhistorischen (zoologischen) museums zu hamburg. (further reports on the gephyreans of the natural history [zoological] museum in hamburg.) jahrbuch der hamburgischen wissenschaftlichen anstalten 31, 1–28. fischer w. 1922: gephyreen der arktischen meere. (gephyreans of the arctic seas) wissenschaftliche meeresuntersuchungen abteilung helgoland 13, 229–246. fischer w. 1929: die sipunculiden, priapuliden und echiuren der arktis. (arctic sipuncula, priapulada and echiura). in f. römer & f. schaudinn (eds.): fauna arctica. vol. 5. pp. 451–490. jena: verlag von gustav fischer. gibbs p.e. 1975: gametogenesis and spawning in a hermaphroditic population of golfingia minuta (sipuncula). journal of the marine biological association of the united kingdom 55, 69– 82. gibbs p.e. 2001: sipunculans. key and notes for the identification of british species. synopses of the british fauna (new series) 12. dorchester: linnean society of london/estuarine and coastal sciences association. gray j.s. 2001: antarctic marine benthic biodiversity in a world-wide latitudinal context. polar biology 24, 633–641. gulliksen b., palerud r., brattegard t. & sneli j. 1999: distribution of marine benthic macro-organisms at svalbard (including bear island) and jan mayen. research report for dn 1999-4. trondheim: directorate for nature management. hylleberg j. 1970: fauna associated with the sipunculid phascolion strombi (montagu), especially the parasitic gastropod menestho diaphana (jeffryes). ophelia 7, 257–276. kohn a.j. 1975: predation on sipunculans. in m.e. rice & m. todoroviæ (eds): proceedings of the international symposium on the biology of the sipuncula and echiura, kotor. pp. 313–333. belgrade: nauèno delo press. loeng h. 1991. features of the physical oceanographic conditions of the barents sea. in e. sakshaug et al. (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, norway, 12–16 may 1990. polar research 10, 5–18. maxmen a.b., king b.f., cutler e.b. & giribet g. 2003. evolutionary relationships within the protostome phylum sipuncula; a molecular analysis of ribosomal genes and histone h3 sequence data. molecular phylogenetics and evolution 27, 489–503. murina g.v. 1975: the geographical distribution of marine worms of the phylum sipuncula of the world ocean. in m.e. rice & m. todorovic (eds.): proceedings of the international symposium on the biology of the sipuncula and echiura. vol. 1. pp. 9–18. belgrade: nauèno delo press. murina g.v. 1977: marine worms of the arctic and boreal waters of europe. (morskie chervi sipunkulidy arkticheskikh i borealnykh 44 polar research 26 (2007) 37 – 47 © 2007 the authors the sipunculan fauna of svalbard m. kędra & g.v. murina vod evrazii.) identification books of the ussr fauna 111. leningrad: akademii nauk sssr. murina g.v. 1984: ecology of sipuncula. marine ecology progress series 17, 1–7. murina g.v. & sørensen j. 2004: marine worms of the phylum sipuncula in faroese waters. fró~skaparrit 51, 280–291. ormond r.f.g., gage j.d. & angel m.v. 1997: marine biodiversity. patterns and processes. cambridge: cambridge university press. romero-wetzel m.b. 1987: sipunculans as inhabitants of very deep, narrow burrows in deep-sea sediments. marine biology 96, 87–91. saiz-salinas j.i. 1995: sipuncula of the southeastern weddell sea (antarctica). polar biology 15, 307–317. saiz-salinas j.i. & pagola-carte s. 1999: sipuncula of the magellan area compared with adjacent regions of antarctica. scientia marina 63, 227–232. saiz-salinas j.i. & villafranca urchegui l. 1990: sipuncula from the alboran sea and ibero-morroccan bay. journal of natural history 24, 1143–1177. scheltema r.s. 1975: the frequency of long-distance larval dispersal and rate of gene-flow between widely separated populations of sipunculans. in m.e. rice & m. todorovic (eds.): proceedings of the international symposium on the biology of the sipuncula and echiura. pp. 199–210. belgrade: nauèno delo press. scheltema r.s. & hall j.r. 1975: the dispersal of pelagosphaera larvae by ocean currents and the geographical distribution of sipunculans. in m.e. rice & m. todorovic (eds): proccedings of the international symposium on the biology of the sipuncula and echiura. pp. 103–115, belgrade: nauèno delo press. scheltema r.s. & rice m.e. 1990: passive dispersal of planktonic larvae and the biogeography of tropical sublittoral invertebrate species. in g. colombo et al. (eds.): marine eutrophication and population dynamics. pp. 195–202. fredenborg: olsen and olsen. schulze a., cutler e.b. & giribet g. 2007. phylogeny of sipunculan worms: a combined analysis of four gene regions and morphology. molecular phylogenetics and evolution 42, 171– 192. sirenko b.i. 2001. list of species of free-living invertebrates of eurasian arctic seas and adjacent deep waters. explorations of the fauna of the seas 51, st petersburg: zoological institute, russian academy of sciences. staton j. & rice m.e. 1999. genetic differentiation despite teleplanic larval dispersal: allozyme variation in sipunculans of the apionsoma misakianum species complex. bulletin of marine science 65, 467–480. stearley r.f. & ekdale a.a. 1989: modern marine bioerosion by marcoinvertebrates from the northern gulf of california. palaois 4, 453–467. stevens g.c. 1989: the latitudinal gradient in geographical range: how so many species coexist in the tropics. the american naturalist 33, 337–351. svendsen h., beszczynska-möller a., hagen j.o., lefauconnier b., tverberg v., gerland s., orbæk j.b., bischof k., papucci c., zaj`czkowski m., azzolini r., bruland o., wiencke c., winther j.g. & dallmann w. 2002: the physical environment of kongsfjorden–krossfjorden, an arctic fjord system in svalbard. polar research 21, 133–166. théel h. 1905: northern and arctic invertebrates in the collection of the swedish state museum. i. sipunculids. kungliga svenska vetenskapsakademiens handlingar 3, 1–30. wesenberg-lund e. 1925: gephyreer. conspectus faunae groenlandicae. (gephyreans. conspectus of greenland fauna.) meddelelser om grønland 23, 81–91. wesenberg-lund e. 1930: priapulida and sipunculidae. danish ingolf expedition 4, 1–44. wesenberg-lund e. 1933: the collections of gephyreans in the royal museum of natural history of belgium. bulletin de l’institut royal des sciences naturelles de belgique 9, 1–15. wesenberg-lund e. 1934: gephyrans and annelids. the scoresby sound committee’s second east greenland expedition in 1932 to king christian 9th’s land. meddelelser om grønland 104, 1–38. wesenberg-lund e. 1937a: the zoology of east greenland: gephyreans. meddelelser om grønland 121, 1–25. wesenberg-lund e. 1937b: gephyrea. the zoology of iceland 2, 1–17. wesenberg-lund e. 1938: the godthaab expedition 1928. gephyrea. meddelelser om grønland 79, 1–29. wesenberg-lund e. 1955: sipunculidae. reports of the swedish deep-sea expedition. zoology 2, 199–201. wfslawski j.m., zajaczkowski m., kwa niewski s., jezierski j. & moskal w. 1988: seasonality in an arctic fjord ecosystem: hornsund, spitsbergen. polar research 6, 185–189. wlodarska-kowalczuk m., kendall m.a., wfslawski j.m., klages m. & soltwedel t. 2004: depth gradients of benthic standing stock and diversity on the continental margin at a high-latitude ice-free site (off spitsbergen, 79°n). deep-sea research part i 51, 1903–1914. wlodarska-kowalczuk m. & pearson t.h. 2004: soft-bottom macrobenthic faunal associations and factors affecting species distribution in an arctic glacial fjord (kongsfjord, spitsbergen). polar biology 27, 155–167. s¢ m. kȩdra & g.v. murina the sipunculan fauna of svalbard polar research 26 (2007) 37 – 47 © 2007 the authors 45 appendix. simplified identification key to families, genera and species of sipuncula from the arctic region (svalbard species are indicated in boldface). key to families of class sipunculidea: 1. longitudinal muscles of body wall gathered into either separate or anastomosing bands (20–24) sipunculus norvegicus — longitudinal muscles of body wall in uniform continuous layer 2 2. a single nephridium present phascolionidae — two nephridia present golfingiidae key to golfingiidae: 1. four introvert retractor muscles present golfingia — two introvert retractor muscles present nephasoma key to golfingia species 1. introvert hooks in rings golfingia elongata — introvert hooks scattered, if present 2 2. hooks present and scattered; central part of the trunk smooth, often transparent, both trunk ends dark and heavy papillated golfingia vulgaris (fig. 3) — hooks on introvert absent; small papillae present on the trunk golfingia margaritacea (fig. 4) key to nephasoma species 1. hooks absent nephasoma eremita (fig. 5) — hooks scattered 2 — hooks arranged in rings or otherwise 4 2. scattered small hooks; body transparent to translucent, usually <10 mm long 3 — scattered small triangular hooks; body opaque, up to 40 mm long. from bathyal depths nephasoma lilljeborgi (fig. 6) 3. body skin smoothly glossy and transparent; introvert with a few short tentacular lobes nephasoma diaphanes diaphanes (fig. 7) — body skin translucent to opaque, with irregular longitudinal epidermal ridges on the introvert base and the anterior part of the trunk nephasoma diaphanes corrugatum 4. large hooks (>50 µm) in a spiral arrangement, like a barber’s pole nephasoma abyssorum key to phascolionidae: 1. epidermal holdfast papillae present phascolion 2. epidermal holdfast papillae absent onchnesoma key to phascolion species: 1. ventral retractor much thinner then dorsal; holdfast papillae v-shaped with dark, hardened border p. strombus (fig. 8) 2. ventral and dorsal retractors have equal width; large holdfast papillae without hardened borders p. turberculosum key to onchnesoma species: 1. trunk covered with prominent backward directed protrusions; eight tentacles o. squamatum 2. trunk flat without spherical protrusions or scales; tentacles absent o. steenstrupii 46 polar research 26 (2007) 37 – 47 © 2007 the authors the sipunculan fauna of svalbard m. kędra & g.v. murina figure 4 the interior organs of golfingia margaritacea showing four introvert retractor muscles. figure 5 golfingia eremita.figure 6 nephasoma lilljeborgi. figure 3 scanning electron micrographs of the small hooks of golfingia vulgaris. (scanning electron microscope pictures were taken at the zoological museum of the university of copenhagen.) m. kȩdra & g.v. murina the sipunculan fauna of svalbard polar research 26 (2007) 37 – 47 © 2007 the authors 47 figure 8 phascolion strombus. scanning electron micrographs of the holdfast papillae of p. strombus. figure 7 nephasoma diaphanes diaphanes in foraminiferal tests. the polar bear ursus maritimus feeding in a seabird colony in frans josef land lech stempniewicz stempniewicz, l. 1993: the polar bear ursus maririmus feeding in a seabird colony in frans josef land. polar research i z ( 1 ) . 33-36. during the second half of august 1992 polar bears were observed feeding intensively in the little auk aiie alle colony on rubini rock, hooker island, frans josef land. they dug out nests eating eggs, chicks and adult birds. their activity results in both worsening the breeding conditions and decreasing the breeding success of the little auks. the polar bear has not earlier been known as a little auk predator. l . slempniewicz, department of vertebrate ecology & zoology, universiq of g h h k , legiondw 9, 80 441 gdatisk, poland. introduction the polar bear vrsus maritimus is an oppor tunistic omnivore. it most often hunts for seals, mainly the ringed seal phoca hispida and bearded seal erignathus barbatus as well as the harp seal pagophilus groenlandicus and hooded seal cys tophora crktata. sporadically it attacks walruses (odobaenus rosmarus), belugas (delphinapterus leucas) and narwhals (monodon monoceros). polar bears also occasionally kill large terrestrial vertebrates, such as muskoxen (ouibos mosch atus), reindeer (rangifer tarandus) and even dom estic animals and humans (larsen 1978; smith 1980; 1985; gjertz & persen 1987; uspensky 1989). moreover, polar bears are both scavengers, feeding on carrion and offal, and cannibals (especially adult males), attacking young, weak and ill specimens (taylor et al. 1985). their diet also consists of plants, both of marine (e.g. lami naria spp.) and terrestrial origin (e.g. grasses, mosses, lichens, berries, salk spp.). food com position shows large seasonal and geographical differentiation due to local and temporal food availability. some individuals can develop special ised foraging techniques (larsen 1978; uspensky 1989). in some regions birds constitute a supplemen tary prey for polar bears during the summer. ducks (somateria spp., clangula hyemalis) and geese (branta spp., chen spp.) nesting in high density on flat islets and coastal tundra are rela tively easy prey. the polar bears eat eggs, chicks and incubating parents as well as flightless, moult ing individuals. birds are not even safe on the water where polar bears swim quietly toward them, dive and catch them from underneath (rus sel 1975; larsen 1978). polar bears often visit arctic islands which are populated with large seabird colonies. they pen etrate the cliff foot searching for dead birds and for eggs and nestlings that have fallen from the nests. they also try to plunder lower situated nests of guillemots uria spp. and kittiwakes rissa spp. polar bears can dig out burrow-nesting sea birds (e.g. puffins fratercufa spp.) and lemmings (lemmus spp., dicrostonyx spp.) (larsen 1978; brown 1988; uspensky 1989). large gull species and particularly the glaucous gull larus hyperboreus and arctic fox alopex lagopus belong to the most important little auk alle alle predators. the arctic skua stercorarius parasiticus preys upon them sporadically (stempniewicz 1981, 1983). no information was found in the available literature indicating that the polar bear is a little auk predator. study area the study took place in the little auk colony on rubini rock, hooker island, frans josef land (82'18'n, 52'37'e). my base was a hut located at 34 l . stempniewicz fig. 1. study area: a. contour map; b. sketch of the southern part of the rubini rock. the arrow on part a indicates a general direction of the polar bears in passing the study area. the foot of rubini rock, several hundred metres from the colony (fig. 1). the area apparently lies on the route of polar bear passage. the polar bears approached rubini rock from the southwest and left the area to the northeast, keep ing more or less close to the coast. during the first 10 days of the study, 22 polar bears were observed in near vicinity. the large seabird breed ing aggregation could be responsible, or at least partially responsible, for the presence of the polar bears. situated on a steep rocky cliff which drops directly to the sea, most of the colony is com pletely inaccessible for terrestrial predators, including man. several thousands of brunnich's guillemots uria lomuia, kittiwakes rksa tridactyla and little auks, as well as some hundreds of ful mars fulmarus glacialis and black guillemots cepphus grylle, and a few glaucous gulls larus hyperboreus breed there. only from the southern side is rubini rock partly accessible. on the side of the cliff there is a talus slope inclined to about 45" and covered with rich vegetation (mainly alo pecurus alpinus, poa arctica, ranunculus sul phureus and cochlearia groenlandica). two little auk subcolonies are situated here in the rock debris (fig. 1). large numbers of little auks and some black guillemots and fulmars breed on the steep wall above the talus slope. observations in the period 15 august-5 september, polar bears were observed feeding on the southern (access ible) side of rubini rock. they penetrated both the foot of the cliff and the little auk subcolonies on the slope. at the base of the cliff they searched for dead birds and attempted to reach the lower little auk nests by standing on their hind limbs and pawing the rock fragments to uncover the nesting crevices. only a small number of nests were situated low enough to fall within the range of polar bear paws, and most of the boulders were too large to overturn. moreover, adult little auks could take flight and the chicks could squeeze into another crevice. the polar bears spent much time here looking for food, resting and sleeping. i found several shallow holes in the ground where the polar bears had denned. these were lined with hair and the vegetation had been removed. excrements as well as extensively grazed grass were usually observed near the dens. polar bears feeding in the little auk subcolonies the polar bear ursus maritimus feeding in a seabird colony 35 on the talus slope used a different method. approaching as a rule from below, a bear would choose a place with high nest density and begin overturning the boulders which covered the nests. some of these often weighed several hundred kilos. having uncovered a nest, the bear would then eat the eggs, chicks and adult birds. the chicks and adults which moved deeper into the rock debris were caught when the bear pawed into the next layer of rock debris. finished with one area of the colony, the predator would climb several metres higher and begin again to dig in the rock debris. this behaviour was repeated until the bear reached the upper edge of the colony. during its search for food, the bear would rest for short periods, lying nearby on the grass. consequently, the feeding bear left behind it a trail of craters in the little auk colony. these craters measured from 0.5 to 0.7 m deep and from 0.7 to 1.5 m in diameter, depending on boulder size and nest density. polar bears apparently visit the colony in suc cessive years and during different stages of the little auk breeding period. the presence of fresh and old holes on the colony surface give evidence of this. fresh craters are green because algae covers the boulders from the deeper layers of the rock debris. old craters, like the rest of the colony surface, are free of vegetation because of the large amounts of little auk excreta deposited there. remnants of egg shells, blood traces and nestling excrements usually could be found within the craters. as chicks defecate at one corner of the nest, the presence of such a depot makes it poss ible to consider the nest as being occupied (stempniewicz 1990). bear excrements however, numerous on the talus slope, consisted almost exclusively of whole, undigested wings of adult little auks. though nestlings constitute also a considerable part of polar bear prey in the little auk colony, their remnants are difficult to recog nize in the bear faeces. most probably, this is because of a higher degree of assimilation of their tissues by bear alimentary tract. polar bears could catch adult birds staying in the nest during dif ferent stages of the little auk breeding period due to egg incubation, chick brooding and feeding. discussion most of the little auk population nests on rocky cliffs in frans josef land. this is a result of severe climatic conditions, i.e. low temperatures and long lasting ice and snow cover laying (gorbunov 1932; demme 1934). compared t o talus slopes, the steep rocky walls are free of snow and ice earlier and for a longer time during the summer. strong predatory pressure of the polar bears can also contribute t o little auk breeding in such an inaccessible habitat. only those little auks that are unable t o take over a limited number of such safe nesting places will breed in talus (stempnie wicz 1981, in prep; birkhead & h a m s 1985). as a result of polar bear activity in the little auk talus colony the talus surface becomes unstable. the movable boulders create an additional danger of crushing the little auk broods. snow cover remains for a long time in the craters dug out by the polar bears, making them humid. as the thin layer of rock debris does not provide enough insulation from the perma frost, these places are no longer attractive t o the little auks for breeding. no active nests were found in the old craters (28 craters examined) compared to mean nest density in the whole talus subcolony amounting to 0.25/m2. the highest density observed did not exceed 2 nests per 1 mz. polar bears choose rather central parts of the little auk colony which offer high nest density and ensure more efficient feeding. to dig a crater 0.6 m deep and 1 m in diameter in the rock debris, a bear must overturn boulders weighing several hundred kilos. at best it will find and plunder not more than two nests, i.e. 2 adult and 2 nestling birds weighing altogether about 0.5 kg. the search for food often yields less results because the bear may penetrate colony parts with lower nest density, meet boulders too large to move, or lose the prey which manages to escape. to cover its daily energy needs, estimated t o be 8 kg of seal meat and blubber (uspensky 1989), a bear would have to consume at least 32 adult and nestling little auks and dig 16 craters overturning several tonnes of rock debris. for these reasons the efficiency of polar bear feeding in the little auk colony, i.e. a relation of energy losses t o gains, doesn't seem high. it is possible that this feeding method is used only by some specialised and experienced individuals which are able t o detect dense patches of active nests covered with rock debris easy t o remove, thus improving their hunt ing efficiency. starving, inexperienced individuals q a y try t o follow this food searching pattern especially when other sources of food are not available. 36 l . stempniewicz for the reasons mentioned above, peripheral parts of the colony are less endangered by the predators, in contrast to the general rules of pred atory pressure exerted on colonial animals (per rim & birkhead 1983). the mean little auk nest density in the hornsund area (in a very similar habitat, but not visited by polar bears) amounts to 0.75/1 m2 (stempniewicz 1981). this is 3 times higher than that observed on rubini rock at the end of august. a large number of fresh (this year) cra ters observed in the central (most abundant) part of the rubini rock colony proves that nest density must have been considerably (about 2 times) higher at the beginning of the breeding season. polar bear predatory pressure can be significant for the little auk breeding success, especially in regions where polar bears are numerous during the spring and summer and little auk colonies are located close to the coastal line in the rock debris in easily accessible locations such as rubini rock. acknowledgements. data presented in this paper were col lected during the international expedition to frans josef land (rus-nor-pol '92). financial support was received from the university of gdadsk (grant nr. bw/1140-5-00872). my friend marcin wcstawski provided much appreciated help in the field. an anonymous referee gave valuable suggestions for improving the manuscript. references brown, r. g. 9.1988: seabirds and the arctic marine environ ments. 4. 131-150 in rey l. (ed.): marine living systems of the far north. proc. 6th conf. of the cornirk arctique international, unio. of almka, fairbanks, 13-15 may 1985. e. j. brill, leiden. birkhead, t. r. & hams, m. p. 1985: ecological adaptations for breeding in the atlantic alcidae. pp. 205-231 in nettleship d. n. & birkhead t. r. (eds.): the atlantic alcidae. academic press, london-toronto. 574 pp. demme, n. p. 1934: birds'bazaar on the rubini rock (hooker island, f r a u josef land). trudy arkr. inst. 11, 55-86 (in russian). gjertz, 1. & persen, e. 1987: confrontations between humans and polar bears in svalbard. polar res. 5 , 253-256. gorbunov, g. p. 1932: birds of f r a u josef land. trudy arkt. inst. 4 , 1-234 (in russian). larsen, t. 1978: the world of polar bear. hamlyn, london toronto. 96 pp. pemns. c. m. & birkhead, t. r. 1983: avian ecol. blackie, chapman & hall, new york. 221 pp. russel, r. h. 1975: the food habits of polar bears of james bay and south-west hudson bay in summer and autumn. arctic 28. 117-129. smith, t. g. 1980: polar bear predation of ringed and bearded seals in the land-fast sea ice habitat. can. 1. 2001. 58,2201 2209. smith, t. g. 1985: polar bears, onus muritimus, as predators of belugas, delphinapterus leucas. canadian field nat. 99, stempniewin, l. 1981: breeding biology of the little auk, plautus alle, in the hornsund region, spitsbergen. acta orni stempniewicz, l. 1983: hunting methods of the glaucous gull and escape manouvers of its prey, the dovekie. j . field ornirhol. 54, 328-331. stempniewicz, l. 1990: biomass of dovekie excreta in the vicinity of a breeding colony. colonial waterbirds 13,6246. taylor. m. k., larsen, t. & schweinsburg, r. 1985: obser vations of intraspecific aggression and cannabilism in polar bears. arctic 38, 303-309. uspensky, s. m. 1989. polar bear. agropromizdat., moskva, 190 pp. (in russian). 71-75. thol. 18, 141-165. mallorybirds.indd 399mallory & gilchrist 2003: polar research 22(2), 399–403 our knowledge of the distribution and abundance of marine birds in the canadian arctic remains patchy and incomplete. many of the early expeditions to the arctic recorded the distribution of some birds, and more recent extensive surveys or intensive research in some regions have fi lled in many gaps in our distribution maps (e.g. nettleship 1974; mclaren 1982). in some cases, information has come from geologists who have found colonies where biologists had not visited (e.g. frisch & morgan 1979). collectively, this information has helped identify most of the major seabird colonies in the canadian arctic (brown et al. 1975). however, distributions of birds, especially those species that breed in small, dispersed colonies, remain largely unknown. in 2002 and 2003, we surveyed some of the smaller islands in penny strait and queens channel of the central canadian high arctic, nunavut. this marine area is relatively shallow with strong tidal currents, and supports recurrent areas of open water (polynyas), making it particularly important for many types of arctic marine wildlife (stirling 1997). despite this, only a few islands in this area have been surveyed for birds, mostly to the east of the area we covered (nettleship 1974). in general, the avifauna of this region was poorly known and had not been surveyed in over 20 years, but it was previously an important breeding area for the rare ivory gull (pagophila eburnea; haney & macdonald 1995) and ross’s gull (rhodostethia rosea; macdonald 1978). our goals were to: a) check on the breeding status of ross’s and ivory gulls at these important colonies; b) search for new colonies of these species; and c) document the occurrence and breeding site characteristics of other marine bird colonies in the region. methods surveys were conducted on 16 july 2002 and 10 july 2003 using a bell 206 l4 helicopter. during marine birds breeding in penny strait and queens channel, nunavut, canada mark l. mallory & h. grant gilchrist surveys of breeding birds on small islands in penny strait and queens channel, nunavut territory, canada, were conducted in july 2002 and 2003. approximately 3600 marine birds were observed, with the most common species being arctic terns (sterna paradisaea, n = 2400) and common eiders (somateria mollissima borealis, n = 620). we observed no ross’s gulls (rhodostethia rosea) in either year, and we found ivory gulls (pagophila eburnea) only in 2003, even though these species commonly bred here in the 1970s. this previously unsurveyed region supports numerous breeding marine birds, but reproductive success on these small islands may be dependent on annual ice conditions and consequent movements of arctic foxes (alopex lagopus). m. l. mallory, canadian wildlife service, box 1714, iqaluit, nu, x0a 0h0, canada, mark.mallory@ec.gc.ca; h. g. gilchrist, national wildlife research centre, carleton university, raven road, ottawa, on, k1a 0h3, canada. research note 400 marine birds breeding in penny strait and queens channel, nunavut the surveys in both years, skies were clear (only 10 % cloud cover) and there were light northerly wind conditions (approximately 15 km/h). in 2002, 100 % ice cover persisted to the north and west (parker strait, young inlet), but penny strait and most of queens channel had < 10 % ice cover; the choppy water surface suggested strong tides or currents around most small islands. in 2003, ice cover was more extensive, with many islands connected to nearby large islands by ice bridges. we surveyed small islands in 2002 in the strait between 75° 48' n and 76° 41' n, and bounded in longitude by 95° 39' w and 101° 57' w. we landed on most islands and conducted surveys by foot, but in a few cases islands were very small and barren, and we surveyed while hovering at approximately 10 m altitude. two biologists divided the islands into sections and counted nests or numbers of birds in each portion, and then tallied totals at the end of each survey. in 2003, we resurveyed seymour island, the cheyne islands and the small island east of crozier island. results we visited 16 islands in penny strait and queens channel (fig. 1) and to the north of bathurst island in 2002. we found no ross’ gulls and no ivory gulls on any of the islands during the surveys. moreover, we did not see any evidence that they attempted to breed in 2002; in fact, we could not see any signs of recent or old nests. no individuals of either species were observed anywhere in the survey region. in 2003 we also failed to fi nd any ross’ gulls, but 200 ivory gulls (including some breeders) were observed on seymour island, as well as 17 arctic terns (sterna paradisaea), 4 eastern high arctic brant (branta bernicla hrota) and 2 king eiders (somateria spectabilis). in addition to our target species, we recorded numerous new observations of marine birds in the area, as well as physical characteristics of the islands with which they were associated (table 1). collectively we found 12 avian species, including arctic tern, common eider (somateria mollissima fig. 1. map of islands surveyed in july 2002 in penny strait and queen’s channel, nunavut. numbers correspond to table 1. 401mallory & gilchrist 2003: polar research 22(2), 399–403 borealis), red phalarope (phalaropus fulicaria), red-throated loon (gavia stellata), glaucous gull (larus hyperboreus), long-tailed duck (clangula hyemalis), parasitic jaeger (stercorarius parasiticus), common raven (corvus corax), black-legged kittiwake (rissa tridactyla), peregrine falcon (falco peregrinus), sabine’s gull (xema sabini) and eastern high arctic brant. a few island observations merit particular description. first, south cheyne island was notable because of its brilliant green moss associated with an eider breeding colony. in 2002 we found 149 eider nest cups, of which 63 were unoccupied, two had failed and 84 were active and contained eggs. clutch sizes ranged from one to fi ve eggs, with a mean clutch size of 3.4 ± 0.9 sd (n = 84). in 2003, only 36 active nests were observed, with a mean clutch size of 2.5 ± 1.0 sd (n = 36), and 36 failed nests were observed. interestingly, middle cheyne island, about 2 km north, was also covered with moss and appeared to have supported a large bird colony, but held few birds in 2002 or 2003 and did not appear to have been active for some time. we found 30 old eider nest cups at this site. the unnamed island east of crozier island was also covered in moss and herbaceous growth. skeletons of seals and bears suggested that inuit had used this as a campsite in the past. the island supported the highest diversity and abundance of breeding birds among all islands surveyed, with many birds associated with the scattered freshwater ponds. arctic terns had breeding colonies at both ends of the island, with a small sabine’s gull colony associated with the south-western table 1. locations, characteristics and numbers of individuals of species observed on islands in penny strait and queens channel, nunavut, july 2002. the “ice” column indicates the presence or absence of sea ice connecting the island to the nearest shore. species codes are: arctic tern (at), common eider (ce), red phalarope (rp), glaucous gull (gg), sabine’s gull (sg), redthroated loon (rtl), long-tailed duck (ltd), parasitic jaeger (pj), arctic fox (fox), common raven (cr), peregrine falcon (pf) and high arctic brant (hab). species observed no. name lat (°n) long (°w) distance to shore (km) size (km) vegetation > 30 % elevation (m) ponds ice at ce rp gg sg other 1 reid 76.01 97.16 10 0.15 × 0.05 no 3 0 yes 100 a 14 70 2 south cheyne 76.29 97.52 5 0.3 × 0.1 yes 3 1 no 600 a 164 6 a rtl (2), ltd (10) 3 middle cheyne 76.31 97.52 5 1.5 × 0.1 yes 3 9 no 212 a 11 rtl (2), pj (2) 4 north cheyne 76.34 97.52 7 0.75 × 0.1 no 3 1 no 16 a 2 a 50 2 a fox 5 seymour 76.80 101.27 11 2.5 × 1 no 9 0 yes 6 unnamed 76.60 101.83 1.5 3.5 × 1 no 10 0 yes 7 unnamed 76.60 101.94 5 2 × 0.5 no 10 0 yes 8 harwood 76.68 99.74 2 2 × 1 no > 10 0 no 2 9 hooker 1 76.63 98.11 5 0.75 × 0.5 no > 10 2 no 11 a cr (1) 10 hooker 2 76.62 98.13 3.5 2 × 0.3 no 0 no 100 a 13 a 2 ltd (3) 11 irving 76.55 97.72 2 0.5 × 0.5 no 5 1 no 140 a 12 a 24 a 12 hyde parker 76.47 97.17 13 6 × 3 no 1 no 8 a 34 a 13 assistance 76.36 96.24 10 0.5 × 0.1 no 3 0 no 240 a 4 a 14 des voeux 76.18 96.94 12 2.5 × 1 no 10 0 no 2 a pf 15 unnamed 75.82 96.31 16 3 × 1 yes 10 > 5 no 900 a 375 a 100 30 a hab (6), rtl, cr (3) 16 crozier b 75.80 96.44 23 10 × 4 yes 15 no fox, hab (60) 17 young inlet c 76.60 99.25 yes 60 hab (120) a breeding was confi rmed, though not all birds were necessarily breeders. b this island was partially surveyed. c composite of birds counted along beaches of this inlet. 402 marine birds breeding in penny strait and queens channel, nunavut tern colony. in 2003, similar numbers of gulls and terns were observed on the island, but only 91 eiders were found. finally, in 2002 we saw two arctic foxes (alopex lagopus) trapped on islands for the summer, and three islands with no birds were still connected to the mainland by ice. collectively, surveys of small islands in this region yielded counts of approximately 2400 arctic tern, 620 common eider, 230 red phalarope, 200 high arctic brant, 60 sabine’s gull and 40 glaucous gull in 2002. the partial resurvey in 2003 yielded observations of ivory gulls at seymour island, but lower numbers of eiders on other islands. discussion approximately 3600 marine birds were observed on or around 16 small islands in penny strait and queens channel. the extent to which we can extrapolate these numbers is unknown because our sample was not random. larger islands may be more suitable for year-round habitation by some key predators on marine birds, notably arctic fox, so the small islands we censused may in fact be the most suitable habitat in this region for these species, particularly for terns and eiders. islands that remained locked in ice in july tended to support few birds, perhaps because they could be reached by foxes when the birds attempted to breed. this hypothesis was supported by the lower number of eiders observed on the resurveyed islands in 2003, a year when considerably more ice connected islands in penny strait. our survey revealed disturbing information on rare species previously known to nest in this region. the ivory gull colony at seymour island, a former research site (haney & macdonald 1995), was not occupied in 2002, and in 2003 supported only about half the number of gulls that previously bred there in the 1970s. the decline of birds from seymour island is consistent with other reports of ivory gull declines across the canadian arctic based on inuit ecological knowledge (mallory et al. 2003), ship-based surveys (a. j. fontaine, unpubl. data) and other colony surveys (gilchrist & mallory, unpubl. data). the lack of any birds on seymour island in 2002, but the presence of four breeding species in 2003 suggests that a predator may have destroyed all avian nests in 2002. interestingly, in 2002 we saw no ivory gulls anywhere in this region, so if they failed to breed then they apparently moved out of this area. presumably mammalian predators had not reached the island in 2003, even through regional ice cover was heavier than in 2002. despite the variation in breeding numbers, the salient point is that fewer ivory gulls appear to inhabit seymour island now than in the past. we failed to observe any ross’ gulls in this region in either year, nor any evidence of recent nesting on the cheyne islands. macdonald (1978) found up to six pairs of this species breeding on these small islands in 1976 and 1978, making this the largest known colony of ross’ gulls in canada. birds were also observed in the area in 1974, but none were found nesting in 1977 or 1979. if this species skipped or failed breeding in both 2002 and 2003, it is odd that breeding conditions (e.g. weather, predation) were apparently suitable in both years for nests of other gulls, terns and eiders on these islands. it may be that ross’ gulls no longer nest on the cheyne islands. another surprising fi nd was the large, verdant middle cheyne island that supported virtually no breeding birds. the presence of so much vegetation on this site suggested considerable nutrient input, and hence that the island once hosted a large bird colony, probably eiders (since there were freshwater ponds on the site). why any substantial bird colony was absent during our recent surveys is unclear, given that eiders and terns were nesting by the hundreds at the wellestablished colony on south cheyne island, 2 km away. there were only about half as many eiders observed at the two main colonies in this region in 2003 compared to 2002, perhaps in response to increased sea ice cover and corresponding enhanced ability of mammalian predators to move among islands. nonetheless, the observation of at least 600 common eiders nesting in the region is new and important information for monitoring this species in the eastern canadian arctic (goudie et al. 2000). although much of the survey information suggested declines or absence of some species, we did record many new observations of breeding marine birds in this region. in particular, our surveys confi rmed the suspected breeding of sabine’s gulls in this area (blomqvist & elander 1981), and also supported the observation that this species often nests in association with arctic terns (day et al. 2001). the abundant tern colonies were scattered across the low, gravel islands of penny strait, and the preponderance of these 403mallory & gilchrist 2003: polar research 22(2), 399–403 types of islands suggests that this marine region is an important breeding area for this species. our surveys provide a baseline for future comparison of populations in this region, and in particular the roles that island characteristics, annual ice conditions and movements of arctic foxes play on breeding site selection and reproductive success of gulls, terns and eiders. moreover, the unnamed island east of crozier island appears very suitable for future studies of species ecology and interactions between sabine’s gulls and arctic terns. acknowledgements.—thanks to geoff goodyear and universal helicopters for superb fl ights, and to knud falk and an anonymous referee for thoughtful reviews of the manuscript. we gratefully acknowledge the fi nancial and logistic support of the polar continental shelf project (natural resources canada), the nunavut wildlife research trust (nunavut wildlife management board) and the canadian wildlife service (environment canada). references blomqvist, s. & elander, m. 1981: sabine’s gull (xema sabini), ross’s gull (rhodostethia rosea) and ivory gull (pagophila eburnea) gulls in the arctic: a review. arctic 34, 122–132. brown, r. g. b., nettleship, d. n., germain, p., tull, c. e. & davis, t. 1975: atlas of eastern canadian seabirds. ottawa: canadian wildlife service. day, r., stenhouse, i. & gilchrist, h. g. 2001: sabine’s gull, xema sabini. the birds of north america (a. poole & f. gill eds.) 593. philadelphia: the birds of north america, inc. frisch, t. & morgan, w. c. 1979: ivory gull colonies in southeastern ellesmere island, arctic canada. can. field-nat. 93, 173–174. goudie, r. i., robertson, g. j. & reed, a. 2000: common eider, somteria mollissima. the birds of north america (a. poole & f. gill eds.) 546. philadelphia: the birds of north america, inc. haney, j. c. & macdonald, s. d. 1995: ivory gull, pagophila eburnea. the birds of north america (a. poole & f. gill eds.) 175. philadelphia: the birds of north america, inc. macdonald, s. d. 1978: first breeding record of ross’s gull in canada. proceedings of the colonial waterbird group 1978, 16. mallory, m. l., gilchrist, h. g., akearok, j. a. & fontaine, a. j. 2003: local ecological knowledge of ivory gull declines in arctic canada. arctic 56, in press. mclaren, p. l. 1982: spring migration and habitat use by seabirds in eastern lancaster sound and western baffi n bay. arctic 35, 88–111. nettleship, d. n. 1974: seabird colonies and distribution around devon island and vicinity. arctic 27, 95–103. stirling, i. 1997: the importance of polynyas, ice edges, and leads to marine mammals and birds. j. mar. syst. 10, 9–21. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /all /binding /left /calgrayprofile (dot gain 20%) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages true /colorimagedownsampletype /bicubic /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages true /grayimagedownsampletype /bicubic /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /fra <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> /enu (use these settings to create pdf documents with higher image resolution for improved printing quality. the pdf documents can be opened with acrobat and reader 5.0 and later.) /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308000200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e30593002537052376642306e753b8cea3092670059279650306b4fdd306430533068304c3067304d307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e30593002> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <feff004e00e4006900640065006e002000610073006500740075007300740065006e0020006100760075006c006c006100200076006f0069006400610061006e0020006c0075006f006400610020005000440046002d0061007300690061006b00690072006a006f006a0061002c0020006a006f006900640065006e002000740075006c006f0073007400750073006c00610061007400750020006f006e0020006b006f0072006b006500610020006a00610020006b007500760061006e0020007400610072006b006b007500750073002000730075007500720069002e0020005000440046002d0061007300690061006b00690072006a0061007400200076006f0069006400610061006e0020006100760061007400610020004100630072006f006200610074002d0020006a00610020004100630072006f006200610074002000520065006100640065007200200035002e00300020002d006f0068006a0065006c006d0061006c006c0061002000740061006900200075007500640065006d006d0061006c006c0061002000760065007200730069006f006c006c0061002e> /ita <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> /nor <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> /sve <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> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice robertson.indd 85robertson et al. 2001: polar research 20(1), 85–94 clutch, egg and body size variation among common eiders breeding in hudson bay, canada gregory j. robertson, austin reed & h. grant gilchrist the hudson bay common eider (somateria molissima sedentaria) is a unique subspecies of eider that remains within the confines of hudson bay throughout the year. we compared clutch, egg and body size variation among populations of common eiders breeding in eastern and western hudson bay. clutch size did not differ substantially among these populations. all eiders in hudson bay laid larger clutches than other subspecies in eastern north america. as hudson bay common eiders do not undergo extensive migrations, they may have more energy reserves available to them for egg production. eiders nesting in eastern hudson bay laid larger eggs than eiders nesting in western hudson bay. further, eiders in eastern hudson bay tended to be structurally larger, but had smaller bill processes. these differences may have a genetic basis. smaller egg size and body size may arise in western hudson bay from mixing with the smaller borealis subspecies nesting to the north. further work to resolve genetic affinities, determine levels of male and female dispersal, and examine variation in reproductive ecology are needed to resolve the sources of these differences. g. j. robertson, canadian wildlife service, 6 bruce street, mount pearl, newfoundland a1n 4t3, canada; a. reed, canadian wildlife service, 1141 route de l’église, ste-foy, québec g1v 4h5, canada; h. g. gilchrist, canadian wildlife service, suite 301, 5204 50th avenue, yellowknife, northwest territories x1a 1e2, canada. many species of birds show variation in morphological, behavioural and/or life history characters across their ranges. this variation can be clinal or discrete (rockwell & barrowclough 1987), and populations showing discrete differences may be designated as subspecies. alternatively, differences among populations may reflect differential phenotypic expression of traits in different environments. documenting variation among populations has important implications for evolutionary, systematic and biogeographical studies and for conservation efforts (avise & hamrick 1996). among waterfowl, ducks tend to show less intraspecific variation than geese in morphological and life history traits across their range. common eiders (somateria mollissima) are one of the most variable ducks and have seven distinct subspecies (palmer 1976; cramp & simmons 1977), which show morphological and life history trait differences. in this regard common eiders are similar to geese, which also tend to show considerable variation among populations and subspecies (dunn & macinnes 1987). clutch, egg and body size are all important life history/morphological traits. in particular, clutch size is an important component of reproductive output (winkler & walters 1983). variation in clutch size among populations may reflect different selective regimes, environmental conditions, and/or age structure (rohwer 1992). factors governing egg size variation are less clear (williams 1994). variation in egg size among populations 86 clutch, egg and body size variation among common eiders may result from selection for different sized eggs in different environments, from genetic drift, different environmental conditions, and/or differences in age structure. body size is heritable (boag & van noordwijk 1987; van noordwijk et al. 1988), although environmental conditions, specifically food availability during growth, can influence final adult body size (cooch et al. 1991; leafloor et al. 1998). therefore, differences in body size among populations may reflect different selective pressures, population isolation and genetic drift, or different environmental conditions. in this study we investigated patterns of clutch, egg and body size variation among populations of the hudson bay subspecies of the common eider (somateria mollissima sedentaria). as a subspecies, hudson bay common eiders are poorly defined and not well studied (snyder 1941; freeman 1970; mendall 1980, 1986). the entire population of hudson bay common eiders is assumed to spend the whole year within the icy confines of hudson bay (snyder 1941; freeman 1970), unlike other subspecies of northern breeding eiders, which migrate to southern waters. in this paper, we compare clutch, egg and body size among populations of common eiders at three spatial scales: 1) among populations of common eiders breeding on the east coast of hudson bay, 2) between common eiders breeding in eastern and western hudson bay, and 3) between the hudson bay subspecies and the other two subspecies of common eiders breeding in eastern north america. methods fieldwork for this study was conducted in two general areas within hudson bay. the first site was a large area along the coast of south-eastern hudson bay and the belcher islands (figs. 1 and 2). data on egg size and clutch size in this region were collected during two intensive surveys of nesting eiders, one from 1985 to 1988, the other in 1997. nine nesting regions were visited in 1985-88, while only four regions in the belcher island archipelago were surveyed in 1997. clutch size data for these sites were extracted from fleming & mcdonald (1987), nakashima & murray (1988), mcdonald & fleming (1990) and robertson & gilchrist (1998). this population was estimated at 83 000 breeding pairs in the mid-1980s (nakashima & murray 1988), but has declined to an estimated 20 000 pairs by 1997 (robertson & gilchrist 1998). the other study area was at la pérouse bay, on the west coast of hudson bay, 30 km east of churchill, manitoba (fig. 1). data from this site were collected as part of an intensive study on the breeding biology of common eiders in 1991–93. the colony consists of approximately 400 female eiders nesting on the small freshwater islands of fig. 1. location and place names of common eider study areas in hudson bay. 87robertson et al. 2001: polar research 20(1), 85–94 the mast river delta (schmutz et al. 1983; robertson 1995a). egg and clutch size data for this site have been presented in robertson & cooke (1993) and robertson (1995b); the data presented in this paper have been reanalysed to keep the analyses between the two study areas consistent. because the colony at the mast river is small, it is likely that clutch size and egg size for a few females were measured in more than one year. this potential problem will artificially inflate sample sizes, but will not bias estimates of means. information for other subspecies (borealis and dresseri) was extracted from the literature and unpublished data provided by researchers. only clutches that were complete and being incubated were included in the analyses. egg volume (cm3) was calculated from measurements of egg length and maximum egg breadth using the equation found in guild (1974) and robertson & cooke (1993): vol. = 0.000515*length*breadth2. two analysis methods were used, recognizing that the size of eggs within a clutch are not independent samples. for data collected in eastern hudson bay in 1985-88 and the western hudson bay data, a mean egg size for the clutch was calculated and used in all analyses. during the 1997 survey in eastern hudson bay only one egg was measured from each clutch to reduce time spent on nesting islands. the egg that was measured was chosen at random (the egg closest to the north-east corner of the nest). both methods estimate mean egg size without bias and effectively control for the non-independence of the size of eggs within a clutch. the only difference is that by selecting one egg at random, both intraand inter-clutch variance are estimated, whereas using mean egg size, only inter-clutch egg size variance is estimated (i.e. the variance will be overestimated with the random eggs, making statistical tests more conservative). body size measurements were collected by the senior author at all locations. measurements, taken with vernier calipers (± 0.1 mm), were collected from eiders trapped for ringing (western hudson bay) or from birds shot by local inuit field assistants (eastern hudson bay). birds collected in eastern hudson bay where shot on the breeding grounds (in some cases directly off the nests) and so were representative breeders. head length, culmen 1 (culmen midline) and culmen 2 (total bill length), nostril extension, and total tarsus were taken according to mendall (1980, 1986) and dzubin & cooch (1992). results clutch size there were some differences in the clutch sizes among regions in eastern hudson bay (table 1). eiders at the most northerly and southerly sites fig 2. location and place names of common eider study areas in south-eastern hudson bay. 88 clutch, egg and body size variation among common eiders laid larger clutches. clutch size from sites in the middle of the study area did not differ (4.0 4.4). clutch sizes laid in western hudson bay were in the middle of the range of clutch sizes laid in eastern hudson bay (table 1). egg size within eastern hudson bay, there were significant differences among mean egg volumes measured at the different locations in 1985-86 (anova, f= 2.55, df = 7, 199, p = 0.016). egg volumes were larger in long island sound than all other regions (table 2); the sample size for this region was very small and may not be representative. no differences in mean egg volume were detected among the four regions of eastern hudson bay studied in 1997 (f = 1.43, df = 3, 224, p = 0.24). mean egg volumes for clutches from western hudson bay (table 2) were significantly smaller than clutches laid in eastern hudson bay (pooled mean 104.2 cm3 ± 7.2, n = 435) (t-test with unequal variances, t = 20.8, df = 754.7, p = 0.0001). body size in general, female common eiders in eastern hudson bay had longer tarsi and head lengths, and shorter nostril extensions than females in western hudson bay (table 3). similarly, males from eastern hudson bay had longer tarsi and head lengths and shorter nostril extensions and culmen 2 (total bill length) than males from western hudson bay (table 3). differences among subspecies clutch sizes were largest among sedentaria females. some populations of dresseri laid similar sized clutches (table 4), but some laid smaller ones. to the north, borealis females tended to lay smaller clutches. egg sizes were smaller in borealis than in sedentaria in eastern hudson bay, but not western hudson bay (table 4). only limited information is available for dresseri, but this subspecies lays similar or larger sized eggs than sedentaria (table 4). location latitude mean clutch size eastern hudson bay western hudson bay 1985-88a 1997b 1991-93c koktac river 59°15’ 4.8 ± 1.3 b (612) la pérouse bay, mb 58°45’ 4.3 ± 1.0 cd (323) sleeper islands 57°30’ 4.3 ± 1.4 cd 4.4 ± 1.1 c (2557) (412) nastapoka islands 57°00’ 4.1 ± 1.4 de (925) n. belcher islands 56°45’ 4.0 ± 1.3 e 4.0 ± 1.1 e (1140) (206) salikuit islands 56°15’ 4.2 ± 1.4 cde (649) s. churchill sound 56°00’ 4.1 ± 1.4 de 4.4 ± 1.2 c (876) (275) s. flaherty islands 55°45’ 4.0 ± 1.1 de 4.4 ± 1.0 c (1980) (419) long island sound 54°45’ 5.6 ± 1.0 a (113) table 1. mean clutch size (± 1 s.d.) for hudson bay common eiders (somateria mollissima sedentaria) across their range (see figs. 1 and 2 for locations). letters represent means not significantly different from one another (student-neuman-keuls post-hoc means test, anova, f = 34.4, df = 12, 10165, p = 0.0001). a data from fleming & mcdonald (1987), nakashima & murray (1988), mcdonald & fleming (1990). b data from robertson & gilchrist (1998). c data from robertson (1995b). 89robertson et al. 2001: polar research 20(1), 85–94 discussion clutch size comparisons of clutch sizes across studies are confounded by many factors that can influence measurements of clutch size. the timing of when clutch size is surveyed is important as partial clutches may be counted if the survey is too early. further, eiders, along with many other bird species, show significant annual variation in clutch sizes laid by individuals and populations (coulson 1999). a component of this annual variation is correlated with laying date (rohwer 1992). to minimize these sources of variation, at all sites in this study clutch size was measured during early to mid-incubation. although it is difficult to control for annual differences, we were fortunate in most years of this study because nesting was usually early and conditions were generally favourable (nakashima & murray 1988; robertson 1995b; robertson & gilchrist 1998). predation can greatly impact measures of clutch size, as many eggs are taken during the egg-laying stage (robertson & cooke 1993), especially by avian predators. differences in predation rates may be reflected in differences in clutch sizes among populations and among years. in spite of the fact that different sites were examined in different years, within hudson bay there was no clear pattern of clutch size variation among populations of common eiders. clutch sizes consistently averaged between 4 and 4.5 eggs. we are not sure why clutch sizes laid in long island sound were so large in 1985 at 5.6 eggs. intraspecific nest parasitism may have resulted in abnormally large clutches being incubated at this site (robertson et al. 1992; bjørn & erikstad 1994), and sample sizes were not large. in general, sedentaria laid slightly larger clutches then dresseri to the south and larger clutches than borealis to the north. other waterfowl species show a similar trend: clutch size tends to decrease in the northern portions of their range (dunn & macinnes 1987; rohwer 1992). individuals and populations that lay later in the season tend to lay smaller clutches (rohwer 1992). however, the relative timing of egg laying cannot explain the variation in clutch size laid between these subspecies of common eiders. in good to normal years, eiders nesting near the belcher islands do not begin egg-laying until mid to late june (nakashima & murray 1988; robertson & gilchrist 1998), similar to borealis eiders location latitude mean egg volume of clutch (cm3) eastern hudson bay western hudson bay 1985-86 1997 1991-93 koktac river 59°15’ 103.4 ± 5.8 b (72) la pérouse bay, mb 58°45’ 94.5 ± 5.5 c (323) sleeper islands 57°30’ 104.3 ± 4.7 b 103.2 ± 8.1 b (14) (61) n. nastapoka islands 57°15’ 102.2 ± 7.0 b (41) s. nastapoka islands 56°45’ 105.9 ± 5.7 b (10) n. belcher islands 56°45’ 103.0 ± 7.1 b 105.4 ± 7.0 b (20) (38) salikuit islands 56°15’ 105.5 ± 8.1 b (16) s. churchill sound 56°00’ 104.5 ± 7.5 b (74). s. flaherty islands 55°45’ 102.7 ± 5.2 b 105.9 ± 7.9 b (25) (55) long island sound 54°45’ 110.9 ± 8.0 a (9) table 2. mean egg volumes (± 1 s.d.) of hudson bay common eiders (somateria mollissima sedentaria) across their range (see figs. 1 and 2 for locations). letters represent means not significantly different from one another (student-neuman-keuls post-hoc means test). 90 clutch, egg and body size variation among common eiders in good nesting years far to the north (cooch 1965; prach et al. 1986; hgg unpubl. data). this is months later than dresseri nesting in new england and maritime canada, which begins in april for many populations. therefore, common eiders nesting in hudson bay tend to lay large clutches in spite of their late timing of breeding. common eiders rely exclusively on nutrients gathered and stored before laying for egg production and incubation (korschgen 1977; parker & holm 1990). eiders nesting in hudson bay may have more nutrient reserves during egg production because they do not undertake an extensive migration to the breeding grounds (freeman 1970; guild 1974). migrating individuals can utilize considerable nutrient reserves (berthold 1993). most populations of dresseri do not make extensive migrations either, and clutch sizes tend to be larger than borealis populations, which migrate from south-west greenland, newfoundland and the gulf of st. lawrence to the eastern canadian arctic (palmer 1976). populations of common eiders nesting in europe (s. m. mollissima) that do not undergo extensive migrations also show relatively large clutch sizes (means ranging from 4.2 to 5.0 eggs; scotland [milne 1974], the netherlands [swennen 1983], sweden [götmark & åhlund 1988], finland [hario & selin 1988], norway [erikstad et al. 1993]). similar to north america, borealis breeding on remote islands north of europe lay much smaller clutches (3.0 to 3.2, spitsbergen, ahlén & andersson [1970]; bjørn & erikstad [1994]). these populations undergo substantial migrations, wintering off the south coast of greenland, eastern north america or the barents sea (dement’ev & gladkov 1952). these comparisons must be made cautiously, however, as other factors, such as high incidents of nest parasitism in hudson bay among common eiders, may artificially inflate measures of clutch size, or high levels of partial clutch depredation in borealis may lower clutch size. egg size eiders nesting in western hudson bay laid smaller eggs. interestingly, there is no correlation between egg size and female body size or condition (laurila & hario 1988; swennen & van der meer 1992), so differences in body condition or size would not explain egg size differences among populations. one environmental component has been identified that explains some variation in egg size: robertson (1995b) showed that eiders laid smaller eggs when temperatures were cold during egg-laying. however, the average mean egg size difference between a very warm year and a very cold year was only 3% (robertson 1995b). the mean difference between east and west coast hudson bay common eiders was three times larger at 9%. nesting conditions were generally favourable in most years included in this study, so different annual environmental conditions were not likely to be a major source of variation in egg size between sites. egg size is highly repeatable in common eiders (laurila 1988; swennen & van der meer 1992) and likely to be highly heritable (rohwer 1992). therefore, we suggest that egg size differences among populations may reflect mostly genetic differences, although some portion of the variation (up to 3%) could be explained by the fact that eiders nesting on the east coast of hudson bay enjoy warmer temperatures at nesting. female eiders show natal philopatry to their breeding grounds (wakeley & mendall 1976; swennen 1990), so breeding populations of eiders are expected to show some genetic isolation (anderson et al. 1992; avise et al. 1992). indeed, tiedemann et al. (1999) found high levels of differentiation between colonies in maternally inherited mtdna sequences. however, male common eiders in europe disperse widely (swennen 1990). genetic isolation among breeding populations of eastern western hudson baya hudson bay t p females (n) 30 79 culmen 1 51.6 ± 2.6 52.0 ± 3.0 0.59 0.5552 culmen 2 71.4 ± 2.8 71.0 ± 2.4 0.75 0.4527 nostril extension 34.0 ± 2.0 35.9 ± 1.6 5.16 0.0001 head length 121.1 ± 2.3 118.6 ± 2.6 4.60 0.0001 tarsus length 66.4 ± 2.0 62.8 ± 2.0 8.38 0.0001 males (n) 10 9 culmen 1 55.8 ± 2.9 58.1 ± 3.5 1.59 0.1305 culmen 2 79.7 ± 3.3 82.8 ± 2.3 2.29 0.0353 nostril extension 40.5 ± 2.7 45.3 ± 2.2 4.20 0.0006 head length 128.8 ± 2.6 125.9 ± 2.5 2.35 0.0327 tarsus length 68.6 ± 1.3 66.2 ± 2.0 3.20 0.0053 a only 28 female and 8 male head measurements available for eastern hudson bay. table 3. morphometrics (mm, ± 1 s.d.) of common eiders in eastern and western hudson bay. culmen 1 (dzubin & cooch 1992) corresponds to mendall’s (1980, 1986) culmen midline and culmen 2 corresponds to total bill length. tarsus length is total tarsus (dzubin & cooch 1992). 91robertson et al. 2001: polar research 20(1), 85–94 common eiders in hudson bay could be maintained if male dispersal is restricted. suitable wintering habitat in the form of open water leads and polynyas is mostly restricted to south-eastern hudson bay, where large numbers of sedentaria common eiders are known to winter (freeman 1970; gilchrist & robertson 2000). it is assumed that these eiders breed in eastern hudson bay (freeman 1970). although they may winter in the belcher islands, common eiders from western hudson bay are suspected to winter off the landfast ice edge of the western coast, or in a large recurring polynya in roes welcome sound (abraham & finney 1986). potentially, eastern and western hudson bay common eiders are isolated from each other during winter, the time when pair bonds and, therefore, gene flow occurs. even if there is extensive nuclear gene flow among eiders breeding in hudson bay due to male dispersal, genetic isolation could be maintained if additive genetic variance for egg size is maintained on mitochondrial genes or the heterogametic chromosome. williams et al. (1994) suggested that there may be a genetic correlation between egg size and physiological and/or metabolic processes. if the genetic variance in egg size and covariance of egg size with other metabolic traits are occurring within the mitochondrial dna of females, then egg size will be solely maternally inherited. in this case, male dispersal will not result in exchange of genes influencing egg size, and genetic population structure for egg size would be solely influenced by female dispersal patterns (avise et al. 1992). body size as with egg size, eiders in eastern hudson bay subspecies location mean egg volume (cm3) mean clutch size source borealis devon island 94.6 ± 7.7 3.3 ± 1.0 prach et al. (1986) (158) (544) southampton island 90.2 ± 6.6 3.6 ± 1.2 h. g. gilchrist, unpubl data (262) (262) cape dorset 3.4 ± 1.0 cooch (1965) (1598) ungava bay 94.7 ± 6.2 3.6 ± 1.1 chapdelaine et al. (1986) (33) (2387) sedentaria la pérouse bay 94.5 ± 5.5 4.3 ± 1.0 this study (323) (323) la pérouse bay 96.1 4.1 ± 1.2 guild (1974) (298) (175) eastern hudson bay 104.2 ± 7.2 4.2 ± 1.3 this study (435) (9855) s. belcher islands 116 (97 139) 4.5 ± 1.4 freeman (1970) (84) (290) dresseri st. lawrence estuary 112.8 ± 7.4 3.7 ± 1.4 milne & reed (1974) (72) (1521) gulf of st.lawrence 4.3 ± 1.2 guignion (1968) (315) gulf of st.lawrence 4.0 ± 1.0 lewis (1939) (1131) new brunswick 3.6 ± 1.2 paynter (1951) (134) new brunswick 116.4 ± 10.2 4.4 (2-7) gross (1938) (45) (100) new brunswick 106.3 ± 7.2 4.0 ± 1.1 k. mawhinney, unpubl. data (642) (1921) maine 107.4 ± 8.2 3.9 ± 1.7 k. mawhinney, unpubl. data (736) (395) table 4. volumes of eggs and clutch sizes laid by common eiders in eastern north america. mean ± 1 s.d. (or range) with sample sizes in parentheses below. 92 clutch, egg and body size variation among common eiders were structurally larger. body size, similar to egg size, is highly heritable (boag & van noordwijk 1987), suggesting that there some isolation among eider populations breeding in hudson bay might be possible. head length and tarsus tend to be better indices of overall structural size than bill measurements (rising & somers 1989) and these were larger in eastern hudson bay. mixing with the smaller borealis race to the north may explain the smaller body size (and possibly egg size) of eiders nesting in western hudson bay. in developing his key, mendall (1980) tentatively identified some individuals collected from north-west hudson bay as borealis–sedentaria intergrades. a north—south cline along western hudson bay, with sedentaria to the south and borealis to the north is plausible. further, that cline may extend south-east, with the largest eiders occurring at the south-east corner of hudson bay. inuit hunters from the belcher islands mention that large brown eiders are found in the southern portion of the archipelago and smaller grey eiders are found at the northern portions of the belchers islands (nakashima & murray 1988). this cline may be maintained by male dispersal. genes for body size are known to be paternally inherited in waterfowl (larsson & forslund 1992; cooke et al. 1995), and clines are usually maintained by limited dispersal. movements of male eiders along the coast of hudson bay during winter are possible but probably restricted, to a degree, by ice and food availability. alternatively, the cline could be maintained by mate choice, if mates choose partners from their natal colony more often (but not exclusively) than expected at random (tiedemann et al. 1999). notwithstanding potential genetic differences, body size differences between eastern and western hudson bay may be due to different environmental conditions, especially during duckling growth (leafloor et al. 1998). the core of the breeding range of eiders in hudson bay is the south-eastern portion of the bay. therefore the western portion of hudson bay may represent marginal habitat for eiders and may be responsible for their slower growth and subsequent smaller adult body size (and possibly egg size). unlike head and tarsus length, bill measurements tend to be larger in western hudson bay. these differences are not as easily explained by differences in conditions during duckling growth. bill measurements are used in discriminating between the different subspecies of common eiders (mendall 1980, 1986). in general, dresseri individuals have longer culmen 2 (total bill length) and nostril extension measurements, and larger frontal lobes than sedentaria or borealis. interestingly, individuals, especially males, from western hudson bay had bill measurements like dresseri birds. in fact, using the keys provided in mendall (1986), the average male from western hudson bay was classified as a dresseri male. the key was based on small samples sizes for male sedentaria (n = 11) and may be insufficient to discriminate the subspecific status of eiders in hudson bay (mendall 1986). overall, common eiders breeding in hudson bay are large compared to other subspecies in eastern north america (freeman 1970). only v-nigra, which breeds and winters in the north pacific, is larger (palmer 1976). common eiders in hudson bay may have been under selective pressure to become larger. larger birds are better able to maintain homeothermy and they can survive longer during periods of stress (calder 1974; dunn & macinnes 1987). during the cold, short days of winter at these latitudes, larger body size may be advantageous for common eiders that do not migrate to southern waters. conclusion clutch sizes were relatively large and similar among populations of common eiders breeding in eastern and western hudson bay. as any differences in environmental conditions would be most likely be seen as differences in clutch size, differences in egg and body size among these populations suggest that there is some genetic population structuring of common eiders breeding in hudson bay. the population structure seen in eiders may be due to female natal philopatry and/or a lack of dispersal by males because of restricted wintering habitat in the ice. clearly, more work is needed to resolve the genetic relationships among eiders in hudson bay and studies are required to determine actual movements and breeding and wintering ground affinities of these populations. eider populations in this region have declined dramatically in recent years (robertson & gilchrist 1998) and an understanding of the genetic structure, affinities and movements of these populations is certainly needed to guide management recommendations in the future. 93robertson et al. 2001: polar research 20(1), 85–94 acknowledgements.—kim mawhinney kindly provided us with unpublished data. j.-å. nilsson provided helpful comments on an earlier draft. we thank the many individuals who helped us with the data collection. maureen kay prepared the figures. funding and logistical support was provided by the sanikiluaq hunters and trappers association, the canadian wildlife service (cws), the nunavut wildlife research trust, and the environmental studies revolving funds for the work in eastern hudson bay. gjr was supported by the natural sciences and engineering research council of canada (nserc), the northern scientific training program (department of indian affairs and northern development, diand), the frank m. chapman memorial fund and the association of canadian universities for northern studies while at la pérouse bay. the la pérouse bay tundra biology station is generously funded by nserc, diand, cws, the wildlife management institute, the central and mississippi flyway councils, ducks unlimited, the arctic goose joint venture, the manitoba department of renewable resources and the city university of new york. references abraham, k. f. & finney, g. h. 1986: eiders of the eastern canadian arctic. in a. reed (ed.): eider ducks in canada. can. wildl. serv. rep. ser. 47, 55–73. ahlén, i. & andersson, å. 1970: breeding ecology of an eider population on spitsbergen. ornis scand. 1, 83–106. anderson, m. d., rhymer, j. m. & rohwer, f. c. 1992: philopatry, dispersal, and the genetic structure of waterfowl populations. in b. d. j. batt et al. (eds.): ecology and management of breeding waterfowl. pp. 365–395. minneapolis: university of minnesota press. avise, j. c., alisauskas, r. t., nelson, w. s. & ankney, c. d. 1992: matriarchal population genetic structure in an avian species with female natal philopatry. evolution 46, 1084–1096. avise, j. c. & hamrick, j. l. (eds.) 1996: conservation genetics. london: chapman and hall. berthold, p. 1993: bird migration: a general survey. oxford: oxford university press. bjørn, t. h. & erikstad, k. e. 1994: patterns of intraspecific nest parasitism in the high arctic common eider (somateria mollissima borealis). can j. zool. 72, 1027–1034. boag, p. t. & van noordwijk, a .j. 1987: quantitative genetics. in f. cooke & p. a. buckley (eds.): avian genetics. pp. 45–78. london: academic press. calder, w. a., iii 1974: consequences of body size for avian energetics. in r. a. paynter (ed.): avian energetics. pp. 86–144. cambridge, ma: nuttall ornithological club. chapdelaine, g., bourget, a., kemp, w. b., nakashima, d. j. & murray, d. j. 1986: population d’eider à duvet près des côtes du québec septentrional. (the common eider population of the northern québec coast.) in a. reed (ed.): eider ducks in canada. can. wildl. serv. rep. ser. 47, 39–50. cooch, f. g. 1965: the breeding biology and management of the northern eider (somateria mollissima borealis) in the cape dorset area, northwest territories. canadian wildlife service wildl. manage. bull. ser. 2, no. 10. cooch, e. g., lank, d. b., rockwell, r. f. & cooke, f. 1991: long-term decline in body size in a snow goose population: evidence of environmental degradation? j. anim. ecol. 60, 483–496. cooke, f., rockwell, r. f. & lank, d. b. 1995: the snow geese of la pérouse bay: a study in natural selection. oxford: oxford university press. coulson, j. c. 1999: variation in clutch size of the common eider: a study based on 41 breeding seasons on coquet island, northumberland, england. waterbirds 22, 225–238. cramp, s. & simmons, k. e. l. 1977: the birds of the western palearctic. vol. 1. oxford: oxford university press. dement’ev, g. p. & gladkov, n. a. 1952: birds of the soviet union. vol. iv. (translated from russian by the israel program for scientific translations, jerusalem, 1967.) dunn, e. h. & macinnes, c. d. 1987: geographic variation in clutch size and body size of canada geese. j. field ornithol. 58, 355–371. dzubin, a. & cooch, e. g. 1992: measurements of geese: general field measurements. sacremento: california waterfowl association. erikstad, k. e., bustnes, j. o. & moum, t. 1993: clutch-size determination in precocial birds: a study of the common eider. auk 110, 623–628. fleming, b. & mcdonald, m. 1987: a nest census and the economic potential of the hudson bay eider in the southern belcher islands, n.w.t: a report prepared for the department of indian and northern affairs, gnwt region. project no. 176057. sanikiluaq, canada: municipality of sanikilauq. freeman, m. m. r. 1970: observations on the seasonal behaviour of the hudson bay eider (somateria mollissima sedentaria). can. field-nat. 84, 145–153. gilchrist, h. g. & robertson, g. j. 2000: observations of marine birds and mammals wintering at polynyas and ice edges in the belcher islands, nunavut, canada. arctic 53, 61–68. götmark, f. & åhlund, m. 1988: nest predation and nest site selection among eiders somateria mollissima: the influence of gulls. ibis 130, 111–123. gross, a. o. 1938: the eider ducks of kent’s island. auk 55, 387–400. guignion, d. 1968: clutch size and incubation period of the american eider (somateria mollissima dresseri) on brandypot island. nat. can. 95, 1145–1152. guild, b.l. 1974: the breeding biology of the hudson bay eider at la pérouse bay, manitoba. m.sc. thesis. wright state university, ohio. hario, m. & selin, k. 1988: thirty-year trends in an eider population: timing of breeding, clutch size, and nest site preferences. finn. game res. 45, 3–10. korschgen, c. e. 1977: breeding stress of female eiders in maine. j. wildl. manage. 41, 360–373. larsson, k. & forslund, p. 1992: genetic and social inheritance of body and egg size in the barnacle goose (branta leucopsis). evolution 46, 235–244. laurila, t. 1988: the role of genetic factors on clutch size and egg dimensions in the common eider somateria mollissima. finnish game res. 45, 11–18. laurila, t. & hario, m. 1988: environmental and genetic factors influencing clutch size, egg volume, date of laying and female weight in the common eider somateria mollissima. finn. game res. 45, 19–30. leafloor, j. o., ankney, c. d. & rusch, d. h. 1998: environmental effects on body size of canada geese. auk 115, 94 clutch, egg and body size variation among common eiders 26–33. lewis, h. f. 1939: size of sets of eggs of the american eider. j. wildl. manage. 3, 70–73. mcdonald, m. & fleming, b. 1990: development of a community-based eider down industry in sanikiluaq: resource management and business strategies: a report prepared for the canada-northwest territories economic development agreement. project no. 561 510. sanikiluaq, canada: municipality of sanikilauq. mendall, h. l. 1980: intergradation of eastern american common eiders. can. field-nat. 94, 286–292. mendall, h. l. 1986: identification of eastern races of the common eider. in a. reed (ed.): eider ducks in canada. can. wildl. serv. rep. ser. 47, 82–88. milne, h. 1974: breeding numbers and reproductive rate of eiders at the sands of forvie national nature reserve, scotland. ibis 116, 135–154. milne, h. & reed, a. 1974: annual production of fledged young from the eider colonies of the st. lawrence estuary. can. field-nat. 88, 163–169. nakashima, d. j. & murray, d. j. 1988: the common eider (somateria mollissima sedentaria) of eastern hudson bay: a survey of nest colonies and inuit ecological knowledge. environmental studies revolving funds rep. 102. van noordwijk, a. j., van balen, j. h. & scharloo, w. 1988: heritability of body size in a natural population of the great tit (parus major) and its relation to age and environmental conditions during growth. genet. res. camb. 51, 149–162. palmer, r. s. 1976: handbook of north american birds. vol. 3. new haven: yale university press. parker, h. & holm, h. 1990: patterns of nutrient and energy expenditures in female common eiders nesting in the high arctic. auk 107, 660–668. paynter, r. a., jr. 1951: clutch-size and egg mortality of kent island eiders. ecology 32, 497–507. prach, r. w., smith, a. r. & dzubin, a. 1986: nesting of the common eider near hell gate—cardigan strait polynya, 1980-1981. in a. reed (ed.): eider ducks in canada. can. wildl. serv. rep. ser. 47, 127–135. rising, j. d. & somers, k. m. 1989: the measurement of overall body size in birds. auk 106, 666–674. robertson, g. j. 1995a: factors affecting nest site selection and nesting success in the common eider somateria mollissima. ibis 137, 109–115. robertson, g. j. 1995b: annual variation in common eider egg size: effects of temperature, clutch size, laying date, and laying sequence. can. j. zool. 73, 1579–1587. robertson, g. j. & cooke, f. 1993: intraclutch egg-size variation and hatching success in the common eider. can. j. zool. 71, 544–549. robertson, g. j. & gilchrist, h. g. 1998: evidence of population declines among common eiders breeding in the belcher islands, northwest territories. arctic 51, 378–385. robertson, g. j., watson, m. d. & cooke, f. 1992: frequency, timing and costs of intraspecific nest parasitism in the common eider. condor 94, 871–879. rockwell, r. f. & barrowclough, g. 1987: gene flow and the genetic structure of populations. in f. cooke & p. a. buckley (eds.): avian genetics. pp. 226–255. london: academic press. rohwer, f. c. 1992: the evolution of reproductive parameters in waterfowl. in b. d. j. batt et al. (eds.): ecology and management of breeding waterfowl. pp. 486–539. minneapolis: university of minnesota press. schmutz, j. m., robertson, r. j. & cooke, f. 1983: colonial nesting of the hudson bay eider duck. can. j. zool. 61, 2424–2433. snyder, l. l. 1941: on the hudson bay eider. occas. pap. r. ont. mus. zool. 6, 1–7. swennen, c. 1983: reproductive output of eiders somateria mollissima on the southern border of its breeding range. ardea 71, 245–254. swennen, c. 1990: dispersal and migratory movements of eiders somateria mollissima breeding in the netherlands. ornis scand. 21, 17–27. swennen, c. & van der meer, j. 1992: variation in egg size of common eiders. ardea 80, 363–373. tiedemann, r., von kistowski, k. g. & noer, h. 1999: on sex-specific dispersal and mating tactics in the common eider somateria mollissima as inferred from the genetic structure of breeding colonies. behaviour 136, 1145–1155. wakeley, j. s. & mendall, h. l. 1976: migrational homing and survival of adult female eiders nesting in maine. j. wildl. manage. 40, 15–21. williams, t. d. 1994: intraspecific variation in egg size and composition among birds: effects on offspring fitness. biol. rev. camb. philos. soc. 68, 35–59. williams, t. d, lank, d. b., cooke, f. & rockwell, r. f. 1994: fitness consequences of egg-size variation in the lesser snow goose. oecologia 96, 331–338. winkler, d. w. & walters, j. r. 1983: the determination of clutch size in precocial birds. curr. ornithol. 1, 33–68. shrimp trawl catches and stomach contents of redfish, greenland halibut and starry ray from west greenland during a 24-hour cycle s b r e n anker pedersen pedersen, s.a. 1994: shrimp trawl catches and stomach contents of redfish, greenland halibut and starry ray from west greenland during a 24-hour cycle. polar research 13(2), 183-196 a total of 179 redfish (sebastes spp.), 495 greenland halibut (reinhardtius hippoglossoides) and 133 starry ray (raja radiufa) stomachs were collected from the catch in four bottom trawl hauls carried out at 6-hour intervals on a shrimp fishing ground off west greenland in september 1991. between 90 and 96% of the total catch in each of the four trawl hauls consisted of northern shrimp (pandalus borealis). the fish catches were small and dominated by redfish, greenland halibut, starry ray and polar cod (boreogadus saida). the stomach contents of redfish consisted of crustaceans (mysiids, hyperiids and copepods) followed by cephalopods, northern shrimp and redfish. fish (mainly redfish), cephalopods and northern shrimp were the most important stomach content of greenland halibut. the stomach content of starry ray consisted mainly of northern shrimp and redfish. plots of redfish and shrimp sizes found in the stomachs of greenland halibut and starry ray versus predator size showed only weak associations indicating that availability overruled the importance of size-dependent prey preference. the present study indicates that redfish, greenland halibut and starry ray feed throughout the 24-hour cycle with no clear diel feeding rhythms. s. a . pedersen, greenland fisheries research itastifute, tagetasuej 135, i . f v . , dk-2200 copenhagen n, denmark n introduction during the last two decades the offshore fishery for northern shrimp (pandalus borealis) in the davis strait has been one of the largest fisheries for this species in the world. in 1992, the nominal catch of shrimp in the offshore area of west greenland south of 71"n increased to about 63,000 tons the highest level in the history of this fishery (anon. 1994). large numbers of fish, mainly redfish (sebastes spp.), greenland halibut (reinhardtius hippoglossoides) , and polar cod (boreogadus saida), but also starry ray (raja rad iata) and long rough dab (hippoglossoides platessoides) and others, are caught and discarded in the west greenland shrimp fishery (pedersen & kanneworff in press). predation is probably the main source of nat ural mortality in shrimp populations, and north ern shrimp has been described as a major food item for atlantic cod (gadus morhua), green land halibut, redfish and eelpouts in the west greenland waters (horsted & smidt 1956; horsted & smidt 1965; smidt 1969). studies of the feeding habits of redfish, greenland halibut and starry ray on west greenland shrimp grounds have recently been described by pedersen & riget (1993) and pedersen (in press). these studies analyse the stomach contents of fish collected mainly during the day. however, die1 feeding rhythms are common in many teleosts and diel feeding patterns have been described for tropical and temperate fishes (helfman 1993). in order to assess the daily rate of food consumption in fish populations, it is essential to have information about the diel variations in their feeding habits (eggers 1977; pennington 1985; wootton 1990; jarre et al. 1991; dos santos & jobling 1992). this paper compares shrimp trawl catches and stomach contents of redfish, greenland halibut and starry ray collected during a 24-hour cycle. materials and methods a total of 179 redfish, 495 greenland halibut and 133 starry ray stomachs were collected from four bottom trawl hauls carried out at 6-hour intervals 26 and 27 september 1991. the four trawling periods were night (2.ocr3.00 a.m.), after sunrise (8.00-9.00 a.m.), day (2.00-3.00 p m . ) and after sunset (7.45-8.45 p.m.) (table 1, fig. 1). the 184 s. a . pedersen night night i i 0 3 8 9 12 15 18 11 24 hour fig. 1. allocation of trawls to time of day (local time) and periods of darkness, twilight and daylight at the 24 h station, 26-27 september 1991. sunrise (=7.19 a m . ) and sunset (=7.10 p m . ) are marked with triangles. bottom trawling was carried out by m/tr paa miut (722 grt) on a fixed station north of store hellefiskebanken at depths between 450-500 m (fig. 2). this area is important for the commercial shrimp fishery. the stomach sampling was per formed during a stratified-random trawl survey for shrimp, and the position of the sampling station was chosen mainly because of a good catch of shrimp and fish. the gear used was a skjervoy 3000/20 shrimp-trawl with bobbin gear and a double-bag with 44 mm mesh size in the cod-end. the duration of the hauls was held as close as possible to 60 minutes at a speed of 2.5 knots. the wing spread, trawl opening and headline height were about 24 m, 286 m2 and 15 m, respect ively. the vertical temperature and salinity profile on the fishing station were recorded using a sea bird sbe 9-01 ctd. from the surface to about 70 m, the temperature decreases from about 3 to -0.7"c and increases thereafter to about 2.6"c at the bottom (fig. 3). a more detailed description of the physical oceanography of west greenland can be found in buch (1990). the sampling strategy was to collect stomachs from different length-groups of predators in the catch in each haul. fish with no signs of regur gitation from the stomach were individually tagged and frozen (< 18°c) for later examina tion. the carapace length (cl) of northern shrimp was measured by slide calliper to the near est 0.1 mm on subsamples from the catch during the day haul (2.00 p.m.) and the night haul (2.00 a.m.). during each of the four hauls, each total catch (or a subsample) of all species of fish was measured (total length) to the nearest cm below. in the laboratory the stomach content was identified to the lowest possible taxon. the degree of digestion of fish prey (dod) was judged by a six point scale and of invertebrate prey by a four point scale as proposed by bromley & last (1990). each food category was counted and weighed wet to nearest 0.1 g. excess liquid was removed mechanically. whenever the digestive condition permitted, carapace and/or pleuron length of pandalus borealis were measured with an accu racy of 0.1 mm. fish prey were measured to the nearest mm total length and/or the length of the vertebral column was measured. in cases where it was only possible to measure the length of the pleuron and vertebral column, the length of the carapace and total fish length were calculated as described by pedersen & riget (1993). the relative importance of individual prey taxa was assessed with indices of frequency of occur rence, number and weight (clark 1985) and a stomach fullness index (bowering & lilly 1992): frequency of occurrence: the number of stomachs in which a prey item occurred was expressed as a percentage of the total number of stomachs investigated. number: the number of each prey item in table i. number, size range, mean size and percent empty stomachs of redfish, greenland halibut and starry ray stomachs analysed for food by time of collection from the sampling station off west greenland. redfish greenland halibut starry ray per per per number size mean cent number size mean cent number size mean cent time of of range size empty of range size empty of range size empty collection fish (cm) (cm) stomachs fish (cm) (cm) stomachs fish (cm) (cm) stomachs ____ ~ ~~ ~~ ~ 2.00am 47 7-21 12.6 45% 87 11-46 24.7 13% 30 1 u 4 31.2 13% 8.00am 43 7-27 14.6 61% 126 10-44 26.9 25% 28 23-44 32.2 7% 2.00pm 43 6-30 14.1 44% 188 10-43 26.5 33% 34 1 4 4 7 26.6 3% 7.45 pm 46 7-32 13.5 46% 94 1&40 24.9 21% 41 w 6 24.0 22% all 179 7-32 13.7 49% 495 10-46 26.0 25% 133 9-47 27.5 12% shrimp trawl catches and stomach contents of redfish, halibut and starry ray 185 fig. 2. location of the sampling station and major physiographic features off west 70"n 68"n 66"n i i 39' y m' / greenland. the sampling 50. station is marked by a star. 60"w 55"w 5o"w all stomachs in the sample was expressed as a percentage of the total number of food items in weight: the weight of each prey item in all stomachs in the sample was converted to a per centage of the weight of the total stomach con tents in the sample. the mean partial fullness index of prey was calculated as: all stomachs in the sample. 1 w.. p f i , = e + x 104 n j = , l i where wij is the weight of prey i in fish j , l, is the length of fish j , and n is the number of fish in the 186 s. a . pedersen 0 50 100 150 e 200 s & 250 300 n a 350 400 450 temperature ("c.) 1 0 1 2 3 fig. 3. temperature profile on the sampling station off west greenland 27 september 1991. sample. the mean total fullness index (tfi) was calculated by adding values of mean partial full ness index. each index has its advantages and limitations, depending on the question addressed (hyslop 1980). i used pfi and tfi to emphasise the weight of prey in relation t o predator size and to examine stomach content variability related to predator size and sampling time. plots of the frequency distributions of the tfi data revealed that the tfi of redfish, greenland halibut and starry ray looked far from normal or log-normal distributed, but was rather exponential distributed. there fore, the kruskal-wallis rank test, a non parametric method, was used to test for differences between the median tfi in relation to fish size and sampling time. chi-square ( y ) tests (2 x 2 and p x q contingency tables) were used to test for difference in the probability of an individual having an empty stomach by time of day, and for difference in the size frequency dis tributions of shrimp and fish from the trawl catches by time of day (campbell 1975). results trawl catches between 90 and 96% of the total catch in each of the four trawl hauls consisted of northern shrimp (table 2). there were small variations in the cpues of shrimp between the hauls and no clear die1 effect. the fish catches were small and dom inated by redfish, greenland halibut, starry ray and polar cod. most redfish were taken in the day haul a t 2.00 p.m. and most greenland halibut and table 2. catch (kg h ' ) of shrimp and fishes by haul on the sampling station off west greenland, 2 6 2 7 september 1991. catch (kg h-i) by hauling time species 2.00 am 8.00 am 2.00 pm 7.45 pm shrimp redfish greenland halibut starry ray polar cod eelpouts sea snails long rough dab sculpins atlantic cod roughhead grenadier squids others 1100.7 41.8 14.8 1 1 . 1 2.5 1.4 1.0 0.5 0.8 0.2 0.2 0.1 0.0 1466.5 38.2 30.0 13.2 6.3 1.5 2.3 1.0 0.4 1.5 0.0 1274.0 62.4 46.4 12.1 7.9 2.3 2.7 1.1 1.4 0.5 0.6 1465.0 22.6 18.4 12.0 3.2 1 . 1 1 . 1 0.2 0.5 0.5 0.0 shrimp trawl catches and stomach contents of redfish, halibut and starry ray 187 fig. 4. size-frequency distributions of northern shrimp caught during a day and a night haul o n the sampling station off west greenland. 16 1 2 8 4 % o 1 2 8 4 0 northern shrimp day (2.00 pm) n=570 northern shrimp night (2.00 am) n=521 r i rl il l polar cod were taken in both day hauls at 8.00 a.m. and at 2.00 p.m. (table 2). there was a significant difference (xzis = 103.4, p < 0.qol) between the day and night haul in the size-fre quency distributions of shrimp the prominent modes occurred at 21-22 mm cl and 24-25 mm cl in the day haul, whereas the lower mode was less represented in the night haul (fig. 4). for the fishes in the catch there were minor differences in length-frequency distributions by the time of day, and they were combined (fig. 5). general description of diet during the stomach sampling very few individuals of greenland halibut and starry ray showed evi dence of regurgitation or stomach eversion. how ever, the majority of the redfish in the trawl catches had their stomachs everted, and only indi viduals with intact stomachs as judged by eye were selected. therefore, the reliability of stomach content data from the redfish are questionable. the percentages of empty stomachs regardless of 188 s. a . pedersen 25 20 1s 10 s 0 20 15 1c ! % f l! 1f i l ! 11 n polar cod redfish n=6419 1 greenland halibut n-1242 starry ray n=l43 total length (cm) fig. 5. combined size frequency distributions of the dominant fish species caught during the four haul on the sampling station off west greenland. shrimp trawl catches and stomach contents of redfish, halibut and starry ray 189 fish length during the four sampling times varied from 44 to 61% for redfish, from 13 to 33% for greenland halibut and from 3 to 22% for starry ray (table 1). for redfish x2-tests showed that there was no significant (p > 0.05) difference in the probability of an individual having an empty stomach between the different sampling times (tested in pairs). for greenland halibut there was a significant higher probability of an individual having an empty stomach during the day at 2.00 p.m. compared to both the night samples at 2.00 a.m. and 7.45 p.m. k2, = 12.6, p < 0.001 and xz1 = 4.2, p < 0.05). for starry ray the probability of an individual having an empty stomach was significantly different between all the sampling times and, therefore, there was a significant lower probability of an individual having an empty stomach during the day (table 1). the food of redfish, greenland halibut and starry ray were identified to 23 taxonomic units (table 3). the food of redfish consisted of the crustaceans (mysiids, hyperiids and copepods) followed by cephalopods, northern shrimp and redfish. shrimp had a low occurrence (2.2%) in the redfish stomachs but was important by weight (39%). fish, cephalopods and northern shrimp were the most important food for greenland hali but. of the fish prey, redfish was the most impor tant (33% by occurrence and 46% by weight) but polar cod and greenland halibut were also important. the food of starry ray consisted of mainly northern shrimp and redfish. table3. prey items from stomachs of redfish, greenland halibut and starry ray caught on the sampling station off west greenland, 26-27 september 1991. percentages of occurrence ( 0 ) , numbers (n), and weight (w) and mean partial fullness indices (pfi). (0.0 indicates presence but percentage <0.05; 0.00 indicates pfi < 0.005). prey items redfish greenland halibut starry ray o ( % ) n(%) w(%) pfi o ( % ) n(%) w(%) pfi o ( % ) n(%) w(%) pfi polychaeta cephalopoda crustacea (total) copepoda mysidacea isopoda gammaridea hyperiida parathemisto sp. unid. hyperiida euphausiacea natantia pandalus borealis pandalus montagui pandalus sp. crangonidae others and unid. unidenti. crustacea echinodermata pisces (total) cottidae boreogadus saida reinhardtius hipp. sebastes sp. others and unid. unidentified + slime total* 2.2 14.5 1.1 6.7 0.6 4.5 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 33.0 179 8.9 88.7 11.1 37.8 4.4 22.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 44 10.3 83.7 2.6 27.7 0.0 10.0 0.0 17.4 0.0 21.7 0.0 3.3 4.3 4.3 39.7 0.2 0.04 6.1 0.71 15.8 0.08 0.6 0.29 1.2 0.00 2.8 0.18 3.2 0.00 0.4 0.07 4.0 0.01 0.4 0.02 3.6 0.02 0.8 0.03 0.2 0.01 36.8 3.0 0.4 0.01 32.8 1.2 0.75 495 0.3 8.5 32.0 3.2 1.6 5.6 8.0 0.5 6.4 0.5 4.8 1.1 0.3 59.7 5.3 0.5 50.9 3.0 371 0.0 11.4 23.1 0.0 0.3 0.3 1.1 0.1 13.9 0.0 7.0 1.1 0.0 64.5 14.3 0.9 45.6 3.7 1164 0.00 0.8 0.30 0.8 0.35 33.1 0.00 3.8 0.01 11.3 0.8 1.5 0.03 0.08 0.8 0.00 0.12 12.8 0.00 0.08 11.3 0.02 3.8 0.01 0.8 0.8 0.80 15.8 1.5 0.14 0.01 0.59 14.3 0.06 0.8 1.44 133 81.4 17.8 32.5 3.8 0.6 12.1 10.8 3.8 18.4 2.5 15.9 157 1.0 0.06 0.0 0.00 68.3 1.34 0.0 0.02 0.7 0.06 0.0 0.03 0.0 0.01 0.0 0.00 25.3 0.45 34.9 0.64 1.8 0.01 4.7 0.06 0.9 0.06 0.3 0.00 30.1 0.44 4.4 0.05 23.1 0.33 2.6 0.06 686.5 1.86 * totals are numbers of stomachs, numbers of prey items, prey wet mass (g), and mean total fullness index (tfi). 190 s . a. pedersen influence of predator size and sampling time redfish. the relative importance of the prey changed with predator size (fig. 6). mysiids, hyp eriids and copepods dominated the stomach con tent of small redfish (<15 cm), whereas shrimp, cephalopods and redfish became more important in the stomachs of larger redfish (>14cm). the mean total fullness index (tfi) was generally highest for the smallest redfish (5-9 cm). no diel feeding rhythms could be revealed from the fre quency distributions at the different digestion stages of the prey and the d o d of the prey items was generally high (>2) both day and night. due to the low number of redfish stomachs examined in each size group, the relatively high frequency of empty stomachs and the low reliability of the redfish stomach content data in general, no tests for variation in mean tfi by fish size or sampling time were made. greenland halibut. for small greenland halibut (<15 cm) hyperiids was the dominating food whereas cephalopod, redfish, shrimp and polar cod were the dominating stomach content of big ger greenland halibut (>14cm) (fig. 6). from visual inspection of fig. 6, the tfi of size group 15-24 cm is higher compared to the other size groups at all sampling times. a kruskal-wallis test showed significant (p < 0.05) differences in the median tfi between the fish size groups at 2.00a.m.(n=86,h=25.20,p<0.001)and2.00 p.m. (n = 188, h = 12.04, p = 0.007), but not at 8.00 a.m. (n = 126, h = 7.10, p = 0.07) and7.45 p m . (n = 94, h = 1.90, p = 0.59). therefore, tests for differences in the median tfi between the four sampling times were performed for each size group. there were no significant diel dif ferences in the median tfi for the 5-14 cm size group (n = 52, h = 2.30, p = 0.51) or for the 35 44 cm size group (n = 40, h = 4.82, p = 0.19), whereas each of the two size groups 15-24 and 25 34 cm showed significant diel difference in median tfi (n = 102, h = 15.30, p = 0.002, and n = 300, h = 16.17, p = 0.001, respectively) due to significant higher median tfi at 2.00 a.m. (tests without the 2.00 a.m. data showed no significant differences). the higher tfi in the night sample may indicate a higher frequency of feeding during the night. however, comparisons of the frequency distributions at the different digestion stages of invertebrate and fish prey at the time of sampling low digestion stages at night (fig. 7). a visual examination of dod data of each prey type by time of sampling revealed no evidence for a diel feeding rhythm. the size-frequency distributions of redfish and shrimp in the greenland halibut stomachs showed peaks at 7 cm and 23 mm, respectively (figs. 8 and 9). a total of 10 polar cod found in the stomachs could be estimated to length from 8 to 16 cm (six were 11-12 cm). plots of redfish and shrimp sizes vs predator size showed only weak associations (r = 0.17, n = 86 and r = 0.12, n = 23, respectively) indicating that availability over ruled the importance of size-dependent prey pref erence. redfish was prey for greenland halibut above 15 cm, and although all sues of greenland halibut fed on small redfish there seemed to be a maximum size limit of redfish taken which increases with predator size (fig. 10). starry ray. shrimp was the dominating stomach content of starry ray in all size groups (fig. 6). there was a weak trend of redfish being more important in starry ray above 24 cm. there were no significant differences in the median tfi between the fish size groups at any of the sampling times, and the kruskal-wallis test with all sizes of fish included showed no significant differences in the median tfi between sampling time (n = 126, h = 4.53, p = 0.21). a total of 23 shrimp found in the stomachs could be estimated to cara pace length from 4 to 33 mm (fig. 11). a total of 10 redfish could be estimated to lengths from 6 to 10 cm (three were 6.5 cm and three were 9.5 cm). plots of the frequency distributions of the prey digestion stages showed no diel trends, and the d o d of the prey items was generally high (>2) both day and night. discussion the composition of the demersal fish community was quite stable throughout the 24-hour period at the locality studied. the high catch of northern shrimp, the order of fish importance (kg/hour) and the size-frequency distributions of both shrimp and fishes found in this study are normal for this fishing depth and location (pedersen & kanneworff in press). die1 changes in light conditions in the sea are known to influence behaviour and vertical dis showed no evidence of a higher frequency of the tribution of many species of fish and invertebrates shrimp trawl catches and stomach contents of redfish, halibut and starry ray 191 redfish 2.00 am 1.5 1 .o 0.5 0.0 1.5 1 .o 0.5 0.0 1 .o 0.5 0.0 food o l h , l o w 0 e l 3 1 i i h j p a & length (cm) encephalo oda copeposa m euphauslacea m ~ 9 hyperllda 88 m y s l d a c e a i pandalus sp. u s e b a s t e s sp. um unld. crustacea greenland halibut i 7.45 pm length (cm) starry ray 2.00 am i 31 y" 1 2.00pm 3 i 7.45 pm length (cm) food e23 cephalopoda hyperlido pandalus sp. tzza other crustacea food pandalus sp. boreogadus salda other crustacea a sebastes sp. 0 sebasles sp. other+unld. fish czzu other+unld. fish fig. 6. mean partial fullness index (pfi) for different food items in stomachs of redfish, greenland halibut and starry ray by predator length and sampling time from the sampling station off west greenland. sample sizes are given at the top. 192 s. a. pedersen invertebrate 9% n = 3 7 2.00am 20 4b 0 60 40. 20. "1 2.00 pm n = 7 7 n = 5 1 20 41 0 1 2 3 digestion stage fish 40 2 0 0 60 4 0 20 0 a0 60 40 za 0 60 40 2c c n = 5 3 8.00 am n = 5 3 2.00 pm u=82 7.45 pm n=49 -r 1 2 3 4 5 6 digestion stage fig. 7. the frequency of invertebrate and fish prey at the various stages of digestion in greenland halibut stomachs by sampling time from the sampling station off west greenland (digestion stages from bromley & last (1990). 1 = intact, no obvious digestion, for invertebrates; 4 = only fragments remaining and for fish 6 =just bones). down to depths of several hundred metres (longhurst 1976). thus, diel patterns in stomach contents of fish might be attributable to changes in foraging activity or to changes in availability of the prey. in this study minor diel variation in the cpue of shrimp was seen; however, in shrimp fishery the highest mean cpues of shrimp are normally taken during daytime (smidt 1978). dif ferences in the size-frequency distributions of shrimp in the catches between the day and the night haul are also normally seen due to an upward vertical migration during night-time of mainly the intermediate shrimp sizes (18-22 mm) (d.m. carlsson pers. comm.). therefore, the shrimp size-frequency distribution from the day time haul probably gives the best representation of the shrimp sizes available for the fish predators. in this study there was a trend of more greenland halibut and polar cod being caught in the daytime hauls. in august 1992, a study of the vertical dis tribution of shrimp and fishes during a 24-hour cycle, performed by pelagic trawling in different depth strata in the same area as the present study, found clear upward migrations of shrimp, small greenland halibut and polar cod from day to night-time (o.a. jwgensen pers. comm.). how ever, the redfish, which was only taken in the depth stratum closest to the bottom (2cl30m above the bottom) both day and night, showed minor diel vertical migrations. the diet of redfish, greenland halibut and starry ray as well as the change in prey type preference with predator size are generally similar to earlier findings from stomach contents of redfish, greenland halibut and starry ray in west greenland waters in autumn (pedersen & riget 1993; pedersen in press). however, compared to the earlier findings the mean tfi of the redfish stomachs in this study were lower. the tem peratures at the sampling station are close to the lower temperature limit for the distribution of redfish which is about 2°c (pedersen & kan neworff 1994). this may be the reason why the small plankton eating redfish (<20cm) are in a low status of feeding and why they are distributed close to the bottom below the cold water in the upper 150m of the water column dominated by polar water (fig. 3). the mean tfi of greenland halibut collected during daytime showed levels similar to earlier findings whereas the mean tfi of the night-time collected were higher (pedersen & riget 1993). from the tfi data of starry ray shrimp trawl catches and stomach contents of redfirh, halibut and starry ray 193 fig. 8. combined size frequency distributions of 0 redfish in stomachs of 0 p 5-g greenland halibut from the sampling station off west greenland. no indication of a sampling time effect was seen. for greenland halibut there was a higher fre quency of empty stomachs during the day whereas for starry ray there was a higher frequency of empty stomachs during the night. the later results may indicate mainly night-time feeding for green land halibut and mainly daytime feeding for starry ray. however, comparisons of the frequency of dod of the dominating prey items by sampling time gave no clear evidence of diel feeding rhythms for either redfish, greenland halibut or starry ray. there are four likely explanations for this: (1) because of the individual variability in feeding the number of stomachs analysed and, therefore, the number of prey items examined are far too low to detect any die1 pattern although bnnnnn . w m u m w carapace length (mm) fig. 9. combined size-frequency distributions of northern shrimp in stomachs of greenland halibut from the sampling station off west greenland. 1 total length (cm) it might exist; (2) the method of freeze storage and thawing the dod of the different prey items before analysing blurs the possibility of detecting diel feeding rhythms due to secondary decompo sition of otherwise fresh prey; (3) because of large variability in space and time of the feeding activities, one 24-hour cycle from one station is insufficient t o detect die1 feeding; and (4) the large variability in the time required for predators to digest small and large prey items. according to dos santos & jobling (1991), it may take 3-5 days for a herring or capelin t o be evacuated from the stomach of a cod at the temperatures which exist in the area considered in the present study. if it takes several days for the predators in this study to digest a relatively large prey, and additional prey are consumed before the stomach is emptied, then a distinct diel feeding pattern based on analyses of mean tfi may be hard to detect. even looking for changes in stage of digestion may not be very revealing, unless there is a strong die1 pattern in feeding and one has a large sample size, because each prey will be in a given stage of digestion for many hours, and the duration within each stage may vary with the sizes of the predator and the prey and the quantity of other prey in the stomach (g. lilly pers. comm.). according t o wootton (1990), there may be large variations in the feeding activities of teleosts between days, areas and seasons. the higher tfi and lower proportion of empty stomachs found for greenland halibut during night-time may be 194 s. a. pedersen i 1 1 1 / 1 0 /. e e * * t 3 ; : * o o o 0 ' 0 0 n : s d " n r o * @ o * * 0 .o 0 1 0 0 " 5 o o o 10 20 30 40 predator length (cm) explained by higher foraging activity, larger ver tical migration and thus lower catches of fish with empty stomachs during bottom trawling at night time. however, other studies of feeding habits of greenland halibut in the eastern bering sea and in the northwest atlantic found no die1 patterns in stomach content (yang & livingston 1988; bowering & lilly 1992). for starry ray from the eastern coast of north america, mceachran et al. (1976) found no indication of die1 feeding periodicity; large volumes of prey were found during all periods of day. however, in later studies plots of percentage contributed by major taxa per time period revealed that most euphau sids occurred in the rays collected during the night and early morning (0.00-12.00 hrs). earlier studies of the feeding habits of redfish, greenland halibut and starry ray in west greenland waters (r fig. 10. plot of total length of redfish found in greenland halibut stomachs from the sampling station off west greenland versus predator length. heavy line indicate upper size limit of prey taken. (dots = actual measured total length, circle = calculated total length). found areal variations in mean tfi for these species, but except for redfish no significant effects of sampling season on mean tfi were found (pedersen & riget 1993; pedersen in press). comparisons of the size-frequency distribu tions of redfish found in the greenland halibut stomachs (fig. 8) and in the catches (fig. 5) show that the redfish in the stomachs are smaller than in the catches. this difference is due to a com bination of availability and prey size preference. if prey size preference were the dominating factor for prey selection, redfish prey in the size range 8-12cm should have had a higher frequency of occurrence in the greenland halibut stomachs than actually seen (see fig. 10). therefore, avail ability may overrule the importance of size dependent prey preference and small redfish in fig. 11. combined size frequency distributions of northern shrimp in stomachs of starry ray from the sampling station off west greenland. p ~ ~ ~ ~ w n n n n n n n n n n w ~ w ~ o n w c u d ~ ~ w o n w c u ~ ~ ~ ~ o n ~ carapace length (mm) shrimp trawl catches and stomach contents of redfish, halibut and starry ray 195 size range 6-8 cm may be much more abundant and available for greenland halibut than indi cated from the size-frequency distributions of redfish in the catches. a trial fishery during the greenland shrimp and fish survey in 1993 in the same area as the present study showed that a 20mm mesh size in the cod-end of the shrimp trawl caught 3-8 times as many small redfish (6 10 cm) compared t o the normally used mesh size of 44 mm (beck & pedersen unpubl.). a 20 mm mesh size gave minor effects on the cpues of larger redfish ( > l o cm). comparisons of the size frequency distributions of northern shrimp found in the greenland halibut stomachs (fig. 9) and in the catches (fig. 4) show similarities between the size-frequency distribution in the stomachs and the size-frequency distribution of the shrimp caught in the daytime haul. this indicates that greenland halibut feed on the most abundant shrimp sizes in their habitat. the smallest shrimps (4 mm cl) found in this study from the starry ray stomachs are probably new settled shrimp of age 0 (fig. 11). small shrimps (4 mm cl) were not seen in either the redfish or greenland halibut stomachs from this or earlier studies probably because they occur closer to the bottom and there fore are more available for starry ray. shrimp of age group 0 (3-5mm cl) have been reported from cod stomachs collected from other areas of the northwest atlantic (parsons et al. 1986; lilly & parsons 1991). as in the present study lilly & parsons (1991) found shrimp of age group 0 in the same areas and depths as larger shrimp. the data analysed in this study were obtained from only four trawl hauls performed at 6-hour intervals; therefore, given this weakness no firm conclusions on diel feeding behaviour can be drawn. however, the study indicates that feeding of redfish, greenland halibut and starry ray is taking place throughout the 24-hour cycle with no clear diel feeding rhythms. fixed diel cycles of activity may have high selective value (e.g. by reducing competition between species) and are most clearly seen in tropical fish communities (helfman 1993). in arctic waters, low tem peratures, large annual fluctuations in light, and productivity generally result in lower rates of food consumption, metabolism, stomach evacuation and growth in the fish as compared to fish in tropical and temperate waters. this probably makes diel feeding of less importance and, there fore, less visible. for fish in arctic waters, oppor tunistic feeding and the ability to change rhythms in response to changes in the environment and prey availability may be much more important and favoured. acknowledgemenrs. i wish to thank the crew on m/tr paa miut for help at sea and especially klaus h. nygard who organised the sampling. thanks t o k. l. nielsen and jens jeppesen for assistance in the laboratory. i also thank g . lilly and one anonymous referee for many useful comments provided in reviews of this paper. references anonymous 1994. northwest atlantic fisheries organization. scientific council reports 1993 (redbook). dartmouth, can ada. 234 pp. bowering, w. r. & lilly, g. r . 1992: greenland halibut reinhardtius hippoglossoides off southern labrador and northeastern newfoundland (northwest atlantic) feed pri marily on clpelin (mallofus uillosw). netherlands j. sea res. 29(1-3), 211-222. bromley, p. j. & last, j. m. 1990: feeding in the trawl and the consequences for estimating food consumption in natural fish populations. ices cm 1990/g:35. buch, e. 1990: a monograph on the physical environment of greenland waters. greenland fisheries research institute. 405 pp. campbell, r. c. 1975: sratistics for biologists. cambridge uni versity press. 385 pp. clark, m. r . 1985: the food and feeding of seven fish species from the campbell plateau, new zealand. new zealand j . mar. freshwater res. 19, 33s363. dos santos. j . & jobling, m. 1991: gastric emptying in cod, gadus morhua l . : emptying and retention of indigestible solids. j . fish biol. 38, 187-197. dos santos, j. & jobling, m. 1992: a model to describe gastric evacuation in cod (gadus morhua l.) fed natural prey. ices j . mar. sci. 49, 145-154. eggers, d. m. 1977: factors in interpreting data obtained by diel sampling of fish stomachs. j. fish. brd. can. 34, 2% 294. helfman, g. s. 1993: fish behavior by day, night and twilight. pp. 47%512 in pitcher, t. j. (ed.): the behauior ofreleosr fishes. croom helm, london and sidney. horsted, s. a. & smidt, e. 1956: the deep sea prawn (pandalus borealis kr.) in greenland waters. medd. danmarks fisk. hauundersog. n . s . 1111). 118 pp. horsted, s . a . & smidt. e. 1965: remarks on effect of food animals on cod behavior. international commission for the northwest atlantic fisheries, icnaf special publication no. 6, 435-437. hyslop, e. j. 1980: stomach contents analysis a review of methods and their application. j. fish biol. 27, 411-429. jarre, a,, palomares, m. l., soriano, m. l., sambilay, v. c., jr. & pauly, d. 1991: some new analytical and comparative methods for estimating the food consumption of fish. ices marine science symposia 193, 9%108. longhurst, a. r. 1976: vertical migration. pp. 116-137 in cushing. d. h . and walsh, j. j. (eds.): the ecology of the seas. blackwell. lilly, g . r. & parsons, d. g. 1991: distributional patterns of the northern shrimp (pandalw borealis) in the northwest 196 s. a . pedersen atlantic as inferred from stomach contents of cod (cadus morhua). ices cm 1991/k:41. mceachran, j . d., boesch, d. f. & musick, j . a. 1976: food division within two sympatric species-pairs of skates (pisces: rajidae). mar. biol. 35, 301-317. parsons, d. g.. lilly, g. r. & chaput. g . j. 1986: age and growth of northern shrimp pandalus borealis off north eastern newfoundland and southern labrador. tram. a m . fish. soc. 115. 872-881. penneington, m. 1985: estimating the average food con sumption by fish in the field from stomach contents data. dana 5,81-86. pedersen. s. a. i n press: feeding habits of starry ray (raja radiata) in west greenland waters. ices j . mar. sci. pedersen, s . a. & riget, f. 1993: feeding habits of redfish (sebastes spp.) and greenland halibut (reinhardtius hip poglossoides) in west greenland waters. ices j . mar. sci. 50,445-459. pedersen, s. a. & kanneworff, p. in press: fishes on the west greenland shrimp grounds, 1988-1992. ices j . mar. sci. smidt, e . 1969: the greenland halibut reinhardtius hip pog/ossoides (walb.). biology and exploitation i n greenland waters. medd. danmarks fisk. haounderseg. n . s . 6 ( 4 ) . 1% 148. kobenhavn. smidt, e. 1978: diurnal variation in shrimp catches on the offshore grounds in icnaf divisions 1b and 1c. icnaf selected papers number 4 , 45-46. yang, m. s. & livingston, p. a. 1988: food habits and daily ration of greenland halibut, reinhardtius hippoglossoides, in the eastern bering sea. fish. bull. 86(4). 675-690. wootton, r. j. 1990: ecology of teleost fishes. chapman and hall, london. 404 pp. doi:10.3402/polar.v34.23775 r e s e a r c h / r e v i e w a r t i c l e status and trends in the structure of arctic benthic food webs monika kędra,1,2 charlotte moritz,3,4 emily s. choy,5 carmen david,6 renate degen,6 steven duerksen,7 ingrid ellingsen,8 barbara górska,1 jacqueline m. grebmeier,2 dubrava kirievskaya,9 dick van oevelen,10 kasia piwosz,11 annette samuelsen12 & jan marcin węsławski1 1 institute of oceanology polish academy of sciences, powstańców warszawy 55, pl-81-712 sopot, poland 2 chesapeake biological laboratory, university of maryland center for environmental science, p.o. box 38, solomons, md 20688, usa 3 institut des sciences de la mer, université du québec à rimouski, 310 allée des ursulines, rimouski, quebec g5l 3a1, canada 4 centre de recherches insulaires et observatoire de l’environnement 3278, national center for scientific research, école pratique des hautes études, university of perpignan via domitia, bp1013, 98729 papetoai, moorea, french polynesia 5 department of biological sciences, university of manitoba, winnipeg, manitoba r3t 2n2, canada 6 alfred wegener institute, am handelshafen 12, de-27570 bremerhaven, germany 7 department of biology, dalhousie university, halifax, nova scotia b3h 4r2, canada 8 sintef fisheries and aquaculture brattørkaia 17c, no-7010 trondheim, norway 9 research center, novgorod state university, bolshaya st. petersburgskaya ul., 41, veliky novgorod, 173003, russia 10 royal netherlands institute for sea research, yerseke ecosystem studies, p.o. box 140, nl-4400 ac yerseke, the netherlands 11 national marine fisheries research institute, department of fisheries oceanography and marine ecology, ul. kołłątaja 1, pl-81-332 gdynia, poland 12 nansen environmental and remote sensing center, hjort centre for marine ecosystem dynamics, thormoelensgate 47, no-5006, bergen, norway keywords arctic; food web; climate change; sea-ice retreat; trophic transfer; pelagic�benthic coupling. correspondence monika kędra, institute of oceanology polish academy of sciences, powstańców warszawy 55, pl-81-712 sopot, poland. e-mail: kedra@iopan.gda.pl abstract ongoing climate warming is causing a dramatic loss of sea ice in the arctic ocean, and it is projected that the arctic ocean will become seasonally ice-free by 2040. many studies of local arctic food webs now exist, and with this review paper we aim to synthesize these into a large-scale assessment of the current status of knowledge on the structure of various arctic marine food webs and their response to climate change, and to sea-ice retreat in particular. key drivers of ecosystem change and potential consequences for ecosystem functioning and arctic marine food webs are identified along the sea-ice gradient, with special emphasis on the following regions: seasonally ice-free barents and chukchi seas, loose ice pack zone of the polar front and marginal ice zone, and permanently sea-ice covered high arctic. finally, we identify knowledge gaps in different arctic marine food webs and provide recommendations for future studies. the arctic ocean is experiencing significant warming of approximately three times the global average (steele et al. 2008; serreze et al. 2009; polyakov et al. 2010) and, despite a very pronounced seasonality, recent winter warming far exceeds that occurring in summer (screen & simmonds 2010). one of the characteristic features of the arctic ocean is sea ice, present permanently at high latitudes and seasonally at lower latitudes in winter (fig. 1). the most conspicuous sign of warming is the dramatic loss of sea ice (higgins & cassano 2009; parkinson & comiso 2013): its summer extent has decreased by nearly 50% over the past decade (fig. 1), and the arctic ocean has undergone a regime shift from multi-year ice to largely seasonal and much thinner ice cover (comiso 2012). the arctic ocean may become seasonally ice-free by as early as 2040 (polyakov et al. 2010). reductions in sea-ice cover are being further amplified by increased heat fluxes into the arctic ocean through the bering (woodgate et al. 2006; woodgate et al. 2010; woodgate et al. 2012) and fram straits (piechura & walczowski 2009). this enhanced ocean temperature further delays the growth of sea ice in the fall (steele et al. 2008). in terms of ecosystem functioning, these patterns indicate a shift towards an earlier spring transition between sea-ice-covered and polar research 2015. # 2015 m. kędra et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 sea-ice-free conditions (grebmeier, overland et al. 2006; steele et al. 2008). therefore, in the arctic, climate change is not only affecting the physical structures such as sea ice, but is also responsible for multiple ecological changes on ecosystem functioning, including food-web structure, stability and efficiency, especially by affecting components at the base of the food web. the two main sources of primary production in arctic ecosystems are sea-ice algae and phytoplankton (søreide et al. 2006). the growth of both ice algae and phytoplankton takes place within a one to four month period during spring and summer (søreide et al. 2006; renaud, carroll et al. 2008; iken et al. 2010). the productive season starts at the end of the polar night with sunlight triggering the bloom of sea-ice algae. even though they constitute only a small-to-moderate portion (b20%) of total annual primary production (hegseth 1998; gradinger 2009), ice algae contribute to arctic benthic food webs during springtime on shallow continental shelves with seasonal ice cover because they occur early and sink fast following sea-ice retreat (hobson et al. 1995; tamelander et al. 2006). this ice algal contribution is proportionally more important in areas where sea-ice cover lasts later in the year (gosselin et al. 1997) but is expected to decrease with current sea-ice retreat (leu et al. 2011). a phytoplankton spring bloom follows the ice algae bloom as the sea-ice cover melts (leu et al. 2011). in the summer, limited nutrients support a low phytoplankton biomass (wassmann & reigstad 2011), with episodic bloom conditions facilitated by occasional nutrient availability (grebmeier, cooper et al. 2006). these phytoplankton blooms, although responsible for the bulk of annual production, are usually restricted to open waters (but see arrigo et al. 2012; mundy et al. 2014). boetius et al. (2013) also showed that sinking ice algae aggregates constitute an important food input to benthos in the arctic basins. in addition to phytoplankton and ice algal production, microbial oceanic phototrophs can contribute up to 50% of total inorganic carbon assimilation and play a leading role in nutrient cycling (falkowski et al. 1998). bacterial primary production ratios have been estimated to reach more than 240% above 818n (rich et al. 1997) compared to 1�143% (3296%) in the barents sea (sturluson et al. 2008). the bacterial contribution to respiration in the water column may be substantial: 3�60% in the chukchi sea and canada basin, and 25% on average in the arctic (kirchman et al. 2009). moreover, bacterial activity on sinking particles, an important habitat that harbours distinct communities of arctic bacteria (hansell & ducklow 2003; hodges et al. 2005), directly affects the quantity and quality of the organic matter that reaches the seafloor. in coastal areas and interior shelves, coastal erosion, river and glacial discharge can become important sources of terrestrial organic matter that can also be further utilized in benthic food webs (dunton et al. 2006; dunton et al. 2012; kędra et al. 2012; kuliński et al. 2014). the quality and quantity of primary production, including ice algae and phytoplankton, reaching the seafloor have a strong impact on benthic communities (pearson & rosenberg 1978), which further cascades through the whole food web, especially in the highly seasonal arctic marine ecosystems. shallow arctic shelves in particular are characterized by tight pelagic�benthic coupling due to low grazing in the water column during the bloom (grebmeier et al. 1988; grebmeier & mcroy 1989; renaud, carroll et al. 2008; tamelander et al. 2008). this results in large export of organic matter, produced in the surface layers and descending to the seafloor and benthos (grebmeier, cooper et al. 2006), especially in spring, when production is far greater than zooplankton consumption (tamelander et al. 2006). for example, almost 70% of the organic carbon produced in the water column during spring in the pacific arctic region reaches the seafloor (walsh et al. 1989), supporting high biomass, abundance and diversity of benthic organisms (grebmeier & mcroy 1989; grebmeier, cooper et al. 2006; iken et al. 2010; bluhm, gradinger et al. 2011), which are important prey items for higher trophic level animals foraging on the seafloor, including diving sea ducks (merginae), bearded seals (erignathus barbatus), walrus (odobenus rosmarus) and grey whales (eschrichtius robustus) (lovvorn et al. 2003; grebmeier, cooper et al. 2006; grebmeier & barry 2007; grebmeier 2012). this contrasts with the summer period, when grazing of phytoplankton by zooplankton may reach up to 97% of daily water column primary production in more pelagic-oriented areas like the barents sea (tamelander et al. 2006), thus limiting carbon export to the benthos. during summer, reworked organic matter consisting of zooplankton faecal pellets and carcasses, moults and bacteria, as well as phytodetritus, primarily fuels benthic food webs. many shallow shelf arctic systems, especially in the pacific arctic, have a high efficiency of energy transfer from the water column to the benthos (ambrose & renaud 1995). macroand megafauna appear to play a prominent role in carbon recycling (up to 30% efficiency for arctic benthos; clough et al. 2005; renaud et al. 2007), but studies focusing on partitioning of carbon recycling for bacterial, meiofaunal, macrofauna and megafaunal components are rare (piepenburg et al. 1995). trophic transfer efficiency describes the efficiency with which energy is transferred from one trophic level to the next, in particular the relative percentage of primary status and trends in the structure of arctic benthic food webs m. kędra et al. 2 (page number not for citation purpose) citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 production that reaches top predators (kozlovsky 1968). species interactions, of which many are sea-ice related in arctic ecosystems (fortier et al. 2002; gradinger & bluhm 2004; søreide et al. 2006; gradinger 2009), control energy and organic matter flow which determine ecological efficiencies and can limit productivity and patterns of species dominance and food-web stability (mccann 2000). in the changing arctic ocean, species shifts and local extinctions and invasions may occur, leading to new interactions between species that have not co-evolved (hobbs et al. 2006). new or missing links in established food webs may lead to large energy inefficiencies, changes in energy pathways that currently support key top predators, and destabilization of food-web dynamics (vander zanden et al. 1999; pauly et al. 2002). however, this process is also dependent on the level of trophic and functional redundancy in a system (layman et al. 2007). understanding how arctic food webs will become fig. 1 map of the arctic ocean showing the minimum sea-ice extent september 2012 and the median sea-ice extent february 1981�2010 (blue line). locations of published food-web studies and the case study areas of this review are marked with yellow (seasonally ice-free areas), blue (marginal ice zone [miz]) and grey (permanently ice-covered high arctic) stars. red circles indicate areas that require more investigation. bathymetry after amante & eakins (2009); sea-ice data from fetterer et al. (2002). m. kędra et al. status and trends in the structure of arctic benthic food webs citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 structured in the future will therefore entail disentangling the factors with most impact on interspecific interactions. the aim of this paper is to present the current status of knowledge of the structure of various arctic marine benthic food webs and their observed responses to ongoing climate change, in particular to sea-ice retreat. potential changes to food-web trophic transfer efficiency are also discussed. to date, most focused studies of arctic food webs are limited in space, time or taxonomic level (e.g., iken et al. 2005; aydin & mueter 2007; bergmann et al. 2009; megrey & aydin 2009; iken et al. 2010; feder et al. 2011; dunton et al. 2012; whitehouse et al. 2014), and largescale syntheses across the arctic are generally missing. only a few pan-arctic reviews have been published (carmack & wassmann 2006; piepenburg et al. 2011; wassmann et al. 2011), and none has focused on species interactions and trophic pathways of food webs nor on food-web structure and with trophic transfer efficiency. to complement existing studies, this review will focus on the key drivers of ecosystem changes in the arctic, including sea-ice decline, temperature rise and changes in stratification and the consequences for important ecosystem functions that are susceptible to change, including nutrient regeneration, primary and secondary production, pelagic�benthic coupling, structure of food webs and consequences for top predators. in particular, we aim to: (1) identify key drivers of ecosystem change and potential consequences for ecosystem functioning; (2) present different scenarios and trends in arctic marine food webs by analysing regional ecosystem case studies located along a sea-ice gradient: the seasonally ice-free barents sea and chukchi sea, the loose ice pack polar front (pf) and the marginal ice zone (miz) and the permanent ice-covered high arctic; and (3) identify knowledge gaps in arctic marine food webs, and suggest possible methods to fill these gaps and provide recommendations for future studies. primary and secondary drivers of ecosystem change: potential consequences key drivers of ecosystem change the primary driver of the observed ecosystem change in high latitudes is ongoing climate change, and warming in particular (symon et al. 2005). increasing air temperature is the main cause of sea-ice decline, along with the secondary drivers of arctic ecosystem change, such as increase in sea-water temperature and altered stratification (symon et al. 2005; stocker et al. 2013). sea ice is a major regulating component in controlling pelagic and benthic production through modulating water column stratification and light fields (bluhm & gradinger 2008; gradinger 2009) because it controls the exchange of heat between the atmosphere and ocean and, together with snow cover, limits the penetration of light into the water column. also, in the arctic ocean, the thaw�freeze cycle of sea ice and large freshwater riverine inputs result in pronounced haline stratification within the surface layer (carmack & wassmann 2006). shortly after the phytoplankton spring bloom, the polar mixed layer becomes and remains nitrogen-depleted because of strong vertical stratification, which prevents replenishment during the summer season (tremblay et al. 2008). analysis of model data shows that when less sea ice is produced and freshwater load is increasing in the arctic ocean, the water column stratification becomes stronger, which decreases winter mixing (slagstad et al. 2011), subsequently affecting nutrient distribution in the water column (li et al. 2009; codispoti et al. 2013; matrai et al. 2013). in general, patterns of nutrients availability in the euphotic zone are a function of the total transport at the barents sea opening and fram strait, through davis strait in the canadian archipelago and bering strait in the pacific arctic region, along with nutrient input from rivers, upwelling, stratification patterns and local mixing of deep water (codispoti et al. 2013). both major sources of nutrients in the arctic ocean, oceanic inputs associated with waters of pacific and atlantic origin, and riverine nutrient fluxes, are likely to change with accelerating climate change (peterson et al. 2002; mcclelland et al. 2006; peterson et al. 2006; shiklomanov & lammers 2009). changes in riverine freshwater runoff will likely be associated with changes in the quality and quantity of the nutrient supply, and while the loads of silicate, phosphate and dissolved and particulate organic matter are expected to increase in the future, trend in riverine nitrogen loads remain largely unknown (frey et al. 2007; raymond et al. 2007; frey & mcclelland 2009). differences between nutrient transport and availability over the shelf areas and central arctic may increase in the future: the already nutrient-depleted central arctic basin will likely become more oligotrophic, while shelf areas will be further enriched by increased transport of atlantic and pacific water masses and runoff. biogeochemical processes and changes in adjacent basins as well as circulation changes may affect the future productivity of the arctic ocean. primary production and its consumers alterations of the seasonal cycle of primary productivity at the base of the food web is one of the most important consequences of rising temperature, sea-ice retreat and status and trends in the structure of arctic benthic food webs m. kędra et al. 4 (page number not for citation purpose) citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 changes in nutrient patterns. in general, ice algae and pelagic phytoplankton production occur sequentially during the year, with the abundance of ice algae relative to pelagic phytoplankton increasing northward coincident with greater sea-ice cover (leu et al. 2011; wassmann et al. 2011; rubao et al. 2013). although light availability and nutrients are often the prime limiting factors for primary production (gradinger 2009; leu et al. 2011), the timing of pelagic phytoplankton blooms is likely controlled by sea-ice retreat, whereas the timing of ice algae blooms is influenced by snow and sea-ice melt and starts earlier than open-water blooms. in many arctic marginal seas, the timing of sea-ice retreat may have a strong impact on the timing of phytoplankton production, but little or no impact on the timing of ice algae peaks. changes in the timing of maximum phytoplankton production influence the variability in time-lags between ice algal and phytoplankton production peak production (from 45 to 90 days; ji et al. 2013). the timing of the seaice algal bloom is an important driver of spring secondary production as earlier ice algae bloom will export larger amounts of primary production to seafloor communities (gradinger 1995), especially when water column grazing is low, strengthening pelagic�benthic coupling processes. changes in timing of the pulses of ice algae and phytoplankton primary production and in the associated gap period between them will influence zooplankton grazer abundances and activities (søreide et al. 2010; varpe 2012). although the timing of primary production varies greatly over time and space in different regions, systematic shifts in the timing of production and export processes have the potential to increase the frequency of mismatch between marine grazers and their food, which in turn can subsequently alter the organic matter flux to the seafloor and/or the transfer to the higher trophic levels (rubao et al. 2013). because arctic zooplankton reproduction is largely determined by the food quality of autotrophs (müllernavarra 2008), production of lipids in sea-ice diatoms early in the season is extremely important (falk-petersen et al. 2009; søreide et al. 2010). these high-energy lipid compounds are rapidly transferred through the arctic marine food chains. changes in the initiation and duration of the growth season, and therefore in the timing, quality and quantity of sea-ice blooms, will directly affect, among others, calanoid copepods (ji et al. 2012), which are critical to energy transfer between lower and higher trophic levels. diatom lipids are accumulated in large amounts by calanus species and ice amphipods, and further transferred to pelagic carnivorous zooplankton and pelagic fish stocks (scott et al. 1999; scott et al. 2001; auel et al. 2002). lipid levels increase from 10�20% in phytoplankton to 50�70% in herbivorous zooplankton and ice fauna that then become available as nutritious prey items for upper trophic level consumers (daase et al. 2014). dominant arctic zooplankton taxa, like calanus glacialis, switch from a diet of ice algae in spring towards phytoplankton in late summer, while others, like the sympagic amphipod apherusa glacialis, feed mainly on ice algae during early spring (falk-petersen et al. 1999; scott et al. 1999; falk-petersen et al. 2006). ice-associated amphipods onisimus spp. switch from ice algae in spring to an omnivorous diet by the end of the productive season (werner & auel 2005). the young ice amphipod gammarus wilkitzkii feeds on ice algae, while their adults have a carnivorous diet, feeding preferentially on calanoid copepods (scott et al. 2001; werner et al. 2002). although most benthic species do not feed directly on algal cells, changes in the timing and quality of bloom sedimentation (the latter additionally influenced by microbial processing) may impact those species’ composition and abundances (ambrose & renaud 1997). changes in the availability or abundance of ice algae or dependent zooplankton communities may cause cascading impacts on higher trophic level populations. microbial processes earlier sea-ice melt and increased stratification of the water column will promote picophytoplankton occurrence. because of their short generation times, microorganisms respond quickly to environmental changes and are the first to react to global changes, affecting key ecosystem functions at the base of food webs (sarmento et al. 2010). significant changes in microbial communities and diversity have already been observed after a sharp decline of sea-ice cover in september 2007 (between 2002 and 2010; comeau et al. 2011). increased carbon supply from pelagic productivity and riverine discharge coupled with increased bottom water temperature could result in higher bacterial activity and rates of bacterial cycling of carbon (kritzberg et al. 2010; vaquer-sunyer et al. 2010). the decreased quality and quantity of sinking particles (wassmann & reigstad 2011) and usable carbon (renaud, morata et al. 2008) being exported to the seafloor would decrease the efficiency of food webs. picophytoplankton is believed to be relatively inaccessible as a prey for mesozooplankton (li et al. 2009); however some studies suggest that protozoans may constitute a larger percentage of copepod diets (campbell et al. 2009), even up to 80�90%, during summertime, when abundances, biomass and production are dominated by picoand nanophytoplankton (piwosz et al. 2009; de laender et al. 2010; piwosz et al. 2015) and when abundances of m. kędra et al. status and trends in the structure of arctic benthic food webs citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 microzooplankton are high (kubiszyn et al. 2014). in herbivore-limited systems, copepod production is therefore closely linked with protozoan production and constitutes a direct link between the microbial loop and higher trophic levels (campbell et al. 2009; sherr et al. 2009; de laender et al. 2010; nelson et al. 2014). still, it is likely that arctic food webs will lengthen at their base with the increase in numbers of trophic transfers within the microbial food webs or the number of grazers in the water column, decreasing the amount of carbon available for the higher trophic levels in the original food chain. our knowledge of the possible impact of viruses and parasitic protists in terms of their capacity to terminate algal blooms in the arctic is limited (nelson et al. 2014). viral infection has been shown to control blooms of the coccolithophore emiliania huxleyi in the northern atlantic (wilson et al. 2002), while parasitic protists in the order syndiniales have been coupled with collapses of blooms of dinoflagellate species in the mediterranean sea (chambouvet et al. 2008). increased impact of algal viruses and parasites would decrease the amount of food available for pelagic and benthic grazers. how these processes affect current blooms in the arctic ocean remains largely unknown, but both viruses and parasitic syndiniales have been reported from sea ice (wells & deming 2006; bachy et al. 2011; collins & deming 2011; comeau et al. 2013; piwosz et al. 2013) and the water column (howardjones et al. 2002; lovejoy et al. 2006; bachy et al. 2011; comeau et al. 2011; payet & suttle 2013). pelagic�benthic coupling the initiation of sea-ice retreat is important for the timing, quality and amount of primary production (springer et al. 1996; hunt & stabeno 2002), and changes in the timing of both ice algae and phytoplankton primary production may cause changes in food webs by influencing the standing stock of zooplankton, which will in turn affect the direct, ungrazed deposition of phytoplankton (cooper et al. 2002) and subsequently benthic species (overland & stabeno 2004; grebmeier, cooper et al. 2006; grebmeier, overland et al. 2006; nelson et al. 2009; grebmeier 2012). in areas with reduced summer sea ice, pelagic grazing pressure will be higher (lalande et al. 2007), perhaps altering sedimentation of organic matter, resulting in more pelagic-oriented systems. with increased primary production (arrigo & van dijken 2011; arrigo et al. 2014; palmer et al. 2014), pelagic food webs could become more productive and intercept more organic matter before it reaches the seafloor (renaud, carroll et al. 2008); however, nutrient limitation may halt this process. increased grazing would reduce the export flux of carbon to the seafloor, weakening pelagic� benthic coupling processes. studies in the bering sea found that with sea-ice cover the spring blooms were characterized by a higher proportion of diatoms, less recycling and greater export and, therefore, stronger pelagic�benthic coupling (moran et al. 2012). in the case of open-water conditions, blooms were characterized by a higher proportion of dinoflagellates, greater carbon cycling in the water column and lower export to the seafloor, and consequently reduced pelagic�benthic coupling (moran et al. 2012). upper trophic levels changes in primary and secondary production affect upper trophic levels and are predicted to have increasing impact with climate warming (wassmann 2006; daufresne et al. 2009; moore et al. 2014). arctic marine top predators will have to face extreme changes in their habitat and forage base, including density and distributional shifts of their prey, as well as potential losses of some of their favoured lipid-rich prey species (kovacs & lydersen 2008; kovacs et al. 2011). upper trophic levels usually respond in a non-linear fashion to changes in ecosystem structure and usually the response depends on their exact position in the food web (moore et al. 2014). although the resilience of arctic top predators is largely dependent on an individual’s adaptive capacity, in general their resilience capacity depends largely on the region, the intensity and range of ice cover change and species characteristics (e.g., ice-obligate species are more vulnerable than ice-associated or seasonally migrant ones [moore & huntington 2008]). sea-ice associated and seaice obligate species such as walruses and bearded seals that use sea ice as a platform for breeding, resting and foraging will be most affected by changes in sea-ice cover (laidre et al. 2008; moore & huntington 2008; table 1). reductions in prey quality have been observed to have ecosystem-wide effects, such as population crashes of steller sea lions (eumetopias jubatus) in the gulf of alaska (rosen & trites 2000) and breeding failures of seabirds in the north sea (wanless et al. 2005). a decline in spawning and foraging areas will affect both predators and their prey. for instance, polar cod (boreogadus saida) abundance might be significantly reduced, with tremendous consequences to the entire system as this species is believed to account for up to 75% of energy transfer between zooplankton and vertebrate predators (darnis et al. 2012). in addition to changes in resource availability, top predators will likely face increased complexity within food webs that tend to dissipate energy flow (węsławski et al. 2009). this will likely be followed by increased status and trends in the structure of arctic benthic food webs m. kędra et al. 6 (page number not for citation purpose) citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 competition from temperate species that are expanding northward, e.g., atlantic cod (gadus morhua), haddock (melanogrammus aeglefinus) (renaud et al. 2012) and atlantic mackerel (scomber scombrus) (berge et al. 2015), and increased predation from species formerly unable to access them in areas of extensive sea-ice cover, such as killer whales (orcinus orca) (higdon & ferguson 2009), gannets following northward move of herring and mackerel (symon et al. 2005), and fish-eating whales that are getting more abundant in the pacific arctic region (grebmeier 2012; moore et al. 2014). also, an increase in temperate and sub-arctic fish migration is predicted to lead to a decrease in prey quality, since they are less lipidrich than arctic species (symon et al. 2005; hop & gjøsæter 2013). additionally, increased risks of disease and contaminants may also become an issue (kovacs & lydersen 2008). changes in species distribution ranges mediated by temperature temperature has a direct impact on metabolic and physiological processes as well as on the behaviour of individual organisms (duarte 2007; o’connor et al. 2007). it may influence growth, survival, reproduction, phenology and recruitment success of particular species (lewis 1996; walther et al. 2002; lewis 2005; herbert et al. 2007). therefore, spatial distributions of organisms will likely change because of differential survival and recruitment of pelagic larval stages with varying water temperatures (sirenko & kolutin 1992; blanchard et al. 2010; grebmeier 2012). changes in phenology can lead to a decoupling of the dynamics between predator and prey that will further alter current trophic relations and communities. some species time their reproductive efforts to match the spring algal bloom (falk-petersen et al. 2009), e.g., females of the copepod calanus glacialis utilize the spring pulse of ice algae to initiate reproduction, allowing their young to feed on the phytoplankton bloom that occurs after the breakup (søreide et al. 2010). along with temperature rise and sea-ice reduction, an increase in small-sized phytoplankton cells is predicted (li et al. 2009) as well as a decrease in individual body size coupled with an increase in proportion of juveniles (daufresne et al. 2009). at the population level, a shift of species may be observed, e.g., large, lipid-rich zooplankton species, such as c. glacialis and c. hyperboreus are being replaced by the smaller boreal and lipid-poorer species c. finmarchicus (falk-petersen et al. 2006). sea-water temperature rise and warmer atlantic and pacific waters advected northward also represent a threat to arctic biodiversity and may further change trophict a b le 1 c ir c u m p o la r a rc ti c to p p re d a to rs , th e ir p ri n c ip a l fo o d so u rc e s a n d e st im a te d p o p u la ti o n si ze s. s p e c ie s h a b it a t p ri n c ip a l fo o d so u rc e p o p u la ti o n si ze r e fe re n c e f u lm a r (f u lm a ru s g la c ia lis ) p e la g ic , su rf a c e c e p h a lo p o d s, e p ip e la g ic fi sh , p te ro p o d s, fl o a ti n g c a rr io n 1 5 0 0 0 0 0 0 �3 0 0 0 0 0 0 0 b ir d l if e in te rn a ti o n a l 2 0 1 2 b s p e c ta c le d e id e r (s o m a te ri a fi sc h e ri ) c o a st a l, p e la g o b e n th ic b e n th o s, c ru st a c e a n s, m o llu sc s 3 3 0 0 0 0 �3 9 0 0 0 0 b ir d l if e in te rn a ti o n a l 2 0 1 2 c l it tl e a u k (a lle a lle ) c o a st a l, p e la g ic p e la g ic c ru st a c e a n s, c o p e p o d s 1 6 0 0 0 0 0 0 �3 6 0 0 0 0 0 0 b ir d l if e in te rn a ti o n a l 2 0 1 2 a r in g e d se a l (p h o c a h is p id a ) c o a st a l, p e la g o b e n th ic , 0 �1 0 0 m p o la r c o d , d e m e rs a l fi sh , la rg e c ru st a c e a n s 2 5 0 0 0 0 0 m iy a za k i 2 0 0 2 b e a rd e d se a l (e ri g n a th u s b a rb a tu s) c o a st a l, b e n th ic , 0 �1 0 0 m d e m e rs a l fi sh , c ra b s, sh ri m p s, u rc h in s u n k n o w n k o v a c s 2 0 0 2 g re e n la n d se a l (p h o c a g ro e n la n d ic a ) p e la g ic , 0 �1 0 0 m p e la g ic fi sh 8 0 0 0 0 0 0 k o v a c s 2 0 0 8 w a lr u s (o d o b e n u s ro sm a ru s) b e n th ic , 0 �5 0 m l a rg e b iv a lv e s, g a st ro p o d s, sh ri m p s u n k n o w n l o w ry e t a l. 2 0 0 8 m in k e w h a le (b a la e n o p te ra a c u to ro st ra ta ) p e la g ic , 0 �2 0 0 m l a rg e p e la g ic c ru st a c e a n s, p te ro p o d s, p e la g ic fi sh 1 8 2 0 0 0 r e ill y e t a l. 2 0 0 8 a b o w h e a d (b a la e n a m y st ic e tu s) p e la g ic p e la g ic c ru st a c e a n s, c o p e p o d s � 1 0 0 0 0 r e ill y e t a l. 2 0 1 2 e a st e rn n o rt h p a c if ic g re y w h a le (e sc h ri c h ti u s ro b u st u s) p e la g ic b e n th o s, a m p h ip o d s 1 5 0 0 0 �2 2 0 0 0 r e ill y e t a l. 2 0 0 8 b b e lu g a w h a le (d e lp h in a p te ru s le u c a s) c o a st a l, p e la g ic , e st u a ry c o a st a l a n d p e la g ic fi sh , c ru st a c e a n s, c e p h a lo p o d s � 1 5 0 0 0 0 je ff e rs o n e t a l. 2 0 1 2 m. kędra et al. status and trends in the structure of arctic benthic food webs citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 relationships and food-web structure. these changes will facilitate open-water adapted species and boreal species to expand northward and ice-adapted species to retract in range (e.g., sirenko & gagaev 2007; hollowed et al. 2013), which may lead to local extinctions, especially in the case of sea-ice dependent fauna (clarke & harris 2003). changes have already been observed, including a northward distributional shift of fish and invertebrates in the bering sea (mueter & litzow 2008) and in the north atlantic (wienerroither et al. 2011), penetration of pacific clams into the chukchi sea (sirenko & gagaev 2007), reoccurrence of atlantic mussels in svalbard (berge et al. 2005), and pacific zooplankton northward movement into the beaufort sea (nelson et al. 2009). also, an increase in year-round resident species may occur, e.g., grey whales that usually migrate south may stay in the bering and chukchi seas longer because of expanded open-water feeding areas and warmer water temperature (moore & huntington 2008). sea-ice gradient: scenarios and trends since sea-ice retreat is probably the most critical of expected consequences of climate warming for the arctic marine ecosystems, in this review three regional ecosystem case studies are used to conceptualize possible changes in food-web structure and efficiency along a sea-ice gradient: the seasonally ice-free barents sea and chukchi sea, the loose ice pack pf and miz and the permanently ice-covered high arctic (table 2, fig. 2a, b). in general, the described scenarios refer to current or possible future conditions on the shelves. the barents and chukchi seas were chosen as two case studies as the food webs and associated trophic relations there are relatively well-studied (e.g., iken et al. 2010; feder et al. 2011; renaud et al. 2011; dunton et al. 2012; grebmeier 2012; kędra et al. 2012; nelson et al. 2014; table 2, fig. 2). pf and miz are highly productive zones, which are likely to change their locations, extents and features as the ice edge retreats from the coast and continental shelves (fig. 2). arctic deep-sea regions represent a large part of the arctic ocean susceptible to change due to fast sea-ice retreat, yet studies of deep benthic food webs are scarce (bergmann et al. 2009; iken et al. 2010; van oevelen et al. 2011; table 2). in all three case studies, the scale and the extent of response to climate change and sea-ice retreat remain largely unknown. arctic shelf: seasonally ice-free*barents and chukchi seas many arctic shelf systems are characterized by high benthic biomass and production especially in areas of inflow of atlantic or pacific nutrient-rich water masses, and along the pf (carmack & wassmann 2006; grebmeier, cooper et al. 2006; renaud, morata et al. 2008; fig. 2a). on the south-eastern chukchi sea shelf, primary production can exceed 430 g c m �2 y �1 (springer et al. 1996; sakshaug 2004; lee et al. 2007); the barents sea has an estimated overall average annual primary productivity of about 100 g c m �2 y �1 and up to 300 g c m �2 y �1 in shallow banks (sakshaug et al. 2009). typically, about 44�67% of primary production in the barents sea reaches the seafloor (wassmann, reigstad et al. 2006; wassmann, slagstad et al. 2006) while it is up to 70% in the chukchi sea (walsh et al. 1989). unlike the chukchi sea, the barents sea supports immense fisheries and a high density of cetaceans. pelagic foraging piscivores and nesting seabirds are twice as abundant in the barents sea than in the chukchi sea (hunt et al. 2013). in the barents sea, seasonally resident cetaceans are four to five times more abundant than in the chukchi sea. on the other hand, the density of pinnipeds and benthic-foraging whale species in the chukchi is twice that of the barents sea, indicative of the chukchi sea being more of a benthic-driven system than the barents sea (hunt et al. 2013). indeed, chukchi soft sediment infaunal and epifaunal communities are among the most productive in the world, reaching up to 50�100 g c m�2 or up to ca. 4 kg wet wt m �2 (grebmeier et al. 1988; grebmeier, overland et al. 2006; feder et al. 2007), while in the most productive areas of shallow banks in the barents sea the benthic fauna reaches up to 30 g c m �2 or 1.5 kg wet wt m �2 (kędra et al. 2013). table 2 number of food-web studies undertaken in the arctic by area. data were collected using the search terms ‘‘arctic’’ and ‘‘marine’’ and ‘‘food web’’ on the web of science. studies that examined the relationship between two or more trophic levels were retained. reviews and modelling with no in situ studies were excluded. area number of studies barents sea 18 bering sea 17 beaufort sea 44 canadian arctic 69 central arctic ocean 7 chukchi sea 16 greenland sea 23 labrador sea 61 laptev sea 1 svalbard 45 white sea 1 yermak plateau 2 total 304 status and trends in the structure of arctic benthic food webs m. kędra et al. 8 (page number not for citation purpose) citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 the ice edge is retreating northwards and, in the near future, ice-free summers and seasonal ice cover in winter may become typical for the shelf seas (fig. 2b). increases in primary production and phytoplankton biomass are predicted, as well as have been measured, as a consequence of sea-ice retreat and temperature rise (gradinger 1995; arrigo et al. 2008; arrigo & van dijken 2011; wassmann & reigstad 2011). moreover, increased advection of atlantic and pacific waters into the arctic basin in the last decade (walczowski & piechura 2006; woodgate et al. 2006; piechura & walczowski 2009; woodgate et al. 2010; walczowski et al. 2012) resulted in a 30% local increase of total primary productivity due to a greater proportion of smaller boreal planktonic species (leu et al. 2011). apart from quantitative changes in primary production, the quality and seasonality of primary production are expected to change because of the earlier onset of ice melt. various stages of the reproductive cycle or increased activity of some arctic benthic animals are timed to coincide with peak periods of organic matter deposition (blake 1993; renaud et al. 2007), so any change in seasonality, quantity or quality of food input may create a mismatch with faunal reproductive cycles (renaud, carroll et al. 2008). a shift from a benthicoriented ecosystem with relatively low zooplankton stocks and strong pelagic�benthic coupling to a system dominated by pelagic food webs has already occurred in the northern bering sea in 1970s and 1980s (overland & stabeno 2004; grebmeier, overland et al. 2006) and benthic productivity has been decreasing over the past two decades in the northern bering and southern chukchi seas (moore et al. 2003; grebmeier, overland et al. 2006; grebmeier 2012). loose ice pack*miz and pf a significant feature of the recent (2007�2012) decrease in ice extent has been the retreat of the ice edge away from the coast and continental shelves. one of the most obvious impacts has been the northward expansion and widening of the miz, a dynamic and biologically active band of sea-ice cover adjacent to the open ocean (strong & rigor 2013). miz width is a fundamental feature for polar ecosystem functioning and climate dynamics (wadhams 2000). it is an interfacial region that forms at the boundary of open and frozen ocean and fig. 2 (a) current and (b) predicted food-web scenarios for the arctic shelf, marginal ice zone (miz) and polar front (pf), and the high arctic with permanent ice cover. the size of the picture frame for (b) reflects the predicted changes of relative contribution of each area. m. kędra et al. status and trends in the structure of arctic benthic food webs citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 protects the stable morphology of the inner ice from wave penetration (squire 2007). in the miz, interactions between sea-ice and the open sea result in modification of the properties of the ice compared to areas deeper within the pack (weeks 2010). significant forcing that impacts the sea ice in the miz results in varying surface roughness (gupta et al. 2014), which affects prevalent physical and biological processes in the miz, such as wave dynamics (wadhams et al. 1988; squire et al. 1995), heat (perovich et al. 1989), salt fluxes (mcphee et al. 2008) and floe size distribution (lu et al. 2008). it can also create potential habitats for organisms inhabiting the ocean�ice system (e.g., arctic cod [fortier et al. 2006]). properties of the miz relative to neighbouring ice pack can markedly affect the carbon cycle and behaviour of microorganisms and top-level predators (dunbar & leventer 1987; arrigo et al. 2012). the miz has been a long-standing feature in many arctic shelf seas, like in the bering, chukchi and barents seas, but is a relatively new phenomenon in higher latitude regions such as the deep beaufort sea and canada basin (shimada et al. 2006). the miz is advancing poleward into regions where sea ice has become increasingly younger and thinner at the beginning of the annual melt (strong & rigor 2013). at the time of minimum sea-ice extent in september, the sea-ice edge is located over the deep arctic ocean, exposing large areas of previously permanently icecovered waters, and miz-type conditions are becoming more prevalent in the high arctic with the advancement of climate change. loss of sea ice will likely change the amount and characteristics of primary production in the miz (bluhm & gradinger 2008; fig. 2b). increased summer sea-ice melt will increase the overall extent of the miz over the shelves and lead to increased primary productivity (anderson & kaltin 2001). however, export fluxes largely depend on the coupling processes in the water column, including grazing, and therefore may not increase with warmer temperatures, especially in deep areas (forest et al. 2010). even if primary production increases, the fate of export fluxes will be different on arctic shelves and over the deep arctic ocean (lalande et al. 2014). it is likely that particulate organic carbon export will remain low above the central basins unless additional nutrients are supplied to surface waters (codispoti et al. 2013; lalande et al. 2014). decreased export of diatoms, and dominance of coccolithophores were observed in fram strait during the warm period of 2005�07 (bauerfeind et al. 2009; lalande et al. 2013). warmer water temperature also resulted in lower export fluxes of smaller zooplankton faecal pellets due to a shift in zooplankton community composition towards small-sized zooplankton species or a shift in phytoplankton composition that affected grazing and faecal pellet production (lalande et al. 2013). however, over the shelves, increased primary productivity will likely supply more food to pelagic and benthic consumers, while the low-productivity zone of the multi-year sea ice would shrink (bluhm & gradinger 2008). sea-ice retreat off the shelves may result in upwelling of nutrients or planktonic prey from the basins onto the shelves (carmack et al. 2004). based on the inorganic carbon availability, anderson & kaltin (2001) proposed a possible increase of up to 50 g c m �2 integrated over the upper 100 m of the water column across the eurasian basin, mainly as a result of ice loss. nevertheless, it is the availability of nutrients, mainly nitrogen and phosphorous, that ultimately determines the total amount of primary productivity possible in any given ocean (codispoti et al. 2013). with reduced ice cover, ice-edge algal blooms will be displaced progressively northwards. although benthic communities will still receive high-quality food in the short term, if the sea-ice edge retreats past the shelf break, shelf communities will no longer benefit from this early season food source (renaud, carroll et al. 2008) which would result in increased food input to slope and deep-sea communities (carmack & chapman 2003). since it is likely that at least a part of deep-sea fauna originates from shelf species and arctic shelf and deepsea taxa largely overlap (bluhm, ambrose et al. 2011), some shelf species would be able to dwell in the deep sea. if shelf species were unable to leave the slopes or survive in slope or deep-sea habitats, many arctic shelf�benthos taxa could become locally extinct (renaud, carroll et al. 2008). changes in under-ice community structure were noticed in the eurasian basin in geographically close sampling locations collected within short time intervals. habitat partitioning between sympagic and pelagic species can be abrupt, creating small-scale patterns in the surface layer community according to sea-ice habitat conditions. the difference in ice coverage was accurately mirrored by a conspicuous dominance of the iceassociated amphipod apherusa glacialis in ice-covered waters, versus a dominance of the pelagic amphipod themisto libellula in the surface community of ice-free waters (koszteyn et al. 1995; hop & pavlova 2008; david et al. 2015). fronts are regions characterized by narrow bands of horizontal gradients in temperature, salinity, density and biological properties that separate broader areas of different vertical structure (mann & lazier 1996; belkin et al. 2003). in the barents sea, the pf separates warmer, more saline atlantic waters in the south from colder, less saline arctic water in the north (loeng 1991). fronts can status and trends in the structure of arctic benthic food webs m. kędra et al. 10 (page number not for citation purpose) citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 play a role in setting surface layer properties by restratifying the surface layer (timmermans & winsor 2013) and thereby enhancing primary production. fronts are known to support elevated biomasses of phytoplankton (iverson et al. 1979), planktonic organisms (basedow et al. 2014) and hyper-benthic communities (dewicke et al. 2002) as well as bird and mammal aggregations (bluhm et al. 2007). however, a recent study of the pf in the barents sea found no stimulatory effect on this front on primary production, and this result is attributed to this front being weak in terms of density (erga et al. 2014). a related study found high secondary production at the pf, but also in surrounding waters (basedow et al. 2014). along with sea temperature rise and increased advection of atlantic or pacific waters into the arctic ocean, characteristics and location of pf are likely to change, influencing energy transfer to higher trophic levels. northward displacement of the pf in the barents sea was predicted from coupled biophysical model for a b2 intergovernmental panel on climate change scenario (huse & ellingsen 2008). simulations showed that pf displacement in the barents sea had an impact on the distribution and spawning of capelin (mallotus villosus). the model predicted increased production and large interannual variability in the barents sea, characteristic for the miz (wassmann et al. 2010). permanent ice cover*high arctic we have only limited knowledge of the energy flow and trophic structure of arctic deep-sea regions. very little is known about the linkages of the seasonal production pulse to the deep-sea communities in the high arctic or even about the deep-sea communities themselves. therefore, many of the assumptions made for shelf arctic systems may not be valid for the central arctic. the few available studies from the central arctic report extremely low species richness and biomass (kröncke 1994, 1998) for meiofaunal (vanreusel et al. 2000) and macrofaunal taxa (kröncke 1994, 1998; clough et al. 1997; deubel 2000; bluhm et al. 2005; bluhm, ambrose et al. 2011), as well as a decrease in diversity with increasing water depth (kröncke et al. 1998). primary productivity in the central arctic is limited by light and nutrients. constrained by light, sea-ice algal primary production occurs only from may to august and may be further restricted by ice thickness and snow cover (rysgaard et al. 2001; nicolaus et al. 2012). nutrient supply on the other hand is constrained by stratification (bourgain & gascard 2011) and may not be sufficient in the central arctic (tremblay et al. 2008). estimated average primary production in the ice-covered central arctic is low, on the order of 1 to 25 g c m �2 y �1 (wheeler et al. 1997; wassmann et al. 2010), with ice algae production contributing from 0 to 80% (gosselin et al. 1997; wassmann et al. 2008). bauerfeind et al. (2009) suggested very efficient processing of carbon within the water column, with b10% of primary production reaching the seafloor in the deep sea (fram strait). low primary production and export flux result in low abundance of suspension feeders in the deep basins (kröncke et al. 1998) and a dominance of deposit feeders (van oevelen et al. 2011). however, suspension feeders in the deep sea are known to utilize re-suspended material and directly compete with deposit feeders on the scarce food available (lampitt et al. 1993; iken et al. 2001). although most benthic species in the deep sea seem to be able to cope with refractory material (van oevelen et al. 2011), fresh phytodetritus may also arrive to the seafloor and support suspension feeders and surface deposit feeders such as cumaceans (iken et al. 2005). also, boetius et al. (2013) reported fast response to melosira falls of opportunistic deep-sea megafauna species, such as the holothurians kolga hyalina and elpidia heckeri, and the ophiurid ophiostriatus striatus. increased sediment respiration rates showed that sediment bacteria also profited from this ice algae deposition (boetius et al. 2013). however, infauna were probably unable to utilize ice algae as infaunal burrows and tubes were rarely seen in the under-water video footage, although they are common in other deep-sea basins with seasonally sedimenting phytoplankton blooms (boetius et al. 2013). in the arctic deep-sea plains, benthic communities are constrained by strong seasonality and limited food supply (iken et al. 2005); ice algae production related to permanent sea-ice cover and export fluxes of organic matter to the seafloor are therefore important in these ecosystems. benthic trophic pathways in the deep arctic ocean are longer than on the shelf region or in the temperate deep sea owing to the continuous recycling and thus isotopic enrichment of food particles in the benthic system, while a more direct link to fresh phytodetritus exists in the pelagic system (iken et al. 2005; bergmann et al. 2009). in the past, the central arctic ocean has been covered with multi-year ice, but the marked decline in multi-year ice (maslanik et al. 2011) suggests that the region could be ice-free by the summer of 2040 (polyakov et al. 2010). moreover, according to the latest publications, the central arctic ocean is no longer covered with multi-year ice (polyakov et al. 2012) while the remnant multi-year sea ice occurs along the north-west flank of the canadian arctic archipelago, where it can drift southwards, out over the southern beaufort sea and northwards (barber et al. 2009). if we assume that areas formerly covered m. kędra et al. status and trends in the structure of arctic benthic food webs citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 with thick multi-year ice will have a thinner ice cover, permitting higher primary production, we can project a higher annual primary production level due to light availability, provided nutrients are available, which may not be the case in the basins (codispoti et al. 2013; matrai et al. 2013). a massive under-ice bloom was reported recently from consolidated ice pack in the northern chukchi sea, with phytoplankton biomass beneath the ice being about fourfold greater than in open water (arrigo et al. 2012). similar massive blooms might be widespread in the arctic ocean, in relation to the lower nutrient levels available. more work is needed to determine the extent to which such blooms are controlled by thinning sea ice and proliferating melt pond fractions and how they affect marine ecosystems. although higher light penetration will promote ice algal growth, low level of nutrients available and progressing climate warming may also reduce the algal growing season through increased thermal or haline stratification, limiting mixing and upward nutrient transport resulting in smaller export flux to the seafloor (carmack & wassmann 2006; slagstad et al. 2011). in addition, if zooplankton abundance increases as warmer atlantic and pacific waters are transported into the arctic ocean (hirche & kosobokova 2007), the grazing pressure will increase, leading to increased retention of organic carbon in the water column. some studies suggest that the flux of ice algae and ice-related particulate organic matter will decrease along with sea-ice retreat and loss of multi-year ice (forest et al. 2010). this may lead to decreased carbon deposition at the deep seafloor to already food-limited fauna, but these shifts are not expected to be rapid (van oevelen et al. 2011). yet, the lack of reliable baseline information makes predictions difficult and identifying change nearly impossible (wassmann et al. 2011). gaps and recommendations despite numerous recent studies (table 2, fig. 1), major gaps remain in the knowledge of general processes governing biodiversity, food-web structure, trophic transfer efficiency and functioning of arctic ecosystems. since different regions of the arctic have received varying levels of scientific attention (table 2, fig. 1), these recommendations may not apply to the whole arctic and should be treated as more general statements. given that these processes are not yet clearly quantified, any attempt to project changes that may occur in arctic food webs in the future, such as that suggested in this review, should be taken cautiously. most predictions are qualitative and biased towards conditions on the shelves, while quantitative ones remain scarce (but see zhang et al. 2010; popova et al. 2012; slagstad et al. 2011). since a lot of changes in the arctic food webs are expected to be driven by a shift from decreasing sea-ice algae and an increase in pelagic production, observational, experimental and modelling approaches of the present-day coupling of these two production pathways in food webs should first be implemented, and subsequently combining different scientific methods will allow for the establishment of projection methodologies for arctic ecosystems. large-scale studies of food webs across arctic regions highlighting inherent differences among regions are still lacking. although deep-sea areas are still under-sampled because of the difficulty in accessing field sites, and a consistent sampling design does not exist arctic-wide, the lack of sampling is not the main issue. throughout the years data on the response of different benthic communities to climate change and on food webs have increased from multiple projects. these include hausgarten, the alfred wegener institute’s long-term monitoring programme in fram strait (soltwedel et al. 2005), with data over 10 years, and the distributed biological observatory (dbo), an international initiative in the pacific arctic (grebmeier et al. 2010), with data over 30 years, including time series from long-term census of the arctic (rusalca) programme. while efforts to sample the arctic ocean must and will continue, a primary ambition should be to gather, combine and analyse existing information. such efforts have been undertaken recently regarding arctic biodiversity (e.g., bluhm, ambrose et al. 2011; gill et al. 2011; piepenburg et al. 2011), food sources and trophic interactions, e.g., the pacific marine arctic regional synthesis project (pacmars), although consistent data on food webs (sensu species interactions) are still missing. similar-format databases should be established, centralized and made easily accessible to scientists at the international level, in order to explore the issues mentioned in this review, such as the pacmars effort. then, to promote further consistency of data collection, a standardized data sampling protocol should be implemented when possible to facilitate data gathering and data set use. designated sampling stations should be sampled throughout months and years to monitor seasonal and long-term changes in biodiversity (gill et al. 2011). apart from species identity, functional lifestyle and life-cycle traits should be recorded, which would allow detecting and monitoring changes in ecosystem functioning (cadotte et al. 2011). to complement field sampling and database design, empirical manipulations to be performed in situ, in several places in the arctic, should be encouraged. such studies should address quantitative aspects of the impact of global warming on food-web length and components, status and trends in the structure of arctic benthic food webs m. kędra et al. 12 (page number not for citation purpose) citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 including primary production rates, grazing rates and growth rates at higher trophic levels, in order to estimate changes in trophic transfer efficiency in arctic food webs. studies of diets relative to availability of different foods are also critical to food-web analyses, especially to predicting response to changing conditions. in situ and laboratory experiments could be complemented by use of numerical modelling. trophic network modelling methods that are widely used in other ecosystems could be implemented in the arctic to understand food-web structure, the effects of external threats (e.g., increased fisheries pressure, invasive species) on food-web dynamics, and to quantify energy transfers between trophic levels, in conjunction with empirical work (e.g., van oevelen et al. 2011). results can be subsequently used to fuel models (e.g., provide nutrient�phytoplankton�zooplankton model parameters). since data are still lacking, this could be achieved by using well-established predesigned software able to deal with missing parameters such as ecopath (pauly et al. 2000), especially for fishery scenarios, and the linear inverse model package lim in the r statistical software package (van oevelen et al. 2010). these models have the advantage of including both pelagic and benthic compartments and are able to quantify the strength of pelagic�benthic coupling. although such models have been implemented for some arctic regions (e.g., trites et al. 1999; dommasnes et al. 2001; pedersen & zeller 2001; aydin et al. 2002; whitehouse et al. 2014), they need to be updated, integrated and compared, especially after the recent environmental changes that have occurred in the arctic. stability analysis methods can also be coupled with the mass-balance modelling framework to provide insights into arctic food-web structure and intrinsic properties (neutel et al. 2002). such methods may comprise analyses of stable-states of population or community dynamics, and analyses of food-web properties through determination of eigenvectors, resilience and persistence levels, and equilibrium shifts. at the theoretical level, population, metapopulation, community and metacommunity dynamic models can be implemented to understand how intraand interspecific interactions and connectivity affect diversity at different spatial scales, such as between the different arctic regions and the surrounding oceans (carr et al. 2011; hardy et al. 2011). predicted ice melt and changing hydrodynamics may alter connectivity between distant arctic populations, in turn affecting community composition and food-web structure. such advances could provide valuable contributions to predicting future trends of biodiversity and food-web structure in the arctic. statistical modelling, particularly quantification of species�environment relationships at large scales, should be assessed once data are pooled across arctic regions. the statistical methods developed to date and applied to different biological organisms are an efficient means to disentangle the effects of environmental gradients (both in space and time) on community structure (dray et al. 2012). even though these methods are often based on species, they can be applied to functional groups to assess trait�environment relationships, reinforcing the need to monitor species traits during field sampling. since environmental changes in the arctic may affect species traits, the whole ecosystem functioning may be altered, and studying functional traits is a good way to assess ecosystem functioning and trophic transfer efficiency (mcgill et al. 2006; cadotte et al. 2011). conclusions: winners and losers arctic marine ecosystems are currently subjected to accelerating climate warming and fast progressing sea-ice retreat. although our knowledge of ecosystem functioning and processes still has significant gaps, and the scale and magnitude of climate change remain largely unknown, some qualitative predictions on the fate of arctic marine food webs are possible. in very general terms, among the ‘‘winners’’ will likely be boreal species as their populations tend to follow increasing sea temperature by shifting their ranges northward (and likely losing ground in the south), and pelagic species, mainly zooplankton, whose abundance and biomass may increase with increasing water column primary production related to more and earlier open water over the arctic shelves. pelagic feeding animals, like some fish, marine mammals and seabirds may consequently increase in abundance. species classified as generalists are more likely to adapt to new conditions than specialists. groups that will likely be among the ‘‘losers’’ include arctic species, especially those that are ice-dependent, as they will be most strongly affected by rising temperatures and diminishing habitat. benthic species may decrease in biomass with increased pelagic grazing and recycling in the water column, which may lead to reduced amount or quality of organic matter settling from the water column to the seafloor. this will affect benthic feeding marine mammals and seabirds, whose foraging areas will become less productive and prey less available. food webs will likely lengthen at the low trophic levels, lowering trophic transfer efficiency and thereby lowering the percentage of primary production that reaches top predators. since many species at the base of the arctic food webs are seaice dependent, the stability of food webs will likely be negatively affected in areas where trophic redundancy is low. collaborative multidisciplinary research is necessary m. kędra et al. status and trends in the structure of arctic benthic food webs citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 13 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 if we are to fully understand the processes and linkages between arctic marine environments and their associated food webs in the face of a changing north. acknowledgements this publication is an output of the first joint arctic in rapid transition (art) and association of polar early career scientists science workshop, in sopot, poland, 23�26 october 2012. this cross-cutting initiative was generously supported by the international arctic science committee, the prince albert ii of monaco foundation, the polish academy of sciences and institute of oceanology, the polish scientific committee on oceanic research, the international arctic research center, the french national center for scientific research�laval takuvik joint laboratory, the alfred wegener institute for polar and marine research and the department of fisheries and oceans canada. the support and initiative of art is gratefully acknowledged. financial support for preparation of individual components of this review was provided by the following sources: national science centre grant no. dec-2013/08/m/nz8/00592 for mk; ressources aquatiques québec and the natural sciences and engineering research council of canada for cm; a natural sciences and engineering research council of canada (nserc) postgraduate scholarship and w. garfield weston award foundation for esc; grants from the us national science foundation (nsf-dpp-1204082) and the national oceanic and atmospheric administration (na08oar4310608) for jmg; the partnership for observations of the global oceans�scor fellowship programme 2013 and president’s grant mk-128.2014.1 and russian foundation for basic research grant no. 14-01-31053 for dk. sd would like to acknowledge dr greg thiemann, nserc, environment canada and the molson foundation. references amante c. & eakins b.w. 2009. etopo1 1 arc-minute global relief model: procedures, data sources and analysis. pp. 1�19. noaa technical memorandum nesdis ngdc-24. boulder, co: national oceanic and atmospheric administration. ambrose w.g. jr. & renaud p.e. 1995. benthic response to water column productivity patterns: evidence for benthic� pelagic coupling in the northeast water polynya. journal of geophysical research*oceans 100, 4411�4421. ambrose w.g. jr. & renaud p.e. 1997. does a pulsed food supply to the benthos affect polychaete recruitment patterns in the northeast water polynya? journal of marine systems 10, 483�495. anderson l.g. & kaltin s. 2001. carbon fluxes in the arctic ocean*potential impact by climate change. polar research 20, 225�232. arrigo k.r., perovich d.k., pickart r.s., brown z.w., van dijken g.l., lowry k.e., mills m.m., palmer m.a., balch w.m., bahr f., bates n.r., benitez-nelson c., bowler b., brownlee e., ehn j.k., frey k.e., garley r., laney s.r., lubelczyk l., mathis j., matsuoka a., mitchell b.g., moore g.w.k., ortega-retuerta e., pal s., polashenski c.m., reynolds r.a., schieber b., sosik h.m., stephens m. & swift j.h. 2012. massive phytoplankton blooms under arctic sea ice. science 336, 1408. arrigo k.r., perovich d.k., pickart r.s., brown z.w., van dijken g.l., lowry k.a., mills m.m., palmer m.a., balch w.m., bates n.r., benitez-nelson c.r., brownlee e., frey k.e., laney s.r., mathis j., matsuoka a., mitchell b.g., moore g.w.k., reynolds r.a., sosik h.m. & swift j.h. 2014. phytoplankton blooms beneath the sea ice in the chukchi sea. deep-sea research part ii 105, 85�104. arrigo k.r. & van dijken g.l. 2011. secular trends in arctic ocean net primary production. journal of geophysical research*oceans 116, c09011, doi: 10.1029/2011jc007151. arrigo k.r., van dijken g. & pabi s. 2008. impact of a shrinking arctic ice cover on marine primary production. geophysical research letters 35, l19603, doi: 10.1029/ 2008gl035028. auel h., harjes m., da rocha r., stübing d. & hagen w. 2002. lipid biomarkers indicate different ecological niches and trophic relationships of the arctic hyperiid amphipods, themisto abyssorum and t. libellula. polar biology 25, 374�383. aydin k. & mueter f. 2007. the bering sea*a dynamic food web perspective. deep-sea research part ii 54, 2501�2525. aydin k.y., lapko v.v., radchenko v.i. & livingston p.a. 2002. a comparison of the eastern bering and western bering sea shelf and slope ecosystems through the use of mass-balance food web models. noaa technical memorandum nmfs-afsc-130. seattle, wa: national oceanoic and atmospheric administration. bachy c., lópez-garcı́a p., vereshchaka a. & moreira d. 2011. diversity and vertical distribution of microbial eukaryotes in the snow, sea ice and seawater near the north pole at the end of the polar night. frontiers in microbiology 2, article no. 106, doi: 10.3389/fmicb.2011.00106. barber d.g., galley r., asplin m.g., de abreu r., warner k.a., pućko m., gupta m., prinsenberg s. & julien s. 2009. perennial pack ice in the southern beaufort sea was not as it appeared in the summer of 2009. geophysical research letters 36, l24501, doi: 10.1029/2009gl041434. basedow s.l., zhou m. & tande k.s. 2014. secondary production at the polar front, barents sea, august 2007. journal of marine systems 130, 147�159. bauerfeind e., nöthig e.m., beszczyńska a., fahl k., kaleschke l., kreker k., klages m., soltwedel t., lorenzen c. & wegner j. 2009. particle sedimentation patterns in the eastern fram strait during 2000�2005: results from the arctic long-term observatory hausgarten. deep-sea research part i 56, 1471�1487. status and trends in the structure of arctic benthic food webs m. kędra et al. 14 (page number not for citation purpose) citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 belkin i.m., cornillon p. & ullman d. 2003. ocean fronts around alaska from satellite sst data. in: proceedings of the american meteorological society’s 7th conference on the polar meteorology and oceanography and joint symposium on highlatitude climate variations, 12�16 may, hyannis, ma. paper 12.7. boston: american meteorological society. berge j., heggland k., lønne o.j., cottier f., hop h., gabrielsen g.w., nøttestad l. & misund o.a. 2015. first records of atlantic mackerel (scomber scombrus) from the svalbard archipelago, norway, with possible explanations for the extension of its distribution. arctic 68, 54�61. berge j., johnsen g., nilsen f., gulliksen b. & slagstad d. 2005. ocean temperature oscillations enable reappearance of blue mussels mytilus edulis in svalbard after 1000 years of absence. marine ecology progress series 303, 167�175. bergmann m., dannheim j., bauerfeind e. & klages m. 2009. trophic relationships along a bathymetric gradient at the deep-sea observatory hausgarten. deep-sea research part i 56, 408�424. birdlife international. 2012a. alle alle. in: iucn red list of threatened species. version 2014.1. accessed on the internet at www.iucnredlist.org on 3 july 2014. birdlife international. 2012b. fulmarus glacialis. in: iucn red list of threatened species. version 2014.1. accessed on the internet at www.iucnredlist.org on 3 july 2014. birdlife international. 2012c. somateria fischeri. in: iucn red list of threatened species. version 2014.1. accessed on the internet at www.iucnredlist.org on 3 july 2014. blake j.a. 1993. life history analysis of five dominant infaunal polychaete species from the continental slope off north carolina. journal of marine biology association of united kingdom 73, 123�141. blanchard a.l., feder h.m. & hoberg m.k. 2010. temporal variability of benthic communities in an alaskan glacial fjord, 1971�2007. marine environmental research 69, 95�107. bluhm b., macdonald i.r., debenham c. & iken k. 2005. macroand megabenthic communities in the high arctic canada basin: initial findings. polar biology 28, 218�231. bluhm b.a., ambrose w.g. jr., bergmann m., clough l.m., gebruk a.v., hasemann c., iken k., klages m., macdonald i.r., renaud p.e., schewe i., soltwedel t. & wlodarskakowalczuk m. 2011. diversity of the arctic deep-sea benthos. marine biodiversity 41, 87�107. bluhm b.a., coyle k.o., konar b. & highsmith r.c. 2007. high gray whale relative abundances associated with an oceanographic front in the south-central chukchi sea. deep-sea research part ii 54, 2919�2933. bluhm b.a. & gradinger r. 2008. regional variability in food availability for arctic marine mammals. ecological applications 18, 77�96. bluhm b.a., gradinger r. & hopcroft r.r. 2011. arctic ocean diversity synthesis. marine biodiveristy 41, 1�4. boetius a., albrecht s., bakker k., bienhold c., felden j., fernandez-mendez m., hendricks s., katlein c., lalande c., krumpen t., nicolaus m., peeken i., rabe b., rogacheva a., rybakova e., somavilla r. & wenzhofer f. 2013. export of algal biomass from the melting arctic sea ice. science 339, 1430�1432. bourgain p. & gascard j.c. 2011. the arctic ocean halocline and its interannual variability from 1997 to 2008. deep-sea research part i 58, 745�756. cadotte m., carscadden k. & mirotchnick n. 2011. beyond species: functional diversity and the maintenance of ecological processes and services. journal of applied ecology 48, 1079�1087. campbell r.g., sherr e.b., ashjian c.j., plourde s., sherr b.f., hill v. & stochwell d.a. 2009. mesozooplankton prey preference and grazing impact in the western arctic ocean. deep-sea research part ii 56, 1274�1289. carmack e. & chapman d.c. 2003. wind-driven shelf/basin exchange on an arctic shelf: the joint roles of ice cover extent and shelf-break bathymetry. geophysical research letters 30, 1778. carmack e. & wassmann p. 2006. food webs and physical� biological coupling on pan-arctic shelves: unifying concepts and comprehensive perspectives. progress in oceanography 71, 446�477. carmack e.c., macdonald r.w. & jasper s. 2004. phytoplankton productivity on the canadian shelf of the beaufort sea. marine ecology progress series 277, 37�50. carr c.m., hardy s.m., brown t.m., macdonald t.a. & hebert p.d.n. 2011. a tri-oceanic perspective: dna barcoding reveals geographic structure and cryptic diversity in canadian polychaetes. plos one 6, e22232, doi: 10.1371/journal. pone.0022232. chambouvet a., morin p., marie d. & guillou l. 2008. control of toxic marine dinoflagellates blooms by serial parasitic killers. science 322, 1254�1257. clarke a. & harris c.m. 2003. polar marine ecosystems: major threats and future change. environmental conservation 30, 1�25. clough l.m., ambrose w.g. jr., cochran j.k., barnes c., renaud p.e. & aller r.c. 1997. infaunal density, biomass and bioturbation in the sediments of the arctic ocean. deep-sea research part ii 44, 1683�1704. clough l.m., renaud p.e. & ambrose w.g. jr. 2005. impacts of water depth, sediment pigment concentration, and benthic macrofaunal biomass on sediment oxygen demand in the western arctic ocean. canadian journal of fisheries and aquatic sciences 62, 1756�1765. codispoti l.a., kelly v., thessen a., matrai p., suttles s., hill v., steele m. & light b. 2013. synthesis of primary production in the arctic ocean: iii. nitrate and phosphate based estimates of net community production. progress in oceanography 110, 126�150. collins r.e. & deming j.w. 2011. abundant dissolved genetic material in arctic sea ice. part ii: viral dynamics during autumn freeze-up. polar biology 34, 1831�1841. comeau a.m., li w.k., tremblay j.e., carmack e. & lovejoy c. 2011. arctic ocean microbial community structure before and after the 2007 record sea ice minimum. plos one 6, e27492. doi: 10.1371/journal.pone.0027492. m. kędra et al. status and trends in the structure of arctic benthic food webs citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 15 (page number not for citation purpose) http://www.iucnredlist.org on 3 july 2014 http://www.iucnredlist.org http://www.iucnredlist.org http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 comeau a.m., philippe b., thaler m., gosselin m., poulin m. & lovejoy c. 2013. protists in arctic drift and land-fast ice. journal of phycology 49, 229�240. comiso j.c. 2012. large decadal decline of the arctic multiyear ice cover. journal of climate 25, 1176�1193. cooper l.w., grebmeier j.m., larsen i.l., egorov v.g., theodorakis c., kelly h.p. & lovvorn j. 2002. seasonal variation in sedimentation of organic materials in the st. lawrence island polynya region, bering sea. marine ecology progress series 226, 13�26. daase m., verpe ø. & falk-petersen s. 2014. non-consumptive mortality in copepods: occurrence of calanus spp. carcasses in the arctic ocean during winter. journal of plankton research 36, 129�144. darnis g., robert d., pomerlau c., link h., archambault p., nelson r.j., geoffroy m., tremblay j.e., lovejoy c., ferguson s., hunt b.v. & fortier l. 2012. current state and trends in canadian arctic marine ecosystems: ii. heterotrophic food web, pelagic�benthic coupling, and biodiversity. climatic change 115, 179�205. daufresne m., lengfellener k. & sommer u. 2009. global warming benefits the small in aquatic ecosystems. proceedings of the national academy of sciences of the united states of america 106, 12788�12793. david c., lange b., rabe b. & flores h. 2015. community structure of under-ice fauna in the eurasian central arctic ocean in relation to environmental properties of sea-ice habitats. marine ecology progress series 522, 15�32. de laender f., van oevelen d., soetaert k. & middelburg j.j. 2010. carbon transfer in herbivoreand microbial loopdominated pelagic food webs in the southern barents sea during spring and summer. marine ecology progress series 398, 93�107. deubel h. 2000. struktureigenschaften und nahrungsbedarf der zoobenthosgemeinschaften im bereich des lomonossowrückens im arktischen ozean. (structures and nutrition requirements of macrozoobenthic communities in the area of the lomonossov ridge in the arctic ocean.) berichte zur polarund meeresforschung 370. bremerhaven: alfred wegener institute. dewicke a., rottiers v., mees j. & vincx m. 2002. evidence for an enriched hyperbenthic fauna in the frisian front (north sea). journal of sea research 47, 121�139. dommasnes a., christensen v., ellertsen b., kvamme c., melle w., nøttestad l., pedersen t., tjelmeland s. & zeller d. 2001. an ecopath model for the norwegian sea and barents sea. in s. guénette et al. (eds.): fisheries impacts on north atlantic ecosystems: models and analyses. fisheries centre research reports. pp. 213�240. vancouver: fisheries centre, university of british columbia. dray s., pelissier r., couteron p., fortin m.j., legendre p., peres-neto p.r., bellier e., bivand r., blanchet f.g., de caceres m., dufour a.b., heegaard e., jombart t., munoz f., oksanen j., thiouloise j. & wagner h.h. 2012. community ecology in the age of multivariate multiscale spatial analysis. ecological monographs 82, 257�275. duarte c.m. 2007. marine ecology warms up to theory. trends in ecology and evolution 22, 331�333. dunbar r.b. & leventer a.r. 1987. sediment fluxes beneath fast ice: october 19 86 through february 1987. antarctic journal of the united states 22, 112�115. dunton k.h., schonberg s.v. & cooper l.w. 2012. food web structure of the alaskan nearshore shelf and estuarine lagoons of the beaufort sea. estuaries and coasts 35, 416�435. dunton k.h., weingartner t. & carmack e.c. 2006. the nearshore western beaufort sea ecosystem: circulation and importance of terrestrial carbon in arctic coastal food webs. progress in oceanography 71, 362�378. erga s.r., ssebiyonga n., hamre b., frette ø., rey f. & drinkwater k. 2014. nutrients and phytoplankton biomass distribution and activity at the barents sea polar front during summer near hopen and storbanken. journal of marine systems 130, 181�192. falkowski p.g., barber r.t. & smetacek v. 1998. biogeochemical controls and feedbacks on ocean primary production. science 281, 200�206. falk-petersen s., mayzaud p., kattner g. & sargent j. 2009. lipids and life strategy of arctic calanus. marine biology research 5, 18�39. falk-petersen s., pavlov v., timofeev s. & sargent j.r. 2006. climate variability and possible effects on arctic food chains: the role of calanus. in j.b. ørbæk et al. (eds.): arctic alpine ecosystems and people in a changing environment. pp. 147�166. berlin: springer. falk-petersen s., sargent j.r., lønne o.j. & timofeev s. 1999. functional biodiversity in lipids of antarctic zooplankton: calanoides acutus, calanus propinquus, thysanoessa macrura and euphausia crystallorophias. polar biology 21, 37�47. feder h.m., iken k., blanchard a.l., jewett s.c. & schonberg s. 2011. benthic food web structure in the southerneastern chukchi sea: an assessment using d13c and d15n analyses. polar biology 34, 521�532. feder h.m., jewett s.c. & blanchard a. 2007. southeastern chukchi sea (alaska) macrobenthos. polar biology 30, 261�275. fetterer f., knowles k., meier w. & savoie m. 2002 (updated 2009). sea ice index. g02135. boulder, co: national snow and ice data center. accessed on the internet at http://dx. doi.org/10.7265/n5qj7f7w on 07.07.2014 forest a., wassmann p., slagstad d., bauerfeind e., nöthig e.m. & klages m. 2010. relationships between primary production and vertical particle export at the atlantic�arctic boundary (fram strait, hausgarten). polar biology 33, 1733�1746. fortier m., fortier l., michel c. & legendre l. 2002. climatic and biological forcing of the vertical flux of biogenic particles under seasonal arctic sea ice. marine ecology progress series 225, 1�16. fortier l., pascal s., josee m. & barber d. 2006. survival of arctic cod larvae (boreogadus saida) in relation to sea ice and temperature in the northeast water polynya (greenland sea). canadian journal of fisheries and aquatic sciences 63, 1608�1616. status and trends in the structure of arctic benthic food webs m. kędra et al. 16 (page number not for citation purpose) citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 http://dx.doi.org/10.7265/n5qj7f7w http://dx.doi.org/10.7265/n5qj7f7w http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 frey k.e. & mcclelland j.w. 2009. impacts of permafrost degradation on arctic river biogeochemistry. hydrological processes 23, 169�182. frey k.e., mcclelland j.w., holmes r.m. & smith l.c. 2007. impacts of climate warming and permafrost thaw on the riverine transport of nitrogen and phosphorus to the kara sea. journal of geophysical research*biogeosciences 112, g04s58, doi: 10.1029/2006jg000369. gill m.j., crane k., hindrum r., arneberg p., bysveen i., denisenko n.v., gofman v., grant-friedman a., gudmundsson g., hopcroft r.r., iken k., labansen a., liubina o.s., melnikov i.a., moore s.e., reist j.d., sirenko b.i., stow j., ugarte f., vongraven d. & watkins j. 2011. arctic marine biodiversity monitoring plan (cbmp-marine plan). caff monitoring series report 3. akureyri: conservation of arctic flora and fauna international secretariat. gosselin m., lecasseur m., wheeler p.a., horner r.a. & booth b.c. 1997. new measurements of phytoplankton and ice algal production in the arctic ocean. deep-sea research part ii 44, 1623�1644. gradinger r. 1995. climate change and biological oceanography of the arctic ocean. philosophical transactions of the royal society of london series a 352, 277�286. gradinger r. 2009. sea ice algae: major contributors to primary production and algal biomass in the chukchi and beaufort seas during may/june 2002. deep-sea research part ii 56, 1201�1212. gradinger r. & bluhm b. 2004. in situ observations on the distribution and behavior of amphipods and arctic cod (boreogadus saida) under the sea ice of the high arctic canadian basin. polar biology 27, 595�603. grebmeier j.m. 2012. shifting patterns of life in the pacific arctic and sub-arctic seas. annual review of marine science 4, 63�78. grebmeier j.m. & barry j.p. 2007. benthic processes in polynyas. in w. smith jr. & d. barber (eds.): polynyas: windows to the world. pp. 363�390. amsterdam: elsevier. grebmeier j.m., cooper l.w., feder h.m. & sirenko b.i. 2006. ecosystem dynamics of the pacific-influenced northern bering and chukchi seas in the amerasian arctic. progress in oceanography 71, 331�361. grebmeier j.m. & mcroy c.p. 1989. pelagic�benthic coupling on the shelf of the northern bering and chukchi seas. iii. benthic food supply and carbon cycling. marine ecology progress series 53, 79�91. grebmeier j.m., mcroy c.p. & feder h.m. 1988. pelagic� benthic coupling on the shelf of the northern bering and chukchi seas. i. food supply source and benthic biomass. marine ecology progress series 48, 57�67. grebmeier j.m., moore s.e., overland j.e., frey k.e. & gradinger r. 2010. biological response to recent pacific arctic sea ice retreats. eos, transactions of the american geophysical union 91, 161�162. grebmeier j.m., overland j., moore s.e., farley e.v., carmack e.c., cooper l.w., frey k.e., helle j.h., mclaughlin f.a. & mcnutt s.l. 2006. a major ecosystem shift in the northern bering sea. science 311, 1461�1464. gupta m., barber d.g., scharien r.k. & isleifson d. 2014. detection and classification of surface roughness in an arctic marginal sea ice zone. hydrological processes 28, 599�609. hansell d.a. & ducklow h.w. 2003. bacterioplankton distribution and production in the bathypelagic ocean: directly coupled to particulate organic carbon export? limnology and oceanography 48, 150�156. hardy s.m., carr c.m., hardman m., steinke d., corstorphine e. & mah c. 2011. biodiversity and phylogeography of arctic marine fauna: insights from molecular tool. marine biodiversity 41, 195�210. hegseth e.n. 1998. primary production of the northern barents sea. polar research 17, 113�123. herbert r.j.h., southward a.j., sheader m. & hawkins s.j. 2007. influence of recruitment and temperature on distribution of intertidal barnacles in the english channel. journal of the marine biological association of the united kingdom 87, 487�499. higdon j.w. & ferguson s. 2009. loss of arctic sea ice causing punctuated change in sightings of killer whales (orcinus orca) over the past century. ecological applications 19, 1365� 1375. higgins m.e. & cassano j.j. 2009. impacts of reduced sea ice on winter arctic atmospheric circulation, precipitation and temperature. journal of geophysical research*atmospheres 114, d16107, doi: 10.1029/2009jd011884. hirche h.j. & kosobokova k.n. 2007. distribution of calanus finmarchicus in the northern north atlantic and arctic ocean*expatriation and potential colonization. deep-sea research part ii 54, 2729�2747. hobbs r.j., arico s., aronson j., baron j.s., bridgewater p., cramer v.a., epstein p.r., ewel j.j., klink c.a., lugo a.e., norton d., ojima d., richardson d.m., sanderson e.w., valladeres f., vila m., zamora r. & zobel m. 2006. novel ecosystems: theoretical and management aspects of the new ecological world order. global ecology and biogeography 15, 1�7. hobson k.a., ambrose w.g. jr. & renaud p.e. 1995. sources of primary production, benthic�pelagic coupling, and throphic relationships within the northeast water polynya: insights from d13cand d15n analysis. marine ecology progress series 128, 1�10. hodges l.r., bano n., hollibaugh j.t. & yager p.l. 2005. illustrating the importance of particulate organic matter to pelagic microbial abundance and community structure*an arctic case study. aquatic microbial ecology 40, 217�227. hollowed a.b., planque b. & loeng h. 2013. potential movement of fish and shellfish stocks from the sub-arctic to the arctic ocean. fisheries oceanography 22, 355�370. hop h. & gjøsæter h. 2013. polar cod (boreogadus saida) and capelin (mallotus villosus) as key species in marine food webs of the arctic and the barents sea. marine biology research 9, 878�894. hop h. & pavlova o. 2008. distribution and biomass transport of ice amphipods in drifting sea ice around svalbard. deepsea research part ii 55, 2292�2307. m. kędra et al. status and trends in the structure of arctic benthic food webs citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 17 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 howard-jones m.h., ballard v.d., allen a.e., frischer m.e. & verity p.g. 2002. distribution of bacterial biomass and activity in the marginal ice zone of the central barents sea during summer. journal of marine systems 38, 77�91. hunt g.l. jr., blanchard a., boveng p., dalpadado p., drinkwater k., eisner l., hopcroft r.r., kovacs k., norcross b.l., renaud p.e., reigstad m., renner m., skjoldal h.r., whitehause a. & woodgate r. 2013. the barents and chukchi seas: comparison of two arctic shelf ecosystems. journal of marine science 109�110, 43�68. hunt g.l. jr & stabeno p.j. 2002. climate change and the control of energy flow in the southeastern bering sea. progress in oceanography 55, 5�22. huse g. & ellingsen i. 2008. capelin migrations and climate change*a modelling analysis. climatic change 87, 177�197. iken k., bluhm b. & dunton k. 2010. benthic food-web structure under differing water mass properties in the southern chukchi sea. deep-sea research part ii 57, 71�85. iken k., bluhm b.a. & gradinger r. 2005. food web structure in the high arctic canada basin: evidence from d13c and d15n analysis. polar biology 28, 238�249. iken k., brey t., wand u., voigt j. & junghans p. 2001. food web structure of the benthic community at the porcupine abyssal plain (ne atlantic): a stable isotope analysis. progress in oceanography 50, 383�405. iverson r.l., whitledge t.e. & goering j.j. 1979. finestructure of chlorophyll and nitrate in the southeastern bering sea shelf break front. nature 281, 664�666. jefferson t.a., karkzmarski l., laidre k., o’corry-crowe g., reeves r., rojas-bracho l., secchi e., slooten e., smith b.d., wang j.y. & zhou k. 2012. delphinapterus leucas. in: iucn red list of threatened species. version 2014.1. accessed on the internet at www.iucnredlist.org on 3 july 2014 ji r., ashjian c.j., campbell r.g., chen c., gao g., davis c.s., cowles g.w. & beardsley r.c. 2012. life history and biogeography of calanus copepods in the arctic ocean: an individual-based modeling study. progress in oceanography 96, 40�56. ji r., jin m. & varpe o. 2013. sea ice phenology and timing of primary production pulses in the arctic ocean. global change biology 19, 734�741. kędra m., kuliński k., walkusz w. & legeżyńska j. 2012. the shallow benthic food web structure in the high arctic does not follow seasonal changes in the surrounding environment. estuarine, coastal and shelf science 114, 183�191. kędra m., renaud p.e., andrade h., goszczko i. & ambrose w.g. jr. 2013. benthic community structure, diversity, and productivity in the shallow barents sea bank (svalbard bank). marine biology 160, 805�819. kirchman d.l., hill v., cottrell m.t., gradinger r., malmstron r.r. & parker a. 2009. standing stocks, production, and respiration of phytoplankton and heterotrophic bacteria in the western arctic ocean. deep-sea research part ii 56, 1237�1248. koszteyn j., timofeev s., weslawski j.m. & malinga b. 1995. size structure of themisto abyssorum (boeck) and themisto libellula (mandt) populations in european arctic seas. polar biology 15, 85�92. kovacs k. 2008. pagophilus groenlandicus. in: iucn red list of threatened species. version 2014.1. accessed on the internet at www.iucnredlist.org on 3 july 2014 kovacs k.m. 2002. bearded seal erignathus barbatus. in w.f. perrin et al. (eds.): encyclopedia of marine mammals. pp. 84� 87. san diego, ca: academic press. kovacs k.m. & lydersen c. 2008. climate change impacts on seals and whales in the north atlantic arctic and adjacent shelf seas. science progress 91, 117�150. kovacs k.m., moore s., lydersen c. & overland j.e. 2011. impacts of changing sea ice conditions on arctic marine mammals. marine biodiversity 41, 181�194. kozlovsky d.g. 1968. a critical evaluation of the trophic level concept. i. ecological efficiencies. ecology 49, 48�60. kritzberg e.s., duarte c.m. & wassmann p. 2010. changes in arctic marine bacterial carbon metabolism in response to increasing temperature. polar biology 33, 1673�1682. kröncke i. 1994. macrobenthos composition, abundance and biomass in the arctic ocean along a transect between svalbard and the makarov basin. polar biology 14, 519�529. kröncke i. 1998. macrofauna communities in the amudsen basin, at the morris jesup rise and at the yermak plateau (eurasian arctic ocean). polar biology 19, 383�392. kröncke i., dippner j.w., heyen h. & zeiss b. 1998. longterm changes in macrofaunal communities off norderney (east frisia, germany) in relation to climate variability. marine ecology progress series 167, 25�36. kubiszyn a.m., piwosz k., wiktor j.m. jr. & wiktor j.m. 2014. the effect of inter-annual atlantic water inflow variability on the planktonic protist community structure in the west spitsbergen waters during the summer. journal of plankton research 36, 1190�1203. kuliński k., kȩdra m., legeżyńska j., głuchowska m. & zaborska a. 2014. particulate organic matter sinks and sources in high arctic fjord. journal of marine systems 139, 27�37. laidre k.l., stirling i., lowry l.f., wiig ø., heide-jørgensen m.p. & ferguson s.h. 2008. quantifying the sensitivity of arctic marine mammals to climate-induced habitat change. ecological applications 18, s97�s125. lalande c., bauerfeind e., nöthig e. & beszczyńska-möller a. 2013. impact of a warm anomaly on export fluxes of biogenic matter in the eastern fram strait. progress in oceanography 109, 70�77. lalande c., grebmeier j.m., wassmann p., cooper l.w., flint m.v. & sergeeva v.m. 2007. export fluxes of biogenic matter in the presence and absence of seasonal sea ice cover in the chukchi sea. continental shelf research 27, 2051�2065. lalande c., nöthig e.m., somavilla r., bauerfeind e., shevchenko v. & okolodkov y. 2014. variability in underice export fluxes of biogenic matter in the arctic ocean. global biogeochemical cycles 28, 571�583. lampitt r.s., hillier w.r. & challenor p.g. 1993. seasonal and dial variation in the open ocean concentration of marine snow aggregates. nature 362, 737�739. status and trends in the structure of arctic benthic food webs m. kędra et al. 18 (page number not for citation purpose) citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 http://www.iucnredlist.org http://www.iucnredlist.org http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 layman c.a., arrington d.a., montaña c.g. & post d.m. 2007. can stable isotope ratios provide for community-wide measures of trophic structure? ecology 88, 42�48. lee s.h., whitledge t.e. & kang s.h. 2007. recent carbon and nitrogen uptake rates of phytoplankton in bering strait and the chukchi sea. continental shelf research 27, 2231�2249. leu e., søreide j., hessen d.o., falk-petersen s. & berge j. 2011. consequences of changing sea-ice cover for primary and secondary producers in the european arctic shelf seas: timing, quantity, and quality. progress in oceanography 90, 18�32. lewis j.r. 1996. coastal benthos and global warming: strategies and problems. marine pollution bulletin 32, 698�700. lewis o.t. 2005. climate change, species-area curves and the extinction crisis. philosophical transactions of the royal society of london series b 361, 163�171. li w.k.w., mclaughlin f.a., lovejoy c. & carmack e. 2009. smallest algae thrive as the arctic ocean freshens. science 326, 539. loeng h. 1991. features of the physical oceanographic conditions of the barents sea. polar research 10, 5�18. lovejoy c., massana r. & pedros-alio c. 2006. diversity and ditribution of marine microbial eukaryotes in the arctic ocean and adjacent seas. applied and environmental microbiology 72, 3085�3095. lovvorn j.r., richman s.e. & grebmeier j.m. 2003. diet and body condition of spectacled eiders wintering in pack ice of the bering sea. polar biology 26, 259�267. lowry l., kovacs k. & burkanov v. 2008. odobenus rosmarus. in: iucn red list of threatened species. version 2014.1. accessed on the internet at www.iucnredlist.org on 3 july 2014 lu p., li z.j., zhang z.h. & dong x.l. 2008. aerial observations of floe size distribution in the marginal ice zone of summer prydz bay. journal of geophysical research*oceans 113, c02011, doi: 10.1029/2006jc003965. mann k.h. & lazier j.r.n. 1996. dynamics of marine ecosystems. biological�physical interactions in the oceans. 2nd edn. oxford: blackwell science. maslanik j., stroeve j., fowler c.w. & emery w. 2011. distribution and trends in arctic sea ice age through spring 2011. geophysical research letters 38, l13502, doi: 10.1029/ 2011gl047735. matrai p.a., olson e., suttles s., hill v., codispoti l.a., light b. & steel m. 2013. synthesis of primary production in the arctic ocean: i. surface waters, 1954�2007. progress in oceanography 110, 93�106. mccann k.s. 2000. the diversity�stability debate. nature 405, 228�233. mcclelland j.w., dery s.j., peterson b.j., holmes r.m. & wood e.f. 2006. a pan-arctic evaluation of changes in river discharge during the latter half of the 20th century. geophysical research letters 33, l06715, doi: 10.1029/ 2006gl025753. mcgill b.j., enquist b.j., weiher e. & westoby m. 2006. rebuilding community ecology from functional traits. trends in ecology and evolotion 21, 178�185. mcphee m.g., morison j.h. & nilsen f. 2008. revisiting heat and salt exchange at the ice�ocean interface: ocean flux and modeling considerations. journal of geophysical research* oceans 113, c06014, doi 10.1029/2007jc004383. megrey b.a. & aydin k.y. 2009. a macrodescriptor perspective of ecological attributes for the bering and barents seas. deep-sea research part ii 56, 2132�2140. miyazaki n. 2002. ringed, caspian, and baikal seals pusa hispida, p. caspica, and p. sibirica. in w.f. perrin et al. (eds.): encyclopedia of marine mammals. pp. 1033�1037. san diego, ca: academic press. moore s.e., grebmeier j.m. & davies j.r. 2003. gray whale distribution relative to forage habitat in the northern bering sea: current conditions and retrospective summary. canadian journal of zoology 81, 734�742. moore s.e. & huntington h.p. 2008. arctic marine mammals and climate change: impacts and resilience. ecological applications 18, 157�165. moore s.e., logerwell e., eisner l., farley e.v. jr., harwood l.a., kuletz k., lovvorn j., murphy j.r. & quakenbush l.t. 2014. marine fishes, birds and mammals as sentinels of ecosystem variability and reorganization in the pacific arctic region. in j.m. grebmeier & w. maslowski (eds.): ecosystem status and trends in a rapidly changing environment. pp. 337� 392. dordrecht, netherlands: springer. moran s.b., lomas m.w., kelly r.p., gradinger r., iken k. & mathis j.t. 2012. seasonal succession of net primary productivity, particulate organic carbon export, and autotrophic community composition in the eastern bering sea. deep-sea research part ii 65�70, 84�97. mueter f.j. & litzow m.a. 2008. sea ice retreat alters the biogeography of the bering sea continental shelf. ecological applications 18, 309�320. müller-navarra d.c. 2008. food web paradigms: the biochemical view on trophic interactions. international review of hydrobiology 93, 489�505. mundy c.j., gosselin m., gratton y., brown k., galindo v., campbell k., levasseur m., barber d., papakyriakou t. & belanger s. 2014. role of environmental factors on phytoplankton bloom initiation under landfast sea ice in resolute passage, canada. marine ecology progress series 497, 39�49. nelson r.j., ashjian c.j., bluhm b.a., conlan k.e., gradinger r.r., grebmeier j.m., hill v.j., hopcroft r.r., hunt b.p.v., joo h.m., kirchman d.l., kosobokova k.n., lee s.h., li w.k.w., lovejoy c., poulin m., sherr e. & young k.v. 2014. in j.m. grebmeier & w. maslowski (eds.): ecosystem status and trends in a rapidly changing environment. pp. 269�336. dordrecht, netherlands: springer. nelson r.j., carmack e., mclaughlin f.a. & cooper g.a. 2009. penetration of pacific zooplankton into the western arctic ocean tracked with molecular population genetics. marine ecology progress series 381, 129�138. neutel a.m., heesterbeek j.a.p. & de ruiter p.c. 2002. stability in real food webs: weak links in long loops. science 296, 1120�1123. nicolaus m., katlein c., maslanik j. & hendricks s. 2012. changes in arctic sea ice result in increasing light transmittance m. kędra et al. status and trends in the structure of arctic benthic food webs citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 19 (page number not for citation purpose) http://www.iucnredlist.org http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 and absorption. geophysical research letters 39, l24501, doi: 10.1029/2012gl053738. o’connor m.i., bruno j.f., gaines s.d., halpern b.s., lester s.e., kinlan b.p. & weiss j.m. 2007. temperature control of larval dispersal and the implications for marine ecology, evolution, and conservation. proceedings of the national academy of sciences of the united states of america 104, 1�6. overland j.e. & stabeno p.j. 2004. is the climate of the bering sea warming and affecting the ecosystem? eos, transactions of the american geophysical union 85, 309�310. palmer m.a., saenz b.t. & arrigo k.r. 2014. impacts of sea ice retreat, thinning, and melt-pond proliferation on the summer phytoplankton bloom in the chukchi sea, arctic ocean. deep-sea research part ii 105, 85�104. parkinson c.l. & comiso j.c. 2013. on the 2012 record low arctic sea ice cover: combined impact of preconditioning and an august storm. geophysical research letters 40, 1356� 1361. pauly d., christensen v., guenette s., pitcher t.j., sumaila u.r., walters c.j., watson r. & zeller d. 2002. towards sustainability in world fisheries. nature 418, 689�695. pauly d., christensen v. & walters c. 2000. ecopath, ecosim, and ecospace as tools for evaluating ecosystem impact of fisheries. ices journal of marine science 57, 697�706. payet j.p. & suttle c. 2013. to kill or not to kill: the balance between lytic and lysogenic viral infection is driven by trophic status. limnology and oceanography 58, 465�474. pearson t.h. & rosenberg r. 1978. macrobenthic succession in relation to organic enrichment and pollution of the marine environment. oceanography and marine biology*an annual review 16, 229�311. pedersen g. & zeller d. 2001. a mass balance model for the west greenland marine ecosystem. in s. guénette et al. (eds.): fisheries impacts on north atlantic ecosystems: models and analyses. pp. 111�127. vancouver: fisheries centre, university of british columbia. perovich d.k., tucker w.b., iii. & krishfield r.a. 1989. oceanic heat flux in the fram strait measured by a drifting buoy. geophysical research letters 16, 995�998. peterson b.j., holmes r.m., mcclelland j.w., vorosmarty c.j., lammers r.b., shiklomanov a.i. & rahmstorf i.a.s.s. 2002. increasing river discharge to the arctic ocean. science 298, 2171�2173. peterson b.j., mcclelland j., curry r., holmes r.m., je w. & aagaar k. 2006. trajectory shifts in the arctic and subarctic freshwater cycle. science 313, 1061�1066. piechura j. & walczowski w. 2009. warming of the west spitsbergen current and sea ice north of svalbard. oceanologia 51, 149�164. piepenburg d., archambault p., ambrose w.g. jr., blanchard a., bluhm b., carroll c.l., conlan k.e., cusson m., feder h.m., grebmeier j.m., jewett s.c., levesque m., petryashev v.v., sejr m.k., sirenko b.i. & włodarska-kowalczuk m. 2011. towards a pan-arctic inventory of the species diversity of the macroand megabenthic fauna of the arctic shelf seas. marine biodiversity 41, 51�70. piepenburg d., blackburn t.h., von dorrien c.f., gutt j., hall p.o., hulth s., kendall m.a., opalinski k.w., rachor e. & schmid m.k. 1995. partitioning of benthic community respiration in the arctic (northwestern barents sea). marine ecology progress series 118, 199�214. piwosz k., spich k., całkiewicz j., weydmann a., kubiszyn a.m. & wiktor j.m. 2015. distribution of small phytoflagellates along an arctic fjord transect. environmental microbiology, doi: 10.1111/1462-2920.12705. piwosz k., walkusz w., hapter r., wieczorek p., hop h. & wiktor j. 2009. comparison of productivity and phytoplankton in a warm (kongsfjorden) and cold (hornsund) spitsbergen fjord in mid-summer 2002. polar biology 32, 549�559. piwosz k., wiktor j.m., niemi a., tatarek a. & michel c. 2013. mesoscale distribution and functional diversity of picoeukaryotes in the first-year sea ice of the canadian arctic. the isme journal 7, 1461�1471. polyakov i.v., timokhov l.a., alexeev v.a., bacon s., dimitrenko i.a., fortier l., frolov i.e., gascard j.c., hansen e., ivanov v.v., laxon s., mauritzen c., perovich d., shimada k., simmons h.l., sokolov v.t., steele m. & toole j. 2010. arctic ocean warming contributes to reduced polar cap. journal of physical oceanography 40, 2743�2756. polyakov i.v., walsh j.e. & kwok r. 2012. recent changes of arctic multiyear sea ice coverage and the likely causes. bulletin of the american meteorological society 93, 145�151. popova e.e., yool a., coward a.c., dupont f., deal c., elliott s., hunke e., jin m., steele m. & zhang j. 2012. what controls primary production in the arctic ocean? results from an intercomparison of five general circulation models with biogeochemistry. journal of geophysical research* oceans 117, c00d12, doi 10.1029/2011jc007112. raymond p.a., mcclelland j.w., holmes r.m., zhulidov a.v., mull k., peterson b.j., striegl r.g., aiken g.r. & gurtovaya t.y. 2007. flux and age of dissolved organic carbon exported to the arctic ocean: a carbon isotopic study of the five largest arctic rivers. global biogeochemical cycles 21, gb4011, doi: 10.1029/2007gb002934. reilly s.b., bannister j.l., best p.b., brown m., brownell r.l. jr., butterworth d.s., clapham p.j., cooke j., donovan g.p., urbán j. & zerbini a.n. 2008a. balaenoptera acutorostrata. in: iucn red list of threatened species. version 2014.1. accessed on the internet at www.iucnredlist.org on 3 july 2014 reilly s.b., bannister j.l., best p.b., brown m. brownell r.l. jr., butterworth d.s., clapham p.j., cooke j., donovan g.p., urbán j. & zerbini a.n. 2008b. eschrichtius robustus. in: iucn red list of threatened species. version 2014.1. accessed on the internet on www.iucnredlist.org on 3 july 2014 reilly s.b., bannister j.l., best p.b., brown m., brownell r.l. jr., butterworth d.s., clapham p.j., cooke j., donovan g.p., urbán j. & zerbini a.n. 2012. balaena mysticetus. in: iucn red list of threatened species. version 2014.1. accessed on the internet on www.iucnredlist.org 3 july 2014 renaud p.e., berge j., varpe ø., lønne o.j., nahrgang j., ottesen c. & hallanger i. 2012. is the poleward expansion status and trends in the structure of arctic benthic food webs m. kędra et al. 20 (page number not for citation purpose) citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 http://www.iucnredlist.org http://www.iucnredlist.org http://www.iucnredlist.org http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 by atlantic cod and haddock threatening native polar cod, boreogadus saida? polar biology 35, 401�412. renaud p.e., carroll m.l. & ambrose w.g. jr. 2008. effects of global warming on arctic sea-floor communities and its consequences for higher trophic levels. in c.m. duarte (ed.): impacts of global warming on polar ecosystems. pp. 139� 175. bilbao: fundación bbva. renaud p.e., morata n., ambrose w.g. jr., bowie j.j. & chiuchiolo a. 2007. carbon cycling by seafloor communities on the eastern beaufort sea shelf. journal of experimental marine biology and ecology 349, 248�260. renaud p.e., morata n., carroll c.l., denisenko s.g. & reigstad m. 2008. pelagic�benthic coupling in the western barents sea: processes and time scales. deep-sea research part ii 55, 2372�2380. renaud p.e., tessmann m., evenset a. & christensen g.n. 2011. benthic food-web structure of an arctic fjord (kongsfjorden, svalbard). marine biology research 7, 13�26. rich j., gosselin m., sherr e., sherr b. & kirchman d.l. 1997. high bacterial production, uptake and concentrations of dissolved organic matter in the central arctic ocean. deepsea research part ii 44, 1645�1663. rosen d.a.s. & trites a.w. 2000. pollock and the decline of steller sea lions: testing the junk-food hypothesis. canadian journal of fisheries and aquatic sciences 78, 1243�1250. rubao j., meibing j. & varpe o. 2013. sea ice phenology and timing of primary production pulses in the arctic ocean. global change biology 19, 734�741. rysgaard s., kuhl m., glud r.n. & hansen j.w. 2001. biomass, production and horizontal patchiness of sea ice algae in a high-arctic fjord (young sound, ne greenland). marine ecology progress series 223, 15�26. sakshaug e. 2004. primary and secondary production in the arctic seas. in r. stein & r.w. macdonald (eds.): the organic carbon cycle in the arctic ocean. pp. 57�81. new york: springer. sakshaug e., johnsen g., kristiansen s., von quillfeldt c., rey f., slagstad d. & thingstad f. 2009. phytoplankton and primary production. in e. sakshaug et al. (eds.): ecosystem barents sea. pp. 167�208. trondheim: tapir academic press. sarmento h., montoya j.m., vazquez-dominquez e., vague d. & gasol j.m. 2010. warming effects on marine microbial food web processes: how far can we go when it comes to predictions? philosophical transactions of the royal society of london b 365, 2137�2149. scott c.l., falk-petersen s., gulliksen b., lønne o.j. & sargent j.r. 2001. lipid indicators of the diet of gammarus wilkitzkii in the marginal ice zone and in open waters of svalbard. polar biology 24, 575�576. scott c.l., falk-petersen s., sargent j.r., hop h., lønne o.j. & poltermann m. 1999. lipids and trophic interactions of ice fauna and pelagic zooplankton in the marginal ice zone of the barents sea. polar biology 21, 65�70. screen j.a. & simmonds i. 2010. the central role of diminishing sea ice in recent arctic temperature amplification. nature 464, 1334�1337. serreze m.c., barret a.p., stroeve j., kindig d.n. & holland m.m. 2009. the emergence of surface-based arctic amplification. the cryosphere 3, 11�19. sherr e.b., sherr b.f. & hartz a.j. 2009. microzooplankton grazing impact in the western arctic ocean. deep-sea research part ii 56, 1264�1273. shiklomanov a.i. & lammers r.b. 2009. record russian river discharge in 2007 and the limits of analysis. environmental research letters 4, 045015, doi: 10.1088/1748-9326/4/4/ 045015. shimada k., kamoshida t., itoh m., nishino s., carmack e., mclaughlin f., zimmermann s. & proshutinsky a. 2006. pacific ocean inflow: influence on catastrophic reduction of sea ice cover in the arctic ocean. geophysical research letters 33, l08605, doi: 10.1029/2005gl025624. sirenko b.i. & gagaev s.y. 2007. unusual abundance of macrobenthos and biological invasions in the chukchi sea. russian journal of marine biology 33, 355�364. sirenko b.i. & kolutin v.m. 1992. characteristics of benthic biocenoses of the chukchi and bering seas. in p.a. nagel (ed.): results of the third joint us�ussr bering & chukchi seas expedition (berpac), summer 1988. pp. 251�258. washington, dc: us fish and wildlife service. slagstad d., ellingsen i.h. & wassmann p. 2011. evaluating primary and secondary production in an arctic ocean void of summer sea ice: an experimental simulation approach. progress in oceanography 90, 117�131. soltwedel t., bauerfeind e., bergmann m., budaeva n., hoste e., jaeckisch n., von juterzenka k., matthiessen j., mokievsky v., nöthig e.m., quéric n.v., sablotny b., sauter e., schewe i., urban-malinga b., wegner j., włodarska-kowalczuk m. & klages m. 2005. hausgarten* multidisciplinary investigations at a deep-sea long-term observatory in the arctic ocean. oceanography 18, 46�61. søreide j.e., hop h., carroll m.l., falk-petersen s. & hegseth e.n. 2006. seasonal food web structures and sympagic� pelagic coupling in the european arctic revealed by stable isotopes and a twosource food web model. progress in oceanography 71, 59�87. søreide j.e., leu e., berge j., graeve m. & falk-petersen s. 2010. timing of blooms, algal food quality and calanus glacialis reproduction and growth in a changing arctic. global change biology 16, 3154�3163. springer a.m., mcroy c.p. & flint m.v. 1996. the bering sea green belt: shelf-edge processes and ecosystem production. fisheries oceanography 5, 205�223. squire v.a. 2007. of ocean waves and sea-ice revisited. cold regions science and technology 49, 110�133. squire v.a., dugan j.p., wadhams p., rottier p.j. & liu a.k. 1995. of ocean waves and sea ice. annual review of fluid mechanics 27, 115�168. steele m., ermold w. & zhang j.l. 2008. arctic ocean surface warming trends over the past 100 years. geophysical research letters 35, l02614, doi: 10.1029/2007gl031651. stocker t.f., qin d., plattner g.-k., tignor m., allen s.k., boschung j., nauels a., xia y., bex v. & midgley p.m. (eds.): 2013. climate change 2013. the physical science basis. contribution m. kędra et al. status and trends in the structure of arctic benthic food webs citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 21 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 of working group i to the fifth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. strong c. & rigor i.g. 2013. arctic marginal ice zone trending wider in summer and narrower in winter. geophysical research letters 40, 4864�4868. sturluson m., gissel nielsen t. & wassmann p. 2008. bacterial abundance, biomass and production during spring blooms in the northern barents sea. deep-sea research part ii 55, 2186�2198. symon c., arris l. & heal b. 2005. arctic climate impact assessment. cambridge: cambridge university press. tamelander t., reigstad m., hop h., carroll m.l. & wassmann p. 2008. pelagic and sympagic contribution of organic matter to zooplankton and vertical export in the barents sea marginal ice zone. deep-sea research part ii 55, 2330�2339. tamelander t., renaud p.e., hop h., carroll m.l., ambrose w.g. jr. & hobson k.a. 2006. trophic relationships and pelagic�benthic coupling during summer in the barents sea marginal ice zone, revealed by stable carbon and nitrogen isotope measurements. marine ecology progress series 310, 33�46. timmermans m.l. & winsor p. 2013. scales of horizontal density structure in the chukchi sea surface layer. continental shelf research 52, 39�46. tremblay j.e., simpson k., martin j., miller l., gratton y., barber d. & price n.m. 2008. vertical stability and the annual dynamics of nutrients and chlorophyll fluorescence in the coastal, southeast beaufort sea. journal of geophysical research*oceans 113, c07s90, doi: 10.1029/2007jc004547. trites a.w., livingston p.a., vasconcellos m.c., mackinson s., springer a.m. & pauly d. 1999. ecosystem considerations and the limitations of ecosystem models in fisheries management: insights from the bering sea. ecosystem approaches for fisheries management, alaska sea grant college program, report 99�01. fairbanks: university of alaska sea grant. vander zanden m.j., casselman j.m. & rasmussen j.b. 1999. stable isotope evidence for the web consequences of species invasions in lakes. nature 401, 464�467. van oevelen d., bergmann m., soetaert k., bauerfeind e., hasemann c., klages m., schewe i., soltwedel t. & budaeva n. 2011. carbon flows in the benthic food web at the deepsea observatory hausgarten (fram strait). deep-sea research part i 58, 1069�1083. van oevelen d., van den meersche k., meysman f.j.r., soetaert k., middleburg j.j. & vézina a.f. 2010. quantifying food web flows using linear inverse models. ecosystems 13, 32�45. vanreusel a., clough l.m., jacobsen k., ambrose w.g. jr., jivaluk j., ryheul v., herman r. & vincx m. 2000. meiobenthos of the central arctic ocean with special emphasis on the nematode community structure. deep-sea research part i 47, 1855�1879. vaquer-sunyer r., duarte c.m., santiago r., wassmann p. & reigstad m. 2010. experimental evaluation of planktonic respiration response to warming in the european arctic sector. polar biology 33, 1661�1671. varpe o. 2012. fitness and phenology: annual routines and zooplankton adaptations to seasonal cycles. journal of plankton research 34, 267�276. wadhams p. 2000. ice in the ocean. amsterdam: gordon & breach science publishers. wadhams p., squire v.a., goodman d.j., cowan a.m. & moore s.c. 1988. the attenuation rates of ocean waves in the marginal ice zone. journal of geophysical research 93, 6799�6818. walczowski w. & piechura j. 2006. new evidence of warming propagating toward the arctic ocean. geophysical research letters 33, l12601, doi: 10.1029/2006gl025872. walczowski w., piechura j., goszczko i. & wieczorek p. 2012. changes in atlantic water properties: an important factor in the european arctic marine climate. ices journal of marine science 69, 864�869. walsh j.j., mcroy c.p., coachman l.k., goering j.j., nihoul j.j., whitledge t.e., blackbum t.h., parker p.l., wirick c.d., shuert p.g., grebmeier j.m., springer a.m., tripp r.d., hansell d.a., djenidi s., deleersnijder e., henriksen k., lund b.a., andersen p., muller-karger f.e. & dean k. 1989. carbon and nitrogen cycling within the bering/chukchi seas: source regions of organic matter affecting aou demands of the arctic ocean. progress in oceanography 22, 279�361. walther g.r., post e., convey p., menzel a., parmesank c., beebee t.j.c., fromentin j.m., hoegh-guldberg o. & bairlein f. 2002. ecological responses to recent climate change. nature 416, 389�395. wanless s., harris m., redman p. & speakman j. 2005. low energy values of fish as a probable cause of a major seabird breeding failure in the north sea. marine ecology progress series 294, 1�8. wassmann p. 2006. structure and function of contemporary food webs on arctic shelves: an introduction. progress in oceanography 71, 123�128. wassmann p., carroll j. & bellerby r.g.j. 2008. carbon flux and ecosystem feedback in the northern barents sea in an era of climate change: an introduction. deep-sea research part ii 55, 2143�2153. wassmann p., duarte c.m., agusti s. & sejr m.k. 2011. footprints of climate change in the arctic marine ecosystem. global change biology 17, 1235�1249. wassmann p. & reigstad m. 2011. future arctic ocean seasonal ice zones and implications for pelagic�benthic coupling. oceanography 24, 220�231. wassmann p., reigstad m., haug t., rudels b., carroll m.l., hop h., gabrielsen g.w., falk-petersen s., denisenko s.g., arashkevich e., slagstad d. & pavlova o. 2006. food webs and carbon flux in the barents sea. progress in oceanography 71, 232�287. wassmann p., slagstad d. & ellingsen i. 2010. primary production and climatic variability in the european sector of the arctic ocean prior to 2007: preliminary results. polar biology 33, 1641�1650. wassmann p., slagstad d., riser c.w. & reigstad m. 2006. modelling the ecosystem dynamics of the barents sea status and trends in the structure of arctic benthic food webs m. kędra et al. 22 (page number not for citation purpose) citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 including the marginal ice zone: ii. carbon flux and interannual variability. journal of marine systems 59, 1�24. weeks w.f. 2010. on sea ice. fairbanks, ak: university of alaska press. wells l.e. & deming j.w. 2006. modelled and measured dynamics of viruses in arctic winter sea-ice brines. environmental microbiology 8, 1115�1121. werner i. & auel h. 2005. seasonal variability in abundance, respiration and lipid composition of arctic under-ice amphipods. marine ecology progress series 292, 251�262. werner i., auel h. & friedrich c. 2002. carnivorous feeding and respiration of the arctic under-ice amphipod gammarus wilkitzkii. polar biology 25, 523�530. węslawski j.m., kwaśniewski s. & stempniewicz l. 2009. warming in the arctic may result in the negative effects of increased biodiversity. polarforschung 78, 105�108. wheeler p.a., watkins j.m. & hansing r.l. 1997. nutrients, organic carbon and nitrogen in the upper water column of the arctic ocean: implications for the sources of dissolved organic carbon. deep-sea research part ii 44, 1571�1592. whitehouse g.a., aydin k., essington t.e. & hunt g.l. jr. 2014. a trophic mass balance model of the eastern chukchi sea with comparisons to other high-latitude systems. polar biology 37, 911�939. wienerroither r.m., nedreaas k., uiblein f., christiansen j.s., byrkjedal i. & karamushko o. 2011. the marine fishes of jan mayen island, ne atlantic*past and present. marine biodiversity 41, 395�411. wilson w.h., tarran g.a., schroeder d., cox m.j., oke j. & malin g. 2002. isolation of viruses responsible for the demise of an emiliania huxleyi bloom in the english channel. journal of the marine biological association of the united kingdom 82, 369�377. woodgate r.a., aagaard k. & weingartner t. 2006. interannual changes in the bering strait fluxes of volume, heat and freshwater between 1991 and 2004. geophysical research letters 33, l15609, doi: 10.1029/2006gl026931. woodgate r.a., weingartner t. & lindsay r. 2010. the 2007 bering strait oceanic heat flux and anomalous arctic sea-ice retreat. geophysical research letters 37, l01602, doi: 10.1029/ 2009gl041621. woodgate r.a., weingartner t. & lindsay r. 2012. observed increases in bering strait oceanic fluxes from the pacific to the arctic from 2001 to 2011 and their impacts on the arctic ocean water column. geophysical research letters 39, l24603, doi: 10.1029/2012gl054092. zhang j., spitz y.h., steele m., ashijian c., campbell r., beline l. & matrai p. 2010. modeling the impact of declining sea ice on the arctic marine planktonic ecosystem. journal of geophysical research*oceans 115, c10015, doi: 10.1029/ 2009jc005387. m. kędra et al. status and trends in the structure of arctic benthic food webs citation: polar research 2015, 34, 23775, http://dx.doi.org/10.3402/polar.v34.23775 23 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23775 http://dx.doi.org/10.3402/polar.v34.23775 doi:10.3402/polar.v35.28269 r e s e a r c h / r e v i e w a r t i c l e tilt signals at mount melbourne, antarctica: evidence of a shallow volcanic source salvatore gambino, marco aloisi, giuseppe falzone & angelo ferro catania department, national institute of geophysics and volcanology, piazza roma 2, it-95123 catania, italy keywords tilt monitoring; volcanic dynamics; physics volcanology; ground deformation; victoria land. correspondence salvatore gambino, catania department, national institute of geophysics and volcanology, piazza roma 2, it-95123 catania, italy. e-mail: salvatore.gambino@ ingv.it abstract mount melbourne (74821? s, 164843? e) is a quiescent volcano located in northern victoria land, antarctica. tilt signals have been recorded on mount melbourne since early 1989 by a permanent shallow borehole tiltmeter network comprising five stations. an overall picture of tilt, air and permafrost temperatures over 15 years of continuous recording data is reported. we focused our observations on long-term tilt trends that at the end of 1997 showed coherent changes at the three highest altitude stations, suggesting the presence of a ground deformation source whose effects are restricted to the summit area of mount melbourne. we inverted these data using a finite spherical body source, thereby obtaining a shallow deflation volume source located under the summit area. the ground deformation observed corroborates the hypothesis that the volcanic edifice of mount melbourne is active and should be monitored multidisciplinarily. to access the supplementary material for this article, please see the supplementary files under article tools, online. ground deformation studies of volcanoes are fundamental for forecasting eruptions and better understanding magmatic processes (dzurisin 2003). spatial and temporal (shortand long-term) patterns of ground deformation are detected by using different techniques such insar, gps, tiltmeters, strainmeters, edm and levelling and results are usually related to changes in the volume and location of magma. especially at volcanoes with steam vents, ground deformation can also originate from movements of geothermal fluids, where the fluid dynamic may be caused by heating of the geothermal reservoir (e.g., nakaboh et al. 2003; battaglia et al. 2006). the frequent occurrence of long-term ground deformation (months�years), in open and closed volcanic systems, has recently been shown using satellite techniques (e.g., chaussard et al. 2013; henderson & pritchard 2013), levelling (e.g., murase et al. 2014), edm (battaglia et al. 2006) and, more rarely, tilt (bonaccorso et al. 2015). shallow borehole tiltmeters are used to monitor the ground deformation of volcanoes throughout the world since they are able to measure precise tilt variations (dzurisin 1992, 2003; ferro et al. 2011). these changes range from slow (months�years) to fast (minutes�days), highlighting different processes occurring at volcanoes (gambino et al. 2014). in particular, slow variations indicate the inflation/deflation of the edifice caused by volume changes in magma reservoirs (e.g., de zeeuw-van dalfsen et al. 2005) or movements of geothermal fluids (e.g., nakaboh et al. 2003). tilt measurements have revealed, in different monitored volcanic areas, middle and long-term ground deformation related to edifice inflation/deflation, such as at piton de la fournaise (fontaine et al. 2014), mount etna (bonaccorso et al. 2004), stromboli (bonaccorso et al. 2008; bonaccorso et al. 2009), vulcano (gambino et al. 2007) and vesuvius (ricco et al. 2013). located in northern victoria land, mount melbourne (2732 m a.s.l.) is a large stratovolcano (fig. 1a) belonging to the mcmurdo volcanic group (kyle 1989) and is one of the closed conduit volcanoes in antarctica with the potential for large-scale explosive eruptions. physical volcanological studies aimed at studying mount melbourne’s polar research 2016. # 2016 s. gambino et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 28269, http://dx.doi.org/10.3402/polar.v35.28269 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/28269/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/28269/0 http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/28269 http://dx.doi.org/10.3402/polar.v35.28269 internal dynamics began in 1988 within the framework of the italian antarctic research programme. a tilt network of five permanent continuously recording stations was installed in 1988�89 (figs. 1b, 2) and a seismic network in 1990 (bonaccorso et al. 1996; bonaccorso, gambino, falzone et al. 1997). gambino & privitera (1996) identified and characterized local seismicity at mount melbourne. several seismic analyses, performed on a data set of 17 micro-earthquakes, suggested these events were either ‘‘long-period events’’ (e.g., chouet 1992), indicating the active presence of fluids in source processes, or were linked to fracturing processes in a medium in transition between the brittle and plastic states (gambino & privitera 1996). on the whole, seismic and tilt data indicate that mount melbourne is a quiescent volcano with its own slow, but continual, internal dynamics (bonaccorso et al. 1995; bonaccorso, gambino & privitera 1997). here we report observations and analyses of 15 years of continuous ground tilt collected at mount melbourne that highlight changes and suggest a possible internal volcanic source. mount melbourne volcano mount melbourne is a volcanic edifice situated between terra nova and wood bays in northern victoria land, with a summit caldera of about 1 km in diameter and characterized by fumarolic activity (nathan & schulte 1967; keys et al. 1983; kyle 1989; wörner & viereck 1989). mount melbourne is one of the stratovolcanoes in the mcmurdo volcanic group, which has developed along the western margin of the ross sea in victoria land, and parallel to the transantarctic mountains (kyle 1989). this area (fig. 1a) was recently affected by distensive tectonics on the north-west�south-east structural system forming the rennick graben to the north and on the nne�sse system to the south, evidenced by the nansen graben (skinner 1983; carmignani et al. 1989; lanzafame & villari 1991). the volcanic field seems to have formed at the intersection of these systems and the development of the volcanic activity is generally related to the apparent discontinuity of the two structural systems (lanzafame & villari 1991). volcanism in the mount melbourne area started during the upper pliocene with the formation of the cape washington shield volcano. during the lower and middle pleistocene, volcanism migrated towards the transantarctic mountains, while in the upper pleistocene/holocene the mount melbourne stratovolcano was associated with the establishment of a crustal magma chamber (giordano et al. 2012). the volcanic activity at mount melbourne is testified by blankets of pyroclastic pumice and scoria fall abbreviations in this article edm: electronic distance measurements ga: genetic algorithm gps: global positioning system insar: interferometric synthetic aperture radar ps: pattern search vlndef: victoria land network for deformation control 165°164° 300 800 1 0 0 0 400 380 1400 4 0 0 terra nova bay shield nunatak m. zucchelli italian base wood bay 600 willows nunatak baker rocks cape washington 680 273 edmonson point miller nunatak c m p e a b ll g la cie r tongue fal1 vil 5 km mt. melbourne tilt station vl06 gps benchmark fumaroles vil1 cont fal 100 km –73° –72° –74°15' –74°30'–74° –75° 170°165° mt. nansen n an se n g ra be n t ra n sa n ta rc tic m ou nt ai ns admiralty mts. r os s s ea mt. overlord mt. rittmann tectonic lines main tectonic lines r e n n ick g ra b e n malta plateau c. adare c. hallet culman i. mt. melbourne northern victoria land antarctica 70° 80° eastwest (a) (b) fig. 1 tectonic sketch map of (a) northern victoria land (redrawn from carmignani et al. 1989). (b) map of the permanent tilt network on mount melbourne. tilt signals at mount melbourne s. gambino et al. 2 (page number not for citation purpose) citation: polar research 2016, 35, 28269, http://dx.doi.org/10.3402/polar.v35.28269 http://www.polarresearch.net/index.php/polar/article/view/28269 http://dx.doi.org/10.3402/polar.v35.28269 around the eastern and southern flanks (wörner & viereck 1989), by pyroclastic layers interbedded with the summit snows (nathan & schulte 1967; keys et al. 1983) and by the moderate fumarolic activity (598c at 25 cm depth) in the summit area (lyon & giggenbach, 1974; keys et al. 1983; cremisini et al. 1991). the most recent activity is believed to date back no further than 200 years (adamson & cavaney 1967; nathan & schulte 1967; keys et al. 1983). on the basis of the depth at which tephra layers from the most recent explosive activity at mount melbourne were found within the ice cap, lyon (1986) proposed that the most recent eruption probably occurred between 1862 and 1922. the tilt network in early 1989, five continuous recording sensors (figs. 1b, 2; supplementary fig. s1) consisting of biaxial borehole bubble sensors were installed at a depth of about 2.5 m (bonaccorso et al. 1995). the tilt sensors have a 0.1 microradian resolution (applied geomechanics model 722) and two components trend radially (tilt x) and tangentially (tilt y) with respect to the mount melbourne summit. in particular, increases in the radial component indicate inflation of the crater area, while positive variations of the tangential component indicate inflation at 908 counter-clockwise with respect the radial component. the boreholes also have two thermocouples (t1, t2) (copper� constantan type, 0.18c precision) shaft (mean depths 1.0 and 1.9 m, respectively) and a tilt temperature sensor at the ends of the instrument that records the permafrost temperature. the control data-logger was programmed for 48 data/day sampling (one sample every 30 min) and includes acquisition of the two tilt components, air (tbox) and ground temperatures and instrumental control parameters, such as battery and dc/dc voltage. each station is equipped with solid state memories which guarantee data acquisition through the winter months, while high capacity batteries power the station. data the tilt network data set spans the beginning of 1989 to the end of 2003. partial interruptions were caused by data-logger auto-protection, which activates under a voltage threshold of about 10v, or by electronic malfunctioning, which is to be expected under �358c. some interruptions took place when the external temperature oscillations began to wane and there was no longer sunlight. data acquisition ended in 2003 with reduction in personnel stationed in antarctica. air and ground temperatures the permanent tilt network has allowed the continuous recording of air and permafrost temperature. some features of temperature data are shown in fig. 3, which presents one month of signals at different depths; summer daily fluctuations were attenuated with depth ranging from over 10�158c at the surface (tbox), to about 2�48c at �0.5 m (t1), to 1�28c at �1.5 m (t2) and down to quartz sand tiltmeter body with internal electonics tilt sensor and t 3 data logger rx t x battery thermocouple 2 .5 m e tr e s tilt components direction (+y + = up) (+x + = up) t 1 t 2 0 .8 8 m fig. 2 scheme of a borehole tiltmeter. –20 –15 –10 –5 0 5 10 1/1/91 6/1/91 11/1/91 16/1/91 21/1/91 26/1/91 31/1/91 t box d e g re e s °c t 1 t 2 t 3 fig. 3 example of daily cycle recorded at the four temperature sensors of the cont station in january 1991 (redrawn from gambino 2005). s. gambino et al. tilt signals at mount melbourne citation: polar research 2016, 35, 28269, http://dx.doi.org/10.3402/polar.v35.28269 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/28269/0 http://www.polarresearch.net/index.php/polar/article/view/28269 http://dx.doi.org/10.3402/polar.v35.28269 approximately zero at the deeper sensor (t3 at �2.5 m). seasonal temperature changes at mount melbourne are marked. air temperature changes exceeded 308c at all the stations while ground temperature changes decrease with depth (fig. 4; bonaccorso et al. 1995). t3 at the highest station (vil, 2030 m a.s.l.) showed mean daily permafrost temperature between �18 and �338c, while for the lower altitude station (fal1, 800 m a.s.l.) the range was between �9 and �228c. an analysis of t3 permafrost temperatures recorded at vil, cont, fal1 and vil1 stations between 1989 and 1998, performed by gambino (2005), highlighted a negative trend for all stations and indicate a cooling of this area in accordance with climatic studies of northern victoria land (e.g., kwok & comiso 2002). tilt signals shallow borehole tilt data are generally affected by diurnal and seasonal noise linked to temperature effects (e.g., bonaccorso et al. 1999). at mount melbourne, diurnal fluctuations were observed only during the antarctic summer and were in the range of 2�12 microradians (bonaccorso et al. 1995); for long-term analysis we applied a moving average of 96 samples (two days) in order to remove the daily high frequency noise. the obtained tilt signals are shown in figs. 5 and 6; signals show seasonal fluctuations that range between 10 and 20 microradians. although the signals are affected by annual variations due to the seasonal temperature changes, the long-term is easily identified and a filtering of these effects is not necessary. long-term trends recorded in tilt data comprise real ground deformation, the local site dynamic and instrumental drift (e.g., kohl & levine 1993; anderson et al. 2010). the secular marked trends visible at vil and to a lesser degree at cont (figs. 5, 6, phase 2) stations may be linked to instrumental drifts. a general picture of mount melbourne tilt signals (figs. 5, 6) evidenced two or three phases for almost each signal. in particular, a first phase (1), lasting about one year, was present on almost all signals and was dominated by instrument/site stabilization effects after installation (agi 1993). successively, from 1990 to the end of 1997, tilt trends (phase 2) were constant, while at the end of 1997 and the beginning of 1998 the radial components of the three summit stations (vil, fal, vil1) showed a lowering of their trends almost contemporaneously (phase 3). we have estimated these changes, in comparison to the stable 1990�97 period, at �3.0, �4.2 and �5.5 microradians/year, respectively, for vil, fal and vil1 stations (fig. 5). –40 –30 –20 –10 0 10 01/01/1989 28/09/1991 24/06/1994 20/03/1997 15/12/1999 10/09/2002 t1 t2 t3 t box d eg re es c ° fig. 4 air and permafrost temperatures historical series recorded at the fal1 station. data have been filtered by applying a moving average of 96 samples, to remove the summer daily frequency, and successively resampled for each day. 10 microradians 01/1988 09/1990 06/1993 03/1996 12/1998 09/2001 06/2004 vil1 x fal x fal1 x cont x vil x 1 1 1 1 1 2 3 3 3 2 2 2 2 3.0 microradians/yr 4.2 microradians/yr 5.5 microradians/yr fig. 5 radial tilt component at the five stations. data filtered to remove the high frequency noise by applying a moving average of 96 samples (two days). numbers define the three phases discussed in detail in the text. tilt signals at mount melbourne s. gambino et al. 4 (page number not for citation purpose) citation: polar research 2016, 35, 28269, http://dx.doi.org/10.3402/polar.v35.28269 http://www.polarresearch.net/index.php/polar/article/view/28269 http://dx.doi.org/10.3402/polar.v35.28269 global positioning system gps measurements at the mount melbourne area have been performed since 1990�91, when a geodetic gps network was established to monitor the deformation of the volcano (capra et al. 1998). the network, made up of 12 benchmarks, has been surveyed four times: 1990�91, 1993�94, 1995 and 1997�98 by gps methodology in static modality. the results obtained with different software and different approaches gave significantly different results (capra et al. 1998). the development of modern space geodesy techniques and requests made by the scientific community to extend the area investigated by gps observations led to deploying a new network of 32 benchmarks (vlndef) covering the entire northern victoria land area (dubbini et al. 2010) designed for geodynamic purposes. this network includes the vl06 benchmark (fig. 1b) positioned on the summit area of mount melbourne; during 1999�2003 vl06 showed no significant movements (capra et al. 2007). in the successive period (until 2006), vl06 showed an uplift of 6.14 (91.62) mm/year without horizontal changes (dubbini et al. 2010). the vlndef processed gps data are the results of the primary role of the tectonics acting on northern victoria land (dubbini et al. 2010). modelling we inverted the tilt data in order to image the observed deformation pattern under the conditions of a homogeneous, isotropic and elastic half-space. we considered the estimated changes at vil, vil1 and fal, assigning no changes to fal and cont stations. a pressure source was modelled using the finite spherical body solution of mctigue (1987), obtaining a plausible data fit (fig. 7). we chose this source model since, in this case, it has a good trade-off between the number of degrees of freedom and the obtained data fit. it is worth noting that we have few available recorded data (five tiltmeters and one gps station) and it is not possible to use a more complex pressure source. the mctigue pressure source is determined by five parameters: the coordinates ‘‘xc,’’ ‘‘yc,’’ and ‘‘zc’’ of the sphere centre, the radius ‘‘a’’ and the pressure ‘‘p’’ on the surface of the model. the volume variation dv was calculated as dv �pa3p/m, according to tiampo et al. (2000), using a suitable rigidity modulus m for volcanic region of 5 gpa (e.g., bonafede et al. 1986; davis 1986; newman et al. 2006). the effects of the topography were included using the varying-depth model of williams & wadge (1998), which assumes a different elevation for each recording station corresponding to the actual elevation of the benchmark. as said before, the medium was assumed homogeneous and isotropic with a young modulus of 75 gpa and a poisson ratio of 0.25 chosen as typical values for volcanic region. to estimate the model parameters, we performed an analytical inversion using an optimization approach based on the use of gas (goldberg 1989). gas implement strategies based on the simulation of natural laws, in the evolutionistic sense. using probabilistic transition rules during iterations, gas search for the best value of the ‘‘fitness’’ function to be optimized starting from a ‘‘population’’ of points belonging to the function domain and not from a single one. in this way, the probability of finding local minima is reduced. subsequently, to better refine the previously solution, we applied the ps technique 20 microradians vil1 y cont y fal1 y fal y vil y 1 1 1 1 1 2 2 2 2 2 01/1988 09/1990 06/1993 03/1996 12/1998 09/2001 06/2004 fig. 6 tangential tilt component at the five stations. data filtered to remove the high frequency noise by applying a moving average of 96 samples (two days). numbers define the three phases discussed in detail in the text. s. gambino et al. tilt signals at mount melbourne citation: polar research 2016, 35, 28269, http://dx.doi.org/10.3402/polar.v35.28269 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/28269 http://dx.doi.org/10.3402/polar.v35.28269 (lewis & torczon 1999; lewis et al. 2000) and the nonlinear least squares method (kelley 1999). ps methods are a class of direct search methods for solving nonlinear optimization problems. these methods are characterized by a series of exploratory moves that consider the behaviour of the objective function at a pattern of points, all of which lie on a rational lattice. the exploratory moves consist of a systematic strategy for visiting the points in the lattice in the immediate vicinity of the current iterate. moreover, the nonlinear least squares method, applied in this study to the solution found by the ps method, is the form of least squares analysis used to fit a set of m observations with a model that is non-linear in n unknown parameters. the method approximates the model by a linear one and refines the n parameters by successive iterations. to estimate the uncertainty of each optimized model parameter, a jackknife resampling method (efron 1982) was adopted. this technique requires several optimizations. first, we estimate the solution by using all available data, dn, composed of n data. then, by removing one input measurement at a time, we estimate a new solution using the data dn �1,i, where the subscript indicates the size of the data set and the index of the removed measurement. then, the new solution estimator is derived as: d�n ¼ ndn �ðn � 1þdn�1; where dn�1 ¼ pn i¼1 dn�1;i n variance is estimated using the following formula. r2j ¼ n � 1 n xn�1 i¼1 ðdn�1;i � dn�1þ 2 some quantitative examples of application of these methods can be found in work by fernàndez et al. (2001), tiampo et al. (2004), aloisi et al. (2009) and patanè et al. (2013). the final optimal solution is shown in fig. 7 and table 1. in table 1, we report the misfit between the observed and modelled data as the value of the weighted root mean square error: wrmse ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi x i¼up di � dcið þ 2 ei v u u t ; where di is the measured variation with an error oi at the i-th benchmark (0.5 microradians for tilt observations 0.005 m for horizontal displacements, 0.02 m for vertical displacements) and dci is the respective modelled value. the used errors oi are typical measurement uncertainties. we obtained a deflating source at a depth of about �0.8 km (a.s.l.) with an uncertainty of about 90.6 km. regarding the modelled variation in volume (table 1), we estimated a value of about �2.1 (9 1.7) 106 m3. discussion and conclusions long-term trends recorded on tiltmeters are a combination of real ground tilt (tectonic, volcanic), local and installation instability and instrumental drift. during the 1990�97 period, tilt data on mount melbourne indicate a stable period in which tilt trends do not change. this state changed in the 1998�2002 interval when radial components of the three summit stations show a lowering of their trends. the fact that long period trends altered at about the same time on different instruments after 800 1400 2000 5 km mt.melbourne summit (2732 m) r o ss s e a –1000 –500 0 500 1000 1500 2000 2500 3000 a a a’ a’a’ tilt station fal fal1 cont recorded tilt vector modelled tilt vector vil1 vil fig. 7 location and east�west cross-section of the pressure source modelled. the vertical error is reported on the cross section. tilt signals at mount melbourne s. gambino et al. 6 (page number not for citation purpose) citation: polar research 2016, 35, 28269, http://dx.doi.org/10.3402/polar.v35.28269 http://www.polarresearch.net/index.php/polar/article/view/28269 http://dx.doi.org/10.3402/polar.v35.28269 7�8 years of stability suggests that a new ground deformation source was active after the end of 1997. these changes are a coherent indication of a general deflation and contraction of the mount melbourne edifice during 1998�2002. we sought to obtain a model for these deformations and an optimal solution (fig. 7, table 1) shows a deflation source ca. 1.0�2.2 km deep with respect to mount melbourne’s summit caldera (2400 m a.s.l.). modelling employed tilt data but we also considered the possibility of introducing discrete gps measurements at vl06; even if vl06 did not show significant variations during 1999� 2003, it was successively affected by a tectonic uplift of 6.1 mm/year (dubbini et al. 2010). assuming the regional tectonic uplift as a constant, we hypothesized that between 1998 and 2002 a lowering of about 6 mm/year at mount melbourne’s summit counteracted the tectonic effects (no uplift during the 1999�2003 period). if we include data from the vl06 station during the inversion procedure, we obtain a pressure source characterized by a similar location below the summit area, compatible with model parameter uncertainties estimated using tilt data alone. it is difficult to imagine that magma may have had a role in producing this ground deformation: mount melbourne is a quiescent volcano characterized by fumarolic emanations in the caldera area and a shallow deflation source suggests a geothermal rather than a magmatic type source. long periods of deflation and contraction have been linked to shallow geothermal fluids dynamics at different volcanoes: at kuju (japan), a spherical source 600 m deep (from surface) was proposed by nakaboh et al. (2003) to explain six years of edm data; at vulcano (italy), an ellipsoidal source at ca. 400 m depth explained the 1990�96 edm and levelling data (gambino & guglielmino 2008); 2006�2013 precise levelling surveys at tatun volcano (taipei) showed deformation in relation to the hydrothermal deflation source at a depth of 2 km (murase et al. 2014). the results obtained at mount melbourne seem to be comparable with other volcanoes and point to a volume decrease linked to water/fluid removal from the upper levels of the edifice by heating of a shallow geothermal reservoir; the presence of active fluids at mount melbourne was also suggested by seismicity (gambino & privitera 1996). the data and model presented here indicate that mount melbourne is dynamic and active and bears watching for future changes in activity that may result in eruption, especially since it has been demonstrated (lyon 1986; kyle 1989) that the last eruption occurred sometime between 1862 and 1922. while eruptive activity is not likely to pose any hazard given the lack of population, infrastructure and air traffic, examination of the volcano may provide further insights into the tectonics of the region and a window into how the volcanoes of the mcmurdo group work as a contrast to the better studied, but probably more unique, mount erebus. acknowledgements we are particularly indebted to prof. letterio villari, who conceived the mt. melbourne tilt network and struggled hard to achieve it. we thank mike poland and an anonymous reviewer for their critical reading of the manuscript and constructive comments. we also thank f. cannavò for the modelling programme codes and s. conway for improving the english of this paper. references adamson r.g. & cavaney r.j. 1967. volcanic debris layers near mount melbourne, northern victoria land, antarctica. new zealand journal of geology and geophysics 10, 409�421. agi (applied geomechanics incorporation) 1993. notes on temperature coefficients and long-term drift of applied geomechanics tiltmeters. report no. a-93-1001. santa cruz, ca: applied geomechanics incorporation. aloisi m., bonaccorso a., cannavò f., gambino s., mattia m., puglisi g. & boschi e. 2009. a new dike intrusion style for the mount etna may 2008 eruption modelled through continuous tilt and gps data. terra nova 21, 316�321. anderson k., lisowski m. & segall p. 2010. cyclic ground tilt associated with the 2004�2008 eruption of mount st. helens. journal of geophysical research*solid earth 115, b11201, doi: http://dx.doi.org/10.1029/2009jb007102 battaglia m., troise c., obrizzo f., pingue f. & de natale g. 2006. evidence for fluid migration as source of deformation at campi flegrei caldera (italy). geophysical research letters 33, l01307, doi: http://dx.doi.org/10.1029/2005gl024904 bonaccorso a., bonforte a. & gambino s. 2015. twenty-five years of continuous borehole tilt and vertical displacement data at mount etna: insights on long-term volcanic dynamics. geophysical research letters 42, 10222�10229. bonaccorso a., bonforte a., gambino s., mattia m., guglielmino f., puglisi g. & boschi e. 2009. insight on recent stromboli eruption inferred from terrestrial and satellite ground table 1 best fitting range for the model. parameters source error xc (m) 490989 294 yc (m) 1748858 129 zc (m) 768 614 a (m) 129 18 p (pa) �1.6e�09 6.0e�08 dv (m3) �2.1e � 06 1.7e � 06 s. gambino et al. tilt signals at mount melbourne citation: polar research 2016, 35, 28269, http://dx.doi.org/10.3402/polar.v35.28269 7 (page number not for citation purpose) http://dx.doi.org/10.1029/2009jb007102 http://dx.doi.org/10.1029/2005gl024904 http://www.polarresearch.net/index.php/polar/article/view/28269 http://dx.doi.org/10.3402/polar.v35.28269 deformation measurements. journal of volcanology and geothermal research 182, 172�181. bonaccorso a., campisi o., falzone g. & gambino s. 2004. continuous tilt monitoring: lesson from 20 years experiences at mt. etna. in a. bonaccorso et al. (eds.): mt. etna: volcano laboratory. pp. 307�320. washington, dc: american geophysical union. bonaccorso a., falzone g. & gambino s. 1999. an investigation into shallow borehole tiltmeters. geophysical research letters 26, 1637�1640. bonaccorso a., falzone g., gambino s. & villari l. 1995. tilt signals recorded at mt melbourne volcano (northern victoria land, antarctica) between 1989�94. terra antartica 2, 111�116. bonaccorso a., gambino s., falzone g. & privitera e. 1996. physics volcanological studies in the activity framework of the mt. melbourne observatory (northern victoria land, antarctica). in a. meloni & a. morelli (eds.): italian geophysical observatories in antarctica. pp. 67�92. bologna: compositori. bonaccorso a., gambino s., falzone g. & privitera e. 1997. the volcanological observatory of mount melbourne, northern victoria land, antarctica. in c.a. ricci (ed.): the antarctic region: geological evolution and processes. pp. 1083�1086. siena: terra antartica publication. bonaccorso a., gambino s., guglielmino f., mattia m., puglisi g. & boschi e. 2008. stromboli 2007 eruption: deflation modeling to infer shallow-intermediate plumbing system. geophysical research letters 35, l06311, doi: http://dx.doi.org/ 10.1029/2007gl032921 bonaccorso a., gambino s. & privitera e. 1997. a geophysical approach to the dynamics of mt. melbourne (northern victoria land, antarctica). in c.a. ricci (ed.): the antarctic region: geological evolution and processes. pp. 531�538. siena: terra antartica publication. bonafede m., dragoni m. & quareni f. 1986. displacement and stress fields produced by a centre of dilation and by a pressure source in a viscoelastic half-space: application to the study of ground deformation and seismic activity at campi flegrei, italy. geophysical journal of the royal astronomical society 87, 455�485. capra a., mancini f. & negusini m. 2007. gps, a geodetic tool for geodynamics in northern victoria land, antarctica. antarctic science 19, 107�114. capra a., radicioni f. & vittuari l. 1998. italian geodetic network as reference frame for geodynamic purposes (terra nova bay*victoria land*antarctica). in r. forsberg et al. (eds.): geodesy on the move. pp. 498�503. berlin: springer. carmignani l., ghezzo g., gosso g., lombardo b., meccheri m., montrasio a., pertusati p.c. & salvini f. 1989. geology of the wilson terrane in the area between david and mariner glaciers, victoria land (antarctica). memorie della società geologica italiana 33, 77�97. chaussard e., amelung f. & aoki y. 2013. characterization of open and closed volcanic systems in indonesia and mexico using insar time series. journal of geophysical research* solid earth 118, 3957�3969. chouet b.a. 1992. a seismic model for the source of long period events and harmonic tremor. in p. gasparini et al. (eds.): volcanic seismology. pp. 133�156. berlin: springer. cremisini c., gianelli g., mussi m. & torcini s. 1991. geochemistry and isotope chemistry of surface waters and geothermal manifestations at terra nova bay (victoria land, antarctica). memorie della società geologica italiana 46, 463�475. davis p.m. 1986. surface deformation due to inflation of an arbitrarily oriented triaxial ellipsoidal cavity in an elastic half-space, with reference to kilauea volcano, hawaii. journal of geophysical research*solid earth and planets 91, 7429�7438. de zeeuw-van dalfsen e., rymer h., sigmundsson f. & sturkell e. 2005. net gravity decrease at askja volcano, iceland: constraints on processes responsible for continuous caldera deflation, 1988�2003. journal of volcanology and geothermal research 139, 227�239. dubbini m., cianfarra p., casula g., capra a. & salvini f. 2010. active tectonics in northern victoria land (antarctica) inferred from the integration of gps data and geologic setting. journal of geophysical research*solid earth 115, b12421, doi: http://dx.doi.org/10.1029/2009jb007123 dzurisin d. 1992. electronic tiltmeters for volcano monitoring: lessons from mount st. helens. u.s. geological survey bulletin 1966, 69�83. dzurisin d. 2003. a comprehensive approach to monitoring volcano deformation as a window on the eruption cycle. reviews of geophysics 41, article no. 1001, doi: http://dx.doi. org/10.1029/2001rg000107 efron b. 1982. the jackknife, bootstrap and other resampling plans. philadelphia: society for industrial and applied mathematics. fernàndez j., tiampo k.f., jentzsch g., charco m. & rundle j.b. 2001. inflation or deflation? new results for mayon volcano applying elastic-gravitational modelling. geophysical research letters 28, 2349�2352. ferro a., gambino s., panepinto s., falzone g., laudani g. & ducarme b. 2011. high precision tilt observation at mt. etna volcano, italy. acta geophysica 59, 618�632. fontaine f.r., roult g., michon l., barruol g. & muro a.d. 2014. the 2007 eruptions and caldera collapse of the piton de la fournaise volcano (la réunion island) from tilt analysis at a single very broadband seismic station. geophysical research letters 41, 2803�2811. gambino s. 2005. air and permafrost temperature at mt. melbourne (1989�1998). antarctic science 17, 151�152. gambino s., campisi o., falzone g., ferro a., guglielmino f., laudani g. & saraceno b. 2007. tilt measurements at vulcano island. annals of geophysics 50, 233�247. gambino s., falzone g., ferro a. & laudani g. 2014. volcanic processes detected by tiltmeters: a review of experience on sicilian volcanoes. journal volcanology geothermal research 271, 43�54. gambino s. & guglielmino f. 2008. ground deformation induced by geothermal processes: a model for la fossa crater (vulcano island, italy). journal of geophysical tilt signals at mount melbourne s. gambino et al. 8 (page number not for citation purpose) citation: polar research 2016, 35, 28269, http://dx.doi.org/10.3402/polar.v35.28269 http://dx.doi.org/10.1029/2007gl032921 http://dx.doi.org/10.1029/2007gl032921 http://dx.doi.org/10.1029/2009jb007123 http://dx.doi.org/10.1029/2001rg000107 http://dx.doi.org/10.1029/2001rg000107 http://www.polarresearch.net/index.php/polar/article/view/28269 http://dx.doi.org/10.3402/polar.v35.28269 research*solid earth 113, b07402, doi: http://dx.doi.org/10. 1029/2007jb005016 gambino s. & privitera e. 1996. mt melbourne volcano, antarctica: evidence of seismicity related to volcanic activity. pure and applied geophysics 146, 305�318. giordano g., lucci f., phillips d., cozzupoli d. & runci v. 2012. stratigraphy, geochronology and evolution of the mt. melbourne volcanic field (north victoria land, antarctica). bulletin of volcanology 74, 1985�2005. goldberg d.e. 1989. genetic algorithms in search, optimization and machine learning. boston, ma: kluwer. henderson s.t. & pritchard m.e. 2013. decadal volcanic deformation in the central andes volcanic zone revealed by insar time series. geochemistry geophysics geosystems 14, 1358�1374. kelley c.t. 1999. iterative methods for optimization. philadelphia: society for industrial and applied mathematics. keys j., mcintosh w.c. & kyle p.r. 1983. volcanic activity of mount melbourne, northern victoria land. antarctic journal of the united states 18(5), 10�11. kohl m.l. & levine j. 1993. measuring low frequency tilts. journal of research of the national institute of standards and technology 98, 191�202. kwok r. & comiso j.c. 2002. spatial patterns of variability in antarctic surface temperature: connections to the southern hemisphere annular mode and the southern oscillation. geophysical research letters 29, article no. 1705, doi: http:// dx.doi.org/10.1029/2002gl015415 kyle p.r. 1989. mcmurdo volcanic group, western ross embayment. in w.e. lemasurier & j.w. thomson (eds.): volcanoes of the antarctic plate and southern oceans. pp. 19�145. washington, dc: american geophysical union. lanzafame g. & villari l. 1991. structural evolution and volcanism in northern victoria land (antarctica): data from mt. melbourne�mt. overlord�malta plateau region. memorie della società geologica italiana 46, 371�381. lewis r.m. & torczon v. 1999. pattern search algorithms for bound constrained minimization. siam journal on optimization 9, 1082�1099. lewis r.m., torczon v. & trosset m.w. 2000. direct search methods: then and now. journal of computational and applied mathematics 124, 191�207. lyon g.l. 1986. stable isotope stratigraphy of ice cores and the age of the last eruption at mount melbourne, antarctica. new zealand journal of geology and geophysics 29, 135�138. lyon g.l. & giggenbach w.f. 1974. geothermal activity in victoria land, antarctica. new zealand journal of geology and geophysics 17, 511�521. mctigue d.f. 1987. elastic stress and deformation near a finite sphericalmagma body: resolution of the point source paradox. journal of geophysics research*solid earth 92, 12931�12940. murase m., lin c.h., kimata f., mori h. & pu h.c. 2014. volcano-hydrothermal activity detected by precise levelling surveys at the tatun volcano group in northern taiwan during 2006�2013. journal of volcanology and geothermal research 286, 30�40. nakaboh m., ono h., sako m., sudo y., hashimoto t. & hurst a.w. 2003. continuing deflation by fumaroles at kuju volcano, japan. geophysical research letters 30, article no. 1396, doi: http://dx.doi.org/10.1029/2002gl016047 nathan s. & schulte f.j. 1967. recent thermal and volcanic activity on mount melbourne, northern victoria land, antarctica. new zealand journal of geology and geophysics 10, 422�430. newman a.v., dixon t.h. & gourmelen n. 2006. a fourdimensional viscoelastic deformation model for long valley caldera, california, between 1995�2000. journal of volcanology and geothermal research 150, 244�269. patanè d., aiuppa a., aloisi m., behncke b., cannata a., coltelli m., di grazia g., gambino s., gurrieri s., mattia m. & salerno g. 2013. insights into magma and fluid transfer at mount etna by a multi-parametric approach: a model of the events leading to the 2011 eruptive cycle. journal of geophysical research*solid earth 118, 3519�3539. ricco c., aquino i., borgstrom s. & del gaudio c. 2013. 19 years of tilt data on mt. vesuvius: state of the art and future perspectives. annals of geophysics 56, article no. s0453, doi: http://dx.doi.org/10.4401/ag-6459 skinner d.n.b. 1983. the geology of terra nova bay. in r.l. oliver et al. (eds.): antarctic earth science. pp. 150�155. canberra: australian academy of science. tiampo k.f., fernandez j., gentzsch g., charco m. & rundle j.b. 2004. inverting for the parameters of a volcanic source using a genetic algorithm and a model for magmatic intrusion in elastic�gravitational layered earth models. computer and geosciences 30, 985�1001. tiampo k.f., rundle j.b., fernandez j. & langbein j.o. 2000. spherical and ellipsoidal volcanic sources at long valley caldera, california, using a genetic algorithm inversion technique. journal of volcanology and geothermal research 102, 189�206. williams c.a. & wadge g. 1998. the effects of topography on magma chamber deformation models: application to mt. etna and radar interferometry. geophysical research letters 25, 1549�1552. wörner g. & viereck l. 1989. mcmurdo volcanic group, western ross embayment (mt. melbourne). in w.e. lemasurier & j.w. thomson (eds.): volcanoes of the antarctic plate and southern oceans. pp. 72�78. washington, dc: american geophysical union. s. gambino et al. tilt signals at mount melbourne citation: polar research 2016, 35, 28269, http://dx.doi.org/10.3402/polar.v35.28269 9 (page number not for citation purpose) http://dx.doi.org/10.1029/2007jb005016 http://dx.doi.org/10.1029/2007jb005016 http://dx.doi.org/10.1029/2002gl015415 http://dx.doi.org/10.1029/2002gl015415 http://dx.doi.org/10.1029/2002gl016047 http://dx.doi.org/10.4401/ag-6459 http://www.polarresearch.net/index.php/polar/article/view/28269 http://dx.doi.org/10.3402/polar.v35.28269 local temperature near native vascular plants in the argentine islands–kyiv peninsula region, antarctic peninsula: annual variability and approximation using standard meteorological measurements research article local temperature near native vascular plants in the argentine islands–kyiv peninsula region, antarctic peninsula: annual variability and approximation using standard meteorological measurements mykhailo v. savenets,1 larysa pysarenko,1 svitlana krakovska,1,2 ivan parnikoza2,3 & denys pishniak2 1ukrainian hydrometeorological institute, kyiv, ukraine 2state institution national antarctic scientific center, kyiv, ukraine 3institute of molecular biology and genetics, national academy of sciences of ukraine, kyiv, ukraine abstract we describe the main features of lt variability that influence native vascular plants in the antarctic and examine the relationship between the temperature regime at the micro-level and meteorological conditions at the macro-level. we used a period of over a year, during which 37 specialized mini-loggers recorded lt near vascular plants in the argentine islands–kyiv peninsula region of the antarctic peninsula. rather than measuring standard air or soil temperature, these loggers detect the temperature near the ground, in the microhabitats that harbour vascular plants. on a daily scale, lt correlates with standard (2-m) air temperature, with the values higher at rock slopes than at rock terraces and ledges. a moderate correlation was found with wind and radiation parameters. seasonality accounted for 75–93% of total lt variability, with better results on open rock terraces compared to protected areas and clefts. lt day-to-day variability during the cold season is mostly responsible for differences in r2 of the annual cycle. we estimated daily mean lt using regression dependencies from 2-m air temperature and wind speed measured at a nearby meteorological station. r2 for these statistical models varies from 0.46 to 0.68. however, they underestimate the observed lt. lt measured on rock slopes showed better modelling results with air temperature, whereas wind speed was a better predictor on rock ledges. this study contributes to our understanding of the micro-scale temperature regime that influences native vascular plants and provides a method for its rough approximation using standard meteorological parameters. keywords microclimate; microhabitat; mini-logger; deschampsia antarctica; colobanthus quitensis; vegetation abbreviations lt: local temperature otc: open-top chamber   citation: polar research 2023, 42, 8339, http://dx.doi.org/10.33265/polar.v42.8339 copyright: polar research 2023. © 2023 m. savenets et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 12 may 2023 competing interests and funding: the authors report no conflict of interest. correspondence mykhailo v. savenets, ukrainian hydrometeorological institute, 03028, nauky prospekt, 37, kyiv, ukraine. e-mail: savenets@uhmi.org.ua to access the supplementary material, please visit the article landing page   introduction regardless of the distance from inhabited regions, environmental changes in antarctic terrestrial ecosystems can be good indicators for tracking anthropogenic impacts from global to local scales. this is already clearly evident in the regional climate of the maritime antarctic (turner et al. 2005; turner et al. 2013). local terrestrial biota, which exist in extremely harsh natural conditions (hogg et al. 2006; convey 2012; cannone et al. 2021), are also sensitive to global climate change (walther et al. 2002; aerts et al. 2006; convey & smith 2006), even under strong microclimatological influences (miotke 1988). the necessity for monitoring climate change impacts on vulnerable antarctic terrestrial ecosystems requires the identification of suitable meteorological parameters for analyses and estimations. observations of climate variability in the antarctic are in most cases carried out at a macro-level, using measurements of air temperature and other meteorological parameters at standard heights above the ground. these measurements are conducted at weather stations that were established to be representative of the state of the climate over a large region (wmo 2010). however, standard meteorological observations often fail to adequately describe the microclimatological conditions in which terrestrial flora, fauna and microbiota are found. understanding the relationship between meteorological parameters at microand macro-levels is crucial for studying the response to climate change of terrestrial ecosystems and their components in the region. (here, we define the micro-scale as that of several metres, corresponding to relief microforms like clefts and slopes where terrestrial organisms exist, particularly native vascular plants. mesoand macro-scales are scales corresponding to standard observations at meteorological stations and represent the weather conditions over the islands where our study took place.) strong responses to microclimatological conditions have already been shown for vascular plants (gerighausen et al. 2003; parnikoza et al. 2009). numerous factors often cause unpredictable changes in meteorological conditions at the micro-scale (miotke 1988). as a result, microclimatological conditions within an area as small as a few square metres can be so different that plants growing in one spot in it cannot grow in another (graae et al. 2012; convey et al. 2018). otcs, which simulate warming in manipulation experiments, are popular equipment for studying microclimatology in the antarctic. experimental studies have shown that otcs had a greater warming effect with distance from the sea, although this effect disappeared when there was strong wind and varied with land-cover type and sunshine duration (bartak et al. 2019). the temperature regime is also important (oliphant et al. 2015). warming in otcs significantly improves plant development in polar regions by making more liquid water available and increasing photosynthesis (gjessing & øvstedal 1989; bokhorst et al. 2012; saez et al. 2018; bartak et al. 2019). although otcs are excellent tools for microclimatological studies, some valuable information may be lost during otc manipulations, hindering our understanding of microto macro-scale responses in nature. overall, elevation significantly affects meteorological conditions at the micro-level, influencing plant development (cannone et al. 2016). permafrost, which occurs in the argentine islands at depths of 20–40 cm (abakumov & parnikoza 2015; parnikoza et al. 2016), is another important factor at the micro-scale. the areas with favourable conditions for plant growth are above the permafrost, and individual plants may appear on relief microforms like cracks, elevations and so on (parnikoza, berezkina et al. 2018). favourable weather conditions for plant development are complicated by animal activity (parnikoza et al. 2015; cannone et al. 2016), human activity (tin et al. 2008; convey 2011) and even the possible impact of different plant species on each other (molina-montenegro et al. 2013; casanova-katny et al. 2014; molina-montenegro et al. 2014). meteorological parameters at the micro-scale are affected by seasonal variability and reflect changes in macro-scale conditions (walton 1982; guglielmin et al. 2012; convey et al. 2018). the main drivers of the seasonal thermal regime changes at a micro-scale are the general air temperature variability, solar radiation impacts and snow cover thickness. at a micro-scale, snow cover determines the variation of soil and ground temperature as well as the intensity of cooling during the cold season (davey et al. 1992). this present study is based on data from an extensive study area covering a number of islands in the maritime antarctic. we used measurements of lt on the surface (substrate) in native vascular plants microhabitats in the argentine islands–kyiv peninsula region, on the graham coast of the antarctic peninsula (parnikoza, miryuta et al. 2018; savenets et al. 2020). we aimed to detect the most typical temperature conditions in microhabitats where vascular plants grow on particular relief microforms. this differs from previous research of microclimatological temperature changes conducted mainly in otcs (bokhorst et al. 2007; bokhorst et al. 2008; bokhorst et al. 2011; bartak et al. 2019). however, some of those otc studies also covered a relatively large area (bokhorst et al. 2007; bokhorst et al. 2008; convey et al. 2018) and included measurements taken from environments that were not artificially modified (walton 1982; davey et al. 1992; convey et al. 2018). analysis of the link between macroand microclimate is crucial for understanding the transformation of meteorological fields during the macro-to-micro-scale transition. this study aimed to define the main features of lt variability and to analyse the relationship between lt (strongly affected by microclimate) and meteorological conditions in the areas where native vascular plants grow in the argentine islands–kyiv peninsula region. this paper discusses the following questions. how deterministic is intra-annual lt variability? what is the relationship between lt (representing micro-conditions) and other meteorological parameters measured at the weather station (representing the influence of mesoand macro-conditions)? which meteorological parameters most strongly correlate with lt and are therefore helpful for monitoring terrestrial organisms, in particular vascular plants? what are the key meteorological parameters for the simple statistical approximation of daily lt in areas where terrestrial organisms exist? material and methods study area, instruments and measurement data the area of study is part of wilhelm archipelago and graham coast. for the purposes of this study, we call our study area the argentine islands–kyiv peninsula region, which encompasses part of the coast of the kyiv peninsula and some of the islands off it, including petermann island, the argentine islands, the yalour islands, the berthelot islands and darboux island (fig. 1, supplementary table s1). fig. 1 the region of study and the spatial distribution of loggers (the numbers correspond to the list of loggers in supplementary table s1). this study is based on lt data measured in an area called the bio-microclimatology experimental ground, which contains a set of points where hobo pendant temperature/light 64k data loggers collect data. the area is located mainly in the argentine islands, at a distance of 25 km around the akademik vernadsky station (the meteorological station there corresponds to logger d1, number 31 in fig. 1). the locations, short names and other information about the loggers are provided in supplementary table s1. this study is focused on the micro-scale features of the polar climate that determine local flora growth. over the course of a year, 37 mini-loggers were placed near populations of the native vascular plants deschampsia antarctica and colobanthus quitensis (kunth bartl.). it must be noted that the methodology of our lt measurements differs from the methodology of standard meteorological observations. the loggers were set on the surface (substrate) and as close to the plants as possible for the best representation of the thermal regime in which terrestrial surface organisms develop. the data measured by loggers cannot represent air, soil or plant leaf temperature, strictly speaking. nevertheless, lt values are comparable to other standard temperature data because the same radiative and heat fluxes impact lt. these data are important for both meteorological and biological studies. the installed loggers are waterproof, two-channel devices that combine temperature and light intensity measurements (fig. 2). they are suitable for measuring soil, air and water temperatures. the accuracy of the instrument is ±0.5°c for positive temperatures and ±0.7°c for negative temperatures. they can be operated at a minimum temperature of -20°c. the response time is 10 min for air temperature and 5 min for water temperature measurements. the drift of the temperature sensor in the data loggers is less than 0.1°c/yr. so light intensity could be recorded, the loggers were not shielded from sunlight. the temporal resolution of the data is 30 min; however, daily average values were calculated for the purpose of this study. fig. 2 a logger in situ at the location called cape t. the logger dies (supplementary table s1) was set near the plants that grow under the regular heating influence of diesel-powered electricity generators enclosed in a nearby hut. most of the time, this logger measured positive lt. this logger is a subject of special interest due to warmer-than-average conditions. four sources of basic meteorological information, all collected at or within 200 m of the akademik vernadsky station, were used in addition to the data from the mini-loggers: (1) daily observations of snow depth, precipitation and sunshine duration; (2) atmospheric air pressure, air and dew point temperatures, relative humidity at 2 m above ground, wind direction and wind speed at 10 m above ground measured using a vaisala aws-310 automatic weather station, with a temporal resolution of 1 min; (3) downward and reflected solar shortwave radiation fluxes, downward and upward longwave radiation fluxes, soil temperature at 1 cm depth and 2-m air temperature measured with a microclimate monitoring station (mainly developed by ems brno, and including sensors from various manufacturers), with a temporal resolution of 10 min. statistical methods all the data for a particular day were averaged. to define the prevailing wind during a particular day, the daily mean wind direction was calculated using vector computations (eqns. 1–3). first, the daily average u and v wind components were calculated based on n measurements of wind speed (v) and wind direction (d): second, the prevailing wind direction(d) was found using the following equation: where diff = + 180 for arctan(u/v) < 180 and diff = -180 for arctan(u/v) > 180. wind speed was averaged as the arithmetic mean of v without using wind components. the variance of lt is displayed using a box–whisker plot with median values, 25th and 75th percentiles and 5th and 95th percentiles for the non-outlier range. outliers are beyond the 5th and 95th percentiles. intra-annual (seasonal) variations were estimated using harmonic analysis with the lowest frequency of one year. the highest frequency was limited to two months in order to defining the main variations at a macro-scale. harmonic significance was estimated using a t-test with p = 0.05. analysis of seasonality was based on mean values (lt1) calculated as the sum of significant harmonics (seasonal model): where n is the total number of k significant harmonics, lt is the mean value, ak is the amplitude, ωk is the frequency (ωk = 2π/tk, where tk is the period of harmonic), φk is the phase and t is the time. the dependence of lt on the values of the previous day was estimated using autoregressive models. a pearson correlation was used for the analysis of the relationship between lt and meteorological parameters. statistical models based on multiple linear regression were used to estimate lt by other meteorological variables. the estimation was calculated using the following procedure. (1) linear regression with every meteorological parameter was calculated, with lt acting as a dependent variable and meteorological parameter acting as an independent variable. (2) the most significant regression equation with the highest determination coefficient (r2) was found. (3) the significance of the equation was checked using a t-test. (4) if the equation was significant, lt was calculated using a single linear regression equation. (5) the obtained values from step 4 were subtracted from the input lt time series to find the residuals. (6) a new linear regression was calculated, where the residuals of lt were acting as the dependent variable, and every meteorological parameter was acting as an independent variable. steps 2–6 were repeated until the regression was significant. as a result, an additive model was built for each time series of lt: where lti(model) is the modelled lt value for a certain day (i), xji is the meteorological parameter (predictor), αj is the regression coefficient between lt and the meteorological parameter xji, bj is the constant term (omitted if not significant) and m is the number of significant meteorological parameters (predictors). we estimated the determination coefficient (r2) separately for seasonal variations of lt, autoregressive models and daily lt models using the following equation: where mss is the sum of squares of seasonal models/autoregressive models/daily lt models (variability explained) and tss is the sum of squares of the time series (total variability). results intra-annual variability of lt at a micro-scale, lt is a variable parameter; non-outlier ranges of the loggers’ time series vary from -11 to 12˚c (fig. 3). the median temperature of all loggers varied from 0.0 to -3.0˚c (fig. 3). moreover, the medians for the majority of loggers are equidistant to the 25th and 75th percentiles, which indicates their closeness to mean values. fig. 3 box–whisker plot for lt from the loggers (for periods indicated in supplementary table s1) and for 2-m air temperature at the akademik vernadsky station, during february 2019 to march 2020. the lowest daily average lts were between -10 and -12˚c, but for most locations, it was higher than -9˚c (see outliers and non-outlier range in fig. 3). overall, lt was higher than the 2-m air temperature measured at the akademik vernadsky station. the highest daily lt varied from 8 to 13˚c, which was also usually higher than the daily 2-m air temperature at the station. there were more outliers for positive lts. it was found that lts showed clear seasonality in all geographic locations. determination coefficients (r2) of intra-annual variations varied from 0.75 to 0.93 (fig. 4, supplementary table s2). this demonstrates that at least 75% of lt behaviour could be accounted for by periodical seasonal variations. annual (first harmonic) and semi-annual (second harmonic) variations had the highest intensity and statistical significance at all locations. fig. 4 ranked r2 of lt seasonal models for the loggers (see fig. 1, supplementary table s1). our analysis shows that lt had distinct annual variations (first harmonic), which appeared as a result of temperature response to annual changes in incoming solar radiation at a given geographical location. the amplitude varied from 2.3 to 6.5˚c (supplementary table s2). semi-annual variations had the second highest impact on lt intra-annual variability. the amplitudes of semi-annual variations varied from 0.4 to 1.8˚c, but it exceeded 1.0˚c for most loggers (supplementary table s2). the harmonic analysis demonstrated the significance of higher harmonics, but additional analysis is needed for more reliable conclusions. in general, clearer seasonality was observed on rock terraces, where the average r2 of seasonal variations was higher by 2–5%. the highest amplitudes of seasonal variations were observed on rock ledges. moreover, the average first harmonic amplitude on open areas reached 5.2˚c, whereas it was ca. 4.6˚c in protected areas. the annual cycle of lt calculated for each day, using eqn. 4, is presented in fig. 5. a stable 2-m air temperature transition through 0˚c was used to distinguish cold and warm periods. the differences in lt variability during the cold season were mostly responsible for the differences in r2 of the annual cycle. changes in daily lt in january 2020 in the warm season were similar at all locations (fig. 6a) and corresponded to the thermal regime formed by macro-scale climatic conditions over the region. hence, lt variability during the warm period equally contributed to the r2 of annual variations for all loggers. fig. 5 annual cycle of lt based on the significant harmonics (1st and 2nd) for loggers with the (a) highest and (b) lowest r2 of seasonal variations. fig. 6 daily lt variability in (a) january 2020 and (b) july 2019 for loggers with the highest (logger barch.) and the lowest (logger moss sm.) r2 of seasonal variations. in contrast to the warm season, lts varied significantly during the cold months and depended on the location (fig. 6b). these differences impacted the significance (i.e., r2) of annual lt variability. some locations had lt changes that were nearly consistent over the whole cold season with values of approximately -4˚c (e.g., logger barch., fig. 6b). these areas were most likely located under a thick layer of snow cover and could therefore not reflect air temperature changes over the region. as a result of such a steady lt value, annual variations for these loggers had higher r2. at other locations, lts continued to replicate the air temperature regime with clearly visible day-to-day variability (e.g., logger moss sm., fig. 6b). higher day-to-day variability during the cold season resulted in lower r2 of the annual cycle. after the seasonal variations were estimated, we calculated residuals, so any significant intra-annual variability was extracted from the time series. the residuals’ computations (seasonality removal) procedure was applied to each logger and each daily value (ltt) separately: where ltres_t is the lt residual for each day t and ltt is the average value, computed using eqn. 4. the autoregression of lt was analysed using residuals (ltres_t). it enabled us to determine the dependency on lt during the previous day (ltres_t-1), demonstrating how inertial lt was at a given location. r2 of the autoregressive part varied from 0.20 to 0.58 (fig. 7, supplementary table s2). fig. 7 ranked autoregressive r2 of lt residuals in the argentine islands region. loggers with higher r2 indicated locations where air temperature changes were slower, i.e., lt inertia was higher. in contrast, loggers with low autoregressive r2 values indicated more open areas where lts were stronger, depending on external weather conditions. typically, lts on rock terraces and open areas showed lower r2 in autoregressive models, whereas the highest values were found on rock ledges, in clefts and in protected areas. the sum of intra-annual variations and autoregressive parts gives a total r2 of 0.88–0.97. 3 to 12% of lt variability could not be described using the sum of periodic intra-annual changes and autoregression. the attempt to find dependencies between final residuals of lt and meteorological parameters did not show significant results. for some loggers, correlation was identified with moss surface temperature (r = 0.06…0.57) and air temperature (r = 0.11…0.60). the relationship between lt residuals and moss surface temperature could indicate that plants have a micro-scale influence on the thermal regime, in particular, areas where they grow, as shown by hrbáček et al. (2020) and perera-castro et al. (2020). the dependence between lt residuals and air temperature is obvious: there are other processes with higher frequencies (e.g., the southern annular mode, synoptic processes) that influence the air temperawture and were not clearly indicated in lt variability. overall, our analysis has shown that the intra-annual variability of lt is rather deterministic, with less than 12% of unexplained variability. it indicates that the thermal regime in the areas where terrestrial organisms exist is not greatly isolated microclimatologically and closely reflects changes in the thermal regime at a macro-scale. using meteorological parameters to approximate lt to demonstrate the strength of the relationship between lt and the macro-scale meteorological measurements representative for the region under study, we estimated the relationship between individual daily lt observations and meteorological variables from the akademik vernadsky weather station, the vaisala aws-310 automatic weather station and the microclimate monitoring station. as meteorological variables are interconnected, we analysed the relationships step by step from the highest correlation to the lowest one (which was still significant) using the procedure explained earlier. as expected, correlations between lt and other temperature parameters were the strongest. the best correlations, ranging r = 0.63 to r = 0.81, were found between lt and 2-m air temperature (fig. 8). better relationships were found for loggers located on the rock slopes (e.g., darb., fig. 8), where lt fell below -5˚c during the period with negative air temperatures. this implies that these loggers were less insulated. the worst relationships between lt and 2-m air temperature were found on rock terraces (e.g., port char., fig. 8) because the lt was quite stable during the cold period, with values of 0 to -4˚c, while 2-m air temperature frequently dropped below -10˚c. overall, 2-m air temperature can be considered as the main predictor for lt at all locations, with regression coefficients varying from 0.336 to 1.035 (supplementary table s3). fig. 8 relationship between lt and 2-m air temperature, shown by the examples of (a) the logger darb. (r = 0.81) and (b) the logger port char. (r = 0.63). after the air temperature impact on lt was estimated, the regression dependences were subtracted from the time series. this procedure allowed us to avoid false significance with other parameters that correlate with air temperature. the second step of calculations showed significance of wind speed. correlations between lt residuals (with subtracted air temperature impact) and wind speed varied from r = 0.32 to r = 0.46 (supplementary table s3). the impact of wind speed was most pronounced on rock ledges. regression coefficients were negative and ranged -0.329 to -0.616 (supplementary table s3); thus, as expected, greater wind speed increase caused 2-m and lt cooling. at all locations, both 2-m air temperature and wind speed had the best relationships with lt. no other meteorological parameters were significant for all locations. they can therefore be used as key meteorological parameters for simple lt statistical modelling to estimate their joint impact. these models are the simplest way to combine lt at the micro-scale with meteorological parameters representing atmospheric conditions at a larger scale. as the regression models were calculated for every logger, their multi-model ensemble will help us to understand the lt conditions that allow plants to establish themselves in this harsh environment. the generalized equation for the daily average lt is: where tair is the daily averaged 2-m air temperature in ˚c, v is the daily averaged wind speed in m/s and a and b are regression coefficients (supplementary table s3). temporal distributions of observed lt with modelled values are presented in fig. 9 for the cases of loggers with the highest and the lowest r2. overall, r2 for the first model varies from 0.46 to 0.68 (fig. 10). some of the loggers, like darb. (figs. 9, 10), show a good fit between observed and modelled values even during the cold period. with negative air temperatures, these loggers have clear variations that could be modelled. other loggers, like port char. (figs. 9, 10), are characterized by an absence of variations during the cold period. during the cold period, low variance of observed lt (e.g., logger port char., fig. 9) implied a thicker insulated layer over the logger, i.e., steady snow cover. fig. 9 temporal distribution of observed and modelled lt, shown by the examples of (a) the logger darb. (r2 = 0.68) and (b) the logger port char. (r2 = 0.46). fig. 10 dependencies between observed and modelled lt values for (a) the logger darb., which had the highest r2, and (b) the logger port char., which had the lowest r2. x and y axes are unified. on the basis of the lt regression models, it is possible to indicate which loggers (and consequently which terrestrial organisms, in particular plants) were more open and less influenced by relief microforms. all the model values are cooler than the observed lt (fig. 9). this indicates the role of other factors, some of which might relate to relief microforms and surface closeness. lower model r2 was more typical for rock terraces because of the lower regression coefficients of air temperature. in contrast, the best model results were for lt measurements on rock slopes, on the account of the better regression with air temperature, and at rock ledges because of closer relationships with wind speed. dependency of model resulting from distance to the weather station and elevation was not found. no differences in model results were found between north and north-west expositions of the relief microforms on which all loggers were situated. the statistical models based on regression dependencies from air temperature and wind speed with a set of calculated coefficients (supplementary table s3) could be used to build an ensemble to predict lt on various sites. in spite of the absence of direct measurements, temperature in the limited spots that allow plants to establish themselves could be approximated using these 37 regression equations. it should be noted that the relationships between lt and air temperature at the station are formed under a variety of synoptic processes during the year. we analysed the impact of prevailing wind on temperature parameters for warm and cold periods separately. the relationship between lt and prevailing wind was similar for all loggers, but the daily average lt differed. west and south winds transported air masses from the ocean, and lts reached higher values. prevailing east winds brought air from the antarctic peninsula, and lts were lower. this effect was especially strong during the cold period (fig. 11b). fig. 11 typical plots of daily average lts, showing the example of the logger berth., during the days with different prevailing wind directions in (a) the warm period and (n) the cold period. during the warm period, lt was less dependent on prevailing wind directions. winds from the west brought the warmest air masses, although lt did not differ much between east and north winds. statistically reliable data were absent for the north-west winds during the warm period (fig. 11a) because only a few synoptic cases were observed. no other meteorological parameters remained statistically significant for all locations once the impact of 2-m air temperature and wind speed was subtracted from the time series (supplementary table s4). only sunshine duration and the upward longwave radiation flux remained statistically significant for loggers at some sites (supplementary table s4). the analysis did not reveal any clear relationships with daily precipitation sums, snow depth, downward longwave and downward and upward shortwave radiation fluxes. although these parameters are crucial for the lt regime where plants grow, their measurements at a single site cannot be representative of other locations because of the heterogeneous nature of micro-relief forms and microclimates even within a fairly small area. after we considered air temperature and wind speed impact (using eqn. 8) and calculated lt residuals, all other interconnected parameters lost their significance: soil and dew-point temperatures, relative humidity and air pressure (supplementary table s4). correlations between lt and sunshine duration varied from 0.04 to 0.48 (supplementary table s4). coefficients were higher for north-facing rock ledges, whereas data from rock terraces did not show strong correlations. the higher correlations for many locations can be explained by certain land-cover types absorbing radiation. lts were correlated with upward longwave radiation flux at only 13 locations (supplementary table s4), with coefficients varying from -0.23 to 0.40. we did not find any similarity among locations where correlations between lts and radiation fluxes were significant. overall, the availability of radiation measurements only near the akademik vernadsky station greatly limited the accuracy of the analysis. discussion and conclusions we used experimental lt measurements that cannot strictly be considered as air, soil or plant leaf temperatures since the loggers were located on the substrate surface where native vascular plants grow. nevertheless, our results have shown that lts had typical seasonality and other variabilities of the temperature regime in the region and can represent the microclimatic conditions faced by native vascular plants at selected locations. similar patterns were shown by walton (1982), guglielmin et al. (2012) and convey et al. (2018), who demonstrated that air temperature influences the seasonal variability of ground temperature. temperature seasonality has also been detected in the active ground layer (guglielmin et al. 2012). in our study, lts measured on the substrate surface showed clear seasonal variations, accounting for 75 to 93% of total lt variability, which is mainly caused by the significant annual and semi-annual variations. better seasonality was observed on open rock terraces and lower on rock slopes and ledges. we have shown that differences in r2 of the lt annual cycle are formed mainly by the differences in day-to-day lt changes during the cold season (defined as a period with negative celsius temperatures). although our study was based on a short time series, the results are consistent with temperature variability in the antarctic (see davey et al. 1992; van der broeke 2000; smith & stammerjohn 2001; turner et al. 2021). overall, 3 to 12% of lt variability could not be described using the sum of periodic intra-annual changes and the autoregressive dependency. on a daily scale, the highest correlation between lt (which represents microclimate conditions) and meteorological parameters (which represent the influence of mesoand macro-scale climatic conditions) was found with air temperature, with higher values at rock slopes compared to rock terraces and ledges. wind speed was the second parameter that had significant correlations with lts at all locations, with a better relationship on rock ledges. both 2-m air temperature and wind speed could be used as the simplest way to estimate lt at a micro-scale in the vascular plants’ microhabitat, where no other regular and more complex measurements are possible. better modelling results were obtained for locations where lts had clear variability during the cold season under negative air temperatures. worse results were for loggers with almost stable lt during the cold season. we were not able to measure snow depth at these remote locations with the loggers. however, our results showed the well-known effect of snow cover and its depth on the temperature regime close to the ground and on plants’ microhabitats (davey et al. 1992; bokhorst et al. 2016; tarca et al. 2022). the almost constant lts during the cold season corresponded to the locations with thicker insulating snow cover. overall, lt could be estimated better at rock ledges (where stronger correlations with wind speed were obtained) and at rock slopes (where stronger correlations with air temperature were obtained). however, all the models simulated lt colder than observed. our study has confirmed that microclimatological differences of lts appeared under the influence of incoming solar irradiance, which is extremely important for biota (walton 1982; bokhorst et al. 2012; convey et al. 2018; hrbáček et al. 2020). however, using radiation parameters for lt approximation presented a number of difficulties: the only available data were from distant meteorological stations; there was a possible warming effect for loggers exposed to direct solar radiation; cloudiness had a heterogeneous influence. this present study helps us to understand lt variations at a micro-scale and how they correspond to macro-scale changes. temperature conditions near the surface, where terrestrial organisms exist, have typical seasonal behaviour, but a few differences were revealed. most remote locations made it impossible to provide regular meteorological measurements. nonetheless, we have proposed a simple statistical approach based on the regression dependencies with 2-m air temperature and wind speed to estimate lt changes in the argentine islands–kyiv peninsula region. because of the location of temperature loggers in native vascular plant microhabitat, it might also become possible to validate numerical weather models using temperature data from the most favourable areas for biological applications. acknowledgements the authors acknowledge kamil laska and his work for allowing us to use data from the microclimate monitoring station, which has been supported by the masaryk university project under muni/a/0952/2013 analysis, evaluation, and visualization of global environmental changes in the landscape sphere. the authors are grateful to anna evchun, at the state institution national antarctic scientific center, kyiv, ukraine, for preparing the map of the region and spatial distribution of loggers. the authors thank the reviewers whose valuable comments and constructive criticism allowed us to improve the paper. the authors thank david crookall for help in manuscript proofreading. last but not least, the authors acknowledge the armed forces of ukraine, local territory defense forces and volunteers for making it possible for us to complete this work. references abakumov e.v. & parnikoza i.y. 2015. determination of the soil–permafrost border in two maritime antarctic regions on the base of vertical electric sounding data. ukrainian antarctic journal 14, 138–142, doi: 10.33275/1727-7485.14.2015.182. aerts r., cornelissen j.h.c. & dorrepaal e. 2006. plant performance in a warmer world: general responses of plants from cold, northern biomes and the importance of winter and spring events. plant ecology 182, 65–77, doi: 10.1007/s11258-005-9031-1. bartak m., laska k., hajek j. & vaczi p. 2019. microclimate variability of antarctic terrestrial ecosystems manipulated by open top chambers: comparison of selected austral summer seasons within a decade. czech polar reports 9, 88–106, doi: 10.5817/cpr2019-1-8. bokhorst s., huiskes a., aerts r., convey p., cooper e.j., dalen l., erschbamer b., gudmundsson j., hofgaard a., hollister r.d., johnstone j., jónsdóttir i.s., lebouvier m., van de vijver b., wahren c.-h. & dorrepaal e. 2012. variable temperature effects of open top chambers at polar and alpine sites explained by irradiance and snow depth. global change biology 19, 64–74, doi: 10.1111/gcb.12028. bokhorst s., huiskes a., convey p. & aerts r. 2007. the effect of environmental change on vascular plant and cryptogam communities from the falkland islands and the maritime antarctic. bmc ecology 7, article no. 15, doi: 10.1186/1472-6785-7-15. bokhorst s., huiskes a., convey p., sinclair b.j., lebouvier m., van de vijver b. & wall d.h. 2011. microclimate impacts of passive warming methods in antarctica: implications for climate change studies. polar biology 34, 1421–1435, doi: 10.1007/s00300-011-0997-y. bokhorst s., huiskes a., convey p., van bodegom m. & aerts r. 2008. climate change effects on soil arthropod communities from the falkland islands and the maritime antarctic. soil biology and biochemistry 40, 1547–1556, doi: 10.1016/j.soilbio.2008.01.017. bokhorst s., pedersen s.h., brucker l., anisimov o., bjerke j.w., brown r.d., ehrich d., essery r., heilig a., ingvander s., johansson c., johansson m., jónsdóttir i.s., inga n., luojus k., macelloni g., mariash h., mclennan d., rosqvist g.n., sato a., savela h., schneebeli m., sokolov a., sokratov s.a., terzago s., vikhamar-schuler d., williamson s., qiu y. & callaghan t.v. 2016. changing arctic snow cover: a review of recent developments and assessment of future needs for observations, modelling, and impacts. ambio 45, 516–537, doi: 10.1007/s13280-016-0770-0. cannone n., guglielmin m., convey p., worland m.r. & favero longo s.e. 2016. vascular plant changes in extreme environments: effects of multiple drivers. climatic change 134, 651–665, doi: 10.1007/s10584-015-1551-7. cannone n., guglielmin m., malfasi f., hubberten h.w. & wagner d. 2021. rapid soil and vegetation changes at regional scale in continental antarctica. geoderma 394, 115017, doi: 10.1016/j.geoderma.2021.115017. casanova-katny m.a., palfner g., torres-mellado g. & cavieres l.a. 2014. do antarctic lichens modify microclimate and facilitate vascular plants in the maritime antarctica? a comment to molina-montenegro et al. (2014). journal of vegetation science 25, 601–605, doi: 10.1111/jvs.12122. convey p. 2011. antarctic terrestrial biodiversity in a changing world. polar biology 34, 1629–1641, doi: 10.1007/s00300-011-1068-0. convey p. 2012. polar terrestrial environments. in e. bell (ed.): life at extremes: environments, organisms and strategies for survival. pp. 81–102. wallingford: cab international. convey p., coulson s.j., worland m.r. & sjöblom a. 2018. the importance of understanding annual and shorter-term temperature patterns and variation in the surface levels of polar soils for terrestrial biota. polar biology 41, 1587–1605, doi: 10.1007/s00300-018-2299-0. convey p. & smith r. 2006. responses of terrestrial antarctic ecosystems to climate change. plant ecology 182, 1–10, doi: 10.1007/s11258-005-9022-2. davey m., pickup j. & block w. 1992. temperature variation and its biological significance in fellfield habitats on a maritime antarctic island. antarctic science 4, 383–388, doi: 10.1017/s0954102092000567. gerighausen u., brautigam k., mustafa o. & peter h.u. 2003. expansion of vascular plants on an antarctic island as a consequence of climate change? in a. huiskes et al. (eds.): antarctic biology in a global context. pp. 79–83. leiden: backhuys publishers. gjessing y. & øvstedal d.o. 1989. microclimates and water budget of algae, lichens and a moss on some nunataks in queen maud land. international journal of biometeorology 33, 272–281, doi: 10.1007/bf01051089. graae b.j., de frenne p., kolb a., brunet j., chabrerie o., verheyen k., pepin n., heinken t., zobel m., shevtsova a., nijs i. & milbau a. 2012. on the use of weather data in ecological studies along altitudinal and latitudinal gradients. oikos 121, 3–19, doi: 10.1111/j.1600-0706.2011.19694.x. guglielmin m., worland m.r. & cannone n. 2012. spatial and temporal variability of ground surface temperature and active layer thickness at the margin of maritime antarctica, signy island. geomorphology 155–156, 20–33, doi: 10.1016/j.geomorph.2011.12.016. hogg i.d., cary s.c., convey p., newsham k.k., o’donnell a.g., adams b.j., aislabie j., frati f., stevens m.i. & wallh d.h. 2006. biotic interactions in antarctic terrestrial ecosystems: are they a factor? soil biology & biochemistry 38, 3035–3040, doi: 10.1016/j.soilbio.2006.04.026. hrbáček f., cannone n., kňažková m., malfasi f., convey p. & guglielmin m. 2020. effect of climate and moss vegetation on ground surface temperature and the active layer among different biogeographical regions in antarctica. catena 190, article no. 104562, doi: 10.1016/j.catena.2020.104562. miotke f.-d. 1988. microclimate, weathering processes and salt within ice-free continental antarctica. polarforschung 58, 201–209. molina-montenegro m.a., ricote-martínez n., muñoz-ramírez c., gómez-gonzález s., torres-díaz c., salgado-luarte c. & gianoli e. 2013. positive interactions between the lichen usnea antarctica (parmeliacea) and the native flora in maritime antarctica. journal of vegetation science 24, 463–472, doi: 10.1111/j.1654-1103.2012.01480.x. molina-montenegro m.a., torres-diaz c. & gianoli e. 2014. antarctic macrolichen modifies microclimate and facilitates vascular plants in the maritime antarctica—a reply to casanova-katny et al. (2014). journal of vegetation science 25, 606–608, doi: 10.1111/jvs.12141. oliphant a.j., hindmarsh r., cullen n. & lawson w. 2015. microclimate and mass fluxes of debris-laden ice surfaces in taylor valley, antarctica. antarctic science 27, 85–100, doi: 10.1017/s0954102014000534. parnikoza i.y., abakumov e.v., dykyy i.v., pilipenko d.v., shvydun p.p., kozeretska i.a. & kunakh v.a. 2015. vlijanie ptic na prostranstvennoe raspredelenie deschampsia antarctica desv. ostrova galindez (argentinskie ostrova, priberežnaja antarktika). (influence of birds on the spatial distribution of desсhampsia antarctica [desv.] on galindez island [argentinean islands, coastal antarctic].) vestnik of saint petersburg university, series 3, biology 1, 78–97. (in russian with english abstract.) parnikoza i.y., abakumov e.v., korsun s., klymenko i., netsyk m., kudinova a. & kozeretska i. 2016. soils of the argentine islands, antarctica: diversity and characteristics. polarforschung 86, 83–96, doi: 10.2312/polarforschung.86.2.83. parnikoza i.y., berezkina a., moiseyenko y., malanchuk v. & kunakh v. 2018. kompleksna harakterystyka rajonu argentynskih ostroviv ta ostrova galindez (morska antarktyka) jak poligonu dlja vyvčennja dynamiki nazemnoji roslynnosti. (complex survey of the argentine islands and galindez island [maritime antarctic] as a research area for studying the dynamics of terrestrial vegetation.) ukrainian antarctic journal 17, 73–101, doi: 10.33275/1727-7485.1(17).2018.34. (in ukrainian with english abstract on the website.) parnikoza i.y., convey p., dykyy i., trokhymets v., milinevsky g., inozemtseva d. & kozeretska i. 2009. current status of the antarctic herb tundra formation in the central argentine islands. global change biology 15, 1685–1693, doi: 10.1111/j.1365-2486.2009.01906.x. parnikoza i.y., miryuta n.y., ivanets v.y. & dykyi e.o. 2018. vyznačennja zvedenogo latentnogo pokaznyka prystosovanosti (zlpp) iz vrahyvannjam vnesku dejakyh pokaznykiv dovkillja dlja popyliacij deschampsia antarctica ostrova galindez (morska antarktika) v sezon 2017/2018. (determination of the united quality latent index of adaptability [uqlia] and contribution of some environmental parameters to it for deschampsia antarctica populations, galindez island [maritime antarctic] season 2017/2018.) the bulletin of vavilov society of geneticists and breeders of ukraine 16, 190–202, doi: 10.7124/visnyk.utgis.16.2.1057. (in ukrainian with english abstract on the website.) perera-castro a.v., waterman m.j., turnbull j.d., ashcroft m.b., mckinley e., watling j.r., bramley-alves j., casanova-katny a., zuniga g., flexas j. & robinson s.a. 2020. it is hot in the sun: antarctic mosses have high temperature optima for photosynthesis despite cold climate. frontiers in plant science 11, article no. 1178, doi: 10.3389/fpls.2020.01178. saez p., cavieres l.a., galmés j., gil‐pelegrín e., peguero‐pina j.j., sancho‐knapik d., vivas m., sanhueza c., ramírez c.f., rivera b.k., corcuera l.j. & bravo l.a. 2018. in situ warming in the antarctic: effects on growth and photosynthesis in antarctic vascular plants. new phytologist 218, 1406–1418, doi: 10.1111/nph.15124. savenets m., pysarenko l. & pishniak d. 2020. microclimatic variations of land surface temperature on galindez island (western part of the antarctic peninsula). ukrainian antarctic journal 2, 3–15, doi: 10.33275/1727-7485.2.2020.648. smith r. & stammerjohn s. 2001. variations of surface air temperature and sea-ice extent in the western antarctic peninsula region. annals of glaciology 33, 493–500, doi: 10.3189/172756401781818662. tarca g., guglielmin g., convey p., worland m.r. & cannone n. 2022. small-scale spatial–temporal variability in snow cover and relationships with vegetation and climate in maritime antarctica. catena 208, article no. 105739, doi: 10.1016/j.catena.2021.105739. tin t., fleming z.l., hughes k.a., ainley d.g., convey p., moreno c.a., pfeiffer s., scott j. & snape i. 2008. impacts of local human activities on the antarctic environment. antarctic science 21, 3–33, doi: 10.1017/s0954102009001722. turner j., barrand n.e., bracegirdle t.j., convey p., hodgson d.a., jarvis m., jenkins a., marshall g., meredith m.p., roscoe h., shanklin j., french j., goosse h., guglielmin m., gutt j., jacobs s., kennicutt m.c., masson-delmotte v., mayewski p., navarro f., robinson s., scambos t., sparrow m., summerhayes c., speer k. & klepikov a. 2013. antarctic climate change and the environment: an update. polar record 50, 237–259, doi: 10.1017/s0032247413000296. turner j., colwell s.r., marshall g.j., lachlan-cope t.a., carleton a.m., jones p.d., lagun v., reid p.a. & iagovkina s. 2005. antarctic climate change during the last 50 years. international journal of climatology 25, 279–294, doi: 10.1002/joc.1130. turner j., lu h., king j., marshall g.j., phillips t., bannister d. & colwell s. 2021. extreme temperatures in the antarctic. journal of climate 34, 2653–2668, doi: 10.1175/jcli-d-20-0538.1. van der broeke m.r. 2000. the semiannual oscillation and antarctic climate, part 5: impact on the annual temperature cycle as derived from ncep/ncar re-analysis. climate dynamics 16, 369–377, doi: 10.1007/s003820050334. walther g.-r., post e., convey p., menzel a., parmesan c., beebee t., fromentin j.-m., hoegh-guldberg o. & bairlein f. 2002. ecological responses to recent climate change. nature 416, 389–395, doi: 10.1038/416389a. walton d.w.h. 1982. the signy island terrestrial reference sites: xv. micro-climate monitoring, 1972–1974. british antarctic survey bulletin 55, 111–126. wmo 2010. guide to the global observing system. 2010 edition. updated in 2017. wmo-no. 488. geneva: world meteorological organization. thorarinsdottir.indd 217thorarinsdóttir & gunnarsson 2003: polar research 22(2), 217–223 reproductive cycles of mytilus edulis l. on the west and east coasts of iceland gudrun g. thorarinsdóttir & karl gunnarsson studies evaluating the reproductive pattern of mytilus edulis l. were conducted in western and eastern iceland at two sites at about the same latitude but with different temperature regimes. mussels were sampled once or sometimes twice a month during two years in breidifjördur, western iceland and one year at mjoifjördur, eastern iceland. gonad development was monitored by microscopic observation of thin sections of the gonads. the initiation of gonad development was observed in january in breidifjördur while in mjoifjördur some of the animals started developing gonads in october, a month before spawning was over in the population. spawning started in late june or july, peaked in august and continued until november at both sites. nutrient reserve stores seemed to be limited and used for initiation of gonad development in winter but were not suffi cient for maturation of the gonads. the main growth of the gonads occured in spring in conjunction with phytoplankton blooming and renewal of food resources. g. g. thorarinsdóttir & k. gunnarsson, marine research institute, skúlagata 4, is-101 reykjavík, iceland. gutho@hafro.is. considerable effort has been devoted to research on different aspects of the reproduction of the marine mussel mytilus edulis l. in different parts of the world (seed & suchanek 1992). because of the commercial importance of m. edulis in the north atlantic, comprehensive studies have been undertaken and the literature relating to reproduction is particularly extensive for the area (seed 1969, 1976; seed & brown 1977; brousseau 1983; sprung 1983; barkati 1990; snodden & roberts 1997). however, in iceland investigations of the reproduction of this species are sparse (thorarinsdóttir 1996). m. edulis is a sedentary organism and subjected to a wide range of environmental conditions. the interaction between reproductive processes and environmental changes may assume great importance for the well-being of the population. great variations have been observed in the reproduction pattern of m. edulis. these variations have been linked to different environmental factors such as temperature and food availability, thought to effect reproduction of mussels (giese 1959; seed 1976; kautsky 1982; newell et al. 1982; starr et al. 1990). however, no conclusive evidence of a direct effect of environmental factors on the initiation of different phases in the development and maturation of gonads has been presented except in the case of the onset of spawning in already ripe individuals (see e.g. starr et al. 1990). in the north atlantic m. edulis is subjected to environmental conditions characterized by extremely low water temperatures for several months of the year. in an attempt to more clearly defi ne the gametogenic cycle and spawning of m. edulis in iceland and to make comparisons with other populations in the north atlantic the results of a two year study in breidifjördur, western iceland, and a one year study in mjoifjördur, eastern iceland (fig. 1), are presented in this paper. furthermore, the gametogenic cycle and spawning time are 218 reproductive cycles of mytilus edulis l., iceland considered in relation to temperature and food availability as refl ected in concentrations of chlorophyll-a (chl-a). material and methods throughout the study period the sea temperature was monitored at 2 m depth every two hours with a continuous temperature recorder (starmon®, star-oddi, reykjavík) close to both sampling sites (fig. 1). at the same sites 1 liter seawater samples were taken at 2 m depth twice a month in the beginning and the end of the year and once a week from the middle of march to the end of september for analysis of chl-a and 300 ml to measure salinity. the chlorophyll samples were fi ltered through gf/c fi lters, which were frozen for later analysis. in the laboratory the chlorophyll was extracted from the fi lters with 90 % acetone and the extract measured with a spectrophotometer (jeffrey & humphrey 1975). the salinity was measured with a conductivity meter against standard salinity solution (dhi, copenhagen). about 30 mussels, 3 5 cm in shell length, were collected in the littoral zone at low tide from the study site in breidifjördur and from a suspended population in mjoifjördur at 2 m depth. the population in breidifjördur was continuously submerged except at lowest tide about 6 hours per month. the greatest difference between ebb and low tide in breidifjördur is about 6 m, but in mjoifjördur it is only about 1 m. the population structure density and size distribution were similar at both sites. the samples were collected twice a month between march and november but monthly at other times of the year. the investigations were carried out from july 1995 to august 1997 in breidifjördur and from january to november 2000 in mjoifjördur. in the laboratory small samples of the gonads were removed from the mussels and preserved in 10 % formaldehyde. later histological preparations were made by dehydration of the gonad samples through an ascending alcohol series, clearing in toluene and embedding in paraffi n. sections were cut about 7 µm in thickness and stained with hematoxylin and eosin. the stained gonad preparations from each mussel were classifi ed into different developmental stages, under a microscope, using 80 × magnifi cation. the classifi cation consisted of four main stages, two of which (developing and spawning) were further divided into four substages, resulting in a total of ten stages, developing (1 4), ripe (5), spawning (4 1) and spent (0) (seed 1969). in stage 0 (spent) it is diffi cult to determine the sex of the animals but in some cases eggs were visible even though the spawning was over. in these cases the samples were classifi ed as spent and the sex was given. the reproductive condition of the population was assessed by calculating a mean gonad index. this was done by multiplying the number of mussels in each stage by the numerical ranking of that stage and dividing the resulting value by the total number of mussels in the sample. the mean gonad index for each sampling date was then calculated by adding together the scores for all stages (seed 1969). if all individuals were spent, the gonad index would be 0 (minimum) and if all individuals were fully ripe the index would be 5 (maximum). results temperature the maximum mean monthly sea temperature in breidifjördur, western iceland, was reached in july and august in 1995 (10.1 °c) and in august 1996 (11.0 °c). the minimum temperature was observed in february 1996 (0.8 °c) and in march 1997 (–0.1 °c; fig. 2). the maximum mean monthly sea temperature in mjoifjördur, eastern iceland, was observed in august (9.8 °c) and the minimum (1.3 °c) in march. fig. 1. the study sites for mytilus edulis in western and eastern iceland. 219thorarinsdóttir & gunnarsson 2003: polar research 22(2), 217–223 salinity in breidifjördur small variations in salinity were observed. salinity ranged from a minimum of 33.8 in september 1995 and march 1996 to a maximum of 34.9 in october 1996. in mjoi fjördur salinity varied much more than in breidifjördur. the salinity varied between 32 and 34 from february until may, then fell abruptly to a minimum of 13.6 in the middle of may, increased rapidly again to a steady level of 32 33 until july, when it decreased to 22 28. the salinity increased to about 33 again in august and kept that level to the end of the year. chlorophyll-a a maximum of the mean monthly values of chl-a in breidifjördur was reached in july and september 1995 (2.1µg l-1) and in july 1996 (1.8 µg l-1). a minimum of 0.2 µg l-1 was observed in december 1995 and in november 1996. the maximum values observed in 1995 were in july 15 (3.2 µg l-1) and september 16 (4.5 µg l-1). in 1996 the maximum value was observed on 17 july (2.2 µg l-1). a minimum value was 0.2 µg l-1 on 23 december 1995 and 23 november 1996 (fig. 3). in mjoifjördur the chl-a level was below detection limit in the samples from january through april. it started increasing in late may and the mean monthly values peaked in july at 2.7 µg l-1. a maximum value of 3.7 µg l-1 was observed in the end of july (fig. 3). gametogenic cycle in breidifjördur, western iceland, there appeared to be no difference in gametogenesis or spawning between males and females and the general patterns of gametogenesis and spawning were similar in both years investigated. the highest values of the mean gonad index, 4.2 and 4.8, were fig. 2. sea surface temperature at the sampling site in breidifjördur, western iceland, from july 1995 to may 1997 and in mjoifjördur, eastern iceland, from january to december 2000. fig. 3. chlorophyll-a concentration at the sampling site in breidifjördur, western iceland, from july 1995 to march 1997 and in mjoifjördur, eastern iceland, from january to october 2000. 220 reproductive cycles of mytilus edulis l., iceland attained in july both years investigated (fig. 4) coinciding with highest number of ripe individuals (fig. 5). at the start of the sampling period in july 1995, 38 % of the population > 30 mm was spawning. the main spawning period was in august (100 %) but some spawning continued until november. in 1996 few individuals spawned in july (13 %) but the main spawning period was again in august (82 %), continuing through the autumn. in 1997 spawning started a month earlier than the year before or in june (10 %) but was most intensive in july and august (56 % each month). after the marked spawning period, both years investigated, the gonad index fell to a minimum (0.2) in november (fig. 4) when most of the individuals were in the spent condition (fig. 5). in january the gonad index slowly increased again (fig. 4) with most of the individuals investigated in developing stages until may (fig. 5). in mjoifjördur, eastern iceland, the highest gonad index, 4.2, was attained in june (fig. 4) coinciding with highest percentage of the population (50 %) in the ripe condition (fig. 6). spawning started in july and by the end of july, 87 % of the individuals in the sample were spawning. in august over 90 % of the individuals investigated were spawning. during the spawning period the gonad index decreased and in the middle of september its lowest value, 0.6, was observed (fig. 4). at this time about 60 % of the individuals were spawning but 40 % were in the spent condition (fig. 6). the development of gonads started immediately after spawning in the autumn and fully mature gametes were observed but now in small and few follicles. in october and november about 30 % of the population was still spawning and all stages of gametogenesis were observed except ripe individuals (fig. 6). discussion the gametogenic cycle in the m. edulis population in breidifjördur, western iceland, was similar both years investigated. development of gonads started in january, spawning started in july, it peaked in the beginning of august and extended until november. in mjoifjördur, eastern iceland, gametogenic cycle was different from the one in breidifjördur as gametogenesis reinitiated in about half of the population in october and november while about one third of the population was still spawning. the follicles containing the gametes were, however, smaller and fewer than in the summer, indicating that gamete production and spawning was coming to an end. the development of the gametes in mjoifjördur was slower in spring and the spawning started later in the summer than in breidifjördur. only a single period of spawning was observed at both sites. a similar gametogenic cycle with peak spawning in late summer has been observed in a suspended population in south-western iceland (thorarinsdóttir 1996). the pattern of temperature changes differs in the two areas. with lower winter temperatures and higher summer temperatures, the amplitude is greater in breidifjördur than in mjoifjördur. this difference might cause faster development of the gonads in the spring in breidifjördur than in mjoifjördur although earlier phytoplankton blooming is also a possible causal factor. the development of gonads has been related to changes in temperature (lubet 1959; bayne 1975; fig. 4. mean monthly gonad index of m. edulis from a population in breidifjördur, western iceland, from july 1995 to august 1997 and in mjoifjördur, eastern iceland, from january to november 2000. 221thorarinsdóttir & gunnarsson 2003: polar research 22(2), 217–223 gray et al. 1997) and temperature changes have also been shown to initiate spawning in already mature m. edulis (chipperfi eld 1953; sprung 1983). in fact some authors have suggested that critical temperature changes are needed for initiation of spawning in m. edulis (seed 1976; kautsky 1982), while others have found little or no evidence of this (newell et al. 1982; seed & suchanek 1992). the salinity in breidifjördur was relatively stable all the time investigated but in mjoifjördur the salinity fl uctuations are greater. the salinity decreased abruptly and intensively in may, for example. but this could not be connected to any events in the development of the gonads or spawning. fell & balsamo (1985) equally failed to establish any such association in m. edulis, although salinity changes have been connected with the onset of spawning in the related mussel perna viridis (parulekar et al. 1982). at both breidifjördur and mjoifjördur the development of the gonads in m. edulis took place during the middle of the winter when food supply, gauged by chl-a values and sea temperature, were near their respective minima. gametogenesis is therefore likely to have depended on accumulated reserves from the previous year. the increasing food supply and water temperature in april in breidifjördur and a month later in mjoifjördur seem to have accelerated the gonad development, leading to maturation in june in breidifjördur and in the middle of july in mjoifjördur at sea temperatures of about 8 °c. the annual reproductive cycle of m. edulis has fig. 6. percentage of m. edulis from mjoifjördur, eastern iceland, in each phase of the gametogenic cycle from january to november 2000. fig. 5. percentage of m. edulis from breidifjördur, western iceland, in each phase of the gametogenic cycle from july 1995 to may 1997. 222 reproductive cycles of mytilus edulis l., iceland been related to the seasonal cycle in food supply (thompson 1979; newell et al. 1982). spawning is thought to be timed such that both larvae and adults have access to abundant food supplies (thompson 1979; newell et al. 1982). since food availability is likely to infl uence larval success in marine benthic invertebrates, the use of phytoplankton as a cue for spawning could be an adaptation to ensure abundance of food for the planktotrophic larvae that attain the feeding veliger stage within a few days after spawning. the food supply for the mussels at both sites was highest at the onset of spawning in july and was relatively high until october. the larvae have thus probably had abundant food supply during development and settlement. there is a considerable variation in the timing and duration of gametogenesis and spawning in m. edulis (lowe et al. 1982). in many european populations nutrient reserve, which have accumulated in the mantle tissue during the summer, functions as an energy source for gametogenesis during autumn and winter when food supply is limited (gabbott 1983). peak spawning is then observed in spring or early summer, sometimes extended with more than one spawning peak (bayne 1976). this type of gametogenic cycle has been observed e.g. in western norway (barkati 1990), the faroe islands (thorarinsdóttir et al. unpubl. ms.), ireland (snodden & roberts 1997), wales (lowe et al. 1982), germany (sprung 1983), portugal (reis-henriques & coimbra 1990), the baltic (kautsky 1982) and the wadden sea (pieters et al. 1979). in long island sound, off the east coast of the united states, brousseau (1983) also observed a population with a similar pattern of gametogenesis. another pattern of the gametogenic cycle in m. edulis occurs when carbohydrate stores are limited and used for initiation of gonad development in winter but are not suffi cient for maturation of the gonads. the main growth of the gonads occurs in spring in conjunction with phytoplankton blooming and renewal of food resources and spawning occurs in late summer. this is the pattern found in the m. edulis populations in iceland and has also has been observed in populations in newfoundland (thompson 1984), eastern canada (newell et al. 1982) and off the west coast of the united states (emmet et al. 1987). the results from the present study indicate that the gametogenic cycles in the two mussels populations investigated were not the same. in mjoifjördur, gametogenesis was initiated in autumn but in january in breidifjördur. the temperature and food supply in autumn at the two sites were not signifi cantly different but the coming winter temperature in mjoifjördur was higher than in breidifjördur. the adaptation of the mussels to higher sea temperature in the winter might explain the onset of gametogenesis at this time of the year. in january, the gametogenesis speeded up in both populations in spite of low temperature and lack of food. possibly due to later onset of phytoplankton production, the development of the gametes in the mussels in mjöifjordur was slower in spring and the spawning started later in summer than in breidifjördur. as more information on mytilus edulis is gathered, it becomes clear that the traditional view of a single fi xed pattern of gametogenesis and spawning for a population is inadequate. rather, some fl exibility is shown with different adaptations to variations in environmental factors. acknowledgements.—we thank halldóra skarphéðinsdóttir for various help in planning and execution of the study. sigfús vilhjálmsson and ingólfur sigfússon collected samples of mussels and phytoplankton in mjoifjördur and hrönn hafsteinsdóttir collected the samples in breidifjördur—we are grateful to them. we also thank elena guijarro garcia and kristín valsdóttir for assistance in the laboratory and al kutzchera for preparing thin sections of gonads. thanks are also due to jørgen hylleberg for reading and improving the manuscript. references barkati, s. 1990: reproduction of the mussel mytilus edulis l. from lindåspollen, western norway. oebalia 1989– 1990 16, 1–14. bayne, b. l. 1975: reproduction in bivalve molluscs under environmental stress. in f. j. vernberg (ed.): physiological ecology of estuarine organisms. pp. 259–277. columbia, sc: university of south carolina press. bayne, b. l. 1976: aspects of reproduction in bivalve molluscs. in m. wiley (ed.): estuarine processes. vol. 1. uses, stresses and adaptation to the estuary. pp. 432–448. new york: academic press. brousseau, d. j. 1983: aspects of reproduction of the blue mussel, mytilus edulis (pelecypoda: mytilidae), in long island sound. fish. bull. 81, 733–739. chipperfi eld, p. n. j. 1953: observations on the breeding and settlement of mytilus edulis (l.) in british waters. j. mar. biol. assoc. u. k. 32, 449–476. emmett, b., thompson, k. & popham, j. d. 1987: the reproductive and energy storage cycles of two populations of 223thorarinsdóttir & gunnarsson 2003: polar research 22(2), 217–223 mytilus edulis (linne) from british columbia . j. shellfi sh res. 6, 29–36. fell, p. e. & balsamo a. m. 1985: recruitment of mytilus edulis l. in the thames estuary, with evidence for differences in the time of maximal settling along the connecticut shore. estuaries 8, 68–75. gabbott, p. a. 1983: development of seasonal metabolic activities in marine molluscs. in p. w. hochachka (ed .): the mollusca. vol. 2. environmental and biochemical physiology. pp. 165–217. new york: academic press. giese, a. a. 1959: comparative physiology: annual reproductive cycle of marine invertebrates. ann. rev. physiol. 21, 547–576. gray, a. p., seed, r. & richardson, c. a. 1997: reproduction and growth of mytilus edulis chilensis from the falkland islands. sci. mar. 61, 39–48. jeffrey, s. w. & humphrey, g. f. 1975: new spectrophotometric equations for determining chlorophylls a, b, c1 and c2 in higher plants, algae and natural phytoplankton. biochem. physiol. pfl anz. 167, 191–194. kautsky, n. 1982: quantitative studies on gonad cycle, fecundity, reproductive output and recruitment in a baltic mytilus edulis population. mar. biol. 68, 143–160. lowe, d. m., moore, m. m. & bayne, b. l. 1982: aspects of gametogenesis in the marine mussel mytilus edulis l. j. mar. biol. assoc. u. k. 62, 133–145. lubet, p. 1959: recherches sur le cycle sexuel et l´émission des gamètes chez les mytilides et les pectinides. rev. trav. inst. pêches marit. 23, 395–548. newell, r. i. e., hilbish, t. j., koehn, r. k. & newell, c. j. 1982: temporal variation in the reproductive cycle of mytilus edulis l. from localities on the east coast of the united states. biol. bull. 162, 299–310. parulekar, a. h., dalal, s. g., ansari, z. a. & harkantra, s. n. 1982: environmental physiology of raft-grown mussels in goa, india. aquaculture 29, 83–93. pieters, h., kluytmans, j. h., zurberg, w. & zandee, d. i. 1979: the infl uence of seasonal changes on energy metabolism in mytilus edulis (l). i. growth rate and biochemical composition in relation to environmental parameters and spawning. in e. naylor & r. h. hartnoll (eds.): cyclic phenomena in marine plants and animals. pp. 285–293. new york: pergamon press. reis-henriques, m. a. & coimbra, j. 1990: variations in the levels of progesterone in mytilus edulis during the annual reproductive cycle. comp. biochem. physiol. 95a, 343– 348. seed, r. 1969: the ecology of mytilus edulis l. on exposed rocky shores. i. breeding and settlement. oecologia (berlin) 3, 277–316. seed, r. 1976: ecology. in b. l. bayne (ed.): marine mussels: their ecology and physiology. pp. 13–65. cambridge: cambridge university press. seed, r. & brown, r. a. 1977: a comparison of the reproductive cycles of modiolus modiolus (l.) cerastoderma (= cardium) edule (l) and mytilus edulis (l) in strangford lough, northern ireland . oecologia (berlin) 30, 173–188. seed, r. & suchanek, t. h. 1992: population and community ecology of mytilus. in e. gosling (ed.): the mussel mytilus: ecology, physiology, genetics and culture. pp. 87– 196. london: elsevier. snodden, l. m. & roberts, d. 1997: reproductive patterns and tidal effects on spat settlement of mytilus edulis populations in dundrum bay, northern ireland. j. mar. biol. assoc. u. k. 77, 229–243. sprung, m. 1983: reproduction and fecundity of the mussel mytilus edulis at helgoland (north sea). helgol. meeresunters. 36, 243–255. starr, m., himmelman, j. h. & therriault, j. 1990: direct coupling of marine invertebrate spawning to phytoplankton blooms. science 247, 1071–1074. thompson, r. j. 1979: fecundity and reproductive effort in the blue mussel (mytilus edulis), the sea urchin (strongylocentrotus droebachiensis) and the snow crab (chionoecotes opilio) from populations in nova scotia and newfoundland. j. fish. res. board can. 36, 955–964. thompson, r. j. 1984: the reproductive cycle and physiological ecology of the mussel mytilus edulis in a subarctic, nonestuarine environment. mar. biol. 79, 277–288. thorarinsdóttir, g. g. 1996: gonad development, larval settlement and growth of mytilus edulis l. in a suspended population in hvalfjördur, south-west iceland. aquac. res. 27, 57–65. thorarinsdóttir, g. g., gunnarsson, k. & dam, m. unpubl. ms.: gonad development in mytilus edulis l. in the faroes. << /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /all /binding /left /calgrayprofile (dot gain 20%) /calrgbprofile (srgb iec61966-2.1) /calcmykprofile (u.s. web coated \050swop\051 v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.4 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo false /preserveopicomments false /preserveoverprintsettings true /startpage 1 /subsetfonts true /transferfunctioninfo /apply /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages true /colorimagedownsampletype /bicubic /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages true /grayimagedownsampletype /bicubic /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages true /monoimagedownsampletype /bicubic /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile () /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /fra <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> /enu (use these settings to create pdf documents with higher image resolution for improved printing quality. the pdf documents can be opened with acrobat and reader 5.0 and later.) /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308000200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e30593002537052376642306e753b8cea3092670059279650306b4fdd306430533068304c3067304d307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e30593002> /deu <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> /ptb <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> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [612.000 792.000] >> setpagedevice carlini.indd 139carlini et al. 2006: polar research 25(2), 139–144 haul-out pattern of itinerant male antarctic fur seals (arctocephalus gazella) at laurie island, south orkney islands alejandro r. carlini, gustavo a. daneri, ricardo casaux, maría e. i. márquez the seasonal haul-out pattern of itinerant male antarctic fur seals (arctocephalus gazella) was determined by regular counts at mossman peninsula, laurie island, south orkney islands, from 1996 to 2005. small numbers of animals began to arrive at the beach in late december / early january (mean date 28 december ± 15 days, n = 10). peak numbers of animals ashore changed considerably between seasons. in 1996, 1998 and 2001, peak numbers were registered in march (6/3, 18/3 and 6/3, respectively). numbers peaked in 1997, 1999 and 2005 at the end of january / beginning of february (26/1, 2/2 and 28/1, respectively). in 2000, 2002, 2003 and 2004 peaks were registered in the third week of february (15/2, 22/2, 14/2 and 20/2, respectively). peaks in numbers of seals ashore also varied between years, being minimum during 2001 (2531 individuals) and maximum during 2006 (16 610 individuals). in march 1998 the coasts of laurie island were surveyed by navigating infl atable boats near the shoreline; 18 haul-out places were identifi ed. the big differences in peak numbers, as well as in the dates of peak events among years, suggest that local conditions could have an effect on the numbers of animals hauled out in a given year. it may therefore be diffi cult to predict trends from summer censuses in non-breeding places. a. r. carlini, r. casaux & m. e. i. márquez, depto. de ciencias biológicas, instituto antártico argentino, cerrito 1248, c1010 aaz buenos aires, argentina, acarlini@dna.gov.ar; g. a. daneri, división mastozoología, museo argentino de cs. naturales “b. rivadavia”, av. angel gallardo 470, c1405 djr buenos aires, argentina. antarctic fur seals (arctocephalus gazella peters, 1875) were subjected to an extensive commercial harvest and nearly exterminated during the 19th and early 20th centuries (bonner 1968). since the cessation of sealing a substantial recovery of the population has taken place from small remnant breeding groups located around south georgia and bouvetøya (bouvet island) (bonner 1968; payne 1977; boyd 1993; wynen et al. 2000). at present, the main breeding locations are at bird island and at the western end of south georgia (boyd 1993), although breeding colonies have been re-established throughout the scotia arc and elsewhere (bengtson et al. 1990). there are no important breeding places in the south orkney islands, probably because the archipelago as a whole has too short an ice-free summer to allow successful breeding (kightley & caldwell 1982). laws (1981) identifi ed breeding colonies at monroe island, gosling islands and michelsen island, comprising around 100 pups. additionally, kightley & caldwell (1982) 140 haul-out pattern of itinerant male antarctic fur seals reported the fi rst birth on signy island in february 1987. total pups born in the archipelago were recently estimated to be less than 1000 (scar expert group on seals 2004). no breeding groups have been reported at laurie island and only four births have been recorded there. however, an important group of non-breeding adult and subadult males is present during the summer at this location (vergani & coria 1989). the work on which this paper is based was carried out at laurie island over 10 consecutive years. the study presents information on the haulout pattern of itinerant male antarctic fur seals at mossman peninsula and provides the results of the fi rst survey of the whole coast of the island. materials and methods the study was carried out at mossman peninsula, laurie island (60° 45' s, 44° 43' w), south orkney islands, from 1996 to 2005 (fig. 1). antarctic fur seals were counted weekly throughout the year by two observers on foot along the approximately 4 km of coast between the argentinean orcadas station and point martin (sites a, b, c, d, e on fig. 1). the same observers who counted the animals in one year trained, for about one month, two other observers for the following year. when groups had over 3000 seals, which generally occurred in site c for some seasons, three independent counts were made from a cliff and the average value was calculated. animals were not sorted into age classes but they were mainly adult and sub-adult males. between 6 and 13 march 1998 the coasts of laurie island were surveyed by navigating infl atable boats near the shoreline to identify additional haul-out places. since animals began to arrive in december, reports for a given year in this work include data from december of the previous year (i.e. the number of seals reported for 1996 includes december 1995). results and discussion small numbers of animals began to arrive at the beach in late december / early january (mean date 28 december ± 15 days, n = 10), and numbers started to increase from the second week fig. 1. haul-out places (grey dots) of itinerant antarctic fur seals (arctocephalus gazella) in march 1998 at laurie island, south orkney islands. a–e mark sites where weekly counts were made. 141carlini et al. 2006: polar research 25(2), 139–144 date date date date date date date date date date 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 n um be r of s ea ls n um be r of s ea ls n um be r of s ea ls n um be r of s ea ls n um be r of s ea ls n um be r of s ea ls n um be r of s ea ls n um be r of s ea ls n um be r of s ea ls n um be r of s ea ls 6/3 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 26/1 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 18/3 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 2/2 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 15/2 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 31 /7 28/1 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 31 /7 20/2 0 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 14/2 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 26/2 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 6/3 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 2000 4000 6000 8000 10000 12000 fig. 2. changes in the number of itinerant antarctic fur seals (arctocephalus gazella) present on the study beach at laurie island from 1996 to 2005. reports for a given year include data from december of the previous year. 142 haul-out pattern of itinerant male antarctic fur seals of january (fig. 2). the peak number of animals ashore varied among seasons (table 1, fig. 2). in 1996, 1998 and 2001, peak numbers were registered in march (6/3, 18/3 and 6/3, respectively). in 1997, 1999 and 2005 numbers peaked at the end of january / beginning of february (26/1, 2/2 and 28/1, respectively). in 2000, 2002, 2003 and 2004 peaks were registered in mid-february (15/2, 22/2, 14/2 and 20/2, respectively). the haul-out period for non-breeding antarctic fur seals was also reported for heard island by page et al. (2003), who observed that the number of sub-adult and adult males increased markedly from late january, with the highest numbers registered between 23 february and 9 march. similarly, at signy island (south orkney islands) the annual summer immigration amounted to 20 500 individuals, with peak numbers also occurring in february (smith 1997), while at marion island, maximum numbers of adult and sub-adult males occurred during the autumn moulting peak in march (kerley 1983). the dates of peak numbers in most years at laurie island (february–march) are similar to those found at the above-mentioned localities, which would be accounted for by animals coming ashore during their moulting period. however, in some years (1997, 1999, 2005) peak numbers of animals ashore occurred in late january / early february, although in these “atypical” years a second lower peak followed in february–march (table 1, fig. 2). between august and november, in some of the years, there were very few animals on the beach. for this period, maximum numbers occurred in october in 1996, 2001, 2003 and 2004 (37, 103, 27 and 34 fur seals, respectively), but in august in 1999. no fur seals were observed in 1997, 1998, 2000 or 2002 for the same period. total numbers of animals ashore at laurie island at peak haul-out varied enormously among years, with lowest numbers in 2001 (2531 animals) and a maximum in 2005 (16 610 animals) (fig. 3). such a variation in seals’ numbers could be related to an ocean wide event such as el niño–southern oscillation (enso). enso has a profound effect on the weather and oceanic conditions across the tropical pacifi c, where it has its origin. it has been suggested that the effects of enso might be transmitted from the tropical pacifi c ocean to the antarctic (turner 2004). this could cause changes in physical environmental variables, fi nally affecting the numbers of animals observed. we could not fi nd a clear connection between the number of seals at peak haul-out and enso. el niño events (1997/1998 and 2002/2003) or la niña events (1998/1999 and 2000/2001) involved seasons with 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 19 85 19 86 19 87 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 year n um be r o f s ea ls a t pe ak h au l-o ut fig. 3. numbers of antarctic fur seals (arctocephalus gazella) at peak haul-out. data for 1985–87 from vergani & coria (1989); data for 1996–2005 from this study. table 1. dates and numbers of itinerant arctocephalus gazella at peak haul-out from 1996 to 2005 at mossman peninsula, laurie island. year main peak event date numbers 1996 6 march 5559 1997 26 january 11 577 1998 18 march 4163 1999 2 february 5778 2000 15 february 9368 2001 6 march 2531 2002 26 february 7635 2003 14 february 5160 2004 20 february 7164 2005 28 january 16 610 143carlini et al. 2006: polar research 25(2), 139–144 similar numbers of seals at laurie island at peak haul-out (table 1, fig. 2). considering the previous census in the area (vergani & coria 1989), it seems likely that there has been an increase in the numbers of antarctic fur seals that haul out on the beaches in the study area (fig. 3). however, the big inter-annual differences in numbers together with the variations in the peak dates, support the idea that local conditions, with their potential effects on food availability in the area, could have an effect on the numbers of animals hauled out in a given year. it may therefore be diffi cult to predict trends from summer censuses in non-breeding places. a total of 18 haul-out places were identifi ed from the survey of the laurie island coast in march 1998 (fig. 1). because observers were not able to land to count seals, we lack accurate estimates of animals at these sites. nevertheless, it was possible to observe that site c at mossman peninsula shelters the biggest haul-out place at laurie island, while the second largest concentration of animals was identifi ed at site f (fig. 1). fur seals at laurie island are probably immigrants from south georgia (kightley & cadwell 1982), which is home to the largest fur seal population and accounts for around 95 % of total pup production for the species (boyd 1993), with the current population estimated at over three million individuals (barlow et al. 2002). available data from south georgia indicate an annual increase in pup production of 16.8 % from 1957 to 1972 (payne 1977) and 9.8 % from 1976 to 1990, as well as an expansion of the breeding range (boyd 1993). it has been suggested that a possible reason for the decline in the annual increase in the south georgia population is that emigration is taking place from the traditional breeding sites, some of which have reached their capacity (boyd 1993). the south orkney islands are similar to south georgia in that high densities of krill can be found nearby (everson & goss 1991; kasatkina et. al 1997). availability of krill is a critical factor in determining breeding locations, since fur seals depend on rich localized food resources, especially during lactation (costa 1991). in spite of this, only four pups were born at the study site on laurie island over the 10-year study period, suggesting that the south coasts of laurie island are not suitable breeding areas for the species, probably because they are often covered by ice until december. coincidentally, a survey of antarctic fur seals in the south shetland islands indicated that no pupping sites were located on the southern coasts of these islands along the bransfi eld strait (bengtson et al. 1990). according to these authors, the absence of pups on these coasts would suggest that newly occupied pupping sites may be vulnerable to disturbance (e.g. human, climatic factors) until a traditional pupping site is established and the rookery has become suffi ciently large and socially stable to persist and grow. this explanation would fi t well to the phenomenon observed at laurie island. acknowledgements.—we would like to express our gratitude to the staff of the administración de parques nacionales: r. cerda, s. vellido, e. luoni, o. jensen, a. georgópulos, c. quintana, r. zalazar, m. calvi, r. cerdá, m. gray, g. willink, a. seuferheld, a. sanchez, f. ferioli, g. porro, g. sanchez, g. carreras, p. rosso, a. dalmasso, r. amado, a. beati, d. saad and e. rombola for fi eld assistance. we thank the members of the orcadas station for their logistic support. we want to thank two anonymous reviewers for their helpful comments on the manuscript. references barlow, k. e., boyd, i. l., croxall, j. p., reid, k., staniland, i. j. & brierley, a. s. 2002: are penguins and seals in competition for antarctic krill at south georgia? mar. biol. 140, 205–213. bengtson, j. l., ferm, l. m., härkönen, t. j. & stewart, b. s. 1990: abundance of antarctic fur seals in the south shetland islands, antarctica, during the 1986/87 austral summer. in k. kerry & g. hempel (eds.): antarctic ecosystems: ecological change and conservation. pp. 265–270. springer: new york. bonner, w. n. 1968: the fur seals of south georgia. br. antarct. surv. sci. rep. 56. boyd, i. 1993: pup production and distribution of breeding antarctic fur seals (arctocephalus gazella) at south georgia. antarct. sci. 5, 17–24. costa, d. p. 1991: reproductive and foraging energetics in pinnipeds: implications for life history patterns. in d. renouf (ed.): behaviour of pinnipeds. pp. 300–344. london: chapman & hall. everson, i. & goss, c. 1991: krill fi shing activity in the southwest atlantic. antarct. sci. 3, 351–358. kasatkina, s. m., shnar, m. i., polischuk, m. i., abramov, a. m. & sushin, v. a. 1997: assessment of krill fl ux factors in waters of the south orkney islands during summer 1996. ccamlr sci. 4, 195–204. kerley, g. i. h. 1983: comparison of seasonal haul-out patterns of fur seals arctocephalus tropicalis and a. gazella on subantarctic marion island. s. afr. j. wildl. res. 13, 71–77. kightley, p. j. & caldwell, j. r. 1982: the fi rst record of a fur seal birth on signy island, south orkney islands. br. ant144 haul-out pattern of itinerant male antarctic fur seals ery. in b. bataglia et al. (eds.): antarctic communities, species, structure and survival. pp. 432–436. cambridge: cambridge university press. turner, j. 2004: the el niño–southern oscillation and antarctica. int. j. climatol. 24, 1–31. vergani, d. f. & coria, r. 1989: increase in numbers of male fur seals arctocephalus gazella during the summer– autumn period at mossmann peninsula (laurie island). polar biol. 9, 487–488. wynen, l. p., goldsworthy, s. d., guinet, c., bester, m. n., boyd, i. l., gjertz, i., hofmeyr, g. j. g., white, r. w. g. & slade, p. r. 2000: postsealing genetic variation and population structure of two species of fur seal (arctocephalus gazella and a. tropicalis). mol. ecol. 9, 299–314. arct. surv. sci. rep. 51, 287–289. laws, r. m. 1981: seal surveys, south orkney islands, 1971 and 1974. br. antarct. surv. bull. 54, 136–139. page, b., welling, a., chambellant, m., goldsworthy, s. d., dorr, t. & van veen, r. 2003: population status and breeding season chronology of herd island fur seals. polar biol. 26, 219–224. payne, m. r. 1977: growth of a fur seal population. philos. trans. r. soc. lond. b 279, 67–79. scar expert group on seals 2004: status of stocks. tromsø. accessed on the internet at www.seals.scar.org/pdf/ statusofstocs.pdf. smith, r. i. l. 1997: impact of an increasing fur seal population on antarctic plant communities: resilience and recov<< /ascii85encodepages false /allowtransparency false /autopositionepsfiles true /autorotatepages /none /binding /left /calgrayprofile (dot gain 10%) /calrgbprofile (apple rgb) /calcmykprofile (u.s. sheetfed coated v2) /srgbprofile (srgb iec61966-2.1) /cannotembedfontpolicy /warning /compatibilitylevel 1.3 /compressobjects /tags /compresspages true /convertimagestoindexed true /passthroughjpegimages true /createjdffile false /createjobticket false /defaultrenderingintent /default /detectblends true /colorconversionstrategy /leavecolorunchanged /dothumbnails false /embedallfonts true /embedjoboptions true /dscreportinglevel 0 /syntheticboldness 1.00 /emitdscwarnings false /endpage -1 /imagememory 1048576 /lockdistillerparams false /maxsubsetpct 100 /optimize true /opm 1 /parsedsccomments true /parsedsccommentsfordocinfo true /preservecopypage true /preserveepsinfo true /preservehalftoneinfo true /preserveopicomments true /preserveoverprintsettings true /startpage 1 /subsetfonts false /transferfunctioninfo /preserve /ucrandbginfo /preserve /useprologue false /colorsettingsfile () /alwaysembed [ true ] /neverembed [ true ] /antialiascolorimages false /downsamplecolorimages false /colorimagedownsampletype /average /colorimageresolution 300 /colorimagedepth -1 /colorimagedownsamplethreshold 1.50000 /encodecolorimages true /colorimagefilter /dctencode /autofiltercolorimages true /colorimageautofilterstrategy /jpeg /coloracsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /colorimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000coloracsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000colorimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasgrayimages false /downsamplegrayimages false /grayimagedownsampletype /average /grayimageresolution 300 /grayimagedepth -1 /grayimagedownsamplethreshold 1.50000 /encodegrayimages true /grayimagefilter /dctencode /autofiltergrayimages true /grayimageautofilterstrategy /jpeg /grayacsimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /grayimagedict << /qfactor 0.15 /hsamples [1 1 1 1] /vsamples [1 1 1 1] >> /jpeg2000grayacsimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /jpeg2000grayimagedict << /tilewidth 256 /tileheight 256 /quality 30 >> /antialiasmonoimages false /downsamplemonoimages false /monoimagedownsampletype /average /monoimageresolution 1200 /monoimagedepth -1 /monoimagedownsamplethreshold 1.50000 /encodemonoimages true /monoimagefilter /ccittfaxencode /monoimagedict << /k -1 >> /allowpsxobjects false /pdfx1acheck false /pdfx3check false /pdfxcompliantpdfonly false /pdfxnotrimboxerror true /pdfxtrimboxtomediaboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxsetbleedboxtomediabox true /pdfxbleedboxtotrimboxoffset [ 0.00000 0.00000 0.00000 0.00000 ] /pdfxoutputintentprofile (none) /pdfxoutputcondition () /pdfxregistryname (http://www.color.org) /pdfxtrapped /unknown /description << /jpn <feff3053306e8a2d5b9a306f30019ad889e350cf5ea6753b50cf3092542b308030d730ea30d730ec30b9537052377528306e00200050004400460020658766f830924f5c62103059308b3068304d306b4f7f75283057307e305930023053306e8a2d5b9a30674f5c62103057305f00200050004400460020658766f8306f0020004100630072006f0062006100740020304a30883073002000520065006100640065007200200035002e003000204ee5964d30678868793a3067304d307e305930023053306e8a2d5b9a306b306f30d530a930f330c8306e57cb30818fbc307f304c5fc59808306730593002> /fra <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> /deu <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> /ptb <feff005500740069006c0069007a006500200065007300740061007300200063006f006e00660069006700750072006100e700f5006500730020007000610072006100200063007200690061007200200064006f00630075006d0065006e0074006f0073002000500044004600200063006f006d00200075006d00610020007200650073006f006c007500e700e3006f00200064006500200069006d006100670065006d0020007300750070006500720069006f0072002000700061007200610020006f006200740065007200200075006d00610020007100750061006c0069006400610064006500200064006500200069006d0070007200650073007300e3006f0020006d0065006c0068006f0072002e0020004f007300200064006f00630075006d0065006e0074006f0073002000500044004600200070006f00640065006d0020007300650072002000610062006500720074006f007300200063006f006d0020006f0020004100630072006f006200610074002c002000520065006100640065007200200035002e00300020006500200070006f00730074006500720069006f0072002e00200045007300740061007300200063006f006e00660069006700750072006100e700f50065007300200072006500710075006500720065006d00200069006e0063006f00720070006f0072006100e700e3006f00200064006500200066006f006e00740065002e> /dan <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> /nld <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> /esp <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> /suo <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> /ita <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> /nor <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> /sve <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> /enu <feff002000500044004600200069006e006e007300740069006c006c0069006e00670065007200200066006f00720020004f00660066007300650074007400720079006b006b0069006e006700200068006f00730020004c0075006e00640062006c006100640020004d006500640069006100200041005300200034002e00310032002e00300033> >> >> setdistillerparams << /hwresolution [2400 2400] /pagesize [595.276 822.047] >> setpagedevice polar research 2019. © 2019 e. fuglei & a. tarroux. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. citation: polar research 2019, 38, 3512, http://dx.doi.org/10.33265/polar.v38.3512 1 (page number not for citation purpose) r e s e a r c h a r t i c l e arctic fox dispersal from svalbard to canada: one female’s long run across sea ice eva fuglei1 & arnaud tarroux2 1norwegian polar institute, fram centre, tromsø, norway; 2department of arctic ecology, norwegian institute for nature research, fram centre, tromsø, norway introduction on the sea ice on 26 april 1885 at 85°n, during his expedition to the north pole, the explorer fridtjof nansen noted: “i was not a little surprised yesterday morning when i suddenly saw the track of an animal in the snow. it was that of an arctic fox […]. the trail was quite fresh. what in the world was that fox doing up here out on the wild sea?” (nansen 1897: 294). the arctic fox (vulpes lagopus) has become known for its exceptional mobility and endurance in barren polar environments ( chesemore 1968; wrigley & hatch 1976; eberhardt & hanson 1978; eberhardt et al. 1983) and tentative answers to nansen’s question have been offered by several generations of arctic fox researchers. arctic fox excursions on sea ice were early on explained as seasonal foraging trips (chesemore 1968; garrott & eberhardt 1987). such behaviour could be sparked by polar bears (ursus maritimus) making carrion available on sea ice (smith 1980; lydersen  &  gjertz  1986), or seasonal or annual scarcity of key terrestrial resources such as migrating birds, lemmings or carcasses of larger mammals (braestrup 1941; wrigley & hatch 1976). however, ear-tagged arctic foxes have provided evidence for movements over sea ice exceeding 1000 km (chesemore 1968; wrigley & hatch 1976; eberhardt & hanson 1978; eberhardt et al. 1983), beyond what could be expected from occasional foraging trips from breeding home ranges. in the last 20 years, satellite telemetry in north america has revealed heretofore uknown details of the spatial ecology of arctic foxes (follmann & martin 2000; pamperin et al. 2008; tarroux et al. 2010; lai et al. 2015; rioux et al. 2017). such studies have demonstrated the extensive use of sea ice as a foraging habitat and as a platform for exploration and dispersal. understanding what triggers movements of animals from the birth place to a potential breeding place (natal dispersal), or from one breeding place to another (breeding dispersal), is important for abstract we report the first satellite tracking of natal dispersal by an arctic fox (vulpes lagopus) between continents and high-arctic ecosystems. a young female left spitsbergen (svalbard archipelago, norway) on 26 march 2018 and reached ellesmere island, nunavut, canada, 76 days later, after travelling a cumulative distance of 3506 km, bringing her ca. 1789 km away (straight-line distance) from her natal area. the total cumulative distance travelled during the entire tracking period, starting when she left her natal area on 1 march 2018 and ending when she settled on ellesmere island on 1 july 2018, was 4415 km. this is among the longest dispersal events ever recorded for an arctic fox. crossing extensive stretches of sea ice and glaciers, the female moved at an average rate of 46.3 km/day ± 41.1 sd. the maximum movement rate was 155 km/day and occurred on the ice sheet in northern greenland. this is the fastest movement rate recorded for this species. the northernmost location recorded was on the sea ice off northern greenland at a latitude of 84.7°n. the arctic fox was of the blue colour morph typical for coastal environments, where arctic foxes are adapted to food webs without lemmings but with substantial inputs of marine food resources. the arctic fox settled on ellesmere island in a food web with lemmings, thereby switching ecosystems. our observation supports evidence of gene flow across arctic regions, including those seasonally bridged by sea ice, found in studies of the circumpolar genetic structure of arctic fox populations. keywords argos satellite tracking; blue morph; coastal fox; lemming fox; large-scale movements; vulpes lagopus correspondence eva fuglei, norwegian polar institute, fram centre, po box 6606 langnes, no-9296 tromsø, norway. e-mail: eva.fuglei@npolar.no abbreviations amsr2: advanced microwave scanning radiometer 2; sd: standard deviation http://creativecommons.org/licenses/by-nc/4.0/� http://dx.doi.org/10.33265/polar.v38.3512� mailto:eva.fuglei@npolar.no citation: polar research 2019, 38, 3512, http://dx.doi.org/10.33265/polar.v38.35122 (page number not for citation purpose) arctic fox dispersal from svalbard to canada e. fuglei & a. tarroux the study of population dynamics and the distribution of species (clobert et al. 2001). there is a large literature on what drives dispersal in animals. profound spatial and temporal variability in population density and resource abundance are considered to be particularly forceful drivers of dispersal (ims & hjermann 2001). the arctic fox is generally classified into two ecotypes: “coastal fox” and “lemming fox” (braestrup 1941). the coastal ecotype lives on arctic islands without lemmings (lemmus and dicrostonyx spp.) and largely relies on food sources from the marine food web (prestrud 1992; hersteinsson & macdonald 1996; ehrich et al. 2015). the coastal ecotype is most typically represented by a dark (“blue”) colour morph, reflecting that the foxes are often moving against a dark ground in regions with iceand snow-free coastlines in winter (fuglei & ims 2008). the lemming ecotype (predominantly of the white colour morph) is heavily dependent on cyclic peaks of lemming populastions for successful breeding, but may shift to other terrestrial or marine resources in years of low lemming abundance (bêty et al. 2002; roth 2002; angerbjörn et al. 2004; ehrich et al. 2015). it has been suggested that long-distance movements and nomadic behaviour are more common in the lemming ecotype than in the coastal ecotype (braestrup 1941; pullainen 1965; wrigley & hatch 1976; pamperin et al. 2008; tarroux et al. 2010; norén et al. 2011; lai et al. 2017). the low food availability and higher fox population densities after a lemming peak may generate high levels of intraspecific competition, triggering dispersal (roth 2002; lai et al. 2015). the few published records of arctic fox movements based on satellite telemetry stem from ecosystems with lemmings in north america (pamperin et al. 2008; tarroux et al. 2010; lehner 2012; lai et al. 2017). centrally located in the polar basin, the norwegian archipelago of svalbard is seasonally linked to greenland and north america by sea ice that offers a potential means for long-distance dispersal for the islands’ arctic foxes. however, evidence for such movements has been only indirect up to now, in the form of genetic analyses. here we report on a young female arctic fox—part of a larger and ongoing study of arctic fox spatial ecology in svalbard—that travelled from svalbard to ellesmere island, nunavut, canada, during a few months in spring 2018. methods study area the arctic fox reported on here was part of a study (n = 54) that started in 2012 on the west coast of spitsbergen, the largest island in the high-arctic svalbard archipelago (74° – 81°n, 10° – 30°e). a female arctic fox of the blue colour morph was captured on 29 july 2017, probably close to her natal den near the front of the glacier fjortende julibreen (79°06’n and 11°52’e), in krossfjorden. we used two trapping methods in the study: a swiss-snare system consisting of a spring-mounted plastic-coated foot snare (nybakk et al. 1996; eide et al. 2004) mounted on a modified padded leg-hold trap system (victor no. 1 softcatch® padded leg-hold trap); and a tomahawk live trap (100 × 30 × 30 cm). the fox discussed in this paper was caught in a cage trap. during the study, traps were continuously observed from a distance of 250 to 400 m through a telescope or binoculars, and when the female fox was trapped she was removed from the trap within five minutes. the fox was sexed, weighed (1900 g) and her age class estimated on the basis of her tooth wear (juvenile). she was then outfitted with a 115-g kiwisat 303 argos platform transmitter (cls 2016; biotrack ltd.) satellite tracking, data filtering and processing environmental data the satellite collar transmitted daily for a three-hour period between 14:00 and 17:00 gmt with a repetition rate of 60 seconds. we removed positions for which the location processed had failed (location class “z”; cls 2011) before applying a bayesian state-space model (jonsen et al. 2005; jonsen 2016) to filter the data and obtain a single position per day. filtering was done with the fit_ssm function from the bsam package (jonsen et al. 2005; jonsen 2016), using a first-difference correlated random walk with burn-in = 50  000 and sample size = 500 000, thinned by 100. daily gridded amsr2 sea-ice data resampled at a resolution of 3.25 km (spreen et al. 2008) were retrieved from the university of bremen’s sea ice remote sensing website (https://seaice. uni-bremen.de/start/data-archive/). topographic data were extracted from the general bathymetric chart of the oceans (gebco 2019). data processing, analysis and mapping were performed in r.3.5.1 (r development core team 2018). data were projected in polar stereographic projection with 75°n as standard parallel and 0° as central meridian, using functions available from sp and raster packages (bivand et al. 2008; hijmans 2018). average daily movement rates (km/day) were calculated assuming linear movements between successive locations and therefore correspond to minimum distances covered daily. results and discussion the tracking period presented here lasted exactly four months, that is, from 1 march 2018 to 1 july 2018. http://dx.doi.org/10.33265/polar.v38.3512� https://seaice.uni-bremen.de/start/data-archive/� https://seaice.uni-bremen.de/start/data-archive/� citation: polar research 2019, 38, 3512, http://dx.doi.org/10.33265/polar.v38.3512 3 (page number not for citation purpose) e. fuglei & a. tarroux arctic fox dispersal from svalbard to canada during that entire period, the young female arctic fox covered a total cumulative distance of 4415 km, representing a straight-line distance of 1789 km between her natal area and her position on 1 july 2018 (fig. 1; see also the supplementary animation). the short span of time spent covering such a distance highlights the exceptional movement capacity of this small-sized carnivore species. this journey was inter-continental in that the fox travelled from svalbard, in europe, to ellesmere island, in north america. a similar travelling distance was reported for an adult female arctic fox within the canadian arctic that travelled 4599 km, but over a longer period of 5.5 months (tarroux et al. 2010). like the canadian case, the svalbard fox used sea ice extensively to bridge distant regions (pamperin et al. 2008; tarroux et al. 2010; lehner 2012). from the date the svalbard fox was outfitted with a satellite transmitter, on 29 july 2017, and until approximately 1 march 2018, she stayed in a ca. 30 × 80 km area along the coastline of western spitsbergen (fuglei & tarroux, unpubl. data). she first moved to the northeast of spitsbergen and reached the ice-free shore on 11  march 2018 (fig. 1; supplementary animation). she then changed course and headed west, reaching the shore, where she again met open water on 16 march 2018 (fig. 1; supplementary animation). there the arctic fox turned again, heading south-east and crossing the northern part of spitsbergen from west to east, where, on 26 march 2018, she met ice-covered sea for the first time and left spitsbergen (figs. 1, 2), heading north-east on the sea ice. one day later, her route turned northward and then westward, towards north greenland, which fig. 1 large-scale movements of a young female arctic fox from svalbard tracked through argos satellite telemetry from 1 march to 1 july 2018 (date of passage is indicated at several locations along the track). the black dots represent the daily locations, and the colour of the segments linking successive locations indicates the daily movement rate. the sea-ice data show the concentration on 2 april 2018. sea-ice data retrieved from https://seaice. uni-bremen.de/data/ (spreen et al. 2008). map projection is polar stereographic (epsg3996). for an animated version of this map, see the supplementary animation. http://dx.doi.org/10.33265/polar.v38.3512� https://doi.org/10.6084/m9.figshare.8288159.v1 https://doi.org/10.6084/m9.figshare.8288159.v1 https://doi.org/10.6084/m9.figshare.8288159.v1 https://doi.org/10.6084/m9.figshare.8288159.v1 https://doi.org/10.6084/m9.figshare.8288159.v1 https://doi.org/10.6084/m9.figshare.8288159.v1 https://doi.org/10.6084/m9.figshare.8288159.v1 citation: polar research 2019, 38, 3512, http://dx.doi.org/10.33265/polar.v38.35124 (page number not for citation purpose) arctic fox dispersal from svalbard to canada e. fuglei & a. tarroux she reached 21 days (16 april 2018) and 1512 km after having left spitsbergen. she finally reached ellesmere island, nunavut, canada, 76 days (10 june 2018) after leaving spitsbergen. here she stayed in a limited area around the fosheim peninsula, until the satellite transmitter stopped transmitting on 6 february 2019 (fuglei & tarroux, unpubl. data). as the journey documented here transferred the young female fox from a natal home range (in spitsbergen) to a new terrestrial home range (on ellesmere island), it fits the definition of natal dispersal (clobert et al. 2001). the fox’s average movement rate varied greatly throughout the journey from spitsbergen to ellesmere, with a mean of 46.3 km/day (±41.1 sd; table 1, fig. 3) and peaking at 155 km/day (fig. 2). this is, to our knowledge, the fastest movement rate ever recorded for this species, 1.4 times faster than the maximum rate recorded in the previously reported long-distance movement of an adult male arctic fox in alaska (113 km/day; lehner 2012). the female travelled most quickly while crossing the ice sheet in north-western greenland (fig. 1). her average movement rate was higher by 34.0 km/day (95%  ci = [16.5; 51.5]) when travelling on sea ice than when travelling on land (fig. 3), suggesting that sea ice was used predominantly as a platform for dispersal, rather than as a foraging habitat. although fig. 3 does not discriminate between tundra and glacier (i.e., both are considered land), fig. 1 shows that the arctic fox also travelled rapidly when moving over the greenland ice sheet, a habitat that cannot offer many foraging opportunities. despite a high average movement rate on the sea ice, the movement rate dropped below 10 km/day for 48 hours on two occasions (7–8 april and 10–11 april; figs. 1, 2). such short stopovers might indicate physical barriers on the sea ice, bad weather or the occurrence of a food source; observing fox tracks by ice leads, nansen table 1 summary of the movement parameters of a young satellite-tracked female arctic fox dispersing from svalbard, norway, to ellesmere island, nunavut, canada. movement parameters leave spitsbergen 26 march 2018 arrive greenland 16 april 2018 leave greenland 6 june 2018 arrive ellesmere 10 june 2018 maximum straight-line distancea from origin 1789 km total tracking period (1 march to 1 july) time elapsed 122 days cumulative distance travelledb 4415 km spitsbergen to greenland time elapsed 21 days cumulative distance travelledb 1512 km spitsbergen to ellesmere time elapsed 76 days cumulative distance travelledb 3507 km mean movement rate (range) 46.3 (0.5–155.1) km/day astraight-line distance means the distance “as the crow flies” between two geographical points. bdistance travelled means the cumulated distance over successive locations along the path. fig. 3 boxplot of the daily movement rates of a young female arctic fox when on land and on sea ice. the horizontal bars represent the median, the boxes show the interquartile (25–75% percentiles) and the whiskers show the whole range. only locations during the journey from spitsbergen to ellesmere island (n = 76), between 26 march and 10 june 2018, are considered here. fig. 2 daily movement rates (red line) and straight-line distance from the point of departure (distance from origin; grey dashed line) at each location along the path of a young female arctic fox. the blue shaded bars indicate the sea-ice concentration when the fox was travelling on sea ice. the two black arrows indicate two short stopovers (7–8 and 10–11 april) on the sea ice between svalbard and greenland (fig. 1). http://dx.doi.org/10.33265/polar.v38.3512� citation: polar research 2019, 38, 3512, http://dx.doi.org/10.33265/polar.v38.3512 5 (page number not for citation purpose) e. fuglei & a. tarroux arctic fox dispersal from svalbard to canada (1897) speculated that the animals could snap up crustaceans from the open water. the sea ice at the location where the fox had the two stopovers is dynamic, with frequent lead formations that are characteristic for the pack ice north of svalbard (assmy et al. 2017). the leads act as biological hot spots attractive to amphipods, seabirds and marine mammals (assmy et al. 2017), such as ringed seal (pusa hispida), hooded seals (cystophora cristata), narwhal (monodon monoceros) and bowhead whale (balaena mysticetus; wiig et al. 1999; laidre & heide-jørgensen 2011; vacquie-garcia, lydersen, biuw et al. 2017; vacquie-garcia, lydersen, marques et al. 2017). lai et al. (2015) suggested that arctic foxes can detect a resource hotspot, like marine carrion, on the sea ice as much as 40 km away. sea-ice leads may offer a travelling fox a meal, but they may also constitute physical barriers several hundred metres wide, opening and refreezing over the course of a few days (weeks 2010), which is another potential explanation for the stopovers. alternatively, a blizzard or other adverse weather forced the fox to find shelter until conditions improved. this female fox’s journey offers an answer to nansen’s conjecture about the evidence he saw of arctic foxes on the sea ice at 85°n: “can they have gone astray?” he wondered (1897: 156). arctic foxes observed far north on the ice-covered arctic ocean are likely engaged in long distance dispersal rather than astray. population genetic studies have shown that there is extensive gene flow among arctic fox populations across all arctic islands and continents that are connected with sea ice (carmichael et al. 2007; geffen et al. 2007; norén et al. 2011). this is most likely the result of individuals dispersing between distant populations. norén et al. (2011) used population genetic analyses to infer that the immigration rate is higher than the emigration rate in svalbard and that arctic foxes in svalbard immigrate from lemming-dominated ecosystems in north america and siberia. this is in line with the suggestion that long-distance movements are more common among the lemming ecotype (low food availability after a lemming peak acting as a dispersal trigger) than in the coastal ecotype (braestrup 1941; pullainen 1965; wrigley & hatch 1976; roth 2002; pamperin et al. 2008; tarroux et al. 2010; norén et al. 2011; lai et al. 2015; rioux et al. 2017). there is limited evidence to suggest that in some den areas in svalbard some adult offspring may remain in their natal areas to help rear siblings (norén et al. 2012). more research is required to confirm this. if it is the case, it would be a factor reducing the dispersal rate. the case of the female arctic fox reported herein, as well as the emigration of an ear-tagged arctic fox from ny-ålesund, svalbard (78°55′n, 11°56′e), that was shot some 1200 km away in the russian archipelago of novaya zemlya (fuglei & øritsland 2003), suggests that although lower dispersal rates may be expected in the relatively more stable food webs experienced by coastal foxes in svalbard, they still perform occasional longdistance dispersals that may be triggered by food shortages lasting for several weeks in winter ( prestrud 1992). however, we cannot make strong inferences about population-level emmigration rates based on one or two documented dispersal events. we must also keep in mind that long-distance natal dispersal can be expected to take place even in stable environments (hamilton & may 1977). according to analyses of population genetics, circumpolar connectivity has been maintained among arctic fox populations across most of the species’ distribution range, likely because sea ice serves as a bridge linking distant populations. consequently, there are very few isolated arctic fox populations (carmichael et al. 2007; geffen et  al. 2007; norén et al. 2011). rapid warming in the arctic may change this (gaston et al. 2012). in the waters around svalbard, the general decline of sea-ice extent has already been reported to be affecting the spatial ecology of several species of sea mammals (hamilton et al. 2015; hamilton et al. 2017; vacquie-garcia et al. 2018). if svalbard becomes ice-free throughout the year, it will imply an isolated arctic fox population there, entirely cut off from other arctic foxes, such fox populations may still be highly viable, as they are in iceland (hersteinsson & macdonald 1996) and the beringian islands (volodin et al. 2013), where isolated arctic fox populations persist in a substantially warmer climate. acknowledgements methods used to trap and handle animals in our study were carried out in accordance with the principles and guidelines of the norwegian animal welfare act, with permission from the national animal research authority of norway. permits for conducting the fieldwork were obtained from the governor of svalbard. we thank t. sandal, e. strømseng and a.m. strømseng for participating in the fieldwork; c. helgeland and m. andersen for help with downloading, formatting and archiving the argos tracking data; h.d. jølle for assistance with the nansen references; and r.a. ims, g. samelius and one anonymous reviewer for constructive comments on the manuscript. funding the study was financially supported through the climate–ecological observatory for arctic tundra project and by the norwegian polar institute, including through the http://dx.doi.org/10.33265/polar.v38.3512� citation: polar research 2019, 38, 3512, http://dx.doi.org/10.33265/polar.v38.35126 (page number not for citation purpose) arctic fox dispersal from svalbard to canada e. fuglei & a. tarroux institute’s centre for ice climate and ecosystems. at was supported by the norwegian institute for nature research. disclosure statement the authors report no conflict of interest. references angerbjörn a., hersteinsson p. & tannerfeldt m. 2004. arctic foxes. consequences of resource predictability in the arctic fox—two life history strategies. in d.w. macdonald & c. sillero-zubiri (eds.): biology and conservation of wild canids. pp. 163–172. oxford: oxford university press. assmy p., fernández-méndez m., duarte p., meyer a., randelhoff a., mundy c.j., olsen l.m., kauko h.m., bailey a., chierici m., cohen l., doulgeris a.p., ehn j.k., fransson a., gerland s., hop h., hudson s.r., hughes n., itkin p., johnsen g., king j.a., koch b.p., koenig z., kwasniewski s., laney s.r., nicolaus m., pavlov a.k., polashenski c.m., provost c., rösel a., sandbu m., spreen g., smedsrud l.h., sundfjord a., taskjelle t., tatarek a., wiktor j., wagner p.m., wold a., steen h. & granskog m.a. leads in arctic pack ice enable early phytoplankton blooms below snow-covered sea ice. scientific reports 7, article no. 40850, http://dx.doi.org/10.1038/ srep40850. bêty j., gauthier g., korpimäki e. & giroux j.-f. 2002. shared predators and indirect trophic interactions: lemming cycles and arctic-nesting geese. journal of animal ecology 71, 88–98, http://dx.doi.org/10.1046/j.0021-8790.2001.00581.x. bivand r.s., pebesma e.j. & gómez-rubio v. 2008. applied spatial data analysis with r. new york: springer. braestrup f.w. 1941. a study of the arctic fox in greenland. immigrations, fluctuations in numbers based mainly on trading statistics. meddelelser om grønland 131(4). copenhagen: c.a. reitzels, commission for scientific investigations in greenland. carmichael l.e., krizan j., nagy j.a., fuglei e., dumond m., johnson d., veitch a., berteaux d. & strobeck c. 2007. historical and ecological determinants of genetic structure in arctic canids. molecular ecology 16, 3466–3483, http:// dx.doi.org/10.1111/j.1365-294x.2007.03381.x. chesemore d.l. 1968. notes on the food habits of the arctic foxes in northern alaska. canadian journal of zoology 46, 1127–1130, http://dx.doi.org/10.1139/z68-161 clobert j., danchin e., dhondt a.a. & nichols j.d. 2001. dispersal. new york: oxford university press. cls (collecte localisation satellites) 2016. argos user’s manual. largo, md: cls america. eberhardt l.e., garrot r.a. & hanson w.c. 1983. winter movements of arctic foxes, alopex lagopus, in a petroleum development area. canadian field-naturalist 97, 66–70, http://dx.doi.org/10.2307/1380754 eberhardt l.e. & hanson w.c. 1978. long-distance movements of arctic foxes tagged in northern alaska. canadian field-naturalist 92, 386–389. ehrich d., ims r.a., yoccoz n.g., lecomte n., killengreen s.t., fuglei e., rodnikova a.y., ebbinge b.s., menyushina i.e., nolet b.a., pokrovsky i.g., popov i.y., schmidt n.m., sokolov a.a., sokolova n.a. & sokolov v.a. 2015. what can stable isotope analysis of top predator tissues contribute to monitoring of tundra ecosystems? ecosystems 18, 404–416, http://dx.doi.org/10.1007/s10021-014-9834-9. eide n.e., jepsen j.u. & prestrud p. 2004. spatial organization of reproductive arctic foxes alopex lagopus: responses to changes in spatial and temporal availability of prey. journal of animal ecology 73, 1056–1068, http://dx.doi. org/10.1111/j.0021-8790.2004.00885.x. follmann e.h. & martin p. 2000. feasibility of tracking arctic foxes in northern alaska using the argos satellite system: preliminary results. biotelemetry 15, 368–374. fuglei e. & ims r.a. 2008. global warming and effects on the arctic fox. science progress 91, 175–191, http://dx.doi.org/ 10.3184/003685008x327468 fuglei e. & øritsland n.a. 2003. energy cost of running in an arctic fox (alopex lagopus). canadian field-naturalist 117, 430–435, http://dx.doi.org/10.22621/cfn.v117i3.746. garrott r.a. & eberhardt l.e. 1987. arctic fox. in m. novak et al. (eds.): wild furbearer management and conservation in north america. pp. 394–406. toronto: ontario ministry of natural resources. gaston a.j., gavrilo m. & ebert c. 2012. ice bridging as dispersal mechanism for arctic terrestrial vertebrates and the possible consequences of reduced sea ice cover. biodiversity 13, 182–190, http://dx.doi.org/10.1080/14888386.2012.7 19177. gebco 2019. general bathymetric chart of the oceans. accessed on the internet at https://www.gebco.net on 16 april 2019. geffen e., waidyaratne s., dalén l., angerbjörn a., vila c., hersteinsson p., fuglei e., white p.a., goltsman m. & wayne r.k. 2007. sea ice occurrence predicts genetic isolation in the arctic fox. molecular ecology 16, 4241–4255, http://dx.doi.org/10.1111/j.1365-294x.2007.03507.x. hamilton c., kovacs k., ims r.a., aars j. & lydersen c. 2017. an arctic predator–prey system in flux: climate change impacts on coastal space use by polar bears and ringed seals. journal of animal ecology 86, 1054–1064, http://dx.doi.org/10.1111/1365-2656.12685. hamilton c., lydersen c., ims r.a. & kovacs k. 2015. predictions replaced by facts: a keystone species’ behavioural responses to declining arctic sea-ice. biology letters 11, article no. 20150803, http://dx.doi.org/10.1098/rsbl. 2015.0803. hamilton w.d. & may r.m. 1977. dispersal instable habitats. nature 269, 578–581, http://dx.doi.org/10.1038/269578a0. hersteinsson p. & macdonald d.w. 1996. diet of arctic foxes (alopex lagopus) in iceland. journal of zoology 240, 457–474, http://dx.doi.org/10.1111/j.1469-7998.1996.tb05298.x. hijmans r.j. 2018. raster: geographic data analysis and modeling. r package version 2.8.4. accessed on the internet at https://cran.r-project.org/package=raster. ims r.a. & hjermann d.ø. 2001. condition dependent dispersal. in j. clobert et al. (eds.): dispersal. pp. 203–216. oxford: oxford university press. http://dx.doi.org/10.33265/polar.v38.3512� http://dx.doi.org/10.1038/srep40850� http://dx.doi.org/10.1038/srep40850� http://dx.doi.org/10.1046/j.0021-8790.2001.00581.x� http://dx.doi.org/10.1111/j.1365-294x.2007.03381.x� http://dx.doi.org/10.1111/j.1365-294x.2007.03381.x� http://dx.doi.org/10.1139/z68-161� http://dx.doi.org/10.2307/1380754� http://dx.doi.org/10.1007/s10021-014-9834-9� http://dx.doi.org/10.1111/j.0021-8790.2004.00885.x� http://dx.doi.org/10.1111/j.0021-8790.2004.00885.x� http://dx.doi.org/10.3184/003685008x327468� http://dx.doi.org/10.3184/003685008x327468� http://dx.doi.org/10.22621/cfn.v117i3.746� http://dx.doi.org/10.1080/14888386.2012.719177� http://dx.doi.org/10.1080/14888386.2012.719177� https://www.gebco.net� http://dx.doi.org/10.1111/j.1365-294x.2007.03507.x� http://dx.doi.org/10.1111/1365-2656.12685� http://dx.doi.org/10.1098/rsbl.2015.0803� http://dx.doi.org/10.1098/rsbl.2015.0803� http://dx.doi.org/10.1038/269578a0� http://dx.doi.org/10.1111/j.1469-7998.1996.tb05298.x� https://cran.r-project.org/package=raster� citation: polar research 2019, 38, 3512, http://dx.doi.org/10.33265/polar.v38.3512 7 (page number not for citation purpose) e. fuglei & a. tarroux arctic fox dispersal from svalbard to canada jonsen i. 2016. joint estimation over multiple individuals improves behavioural state inference from animal movement data. scientific reports 6, article no. 20625, http://dx. doi.org/10.1038/srep20625. jonsen i.d., mills flemming j. & myers r.a. 2005. robust state-space modeling of animal movement data. ecology 86, 2874–2880, http://dx.doi.org/10.1890/04-1852 lai s., bêty j. & berteaux d. 2015. spatio-temporal hotspots of satellite-tracked arctic foxes reveal a large detection range in a mammalian predator. movement ecology 3, article no. 37, http://dx.doi.org/10.1186/s40462-015-0065-2. lai s., bêty j. & berteaux d. 2017. movement tactics of a mobile predator in a meta-ecosystem with fluctuation resources: the arctic fox in the high arctic. oikos 126, 937–947, http://dx.doi.org/10.1111/oik.03948. laidre k.l. & heide-jørgensen m.p. 2011. life in the lead: extreme densities of narwhals monodon monoceros in the  offshore pack ice. marine ecology progress series 423, 269–278, http://dx.doi.org/10.3354/meps08941. lehner n.s. 2012. arctic fox winter movement and diet in relation to industrial development on alaska’s north slope. master of science thesis, faculty of the university of alaska fairbanks, fairbanks, ak. lydersen c. & gjertz i. 1986. studies of the ringed seal (phoca hispida schreber 1775) in its breeding habitat in kongsfjorden, svalbard. polar research 4, 57–63, http://dx.doi. org/10.3402/polar.v4i1.6920. nansen f. 1897. farthest north. london: gibson square books. norén k., carmichael l., fuglei e., eide n.e., hersteinsson p. & angerbjörn a. 2011. pulses of movement across the sea ice: population connectivity and temporal genetic structure in the arctic fox. oecologia 166, 973–984, http://dx. doi.org/10.1007/s00442-011-1939-7. norén k., hersteinsson p., samelius g., eide n.e., fuglei e., elmhagen b., dalén l., meijer t. & angerbjörn a. 2012. from monogamy to complexity: arctic fox social organization in contrasting ecosystems. canadian journal zoology 90, 1102–1116, http://dx.doi.org/10.1139/z2012-077. nybakk k., kjørstad m., overskaug k., kvam t. & linnell j.d.c., andersen r., berntsen f. 1996. experiences with live-capture and radio collaring of lynx (lynx lynx) in norway. fauna norvegica series a 17, 17–26. pamperin n.j., follmann e.h. & petersen b. 2008. sea-ice use by arctic foxes in northern alaska. polar biology 31, 1421–1426, http://dx.doi.org/10.1007/s00300-008-0481-5. prestrud p. 1992. food habits and observations of the hunting behaviour of arctic foxes, alopex lagopus, in svalbard. canadian field-naturalist 106, 225–236. pullainen e. 1965. on the distribution and migrations of the arctic fox (alopex lagopus l.) in finland. aquilo serie zoologica 2, 25–26. r development core team 2018. r: a language and environment for statistical computing. vienna: r foundation for statistical computing. rioux m.-j., lai s., casajus n., bêty j. & berteaux d. 2017. winter home range fidelity and extraterritorial movements of arctic fox pairs in the canadian high arctic. polar research 36 suppl. 1, article no. 11, http://dx.doi.org/10.10 80/17518369.2017.1316930. roth j.d. 2002. temporal variability in arctic fox diet as reflected in stable-carbon isotopes; the importance of sea ice. oecologia 133, 70–77, http://dx.doi.org/10.1007/ s00442-002-1004-7. smith t.g. 1980. polar bear predation of ringed and bearded seals in the land-fast sea ice habitat. canadian journal of zoology 58, 2201–2209, http://dx.doi.org/10.1139/z80-302 spreen g., kaleschke l. & heygster g. 2008. sea ice remote  sensing using amsr-e 89-ghz channels. journal of geophysical research—oceans 113, c02s03, http://dx.doi. org/10.1029/2005jc003384. tarroux a., berteaux d. & bêty j. 2010. northern nomads: ability for extensive movements in adult arctic foxes. polar biology 33, 1021–1026, http://dx.doi.org/10.1007/ s00300-010-0780-5. vacquie-garcia j., lydersen c., biuw m., haug t., fedak m.a. & kovacs k. 2017. hooded seal cystophora cristata foraging areas in the northeast atlantic ocean—investigated using three complementary methods. plos one 12, e0187889, http://doi.org/10.1371/journal.pone.0187889. vacquie-garcia j., lydersen c., ims r.a. & kovacs k. 2018. habitats and movement patterns of white whales delphinapterus leucas in svalbard, norway in a changing climate. movement ecology 6, article no. 21, http://dx.doi. org/10.1186/s40462-018-0139-z. vacquie-garcia j., lydersen c., marques t.a., aars j., ahonen h., skern-mauritzen m., oien n. & kovacs k. 2017. late summer distribution and abundance of ice-associated whales in the norwegian high arctic. endangered species research 32, 59–70, http://dx.doi.org/10.3354/esr00791. volodin a.a., kalashnikova m.v., klinkova e.s., goltsman a.m., goltsman m.e. & kruchenkova e.p. 2013. structure of arctic fox (alopex lagopus beringensis) colonies in the northern extremity of bering island. biology bulletin 40, 614–625, http://dx.doi.org/10.1134/s106235901307008x. weeks w. 2010. on sea ice. fairbanks: university of alaska press. wiig o., derocher a.e. & belikov s.e. 1999. ringed seal (phoca hispida) breeding in the drifting pack ice of the barents sea. marine mammal science 15, 595–598, http://dx. doi.org/10.1111/j.1748-7692.1999.tb00828.x. wrigley r.e. & hatch d.r.m. 1976. arctic fox migrations in manitoba. arctic 29, 147–157, http://dx.doi.org/10.14430/ arctic2798 http://dx.doi.org/10.33265/polar.v38.3512� http://dx.doi.org/10.1038/srep20625� http://dx.doi.org/10.1038/srep20625� http://dx.doi.org/10.1890/04-1852� http://dx.doi.org/10.1186/s40462-015-0065-2� http://dx.doi.org/10.1111/oik.03948� http://dx.doi.org/10.3354/meps08941� http://dx.doi.org/10.3402/polar.v4i1.6920� http://dx.doi.org/10.3402/polar.v4i1.6920� http://dx.doi.org/10.1007/s00442-011-1939-7� http://dx.doi.org/10.1007/s00442-011-1939-7� http://dx.doi.org/10.1139/z2012-077� http://dx.doi.org/10.1007/s00300-008-0481-5� http://dx.doi.org/10.1080/17518369.2017.1316930� http://dx.doi.org/10.1080/17518369.2017.1316930� http://dx.doi.org/10.1007/s00442-002-1004-7� http://dx.doi.org/10.1007/s00442-002-1004-7� http://dx.doi.org/10.1139/z80-302� http://dx.doi.org/10.1029/2005jc003384� http://dx.doi.org/10.1029/2005jc003384� http://dx.doi.org/10.1007/s00300-010-0780-5� http://dx.doi.org/10.1007/s00300-010-0780-5� http://doi.org/10.1371/journal.pone.0187889� http://dx.doi.org/10.1186/s40462-018-0139-z� http://dx.doi.org/10.1186/s40462-018-0139-z� http://dx.doi.org/10.3354/esr00791� http://dx.doi.org/10.1134/s106235901307008x� http://dx.doi.org/10.1111/j.1748-7692.1999.tb00828.x� http://dx.doi.org/10.1111/j.1748-7692.1999.tb00828.x� http://dx.doi.org/10.14430/arctic2798� http://dx.doi.org/10.14430/arctic2798� distribution and contamination assessment of heavy metals in soils and sediments from the fildes peninsula and ardley island in king george island, antarctica research article distribution and contamination assessment of heavy metals in soils and sediments from the fildes peninsula and ardley island in king george island, antarctica jing lin1,2, a.b.m. sadique rayhan2,3, yun wang4, zhai wu4, yan lin4, hongwei ke4, tianyao li4, kai chen2,3,4 & minggang cai2,3,4 1laboratory of marine isotopic technology and environmental risk assessment, third institute of oceanography, ministry of natural resources, xiamen, china 2fujian provincial key laboratory for coastal ecology and environmental studies, xiamen university, xiamen, china 3coastal and ocean management institute, xiamen university, xiamen, china 4college of ocean and earth science, xiamen university, xiamen, china abstract concentrations of heavy metals (cu, pb, zn, cd and cr) in surface soils and sediments collected in 2008 from 37 sampling sites in the fildes peninsula and ardley island were detected by atomic absorption spectrometry. the total contents of cu, pb, zn, cd and cr ranged, respectively, from 61.36 to 562.2 mg/kg, 0.52 to 1.95 mg/kg, 54.61 to 577.9 mg/kg, 0.04 to 3.76 mg/kg and 6.83 to 25.9 mg/kg in soils and from 58.55 to 498.3 mg/kg, 0.60 to 2.51 mg/kg, 56.22 to 345.9 mg/kg, 0.07 to 5.77 mg/kg and 7.76 to 39.5 mg/kg in sediments. the geo-accumulation index and the pollution load index were calculated to evaluate the environmental effects of heavy metal pollutants, cu, zn and cd, in the study area. soils and sediments from ardley island were found to be moderately polluted with the studied metals. pearson’s correlation analysis and principal component analysis were applied to assess the distribution pattern and potential source of heavy metals. the results suggest that cu, zn and cd in the study area originated from both the lithogenic sources and penguin guano, while pb and cr were probably derived from lithogenic sources. keywords trace element content; pollution assessment; penguin guano; multivariate statistical analysis; bio-transport of metals abbreviations aspa: antarctic specially protected area pli: pollution load index citation: polar research 2021, 40, 5270, http://dx.doi.org/10.33265/polar.v40.5270 copyright: polar research 2021. © 2021 j. lin et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 27 december 2021 competing interests and funding: the authors report no conflict of interest. this research work was supported by the national natural science foundation of china (grant nos. 41776088, 41976216), the national social science fund of china (grant no. 17vhq012), the fujian provincial natural science foundation of china (grant no. 2020j0141), marine science base scientific research training and scientific research ability enhancement project of xiamen university (grant no. j1210050) and xiamen university training program of innovation and entrepreneurship for undergraduates (grant nos. 2016x0619, 2016x0624, 2016x0629 and 103842017050). correspondence to: kai chen, 4221 xiangan south road, xiamen 361102, china. e-mail: kchen@xmu.edu.cn introduction the persistence, potential toxicity and bioaccumulation of heavy metals make them the most important contaminants in the environment (kaushik et al. 2009; yang et al. 2009). heavy metals can be adsorbed to the particulate matter in aquatic systems and will finally accumulate in sediments (wang et al. 2015; chen et al. 2018). however, the remobilization of heavy metals from surface sediments can cause contamination of the surrounding waters (yuan et al. 2004). sediments, therefore, play an important role as both sinks and potential secondary sources of heavy metals in aquatic ecosystems, and it is particularly important to explore the heavy metal contents in the surface sediments (zhang et al. 2016). considered as the last great wilderness, antarctica is the most isolated and remote continent on this planet. however, this does not protect antarctica from the deleterious impacts of pollution. contaminants from lower latitudes can reach the polar regions through atmospheric transport, current transport and even animal activities (majer et al. 2014; chu et al. 2019). increasing human activities in antarctica have caused several environmental pollution problems after the international geophysical year (1957–58), mainly near scientific stations (santos et al. 2005). king george island, the largest island in the south shetlands islands, has a high density of scientific stations, especially on the fildes peninsula, where six scientific stations have been established between 1968 and 1994 (amaro et al. 2015; bueno et al. 2018). in addition, the recent increase in the number of tourists to antarctica has caused widespread environmental concerns (kariminia et al. 2013). a number of studies have investigated heavy metal pollution in several environmental matrices in antarctica (e.g., wolff et al. 1999; sheppard et al. 2000; planchon et al. 2002; webster et al. 2003; santos et al. 2005; santos et al. 2006; chaparro et al. 2007; huang et al. 2014; trevizani et al. 2016). heavy metal concentrations in soils and lake sediments have been reported from the fildes peninsula and ardley island, a small island close off king george island (lu et al. 2012; amaro et al. 2015; bueno et al. 2018). these studies particularly focused on heavy metals near the scientific stations. surveys carried out in different years will improve our understanding of the cumulative environmental and anthropogenic changes occurring there. this study reported here aimed to determine and evaluate the levels of cu, pb, zn, cd and cr in samples of soils and coastal sediments collected in 2008 from the fildes peninsula and ardley island, and to consider their possible sources. nearly all of the areas that are affected by bird and human activities on the fildes peninsula and ardley island were sampled in this study. materials and methods study sites the fildes peninsula, in south-western king george island, is the second-largest ice-free coastal area (29 km2) during summer in the south shetland islands of antarctica. the climate here is cold, moist and maritime, with a mean annual air temperature of –2.2°c and about 630 mm in annual precipitation (michel et al. 2014). the soil from the fildes peninsula consists mostly of weathered volcanic rocks, especially andesitic basalts (li et al. 1992). aspa no. 125 was designated to protect two geologically important sites on the peninsula (peter et al. 2008). ardley island (62°12’0”s, 58°54’0”w) is 2 km in length and 1.5 km in width, and is connected to the fildes peninsula by a 400-m long isthmus, exposed during low tides (michel et al. 2014). ardley island hosts one of the largest breeding gentoo penguin (pygoscelis papua) colonies in the antarctic, alongside adélie (p. adeliae) and chinstrap (p. antarcticus) penguins (roberts et al. 2017). because of its diverse community of birds and terrestrial plants, ardley island has been designated aspa no. 150 for intensive research studies; however, it also includes a visitor zone (peter et al. 2008). sampling strategy a total of 37 sampling sites (fig. 1) were selected in the study areas during the 25th scientific antarctic expedition of china in december 2008. twenty-six soil samples were collected from the fildes peninsula (a-2–a-4, t-1–t-3, t-5–t-13 and s-2–s-9) and ardley island (a-5–a-7). eleven coastal sediment samples were collected from maxwell bay (a-1) and the great wall bay (s-1, s-10–s-14, a-8–a-11). fig. 1 map of sampling sites in the fildes peninsula and ardley island. the extent of the penguin breeding area is taken from roberts et al. (2017). soil samples (top 10 cm) were taken with a plastic spatula, while surface sediment samples (top 2 cm) were taken from the van veen grab sampler with a plastic scoop. the collected samples were stored in acid-washed polyethylene bags, and then transported to the laboratory and frozen at –18°c before further analysis. sample analysis after freeze-drying for at least 24 hours, sediment samples were divided into two sub-samples, one for the grain size study and the other for the heavy metal analysis. particle-size distribution was determined by a laser mastersizer 2000. other sub-samples were powdered and homogenized with an agate mortar to pass through a 180-mesh sieve (80 μm) for metal analysis. for each of the powdered samples, 0.1 g was digested with a mixture of hno3 and hclo4, using the method described by cai et al. (2011). samples were then analysed by flame atomic absorption spectrometry for zn and by graphite furnace atomic absorption spectrometry for cu, cd, pb and cr (solaar m6, thermo scientific co.). milli-q water was used throughout the study. all glassware, plasticware, pipette tips and polytetrafluoroethylene vessels were soaked in hno3 solution (1:3 v/v) for at least 48 hours and rinsed with milli-q water before use. quality assurance and quality control were assessed using method blanks, duplicate samples and standard reference material (gbw07314) in triplicate. the results for the selected metals are shown in table 1. the recoveries obtained in the standard reference material ranged from 92 to 116%. the relative standard deviation (%), indicating the precision of duplicate samples, ranged from 1.13 to 5.28%.   table 1 measured and certified values of metal contents in standard reference material. element limit of detection (μg/l) measured value (μg/g) assigned value (μg/g) rsda (%) cu 0.10 36.15 ± 1.15 32 ± 2 3.17 pb 0.19 59.06 ± 2.10 61 ± 2 3.56 zn 1.58 116.12 ± 1.31 100 ± 8 1.13 cd 0.02 0.23 ± 0.01 0.25 ± 0.02 2.47 cr 0.62 67.70 ± 3.57 67 ± 3 5.28 arelative standard deviation. assessment of sediment contamination geo-accumulation index (igeo). the widely applied geo-accumulation index (igeo) is used to evaluate the heavy metal contamination status of sediments in a water body (müller 1969). it is calculated by the following equation: where cn is the measured metal concentration (n), bn is the concentration of metal in the geochemical background (n), and 1.5 is the background matrix correlation factor of the lithogenic and anthropogenic influences (hakanson 1980; sheppard et al. 2000). the geo-accumulation index can be divided into seven classes from class 0 to class 6: igeo values of ≤ 0 suggest unpolluted, 0 < igeo ≤ 1 indicates unpolluted to moderately polluted, 1 < igeo ≤ 2 suggests moderately polluted, igeo values of 2–3 represent moderately to heavily polluted, 3 < igeo ≤ 4 suggests heavily polluted, 4 < igeo ≤ 5 demonstrates heavily to extremely polluted and values exceeding 5 indicate severely polluted (müller 1979). pli. pli provides a simple and reliable way to assess the polymetallic contamination of sediment (tomlinson et al. 1980), which is calculated by the following equation: where cf is the contamination factor and n is the number of analysed metals. cf is the ratio obtained by dividing the content of each metal in sediment by the background value that was developed by hakanson (1980). according to tomlinson et al. (1980), pli > 1 indicates the presence of polymetallic pollution, while there is no metal pollution when pli < 1. in this study, the background values of heavy metals on the fildes peninsula are adopted from lu et al. (2012), which was determined by the method of relative cumulative frequency. the background concentrations of cu, pb, zn, cd and cr were 89.45, 5.44, 51.41, 0.09 and 22.56 mg/kg, respectively. multivariate statistical analyses we applied pearson’s correlation analysis to determine the relationships among all the selected heavy metals and particle-size distribution. a two-tailed p value of < 0.05 was considered to be statistically significant. principal component analysis was used to discriminate the potential sources of heavy metals based on the similarities of their chemical properties. principal component analysis was applied with kaiser-meyer-olkin and bartlett’s sphericity tests and was performed on the correlation matrix of normalized variables. to extract significant principal components and to further reduce the contribution of variables with minor significance, principal components were subjected to varimax rotation. all statistical analyses were performed with ibm® spss® 25.0 software for windows and origin 2021. results and discussion particle-size analysis coarse sand (>250 μm), fine sand (63–250 μm), silt (4–63 μm) and clay (<4 μm) fractions in soils and sediments of the fildes peninsula and ardley island ranged from 0 to 44.9%, 14.5 to 58.3%, 14.5 to 72.2% and 0.39 to 18.1%, respectively (table 2). particle-size distributions varied greatly among the studied sites, with silt and fine sand being the predominant fractions in soils and sediments (fig. 2). the clay fractions of surface soils and sediments were relatively low in the study area, which is consistent with a study by michel et al. (2014) that reported low clay content in soils from the fildes peninsula and ardley island.   table 2 particle-size fraction (%) and heavy metal concentrations (mg/kg) in this study. site clay silt fine sand coarse sand cu pb zn cd cr fildes peninsula soil samples s-2 2.49 26.8 58.3 12.3 157.4 1.11 126.8 0.13 13.4 s-3 4.02 30.0 45.7 20.2 203.7 1.66 134.0 0.21 15.6 s-4 4.33 29.7 28.8 37.2 197.0 1.25 140.3 0.14 14.9 s-5 5.29 36.5 41.4 16.8 192.9 1.32 123.7 0.18 10.2 s-6 5.33 40.3 39.8 14.6 168.8 1.03 148.1 0.28 17.1 s-7 3.18 24.7 46.7 25.3 160.7 1.39 135.4 0.12 16.1 s-8 3.53 42.8 35.4 18.2 192.9 1.95 155.6 0.24 16.6 s-9 4.56 47.3 40.2 7.99 96.06 0.52 70.06 0.08 6.83 t-1 7.96 51.8 33.2 7.05 208.1 1.24 280.2 0.08 10.4 t-2 12.6 64.0 22.4 0.90 312.2 1.43 133.6 0.08 11.7 t-3 8.99 58.9 28.6 3.55 104.4 0.89 73.41 0.06 12.1 t-5 12.4 60.9 24.8 1.88 166.6 0.85 108.3 0.05 10.2 t-6 18.1 66.1 15.6 0.20 121.9 0.89 94.45 0.07 10.1 t-7 12.1 59.4 26.1 2.46 145.5 1.33 82.49 0.06 10.2 t-8 13.2 69.7 17.2 0.00 159.9 0.90 90.13 0.06 10.8 t-9 8.36 52.4 35.2 3.99 151.9 0.86 88.34 0.06 14.8 t-10 12.1 68.8 18.1 1.02 169.0 0.98 101.1 0.04 22.9 t-11 2.75 34.2 43.8 19.2 132.0 1.36 99.78 0.13 9.98 t-12 9.55 56.6 29.3 4.54 166.0 0.53 80.65 0.04 25.9 t-13 13.4 72.2 14.5 0.00 137.6 0.99 102.1 0.13 11.3 a-2 10.6 57.1 27.5 4.84 61.36 0.86 54.61 0.06 18.2 a-3 11.7 53.8 30.1 4.43 78.53 1.10 58.52 0.05 12.5 a-4 11.0 71.1 16.8 1.14 98.39 1.31 72.54 0.06 9.65 ardley island soil samples a-5 12.7 65.5 17.3 4.53 256.9 1.61 77.68 0.14 23.9 a-6 1.20 23.4 44.3 31.1 562.2 nda 577.9 3.76 7.85 a-7 9.32 55.3 31.0 4.45 209.8 0.97 127.2 0.45 18.8 ardley island sediment samples a-9 0.76 17.6 37.0 44.7 68.41 0.95 74.11 0.25 8.59 a-11 2.87 36.3 44.1 16.8 69.64 2.51 109.6 0.16 11.6 a-1 4.46 47.4 42.2 5.88 187.4 1.65 72.87 0.07 39.5 a-8 16.4 66.9 15.7 0.95 160.4 2.11 114.7 0.09 18.0 a-10 4.52 39.1 43.9 12.6 58.55 0.60 62.23 0.33 12.7 s-1 0.71 25.1 37.4 36.9 131.1 1.29 119.7 0.67 11.0 s-10 1.76 27.0 45.6 25.6 498.3 1.89 345.9 5.77 21.5 s-11 0.49 14.5 40.1 44.9 153.8 0.70 243.2 2.36 10.1 s-12 0.39 19.7 50.7 29.3 270.3 1.75 56.22 0.25 7.76 s-13 0.96 18.6 44.6 35.9 116.9 1.51 137.4 0.91 11.9 s-14 1.77 29.1 43.1 25.9 80.81 1.25 96.58 0.54 10.0 ano data. fig. 2 the particle-size distributions of sampling sites in the fildes peninsula and ardley island. concentrations of heavy metals the concentrations of heavy metals from different areas of the fildes peninsula and ardley island are shown in table 2. the concentrations of cu, pb, zn, cd and cr in soils and sediments were in the range of 58.55–562.2 mg/kg (average 173.2 ± 104.3 mg/kg), 0.52–2.51 mg/kg (average 1.24 ± 0.45 mg/kg), 54.61–577.9 mg/kg (average 128.9 ± 96.9 mg/kg), 0.04–5.77 mg/kg (average 0.49 ± 1.14 mg/kg) and 6.83–39.5 mg/kg (average 14.2 ± 6.3 mg/kg), respectively. compared with the earth’s crust values (wedepohl 1995), the concentrations of cu, zn and cd in the fildes peninsula and ardley island found in this study were significantly higher, except for cd in fildes peninsula soils (table 3). the concentrations of cu, zn and cd in soils from the fildes peninsula found in this study were lower than those in human-affected soils (abakumov et al. 2017). compared to pristine areas in the antarctic (ahn et al. 1996; santos et al. 2006; chaparro et al. 2007; lu et al. 2012; amaro et al. 2015; abakumov et al. 2017), the concentrations of cu, zn and cd in soils and sediments from the fildes peninsula and ardley island were higher, with the exception of cd levels in fildes peninsula soils. in other words, our sampling sites on the fildes peninsula were affected by zn and cu (ribeiro et al. 2011; trevizani et al. 2016), and the ardley island sediments were affected by zn, cu and cd.   table 3 comparison of heavy metal concentrations in sediments and soils from different areas in the antarctic (mean ± sd, mg/kg). location cu pb zn cd cr soil fildes peninsulaa 155.8 ± 52.7 1.12 ± 0.34 111.1 ± 47.0 0.10 ± 0.07 13.5 ± 4.5 ardley islanda 343.0 ± 191.3 1.29 ± 0.45 260.9 ± 275.6 1.45 ± 2.01 16.8 ± 8.2 ardley islandb 30 ± 6 23 ± 3 104 ± 7 0.28 ± 0.04 fildes peninsulac 122.30 ± 32.12 15.87 ± 13.49 58.69 ± 9.36 0.17 ± 0.08 31.95 ± 13.82 fildes peninsula: human-affected soilsd 186.33 ± 36.00 203.16 ± 49.91 134.67 ± 26.50 0.44 ± 0.22 fildes peninsula: pristine soilsd 65.00 ± 13.00 5.96 ± 1.50 42.10 ± 8.48 0.25 ± 0.13 marambio station, seymour islande 6.1 10.2 36 <0.8 22 sediment maxwell bay and great wall baya 163.2 ± 127.7 1.47 ± 0.59 130.2 ± 88.2 1.04 ± 1.70 14.8 ± 9.1 collins harborf 77 8.7 69 0.22 7.6 ferraz stationg 67 5.5 52 35 rocks global averageh 25 14.8 65 0.10 126 athis study. bamaro et al. (2015). clu et al. (2012). dabakumov et al. (2017). echaparro et al. (2007). fahn et al. (1996). gsantos et al. (2006). hwedepohl (1995). the relatively high concentrations of zn and cu could be associated with a mineralogical origin where basalt–andesite rocks predominate (bueno et al. 2018). another reasonable explanation is that penguins transport heavy metals in antarctic coastal areas (santamans et al. 2017). over 10 000 penguins live on ardley island during the breeding season, producing about 139 tonnes of faeces rich in heavy metals (wang et al. 2007; roberts et al. 2017; fig. 1). celis et al. (2015) found that gentoo penguins transfer bio-accumulated metals into terrestrial ecosystems via excreta. in this study, higher concentrations of zn, cu and cd were found at site a-6, located in the penguin nesting area, whereas lower levels were observed at sites a-5 and a-7, which were beyond the penguin nesting area (fig. 4). this suggests that penguins transfer a large quantity of heavy elements from the ocean to the island. there were no significant differences in cr and pb values among the sampling sites on the fildes peninsula and ardley island (figs. 3, 4). as the distribution patterns of cr and pb were uniform and much lower than those in pristine areas (lu et al. 2012; abakumov et al. 2017), they are considered not to be affected by human influences and could be related to lithogenic inputs in this study area (azhari et al. 2016). fig. 3 the distribution of heavy metals in soils on the fildes peninsula. fig. 4 the distribution of metals in soils and sediments on ardley island. pollution assessment geo-accumulation index. igeo values of heavy metals in soils and sediments from the fildes peninsula and ardley island are presented in table 4. the igeo values of cu and zn in soils from the fildes peninsula were lower than 1.0, indicating that this area was “unpolluted to moderately polluted” by these two metals. the soils from ardley island were found to be “moderately polluted,” with cu and zn (1 < igeo ≤ 2), and “moderately to heavily polluted,” with cd (2.20 ± 2.41). igeo values of metals in sediments suggested that the study area was “unpolluted to moderately polluted” by zn and “moderately polluted” by cd. in contrast, the average geo-accumulation indexes of pb and cr were both less than zero, indicating an unpolluted level.   table 4 geo-accumulation indexes and pli in soils and sediments from the fildes peninsula and ardley island. sample type (number of samples) igeo pli cu pb zn cd cr soil, fildes peninsula (n = 23) mean 0.13 −2.93 0.43 −0.61 −1.39 0.85 sda 0.51 0.46 0.53 0.83 0.44 0.23 soil, ardley island (n = 3) mean 1.22 −2.71 1.21 2.20 −1.15 1.25 sda 0.75 0.52 1.51 2.41 0.85 0.13 sediment (n = 11) mean −0.02 −2.59 0.53 1.67 −1.37 1.32 sda 0.94 0.65 0.81 1.93 0.68 0.87 astandard deviation. pli. soils from the fildes peninsula were calculated with a mean pli of 0.85, which means no pollution (table 4). in contrast, the mean plis of soils and coastal sediments from ardley island were both more than 1, suggesting that the area was moderately polluted by metals. multivariate statistical analyses pearson’s correlation analysis. heavy metals in soils showed no significant correlation with the particle-size distribution (table 5). this was unexpected as heavy metals have generally been found to be associated with the fine-grain fraction in sediments (chen et al. 2016). the same result was also observed near artigas base and ferraz station (santos et al. 2005; bueno et al. 2018), also located on king george island, indicating that heavy metal concentrations in soils and sediments cannot be interpreted simply by a change in grain size.   table 5 the results of pearson’s correlation analysis between heavy metals and particle size. boldface indicates statistical significance at the < 0.05 level (two-tailed); italics indicate significance at the < 0.01 level (two-tailed). metal cu pb zn cd cr clay silt fine sand coarse sand cu 1 pb 0.361 1 zn 0.798 0.235 1 cd 0.730 0.181 0.784 1 cr 0.132 0.171 −0.114 0.011 1 clay −0.188 −0.192 −0.337 −0.395 0.109 1 silt −0.201 −0.188 −0.367 −0.423 0.191 0.934 1 fine sand 0.170 0.181 0.269 0.310 −0.060 −0.884 −0.860 1 coarse sand 0.185 0.161 0.374 0.434 −0.240 −0.840 −0.921 0.603 1 significant positive correlations were observed among cu, zn and cd, while pb and cr were not significantly correlated with any other metals (table 5). the results suggested a similar biogeochemical behaviour for cu, zn and cd. santamans et al. (2017) demonstrated that greater penguin activity was associated with higher levels of certain pollutants in soils, especially cd, cu, as, zn and se. principal component analysis. the kaiser–meyer–olkin value was 0.695, and the significance of bartlett’s sphericity test was less than 0.01, which indicated that principal component analysis for this study was significant. all sites could be grouped into two principal components, pc1 and pc2, which account for 94.77% of the total variance (fig. 5). pc1 and pc2 generated 78.43% and 16.34% of the variance, respectively. a positive (negative) score indicates that the influence of variables increases (decreases) along a principal component axis, and a score near 0 indicates that the influence of variables is poorly related to the principal component axis (wang et al. 2021). we observed obtuse angles (i.e., negative correlation) between the cu and zn; however, cu was significantly correlated with zn based on pearson’s correlation test (r = 0.798, p < 0.05; fig. 5, table 5). this may be an artefact of the principal component analysis used in this study, which was based on a covariance matrix, because the units of heavy metal concentration and particle size are different (singh et al. 2005). fig. 5 principal component analysis biplot of heavy metal concentrations (mg/kg) and particle-size fraction (%) at the sampling sites on the fildes peninsula and ardley island. the distributions of other variables—pb, cd, cr, clay, silt, fine sand and coarse sand—were hardly affected by either pc1 or pc2, as they are close to the origin of coordinates. the locations (e.g., t1 and s11) on the positive side end of the zn axis had concentrations of zn higher than that of cu in soils or sediments. in contrast, the locations (e.g., a5, s12 and t2) on the positive side end of the cu axis had concentrations of cu higher than that of zn in soils or sediments. considering their geographical proximity, especially t1 and t2, and s11 and s12, it seems that this difference did not originate from external factors, such as air deposition or penguin activities. we speculate that local human activities or geological features are possible sources leading to the differences found (boutron & wolff 1989; lu et al. 2012); however, further study is needed to confirm this. conclusion the results of this study provide an overview of selected heavy metals in samples of surface soils and coastal sediments collected in 2008 from the fildes peninsula and ardley island, antarctica. calculations of igeo for soils and sediments from the fildes peninsula and ardley island showed an accumulation of cu, zn and cd. pli results demonstrated that soils and sediments on ardley island were moderately polluted with these metals. these areas can be considered unpolluted by pb and cr. the study strongly suggests that cu, zn and cd in the study area originate from the lithogenic sources and penguin guano, whereas pb and cr probably derive from lithogenic sources alone. seabird activities have increased the amount of cu, zn and pb on ardley island. it is necessary to monitor the bio-transport of trace metals and their impact on the food chain of antarctica. when compared with other published heavy metal concentrations on the fildes peninsula and ardley island since our sampling, cu, zn and cd levels in soils became higher after 2008, especially near human-affected locations, such as research stations. in the pristine soils of the area, however, cu and zn remained constant. acknowledgements the authors thank the crews of chinare-25 and the group members for their help in sampling and analysis. they also thank the anonymous reviewers for their patience and kind and valuable comments. references abakumov e., lupachev a. & andreev m. 2017. trace element content in soils of the king george and elephant islands, maritime antarctica. chemistry and ecology 33, 856–868, doi: 10.1080/02757540.2017.1384821. ahn i.-y., lee s.h., kim k.t., shim j.h. & kim d.-y. 1996. baseline heavy metal concentrations in the antarctic clam, laternula elliptica in maxwell bay, king george island, antarctica. marine pollution bulletin 32, 592–598, doi: 10.1016/0025-326x(95)00247-k. amaro e., padeiro a., mão de ferro a., mota a.m., leppe m., verkulich s., hughes k.a., peter h.-u. & canário j. 2015. assessing trace element contamination in fildes peninsula (king george island) and ardley island, antarctic. marine pollution bulletin 97, 523–527, doi: 10.1016/j.marpolbul.2015.05.018. azhari a.e., rhoujjati a. & hachimi m.l.e. 2016. assessment of heavy metals and arsenic contamination in the sediments of the moulouya river and the hassan ii dam downstream of the abandoned mine zeïda (high moulouya, morocco). journal of african earth sciences 119, 279–288, doi: 10.1016/j.jafrearsci.2016.04.011. boutron c.f. &wolff e.w. 1989. heavy metal and sulphur emissions to the atmosphere from human activities in antarctica. atmospheric environment 23, 1669–1675, doi: 10.1016/0004-6981(89)90051-6. bueno c., kandratavicius n., venturini n., figueira r.c.l., pérez l., iglesias k. & brugnoli e. 2018. an evaluation of trace metal concentration in terrestrial and aquatic environments near artigas antarctic scientific base (king george island, maritime antarctica). water, air, & soil pollution 229, article no. 398, doi: 10.1007/s11270-018-4045-1. cai m.h., lin j., hong q.q., wang y. & cai m.g. 2011. content and distribution of trace metals in surface sediments from the northern bering sea, chukchi sea and adjacent arctic areas. marine pollution bulletin 63, 523–527, doi: 10.1016/j.marpolbul.2011.02.007. celis j., barra r., espejo w., gonzález-acuña d. & jara s. 2015. trace element concentrations in biotic matrices of gentoo penguins (pygoscelis papua) and coastal soils from different locations of the antarctic peninsula. water air and soil pollution 226, article no. 2266, doi: 10.1007/s11270-014-2266-5. chaparro m.a., nuñez h., lirio j.m., gogorza c.s. & sinito a.m. 2007. magnetic screening and heavy metal pollution studies in soils from marambio station, antarctica. antarctic science 19, 379–393, doi: 10.1017/s0954102007000454. chen f., lin j., qian b., wu z., huang p., chen k., li t. & cai m. 2018. geochemical assessment and spatial analysis of heavy metals in the surface sediments in the eastern beibu gulf: a reflection on the industrial development of the south china coast. international journal of environmental research and public health 15, article no. 496, doi: 10.3390/ijerph15030496. chen y., gao j., yuan y., ma j. & yu s. 2016. relationship between heavy metal contents and clay mineral properties in surface sediments: implications for metal pollution assessment. continental shelf research 124, 125–133, doi: 10.1016/j.csr.2016.06.002. chu z., yang z., wang y., sun l., yang w., yang l. & gao y. 2019. assessment of heavy metal contamination from penguins and anthropogenic activities on fildes peninsula and ardley island, antarctic. science of the total environment 646, 951–957, doi: 10.1016/j.scitotenv.2018.07.152. hakanson l. 1980. an ecological risk index for aquatic pollution control—a sedimentological approach. water research 14, 975–1001, doi: 10.1016/0043-1354(80)90143-8. huang t., sun l., wang y., chu z., qin x. & yang l. 2014. transport of nutrients and contaminants from ocean to island by emperor penguins from amanda bay, east antarctic. science of the total environment 468–469, 578–583, doi: 10.1016/j.scitotenv.2013.08.082. kariminia s., ahmad s.s., hashim r. & ismail z. 2013. environmental consequences of antarctic tourism from a global perspective. procedia—social and behavioral sciences 105, 781–791, doi: 10.1016/j.sbspro.2013.11.081. kaushik a., kansal a., santosh meena, kumari s. & kaushik c.p. 2009. heavy metal contamination of river yamuna, haryana, india: assessment by metal enrichment factor of the sediments. journal of hazardous materials 164, 265–270, doi: 10.1016/j.jhazmat.2008.08.031. li z., liu x. & shang r. 1992. the characteristics and mechanism of island-arc volcanism on the central and southern fildes peninsula, king george island, antarctica. acta geologica sinica 5, 39–57, doi: 10.1111/j.1755-6724.1992.mp5001003.x. lu z., cai m., wang j., yang h. & he j. 2012. baseline values for metals in soils on fildes peninsula, king george island, antarctica: the extent of anthropogenic pollution. environmental monitoring and assessment 184, 7013–7021, doi: 10.1007/s10661-011-2476-x. majer a.p., petti m.a.v., corbisier t.n., ribeiro a.p., theophilo c.y.s., ferreira p.a.d.l. & figueira r.c.l. 2014. bioaccumulation of potentially toxic trace elements in benthic organisms of admiralty bay (king george island, antarctica). marine pollution bulletin 79, 321–325, doi: 10.1016/j.marpolbul.2013.12.015. michel r.f.m., schaefer c.e.g.r., lópez-martínez j., simas f.n.b., haus n.w., serrano e. & bockheim j.g. 2014. soils and landforms from fildes peninsula and ardley island, maritime antarctica. geomorphology 225, 76–86, doi: 10.1016/j.geomorph.2014.03.041. müller g. 1969. index of geoaccumulation in sediments of the rhine river. geojournal 2, 108–118. müller g. 1979. schwermettalle in den sedimenten des rheins—veranderungen seit 1971. (heavy metals in the sediments of the rhine—changes since 1971.) umschau 79, 778–783. peter h.-u., buesser c., mustafa o. & pfeiffer s. 2008. risk assessment for the fildes peninsula and ardley island, and development of management plans for their designation as specially protected or specially managed areas. dessau, germany: german environmental agency. planchon f.a.m., boutron c.f., barbante c., cozzi g., gaspari v., wolff e.w., ferrari c.p. & cescon p. 2002. changes in heavy metals in antarctic snow from coats land since the mid-19th to the late-20th century. earth and planetary science letters 200, 207–222, doi: 10.1016/s0012-821x(02)00612-x. ribeiro a.p., figueira r.c.l., martins c.c., silva c.r.a., frança e.j., bícego m.c., mahiques m.m. & montone r.c. 2011. arsenic and trace metal contents in sediment profiles from the admiralty bay, king george island, antarctica. marine pollution bulletin 62, 192–196, doi: 10.1016/j.marpolbul.2010.10.014. roberts s.j., monien p., foster l.c., loftfield j., hocking e.p., schnetger b., pearson e.j., juggins s., fretwell p., ireland l., ochyra r., haworth a.r., allen c.s., moreton s.g., davies s.j., brumsack h.-j., bentley m.j. & hodgson d.a. 2017. past penguin colony responses to explosive volcanism on the antarctic peninsula. nature communication 8, article no. 14914, doi: 10.1038/ncomms14914. santamans a.c., boluda r., picazo a., gil c., ramos-miras j., tejedo p., pertierra l.r., benayas j. & camacho a. 2017. soil features in rookeries of antarctic penguins reveal sea to land biotransport of chemical pollutants. plos one 12, e0181901, doi: 10.1371/journal.pone.0181901. santos i.r., silva-filho e.v., schaefer c.e., albuquerque-filho m.r. & campos l.s. 2005. heavy metals contamination in coastal sediments and soils near the brazilian antarctic station, king george island. marine pollution bulletin 50, 185–194, doi: 10.1016/j.marpolbul.2004.10.009. santos i.r., silva-filho e.v., schaefer c.e., sella s.m., silva c., gomes v., passos m.j. & van ngan p. 2006. baseline mercury and zinc concentrations in terrestrial and coastal organisms of admiralty bay, antarctica. environmental pollution 140, 304–311, doi: 10.1016/j.envpol.2005.07.007. sheppard d.s., claridge g.g.c. & campbell i.b. 2000. metal contamination of soils at scott base, antarctica. applied geochemistry 15, 513–530, doi: 10.1016/s0883-2927(99)00055-4. singh k.p., malik a., sinha s., singh v.k. & murthy r.c. 2005. estimation of source of heavy metal contamination in sediments of gomti river (india) using principal component analysis. water, air, and soil pollution 166, 321–341, doi: 0.1007/s11270-005-5268-5. tomlinson d.l., wilson j.g., harris c.r. & jeffrey d.w. 1980. problems in the assessment of heavy-metal levels in estuaries and the formation of a pollution index. helgoländer meeresuntersuchungen 33, 566–575, doi: 10.1007/bf02414780. trevizani t.h., figueira r.c.l., ribeiro a.p., theophilo c.y.s., majer a.p., petti m.a.v., corbisier t.n. & montone r.c. 2016. bioaccumulation of heavy metals in marine organisms and sediments from admiralty bay, king george island, antarctica. marine pollution bulletin 106, 366–371, doi: 10.1016/j.marpolbul.2016.02.056. wang j., wang y., wang x. & sun j. 2007. penguins and vegetations on ardley island, antarctica: evolution in the past 2,400 years. polar biology 30, 1475–1481, doi: 10.1007/s00300-007-0308-9. wang x., liu k., zhu l., li c., song z. & li d. 2021. efficient transport of atmospheric microplastics onto the continent via the east asian summer monsoon. journal of hazardous materials 414, article no. 125477, doi: 10.1016/j.jhazmat.2021.125477. wang y., yang l., kong l., liu e., wang l. & zhu j. 2015. spatial distribution, ecological risk assessment and source identification for heavy metals in surface sediments from dongping lake, shandong, east china. catena 125, 200–205, doi: 10.1016/j.catena.2014.10.023. webster j., webster k., nelson p. & waterhouse e. 2003. the behaviour of residual contaminants at a former station site, antarctica. environmental pollution 123, 163–179, doi: 10.1016/s0269-7491(02)00403-7. wedepohl k.h. 1995. the composition of the continental crust. geochimica et cosmochimica acta 59, 1217–1232, doi: 10.1016/0016-7037(95)00038-2. wolff e.w., suttie e.d. & peel d.a. 1999. antarctic snow record of cadmium, copper, and zinc content during the twentieth century. atmospheric environment 33, 1535–1541, doi: 10.1016/s1352-2310(98)00276-3. yang z., wang y., shen z., niu j. & tang z. 2009. distribution and speciation of heavy metals in sediments from the mainstream, tributaries, and lakes of the yangtze river catchment of wuhan, china. journal of hazardous materials 166, 1186–1194, doi: 10.1016/j.jhazmat.2008.12.034. yuan c.-g., shi j.-b., he b., liu j.-f., liang l.-n. & jiang g.-b. 2004. speciation of heavy metals in marine sediments from the east china sea by icp-ms with sequential extraction. environment international 30, 769–783, doi: 10.1016/j.envint.2004.01.001. zhang z., li j., mamat z. & ye q. 2016. sources identification and pollution evaluation of heavy metals in the surface sediments of bortala river, northwest china. ecotoxicology and environmental safety 126, 94–101, doi: 10.1016/j.ecoenv.2015.12.025. a comparison of an operational wave–ice model product and drifting wave buoy observation in the central arctic ocean: investigating the effect of sea-ice forcing in thin ice cover research article a comparison of an operational wave–ice model product and drifting wave buoy observation in the central arctic ocean: investigating the effect of sea-ice forcing in thin ice cover takehiko nose1, jean rabault2, takuji waseda1, tsubasa kodaira1, yasushi fujiwara1,3, tomotaka katsuno1, naoya kanna4, kazutaka tateyama5, joey voermans6 & tatiana alekseeva7,8 1department of ocean technology, policy and environment, graduate school of frontier sciences, the university of tokyo, kashiwa, chiba, japan 2norwegian meteorological institute, it department, oslo, norway 3graduate school of maritime sciences, kobe university, kobe, japan 4atmosphere and ocean research institute, the university of tokyo, kashiwa, chiba, japan 5kitami institute of technology, kitami, hokkaido, japan 6university of melbourne, melbourne, australia 7arctic and antarctic research institute, saint petersburg, russia 8space research institute, moscow, russia abstract a prototype openmetbuoy (omb) was deployed alongside a commercial buoy in the central arctic ocean, north of the laptev sea, where there are historically no wave observations available. the inter-buoy comparison showed that the omb measured wave heights and periods accurately, so the buoy data were used to study the predictability of a wave–ice model. the first event we studied was when both buoys observed a sudden decrease in significant wave heights hm0, which was caused by the change of wind directions from along the ice edge to off-ice wind. the arctic ocean wave analysis and forecast wave–ice model product (arc mfc) underestimated the hm0 on the account of the fetch being constrained by the inaccurate model representation of an ice tongue. the second case was an on-ice wave event as new ice formed. in this instance, the arc mfc wave–ice model product largely underestimated the downwind buoy hm0. model sea-ice conditions were examined by comparing the arc mfc sea-ice forcing with the nextsim sea-ice model product, and our analysis revealed the arc mfc did not resolve thin ice thickness distribution for ice types like young and grey ice, typically less than 30 cm. the arc mfc model’s wave dissipation rate has a sea-ice thickness dependence and overestimated wave dissipation in thin ice cover; sea-ice forcing that can resolve the thin thickness distribution is needed to improve the predictability. this study provides an observational insight into better predictions of waves in marginal ice zones when new ice forms. keywords openmetbuoy; arc mfc wave–ice model; nextsim sea-ice model; wave–ice interaction; miz wave predictability; ice thickness abbreviations amsr2: advanced microwave scanning radiometer 2 arc mfc: arctic ocean wave analysis and forecast (produced by the copernicus marine arctic monitoring and forecast center) cmems: copernicus marine environment monitoring service gnss: global navigation satellite system gps: global positioning system ecmwf hres: high resolution forecast (produced by the european centre for medium-range weather forecasts) hycom: hybrid coordinate ocean model (sponsored by the national ocean partnership program) imu: inertial measurement unit miz: marginal ice zone nabos: nansen and amundsen basins observational system (part of the arctic observing network) nextsim: sea-ice forecast (produced by the nansen environmental and remote sensing center) omb: openmetbuoy osi saf: ocean and sea ice satellite application facility ostia: operational sea surface temperature and ice analysis (produced by the uk met office) sic: sea-ice concentration sit: sea-ice thickness topaz4: towards an operational prediction system for the north atlantic european coastal zones (version 4) data assimilation system   citation: polar research 2023, 42, 8874, http://dx.doi.org/10.33265/polar.v42.8874 copyright: polar research 2023. © 2023 t. nose et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 02 august 2023 competing interests and funding: the authors report no conflict of interest. drs n. kanna and k. tateyama were supported by the arcs ii japan-russia-canada international exchange program to participate in the 2021 nabos expedition. this work was a part of the arctic challenge for sustainability ii (arcs ii) project (program grant no. jpmxd1420318865). a part of this study was also conducted under jsps kakenhi grant nos. jp 19h00801, 19h05512, 21k14357 and 22h00241. correspondence: takehiko nose, department of ocean technology, policy and environment, graduate school of frontier sciences, university of tokyo, 5–1–5 kashiwanoha, kashiwa, chiba, japan. e-mail tak.nose@edu.k.u-tokyo.ac.jp to access the supplementary material, please visit the article landing page   introduction wave–ice interaction research is attracting renewed attention because of declining arctic ocean sea-ice cover and a conjecture that waves in ice have an influence on the climate system (squire 2018, 2020). despite recent advancement in model parameterization since one of the most intensive waves-in-ice data collection campaigns of thomson et al. (2018), incorporating the effects of waves in sea-ice models and vice versa remains a challenging problem. in mizs, where the sea-ice field is heterogeneous and waves are most dynamic, the problem becomes even more challenging as accurate sea-ice condition is difficult to obtain. uncertainty arising from sic estimates (from passive microwave radiometers) used as sea-ice forcing for wave–ice models can even overwhelm the uncertainty of wave–ice interaction parameterizations (nose et al. 2020). in light of these challenges, it can be argued that more observations are needed to better understand wave–ice interaction physics and improve the predictability of ocean waves in mizs. utilizing the recent advances of inexpensive electronics and their open-source philosophy, rabault et al. (2022) developed and introduced a low-cost, easy to build wave–ice buoy called omb. the omb applies a 6 degrees of freedom imu to measure vertical ocean surface motion. the vertical surface oscillation can then be used to obtain power spectral density, from which integrated wave statistics like the wave height and periods can be calculated. in september 2021, our research team joined the nabos campaign (nabos no date) on board the rv akademik tryoshnikov, and we deployed a prototype of the omb alongside a commercial wave buoy in the central arctic ocean, where there are historically no wave observations available. in this study, we evaluated our prototype omb with a commercial wave buoy; we then used the buoy data set to study the wave–ice model predictability in this region. to simulate the ice effects on waves, we first need to consider the length scale between 𝜆 and d (linton 2010), where d could be considered the diameter of ice floes and is the wavelength. for an ice sheet and grease ice where 𝜆 < d and 𝜆 >> sit, the sea ice can be modelled as a thin elastic ice layer where waves propagate under ice, and the ocean–ice interface is where the dissipation occurs. when 𝜆 ≈ d, wave attenuation is understood to be dominated by a conservative process known as the scattering mechanism, which was first observed by wadhams (1975). when 𝜆 > d, waves propagate through smaller sea-ice floes, and dissipation occurs in many forms (squire 2018); this type of ice cover can be modelled as a semi-infinite viscous ice layer, in which effective material properties can be tuned to reproduce the aggregate effect of various sea-ice effects on waves (squire 2018). the 𝜆 > d regime is primarily observed in the miz. this is the length scale of interest to our wave buoy observation because the ice charts indicated that the wave buoys were located near and in new and young ice, with typical thickness less than 30 cm, during the observation period (see supplementary material). for the purpose of a model–observation comparison, we used an operational model called arc mfc, with data from the specific product arctic_analysis_forecast_wav_002_014 downloaded on 18 january 2022. because the arc mfc model’s wave dissipation parameterization (sutherland et al. 2019) is suited for modelling waves in the miz thin ice cover, we expect reasonable model agreement with the observation. our objective in this study is to elucidate the predictability of the arc mfc wave–ice model in the central arctic ocean by applying the drifting wave buoy observations and two other model products: ecmwf hres (wave) and nextsim (sea ice). specifically, we focus on how sea-ice edge and sit representations in the sea-ice forcing affect wave predictions when new ice is forming. drifting wave buoy observation wave buoy sensor and platform description during the 2021 nabos campaign, we deployed the first prototype of the omb developed by rabault et al. (2022), to which we refer herein as the zeni-v2021, alongside a sofar spotter, herein referred to as spot-1386. both zeni-v2021 and spot-1386 buoys measure ocean surface motion, but they use different technology. the zeni-v2021 was recently introduced by rabault et al. (2022). the omb electronic components for detecting ocean surface motion are a 6 degrees of freedom accelerometer and gyroscopic imu manufactured by st (model ism330dhcx). the attitude heading reference system correction via sensor fusion of three-axis accelerations and angular rates produces true vertical acceleration (rabault et al. 2022), which is integrated twice to estimate the surface elevation. the omb ‘buoy’ is a sensor unit that is housed in a waterproof enclosure (e.g., figure a1 by rabault et al. 2022); it is not designed as a floating platform in water. the primary deployment method of ombs is that the sensor unit is placed on an ice floe, and the ice floe becomes the sensor’s floating platform (hence, the term “wave–ice buoy”). at the time of the buoy preparation, in july 2021, the sea-ice extent was low, nearly as reduced as the 2012 record low sea-ice extent. (however, by august, the sea-ice extent had plateaued, resulting in limited opportunities for open-water deployment. see arctic data archive system [2023] for sea-ice extent images.) an alternative deployment method was devised by housing the sensor in a floating platform. the ad hoc platform was a zenilite gps tracker enclosure, whose design allowed it to house the omb electronic components (see appendix b, rabault et al. 2022). the zenilite gps drifting buoy has a diameter of 340 mm, is 300 mm in height and weighs about 6 kg. spot-1386 is a commercially sold drifting wave buoy; it is a proven technology with thousands of them currently deployed in the world oceans. the dimensions are similar to the zenilite gps drifter, which are 420 mm wide by 310 mm high and weigh 5.3 kg (7.4 kg with a ballast); therefore, spot-1386 is an appropriate benchmark for zeni-v2021. spotters’ proprietary firmware uses a gps/gnss receiver to get the device horizontal and vertical displacements. buoy deployment the wave buoys were deployed adjacent to an ice edge in the central arctic ocean, north of the laptev sea (81.915°n, 118.763°e) at about utc 05:05 on 15 september 2021. the deployment location is shown in fig. 1, and the sea-ice conditions as observed onboard the ship on the day of the buoy deployment are shown in fig. 2. the spot-1386 battery life at high latitudes without a solar charge is approximately 10 days; as such, the co-located deployment duration only lasted between 15 and 29 september. the buoy tracks for this period are shown in fig. 1a, which is overlaid with the amsr2 sic (hori et al. 2012) contours. fig. 1 (a) the co-located wave buoys were deployed in the arctic ocean on 15 september 2021. (b) the zeni-v2021 and spot-1386 trajectories between 15 september (white dot) and 29 september are shown. the white crosses show approximate location when the visible inertial oscillation stopped on 25 september 2021, which could indicate a change in ocean surface conditions. the dashed and solid lines in (a) 15 september and (b) 25 september indicate the 0.15 and 0.80 amsr2 sic contours, respectively. fig. 2 sea-ice conditions encountered during the cruise on 15 september 2021 after the buoys were deployed: (a) grey ice and (b) grey-white ice, both belonging to the young ice category. the primary motive for the buoys being deployed at the same location was to validate zeni-v2021 against spot-1386, and we anticipated that the buoys would measure analogous wave signal for at least several days. for example, waseda et al. (2018) and nose et al. (2018) describe the trajectories and wave statistics of two buoys deployed at the same location in the ice-free beaufort sea in 2016; the buoys drifted along similar tracks for about 13 days, during which time, they measured analogous wave statistics. however, we observed that the zeni-v2021 and spot-1386 wave heights began deviating slightly merely 12 hours after the buoys were deployed. two days after deployment, wave heights and periods varied considerably between the two buoys, which indicates that the measured waves’ evolution did not occur entirely over open ocean, that is, sea ice affected how the waves evolved. co-located wave buoy measurements in thin ice field overview of the wave data. figure 3 presents an overview of the co-located buoy observation: the buoy distances, and wind, wave and sic conditions. here, wave statistics derived from the vertical surface elevation are significant wave height , where and wave periods (peak period tpˊ, which is the inverse frequency of peak s(f) and −1 moment period, also known as energy mean wave period, the notations are frequency spectrum s and frequency f. the integration range was (f0, f1) for n th spectral moments mn, where f1 = 0.308 hz. zeni-v2021 data were affected by the noise floor that was elevated whilst the buoy was drifting in open water until about 25 september; the elevated noise floor is analogous to the observation by waseda et al. (2017), waseda et al. (2018) and nose et al. (2018) and seems to accompany imu-based wave sensors housed in a relatively small floating platform. the same ideal filter method as used by waseda et al. (2017), waseda et al. (2018) and nose et al. (2018) was implemented to derive the wave statistics. as such, f0 was not a constant and depended on the ideal-filter cut-off frequency. the zeni-v2021 integration range (f0, f1) was matched in the spot-1386 wave statistics calculation. it is noteworthy that the elevated noise floor was observed until 25 september, which roughly coincides with the time when the inertial oscillation visible in fig. 1a seemingly stopped (figs. 1, 3). fig. 3 an overview of the co-located wave buoy measurements: (a) a time series of buoy distances; (b) the ecmwf hres atmospheric forecast wind vector extracted at the zeni-v2021 location; (c) the buoy significant wave height hm0; (d) energy mean and peak wave periods t0m1 and tp; (e) the amsr2 sic extracted at the buoy locations. the blue dotted lines indicate when the buoys’ hm0 began to deviate slightly. the white crosses correspond to the approximate times when the inertial oscillations seemingly stopped (fig. 1). inter-buoy comparison. it is apparent in the hm0 panel of fig. 3 that, despite the buoys having similar drifting trajectories for the first half of the deployment, hm0 began to vary slightly between them after half a day and considerably after just two days. as we will show throughout the paper, the variability likely indicates that the wave evolution was modified by the sea-ice fields via one of the following effects: (1) waves are attenuated as they propagate into the ice-cover medium; (2) lateral boundary conditions are imposed by the ice fields and affect the wave evolution over the effective fetch. although we discuss (below) the possibility that the effective fetch at the buoys’ location after 12 hours of deployment was already affected by the sea-ice lateral boundary, we aim to consolidate the general inter-buoy agreement when the buoys were in close proximity. scatter for hm0 and t0m1 is plotted in fig. 4. the markers were grouped by an arbitrary buoy distance threshold of 5 km to demonstrate that the buoys’ wave statistics agreed better when the distance between them was shorter, that is, the effect of the sea-ice field on wave evolution is less for shorter distances. indeed, the blue markers, indicating the data when the between-buoy distance was <5 km, in both panels are clustered closer to the black dotted agreement line than the red markers. furthermore, as was shown in the left panel of fig. 7 by rabault et al. (2022), the spectra agreed well immediately after the buoys were deployed. fig. 4 scatterplots of zeni-v2021 and spot-1386 from 15 to 25 september: (a) the hm0 (m) and (b) the t0m1(s). the date of 25 september was chosen to avoid comparing wave periods that were affected by the buoy noise floor (see the wave periods shown in fig. 3). the marker colours were grouped using an arbitrary buoy distance threshold: blue represents a distance less than 5 km and red greater than 5 km apart. the blue markers tend to cluster near the agreement lines (black dotted lines). whilst precise zeni-v2021 validation with spot-1386 was impeded by the growing sea-ice fields, we showed that the zeni-v2021 measurement quality seems sufficiently adequate when the wave evolution was less altered by the sea-ice field (when the distances between them were short). as such, we used the wave events observed by the co-located buoy measurements to evaluate the operational arc mfc wave–ice model predictability. numerical models arc mfc wave–ice model the wave–ice interaction parameterization. the arc mfc wave–ice model is an operational wave model product for the arctic ocean and includes a wave–ice interaction parameterization, that is, the model can simulate wave propagation in sea-ice cover. medium-range forecast and analysis are distributed via the cmems platform. the arc mfc wave–ice interaction is based on the work of sutherland et al. (2019). they modelled wave dissipation with a two-layer sea-ice model: the top layer is modelled like a thin film that has no horizontal motion with thickness (1-ε)hi, whilst the bottom layer is modelled as a moving viscous layer. here, hi is the ice thickness. sutherland et al. (2019) describe that the ε coefficient is related to ice permeability at the microscopic scale and is a function of ice temperature, salinity and ice volume fraction. the assumption of a highly viscous top layer is similar to weber (1987), who derived a well-known wave dissipation solution by modelling the thin ice cover as an inextensible layer that halts the horizontal motion of the fluid layer underneath. the model by sutherland et al. (2019) could be considered an extension of the weber (1987) model. in the latter, the dissipation rate is α ∝ k35f3.5 where k35 is a constant. the model by sutherland et al. (2019) also has a frequency dependence, but they also included an ice thickness dependence to the dissipation rate: α ∝ k40f4, where k40 is a function of ice thickness. a more thorough discussion on the various dissipation rates in the literature is provided by waseda et al. (2022). sutherland et al. (2019) developed their model on the basis of a scaling argument as they derived that the viscosity scales with sit, v ∝ hi, which led to spatial wave dissipation as a function of ice thickness and frequency: α ∝ hif4. the dissipation rate is parameterized in equation 16 by sutherland et al. (2019) as: where ∆0 ≈ 1. in the cmems quality information document (bohlinger et al. 2022), the dissipation rate is denoted as, α = cdhik2,where they state that cd is a tuning parameter and is determined by the best fit to the observation obtained from the ice-covered fjord, tempelfjorden, in svalbard, in 2018. note that when ε = 0 (or cd), the model may behave like the weber (1987) model if the boundary layer in the fluid is implemented (not done so in the model by sutherland et al. [2019], yet). lastly, the dissipation rate α is used to estimate the dissipated wave spectrum as follows: where s0 is the incoming wave spectrum and x is a distance between the two points. the wave part of the arc mfc wave–ice model is based on met norway’s version of wam (the wamdi group 1988). wam is a spectral wave model that is discretized in frequency and direction and solves the numerical evolution of ocean waves as energy budgets based on the action density balance equation. the surface wind boundary conditions are forced using the ecmwf hres atmospheric forecast. at the ocean boundary along 53°n latitude, wave lateral boundary conditions are directional wave spectra from the ecmwf hres wave forecast, also based on wam. the ecmwf hres atmospheric forecast has a regular longitude/latitude grid at 0.1 degrees. the arc mfc wave–ice model has a spatial resolution of 3 km on the polar stereographic projection. the sea-ice part of the arc mfc wave–ice model is taken from the arc mfc ocean analysis (the specific product name is arctic_analysis_forecast_phys_002_001_a). the sea-ice model is the community ice code and based on the viscous–plastic sea-ice rheology. the sea-ice model uses a one-thickness category sea-ice model based on the thermodynamics described by drange & simonsen (1996) and sakov et al. (2012). there, the minimum thickness for the newly formed ice is given as 0.5 m. implications of the minimum thickness value are evaluated with the buoy observations in a later section. the community ice code sea-ice model was coupled to the hycom. the atmospheric forcing is obtained from the ecmwf hres atmospheric forecast. the data assimilation was performed weekly, using the ensemble kalman filter (sakov et al. 2012), for the following: altimeter sea level, in situ temperature and salinity profiles, the ostia sea surface temperature, osi saf sic and drift observations, and the (winter) sit from the cryosat-2 and soil moisture and ocean salinity satellites. the hycom has a horizontal resolution of approximately 12 km, which is more than three times the resolution of the arc mfc wave–ice model. ecmwf hres wave forecast wave heights and periods from the ecmwf hres wave forecast were used in this study as a tool to analyse the arc mfc wave–ice model and the buoy observation comparison. the ecmwf hres wave forecast was obtained for our research activity by the arctic data archive system, tokyo, japan. we took a series of 0–24-hour forecasts to produce a time series during the observation period. the ecmwf hres wave model accounts for sea ice using ice masks where grid cells with sic > 0.30 are treated as land. the ecmwf hres wave forecast model has a regular longitude/latitude grid at 0.125 degrees. the ecmwf hres wave model is useful to evaluate the wave conditions in the open water near the ice edge based on the following premises. (1) when the wave evolution occurs entirely over the open water fetch, the ecmwf hres wave and arc mfc wave–ice models should agree. (2) near the ice edge, where satellite-derived sea-ice data are uncertain, inaccurate sea-ice representation can cause erroneous wave predictions (nose et al. 2020). (3) in such cases, the ecmwf hres wave model that neglects sea ice may produce better predictions. nextsim sea-ice model the nextsim sea-ice model (specific product name arctic_analysisforecast_phy_ice_002_011; rampal et al. [2016]; ólason et al. [2022]) is a sea-ice product distributed by the cmems and based on the brittle-bingham-maxwell rheology. rampal et al. (2016) introduced this model describing that fracturing and faulting of sea ice should be expressed as an assembly of plates >o(1 km) and floes o(100 m), rather than an intact solid plate. the nextsim thermodynamical component is based on a three-category model that includes open water, newly formed ice and older ice, as described by rampal et al. (2019). rampal et al. (2016) show that their model calculates ice formation in the category of newly formed ice on the basis of the atmosphere and ocean forcing, whereas a prescribed growth rate is conventionally adopted in classical models (rampal et al. 2016). the thickness range of this newly formed ice category is 0.05–0.275 m, which is considerably thinner than that of the arc mfc ocean analysis. unlike the arc mfc ocean model, nextsim is not coupled to an ocean circulation model but is coupled with a mixed-layer model that is relaxed to an ocean circulation model. the ocean part is represented by a single level “slab ocean” model of the mixed layer (rampal et al. 2016) and uses the following daily averaged forcing from the topaz4 ocean data assimilation model system: sea surface (0–3 m) ocean velocity, temperature and salinity, and the mixed layer depth (williams et al. 2021). the atmospheric forcing is the ecmwf hres atmospheric forecast, and the nextsim model assimilates osi saf sic via the nudging scheme on a daily basis. since the control variable is only the sic, nextsim is strongly constrained to the observation, that is, the osi saf sic. the model has a lagrangian triangular mesh with an equivalent square grid resolution of ca. 7 km, for which the data are distributed on the 3 km polar stereographic projection grid. the effects of sea ice on wave evolution as observed by the wave buoys and models sea ice as lateral boundary effects on wave evolution significant wave height hm0 and period time series were extracted from the arc mfc wave–ice model and the ecmwf hres forecast at the zeni-v2021 and spot-1386 positions during their deployment between 15 and 29 september 2021. the full time series for wave heights and periods are shown in supplementary figs. s2 and s3. in this subsection, we focus on the wave heights between 15 and 19 september immediately after the buoys were deployed in open water. following the deployment, the ecmwf hres hm0 agrees well with both buoys for up to ca. 12 hours, whereas the arc mfc hm0 is clearly underestimated (fig. 5). shortly after, however, the buoys’ hm0 takes a steep decrease at about 14:00 on 15 september (fig. 5), and the ecmwf hres hm0 is overestimated, whilst the arc mfc hm0 agrees qualitatively with the observation. this change coincides with the time when the zeni-v2021 hm0 began deviating slightly from that of spot-1386 (fig. 3). fig. 5 significant wave height hm0 time series comparing the models (grey and red symbols) with the (a) zeni-v2021 and (b) spot-1386 buoy observation (blue symbols) between 15 and 19 september 2021 when the buoy distances were generally less than 5 km after the deployment. the missing values in the ecmwf hres wave forecast are due to ice masks (grid cells with sic > 0.30). the pink bars indicate when the buoy observation agreed with the ecmwf hres wave forecast. the green arrows show when a sudden reduction in the wave heights was observed. the purple bars indicate when the buoy observation agreed qualitatively with the arc mfc wave–ice model. immediately after the deployment at 06:00 on 15 september, the arc mfc wave directions were primarily parallel to the ice edge (fig. 6a). tracing upwind from the buoys, the ice edge protrudes and shelters the buoys’ effective fetch on which waves can grow. considering the arc mfc hm0 is underestimated, the ice edge sheltering of the buoys may be the cause of the underestimation, that is, the protruding ice edge may not be an accurate representation of the sea-ice field. for comparison, supplementary fig. s4c shows the buoys are not sheltered by any protruding ice edge features in the ecmwf hres sea-ice representation. fig. 6 arc mfc wave fields showing how the fetch orientation of the zeni-v2021 and spot-1386 trajectories changed from (a) along the ice edge immediately after the deployment at 06:00 on 15 september 2021 to (b) off-ice by 00:00 on 16 september. colours indicate the hm0, whilst the grey vectors correspond to mean wave directions with the vector lengths scaled by t0m1. the sic contour lines are 0.15 (dotted), 0.30 (dashed) and 0.80 (solid). fig. 7 arc mfc ice and wave fields during the wave event on 29 september 2021 when zeni-v2021 measured ca. 1.3 m hm0, but the model showed no waves. (a) the wave conditions in which the colours indicate hm0, whilst the grey vectors correspond to mean wave directions with the vector lengths scaled by t0m1. (b) a zoomed-in view of (a) near the buoys. the sic contour lines are 0.15 (dotted), 0.30 (dashed) and 0.80 (solid). the fetch orientation transitioned from along the ice edge to off-ice wave conditions (fig. 6b) after the models’ trend reversed. (winds were also blowing from the ice cover [supplementary fig. s4b, d].) the ecmwf hres hm0 is clearly overestimated (fig. 6), and the arc mfc hm0 agrees with the observations with a varying degree of predictability. these observations demonstrate the lateral boundary effect that sea ice imposes on the wave fields. we conjecture that the inaccurate representation of the arc mfc ice tongue imposed a lateral boundary condition that prohibited reproducing the true wave evolution when the fetch was orientated parallel to the ice edge. a similar scenario was also observed on 21 september 2021, in which the ice tongue representations between the arc mfc and ecmwf hres models were markedly different. this event is described in the supplementary material to present further support to this conjecture. wave dissipation due to sea ice on 29 september south to south-easterly winds over the laptev sea generated on-ice waves on 29 september 2021. the model wave fields are shown in fig. 7. by this time, both zeni-v2021 and spot-1386 were in dense ice cover with sic > 0.8 (see fig. 3e). the ice edge geometry and wave orientation were not straightforward; the zeni-v2021 location was downwind compared to the spot-1386, but the zeni-v2021 distance to the ice edge relative to the wind direction was closer than that of spot-1386 (fig. 7). during this event, the ecmwf hres wave model has no values at both buoys as they are covered by the ice mask. the arc mfc wave–ice model simulates no waves at both buoys (supplementary fig. s2). however, the hm0 time series panel in fig. 3c depicts that waves were observed at zeni-v2021, reaching a peak hm0 value over 1.25 m. spot-1386 located ca. 30 km south-east of zeni-v2021 did not observe any waves. to investigate how the wave energy propagated to the downwind zeni-v2021, but not for spot-1386, we analysed the model representations of the sea-ice field of the arc mfc ocean analysis and the nextsim sea-ice model product. sea-ice model representation differences and their effects on wave evolution comparison of arc mfc and nextsim sea-ice field representations sea-ice fields between arc mfc and nextsim are compared at the buoys’ location on 29 september 2021 in fig. 8. it is apparent that the horizontal scale of arc mfc sea-ice features (fig. 8a, c) is effectively limited to the arc mfc ocean analysis scale of ca. 12 km. this may be expected as interpolation to a high-resolution grid is unlikely to reveal features less than the original scale; the implication here is that there is an inconsistent scale between the wave–ice model geographical configuration and the model physics resolution. the scale of sea-ice features in the nextsim sea-ice model appears to be much finer; the reason for this may be speculated that the lagrangian nature of the model can influence the thermodynamics as well as the mechanical properties. fig. 8 comparison of ice conditions on 29 september 2021 between the (a) and (c) arc mfc and (b) and (d) nextsim models. (a), (b) the sic; (c), (d) the sit. the sic contour lines are 0.15 (dotted), 0.30 (dashed) and 0.80 (solid). notwithstanding this, the striking differences between the two models pertaining to the buoys’ wave observation are the ice edge location, the 0.80 sic contour and the sit differences. the nextsim sic field shows that the distance from zeni-v2021 to the sea-ice edge is much closer than shown in the arc mfc field. moreover, if we take the wave propagation as roughly 150 degrees, then 0.80 sic ice-covered sea that the waves need to propagate to reach zeni-v2021 is much shorter than that of the arc mfc wave–ice model, whilst for spot-1386, this distance remains relatively similar. regarding the sea-ice edge and 0.80 sic contour differences between the arc mfc ocean analysis and the nextsim sea-ice model, we revisit the data assimilation intervals and scheme differences: the arc mfc ocean analysis assimilates data at weekly intervals and uses the ensemble kalman filter with many control variables (see the earlier subsection about the arc mfc wave–ice model), whereas the nextsim sea-ice model carries out daily data assimilation via the nudging scheme with sic being the only control variable (see the earlier subsection about the nextsim sea-ice model). the data here suggest that the differences in the data assimilation intervals and schemes produce diverging sea-ice field representations. the representation of sit in the arc mfc model for thin ice appears to be poor: the ice field beyond the 0.80 sic contour is practically sit > 0.3 m. by contrast, the nextsim sit field clearly has a thickness distribution between 0 m and 0.3 m within the plot domain. the supplementary material describes the observation-based ice chart that confirms the ice type near the ice edge, and the wave buoys were young ice. although it is beyond the scope of this paper to examine whether coupling a wave model with the nextsim sea-ice forcing reproduces the co-located buoy data, there is sufficient evidence to suggest that the nextsim sea-ice representation appears to be in accord for reproducing the zeni-v2021 hm0, that is, less dissipation because of low sics and thinner thickness. disparate scale between wave dissipation parameterization and the sit forcing the sit disparity between the two models at the regional scale indicates that the arc mfc sit representation up to 0.5 m is poor (supplementary fig. s6). sit is one of the most fundamental sea-ice variables, yet it remains difficult to measure as reliable methods are via ice core sampling, electromagnetic–induction instruments and select satellite observations (tateyama et al. 2006; tilling et al. 2018). in other words, regional/synoptic scale estimation of an sit field is typically not readily available. for wave–ice models, an implication is that ice thickness can often serve as a wave dissipation tuning parameter. for ocean–ice coupled models, the essential feedback of sea ice to the ocean is thermodynamics, which is rather insensitive to thin ice. as such, one of the tuning parameters may be the minimum thickness parameter; indeed, the arc mfc thermodynamic model is based on the work of drange & simonsen (1996), which has the minimum thickness of newly formed ice as 0.5 m. another possibility for the poor thin ice representation is the data assimilation method. the afc mfc ocean analysis is based on the ensemble kalman filter scheme (sakov et al. 2012) and does not assimilate sit in the summer months. as shown in the previous section, the ice field beyond the 0.80 sic contour in fig. 8 is practically sit > 0.3 m; it is plausible that arc mfc ocean analysis data assimilation may assume correlation between the observed sic and unobserved sit, which could be the cause of the poor thin ice representation. from the wave–ice interaction viewpoint, however, pancake ice thickness is typically 5–10 cm, and new and young ice thickness is less than 30 cm (wmo 2021). the arc mfc wave–ice interaction parameterization is based on the sutherland et al. (2019) two-layer model, which parameterized the wave dissipation rate to scale with the sit. accordingly, the poor representation of miz thin ice cover in the sea-ice forcing is a critical issue. it appears, on the basis of fig. 8 and supplementary fig. s6, that the arc mfc ocean analysis does not resolve the thin thickness distribution that is appropriate for the wave dissipation model of sutherland et al. (2019). according to equation 16 by sutherland et al. (2019), ε = 1 determines the maximum dissipation in the moving viscous ice layer as the maximum wave dissipation rates along the approximate wave propagation were plotted in fig. 9 for the wave period of 7 s to quantify the effects of sit differences between the arc mfc and nextsim models. the sit was extracted for 200 km along the approximate wave propagation ray from 121°e, 82.2°n on an initial bearing of 150 degrees. for relevance, tp= 7 s was roughly the upper limit of the co-located buoy observation when wave energy was detected (see fig. 3). for sit along the transect distance of 25–75 km, fig. 9 shows that the arc mfc wave dissipation rate can be three times than that of the nextsim counterpart. this figure confirms that the arc mfc ocean analysis ice thickness does not adequately resolve the thin ice to apply the dissipation model of sutherland et al. (2019); this prohibited a meaningful model–observation comparison to evaluate the sutherland et al. (2019) model with our wave buoy observation: can their sit-dependent dissipation rate reproduce waves in miz covered with thin ice? fig. 9 comparison of sutherland et al. (2019) wave dissipation rate , where ε = 1 based on the arc mfc and nextsim model sit hi. α is -plotted along a 200 km transect from 121°e, 82.2°n at an initial bearing of 150 degrees for waves with 7 s periods. the right axis is the sit. for completeness, we conducted an academic experiment to show how the exponential dissipation rate differs because of poor thin sit resolution. we used a pierson moskowitz spectrum with a 7.5 s tp that has a 2.2 m hm0. the dissipated hm0 was calculated from the spectrum s using eqn. 2. assuming a maximum dissipation rate over a 10 km distance with a thickness of 0.1 m and 0.5 m, we estimated hm0 = 0.1 and 0.6 m, respectively. the difference of for the 0.5 m thickness results in 2.6 times the dissipation than the 0.1 m thickness case. however, it is difficult to know how this is reflected in the arc mfc wave–ice model as the true sic field, the sea-ice edge, and the incoming spectra shape are all unknown. these considerations make it clear that the arc mfc wave–ice model overestimated the wave dissipation in the thin ice fields with sit less than 0.5 m during our buoy observation. the arc mfc wave–ice model in mizs near the ice edge needs sit forcing that can resolve the thin ice types. it is worth mentioning that the nextsim sea-ice model has been experimentally coupled with the wave model of boutin et al. (2021), though with a different viewpoint, their focus was the effect of waves on ice fragmentation utilizing the brittle rheology of nextsim. conclusions two drifting wave buoys were deployed in the central arctic ocean, north of the laptev sea, where there have not been any wave observations available. the motivation for the buoy deployment was to validate the zeni-v2021, a prototype of an experimental wave–ice buoy named omb (rabault et al. 2022), with spot-1386, a commercial wave buoy. the inter-buoy comparison showed that when the buoy distances between zeni-v2021 and spot-1386 were close, defined here with the arbitrary threshold of 5 km, zeni-v2021 was sufficiently accurate compared to the commercial spot-1386 buoy. as such, the buoy data were used to study the predictability of waves in the deployment region. the first event we focused on occurred shortly after the deployment, when a sudden decrease in the buoys’ significant wave heights hm0 from about 1.75 m to about 1.50 m was observed. the decrease coincided with the change in wind direction from along the ice edge to off-ice wind. the operational arc mfc wave–ice model product did not reproduce the sudden decrease because the ice tongue constrained the wave growth over the available fetch. the analysis here shows the resolution of ice edge features is critically important for accurate predictions of waves in the nearby open water. the second case we analysed was when the wave buoys entered ice cover as new ice formed in the area. during this event, zeni-v2021 located downwind of spot-1386 measured waves with a peak hm0 of 1.25 m, but spot-1386 did not detect any waves. the comparison of the buoy observation with the arc mfc wave–ice model revealed that the arc mfc wave–ice model largely underestimated the downwind zeni-v2021 hm0. to elucidate the model error, we examined the model sea-ice conditions between the arc mfc ocean analysis and the nextsim sea-ice model product. the analysis showed that the arc mfc sea-ice forcing does not resolve thin thickness distribution for ice types like new and young ice, which are typically less than 30 cm thick. since the arc mfc wave–ice model’s dissipation rate has an sit dependence, the arc mfc model overestimated wave dissipation in the thin thickness ice field. in contrast, nextsim seemed to resolve the thin thickness distributions in the miz. the model differences may be caused by new ice formation calculation methods and data assimilation schemes. regardless of the cause, the arc mfc wave–ice model needs sea-ice forcing that reproduces thin ice cover for accurate predictions of ocean waves in mizs when new ice is forming. reliable ocean wave forecasts are crucial for safe navigation in the polar seas. our study presents an observational insight into the coupling of wave and ice models for better wave predictions in thin ice-covered mizs. observations and models help us ensure sustainable developments, such as safe navigation, in the changing arctic ocean. acknowledgements the authors sincerely thank 2021 nabos chief scientist dr igor polyakov for supporting their wave buoy deployment. the authors are grateful to dr guillaume boutin and the anonymous reviewer for providing constructive criticisms during the peer review. their invaluable comments led to a much improved manuscript. the authors are also grateful to cmems for providing a data distribution platform. the authors also sincerely thank the model developers of the arc mfc wave–ice model and the nextsim sea-ice model products. references arctic data archive system 2023. amsr2 sea ice con. + sea surf. temp. + snow depth. accessed on the internet at https://ads.nipr.ac.jp/vishop/#/extent and plot 2012 and 2021 sea-ice extents on 5 may 2023. bohlinger p., carrasco a. & saetra ø. 2022. arctic ocean wave analysis and forecast product arctic_analysis_forecast_wav_002_014. quality information document issue 1.6. copernicus marine environment monitoring service. boutin g., williams t., rampal p., ólason e. & lique c. 2021. wave–sea-ice interactions in a brittle rheological framework. the cryosphere 15, 431–457, doi: 10.5194/tc-15-431-2021. drange h. & simonsen k. 1996. formulation of air–sea fluxes in the esop2 version of micom. technical report 125. bergen: nansen environmental and remote sensing center. hori m., yabuki h., sugimura t. & terui t. 2012. amsr2 level 3 product of daily polar brightness temperatures and product. version: 1.00. arctic data archive system (ads), japan. accessed on the internet at https://ads.nipr.ac.jp/dataset/a20170123-003 on 1 aug 2022. linton c.m. 2010. towards a three-dimensional model of wave–ice interaction in the marginal ice zone. journal of fluid mechanics 662, 1–4, doi: 10.1017/s0022112010004258. nabos. no date. nabos-ii. nansen and amundsen basins observational system. report of the nabos 2021 expedition. activities in the arctic ocean. iarc technical report 11. fairbanks: international arctic research center, university of alaska fairbanks. nose t., waseda t., kodaira t. & inoue j. 2020. satellite-retrieved sea ice concentration uncertainty and its effect on modelling wave evolution in marginal ice zones. the cryosphere 14, 2029–2052, doi: 10.5194/tc-14-2029-2020. nose t., webb a., waseda t., inoue j. & sato k. 2018. predictability of storm wave heights in the ice-free beaufort sea. ocean dynamics 68, 1383–1402, doi: 10.1007/s10236-018-1194-0. ólason e., boutin g., korosov a., rampal p., williams t., kimmritz m., dansereau v. & samaké a. 2022. a new brittle rheology and numerical framework for large-scale sea-ice models. journal of advances in modeling earth systems 14, e2021ms002685, doi: 10.1029/2021ms002685. rabault j., nose t., hope g., müller m., breivik ø., voermans j., hole r.l., bohlinger p., waseda t., kodaira t., katuno t., johnson m., sutherland g., johansson m., christensen k.g., garvo a., jensen a., gundersen g., marchenko a. & babanin a. 2022. openmetbuoy-v2021: an easy-to-build, affordable, customizable, open-source instrument for oceanographic measurements of drift and waves in sea ice and the open ocean. geosciences 12, article no. 110, doi: 10.3390/geosciences12030110. rampal p., bouillon s., ólason e. & morlighem m. 2016. nextsim: a new lagrangian sea ice model. the cryosphere 10, 1055–1073, doi: 10.5194/tc-10-1055-2016. rampal p., dansereau v., ólason e., bouillon s., williams t., korosov a. & samaké a. 2019. on the multi-fractal scaling properties of sea ice deformation. the cryosphere 13, 2457–2474, doi: 10.5194/tc-13-2457-2019. sakov p., counillon f., bertino l., lisæter k.a., oke p.r. & korablev a. 2012. topaz4: an ocean–sea ice data assimilation system for the north atlantic and arctic. ocean science 8, 633–656, doi: 10.5194/os-8-633-2012. squire v.a. 2018. a fresh look at how ocean waves and sea ice interact. philosophical transactions of the royal society a 376, article no. 20170342, doi: 10.1098/rsta.2017.0342. squire v.a. 2020. ocean wave interactions with sea ice: a reappraisal. annual review of fluid mechanics 52, 37–60, doi: 10.1146/annurev-fluid-010719-060301. sutherland g., rabault j., christensen k.h. & jensen a. 2019. a two layer model for wave dissipation in sea ice. applied ocean research 88, 111–118, doi: 10.1016/j.apor.2019.03.023. tateyama k., shirasawa k., uto s., kawamura t., toyota t. & enomoto h. 2006. standardization of electromagnetic–induction measurements of sea-ice thickness in polar and subpolar seas. annals of glaciology 44, 240–246, doi: 10.3189/172756406781811484. the wamdi group 1988. the wam model—a third generation ocean wave prediction model. journal of physical oceanography 18, 1775–1810, doi: 10.1175/1520-0485(1988)018<1775:twmtgo>2.0.co;2. thomson j., ackley s., girard-ardhuin f., ardhuin f., babanin a., boutin g., brozena j., cheng s.k., collins c., doble m., fairall c., guest p., gebhardt c., gemmrich j., graber h.c., hold b., lehner s., lund b., meylan m.h., maksym t., montiel f., perrie w., persson o., rainville l., rogers w.e., shen h., shen h., squire v., stammerjohn s., stopa j. & smith m.m. 2018. overview of the arctic sea state and boundary layer physics program. journal of geophysical research—oceans 123, 8674–8687, doi: 10.1002/2018jc013766. tilling r.l., ridout a. & shepherd a. 2018. estimating arctic sea ice thickness and volume using cryosat-2 radar altimeter data. advances in space research 62, 1203–1225, doi: 10.1016/j.asr.2017.10.051. wadhams p. 1975. airborne laser profiling of swell in an open ice field. journal of geophysical research 80, 4520–4528, doi: 10.1029/jc080i033p04520. waseda t., alberello a., nose t., toyota t., kodaira t. & fujiwara y. 2022. observation of anomalous spectral downshifting of waves in the okhotsk sea marginal ice zone. philosophical transactions of the royal society a 380, article no. 20210256, doi: 10.1098/rsta.2021.0256. waseda t., webb a., sato k. & inoue j. 2017. arctic wave observation by drifting type wave buoys in 2016. isope-i-17-569. san francisco, ca: international society of offshore polar engineers. waseda t., webb a., sato k., inoue j., kohout a., penrose b. & penrose s. 2018. correlated increase of high ocean waves and winds in the ice-free waters of the arctic ocean. scientific reports 8, article no. 4489, doi: 10.1038/s41598-018-22500-9. weber j.e. 1987. wave attenuation and wave drift in the marginal ice zone. journal of physical oceanography 17, 2351–2361, doi: 10.1175/1520-0485(1987)017<2351:waawdi>2.0.co;2. williams t., korosov a., rampal p. & ólason e. 2021. presentation and evaluation of the arctic sea ice forecasting system nextsim-f. the cryosphere 15, 3207–3227, doi: 10.5194/tc-15-3207-2021. wmo 2021. sea-ice information and services. wmo 574. geneva: world meteorological organization. late quaternary glacial and environmental history of kongsaya, svalbard olafur ingolfsson, finnbogi rognvaldsson. helene bergsten. lars hedenas, geoffrey lemdahl. juan m. lirio and hans petter sejrup ing6lfsson, 0.. rognvaldsson, f., bergsten. h . . hedenas, l., lcmdahl, g . , lirio, j . m . & sejrup, h . p. 1995: late quaternary glacial and environmental history of kongsoya, svalbard. polar research 14(2), 123-139. on western kongsoya. svalbard. three coarsening-upwards sequences of marine to littoral sediments, separated by tills, are recognised in sections at ca 50-92 m above present sea level. these sequences show major glaciations in the northern barents sea, resulting in substantial glacioisostatic downpressing of kongs0ya. till fabrics indicate ice movements controlled by the local topography. while glaciotectonic deformations suggest that ice moved from an ice divide northeast of kongscaya. independent of the local topography. the stratigraphical evidences show two pre-holocene ice-free periods, when the climate was similar to or slightly warmer than at present. the age of these periods is not clear. it is suggested that the elder ice free interval is older than isotope stage 5c. the younger ice free interval could be of eemian or early weichselian age. the uppermost succession of sublittoral-littoral sediments is of early holocene age. it relates to the high ( r l o o m ) postglacial marine limit, dated to approximately 10,ooo bp. dlafur lngolfsson and helene bergsten, earth sciences cenire, university of goieborg, guldhedsgaran 5a. s-413 81 goteborg. sweden: finnbogi rognualdsson, fjolbrautarskoli vesiurlands, is-300 akranes, iceland; lars hedeniis, deparimeni of crypiogamic botany, swedish museum of naiural history, box 50007. s-104 05 slockholm, sweden: geoffrey lemdahl, deparimeni of quaiernary geology. lund university. tornauagen 13, s-223 63 lund, sweden; juan m . lirio, instituio anrrirrico argeniino. cerriio 1248. i010 buenos aires, capiial, argentina; hans petter sejrup, geological institute, uniuersiij of rergen, allegi. 4 1 , n-5007 bergen, norway. introduction k o n g s ~ y a (191 km2) is the largest of a number of islands comprising kong karls land in the easternmost part of the svalbard archipelago (fig. 1a). the island is mainly made up of jurassic and early cretaceous strata, and the low ( ~ 3 0 0 m) mountains on eastern and western kongsoya (fig. 1b) are erosional remnants of a cretaceous plateau, capped by basaltic lavas (smith et al. 1976). quaternary sediments mainly occur below 100 m a.s.1. (salvigsen 1981). the purpose of the present investigation has been to locate and study pre-holocene glacial and marine sediments on the western part of the island. preliminary results were reported by ing6lfsson et al. (1992), rognvaldsson (1992) and ingdfsson & lirio (1993). previous studies geological observations were begun when pike (1898) and nathorst (1901) described raised marine beaches on the island and reported finds of driftwood at levels up to ca 40 m a.s.1. the idea of a glacier occupying the barents sea basin was first suggested by de geer (1900). nathorst (1901), who observed striated boulders on the plateau between retziusfjellet and tordenskjold berget (fig. lc), suggested that a nordaustlandet glacier could have covered the barents shelf as far east as franz josef land. stromberg (1972) found glacial sculptures almost totally lacking on western kongsaya. he discovered glacial striae at two localities, at high levels above cirques on sjogrenfjellet and tordenskjoldberget (fig. 1c). stromberg mapped the directions of glacial striae as indicating ice movements from ssw-sse and concluded that most probably the striae were formed by former local glaciers of modest extent. schytt et al. (1968) and hoppe (1972) used the kongscdya striae when reconstructing an extensive weichselian barents ice sheet, with an ice divide somewhere to the south-southeast of kongs~ya. knape (1971) reported driftwood from raised beaches up to 3 6 m a.s.1. and pre-holocene marine shells from altitudes up to 89 m. the drift wood samples were 14c dated and used for con structingan uplift curve (schytt et al. 1968; hoppe 124 olafur ingolfsson et al. i svalbard 1w km 0 o i western kongswa 0 5 k m f ; g . 1 . a : svalbard location map. localitieb mentroned in the t e x t : ( 1 ) breggerhalveya; (2) kapp ekholm; (3) linnedalen; ( 4 ) ski1vika;bellsund. b : the general phvsiography of kongseya. c: western kongseya. the location of raised beaches is shown as an approximation of areas where beach ridges occur rather than location of individual ridges. 1972). indicating that beaches below 36 m were younger than 7000 bp boulton (1979) suggested that there were two sets of beaches on k o n g s ~ y a , a lower holocene set, and a higher >40,000 bp set extending to the marine limit at 100m. he suggested that kong karls land had not been glaciated except by small glaciers during the late weichselian. salvigsen ' (1981) published new radiocarbon dates from kong karls land and presented an emergence curve for eastern kongs qya. he showed that a shoreline displacement of more than 1 0 0 m had taken place during the holocene, and his emergence curve is the strong est evidence presented for a late weichselian barents ice sheet over k o n g s ~ y a . marine geo logical data from the barents shelf (elverhbi & solheim 1983; vorren et al. 1988; elverhai et al. 1990; solheim et al. 1990; polyak & solheim 1994) show glaciations several times during the pleistocene. geomorphic features on the sea floor in the northern barents sea, some 150 km south of kongs@ya, are interpreted as fluted surfaces and de geer moraines, thought to show that the barents shelf had been covered by a sliding temperate glacier, at least in the observation area (solheim et al. 1990; elverhai et al. 1990). although the existence of a large late weich selian ice sheet covering the northern and central barents sea area is now generally accepted, its extension, thickness and duration are still dis cussed and debated (e.g. mangerud et al. 1992; elverhh et al. 1993; forman et al. 1995; lambeck 1995; siegert & dowdeswell 1995). forman (1990) described the spatial variation in emer late quaternary glacial and environmental history of k o n g s ~ y a , svalbard 125 gence records from svalbard, and concluded that the uplift pattern in nordaustlandet, the islands in the barents sea and on central and western spitsbergen, reflect glacial loading of the barents ice sheet during the late weichselian. this con clusion strongly indicates that the same ice dome or separated ice domes i n dynamic equilibrium have caused the isostatic depression observed. thus, almost synchronous interglacial/inter stadia1 events in the whole svalbard area could be expected, provided that this pattern of emer gence is valid for earlier deglaciations. mangerud et al. (1992) concluded that prior to the late weichselian glacial build-up, the barents ice sheet was small or non-existent, and that glaciers on and around svalbard were not much larger than today when the advance to the last glacial maximum started sometime after 25,000 bp. methods the stratigraphic investigations were concen trated at t w o main localities, the col of hidden and in the bogen cirque (fig. 1c). the sites were spotted by shell fragments in scree, and then cleared by digging. elevations of sections and of raised beaches were surveyed by repeated measurements by air-hb-1a electronic alti meter and some were levelled by theodolite. samples were collected for analysing grain-size, plant and insect macrofossil content, foraminifera and mollusc, species, thermoluminiscence (tl) and 14c determinations and amino acid diagenesis. the i4c age determinations were performed at lund university’s radiocarbon laboratory, and the tl-dating was carried out at the nordic laboratory for lurniniscence dating in ris0, denmark, using sand-sized potassium feldspars. amino acid diagenesis was measured in the protein matrix of fossil molluscs at the bergen amino acid laboratory, following the procedure described by miller et al. (1983). glacial morphology glacial sculpturing and erratics the landscape of kongsoya (fig. 1b) indicates that basal sliding and glacial erosion occurred when the island was completely covered with ice. on western kongsoya the glacial erosion is con centrated in shallow cols, valleys and cirques, leaving the plateaux relatively unmodified. the plateaux of hirfagrehaugen, retziusfjellet, tor denskjoldberget and sjogrenfjellet, as well as basaltic bedrock outcrops at lower altitudes, have been searched for glacial sculpturing, striae and erratics. the basalt plateaux are deeply weath ered, and no clear glacial sculpturing is evident. usually the surface is covered with regolith and crude soils. i n a few localities bedrock outcrops show stoss-and-lee topography, but none were found to carry glacial striae. the only erratics found on the plateaux were remains of petrified cretaceous tree trunks, probably eroded by the glacier from the local sedimentary bedrock and only transported a short distance. raised beaches and the marine limit the marine limit on western kongs~ya is at 94 98 m a.s.1. (fig. lc), which is in good agreement with knape’s (1971) results. the highest beach ridges on h ~ g s l e t t a were levelled to ca 100m a.s.l., which is about 10 m lower than salvigsen’s (1981) marine limit on eastern kongsoya. sal vigsen & nydal (1981) found that isostatic uplift has been greater in the eastern than in the western part of kongsoya during the last 7000 ijc years, and they took this as an indication of a late weichselian ice centre east of kongsoya. the material in raised beach ridges on western kong soya is primarily of local basaltic provenance, but crystalline rocks, granites and gneisses, are also found. these have probably been carried to the island by sea ice. the beach ridges at altitudes between ca 40 m and 60-70 m a.s.1. on h ~ g s l e t t a , formed between ca 9000 bp and 7000 bp (salvigsen 1981), are composed of well-rounded cobbles and boulders, with little gravel or sand, while the finer grain sizes are more characteristic for beach ridges above and below. this could indicate a higher energy in the coastal environment and less annual sea-ice cover during the formation of intermediate altitude beach ridges. this is supported by the lack of driftwood on beaches above 35-40 m. glacial stratigraphy of hidalen fluvial erosion in hidalen (fig. 1c) has exposed late quaternary sediments resting on triassic and lower jurassic bedrock. knape (1971) 126 olafur ingolfssorz et a / . m a.s.1. 90 85 80 75 70 65 60 55 50 48 15-31 lithology 0 sand silt gravel massive diamicton stratified el diamicton intraclasts m sedimentary structures lamination r;;l load deformation contacts sharp i y erosional i sheared fossils i in silu shells p paired shells w whole shells i shell fragments directional features c3 glaciotectonic orientation -. fabric orientation 15-30a e ,/' i , "v k;" dl / i , ,,' / ..... , i 15-30 b ' i fig. 2. lithostratigraphy of the hidalen sites. ,/' ' a 1 fig. 2. lithostratigraphy of the hidalen sites. reported shell samples of >38,000 and >jo,000 bp from 89 and 67 m a d . from scree on the northern side of hidalen. we found shells. both whole and fragmented. in scree, at a number of localities. four sites (numbered 15-30a. 15-30b, 15-30c and 15.31) were investigated in detail. and one additional site (14-03) was briefly surveyed and sampled. t h e lithostratigraphy of each site and correlations between sites are shown on fig. 2 . a cross section of t h e hidalen stratigraphy, with location of sites studied, and correlation between sites is shown in fig. 3. late quaternary glacial and environmental history of kongsgya, svalbard 127 fig. 3. a cross section of the hidalen stratigraphy, with location of sites studied. w e unit a unit a is the 'lowermost stratigraphical unit in hidalen. it is only exposed in section 15-30c. it is a 0.4 m thick massive, compact, silty-sandy diamicton. striated clasts were recognised in the diamicton. its lower contact to the stratified, unli thified jurassic sand is sharp but deformed. len ses of the sand have been incorporated into the diamicton and smeared out, and wedges of dia micton have been thrust into the substratum. the deforming force came from an easterly direction. the diamicton is interpreted to be a till. unit b unit b consists of a number of lithofacies, recog nised in sections 15-30a, 15-30b and 15-30c, which are interpreted to have been deposited in a marine environment. in the lower part of the unit, laminated silts and sands and massive silts, with occasional outsized clasts, dominate. con tacts between lithofacies are usually conformable, sometimes loaded. the thickness of the low ermost silty-sandy facies of the unit is 1-3 m. mollusc shells, fragments and some whole, were sampled from a sandy-gravelly lag-horizon in sec tion 15-30b. this part of the unit is interpreted as a stratified glaciomarine deposit, with dropstones. in the middle part of the unit, stratified dia mictons and massive or laminated sands domin ate. the diamictons carry numerous pebbles and cobbles, but a fabric studies did not reveal any preferred orientation of clasts (fig. 4a). occasional thin intrabeds of gravels occur, as well as pebble and cobble clasts. ruptured and bent substratum below a clast, indicating drop, was noted at two sites. shell fragments were sampled from one of the diamictons, but could not be identified to species. this part of the unit is inter preted to be a sublittoral glaciomarine sediment, influenced by meltwater input and slumping. its thickness in the sections is 1-2 m. in the upper part of the unit. massive diamic ton, gravel and sand with many pebbles and cobbles, occur together with laminated sand and silt. the massive diamicton facies has a thickness of 0 . 7 m , and consists of a silty-sandy matrix carrying rounded t o sub-angular pebbles. it has a sharp to erosional lower contact to the laminated facies below. the massive gravel and sand facies is about 0.25m thick. it grades upwards from granules and coarse sand to coarse and medium sand. its lower contact is erosional. the massive bed grades into interstratified, laminated sand and silt, with occasional granules and pebbles. together, the lithofacies indicate decelerating flow during deposition from a meltwater current entering the sublittoral environment. the upper most lithofacies in unit b, found only in section 15-30b, is a thin bed ( ~ 2 0 c m ) of well-sorted, planar cross-bedded sand. it has an erosional lower contact and carries shell fragments. it is interpreted as a littoral deposit. unit b in section 15-30a is heavily gla ciotectonised, and a tight, recumbent syncline has developed (fig. 5) below a thrust plane. the fold 128 (ilnfur ingciltnon et al. a n unit b, site 15-30a n: 25 v l : 295°130s1: 0.557 b n unit c, site 15-31 n: 27 v l : 111°17"s1: 0.808 c n unit e, site 15-30a n: 28 vi: i 3 2 ° ~ 1 0 s i : 0.752 fig 4 fabric analvre.; from western kongsaya. a . fabric from a diamicton tacies in unit b. s ~ k 15-30a: b : fabric from unit c a t site 15-31. c. tnhric from unit e at site 15-30a. axis trend nw-se. and the fold reflects over folding towards the southwest. with ice move ments from t h e northeast. molluscs and foraminifera. t h e mollusc fauna of unit b is p o o r , with only three species recognised (table 1), and it can only be used to confirm a marine environment. all shells and fragments a r e of large, robust individuals. fifteen samples from section 15-30a were prepared for foraminifera content, but none were found. six samples pre pared from section 15-30c, yielded three speci mens of benthic and o n e specimen of planktonic foraminifera (table 2). t h e specimens were worn and fragmented, and could not b e identified t o species. t h e almost total absence of foraminifera as well as juvenile and smaller molluscs in t h e sediments could be the result of dissolution. plant macrofossils. o n e sample from unit b, section 15-30a. was analysed for plant mac rofossils a n d was found to contain o n e fruit of pondweed (pontarnogeton), together with a num ber of unspecified leaves, as well as bryophytes (table 3). wetland a n d moist heath bryophytes are well represented i n this sample, comprising aitlacomniicrn turgidum, drepanocladus (s. str.) s p . , philonotis fontana/tomentalla, pohlia wah lenbergii a n d tayloria sp. drepanocladus species usually occur in nutrient-enriched environments. philonotis species and p . wahlenbergii grow in moving water. brachythecium reflexurn, cer arodon purpureus, hylocomiurn cf. splendens and pogonatum occur in mineral-poor places. brachythecium reflexurn and hylocomium indi cate stable ground, whereas most of the other taxa indicate m o r e unstable conditions, with a sparse cover of vascular plants. sanionia ortho thecioides is today a coastal plant in northern e u r o p e and svalbard, reaching southwards t o southern finland, sweden, norway and scotland (hedenas 1989; long 1992, 1993). it is typically found in shore meadows and rock crevices. t h e species recorded from unit b still occur on svalbard. t h e few remains of vascular plants and the moss record show a poor vegetation of phan erogams during the period when unit b was deposited. t h e wetland bryophytes and those of drier habitats indicate that a large part of the environment was mineral-poor, in contrast with the mineral-rich conditions usually found in peri glacial environments or in areas which have recently been deglaciated (miller 1987; hedenas late quaternary glacial and environmental history of kongs@ya, soalbard 129 fig. 5 . site 15-30a in hidalen. the section is orientated e (lefl) 10 w (right). 1992, 1994). thus, the bryophytes suggest an environment where the minerals have been lea ched out, which could suggest that the ground had been ice free for a considerable period of time. unit c unit c is a massive, silty-sandy diamicton, with abundant rounded to angular pebbles and cobbles and some shell fragments, recognised in sections 15-30c and 15-31. its thickness is 0.6-1 m in the sections. striated clasts occur, and a fabric study at site 15-31 (fig. 4b) showed preferred orien tation of clasts with dip towards ese. the lower contact of the unit is erosive and sheared, and unit b below is at places sheared and folded below the contact. in a small, overturned anticline at the contact between units b and c in section 15 31 the axial plane dipped towards northeast and the fold axis trended nw-se, indicating that the deforming push came from the northeast. unit c table i . subfossil molluscs from western kongs0ya. identified by s. funder site unit 15-30b 15-30c 15-31 14-03 23-01 b d d d bivalvia chlamys blandrca serripes groenlandicw macoma calcarea 1 hiatella arcrica f mya truncata f echinodermata srrongylocentrorur droebachensis cirripedia balanw balanw c f f c 1 1 1 f 2 f f f s f c 5 2 f frequent (>20 valves/fragments); c: common (11-20); s: scarce (4-10); 1-3: rare (number of valves/fragments). 130 olafur ingolfsson et al. table 2. foraminifera1 species recorded in samples from units b and d in hidalen. the upper number of each species refers to the actual number of counted specimens in the sample while the lower number refers to number of individuals when related to loog of dry sediment. identified by h . bergsten. sample number 95-427 95-407 95-409 95-422 95-424 95-430 95-434 95-437 site 15-30c 15-30c 15-30c 15-30c 15-30c 15-3oc 15-31 15-31 unit b b b d d d d d species asrrononron gallowav i loeblich & tappan buccella hannai arctica voloshinova carsrdulrna renrforme norvang elphidrum asklundr brotzen elp hidrum exca uatum (terquem) havnesrna orbiculare (brady) islandrella helenae feyling-hanssen & buzas reophax (p sprroplectammina bifornilr (parker & jones) verneulrna urciicu hoglund vdrid mlcareou\ , p r ~ i e s varia. agglutinated species planktonic foraminifera no of benthic foraminifera in the sample n o of specimens related to 100 g 5edirnent (dried) 1 2 1 1 1.9 22 22.9 1 1 164 170 7 1 1 . 1 21 5 4 3 21 9 58.2 3 8 1 8 . 3 1.1 1 1 1 1 1 . 1 1 1 1 2 217 56 5 0 . 7 1 2 216 60.3 5 4 154 4 . 8 171.6 2 2 . 2 21 2 3 . 4 2 2 . 2 1 1 . 2 2 2 . 2 34 86 40.5 9 5 . 9 1 1.1 6 11.1 6 5 7.1 5 6 4 1 4 . 7 11 5 i n 54 284 6 4 . 3 316.5 is interpreted to be a lodgement till, deposited by a glacier flowing from the east through the hidalen col. the till fabric indicates that the deforming push came from the southeast. while the sub-till fold geometry shows an ice movement from the northeast. we suggest that the deform ation took place under a thick ice flowing across k o n g s ~ y a from the northeast and that the till fabric indicates ice push through the hidalen col and relates t o a later deposition phase. with thin ner ice and topographically controlled iceflow. unit d unit d is a facies association of laminated silts and sands. overlain by cross-stratified sands and gravels and cobble-gravels, reflecting a shal loaing-upwards, marine t o littoral sediments t h e thickness of the unit is 5-8 m in sections 15-30c and 15-31, respectively. t h e lowermost 2-3 m are a succession of laminated sand and laminated to massive silt. contacts between lithofacies a r e usually conformable, s h a r p or graded. thin intra beds of well sorted sand and lags of granules and pebble gravels, with erosive lower contact, occur scattered in the unit. t h e laminates sand and silt facies carry mollusc shells (table l), paired as well as single a n d fragments, and single shells and fragments also occur in t h e sandy intrabeds. this part of the unit is interpreted t o be a sublittoral sediment. lag horizons and intrabeds of sand were caused by current activity and small scale slumping. t h e sublittoral sediments a r e discordantly over lain by a 1.5-4 m thick deposit of cross-stratified gravels and sands. t h e gravels a r e alternatively late quaternary glacial and environmental history of kongseya, soalbard 131 clastand matrix-supported, and pebbles are usually well rounded. the unit grades upwards from pebble gravels at the base to cobble gravels at the top. shell fragments occur throughout the unit. a 1.5 m high section was excavated in the mouth of the hidalen valley, at 72 m a.s.1. (section 14-03), consisting mainly of angular to well rounded clast-contact cobbles and boulders, with a silty-sandy matrix. the matrix contains abun dant fossil molluscs with many large, paired indi viduals of chlamys islandica (table 1). the sediments are similar to those in the present day beach ridges, where paired valves of c. idandica are also frequent. it is concluded that this part of unit d was deposited as a beach foreset, under similar conditions as the present, with seasonal open water and substantial wave action. molluscs and foraminifera. the mollusc fauna of unit d is poor, with five bivalve and one echino derm species and fragments of balanus balanus (table 1). as with the fauna from the underlying unit b, the shells are biased towards large and thick individuals and the species composition does not define any clear mollusc community. the presence of chlamys islandica does. however, show that the marine environment was influenced by atlantic water. c. islandica is present around kongsoya today, but does not enter high-arctic waters. foraminifera1 specimens were found in five samples from unit d (table 2). both calcareous and agglutinated species were noted. many speci mens were fragmented or showed surface wear which could be the result of dissolution and dia genetic effects. the most abundant species are lslandiella helenae, verneuilina arctica, astronion gallowayi, buccella hannai arctica and cassidulina reniforme. when comparing the foraminifera1 faunas of unit d with those previously reported from svalbard (feyling-hansen & ulleberg 1984; miller et al. 1989; nagy 1984; lycke et al. 1992), the unit d sediments contain a comparatively poor fauna. however, the species in unit d occur at many other svalbard sites, and are also found in the recent fauna (hansen & knudsen 1992). the faunas of unit d indicate seasonally open water, with marine conditions resembling those of today. plant and insect rnacrofossils. four samples from unit d in hidalen were analysed for plant and insect macrofossil content (table 3). remains of bryophytes dominate the record, just as in unit b . the samples from unit d were slightly richer in remains of vascular plants than unit b, and insect remains were also found. among the vas cular plants, potamogeton jiliformis is an aquatic growing in eutrophic but clear shaliow water on sandy or gravely bottoms (mossberg et al. 1992). it is widespread with an almost circumpolar dis tribution, but it is not found growing on svalbard today (hultcn & fries 1986; r ~ n n i n g 1979). selaginella selaginoides grows on wet calcareous ground such as spring mires and along the borders of brooks and lakes. it is circumpolar with a northern distribution limit along the arctic coast of scandinavia, russia, siberia, and alaska, where it is found up to the low arctic zone. it is not found today on svalbard (hultcn & fries 1986; mossberg et al. 1992; r ~ n n i n g 1979). among the four taxa of insect, rove beetles (staphylinidae) of the genus stenus are usually found along the margins of water or other wet places (harde 1984). the larvae of caddis flies (trichoptera) are mainly found in fast moving streams, rivers and ponds. the larvae of midges (chironomidae, diptera) are also mainly aquatic. and many of them live in the muddy bottoms of lakes (fitter & manuel 1986). the diversity of the present insect fauna on svalbard is very low, and neither beetles nor caddis flies have been recorded on kongsoya (danielsson pers. commun. 1994). two of the vascular plants as well as two of the identified insect taxa have a more southerly distribution today and are not found on svalbard, which suggests that the cli mate was slightly warmer than today when unit d sediments were deposited. the bryophytes were badly preserved and few fragments could be identified to species. among those, wetland plants were very. sparse, com prising aulacomnium turgidum, plagiomnium ellipticum, pseudocalliergon brevifolium , scor pidium cossoni and warnsto@a sarmentosa (table 3). pseudocalliergon brevifolium and s . cossoni are found mainly in mineral-rich to cal careous wetland environments, a . turgidum grows mainly in intermediately mineral-rich or sometimes rather mineral-rich places. warnsrorfia sarmentosa is a species of intermediately mineral rich habitats, in springs or in spring-influenced environments, whereas p. ellipticum is found in different wet and not too mineral-poor environ ments. most of the identified taxa indicate unstable, open habitats with a sparse cover of 132 o h f u r lngolfsson et al. table 3. vascular plants. insects and bryphytes found in samples from hidalen and bogen. western kongsaya. vascular plants and insects identified by g . lemdahl. bryophytes identified by l. hedenas. the nomenclature of mossberg et al. (1992) is used for the vascular plants. whereas the nomenclature for the bryophytes generally follows soderstrom et al. (1992). site' unit 15-30a 15-30c 15-31 23-01 hidalen hidalen hidalen bogen 5 d d taxon salis sp selaginella selaginoides poramogeron filiformis carex sp cerasrium sp papaoer sp. poramogeron sp. unspecified leaves unspecified wood srenui sp. staphvlinidae indet. tnchoptera indet. ambl~sregraceae sp. aulacomnrum polwrre aitlacomnrum rurgidimi barrramia irhyphglla brach,vlhecium reflexurn brachytltecium trachvpodium brvoenrhrophdlum recuriirosrrum b r w m cf pseudotriquerrum bryunr sp c'erarodon purpurew dicranella 5p. dicranum cf. m a j w dicranum cf. scoparium dicranaceae sp disrichium s p . dirrirhum flexicaule drepanocladrcs s . str. cf. grimmio sp. hylocomrirm splendens (incl. h. alaskanum) hylocomr~tm cf. splendens (incl. h. alaskanum) hypnum hambergeri hypnum rei~olurum cf. lophozia hyperborealpoerkei lophozia sp,. oncophorw uirens philonoris fonranolromenrella plagiomnium ellipricum pogonarum dentarum pogonarum dentarumlirrnigerum pogonarum/polyrrichum sp. pohlia wahlen bergii pohlia cf. wahlenhergii pohlrn sp polyrrichaceae sp. polytrichasrrum alpinum poi.vtrichashum sexangulare polytrichastrum/polynichum sp. polytrichum commune (incl. p. jensenii) polyrrvchum hyperboreum polytrichum junipcrinumlsrricium polvrnchum s p . potfiaceae s p . pseudocallrergon hreuifolium racomirrium sp. 1f + 3s l s + 1l 1 s 3 s i s 1 s + 2l 1 s 1 s 11ms if 1s 1 mts + lc is + 2l 1s + 2l 1 s is lis is 8s 12s +tw.w 5 ms 3m5 1f 15 ++ + 1 as +lc 21 85 25 31 11 15 h35 4s+ 1l 5s + 2l is 15 2 s + 3l i s + 1l 15 15 1 s 25 1 s + i b zs/b 15 15 15 1s 11 2l 2 s 1s 1 s zs i l 1 s 1 s i 2l 7s + 5l 1 s + 1l 4l 3l l s + i l 1s/b 2s 11 20s/3l* 25 35 1s+ 1l zl 35 15 15 15 1s + 1l 11 35 15 late quaternary glacial and enuironmentul history of k o n g s ~ y u , svulbard 133 table 3. (continued) site 1 5 3 0 4 15-30c 15-31 23-01 hid a i e n hidalen hidalen bogen unit b d d sanionia urthothecioides saniunia cf. orfhotheciuides sanionia uncinata cf. sanionia uncinafa sanionia sp. scurpidium cossoni sframinergon srramineum tayloria sp. torfula sp. warnsturfia exannulata warnstorfia sarmenfusa indet. akrokarp indet. pleurokarp indet. perigonium indet. 1s 1s/b 1s 1b 1s/b 3s 1s 3 s 4s 2s 1l 6 s + 1l" ls/b 11s 13s 2 s i t 1 s 5s/b + 1l 2s 1s 1l s = shoot; b = branch: l = leaf; ms = megaspore; f = fruit; tw = twigs; w = wood; s = seed; mts = metasternum; lc = larval case; th =thorax; relative frequence, + = 1-10, ++ = 10-100. twith antheridia and paraphyses. *these 2 0 stems and leaves were not checked for species identity (no transverse sections made). **most of the shoots are of the same phenotype as is usually found in the large late snow-beds in the scandinavian mountain range today. vascular plants. some taxa, such as .bryoer ythrophyllum recuruirostrum, distichium sp., ditrichum flexicaule, hypnum bambergeri and h . reuolutum are typical of mineral-rich to calcareous environments, whereas bartramia ithyphylla. ceratodon purpureus, pogonatum dentatum, polytrichastrum alpinum, the poly trichum species and racomitrium sp. are either found in poorer habitats or have a rather wide range as regards the mineral status of the habitat. the moss species found in the present study still grow on svalbard, except for pseudocalliergon breuifolium, which has its closest locality in the scandinavian mountain range. unit e unit e discordantly overlies unit d. it is a 0.5 m thick, sometimes matrix supported and some times clast supported, massive diamicton. it car ries striated, angular clasts and shell fragments. at places it is a massive deposit of clast-contact, angular boulders, with silty-sandy matrix. a fab ric analysis showed preferred orientation of clasts in a southeast-northwest direction, with dip towards the southeast (fig. 4c). it was observed in section 15-31 and on top of section 15-30a. it is tight and compact and conducts groundwater on its upper surface. it could be followed as a moisture-bearing horizon in the walls of the hidalen ravine from section 15-31 towards and over section 14-03. it is interpreted to be a till from a glacier that has moved through the hidalen col. from east towards west. unit f unit f is a 0.5 m thick deposit of stratified fine to coarse sand with silt laminae, interpreted as sublittoral sediments, which are in turn dis cordantly overlain by a 8-10 rn thick deposit of cross-stratified sands and gravels. the base of the unit is at 79 m a.s.1. the unit is upward coarsening, from sand and pebble gravels at the base of the cross-stratified facies, to cobble gravels at the top, at ca 92 m a.s.1. the uppermost 2-3 m are cobbles and boulders which can be followed or the surface above the hidalen ravine to the coarse-grained high-energy beach ridges that mark the marine limit at ca 100 m a.s.1. in the mouth of hidalen. it is interpreted to be a succession of sublittoral t o littoral sediments. deposited when the sea stood at the postglacial marine limit. the glacial stratigraphy of bogen section 25-01 (fig. 6) is located about 1.5 km from the coast. in a shallow side ravine to the main bogen gully (fig. 1c). inside the bogen cirque. the top of the section is at 82 m a.s.1. the cirque mouth is transversed by a 94-08 m high boulder ridge. marking the marine limit. the section is composed of two interstratified lithofacies. laminated sand and laminated silt. with minor intrabeds of massive sand and massive silt. t h e thickness of the strata as exposed at site 23-01 is about 7 m . t h e clayey-sandy sediments carry in situ shells and abundant shell fragments. the deposition has been continuous. with mod erate sediment input, and minor current rework ing during deposition. probably in a shallow water. low-energ), marine environment. drop stones occur, mainly as occasional granules and pebbles. t h e section is capped by thin colluvium. the whole section has been glaciotectonically deformed, and pushed up-slope from the floor of the bogen valley. in the northern part of the section (left on fig. 6 ) . a gently inclined, tight anticlinal fold has developed, and in the southern part of the section the sequence is transected by series of tightly spaced low angle reverse faults. the fold axis has a se-nw direction, and the deforming thrust has come from the northeast. the tightly spaced low angle reverse faults have an imbricated pattern, slightly concave with apparent dip towards the north. t h e faulting has occurred subsequent t o the folding in a ne-sw orientated stress field. t h e direction of gla ciotectonic deformations in section 23-oi shows that t h e glacier which overran the site had advanced across t h e 300 m high retziusfjellet pla teau, into the cirque. thus the glacier has been a part of a larger ice sheet covering kongsarya and probably this part of the barents sea. molhscs. only four species of bivalves and o n e echinoderm were recognised (table 1). t h e shells were biased towards large individuals, and no juveniles were recognised. this, together with the total absence of foraminifera, indicates that carbonates may have dissolved in the sediments. plant macrofossils. only o n e taxon of vascular plants. selaginella selaginoides, was recognised. together with fragments of leaves, stems and wood (table 3 ) . t h e bryophyte assemblage is similar t o t h e flora in unit b in hidalen, with well fig. 6 . site 13-01 in bogen. north to the left of the photo. the anticlinal fold shows a glacial push from northeast and that the sediments have been pushed up-slope from the floor of the bogen cirque. late quaternary glacial and enuironmental history of kongsgya, soalbard 135 represented wetland species. this assemblage has more species indicative of drier habitats than unit b in hidalen. but taken together the flora shows poor vegetation of vascular plants and bryophytes in mineral-poor, leached out soils. the presence of selaginella selaginoides suggests that the cli mate was slightly warmer on kongscdya during the deposition of these sediments than today. age and correlations radiocarbon and t l ages four 14c age determinations were made on samples from units b and d in hidalen and the bogen strata. all gave infinite ages (table 4). one tl dating from the bogen strata yielded an age of 148 5 15 ka. amino acid ratios the degree of isoleucine epimerization. expressed as aile/ile ratios, were measured in 21 samples from five different sites in hidalen and from the bogen site. the samples were prepared b y the method described by (miller et al. 1983) and the aile/ile ratios in the total (bound + free) and free fraction are presented in table 5 . most of the shells were of the species hiatella arctica and table 4 . radiocarbon dated pelecypod samples from western kongs0ya. site sample no. lab. no. age bp hc-13 ( % ) ~ hidalen 15-30c 95-405 lu-3823 >38.000 -1.9 hidalen 15-31 95-438 lu-3821 > 40,000 2.5 hidalen 14-03 95-439 lu-3822 > 40 .000 3.1 bogen 23-01 95-440 lu-3824 >37.000 3.2 all samples are of in situ mya truncata except sample 95-439 from site 14-03 where a reworked. paired specimen of chla~nys islandica was dated. table 5. amino acid aile/ile ratios from western k o n g s ~ y a . svalbard ~ site bal unit number 15-30c 15-31 14-03 15-30a 15-30b 1530a 23-01 d 2529 d 2612 d 2613 d 3073 d 2575 d 2610 d 261 1 d 3074 d 3072 e 2693 e 2694 e 2695 b 2530 b 2531 b 2574 e 2528 2524 2525 2527 2576 species mya truncata hiatella arctica mva truncata mya truncata hiatella arctica hiatella arctica hiatella arcricu mya truncata mya truncata hiatella sp. hiatella sp. hiatella sp. mean: mya truncara hiatella arctica mya sp. hiatella sp. mva truncata mva truncata mya truncata mya cruncata mean: hydrolysed aile/ile ratio 0.039 ? 0.006 0.049 f 0.001 0.050 f 0.004 0.029 i 0.004 0.056 i 0.005 0.035 f 0.000 0.044 t 0.001 0.034 t 0.001 0.043 t0.003 0.046 2 0.000 0.054 f 0.001 0.046 * 0.001 0.043 t0.008 0.085 f 0.008 0.074 f 0.006 0.080 ? 0.003 0.071 f 0.016 0.095 ? 0.002 0.085 ? 0.002 0.095 t 0.002 0.082 f 0.005 0.083 * 0.009 free aile/ile ratio 0.243 ? 0.072 0.233 f 0.009 0.199 t 0.014 0.229 f 0.028 0.207 f 0.069 0.192 t 0.019 0.188 f 0.015 0.194 t 0.006 0.241 2 0.016 0.258 ? 0.013 0.290 t 0.020 0.231 f 0.038 0.372 ? 0.025 0.425 f 0.008 0.354 f 0.001 0.301 t0.086 0.303 f 0.022 0.433 ? 0.016 0.401 f 0.016 0.381 t 0.003 0.373 ? 0.013 0.380 * 0.042 comments from scree from scree from scree in situ from scrcc from scree from scree in situ not in situ fragment fragment fragment not in situ not in situ fragment fragment in situ in situ in situ in situ the bal-number is the sample number at the bergen amino acid laboratory. 136 c 0 0 . e !? p 5 e q, e 0, c in 0 . . e e q, q, m . 0 mya truncata hiatella arctica fig. 7. amino acid aile/ile 0,02 0,04 0,06 0 , o a 0 , l o 0 , 1 2 ratios in all measured allellle ratios in the hydrolysed fraction samplcs from weatcm kongsdya. m y a triiiicata, but some fragments could not be identified. o n the basis of amino acid ratios (method described by a n d r e w et al. 1985) they were identified as hiatella sp. and my" sp. the sample material falls into two groups of different age (fig. 7 ) . the older group. with an average of 0.083 i 0.00y in the hydrolysed fraction for 8 samples, of shells from unit b in section 15-30b in hidalen and from section 23-01 in bogen. as well as a fragment from unit e in section 15 30a. the younger group. with an average of 0.043 5 0.009 for the hydrolysed fraction for 12 samples. consists of shells from unit d at sites 15 3oc. 15-.71 and 14-03. together with fragments sampled from unit e in section 15-30a. t h e relatively large variations in ratios within the groups might reflect different temperature history as a result of burial depth as some of the samples were found i n scree material at or close to the surface. s i x samples. coming from unit d but collected from surface scree. yielded an average ratio of 0.045 5 0.007 for the hydrolysed fraction and 0.234 5 0.038 for the free fraction. two samples collected in situ from the same deposit. near the base of the active layer at 0.1 0.6 m in the sediments, yielded an average ratio of 0.031 i0.003 for the hydrolysed fraction and i ) . 1y3 _t 0.007 for the free fraction. we consider the mean aile/ile ratio from in situ shells as more reliable than the total mean for the younger group. the amino acid ratios confirm the strati graphical evidence of two ice-free intervals, dur ing deposition of units b and d. in hidalen. t h e amino acid ratios suggests that the marine beds in bogen correlate with unit b in hidalen. correlating the kongsgya stratigraphy to spitsbergen correlations between different sites on spits bergen is difficult because of lack of reliable absol ute dating methods. therefore such correlations of possible early weichselian and eemian sites have relied heavily on amino acid ratios (miller et al. 1989; sejrup bt larsen 1991, mangerud bt svendsen 1992; landvik et al. 1992). even if other factors than diagenetic temperature may influence on the o n the degree of epimerisation, the temperature is the most crucial (sejrup bt haugen 1994). therefore, in order to use the amino acid ratios for regional stratigraphic cor relations and establishing relative chronologies, the temperature history has to be comparable from site t o site (sejrup 1990). as demonstrated with the data from kongssya, burial depth during ice-free conditions can seriously affect the aile/ ile ratios o n samples of same age. a composite stratigraphical scheme for kongs oya is shown in fig. 8. t h e t l determination from bogen indicates that the older ice free interval o n kongscdva is older than isotope stage 5e. t h e late quaternary glacial and environmental history of kongsgya, svalbard 137 i -ocal composite unit ! lithological log c b shells i 1 shells depositional event sublittoral deposition subglacial deposition t > 4 0 000 littoral deposition c .r p m~ a : >38 000 shallow-marine deposition >40 000 subglacial deposition littoral deposition sublittoral deposition 148klc shallow-marine deposition subglacial deposition mean allellle ratios 0.031 i0 003 0.083 io.009 voposed :hronostratigraphy holocene late weichselian early weichselian or eemian pre-eemian fig. 8. composite stratigraphy of western kongsbya. unit thicknesses are arhitrary. lithological legend in fig. 7 table 6. amino acid ratios in pelecypod shells from sites on spitsbergen. for comparison. the amino acid values from kongsaya and their proposed age. isotope stage chronostratigraphy br~ggerhalvbya kapp ekholm linntdalen skilvika kongsaya 1 holocene 0.01s t 0.003 2 late weichselian 3 middle weichselian 0.026 k 0.004 0.019 t 0.003 4 sa early weichselian 0.031 2 0.003 0.027 ? 0.003 0.031 t 0.003 5h s c 0.0h3 ? 0.013 0.037 t 0.00x sd se eemian 0.044 * 0.004 0.069 t 0.008 pre-eemian 0.121 t 0.009 1).083 i0.009 based on miller et al. (198y), mangerud & svendsen (1992). lenne & mangerud (1991) and landvik et a l . (1992) mean amino acid ratios are considerably higher than those obtained from assumed eemian austlandet (blake 1989). deposits on spitsbergen (table 6). and we suggest that unit b pre-dates isotope stage 5e. amino acid ratios in the same range as the older group on kongsoya have been reported from nord if the glacier advance which deposited unit e , the uppermost till, correlates with a late weich selian barents ice sheet, the younger ice free interval. unit d. could possibly correlate with the kapp ekholm interstadial. mangerud & svend sen (1y97) assign i t the age of 1o.ooo-~o.ooo bp and argue that then the whole barents sea area was ice free. the aile/'ile ratios obtained from i n situ shells from unit d on kongssya are slightly higher than mean ratios from the kapp ekholm interstadial deposits. since the kongssya samples come froni altitudes of between ca 55 and 75 m a.s.1.. as compared to 4 5 m a.s.1. for the kapp ekholm samples. and the annual mean tem perature is lower on kongssya than at kapp ekholm. one would expect that similar aile/lle ratios v.ould indicate higher age for the kongssya deposit\. we suggest that unit d sediments are either o f early weichselian or eemian age. if our correlations are correct. our data support the conclusion of sejrup 6r larsen (1991) that a hio stratigraphical distinction between interglacial and interstadial ciepo5its at such high latitudes may be difficult. summary and conclusions the stratigraphic data from kongssya show three coarsening-upwards successions of marine to lit toral sediments. separated by tills. these show at least three late quaternary major glaciations of the northern barents sea. with ice thick enough to cause substantial glacioisostatic downpressing of western k o n g s ~ y a . t h e high (2100 m) post glacial marine limit. dated to around 11).000 bp. suggests that this part of the barents sea was covered by a n ice sheet during the late weich selian. and the uppermost till in the kongssya stratigraphy is related to that glacial event. glaciotectonic deformations suggest that ice at some time moved independently of the local topography from an ice-divide northeast of kong s0ya. the stratigraphical evidence shows two pre holocene ice-free periods. where the climate was similar to or slightly warmer than at present. the a_ge of these ice free intervals is not clear. we suggest that the older ice free period predates isotope stage 5e. t h e younger ice free period could either be of eemian or early weichselian age. -ickriu\s itdgernerirs. we are grateful to the sorwegian auth uritier for d l o n i n g u s to d o fieldwork in kongsaya within the northed\f svalbard nature reserve. as well as for logistic supporl. the nor\\sgian polar institute supported us in various ways. a . hansen looked for foraminifera in some of our older sample5 s . funder analysed the mollusc species. 1. karnefelt and r . danielsson provided information on the present fauna and flora of kongsova. the swedish natural sciencc research council financed the re5earch of 0. ing6lfsson. and has given generous grants for this project. the participation of f. kognvaldsson and h . p . sejrup was made possiblc by contributions from the research council of norway, norsl hydro, saga. statoil and the norwegian petroleum directorate. the polar research secretariat ol sweden gave various logistics support. the department of quaternary geology. lund univcrsity. pro vided funds to pay for two of the " c dates. helicopter transport waq financed through a grant from the european commission to ihc european science foundation. the paper bencfitcd from comments made by w. blake. s . funder and s . forman. this is a contribution to thc european science foundation project: polar north atlantic margins. late cenozoic evolution ( p o n x h l l references andrews. j . t.. miller. g . h . , davies. d. c. & d;ivie\. k . h 1985: gcneric identification of fragmentary quatcrnary molluxs by amino acid chromatography: a tool for quat crnar) and paleuntological research. grol. j . 2 0 . i-2(1 blahe. w . 1989: radiocarbon dating by accelerator mdsa spec tometr): a confribution to the chronology of holocene cbcnts in nordaustlandet, svalhard. georgr. ann. 71a, 59-74. boulton. g . s 197'): glacial history of the spitsbergcn archi pelago and the problem of a barents shelf ice sheet. boreus s. 31-57, de geer. g . 1900: om dstra spitshcrgens glaciation under iatiden. geol. foreri. srockholm forharid. 22, 427-136 eherhoi. a . 6: solheim. a . 1983: the barents sea ice sheet a sedimentdogical discussion. polar lies. i , 23-42. el\erhoi. a , . nyland-berg. m . russwurm. l . rr solheim, a . 19w: late weichselian ice recession i central barents sea. pp. 29g-307 in bleil. u . & thiede. j . (eds.): geological hisrorv of the p o l a r ocean.^. kluwer academic publishers. dordrecht. e h r r h o i . a,. fjeldskaar. w.. solheim, a . . nyland-berg. m . 6: russwmrm. l. 1993: the barents sea ice sheet a model of its growth and decay during the last ice maximum quar. s1-r. reo. 1-7. 86.%874. feyling-hansaen, r . w. & ulleberg. k . 1984: a tertiary quatcrnar) section at sarsbukta. spitsbergen. svalhard and its toraminitera p o l a r re.s. 2. 77-106. fitter. k . & manuel. r . 1986: field g u i d e to rhe freshwater [.iff of britarri and n o r t h w e s t europe. collins. london. 382 pp forman. s . l . 1990: pix-glacial relative sea-level history of north-western spitsbergen, svalbard. geol. soc. ofam. bull. 1 i).? , 15801sw. forman. s l . . lubinski. d , miller. h .snyder. i . . matishov. g . korsun. s . & myslivets. v . 1995: postglacial cmrrgence and distribution of late weichselian ice-sheet loads in the northern barents and kara seas. russia. geol. 2 3 . 113-116. hansen. a . & knudsen. k. l. 1992: recent foraminifera i n freemansundet. eastern svalbard i i i moller. p.. lljort. c . 6: ingolfsson. 0. (eds.). lundqua report 35. 177-179. harde. r. w. 1984: a field guidein colourro beetles. octopus b o o k a . london. 334 pp. hedenas. l. 1989: the genus sanionia (musci) in northwrstern europe. a taxonomic revision. ann. bor. f m n i c i 20. 399 419. late quaternury glacial and environmental history of k o n g s ~ y a , svulbard 139 hedenas. l. 1992: a subfossil find of pseirdoculliergon bre uifoliimm in northern sweden. liridbergia 16, 150-152. hedenas. l. 1994: a subfossil occurrence of loeskvpnum wickesii in northern sweden. liridbergia 18, 131-134. hoppe, g . 1972: ice sheets around the norwegian sea during the wiirm glaciation. amblo spec. rep. 2: 25-29. hultkn, e.. &fries, m . 1986: atlas of norih european vascular plants. vol 1-111. koeltz scientific books, konigstein. 1172 pp . ingolfsson, 0.. rognvaldsson, f. & sejrup, h. p. 1992: the glacial history of western kongseya. svalbard. in moller, p . , hjort, c. & ingolfsson. 0. (eds.), lundqua rep. 35,25-49. ingolfsson, 0. & lirio. j . m. 1993: the glacial geology of kongseya revisited. pp. 6 1 1 in landvik, j. (ed.): p o n a m fieldwork in sualbard 1yy3. preliminary report. knape, p. 1971; c-14 dateringar av hojda strandlinjer, synkrona pimpstensnivser och iaktagelser av hogsta kustlinjen p i sval bard. unpublished lic. dissertation, s t o c k h o l m uniuersiiei, naturgeografiska institutionen: 142 pp. lambeck, k . 1995: constraints on the late weichselian ice sheet over the barents sea from observations of raised shore lines. qirar. sci. reu. 14, 1-16. landvik, j . y . , bolstad, m . . lycke, a. c., mangerud, j . & sejrup, h . p. 1992: weichselian stratigraphy and palaeo cnvironment at bellsund. western svalbard. boreas 21, 335 358. long, d. g. 1992: sanionia orthoihecioides (lindb.) loeske in scotland, new to the british isles. 1. bryol. 17. 111-117. long, d. g. 1993: sanionia orthothecioides on the scottish mainland. j . bryol. 17, 513514. lycke, a . k., mangerud, j . & sejrup. h. p. 1992: late quat ernary foraminifera1 stratigraphy from western svalbard. boreas 21, 271-288. lenne, i . rr mangerud, j. 1991: an early or middle weich sclian sequence of proglacial. shallow-marine sediments on western svalbard. boreas 20. 85-104. mangerud, j . & svendsen. j . i . 1992: the last interglacial glacial period on spitsbergen. svalbard. quar. sci. reu. 11, 633-664. mangerud, j . , bolstad, m.. elgersma. a , . helliksen, d.. land vik. j . y . , l m n e , i . , lycke, a . k . salvigsen, 0.. sandahl. t. & svendsen, j . i . 1992: the last glacial maximum on spitsbergen. svalbard. quai. res. 38, 1-31. millcr. n. g . 1987: late quaternary fossil moss floras of eastern north america: evidence of major floristic changes during the late pleistocene-early holocene transition. symp. biol. hungarica 3s, 34s360. miller, g. l i . , sejrup. h. p., mangerud, j. & andersen. b.. g. 1983: amino acid ratios in quaternary molluscs and foraminifera from western norway: correlation, geochron ology and palentemperature estimates. boreas 12, 107-124. miller, g . h . , sejrup. h . p . . lehman. s. j. & forman, s . l. 1989: glacial history and marine environmental change dur ing the last interglacial-glacial cycle, western spitsbergen. boreas 18, 273-296. mossberg, b . , stenberg, l & ericsson. s . 1992: den nordiskcr floran. wahlstriim & widstrand, stockholm. 696 pp. nagy. j. 1984: quaternary glaciomarine deposits and fora minifera from edgeoya. svalbard. boreas 13, 319-332. nathorst. a . g . 1901: bidrag till kong karls lands geologi. geol. f o r m . stockholm forhand. 23, 341-378. pike, a . 1898. a cruise on the east of spitsbergen. georgr. j . i , 365-371. polyak, l. & solheim. a. 1994: lateand postglacial environ ments in the northern barents sea. west of franz joscf land. polar res. 13. 197-207. rognvaldsson. f. 1992: a m i n o acid geochronology and pala eorhermometrv of quaternary sedimenrs on jameson lund, east greenland and kongsmya. sualbard. unpublished cand. scient. thesis, department of geology. university of bergen. norway. 89 pp. renning, 0. 1. 1979: sualbards flora. polarhindbok nr. 1 . norsk polarinstitutt, oslo. 128 pp. salvigsen, 0. 1981: radiocarbon dated raised beaches in kong karls land, svalbard. and their consequences for the glacial history of the barents sea. geogr. ann. 63a: 2kl291. salvigsen. 0. rr nydal. r. 1981: the weichselian glaciatmn in svalbard before 15.000 b.p boreas 10. 433-446. schytt. v., hoppe, g . , blake, w . . j r . & grosswald. m. g . 1968: the extent of the wiirm glaciation in the european arctic. lnternaiional association of scientific hydrologv. gerr era1 assemblv of bern 1967. publicailon 79, 207-216. sejrup. h. p. 1990: amino acid geochronology. i n medd. grgnl. geosci. 22, 36-39. sejrup, h . p. & larsen. e. 1991: eemian-early weichselian n-s temperature gradients; north atlantic nw europe. quar. lnr. 10-12. 161-166. sejrup, h . p. & haugen. j . e . 1994: amino acid diagenesis in the marine bivalve arctica islandica l i m e from nv-euro pean sites: only time and temperature? j . quar. sci. 9. 301 310. siegert, m. j. & dowdeswell, j . a . 1995: numerical modelling of the late weichselian svalbard-barents sea ice sheet. @at. res 43, 1-13. smith, d . g . , harland, w . b. hughes. n. f. & picton. c. 1976: the geology of kong karls land. svalbard. geol. mag. 113: 193-232. solheim, a.. russwurm, l.. elverhei, a . & nyland-berg. m . 1990: glacial geomorphic features i n the northern barenth sea: direct evidence for grounded ice and implication, f o r the pattern of deglaciation and late glacial sedimentation. pp. 253268 in dowdeswell. j. a. & scourse. j . d. (eds.): glacimaritie enuironments: p r o c e u a and sedirneriia, grol. soc. london. spec. publ. 53. stromberg. b. 1972: glacial striae in southern hinlopcnstrcdct and kong karls land. svalbard. geogr. a n n . 54a soderstrom, l., hedenas. l. & hallingback, t . 1992. chcck lista over sveriges mossor. myrinia 2. 13-56, vorren, t . 0.. hald, m. & lebesbye e . 1988: late cenozoic environments in the barents sea. paleocenogr. 3 , 601-612. an arctic expedition: a supposedly useful thing i’ll never do again perspective an arctic expedition: a supposedly useful thing i’ll never do again maud a.j. van soest uk centre for ecology and hydrology, environment centre wales, bangor, uk abstract the aim of the second scientific expedition edgeøya spitsbergen (sees), which took place from 13 to 22 july 2022, was to study the consequences of climate warming in the high arctic, building on ecological data gathered by the dutch arctic station on edgeøya between 1968 and 1987 and the first sees expedition in 2015. in this perspective essay, i ponder the actual purpose of sees 2022, in which i participated as an early-career research scientist. the research activities were very limited and climate change was named as the restricting factor. fifty researchers were accompanied by 50 tourists, journalists and policymakers. the choice made by the expedition leaders and funders to go for a tourist vessel was mostly financial, and the difference in media output versus expected research output substantial, which points to paradoxes related to research, publicity, politics and tourism in the arctic. keywords climate change awareness; fieldwork, tourism; geopolitics; research funding abbreviation sees: scientific expedition edgeøya spitsbergen (netherlands)   citation: polar research 2023, 42, 9070, http://dx.doi.org/10.33265/polar.v42.9070 copyright: polar research 2023. © 2023 m.a.j. van soest. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 05 june 2023 competing interests and funding: the author declares no conflict of interest. this article is the result of my participation in sees in 2022, which was partly funded by the dutch research council and the dutch arctic centre of the university of groningen. a full list of funders can be found on the website sees.nl/2022. the uk centre for ecology and hydrology ukceh funded my travel to svalbard and project time. this publication is financially supported by the organizers of the sees.nl expedition at the arctic centre of the university of groningen. correspondence: maud a.j. van soest, uk centre for ecology and hydrology, environment centre wales, deiniol road, bangor, gwynedd, ll57 2uw, uk. e-mail: mausoe@ceh.ac.uk   introduction the arctic is warming four times as fast as the global average (rantanen et al. 2022). combined with technological improvements, this is making the arctic more accessible (stephen 2018). as a result, interest in the region has grown, particularly within non-arctic nations (smits et al. 2017) in terms of politics, research activity and tourism (saville 2019), and attention in popular media (stephen 2018). drawing from my personal experience as a scientist aboard a research expedition to svalbard, i describe how these different actors come together, sometimes harmoniously and occasionally with friction. the second sees had been postponed twice because of the covid-19 pandemic and it was not until july 2022 that i finally boarded the ortelius in longyearbyen. since first signing up for the expedition, i had finished my phd and changed institution and was lucky to still be able to participate. the scientific aim of the expedition was to study the consequences of climate warming in the high arctic, building on ecological data gathered around a dutch arctic station on edgeøya, svalbard, between 1968 and 1987 and the first sees expedition, in 2015. fifty participating researchers were accompanied by 50 tourists, journalists and policymakers. the tourists, also referred to as science supporters or science ambassadors, had paid a minimum of 7000 eur to be part of the expedition. their journey was advertised as “the arctic academy,” a collaboration between sees, the cruise company oceanwide expeditions and the travel company snp natuurreizen that encouraged science supporters to partake in the collection of valuable data (oceanwide expeditions 2022). as science ambassadors, they would contribute towards raising public and political awareness for the expedition, the need for arctic research and the consequences of climate change (university of groningen 2022a). the combination of scientists and tourists was considered a promising experimental setting for citizen science projects (university of groningen 2022b). after nine days at sea, the expedition ended with a seminar day at the university centre in svalbard, where the first findings were shared with other scientists, students and the public. the netherland’s ambassador in norway and the arctic ambassador of the netherlands were special guests. the expedition sea ice retreated much further north around svalbard during the summer of 2022 compared with 2015 (nasa earth observatory 2022; norwegian meteorological institute 2022). this apparently contributed to worse swells, which made it unsafe for expedition participants to reach the shore in zodiacs (sees.nl). it also left many polar bears behind on the islands (sees.nl 2022; see also blanchet et al. 2020; stempniewicz et al. 2021). it was also very foggy at times because of higher temperatures and humidity, which made it dangerous to go on land as polar bears could not be spotted. ironically, as we experienced the consequences of the climate warming that we were supposed to be investigating, no one was able to go on land during the first three days of the expedition and research activities were restricted throughout the rest of the expedition as well. having to stay on board the ship was a mental challenge for many participants, not least the researchers whose much-needed time on land for their data collection was sharply curtailed. because of the environmental conditions and the limited number of guides and rifle-carriers, only a small group of scientists would go ashore where a landing was possible, which cut back on the opportunities for the non-scientist participants to collaborate with the scientists. although some projects were not land-based and were therefore less hindered, the pressure on the expedition leaders increased to meet the overall aims and keep everyone happy. knowledge was still being shared in the form of lectures, and zodiac cruises were organized to bring participants closer to glaciers or shore, while maintaining a distance for our safety and to limit the disturbance to wildlife. hence, pictures of polar bears remained pixelated. an exception was made for the camera crew of the netherlands national news and their shots were later sold to the press to illustrate stories about the expedition. most dutch newspapers featured the expedition and articles came out in popular science magazines as well. several engaging items combined still pictures, videos, well-designed graphs and quotations. ninety items were published by october, only a few months after the expedition. this had the benefit of helping people understand why scientists are devoted to working in such a difficult and vulnerable environment as the arctic. in contrast to the large popular media output, only one peer-reviewed paper has been published so far, seven years after the sees in 2015. being less limited by natural forces, the first expedition was considered a success in terms of deepening our knowledge of svalbard’s ecology. time will tell how many more published scientific articles will stem from the sees 2015, 2022 or a combination of both. the slim research output—as measured by publications—compared with the roaring media stories made me wonder what the main purpose of the expedition was. the choice of the expedition leaders and funders to go for a tourist vessel was mostly financial since (arctic) research is expensive. for the amount it cost for nine days on the tourist vessel ortelius, the polarstern, a german research vessel, could not be rented for even three days. a storage facility and laboratory were constructed on deck so that equipment and samples could be kept on board for the duration of the tourist season, which lasted until september, when the ship sailed to the netherlands. this reduced the financial and environmental cost of transporting the samples and research gear back to continental europe. moreover, the cheaper option of a tourist ship freed up funds for a group of 50 scientists to participate, including several early-career researchers with very small budgets. sees was a floating conference and it provided opportunities for networking, which is valuable for young researchers’ careers. there was ample time for informal discussions, presentations, meetings and friendly conversations. probably even more important were the long-lasting personal bonds formed through shared experience. the arctic traveller the relatively untouched arctic is often referred to as a natural laboratory (e.g., powell 2007; finger 2016). its environments contain valuable information that can be examined through multiple temporal and spatial scales and are worthwhile studying across scientific disciplines. not all research questions can be answered with remote sensing techniques, which is one justification for travelling to vulnerable regions for scientific purposes. however, in remote areas, the environmental impact of research might be the single most important direct anthropogenic influence and should therefore be minimized by making the right choices in relation to logistics and science activities (frendrup et al. 2021). unforeseen circumstances threw off the balance between science and luxury during the sees, leaving me and others with an uncomfortable feeling of guilt. someone framed the expedition as “an expedition for researchers whose travel was funded by taxpayers” and, at the same time, “a cruise for tourists paying for hotel service.” i wasn’t sure whether i identified most with the tourists or the researchers in this characterization. each generous meal was catered to every taste. i can only hope that some of the leftovers went into the next day’s soup. with a shower and toilet in every cabin, and staff continuously cleaning the ship, the quantity of wastewater produced must have been considerable. it was cringe-inducing to think about the pollution and waste created by an expedition that had the theme of sustainability and climate change. there is an emotional component attached to the opportunity to do fieldwork and travelling for work can add value to daily life (duveau 2021). while often treated differently in terms of access to, and the right to be in, (parts of) svalbard, scientists and tourists are likely to be attracted to the area by similar motivations, both groups seeking to learn more about the features of svalbard that interest them (saville 2019). the sees scientist participants were given blue expedition jackets, easily identifiable and distinguished from the tourists, who did not have such jackets (fig. 1). moreover, the tourists were not allowed to go ashore without a guide from the tourist company, whereas at least a few scientists had more freedom to roam around as long as they carried, and knew how to use, a rifle. but, overall, scientists and tourists visited the same places, took part in zodiac excursions, and mingled in the ship’s dining room and bar. fig. 1 the author collects soil samples in rosenbergdalen, on the island of edgøya, svalbard, on one of the occasions that she was able to do fieldwork during the 2022 sees expedition. (photo: dagmara wojtanowicz.) adventure tourism and luxury cruises are both on the rise (kerber 2022). ‘last chance tourism’ arises from the wish to see vulnerable features and places, like the arctic, before they disappear or change irreversibly, even though—paradoxically—travelling further alters the attractions being visited (dawson et al. 2011). eijgelaar et al. (2010) found that daily per capita greenhouse gas emissions by cruise ship tourists can be as much as eightfold that of the average international tourist. there is no evidence that the so-called ‘ambassadors’ for conservation who populated these cruise ship tours developed greater environmental awareness, changed attitudes or encouraged more sustainable travel choices after their cruise (eijgelaar et al. 2010). kerber (2022) provided an interesting examination of polar cruise promotion and reveals the discord between the visitors’ hopes and the cultural geophysical realities in a changing environment. i experienced first-hand how the arctic traveller expects, and is expected, to come home with engaging stories and dazzling pictures of a white landscape. the disappointment was striking when some tourists on the sees expedition realized that only about half of svalbard is ice-covered in the summer and the sea ice had withdrawn to the north of the archipelago. the need to fulfil the expectations of the paying customer could drive tourism operators further towards the north pole, which could put both the environment and the tourism industry at risk. storytelling and the value of publicity starving polar bears have become emblematic of a changing arctic, although population numbers tell a different story (aars et al. 2017). the abundance of polar bears on land was framed by the expedition leaders as a consequence of climate change, in line with the research aim of the expedition. however, the good news that the svalbard’s polar bear population appears to be stable, and may even still be rebounding following the 1973 ban on hunting (aars et al. 2017), was barely mentioned. the regulations that protect polar bears from human disturbance in svalbard (hovelsrud et al. 2021) impacted the expedition but were not mentioned, and i assume this was because they sounded less urgent and less interesting than climate change. the expedition was partly justified by the science knowledge that was going to be passed on to the general public and the awareness of environmental issues that this would raise. however, the scientific findings, as conveyed by the media, were sometimes distorted and oversimplified. one sees researcher, who studies creatures that are thriving in a warmer climate, observed that a journalist had twisted this participant’s words to make them less incongruous with the overall message of climate doom and gloom. storytelling is extremely important to inform and engage the public. scientists are motivated to participate in public communication partly by a desire to improve public engagement and understanding (horst 2013). public visibility also helps attract funding. as securing resources becomes more competitive and the focus on hot topics that engage the public and the commercialization of research increases, publicity can be seen as branding to attract funding for future projects (horst 2013). the value of publicity was recognized by the early-day polar explorers who invited photographers on their journeys. upon their return, the explorers were received as heroes and there was great interest in their stories of the polar regions (lewis-jones 2017). a portfolio of pictures boosted visibility, influence and, ultimately, profits. the three most famous examples—robert falcon scott, roald amundsen and ernest shackleton—were businessmen who travelled thousands of miles more to sell their stories compared with the distance of their polar explorations. scott was driven by science (larson 2011), and the expeditions of all three men resulted in the collection of important scientific data (barnes et al. 2011; harrowfield 2014; blix 2016). contracted by publishers and brands to deliver or promote exclusive products, the men used the money to fund later expeditions, as well as to maintain their fame and luxurious lifestyles. the polar explorers active during the heroic 19th and early 20th century contributed to longstanding national histories and heritages in the arctic and antarctic, initiating current-day geopolitical positioning in these regions (elzinga 2012). science and politics longyearbyen, the largest settlement in svalbard and its administrative centre, was crowded with people in those blue jackets prior to and after the sees expedition. the jackets were emblazoned with funders’ logos and the dutch national flag. the netherlands is one of the few countries that keep referring to svalbard as spitsbergen, which means pointy mountains and is the name given to the archipelago by early dutch explorers, even though this is currently the name of the main island only. these forms of national posturing are common practice in svalbard (pedersen 2021). here, visibility is political impact. political science and popular science publications about the arctic are on the rise (stephen 2018). pedersen (2021) argues that the surge in polar research may be partly explained by nations seeking a strategic presence in polar regions as they position themselves to adopt new transport routes, explore more easily accessed offshore resources or take advantage of other new opportunities arising from climate change and technological developments: science raises the least public display of distrust compared with other politically motivated actions. in the context of antarctica, convey (2023) suggests that science may be a way to demonstrate national presence while also generating scientific knowledge. for the modern research community, international collaboration and open access to knowledge and data are key, not least with regard to arctic and climate research (iasc 2022). the politicization of knowledge and the geopolitical aims that influence national science programmes are likely to lead to certain scientific fields being prioritized over others and the failure to fund good research that is not linked, for example, to climate change (chubb & reed 2018; convey 2023). (geo)politics influence science via funding allocation and scientific impact increases the geopolitical position of a country as an arctic stakeholder (stephen 2018). research in the remote arctic regions is expensive because of the logistics and limited facilities. mallory et al. (2018) showed that similar research activities can be eight times more expensive in the arctic compared with more easily accessed locations. funding many small projects may have the advantage of making the research flexible and adaptable within short spans of time, whereas funding few large-scale, long-term projects may promote international collaboration and sustainability (ibarguchi et al. 2018). sees brought together a big group of people and generated lots of visibility, but it might not have been the most efficient vehicle for gathering environmental data. a smaller, targeted expedition would likely have been more flexible and successful in terms of data collection. for example, even with the safety considerations mentioned earlier, more of the scientific personnel of a small expedition would have been able to go ashore and work on land, collecting the data they set out to collect, unrestricted by the working hours of the tourist staff. on the other hand, a small expedition would not have had the same media impact (and possibly, as a result, political impact) as a larger, mixed expedition like sees. conclusion as argued by saville (2019) and duveau (2021), scientists are just humans and they are drawn to the arctic for a variety of reasons. i noticed during the expedition that many participants were trying to justify their presence in this vulnerable landscape in terms of contributing to research, while also allowing themselves occasionally to be amazed by what they experienced. the imbalance between science and luxury, between research output and media attention, made me wonder if the stated aims of the expedition were met. it also made me question the role of the researcher—and science as an institution—within the wider society. drawing from my personal experience, this article touches on such issues as the politics of knowledge, the commercialization of science, how science is reported in the media, and the relationship between science and tourism. these topics were not discussed in a formal setting during the sees expedition and were only voiced during private conversations among the participants. i believe that there is a need for an open debate, across the relevant disciplines, institutions and industries, to allow for the sustainable continuation of research and tourism in vulnerable areas. for me, sees was useful in terms of building my cv, being introduced to a great professional and social network and, ultimately, giving me the opportunity to visit and study the exceptional environment of svalbard. but i will never travel to the arctic in similar circumstances again. acknowledgements i am grateful to adwin de kluyver for his valuable support and thoughts on the manuscript. i would also like to thank the reviewers for their positive feedback and everyone i met during the sees expedition, for taking me onboard and for their hospitality, company and interesting conversations. references aars j., marques t.a., lone k., andersen m., wiig ø., bardalen fløystad i.m., hagen s.b. & buckland s.t. 2017. the number and distribution of polar bears in the western barents sea. polar research 36, article no. 1374125, doi: 10.1080/17518369.2017.1374125. barnes d.k.a., kuklinski p., jackson j.a., keel g.w., morley s.a. & winston j.e. 2011. scott’s collections help reveal accelerating marine life growth in antarctica. current biology 21, article no. r147–r148, doi: 10.1016/j.cub.2011.01.033. blanchet m.-a., aars j., andersen m. & routti h. 2020. space-use strategy affects energy requirements in barents sea polar bears. marine ecology progress series 639, 1–19, doi: 10.3354/meps132290. blix a.s. 2016. on roald amundsen’s scientific achievements. polar research 35, article no. 31319, doi: 10.3402/polar.v35.31319. chubb j. & reed m.s. 2018. the politics of research impact: academic perceptions of the implications for research funding, motivation and quality. british politics 13, 295–311, doi: 10.1057/s41293-018-0077-9. convey p. 2023. what is the place of science in antarctica? antarctic science 35, 1–3, doi: 10.1017/s095410202300007x. dawson j., johnston m.j., stewart e.j., lemieux c.j., lemelin r.h., maher p.t. & grimwood b.s.r. 2011. ethical considerations of last chance tourism. journal of ecotourism 10, 250–265, doi: 10.1080/14724049.2011.617449. duveau s. 2021. frozen data? polar research and fieldwork in a pandemic era. polar record 57, article no. e34, doi: 10.1017/s0032247421000541. eijgelaar e., thaper c. & peeters p. 2010. antarctic cruise tourism: the paradoxes of ambassadorship, “last change tourism” and greenhouse gas emissions. journal of sustainable tourism 18, 337–354, doi: 10.1080/09669581003653534. elzinga a. 2012. changing trends in remembering amundsen and scott. journal of northern studies 6, 113–122. finger m. 2016. the arctic, laboratory of the anthropocence. in l. heininen (ed.): future security of the global arctic: state policy, economic security and climate. pp. 121–137. london: palgrave pivot. frendrup l.l., rasch m., topp-jørgensen e. & arnal m.f. 2021. interact reducing the environmental impacts of arctic fieldwork. aarhus: danish centre for environment and energy, aarhus university. harrowfield d.l. 2014. ‘for the sake of science and country’: the ross sea party 1914–1917. polar record 51, 343–365, doi: 10.1017/s0032247414000795. horst m. 2013. a field of expertise, the organization, or science itself? scientists’ perception of representing research in public communication. science communication 35, 758–779, doi: 10.1177/1075547013487513. hovelsrud g., veland s., kaltenborn b., olsen j. & dannevig h. 2021. sustainable tourism in svalbard: balancing economic growth, sustainability, and environmental governance. polar record 57, article no. e47, doi: 10.1017/s0032247421000668. iasc (international arctic science committee) 2022. the iasc state of arctic science report 2022. akureyri: iasc. ibarguchi g., rajdev v. & murray m.s. 2018. are current research funding structures sufficient to address rapid arctic change in a meaningful way? polar research 37, article no. 1540242, doi: 10.1080/17518369.2018.1540242. kerber j. 2022. tracing one warm line: climate stories and silences in northwest passage tourism. journal of canadian studies 56, 271–303, doi: 10.3138/jcs-2020-0006. larson e.j. 2011. an empire of ice: scott, shackleton, and the heroic age of antarctic science. new haven, ct: yale university press. lewis-jones h. 2017. imagining the arctic: heroism, spectacle and polar exploration. london: bloomsbury publishing. mallory m.l., gilchrist h.g., janssen m., major h.l., merkel f. provencher j.f. & strøm h. 2018. financial costs of conducting science in the arctic: examples from seabird research. arctic science 4, 624–633, doi: 10.1139/as-2017-0019. nasa earth observatory 2022. summer melting in svalbard. accessed on the internet at https://earthobservatory.nasa.gov/images/150165/summer-melting-in-svalbard on 28 april 2022. norwegian meteorological institute 2022. status of the sea ice—both in the south and in the north. accessed on the internet at https://cryo.met.no/en/sea-ice_status_sep2022_en on 28 april 2022. oceanwide expeditions 2022. otl08-22, trip log, east spitsbergen—arctic academy. accessed on the internet at https://oceanwide-expeditions.com/trip-log/otl08-22-trip-log-east-spitsbergen-arctic-academy on 26 april 2023. pedersen t. 2021. the politics of research presence in svalbard. the polar journal 11, 413–426, doi: 10.1080/2154896x.2021.1883900. powell r.c. 2007. “the rigours of an arctic experiment”: the precarious authority of field practices in the canadian high arctic, 1958–1970. environment and planning a 39, 1794–1811, doi: 10.1068/a38294. rantanen m., karpecho a. yu., lipponen a., nordling k., hyvärinen o., ruosteenoja k., vihma t. & laaksonen a. 2022. the arctic has warmed nearly four times faster than the globe since 1979. communications earth & environment 3, article no. 168, doi: 10.1038/s43247-022-00498-3. saville s.m. 2019. tourists and researcher identities: critical considerations of collisions, collaborations and confluences in svalbard. journal of sustainable tourism 27, 573–589, doi: 10.1080/09669582.2018.1435760. sees.nl 2022. sees expeditie 13–22 juli 2022. (sees expedition 13–22 july 2022.) accessed on the internet at https://www.sees.nl/2022/index.php?nr=194 on 28 april 2022. smits c.c.a., van leeuwen j. & van tatenhove j.p.m. 2017. oil and gas development in greenland: a social license to operate, trust and legitimacy in environmental governance. resources policy 53, 109–116, doi: 10.1016/j.resourpol.2017.06.004. stempniewicz l., kulaszewicz i. & aars j. 2021. yes, they can: polar bears ursus maritimus successfully hunt svalbard reindeer rangifer tarandus platyrhynchus. polar biology 44, 2199–2206, doi: 10.1007/s00300-021-02954-w. stephen k. 2018. societal impacts of a rapidly changing arctic. current climate change reports 4, 223–237, doi: 10.1007/s40641-018-0106-1. university of groningen 2002a. communication and outreach letter. the story of the spitsbergen expedition. accessed on the internet at https://www.rug.nl/research/arctisch-centrum/collaboration/dutchcollaboration/wbpi/.sees/scientist/communication-and-outreach-letter on 28 april 2023. university of groningen 2002b. arctic centre: new sees.nl expedition to spitsbergen in july. spitsbergen revisited from 13 to 22 july 2022. accessed on the internet at https://www.rug.nl/news/2022/04/arctic-centre-new-sees-nl-expedition-to-spitsbergen-in-july?lang=en on 28 april 2023. recent foraminifera in glaciomarine sediments from three arctic fjords of novaja zemlja and svalbard s . a . korsun, i. a . pogodina, s. l. forman and d. j . lubinski korsun. s . a,, pogodina, 1. a . , forman. s . l. & lubinski, d. j . 1995: recent foraminifera in glaciomarine sediments from three arctic fjords of novaja zemlja and svalbard. polar research, 14(1), 15-31. foraminifera were examined in recent (< 100 years) fine-grained glaciomarine muds from surface sediments and cores from nordensheld bay, novaja zemlja. and hornsund and bellsund, spitsbergen. this study presents the first data o n modern foraminifera distribution for fjord environments in novaja zemlja, russia. the data are interpreted with reference to the distribution of foraminiferal near svalbard and the barents sea. in nordensheld bay, live and dead noniortellino labradorica and islaniiiella norcr0sr.i are most abundant in the outer fjord. cassidulina reniforme and allogromiina spp, dominate in the middle and inner fjord. the dominant species are dissimilar to species occurring in other areas of the barents sea region, with the exception of svalbard fjords. the number of live foraminifera (24 to 122 tests/lo cm') in outer and middle nordensheld bay corresponds with values known from the open barents sea. however. the biomass (0.03 mg/lo cm') is two orders of magnitude less due to smaller foraminiferal test size, which in glaciomarine sediments reflects the absence of larger species, paucity of large specimens. and high occurrence of juvenile foraminifera. the smaller size indicates an opportunistic response to environmental stress due to glacier proximity. the presence of qubiquelocitlina stalkeri is diagnostic o f glaciomarine environments in fjords of novaja zemlja and svalbard. s. a . korsun and 1. a . pogodina, murmansk marine biological institute. 17 vladimirskaya st., murmansk 180023, russia; s . l . forman, b y d polar research center and department of geological sciences, the ohio state university, columbus. ohio 43210-1002, u . s . a . ; d . j. lubinski, institute for arctic and alpine research and department of geological sciences, university of colorado. boulder. colorado 80309-0450, u.s.a. (direct correspondence to s . l . forman). n ''*polar\ns''' introduction studies of foraminifera from recent glaciomarine sediments provide insights into the environmental significance of taxa and potentially improved paleoenvironmental inferences for fossil faunas. a number of studies have examined benthic fora minifera from svalbard fjords (goes 1892, 1894; kiar 1899; feyling-hanssen 1964; nagy 1965; rouvillois 1966; luczkowska 1975; elverhj et al. 1980; kirienko 1984; hansen & knudsen 1992; hald & korsun unpublished). in contrast, for aminiferal faunas from the subpolar fjords of novaja zemlja have not been investigated except for a study of reworked fauna from sea ice and icebergs (potekhina et al. 1992). glacier proximal foraminiferal assemblages in svalbard fjords are typically dominated by the calcareous species cassidulina reniforme and/or elphidium clavatum and have low values for fau nal diversity, planktic/benthic ratio, and number of tests (nagy 1965; luczkowska 1975; elverhd et al. 1980; kirienko 1984; hansen & knudsen 1992; hald & korsun unpublished). these assem blages are common in late pleistocene records from the southwestern barents sea and norweg ian shelf and are assumed to indicate glacier prox imity. the c. reniforrne-e. clauatum assemblages are replaced upcore, near the pleistocene/hol ocene transition, by a variety of other assemblages which indicate full marine conditions and pen etration of warm atlantic water into the area (e.g. bstby & nagy 1982; vorren et al. 1984; hald et al. 1989). in contrast, foraminiferal assemblages from holocene marine-muds in the northern barents sea are often similar to faunas from glacio-marine sediments of svalbard fjords, with co-dominance of c. reniforme and e . clav atum, and low faunal diversity, planktic/benthic ratio, and number of tests (sakharova & korsun 1989; spiridonov et al. 1992; korsun et al. 1994). our analysis of eight modern samples from nordensheld bay provide new data on the dis tribution of foraminifera in novaja zemlja fjords. these data comprise a basis for comparing and possibly extending established relations between 16 s . a . korsun et al. modern foraminifera in a novaja zemlja fjord with other areas in the barents sea region. for aminiferal test size and minor species composition hydrographic and sediment settings hornsund and bellsund, svalbard for glaciomarine sediments from nordensheld bay, novaja zemlja, and hornsund and bell sund. spitsbergen, were analysed to further evalu ate the differences between foraminifera1 faunas of the open northern barents sea and glaciated fjord environments o n the adjacent archipelagos. t h e west spitsbergen current, a northern branch of the gulf stream, transports relatively warm and saline (t > 1°c and s = 34.7%0) atlantic water along the western coast of svalbard (fig. 1). this water penetrates often at depth into fjords along the western coast of spitsbergen, 80" n 780 76" ,\ 70" f i g . i . l'hc bdrents sea region' atlantic ( 1 ) . arctic ( 2 ) . and coastal ( 3 ) surface currents (tantsiura 1y73. simplified): convergence zone ( 4 ) and mining zone ( 5 ) of the polar front ( t a n t m r a 1y7i): boreal/.arctic zoogeographic boundary of benthic foraminifcra ( h ) ( d i p \ 1971)) recent foraminiferain glaciomarine sediments 17 including hornsund and bellsund. during the winter, sea ice covers the fjord head and rarely extends to the open sea (vinje & kvambekk 1991). associated with sea ice formation at the fjord head is descending cold and saline (t < 0°c and s > 35%0) water. the summer melting of adjacent glaciers is a source of a low salinity (>20%0) surface layer in the upper 5 to 15 m (norman 1987; weslawski et al. 1991). the sedimentation rate decreases exponentially from many glacier termini o n western spitsbergen (elverhcji et al. 1983; boulton 1990). all three sampling sites are situated in the vicinity of calving glaciers (figs 2, 3 and 4) and within an area of meltwater discharge (august 1990). the con centration of suspended sediment at sampling site 15" e 20" d 1 fig. 2 . spitsbergen and location of study sites in bellsund and hornsund. ho-3 in hornsund, spitsbergen, ca. 0.5 km from the hansbreen outlet, was about 300 mg/l in the surface water in july 1983 (gorlich et al. 1987). sedimentation rate in the glacier-proximal zone usually does not exceed 350 mm/yr within 0.3 km from the hansbreen outlet and is less that 1 mm/ yr in the glacier-distal zone, approximately > 5 km from the glacier termini in hornsund (gor lich et al. 1987). nordensheld bay, novaja zemlja there is little information on water masses in the nordensheld bay area, novaja zemlja ("norden sheld" is a double transliteration, norwegian from russian to latin, of g . nordenskjdd name). the barents sea shelf in the vicinity of nordensheld bay is occupied by cold arctic water (t = 1°c and s = 34.8%0). nordensheld bay and the adjac ent shelf are usually covered by sea ice for at least six months of the year. (murmansk hydro meteorological survey 1988; vinje & kvambekk 1991). the only summer hydrographic profile is at site 874, which shows a lower salinity surface layer (0-10 m; 31.3-31.5%0) and normal marine values for bottom waters (34.8%0) (chinarina 1992). at the head of nordensheld bay is the large calving nordensheld glacier (fig 6). an extensive meltwater system emanating from the glacier ter minus delivers turbid fresh water to the fjord. although the exact sediment concentration is not known for the sampling period, an earlier investigation during august/september 1984 measured a water column suspended sediment (fine silty-clay) concentration of 88 mg/l ca. 10 km from the glacier terminus (aksyonov 1987). gla ciomarine sediments in the upper part of the fjord are characterised by 1 to 10 cm thick laminae of light gray silty-clay (tarasov et al. 1993). material and methods in nordensheld bay, northern novaja zemlja, four grab samples (896, 874, 894, and 895) and two gravity cores (894 and 895) were retrieved by the r/v dalnie zelentsy in late august and early september 1991 and four additional box-core samples (68/31, 68/3, 68/32 and 68/33) were col lected in august 1991. the distal samples (68/31, 68/3,68/32, and 896) have diagenetic colour strati fication, characterised by a 2-cm-thick light-olive 18 s. a . korsun et al. i 14'00' 1 4 ' 3 0 ' bellsund oxidised surface-layer. overlying light-gray mud. sediments. more proximal to the glacier (samples 874.894.68/33, and 895). d o not have an oxidised layer but consist of light-gray mud. both cores penetrated uniform laminated light-gray fine grained glaciomarine sediments (table 1: figs. 5 and 6 ) . three gravity cores (bel-1, ho-2. ho-3) from bellsund and hornsund were obtained by the w'v pomor in august 1990 (fig. 2 and 3). t h e recovered glaciomarine sediment is light gray with a low sand and gravel content (0.5-3%). t h e individual sediment cores were sampled at either 5. 10, or 20 cm intervals. t h e thickness of fig. 3. location of core bel-1 in bellsund. proximity to recherchebreen recherchehreen the sampled interval is 5 cm. the samples were dried, weighed, sieved (>0.063 mm), and floated with carbon tetrachloride to isolate foraminifera1 tests. t h e number of foraminifera counted for each sample ranges from 100 to 350 specimens. t h e greatest diameters of c. renifornie tests in core t o p samples (0-5 cm) of the fjord cores 894, 895, and ho-2 and the previously studied cores 671.666, and 396 from the open barents sea were measured to compare the mean test-size of an individual species in glaciomarine and marine sediments. c. reniforrne were chosen for the analysis because of its abundance in both the fjord and barents sea samples. t h e greatest diameter 15" 4 0 ' 16' 00' 16'20' fig. 4. location of core ho-2 in hornsund. recent foraminifera in glaciomarine sediments 19 table 1. station list sediment surface station collected date depth (m) sediment general location latitude n longitude e 6813 68/31 68/32 68/33 874 894 895 896 bel-1 ho-2 ho-3 653 646 396 666 67 i box core box core box core box core grab grab grab & core grab & core core core core grab grab core core core 8 / 19/92 8/30/92 8130192 8/30/92 8/18/91 8/29/91 8/29/91 8/30/91 samples investigated in this study nordensheld bay, 139 mud novaja zemlja 165 mud 120 mud 45 mud 76 mud 31 mud 49 mud 149 mud ,, i, i , ,, ,, ,i i, !i ,i i, ,i i, , i ,i belsund, w 40 mud spitsbergen hornsund. w 60 mud spitsbergen 30 mud it ,i 75" 28.0' 56" 44.2' 75" 33.3' 56" 21.1' 75" 28.5' 57" 10.0' 75" 21.5' 57" 35.8' 75" 22.0' 51" 29.0' 75" 19.7' 57" 30.2' 75" 20.0' 57" 45.0' 75" 24.7, 570 06.0, 77" 26.0' 14" 40.0' 77" 04.0' 16" 17.0' 77" 04.0' 15" 38.0' previously studied samples used for comparison 10/15/87 290 mud ne barents sea 10/12/87 200 sandy mud " ~ " 130 mud south off svalbard 380 mud 315 mud, pebbles " " i, i, 77" 37.0' 55" 57.0' 75" 58.0' 48" 13.0' 76" 58.6' 28" 12.1' 7.5" 55.0' 15" 54.0' 76" 10.0' 16" 21.0' 52o 56o 60' 64' 6 8 o 770 76o 7 50 740 730 72' 1 fig. 5 . locationof nordensheld bay onnovaya zemlja, russia. was measured for a minimum of 20 tests for each sample. the location of the previously studied cores is shown in fig. 1. foraminifera from eight modern samples (20 100 cm3 of the upper 1 cm) were preserved with 80% ethanol ( 5 : 1 by volume), assuming dilution to 70% due to the sediment water content. the samples were stained for one day with rose ben gal (1 g/l) and then wet sieved through 0.063 mm sieve. four samples from box cores (68/31, 68/3, 68/32, and 68/33) were dried and floated as above. live (stained) and dead (unstained) fora minifera were counted. the other four samples (896,874,894, and 895) were wet sieved to isolate the >1.0, 1 . 0 4 . 5 , 0.5-0.25, 0.25-0.100 and 0.100-0.063 mm fractions of foraminifera1 tests for a size class analysis and biomass measure ments. biomass is evaluated by a cytoplasmic volume calculation for four different size fractions. in each fraction a biomass was estimated by the following formula: w = 0.1 x s3 x n. where w = biomass, n = number of live fora minifera, and s = mean diameter of foraminifera 20 s. a . korsun et al. fig. 6. location of sampling sites in nordensheld bay, novaya zemlja, russia. (korsun 1991). means of the diameter (s value) for the following size fractions are: 0.0794 mm modern foraminifera in nordensheld bay, nooaja zendja (0.063-0. i mm fraction). 0.158 mm (0.1-0.25 mm fraction), 0.354 mm (0.25-0.5 mm fraction). and 0.707 mm (0.5-1.0 mm fraction). two previously studied grab samples from northeastern barents sea (646 and 653) a r e used to illustrate differences in nordensheld bav. t h e number of tests counted for each modern sample ranged from 35 to 416 specimens for total fauna from 17 to 148 specimens for live fora minifera. total fauna is the sum of live and dead foraminifera in modern samples. w e use the term ‘fossil’ for tests from the core samples. except for the core tops which are composed of live and dead foraminifera (total fauna). results a total of 59 foraminiferal taxa are identified for samples from novaja zemlja and svalbard (table 2 ) . most of the species are characteristic of arctic foraminiferal faunas of the barents sea region (digas 1970). foraminifera1 fauna includes organic-walled allogromiina spp., 23 arenaceous and 36 calcareous taxa. the only recent siliceous foraminifera known for the barents sea. s. groen landica, was absent in o u r samples of glaciomarine sediments. modern foraminifera were studied in eight surface sediment samples from nordensheld bay (fig. 6 ; tables 3 and 4). live and dead n . labradorica and i . norcrossi a r e abundant in t h e outer fjord (sites 68/31, 6813, and 68/32). c . renifornie and allogromiina spp. dominate in t h e middle and inner fjord. q. sralkeri occurs only in the middle and inner fjord. s. biformis and e . clavatum show unclear distribution patterns (fig. 7). t h e number of dead foraminifera comprises 152 t o 170 tests/10cm3 in the inner fjord and decreases consistently toward the glacier from 46 t o 1.5 tests/10cm3. t h e number of live fora minifera ranges from 24 to 122 tests/lo cm3 in the outer and middle fjord and drops to between 3 and 6 tests/l0 cm3 in the two samples closest t o the glacier terminus. calcareous faunas make u p 68 to 97% of live foraminifera in the outer fjord. in the middle and inner fjord, the percentage decreases from 77 to 8% toward the glacier, reflecting the increasing significance of allo gromiina spp. t h e percentages of dead calcareous foraminifera varies from 46 to 100% (fig. 8) and does not show consistent trends with position in bay. t h e total benthic fauna includes 12 to 35% of live specimens in the outer fjord; in the middle a n d inner fjord, the value exceeds 50%. t h e recent foraminifera in glaciomarine sediments 21 table 2. list of identified foraminifera1 taxa adercotryma glomerata (brady, 1878) allogromiina alueolophragmium crassimargo (norman, 1892) ammodiscus sp. ammotium cassis (parker, 1870) asfrononion gallowayi loeblich & tappan. 1953 boliuina pseudopunctatn hoglund, 1947 bolicrina sp. buccella frigida (cushman, 1922) cassidulina reniforme nsrvang. 1945 cibicides lobanclus (walker & jacob, 1798) cribrostomoides jeffreysi (williamson. 1858) denfalina baggi galloway & wissler, 1927 eggerella advena cushman, 1922 elphidiella arctica (parker & jones, 1864) elphidium albiumbilicatum (weiss, 1954) elphidium clavatum cushman. 1930 elphidium subarcficum cushman, 1944 episfominella sp fissurina marginata (montagu, 1803) fissurina sp. gavelinupsis praegeri (heron-allen & earland. 1913) globobulimina turgida (bailey, 1851) hippocrepinella alba heron-allen & earland, 1932 hyperammina subnodosa brady, 1884 islandiella helenae feyling-hanssen & buzas. 1976 islandiella norcrossi (cushman, 1933) lagena gracillima (seguenza, 1862) lagena semilineata wright, 1886 melon& barleeanus (williamson, 1858) miliolinella pyriformis gudina, 1969 miliolinella sp. neogloboquadrina puchyderma (ehrenberg, 1861) nonionella auricula heron-allen & earland. 1930 nunionella turgida (williamson, 1858) nonionellina labradorica (dawson. 1960) patenina corrrcgata williamson. 1858 pelosinu variabilis brady, 1879 polymorphinidae proelphidirtm niveum (lafrenz, 1963) profelphidiitm orbiculare (brady, 1881) proteeoriina sp. psammosphuera sp.2 quinqueloculina stalkeri loeblich & tappan. 1953 recurvoides rurbinatus (brady, 1881) reophax arctica brady, 1881 reophax atlantica (cushman, 1944) reophax scorpiurus montfort, 1808 reophax scotfii chaster, 1892 robertina arctica d o r b i g n y , 1846 rosalina spp. rotaliammina ochracea (williamson, 1858) spiroplecramminn biformis (parker & jones, 1865) stairzfortlria loeblichi (feyling-hanssen. 1954) stainforthta schreibersiana czjzek, 1848 textularia earlandi phleger, 1952 terttularia rorquata f. parker. 1952 trifarina puens (todd, 1947) trochammina nana (brady, 1881) trochamminella atlanrica f. parker. 1952 trochamminella brrllara hoglund, 1947 trochamminella sp. number of live species per sample decreases gradually toward the glacier. the number of dead species is 22 to 23 in the outer fjord and 2 to 8 in the middle and inner fjord. (table 4; fig. 8). foraminifera1 biomass is evaluated for four samples (896,874,894, and 895) and ranges from 0.001 to 0.030 mg/lo cm3. the lowest value is observed in the sample closest to the glacier ter minus (table 4). an analysis of size spectra in these four samples reveals that neither live nor dead foraminifera occur in sieve fractions greater than 0.25 mm. recent foraminifera in cores f r o m nordensheld bay, novaja zernlja, and hornsund and bellsund, svalbard we infer that the sampled sediments in close proximity to present glacier margins were deposited in the last few hundred years. sedi mentation rates near core site ho-3, hornsund, are approximately 350 mm/yr (gorlich et al. 1987) and thus, the 60-cm-length of sampled sedi ments probably spans < 10 years. the proximal core site 895 in nordensheld bay is located behind the end moraines of a presumed little ice age advance of nordensheld glacier (fig. 6; forman unpubl. data). we speculate that the sediments at site 895 were deposited after the glacier retreat ca. 1900 a . d . in the upper part of nordensheld bay, individual sediment laminae are from 1 to locm thick. tarasov et al. (1993) assumed that the laminations were seasonal, and thus the two studied cores may span decades or centuries. we estimate that the sedimentation rate for the cores studied is two to three orders of magnitude higher than in the central barents sea where the appar ent holocene sedimentation rate is approximately 0.1 mm/yr (gataullin et al. 1993). the downcore distribution (figs. 9 and 10) illustrates the general continuity and short term variations of taxa in these sediments. the dominant species in the five studied cores are c. reniforme and e . clavatum (figs. 9 and 22 s. a . korsun et al. table 3 number of live and dead foraminifera per 10cm' in nordensheld bay. novaja zemlja station 68/31 68:3 68/32 896 874 894 68/33 895 live l l l l l l l l dead d d d d d d d d allogromiina spp. hippocrepirtella alba psuinrnospliaeru sp.2 proreoninu \ p . pelosina ouriuhilis hyperamrriiriu subnodosa ammodurw s p . r e o p h a r aflunticu reopliax s l ( ~ r p i u r ~ reop1ia.x urrticu reophux scorrii ammoriuni 1us1.1 a l v e o l o p h r u g m i u m crassintargo cribrosromoides jejjreys i adercorrwnu glomerara recuriwides rurbinuricc trochuniinrnella hullaru irochammiita nuna .spiroplecrurni~iirta hiformi\ €ggrrrlla urloenu c'orniupira , p . ~ i i i r i q i i e l o ~ ~ i r / i ~ i u srulkerr miliolinellu sp qhicider ioburulro kosulina s p . buctelh frrgidu .voniuriellinu lubrudoriro .4srronoiirori gullonq i proteiphrdiiirn orhicirlure e l p h i d i i r i n riihar~~iicurn elphiiliuni ~ ~ i r i t ~ u r i i ~ n cu.5 ~ i d u l i n u rrrii jo rinr 1.0 1.0 2.5 2.5 1.5 1.5 i n 0 52.0 26.5 3.0 2 0 6 0 10.5 0 4 2.0 1 .0 0.3 0 5 0.2 18.0 1.5 0.5 0 . 5 0.5 3.5 1.0 1.0 3.0 1.5 7.0 0.5 0.5 4.0 4.0 2.0 6.5 33.5 0.5 0 5 2.0 0.5 1 .o 0.5 2 . 5 8.5 1 . 0 15.5 1 .o 1 0 6.0 0 . 5 10.5 5 . 5 1 .o 0 5 2 0 2 5 0.5 1 0 2 5 4 . 5 0.5 2.0 2.5 2.5 6.0 10 0 0.7 3.0 0 5 14.0 6 . 0 2.5 0.5 7.0 2 . 0 6.5 2.0 0.1 2.0 0.5 0.3 1 .0 4.0 0.3 0.3 0.5 2 . 5 2 . 0 9.0 1 0 10 5 6.0 2 1 . 5 7 5 2 1 ( 1 i4 0 1 5 10.5 3.0 11 0 0.5 0 . 5 j.5 2.0 0.5 1 5 1 .u 78 5 i4 0 6 5 7 5 1 .0 34.5 29 0 6.5 5 0 2.0 6.5 1.0 2 . 0 1 . 5 0.3 0.4 28 0 8.0 1 . 5 2.0 0.5 50.0 52 0 6.0 0.7 0. i 0 5 6.5 9 0 recent foraminifera in glaciomarine sediments 23 table 3 . continued ~ ~~ station 68/31 6813 68/32 896 874 894 68/33 s95 live l l l l l l l l dead d d d d d d d d islaridiella riorcrossi + islandiella helenae 11.0 13.5 bolivina pseudopicnctata 1.5 10.0 19.5 31.5 0.5 trifarina pueris 0.5 0.5 0.5 1.0 3.0 stainforrli ia ioeblich i 0.5 2.5 globobulimina ticrgida 0.5 dentalina baggi 0.5 stairiforrhia schreibersiana robertina arctica 0.5 0.5 lageria sernilinema 0.5 6.0 1.5 0.1 10). t h e arenaceous foraminiferan s. biformis and the calcareous foraminifera q. stalkeri, c. lobatulus. buccella frigida, and n . labradorica in some intervals comprise > 15% of the fauna. t h e ambiguous morphology ( 2 o r 3 chambers) of many small-sized (ca. 0.063 mm) juvenile tests preclude identification to genus. these smaller tests com pose up to so% of the fauna in certain levels and table 4. faunal and environmental characteristics of the foraminifera1 distribution in nordensheld bay. novaja zemlja (n/a = none analysed) station 68/31 6813 68/32 896 874 894 68/33 895 live l l l l l l l l dead d d d d d d d d benthics/io cm3 9% calcarcous foraminifera calc/lo cmj live calc./total calc. benthics counted no. of species, all no. of species, calcareous % live biomass, mg/lo cm3 23.5 68 16.0 170 0 46 78 0 0.17 3’0 23 10 47 13 5 12 n i a 47.0 93 43.5 151.5 81 123.0 0.26 264 22 11 72 10 7 24 n/a 87.5 97 84.5 165.5 91 150.5 0.36 268 22 12 148 11 8 35 n/a planktics counted (neogloboquadrina pachyderma sin) distance from glacier. km 48 36 25 % sediment fraction >0.063 mm 5.4 7.4 4.5 1 sea depth. m 165 139 120 94.0 77 72.0 46.0 70 32.0 0.69 23 5 3 47 9 5 67 0.021 24 149 2.5 122.0 52 64.0 10.0 100 10.0 0.86 5 2 2 61 5 3 92 0.030 12 76 0.9 73.5 24 18.0 13.5 78 10.5 0.63 27 8 5 147 10 6 84 0.029 10 31 0.3 5.7 6.0 83 5.0 0.29 18 6 5 35 2.0 17 5 3 49 n/a 7 45 0.3 2.6 8 0.2 1.5 67 i .i) 0.17 15 5 3 26 4 2 63 0.001 3 49 0.1 24 s. a . korsun et al. _ _ _ _ _ _ _ _ _ _ _ _ _ _ cassidubna renilorme . . . . . . . . . . . . . . . . . . . . r g 7 the distribution of live dead benthic foraminifera (tests/lo cm3) in nordensheld bay, novala zemlja (collected i n . . . . . . . . . . . . . . . . . . . . _ _ _ _ _ _ _ _ _ _ _ _ _ . . . . . . . . . . . . . . . . . . . . 68/31 68/3 68/32 896 874 894 68/33 895 late august and early station are referred t o as ‘varia uv.’ (figs. 9 and 10). t h e number of benthic species/sample and number of tests/100 g d o not exhibit consistent downcore trends. planktic foraminifera a r e rare in fjord sediments. reflecting the limited number of trans ported tests. the abundance of foraminifera appears to increase with distance from the main outlet glacier i n fjords o n spitsbergen and novaja zemlja. cores ho-3 and be-1 from hornsund and bell sund collected within 0.5 km from the outlet gla cier terminus at water depths of 30 m and 40 m , respectively. have a foraminifera abundance of septeniher 1990 and 1991). < 100 test/100 g of sediment (fig. 10). in contrast, core ho-2. collected at ca. 2 km from the main outlet glacier at a water depth of 6 0 m has an abundance exceeding 200 tests/100 g (fig. 10). a similar trend in foraminifera abundance is also recognised for glacier proximal and distal sites in nordensheld bay, novaja zemlja (fig. 10). cassidulina reniforme test size initial observations indicated that tests of an indi vidual species from fjord environments a r e smaller than tests from the barents sea. a series recent foraminifera in glaciomarine sediments 25 150 100 50 0 no. of species per sample oxidized surficial sediment layer +----present absent __* fig. 8. selected faunal and environmental characteristics of the foraminifera1 distribution in nordensheld bay, novaja zemlja (collected in late 8,0 % sediment fraction >0.063 mm august and early 68/31 6813 september 1991 and 1992). of comparative measurements of c. reniforme tests from fjord and barents sea environments were undertaken to quantify these observations (table 5 ) . intersample differences in mean test size for glaciomarine and marine sediments are insignificant (fig. 11). in contrast, the difference between the mean of the greatest c. reniforme diameter from glaciomarine sediments and the mean value for marine sediments is significant at the highest standard confidence level, tfact = 6.20 > to,ool = 3.29. tests are considerably larger in the barents sea, averaging at least 40 pm larger diameters than fjord specimens (fig. 11). there are distinctive differences between nor densheld bay foraminifera assemblages from the open barents sea and the coastal zone of kola peninsula, svalbard, and franz josef land. these near-shore areas are situated to the north of the boreal-arctic zoogeographic boundary of fora minifera (fig. 1; digas 1970). in comparison with novaja zemlja. the svalbard fjords are similar in terms of presence of meltwater plums in the vicin 26 s. a . korsun et al. 895 ( 4 5 m) ! 8 9 4 ( 3 1 m) 1 -i+ = = = 1 -- ore no (sea depth) listancs from glacier weight % of sediment ~ fraction >o 063 mm sample, depth in core (cm) allogromiina spp hrppocreprnella alba reophax arctrca trocharnrninella etlantrca rotaliarnrnina ochracee sprropleclarnmina brforrnrs eggerella advena ournqueloculina slalkerr mrlrolmella pyrrformrs patellma corrugata cibicrdes lobatulus rosalrna spp gavelrnopsrs praegerr buccella frigida eprstornrnella sp nonronella auricula nonionellrna tabradorica melonis barleeanus astrononion gallowayi protelphtdrum nrveum elphidturn albrumbrlrcaturn elphrdiurn subarcticurn protelphrdrum orbiculare elphrdium clavaturn cassrdulrna renrforme lslandislla helenae lslandrella norcrossi trrfarrna fluens starnforfhia loeblrchr stainforthfa schrerbersran. bolivrna pseudopunctale polymorphinidae spp lagena gracrllrrna fissurrna margrnata varia uv 2 n pachyderma dex .a n pachyderrna sin -a _ -0 ~ 0 number of benthic n foraminifera per loog ) ;;o 0 of dry sediment ,n number of species ity of the subpolar glaciers. t h e kola peninsula does not have tidewater glaciers or any glaciers in vicinity of the coastline. although franz josef land is almost entirely covered by ice caps. these polar glaciers produce rare melt water plums. in nordensheld bay. n . labradorica and i . norcrossi are the most abundant species in the outer fjord (68/31.68/3. and 68/32). c. reniforme and allogromiina spp. dominate foraminiferal fauna closer to nordensheld glacier (fig. 7). these taxa generally comprise a low percentage of the total foraminiferal fauna in the open bar ents sea (digas 1970: korsun et al. 1994), the coastal zone of the kola peninsula (korsun 1986. 1992) and franz josef land (basov 1961; lukina 1y77). fig. 9. foraminifera1 distribution i n cores 895 and 894 from nordensheld bay, navaja zemlja. t h e r e are broad similarities in the distribution of foraminifera in nordensheld bay and the fjords of svalbard. n . labradorica and c. reniforme are two of six principal species identified from six fjords o n western and northern spitsbergen (hald & korsun, unpubl.). c. reniforme appears to inhabit environments closer t o the fjord head while n . labradorica increases in abundance out fjord. c. renifornte is an opportunistic species and often dominates foraminiferal assemblages in htressed/unstable environments proximal to gla cier discharge (e.g. osterman & nelson 1989). w e assume that t h e substitution of n . labradorica and i . norcrossi by c. reniforme in nordensheld bay reflects increasing ecological instability toward the glacier. recent foraminifera in glncioninrine sedinients 27 2 0 0 n u m b e r o f b e n t h i c f o r a m i n i f e r a per 1 0 0 g . of dry s e d i m e n t 0 2 ul 0 20 7 10 number of s p e c i e s i 2 r 0 i s v e fig. 10. foraminifera1 distribution in cores be-1, ho-3, and ho-2 from bellsund and hornsund, svalbard. c o r e n o ( s e a d e p t h ) d i s t a n c e f r o m g l a c i e r n w e i g h t yo of s e d i m e n t f r a c t i o n >0.063 mm s a m p l e . d e p t h in c o r e ( c m reophax scottii adercotryma glomerata trochamminella sp. spiroplectammina biformis eggerella advane ouin ueloculine stalkeri pate&na corrugate cibicidas lobatulus rosalina app buccella lrigida nonionelline tabradorica melonis barleeanus astrononion gallowayi elphidium subarcticom elphidium clavatum cassidulina reniforrne lslandiella helenae sleinlorlhia leoblichi bolivina sp. polymorphinldaa spp. lagena gracillima fissurina sp. varia uv. n. pachyderm8 dex. n. pachyderm8 sin. c . reniforrne and another characteristic glaciern u m b e r of live foraminifera and biomass in proximal cakerous species, e. clavatum, conordensheld bay dominate in outer and middle nordensheld bay (st, 68/31 densheld (fig. 9, and calthrough 894), the glaciomarine mud contains 24 in the two nor careous assemblages in grab samples 894 and 895 distribution of e . clavatum in nordensheld bay remains unclear. to 122 live specimens/l0 cm3 (fig, 8). this is barents sea where values mainly range from 25 to 200 with a mean of 90 tests/lo cm3 (korsun et 3). the dominant on the similar to sandy and muddy sediments of the open tuble 5 . a comparison of mean greatest diameter of cussidulinu reniforme test in glacimarine and marine sediments. x diameter, se standard error. n number of tests table 6. number of calcareous foraminifera in grab and core samples from two sites in nordensheld bay, novaja zemlja (tests per 100 g dry sediment) station x (pm) se n general location marine sediments 67 1 206.7 8.0 30 w barents sea 666 203.4 7 . 8 22 w barents sea 396 194.4 5.4 40 w barents sea glacimarine sediments ho-2 147.9 8.6 24 hornsund. w spitsbergen 894 168.5 6.8 50 nordensheld bay, n.z. 895 161.4 1 1 3 22 nordensheld bay, n.z. station 894 895 grab (0-1 cm) total 200 8 live 63 % 17% mean ? se 282 5 100 54 2 13 min 78 13 max 891 15 1 core core top (0-5 cm) 891 52 28 s. a . korsun e t a l . diameter, prn 671 6 6 6 396 h o 2 8 9 4 895 station big. i 1 hlean greatest diamctsr of the c'assiduhiio renifonnr test i n g l ~ i o m a r i n e and marine sediments. bar = y j c i con fidence intc'rval al. 1994). in contrast, the biomass in the middle of nordensheld bay (0.03mg/10cm3) is two orders of magnitude less than the biomass in adjacent areas of the sea (fig. 12). t h e larger (> 1 m m ) arenaceous foraminifera such as rhab dammina abyssorrcm (sars, 1868). hypperammina subnodosa, pelosina uariabilis are common in muddy barents sea sediments and constitute the majority, ca. 9 0 7 ~ . of t h e foraminiferal biomass (korsun e t al. 1994). such larger species or any foraminifera >0.250 mm in diameter are not 0 5 f 5 0 2 0 0 l . 2 0 2 5 4 0 1 5 0 10 0 05 0 found in nordensheld bay. d u e t o the smaller test size, t h e foraminiferal biomass is significantly lower in nordensheld bay t h a n in t h e open bar ents s e a though the number of live specimens is similar (fig. 12). macrofauna biomass is low (< 1 g/m?) in glacier-proximal sediments with seasonal lami nations in hornsund (gorlich et al. 1987). t h e laminations indicate the absence of bioturbation and hence. an inhibited macrobenthos (giirlich et al. 1987). w e infer that foraminiferal biomass shows a similar decrease in nordensheld bay, novaja zemlja. foraminiferol test size t h e analysis of foraminifera from novaja zemlja and svalbard fjords shows test size diminishing in t h e glaciomarine sediments compared to marine sediments from the open barents sea. in the glaciomarine sediments of nordensheld bay. for aminiferal tests a r e absent in sieve fractions >0.25 mm. in contrast, all of thirty-six for aminiferal samples from the open barents sea have a number of specimens larger than 1 mm (korsun 1991). the studied cores show smaller test size from glaciomarine sediments, indicative of juvenile specimens. a high occurrence (up to 5 0 7 r ) of these small foraminifera has not been observed in holocene sequences from the open barents sea ( 0 s t b y & nagy 1982; korsun et al. 1994; among others). t h e high frequency of juv enile tests indicates a high mortality in the fossil populations. feyling-hanssen (1982) noted that barentssea nordensheld bay 4 + 4 c 2 0 biomass ' size 1 class v1 rl mrn c 0 5 1 : 0 25-0 5 foraminifera 646 653 896 87 4 894 895 s t a t ion 1 5 0 125 n 100 $ \ v) 7 5 5 a 2 50 foraminiferal biomass fig. 1 2 . sizc distribution of (cytoplasmic volume) and number of live foraminifera 25 in nordensheld bay. novaja zemlja. two 0 samples from the northeastern barents sea are shown for comparison. recent foraminifera in glrcioniarine sediments 29 e . clavatztm specimens from glacial deposits are smaller in comparison to tests from full marine environments. our results show that the other foraminifera, typical of glaciomarine settings, c. reniforme (osterman & nelson 1989), demon strate a similar tendency and the difference is highly significant. the linear size of c. reniforme tests in glaciomarine sediments of nordensheld bay (novaja zemlja) and hornsund (spitsber gen) is 20% smaller than in marine sediments of the open barents sea. we presume that the smaller size of fora minifera in the glaciomarine sediments is an example of the opportunistic response to an environmental stress. in fjords influenced by gla cier discharge, the inferred environmental par ameters affecting benthic populations are meltwater discharge and high sedimentation rates (appolonio 1973; pierson 1980; gdrlich et al. 1987). intrusion of particulate rich meltwater into the bottom part of the water column is uncommon in glaciomarine environments (gilbert 1983). meltwater usually occupies the upper part of the water column and indirectly effects benthos com munities via diminishing the primary production in the plankton community, that reduces organic flux to the bottom (gorlich et al. 1987). we favour high sedimentation rates as the dominant controlling factor for diminishing foraminiferal test size. rapid settling of sediment and turbidite deposition may continuously disturb benthos communities burying the fauna and maintain the benthos community at an early stage of the suc cession. such pioneer communities are charac terised by high mortality of immature specimens and typically consist of opportunistic species which have a small size and a short life cycle (odum 1971). the foraminiferal test size decreasing in the studied glaciomarine sediments versus the full marine sediments in the open barents sea is expressed in the absence of larger species, paucity of large specimens, and high occurrence for juv enile foraminifera. this difference may be useful as another indicator of glaciomarine settings in paleoreconstructions. rare species the foraminiferal fauna in the studied glacio marine sediments (table 2) is represented mostly by taxa characteristic of the arctic zoogeographic province of the barents sea (digas 1970). there are two species whose presence is quite unusual for the barents sea region, p. niveuin and q. stalkeri. we found the first species, p. niueum, in both cores from nordensheld bay but not in the mod ern samples. 'this species has not been registered in the surface sediments of the open barents sea (digas 1970; steinsund et al. in press). several tests (unstained) have been observed in the inner part of yarnyshnaya bay, kola peninsula, 69"07'n, 36"03'e (korsun 1986). live specimens of this foraminifera are only found in two shallow water sites at 4 and 1 2 m on franz josef land (korsun unpubl. data). the limited occurrence of this species precludes an environmental inter pretation. q. stalkeri is present in the modern samples and in all the cores except for ho-2. it is a sub dominant or dominant species in several samples (figs. 7 , 9, and 10). this species is quite rare in the open barents sea. in the total calcareous foraminiferal data set for the barents and kara seas (598 samples; steinsund et al. in press), q. stalkeri occurs (about 1%) only in 10 samples from the open sea. no live specimen of this species is found in sixty samples from the open barents sea (korsun et al. 1994). q. stalkeri has been registered neither in the kola peninsula bays (schedrina 1958: korsun 1986,1992) nor in franz josef land (basov 1961; lukina 1977). in contrast, q. stalkeri is common in surface sediments from svalbard fjords (nagy 1965; e l v e r h ~ i et al. 1980). this species, including live specimens, was identified in six fjords on western and northern spitsbergen and composed up to 14% of the total fauna (hald & korsun, unpubl.). although, q. stalkeri has been supposedly found in a variety of near-shore environments (feyling-hanssen et al. 1971), the occurrence of the species in the barents sea region seems to have some connection to modern fjord environ ments of novaja zemlja and svalbard. q. stalkeri is possibly an indicator of glaciomarine depo sitional environments. conclusion n . labradorica and i. norcrossi reach peak abun dance in the outer fjord samples. c. reniforme and allogromiina spp. dominate foraminifera in the middle and inner fjord, closer to the glacier outlet. the foraminiferal dis 30 s . a . korsun et al. tribution and changing dominance of species in nordensheld bay is similar t o svalbard fjords that are affected by glacial discharge. ecological stress is probably caused by the high and changeable sedimentation rate and meltwater flux (c.f. gor lich e t al. 1987). q. stalkeri is frequent in novaja zemlja and svalbard fjords compared to the other areas of the barents sea region as a possible indicator of glaciomarine settings. in nordensheld bay, the number of live fora minifera in the outer and middle fjord (24-122 spec./lo cm3) is similar t o the values from the open barents sea, whereas the biomass (0.03 mg/ 10 cm3) is two orders of magnitude less d u e to a smaller test size. tests of c. reniforme are significantly smaller in glaciomarine sediments than in marine sedi ments in t h e barents sea. glaciomarine sedi ments have in general a noticeable lack of large tests and species and an abundance of juveniles. the smaller test size is an opportunistic response of the foraminiferal populations to the environ mental stress of glacier proximity. ackiiowledgemenrs. g . a. tarasov supplied cores from bellsund and hornsund fjords early reviews by g . g . matishov. p.-i. steinsund. m. hald. j snvder. p n. webb. a . reed and d . rodbell were helpful in focusing the discussion. c. hart and j . snyder absisted with translation. we gratcfull? acknowledge the captains and crewt of the r v d a l h l e zelents? and r \ pomor for probiding a reliable sampling platform. this research w a s partially supported by the u . s . national science foundation grant dpp-w)1471 and the office of naval research contract n00014-97-1908. we appreciate the draftman\hip of j . nag! and word-processing assistance of s j . harrk. this i s bprc contribution #948. references aksyonov. a . a . (ed.) 1987: the a r c f i c s h e l f o f eurasia during rhe lore qitareriiary. nauka. moscow. 278 pp. (in russian). appolonio. s. 1973: glaciers and nutrients in arctic beas. science 1xo. 491-49.2 basov. v a . 1961: composition and distribution of fora minifcr;i in sediments from franz josef land. liuclx n i l c a i 2 4 . 61-h5. ( i n russian) boulton. g s 1990: sedimcntar! and sea level changes during glacial c!clc\ and their control o n glaciomanne facies archi tecturc pp i s 5 3 in doadeswell. j . j . & scourse. j . d. (eds. ) ' glut-roinarrire t t i i w o n m e n r s . process and sediiiieiits. geological society. a \ o n . united kingdom. chinarina. a . d . ( e d . ) 1992: c o m p l e r inrernariorial expedirioti of rhe mtrrrnonsk mariiie biological itistititre inro area.< of high-lotirnde nrchipelogors of rlie barenrs sea (fruti; josef 1.und irnd n o o a y a zemlvu. apatity. 54 pp. ( i n russian with enzlish abstract) digas, l. 1970: zoogeographic zonation of the barents sea on foraminifera [zoogeograficheskoe rajonirovanie barentseva morja po foraminiferam. pp. 127-142 i n v o p r o s y geologii juzhiiogo u r d u i pociolzh'ja. saratov university, saratov, russia. (in russian). elverhqi. a , , liestol. 0. & nagy. j . 1980: glacial erosion, sedimentation and microfauna in the inner part of kongsfjor den. spitsbergen. n o r s k p o l a r i m t . skrifter 172, 3 3 6 1 . e l v e r h ~ i . a , , l ~ n n e . 0. & seland. r . 1983: glaciomarine sedimentation in a modern fjord environment, spitsbergen. polar res. 1 . 127-149. feyling-hanssen. r . w., 1964 foraminifera in late quat ernary deposits in the oslofjord area. norges geol. unders. 2 2 5 . 383 pp. feyling-hanssen. r. w . 1982: foraminiferal zonation of a boring in quaternary deposits of the northern north sea. bull. g e o l . soc. denmark 31. 2%41. feyling-hanssen. r . w.. j ~ r g e n s e n , j . a . . knudsen, k . l. & andersen. a l . l. 1971: late quaternary foraminifera from vendsyssel, denmark and sandnes. norway. bull. geol. soc. d e n m a r k 21 f2-3). 67-317. gataullin. v . n . , polyak. l . v . . epstein. 0. g . & romanyuk, b. f. 1993: glacigenic deposits of the central deep: a key to the late quaternary evolution of the eastern barents sea. boreas 22. 47-58. gilbert. r . 19x3: sedimentary processes of canadian arctic fjords. sedimen. g e o l . 36. 147-175. goes. a , . 1892: rhizopodia reticulata insamlade vid spits bergen 1890. p p . 77-78 in nordrnskiold, g . (ed.): redo gorelse for den svenska expedisjonen till spitsbergen. siwnska v e r e i i s . a k o d . hatidl. bihanga 1 7 . 77-78. (in swed ish). goes. a , . 1894: a synopsis of the arctic and scandinavian recent marine foraminifera hitherto discovered. suenska vereris -akud h a n d l . 25, 1-127. gorlich. k.. weslawski. j . h.1. & zajaczkowski. m. 1987: sus pension settling effect on macrobenthos biomass distribution in the hornsbund fjord, spitsbergen. polar res. 5 n . s . , 175 192. hald. m.. danielsen. t. k . & lorentzen, s . 1989: late plei stocene-holocene foraminiferal distribution in the south western barents sea: paleoenvironmental implications. boreas 18. 367-388. hansen. a . & knudsen. k . l. 1992: recent foraminifera in freemansundet. eastern svalbard. pp. 177-189 in m ~ l l e r , p., hjort. c . & ingolfsson, q . (eds.): weichseliaii & holocene glacial mid marine history of easr sualbord: preliminarv report on the ponam fieldwork i i i 1991. lundqua report 35. kirienko. e . a . 1984: holocene foraminiferal assemblages from the isfjorden. spitsbergen. proceediiigs of leningrud u n i iwsin. series 6 g e o l o g y and g e o g r a p h y 1 . 56-69. (in russian). kirer. h . 1899 talamophora. den norske nordhavb-eksrdition. 18761878 zoologi 7 ( 2 5 ) . 1-13 korsun. s. a . 1986: modern foraminiferal assemblages of an open fjord-like inlet. eastern murman. pp. 176-184 in: quaf ernor! paleoecology a n d paleogeography of northern s e a s nauka. moscow. ( i n russian with english abstract). kortun, s . a . 1991: foraminifera1 biomass evaluation: deter mination of average test volumc in different sieve fractions. pp. 81-93 in: iriformalion science and srutcftics in h y d r o biological srudies of rhe barenrs sea. kola science center publishers, apatity. russia (in russian with english abstract) korsun. s . a . 1992: foraminiferal distribution i n the estuary recent foraminifera in glaciomarine sediments 3 1 of rynda river, eastern murman, barents sea. pp. 150-170 in: problems of c e n o z o i c paleoecologj and p a k o g e o g r a p h y of seas of the polar ocean. nauka, moscow. (in russian with english abstract). korsun, s. a , , pogodina. 1 . a . , tarasov, g . a. & matishov, g. g. 1994: foraminifera of the b a r e m sea (hydrobiology and quaternary paleoecology). kola science center pub lishers. apatity, russia. 250 pp. ( i n russian with english abstract). luczkowska, e. 1975: middle holocene foraminifera from hornsund, spitsbergen. stiddin geologica polonica 4 4 . 9 s 114. lukina, t. g. 1977: foraminifera of the upper parts of the shelf near franz josef land. pp. 72-105 i n : biocoenoses of franz josef l a n d and fauna of adjacent shelf. sfudies of fauna of seas 1 4 . 2001. inst., leningrad, russia. ( i n russian with english abstract). murmansk hydrometeorological survey, 1988: information on water temperature of the barents sea. murmansk, russia 100 pp. (in russian). nagy, j . 1965: foraminifera in some hottom samples from shallow waters in vestspitsbergen. norsk polarisnf. a r b o k 1963, 109-128. norman. u . 1987: hydrografiske observations fra svalbard, 1984. 1985. tromura 53. 129 pp. odum. e. p. 1971: fundamentals of ecology. 3rd ed., w. b. saunders co., philadelphia. p. 740. bstby k. l . & nagy .i. 1982: foraminiferal distribution in the western barents sea. recent and quaternary. polar res. 1, 53-95. osterman, l. e . & nelson, a . r 1989: latest quaternary and holocene paleoceanography of the eastern baffin island continental shelf, canada: benthic foraminifera1 evidence. c a n . 1. earth sci. 26. 22362248. pierson, t . h . 1980: macrobenthos of fjords. fjord ocean ography, n a t o publ. series. potekhina e. m . , khusid, t . a , , & relyaeva n. v . 1991. foraminifera and mineral particles in sea ice from bays of northern island of novaya zemlya. bull. m o i p . geol. 6 6 ( 2 ) , 12&127. rouvillois, a , , 1966 contribution a i'itude micropaleon tologique de la bai du roi. au sptizberg. reoire des micro paleonolgie 9, 169-176. sakharova, i. a . & korsun, s . a . 1989: productivityoscillations and biostratigraphy of northern seas. foraminiferal analysis. pp. 65-82: in: quateriiar)j paleoecology and geology of the northern european seas. kola science center publishers, apatity, russia. (in russian with english abstract). schedrina 2. g. 1958: foraminifera of eastern murman. publ. murmansk biol. station 4 , 118-119. spiridonov. m. a , , rybalko. a . y. & polyak, l . v . 1992: late quaternary stratigraphy and paleogeography of the eastern barents sea off central novaya zemlya. pp. 47-68 in spi ridonov, m. a . & rybalko. a . y . (eds.): sedimentary cover of glaciated shelf, north-western seas of russia. ( i n russian). steinsund, p. i.. polyak, l.. hald, m., mikhailov v . , & korsun, s . : recent distribution of calcareous benthic foraminifera i n the barents and kara sea. j . foram. res. in press. tantsiura, a . i . 1973: on the currents of the barents sea. transactions of the polar scientific research institunon of marine fisheries and oceanography n . m . ktiipoiri ( p i n r o ) . in russian, translated to english by the norwegian polar institute. oslo. tarasov g . , nurenberg d . , grot e.. & khasankaev n. 1993: the bottom sediments. pp. 22-26 in: reports on the inter national multi-disciplinary cruise t o high-latitude archipel agoes of the barents sea (franz josef l a n d and noiiaya z e m l y a ) . kola science center publishers, apatity, russia. vinje. t . & kvambekk. a . s . 1991: barents sea drift ice characteristics. pp. 9-68 in sakshaug, e . , hopkins. c. c. e. & britsland. n. a. (eds.): proceedings of the pro mare symposium on polar marine ecology, trondheim, 12-16 may 1990. polar res. i o ( 1 ) . vorren t. o . , hald. m., & thomsen, e . 1984: quaternary sediments and environments on the continental shelf off northern norway. m a r . geol. 57, 22f257. weslawski, j . m . , jankowski, a , . kvasniewski, s . , swerpel. s . & ryg, m. 1991: summer hydrology and zooplankton in two svalbard fiords. polish polar res. 12, 445-460. modeling synthetic aperture radar (sar) scattering from a seasonally varying snow-covered sea ice volume at 5.3 and 9.25 ghz david g . barber and ellsworth f. ledrew barber, d. g. & ledrcw. e. f. 1994: modeling synthetic aperture radar (sar) scattering from a seasonally varying snow-covered sea icc volume at 5.3 and 9.25 ghz. polar research 13. 35-54. a scrics o f scnsitivity analyses using dielectric, mixture and microwave scattering models is presented. data from thc seasonal sea ice monitoring and modeling site (simms) in 1990 and 1991 are used to initialize the models. the objective of thc research is to investigate the role of various geophysical and clcctrical properties in spccifying the total relative scattering cross section (u") of snow covered first-year sea ice during thc spring period. thc scasonal transition period from the winter sar scattering season to early melt was shown to signal a transition i n dielectric properties which caused the snow volumc to become a factor in the microwavc scattering process. thc effcct of the thermal insulation of a snow coveron sea ice was shown to be significant for both e' and e". highcr atmospheric tcmperatures caused proportionally greater changes in the dielectric propcrtics o f the sea ice at the base of thc snow cover. model u" was computed for a range of scnsor. scnsor-earth geomctry. and geophysical propcrties. i n the winter season the surface roughness terms (u,, and l) wcre shown to have a significant impact on u" when thc ice surface was the primary scattering mechanism. once the snow cover began to warm and water was available in a liquid phase. the ice surface bccame masked because of the decrease in microwave penetration depths. during this period the water volumc variablc dominated u", both from its impact on d. and due to its control ovcr the dielectric mismatch created at thc air/snow interfacc. d . g. barber. department of geography. university of manitoba. winnipeg, mb. r3t 2 n 2 canada; e . i;. ledrew, earth observations laboratory. department of geography, university of waterloo, waterloo. ontario. canada. n ' j k . p ~ ~ , t , ~ \ ~ 5 5 ' . introduction i n this research a series of electromagnetic inter action models are used to elaborate upon the role which geophysical properties play in defining microwave interaction with snow-covered sea ice. we focus on temporal sensitivity analysis, with the important caveat that spatial variation must be ascertained before seasonal evolution of micro wave scattering can be explored. based on the experience gained from simmspo and simms'91, the sensitivity analyses conducted are considered typical of the sar scattering seasons (livingstone et al. 1987): winter, early melt, melt onset, and advanced melt. the scattering of microwave energy over sea ice is a function of the dielectric properties, surface roughness, and volume inhomogeneities of the snow and sea ice. the relative scattering cross section (a") changes over time and space. spatial variability is largely a function of the geophysical properties which contribute to the volume di electrics, or surface roughness of the material. temporal variability is strongly controlled by the dielectric mismatch across the air-snow and snow ice interfaces. the principal variables are the relative phases of water (ice, liquid and vapour), crystal size, brine volume and the vertical and horizontal roughness point estimates of the sur face autocorrelation function. active microwave remote sensing consists of a sensor which generates and transmits (hence the term active) microwavelength energy towards a scattering surface over a range of incidence angles. this energy is scattered from the volume inhomogeneities and surface roughness charac teristics of the earth material. the synthetic aper ture radar (sar) is the most widely used form of active microwave remote sensing. common frequencies for orbital and aerial sar occur at the 5.3 ghz (c band) and 9.25 ghz ( x band) 36 d. g. barber & e. f. ledrew frequencies. polarizations on orbital, single fre quency sar sensors are typically hh or w. this means that the signal is both transmitted and received with either a horizontal (hh) or vertical (w) polarization. the scattering mechanics of a sar are a func tion of the sensor configuration, sensor-earth geometry, and dielectric properties of the material. scattering can be separated into surface and volume components. if there is a strong di electric mismatch at a particular interface then the surface scattering will dominate. the relative backscattering coefficient uo is a measure of the amount of returned power per unit area, measured at the sar antenna. the relative complex dielectric constant (1) is used to express the permittivity ( e ' ) and loss ( e n ) of the material relative to the frequency, polar ization and incidence angle of the microwave energy. e* = e' + j f (1) roughness can be approximated by the fraun haufer criterion (2). this provides an index of roughness for a given vertical and horizontal dimension as a function of the angle and fre quency of the incident microwave energy, fol lowing ulaby et al. (1986). a uh < 32 cos 8 a powerful tool for understanding the com plexities of the microwave scattering process, and thereby constrain sar algorithm development, is through the use of first order microwave scat tering models. the termfirst order is used because the models are able to handle only bulk volume attributes. the physics of the interactions are usually handled through radiative transfer (mie or rayleigh scattering), surface scattering the ories (of the kirchhoff type) and dielectric mix ture models, each of which require geophysical variables as inputs. this is a forward modeling approach, where the physical properties of the snow and sea ice are known, and the electromagnetic (em) inter actions are predicted. the use of forward modeling allows for an improved understanding of the scattering process through an analysis of individual geophysical variable contributions to the magnitude and seasonal evolution of u'. modeling also allows for interpolation of uo within a constrained range of geophysical observations acquired over a spaceltime continuum. the final attribute of the modeling process is a capability to extrapolate beyond the spatial and temporal sampling boundaries inherent in the surface data collection. geophysical properties of the snow and sea ice were collected over a series of spatial and temporal scales during the seasonal sea ice moni toring and modeling site (simms) experiment (barber et al. 1991; barber et al. 1992a). these data are used to evaluate the relative sensitivities of various geophysical properties known to affect microwave interaction with the seasonally vari able snow-covered sea ice volume. sensitivity analyses are conducted both for dielectric proper ties (i-e., dielectric mixture models) and for total relative scattering cross sections (ao). the objec tive is to investigate the magnitude and direction of change in the scattering cross sections as the water in liquid phase increases within the snow cover on landfast first-year sea ice. methods microwave scattering models the microwave scattering models implemented here separate the scattering process into an air snow interface, a snow volume, a snow-ice inter face and an ice volume. bulk properties are uti lized for each interface and volume. the relative complex dielectric constant is computed at each interface and as a bulk property of each volume. scattering is constrained to surface conditions meeting the assumptions of the kirchhoff physical and geometric optics models, and t o volume scattering conditions meeting the assumptions of a rayleigh scattering volume (ulaby et al. 1986). details of the model can be summarized into the general categories used in computation, namely: dielectric mixture models; surface scattering models; volume scattering models; and model integration. dielectric mixture models dielectric properties are important in microwave scattering because they define the electrical con ductivity of the material relative to the wavelength and polarization of the incident energy. this modeling synthetic aperture radar (sar) scattering 37 defines the amount of energy, and its refraction angle, for layers beneath the snow-air interface. the dielectric constant is expressed as the com plex sum of a real and imaginary part (1) where j is the square root of negative one. typically, dielectric mixing models are used to predict the complex dielectric constant of a heterogeneous material. a mixture model is required because both snow and sea ice are combinations of water (in liquid, vapour or ice phases), salt (as a solid or more importantly as brine) and air inclusions. to estimate the dielectric properties of sea ice it is important to consider the relative proportions of brine within the mixture and the proportion of salts within the brine. the salinity of the brine (sb) is also a function of the ice temperature (t). with increasing negative temperatures the proportion of salts within the brine mixture increases. this can be computed from 3 to 5 following assur (1960). sb = 1.725 18.756t 0.3964t2, 8.2 5 t i -2°c (3) (4) ( 5 ) sb = 57.041 9.9293 0.16204t2 0.002396t3, -22.9 5 t 5 -8.2"c sb = 242.94 1.5299t 0.0429t2, 36.8 i t i -22.9"c the brine volume (vb) is a function of tem perature and salinity (si) and is inversely pro portional to the strength of the ice. brine volume can be computed from salinity and temperature by (6 to 9), following frankenstein & garner ( 1967). 5 t 5 -2.06"c (7) vb = 1o-'s, (y2 1.189), 22.9 where: vb is brine volume in ppt. s is the ice salinity in ppt. t is temperature in "c. to complete the dielectric mixture model of sea ice, a measure of the size, shape and dis tribution of the brine and air inclusions is required. this is an important concept because of the geometry of the incident radiation. clearly there is considerable variation in these parameters within a natural ice surface. most workers have taken a pragmatic approach to the problem, par ticularly when the dielectric properties will be utilized in a second model (i-e., in microwave surface scattering). a common approach is to utilize linear approximations (10-13) of e' and e" based on empirical results of vant et al. (1978). &' = 3.05 + 7.2 vb/100, first-year ice; 4 ghz (10) first-year ice; 4 ghz (11) multiyear ice; 10 ghz (12) multiyear ice; 10 ghz (13) &" = 0.024 + 3.3 vb/looo, &' = 2.46 + 22.4 vb/looo, el' = 0.006 + 10.0 vb/looo, the polder-van santen/de loor model, which assumes spherical inclusions of brine, can be used to compute the dielectric constant of first year sea ice (14) and an approximate form for e' can be expressed as (15), following hoekstra & cap pillino 1971). where 5 is the relative permittivity of pure ice and vb is the volume fraction of brine. the dielectric loss of sea ice (16) has been computed based on a similar mixing model to (14) by hoekstra & cappillino (1971). &i. s i 21 v h &" b (16) where e s is the dielectric loss of brine, and vb is the brine volume. when considering the dielectric properties of the snow cover on sea ice it is important to con sider that the densities of brine and ice are 38 d . g . barber & e . f. ledrew different. this means that the brine volume com puted from (6 to 9) must be weighted by the ratio of brine and ice within the snow volume (17 and 18) where pi is the density of pure ice, p,, and ph are the density of snow and brine. when free water becomes available within the snow pack the dielectric properties change con siderably. the relationships between &' and e" for wet and dry snow have been determined empiri cally. models for computation of e' and e" of wet snow relative to the values for dry snow, have been developed by tiuri et al. (1984) and are presented in (19 to 22). &iry = 1 + 1.7pdry + o.7p2dry w e t = z e t 4 r y (19) (20) (21) (22) = ~l(0.1 w, + 0.8 w, + 0.8 w<) = ~ l ( 0 . 1 w, + 0.8 wt) where: e' is the dielectric permittivity e" is the dielectric loss w, is the volume fraction of water a denotes a change in a particular par ameter through use of these dielectric mixture models it is possible to compute the penetration depth (6p) of various frequencies of electromagnetic energy into a seasonally dynamic snow-covered sea ice volume (23), following drinkwater (1989). 11 2 112 6 +[(i+(;)) 4n (23) where ,i is the sar wavelength in meters, e' and e" are the dielectric permittivity and loss given a particular water volume within the snow pack. volume scattering models in modeling the relative scattering cross section (a") from a snow-covered sea ice volume it is important to specify the contribution of volume scattering (a!) from the snow cover. a commonly used volume scattering model, uses a rayleigh cloud analogy radiative transfer equation. this physical/empirical hybrid assumes that the air bubbles are spherical, distributed uniformly throughout the ice volume, and are of equal size. the backscattering coefficient attributable to the volume scattering cross section (a!) is expressed as (24). a,cos e 1 a:(e)=2k, (1-(exp(kedsec(0)))2 where the term u, is a volume scattering coef ficient based on a presumed dielectric mixing model and the presence of known ice scattering and water scattering radii in an air background dielectric. the average scattering is considered an independent variable which is a function of the average scattering cross section from a particular scattering centre (ah) where the subscripts i and s refer to ice and snow respectively. the variable k, is defined as (25) and d is the thickness of the scattering volume (i.e., snow thickness). 1 (25) k = 6, the number density (n) is multiplied by the scattering contributions from each in specifying the volume scattering coefficient (uv). com putation of the average volume scattering coef ficient (26), the number density (27), and the ice and snow scattering components (28 and 29) are: n = 3v/4nr3 (27) where v is the volume fraction of either water or ice in the snow and r is the radius of the average particle size. the contribution of the ice and water as point scatterers is summarized within the vol ume scattering term approximated from the com bination of ice and water radii scattering centres. where k is defined as a complex term which relates the dielectric properties of the scattering centre (either snow particle or water particle) within the air background dielectric (29). (e: + je7) ( e a + j&) (4 + j.$) + ~ ( e a + je)k) k = modeling synthetic aperture radar (sa r ) scattering 39 where k is computed for either subscript i (as shown in (29)) or for w when computing k for the water scattering coefficient. the subscript a refers to the complex properties of the air back ground dielectric. surface scattering models a series of models have been found to have reasonably precise application in the field of microwave scattering from snow-covered sea ice (ulaby et al. 1986; kim et al. 1984; drinkwater 1989; livingstone & drinkwater 1991). the scat tering physics are predicted within the kirchhoff scattering models. two approximations to the kirchhoff integral are used here. for an expo nentially decaying angular dependence, charac teristic of a relatively smooth sea ice or snow surface, the kirchhoff model with a scalar approximation (physical optics formulation) is appropriate, following ulaby et al. (1986). for surfaces displaying a slowing varying angular dependence, characteristic of a relatively rough sea ice or snow surface, the kirchhoff model with a stationary phase approximation (geometric optics formulation) is used, again following ulaby et al. (1986). physical optics formulation. for smooth unde formed ice surfaces with rms slopes (s) less than 0.25 radians, the surface scattering model pro posed by eom 1982 (31) using an exponential correlation function (following drinkwater 1989; kim et al. 1985) provides reasonable agreement with scatterometer results (kim 1984). the exponential correlation function can be expressed as (30). p ( p ) = exp -i 3 the kirchhoff surface scattering model for either snow surface or ice surface scattering can be described as (30) u:( e) = 21 rhh 1 c o s ~ e exp( -4kauz cosz e) . 5 (4k;d cos2 8)” (k;n/l) n = l n! . (4ki sin2 8 + nz/12)3/2 where parameters of the model related to a hori the wavenumber in air, expressed as a function of the wavelength in metres (32). ko = 2n/a (32) the fresnel reflection coefficient (33) is a meas ure of the amount of radiation which is reflected at the interface between adjacent mediums. it is computed as a complex ratio of the dielectric properties of the two materials creating the interface (i.e., air-snow or snow-ice). g2 x cos e ~ c o s 0 1 (33) r h h = 52 x cos 8 + 5, x cos 8’ where stants of the air and snow (34 and 35). and ez are the complex dielectric con (35) 1 , for inaterial (2 (snow) 5 2 = z q z r the change in the incidence angle due to the fresnel reflection coefficient is expressed as (36). where the complex quantities with subscripts a and s are for air and snow. with the snow complex dielectric quantities coming from the dielectric mixing formulae described in (19) to (22) above. in the case of a vertically incident and reflected electromagnetic field the fresnel reflection coef ficient is expressed as (37): (37) the roughness of the snow (or ice) surface can be described as the rms height, or vertical roughness (u,,) and the correlation length (l), or horizontal roughness. the ratio of the vertical to horizontal roughness components of a ran domly rough field provides a measure of the rms slope. the greater the rms slope the rougher the surface. geometric optics formulation. for rough ice surfaces with rms slopes greater than 0.25 radians the surface scattering model proposed by eom 1982 (39), using a gaussian correlation function zontally incident and reflected field are: (38) is appropriate. the operational assumptions 40 d . g . barber & e . f. ledrew which are different than the scalar analytical solu tion are: ko s > 2 and s > 1/3 (following ulaby et al. 1986 and drinkwater 1989). p(x) = exp( -x2/12) (38) r(0) exp( tan2 6/2m2) 2m2 c o s ~ 6 u:(e) = (39) where: r(0) = the fresnel reflection coefficient at normal incidence. m = vt(?) the implementation of these two surface scat tering models was done using a spreadsheet pro gramming language on a mackintosh iici microcomputer. the validity conditions (table 1) were tested with each computation of the back scattering coefficient and the appropriate model was automatically selected. model integration the combined model results for a snow and sea ice volume can be expressed as the component due to snow surface scattering (a:; physical optics or geometric optics formulation) and that due to snow volume scattering (a!). note that a: refers to surface scattering for either the snow or sea ice surface. the same notation is used because, under typical conditions, one or the other surface dominates a”, not both. for computation of uo, a common approach is to sum the contributions of each scattering medium, weighted by the transmissivity coef ficient. this means that the volume scattering term would be weighted by the transmission coef ficient across the air-snow interface (y%), which is related to the fresnel reflection coefficient according to [40] and the total scattering from a seasonally evolving snow-covered sea ice surface table i . validity conditions for the geometric optics and physi cal optics approximations to the kirchhoff surface scattering integral. physical optics model geometric optics model ~~ v2 t a& < 0.25 (zkocos o)* > 10 k l > 6 and lz > 2.76d ~~ ~~ where: k = h/i; a, = vertical roughness; l = horizontal roughness or correlation length. would be (41). under typical seasonal transition conditions the transmissivity across the air-snow interface (yj is sufficiently small that ysi (i.e., snow-ice) is effectively zero, meaning that the contribution of the ice surface scattering 00 to uo, can be ignored. ya = (1 i ~ h h i ) u l t a d e ) = 4 + w 6 ) * 4 ” ( @ ’ ) (40) (41) where ds and refer to the scattering con tributions from the snow surface and snow volume. analysis design modeling microwave scattering a series of sensitivity analyses are conducted t o elaborate upon the effect of ‘dielectric proper ties’, ‘geophysical properties’, and ‘seasonal evolution’ of the snow-covered sea ice, on micro wave scattering. dielectric properties. dielectric properties are assessed by using the dielectric mixture models described above. the relative effects of e’ and i‘ are assessed for a typical range and magnitude of the geophysical properties which give rise t o changes in the snow and sea ice geophysical properties. the dielectric models are initialized with geophysical variables measured during simms’90 and simms’91. the dielectric proper ties of sea ice and of the snow cover are important in specifying the total relative scattering cross section from this surface. winter conditions are driven primarily by sea ice dielectrics and the seasonal evolution by the snow volume dielec trics. geophysical properties. geophysical properties are assessed by conducting two sets of sensitivity analyses, designed to determine the relative sig nificance of particular geophysical properties within the winter season and within the tran sitional seasons of early melt, melt onset, and advanced melt. these sensitivity analyses are used to evaluate a particular geophysical variable range while holding all other model parameters constant. the winter and seasonal transition sensitivity analyses are conducted at 5.3 and 9.25 ghz fre quencies at hh polarization. these frequencies were selected because 5.3 ghz is available from modeling synthetic aperture radar (sar) scattering 41 the earth resource satellite (ers-1) and 9.25 ghz is available on the sea ice and terrain assessment radar (star-2). the frequencies are evaluated over a 10" to 80" incidence angle range, at 2.5" increments, using geophysical data acquired during simmspo and simms'91. two groups (5.3 and 9.25 ghz) are computed, each with 5 sets of 7 trials (tables 2 and 3). each set consists of the analysis of one parameter, tested at five levels, while the other concomitant variables are held constant. the sensitivity analy ses are considered valid for typical winter season conditions and over the range, melt onset to advance melt. winter is required as a tie point from which to address the seasonal evolution of u". the physical properties evaluated in the win ter season sensitivity trials are limited to rms height and correlation length because of their significant effect on microwave scattering. the sensor, sensor-earth geometry, and geo physical properties used in the seasonal sensitivity analyses include: microwave frequency (fi) , polarization (pol), water volume of the snow (wj, snow density (ps), rms height (u,,), cor relation length (l), snow depth (ds), and the radius of ice crystals in the snow (ri) and water inclusions within the snow (r,,,). the initial con ditions and the range of variables tested within each set are described in table 2 and table 3. when interpreting the range and magnitude of uo it is important t o note that the two surface scattering models have been implemented so that the parameters being tested in the model auto matically determine which model is used. since the geometric and the physical optics models are approximations of the kirchhoff integral there will be imprecisions within the range of parameters where the validity conditions flip from one model t o the other. the validity conditions used here are expressed in table 1. seasonal evolution. the seasonal evolution of at' was modeled using data from simmspl over the period julian day 138 t o 163. variables used in the modeling were extracted as averages from the snow pit samples acquired from all first year table2. sensitivity initialization parameters used in modeling trials of a combined snow and sea ice microwave scattering condition. f, pol w" a oh l d, r, rw ghz %/lo0 kg.m-' metres metres metres metres metres 5.3 h h variable 5.3 h h 0.05 5.3 h h 0.05 5.3 h h 0.05 5.3 hh 0.05 5.3 h h 0.05 5.3 h h 0.05 9.25 hh variable 9.25 h h 0.05 9.25 h h 0.05 9.25 h h 0.05 9.25 h h 0.05 9.25 h h 0.05 9.25 h h 0.05 300 variable 300 300 300 300 300 300 variable 300 300 300 300 300 0.01 0.01 variable 0.01 0.01 0.01 0.01 0.01 0.01 variable 0.01 0.01 0.01 0.01 0.08 0.08 0.08 variable 0.08 0.08 0.08 0.08 0.08 0.08 variable 0.08 0.08 0.08 0.3 0.3 0.3 0.3 variable 0.3 0.3 0.3 0.3 0.3 0.3 variable 0.3 0.3 0.001 0.001 0.001 0.001 0.001 variable 0.001 0.001 0.001 0.001 0.001 0.001 variable 0.001 o.oooo25 o.oooo25 o.oooo25 o.oooo25 o.oooo25 0.000025 variable 0.0025 o.oooo2.5 0.000025 0.0025 0.000025 0.000025 variable table 3. variable conditions tested in the sensitivity analyses (table 2). the term "variable" in table 2 is represented by the range of conditions specified by the 5 sets presented. set w" h ah l ds r, r w %/lo0 gm-cm-' metres metres metres metres metres 1 0.001 0.1 0.001 0.06 0.1 0.0001 0.000005 2 0.0325 0.2 0.005 0.105 0.325 0.001325 0.000129 3 0.055 0.3 0.009 0.150 0.55 0.00255 0.000252 4 0.075 0.4 0.013 0.195 0.75 0.003775 0.000376 5 0.01 0.5 0.017 0.24 1.0 0.005 0.0005 42 d . g . barber & e . f. ledrew ice sites. the variables w,, ps, and ri were extracted as a time sequence, with interpolation across adjacent points to account for missing data. water volumes were highly variable over the diurnal cycle. daily averages were computed from data collected between the hours of approxi mately 1000 and 1800 hrs (local time). the water volumes were interpolated between days where wv measurements were missing. after julian day 156, the snow pack began to drain as the transition between pendular and funicular regimes was re alized. to approximate the bulk snow pack water properties the water volume was extrapolated, based on the trend observed between julian days 149 and 156, to day 163. the variables o h , l, d, and r, were fixed at the average value observed between julian days 138 and 163. frequency was evaluated at 5.3 and 9.25 ghz with horizontal send and receive (hh) polarization. incidence angles were computed for 20°, 30" and 40". these approximate the frequency and polarization of many operational sar sen sors and the orbital incidence angle ranges which are, or will be, available on ers-1 and rad arsat. the seasonal evolution of a" illustrates the magnitude of u" which can be expected from a seasonal evolution of the geophysical properties which give rise to microwave scattering. the val ues presented are daily averages, and as such, are considered appropriate only as an indicator of seasonal evolution. diurnal variation in w, and ri within the snow can cause dramatic shifts in the microwave scattering response from the snow covered sea ice surface (barber et al. 1992b). results and discussion dielectric properties in the context of microwave scattering, winter sea ice can be considered as a three component medium: ice crystals, air pockets, and brine. each component has a very different complex dielectric constant at microwave frequencies and exists in different characteristic sizes, shapes, volumes and surface distributions (livingstone 1989). since the scale sizes of the constituents (-mm to -cm) are within the range of wavelengths found at microwave frequencies, we can expect charac teristic signatures based on the scattering from the constituent combinations. in general the average relative complex dielectric constant of sea ice is a function of these constituent parts, relative to the look direction of the electric field (ulaby et al. 1986). the brine inclusions exercise the strongest control on the average complex dielectric constant of sea ice because the permittivity is much higher ( e ' = -70) than that of pure ice ( e ' = 3.15; johannsson & askne 1987; winebrenner 1989). the relative volume of brine in sea ice has been shown to be a function of temperature and salinity, and is inversely proportional to the strength of the ice. figs. 1 and 3 show the effect of varying temperatures and salinities on the per mittivity and loss of first-year and multi-year sea ice at 4 and 10ghz frequencies. these graphs are computed from empirical dielectric models (10 to 12), following vant et al. (1978). in general, the permittivity of sea ice decreases with decreasing temperature and increases with increasing salinity (figs. 1 and 2). the permittivity of multi-year ice would be lower than that of first year ice at the same frequency. the dielectric loss ( e " ) of sea ice increases with increasing salinity and temperature (fig. 3). a dielectrically "lossy" material is one with a high e " . higher values of e" result in lower microwave penetration depths into the ice surface and therefore a larger con tribution of surface scattering to a". multi-year ice has a lower value than first-year ice because of the lower salinity and density of the upper layer. in the context of microwave scattering, the snow cover on sea ice can be considered as a combination of snow crystals and water inclusions within an air background. snow cover on sea ice is different than snow found on terrestrial surfaces in two aspects, each of which are important to sar scattering from sea ice. first, when new ice forms, a hoar layer develops. this hoar frost is highly saline and forms a snow cover in the fall without mass inputs from blowing or falling snow (drinkwater & crocker 1988). since this hoar layer (hd) is high in salinity and water content it affects both thermal and vapour transfers between the ice and atmosphere. second, as snowfall is added over this hoar layer there is a transfer of brine from the hoar layer into the overlaying snow through both mechanical mixing and as a result of capillary suction from the snow cover. typical salinities of snow-covered first-year ice show that the brine concentrations are highest at the bottom of the snowpack and decrease towards the surface. for thin snow covers on newly formed modeling synthetic aperture radar (sar) scattering 43 si i 7 +\multiyear ice i l°chzl i i 2.1 : : : : : : : : j -2 -4 -6 -8 -10 -12 -14 -16 -18 -20 temperature (“c) fig. i. permittivity as a function of ice typc. frequency and tempcraturc. 3.4 we 3 .. 2.8 2.6 2.4. l 2.2 1 2 4 ; ; : : : : : : i 5 6 7 8 9 10 11 12 13 14 salinity (ppt) fig. 2 . permittivity as a function of ice type. frequency and salinity. 0.6 7 5 6 7 8 9 10 11 12 13 14 salinity (ppt) fig. 3. dielectric loss as a function of temperature and salinity. ice, salinities can be in excess of 40ppt and for thicker snow covers over thicker ice, salinities have been found in excess of 20ppt (crocker 1984). the winter snow cover on sea ice is a three component medium, containing various pro portions of air, brine and ice. as with any het erogeneous material, the average relative complex dielectric constant is due to the dielectric constants of each of the constituent parts. the dielectric permittivity of dry snow ( e ’ ) is approxi mately 1.18 at a density of o . l g m . ~ m ~ and increases to 2.03 at a density of o s g m ~ m ~ . when the wavelengths are larger than the snow crystals (which is generally the case) e’ is inde pendent of frequency. dielectric loss ( e ” ) of dry snow is frequency dependent and has been measured between a range of 2 x for frequencies from 5 to 40 ghz (matzler 1987; colbeck 1981). the seasonal transition snow cover consists of much different relative proportions of the three water phases. the increase in the amount of water, in a liquid phase plays an important role in specifying the permittivity and loss of the snow cover. the effect of water volumes between 0.1 and 10 percent are shown to be density and fre quency dependent. permittivity of wet snow increases both with increasing water content and with increasing snow density (fig. 4). the di electric loss of a wet snow cover is density inde pendent and water volume dependent (fig. 5). as water volume increases between 0.1 and 10 percent e” increases from 0.004 to 0.667. note that the e” of dry snow is approximately 0.0008 (tiuri et al. 1984). a 5.3 ghz frequency was used in computing e’ and e” in figs. 4 and 5. when the electromagnetic frequencies are con sidered, both e’ and e“ are shown to be frequency and water volume dependent. permittivity increases with decreasing frequency or conversely, longer wavelengths result in larger permittivity (fig. 6). the relationship between e” and frequency illustrates an important point regarding the debye relaxation spectrum for water. as the water volume increases there is an increase in e” (fig. 7). the rate of increase appears to be variable amongst the 4.0 to 12.0 ghz frequencies with maximum e” occurring at about the 10 ghz frequency (fig. 7). a more detailed view of this relationship shows that e“ peaks at about the 1 0 g h z frequency (fig. 8). this corresponds to the relaxation frequency of water based on the debye spectrum (matzler 1987). the final condition, of importance in dielectric modeling, is the effect of snow cover on the relationship between atmospheric and snow-ice interface temperatures. from snow depth, ice to 1 x modeling synthetic aperture radar (sar) scattering 45 0 -2 -ta=-5oc _--_------ cta = 10°c ___.----#c- -4 -c -6 v / f l _. ___-. ta = -20°c # .i---..5 i-8 ...' -10 -* * -12 : sea ice = 100 cm 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 3 2.5 .. salinity = loppt sea ice = loocm 2 , frequency = 4ghz ".l i wv = 5.0 40 1 0.1 .; 0. " ' : ' * ' : " ' : " ' 2.0 6.0 10.0 14.0 18.0 frequency (ghz) fig. 8. diclectric loss ( e " ) for 5.0 and 8.0% water by volume. peak e" occurs at approximately 10ghz frequency for both water volume conditions. fig. 7. dielectric loss ( e " ) as a function of water volume and microwave frequency. models used in computing these results are described in equations (19) t o (22). thickness, and atmospheric temperature, ice sur face temperatures can be estimated using a one dimensional thermodynamic model (nakawo & sinha 1981). the relationship between various snow depths over a 1 m thick first-year ice surface is presented in fig. 9. it is apparent from this figure that a snow cover can make a considerable difference on the snow-ice interface temperature (ts,i) depending on the snow depth (sd) and ambi ent temperatures (ta). the snow cover effects the ice surface tem perature, which effects the brine volume of sea ice, which in-turn effects the dielectric constant. the volume of brine can then be used in com putation of the average complex dielectric con stant of sea ice under winter conditions (fig. 10). when the effect of snow cover on the surface fig. 9. temperature at the ice surface as a function of snow depth and air temperaturc. fig. 10. change in permittivity ( e ' ) of the dielectric constant as a function of snow cover on a 100 cm thick ice sheet. 46 d . g . barber & e . f. ledrew temperature is considered, it is possible to com pute e' as a function of snow depth, ice thickness and microwave frequency using equations (10 to 13) (vant et al. 1978). the slope of each line in fig. 10 provides a measure of the sensitivity of snow cover on the dielectric properties of the sea ice surface. as expected, the higher the atmospheric tempera ture, the larger the magnitude change in el. the largest increase is between no snow cover and 10 cm. this is because the thermal insulation of even a thin snow cover is significant. the relationship between el' and snow cover is plotted in fig. 11. the same general relationship as e' is evident. there is a larger increase between no snow cover and a locm cover. there is also a larger difference between -10°c and -5"c, relative to -10°c and -2o"c, atmospheric tem peratures. in summary, both el and e" decrease as fre quency increases. although this is a complex relationship, the major factor appears to be the interrelationships between brine conductivity and the relaxation mechanism of water with increas ing temperature. although the volume of brine is much smaller than the volume of ice there is still a disproportionate influence because of the dielectric mismatch between brine (70-j20) and ice (3.15-jo.01); vant et al. 1978; tiuri et al. 1984). snow cover provides the most interesting changes in cr" when free water becomes available in the snow pack. as the water content increases the penetration depth of microwaves into the snow pack decreases. by linking the microwave frequency (a), the permittivity of dry snow (19), the change in el due to wetness (ae'wet; (21)), and the dielectric loss of wet snow (22), a general model (23) can be used to compute penetration fig. 12 shows the impact of very small quantities of water on the penetration depths at a variety of snow densities. as the penetration depth decreases, the average scattering from the snow covered sea ice contains an increasing con tribution from the snow volume and snow surface geometry. density plays only a minor role in specifying the penetration depths at 5.3 ghz into the snow cover. fig. 13 shows the effect of varying frequency, at a constant density for sp. frequency appears to contribute somewhat to the variability in microwave penetration depths. note that within the range 0.001 to 0.01 water depth (&i. by volume (0.1 to 1.0% wv), the penetration depths at all snow densities between 0.1 and 0.5 g m ~ c m ~ dropped from 2.493 m to 0.239 m. this constitutes an order of magnitude drop in penetration depths, over a range of snow wetness conditions which can occur very rapidly during the seasonal transition from winter to melt onset. these penetration curves represent a minimum estimate since the scattering losses are assumed negligible in this simple model. this is an impor tant caveat since at such high water volumes there will undoubtedly be development of scattering mechanisms within the snow (i.e., ice lenses, layers, polycrystalline snow aggregates, etc.). the dramatic impact of small quantities of water, in liquid phase, reflect the conditions examined with the dielectric mixture models. the relaxation spectrum of water results in a minimum penetration depth at about the 10 ghz region (fig. 14). when the snow wetness reaches about 1 percent water by volume, the snow cover dom inates the scattering return since typical snow thicknesses exceed the 24 cm estimated by modeling sp. this means that the focus for sar scattering over the transitional periods from win ter to summer should focus principally on the snow volume dielectric and scattering mech anisms. geophysical properties in the winter season the vertical component of the surface roughness (q,) is shown to have con siderable influence on the scattering return at both c band (5.3 ghz) and x band (9.25 ghz) frequencies (fig. 15). the models were initialized with a correlation height of 0.08 m, an ice salinity of 7ppt, an ice surface temperature of -2o"c, and dielectric properties specified by (15) and (16). given these conditions the rms roughness heights of 0.001, 0.005, 0.009, 0.013, and 0.017 illustrate increasing scales of ice surface rough ness. the slow angular fall off in a" at the rms height of 0.001 is typical of the kirchhoff physical optics model for scattering from a loss less first year ice surface. the large increase in scattering between the 0.001 and 0.009 level illustrates the importance of surface roughness to sar scat tering. this range represents an approximate 12 db change in scattering, attributable to a minor change in surface roughness from 1 mm to 5 mm rms height. equivalent changes in surface roughness between 0.005 m to 0.13 metres show modeling synthetic aperture radar (sa r ) scattering 47 0.8 , 1 0.7 0.6 0.5 tu 0.4 0.3 0.2 0. i 0 4 i 0 10 20 30 40 50 snow depth (sd) in cm. fig. /i. change in diclcctric loss ( f " ) as a function of snow cover on a ioocm thick ice shcct. 1 h e v 1 !2 0.01 water volume (%/loo) fig. 12. relationship bctwcen microwave penetration depth (6p) and volume fraction of water (w,) at snow densities ranging from 0.1 to osgm.cm-' at a frequency of 5.3 ghz. that roughness becomes less important as the rms height increases (fig. 15). the distinct difference in the 0.017m rms height curve is a function of both the mechanics of the modeling process and significance sensor surface roughness geometry. at an rms height of 0.017 m the geometric optics model is more appropriate for specifying the incidence angle dependence of (to. the dramatic shape difference is a result of the fact that the physical and geo metric optics approximations are not a continuum, but rather two distinct approxi mations to particular geometrical conditions. the 10 +-h ! , : , : , ! .a ! , : ,! , ! , ! , : , : , : , ! , : , : rhy h € 1 s 8" f 6 0.1 '0 € a 12.0gh.z 3 snow density 0.3 nm.cm-3 t 6.0 ghz 8.0 ghz 10.0 ghz t water volume (%/loo) fig. 13. relationship between microwave penetration depth (6p) and volume fraction of water (wv) at frequencies ranging from 4 to 12 ghz and a snow density of 0.3 gmacm-'. 1 snow density = 0.3 g m a n 3 e 0.1 b 6 $: '0 u g 0.01 u w v = 5.0% 0.001 i.....,.] 2.0 6.0 10.0 14.0 18.0 microwave frequency (ghz) fig. 14. penetration depth (6p) for 5.0 and 8.0% water by volume. minimum 6p occurs at approximately 1 0 g h z fre qucncy for both water volume conditions. shape of the curve largely reflects the geometry of the model (i.e., slowly varying angular depen dence to surface roughness using a gaussian cor relation function). the rapid decrease after about 40" also illustrates that the roughness between 10 and 40" is detected by the sensor but at larger incidence angles, the angular dependence is such that the energy is scattered coherently in the specular direction. the horizontal component of the surface rough ness (l) is shown to have a minor (compared with the rms height) influence on the scattering return, during winter conditions, at both 5.3 and 48 d . g . barber & e . f. ledrew p b s % r % p s r x 3 b % p ~ incidence angle (5.3 ghz) incidence angle (9.25 ghr) 5 0 -5 -10 -15 -20 -25 8 -30 90 -35 -40 -45 -50 -60 -65 -55 hwironrolrovakvu horironlal roqhnur incidence angle (5.3 ghz) incidence angle (9.25 ghz) incidence angle (5.3 ghz) incidence angle (9.25ghz) a 8 d 3 z s i ? ~ 8 4 3 s s p s incidence angle (5.3 ghz) incidence angle (9.25 ghz) fig. 15. sensitivities of the ice sur face rms height (uh) variable at 5 . 3 and 9.25 ghz frequencies over the incidence angle range 10 to 80 deg rees. fig. 16. sensitivities of the ice sur face roughness correlation length (l) variable at 5.3 and 9.25gi-h frequencies over the incidence angle range 10 to 80 degrees. fig. 17. sensitivities of the water volume (w,) variable at 5.3 and 9.25 ghz frequencies over the inci dence angle range 10 to 80 degrees. initialization conditions of concomitant variables are specified in table 2. fig. 18. sensitivities of the snow density (p,) variable at 5.3 and 9.25 ghz frequencies over the inci dence angle range 10 to 80 degrees. initialization conditions of concomitant variables are specified in table 2. modeling synthetic aperture radar (sar) scattering 49 9.25 ghz frequencies (fig. 16). the models were initialized with an rms height of 0.01 m, an ice salinity of 7 p p t , an ice surface temperature of -2o"c, and dielectric properties specified by (15) and (16). given these conditions the rms rough ness heights of 0.60, 0.105, 0.150, 0.195 and 0.240 m depict decreasing scales of ice surface roughness (fig. 16). the slow angular decrease in uo at all levels of the correlation length variable indicates that the physical optics conditions were met with all the parameters of this sensitivity analysis. the general decrease in the scattering returns through the range of correlation lengths indicates that between 6 cm and 24 cm, given that all the other parameters are held constant, we can expect a maximum difference in uo of about 5db. the inflection points, where the relative scattering reverses, at about 15" and 25" at 5.3 and 9.25 ghz respectively, illustrate the relative nature of the term 'roughness'. at the shallower incidence angles the effect of surface roughness can actually reverse the magnitude of uo, relative to other incidence angles (note 0.06111 curve in fig. 16) curve at 9.25 ghz on either side of the 25" inci dence angle. the rms height (uh) and correlation length (l) of a winter season ice cover are typical of the surface scattering one can expect from first year ice. the magnitude of uo provides a measure of the scattering for a first year ice surface roughness using a range of values typical of the simms study area for winter conditions (i.e., typically january to april). in the transitional seasons of early melt, melt onset and advance melt water volume (w,) within the snow pack is shown to have a significant impact on the total relative scattering cross section (ao). at 5.3ghz an increase in water volume (w,) from 0.1 to 10 percent can create a maximum difference in scattering of about 7 d b (fig. 17). note that the relative effect of w, is highly skewed to the smaller values (i.e., 0.001). this means that small water volumes are more important than larger ones and that an effect can occur with water volumes as low as 0.1% water by volume. at 9.25 ghz a w, of 0.1% produces a much higher uo because the shorter wavelengths are more sen sitive to the presence of small water volumes (fig. 17). we could expect a maximum difference of 11 db between 0.1 and 10.0% water by volume at 9.25 ghz. it is interesting to note that at 5.3 ghz a w, of 0.1% would provide a lower scattering return than at a w, of 3% for incident angles between 10 and 30%. after this incidence angle there is a transition period where the low w, increases the uo relative t o all the higher water volumes. this is a function of the relative contributions of sur face and volume scattering t o the specification of uo. as the incidence angles increase, the trans mission coefficient ( v 2 ) decreases. this means that the volume term becomes less important, relative to the surface term (41), at larger inci dence angles. since the larger water volumes have smaller volume scattering terms, the combined scattering continues to decrease at the same rate as at smaller incidence angles (fig. 17). this effect is evident in the shorter wavelength (9.25 ghz) model, but the impact of a small w, is exacerbated because the shorter wavelength is more sensitive to the surface roughness par ameters (table 2) used in the initialization of this sensitivity trial. also note that the uo drops when w, is increased from 0.001 to 0.0325 (%/loo). with further increases in w, the uo increases, within the incidence angle ranges 10" t o 60". beyond this incidence angle range the relation ship reverts t o a decrease in uo with increasing w,. this complex relationship is a result of the dual role w, plays in increasing both ut and uf the former being virtually angular independent and the later highly angular dependent (fig. 17). snow density ( p s ) also plays an important role in determining the microwave scattering at c and x bands (fig. 18). at 5.3 g h z an increase in p s from 0.1 to 0.5 g m ~ m ~ can create a maximum difference in scattering of about 5 db. note that the relative effect of ps is approximately a linear increase in uo over all incidence angles, as the snow density increases. this increase is due to larger values of both the u: and ut components of a". the 4 is increased because of the effect of snow density on the dielectric properties of the snow volume. the ut is increased because of the enhance scattering from the volume inhom ogeneities and the increased dielectric properties attributable to the ps variable (fig. 18). at 9.25 ghz an increase in snow density ( p s ) from 0.1 t o 0.5 g m ~ m ~ can create a maximum difference in scattering of about 8 d b . as with the 5.3 ghz case, an increase in uo occurs as the density increases. the larger range of uo is due to the larger volume scattering term at 9.25 rela tive to 5.3 ghz (fig. 18). the smaller angular drop off at the 9.25 ghz frequency is a function 50 d . g . barber & e . f. ledrew vmable: vorricol incidence angle (5.3 ghz) incidence angle (9.25 ghz) fig. 19. sensitivities of the snow surface rms height ((i,,) variable at 5.3 and 9.25 ghz frequencies over the incidence angle range 10 to 80 degrees. initialization conditions of concomitant variables are specified in table 2. fig. 20. scnsitivitics of the snow surface correlation length (l) vari variable: horironrd roughmss able at 5.3 and 9.25ghz fre units: mcrrrs qucncics ovcr thc incidencc angle range 10toxodegrees. initialization 2 8 g 9 51 $ i? g 8 g 3 g 8 p 3 conditionsofconcclmitant variables incidence angle (9.25 ghz) are specified in table 2. incidence angle (5.3 ghz) 0 -5 -10 -1s -20 0 -30 3. -2s -3s -40 -4s f vuiable: snow depth -50 uniu: vmablc: s m depth units: mdres of the surface roughness term in specification of a" (i.e., the surface appears rougher to the x band radar). vertical roughness or rms height (uh) is an important parameter in specifying the relative scattering return from the snow-covered sea ice (fig. 19). as a general principal, the presence of water volume in the snow pack means that surface fig. 21. scnsitivities of thc snow dcpth (d,) variable at 5.3 and 9.25 ghz frequencies ovcr the inci dence angle range 10 to 20 degrees. initialization conditions of concomitant variables are specified in tdbk 2. roughness of the snow becomes important. when the snow pack is dry, the fresnel reflection coef ficient (r) is near zero (both at the air/snow and snow/ice interfaces), which means that most of the incident energy is transmitted across these interfaces and interacts either with the volume inhomogeneities or with the surface roughness of the sea ice. modeling synthetic aperture radar ( s a r ) scattering 51 at 5.3 ghz an increase in (jh from 1 mm to 17 mm can create a difference in a" of more than 30db (fig. 19). note that the relative effect of oh follows the same basic pattern for roughness heights of from 0.001 to 0.013 m. the 0.017 m height reflects both an artifact of the modeling process and a transition period where roughness dramatically impacts the scattering process. for the conditions tested, the 0.017 m parameters were most appropriately modeled with the geo metric optics formulation (39). this model uses a gaussian correlation function which results in a slow angular drop in u" up to an incidence angle where the surface no longer appears rough (fig. 19). the inflection point in the curve at u" = -35db at an angle of 57" is caused when uo reaches the volume scattering floor, specified by the initialization parameters used in these trials. at 9.25ghz an increase in rms height (oh) from 0.001 to 0.017m can create a maximum difference in scattering of about 25 db (fig. 19). as with the 5.3 ghz case, an increase in occurs as increases. note that an increase in (7" occurs for the 0.013m trial from 10 to 40" incidence angles (fig. 19). this appears to be a continuation of the trend evident at the 10 to 15" incidence angles at 5.3 ghz where the rougher surface actu ally tend to show smaller u" values. correlation length (l) or the horizontal com ponent of the surface roughness is important in surface scattering because it is a component of the roughness statistics. at 5.3 ghz an increase in l from 6 to 24cm can create a maximum difference i n scattering of about 6 d b (fig. 20). as the correlation length increases uo decreases. this is because the roughness, observed by the microwave energy, decreases with increasing cor relation length and increasing incidence angle. note that the relative effect of the correlation length is approximately a curvalinear decrease in u'l over all incidence angles greater than 20". at 9.25 ghz an increase in correlation length from 6 to 24cm can create a maximum difference in scattering of about 4 d b (fig. 20). note that the inflection point, where the shorter correlation lengths create a relatively lower a'' occur at larger incidence angles (i.e., 15" at 5.3 ghz and 30" at 9.25 ghz). this is a function of the roughness relative to the sensor-sea ice geometry. when rms height and correlation length of the snow surface are both considered (figs. 19 and 20), the most significant aspect about roughness is that the relative magnitude of uo is a function of the roughness, relative to the incidence angle and frequency of the radiation. the reversal of a" at incidence angles below 30" in the 9.25 ghz case appears to be consistent between both the rms height and the correlation length. this is because the vertical and horizontal components of rough ness are a tradeoff. it is perhaps simpler t o con sider rms slopes ("m" in equation (39)) as an index of roughness. it is also important t o note that rms heights (uh) of snow and sea ice can be obtained with reasonable precision. correlation lengths (l) are much less precise because of dif ficulties in specifying a spatial interval over which to compute the summary statistic. the snow depth (dj variable would be a valu able parameter to invert from microwave scat tering because of its influence on energy and radiation balance parameters. at 5.3 ghz there is no significant separation of the five depth trials. this is because the slope of the scattering angular dependence is specified by the snow surface roughness and the volume scattering term is dri ven by the size distribution of volume inhom ogeneities within the snow. snow depth is sufficiently less important so that no detectable difference is observed (fig. 21). at 9.25 ghz the same conclusions may be drawn, with the notable exception that the slope of the curves is decreased over the 10" to 60" incidence range because of the impact of surface roughness at the shorter wavelength (fig. 21). further examination of this relationship shows that at lower values of w, the separation of d, increases, albeit marginally (fig. 22). of note is that the separation of snow depths is enhanced when two frequencies are compared. a maximum separation of 7 d b occurs between 5.3 and 9.25 ghz for both 0.1 m and 1.0 m snow depths at a water volume of 1% (fig. 22). separation of snow depth classes may be possible using water volume in combination with multifrequency data. the snow crystal radius (ri) variable shows considerable variation over the range of con ditions tested. at 5.3 ghz the difference in scat tering increases from a minimum of 2 d b at lo" to a maximum of 18 db at 80" incidence (fig. 23). the increase in a" with increasing snow crystal radius is caused by an increase in the scattering cross section of the ice crystal (%i) which creates an increase in the volume scattering coefficient at 9.25 ghz the snow crystal radius enhances the difference in scattering amongst the five trials (a!). 52 d. g. barber & e . f. ledrew 0, i 9.250hz i)i 0.1 m 9.73 0.1 m di -35 5.3 chi 1.0m di -50 "fl -55 p 8 8 7 1 g s 1 8 z s incidence angle fig. 22. relationship between snow depth (d,) at 0.1 and 1.0 m, and frequency at 5.3 and 9.25 ghz over the incidence angle range 10 to 80 degrees. initialization conditions of concomitant variables are consistent with those in fig. 21 (see table 2) with the exception of w, which was set t o 0.01. is a result of the general increase in the volume scattering at all crystal radii, from the shorter 9.25 ghz radiation. the scattering cross section of the ice crystals (abi) is an order of magnitude larger for the 9.25 relative t o the 5.3 ghz fre quency. water inclusion radius (r,) shows no dis cernible variation in ao over the two frequency groups tested. the difference in the slope of the 5.3 versus 9.25 ghz groups is a function of the surface roughness concomitant variable (fig. 24). the water inclusion radius (r,) and the snow crystal radius (ri) are used in specifying the vol ume scattering coefficient (av; (25)) which is then used in computation of the volume scattering cross section (at (24)). differences in the size of the inclusions appear to have no impact on the scattering trials computed here. this results from fig. 23. sensitivities of the snow crystal radius (r,) variable at 5.3 and 9.25 ghz frequencies over the incidence angle range 10 to 80 deg rees. initialization conditions of concomitant variables are specified in table 2. variable: ice crysdrndjw units: mans incidence angle (5.3 ghz) incidence angle (9.25 ghz) o.ooom)5 0.000129 o.wo152 fig. 24. sensitivities of the water inclusion radius (r,) variable at 5.3 and 9.25 ghz frequencies over the incidence angle range 10 to 80 deg rees. initialization conditions of 2 w g 3 g 8 e % 8 4 9 8 % concomitant variables are specified incidence angle (9.25 ghz) in table 2. vmiable: water lnclwim rdiw uniu: mc~rcs incidence angle (5.3 ghz) tested. there is a minimum difference in uo of 10 db at lo" and a maximum of 25 db at 80" incidence (fig. 23). the larger separation at the shallower incidence angles between c and x band the fact that the scattering coefficients for the water inclusions (ahw) were between 5 and 7 orders of magnitude smaller than the same coef ficient for the ice crystal radii (uhi). this resulted modeling synthetic aperture radar ( s a r ) scattering 53 in a much smaller volume scattering coefficient (u,) and therefore a smaller volume scattering cross section (a!). these sensitivity analyses have illustrated the relative importance of a set of geophysical vari ables in specification of uo. the results are con tingent upon the correct implementation of the electromagnetic (em) interaction physics within the surface and volume scattering models used here. as a forward model, the implementation of easily observable geophysical properties within the scattering models is an important prerequisite to understanding the mechanics of the interaction process, for development of invertable models, and for defining constraints within which synthetic aperture radar (sar) data may be interpreted. although the models used here have met with considerable success in measurement of uo over snow-covered sea ice, the results are considered significant as a relative, rather than absolute, measure of the seasonal evolution of uo. conclusions in this paper we have introduced the concept of an integrated microwave scattering model which is appropriate for modeling the total relative scat tering cross section (ao) from a variety of snow covered sea ice volumes. in previous work (liv ingstone & drinkwater 1991) this model correctly approximated the total scattering cross sections observed for conditions similar to those sampled during simms'90 and '91. although the model accounts for only first order heterogeneity of the volume, it would appear to reproduce the approximate magnitude and range of ao over the seasonally variable snow-covered sea ice volume. the sensitivity analyses were begun using di electric mixture models. results of these models were used to illustrate the concept that the di electric properties of snow and sea ice are highly dynamic and, as such, are critical in understanding the seasonal scattering mechanisms. winter sea ice dielectric properties were modeled and the 3 phase combinations of ice crystals, air pockets and brine were shown to have considerable influ ence on the permittivity ( e ' ) and loss ( e " ) of sea ice. the influence of a snow cover on dielectric properties of winter season sea ice was explored by using a one-dimensional thermodynamic model forwarded by nakawo & sinha (1981). the impact of a small snow thickness over sea ice was shown t o have a significant impact on the dielectric properties of first-year sea ice. the dielectric properties of a snow cover were explored using a series of dry and wet snow semi empirical models. the seasonal transition period from the winter sar scattering season to early melt was shown to signal the transition in di electric properties which caused the snow volume to become a major factor in the microwave scat tering process. the effect of water volume within the snow cover was shown to be snow density and microwave frequency dependent on both e' and in a relative sense the sensitivity of e" was larger than for e' for a given set of snow density, water volume and microwave frequency par ameters. the effect of the thermal insulation of a snow cover on sea ice was shown to be significant for both e' and e". higher atmospheric temperatures caused proportionally higher changes in the di electric properties of the sea ice at the base of the snow pack. a t the conclusion of this subsection it was shown that the microwave penetration depth was a function of the increase in e' and e " . this led to the conclusion that microwave scattering from a snow-covered sea ice volume would consist primarily of snow surface and snow volume con tributions to a'. each of which would result, to varying degrees, from changes in the volume dielectric and scattering cross sections of the material within the background dielectric. the next set of sensitivity analyses were com puted for the total relative scattering cross section (ao) using a range of sensor, sensor-earth geometry, and geophysical properties. the range and magnitude of these variables were selected to approximate the conditions observed during simms'90 and simms'91 for the transition from winter to advanced melt. in the winter season the surface roughness terms (oh and l) were shown to have a significant impact on ao when the ice surface was the primary scattering mechanism. small changes in the rms height (q,) and correlation length (l) created dramatic changes in ao. once the snow pack began to warm and water was available in a liquid or vapour phase, the ice surface became masked because of the decrease in microwave penetration depths. this masking of the ice surface was observed in uncalibrated sar data acquired dur ing simms'90 (barber et al. 1992b) within the melt onset season. during the transitional seasons (early melt, 54 d . g . barber & e. f. ledrew melt onset and advanced melt), it was concluded that the snow water volume (w,) variable was an important parameter in specifying uo, both from its impact on u: and due t o its control over the dielectric mismatch created at the air/snow interface. both snow density ( p j and the snow crystal radius (ri) were shown to play a significant role in specifying d. as ps and ri increased so did un. although the water inclusion radius (r,) variable did impact u!, the effect was masked by the much larger increase in the ri term. the significance of snow depth (d,) on u" was shown to be a subtle relationship between the frequency of the incident radiation and the incidence angle. it appeared from these analyses that a combined 5.3 and 9.25ghz frequency could be used to obtain d, from uo, in summary, it was shown that as w, increased there was a shift in significance towards the u! term of un from u:i (ice surface roughness). once the w, term, in combination with ri, and p s , were large enough to restrict the penetration depth to mm range then began to dominate over ut in the specification of un. this meant the oh and l of the snow surface became the important vari ables in defining the magnitude and range of a". acknowledgemenrs. many individuals bring their individual expertise to bear within the simms experiment. thanks to: t . papakyriakou, r. de abreu, s. redan, d. flett, m. shokr, m. manore. s. patcrson, j.-c. deguise, b. ramsay and k. lamothc. the simms program is undertaken with support from a variety of agencies including a centre of excellence grant from the province of ontario and an nserc (natural sciences and engineering research council) operating grant, both to e. ledrew. m. drinkwater provided invaluable assist ance in the implcmentation of the microwave scattering models used hcre. we thank him for his guidance and encouragement throughout this project. references assur. a. 1960: composition of sea ice and its tensile strcngth, sipre research report 44. 86 pp. barber, d . g., johnson, d. & ledrew, e. f. 1991: measuring climatic statc variables from sar images of sea ice: the simms sar validation site in lancaster sound. arctic. 4 4 , 101-121. barber, d. g . , flett, d. g . , de abreu, r. a. & ledrcw, e. f. 1992a: spatial and temporal variations in sea ice geophysical properties and microwave remote sensing observations: the simms'90 experiment. arcric. 45131, 233-251. barber, d. g . . le drew, e. f.. shokr, m. & falkingham, j . 1992b: seasonal and diurnal variations in sar signaturcs of sea icc. ieee trans. geosci. remote sew. 30(3), 638-642. colbeck, s. c. 1981: the geometry and permittivity of snow at high frequencies. 1. appl. phys. 53(6), 4495-4500 crocker. g. b. 1984: the physical propertics of snowcover on sea ice in the central high arctic. department of geography, megill university, m.s. thesis. 180 pp. drinkwater, m. r. 1989: limex/87 ice surface charac teristin: implications for c-band s a r backscatter signatures. ieee trans. geosci. remote sens. 2 7 ( 5 ) , 501-513 drinkwater, m. r. & crocker, g . b. 1988: modeling changes in the dielectric and scattering properties of young snow covered sea ice at ghz frequencies. j . glaciol. 34(118), 274 282. frankenstein, g . &garner, r. 1967: equations for determining the brine volume of sea ice from -0.5 to -22.9 degrees c. j . glaciol. 6(48), 943-944. johansson, r. & askne, j . 1987: modeling of radar back scattering from low-salinity ice with ice ridges. internal. j . remote sens. 8(11), 1667-1677. hoekstra, p. & cappillino, p. 1971: dielectric properties of sea and sodium chloride ice at u h f and microwave frequencies. j . geophys. res. 7 6 , 4922-4931. kim. y. s. 1984: theoretical and experimental study of radar backscatter from sea ice. ph.d. dissertation, university of kansas. 168 pp. kim, y. s . . onstott, r . g. & moore, r. k. 1984: the effect of a snow cover on microwave backscatter from sea ice. ieee 1. oceanic engin. oe-915). 383-388. kim, y. s., moore, r . k.. onstott, r. g . & gogennini. s . 1985: towards identification of optimum radar parameters for sea ice monitoring. j . glaciol. 31(109), 214-219. livingstone, c. e., onstott, r. g., arsenault, l. d . , gray, l. & singh, k. p. 1987: microwdvc sea-ice signatures near the onset of melt. ieee trans. geosci. remote sens. g e 2 5 ( 2 ) , 174-187. livingstone. c . e . 1989: combined active/passive microwave classification of sea ice. e a r s 89. july 10-14, vancouuer canada i , 376380. livingstone, c . e. & drinkwater, m. r. 1991: springtime c-band sar backscatter signatures of labrador sea marginal ice: measurements versus modeling predictions. l e e e trans. geosci remote sens. 29(1), 2%41. matzler, c. 1987: applications of the interaction of microwaves with the natural snow cover. remore s e w . reo. 2 , 259-387. nakawo, m. & sinha, n. k. 1981: growth rate and salinity profile of first-year sea ice in the high arctic. 1. glaciol. 27(%), 315-330. tiuri. m. e., sihvola, a . h . , nyfors, e. g. & hallikainen, m. t. 1984: the complex dielectric constant of snow at micro wave frequencies. ieee j . oceanic engin. o e 9 ( 5 ) . 377 382 ulaby, f. t.. moore, r . k. & fung, a . k. 1086: microwaue remote sensing: acriue and passive. vol. 111. addison-wcsley publishing company, massachusetts. vant, m. r . , ramscicr, r. 0. & makios, v. 1978: the complex dielectric constant of sea ice at frequencies in the range 0.1 to 40 ghz. 1. appl. phys. 49(3), 12641280. winebrenner, d. p., tsang, l., wen, b. & west, r. 1989: sea iec characterizations measurements nccded for testing of microwave remote sensing models. ieee j . oceanic eng. 1412). 14s158. the immune response and diving: conservation considerations for belugas (delphinapterus leucas) in a changing arctic environment review article the immune response and diving: conservation considerations for belugas (delphinapterus leucas) in a changing arctic environment laura a. thompson & tracy a. romano research department, mystic aquarium, mystic, ct, usa abstract diving is a critical behaviour of marine mammals, including belugas, which dive to forage and travel under arctic sea ice. while the limitations of dive behaviour and physiological dive adaptations have been the focus of several studies, cellular adaptations, particularly those of the immune system, have been little considered. however, diving itself presents several challenges that can impact immune responses, leading to disease or injury. as beluga dive their behaviour changes in response to human activity or environmental shifts. it is necessary to better understand how the beluga’s immune system functions during diving. this review provides a brief overview of what is known about beluga’s diving behaviour and physiology and discusses the first efforts to understand the link between diving and health via immune function in belugas. this new area of research is an important consideration regarding potential sub-lethal impacts of a rapidly changing arctic environment on beluga’s diving behaviour, health and disease susceptibility. keywords dive physiology; decompression sickness; marine mammal; cetacean; immunity; health this article is part of the special cluster beluga whales (delphinapterus leucas): knowledge from the wild, human care and tek, which has been funded by mystic aquarium, caff and the norwegian ministry of climate and environment. abbreviations atm: atmospheres cd11b/18: cluster of differentiation 11b/18 dcs: decompression sickness hb: haemoglobin il2r: interleukin 2 receptor m/s: metres per second n2: nitrogen o2: oxygen owe: out of water examination sd: standard deviation se: standard error citation: polar research 2021, 40, 5499, http://dx.doi.org/10.33265/polar.v40.5499 copyright: polar research 2021. © 2021 l.a. thompson & t.a. romano. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 12 november 2021 competing interests and funding: the authors report no conflict of interest. portions of the reviewed research were funded by the office of naval research (award nos. n000141512203, n00014-11-1-0437 and n00014-13-1-0768); the national oceanic and atmospheric administrations oceans and human health initiative and interdisciplinary research and training initiative on coastal ecosystems and human health programme and the sea research foundation, inc. (d/b/a mystic aquarium). correspondence to: laura a. thompson, research department, mystic aquarium, 55 coogan blvd., mystic, 06355 ct, usa. e-mail: lthompson@searesearch.org introduction with the arctic region demonstrating greater sensitivity and faster warming compared to other global regions (post et al. 2019), arctic species are increasingly exposed to the impacts of anthropogenic activities, whether directly through increased shipping, noise and pollution and oil and gas exploration and mining, or indirectly through the effects of environmental/ecosystem shifts (huntington 2009; kovacs et al. 2011; hauser et al. 2018). such potential stressors can alter dive behaviour and, ultimately, health. diving is essential in marine mammals, enabling foraging and travel (martin et al. 1998), as well as helping in avoidance of potential threats such as boats (constantine et al. 2004; williams et al. 2017) and predators such as killer whales (jefferson et al. 1991). while the importance of diving for foraging may be apparent, the relationship between diving and health via disease or injury in marine mammals is less clear. this paper is not intended to be an exhaustive review of dive behaviour and physiology; rather, it provides an overview and discussion of the first research to consider adaptation of the immune system for diving and the implications of a changing arctic environment on health in the beluga (delphinapterus leucas). interest in marine mammal dive physiology appears to have had several boosts since the early observations of whalers. the latest resurgence in interest of dive physiology could perhaps be traced to reports of gas-bubble injury and dsc-like injury in several species of cetaceans in the early 2000s (jepson et al. 2003; fernandez et al. 2005; jepson et al. 2005) and has been aided by the development and improvement of tagging technologies that improved our understanding of dive behaviour and physiological responses (e.g., johnson & tyack 2003; cooke et al. 2004; evans et al. 2013; mcintyre 2014; williams et al. 2015). amongst the challenges associated with diving, issues of aerobic capacity and gas management have been the focus of a great deal of research that aims at helping us understand how marine mammals are able to make prolonged deep and repetitive dives without a direct source of o2 (e.g., scholander 1940; kooyman 1973; kooyman et al. 1981; kooyman & ponganis 1998; noren & williams 2000; kanatous et al. 2002; bostrom et al. 2008; macdonald & ponganis 2013). such studies also seek to elucidate the circumstances under which dcs-like injury is possible by investigating gas dynamics and cardiovascular and pulmonary function to determine the potential for gas-bubble formation (ridgway & howard 1979; hooker et al. 2012; fahlman et al. 2014; hodanbosi et al. 2016; garcia parraga et al. 2018). other health challenges that may be associated with diving include the effects of pressure changes, temperature changes and hypoxia/re-oxygenation on cellular processes and immune responses. for human divers, dive-related changes in immune function include cell aggregation and activation (nyquist et al. 2004), increased occurrence of certain infections (brenner et al. 1999) and inflammation, which also plays an important role in the development of injury from dcs (ward et al. 1987; nyquist et al. 2004; barack & katz 2005; montcalm-smith et al. 2007). beluga dive behaviour the beluga is a mid-sized odontocete demonstrating variable dive behaviour both between and within individual populations. belugas in the beaufort and chukchi seas dive several 100 m to over 900 m in off-shelf regions (citta et al. 2013; hauser et al. 2015); an adult male made the deepest recorded dive: 1160 m (citta et al. 2013). the majority of dives are often much shallower, and near-shore and coastal populations may be limited in terms of dive depth by constraints of local bathymetry. for example, hauser et al. (2015) reported that belugas on the shelf of the beaufort sea often dove to the bottom, which was not greater than 100 m depth, and dives of less than 10 m are common among belugas in the shallow bristol bay and cook inlet, alaska (goetz et al. 2012; laidre et al. 2017). male belugas off svalbard dive to less than 5 m approximately 60% of the time, even in deep water (vacquie-garcia et al. 2019). however, six belugas tagged near devon island, canada, spent only 20–39% of their time at a depth less than 5 m and had a maximum dive depth of 872 m (heide-jørgensen et al. 1998). the longest reported dive duration for a beluga is 31.4 min (vacquie-garcia et al. 2019); average dive durations range from 1.1 to 18 min (ridgway et al. 1984; martin et al. 1998; martin & smith 1999; kingsle et al. 2001; martin et al. 2001; goetz et al. 2012; citta et al. 2013; vacquie-garcia et al. 2019). deeper dives are usually longer in duration (martin & smith 1999; citta et al. 2013) but may have shorter bottom times or time spent foraging (martin & smith 1999). increased bottom time and, thus, maximal foraging opportunity may be achieved through ‘square’ dives, which have been reported to be the most common dive type (martin et al. 1998). other dive shapes may be indicative of the function of each dive, such as drifting, travelling or exploring (lefebvre et al. 2018). the occurrence of what is described as ‘interrupted square dives’ supports the idea that planned dives can be altered and highlights the need to understand the resilience of physiological and immune responses to such events. overall, the speed of descent and ascent appears to average around 2 m/s or less (table 1), with variability based on dive type (lefebvre et al. 2018). deeper, longer-lasting dives require a greater vertical distance travelled and result in increased swim speed during descent/ascent (martin & smith 1999). a progressive slowing was reported on decompression following long dives, as animals approached the surface (martin & smith 1992), and a series of shallow ‘recovery’ dives have also been reported following prolonged deep dives (richard et al. 1997). these behaviours may help recovery from dives that reach or exceed the adl or help regulate muscle washout of n2, though there is little evidence to support this (tyack et al. 2006). where deep dives do occur, they have been linked to foraging (martin & smith 1992; citta et al. 2013; hauser 2016; stafford et al. 2016) and movement under ice cover (e.g., suydam et al. 2005), so they vary by season and in connection with shifting distribution of prey species (watt et al. 2016), with more deep and prolonged dives occurring in the winter (heide-jørgensen et al. 1998; watt et al. 2016). table 1 summary of reported vertical swim speeds during diving in belugas. reference descent rate (m/s) ascent rate (m/s) ridgway et al. 1984a 2.27 ± 0.19 (m) 1.99 ±1 .47 (f) 2.25 ± 0.21 (m) 2.29 ± 0.26 (f) martin & smith 1992b 1.43 to 2.2 1.23 to 1.84 shaffer et al. 1997b <2 2.2 to 3 martin et al. 1998c 0.5 ± 0.24 to 1.7 ± 0.02 0.45 ± 0.12 to 1.76 ± 0.06 martin & smith 1999b 1.5 to1.85 1.37 to 1.97 martin et al. 2001d 1.42 (1.1 to 1.7) 1.73 (1.7 to 1.8) lefebvre et al. 2018 b 0.15 to 0.87 0.22 to 0.63 vertical speed (m/s) heide jørgensen et al. 1998b 0.5 to >2 hauser et al. 2015b <2 kingsle et al. 2001e 1.99 (se 0.025) –2.19 (se 0.028) areported as mean ± sd. breported as range. creported as mean ± 2 sd. dmean (range). emeans and se. recent studies suggest that deep dives occur more often in some populations in response to shifts in the vertical distribution of prey, driven by ocean warming and shifting currents (stafford et al. 2016; watt et al. 2016; hauser et al. 2018); there is also a suggestion that dives exceeding 20 min in duration are becoming more frequent (hauser 2016). surface behaviour of belugas can be interrupted by human presence, as illustrated by animals in bristol bay observed to end milling or feeding behaviours at the water surface and submerge for longer periods of time in response to approaching boats and in some cases swimming at increased speeds as a potential avoidance behaviour (l. thompson, pers. obs. 2014, 2016). belugas may also show extreme avoidance of large ships, such as ice breakers, though a lot of variability is noted in the response of these animals to human activities (richardson & wursig 1997). while belugas have been shown to vary their dive behaviour, these forced changes in dive activity in response to anthropogenic stressors or environmental changes may have unforeseen health implications. it is possible that occasional dives to 1000 m are not a problem for belugas but increasing the necessity for such deep dives may push an animal past its physiological limits. ridgway et al. (1984) noted that the deepest dives of 600 m appeared challenging for the adult female in their study. this was a captive managed individual maintained in sea-pens in san diego bay. san diego bay is significantly shallower than 600 m, with a maximum depth of about 18–20 m, which may have limited this individual’s previous experience with deep dives. physiological responses may then be related to the dive history or experience of an individual animal and will therefore vary in wild populations: if generally shallow-diving populations need to make increasingly deeper foraging dives, they may struggle more than those with a history of diving deeper. however, before we can evaluate the impact of altered dive responses, it is first necessary to determine how the immune system functions during normal dive behaviours. general dive adaptation of marine mammals to dive, belugas and other marine mammals have developed physiological, anatomical and behavioural adaptations to combat the issues of o2 availability and pressure, as has been reviewed elsewhere (e.g., kooyman et al. 1981; kooyman & ponganis 1998; ponganis 2015). a markedly pronounced dive response, including vagally mediated bradycardia and sympathetically controlled peripheral vasoconstriction, reduces cardiac output and blood flow to peripheral tissues, conserving blood o2 for critical tissues (kooyman et al. 1981). initially termed the dive reflex, it is now known that this response can occur on a gradient, based on dive characteristics such as a forced submersion versus free diving (kooyman & campbell 1972), depth or duration (hindle et al. 2010; mcdonald et al. 2018) and activity levels (davis & williams 2012; noren et al. 2012; mcdonald et al. 2018), and can even be cognitively controlled (ridgway et al. 1975; elmegaard et al. 2016). increased o2 stores, including circulating red blood cells and haemoglobin per cell, and myoglobin in muscle (kooyman et al. 1981; ponganis &williams 2015), reduce metabolic activity, possibly indicated by decreased body temperature (e.g., weddell seals [kooyman et al. 1980]), and balancing stroke and gliding behaviours (williams et al. 2000) also aid in prolonging the duration of aerobic dives. increased capacity for anaerobic metabolism also has been reported for some species (elsner et al. 1998). marine mammals possess collapsible lungs, which, along with the dive response, also protect against dcs, due to reduction of gas exchange in the lungs as well as tissue perfusion (kooyman & ponganis 1998). recent studies suggest that n2 levels may reach supersaturation under certain conditions (houser et al. 2001; zimmer & tyack 2007) and more questions have arisen about how marine mammals balance the physiological adjustments of the dive response, exercise response and escape response. furthermore, species differences in dive behaviour and physiology have become a focus of discussion, as shallowand deep-diving species and even ecotypes may display variable responses (e.g., hindle et al. 2010; cantu-medellin et al. 2011). our understanding of dive responses, and how marine mammals avoid dive-related injury and disease, remains incomplete. beluga dive physiology studies specifically focused on beluga dive physiology are relatively few but make use of access to belugas both in professional human care or tissues collected post mortem from subsistence hunts through collaboration with indigenous communities. as early as 1974, greater blood o2 capacity was reported in belugas compared to other cetaceans, such as the killer whale (dhindsa et al. 1974). open-water studies conducted by the us navy marine mammal program appear to confirm high haemoglobin concentration and haematocrit, which would increase o2 storage capacity, allowing longer aerobic dives (ridgway et al. 1984). table 2 summarizes several haematological parameters that aid in o2 storage and therefore in aerobic dive ability in belugas as compared with humans and the bottlenose dolphin (tursiops truncatus), generally considered a shallow-diving species; the table also shows the similarity between values in belugas and the deep-diving northern elephant seal (mirounga angustriostris). however, despite belugas’ increased blood o2 stores, hedrick & duffield (1991) report limited o2 transport and conclude that belugas may be limited in their activity level (speed) during a dive. belugas also possess increased capacity for muscle o2 storage (myoglobin), muscle buffering capacity, red blood cell counts, haemoglobin and haematocrit, which have been reported to reach mature levels prior to weaning in belugas, which is faster than observed in other marine mammals (noren & suydam 2016; noren et al. 2018; choy et al. 2019). table 2 reported haematology values for increased blood o2 storage in belugas as compared with elephant seals, bottlenose dolphins and humans. reference species hb g/dl mb mg/g hcta% mcvb mchc mchcd total o2 stores ml/kg dhindsa et al. 1974 belugae 19.3 46 134.13 57.36 42.77 hedrick & duffield 1991 belugae 21.6 59 177 64.07 36 ridgway et al. 1984 belugaf 20.9 ± 0.9 (m) 20.3 ± 0.2 (f) 52.6 ± 4.3 (m) 52.2 ± 2.6 (f) st. aubin et al. 2001 belugag 21.3–22 58–60 159–164 58–61 36–37 choy et al. 2019 belugah 21.2±1 (m) 23.4 ± 0.4 (f) 83.2 ± 2.1 (m) 84.1 ± 0.9 (f) 55 ± 2.1 (m) 59.6 ± 1.3 (f) 58.7 noren & williams 2000 belugah 34.4 ±3.9 51.9 hedrick & duffield 1991 n. elephant seale 25.3 64 182.5 69.75 38.2 hassrick et al. 2010 n. elephant seal 78 ± 13 (f) 57 ± 4 (f) 92.8 (f) goldstein et al. 2006 bottlenose dolphinf 11.3–18.2 37.13–47.27 107–129 37–44 32–36 ponganis & williams 2015 bottlenose dolphin 34 human 24 wakeman et al. 2007 humang 12–17.2 37–50 83–98 28–33 32–36 ahaematocrit. bmean corpuscular value. cmean corpuscular haemoglobin. dmean corpuscular haemoglobin concentration. ereported as mean. freported as mean ± sd. grange. hmean + se. the aerobic dive limit for belugas was estimated to be 9–10 min based on post-dive lactate measurements during an open-water study and estimates of body o2 stores and metabolic rate (shaffer et al. 1997). however, martin & smith (1999) purport that this is an underestimation based on study design and individual animal behaviour. they suggest the adl is at least twice that estimated, which matches with the range of average reported dive durations (1–18 min; see above) and would agree with most dives remaining aerobic (martin & smith 1998). if belugas do dive anaerobically, adaptation in nitric oxide metabolism may aid in protection during such dives (fago et al. 2017). as with other species, body size appears to influence dive ability based on o2 stores, as smaller animals have been reported to perform fewer deep dives, spend less time at depth and require longer surface intervals (heide-jørgensen et al. 1998; martin & smith 1999). further adaptations to diving include the anatomy of the beluga heart (bisaillon et al. 1988) and aspects of cardiac and pulmonary function (fahlman et al. 2019; fahlman et al. 2020). to the best of our knowledge, however, cellular adaptations to diving have not previously been of focus in beluga studies, and, with the exception of the connection to foraging, the direct relationship between diving and health has been little considered. beluga immune function during diving multiple aspects of dive behaviour and physiology have the potential to impact or alter immune activity during, or following, a dive including: pressure; changes in o2 availability; metabolic rate and activity level and bi-products in muscle; presence of a stressor; circulating hormone levels (such as catecholamines, which help regulate vasoconstriction) and potential formation of gas bubbles upon decompression. there is a complicated relationship between each of these factors (e.g., stressors may directly impact the dive response or may alter activity which then alters the dive response (fig. 1). during a dive, effects may occur on cells found in tissue (e.g., macrophages) or in circulation. even though drastic reductions in peripheral perfusion occur during the dive response, the variability in this response (as described above) suggests that some circulation and perfusion may persist during natural dives. while the direct effect of pressure on cells may be restricted to deeper depths (>500 m), belugas have been shown to reach such depths within their natural repertoires (citta et al. 2013; hauser et al. 2015). the challenges related to o2 availability, activity level, metabolic rate and hormones may be of consideration for comparatively shallower dives. work conducted in our laboratory has been the first to consider beluga immune function in the context of diving, aimed at a better understanding of the adaptation of the immune system to the aquatic environment, and to evaluate the potential for stressors to impact marine mammal health. to date, there have been only four studies directly evaluating immune function in response to the challenges associated with diving in belugas, and these have only begun to consider the effects of pressure, gas bubbles, apnea and activity level. fig. 1 a simplified diagram illustrating the relationship between physiological challenges associated with diving that may alter immune function. environmental and anthropogenic stressors may also have indirect impacts (e.g., stressors alter activity that may modulate the dive response in such a way as to allow the development of n2 bubbles, which then trigger immune responses). effects of pressure on immune function over the course of a dive, pressure increases by 1 atm for every 10 m of depth. a main consideration of pressure is the effects on air-filled spaces; pressure can also alter cell function by reducing process volumes (bartlett 2002), ordering of membrane structures and reducing membrane fluidity, which in turn alters ion channel function, permeability, receptor binding and therefore the transmission of external to internal signalling (reviewed in macdonald 1982; heinemann et al. 1987; somero 1992; haskin & cameron 1993; kato & hayashi 1999; daniels & grossman 2003; pradillon & gaill 2007). in addition, gene expression and protein synthesis may be altered (bartlett et al. 1995; pradillon & gaill 2007) and the progression of the cell cycle and cell division may be slowed (macdonald 1982). innate immunity present from birth, innate immunity includes non-specific defense mechanisms that recognize general signals of ‘non-self’ and include inflammatory processes, as well as certain cell functions. phagocytosis is a process by which immune cells engulf infectious agents, foreign particles and cell debris, after which such particles can be destroyed intracellularly. phagocytosis involves membrane receptor binding and membrane fluidity, which allows for membrane extension to surround and engulf the foreign particle (murphy et al. 2008). the phagocytic response can be ‘primed’ or ‘activated’ as compared with a resting state, resulting in increased expression of cell surface proteins that facilitate binding, leading to stronger responses when an actual challenge is present (downey et al. 1995). one such protein is the adhesion complex macrophage 1 antigen, which is composed of two heterodimers; cd11b and cd18. this protein enables phagocytosis (graham et al. 1989) and has also been implicated in tissue damage (orr et al. 2007). the effects of pressure on phagocytic activity in belugas were investigated by exposing fresh blood samples to simulated dives utilizing a steel benchtop pressure chamber and hydraulic pump (thompson & romano 2015). two target pressures (depths) were used to represent an extreme dive to 1360 m (2000 psi) and a deep dive to 640 m (1000 psi), which may be more common for wild belugas. in addition, the speed of compression and decompression (descent/ascent) and the duration spent at each target pressure (30 min, 5 min or two repeated 5 min) were controlled and varied. results varied with the characteristics of each simulated dive (depth, duration, rate of compression and decompression); in general, larger changes were observed for exposures to greater pressure (deeper) and with faster rates of compression/decompression (fig. 2). an overall decrease in phagocytic activity was observed in these baseline samples, suggesting a pressure-induced down-regulation of function, possibly mediated by the direct effect of pressure on membrane characteristics. increased pressure can decrease membrane fluidity and reduce the fusion of membranes, limiting both cellular ingestion and degranulation (heinemann et al. 1987). this is further supported as expression of cd11b displayed minimal changes, suggesting that the overall activation state was not influenced. while a dive to 1360 m (2000 psi) would represent an extreme dive for belugas, the decreased innate function seen in this study immediately following pressure exposures either returned to normal or increased following a 20-min post-exposure recovery period (at ambient pressure), suggesting that the effect of pressure on the cells is reversible and may therefore not result in serious health implications. however, this was a single exposure, and the cumulative effects of repeated deep and prolonged dives were not explored. fig. 2 changes in (a) granulocyte and (b) monocyte phagocytosis measured in beluga blood samples (n = 4) following simulated dive exposures (i.e., pressure). samples were exposed to either 2000 psi (1360 m) or 1000 psi (640 m), with compression and decompression occurring either gradually over two min (g) or rapidly in 15 s (r). data have been normalized to controls (represented by the solid line at 1) and presented as the mean change in function ± se. values greater than 1 indicate increased function, and values less than 1 indicate decreased function following pressure exposure. significant differences between exposures (p < 0.05) are indicated by letters (a, b, c). (reprinted from thompson & romano 2015; figures 1a, 2a.) adaptive immunity adaptive, or acquired, immunity develops through exposure to potential health threats and is responsible for immunological memory leading to more efficient responses with repeated exposure. recognition of nearly any possible pathogen is accomplished through high diversity of receptors on t lymphocytes, yet few cells express any given combination of receptors (murphy et al. 2008). in order to mount an effective response, cells that recognize a pathogen must then be able to rapidly produce clones with the same recognition capability, a process called lymphocyte proliferation (king & stott 2002; murphy et al. 2008). similar to phagocytes, lymphocytes can be activated through binding of cell membrane receptors, and the clustering of cell membrane components. such activation results in production of the cell signalling molecule interleukin 2 (il2), which acts as both an autocrine and paracrine signal, as well as an up-regulator of the il2 receptor in the cell membrane (tizard 2000). thompson & romano (2016) used the same in vitro approach as described for the innate immune function study to evaluate the effect of simulated dives on lymphocyte proliferation and activation. similar to the phagocytosis results, a general decrease in function was detected following pressure exposure in baseline beluga samples (fig. 3). however, in contrast to phagocytes, which did not display pressure-induced activation (increased cd11b), expression of il2r increased in response to pressure exposures. this presents an interesting disconnect between activation state and cell activity, suggesting that even though cells are activated, they may be unable to proliferate because of the mechanical effects of pressure on membrane function or intracellular processes. fig. 3 lymphocyte proliferation in aquarium belugas during baseline (n = 4) and owe conditions (n = 3) in belugas from bristol bay (n = 9) and humans (n = 4) following exposures to 2000 psi (1360 m) with two min of compression and decompression. data are normalized to controls (represented by the solid line at 1 and are presented as the mean ± se). values greater than 1 indicate increased function, and values less than 1 indicate decreased function following pressure exposures. within each duration, significant differences between conditions in belugas or between belugas and humans are indicated with letters (a, b) (p < 0.05). significant differences from controls are indicated with an asterisk (p < 0.05). (reprinted from thompson & romano 2016; figure 1d.) combined effect of pressure and additional stressors diving itself is a challenging behaviour that requires several physiological adjustments. increased hormone expression, for example, serves to regulate certain aspects of the dive response, such as vasoconstriction (hance et al. 1982; hochachka et al. 1995; butler & jones 1997). catecholamines, such as epinephrine and norepinephrine, as well as neuroendocrine activation are also important regulators of the mammalian stress response and can directly and indirectly modulate immune responses (romano et al. 2002; padgett & glaser 2003). there is interest in the interplay of these two responses, and concern that a sudden stress response during a dive could result in abnormal or extreme physiological responses (talpalar & grossman 2005). in studies on pressure effects on immune function, several paradigms were used to sample belugas under opportunistic ‘stressor’ conditions. for aquarium belugas, an owe, where animals were stretchered and removed from the water for a full 30-min veterinary examination, resulted in increased measures of catecholamines and significantly higher serum cortisol (thompson & romano 2015) and had previously been reported to increase adrenocorticotropic hormone and cortisol (schmitt et al. 2010). samples collected following this 30-min owe resulted in greater changes in granulocyte phagocytosis following in vitro pressure exposures, including significant increases in function during the recovery periods (fig. 4). lymphocytes also displayed larger pressure-induced changes in function following the owe (thompson & romano 2016). fig. 4 changes in granulocyte phagocytosis following exposures to 2000 psi (1360 m) with two min of compression and decompression, measured in belugas baseline (n = 4), owe (n = 3) and inflammation (n = 2) conditions, and humans (n = 4). data have been normalized to controls (represented by the solid line at 1) and presented as the mean change in function ± se. values greater than 1 indicate increased function, and values less than 1 indicate decreased function following pressure exposures. significant differences between belugas and humans or between conditions in belugas are indicated with letters (a, b) (p < 0.05). (reprinted from thompson & romano 2015; figure 4a.) wild belugas in bristol bay sampled under restraint in shallow water during live-capture/release health assessment efforts, provided an additional stressor paradigm for testing lymphocyte function (thompson & romano 2016). these samples displayed higher proliferative responses as compared to both aquarium baseline and owe samples, which resembled those measured in human samples more closely (see fig. 3). under such a situation, this similarity may indicate greater risk of dive-related disease in belugas that dive while facing additional significant stressors, such as shipping, pollution, increased sound levels, oil spills and other effects of human activities. response to n2 bubbles thompson & romano (2015, 2016) present the first data supporting the hypothesis that marine mammals, such as the beluga, may display a down-regulation of certain immune functions (e.g., phagocytosis and proliferation) during diving and that this may protect against unwanted immune activity, such as inflammation leading to tissue damage. because the development of dcs injury has been linked to changes in immune activity, this down-regulation may be one mechanism through which marine mammals avoid dcs-like injury during diving. increased cellular function measured in opportunistic stressor samples, particularly during recovery periods (i.e., after decompression) and responses that resemble those observed in human samples may indicate conditions during which belugas are more susceptible to dive-related injury. while the possibility of gas-bubble formation during decompression in diving cetaceans is still under question, dcs is not limited only to scuba or saturation dives and can occur during breath-hold diving (wong 2006; schipke et al. 2006) and there is some evidence that n2 supersaturation could occur under certain circumstances (houser et al. 2001; jepson et al. 2003). yet for human divers, the occurrence of gas bubbles alone does not equal dcs and so-called ‘silent bubbles’ can occur without the development of symptoms (barack & katz 2005), possibly due to reduction in immune responsiveness (e.g., kayar et al. 1996). with the aim of directly testing the potential response of beluga inflammation to potential n2 gas bubbles, thompson et al. (2020) exposed serum to various flows of n2 gas in vitro. while human samples were not included in this study, a significant activation of the complement response was reported, measured as a significant increase in the protein c5a, in human and rabbit sera exposed to air flow at a rate of 0.5 ml/min for 30 min (bergh et al. 1993). this flow rate failed to trigger a similar significant increase in c5a (inflammatory activation) in either aquarium beluga baseline samples or wild live-capture/release belugas (stressor) samples (fig. 5). however, a higher flow rate of 1 ml/min did result in a significant increase in c5a in wild beluga samples, suggesting that the additional stressor of chase and restraint may alter the sensitivity of the complement system. this work also suggests that there may be a threshold of bubble load before belugas (or other marine mammals) are at risk, and this may be greater than that of humans and other terrestrial animals. fig. 5 change in serum c5a with n2 bubble exposures compared to controls in narwhal (n = 5) and beluga (aquarium n = 7, bristol bay n = 9). bubble exposures were of 30 min at either 0.5 or 1 ml/min n2. data were normalized to control values for each sample and are represented as the mean δc5a ± se. box and whisker plots indicate the median and quartile ranges for each sample group. means are indicated by an “x”. the significant exposure-induced increase in mean c5a for bristol bay belugas is denoted with an asterisk. significant differences in the response of c5a between species are indicated with letters (a, b). (reprinted from thompson et al. [2020] with permission from springer nature customer service centre gmbh: springer nature [journal of comparative physiology b. variation in hemostatic complement (c5a) responses to in vitro nitrogen bubbles in monodontids and phocids].) interestingly, in this study, serum from the closely related narwhal (monodon monoceros) also sampled under restraint conditions, were subject to the same in vitro n2 exposures but did not display any significant activation of complement, even at the highest flow rate, which significantly affected wild belugas (fig. 5). narwhals are comparatively deeper divers than belugas, reaching maximum depths of over 1500 m (heide-jørgensen et al. 2015) and these results suggest species-specific responses to stress (coping styles), varying susceptibility to dive-related injuries and sensitivity to forced changes in dive behaviour. the need for in vivo studies these early studies were carried out in vitro, utilizing both fresh and frozen archived samples. in vivo investigations are a critical next step to place results within the context of various physiological adjustments that occur during diving. preliminary in vivo studies utilizing a single beluga (thompson & romano 2019) collected blood samples following two different trained dive behaviours: (1) stationary dive in which the whale remains submerged under water and stations on a target, and (2) active dive in which the whale swims between targets while submerged. only one dive behaviour occurred in a single day. each dive behaviour lasted for a duration of three min and each behaviour was sampled three times. blood samples were collected by veterinary staff from the ventral aspect of the fluke under behavioural participation by the individual whale. plasma catecholamines were measured using high-performance liquid chromatography and c5a was measured with and without in vitro exposure to n2 bubbles. while no statistical analysis can yet be run on this data, thompson & romano (2019) showed an observed increase in norepinephrine during each dive behaviour, suggesting that 3 min was sufficient to initiate a mammalian dive response (fig. 6). additionally, there appeared to be an increase in circulating c5a following both dive types, which was greater and less variable following the stationary dives as compared with the active dives (fig. 7). furthermore, exposure to in vitro n2 bubbles following these dive behaviours resulted in huge increases in c5a as compared with the individuals’ baseline samples and the beluga baseline data reported by thompson et al. (2020; fig. 8). such results indicate that there may be other physiological factors that influence inflammatory activation during diving, including apnea and activity level. as o2 plays a key role in cell metabolism, certain immune responses (e.g., oxidative burst) and re-oxygenation can induce inflammation; further studies investigating the effects of hypoxia are warranted. fig. 6 plasma norepinephrine measured in a single beluga during monthly blood draws (n = 7; baseline) and following specific active and stationary dive behaviours. each dive behaviour was replicated three times. fig. 7 serum concentration of c5a measured in a single beluga during monthly blood draws (baseline) and following specific active and stationary dive behaviours. each category includes three replicates. fig. 8 calculated changes in c5a following 30 min in vitro exposures to n2 gas bubbles at flow rates of either 0.5 or 1 ml/min. aquarium beluga baseline (n = 7) are re-reported from thompson et al. (2020). the individual baseline presents a single measure, while three replicates were completed for each dive type. while in vitro approaches allow for the effects of individual parameters (pressure, bubble presence) to be isolated and examined, in vivo studies are needed to understand immune function in the whole animal. further studies utilizing trained belugas are being developed in order to increase the sample size for this research as well as to target longer duration behaviours. shaffer et al. (1997) reported behavioural dives of 13 min, with stationary breath-holds of 17 min. these durations would be of particular value as they may begin to reach adl and would thereby provide information relevant to animals performing at or near their physiological limits. summary and conclusion diving is a critical behaviour for cetaceans. for belugas, the ability to dive to depths is necessary for foraging as well as prolonged periods when navigating under the arctic ice and they are well-adapted to diving at various depths and durations. there have been relatively few direct studies of beluga dive physiology, especially at the cellular level. more research is needed to better understand the impacts of changing dive behaviour on beluga health. as with other physiological processes, it is possible that the marine mammal immune system has some dive adaptation as immune activity is not only necessary for maintaining health and homeostasis but also plays an important role in dive-related injury and disease, including dcs. here we have recounted the first studies to consider immune function in belugas in the context of diving. results of this effort suggest that beluga immune responses are less sensitive to the challenges associated with diving, as compared with humans, but that these responses can be altered by stressors, including anthropogenic activities. both in vivo and in vitro aspects of this work measured end-dive changes, and new approaches and technology are needed to investigate mid-dive function. it is clear that more work is needed to better understand the complicated relationship between immune function, diving and health in belugas. rapid changes occurring in the arctic and subarctic regions may force changes in beluga dive behaviour. belugas are diving deeper and longer during foraging (hauser 2016; stafford et al. 2016) and it is unknown if this will push animals—such as smaller belugas, which make shallower, shorter dives, with longer inter-dive intervals at the surface (heide-jørgensen et al. 1998)—past their physiological limits. reduced dive ability has also been linked to reduced o2 stores in animals with poor body condition (choy et al. 2019). poor nutrition affects both dive ability and immune function (e.g., chandra 1999). as the ice cover declines, increased human presence may directly alter beluga dive behaviour, resulting in decreased surface time. if this should interrupt inter-dive or post-dive recovery, lactate levels could increase (shaffer et al. 1997) with as yet unknown implications for immune responses as lactate has been linked to both perpetuating inflammation (haas et al. 2015) and regulating inflammation during hypoxia (ivashkiv 2020). if interruption of natural dive behaviours increases the potential for n2 bubble formation, this, in combination with the physiological response to environmental stressors or boat noise, may leave belugas more susceptible to dive-related injury. the consequences of human activity and shifting arctic environment on beluga health may not be as apparent as mass strandings or physical injury. there is likely a complicated balance between immune activity and diving physiology, behavioural responses and health that can be impacted by abnormalities in any one system. research investigating the immune system’s role in diving is critical in understanding potential sub-lethal impacts of a rapidly changing arctic on beluga diving behaviour and physiology, health and disease susceptibility. acknowledgements this constitutes scientific contribution no. 345 from the sea research foundation, inc. a version of this paper was presented at the second international workshop on beluga whale research and conservation, 12–14 march 2019, held at mystic aquarium. references barack m. & katz y. 2005. microbubbles: pathophysiology and clinical implications. chest 128, 2918–2932, doi: 10.1378/chest.128.4.2918. bartlett d.h. 2002. pressure effects on in vivo microbial processes. biochimica et biophysica acta 1595, 367–381, doi: 10.1016/s0167-4838(01)00357-0. bartlett d.h., kato c. & horikoshi k. 1995. high-pressure influences on gene and protein expression. research in microbiology 146, 697–706, doi: 10.1016/0923-2508(96)81066-7. bergh k., hjelde a., iversen o.-j. & brubakk a.o. 1993. variability over time of complement activation induced by air bubbles in human and rabbit sera. journal of applied physiology 74, 1811–1815. bisaillon a., martineau d., st-pierre m.a. & beland p. 1988. arterial and venous vasculature of the heart of the beluga whale (delphinapterus leucas). journal of morphology 195, 305–312, doi: 10.1002/jmor.1051950305. bostrom b.l., fahlman a. & jones d.r. 2008. tracheal compression delays alveolar collapse during deep diving in marine mammals. respiratory physiology & neurobiology 161, 298–305, doi: 10.1016/j.resp.2008.03.003. brenner i., shephard r.j. & shek p.n. 1999. immune function in hyperbaric environments, diving, and decompression. undersea and hyperbaric medicine 26, 27–39. butler p.j. & jones d.r. 1997. physiology of diving of birds and mammals. physiological reviews 77, 837–899. cantu-medellin n., byrd b., hohn a., vasquez-medina j.p. & zenteno-savin t. 2011. differential antioxidant protection in tissues from marine mammals with distinct diving capacities. shallow/short vs. deep/long divers. comparative biochemistry and physiology a 158, 438–443, doi: 10.1016/j.cbpa.2010.11.029. chandra r.k. 1999. nutrition and immunology: from the clinic to cellular biology and back again. proceedings of the nutritional society 58, 681–683, doi: 10.1017/s0029665199000890. choy e.s., campbell k.l., berenbrink m., roth j.d. & loseto l.l. 2019. body condition impacts blood and muscle oxygen storage capacity of free-living beluga whales (delphinapterus leucas). journal of experimental biology 222, article no. jeb191916, doi: 10.1242/jeb.191916. citta j.j., suydam r.s., quakenbush l.t. frost k.j. & o’corry-crowe g.m. 2013. dive behavior of eastern chukchi beluga whales (delphinapterus leucas), 1998–2008. arctic 66, 389–406, doi: 10.14430/arctic4326. constantine r., brunton d.h. & dennis t. 2004. dolphin-watching tour boats change bottlenose dolphin (tursiops truncates) behaviour. biological conservation 117, 299–307, doi: 10.1016/j.biocon.2003.12.009. cooke s.j., hinch s.g., wikelski m., andrews r.d., kuchel l.j., wolcott t.g. & butler p.j. 2004. biotelemetry: a mechanistic approach to ecology. trends in ecology & evolution 19, 334–343, doi: 10.1016/j.tree.2004.04.003. daniels s. & grossman y. 2003. biological effects of pressure. in a.o. brubakk & t.s. neuman (eds.): bennet and elliott’s physiology and medicine of diving. pp. 265–299. edinburgh: wb saunders. davis r.w. & williams t.m. 2012. the marine mammal dive response is exercise modulated to maximize aerobic dive duration. journal of comparative physiology part a 198, 583–591, doi: 10.1007/s00359-012-0731-4. dhindsa d.s., metcalfe j., hoversland a.s. & hartman r.a. 1974. comparative studies of the respiratory functions of mammalian blood. x. killer whale (orcinus orca linnaeus) and beluga whale (delphinapterus leucas). respiration physiology 20, 93–103. downey g.p., fukushima t., fialkow l. & waddell t.k. 1995. intracellular signaling in neutrophil priming and activation. seminars in cell biology 6, 345–356. elmegaard s.l., johnson m., madsen p.t. & mcdonald b.i. 2016. cognitive control of heart rate in diving harbor porpoises. current biology 26, r1175–r1176, doi: 10.1016/j.cub.2016.10.020. elsner r., oyasaeter s., almaas r. & didrik saugstas o. 1998. diving seals, ischemia-reperfusion and oxygen radicals. comparative biochemistry and physiology a 119, 975–980. evans k., lea m.a. & patterson t.a. 2013. recent advances in bio-logging science: technologies and methods for understanding animal behaviour and physiology and their environments. deep-sea research part ii special issue 88–89, 1–6, doi: 10.1016/j.dsr2.2012.10.005. fago a., parraga d.g., petersen e.e., kristensen n., giouri l. & jensen f.b. 2017. a comparison of blood nitric oxide metabolites and hemoglobin functional properties among diving mammals. comparative biochemistry and physiology a 205, 35–40, doi: 10.1016/j.cbpa.2016.12.013. fahlman a., epple a., garcia-parraga d., robeck t., haulena m., piscitelli-doshkov m. & brodsky m. 2019. characterizing respiratory capacity in belugas (delphinapterus leucas). respiratory physiology & neurobiology 260, 63–69, doi: 10.1016/j.resp.2018.10.009. fahlman a., miedler s., marti-bonmati l., ferrero fernandez d., munoz caballero p., arenarez j., rocho-levine j., robeck t. & blawas a. 2020. cardiorespiratory coupling in cetaceans; a physiological strategy to improve gas exchange? journal of experimental biology 223, article no. jeb.226365, doi: 10.1242/jeb.226365. fahlman a., tyack p.l., miller p.j.o. & kvadsheim p.h. 2014. how man-made interference might cause gas bubble emboli in deep diving whales. frontiers in physiology 5, article no. 13, doi: 10.3389/fphys.2014.00013. fernandez a., edwards j.f., rodriquez f., espinosa de los monteros a., harraeq p., castro p., jaber j.r., martin v. & arbelo m. 2005. “gas and fat embolic syndrome” involving a mass stranding of beaked whales (family ziphiidae) exposed to anthropogenic sonar signal. veterinary pathology 42, 446–457, doi: 10.1354/vp.42-4-446. garcia parraga d., moore m. & fahlman a. 2018. pulmonary ventilation–perfusion mismatch: a novel hypothesis for how diving vertebrates may avoid the bends. proceedings of the royal society b 285, article no. 20180482, doi: 10.1098/rspb.2018.0482. goetz k.t., robinson p.w., hobbs r.c., laidre k.l., huckstadt l.a. & shelden k.e.w. 2012. movement and dive behavior of beluga whales in cook inlet, alaska. afsc processed report 2012–03. seattle, wa: alaska fisheries science center, national marine fisheries service, us dept. of commerce. goldstein j.d., reese e., reif j.s., varela r.a., mcculloch s.d., defran r.h., fair p.a., bossart g.d. & hansen l. 2006. hematologic, biochemical and cytological findings from apparently healthy atlantic bottlenose dolphins (tursiops truncates) inhabiting the indian river lagoon, florida, usa. journal of wildlife diseases 42, 447–454, doi: 10.7589/0090-3558-42.2.447. graham i.l., gresham h.d. & brown e.j. 1989. an immobile subset of plasma membrane cd11b/cd18 (mac-1) is involved in phagocytosis of targets recognized by multiple receptors. journal of immunology 142, 2352–2358. haas r., smith j., rocher-ros v., nadkarni s., montero-melendez t., d’acquisto f., bland e.j., bombardieri m., pitzalis c., perretti m., marelli-berg f.m. & mauro c. 2015. lactate regulates metabolic and pro-inflammatory circuits in control of t cell migration and effector functions. plos biology 13, e1002202, doi: 10.1371/journal.pbio.1002202. hance a.j., robin e.d., halter j.b., lewiston n., robin d.a., cornell l.m. & theodore j. 1982. hormonal changes and enforced diving in the harbor seal phoca vitulina. ii. plasma catecholamines. the american journal of physiology 242, r528–r532, doi: 10.1152/ajpregu.1982.242.5.r528. haskin c. & cameron i. 1993. physiological levels of hydrostatic pressure alter morphology and organization of cytoskeletal and adhesion proteins in mg-63 osteosarcoma cells. biochemistry and cell biology 71, 27–35, doi: 10.1139/o93-005. hassrick j.l., crocker d.e., teutschel n.m., mcdonald b.i., robinson p.w., simmons s.e. & costa d.p. 2010. condition and mass impact oxygen stores and dive duration in adult female northern elephant seals. journal of experimental biology 213, 585–592, doi: 10.1242/jeb.037168. hauser d.d.w. 2016. beluga whale distribution, migration, and behavior in a changing pacific arctic. phd thesis, university of washington. hauser d.d.w., laidre k.l., parker-stetter s.l., horne j.k., suydam r.s. & richard p.r. 2015. regional diving behavior of pacific arctic beluga whales delphinapterus leucas and possible associations with prey. marine ecology progress series 541, 245–264, doi: 10.3354/meps11530. hauser d.d.w., laidre k.l., stern h.l., suydam r.s. & richard p.r. 2018. indirect effects of sea ice loss on summer–fall habitat and behaviour for sympatric populations of an arctic marine predator. biodiversity research 24, 791–799, doi: 10.1111/ddi.12722. hedrick m.s. & duffield d.a. 1991. haematological and rheological characteristics of blood in seven marine mammal species: physiological implications for diving behaviour. journal of zoology 225, 273–283, doi: 10.1111/j.1469-7998.1991.tb03816.x. heide-jørgensen m.p., nielsen n.h., hansen r.g., schmidt h.c., blackwell s.b. & jørgensen o.a. 2015. the predictable narwhal: satellite tracking shows behavioural similarities between isolated subpopulations. journal of zoology 297, 54–65, doi: 10.1111/jzo.12257. heide-jørgensen m.p., richard p.r. & rosing-asvid a. 1998. dive patterns of belugas (delphinapterus leucas) in waters near eastern devon island. arctic 51, 17–25, doi: 10.14430/arctic1041. heinemann s.h., conti f., stuhmer w. & nehe e. 1987. effects of hydrostatic pressure on membrane processes. sodium channels, calcium channels, and exocytosis. proceedings of the national academy of sciences 84, 3229–3233, doi: 10.1085/jgp.90.6.765. hindle a.g., young b.l, rosen d.a.s., haulena m. & trites a. 2010. dive response differs between shallowand deep-diving steller sea lions (eumetopias jubatus). journal of experimental marine biology and ecology 394, 141–148, doi: 10.1016/j.jembe.2010.08.006. hochachka p.w., liggins g.c., guyton g.p., schneider r.c., stanek k.s., hurford w.e., creasy r.k., zapol d.g. & zapol w.m. 1995. hormonal regulatory adjustments during voluntary diving in weddell seals. comparative biochemistry and physiology b 112, 361–375, doi: 10.1016/0305-0491(96)85239-4. hodanbosi m., sterba-boatwright b. & fahlman a. 2016. updating a gas dynamics model using estimates for california sea lions (zalophus californianus). respiratory physiology & neurobiology 234, 1–8, doi: 10.1016/j.resp.2016.08.006. hooker s.k., fahlman a., moore m.j., aguilar de soto n., bernaldo de quiros y., brubakk a.o., costa d.p., costidis a.m., dennison s., falke k.j., fernandez a., ferrigno m., fitz-clarke j.r., garner m.m., houser d.s., jepson p.d., ketten d.r., kvadsheim p.h., madsen p.t., pollock n.w., rotstein d.s., rowles t.k., simmons s.e., van bonn w., weathersby p.k., weise m.j., williams t.m. & tyack p.l. 2012. deadly diving? physiological and behavioural management of decompression stress in diving mammals. proceedings of the royal society b 279, 1041–1050, doi: 10.1098/rspb.2011.2088. houser d.s., howard r. & ridgway s. 2001. can diving-induced tissue supersaturation increase the chance of acoustically driven bubble growth in marine mammals? journal of theoretical biology 213, 183–195, doi: 10.1006/jtbi.2001.2415. huntington h.p. 2009. a preliminary assessment of threats to arctic marine mammals and their conservation in the coming decades. marine policy 33, 77–82, doi: 10.1016/j.marpol.2008.04.003. ivashkiv l.b. 2020. the hypoxia-lactate axis tempers inflammation. nature reviews immunology 20, 85–86, doi: 10.1038/s41577-019-0259-8. jefferson t.a., stacey p.j. & baird r.w. 1991. a review of killer whale interactions with other marine mammals: predation to co-existence. mammal review 21, 151–180, doi: 10.1111/j.1365-2907.1991.tb00291.x. jepson p.d., arbelo m., deaville r., patterson i.a.p., castro p., baker j.r., degollada e., ross h.m., herraez d., pocknell a.m., rodriguez f., howie f.e., espinosa a., reid r.j., jaber j.r., martin v., cunningham a.a. & fernandez a. 2003. gas-bubble lesions in stranded cetaceans. was sonar responsible for a spate of whale deaths after an atlantic military exercise? nature 425, 575–576, doi: 10.1038/425575a. jepson p.d., deaville r., patterson i.a.p., pocknell a.m., ross h.m., baker j.r., howie f.e., reid r.j., colloff a. & cunningham a.a. 2005. acute and chronic gas bubble lesions in cetaceans stranded in the united kingdom. veterinary pathology 42, 291–305, doi: 10.1354/vp.42-3-291. johnson m.p. & tyack p.l. 2003. a digital acoustic recording tag for measuring the response of wild marine mammals to sound. ieee journal of oceanic engineering 28, 3–12, doi: 10.1109/joe.2002.808212. kanatous s.b., davis r.w., watson r., polasek l., williams t.m. & mathieu-costello o. 2002. aerobic capacities in the skeletal muscles of weddell seals: key to longer dive durations? journal of experimental biology 205, 3601–3608. kato m. & hayashi r. 1999. effects of high pressure on lipids and biomembranes for understanding high-pressure-induced biological phenomena. bioscience, biotechnology, & biochemistry 63, 1321–1328, doi: 10.1271/bbb.63.1321. kayar s.r., aukhert e.o., axley m.j., homer l.d. & harabin a.l. 1996. lower decompression sickness risk in rats by intravenous injection of foreign protein. undersea & hyperbaric medicine 24, 329–335. king d.p & stott j.l. 2002. the cytokines of marine mammals: biological properties and molecular analysis. in c.j. pfeiffer (ed.): molecular and cell biology of marine mammals. pp. 289–299. malabar, fl: kreiger publishing coy. kingsle m.c.s., gosselin s. & sleno g.a. 2001. movements and dive behaviour of belugas in northern quebec. arctic 54, 262–275, doi: 10.14430/arctic786. kooyman g.l. 1973. respiratory adaptations in marine mammals. american zoologist 13, 457–468. kooyman g.l. & campbell w.b. 1972. heart rates in freely diving weddell seals, leptonychotes weddelli. comparative biochemistry and physiology a 43, 31–36. kooyman g.l., castellini m.a. & davis r.w. 1981. physiology of diving in marine mammals. annual review of physiology 43, 343–356, doi: 10.1146/annurev.ph.43.030181.002015. kooyman g.l. & ponganis p.j. 1998. the physiological basis of diving to depth: birds and mammals. annual review of physiology 60, 19–32, doi: 10.1146/annurev.physiol.60.1.19. kooyman g.l., wahrenbrock e.a., castellini m.a., davis r.w. & sinnett e.e. 1980. aerobic and anaerobic metabolism during voluntary diving in weddell seals: evidence of preferred pathways from blood chemistry and behavior. journal of comparative physiology 138, 335–346, doi: 10.1007/bf00691568. kovacs k.m., lydersen c., overland j.e. & moore s.e. 2011. impacts of changing sea-ice conditions on arctic marine mammals. marine biodiversity 41, 181–194, doi: 10.1007/s12526-010-0061-0. laidre k., hobbs r. & ferrero r. 2017. summer, fall, and early winter behavior of beluga whales, delphinapterus leucas, satellite-tagged in cook inlet, alaska, in 1999 and 2000. afsc processed report 2015–08. seattle, wa: alaska fisheries science center, national marine fisheries service, us dept. of commerce. lefebvre s.l., lesage v., michaud r. & humphries m.m. 2018. classifying and combining herd surface activities and individual dive profiles to identify summer behaviours of beluga (delphinapterus leucas) from the st. lawrence estuary, canada. canadian journal of zoology 96, 393–410, doi: 10.1139/cjz-2017-0015. macdonald a.g. 1982. hydrostatic pressure physiology. in p.b. bennet & d.h. elliot (eds.): the physiology and medicine of diving. pp 157–188. san pedro, ca: best publishing co. macdonald b.i. & ponganis p.j. 2013. insights from venous oxygen profiles: oxygen utilization and management in diving california sea lions. journal of experimental biology 216, 3332–3341, doi: 10.1242/jeb.085985. martin a.r., hall p. & richard p.r. 2001. dive behaviour of belugas (delphinapterus leucas) in the shallow waters of western hudson bay. arctic 54, 276–283, doi: 10.14430/arctic787. martin a.r. & smith t.g. 1992. deep diving in wild, free-ranging belugas whales, delphinapterus leucas. canadian journal of fisheries and aquatic sciences 49, 462–466, doi: 10.1139/f92-055. martin a.r. & smith t.g. 1999. strategy and capability of wild belugas, delphinapterus leucas, during deep, benthic diving. canadian journal of zoology 77, 1783–1793, doi: 10.1139/cjz-77-11-1783. martin a.r., smith t.g. & cox o.p. 1998. dive form and function in belugas delphinapterus leucas of the eastern canadian high arctic. polar biology 20, 218–228, doi: 10.1007/s003000050299. mcdonald b.i., johnson m. & madsen p.t. 2018. dive heart rate in harbour porpoises is influenced by exercise and expectations. journal of experimental biology 221, article no. jeb168740, doi: 10.1242/jeb.168740. mcintyre t. 2014. trends in tagging of marine mammals: a review of marine mammal biologging studies. african journal of marine science 36, 409–422, doi: 10.2989/1814232x.2014.976655. montcalm-smith e., caviness j., chen y. & mccarron r.m. 2007. stress biomarkers in a rat model of decompression sickness. aviation, space, & environmental medicine 78, 87–93. murphy k., travers p. & walport m. (eds.) 2008. janeway’s immunobiology. 7th edn. new york: garland science. noren s.r., kendall t., cuccurullo v. & williams t.m. 2012. the dive response redefined: underwater behavior influences cardiac variability in freely diving dolphins. journal of experimental biology 215, 2735–2741, doi: 10.1242/jeb.069583. noren s.r., poll c.p. & edwards m.s. 2018. body growth and rapid hematological development support breath hold of baby belugas (delphinapterus leucas) during subice transit. physiological & biochemical zoology 91, 691–704, doi: 10.1086/694920. noren s.r. & suydam r. 2016. navigating under sea ice promotes rapid maturation of diving physiology and performance in beluga whales. journal of experimental biology 219, 2828–2836, doi: 10.1242/jeb.143644. noren s.r. & williams t.m. 2000. body size and skeletal muscle myoglobin of cetaceans: adaptations for maximizing dive duration. comparative biochemistry and physiology a 126, 181–191, doi: 10.1016/s1095-6433(00)00182-3. nyquist p.a., dick e.j. jr. & buttolph t.b. 2004. detection of leukocyte activation in pigs with neurologic decompression sickness. aviation, space, and environmental medicine 75, 211–214. orr y., taylor j.m., cartland s., bannon p.g., geczy c. & kritharides l. 2007. conformational activation of cd11b without shedding of l-selectin on circulating human neutrophils. journal of leukocyte biology 82, 1115–1125, doi: 10.1189/jlb.0906545. padgett d.a. & glaser r. 2003. how stress influences the immune response. trends in immunology 24, 444–448, doi: 10.1016/s1471-4906(03)00173-x. ponganis p.j. 2015. diving physiology of marine mammals and seabirds. cambridge: cambridge university press. ponganis p.j. & williams c.l. 2015. oxygen stores and diving. in m.a. castellini & j.-a. mellish (eds.): marine mammal physiology: requisites for ocean living. pp 29–46. boca raton, fl: crc press. post e., alley r.b., christensen t.r., macias-fauria m., forbes b.c., gooseff m.n., iler a., kerby j.t., laidre k.l., mann m.e, olofsson j., stroeve j.c., ulmer f., virginia r.a. & wang m. 2019. the polar regions in a 2°c warmer world. science advances 5, article no. eaaw9883, doi: 10.1126/sciadv.aaw9883. pradillon f. & gaill f. 2007. pressure and life: some biological strategies. reviews in environmental science and bio/technology 6, 181–195, doi: 10.1007/978-1-4020-6285-8_21. richard p.r., martin a.r. & orr j.r. 1997. study of summer and fall movements and dive behaviour of beaufort sea belugas, using satellite telemetry: 1992–1995. environmental studies research funds 134. calgary: environmental studies research funds. richardson w.j. & wursig b. 1997. influence of man-made noise and other human actions on cetacean behaviour. marine and freshwater behaviour and physiology 29, 183–209, doi: 10.1080/10236249709379006. ridgway s.h., bowers c.a., miller d., schultz m.l., jacobs c.a. & dooley c.a. 1984. diving and blood oxygen in the white whale. canadian journal of zoology 62, 2349–2351, doi: 10.1139/z84-344. ridgway s.h., carder d.a. & clark w. 1975. conditioned bradycardia in the sea lion zalophus californianus. nature 256, 37–38, doi: 10.1038/256037a0. ridgway s.h. & howard r. 1979. dolphin lung collapse and intramuscular circulation during free diving: evidence from nitrogen washout. science 206, 1182–1183, doi: 10.1126/science.505001. romano t.a., olschowka j.a., felten s.y., quaranta v., ridgway s.h. & felten d.l. 2002. immune response, stress, and environment: implications for cetaceans. in c.j. pfeiffer (ed.): cell and molecular biology of marine mammals. pp. 253–279. malabar, fl: kreiger publishing co. schipke j.d., gams e. & kallweit o. 2006. decompression sickness following breath-hold diving. research in sports medicine 14, 163–178, doi: 10.1080/15438620600854710. schmitt t.l., st. aubin d.j., schaefer a.m. & dunn j.l. 2010. baseline, diurnal variations and stress induced changes of stress hormones in three captive beluga whales, delphinapterus leucas. marine mammal science 26, 635–647, doi: 10.1111/j.1748-7692.2009.00366.x. scholander p.f. 1940. experimental investigations on the respiratory function in diving mammals and birds. hvalrådets skrifter 22. oslo: jacob dybwad. shaffer s.a., costa d.p., williams t.m. & ridgway s.h. 1997. diving and swimming performance of white whales, delphinapterus leucas: an assessment of plasma lactate and blood gas levels and respiratory rates. journal of experimental biology 200, 3091–3099, doi: 10.1242/jeb.200.24.3091. somero g.n. 1992. adaptations to high hydrostatic pressure. annual review of physiology 54, 557–577, doi: 10.1146/annurev.physiol.54.1.557. stafford k.m., cita j.j., okkonen s.r. & suydam r.s. 2016. wind-dependent beluga whale dive behavior in barrow canyon, alaska. deep sea research part i 118, 57–65, doi: 10.1016/j.dsr.2016.10.006. st. aubin d.j., deguise s., richard p.r., smith t.r. & geraci j.r. 2001. hematology and plasma chemistry as indicators of health and ecological status in belugas whales, delphinapterus leucas. arctic 54, 317–331 doi: 10.14430/arctic791. suydam r.s., lowry l.f. & frost k.j. 2005. distribution and movements of beluga whales from the eastern chukchi sea stock during summer and early autumn. final report. ocs study mms 2005-035. accessed on the internet at http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.481.1445&rep=rep1&type=pdf on 25 august 2021. talpalar a.e. & grossman y. 2005. sonar versus whales: noise may disrupt neural activity in deep-diving cetaceans. undersea & hyperbaric medicine 32, 135–139. thompson l.a. & romano t.a. 2015. beluga (delphinapterus leucas) granulocytes and monocytes display variable responses to in vitro pressure exposures. frontiers in physiology 6, article no. 128, doi: 10.3389/fphys.2015.00128. thompson l.a. & romano t.a. 2016. pressure induced changes in adaptive immune function in belugas (delphinapterus leucas); implications for dive physiology and health. frontiers in physiology 7, article no. 442, doi: 10.3389/fphys.2016.00442. thompson l.a. & romano t.a. 2019. dive adaptation of beluga (delphinapterus leucas) immune system and implications for altered dive behavior. paper presented at the second international workshop on beluga whale research and conservation, 12–14 march, mystic, ct. thompson l.a., hindle g.a., black s.r. & romano t.a. 2020. variation in the hemostatic complement (c5a) responses to in vitro nitrogen bubbles in monodontids and phocids. journal of comparative physiology b 190, 811–822, doi: 10.1007/s00360-020-01297-y. tizard i.r. 2000. veterinary immunology: an introduction. 6th edn. philadelphia: w.b. saunders co. tyack p.l., johnson m., aquilar soto n., sturlese a. & madsen p.t. 2006. extreme diving of beaked whales. journal of experimental biology 209, 4238–4253, doi: 10.1242/jeb.02505. vacquie-garcia j., lydersen c. & kovacs k.m. 2019. diving behaviour of adult male white whales (delphinapterus leucas) in svalbard, norway. polar research 38, article no. 3605, doi: 10.33265/polar.v38.3605. wakeman l., al-ismail a., benton a., beddall a., gibbs a., hartnell s., morris k. & munro r. 2007. robust, routine haematology reference ranges for healthy adults. international journal of laboratory hematology 29, 279–283, doi: 10.1111/j.1365-2257.2006.00883.x ward c.a., mccullough d. & fraser w.d. 1987. relation between complement activation and susceptibility to decompression sickness. journal of applied physiology 62, 1160–1166, doi: 10.1152/jappl.1987.62.3.1160. watt c.a., orr j. & ferguson s.h. 2016. a shift in foraging behaviour of beluga whales delphinapterus leucas from the threatened cumberland sound population may reflect a changing arctic food web. endangered species research 31, 259–270, doi: 10.3354/esr00768. williams t.m., blackwell s.b., richter b., sinding m.h.s. & heide-jørgensen m.p. 2017. paradoxical escape responses by narwhals (monodon monoceros). science 358, 1328–1331, doi: 10.1126/science.aao2740. williams t.m., davis r.w., duiman l.a., francis j., boeuf b.j., horning m., calambokidis j. & croll d.a. 2000. sink or swim: strategies for cost-efficient diving by marine mammals. science 288, 133–136, doi: 10.1126/science.288.5463.133. williams t.m., fuiman l.a., kendall t., berry p., richter b., noren s.r., thometz n., shattock m.j., farrell e., stamper a.m. & davis r.w. 2015. exercise at depth alters bradycardia and incidence of cardiac anomalies in deep-diving marine mammals. nature communications 6, article no. 6055, doi: 10.1038/ncomms7055. wong r.m. 2006. decompression sickness in breath-hold diving, and its probable connection to the growth and dissolution of small arterial gas emboli. diving & hyperbaric medicine 36, 139–144, doi: 10.1016/j.mbs.2015.01.001. zimmer w.m.x. & tyack p.l. 2007. repetitive shallow dives pose decompression risk in deep-diving beaked whales. marine mammal science 23, 888–925, doi: 10.1111/j.1748-7692.2007.00152.x. stranded beluga (delphinapterus leucas) calf response and care: reports of two cases with different outcomes research article stranded beluga (delphinapterus leucas) calf response and care: reports of two cases with different outcomes caroline e.c. goertz,1 kathy woodie,1 brett long,1 lisa hartman,1 eric gaglione,2 dennis christen,2 tonya clauss,2 jennifer flower,3 allison tuttle,3 carey richard,3 tracy a. romano,3 todd schmitt,4 eric otjen,4 steve osborn,5 steve aibel,6 tim binder,6,7 william van bonn,6 manuel castellote,8,9 t. aran mooney,10 sophie dennison-gibby,11 kathy burek-huntington12 & teresa k. rowles13 1alaska sealife center, seward, ak, usa 2georgia aquarium, atlanta, ga, usa 3mystic aquarium, mystic, ct, usa 4seaworld san diego, san diego, ca, usa 5seaworld san antonio, san antonio, tx, usa 6john g. shedd aquarium, chicago, il, usa 7florida aquarium, tampa, fl, usa 8marine mammal laboratory, alaska fisheries science center, national oceanic and atmospheric administration, seattle, wa, usa 9cooperative institute for climate, ocean, and ecosystem studies, university of washington, seattle, wa, usa 10biology department, woods hole oceanographic institution, woods hole, ma, usa 11televet imaging solutions, pllc, oakton, va, usa 12alaska veterinary pathology service, eagle river, ak, usa 13marine mammal health and stranding response program, office of protected resources, national marine fisheries service, national oceanic and atmospheric administration, silver spring, md, usa abstract given the remote, rugged areas belugas typically inhabit and the low rehabilitation success rate with any cetacean, it is rare to have the opportunity to rescue a live-stranded beluga. the alaska sealife center cared for two stranded beluga calves with two different outcomes. in 2012, a neonatal male beluga calf (dl1202) stranded following intense storms in bristol bay. in 2017, a helicopter pilot discovered a stranded male beluga calf (dl1705) during a flight over cook inlet. the alaska sealife center transported both calves for rehabilitation and utilized supportive care plans based on those for other species of stranded cetaceans and care of neonatal belugas at zoological facilities. diagnostics included complete blood counts, serum chemistries, microbial cultures, hearing tests, imaging and morphometric measurements to monitor systemic health. treatments included in-pool flotation support; antimicrobials; gastrointestinal support; and close monitoring of respirations, urination, defecation and behaviour. after three weeks of supportive care, the bristol bay calf (dl1202) succumbed to sepsis secondary to a possible prematurity-related lack of passive transfer of antibodies. after seven weeks, the cook inlet calf (dl1705) recovered and all medications were discontinued. unable to survive on his own, he was declared non-releasable and placed in long-term care at a zoological facility, to live with other belugas. aspects and details from successful cases of cetacean critical care become important references especially vital for the survival of essential animals in small, endangered populations. this article is part of the special cluster beluga whales (delphinapterus leucas): knowledge from the wild, human care and tek, which has been funded by mystic aquarium, caff and the norwegian ministry of climate and environment. keywords cetacean; neonate; nutrition; hand-rearing; critical care abbreviations aep: audio evoked potentials aslc: alaska sealife center ci: cook inlet ct: computed tomography k2edta: potassium ethylenediaminetetraacetic acid mmhsrp: marine mammal health and stranding response program noaa: national oceanic and atmospheric administration rpm: rotations per minute sle: st. lawrence estuary   citation: polar research 2021, 40, 5514, http://dx.doi.org/10.33265/polar.v40.5514 copyright: polar research 2021. © 2021 goertz et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 29 november 2021 competing interests and funding: the authors report no conflict of interest. the aslc, georgia aquarium, mystic aquarium, seaworld, john g. shedd aquarium, the texas marine mammal stranding network and vancouver aquarium self-funded the cost of travel and salaries for their staff. additional funding was provided by the prescott grant program, prescott emergency grant program, seaworld busch gardens conservation fund and individual and corporate donations to the aslc center wildlife response programme. correspondence to: caroline e.c. goertz, alaska sealife center, po box 1329, seward, ak 99664, usa. e-mail: carrieg@alaskasealife.org to access the supplementary material, please visit the article landing page   introduction cetacean rehabilitation has a low success rate. over a 25-year period (1977–2002), out of 70 cetaceans that were stranded alive in california, 60 (86%) ultimately died. of the remaining animals, two (3%) were relocated and immediately released, five (7%) were rehabilitated and released, and three (4%) were declared non-releasable and placed in zoological facilities (zagzebski et al. 2006). a more recent review of the national mmhsrp catalogue listed 396 cetacean rescues from 2000 to 2016, with 294 (74%) ultimately dying or euthanized, 58 (15%) being released and 44 (11%) transferred to permanent zoological care (noaa fisheries mmhsrp national database unpubl. data); this shows an improved survival rate, from 14% in the earlier california data compared to 26% in the more recent review of the national database. there have been few attempts at rehabilitating belugas. given the remote, rugged areas belugas typically inhabit, it is rare to encounter and be able to coordinate the rescue of a live-stranded beluga. in the 1990s, there were unsuccessful attempts to rehabilitate beluga calves from the sle (de guise et al. 1992), all of which were either euthanized or died within 10 days (michaud et al. 2020). since that time, rescuers in sle have encountered three additional calves and reunited them with pods of sle belugas (michaud et al. 2020). because these calves were not tagged and were only followed for a few hours, it is unknown if they ultimately survived. a subadult sle beluga was discovered in poor condition upriver; supportive care was provided while the beluga was successfully translocated back to its normal range, tagged and released. this animal was tracked and re-spotted alive approximately one year later (le net et al. 2019). given the importance of the survival of each reproductive individual, rehabilitation efforts in threatened and endangered populations are also important. in addition, these cases provide valuable opportunities to better understand health threats to those populations as well as for refining medical and husbandry practices during the critical care period. ex situ options for cetacean conservation are receiving more attention with focused meetings on the topic (ex situ options for cetacean conservation workshop, nuremberg, 14–18 december 2018) and have been specifically considered for the vaquita (phocoena sinus; jaramillo‐legorreta et al. 2007) and the baiji (lipotes vexillifer; wang et al. 2006). the ci population of belugas (delphinapterus leucas) is listed as endangered and continues to decline for unknown reasons (nmfs 2008, 2016). with only 279 belugas as of the 2018 abundance estimate (shelden & wade 2019), every individual is essential to the population. despite the historical difficulties in rehabilitating cetaceans, the aslc in seward, alaska, attempted to rehabilitate a stranded beluga calf from bristol bay in 2012, as well as one from ci in 2017. one calf recovered and one succumbed. this report describes these two cases, including details of medical and husbandry care, diagnostic findings and additional factors that likely influenced the different outcomes for these two calves. methods stranding circumstances mid-afternoon on 18 june 2012, following a night of extreme storms and heavy surf, beach walkers observed a small beluga calf (dl1202) struggling at the water line, rolling in heavy surf close to south naknek, off bristol bay, alaska (58.72 n, 156.99 w). a rescue was authorized after unsuccessful attempts were made to return the animal to deeper water, and local observers confirmed the absence of any adult belugas in the area. the male calf was transported by a fixed wing aircraft and truck to aslc for attempted rehabilitation. mid-afternoon on 30 september 2017, a small beluga (dl1705) was observed above the waterline on trading bay, south of mcarthur river, on the west side of ci (60.88 n, 151.73 w), alaska, by an alaskan state trooper and noaa law enforcement in a helicopter. upon closer inspection, the beluga was determined to be a live calf with moderate external physical trauma. attempts to encourage the calf to swim into the inlet were unsuccessful, and adult belugas were not observed in the area during a subsequent overflight to pick up a veterinarian for an examination of the calf. the stranded beluga was assessed to be a dependent male calf with injuries deemed non-life-threatening, prompting recommendation for rehabilitation. rescue was authorized, and the calf was transported by helicopter and truck to aslc for attempted rehabilitation. aging animals were aged based on morphological characteristics and physiological parameters summarized in fig. 1 and table 1. fig. 1 physical attributes used to determine age in stranded beluga calves (delphinapterus leucas). dl1202 had (a) an umbilical sheath containing cord remnants and dark periocular pigmentation as well as (b) foetal folds. dl1705 did not have (c) an umbilical cord or sheath but did have (d) foetal folds and (e) dark periocular pigmentation. table 1 parameters used for aging the stranded beluga calves based on data and observations from beluga, other cetaceans and other mammalian neonates, as noted in the description. characteristic description (reference) dl1202, bristol bay dl1705, ci findings age (days) findings age (days) admission date beluga neonates have been photographed in ci as early as mid-july and as late as october (mcguire & stephens 2017) 18 june 2012 – 30 september 2017 – length beluga age estimated from length using formula: [51.5+(4.451 × tl)–(0.0106 × tl2)]–478 ±8.6 d (dalton 2007; robeck et al. 2015) 144 cm -5.4 (-14.0–3.2) 162 cm 16.4 (7.8–25.0) weight average 64 kg (55–65). smallest surviving beluga calf in zoological facilities was 53.6 kg (dalton 2007) 45.5 kg premature 64 kg full term meconium passage meconium, or foetal faeces, is typically passed within 1–3 days after birth in humans before transitioning to normal faeces (bekkali et al. 2008; lakshmanan & ross 2008) observed <3 not observed >3 umbilicus healing umbilical cord remnant present at birth, falls off ca. 1 week, healed at body wall ca. 3 weeks in bottlenose dolphins and harbour seals (phoca vitulin; dierauf et al. 1984; dearolf et al. 2000) cord present <3 no cord, healed at body wall, divot present >14 foetal folds skin indentations on flank due to compression in utero, smooth out by 2 months in bottlenose dolphins and beluga (dearolf et al. 2000; krasnov et al. 2009) present, pronounced <14 present, mild 7–21 flukes floppy/wrinkly flukes firm up by ca. 2 week in bottlenose dolphins (dearolf et al. 2000) soft, somewhat curved <14 firm, fairly flat >14 ‘black eye’—‘eye ring’ variably present for a couple of weeks for ‘black eye,’ several months for ‘eye ring’ in beluga (r. michaud, pers. comm.) present <60 present < 60 post-natal moult variable, occurs ca. 1–2 months post-parturition in beluga (s. aibel, pers. comm.) not observed, lanugo noted post-mortem <30 started 5 days post-admission 30–60 bilirubin hyperbilirubinemia seen in neonates due to liver immaturity and foetal haemoglobin turnover, more pronounced with prematurity, decreases with age, resolves in 1–2 weeks in harbour seals, bottlenose dolphins and harbour seals (dierauf et al. 1984; feinholz & atkinson 2000; morgan et al. 2009) 2.8 mg/dl <7 0.7 mg/dl >10 swim pattern uncoordinated, corking smooth arcs histopathology foetal structures premature not applicable na summary premature 2-day-old full-term 16-day-old housing and environmental parameters dl1202 was housed in an outdoor 6 m circular pool with a depth of up to 1.8 m (53 347 l). dl1705 was initially housed in an interior 4.6 m circular pool with a depth up to 1.2 m (20 013 l); this pool room had a large bay exterior door that was increasingly left open as time progressed to acclimate the calf to outdoor temperatures. after five weeks, dl1705 was transferred to an outdoor pool that could be managed at variable depths. initially, the calf was kept in an area that was a half-circle with a radius of about 4.6 m at 0.9 m deep. about two weeks later, the pool was reconfigured to allow access to a 16.1 m × 9.1 m oval mostly at 0.9 m but partially at 1.8 m deep. after another two weeks, the water level was raised to 1.8 m and then 2.7 m with a total capacity of 286 650 l. pools were supplied with natural seawater from wells passively filled during high tides from resurrection bay approximately 60 m below the surface and 210 m from the shore. once mechanically filtered, seawater was distributed to pools as needed. depending on the pool, water was set up to be flow through or was recirculated through skimmers at a rate to ensure a minimum of two complete turnovers daily. a combination of heated salt and fresh city water was added in a side stream to achieve the desired temperature, which ranged 15.6–21.7°c for dl1202 and 10.6 to 21.1°c for dl1705 while inside. pool salinity was monitored multiple times a day, and the relative flows of seawater and freshwater were adjusted as needed to keep the water at or above 24 ppt. after dl1705 was moved outside, supplementation of heated water was reduced and ultimately discontinued, and water temperature fluctuated with ambient conditions from 5.0 to 10.00°c. coliform testing was done weekly, consistent with animal welfare act requirements. additional measured parameters included water temperature and, when city water was being added, chlorine, ph and salinity. lighting was predominantly natural ambient light, supplemented with artificial sources for staff safety and during medical and husbandry procedures. outdoor pools were partially shaded by portions of the building and surrounding mountains. both calves were under strict quarantine, with their own dedicated staff and spaces. food preparation, area cleaning and equipment sanitation were consistent with animal welfare act standards. dl1705 cleared quarantine five weeks after admission following recovery from his presenting health problems and successfully passed screening tests for infectious diseases of concern. nutrition both calves initially received electrolytes, nutritional supplements and fluids mixed with increasing concentrations of artificial milk-replacer formula, ground herring and salmon oil (supplementary table s1) via orogastric intubation, which was based on a formula developed for hand-rearing neonatal beluga calves at zoological institutions when maternal care was insufficient (winhall 2012). the calves were lightly restrained, with just enough support to keep them stationary, and a foal feeding tube was passed orally to the stomach. using syringes, oral medications were mixed into a slurry and slowly injected down the tube, followed by calf feeding syringes of formula warmed to 35–37.7°c. while dl1202 was never successful at taking formula from a bottle, dl1705 quickly learned to voluntarily suckle from the tube, and subsequently, a bovine nipple on a bottle was utilized to deliver the formula without the need for any restraint. the initial voluntary feedings were inefficient, necessitating utilization of both methods until the calf could ingest enough from bottles to maintain an appropriate rate of weight gain with voluntary feeding alone. husbandry and veterinary care staffing for both calves included around the clock care by one to three people with extensive beluga, cetacean rehabilitation and/or neonatal cetacean experience; additional staff provided assistance for specific procedures or tasks as needed. the onsite care team was supported by consultants from zoological facilities that care for belugas, federal biologists and other medical and veterinary experts. the daily routine included body measurements, food preparation, multiple feedings, detailed animal monitoring and observational record keeping (including respiratory rate, defecations, behaviour and treatments), enrichment, pool parameter monitoring and cleaning. veterinary exams were initially done twice a day and later once a week with daily visual check-ins. various biological samples (blood, blowhole and breath, gastrointestinal contents and faeces, by techniques listed below), diagnostic images, body weights and other morphometric measurements were initially collected several times a week. as dl1705 stabilized, sample collection frequency decreased. both calves were treated with antibiotics, antifungals and gastrointestinal modifiers (supplementary table s2) using published doses (stoskopf et al. 2001), upon the recommendation of consulting veterinarians or based on published cases (reidarson et al. 2001; sweeney et al. 2010; osborn et al. 2012; winhall 2012; flower et al. 2018). sample collection, processing and storage following collection, samples were either analysed promptly as described below or transferred to appropriate containers and stored in a –80°c freezer until sent for further analysis typically within a few days to weeks unless otherwise noted. after the skin was disinfected with alcohol, blood was collected from the periarterial venous rete on the dorsal or ventral tail fluke using a 1.3 cm 19–21 gauge butterfly catheter (becton, dickinson & co.) directly into plain, serum separator, sodium heparin and k2edta vacutainer® tubes (bd biosciences); or, using a syringe, blood was immediately transferred into appropriate tubes. whole blood was kept at room temperature and analysed within 4 hr. plain and serum separator tubes were allowed to clot at room temperature, and then serum was separated by centrifugation for 5 min at 4000 rpm. serum biochemical analyses were performed, or serum was pipetted in 1 ml aliquots into cryovials for storage. sodium heparin and k2edta tubes were centrifuged for 5 min at 4000 rpm to separate plasma, which was pipetted in 1 ml aliquots into cryovials. swabs of the rectum, wounds, skin and blowhole were collected and placed in amies or cary-blair media (becton, dickinson & co.), refrigerated and sent within 24 hr to a commercial microbiology laboratory for microbial pathogen screening. additional swabs were collected and stored in viral transport media (remel microtest m4rt kit, medex supply) or were stored without media and frozen at –20°c until submitted for viral screening. respiratory cytology samples were obtained by holding a slide attached to a petri dish over the blowhole during multiple breaths. additional breath condensate was collected by holding a 50-ml conical tube or a petri dish with a nylon membrane attached over the blowhole for several breaths. gastric samples were collected using a feeding tube primarily prior to tubing fluids or formula but occasionally as a separate diagnostic sampling procedure. cytology slides of gastric samples were prepared immediately. additional samples were refrigerated at 4°c or frozen at –80°c. skin was collected when wound edges were trimmed, or opportunistically, as it fell off when moulting and transferred to cryovials. faecal samples obtained opportunistically and/or during enema treatments were transferred to cryovials. tissues from dl1202 collected for histopathology were preserved in 10% neutral buffered formalin and shipped to histology consulting services (everson, wa) for processing. paraffin-embedded sections were cut at 5 µm and stained with haematoxylin and eosin. laboratory analysis complete blood counts, serum chemistries and faecal parasite analyses were performed at aslc’s in-house clinical laboratory. two microhematocrit tubes were centrifuged for 6 min at 14 000 rpm to determine packed cell volume using a micro-capillary reader (international equipment company) and to aid in the identification of haemoparasites. blood smears were prepared, dried, fixed in methanol and stained using wright-giemsa (henry schein animal health) for manual white blood cell differential counts and to screen for haemoparasites. complete blood counts were performed on aslc’s idexx procyte dx (dl1705) or heska cbc diff (dl1202) analyser, using whole blood. serum chemistries were performed using aslc’s idexx vettest 8008, except for iron and triglycerides, which were run on the beckman coulter au480 chemistry analyzer at seaworld san diego’s in-house clinical laboratory. serum protein electrophoresis was run at the phoenix central laboratory on a helena protein electrophoresis unit. the concentration of serum cortisol was determined by a chemiluminescent-immunoassay (immulite, siemens healthcare diagnostics) at cornell university’s animal health diagnostic center; serum samples from dl1705 were submitted within weeks of collection, whereas those from dl1202 were submitted in 2019 for retrospective analysis and comparison to dl1705’s values. serum and molecular samples were shipped on dry ice via express delivery to reference laboratories and research facilities or testing for evidence of disease or exposure to avian influenza at the runstadler laboratory (spackman et al. 2002; puryear et al. 2016), brucella at mystic aquarium (meegan et al. 2010) and the university of illinois veterinary diagnostic laboratory (colegrove et al. 2016), herpesvirus at the university of florida zoological medicine and wildlife disease laboratory (davison et al. 2017), cetacean morbillivirus at athens veterinary diagnostic laboratory (saliki & lehenbauer 2001) and protozoal diseases (neospora caninum, toxoplasma gondii and sarcocystis neurona) at the university of california, davis (miller et al. 2002). culture swabs were submitted for aerobic bacterial culture at providence alaska medical center and athens veterinary diagnostic laboratory. tissue slides (dl1202 only) were examined by an american college of veterinary pathology board-certified pathologist with marine mammal experience (kbh, alaska veterinary pathology service), who provided histopathological diagnoses. imaging diagnostic thoracic and abdominal ultrasounds (e.i. medical imaging’s ibex pro and cl3.8l (2.5–5 mhz) and mc8.0 (6–10 mhz) transducers) were performed and used to serially measure and monitor blubber depth (cornick et al. 2016; dennison & saviano 2018). whole body ct scans were performed three times (12 october 2017, 16 november 2017 and 3 january 2018) for dl1705 for initial assessment and subsequent tracking to resolution of observed abnormalities. for ct, the calf was placed on foam and covered with moist sheets during scanning using a ge lightspeed16 ct scanner system. helical scan mode, 120 kv, 210 ma and pitch 1.75 were used for all studies. slice thickness varied between studies with 1.25 mm used initially and 5.00 mm subsequently. for all studies, images were reconstructed using a soft tissue and bone reconstruction algorithm. the entire process—removing the calf from his pool, transportation to the hospital, scanning, transportation back and return to his pool—was approximately 30 min. between ct scan dates, radiographic images were obtained from dl1705 using a minixray hf120/60hppwv powerplus generator, canon cxdi-70c wireless plate and vetrocket processing system. all ct and radiographic images were stored in dicom format and were reviewed by an american college of veterinary radiology board-certified radiologist with marine mammal experience (sdg, televet imaging solutions). hearing test hearing measurements were obtained only from dl1705 shortly after admission on 4–5 october 2017 and two months later on 5–6 december 2017 using aep recording methods (houser & finneran 2006; finneran et al. 2007; nachtigall et al. 2007; mooney et al. 2012). all hearing examinations were conducted in the water at a depth of 1 m, where the calf was gently held in place with its head freely moveable, similar to previously established methods with stranded and wild odontocetes (nachtigall 2005; castellote et al. 2014). data collection, calibrations and analyses were designed to follow that of previous beluga aep hearing studies and american national standards institute standards for measuring odontocete audiograms (castellote et al. 2014; ansi 2018; mooney et al. 2018; mooney et al. 2020). briefly, these methods included amplitude modulated tones played using a jaw phone to limit any effect of head movement. responses were measured from aep suction cup electrodes placed just behind the blowhole (positive recording electrode), on the dorsal ridge (reference) and a ground located on the animal’s caudal peduncle. responses were amplified 10 000× and filtered from 300 to 3000 hz. calibrations were conducted at 1 m at the location of the two hearing tests while the animal was not there. thresholds were determined using f-statistical methods. more details are presented by mooney et al. (2020). results following the admission exam on 18 june 2012 and a review of physical and physiological findings, dl1202 was assessed to be approximately two days old (fig. 1a, b, table 1) largely on the basis of the state of his umbilicus and the passage of meconium. additionally, being smaller than the smallest reported surviving calf in a zoological facility, prematurity was suspected. his swim pattern was initially uncoordinated, but he did not require assistance and over time he began to swim in smooth arcs through the water. his eyes were initially open and appeared normal; however, severe bilateral blepharospasm developed partway through his care precluding further voluntary examination. while he never successfully bottle-fed, he cooperated with his gavage feeds and initially gained weight (fig. 2). starting on 22 june 2012, he would sometimes float in a curved posture suggesting abdominal pain and had signs of constipation, delayed gastric emptying, gastrointestinal gas and increases in respiratory rate (fig. 3). the feeding formula was diluted, and medications were changed, which not only helped to mitigate these problems but also resulted in weight loss. fig. 2 daily weights (kg) in stranded beluga calves (delphinapterus leucas) dl1202 and dl1705. reference trend based on a median birth weight of 64 kg and an average weight gain of 0.32 kg per day of beluga calves born in aquaria (dalton 2007). fig. 3 average daily respiration rate (number of breaths over 5-min time periods taken frequently throughout the day, then averaged) in stranded beluga calves (delphinapterus leucas) dl1202 and dl1705. clinical laboratory findings included nonregenerative anaemia, neutrophilia, bilirubinaemia and elevated alkaline phosphatase (tables 2, 3, supplementary tables s3, s4). his initial beta and gamma globulins (table 4) were low, though later increased slightly. a high level of cortisol at admission decreased to a normal level but was elevated during one period of severe gastrointestinal distress and shortly before death (table 5). tests for exposure to diseases of concern were negative. outside of the periods of gastrointestinal distress, he would swim in a varied pattern using the whole pool, interacting with staff and enrichment items. table 2 summary haematology values in stranded beluga calves (delphinapterus leucas) dl1202 and dl1705. quartile ranges of values (25–75% quartiles around median) from 216 samples from 13 beluga of various ages residing at an aquarium are included for comparison (gulland et al. 2018). dl1202 (n = 8) dl1705 (n = 16) comparative values min max min max 25–75% quartiles rbca (106/mm3) 2.90 3.38 2.60 3.39 3.0 3.4 hbb (g/dl) 16.2 19.1 12.9 17.4 19.0 22.0 pcvc (%) 40 48 34 45 50 60 mcvd (fl) 133.7 144.7 121.7 137.2 163 185 mche (pg) 54.2 58.6 48.5 55.9 59 66 mchcf (g/dl) 40.5 42.6 38.3 41.0 36 38 platelets (103/mm3) 75 189 113 300 60 130 leukocytes/µl 3100 6500 2650 7820 5000 9500 neutrophil-band/µl 0 504 0 164 0 0 neutrophil/µl 2046 5850 1844 4848 2580 5520 lymphocyte/µl 0 637 504 2274 1100 4150 monocyte/µl 56 574 0 1329 220 780 eosinophil/µl 0 62 0 505 90 640 basophil/µl 0 0 0 115 0 0 nrbcsg 0 3 0 2 0 1 reticulocytes % 1.0 3.8 1.0 6.9 0.3 0.8 rdw % 24.7 26.8 13.6 20.1 not reported ared blood cells. bhaemoglobin. cpacked cell volume. dmean corpuscular volume. emean corpuscular haemoglobin. fmean corpuscular haemoglobin concentration. gnucleated red blood cells.   table 3 summary of serum chemistry values in stranded beluga calves (delphinapterus leucas) dl1202 and dl1705. quartile ranges of values (25–75% quartiles around median) from 216 samples from 13 beluga of various ages residing at an aquarium are included for comparison (gulland et al. 2018). dl1202 (n = 8) dl1705 (n = 16) comparative values min max min max 25–75% quartiles total protein (g/dl) 4.8 5.8 5.1 6.9 5.7 7.3 albumin (g/dl) 2.8 4.0 2.6 4.0 4.1 4.7 globulin (g/dl) 1.8 2.5 2.2 3.0 1.6 2.8 glucose (mg/dl) 53 114 57 116 84 124 buna (mg/dl) 32 59 36 74 47 59 creatinine (mg/dl) 0.6 1.6 0.4 0.9 1.2 1.6 bilirubin (mg/dl) 0.2 2.8 0.1 0.7 0.1 not reported cholesterol (mg/dl) 73 118 165 277 170 260 alk phosb (u/l) 221 522 165 588 100 220 altc (u/l) 17 36 10 51 3 10 astd (u/l) 89 146 50 131 45 80 ggte (u/l) 33 81 25 62 16 36 ckf (u/l) 75 285 92 289 80 180 ldhg (u/l) 752 1597 540 890 100 220 calcium (mg/dl) 9.1 10.3 8.9 11.2 9.1 10.6 phosphorus (mg/dl) 5.4 8.0 5.2 8.0 4.5 5.8 sodium (meq/l) 147 166 154 163 153 159 potassium (meq/l) 3.8 4.6 3.3 4.9 3.5 4.1 chloride (meq/l) 108 114 108 123 111 120 iron (mcg/dl) 108 133 60 701 195 380 amylase (u/l) 0 18 0 64 not reported triglycerides (mg/dl) 39 191 114 539 not reported ablood urea nitrogen. balkaline phosphatase. calanine transaminase. daspartate aminotransferase. egamma-glutamyl transferase. fcreatine kinase. glactate dehydrogenase.   table 4 serum protein electrophoresis values in stranded beluga calves (delphinapterus leucas) dl1202 and dl1705. comparative values were obtained from the isis/medarks/5.53 database (teare 1991), queried on 19 june 2012 for normal values (n = 1–6) from beluga calves less than 30 days old. id date age (days) tp (g/dl) alb (g/dl) alpha1 (g/dl) alpha2 (g/dl) beta (g/dl) gamma (g/dl) glob (g/dl) a:g dl1202 18 june 2012 2 5.2 3.1 0.7 1.2 0.2 0.1 2.1 1.45 23 june 2012 7 6.1 3.3 0.6 1.4 0.5 0.2 2.8 1.19 25 june 2012 9 5.3 3.0 0.5 1.4 0.4 0.1 2.3 1.28 27 june 2012 11 5.1 2.9 0.4 1.3 0.4 0.1 2.2 1.30 1 july 2012 15 5.1 2.9 0.4 1.3 0.3 0.1 2.2 1.33 4 july 2012 18 5.0 3.3 0.3 1.0 0.3 0.1 1.7 1.94 dl1705 30 september 2017 16 5.6 3.9 0.2 0.9 0.3 0.3 1.7 2.24 9 october 2017 25 5.8 4.1 0.2 1.0 0.3 0.1 1.7 2.37 18 october 2017 34 6.0 4.1 0.3 1.2 0.4 0.1 1.9 2.09 16 november 17 63 5.9 3.8 0.2 1.3 0.4 0.2 2.1 1.79 12 december 2017 89 6.0 3.9 0.3 1.3 0.4 0.2 2.1 1.87 15 february 2018 154 6.3 4.0 0.2 1.3 0.5 0.2 2.3 1.75 7 march 2018 174 6.3 4.1 0.3 1.2 0.4 0.3 2.2 1.91 comparative values <30 5.4–6.2 2.6–3.7 0.2–0.6 1.1 0.2–0.3 0.1–1.3 2.1–2.5 2.4–3.5   table 5 serum cortisol in stranded beluga calves (delphinapterus leucas) dl1202 and dl1705 and a baseline level obtained from adult beluga in a zoological facility (schmitt et al. 2010). calf id date estimated age (days) cortisol (ug/dl) dl1202 18 june 2012a 2 19.4 20 june 2012 4 9.07 23 june 2012 7 4.73 27 june 2012 11 19.4 1 july 2012 15 1.72 4 july 2012 18 4.14 8 july 2012 22 16.5 dl1705 30 september 2017a 16 11.600 4 october 2017 20 1.360 5 october 2017 21 1.010 9 october 2017 25 0.646 13 october 17 29 1.480 18 october 2017 34 2.630 22 october 2017 38 0.998 25 october 2017 41 0.780 29 october 2017 45 1.880 1 november 2017 48 0.754 7 november-2017 54 0.484 22 november 2017 69 2.080 12 decemeber 2017 89 0.637 9 january 2018 117 0.801 15 february 2018 154 1.580 7 march 2018 174 0.913 comparative values from an adult 1.8 ± 0.71 aadmission. during his last day, he appeared increasingly disoriented, vomited and appeared to be experiencing an episode of delayed gastric emptying with mild increased respiratory effort. while attempts were being made to relieve the build-up of undigested formula from his stomach, he developed respiratory distress, subsequently vomiting and aspirating formula. despite emergency therapy, the respiratory distress could not be reversed, and he succumbed on 8 july 2012. a necropsy was performed the following day, and findings included significant changes in multiple organs. bilateral roughened, inflamed ocular surfaces and corneal ruptures were accompanied by debris deep in the conjunctival fornix. there was a copious amount of serosanguinous fluid with fibrinous strands in the right hemithorax and pericardium as well as cloudy fluid in the abdomen. white fluffy material was adherent to the oesophagus. all sections of the gastrointestinal tract contained abundant digesta, without gaps, and were more than expected. histopathological analysis of the tissues indicated he likely developed septicaemia secondary to or in conjunction with ruptured corneas, pleuropneumonia, bronchopneumonia and pericarditis. in some areas, there were plugs of fibrin in many of the alveoli and foamy macrophages suggestive of poor ciliary escalator or partial obstructions to outflow. eosinophilic intranuclear inclusion bodies in the pharynx and tonsil as well as in the bone marrow were consistent with herpesvirus, though no further follow-up was pursued. findings also included severe ulcerative fungal pharyngitis, esophagitis and gastritis, likely secondary to required antibiotic treatments and the immunologically weakened condition of the animal. this animal had several tissues that appeared more immature than expected of a full-term neonate, including foetal glomeruli, with no adult forms and poorly formed muscularis externa of the colon and the jejunum, which likely contributed to difficulty with effective movement of digesta. there was a distinct extra layer to the stratum corneum, which most likely represents a layer shed during the post-natal ecdysis. following the admission exam on 30 september 2017 and a review of physical and physiological findings, dl1705 was assessed to be approximately 16 days old (fig. 1c, d, e, table 1) largely on the basis of his length. for the first 48 hours, he required flotation support provided by two staff members, and then only one before reliably swimming independently. by the third day, he was able to consume most of his formula through a bottle, but supplemental gavage feedings were required to maintain adequate weight gain of about 0.5 kg/day, which were continued until day 39. tracking weight gain (fig. 2) was initially complicated by the post-natal ecdysis (fig. 4) beginning on day 3, resulting in the loss of more than 1 kg of skin a day as well as episodes of constipation which began on day 5, though they were never as severe as dl1202. blubber depth initially decreased (fig. 5) but increased over time. fig. 4 (a) post-natal ecdysis of beluga calf (delphinapterus leucas) dl1750 shortly after admission on 5 october 2017; (b) roughened, cracked, damaged skin starting to slough off the calf on 12 october. fig. 5 blubber depths over time in a stranded beluga calf (delphinapterus leucas) dl1705 at multiple lateral (l) and dorsal (d) sites used to assess body condition in field projects (cornick et al. 2016), including the nuchal fat pad; anterior (1) and posterior (2) to the pectoral fin; mid-dorsal ridge (3); mid-abdomen (4); and pelvis (5). clinical laboratory findings included regenerative anaemia, neutropenia and elevated alkaline phosphatase (tables 2, 3, supplementary tables s3, s4). his initial beta and gamma globulins (table 4) were low but twice that of dl1202. cortisol at admission was high but only about half that of dl1202, quickly decreased to a normal level and did not significantly change afterwards (table 5). tests for exposure to diseases of concern were negative, except for herpesvirus, which was not of clinical significance. hearing tests in october and december (fig. 6) indicated that this beluga calf heard all frequencies tested (4–128 khz) and showed sensitive hearing (<70 db) for a wide range of frequencies (16–80 khz). these findings were reflective of a healthy odontocete auditory system similar to many healthy belugas from the bristol bay population, the only other published data set of healthy, wild marine mammal hearing (mooney et al. 2018). both measurements were similar, showing continued auditory health of the animal throughout the rehabilitation period. fig. 6 audiograms from beluga calf (delphinapterus leucas) dl1705, adapted from mooney et al. (2020). a ct scan on 12 october 2017 revealed peribronchial infiltrates suggestive of aspiration pneumonia (fig. 7a), granular material within the gastrointestinal tract potentially due to sand ingestion during stranding, and intracranial ventriculomegaly indicating mild hydrocephalus (fig. 7d). his behaviour and respiratory rate (fig. 3) changed significantly on 17 october 2017, when his pattern of actively swimming, diving and interacting with staff switched to having increased buoyancy, spending more time logging at the surface, less time interacting with caretakers and breathing more rapidly. these changes, initially attributed to gastrointestinal distress, were likely due to pneumothorax. this was not diagnosed until his second ct scan on 16 november 2017, which revealed a left-sided pneumothorax without evidence of tension (fig. 7b), resolution of the previous pneumonia and improved but not resolved intracranial ventriculomegaly. over time, clinical progress was observed as buoyancy decreased, respirations normalized and the pneumothorax spontaneously resolved, as demonstrated in the third ct scan (3 january 2018), which revealed (fig. 7c) no evidence of pneumothorax or pneumonia as well as resolution of the intracranial ventriculomegaly. fig. 7 select ct scans of stranded beluga calf (delphinapterus leucas) dl1705 (the patient’s left side is on the right side of the images): (a) peribronchial infiltrates (indicated by ovals) on 12 october 2017; (b) left-sided pneumothorax (p) on 16 november 2017; (c) resolved pneumonia and pneumothorax on 3 january 2018; (d) mild hydrocephalus (indicated by arrows) in the lateral ventricles seen on the initial scan of dl1705’s head, taken on 12 october 2017; the condition improved and finally resolved on subsequent scans. once the calf’s bloodwork and behaviour improved, antibiotics were discontinued on day 25 and antifungals on day 53, though he continued to remain on various gastrointestinal support medications because of recurring problems attributed to the artificial formula. when his activity increased, he needed more space and was moved outside on day 38. while dl1705 successfully recovered from its presenting problems, he was later deemed non-releasable after 97 days of care because of his inability to survive on his own and the risk of recurrence of his pneumothorax. on 9 may 2018, he was transferred to a zoological facility, to live with other belugas, for long-term care. discussion the trauma of the stranding event caused external physical injuries in both calves and likely resulted in pneumonia, a common complication in stranded cetaceans (bossart et al. 2013). the hard surface of a beach inhibits their chest expansion during inhalation, which can result over time in poor ventilation, carbon dioxide build-up, hypoxia, respiratory acidosis, sequestration of bacteria and, ultimately, poor vascular tissue circulation (geraci & lounsbury 1993; díaz-delgado et al. 2018; st. leger et al. 2018; fahlman et al. 2021). animals may strand in an unusual orientation, making it difficult for them to adequately raise the blowhole to avoid inhaling water. while an infectious disease likely caused their pneumonia, both calves were negative for diseases of concern (avian influenza, brucella spp. and morbillivirus) and their respiratory symptoms improved following antibiotic treatment. additionally, both animals suffered from various gastrointestinal issues, including constipation and gas, which were treated with a combination of formula adjustments adding water, probiotics, laxatives, anti-gas medicine, enzymes and enemas to aid in passage of contents, digestion of formula and minimization of gas build-up. at the time, these problems were attributed to the formula being artificial and the use of antibiotics, both of which can be associated with negative impacts to the gastrointestinal system, including bloat and malabsorption (seegraber & morrill 1986; bell et al. 2011; heinze et al. 2014; vangay et al. 2015; bayne & edmondson 2020). additionally, air was visibly introduced during tubing and was audibly being sucked in during nursing. however, dl1705 continued to have intermittent gastrointestinal issues even after antibiotic treatment was discontinued and was weaned to whole fish, suggesting that there may have been additional causes in his case. dl1202’s greatest challenges likely stemmed from his young age at stranding, minimal time spent with his mother and his apparent prematurity. the calf’s age estimate and assumed prematurity were supported by the original morphological observations, serum chemistry results, behaviour and post-mortem analysis of tissues (table 1). based on the initial exam and diagnostic test results, we suspected that dl1202 never nursed and, therefore, did not receive colostrum, containing maternal antibodies. because cetaceans have epitheliochorial placentation, which prevents the pre-partum transfer of antibodies, this calf was immunocompromised (ruiz et al. 2009). this failure of passive transfer predisposes neonates such as dl1202 to life-threatening infections (tizard 1992; lebert et al. 2017), such as the pathogens associated with his pleuropneumonia, pericarditis, bronchopneumonia and gastrointestinal fungal infections. while no overt signs of stress were observed during the time in rehabilitation, retrospective analysis of dl1202’s serum indicated elevated cortisol (table 5), distinctly higher than dl1705’s, whose cortisol, while elevated upon admission after stranding, quickly decreased to, and remained at, levels (0.637–2.630 ug/dl) similar to baseline levels (1.80 ± 0.71 ug/dl) in adult belugas in a zoological facility (schmitt et al. 2010). with the benefit of retrospect, dl1202’s recovery was always less likely than dl1705, though not impossible. rehabilitating cetacean stranders is always an uphill battle and gets harder and harder the younger they are. post-mortem analysis of dl1202’s tissues indicated that he was even more premature than initially assumed and had a severe lack of passively acquired antibodies. in light of the particular challenges imposed by this prematurity, the benefits of more aggressive antimicrobial therapy and gastrointestinal support likely would have outweighed the risks of complications, improving his odds of survival. these findings informed our treatment of dl1705, allowing the team to pursue such therapeutic options more confidently. some of dl1705’s unique medical concerns included an early natal ecdysis, hydrocephalus and spontaneous pneumothorax. beluga calves undergo a post-natal ecdysis or moult at 2–4 months of age (pers. comm., s. aibel), losing the entire layer of neonatal skin, revealing smooth, intact skin underneath, similar to that seen in southern right whales (eubalaena australis; reeb et al. 2005). less than a week after admission at less than a month of age, dl1705 began sloughing centimetre-thick skin, more than a kilogram a day for several days (fig. 4). the underlying, newly exposed skin was rough and developed fissures that extended to just above the blubber, suggesting that the skin was not mature. in this case, the ecdysis may have been accelerated by the abrupt change in his physical environment, which included warmer, less saline water, conditions that appear to cause dermatological changes in beluga and other cetaceans (st. aubin et al. 1990; duignan et al. 2020; pitman et al. 2020). physical trauma by the stranding event, susceptibility of cetacean skin to dehydration (oh et al. 2015; st. leger et al. 2018) and the impact of stress on skin condition (peters 2016) would have further contributed to skin damage. fortunately, none of the fissures exposed blubber or muscle, and within a few weeks, the thin damaged outermost layer peeled away, revealing smooth, healthy skin. ct scans were originally pursued to better assess, track and make treatment decisions regarding dl1705’s pneumonia; however, they also revealed two subclinical medical conditions. in addition to pneumonia, the first scan revealed an accumulation of cerebrospinal fluid within the brain, also known as hydrocephalus. this condition can be due to an obstruction caused by congenital defects, infectious diseases, exposure to toxins, other conditions that impair the normal flow or excessive production (de stefani et al. 2011; biel et al. 2013). in cetaceans, hydrocephalus has been associated with brucella spp. infection (st. leger 2007; langan 2016), but congenital hydrocephalus has also been reported in a bottlenose dolphin (tursiops truncates; corpa et al. 2004) born at a zoological facility where the dolphins were healthy, but testing for brucella spp. was not pursued. dl1705 tested negative for exposure to brucella spp. on both serological and molecular assays. dl1705’s hydrocephalus was mild and reduced in size in subsequent scans, suggesting a transient cause, an anatomic anomaly that became less significant as he grew, or a normal variant in beluga calves of that age. the second ct scan revealed a pneumothorax, which is an abnormal collection of air in the pleural space between the lung and the chest wall that results in collapse of lung tissue. causes include trauma, iatrogenic complications of medical intervention (i.e., biopsy or needle insertion) and lung disease, or it may occur spontaneously, and can result in chest pain, shortness of breath and a decrease in respiratory efficiency (zarogoulidis et al. 2014). this condition has been previously reported in cetaceans in association with pulmonary abscesses, fine-needle aspirations and stranding events and can also occur without an identifiable cause (mueller & geraci 1977; brouwer 1981; walsh & gearhart 2001; reidarson 2007; langan 2009; fernández et al. 2017; díaz-delgado et al. 2018). in afflicted cetaceans, a pneumothorax often results in an abnormal swimming orientation due to altered buoyancy, and they float with the affected side up (walsh & gearhart 2001). however, dl1705 did not list to one side and continued to float evenly in the water column. in retrospect, there were clinical signs consistent with a pneumothorax that were originally attributed to other problems. between the first two ct scans, the calf had become increasingly positively buoyant, riding higher in the water column, consistent with the collection of excessive gas in the gastrointestinal system. this was suspected to be associated with digestive difficulties with the artificial formula and aerophagia resulting from the calf’s inefficient suckling. also, during this time, an increased respiratory rate (fig. 3) was attributed to the pain associated with colic but was likely associated with the altered respiratory ability. following the pneumothorax, on auscultation, there was a notable difference when listening to the affected versus the unaffected lung, which decreased over time and coincided with the body’s reabsorption of the air in the pleural space. a specific inciting cause of dl1705’s pneumothorax was not identified, and it resolved without treatment. however, if the pneumothorax were to recur, this could affect the calf’s ability to dive (reidarson 2007) and catch food, which was one of the factors that contributed to the non-releasable designation. dl1705’s audiogram overlapped with bristol bay beluga audiograms and was similar to captive belugas with ‘normal’ hearing (mooney et al. 2018; mooney et al. 2020), suggesting this animal also had ‘normal’ hearing similar to many other belugas. initial data impressions indicated that the animal did hear well from 4 to 128 khz and was particularly sensitive to sounds at 54 and 80 khz. the animal also heard lower frequencies (4–16 khz) reasonably well. he seemingly did not hear as high in frequency as some bristol bay belugas, but a large portion of that population also only hears up to 120–128 khz (or lower), similar to dl1705. this range of hearing and its overall sensitivity would suggest the animal could hear communication signals well. it would also be able to detect natural and anthropogenic sounds. the october and december hearing test results were similar, reflecting the consistency of the method and the stability of the animal’s hearing. the two acoustic test results were similar despite moving the tests from the indoor to the outdoor pool, suggesting that both locations provide similar and good locations for a stranded animal’s auditory health. hearing and acoustics are the primary means that belugas and other odontocetes communicate and investigate their surroundings (au 1993, 2000); sounds are key to many natural beluga behaviours and interactions (schevill 1949; sjare & smith 1986). the ‘good’ auditory results for dl1705 imply that the animal should develop normally with respect to acoustic behaviour and sensory biology. after five weeks of care, dl1705 was doing well enough to be taken off antibiotics and moved to an outdoor pool enclosure. following a formal process by noaa fisheries, he was designated non-releasable because of his nutritional and social dependency on human care as well as the risk of recurrence of pneumothorax. a cause for dl1705’s stranding has not been determined as there was no evidence of pre-existing disease or trauma, and he was in reasonable body condition. the calf continues to have periodic gastrointestinal motility disorder, and it is possible that he has an undiagnosed congenital or developmental problem. being a full-term calf, physically and immunologically robust, likely contributed to dl1705’s successful recovery from problems associated with stranding. early medical intervention with broader spectrum, more powerful antibiotics, antifungals, fluids and nutritional supplementation, without waiting for the identification of specific pathogens or specific diagnosis, likely also contributed to case success. familiarity with nursing may have contributed to the calf quickly adapting to bottle feeding, which reduced the need for, and risks associated with, frequent tubing. finally, the experience of the first case and the depth of expertise of the team made it possible to identify and mitigate problems early. conclusions these cases provided a wealth of information on the beluga populations that the calves originate from and novel information about wild beluga neonates, and produced several notable achievements. both cases provided the opportunity to investigate diseases of concern (avian influenza, brucella spp., herpesvirus, cetacean morbillivirus, neospora caninum, toxoplasma gondii and sarcocystis neurona) as well as closely track several physiologic and metabolic parameters of beluga neonates. dl1705 was the first wild beluga calf, and the first beluga from the endangered ci population, to have a hearing test. additionally, dl1705 provided a unique opportunity to look at beluga calf neonatal anatomy via ct scan and to track changes in skin over time. while dl1202 was the first stranded beluga calf to be cared for in alaska and survived longer than any other recorded case in the world at the time, dl1705 was the first successful rehabilitation of a stranded beluga calf. once thought to be close to impossible, these cases demonstrate the ability to care for and, in dl1705’s case, rehabilitate stranded beluga calves, providing another tool to assist in the conservation of endangered populations. approvals and permits these efforts were carried out in accordance with the requirements of the aslc-noaa/national marine fisheries service stranding agreement and noaa’s mmhsrp marine mammal protection act/endangered species act #18786-02. animal care and data gathering protocols were developed by aslc veterinarians and reviewed and approved by noaa fisheries staff and veterinarians. acknowledgements the authors thank the dedicated animal care and veterinary staff from the aslc, georgia aquarium, mystic aquarium, seaworld, john g. shedd aquarium, the texas marine mammal stranding network and vancouver aquarium, who provided direct support, advice and funds for the care of these beluga calves. the authors further thank numerous colleagues who shared their clinical experiences and knowledge of neonatal cetacean care; scientific advisors who provided rapid feedback on diagnostic results at no cost; and noaa personnel who facilitated specific health assessments and managed the decision regarding releasability. this constitutes scientific manuscript contribution #298 from the sea research foundation, inc. references ansi (american national standards institute) 2018. procedure for determining audiograms in toothed whales through evoked potential methods. melville, ny: american national standards institute. au w. 1993. the sonar of dolphins. new york: springer. au w. 2000. hearing in whales and dolphins: an overview. in w. auet al. (eds.): hearing by whales and dolphins. pp. 1–42. new york: springer. bayne j.e. & edmondson m.a. 2020. diseases of the gastrointestinal system. in d. pughet al. (eds.): sheep, goat, and cervid medicine. 3rd edn. pp. 63–96. philadelphia, pa: elsevier. bekkali n., hamers s.l., schipperus m.r., reitsma j.b., valerio p.g., van toled, l. & benninga m.a. 2008. duration of meconium passage in preterm and term infants. archive of disease in childhood—fetal neonatal edition 93, f376–f379, doi: 10.1136/adc.2009.159442. bell k.m., rutherfurd s.m., cottam y.h. & hendriks w.h. 2011. evaluation of two milk replacers fed to hand-reared cheetah cubs (acinonyx jubatus): nutrient composition, apparent total tract digestibility, and comparison to maternal cheetah milk. zoo biology 30, 412–426, doi: 10.1002/zoo.20344. biel m., kramer m., forterre f., jurina k., lautersack o., failing k. & schmid m.j. 2013. outcome of ventriculoperitoneal shunt implantation for treatment of congenital internal hydrocephalus in dogs and cats: 36 cases (2001–2009). journal of the american veterinary medical association 242, 948–958, doi: 10.2460/javma.242.7.948. bossart g.d., hurley w., biedenbach g., denny m., borkowski r., goricki c., searcy e., roberts k. & reif j. 2013. pathologic findings in stranded cetaceans from northeastern florida. the journal of infectious diseases 1, 36–50. brouwer l. 1981. subcutaneous emphysema in a beluga whale. paper presented at the 12th annual conference of the international association for aquatic animal medicine, 3–6 may, mystic, ct. castellote m., mooney t.a., quakenbush l., hobb, r., goertz c. & gaglione e. 2014. baseline hearing abilities and variability in wild beluga whales (delphinapterus leucas). journal of experimental biology 217, 1682–1691, doi: 10.1242/jeb.093252. colegrove k., venn-watson s., litz j., kinsel m., terio k., fougeres e., ewing r., pabst d., mclellan w., raverty s., saliki j., fire s., rappucci g., bowen-stevens s., noble l., costidis a., barbieri m., field c., smith s., carmichael r.h., chevis c., hatchett w., shannon d., tumlin m., lovewell g., mcfee w. & rowles t.k. 2016. fetal distress and in utero pneumonia in perinatal dolphins during the northern gulf of mexico unusual mortality event. diseases of aquatic organisms 119, 1–16, doi: 10.3354/dao02969. cornick l.a., quakenbush l.t., norman s.a., pasi c., maslyk p., burek k.a., goertz c.e.c. & hobbs r.c. 2016. seasonal and developmental differences in blubber stores of beluga whales in bristol bay, alaska using high-resolution ultrasound. journal of mammalogy 97, 1238–1248, doi: 10.1093/jmammal/gyw074. corpa j.m., peris b., palacio j., liste f. & ribes v. 2004. hydrocephalus in a newborn bottlenosed dolphin (tursiops truncatus). veterinary record 155, 208–210, doi: 10.1136/vr.155.7.208. dalton l. 2007. reproductive biology of the beluga whale (delphinapterus leucas). paper presented at the 38th annual conference of the international association for aquatic animal medicine, 5–9 may, orlando, fl. davison a.j., nielsen o., subramaniam k., jacob j.m., romero c.h., burek-huntington k.a. & waltzek t.b. 2017. genome sequence of an alphaherpesvirus from a beluga whale (delphinapterus leucas). genome announcements 5, e01100-17, doi: 10.1128/genomea.01100-17. dearolf j.l., mclellan w.a., dillaman r.m., frierson d. & pabst d.a. 2000. precocial development of axial locomotor muscle in bottlenose dolphins (tursiops truncatus). journal of morphology 244, 203–215, doi: 10.1002/(sici)1097-4687(200006)244:3<203::aid-jmor5>3.0.co;2-v. de guise s., giard j., patenaude r., michaud r., ramirez k., beland p., turgeon p., pelletier e. 1992. rescue of a newborn beluga whale in the st. lawrence estuary, quebec, canada. paper presented at the conference of the international association for aquatic animal medicine, 18–22 may, hong kong. dennison s. & saviano p. 2018. diagnostic imaging. in f.m.d. gullandet al. (eds.): crc handbook of marine mammal medicine. 3rd edn. pp. 537–551. boca raton, fl: crc press. de stefani a., de risio l., platt s.r., matiasek l., lujan-feliu-pascual a. & garosi l.s. 2011. surgical technique, postoperative complications and outcome in 14 dogs treated for hydrocephalus by ventriculoperitoneal shunting: ventriculoperitoneal shunting in dogs. veterinary surgery 40, 183–191, doi: 10.1111/j.1532-950x.2010.00764.x. díaz-delgado j., fernández a., sierra e., sacchini s., andrada m., vela a.i., quesada-canales ó., paz y., zucca d., groch k. & arbelo m. 2018. pathologic findings and causes of death of stranded cetaceans in the canary islands (2006–2012). plos one 13, e0204444, doi: 10.1371/journal.pone.0204444. dierauf l.a., dougherty s.a. & baker b. 1984. neonatal hyperbilirubinemia in harbor seals (phoca vitulina richardsi). journal of zoo and wildlife medicine 15, 55–59, doi: 10.2307/20094685. duignan p.j., stephens n.s. & robb k. 2020. fresh water skin disease in dolphins: a case definition based on pathology and environmental factors in australia. nature scientific reports 10, article no. 21979, doi: 10.1038/s41598-020-78858-2 fahlman a., brodsky m., rocho-levine j., garcia-parraga d., ivančić m., camarena c., ibarra l. & rocabert j. 2021. respiratory changes in stranded bottlenose dolphins (tursiops truncatus). journal of zoo and wildlife medicine 52, 49–56, doi: 10.1638/2020-0033. feinholz d.m. & atkinson s. 2000. possible aetiologies of yellow coloration in dolphin calves. aquatic mammals 26, 191–195. fernández a., sierra e., díaz-delgado j., sacchini s., sánchez-paz y., suárez-santana c., arregui m., arbelo m. & de quirós y.b. 2017. deadly acute decompression sickness in risso’s dolphins. nature scientific reports 7, article no. 13621, doi: 10.1038/s41598-017-14038-z. finneran j.j., houser d.s. & schlundt c.e. 2007. objective detection of bottlenose dolphin (tursiops truncatus) steady-state auditory evoked potentials in response to am/fm tones. aquatic mammals 33, 43–54. flower j.e., langan j.n., nevitt b.n., chinnadurai s.k., stacey r., ivančić m. & adkesson m.j. 2018. neonatal critical care and hand-rearing of a bottlenose dolphin (tursiops truncatus) calf. aquatic mammals 43, 482–490, doi: 10.1578/am.44.5.2018.482. geraci j.r. & lounsbury v.j. 1993. marine mammals ashore: a field guide for strandings. galveston: sea grant college program, texas a&m university. gulland f.m.d., dierauf l.a. & whitman, k.l. 2018. normal hematology and serum chemistry ranges. in f.m.d. gullandet al. (eds.): crc handbook of marine mammal medicine. 3rd edn. pp. 1002–1029. boca raton, fl: crc press. heinze c.r., freeman l.m., martin c.r., power m.l. & fascetti a.j. 2014. comparison of the nutrient composition of commercial dog milk replacers with that of dog milk. journal of the american veterinary medical association 244, 1413–1422, doi: 10.2460/javma.244.12.1413. houser d.s. & finneran j.j. 2006. variation in the hearing sensitivity of a dolphin population determined through the use of evoked potential audiometry. the journal of the acoustical society of america 120, 4090–4099, doi: 10.1121/1.2357993. jaramillo‐legorreta a., rojas‐bracho l., brownell r.l., read a.j., reeves r.r., ralls k. & taylor b.l. 2007. saving the vaquita: immediate action, not more data. conservation biology 21, 1653–1655, doi: 10.1111/j.1523-1739.2007.00825.x. krasnov v.v., bel’kovich v.m. & chernetskii a.d. 2009. formation of behavior in the white sea beluga calf, delphinapterus leucas, during early postnatal ontogenesis. russian journal of marine biology 35, 53–59, doi: 10.1134/s1063074009010088. lakshmanan j. & ross m.g. 2008. mechanism(s) of in utero meconium passage. journal of perinatology 28 (suppl. 3), s8–s13, doi: 10.1038/jp.2008.144. langan j.n. 2009. diagnosis and management of a pulmonary abscess in a bottlenose dolphin (tursiops truncatus). paper presented at the 40th annual conference of the international association for aquatic animal medicine, 2–6 may, san antonio, tx. langan j.n. 2016. antemortem diagnosis of hydrocephalus and hearing loss associated with chronic brucella infection in a stranded rehabilitated bottlenose dolphin (tursiops truncatus). paper presented at the conference of the international association for aquatic animal medicine, 21–26 may, virginia beach, va. lebert c., mcgrew s., venn-watson s., dold c., nollens h. & jensen e. 2017. evaluation of rapid pool-side tests for diagnosis of failure of passive transfer in bottlenose dolphin (tursiops truncatus) neonates. paper presented at the 48th annual conference of the international association for aquatic animal medicine, 20–24 may, cancun, mexico. le net r., couture é., lasby b., wimmer t., haulena m., lair s., giard j., michaud r., binder t., elliott i. & lesage v. 2019. medical aspects of the translocation to the st. lawrence estuary (quebec, canada) of a beluga (delphinapterus leucas) trapped in a river. paper presented at the second international workshop on beluga whale research and conservation, 12–14 march, mystic, ct. mcguire t. & stephens a. 2017. photo-identification of beluga whales in cook inlet, alaska: summary and synthesis of 2005–2015 data. anchorage: lgl alaska research associates, inc. meegan j., field c., sidor i., romano t., casinghino s., smith c.r., kashinsky l., fair p.a., bossart g., wells r. & dunn j.l. 2010. development, validation, and utilization of a competitive enzyme-linked immunosorbent assay for the detection of antibodies against brucella species in marine mammals. journal of veterinary diagnostic investigation 22, 856–862, doi: 10.1177/104063871002200603. michaud r., giard j., michaud a. & moisan m. 2020. translocation of live-stranded newborn st. lawrence estuary belugas (delphinapterus leucas) for adoption by nearby females: a review of past responses, and assessment of feasibility and risks. tadoussac, qc: fisheries and oceans canada, canadian science advisory secretariat. miller m.a., gardner i.a., packham a., mazet j.k., hanni k.d., jessup d., estes j., jameson r., dodd e., barr b.c., lowenstine l.j., gulland f.m. & conrad p.a. 2002. evaluation of an indirect fluorescent antibody test (ifat) for demonstration of antibodies to toxoplasma gondii in the sea otter (enhydra lutris). journal of parasitology 88, 594–599, doi: 10.2307/3285456. mooney t.a., castellote m., jones i., rouse n., rowles t., mahoney b. & goertz c.e.c. 2020. audiogram of a cook inlet beluga whale (delphinapterus leucas). the journal of the acoustical society of america 148, 3141–3148, doi: 10.1121/10.0002351. mooney t.a., castellote m., quakenbush l., hobb, r., gaglione e. & goertz c. 2018. variation in hearing within a wild population of beluga whales (delphinapterus leucas). journal of experimental biology 221, jeb171959, doi: 10.1242/jeb.171959. mooney t.a., yamato m. & branstetter b.k. 2012. hearing in cetaceans: from natural history to experimental biology. advances in marine biology 63, 197–246, doi: 10.1016/b978-0-12-394282-1.00004-1. morgan l.w., jakush j.l., simpson a., norman m.m., pabst d.a. & simmons s. 2009. evaluation of hematologic and biochemical values for convalescing seals from the coast of maine. journal of zoo and wildlife medicine 40, 421–429, doi: 10.1638/2007-0032.1. mueller r. & geraci j.r. 1977. unusual disease findings in a stranded pilot whale. paper presented at the conference of the international association for aquatic animal medicine, 18–21 april, boston, ma. nachtigall p.e. 2005. hearing measurements from a stranded infant risso’s dolphin, grampus griseus. journal of experimental biology 208, 4181–4188, doi: 10.1242/jeb.01876. nachtigall p.e., mooney t.a., taylor k.a. & yuen m.m.l. 2007. hearing and auditory evoked potential methods applied to odontocete cetaceans. aquatic mammals 33, 6–13, doi: 10.1578/am.33.1.2007.6. national marine fisheries service 2008. endangered and threatened species; endangered status for the cook inlet beluga whale. federal register 73, 62919–62930. national marine fisheries service 2016. recovery plan for the cook inlet beluga whale (delphinapterus leucas). juneau, ak: national marine fisheries service, alaska region, protected resources division. oh j.w., chung o., cho y.s., macgregor g.r. & plikus m.v. 2015. gene loss in keratinization programs accompanies adaptation of cetacean skin to aquatic lifestyle. experimental dermatology 24, 572–573, doi: 10.1111/exd.12756. osborn s., dalton l., dold c. & robeck t. 2012. management of twin pregnancy and perinatal concerns in a beluga (delphinapterus leucas). journal of zoo and wildlife medicine 43, 193–196, doi: 10.1638/2011-0161.1. peters e.m.j. 2016. stressed skin?—a molecular psychosomatic update on stress-causes and effects in dermatologic diseases. journal der deutschen dermatologischen gesellschaft 14, 233–252, doi: 10.1111/ddg.12957. pitman r.l., durban j.w., joyce t., fearnbach h., panigada s. & lauriano g. 2020. skin in the game: epidermal molt as a driver of long‐distance migration in whales. marine mammal science 36, 565–594, doi: 10.1111/mms.12661. puryear w.b., keogh m., hill n., moxley j., josephson e., davis k.r., bandoro c., lidgard d., bogomolni a., levin m., lang s., hammill m., bowen d., johnston d.w., romano t., waring g. & runstadler j. 2016. prevalence of influenza a virus in live-captured north atlantic gray seals: a possible wild reservoir. emerging microbes & infections 5, e81, doi: 10.1038/emi.2016.77. reeb d., duffield m. & best p.b. 2005. evidence of postnatal ecdysis in southern right whales (eubalaena australis). journal of mammalogy 86, 131–138, doi: 10.1644/1545-1542(2005)086<0131:eopeis>2.0.co;2. reidarson t.h. 2007. air third spacing phenomena in two cetaceans. paper presented at the 38th annual conference of the international association for aquatic animal medicine, 5–9 may, orlando, fl. reidarson t.h., mcbain j.f. & yochem p.k. 2001. medical and nutritional aspects of a rehabilitating california gray whale calf. aquatic mammals 27, 215–221. robeck t.r., schmitt t.l. & osborn s. 2015. development of predictive models for determining fetal age-at-length in belugas (delphinapterus leucas) and their application toward in situ and ex situ population management. marine mammal science 31, 591–611, doi: 10.1111/mms.12180. ruiz c.l., nollens h.h., venn-watson s., green l.g., wells r.s., walsh m.t., nolan e.c., mcbain j.f. & jacobson e.r. 2009. baseline circulating immunoglobulin g levels in managed collection and free-ranging bottlenose dolphins (tursiops truncatus). developmental & comparative immunology 33, 449–455, doi: 10.1016/j.dci.2008.09.002. saliki j.t. & lehenbauer t.w. 2001. monoclonal antibody-based competitive enzyme-linked immunosorbent assay for detection of morbillivirus antibody in marine mammal sera. journal of clinical microbiology 39, 1877–1881, doi: 10.1128/jcm.39.5.1877-1881.2001. schevill w.e. 1949. underwater listening to the white porpoise (delphinapterus leucas). science 109, 143–144, doi: 10.1126/science.109.2824.143. schmitt t.l., st. aubin d.j., schaefer a.m. & dunn j.l. 2010. baseline, diurnal variations, and stress-induced changes of stress hormones in three captive beluga whales, delphinapterus leucas. marine mammal science 26, 635–647, doi: 10.1111/j.1748-7692.2009.00366.x. seegraber f.j. & morrill j.l. 1986. effect of protein source in calf milk replacers on morphology and absorptive ability of small intestine. journal of dairy science 69, 460–469, doi: 10.3168/jds.s0022-0302(86)80424-6. shelden k.e.w. & wade p.r. 2019. aerial surveys, distribution, abundance, and trend of belugas (delphinapterus leucas) in cook inlet, alaska, june 2018. seattle, wa: alaska fisheries science center, national oceanic and atmospheric administration, national marine fisheries service. sjare b.l. & smith t.g. 1986. the vocal repertoire of white whales, delphinapterus leucas, summering in cunningham inlet, northwest territories. canadian journal of zoology 64, 407–415, doi: 10.1139/z86-063. spackman e., senne d.a., myers t.j., bulaga l.l., garber l.p., perdue m.l., lohman k., daum l.t. & suarez d.l. 2002. development of a real-time reverse transcriptase pcr assay for type a influenza virus and the avian h5 and h7 hemagglutinin subtypes. journal of clinical microbiology 40, 3256–3260, doi: 10.1128/jcm.40.9.3256-3260.2002. st. aubin d.j., smith t.g. & geraci j.r. 1990. seasonal epidermal molt in beluga whales, delphinapterus leucas. canadian journal of zoology 68, 359–367, doi: 10.1139/z90-051. st. leger j.a. 2007. hydrocephalus and nonsuppurative meningoencephalitis associated with brucella sp. infection in two live-stranded dolphins. paper presented at the 38th annual conference of the international association for aquatic animal medicine, 5–9 may, orlando, fl. st. leger j., raverty s. & mena a. 2018. cetacea. in k.a. terioet al. (eds.): pathology of wildlife and zoo animals. pp. 533–568. philadelphia, pa: elsevier. stoskopf m.k., willens s. & mcbain j.f. 2001. pharmaceuticals and formularies. in f.m.d. gullandet al. (eds.): crc handbook of marine mammal medicine. 3rd edn. pp. 703–722. boca raton, fl: crc press. sweeney j.c., stone r., campbell m., mcbain j., st. leger j., xitco m., jensen e. & ridgway s. 2010. comparative survivability of tursiops neonates from three u.s. institutions for the decades 1990–1999 and 2000–2009. aquatic mammals 36, 248–261, doi: 10.1578/am.36.3.2010.248. teare a. 1991. medical record systems for the next century: the case for improved health care through integrated data base. journal of zoo and wildlife medicine 22, 389–391. tizard i. 1992. veterinary immunology. philadelphia, pa: w.b. saunders co. vangay p., ward t., gerber j.s. & knights d. 2015. antibiotics, pediatric dysbiosis, and disease. cell host & microbe 17, 553–564, doi: 10.1016/j.chom.2015.04.006. walsh m.t. & gearhart s. 2001. intensive care. in f.m.d. gullandet al. (eds.): crc handbook of marine mammal medicine. 3rd edn. pp. 689–702. boca raton, fl: crc press. wang d., zhang x., wang k., wei z., würsig b., braulik g.t. & ellis s. 2006. conservation of the baiji: no simple solution. conservation biology 20, 623–625, doi: 10.1111/j.1523-1739.2006.00471.x. winhall w. 2012. hand raising and conditioning of neonate beluga whale (delphinapterus leucas). soundings 37, 16–21. zagzebski k.a., gulland f.m., haulena m. & lander m.e. 2006. twenty-five years of rehabilitation of odontocetes stranded in central and northern california, 1977 to 2002. aquatic mammals 32, 334–345, doi: 10.1578/am.32.3.2006.334. zarogoulidis p., kioumis i., pitsiou g., porpodis k., lampaki s., papaiwannou a., katsikogiannis n., zaric b., branislav p., secen n., dryllis g., machairiotis n., rapti a. & zarogoulidis k. 2014. pneumothorax: from definition to diagnosis and treatment. journal of thoracic disease 6, suppl. 4, s372–s376, doi: 10.3978/j.issn.2072-1439.2014.09.24. an observation of white whale (delphinapterus leucas) mating behaviour in the wild research note an observation of white whale (delphinapterus leucas) mating behaviour in the wild christian lydersen,1 kerstin langenberger2 & kit m. kovacs1 1norwegian polar institute, tromsø, norway 2lohmar, germany abstract herein we describe mating behaviour observed in a group of 20 white whales in svalbard, norway. a single female was the centre of attention during the 45-minute encounter, which was observed, photographed and videotaped at an ice edge in storfjorden in june 2022. several males surrounded the female and vigorously herded her from all sides. the female spy-hopped regularly, and sometimes her whole body was pushed out of the water by the other animals. high tail-lifts and tail-slapping were frequently performed by males, and erect penises were observed many times. trumpet calls were also heard. at one point, three males with erect penises pressed themselves against the female simultaneously. the female was bleeding from wounds on her head and neck that were seemingly inflicted by bites from the other whales. she was also bleeding from her genital slit. a single copulation was seen at the surface, but it is likely that multiple males mated successfully with the female during the encounter. the event was more boisterous and violent than what has been described in captive white whales. we cannot assess how representative this observation is of typical reproductive behaviour for the species. but the encounter was remarkably similar to what has been described for several species of bottlenose dolphins that have male alliances that consort with individual females, restricting the female’s escape and keeping her accessible to mating only by members of the group. keywords aggressive group mating; beluga; forced copulation; svalbard norway; reproductive behaviour   citation: polar research 2023, 42, 8875, http://dx.doi.org/10.33265/polar.v42.8875 copyright: polar research 2023. © 2023 c. lydersen et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 7 march 2023 competing interests and funding: the authors report no conflict of interest. the publication charges for this article were paid by the norwegian polar institute. correspondence: lydersen, norwegian polar institute, fram centre, po box 6606 stakkevollan, no-9296 tromsø, norway. e-mail: christian.lydersen@npolar.no to access the supplementary material, please visit the article landing page   introduction white whales (delphinapterus leucas) have a circumpolar arctic and subarctic distribution (o’corry-crowe 2018). twenty-one stocks are currently recognized (hobbs et al. 2019); one of these resides around svalbard, norway. this is one of the smallest stocks, which was recently estimated to number 549 individuals (95% confidence interval: 436−723; vacquie-garcia et al. 2020), although white whales are the most commonly observed cetacean in svalbard (storrie et al. 2018; bengtsson et al. 2022). reasons for this seeming discrepancy include the fact that white whales are easy to spot and spend most of their time in the summers in coastal waters off the west coast of svalbard, where their distribution overlaps with people (vacquie-garcia et al. 2018). white whales in svalbard have been studied since the mid-1990s (see lydersen & kovacs 2021 for review), but very little is known about their reproductive biology locally. this is also true for white whales generally throughout their range in the wild. lomac-macnair et al. (2015) describe socio-sexual behaviour and probable mating behaviour for cook inlet, alaska, white whales. however, a variety of socio-sexual behaviours take place among cetaceans for social purposes, such as developing and maintaining relationships between individuals that are not actually mating. such behaviour can occur across and within age and sex groups. mating behaviour in most mammals, on the other hand, is related to conception and involves sexually mature individuals of the two sexes (hill et al. 2015). the cook inlet white whale interactions described by lomac-macnair et al. (2015) were observed from an aircraft on two different days, and in one case, they were photo-documented. the encounter that was photographed involved a group of nine animals. six of these whales formed three pairs, each of which displayed socio-sexual behaviours. these included ventrum-to-ventrum contact, ventral presentations, pelvic thrusting, nodding and rubbing. the second encounter involved four adult white whales engaged in socio-sexual behaviours. two of these white whales chased another individual and appeared to manoeuvre for proximity to this third central animal. the various socio-sexual behaviours observed in cook inlet resembled those previously described by hill et al. (2015) for captive white whales. these authors developed a catalogue of socio-sexual behaviours in white whales based on 800 hours of observations over a seven-year period, involving 11 animals of different ages, including both males and females. when this catalogue was applied to white whales at two other facilities, the behavioural similarities suggested that they were typical behaviours for the species. several other studies of sexual or socio-sexual behaviour among captive white whales have been reported in the literature (recchia 1994; glabicky et al. 2010; ham et al. 2022), but only lomac-macnair et al. (2015) have reported socio-sexual behaviour of white whales in the wild. observation in svalbard during a cruise in svalbard waters with the ship national geographic endurance (national geographic n.d.), a pod of white whales was observed in dense pack ice at a fast-ice edge in northern storfjorden (78°24.9n, 019°11.9e), on 4 june 2022. initially, it was a large group containing many small grey juveniles as well as adults. this large pod split and a group of 20 large animals (one of them grey and the rest white) commenced very boisterous behaviour. this group of whales clustered tightly and performed highly synchronized behaviours; most members of the group surfaced and dove simultaneously. it became clear after some time that the centre of attention was a single white female that was clearly distinguishable, in part because she was smaller than most of the other animals and was bleeding from wounds in several places, mainly on the head (fig. 1). fig. 1 the female white whale bleed from the head and neck, wounded (likely by biting) by surrounding males. all body parts of this female whale were observed at various times. she spy-hopped frequently, and sometimes her whole body was pressed out of the water by animals below her (fig. 2). high tail-lifts and tail-slapping were frequently performed by males in the group (fig. 3), and erect penises were observed many times (fig. 4). the males formed a tight cluster around the female and herded her toward the ice edge. the group remained within 15 m of the ice edge most of the time, sometimes diving beneath the ice. it appeared as though the males prevented the female from diving deeply or swimming away, herding her from all sides. the female’s bleeding wounds seemed to be inflicted by bites from the other whales. in addition to bleeding from the head, she also bled from other body parts including the vaginal slit (see supplementary video). at one point, three males with erect penises pressed themselves against the female simultaneously. at least one successful mating attempt was photographed at the surface. a male with an erect penis came alongside the female, who gradually rolled over such that she had her ventral side up, and intromission occurred (fig. 5). given the number of males involved in the group, the 45-minute duration of the event and the extremely dynamic movements by the males during the interactions, it is likely that there were multiple mating events that involved more than one male. fig. 2 the female white whale spy-hopped (top) and was pushed out of the water by other animals in the group. fig. 3 male white whales lifted their flukes and lower parts of their bodies into the air, often terminating in tail-slapping the surface of the water. fig. 4 a white whale attempts copulation, one of the many occasions in which an erect penis was observed. fig. 5 a successful copulation, wherein a male white whale with an erect penis came alongside the female, which rolled so that her ventral side was up, and intromission occurred. the white whales did not react to the ship, which approached to about 120 m. the behaviour of the group persisted, and the whales approached the ship to approximately 100 m. when they were close to the ship, observers heard several distinct, loud trumpeting sounds during exhalations from one or more individuals (supplementary video). a few minutes later, the group dissolved, and the whales swam away along the ice edge. the whole event within the group of 20 lasted approximately 45 minutes. discussion this is likely the first photo-documentation of mating in free-living white whales, at least in the scientific literature. in their account of an observation of white whale socio-sexual behaviour, lomac-macnair et al. (2015) could not determine the sex of the animals or confirm if mating occurred. their observations were of animals of similar size. because cook inlet white whales display the sexual size dimorphism typical of most white whale stocks, with males being larger than females (vos et al. 2020), it seems most likely that the socio-sexual behaviour lomac-macnair et al. (2015) described took place between animals of the same sex. given the lack of direct observations, the timing and location of mating is not known for white whales in the wild. on the basis of the gestation period and timing of calving in the eastern canadian arctic, brody (1989) suggested that white whales likely mate in spring in offshore areas or in polynyas. in a review based on traditional ecological knowledge in chukotka, russia, mymrin et al. (1999) said that mating takes place in the autumn, and that the male white whales whistle under water and the females respond to the whistles, coming to mate with the males. in captivity, copulatory behaviour (based on the observation of pelvic thrusting) was studied on a seasonal basis by glabicky et al. (2010). a pelvic thrust was defined as any instance in which one whale approached another, rolled ventrally toward the other animal, and made contact with the other whale in its genital region, regardless of whether an erection was seen or not. male-on-male pelvic thrusting varied across the months, while male-on-female pelvic thrusting peaked in march, suggesting that this was the period of the year when copulations occur. of the 910 thrusting events observed by glabicky et al. (2010) among adults, 59.7% were male-on-male, while 40.3% were confirmed to be male-on-female. during bisexual encounters, an erection was seen during 59.2% of the observations, whilst intromission was observed in less than 1% of them (glabicky et al. 2010). in the captive studies of white whale mating by glabicky et al. (2010) and hill et al. (2015), most groups were small, and only two individuals were involved in mating events normally, although there were sexual interactions for all combinations of sexes and various age groups. even in facilities housing several adults of each sex together, no documented captive mating interactions resemble the copulatory behaviour seen in svalbard. in light of the incident described herein, a report by degerbøl & nielsen (1930) of violent behaviour amongst white whales in greenlandic waters during spring may have described sexual behaviour: during the spring of 1918 three white whales were seen chasing each other, circling around within a small area. it appeared to be some kind of a fight, with the two largest animals ramming their heads into the abdomen of a smaller one, resulting in the lower part of that animal being lifted out of the water. the fight lasted for about a half hour, terminating when the smallest whale was suddenly dead, and the two others disappeared. the greenlanders that were watching got the dead animal on shore and i investigated it. it turned out to be an adult female. externally there was nothing extraordinary to see except blood oozing out from the genital slit, but internally there was a lot of bruising in the area around the genital slit. birth had not occurred. (degerbøl & nielsen 1930: 123–124; our translation from danish) further in the same publication, degerbøl & nielsen say that “it is not that rare that the greenlanders find dead females that have been exposed to the same treatment. it is very likely that the males in their erotic wildness harass the poor female so long that she dies” (1930: 124–125; our translation). this violent behaviour resembles what was observed in svalbard. in captive white whales, 80% of 13 observed conceptions occurred during the months of march to may, and the mean gestation of nine pregnancies was 475 ± 20 days (robeck et al. 2005). the event described in the present paper happened on 4 june; if this is in the general period for mating in svalbard white whales, the calving period should be in august or september. during research on white whales in svalbard, and in the same fjord (storfjorden), in early autumn, we have caught calves with attached umbilical cords that we estimated to be less than a week old (birkeland et al. 2005; lydersen & kovacs 2021). this is a good fit with a mating period in early june, though the calving period in svalbard and elsewhere is thought to be modestly long (kmk and cl, pers. obs.; brody 1989). other cetaceans are known to be either very boisterous or quite violent during mating episodes. boisterous mating is seen in species such as right whales (eubalaena spp.) and dusky dolphins (lagenorhynchus obscurus), which undertake scramble competition in a tight group for access to females; these species usually have large testicles, and sperm competition is assumed to determine mating success (e.g., kraus & hatch 2001; orbach et al. 2014). mating violence is common in cetacean species in which males compete directly with one another for access to females, such as sperm whales (physeter macrocephalus) and risso’s dolphin (grampus griseus). these species are generally very sexually dimorphic, and males are often heavily scarred (mcleod 1998; panagiotopoulou et al. 2016). white whales have normal-sized testicles, so sperm competition is not likely a major driving force for fitness of males. given the significant size dimorphism in white whales, it could be hypothesized that males compete for access to reproductive females. however, when mating systems involve direct competition between males, wounding is usually restricted to male-male fighting events, whilst it was only the female that was observed to have been bitten and bleeding in this encounter in svalbard. the cetacean mating behaviour that most closely resembles the observation documented here is seen in bottlenose dolphins (tursiops truncates and t. aduncas), which form male alliances that cooperate in consorting and mating with an individual female (wells et al. 1987; möller et al. 2001; mesnick & ralls 2018). consortships in these dolphins are typically initiated by aggressive herding behaviours such as biting, hitting, chasing and threat displays or outright ‘captures’, followed by intermittent aggression toward the female throughout the consortship (connor et al. 1992; connor & krützen 2015); female injuries are not uncommon (wallen et al. 2016). given that (1) white whales are thought to live in complex fission–fusion societies and male alliances have been described in white whales around svalbard (o’corry crowe et al. 2020) and (2) svalbard white whales have unexplained scars and injuries that have previously been thought to be from ice-wounding or polar bear (ursus maritimus) encounters (kmk and cl, pers. obs.), the observations reported herein might represent the norm for mating behaviour by this species in the wild. the trumpet-like whistles might be analogous to dolphin ‘pops’ in co-ordinating male behaviour (king et al. 2019), or they could be threats to males outside the group, an interpretation that is consistent with the males’ tail-slapping that was also observed. the more passive mating behaviour of white whales in human care might be a product of small group size and long-term familiarity. acknowledgements the authors thank ann kristin balto, picture archivist at the norwegian polar institute, for help with the figures. reviews by jared towers and livia gerber helped us improve the manuscript. references bengtsson o., lydersen c. & kovacs k.m. 2022. cetacean spatial trends over time (2005–2019) in svalbard, norway: climate change and svalbard’s whales. polar research 41, art. no. 7773, doi: 10.33265/polar.v41.7773. birkeland a., kovacs k.m., lydersen c. & grahl-nielsen o. 2005. transfer of fatty acids from mothers to their calves during lactation in white whales (delphinapterus leucas). marine ecology progress series 298, 287–294, doi: 10.3354/meps298287. brody p.f. 1989. the white whale delphinapterus leucas (palls, 1779). in s.h. ridgway & r. harrison (eds.): handbook of marine mammals. vol. 4. river dolphins and the larger toothed whales. pp. 119–144. london: academic press. connor r.c. & krützen m. 2015. male dolphin alliances in shark bay: changing perspectives in a 30-year study. animal behaviour 103, 223–235, doi: 10.1016/j.anbehav.2015.02.019. connor r.c., smolker r.a. & richards f. 1992. dolphin alliances and coalitions. in a.h. harcourt & f.b.m. de waal (eds.): coalitions and alliances in humans and other animals. pp. 415–443. new york: oxford university press. degerbøl m. & nielsen n.l. 1930. biological observations and measurements of the white whale (delphinapterus leucas (pall.)) and its fetus. meddelelser om grønland 77, 119–144. (in danish with english summary.) glabicky n., dubrava a. & noonan m. 2010. social–sexual behavior in captive beluga whales (delphinapterus leucas). polar biology 33, 1145–1147, doi: 10.1007/s00300-010-0790-3. ham j.r., lilley m.k., lelekach j., miller m.r., robeck t.r., pellis s.m. & hill h.m.m. 2022. the emergence and early development of socio-sexual behavior in beluga calves (delphinapterus leucas). behavioural processes 200, article no. 104695, doi: 10.1016/j.beproc.2022.104695. hill h.m., dietrich s., yeater d., mckinnon m., miller m., aibel s. & dove a. 2015. developing a catalog of socio-sexual behaviors of beluga whales (delphinapterus leucas) in the care of humans. animal behavior and cognition 2, 105–123, doi: 10.12966/abc.05.01.2015. hobbs r.c., reeves r.r., prewitt j.s., desportes g., breton-honeyman k., christensen t., citta j.j., ferguson s h., frost k.j., garde e., gavrilo m., ghazal m., glazov d.m., gosselin j.-f., hammill m., hansen r.g., harwood l., heide-jørgensen m.p., inglangasuk g., kovacs k.m., krasnova v.v., kuznetsova d.m., lee d.s., lesage v., litovka d.i., lorenzen e.d., lowry l.f., lydersen c., matthews c.j.d., meschersky i.g., mosnier a., o’corry-crowe g., postma l., quakenbush l.t., shpak o.v., skovrind m., suydam r.s. & watt c.a. 2019. global review of the conservation status of monodontid stocks. marine fisheries review 81(3–4), 1–53, doi: 10.7755/mfr.81.3–4.1. king s.l., allen s.j., krützen m. & connor r.c. 2019. vocal behaviour of allied male dolphins during cooperative mate guarding. animal cognition 22, 991–1000, doi: 10.1007/s10071-019-01290-1. kraus s.d. & hatch j.j. 2001. mating strategies in the north atlantic right whale (eubalaena glacialis). journal of cetacean research and management 2 (special issue), 237–244. lomac-macnair k.s., smultea m.a., cotter m.p., thissen c. & parker l. 2015. socio-sexual and probable mating behavior of cook inlet beluga whales, delphinapterus leucas, observed from an aircraft. marine fisheries review 77(2), 32–39, doi: 10.7755/mfr.77.2.2. lydersen c. & kovacs k.m. 2021. a review of the ecology and status of white whales (delphinapterus leucas) in svalbard, norway. polar research 40, article no. 5509, doi: 10.33265/polar.v40.5509. mcleod c.d. 1998. intraspecific scarring in odontocete cetaceans: an indicator of male “quality” in aggressive social interactions? journal of zoology 244, 71–77, doi: 10.1111/j.1469-7998.1998.tb00008.x. mesnick s. & ralls k. 2018. mating systems. in b. wursig et al. (eds.): encyclopedia of marine mammals. pp. 586–592. london: elsevier. möller l.m., beheregaray l.b., harcourt r.g. & krützen m. 2001. alliance membership and kinship in wild male bottlenose dolphins (tursiops abuncus) southeastern australia. proceedings of the royal society b 268, 1941–1947, doi: 10.1098/rspb.2001.756. mymrin n.i., the communities of novoe chaplino, sireniki, uelen, and yanrakinnot & huntington h.p. 1999. traditional knowledge of the ecology of beluga whales (delphinapterus leucas) in the northern bering sea, chukotka, russia. arctic 52, 62–70, doi: 10.14430/arctic910. national geographic n.d. national geographic endurance. accessed on the internet at https://www.nationalgeographic.com/expeditions/ships/national-geographic-endurance/ on 26 january 2023. o’corry-crowe c., suydam r., quakenbush l., smith t.g., lydersen c., kovacs k.m., orr j., harwood l., litovka d. & ferrer t. 2020. group structure and kinship in beluga whale societies. scientific reports 10, article no. 11462, doi: 10.1038/s41598-020-67314-w. o’corry-crowe g.m. 2018. beluga whale delpinapterus leucas. in b. würsig et al. (eds.): encyclopedia of marine mammals. pp. 93–96. london: elsevier. orbach d.n., packard j.m. & würsig b. 2014. mating group size in dusky dolphins (lagenorhynchus obscurus): costs and benefits of scramble competition. ethology 120, 804–815, doi: 10.1111/ryh.12253. panagiotopoulou o., spyridis p., abraha h.m., carrier d.r. & pataky t.c. 2016. architecture of the sperm whale forehead facilitates ramming combat. peerj 4, e1895, doi: 10.7717/peerj.1895. recchia c.a. 1994. social behaviour of captive belugas, delphinapterus leucas. whoi-94-03. phd dissertation, woods hole oceanographic institute/massachusetts institute of technology. robeck t.r., monfort s.l., calle p.p., dunn j.l., jensen e., boehm j.r., young s. & clark s.t. 2005. reproduction, growth and development in captive beluga (delphinapterus leucas). zoo biology 24, 29–48, doi: 10.1002/zoo.20037. storrie l., lydersen c., andersen m., wynn r.b. & kovacs k.m. 2018. determining the species assemblage and habitat use of cetaceans in the svalbard archipelago, based on recorded observations from 2002–2014. polar research 37, article no. 1463065, doi: 10.1080/17518369.2018.1463065. vacquie-garcia j., lydersen c., ims r.a. & kovacs k.m. 2018. habitats and movement patterns of white whales delphinapterus leucas in svalbard, norway in a changing climate. movement ecology 6, article no. 21, doi: 10.1186/s40462-018-0139-z. vacquié-garcia j., lydersen c., marques t.a., andersen m. & kovacs k.m. 2020. first abundance estimate for white whales (delphinapterus leucas) in svalbard, norway. endangered species research 41, 253–263, doi: 10.3354/esr01016. vos d.j., shelden k.e.w., friday n.a. & mahoney b.a. 2020. age and growth analyses for the endangered belugas in cook inlet, alaska. marine mammal science 36, 293–304, doi: 10.1111/mms.12630. wallen m.m., patterson e.m., krzyszczyk e. & mann j. 2016. the ecological costs to females in a system with allied sexual coercion. animal behaviour 115, 227–236, doi: 10.1016/j.anbehav.2016.02.018. wells r.s., scott m.d. & irvine a.b. 1987. the social structure of free-ranging bottlenose dolphins. current mammalogy 1, 247–305, doi: 10.1007/978-1-4757-9909-5_7. smedsrud.indd 267smedsrud 2003: polar research 22(2), 267–286 formation of turbid ice during autumn freeze-up in the kara sea lars h. smedsrud a one-dimensional (vertical) model is used to estimate the mass of icerafted sediment in turbid sea ice on the shallow kara sea shelf during autumn freeze-up. sediment is entrained into the ice through aggregation with frazil ice crystals that are diffused downwards by wind-generated turbulence. data from local meteorological stations are used to force the model, while water stratifi cation and sediment concentrations from the area are used to initiate the model. model results indicate a 0.2 m thick layer of slush ice created during 48 h with a mean wind of 6 m/s and an air temperature of –10 °c. this ice contains ca. 20 mg/l of sediment, or in total ca. 2 % of the annual sediment discharge by nearby rivers. in shallow areas (< 20 m depth) the process is very effective with winds of ca. 12 m/s, and the process can incorporate many years of sediment discharge. in the deeper areas (> 20 m depth), the strong salinity stratifi cation implies that winds above 18 m/s are needed for the process to be effective. for the rest of the winter months the same process may lead to additional sediment incorporated in a coastal polynya, but the freeze-up alone has the capacity to incorporate the total summer discharge of sediment into the surface ice. calculated sediment concentrations in the surface ice cover are in the range 3 mg/l 19 g/l, in good agreement with available fi eld data. l. h. smedsrud, geophysical institute, allègaten 70, university of bergen, no-5007 bergen, norway, larsh@gfi .uib.no. the arctic ocean is surrounded by shallow seas which are nearly ice-free in the summer and icecovered during the long winter. some time during september–october the upper mixed layer reaches its freezing point and the falling snow, or frozen sea spray, initiates the formation of the sea ice cover. if conditions are calm during the autumn freeze-up, the sea ice crystals will grow downwards to form a uniform sheet of congelation ice. in contrast, a turbulent freeze-up will form free-fl oating frazil ice crystals, which are likely to collide with, and aggregate to, sediment in suspension (smedsrud 2001). this results in turbid ice: granular sea ice with the ice-rafted sediment (irs) widely distributed throughout the ice (kempema et al. 1989). such ice has been sampled in the laptev, beaufort and kara seas (osterkamp 1984; nürnberg 1994; smedsrud & eicken 2003). this study considers the formation of turbid ice in the kara sea, which has a wide shelf— about 220 km, with large areas shallower than 60 m. sediment enters from the ob and yenisey rivers and is introduced from coastal and shoreface erosion. the ob and yenisey rivers discharge massive quantities of sediment which may carry bonded pollutants, including heavy metals, organochlorines and radionuclide contaminants. if this sediment is incorporated into sea ice and the sea ice becomes second-year ice, the sediment may be transported to the barents sea or fram strait. here sea ice melts rapidly, releasing the sediment and bonded pollutants. based on topography, six different areas of the 268 formation of turbid ice during autumn freeze-up in the kara sea kara shelf (here defi ned as the area with depths less than 100 m, 70 100° e; fig. 1) are selected, and typical vertical stratifi cations (salinity profi les) are then chosen, based on available ctd data. the river infl ow and sediment processes on the kara shelf which initialize the model runs are discussed. the atmospheric forcing—wind, snow and air temperature—is presented and this forms the forcing for the vertical frazil and sediment model: frasemo (smedsrud 2002). sensitivity tests towards different forcing, discussion of model limitations and comparison of results with available fi eld data comprise the last part of the paper. kara sea background in shallow shelf seas such as the kara sea there is a considerable interannual and seasonal variation in climatic forcing. in the kara sea, confi dence in observational data is further reduced by the sparseness of the observations, which are often of short duration. there is considerable variation in hydrography (pavlov & pfi rman 1995), especially in the shallow regions most important for the sediment entrainment processes. the ice cover of the kara sea has rarely been sampled. this is because most cruises to the area have taken place in august–september, when the sea is generally not covered by ice and is easily accessed. monthly mean sea ice concentration from smmr data is about 50 % for the kara shelf in october and 80 90 % in november. from december to may ice concentrations are 90 100 % all over the kara sea (gloersen et al. 1992). the mean seasonal hydrography and circulafig. 1. map of the kara sea and surrounding islands. the meteorological stations at dikson and golomyanny islands are indicated with asterisks. 269smedsrud 2003: polar research 22(2), 267–286 tion was modelled by harms & karcher (1999), showing satisfactory results for the hydrography and currents on the shelf. modelled surface currents are generally north-eastward, driven by the wind fi elds and steered by topography. the river water fl ows more or less directly along the siberian coast as a strong surface current (ca. 10 cm/s) which leaves through vilkitsky strait, between severnaya zemlya and the mainland. in summer, after the sea ice has melted, the wind forces some of the river water out into the central kara sea. below the surface current (25 50 m depth) is a counter current fl owing towards the estuaries in a southward direction all year. atlantic water enters the kara sea from the north, in the deep trough just east of franz josef land, with a core of 1.5 °c and 34.94 psu at 300 m depth. this water, considered a response to the northward fl owing surface water, fl ows southwards and rises until it comes within reach of surface driven mixing (hanzlick & aagaard 1980). this general picture is confi rmed by current observations (johnson et al. 1997). subtidal variability is high. many current meters frequently show averaged values of 20 cm/s for 12.5 h blocks. directions are mostly northwards in the surface layer. the subtidal variability north of the estuaries correlates well with the local wind, so the winds can play a strong role in spreading the river waters toward the north-west (johnson et al. 1997). the kara sea is dominated by semi-diurnal tidal oscillations. about 150 km north of the estuaries semi-diurnal currents exceed 50 cm/s (johnson et al. 1997). for the same rig the mean current speed was only 3 cm/s in the north-west direction (11 day long record). the high tidal amplitude may be partially explained by co-oscillating tides at the mouths of the estuaries. tidal currents are generally in the range 10 25 cm/s (kowalik & proshutinsky 1994). topography the bathymetry of the shallow kara sea shelf is not known in detail. the etopo 5 global data base has been used in fig. 2 and 5 data differ signifi cantly from specifi c depths at stations in nygaard (1995), but the average values over the wide shelf should be correct. the discussion of the shelf processes is limited to depths down to 60 m. this makes the total area of the shelf fig. 2. bathymetry of the kara shelf (etopo 5 data). 270 formation of turbid ice during autumn freeze-up in the kara sea between the ob estuary and severnaya zemlya ca. 216 850 km2. three areas represented by their average depth are delineated to limit the model results and discussions of sensitivity: 0 20 m, 20 40 m and 40 60 m. the area with an average of 10 m depth is 118 035 km2, the 30 m average depth area is 67 710 km2, and 50 m average depth is 31 110 km2. stratifi cation vertical density stratifi cation is controlled mostly by salinity, which in turn is mostly governed by the river infl ow. the coriolis effect makes much of the fresh water follow the coast eastwards from the estuaries as a coastal current, gradually mixing with saltier water along the way. prevailing winds from the north to north-east during the summer may lead to a spreading of the mixed layer and the river water northwards through ekman transport (fig. 3a). as winds vary, the spreading of river water may vary considerably from year to year. figure 3a shows the general picture from recent cruises: there is a region outside the ob and yenisey estuaries (around 90 km, or 50 nautical miles) with a surface salinity of less than 10 psu. the focus here is the autumn freeze-up in october, when the river discharge has virtually ceased, so the winter situation is also relevant (fig. 3b). these are the only available winter data, together with comparable maps from the same months in 1978 and 1980. in these two years the low salinity surface water was confi ned closer to the coast than in 1979. in winter, surface salinities have increased to above 20 psu outside the estuaries, whereas in the region to the east salinities are between 26 and 30 psu, close to values in summer. values at the sea fl oor are close to 33 psu in winter as well, so the vertical gradients are less than 10 psu outside the estuaries, and between 3 5 psu east of 400 fig. 3. observed surface salin i ties from the kara sea. (a) sal inities from september and october 1978. (b) salinities from march and april 1979. obser vations are from the arctic and antarctic research institute, st. petersburg. (figure available on the internet at http://psc.apl.washington.edu/ anwap/karatands5seasons. html. printed with permission of the applied physics laboratory, polar science center, university of washington.) (a) (b) 271smedsrud 2003: polar research 22(2), 267–286 nautical miles in fig. 3. however, there is no indication that the water column becomes vertically homogeneous in shallow water during the winter. this could happen due to the salt released by the sea ice growth, but is opposed by the continuous outfl ow of river water. calculated freezing rates are 4 6 m/year (harms & karcher 1999). two different areas have been selected for the model. the most stratifi ed area, outside the estuaries and with surface salinities between 12 and 18 psu in the autumn (fig. 3a), will hereafter be referred to as “area e”. the other area further to the east on the shelf, with surface salinities between 26 and 30 psu, is henceforth “area s”. the regions between these two have stratifi cations somewhere in between. examples of vertical temperature and salinity profi les in the two areas are shown in fig. 4. the stratifi cation in salinity in summer for area e falls within the two measured profi les from 1994 and 1995 (fig. 4). these stations, about 70 km apart, were obtained in september, indicate some of the year-to-year variability found in area e. in winter stratifi cation is less, as indicated in fig. 3b. all surface values are above 20 psu. the lowest salinities (maximum stratifi cation) are shown in fig. 4. the northernmost portion of area e has winter surface salinities of about 33 psu and therefore no stratifi cation, but this is depths greater than 100 m. area s has less stratifi cation, comparable to the station at 35 m depth shown in fig. 4. in summer the upper mixed layer is about 10 m close to the coast, increasing off the coast (nygaard 1995). from 10 m and downwards, the stratifi cation close to the coast is similar to that of area e, but the northern portions in deeper water have values which are 1 2 psu higher. the summer and winter surface salinities (5 m depth) in area s are similar (fig. 3). in fact, the winter waters are slightly fresher than in summer. this might be due to the ice cover, which to some extent prohibits wind induced mixing and spreading of the diluted river water. the fast ice edge cuts through area s, but its position varies from year to year, from about 50 to 180 km off the coast (dmitrenko et al. 1998). the maximum fast ice edge corresponds closely to the 20 m isobath in fig. 2. winter stratifi cation in area s is close to that of the summer. the maximum stratifi cation is the same, but there is no distinct upper layer, and the salinity increases steadily downwards. surface temperatures in area e are up to 6 °c in summer. below the well mixed surface layer, an intermediate warm layer can be found (dmitrenko et al. 1998). this layer forms due to fig. 4. vertical temperature and salinity from chosen profi les outside the ob and yenisey estuaries on the kara sea shelf. karex 94 data from nygaard (1995); epoca 1995 data from krosshavn et al. (1997); russian ice-breaker data from sherwood (2000). 272 formation of turbid ice during autumn freeze-up in the kara sea the overlying fresh river water and can persist until ice formation starts. the layer may minimize formation of fast ice in years when the river water stays close to the coast. such a layer was not evident in the profi les shown in fig. 4. temperatures in the lower layers during summer are generally 0.1 0.3 °c above the in situ freezing point (tf). for a salinity of 32.0 psu, tf is –1.75 °c. observed temperatures normally fall in the range –1.3 to –1.5 °c. in winter the temperature on the kara shelf is close to the freezing point at all depths. the station from 1968 shown in fig. 4 indicates that the upper layer is cooled to the freezing point already in october. based on topography and stratifi cation, six different typical classes of stratifi cation have been chosen for model initialization (table 1). each class has an upper and lower mixed layer, representing averages over their depths. upper layer salinities are generally higher than the summer surface values in area e but are much lower than in winter (fig. 3). this is an attempt to represent the stratifi cation in late october, also adjusting for the sections from the 1990s. upper layer salinities in area s are slightly lower than given in fig. 3a because more river water was observed in this area in the 1990s. between the layers salinity is taken to vary linearly. as a simplifi cation, the temperatures of the water columns are set to the in situ freezing point. river infl ow and sediment the maximum river outfl ow to the kara sea occurs in june, with ca. 0.14 sv (106 m3/s) (pavlov & pfi rman 1995). this is about twice as much as in july and august and four times as much as in may, september and october. the rest of the year has a close to constant outfl ow of 0.01 sv. runoff anomalies persist for several years but the average value used in harms & karcher (1999)— 0.03 sv—is identical with the average of the years 1936–1964 (hanzlick & aagaard 1980). the range given is 0.023 to 0.04 sv. the kara sea rivers (ob, pur, taz, yenisey and pjasina), and the lena which empties into the laptev sea, have quite low sediment loads compared to other major rivers. together they drain close to 10 % of the total world land area draining into oceans but contribute less than 1 % of the total sediment discharge. this is because they drain low-lying (low relief) terrain, portions of which have been stripped of sediment by glaciers (milliman & meade 1983). the ob and yenisey rivers have average sediment loads of 41.5 mg/l and 23.2 mg/l, respectively, which makes a total of 29 × 106 tonnes per year. this is close to one third of the total calculated sediment discharge to the arctic ocean from the eurasian arctic (milliman & meade 1983). the average level of suspended particulate matter (spm) in the offshore area was found to be as low as 1.3 mg/l in august and september 1994 (evenset et al. 1999). for eight stations on the shelf in august and september 1995, with a mean depth of 31.5 m, values are 1.04 mg/l in the surface and 6.08 mg/l in the bottom layer (epoca 95, j. carroll, pers. comm.). the measurements were taken during calm atmospheric conditions. average spm in the estuaries during august and september are much higher than on the shelves: 3.7 mg/l in the yenisey and 18.8 mg/l in the ob (evenset et al. 1999). this confi rms that despite its smaller discharge the ob supplies more sediment than the yenisey. values are lower than the annual average and indicate that the major sediment volume probably discharges during the fl ood in june. the major sediment loads enter the kara sea when there is no ice growth. this means that even if some of these sediments are fl ushed onto the river ice or sea ice, this ice will melt not far from the river estuary. undoubtly, most of the sediment load will end up somewhere on the sea fl oor of the shelf, be resuspended during high turbulence events, and settle in quiet areas when conditions allow. the low levels of spm make it diffi cult to do grain size analyses on the sediment, so the size distribution of the bottom samples is important information. more than 50 % of the bottom sediment is generally silts or clay (2 rs < 63 µm), but variations are high. some stations have values as table 1. typical and simplifi ed water columns on the kara shelf. e 10 m e 30m e 50 m s 10 m s 30 m s 50 m upper layer m 0 4 0 8 0 15 0 4 0 10 0 20 salinity (psu) 12.0 17.7 20.0 20.0 25.0 28.0 lower layer m 6 10 14 30 20 50 6 10 20 30 30 50 salinity (psu) 20 31.6 33.0 25.0 33.0 33.0 273smedsrud 2003: polar research 22(2), 267–286 high as 97 % and a few shallow stations (12 17 m) have values around 5 %. grain size distribution varies little down core. figure 5 shows a surface sample where 79 % of the particles are smaller than 63 µm and the median diameter is close to 25 µm. modern sediment accumulation rates in the estuaries and on the kara shelf are ca. 0.1 cm/yr (evenset et al. 1999). this is much lower than the fl ux from the rivers. the rest of the sediment must be transported out of the area either as spm or irs. the initial sediment concentrations used are means from the shelf stations during epoca 95 (krosshavn et al. 1997). in area e the means of three stations were 2.0 mg/l in the upper layer and 8.9 mg/l in the lower. in area s values are lower: 0.7 mg/l in the upper layer and 4.4 mg/l in the lower (5 stations). depths were 20 54 m. atmospheric forcing air temperatures (ta ) and winds are of great importance when ice formation starts in the kara sea. together they allow us to estimate the heat fl ux from the water to the air, which is directly proportional to the volume of ice produced in a given area. the wind also controls the advection of ice. with southerly winds the newly grown ice will be advected northwards, leaving a polynya between the moving sea ice pack and the coast (or the fast ice edge). when the mixed surface layer is cooled slightly below the freezing point, frazil ice will start to form at the surface. the subsequent evolution of crystal growth, supercooling and turbulent diffusion of ice crystals in the model is described in the section which presents the model results, based on the atmospheric forcing. precipitation is also an important parameter. monthly mean climatological data show a considerable range in air temperature over the kara sea, from + 5 °c in the south-western parts in august to –33 °c over eastern parts in january. wind fi elds show strong monsoon-like variabilities due to the seasonal air pressure distribution over the arctic. from october to march strong stable winds prevail (maximum 8.5 m/s in february), with the wind mainly coming from the south and south-west (harms & karcher 1999). mean speeds in summer are lower (2 4 m/s) and more variable in direction, but northerly to north-easterly winds dominate. in the absence of very strong and steady currents on continental shelves, the sediment dispersal is mainly controlled by tidal currents or seasonal fl uctuations in wave and current intensity. maximum sediment transport typically accompanies storm activity (reading 1996). even if the tidal currents are relatively strong in the kara sea (10 25 cm/s, with up to about 50 cm/s near the ob estuary), tidal currents need to be much stronger to dominate sedimentation processes (reading 1996). wind forcing is therefore important, together with a good estimate of the frequency of storms, from the longest data records available. storm processes are also known to enhance or overprint sediment transport associated with most of the fair-weather processes (reading 1996). a data base from the period 1951–1992, including seven meteorological stations around the kara sea, is used to estimate the range in conditions during the autumn freeze-up. the data base utilizes records kept at the arctic and antarctic research institute in st. petersburg and what has previously been published in the russian literature (alexandrov et al. 2000). the meteorological stations at dikson and golomyanny islands (figs. 1, 2) are the ones closest to the kara shelf. table 2 contains parameters relevant to the freeze-up study, and includes the mean monthly air temperature (ta ), the maximum and minimum temperature of the record, mean precipitation during one month, wind speed means, maximum observed instantaneous wind speed during the given month, and average number of days per month with wind stronger than 15 m/s (gale days). the minimum temperature at golomyanny is fig. 5. size distribution of surface sediment outside the kara sea estuaries at 30 m depth (73° 23' n, 73° e). median size is 25 µm. (figure used with permission of j. carroll, unpubl. data; see also carroll & harms 1999; carroll et al. 1999.) 274 formation of turbid ice during autumn freeze-up in the kara sea below zero at least one day per month throughout the year (alexandrov et al. 2000). at dikson the average fi rst day of frost is 2 september, ranging from 12 august to 4 october. based on data from the years 1936–1965, there is a statistical probability of 95 % that the maximum wind speed at dikson is 39 m/s during one year, 46 m/s during fi ve years, 49 m/s during 10 years and 52 m/s during 20 years (alexandrov et al. 2000). the data base described above is compared to observations of wind and air temperature from dikson in the period 1936–1990 from the allrussian research institute of hydro meteorological information—world data centre. data are 6 hourly in the years 1936–1965 and 3 hourly in the years 1966–1990. these data confi rm that storms (wind speed > 25 m/s) occur 2 4 times a year. hurricanes (wind speed > 33 m/s) were common early in the record, but in the 1970s and 1980s wind speed decreased signifi cantly. of the total number of measurements (116 841), gale or stronger winds are observed 6.23 % of the time, storm or above 0.34 %, and hurricanes are observed 0.09 % of the time. the high wind situations (> 20 m/s) are associated with air temperatures between zero and –35 °c. the general picture that emerges is that the relatively ice-free kara sea shelf is cooled by a negative radiation balance and cold air temperatures from september. during october ta is about –10 °c and nearly all precipitation is snow. in november, ta is ca. –20 °c and average wind speeds are close to 7 m/s. storm episodes, which take place about 1.6 days every year on average, are likely to take place during the fall and winter. for the model forcing, the full range—from the mean (a moderate breeze) to a hurricane— is used (6, 12, 18, 24 and 30 m/s). the wind is directed along the coast in all runs. the highest wind episodes are of relatively short duration, so the storm (24 m/s) is applied over 24 h and the hurricane (30 m/s) over 12 h. in these cases, the model is started with 6 m/s during 6 h, then it is increased linearly to the given speed at 12 h. the wind speed is reduced over 6 h in the same way at the end. the air temperature is set at a constant –10 °c. this is the mean between dikson and golomyanny meteorological stations in october. the snowfall is set at a constant 1 mm/day, which is close to the measured mean value of 26 mm/month shown in table 2. the snow is divided equally over the fi ve size classes for frazil ice. the model sensitivity towards ta and snow is given in the section discussing sensitivity. the model frasemo is a vertical model that describes the state of a water column with time, as a result of surface forcing (wind, snow and ta ). horizontal current (along and onshore), salinity, temperature, (vertical) eddy viscosity and density are calculated in each vertical grid-cell. at the bottom, wave–current interaction resuspends sediment, and at the surface frazil ice crystals may form when the water is supercooled by a colder atmosphere. the different processes are illustrated in fig. 6. water density is calculated, including sediment and frazil ice concentrations. a more detailed description of the model is given by sherwood (2000), where the model was table 2. monthly mean atmospheric forcing on the kara shelf, august–december. dikson island golomyanny island parameter aug. sep. oct. nov. dec. aug. sep. oct. nov. dec. ta (°c) 5.0 1.6 –7.3 –17.6 –22.3 0.0 –3.3 –12.0 –20.7 –24.2 max ta (°c) 27 17 6 2 0 11 5 1 –1 0 min ta (°c) –12 –30 –43 –47 –49 –21 –36 –40 –46 –51 rain (mm) 43 23 2 19 7 wet snow (mm) 3 16 8 1 6 10 3 1 1 snow (mm) 6 24 19 20 3 6 15 11 11 wind speed(m/s) 6.3 6.9 7.4 6.9 8.3 5.3 6.4 6.4 6.0 6.5 max. speed (m/s) 34 28 > 40 40 > 40 30 29 31 gale days (days) 4 5 8 8 10 2 4 5 4 5 275smedsrud 2003: polar research 22(2), 267–286 developed and compared to analytic solutions for a variety of fl ows. the model runs presented here uses the mellor–yamada 2 1/2 turbulent closure model (mellor & yamada 1982). frasemo was developed further in smeds rud (2002) to include size spectra for frazil crystals and sediment, secondary nucleation of frazil crystals and aggregation between sediment and frazil. the model was thus “upgraded” from the one-size assumption of frazil ice in oms tedt (1985) to a size spectrum approach (svens son & oms tedt 1998), and verifi ed against large tank laboratory experiments with 24 h duration (smedsrud 2001). the frazil dynamics were shown to be adequately represented and the effi ciency of the aggregation process was empirically estimated through an aggregation factor α. the range of the fi ve size classes for the frazil crystal diameter is 25 µm 1.5 cm, and 1.15 µm 625 µm for the sediment grain diameter (smedsrud 2002). the spm is assumed to be in the smallest size group (diameter < 2 µm, clay). the sediment grain size distribution at the bottom is set as a fi ve class approximation of the measured sizes shown in fig. 5. this yields 5.4 % clay, 36.0 % fi ne and medium silt, 37.5 % coarse silt, 20.9 % fi ne sand and only 0.2 % medium and coarse sand. a time step of 2.0 s and a vertical grid spacing of 0.2 m is used in the calculations. due to the high velocities associated with the storms and hurricanes, the vertical grid spacing in these runs had to be increased to 0.4 m to prevent the bottom roughness from being bigger than the grid spacing in the wave–current boundary layer. the following values were discussed in smedsrud (2002). (i) a size-dependent growth of frazil ice is modelled using a constant nusselt number, nu = 1.5. (ii) secondary nucleation uses a maximum number concentration of crystals at each level (ni ), equal to 1.0 × 103. (iii) the aggregation factor α equals 0.005, the mean value. (iv) sizedependent rise and sinking velocities are constant for each size. an upper limit for the sediment concentration aggregated to frazil ice crystals has not been found. as irs concentrations in the laboratory experiments used to estimate α were quite low—ca. 100 mg/l (smedsrud 2001)—such an upper limit was not discussed when developing frasemo. frazil ice crystals are modelled to start melting when the temperature is above the freezing point. the melting rate is given by the turbulent heat conduction where melting is taking place all over the crystal surface, not just the edge of the frazil disk. the other standard parameters specifi ed are the same as in sherwood (2000) for turbulence, heat fl ux and sediment resuspension. the size dependent critical shear stress is calculated based on gelfenbaum & smith (1986), falling in the range 0.003 0.34 n/m2. tidal currents are observed to be quite strong (ca. 50 cm/s), but are not incorporated into the model. this is somewhat compensated for by fig. 6. schematic illustration of processes in the frazil and sediment model, frasemo. the vertical model is initialized with temperature and salinity profi les, and is forced by winds, snow and air temperature. (figure from sherwood 2000; reproduced with permission of the american geophysical union and the author.) 276 formation of turbid ice during autumn freeze-up in the kara sea using in situ sediment concentrations from the shelf, refl ecting the steady situation in the case of calm atmospheric conditions. a vertical model has obvious limitations in calculating the mixing of an upper and lower layer in that it cannot account for horizontal advection. this mixing is also found to be quite sensitive to the initial salinity profi le, the depth and the wind forcing. the depth and the stratifi cation have opposite effects: the shallow water is usually more stratifi ed than the deeper water. model results results are fi rst presented with respect to the 30 m depth and 18 m/s winds “base case”. other cases with varying wind forcing over the same depth are presented subsequently, followed by the other depths (10 and 50 m) and the profi les from the shelf. results are given as mass concentrations of ice and sediment per litre of water for all parameters. this implies that the porosity of frazil ice and sediment are not accounted for and that bulk densities of the hybrid aggregates would be signifi cantly smaller if the densities could be measured including the pore water. this is consistent with rise and sinking velocity calculations that use pure ice and sediment densities as given in tables 1 and 2 in smedsrud (2002). base case, 30 m depth outside the estuary (area e) the model is started from rest and the gale (18 m/s) is set constant for the 48 h model run. the initial stratifi cation is “e 30 m” presented in table 1. the gale produces an upward heat fl ux of 220 w/m2. this makes ice start freezing after 2 h, when the surface has cooled slightly below the fig. 7. model results for the base case: (a) temperature; (b) salinity; and (c) density anomaly. (a) (b) (c) 277smedsrud 2003: polar research 22(2), 267–286 freezing point (tf) of –0.96 °c. due to the presence of ice crystals from the snow, ice growth starts at once. supercooling remains low, only ca. 0.001 °c. the upward heat fl ux both cools and freezes the water, and after 48 h about 80 kg/m2 of ice is produced. the evolution of temperature is plotted in fig. 7a. the upper layer salinity increases from 17.7 to 20.5 psu over the 48 h (fig. 7b), due to both ice formation and mixing with the water in the 7 m thick halocline. the 18 m/s wind blowing along the coast creates an ekman transport with a speed of ca. 40 cm/s towards the coast (to the right in fig. 6) in the upper layer, and an outwards compensating current in the lower layer, which balances the on/off shelf transport. within 6 h the velocities are almost in a steady state and the offshore velocity in the lower layer is about 35 cm/s. at 6 h the alongshore velocities are close to 1 m/s at the surface, decreasing to 20 cm/s at the bottom, increasing slowly with time. the gale produces waves with a wave height of 3.4 m and a period of 7.0 s. the waves and the bottom stress from the current combine to resuspend sediment from the bottom. consequently spm increases steadily in the lower layer, making the lower layer denser (fig. 7c). frazil ice remains in the upper layer throughout the 48 h (fig. 8a). as the proportion of large crystals increases with time, more and more frazil gathers at the surface. surface concentrations increase from 10 g/l at 10 h to 115 g/l at 30 h, and 234 g/l at the end. at the end of 48 h, the total spm is 240 kg/m2, but nearly all of it is in the lower layer with concentrations of about 20 g/l (fig. 8b). in the upper layer, the initial 2 mg/l is decreased to less than 1 mg/l by the transformation to irs through aggregation with frazil ice. fig. 8. model results for the base case: (a) frazil ice concentration; (b) suspended particulate matter (spm); and (c) ice-rafted sediments (irs). (a) (b) (c) 278 formation of turbid ice during autumn freeze-up in the kara sea the irs concentration in the surface increases steadily with time (fig. 8c). surface irs reaches 35 mg/l in 24 h and 137.8 mg/l in 48 h, with 5.8 mg/l at 0.5 m depth. the irs, like the spm, consists of pure clay. in the lower layer where the spm concentration reaches 20 g/l, 66.8 % consists of clay, 31.6 % of fi ne and medium silt and 1.6 % of coarse silt. figure 9 shows the frazil ice concentrations plotted against depth at 48 h for the different size classes. the concentration of the smallest crystals is homogeneous down to 14 m depth and the larger crystals are more confi ned to the surface. the mass of frazil at 10 m depth increases from 0.5 g/l at 5 h to 2.0 g/l at the end. as seen in fig. 9, this is in the range of the small to medium classes, with corresponding low rise velocities (smedsrud 2002). the surface layer is about 0.2 m thick; the concentration at 0.3 m is 22.6 g/l and at 0.5 m 10.2 g/l. surface size distribution is 0.0, 1.1, 33.8, 43.2 and 21.9 % for the fi ve classes, from the smallest to the largest. after 10 h, more than 99 % of the frazil ice is aggregated to sediment. the density of this ice is given by eq. (17) in smedsrud (2002). due to the relatively low irs concentration, this density is increased by less than 1 kg/m3 from the pure ice density of 920 kg/m3. the frazil ice rise velocity is therefore decreased less than 1 mm/s for the largest crystals (and less for the smaller ones). area e: 30 m depth the moderate breeze (6 m/s) produces an spm concentration in the lower layer at 48 h of 1 g/l, compared to 20 g/l in the base case. in the upper layer spm stays close to the initial value of 2 mg/l, producing an irs of 17.8 mg/l at 48 h. the frazil ice stays in the upper 5 m, reaching 100 g/l at the end of the run. with the strong breeze (12 m/s), the lower layer spm increases to around 6 g/l at 48 h and the surface irs reaches 63.6 mg/l. the surface ice concentration ends up at 194.3 g/l and there is about 1 g/l at 10 m depth. the storm (24 m/s) lasts for 24 h, as indicated in fig. 10, is imposed linearly over 6 h from a moderate breeze over the fi rst 6 h and ceases in the same way at the end. the stratifi cation is weakened, but the layers persist. the lower layer spm is ca. 27 g/l at the end and in the upper layer ca. 500 mg/l. this produces a surface ice layer with 124 g/l of ice, an irs of 11.6 g/l and a density of 975 kg/m3. there is a homogeneous ice concentration of 2 g/l down to 12 m depth, with less than 1 mg/l of sediment. a very small portion of the crystals makes it down into the lower layer. these crystals aggregate to sediment so effi ciently that their buoyancy is lost, their density increases above that of the water and they sink to the bottom. at 48 h there is 1 g/l of this ice, with fig. 9. frazil ice concentration in the upper layer at 48 h (base case). the size classes are shown. 279smedsrud 2003: polar research 22(2), 267–286 a density 1422 kg/m3. the hurricane (30 m/s) lasts from 12 24 h, and ceases in the same way as the storm to the 6 m/s mean wind speed (fig. 10). at 48 h the upper layer salinity has increased to 24.8 psu. the lower layer has decreased to 27.7 psu. sediment is resuspended during the 12 h and does not deposit with the 6 m/s wind. the spm in the lower layer is about 20 g/l from 24 to 48 h. in the upper layer spm increases from ca. 300 mg/l at 24 h to 1 g/l at 48 h. due to the very strong turbulence, the ice is diffused effi ciently downwards at 24 h, ice concentrations decreasing gradually with depth from 4.3 g/l at the surface to 0.5 g/l at 15 m depth. the ice is buoyant down to 25 m depth at this stage and the surface irs is 160 mg/l. at 48 h the ice in the upper layer is well mixed, with around 4 g/l down to 10 m depth. the surface irs has reached 691.6 mg/l and the irs concentration is around 400 mg/l in the upper 10 m. the ice has negative buoyancy below and irs concentrations reach 2 g/l. an entrainment factor, xe = ( irs/spm ), is plotted for the fi ve different wind speeds over the area e 30 m water column (fig. 10). the initial spm value of the upper layer of 2 mg/l is used. figure 10 shows that it takes between 10 and 20 h for the surface ice to reach the initial spm concentration of 2 mg/l. as the hurricane changes to a moderate breeze over the course of 24 to 30 h, there is only a very slight increase in the irs after 30 h in this case. area e: 10 m depth with a moderate breeze, sediment and frazil ice stay close to the bottom and surface, respectively. spm in the lower layer is ca. 6 g/l at 48 h and the irs reaches 21.7 mg/l. surface ice concentration reaches 118 g/l. with the strong breeze (12 m/s), the two layers also stay intact. the spm concentration in the lower layer at 48 h is about 70 g/l—this is over three times as much as in the base case. this leads again to high surface spm (ca. 400 mg/l) and irs (10.5 g/l). there is about 4 g/l of frazil ice down to 5 m depth. at the bottom there is a small volume of sinking ice (1.6 g/l), loaded with 4 g/l of sediment. the gale mixes the two layers in 16 h. just before the mixing the spm in the upper layer is ca. 700 mg/l and the surface irs is 19.1 g/l. no sinking ice is formed, but this changes quickly. just after the mixing the density of the hybrid aggregates increases to above 1200 kg/m3. the rise velocity of the largest frazil crystals has changed from 28 mm/s in the pure state to a sinking velocity of 8 mm/s because of the aggregated sediment. at 48 h the sediment distribution is homogeneous, spm is ca. 32 g/l and irs is ca. 58 g/l, but there is more ice at the bottom (ca. 20 g/l) than at the surface. density of the sinking fig. 10. entrainment factor: surface irs concentrations divided by initial spm, for the e 30 m depth cases with different wind forcing, as indicated. 280 formation of turbid ice during autumn freeze-up in the kara sea ice is close to 2000 kg/m3. the storm is imposed gradually from 6 to 12 h and at 17 h mixing occurs. before this there is a thick layer of ice in the surface, increasing from 2 g/l at 5 m depth to 10 g/l at the surface. the surface ice has an irs of 440 mg/l and a density of 945 kg/m3. soon after this the ice starts to sink. the hurricane mixes the two layers fully at 15 h; before this the surface layer of ice (5 g/l) has an irs of 185 mg/l. the ice starts to sink shortly after homogeneous concentrations are reached. the ice concentration is “turned around” from the normal state, with no surface ice and about 14 g/l at the bottom, loaded with 57 g/l of sediment. area e: 50 m depth at this depth the moderate breeze resuspends little sediment and the only spm in the upper layer is the initial value of 2 mg/l. as frazil ice is confi ned to the upper layer, the irs reaches only 2.9 mg/l, with an ice concentration of 31.6 g/l. the strong breeze is able to diffuse some frazil ice (ca. 1 g/l) down to 10 m depth, but the spm is as low as with the moderate breeze. this increases the surface irs at 48 h to 17.0 mg/l. the average upward heat fl ux is increased from 73 to 144 w/m2 with the stronger wind. the surface ice concentration becomes 65 g/l at the end of the run. the gale resuspends sediment, but only to 15 m above the bottom. the heat fl ux is given by the forcing: 220 w/m2, which is equal to the base case. frazil ice is diffused further down into the surface layer, about 2 g/l at 15 m depth at the end. the surface irs becomes 37.1 mg/l in 87.8 g/l of ice. the storm resuspends sediment in the lower layer and diffuses frazil ice down to the halocline at 20 m depth. at the end of the turn the surface has 106.6 g/l of ice, with an irs concentration of 53.0 mg/l. the hurricane manages to resuspend enough sediment so that the upper layer spm is increased to 3 mg/l. frazil ice is diffused down to the halocline with 1 g/l from 4 15 m depth. at 2 m depth there is 3 g/l of frazil ice, and in the surface 78.5 g/l, with an irs concentration of 24.6 mg/l. this seems to be less than in the case with the storm, but the irs is just vertically more distributed (table 3). integrated over the surface ice layer, this is the largest irs concentration for the 50 m depth cases, as expected. shelf profi les the three stratifi cations chosen as typical for the shelf area between the ob and yenisey estuaries and severnaya zemlya are given in table 2. as the forcing is the same as for area e, this also forms a sensitivity study for the stratifi cation, and to some degree also for the initial spm concentration, which both are lower in this area. changes from the e cases are described below. in the 10 m case with moderate breeze the upper layer spm remains lower than in area e, resulting in a lower surface irs concentration: 6.9 mg/l. with the strong breeze, the sediment from the lower layer diffuses more easily than in area e and the upper layer spm increases to about 500 mg/l, increasing the irs at the end to 15.0 g/l. the gale needs 1 h less to mix the two layers compared to the area e case and the sinking ice density is further increased to 2200 kg/m3. the storm and the hurricane mix the less stratifi ed layers more easily and the ice becomes even more loaded with sediment. table 3. calculated irs concentrations (g/m2) after 48 hours in turbid sea ice for different water columns and wind speeds on the kara shelf. area is given in percent of the total area of 216 850 km2 for each column. cases where all the ice becomes negatively bouyant and tends to sink are indicated with –. total is given in tonnes. e 10 m e 30m e 50 m s 10 m s 30 m s 50 m total area 21.5 15.2 5.5 32.9 16.0 8.9 100 6 m/s 4.3 3.6 0.6 1.4 1.1 0.3 0.5 × 106 12 m/s 2104.6 12.7 3.4 3006.6 4.7 1.5 313.3 × 106 18 m/s – 33.2 7.4 – 19.1 3.2 1.9 × 106 24 m/s – 4715.8 10.6 – 9460.7 4.6 483.9 × 106 30 m/s – 4435.9 12.4 – 7487.2 79.0 407.7 × 106 281smedsrud 2003: polar research 22(2), 267–286 for 30 m depth, the moderate and strong breezes lead to smaller surface concentrations of irs than in area e because of the lower initial spm. with the gale, the weaker stratifi cation leads to an increase in the spm in the upper layer at about 46 h. because this happens so late in the integration, the surface irs concentration becomes lower than in the base case, again because of the lower initial spm. the storm resuspends more sediment with the weaker stratifi cation, resulting in an upper layer with a close to homogeneous concentration of 5 g/l of frazil ice with an irs of ca. 500 mg/l and a density of ca. 980 kg/m3. the hurricane is close to mixing the upper layer with the lower, but at 48 h there is still a halocline of 1 psu. the fl ux of spm into the upper layer is effi cient. the spm ends at 2.4 g/l. the ice in the surface layer is very close to neutrally buoyant, ca. 1025 kg/m3, but below 10 m depth the ice sinks. the surface ice layer is 10 m thick, has ca. 5 g/l of ice and about 800 mg/l of sediment. in the 50 m cases, the moderate and strong breezes and the gale give low irs concentrations due to the low initial spm. the storm is able to increase the upper layer spm slightly and during the hurricane the spm fl ux to the upper layer is larger than in area e because of the weaker stratifi cation. overview model results for vertically integrated irs concentrations at 48 h are given in table 3. only irs that is aggregated to ice and has a density lower than the upper layer is included in the integration. the stratifi cations used (area e 10 m to area s 50 m) are given in table 2. for each wind speed the irs concentration for each water column is multiplied with the respective area to form the total values. the unit, g/m2, is equivalent to tonnes/ km2. the lowest wind speed, the moderate breeze, is also the mean wind speed in the area. this wind produces the smallest irs mass as expected. the irs mass is increased by three orders of magnitude with a freeze-up during a strong breeze. table 3 shows the surprising result that the total mass of irs does not increase monotonically with wind speed. the formation of frazil ice with negative buoyancy due to the aggregated sediment makes the irs mass for the gale case lower than that for the strong breeze. as the ice in half the area (area e 10 m + area s 10 m) sinks, this effect becomes very important. the storm produces the largest mass of irs, the hurricane slightly less. this is because the increased irs concentration in area e 50 m and area s 50 m, due to the stronger wind, is lost in sinking irs in the area e 30 m and area s 30 m areas. at low wind speeds a higher irs mass is reached with the higher initial spm concentrations in the upper layer of area e. at higher wind speeds area s produces more irs because of the weaker stratifi cation. the transition takes place with a moderate breeze for 10 m, a storm for 30 m and a hurricane for 50 m depth. discussion the transition from free-fl oating frazil ice crystals to slush ice is a gradual process. the upper layer of crystals gradually becomes more compact. at some stage congealing starts between crystals, forming turbid sea ice: granular ice with irs. the transition is not well defi ned. sherwood (2000) stated that all model assumptions valid for water are also valid for the ice–water mixture until the surgace ice concentration has reached 10 g/l, or 1 %. in their experiments with wave damping by grease ice, martin & kauffman (1981) suggest that the transition from the free-fl oating frazil ice stage to the wave damping stage occurs at a concentration of 200 g/l. the transfer of momentum between the air and water is the source for turbulence in the calculations. the transfer of turbulent kinetic energy from the surface and down into the water is dependent upon the surface roughness length (z0), which should change when the surface ice layer changes. alam & curry (1998) suggests that z0 changes signifi cantly when the ice concentration reaches 400 g/l, when the grease ice starts to behave like a solid. the transition for the surface heat fl ux is parameterized in the same way as for momentum and again an ice concentration of 400 g/l is given as the critical value (alam & curry 1998). the thickness of the frazil ice layer can be estimated using the parameterization of alam & curry (1998). the frazil ice layer thickness is not defi ned explicitly because the horizontal approximation does not allow for a frazil ice depth profi le. using as a defi nition for the bottom of the frazil layer in frasemo the depth at which 90 % of the ice mass is reached in a vertical integral, 282 formation of turbid ice during autumn freeze-up in the kara sea starting at the surface and working downwards, gives a frazil layer thickness of 0.5 m (fig. 9). this is comparable to the frazil pile-up depth in alam & curry (1998), using a fetch of 1000 m and the 18 m/s gale of the base case. the slush ice will keep the thickness until it is transformed into solid ice. the surface layer of frazil is about the same thickness as the vertical grid spacing (20 40 cm), supporting the idea that the model results describe the physical processes until the frazil ice concentration is on the order of 200 g/l. the upper cell is representative of the surface ice layer and fl ux parameterizations at the surface are valid until an ice concentration of 400 g/l is reached. as the maximum ice concentration described here is 234 g/l (base case), this implies that the 48 h model runs presented here can all be regarded as “open water”. thus the entire kara sea will be exposed to the described processes during the fi rst 48 hours of the autumn freeze-up every year. the surface heat fl ux will decrease sometime after the fi rst 48 hours as a result of the thicker and more solid ice cover that insulates the underlying water due to its low heat conductivity. a 0.2 m thick solid ice cover with ta = –10 °c produces a heat fl ux of about 3 w/m2 (ono 1968), in contrast with the 220 w/m2 in the base case. sensitivity frasemo is tested for different forcing, a shorter fetch, for variation in the empirical aggregation factor and for fl occulation. the stratifi cation from the base case, area e 30 m, is used. because the storm case is such an important contributor to the total irs mass, the analyses are performed with this wind speed. values are tabulated in table 4 for each case. an air temperature of –20 °c increases the average upward heat fl ux from 220 w/m2 in the base case to 470 w/m2. this creates a more concentrated ice layer at the surface and down to 12 m depth. there is an increase in the irs concentration because of the higher ice concentrations. raising ta to –5 °c leads to an upward heat fl ux of 96 w/m2. at the the surface, and in the upper layer, ice concentration decreases. increasing the precipitation (snow) leads to an increased surface ice concentration and a corresponding irs increase. decreasing the precipitation decreases the surface irs concentration as well. the frazil ice size distribution is changed signifi cantly to larger crystals, which again leads to less frazil ice in the upper layer and more at the surface. the size class averaged value of the aggregation factor estimated in smedsrud (2002) was α = 0.005. this has been used in all cases up to now. the observed range of irs in the laboratory experiments gave the range 0.0003 0.1 for the empirically determined constant. using α = 0.05 makes some of the ice sink; there is 13 g/l of ice at the bottom with a density of 1900 kg/m3. in the upper layer the ice is neutrally buoyant. at the lower end of the range, α = 0.0005 makes all the ice buoyant, with a density close to 920 kg/m3. the ice has a small sediment load at all depths. to include the effect of fl occulation in a simple way, the smallest sediment size in the model (clay) is increased to 11.0 µm (same as the fi ne and medium silt). the sinking velocity is set as half way between the two classes. this does not table 4. sensitivity of frasemo to different forcing and parameters with storm winds (24 m/s). values are given at 48 hours for the surface layer. the initial stratifi cation is from 30 m depth in area e (e 30 m). name change ci max (g/l) irs (g/l) ∑ irs (kg/ m2) e 30 m, 24 m/s wind 125 11.6 4.7 cold ta = -20 °c 331 19.6 7.9 warm ta = –5 °c 30 2.8 1.1 more snow 10 mm/day 149 13.7 5.5 less snow 0.1 mm/day 151 11.3 4.5 high aggregation α = 0.05 5 0.9 12.8 low aggregation α = 0.0005 126 2.7 1.1 flocculation clay = silt 138 14.5 5.8 short fetch fetch = 5 km 60 9.1 3.7 283smedsrud 2003: polar research 22(2), 267–286 change the spm concentrations, but the size of the initial spm is larger, making the probability for collisions higher. a smaller fetch can be used to simulate the conditions in a winter polynya to some degree. a fetch of 5 km decreases the wave height to 0.95 m, compared to 3.4 m with the 100 km fetch in the base case. this decreases the sediment resuspension from the bottom. cooling of the lower layer through melting of frazil ice if the frazil ice crystals formed in the upper layer are mixed down into water slightly above the freezing point, they will start to melt. they will then melt at the in situ freezing point, and thus be able to make the water supercooled compared to the surface. this is discussed more thoroughly in smedsrud (2000). all frazil ice crystals are modelled to melt and a specifi c volume, representing a specifi c number of crystals, are transferred from a larger to a smaller size group. the model shows that it takes quite strong forcing to cool the lower layer on the kara shelf to the surface freezing point. as the upper layer reaches its freezing point, it is likely that cooling of the lower layer takes place through formation of frazil ice, as well as through inclusion of brine released during ice growth at the surface. cooling of the lower layer to its in situ freezing point can only be done by frazil ice diffusing into the lower layer. it is not clear what would happen if hybrid ice starts to melt. the process of disaggregation due to melting has not been addressed in this study. ice-rafted sediment the difference in the irs mass between the different model runs is caused by a combined effect of the spm content of the water, the volume of ice at each level and the strength of the turbulence that causes the particles to collide and aggregate. the theoretical framework was described in smedsrud (2002) and tested when the model was applied to available experimental data from a 1 m deep indoor tank. contrasts between the modelled natural setting—the kara sea—and the experimental data are highlighted below. the aggregation factor (α) is an empirical value, verifi ed on measured levels of irs up to ca. 100 mg/l (smedsrud 2001). in the present model runs, irs concentrations reach values two orders of magnitude larger than this value, at which stage the ice aggregated to sediment starts to sink. as the experimental data do not cover the high irs cases, these values should be treated with caution; they may overestimate the irs concentrations. observations of frazil ice with high sediment loads at the bottom are reported from the beaufort sea (reimnitz et al. 1987). such ice was also tentatively identifi ed in at one location (fl oe 4) in the kara shelf sea ice (smedsrud & eicken 2003), where the maximum irs concentration was 536 mg/l. such ice is called “anchor ice” if the frazil aggregates to particles at the bottom, but as the frazil ice modelled here aggregates to spm in suspension the term “sinking ice” has been used. the concentration of irs in the sampled anchor ice is higher than the theoretical value from the available area on a frazil ice disk. therefore, an upper limit of the irs concentration has not been implemented in the model. if such a limit had been introduced, sinking ice would not have been formed. the sediment used in the experiments did not come from the kara shelf, but the size distribution of the sediment in the experiment and on the kara shelf is similar. it is uncertain to what degree α could change between different types of sediment. heat fl uxes of the model and the experiment do not differ signifi cantly, supporting the assumption that the same processes govern the frazil ice growth. the base case rms velocity was 5 -10 cm/s, directly comparable to the experimental conditions. for the four experiments in smedsrud (2001) the rms velocity was in the range of 4 12 cm/s, but was mostly between 6 and 10 cm/s. in contrast, the turbulent dissipation rate in the model runs was about 50 × 10-6 w/kg, roughly ten times higher than the value of the 10 cm/s current experiment (mean ε = 3.7 × 10-6 w/kg) and ten times lower than that of the other experiments (mean ε = 380 × 10-6 w/kg) with a current of 30 cm/s. the vertical eddy viscosity (kz ) in the upper layer of the base case is about 10.0 × 10-3 m2/s. as kz is calculated based on q and ε, both in the simple case of the experiments and in the mellor– yamada turbulent closure in frasemo, this value refl ects the differences in ε. the 10 cm/s current experiment had a kz ten times larger than in the base case (ca. 110.0 × 10-3 m2/s), but in the other 284 formation of turbid ice during autumn freeze-up in the kara sea three 30 cm/s current experiments it is roughly the same: kz equals ca. 3.7 × 10-3 m2/s (smedsrud 2001). the results given in table 3 for the irs content of the fi rst kara shelf surface ice cover of the season should therefore be quite representative within the limitations of a vertical model approach. clay is known to fl occulate when it enters the ocean. this may lead to signifi cantly larger particles, in the range of 10 20 µm, which have a higher sinking velocity than a single clay particle. the sinking velocity is not as large as for the silt grains of the same size, as the fl occulated particles contain a signifi cant portion of water. if the initial spm of the upper layer were fl occulated, this would lead to a faster transformation to irs, as demonstrated in the sensitivity section. resuspension of fl occulated sediment from the bottom would probably need higher critical shear stresses. because of the greater sinking velocities, upward turbulent diffusion of fl occulated clay is less effi cient than for pure clay and this may lead to lower spm in the low wind cases. as high concentrations of resuspended sediment in the upper layer leads to sinking frazil ice in the cases with strong winds, moderately lower spm concentrations might actually lead to a higher buoyant irs mass in these cases. during the fi rst freeze-up of the season frazil ice is probably diffused down into the warmer lower layer, given a strong enough wind. here the crystals start to melt, but in these cases a large portion of the ice also becomes negatively buoyant and starts to sink. this process is not addressed in this study and it is uncertain if this combination of sinking and melting would lead to a lower or higher irs content of the surface ice. the frazil ice that sinks might actually lose most of its aggregated sediment, thereby gain buoyancy, fl oating up to the surface while still carrying a signifi cant irs mass. in the cases where the upper mixed layer stays intact, frazil ice also largely stays there and little signifi cant melting occurs, even with a warmer layer underneath. during autumn, there might actually be more than one freeze-up. the fi rst ice cover may be advected by the winds northwards towards the arctic ocean or the thin ice may be effi ciently rafted/ridged against the coast to form fast ice, thus leaving an open area further off coast. the water columns will probably become less stratifi ed, regaining their stratifi cation due to the infl ow of river water and denser water from the arctic ocean as a part of the compensating estuarine circulation. the water will now be at, or at least closer to tf than the data from september suggest and as assumed during the described cases. the modelled irs concentrations are comparable to irs measured in turbid ice on the kara shelf (smedsrud & eicken 2003). the irs concentrations from the moderate breeze are similar to the lowest values below 10 mg/l. the maximum irs concentration found in the sea ice was 2.6 g/l, and this is at the same level as the maximum irs concentrations found in this study: 10 15 g/l in the 10 m cases with the moderate breeze. in a study where the trajectories of sediment laden ice were tracked backwards from their sampling location in the central arctic ocean to the kara sea the range was 10 mg/l 10 g/l (pfi rman et al. 1997). the total values of the irs mass in table 3 are signifi cant compared to the annual river supply of 29 × 106 tonnes. the lowest value from the mean climatological winds, a moderate breeze, is 0.46 × 106 tonnes, or 1.6 % of the total discharge. so if the major portion of the ice cover freezes during a calm period, much of the sediment stays at the bottom. the situation changes drastically with a freezeup during a strong breeze, when the irs mass is comparable to 10 years of sediment discharge by rivers. this high value may indicate that major portions of the irs do not leave the kara sea. the irs fraction from the 10 m areas are very large and may indicate that this ice becomes a part of the fast ice cover, which stays in place during the winter and melts on the shelf during the spring and summer period. another explanation of the high values could be that there are signifi cantly coarser sediment in the 0 20 m depth areas and that the grain size distribution used (fig. 5) is not very representative here. this would lead to artifi cially high levels of spm and, consequently, irs as well. however, the high numbers also indicate that the export of irs holds a potential for being the major pathway out of the kara sea for the sediment discharged by the rivers. with the gale winds of the base case forcing, the total irs mass is 6.5 % of the total river discharge, there is no contribution from the 0 10 m areas and the grain size distribution should be more representative for the contributing area. for the storm and hurricane cases, the total irs mass is comparable to 10 15 years of sedi285smedsrud 2003: polar research 22(2), 267–286 ment discharge. while these are high values, it is unlikely that the freeze-up takes place during such an episode as these winds are observed only 0.43 % of the time at dikson. in these cases there are no contributions from the fast ice area, but the high values of the 30 m cases are associated with high levels of spm due to the effi cient resuspension by the waves and currents. such resuspension may be reduced if the layer below the loose surface sediment layer were compact. confi dence in the irs mass estimates presented in this work could be signifi cantly increased if more measurements of the kara shelf sediment were available. this is true for both volumes of spm (during different wind forcing) and grain size of bottom sediment in specifi c areas. conclusion formation of turbid sea ice—granular ice with incorporated ice-rafted sediment (irs)—may be effi cient on the kara sea shelf during the autumn freeze-up. in shallow areas (< 20 m depth), the process can be effective with low winds (ca. 12 m/s). in the deeper areas (> 20 m depth), the strong salinity stratifi cation implies that for an effective production of irs winds above 18 m/s or a reduced stratifi cation of the water column are needed. for the rest of the winter months there may be additional irs incorporated in ice formation in a coastal polynya. the large (200 000 km2) area is divided into three different depth zones (0 20 m, 20 40 m and 40 60 m), with two kinds of stratifi cation. the areas close to the ob and yensiey rivers have a stronger stratifi cation than the areas further north. the vertical model represents each area and during 48 h a surface slush ice cover is formed with ice concentrations typically in the range 100 200 g/l. in the mixed upper layer modelled ice concentrations are usually between 1 and 5 g/l. a freeze-up with the climatologically mean wind speed of 6 m/s incorporates 2 % of the annual sediment discharge by the ob and yenisey rivers into the ice. with higher winds some of the frazil ice crystals are aggregated to so much sediment that they gain negative buoyancy (a density > 1030 kg/m3) and sink. with moderate breeze during freeze-up, very high values of irs are produced in the 0 20 m area, comparable to 10 years of sediment discharge. this sediment probably becomes a part of the fast ice along the coast and some, or most, of it is returned to the water when the fast ice melts on the shelf during summer. as there are very little data on surface sediments from this area, the assumption of similar size here as in the deeper areas might lead to an irs mass that is too high. however, any new sediment deposited in this area over the summer will have a high probability of entering the ice as irs. for a freeze-up during a gale, about 6.5 % of the yearly sediment discharge transforms to irs. in this case results show that the ice in the shallow areas sinks due to the sediment load and the irs contribution is only from the 20 60 m depths. for a freeze-up with a storm or a hurricane, the irs mass compares to 15 years of river sediment discharge. however, the chances for such winds during the freeze-up are small. on average there are 1.6 days with such winds every year. as the strongest winds blow during the winter period, the statistical chance for a freeze-up during such an episode should be about once every 50 years. acknowledgements.—the dikson wind data are from the carbon dioxide information analysis centre (http://cdiac. esd.ornl.gov/ftp/ndp048), prepared by v. n. razuvaev, e. b. apasova and r. a. martuganov of the all-russian research institute of hydro meteorological information–world data centre. the kara sea surface salinity fi gures are from the university of washington (http://psc.apl.washington.edu/ anwap) and were originally produced at the arctic and antarctic research institute in st. petersburg. the manuscript has benefi ted from comments by carl f. forsberg, norwegian polar institute. this work was supported by transport and fate of contaminants in the northern seas, a project coordinated by the norwegian polar institute, and the research council of norway (contract no. 71928/410). references alam, a. & curry, j. a. 1998: evolution of new ice and turbulent fl uxes over freezing winter leads. j. geophys. res. 103 (c8), 15 783–15 802. alexandrov, e. i., radionov, v. f. & svyaschennikov, p. n. 2000: chapter iii. climatic regime and its changes in the region of the barents and kara seas. in transport and fate of contaminants in the northern seas. sea ice project package. aari fi nal report. st. petersburg: arctic and antarctic research institute. available on the internet at http:// npolar.no/transeff/transport/ice/. carroll, j., boisson, f., teyssie, j.-l., king, s. e., krosshavn, 286 formation of turbid ice during autumn freeze-up in the kara sea m., carroll, m. l., fowler, s. w., povinec, p. p. & baxter, m. s. 1999: distribution coeffi cients for use in risk assessment models of the kara sea. appl. radiat. isot. 51, 121–129. carroll, j. & harms, i. h. 1999: uncertainty analysis of partition coeffi cients in a radionuclide transport model. water res. 33, 2617–2626. dmitrenko, i., golovin, p. gribanov, v., kassens, h. & holeman, j. 1998: infl uence of the summer river runoff on ice formation in the kara and laptev seas. in h. t. shen (ed.): ice in surface waters. rotterdam: a. a. balkema. evenset, a., dahle, s., loring, d., skei, j., sørensen, k., cochrane, s., carroll, j. & forsberg, c. f. 1999: karex 94: an environmental survey of the kara sea and the estuaries of ob and yensiey. akvaplan-niva rep. 414.96.1006. tromsø: akvaplan-niva. gelfenbaum, g. & smith, j. d. 1986: experimental evaluation of a generalized suspended-sediment transport theory. in r. j. knight & j. r. mcclean (eds.): shelf sands and sandstones. memoir 11. pp. 133–144. calgary: canadian society of petroleum geologists. gloersen, p. campbell, w. j., cavalieri, d. j., comiso, j. c., parkison, c. l. & zwally, h. j. 1992: arctic and antarctic sea ice, 1978–1987. washington, d. c.: national aeronautics and space administration. hanzlick, d. & aagaard, k. 1980: freshwater and atlantic water in the kara sea. j. geophys. res. 85(c9), 4937– 4942. harms, i. h. & karcher, m. j. 1999: modelling the seasonal variability of hydrography and circulation in the kara sea. j. geophys. res. 104(c6), 13 431–13 448 johnson, d., mcclimans, t., king, s. & grenness, ø. 1997: fresh water masses in the kara sea during summer. j. mar. syst. 12, 127–145. kempema, e. w., reimnitz, e. & barnes, p. w. 1989: sea ice sediment entrainment and rafting in the arctic. j. sediment petrol. 59, 308–317. kowalik, z. & proshutinsky, a. y. 1994: the arctic ocean tides. in o. m. johannesen et al. (eds.): the polar oceans and their role in shaping the global environment. washington d. c.: american geophysical union. krosshavn, m., carroll, j., grennes, ø., johnson, d., king, s., johnsen, a., bjørnstad, h. & engøy, t. 1997: environmental pollution and oceanography in the arctic—epoca95. tech. rep. ffi/rapport-97/02129. oslo: norwegian defense research establishment. martin, s. & kauffman, p. 1981: a fi eld and laboratory study of wave damping by grease ice. j. glaciol. 27, 283–313. mellor, g. l. & yamada, t. 1982: development of a turbulent closure model for geophysical fl uid problems. rev. geophys. space phys. 20, 851–875. milliman, j. d. & meade, r. h. 1983: world-wide delivery of river sediments to the oceans. j. geol. 91, 1–21. nürnberg, d., wollenburg, i., dethleff, d., eicken, h., kassens, h., letzig, t., reimnitz, e. & thiede, j. 1994: sediments in arctic sea ice: implications for entrainment, transport and release. mar. geol. 119, 184–214. nygaard, e. 1995: ctd-report from karex 94. nor. polarinst. rapp.ser. 90. olso: norwegian polar institute. omstedt, a. 1985: modelling frazil ice and grease ice formation in the upper layers of the ocean. cold reg. sci. technol. 11, 87-98. ono, n. 1968: thermal properties of sea ice. low temp. sci. a23, 329–349. osterkamp, t. e. & gosink, j. p. 1984: observations and analyses of sediment-laden sea ice. in p. barnes et al. (eds.): the alaskan beufort sea: ecosystems and environments. pp. 73–93. orlando: academic press. pavlov, v. k. & pfi rman, s. l. 1995: hydrographic structure and variability of the kara sea: implication for pollutant distribution. deep sea res. ii 42, 1369–1390. pfi rman, s., colony, r., nürnberg, d., eicken, h. & rigor, i. 1997: reconstructing the origin and trajectory of drifting arctic sea ice. j. geophys. res. 102(c6), 12 575–12 586. reading, h. g. 1996: sedimentary environments: processes, facies and stratigraphy. oxford: blackwell science. reimnitz, e., kempema, e. w. & barnes, p. w. 1987: anchor ice, seabed freezing, and sediment dynamics in shallow arctic seas. j. geophys. res. 92(c13), 14 671–14 678. sherwood, c. r. 2000: numerical model of frazil-ice and suspended-sediment concentrations, and formation of sediment-laden ice in the kara sea. j. geophys. res. 105(c6), 14 061–14 080. smedsrud, l. h. 2000: frazil ice formation and incorporation of sediments into sea ice in the kara sea. phd thesis, geophysical institute, university of bergen. smedsrud, l. h. 2001: frazil ice entrainment of sediment: large tank laboratory experiments. j. glaciol. 47, 461–471. smedsrud, l. h. 2002: a model for entrainment of sediment into sea ice by aggregation between frazil ice crystals and sediment grains. j. glaciol. 48, 51–61. smedsrud, l. h. & eicken, h. 2003: report on sea-ice data for the karex 94 expedition. nor. polarinst. internrapp. ser. 15. tromsø: norwegian polar institute. svensson, u. & omstedt, a. 1998: numerical simulations of frazil ice dynamics in the upper layers of the ocean. cold reg. sci. technol. 28, 29–44. carbon exchange and primary production in a high-arctic peatland in svalbard research article carbon exchange and primary production in a high-arctic peatland in svalbard takayuki nakatsubo,1,2 mitsuru hirota,3 ayaka w. kishimoto-mo,4 noriko oura4 & masaki uchida5,6 1graduate school of integrated sciences for life, hiroshima university, higashi-hiroshima, japan 2hiroshima university museum, higashi-hiroshima, japan 3school of life and environmental science, university of tsukuba, tsukuba, japan 4institute for agro-environmental sciences, national agriculture and food research organization, tsukuba, japan 5national institute of polar research, tachikawa, japan 6school of multidisciplinary sciences, the graduate university for advanced studies, tachikawa, japan abstract moss tundra with a thick peat layer dominated by bryophytes is one of the most important ecosystems in the high arctic of svalbard, but little is known about the carbon dynamics of moss tundra. here, we estimated the net primary production (npp) and net ecosystem production (nep) of moss tundra on brøggerhalvøya (brøgger peninsula) of north-western svalbard (79°n). the net photosynthetic and respiration rates of the two dominant moss species, calliergon richardsonii and tomenthypnum nitens, were measured under laboratory conditions. on the basis of the photosynthetic and respiration characteristics and climatic data, we estimated the cumulative npp of the dominant moss species during the growing season to be 143–207 gc m-2. net co2 exchange, which was determined by subtracting the respiration of the brown moss layer from npp, was similar to that estimated using field gas flux measurements. the field measurements indicated that methane emissions contributed little to carbon flow. the nep estimated in this study was much larger than the long-term carbon accumulation rate reported in a previous study. these data suggest that a significant amount of fixed carbon was lost from the peat layer or that carbon accumulation has recently increased. the npp and nep values of the moss tundra are larger than those reported for other vegetation types in this area, suggesting that moss tundra is an active site with high rates of carbon fixation. keywords carbon flow; moss tundra; photosynthesis; respiration; calliergon richardsonii; tomenthypnum nitens abbreviations bp: before present (0 cal bp = ad 1950) nep: net ecosystem production npp: net primary production orp: oxidation-reduction potential ppfd: photosynthetic photon flux density pvc: polyvinyl chloride   citation: polar research 2023, 42, 8541, http://dx.doi.org/10.33265/polar.v42.8541 copyright: polar research 2023. © 2023 t. nakatsubo et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 30 march 2023 competing interests and funding: the authors report no conflict of interest. this study was partly supported by grants-in-aid for scientific research (nos. 20405010, 24405009, 16h05622 and 22h03734) from the japan society for the promotion of science (jsps). this study was a contribution to the project arcs ii (arctic challenge for sustainability ii, programme grant no. jpmxd1420318865) supported by the ministry of education, culture, sports, science and technology, japan. correspondence: takayuki nakatsubo, graduate school of integrated sciences for life, hiroshima university, higashi-hiroshima, 739-8521, japan. e-mail: kuyakat@hiroshima-u.ac.jp to access the supplementary material, please visit the article landing page   introduction northern peatlands represent one of the largest carbon pools in the biosphere and play a key role in the global carbon cycle (yu 2012). the recent increase in temperature in arctic regions, which is more than twice the global rate over the past 50 years (ipcc 2021), is likely to have a profound influence on the carbon pool by altering the balance between carbon accumulation and loss. carbon pools in the high arctic are likely small because of the harsh climatic conditions and lack of plant cover; however, a non-negligible amount of carbon exists in soils in areas at late successional stages (yoshitake et al. 2011). several studies have shown that there is a large amount of organic carbon in high-arctic moss tundra, which comprises moss-dominated wetlands with a thick peat layer. for example, rozema et al. (2006) reported 1-m thick peat layers dating back maximally to 5710 ± 150 bp from the moss tundra in svalbard. nakatsubo et al. (2015) estimated that 276 tonnes of organic carbon are stored in the active layer of a 40 000-m2 area (6.9 kgc m-2) of moss tundra in svalbard. because the carbon budget of moss tundra is determined by the balance between carbon accumulation and loss, analyses of these flows and the factors controlling them are needed to predict the impact of climate change on the carbon cycle in high-arctic ecosystems. however, data on the carbon flows in high-arctic peatlands are few. the aim of this study was to clarify the carbon dynamics of moss tundra, which is peatland characterized by a thick peat-forming community dominated by bryophytes (vanderpuye et al. 2002), in the high arctic of svalbard. we measured the photosynthetic characteristics of dominant moss species and the respiration of the active layer (brown moss layer) under laboratory conditions. we then modelled the npp and nep (the difference between gross primary production and total ecosystem respiration) for the growing season, using the measured photosynthetic and respiration characteristics and climatic data. it is likely that the npp and nep show considerable year-to-year variation, depending on climatic conditions that include the length of growing season. therefore, we calculated the values for three seasons using climatic data from 2012 to 2014. additionally, we measured the methane (ch4) flux at the same site and estimated the ch4 flux during the growing season because it is one of the main degradation pathways of plant polymers in high-arctic peatlands (tveit et al. 2013). methods study site the study site, stuphallet, is located in the northern part of brøggerhalvøya (brøgger peninsula), near ny-ålesund, north-western spitsbergen, svalbard (78°57′n, 11°39–40′e, 22 m a.s.l.). with a maximum width of 100 m, a swathe of moss tundra, runs along two streams: one flowing from east to west and the other from west to east between a bank and a bird-nesting cliff. the annual mean air temperature and precipitation between 2011 and 2020 in ny-ålesund, which is located approximately 7 km from the study site, were –2.9 °c and 550 mm, respectively (yr 2021). the study site was completely covered with a thick peat layer dominated by moss species such as calliergon richardsonii (mitt.) kindb., tomenthypnum nitens (hedw.) loeske, paludella squarrosa bridel, and warnstorfia exannulata (schimp.) loeske. the average thickness of the active layer (brown moss and peat) in early august 2011 was approximately 28 cm. see nakatsubo et al. (2015) for a detailed description of the study site. sample collection moss samples were collected from two dominant moss species, c. richardsonii and t. nitens, on the basis of a preliminary field survey. the samples were collected from colonies using a metal core sampler with a diameter of 5 cm in the summers of 2013 and 2015. moss cores were divided into three layers: a green (surface) layer consisting of green shoots (20–29 mm thick), a brown sub-surface layer consisting of brown shoots (40–64 mm thick) and a peat layer consisting of fragmented shoots. most of the peat layer was under the water table (waterlogged). samples of the green and brown layers were immediately brought to the laboratory in ny-ålesund and placed in cylindrical plastic cases (ø: 5 cm, height: 10 cm). they were then stored in an incubator at 5 °c under continuous light after taking fresh weight measurements. during measurements, the water content of the moss samples was maintained at 330–390% (w/w), which corresponds to the water content of moss under field conditions at our study site. photosynthesis and respiration measurements we measured the net photosynthetic rate (pn), dark respiration (r) of the green moss layer, and dark respiration of the brown moss layer (rb) using an open-flow gas exchange system with a li-cor biosciences infrared gas analyser (model li-6262). uchida et al. (2002) described the system in detail. we placed a plastic case containing the sample into a cylindrical transparent chamber (ø: 7 cm, height: 4 cm). the chamber was submerged in a water bath with a temperature control unit to maintain target temperatures within an accuracy of ± 0.2 °c. ambient air containing 390–400 ppmv co2 was introduced into the system at a rate of 300 ml min-1, and a hayashi tokei kogyo 180-w metal halide lamp (model la-180me) supplied light. unless otherwise noted, the temperature in the chamber and ppfd were maintained at 7.0 ± 0.2 °c and 1500 ± 30 µmol photons m–2 s–1, respectively. the effect of ppfd on pn was determined by reducing the incident ppfd on the chamber. samples (n = 6) were illuminated at each level of ppfd for at least three minutes before pn was measured. to examine the effect of temperature on pn and r, the moss temperature in the chamber was reduced in a stepwise manner from 23 to 2 °c at 5–6 °c intervals (n = 6). the temperature was maintained at each step for at least 30 minutes to allow gas exchange rates to stabilize. after measurements were taken, the samples were freeze-dried for dry weight determination. the effect of temperature on rb (dark respiration of the brown moss layer) was also measured in the same manner described here (n = 10). estimation of moss production we estimated the npp and nep on the basis of the photosynthesis and respiration characteristics and climatic data. at our study site, site-to-site variation in species composition was considerable. given the difficulty of determining the relative abundance of each species across the entire study area, we used the average values of the photosynthetic and respiration characteristics of the two species to estimate npp and nep values (table 1). table 1 coefficients and standard values used for the model for the estimation of the green layer and brown layer. coeffiecients and standard values calliergon richardsonii tomenthypnum nitens average green layer aa −0.0017 −0.0009 −0.0014 ba 0.0257 0.0133 0.0214 ca 0.8052 0.9117 0.8419 sb 0.0051 0.0087 0.0061 pn(7) 0.7863 0.4139 0.6001 r(7) 0.1680 0.0616 0.1148 pg(7) 0.9543 0.4755 0.7149 q10c 2.4 2.3 2.4 brown layer rb(7) 0.0456 0.0202 0.0329 q10bd 2.2 2.4 2.2 acoefficients of the temperature–photosynthetic curve (eqn. 2). bthe coefficient of the light–photosynthetic curve (eqn. 4). can indicator of the temperature sensitivity of the respiration rate of the green layer (eqn. 3). dan indicator of the temperature sensitivity of the respiration of the brown layer (eqn. 8). npp of mosses was estimated using a slightly modified version of the model described by nakatsubo (2002), who examined the environmental dependence of photosynthetic production. here, we assumed that the moss water content did not affect photosynthetic and respiration activities because water was supplied continuously on the moss tundra. the water content of the mosses was consistently high (701 ± 237% for c. richardsonii and 398 ± 106% for t. nitens) during in situ gas exchange measurements taken from 8 jul to 9 aug 2013. we also assumed that the main environmental factors affecting npp are light and temperature (harley et al. 1989; frolking et al. 2002; uchida et al. 2002). all moss samples were exposed to standard light and temperature conditions (light saturation at ppfd = 1500 µmol m-2 s-1 and 7 °c, respectively). where pg(t) is the gross photosynthetic rate at light saturation and t°c (mgco2-c g-1 h-1); pn(t) is the net photosynthetic rate at light saturation and t°c; r(t) is the respiration rate at t°c; q10 (an indicator of temperature sensitivity) is shown for the green moss layer; pg(i, t) and pn(i, t) are the gross and net photosynthetic rate at i µmol m-2 s-1 ppfd and t°c (mgco2-c g-1 h-1), respectively; and pg(7), pn(7), and r(7) are pg, pn, and r at 7 °c, respectively. a, b and c are the coefficients of the temperature-photosynthetic curve; s is the coefficient of the light-photosynthetic curve; and nppw(gc g-1) is the cumulative npp during the growing season. the effect of temperature (tb) on the respiration of the brown moss layer (rb) was determined using eqn. 8. where rb(7) is rb at 7 °c, and q10b is the q10 of respiration of the brown moss layer. finally, the nep during the growing season (nepw;gco2-c g-1) was calculated as follows: npp and nep during the growing season were converted from a dry weight basis (gco2-c g-1) to an areal basis (npp and nep; gco2-c m-2) using the average weights of the green moss layer (287 g dry wt. m-2) and average weights of the brown moss layer (1582 g dry wt. m-2). hourly ppfd and temperature data of the green and brown moss layer from 2012 to 2014 were used to estimate nep. ppfd was measured using a kona system data logger (model kadec-up) with a li-cor quantum sensor (model li-190sa) placed at the japanese base in ny-ålesund. temperatures in the green (2 cm below the moss surface) and brown (5 cm below the moss surface) moss layers were measured using hobo temperature data loggers (model tidbit v2) placed in the moss tundra. the growing season was defined as the period when the temperature of the moss layers was above 0 °c. in situ gas exchange measurements net co2 exchange was determined in the field from 8 jul to 9 aug 2013 using the static closed-chamber method described by hirota et al. (2010). we established four plots every 20 m along an 80-m transect across the moss tundra, in accordance with the method used by nakatsubo et al. (2015) and placed three pvc collars 2 cm into the ground in the moss tundra in each plot two days before measurements were initiated. each of the collars in each plot was separated by more than 1 m. the chamber (20 cm in diameter and 12.5 cm in height), made of transparent pvc pipe with a top plate and open bottom, was placed on the collar just prior to the start of the in situ co2 exchange measurements. net co2 exchange rates were determined by monitoring changes in the co2 concentration within the chamber with a vaisala co2 probe (model gmp 343). during measurements, the ppfd outside the chamber and temperature and humidity in the chamber were recorded. a small fan was placed in the chamber to mix (circulate) the air. we placed a black screen on the chamber to determine ecosystem respiration (re). the response of the gas exchange rate to light conditions was determined by decreasing the ppfd using a translucent polyethylene sheet. it took approximately five to 15 minutes for the flux rates to stabilize during each measurement. net co2 exchange rates for 8–12 plots were recorded each measurement day. all measurements were made between 11:00 and 19:00. ch4 flux was measured using a chamber of the same size and period. the chamber was made of opaque pvc without any sensors. we placed four chambers on the collar just prior to the measurements and took air (25 ml) into the chamber four times at 4–5-minute intervals. the air was collected into pre-evacuated glass vials and brought to japan. we determined the ch4 concentration using a shimadzu gas chromatograph (model gc-14b) with a thermal conductivity detector and a flame ionization detector. calibration of the gc-14b was conducted using two concentrations of ch4 standards (1.254–2.013 ppmv). the ch4 concentrations from each chamber were plotted against the sampling time, and the data were fitted with linear regression lines to determine changes in ch4 concentrations (r2 ≥ 0.90). hayashi et al. (2014) described the flux calculations in detail. while taking air samples, we measured the water table and orp in each plot. pvc pipe (ø: 5 cm, length: 40 cm) with holes drilled in four directions (ø: 5 mm, every 3 cm) was installed in each plot two days before measurements. the water table in the pipe was observed. the orp measurements were conducted using a satotech portable eh meter (model yk-23rp-adv) by inserting the platinum electrode into the peat layer. we cut the green part of the moss in the chambers after taking the final measurement on 9 aug 2013, and the fresh weight and dry weight (after freeze-drying to constant weight) of these samples were determined in ny-ålesund. statistical analyses all data were presented as mean ± standard deviations unless otherwise specified. all statistical tests were performed using statview 4.0 software (abacus concepts). we used standard statistical approaches for regression analysis to test the significance of the regression equations, and the significance of the relationships between gas exchange rates and environmental factors. results photosynthesis and respiration of mosses the maximum pn at light saturation (ppfd = 1500 µmol m-2 s-1) and 7 °c was higher in c. richardsonii (0.8 ± 0.1 mgco2-c g-1 h-1) than in t. nitens (0.4 ± 0.05 mgco2-c g-1 h-1) (fig. 1). pn of c. richardsonii at light saturation (1500 µmol m-2 s-1) was highest at approximately 7 °c and decreased at 23 °c (fig. 2). the optimum temperature for pn of t. nitens was unclear; however, pn was lower at high temperatures. dark respiration rates of the green moss layer and the brown moss layer (fig. 3) of the two species increased exponentially with temperature; q10 values ranged from 2.2 to 2.4 (table 1). fig. 1 light–net photosynthesis curves of calliergon richardsonii and tomenthypnum nitens. temperature: 7.0 ± 0.2 °c. each value is the mean of three samples with sd. fig. 2 effect of temperature on the net photosynthetic rate of calliergon richardsonii and tomenthypnum nitens. ppfd: 1500 ± 30 µmol photons m-2 s-1. each value is the mean of three samples with sd. fig. 3 effect of temperature on the dark respiration rate of the green and brown moss layer of calliergon richardsonii and tomenthypnum nitens. each value is the mean of three samples with sd. gas exchange in the field net co2 exchange rates determined on the moss surface under natural light conditions ranged from -6 to 173 mgco2-c m-2 h-1 (fig. 4). nep appeared to be regulated by natural light conditions (fig. 5a); however, temperature conditions varied in the field. there was no clear relationship between air temperature and ecosystem respiration (fig. 5b). fig. 4 nep and ecosystem respiration (re) at the study site in summer 2013. each value is the mean with sd (n = 8–12). fig. 5 (a) effect of ppfd on the net co2 exchange and (b) the effect of air temperature on ecosystem respiration in the field in summer 2013. the ch4 emission rates from the moss tundra were low and ranged from 9 to 65 µgch4-c m-2 h-1 (data not shown) (average: 34 µgch4-c m-2 h-1). there was no significant relationship between ch4 flux and environmental factors such as temperature, water table and orp (p>0.05). estimation of npp and nep in the growing season we estimated nep values by subtracting the respiration of the brown moss layer from npp values (eqn. 9); we then compared them with the nep values determined by gas flux measurements in the field (fig. 6). for this comparison, nep values under the artificially decreased light conditions were included. there was a significant relationship between the nep values estimated by the model and those measured in the field. in addition, the slope of the regression line was close to 1, indicating that our model accurately estimated nep in the field (fig. 7). fig. 6 relationship between net co2 exchange values estimated by our model and those determined in the field in four study plots (a, b, c and d). fig. 7 (a) daily npp, (b) respiration of the brown moss layer, and (c) nep in the growing season of 2013. we calculated nep for three seasons using climatic data from 2012 to 2014 (supplementary fig. s1). in these calculations, we assumed that photosynthesis and respiration activities were negligible at temperatures lower than 0 °c. npp and nep values in 2012, 2013, and 2014 were estimated to be 205, 207 and 143 gc m-2 and 88, 86 and 67 gc m-2, respectively (fig. 8). npp and nep values in 2012 and 2013 were similar, whereas npp and nep values in 2014 were lower than those in 2012 and 2013. variation in the length of the growing season among sample years is the most likely explanation for these differences. also, the growing degree days above 5 °c reflect the variation of the growing season length with values of 123, 140 and 57 in 2012–2014. the timing of snowmelt was delayed by over three weeks in 2014 compared with that in previous years (supplementary fig. s1b). thus, the growing season in 2014 (75 days) was approximately two-thirds the length of the growing seasons in 2012 (104 days) and 2013 (110 days). fig. 8 estimation of npp and nep in moss tundra during the growing season. discussion npp and nep estimated by our model varied among three years (2012, 2013 and 2014), and the most marked difference was in the npp and nep values of 2014, which were lower than those for 2012 and 2013. previous studies (uchida et al. 2002: uchida et al. 2006; yoshitake et al. 2010) have reported that the annual production of cryptogams (mosses, lichens, and the soil crust) in the high arctic shows considerable year-to-year variation depending on climatic conditions. pn values at light saturation of the two tundra moss species (0.41–0.79 mgco2-c g-1 h-1) were similar to or somewhat higher than those reported for sanionia uncinata (hedw.) loeske on a glacier foreland in ny-ålesund, svalbard (0.45 ± 0.07 mgco2-c g-1 h-1) (uchida et al. 2002). however, npp of the moss tundra during the growing season estimated in this study (143–207 gc m-2) was much larger than the npp of a sanionia colony (100% moss coverage) on a glacier foreland (0.5–14 gc m-2; uchida et al. 2002). the low npp of s. uncinata can be largely explained by the low water availability on the glacier foreland because high photosynthetic activity has been observed only on rainy days or soon after rainfall (uchida et al. 2002). the values of npp estimated in this study were similar to or larger than those reported for calliergon stramineum (brid.) kindb. in the tundra of hornsund fiord, svalbard (77°00′n, 15°33′e), which were measured by a harvesting method (220–270 g dry weight m-2 yr-1; opaliński 1991). the npp values of mosses were larger than the npp values reported for other vegetation types in svalbard. for example, during the growing season, the npp of the polar willow (salix polaris wahlenb.), which has the highest productivity among the vascular plants dominant on svalbard’s glacier forelands (muraoka et al. 2008), was estimated to be 26.1 gc m-2 (53% plant cover; muraoka et al. 2002). the higher npp of mosses can be explained by differences in photosynthetic activity during the growing season; mosses are perennial evergreen plants that can photosynthesize in the autumn if water and light conditions are suitable for photosynthesis (uchida et al. 2010). by contrast, the foliage period of s. polaris is much shorter (43 days) in this area (muraoka et al. 2002). model estimates of productivity are prone to deviation caused by measurement errors, approximations, environmental fluctuations in the field, and differences between field and laboratory conditions. we estimated nep by subtracting brown layer respiration from npp. because the co2 emissions of the peat layers were not included in this calculation, our nep values might be slightly overestimated. however, there was a strong correlation between the nep values estimated by our model and those measured in the field, indicating that the respiration of the peat layer was low. co2 emissions at sub-zero temperatures pose another difficulty in estimating nep. in this study, the growing season was defined as the period when the temperature of the moss layers was above 0 °c, assuming that photosynthesis and respiration at sub-zero temperatures were negligible. however, some studies have reported that the physiological activities of polar bryophytes continue at temperatures below 0 °c (longton 1988). because light conditions in autumn and winter were insufficient for maintaining positive net photosynthesis (see fig. 1, supplementary fig. s1), our assumption may have resulted in the overestimation of annual nep. positive nep may be possible in the spring when more light is available; however, the carbon balance depends on the thickness of the snow cover. reported values of nep in high-arctic ecosystems vary widely (table 2). nep values in this study (67–88 gc m-2) were high but similar to those of a mixed dry and wet area in longyearbyen, svalbard (82 gc m-2; pirk et al. 2017) and lake hazen, ellesmere island, canada (79 gc m-2; emmerton et al. 2016). table 2 nep in the high arctic. site latitude longitude habitat condition/vegetation type dominant species nep (gc m-2 yr-1) references ny-ålesund, svalbard 78°57′n 11°40′e moss tundra (wet) calliergon richardsonii, tomenthypnum nitens 67 to 88b this study zackenberg, greenland 74°28′n 20°34′w heath cassiope tetragona 15 zhang et al. 2018 zackenberg, greenland 74°28′n 20°34′w heath cassiope tetragona, dryas integrifolia 1 to 23a groendahl et al. 2007 alexandra fiord, canada 78°54′n 75°55′w dry salix arctica, dryas integrifolia 6 welker et al. 2004 alexandra fiord, canada 78°54′n 75°55′w mesic cassiope tetragona, dryas integrifolia −18 welker et al. 2004 alexandra fiord, canada 78°54′n 75°55′w wet eriophorum angustifolium, carex stans 15 welker et al. 2004 lake hazen, canada 81°08′n 71°04′w polar semi-desert upland (dry) dryas integrifolia, carex nardina 0b emmerton et al. 2016 lake hazen, canada 81°08′n 71°04′w meadow (wet) carex spp., eriophorum spp. 79b emmerton et al. 2016 longyearbyen, svalbard 78°11′n 15°55′e mixed dry and wet area salix polaris, eriophorum scheuchzeri 82 pirk et al. 2017 ny-ålesund, svalbard 78°55′n 11°57′e polar semi-desert (dry) salix polaris, sanionia uncinata 0 lüers et al. 2014 ny-ålesund, svalbard 78°55′n 11°57′e polar semi-desert (dry) saxifraga oppositifolia, cetraria delisei 9a lloyd 2001a ny-ålesund, svalbard 78°56′n 11°55′e heath, snowbed saxifraga oppositifolia, drepanocladus spp. −5 to 5b lloyd 2001b ny-ålesund, svalbard 78°55′n 11°50′e polar semi-desert (dry) salix polaris, sanionia uncinata 2 to 19b uchida et al. 2016 aone growing season. bone summer season. the relationships of npp and nep in moss tundra with the carbon accumulation rate can be described by the following equations (nakatsubo et al. 2015): where rpeat is the peat layer respiration (respiration of the brown layer in this study) and closs is the carbon loss other than respiratory loss (e.g., leaching) from the peat and dead moss layer. although ch4 flux can also contribute to carbon flow, its contribution to total carbon flow is likely negligible at our study site. if the maximum ch4 efflux rate observed in the field (65 µgch4-c m-2 h-1) were sustained throughout one growing season, total ch4 emissions from the moss tundra would be less than 0.2 gc m-2. nakatsubo et al. (2015) estimated the apparent rates of carbon accumulation to be 9.0–19.2 (gc m-2 yr-1) based on the 14c age and the amount of peat in the active layer. nep during the growing season estimated in this study (67–88 gc m-2) was much greater than the apparent rates of carbon accumulation at this study site. this may indicate that a significant proportion of fixed carbon was lost from the peat and dead moss layers as dissolved carbon (closs). previous studies have demonstrated that the loss of carbon via organic carbon export is an important component of the carbon balance of northern peatland (roulet et al. 2007). although there are cases in which the lateral carbon export is less relevant compared with the vertical carbon fluxes (beckebanze et al. 2022), billett et al. (2004) reported that net carbon loss in drainage water, including both the downstream flux and evasion of co2 from the stream surface to the atmosphere, was greater than or equal to the net annual carbon uptake stemming from photosynthesis/respiration at the land surface in a lowland temperate peatland catchment. although no published data are available for svalbard, a significant proportion of fixed carbon is likely lost through water flow. another factor that requires consideration is the recent warming trend. nordli et al. (2020) reported that the rate of warming since 1991 at svalbard airport is 1.7 °c/decade, which is more than twice the arctic average and approximately seven times the global average for the same period. they also reported that the number of days warmer than 0 and 5 °c has increased by 25 (21%) and 22 (59%), respectively, per year compared with that during the 1961–1990 standard normal period for 1991–2018 (nordli et al. 2020). these changes lengthen the growing season, which affects productivity. conclusion previous studies have shown that moss tundra plays an important role in carbon sequestration and carbon storage in the high-arctic terrestrial ecosystem (rozema et al. 2006; nakatsubo et al. 2015). our results indicate that the productivity of moss tundra is high compared with that of other vegetation types in this area, which confirms that moss tundra has a significant effect on regional carbon dynamics. nep is currently much larger than the carbon accumulation rates reported for this study site. one possible explanation for the difference between nep and carbon accumulation is that a significant proportion of fixed carbon is lost from the peat layer. arctic rivers are known to transport large quantities of organic and inorganic carbon to the arctic ocean (holmes et al. 2008; lougheed et al. 2020; mcgovern et al. 2020). if this is also true for the streams that flow through high-arctic moss tundra, this pathway may have a significant impact on coastal waters. the recent warming trend will also likely affect the productivity of moss tundra. moss tundra is dominated by evergreen perennial plants that have the potential to be photosynthetically active throughout the year; therefore, these plants will likely respond directly to future climate change by increasing their photosynthetic activity. acknowledgements the authors would like to thank yasuo iimura (the university of shiga prefecture) for assistance with fieldwork. this work is a contribution to the international arctic science committee (iasc) project t-mosaic (terrestrial multidisciplinary distributed observatories for the study of arctic connections). we thank edanz (https://jp.edanz.com/ac) for editing the english text of a draft of this manuscript. references beckebanze l., runkle b.r.k., walz j., wille c., holl d., helbig m., boike j., sachs t. & kutzbach l. 2022. lateral carbon export has low impact on the net ecosystem carbon balance of a polygonal tundra catchment. biogeosciences 19, 3863–3876, doi: 10.5194/bg-19-3863-2022. billett m.f., palmer s.m., hope d., deacon c., storeton-west r., hargreaves k.j., flechard c. & fowler d. 2004. linking land–atmosphere–stream carbon fluxes in a lowland peatland system. global biogeochemical cycles 18, gb1024, doi: 10.1029/2003gb002058. emmerton c.a., st. louis v.l., humphreys e.r., gamon j.a., barker j.d. & pastorello g.z. 2016. net ecosystem exchange of co2 with rapidly changing high arctic landscapes. global change biology 22, 1185–1200, doi: 10.1111/gcb.13064. frolking s., roulet n.t., moore t.r., lafleur p.m., bubier j.l. & crill p.m. 2002. modeling seasonal to annual carbon balance of mer bleue bog, ontario, canada. global biogeochemical cycles 16, article no. 1030, doi: 10.1029/2001gb001457. groendahl l., friborg t. & soegaard h. 2007. temperature and snow-melt controls on interannual variability in carbon exchange in the high arctic. theoretical and applied climatology 88, 111–125, doi: 10.1007/s00704-005-0228-y. harley p.c., tenhunen j.d., murray k.j. & beyers j. 1989. irradiance and temperature effects on photosynthesis of tussock tundra sphagnum mosses from the foothills of the philip smith mountains, alaska. oecologia 79, 251–259, doi: 10.1007/bf00388485. hayashi k., cooper e.j., loonen m.j.j.e., kishimoto-mo a.w., motohka t., uchida m. & nakatsubo t. 2014. potential role of svalbard reindeer winter droppings in atmosphere–land exchanges of methane and nitrous oxide during summer. polar science 8, 196–206, doi: 10.1016/j.polar.2013.11.002. hirota m., zhang p., gu s., shen h., kuriyama t., li y. & tang y. 2010. small-scale variation in ecosystem co2 fluxes in an alpine meadow depends on plant biomass and species richness. journal of plant research 123, 531–541, doi: 10.1007/s10265-010-0315-8. holmes r.m., mcclelland j.w., raymond p.a., frazer b.b., peterson b.j. & stieglitz m. 2008. lability of doc transported by alaskan rivers to the arctic ocean. geophysical research letters 35, l03402, doi: 10.1029/2007gl032837. ipcc (intergovernmental panel on climate change) 2021. climate change 2021: the physical science basis. contribution of working group i to the sixth assessment report of the intergovernmental panel on climate change. v. masson-delmotte et al. (eds.). cambridge: cambridge university press. lloyd c. 2001a. on the physical controls of the carbon dioxide balance at a high arctic site in svalbard. theoretical and applied climatology 70, 167–182, doi: 10.1007/s007040170013. lloyd c. 2001b. the measurement and modelling of the carbon dioxide exchange at a high arctic site in svalbard. global change biology 7, 405–426, doi: 10.1046/j.1365-2486.2001.00422.x. longton r.e. 1988. biology of polar bryophytes and lichens. avon: cambridge university press. lougheed v.l., tweedie c.e., andresen c.g., armendariz a.m., escarzaga s.m. & tarin g. 2020. patterns and drivers of carbon dioxide concentrations in aquatic ecosystems of the arctic coastal tundra. global biogeochemical cycles 34, e2020gb006552, doi: 10.1029/2020gb006552. lüers j., westermann s., piel k. & boike j. 2014. annual co2 budget and seasonal co2 exchange signals at a high arctic permafrost site on spitsbergen, svalbard archipelago. biogeosciences 11, 6307–6322, doi: 10.5194/bg-11-6307-2014. mcgovern m., pavlov a.k., deininger a., granskog m.a., leu e., søreide j.e. & poste a.e. 2020. terrestrial inputs drive seasonality in organic matter and nutrient biogeochemistry in a high arctic fjord system (isfjorden, svalbard). frontiers in marine science 7, article no. 542563, doi: 10.3389/fmars.2020.542563. muraoka h., noda h., uchida u., ohtsuka t., koizumi h. & nakatsubo t. 2008. photosynthetic characteristics and biomass distribution of the dominant vascular plant species in a high arctic tundra ecosystem, ny-ålesund, svalbard: implications for their role in ecosystem carbon gain. journal of plant research 121, 137–145, doi: 10.1007/s10265-007-0134-8. muraoka h., uchida m., mishio m., nakatsubo t., kanda h. & koizumi h. 2002. leaf photosynthetic characteristics and net primary production of the polar willow (salix polaris) in a high arctic polar semi-desert, ny-ålesund, svalbard. canadian journal of botany 80, 1193–1202, doi: 10.1139/b02-108. nakatsubo t. 2002. predicting the impact of climatic warming on the carbon balance of the moss sanionia uncinata on a maritime antarctic island. journal of plant research 115, 99–106, doi: 10.1007/s102650200014. nakatsubo t., uchida m., sasaki a., kondo m., yoshitake s. & kanda h. 2015. carbon accumulation rate of peatland in the high arctic, svalbard: implications for carbon sequestration. polar science 9, 267–275, doi: 10.1016/j.polar.2014.12.002. nordli ø., wyszyński p., gjelten h.m., isaksen k., łupikasza e., niedźwiedź t. & przybylak r. 2020. revisiting the extended svalbard airport monthly temperature series, and the compiled corresponding daily series 1898–2018. polar research 39, article no. 3614, doi: 10.33265/polar.v39.3614. opaliński k.w. 1991. primary production and organic matter destruction in spitsbergen tundra. polish polar research 12, 419–434. pirk n., sievers j., mertes j., parmentier f.-j.w., mastepanov m. & christensen t.r. 2017. spatial variability of co2 uptake in polygonal tundra: assessing low-frequency disturbances in eddy covariance flux estimates. biogeosciences 14, 3157–3169, doi: 10.5194/bg-14-3157-2017. roulet n.t., lafleur p.m., richard p.j.h., moore t.r., humphreys e.r. & bubier j. 2007. contemporary carbon balance and late holocene carbon accumulation in a northern peatland. global change biology 13, 397–411, doi: 10.1111/j.1365-2486.2006.01292.x. rozema j., boelen p., doorenbosch m., bohncke s., blokker p., boekel c., broekman r.a. & konert m. 2006. a vegetation, climate and environment reconstruction based on palynological analyses of high arctic tundra peat cores (5000–6000 years bp) from svalbard. plant ecology 182, 155–173, doi: 10.1007/s11258-005-9024-0. tveit a., schwacke r., svenning m. & urich t. 2013. organic carbon transformations in high-arctic peat soils: key functions and microorganisms. the isme journal 7, 299–311, doi: 10.1038/ismej.2012.99. uchida m., kishimoto a., muraoka h., nakatsubo t., kanda h. & koizumi h. 2010. seasonal shift in factors controlling net ecosystem production in a high arctic terrestrial ecosystem. journal of plant research 123, 79–85, doi: 10.1007/s10265-009-0260-6. uchida m., muraoka h. & nakatsubo t. 2016. sensitivity analysis of ecosystem co2 exchange to climate change in high arctic tundra using an ecological process-based model. polar biology 39, 251–265, doi: 10.1007/s00300-015-1777-x. uchida m., muraoka h., nakatsubo t., bekku y., ueno t., kanda h. & koizumi h. 2002. net photosynthesis, respiration, and production of the moss sanionia uncinata on a glacier foreland in the high arctic, ny-ålesund, svalbard. arctic, antarctic, and alpine research 34, 287–292, doi: 10.1080/15230430.2002.12003496. uchida m., nakatsubo t., kanda h. & koizumi h. 2006. estimation of the annual primary production of the lichen cetrariella delisei in a glacier foreland in the high arctic, ny-ålesund, svalbard. polar research 25, 39–49, doi: 10.3402/polar.v25i1.6237. vanderpuye a.w., elvebakk a. & nilsen l. 2002. plant communities along environmental gradients of high-arctic mires in sassendalen, svalbard. journal of vegetation science 13, 875–884, doi: 10.1111/j.1654-1103.2002.tb02117.x. welker j.m., fahnestock j.t., henry g.h.r., o’dea k.w. & chimner r.a. 2004. co2 exchange in three canadian high arctic ecosystems: response to long-term experimental warming. global change biology 10, 1981–1995, doi: 10.1111/j.1365-2486.2004.00857.x. yoshitake s., uchida m., koizumi h., kanda h. & nakatsubo t. 2010. production of biological soil crusts in the early stage of primary succession on a high arctic glacier foreland. new phytologist 186, 451–460, doi: 10.1111/j.1469-8137.2010.03180.x. yoshitake s., uchida m., ohtsuka t., kanda h., koizumi h. & nakatsubo t. 2011. vegetation development and carbon storage on a glacier foreland in the high arctic, ny-ålesund, svalbard. polar science 5, 391–397, doi: 10.1016/j.polar.2011.03.002. yr 2021. ny-ålesund. (weather data.) accessed on the internet at https://www.yr.no/en/statistics/graph/5-99910/norway/svalbard/svalbard/ny-ålesund on 24 may 2021 yu z.c. 2012. northern peat land carbon stocks and dynamics: a review. biogeosciences 9, 4071–4085, doi: 10.5194/bg-9-4071-2012. zhang w., jansson p.-e., schurgers g., hollesen j., lund m., abermann j. & elberling b. 2018. process-oriented modeling of a high arctic tundra ecosystem: long-term carbon budget and ecosystem responses to interannual variations of climate. journal of geophysical research—biogeosciences 123, 1178–1196, doi: 10.1002/2017jg003956. alaska beluga whale committee—a unique model of co-management perspective alaska beluga whale committee—a unique model of co-management kathryn j. frost1, tom gray2, willie goodwin, sr.3, roswell schaeffer3 & robert suydam4 1alaska beluga whale committee, kailua-kona, hi, usa 2alaska beluga whale committee, nome, ak, usa 3kotzebue, ak, usa 4department of wildlife management, utqiaġvik, ak, usa abstract the alaska beluga whale committe (abwc) was formed in 1988 to conserve beluga whales (delphinapterus leucas) and manage beluga subsistence hunting in western and northern alaska in cooperation with the national marine fisheries service (nmfs). when the abwc was formed, there was no consistently funded research or management programme for belugas in alaska, and co-management was a new concept. the abwc brought together representatives from beluga hunting communities; federal, state, tribal and local governments; and beluga researchers to develop and implement a programme to manage belugas. with funding from nmfs and others, the abwc has collected data necessary for informed management decisions including the following: harvest data; aerial surveys of belugas in bristol bay and the eastern bering and chukchi seas; beluga tracking studies, including training hunters to attach transmitters; a pioneering genetics study of beluga stock identity that has facilitated collection of >2000 beluga skin samples; and a genetics-based mark–recapture study to estimate beluga abundance in bristol bay and validate aerial survey estimates. the abwc is currently engaged in regional management planning in kotzebue sound and the eastern bering sea. it produces results that are scientifically valid, locally accepted and cost-effective and is an example of what can be achieved when native hunters, scientists and managing agencies respect and listen to one another and work together. however, the current nmfs co-management funding process has fundamentally altered the relationship between nmfs and abwc, with nmfs now acting more like a funding agency than a partner. this article is part of the special cluster beluga whales (delphinapterus leucas): knowledge from the wild, human care and tek, which has been funded by mystic aquarium, caff and the norwegian ministry of climate and environment. keywords subsistence; delphinapterus leucas; collaboration, alaska natives abbreviations abwc: alaska beluga whale committee adfg: alaska department of fish and game ano: alaska native organization 2ebs: eastern bering sea iwc: international whaling commission mmpa: us marine mammal protection act (1972; us public law 92-522) nmfs: us national marine fisheries service nsb: north slope borough (municipal government in northernmost alaska)   citation: polar research 2021, 40, 5611, http://dx.doi.org/10.33265/polar.v40.5611 copyright: polar research 2021. © 2021 k.j. frost et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 18 november 2021 competing interests and funding: frost, gray and suydam are affiliated with the abwc. schaeffer and goodwin are past abwc chairmen. funding was provided regularly by the nmfs to the abwc, with additional financial and in-kind support by the nsb and the adfg. the adfg division of wildlife contributed early meeting support, logistics and salaries for the involvement of adfg staff in meetings and research activities. commitment from senator ted stevens was critical. funding prior to 1992 was obtained from the bureau of ocean energy management (then called minerals management service) and the bureau of indian affairs. correspondence to: kathryn j. frost, alaska beluga whale committee, 73-4388 paiaha street, kailua-kona, 96740-9311, hi, usa. e-mail: kjfrost@hawaii.rr.com introduction indigenous communities in alaska have harvested marine mammals, including beluga whales (delphinapterus leucas), for thousands of years to help meet nutritional and cultural needs (meek 2009). in 1972, the mmpa placed a moratorium on the taking of marine mammals; however, section 101(b) of the act exempted taking by any indian, aleut or eskimo residing in alaska and dwelling on the coast of the north pacific or the arctic ocean if such taking is for subsistence purposes and occurs in a non-wasteful manner. passage of the act was followed by 10–15 years during which there was variable and often very little communication between alaska native hunters and the managing federal agencies regarding marine mammals. exceptions were the alaska eskimo whaling commission, formed in 1977, to safeguard the bowhead whale (balaena mysticetus) and its habitat and to support the whaling culture of its member communities (suydam et al. 2021), and the eskimo walrus commission, which was formed in 1978 to advocate for and represent alaska native concerns regarding federal management of walruses (odobenus rosmarus; metcalf & robards 2008). ensuring sustainable harvests is essential for the conservation of marine mammal stocks and resilience of communities dependent on the subsistence lifestyle and culture. how this is accomplished differs greatly between modern natural resource agencies and indigenous peoples. while indigenous people often encourage hunting practices and manage through cultural norms and education of young hunters, natural resource agencies establish enforceable rules and regulations around harvesting that are based on western approaches to management, such as using scientific information about population size, harvest levels and reproductive capacity (fernandez-gimenez et al. 2008; gadamus & raymond-yakoubian 2015). obtaining adequate scientific information can be a challenge in remote areas and in the face of rapid environmental and social changes in the far north. agency requirements for rigorous population estimates for management focus discussions on statistical methods and numbers but neglect ecosystem complexity and local values surrounding harvesting and may be unsuccessful in influencing the behaviour of hunters (robards et al. 2009; gadamus & raymond-yakoubian 2015). sharing responsibility for resource decision-making between the government and resource users (pinkerton 1989; singleton 1998) has emerged as one way to bridge the gap between the fundamentally different approaches of western science and indigenous culture to managing subsistence resources and achieving sustainable harvests. co-management approaches can link long-term indigenous knowledge about species and ecosystems with scientific research. combining these forms of knowledge may provide a more realistic understanding of the system than either alone (meek 2009). developing and promoting co-management organizations, which involve indigenous hunters and leaders, can facilitate the collection of data needed to make informed management decisions and for community acceptance of management protocols that are implemented. co-management is sometimes criticized by both government and the local resource users. it may be perceived as a means of expanding government authority and placating local communities rather than actually sharing power more equitably with local people (cruikshank 1998; fernandez-gimenez et al. 2008) or, in the words of hunters, “they manage, we cooperate.” some believe that co-management structures have merely been inserted into existing institutions of bureaucratic wildlife management (nadasdy 2003). in 1988, the abwc was formed with the goals of maintaining healthy populations of beluga whales, providing for adequate subsistence harvests of belugas and protecting hunting privileges for alaskan subsistence hunters (adams et al. 1993). it was formed at least partially in response to the 1977 crisis surrounding the iwc’s moratorium on subsistence hunting of bowhead whales (gambell 1993; suydam et al. 2021). although it was not formed as a formal co-management institution, the abwc wanted to demonstrate local management capacity and avoid regulation by outside groups such as the iwc. from its inception, the abwc included beluga hunters; local, state, tribal and federal government personnel; and scientists. in 1994, the mmpa was amended (section 119), so that the us federal government could enter into cooperative agreements with anos to conserve marine mammals and provide co-management of subsistence use by alaska natives. an ano was defined as a group designated by law or formally chartered, which represents or consists of indians, aleuts or eskimos residing in alaska. section 119 further stated that cooperative agreements with anos could include collecting and analysing data, monitoring harvests, participating in research and developing co-management structures with federal and state agencies. it provided a formal, legally based structure for incorporating the knowledge and perspectives of alaska natives into the research and management of marine mammals they harvest for subsistence. shortly after the section 119 became law, the abwc began to develop a formal co-management agreement with the nmfs, and in 2000, it signed an agreement for the co-management of the western alaska beluga whale population. the abwc now focuses its efforts on four officially recognized stocks: bristol bay, ebs, eastern chukchi sea and beaufort sea. it also co-manages belugas in kotzebue sound (fig. 1). fig. 1 summer ranges of beluga stocks in alaska. (courtesy of j. crawford, adfg.) the objective of this paper is to describe how the abwc works and why it remains strong and effective after more than 30 years. we do not attempt to frame a theoretical process or provide an academic description of co-management. instead, we offer explanations for why participants engage in candid discussions about difficult subjects, refer to “our studies” (not “theirs”) and above all, respect and engage with each other in a meaningful way even when opinions differ. although success may differ in the eyes of the beholder (nadasdy 2003), the abwc has succeeded in creating an environment conducive to the open exchange and discussion of information and ideas between users and managers and to blurring the distinctions between the two. abwc structure and function—why it is what it is the abwc includes tribally appointed delegates from beluga hunting communities in northern and western alaska; regional representatives; representatives (i.e., scientists and managers) of federal (nmfs), state (adfg) and regional (nsb) governments; and others as determined by the committee (adams et al. 1993; fernandez-gimenez et al. 2006). all of these are full members who vote on committee decisions, with the exception that only hunters may vote on hunting-related matters. all regular business is conducted during the meetings, with all members present. the abwc meets annually, usually in november, after most beluga hunting has ceased for the year, to facilitate collection of harvest data. the decision to include scientists and managers as well as beluga hunters as members was a formative decision that has shaped the abwc for the ensuing 30 years (adams et al. 1993). this differs from other alaska marine mammal anos, which include only alaska natives as voting members. at its first meetings, participants discussed whether the group would be a commission of native hunters with associated non-voting scientific government advisers or a committee made up of hunters, scientists and agency managers sitting as full voting members and with equal status. after extensive discussion, the group unanimously passed a resolution, stating that voting members would include representatives of coastal beluga hunting communities, the nmfs, the adfg, the nsb and others as determined and voted on by the committee. at a recent abwc meeting, when nmfs personnel expressed concern that it might be perceived as a conflict of interest if they were full voting members of the abwc, abwc chairman tom gray stated that “we need to be addressing issues together. the scientists and managers should be sitting with us at the table making decisions, not on the sidelines. this group is very different with nmfs at the table. it is easier to work together and to come up with solutions.” another abwc delegate said, “everyone has to have a stake in this, or it doesn’t mean anything. the abwc isn’t so different from the other alaska native organizations by accident. it is because we’re all members.” most marine mammal anos consist of relatively small boards with regional representation. in contrast, the abwc includes hunter-delegates from many villages. each hunter-delegate reports harvest data for his community, as well as any unusual observations and concerns. having representatives of many communities familiar with the science and the issues, not just a handful of people from regional centres, facilitates constructive discussions of potential problems, enables communication of local observations and traditional knowledge about belugas, encourages discussion of beluga issues within beluga hunting communities, and facilitates local involvement in research and harvest monitoring. the abwc has found that having hunter-delegates, rather than professional ‘meeting-goers,’ fosters communication, collaboration and positive dynamics among members. the tone of discussions is different when hunter-delegates are in the majority and when scientists and managers are engaged and respectful listeners. when a management issue arises, the abwc benefits greatly from having an informed group of local hunter-delegates who understand how the abwc works and trusts the research because they were involved in the projects and know the scientists. the dynamics and dialogue are also positively influenced by mutual respect among the delegates; everyone has an opportunity to express his thoughts and is involved in decision-making. all delegates are invested in the process and outcomes of abwc projects and efforts. the abwc has benefited from substantial stability and the long tenure of many of its delegates. four of five current members of the executive committee, six of eight agency representatives and scientists and 40% of the current regional and community delegates have served for 10 or more years. abwc membership has grown from about 20 in the early years to its current 35–40, largely in response to limited but reliably available funding from nmfs and to increased emphasis on regional management planning. at its inception, abwc meetings generally included 10 or fewer hunter-delegates. in 2019, 28 hunter-delegates attended. the abwc, unlike most other marine mammal anos, does not have an executive director. early on, delegates decided that the business of the organization would be conducted by its members rather than by hired staff. as a result, many people from different communities and organizations have worked together to organize abwc meetings, plan research, prepare proposals, collect harvest information, attend meetings and provide input on issues related to belugas. this has created a collective ‘ownership’ of abwc activities. the downside of this approach is that what the abwc can accomplish is limited by the time people have available to volunteer their efforts and contribute. the abwc has repeatedly revisited the decision not to have an executive director, and the decision has always been the same: the committee is stronger and more effective when its members, who volunteer their time, do the work. funding the abwc is fortunate to have had reliable funding since soon after its formation. it has received approximately 200 000 usd annually since 1992. this funding, as well as cooperation among members and the decision not to employ an executive director, has made it possible for the abwc to conduct its own research in addition to holding annual meetings. stability in funding has allowed the abwc to plan ahead and be proactive about research and management needs. prior to 1992, funding (mostly for meetings, a newsletter and attendance at the iwc) was from the nsb and the bureau of indian affairs, with additional support from the adfg, the nmfs, the fisheries joint management committee and the department of fisheries and oceans canada. in 1991, the abwc executive committee submitted a programme description and budget document to alaska’s senator ted stevens that was successful in securing funds for an annual meeting, attendance at the annual iwc meeting, harvest studies, genetics analysis for stock identification and aerial population surveys. from 1992 to 2000, abwc continued to receive annual funding through special congressional earmarks, which bypassed the competitive allocation process. beginning in 2001, abwc funding was added as a line item expense in the nmfs budget. to receive congressional funds from 1992 to 2010, the abwc prepared simple proposals detailing priority projects and a general budget for each. in 2011, earmarks were no longer allowed, and the federal funding process was changed in response to increased requests for federal funding by marine mammal anos. the abwc is now required to compete directly with other alaskan co-management groups for funds. since implementation, abwc funding has declined approximately 25% to an annual average of 167 000 usd, and this has reduced its ability to conduct management-related research. typically, the abwc requests funding for both research and management. this is unlike most other anos, which typically seek only management-related funding because species research is conducted by nmfs. however, the nmfs does not have a developed research programme for belugas in northern and western alaska, in large part because the abwc has coordinated, conducted or supported most beluga research through its cooperative model. the post-2011 competitive funding process for anos is cumbersome. it resembles the competitive ‘request for proposal’ process for research proposals and is not tailored for co-management groups that share management and, in the case of the abwc, research responsibilities, with nmfs. the nmfs now acts as a funding agency rather than as a partner with shared needs and responsibilities. instead of a simple and flexible description of what will be done, proposals must include components on design and management, objectives, project and administrative milestones, project and budget narratives, benefits and/or expected results, need for assistance, government activities that might be affected and the abwc’s relationship with those activities, curricula vitae, letters of endorsement and qualifications of personnel involved in projects. prior to implementation of this competitive process, abwc proposals (narrative and budgets) were about 10 pages; with all required documentation, they now average about 75 pages. budgets require federal budget forms, listing of every anticipated expense and must be accompanied by a full budget narrative describing and justifying every line-item expenditure. such budgets do not acknowledge the limited capacity and flexibility required to operate in village situations, with volunteer participants and challenging logistics. applicants for co-management support from nmfs may not request assistance or funds for proposal preparation because the nmfs is the funding agency. this presents a conundrum because co-management groups exist solely to co-manage a specified resource with nmfs and because their primary—and usually sole—source of funding is nmfs. co-management proposals are reviewed by technical advisory panels assembled by nmfs. funding decisions are made based upon the recommendations of reviewers and nmfs staff and are not collaborative or transparent. past reviewers, for example, have recommended eliminating newsletters (no reason given), even though newsletters were a top priority of the abwc delegates. in another example, rather than a general recommendation to reduce the proposed abwc meeting budget, reviewers specified (for reasons not shared with the abwc) a reduction in the number of bristol bay delegates. there was no discussion with the abwc about the rationale for determining regional representation and the abwc’s efforts to maintain regional balance as a means to address and avert future, often unanticipated, regional issues and problems. another substantial downside of the current funding process is that because nmfs personnel are voting members of the abwc and the abwc receives financial support through nmfs contracts and grants, the nmfs is concerned that there could be the appearance of conflict of interest or undue influence by the abwc on nmfs decision-making. the abwc has proposed to remedy this issue by amending its bylaws to state that: “to avoid the appearance of a conflict of interest, nmfs alaska region delegates will not vote on matters of personnel, budgets and grant application related matters.” this issue is as yet unresolved. to address the same issue, nmfs marine mammal laboratory scientists are no longer able to review abwc co-management grant funding proposals. harvest monitoring the abwc collects annual harvest data for approximately 50 communities, from bristol bay to the beaufort sea (frost & suydam 2010). the data on beluga harvests in alaska are sent annually to the nmfs for use in stock assessments. formal acknowledgment of the abwc as the source of beluga harvest data by the nmfs has provided credibility to both the data and the abwc. the abwc also provides annual harvest information for use by the iwc, of which the united states is a member. currently, the harvests of belugas, by stock, generally do not exceed 2% of estimated abundance (table 1). for bycatch of cetaceans in commercial fisheries, the nmfs generally authorizes a maximum take of no more than 2% of the population. this level of bycatch, referred to as the potential biological removal, is considered sustainable for cetaceans (wade 1998) and consistent with the goals and mandates of the mmpa. although this potential biological removal ‘rule’ was not intended to be applied to subsistence harvests by alaska natives, it, nonetheless, serves as a precautionary guideline. table 1 landed subsistence harvest of belugas in alaska by beluga stock, 2007–2019 (abwc, unpubl. data). stock 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 recent pop. est.a % of est.b beaufort sea 62 50 13 70 42 91 34 24 43 43 10 13 18 19 629 0.20 chukchi sea 121 73 50 32 32 48 81 50 71 14 38 65 29 20 752 0.26 kotzebue sound 151 1 3 2 32 4 6 10 1 9 2 15 6 no data ebs 230 119 170 174 190 183 213 236 190 176 183 187 213 9242 2.05 bristol bay 18 19 21 26 21 27 27 26 22 19 10 11 19 2040 1.00 amost recent point estimate for population size. see table 2 for more details. bpercentage of average harvest, 2007–2019, relative to the most recent point estimate of population. committee members understand the need to have accurate harvest data by stock to sustainably manage the hunt. they also recognize that this information could be ‘used against them’ by anti-whaling or animal protectionist groups. however, the abwc members concluded early on that there was strength in collecting and providing the best possible harvest data themselves, replacing inaccurate or misleading information from ‘outsiders.’ abwc policy requires that anyone using abwc harvest data must acknowledge the abwc as the source. most harvest information is reported at the abwc annual meeting. the abwc distributes harvest report forms to delegates and a variety of tribal and regional associations before the meeting. at meetings, delegates report on the harvest in their own communities and, when possible, on harvests in other nearby communities. this information is augmented by inquiries from the abwc executive committee. information from different sources is reconciled to produce the most accurate estimate of harvest. some information about the number of ‘struck-and-lost’ belugas (animals struck but not landed) is provided by abwc delegates. where netting or drive hunting is the method of take, most, if not all, belugas are retrieved. when belugas are hunted from boats in deep water, struck-and-lost belugas are more likely to occur. the abwc is working to raise awareness about the importance of collecting struck-and-lost information and encourages delegates to obtain better information. while it is unknown how many unsuccessful strikes result in mortality, struck and lost whales must be considered if the harvest is near the sustainable level. the abwc considers hunter-delegate harvest reports, verified through questionnaires, reports and other sources, to be adequate for documenting harvests of stocks that are healthy, abundant and harvested within the sustainable range. a great deal more money could be spent to conduct elaborate harvest surveys in each community, but the abwc believes the current effort is sufficient to evaluate sustainability of current harvests. because harvest monitoring has been affordable and done by the delegates, the abwc has a 31-year uninterrupted record of harvest data. such a long-term record makes it possible to detect harvest trends or unusual harvest events. when an unusual harvest event occurs, help can be requested from member agencies to support additional sampling or investigation of the event. because the alaska beluga harvest occurs in approximately 50 communities (many of which harvest only a few belugas annually), it has been difficult for the abwc to coordinate collection of biological samples. the only in-depth scientific beluga harvest study for an abwc community is the long-standing effort conducted by the nsb at point lay (suydam 2009). its main purpose has been to collect biological and health-related data. instead of extensive bio-sampling in other locations, the abwc has prioritized research concerning the basic information needed for management: genetics for stock identification, aerial surveys to determine abundance and satellite tagging to document habitat use. the abwc’s genetics stock identification studies have been conducive to sampling because only a small piece of skin is required, and sufficient sample sizes can be accumulated over multiple years. skin samples, which have been collected since 1992, can be brought to meetings or are easily mailed. in contrast, samples required for studies of reproduction or diet are much larger, harder to preserve in the field and more complicated to obtain and transport. the abwc and research all stocks of belugas co-managed by the abwc are harvested for subsistence. to sustainably manage this subsistence harvest, it is necessary not only to monitor and report harvest data but also to understand stock structure, abundance, population trend, reproduction and mortality. the climate in northern alaska is changing rapidly, particularly the extent and duration of sea-ice cover (stroeve & notz 2018; huntington et al. 2020). this may substantially impact beluga habitat in some areas. activities such as oil and gas exploration and commercial shipping are occurring at an accelerating pace in beluga habitat, belugas and humans eat the same commercially valuable salmon, and anthropogenic noise is being introduced into beluga habitat, with unknown consequences. to evaluate potential impacts of such activities and mitigate them where possible, it is necessary to have better information about habitat use, feeding, migration routes and overwintering areas. the basic research needs for most alaska marine mammal species covered by co-management agreements are being addressed by local, state and federal agencies. the us federal government, through the nmfs, supports research on ice seals (phocinae), harbour seals (phoca vitulina), bowhead whales, sea lions (eumetopias jubatus), fur seals (callorhinus ursinus) and cook inlet belugas. comparably, there is a much smaller nmfs research programme for belugas in northern and western alaska, and there was no consistently funded research programme before the abwc was established (hazard 1988). since its inception, the abwc has served as a forum for prioritizing and coordinating beluga research in alaska and sharing data, results and ideas that provide the basis for informed management. soon after it was formed, the abwc initiated a scientific research programme to acquire information needed for management: population size, stock identity and reproduction. the absence of an existing federal beluga research programme and the cooperative and inclusive nature of abwc membership facilitated development of shared priorities, joint research and an ‘abwc research programme.’ coastal hunters, who hold a large body of indigenous knowledge about beluga distribution, diet and movements, contributed—and continue to do so—their information and ideas about what studies were important and how they could be accomplished. the collaboration and cooperation among its many members, sustained funding from the federal government (i.e., the nmfs, the bureau of indian affairs and mineral management service [called the bureau of ocean energy management since 2010]) and support from the nsb, the adfg and every member, plus independent researchers, has ensured its success. meaningfully involving hunters in beluga research and management requires more than verbal commitments at meetings on the part of all parties. researchers who seek hunter participation must obtain funding to compensate involvement and take the time to train and integrate local participants into projects. hunters must not only express the desire to be involved in projects but must also follow through by being available to participate, even when it interferes with other activities. all parties must be honest—and realistic—about what is practically attainable and what is desirable but less likely to occur. the abwc has supported a variety of research, but three programmes make up the core of its research activities: aerial abundance surveys, genetics stock identification and satellite tagging. genetic stock identification and satellite tagging have been fundamentally important to the abwc, not only for the scientific information they produce but also because of the shared participation by hunters and scientists and their contribution to the ‘we’ part of science. neither project could have succeeded without the contributions of both. genetics stock identification in the formative years of the abwc, the use of molecular genetics to investigate stock identity was new and rapidly evolving. at an abwc meeting in 1989, just a year after it was formed, a proposal was made to use new genetics techniques to investigate stock structure of belugas. intrigued by the idea and undeterred by the lack of funding, hunter-delegates at the meeting proposed spending ‘leftover’ per diem money (weather had prevented some members from travelling) to support a trial genetics study. in 1992, the abwc began funding a beluga genetics study based at the nmfs southwest fisheries science center. conducted by greg o’corry-crowe and his colleagues (1997, 2002, 2016, 2018, 2020), with broad participation by beluga hunters throughout coastal alaska, the research programme that developed from that study is among the abwc’s most successful research endeavours. almost 30 years later, hunters have provided more than 2000 skin samples for genetic analysis. previously provisional stocks are now determined to be genetically discrete, and hunters are developing regional management plans for several stocks based on the information from the samples they provided. when biologists were initially considering summer concentration areas as putative stocks, hunters proposed that ‘spring’ and ‘fall’ belugas in norton sound might belong to more than one stock. this suggestion was based on their observations of differences in size and behaviour. although norton sound and yukon belugas are now considered to be part of a single ebs stock, analysis of samples from some years indicates that incursions of other stocks do, in fact, occur in fall (o’corry-crowe et al. 2016). satellite tagging and tagger training the other signature project for the abwc has been satellite tagging and hunter-tagger training. the abwc first participated in and helped to facilitate successful satellite tagging of belugas at point lay in 1998 (suydam et al. 2001). since then, it has been involved in the tagging of 101 belugas: 33 at point lay, five in the ebs and 63 in bristol bay. catching and tagging belugas in alaska requires a federal research permit. the abwc does not have its own permit but operates under the adfg’s permit. prior to the abwc’s efforts to work with and train local hunters, only scientists were listed on research permits. that changed when abwc’s delegate charles saccheus sr. participated in beluga tagging at point lay in 1999, and later in cook inlet and bristol bay. the adfg subsequently listed saccheus on its beluga tagging permit. he was the first alaska native to be so authorized. since then, hunter-taggers have been trained (with community consent) at point lay, stebbins and bristol bay, and the adfg has worked with the federal permitting office to include 10 other trained beluga hunter-taggers on its permit. abwc tagging has occurred in three forms in response to local circumstances. at point lay, belugas have been tagged by scientists primarily using their own logistics but with strong community cooperation, support, input and occasionally direct involvement. this is because tagging occurs in conjunction with the annual point lay drive hunt, in which effectively all community members are involved either in the harvest itself or processing the harvest afterwards. the methods used by scientists require cooperation and communication between hunters and scientists during the hunt and real-time agreement about when tagging may occur. scientists attend a hunter meeting to discuss their plans and seek input into how tagging should be coordinated with the drive. tagging by integrated crews of scientists and local hunters has occurred in bristol bay (citta et al. 2016) and norton sound. the two groups work together to develop and refine methods for catching belugas. extensive local knowledge about local conditions and beluga behaviour has been essential to success. independent tagging by an abwc-trained hunter–tagger first occurred in 2012. that hunter–tagger, who was trained in bristol bay, netted and satellite-tagged a beluga from the ebs near nome. the five tags deployed by this hunter–tagger since then have provided the only telemetry data on the movements, migration and overwintering areas of ebs belugas (citta et al. 2016). satellite tagging of ebs belugas was not successful before the abwc hunter–tagger programme began, despite multiple efforts to catch and tag belugas. this was largely due to the unpredictable presence of belugas, weather, limited time of scientists for tagging and the high cost of such programmes. when local hunters conduct tagging, it occurs opportunistically when conditions are right and is not restricted to a time slot when scientists are present. hunter-tagging is cost-effective because it does not require complicated logistics or salaries, travel and per diem for scientists from regional centres. the extensive local knowledge of hunters increases the chances for successful tagging. perhaps most importantly, the hunter–tagger programme builds local capacity by involving hunters in fundamental aspects of research and makes them true collaborators in beluga research, management and outreach. these projects and the derivative science become ‘our’ projects and ‘our’ science. as more local hunter–taggers are trained and more belugas are tagged, local capacity increases as well as knowledge about these beluga stocks. abundance estimates abundance estimates are important for assessing whether harvests are sustainable. the abwc has supported abundance surveys for bristol bay, ebs and eastern chukchi sea stocks since 1992. lowry et al. (2020) provided a thorough description of the most recent abundance and trend data (also see table 2). since the mid-2000s, surveys have been less frequent for a variety of reasons. the abwc is currently working with the nmfs to ensure that in the future, each stock is surveyed every 5–8 years, so that updated abundance information is available. abundance estimates generated through abwc-funded surveys or surveys conducted in cooperation with the abwc have been used by the nmfs to develop stock assessment reports. the nmfs has credited the abwc for its efforts, granting recognition of the abwc’s role in providing information necessary to ensure sustainable harvests. table 2 summary of the population estimates and trend for western and northern alaska beluga stocks. the 2011 bristol bay survey was a genetic mark–recapture estimate. all others were conducted using line-transect approaches. aerial surveys were flown in bristol bay in 1993–94, 1999–2000, 2004–05 and 2016; in the ebs in 1992–95, 1999–2000 and 2017; and in the eastern chukchi sea in 1989–1991, 1996–98, 2001–03 and 2012. surveys of the beaufort sea stock have been conducted by canadian biologists. stock year population size cva; cib trend references bristol bay 2011 1928c ci = 1611 – 2337 citta et al. 2018 2016 2040 cv = 0.26; ci = 1541 – 2702 +4.8% (1993–2005; 2016) lowry et al. 2008; citta et al. 2020 ebs 2000 6994 cv = 0.37; ci = 3162 – 15 472 lowry, zerbini et al. 2017 2017 9242 cv = 0.12 trend unknown, estimates not comparable ferguson et al. 2018; lowry et al. 2020 eastern chukchi sea 2012 20 752 cv = 0.70 lowry, kingsley et al. 2017 2012–16 (partial)d range of est. = 6813 – 16 598 range of cv = 0.47 – 0.51 stable givens et al. 2020 beaufort sea 1992e 19 629 expanded to 39 258 (allen & angliss 2015) cv = 0.229 no surveys since 1992e harwood et al. 1996 acoefficient of variation. b95% confidence interval. cgenetic mark–recapture estimate. dthese estimates account for approximately 50% of the area for the lowry, kingsley et al. (2017) estimate. etwo independent surveys were flown again in 2019; analyses are underway by canada department of fisheries and oceans and the nmfs. the adfg, with support from the abwc, conducted an innovative genetic mark–recapture abundance study in bristol bay from 2002 to 2011. the goal was to provide an independent abundance estimate. the genetic abundance estimate, which does not depend on estimating correction factors for belugas not at the surface, was consistent with aerial survey estimates (citta et al. 2018). like other abwc activities, this was a collaborative undertaking in which local beluga hunters worked together with adfg scientists to collect biopsy skin samples. hunters were familiar with the mud bars and the extreme tidal fluctuations in bristol bay and knew where to find belugas and how to approach them to obtain samples. hunter–scientist teams were able to collect as many as 150 skin samples in only a few days. management planning abwc management plan creation of a beluga management plan was an abwc priority from the earliest meetings. a team was appointed to draft the first version of an alaska beluga whale management plan in 1989. the plan included sections on goals (the same as those of the abwc), conservation, harvesting, use, reporting and monitoring, public involvement, research and enforcement. it was reviewed at multiple abwc meetings, and delegates from more than 25 alaska communities were part of the review process. a draft plan was adopted unanimously by the abwc delegates in late 1990. the abwc’s efforts to develop a management plan were voluntary and self-initiated. for this reason, there was no need to rush the review process. the draft plan was distributed by newsletter to beluga-hunting communities and tribal councils. meetings were held to discuss the plan and propose revisions. in november 1995, five years after the draft plan was adopted, the abwc unanimously adopted a revised alaska beluga whale management plan. during the next two years, tribal entities from 27 beluga hunting communities ratified the plan. twenty years later, the abwc asked the original signatory communities to reconfirm their support of the plan. since 2016, 23 communities have passed new resolutions of support, and eight new communities have ratified the plan (available online at http://www.north-slope.org/departments/wildlife-management/co-management-organizations/alaska-beluga-whale-committee). co-management agreement at the abwc’s first meeting in 1988, a regional delegate recommended that at some time in the future, a cooperative agreement (i.e., co-management agreement) was needed between the agencies and the users for managing belugas. at that time, the only cooperative agreement between users and the federal government was for bowhead whales. shortly after the mmpa was amended to allow anos to enter into cooperative agreements for the co-management of subsistence use, the abwc began to formally discuss a co-management agreement between the abwc and the nmfs. the abwc was envisioned as the umbrella organization concerned with statewide, national and international affairs. regional groups would later develop local management plans, hunting guidelines and means of enforcement. the development of the abwc co-management plan began in 1994 and continued over the next six years. there were no beluga management or conservation ‘crises’ at the time, so planning did not need to respond to an external time line. the abwc distributed questionnaires and held co-management workshops to address questions about the role of the abwc as a statewide organization, the role of regional and local groups and plans, coordination among villages, and how the abwc should deal with research, allocation, regulation and enforcement. early participants agreed that an abwc co-management plan would include bristol bay, yukon/kuskokwim, norton sound, chukchi sea (including kotzebue sound) and the beaufort sea. in 1997, abwc legal counsel developed a draft agreement between the abwc and the nmfs that was reviewed and modified by the abwc executive committee and distributed to all members with suggestions about how to encourage discussions in their communities. subsequently, drafts were distributed and discussed at multiple abwc meetings and a special abwc science workshop. a newsletter including the draft agreement and a plain english version explaining what the legal text meant was mailed to over 2000 beluga hunters. while the abwc and its member communities reviewed the draft, the nmfs conducted an in-house review and then met with the abwc executive committee to finalize the agreement. the abwc executive committee and abwc delegates signed the final agreement between the national marine fisheries service and the alaska beluga whale committee for co-management of the western alaska beluga whale population at the 1999 abwc meeting, and the nmfs was signed in december 1999. by november 2000, 22 villages had ratified the agreement, and an additional 10 have ratified it since then. regional plans the abwc’s co-management agreement with the nmfs specifies that “each management region within the abwc shall have responsibility for preparing, in consultation with the abwc, a regional management plan for the management of the beluga whale subsistence hunt within that region.” regional plans can provide more detail about hunting guidelines than the quite general abwc management plan and the cooperative agreement with the nmfs and can accommodate regional differences in hunting methods and approaches to management. funding and time constraints preclude conducting planning activities for all stocks at once, so the abwc has prioritized two areas it considers of greatest concern: kotzebue sound and the ebs. abwc hunter-delegates have been supportive of regional planning efforts, cautioning that it is necessary to proceed slowly, with adequate consultation along the way. they remind the abwc that many hunters in the villages have less exposure to ideas about management planning and may be hesitant to move forward with a formal plan until they learn more about it and why it is needed. some of the reluctance may result from fear that such a plan would reduce management flexibility (fernandez-gimenez et al. 2008). developing and writing down specific guidance could also lead to the perception of increased enforcement. when abwc delegates and hunters were interviewed in 2002, they favoured an educational approach that would include information about belugas as well as proper hunting practices, safety and traditional values. the erosion of respect for elders, community, tradition and the animals themselves was a major concern (fernandez-gimenez et al. 2008). at the abwc meetings and planned workshops, participants regularly cite the lack of respect for elders, who are often the ones involved in developing plans, as one of the greatest impediments to the acceptance and implementation of planning efforts. more education and improved communication with communities and especially with young hunters are considered essential to any planning effort. kotzebue sound. belugas were once abundant in kotzebue sound (lowry et al. 2020). they became less abundant beginning in the 1960s and 1970s. hunters observed that they became less common near kotzebue when jet planes began to land there in the early 1980s. until the 1970s and early 1980s, they were regularly harvested by the communities of kotzebue, noatak and kivalina in northern kotzebue sound and by buckland and to a lesser degree deering in eschscholtz bay to the south. as belugas became less abundant and hunting became more difficult in the northern sound, many kotzebue hunters began to harvest belugas in southern kotzebue sound and eschscholtz bay. in 1983, after multiple years of high harvests by hunters from all over the sound (up to 130 per year), the number of belugas using eschscholtz bay declined precipitously, and the hunt was no longer feasible. this decline also roughly coincided with a large entrapment of belugas in the soviet far east in late 1984, but the stock identity of those animals was never determined (ivashin & shevlyagin 1987). there are no reliable pre-decline abundance estimates of kotzebue sound belugas. since 1983, belugas have occurred in such low numbers that conventional abundance surveys are impractical. genetics information indicates that belugas harvested there in the 1980s, prior to the collapse of the hunt, constituted a separate stock (o’corry-crowe et al. 2018; o’corry-crowe et al. 2021 [this special cluster]). the stock identity of belugas currently using kotzebue sound is unclear since few samples are available (o’corry-crowe et al. 2021). thirty to forty years ago we saw things happening to belugas but we didn’t really notice them. we had the opportunity in the past to do things differently but we didn’t … now we are working on it. the beluga plan is important. the hunters have to leave belugas alone for a while so they can come back. it is important to save them so they will be here for the grandchildren in the future. (tribal elder, native village of buckland) elders and beluga hunters began meeting in 2015 to discuss what can be done to help kotzebue sound belugas recover to their former abundance. the native village of buckland obtained grant funding for a buckland beluga project to examine both traditional knowledge and science to develop a beluga plan. the abwc became a partner in the kotzebue sound planning process in 2016 and has supported meetings and newsletters since the buckland beluga project ended. the first kotzebue sound beluga management plan was drafted by elder hunters, with input from scientists, at a workshop in 2016. that plan was reviewed and revised at subsequent community outreach meetings and at regional meetings and workshops. draft and final plans were distributed by newsletter. the plan includes hunter guidelines about when not to hunt, safe zones, not hunting females with calves, no netting (because it disproportionately catches females with young), minimizing loss, and sections on traditional knowledge, science, communication and education. the kotzebue sound beluga plan has been ratified by tribal councils of four of the five affected communities (a near-final copy of the plan in newsletter form is available on the abwc website). implementation of the plan, despite the care with which it was developed, is problematic. local hunters and subsistence leaders are faced with a dilemma: they know there are not many belugas left in kotzebue sound, and they know it is necessary to agree to limit hunting to foster recovery. at the same time, hunters, their families and communities long for beluga meat and muktuk (skin and blubber) on their tables. throughout the management planning process, meetings and workshops were well-attended by elder hunters who worked hard to develop solid ideas about restoring belugas to kotzebue sound. however, young, active hunters generally did not participate. in 2018, the summer after the draft management plan was approved by the planning team and distributed by newsletter, the kotzebue sound beluga harvest was the highest it had been since 2011. the situation is discouraging to all concerned. belugas reproduce slowly. even if all hunting stopped tomorrow, it could be decades before there are enough belugas to support a sustainable harvest in kotzebue sound. for older hunters, this could mean they would never again participate in harvesting belugas, once a mainstay of their traditional subsistence lifestyle. there has been no hunting of a similarly depleted beluga stock in cook inlet since 1999, and it has still not begun to recover (shelden & wade 2019). the kotzebue sound situation is compounded by uncertainty about whether the remaining ‘kotzebue sound belugas’ are part of the original kotzebue sound stock (see o’corry-crowe et al. 2021) or are intermittent migrants from other stocks, particularly the beaufort sea stock. compliance with the kotzebue sound tribal beluga management plan is voluntarily. while the mmpa allows for the development of federal regulations to limit harvest, this can only occur if a stock is designated as depleted. although the historical stock of kotzebue sound belugas is greatly reduced, ambiguity about the stock identity of remnant belugas has resulted in no such designation. thus, there is no ‘weight of law’ behind the plan. hunters do not want federal regulation or for the government to get involved in local beluga management, but without it, the process appears to be at a standstill. elder hunters on the kotzebue sound beluga planning team express their concerns in these words: (we need) a regional plan, stating that our people have to work together. some of the young people have lost respect for the elders. we need to have strong hunt leaders again. a solution has to be built on cooperation, with everybody helping each other as we used to do. the region could work together to address the issue as a tribally led solution, rather than relying on the federal regulators to do it. we don’t talk, we don’t work it out, but we need to. if we don’t cut back there will be no belugas in the future. imagine no more belugas. if we don’t act now, this is coming. we need to cut back on hunting so belugas can come back…. ebs. before the abwc’s co-management agreement specified that the abwc would develop regional management plans, three villages in norton sound developed a beluga plan for norton bay. the elim-shaktoolik-koyuk hunter bylaws were adopted in 1994. for the next 20 years, in large part, because the ebs beluga stock was considered healthy and without significant management issues, there was no effort to develop a broader regional ebs plan. this changed as abwc members realized how difficult it is to recover depleted beluga stocks and to implement remedial plans in times of duress. in alaska, the cook inlet stock (listed as endangered under the endangered species act in 2008) and that of kotzebue sound stand as examples of situations gone bad. actions were not taken soon enough to curtail the harvest as beluga populations declined, and developing remedial actions was contentious and/or ineffective. abwc delegates have learned the details of these difficulties at abwc meetings and have made a concerted decision to try to avoid this situation for other currently healthy stocks. belugas from the ebs stock, unlike kotzebue sound, are abundant, with a recent population estimate of 9242 (ferguson et al. 2018; lowry et al. 2020). a 2% harvest level (wade 1998) would be 185. the retrieved harvest for 21 ebs villages for the 13 years spanning 2007–2019 averaged 194 belugas annually (range 174–236) or 2.05% (table 1). it is timely that ebs hunters are beginning to discuss how to keep harvests at a sustainable level. however, this discussion is complicated by the number of villages involved (>20) and because two culturally and socially distinct regions (norton sound and yukon delta) harvest from the ebs stock. without facilitation by the abwc, it is unlikely that communities would address this issue, or that norton sound and yukon delta communities would interact about a beluga plan. in fact, when an ebs plan was first discussed, the hunters initially proposed having two separate plans. abwc members are committed to proactively developing an ebs management plan while the stock is healthy and the harvest sustainable. the abwc has initiated the process by holding ebs workshops in conjunction with its last two annual meetings and distributing a newsletter to ebs hunters describing abundance, harvest information and the need for management planning. meetings, with presentations by both abwc officers and scientists, are scheduled to occur in major beluga hunting villages in the near future. the intent is to initiate widespread discussions in the ebs region, provide many opportunities for hunter and community input and, when there is general acceptance, to put a plan in place that will prevent future problems. about 50% of abwc delegates from the ebs are young active hunters who encourage and support a planning process, unlike kotzebue sound, where active young hunters did not participate. too often plans are precipitated by crisis, and ‘crisis management’ is rarely smooth or effective. through proactive discussions, education and planning the abwc hopes to ensure the beluga harvest in the ebs remains sustainable and to avoid a management problem.’ the following statements from hunters reflect this concern: with the ebs beluga stock recently counted we need to manage it to the best of our ability. filling our freezers is important but not at the risk of over-harvesting the population. the yearly take of belugas today is nearing our harvestable surplus. it is up to us as hunters to manage our beluga resource responsibly so we can pass this hunting tradition on to our children and grandchildren. kotzebue sound and anchorage belugas are in big trouble. we don’t want to end up like that. (tom gray, abwc chairman and nome beluga subsistence netter) we want a beluga plan so belugas will be here for our kids. (albert simon, abwc vice chairman and beluga subsistence hunter) the plan must come from our people. (marvin okitkun, abwc member-at-large and beluga subsistence hunter) capacity building and succession planning meaningful co-management depends on commitment to common goals, but it is also hugely dependent on individuals, personalities and working relationships. the abwc has relied on a core of key individuals who have been part of the abwc for decades to conduct the committee’s work. because the abwc does not hire an executive director, several executive committee members and delegates have accepted responsibility for tasks such as organizing and holding meetings, facilitating the collection of harvest data, drafting management plans and newsletters, implementing research plans, drafting and submitting funding requests and managing awards. the abwc has been fortunate that its agency members (nsb, adfg and nmfs) have assisted with the organization of annual meetings, transport and archival of samples and applying for and receiving additional funding for research. additionally, the nsb has assisted the abwc by submitting proposals, managing grant funds and helping to coordinate research. in the not-too-distant future, the abwc leadership—hunters, managers and scientists—is likely to change. key individuals will retire or step down, and replacements with similar commitment to the abwc’s mission and the time to commit will have to be found. there is a need to train and prepare for that transition. in theory, capacity-building is a straightforward concept. in reality, it is more difficult to implement. government agencies and universities fund full-time positions to conduct research and management activities. scientific personnel receive salaries. in contrast, hunters participate in both research and management activities mostly on their own time. their ‘payment’ for attending meetings and serving as officers is reimbursement for travel and per diem. in the best of circumstances, they may be paid a daily stipend for participation and the use of their boats or reimbursement for collecting samples. consequently, many, if not most, participants are elder hunters who are retired and no longer have young growing families to feed. collectively, the abwc recognizes the need to bring in young people—both scientists and hunters. they will be the ones who must implement management plans and abide by decisions about harvesting and who will be the future leaders. however, young staff and young delegates or research participants require predictable funding, someone to pay their salaries, and some assurance that there will be work for them in years to come. each year, some of the abwc’s younger delegates cannot attend meetings because they cannot get away from their jobs or family responsibilities. an ebs tagger-training programme did not take place in two consecutive years because salmon fishing was poor and participants needed to work fighting fires to support their families. in 2019, 30% of the abwc delegates, and 50% of those from the ebs, were younger than 40. these young hunters invigorated discussions and contributed new ideas, but the time they have available for abwc activities is limited by the practicalities of earning a living. the capacity needs of communities extend from bureaucratic aspects of managing grants to conducting research. capacity-building must match not only the needs of agency managers and the scientific community but must be compatible with local needs, practices, capacity limitations and interests of beluga hunting communities. for example, the conduct of aerial surveys is not research, in which abwc delegates generally want to participate or build capacity. it is attractive to only a few professional career biologists and is becoming less so as new, safer, technology-intensive methods become available. it is not surprising that hunters accustomed to being outside and on the water do not want to spend 1–2 weeks of long days confined in a small aircraft surveying mostly empty water. furthermore, surveys often take place during commercial fishing season, when people are busy with fishing and other seasonal economic activities. although they do not want to participate, hunter-delegates are nonetheless strongly supportive of beluga aerial surveys. in contrast, participation in satellite tagging hunter-tagger programmes is a form of capacity building that is a ‘good match.’ catching and tagging belugas utilizes the skills and equipment beluga hunters have acquired through their daily lives and activities. the timing is flexible and does not require large blocks of time that preclude seasonal subsistence or other economic activities. communication communication among scientists, beluga hunters, beluga hunting communities and managing agencies is essential for successful co-management. even though this is an obvious statement, communication can be challenging in a group with broad representation, which includes elders who may not use e-mail or social media, scientists who have been trained to speak technically and often do not have skills or experience necessary to use plain language, individuals with cultural differences (e.g., yupik, inupiat and western) and those with diverse backgrounds in education and experience. a foundation of the abwc’s success has been effective communication among its members. at abwc meetings, scientists provide up-to-date information about belugas. since the first meetings, they have been required to speak in jargon-free english and to explain scientific terms. one effective technique at abwc meetings has been to do ‘roundtables’ at the end of meeting sessions, in which each delegate comments on the subjects under discussion. this ensures that less outspoken members have an opportunity to provide input. the abwc’s communication about genetics and stock structure is a good example of how it has fostered communication between hunters and scientists. in an iterative process, hunter delegates worked closely with scientists to help them develop reports and graphics that were readily understood (see fig. 2). as a result, an active dialogue developed about concepts of stock identification. the result was an outpouring of samples that continues today and broad appreciation about the need for information about stock identity. a previous abwc chairman, ross schaefer, pointed out that “o’corry-crowe’s presentation was a perfect example of what the abwc had done together. every single person in the room had contributed and the study utilized all information from all people.” fig. 2 presented at an early abwc meeting, this infographic shows how knowledge of genetic hapolotype frequencies can be used to define beluga stocks and is a good example of an effective tool of communication between scientists and non-scientists. (courtesy of greg o’corry-crowe, florida atlantic university.) the removal of the ‘scientific language barrier’ results in extensive questioning of speakers at abwc meetings and workshops. because scientists are required to talk in plain english and because abwc delegates are accustomed to and at ease communicating with scientists, abwc delegates provide significant input into the design and interpretation of studies. when everyone understands a project, everyone can contribute to making a better, more logistically feasible project with results that are broadly accepted. reports by hunters at annual meetings, and interchange among hunter-delegates and other abwc members allow managers and scientists to better understand the environmental conditions in western and northern alaska, provide observations about possible changes in beluga behaviour and habitat use, and raise concerns related to climate change, oil and gas activities, or other human activities. this, in turn, may provide the foundation for future research proposals to better understand these things. the abwc and its scientists have published more than 40 articles in the peer-reviewed literature since 1993, and more than 20 since 2015 (http://www.north-slope.org/departments/wildlife-management/co-management-organizations/alaska-beluga-whale-committee/abwc-publications). these publications have reported on work conducted with the involvement and support of beluga hunters throughout the abwc regions. genetics publications reported findings from samples collected almost entirely by hunters. similarly, publications about diet, health and contaminants were based largely on hunter-provided samples. satellite-tagging studies relied on community support, hunter participation and hunter tagging to catch as well as tag belugas. acoustics studies and aerial surveys were prioritized by abwc members and supported by abwc co-management funding. these publications are directed at a scientific audience, but plain-english summaries are included in the abwc’s meeting packet for delegates to read and take home to their communities. residents of small rural communities in coastal alaska experience meeting fatigue because so many agencies and projects hold meetings to report their findings or solicit opinions. to avoid ‘yet one more meeting,’ and in an attempt to reach a broad cross-section of coastal residents, the abwc has distributed 15 plain-english printed newsletters since 1991. the newsletters have facilitated development of the abwc–nmfs co-management plan and, more recently, the kotzebue sound and ebs beluga plans. special newsletters dealt in-depth with issues such as kotzebue sound belugas and how genetics is used to study beluga stocks. abwc hunter-delegates have repeatedly emphasized newsletters as a good way to reach a diverse audience of both elders and youth. the abwc has a facebook page where it can communicate information directly to the hunters, and where hunters from around alaska can communicate directly about belugas, but most delegates still consider newsletters more broadly useful than social media. the abwc has held five science workshops to address broad, and often international, aspects of beluga biology and management. the workshops have allowed time for more in-depth discussions of topics and facilitated information exchange and cooperation between alaskans and participants from elsewhere, especially canada. more recently, the abwc held two women’s beluga workshops in conjunction with annual abwc meetings. in prior years, it was apparent that some abwc delegates were accompanied to meetings by their wives, and that some of them attended all or part of the abwc meetings. when approached, they were enthusiastic about attending a women’s beluga workshop and meeting other women interested in belugas and beluga hunting and were active participants when the workshops occurred. participants shared information about processing and sharing belugas; using, preparing and storing belugas; and medicinal uses. communication remains a challenge. as in society in general, people are deluged with information, and many entities compete for their attention. the abwc continues to seek better ways to communicate information and involve more people in beluga research and management. differences between the abwc and other co-management groups the marine mammal co-management anos in alaska are numerous. there is approximately one co-management organization per marine mammal species used for subsistence, with the exception of four ice seal species, which are all included under the ice seal committee. the other arctic anos include the abwc, the alaska eskimo whaling commission, the eskimo walrus commission and the alaska nannut co-management council. there are other marine mammal co-management organizations in southern alaska. they were all created under the mmpa and receive funding from either the nmfs (whales and seals) or the us fish and wildlife service (walruses and polar bears). the alaska eskimo whaling commission, the eskimo walrus commission, and the alaska nannut co-management council each request and receive annual funding (from the nmfs, the fish and wildlife service or other organizations) for an executive director and sometimes support staff for the operation of the organization. the alaska eskimo whaling commission and the alaska nannut co-management council also receive funds for legal counsel. the nsb provides a varied amount of scientific support for each of the organizations, as do the adfg, the nmfs and the fish and wildlife service (dependent on the species). the abwc and the ice seal committee receive bureaucratic support (e.g., grant administration, travel) from the nsb. the abwc membership structure is unique among marine mammal co-management organizations in alaska. the delegates/commissioners for all other anos include only alaska native hunters or their regional representatives. some may have scientists, legal counsel and other support staff, but agency managers and scientists serve as advisors or partners and not members. the abwc is the only marine mammal ano that includes agency managers and scientists as voting members. the abwc is more similar to the co-management boards in canada than to other alaska anos. in canada, land claim agreements created co-management boards. under the land claim agreements, the federal government provides regular funding to the inuvialuit, the nunavut and the nunavik for the management of belugas and other subsistence species. with federal funding, each region created hunters, fishers and trappers associations that, in turn, appoint members to a regional organization (e.g., the inuvialuit game council). the regional organization, in turn, appoints members to co-management boards that also have appointees from the federal government and, in many cases, the relevant provincial or territorial government. one of the main objectives of those organizations is to provide inuit with a greater role in making management decisions about the resources that are critical for helping to meet nutritional and cultural needs. the co-management boards have had variable success at meeting that objective. the abwc is distinctive in the breadth and inclusion of its membership and its deliberations. no other group includes such broad community representation combined with members from government agencies. some observers, and indeed some participants, view this feature as a drawback because they believe it dilutes the role of alaska native tribes. for others, the broad and inclusive representation means that the abwc’s decisions are binding not only on the alaska native representatives but also on the government agencies, thus elevating the abwc above the level of an advocacy group. discussion the goal of co-management is to achieve sound resource conservation through an equal partnership between hunters and tribal representatives on one hand and government managers and scientists on the other hand. many inuit in alaska and canada are distrustful of federal governments for many reasons but are also hopeful that co-management will provide a more equal footing (tyrrell 2008). many factors can promote or inhibit such a partnership, ranging from the quality of personal relationships (huntington 2011) to the structure of the organization. co-management is hindered by poor communication, lack of a common system of belief (e.g., similar management goals), the undermining of inuit systems of management, insufficient funding, insufficient sharing of power and decision-making and, in some cases, complex administrative structures (gombay 2019). co-management was a nascent idea when the abwc was formed. there were no real examples of what co-management should—or could—be. over the course of 30 years, the abwc has developed its own model for what it thinks co-management is—a true partnership between beluga subsistence hunters, managing agencies and scientists. long-standing participation of members has been fundamental to the abwc’s success. it has facilitated communication and cooperation, improved the outcome of research projects and increased the acceptance of results. through this structure, research and management priorities have been discussed freely, disagreements stated and solutions developed in a non-antagonistic forum. the inclusion of scientists and hunters together in the abwc did not guarantee success. as toomey (2016) noted, working with indigenous people in bolivia, “in such spaces of encounter or misencounter between scientists and local people, knowledge can be exchanged or hidden away, worldviews can be expanded or further entrenched, and scientific research can be welcomed or rejected.” fernandez-gimenez et al. (2006: 7) summarized the abwc’s success as growing from lengthy relationships between hunters and scientists who were established in a “variety of different settings for interaction and an organizational culture that allowed for candid exchanges in a mutually respectful environment” that nurtured the exchange of ideas and knowledge and allowed for “challenges to each other’s beliefs and world views.” involvement of hunters in abwc research and research decisions has fostered social interactions and situations that build trust, mutual understanding and novel ecological insights (huntington 2011). when complementary threads of knowledge weave together, innovation and new insights may follow (huntington et al. 2004; david-chavez 2019). this research model produces results that are scientifically valid and locally accepted. because hunters as well as scientists are involved in the design, conduct and interpretation of studies, the results and conclusions become ‘ours’ not ‘theirs.’ it is critical that hunters be integrally involved in managing their subsistence resources. hunting is more than harvesting. for many indigenous people, it is about being connected to the environment, spending time together and teaching youth and is integral to cultural continuity and identity. hunting elevates their spirits, grounds them or makes them feel whole (inuit circumpolar council alaska 2020). the failure of beluga conservation in cook inlet and kotzebue sound threatens this crucial aspect of indigenous culture and well-being and has strongly motivated the abwc to prioritize regional management planning. planning is, however, a complicated process that entails more than abwc delegates conceiving and adopting a plan: official approval by a leadership council will not ensure local support (toomey 2016). people at many levels must ‘buy in’ to implement the plan and to change their own behaviour. cultural reluctance to tell others what to do, generational gaps in communication and the absence of an external motivator (such as legal mandates) make voluntary self-management difficult. whether kotzebue sound beluga hunters and the abwc can navigate these difficulties to implement the kotzebue sound beluga plan and start the long recovery process for kotzebue sound belugas is not yet determined. in the ebs, the relatively high abundance of belugas and their occurrence in pods or large groups when they are encountered bring other management challenges: even as the harvest is approaching the calculated sustainable level, the hunters do not perceive a decline. the importance of implementing proactive measures is not clear to everyone. to be successful, regional management plans must be developed locally. when the abwc engages villages in management planning, it must communicate that the plan is a hunter-generated plan, not a government plan. it must explain why a plan is a good idea and convince communities to join in. many attempts to engage indigenous communities in resource management require the villagers to fit their knowledge and customs into western moulds, which is hampered by fundamental philosophical and practical differences (gadamus & raymond-yakoubian 2015). regional plans are further complicated because hunting guidelines are traditionally enforced within communities, not across broad areas (fernandez-gimenez et al. 2008), and the transition from local norm-based systems to a more formal regional plan will almost certainly be difficult. although it is treading new ground, the abwc hopes it can develop regional plans that are culturally appropriate and can influence hunter behaviour and promote sustainability of the beluga harvest at a time when the human population is growing, and environmental conditions for belugas are changing. the abwc approach of combining alaska native values of respectful human and animal relationships and community traditions with scientific knowledge will hopefully result in a long-term sustainable harvest. as expressed by a previous abwc chairman, roswell schaeffer, of kotzebue: today i am very proud to say that abwc is truly co-management at its best. those who attend our meetings are sober, very active in our discussions, and instrumental in our decision-making about issues, policies and research. the positive energy is infectious. our meetings reflect this sense of working together with the same spiritual energy, like a whaling crew and its people pulling up a huge bowhead whale. it takes this kind of positive energy and commitment to our work to preserve the rights of our people to continue to harvest the belugas and to also make sure we have these beautiful creatures for those to come in the future. i applaud all our members who contribute in every meeting. consistent funding has contributed greatly to the abwc’s success. federal funding has supported annual meetings, science workshops, newsletters, management planning, collection of harvest data and a variety of management-related research projects. the abwc has leveraged those funds with in-kind contributions of research equipment, logistical support and laboratory analysis from adfg, the nmfs, the nsb, alaska native tribes and other native organizations, and the many individuals associated with the abwc who have volunteered their time as well as grant funds from other funding organizations. the implementation of the nmfs ano co-management funding program in 2011 fundamentally altered the co-management relationship between the abwc and the nmfs. until then, funding decisions were collaborative and responsive to abwc priorities. now, a review panel makes decisions about project priorities, allocation among projects and funding reductions across ano proposals. there is no opportunity for input from co-management organizations. a better approach would be for the nmfs to set aside specific funds to support co-management of belugas annually and then to work with the abwc to develop priorities and a spending plan together. conclusions the abwc has succeeded because it has dared to be different. members are proud of how they work together. other anos have sometimes disapproved of the abwc’s inclusion of non-native scientists and agency managers as members. agency personnel are sometimes uncertain about how they ‘fit.’ but the abwc considers this as its greatest strength. the knowledge of hunters and scientists has not been put into separate bins, but instead combined, drawing from each to get the project or the job done in the best possible way. the abwc has not focused on theoretical concepts of what co-management should be, but on what works—and what does not. members discuss difficult subjects openly at the meeting table, not only with like-minded colleagues in private conversations. none of the abwc progress would have happened without the first meeting when the group had to choose a model for its organization. there were some wise people at that meeting who understood that direct contact between hunters and researchers was essential. under the abwc model, the committee sets the priorities and these priorities are then adopted by nmfs and adfg. with an annual budget of $200,000, it wouldn’t be possible to accomplish all the abwc does without bringing nmfs, adfg and others to the table to help and contribute to its efforts. because everyone works together, there is huge support for abwc programs and everyone follows up on their commitments. the hunters and researchers are in handshake reach. through the abwc format, the federal government is accountable to its citizens, the beluga hunters. through the abwc, everyone speaks out and shares opinions and knowledge. the abwc has the government’s blessing. it has a management plan and a research plan. it doesn’t need outside regulation because regulation comes from inside. (marie adams carroll, an abwc founding member) acknowledgements many individuals and organizations contributed to the success of the abwc; only some of them have been mentioned here. the authors thank the various mayors of the nsb, directors of the nsb department of wildlife management and grant administrators from the nsb grants division for their support. shawn carey and jenn hall-brown provided many years of grant administration from the nmfs. doug demaster, former director, nmfs alaska fisheries science center, has been particularly supportive and helpful. demaster and john citta provided helpful comments on this manuscript. finally, the authors also thank lloyd lowry (deceased), who was instrumental in the creation of the abwc and contributed to the organization in many ways over many years. references adams m., frost k.j. & harwood l.a. 1993. alaska and inuvialuit beluga whale committee (aibwc)—an initiative in “at home management”. arctic 46, 134–137. allen b.m. & angliss r.p. 2015. alaska marine mammal stock assessments, 2014. noaa technical memorandum nmfsafsc-301. seattle, wa: alaska fisheries science center, national marine fisheries service national oceanic and atmospheric administration, us department of commerce. citta j.j., frost k.j. & quakenbush l. 2020. aerial surveys of bristol bay beluga whales in 2016. marine fisheries review 81, 98–104, doi: 10.7755/mfr.81.3–4.5. citta j.j., o’corry-crowe g., quakenbush l.t., bryan a.l., ferrer t., hobbs r.c. & olsen m.j. 2018. assessing the abundance of bristol bay beluga with genetic mark–recapture methods. marine mammal science 34, 666–686, doi: 10.1111/mms.12472. citta j.j., quakenbush l.t., frost k.j. & lowry l., hobbs r.c. & aderman h. 2016. movements of beluga whales (delphinapterus leucas) in bristol bay, alaska. marine mammal science 32, 1272–1298, doi: 10.1111/mms.12337. cruikshank j. 1998. the social life of stories: narrative and knowledge in the yukon territory. lincoln, ne: university of nebraska press. david-chavez d.m. 2019. a guiding model for decolonizing environmental science research and restoring relational accountability with indigenous communities. phd dissertation, colorado state university. ferguson m., frost k., brower a., wil-loughby a., sims c. & suydam r. 2018. esti-mated abundance and distribution of eastern bering sea belugas from aerial surveys in 2017. in j. lee & v. helker (eds.): 2018 alaska marine science symposium. january 22–26, 2018. hotel captain cook & egan center, an-chorage, alaska. pp. 207–208. anchorage, ak: alaska marine science symposium. fernandez-gimenez m.e., hays j.u. jr., huntington h.p., andrew r. & goodwin w. 2008. ambivalence toward formalizing customary resource management norms among alaska native beluga whale hunters and tohono o’odham livestock owners. human organization 67, 137–150, doi: 10.17730/humo.67.2.008083027273n05q. fernandez-gimenez m.e., huntington h.p. & frost k.j. 2006. integration or cooptation? traditional knowledge and science in the alaska beluga whale committee. environmental conservation 33, 306–315, doi: 10.1017/s0376892906003420. frost k.j. & suydam r.s. 2010. subsistence harvest of beluga or white whales (delphinapterus leucas) in northern and western alaska 1987 to 2006. journal of cetacean research and management 11, 293–299. gadamus l. & raymond-yakoubian j. 2015. a bering strait indigenous framework for resource management: respectful seal and walrus hunting. arctic anthropology 52, 87–101. gambell r. 1993. international management of whales and whaling: an historical review of the regulation of commercial and aboriginal subsistence whaling. arctic 46, 97–107. givens g.h., ferguson m.c., clarke j.t., willoughby a., brower a. & suydam r. 2020. abundance of the eastern chukchi sea stock of beluga whales, 2012–2017. arctic 73, 485–498, doi: 10.14430/arctic71592. gombay n. 2019. ‘there’s no one way of doing things’: wildlife management and environmentality in nunavik. hunter gatherer research 3, 651–675, doi: 10.3828/hgr.2017.33. harwood l.a., innes s., norton p. & kingsley m.c.s. 1996. distribution and abundance of beluga whales in the mackenzie estuary, southeast beaufort sea, and west amundsen gulf during late july 1992. canadian journal fisheries aquatic sciences 53, 2262–2273, doi: 10.1139/f96–180. hazard k. 1988. beluga whale—delphinapterus leucas. in j.w. lentfer (ed.): selected marine mammals of alaska: species accounts with research and management recommendations. pp 198–235. washington, dc: marine mammal commission. huntington h.p. 2011. the local perspective. nature 478, 182–183, doi: 10.1038/478182a. huntington  h.p., danielson s.l., wiese f.k., baker m., boveng p., citta j.j., de robertis a., dickson d.m.s., farley e., george j.c., iken k., kimmel d.g., kuletz k., ladd c., levine r., quakenbush l., stabeno p., stafford k.m., stockwelld. & wilson c. 2020. evidence suggests potential transformation of the pacific arctic ecosystem is underway. nature climate change 10, 342–348, doi: 10.1038/s41558-020-0695-2. huntington h.p., suydam r.s. & rosenberg d.h. 2004. traditional knowledge and satellite tracking as complementary approaches to ecological understanding environmental conservation. environmental conservation 31, 177–180, doi: 10.1017/s0376892904001559. inuit circumpolar council alaska 2020. food sovereignty and self-governance: inuit role in managing arctic marine resources. anchorage, ak: inuit circumpolar council alaska. ivashin m.v. & shevlyagin k.v. 1987. the white whale (delphinapterus leucas pallas, 1776): entrapment and escape in the ice of senjavin strait, u.s.s.r. reports of the international whaling commission 37, 357–359. lowry l.f., citta j.j., o’corry-crowe g., quakenbush l., frost k.j., suydam r., hobbs r.c. & gray t. 2020. distribution, abundance, harvest and status of western alaska beluga, delphinapterus leucas, whale stocks. marine fisheries review 81, 54–71, doi: 10.7755/mfr.81.3–4.2. lowry l.f., frost k.j., zerbini a., demaster d. & reeves r.r. 2008. trend in aerial counts of beluga or white whales (delphinapterus leucas) in bristol bay, alaska, 1993–2005. journal of cetacean research management 10, 201–207. lowry l.f., kingsley m.c.s., hauser d.d.w., clarke j. & suydam r. 2017. aerial survey estimates of abundance of the eastern chukchi sea stock of beluga whales (delphinapterus leucas) in 2012. arctic 70, 273–286. doi: 10.14430/arctic4667. lowry l.f., zerbini a., frost k.j., de master d.p. & hobbs r.c. 2017. development of an abundance estimate for the eastern bering sea stock of beluga whales (delphinapterus leucas). journal cetacean research management 16, 39–47. meek c. 2009. comparing marine mammal co-management regimes in alaska: three aspects of institutional performance. phd dissertation, university of alaska fairbanks. metcalf v. & robards m. 2008. sustaining a healthy human–walrus relationship in a dynamic environment: challenges for co-management. ecological applications 18 suppl., s148–s156, doi: 10.1890/06-0642.1. nadasdy p. 2003. reevaluating the co-management success story. arctic 56, 367–380, doi: 10.14430/arctic634. o’corry-crowe g., dizon a.e., suydam r.s. & lowry l.f. 2002. molecular genetic studies of population structure and movement patterns in a migratory species: the beluga whale (delphinapterus leucas) in the western nearctic. in c.j. pfeiffer (ed.): molecular and cell biology of marine mammals. pp. 53–64. melbourne, fl: krieger press. o’corry-crowe g., ferrer t., citta j.j., suydam r., quakenbush l., burns j.j., monroy j., whiting a., seaman g., goodwin w., meyer m., rodgers s. & frost k.j. 2021. genetic history and stock identity of beluga whales in kotzebue sound. polar research 40, article no. 7623, doi: 10.33265/polar.v40.7623. o’corry-crowe g., mahoney a.r., suydam r., quakenbush l., whiting a., lowry l. & harwood l. 2016 genetic profiling links changing sea-ice to shifting beluga whale migration patterns. biology letters 12, article no. 20160404, doi: 10.1098/rsbl.2016.0404. o’corry-crowe g., suydam r., quakenbush l., potgieter b., harwood l., litovka d., ferrer t., citta j., burkanov v., frost k. & mahoney b. 2018. migratory culture, population structure and stock identity in north pacific beluga whales (delphinapterus leucas). plos one 13, e0194201, doi: 10.1371/journal.pone.0194-201. o’corry-crowe g., suydam r., quakenbush l., smith t.g., st. aubin d., lydersen c., kovacs k.m., orr j., harwood l., litovka d. & ferrer t. 2020. group structure and kinship in beluga whale societies. nature scientific reports 10, article no. 11462, doi: 10.1038/s41598-020-67314-w. o’corry-crowe g.m., suydam r.s., rosenberg a., frost k.j. & dizon a.e. 1997. phylogeography, population structure, and dispersal patterns of the beluga whale, delphinapterus leucas, in the western nearctic revealed by mitochondrial dna. molecular ecology 6, 955–970, doi: 10.1046/j.1365-294x.1997.00267.x. pinkerton e.w. (ed.) 1989. co-operative management of local fisheries: new directions for improved management and community development. vancouver: university of british columbia press. robards m.d, burns j.j., meek c.l. & watson a. 2009. limitations of an optimum sustainable population or potential biological removal approach for conserving marine mammals: pacific walrus case study. journal of environmental management 91, 57–66, doi: 10.1016/j.jenvman.2009.08.016. shelden k.e.w. & wade p.r. (eds.) 2019. aerial surveys, distribution, abundance, and trend of belugas (delphinapterus leucas) in cook inlet, alaska, june 2018. afsc processed report 2019-09. seattle, wa: alaska fisheries science center, national marine fisheries service national oceanic and atmospheric administration, us department of commerce. singleton s. 1998. constructing cooperation: the evolution of institutions of comanagement. ann arbor, mi: university of michigan press. stroeve j. & notz d. 2018. changing state of arctic sea ice across all seasons. environmental research letters 13, article no. 103001, doi: 10.1088/1748-9326/aade56. suydam r., lefevre j., givens g.h., george j.c., litovka d. & brower h.k. jr. 2021. conservation and management. in j.c. george & j.g.m. thewissen (eds.): the bowhead whale. pp. 607–619. cambridge, ma: academic press. suydam r.s. 2009. age, growth, reproduction, and movements of beluga whales (delphinapterus leucas) from the eastern chukchi sea. phd dissertation, school of aquatic and fishery sciences, university of washington. suydam r.s., lowry l.f., frost k.j., o’corry-crowe g.m. & pikok d. jr. 2001. satellite tracking of eastern chukchi sea beluga whales in the arctic ocean. arctic 54, 237–243. toomey a.h. 2016. what happens at the gap between knowledge and practice? spaces of encounter and misencounter between environmental scientists and local people. ecology and society 21, article no. 28, doi: 10.5751/es-08409-210228. tyrrell m. 2008. nunavik inuit perspectives on beluga whale management in the canadian arctic. human organization 67, 322–334, doi: 10.17730/humo.67.3.47826252k0623352. wade p.r. 1998. calculating limits to the allowable human caused mortality of cetaceans and pinnipeds. marine mammal science 14, 1–37, doi: 10.1111/j.1748-7692.1998.tb00688.x. doi:10.3402/polar.v35.22658 r e s e a r c h / r e v i e w a r t i c l e characterization of sea-ice kinematic in the arctic outflow region using buoy data ruibo lei,1 petra heil,2,3 jia wang,4 zhanhai zhang,1 qun li1 & na li1 1 state oceanic administration key laboratory for polar science, polar research institute of china, 451 jinqiao road, pudong, shanghai 200136, china 2 australian antarctic division, 203 channel highway, kingston, tasmania 7050, australia 3 antarctic climate and ecosystems cooperative research centre, university of tasmania, private bag 80, hobart, tasmania 7001, australia 4 national oceanic and atmospheric administration great lakes environmental research laboratory, 4840 s. state rd., ann arbor, mi 48108, usa keywords sea ice; kinematics; dipole anomaly; transpolar drift stream; arctic ocean; fram strait. correspondence ruibo lei, state oceanic administration key laboratory for polar science, polar research institute of china, 451 jinqiao road, pudong, shanghai 200136, china. e-mail: leiruibo@pric.org.cn abstract data from four ice-tethered buoys deployed in 2010 were used to investigate sea-ice motion and deformation from the central arctic to fram strait. seasonal and long-term changes in ice kinematics of the arctic outflow region were further quantified using 42 ice-tethered buoys deployed between 1979 and 2011. our results confirmed that the dynamic setting of the transpolar drift stream (tds) and fram strait shaped the motion of the sea ice. ice drift was closely aligned with surface winds, except during quiescent conditions, or during short-term reversal of the wind direction opposing the tds. meridional ice velocity south of 858n showed a distinct seasonal cycle, peaking between late autumn and early spring in agreement with the seasonality of surface winds. inertia-induced ice motion was strengthened as ice concentration decreased in summer. as ice drifted southward into the fram strait, the meridional ice speed increased dramatically, while associated zonal ice convergence dominated the ice-field deformation. the arctic atmospheric dipole anomaly (da) influenced ice drift by accelerating the meridional ice velocity. ice trajectories exhibited less meandering during the positive phase of da and vice versa. from 2005 onwards, the buoy data exhibit high arctic sea-ice outflow rates, closely related to persistent positive da anomaly. however, the long-term data from 1979 to 2011 do not show any statistically significant trend for sea-ice outflow, but exhibit high year-to-year variability, associated with the change in the polarity of da. the arctic climate system is undergoing abrupt change. arctic sea-ice extent and thickness have reduced dramatically over the past few decades, as a result of a complex interplay of dynamic and thermodynamic factors that affect atmosphere, sea ice and ocean (comiso 2012; zhang et al. 2012). september 2012 marked the record low sea-ice extent since 1979, the start of the satellite era (parkinson & comiso 2013). however, this trend did not continue into subsequent years (2013 and 2014), which showed only moderate reduction in minimum ice extent compared to the 1980�2010 average. sea ice moves in response to ocean currents, wind stress and the coriolis force, as well as the sloping sea surface and internal ice stress (tremblay & mysak 1997). sea-ice motion affects ice thickness distribution and also the energy and moisture budgets of atmosphere and ocean (heil & hibler 2002; zhang et al. 2010). reduction of arctic seaice concentration and thickness, and a shift of storm tracks towards higher latitudes over the arctic ocean, has led to accelerated arctic sea-ice drift, an increase in ice deformation, and a decrease in ice mechanical strengths (hakkinen et al. 2008; rampal et al. 2009; spreen et al. 2011; gimbert, jourdain et al. 2012; zhang et al. 2012). together, these have restructured the arctic sea ice into a younger and thinner pack. as such, the demise of arctic sea ice is in part related to the fact that arctic perennial sea-ice export through fram strait cannot be replenished within an annual cycle (nghiem et al. 2007). sea ice advects latent heat and transports freshwater, most markedly by sea-ice drifting from the arctic basin to polar research 2016. # 2016 r. lei et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 the north atlantic via fram strait (cox et al. 2010). this accounts for about 25% of total freshwater export from the arctic ocean (serreze et al. 2006). freshwater from the arctic basin may interrupt deep water formation in the north atlantic and significantly influence global thermohaline circulation (stouffer et al. 2006). hilmer & jung (2000) found that the correlation between the nao and sea-ice export through the fram strait changed from zero correlation (1958�1977) to about 0.7 (1978�1997). nao characterizes the sea-level pressure (slp) difference between the icelandic low and the azores high and can modulate the zonal wind there. it does not directly identify the strength of the arctic atmospheric circulation. analysing data from 1989 to 2009, vihma et al. (2012) found that compared with the ao and the da, the nao accounts for less of the interannual variability of sea-ice drift in the outflow region of arctic ocean. the ao can modulate the orientation of tds, and consequently the sea-ice export into fram strait (vihma et al. 2012; kwok et al. 2013). rigor et al. (2002) suggested that the thinning of arctic sea ice can be partly attributed to the trend in the ao towards the high-index polarity during the 1990s. however, the ao index became mostly neutral or even negative post-2002 (maslanik et al. 2007), suggesting a weak link between the ao and the rapid arctic sea-ice decline (wang et al. 2009). wu et al. (2006) identified an important forcing for arctic sea-ice export to be the east�west dipole pattern (i.e., da) of slp, with centres of action over the kara and laptev seas and the canadian arctic archipelago. this slp dipole produces anomalous meridional winds across fram strait (tsukernik et al. 2010). wang and co-workers (2009; 2014) suggested that recent record lows of arctic summer sea-ice extent were linked to the persistent positive polarity of the da. although they provide large-scale coverage, remote sensing data of sea-ice drift are limited by their relatively coarse spatial and temporal resolution (stern & lindsay 2009). therefore, ground data are still required to validate and to complement the satellite products. to resolve ice deformation, drifting buoy arrays are required. unfortunately, buoys deployed in the arctic outflow region typically have not been sufficiently clustered to monitor the drift of sea ice (rampal et al. 2008). here, we derive the spatial and temporal variability of ice kinematics in the arctic outflow region using a total data set of 42 ice-tethered buoys (fig. 1). this includes a three-buoy array deployed in august 2010 by the chinese national arctic research expedition (identified as buoys a�c), one ice mass balance buoy deployed in april 2010 by the north pole environmental observatory program (identified as imb 2010a; timmermans et al. 2011) and 38 buoys archived by the iabp. the iabp data cannot resolve the full range of the frequency-domain signal of ice drift because (1) the data were only archived at 12 or 24 h intervals and (2) early data have low spatial accuracy (ca. 150 m) because of buoy positioning using the argos system instead of gps. the higher resolution data collected by buoys a�c and imb 2010a can be used to resolve the response of ice drift to local wind forcing, ice deformation and the frequency-domain signal of ice motion. by combining these data with the long-term iabp data sets, we inform on long-term changes in abbreviations in this article amsr-e: advanced microwave scanning radiometer�earth observing system ao: arctic oscillation da: arctic dipole anomaly gps: global positioning system iabp: international arctic buoy program mc: meander coefficient miz: marginal ice zone nao: north atlantic oscillation ncep/ncar: us national centers for environmental prediction/national center for atmospheric research tds: transpolar drift stream 60°w 60 °e 72°n 78°n 84°n historic data buoy a buoy b buoy c imb 2010 edge−mar. edge−may edge−jul. 0° 80°n 88°n north pole franz josef land svalbard fram strait greenland fig. 1 trajectories of buoys a�c, imb 2010a and historic buoys from 1979 to 2011 drifted from 888 to 808n, also shown are sea-ice edges from svalbard to greenland in march, may and july 2011. sea-ice kinematic in the arctic outflow region r. lei et al. 2 (page number not for citation purpose) citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 sea-ice kinematics from 1979 to 2011 and explore the response of sea ice to changing atmospheric circulation. methods and data the buoys deployed during 2010 (table 1) consisted of two compact air-launched metocean ice beacons (buoys a and b), one sea-ice measurement balance array unit from the scottish association for marine science (buoy c) and one metocean ice-mass balance buoy (imb 2010a). buoys a and b, and imb 2010a were equipped with a navman jupiter 32 gps receiver, with sampling intervals of 0.5 h. buoy c contained a fasttrax up501 gps receiver and a thermistor chain to resolve sea-ice mass balance, with sampling intervals of six hours. prior to deployment, the horizontal position accuracy for all gpss used in the chinese national arctic research expedition was calibrated onboard the icebreaker. the calibration took place over seven days with the maximum deviation of horizontal position among the gpss being below 15 m. prior to the calculation of ice-drift velocity, the buoyderived position data were linearly interpolated to the same temporal interval. according to leppäranta (2011), the accuracy dv of ice velocity is dv ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2 � s2=dt2 p ; (1) where s is the horizontal accuracy of the position and dt is the interpolation interval. the accuracy of daily and hourly ice velocity is therefore 0.0003 and 0.006 m s �1 , respectively. to characterize the frequency-domain signal of ice velocity, we applied fourier analysis using a fast fourier transformation algorithm for normalized hourly velocities of buoys a, b and 2010a. normalized velocities allow a better comparison among the frequency-domain signals, even when the absolute magnitude of ice velocity may change along the trajectory and among buoys. the normalized velocities were obtained by scaling the absolute values with the average values of a three-day sliding temporal window. the three-day sliding window was chosen as it suppresses the low-frequency signals from synoptic to seasonal scales and focuses on signals from hourly to daily. data from buoy c were not used for frequency-domain analysis because of its low sampling frequency. the frequency of inertial oscillation depends on the latitude of the particle: f0 ¼ 2x sin h; (2) where f0 is the inertial frequency, with an unit of cycle day �1 , v is the earth’ rotation rate (1.002736 cycles day �1 ) and u is the latitude. the inertial frequency ranges from 2.01 to 1.98 cycles day �1 between 908 and 808n. rotary spectra calculated from sea-ice velocity vector using complex fourier analysis were used to distinguish signals of inertial and tidal origin, both of which have an almost identical frequency close to two cycles day �1 in the arctic ocean. according to gimber, marsan et al. (2012), the complex fourier transformation _ uðxþ is defined as _ uðxþ¼ 1 n x tend�dt t¼t0 e�ixt ux þ iuy � � ; (3) where n and dt are the number and temporal interval of velocity samples, t0 and tend are the start and end of the temporal window, ux and uy are zonal and meridional ice speed at t�0.5dt and v is the angular frequency. assuming that sea ice can be represented as a homogeneous continuum, position measured by buoy arrays can be used to derive the divergence/convergence rate (d), shear rate (s) as well as the magnitude of the total deformation rate (o) of sea ice, calculated as the square root of d and s (herman & glowacki 2012). as the buoys a�c formed a triangle for most of their joint deployment, we use their position data to derive sea-ice deformation. however, as the buoys a and c remained in close proximity, while buoy b moved further away, the derived deformation rate exhibited large uncertainty. given this configuration, and following heil et al. (2008), divergence/convergence of the ice field was approximated by the changes in distance among a�c, hence dominated by mesoscale drivers. an independent data set was compiled to derive a broader picture of the long-term, seasonal and spatial table 1 operational history of 2010 buoys. buoy buoy type start date initial position stop date final position operation lifetime (d) drift distance (km) a caliba 18 aug 2010 87.338n, 160.708w 4 may 2011 76.588n, 3.458w 260 2983 b calib a 21 aug 2010 89.908n, 17.268e 23 mar 2011 81.888n, 1.558w 215 2596 c simba b 19 aug 2010 87.388n, 160.708w 23 jul 2011 72.398n, 18.838w 339 4300 2010a imb c 20 apr 2010 88.708n, 142.828e 1 dec 2010 77.588n, 1.778w 225 2294 a compact air-launched ice beacon. b sea-ice measurement balance array unit. c ice-mass balance buoy. ruibo lei et al. sea-ice kinematic in the arctic outflow region citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 changes in ice kinematics for the arctic outflow region. this data set consisted of positions collected by 42 icetethered buoys, deployed between 1979 and 2011 and drifting between 888 and 808n in the section from 608w to 608e. that included 38 buoys archived by the iabp combined with data from four 2010 buoys described above. daily ice velocities, averaged over one-degree zones from 888 to 808n for all buoys and all years, were used to estimate the seasonal and meridional variability. the mc of buoy trajectories (heil et al. 2008) was used to assess the effective ice advection, which in turn affects the residence time of sea ice within the arctic ocean. monthly mc was defined as the ratio of the cumulative distance along the trajectory determined by daily positions to the net displacement over one month. six-hourly data of 10-m wind speed and air temperature from the ncep/ncar reanalysis 2 (kanamitsu et al. 2002) were used to ascertain the local atmospheric forcing for the ice-tethered buoys. sea-ice concentration derived from daily amsr-e brightness temperatures (spreen et al. 2008) was used to determine local ice condition for the 2010 buoys, noting that north of 888n amsr-e data are not available. both data sets were bilinearly interpolated to the six-hourly positions of the buoys. the monthly ncep/ncar reanalysis 2 slp data above 708n from 1979 to 2011 were used to derive the empirical orthogonal function modes. the ao and the da correspond to the first and second leading modes of the empirical orthogonal function, respectively (wang & ikeda 2000; wu et al. 2006). here we analysed the empirical relationships between ice kinematic characteristics and monthly ao/da indices obtained from the same time to explore the responses of ice drift to atmospheric circulation. results results derived from the buoys deployed in 2010 operational history of buoys. after the deployments, driven by the tds all buoys drifted from the central arctic ocean, through fram strait into the greenland sea (fig. 1). because of an unusual atmospheric circulation pattern bringing a warm air mass over the arctic ocean during august 2010, a distinctly transpolar ice melt occurred late summer 2010, from the central arctic ocean into northern fram strait (kawaguchi et al. 2012). this resulted in relatively low ice concentration where the buoys a�c were deployed (lei et al. 2012) and over the summer section of imb 2010a’s track. upon deployment, the sites of buoys a�c encountered ice melt with surface air temperatures (ta) close to or above the freezing point. from mid-september 2010 onwards, the daily average ta remained below 08c through the entire life of buoy b, except for few episodic warm events. for buoys a and c, ta rose above 08c again in late may 2011. thermistor chain measurements taken by buoy c demonstrated that thermodynamic ice growth occurred from early october 2010 to mid-may 2011. at the imb 2010a site, ta increased continuously from april to mid-june 2010, then fluctuated around 08c until late august 2010, when it decreased gradually as winter approached. the operational lives of buoys a�c and imb 2010a ended in may 2011, march 2011, july 2011 and december 2010, respectively, coinciding with their drift into the miz. sea-ice velocity. the six-hourly magnitude of buoyderived ice velocity ranged from 0.01 to 0.64 m s �1 and increased as the ice moved into the fram strait. mean ice velocity (0.1590.12 m s �1 ) here was about twice the average ice velocity for the entire arctic ocean (zhang et al. 2012). generally less than 0.2 m s �1 , the absolute zonal velocities were much smaller than the meridional velocities. the mean ratio between meridional and zonal velocities ranged from 1.14 to 1.64. once the buoys had advanced into the fram strait (828 to 788n), these ratios increased markedly, with mean values of 3.14, 2.34, 1.50 and 2.13 for buoys a�c and imb 2010a, respectively. in contrast to buoys a, b and imb 2010a, which traversed the eastern edge of the fram strait and subsequently entered into the miz, buoy c drifted further to the west. from there it merged into the east greenland current, where it encountered compact sea ice. because buoys a and c remained close to each other while north of 818n, with a separation of 34�62 km, their mean velocities traced each other well except while moving between 848 and 838n (fig. 2). monthly correlation coefficients of ice and wind speed of a and c remained high (above 0.9; pb0.01; fig. 3). their divergence in mean velocity was noted between 848 and 838n (fig. 3), which was associated with the buoys being exposed to different wind streams during a cyclone event. buoy c was subject to an easterly surface wind and, consequently, its trajectory was more meandrous than that of buoy a. once south of 818n, buoy c progressed into an area of higher ice concentration and experienced less ocean-derived acceleration than buoy a. between 908 and 888n buoy b was exposed to nearly double the wind speed as buoys a and c. consequently, it moved at about 1.5�1.9 times their rate during october 2010 (fig. 3). between 888 and 858n, the velocity of sea-ice kinematic in the arctic outflow region r. lei et al. 4 (page number not for citation purpose) citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 buoy b was close to those of a and c; however, between 858 and 838n, buoy b slowed compared to a and c. this was likely related to the buoys moving in different wind regimes associated with a meso-scale cyclone, at times diverting buoy b into a northerly wind regime, while buoys a and c almost exclusively experienced southerlies. south of 828n, the velocity of buoy b exceeded those of a and c, associated with its drift within the eastern section of the fram strait. imb 2010a also clearly accelerated as it moved from the central arctic ocean into fram strait. responses to surface wind. statistical relationships between sea-ice drift and surface wind speed based on 2 may 2010 21 jun. 2010 10 aug. 2010 29 sep. 2010 18 nov. 2010 7 jan. 2011 26 feb. 2011 17 apr. 2011 6 jun. 2011 78 80 82 84 86 88 90 date l a tit u d e ( °n ) 0 0.1 0.2 0.3 0.4 0.5 buoy a buoy b buoy c imb 2010a absolute ice velocity (m/s) fig. 2 variations in sea-ice velocities measured by buoys a�c and imb 2010a. sep. oct. nov. dec. jan. feb. mar. apr. 0.2 0.4 0.6 0.8 1 c o rr e la tio n c o e ff ic ie n t o f w in d s p e e d sep. oct. nov. dec. jan. feb. mar. apr. 0.2 0.4 0.6 0.8 1 month c o rr e la tio n c o e ff ic ie n t o f ic e v e lo ci ty a vs. b a vs. c b vs. c p<0.01 (b) (a) p< 0.01 p<0.01 20112010 fig. 3 monthly correlation coefficients of wind speeds (a) and ice velocities (b) among buoy pairs of a, b and c, and dashed lines represent the 99% significance level. ruibo lei et al. sea-ice kinematic in the arctic outflow region citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 six-hourly data are summarized in table 2. north of 848n, the ice drift speed was 1.6�2.2% of surface wind speed. the ratios increased markedly as the buoys drifted southward, to 1.9�3.0% at 808�848n and finally to 3.3�8.8% south of 808n, which is larger than any results obtained from other arctic regions. the initial increase was associated with increasing magnitude in wind speed, while the increased magnitude of the southward oceanic surface current was the likely driver to the high ratio through fram strait. the correlation coefficients between ice drift and surface wind speed north of fram strait were always larger than in fram strait, except for imb 2010a. north of 808n, the correlation coefficient at imb 2010a was relatively low because of lower wind speeds at this buoy. the different response of ice drift at imb 2010a to wind forcing highlights the seasonality of the wind regime. ice drift can be classified by the absolute value of the turning angle between the ice-drift vector and the wind heading, following vihma et al. (1996). angles within 458 were assigned as ‘‘with wind heading’’; angles between 458 and 1358 as ‘‘perpendicular to wind heading’’; and angles larger than 1358 as ‘‘against wind heading.’’ north of fram strait, the majority of ice drift (42.1�82.4%) was in the direction of the wind. in fram strait, the relatively intense surface oceanic current dominated over the wind forcing, giving rise to a persistent southward ice drift, irrespective of the wind direction. in the case defined as ‘‘with wind heading,’’ the turning angle between ice drift and wind heading ranged from 108 to 228 north of fram strait. this range was close to those obtained in the arctic tds region during 2007�09 (58�188; haller et al. 2014). as expected, the ice speed with wind heading exceeded that perpendicular to or against the wind heading. illustrated by buoy a, there was no dominant wind direction during october 2010, december 2010 and january 2011, which resulted in a relatively broad directional distribution of the ice vectors (fig. 4). in november 2010 and march 2011, the ice vectors remained within a narrow range around 208 to the right of the wind in agreement with a tight wind heading. consequently, the drift trajectory was more streamlined. during february 2011, table 2 statistical relationships between ice drift and surface wind vectors for the 2010 buoys. ice drift with wind ice drift perpendicular to wind ice drift in opposition to wind ra a (%) r b p c (%) v d (m s �1 ) a e (8) cp (%) dv (m s �1) cp (%) dv (m s�1) a �848n 18 aug�16 mar 1.6 0.72 68.0 0.12 (90.07) 19 28.0 0.08 (90.06) 4.0 0.03 (90.02) 808�848n 16 mar�16 apr 2.9 0.80 77.1 0.22 (90.12) 15 22.1 0.12 (90.05) 0.8 0.05 (90.00) 768�808n 16 apr�5 may 3.3 0.11 43.7 0.27 (90.13) 1 33.8 0.31 (90.18) 22.5 0.28 (90.13) b �848n 21 aug�4 jan 1.7 0.84 67.4 0.12 (90.07) 22 31.6 0.09 (90.05) 1.0 0.03 (90.01) 808�848n 4 jan�11 mar 1.9 0.84 72.0 0.17 (90.13) 19 26.0 0.11 (90.09) 2.0 0.04 (90.03) 76�808n 11 mar�23 mar 4.5 0.15 68.1 0.38 (90.16) 18 31.9 0.36 (90.16) 0.0 * c �848n 19 aug�18 mar 1.8 0.57 65.6 0.12 (90.07) 18 28.8 0.09 (90.07) 6.6 0.05 (90.03) 808�848n 18 mar�28apr 2.7 0.58 69.3 0.18 (90.08) 14 26.8 0.14 (90.07) 4.9 0.13 (90.09) 768�808n 28 apr�6 jun 3.3 0.17 43.6 0.21 (90.08) 20 38.5 0.18 (90.09) 17.9 0.13 (90.04) b768n 6 jun�23 jul 5.9 0.08 51.1 0.17 (90.07) 9 40.4 0.22 (90.16) 8.5 0.16 (90.11) imb 2010a �848n 4 apr�3 oct 2.2 0.35 42.1 0.11 (90.06) 11 44.7 0.10 (90.05) 13.2 0.07 (90.05) 808�848n 3 oct�15 nov 3.0 0.26 62.3 0.16 (90.06) 10 34.7 0.15 (90.07) 3.0 0.11 (90.06) 778�808n 15 nov�1 dec 8.8 0.29 58.2 0.25 (90.13) 7 19.4 0.25 (90.14) 22.4 0.20 (90.15) a ra is the ratio between ice speed and wind speed. b r is the correlation coefficient between ice speed and wind speed. c p is the probability of turning angle between ice drift and wind vectors. d v is the mean ice speed with sd in parentheses. e a is the turning angle between ice drift and wind heading, with a positive sign denoting the buoys moved to the right of wind heading. sea-ice kinematic in the arctic outflow region r. lei et al. 6 (page number not for citation purpose) citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 the dominant wind heading ranged from north to north-west, opposing the direction of the tds. this wind regime gave rise to two dominant ice-drift directions. overall, the net displacement of buoy a was only 16 km during all of february 2011. inertial oscillation. based on the fourier transformation, energy variance in the normalized sea-ice speed scalar was dominated by frequencies lower than 1.0 cycle day �1 and exhibited a clear secondary maximum at semidiurnal frequencies at about 2.0 cycles day �1 (fig. 5a). the motion amplitudes of sea-ice velocities after the complex fourier transformation show an asymmetrical pattern, with a distinct peak at the frequency of about �2 cycles day�1 (fig. 5b), implying an identical clockwise oscillation (heil et al. 2008; gimbert, marsan et al. 2012). the monotone oscillations of the buoys can be discerned from their tracks (fig. 6). this semi-diurnal signal was therefore largely due to the inertial response. the magnitudes of the peak energy for the semidiurnal frequency varied seasonally. for all buoys, the amplitudes of 12-h cycle reached the maxima in the summer time, that is, during 18�20, 20�23 and 10�12 august 2010 for the buoys a, b and imb 2010a, respectively. for buoys a and b, semi-diurnal variability was observed distinctly from august to september 2010 (fig. 6a�d). the inertially induced ice movement was damped with the advent of winter as ice concentration and internal stress increased. once buoys a and b drifted into the miz, where the ice concentration rapidly decreased, the normalized amplitude at semi-diurnal frequencies increased slightly. imb 2010a survived the summer within 888�848n. from late july onwards, the ice concentration near imb 2010a decreased rapidly to a minimum of 65% on 15 august 2010. in consequence, the normalized velocity amplitudes at semi-diurnal frequencies increased markedly and persisted because of relatively low stress among the floes until ice concentration increased from mid-september onwards (fig. 6e). this corroborates the results obtained from pan-arctic analysis by gimbert, marsan et al. (2012), who also found that the sea-ice inertial response was strongest during the melting season. when imb 2010a finally drifted into the miz, the velocity amplitude also increased slightly. sea-ice deformation. initially, buoys a�c formed an isosceles triangle (fig. 7). the area of the triangle remained stable prior to the end of february 2011. from the late december 2010 to late march 2011, once buoy b was south of 848n and accelerated, the triangle abc deformed. around the same time, the base of the triangle shrunk slightly as buoys a and c converged as they approached fram strait (fig. 8a). during march 2011, nw 12 6 sw se s s s s s s oct. [88.4–89.3°n, mc=2.03, da=0.25] nov. [87.5–88.4°n, mc=1.13, da=0.93] dec. [86.4–87.5°n, mc=1.80, da=0.67] (a) (b) (c) ne e n w nw 32 16 sw se ne e n w nw 15 9 sw se ne e n w nw 12 24 sw se jan. [85.6–86.7°n, mc=2.15, da=–0.28] feb. [85.6–86.4°n, mc=15.29, da=–1.51] mar. [82.1–85.7°n, mc=1.09, da=1.63] (d) (e) (f) ne e n w nw 8 16 sw se ne e n w nw 44 22 sw se ne e n w fig. 4 monthly direction distributions (%, scaled by numbers in red) of wind heading (black) and ice vector (blue) at buoy a from october 2010 to march 2011, with latitude ranges, mc and da index in brackets for each panel. ruibo lei et al. sea-ice kinematic in the arctic outflow region citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 the area enclosed by the three buoys reduced to about 10% of the initial size due to a shear driven by an accelerated southward drift of buoy b. generally, in fram strait, sea-ice convergence was induced by differential ice motion in zonal direction, while ice divergence arose from differential ice motion in the meridional direction. overall, lead creation during divergence and lead closure during convergence balanced each other, as seen by the −6 −4 −2 0 2 4 6 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 frequency (cycle day−1) a m p lit u d e ( m s− 1 ) −6 −4 −2 0 2 4 6 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 frequency (cycle day−1) a m p lit u d e ( − ) buoy a (18−20 aug.) buoy b (21−23 aug.) 2010a (10−12 aug.) (a) (b) fig. 5 amplitudes after fourier transformation of normalized (a) ice speed scalar and (b) ice velocity vector during times when the amplitudes of 12-h cycle reached the maxima through the buoys’ lives. 20’ 87°n 30’ 40’ 161°w 161.5°w 8 sep. 28 oct. 7 dec. 5 feb. 27 mar. 16 may 0 0.1 0.2 0.3 0.4 0.5 0.6 date n o rm a liz e d a m p lit u d e 20 35 50 65 80 95 110 ic e c o n ce n tr a tio n /% 40’ 50’ 90°n 0° 30°e 8 sep 28 oct. 7 dec. 5 feb. 27 mar. 16 may 0 0.1 0.2 0.3 0.4 0.5 0.6 date n o rm a liz e d a m p lit u d e 20 35 50 65 80 95 110 ic e c o n ce n tr a tio n /% 31 may 20 jul. 8 sep. 28 oct. 0 0.1 0.2 0.3 0.4 0.5 0.6 date, 2010 n o rm a liz e d a m p lit u d e 20 35 50 65 80 95 110 ic e c o n ce n tr a tio n /% 7°e 8°e 9°e 10°e 11°e 16’ 87°n 18’ 20’ 22’ (a) (b) (d) (c) (f) 18−20 aug. 21−23 aug. 10−12 aug. 2011 2010 2011 2010 (e) fig. 6 amplitude after fourier transformation corresponding to the 12-h cycle of the normalized velocities of buoys a, b and imb 2010a for a sliding three-day window and (b, d, e) ice concentrations near the buoys and (a, c, f) the tracks of the buoys when the above-mentioned amplitudes reached the maxima. sea-ice kinematic in the arctic outflow region r. lei et al. 8 (page number not for citation purpose) citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 near-constant ice concentration within the triangle enclosed by abc, which was reduced only once buoy b transited into the miz (fig. 8c). ice drift derived using data from 1979 to 2011 seasonal and spatial changes in sea-ice drift. using drift data acquired between 888 and 808n, and 608w and 608e, from the iabp archive and the buoys operating in 2010, irrespective of the year, the full picture of seasonal and spatial changes in sea-ice velocity can be obtained (fig. 9). the relatively homogeneous distribution of time when the buoy data were available ensured the validity of the interpolation. comparisons between the results derived from all buoys from 1979 to 2011 and those from the buoys in 2010 show that the ice speed in 2010 was slightly higher than the long-term average, but the discrepancy was not significant because their averages 91 sd overlap for all latitudinal zones (fig. 9d). thus, 2010 can be considered a representative year relative for the 1979�2011 climatology with view to ice motion in the arctic outflow region. the annual mean derived from the 1979�2011 data in 81�808n of 0.18 m s �1 was about double that in 88�848n of 0.08�0.10 m s�1 (fig. 9d). these values were close to those obtained from a buoy array operating in the arctic outflow region during 2007�09, given by haller et al. (2014). they obtained the ice velocities of 0.08 m s �1 north of 858n and 0.21 m s�1 in fram strait. distinct increases in both the magnitude and standard deviation of the annual mean ice velocity derived from the 1979 to 2011 data occurred from 848 to 808n (fig. 9d). the southward increase in the standard deviation can be attributed to the enhanced seasonal amplitude of ice velocity south of 848n. sea-ice speed increased from september to the following may (fig. 9b). this seasonal pattern was related to the seasonality of surface wind. 60°w 6 0° e 88°n track of a track of b track of c 25/8/10 24/9/10 24/10/10 23/11/10 23/12/10 22/1/11 21/2/11 23/3/11 22/4/11 2/5/11 greenland 0° 84°n svalbard barents sea greenland sea 80°n 76°n fram strait lincoln sea fig. 7 trajectories of buoys a, b and c with 30-day positions. 200 300 400 500 600 d is ta n ce o f a b & b c /k m 32 40 48 56 64 d is ta n ce o f a c /k m 2000 4000 6000 8000 10000 a re a o f a b c /k m 2 6 nov. 6 dec. 5 jan. 4 feb. 6 mar. 91 93 95 97 99 101 date s e a ic e co n ce n tr a tio n /% ab bc ac (a) (b) 2010 2011 (c) fig. 8 (a) distances of buoy pairs among a, b and c, noted that the distance between d and b refers to the right y axis, and others refer to the left y axis; (b) area of the triangle a�b�c; and (c) sea-ice concentration within the triangle a�b�c. ruibo lei et al. sea-ice kinematic in the arctic outflow region citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 from september to may, the surface wind in the region was directed to the south, and the speed was relatively high from october to march, likely enhancing the tds and increasing the southward ice velocity. contrarily, during summer (june to august), the direction of the winds almost reversed against the dominant direction of tds. ice velocity was therefore relatively low during this time. for the buoys in 2010, the relatively slow drift of imb 2010a compared with the buoys a�c was consistent with this seasonality (fig. 2). associated with relatively high ice concentration in winter, the seasonal changes in sea-ice area outflow through fram strait can be markedly enhanced. this explains the low contribution from june to september, accounting only about 13%, to the annual sea-ice area outflow through fram strait (kwok 2009). long-term changes in sea-ice drift and responses to atmospheric circulation. based on the long-term data set between 1979 and 2011, the mean travel time of sea ice from 888 to 808n in the arctic section of 608 to 608e was 183 (950) days (fig. 10a). the mean travel time of the 2010 buoys was 154 (929) days, which was shorter than the long-term average, but within the 1 sd of the long-term average. this again indicates that 2010 was a representative year. the linear regression shows that the long-term trend in the ice travel time from 1979 to 2011 was -0.05 days decade �1 . however, this longterm trend was not statistically significant even at the 95% confidence level. contrarily, the travel time shows high year-to-year variability, with the maximum roughly four times the minimum, because sea-ice export was highly promoted (restricted) during positive (negative) da (wang et al. 2009). about 31% of the variations in ice travel time from 888 to 808n can be explained by the monthly da index at the 99.9% significance level (fig. 10b). the mean ice travel time in the positive regime of da was 157 days (27 records), relative to 218 days in the negative regime of da (15 records). using pearson correlation analysis, we found that higher da index coincided with relatively large meridional ice velocities (pb0.001; table 3), which was associated with a relatively small mc of ice drift (pb0.01). a strong positive (negative) phase of the ao was associated with a relatively large zonal cyclonic (anticyclonic) surface wind anomaly (proshutinsky & johnson 1997). there was a significant relationship between the ao and zonal ice velocity (pb0.05). however, as the ice travel time was largely dependent on meridional ice velocity fig. 9 (a) seasonal changes in one-latitude average daily ice-drift speed with pluses denoting the time when original data were available, (b) seasonal changes in meridional average ice-drift speed from 858 to 808n, (c) surface wind speed heading to the north in the section of 608w to 608e and (d) meridional changes in averaged ice-drift speed from 808 to 888n (red for the buoys from 1979 to 2011 and blue for the buoys in 2010). sea-ice kinematic in the arctic outflow region r. lei et al. 10 (page number not for citation purpose) citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 (pb0.001), the relationship between the ao index and ice travel time was statistically insignificant even at the 95% confidence level. to explore the regional dependence of the relationship between the mc of ice drift and the da index, we plotted all mcs against the latitudes and the monthly da indices regardless of the year (fig. 11). we found a spatial boundary at about 828n. north of this latitude, the dependence of the mc on the da index was stronger and both correlated well (r �0.41, pb0.001). in the high positive da phase (�1.0) north of 828n, the mean mc was 1.4 and the ice trajectories were more direct. in contrast, in the high negative phase of the da (b�1.0), the mean mc was 4.3 and the ice drift trajectories were more meandering. for the neutral da from �1.0 to 1.0, the mean mc was 1.9. south of 828n, the meridional ice advection was more direct (mean mc of 1.3), regardless of the magnitude or phase of the da index. this can 790525 841114 900507 951028 010419 061010 120404 −1.5 −1 −0.5 0 0.5 1 1.5 date (yymmdd) m o n th ly d a in d e x 80 120 160 200 240 280 320 t ra ve l t im e ( d ) −1.2 −0.9 −0.6 −0.3 0 0.3 0.6 0.9 1.2 1.5 60 120 180 240 300 360 monthly da index t ra ve l t im e ( d ) 80 110 140 170 200 230 260 290 320 −2 −1.5 −1 −0.5 0 0.5 1 1.5 n e t in cr e a se o f se a ic e e xt e n t (´ 1 0 6 k m 2 ) 400 600 800 1000 travel time (d) a re a f lu x (x 1 0 3 k m 2 ) a re a f lu x (x 1 0 3 k m 2 ) (b) r=−0.65 p<0.001 r=0.41 p<0.01 (a) 1060 950 840 730 620 510 400 r=−0.56 p<0.001 (c) fig. 10 (a) monthly da index (left y axis, black line), travel time from 888 to 808n of the buoys (right y axis, red line) from 1979 to 2011 and annual arctic sea-ice area flux through fram strait from 1992 to 2007 (right y axis, blue line); (b) linear regression of ice travel time against monthly da index and (c) linear regressions of year-to-year net increase in summer minimum of arctic sea-ice extent (left y-axis) and annual arctic sea-ice area flux through fram strait (right y axis) against the travel time of the buoys. table 3 pearson correlation coefficients between pair parameters. significance levels are pb0.001 (***), pb0.01 (**) and pb0.05 (*); n.s. denotes not significant at the 0.05 significance level. ta m rv uy ux da m b 0.81*** rv c �0.68*** �0.81*** uy d �0.77*** �0.64*** 0.79*** ux e n.s. n.s. n.s. n.s. da f �0.56*** �0.52** 0.53** 0.59*** n.s. ao g n.s. n.s. n.s. n.s. 0.34* n.s. at is the ice travel time from 888 to 808n. bm is the mean mc from 888 to 808n. crv is the ratio between meridional and zonal ice velocities. d,euy and ux are meridional and zonal ice velocities from 888 to 808n. f,gda/ao are the monthly da/ac indices. ruibo lei et al. sea-ice kinematic in the arctic outflow region citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 be attributed to the marked increase in meridional ice velocity (fig. 9d) due to direct forcing by the relatively fast surface oceanic current through fram strait. to explore the relationship between the intensity of tds and the decline of arctic sea ice, we combined our data with results of the annual sea-ice area outflow through fram strait from 1992 to 2007 given by kwok (2009) and calculated the year-to-year net change of summer minimum arctic sea-ice extent. the net change of arctic summer sea-ice extent was defined as the deviation between minimum arctic sea-ice extents from a given year to the previous one. we found that a stronger tds (shorter ice travel time from the central arctic to fram strait) was associated with an increased sea-ice area outflow through fram strait (r �0.65, pb0.001) and a decline in arctic summer sea-ice extent (r �0.41, pb0.01). for the extreme years of 1994�95, when the sea-ice area outflow through fram strait reached its maximum for 1992�2007, the mean monthly da index and ice travel time from 888 to 808n (obtained from three buoys) were 0.7 and 128 days, respectively. consequently, the annual minimum arctic sea-ice extent in september 1995 reached a record minimum since 1979. relative to the 1994 summer, the net loss of annual minimum arctic sea-ice extent in 1995 was 0.94 �106 km2. contrarily, in 2002�03, when the sea-ice area outflow through the fram strait reached minimum for 1992�2007, the monthly da index and mean ice travel time (obtained from two buoys) were �0.2 and 282 days, respectively. the net increase of annual minimum arctic sea-ice extent in 2003 relative to 2002 was 0.35 �106 km2. thereafter, the annual minimum sea-ice extent reached a record minimum again in the 2005 and 2007 summers. the mean travel times were 129 days (obtained from two buoys) and 158 days (obtained from four buoys), during 2004�05 and 2006�07, respectively. both were clearly less than the long-term average (183 days) from 1979 to 2011. the persistent positive polarity of the da since 2005, with a mean monthly da index of 0.62 (90.35), might give rise to the relatively short travel time of the floes from the central arctic ocean to fram strait, averaging 156 (922) days. all years from 2005 to 2011 exhibited ice export faster than the long-term mean from 1979 to 2011, with only one exception (2008; 203 days), when the summer sea-ice extent showed a large recovery relative to the 2007 minimum. this suggests that the high ice outflow through fram strait played a significant role to accelerate the decline of the arctic sea ice during recent years. however, the state since 2005 cannot be defined as a new normal, as similar high ice outflow rates were also observed in previous years, for example in the late 1980s and the mid-1990s. discussion and conclusions over an operational lifetime of 7�11 months from the arctic outflow region into fram strait, six-hourly ice velocities derived from four buoys deployed in 2010 ranged from 0.01 to 0.64 m s �1 with an average of 0.15 (90.12) m s �1 . daily ice velocities were slightly reduced −3 −2.5 −2 −1.5 −1 −0.5 0 0.5 1 1.5 2 2.5 80 82 84 86 88 90 monthly da index l a tit u d e °n 1.6 2.5 4.0 6.3 10 15.8 case 2 mc=1.9 case 1 mc=4.3 case 4 mc=1.3 case 3 mc=1.4 meander coefficient fig. 11 mc against latitude and monthly da index for all buoys from 1979 to 2011; the red dashed lines divide the data into four cases: (1) with high negative da north of 828n, (2) with neutral da north of 828n, (3) with high positive da north of 828n and (4) south of 828n; also shown are the average mcs for various cases; the colour bar for mc was shown at a logarithmic scale. sea-ice kinematic in the arctic outflow region r. lei et al. 12 (page number not for citation purpose) citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 to 0.13 (90.09) m s �1 because of sub-diurnal meandering. their travel time from 888 to 808n was 154 (929) days. while the long-term averages of daily ice velocities and travel time in arctic outflow region (888�808n) from 1979 to 2011 were 0.10 (90.08) m s �1 and 183 (950) days, respectively. this implies that ice drift in this region for 2010�11 had increased slightly compared to the previous three decades, but still a normal state. we measured a mean ice velocity in the arctic outflow region about twice the arctic ocean average (zhang et al. 2012). the data from 1979 to 2011 do not show any statistically significant long-term trend at the 95% significance level. based on the comparison with the drift of the norwegian vessel fram 100 years ago, gascard et al. (2008) and haller et al. (2014) declared that the tds has roughly doubled during 2007�09. however, the 1979� 2011 data used here show that the relatively rapid tds after 2005 cannot be defined as a new normal instead being a transient characteristic of the system, as similar high ice outflow rates were also observed in the late 1980s and the mid-1990s. the strength of sea-ice outflow from the central arctic ocean to fram strait can be partially explained by the polarity of the da (31%). the persistent positive phase of the da since 2005 was associated with the relatively short travel time of sea ice, and consequently the accelerated decline of summer arctic sea ice in recent years. we found a significant relationship (r �0.41, pb0.01) between sea-ice travel time from the central arctic ocean to fram strait and the year-to-year variability in minimum arctic sea-ice extent. this lends further credibility to a conclusion that the tds is a crucial factor determining the changes in arctic sea ice (e.g., kwok 2009; wang et al. 2009; wang et al. 2014). north of fram strait, ice drift was closely coupled to the surface wind forcing, as seen by the strong correlation between ice velocity and wind speed, and a high probability of ice drifting with the wind. the impact on ice drift by the da-derived anomalous meridional wind was therefore stronger in the region north of 828n. a negative da resulted in a wind direction against the tds, and consequently increased the mc of the ice drift, and vice versa, during the positive phase of the da. once the ice had drifted towards and into fram strait, ice velocities increased markedly (about two to three times), due to the increase of the surface ocean current. this reduced response of ice drift to da was associated with a decrease in ice meandering through fram strait. sea-ice deformation also increased markedly as the floes congregated and drifted rapidly through fram strait. deformation was characterized by meridional divergence and zonal convergence. we suggest that south of 858n, the distinct seasonal signal in the meridional wind velocity could possibly be linked to the seasonal pattern of arctic sea-ice export through fram strait. in this region, the sea-ice velocity was relatively large from september to the following may. however, for two sub-data sets: six cases drifting from 848 to 808n during june to august, and 26 cases during september to the following may, their average travel times from 888 to 808n were 182952 and 177946 days, respectively. the difference was much less than 1 sd for both data sets. we therefore argue that interannual variability in ice travel time from the central arctic ocean to fram strait exceeded the seasonal change. during summer, ice velocities exhibited a strong semidiurnal signal. the result after the complex fourier transformation of ice velocity indicates that this semidiurnal signal was largely due to enhanced inertial response when the sea ice was less concentrated and there was less cohesion among the floes. in summer, the ratio of ice speed to wind speed was also larger, because of the enhanced free motion of floes. as winter approached, this semi-diurnal signal was quickly dampened by increased internal stress among the floes. acknowledgements this work was financially supported by grants from the national natural science foundation of china (no. 41476170), the chinese polar environment comprehensive investigation and assessment programs (no. chinare 2015-04-03/04-04/03-01) and marine public industry research of china (no. 201205007). sea-ice concentration was provided by the university of bremen (www.iup.unibremen.de:8084/amsr/amsre.html). iabp and their contributors are thanked for sharing buoy data (www.iabp.apl. washington.edu/). ph was supported under an australian antarctic science grant (no. 4472) and by the australian government’s cooperative research centres programme through the antarctic climate and ecosystems cooperative research centre. jw was supported by the national oceanic and atmospheric administration office of arctic research (grant no. 1755). we also thank the anonymous reviewers for their comments, and s. lake and c. darnell for editing the manuscript. references comiso j.c. 2012. large decadal decline of the arctic multiyear ice cover. journal of climate 25, 1176�1193. cox k.a., stanford j.d., mcvicar a.j., rohling e.j., heywood k.j., bacon s., bolshaw m., dodd p. a., de la rosa s. & wilkinson d. 2010. interannual variability of arctic sea ice ruibo lei et al. sea-ice kinematic in the arctic outflow region citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 13 (page number not for citation purpose) http://www.iup.uni-bremen.de:8084/amsr/amsre.html http://www.iup.uni-bremen.de:8084/amsr/amsre.html http://www.iabp.apl.washington.edu/ http://www.iabp.apl.washington.edu/ http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 export into the east greenland current. journal of geophysical research*oceans 115, c12063, doi: http://dx.doi.org/10. 1029/2010jc006227 gascard j.-c., festy j., le goff h., weber m., brümmer b., offermann m., doble m., wadhams p., forsberg r., hanson s., skourup h., gerland s., nicolaus m., metaxian j.-p., grangeon j., haapala j., rinne e., haas c., heygster g., jacobson e., palo t., wilkinson j., kaleschke l., claffey k., elder b. & bottenheim j. 2008. exploring arctic transpolar drift during dramatic sea ice retreat. eos, transactions of the american geophysical union 89, 21�28. gimbert f., jourdain n.c., marsan d., weiss j. & barnier b. 2012. recent mechanical weakening of the arctic sea ice cover as revealed from larger inertial oscillations. journal of geophysical research*oceans 117, c00j12, doi: http://dx.doi. org/10.1029/2011jc007633 gimbert f., marsan d., weiss j., jourdain n.c. & barnier b. 2012. sea ice inertial oscillations in the arctic basin. the cryosphere 6, 1187�1201. hakkinen s., proshutinsky a. & ashik i. 2008. sea ice drift in the arctic since the 1950s. geophysical research letters 35, l19704, doi: http://dx.doi.org/10.1029/2008gl034791 haller m., brümmer b. & müller g. 2014. atmosphere�ice forcing in the transpolar drift stream: results from the damocles ice-buoy campaigns 2007�2009. the cryosphere 8, 275�288. heil p. & hibler w.d., iii. 2002. modeling the high-frequency component of arctic sea ice drift and deformation. journal of physical oceanography 32, 3039�3057. heil p., hutchings j.k., worby a.p., johansson m., launiainen j., haas c. & hibler w.d., iii. 2008. tidal forcing on sea-ice drift and deformation in the western weddell sea in early austral summer 2004. deep-sea research part ii 55, 943�962. herman a. & glowacki o. 2012. variability of sea ice deformation rates in the arctic and their relationship with basin-scale wind forcing. the cryosphere 6, 1553�1559. hilmer m. & jung t. 2000. evidence for a recent change in the link between the north atlantic oscillation and arctic sea ice export. geophysical research letters 27, 989�992. kanamitsu m., ebisuzaki w., woollen j., yang s., hnilo j.j., fiorino m. & potter g.l. 2002. ncep�doe amip-ii reanalysis (r-2). bulletin of the american meteorological society 83, 1631�1643. kawaguchi y., hutchings j.k., kikuchi t., morison j.h. & krishfield r.a. 2012. anomalous sea-ice reduction in the eurasian basin of the arctic ocean during summer 2010. polar science 6, 39�53. kwok r. 2009. outflow of arctic ocean sea ice into the greenland and barents seas: 1979�2007. journal of climate 22, 2438�2457. kwok r., spreen g. & pang s. 2013. arctic sea ice circulation and drift speed: decadal trends and ocean currents. journal of geophysical research*oceans 118, 2408�2425. lei r., zhang z., matero i., cheng b., li q. & huang w. 2012. reflection and transmission of irradiance by snow and sea ice in the central arctic ocean in summer 2010. polar research 31, article no. 17325, doi: http://dx.doi.org/10. 3402/polar.v31i0.17325 leppäranta m. 2011. the drift of sea ice. berlin: springer press. maslanik j., drobot s., fowler c., emery w. & barry r. 2007. on the arctic climate paradox and the continuing role of atmospheric circulation in affecting sea ice conditions. geophysical research letters 34, l03711, doi: http://dx.doi.org/ 10.1029/2006gl028269 nghiem s.v., rigor i.g., perovich d.k., clemente-colon p., weatherly j.w. & neumann g. 2007. rapid reduction of arctic perennial sea ice. geophysical research letters 34, l19504, doi: http://dx.doi.org/10.1029/2007gl031138 parkinson c.l. & comiso j.c. 2013. on the 2012 record low arctic sea ice cover: combined impact of preconditioning and an august storm. geophysical research letter 40, 1356�1361. proshutinsky a.y. & johnson m.a. 1997. two circulation regimes of the wind-driven arctic ocean. journal of geophysical research*oceans 102, 12493�12514. rampal p., weiss j. & marsan d. 2009. positive trend in the mean speed and deformation rate of arctic sea ice, 1979�2007. journal of geophysical research*oceans 114, c05013, doi: http:// dx.doi.org/10.1029/2008jc005066 rampal p., weiss j., marsan d., lindsay r. & stern h. 2008. scaling properties of sea ice deformation from buoy dispersion analysis. journal of geophysical research*oceans 113, c03002, doi: http://dx.doi.org/10.1029/2007jc004143 rigor i.g., wallace j.m. & colony r.l. 2002. response of sea ice to the arctic oscillation. journal of climate 15, 2648�2663. serreze m.c., barrett a.p., slater a.g., woodgate r.a., aagaard k., lammers r.b., steele m., moritz r., meredith m. & lee c.m. 2006. the large-scale freshwater cycle of the arctic. journal of geophysical research*oceans 111, c11010, doi: http://dx.doi.org/10.1029/2005jc003424 spreen g., kaleschke l. & heygster g. 2008. sea ice remote sensing using amsr-e 89 ghz channels. journal of geophysical research*oceans 113, c02s03, doi: http://dx.doi.org/10. 1029/2005jc003384 spreen g., kwok r. & menemenlis d. 2011. trends in arctic sea ice drift and role of wind forcing: 1992�2009. geophysical research letters 38, l19501, doi: http://dx.doi.org/10.1029/ 2011gl048970 stern h.l. & lindsay r.w. 2009. spatial scaling of arctic sea ice deformation. journal of geophysical research*oceans 114, c10017, doi: http://dx.doi.org/10.1029/2009jc005380 stouffer r.j., yin j., gregory j.m., dixon k.w., spelman m.j., hurlin w., weaver a.j., eby m., flato g.m., hasumi h., hu a., jungclaus j.h., kamenkovich i.v., levermann a., montoya m., murakami s., nawrath s., oka a., peltier w.r., robitaille d.y., sokolov a., vettoretti g. & weber s.l. 2006. investigating the causes of the response of the thermohaline circulation to past and future climate changes. journal of climate 19, 1365�1387. timmermans m.-l., proshutinsky a., krishfield r.a., perovich d.k., richter-menge j.a., stanton t.p. & toole j.m. 2011. surface freshening in the arctic ocean’s eurasian basin: an apparent consequence of recent change in the wind-driven sea-ice kinematic in the arctic outflow region r. lei et al. 14 (page number not for citation purpose) citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 http://dx.doi.org/10.1029/2010jc006227 http://dx.doi.org/10.1029/2010jc006227 http://dx.doi.org/10.1029/2011jc007633 http://dx.doi.org/10.1029/2011jc007633 http://dx.doi.org/10.1029/2008gl034791 http://dx.doi.org/10.3402/polar.v31i0.17325 http://dx.doi.org/10.3402/polar.v31i0.17325 http://dx.doi.org/10.1029/2006gl028269 http://dx.doi.org/10.1029/2006gl028269 http://dx.doi.org/10.1029/2007gl031138 http://dx.doi.org/10.1029/2008jc005066 http://dx.doi.org/10.1029/2008jc005066 http://dx.doi.org/10.1029/2007jc004143 http://dx.doi.org/10.1029/2005jc003424 http://dx.doi.org/10.1029/2005jc003384 http://dx.doi.org/10.1029/2005jc003384 http://dx.doi.org/10.1029/2011gl048970 http://dx.doi.org/10.1029/2011gl048970 http://dx.doi.org/10.1029/2009jc005380 http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 circulation. journal of geophysical research*oceans 116, c00d03, doi: http://dx.doi.org/10.1029/2011jc006975 tremblay l.-b. & mysak l.a. 1997. modeling sea ice as a granular material, including the dilatancy effect. journal of physical oceanography 27, 2342�2360. tsukernik m., deser c., alexander m. & tomas r. 2010. atmospheric forcing of fram strait sea ice export: a closer look. climate dynamics 35, 1349�1360. vihma t., launiainen j. & uotila j. 1996. weddell sea ice drift: kinematics and wind forcing. journal of geophysical research* oceans 101, 18279�18296. vihma t., tisler p. & uotila p. 2012. atmospheric forcing on the drift of arctic sea ice in 1989�2009. geophysical research letters 39, l02501, doi: http://dx.doi.org/10.1029/2011gl050118 wang j., eicken h., yu y., bai x., zhang j., hu h., wang d.-r., ikeda m., mizobata k. & overland j.e. 2014. abrupt climate changes and emerging ice�ocean processes in the pacific arctic region and the bering sea. in j.m. grebmeier & w. maslowski (eds.): the pacific arctic region: ecosystem status and trends in a rapidly changing environment. pp. 65�100. dordrecht: springer. wang j. & ikeda m. 2000. arctic oscillation and arctic sea-ice oscillation. geophysical research letters 27, 1287�1290. wang j., zhang j., watanabe e., mizobata k., ikeda m., walsh j.e., bai x. & wu b. 2009. is the dipole anomaly a major driver to record lows in the arctic sea ice extent? geophysical research letters 36, l05706, doi: http://dx.doi.org/10.1029/ 2008gl036706 wu b., wang j. & walsh j.e. 2006. dipole anomaly in the winter arctic atmosphere and its association with arctic sea ice motion. journal of climate 19, 210�225. zhang j., lindsay r., schweiger a. & rigor i. 2012. recent changes in the dynamic properties of declining arctic sea ice: a model study. geophysical research letters 39, l20503, doi: http://dx.doi.org/10.1029/2012gl053545 zhang j., woodgate r. & moritz r. 2010. sea ice response to atmospheric and oceanic forcing in the bering sea. journal of physical oceanography 40, 1729�1747. ruibo lei et al. sea-ice kinematic in the arctic outflow region citation: polar research 2016, 35, 22658, http://dx.doi.org/10.3402/polar.v35.22658 15 (page number not for citation purpose) http://dx.doi.org/10.1029/2011jc006975 http://dx.doi.org/10.1029/2011gl050118 http://dx.doi.org/10.1029/2008gl036706 http://dx.doi.org/10.1029/2008gl036706 http://dx.doi.org/10.1029/2012gl053545 http://www.polarresearch.net/index.php/polar/article/view/22658 http://dx.doi.org/10.3402/polar.v35.22658 the last two millennia: climate, ocean circulation and palaeoproductivity inferred from planktic foraminifera, south-western svalbard margin research article the last two millennia: climate, ocean circulation and palaeoproductivity inferred from planktic foraminifera, south-western svalbard margin   katarzyna zamelczyk,1 tine l. rasmussen,1 markus raitzsch2,3 & melissa chierici4 1centre for arctic gas hydrate, environment and climate, department of geoscience, uit—the arctic university of norway, tromsø, norway; 2marum—center for marine environmental sciences, university of bremen, bremen, germany; 3alfred wegener institute helmholtz centre for polar and marine research, bremerhaven, germany; 4institute of marine research, fram centre, tromsø, norway abstract we reconstruct climate and changes in water-mass properties in relation to variations in palaeoproductivity at the south-western svalbard margin throughout the last 2000 years. environmental conditions in subsurface (ca. 250–75 m) and near-surface to surface water (75–0 m) were studied on the basis of the distribution patterns and fluxes of planktic foraminiferal faunas. stable isotopes in three different species were measured, and mg/caand transfer function-based sea-surface temperatures were calculated. the mean shell weights of planktic foraminiferal species were used to assess changes in calcium carbonate preservation. modern total planktic foraminiferal distribution patterns from plankton tows and the water column carbonate chemistry were investigated for comparison with the palaeo-data. the results show warm sea-surface conditions and moderate to high surface productivity at ca. 21–400 ad, ca. 900–1400 ad and from about 1850 ad until present, which may be local expressions of the european climatic events known as the roman warm period, the medieval climate anomaly and the recent warming. in general, cold near-sea-surface conditions and very low to moderate average productivity occurred at about 400–900 ad and ca. 1400–1850 ad, the latter probably the local expression of the little ice age. the highest and most variable planktic productivity occurred at ca. 1300–1500 ad, ca. 1750–1860 ad and during the last 50 years or so. these periods are linked to the general amelioration of conditions from years with a dense sea-ice cover to years with a rapidly fluctuating summer sea-ice margin. keywords late holocene; fram strait; arctic hydrography; sea-surface/subsurface palaeoenvironments; storfjorden fan abbreviations ad: anno domini ams: accelerator mass spectrometry at: total alkalinity bc: before christ ct: total dissolved inorganic carbon ctd: conductivity–temperature–depth instrument ird: ice-rafted debris ky−1: per thousand years smow: standard mean ocean water sr: sedimentation rate sst: sea-surface temperature tc: total carbon toc: total organic carbon uit: uit—the arctic university of norway, tromsø vindta: versatile instrument for the determination of total inorganic carbon and titration alkalinity (laboratory alkalinity titration system) v-pdb: vienna pee dee belemnite (reference standard for carbon isotopes) v-smow: vienna standard mean ocean water wsc: west spitsbergen current citation: polar research 2020, 39, 3715, http://dx.doi.org/10.33265/polar.v39.3715 copyright: polar research 2020. © 2020 k. zamelczyk et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 19 october 2020 competing interests and funding: the authors report no conflict of interest. the study was carried out within the framework of the project effects of ocean chemistry changes on planktic foraminifera in the fram strait: ocean acidification from natural to anthropogenic changes, funded by the research council of norway (project no. 216538), the centre for arctic gas hydrate, environment and climate, supported by the research council of norway (project no. 223259) and uit. this study was also supported by the ocean acidification flagship within the fram—high north centre for climate and the environment, norway. in addition, the publication was supported by the publication fund of uit. correspondence to: katarzyna zamelczyk, centre for arctic gas hydrate, environment and climate, department of geoscience, uit—the arctic university of norway, dramsveien 201, no-9037 tromsø, norway. e-mail: katarzyna.zamelczyk@uit.no to access the supplementary material, please visit the article landing page introduction warm and saline atlantic surface water transported to the nordic seas undergoes cooling in winter during northward flow in the norwegian current. in some areas, such as the greenland sea, the dense surface water subsequently sinks to form cold deep water. further north the warm atlantic water meets the cold water flowing southward from the arctic ocean. the two water masses form a front, referred to as the polar front (rudels 1996; rudels et al. 2000). the mixing of these two water masses introduces nutrients into the euphotic zone, generating the most productive surface waters of the nordic seas and fram strait (smith et al. 1987; smith & sakshaug 1990). the flow of warm atlantic water via the wsc into the arctic ocean is considered a major controlling factor of climate and the location of the sea-ice margin and therefore of the surface water productivity in fram strait (e.g., walczowski & piechura 2011; beszczynska-möller et al. 2012; walczowski et al. 2017). numerous studies have examined changes in circulation, productivity and properties of the atlantic water in the nordic seas during the holocene and the past glacial period (e.g., rasmussen et al. 2003; ellingsen et al. 2008; müller et al. 2012; pathirana et al. 2015; hoff et al. 2016; berben et al. 2017). as only a few high-resolution studies in the arctic areas have been undertaken (wollenburg et al. 2004; majewski et al. 2009; spielhagen et al. 2011; werner et al. 2011; pawłowska et al. 2016), knowledge regarding the natural variability in ocean surface conditions and surface productivity for the last two millennia before the last 150 years is still scarce. variations in the inflow of warm atlantic water, its mixing with cold polar water and the resulting changes in productivity were probably controlled by natural climate anomalies before human impact became a dominant factor (e.g., spielhagen et al. 2011; pathirana et al. 2015; pawłowska et al. 2016). the purpose of the present study is to reconstruct the properties of the upper approximately 250 m of the water column in fram strait, focusing on the south-western svalbard margin (76 °n) and the development over historical times (the past 2000 years) to get a better understanding of the properties of the atlantic water, its interactions with polar surface water, meltwater and associated productivity changes in relation to climate change. box core hh12-1206bc from storfjorden fan, south-west of svalbard, was taken in the atlantic water domain of fram strait and close to the present arctic front, where atlantic and polar water meet and mix (fig. 1). this study is based on the distribution patterns of planktic foraminifera, the concentration and flux of the total foraminiferal fauna and individual species used as indications of productivity change, along with reconstructions of absolute ssts (mg/ca ratios and transfer functions). furthermore, based on the main depth habitats of the planktic foraminiferal species neogloboquadrina pachyderma and turborotalita quinqueloba, we use the difference in the δ18o values between n. pachyderma and t. quinqueloba (δδ18onp-tq) as a proxy for increased/decreased presence of atlantic water (sensu moffa-sánchez & hall 2017). to investigate the reliability of our palaeo-reconstructions, we use dissolution proxies and other geochemical and sedimentological data to assess changes in preservation of the specimens. dissolution may severely influence the faunal composition (berger 1970; le & thunell 1996), mg/ca ratios (e.g., nürnberg 1995), temperature estimates based on transfer functions (e.g., imbrie & kipp 1971) and faunal concentrations (berger 1970; thunell & honjo 1981; vincent & berger 1981; peterson & prell 1985; conan et al. 2002; petró et al. 2018). to better compare the past with modern surface and productivity conditions, we also analysed living planktic foraminiferal faunas from plankton tows and the water carbonate chemistry. the results are compared to studies from other areas of the svalbard margin and the north atlantic and nordic seas to study the nature of climate, ocean circulation and palaeoproductivity changes in the arctic on a regional basis. fig. 1 (a) schematic map of northern north atlantic, fram strait and western barents sea showing bathymetry, present-day major surface currents and average position of polar and arctic fronts. (b) close-up of western svalbard margin, north-western barents sea. solid and dashed lines indicate surface and subsurface currents, respectively. location of core hh12-1206bc (green circle) is indicated together with published records discussed in the text (listed in legend and supplementary table s1). fs: fram strait; wsc: west spitsbergen current; cc: coastal current; esc: east spitsbergen current; egc: east greenland current; af: arctic front; pf: polar front. environmental setting the nordic seas are characterized by three main surface water masses. in the eastern part, the atlantic surface water of the north atlantic current flows northwards. this flow carries heat and salt into the arctic region and helps maintain large ice-free areas year-round and keeps the south-western svalbard climate significantly warmer in wintertime than at comparable latitudes elsewhere in the world (e.g., isachsen et al. 2007; dickson et al. 2008; rhines et al. 2008). the western part of the nordic seas is affected by the east greenland current, which carries cold polar water and sea ice from the arctic ocean southward. the central part is occupied by arctic surface water generated from mixing of the atlantic and polar waters (hop et al. 2006). the cooling of the atlantic water generates cold deep waters, which overflow the greenland–scotland ridge as a cold and dense bottom current. the overflow waters become the main contributor to north atlantic deep water, which represents a vital component in the control of the global thermohaline circulation and climate (van aken 2006). on a regional scale, the hydrographic regime at storfjorden fan is determined by changes in volume and speed of the temperate and saline atlantic water (s > 35; t > 3.0 °c) transported by the west spitsbergen current, the northern extension of the atlantic current and the cooler and less saline arctic surface water (s > 34.3–34.8; t < 0 °c) conveyed by the east spitsbergen current (fig. 1; loeng 1991). a mixture of arctic water and sea ice from the northern barents sea and/or produced in storfjorden is carried northward by the cc, originating from the east spitsbergen current (fig. 1). the density gradients between the two water masses generate the arctic front that defines the maximum sea-ice extent in winter (vinje 1977; loeng 1991). during the spring/summer period, the sea-ice edge usually retreats northwards on the account of melting. atlantic water inflow and sea-ice melting often generate the marginal ice zone, with a stratified and nutrient-rich euphotic zone and high primary productivity at the surface (smith et al. 1987; smith & sakshaug 1990; sakshaug & slagstad 1992; sakshaug 1997; wassmann et al. 1999; owrid et al. 2000; reigstad et al. 2002; tremblay & gagon 2009). during years with strong and cold winds from the north-east, a large volume of brine is produced in the storfjorden polynya (skogseth et al. 2008). storfjorden fan can be influenced by these cold and corrosive brines as they descend the slope to the deep waters (skogseth et al. 2008; rasmussen et al. 2014). material and methods present-day water-mass properties and living planktic foraminifera from plankton tows water column temperature and salinity profiles at the storfjorden fan core site (see later) were measured via an sbe 911plus ctd rosette (seabird scientific) equipped with niskin bottles. ctd measurements took place aboard the rv helmer hanssen on successive cruises in october 2012, july 2014 and april 2015 (fig. 2). fig. 2 (a) ctd profile showing water mass distribution of the water column in october 2012, july 2014 and april 2015 at site hh12-1206bc. carbonate chemistry parameters (ph, co3 2–, ωca) for april 2015 are also shown. range of ωca in the water column is indicated by grey bars. (b) close-up of ctd data in upper 250 m. (c) carbonate ion concentration [co3 2–], ph and calcium carbonate saturation state (ωca) in upper 250 m in april 2015. mmw, mixed meltwater; aw, atlantic water; iw, intermediate water. in april 2015, water samples were collected in the water column for carbonate chemistry (fig. 1a). ct and at were measured at the institute of marine research, tromsø, norway. ct was determined by using coulometric titration on a vindta system and at by using potentiometric titration with weak hcl on a vindta system (marianda, germany). the analytical methods and sampling procedures are described in detail in dickson et al. (2007). the precision of at and ct was determined using certified reference material supplied by a. dickson (san diego, usa) by applying a correction factor to the measured certified reference material value showing an uncertainty of ±1 μmol kg−1 for both at and for ct measurements. the data of ct, at and salinity, temperature and depth for each sample were used in a co2-chemical speciation model (co2sys program; pierrot et al. 2006) to calculate the calcium carbonate saturation state (ωca), ph and the carbonate-ion concentration [co32−]. the calculations were performed on a total hydrogen ion scale using the hydrogen sulphate [hso4−] dissociation constant of dickson (1990). we applied the carbonate system dissolution constants from mehrbach et al. (1973), refit by dickson & millero (1987). the concentration of calcium [ca2+] is assumed to be proportional to the salinity according to the equation 10.28×s/35 μmol kg−1 (mucci 1983). the thermodynamic solubility product constants for calcite (ksp) are from mucci (1983). the ωca value is expressed by the product of concentrations of calcium ions [ca2+] and [co32−] in seawater divided by the solubility product constant (ksp) at a given temperature, salinity and pressure. when ω > 1, caco3 will be kept in solid state, and when ω < 1, caco3 will tend to dissolve. living planktic foraminifera were collected using a wp (working party) 2 plankton tow with 90-μm mesh-size net and 0.255 m2 opening. the plankton tows were deployed immediately after the ctd casts in october 2012 and july 2014 at the core site. in 2012, vertical sampling intervals were 0–50 and 50–200 m, while in 2014, the intervals were 0–50, 50–100 and 100–200 m. concentrations of the foraminifera (number specimens m–3) were calculated based on tow speed and water volume. towing speed was about 0.5 m s−1 and the volume of filtered water was calculated by multiplying the aperture area by depth towed following the general formula: v = πr2 × l, where v = volume (m3) of seawater, π = 3.1415, r2 = radius of net opening squared (m2) and l = length of towing (m). after retrieval, the samples were sieved over sieves of mesh sizes 1000 and 63 μm in the onboard laboratory and fixed with 98% ethanol buffered with disodium hydrogen phosphate to prevent dissolution (size fraction >63 μm only). the samples were stained with rose bengal (1.0 g l−1) in order to differentiate between “living” (shell containing cytoplasm) and “dead/transported” specimens (no cytoplasm present; lutze & altenbach 1991). samples were kept cool until onshore analysis was performed in the laboratory at uit. only living specimens were considered. palaeo-data from sediment core hh12-1206bc a giant box core (50 × 50 × 50 cm with a volume of 125 l) was used to sample sediment from storfjorden fan from 1520-m water depth during a cruise with rv helmer hanssen to the fram strait in october 2012 (76°24′ n; 012°58′ e; fig. 1a). the sediment–water interface was well preserved and undisturbed. a plastic tube of inner diameter 10 cm was pushed into the sediment for subsampling. the 30.5 cm long sediment core labelled hh12-1206bc was sampled in 0.5 cm thick slices in the laboratory at uit. subsequently, all samples were weighed, freeze-dried and weighed again, and the water content (%) was calculated. the dry samples were wet-sieved through mesh-sizes 1 mm, 500 μm, 100 μm and 63 μm following the preparation methods of feyling-hanssen et al. (1971) and knudsen (1998). the residues were dried at room temperature and weighed. grain size distribution was calculated as the weight percentage of each grain-size fraction relative to total dry weight of the sample. ird was counted in the 500–1000 μm and >1000 μm size-fractions and concentrations calculated as number of ird grains per gram dry weight sediment. tc and toc were measured in the intervals of 1–2 cm in powdered bulk samples using a leco cs-200 induction furnace instrument. the weight percentages (wt%) of tc and toc were calculated. the caco3 content (wt%) was calculated using the following equation: caco3 = (tc−toc) × 8.33 (espitalié et al. 1977). planktic foraminiferal specimens (>300) from the size-fraction 100–500 μm were picked from all the 0.5-cm-thick samples, 62 in total. the majority of samples were split, and specimens were counted and identified to species level using a binocular microscope (leica mz16). the concentration was calculated as number of foraminifera per gram dry-weight sediment, and the flux of planktic foraminiferal specimens (number of specimens cm−2 ky−1) was calculated using the methods described by ehrmann & thiede (1985). transfer functions, based on the census data of the planktic foraminiferal species, were used to reconstruct ssts at 10-m water depth and to compare to mg/ca-based subsurface temperatures (see later). the statistical method compares modern oceanographic data (here summer sst) with the species composition of the planktic foraminiferal faunas in the >100-μm size-fraction from surface sediments collected in the nordic seas (husum & hald 2012). the data were processed using the data analysis programme c2 version 1.3 (juggins 2010). the maximum estimate had the lowest root mean square error of prediction, indicative for the most predictive transfer function model (telford & birks 2005). this is confirmed as the maximum-likelihood-calculated ssts are close to the modern water temperature ranges of the core site and follow the actual fluctuations in species composition of the planktic foraminiferal faunas. shell weights of ca. 20–30 pristine and well-preserved tests of planktic foraminiferal species n. pachyderma and t. quinqueloba from two narrow size ranges of 100–125 μm and 150–180 μm were measured using a sartorius microbalance (model m2p, 0.1 μg sensitivity). specimens with sediment fill or visually detectable secondary calcite crust were omitted. mean shell weights were calculated by dividing the total weight of the individuals by the number of total shells within each size range. because of the low abundance of t. quinqueloba, 16 samples from the 100–125-μm size-fraction and 15 samples from the 150–180-μm size-fraction contained less than 10 individuals. all measurements were repeated three times. shell fragments were counted in the >100-μm size-fraction along with the counts of the whole planktic specimens as an indication for the general preservation state of specimens and species (berger 1970; berger et al. 1982). the %fragmentation was calculated relative to the total number of planktic foraminifera per gram and the total number of fragments per gram in a sample. activity profiles of 210pb and 137cs were analysed in the top 12 samples (upper 6.5 cm) in order to determine the modern sr, assess the recovery of core top sediments and establish the age of the youngest sediments. freeze-dried and homogenized samples were analysed at the centre d’études nordiques at the université laval (canada) using a high-resolution germanium diode gamma detector and multichannel analyser gamma counter. prior to analysis, the samples were put into plastic vials to rest for at least three weeks to attain the secular equilibrium. the linear apparent sr was calculated from the decrease of excess 210pb activities with sediment depth following mckee et al. (1983). excess 210pb activity was determined by subtracting the average supported activity (average of 214pb, 214bi and 226ra) from the total activity for each sample. the calculations were based on the constant initial concentration model (for review, see, e.g., carroll & lerche [2003]) that assumes that the 210pb excess concentration in surface sediments is constant over time and the 210pb excess flux to the surface of the sediments together with the sr are proportionally variable. the assumption of a closed system in this model imposes that the 210pb excess activity profile shall decrease exponentially with depth. the sr was determined using the following equation: where λ is the 210pb disintegration constant (=0.03118 yr−1), z is a depth in a core (cm), a0 is the 210pb excess concentration at the surface (below the mixing layer) and az is the 210pb excess concentration at depth z (bottom layer of the interval). the 210pb-derived sr was corroborated by the first occurrence of 137cs as a marker of the early 1950s (robbins & edgington 1975). ams 14c ages were performed at the poznań radiocarbon laboratory, poland, on nine monospecific samples of n. pachyderma, except for two samples at 4.5–6.5 cm and 13–14 cm, where all available planktic foraminifera were picked (table 1). all samples were picked from the 100–500-μm size fraction. the dates were calibrated into calendar ages using the calibration program calib rev. 7.0.2 (stuiver & reimer 1993) and the marine13 calibration curve (reimer et al. 2013). a global average marine reservoir age of 400 radiocarbon years and 7 ± 11 14c years of local deviation (δr) was applied (mangerud et al. 2006). this deviation may vary in time but is unknown for our study area. the sample from 2.0–3.5-cm core depth gave a post-1950 age and most likely contained modern, post-a-bomb carbon. age reversals occurred in samples at 4.5–6.5 cm and at 9.5–11.5 cm (table 1). this could be a sign of mixing of sediment due to re-deposition events or, more likely, an error associated with the very small amount of material (0.08–0.1 mgc) analysed (table 1). the aforementioned three dates were not used in the construction of the age model (see later). the calibrated ages are reported as years ad with a 2σ standard error. table 1 ams 14c and calibrated dates in core hh12-1206bc. lab no. depth (cm) weight (mgc) age 14c bpa calibrated year bpb δ13c age adc midpoint ad ±2σ errors poz-59603 2–3.5 0.12 520 ± 80 d 1–279 –3.9 1671–1949 1810±139 poz-102419 4.5–6.5 0.1 460 ± 40 d 160–198 –22.6 1752–1790 1771±19 poz-57342 9.5–11.5 0.8 900 ± 80 d 357–644 –16.2 1306–1593 1450±144 poz-102418 13–14 0.31 580 ± 35 94–292 –4.1 1658–1856 1757±99 poz-66095 14–16 0.14 830 ± 110 258–634 –14.6 1316–1692 1504±188 poz-59605 19–20 0.48 1175 ± 30 652–779 0.3 1171–1298 1234±63 poz-102417 22–22.5 0.35 1515 ± 30 966–1158 –2.6 792–984 888±96 poz-66211 23.5–25 0.19 1870 ± 70 1272–1560 –17.6 390–678 534±144 poz-57343 30–31 0.12 2320 ± 80 1724–2132 –4.3 183 bc–226 21±205 aradiocarbon years before the present (1950 ad). byears before the calendar year 1950. cexcept the last value in the column, which is 183 bc to 226 ad. ddate not used in age model. elemental ratios of mg/ca (for palaeo-temperature) and al/ca (for control of potential clay contamination) were measured on 60–130 specimens per sample of n. pachyderma (0.5–2 cm resolution). well-preserved, pristine shells were picked from the 150–180-μm size-fraction, crushed and cleaned in the clean laboratory at the alfred wegener institute in bremerhaven, principally following the protocol of barker et al. (2003). the procedure included four steps: (1) clay removal with boron-free milli-q water and methanol, (2) oxidation of organic matter in naoh-buffered h2o2, (3) weak acid leach in 0.001 n hno3 and (4) carbonate dissolution in 60 μl of 1 n hno3. subsequently, an aliquot of 5 μl from each sample was diluted with 200 μl of 2% hno3 to determine the ca concentration. the remaining residue was diluted with 2% hno3 to obtain a ca concentration of 15–20 ppm. the samples were analysed using a nu attom high-resolution double-focusing inductively coupled plasma mass spectrometer at the alfred wegener institute. since the sample material was very limited and to avoid matrix effects in the plasma, analyses were conducted at a ca concentration of about 15 ppm. five replications were carried out for each sample, where the average repeatability for mg/ca among the five replicates was 0.95 ± 0.47% (relative standard deviation). for this study, the measurement uncertainty was determined by analysing the carbonate standard jct-1 (giant clam), yielding mg/ca ratios of 1.28 ± 0.05 (2σ) mmol mol−1, which is within 1% of the values reported in the literature (inoue et al. 2004; hathorne et al. 2013). in addition, long-term reproducibility of mg/ca analyses is monitored by regular analysis of the carbonate standard jcp-1, yielding 3.94 ± 0.15 (2σ) mmol mol−1 over a period of about two years. the measured mg/ca ratios were used to calculate temperatures (sstmg/ca) by using the species-specific (n. pachyderma) linear equation of kozdon et al. (2009): where this calibration is based on core-top samples of n. pachyderma from the nordic seas and produces reliable sstmg/ca estimates at temperatures above about 3 °c (kozdon et al. 2009). stable isotopes were measured on three planktic foraminiferal species: n. pachyderma, t. quinqueloba and globigerinita uvula. these species were chosen as representatives for the surface conditions (g. uvula, average living depth of 15 m [parker 1962; rebotim et al. 2017]), near-surface conditions (t. quinqueloba, not deeper than 50 ± 25 m [simstich et al. 2003]) and subsurface conditions (n. pachyderma, 100–250-m water depth [bauch et al. 1997; simstich et al. 2003; pados & spielhagen 2014]); see “discussion” section. measurements were performed at the leibniz laboratory for radiometric dating and stable isotope research in kiel, on size-fractions 125–150 μm (n. pachyderma), 150–180 μm (t. quinqueloba) and 100–150 μm (g. uvula). results refer to the v-pdb standard. the external analytical reproducibility was <0.06‰ and <0.03‰ for δ18o and δ13c, respectively. measurements on all three species were carried out at 0.5–2-cm intervals. between 7and 10-cm core depth, t. quinqueloba and g. uvula were absent and could not be analysed. palaeo subsurface δ18owater vs. v-smow was calculated based on the mg/careconstructed ssts (see earlier) in conjunction with the following equation (shackleton 1974): where δ18owater is the standard v-smow. conversion from the smow scale to calcite on the v-pdb scale was done by subtracting 0.2‰ (shackleton 1974). results temperature, salinity and carbonate chemistry of the study area the ctd data from april show the coldest surface temperatures of 4.1–4.7 °c and the lowest salinity (fig. 2a, b). the ctd data from july show the presence of a mixed layer ca. 50 m in thickness with meltwater characterized by low salinity and relatively high temperatures of 5.4–7.9 °c. the surface meltwater layer in october shows the highest temperature of 6.3 °c (fig. 2a, b). below the meltwater and surface mixed layer from about 50-m to 500–600-m water depth, a thick layer of warm and saline atlantic water is defined by temperatures ranging from 2.2–4.7 °c in april to 5.4 °c in july and from 1.5 °c to 6.3 °c in october (fig. 2a, b). below the atlantic water layer, cold intermediate waters (t < 0 °c) generated by convection in the nordic seas are found (e.g., blindheim et al. 2000). the upper 200 m are well saturated with ωca, ranging from 2.80 at the surface to 2.66 near 200-m water depth (fig. 2a, c). the carbonate ion concentration [co32−] and ph show a decrease from the surface to 200-m water depth (fig. 2a, c). in both july 2014 and october 2012, maximum absolute abundances of planktic foraminifera are found at 0–50-m water depth, the water layer that represents near-surface to surface water (supplementary fig. s1a, b). in july 2014, the lowest abundance is observed at 50–100-m water depth, while relatively high abundances are recorded at 100–200-m water depth, which is occupied by atlantic water (supplementary fig. s1a). sediment core hh12-1206bc construction of the age model and srs the age model and the srs are constructed based on the 210pb and 137cs activity profiles and the ams 14c ages. because of the reversed 14c dates within the interval 6.5–ca. 11.5 cm, only six ams 14c ages are used in the age model (table 1, fig. 3b). the age model indicates that the core spans the time period from ca. 21 to ca. 2012 ad (fig. 3b). a constant sr between the dated levels is assumed. the mean sr is about 16 cm ky−1 (fig. 3b). minimum rates of about 6 cm occur between ca. 1420 and ca. 1060 ad, while maximum rates of about 53 cm ky−1 occur in the upper part (ca. 1960 ad–present). the period from ca. 1800 to ca. 1950 ad is considered to contain potential re-deposition events and is therefore interpreted with great caution. fig. 3 age model based on 210pb, 137cs and ams 14c datings in core hh12-1206bc. (a) total and excess 210pb activity profiles and 137cs activity profile. (b) age–depth plot of calibrated ams 14c datings. in (a), horizontal bars mark 2σ uncertainties. in (b), dates and diamonds in red indicate calibrated radiocarbon ages, and error bars of ams dates indicated by grey-lined field represent 2σ standard deviation. dark blue diamonds indicate the age model based on 210pb activity. the errors in this age model increase with depth (from 0.3 years at 0.25 cm to 7 years at 5.75 cm, not shown). the light blue areas in (a) and (b) represent a mixing of sediment in the upper 3 cm indicated by 210pb activity profiles. in (b), the grey area shows intervals of reversed 14c dates. sr is shown at the bottom of (b). because chronology with the 14c method over the last 70 years or so is problematic on the account of variations in the 14c input caused by nuclear bomb testing, the short-lived 210pb and 137cs radionuclide-based srs for the core top sediments have been estimated. even though a reliable chronology over the last seven decades cannot be obtained using 14c, an agreement between the long-term srs and short-term srs is useful in the interpretation of the 210pb profiles (half-life: 22.3 years) by extrapolation to longer timescales. in core hh12-1206bc, the 210pb and 137cs activity profiles show a typical decrease with the depth to 6.25 cm. the 3-cm-thick surface layer has the highest and near-uniform activities, indicating sediment mixing and the presence of an upper surface mixed layer, which suggests that the box core recovered an undisturbed sediment surface. from 3.25 cm, 210pb activities decrease exponentially down to 6.25 cm of the core. the average apparent sr is 80 cm ky−1 with a maximum of 100 cm ky−1 (fig. 3a). the three major peaks in 137cs activity related to the atmospheric nuclear bomb testing in the 1950s to mid-70s, and the chernobyl reactor explosion in 1986 (kunzendorf & larsen 2002), have been recorded in marine sediments of the north atlantic and the barents sea (e.g., grøttheim 1999). these peaks are absent in core hh12-1206bc, further supporting the interpretation that the upper 3 cm is a mixed layer. including the approximately 3 cm thick mixed surface layer, the average sr based on 137cs activity becomes 70 cm ky−1 (fig. 3a), which is placed between the 14c-derived value of ca. 53 cm ky−1 and the 210pb-derived value of 80 cm ky−1. sediment composition the sediment is dominated by clay and silt (61–96%), with generally low sand content. a small increase in sand content occurs towards the top of the core (supplementary fig. s2a). the concentration of ird > 1000 μm and 500–1000 μm is generally low. the ird 500–1000 μm increases towards the top of the core (supplementary fig. s2b). the %toc and %tc are low and nearly constant throughout the entire record (supplementary fig. s2c). the %caco3 shows a slight decrease towards the core top reaching a low value of about 10% at 3-cm sediment depth and returning to values of 20–22% afterwards (supplementary fig. s2c). stable isotopes the δ18o values of n. pachyderma and t. quinqueloba generally show an increasing trend with lower δ18o values from about 1800 ad (fig. 4a–c). the record of t. quinqueloba is more variable than the record of n. pachyderma. the δ18o values of g. uvula show the opposite trend of the other two species, but of lower amplitude. the δ13c values of n. pachyderma, t. quinqueloba and g. uvula show similar trends until about 1800 ad (fig. 4d–f). the δ13c values of g. uvula are low between about 400 ad and about 1770 ad but are otherwise high. fig. 4 stable isotope (thin lines represent raw data and thick lines represent 3-point moving average) records in core hh12-1206bc. (a) δ18o, (d) δ13c of neogloboquadrina pachyderma, (b, e) turborotalita quinqueloba and (c, f) globigerinita uvula. planktic foraminifera and recent planktic foraminifera in the study area the plankton tow data were collected in two different years, at different seasons and depth intervals (supplementary fig. s1; see methods section). for better comparison between the relative distributions of species observed in the sediment record versus the water column, we combined all the planktic foraminiferal specimens found in the plankton tow samples to represent the entire upper 200 m of the water column in the two respective years. the living planktic foraminifera are dominated by t. quinqueloba (>80%) in both years of collection, with >10% of living n. pachyderma, <4% g. uvula and <1% n. incompta (fig. 5g, h). in the sediment surface sample (which, according to our age model, represents nine years of annual foraminiferal production), the difference in relative abundances of t. quinqueloba and n. pachyderma is only 10%, while g. uvula represents 20% of the planktic foraminiferal fauna (fig. 5f). fig. 5 planktic foraminiferal distribution data of core hh12-1206bc (a–e): relative abundance (line) and flux (shaded area; number of specimens cm–2 ky–1) of (a) neogloboquadrina pachyderma, (b) turborotalita quinqueloba, (c) globigerinita uvula, (d) neogloboquadrina incompta and (e) total flux and concentration (number of specimens per gram dry weight sediment) of planktic foraminifera. modern data (f–h): (f) relative abundances of planktic foraminiferal species in surface sediment sample (5 mm corresponds to nine years of deposition according to age model), (g, h) relative abundances of living specimens of n. pachyderma (blue), t. quinqueloba (orange), g. uvula (green) and n. incompta (purple) collected in (g) 2012 and (h) 2014 at the coring site. note differences in scale for live and fossil percentages. the fossil planktic foraminiferal assemblages in core hh12-1206bc are dominated by n. pachyderma (33–88%). t. quinqueloba, the second most abundant species, constitutes 9–43% (fig. 5a, b). the third most abundant species is g. uvula (2–20%), which has recently been found in increasing proportions at the western barents sea margin constituting up to 64% of the planktic foraminiferal assemblages (hulot 2015; fig. 5c). other species present are neogloboquadrina incompta (fig. 5d), globigerinita glutinata and globigerina bulloides (the last two are not shown as they are always <1%). the most marked changes in species distribution patterns occur in the last 200 years or so (fig. 5a–e). the mean shell-weights of both size fractions 100–125 μm and 150–180 μm of n. pachyderma and t. quinqueloba show similar and relatively low variability. the highest shell weights are recorded at about 180–340 ad, 1100–1350 ad and 1500–1770 ad (supplementary fig. s2d, fig. 6f). the percentage of shell fragmentation in the entire record is rather low except for short-lasting intervals of high fragmentation at approximately 140 ad, 1600 ad and 1770 ad to the present (fig. 6e). fig. 6 reconstructed late holocene oceanography at storfjorden fan in core hh12-1206bc. (a) mg/ca-ratio-based sst on neogloboquadrina pachyderma representing subsurface temperatures (see text for explanation), (b) subsurface δ18owater, (c) δδ18onp-tq as an indicator of increased/decreased presence of warm atlantic water versus polar water, (d) sum of flux (number of specimens cm–2 ky–1) and concentrations (number of specimens per gram) of n. pachyderma and n. incompta as an indicator for subsurface productivity, (e) %fragmentation, (f) 3-point running average of mean shell weight of n. pachyderma (150–180 μm), (g) sum of flux and concentrations of t. quinqueloba and g. uvula as an indicator for near-surface to surface productivity, (h, right) transfer-function based ssttf at 10-m water depth representing ssts (red line) and (left) instrumental record of global temperature anomaly (black line; berkeley earth 2019) and (i) ird >500 μm (number of mineral grains per gram). vertical pink bars mark warmer time intervals. aw: atlantic water. sst records ssts based on mg/ca ratios (sstmg/ca) vary between 3.1 and 6.2 °c (fig. 6a). these temperatures are very similar to the temperatures (3.9–5.4 °c) recorded at 100–250-m water depth by the three ctd casts (fig. 2a, b). the ssts obtained by transfer functions (ssttf) range between 2.0 and 7.0 °c (fig. 6h). the highest temperatures in this record are found over the last 50 years and fairly closely follow the instrumental record of global temperature anomalies (fig. 6h). discussion interpretation of environmental conditions at storfjorden fan 21–2014 ad based on the modern main depth habitats of the three dominating species, we interpret the living depths for t. quinqueloba (e.g., hemleben et al. 1989; carstens et al. 1997; simstich et al. 2003; sarnthein & werner 2017) and g. uvula (e.g., boltovskoy et al. 1996; hulot 2015; rebotim et al. 2017; schiebel et al. 2017; h. bauch, unpubl. data) as indicators of near-surface to surface water conditions and productivity, respectively (75–ca. 0 m). neogloboquadrina pachyderma and n. incompta, which in fram strait prefer mainly atlantic water, are interpreted as indicators of subsurface water conditions and productivity at depths of about 250–75 m (e.g., bé & tolderlund 1971; johannessen et al. 1994; volkmann & mensch 2001; simstich et al. 2003; pados & spielhagen 2014; pados et al. 2015; sarnthein & werner 2017). furthermore, we associate the ssttf estimated for 10-m water depth and the sstmg/ca based on n. pachyderma with surface and subsurface water temperatures, respectively. in addition, small/large differences in δδ18onp-tq are interpreted as an indication of relative increased/decreased presence of warm and salty atlantic water in the subsurface to near-surface water (moffa-sanchez & hall 2017). local climate and sea-surface conditions high relative abundance and concentration of the subpolar species t. quinqueloba from at about 21 ad indicate the influence of the warm and saline atlantic water (volkmann 2000). the sst estimates representing the subsurface (sstmg/ca) and the surface (ssttf) unanimously confirm the presence of warm and saline water (fig. 6a, h). at roughly 200–400 ad, high sst and increased salinity (δ18owater) indicate that the influence of atlantic water was at its strongest (fig. 6a, b, h). also, the elevated δδ18onp-tq indicates increased presence of atlantic water at the subsurface to near-surface (fig. 6c). the timing indicates an overlap with the later phase of the so-called roman warm period (ca. 200 bc–400 ad), described from north-western europe (e.g., lamb 1977; grove 2004); these warmer conditions at the svalbard margin may have been a local expression of this climatic event (fig. 6). after about 400 ad, the flux of the planktic foraminifera and the percentages and concentrations of t. quinqueloba and g. uvula decreased and became low (fig. 5b, c, e). together with the dominance of the polar species n. pachyderma, this indicates a change towards cold oceanic conditions, at least at the near-surface to surface layer. the sstmg/ca and the ssttf show a ca. 1 °c drop in temperature of the subsurface and surface water, compared to before 400 ad (fig. 6a, h). the low δδ18onp-tq suggests reduced influence of atlantic water in the subsurface to near-surface layers (fig. 6c). a change to warm surface conditions is indicated by a decrease in the relative abundance of the polar species n. pachyderma and a high percentage of subpolar species from ca. 900 ad (fig. 5a–d). between ca. 900 and 1400 ad, the average ssttf was about 5.9 °c (fig. 6h). from about 930 ad, the subsurface water warmed, culminating at about 1250 ad, when the highest subsurface temperatures and salinity over the entire 2000 years, as indicated by the sstmg/ca and δ18owater, occurred (fig. 6a, b). also, the high δδ18onp-tq points to increased presence of atlantic water at this time (fig. 6c). all the proxies clearly suggest a dominance of atlantic water and warm sea-surface conditions lasting until about 1400 ad. the warming and ameliorated conditions potentially represent a local expression of the well-known medieval climate anomaly recorded in north-western europe (ca. 900–1400 ad; e.g., lamb 1977; grove 2004; fig. 6). between about 1400 and 1500 ad, fairly high-magnitude changes in most proxies suggest unstable subsurface to surface water conditions (figs. 5, 6). shifts in all reconstructed ssts, δ18o and δ13c values and a relatively high, but gradually decreasing flux of planktic foraminifera in addition to the dominance of the polar species n. pachyderma point to a progressive trend towards cold conditions with meltwater at the surface and the presence of the marginal ice zone (figs. 4, 5a–e, 6a, h). this was probably caused by an increase in sea-ice cover during winters, initiated by the transition to the cooler sea-surface conditions. the following time interval at ca. 1500–1770 ad is characterized by slightly ameliorated conditions indicated by low percentages of n. pachyderma and relatively high percentages of t. quinqueloba and g. uvula, with relatively high ssttf showing intermediate warm surface waters (figs. 5a–c, 6h). at about 1770 ad, the ssttf indicates a rapid drop and the following interval, at about 1770–1850 ad, is characterized by the lowest ssttf of the past two millennia (fig. 6h). between ca. 1770 and ca. 1850 ad, a shift to very low foraminiferal concentration dominated by n. pachyderma (up to 88%) and with very low mean shell weights, high %fragmentation and markedly increased ird concentrations indicate a change to harsh ocean conditions in winters and expansion of the marginal ice zone, with enhanced sea ice and iceberg rafting during summers (figs. 5a–e, 6e, f, i). together with the minimum of surface ocean temperatures indicated by our reconstructed sst (ssttf ca. 2 °c at ca. 1850 ad and sstmg/ca ca. 3.3 °c at about 1500 ad; fig. 6a, h), the period of roughly 1400–1850 ad has been a local expression of the well-known cold event in northern europe: the little ice age, which occurred at about 1400–1850 ad (e.g., lamb 1977; grove 2004). during the last ca. 200 years, the relative abundance of the cold species n. pachyderma decreased to the minimum of the entire record (fig. 5a). this trend seems to have continued until 2014, as indicated by the relative abundances of the three species recorded by plankton tows (fig. 5g, h). together with high δδ18onp-tq, which indicates an increased presence of atlantic water, and high ssttf, this clearly points to the sea-surface conditions during the last century experiencing a warming (fig. 6c, h). the increased ird indicates more sea ice/icebergs after 1850 ad (fig. 6i). the increasing ssttf at storfjorden fan correlates with increasing global temperatures measured by instrumental records and representing a global warming signal (fig. 6h; berkeley earth 2019). while the surface temperature of the past 60 years has reached a maximum of ca. 7 °c (average 5.4 °c), as indicated by ssttf, the temperatures of the subsurface water have increased only slightly, as indicated by sstmg/ca (fig. 6a, h). palaeoproductivity the high concentration of planktic foraminifera in seasonally sea-ice-covered areas, such as the storfjorden fan area, is related to the presence of the marginal ice zone and its high primary production. the conditions of the sea-ice margin promote higher production of the diatoms that are considered the major food source for such species as n. pachyderma, t. quinqueloba and n. incompta (hemleben et al. 1989). neogloboquadrina pachyderma has been classified as a deep-dwelling subsurface species (see earlier) that calcifies around 200-m water depth (volkmann & mensch 2001; simstich et al. 2003; sarnthein & werner 2017), and n. incompta is a temperate water species that in the nordic seas prefers warm atlantic water (e.g., bé & tolderlund 1971). therefore, we link increased subsurface productivity to high fluxes and concentrations of n. pachyderma and n. incompta. similarly, high fluxes and concentrations of t. quinqueloba and g. uvula are interpreted as increased surface to near-surface productivity. at storfjorden fan, the subsurface and surface to near-surface productivity of planktic foraminifera show a generally concurrent response to the climatic and oceanographic development, with higher productivity influenced by atlantic water (fig. 6). very high, but variable, planktic foraminiferal fluxes and concentrations indicate highest productivity at ca. 1300–1500 ad, 1750–1860 ad and over the last 50 years (fig. 6d, g). these periods with enhanced planktic foraminiferal fluxes likely represent either an approach or a retreat of the productive marginal ice zone occurring during the transitional phases between warm to cold and cold to warm conditions. seasonally, stable and stratified surface water conditions created by sea-ice melting within the marginal ice zone favour phytoplankton blooms leading to increased abundances and subsequent high fluxes of planktic foraminifera (alexander 1980; smith et al. 1987; williams 1993). the minimum productivity of the past 2000 is recorded during the cold period between about 1500 and 1770 ad (fig. 6d, g). this was probably due to harsh sea-ice-covered winters, and summers packed with sea ice and limited food availability. light limitations hinder diatoms and other algae usually from growing intensely under permanent ice cover (e.g., michel et al. 1988; cota & sullivan 1990; gosselin et al. 1990). these productivity changes are confirmed by δ13c values measured on n. pachyderma, t. quinqueloba and g. uvula (fig. 4d–f). changes in δ13c values can be attributed to changes in palaeoproductivity and ventilation of surface and near-surface waters (duplessy 1978) if other chemical, biological and physical factors can be ruled out (e.g., spero et al. 1997; bemis et al. 2000; peeters et al. 2002). the fairly similar general trends in δ13c until ca. 1800 ad in the three species are therefore probably related to similar productivity and ventilation levels in the upper ca. 250 m of the water column (fig. 4d–f). high δ13c values correlate with the maxima in planktic fluxes and low values with the minima. during the last roughly 200 years, the δ13c values in the three species deviated. the δ13c values of n. pachyderma and t. quinqueloba decreased, whereas the δ13c values of g. uvula increased, suggesting decoupling of the productivity and ventilation in the surface waters from the waters below, which may be an indication of stratification near the surface. preservation and carbonate chemistry similar and relatively low variability of mean shell weights of both size fractions 100–125 and 150–180 μm of n. pachyderma and t. quinqueloba indicate a parallel response to environmental changes and preservation of the two species (supplementary fig. s2d). this is confirmed by rather low %fragmentation that generally shows an opposite pattern to the mean shell-weight record, that is, high %fragmentation corresponds to low shell weight of planktic foraminifera (supplementary fig. s2d, fig. 6e, f). better preservation appears to correlate with the warmer periods and an increased influence of atlantic water. during the warm time interval of about 21–400 ad, the mean shell weights of n. pachyderma and t. quinqueloba peaked at about 200 ad with a maximum of 3.32 μg in n. pachyderma (150–180 μg). similar high mean shell weights at ca. 200 ad likewise indicate good preservation at some 317 km north of our core site (zamelczyk et al. 2013). this can be attributed to a strong influence of calcium carbonate-rich atlantic water (e.g., huber et al. 2000). from about 400 ad during the colder period, the mean shell weights of n. pachyderma and t. quinqueloba decreased together with the shell fragmentation (supplementary fig. s2d, fig. 6e, f). this indicates a deterioration of the calcification conditions for these species rather than dissolution due to diagenetic changes in the sediment. high shell weights and the clearly low fragmentation occurred during the warm period at 900–1400 ad, again indicating good preservation. during the cold period of ca. 1400–1530 ad, the mean shell weight of n. pachyderma first decreased, and at ca. 1520 ad, the %fragmentation was high, indicating rather severe preservation problems also correlating with a peak in ice rafting (figs. 6e, f). this is supported by the ca. 1.3 °c temperature drop in surface water, as indicated by the ssttf (fig. 6h). this may possibly be related to changes in [co32−] and ωca due to more sea-ice and subsequent melting during peak reproduction in the summer months (manno et al. 2012; fransson et al. 2013). around 1530 ad, the mean shellweights increased, whereas the %fragmentation decreased, implying good preservation. this coincides with the slightly ameliorated conditions, with low to moderate presence of atlantic water and increased percentages of t. quinqueloba and g. uvula and relatively high ssttf during this time (see discussion earlier; supplementary fig. s2d, figs. 5b, c, 6c, h). we speculate that the moderate presence of atlantic water with high [co32−] compared with polar water characterized by low [co32−] (chierici et al. 2011; manno et al. 2012), in addition to phytoplankton blooms within the marginal ice zone, provided sufficient calcium carbonate and nutrients for planktic foraminifera to maintain similar calcification rates to those recorded during the warm periods at ca. 21–400 and 900–1400 ad (supplementary fig. s2d). during the last approximately 62 years, the increased sst and enhanced inflow of atlantic water are expected to correlate with an increase in the shell weights of n. pachyderma and t. quinqueloba. however, the mean shell weights show only a slight weight increase and no change in %fragmentation (supplementary fig. s2d, fig. 6e, f). it has been shown that carbonate saturation plays an important role in the calcification of foraminiferal shells (russell et al. 2004; lombard et al. 2010; manno et al. 2012). under low [co32−], shell calcification rates tend to decrease (manno et al. 2012). this could be linked to recent ocean acidification, where an increase in co2 in the ocean leads to a decrease of [co32−] and a lower level of calcium carbonate saturation (e.g., chierici et al. 2011). the saturation of calcite (ωca) of 2.2 ± 0.6 and [co32−] of 107 ± 11 μmol kg-1 recorded in april 2015 at our study site fall within the low range of values characteristic for polar water (fig. 2a, c; chierici et al. 2011). moreover, the cooling of surface water in the west spitsbergen current has resulted in large co2 absorption in the north atlantic, which holds greatest amount of anthropogenic co2 (olsen et al. 2010). however, as these measurements were taken in early spring, the relatively low values represent a season of sea-ice melting, also supported by low salinity and low temperatures (fig. 2a, b). as there is no clear relationship between shell weight, concentration, growth of planktic foraminifera and environmental conditions (e.g., carbonate saturation, temperature, productivity, optimum growth conditions; e.g., weinkauf et al. [2016] and lischka et al. [2018]), it is impossible to determine whether the low mean shell weights result from ocean acidification or other environmental factors. late holocene changes in water-mass properties and productivity: comparison to other studies except for the anthropogenic global warming (e.g., abram et al. 2016), climate variability and its spatiotemporal development during the past two millennia has recently been shown to be regional signal and not a global phenomenon (neukom et al. 2019), aside from a general ocean cooling trend over the last 2000 years (e.g., mcgregor et al. 2015). climatic periods and their timing defined historically in north-western europe by lamb (1977) correlate with major changes in proxy records in the north atlantic and nordic seas region. they indicate temperature and productivity changes on multidecadal to centennial timescales with prominent cold and warm anomalies (e.g., jiang et al. 2002; spielhagen et al. 2011; andresen et al. 2013; matul et al. 2018). increased inflow of warm subsurface atlantic water from the norwegian sea into the arctic ocean via the eastern fram strait is considered to be responsible for the warm intervals associated with the roman warm period, the medieval climate anomaly and the recent warming (spielhagen et al. 2011; werner et al. 2011; zamelczyk et al. 2013; werner et al. 2016). however, depending on the environmental settings, proximity of the sea-ice edge, availability of nutrients, microfossil types and other proxies, the productivity signals may vary considerably (matul et al. 2018; moffa-sánchez et al. 2019). we compare our temperature estimates and flux of the subsurface dwelling n. pachyderma and near-surface to surface living t. quinqueloba and g. uvula as indicators of subsurface and near-surface to surface water productivity, respectively, to other records based on planktic foraminifera and other microfossils indicative of biological production in fram strait and northern north atlantic (figs. 1, 7; supplementary table s1). fig. 7 comparison of oceanic conditions of the last two millennia at storfjorden fan with other records from the eastern fram strait. (a, b) subsurface productivity indicated by the flux of neogloboquadrina pachyderma and n. incompta and subsurface mg/ca-based palaeotemperature in core hh12-1206bc (this study) compared to (c) subsurface transfer function palaeotemperature based on planktic foraminifera at 100-m water depth and (d) subsurface productivity at kveithola trough at the western barents sea margin in core jm09-ka11-gc (berben et al. 2014). near-surface to surface (e, f) temperature at 10-m water depth and productivity indicated by the flux of turborotalita quinqueloba and globigerinita uvula in core hh12-1206bc (this study) compared with (g) the flux of t. quinqueloba and g. uvula in core jm09-ka11gc and (h) concentration of planktic foraminifera in core gik23258. (i, j) mg/ca-based palaeotemperatures measured in n. pachyderma on the western svalbard margin (i) core msm5/5-712-1 (spielhagen et al. 2011) and (j) core msm05/5-712-2 (aagaard-sørensen et al. 2014), (k) flux of n. pachyderma and n. incompta in core jm06-04mc (black line; zamelczyk et al. 2013) and flux of polar planktic foraminiferal species in core msm5/5-712-1 (green line; spielhagen et al. 2011), (l) flux of t. quinqueloba and g. uvula in core jm06-04mc (black line; zamelczyk et al. 2013) and flux of subpolar planktic foraminiferal species in core msm5/5-712-1 (green line; spielhagen et al. 2011), (m) phytoplankton biomarker in core msm5/5-712-1 (cabedo-sanz & belt 2016), (n) ssttf at 50-m water depth in core msm5/5-712-1 (spielhagen et al. 2011) and (o) total planktic foraminiferal flux in core msm5/5-712-1 (werner et al. 2011). vertical pink bars mark warmer time intervals. for list of records with references, refer to supplementary table s1. rwp: roman warm period; dacp: dark ages cold period; mca: medieval climate anomaly; lia: little ice age; rw: recent warming. at storfjorden fan, the beginning of the past two millennia was characterized by a strengthened inflow of atlantic water and relatively warm and productive subsurface and near-surface to surface water. at the same time, an enhanced influence of warm atlantic water and a low relative abundance of n. pachyderma were recorded at a site from the subpolar gyre south of greenland and iceland (moffa-sánchez & hall 2017). in contrast, low surface productivity is indicated by a low flux and concentration of planktic foraminifera from core sites just south of our study area off spitsbergenbanken on the deep slope (core gik23258) and on the nearby shelf (kveithola trough core jm09-ka11gc; sarnthein et al. 2003; berben et al. 2014; fig. 7a–h; supplementary table s1). in core gik23258, a sharp peak in relative abundance of t. quinqueloba occurred at ca. 280 ad, indicating a short-lasting pulse of warm atlantic water advection (sarnthein et al. 2003). the differences in productivity signals between the records from off spitsbergenbanken and storfjorden fan can probably be explained by the position of the sea-ice margin and seasonal variation in the extension of the marginal ice zone. the sea-ice margin was likely located further north along the western svalbard margin, closer to our study site at the time. high planktic foraminiferal flux is reported in core msm5/5-712-2, suggesting highly productive near-surface to surface waters northwest of svalbard (werner et al. 2011; fig. 7o; supplementary table s1). the high surface productivity correlates with a warming of the subsurface water indicated by the sstmg/ca based on n. pachyderma (fig. 7b). moreover, high productivity at the near-surface to surface in this area is also indicated by a high concentration of phytoplankton biomarkers at about 340 ad and high flux of diatoms at ca. 46–455 ad (müller et al. 2012; matul et al. 2018). these conditions are linked to a northward retreat of the sea-ice edge due to strengthened atlantic water inflow and/or changes in the atmospheric circulation pattern (werner et al. 2011; müller et al. 2012; matul et al. 2018). the second warm period at the storfjorden fan is recorded at about 900–1400 ad (fig. 7). warm ssttf occurred at about 800–1100 ad in core jm09-ka11gc from kveithola trough and at about 800–1400 ad in core msm5/5-712-1 from the north-western svalbard margin and has been associated with the medieval climate anomaly (spielhagen et al. 2011; berben et al. 2014; fig. 7c, n; supplementary table s1). the subsurface and near-surface productivity indicated by planktic foraminifera show only a relatively moderate increase at our study site and in other records along the western barents sea and svalbard margin (fig. 7a, d, f, g, o). even in northern storfjorden, where biological production is mainly determined by the extent of the sea-ice cover and solar radiation, a diminished productivity indicated by a reduction in concentrations of phytoplankton biomarkers has been linked to a reduced sea-ice cover (knies et al. 2017). the two cold periods at 400–900 ad and ca. 1400–1850 ad, recorded at storfjorden fan, are also identified on the western svalbard and barents sea margin and have been associated with the dark ages cold period and the little ice age, respectively (werner et al. 2011; berben et al. 2014; werner et al. 2016). they found these intervals to correlate with pronounced changes in the planktic foraminiferal fauna compositions and low planktic foraminiferal flux. the low subsurface and near-surface to surface productivity at storfjorden fan during the cold period at 400–900 ad correspond to low primary productivity and low content of phytoplankton biomarkers recorded in northern storfjorden in core jm10-010gc (pathirana et al. 2015; knies et al. 2017), and low concentrations of benthic foraminifera (rasmussen & thomsen 2015; fig. 7a, f; supplementary table s1). the low productivity is linked to a south-eastward shift of the marginal ice zone associated with extensive sea-ice cover and a reduced inflow of atlantic water from the nordic seas. on the western svalbard margin, high sea-surface salinity indicates enhanced atlantic water influence at about 1600 ad (werner et al. 2011). as the salinity increase was not accompanied by warmer temperatures, these salinity values were considered erroneous. at 1400–ca. 1500 ad, the moderate to high flux of planktic foraminifera agrees with the high surface productivity recorded by a high flux of cold-water dinocyst assemblages in core jm06-04mc from the western svalbard margin (bonnet et al. 2010), but contrasts with a decrease in primary productivity around 1450 ad in the nearby core st20 from the kveithola trough on the shelf (pathirana et al. 2015; fig. 1; supplementary table s1). the interval is referred to as the first half of the little ice age (bonnet et al. 2010; pathirana et al. 2015). we speculate that the differences in productivity between the st20 and our site were caused by a highly fluctuating sea-ice margin, with strong seasonal gradients and intense melting at the sea-ice edge due to influence of the warm atlantic water, as is observed in the western barents sea (e.g., pathirana et al. 2015). the minimum productivity, but relatively warm surface conditions at ca. 1500–1770 ad at storfjorden fan coincided with low fluxes of planktic foraminifera. the warmer conditions are in contrast to the low near-surface temperatures in cores jm06-04mc (zamelczyk et al. 2013) and msm5/5-712-2 (spielhagen et al. 2011; werner et al. 2011) from the western svalbard margin and in core jm09-ka11gc from kveithola trough (berben et al. 2014; fig. 7e–g, k, i, n, o; supplementary table s1). the relatively warm conditions at storfjorden fan correlate with an increased sst estimated from alkenones (uk37) and reduced sea-ice concentration in spring recorded in the same core msm5/5-712-1 from the western svalbard margin (rueda et al. 2013; cabedo-sanz & belt 2016). a rapid and short-lasting ice-edge retreat within the marginal ice zone during springs/summers due to the presence of atlantic water was most likely responsible for the seasonal warm sea-surface conditions. nevertheless, the lowest fluxes of all planktic foraminifera with increasing ird concentration recorded in all compared cores during this time suggest generally enhanced sea-ice cover and harsh sea-surface conditions. the increase in planktic foraminiferal flux from ca. 1770 ad at our study site correlates with the high surface productivity indicated by high concentration of the phythoplankton biomarker brassicasterol from ca. 1750 ad in core msm5/5-712-1 from the western svalbard margin (fig. 7m; supplementary table s1). the high surface productivity has been explained by a change from high seasonal sea-ice cover to a winter ice-edge scenario, with reduced spring sea-ice concentration, at this site (cabedo-sanz & belt 2016). more sea ice and icebergs after 1850 ad, indicated by increased ird at storfjorden fan (fig. 6i), have been associated with the little ice age from 1860 ad in a record from the western svalbard margin (werner et al. 2011). the event is linked to a continuous strengthening of the meridional overturning circulation intensity (sicre et al. 2008) and increased deep water production in the norwegian–greenland sea. studies of planktic and benthic foraminiferal faunas, biomarker and sedimentological reconstructions from the western part of the nordic seas influenced by the egc do not depict any prominent cold and warm anomalies (perner et al. 2015; andrews et al. 2016). at the shallow foster bugt site, north-east greenland shelf in core ps 2641, the surface conditions described by foraminifera indicate an overall cooling and a large and variable input of meltwater from greenland from about 800 ad to the present, with markedly increased productivity over the last millennium (perner et al. 2015; fig. 1a; supplementary table s1). the cooling trend over the past two millennia has been detected further south, at the southern greenland margin in core rapid-35com (moffa-sánchez & hall 2017) and south of iceland in core rapid-17-5p (moffa-sánchez et al. 2014). in rapid-17-5p, an increasing influence of the egc and cold surface conditions were recorded over the last millennium by planktic foraminiferal assemblages and mg/ca-based temperature reconstructions from a deep-dwelling planktic foraminiferal species (moffa-sánchez et al. 2014; fig. 1a; supplementary table s1). south of iceland, in cores rapid-21-3k (sicre et al. 2011) and rapid-17-5p (moffa-sánchez et al. 2014), clear centennial-scale changes in sst have been linked to climatic events such as the warm roman warm period and cold little ice age (fig. 1a; supplementary table s1). north of iceland, apparently subdued temperature variations related to the little ice age and warm medieval climate anomaly were recorded (e.g., knudsen et al. 2004; knudsen et al. 2011). the progressive warming over the last 200 years is considered to be globally synchronous (neukom et al. 2019 and references herein) and well documented in numerous palaeoproxy studies from the arctic region (e.g., kaufman et al. 2009; majewski et al. 2009; spielhagen et al. 2011; werner et al. 2011; dylmer et al. 2013; zamelczyk et al. 2013). some studies consider the last 100 years as the warmest period of the last two millennia (neukom et al. 2019). in fram strait, in core msm5/5-712-1, fluxes and sst based on planktic foraminifera show relatively stable temperatures and productivity for most of the past two millennia, and only a rapid increase in the past 100 years that is argued to represent greater advection of atlantic water into the arctic (spielhagen et al. 2011; fig. 7k, l, n; supplementary table s1). however, the phytoplankton biomarker (brassicasterol) recorded at the same site shows marked variability in productivity throughout the entire studied period (cabedo-sanz & belt 2016; fig. 7m; supplementary table s1). the sst reconstructions based on dinocyst assemblages indicate a cooling trend with a salinity reduction at the same site over the last 2000 years (bonnet et al. 2010). the contrasting trends may reflect a habitat bias in the different proxies or, more likely, a bias due to post-depositional dissolution of planktic foraminifera at this location (zamelczyk et al. 2013; fig. 7k, l; supplementary table s1). at storfjorden fan, the ssttf reconstructions show a distinct warming trend at the near-surface to surface from 1850 ad onwards and surface productivity accompanied the temperature changes at all sites under the influence of warm atlantic water (fig. 7c–f, k–o). although the subsurface sstmg/ca-based temperatures indicate a cooling trend, the productivity at the subsurface increased (fig. 7a, b, k). this can probably be linked to the progressive changes in the net primary production associated with increased temperatures, loss of sea ice and increased phytoplankton production (arrigo & van dijken 2015). conclusions the major climate anomalies of the past two millennia were reflected in planktic foraminiferal records at storfjorden fan, western svalbard margin, based on the distribution, concentration and flux of species, sst reconstructions by mg/ca, transfer functions and δ18o and δ13c values of n. pachyderma, t. quinqueloba and g. uvula. enhanced fluxes of planktic foraminifera, increased but variable percentages of subpolar species and decreased relative abundances of n. pachyderma, along with high mean shell weights, characterized periods at about 21–400 ad, 900–1400 ad and 1850 ad to the present. these periods were linked to a local expression of the northern european climate events, the roman warm period, the medieval climate anomaly and the recent warming, respectively. the highest temperatures of the past two millennia occurred during the last 50 years. oceanic conditions at about 400–900 ad and 1400–1850 ad were cold. they were generally characterized by a very low to low flux of planktic foraminifera, a low to moderate relative abundance of the subpolar species and a dominance of the polar species n. pachyderma. a very low flux of planktic foraminifera, but relative warm ssts, and increased percentages of subpolar species (t. quinqueloba and g. uvula) were observed at about 1500–1770 ad, which we attribute to a short-lasting amelioration due to the seasonal presence of atlantic water. this period was followed by the coldest interval of the past two millennia at approximately 1770–1850 ad, which may be linked to the culmination of the cold climate of the northern european little ice age. the subsurface (250–75 m) and surface to near-surface (75–0 m) productivity of planktic foraminifera show a generally concurrent response to the climatic and oceanographic development. moderate to high fluxes and concentrations of planktic foraminifera characterized warm periods, and low fluxes and concentrations of planktic foraminifera characterized cold periods. the highest planktic productivity indicated by very high, but variable, planktic foraminiferal flux and concentration occurred at about 1300–1500 ad, 1750–1860 ad and over the past 50 years or so. these periods likely represent a general amelioration of conditions from years with sea-ice cover to years with a fluctuating summer ice margin. a close link between the shell weights, the preservation of planktic foraminifera and atlantic water presence during the past 2000 years, except the last 50 years, implies that the main factor controlling the calcification rate of planktic foraminifera is the carbonate chemistry state ([co32–] and ωca) of the atlantic water. our reconstructed ssttf correlates with atmospheric temperatures for the last 162 years, suggesting a high reliability of our sst reconstruction based on the planktic foraminiferal data for the past 2000 years and further confirms that the warming of the last 50 years is a well-established occurrence within fram strait. comparison to other records from the western svalbard margin and western barents sea based on different productivity and climate proxies (planktic foraminifera, dinocysts, alkenones) show temporary inconsistencies. these inconsistencies have been reported previously and can be attributed to the local variability of the sea-ice margin, the response of biological productivity to the variability and the possible habitat and/or preservation biases that each proxy represents. acknowledgements the authors thank the captains and crews of rv jan mayen/helmer hanssen and engineers s. iversen and b.r. olsen for technical assistance. t. dahl is thanked for laboratory assistance and t. grytå for creating the area map. the authors thank b. sternal and w. szczuciński for helpful suggestions and discussions of interpretation of the 210pb and 137cs dating. jessica green corrected the english language. the authors also thank dr elena ivanova, anonymous reviewer #2 and section editor robert spielhagen for their valuable comments, which greatly improved the manuscript. references aagaard-sørensen s., husum k., hald m., marchitto t. & godtliebsen f. 2014. sub sea surface temperatures in the polar north atlantic during the holocene: planktic foraminiferal mg/ca temperature reconstructions. the holocene 24, 93–103, doi: 10.1177/0959683613515730. abram n., mcgregor h., tierney j., evans m.n., mckay n.p., kaufman d.s. & the pages 2k consortium 2016. early onset of industrial-era warming across the oceans and continents. nature 536, 411–418, doi: 10.1038/nature19082. alexander v. 1980. interrelationships between the seasonal sea ice and biological regimes. cold regions science and technology 2, 157–178, doi: 10.1016/0165-232x(80)90072-5. andresen c., hansen m., seidenkrantz m.-s., jennings a., knudsen m., nørgaard-pedersen n., larsen n.k., kuijpers a. & pearce c. 2013. midto late-holocene oceanographic variability on the southeast greenland shelf. the holocene 23, 167–178, doi: 10.1177/0959683612460789. andrews j.t., stein r., moros m. & perner k. 2016. late quaternary changes in sediment composition on the ne greenland margin (~73° n) with a focus on the fjords and shelf. boreas 45, 381–397, doi: 10.1111/bor.12169. arrigo k.r. & van dijken g.l. 2015. continued increases in arctic ocean primary production. progress in oceanography 136, 60–70, doi: 10.1016/j.pocean.2015.05.002. barker s., greaves m. & elderfield h. 2003. a study of cleaning procedures used for foraminiferal mg/ca paleothermometry. geochemistry, geophysics, geosystems 4, article no. 8407, doi: 10.1029/2003gc000559. bauch d., carsens j. & wefer g. 1997. oxygen isotope composition of living neogloboquadrina pachyderma (sin.) in the arctic ocean. earth and planetary science letters 146, 47–58, doi: 10.1016/s0012-821x(96)00211-7. bé a.h.w. & tolderlund d.s. 1971. distribution and ecology of living planktonic foraminifera in surface waters of the atlantic and indian oceans. in b.m. funnell & w.r. riedel (eds.): the micropaleontology of the oceans. pp. 105–149. cambridge: cambridge university press. bemis b.e., spero h.j., lea d.w. & bijma j. 2000. temperature influence on the carbon isotopic composition of globigerina bulloides and orbulina universa (planktonic foraminifera). marine micropaleontology 38, 213–228, doi: 10.1016/s0377-8398(00)00006-2. berben s.m.p., husum k., cabedo-sanz p. & belt s.t. 2014. holocene sub-centennial evolution of atlantic water inflow and sea ice distribution in the western barents sea. climate of the past 10, 181–198, doi: 10.5194/cp-10-181-2014. berben s.m.p., husum k., navarro-rodriguez a., belt s.t. & aagard-sørensen s. 2017. semi-quantitative reconstruction of early to late holocene spring and summer sea ice conditions in the northern barents sea. journal of quaternary science 32, 587–603, doi: 10.1002/jqs.2953. berger w.h. 1970. planktonic foraminifera-selective solution and the lysocline. marine geology 8, 111–138, doi: 10.1016/0025-3227(70)90001-0. berger w.h., bonneau m.c. & parker f.l. 1982. foraminifera on the deep-sea floor: lysocline and dissolution rate. oceanologia acta 5, 249–258. berkeley earth. 2019. land and ocean summary, land + ocean data. accessed on the internet at http://berkeleyearth.org/archive/land-and-ocean-data/#section-0-7 on 1 june 2019. beszczynska-möller a., fahrbach e., schauer u. & hansen e. 2012. variability in atlantic water temperature and transport at the entrance to the arctic ocean, 1997–2010. ices journal of marine science 69, 852–863, doi: 10.1093/icesjms/fss056. blindheim j., borovkov v., hansen b., malmberg s.a, turrell w.r. & østerhus s. 2000. upper layer cooling and freshening in the norwegian sea in relation to atmospheric forcing. deep-sea research part i 47, 655–680, doi: 10.1016/s0967-0637(99)00070-9. boltovskoy e., boltovskoy d., correa n. & brandini f. 1996. planktic foraminifera from the southwestern atlantic (30°–60°s): species-specific patterns in the upper 50 m. marine micropaleontology 28, 53–72, doi: 10.1016/0377-8398(95)00076-3. bonnet s., de vernal a., hillaire-marcel c., radi t. & husum k. 2010. variability of sea surface temperature and sea-ice cover in the fram strait over the last two millennia. marine micropaleontology 74, 59–74, doi: 10.1016/j.marmicro.2009.12.001. cabedo-sanz p. & belt s.t. 2016. seasonal sea ice variability in eastern fram strait over the last 2000 years. arktos 2, article no. 22, doi: 10.1007/s41063-016-0023-2. carroll j. & lerche i. 2003. sedimentary processes: quantification using radionuclides. amsterdam: elsevier. carstens j., hebbeln d. & wefer g. 1997. distribution of planktic foraminifera at the ice margin in the arctic (fram strait). marine micropaleontology 29, 257–269, doi: 10.1016/s0377-8398(96)00014-x. chierici m., fransson a., lansard b., miller l.a., mucci a., shadwick e., thomas h., tremblay j.-e. & papakyriakou t. 2011. the impact of biogeochemical processes and environmental factors on the calcium carbonate saturation state in the circumpolar flaw lead in the amundsen gulf, arctic ocean. journal of geophysical research—oceans 116, c00g09, doi: 10.1029/2011jc007184. conan s.m.h., ivanova e.m. & brummer g.j.a. 2002. quantifying carbonate dissolution and calibration of foraminiferal dissolution indices in the somali basin. marine geology 182, 325–349, doi: 10.1016/s0025-3227(01)00238-9. cota g.f. & sullivan c.w. 1990. photoadaptation, growth and production of bottom ice algae in the antarctic. journal of phycology 26, 399–411, doi: 10.1111/j.0022-3646.1990.00399.x. dickson a.g. 1990. standard potential of the (agcl(s)11/2h2 (g)5ag(s)1hcl(aq)) cell and the dissociation constant of bisulfate ion in synthetic sea water from 273.15 to 318.15 k. journal of chemical thermodynamics 22, 113–127. dickson a.g. & millero f.j. 1987. a comparison of the equilibrium constants for the dissociation of carbonic acid in seawater media. deep sea research 34, 1733–1743, doi: 10.1016/0198-0149(87)90021-5. dickson a.g., sabine c.l. & christian j.r. 2007. guide to best practices for ocean co2 measurements. pices special publication 3. ioccp report 8. sidney, bc: north pacific marine science organization. dickson r.r., meincke j. & rhines p. 2008. a general introduction. in r.r. dickson et al. (eds.): arctic–subarctic ocean fluxes: defining the role of the northern seas in climate. pp. 1–12. dordrecht: springer. duplessy j.-c. 1978. isotope studies. in j. gribbin (ed.): climatic change. pp. 46–67. london: cambridge university press. dylmer c.v., giraudeau j., eynaud f., husum k. & de vernal a. 2013. northward advection of atlantic water in the eastern nordic seas over the last 3000 yr. climate of the past 9, 1505–1518, doi: 10.5194/cp-9-1505-2013. ehrmann w.u. & thiede j. 1985. history of mesozoic and cenozoic sediments fluxes to the north atlantic ocean. stuttgart: e. schweizerbart’sche verlagsbuchhandlung. ellingsen i., dalpadado p., slagstad d. & loeng h. 2008. impact of climatic change on the biological production in the barents sea. climate change 87, 155–175, doi: 10.1007/s10584-007-9369-6. espitalié j., laporte j.l., madec m., marquis f., leplat p., paulet j. & boutefeu a. 1977. méthode rapide de characterisation des roches-mere, de leur potential petrolier et de leur degre d’évolution. (rapid method of characterization of parent rocks, their petroleum potential and their degree of evolution.) revue de l’institute francais du petrole 32, 23–42. feyling-hanssen r.w., jorgensen j.a., knudsen k.l. & anderson a.l. 1971. late quaternary foraminifera from vendsyssel, denmark and sandnes, norway. bulletin of the geological society of denmark 21, 67–317. fransson a., chierici m., miller l.a., carnat g., thomas h., shadwick e., pineault s. & papakyriakou t.m. 2013. impact of sea-ice processes on the carbonate system and ocean acidification state at the ice–water interface of the amundsen gulf, arctic ocean. journal of geophysical research—oceans 118, 7001–7023, doi: 10.1002/2013jc009164. gosselin m., legendre l., therriault j.c. & demers s. 1990. light and nutrient limitation of sea ice microalgae (hudson bay, canadian arctic). journal of phycology 26, 220–232, doi: 10.1111/j.0022-3646.1990.00220.x. grøttheim s. 1999. artificial radionuclides in the northern european marine environment in 1995. distribution of plutonium, americium and radiocaesium in seawater and sediments. cand. scient. thesis, department of biology, section of marine zoology and marine chemistry, university of oslo. grove j.m. 2004. little ice ages: ancient and modern. 2 vols. london: taylor & francis. hathorne e.c., gagnon a., felis t., adkins j., asami r., boer w., caillon n., case d., cobb k.m., douville e., demenocal p., eisenhauer a., garbe‐schönberg d., geibert w., inoue m., kawahata h., kölling m., cornec f.l., linsley b.k., mcgregor h.v., montagna p., nurhati i.s., quinn t.m., raddatz j., rebaubier h., robinson l., sadekov a., sherrell r., sinclair d., tudhope a.w., wei g., wong h., wu h.c. & you c.-f. 2013. interlaboratory study for coral sr/ca and other element/ca ratio measurements. geochemistry, geophysics, geosystems 14, 3730–3750, doi: 10.1002/ggge.20230. hemleben c., spindler m. & anderson o.r. 1989. modern planktonic foraminifera. new york: springer. hoff u., rasmussen t.l., stein r.m., ezat m. & fahl k. 2016. sea ice and millennial-scale climate variability in the nordic seas 90 ka to present. nature communication 7, article no. 12247, doi: 10.1038/ncomms12247. hop h., falk-petersen s., svendsen h., kwaśniewski s., pavlov v., pavlova o. & søreide j.e. 2006. physical and biological characteristics of the pelagic system across fram strait to kongsfjorden. progress in oceanography 71, 182–231, doi: 10.1016/j.pocean.2006.09.007. huber r., meggers h., baumann k.h. & henrich r. 2000. recent and pleistocene carbonate dissolution in sediments of the norwegian–greenland sea. marine geology 165, 123–136, doi: 10.1016/s0025-3227(99)00138-3. hulot v. 2015. variabilité spatiale et structurelle des communautés du phytoplancton et de foraminifères planctoniques à l’entrée de la mer de barents. (spatial and structural variability of phytoplankton and planktonic foraminifera communities at the entrance to the barents sea.) msc thesis, université de bretagne occidentale. husum k. & hald m. 2012. arctic planktic foraminiferal assemblages: implications for subsurface temperature reconstructions. marine micropaleontology 96–97, 38–47, doi: 10.1016/j.marmicro.2012.07.001. imbrie j. & kipp n.g. 1971. a new micropaleontological method for quantitative paleoclimatology: application to a late pleistocene caribbean core. in k.k. turekian (ed.): late cenozoic glacial ages. pp. 71–147. new haven, ct: yale university press. inoue m., nohara m., okai t., suzuki a. & kawahata h. 2004. concentrations of trace elements in carbonate reference materials coral jcp‐1 and giant clam jct‐1 by inductively plasma-mass spectrometry. geostandards and geoanalytical research 28, 411–416, doi: 10.1111/j.1751-908x.2004.tb00759.x. isachsen p.e., mauritzen c. & svendsen h. 2007. dense water formation in the nordic seas diagnosed from sea surface buoyancy fluxes. deep-sea research i 54, 22–41, doi: 10.1016/j.dsr.2006.09.008. jiang h., seidenkrantz m.-s., knudsen k.l. & eiriksson j. 2002. late‐holocene summer sea‐surface temperatures based on a diatom record from the north icelandic shelf. holocene 12, 137–147, doi: 10.1191/0959683602hl529rp. johannessen t., jansen e., flatøy a. & ravelo a.c. 1994. the relationship between surface water masses, oceanographic fronts and paleoclimatic proxies in surface sediments of the greenland, iceland, norwegian seas. nato asi series i, 61–86. juggins s. 2010. software for ecological and palaeoecological data analysis and visualization. c2, version 1.6.6. university of newcastle, newcastle upon tyne, uk. kaufman d.s., schneider d.p., mckay n.p., ammann c.m., bradley r.s., briffa k.r., miller g.h., otto-bliesner b.l., overpeck j.t., vinther b.m. & arctic lakes 2k project members 2009. recent warming reverses long-term arctic cooling. science 325, 1236–1239, doi: 10.1126/science.1173983. knies j., pathirana i., cabedo-sanz p., banica a., fabian k, rasmussen t.l., forwick m. & belt s. 2017. sea-ice dynamics in an arctic coastal polynya during the past 6500 years. arktos 3, article no. 1, doi: 10.1007/s41063-016-0027-y. knudsen k.l. 1998. foraminiferer i kvartær stratigrafi: laboratorie og fremstillingsteknik samt udvalgte eksempler. (foraminifera in quaternary stratigraphy: laboratory and preparation techniques as well as selected examples.) geologisk tidsskrift 3, 1–25. knudsen k.l., jiang j., jansen e., eiríksson j., heinemeier j. & seidenkrantz m.-s. 2004. environmental changes off north iceland during the deglaciation and the holocene: foraminifera, diatoms and stable isotopes. marine micropaleontology 50, 273–305, doi: 10.1016/s0377-8398(03)00075-6. knudsen m.f, seidenkrantz m.-s., jacobsen b.h. & kuijpers a. 2011. tracking the atlantic multidecadal oscillation through the last 8,000 years. nature communications 2, article no. 178, doi: 10.1038/ncomms1186. kozdon r., eisenhauer a., weinelt m., meland m.y. & nürnberg d. 2009. reassessing mg/ca temperature calibrations of neogloboquadrina pachyderma (sinistral) using paired δ44/40ca and mg/ca measurements. geochemistry, geophysics, geosystems 10, article no. 3, doi: 10.1029/2008gc002169. kunzendorf h. & larsen b. 2002. a 200–300 year cyclicity in sediment deposition in the gotland basin, baltic sea, as deduced from geochemical evidence. applied geochemistry 17, 29–38, doi: 10.1016/s0883-2927(01)00088-9. lamb h.h. 1977. climate: present, past and future. vol. 2. climatic history and the future. london: methuen. le j.n. & thunell r.c. 1996. modelling planktic foraminiferal assemblage changes and application to sea surface temperature estimation in the western equatorial pacific ocean. marine micropaleontology 28, 211–229, doi: 10.1016/0377-8398(96)00009-6. lischka s., stange p. & riebesell u. 2018. response of pelagic calcifiers (foraminifera, thecosomata) to ocean acidification during oligotrophic and simulated up-welling conditions in the subtropical north atlantic off gran canaria. frontiers in marine science 5, article no. 379, doi: 10.3389/fmars.2018.00379. loeng h. 1991. features of the physical oceanographic conditions of the barents sea. polar research 10, 5–18, doi: 10.3402/polar.v10i1.6723. lombard f., da rocha r.e., bijma j. & gattuso j.-p. 2010. effect of carbonate ion concentration and irradiance on calcification in planktonic foraminifera. biogeoscience 7, 247–255, doi: 10.5194/bg-7-247-2010. lutze g.f. & altenbach a. 1991. technik und signifikanz der lebendfarbung benthischer foraminiferen mit bengalrot. (technique and significance of rose bengal staining benthic foraminifera.) geologisches jahrbuch a 128, 251–265. majewski w., szczuciński w. & zajączkowski m. 2009. interactions of arctic and atlantic water-masses and associated environmental changes during the last millennium, hornsund (sw svalbard). boreas 38, 529–544, doi: 10.1111/j.1502-3885.2009.00091.x. mangerud j., bondevik s., gulliksen s., hufthammer a.k. & høisæter t. 2006. marine 14c reservoir ages for 19th century whales and molluscs from the north atlantic. quaternary science reviews 25, 3228–3245, doi: 10.1016/j.quascirev.2006.03.010. manno c., morata n. & bellerby r. 2012. effect of ocean acidification and temperature increase on the planktonic foraminifer neogloboquadrina pachyderma (sinistral). polar biology 35, 1311–1319, doi: 10.1007/s00300-012-1174-7. matul a., spielhagen f.r, kazarina g., kruglikova s., dmitrenko o. & mohan r. 2018. warm-water events in the eastern fram strait during the last 2000 years as revealed by different microfossil groups. polar research 37, article no. 1540243, doi: 10.1080/17518369.2018.1540243. mcgregor h.v., evans m.n., goosse h., leduc g., martrat b., addison j.a., mortyn g., oppo d.w., seidenkrantz m.-s., sicre m.-a., phipps s.j., selvaraj k., thirumalai k., filipsson h.l. & ersek v. 2015. robust global ocean cooling trend for the pre-industrial common era. nature geoscience 8, 671–677, doi: 10.1038/ngeo2510. mckee b.a., nittrouer c.a. & demaster d.j. 1983. concepts of sediment deposition and accumulation applied to the continental shelf near the mouth of the yangtze river. geology 11, 631–633, doi: 10.1130/0091-7613(1983)11<631:cosdaa>2.0.co;2. mehrbach c., culberson c.h., hawley j.e. & pytkowicx r.m. 1973. measurement of the apparent dissociation constants of carbonic acid in seawater at atmospheric pressure. limnology and oceanography 8, 897–907, doi: 10.4319/lo.1973.18.6.0897. michel c., legendre l., demers s. & therriault j.c. 1988. photoadaptation of sea ice microalgae in springtime: photosynthesis and carboxylating enzymes. marine ecology progress series 50, 177–185, 10.3354/meps050177. moffa-sánchez p., born a., hall i.r., thornalley d.j.r. & barker s. 2014. solar forcing of north atlantic surface temperature and salinity over the past millennium. nature geoscience 7, 275–278, doi: 10.1038/ngeo2094. moffa-sánchez p. & hall i.r. 2017. north atlantic variability and its links to european climate over the last 3000 years. nature communication 8, article no. 1726, doi: 10.1038/s41467-017-01884-8. moffa-sánchez p., moreno-chamarro e., reynolds d.j., ortega p., cunningham l., swingedouw d., amrhein d.e., halfar j., jonkers l., jungclaus j.h, perner k., wanamaker a. & yeager s. 2019. variability in the northern north atlantic and arctic oceans across the last two millennia: a review. paleoceanography and paleoclimatology 34, 1399–1436, doi: 10.1029/2018pa003508. mucci a.1983. the solubility of calcite and aragonite in seawater at various salinities, temperatures and at one atmosphere pressure. american journal of science 283, 781–799, doi: 10.2475/ajs.283.7.780. müller j., werner k., stein r., fahl k., moros m. & jansen e. 2012. holocene cooling culminates in sea-ice oscillations in fram strait. quaternary science reviews 47, 1–14, doi: 10.1016/j.quascirev.2012.04.024. neukom r., steiger n., gómez-navarro j.j., wang j. & werner j.p. 2019. no evidence for globally coherent warm and cold periods over the preindustrial common era. nature 571, 550–554, doi: 10.1038/s41586-019-1401-2. nürnberg d. 1995. magnesium in tests of neogloboquadrina pachyderma sinistral from high northern and southern latitudes. journal of foraminiferal research 25, 350–368, doi: 10.2113/gsjfr.25.4.350. olsen a., omar a.m., jeansson e., anderson l.g. & bellerby r.g.j. 2010. nordic seas transit time distributions and anthropogenic co2. journal of geophysical research—oceans 115, c05005, doi: 10.1029/2009jc005488. owrid g., socal g., civitarese g., luchetta a., wiktor j., nӧthig e.m., andreassen i., schauer u. & strass v. 2000. spatial variability of phytoplankton, nutrients and new production estimates in the waters around svalbard. polar research 19, 155–171, doi: 10.1111/j.1751-8369.2000.tb00340.x. pados t. & spielhagen r.f. 2014. species distribution and depth habitat of recent planktic foraminifera in fram strait, arctic ocean. polar research 33, article no. 22483, doi: 10.3402/polar.v33.22483. pados t., spielhagen r.f., bauch d., meyer h. & segl m. 2015. oxygen and carbon isotope composition of modern planktic foraminifera and near-surface waters in the fram strait (arctic ocean)—a case study. biogeosciences 12, 1733–1752, doi: 10.5194/bg-12-1733-2015. parker f.l. 1962. planktonic foraminiferal species in pacific sediments. micropaleontology 8, 219–254. pathirana i., knies j., felix m., mann u. & ellingsen i. 2015. middle to late holocene paleoproductivity reconstructions for the western barents sea: a model-data comparison. arktos 1, article no. 20, doi: 10.1007/s41063-015-0002-z. pawłowska j., zajączkowski m., łącka m., lejzerowicz f., esling p. & pawłowski j. 2016. palaeoceanographic changes in hornsund fjord (spitsbergen, svalbard) over the last millennium: new insights from ancient dna. climate of the past 12, 1459–1472, doi: 10.5194/cp-12-1459-2016. peeters f.j.c., brummer g.a. & ganssen g. 2002. the effect of upwelling on the distribution and stable isotope composition of globigerina bulloides and globigerinoides ruber (planktic foraminifera) in modern surface waters of the nw arabian sea. global and planetary change 34, 269–291, doi: 10.1016/s0921-8181(02)00120-0. perner k., moros m., lloyd j.m., jansen e. & stein r. 2015. mid to late holocene strengthening of the east greenland current linked to warm subsurface atlantic water. quaternary science reviews 129, 296–307, doi: 10.1016/j.quascirev.2015.10.007. peterson l.c. & prell w.l. 1985. carbonate dissolution in recent sediments of the eastern equatorial indian ocean: preservation patterns and carbonate loss above the lysocline. marine geology 64, 259–290, doi: 10.1016/0025-3227(85)90108-2. petró s.m., pivel m.a.g. & coimbra j.c. 2018. foraminiferal solubility rankings: a contribution to the search for consensus. journal of foraminiferal research 48, 301–313, doi: 10.2113/gsjfr.48.4.301. pierrot d., lewis e. & wallace d.w.r. 2006. ms excel program developed for co2 system calculations, ornl/cdiac-105. oak ridge, tn: carbon dioxide information analysis center, oak ridge national laboratory, u.s. department of energy. reigstad m., wassmann p., riser c.w., øygarden s. & rey f. 2002. variations in hydrography, nutrients and chlorophyll a in the marginal ice-zone and the central barents sea. journal of marine systems 38, 9–29, doi: 10.1016/s0924-7963(02)00167-7. rasmussen t.l. & thomsen e. 2015. paleoceanographic development in storfjorden, svalbard, during the deglaciation and holocene: evidence from benthic foraminiferal records. boreas 44, 24–44, doi: 10.1111/bor.12098. rasmussen t.l., thomsen e., skirbekk k., ślubowska-woldengen m., klitgaard kristensen d. & koç n. 2014. spatial and temporal distribution of holocene temperature maxima in the northern nordic seas: interplay of atlantic, arctic and polar water masses. quaternary science reviews 92, 280–291, doi: 10.1016/j.quascirev.2013.10.034. rasmussen t.l., thomsen e., troelstra s.r., kuijpers a. & prins m. 2003. millennial scale glacial variability versus holocene stability: changes in planktic and benthic foraminifera faunas and ocean circulation in the north atlantic during the last 60,000 years. marine micropaleontology 47, 143–176, doi: 10.1016/s0377-8398(02)00115-9. rebotim a., voelker a.h.l., jonkers l., waniek j.j., meggers h., schiebel r., fraile i., schulz m. & kucera m. 2017. factors controlling the depth habitat of planktonic foraminifera in the subtropical eastern north atlantic. biogeosciences 14, article no. 827, doi: 10.5194/bg-14-827-2017. reimer p.j., bard e., bayliss a., beck j.w., blackwell p.p., ramsey c.b., buck c.e., cheng h., edwards r.l., friedrich m., grootes p.m., guilderson t.p., haflidason h., hajdas i., hatté c., heaton t.j., hoffmann d.l., hogg a.g., hughen k.a., kaiser k.f., kromer b., manning s.w., niu m., reimer r.w., richards d.a., scott e.m., southon j.r., staff r.a., turney c.s.m. & van der plicht j. 2013. intcal13 and marine13 radiocarbon age calibration curves, 0–50,000 years cal bp. radiocarbon 55, 1869–1887, doi: 10.2458/azu_js_rc.55.16947. rhines p., häkkinen s. & josey s.a. 2008. is oceanic heat transport significant in the climate system? in r.r. dickson et al. (eds.): arctic–subarctic ocean fluxes: defining the role of the northern seas in climate. pp. 87–109. dordrecht: springer. robbins j.a. & edgington d.n. 1975. determination of recent sedimentation rates in lake michigan using pb-210 and cs-137. geochimica et cosmochimica acta 39, 285–304, doi: 10.1016/0016-7037(75)90198-2. rudels b. 1996. the thermohaline circulation in the arctic ocean and in the greenland sea. philosophical transactions of the royal society london a352, 287–299, doi: 10.1098/rsta.1995.0071. rudels b., meyer r., fahrbach e., ivanov v.v., østerhus s., quadfasel d., schauer u., tverberg v. & woodgate r.a. 2000. water mass distribution in fram strait and over the yermak plateau in summer 1997. annals of geophysics 18, 687–705, doi: 10.1007/s00585-000-0687-5. rueda g., fietz s. & rosell-melé a. 2013. coupling of air and sea surface temperatures in the eastern fram strait during the last 2000 years. holocene 23, 692–698, doi: 10.1177/0959683612470177. russell a.d., hönisch b., spero h.j. & lea d.w. 2004. effects of seawater carbonate ion concentration and temperature on shell u, mg, and sr in cultured planktonic foraminifera. geochimica et cosmochimica acta 68, 4347–4361, doi: 10.1016/j.gca.2004.03.013. sakshaug e. 1997. biomass and productivity distributions and their variability in the barents sea. ices journal of marine science 54, 341–350, doi: 10.1006/jmsc.1996.0170. sakshaug e. & slagstad d. 1992. sea ice and wind: effects on primary productivity in the barents sea. atmosphere–ocean 30, 579-591, doi: 10.1080/07055900.1992.9649456. sarnthein m., van kreveld s., erlenkeuser h., grootes p.m., kucera m., pflaumann u. & schulz m. 2003. centennial-to-millennial-scale periodicities of holocene climate and sediment injections off the western barents shelf, 75 °n. boreas 32, 447–461, doi: 10.1111/j.1502-3885.2003.tb01227.x. sarnthein m. & werner k. 2017. early holocene planktic foraminifers record species-specific 14c reservoir ages in arctic gateway. marine micropaleontology 135, 45–55, doi: 10.1016/j.marmicro.2017.07.002. schiebel r., spielhagen r.f., garnier j., hagemann j., howa h., jentzen a., martínez-garcia a., meilland j., michel e., repschläger j., salter i., yamasaki m. & haug g. 2017. modern planktic foraminifers in the high-latitude ocean. marine micropaleontology 136, 1–13, doi: 10.1016/j.marmicro.2017.08.004. sicre m.-a., hall i.r., mignot j., khodri m., ezat u., truong m.-x., eiríksson j. & knudsen k.l. 2011. sea surface temperature variability in the subpolar atlantic over the last two millennia. paleoceanography 26, pa4218, doi: 10.1029/2011pa002169. sicre m.-a., jacob j., ezat u., rousse s., kissel c., yiou p., eiríksson j., knudsen k.-l., jansen e. & turon j.-l. 2008. decadal variability of sea surface temperatures off north iceland over the last 2000 years. earth and planetary science letters 268, 137–142, doi: 10.1016/j.epsl.2008.01.011. simstich j., sarnthein m. & erlenkeuser h. 2003. paired delta 18o signals of neogloboquadrina pachyderma (s) and turborotalita quinqueloba show thermal stratification structure in nordic seas. marine micropaleontology 48, 107–125, doi: 10.1016/s0377-8398(02)00165-2. shackleton n.j. 1974. attainment of isotopic equilibrium between ocean water and the benthonic foraminifera genus uvigerina: isotopic changes in the ocean during the last glacial. centre national de la recherche scientifique colleagues internationeau 219, 203–209. skogseth r., smedsrud l.h., nilsen f. & fer i. 2008. observations of hydrography and downflow of brine-enriched shelf water in the storfjorden polynya, svalbard. journal of geophysical research—oceans 113, c08049, doi: 10.1029/2007jc004452. smith w.o. jr., baumann m.e.m., wilson d.l. & aletsee l. 1987. phytoplankton biomass and productivity in the marginal ice zone of the fram strait during summer 1984. journal of geophysical research—oceans 92, 6777–6786, doi: 10.1029/jc092ic07p06777. smith w.o. & sakshaug e. 1990. polar phytoplankton. in w.o. smith jr. (ed.): polar oceanography. part b. chemistry, biology and geology. pp. 477–525. new york: academic press. spero h.j., bijma j., lea d.w. & bemis b.e. 1997. effect of seawater carbonate concentration on foraminiferal carbon and oxygen isotopes. nature 390, 497–500. spielhagen r.f., werner k., aagaard-sørensen s., zamelczyk k., kandiano e., budeus g., husum k., marchitto t. & hald m. 2011. enhanced modern heat transfer to the arctic by warm atlantic water. science 331, 450–453, doi: 10.1126/science.1197397. stuiver m. & reimer p.j. 1993. extended 14c data base and revised calib 3.0 14c age calibration program. radiocarbon 35, 215–230, doi: 10.1017/s0033822200013904. telford r.j. & birks h.j.b. 2005. the secret assumption of transfer functions: problems with spatial autocorrelation in evaluating model performance. quaternary science reviews 24, 2173–2179, doi: 10.1016/j.quascirev.2005.05.001. thunell r. & honjo s. 1981. calcite dissolution and the modification of planktonic foraminiferal assemblages. marine micropaleontology 6, 169–182, doi: 10.1016/0377-8398(81)90004-9. tremblay j.-e. & gagon j. 2009. the effects of irradiance and nutrient supply on the productivity of arctic waters: a perspective on climate change. in j.c.j. nihoul & a.g. kostianoy (eds.): influence of climate change on the changing arctic and sub-arctic conditions. pp. 73–93. dordrecht: springer. walczowski w., beszczyńska-möller a., wieczorek p., merchel m. & grynczel a. 2017. oceanographic observations in the nordic sea and fram strait in 2016 under the io pan long-term monitoring program arex. oceanologia 59, 187–194, doi: 10.1016/j.oceano.2016.12.003. walczowski w. & piechura j. 2011. influence of the west spitsbergen current on the local climate. international journal of climatology 31, 1088–1093, doi: 10.1002/joc.2338. wassmann p., ratkova t., andreassen i., vernet m., pedersen f. & rey f. 1999. spring bloom development in the marginal ice zone and the central barents sea. marine ecology 20, 321–346, doi: 10.1046/j.1439-0485.1999.2034081.x. weinkauf m., kunze j., waniek j. & kucera m. 2016. seasonal variation in shell calcification of planktonic foraminifera in the ne atlantic reveals species-specific response to temperature, productivity, and optimum growth conditions. plos one 11, e0148363, doi: 10.1371/journal.pone.0148363. werner k., müller j., husum k., spielhagen r.f., kandiano e.s. & polyak l. 2016. holocene sea subsurface and surface water masses in the fram strait—comparisons of temperature and sea-ice reconstructions. quaternary science reviews 147, 194–209, doi: 10.1016/j.quascirev.2015.09.007. werner k., spielhagen r.f., bauch d., hass h.c., kandiano e. & zamelczyk k. 2011. atlantic water advection to the eastern fram strait—multiproxy evidence for late holocene variability. palaeogeography, palaeoclimatology, palaeoecology 308, 264–276, doi: 10.1016/j.palaeo.2011.05.030. williams k.m. 1993. ice sheet and ocean interactions, margin of the east greenland ice sheet (14 ka to present): diatom evidence. paleoceanography 8, 69–83, doi: 10.1029/92pa02591. wollenburg j.e., knies j. & mackensen a. 2004. high-resolution paleoproductivity fluctuations during the past 24 kyr as indicated by benthic foraminifera in the marginal arctic ocean. palaeogeography, palaeoclimatology, palaeoecology 204, 209–238, doi: 10.1016/s0031-0182(03)00726-0. van aken h.m. 2006. the oceanic thermohaline circulation: an introduction. dordrecht: springer. vincent e. & berger w.h. 1981. planktonic foraminifera and their use in paleoceanography. in c. emiliani (ed.): the sea. pp. 1025–1119. new york: wiley interscience. vinje t.e. 1977. sea ice conditions in the european sector of the marginal seas of the arctic, 1966–75. norsk polarinstitutt årbok. 1975, 163–174. volkmann r. 2000. planktic foraminifer ecology and stable isotope geochemistry in the arctic ocean: implications from water column and sediment surface studies for quantitative reconstructions of oceanic parameters. berichte zur polarforschung 361. bremerhaven: alfred wegener institute of polar and marine research. volkmann r. & mensch m. 2001. stable isotope composition (δ18o, δ13c) of living planktic foraminifers in the outer laptev sea and the fram strait. marine micropaleontology 42, 163–188, doi: 10.1016/s0377-8398(01)00018-4. zamelczyk k., rasmussen t., husum k. & hald m. 2013. marine calcium carbonate preservation vs. climate change over the last two millennia in the fram strait: implications for planktic foraminiferal paleostudies. marine micropaleontology 98, 14–27, doi: 10.1016/j.marmicro.2012.10.001. doi:10.3402/polar.v34.23947 r e s e a r c h / r e v i e w a r t i c l e the effect of temperature on egg development rate and hatching success in calanus glacialis and c. finmarchicus agata weydmann,1,2 adrian zwolicki,3 krzysztof muś4 & sławomir kwaśniewski1 1 institute of oceanology, polish academy of sciences, powstancow warszawy st. 55, pl-81-712 sopot, poland 2 institute of oceanography, university of gdansk, piłsudskiego 46, pl-81-378, gdynia, poland 3 department of vertebrate ecology and zoology, university of gdansk, wita stwosza 59, pl-80-308, gdansk, poland 4 bird migration research station, university of gdansk, wita stwosza 59, pl-80-308, gdansk, poland keywords zooplankton; arctic; climate change; tipping point; bĕlehrádek’s temperature function; bayesian statistics. correspondence agata weydmann, institute of oceanography, university of gdansk, piłsudskiego 46, pl-81-378, gdynia, poland. e-mail: agataw@ug.edu.pl abstract the pelagic copepods calanus glacialis and c. finmarchicus are important components of arctic marine ecosystems. projected climate warming may influence the roles they play in the ecosystem. arctic c. glacialis and boreal c. finmarchicus eggs were incubated at temperatures of 0, 2.5, 5, 7.5 and 108c to investigate the effects of increasing temperature on egg development rate and hatching success. the effect of increasing temperature on median development time, described by bĕlehrádek’s temperature function, was examined using a bayesian approach. for the studied temperature range, we observed the increase of egg development rates with the increasing temperature, although there was no change in hatching success. calanus finmarchicus eggs hatched significantly faster than c. glacialis above approximately 28c; the difference was progressively larger at higher temperatures. this may indicate that the boreal species have physiological advantages in areas where ambient temperatures increase, which may lead to c. finmarchicus outcompeting the arctic species in situations where timing is important, for example, in relation to spring bloom dynamics. development time to hatching (dh) was evaluated using bĕlehrádek’s model and a set of different assumptions. the models that best fitted our data were those with species-specific parameters: dh (h) �5940 (t�9.7)�1.63 for c. finmarchicus and dh (h) �14168 (t�14)�1.75 for c. glacialis. calanus species are among the key components of arctic ecosystems on account of their high biomass and their role in food chains. they are predominant grazers and important prey items for other zooplankton species, fish and seabirds such as the little auk (alle alle) (karnovsky et al. 2003; falk-petersen et al. 2007). calanus finmarchicus (gunnerus 1770) is a boreal species that is widely distributed in the north atlantic and european arctic (jaschnov 1970; planque & batten 2000; weydmann et al. 2014). in the barents and norwegian seas, as well as in disko bay, it has a one-year life cycle, and spawns during or just after the spring phytoplankton bloom, which occurs in these areas between march and may (niehoff et al. 2002; madsen et al. 2008). its sibling species calanus glacialis (jaschnov 1955), which is an arctic species, spawns on shelves, along continental slopes and in fjords (jaschnov 1970; conover 1988; weydmann et al. 2013). it uses its internal lipid reserves to develop gonads before the bloom, but requires energy from either ice-algae or phytoplankton blooms to maximize egg production rates (hirche & kattner 1993; madsen et al. 2008; søreide et al. 2010). if the present trend of climate warming continues, current knowledge predicts this will have a substantial impact on the functioning of marine ecosystems in the arctic (wassmann 2011). temperature affects every aspect of zooplankton life, from cellular processes to behaviour, development and fitness (huntley & lopez 1992; clarke 2003), and warming beyond a species’ thermal tolerance could modify these aspects. for example, changes in polar research 2015. # 2015 a. weydmann et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2015, 34, 23947, http://dx.doi.org/10.3402/polar.v34.23947 (page number not for citation purpose) http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/23947 http://dx.doi.org/10.3402/polar.v34.23947 development time can lead to a tipping point in the structure and functioning of arctic marine ecosystems (carstensen & weydmann 2012). increasing temperatures may especially influence the arctic species c. glacialis, whose egg production rate was found to stabilize at 2.58c (kjellerup et al. 2012) and eventually decrease in temperatures above 58c (pasternak et al. 2013). at the same time, the presence and biomass of this species in the nordic seas was observed to decrease with ambient temperatures above the critical threshold of ca. 68c (carstensen et al. 2012). additionally, a positive balance between ingestion and respiration was found to cease above the same (58c) temperature threshold (alcaraz et al. 2013). none of the above effects was observed in parallel studies concerning the boreal c. finmarchicus at these temperatures (carstensen et al. 2012; pasternak et al. 2013). the early development of calanus species has been studied in different aspects, such as the influence of temperature (mclaren et al. 1969; corkett et al. 1986); both temperature and food availability (campbell et al. 2001; cook et al. 2007) and pyrene exposure and temperature (grenvald et al. 2013), although the authors did not focus on the problem of egg developmental time and hatching success under extreme temperatures. development rates are routinely described by bĕlehrádek’s (1935) temperature function: dh �a (t � a)b, where dh (development time to hatching) is the egg development time to hatching, t is the temperature and a, b and a are fitted parameters defining the properties of species response curves. the aim of this study was to investigate the effects of temperature on arctic c. glacialis and boreal c. finmarchicus egg development rate and hatching success, in order to examine the implications of a warming arctic scenario. another goal was to examine the correctness of bĕlehrádek’s temperature function parameters, known from earlier studies, when used for the experimentally obtained data set over a relatively large temperature range. materials and methods zooplankton collection and experiments zooplankton were collected from vertical tows with a multi plankton sampler (hydro-bios; kiel, germany) or a wp-2 type net (hydro-bios) using a large volume cod end bucket (both nets with 0.180 mm mesh size) during the cruise of the rv jan mayen (currently rv helmer hanssen) to the north-west barents and north-east greenland seas in june 2009 (four sampling stations). in april�may 2010 we used a wp-2 net (mesh size 0.180 mm) in hornsund, a fjord located at the southwestern tip of spitsbergen. in 2009, the mean water temperatures at the zooplankton sampling depths ranged from 1.288c (station atp 3; 778 08.6?n 288 11.0?e; 190 m) to 2.668c (station atp 6; 798 56.0?n 148 43.1?e; 123 m), whereas in 2010 in hornsund it was 0.38c. the mean chlorophyll a concentrations in the 0�100 m water layer in 2009, ranged from 0.89 (station atp 7; 768 29.7?n 288 02.0?e; 142 m) to 1.17 mg m�3 at station atp 6. in 2010 the samples were collected from 50 m to the surface at two stations, and chlorophyll a was not measured. the experiments in 2009 and 2010 were performed aboard the rv jan mayen and at the polish polar station in hornsund, respectively, as a series of incubations at temperatures of 08c, 2.58c, 58c, 7.58c and 108c. females of calanus glacialis and c. finmarchicus, sorted out from the zooplankton samples at the given stations, were transferred simultaneously to 250 ml beakers filled with the filtered seawater. the beakers were equipped with suspended inserts, which had mesh on the bottom, allowing the eggs to pass through, while keeping the females away from them and were reared in temperatures close to ambient (in 2009 t �2.58c, in 2010 t �08c) for egg shedding. in 2009 we collected eggs from 69 females of c. finmarchicus and 196 of c. glacialis, while in 2010 it was 19 and 32, respectively. usually five females were placed in one beaker; they were not fed and kept until eggs were produced. the healthy-looking eggs were collected from the rearing beakers with females every 12 h, transported gently with a pipette to separate petri dishes and incubated in laboratory coolers (type chl 1b) at the experimental temperatures. to reduce the effects of females or in situ environmental conditions on the results, the eggs collected from groups of females from the same station were mixed and split into separate dishes (25 eggs per dish for c. finmarchicus and 30 eggs per dish for c. glacialis), which were set at all experimental temperatures. in total, we used 54 petri dishes of 60 ml volume for c. finmarchicus (14 in 2009 and 40 in 2010) and 104 for c. glacialis (31 in 2009 and 73 in 2010); they were equally distributed among temperatures and treated as replicates in the following statistical analyses. the time ‘‘0’’ in our experiment is understood as the beginning of the egg incubation period, not as the exact time of egg release by females. the state of the reared eggs and the number of nauplii and unhatched eggs were checked daily, if possible, every 12 h. incubations were continued until all the eggs hatched or showed signs of decay, which usually took around a week (168 h). calanus egg development rate and hatching success a. weydmann et al. 2 (page number not for citation purpose) citation: polar research 2015, 34, 23947, http://dx.doi.org/10.3402/polar.v34.23947 http://www.polarresearch.net/index.php/polar/article/view/23947 http://dx.doi.org/10.3402/polar.v34.23947 statistical analysis to properly evaluate all sources of uncertainty when applying bĕlehrádek’s temperature function to the experimentally obtained data set, we decided to employ bayesian statistics (brooks 2003; clark 2005). as a programming tool, we chose winbugs software, which is commonly used in ecological studies (lunn et al. 2000; kery 2010; lunn et al. 2012). to assess hatching success in the experimental temperatures, a bayesian linear model with three main factors*year (y), species (s) and temperature (t)* and their interactions*year�species interaction (ys), temperature�species interaction (ts), temperature�year interaction (ty)*was performed. the dependent variable was defined as logit(p), p �(k�1)/(n�2), where p is the mean value of hatching success probability, k is the number of hatched nauplii, and n is the total egg number. in total 10 000 samples of the joint posterior distribution from the reversible jump markov chain monte carlo (rj mcmc) simulation in three independent chains was generated in winbugs software (lunn et al. 2006; lunn et al. 2008). in addition, a brooks�gelman�rubin (b�g� r) test of chain convergence was successfully performed (brooks & gelman 1998). differences in egg development times between species and experimental temperatures were calculated for median hatching time, which was defined as the time at which half of the eggs had hatched. all 141 time-to-hatching log-median data were divided into 10 species-temperature cells (two species, five experimental temperatures), and the jarque�bera test of normality (jarque & bera 1987) was performed for each cell. in six cells, the p-value of the test was below or near 0.05, and six clear outliers were removed. repeated jarque�bera tests for the remaining 135 data values resulted in p-values of approximately 0.1 and above. for each model configuration, a number of models nm �2np were tested in winbugs. np represents the number of free (estimated) parameters in a particular configuration. for each parameter p, two cases were tested: models with common values of this parameter for both species (symbol p) and models with different values for each species c. finmarchicus and c. glacialis (symbol pp). for example, there are 2 np �4 models for np �2 estimated parameters a and b, with symbols: aa�bb, a�bb, aa�b and a�b. to compare different models and select the most plausible model, the deviance information criterion, dic(m), was estimated using winbugs (spiegelhalter et al. 2002) for each model m of nm number of models, following the calculation of ‘‘penalized’’ likelihood l(m) �exp{ �0.5 �dic(m)}. posterior probability of model m equals: p mð þ¼ l mð þ= xnm m¼1 l mð þ evidence in favour of model m against all other nm�1 models was calculated as follows (jeffreys 1961): evid mð þ¼ 2 � log10 p mð þ 1 � p mð þ ! jeffreys’ qualitative scale for evidence (where evidence 50: bad model quality, �0 and b1: not substantial, ]1 and b2: substantial, ]2 and b3: strong, ]3 and b4: very strong, ]4: decisive evidence) was also adopted (see lunn et al. 2012, chapter 8). the decisive level of evidence of a certain model indicates that all remaining models can be rejected from further analysis. to compare the results between species with other published data bĕlehrádek’s (1935) temperature function dh �a (t � a)b was used, where dh is median time to hatching in hours, t is temperature in celsius degrees, and a, b and a are fitted parameters. the parameters in bĕlehrádek’s function define properties of species response curves to temperature: a describes differences in slope, b is associated with differences in monotonic curvelinearity within natural temperature ranges and a is a species’ ‘‘biological zero’’ temperature (mclaren et al. 1969). a nonlinear regression was performed using a log transformed expression: loge dhð þ¼ loge a þ b � loge t � að þ; parameter a was ‘‘recovered’’ by exponentiation. the fit of bĕlehrádek’s temperature function to the experimental data was performed in three configurations: (i) with forced b � �2.05 as suggested by mclaren et al. (1969), which resulted in four models: a-( �2.05)-a, aa-( �2.05)-a, a-( �2.05)-aa, and aa-( �2.05)-aa; (ii) with a common parameter b estimated from data in four models: a�b�a, aa�b�a, a�b�aa, and aa�b�aa; (iii) with all parameters free, to determine the function that best fitted our data in eight models: a�b�a, aa�b�a, a�b�aa, aa�b�aa, a�bb�a, aa�bb�a, a�bb�aa, and aa�bb�aa. in each configuration, the most probable model was selected for further evaluation by the dic described above. the ratio of hatching times between species as a function of temperature was also estimated for the model results that gave the best model fit. due to a very strong correlation among the estimated bĕlehrádek’s model parameters, which resulted in substantial autocorrelations in most of the mcmc chains, in each of the total 12 simulations, the following calculation regime was applied: 20 000 initial iterations followed by one million main iterations recorded every 100 iterations a. weydmann et al. calanus egg development rate and hatching success citation: polar research 2015, 34, 23947, http://dx.doi.org/10.3402/polar.v34.23947 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23947 http://dx.doi.org/10.3402/polar.v34.23947 (the ‘‘thin’’ value was 100), in three independent chains. the b�g�r test of convergence was always performed. results the total number of 1261 eggs of calanus finmarchicus (501 in 2009 and 760 in 2010) and 3323 eggs of c. glacialis (1477 in 2009 and 1846 in 2010) were selected from the mixed egg pool and used for the following incubation experiments (table 1). hatching occurred at all experimental temperatures with a considerably high success (fig. 1). the proportion of hatched nauplii for c. finmarchicus ranged from 74.5% at 58c in 2010 to 95.4% in the highest temperature in 2009, whereas in c. glacialis it ranged from 71.3% at 108c in 2009 to 92.6% at 2.58c in 2010 (table 1). according to the bayesian comparison of the linear models with three main factors and the interactions between them, which was performed using rj mcmc, the most probable, at almost a decisive level of evidence (evidence �3.9, table 2), was the null model with no parameters. according to this analysis, the hatching success was the same at all temperatures, and for both years and species (see fig. 1). in the first configuration of the tested bĕlehrádek’s models, with forced b� �2.05, dh (s)�a(s) [t � a(s)]�2.05, a reasonable fit was achieved only by the model type aa-( �2.05)-aa (table 3). according to this model, the experimental results were fitted to the following hatching time functions: dh (h) �28420 (t�13)�2.05 for c. finmarchicus and dh (h) �45838 (t�16.9)�2.05 for c. glacialis. similarly, in the second configuration dh (s) �a(s) [t � a(s)]b with the value of a common parameter b estimated as b � �1.73 based on the data from our experiments, only the model type aa�b�aa was qualified as decisive (table 3). in this case, the developmental functions were dh (h) �8629 (t�10.5) �1.73 for c. finmarchicus and dh (h) �12977 (t�13.7)�1.73 for c. glacialis. model aa�b�aa was much more probable than model aa-(�2.05)-aa, with the decisive evidence criterion value above 4.5 (difference in dic is 10.5 in favour of the model with common parameter b; see table 3). the comparison of bĕlehrádek’s models with different fitted parameters a, b and a resulted in the highest satisfactory evidence (table 3) only for the model with all free parameters aa�bb�aa: dh (s) �a(s) [t � a(s)]b(s). according to this model, the experimental results were best fitted to the following hatching time functions: dh (h) �5940 (t�9.7)�1.63 for c. finmarchicus and dh (h) �14168 (t�14)�1.75 for c. glacialis (fig. 2). the ratio of hatching time between species based on the model aa �bb�aa (fig. 3) showed the higher rates for the arctic species in the lowest experimental temperatures, i.e., from 0 to ca. 18c. with the increasing temperature, c. finmarchicus eggs hatched faster; taking the995% bayesian credibility interval into account, the difference between species was evident above 2.68c. these results are supported by the evidence of differences in hatching times between species calculated for temperature intervals (table 4), which confirmed that for temperatures between 0 and 0.78c c. glacialis egg hatching time was shorter, whereas c. finmarchicus eggs hatched substantially faster in temperatures above 2.08c; however, the evidence was decisive only above 3.68c. discussion the egg development times for both of the sibling copepod species calanus finmarchicus and c. glacialis, which cooccur in the arctic, was shorter with increasing temperature but did not lead to decreased hatching success, even at the maximum experimental temperature. hatching was faster in higher temperatures, similar to the results of earlier studies. the hatching rates in c. glacialis obtained by mclaren et al. (1969) were mostly within the 995% table 1 number of eggs and hatching success of calanus finmarchicus and c. glacialis in the experimental temperatures. species temperature (8c) no. of eggs 2009 hatching success (%) 2009 no. of eggs 2010 hatching success (%) 2010 c. finmarchicus 0 81 84.7 101 93.1 2.5 124 93.4 138 90.6 5 85 95.2 145 74.5 7.5 126 89.4 171 76.0 10 85 95.4 205 87.8 total n 501 91.4 760 83.8 c. glacialis 0 234 74.8 301 86.0 2.5 322 79.5 378 92.6 5 318 77.9 425 85.6 7.5 281 82.8 380 81.3 10 322 71.3 362 89.5 total n 1477 77.6 1846 87.0 calanus egg development rate and hatching success a. weydmann et al. 4 (page number not for citation purpose) citation: polar research 2015, 34, 23947, http://dx.doi.org/10.3402/polar.v34.23947 http://www.polarresearch.net/index.php/polar/article/view/23947 http://dx.doi.org/10.3402/polar.v34.23947 bayesian credibility interval of this study (fig. 2); hence, they do not differ substantially. however, grenvald et al. (2013), in the control of their pyrene exposure experiments, measured earlier median hatching times for both species. in the case of c. finmarchicus (marschall & orr 1953 cited in mclaren et al. 1969), our observations of median hatching time resulted in slightly higher but comparable values, and this discrepancy might be due to small differences in experimental temperatures because the time ‘‘0’’ in our experiment was understood as the beginning of the egg incubation period, not as the exact time of egg shedding by females. other factors that might have influenced our results were: the temperature in which females were maintained to shed eggs (2.58c in 2009), which could accelerate egg development especially at lower temperatures, and the lower number of c. finmarchicus females and, consequently, eggs, than of c. glacialis. interestingly, we did not notice substantial differences in egg development rates and hatching success between calanus females collected from different ambient conditions (open sea in 2009, fjord in 2010). in addition, the ranges in hatching times and success did not differ substantially between replicates (see the whiskers in fig. 2). therefore, we believe that the locations of the sampling stations, sea temperature, and in situ chlorophyll concentrations did not have any substantial effect on the studied processes. however, since the number of eggs produced at each station varied, similarly as measured chlorophyll a concentrations, the results of egg-hatching experiments could have been biased towards stations where egg production rates were higher due to higher food availability (hirche & kattner 1993). kjellerup et al. (2012), who examined the effects of temperature and food for c. finmarchicus and c. glacialis during three phases of the phytoplankton spring bloom in disko bay (western greenland), found that c. glacialis sampled before the bloom, and incubated with excess food, exhibited high specific egg production at temperatures between 0 and 2.58c, whereas egg production for c. finmarchicus more than tripled between 2.5 and 58c. the authors suggested that a future warmer ocean would reduce the advantage of early spawning by c. glacialis and that c. finmarchicus would become increasingly prevalent. in our experiments, the egg development time of arctic c. glacialis eggs was substantially longer than that of boreal c. finmarchicus above 2.08c and on the decisive level of evidence above 3.68c. grenvald et al. (2013) also fig. 1 relationship between the mean hatching success (%) and time (hours) in c. finmarchicus and c. glacialis in 2009 and 2010. table 2 bayesian linear model of hatching success, with three main factors and interactions performed by reversible jump markov chain monte carlo. all remaining models had a zero posterior probability. model probability evidence model quality null model 0.9889 3.9 very strong year*species 0.0031 �5.0 bad year 0.0030 �5.0 bad species 0.0018 �5.5 bad temperature*species 0.0015 �5.6 bad temperature 0.0011 �5.9 bad temperature*year 0.0005 �6.5 bad a. weydmann et al. calanus egg development rate and hatching success citation: polar research 2015, 34, 23947, http://dx.doi.org/10.3402/polar.v34.23947 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23947 http://dx.doi.org/10.3402/polar.v34.23947 demonstrated faster median hatching times in c. glacialis at lower temperatures (08c) and in c. finmarchicus at higher temperatures (108c); the authors explained this result by the different origin and specific temperature tolerance of each species. the observed retarding of c. glacialis egg development rate at higher temperatures in comparison to c. finmarchicus, may have crucial and accumulating effects on the subsequent developmental stages. the reproduction and growth of c. glacialis is connected with the timing of ice algal and phytoplankton blooms, therefore the change in the current primary production regime due to global warming, coupled with higher sea temperatures, may lead to a mismatch between the timing of blooms and the reproductive cycle of this key arctic grazer, while c. finmarchicus, which develops faster in higher temperatures, may take advantage of this situation. in comparison to other developmental stages, eggs are particularly vulnerable to predation because they do not have the ability to escape, and reduced hatching times could lead to reduced predation rates and higher population abundances. lower egg production rates with increasing temperatures (kjellerup et al. 2012; pasternak et al. 2013), coupled with longer egg development could eventually lead to decreasing numbers of the arctic species and shift zooplankton community structure towards a smaller zooplankton size spectrum that is predominated by c. finmarchicus, with lower energy content per individual (falk-petersen et al. 2007). such changes in the zooplankton community may have consequences for both terrestrial and marine lipid-driven arctic ecosystems (falk-petersen et al. 2007; stempniewicz et al. 2007; zwolicki et al. 2013). calanus glacialis was reported to exhibit a tipping point at an ambient temperature of 5�68c in its oceanic distribution (carstensen et al. 2012), as well as in the rate of metabolic processes (alcaraz et al. 2013). pasternak et al. (2013) measured the egg production of both species, at the same experimental temperatures as used in this study and found that the egg production rates of table 3 the comparison of bĕlehrádek’s models: with a common parameter b (forced b � �2.05 and estimated b � �1.73), with evidence �0 according to jeffreys’ qualitative scale for evidence; and with different configurations of fitted parameters a, b and a. the best model is in boldface. model deviance information criterion weight probability odds evidence model quality aa-( �2.05)-aa �215.8 266 0.9941 167 4.4 decisive aa-( �1.73)-aa �226.3 774 0.9970 337 5.1 decisive aa�bb�aa �231.5 538 0.8494 5.64 1.5 substantial aa�bb�a �224.1 13.2 0.0209 0.0214 �3.3 bad aa�b�aa �226.3 40.5 0.0640 0.0683 �2.3 bad aa�b�a �214.6 0.117 0.0002 0.000185 �7.5 bad a�bb�aa �226.3 41.1 0.0648 0.0693 �2.3 bad a �bb�a �217.3 0.454 0.0007 0.000717 �6.3 bad a�b�aa �206.6 0.0021 0.0000 3.31e�006 �11.0 bad a�b�a �204.5 0.000755 0.0000 1.19e�006 �11.8 bad fig. 2 relationship between median hatching time and temperature based on the best model aa�bb�aa, with 995% bayesian credibility interval shown by dotted lines, and the comparison of the obtained hatching rates with other studies. whiskers indicate ranges between replicates. fig. 3 ratio of hatching time (ht) for c. glacialis (cg) to ht for c. finmarchicus (cf) based on the best model aa�bb�aa, with 995% bayesian credibility interval. calanus egg development rate and hatching success a. weydmann et al. 6 (page number not for citation purpose) citation: polar research 2015, 34, 23947, http://dx.doi.org/10.3402/polar.v34.23947 http://www.polarresearch.net/index.php/polar/article/view/23947 http://dx.doi.org/10.3402/polar.v34.23947 c. finmarchicus increased with temperature over the entire tested range, but for c. glacialis the rates increased only in the range of 0�58c and decreased with further temperature increases. our experiments support the above findings, indicating that the temperature range of 5�68c can be suggested as a threshold value for the arctic c. glacialis in yet another biological characteristic that depends on temperature, the egg development time. the above-mentioned studies and our results identifying the potential temperature tipping point are based mainly on calanus individuals collected in the svalbard area, whereas some of the identified differences between calanus populations, e.g., by single nucleotide polymorphism in c. finmarchicus from the north atlantic (unal & bucklin 2010), may have an effect on the results obtained for individuals of populations from different locations. it is not unlikely that these population differences could be the reason for lower median hatching times obtained for c. glacialis and c. finmarchicus from western greenland (grenvald et al. 2013). from the tested models of bĕlehrádek’s temperature function, with different combination of parameters, the model with three different parameters for each species proved to be the most accurate. interestingly, parameter a, which is regarded as the species’ ‘‘biological zero’’ temperature (mclaren et al. 1969), was 3�48c lower for the arctic sibling in all versions of the model that we used. the commonly used model with a forced parameter b � �2.05 (e.g., corkett et al. 1986; campbell et al. 2001), which was postulated by mclaren et al. (1969) to be applied to all copepod species, gave the worst fit to our experimental data, especially for c. finmarchicus. we propose new, species-specific values for parameter b in bĕlehrádek’s temperature function for c. finmarchicus and c. glacialis egg hatching time, and we highlight the need to verify the parameters of important biological functions models. this issue is especially important due to the possibility of differences in temperature adaptations among populations of a single species over their distribution ranges, especially between regions where ambient temperatures are notably different. it is also worth noting that the use of bayesian methods allowed us to not only to compare different models describing limited experimental data but also select the best-supported model based on its statistical confidence. the methods also allowed us to yield a more accurate estimation of the critical value of an important biological variable. acknowledgements this research was funded by the arctic tipping points project, contract no. 226248 of the framework program 7 of the european union, the polish state committee for scientific research grant no. n n304 119834 and the ministry of science and higher education grant no. 1313/7. pr ue/2010/7. references alcaraz m., felipe j., grote u., arashkevich e. & nikishina a. 2013. life in a warming ocean: thermal thresholds and metabolic balance of arctic zooplankton. journal of plankton research 36, 3�10. bĕlehrádek j. 1935. temperature and living matter. vol. 8. (protoplasma-monographien.) berlin: borntraeger. brooks s.p. 2003. bayesian computation: a statistical revolution. philosophical transactions of the royal society a 361, 2681�2697. brooks s.p. & gelman a. 1998. alternative methods for monitoring convergence of iterative simulations. journal of computational and graphical statistics 7, 434�455. campbell r.g., wagner m.m., teegarden g.j., boudreau c.a. & durbin e.g. 2001. growth and development rates of the copepod calanus finmarchicus reared in the laboratory. marine ecology progress series 221, 161�183. carstensen j. & weydmann a. 2012. tipping points in the arctic: eyeballing or statistical significance? ambio 41, 34�43. carstensen j., weydmann a., olszewska a. & kwasniewski s. 2012. effects of environmental conditions on the biomass of calanus spp. in the nordic seas. journal of plankton research 34, 951�966. clark j.s. 2005. why environmental scientists are becoming bayesians. ecology letters 8, 2�14. table 4 evidence of differences in hatching times between species*calanus finmarchicus (cf) and c. glacialis (cg)*at the increasing temperatures based on the best model aa�bb�aa. temperature (8c) probability evidence model quality in favour 0.0�0.7 0.090�0.241 �2.0 to �1.0 substantial ht(cg) b ht(cf) 0.7�1.1 0.241�0.360 �1.0 to �0.5 not substantial ht(cg) b ht(cf) 1.1�1.7 0.360�0.640 �0.5�0.5 no evidence 1.7�2.0 0.640�0.759 0.5�1.0 not substantial ht(cg) � ht(cf) 2.0�2.6 0.759�0.909 1.0�2.0 substantial ht(cg) � ht(cf) 2.6�3.2 0.909�0.969 2.0�3.0 strong ht(cg) � ht(cf) 3.2�3.6 0.969�0.990 3.0�4.0 very strong ht(cg) � ht(cf) �3.6 �0.990 �4.0 decisive ht(cg) � ht(cf) a. weydmann et al. calanus egg development rate and hatching success citation: polar research 2015, 34, 23947, http://dx.doi.org/10.3402/polar.v34.23947 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/23947 http://dx.doi.org/10.3402/polar.v34.23947 clarke a. 2003. costs and consequences of evolutionary temperature adaptation. trends in ecology and evolution 18, 573�581. conover r.j. 1988. comparative life histories in the genera calanus and neocalanus in high latitudes of the northern hemisphere. hydrobiologia 167/168, 127�142. cook k.b., bunker a., hay s., hirst a.g. & speirs d.c. 2007. naupliar development times and survival of the copepods calanus helgolandicus and calanus finmarchicus in relation to food and temperature. journal of plankton research 29, 757�767. corkett c.j., mclaren a. & sevigny j.m. 1986. the rearing of the marine calanoid copepods calanus finmarchicus (gunnerus), c. glacialis jaschnov and c. hyperboreus kroyer with comment on the equiproportional rule. syllogeus 58, 539�546. falk-petersen s., timofeev s., pavlov v. & sargent j.r. 2007. climate variability and possible effects on arctic food chains: the role of calanus. in j.b. ørbæk et al. (eds.): arctic�alpine ecosystems and people in a changing environment. pp. 147�166. berlin: springer. grenvald j.c., nielsen t.g. & hjorth m. 2013. effects of pyrene exposure and temperature on early development of two co-existing arctic copepods. ecotoxicology 22, 184�198. hirche h.j. & kattner g. 1993. egg production and lipid content of calanus glacialis in spring: indication of a food-dependent and food-independent reproductive mode. marine biology 117, 615�622. huntley m.e. & lopez m.d.g. 1992. temperature-dependent production of marine copepods: a global synthesis. american naturalist 140, 201�242. jarque c.m. & bera a.k. 1987. a test for normality of observations and regression residuals. international statistical review 55, 163�172. jaschnov w.a. 1970. distribution of calanus species in the seas of the northern hemisphere. internationale revue gesamten hydrobiologie 55, 197�212. jeffreys h. 1961. theory of probability. 3rd edn. london: oxford university press. karnovsky n.j., weslawski j.m., kwasniewski s., walkusz w. & beszczynska-moeller a. 2003. foraging behavior of little auks in heterogeneous environment. marine ecology progress series 253, 289�303. kery m. 2010. introduction to winbugs for ecologists: a bayesian approach to regression, anova, mixed models and related analyses. amsterdam: academic press. kjellerup s., dunweber m., swalethorp r., nielsen t.g., moller e.f., markager s. & hansen b.w. 2012. effects of a future warmer ocean on the so-existing copepods calanus finmarchicus and c. glacialis in disko bay, western greenland. marine ecology progress series 447, 87�108. lunn d.j., best n. & whittaker j.c. 2008. generic reversible jump mcmc using graphical models. statistics and computing 19, 395�408. lunn d.j., jackson ch., best n., thomas a. & spiegelhalter d. 2012. the bugs book: a practical introduction to bayesian analysis. boca raton, fl: crc press. lunn d.j., thomas a., best n. & spiegelhalter d. 2000. winbugs*a bayesian modelling framework: concepts, structure, and extensibility. statistics and computing 10, 325�337. lunn d.j., whittaker j.c. & best n. 2006. a bayesian toolkit for genetic association studies. genetic epidemiology 30, 231�247. madsen s.j., nielsen t.g., tervo o.m. & söderkvist j. 2008. on the importance of feeding for egg reproduction of calanus finmarchicus and c. glacialis during the arctic spring. marine ecology progress series 353, 177�190. mclaren i., corkett c.j. & zillioux e.j. 1969. temperature adaptations of copepod eggs from the arctic to the tropics. biological bulletin 137, 486�493. niehoff b., madsen s.d., hansen b.w. & nielsen t.g. 2002. reproductive cycles of three dominant calanus species in disko bay, west greenland. marine biology 140, 567�576. pasternak a.f., arashkevich e.g., grote u., nikishina a.b. & solovyev k.a. 2013. different effects of increased water temperature on egg production of calanus finmarchicus and c. glacialis. oceanology 53, 547�553. planque b. & batten s.d. 2000. calanus finmarchicus in the north atlantic: the year of calanus in the context of interdecadal change. ices journal of marine science 57, 1528�1535. søreide j.e., leu e., berge j., graeve m. & falk-petersen s. 2010. timing of blooms, algal food quality and calanus glacialis reproduction and growth in a changing arctic. global change biology 16, 3154�3163. spiegelhalter d.j., best n.g., carlin b.p. & van der linde a. 2002. bayesian measures of model complexity and fit (with discussion). journal of the royal statistical society b 64, 583�639. stempniewicz l., blachowiak-samolyk k. & weslawski j.m. 2007. impact of climate change on zooplankton communities, seabird populations and arctic ecosystem*a scenario. deep-sea research part ii 54, 2934�2945. unal e. & bucklin a. 2010. basin-scale population genetic structure of the planktonic copepod calanus finmarchicus in the north atlantic ocean. progress in oceanography 87, 175�185. wassmann p. 2011. arctic marine ecosystems in an era of rapid climate change. progress in oceanography 90, 1�17. weydmann a., carstensen j., goszczko i., dmoch k., olszewska a. & kwasniewski s. 2014. shift towards the dominance of boreal species in the arctic: inter-annual and spatial zooplankton variability in the west spitsbergen current. marine ecology progress series 501, 41�52. weydmann a., søreide j.e., kwasniewski s., leu e., falkpetersen s. & berge j. 2013. ice-related seasonality in zooplankton community composition in a high arctic fjord. journal of plankton research 35, 831�842. zwolicki a., zmudczyńska-skarbek k.m., iliszko l. & stempniewicz l. 2013. guano deposition and nutrient enrichment in the vicinity of planktivorous and piscivorous seabird colonies in spitsbergen. polar biology 36, 363�372. calanus egg development rate and hatching success a. weydmann et al. 8 (page number not for citation purpose) citation: polar research 2015, 34, 23947, http://dx.doi.org/10.3402/polar.v34.23947 http://www.polarresearch.net/index.php/polar/article/view/23947 http://dx.doi.org/10.3402/polar.v34.23947 the downtonian and devonian vertebrates of spitsbergen. xv*. new heterostracans from the lower devonian red bay group, northern spitsbergen robert r. ilyes, yoshihide ohta and jonny guddingsmo ilyes, r. r . , ohta. y. & guddingsrno, j . 1995: the downtonian and devonian vertebrates of spitsbergen. xv* new heterostracans from the lower devonian red bay group, northern spitsbergen. polar research id(]), 33-42. a new vertebrate fauna consisting of two new species of heterostracans (jawless vertebrates), aiig1aspi.r glelsoiki (cyathaspididae) and proiopreraspis rnicra (pteraspididae), is described from the wulffberget member of the red bay conglomerate formation, northern spitsbergen. this is the oldest known vertebrate fauna of typical early devonian age on spitsbergen. the discovery of this vertebrate fauna improves the distribution and diversity of early vertebrates in the red bay group. robert r. ilyes arid yoshihide ohta. norsk polminstituit, p . 0. box. 5072, majorstua, n-0301 oslo. norway; jonny guddingsmo. geology diuision. instituff for biology and geology, university of trornsm. n-9037 tromsq?, norway. introduction is located at the base of the fraenkelryggen for the lower devonian red bay group is the lowermost vertebrate-bearing unit of the devonian “old red sandstone” deposits of spits bergen. the red bay group overlies the older siktefjellet group with an angular unconformity and is divided into four formations: the red bay conglomerate formation, the andreebreen for mation, the fraenkelryggen formation, and the ben nevis formation (fig. 1). the red bay conglomerate formation is further separated into three members, (from bottom to top) the wulffberget member, the rabotdalen member, and the princesse alicefjellet member. thirty vertebrate-bearing horizons have pre viously been recognised in the red bay group (blieck & heintz 1979), with the oldest being the “ p s a m m o ~ t e ~ s ” horizon. in the original inter pretation by kiaer & heintz (1939, this horizon mation. however, based on a re-examination of the data, gjelsvik & ilyes (1991) suggested that the “psammosteus” horizon is actually located in the yellow-green sandstones of the upper part of the andreebreen formation. gjelsvik & ilyes did not investigate the actual locality but re-inter preted the original field observations in relation to gee’s 1966 map. the oldest vertebrates from the “old red” deposits of spitsbergen prior to this study were reported by gjelsvik & ilyes (1991). who regarded most of their vertebrate localities to belong to the andreebreen formation. some scattered fragments of primitive spore plants and ostracods have been found in the rabotdalen member (murasov & mokin 1979), but no verte brates have been reported from below the andrcebreen formation until now. the new occurrence of heterostracans. both cvathasuidids and pteraspidids, in the wulffberget member of the red bay conglomerate is therefore signifi cant. the description of two new heterostracans * correctmi there has been an error in the numbering of the previous paper in the series “the downlonian and devonian vertebrates of spitsbergen”. blieck a b n. heintz’s “the cyathaspids of the red bay group (lower devonian) of spits bereen” (polar reg. 1 n . s . . 1983. dd. 49-73) should have been increases their diversity and stratigraphical dis tribution in the red bay group’ found one o f t h e authors (y. 0.) . , ~ .. xiv of the series and not xiii. n. heintz’s “the theolodont vertebrates in a limestone conelomerate assigned y ” sigurdia lafa n.g., n.sp. from the lower devonian at sigurdfjel let, spitsbergen” (norsk polarinsi. arbok 1970, pp. 112-116) was number xiii. the current paper is therefore number xv in the series ( a complete list of the previous publications in the to red bay conglomerate formation in the west however, been carried o u t on the ern end of richardvatnet, spitsbergen. no further studies series is found on pages 41-42). material. 34 r. r . ilyes et a l . 3 8 c formation member lithology ben nevis 900 m erer, . micaccous sandstone frznkelryggen mx) m grcy-green. yellowgrey %and/siltstone. basal grit andreebreen >100 m ~~ alternating red and green sand/siltstone red ba) conglomerate cnconformit! siktefjellet sandstone 350 m lilljeborgfjellet conelomerate 4 k j m princesse alirefjellet 300 m rabotdalen 20(1 m sandstone wulfibergct coarse. massive marble conglomerate 200 m matrix supported. quartz chip conglomerate grey-green. in lower part multicoloured -- grey-green sand/siltstone massive. polyniict conglomerate f i g . 1. stratigraphy and lithology of the red bay group and the siktefjellet group in northern spitsbergen (from gjelsvik & ilyes 1991 1 i i i . i material and methods the fossil material described here comes from one locality on hesteskoholmen, a small island located in the northwestern part of liefdefjorden (figs. 2 and 3 ) . the material has been collected in situ in the stratigraphic section. the cyathaspidids represent the majority of the vertebrates found at this locality. the specimens are preserved in a tough micaceous sandstone that can be prepared mech anically. the measurements employed follow those used by blieck & heintz (1983) for cya thaspidids (table 1). and blieck (1984) for ptera spidids (table 2). the specimens are deposited in the collections of the paleontologisk museum, oslo, and bear their catalog numbers (prefixed pmo). fig 2. map showing the new early devonian vertebrate locality on hesteskoholmen. northern spitsbergen. boxed area depicts arrashown on fig 3 . symbol,: 1. glacier andmoraine. 2. wood bay fm.. 3 . ben n e w fm. (rcd bay gi.): 4, frznkelryggen fm. (red bay g r . ) ; 5 . andreebreen fm. (red bay gr.): 6. wulffhergct mbr. (rcd bay gr ): 7 . siktefjellet sandstone: 8. lill]ehorgfjellet conglomerate: 9. phyllite and marble. 10. boundaries. 11. steep faults; 12. fault with dip: 13. thrusts: 14. covered b\ scree. geological setting the new vertebrate-bearing unit is located in t h e wulffberget member of the red bay con glomerate. it is a red sandstone bed interbedded in a less stratified, coarse, and massive marble dominated conglomerate (fig. 4). the con glomerate is of typical wulffberget member type, which forms the whole of the western part of the the downtonian and devonian vertebrates of spitsbergen 3.5 ~ fig. 3. local geology of hesteskoholmen and surrounding areas. arrow points to the new vertebrate locality island hesteskoholmen. the vertebrate-bearing bed is one of two sandstone beds interbedded in the conglomerate in this area, and the only one known to have vertebrates. the vertebrate-bearing sandstone is approxi mately 1.5 m thick and at least 8 m in length. to fig. 4. the geology of the new vertebrate locality in the wulffberget member of the red bay conglomerate formation. captions: sst, sandstone; cgl, conglomerate. the east the vertebrate-bearing unit is bounded by a local fault, and to the west an approximately 2 m thick conglomerate very rich in marble blocks occurs without a structural break. based on the field observations it is suggested that the vertebrate-bearing sandstone bed is a sandstone lens interbedded in the conglomerates of the wulffberget member. systematic paleontology order heterostraci lankester, 1868 family cyathaspididae kim, 1932 (cyathaspi dae) genus anglaspis jaekel, 1927 definition. see denison, 1964: 428. type species. cyathaspis macculloughi wood ward, 1891. other species. a . macculloughi (woodward, 1891) type species, a . insignis wills (1936), a . heintzi blieck & heintz (1983), a . elongata blieck & heintz (1983), a . expatriata denison (1964). anglaspis gjelsviki n. s p . figs. 5 , 6 and 7. 36 r . r . llyes ei al. etymology. named after t o r e gjelsvik for his work on the lower devonian stratigraphy of spitsbergen. h o l o y p e . dorsal shield p m o 141.565. paravpes. dorsal shields p m o 141.566 141.575; ventral shields p m o 141.576, p m o 141.577; branchial plate p m o 141.578; scales p m o 141.579-141.582. all from the same locality in the wulffherget member of the red bay con glomerate formation. locus typicirs and sfraruni rypicuni. hes teskoholmen; wulffberget member of the r e d bay conglomerate formation. diagnosis. a species of anglaspis with finer ornamentation ( 5 4 dentine ridges per mm) than all o t h e r species of this genus. and distinctive morphology of the dorsal shield. mrasirrenzerzts. table 1. description. t h e dorsal shield is narrow and gently d o m e d , with a prominent pineal macula. t h e lateral epitega form brims; shield constricted at the branchial openings. branchial plate long with a sharp lateral angulation. ornamentation of fine dentine ridges. 5-6/mm; sharply crested anteriorly and laterally. round crested on remain der of shield. lateral-line sensory canal system fig. 5 . anglmprsgjelrurki n . sp. dorsal view of holotype (dorsal shield). p m o 111 5 6 5 . 4 . 5 x . fig. 6. a r ~ g l ~ p i r g j e l s v i k i n . sp. pmo 141.574 sem micrograph showing detail of ornamentation on mid part of dorsal shield, 15 x . the downtonian and devonian vertebrates of spitsbergen 37 tuble 1. measurements (in mm) for anglaspis gjelsuiki n . sp. all measurements taken on dorsal shield except for length and width of ventral shield orbital width: 7-10 ( n = 9) orbital length: >5 (n = 9) total width: 10-13 ( n = 9) total length: 18-22 ( n = 9) pineal length: 4-5 (n = 9) postbranchial length: 3-6 (n = 9) width ventral shield: 10-12 (n = 3) length ventral shield: 18-20 (n = 3) dentine ridges/mm: 5-6 ( n = 9 +) unknown (the preservation of the shields makes it impossible to trace the lateral-line canal system). ventral shield is gently arched, almost flat, anteriorly and strongly arched posteriorly. discussion. this species is very similar to ang laspis insignis in size. the two forms differ, how ever, in the overall morphology of the dorsal shield. anglaspis gjelsuiki is narrower and the postbranchial length of the dorsal shield is greater than in a . insignis. this makes the posterior part of the dorsal shield more pointed in a . gjelsviki n sp. than in a . insignis. there is also a noticeable difference in the coarseness of the dentine ridges on the central part of the dorsal shield between the two forms, which is a very important taxo fig. 7. ang/arpis gjelsoiki n. sp. drawing of dorsal view of dorsal shield pmo 141.565, holotype. scale bar = 5 m m ; abbreviations: orb, orbit; bro, branchial opening. nomic difference. anglaspis insignis have the coarser ornamentation of the two, with 3-4 ridges per mm compared t o 5 4 per mm in this species. denison (1964) noted, however, that the coarse ness of the dentine ridges varies between 3.5 and 5 ridges per mm centrally in a. insignis. a study of the type material and other material of a . insignis in the collections of the paleontologisk museum, oslo, concludes that the coarseness varies only between 3 and 4 ridges per mm, just as stated by blieck & heintz (1983). the new form shows a very small individual variation in the coarseness of the dentine ridges, as do the other species of the genus anglaspis. the study of the type material suggests that the new form is a valid species, which can be sep arated from a . insignis by its noticeably finer ornamentation and distinctive morphology of the dorsal shield. family pteraspididae claypole, 1885 subfamily pteraspidinae claypole, 1885 genus protopteraspis leriche, 1924 dejinition. see elliot & dineley, 1983; 478. t y p e species. protopteraspis gosseleti leriche, 1924. other species. p . aquilonia blieck (1981). p?. arctica elliot & dineley (1983), p?. corniga elliott & dineley (1983), p. leathensis (white, 1935), p. primaeva k i m (1928). p. pygmaea elliott & dineley (1983), p. sartokia elliot & dinely (1983), p. silikrokia elliott & dineley (1983), p . vogti k i m (1928), p . whitei (denison, 1955). protopteraspis micra n. sp figs. 8 and 9. etymology. greek: pi’~p6[, &, b i f . small, refer ring to the very small size of members of this species. holotype. dorsal shield pmo 141.58s141.584 (part and counterpart). paratype. dorsal shield pmo 141.585. from the same locality as the holotype. l o c u s typicus and stratum typicum. hes teskoholmen; wulffberget member of the red bay conglomerate formation. 38 r . r. ilyes et al. fig. 9. reconstruction of protopterusprr micra n . sp. dorsal view of dorsal shield. scale bar = 7 mm; abbreviations: orb, orbital plate: bro. branchial opening; brpl, branchial plate: cpl, cornual plate: ioc. inter-orbital canal; mdc. median dorsal canal. fig. 8. protopteruspis micro n. sp. dorsal view of holotype (dorsal shield). pmo 141.583. 2.7x. diagnosis. small protopteraspid with short, broad, and moderately arched dorsal shield and bluntly rounded rostral plate. orbital plate small, and widely separated from small pineal plate. branchial plate long and curved, expanding pos teriorly t o branchial opening. branchial duct opening dorsally well in advance of postero lateral corner of dorsal shield. cornual plate small and subtriangular with blunt postero-lateral point, ornamentation of fine. sharply crested, dentine ridges with crenulated lateral margins, 8 9/mm. measuremerits. see table 2 . descripori. t h e dorsal disc is oval and gently domed. rostra1 plate broad, short. and bluntly rounded: subrostral area not preserved. orbital plate small: posterior extension unknown. orbital plates extend only a short distance medially towards the pineal plate. pineal plate small and subrounded. branchial plate long, and forming much of t h e lateral margin of the dorsal shield; it is narrow anteriorly, but expands slightly pos teriorly and reaches its maximum width at t h e posteriorly situated branchial opening. t h e bran chial duct opens dorsally well in advance of the postero-lateral corner of the dorsal shield. cor tab(e2. measurements (in m) for proropteruspis micra n. sp. ( ) indicates estimated values. all measurements taken on dorsal shield. n = measured specimens. length dorsal shield: 25-28 ( n = 2) width dorsal shield: l t e 2 l ( n = 2) length dorsal disc: 1%23 ( n = 2) width dorsal disc: l s ( 1 8 ) ( n = 2) lcngth rostral plate: m (n = 2) width rostral plate: %12 ( n = 2) length hranchial plate: 12 ( n = i ) length cornual plate: 5 (n = 1) width cornual plate: 2 ( n = 1) length pineal plate: 1.02 ( n = 1) width pineal plate: 1 (n = 1) length orbital plate: ? length dorsal spine: ? height dorsal spine: ? dentine ridges/mm: b 9 ( n = 2) the downtonian and devonian vertebrates of spitsbergen 39 nual plate small and subtriangular, with blunt postero-lateral point. dorsal spine poorly pre served, but appears to be stout, and laterally compressed. the lateral-line sensory canal system is incom pletely known. the medial dorsal canals diverge and terminate before reaching the inter-orbital canal. the inter-orbital canal forms a “v” shaped loop on the dorsal disc. ornamentation of fine, sharply crested, dentine ridges with crenulated lateral margins, &9/mm. we have decided not to make sem micrographs of the ornamentation as it would mean the destruction of one of the two existing specimens of this species. no specimen of the ventral shield of this species is known. discussion. the important taxonomic charac ters preserved on the dorsal shield indicate that this new form is undoubtedly a representative of the genus protopteraspis. the morphology of the pineal-orbital area and the lateral-line sensory canal system show typical protopteraspid pattern. the pineal plate is widely separated from the orbital plates, and the medial dorsal canals di verge and do not connect with the inter-orbital canal. the inter-orbital canal forms the “v” shaped loop on the dorsal disc typical for the protopteraspids (elliott & dineley 1983). the previously described protopteraspids from spitsbergen are shown in fig. 10. the size and morphology of protopteraspis micra clearly sep arate it from p . v o g i and p. aquilonia. the overall morphology of the new species is quite similar to blieck’s (1981) reconstruction of p. primaeva. a comparison of the new species with the type material of p. prcmaeva shows that the two forms differ in size, p . micra being noticeably smaller. there is also a morphological difference between these two species found in the shape of the con nection between the rostra1 plate and the dorsal disc, and in the shape of the branchial plate and branchial opening. other important morpho logical differences can be found in the shape of the posterior part of the dorsal disc and cornual plate. the noticeable and important morpho fig. 10. previously described protopteraspids from spitsbergen. all from the red bay group. scale bar = 10 mm (from blieck 1984). a = protopteraspis primaeva, b = p . aquilonia, c = p . vogti. v 40 r . r. ilyes et al. logical differences between the two forms indicate for us that p . micro is a species different from p . primaeua. intraspecific variability is known in the pteraspidids, e.g. profopteraspis gosseleti and pteruspis rostrura ( a . blieck pers. commun.), but we feel that the difference in morphology between protoprerapk micra and p . primaeva is too great to indicate intraspecific variability. we feel. how ever, that the two species are closely related. plete specimens of variable size, indicating that there has been little or no size sorting of the fossils. the fossil material has no preferred onen tation. the data suggest that the origin of the fossil material was in or close to the area of deposition, and that the disarticulation of the material was in situ by current action and biogenic activity. age and significance of the invertebrates and palaeoecology vertebrate fauna in addition to the vertebrates, the rock samples early devonian vertebrate faunas of similar over contain bivalves (fig. 11). their preservation is all composition to that found in the wulffberget extremely poor, and the bivalves appear only member of the red bay conglomerate have pre as molds and casts in the matrix. the largest viously been described from the frznkelryggen specimens have a length around 15 mm and width and ben nevis formations (blieck et al. 1987). around 11 mm. no important taxonomic features the wulffberget member fauna has, however, no are preserved, making their determination difspecies in common with the other known verte ficult. the external morphology of the bivalves brate faunas of the red bay group, and their suggests that all t h e individuals belong to modisimilarity is only at the generic level. omorpha? sp. this genus is common in upper an accurate dating of the wulffberget member silurian, lower and middle devonian sandand has been difficult to obtain because the strata siltstones (c. babin pers. comm.). contain no characteristic microfossils useful in this species appears to be a restricted shelly dating. the occurrence of protoptermpis and invertebrate fauna present in the vertebrate-bearanglnspis, two typical early devonian genera in ing strata. no brackish water indicators or normal spitsbergen, suggests an early devonian age for marine indicators have been found in the studied these strata. an early devonian age (loch samples. however, due to a lack of an accurate kovian) for the lower parts of the red bay group sedimentologic log it is not possible to determine was also suggested by murasov & mokin (1979) the depositional environment at the present time. and blieck et al. (1987). murasov & mokin all the studied bivalves are disarticulated, and reported (but did not figure) the occurrence of only one of the cyathaspidid specimens has articutypical early devonian plant fragments from the lated dorsal and ventral shields (pmo 141.575). rabotdalen member of the red bay con the studied fossil material shows, however, no glomerate. this substantiates the early devonian signs of abrasion. the composition of the fossil age on the base of this formation suggested by material ranges from minute fragments to comthe new vertebrates. murasov & mokin (1979) also reported early devonian plants from the base of the type strata of the siktefjellet group on the northern side of liefdefjorden. the new data indicate that the silurian/devonian boundary on spitsbergen is located somewhere below the red bay group, maybe in the siktefjellet group. new field evi dence suggests however, that the murasov & mokin plant locality is actually located in the wulffberget conglomerate, making their age dating somewhat dubious. the correlation of the devonian of spitsbergen to the “classic” anglo-welsh area has been, and still is, quite problematic. blieck et al. (1987) correlated the “psammosteus” horizon of spits bergen with the anglo-welsh pococki zone. the fig zi. crnidentified hivalve, pmo 141.586, 4 . 5 x the downtonian and devonian vertebrates of spitsbergen 41 genera protopteraspis and anglaspis occur together in the anglo-welsh synzondsi zone, but anglaspis is not registered in the pococki zone (blieck & heintz 1979). based on this information it is tentatively sug gested that the wulffberget member at the base of the red bay conglomerate, and then also the base of the red bay group, might also correlate with the anglo-welsh pococki zone. this indi cates that the stratigraphic section between the base of the red bay conglomerate, where the new fauna comes from, and the “psammosteus” horizon is fairly close in time, and that the exten sive lithostratigraphic separation of the two faunas is due to a high sedimentation rate. so far no microvertebrates (thelodonts) or spores have been found in the samples from the wulffberget member to support this hypothesis at the present time. only further collecting can test this hypothesis. acknowledgement. we wish to thank n. heintz, paleon tologisk museum, oslo, for critical reading of the manuscript and h. a . nakrem, paleontologisk museum, oslo, for help with the micrographs. we also wish to thank c. babin, univ ersite claude bernard-lyon 1. france, for help with the bivalves, and a . blieck, universite des sciences et techniques de lille-flandre-artois. france, for conslructive critique. this paper is a contribution t o igcp project 328. references blieck. a. 1981: le genre protoptermpa leriche (vtrtibres, heterostraces) du devonien inferieur nord-atlantique. palaeontographica a 173, 141-159. blieck. a . 1984: les htterostracts ptkraspidiformes; sys ttmatique-phlyog~nie-biostratigraphie-biog~ographie. cahiers de pal6ontologie (section vertebres)> c . n . r . s . edit., paris. 195 pp. blieck. a., goujet, d. & janvier, p. 1987: the vertebrate stratigraphy of the lower devonian (red bay group and wood bay formation) of spitsbergen. modern geol. 11, 197-217. blieck, a . & heintz, n . 1979: the heterostracan faunas in the red bay group of spitsbergen. bull. s o c . geol. de france 7e ser. x x i ( 2 ) , 169-181. blieck. a. & heintz, n. 1983: the cyathaspids of the red bay group (lower devonian) of spitsbergen. the downtonian and devonian vertebrates of spitsbergen. xiv. polar res. 1 n . s . , 49-79. claypole, e . w. 1885: on the recent discovery of pteraspidian fish in the upper silurian rocks of north america. quar. 1. geol. s o c . london 41 (161), 48-64. denison, r. h . 1955: early devonian vertebrates from the knoydart formation of nova scotia. fieldiana: zool. 37. 44%464. denison, r. h. 1964: the cyathaspididae, a family of silurian and devonian jawless vertebrates. fieldiana: geol. 13f.5). 311-473. denison, r. h . 1970: revised classification of pteraspidae with description of new forms from wyoming, fieldiunu: geol. 20, 1-41. elliot, d . k. & dineley, d . l. 1983: new species of pro fopteraspis. j . paleon. 57(3), 474-494. gee, d . 1966: the structural geology of the biskayerhuken peninsula, north spitsbergen. unpublished dissertation. cambridge university. gjelsvik, t . & ilyes, r. r. 1991: distribution of late silurian (?) and early devonian grey-green sandstones in the liefde fjorden-bockfjorden area, spitsbergen. polar res. 9(1), 77 87. jaekel, 0. 1927: der kopf der wirbeltiere. ergebnisse der anatomie urrd eiirwicklurigsgeschichte, 27, 815-974. kirer, j . 1928: the structure of the mouth of the oldest known vertebrates, pteraspids and cephalaspids. palaeobiol. 1 . 117 134. kirer, j . 1932: the downtonian and devonian vertebrates of spitsbergen. suborder cyathaspida. skr. sualb. lshoo. 52. kirer, j. & heintz, a . 1935: the downtonian and devonian vertebrates of spitsbergen. v . suborder cyathaspida. skr. sualb. ishaii. 40. 138 pp. lankester, e. r . 1868: on the discovery of the remains of cephalaspidian fishes in devonshire and cornwall; and on the identity of steganodicfyum m’coy, with genera of those fishes. quart. j . geol. soc. london 15, 41-50. leriche, m. 1924: les “pteraspis” du dtvonien de la belguque. bull. soc. beige gcol., pallontol. d t l y d r o l . 33. 14s-159. murasov, l. s. & mokin, ju. i . 1979: stratigraphic subdivision of the devonian deposits of spitsbergen. pp. 24s261 in winsnes, t. s. (ed.): the geological development of sval bard during the precambrian, lower paleozoic, and devonian. norsk polarinst. skr. 107. white, e . i . 1935: the ostracoderm pteraspis kner and the relationship of the agnathous vertebrates. philos.1 trans. royal soc. london b . 527(225), 381-457. wills, l. j. 1936: rare and new ostracoderm fishes from the downtonian of shropshire. trans. royal soc. edinburgh 58(18), 427-447. woodward. a. s . 1891: catalogue of the fossil fishes i n the british museum (natural history). part ii: elasmobranchii (acanthodii), holocephali, lchthyodorulires, ostrocodermi, dipnoi. and teleostomi (crossopterygii and chondrostean actinopterygii). british museum, london. 567 pp. 26 pp. previous publications in the series “the downtonian and 1. stensio, e . a.:son.: cephalaspidae. a . text, b . plates. skrifter om sualbard og nordirhauet i?. 391 pp. 1927. heintz, a.: acanthaspida. skrifter o m soalbard og lshavet 22. 81 pp. 1929. heintz, a.: acanthaspida. skrifter om soalbard og lshavet 23. 20 pp. 1929. k i z r , j.: suborder cyathaspida. skrifter o m soal bard og lshavet 52. 26 pp. 1932. k i m , j . & heintz, a.: suborder cyathaspida. skrif t o om sualbard og ishavet 40. 138 pp. 1935. heintz. a.: lunaspis-arten aus dem devon spitz bergens. skrifter o m svalbard og ishavet 72. 25 pp. 1937. nilsson, t.: order antiarchi. norges sualbardog lshausunders@kelser skrifter 82. 54 pp. 1941. devonian vertebrates of spitsbergen”: 11. 111. iv. v. vi . vii. 1 2 r . r. i l y s et al. 1x x xi vlii. f q n . s . & heintz. a . the english-norwegian swedish expedition 1y39 geological results. norges .si,alhurdug i~lioi~siiiidersokelser skrrfrer wangsjo. g . morphologic and systematic studies of the spitshergen cephalaspids. a . text. b plates. ,vorti. polarrnsrirrar skrtfrer 97. 653 pp. 1952. heintz. n . : two new species of the genus pferaspis from the wood ba? series in spitshergen. norsk pnlarinsrrtrrrr skrr/rer 11 7. 13 pp. 1960. heintz. n.: giganrasprs-a new genus of fam. pter xi[. 85 5 1 pp 1943. x l l l . x l v . aspidae from spitsbergen norsk polarinsrirurr arbok 1960. 23-27. 1962. heintz. a , : new investigation on the structure of arcrolepis from the devonian o f spitshergen norsk polariiisrrtuff .&hok 1961. 23-40. 1962. heintz. n.: the thelodont sigirrdiu lura n.g., n.sp. from the lower devonian at sigurdfjellet. spits hergen. norsk polarinsrirrrrr .drbok ly70, 112 116. 1970. blieck, a . br heintz. n . : the cyatharpids of thc red bay group (lower devonian) of spits hergen. polar research 1 n s , 15l71. 1yx3. doi:10.3402/polar.v35.20703 r e s e a r c h / r e v i e w a r t i c l e algal biomass and pigments along a latitudinal gradient in victoria land lakes, east antarctica francesca borghini, andrea colacevich, tancredi caruso & roberto bargagli department of physical, earth and environmental sciences, university of siena, via p.a. mattioli, 4, it-53100 siena, italy keywords biodiversity; photosynthetic pigments; proxy; continental antarctica; sediments; biogeography. correspondence francesca borghini, department of physical, earth and environmental sciences, university of siena, via p.a. mattioli, 4, it53100 siena, italy. e-mail: borghini@unisi.it abstract it is generally accepted that antarctic terrestrial diversity decreases as latitude increases, but latitudinal patterns of several organisms are not always as clear as expected. the victoria land region is rich in lakes and ponds and spans 8 degrees of latitude that encompasses gradients in factors such as solar radiation, temperature, ice cover and day length. an understanding of the links between latitudinally driven environmental and biodiversity changes is essential to the understanding of the ecology and evolution of antarctic biota and the formulation of hypotheses about likely future changes in biodiversity. as several studies have demonstrated that photosynthetic pigments are an excellent, although underused, tool for the study of lacustrine algal communities, the aim of the present study was to investigate variations in algal biomass and biodiversity across the latitudinal gradient of victoria land using sedimentary pigments. we test the hypothesis that the biodiversity of freshwater environments decreases as latitude increases. on the basis of our results, we propose using the number of sedimentary pigments as a proxy for algal diversity and the sum of chlorophyll a and bacteriochlorophyll a with their degradation derivatives as an index of biomass. overall, our data show that biomass and diversity decrease as latitude increases but local environmental conditions, in particular, natural levels of eutrophy, can affect both productivity and diversity. to access the supplementary material for this article, please see the supplementary files under article tools, online. according to general ecological principles, biodiversity decreases with latitude as an effect of the harshening of climate: the more extreme the environment in terms of temperature, water availability and feeding resources, the less the terrestrial communities are diverse in terms of species richness and taxonomic composition. despite the recognition of latitudinal diversity gradients (hillebrand 2004), the effect of latitude on biodiversity is mostly known for a very limited number of taxonomic groups, regions and ecosystems. a good example of well-studied cases is vertebrates from terrestrial or marine ecosystems in the northern hemisphere. however, diversity gradients for the northern hemisphere seem not to apply to the southern hemisphere (boyero 2002; vyverman et al. 2007). the determinant of biological diversity is not latitude per se but environmental conditions, which vary with latitude. more than 25 different mechanisms, not mutually exclusive, have been suggested as generating latitudinal diversity gradients, including the history of perturbations, environmental stability, habitat heterogeneity and interspecific interactions, but no consensus has been reached yet (gaston 2000). a recent study concludes that climatic and productivity-related variables tend to be the strongest correlates of species richness (field et al. 2009). across antarctica, many environmental stresses are severe compared to lower latitudes (convey 1996), biodiversity is generally low and ecosystems are simple. several studies showed that many floral and faunal taxa, polar research 2016. # 2016 f. borghini et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 20703, http://dx.doi.org/10.3402/polar.v35.20703 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/20703/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/20703/0 http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/20703 http://dx.doi.org/10.3402/polar.v35.20703 including higher plants, algae, lichens, protozoa and arthropods, become less diverse at higher latitude (smith 1992; broady 1996; wynn-williams 1996). however, even if it is generally accepted that antarctic terrestrial diversity decreases as latitude (and stresses) increases (broady 1996; smith 1996), the latitudinal patterns are not always so clear. in a study conducted along a transect from 548 s (subantarctic) to 828 s (continental antarctica), the highest molecular diversity of cyanobacteria was found in the areas located between 708 s and 808 s, whereas further south and further north from this zone the diversity decreased (namsaraev et al. 2010). only limited support was obtained for a systematic decrease in eukaryotic (primarily fungi, algae and protists) diversity with latitude (lawley et al. 2004; petz et al. 2007), that is, when the comparisons were made between maritime and continental antarctic sites, whereas there was no evidence for a trend of decreasing diversity across the entire range of the maritime antarctic. similar findings were also reported for tardigrades and rotifers (sohlenius & boström 2005) and plants (peat et al. 2007). in the latter study, a diversity gradient was found along the antarctic peninsula, but no such gradient was apparent through victoria land and the transantarctic mountains. the gradient along the antarctic peninsula was clearer for lichens than for mosses, and the cline was driven by an increasing number of species lost from the assemblage with increasing latitude rather than by taxonomically different assemblages being found at different latitudes. moreover, most studies are generally limited to the maritime antarctic and are restricted to measuring macrophyte and animal diversity. relatively little is known about microbial diversity, and just a few investigations of diatoms (maidana et al. 2005) and bacterioplankton (schiaffino et al. 2011) were recently conducted on lacustrine ecosystems across a patagonian�maritime antarctic transect: a decrease of diatom richness and total bacterioplankton abundance with increasing latitude was observed. nowadays, major research efforts on the continent focus on understanding how abiotic variables influence the abundance, richness and fitness of terrestrial animal and vegetation populations, with projects such as the latitudinal gradient project assessing how biodiversity and structure may change with latitude and with climate change. in victoria land, which starts at the darwin glacier (798 s) in the south to cape adare (718 s) in the north, there is a network for monitoring change in vegetation communities to estimate ties with climate change (cannone 2006). the victoria land latitudinal range corresponds to a gradient in factors such as solar radiation, temperature, ice cover and day length, which would be expected to underlie differences in biodiversity (peterson & howard-williams 2000). an understanding of the links between latitudinally driven environmental and biodiversity changes is essential to our understanding of the ecology and evolution of antarctic biota and the formulation of hypotheses about likely future changes in biodiversity. increasing over the last 40 years, limnological research in this region has focused on the study of physical, chemical and biological processes, on the characterization of biotic communities and the basic interactions driving the functioning of aquatic ecosystems (bergstrom et al. 2006). surprisingly, only a few areas of victoria land have been closely investigated, such as mcmurdo sound in southern victoria land (e.g., simmons et al. 1993; vincent et al. 1993; vincent & quesada 1994; hawes & schwarz 1999; nadeau et al. 1999; taton et al. 2006; vopel & hawes 2006). limnological studies in the rest of victoria land have been conducted at only a few sites (guilizzoni et al. 1989; fanzutti et al. 1989; guilizzoni et al. 1992; libera 1993; baudo et al. 2000). more recently, information regarding the physicochemical characteristics of lacustrine waters and sediments has been reported by borghini & bargagli (2004), borghini et al. (2008) and malandrino et al. (2009). these studies showed high diversity in physical, chemical and biological features of lacustrine ecosystems in this region. several studies (hodgson et al. 2004; hodgson et al. 2006; lami et al. 2009; borghini et al. 2011; fernandezcarazo et al. 2013) have demonstrated that photosynthetic pigments are an excellent tool for the study of lacustrine algal communities. however, a challenge in the study of most antarctic lakes is that they show large variations in physicochemical and biological characteristics during spring and summer (borghini & bargagli 2004), implying that reliable evaluations of phytoplankton composition and biomass would require repeated sampling, which the logistical and environmental constraints of antarctic fieldwork make difficult. the aim of the present study was to investigate variations in algal biomass and biodiversity across the latitudinal gradient of victoria land using sedimentary pigments. the starting point of this study is that sedimentary pigments abbreviations in this article bchl a: bacteriochlorophyll a chl a: chlorophyll a hplc: high performance liquid chromatography pca: principal component analysis tn: total nitrogen toc: total organic carbon tp: total phosphorus algal biomass and pigments along a latitudinal gradient in victoria land f. borghini et al. 2 (page number not for citation purpose) citation: polar research 2016, 35, 20703, http://dx.doi.org/10.3402/polar.v35.20703 http://www.polarresearch.net/index.php/polar/article/view/20703 http://dx.doi.org/10.3402/polar.v35.20703 integrate temporal information since sediments are the main sinks for solutes and particulate materials from the lacustrine catchment. moreover, phytoplankton often represent less than 2% of total photosynthetic biomass in polar lakes, and most of the primary production is confined to the phytobenthos (bonilla et al. 2005; rautio et al. 2011). overall, lacustrine sediments serve as temporal and spatial indicators of the entire catchment and are very useful as sentinel systems of environmental and climatic changes (quayle et al. 2002; vincent & laybournparry 2008; leavitt et al. 2009). the total number of pigments was used as an index of diversity, while the sum of chl a and bchl a, with their degradation derivatives, was utilized as biomass index. it should be noted that the use of chl a as an estimate for biomass growth has several limitations as chl a concentrations per cell may vary in relation to light acclimation, nutrient availability and other physiological conditions (anning et al. 2000; kasprzak et al. 2008). however, chl a is often used in ecological studies as a common proxy for biomass dynamics (lizotte 2008). total chl a is often used as a proxy of primary productivity as well (falkowski & raven 1997), assuming that the rate of carbon fixation is positively correlated with the chl a concentration. as rates of pigment degradation can differ greatly among pigments and between lakes with different biotic, physical and environmental features (e.g., leavitt & hodgson 2001), like those of the present study, the sum of chl a, bchl a and their degradation derivatives was chosen as biomass index, instead of chl a alone, in order to integrate possible differences. materials and methods we sampled 48 lakes and ponds, located in 18 ice-free areas, with different lithological features and at different latitudes (spanning about 5 degrees) and altitudes, from kar plateau (76.918 s, 162.548 e) to helm point (72.138 s, 170.158 e). most of the lakes are proglacial and located in rocky catchments with poorly developed soils. they lack outlets, are shallow (maximum depth about 5 m) and have different surface areas (from 10 to 28 630 m 2 , supplementary table s1). study areas and sampling sites are shown in fig. 1, and details of sampling sites and methods have been provided elsewhere (borghini et al. 2011). briefly, surface sediments (1 cm) at a fixed water depth of 20 cm, free of microbial mats, were collected in different points of the littoral zone using a hand corer. the physicochemical features of the water bodies were reported by borghini et al. (2008), and sediment toc, tn and tp by borghini et al. (2011). these parameters are summarized in supplementary table s2, along with the lake ice cover and bird presence, estimated during the sampling. sedimentary pigments were determined by hplc coupled with a photodiode array and a mass spectrometer following the extraction and analytical methods of borghini et al. (2011). fresh sediments were extracted with acetone 90%, utilizing a vortex and a sonicator at low temperature. throughout the extraction procedure, samples were protected from light and high temperature. liquid chromatography�mass spectrometry analysis was performed using a thermo system comprising a finnigan surveyor autosampler, ms pump and ltq. pigments were detected at their maximum wavelength and at their characteristic m/z. peaks were identified by their absorption and characteristic mh � and ms 2 spectra and their elution order by comparing with literature data (e.g., rozema et al. 2002; whitehead & hedges 2002; yuan et al. 2009). their concentrations were determined by comparing hplc peak areas with those of standard solutions prepared with commercially available purified pigments from the international agency for 14 c determination, water quality institute, in hørsholm, denmark (pheophytin a, pheophorbide a, chlorophyllide a, chl c2, chl c3, divinyl chl a, lutein, peridinin, fucoxanthin, violaxanthin, canthaxanthin, zeaxanthin, alloxanthin, neoxanthin, 19’-butanohyloxyfucoxanthin, echinenone, prasinoxanthin, antheraxanthin, diadinoxanthin, 19’hexanoyloxyfucoxanthin, lycopene, myxoxanthophyll) and from sigma aldrich (chl a and b, b,oand b,bcarotene). concentrations of those molecules for which no standard was available were estimated from peak area, assuming specific extinction coefficients for each compound obtained from the literature (hurley & watras 1991; villanueva et al. 1994; jeffrey et al. 1997). where extinction coefficients were not reported or where no structurally or spectrally similar pigments, the coefficient of b-carotene was used (jeffrey et al. 1997). results are expressed as ng g �1 toc because this unit of measurement most accurately captures variations in algal abundance and community composition (leavitt et al. 1997). data analysis prior to multivariate analyses, data and all environmental variables (except ph, ice cover and bird presence, which was estimated in percentage), latitude and longitude were log-transformed to reduce or remove skewness in the data. major patterns of variation in the environmental data were explored using pca, with centring and standardization of the variables. the effects of latitude and environmental variables on the pigment diversity and biomass between sites were f. borghini et al. algal biomass and pigments along a latitudinal gradient in victoria land citation: polar research 2016, 35, 20703, http://dx.doi.org/10.3402/polar.v35.20703 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/20703/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/20703/0 http://www.polarresearch.net/index.php/polar/article/view/20703 http://dx.doi.org/10.3402/polar.v35.20703 investigated also using redundancy analysis. redundancy analysis was performed including both geographic and environmental variables as explanatory variables. the contribution of both environmental variables and geographical (latitude, longitude and distance from the sea) factors in structuring the pigment biomass and diversity was assessed through the use of variance partitioning (borcard et al. 1992). the variance explained by each of these groups allows us to determine the amount of variance in the pigment data that is explained by the environmental data alone, the spatial data alone, by environmental data that is spatially structured, as well as the amount of unexplained variance (borcard et al. 1992). fig. 1 study area and sampling sites. (modified from the antarctic digital database [www.add.scar.org/home/add7] for the coastline and the antarctic geospatial information center, national science foundation, for the ground digital model.) algal biomass and pigments along a latitudinal gradient in victoria land f. borghini et al. 4 (page number not for citation purpose) citation: polar research 2016, 35, 20703, http://dx.doi.org/10.3402/polar.v35.20703 http://www.add.scar.org/home/add7 http://www.polarresearch.net/index.php/polar/article/view/20703 http://dx.doi.org/10.3402/polar.v35.20703 results a total of 132 compounds were detected in lacustrine superficial sediments of victoria land as reported in borghini et al. (2011). pigment indices were correlated by simple ordinary least square linear regression with latitude in order to reveal how key community features such as biomass and diversity may vary with latitudinal environmental gradients. the correlations of these two indices with the latitude were statistically significant and showed a negative slope (respectively r � �0.53 and r � �0.65; pb0.01; figs. 2, 3). the correlation between biomass and latitude was confirmed using the sum of carotenoids and the chl a as indicators of algal biomass. however, a large part of the data variation remained unexplained by latitude, suggesting that other factors affect the two community indices. these results were similar when the analysis was performed without including the derivative forms of pigments and the unidentified compounds and considering just the identified marker pigments (chl a, chl b, scytonemins, fucoxanthin, violaxanthin, canthaxanthin, zeaxanthin echinenone, lutein, b,oand b,bcarotene, myxoxanthophyll, neoxanthin, bchl a; fig. 4). the algal diversity also showed an increasing (statistically significant pb0.01, r �0.7) relationship with biomass (fig. 5). the correlation analyses were also conducted using water and sediment nutrients: tn and tp in the water, toc and tn in the sediments (borghini et al. 2011) as indicators of the trophic status of the lakes, in view of the usefulness of a multidisciplinary approach. the correlations of latitude with these parameters were statistically 70 60 50 40 30 σ ch l a + b ch l a + d e g r 20 10 0 71 72 73 74 latitude 75 76 77 78 pond e fig. 2 biomass (sum of chl a, bchl a and their degradation products, in mg g�1 toc) versus latitude south. fig. 3 total number of pigments versus latitude south. the circle highlights lakes with high nutrient concentrations. fig. 4 total number of identified marker pigments (chl a, chl b, scytonemins, fucoxanthin, violaxanthin, canthaxanthin, zeaxanthin echinenone, lutein, b,oand b,b-carotene, myxoxanthophyll, neoxanthin, bchl a) versus latitude south. fig. 5 species richness (as number of pigments) as function of biomass/ productivity (sum of chl a, bchl a and their degradation products, in mg g�1 toc). f. borghini et al. algal biomass and pigments along a latitudinal gradient in victoria land citation: polar research 2016, 35, 20703, http://dx.doi.org/10.3402/polar.v35.20703 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20703 http://dx.doi.org/10.3402/polar.v35.20703 significant (pb0.05, r � �0.6) and showed a negative slope. because the two pigment-based indices correlated negatively and significantly (pb0.01) with distance from the sea and with altitude, in order to better investigate the relationship with latitude the analysis was repeated selecting just the coastal lakes*within 1000 m of the sea* which were at about the same altitude (the lakes further inland were at a higher altitude). both diversity and biomass indices continued to be significantly (pb0.01) and negatively correlated with latitude, whereas the correlation between the water and sediment nutrients and latitude was negative but not significant when considering coastal sites. pca identified a subset of environmental variables that had a significant influence on pigment diversity and biomass. pca revealed that the main environmental gradient (first ordination axis) is associated with sedimentary tn and bird presence. the second pca axis includes gradients associated with lake latitude, longitude and water conductivity (fig. 6). together, the first two axes capture 45.6% of the total variance. in general, even if no clear cluster is present, it is possible to identify the following groups: (1) edmonson point, lake 13 (code 39), characterized by a 50% ice cover and a big penguin colony around its shores; (2) lakes at 728 latitude (codes 47, 48, 49 and 50), with a partial or total ice cover and with no or few birds; and (3) penguin lagoon (19) and lagoon (25) at inexpressible island, lake e (44) at edmonson point, lake b (38) at gondwana, and the lake of depot island. all these lakes were without ice cover and with birds. redundancy analyses indicated that pigment diversity and biomass were associated with geography (latitude, longitude and distance from the sea), sediment chemistry (tn and toc) and ph (fig. 7). the permutation test performed on all eigenvalues indicated that the above explanatory variables accounted for a significant (999 permutations, pb0.01) portion of pigment distribution variations. employing the two subsets of environmental and spatial variables, we used variance partitioning (borcard et al. 1992) to separate the amount of variance in the pigment data each group could explain. spatial and environmental variables together could account for 67.2% of the variation in pigment diversity and biomass within our study lakes. environmental variation alone accounted for 50.9% of the variation, pure geographical variation accounted for fig. 6 pca of (a) physical and (b) chemical characteristics of lakes. individual ion concentrations were omitted from analysis as all are significantly correlated with conductivity. tns is sedimentary tn. supplementary table s3 provides the identification codes of the lakes. fig. 7 biplot resulting from the redundancy analysis. algal biomass and pigments along a latitudinal gradient in victoria land f. borghini et al. 6 (page number not for citation purpose) citation: polar research 2016, 35, 20703, http://dx.doi.org/10.3402/polar.v35.20703 http://www.polarresearch.net/index.php/polar/rt/suppfiles/20703/0 http://www.polarresearch.net/index.php/polar/article/view/20703 http://dx.doi.org/10.3402/polar.v35.20703 11.1% and the joint effect of geography and environment accounted for 38%. neither the spatial nor the environmental variables considered in the analysis could explain 32.8% of the variation in pigment diversity and biomass. a classical microscopy-based approach to the diversity of algal species in the same lakes in victoria land was carried out using the antadata database (fumanti & cavacini 2005). examining the data in antadata from the limited number of lakes in the present study that have also been investigated in previous studies shows a general increase in species number from granite harbour (11 species, near kar plateau) to inexpressible island (30 species), northern foothills (28 species), gondwana (35 species) and edmonson point (49 species). discussion this study shows that algal biomass and diversity measured by sedimentary lacustrine pigments decrease with increasing latitude, though the effect of environmental variations corresponding to latitude seems to be mediated by local physical and biological conditions. multiple regression models are necessary for a deeper understanding of data variations. for instance, the small pond e at edmonson point (fig. 2) was frequented by skuas that caused eutrophic conditions, explaining this pond’s outlier results. likewise, points within the circle in fig. 3 (lake 14 and lake 15 at edmonson point, gondwana lakes, lago pantano, lagoon at inexpressible island, pozza eneide, depot island, and kar plateau lakes and lake f at mt. murray) had more nutrients than those located at similar latitudes, which may weaken the results from the classical univariate regression. however, even considering the high level of data variance, the negative relationship with latitude seems to be well supported. this is in accordance with previous studies conducted along latitudinal gradients in antarctica. eukaryotic organisms recovered in antarctic soils were influenced by the environmental conditions at each site (lawley et al. 2004), and although bacterial diversity declined with increasing latitude, habitat-specific patterns appeared to be important with complex interactions between location, vegetationand weather-related variables (yergeau, bokhurst et al. 2007; yergeau, newsham et al. 2007). the bacterioplankton composition in a latitudinal gradient of lakes from argentinean patagonia to maritime antarctica was controlled by a combination of spatial (latitude and longitude) and environmental (e.g., phosphate) factors (schiaffino et al. 2011). local diversity generally relates to regional diversity, but local interactions may modify diversity at the community level (stevens & willing 2002). likewise, in a study recently conducted in the united states (stomp et al. 2011), the species diversity of freshwater phytoplankton sampled from 540 lakes and reservoirs displayed strong biogeographical variation. data analysis indicates that these large-scale biodiversity gradients were largely mediated by geographic variation in local environmental factors such as lake productivity (chl a concentration), lake area, lake depth and water temperature. among all of the variables included in this study, chl a had the largest effect on phytoplankton biodiversity. moreover, either a saturating or unimodal productivity diversity relationship was found, as documented in many other studies of terrestrial, marine and freshwater biodiversity (e.g., dodson et al. 2000). lake morphology and conductivity have previously been shown to strongly influence the microbial mat structure and composition in the larsemann hills region (sabbe et al. 2004), bølingen islands (sabbe et al. 2004) and rauer islands (hodgson et al. 2001). in particular, lake water depth was the most important variable explaining pigment composition of the microbial mats, along with turbidity, presumably on account of their impact on the light climate. other variables (such as conductivity and oxygen) were also significant. the influence of conductivity on pigment composition may be related to changes in species composition (hodgson et al. 2004). villaescusa et al. (2010) showed that the trophic status of the lakes of byers peninsula mediates both the abundance and the composition of bacterioplankton assemblages. trophic status, in turn, is regulated both by external inputs from marine fauna and lake morphometry, ice and sediment dynamics. in the lakes of victoria land not only does the trophic status differ between lakes of the same zone but so does the ice cover (supplementary table s2). a study conducted to evaluate the effects on ecosystem structure of ice loss on several meromictic lakes along the northern coastline of ellesmere island showed that chl a concentrations and the relative importance of phytoplankton groups, estimated by photosynthetic marker pigments and microscopy, differed among the studied lakes during the open-water period, implying lake-specific differences in phytoplankton community structure under ice-free conditions. these differences are likely the result of the interplay of many factors including seasonal and interannual variation, catchment and local climatic characteristics, species colonization, nutrient supply and trophic interactions (veillette et al. 2010). a local community is assembled from a regional pool of species, the size and structure of which are influenced by regional processes, including the effects of the geophysical properties of the region, and broad-scale ecological or evolutionary processes such as species migration, f. borghini et al. algal biomass and pigments along a latitudinal gradient in victoria land citation: polar research 2016, 35, 20703, http://dx.doi.org/10.3402/polar.v35.20703 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/20703/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/20703/0 http://www.polarresearch.net/index.php/polar/article/view/20703 http://dx.doi.org/10.3402/polar.v35.20703 invasions and speciation. biogeographical variability is also introduced by differences in historical processes (stevens 2006), for example, how long the bare ground has been exposed to colonization following glacial retreat or changes in sea level. at the last glacial maximum, most present ice-free areas were probably almost entirely icecovered. following glacial retreat, algal communities would have developed from viable propagules deposited on newly exposed substrata, predominantly through long-distance dispersal with wind as a fundamental vector (muñoz et al. 2004). favourable movement of air masses from north to south does occur (wynn-williams 1996). evidence of these transport propagules is provided, for example, by the rare occurrence of exotic mosses in cultures of maritime antarctic soils. however, the wind direction in victoria land is generally from south/south-east (monaghan et al. 2005), with very high speeds recorded during winter, hindering the dispersal of organisms in a southward direction across victoria land. microorganisms may be transported into and around antarctica via air (marshall 1996), ocean currents (murray et al. 1999) and animals (broady & smith 1994). others might have derived from refugia within antarctica and rock exposures that remained ice-free throughout the pleistocene glaciations, for instance, areas of southern victoria land dry valleys (stevens & hogg 2003). palaeolimnological data have demonstrated that some coastal oases of east antarctica hosted terrestrial or freshwater faunas for up to 150 000 years (hodgson et al. 2001). the timing and extent of resource availability (e.g., nutrients and colonizable space) differ across terrestrial habitats, and these differences influence organisms. thus, there are dramatic differences between organisms living a few tens of metres apart (peck et al. 2006). the ice-free areas in antarctica have different sizes, are widely dispersed and can be considered islands surrounded by large areas of uninhabitable environment. like islands, the ice-free areas have peculiar characteristics in terms of isolation and abiotic factors, so differences in assemblage between the ice-free areas are expected either in relation to isolation [the distance of separation could be considered as a surrogate of dispersal rate (conrad et al. 1999)] and size of ice-free areas or because of intrinsic differences in the relevant processes operating in the different sites. in one study, the size of the nunatak and oasis influenced the abundance and taxonomic composition of microfauna in east antarctica (sohlenius & boström 2005). the findings of vyverman et al. (2007) suggest that historical processes constrain global patterns in regional and local diatom diversity, consistent with the theory of island biogeography and metacommunity concepts and probably underlying the endemism observed in the diatom floras in the southern hemisphere. the results of vyverman et al. showed that there are latitudinal gradients in local and regional genus richness in the southern hemisphere. patterns at a regional scale were explained by the degree of isolation of lake districts: the number of locally coexisting diatoms was constrained by the size of the regional diatom pool, habitat availability and the connectivity between habitats within lake districts. as inland water bodies can be considered to be islands within a sea of land (reche et al. 2005) and lakes also show a patchy distribution likely to generate dispersal constraints (barbèran & casamayor 2010), the strong structure we observed in the biogeographic patterns of victoria land lacustrine biota may be the norm in antarctica. conclusions freshwater biomass and diversity measured by sedimentary lacustrine pigments decrease at increasing latitude. the outliers in the regression analysis and pca indicate that the local environmental conditions could dramatically affect both biomass and diversity. the present study confirms that lakes are ideal sentinel ecosystems of environmental conditions. moreover, since spatial (latitude and longitude) gradients are surrogates for temporal changes and can link temporal changes to climate, the study indicates that lakes are early and good indicators of environmental and climatic changes. the chemical approach based on pigment determination is relatively simple and rapid for preliminary studies at large spatial scales. further investigations involving also phytoplankton and more detailed taxonomic approaches are necessary to validate pigment indices in the future. references anning t., macintyre h.l., pratt s.m., sammes p.j., gibb s. & geider r.j. 2000. photoacclimatation in the marine diatom skeletonema costatum. limnology & oceanography 45, 1807�1817. barbèran a. & casamayor e.o. 2010. global phylogenetic community structure and b-diversity patterns in surface bacterioplankton metacommunities. aquatic microbial ecology 59, 1�10. baudo r., barbero p., beltrami m. & rossi d. 2000. chemical composition of the sediment from lake 20 (antarctica). journal of limnology 59, 55�60. bergstrom d.m, convey p. & huiskes a.h.l. 2006. trends in antarctic terrestrial and limnetic ecosystems. antarctica as global indicator. dordrecht: springer. bonilla s., villeneuve v. & vincent w.f. 2005. benthic and planktonic algal communities in a high arctic lake: pigment structure and contrasting responses to nutrient enrichment. journal of phycology 41, 1120�1130. algal biomass and pigments along a latitudinal gradient in victoria land f. borghini et al. 8 (page number not for citation purpose) citation: polar research 2016, 35, 20703, http://dx.doi.org/10.3402/polar.v35.20703 http://www.polarresearch.net/index.php/polar/article/view/20703 http://dx.doi.org/10.3402/polar.v35.20703 borcard d., legendre p. & drapeau p. 1992. partialling out the spatial component of ecological variation. ecology 73, 1045�1055. borghini f. & bargagli r. 2004. changes of major ion concentrations in melting snow and terrestrial waters from northern victoria land, antarctica. antarctic science 16, 107�115. borghini f., colacevich a., caruso t. & bargagli r. 2008. temporal variation in the water chemistry of northern victoria land lakes (antarctica). aquatic sciences 70, 134�141. borghini f., colacevich a., caruso t. & bargagli r. 2011. an update on sedimentary pigments in victoria land lakes (east antarctica). arctic, antarctic and alpine research 43, 22�34. boyero l. 2002. insect biodiversity in freshwater ecosystems: is there any latitudinal gradient? marine and freshwater research 53, 753�755. broady p.a. 1996. diversity, distribution and dispersal of antarctic terrestrial algae. biodiversity and conservation 5, 1307�1335. broady p.a. & smith r.a. 1994. a preliminary investigation of the diversity, survivability and dispersal of algae introduced into antarctica by human activity. proceedings of nipr symposium on polar biology 7, 185�197. cannone n. 2006. a network for monitoring terrestrial ecosystems along a latitudinal gradient in continental antarctica. antarctic sciences 18, 549�560. conrad k.f., willson k.h., harvey i.f., thomas c.j. & sherratt t.n. 1999. dispersal characteristics of seven odonate species in an agricultural landscape. ecography 22, 524�531. convey p. 1996. the influence of environmental characteristics on life history attributes of antarctic terrestrial biota. biological reviews 71, 191�225. dodson s.i., arnott s.e. & cottingham k.l. 2000. the relationship in lake communities between primary productivity and species richness. ecology 81, 2662�2679. falkowski p.g. & raven j.a. 1997. aquatic photosynthesis. malden, ma: blackwell science. fanzutti g.p., finocchiaro f., simeoni u., stefanini s. & taviani m. 1989. reconnaissance of some small lakes near the coast of northern victoria land (antarctica): hydrobiological and sedimentological aspects. bollettino di oceanologia teorica e applicata 7, 17�24. fernandez-carazo r., verleyen e., hodgson d.a., roberts s.j., waleron k., vyverman w. & wilmotte a. 2013. late holocene changes in cyanobacterial community structure in maritime antarctic lakes. journal of paleolimnology 50, 15�31. field r., hawkins b.a., cornell h.v., currie d.j., diniz-filho a.f., guègan j., kaufman d.m., kerr j.t., mittlebach g.g., oberdorf t., o’brien e.m. & turner j.r. 2009. spatial speciesrichness gradients across scales: meta-analysis. journal of biogeography 36, 132�147. fumanti b. & cavacini p. 2005. antadata: a database on biogeography of non-marine algae in continental antarctica. cd-rom. rome: sapienza university of rome. gaston k.j. 2000. global patterns in biodiversity. nature 405, 220�227. guilizzoni p., libera v., manca m., mosello r., ruggiu d. & tartari g. 1992. preliminary results of limnological research in terra nova bay area (antarctica). in r. mosello et al. (eds.): limnology on groups of remote lakes: ongoing and planned activities. pp. 107�120. verbania pallanza: italian institute of hydrobiology. guilizzoni p., libera v., tartari g., mosello r., ruggiu d., manca m., nocentini a., contesini m., panzani p. & beltrami m. 1989. indagine per una caratterizzazione limnologica di ambienti lacustri antartici. (survey of limnological characteristics of antarctic lake environments.) in b. battaglia et al. (eds.): atti del i convegno di biologia antartica. (proceedings of the first meeting on antarctic biology.) pp. 377�408. padua: edizioni universitarie patavine. hawes i. & schwarz a.m. 1999. photosynthesis in an extreme shade environment: benthic microbial mats from lake hoare, a permanently ice-covered antarctic lake. journal of phycology 35, 448�459. hillebrand h. 2004. on the generality of the latitudinal diversity gradient. american naturalist 163, 192�211. hodgson d.a., noon p.e., vyverman w., bryant c.l., gore d.b., appleby p., gilmour m., verleyen e., sabbe k., jones v.j., ellis-evans j.c. & wood p.b. 2001. were the larsemann hills ice-free through the last glacial maximum? antarctic science 13, 440�454. hodgson d.a., roberts d., mcminn a., verleyen e., terry b., corbett c. & vyverman w. 2006. recent rapid salinity rise in three east antarctic lakes. journal of paleolimnology 36, 385�406. hodgson d.a., vyverman w., verleyen e., sabbe k., leavitt p.r., taton a., squier a.h. & keely b.j. 2004. environmental factors influencing the pigment composition of in situ benthic microbial communities in east antarctic lakes. aquatic microbial ecology 37, 247�263. hurley j.p. & watras c.j. 1991. identification of bacteriochlorophylls in lakes via reverse-phase hplc. limnology and oceanography 36, 307�315. jeffrey s.w., mantoura r.f.c. & wright s.w. 1997. phytoplankton pigments in oceanography: guidelines to modern methods. paris: unesco publishing. kasprzak p., padisàkc j., koschel r., krienitz l. & gervai f. 2008. chlorophyll a concentration across a trophic gradient of lakes: an estimator of phytoplankton biomass? limnologica 38, 327�338. lami a., musazzi s., marchetto a., buchaca t., kernan m., jeppensen e. & guilizzoni p. 2009. sedimentary pigments in 308 alpine lakes and their relation to environmental gradients. advances in limnology 62, 247�268. lawley b., ripley s., bridge p. & convey p. 2004. molecular analysis of geographic patterns of eukaryotic diversity in antarctic soils. applied and environmental microbiology 70, 5963�5967. leavitt p.r., fritz s.c., anderson n.j., baker p.a., blenckner t., bunting l., catalan j., conley d.j., hobbs w.o., jeppesen e., korhola a., mcgowan s., ruhland k., rusak j.a., simpson f. borghini et al. algal biomass and pigments along a latitudinal gradient in victoria land citation: polar research 2016, 35, 20703, http://dx.doi.org/10.3402/polar.v35.20703 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20703 http://dx.doi.org/10.3402/polar.v35.20703 g.l., soloveia n. & wene j. 2009. paleolimnological evidence of the effects on lakes of energy and mass transfer from climate and humans. limnology and oceanography 54, 2330�2348. leavitt p.r. & hodgson d.a. 2001. sedimentary pigments. in j.p. smol et al. (eds.): tracking environmental change using lake sediments. pp. 295�325. dordrecht: kluwer academic publishers. leavitt p.r., vinebrooke r.d., donals d.b., smol j.p. & schindler d.w. 1997. past ultraviolet radiation environments in lakes derived from fossil pigments. nature 388, 457�459. libera v. 1993. osservazioni fisico-limnologiche su un lago antartico nell’ambito di una ricognizione dei corpi d’acqua dolce nell’area di baia terra nova. (physical and limnological studies of an antarctic lake as part of a survey of freshwater bodies in the terra nova bay.) in atti del seminario su ‘‘il ruolo delle aree remote nello studio dei cambiamenti globali’’. (proceedings of the seminar ‘‘role of remote areas in the study of global changes.’’) pp. 133�139. rome: italian national research council. lizotte m.p. 2008. phytoplankton and primary production. in w.f. vincent & j. laybourn-parry (eds.): polar lakes and rivers. limnology of arctic and antarctic aquatic ecosystems. pp. 157�178. oxford: oxford university press. maidana n.i., izaguirre i., vinocur a., mataloni g. & pizarro h. 2005. diatomeas en una transecta patagónico-antártica. (diatoms in a patagonian�antarctic transect.) ecologı́a austral 15, 159�176. malandrino m., abollino o., buoso s., casalino c.e., gasparon m., giacomino a., la gioia c. & mentasti e. 2009. geochemical characterization of antarctic soils and lacustrine sediments from terra nova bay. microchemical journal 92, 21�31. marshall w.a. 1996. biological particles over antarctica. nature 383, 680. monaghan a., bromwich d.h., powers j.g. & manning k. 2005. the climate of the mcmurdo, antarctica, region as represented by one year of forecasts from the antarctic mesoscale prediction system. journal of climate 18, 1174�1189. muñoz j., felicisimo a.m., cabezas f., burgaz a.r. & martı̀nez i. 2004. wind as a long-distance dispersal vehicle in the southern hemisphere. science 304, 1144�1147. murray a.e., wu k.y., moyer c.l., karl d.m. & delong e.f. 1999. evidence for circumpolar distribution of planktonic archea in the southern ocean. aquatic microbial ecology 18, 263�273. nadeau t.l., howard-williams c. & castenholz r.w. 1999. effects of solar uv and visible irradiance on photosynthesis and vertical migration of oscillatoria sp. (cyanobacteria) in an antarctic microbial mat. aquatic microbial ecology 20, 231�243. namsaraev z., mano m.j., fernandez r. & wilmotte a. 2010. biogeography of terrestrial cyanobacteria from antarctic ice-free areas. annals of glaciology 51, 1�7. peat h.j., clarke a. & convey p. 2007. diversity and biogeography of the antarctic flora. journal of biogeography 34, 132�146. peck l.s., convey p. & barnes d.k.a. 2006. environmental constraints on life histories in antarctic ecosystems: tempos, timings and predictability. biological reviews 81, 75�109. peterson d. & howard-williams c. 2000. the latitudinal gradient project. report of an antarctica new zealand workshop. christchurch, 15�16 august 2000. christchurch: antarctica new zealand. petz w., valbonesi a., schiftner u., quesada a. & ellis-evans j.c. 2007. ciliate biogeography in antarctic and arctic freshwater ecosystems: endemism or global distribution of species? fems microbiology ecology 59, 396�408. quayle w.c., peck l.s., peat h., ellis-evans j.c. & harrigan p.r. 2002. extreme responses to climate change in antarctic lakes. science 295, 645. rautio m., dufresne s., laurion i., bonilla s., vincent w.f. & christoffersen k.s. 2011. shallow freshwater ecosystems of the circumpolar arctic. ecoscience 18, 204�222. reche i., pulido-villena e., morales-baquero r. & casamayor e. 2005. does ecosystem size determine aquatic bacterial richness? ecology 86, 1715�1722. rozema j., bjorn l.o., bornman j.f., gaberscik a., hader d.p., trost t., germ m., klisch m., groniger a., sinha r.p., lebert m., he y.y., buffoni-hall r., de bakker n.v.j., van de staaij j. & meijkamp b.b. 2002. the role of uv-b radiation in aquatic and terrestrial ecosystems*an experimental and functional analysis of the evolution of uv-absorbing compounds. journal of photochemistry and photobiology b 66, 2�12. sabbe k., hodgson d., verleyen e., taton a., wilmotte a., vanhoutte k. & vyverman w. 2004. salinity, depth and the structure and composition of microbial mats in continental antarctic lakes. freshwater biology 49, 296�319. schiaffino m.r., unrein f., gasol j.m., massana r., balaguè v. & izaguirre i. 2011. bacterial community structure in a latitudinal gradients of lakes: the roles of spatial versus environmental factors. freshwater biology 56, 1973�1991. simmons g.m., vestal j.r. & wharton r.a. 1993. environmental regulators of microbial activity in continental antarctic lakes. in w.j. green & i.e. friedmann (eds.): physical and biogeochemical processes in antarctic lakes. pp. 165� 195. washington, dc.: american geophysical union. smith h.g. 1992. distribution and ecology of the testate rhizopod fauna of the continental antarctic zone. polar biology 12, 629�634. smith h.g. 1996. diversity of antarctic terrestrial protozoa. biodiversity and conservation 5, 1379�1394. sohlenius b. & boström s. 2005. the geographic distribution of metazoan microfauna on east antarctic nunataks. polar biology 28, 439�448. stevens m.i. & hogg i.d. 2003. long-term isolation andrecent range expansion from glacial refugia revealed for the endemic springtail gomphiocephalus hodgsoni from victoria land, antarctica. molecular ecology 12, 2357�2369. stevens r.d. 2006. historical processes enhance patterns of diversity along latitudinal gradients. proceedings of the royal society b 273, 2283�2289. algal biomass and pigments along a latitudinal gradient in victoria land f. borghini et al. 10 (page number not for citation purpose) citation: polar research 2016, 35, 20703, http://dx.doi.org/10.3402/polar.v35.20703 http://www.polarresearch.net/index.php/polar/article/view/20703 http://dx.doi.org/10.3402/polar.v35.20703 stevens r.d. & willig m. r. 2002. geographical ecology at the community level: perspectives on the diversity of new world bats. ecology 83, 545�560. stomp m., huisman j., mittelbach g.g., litchman e. & klausmeier c.a. 2011. large-scale biodiversity patterns in freshwater phytoplankton. ecology 92, 2096�2107. taton a., grubisic s., balthasart p., hodgson d.a., laybournparry j. & wilmotte a. 2006. biogeographical distribution and ecological ranges of benthic cyanobacteria in east antarctic lakes. fems microbiology ecology 57, 272�289. veillette j., martineau m.-j., antoniades d., sarrazin d. & vincent w.f. 2010. effects of loss of perennial lake ice on mixing and phytoplankton dynamics: insights from high arctic canada. annals of glaciology 51, 56�70. villaescusa j.a., casamayor e.o., rochera c., velázquez d., chicote á., quesada a. & camacho a. 2010. a close link between bacterial community composition and environmental heterogeneity in maritime antarctic lakes. international microbiology 13, 67�77. villanueva j., grimalt j.o., de wit r., keely b. & maxwell j.r. 1994. chlorophyll and carotenoid pigments in solar saltern microbial mats. geochemical and cosmochemical acta 58, 4703�4715. vincent w.f., downes m.t., castenholz r.w. & howardwilliams c. 1993. community structure and pigment organization of cyanobacteria-dominated microbial mats in antarctica. european journal of phycology 28, 213�221. vincent w.f. & laybourn-parry j. 2008. limnology of arctic and antarctic aquatic ecosystems. new york: oxford university press. vincent w.f. & quesada a. 1994. ultraviolet radiation effects on cyanobacteria: implications for antarctic microbial ecosystems. in c.s. weiler & p.a. penhale (eds.): ultraviolet radiation in antarctica: measurements and biological effects. pp. 111�124. washington, dc: american geophysical union. vopel k. & hawes i. 2006. photosynthetic performance of benthic microbial mats in lake hoare, antarctica. limnology & oceanography 5, 1801�1812. vyverman w., verleyen e., sabbe k., vanhoutte k., sterken m., hodgson d., mann d.g., juggins s., van de vijver b., jones v., flower r., roberts d., chepurnov v.a., kilroy c., vanormelinger p. & de wever a. 2007. historical processes constrain patterns in global diatom diversity. ecology 88, 1924�1931. whitehead k. & hedges j.i. 2002. analysis of mycosporinelike amino acids in plankton by liquid chromatography electrospray ionization mass spectrometry. marine chemistry 80, 27�39. wynn-williams d.d. 1996. antarctic microbial diversity: the basis of polar ecosystem processes. biodiversity and conservation 5, 1271�1293. yergeau e., bokhorst s., huiskes a.h.l., boschker h.t.s., aerts r. & kowalchuk g.a. 2007. size and structure of bacterial, fungal and nematode communities along an antarctic environmental gradient. fems microbiology ecology 59, 436�451. yergeau e., newsham k.k., pearce d.a. & kowalchuk g.a. 2007. patterns of bacterial diversity across a range of antarctic terrestrial habitats. environmental microbiology 9, 2670�2682. yuan y.v., westcott n.d., hu c. & kitts d.d. 2009. mycosporinelike amino acid composition of the edible red alga palmaria palmata (dulse) harvested from the west and east coasts of grand manan island, new brunswick. food chemistry 112, 321�328. f. borghini et al. algal biomass and pigments along a latitudinal gradient in victoria land citation: polar research 2016, 35, 20703, http://dx.doi.org/10.3402/polar.v35.20703 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/20703 http://dx.doi.org/10.3402/polar.v35.20703 early holocene land floras and faunas from edgeoya, eastern svalbard ole bennike and lars hedenas bennike, 0. & hedenas, l. 1995: early holocene land floras and faunas from e d g e ~ y a , eastern svalbard. polar research 14(2), 205-214. early holocene, near-shore marine sediments from visdalen, edgeaya, eastern svalbard contain locally abundant allochthonous remains of land plants, notably bryophytes. wetland species indicative of mineral rich and calcareous soils are frequent, but upland plants are also well represented. the fossil assemblages are indicative of ecological and climatic conditions similar to those on e d g e ~ y a today. the sediments contain one of the first fossil beetles reported from svalbard. apparently, the modern flora of svalbard was already established in the earliest holocene, probably following immigration from northern europe. a few armeria scabra remains are believed to be derived from interglacial deposits. ole bennike, geological survey of denmark and greenland. thoravej 8, dk-2400 copenhagen nv, denmark; lars hedenas, department of crvptogamic botany, swedish museum of natural history, box 50007, $104 05 stockholm, sweden. introduction apart from exotic driftwood, pre-holocene, quaternary plant remains are rare in svalbard (ingolfsson et al. 1995); however, a number of holocene lake and peat deposits have been inves tigated, mostly by means of pollen analyses. only a few of these go back to the early holocene, and very little is known about the immigration history of svalbard flora and fauna. an exception is the dyarf birch betula nana that seems to have immigrated to central spitsbergen around 6000 i4c years bp (surova et al. 1982). nathorst (1883) was of the opinion that a few hardy species poss ibly survived the last glacial stage on svalbard. but that by far the majority of the vascular plants immigrated after the last ice age via a land bridge joining svalbard and scandinavia. other scien tists, however, find support for the refugium hypothesis ( r ~ n n i n g 1965; odasz 1991; odasz et al. 1991). one argument is that the plants could not immigrate to svalbard after the last ice age because no land bridge connected the archipelago with the european mainland. however, the fact that the small. isolated, volcanic island jan mayen, which has never been connected to any continent by a land bridge, has been populated by 62 species of vascular plants (lid 1964) shows that long distance dispersal of plants does take place across oceans in the arctic. many studies of full and late-glacial phytogeography in northwest europe demonstrate the mobility of plants (birks 1994). palaeoecological studies of early holocene terrestrial/limnic sediments have been carried out by hyvarinen (1968, 1970, 1972). surova et al. (1982), gottlich & hornburg (1982), van der knaap (1989), birks (1991) and wohlfahrt et al. (1995). in addition, there is a find of polytrichum coinrnune hedw. dated at 9870 * 140 years bp (salvigsen & mangerud 1991). surova et al. (1982) obtained a 14c date of 10,360 * 260 years bp (tln-270) on basal peat from reindalen on central spitsbergen. they presented a rather crude pollen diagram from the peat section with only few pollen and spore types from indigenous plants. the oldest peat date appears to come from agardhdalen, western spitsbergen, from where punning et al. (1978) reported a date of 10.570 * 360 years bp (tln-232). van der knaap (1989) obtained a i4c date of 6710 5 80 years b p on basal peat from a section in rosenbergdalen, northwestern edgeoya. both macrofossil and pol len diagrams were published from the site. only macrofossils of s a l k polaris, gramineae and five moss taxa were found in the section, but to this must be added 25 pollen and spore types. van der knaap concluded that the deposit and flora of the former mire indicated that the climate was warmer than today during peat accumulation. palaeoecological studies of lake deposits from svalbard are even fewer than those of peat 206 o l e bennike & l a r s hedenas deposits. hyvarinen (1968. 1970. 1972) studied lake sediments on northern svalbard and b j ~ r n bya by means of pollen analysis. o n e of the sequences from northern svalbard dated back to ca 1oka. but the interpretation of the pollen diagrams is difficult d u e to a high content of long distance transported pollen. birks (1991) presented a detailed macrofossil diagram from lake sediments from s k a r d t j ~ r n a , western spits bergen. the basal sediments were dated by accel erator mass spectrometry ( a m s ) o n s a l k and saxifraga remains to 8 ka. t h e r e is no safe indi cation i n birks' study that any plants arrived after this date. whereas three taxa were found that d o not presently grow in the area. and a mean july temperature about 2°c higher than today was inferred for the early holocene. wohlfahrt et al. (1995) suggested that the mean july temperature on bjsrnoya may have been as much as 4 5 ° c higher than present in the early holocene, based on beetle data. terrestrial plant macrofossils in near-shore marine sediments from adventfjor den, wchtern spitsbergen. were studied by heer (1870) and a n d e r s o n (1910). they found abun dant fruit stones o f e m p e t r u m tiigritm that no longer fruits in this a r e a . the aim of this paper is to describe and inter pret some remains of terrestrial and limnic plants and animals that throw light on the history of svalbard flora and fauna. t h e remains come from sediment samples from visdalen on the north western part of the island of edgeoya, eastern svalbard (fig. 1). a preliminary report on t h e present material that included some tentative moss identifications was published by bennike ( 1992). study area edgeoya covers 5 150 km2 a n d is the largest island in the southeastern part of the svalbard archi pelago; extensive areas are glaciated, although the island is relatively low (norderhaug 1970). t h e bedrock is dominated by triassic sandstone and mudstone with layers of limestones and thin coal seams in places, intruded by some dolerite sills (lock e t al. 1978). t h e northwestern part of the island suppoits the richest vegetation and belongs to the salix polaris zone of brattbakk (1986). large areas a r e virtually barren, but the dwarf shrub s a l i x p o l a r i s is common in favourable sites. ninety-three species of vascular plants a r e known from t h e island (neilson 1970). from the flora and vegetation a mean temperature for the warmest month of around 2°c is suggested for the northwestern part of the island. big. 1 . left. map of sralbard. the a r r o w shows the location of visdalen on edgeoya. right: map of visdalen ahowing thc location of the studied aampleb contour interval 20 rn; contours only showed in visdalen. for detailed description of the sites. see moller er al. ( 1 9 y 5 ) early holocene land floras and faunas from edgegya, eastern soalbard 207 material and methods seven samples were collected during the ponam 1991 expedition to eastern svalbard. for descriptions and interpretations of the sampled sediments, see moller et al. (1992, 1995). the sediment samples consisted of fine sand and silt with allochthonous plant and animal remains, some of which were well preserved, indicating short transport. the samples were wet-sieved through 0.42 and 0.21 mm sieves, and the residue left on the sieves was sorted under a dissecting microscope. most of the bryophyte remains were well pre served, which made it possible to identify a large proportion of the material to a taxonomic level where a partial reconstruction of the paleo environment becomes possible. the bryophyte material is deposited in the department of cryp togamic botany, swedish museum of natural his tory (no. 520644-620650). the other material is housed in the geological museum, copenhagen. the bryophyte nomenclature follows corley et al. (1981), with additions in corley & crundwell (1991) except for brachytheciurn coruscum i . wag. ( b . g r o e n l a n d i c q ) , polytrichastrum alp inum (hedw.) g . l . sm. (polytrichum alpinum). p . sexangulare (brid.) g. l. sm. (popytrichum sexangulare), pseudocalliergon angustifoliurn hedenas (hedenas 1992b), p . trifarium (web. & mohr) loeske (calliergon trifarium), p . tur gescens (t. jens.) loeske (scorpidium turges c e n s ) , scorpidium cossoni (schimp.) hedenas (drepanocladus cossoni) . straminergon stram ineum (brid.) hedenas (cal[iergon slramineum) and warnstofia sarmentosa (wahlenb.) hedenas) (calliergon sarmentosum). tracheophyte nomenclature follows ronning (1979). identification seeds of melandrium apetalum were identified from their wing which is broader than that of the related species m . angustiflorurn, but the seeds only measured about 1.2 mm across. it is impos sible to make species identification of armeria maritima s.1. calyces (godwin 1975). but from phytogeographical considerations the taxon represented must be one of the northern taxa that include armeria arctica wallr., a . maritima (mill.) willd. subsp. arctica (cham.) hult., a . scabra pall.. a . labradorica wallr. and a . sibirica turcz. we use the name a . scabra which is the one currently in use in greenlandic botany (bocher et al. 1978). it is possible that some of the seeds referred to draba sp. represent other brassicaceae genera. all s a l k remains (leaves, bud scales, fruit capsules, bark and wood) are referred t o salix polaris, t o which the diagnostic leaves belonged, and which is the only willow species presently growing on edgeoya. tar axacum achenes were similar to taraxacum bra chyceras achenes which have smaller spines than t . arcticum (trautv.) dahlst. achenes, the only other taraxacum species on e d g e ~ y a today; but if the achenes are interglacial in age the species identification becomes uncertain. lepidurus was represented only by apodous segments. for climatic reasons the remains are referred to lepidurus arcticus. olophrum was represented by one elytron and possibly a tergite. the elytron can not be identified at the species level, but since 0. boreale is the only species recorded from svalbard at present (fjellberg 1983), the fossil elytron has been referred to this species (j. bocher, pers. comm. 1992). results and discussion non bryophytes identified land and freshwater plants and animals are listed in tables 1 and 2 and some remains are illustrated in fig. 2. the samples were small (table l ) , but nevertheless some of the assem blages are diverse. samples 87711. 87728 and 86251 contained marine fossils, showing that these assemblages were deposited in shallow water mar ine environments, probably near the mouth of a river. the marine fossils comprise the following animal groups: foraminifera, hydroids, serpulids. ostracodes, barnacles, malacostracans, molluscs, echinoids, bryozoans and fishes and the brown algae sphacelaria sp. and laminaria sp. i n this context it should also be noted that the oribatid mite ameronothrus lineatus, which occurred in similar samples not included in table 1, lives at or near the sea shore (hammer 1944). the other assemblages derive from lagoon sediments (88203) and glacio-lacustrine sediments (88651, 88655 and 86266) (moller et al. 1995). the radiocarbon dates range from 12.5 ka to 8.5 ka (table 3). the 12.5 ka date on sample 87711 does not date the time of sedimentation 208 ole bennike & lars hedenas tablr i macrofossils (except brlophytes) from edgeoya. svalbard sample no. 87711 87728 88203 8625 i 86266 8865 i 88655 c-14 age ( k a ] ' localit! sample rire (liter) plants: cenococcuni geoplirlum fries ?pyrenomycetidar equrrerurn sp r a n u n ~ i i l i ~ ~ sulphiirruj sol. ranunculus sp papauer dalilrancitn nordh melandrrum aprrnluni fenzl crrusrrunr arcricurn/aipiniitn minrinrrru rubella ( w b g . ) hiern silene ucuulr ( l . ) jacq o x v r r u d i p r i a ( l ) hill p o l ~ g o n i m iriviparuni l arrnerra ,i.ahra pall. draba sp salrx polarrs wg porenrillu \p saxrfrugo opporrrrfolru l dryas ocruperaln l turnxaciim h r a c h y c e r a dahlrt j u n c i f i sp care.< \pp. animals. lrpiduric\ urcricu$ pallas daphnra p d e r dc gcer t!pe oluphnrrn horrale (pa! kull) 91chneumonidae chironoinidae ?lepidoptera errgone 5p orihalida lu;rrlu 5p candona \p. 12 5 >9 8 10 u 9 9 1806 1715 1804 181 1 n s 0.35 0.1 0 7 8.6 8.7 8.5 1810 2103 2103 1.0 0.2 1.1 + + + + + + 1 + + + 1 3 + + + + + + + + + + + i t + + + + + + + + + + + + + + + + +! a + i + r r l a t n e frequent) 1-5 absolute nurnberc 'the radiocarbon dates are presented in table 3 since the sample is underlain by in situ shells dated at 9 . 4 k a (the sea water corrected age is 9.oka) (moller et al. 1995). t h e dated sample must therefore consist of older plus younger material. sample 87728 lies just under in situ shells dated t o 9.7 ka (table 3 ) . t h e samples with plant remains contained numerous small coal particles. and also a few pre-quaternary trilete megaspores which could not b e identified due to their simple morphology, but which are probably of mesozoic age ( s . b . m a n u m , pers. comm. 1991). it is possible that previously published peat and gyttja dates based o n bulk samples from t h e region are t o o old d u e to contamination by coal particles. but o n the other hand bulk peat samples may also be t o o young d u e to contamination by intruding roots. t h e assemblages are indicative of high arctic biotas similar t o those on edgeoya today. all vascular plants listed grow on edgecbya today, except o n e , namely armeria scabru. which does not occur o n svalbard a t present. from its modern geographical range (fig. 3), there seems to be n o climatic reason for this since t h e plant grows in north greenland and northernmost canada where the climate is similar to that of svalbard. because t h e radiocarbon date shows that the sample from the same location from which the arnicria remains come includes some old plant material, it is possible that the arrneria remains early holocene land floras and faunas f r o m e d g e l y a , eastern soalbard 209 table 2. bryophytes from edgetiya. s = shoot; €3 = branch; l = leaf. sample no. 87711 87728 88203 86251 86266 88651 88655 amblystegium subg. aulacomnium palustre a . turgidum brachytheciurn coruscum b . turgidum bryoeryrhrophyllum recuroirostrum bryum cf. pseudotriquerrrtnr bryum sp. calliergon cf. richardsonii c. giganreurnlrichardson;; c. richarhonii campylium polygamum campylium sp cerarodon purpureus dichodontium pellucidum distichium sp. dirrichuni pexicaule drepanocladus s.str. s p . encalypta alpinn e. proceralsrreptocarpa encalypta sp. isopterygiopsis pulchella lophoria s.1. sp. oncophorus wahlenbergii cf. orthothecium sp, paludella squarrosa philonotis fontanalromentella philonoris s p . pogonarum dentaturn p. urnigerum pohlia wahlenbergii pohlia sp. polytrichastrum alpinum p. sexangulare polytrichum juniperinumlstricrum polytricum sp. polytrichumlpolyrrichastrum sp. polytrichaceae s p pseudocalliergon atigusrifolium p. turgescens racomitrium canescenrlpanschii racomitrium sp. sanionia nioalis s. uncinara scorpidium cossoni s. scorpioides sphagnum squarrosumlreres timmia austriaca t. noruegica timmia sp. tomenrypnunr nilens warnstorfia sarmenrosa w . tundrae indet. indet. amblystegiaceae indet. acrocarp lndet. pleurocarp hygroamblystegium s p . *of these, 18 and 5 shoots, respectwely, were found in coherent tufts '"of these, 5 shoots were found in one coherent tuft. * * t a l y p t r a e . 210 ole bennike & lars hedenas tuhle 3 a m s radiocarbon dates. for details of sediments and stratigraphv. see moller e l al. (1992. 1995). loc. sample altitude n o no m a s l . lab no age yrs bpi dated material 12470 ? 250 plant remains 1806 8771 1 19.8 aar-846 1806 x77122 19.6 aar-839 8960 ? 140 mya truncata 1715 87721' 32.6 aar-842 9710 ? 160 mva truncatu 1x01 w o 3 51.0 aar-847 9965 ? 190 plant remains 1811 86251 67.0 aar-843 9475 ? 220 plant remains4 2 103 8865 1 50.8 aar-834 8690 -t_ 250 plant remains 1610 86266 52.0 aar-844 8640 ? 170 plant remains 2103 88655 47.1 aar-833 8530 -t 190 plant remains 'the dates have been corrected for isotopic fractionation by normalising to b"c = -25% p d b . samples 87712,87721, and 86251 have becn corrected f o r a marine reservoir age by subtracting 440 vears (mangerud & gulliksen 1975). 'sample x7712 lies just below 87711 'sample x7721 lies just above 87718. 'remains of marine plants. are derived from interglacial sediments, in spite of the fact that they are well preserved. armeria calyces are known from last interglacial deposits i n central eastern greenland (bocher & bennike 1991) and in northwestern greenland (bennike & bocher 1992): in addition, there is an undated northern extralimital occurrence from the eastern part of northern greenland (bennike unpubl.). the turaxacum achenes are another possible interglacial candidate since none of the other samples contained this taxon: but as the plant grows on e d g e ~ y a today. the achenes may also be holocene. the rove beetle olophritm boreale has been collected at woodfjorden, northern spitsbergen and on bjsrnoya (fjellberg 1983) and may well be a member of the extant fauna of e d g e ~ y a . it has also been recorded from holocene lake sediments on b j s r n ~ y a (wohlfahrt et al. 1995). olophrum boreale is a widely distributed northern holarctic species although it has not been found in greenland (campbell 1983: bocher 1988). no limnic plants were found. but a few remains of the limnic animals lepidurus, daphnia and candonu indicate that ponds w i t h mesotrophic waters existed in the area. brvophytes many of the bryophytes (table 2 ) indicate cal ciumor mineral-rich conditions. this is what would be expected in a penglacial environment or in an area where the ice has recently retreated (cf. miller 1987), but the bedrock of the area probably also favours calciphiles. wetland species are often common in fossil bryophyte assemblages (e.g., janssens 1983; dickson 1973. 1986; hedenas 1992a; 1995) and in the present samples pseudocalliergon turgescens, scorpidium cossoni and tomentypnum nitens, all occurring in mineral-rich t o calcareous wetland habitats today, were frequent. other species of more or less mineral-rich to calcareous wetlands include brachythecium turgidum, calliergon spp., campylium polygarnurn, campylium s p . , scor pidium scorpioides. warnsto@a tundrae and pseudcalliergon angustifolium. the last species was recently described (hedenas 1992b) and is known from only one extant svalbard locality, on b j o r n ~ y a (frisvoll & hedenas unpubl.). in the scandinavian mountain range i t occurs mainly in moderate late snow beds in calcareous areas, but it occurs also in calcareous fens in the northern boreal zone in finland. this species is otherwise known from iceland, northern north america and the chukotskiy polustrov in easternmost rus sia (hedenas unpubl.). aulacomnium turgidum and a . palustre are also found in wetlands or on wet heaths, but these species are also found in intermediate ( a . turgidurn) or mineral-poor habitats ( a . palustre). spring-influence or moving water is indicated by paludella squarrosa, phi lonotis sp.. pohlia wahlenbergii and warnstorfia sarmentosa. all these taxa are found in inter mediate to rather mineral-poor places. finally. some of the taxa found indicate probable nutrient enrichment (nand pcompounds), namely cal liergon s. str. spp. (i.e., excluding pseudo calliergon trifarium, warnstorfia sarmentosa, straminergon stramineum), campylium polyga early holocene land floras and faunas f r o m edgelya, eastern svalbard 21 1 fig. 2 . sem photographs of selected vascular plant macrofossils from edgeoya. a-b. armeria scabra calyces. c-d. taraxacum brachycerar achenes. e . melandrium apetalum seed. f . ranunculus sulphurem achene. the figured specimens (mguh 21272 21677) are deposited in the type collection of the geological museum, copenhagen. scale bars = 1 m m . m u m , drepanocladus s . str. sp., sphagnum squarrosumlteres and warnstoijia tundrae (based on kooijman 1993, van wirdum 1991, hedenas & kooijman unpubl. data, and own (hedenas) extensive field-work in northern europe). many of the terrestrial taxa are found today in more or less open (i.e., with sparse cover of vascular plants) and unstable environments. examples include cerutodon purpureus, pogon atum dentatum, p . urnigerum, polytrichastrum alpinum, p . sexangulare (often in late snow beds) and racomitrium canescenslpanschii. these taxa are either indifferent as regards the mineral content, or occur in relatively mineral-poor habi tats, whereas dichodontium pellucidurn and tim mia norvegica indicate somewhat richer and wetter environments. brachythecium coruscum, bryoerythrophyllum recuruirostrum, distichium sp., ditrichum pexicaule, encalypta spp., isop terygiopsispulchella and timmia austriaca all indi cate mineral-rich habitats and can be found both on somewhat disturbed soil (often in crevices or when the soil surface is uneven) and in rock crevices in both dry and wetter situations. 212 ole bennike & lars hedeniis ha 3. (‘ircumpolar map showing the modern geographical range of northern armerra taxa (armerra arcfica. a . scabra. a . lubradoricu. a . sibiricu. a . maririma). based on hiltcn & fries (1986) the arrow indicates the fossil locality. saninnia uncinata occurs in a wide range of habitats in northern and arctic areas. on the other hand, s. niualis is a species of extreme late snow bed habitats or it may also grow along meltwater brooks from large late snow beds and glaciers. in europe. this species is at present known from northern mountainous areas, where i t is found mainly in the middle and high alpine regions and in the arctic, including svalbard (hedenas 1989). i t is now aiso known from three northern north american and greenland localities (hedenas unpubl.). but since the species was described rather recently (hedenas 1989). andsince it seems to be common i n its northern european dis tribution area. one would suspect that i t is widely distributed in the arctic. the find of rmblysregiitrn subg. hygroarn hlwtegiitnz is interesting. the shoot resembles atnblystegium fliwiatile. a species that is not very likely to be found in arctic areas. however. since the material does not permit identification to the species level. inferences regarding the habitat should not be made from this find. this shoot rnav derive from interglacial deposits. taken together. the bryophytes found indicate mineral-rich environments, with a well-developed wetland flora. the wetlands were probably sur rounded by somewhat unstable dry ground. where large areas had a rather sparse cover of vascular plants. the upland plants may also (partly) reflect the environmental conditions some distance away from the wetlands. possible means of transport include flowing water and wind. the assemblage is similar t o what can be found in svalbard (kuc 1963; philippi 1973; elvebakk 1982) or at high altitudes on mineral-rich scandinavian mountains today, and indicates that the climate was probably similar to that in these environments today. conclusions many of the plant and animal taxa reported are new to the fossil flora and fauna of svalbard, but this mostly reflects the few studies of quaternary macroscopical terrestrial plant and animal remains that have been carried out. in addition, nearly all records are the oldest known from svalbard. one of the results of this study is the possibility of finding interglacial plant remains on north western edgeaya, certainly not the most prom ising area of svalbard to search for such remains considering that pre-holocene quaternary deposits are almost unknown from this island (landvik et al. 1995). the data also show that the present flora, and the range of habitats and plant communities of svalbard, were already well estab lished in the earliest holocene. we are inclined to follow nathorst’s view that only few vascular plants survived the weichselian glacial maximum on svalbard because most lowland areas were glaciated (mangerud et al. 1992) and because the climate was colder than at present. if this is the case. the major part of the flora must have immi grated in the latest part of the weichselian. many radiocarbon dates between 13 and 10ka from western spitsbergen show that some areas were deglaciated by then (mangrud et al. 1992). deglaciation of lowland areas on edgeoya began about 10.3 ka bp (landvik et al. 1995). it should also be pointed out that virtually no clear endemic species occur on svalbard. a fact which also tes tifies to the young age of the flora. acknowledgements. we thank c . kronborg and 0. stubdrup. university of aarhus and p . moller, univcrsity of lund. who made the samples available for the analyses. j . bocher, zoologi cal museum, denmark, kindly identified insect and spider remains. and provided information o n ohphrum. j . landvik and two anonymous referees provided constructive criticism o f the manuscript early holocene land floras and faunas f r o m e d g e ~ y a , eastern svalbard 213 references anderson. g . 1910: die jetzige und fossile quatarflora spitz bergens als zeugnis von klimaanderungen. pp. 409-417 in posrglaziale klimaueriinderungen. stockholm. bennike, 0. 1992: early holocene terrestrial plants and animals from edgeeya, eastern svalbard. lundqua rep. 35,139-144. bennike, 0. & bocher. j . 1992: early weichselian interstadial land biotas at thule, northwest greenland. boreas 21, 111 117. birks. h. h. 1991: holocene vegetational history and climatic change in west spitsbergen plant macrofossils from skardtjarna. an arctic lake. the holocene i , 2 w 2 1 8 . birks, h. h. 1994: plant macrofossils and the nunatak theory of per-glacial survival. pp. 12f143 in lotter, a . f. & ammann. b. (eds.): festschrift gerhard lang. dissertariones boranicce 234. bocher, j. 1988: the coleoptera of greenland. medd. grpn land biosci. 26. 100 pp. bocher, j. & bennike, 0. 1991: interglacial land biotas of jameson land, east greenland. lundqua rep. 33, 129 136. bocher. t . w . , fredskild, b . , holmen, k. & jacobsen, k. 1978: gr@landsflora. p. haase & sen, copenhagen. 327 pp. brattbakk, i . 1986: vegetatjonsregioner sualbard og jan maven. statens kartverk, hdnefoss (map). campbell, j. m. 1983: a revision of the north american omaliinae (coleoptera: staphylinidae). the genus olophrum erichson. can. ent. 115. 577-622. corley, m . f. v. & crundwell, a . c. 1991: additions and amendments to the mosses of europe and the azores. j . bryol. 16, 337-356. corley. m. f. v . , crundwell. a . c . , dull, r., hill, m . 0. & smith, a. j . e . 1981: mosses of europe and the azores; an annotated list of species, with synonyms from the recent litterature. j . bryol. 11, 609-689. dickson. j. h. 1973: bryophyres of the pleistocene. cambridge university press. cambridge. 256 pp. dickson, j. h . 1986: bryophyte analysis. pp. 627-643 in berglund, b . e . (ed.): handbook of holocene palaeoecology and palaeohydrology . john wiley & sons, chichester. elvebakk. a . 1982: geological preferences among svalbard plants. inter-nord 16, 11-31. fjellberg, a . 1983: three species of staphylinid coleoptera new t o spitsbergen. fauna noruegica serie b 30, 110-111. godwin, h . 1975: the hisrory of the bririrh porn. cambridge university press, cambridge. 541 pp. 2nd ed. gottlich, k . & hornburg, p. 1982: ein zeuge warmezeitlicher moore im adventdalen auf spitsbergen (svalbard-archipel). telma 12, 253-260. hammer, m. 1944: studies on the oribatids and collemboles of greenland. medd. grpnland 141 ( 3 ) . 210 pp. hedenas, l. 1989: the genus sanionia (musci) in northwestern europe, a taxonomic revision. ann. bot. fennici 26, 399 419. hedenas, l. 1992a ["1990']: a subfossil find of pseu docalliergon breuifolium in northern sweden. lindbergia 16, 150-152. hedenas, l . 1992b ["1990"]: the genus pseudocalliergon in northern europe. lindbergia 16, 80-99. hedenas, l. 1995 y1994"l: environments indicated by bry ophytes in early weichselian interstadial deposits from north ern sweden. lindbergia 19, 87-105. heer, 0. 1870: die miocane flora und fauna spitzbergens. k . suenska vet. akad. handl. 8 (7). 23-24. hyvarinen, h . 1968: late-quaternary sediment cores from lakes on bjorneya. georgr. ann. 5 0 a . 235-245. hyvarinen, h . 1970: flandrian pollen diagrams from svalbard. geogr. ann. 52a, 21s222. hyvarinen, h. 1972: pollen-analytical evidence for flandrian climatic change in svalbard. pp. 225-237 in vasari, y . , hyva rinen, h. & hicks, s . (eds.): climatic changes in arctic areas during the last ten-thousand years. acra unioersiraris ouluenris, series a, scientiae rerum nacuralium no. 3 , geo iogica no. 1 . hultbn, e. & fries, m. 1986: arlas of north european vascular plants 1-111. 1172 pp. koeltz scientific books, konigstein. ing6lfsson. 0.. rognvaldsson, f., bergsten, h . , hedenas. l.. lemdahl. g . & lirio, j . m. 1995: late quaternary glacial and environmental history of kongsoya, svalbard. polar res. 14(2), 123-139. janssens, j. a. 1983: past and extant distribution o f dre panocladus in north america, with notes on the dif ferentiation of fossil fragments. j . hattori bot. lab. 54.251 292. kooijman, a . m. 1993: on the ecologlcal amplitude of four mire bryophytes; a reciprocal transplant experiment. l m f bergia 18, 1 s 2 4 . kuc. m. 1963: flora of mosses and their distribution on the north coast of hornsund (s.w. svalbard). fragm. flor. geobot. y. 291-366. landvik, j . y., hjort, c., mangerud, j . . moller, p. salvigsen, 0. 1995: the quaternary record of eastern svalbard an overview. polar res. 14(2). 95-103. lid, j . 1964: the flora of jan mayen. norsk polarins!. skr. 130. 107 pp. lock, b. e., pickton, c. a . g . , smith, d. g.. batten. d. j . & harland. w. b. 1978: the geology of edgeclya and barentseya, svalbard. norsk polarinsr. skr. 168. 64 pp. mangerud, i. & gulliksen, s . 1975: apparent radiocarbon ages of marine shells from norway. spitsbergen. and arctic canada. quat. res. 5, 26?-273. mangerud, j . , bolstad, m . , elgersma, a . , helliksen, d.. land vik, j . y . . lenne, i . . lycke, a . k., salvigsen, 0.. sandahl. t. & svendsen. i. i . 1992: the last glacial maximum on spitsbergen, svalbard. quar. res. 38. 1-31. miller. n. g. 1987: late quaternary fossil mossflorasof eastern north america: evidence of major floristic changes during the late pleistocene-early holocene transition. svmp. biol. hungarica 35, 34s360. moller. p . , kronborg, c . . johdnsson. k. & stubdrup. 0. p. 1992: the quaternary history of visdalen, edgeaya. eastern svalbard. lundqua rep. 35, 85-130. moller, p . , stubdrup, 0. p. & kronborg, c. 1995: late weich selian to early holocene sedimentatin in a steep fjord/valley setting. visdalen, e d g e ~ y a , eastern svalbard: glacial deposits, alluvial/colluvial-fan deltas and spit-platforms. polar res. 14(2), 181-203. nathorst, a . g . 1883: nya bidrag till kannedomen om spets bergens karlvkxter, och deres vaxtgeografiska forhillan den. kgl. suenska verensk. akad. handl., ny foljd 20(61. 88 pp. neilson, a . h . 1970: vascular plants of edgeeya, svalbard. norsk polarinst. skr. 150. 71 pp. norderhaug. m. 1970: investigations of the svalbard reindeer (rangifer rarandur platyrhynchur) in barentsdya and edgeeya, summer 1969. norsk polarinsf. arbok 1969. 70 79. odasz, a . m . 1991: distribution and ecology of herbaceous pedicularis dasynrha (scrophulariaceae) in spitsbergen, sval 214 ole bennike & lars hedenas bard archipelago: relation to present and past environments striae 34. 145-152 odasz. a. m., karkkainen. k., muona. 0. & wein. g. 1991: genetic distances between geographically isolated pediculark dasyantha populations in spitsbergen. svalbard archipelago. n o w a y . evidence of glacial survival? norsk geol. tidssk 71. 21%221. philippi. g . 1973: moosflora und moosvegetation des freeman sund-gebietes (shdost-spitsbergen). ergebnirsc der stuuf erland-expedition 7. 83 pp. punning, j . m.. rajamae, r . & ehrenpreis. m. 1978: tallinn radiocarbon dates v. radiocarbon 20. 4 6 1 4 . r ~ n n i n g . 0. i . 1965: et bidrag ti1 forstielsen av de arktiske planters historie p i svalbard trondheim, aktietrykkeriet 1 trondheim. 20 pp. rsnning. 0 1. 1979. soulbards flora. norsk polarinstitutr. salvigsen. 0 . & mangerud. j . 1991: holocene shoreline dis placement at agardhbukta. eastern spitsbergen. svalbard polar res. 9. 1-7. oslo. 128 pp surova, t . g . . troickij. l. s. & punning, ja.-m. k. 1982: o b istorii oledenenija spicbergena v golocene po dannym paleobotanieeskich issledovanij (on the history of the hol ocene glaciation of spitsbergen in the holocene from data of palaeobotanical investigations). marerialy gljaciologifeskich hsledouonjj. chronika, obsuidsniju (materials of glaci ological investigations. chronicle, discussions) 42, 100-106 van der knaap. w. 0. 1989: past vegetation and reindeer on edgeeya (spitsbergen) between c. 7900 and c. 3800 bp, stud ied by means of peat layers and reindeer faecal pellets. j . biogeogr. 16, 379-395. van wirdum. g . 1991: vegetation and hvdrology of flootirig rich-fern. datawyse, maastricht. wohlfahrt, b . , lemdahl, g . , olsson, s., persson, t . , snowball, i. & jones, v. 1995: early holocene environment on bjar n ~ y a (svalbard) inferred from multidisciplinary lake sediment studies. polar res. 14(2). 253-275. 1 supplementary material for: pedersen å.ø. et al. 2022. five decades of terrestrial and freshwater research at ny-ålesund, svalbard. polar research 41. correspondence: åshild ønvik pedersen, norwegian polar institute, fram centre, po box 6606 stakkevollan, no-9296 tromsø, norway. e-mail: aashild.pedersen@npolar.no. supplementary table s1. overview of long-term monitoring time-series (> 10 years), newly established data series that will be run in a longterm monitoring perspective and studies that can be used as a basis to build future long-term time series obtained at the ny-ålesund research station. monitoring targets are listed alphabetically under each ecosystem component. ecosystem component monitoring target spatial extent methods starting year interval responsible institution references a climate and weather active layer temperature and moisture, permafrost temperature kolhaugen b observational 2016 1 min. university of insubria, italy christiansen et al. 2019 ground surface temperature brøggerhalvøya sarsøyra observational 2012 annual norwegian polar institute c pedersen unpubl. data snow depth and basal ice brøggerhalvøya observational 2000 annual norwegian polar institute c hansen, pedersen et al. 2019, peeters et al. 2019 soil temperature, snow cover kolhaugen b observational 2018 1 min., 1 hour national research council, italy salzano et al. 2016 mailto:aashild.pedersen@npolar.no 2 ecosystem component monitoring target spatial extent methods starting year interval responsible institution references a climate and weather standard meteorological parameters ny-ålesund observational 1961, 1963d daily norwegian meteorological institute standard meteorological parameters ny-ålesund observational 1993 1 min. alfred wegner institute, germany maturilli 2020b, maturilli et al. 2013 standard meteorological parameters zeppelin mountain observational 1998 1 hour norwegian institute for air research www.nilu.com/facil ity/nilusobservatories-andmonitoringstations/zeppelinobservatory/ standard meteorological parameters, net radiation components, snow depth, snow temperature, albedo kolhaugen b observational 2009 1 min. national research council, italy mazzola et al. 2016 standard meteorological parameters, snow water equivalent, active layer, temperature, moisture, permafrost temperature bayelva observational 1998 1 hour alfred wegner institute, germany boike et al. 2018 3 ecosystem component monitoring target spatial extent methods starting year interval responsible institution references a climate and weather surface net radiation components ny-ålesund observational 1992 1 min. alfred wegner institute, germany maturilli et al. 2015, maturilli 2020a uv spectral radiation ny-ålesund observational 2007 15 min. national research council, italy petkov et al. 2019 water temperature, light penetration, ph, presence of ice/water, snow cover solvatnet observational 2016-18 1 min. 1 hour sapienza university, italy pasquali unpubl. data soil processes bacteria, soil ph, organic carbon midtre lovénbreen observational 2014 irregular korea polar research institute tripathi et al. 2018 bacterial community structure, soil physicochemical properties midtre lovénbreen observational 2012 irregular korea polar research institute kim et al. 2017 functional genes along spatial and temporal gradients knudsenheia, ossian sarsfjellet in situ and molecular studies 2017 seasonal university of ghent, belgium verleyen unpubl. data microbial activity, soil temperature and moisture stuphallet experimental snow fence 2012 irregular university aberystwyth, uk foster et al. 2016 4 ecosystem component monitoring target spatial extent methods starting year interval responsible institution references a soil processes microbial biodiversity along environmental gradients knudsenheia experimental snow fences 2017 perennial university of ghent, belgium verleyen unpubl. data microbial c-turnover knudsenheia solvatn in situ and molecular studies 2009 annual uit the arctic university of norway tveit et al. 2013, tveit 2014, tveit et al. 2015 soil organic matter: chemical finger printing knudsenheia, ossian sarsfjellet observational 2017 annual university of rostock, germany; swiss federal research institute pushkareva et al. 2020 soil properties, mineralogy, moisture, soil organic matter, nutrients, ph knudsenheia, ossian sarsfjellet observational 2017 annual university of rostock, germany kern et al. 2019 vascular plant and lichen cover, microbial activity, soil fungal and bacterial diversity, soil temperature and moisture kongfjordneset experimental otc 2014 annual british antarctic survey, uk lim et al. 2018 5 ecosystem component monitoring target spatial extent methods starting year interval responsible institution references a invertebrates insect diversity ny-ålesund pitfall traps 2006 july (2-day interval) university of groningen, netherlands loonen unpubl. data vegetation cassiope tetragona growth ny-ålesund experimental fertilization and watering 1991, treatment stopped 1994 irregular aberdeen university, uk street et al. 2015, street et al. 2018 c. tetragona growth and reproduction ny-ålesund experimental otc 2003– 2013 irregular vrije university amsterdam, netherlands weijers et al. 2012 c. tetragona, dryas octopetala and salix polaris growth ny-ålesund experimental: fertilization 1991 irregular aberdeen university, uk baddeley et al. 1994 cryptogamic cover ny-ålesund observational 2014 annual university of rostock, technical university of kaiserslautem, germany williams et al. 2017 cryptogamic cover, plant community structure knudsenheia, ossian sarsfjellet observational 2017 annual university of rostock, germany kern et al. 2019 6 ecosystem component monitoring target spatial extent methods starting year interval responsible institution references a vegetation dryas octopetala and bistorta vivipara ny-ålesund experimental: warming (tents), fertilization treatment applied 2000–03 irregular university of manchester, uk wookey et al. 1993, wookey et al. 1994, robinson et al. 1995 grass production ny-ålesund experimental exclosures 1991 annual, weekly university of groningen, netherlands bakker & loonen 1998 microbotryum bistortarum on bistorta vivipara ny-ålesund observational 2000 annual 2000–04, irregular 2005– osaka prefecture university, japan tojo & nishitani 2005 plant community composition gåsebuknudsenheia observational 2014 annual norwegian institute for nature research bjerke et al. 2017 plant community composition ny-ålesund observational 1997 5-year interval national institute of polar research, japan uchida unpubl. data plant community composition, effect of grazing, n and c cycling thiisbukta experimental: exclosures 1998 2004 irregular annual university of antwerp, belgium; university of groningen, netherlands van der wal et al. 2001, sjögersten et al. 2012, fivez 2014 7 ecosystem component monitoring target spatial extent methods starting year interval responsible institution references a vegetation plant community composition, co2 fluxes and permafrost ny-ålesund observational 2013 irregular insubria university, italy cannone et al. 2016 plant community structure and biomass production brøggerhalvøya, sarsøyra e observational 2018 annual norwegian polar institute ravolainen unpubl. data plant phenological development ny-ålesund observational 2019 annual uit the arctic university of norway, norwegian research centre cooper & tømmervik unpubl. data snowmelt, soil physicochemical properties and vegetation patterns ny-ålesund observational 2014 irregular seoul national university, south korea park et al. 2018 vegetation community composition brøggerhalvøya, sarsøyra kaffiøyra e observational /experimental 1978 5–10 years norwegian polar institute d cooper 2006, hansen et al. 2007 8 ecosystem component monitoring target spatial extent methods starting year interval responsible institution references a herbivores barnacle goose ny-ålesund, kongsfjorden islands observational 1988 annual university of groningen, netherlands loonen et al. 1998, layton-matthews et al. 2019 svalbard rock ptarmigan abundance brøggerhalvøya observational 2019 annual norwegian polar institute fuglei & pedersen unpubl. data svalbard reindeer abundance and demography brøggerhalvøya, sarsøyra kaffiøyra c observational 1978/ 2000/ 2002 f annual norwegian polar institute hansen, pedersen et al. 2019, www.mosj.en svalbard reindeer survival and mortality; habitat use brøggerhalvøya, sarsøyra kaffiøyra c capture–mark – recapture 2014 annual norwegian polar institute pedersen & hansen unpubl. data predator arctic fox den occupancy and number of pups brøggerhalvøya/ kongsfjorden observational 1993 annual norwegian polar institute fuglei et al. 2003, www.mosj.en seabirds black-legged kittiwake abundance ossian sarsfjellet observational 1988 annual norwegian polar institute www.mosj.en brünnich’s guillemot abundance and demography ossian sarsfjellet observational 1988/ 2006 g annual norwegian polar institute descamps et al. 2021, www.mosj.en common eider abundance kongsfjorden observational 1981 annual norwegian polar institute www.mosj.en 9 ecosystem component monitoring target spatial extent methods starting year interval responsible institution references a seabirds glaucous gull abundance and demography kongsfjorden observational 2005/ 2009 h annual norwegian polar institute descamps and strøm 2021, www.mosj.en little auk demography feiringfjellet observational 2006 annual norwegian polar institute hovinen et al. 2014, www.seapop.no a see the main article for references. b amundsen–nobile climate change tower. c the sarsøyra and kaffiøyra peninsulas are located south of brøggerhalvøya in forlandsundet and are not included in fig. 1. d there were two starting years, each with different parameters. e norwegian university of science and technology and norwegian university for life sciences initiated and were formerly responsible for data collection. g abundance in 1988; demography in 2006. h abundance in 2005; demography in 2009. references see main article. http://www.seapop.no/ http://dx.doi.org/10.33265/polar.v41.6310 the queen of the arctic: louise arner boyd perspective the queen of the arctic: louise arner boyd elisabeth isaksson1 and anka ryall2 1norwegian polar institute, tromsø, norway; 2centre for women’s and gender research, uit the arctic university of norway, tromsø, norway abstract louise boyd (1887–1972) was a female pioneer in arctic research whose legacy includes the exploration of north-east greenland. in this perspective piece, we use a broad interdisciplinary approach to investigate her career as a photographer and expedition leader. when documenting glacial retreat during the 1930s, she was at the forefront of the development of glaciology as a research discipline. without family obligations and with seemingly inexhaustible financial resources, she used arctic exploration to create an independent and self-defined life for herself. keywords polar exploration; gender; glaciology; photography; greenland; norwegian polar history abbreviations ags: american geographical society mhm: marin history museum, louise arner boyd collection (san rafael, ca, usa) nbo: national library of norway (oslo) srpl: san rafael public library, louise arner boyd collection (ca, usa)   citation: polar research 2023, 42, 9075, http://dx.doi.org/10.33265/polar.v42.9075 copyright: polar research 2023. © 2023 e. isaksson & a. ryall. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 18 may 2023 correspondence elisabeth isaksson, norwegian polar institute, fram centre, po box 6606 stakkevollan, no-9296 tromsø, norway. e-mail: elisabeth.isaksson@npolar.no   introduction on 28 july 1939, a young norwegian geology student named brit hofseth met the legendary hunter–trapper gerhard antonsen, also known as “the king,” when going ashore in north-east greenland with a group of glacier researchers. antonsen had spent seven winters there alone and was on the point of having reluctantly to return to norway for medical help after he had got a knife in the eye during a violent winter storm. two days later, antonsen took the researchers in his boat from the hunting station revet to leirvåg, where they would spend a few summer weeks. after hofseth had served dinner, the party spent a pleasant evening in front of her tent. “antonsen said he was overwhelmed,” she noted in her expedition diary. “many people, hot food and a woman. he had only seen miss boyd and madame smet in 7 years” (hofseth 1939, diary entry 30 july; our translation). hofseth’s anecdote is revealing of the area of the arctic and the period this paper discusses. north-east greenland was uninhabited, but throughout the 1930s constantly visited by hunters and researchers, especially from norway and denmark. encouraging this activity was the ongoing dispute about sovereignty of the area, where both countries used research and a continued presence to assert national interests (blom 1973). as antonsen’s experience shows, visitors were, almost without exception, men. the french mathilde smet accompanied her brother, count gaston micard, on a trip to north-east greenland in the summer of 1933. in contrast, the american louise arner boyd was a regular. she went to the arctic repeatedly and she did not travel as a man’s companion but as the leader of four research expeditions. the first took place in 1931, the year before antonsen’s first overwintering, but he encountered her in the summers of 1933, 1937 and 1938. while she attracted notice as a woman in the arctic, as a female expedition leader she was a sensation. a singular figure in polar research during the interwar period, she was regularly referred to in the american press as “the queen of the arctic.” two kinds of primary sources elucidate the unique position that louise arne boyd (1887–1972) attained in international polar research during the 1930s: the books boyd published about her expeditions to greenland and the extensive archival material she left behind. the fiord region of east greenland (1935) and the coast of northeast greenland (1948) recount her activities as a photographer, topographer and expedition leader. boyd’s introductory chapters, in which she figures as an expedition leader and a pioneer in the documentation of glacial retreat, are significant contributions to the arctic expedition literature. the many photographs she took of geological formations, glaciers and iceberg-studded fjords, which lavishly illustrate the books, show an arctic landscape in constant change. the images were used for mapping purposes, but they may also be considered from a purely aesthetic perspective (rule 1998). the archival material reflects the public attention boyd received during her lifetime and shows how well-known she was on both sides of the atlantic. most of it is kept in various us archives but has not yet been fully researched, despite the publication of two biographies (anema 2013; kafarowski 2017). the ags at the university of wisconsin libraries in milwaukee has thousands of photographs and many maps; the national archives in washington, dc has 150 film reels (amidon 2010). miscellaneous material, from correspondence and private papers to scrapbooks, contracts with researchers and transcripts of radio interviews, are stored in large boxes in two archives—the srpl and the mhm—in her home state of california. there is also material about her in several norwegian archives, much of which reveals close collaboration with norwegian and nordic polar researchers. through her books and archival material, we can trace the development of louise boyd’s career as a female pioneer in arctic research and mapping. situating her in terms of the history of science, we emphasize her roles as photographer and expedition leader, especially in relation to the development of glaciology as a research discipline. finally, we highlight the continuing value of her contributions. money equals freedom education in one form or another is the basis for scientific contributions. some of the women interested in science have looked for, and sometimes found, alternatives when the official doors were difficult to open. since the 1920s, they have gained greater access to academic studies, at least in the industrialized part of the world, but many research disciplines are still characterized by gender inequality (hulbe et al. 2010). while higher education for both genders was limited by class, boyd was one of many middleand upper-class women born in the late 19th century who despite economical resources did not receive a formal academic education and therefore could have lost the opportunity to develop their full potential. that boyd would become a pioneering polar researcher was therefore not in the cards. she grew up in a wealthy family in san rafael, near san francisco, where her father, who had made a fortune during the gold rush in california in the 1870s, ran an investment company. the education she received from governesses and in private girls’ schools hardly qualified her for anything other than the role of a society wife. yet instead of marrying, she began working for the boyd investment company, eventually taking over its management and gaining valuable organizational experience that she later benefited from as an expedition leader (anema 2013; kafarowski 2017). as a young woman and only surviving child, she was responsible for the care of frail parents. when both died within a period of six months, she became the sole heir at the age of 32 to the family mansion in san rafael and a large fortune. without family obligations and with seemingly inexhaustible financial resources, boyd was able to forge an independent and self-defined life. “i realized that for my own good i must disconnect myself from the past and find and create new interests not associated in any way with the sadness that so completely absorbed many years” (4 pp. ms., mhm), she wrote in an autobiographical note about the new direction her life had taken after her parents’ death. “the most difficult mental obstacle i had to overcome was the fact that after being a definite part of other people’s lives for so many years, i was no longer needed” (4 pp. ms., mhm). she was evidently looking for a mission or sense of purpose. the same note describes an attraction to the north. on holiday in the nordic countries in 1924, boyd went on a tourist ship to spitsbergen (later svalbard) and the edge of the pack ice. “this was the part of the trip to which i had looked forward the most, because through my reading i had formed a very vivid impression of the appearance of pack ice,” (4 pp. ms., mhm) she wrote. she told the captain that she was not satisfied by a tantalizing glimpse of the ice: “i want to be in there some day, looking out; not here, looking in” (4 pp. ms., mhm). two years later, this wish was fulfilled. with the help of an english guide with extensive experience in organizing tourist expeditions to the arctic, she chartered the norwegian arctic ship hobby and went with some friends to franz josef land. on the way through the polar ice, they combined trophy hunting with photography and filming. boyd described this trip in an unpublished 57-page manuscript (boyd 1952), probably written during the 1930s and obviously intended as the introduction to a planned book about “the lighter side of her arctic explorations and expeditions” (note dated 5 august 1952, srpl). here she tried to put into words her first crucial polar experiences. ice is the leitmotif of the text. repeatedly she let herself be overwhelmed by the vast expanses of arctic ocean ice, which rendered people insignificant: “i realized it was i, not the iceberg, that was transient!” (boyd 1952: 11). she described the various ice formations in detail and wrote that she could not imagine doing “objectless sightseeing” (boyd 1952: 18). instead, she defined photography as her work: “not trained as a scientist, but trained with a camera, my eyes and theirs must do constructive and intelligent recording. therefore, my job was a two-fold one, that of the leader and photographer, and that was the simple foundation upon which my succeeding expeditions were built” (boyd 1952: 18; fig. 1). fig. 1 as a skilled landscape photographer, louise boyd contributed to arctic research and the dissemination of the beauty of arctic landscapes. this is a still from her film about the search for roald amundsen in the summer of 1928. (photo: united states national archives.) inset: boyd photographed in tromsø on 28 june, a few days before the start of the search. (photo: anders beer wille, norsk folkemuseum.) the heroic rescue attempt in 1928, she again chartered hobby for a new trophy hunting trip with friends. the planned destination was greenland, but when roald amundsen went missing she offered to make the ship and crew available without cost for the norwegian search effort. the world-renowned polar explorer had disappeared on 18 june with the french seaplane latham on its way to svalbard to assist the international rescue operation for the airship italia, which had crashed in the ice on its return from the north pole. boyd’s only prerequisites were that she and her guests would participate and the ship would sail under the american flag. she argued that hobby, designed for ice, would be able to search where other ships could not. “i had to promise to do what i could so that hobby would be used as efficiently as possible,” wrote the norwegian naval officer gunnar hovdenak, who coordinated the search operation for amundsen, “and to treat it as if there were only men on board” (hovdenak 1934: 90–91; our translation). on both this and her later expedition she was firmly opposed to special treatment of women. boyd’s offer, which covered all the costs of operating a fully equipped ship in the arctic ocean indefinitely, was gratefully accepted by the norwegian authorities. when hobby left tromsø on 3 july for svalbard, to join the international search operation and take on board two seaplanes and their pilots, boyd was no longer a private polar tourist. she completely dismissed the hunting trip from her mind, telling a norwegian newspaper: “i am willing to carry out any instructions that the norwegian government may give me” (aftenposten 1928a). ten years later, she described the demanding search in a portrait interview with the journalist alma kitchell in the series let’s talk it over on nbc radio. when asked how it was carried out, she answered that while planes were searching over large expanses of ocean, those on board the ship used binoculars to scan each foot of the ice to the extent that visibility allowed: “we all took our turn at the watch day and night, looking not only for the plane and the men, alive, but also for any telltale wood or wreckage and for bodies that might be floating. many times we stopped for what turned out to be false alarms—what often looked like a body would, on investigation, turned out to be black ice” (transcript of let’s talk it over interview 19 december 1938, srpl). after more than two months, the search formally ended when a fishing boat picked up a float from latham near a lighthouse in northern norway. for boyd personally, this experience was a turning point. although the search was fruitless, she was honoured as a hero and on 18 october appointed a knight 1st class of the royal norwegian order of saint olav, “as a visible proof of the norwegian people’s gratitude” (aftenposten 1928b). six days later, she was among the guests of honour at a large memorial meeting for amundsen arranged by the norwegian geographical society in oslo (aftenposten 1928c). here she must have become acquainted with the central norwegian polar researchers. all indications are that she was accepted by a norwegian polar elite long before she herself explicitly relinquished polar tourism for research and four years before she published her first research article in october 1932. this was solely due to her contribution to the search for amundsen. she was obviously aware of the international status it gave her to be able to associate her name with one of the greatest polar explorers (boyd 1935; willman 2016). her recognition in the us several years later was the result of arctic expeditions with american researchers. institutional affiliation and an independent network boyd was fully aware that it was her personal fortune that had enabled her to create a leading role outside established structures (hulbe et al. 2010). a footnote on the first pages of the introductions to her books, states that miss boyd had financed the expeditions. she did not attempt to hide where the money had come from. her first research article includes a footnote that explains why she wanted to call a newly discovered mountain peak in the kjerulf fjord in north-east greenland “j.f.b. mountain” after her father: “i wish to have the mountain so named in memory of my father, a pioneer in the mining industry of the west of the united states of america, through whom my arctic voyages have been made possible” (boyd 1932: 546). her willingness to use her own disposable wealth to fund research led to her collaboration with the renowned ags. from 1931 all her expeditions were officially sponsored by the ags. an independent institution whose purpose was to disseminate geographical knowledge to the general public, it accepted members on the basis of relevant experience, not necessarily academic merits (mcmanis 1996; monk 2003). boyd’s connection with the ags helped her recruit researchers for her expeditions. in return, she donated all the results to the geographic society. the books she published were part of their series of special editions but she paid for their production, according to a report entitled a brief history of miss louise a. boyd’s relation with american geographical society (archive, 6 january1960, ags archive). it was a win–win situation: she gained prestige through her affiliation with ags; the organization received valuable scientific material and fully funded expeditions and publications. as an independent researcher, boyd avoided expending time and energy building a career within the constraints of the academic world. at the same time, reading lists in the mhm’s archives, in novato, show that over time—and probably on the advice of researchers in both the nordic countries and the us—she built up extensive polar knowledge on her own. her correspondence in the archives shows that she established and maintained a valuable network of contacts. the available sources also indicate that she was welcomed as a colleague by nordic polar researchers. it was danish polar researchers who suggested naming an area of land and a glacier in greenland after her (fig. 2). in a glaciological historical context, she is an example of how women with private financial resources were able to create leading roles outside established structures (hulbe et al. 2010). fig. 2 example of a topographic map based on photographs and measurements taken by louise boyd in the field in 1933. the danish government recognized boyd’s work by naming this area miss boyd land and the glacier louise glacier. boyd is the only female polar pioneer who had land named after her in north-east greenland. (image assembled from several maps in the american geographical society library.) embracing and refining modern technology though boyd’s expeditions were comparatively “small in size both in terms of personnel and ship” (boyd 1984: 493), she was confident that investing in state-of-the-art equipment and techniques would yield results: being a firm believer that geography, certainly that of the polar regions, can best be studied by explorers and scientists equipped with the most precise and practical instruments that modern times have developed, and which would enable them to obtain the most thorough and detailed knowledge of areas not easy of access and where time plays an all important factor, i spared no effort or expense in order to equip every branch of our work along those lines. (boyd 1984: 493) her books provide detailed descriptions of the equipment and show how technology helped the researchers make the most of the short summer seasons, in spite of serious ice problems off the east coast of greenland on every expedition. boyd understood early on the importance of mapping not only the visible landscape, but also what was below sea level. before the first world war, bathymetric maps were based on rudimentary measurements from ships. however, during the 1920s, the echo sounder was developed, an instrument that made it possible to map the underwater topography along continuous profiles instead of just taking point measurements. thanks to useful contacts and a well-stocked bank account, boyd was not only able to buy the most modern equipment available for surveying the seabed, but also to contribute to its technological development. on her second expedition to north-east greenland, in 1933, she used echo sounders, but it turned out that the system had shortcomings. before the next expedition four years later, the instrument was improved using boyd’s own resources. this improved echo sounder was called the hughes veslekari model echo sounder, after the ship she chartered, and it was later put into production and used by others to sound large depths (boyd 1948: 8–9). it contributed to the discovery of the ridge in the seafloor between bjørnøya (bear island) and jan mayen, which, at the suggestion of norwegian polar researchers, was later named after boyd. her wealth also made it possible to invest in the best photographic equipment on the market. before aerial photography became commonplace, photogrammetry was used to achieve a three-dimensional representation of landscapes. it requires photographs of a given place from several perspectives. it is clear from her own writing and the expedition participants’ accounts that she devoted much energy into developing techniques to reconstruct the appearance of glaciers from images taken from different angles and she learned to adapt her instruments to local conditions. her quality-conscious approach was honed by isaiah bowman, the ags director, as revealed in their correspondence in the mhm. on the basis of the photographs produced during boyd’s 1928 expedition to greenland—which she had called “a photographic reconnaissance” (1932: 532, 1935: 2)—bowman advised her about what she ought to photograph on her next expedition and the contextual information she should provide for the images. following his guidance, armed with cameras better suited to the polar environment and taking advantage of better summer weather, boyd took photographs on her next expedition that showed such marked improvement that bowman could “hardly believe that they were taken by the same woman! you have done a first-class job” (letter from bowman to boyd 15 march 1932, mhm; letter from boyd to bowman 25 march 1932, mhm). as a result, the ags subsequently prepared (with her financing) detailed and accurate topographic maps (fig. 3). she donated all her photographs to the ags. fig. 3 this photograph, of hisingen glacier, in dickson fjord, greenland, on 6 august 1931, is one of many annotated by louise boyd to show the location of the view on a corresponding map. in this way, the photographs could be used as a basis for the construction of better maps. (photo: louise arner boyd / american geographical society library.) boyd told bowman that she had been in contact with the scott polar research institute, in cambridge, where they had asked for more of her pictures of ice forms and moraines. geologist frank debenham, who had been with polar explorer robert scott to antarctica in 1910 and was the institute’s first director, recommended that she publish collections of “ice photographs,” for example, in the form of albums with short explanatory captions. this would make the images available to students interested in glaciology. he wrote that he thought she was inclined to be “too humble minded about the value of the photographic work you have done,” and that in his opinion the pictures were extremely valuable. he therefore hoped that she would invest in such a publication (letter from debenham to boyd 12 june 1931, mhm). the encouragement from someone like debenham must have boosted her confidence and may have been an important inspiration for the publication and format of her two books, which are largely collections of arctic landscape portraits. richly illustrated with maps and photographs, the books are addressed to a general audience. almost all the images are dated, probably because they show landscapes, ice conditions and glacial formations that were constantly changing. as debenham had suggested, all have short explanatory captions. the photographs have a documentary purpose, but at the same time boyd clearly wanted to convince readers of the aesthetic value of the arctic landscapes. as she wrote in the fiord region of east greenland, “i have sought to bring east greenland before the eyes of the specialist and of all interested persons, and to do so in a form that reflects both the beauty of the region and its scientific importance” (boyd 1935: 56). the greenland expeditions boyd’s first expedition to greenland with the chartered arctic ship veslekari left ålesund, in southern norway, on 1 july 1931. glaciers in the northern hemisphere had shown signs of retreat, something that was generally ascribed to “climate improvement” (sörlin 2009: 242–243). up to date on these discussions, boyd concentrated on greenland partly because the glaciers there showed “a variety of form and of glacial action probably unsurpassed” (boyd 1932: 529). moreover, accurate topographic maps—crucial for mapping glacier fronts—were lacking for large areas of north-east greenland. veslekari was designed in 1918 as a sister ship to amundsen’s maud, with a heavy solid wooden hull and a rounded bow profile that made it possible to glide over or plough through sea ice (ellefsen & berset 1957; kjær & sefland 2005). although the ship was constructed for pelagic hunting and belonged to the shipping entrepreneur elling aarseth, in ålesund, it had been chartered several times for norwegian research expeditions in the arctic. it became a platform for boyd’s next three expeditions to north-east greenland. each time, it was rebuilt with deckhouses that served as cabins, darkrooms and “depots for her optical and photographic equipment” (ellefsen & berset 1957: 153; our translation). the swedish cartographer carl-julius anrick, who with his wife calla participated in the 1931 expedition, later called it “simply a tourist trip” (anrick 1932: 175; our translation). the probable reason is that he was the only participant who was a researcher, while the other guests on board were friends of boyd. one of them, robert menzies, was known as an amateur botanist. with a snub to the formally unqualified boyd, isaiah bowman had apologized that the researchers he was trying to recruit were engaged in “other expeditions under scientific leadership” (quoted by kafarowski 2017: 131). however, that was before he had been impressed by the quality of boyd’s photographs. on her expedition two years later, all the invited participants—with the exception of the wife of one of the researchers—were well-known scientists. the expedition in 1931 was nevertheless the beginning of boyd’s serious research career. the staff on the 1931 expedition included 23-year-old erik bratseth, from ålesund, who had been hired “exclusively as miss boyd’s camera carrier” (anrick 1932: 175; our translation). bratseth’s diary (bratseth 1931) from the trip gives a vivid picture of boyd as expedition leader and photographer and the physical demands of photographing under extreme conditions. on the voyage to greenland, veslekari stopped at the island of jan mayen. there, on 10 july, bratseth noted that the fog cleared so much that “miss boyd could try her large camera for colour photography. it is a very sizable device with two large handles to hold it up against the chest. enormous lens and wide film strip with 25 consecutive images” (bratseth 1931, diary entry 10 july; our translation). the heavy and cumbrous camera equipment, including glass plates and developing fluids, was not easy to bring out into the terrain, and it was bratseth’s task to assist on such trips. during the expedition, it became clear that boyd had identified an area of north-east greenland that had not been explored and where she could make a valuable contribution with her photographs. at ymer ø, at the entrance to kaiser franz joseph fjord, bratseth wrote that the expedition participants understood that “a correction of the map was obviously needed here” because the distance between kjerulf fjord and dickson fjord was less than what was marked on the map (bratseth 1931, diary entry 10 august; our translation). bratseth speculated that “miss boyd was probably a little disappointed that she had not discovered any new floating area between the two fjords, but it was probably a consolation to her to discover that the map was wrong” (bratseth 1931, diary entry 10 august; our translation). on this expedition boyd laid the foundation for the topographical work that required photographic precision, refining the photographic and topographical mapping technology that she had learned to use. on all subsequent expeditions she brought with her a professional topographer. “when i was photographing for the purpose of recording typical topographic forms, glaciers, ice, fine scenery, animal life, and forms, no day was ever long enough for the fascinating work,” she wrote many years later (boyd 1948: 87): it was quite a different matter, however, to spend hour after hour photographing for mapping purposes. there the surveyor and i worked together as a unit, he with his plane table and i with my cameras, recording the material from which detailed maps could be worked up by him after the return of the expedition. this is to be recommended as an ideal method for mapping when time is short. (boyd 1948: 87) even anrick admitted in his report that the challenges of the ice in the eastern part of greenland made the trip in 1931 worthy of being called an expedition. he could also have emphasized that they were the first ever to cross the ice at the entrance to icefjord on the north-east coast and that they discovered several other places where existing maps were incorrect. altogether, the expedition visited all the fjords between kaiser franz joseph fjord and king oscar fjord. whenever possible they went ashore, and boyd photographed the same landscapes from different clearly defined vantage points, which often required a good deal of climbing for her and her young camera carrier (boyd 1948, 1984). boyd also gained a general understanding of the weather and ice conditions in the ocean surrounding greenland, knowledge that was important in planning future voyages. the expedition in 1931 was the last for which boyd left the logistics to others. on her next expeditions to north-east greenland, she had full command. in addition to being responsible for funding, she took charge of all the practicalities: chartering research vessels, scheduling, selection of participants, ordering provisions and equipment—everything that did not concern the collection of research data. in 1933, with the assistance of bowman at ags, she put together a group of researchers with competence in what she considered important. in the small group of researchers who were selected to participate, two were devoted to cartographic work on land and two were geologists. on her last two expeditions, in 1937 and 1938, which were planned as a unit, she also brought with her a hydrographer with expertise in handling the echo sounder. it was clear that she had gradually prioritized innovation over more traditional research methods: “greater emphasis was to be put on the hydrographic work than had been the case in any of my previous expeditions,” she wrote in the coast of northeast greenland, “and a hydrographer, who was to be in charge of the sounding program, current studies, and tide-gauge recording, was therefore added to the staff” (boyd 1948: 4). echo-sounder profiles were made of several fjords, and fairly continuous sound lines were also made between norway and greenland. the collection of this type of data was an important contribution to the ongoing debate on landscape development and the effect of different types of erosion. clearly, the debate on continental drift—which would not be settled for several decades—also benefited from better knowledge of what was hidden beneath the sea surface. the expedition leader in louise boyd’s time, polar expeditions often included several types of researchers because there were many aspects to study: botany, glacier fronts, geology, geomorphology—in addition to the necessity of mapping large areas. then as now, the organization of successful expeditions depended on knowledge of logistics and meteorology and, not least, leadership skills. boyd was not only the expedition leader, she also participated in the research as a photographer and therefore had to master various roles on her expeditions. boyd reflected on her roles in a portrait written in advance of her 1938 expedition by the well-known journalist russell owen for the new york times magazine. initially she did not want to talk about herself, telling owen that “i did not know when i started out if i was suited for leadership, particularly with a group of men; and second whether i could contribute anything of value” (owen 1938: 6). she was nevertheless convinced that she has contributed new knowledge and believed that she has succeeded as a leader: “as for the men, most of them go back with me each voyage. we get along fine” (owen 1938: 6). even though she claimed that her leadership of expeditions, in which all the other participants were men, was unproblematic, the available sources indicate that she downplayed the challenges of asserting herself as a woman in the male-dominated world of polar science. when asked in a radio interview in 1939 what particular obstacles she had had to overcome in her polar career, she stated that “being a woman” and the lack of formal scientific qualifications had been problems: “when i first went to the arctic, people definitely seemed to feel, and openly told me so, the arctic was a place only for men—that for me to go where i did was an eccentricity and hobby and not to be taken seriously,” she said (transcript of it can be done radio interview, 3 may 1939, srpl). neither mapping nor photography required a university degree, but her lacking academic education made her feel less valued, even though “in many cases, it has happened that i have had more actual experience and field work than those so-rated scientists whose knowledge was limited only to books and who did not have the practical application of it” (transcript of it can be done radio interview, 3 may 1939, srpl). however, there are many indications that boyd usually managed to command respect as the expedition leader. before researchers could join her expeditions, they had to sign contracts that gave her full control over the dissemination of their results. it is interesting to study the contract she created for professor j. harlen bretz of the university of chicago, who was a physiographer on the 1933 expedition. it shows both a confidence in her own capacity as leader and a clear understanding of the academic process (contract signed 22 march 1933, mhm; letter from bretz to boyd 28 march 1933, mhm). in this context boyd must have benefited from her knowledge and experience of the business world. apparently, she got along well with the crews on the norwegian ships she chartered. in the preface to the coast of northeast greenland, she praised both the captain and first mate of veslekari: “greater loyalty and greater efforts than theirs on our behalf could not have been possible,” she wrote (boyd 1948: x). “their long hours of work, their tenacity in getting the ship through difficult ice conditions, their interest in making it possible for us to reach our objectives, often under the most trying circumstances, deserve the highest admiration and respect” (boyd 1948: x). since the same crew, with some exceptions, participated in all her research expeditions, the respect and admiration were probably mutual. the fact that boyd never suffered from seasickness may have contributed to her gaining the crews’ respect. according to the authors of a book about her expedition vessel, veslekari, the captain was impressed with her seamanship. she was an expert in knotting, splicing and tackling, she even demonstrated wire splicing with brilliance. if the weather was ever so rough and the ship ever so rolling, she came striding out of her cabin on the foredeck, found her sea legs and entered the wheelhouse on her daily cross-examination about everything between heaven and earth. (ellefsen & berset 1957: 159; our translation) her camera carrier, bratseth, recounted something similar in a diary note about a violent storm on the trip to greenland: “miss boyd enjoyed herself immensely,—heavy sea, accompanied by the howls of female expedition members and the crash of cups falling to the floor and breaking en masse” (bratseth 1931, diary entry 14 july; our translation). as the leader of polar expeditions, boyd—like others in the same situation—faced many challenges in terms of competence, gender and social class. the ability to create a well-functioning working environment on an expedition is crucial to the success of the research itself. an experienced society hostess, boyd transferred her sophisticated habits to an expedition setting. on her expeditions, no expense was spared, not even of first-class provisions (kafarowski 2017: 165–167). professor bretz was critical of the lavish catering on veslekari: “in the middle of this riot of nature untamed, we sup in royal fashion, a highball for aperitif, port with the last of the meal,” he wrote in his diary (quoted by kafarowski 2017: 178). boyd had undermined the manly tradition of simple living in the field and bretz clearly disliked both the luxury and the female influence. the plant ecologist henry j. oosting, who participated on boyd’s 1937 expedition, likewise complained in his diary of the “la femme atmosphere” on the vessel (quoted by kafarowski 2017: 205). in his diary, bretz did not hide his contempt for boyd as leader. he complained about “her awful irrelevance, her terrible clack, her frightful sentences, her selfishness, her incompetence to lead a scientific expedition” (quoted by kafarowski 2017: 179). there is no reason to think that boyd was actually an incompetent expedition leader: it is her manner and character that are attacked here, by a prominent male researcher whose private writings reveal his misogynistic attitudes. how representative he was is hard to say. he may have been an exception, or other scientists on her expeditions may have shared the same views without expressing them either publicly or privately. like other women in traditionally masculine roles, boyd found herself between the devil and the deep blue sea. as a female leader, she could be undermined by men like bretz. she also felt compelled to explain that leading polar expeditions had not made her masculine: “i like the pleasant things most women enjoy, even if i do wear breeches and boots on an expedition, even sleep in them at times,” she told owen in 1938. “i have no use for masculine women. at sea i do not bother with my hands, except to keep them from being frozen, but i powder my nose before going on deck, no matter how rough the sea is. there is no reason why women can’t rough it and still remain feminine” (owen 1938: 6). yet no matter what people around her thought of her as a woman and leader, she was in charge. she not only paid for everything, but also organized and led the expeditions and controlled the dissemination of the results. boyd’s glaciological legacy people’s interest in looking beyond the beauty of ice masses and seeking to understand how they work grew strongly during the 19th century, partly because in inhabited areas one could see with one’s own eyes evidence of how past glaciers had advanced (clarke 1987). in scientific circles it became generally understood during this time that the glaciers of earlier epochs were considerably larger. likewise, it was accepted that glacial erratics (rocks left behind by retreated glaciers) and glacial striae (stripes scraped into rock by moving glaciers) were evidence that ice-free areas had previously been covered by ice, and that ice movements had had a great impact on the landscape development (boulton 1987). moreover, it became increasingly clear that glaciers had been greatly influenced by the modern climate. this contributed to systematic studies of glaciers to understand how they functioned, which led to the emergence of glaciology as a separate research discipline. given very few opportunities to participate in fieldwork, many of the female pioneers of glaciology excelled in other ways, carrying out laboratory work and book projects, for example (hulbe et al. 2010). some women in the profession chose to live without domestic obligations, which gave them more freedom to take advantage of the chances that presented themselves, and boyd can be considered one of them. her glaciological legacy lies mainly in her photographs of glaciers and landscape forms from her four expeditions to greenland. with the rapid global warming that is now taking place, glacial ice is shrinking at breath-taking speed and contributing to global sea level rise. because warming has increased three times as fast in the arctic as in nearby geographical areas, greenland’s ice cover has received enormous attention in recent decades. after all, the ice in greenland corresponds to 7 m of sea level. glaciers that calve into the ocean are sensitive not only to atmospheric warming but also to ocean currents and water temperatures. since it has been shown that the greenland ice sheet does not behave as a homogeneous mass, scientists today seek to understand individual glaciers and how each behaves. historical archives, including boyd’s photographs and topographic maps, have proven to be a valuable resource. scanning the photographs and applying modern photogrammetric processing techniques have yielded accurate topographic data that may be compared with recent images taken from aircraft, drones or satellites. ninety years after boyd photographed greenland’s glaciers, danish glaciologist anders björk photographed several of the same glaciers again, allowing him to document changes in their front positions and calculate volume changes (bjørk et al. 2018; fig. 4). fig. 4 boyd’s photograph of morainless glacier is an example of the high technical quality of her images, which make it possible to study the different structures in the ice. (photo: louise arner boyd / american geographical society library.) “why feminist glaciology?” ask carey et al. (2016), in a controversial article about women and gender in glaciological research. in addition to calling for a focus on women’s contributions to the development of the field, they also ask to what extent the discipline itself is gendered. they claim that glaciology—especially when it is associated with rock climbing and polar expeditions—is characterized by a masculine discourse that privileges physical achievement, heroism and conquest (carey et al. 2016: 5). it is striking that these qualities are missing in boyd’s descriptions of her own expeditions. she does not deny that the weather and nature conditions were often challenging, but instead emphasizes what can be called her dialogue with the arctic. as her books show, it was within this dialogue that her photographs were created. carey et al. (2016) conclude that as a research discipline glaciology must be seen in the context of the global environmental challenges humanity is facing, and that it is therefore important to take a broad humanistic and social-science perspective on studies of ice. they claim that “alternative representations,” such as art and literature, can help to articulate new versions of the relationship between humans and glaciers (carey et al. 2016: 14). thus, ice will not only be the subject of measurements, mapping and quantifying investigations, but also of an emotional, aesthetic approach (carey et al. 2016). in this sense, boyd’s photographs are exemplary. on the one hand, they have the status of scientific data; on the other hand, they open our eyes to the beauty of arctic landscapes. a pioneer in a book about the ship veslekari, the authors characterized boyd as “a filthy rich female, tanned like an arctic skipper,” but they also recognized her as “one of the world’s few women polar scientists” (ellefsen & berset 1957: 150–151; our translation), suggesting that they understood that she had uniquely managed to straddle the expectations of the society into which she was born and an unparalleled polar career. one may surmise that she was more easily accepted—and her accomplishments more readily recognized—in scandinavia because she was an exotic element there. the louise boyd collection at the ags archive in milwaukee contains several thousand photographs of icebergs, glaciers, snow, sea ice and landscape formations. today’s readily available photographic technology has made it easy to forget the physical challenges behind the old pictures in various archives. photographs and maps are important visual cultural monuments, and boyd’s detailed historical documentation is an invaluable treasure for posterity precisely because the landscape in the polar regions is changing so rapidly. her images are being used in today’s glaciological research and their value will not diminish in the future. during the 1930s, boyd was able to participate in modern polar research because she had personal economic resources. her independent economic situation opened many doors, but she would not have come far without intelligence, ingenuity, ambition and a capacity for hard work. lacking academic qualifications, she nevertheless became accepted in a male-dominated environment because she took chances, established a contact network and made herself competent in the relevant fields. as an expedition leader and photographer, she pointed forward. she participated in the emergence of glaciology as a modern research discipline. most importantly, her many photographs of disappearing polar landscapes survive her. writing in 1950, boyd called the small expeditions she organized in the 1930s insignificant—“a dot among the others and of very questionable good” (boyd 1984: 499)—compared to the enormous research activity in the arctic after world war ii. still, she expressed pride in what she had accomplished: “we pioneered where others now carry on” (boyd 1984: 499). references aftenposten 1928a. miss boyd om sin ekspedisjon. (miss boyd on her expedition.) aftenposten, 2 july. aftenposten 1928b. kongen taler for miss boyd og marine-flyverne. (the king makes a speech to miss boyd and the naval pilots.) aftenposten, 18 october. aftenposten 1928c. et stemningsfullt minnemøte. (a moving memorial meeting.) aftenposten 25 october. amidon a. 2010. women in the polar archives: the films and stories of marie peary stafford and louise boyd. prologue 42, 38–45. anema d. 2013. taming the arctic: the 20th century renown arctic explorer louise arner boyd. parker, co: national writers press. anrick c.-j. 1932. en sommarresa till østgrönland. (a summer trip to east greenland.) ymer 52, 175–212. bjørk a.a., aagaard s., lütt a., khan s.a., box j.e., kjeldsen k.k., larsen n.k., korsgaard n.j., cappelen j., colgan w.t., machguth h., andresen c.s., peings y. & kjær k.h. 2018. change in greenland’s peripheral glaciers linked to the north atlantic oscillation. nature climate change 8, 48–52, doi: 10.1038/s41558-017-0029-1. blom i. 1973. kampen om eirik raudes land. pressgruppepolitikk i grønlandsspørsmålet 1921–1931. (the fight for erik the red’s land and pressure group politics in the greenland issue, 1921–1931.) oslo: gyldendal norsk forlag. boulton g.s. 1987. progress in glacial geology during the last fifty years. journal of glaciology 33(s1), 25–32, doi: 10.3189/s0022143000215797. boyd l.a. 1932. fiords of east greenland: a photographic reconnaissance throughout the franz josef and king oscar fiords. the geographical review 22(4), 529–561. boyd l.a. 1935. the fiord region of east greenland. new york: american geographical society. boyd l.a. 1948. the coast of northeast greenland with hydrographic studies in the greenland sea. new york: american geographical society. boyd l.a. 1952. 57-page manuscript. ca: san rafael public library, louise arner boyd collection. boyd l.a. 1984 (1950). the louise a. boyd seven arctic expeditions. journal of the american society of photogrammetry 1(4), 493–499. bratseth e. 1931. dagbok fra grønlandsekspedisjonene med louise arner boyd 1931. (diary from the greenland expeditions with louise arner boyd 1931.) accessed on the internet at https://sites.google.com/site/kjerstishjemmeside/ on 9 march 2023 carey m., jackson m., antonello a. & rushing j. 2016. glaciers, gender, and science: a feminist glaciology framework for global environmental change research. progress in human geography 40, 770–779, doi: 10.1177/0309132515623368. clarke g.k.c. 1987. a short history of scientific investigations on glaciers. journal of glaciology 33(s1), 4–24, doi: 10.3189/s0022143000215785. ellefsen e. & berset o. 1957. “veslekari”. en fortelling om is og menn. (“veslekari.” a story of ice and men.) bergen: j.w. eides forlag. hofseth b. 1939. dagbok for claveringøya sommeren 1939. ubehandlet 307. (diary for clavering ø [clavering island], summer 1939.) oslo: national library of norway. hovdenak g. 1934. roald amundsens siste ferd. (roald amundsen’s last journey.) oslo: gyldendal norsk forlag. hulbe c.l., wang w. & ommanney s. 2010. women in glaciology, a historical perspective. journal of glaciology 56, 944–964, doi: 10.3189/002214311796406202. kafarowski j. 2017. the polar adventures of a rich american dame: a life of louise arner boyd. toronto: dundurn. kjær k.g. & sefland m. 2005. the arctic ship veslekari. polar record 41, 57–65, doi: 10.1017/s0032247404003997. mcmanis d.r. 1996. leading ladies at the ags. the geographical review 86, 270–277, doi: 10.2307/215960. monk j. 2003. women’s worlds at the american geographical society. the geographical review 93, 237–257, doi: 10.1111/j.1931-0846.2003.tb00031.x. owen r. 1938. a woman makes her mark in a man’s world. new york times magazine, 1 may, pp. 6, 20, 23. rule a. 1998. ansel adams and louise arner boyd: a camera tells a story. history of photography 23, 155–160, doi: 10.1080/03087298.1998.10443871. sörlin s. 2009. narratives and counter-narratives of climate change: north atlantic glaciology and meteorology, c. 1930–1955. journal of historical geography 35, 237–255, doi: 10.1016/j.jhg.2008.09.003. willman m. 2016. seeing with a new lens: louise arner boyd’s polar expeditions. in m.a. cabañas et al. (eds.): politics, identity, and mobility in travel writing. pp. 183–193. new york: routledge. distribution and habitat characteristics of pinnipeds and polar bears in the svalbard archipelago, 2005–2018 research article distribution and habitat characteristics of pinnipeds and polar bears in the svalbard archipelago, 2005–2018 olof bengtsson, charmain d. hamilton, christian lydersen, magnus andersen & kit m. kovacs norwegian polar institute, fram centre, tromsø, norway abstract this study presents comprehensive mapping of the current distribution of pinnipeds and polar bears (ursus maritimus) around svalbard based on a regional marine mammal sightings programme and explores time-trends (2005–2018). walruses (odobenus rosmarus) were observed with high frequency and in high numbers around previously identified haul-out sites. at-sea walruses were seen close to the coast in shallow waters. ringed seals (pusa hispida) were observed in coastal areas throughout svalbard, often in association with tidewater glacier fronts. there was no increase in the mean latitude for ringed seal observations, but there was an increased frequency of observations at around 82°n, which reflects their following a northward shift in the ice edge during summer foraging trips. bearded seals (erignathus barbatus) were observed frequently in north-western spitsbergen and shared many habitat features with ringed seals. there was a slight increase in the mean latitude of bearded seal observations and a decreased frequency of observation in the southern parts of the archipelago, suggesting that this species might be shifting its distribution. harbour seal (phoca vitulina) observations within fjords have increased, likely as a consequence of increased inflow of atlantic water into west coast fjords. harp seals (pagophilus groenlandicus) were observed with high frequency north of svalbard. hooded seals (cystophora cristata) were observed only rarely. polar bears were reported most frequently, undoubtedly as a result of an effort bias favouring this species. in spite of biases, citizen-based observations are useful for assessing broad distributional patterns of marine mammals through time. keywords: arctic, climate change, erignathus barbatus, pusa hispida, range shifts, ursus maritimus abbreviations imr: institute of marine research, norway kde: kernel density estimation mmsdb: marine mammals sightings database modis: moderate resolution imaging spectroradiometer (satellite instrument) npi: norwegian polar institute sst: sea-surface temperature citation: polar research 2021, 40, 5326, http://dx.doi.org/10.33265/polar.v40.5326 copyright: polar research 2021. © 2021 o. bengtsson et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 04 february 2021 competing interests and funding: the authors report no conflict of interests. the mmsdb is a project run by the npi. the analyses herein were undertaken as part of the eu grant enabling the adaptive co-management of social–ecological fjord systems in the arctic (face-it) project (no. 860154). correspondence to: kit m. kovacs, norwegian polar institute, fram centre, po box 6606 langnes, no-9296 tromsø, norway. e-mail: kit.kovacs@npolar.no to access the supplementary material, please visit the article landing page   introduction the arctic is one of the regions of the globe where the impacts of climate change are being seen most indisputably (ipcc 2014; pörtner et al. 2019). global warming has led to increased air and water temperatures, reduction of sea ice and melting of glaciers, among other physical changes to the environment (maslanik et al. 2007; spielhagen et al. 2011; nuth et al. 2013; serreze & stroeve 2015). these changes have been especially pronounced in the barents sea area, which is directly influenced by the inflow of warm (mixed) atlantic water from the south (tverberg et al. 2014; laidre et al. 2015; lind et al. 2018). since the beginning of the 2000s, the west spitsbergen current, which runs along the continental shelf break west of the high-arctic svalbard archipelago, has warmed markedly (spielhagen et al. 2011). as a result, the marine ecosystem around svalbard is being affected quite dramatically, giving rise to concern for arctic species in the region (kovacs et al. 2011; fossheim et al. 2015; descamps et al. 2017). there is therefore a need to study and monitor species distributions in order to document climate change impacts and to provide useful data for management bodies involved in spatial planning and protective measures (e.g., laidre et al. 2015). all of the north atlantic arctic pinnipeds are found in and around svalbard, including year-round resident ringed seals (pusa hispida), bearded seals (erignathus barbatus) and walruses (odobenus rosmarus), as well as seasonally-resident harp seals (pagophilus groenlandicus) and hooded seals (cystophora cristata) (smith & lydersen 1991; gjertz et al. 2000a, b; kovacs et al. 2014). additionally, there is a resident population of harbour seals (phoca vitulina), which is the northernmost population of this wide-ranging, but largely north-temperate, species in the world (merkel et al. 2013; blanchet et al. 2014; hamilton et al. 2014). polar bears (ursus maritimus) also range throughout the svalbard archipelago (mauritzen et al. 2002; aars et al. 2017; lone et al. 2018). all of these marine mammals are high-trophic predators. the pinnipeds feed on a wide variety of fish and invertebrate species (lydersen et al. 1989; lydersen et al. 1991; andersen et al. 2004; skoglund et al. 2010). pinnipeds themselves are prey for polar bears as well as greenland sharks (somniosus microcephalus) and arctic foxes (vulpes lagopus) (lydersen & gjertz 1986; derocher et al. 2002; leclerc et al. 2012). ringed seals have a close association with ice and occupy fjord habitats as well as offshore drift-ice areas (gjertz et al. 2000a; wathne et al. 2000; hamilton, lydersen et al. 2015; hamilton et al. 2016). bearded seals are also found within fjords, generally occupying shallow areas (hamilton et al. 2018, 2019). walruses concentrate in shallow areas in summer periods when they haul out on land but spend time offshore in drift-ice during winter (gjertz, griffiths et al. 2001; hamilton, kovacs et al. 2015). the harbour seal population in svalbard is concentrated around prins karls forland, west of spitsbergen (gjertz, lydersen et al. 2001; blanchet et al. 2014; hamilton et al. 2014). this species avoids heavy concentrations of sea ice, uses land as a haul-out platform and feeds in relatively shallow coastal waters, preferring the shelf edge west of spitsbergen for foraging (blanchet et al. 2014). harp seals and hooded seals in the barents sea spend most of their time in drifting pack-ice areas and migrate seasonally to breed in the greenland sea or in the white sea (haug et al. 1994; folkow & blix 1999; folkow et al. 2004). polar bears are also highly dependent on sea ice as a hunting ground and seem to prefer first-year ice, over the continental shelf or in coastal areas (larsen 1986; durner et al. 2009; lone et al. 2018). sea ice is particularly important to female bears as a transport corridor for travelling from the drifting pack ice to the denning areas on land, and for moving between areas with small cubs (stirling & derocher 2012). the sea-ice dependence of all of these arctic marine mammals makes them acutely susceptible to the negative impacts of climate change on their primary habitat. the situation for harbour seal is in marked contrast because the svalbard archipelago is likely to become a more suitable habitat for this species (blanchet et al. 2014). all of the pinnipeds that reside in, or frequent svalbard waters, as well as the polar bear, have been the subjects of tracking studies, which provide considerable insight into their distributional ecology and habitat needs (blanchet et al. 2014; hamilton, lydersen et al. 2015; lowther et al. 2015; hamilton et al. 2016; hamilton et al. 2018, 2019; lone et al. 2018). however, the specific sites where animals are captured does create geographical biases in area use and environmental conditions within the archipelago are changing very rapidly. using citizen science in the form of extensive observations made throughout most of the svalbard archipelago over a period of close to two decades, provides a complementary large-scale data set for mapping species distributions and changes in them over time. it is also a good way to engage the public and to raise awareness and interest in climate change impacts on nature (silvertown 2009; vann-sander et al. 2016). storrie et al. (2018) used the npi’s mmsdb to analyse the distribution and habitat characteristics of cetaceans around svalbard during the period 2002–2014. the study contributed the first comprehensive baseline description of cetacean assemblages in svalbard and documented signs of northward range expansions for many species (storrie et al. 2018). the purpose of the current study was to conduct similar analyses for seals and polar bears in order to (1) increase knowledge of the distributions of pinnipeds and polar bears around svalbard, (2) to analyse habitat characteristics for the various species to increase predictive capacity for assessment of climate change impacts and (3) detect potential distributional shifts over time—using the mmsdb records for pinnipeds and bears. materials and methods observations of marine mammals in svalbard have been collected since 2002; they are stored in the mmsdb (https://data.npolar.no/sighting/), managed by the npi. observations of marine mammal species are recorded with date and coordinates, along with some information about species, number of individuals in a group, maturity status or other things of note regarding behaviour, body condition etc., as well as the name of the reporting vessel and a contact person. marine cruise expedition operators, the norwegian coast guard, personnel on research expeditions (e.g., npi and imr), local residents and the governor of svalbard’s field inspectors all report sightings to the mmsdb. the reporting area is svalbard fjords and surrounding waters, 74–84°n and 0–35°e (fig. 1). for this study, the period 2005–2018 was selected because these years offered sufficient sample sizes; in the early years of mmsdb (2002–04), records were limited. figure 1 map of the study region, showing names of places mentioned in the text. arrows show ocean currents present around svalbard; wsc: west spitsbergen current; esc: east spitsbergen current; scc: south cape current. red arrows represent currents of atlantic water and blue arrows represent arctic water. environmental variables in order to characterise habitats used by the study species, environmental variables were extracted from grid files for each observation, based on the coordinates of the observations, using the raster package in r version 3.5.2 (r development core team 2018). monthly daytime sst at 11 μm wavelength, with a 4-km resolution, was acquired from the modis system (nasa 2014). ssts were assigned to each observation using a 12-km radius buffer (calculating the mean temperature even when observations had coordinates on land, that is, animals hauled out). the buffer radius was gradually increased to 130 km for observations where the original buffer was too small to assign a value, as in the case of animals observed deep in pack ice. in such cases, an sst of 0°c was assigned to reflect the sst of water in proximity to sea ice. sea-ice charts, produced by the ice service of the norwegian meteorological institute (http://osisaf.met.no/p/ice/index.html) were used to acquire data on daily sea ice coverage. these charts categorise sea-ice coverage in the following categories: 0%, 0–10%, 10–40%, 40–70%, 70–90%, 90–100% and 100%. bathymetry values were acquired from the international bathymetric chart of the arctic ocean version 3.0 (jakobsson et al. 2012). because of the resolution of this chart (500 m × 500 m), depth was divided into categories of < 5 m, 5–25 m, 25–50 m, 50–100 m, 100–200 m and > 200 m. distance from the coast and distance from tidewater glacier fronts was calculated using the ‘rgeos’ package in r together with polygon shape-files of the svalbard archipelago and tidewater glacier fronts (kohler et al. 2018). data analysis kdes for each species were calculated with the ‘ks’ package in r, using a normal scale bandwidth selector and a grid size of 1 km, displayed with 10 quantiles (silverman 1986; chacón & duong 2018). following storrie et al. (2018), temporal changes of observation frequencies were visualised by taking kdes for the first half of the study period (2005–2011) and subtracting them from kdes calculated for the most recent half of the study period (2012–18). a land polygon for the svalbard archipelago was plotted on top of the kernels for visual representation of kdes, since the ‘kde’ function in the ‘ks’ package in r does not discriminate between land and sea. this results in masking of observations inland, but given the coastal distribution of the study species and the coastal nature of the observations reported to the mmsdb, this is a minor concern; only bears walk across land/glaciers and the coastal observation platforms would rarely see these animals if they were more than 1 km inland in any case. to explore potential trends with regard to latitudinal changes over time, linear regressions of yearly mean latitude were calculated for each species. level of significance was set at α = 0.05. results a total of 127 573 individual animals, derived from 6985 observations of pinnipeds and 4002 observations of polar bears (involving 7248 individual polar bears) were recorded in the mmsdb during the study period (table 1). most of the observations (9333; 85%) were made during the summer months (june–august), while 14% were during the months when there was a mix of light and dark. ninety-one (0.8%) observations were reported during the polar night (november–february): 52 (57%) were of polar bears; 16 (18%) were of walruses; and 10 (11%) were of bearded seals.   table 1 number of observations and number of individuals, median group size and the largest recorded group size for pinniped species and polar bears in the mmsdb for the years 2005–2018; early (2005–2011) and late (2012–18) records are identified in parentheses. species number of observations (early period / late period) total number of individuals median group size largest groupa size bearded seal 1503 (536 / 967) 3969 1 58 harbour seal 513 (97 / 416) 4600 2 151 harp seal 848 (342 / 506) 32 783 6 10 000 hooded seal 45 (18 / 27) 52 1 3 ringed seal 764 (312 / 452) 5569 1 320 walrus 2848 (939 / 1909) 75 416 6 1000 unidentified pinniped 464 (262 / 202) 5184 1 1000 polar bear 4002 (1433 / 2569) 7248 1 20 a‘group’ includes animals observed in the same area and does not necessarily refer to a social group. the polar bear was the most frequently reported species, followed by the walrus (table 1; fig. 2a). the walrus was the species with the greatest number of individuals (75 416), followed by the harp seal (32 783; table 1; fig. 2b). most observations were of single animals. however, both harp seals and walruses had median group sizes of six and were on a few occasions observed in larger groups of 1000 animals or more (table 1). figure 2 (a) yearly percentage of observations for different species of pinnipeds and the polar bear recorded in the mmsdb during 2005–2018. (b) yearly percentage of animals for different species of pinnipeds and the polar bear recorded in the mmsdb during 2005–2018. sample sizes for each year are given over the corresponding bars. resident pinnipeds walruses walrus observations occurred most frequently around the north-west corner of spitsbergen, in forlandsundet and in the area between torellneset and wahlbergøya on nordaustlandet, in the north-east of the archipelago (fig. 3a). in terms of the number of animals, most individuals were observed around moffen, storøya and torellneset (fig. 3b). walrus observations were recorded in areas with relatively shallow water; 57% of the observations were from areas with a depth of less than 5 m (this includes animals on shore) and only 8% of the observations were from areas with a depth > 100 m (fig. 4a). walruses were generally observed in areas with little or no sea ice (53%); 9% of the observations of this species were from areas with ≥ 40% ice cover (fig. 4b). walruses were generally observed close to the coast (median = 0.3 km; fig. 4c), but not close to tidewater glacier fronts (median = 17 km; fig. 4d). the median sst in the areas in which they were observed was 2.9°c (fig. 4e). figure 3 kde plots showing observation frequencies of walruses around svalbard during 2005–2018, based on (a) number of observations and (b) number of animals observed. black circles mark locations of observations. figure 4 environmental variables for observations of seven different species of marine mammals that were recorded in the mmsdb during 2005–2018. (a) depth, (b) ice cover, (c) distance to coastline, (d) distance to tidewater glacier front and (e) sst. boxplots show values between the 25th and the 75th percentile within boxes that are divided by the median. vertical lines outside the boxes extend to the maximum and the minimum values up to 1.5 times higher or lower than the upper and lower quartile. dots represent outliers, more than 1.5 times higher or lower than the upper and lower quartile. ringed seals ringed seals were observed most frequently in north-western spitsbergen but were seen in coastal areas throughout the archipelago and in areas with drifting ice north of spitsbergen (fig. 5a). in terms of number of animals, frequencies were high in isfjorden, hornsund and wahlenbergfjorden (fig. 5b). ringed seals were generally observed close to land in relatively shallow areas. the median distance from the coastline was 1.2 km (fig. 4c) and 45% of the observations were from areas with a depth of < 5 m. an additional 31% of the observations of ringed seals were from areas with a depth between 5 and 100 m (fig. 4a). ringed seals were often seen in ice-filled waters, 17% of the observations were from areas with sea-ice concentration of ≥ 70% (fig. 4b). in this high ice concentration category, 61% of the sightings involved seals hauled out on ice, 20% were in the water and the last 19% lacked specific information regarding the activity of the seals. ringed seals were often observed close to tidewater glacier fronts (median = 7.3 km; fig. 4d) and in areas with moderate sst (2.8°c; fig. 4e). figure 5 kde plots showing observation frequencies of ringed seals and bearded seals around svalbard during 2005–2018, based on (a) number of ringed seal observations and (b) number of ringed seals observed; (c) number of bearded seal observations and (d) number of bearded seals observed. black circles mark locations of observations. bearded seals bearded seals were most commonly observed in the north-west corner of svalbard (fig. 5c, d). they were usually close to the coast (median = 1.0 km; fig. 4c) in shallow areas; 46% of the bearded seal observations were from areas with a depth of ≤ 5 m and 34% of the observations for this species were in areas with a depth between 5 and 100 m (fig. 4a). similar to ringed seals, the bearded seal was commonly observed in areas with sea-ice concentrations ≥ 70% (13%; fig. 4b) and close to tidewater glacier fronts (median distance = 7.1 km; fig. 4d) and the median sst for this species was 3.1°c (fig. 4e). harbour seals harbour seals were almost exclusively observed on the west coast of spitsbergen, with the exception of one observation of a single animal in wahlenbergfjorden and two observations of single animals on edgeøya (fig. 6a). the highest frequency of observations and the greatest numbers were seen in smeerenburgfjorden (fig. 6). harbour seals were observed close to the coast (median = 0.2 km; fig. 4c) and also modestly close to tidewater glacier fronts (median = 6.0 km; fig. 4d). they were the pinniped with the highest percentage of observations in shallow areas (including hauled out animals—80% from 5 m or less; fig. 4a) and the species with the highest percentage of observations in ice-free waters (64%). only 1% of the observations were from areas with ≥ 40% ice cover (fig. 4b). harbour seals were also the species that occurred in areas with the highest median sst (4.9°c; fig. 4e). figure 6 kde plots showing observation frequencies of harbour seals around svalbard during 2005–2018, based on (a) number of observations and (b) number of animals observed. black circles mark locations of observations. polar bears polar bears were seen most commonly in north-western spitsbergen, around raudfjorden, both in terms of number of observations and number of animals observed (fig. 7). they were observed at a median distance of 0.4 km from the coast and were not tightly associated with tidewater glacier fronts (median distance 14 km; fig. 4c, d). polar bears were often seen in shallow areas with little ice cover or on land; 57% of the observations were from areas with a depth of 5 m or less (fig. 4a) and 65% of the bear observations were from areas with 0% ice cover (fig. 4b). the median sst in the areas where polar bears were observed was 2.6°c (fig. 4e). figure 7 kde plots showing observation frequencies of polar bears around svalbard during 2005–2018, based on (a) number of observations and (b) number of animals observed. black circles mark locations of observations. seasonal visitors harp seals harp seal observations were most frequent in northern svalbard, especially in liefdefjorden and areas around moffen and at the sea-ice edge north of svalbard (fig. 8a). however, on account of one observation of a large group of 10 000 harp seals, the highest frequency of observations in terms of number of animals was around 76°n, off the southern tip of spitsbergen (fig. 8b). harp seals were observed further away from the coastline than the resident species (median = 19 km; fig. 4c) and far from tidewater glacier fronts (median = 42 km; fig. 4d). they were observed in deep water; 64% of the observations were from areas ≥ 100 m and 34% were from areas ≥ 200 m (fig. 4a). ssts where harp seals were observed were cold (median = 2.0°c; fig. 4e), but ice concentrations were generally light, with 60% of observation in areas with ≤ 10% ice cover and only 10% of observations in areas with ≥ 70% ice cover (fig. 4b). figure 8 kde plots showing observation frequencies of harp seals and hooded seals around svalbard during 2005–2018, based on (a) number of harp seal observations and (b) number of harp seals observed; (c) number of hooded seal observations and (d) number of hooded seals observed. black circles mark locations of observations. hooded seals hooded seals were the least commonly sighted pinniped (n = 45; table 1). the observation frequency, both in terms of observations and number of animals, was highest along the west coast of spitsbergen, especially around the north-west corner (fig. 8c, d). they were found in deep water; 64% of the observations were from areas with depths ≥ 200 m (fig. 4a). hooded seals were observed far from the coast (median = 34 km; fig. 4c) and tidewater glacier fronts (median = 54 km; fig. 4d). they were observed in waters with relatively high ssts (median = 4.2°c; fig. 4e) and little ice cover; 60% of the observations were from areas with no sea ice (fig. 4b). temporal changes: resident species there was no significant increase in mean latitude for walruses (supplementary fig. s1); 0.5% of the observations were made north of 81°n during the recent period and only 0.1% during the early period. frequencies of walrus observations increased in the north-west corner of spitsbergen and in forlandsundet over the study period (fig. 9a), while they decreased slightly at the north end of hinlopenstretet, between spitsbergen and nordaustlandet, and also close to the kapp lee haul-out site (fig. 9a). figure 9 kde plots showing change in observation frequency around svalbard between the early period (2005–2011) and the late period (2012–18) for (a) walruses, (b) ringed seals, (c) bearded seals, (d) harbour seals, (e) polar bears, (f) harp seals and (g) hooded seals. there was no significant increase in the mean latitude of ringed seal observations (supplementary fig. s2), but 7% of the observations were made north of 81°n during the recent period, compared to 2% during the early period. ringed seals were reported more frequently in the central regions of spitsbergen during the recent period, especially in the inner parts of isfjorden (fig. 9b). decreases were seen immediately north of spitsbergen, in hornsund and other parts of southern spitsbergen (fig. 9b). there was a significant increase in the mean latitude at which bearded seals were observed during the study period (0.03° per year; p = 0.045, d.f. = 12; fig. 10a). the greatest increases in the frequency of bearded seal observations from the early to the recent period were seen in the coastal regions in the north-west and the easternmost parts of spitsbergen (fig. 9c). there was also an increase between 81°n and 82°n, north of nordaustlandet at around 20°e (fig. 9c). during the recent period, 5% of the observations were observed north of 81°n, whereas during the early period the proportion of observations this far north was 2%. decreases in the frequency of sightings were seen in southern svalbard, especially in hornsund (fig. 9c). figure 10 latitude of observations for four different species in the mmsdb recorded during 2005–2018; showing (a) bearded seals, (b) harbour seals, (c) polar bears and (d) harp seals. boxplots show values between the 25th and the 75th percentile within boxes that are divided by the median. vertical lines outside the boxes extend to the maximum and the minimum values up to 1.5 times higher or lower than the upper and lower quartile. circles represent outliers, more than 1.5 times higher or lower than the upper and lower quartile. linear regression of the mean for each year is displayed as a black line together with the r2 value for the regression in the top left corner. numbers above or below error bars depict sample sizes. there was no significant trend in the mean latitude for harbour seal observations during the study period (fig. 10b) although latitude accounted for approximately 20% of the variance in location through time. harbour seals were observed more often in the north-westernmost fjords on spitsbergen, while there was a decrease in sightings at the north end of prins karls forland (fig. 9d). there was a significant increase in mean latitude at which polar bears were observed during the study period (0.06° per year; p = 0.013, d.f. = 12; fig. 10c). the proportions of observations made north of 81°n were 9% during the recent period and 2% during the early period. the observation frequency of polar bears increased in the central parts of spitsbergen, especially in isfjorden and on prins karls forland (fig. 9e). there were also increases in areas in the north, east and south-east of nordaustlandet (fig. 9e). decreases were seen in north-central and southern spitsbergen and in the vicinity of hopen (fig. 9e). temporal changes: seasonal visitors there was a significant increase in the mean latitude at which harp seals were observed during the study period (0.12° per year; p = 0.0081, d.f. = 12; fig 10d). observation frequency increased north of svalbard during the recent period compared to the early period (24% of observations compared to 6% of observations), especially at around 81°n, off the coast of nordaustlandet (fig. 9f). there was no significant latitudinal shift for hooded seals observations (supplementary fig. s3). the observation frequency of hooded seals increased off the coast of south spitsbergen, at around 77°n and 15°e and north of svalbard around 81°n and between 10°e and 22°e, while it decreased in eastern svalbard at around 79°n and 8°e (fig. 9g). discussion this study was based on data that was largely acquired via ‘citizen science’. using the mmsdb made it possible to map the spatial and temporal distribution of pinnipeds and polar bears in svalbard during an extended period, throughout much of the svalbard archipelago and compare trends in distribution over time. this study joins a growing list of successful applications of this type of data to monitoring distribution and habitat use of marine mammal populations across the world (tonachella et al. 2012; lodi & tardin 2018; storrie et al. 2018; larue et al. 2020; stephenson et al. 2020). however, using data acquired by citizen science does mean accepting some biases. for example, there are no real measures of sighting effort though the routes taken by the reporting vessels, which generally follow the same path each year (see storrie et al. 2018), with circumnavigation of the main island in the archipelago, spitsbergen, being the most commonly travelled path. additionally, there is a risk of misidentification of species—young ringed and harbour seals in the water can be particularly challenging to differentiate—though the guides on marine cruise ship are generally very good naturalists. another problem arises with observations of groups of animals, especially when numbers are high. generally, reports of group numbers appeared to be crudely estimated when group size exceeded circa 20 animals; it is impossible to know the error margins of such observations. another clear bias in the data is species popularity (preference) and predictability/sightability. tour operators target known walrus haul-out sites because of their predictability and popularity, and they spend a lot of search effort looking for polar bears. the popularity of these charismatic megafauna species results in observations of these two species being over-represented in the database compared to less visible, less spatially predictable or less ‘flashy’ species. smaller pinnipeds, for example, are less likely to be recorded consistently, even if they are sighted. given the biases discussed above, this sort of sighting data should not be used to assess relative abundance. analyses must be kept to simple distributional assessments such as those reported herein, considering trends in reporting frequency when doing time series comparisons. kdes for the number of animals were plotted in this study to get an idea of where the different species concentrate. but given uncertainties regarding actual group sizes for social species, only observations were used in the assessment of habitat characteristics and possible distributional changes through time. another caveat to be mentioned when interpreting the results is that when observations are being reported to the mmsdb, the coordinates of the vessels at the time of observation are sometimes reported instead of the actual coordinates of the animal, so fine-scaled spatial analyses should not be attempted with this type of data. the kdes for walruses highlight their tendency to use coastal haul-outs during summer. walruses were seen very close to shore, often around known terrestrial haul-out sites, and over 90% of the observations occurred in areas shallower than 100 m. these findings are consistent with the results of previous studies that have shown that walruses occupy coastal waters during summer in the svalbard area, occupying shallow waters where mollusc beds occur and hauling out on land approximately 25% of the time (gjertz & wiig 1992; freitas et al. 2009; hamilton, kovacs et al. 2015). the walrus population in svalbard is recovering from historical overharvesting and as their numbers are increasing, they are spreading back through their earlier range, expanding the number of haul-out areas they use (kovacs et al. 2014; mosj 2019). observation frequencies in the current study were high around previously identified haul-out sites, for example, on prins karls forland, north-western spitsbergen, moffen and torellneset (gjertz & wiig 1994; lydersen et al. 2008; kovacs et al. 2014), while individual animal-based observations were highest around storøya and kvitøya in the north-east of the archipelago, where herds tend to be much larger (gjertz & wiig 1994; kovacs et al. 2014; øren et al. 2018). observations of ringed seals in this study took place throughout the archipelago, though the majority of sightings and the greatest numbers of animals being seen close to the coast, especially where tidewater glaciers occur. however, ringed seals were also seen up to 200 km offshore in areas where there was drifting sea ice. ringed seals were, perhaps not surprisingly, the most ice-affiliated resident species in svalbard in this study, with only 40% of the observations of this species classified as open-water sightings. ringed seals are known to have a sympatric lifestyle year-round (mclaren 1958). in svalbard, ringed seals nurse their pups and offspring on land-fast ice, while in the broader barents sea region they also use drift ice as a birthing platform (lydersen 1998; wiig et al. 1999). adult animals that breed in the fjords remain in their breeding areas throughout the year, while most young animals move offshore after the moulting period to the ice edge during the summer and autumn for foraging (freitas et al. 2008; hamilton, lydersen et al. 2015; hamilton et al. 2016; hamilton et al. 2019). tidewater glacier fronts are known hotspots for marine mammal and seabird foraging, because upwellings created by katabatic winds coming down from the glaciers and, to a lesser degree, subglacial discharge of freshwater cause concentrations of zooplankton and fish close to the glacier fronts (hartley & fisher 1936; lydersen et al. 2014; sundfjord et al. 2017). ringed seals made up 5–10% of all recorded observations in all years of the study. during two unusual ice-years (2007 and 2008) when polar pack-ice lay along the north-west corner and north coast, relatively large numbers of ringed seals were seen hauled out on this ice in the summer, inflating the numbers of animals in those years for this relatively shy seal that spends most of its time in the water. bearded seals were observed most commonly close to land in shallow areas, deep into fjords along the west and north coasts of spitsbergen, which is in keeping with their benthic foraging habits and strong affinity for ice when resting (e.g., gjertz et al. 2000b; hamilton et al. 2018, 2019). however, some bearded seals were seen in pack ice areas up to 300 km offshore north of svalbard, but still over the continental shelf (gjertz et al. 2000b; hindell et al. 2012). similar to ringed seals, bearded seals were often observed close to tidewater glacier fronts. hamilton et al. (2019) compared the habitat use of ringed seals and bearded seals in kongsfjorden and concluded that ringed seals have a much higher probability of hauling out during summer, which suggests a conflict with what was found in this study. but it is likely the shy nature of ringed seals, which respond to ships more readily by terminating a haul-out session, dictates their respective sighting rates (kovacs & lydersen 2006). additionally, bearded seals are much larger and darker than ringed seals, making them easier to detect at greater distances when they are resting on ice, creating a potential bias in the numbers seen. harbour seals were observed very close to the shore and at a high frequency around north-western spitsbergen in this study. this is very much in line with previous studies that have found harbour seals in svalbard to be tightly linked to the coast, occupying waters over the shelf (blanchet et al. 2014, hamilton et al. 2014). however, the current study shows that harbour seals are observed with increasing frequencies in the fjords and close to tidewater glacier fronts along the west coast of spitsbergen, contrary to what has been reported from tracking studies (blanchet et al. 2014). there were relatively few observations of harbour seals around prins karls forland, which had earlier been identified as the most important area for the local harbour seal population (reder et al. 2003; hamilton et al. 2014). the reason for the low observation frequency around prins karls forland in this study is most probably that boats simply travel within forlandsundet, east of prins karls forland, which is the main haul-out area for harbour seals in svalbard, and seldom close to the west coast of the island because it is a protected bird reserve during the summer months. there were three single-animal observations of harbour seals on the east coast of spitsbergen in this study. harbour seals have been observed in the east of spitsbergen in the past, but they are rare (henriksen et al. 1997). one of the observations on edgeøya was of an animal hauled out on a rock; a behaviour typical for harbour seals. however, this behaviour has in recent years also been observed for ringed seals in a few specific sites (lydersen et al. 2017), which is a common species in eastern svalbard. in the current study, 64% of the observations of harbour seals were from ice free waters, while only 1% of the observations were from areas with more than 40% ice, making them the least ice associated pinniped in svalbard. this is consistent with tracking studies showing that harbour seals in svalbard avoid areas with more than 50% ice cover (blanchet et al. 2014). harbour seals were the species in this study that had the highest proportion of observations in shallow areas and/or on land. only a small percentage of the harbour seal observations in the mmsdb were from areas deeper than 100 m, which is consistent with previous studies (krafft et al. 2002; blanchet et al. 2014). most polar bear observations in this study were close to, or on land in north-western spitsbergen. this is consistent with the findings of aars et al. (2017), who found that the density of bears on land is higher than that of bears on pack ice around svalbard. polar bears in this study also had high observation frequencies around the easternmost part of spitsbergen and edgeøya, and ice-covered areas north of nordaustlandet. hamilton et al. (2017) showed that polar bears spent less time in association with tidewater glacier fronts during summer in 2010–13 than during the period 2002–04. consequently, they also spent less time associated with ringed seals, their preferred prey, during the summer months (hamilton et al. 2017). consistently, polar bears in this study were observed at a greater median distance from tidewater glacier fronts than the resident phocid seals. polar bears are known to be largely solitary with the exception of mother and cub groups and the short liaison between adult females and males during the mating season (rode & stirling 2018). but, some observations of polar bears included up to 20 individual animals in this study. these concentrations of animals (10 or more bears) were made either around whale or walrus carcasses, or around walrus resting sites. high concentrations of food, such as stranded whale carcasses, are known to result in such polar bear hotspots (lønø 1970; larsen 1986). it is possible that such concentrations of bears are becoming more common as the sea-ice declines reduce their range (laidre et al. 2018). harp seals were observed in high frequencies north of svalbard and in hinlopenstretet. these two areas have not been described as particularly important for harp seals previously (folkow et al. 2004). the increasing presence of harp seals in these areas is likely a result of the retreating summer sea ice edge and increased inflow of atlantic water to the region, opening up these areas for both harp seals and their main prey, capelin (mallotus villosus) (ingvaldsen & gjøsæter 2013). harp seals are a very social species, sometimes occurring in the thousands, as seen in this study. harp seals move into the barents sea seasonally from both the greenland sea and the white sea stocks following the capelin distribution and feeding along the ice edge during the summer months (haug et al. 1994; folkow et al. 2004; nordøy et al. 2008). harp seals in this study were generally observed further from the coast relative to the resident species and in waters with low sst and relatively high sea-ice concentrations, consistent with their affinity to the sea-ice edge. the yearly mean latitude of harp seal observations increased significantly, and observation frequencies increased north and east of the svalbard archipelago. this is likely a consequence of the fact that increased water temperatures since the early 2000s have markedly reduced the average sea-ice concentration north and east of svalbard compared to the 1990s (isaksen et al. 2016). most of the hooded seal observations in this study were made off the west and north coasts of svalbard. these areas have previously been identified as foraging grounds during both summer and winter for hooded seals from the greenland sea stock (folkow et al. 1996; folkow & blix 1999; vacquie-garcia et al. 2017). hooded seals in this study were the species observed with the highest median distance from the coast and the highest proportion of observations in areas ≥ 200 m deep. this is consistent with them being a relatively deep diving species that feeds pelagically at shelf breaks and along the sea-ice edge (folkow & blix 1999; vacquie-garcia et al. 2017). hooded seals were observed in areas with relatively high median sst (4.2°c), compared to the other species. though surprising, this finding is similar to a satellite tracking study of hooded seals in the north-east atlantic that showed that this species seemed to associate with ssts ≥ 4°c (vacquie-garcia et al. 2017). the low number of observations of hooded seals during most years in this study disallows conclusions being drawn regarding potential distribution shifts for this species. except for the harbour seal, all species in this study were observed north of 81°n, with higher frequencies of sightings in northern areas during the recent period, when compared to the early period. this is probably a reflection of the location of the northern sea-ice edge, which has been retreating rapidly during the last three decades (onarheim et al. 2014; walsh et al. 2017; lebedev et al. 2019). the ice edge is a highly productive area during spring, summer and autumn and is in many regards a hotspot for marine fauna (sakshaug & skjoldal 1989). harp seals follow the ice edge in the northern barents sea during summer and autumn, feeding pelagically and occasionally hauling out on the ice (haug et al. 1994; smith & stirling 2019), a habitat that they share with ringed seals (wathne et al. 2000; freitas et al. 2008; hamilton, lydersen et al. 2015). ringed seals that undertake offshore feeding migrations prefer sea-ice concentrations close to 50% and prefer highly concentrated ice (80–100%) over ice-free waters or waters with low sea-ice concentrations (lone et al. 2019). in line with the results of this study, hamilton, lydersen et al. (2015) found that ringed seals feeding offshore during the period 2010–12 travelled on average 1° further north than they did during 2002–03 before they reached ice. there was a slight northward trend in latitude for bearded seal observations. the kde plots also showed relative changes in observation frequency between the early and recent periods, for example, a decrease around hornsund and an increase around north-western spitsbergen. much like ringed seals, bearded seals are ice-associated year-round, throughout their circumpolar distribution (simpkins et al. 2003; lydersen et al. 2014; cameron et al. 2018; hamilton et al. 2019); and decreases in both sea ice coverage and days of land-fast ice have been recorded between 2000 and 2014 in hornsund and isfjorden (muckenhuber et al. 2016). it is possible that bearded seals have shifted their distribution from fjords in southern and western spitsbergen to fjords in the northern part of spitsbergen, where ice conditions have historically been more stable (smith & lydersen 1991). harbour seal observations were more common in the north-western fjords (smeerenburgfjorden and kongs-fjorden) during the recent period, but there was no significant northward trend for observations of this species, which is associated with the coast and not the drifting ice. the proportion of harbour seal observations comprised an increment from only < 1–2% of the total number of observations, during the first four years to 5–10% during the last half of the study. harbour seals appear to be expanding their range and are increasingly found in the fjords in western spitsbergen, a likely consequence of the increased presence of atlantic prey species following an increase in the inflow of warm atlantic water from the west spitsbergen current into these areas (tverberg et al. 2014; brand & fischer 2016). this could lead to competition for resources between harbour seals and ringed seals (in particular), as they share similar foraging strategies (gjertz, lydersen et al. 2001; andersen et al. 2004; bengtsson et al. 2020). comparative studies of habitat use of the two species in fjords where their distributions overlap should be conducted in the near future. the latitude of polar bear observations increased significantly and more bear sightings occurred in central areas along the coast of spitsbergen and, north and east of nordaustlandet. this corresponds well with findings of a study by lone et al. (2018) that reported that the average number of days with suitable habitat related to sea ice for polar bears had increased in these areas during 2011–15 compared to 1992–96. that study also found a general decrease in days with suitable habitat in most other regions (lone et al. 2018) consistent with the decreases of observation frequency seen in this study. despite the lack of standardization of effort and a few other inherent biases, citizen science sighting programmes provide a cost-effective means to collect information regarding distributions of species through time, which are particularly useful at this time for identifying climate change impacts on ecosystems. acknowledgements the authors thank the norwegian coast guard, the imr, the association of arctic expedition cruise operators, the governor of svalbard’s field teams and all others who contributed observations to the mmsdb. siri uldal developed the software frames for the mmsdb. oddveig ørvoll created the map of the study region. claude joiris and an anonymous reviewer provided comments that helped us improve the manuscript. references aars j., marques t.a., lone k., andersen m., wiig ø., bardalen fløystad i.m., hagen s.b. & buckland s.t. 2017. the number and distribution of polar bears in the western barents sea. polar research 36, article no. 1374125, doi: 10.1080/17518369.2017.1374125. andersen s.m., lydersen c., grahl-nielsen o. & kovacs k.m. 2004. autumn diet of harbour seals (phoca vitulina) at prins karls forland, svalbard, assessed via scat and fatty-acid analyses. canadian journal of zoology 82, 1230–1245, doi: 10.1139/z04-093. bengtsson o., lydersen c., kovacs k.m. & lindström u. 2020. ringed seal (pusa hispida) diet on the west coast of spitsbergen, svalbard, norway: during a time of ecosystem change. polar biology 43, 773–788, doi: 10.1007/s00300-020-02684-5. blanchet m.a., lydersen c., ims r.a., lowther a.d. & kovacs k.m. 2014. harbour seal phoca vitulina movement patterns in the high-arctic archipelago of svalbard, norway. aquatic biology 21, 167–181, doi: 10.3354/ab00580. brand m. & fischer p. 2016. species composition and abundance of the shallow water fish community of kongsfjorden, svalbard. polar biology 39, 2155–2167, doi: 10.1007/s00300-016-2022-y. cameron m.f., frost k.j., ver hoef j.m., breed g.a., whiting a.v., goodwin j. & boveng p.l. 2018. habitat selection and seasonal movements of young bearded seals (erignathus barbatus) in the bering sea. plos one 13(2), e0192743, doi: 10.1371/journal.pone.0192743. chacón j.e. & duong t. 2018. multivariate kernel smoothing and its applications. boca raton, fl: crc press. derocher a.e., wiig ø. & andersen m. 2002. diet composition of polar bears in svalbard and the western barents sea. polar biology 25, 448–452, doi: 10.1007/s00300-002-0364-0. descamps s., aars j., fuglei e., kovacs k.m., lydersen c., pavlova o., pedersen å.ø., ravolainen v. & strøm h. 2017. climate change impacts on wildlife in a high arctic archipelago—svalbard, norway. global change biology 23, 490–502, doi: 10.1111/gcb.13381. durner g.m., douglas d.c., nielson r.m., amstrup s.c., mcdonald t.l., stirling i., mauritzen m., born e.w., wiig ø., deweaver e., serreze m.c., belikov s.e., holland m.m., maslanik j., aars j., bailey d.a. & derocher a.e. 2009. predicting 21st‐century polar bear habitat distribution from global climate models. ecological monographs 79, 25–58, doi: 10.1890/07-2089.1. folkow l.p. & blix a.s. 1999. diving behaviour of hooded seals (cystophora cristata) in the greenland and norwegian seas. polar biology 22, 61–74, doi: 10.1007/s003000050391. folkow l.p., mårtensson p.e. & blix a.s. 1996. annual distribution of hooded seals (cystophora cristata) in the greenland and norwegian seas. polar biology 16, 179–189, doi: 10.1007/bf02329206. folkow l.p., nordøy e.s. & blix a.s. 2004. distribution and diving behaviour of harp seals (pagophilus groenlandicus) from the greenland sea stock. polar biology 27, 281–298, doi: 10.1007/s00300-004-0591-7. fossheim m., primicerio r., johannesen e., ingvaldsen r.b., aschan m.m. & dolgov a.v. 2015. recent warming leads to a rapid borealization of fish communities in the arctic. nature climate change 5, 673–677, doi: 10.1038/nclimate2647. freitas c., kovacs k.m., ims r.a., fedak m.a. & lydersen c. 2008. ringed seal post-moulting movement tactics and habitat selection. oecologia 155, 193–204, doi: 10.1007/s00442-007-0894-9. freitas c., kovacs k.m., ims r.a., fedak m.a. & lydersen c. 2009. deep into the ice: over-wintering and habitat selection in male atlantic walruses. marine ecology progress series 375, 247–261, doi: 10.3354/meps07725. gjertz i., griffiths d., krafft b.a., lydersen c. & wiig ø. 2001. diving and haul-out patterns of walruses odobenus rosmarus on svalbard. polar biology 24, 314–319, doi: 10.1007/s003000000211. gjertz i., kovacs k.m., lydersen c. & wiig ø. 2000a. movements and diving of adult ringed seals (phoca hispida) in svalbard. polar biology 23, 651–656, doi: 10.1007/s003000000143. gjertz i., kovacs k.m., lydersen c. & wiig ø. 2000b. movements and diving of bearded seal (erignathus barbatus) mothers and pups during lactation and post-weaning. polar biology 23, 559–566, doi: 10.1007/s003000000121. gjertz i., lydersen c. & wiig ø. 2001. distribution and diving of harbour seals (phoca vitulina) in svalbard. polar biology 24, 209–214, doi: 10.1007/s003000000197. gjertz i. & wiig ø. 1992. feeding of walrus odobenus rosmarus in svalbard. polar record 28, 57–59, doi: 10.1017/s0032247400020283. gjertz i. & wiig ø. 1994. past and present distribution of walruses in svalbard. arctic 47, 34–42, doi: 10.14430/arctic1269. hamilton c.d., kovacs k.m., ims r.a., aars j. & lydersen c. 2017. an arctic predator–prey system in flux: climate change impacts on coastal space use by polar bears and ringed seals. journal of animal ecology 86, 1054–1064, doi: 10.1111/1365-2656.12685. hamilton c.d., kovacs k.m. & lydersen c. 2015. year-round haul-out behaviour of male walruses odobenus rosmarus in the northern barents sea. marine ecology progress series 519, 251–263, doi: 10.3354/meps11089. hamilton c.d., kovacs k.m. & lydersen c. 2018. individual variability in diving, movement and activity patterns of adult bearded seals in svalbard, norway. scientific reports 8, article no. 16988, doi: 10.1038/s41598-018-35306-6. hamilton c.d., kovacs k.m. & lydersen c. 2019. sympatric seals use different habitats in an arctic glacial fjord. marine ecology progress series 615, 205–220, doi: 10.3354/meps12917. hamilton c.d., lydersen c., ims r.a. & kovacs k.m. 2014. haul-out behaviour of the world’s northernmost population of harbour seals (phoca vitulina) throughout the year. plos one 9(1), e86055, doi: 10.1371/journal.pone.0086055. hamilton c.d., lydersen c., ims r.a. & kovacs k.m. 2015. predictions replaced by facts: a keystone species’ behavioural responses to declining arctic sea ice. biology letters 11, article no. 20150803, doi: 10.1098/rsbl.2015.0803. hamilton c.d., lydersen c., ims r.a. & kovacs k.m. 2016. coastal habitat use by ringed seals pusa hispida following a regional sea-ice collapse: importance of glacial refugia in a changing arctic. marine ecology progress series 545, 261–277, doi: 10.3354/meps11598. hartley c.h. & fisher j. 1936. the marine foods of birds in an inland fjord region in west spitsbergen. part 2. birds. the journal of animal ecology 5, 370–389, doi: 10.2307/1041. haug t., nilssen k.t., ien n. & potelov v. 1994. seasonal distribution of harp seals (phoca groenlandica) in the barents sea. polar research 13, 163–172, doi: 10.1111/j.1751-8369.1994.tb00446.x. henriksen g., gjertz i. & kondakov a. 1997. a review of the distribution and abundance of harbor seals, phoca vitulina, on svalbard, norway, and in the barents sea. marine mammal science 13, 157–163, doi: 10.1111/j.1748-7692.1997.tb00622.x. hindell m.a., lydersen c., hop h. & kovacs k.m. 2012. pre-partum diet of adult female bearded seals in years of contrasting ice conditions. plos one 7(5), e38307, doi: 10.1371/journal.pone.0038307. ingvaldsen r.b. & gjøsæter h. 2013. responses in spatial distribution of barents sea capelin to changes in stock size, ocean temperature and ice cover. marine biology research 9, 867–877, doi: 10.1080/17451000.2013.775450. ipcc 2014. climate change 2014: synthesis report. geneva: intergovernmental panel on climate change. isaksen k., nordli ø., førland e.j., łupikasza e., eastwood s. & niedźwiedź t. 2016. recent warming on spitsbergen—influence of atmospheric circulation and sea ice cover. journal of geophysical research—atmospheres 121, 11–913, doi: 10.1002/2016jd025606. jakobsson m., mayer l., coakley b., dowdeswell j.a., forbes s., fridman b., noormets r., pedersen r., rebesco m., schenke h.w., zarayskaya y., accettella d., armstrong a., anderson r.m., bienhoff p., camerlenghi a., church i., edwards m., gardner j.v., hall j.k., hell b., hestvik o., kristoffersen y., christian m., mohammad r., mosher d., ngheim s.v., pedrosa m.t., travaglini p.g. & weatherall p. 2012. the international bathymetric chart of the arctic ocean (ibcao) version 3.0. geophysical research letters 39, l12609, doi: 10.1029/2012gl052219. kohler j., könig m., nuth c. & villaflor g. 2018. svalbard tidewater glacier front database. 2.07. data set. tromsø, norway: norwegian polar institute. doi: 10.21334/npolar.2018.7cd67b1a. kovacs k.m., aars j. & lydersen c. 2014. walruses recovering after 60+ years of protection in svalbard, norway. polar research 33, article no. 26034, doi: 10.3402/polar.v33.26034. kovacs k.m. & lydersen c. 2006. birds and mammals of svalbard. polar handbook 13. tromsø: norwegian polar institute. kovacs k.m., lydersen c., overland j.e. & moore s.e. 2011. impacts of changing sea-ice conditions on arctic marine mammals. marine biodiversity 41, 181–194, doi: 10.1007/s12526-010-0061-0. krafft b.a., lydersen c., gjertz i. & kovacs k.m. 2002. diving behaviour of sub-adult harbour seals (phoca vitulina) at prins karls forland, svalbard. polar biology 25, 230–234, doi: 10.1007/s00300-001-0330-2. laidre k.l., born e.w., atkinson s.n., wiig ø., andersen l.w., lunn n.j., dyck m., regehr e.v., mcgovern r. & heagerty p. 2018. range contraction and increasing isolation of a polar bear subpopulation in an era of sea‐ice loss. ecology and evolution 8, 2062–2075, doi: 10.1002/ece3.3809. laidre k.l., stern h., kovacs k.m., lowry l., moore s.e., regehr e.v., fergusson s.h., wiig ø., boveng p., angliss r.p., born e.w., litovka d., quakenbush l., lydersen c., vongraven d. & ugarte f. 2015. arctic marine mammal population status, sea ice habitat loss, and conservation recommendations for the 21st century. conservation biology 29, 724–737, doi: 10.1111/cobi.12474. larsen t. 1986. population biology of the polar bear (ursus maritimus) in the svalbard area. oslo: norwegian polar institute. larue m.a., ainley d.g., pennycook j., stamatiou k., salas l., nur n., stammerjohn s. & barrington l. 2020. engaging “the crowd” in remote sensing to learn about habitat affinity of the weddell seal in antarctica. remote sensing in ecology and conservation 6, 70–78, doi: 10.1002/rse2.124. lebedev s.a., kostianoy a.g. & popov s.k. 2019. satellite altimetry of sea level and ice cover in the barents sea. ecologica montenegrina 25, 26–35, doi: 10.37828/em.2019.25.3. leclerc l-m., lydersen c., haug t., bachmann l., fisk a. & kovacs k. 2012. a missing piece in the arctic food web puzzle? stomach contents of greenland sharks sampled in svalbard, norway. polar biology 45, 1197–1208, doi: 10.1007/s00300-012-1166-7. lind s., ingvaldsen r.b. & furevik t. 2018. arctic warming hotspot in the northern barents sea linked to declining sea-ice import. nature climate change 8, 634–639, doi: 10.1038/s41558-018-0205-y. lodi l. & tardin r. 2018. citizen science contributes to the understanding of the occurrence and distribution of cetaceans in southeastern brazil—a case study. ocean & coastal management 158, 45–55, doi: 10.1016/j.ocecoaman.2018.03.029. lone k., hamilton c.d., aars j., lydersen c. & kovacs k.m. 2019. summer habitat selection by ringed seals (pusa hispida) in the drifting sea ice of the northern barents sea. polar research 38, article no. 3483, doi: 10.33265/polar.v38.3483. lone k., merkel b., lydersen c., kovacs k.m. & aars j. 2018. sea ice resource selection models for polar bears in the barents sea subpopulation. ecography 41, 567–578, doi: 10.1111/ecog.03020. lønø o. 1970. the polar bear (ursus maritimus phipps) in the svalbard area. oslo: norwegian polar institute. lowther a.d., kovacs k.m., griffiths d. & lydersen c. 2015. identification of motivational state in adult male atlantic walruses inferred from changes in movement and diving behavior. marine mammal science 31, 1291–1313, doi: 10.1371/journal.pone.0124754. lydersen c. 1998. status and biology of ringed seals (phoca hispida) in svalbard. nammco scientific publications 1, 46–62, doi: 10.7557/3.2980. lydersen c., aars j. & kovacs k.m. 2008. estimating the number of walruses in svalbard from aerial surveys and behavioural data from satellite telemetry. arctic 61, 119–128, doi: 10.14430/arctic31. lydersen c., angantyr l.a., wiig ø. & øritsland t. 1991. feeding habits of northeast atlantic harp seals (phoca groenlandica) along the summer ice edge of the barents sea. canadian journal of fisheries and aquatic sciences 48, 2180–2183, doi: 10.1139/f91-257. lydersen c., assmy p., falk-petersen s., kohler j., kovacs k.m., reigstad m., steen h., strøm h., sundfjord a., varpe ø., walczowski w., węsławski j.m. & zajaczkowski m. 2014. the importance of tidewater glaciers for marine mammals and seabirds in svalbard, norway. journal of marine systems 129, 452–471, doi: 10.1016/j.jmarsys.2013.09.006. lydersen c. & gjertz i. 1986. studies of the ringed seal (phoca hispida schreber 1775) in its breeding habitat in kongsfjorden, svalbard. polar research 4, 57–63, doi: 10.3402/polar.v4i1.6920. lydersen c., gjertz i. & węsławski j.m. 1989. stomach contents of autumn-feeding marine vertebrates from hornsund, svalbard. polar record 25, 107–114, doi: 10.1017/s0032247400010408. lydersen c., vaquie-garcia j., lydersen e., christensen g.n. & kovacs k.m. 2017. novel terrestrial haul-out behaviour by ringed seals (pusa hispida) in svalbard, in association with harbour seals (phoca vitulina). polar research 36, article no. 1374124, doi: 10.1080/17518369.2017.1374124. maslanik j.a., fowler c., stroeve j., drobot s., zwally j., yi d. & emery w. 2007. a younger, thinner arctic ice cover: increased potential for rapid, extensive sea‐ice loss. geophysical research letters 34, l24501, doi: 10.1029/2007gl032043. mauritzen m., derocher a.e., wiig ø., belikov s.e., boltunov a.n., hansen e. & garner g.w. 2002. using satellite telemetry to define spatial population structure in polar bears in the norwegian and western russian arctic. journal of applied ecology 39, 79–90, doi: 10.1046/j.1365-2664.2002.00690.x. mclaren i.a. 1958. the biology of the ringed seal, phoca hispida, in the eastern canadian arctic. ottawa: fisheries research board of canada. merkel b., lydersen c., yoccoz n.g. & kovacs k.m. 2013. the world’s northernmost harbour seal population—how many are there? plos one 8(7), e67576, doi: 10.1371/journal.pone.0067576. mosj (environmental monitoring of svalbard and jan mayen) 2019. walrus population. accessed on the internet at http://www.mosj.no/en/fauna/marine/walrus-population.html on 5 march 2020. muckenhuber s., nilsen f., korosov a. & sandven s. 2016. sea ice cover in isfjorden and hornsund, svalbard (2000–2014) from remote sensing data. the cryosphere 10, 149–158, doi: 10.5194/tc-10-149-2016. nasa (national aeronautics and space administration goddard space flight center, ocean ecology laboratory, ocean biology processing group) 2014. moderate-resolution imaging spectroradiometer (modis) aqua 11μm day/night sea surface temperature data. nasa ob.daac. doi: data/10.5067/aqua/modis/l3b/sst/2014. accessed on the internet at https://oceandata.sci.gsfc.nasa.gov/modis-aqua/mapped/monthly/4km/sst/ on 10 october 2019. nordøy e.s., folkow l.p., potelov v., prischemikhin v. & blix a.s. 2008. seasonal distribution and dive behaviour of harp seals (pagophilus groenlandicus) of the white sea–barents sea stock. polar biology 31, article no. 1119, doi: 10.1007/s00300-008-0453-9. nuth c., kohler j., könig m., von deschwanden a., hagen j.o., kääb a., moholdt g. & petterson r. 2013. decadal changes from a multi-temporal glacier inventory of svalbard. the cryosphere 7, 1603–1621, doi: 10.5194/tc-7-1603-2013. onarheim i.h., smedsrud l.h., ingvaldsen r.b. & nilsen f. 2014. loss of sea ice during winter north of svalbard. tellus a 66, article no. 23933, doi: 10.3402/tellusa.v66.23933. øren k., kovacs k.m., yoccoz n.g. & lydersen c. 2018. assessing site-use and sources of disturbance at walrus haul-outs using monitoring cameras. polar biology 41, 1737–1750, doi: 10.1007/s00300-018-2313-6. pörtner h.-o., roberts d.c., masson-delmotte v., zhai p., tignor m., poloczanska e., mintenbeck k., alegría a., nicolai m., okem a., petzold j., rama b. & weyer n.m. (eds.) 2019. the ocean and cryosphere in a changing climate. a special report of the intergovernmental panel on climate change. geneva: intergovernmental panel on climate change. r development core team 2018. a language and environment for statistical computing. vienna: r foundation for statistical computing. reder s., lydersen c., arnold w. & kovacs k.m. 2003. haulout behaviour of high arctic harbour seals (phoca vitulina vitulina) in svalbard, norway. polar biology 27, 6–16, doi: 10.1007/s00300-003-0557-1. rode k. & stirling i. 2018. polar bear: ursus maritimus. in b. würsig et al. (eds.): encyclopedia of marine mammals. pp. 743–746. cambridge, ma: academic press. sakshaug e. & skjoldal h.r. 1989. life at the ice edge. ambio 8, 60–67. serreze m.c. & stroeve j. 2015. arctic sea ice trends, variability and implications for seasonal ice forecasting. philosophical transactions of the royal society a 373, article no. 20140159, doi: 10.1098/rsta.2014.0159. silverman b.w. 1986. density estimation for statistics and data analysis. london: chapman and hall. silvertown j. 2009. a new dawn for citizen science. trends in ecology & evolution 24, 467–471, doi: 10.1016/j.tree.2009.03.017. simpkins m.a., hiruki-raring l.m., sheffield g., grebmeier j.m. & bengtson j.l. 2003. habitat selection by ice-associated pinnipeds near st. lawrence island, alaska in march 2001. polar biology 26, 577–586, doi: 10.1007/s00300-003-0527-7. skoglund e.g., lydersen c., grahl-nielsen o., haug t. & kovacs k.m. 2010. fatty acid composition of the blubber and dermis of adult male atlantic walruses (odobenus rosmarus rosmarus) in svalbard, and their potential prey. marine biology research 6, 239–250, doi: 10.1080/17451000903233755. smith t.g. & lydersen c. 1991. availability of suitable land-fast ice and predation as factors limiting ringed seal populations, phoca hispida, in svalbard. polar research 10, 585–594, doi: 10.3402/polar.v10i2.6769. smith t.g. & stirling i. 2019. predation of harp seals, pagophilus groenlandicus, by polar bears, ursus maritimus, in svalbard. arctic 72, 197–202, doi: 10.14430/arctic68186. spielhagen r.f., werner k., sørensen s.a., zamelszyk k., kandiano e., budeus g., husum k., marchitto t. & hald m. 2011. enhanced modern heat transfer to the arctic by warm atlantic water. science 331, 450–453, doi: 10.1126/science.1197397. stephenson f., goetz k., sharp b.r., mouton t.l., beets f.l., roberts j. macdiarmid a.b., constantine r. & lundquist c.j. 2020. modelling the spatial distribution of cetaceans in new zealand waters. diversity and distributions 26, 495–516, doi: 10.1111/ddi.13035. stirling i. & derocher a.e. 2012. effects of climate warming on polar bears: a review of the evidence. global change biology 18, 2694–2706, doi: 10.1111/j.1365-2486.2012.02753.x. storrie l., lydersen c., andersen m., wynn r.b. & kovacs k.m. 2018. determining the species assemblage and habitat use of cetaceans in the svalbard archipelago, based on observations from 2002 to 2014. polar research 37, article no. 1463065, doi: 10.1080/17518369.2018.1463065. sundfjord a., albretsen j., kasajima y., skogseth r., kohler j., nuth c., skarðhamar j., cottier f., nilsen f., asplin l., gerland s. & torsvik t. 2017. effects of glacier runoff and wind on surface layer dynamics and atlantic water exchange in kongsfjorden, svalbard; a model study. estuarine, coastal and shelf science 187, 260–272, doi: 10.1016/j.ecss.2017.01.015. tonachella n., nastasi a., kaufman g., maldini d. & rankin r.w. 2012. predicting trends in humpback whale (megaptera novaeangliae) abundance using citizen science. pacific conservation biology 18, 297–309, doi: 10.1071/pc120297. tverberg v., nøst o.a., lydersen c. & kovacs k.m. 2014. winter sea ice melting in the atlantic water subduction area, svalbard, norway. journal of geophysical research—oceans 119, 5945–5967, doi: 10.1002/2014jc010013. vacquie-garcia j., lydersen c., biuw m., haug t., fedak m.a. & kovacs k.m. 2017. hooded seal cystophora cristata foraging areas in the northeast atlantic ocean—investigated using three complementary methods. plos one 12(12), e0187889, doi: 10.1371/journal.pone.0187889. vann-sander s., clifton j. & harvey e. 2016. can citizen science work? perceptions of the role and utility of citizen science in a marine policy and management context. marine policy 72, 82–93, doi: 10.1016/j.marpol.2016.06.026. walsh j.e., fetterer f., scott stewart j. & chapman w.l. 2017. a database for depicting arctic sea ice variations back to 1850. geographical review 107, 89–107, doi: 10.1111/j.1931-0846.2016.12195.x. wathne j.a., haug t. & lydersen c. 2000. prey preferences and niche overlap of ringed seals phoca hispida and harp seals p. groenlandica in the barents sea. marine ecology progress series 194, 233–239, doi: 10.3354/meps194233. wiig ø., derocher a.i. & belikov s.e. 1999. ring seal (phoca hispida) breeding in the drifting pack ice of the barents sea. marine mammal science 15, 595–598, doi: 10.1111/j.1748-7692.1999.tb00828.x. 1 (page number not for citation purpose) b o o k r e v i e w review of the life of josé maría sobral: scientist, diarist, and pioneer in antarctica, by mary r. tahan (2018). cham, switzerland: springer international publishing. 336 pp. isbn 978-3-319-67267-0. a very young man, the first argentine to explore and work in antarctica, a man alone in many ways, a man who kept a diary: josé maría sobral (1880–1961) was a member of the swedish south polar expedition (1901–1903) shore party of six men, headed by professor otto nordenskjöld, which worked on snow hill island off the tip of the antarctic peninsula. his presence among the scandinavians was a trade-off for the support of the argentine government, which had supplied food and provisions. sobral, a 21-year-old under-lieutenant in the argentine navy, performed expedition work in meteorology, magnetism and geodesy with diligence and dedication. most of this book consists of his diary during his time in antarctica. there are two chapters of background material and concluding chapters covering sobral’s life after antarctica. author mary r.  tahan, a canadian– american writer and researcher, and one of the international artists selected by the dirección nacional del antártico to perform work on-site in antarctica, has collated the material and provided insightful commentary throughout the diary sections. sobral later wrote an account of his experiences (sobral 1904), but this is the first published work of his expedition diary and daily journal translated into english. an integration of two close translations of the original castilian spanish, the diary is a compelling personal account of the expedition activities, findings and discoveries, including sobral’s private thoughts, intimate observations and real-time recounting of events. as tahan points out in her preface, the diary sheds further light on the importance of this expedition to world knowledge and to antarctic history as well as on the significance of sobral’s role in the expedition. interpersonal problems occurred among the isolated and confined group, resulting from fundamental characteristics of the experience; sustained close personal contact with other individuals in the extreme physical environment of a polar expedition can be cumulatively stressful. sobral wrote: the dogs that are supposed to be the authors of [the dog] qvik’s death have been given a huge beating this morning. how barbaric! as if the animals will understand that it was because of what they did yesterday. it was jonassen’s idea, and, naturally, nordenskjöld approves … at mealtime, ekelöf … serves himself first and then passes to me what’s left … with deep sighs, and this is every day. and many times, after i have served myself, he points out that there is little food… i don’t know how he has the courage to lie to me in my face and tell me that he has treated me well. (p. 192) sobral was the foreigner in the group, the “stepchild of the expedition” (duse 1905: 177, cited in lewander 2007: 181). he communicated with the scientists in english but set himself at once to learn the swedish language. nevertheless, tahan writes that “his isolation haunted him correspondence pat millar, college of arts, law, and education, university of tasmania,130 high street, oatlands, tasmania 7120, australia. e-mail: patricia.millar@utas.edu.au polar research 2019. © 2019 pat millar. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. citation: polar research 2019, 38, 3756, http://dx.doi.org/10.33265/polar.v38.3756 mailto:patricia.millar@utas.edu.au http://creativecommons.org/licenses/by-nc/4.0/ http://dx.doi.org/10.33265/polar.v38.3756 citation: polar research 2019, 38, 3756, http://dx.doi.org/10.33265/polar.v38.35762 (page number not for citation purpose) book review throughout his life—in the navy, in antarctica, in his adopted home of sweden, and in his homeland of argentina” (p. xi). he was the kind of isolated human who sought companionship, mostly with little success. his best friend on the expedition, the american landscape painter frank wilbert stokes (1858–1955), later decided to turn back rather than spend a winter in antarctica. stokes had been the artist member of three peary expeditions to the arctic and greenland from 1892 to 1894, was an advocate for the need for art to complement science and may have had some mentoring effect on the scientists’ photographic work, including sobral’s (millar 2018). with the loss of stokes, sobral’s spirit became even more “disheartened by fatigue and by the frightening isolation of those regions”, as he put it (p. 308). physical discomforts were many and constant. sobral wrote: every day, bodman and i, who are the ones with the upper beds, receive a continuous rain from the ceiling. today, it has been a downpour. we uselessly place blankets and towels against the ceiling, but the water still goes through it, and our beds are real lakes. (p. 167) by the time of their unplanned second winter in antarctica, the men were, as tahan described them, very short on fresh protein … their house was becoming an ice-encrusted, sticky soot-filled, mouldy abode; their clothes were disintegrating on their backs (and feet); and the dogs … were becoming weak with hunger. (p. 185) but even then, sobral could still appreciate the beauty around him: [d]espite the cold, how beautiful is nature in these moments! the sky completely full of stars, and the white of the frozen plain forms a contrast with the black of the basalt cliffs … you can see the pinkish tinge of the aurora to the east, and … on the enormous snowdrift, like a reflection more beautiful than the image itself, you can see the transitions of the delicate tints between red and yellow. (p. 187) his book dos años (sobral 1904) is illustrated with photographs that he took and developed. their poor quality, he wrote, was due to his lack of skill as a photographer, together with physical drawbacks in performing the work and deficiencies in the condition of the photographic equipment. however, author tahan found “quite lovely” (pers. comm., 2 may 2019) a collection of his photographs, many of which were later hand-painted, in the naval archives in buenos aires (estudios históricos navales). the contrast between this extraordinary environmental beauty, dedicated work, hardship and interpersonal struggle make this an absorbing book which would be of great use to readers interested in the heroic age of antarctic exploration and to students of the period. sobral’s diary is an expression of the indomitability of the human spirit. it encapsulates the contemporary idea of antarctica as a crucible, putting men to the ultimate test. references duse s. 1905. bland pingviner och sälar. minnen från svenska sydpolsexpeditionen 1901–1903. (among penguins and seals. memories from the swedish south polar expedition.) stockholm: beijers bokförlagsaktiebolag. lewander l. 2007. to remember and restore the argentine rescuers of the nordenskjöld expedition, 1901–1903. in j. rabassa & m.l. borla (eds.): antarctic peninsula and tierra del fuego: 100 years of swedish–argentine scientific cooperation at the end of the world. pp. 179–194. london: taylor & francis. millar p. 2018. multiple meanings within visual documentation of the swedish south polar expedition (1901–1903): the tension between emotive/aesthetic and analytic/scientific motifs. the polar journal 8, 44–67. sobral j.m. 1904. dos años entre los hielos 1901–1903. (two years in the ice.) buenos aires: tragant. http://dx.doi.org/10.33265/polar.v38.3576 doi:10.3402/polar.v35.29762 r e s e a r c h n o t e scleractinian corals recorded in the argentinean antarctic expeditions between 2012 and 2014, with comments on flabellum (flabellum) areum cairns, 1982 laura schejter,1,2 claudia s. bremec2 & stephen d. cairns3 1 instituto nacional de investigación y desarrollo pesquero, paseo victoria ocampo 1, 7600 mar del plata, argentina 2 consejo nacional de investigaciones cientı́ficas y técnicas, instituto de investigaciones marinas y costeras, mar del plata, argentina 3 department of invertebrate zoology, national museum of natural history, smithsonian institution, washington, dc 20560, usa keywords cold-water corals; antarctica; range extension; bathymetric range extension; scleractinia. correspondence laura schejter, instituto nacional de investigación y desarrollo pesquero, paseo victoria ocampo 1, 7600 mar del plata, argentina. e-mail: schejter@inidep.edu.ar abstract in this contribution, we provide a list of the scleractinian corals recorded during the argentinean antarctic expeditions on board the oceanographic vessel puerto deseado (argentina) in the austral summers in 2012, 2013 and 2014. the identified taxa consist of six solitary species (flabellum impensum, f. flexuosum, f. areum, caryophyllia antarctica, paraconotrochus antarcticus and javania antarctica), recorded from 19 sampling sites located off the antarctic peninsula and south shetland and south orkney islands. we also update the information of f. areum, previously known only from south-west atlantic waters, extending its distribution range to antarctic waters and its upper bathymetric range to 218 m. to access the supplementary material for this article, please see the supplementary files under article tools, online. the term ‘‘coral’’ is a polyphyletic concept to group seven different cnidarian taxa (scleractinia, antipatharia, octocorallia, stylasteridae, milleporidae, two zoanthids and three calcified hydractiniids) having continuous or discontinuous calcium carbonate or horn-like skeletal elements (cairns 2007). cold-water corals are organisms under the spotlight of international conservation organizations and national governments across the world (roberts & cairns 2014). corals are conspicuous components of the antarctic benthos, although they do not usually constitute a high biomass of the benthic community, which is mainly dominated by sponges, echinoderms, tunicates and bryozoans (brey & gerdes 1997). among them, antarctic scleractinians are well-studied organisms that comprise about 17 species distributed mostly off continental antarctica and the antarctic archipelagos (cairns 1982, 1990). additional species have been recorded and described for sub-antarctic waters in southern south america, drake passage and new zealand (cairns 1982, 1995, 2007; cairns & polonio 2013; margolin et al. 2014). the aim of this contribution is to provide a list of the scleractinian corals recorded during argentina’s recent antarctic expeditions in the austral summers, during three research cruises developed during february and march of 2012, january and february of 2013 and february and march of 2014 in the area comprised by the antarctic peninsula, south shetland and south orkney islands. the geo-referenced data we present could contribute to global databases and to marine biodiversity inventories. additionally, we update descriptive information and the distribution range of the cold-water coral flabellum (f.) areum, previously recorded only from sub-antarctic waters. methods specimens from a total of 47 sampled stations (fig. 1) from three antarctic expeditions on board the oceanographic vessel puerto deseado (argentina) were studied. a demersal bottom trawl pilot net (6 m total length, 25 mm mesh on wings and 10 mm in the cod end) was employed, except at three sites at which a blake trawl was used (in 2012). the sampling design and methods were not established for coral sampling procedures. this research is a by-product of general sampling designed for the characterization of demersal fish and macroand megabenthos. polar research 2016. # 2016 l. schejter et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 29762, http://dx.doi.org/10.3402/polar.v35.29762 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/29762/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/29762/0 http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/29762 http://dx.doi.org/10.3402/polar.v35.29762 scleractinian corals were sampled and separated from total catches, except at five stations, where the biomass of the total catch exceeded 150 kg. at these five stations the majority of the benthic organisms was subsampled. specimens were photographed and preserved on board, and subsequently transported, cleaned and identified at the benthos laboratory of the national institute for fisheries research and development (instituto nacional de investigación y desarrollo pesquero), argentina. selected organisms were deposited as voucher specimens at macn (the supplementary file lists expedition codes). specimens were identified considering the following sources: cairns (1982, 1990), cairns & kitahara (2012) and cairns & polonio (2013). results and discussion scleractinian corals were recorded from 19 of the 47 sampling stations (fig. 1, table 1). total catches per station varied from 1.63 kg to 547 kg. a total of 250 living specimens belonging to five solitary species and one additional dead specimen of a sixth species were recovered from the catches. five are common deep-sea species previously recorded for antarctic waters (cairns 1982, 1990), whereas one species represents a new record for antarctic waters, also collected at its shallowest bathymetric range. phylum cnidaria class anthozoa subclass hexacorallia order scleractinia family caryophylliidae genus caryophyllia lamarck, 1801 caryophyllia (caryophyllia) antarctica marenzeller, 1904 material examined. a total of 93 living specimens were recovered in the antarctic peninsula and south orkney islands at six stations during the three expeditions (table 1, figs. 2a, b, 3b). deposited vouchers: macn-in 40275, macn-in 40278, macn-in 40287. remarks. this was the second most abundant scleractinian species collected (after flabellum impensum). the specimens had a conical corallum and a round calice, the largest specimen measuring 17 mm in cd and 26 mm tall, having 84 septa and 14 palar laths. the cd range of the studied specimens was 8�17 mm. the specimens presented the characteristic sinuous septal and palar edges, with rectangular granules and short carinae. this antarctic species was recently recorded from south american waters (cairns & polonio 2013), between 87 and 1620 m. 55 60 65 70 70 60 50 40 longitude (w) antarctic peninsula south shetland is. south orkney is. south america l a tit u d e ( s ) fig. 1 sampling stations of the 2012, 2013 and 2014 argentinean antarctic expeditions. scleractinian corals were collected only at the stations marked with black circles. abbreviations in this article cd: calicular diameter gcd: greater calicular diameter gcd: lcd: ratio of greater to lesser calicular diameters lcd: lesser calicular diameter pd: pedicel diameter macn: museo argentino de ciencias naturales ‘‘bernardino rivadavia,’’ buenos aires, argentina scleractinian corals of the argentinean antarctic expeditions l. schejter et al. 2 (page number not for citation purpose) citation: polar research 2016, 35, 29762, http://dx.doi.org/10.3402/polar.v35.29762 http://www.polarresearch.net/index.php/polar/rt/suppfiles/29762/0 http://www.polarresearch.net/index.php/polar/article/view/29762 http://dx.doi.org/10.3402/polar.v35.29762 table 1 location of the 19 stations where scleractinian corals were collected during the three antarctic argentinean expeditions in 2012, 2013 and 2014. date of collection, latitude, longitude, depth, species identification and number of specimens (in parenthesis) are provided for each site. date lat. (s), long. (w) depth (m) species recorded 20/02/12 64824,74?, 66805,42? 327 caryophyllia antarctica (2), flabellum areum (2), f. impensum (2) 07/03/12 60840,99?, 46814,56? 104 f. impensum (6) 20/02/12 64853,63?, 66820? 404 c. antarctica (1), f. areum (1) 22/02/12 64809,94?, 64827,25? 565 juveniles flabellum sp. (7) 22/02/12 63836,18?, 64821,80? 355 c. antarctica (4) 23/02/12 63843,09?, 61807,40? 142 c. antarctica (1) 05/02/13 61844,30?, 56825? 590 f. impensum (1) 05/02/13 61851,80?, 56833,10? 595 f. impensum (8) 10/02/13 63802,40?, 60839,10? 132 f. impensum (4) 13/02/13 65836,50?, 66836,80? 168 c. antarctica (2), paraconotrochus antarcticus (1), f. flexuosum (2), f. impensum (1), flabellum sp. (2) 16/02/13 64843,80?, 63803,80? 318 f. areum (2), f. flexuosum (4), f. impensum (7), broken flabellum sp. (2) 16/02/13 64841,50?, 63801,60? 343 f. areum (1), f. flexuosum (2) 19/02/14 60828?, 46829? 139 f. impensum (42) 05/03/14 60859?, 46843? 307 f. impensum (1), juveniles flabellum sp. (5), broken flabellum sp. 10/03/14 60853?, 42835? 487 c. antarctica (84), p. antarcticus (1), f. flexuosum (4), f. impensum (4), javania antarctica (1 a ) 20/02/14 60853?, 44833? 218 f. areum (1), f. impensum (17), juveniles flabellum sp. (2) 02/03/14 60855?, 44804? 256 f. flexuosum (1), f. impensum (3) 03/03/14 61825?, 44837? 290 f. impensum (9) 03/03/14 61800?, 46844? 609 f. impensum (2), broken flabellum sp., juveniles flabellum sp. (5) a dead specimen when collected. 20 mm 1 5 m m(b) (a) (c) (h) (i) (j) (f) (l) (d) (e) 2 0 m m 20 mm 35 mm 4 0 m m (k) (g) 10 mm fig. 2 (a, b) caryophyllia antarctica; (c, d) paraconotrochus antarcticus; (e, f) flabellum flexuosum; (g, h) f. areum; (i, j) javania antarctica; (k, l) f. impensum. l. schejter et al. scleractinian corals of the argentinean antarctic expeditions citation: polar research 2016, 35, 29762, http://dx.doi.org/10.3402/polar.v35.29762 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/29762 http://dx.doi.org/10.3402/polar.v35.29762 see cairns (1982, 1990) for a complete description of the species. genus paraconotrochus cairns & parker, 1992 paraconotrochus antarcticus (gardiner, 1929) material examined. two living specimens were recorded from the antarctic peninsula and south orkney islands at two stations (table 1, figs. 2c, d, 3d). deposited voucher: macn-in 40293. remarks. the specimen deposited at macn was collected at the south orkney islands. it was conical, with a round calice of 23 cd, and was 24 mm tall. it had 92 septa and a typical columella composed of many flattened laths. live bryozoans and a lepadomorph crustacean were attached to it. the second specimen, which was collected off the antarctic peninsula, was not available for this study, although we have photographs of it. a complete description of the species and remarks on its biology are given by cairns (1982, 1990). its known bathymetric range is between 87 and 728 m. family flabellidae genus flabellum lesson, 1831 flabellum (flabellum) areum cairns, 1982 material examined. seven living specimens (one broken and six complete specimens) were recorded at five stations located at the west of the antarctic peninsula and south orkney islands (table 1, figs. 2g, h, 3e, 4). deposited vouchers: macn-in 40276, macn-in40282, macn-in 40288, macn-in 40303. diagnosis. the specimens have a trochoid morphology, having a pd between 2.5 and 4 mm. the largest specimen measured 59 mm tall and the smallest, 25 mm. they presented a gcd: lcd ratio between 1.25 and 1.35 (23:17, 39:29, 42:33, 29:23 and 20:16 in the complete specimens), and had between 62 and 104 septa, depending on size. remarks. the sizes of only two of our specimens lay within the known range for the species; the other complete specimens were larger than those previously 55 (a) (c) (e) (f) (d) (b) flabellum impensum caryophyllia antarctica paraconotrochus antarcticusf. flexuosum f. areum javania antarctica longitude (w) l a tit u d e ( s ) 60 60 50 40 65 70 70 60 50 4070 60 50 407060 50 4070 60 50 4070 60 50 4070 55 60 65 70 55 60 65 70 fig. 3 collection sites of the scleractinian species studied: (a) flabellum impensum; (b) caryophyllia antarctica; (c) f. flexuosum; (d) paraconotrochus antarcticus; (e) f. areum; (f) javania antarctica. scleractinian corals of the argentinean antarctic expeditions l. schejter et al. 4 (page number not for citation purpose) citation: polar research 2016, 35, 29762, http://dx.doi.org/10.3402/polar.v35.29762 http://www.polarresearch.net/index.php/polar/article/view/29762 http://dx.doi.org/10.3402/polar.v35.29762 reported (fig. 4). the species resembles f. thouarsii milne edwards & haime 1848 and f. curvatum moseley 1881 (both species recorded only in the south-west atlantic ocean and in sub-antarctic waters), as previously noted by cairns (1982) and cairns & polonio (2013), but can be distinguished from them by its widely spaced septa and its deeper fossa. distribution. the species has previously been recorded in the area between mar del plata and the malvinas islands (off argentina), beyond the shelf break and near tierra del fuego (cairns 1982; cairns & polonio 2013). the bathymetric range of the five stations in which f. areum was recorded varied between 218 and 404 m, all of them shallower than the shallowest limit of 749 m recorded in cairns & polonio (2013). our findings thus extend the distribution range of the species to antarctic waters (up to 648 53,63? s), and our record of a specimen collected at 218 m depth from a station near south orkney islands (table 1) is the shallowest for the species. flabellum (flabellum) flexuosum cairns, 1982 material examined. thirteen specimens were recorded at five stations at the antarctic peninsula and south orkney islands during the 2013 and 2014 expeditions (table 1, figs. 2e, f, 3c). deposited vouchers: macn-in 40279, macn-in 40281, macn-in 40290, macn-in 40291. remarks. the recorded specimens have the typical tall and conical morphology, although some of them were broken. the largest specimen measured was 51 mm tall, had 100 septa and a pd of 4 mm, and had a gcd:lcd of 1.28 (27:21). some of the specimens had bryozoans colonies and serpulid tubes encrusting the theca. the species was recorded from its known bathymetric (101� 659 m) and geographic range in antarctica. see cairns (1982, 1990) for a complete description of the species. flabellum (flabellum) impensum squires, 1962 material examined. a total of 107 adult specimens was sampled in 14 stations of the antarctic peninsula and the south shetland and south orkney islands (table 1, figs. 2k, l, 3a). deposited vouchers: macn-in 40277, macn-in 40280, macn-in 40283, macn-in 40284, macn-in 40285, macn-in 40289, macn-in 40292. remarks. this was the most common and frequent species recorded during the three expeditions. we report the typical flabellate morphology as well as the ceratoid and trochoid morphologies. the largest flabellate corallum was 67 mm tall, had 232 septa, a pd of 3 mm and a gcd:lcd of 2.9 (96:33). many of the sampled specimens had bryozoans colonies encrusting one or both sides of the theca. it is possible that many of the juveniles identified as flabellum sp. at several stations may belong to this species. the species was recorded from its usual bathymetric (46�2260 m) and geographic range in antarctica, and recently, it has also been collected from argentinean coastal waters (schejter & bremec 2015). for a complete description of this species, see cairns (1982, 1990). (a) (c) (e) (f) (d) (b) 35 mm fig. 4 specimens of flabellum areum of bigger sizes than previously recorded. l. schejter et al. scleractinian corals of the argentinean antarctic expeditions citation: polar research 2016, 35, 29762, http://dx.doi.org/10.3402/polar.v35.29762 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/29762 http://dx.doi.org/10.3402/polar.v35.29762 genus javania duncan, 1876 javania antarctica (gravier, 1914) material examined. a dead specimen of j. antarctica, typically ceratoid with a broken reinforced pedicel, was collected near the south orkney islands (table 1, figs. 2i, j, 3f). deposited voucher: macn-in 40286. remarks. the specimen presented a gcd:lcd ratio of 1.26 (53 mm �42 mm) and was 82 mm tall, having about 84 septa. the species was recorded from its known bathymetric (53�1280 m) and geographic range in antarctica. for a complete description of this species, see cairns (1982, 1990). acknowledgements we wish to thank to the crew and participants of the antarctic expeditions that collaborated during sampling procedures. this study was partially supported by the national scientific and technical research council (consejo nacional de investigaciones cientı́ficas y técnicas), the argentinean national antarctic direction, the national institute for fisheries research and development (instituto nacional de investigación y desarrollo pesquero) and pict 2013�0629 (to sl). this is inidep contribution no. 1948. references brey t. & gerdes d. 1997. is antarctic benthic biomass really higher than elsewhere? antarctic science 9, 266�267. cairns s.d. 1982. antarctic and subantarctic scleractinia. research series 34, 1�74. cairns s.d. 1990. antarctic scleractinia. koenigstein: koeltz scientific books. cairns s.d. 1995. the marine fauna of new zealand: scleractinia (cnidaria: anthozoa). new zealand oceanographic institute memoir 103. wellington: national institute of water and atmospheric research. cairns s.d. 2007. deep-water corals: an overview with special reference to diversity and distribution of deep-water scleractinian corals. bulletin of marine science 81, 311�322. cairns s.d. & kitahara m. 2012. an illustrated key to the genera and subgenera of the recent azooxanthellate scleractinia (cnidaria, anthozoa), with an attached glossary. zookeys 227, 1�47. cairns s.d. & polonio v. 2013. new records of deep-water scleractinia off argentina and the falkland islands. zootaxa 3691, 58�86. margolin a.r., robinson l.f., burke a., waller r.g., scanlon k.m., roberts m.l., auro m.e. & van del flierdt t. 2014. temporal and spatial distributions of cold-water corals in drake passage: insights from the last 35,000 years. deep-sea research part ii 99, 237�248. roberts j.m. & cairns s.d. 2014. cold-water corals in a changing ocean. current opinion in environmental sustainability 7, 118�126. schejter l. & bremec c. 2015. first record and range extension of the antarctic coral flabellum (flabellum) impensum in argentinean coastal waters. marine biodiversity records 8, e104, doi: http://dx.doi.org/10.1017/s1755267215000858 scleractinian corals of the argentinean antarctic expeditions l. schejter et al. 6 (page number not for citation purpose) citation: polar research 2016, 35, 29762, http://dx.doi.org/10.3402/polar.v35.29762 http://dx.doi.org/10.1017/s1755267215000858 http://www.polarresearch.net/index.php/polar/article/view/29762 http://dx.doi.org/10.3402/polar.v35.29762 ice-out and freshet fluxes of co2 and ch4 across the air–water interface of the channel network of a great arctic delta, the mackenzie research article ice-out and freshet fluxes of co2 and ch4 across the air–water interface of the channel network of a great arctic delta, the mackenzie jolie a.l. gareis1 & lance f.w. lesack2 1department of geography, simon fraser university, burnaby, bc, canada 2departments of geography & biological sciences, simon fraser university, burnaby, bc, canada abstract carbon dioxide (co2) and methane (ch4) were monitored at five sites spanning the upstream–downstream extent of the mackenzie delta channel network during may 2010, capturing the historically under-sampled ice-out period that includes the rising freshet, peak water levels and the early falling freshet (flood recession). unexpectedly, partial pressures of co2 in the mackenzie river were undersaturated during the rising freshet before water levels peaked, indicating net co2 invasion at instantaneous co2 flux rates (f-co2) ranging from –112 to –258 mg-c m-2 d-1. net co2 invasion was also observed around the time of peak water levels at sites in the middle and outer delta. following peak water levels, the mackenzie river switched to saturation and net co2 evasion (f-co2 from 74 to 177 mg-c m-2 d-1). although the peel river (which flows into the west side of the mackenzie delta) was a strong emitter of co2 (f-co2 from 373 to 871 mg-c m-2 d-1), overall, the mackenzie river and delta were weak emitters of co2 during the 2010 ice-out period. all sites were strong emitters of ch4 during ice-out, however, with the highest evasive fluxes observed in the outer delta when the extent of flooded delta landscape was greatest. estimated aerial fluxes from mackenzie delta channel surfaces during may 2010 ranged from 2.1 to 4.8 gg-c as co2, and 186 to 433 mg-c as ch4. these results provide critical information that can be used to refine gas flux estimates in high-latitude circumpolar river deltas during the relatively under-studied ice-out period. keywords carbon dioxide; methane; greenhouse gas; mackenzie river delta; circumpolar delta; floodplain abbreviations anova: analysis of variance test ddi: distilled de-ionized water dic: dissolved inorganic carbon dom: dissolved organic matter δ13c-dic: stable carbon isotope value of the dic pool f-ch4: methane (ch4) flux f-co2: carbon dioxide (co2) flux f-gas: instantaneous rate of gas flux across the air–water interface hdpe: high-density polyethylene hsd: honestly significant difference test hydat: national water data archive, canada pch4: partial pressure of ch4 pco2: partial pressure of co2 sd: standard deviation citation: polar research 2020, 39, 3528, http://dx.doi.org/10.33265/polar.v39.3528 copyright: polar research 2020. © 2020 j.a.l. gareis & l.f.w. lesack. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 26 june 2020 competing interests and funding: the authors report no conflict of interest. funding for this study was provided by the government of canada international polar year project study of canadian arctic river-delta fluxes, the natural sciences and engineering research council of canada (discovery grant to lfwl, northern research internship to jalg), the polar continental shelf program, the northern scientific training program and the aurora research institute. correspondence to: jolie a.l. gareis, department of geography, simon fraser university, 8888 university drive, burnaby, bc, v5a 1s6, canada. e-mail: jolieg@sfu.ca introduction inland aquatic systems are generally net sources that release co2 and ch4 to the atmosphere. prior studies have quantified the evasion of these globally important carbon-based greenhouse gases from rivers in the tropics (e.g., richey et al. 2002; alin et al. 2011; borges, darchambeau et al. 2015), temperate zones (e.g., raymond et al. 1997; butman & raymond 2011) and boreal regions (e.g., wallin et al. 2010; campeau & del giorgio 2014). while fluxes from north-flowing rivers have been relatively understudied (raymond et al. 2013), prior work on some of the world’s great circumpolar rivers (semiletov 1999; striegl et al. 2012; bussmann 2013; denfeld et al. 2013) and smaller stream networks in alaska (kling et al. 1992; crawford et al. 2013) has indicated that all are generally supersaturated in both co2 and ch4 relative to the atmosphere and therefore act as net carbon sources in the northern landscape. however, these studies have mostly taken place during summer flow conditions, while relatively few have measured fluxes during ice-out or the freshet, when both flow rates and water levels reach an annual maximum. even fewer have investigated flux rates in the productive, lake-rich and seasonally flooded deltas located at the interface between some large circumpolar rivers and the arctic ocean. accurately quantifying co2 and ch4 in these systems is critical because their contribution to total global fluxes may be larger than expected because of gas evasion during ice-out and processes occurring on floodplains during periods of high water. in northern lakes, ice acts as a seasonal barrier that prevents gas exchange with the atmosphere, resulting in over-winter accumulation of co2 and ch4 to very high concentrations that can rapidly escape to the atmosphere during ice-out. rates of evasion during ice-out may be the highest observed all year (phelps et al. 1998; jammet et al. 2017), with up to 66% of the total co2 built up over winter released from scandinavian lakes in just a few days (denfeld et al. 2015). in the northern united states, up to 40% of the total annual ch4 flux from seasonally frozen lakes occurred immediately after ice-out (michmerhuizen et al. 1996). similar to northern lakes, circumpolar rivers and deltas are also ice-covered during each winter. under-ice decomposition of organic matter from the generally large, forested and organic-rich river basins in which these rivers are situated (amon et al. 2012), as well as the large concentrations of dic species derived from groundwater during ice-covered periods (tank et al. 2012; gareis & lesack 2017), together suggest that it is likely that both co2 and ch4 accumulate to high levels under ice in circumpolar rivers and delta channels. it therefore seems probable that evasive fluxes of these gases from circumpolar rivers and delta channel networks would be large and rapid as ice cover is lost at the start of the freshet season, similar to what has been observed in northern lakes. at this time, however, neither the concentrations of these gases under ice nor the magnitude of ice-out fluxes are known for circumpolar lotic systems. this is because the ice-out period is short (generally a few weeks in length) and is characterized by an unstable ice cover, rapidly rising water levels driven by basin snowmelt and moving ice rubble and debris. these conditions make the ice-out period difficult to sample. this critical period has therefore been historically under-sampled in north-flowing river systems, which, in turn, have generally been under-represented in prior estimates of global fluxes of co2 (raymond et al. 2013) and ch4 (bastviken et al. 2011; stanley et al. 2016). rates of co2 and ch4 evasion may be even higher than anticipated in circumpolar great rivers that have a delta between their mainstem and the arctic ocean. circumpolar river deltas are large, complex systems containing numerous distributary channels and seasonally flooded lakes. rising water levels during the early spring freshet cause floodplain lakes to become hydrologically reconnected to delta channels, during which time they are inundated with nutrientand carbon-rich floodwater. during the subsequent period of flood recession, water that was temporarily stored in floodplain lakes and on the wetted floodplain surface drains back into delta channels. this likely moves large amounts of dissolved gases that were generated under ice in the floodplain lakes back into the channels. elevated rates of leaching from submerged soils and vegetation, along with aerobic (strongly co2-producing) or anaerobic (strongly ch4-producing, moderately co2-producing) decomposition of organic matter, make seasonally flooded systems substantial net sources of dissolved gases to both the atmosphere and downstream regions during inundated conditions (marani & alvalá 2007; abril et al. 2014). increasing temperatures in high-latitude river deltas at the start of the open-water season may amplify rates of decomposition, releasing labile carbon from thawed permafrost (vonk et al. 2013; spencer et al. 2015) and mobilizing a pool of easily-respired substrate from the floodplain that may further increase the production of carbon-based greenhouse gases. when taken together, the above-mentioned considerations indicate that high-latitude river deltas may be hotspots of co2 and ch4 evasion in the arctic landscape. the mackenzie delta in the western canadian arctic is an important representative of the global suite of circumpolar river deltas. to address the general lack of direct measurements of co2 and ch4 in these systems, and the particular lack of these measurements during the high-water flooded periods that occur during ice-out, gas concentrations were measured in mackenzie delta channels throughout the 2010 ice-out and freshet. two sources of river flow to the delta were also sampled: the mackenzie river, which supplies the vast majority of the delta’s inflowing water; and the smaller peel river (fig. 1a). our objectives were to quantify fluxes of carbon-based greenhouse gases from channel surfaces in the mackenzie delta during the historically under-sampled ice-out and freshet periods, and to assess downstream changes in gas concentrations and fluxes during the period of peak annual flows and water levels. we expected to find (1) that the delta would remain supersaturated relative to atmospheric gas concentrations throughout the freshet, (2) that partial pressures and fluxes of co2 and ch4 at all sites would be largest when flows and water levels peaked and (3) that fluxes would be greatest at downstream sites because of the addition of dissolved gases generated on the delta floodplain. fig. 1  (a) the mackenzie delta. sampling sites are shown as red dots, towns as yellow squares and environment and climate change canada meteorological stations as pink triangles. (b) the location of the mackenzie delta in the western canadian arctic. (c) a conceptual diagram showing the flood frequency gradient of mackenzie delta floodplain lakes. average river-to-lake connection time during the spring freshet increases with decreasing elevation of an individual lake relative to the river channel (lesack & marsh 2010). thermokarst lakes (here labelled “tk”) are a subset of the high closure lake class formed by thawing ice-rich permafrost that are deeper on average than non-thermokarst lakes. methods study area and sampling sites the mackenzie delta forms the interface between the north-flowing mackenzie river and the beaufort sea basin of the arctic ocean in the western canadian arctic (fig. 1b). it is the second largest river delta in the circumpolar arctic and contains wetlands, numerous anastomosing channels and more than 45 000 shallow floodplain lakes that cover almost half of its 13 000 km2 surface area (emmerton et al. 2007). the mackenzie river and delta are ice-covered for seven to eight months each winter, followed by ice-out and the spring freshet, when the system returns to open-water conditions. the spring freshet is initiated when snowand ice-melt in the 1.8 × 106 km2 mackenzie basin generate an increase in the rate of discharge of more than 3% per day in the mackenzie river upstream of its delta (lesack et al. 2013). peak freshet discharge averages 27 600 m3 s-1 in the mackenzie river (1973–2015 average at the water survey of canada hydrometric gauging station 10lc014 [hydat 2019]), with discharge during the freshet being greater than during any other time of the year. as the freshet moves downstream (north) into the mackenzie delta, it encounters the still-frozen ice cover in delta distributary channels. the mechanical force of the freshet can fracture the ice, which accumulates in delta channels and forms dams that are referred to as “ice jams.” when ice jams restrict the downstream flow of the freshet, already-high water levels in delta channels are further raised (beltaos 2012; lesack et al. 2013), leading to overbank flooding and inundation of the delta landscape. on an average, just less than half (25.8 km3) of the total freshet discharge volume (55.4 km3) moves off-channel and onto the delta floodplain for some amount of time each year (emmerton et al. 2007). lakes on the mackenzie delta floodplain become hydrologically reconnected to delta channels during the freshet, with lakes sitting at lower elevations relative to the nearest distributary channel remaining connected for longer periods than those perched at higher elevations (fig. 1c). five sampling sites were chosen to capture the greatest proportion of flow possible in three delta transects (fig. 1a). the inflow river transect included two sampling sites in the mackenzie and peel rivers upstream of the delta. the mackenzie river has a subarctic nival regime and contributes ca. 95% of the total water flow received by the delta in all seasons (morley 2012), while the peel river has a catchment area of 73 600 km2 and drains a mountainous basin to the west side of the mackenzie delta. the peel contributes a greater percentage of the total flow into the delta during the summer (7.0%) than during the ice-covered winter season (3.1%) (morley 2012). the middle delta transect was sampled at a single site on the middle channel, which carries between 79 and 89% of the total flow in this transect (morley 2012). the outer delta transect was sampled at two sites (langley and reindeer channels) that were upstream of any tidal influence from the beaufort sea, which was confirmed by taking a measurement of conductivity prior to sampling. detailed analysis of the hydrology of the mackenzie delta has suggested that these two channels collectively export approximately 50% of the total delta outflow (morley 2012). all sites were sampled throughout may 2010, when ice-out typically occurs in the network of delta channels, capturing the rising freshet, peak discharge (19 may 2010) and the immediate post-flood high water period (fig. 2). this ice-out period in the channel network occurs at the same time as the ice-out period for lakes on the mackenzie delta floodplain. sampling in the mackenzie river continued throughout the falling freshet until early july 2010. fig. 2  hydrological data for the mackenzie delta system during the 2010 calendar year. discharge (q; m3 s-1) for the (a) mackenzie river (inflow transect) and middle channel (middle delta transect) and (b) peel river (inflow transect), and (c) water level (m a.s.l.) in the two outer delta channels, the reindeer and langley channels. in all graphs, the shaded area delineates the period over which delta-wide gas fluxes (presented in table 2) were estimated (1–31 may 2010). hydrometric data (discharge or water level) were retrieved from hydat (fig. 2). discharge data were available for the mackenzie river, peel river and middle channel site in the middle delta transect. in outer delta channels, complicated interactions between water level and discharge occur during periods of backwater conditions, which are caused by ice jams during the freshet and storm surges during periods of open water (beltaos 2012; blackburn et al. 2015). these conditions prevent the determination of accurate discharge data and, as a result, only water level data were available from hydat for outer delta sites. field sampling water samples for the determination of dic parameters were collected in acid-washed (10% hcl), ddi-rinsed (10 times) and sample rinsed (three times) hdpe bottles. water samples for the determination of gas concentrations were collected in evacuated 160 ml glass serum bottles that were prepared following standard procedures (e.g., hamilton et al. 1994; cunada 2016). serum bottles were soaked for 12 hours (10% hcl), ddi-rinsed (10 times) and allowed to air dry. a total of 8.9 g of kcl was added to each serum bottle as a preservative (hesslein et al. 1991) to prevent bacterial growth while leaving the ph of the water sample unaltered. serum bottles were sealed with rubber septa and completely voided of air using a vacuum pump. a syringe of ambient air was then used to inject a 10 ml headspace into each serum bottle. triplicate samples of ambient air were taken so that the initial concentrations of co2 and ch4 in the headspace could be measured and subsequently deducted from sample concentrations. serum bottles prepared in this fashion have been stored for up to two months with no loss of vacuum (hamilton et al. 1994), although all bottles used herein were prepared less than two weeks before sampling. the method used to collect samples at channel sites was determined by the prevailing ice conditions. if the channel ice cover was still intact and sturdy enough to support the weight of a helicopter, samples were collected through an augered hole in the ice surface. a weighted, slow-filling sampler was continuously raised and lowered through the water column under the ice to collect an integrated water sample that was emptied into a 10 l bucket, from which all dic and gas samples were taken. after the channel ice had broken up to the point where it could no longer safely support the weight of a helicopter, the helicopter instead landed on pontoons on the channel surface in a stretch of open water. a 10 l bucket was used to collect surface water, from which gas samples were taken, while dic samples were taken directly from the channel by submerging a 1 l hdpe bottle well below the water surface. during the falling freshet, the mackenzie river was sampled by collecting surface water in a 20 l bucket lowered over the side of a commuter ferry, from which all dic and gas samples were taken. in each case, three gas samples were taken from a single water sample by submerging serum bottles below the water surface in the bucket and piercing each septum with a 16g needle. when water flow into the bottle ceased, the needle was removed and the bottle left submerged for one min to ensure that the septum had fully resealed. the serum bottles were gently swirled to dissolve all kcl and stored in dark, cool (4 °c) conditions during transport (less than eight hours) to the inuvik research centre in inuvik, northwest territories. our sampling method using a large bucket therefore yielded three pseudoreplicates from a single water sample, which allowed us to assess the replicability of our sample analysis. while using a large bucket to collect water samples allowed us to repeatedly sample the mackenzie river and delta channels under challenging field conditions during the freshet, the turbulence it created may have caused some gas to evade prior to sub-sampling. this is particularly likely to have happened when an integrated sample was emptied from the sampler into the bucket. as a result, the gas concentrations and fluxes presented herein are conservative low-end estimates of real-world conditions. laboratory analyses dic. water samples were filtered through millipore membrane filters (filter code gpwp, 0.2 µm pore size) and stored in acid-, ddiand sample-rinsed borosilicate vials. concentrations of dic and δ13c-dic were measured using a modified oi 1010 total organic carbon wet chemical oxidation analyser coupled to a thermo delta plus xp isotope ratio mass spectrometer following the methods of osburn & st.-jean (2007). samples were injected into the wet chemical oxidation analyser, acidified and sparged to drive all inorganic carbon out of solution as co2 gas, which was quantified as dic using a nondispersive infrared detector. co2 gas was then carried into the mass spectrometer in a stream of ultra-high purity he for measurement of δ13c. stable isotope values for dic are reported in per mille units (‰): where rsample is the ratio of 13c/12c in the sample and rstd is the ratio of 13c/12c in the co2 reference gas. values of δ 13c-dic were normalized to the vienna pee dee belemnite international scale using solutions of oxalic acid (–18.3‰) and l-glutamic acid (–26.2‰). dissolved gases. samples were warmed to room temperature and shaken for 20 min using a wrist-action shaker to equilibrate the gas and liquid phases. a gas-tight syringe was used to extract headspace gas for analysis on a varian 3800 gas chromatograph that used a thermal conductivity detector to measure co2 concentrations, and a flame-ionizing detector to measure ch4 concentrations. for each sample run, a four-point calibration curve was constructed using gas standards (48, 347, 912 and 5823 ppm for co2; 54, 359, 928 and 5946 ppm for ch4). headspace gas concentrations were adjusted to account for the ambient co2 and ch4 present in the original headspace, and corrected to give in situ concentrations (cw; µmol l-1) and partial pressures (pco2, pch4; µatm) using gas-specific constants corrected for salinity (resulting from the addition of kcl preservative) and water temperature (epa 2004; sander 2014). henry’s law constant was used for co2, following the methods of weiss (1974), while the bunsen solubility coefficient was used for ch4, following the methods of yamamoto et al. (1976). concentrations of each gas in equilibrium with the atmosphere (ca; µatm) were also determined using atmospheric levels of co2 and ch4. these were assumed to be 395.5 and 1.9 µatm, respectively, which were derived from the average atmospheric concentrations in dry air during the sampling period at the nearest global greenhouse gas reference network site in barrow, alaska (71.323°n, 156.611°w; noaa esrl global monitoring division 2016; dlugokencky et al. 2019). analytical constraints in early may, and the loss of one sample during shipping, prevented direct measurement of gas concentrations in a total of six samples. although ch4 concentrations could not be reconstructed, missing co2 concentrations were calculated using total alkalinity, dic concentrations and ph. alkalinity was determined using gran’s plot analysis of acid titration curves (gran 1952). the resulting data points (co2 concentrations and fluxes from all sites on 5 may and from the middle channel on 24 may) should be considered conservative estimates of actual gas concentrations because gas may have evaded from the water sample during storage. calculations of f-gas values of f-gas (µmol m-2 h-1) were calculated as: where kgas is a gas-specific transfer velocity (cm h-1), cw is the gas concentration in water (µmol l-1), ca is the gas concentration in equilibrium with the overlying atmosphere (µmol l-1) and 10 is a unit conversion factor. negative values of f-gas indicate a gas flux from the atmosphere into the water body (invasion), while positive values indicate a gas flux out of the water body to the atmosphere (evasion). gas fluxes expressed as moles of gas per unit area per hour were then converted to flux rates expressed as the mass of carbon per unit area per day (mg-c m-2 d-1). we were not able to directly measure kgas during our study. the floating chamber method (frankignoulle 1988) is frequently used in gas flux studies in aquatic systems to determine gas-specific transfer velocities (kgas) that are specific to the conditions of the study system. this method requires direct measurement of changes in gas concentrations over time in a closed headspace directly above the air–water interface. during our study, however, neither the conditions at the time of sampling (moving ice in delta channels), nor our method of accessing sampling sites (either by helicopter or commuter ferry), permitted repeated measurements of a closed headspace over time. we therefore used a range of co2-specific gas transfer velocities (kco2) for large rivers and estuaries that were published by raymond & cole (2001). this range of kco2 values (3–7 cm h-1) is likely lower than real-world values in the mackenzie delta channel network (see the discussion), so we propose that the flux values presented herein are conservative estimates. we have included further information on system conditions affecting gas transfer velocities, and other methods of estimating kgas for comparative purposes, in the supplementary material. gas transfer velocities for ch4 (kch4) were found using the high and low limits for kco2 (3 and 7 cm h-1) and the following equations: where sc-co2 and sc-ch4 are the temperature-dependent schmidt numbers calculated according to the methods of macintyre et al. (1995) and wanninkhof (1992), respectively. f-gas was calculated using daily gas concentration data from each site, and both the high and low limit for the applicable gas transfer velocity, yielding two flux estimates (high and low) for each gas. for co2, the flux equation was further modified to account for potential chemical enhancement of flux rates due to the rapid dissociation of h2co3 to (hco3+ h+) in the water column using the dimensionless enhancement factor α: chemical enhancement is greater at high ph, low wind speeds and low values of k600 (wanninkhof & knox 1996). the flux of co2 was calculated with no enhancement when cw > ca, but with enhancement when cw < ca. including chemical enhancement in co2 flux calculations generally increased the rate of invasion by less than 2%. calculations of ice-out fluxes across the air–water interface of the channel network the total flux of both co2 and ch4 from the mackenzie delta channel network during ice-out was estimated for the month of may 2010. each delta transect (inflow rivers, middle delta and outer delta) was first considered individually. for the inflow transect, f-gas values from the mackenzie and peel on each sampling day were weighted using river discharge. the resulting flow-weighted daily flux rates were then averaged for the rising freshet (1–19 may) and early flood recession periods (20–31 may), multiplied by the number of days in each period (19 and 12, respectively), and multiplied by the total channel surface area in the inflow transect (as determined by emmerton et al. [2007]). the fluxes for the rising freshet and early flood recession periods were then summed to give a total inflow transect flux for each gas during may 2010. the smaller number of samples that were taken in the middle and outer delta transects did not allow the rising freshet and early flood recession periods to be analysed separately. instead, for the middle and outer delta transects, instantaneous fluxes were averaged over all sampling days in may, multiplied by the number of days in the month (31), and then multiplied by the total channel surface area in each transect (as determined by emmerton et al. [2007]). as a final step, fluxes from each transect were summed to give a total delta-wide flux for each gas during the month of may 2010. using similar methods, fluxes were also estimated across the entire open-water season of 2010, which started on 25 april and continued to 25 october, the last ice-free day in the fall. to evaluate the effect of including data from the rising freshet period, all fluxes were recalculated with rising freshet data from the inflow transect excluded. data analysis significant differences in the average concentration of excess gas (cw–ca) were examined among all sites using a one-way anova on base-10 log transformed data, followed by a tukey hsd post-hoc test to account for the error accumulation associated with multiple tests. differences in the average f-gas generated by our high (7 cm h-1) versus our low (3 cm h-1) limits on the gas transfer velocity (kco2) were examined among sites using paired t-tests. we acknowledge that our approach, which grouped all data at a sampling site across all sampling dates, assumed that there was no temporal autocorrelation in our data sets. in all cases, data from the mackenzie river and the middle channel site in the middle delta transect were grouped together, both because of the small number of samples at the middle channel site and because the influence of the mackenzie river dominates any other influence (e.g., peel river, outflow from the delta floodplain) at the middle channel site (morley 2012). all statistical analyses were performed using jmp statistical software (version 13.1.0). results patterns in gas concentrations during the 2010 freshet values of pco2 in the mackenzie river (average ± sd 232 ± 80 µatm) were well below atmospheric equilibrium (395.5 µatm) during the rising freshet (fig. 3a, table 1a). as the freshet progressed, pco2 increased above atmospheric equilibrium shortly after peak water levels were reached and remained high throughout the falling freshet (average ± sd 581 ± 244 µatm). when plotted against discharge, pco2 showed an anti-clockwise hysteresis with higher partial pressures on the descending limb of the hydrograph compared to the ascending limb (fig. 4a), indicating that the river only acted as a source of co2 to the atmosphere during the later stages of the freshet. sites in the middle and outer delta declined from aboveto below-atmospheric equilibrium during the rising freshet, while in contrast, pco2 for the peel river remained well above equilibrium (average ± sd 1069 ± 402 µatm) throughout the sampling period (fig. 3a, table 1a). fig. 3  gas concentration data for the mackenzie river and delta channels during the 2010 freshet. (a) partial pressures (µatm) of co2 (top) and ch4 (bottom). in both graphs, the dashed vertical line indicates the day of peak discharge in the mackenzie river (19 may 2010), while the dashed horizontal lines indicate the atmospheric concentrations of each gas (co2 = 395.5 µatm, ch4 = 1.9 µatm). the red diamond in the pco2 graph denotes an anomalous data point (18 june 2010) that was excluded from all analyses. note that there are no ch4 data shown for the middle channel on 24 may 2010 because the sample was lost in transit. (b) the excess gas (concentration in water relative to the concentration in air) for co2 (top) and ch4 (bottom). note that the mackenzie river and middle channel sites were grouped together (mack+md). boxplots show medians and quartiles (boxes), averages (filled diamonds), 90% confidence intervals (whiskers) and ranges (hollow dots). in each graph, those sites accompanied by the same letter (shown below each boxplot) had mean values that were not significantly different from one another (p > 0.05) according to a one-way anova on base-10 log transformed data, followed by a tukey hsd post-hoc test. fig. 4  partial pressures (µatm) of (a) co2 and (b) ch4 versus discharge (q), as measured in 2010 at the mackenzie river sampling site immediately upstream of the mackenzie delta. both gases show hysteresis, but in opposite directions (anticlockwise for co2, clockwise for ch4). the red diamond in the co2 graph is an anomalous data point (18 june 2010) that was excluded from the trend analysis. table 1 partial pressures (µatm) and f-gas (mg-c m-2 d-1) of co2 and ch4 from (a) the 2010 ice-out and freshet in the mackenzie river and delta, and (b) prior studies of large river and floodplain systems. for (a) partial pressures are presented as averages (sd), and flux rates are presented as the low and high estimates of the average found using the limits on the gas transfer velocity proposed for large rivers and estuaries by raymond & cole (2001). for (b) partial pressures and fluxes may be presented as averages (sd), ranges (minimum–maximum) or in another fashion, depending on how results were reported in the source material. reference system pco2 (µatm) f-co2 (mg-c m-2 d-1) pch4 (µatm) f-ch4 (mg-c m-2 d-1) (a) this study mackenzie river (rising freshet) 232 (80) [–258 – (–112)] 170 (82) (3.6 – 8.5)   mackenzie river (falling freshet) 581 (244) (74 – 177) 81 (5) (1.2 – 2.8)   peel river 1069 (402) (373 – 871) 89 (10) (1.7 – 3.9)   middle delta (mackenzie delta) 475 (186) (51 – 119) 157 (44) (3.4 – 7.9)   outer delta (mackenzie delta) 441 (289) (27 – 65) 189 (92) (4.1 – 9.5) (b) prior studies       circumpolar river systems telang 1985 mackenzie river 4663 (3893)       vallières et al. 2008 mackenzie delta channels 694       tank et al. 2009 mackenzie delta lakes   (−600 – 1600)     cunada 2016 mackenzie delta lakes (ice-out) > 4000   50 – 8000 72 bussmann et al. 2017 lena river delta       (0.05 – 1.96) striegl et al. 2012 yukon river   2055   14.4 lauerwald et al. 2015 yukon river (582 – 705) (380 – 696)     kling et al. 1992 kuparuk river 812 (811) 143 (83) 236 4 semiletov 1999 kolyma river (716 – 1779)       denfeld et al. 2013 kolyma river 613 (315) 500 (700)     bastviken et al. 2011 global rivers > 66° n       7 lauerwald et al. 2015 large rivers > 50° n (888 – 1086) (251 – 364)     other large river systems at lower latitudes alt 1993 st. lawrence river 2322 (214)       cole & caraco 2001 hudson river 1062 (417) (192 – 444)     alt 1993 mississippi river 4593 (183)       pulliam 1993 ogeechee river floodplain   2518   271 butman & raymond 2011 temperate rivers, 25 – 50° n   6500     gan et al. 1983 yangtze river 1222 (264)       borges, darchambeau et al. 2015 sub-saharan rivers 6415 (2931 – 3950) 35 (86 – 118) alin et al. 2011 mekong river (703 – 1597) 1384 (1182)     borges et al. 2018 mekong delta (479 – 2664) 397 (187) < 3.5 1.1 (0.6) alin et al. 2011; borges, abril et al. 2015 amazon river (1600 – 6037) (530 – 3008)     richey et al. 2002 amazon river and floodplain   2274 (658)     dalmagro et al. 2018 pantanal (5973 – 14 292) 320 (2956 – 51 675) 20 stanley et al. 2016 worldwide     2165 (< 0.01 – 486) values of pch4 in the mackenzie river remained well above atmospheric equilibrium throughout the freshet, reaching a peak of 241 µatm shortly before peak flood (fig. 3a, table 1a). partial pressures then declined and were relatively constant (74–89 µatm) for the remainder of the falling freshet, indicating a strong net evasion from the mackenzie during the high-water period. values of pch4 displayed clockwise hysteresis, with higher concentrations on the ascending limb of the hydrograph as opposed to the descending limb, indicating that the river was a greater source of ch4 to the atmosphere during the early freshet (fig. 4b). at downstream delta sites pch4 values increased rapidly around the time of peak flood, while remaining relatively constant in the peel river throughout the freshet (average ± sd 89 ± 10 µatm; fig. 3a, table 1a). when delta sites were examined across all sampling dates, the peel river had a significantly greater excess of co2 relative to the atmosphere than any other site (p < 0.05), and was the only site to have consistently evasive fluxes across all dates (i.e., did not have a range that encompassed 0, or equilibrium with the atmosphere) (fig. 3b). for ch4, all sites had an excess relative to the atmosphere, although this excess was significantly greater in the outer delta (p < 0.05) (fig. 3b). values of pco2 and pch4 were significantly inversely related at the mackenzie sites (p < 0.05) and in the outer delta (p < 0.05), but not in the peel river (fig. 5). fig. 5  partial pressures of co2 (pco2, µatm) versus ch4 (pch4, µatm) measured at mackenzie delta channel sampling sites during the 2010 freshet. note that the mackenzie river and middle channel sites were grouped together (mack+md). significant linear regressions between pco2 and pch4 are shown as lines that match legend entries by colour (* indicates p < 0.05). inorganic carbon species as determinants of in situ gas concentrations all channel sites in the mackenzie delta were found to be dic-rich (fig. 6a). concentrations of dic exceeded 1000 µmol l-1 on all sampling occasions, with average values over the freshet sampling period ranging from a low of 1615 µmol l-1 in the outer delta to a high of 1775 µmol l-1 in the peel river. concentrations of dic were only significantly related to gas concentrations at the mackenzie-influenced sites, however (p < 0.01 for both pco2 and pch4; fig. 6a). values for δ13c-dic fell in a narrow range, with average values during the freshet ranging from –6.14 to -6.52‰ in the mackenzie sites and the peel, respectively (fig. 6b). the relationship between δ13c-dic and gas concentrations was not found to be significant at any site (fig. 6b). fig. 6  scatterplots of (a) dic (µmol l-1) and (b) δ13c-dic (expressed in per mille or ‰) versus pco2 (left) and pch4 (right). note that the mackenzie river and middle channel sites were grouped together (mack+md). significant linear regressions are shown as lines that match legend entries by colour (** indicates p < 0.01). instantaneous and delta-wide gas fluxes in the mackenzie river, values of f-co2 were below 0 mg-c m-2 d-1 throughout the rising freshet (fig. 7a). estimates of the average f-co2 during this period ranged from –258 mg-c m-2 d-1 to –112 mg-c m-2 d-1 (table 1a), indicating a net invasion of co2 from the atmosphere into the river leading up to the highest-discharge period of the year. following peak discharge on 19 may 2010, f-co2 values increased (fig. 7a) and there was a net evasion of co2 from the mackenzie river for the rest of the sampling period (low-high range in the estimated average f-co2 from 74 to 177 mg-c m-2 d-1; table 1a). sites in the mackenzie delta that are strongly influenced by the mackenzie river (middle channel, outer delta) also switched to net co2 invasion during the passage of peak discharge (fig. 7a), while, in contrast, the peel river remained a net emitter of co2 throughout the freshet (low-high range in the estimated average f-co2 from 373 to 871 mg-c m-2 d-1; table 1a). net evasion of ch4 was observed at all sites during the freshet, with f-ch4 showing a strongly increasing trend throughout the sampling period at the outer delta sites (fig. 7a). the average f-co2 value calculated across all sampling dates (f-co2) was greater in the peel river than at any other site, while the average f-ch4) value across all sampling dates was greatest in the outer delta (fig. 7b). we only found a significant difference between the high (kco2 = 7 cm h-1) and low (kco2 = 3 cm h-1) estimates of average f-co2 in the peel river; however, the high (kch4 = 6.90 cm h-1) and low (kch4 = 2.96 cm h-1) estimates of average f-ch4 were significantly different at all sites (fig. 7b). fig. 7  gas flux data for the mackenzie river and delta channels during the 2010 freshet. (a) average f-gas values (mg-c m-2 d-1) for both co2 (top) and ch4 (bottom), calculated as the average of our high and low estimates on each date. high and low estimates were derived using the upper and lower limits for the co2 gas transfer velocity (kco2) proposed by raymond & cole (2001). in all graphs, the dashed vertical line indicates the day of peak flood (19 may 2010), and the dashed horizontal line shown in the co2 graph denotes a flux of 0 mg-c m-2 d-1 (i.e., co2 equilibrium with the atmosphere). the red diamond in the pco2 graph denotes an anomalous data point (18 june 2010) that was excluded from all analyses. note that there are no ch4 data shown for the middle channel on 24 may 2010 because the sample was lost in transit. (b) f-gas values for co2 (top) and ch4 (bottom), calculated using daily gas concentration data and the lower (blue) and upper (red) limits on the gas-specific transfer velocity proposed by raymond & cole (2001). note that the mackenzie river and middle channel sites were considered together (mack+md). boxplots show medians and quartiles (boxes), averages (filled diamonds), 90% confidence intervals (whiskers) and ranges (hollow dots). paired t-tests were used to identify sites where the lower and upper limits on the gas transfer velocity produced significantly different average values of f-gas (* indicates p < 0.05, ** indicates p < 0.01, *** indicates p < 0.001). estimated gas fluxes from the entire mackenzie delta channel network are reported as high and low estimates that were calculated using gas concentration data and, respectively, the upper and lower limits on the gas transfer velocities that were proposed by raymond & cole (2001). for co2, the average instantaneous flux rate ranged (low to high) from 20.0 to 48.0 mg-c m-2 d-1 in the inflow transect, from 50.6 to 118.7 mg-c m-2 d-1 in the middle delta, and from 27.4 to 65.1 mg-c m-2 d-1 in the outer delta (table 2a). for ch4, flux rates ranged (low to high) from 2.6 to 6.1 mg-c m-2 d-1 in the inflow transect, 3.4 to 7.9 mg-c m-2 d-1 in the middle delta transect and 4.1 to 9.5 mg-c m-2 d-1 in the outer delta transect (table 2b). when extrapolated across the total surface area of mackenzie delta channels throughout the month of may 2010, the total co2 flux was between 2.1 and 4.8 gg-c, while the total ch4 flux was between 186 and 433 mg-c (table 2). excluding rising freshet data from delta-wide gas flux estimates had a greater effect on co2 fluxes than on ch4 fluxes (table 3). in the absence of rising freshet data, delta-wide co2 flux estimates were about 72% greater during the may 2010 freshet period, while ch4 flux estimates were about 7% less. when extrapolated over the entire 2010 open-water period, which lasted from 25 april to 25 october, excluding rising freshet data increased delta-wide co2 flux estimates by 9% but decreased ch4 flux estimates by only 2%. table 2 estimated fluxes of (a) co2 and (b) ch4 across the air–water interface of mackenzie delta channels during the may 2010 freshet and ice-out. values of f-gas for each delta transect were calculated using gas concentration data and the low and high limits on the gas transfer velocity that were proposed by raymond & cole (2001). values of f-gas were then extrapolated across the channel surface area in each transect to give transect-specific fluxes, which were summed to give total delta-wide fluxes from all channel surfaces. (a) co2 inflow middle delta outer delta total flux (gg-c) f-co2 (mg-c m-2 d-1) area (km2) flux (gg-c) f-co2 (mg-c m-2 d-1) area (km2) flux (gg-c) f-co2 (mg-c m-2 d-1) area (km2) flux (gg-c) low limit (kco2 = 3 cm h-1) 20.0 325.646 0.2 50.6 889.993 1.4 27.4 528.647 0.5 2.1 high limit (kco2 = 7 cm h-1) 48.0 325.646 0.5 118.7 889.993 3.3 65.1 528.647 1.1 4.8 (b) ch4 inflow middle delta outer delta total flux (mg-c) f-ch4 (mg-c m-2 d-1) area (km2) flux (mg-c) f-ch4 (mg-c m-2 d-1) area (km2) flux (mg-c) f-ch4 (mg-c m-2 d-1) area (km2) flux (mg-c) low limit (kch4 = 2.96 cm h-1) 2.6 325.646 26.3 3.4 889.993 93.0 4.1 528.647 66.5 186 high limit (kch4 = 6.90 cm h-1) 6.1 325.646 61.3 7.9 889.993 216.9 9.5 528.647 155.3 433   table 3 estimated delta-wide fluxes of (a) co2 (gg-c) and (b) ch4 (mg-c) across the air–water interface of the mackenzie delta channel network. estimates were calculated using the low and high limits on the gas transfer velocity that were proposed by raymond & cole (2001), and over both the month of may 2010 and the entire 2010 open water season (25 april–25 october 2010). the effect of including data from the rising freshet, which lasted from 25 april to 19 may 2010, was assessed by recalculating all flux estimates with rising freshet data from the inflow transect excluded. with rising freshet data rising freshet data excluded % difference (a) co2 (gg-c) may 2010 (31 days) low limit (kco2 = 3 cm h-1) 2.1 3.5 173% high limit (kco2 = 7 cm h-1) 4.8 8.3 172% 2010 open-water season, 25 april – 25 october 2010 (183 days) low limit (kco2 = 3 cm h-1) 4.4 4.8 109% high limit (kco2 = 7 cm h-1) 10.4 11.3 109% (b) ch4 (mg-c)       may 2010 (31 days) low limit (kch4 = 2.96 cm h-1) 186 172 93% high limit (kch4 = 6.90 cm h-1) 433 401 93% 2010 open-water season, 25 april – 25 october 2010 (183 days) low limit (kch4 = 2.96 cm h-1) 772 759 98% high limit (kch4 = 6.90 cm h-1) 1801 1771 98% discussion unexpected freshet co2 gradients in the mackenzie river and delta although we expected to observe co2 supersaturation in the mackenzie river during the freshet due to overwinter accumulation of dissolved gases under ice, we found that the mackenzie was a net absorber of co2 during the ice-out and rising freshet periods of 2010. most surprisingly, the lowest pco2 value (125 µatm) was observed on the day of peak flood (fig. 3a). our results countered prior observations in large seasonally flooded river systems, such as the amazon (richey et al. 2002; rasera et al. 2013; sawakuchi et al. 2017) and mekong (borges et al. 2018), which generally have the highest values of pco2 when water levels and discharge peak. in contrast to the mackenzie, pco2 in the peel river was consistently supersaturated throughout the rising freshet and peak discharge period (table 1a, fig. 3a). our observations in the peel more closely aligned with prior measurements in other north-flowing circumpolar rivers, such as the kolyma (semiletov 1999; denfeld et al. 2013) and the kuparuk (kling et al. 1992), which tend to have supersaturated pco2 levels that are nevertheless substantially lower than those in tropical or temperate rivers (table 1b). prior observations of co2 undersaturation in northern river systems have generally been restricted to small headwater streams, and to the summer low-water season. for example, in an extensive study of the yukon river basin, striegl et al. (2012) found that the average pco2 across all sampling sites was 1500 µatm, with most nearor below-equilibrium pco2 values measured in small headwater streams. compared to larger streams and the river mainstem, headwater streams receive a disproportionately large amount of meltwater from ice and snow cover relative to their total discharge volume (striegl et al. 2012), which dilutes concentrations of in situ co2. as another example, denfeld et al. (2013) observed near-equilibrium pco2 values in the kolyma river, which alternated between acting as a weak source and a weak sink of co2 (pco2 = 613 ± 315 µatm) during the summer open water period. the sampling period in denfeld et al. (2013) was well after the full passage of the freshet in the kolyma, when the dominant basin flow paths were through deeper soil layers rather than over the basin surface (denfeld et al. 2013) where large amounts of dissolved gases are generated by aerobic and anaerobic decomposition. unlike the dic-rich mackenzie system (flow-weighted concentrations greater than 20 mg l-1; tank et al. 2012; gareis & lesack 2017), the kolyma is dic-poor (flow-weighted concentration of 7.7 mg l-1; tank et al. 2012), which, along with primary production in basin surface waters, may have contributed to the periodic observations of pco2 undersaturation in the kolyma (denfeld et al. 2013). large subarctic and circumpolar rivers have not been hypothesized to be consistently undersaturated in co2 at any time of the year because of these few, specific instances that generate undersaturated pco2 conditions in this class of river. values of pco2 at downstream sites in the mackenzie delta also declined below atmospheric levels as the rising freshet progressed downstream, with the lowest pco2 values observed on 16 may in the middle delta and on 19 may in the outer delta (fig. 3a). again, these observations contradicted our expectation that overwinter accumulation of co2 under ice would generate supersaturated conditions during the freshet. our results also contradicted prior observations in other floodplain systems around the world (table 1b), which are generally strong direct sources of co2 to the atmosphere (pulliam 1993; richey et al. 2002; marani & alvalá 2007; abril et al. 2014; borges, darchambeau et al. 2015) as well as sources of dissolved co2 to downstream regions because of high levels of the gas that are carried in floodwater (borges, darchambeau et al. 2015). during a prior study, late summer measurements of pco2 in an outer channel of the mackenzie delta averaged 694 µatm over a four-hour sampling period (vallières et al. 2008), which aligned with our observed pco2 values in the mackenzie river during the falling freshet (average = 581 µatm), implying that co2 levels in the mackenzie may be consistently above atmospheric following the passage of peak flood. overall, however, the mackenzie delta was only a weak emitter of co2 during the 2010 ice-out period. it is unlikely that co2 undersaturation in the mackenzie river and delta during the freshet results from dilution by snowmelt, as was seen in the small headwater streams of the yukon basin (striegl et al. 2012). in the much larger mackenzie river, the movement of snowmelt over the basin surface and through shallow sub-surface flow paths adds high levels of visibly chromophoric dom. absorption coefficients at 350 nm (a350), a proxy for dom concentrations, reach an annual maximum of 14.6 m-1 during the rising freshet (gareis 2018), as do concentrations of dissolved organic carbon (gareis & lesack 2017). these sources of dissolved organic material fuel co2-producing bacterial respiration following exposure to sunlight in surface waters (cory et al. 2013). it is also unlikely that co2 undersaturation in the mackenzie river and delta results from in situ primary production, as was seen in the kolyma during the summer low flow season (denfeld et al. 2013). the mackenzie river is extremely cold (average temperature < 1 °c; gareis unpubl. data) and turbid (average total suspended solids concentration of 301 mg l-1; gareis & lesack 2017) during the ice-out and freshet. together, these conditions strongly limit rates of water-column primary production by both rooted and planktonic autotrophs during the rising freshet in the mackenzie river, resulting in an average rising freshet chlorophyll concentration of 1.5 µg l-1 over the four years of this study (gareis unpubl. data). we propose that one plausible explanation for the observed co2 undersaturation in the mackenzie river and delta during the ice-out and freshet is a draw-down of co2 by the carbonate buffering system in the river. this would decrease the co2 concentration in water relative to that in air, thereby shifting the gradient across the air–water interface to favour co2 invasion while maintaining the high dic concentrations observed in the river (fig. 6a). the mackenzie river contains high concentrations of carbonate particles (brunskill 1986; millot et al. 2003) that are generated by weathering of dolomite, calcite and other carbonate rocks in the high-relief mackenzie and rocky mountains in the western mackenzie basin and the flatter interior platform in the middle of the basin (millot et al. 2003; beaulieu, goddéris et al. 2012). furthermore, throughout the ice-out and freshet δ13c-dic fell in a narrow range (–5 to –8 ‰; fig. 6b) that is characteristic of a geogenic source of inorganic carbon (campeau et al. 2017) such as carbonate dissolution (schulte et al. 2011), rather than the more isotopically light values (e.g., –26 to –28 ‰) that are generated when dic is produced by the breakdown of organic matter (coplen et al. 2002). carbonate buffering resulting from chemical weathering of carbonate minerals in the river basin has been observed to decrease rates of co2 evasion in high-alkalinity systems (stets et al. 2017) such as the mackenzie (tank et al. 2016). chemical weathering consumed an estimated 9.2 × 1010 mol co2 a-1 in the mackenzie river basin when atmospheric co2 concentrations were 355 µatm, with consumption projected to increase as atmospheric co2 increases in future (beaulieu, goddéris et al. 2012). prior work on the beaufort shelf has found high concentrations of carbonate (4–5% by weight) in nearshore sediments, with concentrations decreasing as offshore distance from the mackenzie delta increases, supporting a riverine source of carbonate to the shelf (pelletier 1975). although these factors indicate that the carbonate buffering system is the most likely driver of co2 undersaturation in the mackenzie during the rising freshet, further sampling during the ice-out and freshet periods is needed to definitively resolve this. the mackenzie river and delta are strong emitters of ch4 during the freshet contrary to our co2 results, our ch4 results were consistent with our expectation that the mackenzie river and delta would remain a net source throughout the freshet and that concentrations and fluxes of ch4 would be greatest around the time of peak water levels. instantaneous rates of ch4 flux in the mackenzie delta inflow rivers are comparable to, or somewhat lower than, many previously published values from other systems, with f-ch4 in the mackenzie ranging from 1.2 to 8.5 mg-c m-2 d-1 and in the peel from 1.7 to 3.9 mg-c m-2 d-1. for comparison, the average f-ch4 in global circumpolar rivers is estimated to be 7 mg-c m-2 d-1 (bastviken et al. 2011), while f-ch4 was measured as 4 mg-c m-2 d-1 in the kuparuk river (kling et al. 1992) and 14.4 mg-c m-2 d-1 in the yukon (striegl et al. 2012) (table 1). our results therefore align with the results of prior studies of ch4 in northern rivers (bastviken et al. 2011) as well as rivers and streams worldwide (stanley et al. 2016), which have shown that ch4 supersaturation and evasion to the atmosphere are the norms in lotic systems. a large net excess of ch4 gas (fig. 3b) and strong evasive fluxes to the atmosphere (fig. 7) were observed at all downstream sites in the mackenzie delta. values of pch4 in the outer delta transect were supersaturated (average 189 µatm) and comparable to reported pch4 values in the kuparuk river in alaska (236 µatm; kling et al. 1992), as well those for river floodplains at lower latitudes (see examples in table 1b). our results were in agreement with two prior studies that were conducted for other large circumpolar river deltas. in a 10-year study in the yukon river system, all sampled locations (240+) were found to be supersaturated with ch4 (striegl et al. 2012), while in the lena, sampling sites in the river mainstem and delta channels were between 900% and 3000% supersaturated with ch4 (bussmann 2013). our ch4 results are therefore comparable to previously published ch4 concentrations and fluxes in other large circumpolar rivers and deltas, and align with our hypothesis that the greatest gas fluxes would be observed at downstream sites in the delta. the increasing rates of ch4 evasion we saw in the middle and outer delta as the freshet progressed downstream may have been subsidized by dissolved ch4 from floodplain lakes on the mackenzie delta. at ice-out, delta lakes are supersaturated with ch4 due to overwinter accumulation under ice, with concentrations of up to 1050 mg-c m2 (cunada 2016). as water levels reach their peak, an average of 25.8 km3 of floodwater spreads out over the mackenzie delta floodplain, where it mixes with up to 5.4 km3 of ch4-supersaturated lake water (emmerton et al. 2007). this modified mixture of floodwater and lake water drains back into delta channels, where it has the potential to reinforce the ch4 peak seen in the mackenzie river and drive the large excess of ch4 in water relative to air that was observed at downstream sites. factors affecting gas flux estimates to our knowledge, this study presents the first direct measurements of co2 and ch4 concentrations during the ice-out and rising freshet periods in a large north-flowing circumpolar river delta. although gas concentrations in water and the overlying atmosphere are straightforward to measure, the calculation of accurate gas transfer velocities is far more difficult, and inaccuracies in k600 values can result in large errors in instantaneous and system-wide fluxes. there are therefore two factors that may have produced errors in our k600 values, and subsequently our gas flux estimates, which must be considered when interpreting the results of this study. the first is that we used a method of calculating k600 that was derived from the literature, rather than from repeated measurements of gas concentrations in a closed system at the air–water interface (the “floating chamber” method, as described by frankignoulle [1988]). although applying generalized gas transfer velocities from the literature can produce significant errors in estimates of flux rates (e.g., as discussed by wallin et al. 2011), we were unable to use the floating chamber method to calculate system-specific flux rates because of the sampling conditions during the ice-out period when our study took place. our objective was to quantify co2 and ch4 concentrations and fluxes during ice-out and the high-discharge period of the rising freshet leading up to peak flood, when ice in delta channels has fractured and started to move downstream with increasing speed and force driven by rapidly increasing discharge. the only way to access sampling sites during this time is by means of a helicopter, which requires either landing on ice sheets or sampling off the helicopter pontoons in mid-channel openings in the ice cover. this constrained our sampling to only direct measurements of gas concentrations in channels, and we therefore inferred the direction of gas flow throughout the ice-out and high-discharge freshet period using concentration gradients across the air–water interface. although our sampling method accurately resolved the direction of the gas flux, the gas exchange coefficients we used to calculate fluxes undoubtedly influenced our results. the gas exchange coefficient (k600) is an expression of the turbulent energy at the air–water interface, and both its value and its variability within a system are important determinants of gas flux rates (raymond & cole 2001; alin et al. 2011; striegl et al. 2012; raymond et al. 2013; sawakuchi et al. 2017). in shallower streams and headwaters, k600 is controlled by bottom friction and is generally a function of water current velocity and channel slope (alin et al. 2011; raymond et al. 2012). at larger scales, such as in estuaries and river mainstems greater than 100 m in width, wind exerts a stronger influence on k600 values (raymond & cole 2001; alin et al. 2011). additionally, there are other factors that may also influence gas transfer velocities in the mackenzie river and delta during breakup, including increased roughness of the air–water interface due to ice rubble and debris in the channel, ice jams in delta channels that increase the lateral spread of floodwater onto the floodplain, and wind and water currents that are directionally opposed to one another (zappa et al. 2007; beaulieu, shuster et al. 2012). in the absence of direct measurements of k600 across the air–water interface in mackenzie delta channels and, after consideration of potential extreme gas coefficient values in this system (see the supplementary material), we have opted to present estimates of instantaneous gas fluxes that were generated using the limits proposed by raymond & cole (2001). however, given that all river and delta channels that were sampled during this study were considerably wider than 100 m (ranging from approximately 300 m to over 4 km in width), and that wind speeds can be high in the area (particularly along the beaufort coast), the fluxes presented herein are likely conservative estimates and we acknowledge that actual fluxes of both co2 and ch4 are likely much greater. the second factor that must be considered is that our sampling programme was restricted to delta channels and did not include samples from wetted floodplain surfaces that were covered by some amount of river water during the freshet. floodplains are substantial sources of co2 and ch4 evasion in other systems (pulliam 1993; richey et al. 2002; marani & alvalá 2007; abril et al. 2014; borges, darchambeau et al. 2015; dalmagro et al. 2018) due to leaching of gases from submerged soils and vegetation, and both aerobic and anaerobic decomposition of organic matter. although we were unable to sample directly over wetted floodplain surfaces, our sampling scheme included downstream locations in the outer delta, and data from these sites suggest that there may be significant contributions of ch4 that are generated on the delta floodplain. also, during high-water periods, the more than 45 000 floodplain lakes on the mackenzie delta become hydrologically reconnected to delta channels. prior work in these floodplain lakes (tank et al. 2009; cunada 2016) suggests that large amounts of dissolved gases generated under ice over winter may be mobilized into distributary channels when lakes are flooded during the freshet. accurate quantification of these potentially significant fluxes of carbon-based greenhouse gases over seasonally flooded portions of the mackenzie delta floodplain will require further study. delta-wide estimates of freshet and open water gas fluxes we estimated the total ice-out gas fluxes from the mackenzie delta by combining our low and high estimates for the mackenzie delta channels (2.1 to 4.8 gg-c as co2, 186 and 433 mg-c as ch4; table 2) with previously published ice-out fluxes for the more than 45 000 floodplain lakes in the mackenzie delta. for co2, our channel flux estimate is comparable in magnitude to the ice-out flux estimate for mackenzie delta floodplain lakes (10.6 gg-c as co2; cunada 2016), but for ch4 our channel flux estimate is an order of magnitude lower than that for mackenzie delta floodplain lakes (8.41 gg-c as ch4; cunada 2016). together, our fluxes along with those of cunada (2016) suggest that between 12.7 and 15.4 gg-c evades from the mackenzie delta as co2 during ice out, and between 8.6 and 8.8 gg-c evades as ch4. these are the first estimates of the fluxes of co2 and ch4 from a large circumpolar river delta during ice-out of which we are aware. delta-wide flux estimates of co2 were more greatly affected by the exclusion of rising freshet data than were ch4 flux estimates (table 3), reflecting the switch from net invasion to evasion of co2 with the passage of peak flood in the mackenzie river and delta. although the difference between the co2 flux estimates with and without rising freshet data was large during the may 2010 ice-out period (ca. 72%), the short duration of the rising freshet (24 days) relative to the rest of the open water period (153 days) means that there was only a moderate difference (ca. 9%) between the two total open water season flux estimates. these results are based on data from only a single ice-out and breakup period, however, and may therefore either underor overestimate the effect of temporary co2 undersaturation on total delta-wide fluxes. sampling during future ice-out and breakup periods is needed to resolve the magnitude of the effect of co2 drawdown on fluxes in this system. conclusions while fluxes of co2 and ch4 from large rivers in the tropics and temperate zones are relatively well known, they are poorly characterized and may be underestimated in large river systems at high latitudes (e.g., bastviken et al. 2011; raymond et al. 2013). fluxes of two globally-important greenhouse gases across the air–water interface were monitored in the channel network of the mackenzie delta during the ice-out and freshet periods of 2010, which corresponds with the ice-out period for the more than 45 000 floodplain lakes in this exceptionally lake-rich system. this study is the first of which we are aware which quantified co2 and ch4 during the historically under-sampled periods of ice-out, rising freshet and peak water levels in one of the world’s major circumpolar rivers and its delta. we conservatively estimated that total fluxes from the channel network for the month of may 2010 were 2.1–4.8 gg-c as co2, and 186–433 mg-c as ch4. while the peel river was a strong net emitter of co2 throughout the freshet, it contributes a relatively small proportion of the total water flow into the delta (ca. 5%), with most inflowing water (ca. 95%) coming from the mackenzie river. the mackenzie was a net absorber of co2 during the rising freshet (f-co2 of -112 to -258 mg-c m-2 d-1), as were downstream sites in the delta, with all sites switching to co2 evasion around the time of peak flood and water levels. overall, the mackenzie delta was a weak emitter of co2 during the 2010 ice-out and freshet, which was unexpected and contradicts observations in other large river systems where high evasive fluxes of co2 are observed during high-flow periods. all sites were strong emitters of ch4 throughout the freshet and ice-out, however, with upstream–downstream concentration gradients that suggest that the delta floodplain is a source of this gas. current estimates of gas evasion from global rivers are 1.8 pg-c a-1 as co2 (raymond et al. 2013) and 20.1 tg-c a-1 as ch4 (stanley et al. 2016). although mackenzie delta ice-out fluxes represent only a very small percentage of the total annual global flux for either gas, our results nevertheless provide critical information that can be used to refine estimates of gas fluxes from high-latitude lotic systems during the relatively under-studied ice-out and freshet periods. however, our results also point towards a need for repeated sampling in future years to determine whether the co2 undersaturation observed during the 2010 freshet is a yearly occurrence in the mackenzie, and to determine the mechanism responsible for this seasonal draw-down of co2 in one of the world’s largest circumpolar river delta systems. acknowledgements the research reported in this article was conducted under nwt scientific research licence no. 14 687. logistical support was provided by the aurora research institute and the inuvik office of the water survey of canada branch of environment canada. analytical support was provided by the laboratories of v.l. st. louis (university of alberta) and c.l. osburn (north carolina state university). the authors thank c.l. cunada for valuable help with methods, l. duma for assistance in the field and laboratory and r.w. macdonald for suggestions and comments that greatly improved the manuscript. three anonymous reviewers also provided suggestions and comments that greatly improved the quality of this article. references abril g., martinez j.m., artigas l.f., moreira-turcq p., benedetti m.f., vidal l., meziane t., kim j.h., bernardes m.c., savoye n., deborde j., souza e.l., alberic p., de souza m.f.l. & roland f. 2014. amazon river carbon dioxide outgassing fueled by wetlands. nature 505, 395–398, doi: 10.1038/nature12797. alin s.r., rasera m.f.f.l., salimon c.i., richey j.e., holtgrieve g.w., krusche a.v. & snidvongs a. 2011. physical controls on carbon dioxide transfer velocity and flux in low-gradient river systems and implications for regional carbon budgets. journal of geophysical research—biogeosciences 116, g01009, doi: 10.1029/2010jg001398. alt d.f. 1993. state water data records: hydrologic records of the united states water years 1990, 1991 and 1992. united states geological survey open file report 93-626. cd-rom. doi: 10.3133/ofr93626. us geological survey. amon r.m.w., rinehart a.j., duan s., louchouarn p., prokushkin a., guggenberger g., bauch d., stedmon c., raymond p.a., holmes r.m, mcclelland j.w., peterson b.j., walker s.a. & zhulidov a.v. 2012. dissolved organic matter sources in large arctic rivers. geochimica et cosmochimica acta 94, 217–237, doi: 10.1016/j.gca.2012.07.015. bastviken d., tranvik l.j., downing j.a., crill p.m. & enrich-prast a. 2011. freshwater methane emissions offset the continental carbon sink. science 331, 50, doi: 10.1126/science.1196808. beaulieu e., goddéris y., donnadieu y., labat d. & roelandt c. 2012. high sensitivity of the continental-weathering carbon dioxide sink to future climate change. nature climate change 2, 346–349, doi: 10.1038/nclimate1419. beaulieu j.j., shuster w.d. & rebholz j.a. 2012. controls on gas transfer velocities in a large river. journal of geophysical research—biogeosciences 117, g02007, doi: 10.1029/2011jg001794. beltaos s. 2012. mackenzie delta flow during spring breakup: uncertainties and potential improvements. canadian journal of civil engineering 39, 579–588, doi: 10.1139/i2012-033. blackburn j., she y., hicks f. & nafziger j. 2015. ice effects on flow distributions in the mackenzie delta. proceedings of the 18th workshop on the hydraulics of ice covered rivers. quebec city: committee on river ice processes and the environment. borges a.v., abril g. & bouillon s. 2018. carbon dynamics and co2 and ch4 outgassing in the mekong delta. biogeosciences 15, 1093–1114, doi: 10.5194/bg-15-1093-2018. borges a.v., abril g., darchambeau f., teodoru c.r., deborde j., vidal l.o., lambert t. & bouillon s. 2015. divergent biophysical controls of aquatic co2 and ch4 in the world’s two largest rivers. scientific reports 5, article no. 15614, doi: 10.1038/srep15614. borges a.v., darchambeau f., teodoru c.r., marwick t.r., tamooh f., geeraert n., omengo f.o., guerin f., lambert t., morana c., okuku k. & bouillon s. 2015. globally significant greenhouse-gas emissions from african inland waters. nature geoscience 8, 637–642, doi: 10.1038/ngeo2486. brunskill g.j. 1986. environmental features of the mackenzie system. in b.r. davies & k.f. walker (eds.): the ecology of river systems. pp. 435–471. dordrecht: dr. w. junk publishers. bussmann i. 2013. distribution of methane in the lena delta and buor-khaya bay, russia. biogeosciences 10, 4641–4652, doi: 10.5194/bg-10-4641-2013. bussmann, i., hackbusch s., schaal p. & wichels a. 2017. methane distribution and oxidation around the lena delta in summer 2013. biogeosciences 14, 4985–5002, doi: 10.5194/bg-14-4985-2017. butman d. & raymond p.a. 2011. significant efflux of carbon dioxide from streams and rivers in the united states. nature geoscience 4, 839–842, doi: 10.1038/ngeo1294. campeau a. & del giorgio p.a. 2014. patterns in ch4 and co2 concentrations across boreal rivers: major drivers and implications for fluvial greenhouse gas emissions under climate change scenarios. global change biology 20, 1075–1088, doi: 10.1111/gcb.12479. campeau a., wallin m.b., giesler r., löfgren s., mörth c.-m., schiff s., venkiteswaran j.j. & bishop k. 2017. multiple sources and sinks of dissolved inorganic carbon across swedish streams, refocusing the lens of stable c isotopes. scientific reports 7, article no. 9158, doi: 10.1038/s41598-017-09049-9. cole j.j. & caraco n.f. 2001. carbon in catchments: connecting terrestrial carbon losses with aquatic metabolism. freshwater and marine research 52, 101–110, doi: 10.1071/mf00084. coplen t.b., hopple j.a., böhlke j.k., peiser h.s., rieder s.e., krouse h.r., rosman k.j.r., ding t., vocke r.d. jr. révész k.m., lamberty a., taylor p. & de bièvre p. 2002. compilation of minimum and maximum isotope ratios of selected elements in naturally occurring terrestrial materials and reagents. water-resources investigations report 01-4222. reston, va: us department of the interior and us geological survey. cory r.m., crump b.c., dobkowski j.a. & kling g.w. 2013. surface exposure to sunlight stimulates co2 release from permafrost soil carbon in the arctic. proceedings of the national academy of sciences of the united states of america 110, 3429–3434, doi: 10.1073/pnas.1214104110. crawford j.t., striegl r.g., wickland k.p., dornblaser m.m. & stanley e.h. 2013. emissions of carbon dioxide and methane from a headwater stream network of interior alaska. journal of geophysical research—biogeosciences 118, 482–494, doi: 10.1002/jgrg.20034. cunada c.l. 2016. seasonal methane dynamics in lakes of the mackenzie river delta, western canadian arctic. msc thesis, simon fraser university. dalmagro h.j., lathuilliere m.j., hawthorne i., morais d.d., pinto o.b., couto e.g. & johnson m.s. 2018. carbon biogeochemistry of a flooded pantanal forest over three annual flood cycles. biogeochemistry 139, 1–18, doi: 10.1007/s10533-018-0450-1. denfeld b.a., frey k.e., sobczak w.v., mann p.j. & holmes r.m. 2013. summer co2 evasion from streams and rivers in the kolyma river basin, north-east siberia. polar research 32, article no. 19704, doi: 10.3402/polar.v32i0.19704. denfeld b.a., wallin m.b., sahlée e., sobek s., kokic j., chmiel h.e. & weyhenmeyer g.a. 2015. temporal and spatial carbon dioxide concentration patterns in a small boreal lake in relation to ice-cover dynamics. boreal environment research 20, 679–692. dlugokencky e.j., crotwell a.m. & mund j.w. 2019. atmospheric methane dry air mole fractions from quasi-continuous measurements at barrow, alaska and mauna loa, hawaii, 1986-2018. version 2019-03-04. accessed on the internet at ftp://aftp.cmdl.noaa.gov/data/trace_gases/ch4/in-situ/surface/ on 20 january 2020. emmerton c.a., lesack l.f.w. & marsh p. 2007. lake abundance, potential water storage, and habitat distribution in the mackenzie river delta, western canadian arctic. water resources research 43, w05419, doi: 10.1029/2006wr005139. epa (environmental protection agency) 2004. standard operating procedure. sample preparation and calculations for dissolved gas analysis in water samples using a gc headspace equilibration technique. rsksop-175. 2004. revision 2. accessed on the internet at https://archive.epa.gov/region1/info/testmethods/web/pdf/rsksop175v2.pdf on 16 january 2020. frankignoulle m. 1988. field measurements of air–sea co2 exchange. limnology and oceanography 33, 313–322, doi: 10.4319/lo.1988.33.3.0313. gan w.b., chen h.m. & hart y.f. 1983. carbon transport by the yangtze (at nanjing) and huanghe (at jinan) rivers, people’s republic of china. in e.t. degens et al. (eds.): transport of carbon and minerals in major world rivers. part 2. pp. 459–470. hamburg: scientific committee on problems of the environment, united nations environment programme. gareis j.a.l. 2018. arctic deltas as biogeochemical hotspots affecting the delivery of nutrients and dissolved organic matter to the arctic ocean. phd thesis, simon fraser university. gareis j.a.l. & lesack l.f.w. 2017. fluxes of particulates and nutrients during hydrologically defined seasonal periods in an ice-affected great arctic river, the mackenzie. water resources research 53, 6109–6132, doi: 10.1002/2017wr020623. gran g. 1952. determination of the equivalence point in potentiometric titrations, part ii. analyst 77, 661–671, doi: 10.1039/an9527700661. hamilton j.d., kelly c.a., rudd j.w.m., hesslein r.h. & roulet n.t. 1994. flux to the atmosphere of ch4 and co2 from wetland ponds on the hudson bay lowlands (hbls). journal of geophysical research—atmospheres 99, 1495–1510, doi: 10.1029/93jd03020. hesslein r.h., rudd j.w.m., kelly c., ramlal p. & hallard k.a. 1991. carbon dioxide pressure in surface waters of canadian lakes. in s.c. wilhelms & j.s. gulliver (eds.): air–water mahss transfer: selected papers from the second international symposium on gas transfer at water surfaces. pp 413–431. new york, ny: american society of civil engineers. hydat 2019. water survey of canada real time hydrometric data. accessed on the internet https://wateroffice.ec.gc.ca/search/historical_e.html on 16 january 2020. jammet m., dengel s., kettner e., parmentier f.j.w., wik m., crill p. & friborg t. 2017. year-round ch4 and co2 flux dynamics in two contrasting freshwater ecosystems of the subarctic. biogeosciences 14, 5189–5216, doi: 10.5194/bg-14-5189-2017. kling g.w., kipphut g.w. & miller m.c. 1992. the flux of co2 and ch4 from lakes and rivers in arctic alaska. hydrobiologia 240, 23–36, doi: 10.1007/bf00013449. lauerwald r., laruelle g.g., hartmann j., ciais p. & regnier p.a. 2015. spatial patterns in co2 evasion from the global river network. global biogeochemical cycles 29, 534–554, doi: 10.1002/2014gb004941. lesack l.f.w. & marsh p. 2010. river‐to‐lake connectivities, water renewal, and aquatic habitat diversity in the mackenzie river delta. water resources research 46, w12504, doi: 10.1029/2010wr009607. lesack l.f.w., marsh p., hicks f.e. & forbes d.l. 2013. timing, duration, and magnitude of peak annual water levels during ice breakup in the mackenzie delta and the role of river discharge. water resources research 49, 8234–8249, doi: 10.1002/2012wr013198. macintyre s., wanninkhof r. & chanton j.p. 1995. trace gas exchange across the air–water interface in freshwater and coastal marine environments. in p.a. matson & r.c. harriss (eds.): biogenic trace gases: measuring emissions from soil and water. pp. 52–97. oxford: john wiley and sons ltd. marani l. & alvalá p.c. 2007. methane emissions from lakes and floodplains in pantanal, brazil. atmospheric environment 41, 1627–1633, doi: 10.1016/j.atmosenv.2006.10.046. michmerhuizen c.m., striegl r.g. & mcdonald m.e. 1996. potential methane emission from north-temperate lakes following ice melt. limnology and oceanography 41, 985–991, doi: 10.4319/lo.1996.41.5.0985. millot r., gaillardet j., dupré b. & allègre c.j. 2003. northern latitude chemical weathering rates: clues from the mackenzie river basin, canada. geochimica et cosmochimica acta 67, 1305–1329, doi: 10.1016/s0016-7037(02)01207-3. morley j.k.a. 2012. observations of flow distributions and river breakup in the mackenzie delta, nwt. msc thesis, university of alberta. noaa esrl global monitoring division 2016, updated annually. atmospheric carbon dioxide dry air mole fractions from quasi-continuous measurements at barrow, alaska. version 2017-8. compiled by k.w. thoning et al. doi: 10.7298/v5rr1w6b. boulder, co: national oceanic and atmospheric administration, earth system research laboratory, global monitoring division. osburn c.l. & st-jean g. 2007. the use of wet chemical oxidation with high-amplification isotope mass spectrometry (wco-irms) to measure stable isotope values of dissolved organic carbon in seawater. limnology and oceanography—methods 5, 296–308, doi: 10.4319/lom.2007.5.296. pelletier b.r. 1975. sediment dispersal in the southern beaufort sea (beaufort sea technical report 25a). victoria, canada: beaufort sea project. phelps a.r., peterson k.m. & jeffries m.o. 1998. methane efflux from high-latitude lakes during spring ice melt. journal of geophysical research—atmospheres 103, 29029–29036, doi: 10.1029/98jd00044. pulliam w.m. 1993. carbon dioxide and methane exports from a southeastern floodplain swamp. ecological monographs 63, 29–53, doi: 10.2307/2937122. rasera m.f.f.l., krusche a.v., richey j.e., ballester m.v.r. & victória r.l. 2013. spatial and temporal variability of pco2 and co2 efflux in seven amazonian rivers. biogeochemistry 116, 241–259, doi: 10.1007/s10533-013-9854-0. raymond p.a., caraco n.f. & cole j.j. 1997. carbon dioxide concentration and atmospheric flux in the hudson river. estuaries 20, 381–390, doi: 10.2307/1352351. raymond p.a. & cole j.j. 2001. gas exchange in rivers and estuaries: choosing a gas transfer velocity. estuaries 24, 312–317, doi: 10.2307/1352954. raymond p.a., hartmann j., lauerwald r., sobek s., mcdonald c., hoover m., butman d., striegl r., mayorga e., humborg c., kortelainen p., dürr h., meybeck m., ciais p. & guth p. 2013. global carbon dioxide emissions from inland waters. nature 503, 355–359, doi: 10.1038/nature12760. raymond p.a., zappa c.j., butman d., bott t.l., potter j., mulholland p., laursen a.e., mcdowell w.h. & newbold d. 2012. scaling the gas transfer velocity and hydraulic geometry in streams and small rivers. limnology and oceanography: fluids and environments 2, 41–53, doi: 10.1215/21573689-1597669. richey j.e., melack j.m., aufdenkampe a.k., ballester v.m. & hess l.l. 2002. outgassing from amazonian rivers and wetlands as a large tropical source of atmospheric co2. nature 416, 617–620, doi: 10.1038/416617a. sander r. 2014. compilation of henry’s law constants, version 3.99. atmospheric chemistry and physics discussions 14, 29615–30521, doi: 10.5194/acpd-14-29615-2014. sawakuchi h.o., neu v., ward n.d., barros m.dl.c, valerio a.m., gagne-maynard w., cunha a.c., less d.f.s., diniz j.e.m., brito d.c., krusche a.v. & richey j.e. 2017. carbon dioxide emissions along the lower amazon river. frontiers in marine science 4, unsp 76, doi: 10.3389/fmars.2017.00076. schulte p., van geldern r., freitag h., karim a., négrel p., petelet-giraud e., probst a., probst j.-l., telmer k., veizer j. & barth j.a.c. 2011. applications of stable water and carbon isotopes in watershed research: weathering, carbon cycling, and water balances. earth-science reviews 109, 20–31, doi: 10.1016/j.earscirev.2011.07.003. semiletov i.p. 1999. aquatic sources and sinks of co2 and ch4 in the polar regions. journal of the atmospheric sciences 56, 286–306, doi: 10.1175/1520-0469(1999)056<0286:asasoc>​2.0.co;2. spencer r.g.m., mann p.j., dittmar t., eglinton t.i., mcintyre c., holmes r.m., zimov n. & stubbins a. 2015. detecting the signature of permafrost thaw in arctic rivers. geophysical research letters 42, 2830–2835, doi: 10.1002/2015gl063498. stanley e.h., casson n.j., christel s.t., crawford j.t., loken l.c. & oliver s.k. 2016. the ecology of methane in streams and rivers: patterns, controls, and global significance. ecological monographs 86, 146–171, doi: 10.1890/15-1027. stets e.g.d., butman d., mcdonald c.p., stackpoole s.m., degrandpre m.d. & striegl r.g. 2017. carbonate buffering and metabolic controls on carbon dioxide in rivers. global biogeochemical cycles 31, 663–677, doi: 10.1002/2016gb005578. striegl r.g., dornblaser m.m., mcdonald c.p., rover j.r. & stets e.g. 2012. carbon dioxide and methane emissions from the yukon river system. global biogeochemical cycles 26, gb0e05, doi: 10.1029/2012gb004306. tank s.e., lesack l.f.w. & hesslein r.h. 2009. northern delta lakes as summertime co2 absorbers within the arctic landscape. ecosystems 12, 144–157, doi: 10.1007/s10021-008-9213-5. tank s.e., raymond p.a., striegl r.g., mcclelland j.w., holmes r.m., fiske g.j. & peterson b.j. 2012. a land-to-ocean perspective on the magnitude, source and implication of dic flux from major arctic rivers to the arctic ocean. global biogeochemical cycles 26, gb4018, doi: 10.1029/2011gb004192. tank s.e., striegl r.g., mcclelland j.w. & kokelj s.v. 2016. multi-decadal increases in dissolved organic carbon and alkalinity flux from the mackenzie drainage basin to the arctic ocean. environmental research letters 11, 054015, doi: 10.1088/1748-9326/11/5/054015. telang s.a. 1985. transport of carbon and minerals in the mackenzie river. in e.t. degens et al. (eds.): transport of carbon and minerals in major world rivers. part 3. pp. 337–344. hamburg: scientific committee on problems of the environment, united nations environment programme. vallières c., retamal l., ramlal p., osburn c.l. & vincent w.f. 2008. bacterial production and microbial food web structure in a large arctic river and the coastal arctic ocean. journal of marine systems 74, 756–773, doi: 10.1016/j.jmarsys.2007.12.002. vonk j.e., mann p.j., davydov s., davydova a., spencer r.g.m., schade j., sobczak w.v., zimov n., zimov s., bulygina e., eglinton t.i. & holmes r.m. 2013. high biolability of ancient permafrost carbon upon thaw. geophysical research letters 40, 2689–2693, doi: 10.1002/grl.50348. wallin m., buffam i., öquist m., laudon h. & bishop k. 2010. temporal and spatial variability of dissolved inorganic carbon in a boreal stream network, concentration and downstream evasion. journal of geophysical research—biogeosciences 115, go2014, doi: 10.1029/2900jg001100. wallin m., öquist m., buffam i., billett m., nisell j. & bishop k. 2011. spatiotemporal variability of the gas transfer coefficient (kco2) in boreal streams: implications for large scale estimates of co2 evasion. global biogeochemical cycles 25, gb3025, doi: 10.1029/2010gb003975. wanninkhof r. 1992. relationship between wind speed and gas exchange over the ocean. journal of geophysical research—oceans 97, 7373–7382, doi: 10.1029/92jc00188. wanninkhof r. & knox m. 1996. chemical enhancement of co2 exchange in natural waters. limnology and oceanography 41, 689–697, doi: 10.4319/lo.1996.41.4.0689. weiss r.f. 1974. carbon dioxide in water and seawater: the solubility of a non-ideal gas. marine chemistry 2, 203–215, doi: 10.1016/0304-4203(74)90015-2. yamamoto s., alcauskas j.b. & crozier t.e. 1976. solubility of methane in distilled water and seawater. journal of chemical and engineering data 21, 78–80, doi: 10.1021/je60068a029. zappa c.j., mcgillis w.r., raymond p.a., edson j.b., hintsa e.j., zemmelink h.j., dacey j.w.h. & ho d.t. 2007. environmental turbulent mixing controls on air–water gas exchange in marine and aquatic systems. geophysical research letters 34, l10601, doi: 10.1029/2006gl028790. minimally invasive physiological correlates of social behaviour in belugas (delphinapterus leucas) under human care research article minimally invasive physiological correlates of social behaviour in belugas (delphinapterus leucas) under human care justin t. richard,1,2 rachael levine,1,2 tracy a. romano2 & becky l. sartini1 1department of fisheries, animal and veterinary sciences, university of rhode island, kingston, ri, usa; 2mystic aquarium, mystic, ct, usa abstract simultaneous observations of reproductive physiology and behaviour were conducted on a group of two male and two female belugas under professionally managed care for one year to explore potential mating strategies. weekly blow sampling for progesterone in females was used to define the breeding season by detecting three oestrous cycles in one female. twice weekly blow sampling for testosterone and twice monthly testes measurements via ultrasonography were used to detect reproductive seasonality in both males. female–male association frequency varied longitudinally, with 70% of all interactions occurring during the 16-week breeding season. male–male associations did not vary seasonally. male display behaviours towards the female occurred 14.8 times more frequently during the breeding season (0.164 ± 0.188 behaviours/min) than outside of the breeding season (0.011 ± 0.042 behaviours/min). the cycling female responded variably to male display behaviours by altering swim speed or body orientation towards the male. although this small sample size limits broad conclusions, the frequent display behaviours, low copulation rate and lack of serious male–male aggression are consistent with predictions for pre-copulatory female mate choice developed from the current knowledge of beluga reproductive physiology. these observations, which are not feasible for wild belugas, provide important management considerations because reduced opportunities for mate choice could limit the reproductive rate, especially in small populations. keywords reproduction; cetacean; mating strategies; blow; steroid hormones; aquarium abbreviations %b/bo: percent analyte bound to the antibody divided by the maximum possible binding to the antibody cl: corpus luteum coa: coefficient of association cv: coefficient of variation gp: genital presents sd: standard deviation ttv: total testicular volume   citation: polar research 2021, 40, 5504, http://dx.doi.org/10.33265/polar.v40.5504 copyright: polar research 2021. © 2021 j.t. richard et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 26 july 2021 competing interests and funding: the authors report no conflict of interest. this material is based upon work supported by the national science foundation graduate research fellowship awarded to jtr under grant no. 1244657. funding for this project was provided by the sea research foundation, inc. d/b/a mystic aquarium and through the university of rhode island’s enhancement of graduate research award programme. correspondence to: justin t. richard, 9 east alumni ave., university of rhode island, kingston, ri 02881, usa. e-mail: jt_richard@uri.edu this article is part of the special cluster beluga whales (delphinapterus leucas): knowledge from the wild, human care and tek, which has been funded by mystic aquarium, caff and the norwegian ministry of climate and environment. introduction the inherent link between reproductive behaviour and population dynamics necessitates an understanding of mating strategies to aid population management. as some mating strategies may be more resilient to perturbation than others, understanding the strategies employed by a species is important information when faced with rapid environmental change (quader 2005) or at low population densities (møller & legendre 2001). beluga (delphinapterus leucas) behaviour is influenced by sea-ice loss (o’corry-crowe et al. 2016), and for several stocks of belugas with small population sizes, the lack of recovery (wade et al. 2012) has not been adequately explained. therefore, understanding beluga mating strategies is critical for the successful conservation and management of this species, especially among small populations under anthropogenic pressures. belugas breed in the late winter or early spring, when most populations are inaccessible to human observers (burns & seaman 1988). in summer and fall, when belugas use more readily observable estuarine habitats in much of their range, they are often sexually segregated (michaud 2005). beluga mating strategies have been inferred primarily using morphological characteristics and population demographics to be polygynous or polygynandrous (o’corry-crowe et al. 1997; kelley et al. 2014). however, direct observations during the breeding season are unavailable to confirm these inferences. similarly, male–male relationships are considered important, perhaps for cooperation related to mating (o’corry-crowe et al. 2020), but direct observations are unavailable during the breeding season. when compared with other odontocetes, both preand post-copulatory selections are presumed to be relatively weak in belugas because of the lack of obvious male weaponry, undocumented behavioural displays for demonstrating male quality, relatively small degree of sexual size dimorphism and reduced investment in testes size (dines et al. 2015). integrating the available information on beluga reproductive anatomy and physiology could help to elucidate potential mating strategies. belugas have relatively low circulating testosterone concentrations (høier & heide-jørgensen 1994; robeck, monfort et al. 2005), small testes with reduced seasonal variation (richard, schmitt et al. 2017) and small ejaculate volumes (o’brien et al. 2008) compared to other odontocetes, for example, bottlenose dolphin (tursiops truncatus [schroeder & keller 1989; robeck, steinman et al. 2005; orbach et al. 2019]). the female beluga reproductive tract is less complex (fewer vaginal folds and shorter cumulative length of vaginal folds) than several odontocete species known to engage in sperm competition, in which these folds may allow for sperm selection or limit penile penetration (orbach et al. 2017). in aquaria, most beluga conceptions occur after testes begin to regress and testosterone concentrations begin to fall (robeck, steinman et al. 2005; richard, schmitt et al. 2017), in contrast to convention in vertebrates, including other odontocetes (wells 1984; wingfield et al. 1990; wu et al. 2010). taken together, these observations suggest a reduced role for sperm competition or male contest competition relative to other species of cetaceans. these findings could all be related to the recent discovery that belugas are facultative-induced ovulators (steinman et al. 2012). when compared to mammals with spontaneous ovulation, mammals with an induced mode of ovulation often display different reproductive behaviour because male–male post-copulatory competition is reduced. with induced ovulation, the ability of an individual male to monopolise paternity is generally increased, with the first male copulating with the female most likely to sire the offspring (lacey et al. 1997; soulsbury 2010). reduced male–male post-copulatory competition among species with induced ovulation is associated with smaller testes sizes and lower sperm concentrations per ejaculate when compared to spontaneously ovulating species (iossa et al. 2008; soulsbury & iossa 2010). with weak post-copulatory competition, females are expected to employ pre-copulatory mate selection. males would be expected to have variation in mating behaviours or other traits that could facilitate mate selection, and females would be expected to behave variably towards individual males, depending on the female’s reproductive state (orbach et al. 2015). therefore, to describe the mating strategies of a species most accurately, it is necessary to determine the reproductive condition of an individual at the time that reproductive behaviour is observed (e.g., muraco & kucjaz 2015). gonad function, measured through testes size, spermatogenic activity or follicular development, is an indicator of an individual’s reproductive condition and is often used to assess maturity and reproductive condition in adult odontocetes (neimanis et al. 2000; muraco & kucjaz 2015). reproductive steroid hormone measurements can be used to detect changes in gonad function, and therefore reproductive condition. therefore, studies that correlate steroid hormone concentrations and behaviour in wild animals are common across taxa, including several species of marine mammals (bartsh et al. 1992; burgess et al. 2012). however, sample matrices typically used to assess steroid hormone concentrations in cetaceans are either invasive (blood or blubber) or difficult to collect from free-swimming animals (urine or faeces). as a result, paired studies of reproductive behaviour and endocrinology in cetaceans are rare, even in aquaria, but yield important insights on the reproductive biology of a species (wells 1984; robeck et al. 1993; wu et al. 2010; muraco & kucjaz 2015). the physiological validation of blow (exhale) sampling for reproductive steroid hormone analysis in belugas (richard, robeck et al. 2017) facilitates repetitive sampling in real time and, thus, improves the feasibility of paired studies of beluga reproductive behaviour and endocrinology. this is especially true in aquaria, where underwater visibility and year-round access have allowed descriptive studies of reproductive behaviour (glabicky et al. 2010; hill et al. 2015; hill et al. 2018). however, observations of beluga reproductive behaviour have not yet been evaluated in the context of reproductive physiology, preventing discrimination of courtship behaviour from socio-sexual behaviour, which is common among odontocetes (mann 2006). whilst a study of belugas in an aquarium cannot be used to infer the mating system or specific reproductive strategies of all wild belugas, the more intensive data collection that is possible in this setting can provide valuable information that can be used to inform studies of wild belugas. in this study, minimally invasive methods were used to assess the relationship between reproductive physiology and behaviour of a group of aquarium belugas. based on our understanding of beluga physiology and wild beluga behaviour, female–male interactions were expected to be seasonal, and courtship behaviour was expected to occur most frequently when females were most receptive (the follicular phase of the oestrous cycle), which is most likely to occur after testosterone concentrations and testes size decline. male–male interactions were not expected to vary in frequency seasonally and were unlikely to be characterised by intense aggression. following predictions based on ovulation mode and reproductive anatomy in this species, a low copulation rate and opportunities for females to employ pre-copulatory mate choice were expected to occur. methods this study was conducted on four belugas (two females: f1 and f2; two males: m1 and m2) housed at mystic aquarium (mystic, ct) in a 2.8 million litre outdoor exhibit chilled to temperatures <16 °c. most of the exhibit is visible from underwater through large acrylic windows. behavioural observations and physiological measurements were performed for one year (52 consecutive weeks, henceforth numbered consecutively from 1 to 52) from 25 august 2013 to 21 august 2014. f2 was only available for the first 21 weeks of the study (table 1). this project was approved by the institutional animal care and use committees of mystic aquarium (project no. 12001) and the university of rhode island (project no. an12-02-016). table 1 study animals and samples. individuala ageb lengthc (cm) massc (kg) reproductive status no. of blow samples no. of blood samples no. of ultrasound exams f1 32 335 659 nulliparous 51 14 – f2 32 335 727 nulliparous 14 – – m1 27 399 945 proven sire 96 – 23 m2 11 390 723 no offspring sired 104 – 15 amale (m) and female (f). bage of the animal at the beginning of the study period. cmeasured once during the study period. physiological assessments of reproductive condition blow (exhale) samples were collected twice per week from the males and once per week from the females with the voluntary cooperation of the whale and analysed as described by richard, robeck et al. (2017). blow samples were collected in the morning hours between 09:00 and 11:30 and stored at –80 °c until analysis. blood sampling utilising trained behaviour was attempted once or twice per month with f1 as a part of routine veterinary monitoring. blood samples were collected into sodium heparinised vacutainer tubes from the ventral fluke vein. one millilitre of serum or sodium heparin plasma was obtained through centrifugation (2000 × g for 10 min at 10 °c) and stored at –80 °c until analysis. male samples were assayed for testosterone, and female samples were assayed for progesterone using enzyme immunoassays (cayman chemical, ann arbor, mi; item nos. 582701 and 582601) previously validated for use with beluga blow and blood samples (richard, robeck et al. 2017). all samples were assayed in duplicate, and the means were used in calculations. individual samples with a %b/bo between 20 and 80% and a cv below 20% were accepted. if sufficient volume was available, samples with cv >20% were re-assayed. when available, multiple samples collected within the same week were averaged to obtain weekly testosterone values. two standard controls were run in each assay (testosterone: 100 and 25 pg/ml, n = 12 assays; progesterone: 200 and 50 pg/ml, n = 14 assays). inter-assay variation was calculated by determining the cv for the two standard controls on each plate. intra-assay variation was calculated by averaging the cv for all of the samples with 20–80% binding on each plate. testosterone intra-assay variation was 7.7%; inter-assay variation was 5.7% for the 100 pg/ml control and 10.8% for the 25 pg/ml control. progesterone intra-assay variation was 11.7%; inter-assay variation was 5.8% for the 200 pg/ml control and 15.5% for the 50 pg/ml control. the average lower limit of detection (80% b/bo) was 10.9 pg/ml for testosterone and 30.5 pg/ml for progesterone. all biological samples assayed exceeded the lower limit of detection. some of the hormone measurements in blow samples have been presented previously (richard, robeck et al. 2017) and so are only reported here to contextualise behavioural observations. the occurrence of ovulation in f1 was inferred through progesterone measurements in blow and blood, using known oestrous cycle stage lengths in belugas reported by steinman et al. (2012); ultrasonographic data were unavailable in this study. ovulation leads to an increase in progesterone concentrations in beluga blow (richard, robeck et al. 2017). specifically for f1, the presence of a cl (confirmed via ultrasonography) was associated with an increase in blow progesterone that lasted approximately 20 days, from a baseline of 248.5 ± 62.5 pg/ml to 326.5 ± 33 pg/ml (mean ± sd; richard, robeck et al. 2017). high progesterone would be indicative of the luteal phase, which lasts 29–32 days in non-conceptive cycles (steinman et al. 2012). to minimise the chance of a false positive, ovulation was inferred to have occurred if two consecutive weekly samples exceed 326.5 pg/ml, the mean progesterone concentration during f1’s luteal phase monitored by richard, robeck et al. (2017). the follicular phase, which lasts 14–27 days (steinman et al. 2012), was conservatively presumed to occur in the week that ovulation was inferred to have occurred on the basis of an elevated progesterone measurement, as well as the two weeks preceding the week of ovulation. the follicular phase could overlap with the luteal phase of a previous non-conceptive cycle, as reported by steinman et al. (2012). inferred ovulations must be separated by at least 30 days, given the inter-oestrous interval of 33–34 days (steinman et al. 2012). ttv was determined using ultrasonography performed with the voluntary cooperation of the whale as described by richard, schmitt et al. (2017). exams were conducted twice per month by a single operator using a convex 3.5 mhz probe (ge logiq book with 3c-rs transducer, ge medical systems, china). behavioural observations an ethogram was developed using published descriptions of beluga behaviour (dipaola et al. 2007), as well as pilot observations of the study group performed in the breeding season (february–april) of the previous year (table 2). behaviour names were later refined to be consistent with publications available after the start of the study (hill et al. 2015; muraco & kucjaz 2015). a social interaction was defined as occurring when two or more whales are performing any of the social behaviours listed in the ethogram. of particular interest was the ‘genital present’ (fig. 1), which is similar to the pelvic thrust described by glabicky et al. (2010) and a combination of the horizontal ‘s’ posture and pelvic thrust behaviours described by hill et al. (2015). the definition used in this study removes any orientation restrictions on the occurrence of the behaviour, identifies the necessary presence of a recipient, separates this behaviour from copulation, accounts for the cessation of active swimming and reduces the implication that the behaviour is forcible. one whale length (ca. 4 m) was used as a distance frame of reference for several behaviours. the recipient of a behaviour in a social interaction with more than two whales was determined by the direction of the actor’s rostrum during a behavioural event. table 2 ethogram of social behaviours of interest. behaviour definition states  milling two or more whales actively swim, drift passively or lie still with no discernible pattern or in variable directions within 4 m of each other; may be associated with social events.  group swim two or more whales swim in the same direction at approximately the same velocity for at least 30 seconds; all whales are within 2 m of at least one other whale in the group; bodies can be aligned or staggered (one whale swims ahead of the other), but one whale may not be completely behind another; body orientation of individuals may vary. events  approach a whale alters swim direction or speed to initiate interaction with another whale(s), whilst the other whale(s) does not alter swim speed or direction; resulting position is less than 4 m from recipient whale; interaction is initiated.  separate a whale alters swim direction or speed to terminate interaction with another whale(s), whilst the other whale(s) does not alter swim direction or speed; resulting position is at least 4 m from previously interacting whale(s), terminating the interaction.  open mouth a whale opens mouth wide enough so that the tongue is (or would be) visible.  mouthing a whale makes contact with another whale with an open mouth.  melon shake a whale vigorously shakes head in dorsal/ventral plane, causing the melon to shake. mouth may be opened or closed.  erection any part of the penis is visible during any social interaction; it may occur simultaneously with any other social behaviour in this ethogram.  head nod a whale moves the head in a dorsal/ventral plane at least two times in succession without shaking the melon. mouth may be opened or closed.  flutter an atypical swimming motion in which the flukes are moved with greater tailbeat frequency at smaller amplitudes for at least three successive tailbeats, resulting in the shaking of the abdominal fat pads.  genital present whale stops active forward progress by terminating fluke beating and drifts in the direction of another whale whilst arching their caudal peduncle, so that the genital region is pushed closer to the recipient whale; caudal end of the caudal peduncle is correspondingly angled dorsally; rostrum is often directed towards the recipient whale for some portion of the presentation causing the body to assume an ‘s’ shape; flukes and flippers may be held at various angles to control the drift towards the recipient whale; it may result in contact of the genital region with the recipient. fig. 1 a sequential view of a genital present from a male (bottom of frame) towards a female (centre of frame). note the ventral orientation of the female relative to the male in (a) and the lateral orientation relative to the male by (c), in which the female’s ventral surface was rolled away from the male. the ‘s’ shape is clear in (d). observation protocol. four hours of observations were conducted per week: two hours in the morning between 07:00 and 10:00 and two hours in the afternoon between 15:00 and 18:00, for a total of 208 hr of observation completed in 211 observation sessions lasting 30–90 min each. continuous observations of the social group were conducted using a tripod-mounted digital video camera at the underwater viewing area. an event sampling rule was used in which the videographer focused filming on any social interaction that occurred during the filming period, regardless of participants, resulting in a continuous record of all social interactions visible from underwater viewing. if social interactions exceeding 1 min in duration occurred in one of the satellite pools that lack underwater viewing, the observer moved and recording was conducted from an above-water vantage point. observations were only conducted outside of training sessions. behavioural data were grouped by week (1–52). quantifying behaviour. the video material was first analysed for behavioural states by one of two observers. the animals engaging in the interaction were identified, as was the duration of the interaction to the nearest 5 seconds (minimum 5 seconds), and the animal that initiated (‘approach’) and terminated (‘separate’) the interaction. approaches and separations may not have been identified for interactions that started or ended prior to or after the observation session or out of view of the camera. the total number of interactions, the average duration of interactions and the total amount of time interacting were calculated for each social grouping and each behavioural state. weekly coas were calculated using the simple coa described by cairns & schwager (1987). in the next stage of analysis, behavioural event frequency was quantified using cowlog software (hänninen & pastell 2009) and continuous recording (martin & bateson 2007) by one of three observers. for each event, the actor, behaviour and recipient were recorded. behavioural event coding was not possible for interactions that occurred in the satellite pools that lacked underwater viewing, although the occurrence, duration and participants of the interactions in these pools were recorded. weekly behavioural event frequencies per minute of observation are reported as mean ± sd. genital presents. every occurrence of a genital present between a male and female was reviewed by a single observer (jtr) to describe the behaviour in greater detail and to determine the recipient’s response to the genital present display. the behavioural state and social grouping at the time of the genital present were recorded. the general area of the recipient’s body the actor directed the display towards (right lateral, left lateral, ventral or dorsal surface), the relative body position of the actor during the display (horizontal, head angled towards bottom or head angled towards surface) and the position of the whales in the water column (completely submerged or any part of the body at the surface) were also recorded. a ‘receptivity score’ was developed for the recipient and assigned to each occurrence of a male towards female genital present (table 3), with higher scores indicating increased receptivity. the body position of belugas during copulation has not been formally described, although intromission attempts are described as ventral to ventral (hill et al. 2015). therefore, receptivity was assumed to be characterised by matching swim speeds, presenting the ventral surface towards the actor and allowing physical contact to occur. table 3 ‘receptivity score’ scheme used to assign receptivity to genital presents. each occurrence received one score from each of the three categories (swim speed, orientation and contact), and the total receptivity score for each genital present is the sum of these three component scores. response score swim speed  recipient alters swim speed to increase distance from genital present 0  recipient continues to make forward progress during genital present (swim speed unchanged) 1  recipient stops active swimming and drifts during genital present 2 orientation  recipient rolls ventral surface away from the genital present 0  recipient remains stable along long axis so that genital present ends closer to dorsal surface than ventral surface 1  recipient rolls ventral surface towards the genital present or remains stable along long axis so that genital present ends closer to ventral surface than dorsal surface 2 contact  contact does not occur 0  contact occurs on recipient’s lateral or dorsal surfaces 1  contact occurs on recipient’s ventral surface 2 inter-observer reliability. inter-observer reliability for the coding of behavioural events was assessed by having all three observers code the same 10 hours of video, containing 133 min of social interaction (9% of all interactions). the identity of the participants in an interaction had 100% agreement between all three observers. for each behavioural event, a pairwise kappa statistic was determined, using observer 1 (jtr) as the reference observer. all behaviours had ‘excellent’ agreement (κ > 0.75) with observer 1 except mouthing for one observer pairing, which had ‘good’ agreement (κ = 0.63; kaufman & rosenthal 2009). inter-observer reliability for the coding of behavioural states was assessed by having both observers code the same 12 hours of video selected from 10 different months, containing 203 min of social interaction (14% of all interactions). the occurrence of interactions had 98.5% agreement between the two observers. the identifications of the behavioural states for these interactions had ‘excellent’ agreement (κ > 0.75; kaufman & rosenthal 2009). data analysis because of the small sample size and repeated sampling, statistical tests were not performed. descriptive statistics (mean ± sd) were used to describe variation in female–male association or specific behaviours with f1’s reproductive state. f2 was not in the social group during the time period when belugas are typically reproductively active, had no evidence of ovarian activity during the weeks she was observed, was only involved in 7% of all social interactions and did not receive any genital present behaviours. therefore, any descriptions of courtship behaviour will be in reference to f1. ‘breeding season’ is defined as the period of time lasting from the week containing the start of f1’s first inferred follicular phase through the week containing the start of the last luteal phase as determined via progesterone measurements in blow. f1’s receptivity towards genital presents performed by m1 and m2 was compared by calculating cohen’s d to estimate the effect size. box plots created in r (r core team 2020) show the interquartile range (box), the median (bold line) and the maximum (q3) or minimum value ≤1.5 times the interquartile range (whiskers). results progesterone assays once weekly once blow samples were available for f1 (table 4). for f2, blow sample volumes were commonly too small to assay, so that only 13/21 weeks were sampled. progesterone data are presented in table 4. elevated progesterone was not observed in any blow samples collected from f2. a total of 12 f1 blow samples exceeded the elevated progesterone concentration of 326.5 pg/ml (weeks 12, 20, 35–36, 38–39, 42 and 44–48). none of the blood samples collected from f1 during the study had progesterone concentrations indicative of luteal activity, although there was a 65-day gap in sampling between march and may. three periods met the requirements for inferring ovulation: weeks 35–36 (20 april–3 may), weeks 38–39 (11 may–24 may) and weeks 44–48 (22 june–26 july). using blood progesterone values to rule out active luteal phases and accounting for the 7–10-day gaps between sampling, corresponding follicular phases were inferred to span weeks 31–33 (23 march–12 april), 35–37 (20 april–10 may) and 43–45 (15 june–5 july). ‘breeding season’ will be defined as weeks 31–46. none of the inferred ovulations resulted in a detectable pregnancy. table 4 progesterone concentrations (pg/ml) from blood and blow for female belugas f1 and f2. id sample type no. of observations mean ± sd range f1 blow 52 291.1 ± 90.8 156.5–763.8 f2 blow 13 250.9 ± 49.8 143.76–312.1 f1 blood 14 473.7 ± 111.1 293.1–710.2 male physiological assessments two blow samples per week were available for all weeks for m1 except weeks 3, 25, 36, 39, 42, 42, 50 and 51, when only a single sample was available for assay. two samples per week were available for all weeks for m2 except weeks 35, 39 and 42. m1’s testosterone (107.0 ± 39.9 pg/ml) peaked during week 26 (207.7 pg/ml) and remained elevated above the mean from week 15 to week 36, with the exception of two weeks. m2’s blow testosterone concentration (97.0 ± 44.4 pg/ml) peaked in week 29 (277.1 pg/ml) and remained elevated above the mean from week 26 to week 39, with the exception of one week. m1’s ttv (993.3 ± 129.0 cm3) peaked in week 24 (1306.4 cm3) and remained, with the exception of one measurement, elevated above the mean from week 18 to 38. m2’s ttv (294.5 ± 32.7 cm3) never exceeded 366.0 cm3, beginning with the first available measurement in week 23. behavioural observations social interactions were observed in 197 of the 211 observation sessions and comprised 12% (1437 min in 2396 separate interactions) of the total time observed. a total of 45.2 min of interactions (3.1% of total interaction time) occurred in pools that lacked underwater viewing, and therefore lacked behavioural event data. interactions with f1 were comprised mostly of group swim interactions (by duration), whilst m1–m2 interactions were primarily milling interactions (table 5). female–male group swims often lasted several minutes, with maximum observed durations of 32 (m1) and 50 (m2) minutes. the approaching whale was identified for 2124 of the interactions (89%). the separating whale was identified for 2086 of the interactions (87%). of all male–f1 interactions, males initiated 94% and terminated 27%. of the male–male interactions, m2 initiated 80% and terminated 42%. table 5 amount of time in minutes spent interacting by group and behavioural state for male (m1 and m2) and female (f1) belugas. social group duration of interactions (min) milling group swim proportion of total duration duration per interaction proportion of total duration duration per interaction m1–f1 74.1 0.57 0.32 ± 0.42 0.43 1.60 ± 1.70 m2–f1 605.5 0.18 0.24 ± 0.39 0.82 4.36 ± 7.92 m1–m2–f1 175.2 0.12 0.27 ± 0.19 0.88 3.10 ± 5.34 m1–m2 485.3 0.90 0.33 ± 0.46 0.10 1.27 ± 0.80 variation in behaviour with f1’s breeding season interactions involving males and females occurred in every week of the year, and in 74% of the observation sessions. however, coa varied widely throughout the year, with 70% of all male–f1 interaction (597 min) occurring during the 16-week breeding season (30% of weeks; fig. 2). female–male coa was 0.107 ± 0.144 during f1’s inferred follicular phases and was 0.218 ± 0.174 during other weeks of the breeding season. f1 initiated more interactions (7.1% vs. 2.7%) and terminated fewer interactions (63.3% vs. 80.2%) during the breeding season than during other times of the year. there was less seasonal variability in interactions that only involved males; 35% of all male–male interaction (170 min) occurred during the breeding season. fig. 2 box plots of (a) weekly female–male coas between the males and female f1 and (b) the weekly rates per minute of male display behaviours (genital present, melon shake, head nod and flutter) towards f1 relative to f1’s breeding season. open circles indicate weeks during f1’s inferred follicular phases. the frequency of behaviours performed during interactions in relation to f1’s breeding season is presented in table 6. all male towards f1 behaviours were more frequent during the breeding season except mouthing, which was rarely observed. male display behaviours (genital presents, melon shakes, head nods and flutters) occurred 14.8 times more frequently during the breeding season (0.164 ± 0.188 behaviours/min) than outside of the breeding season (0.011 ± 0.042 behaviours/min; fig. 2). copulation was not observed. erections were rarely seen during male–female interactions (two from m1 and one from m2). both erections observed from m1 occurred with a genital present towards f1 during breeding season (weeks 33 and 35). the frequencies of male–male behaviours were similar in and out of breeding season except for genital presents (breeding season: 0.027 ± 0.071 and non-breeding season: 0.011 ± 0.026). table 6 variation in behaviour for male (m1 and m2) and female (f1) belugas relative to f1’s reproductive condition, during the breeding season (weeks 31–46) compared to outside of the breeding season. behaviour breeding season (mean ± sd) outside breeding season (mean ± sd) female–male coa 0.16 ± 0.17 0.03 ± 0.06 male-only coa 0.044 ± 0.035 0.036 ± 0.023 proportion of m–f1 interactions: group swim 0.61 ± 0.42 0.26 ± 0.32 duration of m–f1 interactions (seconds) 103.72 ± 314.78 31.12 ± 76.66 duration of m–m interactions (seconds) 25.8 ± 35.22 20.75 ± 30.87 behaviours directed to f1 breeding season frequency per minute observed (mean ± sd) outside breeding season frequency per minute observed (mean ± sd)  genital present 0.064 ± 0.085 0.004 ± 0.016  open mouth 0.149 ± 0.169 0.024 ± 0.033  melon shake 0.074 ± 0.097 0.005 ± 0.015  mouthing 0.0003 ± 0.001 0.001 ± 0.002  head nod 0.020 ± 0.024 0.002 ± 0.008  flutter 0.006 ± 0.007 0.001 ± 0.004 behaviours performed by f1  genital present 0.016 ± 0.032 0  open mouth 0.065 ± 0.09 0.003 ± 0.004  melon shake 0.019 ± 0.036 0  mouthing 0 0  head nod 0.008 ± 0.016 0  flutter 0 0 behaviours performed between m1 and m2  genital present 0.027 ± 0.071 0.011 ± 0.026  open mouth 0.096 ± 0.061 0.086 ± 0.058  melon shake 0.004 ± 0.007 0.004 ± 0.008  mouthing 0.028 ± 0.024 0.029 ± 0.038 male-towards-female genital presents occurred in 27 different observation sessions (13% of sessions). these 27 sessions also contained a majority of the occurrences of group swim (83%), open mouth (61%), melon shake (87%), head nod (79%) and flutter (74%). only 2 of those 27 sessions contained genital presents from both males towards f1. genital presents occurred during group swim 98% of the time. m1 performed 70% of his genital presents to f1 during her inferred follicular phases, compared to 37% of m2’s genital presents towards f1 (fig. 3). neither male was observed performing a genital present towards f1 during her third inferred follicular phase in weeks 43–45. m1 was not observed to perform a genital present towards f1 between 26 april and 30 july, whilst m2 performed 75% of his genital presents towards f1 during that period. no male towards male genital presents were observed in sessions when a male towards female genital present was also observed. all of f1’s genital presents were performed towards m2 in sessions where m2 also displayed a genital present towards f1. fig. 3 variation in the frequency of gp performed by the males (m1 and m2) towards the female f1 per minute of observation in relation to testosterone concentrations in blow and f1’s breeding season (shaded area) and inferred follicular phases (indicated along the x axis with grey bars). f1’s breeding season, and therefore much of the female–male behaviour observed, occurred after testosterone concentrations in blow started to decline for both males and testes size started to decline in m1 (fig. 3). mean individual female–male coas and display behaviour frequencies towards f1 were highest for both males whilst testosterone was declining from the peak measurement (fig. 4). m2 associated with f1 (781 min) more often than m1 (249 min) and performed more behavioural events towards f1 (1193) than m1 (324). f1’s head nods (100%), melon shakes (99%) and open mouths (99%) were almost exclusively directed towards m2. however, during f1–m1–m2 interactions, f1 received more behavioural events from m1 (174) than from m2 (57), with genital presents showing the greatest disparity (84 from m1 and 5 from m2). fig. 4 box plots of weekly female–male coas (a) between the males (m1 and m2) and female f1 and (b) the weekly rates per minute of male display behaviours (genital present, melon shake, head nod and flutter) towards f1 relative to weekly testosterone (t) concentrations in blow. ‘rising t’ lasted from the first weekly concentration above the individual’s annual mean concentration that was followed by a second consecutive week above the mean until the peak weekly concentration. ‘falling t’ lasted from the week immediately following the peak concentration until the last week prior to the week before the concentration fell below the mean for at least two consecutive weeks. ‘baseline t’ corresponds to all other weeks. f1’s receptivity to genital present displays genital presents performed towards f1’s lateral surface were most frequent (84% of all genital presents), with approximately equal frequency towards f1’s left or right side. m1 presented towards f1’s ventral surface (11% of genital presents) more often than m2 (4% of genital presents). males performed this behaviour with their long axis parallel to the bottom or with their head angled down towards the bottom; there were no observations of this behaviour with the male’s head angled towards the surface. this behaviour was not performed by either male at the water’s surface. the identity of the male performing a genital present had a large effect on f1’s receptivity scores (d = 1.13). f1’s receptivity towards genital present displays from m1 was higher on average and reached higher scores than receptivity towards m2’s genital present displays (m1: 2.58 ± 1.02, range = 1–6; m2: 1.60 ± 0.94, range = 0–4; fig. 5). f1 slowed her swim speed during genital presents to match m1’s pace during genital present (68% of displays) more often than during m2’s displays (27%), resulting in higher rates of contact during m1’s displays (19% vs. 2%). f1 never actively distanced herself from m1’s displays but did so for 21% of m2’s displays. f1 rolled her dorsal surface towards the displaying male during 15% of m1’s displays and 31% of m2’s. f1’s receptivity to genital present displays during inferred follicular phases was 2.53 ± 1.05 for m1 and 1.45 ± 1.10 for m2. in both observations of genital presents from m1 with an erection, f1 rolled her ventral surface away from m1, and contact did not occur. fig. 5 female f1’s receptivity score by male (m1 and m2) performing the genital present. the solid line within the box represents the median, and the dashed line represents the mean. discussion the behaviour and physiology of beluga whales were simultaneously investigated for the first time in this study, with hormone measurements in blow providing important contextual information required to interpret behavioural observations. exclusively continuous behavioural sampling during observation sessions conducted year-round from an underwater vantage point provided detailed descriptions of social behaviour that are logistically impossible to perform on wild belugas. despite the limitations imposed by social grouping and a small sample size, patterns of behaviour were observed that are consistent with beluga behaviour in aquaria (hill et al. 2018) and the wild. the seasonality of female–male association in this study approximates the seasonal sexual segregation observed in wild belugas (michaud 2005; loseto et al. 2006). the lack of apparent seasonality in male–male interactions is consistent with the importance of these associations in wild belugas (o’corry-crowe et al. 2020). the high frequencies of female–male association during the time of year when belugas are difficult to observe in the wild emphasise the value of longitudinal studies within aquaria in complementing studies of wild belugas. blow sampling for reproductive hormone analysis has value in the longitudinal monitoring of individual animals, as employed in this study (richard, robeck et al. 2017). repeated sampling enabled the identification of f1’s oestrous cycles, which was critical to interpreting patterns of female–male behaviour. in the absence of ultrasonographic or urinary hormone conjugate data, a conservative standard for identifying luteal phases based on previous validations performed with the same animal (richard, robeck et al. 2017) was applied to reduce the likelihood of falsely identifying an oestrous cycle. the first two inferred oestrous cycles identified demonstrated expected oestrous cycle stage durations (steinman et al. 2012), occurred when oestrous cycles frequently occur (robeck, monfort et al. 2005) and had female–male behavioural correlates. the third oestrous cycle identified was less clearly interpreted, fell during a time when oestrous cycles are less likely to oestrous (robeck, monfort et al. 2005) and lacked behavioural correlates. although aquarium belugas most often have two oestrous cycles in a given breeding season (steinman et al. 2012), there are observations of up to seven non-conceptive oestrous cycles in a single year for one female (katsumata et al. 2006). the progesterone measurement approach precluded the detection of non-ovulatory oestrous cycles, which have been observed in belugas (steinman et al. 2012). the high level of interest in f1 by the males in february (weeks 26–27; 38% of all female–male interactions and 72% of all male towards female display behaviours outside of breeding season) could be explained by a non-ovulatory cycle that was not detected via progesterone monitoring. increased frequency of blow sampling, the addition of oestradiol measurements, or ultrasound examinations at key times to confirm or refute findings from blow sampling would aid in identifying reproductive events with greater certainty, reducing reliance on inferences. however, the rigorous validation of hormone measurements in blow, for these purposes, under these sampling conditions with these belugas (richard, robeck et al. 2017) lends confidence to the physiological interpretations made in this study. patterns of male–female behaviour were influenced by f1’s reproductive condition, with markedly more frequent associations and behavioural events occurring during f1’s breeding season. there did not appear to be a difference in female–male association patterns between f1’s inferred follicular phases, when she would be expected to be most receptive, and the remaining weeks of the breeding season. the uncertainty associated with identifying oestrous cycle stages in this study could account for this observation. however, if female receptivity was the only factor influencing this behaviour, even shorter periods of relatively high female–male association would be expected. although this may be explained by the lack of additional receptive females for the males to interact with, there was no evidence of the males coercing the female to associate with them. alternatively, the observed pattern of prolonged periods of more frequent and longer female–male associations would also provide the female with opportunity to evaluate potential mates, consistent with predictions based on ovulation mode. knowledge of f1’s breeding season allowed for the description of presumed courtship behaviours through their disproportionate occurrence during the breeding season. courtship was characterised by visual displays predominantly performed by the males (genital present, melon shake, head nod and flutter). in particular, the strong correspondence of male–female genital presents with the breeding season, along with the high frequency of occurrence during that time, suggests a courtship function for this behaviour. the rarity of erections during male–female genital presents suggests a display function as opposed to attempted copulation. whilst inferred to have occurred at least three times, copulation was not observed to confirm the courtship function of these display behaviours. copulation is rarely observed in belugas in aquaria despite regular conceptions (glabicky et al. 2010; hill et al. 2015), which contrasts with other species of odontocetes in both aquaria and the wild, where copulation is commonly observed relative to sampling effort (puente & dewsbury 1976; orbach et al. 2019). a low copulation rate is consistent with predictions based on beluga reproductive physiology, necessitating 24-hour video monitoring to observe copulation and more definitively describe the function of these behaviours. the prevalence of visual displays performed by the males towards f1 would provide potential mechanisms for pre-copulatory female mate choice. although this sample was small, the observed courtship behaviours are consistent with the behavioural repertoire of belugas at several different aquaria and include behaviours not previously described in studies of socio-sexual behaviour (glabicky et al. 2010; hill et al. 2015; hill et al. 2016). visual courtship displays occurred at much higher rates than previously reported in other odontocetes, whilst tactile, aggressive/coercive or high-speed chase behaviours that characterise courtship in other odontocetes were rare or absent (wells 1984; scott et al. 2004; muraco & kucjaz 2015; orbach et al. 2019). the importance of behavioural displays would explain the apparent low investment in preor post-copulatory morphological traits in belugas relative to other cetaceans (dines et al. 2015). given the importance of vocal communication in this species (castellote et al. 2019), future studies in aquaria should prioritise obtaining vocalisation data to more fully characterise courtship behaviour. whilst female–male association and courtship behaviour coincided with f1’s breeding season, there was a weaker association with measures of male reproductive physiology. the seasonal timing of presumed courtship behaviour (primarily march through may) was consistent with previous observations of male beluga reproductive seasonality and the timing of conceptions in aquaria (robeck, monfort et al. 2005; richard, schmitt et al. 2017). the more frequent occurrence of courtship whilst testosterone and testes size were declining contrasts with spinner dolphins (stenella longirostris; wells 1984) and finless porpoises (neophocaena phocaenoides asiaeorientalis; wu et al. 2010). testosterone still likely played a role in regulating male behaviour, as both female–male association and courtship behaviour all but ceased for m1 after blow testosterone fell below the annual mean concentration. however, the low rates of female–male interaction whilst testosterone or testes size were increasing or at peak values suggest that signalling from the female indicating receptivity played an important role in eliciting courtship behaviour from the males. one potential indicator of female receptivity is a change in the willingness to swim in close association with a male. as proposed by hill et al. (2015), group swimming served an important function in beluga social interactions observed in this study. female–male group swimming occurred almost exclusively during the breeding season and was concentrated primarily in the observation sessions that also contained male–female genital presents. group swimming was not necessarily synchronous, as described in other species (connor et al. 2006), and it appeared that either the male or the female could lead the direction and pace of swimming during a group swim. swimming in this manner requires cooperation and could, therefore, be used to assess female mate choice, especially if group swimming is associated with courtship behaviours, as it was in this study. although both males were frequently simultaneously observed in a group swim with f1, courtship behaviour during these triad interactions was almost exclusively between m1 and f1. with both males available for interaction at the same time, this is perhaps indicative of f1’s choice to swim in closer association with m1 as opposed to m2 at those times. whilst female–male interactions were typically initiated by males and terminated by females in this group, this pattern was weaker during the breeding season. this could indicate a change in the female’s willingness to swim in close association with a male and receive courtship displays. this behaviour is likely affected by social grouping, but its potential function in mate choice merits further study. another potential indicator of female receptivity is the behavioural response to courtship behaviour. the slow, deliberate pace of the genital present, as well as the associated termination of active forward propulsion by the displaying male leaves a clear opportunity for the female recipient to respond in a way that either allows contact to occur or not, as well as where on the body that contact can occur. in this study, f1 was observed to variably alter her swim speed or body orientation in response to genital presents, resulting in greater receptivity towards m1’s displays. f1’s variable responses are analogous to those described in other species of odontocetes (orbach et al. 2015; orbach et al. 2017). more extensive video monitoring that captures occurrences of copulation is needed to determine if these measures of receptivity during courtship are predictors of mate choice. if pre-copulatory female mate choice is an important strategy for belugas, then behavioural traits would be expected to vary among adult males, which would precipitate the observed variation in responses from the female. even with the limited amount of observations and the small number of belugas studied, individual variation has been documented in male courtship displays. neither male performed genital presents at the water’s surface with a lateral preference as described in the ethogram created by hill et al. (2015). although f1 spent more total time associating and engaged in more courtship behaviours with m2, she preferentially swam with m1 and was more receptive to m1’s genital present displays during the periods of presumed receptivity. as a proven sire, m1 may have been better able to detect f1’s receptiveness during these periods, and therefore concentrated displays during this time. however, the absence of coercive behaviour by the males suggests a preference for m1 when f1 was inferred to be most receptive. f1’s preference for m1 during key times of the oestrous cycle may have occurred because m2 was likely immature during the study period. whilst m2 had adult levels of testosterone, his testes were approximately half the volume of mature belugas in aquaria and the wild (brodie 1971; richard, schmitt et al. 2017). most of the interactions between m2 and f1 occurred later in the breeding season and outside of inferred follicular phases. in ungulates, juvenile males may display similarly ineffective courtship behaviour (milner et al. 2007). f1’s choice to interact with m2 when she was presumably less receptive is less clearly explained, although socio-sexual interactions have been observed between adult females and juvenile males in previous studies of belugas (glabicky et al. 2010; hill et al. 2015). studies of social groups with multiple mature males are required to better understand the influence of variation of male courtship displays on female behaviour. mating systems with pre-copulatory female mate choice are often associated with sexually selected male traits (clutton-brock & mcauliffe 2009), which is consistent with the sexual dimorphism observed in belugas. the display behaviours performed by male belugas during courtship in this study seemingly emphasise sexually dimorphic traits, including body size and shape (kleinenberg et al. 1969), melon size and shape (kleinenberg et al. 1969), curling of the pectoral flippers (brodie 1989) and abdominal fat pads (werth & ford 2012). in addition, the distinctive white colouration of belugas, present in males only after the attainment of sexual maturity (kleinenberg et al. 1969; burns & seaman 1988), would facilitate the visibility of these displays in the low-light conditions of the arctic during the breeding season. studying more multi-male social groupings in aquaria would lead to a better understanding of preferred behavioural and morphological traits, and therefore the potential for sexual selection to occur. sexual dimorphism can also be associated with male–male competition for access to mates, but there was little evidence that this was important in this social group. association and genital presents between the males occurred at similar rates throughout the year, and m1 would frequently tolerate the presence of m2 whilst interacting with f1. low rates of male–male aggression suggest that male–female interactions did not function as mate guarding behaviour as described in other cetaceans (schaeff 2007), perhaps because mate guarding is less important in securing paternity among species with induced ovulation (soulsbury 2010). m2’s maturity status may explain the low rate of male–male aggression, although m2’s apparent observation of m1’s courtship behaviour towards f1 also suggests that m2 was learning to engage in courtship. social structure during the breeding season in the wild is largely unknown, but in most cases, a female would become pregnant whilst still accompanied by a nursing calf (brodie 1971). this implies that at least young calves would have an opportunity to observe courtship and mating. ontogenetic changes in male socio-sexual behaviour have been documented in one aquarium population (lilley et al. 2020), but the role of learning in that development is unknown. comparing various aquarium populations would reveal if males that are housed together show similar behaviour to each other that is different from other social groupings. whilst the sample size in this study is prohibitively small to draw broad conclusions, the results of this study are consistent with predictions resulting from the growing understanding of beluga reproductive physiology, establishing several paths for future research on beluga reproductive behaviour. continued research in this area is important because if females select mates during prolonged courtship periods, then there are critical implications for wild beluga management. in smaller populations, female belugas may have reduced opportunities for choice due to difficulty in finding mates or the inability to sample enough males for preferred phenotypes before selecting a mate (quader 2005). this is problematic because limiting opportunities for female mate choice has negatively impacted reproductive rate across a variety of taxa (møller & legendre 2001; candolin 2019). in belugas, the effects of small population sizes on mate choice may be exacerbated by anthropogenic factors. breeding behaviour may be affected by sea-ice loss, which disrupts migration patterns (o’corry-crowe et al. 2016), widens distributions (heide-jørgensen et al. 2010) and leads to an increase in the threat of killer whale predation (higdon & ferguson 2009). anthropogenic noise can mask vocal signalling that may be important in locating or selecting mates (castellote et al. 2019; mitoyen et al. 2019). selective subsistence harvests that target larger adult males (harwood et al. 2014; hobbs et al. 2015) could reduce the abundance of preferred males. these factors could combine to disrupt beluga social structures and mating systems. these potential disruptions have previously been considered as possible explanations for the failure of small beluga populations to recover (wade et al. 2012; hobbs et al. 2015), and this study has provided specific behavioural mechanisms that should be further investigated to explore this possibility. as behavioural observations of belugas with known reproductive status during the breeding season are not feasible in the wild, determining the sex ratio, age structure and kinship within a population is necessary to determine the number of potential sires available and the proportion of potential sires that are reproducing. advancing unmanned aerial vehicle sampling methodologies (centelleghe et al. 2020) could allow blow sampling for molecular purposes (richard, schultz et al. 2017) to support these efforts, especially for young animals typically excluded from biopsy sampling (citta et al. 2018). applying this study’s approach of simultaneously monitoring behaviour and physiology to larger and more diverse social groups, made possible through the application of minimally invasive blow sampling, will also be an important component of these efforts. the year-round underwater visibility of belugas in aquaria is critical, as courtship behaviour frequently occurred several feet below the surface where wild belugas are rarely observable, especially during the breeding season. knowledge gained in aquaria can be used to refine hypotheses regarding mating strategies that could help explain why beluga populations are not recovering at expected rates. conclusions minimally invasive assessments of reproductive physiology were used to contextualise behavioural observations in a group of belugas in professionally managed care. despite a small sample size, several observed patterns were consistent with the limited knowledge of social behaviour in wild belugas. whilst broad conclusions are limited by the group composition and sample size of this group of belugas, there were several findings that are consistent with predictions based on the induced mode of ovulation in this species. observations suggest that pre-copulatory female mate choice was relatively important in this group; female–male interactions during the period of receptivity for the study female were characterised by relatively long interactions, frequent display behaviours, low copulation rates and infrequent and mild aggression. potential behavioural mechanisms for female mate choice include selecting individual males to swim in close association with, preferentially initiating or terminating coordinated interactions with individual males and responding variably to display behaviours. additional studies of behaviour and physiology in aquaria and the demographics and kinship of wild populations will provide the complementary information required to validate these findings. if these mating strategies are important for wild belugas, then perhaps reduced opportunities for mate choice due to various environmental and anthropogenic factors could be limiting reproductive rate and population recovery, especially in small populations. acknowledgements this study would not have been possible without the assistance of the beluga trainers and veterinarians at mystic aquarium, especially kristine magao, lindsey nelson, kate mcelroy, kathryn justice, allyson mcnaughton and allison tuttle. behavioural observations were made possible through the contributions of daniel catizone, noël vezzi, anthony cammarano and kathleen leach. special thanks to research assistants crysania brady and renee bakker for their assistance in all aspects of the project, and to paul anderson for providing valuable guidance and suggestions. we thank the critical reading of two anonymous reviewers who helped clarify this manuscript. this constitutes scientific contribution no. 317 from the sea research foundation, inc. references bartsh s.s., johnston s.d. & siniff d.b. 1992. territorial behavior and breeding frequency of male weddell seals (leptonychotes weddelli) in relation to age, size, and concentrations of serum testosterone and cortisol. canadian journal of zoology 70, 680–692, doi: 10.1139/z92-102. brodie p.f. 1971. a reconsideration of aspects of growth, reproduction and behavior of the white whale (delphinapterus leucas) with reference to the cumberland sound, baffin island population. journal fisheries research board of canada 28, 1309–1318, doi: 10.1139/f71-198. brodie p.f. 1989. the white whale delphinapterus leucas (pallas, 1776). in s.h. ridgway & s.r. harrison (eds.): handbook of marine mammals. vol. 4: river dolphins and the larger toothed whales. pp. 119–144. new york: academic press. burgess e.a., lanyon j.m. & keeley t. 2012. testosterone and tusks: maturation and seasonal reproductive patterns of live, free-ranging male dugongs (dugong dugon) in a subtropical population. reproduction 143, 683–697, doi: 10.1530/rep-11-0434. burns j.j. & seaman g.a. 1988. investigations of belukha whales in coastal waters of western and northern alaska. ii. biology and ecology. final report. outer continental shelf environmental assessment program. fairbanks, ak: alaska department of fish & game. cairns s.j. & schwager s.j. 1987. a comparison of association indices. animal behaviour 35, 1454–1469, doi: 10.1016/s0003-3472(87)80018-0. candolin u. 2019. mate choice in a changing world. biological reviews 94, 1246–1260, doi: 10.1111/brv.12501. castellote m., thayre b., mahoney m., mondragon j., lammers m.o. & small r.j. 2019. anthropogenic noise and the endangered cook inlet beluga whale, delphinapterus leucas: acoustic considerations for management. marine fisheries review 80(3), 63–88, doi: 10.7755/mfr.80.3.3. centelleghe c., carraro l., gonzalvo j., rosso m., esposti e., gili c., bonato m., pedrotti d., cardazzo b., povinelli m. & mazzariol s. 2020. the use of unmanned aerial vehicles (uavs) to sample the blow microbiome of small cetaceans. plos one 15, e0235537, doi: 10.1371/journal.pone.0235537. citta j.j., o’corry‐crowe g., quakenbush l.t., bryan a.l., ferrer t., olson m.j., hobbs r.c. & potgieter b. 2018. assessing the abundance of bristol bay belugas with genetic mark–recapture methods. marine mammal science 34, 666–686, doi: 10.1111/mms.12472. clutton-brock t. & mcauliffe k. 2009. female mate choice in mammals. the quarterly review of biology 84, 3–27, doi: 10.1086/596461. connor r.c., smolker r. & bejder l. 2006. synchrony, social behaviour and alliance affiliation in indian ocean bottlenose dolphins, tursiops aduncus. animal behaviour 72, 1371–1378, doi: 10.1016/j.anbehav.2006.03.014. dines j.p., mesnick s.l., ralls k., may-collado l., agnarsson i. & dean m.d. 2015. a trade-off between precopulatory and postcopulatory trait investment in male cetaceans. evolution 69, 1560–1572, doi: 10.1111/evo.12676. dipaola s., akai c. & kraus b. 2007. experiencing belugas: action selection for an interactive aquarium exhibit. adaptive behavior 15, 99–113, doi: 10.1177/1059712306076251. glabicky n., dubrava a. & noonan m. 2010. social–sexual behavior seasonality in captive beluga whales (delphinapterus leucas). polar biology 33, 1145–1147, doi: 10.1007/s00300-010-0790-3. hänninen l. & pastell m. 2009. cowlog: open-source software for coding behaviors from digital video. behavior research methods 41, 472–476, doi: 10.3758/brm.41.2.472. harwood l.a., kingsley m.c.s. & smith t.g. 2014. an emerging pattern of declining growth rates in belugas of the beaufort sea: 1989–2008. arctic 67, 483–492, doi: 10.14430/arctic4423. heide-jørgensen m.p., laidre k.l., borchers d., marques t.a., stern h. & simon m. 2010. the effect of sea-ice loss on beluga whales (delphinapterus leucas) in west greenland. polar research 29, 198–208, doi: 10.1111/j.1751-8369.2009.00142.x. higdon j.w. & ferguson s.h. 2009. loss of arctic sea ice causing punctuated change in sightings of killer whales (orcinus orca) over the past century. ecological applications 19, 1365–1375, doi: 10.1890/07-1941.1. hill h.m., alvarez c.j., dietrich s. & lacy k. 2016. preliminary findings in beluga (delphinapterus leucas) tactile interactions. aquatic mammals 42, 277–291, doi: 10.1578/am.42.3.2016.277. hill h.m., de oliveira silva-gruber d.g. & noonan m. 2018. sex-specific social affiliation in captive beluga whales (delphinapterus leucas). aquatic mammals 44, 250–255, doi: 10.1578/am.44.3.2018.250. hill h.m., dietrich s., yeater d., mckinnon m., miller m., aibel s. & dove a. 2015. developing a catalog of socio-sexual behaviors of beluga whales (delphinapterus leucas) in the care of humans. animal behaviour and cognition 2, 105–123, doi: 10.12966/abc.05.01.2015. hobbs r.c., wade p.r. & shelden k.e.w. 2015. viability of a small, geographically-isolated population of beluga whales, delphinapterus leucas: effects of hunting, predation, and mortality events in cook inlet, alaska. marine fisheries review 77, 59–88, doi: 10.7755/mfr.77.2.4. høier r. & heide-jørgensen m.p. 1994. steroid hormones and prolactin in white whales (delphinapterus leucas) from west greenland. bioscience 39, 227–238. iossa g., soulsbury c.d., baker p.j. & harris s. 2008. sperm competition and the evolution of testes size in terrestrial mammalian carnivores. functional ecology 22, 655–662, doi: 10.1111/j.1365-2435.2008.01409.x. katsumata e., furuta c., katsumata h., watanabe g. & taya k. 2006. basal body temperature method for detecting ovarian cycle in the captive beluga (delphinapterus leucas). journal of reproduction and development 52, 59–63, doi: 10.1262/jrd.17066. kaufman a.b. & rosenthal r. 2009. can you believe my eyes? the importance of interobserver reliability statistics in observations of animal behaviour. animal behaviour 78, 1487–1491, doi: 10.1016/j.anbehav.2009.09.014. kelley t.c., stewart r.e.a., yurkowski d.j., ryan a. & ferguson s.h. 2014. mating ecology of beluga (delphinapterus leucas) and narwhal (monodon monoceros) as estimated by reproductive tract metrics. marine mammal science 31, 479–500, doi: 10.1111/mms.12165. kleinenberg s.e., yablokov a.v., bel’kovich b.m. & tarasevich m.n. 1969. beluga (delphinapterus leucas): investigation of the species. jerusalem: israel program for scientific translations. lacey e.a., wieczorek j.r. & tucker p.k. 1997. male mating behaviour and patterns of sperm precedence in arctic ground squirrels. animal behaviour 53, 767–779, doi: 10.1006/anbe.1996.0342. lilley m.k., ham j.r. & hill h.m. 2020. the development of socio-sexual behaviour in belugas (delphinapterus leucas) under human care. behavioural processes 171, 104025, doi: 10.1016/j.beproc.2019.104025. loseto l.l., richard p., stern g.a., orr j. & ferguson s.h. 2006. segregation of beaufort sea beluga whales during the open-water season. canadian journal of zoology 84, 1743–1751, doi: 10.1139/z06-160. mann j. 2006. establishing trust: socio-sexual behavior and the development of male–male bonds among indian ocean bottlenose dolphins. in v. sommer & p.l. vasey (eds.): homosexual behavior in animals: an evolutionary perspective. pp. 107–130. new york: cambridge university press. martin p. & bateson p. 2007. measuring behavior: an introductory guide. 3rd edn. cambridge: cambridge university press. michaud r. 2005. sociality and ecology of the odontocetes. in k.e. ruckstuhl & p. neuhaus (eds.): sexual segregation in vertebrates: ecology of the two sexes. pp. 303–326. new york: cambridge university press. milner j.m., nilsen e.b. & andreassen h.p. 2007. demographic side effects of selective hunting in ungulates and carnivores. conservation biology 21, 36–47, doi: 10.1111/j.1523-1739.2006.00591.x. mitoyen c., quigley c. & fusani l. 2019. evolution and function of multimodal courtship displays. ethology 125, 503–515, doi: 10.1111/eth.12882. møller a.p. & legendre s. 2001. allee effect, sexual selection and demographic stochasticity. oikos 92, 27–34, doi: 10.1034/j.1600-0706.2001.920104.x. muraco h. & kuczaj s.a. 2015. conceptive estrus behavior in three bottlenose dolphins (tursiops truncatus). animal behavior and cognition 2, 30–48, doi: 10.12966/abc.02.03.2015. neimanis a.s., read a.j., foster r.a. & gaskin d.e. 2000. seasonal regression in testicular size and histology in harbor porpoises (phocoena phocoena) from the bay of fundy and gulf of maine. london journal of zoology 250, 221–229, doi: 10.1111/j.1469-7998.2000.tb01072.x. o’brien j.k., steinman k.j., schmitt t. & robeck t.r. 2008. semen collection, characterization and artificial insemination in the beluga (delphinapterus leucas) using liquid-stored spermatozoa. reproduction, fertility and development 20, 770–783, doi: 10.1071/rd08031. o’corry-crowe g.m., mahoney a.r., suydam r., quakenbush l., whiting a., lowry l. & harwood l. 2016. genetic profiling links changing sea-ice to shifting beluga whale migration patterns. biology letters 12, 20160404, doi: 10.1098/rsbl.2016.0404. o’corry-crowe g.m., suydam r., quakenbush l., smith t.g., lydersen c., kovacs k.m., orr j., harwood l., litovka d. & ferrer t. 2020. group structure and kinship in beluga whale societies. scientific reports 10, 11462, doi: 10.1038/s41598-020-67314-w. o’corry-crowe g.m., suydam r.s., rosenberg a., frost k.j. & dizon a.e. 1997. phylogeography, population structure and dispersal patterns of the beluga whale delphinapterus leucas in the western nearctic revealed by mitochondrial dna. molecular ecology 6, 955–970, doi: 10.1046/j.1365-294x.1997.00267.x. orbach d.n., kelly d.a., solano m. & brennan p.l.r. 2017. genital interaction during simulated copulation among marine mammals. proceedings of the royal society b 284, article no. 20171265, doi: 10.1098/rspb.2017.1265. orbach d.n., packard j.m., keener w., ziltener a. & würsig b. 2019. testes size, vaginal complexity, and behavior in toothed whales (odontocetes): arms race or tradeoff model for dusky dolphins (lagenorhynchus obscurus), harbor porpoises (phocoena phocoena), and bottlenose dolphins (tursiops spp.)? journal of comparative psychology 133, article no. 359, doi: 10.1037/com0000162. orbach d.n., packard j.m., kirchner t. & würsig b. 2015. evasive behaviours of female dusky dolphins (lagenorhynchus obscurus) during exploitative scramble competition. behaviour 152, 1953–1977, doi: 10.1163/1568539x-00003310. puente a.e. & dewsbury d.a. 1976. courtship and copulatory behavior of bottlenose dolphins (tursiops truncatus). cetology 21, 1–9. quader s. 2005. mate choice and its implications for conservation and management. current science 89, 1220–1229. r core team 2020. r: a language and environment for statistical computing. vienna: r foundation for statistical computing. richard j.t., robeck t.r., osborn s.d., naples l., mcdermott a., laforge r., romano t.a. & sartini b.l. 2017. testosterone and progesterone concentrations in blow samples are biologically relevant in belugas (delphinapterus leucas). general and comparative endocrinology 246, 183–193, doi: 10.1016/j.ygcen.2016.12.006. richard j.t., schmitt t., haulena m., vezzi n., dunn j.l., romano t.a. & sartini b.l. 2017. seasonal variation in testes size and density detected in belugas (delphinapterus leucas) using ultrasonography. journal of mammalogy 98, 874–884, doi: 10.1093/jmammal/gyx032. richard j.t., schultz k., goertz c., hobbs r., romano t.a. & sartini b.l. 2017. assessing the quantity and downstream performance of dna isolated from beluga (delphinapterus leucas) blow samples. aquatic mammals 43, 398–408, doi: 10.1578/am.43.4.2017.398. robeck t.r., monfort s.l., calle p.p., dunn j.l., jensen e., boehm j.r., young s. & clark s.t. 2005. reproduction, growth and development in captive beluga (delphinapterus leucas). zoo biology 24, 29–49, doi: 10.1002/zoo.20037. robeck t.r., schneyer a.l., mcbain j.f., dalton l.m., walsh m.t., czekala n.m. & kraemer d.c. 1993. analysis of urinary immunoreactive steroid metabolites and gonadotropins for characterization of the estrous cycle, breeding period, and seasonal estrous activity of captive killer whales (orcinus orca). zoo biology 12, 173–187, doi: 10.1002/zoo.1430120204. robeck t.r., steinman k.j., yoshioka m., jensen e., o’brien j.k., katsumata e., gili c., mcbain j.f., sweeney j. & monfort s.l. 2005. estrous cycle characterization and artificial insemination using frozen-thawed spermatozoa in the bottlenose dolphin (tursiops truncatus). reproduction 129, 659–674, doi: 10.1530/rep.1.00516. schaeff c.m. 2007. courtship and mating behavior. in d.l. miller (ed.): reproductive biology and phylogeny of cetacea: whales, dolphins, and porpoises. pp. 349–370. enfield, nh: science publishers. schroeder j.p. & keller k.v. 1989. seasonality of serum testosterone levels and sperm density in tursiops truncatus. the journal of experimental zoology 249, 316–321, doi: 10.1002/jez.1402490310. scott e.m., mann j., watson-capps j.j., sargeant b.l. & connor r.c. 2004. aggression in bottlenose dolphins: evidence for sexual coercion, male–male competition, and female tolerance through analysis of tooth-rake marks and behaviour. behaviour 142, 21–44, doi: 10.1163/1568539053627712. soulsbury c.d. 2010. ovulation mode modifies paternity monopolization in mammals. biology letters 6, 39–41, doi: 10.1098/rsbl.2009.0703. soulsbury c.d. & iossa g. 2010. the impact of ovulation mode on sperm quantity and quality in mammals. evolutionary ecology 24, 879–889, doi: 10.1007/s10682-009-9344-y. steinman k.j., o’brien j.k., monfort s.l. & robeck t.r. 2012. characterization of the estrous cycle in female beluga (delphinapterus leucas) using urinary endocrine monitoring and transabdominal ultrasound: evidence of facultative induced ovulation. general and comparative endocrinology 175, 389–397, doi: 10.1016/j.ygcen.2011.11.008. wade p.r., reeves r.r. & mesnick s.l. 2012. social and behavioral factors in cetacean responses to overexploitation: are odontocetes less “resilient” than mysticetes? journal of marine biology 2012(2), article no. 567276, doi: 10.1155/2012/567276. wells r.s. 1984. reproductive behavior and hormonal correlates in hawaiian spinner dolphins, stenella longirostris. reports to the international whaling commission special issue 6, 465–472. werth a.j. & ford t.j. jr. 2012. abdominal fat pads act as control surfaces in lieu of dorsal fins in the beluga (delphinapterus). marine mammal science 28, 516–527, doi: 10.1111/j.1748-7692.2012.00567.x. wingfield j.c., hegner r.e., dufty a.m. jr. & ball g.f. 1990. the “challenge hypothesis”: theoretical implications for patterns of testosterone secretion, mating systems, and breeding strategies. the american naturalist 136, 829–846, doi: 10.1086/285134. wu h., hao y., yu x., xian y., zhao q., chen d., kuang x., kou z., feng k., gong w. & wang d. 2010. variation in sexual behaviors in a group of captive male yangtze finless porpoises (neophocaena phocaenoides asiaeorientalis): motivated by physiological changes? theriorgenology 74, 1467–1475, doi: 10.1016/j.theriogenology.2010.06.018. doi:10.3402/polar.v35.25405 r e s e a r c h / r e v i e w a r t i c l e arctic plants are capable of sustained responses to long-term warming robert t. barrett1,2 & robert d. hollister1 1 biology department, grand valley state university, 1 campus drive, allendale, mi 49401, usa 2 west michigan academy of environmental science, 4463 leonard street, walker, mi 49534, usa keywords species traits; international tundra experiment; meta-analysis; plant�climate interactions; tundra vegetation; warming response. correspondence robert t. barrett, west michigan academy of environmental science, 4463 leonard street, walker, mi 49534, usa. e-mail: robertbarrett@choiceschools.com abstract previous studies have shown that arctic plants typically respond to warming with increased growth and reproductive effort and accelerated phenology, and that the magnitude of these responses is likely to change over time. we investigated the effects of long-term experimental warming on plant growth (leaf length) and reproduction (inflorescence height, reproductive phenology and reproductive effort) using 17�19 years of measurements collected as part of the international tundra experiment (itex) at sites near barrow and atqasuk, alaska. during the study period, linear regressions indicated non-significant tendencies towards warming air temperatures at our study sites. results of our meta-analyses on the effect size of experimental warming (calculated as hedges’ d) indicated species generally responded to warming by increasing inflorescence height, increasing leaf length and flowering earlier, while reproductive effort did not respond consistently. using weighted least-squares regressions on effect sizes, we found a significant trend towards dampened response to experimental warming over time for reproductive phenology. this tendency was consistent, though non-significant, across all traits. a separate analysis revealed significant trends towards reduced responses to experimental warming during warmer summers for all traits. we therefore propose that tendencies towards dampened plant responses to experimental warming over time are the result of regional warming. these results show that arctic plants are capable of sustained responses to warming over long periods of time but also suggest that, as the region continues to warm, factors such as nutrient availability, competition and herbivory will become more limiting to plant growth and reproduction than temperature. to access the supplementary material for this article, please see the supplementary file under article tools, online. in recent decades, climate change has been impacting terrestrial ecosystems worldwide (stocker et al. 2013). the responses of arctic ecosystems have been of particular interest as the arctic has been warming faster and with greater magnitude than other regions (symon et al. 2005; stocker et al. 2013). the impact of climate change on the arctic has been of particular interest owing to its importance regulating energy balance and the global carbon budget (chapin et al. 2000; symon et al. 2005; aerts 2006). as tundra plants play crucial roles in these processes, understanding their response to warming is critical to predicting how the arctic will respond to climate change. experimental and observational studies have shown that arctic plants typically respond to warming with increased growth and reproduction and accelerated phenology (chapin et al. 1995; arft et al. 1999; hollister et al. 2005). regional warming in the arctic has also been associated with shrub expansion, shifts in plant polar research 2016. # 2016 r.t. barrett & r.d. hollister. this is an open access article distributed under the terms of the creative commons attributionnoncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2016, 35, 25405, http://dx.doi.org/10.3402/polar.v35.25405 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/25405/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/25405/0 http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/25405 http://dx.doi.org/10.3402/polar.v35.25405 community composition, altered trophic interactions and changes in energy balance (chapin et al. 2005; post et al. 2008). in assessing the impacts of climate change on plant species, one factor that remains unclear is how long the response of plants to warming can be maintained. although ambient temperatures in the arctic are typically lower than those optimal for photosynthesis in tundra species, it has been assumed that arctic ecotypes are poorly equipped to respond to long-term warming as a result of their metabolic and photosynthetic adaptations to life in cold climates (billings & mooney 1968; bliss 1971; chapin & chapin 1981; chapin & shaver 1985a). this idea has been supported by transplant studies, which indicated that tundra species are likely to have difficulty surviving, growing and reproducing in significantly warmer conditions (chapin & chapin 1981; shaver & kummerow 1992; bennington et al. 2012). hence, a prevailing thought has been that, when subjected to warmer temperatures, arctic plants would exhibit shortterm gains in growth and reproduction, followed by a diminished response as the plants exhausted their belowground carbohydrate and nutrient stores (shaver & kummerow 1992; chapin et al. 1995; shaver & jonasson 1999). previous studies have seemingly supported this hypothesis as initial plant responses to warming decreased after a few years of exposure to experimental warming (chapin & chapin 1981; arft et al. 1999). however, this line of thought is not supported by longterm field studies that have shown that arctic plants continue to respond to warming after two decades of consistent exposure (hudson & henry 2009; hudson et al. 2011; elmendorf et al. 2012). while more studies have focused on how long-term warming affects arctic plant community composition (elmendorf et al. 2012; hedenås et al. 2012; michelsen et al. 2012), less attention has been given to the how growth, reproduction and phenological responses of individual species are affected by long-term warming (hudson et al. 2011; klady et al. 2011; campioli et al. 2013). to better understand how plant trait responses to warming change over time, we examined the responses of arctic plants to 17�19 years of experimental warming using four study sites that are part of itex. data from these sites have been used in previous analyses examining short-term community and species-level responses to warming (hollister, webber & bay 2005; hollister, webber & tweedie 2005; oberbauer et al. 2007), and in more recent studies examining longer term responses of tundra plants to temperature (elmendorf et al. 2012; oberbauer et al. 2013). by examining findings from these long-term research sites, we sought to answer the following questions: (1) how did plants at these sites respond to long-term experimental warming and are responses comparable to those found in other studies? (2) how did responses to experimental warming vary over time and with respect to summer temperature? materials and methods study sites and experimental design this study took place at field sites near barrow and atqasuk, alaska. we collected data at two sites at each location*one in dry heath tundra and the other in wet meadow tundra. the bd and bw sites were established in 1994 and 1995, respectively, while the ad and aw sites were established in 1996. for this analysis, we used plant trait data from the following years: 1994�2001, 2007�08 and 2010�12. each site included 48 permanently established plots of vegetation (ca. 1 m 2 ), half of which were randomly assigned to be experimentally warmed using open-top chambers. for comprehensive details on these sites, see hollister (2003). temperature measures we collected temperatures at each site using sensors* model 107 temperature probe (campbell scientific), hobo temperature logger (onset computer corporation) or stowaway temperature logger (onset computer corporation)*placed in six-plate radiation shields at 10�15 cm above ground surface. readings were taken every 10�60 min, then averaged and recorded every hour (campbell scientific cr10x datalogger, hobo or stowaway temperature logger). as noted above, we used a number of different sensors to measure canopy height temperature in a plot. in 1998, data loggers were installed at the sites which measured screen and canopy height temperature as well as a host of other metrics. prior to 1998, screen height temperatures were estimated from weather stations located within 3 km of the sites. snowmelt dates were determined through visual confirmation or, when researchers were not present for this event, using the day of year that the average soil surface temperatures remained above 08c at the site. soil temperature at each site was measured with probes reported abbreviations in this article ad: atqasuk dry site aw: atqasuk wet site bd: barrow dry site bw: barrow wet site itex: international tundra experiment tdd: thawing degree days from snowmelt arctic plant responses to long-term warming r.t. barrett & r.d. hollister 2 (page number not for citation purpose) citation: polar research 2016, 35, 25405, http://dx.doi.org/10.3402/polar.v35.25405 http://www.polarresearch.net/index.php/polar/article/view/25405 http://dx.doi.org/10.3402/polar.v35.25405 elsewhere (hollister et al. 2006). in cases where temperature readings were not available because of instrument malfunction, readings from the paired site or the nearby weather station were substituted (hollister et al. 2006). these cases were less than 5% of all readings. the resulting hourly temperature readings for the site were used to calculate tdd by summing average temperatures above 08c daily from first snow-free date until august 15. plant traits this study was designed to examine traits of many species over many years. therefore, only a few plant traits were monitored annually based on the comparability across species and the ease of measuring consistently. traits were chosen from those which other researchers agreed to collect using a common protocol for itex study sites (molau 1993; arft et al. 1999). the following traits were examined: inflorescence height, leaf length, reproductive effort and reproductive phenology. inflorescence height was measured as distance from ground to the tip of the inflorescence in forbs and graminoids and as the length from inflorescence base to tip in shrubs. leaf lengths were measured as the length from the base of a plant to the tip of its longest leaf in graminoids and forbs, except potentilla hyparctica and stellaria laeta, for which leaf length was described as the distance from the base to the tip of the longest leaf. this same method was used for shrubs, except cassiope tetragona, for which annual growth increments were used as leaf length. for both traits, we used the average maximum size of an individual based on one to six individuals per plot, depending on abundance (we monitored up to three marked individuals per plot and to ensure that we recorded reproductive traits we measured the three largest flowering individuals per plot). we defined reproductive effort as either the number of flowers or number of inflorescences produced by a species in a given plot, depending on the morphology of the species. similarly, reproductive phenology was defined as either the first day of year an inflorescence appeared or first day of year anthesis or stigma activation was observed in a plot. plants were monitored for each trait multiple times per week in each plot, with the exception of plots during 2001 when only 10 plots of each treatment could be observed owing to logistical constraints. detailed information on the plant trait measured for each species is provided in hollister (2003). statistical analyses we used simple linear regressions performed in r to investigate the possible trends in ambient summer temperatures, represented as tdd, at each study site over time (r development core team 2005). not all measurements were made each year on each plant species and only a few species were abundant across a site. thus, analysis was constrained to species for which a given trait was measured in at least five plots per treatment during a given year and met this criterion for at least five years during the study period (see supplementary table s1 for mean, sd and sample size of all plant traits included in the analysis organized by trait, site, species and year). response to experimental warming was determined for each species and trait using effect sizes calculated as hedges’ d, which is the difference between the averages of the control (x c ) and warmed (x e ) traits for each species divided by their pooled sd (s) and multiplied by a term to correct for small sample size. this test statistic is found as d ¼ ðx e � x cþ s � 1 � 3 4ðne þ nc � 2þ� 1 ! ; where ne and nc are the sample sizes of the control and warmed plants, respectively. this method treated each species, trait and year as an individual study. the studies were then also pooled by site and growth form within a site. performing analyses this way allowed us to directly compare our findings to those of similar studies (arft et al. 1999; rosenberg et al. 2000; dormann & woodin 2002). we performed two additional analyses; one to assess whether effect sizes of experimental warming were changing over time and another to discern if there was a relationship between effect sizes of experimental warming and summer temperature. both analyses were performed using effect sizes calculated as hedges’ d as described above, but here the average plant trait values for each study site and year were treated as an individual study (thus the sample size for each point was the number of species that occurred at the site). we then used weighted least-squares regressions to assess trends in effect sizes for each site over time and with respect to summer temperatures (tdd). metawin version 2.1 was used for these analyses (rosenberg et al. 2000). effect sizes were considered significant when their 95% confidence interval did not overlap with an effect size of zero. results temperature measurements during the time of this study, temperatures in control plots showed non-significant warming tendencies over time at all four sites (fig. 1; ad p �0.50, aw p �0.28, r.t. barrett & r.d. hollister arctic plant responses to long-term warming citation: polar research 2016, 35, 25405, http://dx.doi.org/10.3402/polar.v35.25405 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/25405/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/25405/0 http://www.polarresearch.net/index.php/polar/article/view/25405 http://dx.doi.org/10.3402/polar.v35.25405 bd p �0.31, bw p �0.15). the chambers warmed the plots on average for the summer between 0.4 and 2.28c depending on the site and year (see supplementary table s2). plant responses to long-term experimental warming species generally responded to experimental warming with increased inflorescence heights, earlier reproductive phenology and increased leaf lengths, but responses of reproductive effort were not consistent (supplementary table s3). when experimentally warmed, 79% of the species grew taller inflorescences and 51% grew longer leaves. fewer species responded to experimental warming with a change in reproductive phenology (35%), but significant responders always flowered earlier when warmed. even fewer species (29%) showed a significant response to experimental warming with respect to reproductive effort, and roughly equal numbers of species had increased or decreased reproductive efforts when warmed. variation in response to experimental warming over time and with summer temperature plant responses to experimental warming were mostly consistent, with the exception of reproductive phenology, which showed a significant (p �0.03) trend towards decreasing effect sizes over time (fig. 2c). however, we also note that inflorescence height, leaf length and reproductive effort each showed non-significant tendencies towards reduced effect sizes over time (fig. 2). for all four traits, we found significant trends towards reduced response to experimental warming during warmer summers (fig. 3). discussion the results of this study are generally consistent with, or confirm, previous studies. what makes this study unique and of interest is not that the findings are novel, but rather that they are consistent with earlier studies despite the fact that this study has now examined response over 17� 19 years of experimental treatment. this study suggests that the overall response of tundra plants to experimental warming is relatively constant. like previous studies, the most consistent response to experimental warming observed was an increase in inflorescence heights; this has been observed in earlier studies on the same plots (hollister, webber & bay 2005; hollister, webber & tweedie 2005) and in previous short-term studies on tundra plants (arft et al. 1999; gugerli & bauert 2001). while few long-term studies report the effects of experimental warming on the inflorescence heights of individual species, other data from long-term studies are consistent with our results, showing that overall plant height increases with warming (hudson et al. 2011) and that reproductive biomass typically increases with warming (klady et al. 2011; campioli et al. 2013). experimental warming significantly increased the leaf lengths of many of our plant species equating to an average increase of 9% in total leaf length. similarly, dormann & woodin (2002) found that warming increased plant leaf traits (e.g., size and length) by approximately 15% over a shorter period of time as the studies they included in their analysis had been warmed for typically fewer than five years. the overall effect size we report for warming on leaf length over 17�19 years of treatment was also similar to that reported in the earlier short-term study by arft et al. (1999), which found an effect size of approximately 0.4 during the second and third years of warming treatment. hudson et al. (2011) reported significant increases in leaf length and size over 16 years of warming in arctic canada. other studies have also noted an increase in photosynthetic biomass and productivity over extended periods of warming (boelman et al. 2003; michelsen et al. 2012; natali et al. 2012). these results, combined with those of our study, suggest that vegetative growth is capable of responding to warming over extended periods of time until temperatures are no longer a limiting factor. reproductive phenology typically accelerated with warming, significantly so for 35% of species at our sites. fig. 1 temperatures over time at the four study sites. symbols represent average thawing degree days totals (tdd) for the summer at a given site in a given year. the sample size was the number of years of the experiment (19 at barrow dry, 18 at barrow wet and 17 at both atqasuk sites). arctic plant responses to long-term warming r.t. barrett & r.d. hollister 4 (page number not for citation purpose) citation: polar research 2016, 35, 25405, http://dx.doi.org/10.3402/polar.v35.25405 http://www.polarresearch.net/index.php/polar/rt/suppfiles/25405/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/25405/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/25405/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/25405/0 http://www.polarresearch.net/index.php/polar/article/view/25405 http://dx.doi.org/10.3402/polar.v35.25405 arft et al. (1999) also found that warming over a short period of time significantly accelerated flowering for many species, resulting in relatively large effect sizes, especially after the first year of treatment. similar results have been found in earlier studies where warming led to earlier flowering (dunne et al. 2003; hollister, webber & bay 2005) and in numerous observational studies where warmer air temperatures were associated with earlier flowering (thórhallsdóttir 1998; post & forchhammer 2008). however, some studies have also found a delay in flowering date under warmer conditions (dorji et al. 2013). it should also be noted that some species appear to be reaching a threshold whereby flower timing cannot accelerate further, as has been suggested by iler & inouye (2013). reproductive effort was not typically affected by warming treatment at our sites. arft et al. (1999) also found that overall reproductive effort was not significantly impacted by warming across a variety of sites over four years of warming. similar results have been observed in other short-term studies on tundra and sub-alpine plants where effects of warming on reproductive effort showed a high degree of variability between species and years (lambrecht et al. 2007; dorji et al. 2013). in contrast to our findings, a long-term study in arctic canada (klady et al. 2011) found that plants exposed to 12 years of warming had significant increases in reproductive effort. conflicting results between these studies could be explained by the differences in geographic location. arft et al. (1999) proposed that it would be more beneficial for plants in the high arctic to respond to warming with increased reproductive efforts as they presumably faced less competition over resources from their neighbours, reducing the advantage to producing a taller canopy whereas low arctic plants would face such competition and be in need of a more immediate growth response to outcompete neighbouring species. our study was consistent with this hypothesis as our colder sites in barrow showed significant effect sizes for warming on average inflorescence heights (bd �0.98, bw �0.69) and fig. 2 relationship between year and effect size of experimental warming on plant traits (a) inflorescence height, (b) leaf length, (c) reproductive phenology and (d) reproductive effort. each point represents the effect size (calculated as hedges’ d) of experimental warming on one plant trait at one study site for a given year. equations and p values are given for significant weighted least-squares regressions (shown with solid line). for (c), reproductive phenology n �43; for other traits n �39. r.t. barrett & r.d. hollister arctic plant responses to long-term warming citation: polar research 2016, 35, 25405, http://dx.doi.org/10.3402/polar.v35.25405 5 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25405 http://dx.doi.org/10.3402/polar.v35.25405 average flowering dates (bd � �3.84, bw � �1.48) while our relatively warmer sites in atqasuk did not. compared to our sites, those examined in klady et al. (2011) are much farther north and future studies could help discern whether these differences are plastic responses to environmental factors or genetic adaptations within different ecotypes. plant responses to warming remained largely consistent over the study period. however, reproductive phenology showed a significant trend towards reduced responses to warming over time. although the results of regression analyses on other plant traits were non-significant, they were consistent with a diminishing experimental warming response over time (fig. 2). the general warming trend of the region is the likely explanation for this trend towards a diminished magnitude of response over time given the strong evidence that the effect of warming on plant traits decreases with warming ambient conditions. in other words, plants respond less to experimental warming in warmer years, and the later years of the study were generally warmer. earlier studies (chapin et al. 1995; arft et al. 1999) anticipated, and found evidence of, transient warming responses whereby plants initially responded to warming through an increase in growth and reproduction followed by a greatly diminished response. this pattern was expected because arctic plants are adapted to respond to improved summer conditions through accelerated growth and reproduction, at the cost of resources in underground storage (shaver & kummerow 1992). however, warmed plants at sites with low average temperatures and high interannual variability could still be receiving the recovery time necessary to replenish their nutrient and carbohydrate stores during cooler years, utilizing these stores during warmer years. this could explain discrepancies between our results and those of transplant studies where plants in drastically and consistently warmer conditions may not have adequate time to replenish resources. given that the magnitude of warming response showed a much stronger trend with seasonal temperature than the duration of experimental warming, we conclude that plants are able to sustain their responses to warming for longer periods of time than previously suggested. yet, we also note that temperatures are nearing thresholds where fig. 3 relationship between seasonal temperature (tdd) and effect size of experimental warming on plant traits (a) inflorescence height, (b) leaf length, (c) reproductive phenology and (d) reproductive effort. see fig. 2. arctic plant responses to long-term warming r.t. barrett & r.d. hollister 6 (page number not for citation purpose) citation: polar research 2016, 35, 25405, http://dx.doi.org/10.3402/polar.v35.25405 http://www.polarresearch.net/index.php/polar/article/view/25405 http://dx.doi.org/10.3402/polar.v35.25405 other factors will become limiting. therefore, we forecast that plants at our sites will shift from being temperaturelimited to being constrained by other abiotic factors as the region warms due to climate change. this may already be the case for reproductive phenology at our sites and suggests that some plant species are reaching a threshold in warm years where they are incapable of flowering earlier, as iler & inouye (2013) have proposed. while we present evidence that summer growing temperatures will become less limiting for plant growth and reproduction over time, we have yet to quantify the impacts of abiotic conditions during the winter and spring seasons, both of which can dramatically affect plant species during the growing season (starr et al. 2000; bokhorst et al. 2008). previous studies from other regions in the arctic indicate that plants at our sites will likely shift from being temperature-limited to being more nutrient and competition-limited (chapin & shaver 1985b; dormann & woodin 2002). beyond seasonal weather, nutrient availability, and competition, we recognize that many arctic ecotypes are likely to face limitations brought on by genetic constraints making them less able to respond to what would otherwise be considered more favourable growing conditions (starr et al. 2000; mazer et al. 2013). future studies across a greater range of time, latitudes and experimental treatments would help establish the relative importance each of these biotic and abiotic factors has on plant species, ultimately improving our ability to predict and understand the impacts of climate change in tundra ecosystems. the response of plants documented here has complex implications for energy balance, community compositions and trophic interactions. for example, as plants grow taller and increase canopy complexity they absorb more energy, which will further accelerate warming (chapin et al. 2000). however, increasing canopy complexity may also enhance the insulating effect of the vegetation layer, in some cases cooling soils, and may stabilize permafrost (hollister et al. 2008). changes in plant species composition will subsequently influence decomposition rates, in turn affecting carbon and nutrient cycling (aerts 2006). changes in plant phenology, growth and community compositions will affect quality and availability of food for herbivores and pollinators, a phenomenon that has already been documented in some parts of the arctic (post & forchhammer 2008; gilg et al. 2009; gauthier et al. 2013). future work to link the results of studies on the traits of individual species to shifts in community composition will prove highly useful in better forecasting and understanding changes in the arctic due to climate change. acknowledgements we are greatly indebted to the efforts of pat webber, christian bay, craig tweedie and steve oberbauer. we thank the many field assistants who aided in collecting these data, especially j. may, j. liebig, k. kremers and t. botting. we also thank the national science foundation office of polar programs (opp #9714103, #0632263, #0856516 and #1432277) for support, the barrow arctic science consortium and umiaq llc for logistics, the itex network for collaborations and anonymous reviewers for their suggestions. all data are archived and available at advanced cooperative arctic data and information service managed by the national snow and iced data center (www.nsidc.org/acadis/). references aerts r. 2006. the freezer defrosting: global warming and litter decomposition rates in cold biomes. journal of ecology 94, 713�724. arft a.m., walker m.d., gurevitch j., alatalo j.m., bret-harte m.s., dale m.r.t., diemer m.c., gugerli f., henry g.h.r., jones m.h., hollister r.d., jónsdóttir i.s., laine k., lévesque e., marion g.m., molau u., mølgaard p., nordenhall u., raszhivin v., robinson c.h., starr g., stenström a., stenström m., totland ø., turner p.l., walker l.j., webber p.j., welker j.m. & wookey p.a. 1999. responses of tundra plants to experimental warming: meta-analysis of the international tundra experiment. ecological monographs 64, 491�511. bennington c.c., fetcher n., vavrek m.c., shaver g.r., cummings k.j. & mcgraw j.b. 2012. home site advantage in two long-lived arctic plant species: results from two 30-year reciprocal transplant studies. journal of ecology 100, 841�851. billings w.d. & mooney h.a. 1968. the ecology of arctic and alpine plants. biological review 43, 481�529. bliss l.c. 1971. arctic and alpine plant life cycles. annual review of ecology and systematics 2, 405�438. boelman n.t., stieglitz m., rueth h.m., sommerkorn m., griffin k.l., shaver g.r. & gamon j.a. 2003. response of ndvi, biomass, and ecosystem gas exchange to long-term warming and fertilization in wet sedge tundra. oecologia 135, 414�421. bokhorst s., bjerke j.w., bowles f.w., melillo j., callaghan t.v. & phoenix g.k. 2008. impacts of extreme winter warming in the sub-arctic: growing season responses of dwarf shrub heathland. global change biology 14, 2603�2612. campioli m., schmidt n.m., albert k.r., leblans n., ro-poulsen h. & michelsen a. 2013. does warming affect growth rate and biomass production of shrubs in the high arctic? plant ecology 214, 1049�1058. chapin f.s. iii & chapin m.c. 1981. ecotypic differentiation of growth processes in carex aquatilis along latitudinal and local gradients. ecology 62, 1000�1009. r.t. barrett & r.d. hollister arctic plant responses to long-term warming citation: polar research 2016, 35, 25405, http://dx.doi.org/10.3402/polar.v35.25405 7 (page number not for citation purpose) http://www.nsidc.org/acadis/ http://www.polarresearch.net/index.php/polar/article/view/25405 http://dx.doi.org/10.3402/polar.v35.25405 chapin f.s. iii, mcguire a.d., randerson j., pielke r., baldocchi d., hobbie s.e., roulet n., eugster w., kasischke e., rastetter e.b., zimov s.a. & running s.w. 2000. arctic and boreal ecosystems of western north america as components of the climate system. global change biology 6, 211�223. chapin f.s. iii & shaver g.r. 1985a. arctic. in b.f. chabot & h.a. mooney (eds.): physiological ecology of north american plant communities. pp. 16�40. new york: chapman and hall. chapin f.s. iii & shaver g.r. 1985b. individualistic growth response of tundra plant species to environmental manipulations in the field. ecology 66, 564�576. chapin f.s. iii, shaver g.r., giblin a.e., nadelhoffer k.j. & laundre j.a. 1995. response of arctic tundra to experimental and observed changes in climate. ecology 76, 696� 711. chapin f.s. iii, sturm m., serreze m.c., mcfadden j.p., key j.r., lloyd a.h., mcguire a.d., rupp t.s., lynch a.h., schimel j.p., beringer j., chapman w.l., epstein h.e., euskirchen e.s., hinzman l.d., jia g., ping c.l., tape k.d., thompson c.d.c., walker d.a. & welker j.m. 2005. role of land-surface changes in arctic summer warming. science 310, 657�660. dorji t., totland ø., moe s.r., hopping k.a., pan j.b. & klein j.a. 2013. plant functional traits mediate reproductive phenology and success in response to experimental warming and snow addition in tibet. global change biology 19, 459�472. dormann c.f. & woodin s.j. 2002. climate change in the arctic: using plant functional types in a meta-analysis of field experiments. functional ecology 16, 4�17. dunne j.a., harte j. & taylor k.j. 2003. subalpine meadow flowering phenology responses to climate change: integrating experimental and gradient methods. ecological monographs 73, 69�86. elmendorf s.c., henry g.h.r., hollister r.d., bjork r.g., bjorkman a.d., callaghan t.v., collier l.s., cooper e.j., cornelissen j.h.c., day t.a., fosaa a.m., gould w.a., grétarsdóttir j., harte j., hermanutz l., hik d.s., hofgaard a., jarrad f., jónsdóttir i.s., keuper f., klanderud k., klein j.a., koh s., kudo g., lang s.i., loewen v., may j.l., mercado j., michelsen a., molau u., myers-smith i.h., oberbauer s.f., pieper s., post e., rixen c., robinson c.h., schmidt n.m., shaver g.r., stenström a., tolvanen a., totland ø., troxler t., wahren c.h., webber p.j., welker j.m. & wookey p.a. 2012. global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time. ecology letters 15, 164�175. gauthier g., bety j., cadieux m.c., legagneux p., doiron m., chevallier c., lai s., tarroux a. & berteaux d. 2013. longterm monitoring at multiple trophic levels suggests heterogeneity in responses to climate change in the canadian arctic tundra. philosophical transactions of the royal society b 368, article no. 20120482, doi: http://dx.doi.org/10.1098/ rstb.2012.0482 gilg o., sittler b. & hanski i. 2009. climate change and cyclic predator�prey population dynamics in the high arctic. global change biology 15, 2634�2652. gugerli f. & bauert m.r. 2001. growth and reproduction of polygonum viviparum show weak responses to experimentally increased temperature at a swiss alpine site. botanica helvetica 111, 169�180. hedenås h., carlsson b.å., emanuelsson u., headley a.d., jonasson c., svensson b.m. & callaghan t.v. 2012. changes versus homeostasis in alpine and sub-alpine vegetation over three decades in the sub-arctic. ambio 41, 187�196. hollister r.d. 2003. response of tundra vegetation to temperature: implications for forecasting vegetation change. phd thesis, michigan state university. hollister r.d., webber p.j. & bay c. 2005. plant response to temperature in northern alaska: implications for predicting vegetation change. ecology 86, 1562�1570. hollister r.d., webber p.j., nelson f.e. & tweedie c.e. 2006. soil thaw and temperature response to air warming varies by plant community: results from an open-top chamber experiment in northern alaska. arctic antarctic and alpine research 38, 206�215. hollister r.d., webber p.j., slider r.t., nelson f.e. & tweedie c.e. 2008. soil temperature and thaw response to manipulated air temperature and plant cover at barrow and atqasuk, alaska. in d.l. kane & k.m. hinkel (eds.): ninth international conference on permafrost. vol. 2. pp. 729�734. fairbanks: institute of northern engineering. hollister r.d., webber p.j. & tweedie c.e. 2005. the response of alaskan arctic tundra to experimental warming: differences between shortand long-term responses. global change biology 11, 525�536. hudson j.m.g. & henry g.h.r. 2009. increased plant biomass in a high arctic heath community from 1981 to 2008. ecology 90, 2657�2663. hudson j.m.g., henry g.h.r. & cornwell w.k. 2011. taller and larger: shifts in arctic tundra leaf traits after 16 years of experimental warming. global change biology 17, 1013�1021. iler a.m. & inouye d.w. 2013. effects of climate change on mast-flowering cues in a clonal montane herb, veratrum tenuipetalum (melanthiaceae). american journal of botany 100, 519�525. klady r.a., henry g.h.r. & lemay v. 2011. changes in high arctic tundra plant reproduction in response to long-term experimental warming. global change biology 17, 1611� 1624. lambrecht s.c., loik m.e., inouye d.w. & harte j. 2007. reproductive and physiological responses to simulated climate warming for four subalpine species. new phytologist 173, 121�134. mazer s.j., travers s.e., cook b.i., davies t.j., bolmgren k., kraft n.j.b., salamin n. & inouye d.w. 2013. flowering date of taxonomic families predicts phenological sensitivity to temperature: implications for forecasting the effects of climate change on unstudied taxa. american journal of botany 100, 1381�1397. arctic plant responses to long-term warming r.t. barrett & r.d. hollister 8 (page number not for citation purpose) citation: polar research 2016, 35, 25405, http://dx.doi.org/10.3402/polar.v35.25405 http://dx.doi.org/10.1098/rstb.2012.0482 http://dx.doi.org/10.1098/rstb.2012.0482 http://www.polarresearch.net/index.php/polar/article/view/25405 http://dx.doi.org/10.3402/polar.v35.25405 michelsen a., rinnan r. & jonasson s. 2012. two decades of experimental manipulations of heaths and forest understory in the subarctic. ambio 41, 218�230. molau u. (ed.) 1993. international tundra experiment (itex) manual. copenhagen: danish polar center. natali s.m., schuur e.a.g. & rubin r.l. 2012. increased plant productivity in alaskan tundra as a result of experimental warming of soil and permafrost. journal of ecology 100, 488�498. oberbauer s.f., elmendorf s.c., troxler t.g., hollister r.d., rocha a.v., bret-harte m.s., dawes m.a., fosaa a.m., henry g.h.r., høye t.t., jarrad f.c., jónsdóttir i.s., klanderud k., klein j.a., molau u., rixen c., schmidt n.m., shaver g.r., slider r.t., totland ø., wahren c.-h. & welker j.m. 2013. phenological response of tundra plants to background climate variation tested using the international tundra experiment. philosophical transactions of the royal society b 368, 1�13. oberbauer s.f., tweedie c.e., welker j.m., fahnestock j.t., henry g.h.r., webber p.j., hollister r.d., walker m.d., kuchy a., elmore e. & starr g. 2007. tundra co2 fluxes in response to experimental warming across latitudinal and moisture gradients. ecological monographs 77, 221�238. post e. & forchhammer m.c. 2008. climate change reduces reproductive success of an arctic herbivore through trophic mismatch. philosophical transactions of the royal society b 363, 2369�2375. post e., pedersen c., wilmers c.c. & forchhammer m.c. 2008. warming, plant phenology and the spatial dimension of trophic mismatch for large herbivores. proceedings of the royal society b 275, 2005�2013. r development core team 2005. r: a language and environment for statistical computing. vienna: r foundation for statistical computing. rosenberg m.s., adams d.c. & gurevitch j. 2000. metawin: statistical software for meta-analysis with resampling tests. version 2.0. sunderland, ma: sinauer associates. shaver g.r. & jonasson s. 1999. response of arctic ecosystems to climate change: results of long-term field experiments in sweden and alaska. polar research 18, 245�252. shaver g.r. & kummerow j. 1992. phenology, resource allocation, and growth of arctic vascular plants. in f.s. chapin iii et al. (eds.): arctic ecosystems in a changing climate an ecophysiological perspective. pp. 193�211. san diego, ca: academic press. starr g., oberbauer s.f. & pop e.w. 2000. effects of lengthened growing season and soil warming on the phenology and physiology of polygonum bistorta. global change biology 6, 357�369. stocker t.f., qin d., plattner g.-k., tignor m., allen s.k., boschung j., nauels a., xia y., bex v. & midgley p.m. (eds.) 2013. climate change 2013. the physical science basis. contribution of working group i to the fifth assessment report of the intergovernmental panel on climate change. cambridge: cambridge university press. symon c., arris l & heal b. (eds.) 2005. arctic climate impact assessment. cambridge: cambridge university press. thórhallsdóttir t.e. 1998. flowering phenology in the central highland of iceland and implications for climatic warming in the arctic. oecologia 114, 43�49. r.t. barrett & r.d. hollister arctic plant responses to long-term warming citation: polar research 2016, 35, 25405, http://dx.doi.org/10.3402/polar.v35.25405 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/25405 http://dx.doi.org/10.3402/polar.v35.25405 variability of biothermal conditions in the vicinity of the polish antarctic station in the south shetlands, west antarctica research article variability of biothermal conditions in the vicinity of the polish antarctic station in the south shetlands, west antarctica joanna plenzler1, katarzyna piotrowicz2, weronika rymer3 & tomasz budzik4 1institute of biochemistry and biophysics, polish academy of sciences, warsaw, poland; 2institute of geography and spatial management, jagiellonian university, krakow, poland; 3faculty of medicine, university of opole, opole, poland; 4institute of earth sciences, university of silesia in katowice, katowice, poland abstract there are nine year-round and 11 seasonal scientific stations in the south shetland islands, an area often visited by cruise ships and sailing yachts. although this is the warmest part of antarctica, the weather conditions may be demanding for humans. we analysed the variability of biothermal conditions near henryk arctowski station polish antarctic station, on king george island, during the period 2013–2021, using the wind chill index (wci), which combines air temperature and wind speed, to determine thermal sensation. wci values were interpreted using two cold sensation categorisations. hourly wci values were assigned to thermal sensation classes that ranged from “comfortable” to “frosty.” the most favourable biothermal conditions occurred from december to february. the “cold” sensation was dominant in all months, its average occurrence frequency ranging from 56.4% (in january) to 84.4% (in july). from november to march, there was no risk of frostbite to uncovered body parts. such conditions occurred only from april to october, with a frequency of 0.2–6.8%; biothermal conditions were also the most variable in this period. maximal wci hourly values show that dangerous weather conditions may occur throughout the day in june and for most of the day from july to september. an abrupt change in biothermal conditions was more often caused by wind speed change than by air temperature change. the most marked wci changes occurred from april to september, on average five times per year. our results indicate that biothermal conditions in the vicinity of arctowski station are predominantly favourable for outdoor work only if a person wears proper winter clothing. keywords bioclimate; work environment; work hazards; polar occupational medicine; wind chill index; frostbite abbreviation: wci: wind chill index   citation: polar research 2023, 42, 9108, http://dx.doi.org/10.33265/polar.v42.9108 copyright: © 2023 joanna plenzler et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published 22 august 2023 competing interests and funding: the authors declare no conflicts of interest. the research was funded by institute of biochemistry and biophysics, polish academy of sciences. correspondence: joanna plenzler, institute of biochemistry and biophysics, polish academy of sciences, ul. a. pawińskiego 5a, 02-106 warsaw, poland. e-mail: joannapl@ibb.waw.pl   introduction the south shetland islands are the most densely populated part of antarctica. there are nine year-round and 11 seasonal scientific stations (secretariat of the antarctic treaty 2019). stations workers, especially during the summer season, from december to march, spend a lot of time outdoors carrying out scientific and technical tasks. the south shetland islands and antarctic peninsula are also the part of antarctica that receives the most visits by cruise ships and sailing yachts (secretariat of the antarctic treaty 2020). this is the warmest part of antarctica, but the weather conditions may be demanding, so information about biometeorological conditions and their variability during the year can be useful for those planning to work there. investigations concerning biometeorological conditions and their impact on humans in the polar regions have been conducted for a long time, especially in the arctic, which is populated by indigenous and non-indigenous people, including personnel at scientific stations and other seasonal workers (e.g., eagan 1966; mäkinen et al. 2006; mäkinen 2007; araźny 2008; araźny et al. 2010; brozovsky et al. 2021). several methods and indexes have been developed for describing and assessing the biometeorological conditions in the polar regions (e.g., siple & passel 1945; kozłowska-szczęsna et al. 1997; maarouf & bitzos 2001; uk hydrographic office 2004). in the case of antarctica, where humans have been present for only 200 years, biometeorological research has concerned the influence of the antarctic environment conditions and long-term isolation on various aspects of human health, such as physical performance (e.g., simpson & maynard 2012), cold acclimatisation (e.g., budd 1962; bodey 1978; naidu & sachdeva 1993), sleep quality (e.g., bhattacharyya et al. 2008), hormonal balance (e.g., sawhney et al. 1998; chengli et al. 2003; chen et al. 2016), mental health (e.g., chen et al. 2016; kuwabara et al. 2021) and other health-related issues (e.g., belkin & karasik 2001; otani et al. 2004; bhatia et al. 2013; ikeda et al. 2019). this research has focused on the effects of environmental conditions rather than on the conditions themselves, as discussed by wilson (1967) and lu et al. (2015). biometeorological research hitherto conducted in the vicinity of the henryk arctowski polish antarctic station (hereafter arctowski station) presented results for the summer season (december–march) in the period 1977– 1990 (gregorczuk 1977; styszyńska 1989, 1994) and for the whole year in the period 2015–19 (węglowska 2021). wind chill during the whole year was discussed by styszyńska (2000), on the basis of data from the period 1978–1998. consistent with the general observations of expedition members, these works concluded that biometeorological conditions were predominantly safe for a suitably dressed person. however, rapid wind speed changes could suddenly bring on conditions that may lead to frostbite or hypothermia for people not properly dressed or far from a shelter (styszyńska 2000). an abrupt change in weather conditions creates an additional threat for those working at the sea. this underlined the need for better knowledge of the frequency and intensity of changes in biometeorological conditions. the research reported herein investigated the variability of biothermal conditions in the vicinity of arctowski station, on king george island, in the south shetland islands, using the wci. particular attention was paid to the frequency of rapid wci value changes, its multi-annual variability and the frequency of safe and dangerous conditions. methods and research area the south shetland islands, the warmest part of antarctica, lie approximately 120 km north of the antarctic peninsula, in the subantarctic maritime climate zone (marsz & styszyńska 2000). the climate in this region is mostly determined by the sea-surface temperature and the extent, concentration and distribution of sea ice (marsz & styszyńska 2000; kejna et al. 2013; turner et al. 2013). the air-pressure lows that often pass through the region also play an important role (simmonds et al. 2003). together, these factors create meteorological conditions that vary greatly from year to year (marsz & styszyńska 2000; turner et al. 2013). the region is also experiencing some of the most significant climate warming in the world (bromwich et al. 2013; gonzalez & fortuny 2018; gonzalez-herrero et al. 2022). the analysis of biothermal conditions may also be interesting in this context. the research was based on data collected by an automatic weather station located close to arctowski station, on the western shore of admiralty bay, king george island. more than 90% of the island is covered by glacier caps that have an elevation of up to 700 m a.s.l. (rückamp & blindow 2012). the weather station is located on a low sea terrace 2 m a.s.l., 150 m from the main station’s building and 100 m from the coast (fig. 1). air temperature and wind speed from the period 2013–2021, measured every hour, were used in the research. air temperature is measured by a vaisala hmp155 sensor installed at 2 m above ground. the accuracy of the measurements is ±0.2°c. wind speed is measured at 2.5 m. from january 2013 to january 2017, it was measured by a gill wind sonic sensor (accuracy ±0.2% at 12 m/s) and from january 2013 to february 2017 to december 2021 by a vector instrument a100r mechanic sensor (accuracy ±0.1 m/s at 0–10 m/s; 1% at 10–55 m/s; 2% above 55 m/s). mean multi-annual (2013–2021) air temperature at arctowski station was -1.3°c. the coldest month was august (mean multi-annual monthly air temperature -5.6°c) and february the warmest (2.0°c; fig. 2). the highest hourly temperature values were about 5°c in june–september and about 10°c in the remaining months. the lowest values ranged from -3.1°c in january to -22.1°c in july. the mean annual wind speed was 5.6 m/s, but the maximum records reached up to 32 m/s (115 km/hr; fig. 2). all times given are local time, which is zone utc-3. fig. 1 location of the study area and landscape in the vicinity of arctowski station during summer and winter. (photos: p. andryszczak & j. plenzler.) fig. 2 variability of (a) hourly air temperature and (b) wind speed for each month at arctowski station (2013–2021). wci was used to determine thermal sensation. invented by p.a. siple and c. passel during investigations in antarctica in the first half of the 20th century, the index represents the rate of heat loss from the unprotected surface of the skin. as modified by court (1948), the formula for determining wci (in w/m2) is as follows: wci = (10.9*√v+9.0-v)*(33.0-t)*1.163, where v is wind speed (m/s) and t is air temperature (°c). wci was chosen for our study because it is used for weather conditions with low air temperature and has been used many times in bioclimatological analyses of polar regions (kozłowska-szczęsna et al. 1997). determining the real rate of heat loss by a human exposed to low temperature and wind is complex and demands taking account of such individual factors as body heat production, fat tissue and clothing. siple and passel’s wci formula (modified by court) was chosen for this study because it involves only environmental measurements, with no need to consider physiological aspects of heat loss and individual characteristics (shitzer 2006; lankford & fox 2021). the mean wci values in individual months and years that we present were calculated on the basis of hourly values. hourly values were classified according to the thermal sensations experienced by a person wearing winter clothing with a level of thermo-insulation at 4.0 clo (kent 2006): heavy other clothing, including thermo-insulative underwear, woollen sweater, heavy coat, cap, gloves and boots (holmér 1988; kozłowska-szcezęsna et al. 1997; maarouf & bitzos 2001; table 1). according to this classification, referred to as the “thermal sensation” system herein, when wci is higher than 1628.2 w/m2, corresponding to the sensations “frosty” and “extremely frosty,” there is a risk of frostbite to uncovered parts of the body, even when they are only briefly exposed to the cold. when wci is higher than 2326 w/m2 frostbite of uncovered parts of the body occurs after just 30 seconds and staying inside is recommended (maarouf & bitzos 2001). table 1 thermal sensations of a human dressed in heavy outer clothing corresponding to the range of wci values (kozłowska-szczęsna et al. 1997; maarouf & bitzos 2001). asterisks mark categories that were found to have occurred during the study reported here. wci (w/m2) thermal sensation <58.3 extremely hot 58.3–116.3 hot 116.4–232.6 warm 232.7–581.5 comfortable* 581.6–930.4 cool* 930.5–1628.2 cold* 1628.3–2325.9 frosty* ≥2326.0 extremely frosty another classification system, which is applied to operations in the polar regions, assigns wci values to seven categories of cooling—numbered from i (mildest) to vii (coldest)—and includes recommendations for how to behave in particular conditions (marsz & styszyńska 2000; uk hydrographic office 2004; table 2). according to this classification system, referred to herein as the “cooling category” system, the most favourable conditions are when wci is below 930 w/m2. table 2 characteristics of each cooling category according to wci values (uk hydrographic office 2004: 177). asterisks mark categories that were found to have occurred during the study reported here. category wci (w/m2) characteristics of the category i* < 930 comfortable with normal precautions. ii* 930–1394 work becomes uncomfortable on overcast days unless properly clothed. iii* 1395–1626 work becomes more hazardous even on clear days unless properly clothed. heavy outer clothing is necessary. iv* 1627–1859 unprotected skin will freeze with direct exposure over a prolonged period, depending on degree of activity, amount of solar radiation and state of skin and circulation. heavy outer clothing becomes mandatory. v* 1860–1975 unprotected skin can freeze in 1 min with direct exposure. multiple layers of clothing are mandatory. adequate face protection becomes important. work alone is not advisable. vi* 1976–2091 adequate face protection becomes mandatory. work alone must be prohibited and supervisors must control exposure time by careful scheduling. vii >2091 survival efforts are required. personnel become easily fatigued, and mutual observations of companions is mandatory. results during 2013–2021, the mean hourly wci values for each month were from 853.9 w/m2 (january 2020) to 1327.0 w/m2 (august 2020). these values correspond predominantly to the “cold” thermal sensation (see table 1); only in january 2018 and 2020 did the “cool” sensation prevail (fig. 3). fig. 3 variability of (a) mean monthly and (b) actual hourly wci values (w/m2) at arctowski station (2013–2021). the dashed lines show the limits of the cooling category (see table 2 for explanations). the highest mean annual value (1116.1 w/m2) occurred in 2015, which was the coldest year of the analysed period (fig. 3). the lowest (1057.4 w/m2) was in 2020, a relatively warm and windy year (fig. 3). the most favourable biothermal conditions were in january, february and december. in those months, mean hourly wci values were usually lower than 1000 w/m2, but in individual hours, they exceeded 1400 w/m2, that is, cooling category iii (see table 2). in the winter season (may–october), mean wci values were predominantly higher than 1100 w/m2, with a maximum in june and august (2000–14 w/m2; fig. 3). hourly wci values during the investigated period fell into thermal sensation classes ranging from “comfortable” to “frosty” (fig. 4). in all months, the thermal sensation “cold” was dominant; its average occurrence frequency was from 56.4% in january to 84.4% in july. during the summer months, especially in january, “cool” conditions occurred often (up to 42.8%). from november to march, there were no “frosty” conditions, which means that there was no risk of frostbite to uncovered body parts. conditions carrying a risk of frostbite occurred from april to october with a frequency of 0.2–6.8% (fig. 4). it is important to note that even during the winter season there were single hours that a properly clothed person (clo 4.0) would sense as “comfortable.” those were the hours with positive air temperature and wind speed lower than 0.4 m/s; their frequency was <0.1% in july and september and 1.1% in february (fig. 4). fig. 4 thermal sensation frequency (%) according to wci hourly values at arctowski station (2013–2021). some other conclusions can be assumed from analyses of the cooling categories (table 2). during the analysed nine years, only cooling category vii (requiring survival efforts) did not occur. category vi occurred in only a single hour in june, august and september, and it constituted only 0.2% of all wci hourly cases in the year. in this category, face protection becomes mandatory, and it is forbidden to work alone outside. the most frequent was category ii (work becomes uncomfortable on overcast days unless the person is properly clothed), which constituted more than 55% of all wci hourly cases in the year (table 3). during each month, 12.4 to 43.5% of the wci hourly values were in cooling category i: work outside was comfortable for a properly clothed person. table 3 the frequencies of cooling categories (%) according to wci hourly values at arctowski station (2013–2021). category jan feb mar apr may jun jul aug sep oct nov dec year i 43.5 39.7 34.5 21.0 19.6 17.6 12.4 13.5 13.6 16.9 24.1 33.9 24.0 ii 56.5 59.8 64.0 74.2 70.4 67.8 74.4 63.5 71.7 77.5 74.5 66.0 68.4 iii 0.0 0.5 1.4 3.7 9.1 11.5 10.1 16.1 10.6 5.4 1.4 0.1 5.9 iv 1.1 0.8 2.5 2.9 6.2 3.7 0.2 1.5 v 0.4 0.3 0.5 0.4 0.1 vi 0.1 0.1 0.0 0.0 minimal wci hourly values in particular months (fig. 5) show that in the middle of winter (july) “comfortable” thermal sensation conditions occurred only at 06:00, 20:00 and 23:00 and in september only at 15:00 and 18:00. from december to february, “comfortable” thermal sensation conditions occurred almost every hour. all minimum values were in cooling category i. mean wci values calculated for each hour, separately for each month during the analysed multi-year period (for example, the mean wci at 06:00 throughout the month of january across all years in the investigated period), all fell within cooling category iii, which corresponds to the “cold” thermal sensation. work under such conditions becomes more hazardous even on clear days unless one is properly clothed. maximal wci hourly values show that dangerous weather conditions (cooling categories v and vi) may occur throughout the day in june and for most of the day from july to september (fig. 5). unprotected skin can freeze in 1 minute with direct exposure. work alone then is not advisable and should even be prohibited (table 2). in december and january, and during several hours in november and february, temperature and wind speed were favourable to milder conditions (cooling category ii), when even the maximum wci values did not exceed 1394 w/m2. fig. 5 (a) minimal and (b) maximal wci values (w/m2) for particular hours during each month at arctowski station (2013–2021). the corresponding cooling categories and thermal sensations are indicated. in order to describe and better understand biothermal conditions in the vicinity of arctowski station, particular attention was paid to the daily course of wci values (fig. 6) and changes of its hourly values from one hour to the next one (hereafter hour-to-hour changes; table 4). the most dangerous cooling category—vi—occurred in the analysed period in 2013, 2017 and 2021 and was caused by air temperatures below -16.0°c and wind speeds above 10.0 m/s. such conditions were recorded at various parts of the day, for example at 03:00, 06:00, 09:00 and 15:00 (fig. 6). conditions that create a threat of freezing of unprotected skin within 1 minute (cooling category v) must be considered in the period from june to september, throughout the day. opportunities for safely working outdoors may be limited by the risk of freezing of unprotected skin if it is exposed over a prolonged period (cooling category iv) from april to october, especially from 12:00 to 15:00, when the frequency of such conditions was up to 7.2% (fig. 6). from november to march, the frequency of weather conditions during which work becomes dangerous if the appropriate clothing is not worn (cooling category iii) was low during almost all hours of the day. as mentioned above, cooling categories i and ii were the most frequent during each month and each part of the day. the share of these categories was a little bit higher between 9:00 and 18:00 than between 21:00 and 06:00 (fig. 6). table 4 frequency of hour-to-hour cooling category changes at arctowski station (2013–2021). cases without change (78.3%) were not included. category change from hour to hour jan-dec apr-sep oct-mar i–ii 40.2 33.2 47.7 i–iii 0.1 0.2 0.0 ii–i 40.2 33.3 47.7 ii–iii 7.3 11.9 2.2 ii–iv 0.2 0.3 – iii–i 0.1 0.2 0.0 iii–ii 7.3 12.0 2.2 iii–iv 1.9 3.6 0.1 iii–v 0.0 0.0 – iv–i 0.0 0.0 – iv–ii 0.1 0.2 – iv–iii 2.0 3.7 0.1 iv–v 0.3 0.5 – iv–vi 0.0 0.0 – v–iii 0.0 0.0 – v–iv 0.3 0.6 – v–vi 0.0 0.1 – vi–iv 0.0 0.0 – vi–v 0.0 0.1 – fig. 6 cooling categories frequency (%) according to wci hourly values at arctowski station (2013–2021). situations when weather conditions—and biothermal sensations—become abruptly more severe may be dangerous. the analysis of hour-to-hour changes was conducted for the whole year and for summer (october–march) and winter (april–september) half-years (table 4). cases when there was no change—78.3% of cases—were not included. the most frequent were the changes between cooling categories i and ii (table 4). such cases constituted 80.4% of all change cases during the year and 95.4% during the summer half-year. during the summer half-year, two-category jumps occurred intermittently and were comprised of rapid changes between cooling categories i and iii; these were less than 0.1% of all hour-to-hour changes from october to march. the most biting changes from cooling category i to category iii occurred in october 2015 and 2020 (at 07:00–08:00 and 23:00–24:00), while changes from cooling category iii to i occurred in october 2015 and 2017 (at 08:00–09:00 and 04:00–05:00). they were chiefly caused by an abrupt increase or decrease in wind speed (from 1 to 10 m/s or conversely) at a stable air temperature of circa -4.0°c. during the winter half-year (april–september) changes in biothermal conditions occurred very abruptly. hour-to-hour changes by two cooling categories constituted 1% of cases (table 4). they occurred most frequently in august and september, almost half of them (47.0%) between 09:00 and 18:00, the hours of the highest fieldwork activity. during the investigated nine-year period, the most intense wci changes occurred from april to september: shifts from cooling category i to iii occurred on average twice per year; and changes from ii to iv occurred two to three times per year. changes from cooling category iii to v (in september) and iv to vi (august–september) occurred sporadically: once in three years, in august or september (fig. 7). an abrupt decrement from cooling category iii to i (may–october) and from iv to i (july–september) occurred on average once or twice a year. changes from iv to i and from v to iii were recorded only two or three times during the investigated period and a change from vi to iv only once, in september 2013. fig. 7 examples of the daily course of air temperature (°c), wind speed (m/s) and cooling categories, with wci values, at arctowski station. abrupt shifts in biothermal conditions were more often caused by changes in wind speed rather than air temperature change. the largest recorded hour-to-hour changes were drops by three cooling categories, from iv to i, which occurred at 06:00–07:00 in july 2017 and at 08:00–09:00 august 2013 (fig. 7). discussion although people have dwelled in northern circumpolar areas for millennia, the human body has only a slight physiological ability to adapt to a cold environment. the most important health issues related to stays in the polar regions are hypothermia, frostbite, non-freezing cold injury (e.g., trench foot/immersion foot, chilblains/pernio, frostnip), sunburns and snow-blindness. falling into cold water may bring on a cold shock response, cardiac arrest through bradycardia or arrhythmia; injuries may result from exposure to icy surfaces (long et al. 2005; rathjen et al. 2019; nyssen et al. 2020; zafren 2021). discomfort caused by prolonged exposure to the cold may also affect aspects of mental performance, such as concentration, and may therefore heighten the risk of work accidents (palinkas 2001). additionally, there are very high energetic costs incurred when the body produces more heat to offset a cold environment and in bearing the weight of clothing that is a necessary protection. it is assumed that each additional kilogramme of clothing increases the energy costs of the body by 3% (mäkinen & hassi 2009). exposure to cold can also exacerbate chronic disease (rathjen et al. 2019). this paper focused on air temperature and wind speed. low temperature is the main cause of hypothermia and frostbite, but wind speed enhances the cooling of a body and is responsible for thermal sensation. the higher the wind speed, the greater the heat loss, leading to the perception of a lower temperature than indicated on a weather thermometer. there are 10 scientific stations on king george island, three of which are in the neighbourhood of arctowski station: the year-round comandante ferazz antarctic station (brazil) and the summer stations copacabana (us) and machu picchu scientific base (peru) (fig. 1). arctowski station is a year-round station where 8–11 people are employed on whole-year contracts and up to 30 more people work during the summer. fieldwork is conducted on land and glaciers and at sea. technical work, such as maintaining the station’s building, also entails working outside. motorboats are very often used as transport. during the summer season field excursions are undertaken almost every day. over a dozen people are working outdoors for one to circa 16 hours, from the early morning (04:00) to late evening (22:00). during winter, the time spent outdoors is shorter (circa 6–8 hours), proportionate to the hours of daylight. even though outside work is avoided during very challenging weather conditions (especially strong wind), it may sometimes be necessary even in such conditions to make outdoor repairs or to transfer between station buildings. therefore, 24-hour wci values were analysed in this paper. the tourist season in west antarctica lasts from the beginning of december to the end of february, the period with the most favourable biothermal conditions. between the years 2008 and 2018, arctowski station was visited by 500 to 7000 tourists per season (wilkońska et al. 2020). a relatively large proportion of cruise ship passengers are elderly people: 42% percent of respondents in a study by wilkońska et al. (2020) were 60 or more years old. such persons often suffer from chronic illnesses and may experience relatively high discomfort because of cold and wind or abrupt changes in weather conditions; however, these are very individual characteristics. the mean monthly and annual wci values (2013–2021) that we have presented here are lower than those obtained by styszyńska (2000) on the basis of a 1977–1998 data series. this difference is not because of styszyńska having used an older version of the wci formula than we used: the formula applied in our research usually results in higher values than those calculated using the older one. during the period 1977–1998, the range of mean monthly wci values was from 915.1 w/m2 (january 1990) to 1532.3 w/m2 (july 1982), and mean monthly wci values in july were classified as belonging to cooling category iii six times, while there were no such cases during 2013–2021 (fig 3). this indicates that biothermal conditions were slightly milder during 2013–2021 than 1977–1998. this may be a result of climate warming observed in the region, which, among other things, had lower absolute minimal temperatures in 1977–1998 than in 2013–17 (plenzler et al. 2019). mean monthly and annual wci values (2013–2021) at arctowski station are similar to wci values presented by araźny (2008) for svalbard (1971–2000), particularly for meteorological stations at ny-ålesund, svalbard airport, hornsund, hopen and bjørnøya. however, at those stations, multi-annual monthly wci values of summer months were classified, according to the thermal sensation categories, as “cool,” whereas at arctowski station they were “cold.” that indicates slightly cooler summer conditions at arctowski station comparing to svalbard. in the case of mean daily wci values in south-west spitsbergen, the thermal sensations “cool” and “cold” were dominant, similar to arctowski station (araźny 2008; sikora et al. 2010; sikora et al. 2011). an important limitation of our study is that it was based on measurements from a weather station located at sea level, so the results apply only to the low-lying parts of the island. at its highest point, the ice cap is about 700 m a.s.l., and the air temperature is lower there: the temperature gradient is 0.6°c /100 m (kejna 2008). consequently, biometeorological conditions are expected to be more severe at high altitudes on the island and to investigate them it would be advisable to use a more complex index that considers also barometric pressure. wci is calculated on the basis of only air temperature and wind speed. the application of a more complex biothermal index would require surface radiation measurements that were not available for the whole period of 2013–2021. our broad preliminary approach should help determine the most important issues for future investigation. for example, our results from the area around arctowski station, where the temperature is often above 0°c, point towards further research to determine how often conditions occur that could cause non-freezing cold injuries. as the south shetland archipelago is not very large, and the main factors that shape the climate on the individual islands are similar, our results may be generally representative for the whole area. according to bañón et al. (2013), there is a strong correlation between the mean daily air temperature on byers peninsula (western livingston island) and bellingshausen station (russia) on king george island (fig. 1) and between the mean daily air temperature on byers peninsula and deception island (pearson correlation coefficients were 0.97 and 0.93, respectively, confidence 95%). the mean annual air temperature at arctowski during 2013–17 was about 0.5°c higher than at bellingshausen and base presidente eduardo frei montalva (chile) stations and similar to carlini base (argentina; (plenzler et al. 2019). because of its location in the lee of the ice cap, arctowski station usually experiences weaker winds than the other stations on king george island, which are not protected from the prevailing wind, which in this area come from the north-west. biothermal conditions might be slightly milder there, but additional investigation would be needed to confirm this. conclusions the results of this study show that biothermal conditions in the vicinity of arctowski station are mainly favourable for outdoor work if people are wearing heavy winter clothing. this confirms previous scientific research and the observations of people working in this area. during the investigated period, daily biothermal conditions varied within particular years but in every year “cool” and “cold” thermal sensations predominated. biothermal conditions may deteriorate abruptly during any season, but it is during the winter months that such changes pose the greatest threat. people planning a wintertime stay in the area should bear in mind that even though large, abrupt shifts in biothermal conditions occurred very seldom, they did occur in each of the years we investigated. acknowledgements the authors are thankful to the crew of henryk arctowski polish antarctic station for the maintenance of the automatic weather station and to the reviewers for their useful comments that helped to improve the manuscript. references araźny a. 2008. bioklimat arktyki norweskiej i jego zmienność w okresie 1971–2000. (bioclimatic condition and their variability in the norwegian arctic for the period 1971–2000.) toruń, poland: mikołaj kopernik university press. araźny a., migała k., sikora s. & budzik t. 2010. meteorological and biometeorological conditions in the hornsund area (spitsbergen) during the warm season. polish polar research 31, 217–238, doi: 10.2478/v10183−010−0002−4. bañón m., justel a., velázquez d. & quesada a. 2013. regional weather survey on byers peninsula, livingston island, south shetland islands, antarctica. antarctic science 25, 146–156, doi: 10.1017/s0954102012001046. belkin v. & karasik d. 2001. the effect of season. occupation and repeated winterings on anthropologic and physiological characteristics in russian antarctic staff. international journal of circumpolar health 60, 41–51, doi: 10.1080/22423982.2001.12112996. bhatia a., malhotra p. & agarwal a. 2013. reasons for medical consultation among members of the indian scientific expeditions to antarctica. international journal of circumpolar health 72, article no. 20175, doi: 10.3402/ijch.v72i0.20175. bhattacharyya m., pal m.s., sharma y.k. & majumdar d. 2008. changes in sleep patterns during prolonged stays in antarctica. international journal of biometeorology 52, 869–879, doi: 10.1007/s00484-008-0183-2. bodey a.s. 1978. changing cold acclimatization patterns of men living in antarctica. international journal of biometeorology 22, 163–176, doi: 10.1007/bf01555395. bromwich d., nicolas j., monaghan a., lazzara m., keller l., weidner g. & wilson a. 2013. central west antarctica among the most rapidly warming regions on earth. nature geoscience 6, 139–145, doi: 10.1038/ngeo1671. brozovsky j., gaitani n. & gustavsen a. 2021. a systematic review of urban climate research in cold and polar climate regions. renewable & sustainable energy reviews 138, article no. 110551, doi: 10.1016/j.rser.2020.110551. budd g.m. 1962. acclimatization to cold in antarctica as shown by rectal temperature response to a standard cold stress. nature 193, 886, doi: 10.1038/193886a0. chen n., wu q., li h., zhang t. & xu c. 2016. different adaptations of chinese winter-over expeditioners during prolonged antarctic and sub-antarctic residence. international journal of biometeorology 60, 737–747, doi: 10.1007/s00484-015-1069-8. chengli x., guangjin z., quanfu x., shandong z., guoyuan d., yanzhen x. & palinkas l.a. 2003. effect of the antarctic environment on hormone levels and mood of chinese expeditioners. international journal of circumpolar health 62, 255–267, doi: 10.3402/ijch.v62i3.17562. court a. 1948. wind chill. bulletin of the american meteorological society 29, 487–493, doi: 10.1175/1520-0477-29.10.487. eagan j. 1966. biometeorological aspects in the ecology of man in high latitudes. international journal of biometeorology 10, 293–304, doi: 10.1007/bf01426227. gonzalez s. & fortuny d. 2018. how robust are the temperature trends on the antarctic peninsula? antarctic science 30, 322–328, doi: 10.1017/s0954102018000251 gonzalez-herrero s., barriopedro d., trigo r.m. lópez-bustins j.a. & oliva m. 2022. climate warming amplified the 2020 record-breaking heatwave in the antarctic peninsula. communications earth & environment 3, 1–9, doi: 10.1038/s43247-022-00450-5. gregorczuk m. 1977. klimat i bioklimat regionu polskiej stacji antarktycznej im. h. arctowskiego. (climate and bioclimate in the vicinity of arctowski station.) przegląd geofizyczny 22, 231–241. holmér i. 1988. assessment of cold stress in terms of required clothing insulation—ireq. international journal of industrial ergonomics 3, 159–166, doi: 10.1016/0169-8141(88)90017-0. ikeda a., ohno g., otani s., watanabe k. & imura s. 2019. disease and injury statistics of japanese antarctic research expeditions during the wintering period: evaluation of 6837 cases in the 1st–56th parties—antarctic health report in 1956–2016. international journal of circumpolar health 78, article no. 161132, doi: 10.1080/22423982.2019.1611327. kejna m. 2008. topoclimatic conditions in the vicinity of the arctowski station (king george island, antarctica) during the summer season of 2006/2007. polish polar research 29, 95–116. kejna m., araźny a. & sobota i. 2013. climatic change on king george island in the years 1948–2011. polish polar research 34, 213–235. kent m. 2006. the oxford dictionary of sports science and medicine. 3rd edn. oxford: oxford university press. kozłowska-szczęsna t., błażejczyk k. & krawczyk b. 1997. bioklimatologia człowieka. metody i ich zastosowanie w badaniach bioklimatu polski. (human bioclimatology. methods and their application in the study of the bioclimate of poland.) warsaw: polish academy of sciences institute of geography and spatial organization. kuwabara t., naruiwa n., kawabe t., kato n., sasaki a., ikeda a., otani s., imura s., watanabe k. & ohno g. 2021. human change and adaptation in antarctica: psychological research on antarctic wintering-over at syowa station. international journal of circumpolar health 80, article no. 1886704, doi: 10.1080/22423982.2021.1886704. lankford h.v. & fox l.r. 2021. the wind-chill index: lessons from history. wilderness and environmental medicine 32, 392–399, doi: 10.1016/j.wem.2021.04.005. long w.b. 3rd,. edlich r., winters k.l. & britt l.d. 2005. cold injuries. journal of long-term effects of medical implants 15, 67–78, doi: 10.1615/jlongtermeffmedimplants.v15.i1.80. lu y., wang f., wan x., song g., shi w. & zhang c. 2015. clothing resultant thermal insulation determined on a movable thermal manikin. part i: effects of wind and body movement on total insulation. international journal of biometeorology 59, 1475–1486, doi: 10.1007/s00484-015-0958-1. maarouf a. & bitzos m. 2001. les indices de refroidissement éolien: état de la question, applications actuelles et orientations futures pour le canada. (wind chill indices: status, current applications and future directions for canada.) climat et santé 22, 7–37. marsz a.a. & styszyńska a. (eds.) 2000. główne cechy klimatu rejonu polskiej stacji antarktycznej im. h. arctowskiego (antarktyka zachodnia. szetlandy południowe. wyspa króla jerzego). (the main features of the climate region the polish antarctic station h. arctowski [west antarctica, south shetland islands, king george island].) gdynia: gdynia maritime university press. mäkinen t.m. 2007. human cold exposure, adaptation and performance in high latitude environments. american journal of human biology 19, 155–164, doi: 10.1002/ajhb.20627. mäkinen t.m. & hassi j. 2009. health problems in cold work. industrial health 47, 207–220, doi: 10.2486/indhealth.47.207. mäkinen t.m., raatikka v.-p., rytkönen m., jokelainen j., rintamäki h., ruuhela r., näyhä s. & hassi j. 2006. factors affecting outdoor exposure in winter: population-based study. international journal of biometeorology 51, 27–36, doi: 10.1007/s00484-006-0040-0. naidu m. & sachdeva u. 1993. effect of local cooling on skin temperature and blood flow of men in antarctica. international journal of biometeorology 37, 218–221, doi: 10.1007/bf01387527. nyssen a., benhadou f., magnée m., andré j., koopmansch c. & wautrecht j.c. 2020. chilblains. vasa 49, 133–140, doi: 10.1024/0301-1526/a000838. otani s., ohno g., shimoeda n. & mikami h. 2004. morbidity and health survey of wintering members in japanese antarctic research expedition. international journal of circumpolar health 63, 165–168, doi: 10.3402/ijch.v63i0.17890. palinkas l.a. 2001. mental and cognitive performance in the cold. international journal of circumpolar health 60, 430–439, doi: 10.1080/22423982.2001.12113048. plenzler j., budzik t., puczko d. & bialik r.j. 2019. climatic conditions at the h. arctowski polish antarctic station (king george island. antarctica) in 2013–2017 against the background of observed regional changes. polish polar research 40, 1–27, doi: 10.24425/ppr.2019.126345. rathjen n.a., shahbodaghi s.d. & brown j.a. 2019. hypothermia and cold weather injuries. american family physician 100, 680–686. rückamp m. & blindow n. 2012. king george island ice cap geometry updated with airborne gpr measurements. earth system science data 4, 23–30, doi: 10.5194/essd-4-23-2012. sawhney r.c., malhotra a.s., prasad r., pal k., kumar r. & bajaj a.c. 1998. pituitary–gonadal hormones during prolonged residency in antarctica. international journal of biometeorology 42, 51–54, doi: 10.1007/s004840050083. secretariat of the antarctic treaty 2019. antarctica inspected facilities. (map.) accessed on the internet at https://antarctictreaty.maps.arcgis.com/apps/webappviewer/index.html?id=0a2a8ea1a16340f5a06ccf598e6d42f7 on 21 september 2022. secretariat of the antarctic treaty 2020. visited sites in antarctica. (map.) accessed on the internet at https://antarctictreaty.maps.arcgis.com/apps/webappviewer/index.html?id=60c3631b45dd404abe22b0d08a05ea06 on 21 september 2022. shitzer a. 2006. wind-chill-equivalent temperatures: regarding the impact due to the variability of the environmental convective heat transfer coefficient. international journal of biometeorology 50, 224–232, doi: 10.1007/s00484-005-0011-x. sikora s., araźny a., budzik t., migała k. & puczko d. 2010. warunki meteorologiczne i biometeorologiczne okolic hornsundu (spitsbergen zachodni) w roku 2009. (meteorological and biometeorological conditions in the hornsund region [western spitsbergen] in 2009.) problemy klimatologii polarnej 20, 83–101. sikora s., budzik t., migała k. & puczko d. 2011. warunki meteorologiczne i biometeorologiczne południowo-zachodniego svalbardu w 2010 roku. (meteorological and biometeorological conditions of south-west svalbard in 2010.) problemy klimatologii polarnej 21, 213–228. simmonds i., keay k. & lim e.p. 2003. synoptic activity in the seas around antarctica. monthly weather review 131, 272–288, doi: 10.1175/1520-0493(2003)131<0272:saitsa>2.0.co;2. simpson a. & maynard v. 2012. a longitudinal study of the effect of antarctic residence on energy dynamics and aerobic fitness. international journal of circumpolar health 71, article no. 17227, doi: 10.3402/ijch.v71i0.17227. siple p.a. & passel c.f. 1945. measurements of dry atmospheric cooling in subfreezing temperatures. proceedings american philosophy society 89, 177–199. styszyńska a. 1989. warunki bioklimatyczne w rejonie stacji arctowskiego w okresie lata. (biometeorological conditions in vicinity of arctowski station during summer.) in a. olszewski (ed.): dorobek i perspektywy polskich badań polarnych, xvi sympozjum polarne, toruń. (achievements and perspectives of polish polar research. 16th international polar symposium, toruń. pp. 248–250. toruń, poland: mikołaj kopernik university press. styszyńska a. 1994. ocena warunków bioklimatycznych w sezonie letnim na stacji arctowskiego. (evaluation of biometeorological conditions during summer at arctowski station.) yearbook of polish navy health service 25 (1990–1994), 174–187. styszyńska a. 2000. ochładzanie wiatrowe. (wind chill.) in a.a. marsz & a. styszyńska (eds.): główne cechy klimatu rejonu polskiej stacji antarktycznej im h. arctowskiego (antarktyka zachodnia. szetlandy południowe. wyspa króla jerzego). (the main features of the climate region of the polish antarctic station h. arctowski [west antarctica, south shetland islands, king george island].) pp. 163–181. gdynia, poland: gdynia maritime university press. turner j., maksym t., phillips t., marshall g.j. & meredith m.p. 2013. impact of changes in sea ice advance on the large winter warming on the western antarctic peninsula. international journal of climatology 33, 852–861, doi: 10.1002/joc.3474. uk hydrographic office 2004. the mariner’s handbook. taunton: united kingdom hydrographic office. węglowska e. 2021. warunki biometeorologiczne w okolicy polskiej stacji antarktycznej im h.arctowskiego. (characteristics of biometeorological conditions in the area of arctowski polish antarctic station.) msc thesis, jagiellonian university, kraków. wilkońska a., maciejowski w., damaszke m., jerzak b., łabno r., matuszczak b., palikot e. & pińkowska k. 2020. tourist profile in polar regions on the example of visitors to the henryk arctowski polish antarctic station. folia turistica 55, 167–183, doi: 10.5604/01.3001.0014.2423. wilson o. 1967. objective evaluations of wind chill index by records of frostbite in antarctica. international journal of biometeorology 11, 29–32, doi: 10.1007/bf01424272. zafren k. 2021. non-freezing cold injury (trench foot). international journal of environmental research and public health 18, article no. 10482, doi: 10.3390/ijerph181910482. adult survival and annual movement patterns of common snipe in iceland research article adult survival and annual movement patterns of common snipe in iceland aevar petersen,1 sverrir thorstensen,2 ib k. petersen,3 scott w. petrek,4 kane brides,5 anna m. calvert,6 mark l. mallory,7 gregory j. robertson8 & sarah e. gutowsky7 1reykjavik, iceland 2akureyri, iceland 3department of ecoscience, aarhus university, aarhus, denmark 4wildfowl and wetlands trust, slimbridge wetland centre, slimbridge, uk 5wildfowl and wetlands trust, conservation evidence department, slimbridge, uk 6landscape science and technology division, environment and climate change canada, national wildlife research centre, carleton university, ottawa, ontario, canada 7biology, acadia university, wolfville, ns, canada 8wildlife research division, environment and climate change canada, mount pearl, nl, canada abstract the common snipe (gallinago gallinago) is a wader that breeds in subarctic regions from iceland to russia, and for which global populations are in decline. we studied snipe breeding in western iceland between 1998 and 2020, locating nests and ringing birds annually. in 2019 and 2020, we deployed geolocators on nesting adults to estimate the timing of their annual migration and the location of overwintering areas. birds moved principally between breeding locations in iceland to wintering areas in ireland, although some birds may winter farther north. we also found that apparent annual adult survival averaged 66%, but was higher in years with warmer, wetter winters. given the similarity of our survival estimates to those from snipe elsewhere, we suggest that adult survival is unlikely a major contributor to declining populations, and other factors like habitat loss may be of more concern. keywords gallinago gallinago; wintering; geolocator; nao; ireland; habitat loss abbreviations aic: akaike information criterion anodev: analysis of deviance ci: confidence interval gls: global location sensor (also known as light-level geolocator) iucn: international union for the conservation of nature kde: kernel density estimate nao: north atlantic oscillation p: probability pli: profile likelihood interval se: standard error   citation: polar research 2023, 42, 8616, http://dx.doi.org/10.33265/polar.v42.8616 copyright: polar research 2023. © 2023 a. petersen et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 7 march 2023 competing interests and funding: the authors report no conflict of interest. none of our funders had any influence on the content of the submitted or published manuscript or required approval of the final manuscript to be published. financial support was provided by mitacs (canada), the natural sciences and engineering research council (canada) and acadia university (canada). correspondence: mark l. mallory, biology, acadia university, 15 university ave., wolfville b4p 2r6, ns, canada. e-mail: mark.mallory@acadiau.ca   introduction wildlife monitoring programmes run through government, academics and community science are providing convincing and consistent evidence that many bird populations are in decline (e.g., paleczny et al. 2015; horns et al. 2018; rosenberg et al. 2019; neate-clegg et al. 2020; hertzog et al. 2021). particularly pronounced are declines found in waders, which have witnessed greater declines than other species (rosenberg et al. 2019; burns et al. 2021; koleček et al. 2021). while natural fluctuations in bird populations occur, notably in response to long-term drivers such as climate (e.g., duda et al. 2021), the widespread and consistent declining trends in recent decades across different groups of birds are principally attributable to anthropogenic threats, including habitat development (alteration, fragmentation or loss), climate change, pollution and extractive industries like agriculture, mining, forestry and fisheries (e.g., calvert et al. 2013; reif 2013). furthermore, understanding drivers and managing populations of broadly distributed migratory birds that cross international borders present an additional set of logistical, political and regulatory challenges, especially if they are harvested (nichols et al. 1995; elmberg et al. 2006). consequently, understanding factors that influence different bird populations will be the key to our ability to manage, recover or sustain them in the future. in many parts of europe and north america, a subset of the waders—the snipes and woodcocks—have seen populations in decline (ferrand 2006; franks et al. 2018) and, indeed, are amongst the most threatened bird guilds in europe (zmilhorski et al. 2018). for example, long-term declines in these species have been found in northern ireland (henderson et al. 2002), great britain (heward et al. 2015), sweden (svensson 2000) and poland (żmihorski et al. 2018). many factors are known to negatively influence the breeding success and, ultimately, population numbers of waders and waterbirds, including changes in land-cover to intensify agriculture (e.g., colhoun et al. 2015), increasing numbers of predators (macdonald & bolton 2008), habitat losses at migratory stop-over and wintering sites (iwamura et al. 2013), and warming climate patterns influencing moisture (weiser et al. 2018). sæther & bakke (2000) showed that, for most bird populations, population growth is most sensitive to changes in annual adult survival. more recently, weiser et al. (2020) showed that better information on vital rates for most wader species is required to improve demographic, model-based estimates of population trends, and in particular, measures of annual adult survival were a key need for all species. the common snipe (gallinago gallinago), herein snipe, is distributed across europe from iceland through russia, and the iucn not only lists it as of ‘least concern’ as of 2021 but also notes that the global population is decreasing (birdlife international 2021). in iceland, which hosts the faeroeensis subspecies (brehm 1831), it is amongst the most common and widely distributed of waders (asbirk et al. 1997; gunnarsson et al. 2006; jóhannesdóttir et al. 2014). most of the iceland population is migratory, with available recoveries of ringed birds suggesting overwintering in the british isles, but there is some variation in migratory strategies, as some birds remain in southern iceland (petersen 1998; henderson 2002; svazas & paulauskas 2006). population trends in iceland as a whole have not been published (wentworth 2015), although local studies are found (e.g., ragnarsdóttir et al. 2021). studies on nesting birds, population trends as well as ringing of adult females and chicks, have been undertaken for several decades as part of long-term studies of birds on the island of flatey in western iceland (petersen 1979; petersen & thorstensen 2003). here, we use more than 20 years (1998–2020) of ringing data to estimate apparent adult survival rate of snipe breeding on flatey. moreover, encouraged by the results of gls technology in bird research (e.g., stutchbury et al. 2009), we deployed glss on nesting females in 2019 and 2020 and recovered them in subsequent years. those results, reported here, provide insights into the wintering range of this breeding population of snipe. with this additional information on wintering range, we relate apparent annual survival rates to climate conditions experienced by snipe to examine their potential to influence snipe survival. methods study site and data collection this study was carried out on flatey, a small island (total area of 0.5 km2) in the bay of breiðafjörður in western iceland (65.37°n, 22.92°w; fig. 1). the main study area is restricted to the western third of the island, which is mostly a mixture of meadows and dry hummocky moorland. a single gravel road runs through the middle of that part of the island, which has two farms, including buildings, gardens, small hayfields and grazing sheep. the island is visited by thousands of tourists every summer, and a few cruise liners call in for parts of days. a small village, with a hotel, is located on the island, with most houses occupied by summer residents. fig. 1 map of iceland, showing the location of the study site, flatey island (asterisk), in the bay of breiðafjörður. the inset satellite image of flatey and surrounding islets was obtained from the esri map service (“world imagery” layer) using the basemaps r package (schwalb-willmann 2021). likely on account of the site’s adequate cover for nesting, moist soils for feeding and a total lack of terrestrial predators, the snipe breeding population density is exceptionally high on flatey. there are about 90 pairs on the island, or about 180 pairs/km², recorded during several breeding seasons. breeding occurs throughout the season from may through august in four nesting ‘waves.’ snipes are most reliably caught during incubation on the nest, and only the female snipe incubates, so most live captures are females. from 1998 to 2020, efforts were made each breeding season in two field excursions, in june and again in july, to find nests by flushing incubating birds and ringing as many as possible. nests were found using two main search methods: (1) unsystematic searching through suitable habitat on foot; and (2) systematic searching via ‘rope-dragging,’ whereby a 20-m long rope strung with pebble-filled cans was dragged by two persons walking parallel, such that any incubating birds between them would flush, which was recorded by one to four persons walking a short distance behind the rope (see jackson 2004). nests were also found incidentally, either during other research activities or as reported by local people. once nests were located, hand-held nets were placed over the nest, and the area was left for 15–30 minutes to allow the female time to return. when approached, the snipe usually flew straight up from the nest and into the net. captured snipe were measured, weighed and ringed with a uniquely numbered metal ring. all live recoveries were from nest trapping; dead recoveries from ringed birds were found through chance by researchers and residents, or they were reported to the icelandic bird-ringing office in reykjavik. attempts were made each year to find as many nests and to capture as many females as possible, but variable weather conditions (e.g., we avoided disturbing birds during periods of substantial rain) and logistical constraints meant that nest finding effort and capture rates varied annually. to quantify nest finding effort each year, the total ‘personnel days’ (i.e., number of days conducting research on snipe multiplied by the number of field personnel during each campaign) was tabulated. additionally, ‘search effort’ was scored according to a scale from 1 to 7, representing the search methods used and the proportion of the island searched in each of the two excursions (table 1). total ‘search effort’ was taken as the sum of scores from each field trip, creating a relative ordinal search effort index ranging from 2 to 14. the search effort index was linearly correlated with personnel days (r2 = 0.72, p < 0.0001), as larger teams and longer field trips allowed for greater search effort. furthermore, there was a strong linear relationship between the number of nests found and the search effort index (r2 = 0.84, p < 0.0001), but less so between the number of nests found and personnel days (r2 = 0.47, p = 0.023). we therefore scaled the number of nests found by search effort and used the proportion of captured females relative to total nests found scaled for effort as an annual index of capture effort and success (fig. 2). table 1 criteria for scoring of nest-finding ‘search effort’ for common snipe (gallinago gallinago) on flatey, iceland, during the breeding seasons from 1998 to 2020. search effort was scored independently for two field campaigns each year (june and july) based on the search methods used and the proportion of the island searched in each campaign, then summed to create an annual relative search effort index ranging from 2 to 14. score search methods proportion of island searched (%) 1 unsystematic, incidental <100 2 unsystematic, incidental 100 3 rope-dragging 33 4 rope-dragging, incidental 33 5 rope-dragging, incidental 50 6 rope-dragging, incidental 66 7 rope-dragging, incidental 100 fig. 2 time series of nests found per unit search effort for common snipe (gallinago gallinago) on flatey, iceland. linear regression indicated an overall decline over the study period (r2 = 0.44, slope estimate = -0.22 ± 0.05 se, p < 0.001, dashed blue line). loess smoother is shown with a solid line (the 95% ci indicated with grey shading), where the intersection with the linear trend corresponds to the changepoint identified at 2009 (95% ci = 2005–2013, p < 0.001). non-breeding distributions by geolocation in june and july 2019, 17 biotrack ltd. gls devices (model mk5090) were deployed on captured female snipe. devices were leg-mounted using a modified colour ring with a flag. the mass of the ring, device, tie and glue was ca. 1.35g (based on other studies), representing <1.5% of the body mass of equipped birds (range 100–135 g, n = 21). in 2020, five devices were recovered, four of which provided reliable data. new gls devices were deployed on each of these five recaptured females in 2020, and two were recaptured in june 2021 (one from the initial failed logger bird), providing data for a total of six non-breeding seasons from five individual females. at recapture in 2020, three of five birds had developed skin lesions of varying severity on the tibia due to the device attachment. we did not include capture histories from individuals fitted with gls in the analysis of survival in case of device effects on breeding behaviour or return rates. the devices measured light levels and recorded maximum levels at two-minute intervals. data were downloaded and decompressed using the bas track software (biotrack ltd.). data were limited to the period between 1 august in 2019 and 15 may 2020, when positional estimates stabilized in the expected general latitudinal and longitudinal range of the breeding site. we excluded data from a six-week window around the fall and spring equinox before processing (e.g., gutowsky et al. 2021). the species’ tendency to remain hidden in vegetation (van gils et al. 2020) renders positional estimation from light level data challenging, and error around positional estimates is assumed to be substantial, likely to be at the upper end of the estimated gls error, which is between ca. 140 and 200 km (lisovski et al. 2012). using data from six snipe-years, we estimated general distributions and migratory movements for birds breeding at flatey as follows. twilight events were using the findtwilights function in the twgeos package (wotherspoon et al. 2016) in programme r (r version 2.15.2), with a light threshold of 2 and a minimum darkness period between sunset and sunrise of 3 hours to filter spurious twilight transitions caused by shading, weather or light pollution. transitions were examined to filter or remove incorrect sunrise/sunset times with the twilightedit function, based on the following: (1) if a transition had a time difference of >60 minutes from transitions within a two-day window on either side, and the transitions within that window were all within 30 minutes of one another, then the transition time was flagged and adjusted to the median of the window; and (2) if a transition time was >60 minutes different to the window, but the transitions within the window were more variable than expected for stationary behaviour, the transition was flagged as a candidate for removal. for positional estimation from sunrise/sunset transition events, the coord function in the geolight package, version 2.0 (lisovski & hahn 2012), was used based on a range of potential sun elevation angles (-5 to 5°). for each angle, we plotted the estimates and selected the sun angle that resulted in the closest match in latitude estimates before and after equinoxes, the highest proportion of positions fitted within a reasonable latitudinal and longitudinal range of the breeding area during the post-breeding and pre-breeding periods, and the best fit over land within the known overwintering range. final sun angles were chosen between -2.5 and -0.5°. stationary periods were delineated based on patterns of sunrise and sunset using the function changelight, with a minimum stationary duration of 10 days. stationary periods less than two days and 150 km apart were merged, and the overwinter phase was identified as the longest duration stationary period. to illustrate distributions of birds during overwintering, we generated individual kdes with the adehabitathr package (calenge 2006), using a smoothing parameter of two and a 2° × 2° grid cell size, based on the mean accuracy of the gls devices (delord et al. 2019). five-day rolling means of longitude plotted against time were used to estimate the timing of east–west migratory movements, as longitude estimates are prone to lower error and allowed us to approximate movements to and from the general breeding area in west iceland as well as movements across iceland before and after migrating. nesting population and survival analysis to examine potential temporal trends in the nesting population over the course of the study period, a linear regression and breakpoint regression were fitted to a time-series of nests found per unit search effort using the package chngpt (fong et al. 2017). breakpoints are determined using a piecewise linear regression that fits two linear regressions split at a non-continuous break point (i.e., “stegmented” or stepped and segmented) estimated to minimize residual variance. to analyse the ringing data, we implemented joint live encounter–dead recovery burnham models (burnham 1993) in program mark, version 6.0, using the package rmark (laake 2014). this model allows estimation of apparent survival (st; probability an individual survives the interval from year t to year t + 1), live recapture rate (pt; probability of live encounter and capture in year t given that the individual survived the preceding interval and is in the study area) and fidelity to the study area (ft; probability that an individual present in the study area in year t is also present in the study area in year t + 1, given that it is alive in year t + 1), as well as the seber dead recovery rate (rt; the probability that an individual that dies in year i is found and reported). the set of candidate models to be considered was based on a priori expectations. because of the sparseness of recoveries, we restricted the dead recovery parameter r to be constant over our study period in all models. live recaptures and dead recoveries within the study period were restricted to the study site, so we fixed the fidelity parameter f to 1 in all models (cooch & white 2017). parameter s therefore did not represent true survival but instead ‘local’ or ‘apparent’ survival, which could be confounded with permanent emigration from the study site. s and p were allowed to vary annually (t). the fully saturated general model {st pt ff=1 r.} had 46 parameters, and most st and pt were poorly estimated or inestimable. live recapture rate p was expected to vary with time, as the number of field days, size of field crews, nest search effort and nests found varied considerably amongst field seasons over the course of the study. to reduce the dimensionality of the parameter space, we explored reduced parameter models of p and saw clear evidence that the annual index of capture effort improved model fit over the time-variant model. our starting model then included time-varying survival with recapture constrained to co-vary with capture effort {st peffort ff=1 r.}. to test the hypothesis that snipe apparent annual survival co-varied with broad weather patterns, we looked for a relationship between apparent survival and the nao during three annual periods: the full year (naoyr) from may (in year t) to april (in year t + 1); the breeding season (naobr) from may to august (in year t); and the overwinter months (naoow) from november (in year t) to march (in year t + 1; fig. 3). the nao is the most dominant teleconnection pattern in the north atlantic, describing the strength of the sea-level pressure difference between the icelandic low and the azores high (krueger et al. 2019). during a positive nao, conditions in northern europe are warmer and wetter than average, whereas during negative nao, conditions are colder and drier than average (visbeck et al. 2001). the nao is also positively correlated with increased winter storm activity in the north-east atlantic, particularly since the 1970s in northern europe (krueger et al. 2019). fig. 3 time series of covariates used in joint live encounter–dead recovery burnham models to estimate common snipe (gallinago gallinago) adult female survival. live recapture (p) is constrained in all models to vary with an index of capture effort (captures/nest found/search effort). survival covariates include the nao index during the breeding months, the overwinter months and the full year. prior to model selection, we examined the live encounter data to identify any biologically explicable sources of poor model fit (pradel et al. 2003) using the r2ucare package to test cormack-jolly-seber goodness-of-fit (gimenez et al. 2018). tests for transience of individuals (test3.sr) and trap-dependence (test2.ct) were non-significant. we also tested the fully saturated general live encounter–dead recovery burnham model without covariates for overdispersion (ĉ > 1.00) by calculating fletcher ĉ (fletcher 2012), bootstrap goodness of fit ĉ and the median ĉ (white & burnham 1999). none of these goodness-of-fit assessments indicated the data were over-dispersed (fletcher ĉ = 0.99, bootstrap goodness-of-fit ĉ = 0.95, median ĉ = 0.98), so aic adjustments were not needed (burnham & anderson 2002). the models in the candidate model set were compared via differences in sample-size-corrected aic values (δaicc, where the best-fit model has the lowest aicc value) as well as relative akaike model weights (wi, which sum to 1 and provide an index of support for each model relative to the total candidate model set [akaike 1973; burnham & anderson 2002]). we applied anodev to assess the statistical significance and the fraction of temporal variation explained by covariates in the top models (lebreton et al. 1992; skalski 1996). support for specific predictors was also evaluated from effect sizes evaluated at the scale (logit) of the linear predictor. finally, we derived an apparent mean apparent survival rate calculated with a variance components approach using the var.covar function via a {st peffort ff=1 r.} model structure, which provides an estimates of time-dependent process variation (σ2) in apparent annual survival probabilities. estimates and effect sizes are all presented as means ± se, along with associated 95% plis. results non-breeding distributions from the geolocator data recovered from six individuals, kde indicated the overwinter distribution for female snipe equipped with glss in the breeding season of 2019 fell primarily along the west coast of ireland for three birds, and likely in the faroe islands for the fourth (fig. 4). for snipe equipped in 2020, the central overwinter distribution shifted north towards northern ireland and scotland, with one bird likely spending some time in the faroe islands as well (fig. 2). migration from iceland occurred before the fall equinox for two birds (c-2019 and d-2020), and during or after the fall equinox for the other four (fig. 5). one bird remained in iceland until late october (e-2020), while the others initiated migration between late august and early october (fig. 5). the stationary overwinter period lasted 109 ± 45 days, beginning between 9 october and 30 november and ending between 6 february and 14 april. mean distances travelled between the study area and the centroids of overwinter kde contours were 1369 ± 251 km. spring return migration was initiated in april, with all birds returning to iceland by may (fig. 5). fig. 4 overwintering distribution of female adult common snipe (gallinago gallinago; n = 5, individual d tracked twice) during the period october to april determined using glss deployed during the 2019 and 2020 breeding seasons on flatey, iceland. distributions are shown based on the 25% (light purple shading) to 75% (dark purple shading) contours (from kernel density estimation. fig. 5 longitudinal position over time of female adult common snipe (gallinago gallinago; n = 5, individual d tracked twice) determined using glss deployed during the 2019 and 2020 breeding seasons on flatey, iceland. dark blue dotted lines represent the longitudinal limits of iceland, and the light blue dashed line indicates the longitude of the study site. coordinates are shown as five-day rolling mean values of longitude. female apparent adult survival during the study period (1998–2020), a sample of 455 adult female snipe provided 830 live recaptures and 10 dead recoveries. the number of nests found, and the number of females recaptured ranged from 16 nests and eight females in 2014 to 131 nests and 78 females in 2006. the number of nests found relative to the amount of nest search effort exhibited an overall linear decline over the study period (r2 = 0.44, slope estimate = -0.22 ± 0.05, p < 0.001) with a changepoint identified at 2009 (95% ci = 2005–2013, p < 0.001; fig. 2). the top-ranked joint live encounter–dead recovery burnham model, where apparent survival probability co-varied with winter nao and live recapture probability co-varied with capture effort {snaowin peffort ff=1 r.}, garnered 52% of the model support (table 2). unconstrained live recapture probability ranged p = 0.24–0.54, and the effect size of capture effort was small but did not bound zero (βeffort = 0.20, se = 0.04, 95% pli = 0.12–0.27). the probability of recovering a marked bird if it died during the study was low (mean r = 0.02, se = 0.01, 95% ci = 0.01–0.04). while the effect size of winter nao on apparent survival did not bound zero (βnaowin = 0.33, se = 0.16, 95% ci = 0.03–0.64), anodev indicated that the percentage of annual variation in apparent survival explained by winter nao variability was small (7.1%; fig. 6). predicted apparent survival estimates varied from 0.76 ± 0.04 (0.68–0.82) in 2015 when winter nao reached a high of 1.42, to 0.57 ± 0.06 (0.45–0.68) in 2009 when nao was lowest at -1.26. table 2 joint live encounter–dead recovery burnham model (seber parameterization) results used to estimate common snipe (gallinago gallinago) adult female survival on flatey, iceland, with aic adjusted for small sample size (δaicc) and akaike weight (w). model parameters include apparent survival (s), live recapture (p), fidelity (f) and dead recovery (r) probabilities. live recapture (p) is constrained to vary with capture effort (effort). f is fixed to 1 and r is constant in all models. because all models are of the form {s( ) peffort ff=1 r.}, only the s parameter is shown in the table. the notation (.) indicates the parameter is treated as constant, and (t) indicates full time dependence (different values for each year). covariates include nao index during the breeding months (naobr), overwinter months (naowin) and year (naoyr), and an effect of a changepoint at 2009 (cp2009). model δaicc w deviance parameters {snaowin} 0.00 0.52 673.01 5 {snaoyr} 1.58 0.23 674.59 5 {s.} 2.10 0.18 677.12 4 {scp2009} 3.98 0.07 676.99 5 {st} 21.21 0.00 650.55 26 {snaobr} 39.46 0.00 712.47 5 fig. 6 unconstrained survival probability of adult female common snipe (gallinago gallinago) according to the model {st peffort ff=1 r.} relative to winter nao index during the overwinter season (november–march) from 1998 to 2019 (points with 95% ci error bars). boundary estimates for years when the model failed to estimate s are not shown. shown as upward-trending horizontal line (with the 95% confidence interval indicated in grey) are predicted values of survival generated from the model {snaowin peffort ff=1 r.} for a range of nao values. the second-ranked model with 23% of model weight included apparent survival varying with annual nao and live recapture probability varying with effort {snaoyr peffort ff=1 r.} (δaicc = 1.58, table 2). however, the annual nao effect on s did not differ from zero (βnaoyr = 0.48 ± 0.30, 95% ci = -0.10–1.06). the majority of the remaining model support (18%) went to a model that held apparent survival constant over time {s. peffort ff=1 r.}, with δaicc = 2.10 (table 2). time-invariant apparent survival probability was estimated as 0.69 ± 0.02. it is possible to provide a mean apparent survival rate from our top model; however, the estimate would be constrained by the winter nao covariate. instead, we used the variance components method to take into account annual variance and sampling variance in apparent survival rate. the time-varying survival model {st peffort ff=1 r.} failed to estimate s in five of the later years (fig. 6). from the remaining estimates, our mean estimate of apparent survival from the time-varying model considering sampling error was 0.66 ± se 0.03, with a process variance (σ2 = 0.005, 95% ci = -0.001–0.03) accounting for a small proportion of the total annual variance (process + sampling variance) in the data. discussion this study provides novel insights into the biology of the common snipe breeding in western iceland. our geolocator data confirm what limited ringing data previously suggested, that is, some snipe from iceland winter in ireland (petersen 1998; henderson 2002), although some ringed birds have been found as far south as portugal (asensio & carrasca 1987). boyd & petersen (2006) found that spring arrival dates at the breeding grounds had advanced in the 20th century, presumably influenced by global warming. when we estimated apparent annual adult survival for female snipe, we also found that climate patterns had a small but significant effect, with warmer, wetter winters, resulting in higher apparent survival. snipe are harvested in parts of their winter range (tapper 1992), and changing climate patterns that influence overwinter survival may have important implications for conservation management of this species in the future. our tracking confirmed that common snipe that breed in iceland overwinter mainly in ireland, although we suggest that they may also winter in scotland. snipes are hunted in ireland and scotland, but harvest statistics are not collected in ireland. estimates for the uk as a whole in 1995 were 30 000 hunted birds (e.g., murray & simcox 2003). better data, especially from ireland, would help determine whether harvest pressure varies annually and, consequently, whether human hunting contributes to variation in snipe survival (which we could not account for in our analysis). moreover, researchers have suggested that large-scale habitat changes, notably drainage of agricultural land (about 1.4 million ha, 1950–1979), contributed to declines of snipe in ireland (lang 1988; colhoun et al. 2015). consequently, the evidence for strong migratory connections between the british isles and iceland highlights the importance of international coordination to manage snipe populations. we also found that one snipe wintered farther north than the others. while the snipe is a common breeding bird on the faroe islands, with 1500–3000 breeding pairs recorded there, numbers increase during the migratory periods, presumably due to migrants passing through from iceland and possibly also from the northernmost regions of europe (hammer et al. 2014). our results support the notion that icelandic birds likely use the faroes as a migratory stop-over, with some electing to remain for the winter, as some do in iceland (petersen 1998; svazas & paulauskas 2006). further tracking work, perhaps with more precise locations from gps loggers deployed at multiple sites in iceland, will confirm the migratory routes of icelandic snipe. we estimated apparent adult survival of female common snipe nesting in western iceland as 0.66 ± se 0.03, which yields an average lifespan of about 2.4 years (the oldest bird was one adult recaptured 12 years after ringing). this rate is similar to, or higher than, those reported in earlier studies. for example, common snipe wintering in france had survival rates of 0.44–0.52, depending on whether they wintered at interior or coastal regions (péron et al. 2013), and populations were considered stable. spence (1988) estimated survival of uk snipe at 62.5%, using less advanced statistical approaches. arnold et al. (2016) reported a remarkably similar survival rate of 0.653 for the closely related wilson’s snipe (gallinago delicata) in north america, where the population appears to be increasing (birdlife international 2021). survival rates for the american woodcock (scolopax minor) have been estimated as 0.49 (krementz et al. 2003), and tavecchia et al. (2002) reported adult survival of 0.44 for eurasian woodcock (scolopax rusticola). therefore, while we lack adult survival rates from other sites in iceland, the rates from flatey appear similar to or greater than what has been reported for similar species elsewhere. variable survival rates between study populations may be related to the intensity of mortality, such as due to hunting. although the overall apparent annual survival rate was consistent with other studies, we found substantial annual variation in survival. some variation may have been due to emigration (which we could not measure well but which could confound mortality estimates); we recorded one instance of an adult ringed at the nest and recovered alive seven years later at a site 29 km north during the breeding season. however, variation was also explained by climate indices, in particular the nao. this index had its absolute minimum in 2010 over the period 1875–2020, and in the years thereafter, the nao was mostly positive (krueger et al. 2019). the winter of 2009/10 was the coldest winter in 50 years in ireland, and the following year (november/december 2010) experienced another severe cold spell (irish meteorological service data at https://www.met.ie/climate/major-weather-events), corresponding to the two lowest winter nao indices during the study period (fig. 3). this also corresponds to the sustained decline in the number of nests found on flatey beginning in 2010, even after accounting for search effort. following 2010, the diminished nesting population and subsequent low capture rates at flatey impeded our ability to obtain estimates for survival in most years. nonetheless, we interpret these results as suggesting that winters of extreme low nao and cold, dry conditions have had a greater negative effect on snipe survival than years of high winter storm activity. our data are consistent with other studies that have shown that extreme weather events can have important consequences for abundance, survival and overall population demography in a variety of bird species (e.g., frederiksen et al. 2008; gardner et al. 2017; cohen et al. 2021). we caution that the unique attributes of our study site should be considered when interpreting the results, which may not apply to the entire icelandic snipe population. for example, two farms operate on flatey. common eider (somateria mollissima) resources, including eiderdown, are collected (petersen 1979), and avian predators such as ravens (corvus corax) and great black-backed gulls (larus marinus) are actively deterred. our nesting snipe may experience lower risks of predation than snipe elsewhere; they may also experience greater disturbance from people and sheep, as both can move freely over much of the core nesting area (petersen 1979). disturbance can negatively influence nesting success (götmark 1992), although it is less likely to affect adult survival (but see gibson et al. 2018). we suspect that disturbance is not a major factor, as snipe nesting density is much higher on the western, inhabited part of the island than the eastern, uninhabited area, which is also a nature reserve and closed to visitors for most of the summer. for snipe nesting on flatey, disturbance by people and livestock may not pose a problem because of the lack of predators, in contrast to what has been found for waders elsewhere (e.g., st. clair et al. 2010). for context, we recently examined adult survival in arctic terns (sterna paradisaea) and common eiders nesting on flatey, and estimated rates were amongst the highest reported for each species (petersen et al. 2020; wood et al. 2021). the snipe apparent survival rate on flatey could be a bit higher than elsewhere on mainland iceland, where nesting birds may experience predation pressure from feral american mink (neovison vison) and arctic fox (vulpes lagopus). while extreme years may have important impacts on survival that could be having long-term impacts on the population, snipe appear to be highly resilient and adapted to harsh breeding and overwintering conditions. for the icelandic breeding population, migration is relatively short and quick, so perhaps it is not surprising that apparent survival is relatively consistent and high; short-distance migrants likely face fewer challenges from the effects of warming climates than long-distance migrants (e.g., both et al. 2010; clausen & clausen 2013; rotics et al. 2017). perhaps of more immediate concern for snipe is the pattern of habitat change, as climate warming dries out their preferred moist sites or as people drain land for agriculture or urban expansion (reviewed by green et al. 2017). we recommend additional tracking studies, particularly using gps technology, to increase sample size and identify more precisely stop-over and wintering areas for common snipe from iceland, with a goal of identifying and conserving internationally important habitat sites in the face of habitat change. acknowledgements the authors thank the many field assistants who assisted with monitoring, capturing and ringing snipe over the decades of this project, and hafsteinn guðmundsson and svanhildur jónsdóttir, flatey farmers who provided access to their land, so we could conduct our work. the authors note in particular the fieldwork contributions of anna björg petersen, benedikt ernir magnússon, eyþór ingi jónsson, magnús ingi óskarsson, matthías ævar magnússon and jonathan cooper. the authors also thank two referees for their comments that improved our manuscript. compliance with ethical standards all work was conducted under approved ringing permits in iceland. references akaike h. 1973. information theory and an extension of the maximum likelihood principle. in b.n. petrov & f. csaki (eds.): proceedings of the 2nd international symposium on information theory. pp. 267–281. budapest: akademiai kiado. arnold t.w., de sobrino c.n. & specht h.m. 2016. annual survival rates of migratory shore and upland game birds. wildlife society bulletin 40, 470–476, doi: 10.1002/wsb.669. asbirk s., berg l., hardeng g., koskimies p. & petersen a. 1997. population sizes and trends of birds in the nordic countries 1978–1994. temanord 1997(614). copenhagen: nordic council of ministers. asensio b. & carrasca l.m. 1987. migration of common snipe (gallinago gallinago) wintering in the iberian peninsula. ardeola 34, 225–242. birdlife international. 2021. iucn red list for birds. accessed on the internet at http://www.birdlife.org on 15 november 2021. both c., van turnhout c.a., bijlsma r.g., siepel h., van strien a.j. & foppen r.p. 2010. avian population consequences of climate change are most severe for long-distance migrants in seasonal habitats. proceedings of the royal society b 277, 1259–1266, doi: 10.1098/rspb.2009.1525. boyd h. & petersen a. 2006. spring arrivals of migrant waders in iceland in the 20th century. ringing and migration 23, 107–115, doi: 10.1080/03078698.2006.9674353. brehm c.l. 1831. handbuch der naturgeschichte aller vögel deutschlands. (handbook of the natural history of all birds in germany.) ilmenau: berhard friedrich voigt verlag. burnham k.p. 1993. a theory for combined analysis of ring recovery and recapture data. in j.d. lebreton & p.m. north (eds.): marked individuals in the study of bird population. pp. 199–213. basel: birkhauser verlag. burnham k.p. & anderson d.r. 2002. model selection and multimodel inference: a practical information–theoretic approach. 2nd edn. berlin: springer. burns f., eaton m.a., burfield i.j., klvaňová a., šilarová e., staneva a. & gregory r.d. 2021. abundance decline in the avifauna of the european union reveals cross‐continental similarities in biodiversity change. ecology and evolution 11, 16647–16660, doi: 10.1002/ece3.8282. calenge c. 2006. the package “adehabitat” for the r software: a tool for the analysis of space and habitat use by animals. ecological modeling 197, 516–519, doi: 10.1016/j.ecolmodel.2006.03.017. calvert a., bishop c., elliot r., krebs e., kydd t., machtans c. & robertson g. 2013. a synthesis of human-related avian mortality in canada. avian conservation and ecology 8, doi: 10.5751/ace-00581-080211. clausen k.k. & clausen p. 2013. earlier arctic springs cause phenological mismatch in long-distance migrants. oecologia 173, 1101–1112, doi: 10.1007/s00442-013-2681-0. cohen j.m., fink d. & zuckerberg b. 2021. extreme winter weather disrupts bird occurrence and abundance patterns at geographic scales. ecography 44, 1143–1155, doi: 10.1111/ecog.05495. colhoun k., mawhinney k. & peach w.j. 2015. population estimates and changes in abundance of breeding waders in northern ireland up to 2013. bird study 62, 394–403, doi: 10.1080/00063657.2015.1058746. cooch e.g. & white g.c. 2017. program mark—a gentle introduction. 17th edn. accessed on the internet at http://www.phidot.org/software/mark/docs/book/ on 17 january 2022. delord k., barbraud c., pinaud d., ruault s., patrick s.c. & weimerskirch h. 2019. individual consistency in the non-breeding behavior of a long-distance migrant seabird, the grey petrel. procellaria cinerea. marine ornithology 47, 93–103. duda m.p., hargan k.e., michelutti n., blais j.m., grooms c., gilchrist h.g., mallory m.l., robertson g.j. & smol j.p. 2021. reconstructing long-term changes in avian populations using lake sediments: opening a window onto the past. frontiers in ecology and evolution 9, article no. 698175, doi: 10.3389/fevo.2021.698175. elmberg j., nummi p., pöysä h., sjöberg k., gunnarsson g., clausen p., guillemain m., rodrigues d. & väänänen v.m. 2006. the scientific basis for new and sustainable management of migratory european ducks. wildlife biology 12, 121–127, doi: 10.2981/0909-6396(2006)12[121:tsbfna]2.0.co;2. ferrand y. (ed.) 2006. sixth european woodcock and snipe workshop. proceedings of an international symposium of the wetlands international woodcock and snipe specialist group, 25–27 november 2003, nantes, france. international wader studies 13. wageningen: wetlands international. fletcher d.j. 2012. estimating overdispersion when fitting a generalized linear model to sparse data. biometrika 99, 230–237, doi: 10.1093/biomet/asr083. fong y., huang y., gilbert p.b. & permar s.e. 2017. chngpt: threshold regression model estimation and inference. bmc bioinformatics 18, article no. 454, doi: 10.1186/s12859-017-1863-x. franks s.e., roodbergen m., teunissen w., carrington cotton a. & pearce‐higgins j.w. 2018. evaluating the effectiveness of conservation measures for european grassland‐breeding waders. ecology and evolution 8, 10555–10568, doi: 10.1002/ece3.4532. frederiksen m., daunt f., harris m.p. & wanless s. 2008. the demographic impact of extreme events: stochastic weather drives survival and population dynamics in a long‐lived seabird. journal of animal ecology 77, 1020–1029, doi: 10.1111/j.1365-2656.2008.01422.x. gardner j.l., rowley e., de rebeira p., de rebeira a. & brouwer l. 2017. effects of extreme weather on two sympatric australian passerine bird species. philosophical transactions of the royal society b 372, article no. 20160148, doi: 10.1098/rstb.2016.0148. gibson d., chaplin m.k., hunt k.l., friedrich m.j., weithman c.e., addison l.m., cavalieri v., coleman s., cuthbert f.j., fraser j.d. & golder w. 2018. impacts of anthropogenic disturbance on body condition, survival, and site fidelity of nonbreeding piping plovers. the condor 120, 566–580, doi: 10.1650/condor-17-148.1. gimenez o., lebreton j.-d., choquet r. & pradel r. 2018. r2ucare: an r package to perform goodness‐of‐fit tests for capture–recapture models. methods in ecology and evolution 9, 1749–1754, doi: 10.1111/2041-210x.13014. götmark f. 1992. the effects of investigator disturbance on nesting birds. current ornithology 9, 63–104, doi: 10.1007/978-1-4757-9921-7_3. green a.j., alcorlo p., peeters e.t., morris e.p., espinar j.l., bravo‐utrera m.a., bustamante j., díaz‐delgado r., koelmans a.a., mateo r. & mooij w.m. 2017. creating a safe operating space for wetlands in a changing climate. frontiers in ecology and the environment 15, 99–107, doi: 10.1002/fee.1459. gunnarsson t.g., gill j.a., appleton g.f., gislason h., gardarsson a., watkinson a.r. & sutherland w.j. 2006. large-scale habitat associations of birds in lowland iceland: implication for conservation. biological conservation 128, 265–275, doi: 10.1016/j.biocon.2005.09.034. gutowsky s.e., davis s.e., maftei m. & mallory m.l. 2021. flexibility in migratory strategy contrasts with reliance on restricted staging and overwintering grounds for sabine’s gulls from the canadian high arctic. animal migration 8, 84–97, doi: 10.1515/ami-2020-0106. hammer s., madsen j.j., jensen j.-k., pedersen k.t., bloch d. & thorup k. 2014. færøsk trækfugleatlas/the faroese bird migration atlas. tórshavn: faroe university press. (in danish with english summary.) henderson i. 2002. common snipe (snipe) gallinago gallinago. in c. wernham et al. (eds.): the migration atlas. movements of the birds of britain and ireland. pp. 316–318. london: t. & a.d. poyser. henderson i.g., wilson a.m., steele d. & vickery j.a. 2002. population estimates, trends and habitat associations of breeding lapwing vanellus vanellus, curlew numenius arquata and snipe gallinago gallinago in northern ireland in 1999. bird study 49, 17–25, doi: 10.1080/00063650209461240. hertzog l.r., frank c., klimek s., röder n., böhner h.g. & kamp j. 2021. model‐based integration of citizen science data from disparate sources increases the precision of bird population trends. diversity and distributions 27, 1106–1119, doi: 10.1111/ddi.13259. heward c.j., hoodless a.n., conway g.j., aebischer n.j., gillings s. & fuller r.j. 2015. current status and recent trend of the eurasian woodcock scolopax rusticola as a breeding bird in britain. bird study 62, 535–551, doi: 10.1080/00063657.2015.1092497. horns j.j., adler f.r. & şekercioğlu ç.h. 2018. using opportunistic citizen science data to estimate avian population trends. biological conservation 221, 151–159, doi: 10.1016/j.biocon.2018.02.027. iwamura t., possingham h.p., chadès i., minton c., murray n.j., rogers d.i., treml e.a. & fuller r.a. 2013. migratory connectivity magnifies the consequences of habitat loss from sea-level rise for shorebird populations. proceedings of the royal society b 280, article no. 20130325, doi: 10.1098/rspb.2013.0325. jackson s.f. 2004. monitoring methods for non-breeding snipe. british trust for ornithology research report 355. thetford: british trust for ornithology. jóhannesdóttir l., arnalds ó., brink s. & gunnarsson t.g. 2014. identifying important bird habitats in a sub-arctic area undergoing rapid land-use change. bird study 61, 544–552, doi: 10.1080/00063657.2014.962481. koleček j., reif j., šálek m., hanzelka j., sottas c. & kubelka v. 2021. global population trends in shorebirds: migratory behaviour makes species at risk. science of nature 108, article no. 9, doi: 10.1007/s00114-021-01717-1. krementz d.g., hines j.e. & luukkonen d.r. 2003. survival and recovery rates of american woodcock banded in michigan. journal of wildlife management 67, 398–407, doi: 10.2307/3802780. krueger o., feser f. & weisse r. 2019. northeast atlantic storm activity and its uncertainty from the late nineteenth to the twenty-first century. journal of climate 32, 1919–1931, doi: 10.1175/jcli-d-18-0505.1. laake j. 2014. rmark: r code for mark analysis. r package version 2.1.3. accessed on the internet at http://cran.r-project.org/web/packages/rmark/index.html on 17 january 2022. lang j.t. 1988. wildlife conservation in the republic of ireland. studies: an irish quarterly review 77, 165–173. lebreton j.‐d., burnham k.p., clobert j. & anderson d.r. 1992. modelling survival and testing biological hypothesis using marked animals: a unified approach with case studies. ecological monographs 62, 67–118, doi: 10.2307/2937171. lisovski s. & hahn s. 2012. geolight—processing and analysing light‐based geolocator data in r. methods in ecology and evolution 3, 1055–1059, doi: 10.1111/j.2041-210x.2012.00248.x. lisovski s., hewson c.m., klaassen r.h., korner‐nievergelt f., kristensen m.w. & hahn s. 2012. geolocation by light: accuracy and precision affected by environmental factors. methods in ecology and evolution 3, 603–612, doi: 10.1111/j.2041-210x.2012.00185.x. macdonald m. & bolton m. 2008. predation of wader nests in europe. ibis 150, 54–73, doi: 10.1111/j.1474-919x.2008.00869.x. murray m. & simcox h. 2003. use of wild living resources in the united kingdom: a review. petersborough: uk committee for international union for the conservation of nature. neate-clegg m.h., horns j.j., adler f.r., aytekin m.ç.k. & şekercioğlu ç.h. 2020. monitoring the world’s bird populations with community science data. biological conservation 248, article no. 108653, doi: 10.1016/j.biocon.2020.108653. nichols j.d., johnson f.a. & williams b.k. 1995. managing north american waterfowl in the face of uncertainty. annual review of ecology and systematics 26, 177–199, doi: 10.1146/annurev.es.26.110195.001141. paleczny m., hammill e., karpouzi v. & pauly d. 2015. population trend of the world’s monitored seabirds, 1950–2010. plos one 10, e0129342, doi: 10.1371/journal.pone.0129342. péron g., ferrand y., leray g. & gimenez o. 2013. waterbird demography as indicator of wetland health: the french-wintering common snipe population. biological conservation 164, 123–128, doi: 10.1016/j.biocon.2013.04.015. petersen a. 1979. varpfuglar flateyjar á breiðafirði og nokkurra nærliggjandi eyja. (the breeding birds of flatey and some nearby islets, in breiðafjördur.) náttúrufraedingurinn 49, 229–256. (in icelandic with english summary.) petersen a. 1998. ìslenskir fuglar. icelandic birds. reykjavík: vaka-helgafell. petersen a., robertson g.j., thorstensen s. & mallory m.l. 2020. annual survival of arctic terns in western iceland. polar biology 43, article no. 1843, doi: 10.1007/s00300-020-02749-5. petersen a. & thorstensen s. 2003. monitoring of icelandic shorebirds/waders. will climate change influence snipe populations? paper presented at the pan-arctic shorebird/wader monitoring and research workshop. 3–6 december, karrebæksminde. pradel r., wintrebert c.m.a. & gimenez o. 2003. a proposal for a goodness‐of‐fit test to the arnason‐schwarz multisite capture–recapture model. biometrics 59, 43–53, doi: 10.1111/1541-0420.00006. ragnarsdóttir s.b., thorstensen s. & metúsalemsson s. 2021. fuglalíf í óshólmum eyjafjarðarár: könnun 2020 með samanburði við fyrri ár. (birdlife in the delta area of the river eyjafjarðarár: 2020 survey results compared to previous years.) náttúrufræðistofnun íslands ní21001. akureyri: iceland institute of natural history. reif j. 2013. long-term trends in bird populations: a review of patterns and potential drivers in north america and europe. acta ornithologica 48, 1–16, doi: 10.3161/000164513x669955. rosenberg k.v., dokter a.m., blancher p.j., sauer j.r., smith a.c., smith p.a., stanton j.c., panjabi a., helft l., parr m. & marra p.p. 2019. decline of the north american avifauna. science 366, 120–124, doi: 10.1126/science.aaw1313. rotics s., turjeman s., kaatz m., resheff y.s., zurell d., sapir n., eggers u., fiedler w., flack a., jeltsch f. & wikelski m. 2017. wintering in europe instead of africa enhances juvenile survival in a long-distance migrant. animal behaviour 126, 79–88, doi: 10.1016/j.anbehav.2017.01.016. sæther b.e. & bakke ø. 2000. avian life history variation and contribution of demographic traits to the population growth rate. ecology 81, 642–653, doi: 10.1890/0012-9658(2000)081[0642:alhvac]2.0.co;2. schwalb-willmann j. 2021. basemaps: accessing spatial basemaps in r. r package version 0.0.1. accessed on the internet at https://cran.r-project.org/package=basemaps on 4 january 2022. skalski j.r. 1996. regression of abundance estimates from mark–recapture surveys against environmental covariates. canadian journal of fisheries and aquatic sciences 53, 196–204, doi: 10.1139/f95-169. spence i.m. 1988. mortality of snipe estimated from a mark and recapture study. ringing and migration 9, 27–31, doi: 10.1080/03078698.1988.9673918. st. clair j.j., garcía-peña g.e., woods r.w. & székely t. 2010. presence of mammalian predators decreases tolerance to human disturbance in a breeding shorebird. behavioral ecology 21, 1285–1292, doi: 10.1093/beheco/arq144. stutchbury b.j., tarof s.a., done t., gow e., kramer p.m., tautin j., fox j.w. & afanasyev v. 2009. tracking long-distance songbird migration by using geolocators. science 323, 896, doi: 10.1126/science.1166664. svazas s. & paulauskas a. 2006. identification of common snipe gallinago gallinago flyways in the western palearctic by analysis of ringing recoveries and genetic studies. in g.c. boere et al. (eds.): waterbirds around the world. pp. 522–523. edinburgh: the stationery office. svensson s. 2000. monitoring long term trends of bird populations in sweden. bird census news 13, 123–130. tapper s. 1992. game heritage. an ecological review from shooting and gamekeeping records. hampshire: game conservancy ltd. tavecchia g., pradel r., gossman f., bastat c., ferrand y. & lebreton j.-d. 2002. temporal variation in annual survival probability of the eurasian woodcock scolopax rusticola wintering in france. wildlife biology 8, 21–30, doi: 10.2981/wlb.2002.004. van gils j., wiersma p., kirwan g.m. & sharpe c.j. 2020. common snipe (gallinago gallinago), version 1.0. in j. del hoyo et al. (eds.): birds of the world. ithaca, ny: cornell lab of ornithology. doi: 10.2173/bow.comsni.01. visbeck m.h., hurrell j.w., polvani l. & cullen h.m. 2001. the north atlantic oscillation: past, present and future. proceedings of the national academy of sciences of the united states of america 98, 12876–12877, doi: 10.1073/pnas.231391598. weiser e.l., brown s.c., lanctot r.b., gates h.r., abraham k.f., bentzen r.l., bêty j., boldenow m.l., brook r.w., donnelly t.f. & english w.b. 2018. effects of environmental conditions on reproductive effort and nest success of arctic‐breeding shorebirds. ibis 160, 608–623, doi: 10.1111/ibi.12571. weiser e.l., lanctot r.b., brown s.c., gates h.r., bêty j., boldenow m.l., brook r.w., brown g.s., english w.b., flemming s.a. & franks s.e. 2020. annual adult survival drives trends in arctic-breeding shorebirds but knowledge gaps in other vital rates remain. the condor 122, article no. duaa026, doi: 10.1093/condor/duaa026. wentworth a. 2015. effect of different habitats on common snipe (gallinago gallinago) breeding abundance and nest survival in lowland iceland. msc thesis, nottingham trent university, nottingham. white g.c. & burnham k.p. 1999. program mark: survival estimate, ion from populations of marked animals. bird study 46, s120–s139, doi: 10.1080/00063659909477239. wood k.a., thorstensen s., lúðvíksson s.j., brides k. & petersen a. 2021. long‐term trends in the survival rates of adult female common eider somateria mollissima at three colonies in iceland. ibis 163, 671–683, doi: 10.1111/ibi.12893. wotherspoon s., sumner m. & lisovski s. 2016. twgeos: basic data processing for light‐level geolocation archival tags. version 0.0.1. accessed on the internet at https://github.com/slisovski/twgeos on 4 january 2022. żmihorski m., krupiński d., kotowska d., knape j., pärt t., obłoza p. & berg å. 2018. habitat characteristics associated with occupancy of declining waders in polish wet grasslands. agriculture, ecosystems & environment 251, 236–243, doi: 10.1016/j.agee.2017.09.033. can you hear me? impacts of underwater noise on communication space of adult, sub-adult and calf contact calls of endangered st. lawrence belugas (delphinapterus leucas) research article can you hear me? impacts of underwater noise on communication space of adult, sub-adult and calf contact calls of endangered st. lawrence belugas (delphinapterus leucas) valeria vergara,1 jason wood,2 véronique lesage,3 audra ames,4 marie-ana mikus1 & robert michaud5 1marine mammal conservation research program, ocean wise conservation association, vancouver, bc, canada 2smru consulting, vancouver, bc, canada 3fisheries and oceans canada, mont-joli, qc, canada 4fundación oceanogràfic de la comunitat valenciana, valencia, spain 5group for research and education on marine mammals, tadoussac, qc, canada abstract noise and anthropogenic disturbances from vessel traffic are an important threat to the recovery of the endangered st. lawrence estuary (sle) beluga population. the consequences of acoustic masking could be particularly adverse in the case of critical vocalizations that maintain contact between mothers and their dependent but mobile calves. this study models the communication range of adults, sub-adults and newborn beluga contact calls in the presence and absence of vessels in an important summering area for this population. ambient noise measurements, a composite beluga audiogram and apparent source levels of adult/sub-adult and newborn calls, informed the model. apparent source levels were estimated from received levels of contact calls produced by four individuals carrying digital acoustic tags in the sle, canada, and from received levels of calls recorded from two adults and a newborn calf at an aquarium, at known distances from a calibrated hydrophone. the median communication ranges were over 18 times larger for sle adult and sub-adult calls than for newborn calls, with a 57 and 53% reduction in range in the presence of vessel noise, respectively. for newborn calls, this results in a median range of 170 m in vessel noise. these first estimates of the communication range of beluga vocalizations with a known function suggest that masking of the quiet calls of newborns by anthropogenic noise could impair mother–calf contact. keywords communication masking; communication range; active space; vessel traffic; noise pollution; anthropogenic noise abbreviations aoa: angle of arrival aol: apparent output level asl: apparent source level dfo: fisheries and oceans canada dtag: digital acoustic recording tag fft: fast fourier transform algorithm iq: interquartile rms: root mean square sd: standard deviation sl: source level sle: st. lawrence estuary snr: signal-to-noise ratio spl: sound pressure level   citation: polar research 2021, 40, 5521, http://dx.doi.org/10.33265/polar.v40.5521 copyright: polar research 2021. © 2021 v. vergara et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 16 july 2021 competing interests and funding: the authors report no conflict of interest. this research has been supported by an aza conservation grants fund, earth rangers, fondation de la faune du québec, fisheries and oceans canada, and the sea world & busch gardens conservation fund. correspondence to: valeria vergara, marine mammal conservation research program, ocean wise conservation association, 845 avison way, vancouver, bc v6g 3e2, canada. e-mail: valeria.vergara@ocean.org this article is part of the special cluster beluga whales (delphinapterus leucas): knowledge from the wild, human care and tek, which has been funded by mystic aquarium, caff and the norwegian ministry of climate and environment. introduction the harmful effects of anthropogenic noise on marine organisms as diverse as fish (popper & hastings 2009), marine invertebrates (nedelec et al. 2014) and marine mammals (richardson et al. 1995; southall et al. 2007) are a worldwide problem directly linked to the increasing industrialization of the oceans (boyd et al. 2011). belugas (delphinapterus leucas) are one of the most acoustically active cetacean species, producing an extensive array of sounds for a variety of purposes, including maintaining contact and social communication, detecting prey and navigating (e.g., sjare & smith 1986a, b; vergara et al. 2010; vergara & mikus 2019). consequently, noise pollution from a number of sources (e.g., vessel traffic, seismic surveys, construction and dredging) represents a threat to belugas across much of their pan-arctic range, given its potential for disrupting their behaviour or impairing their ability to communicate effectively. the sle beluga population is endemic to canada and is reproductively and geographically isolated from other populations (brown gladden et al. 1999; postma 2017). this population was legally listed as endangered under canada’s species at risk act in 2016 because of its failure to recover from commercial and recreational hunting and recent decline (mosnier et al. 2015), ongoing habitat degradation and projected increases in threats (cosewic 2014; mosnier et al. 2015). in addition to a shortage of prey availability and high levels of contaminants, high noise levels and anthropogenic disturbance have been identified amongst the three main threats to the recovery of this endangered population (dfo 2017, 2020; williams et al. 2017). in much of the saguenay–st. lawrence seaway, belugas are exposed to noise from recreational and commercial vessel traffic (simard et al. 2010; mcquinn et al. 2011; gervaise et al. 2012; lesage, mcquinn et al. 2014). of the portion of the sle beluga population exposed to commercial marine traffic (15–53%), the vast majority (72–81%) are females with calves or juveniles (lesage, mcquinn et al. 2014). elevated numbers of beluga newborn calves have been found dead in the sle since 2008 (lesage, measures et al. 2014), accompanied by an increased mortality of adult females from peripartum complications (dystocia) since 2010 (lair et al. 2016). there are concerns that noise and disturbance may be one of the factors implicated in these unusually high mortalities (dfo 2014). the increased calf mortalities reported in 2010 and 2012 coincided with good weather conditions (favourable for boating) and peaks in recreational boating activity, with higher than usual co-occurrences between belugas and boats in the critical habitat of belugas during summer months (ménard et al. 2014). one of the potentially adverse effects of increases in anthropogenic noise levels is acoustic masking, the reduction of the effective range over which a communication signal can be detected and decoded by conspecifics (e.g., clark et al. 2009). this effective range is also known as the communication space of a signal, the area or volume around the vocalizing individual within which effective communication with conspecifics can be expected to occur (marten & marler 1977; clark et al. 2009). it is largely a function of a signal’s sl (the sound level at 1 m from the vocalizing animal on the acoustic axis [au 1993]), the levels of background noise, the transmission loss of the signal between the signaler and the receiver, the critical frequency bandwidth of the animal’s auditory filter (reichmuth 2012; erbe et al. 2016) and the hearing capabilities of the listener (brenowitz 1982; miller 2006; tervo et al. 2012). the effects of noise on communication space have been documented for a few high-frequency odontocete species (a functional hearing group [see southall et al. 2019]), including short-finned pilot whales (globicephala macrorhynchus; jensen, bejder, wahlberg, aguilar de soto et al. 2009), bottlenose dolphins (tursiops truncatus; jensen, bejder, wahlberg, aguilar de soto et al. 2009; jensen et al. 2012), killer whales (orcinus orca; bain & dahlheim 1994; au et al. 2004; miller 2006) and belugas (gervaise et al. 2012). the single beluga study that estimated the maximum communication range of a beluga signal in natural and variable ambient noise conditions used a hypothetical vocalization with an assumed central frequency of 2.5 khz (gervaise et al. 2012). although theoretical exercises with hypothetical signals are useful, evaluating the effects of noise on a commonly used signal of known acoustic characteristics and function would provide greater insight into beluga communication behaviour and the consequences of noise masking. despite many descriptions of the beluga whale’s extensive vocal repertoire (fish & mowbray 1962; sjare & smith 1986a; faucher 1988; angiel 1997; karlsen et al. 2002; belikov & bel’kovich 2006, 2008; panova et al. 2012), and some progress correlating call rates and broad call classes with general behavioural states (e.g., sjare & smith 1986b; belikov & bel’kovich 2003), little is known about the particular function of most beluga communication signals. those that function to establish or maintain contact between individuals are a notable exception, as much is currently known about these signals. a mounting body of work has established that belugas use broadband (200 hz–144 khz), long-duration (typically > 1s) pulsed contact calls for group cohesion during isolation (vergara et al. 2010; morisaka et al. 2013; mishima et al. 2015; panova et al. 2017; vergara & mikus 2019) and for mother–calf contact (vergara & barrett-lennard 2008; vergara et al. 2010; ames & vergara 2020). the broadband acoustic structure typical of beluga contact calls is shared with narwhals (monodon monoceros), a closely related species (shapiro 2006), and may have evolved to minimize masking by ambient noise in the arctic (vergara et al. 2010). this broadband structure differs markedly from the narrowband contact signals produced by delphinids, such as bottlenose dolphins (caldwell & caldwell 1965; review in janik & sayigh 2013), indo-pacific humpback dolphins (sousa chinensis; van parijs & corkeron 2001) and guiana dolphins (sotalia guianensis; duarte de figueiredo & simão 2009; lima & le pendu 2014). beluga contact calls can be complex—with a stereotyped component (often tonal or pulsed-tonal) in the lower frequencies (below 20 khz) overlapping the broadband pulse train—or simple, with only the pulse train but no overlapping component (vergara & mikus 2019). there is preliminary evidence that the stereotyped component of complex contact calls may function as a vocal signature, encoding identity at the individual or familial level (panova et al. 2017; vergara & mikus 2019). however, newborn beluga calves only produce simple pulse trains, developing their complex contact call as they age (vergara & barrett-lennard 2008). their initial pulse trains, the only call type that newborn belugas produce, are as broadband as the adult contact calls, but with less acoustic energy at high frequencies and lower pulse repetition rates compared to adult contact calls (vergara & barrett-lennard 2008; ames & vergara 2020). given that acoustic contact is critical in visually limited aquatic environments, the consequences of acoustic masking could be particularly adverse in the case of vocalizations that function to maintain contact between mothers and their dependent but precocious calves (kasuya 1995). yet, the specific impacts of noise on mother–calf contact signals have never been studied in belugas and have been studied in only a few other cetaceans, for example, north atlantic right whales (eubalaena glacialis; tennessen & parks 2016). here, we model the communication space of both adults/sub-adults and newborn beluga contact calls in the acoustic environment of baie sainte-marguerite, an area of high residency (lefebvre et al. 2012) for females and calves in the saguenay–st. lawrence marine park, where vessel traffic can be high at times during summer. we estimated the detection range of adult and calf contact calls under natural background noise conditions and modelled how this range changed in the presence of vessel noise. our findings shed light on the extent to which masking can compromise the mother–calf bond, which can inform species management plans both in the sle and throughout the beluga’s pan-arctic range. methods asls of beluga contact calls to evaluate the communication space of a signal, one would ideally need to know the sl of that signal, defined as its spl at a nominal distance of 1 m from the source, expressed in db re 1µpa at 1 m. when recordings at 1 m from the animal cannot be obtained, received spls are used to calculate the asls, defined as the back-calculated spls at 1 m distance from the sound source at an unknown angle from the acoustic axis (mohl et al. 2000; jensen, bejder, wahlberg & madsen 2009; wang et al. 2016). here, we used received levels of contact calls recorded from adult and sub-adult sle belugas carrying dtags (johnson & tyack 2003) to estimate asls (details below). in addition, to have a more complete understanding of the distribution of asls used by adult and newborn belugas when they emit contact calls, we estimated contact call asls from recordings made at an aquarium (oceanogràfic, valencia, spain) at known distances from a calibrated hydrophone (specifications provided in the following sections). in all cases, the broadband asl estimates integrated calls from 500 hz to 100 khz, to cover the majority of energy contained in beluga broadband contact calls while also matching the frequency response and sampling rates of the acoustic recorders used in this study. the asl estimates were calculated both in broadband (from 500 hz to 100 khz) for comparison with other studies as well as in 1/12 octave bands for our communication range estimates (see sections below on rationale for 1/12 octaves and methods for communication range estimates). the contact call data sets and asl estimation are described below, and representative spectrograms are provided in fig. 1. fig. 1 representative spectrograms of the contact call data sets used for our asl estimates (fft at 2048 points with a 50% overlap, hann window): (a) sle (dlt18003), (b) oceanogràfic aquarium female, (c) oceanogràfic aquarium male, (d) oceanogràfic aquarium three-day-old calf. sle adult and sub-adult contact calls. asls were estimated from 53 contact calls identified in recordings from two adults (20 and 13 calls) and two sub-adults (≥ four years old; 14 and six calls) carrying dtags. the sex of the animals was unknown, although the two adults were likely males, as inferred from the composition of their groups (predominantly large adults, no calves). the dtags were deployed during the summers of 2018 and 2019, from an 8 m research vessel, using a handheld carbon fibre pole to attach the tag to a whale via suction cups (fig. 2). the dtags record sounds continuously through two hydrophones positioned 43 mm apart, at a sampling rate of 240 khz per channel. only one individual was tagged at a time. the dtags were equipped with a vhf beacon that facilitated following the tagged whale and tracking and recovering the device when it released. the recording period lasted 4–13.5 hours (until the tag released), and focal follows of the tagged individuals were performed when possible. each time the tagged whale was spotted during a surfacing sequence, the observer noted whether the animal was alone or in association with others. fig. 2 dtag deployment on a sub-adult beluga, using a handheld carbon fibre pole, within 1 m of the blowhole. to identify contact calls in recordings of tagged whales, we analysed a total of 93 hours and 22 minutes of acoustic data from 22 tagging events. contact calls were identified visually (following vergara & mikus 2019) using raven pro 1.5 software (cornell lab of ornithology) and adhered to the following criteria: (a) produced in series (i.e., two or more of the same calls within 10 seconds), with a series appearing more than once in the recording; (b) stereotyped (i.e., signals in a repertoire that have little variability in acoustic parameters between utterances); (c) little fluctuation in amplitude within a series (as large fluctuations could indicate another animal swimming at various distances and orientations from the tagged whales); (d) predominant contact call type if more than one type was identified in the recording and (e) snrs of more than 10 db, to exclude faint contact calls from distant animals (see saddler et al. 2017). the snr was calculated as the difference between the rms ‘inband power’ of the signal in the frequency band 500 hz to 100 khz, which contains most of the sound of interest for the broadband contact calls, and the inband power of the ambient noise period immediately preceding or following the signal (in the same frequency range and for a duration as close as possible to the signal). once contact call series were identified in dtags, those produced by the tagged beluga were further distinguished from those of nearby whales based on the aoa (johnson et al. 2006). this was calculated with the following formula from johnson et al. (2006): aoa = sin–1(τc/d), where c is the speed of sound in seawater, d is the hydrophone separation (43 mm) and τ is the time delay between the two hydrophone signals, measured by cross-correlation. only contact calls with consistent aoas that were ± 10 degrees from the mean aoa were considered as being produced by the tagged beluga (jensen et al. 2011; perez et al. 2017). this condition was met by contact call series in four of the dtags (n = 53 contact calls, mean snr 24 ± 7 db). for three of the four dtag carriers for which identified contact calls met the aoa condition, visual observations and the scarcity of other calls in the recordings indicated a lack of association with other individuals at the time of contact call production. we calculated the aols of the identified contact calls, defined as the received levels on the dtag in a fixed but off-axis position on the body of the whale (madsen et al. 2005; jensen 2020). odontocetes generate sound below the blowhole, when air passes through two structural complexes formed by a fatty bursa embedded in a pair of phonic lips, causing them to open and slap together, creating vibrations (cranford et al. 1996). given that the dtags were placed each time within 1 m of the blowhole but not exactly at 1 m (fig. 2), and always behind rather than in front of the sound generating structure and thus not in the path of the forward-directed sound beam (madsen et al. 2005), we considered the aols as simple approximations of the asls for our model. the dtag hydrophone channel with the higher amplitude was used for measurements of aols. oceanogràfic adult contact calls. we calculated asls for 16 contact calls from an adult female, yulka (n = 10), and an adult male, kairo (n = 6), recorded in isolation at oceanogràfic, an aquarium in valencia (spain), at known distances from the hydrophone (ranging 12–15 m), with the animals facing the hydrophone or at a slight angle to it. we used a calibrated iclisten ocean sonics digital hydrophone sampling at a rate of 256 khz (24-bit resolution). the hydrophone was in a permanent position in the pool, at a depth of 1 m. we used cylindrical spreading to approximate transmission loss, as follows: rl + 10*log10 (d), whereby rl is the received level and d is the distance from the hydrophone. oceanogràfic newborn contact calls. we used ames & vergara’s (2020) asls from 65 broadband pulse trains produced by a male beluga calf, kylu (born at oceanogràfic on 15 november 2016), during his first month of life (days 2–28). the same digital sampling set-up as that described for the oceanogràfic adult calls was used. the vocalizations were assigned to the calf when he was isolated in one of the pools or if they coincided with the emission of bubble streams, a methodology commonly used in vocal development studies of odontocetes (mccowann & reiss 1995; bojanowski et al. 2000; killebrew et al. 2001; mello & amundin 2005; morisaka, shinohara & taki 2005; fripp & tyack 2008; vergara & barrett-lennard 2008; bowles et al. 2015). the calf produced broadband pulse trains almost exclusively during his first month, presumably rudimentary contact calls (ames & vergara 2020). ames & vergara subsampled those pulse trains for which the distance of the calf to the hydrophone during sound production was known (distances ranged 1.5–17 m), and during which the calf was either facing the hydrophone or at a slight angle to it, but not facing completely away from the hydrophone (all 180° angle orientations were discarded). cylindrical spreading was used to approximate transmission loss, in the same way as for the aquarium adults, described above. critical bandwidth and audiogram of receiver. we used the beluga audiogram from erbe et al. (2016) based on measured hearing thresholds pooled from all individuals tested for both aep and behavioural methods (white et al. 1978; awbrey et al. 1988; johnson et al. 1989; popov & supin 1990; erbe & farmer 1998; klishin et al. 2000; ridgway et al. 2001; finneran et al. 2002; finneran et al. 2005; mooney et al. 2008; castellote et al. 2014). the critical bandwidth measures the width of the auditory filter within which masking can occur. noise effectively masks a signal when it is within a critical bandwidth of frequency around the desired signal. for belugas, 1/12 of an octave is likely the best current estimate of the noise-masking potential (erbe 2000). ambient noise recordings ambient noise recordings took place at baie sainte-marguerite, a small delta at the confluence of the saguenay and sainte-marguerite rivers, 12 nautical miles upstream from the mouth of the saguenay fjord, in the sle, canada (fig. 3). this bay is an area of high residency for female belugas and their calves, used for socialization and resting and where females care for their young (lefebvre et al. 2012; dfo 2018). the depth is 118 m in the centre of the saguenay at its deepest channel, decreasing to 10 m closer to the head of the sainte marguerite river. only 1.5 km separate the bay’s intertidal zone from the opposite shore of the saguenay river, and this, in addition to the steep bathymetry of the area, means that any vessel entering the bay or transiting the river, ensonifies the whole area from shore to shore. fig. 3 the sle study area, canada, indicating the location of the hydrophone in baie sainte-marguerite, an area of high residency for sle beluga females and calves, where ambient noise was recorded in this study (numbers indicate depth in metres). we used two factory-calibrated passive acoustic monitoring devices. a soundtrap hf300 (ocean instruments, new zealand) with a flat frequency response from 20 hz to 150 khz (± 3 db), –172.7 db re 1v/µpa sensitivity, 16-bit resolution and a sampling rate of 288 khz was deployed at a depth of 15–20 m. the device recorded continuously during the three following periods in the summer of 2017: 24 july to 29 july, 31 july to 8 august and 9 august to 18 august, for a total of 23 days of recordings. the soundtrap was tethered to our observation platform (described below) with a sink line, moored to an anchor and attached to a buoy to keep it suspended just above the riverbed. in addition, on days when we accessed the observation tower, we deployed a calibrated iclisten hf hydrophone (ocean sonics), with a frequency response of 10–200 khz, 24-bit resolution and a sampling rate of 256 khz. this device also streamed sound in real time through a speaker so that we could listen to the belugas while conducting visual observations. visual observations we conducted visual observations from a 6-m high observation tower, with a 1.5 × 3 m platform, erected during the spring tide window at the mouth of the sainte-marguerite river, at 48°15′2.83″n 69°58′0.83″w. except for the periods coinciding with very low tides, the tower was surrounded by water and the whales often swam near it, undisturbed by our presence. we used a fixed two-minute interval scan sampling technique (martin & bateson 2007) to document vessel data (number and type of boats running during the two-minute interval, and distance category from the hydrophone). every 30 minutes, we also documented the presence or absence of belugas in the bay, number of animals in the herd and herd composition. herd composition and contact call usage in order to examine the extent of contact call usage in the repertoire of sle belugas and evaluate whether this call type is favoured in herds of females and calves, we paired data on contact call production and herd composition. we analysed 24.5 hours of recordings obtained on 22 different days of visual observations of beluga herds in baie sainte-marguerite in 2017 and 2018. herd composition was noted for all herd encounters and divided into the following two general categories: (a) all adults and sub-adults, (b) adults, sub-adults and calves and/or yearlings. contact calls were identified in spectrograms using raven pro 1.5 (cornell lab of ornithology), following vergara & mikus (2019). a chi-square test of homogeneity was conducted to test the difference in the proportion of contact call usage in the two types of herd using spss statistics software (laerd statistics 2016). noise profile analysis we used matlab r2017b and scripts modified from merchant et al. (2015) to analyse 23 days of soundtrap data from the three contiguous deployments, splitting the wav files into one-minute duration files and measuring power spectral density levels for each one-minute file with an fft window size that matched the sampling rate (288 000 samples), a 50% overlap and welch’s averaging (merchant et al. 2015). this is the first step required to model the communication range of adult and calf contact calls under various noise level conditions in baie sainte-marguerite. we manually reviewed 241 hours and 20 minutes of soundtrap recordings while visualizing them on spectrograms. this amounts to about 10 of the 23 days of deployment, including 12.3 daytime periods (05:30 to 20:00) and 6.6 nighttime periods (20:00 to 05:30). we cross-checked the recordings with our visual notes (for the daytime periods) and verified potential vessel and/or beluga presence in the bay by visual and aural inspection of the audio recordings, in order to have a sample of time periods with (1) natural ambient noise (neither boat noise nor whale sounds), (2) boats (but no whales), (3) whales (but no boats) and (4) both boats and whale sounds. for this paper, we considered one or more boats running up or down the river within 2 km of the hydrophone as ‘boats present.’ familiarizing ourselves with boat noise confirmed by visuals to be within 2 km of the hydrophone during daytime periods enabled us to approximate the same distance when relying exclusively on spectrograms for nighttime periods (note that vessel noise was very infrequent at night; see results). communication range estimates the communication range of each contact call was estimated as the maximum range at which the signal is still audible (snr > 0 db) by a conspecific in at least one of the 1/12 octave bands analysed, after accounting for transmission loss (adapted from miller 2006 and wang et al. 2016). for comparison, we also estimated the detection range within which all 1/12 octave bands in the broadband calls (integrated from 500 hz to 100 khz), and half of the 1/12 octave bands, would still be audible. to obtain estimates of the communication space of beluga contact calls, we used als estimations of the contact calls, transmission loss, our measurements of ambient noise under no-boat conditions and when boats were present in baie sainte marguerite, and the beluga audiogram from erbe et al. (2016). for the propagation of the beluga contact calls, we used the approximate spreading loss coefficient for the saguenay river reported in fig. 8 of mcquinn et al. (2011), ca. 18 db. frequency dependent absorption was also included in our calculations. in each 1/12 octave band and at each distance, either the beluga hearing curve or the noise level, whichever was greater, was subtracted from the estimated beluga contact call received level in that 1/12 octave band. this resulted in a signal excess, or the number of db that the contact call would be above the noise level or hearing curve at that distance for that 1/12 octave band. the model considered the distance at which the signal excess reached zero in all 1/12 octave bands analysed (see erbe [2000] for measurements of beluga hearing thresholds in noise that corroborate fletcher’s equal power assumption of snr = 0 db). for each contact call, a matlab code calculated signal excess for each one-minute noise file for both ‘no boat’ and ‘boat’ conditions (when no belugas were present, to avoid conspecific masking as a confounding factor), to generate distribution curves of all possible communication ranges in all noise scenarios in baie sainte-marguerite. in permutating every contact call and every one-minute noise file, the model took into account all of the variability in our data. for example, to estimate communication ranges for the dtag calls (n = 53) in the presence of boat noise (2220 minutes with boats and no whales), the model ran 117 660 permutations (2220*53), and to estimate range in quieter conditions (9978 minutes with no boats and no whales), the model ran 528 834 permutations (9978*53). results herd composition and contact call usage of the 22 different herd encounters in baie sainte-marguerite (on 22 different days), 12 consisted of adults, sub-adults and newborn calves (mean herd size 39 ± 17), one consisted of adults, sub-adults and yearlings (herd size 30) and nine had only large adults (often males) and sub-adults, with neither newborns nor yearlings (mean herd size 18 ± 10 individuals). a total of 26 753 calls emitted during these 22 herd encounters were categorized into ‘contact call’ or ‘other type’ for herds with versus without newborns/yearlings. there was a statistically significant difference between the proportion of contact calls produced by herds with calves or yearlings compared to herds comprised of older individuals ( χ 2(1) = 97.53, p < 0.001), with contact calls being used significantly more often in herds with newborns and/or yearlings (11.8%) than in adult/sub-adult herds (6%). characteristics of the baie sainte-marguerite soundscape the leq (equivalent rms sound level) showed some short duration but high-amplitude events when integrated across the 23 days of data (fig. 4). the bimodal distribution between 100 hz and 10 khz may be driven by beluga calls or boat noise. figure 5 provides the broadband noise cumulative probability plots for 241 hours of recordings that were manually verified and split (minute by minute) into the four pre-defined categories. when belugas were present in the bay, vessel noise emanating from one or more vessels was confirmed 23% of the time (520/2271 minutes). in total, vessel noise was confirmed 19% of the time (2744/14 479 minutes). splitting the manually verified recordings into daytime and nighttime hours (sunrise 05:30 to sunset 20:00), vessel noise occurred during 24% of the daytime recordings (2540/10 729 minutes) and 5% of the nighttime recordings (204/3751 minutes). fig. 4 power spectral density levels over the 23-day recording period at baie sainte-marguerite. spd is the spectral probability density. l5, l25, etc. are exceedance levels (i.e., l5 means sound levels exceed this 5% of the time). leq is the rms level. wenz lines are the limits of prevailing noise (wenz 1962). fig. 5 broadband sound pressure level cumulative probability plots for the four manually verified periods for 241.33 hours of recordings. broadband asls of beluga contact calls adult and sub-adult contact calls. the sample of 53 complex contact calls recorded from temporarily tagged adult and sub-adult belugas in the sle had a mean asl of 150.1 ± 7.5 db re 1 µpa at 1 m and a median of 150.3 db re 1 µpa at 1 m, slightly louder than the asls for the sample of 16 complex contact calls produced by the two adult belugas housed at oceanogràfic, with a mean of 146.8 ± 5.8 db re 1 µpa at 1 m and a median of 147.9 db re 1 µpa at 1 m. table 1 lists the asls of calls produced by each individual, in addition to the peak frequencies and duration of the calls.   table 1 beluga contact call data sets, peak frequency, duration (delta time) and asls. all calls were broadband and had a maximum frequency equal to the nyquist frequency (120–128 khz). data set n contact call type peak frequency (khz) delta time (s) asl (db re 1 µpa at 1 m) mean ± sd median mean ± sd median mean ± sd median sle (dtags) dlt18002 (sub-adult) 6 complex 2.1 ± 1.5 2.1 0.9 ± 0.2 0.9 151.4 ± 1.3 150.8 dlt18003 (sub-adult) 14 complex 7.4 ± 4.2 8.4 1.2 ± 0.5 1.4 140.2 ± 1.1. 140.1 dlt18011 (adult) 13 complex 5.3 ± 2.3 4.1 0.7 ± 0.04 0.7 150.2 ± 2.4 150.2 dlt19008 (adult) 20 complex 5.1 ± 0.7 4.8 1.0 ± 0.3 1.0 156.6 ± 5.6 157.7 aquarium adult female 13 complex 12.2 ± 1.1 12.2 1.1 ± 0.1 1.2 144.0 ± 4.6 144.6 adult male 6 complex 11.3 ± 1.6 12.0 1.4 ± 0.2 1.4 151.6 ± 4.2 150.6 newborn calf 65 simple 5.6 ± 8.6 3.9 0.7 ± 0.4 0.7 126 ± 8.4a 127.0a amean and median asl for the newborn calf from ames & vergara (2020). newborn calls. the pulse trains emitted by the newborn beluga calf during its first month of life had a mean asl of 126.7 ± 8.4 db re 1 µpa at 1 m and a median of 127 db re 1 µpa at 1 m, about 20 db quieter than the asls from adult contact calls in the same aquarium (table 1). a detailed study of this calf’s vocal development showed a significant increase of asls with age (ames & vergara 2020), with a 12 db increase in mean asl after the first week of life: asl increased from an average of 120 ± 5.8 db re 1 µpa at 1 m and a median of 121.1 db re 1 µpa at 1 m from days 2 to 7 to an average asl of 132.7 ± 5.1 db re 1 µpa at 1 m and a median of 132.8 db re 1 µpa at 1 m from days 14 to 28. communication range adult and sub-adult contact calls. the estimated communication range of sle adult/sub-adult beluga broadband contact calls in the absence of boat noise had a median of 6.7 km, based on the 1/12th octave band audible to the greatest distance (iq range 3.4–20.9 km, fig. 6, table 2). in a noisy environment, with levels like those recorded in baie sainte-marguerite during summer, the estimated communication distance for adult and sub-adult contact calls could be reduced by 57%, to a median range of 2.9 km, although this distance could be as short as 1.2 km (table 2). these ranges were larger than the modelled communication ranges for the aquarium female’s contact calls, which had a median of 2.3 km (iq range 1.7–3.9 km) in the absence of boats, with a potential 36% reduction in range in the presence of boat noise.   table 2 median and interquartile ranges for estimates of communication range of beluga contact calls under ‘no boats’ and ‘boats’ noise conditions, indicating percentage reduction in range under noise levels like those recorded when boats were present in baie sainte marguerite. median and interquartile ranges for the 1/12 octave band centre frequency of maximum distance are also presented. call data set noise environment max distance (m) frequency of max distance (hz) median iq range % reduction median iq range adults/sub-adults, dtags sle no boats 6680 3370–20 990 57 4870 4340–6494 boats 2890 1220–8900 4870 4870–9173 adult female, aquarium no boats 2330 1730–3780 36 11 548 10 292–13 725 boats 1490 860–2430 13 725 11 548–13 725 newborn, aquarium no boats 360 140–1070 53 3255 2738–4097 boats 170 60–390 3255 1223–36 517 fig. 6 histograms showing distribution curves of modelled communication range of adult/sub-adult beluga contact calls produced by belugas carrying dtags (sle). (a) maximum communication distances under ‘no boats’ (top) and ‘boats’ (bottom) scenarios. (b) 1/12 octave centre frequencies of maximum communication distances under ‘no boats’ (top) and ‘boats’ (bottom) scenarios. the count on the y axis is the number of model iterations for each combination of one call and one-minute noise file that falls in a specific distance or frequency bin. for comparison, the median distance at which all 1/12 octave bands in the broadband calls emitted by wild belugas would be audible by a conspecific was much smaller (given the poor transmission of the very high-frequency components of these broadband calls). this was the case both in the absence of boats (40 m) and in their presence (20 m), still showing a 50% reduction. the range at which half of the 1/12th octave bands reached an snr > 0db was reduced by 39% with boats present (410–250 m). the 1/12th octave frequency bands that were audible for the longest distances for the sle calls had a median of 4.9 khz both in quiet and noisy conditions. this is near the frequency range of the putative signature element of the sle calls, which had a median peak frequency of 4.8 khz (n = 53). to illustrate the reduction in range in a single call for each one of the 1/12 octave bands analysed (centre frequencies 487–97 163 hz), we selected the contact call from our sle dtag data set that had an asl equalling the median asl of the set (150.28 db re 1 µpa at 1 m). in the absence of boat noise, most 1/12 octave bands between 2 and 10 khz would be audible to a conspecific between 1 and 3 km away (fig. 7). the centre frequency of the 1/12 octave band that extends the furthest is 4.8 khz (reaching 3.5 km). in the presence of boat noise, none of the 1/12 octave bands would be audible beyond 700 m for this particular call. fig. 7 maximum communication range of each 1/12 octave band of a representative adult/sub-adult contact call in our data set (the call with the median source level) under ‘no boats’ (a) and boats (b) conditions. for each 1/12 octave band and at each distance, we subtracted the beluga hearing curve or the noise level, whichever was greater, from the received level. the ‘signal excess’ is the number of db re 1 µpa that the beluga call is above the noise level or hearing curve. newborn calls. the median communication range for newborn beluga calls was only 360 m in the absence of boat noise (iq range 140–1070 m) and might be reduced by 53%, to a median of 170 m (iq range 60–390 m) in the presence of boat noise. the 1/12 octave frequency bands that were audible at the furthest distances had a median of 3.3 khz in the absence of boats, and 3.6 khz in boat noise (fig. 8, table 2). fig. 8 histograms showing distribution curves of modelled maximum communication ranges using calls recorded from a newborn beluga at oceanogràfic (valencia). (a) maximum communication distances under (top) ‘no boats’ and (bottom) ‘boats’ scenarios. (b) 1/12 octave centre frequencies of maximum communication distances under (top) ‘no boats’ and (bottom) ‘boats’ scenarios. the count on the y axis is the number of model iterations for each combination of one call and one-minute noise file that falls in a specific distance or frequency bin. using the newborn call that had an sl equaling the median asl of the set (127 db re 1 µpa at 1 m, day 5 of life) to illustrate the potential reduction in range for each of the 1/12 octave bands, the maximum audible distance in the absence of boats would be 300 m, and less than 150 m in boat noise (fig. 9). fig. 9 maximum communication range of each 1/12 octave band of a representative newborn beluga call in our data set (the call with the median source level, day 5 of life), under (a) ‘no boats’ and (b) ‘boats’ noise conditions. for each 1/12 octave band and at each distance, we subtracted the beluga hearing curve or the noise level, whichever was greater, from the received level. the ‘signal excess’ is the number of db re 1 µpa that the beluga call is above the noise level or hearing curve. discussion the mother–calf bond in belugas and other delphinids is maintained primarily through vision at close ranges (krasnova et al. 2009; karenina et al. 2010; hill et al. 2017) and acoustically when calves venture beyond a few metres, where visual contact becomes ineffective (e.g., smolker et al. 1993). the present study provides the first data on asls and the communication range of contact calls in captive and wild belugas of different age classes. previous studies had established that these calls are used between mothers and calves to regain or maintain contact with one another, and also by adults and juveniles for group cohesion (vergara & barrett-lennard 2008; vergara et al. 2010), and the current study further confirms that these calls are used preferentially in herds with newborns. despite the unavoidable shortcomings of all modelling in characterizing real world complexity (e.g., tennessen & parks 2016), our study illustrates how changing levels of underwater noise affect the communication range of adult/sub-adult and infant belugas and demonstrates particularly strong masking effects for the underdeveloped calls of newborns. sl measurements for aquatic species are difficult to obtain because the precise location of the vocalizing animals cannot always be determined accurately (casey et al. 2016). the mean broadband asls of adult and sub-adult beluga contact calls reported here are within the range of slrms of odontocete sounds reported in the literature, such as indo-pacific humpback dolphins (138.5 ± 6.8 and 137.2 ± 7.0 db re 1 µpa depending on location [wang et al. 2016]), killer whales (155.3 ± 6.5 db re 1 µpa, holt et al. 2011), blainville’s beaked whales (mesoplodon densirostris; range 123–149 db re 1µpa [aguilar de soto et al. 2012]), bottlenose dolphins (158 ± 0.6 db re 1µpa [janik 2000]; 146.7 ± 6.2 db re 1µpa [jensen et al. 2012]; median 138 db re 1µpa [frankel et al. 2014]), spotted dolphins (stenella frontalis; median 138 db re 1µpa [frankel et al. 2014]) and white-beaked dolphins (lagenorhynchus albirostris; 148 ± 12 db re 1µpa or 139 ± 12 db re 1µpa, depending on method [rasmussen et al. 2006]). the only other study that documented sls of beluga calls looked at narrow-band tonal signals rather than broadband pulsed calls and found a mean slrms of 143.8 ± 6.7db re 1 µpa at 1 m, for a sample of 52 whistles with a dominant frequency between 1.5 and 5 khz (le bot et al. 2016). our modelled median communication ranges for adult and sub-adult beluga calls in the ambient noise levels of baie sainte-marguerite indicate a potential reduction to less than half the distance (57% reduction) in the presence of boats. the only other published estimation of the communication range of a wild beluga call used a hypothetical narrowband beluga signal in natural ambient noise conditions and estimated a range of 4.5 km with a potential reduction in noise to 1.5 km 50% of the time and to 0.6 km 25% of the time in the high traffic area at the mouth of the saguenay fjord (gervaise et al. 2012). the detection range of individual vocalizations is greatly influenced by their sls. we have shown here that newborn calves produce calls with asls that are on average 22 db lower than adults or sub-adults, and that their calls are particularly weak during the first week of life. this corroborates previous studies that describe the initial pulse trains produced by a male beluga newborn calf at the vancouver aquarium as ‘barely audible’ low-energy calls (vergara & barrett-lennard 2008: 129), and those produced by two additional captive calves at the same aquarium as having low acoustic energy and slower pulse repetition rates relative to later calls (vergara 2011). our asl estimates translate into a more restricted communication range (i.e., < 500 m) for newborn beluga calls that can be nearly 5% that of adults and sub-adults. the modelled median communication range for the mother of this calf, which was about a third that of the sle whales in quiet conditions (commensurate with the slightly lower asls of her calls), was still over six times the range of the soft calf calls. recent studies of calls produced by mother–calf pairs in mysticetes—humpback whales (megaptera novaeangliae; videsen et al. 2017), southern right whales (eubalaena australis; nielsen et al. 2019) and north atlantic right whales (eubalaena glacialis; parks et al. 2019)—have also reported low output energy and small communication spaces, although this applied to both members of the pair, not only to the calves. in these studies, the importance of low-amplitude signals to maintain contact between mothers and calves is proposed as a cryptic strategy to reduce the risk of attracting aggressive male escorts among humpback whales or, for humpback, southern right and north atlantic right whales, predators like killer whales and white sharks (carcharodon carcharias). belugas are also known to be preyed on by killer whales in various populations (reeves & mitchell 1988; frost et al. 1992; shelden et al. 2003) and to use estuaries as a strategy to avoid such predation (michaud 2005). aggression by adult males towards newborn calves has been observed (michaud, unpubl. data). in russia’s white sea, beluga mothers tend to position themselves between their calves and approaching males, and beluga mother–calf pairs show evasive behaviour and leave the main group when males approach (krasnova et al. 2006). in view of this, it is possible that the quiet calls of beluga newborn calves evolved as a cryptic strategy. the small communication space of newborn beluga calls makes them particularly sensitive to increases in underwater noise, which can reduce a newborn call to a few tens of metres. the implications of these results for the ability of mothers and newborns to reunite when separated depend on the relative proximity maintained between mother and infant, a distance that changes as the calf acquires diving and social skills. many cetacean calves remain in close proximity (within visual contact) to their mothers during the first few weeks of life, for example, bottlenose dolphins (mann & smuts 1998, 1999), humpback whales (szabo & duffus 2008) and southern right whales (taber & thomas 1982). captive beluga calves initiate separations from their mothers almost immediately after birth, but these separations are limited to short distances of 1–5 m (hill 2009). wild beluga calves in the white sea stay mostly in contact with their mother during the first days of life, and mothers impede all observed newborn attempts to swim farther than 2 m (krasnova et al. 2009). separations of only 2–3 m begin on day 4 of life and can last over 10 seconds by day 10 (krasnova et al. 2006). these swimming excursions away from the mother increase in frequency at 7–10 days of age, and, by two weeks of age, beluga calves can leave their mothers briefly and form transient associations with other calves and yearlings in the aggregation (krasnova et al. 2006, 2009). how beluga mother–calf pairs use contact calls during separations and reunions, and which member of the pair might be responsible for initiating reunions is, however, unknown. in bottlenose dolphins, one study reported that infants produced the majority of the whistles during mother–calf separation contexts, but the study only analysed data for infants older than four months (smolker et al. 1993). a follow-up study with a single mother–calf pair under human care showed that the maternal signature whistle is in fact important and is consistently used for mother–calf reunions; albeit data on neonates were not available in this study either (king et al. 2016). even if beluga newborns in their first few days of life do not separate from their mothers beyond distances that would compromise acoustic and visual contacts, unintentional separations to further distances may occur. these may be more likely during disturbance events. for example, mothers in pelagic dolphin species show flight behaviour during tuna purse-seine sets that may induce involuntary separations from their dependent calves that could increase the risk of mortality, especially for young animals under a year in age (noren & edwards 2007). this is because calves following fleeing mothers simply fall too far behind due to the loss of the hydrodynamic connection with their mothers, or ‘drafting’ (weihs 2004). maternal flight responses that do not deviate from the fleeing behaviour of other adults, even at the expense of the calf, have also been documented in terrestrial herd mammals. barren-ground caribou (rangifer tarandus groenlandicus) mothers run with the herd during perceived or real threats, causing temporary or permanent separations from their young (lent 1966). beluga females with calves in the white sea are the first to flee in response to danger (krasnova et al. 2009). it is not implausible that in the sle, involuntary separations may similarly occur in the face of some disturbances, and that noise may interfere with mother–calf reunions after such separations. a beluga newborn would conceivably hear the mother but may be too young to orient to her and find her, and the mother may simply not hear the calf, given the very short communication range of newborn calls in noise. the nature of the disturbances that could elicit flight reactions may depend on the level of habituation of belugas to such disturbances. in baie sainte-marguerite, cargo ships may degrade the acoustic habitat but not cause a startle response, whereas recreational vessels approaching belugas at high speeds (against current regulations, but repeatedly observed by some of the authors) may elicit evasive behaviour. the low asls of newborn calls also have important implications regarding a newborn’s ability to compensate for noise. marine mammals use a number of compensation strategies to improve signal detection in noisy environments, including longer calls, louder calls, increasing call rate, shifting the frequency of the signal outside the noise band, switching call types and waiting to call until noise decreases (see tyack & janik 2013, for review). evidence of these compensation strategies in odontocetes, including killer whales (wieland et al. 2009; holt et al. 2011), bottlenose dolphins (au et al. 1982; buckstaff 2004) and indo-pacific bottlenose dolphins (morisaka, shinohara, nakahara et al. 2005), as well as belugas, is mounting. it is well known that belugas modify their vocal production in response to noise. for example, sle belugas shift the mean frequencies of their calls upward (from 3.6 khz to 5.2–8.8 khz) and increase the repetition rate of their whistles in the presence of small vessel and ferry noise (lesage et al. 1999). they also increase the amplitude of their calls in response to noise, a mechanism known as the lombard effect (scheifele et al. 2005). mackenzie river estuary belugas may reduce their vocal production in response to vessel noise (halliday et al. 2019). belugas are also able to adapt their echolocation strategy in noisy environments by modifying the amplitude, spectral and temporal parameters of echolocation clicks (au et al. 1985). however, beluga neonates may not be able to resort to these compensatory strategies. pulse trains (rudimentary contact calls) are the only call type that they produce, expanding their repertoire as they age (vergara & barrett-lennard 2008), and days-old calves may be physiologically unable to increase call amplitude or shift the peak energy of their pulse trains to higher frequencies (see ames & vergara 2020). ames & vergara (2020) showed that the peak frequencies of the calf’s calls increased significantly over his first year of life and suggested that as belugas gain the ability to increase air pressure with age (which relates to an increase in sl [cranford et al. 2000]), they may also gain the capacity to increase acoustic energy at higher frequencies (see madsen et al. [2013] for correlation between sl and centre frequency). the farthest range of adult and sub-adult calls coincided with the frequencies of the stereotyped putative signature elements of contact calls (vergara & mikus 2019), which may have evolved for effective detection by conspecifics in the noisy and reverberant icy environment of the arctic. the fact that beluga newborns only produce rudimentary, simple contact calls (vergara & barrett-lennard 2008; ames & vergara 2020), which lack the overlapping tonal or pulsed tonal element of complex contact calls, may also explain their small communication ranges. an important consideration is that we estimated communication range as the maximum distance at which the signal would still be audible by a conspecific in at least one of the 1/12 octave bands analysed, not in all 1/12 bands. this is useful to understand how the various critical bands are affected differently by noise, and which frequency bands would remain audible at particular distances. however, it may be important for a conspecific to receive closer to the full signal to be able to decode it (see brumm & slabbekoorn 2005). when we modelled the range within which half, and all, 1/12 octave bands in the broadband calls would still be audible, the detection distances were, of course, considerably smaller, as these scenarios must take into account some or all of those very high-frequency bands that do not travel far in the first place, given the high absorption of high-frequency sounds. therefore, the extent to which our communication range estimates reflect how far a calf would be able to recognize its mother acoustically by receiving and decoding her contact call is unknown. for a particular signal to confer an advantage to an individual (for example, to maintain contact with known individuals), detection alone may not be enough. a beluga would have to recognize and localize the call and then discriminate among signal types and possibly individual callers. moving from detecting sounds in noise, to signal recognition and discrimination, to effective communication requires progressively higher snrs (erbe 2012; reichmuth 2012). there is evidence from birds, for example, budgerigars (melopsittacus undulatus) and zebra finches (taeniopygia guttata; lohr et al. 2003), that call discrimination is more difficult than call detection and has higher masked thresholds at a given level of noise (lohr et al. 2003). in critical situations, masking-induced errors in the interpretation of signals by the receiver might incur biological costs. to date, there are no cetacean studies on the effect of acoustic masking on the recognition and discrimination of sounds. future masking models would more closely approach real-world scenarios if they considered these biologically significant processes. our study, therefore, suffers from a number of evident shortcomings. the question of how many of the 1/12 octave bands need to be audible for a call to not only just be detectable but also recognizable by conspecifics, remains. our asl estimations are, of course, not precise. since the dtags are located on an off-axis position on the body of the whale, and behind the sound-generating structures (and thus not in the path of the acoustic beam of the whale), the asls estimated from the dtags aols are likely lower than true on-axis sls (see madsen et al. 2005; johnson et al. 2006). furthermore, our asl estimates could not account for the directionality of contact calls, a factor known to affect sl among hawaiian spinner dolphins (stenella longirostris; lammers et al. 2003) and bottlenose dolphins (branstetter et al. 2012). our communication range modelling did not include noise profile data obtained when belugas were present in the bay, so conspecific masking is not factored in our estimates. considerations such as the temporal aspects of the vessel noise (frequency and duration of vessel transits through an area) and the effects of mitigation measures such as speed reduction were not examined in this paper. finally, and perhaps of most relevance to the rationale behind this study, there is still some uncertainty about how often beluga calves separate from their mothers during the first month of life and to what distances and how long those separations last, especially in the sle population. this information would be invaluable combined with data on the duration of loud masking events. conclusion although our estimates should be treated with caution, they are, to our knowledge, the only estimates of asls and communication range of beluga calls produced by different age classes and with a known critical function, that of establishing or maintaining contact between individuals, including mothers and calves. as such, they constitute an important step to understanding the potential effects of communication masking on mother–calf acoustic contact in this species. given the magnitude of the difference in asls and communication ranges between adults and calves, we conclude that even if true sls differ slightly from the asls we present here, they would be unlikely to affect main findings that vessel noise reduces communication range in belugas, and that these reductions may be particularly impactful for separated mother–calf pairs. given the sustained newborn mortality documented in recent years in sle belugas (mosnier et al. 2015; gosselin et al. 2017), understanding all the factors that may contribute to this mortality and the long-standing lack of recovery of this population is important. masking by anthropogenic noise is not an isolated disturbance but may act synergistically with other factors that can also affect survival and reproduction. acknowledgements the authors thank sépaq and parks canada for endorsing the temporary observation tower in baie sainte-marguerite. the authors also thank dr kenneth shorter (university of michigan) for kindly providing expertise for dtag calibration and settings, michel moisan and timothée perrero for their help with dtag deployments and jaclyn aubin for assistance in the field. the authors are grateful to the anonymous reviewers whose constructive suggestions on earlier drafts of this manuscript contributed significantly to its quality. all research was conducted in accordance with the canadian council on animal care guidelines for the ethical use and care of animals in science and had approval from the animal care and welfare committee relating to the application for use of animals at oceanogràfic (oce-9-16, oce-14-18). the project also had permits for the use of dtags (iml-18-3), from parks canada (sagmp-2016-21958 and sagmp-2018-28758), from the species at risk act (que-mm02-2016 and que-lep-001-2018) and from fisheries and oceans canada (iml-2018-024). references aguilar de soto n., madsen p.t., tyack p., arranz p., marrero j., fais a., revelli e. & johnson m. 2012. no shallow talk: cryptic strategy in the vocal communication of blainville’s beaked whales. marine mammal science 28, e75–e92, doi: 10.1111/j.1748-7692.2011.00495.x. ames a.e. & vergara v. 2020. trajectories of vocal repertoire development in beluga (delphinapterus leucas) calves: insights from studies a decade apart. aquatic mammals 46, 344–366, doi: 10.1578/am.46.4.2020.344. angiel n.m. 1997. the vocal repertoire of the beluga whale in bristol bay, alaska. msc thesis, university of washington. au w.w.l. 1993. the sonar of dolphins. new york, ny: springer. au w.w.l., carder d.a., penner r.h. & scronce b.l. 1985. demonstration of adaptation in beluga whale echolocation signals. the journal of the acoustical society of america 77, 726–730, doi: 10.1121/1.392341. au w.w.l., ford j.k.b., horne j.k. & allman k.a.n. 2004. echolocation signals of free-ranging killer whales (orcinus orca) and modeling of foraging for chinook salmon (oncorhynchus tshawytscha). the journal of the acoustical society of america 115, 901–909, doi: 10.1121/1.1642628. au w.w.l., penner r.h. & kadane j. 1982. acoustic behavior of echolocating atlantic bottlenose dolphins. the journal of the acoustical society of america 71, 1269–1275, doi: 10.1121/1.387733. awbrey f.t., thomas j.a. & kastelein r.a. 1988. low‐frequency underwater hearing sensitivity in belugas, delphinapterus leucas. the journal of the acoustical society of america 84, 2273–2275, doi: 10.1121/1.397022. bain d.e. & dahlheim m.e. 1994. effects of masking noise on detection thresholds of killer whales. in t.d. loughlin (ed.): marine mammals and the exxon valdez. pp. 243–256. san diego, ca: academic press. belikov r.a. & bel’kovich v.m. 2003. underwater vocalization of the beluga whales (delphinapterus leucas) in a reproductive gathering in various behavioral situations. oceanology 43, 112–120. belikov r.a. & bel’kovich v.m. 2006. high-pitched tonal signals of beluga whales (delphinapterus leucas) in a summer assemblage off solovetskii island in the white sea. acoustical physics 52, 125–131, doi: 10.1134/s1063771006020023. belikov r.a. & bel’kovich v.m. 2008. communicative pulsed signals of beluga whales in the reproductive gathering off solovetskii island in the white sea. acoustical physics 54, 115–123, doi: 10.1134/s1063771008010168. bojanowski e., veit f. & todt d. 2000. the development of a bivocal signature whistle in a bottlenose dolphin calf. european research on cetaceans 14, 70–74. bowles a.e., grebner d.m., musser w.b., nash j.s. & crance j.l. 2015. disproportionate emission of bubble streams with killer whale biphonic calls: perspectives on production and function. the journal of the acoustical society of america 137, el165–el170, doi: 10.1121/1.4905882. boyd i., frisk g., urban e., tyack p., ausubel j., seeyave s., cato d., southall b., weise m., adrew r., akamatsu t., dekeling r., erbe c., farmer d., gentry r., gross t., hawkins a., li f., metcalf k., miller j.h., moretti d., rodrigo c. & shinke t. 2011. an international quiet ocean experiment. oceanography 24, 174–181, doi: 10.5670/oceanog.2011.37. branstetter b.k., moore p.w., finneran j.j., tormey m.n. & aihara h. 2012. directional properties of bottlenose dolphin (tursiops truncatus) clicks, burst-pulse, and whistle sounds. the journal of the acoustical society of america 131, 1613–1621, doi: 10.1121/1.3676694. brenowitz e. 1982. long-range communication of species identity by song in the red-winged blackbird. behavioral ecology and sociobiology 10, 29–38, doi: 10.1007/bf00296393. brown gladden j.g., ferguson m.m., friesen m.k. & clayton j.w. 1999. population structure of north american beluga whales (delphinapterus leucas) based on nuclear dna microsatellite variation and contrasted with the population structure revealed by mitochondrial dna variation. molecular ecology 8, 347–363, doi: 10.1046/j.1365-294x.1998.00559.x. brumm h. & slabbekoorn h. 2005. acoustic communication in noise. advances in the study of behavior 35, 151–209, doi: 10.1016/s0065-3454(05)35004-2. buckstaff k.c. 2004. effects of watercraft noise on the acoustic behavior of bottlenose dolphins. tursiops truncatus, in sarasota bay, florida. marine mammal science 20, 709–725, doi: 10.1111/j.1748-7692.2004.tb01189.x. caldwell m.c. & caldwell d.k. 1965. individualized whistle contours in bottle-nosed dolphins (tursiops truncatus). nature 207, 434–435, doi: 10.1038/207434a0. casey c., sills j. & reichmuth c. 2016. source level measurements for harbor seals and implications for estimating communication space. proceedings of meetings on acoustics 27, article no. 010034, doi: 10.1121/2.0000353. castellote m., mooney t.a., quakenbush l., hobbs r., goertz c. & gaglione e. 2014. baseline hearing abilities and variability in wild beluga whales (delphinapterus leucas). journal of experimental biology 217, 1682–1691, doi:10.1242/jeb.093252 clark c.w., ellison w.t., southall b.l., hatch l., van parijs s.m., frankel a. & ponirakis d. 2009. acoustic masking in marine ecosystems: intuitions, analysis, and implication. marine ecology progress series 395, 201–222, doi: 10.3354/meps08402. cranford t.w., amundin m. & norris k. s. 1996. functional morphology and homology in the odontocete nasal complex: implications for sound generation. journal of morphology 228, 223–285, doi: 10.1002/(sici)1097-4687(199606)228:3<223::aid-jmor1>3.0.co;2-3. cranford t.w., elsberry w.r., blackwood d.j., carr j.a., kamolnick t., todd m., van bonn w.g., carder d.a., ridgway s.h., bozlinski d.m. & decker e.c. 2000. two independent sonar signal generators in the bottlenose dolphin: physiologic evidence and implications. the journal of the acoustical society of america 108, 2613–2614, doi: 10.1121/1.4743727. cosewic 2014. cosewic assessment and status report on the beluga whale, delphinapterus leucas, st. lawrence estuary population, in canada. ottawa: committee on the status of endangered wildlife in canada. dfo 2014. status of beluga (delphinapterus leucas) in the st. lawrence river estuary. dfo canadian science advisory secretariat science advisory report 2013/076. ottawa: fisheries and oceans canada. dfo 2017. review of the effectiveness of recovery measures for st. lawrence estuary beluga. ottawa: fisheries and oceans canada. dfo 2018. potential effects of the construction of marine terminals in the saguenay fjord on the st. lawerence beluga whale and its habitat. dfo canadian science advisory secretariat science response 2018/025. ottawa: fisheries and oceans canada. dfo 2020. action plan to reduce the impact of noise on the beluga whale and other marine mammals at risk in the st. lawrence estuary. ottawa: fisheries and oceans canada. duarte de figueiredo l. & simão s.m. 2009. possible occurrence of signature whistles in a population of sotalia guianensis (cetacea, delphinidae) living in sepetiba bay, brazil. the journal of the acoustical society of america 126, 1563–1569, doi: 10.1121/1.3158822. erbe c. 2000. detection of whale call in noise: performance comparison between a beluga whale, human listeners, and a neural network. the journal of the acoustical society of america 108, 297–303, doi: 10.1121/1.429465. erbe c. 2012. effects of underwater noise on marine mammals. in a.n. popper & a.d. hawkins (eds.): effects of noise on aquatic life. pp. 17–22, new york: springer. erbe c. & farmer d.m. 1998. masked hearing thresholds of a beluga whale (delphinapterus leucas) in icebreaker noise. deep sea research part ii 45, 1373–1388, doi: 10.1016/s0967-0645(98)00027-7. erbe c., reichmuth c., cunningham k., lucke k. & dooling r. 2016. communication masking in marine mammals: a review and research strategy. marine pollution bulletin 103, 15–38, doi: 10.1016/j.marpolbul.2015.12.007. faucher a. 1988. the vocal repertoire of the st. lawrence estuary population of beluga whale (delphinapterus leucas) and its behavioural, social and environmental contexts. msc thesis, dalhousie university, halifax. finneran j.j., carder d.a., dear r., belting t., mcbain j., dalton l. & ridgway s.h. 2005. pure tone audiograms and possible aminoglycoside-induced hearing loss in belugas (delphinapterus leucas). the journal of the acoustical society of america 117, 3936–3943, doi: 10.1121/1.1893354. finneran j.j., schlundt c.e., dear r., carder d.a. & ridgway s.h. 2002. temporary shift in masked hearing thresholds in odontocetes after exposure to single underwater impulses from a seismic watergun. the journal of the acoustical society of america 111, 2929–2940, doi: 10.1121/1.1479150. fish m. & mowbray w. 1962. production of underwater sounds by the white whale or beluga, delphinapterus leucas. journal of marine research 20, 149–162. frankel a.s., zeddies d., simard p. & mann d. 2014. whistle source levels of free-ranging bottlenose dolphins and atlantic spotted dolphins in the gulf of mexico. the journal of the acoustical society of america 135, 1624–1631, doi: 10.1121/1.4863304. fripp d. & tyack p. 2008. postpartum whistle production in bottlenose dolphins. marine mammal science 24, 479–502, doi: 10.1111/j.1748-7692.2008.00195.x. frost k.j., russel r.b. & lowry l.b. 1992. killer whales, orcinus orca, in the southeastern bering sea: recent sightings and predation on other marine mammals. marine mammal science 8, 110–119, doi: 10.1111/j.1748-7692.1992.tb00370.x. gervaise c., simard y., roy n., kinda b. & ménard n. 2012. shipping noise in whale habitat: characteristics, sources, budget, and impact on belugas in saguenay–st lawrence marine park hub. the journal of the acoustical society of america 132, 76–89, doi:10.1121/1.4728190 gosselin j.-f., hammill m.o., mosnier a. & lesage v. 2017. abundance index of st. lawrence estuary beluga, delphinapterus leucas, from aerial visual surveys flown in august 2014 and an update on reported deaths. dfo canadian science advisory secretariat research document 2017/019. ottawa: fisheries and oceans canada. halliday w.d., scharffenberg k., macphee s., hilliard r.c., mouy x., whalen d., loseto l.i., & insley s.j. 2019. beluga vocalizations decrease in response to vessel traffic in the mackenzie river estuary. arctic 72, 337–346, doi: 10.14430/arctic69294. hill h.m. 2009. the behavioral development of two beluga calves during the first year of life. international journal of comparative psychology 22, 234–253. hill h.m., guarino s., calvillo a., gonzalez a., zuniga k., bellows c., polasek l. & sims c. 2017. lateralized swim positions are conserved across environments for beluga (delphinapterus leucas) mother–calf pairs. behavioural processes 138, 22–28, doi: 10.1016/j.beproc.2017.01.018. holt m.m., noren d.p. & emmons c.k. 2011. effects of noise levels and call types on the source levels of killer whale calls. the journal of the acoustical society of america 130, 3100–3106, doi: 10.1121/1.3641446. janik v.m. 2000. source levels and the estimated active space of bottlenose dolphin (tursiops truncatus) whistles in the moray firth, scotland. journal of comparative physiology a 186, 673–680, doi: 10.1007/s003590000120. janik v.m. & sayigh l.s. 2013. communication in bottlenose dolphins: 50 years of signature whistle research. journal of comparative physiology a 199, 479–489, doi:10.1007/s00359-013-0817-7. jensen f.h., beedholm k., wahlberg m., bejder l. & madsen p.t. 2012. estimated communication range and energetic cost of bottlenose dolphin whistles in a tropical habitat. the journal of the acoustical society of america 131, 582–592, doi: 10.1121/1.3662067. jensen f.h, bejder l., wahlberg m., aguilar de soto n., johnson m. & madsen p. 2009. vessel noise effects on delphinid communication. marine ecology progress series 395, 161–175, doi: 10.3354/meps08204. jensen f.h., bejder l., wahlberg m. & madsen p.t. 2009. biosonar adjustments to target range of echolocating bottlenose dolphins (tursiops sp) in the wild. journal of experimental biology 212, 1078–1086, doi: 10.1242/jeb.025619. jensen f.h., keller o.a., tyack p.l. & visser f. 2020. dynamic biosonar adjustment strategies in deep-diving risso’s dolphins driven partly by prey evasion. journal of experimental biology 223, jeb.216283, doi: 10.1242/jeb.216283. johnson c.s., mcmanus m.w. & skaar d. 1989. masked tonal hearing thresholds in the beluga whale. the journal of the acoustical society of america 85, 2651–2654, doi: 10.1121/1.397759. johnson m., madsen p.t., zimmer w.m.x., aguilar de soto n. & tyack p.l. 2006. foraging blainville’s beaked whales (mesoplodon densirostris) produce distinct click types matched to different phases of echolocation. journal of experimental biology 209, 5038–5050, doi: 10.1242/jeb.02596. johnson m.p. & tyack p.l. 2003. a digital acoustic recording tag for measuring the response of wild marine mammals to sound. ieee journal of oceanic engineering 28, 3–12, doi: 10.1109/joe.2002.808212. karenina k., giljov a., baranov v., osipova l., krasnova v. & malashichev y. 2010. visual laterality of calf–mother interactions in wild whales. plos one 5, 5–11, doi: 10.1371/journal.pone.0013787. karlsen j.d., bisther a., lydersen c., haug t. & kovacs k.m. 2002. summer vocalisations of adult male white whales (delphinapterus leucas) in svalbard, norway. polar biology 25, 808–817, doi: 10.1007/s00300-002-0415-6. kasuya t. 1995. overview of cetacean life histories: an essay in their evolution. developments in marine biology 4, 481–497, doi: 10.1016/s0163-6995(06)80048-x. killebrew d.a., mercado e. iii, herman l.h. & pack a.a. 2001. sound production of a neonate bottlenose dolphin. aquatic mammals 27, 34–44. king s.l., guarino e., keaton l., erb l. & jaakkola k. 2016. maternal signature whistle use aids mother–calf reunions in a bottlenose dolphin tursiops truncatus. behavioural processes 126, 64–70, doi: 10.1016/j.beproc.2016.03.005. klishin v.o., popov v.v & supin a.y. 2000. hearing capabilities of a beluga whale, delphinapterus leucas. aquatic mammals 26, 212–228. krasnova v.v., bel’kovich v.m. & chernetsky [chernetskii] a.d. 2006. mother–infant spatial relations in wild beluga (delphinapterus leucas) during postnatal development under natural conditions. biology bulletin 33, 53–58, doi: 10.1134/s1062359006010079. krasnova v.v., bel’kovich v.m. & chernetskii [chernetsky] a.d. 2009. formation of behavior in the white sea beluga calf, delphinapterus leucas, during early postnatal ontogenesis. russian journal of marine biology 35, 53–59, doi: 10.1134/s1063074009010088. laerd statistics 2016. test of two proportions using spss statistics. statistical tutorials and sofware guides. accessed on the internet at https://statistics.laerd.com/ on 15 november 2020. lair s., measures l.n. & martineau d. 2016. pathologic findings and trends in mortality in the beluga (delphinapterus leucas) population of the st lawrence estuary, quebec, canada, from 1983 to 2012. veterinary pathology 53, 22–36, doi: 10.1177/0300985815604726. lammers m.o., au w.w.l. & herzing d.l. 2003. the broadband social acoustic signaling behavior of spinner and spotted dolphins. the journal of the acoustical society of america 114, 1629–1639, doi: 10.1121/1.1596173. le bot o., simard y., roy n. & edric gervaise c. 2016. whistle source levels of free-ranging beluga whales in saguenay–st. lawrence marine park. the journal of the acoustical society of america 140, el89–el93, doi: 10.1121/1.4955115. lefebvre s.l., michaud r., lesage v. & berteaux d. 2012. identifying high residency areas of the threatened st lawrence beluga whale from fine-scale movements of individuals and coarse-scale movements of herds. marine ecology progress series 450, 243–257, doi: 10.3354/meps09570. lent p.c. 1966. calving and related social behavior in the barren-ground caribou. zeitschrift fuer tierpsychologie 23, 701–756, doi: 10.1111/j.1439-0310.1966.tb01707.x. lesage v., barrette c., kingsley m.c.s. & sjare b. 1999. the effects of vessel noise on the vocal behaviour of belugas in the st lawrence estuary, canada. marine mammal science 15, 65–84, doi: 10.1111/j.1748-7692.1999.tb00782.x. lesage v., mcquinn i.h., carrier d., gosselin j.f. & mosnier a. 2014. exposure of the beluga (delphinapterus leucas) to marine traffic under various scenarios of transit route diversion in the st. lawrence estuary. dfo canadian science advisory secretariat research document 2013/125. ottawa: fisheries and oceans canada. lesage v., measures l., mosnier a., lair s., michaud r. & béland p. 2014. mortality patterns in st. lawrence estuary beluga (delphinapterus leucas), inferred from the carcass recovery data, 1983-2012. dfo canadian science advisory secretariat research document 2013/118. ottawa: fisheries and oceans canada. lima a. & le pendu y. 2014. evidence for signature whistles in guiana dolphins (sotalia guianensis) in ilhéus, northeastern brazil. the journal of the acoustical society of america 136, 3178–3185, doi: 10.1121/1.4900829. lohr b., wright t.f. & dooling r.j. 2003. detection and discrimination of natural calls in masking noise by birds: estimating the active space of a signal. animal behaviour 65, 763–777, doi:10.1006/anbe.2003.2093 madsen p.t., lammers m., wisniewska d. & beedholm k. 2013. nasal sound production in echolocating delphinids (tursiops truncatus and pseudorca crassidens) is dynamic, but unilateral: clicking on the right side and whistling on the left side. journal of experimental biology 216, 4091–4102, doi: 10.1242/jeb.091306. madsen p.t., johnson m., aguilar de soto n., zimmer w.m.x. & tyack p. 2005. biosonar performance of foraging beaked whales (mesoplodon densirostris). journal of experimental biology 208, 181–194, doi: 10.1242/jeb.01327. mann j. & smuts b.b. 1998. natal attraction: allomaternal care and mother–infant separations in wild bottlenose dolphins. animal behaviour 55, 1097–1113, doi: 10.1006/anbe.1997.0637. mann j. & smuts b.b. 1999. behavioral development of wild bottlenose dolphin newborns (tursiops sp). behavioral ecology and sociobiology 136, 529–566, doi: 10.1163/156853999501469. marten k. & marler p. 1977. sound transmission and its significance for animal vocalization. behavioral ecology and sociobiology 2, 271–290, doi: 10.1007/bf00299740. martin p. & bateson p. 2007. measuring behaviour. cambridge: cambridge university press. mccowann b. & reiss d. 1995. whistle contour development in captive-born infant bottle-nosed dolphins (tursiops-truncatus)—role of learning. journal of comparative psychology 109, 242–260, doi: 10.1037/0735-7036.109.3.242. mcquinn i.h., lesage v., carrier d., larrivée g., samson y., chartrand s., michaud r. & theriault j. 2011. a threatened beluga (delphinapterus leucas) population in the traffic lane: vessel-generated noise characteristics of the saguenay–st. lawrence marine park, canada. the journal of the acoustical society of america 130, 3661–3673, doi: 10.1121/1.3658449. mello i. & amundin m. 2005. whistle production preand post-partum in bottlenose dolphins (tursiops truncatus) in human care. aquatic mammals 31, 169–175, doi: 10.1578/am.31.2.2005.169. ménard n., michaud r., chion c. & turgeon s. 2014. documentation of maritime traffic and navigational interactions with st lawrence estuary beluga (delphinaterus leucas) in calving areas between 2003 and 2012. dfo canadian science advisory secretariat research document 2014/003. ottawa: fisheries and oceans canada. merchant n.d., fristrup k.m., johnson m.p., tyack p.l., witt m.j., blondel p. & parks s.e. 2015. measuring acoustic habitats. methods in ecology and evolution 6, 257–265, doi: 10.1111/2041-210x.12330. michaud r. 2005. sociality and ecology in odontocetes. in k.e. ruckstuhi & p. neuhaus (eds.): sexual segregation in vertebrates: ecology of the two sexes. pp. 303–326. cambridge: cambridge university press. miller p.j.o. 2006. diversity in sound pressure levels and estimated active space of resident killer whale vocalizations. journal of comparative physiology a 192, 449–459, doi: 10.1007/s00359-005-0085-2. mishima y., morisaka t., itoh m., matsuo i., sakaguchi a. & miyamoto y. 2015. individuality embedded in the isolation calls of captive beluga whales (delphinapterus leucas). zoological letters 1, article no. 27, doi: 10.1186/s40851-015-0028-x. mohl b., wahlberg m., madsen p.t., miller l.a. & surlykke a. 2000. sperm whale clicks: directionality and source level revisited. the journal of the acoustical society of america 107, 638–648, doi: 10.1121/1.428329. mooney t.a., nachtigall p.e., castellote m., taylor k.a., pacini a.f. & esteban j.a. 2008. hearing pathways and directional sensitivity of the beluga whale, delphinapterus leucas. journal of experimental marine biology and ecology 362, 108–116, doi: 10.1016/j.jembe.2008.06.004. morisaka t., shinohara m., nakahara f. & akamatsu t. 2005. effects of ambient noise on the whistles of indo-pacific bottlenose dolphin populations. journal of mammalogy 86, 541–546, doi: 10.1644/1545-1542(2005)86[541:eoanot]2.0.co;2. morisaka t., shinohara m. & taki m. 2005. underwater sounds produced by neonatal bottlenose dolphins (tursiops truncatus): i. acoustic characteristics. aquatic mammals 31, 248–257, doi: 10.1578/am.31.2.2005.248. morisaka t., yoshida y., akune y., mishima h. & nishimoto s. 2013. exchange of “signature” calls in captive belugas (delphinapterus leucas). journal of ethology 31, 141–149, doi: 10.1007/s10164-013-0358-0. mosnier a., doniol-valcroze t., gosselin j.f., measures l.n. & hammill m.o. 2015. insights into processes of population decline using an integrated population model: the case of the st lawrence estuary beluga (delphinapterus leucas). ecological modelling 314, 15–31, doi: 10.1016/j.ecolmodel.2015.07.006. nedelec s.l., radford a.n., simpson s.d., nedelec b., lecchini d. & mills s.c. 2014. anthropogenic noise playback impairs embryonic development and increases mortality in a marine invertebrate. scientific reports 4, article no. 5891, doi: 10.1038/srep05891. nielsen m.l.k., bejder l., videsen s.k.a., christiansen f. & madsen p.t. 2019. acoustic crypsis in southern right whale mother–calf pairs: infrequent, low-output calls to avoid predation? journal of experimental biology 222, jeb190728, doi: 10.1242/jeb.190728. noren s.r. & edwards e.f. 2007. physiological and behavioral development in delphinid calves: implications for calf separation and mortality due to tuna purse-seine sets. marine mammal science 23, 15–29, doi: 10.1111/j.1748-7692.2006.00083.x. panova e., agafonov a., belikov r. & melnikova f. 2017. vocalizations of captive beluga whales, delphinapterus leucas: additional evidence for contact signature “mixed” calls in belugas. marine mammal science 33, 889–903, doi: 10.1111/mms.12393. panova e.m., belikov r.a., agafonov a.v. & bel’kovich v.m. 2012. the relationship between the behavioral activity and the underwater vocalization of the beluga whale (delphinapterus leucas). oceanology 52, 79–87, doi: 10.1134/s000143701201016x. parks s.e., cusano d.a., van parijs s.m. & nowacek d.p. 2019. acoustic crypsis in communication by north atantic right whale mother–calf pairs on the calving grounds. biology letters 15, article no. 20190485, doi: 10.1098/rsbl.2019.0485. perez j.m., jensen f.h., rojano-doñate l. & aguilar de soto n. 2017. different modes of acoustic communication in deep-diving short-finned pilot whales (globicephala macrorhynchus). marine mammal science 33, 59–79, doi: 10.1111/mms.12344. popov v. & supin a. 1990. electrophysiological studies of hearing in some cetaceans and a manatee. in j.a. thomas & r.a. kastelein (eds.): sensory abilities of cetaceans: laboratory and field evidence. pp. 405–415. new york: plenum press. popper a.n. & hastings m.c. 2009. the effects of human-generated sound on fish. integrative zoology 4, 43–52, doi: 10.1111/j.1749-4877.2008.00134.x. postma l.d. 2017. genetic diversity, population structure and phylogeography among belugas (delphinapterus leucas) in canadian waters: broad to fine-scale approaches to inform conservation and management strategies. phd thesis, university of manitoba, winnipeg. rasmussen m.h., lammers m., beedholm k. & miller l.a. 2006. source levels and harmonic content of whistles in white-beaked dolphins (lagenorhynchus albirostris). the journal of the acoustical society of america 120, 510–517, doi: 10.1121/1.2202865. reeves r.r. & mitchell e. 1988. distribution and seasonality of killer whales in the eastern canadian arctic. rit fiskideildar 11, 136–160. reichmuth c. 2012. psychophysical studies of auditory masking in marine mammals: key concepts and new directions. advances in experimental medicine and biology 730, 23–27, doi: 10.1007/978-1-4419-7311-5_4. richardson w.j., greene c.r., malme c.i. & thomson d.h. 1995. marine mammals and noise. london: academic press. ridgway s.h., carder d.a., kamolnick t., smith r.r., schlundt c.e. & elsberry w.r. 2001. hearing and whistling in the deep sea: depth influences whistle spectra but does not attenuate hearing by white whales (delphinapterus leucas) (odontoceti, cetacea). journal of experimental biology 204, 3829–3841, doi: 10.1242/jeb.204.22.3829. saddler m.r., bocconcelli a., hickmott l.s., chiang g., landea-briones r., bahamonde p.a., howes g., segre p.s. & sayigh l.s. 2017. characterizing chilean blue whale vocalizations with dtags: a test of using tag accelerometers for caller identification. journal of experimental biology 220, 4119–4129, doi: 10.1242/jeb.151498. scheifele p.m., andrew s., cooper r.a., darre m., musiek f.e. & max l. 2005. indication of a lombard vocal response in the st lawrence river beluga. the journal of the acoustical society of america 117, 1486–1492, doi: 10.1121/1.1835508. shapiro a.d. 2006. preliminary evidence for signature vocalizations among free-ranging narwhals (monodon monoceros). the journal of the acoustical society of america 120, 1695–1705, doi:10.1121/1.2226586 shelden k., rugh d., mahoney b. & dahlheim m. 2003. killer whale predation on belugas in cook inlet, alaska: implications for a depleted population. marine mammal science 19, 529–544, doi: 10.1111/j.1748-7692.2003.tb01319.x. simard y., lepage r. & gervaise c. 2010. anthropogenic sound exposure of marine mammals from seaways: estimates for lower st lawrence seaway, eastern canada. applied acoustics 71, 1093–1098, doi: 10.1016/j.apacoust.2010.05.012. sjare b.l. & smith t.g. 1986a. the vocal repertoire of white whales, delphinapterus leucas, summering in cunningham inlet, northwest territories. canadian journal of zoology 64, 407–415, doi: 10.1139/z86-063. sjare b.l. & smith t.g. 1986b. the relationship between behavioral activity and underwater vocalizations of the white whale, delphinapterus leucas. canadian journal of zoology 64, 2824–2831, doi: 10.1139/z86-406. smolker r.a., mann j. & smuts b.b. 1993. use of signature whistles during separations and reunions by wild bottlenose dolphin mothers and infants. behavioral ecology and sociobiology 33, 393–402, doi: 10.2307/4600898. southall b.l., bowles a.e., ellison w.t., finneran j.j., gentry r.l., greene c.r. jr., kastak d., ketten d.r., miller j.h., nachtigall p.e., richardson j.w., thomas j.a. & tyack p.l. 2007. marine mammal noise exposure criteria: initial scientific recommendations. aquatic mammals 33, 273–275, doi: 10.1578/am.33.4.2007.411. southall b.l., finneran j.j., reichmuth c., nachtigall p.e., ketten d.r., bowles a.e., ellison w.t., nowacek d.p. & tyack p.l. 2019. marine mammal noise exposure criteria: updated scientific recommendations for residual hearing effects. aquatic mammals 45, 125–232, doi: 10.1578/am.45.2.2019.125. szabo a. & duffus d. 2008. mother–offspring association in the humpback whale, megaptera novaeangliae: following behaviour in an aquatic mammal. animal behaviour 75, 1085–1092, doi: 10.1016/j.anbehav.2007.08.019. taber s. & thomas p. 1982. calf development and mother–calf spatial relationships in southern right whales. animal behaviour 30, 1072–1083, doi: 10.1016/s0003-3472(82)80197. tennessen j.b. & parks s.e. 2016. acoustic propagation modeling indicates vocal compensation in noise improves communication range for north atlantic right whales. endangered species research 30, 225–237, doi: 10.3354/esr00738. tervo o.m., christoffersen m.f., simon m., miller l.a., jensen f.h., parks s.e. & madsen p.t. 2012. high source levels and small active space of high-pitched song in bowhead whales (balaena mysticetus). plos one 7, e52072, doi: 10.1371/journal.pone.0052072. tyack p.l. & janik v.m. 2013. effects of noise on acoustic signal production in marine mammals. in h. brumm (ed.): animal communication and noise. vol. 2. pp. 251–271. berlin: springer. van parijs s.m. & corkeron p.j. 2001. vocalizations and behaviour of pacific humpback dolphins sousa chinensis. ethology 107, 701–716, doi: 10.1046/j.1439-0310.2001.00714.x. vergara v. 2011. acoustic communication and vocal learning in belugas (delphinapterus leucas). phd thesis, university of british columbia. vergara v. & barrett-lennard l.g. 2008. vocal development in a beluga calf (delphinapterus leucas). aquatic mammals 34, 123–143, doi: 10.1578/am.34.1.2008.123. vergara v., michaud r. & barrett-lennard l.g. 2010. what can captive whales tell us about their wild counterparts? identification, usage, and ontogeny of contact calls in belugas (delphinapterus leucas). international journal of comparative psychology 23, 278–309. vergara v. & mikus m.-a. 2019. contact call diversity in natural beluga entrapments in an arctic estuary: preliminary evidence of vocal signatures in wild belugas. marine mammal science 35, 434–465, doi: 10.1111/mms.12538. videsen s.k.a., bejder l., johnson m. & madsen p.t. 2017. high suckling rates and acoustic crypsis of humpback whale neonates maximise potential for mother–calf energy transfer. functional ecology 31, 1561–1573, doi: 10.1111/1365-2435.12871. wang z.-t., au w.l., rendell l., wang k., wu h.-p., wu y., liu j., duan g. -q., cao h.-j., wang d. 2016. apparent source levels and active communication space of whistles of free-ranging indo-pacific humpback dolphins (sousa chinensis) in the pearl river estuary and beibu gulf, china, peerj 4, e1695, doi: 10.7717/peerj.1695. weihs d. 2004. the hydrodynamics of dolphin drafting. journal of biology 3, article no. 8. wenz g.m. 1962. acoustic ambient noise in the ocean: spectra and sources. the journal of the acoustical society of america 34, 1936–1956, doi: 10.1121/1.1909155. white m.j. jr., norris j., ljungblad d., baron k. & di sciara g. 1978. auditory thresholds of two beluga whales (delphinapterus leucas). technical report 78–109. san diego, ca: hubbs marine research institute. wieland m., jones a. & renn s.c.p. 2009. changing durations of southern resident killer whale (orcinus orca) discrete calls between two periods spanning 28 years. marine mammal science 26, 195–201, doi: 10.1111/j.1748-7692.2009.00351.x. williams r., lacy r.c., ashe e.e., hall a., lehoux c., lesage v., mcquinn i. & pourde s. 2017. predicting responses of st. lawrence beluga to environmental change and anthropogenic threats to orient effective management actions. dfo canadian science advisory secretariat research document 2017/027. ottawa: fisheries and oceans canada. foraging behaviour of sympatrically breeding macaroni (eudyptes chrysolophus) and chinstrap (pygoscelis antarcticus) penguins at bouvetøya, southern ocean research article foraging behaviour of sympatrically breeding macaroni (eudyptes chrysolophus) and chinstrap (pygoscelis antarcticus) penguins at bouvetøya, southern ocean audun narvestad, christian lydersen, kit m. kovacs & andrew d. lowther norwegian polar institute, fram centre, tromsø, norway abstract species with similar ecological requirements that overlap in range tend to segregate their niches to minimize competition for resources. however, the niche segregation possibilities for centrally foraging predators that breed on isolated subantarctic islands may be reduced by spatial constraints and limitations in the availability of alternative prey. in this study we examined spatial and trophic aspects of the foraging niches of two sympatrically breeding penguin species, macaroni (eudyptes chrysolophus; mac) and chinstrap (pygoscelis antarcticus; chin) penguins, at bouvetøya over two breeding seasons. to measure at-sea movements and diving behaviour, 90 macs and 49 chins were equipped with gps loggers and dive recorders during two austral summer breeding seasons (2014/15 and 2017/18). in addition, blood samples from tracked birds were analysed for stable isotopes to obtain dietary information. chins displayed marked interannual variation in foraging behaviour, diving deeper, utilizing a larger foraging area and displaying enriched values of δ15n in 2014/15 compared to the 2017/18 breeding season. in contrast, macs dove to similar depths and showed similar δ15n values, while consistently utilizing larger foraging areas compared to chins. we suggest that low krill abundances in the waters around bouvetøya during the 2014/15 season resulted in chins shifting toward a diet that increased their niche overlap with macs. our findings may partly explain the decreasing number of breeding chins at the world’s most remote island, bouvetøya, while also highlighting the importance of characterizing niche overlap of species using multi-season data sets. keywords ecological niche; niche overlap; central place foraging; competition; stable isotope analysis; biotelemetry abbreviations anova: analysis of variance apf: antarctic polar front chin: chinstrap penguin gis: geospatial information system gps: global positioning system hsd: honestly significant difference test mac: macaroni penguin seac: standard ellipse area corrected for small sample size sia: stable isotope analyses tdr: time–depth recorders ud: utilization distribution   citation: polar research 2022, 41, 6351, http://dx.doi.org/10.33265/polar.v41.6351 copyright: polar research 2022. © 2022 s. skreslet et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. published: 16 march 2022 competing interests and funding: the authors report no conflict of interest. this research was undertaken as part of the norwegian antarctic research expedition programme, financed by the norwegian research council (2014/15) and the norwegian polar institute (2017/18). correspondence to: andrew d. lowther, norwegian polar institute, fram centre, po box 6606 stakkevollan, no-9296, tromsø, norway. e-mail: andrew.lowther@npolar.no   introduction in the southern ocean, all centrally foraging species are air-breathing marine predators (such as otariid seals and seabirds), many of which utilize remote subantarctic islands as terrestrial breeding grounds (barlow et al. 2002; lowther et al. 2014; petry et al. 2018). upwelling of minerals and organic matter caused by internal waves, in addition to influxes of nutrients from land, creates conditions promoting high productivity over the shelf areas of subantarctic islands (park et al. 2008; meyer et al. 2015). offering predictable food availability, these islands support large multispecies marine predator guilds (trivelpiece et al. 1987; adams & brown 1989; reid & croxall 2001; petry et al. 2018). intensified competition for food between various predators, resulting from both high predation pressure and spatiotemporal changes in prey availability, may arise in nearshore waters during the breeding season (dann & norman 2006; elliot et al. 2009). subantarctic islands are distributed close to the apf, which separates warm temperate waters from colder subantarctic and antarctic waters. only south georgia, the south sandwich islands and bouvetøya are south of this key hydrographic feature within the acc. south of the apf, antarctic krill (euphausia superba; hereafter ‘krill’) is the main food resource for most marine predators (croxall et al. 1988; davis & darby 1990; atkinson et al. 2004; atkinson et al. 2006; atkinson et al. 2008; reid & croxall 2001). however, the local abundance of krill can vary enormously, introducing considerable variability to food web structure and concomitantly the foraging ecology of krill predators (croxall & davis 1999; reid & croxall 2001; barbosa et al. 2012; horswill et al. 2017). additionally, some sectors of the southern ocean, including the acc, have experienced rapid warming since the second half of the 20th century (gille 2002; vaughan et al. 2003), causing concern for future krill abundance and possible cascading effects throughout marine food webs (reid & croxall 2001; thorpe et al. 2007; trivelpiece et al. 2011). penguins are the most abundant group of air-breathing marine predators in the southern ocean (davis & darby 1990) and constitute a significant group of krill consumers (de brooke 2004). during breeding, penguins are central place foragers that attend their nest for chick provisioning (barlow & croxall 2002a; ichii et al. 2007; thiebot et al. 2011; clewlow et al. 2019). unlike sympatrically breeding antarctic fur seals, penguins cannot store food for their offspring as energy-rich milk—they must bring prey back promptly to feed their chicks—nor do they have the mobility of their flying seabirds’ counterparts. consequently, penguins are spatially constrained during breeding (barlow et al. 2002; ichii et al. 2007) and likely vulnerable to the effects of trophic competition (waluda et al. 2010; polito et al. 2015; clewlow et al. 2019). the similar-sized mac and chin both occur in great numbers throughout the southern ocean (birdlife international 2019a, b). however, chins are obligate krill feeders, while macs are more opportunistic and switch readily to other prey types when krill abundance is low (lynnes et al. 2002; miller et al. 2010; rombolá et al. 2010; niemandt et al. 2016; whitehead et al. 2017). at bouvetøya the two species breed sympatrically during the austral summer (isaksen et al. 2000; biuw et al. 2010; blanchet et al. 2013). the penguin breeding season at bouvetøya spans from december to early march, and the nesting cycle of macs and chins is relatively synchronous, as it is throughout their range (trivelpiece et al. 1987; haftorn 1986).following egg laying, female macs leave the nest to forage at sea, with the males incubating the eggs alone until hatching. after hatching, male macs brood and guard the chicks while the females undertake short foraging trips for chick provisioning (haftorn 1986; barlow & croxall 2002b; green et al. 2002; blanchet et al. 2013). unlike macs, both male and female chins undertake incubation and chick provisioning, alternately taking long (multi-day) foraging trips during incubation and short foraging trips during the chick brooding and guarding phase (haftorn 1986; jansen et al. 2002; blanchet et al. 2013). after 20 to 30 days of egg hatching, chicks from different nests gather in crèches (haftorn 1986; jansen et al. 2002). finally, 60 to 70 days after egg hatching, the chicks of both species fledge and go to sea (barlow & croxall 2002b). at nyrøysa, a rocky beach located on the west coast of bouvetøya, macs and chins currently show differing population trajectories. during the last three decades the number of macs has remained stable (1100 breeding pairs), while the number of chins has decreased from about 200 to 40 pairs (isaksen et al. 2000; biuw et al. 2010). bouvetøya is located at the distributional limit of chins, possibly leaving the species in suboptimal conditions with less tolerance to changes in the local ecosystem (fig. 1; strycker et al. 2020). the underlying cause of this decline remains uncertain (blanchet et al. 2013; niemandt et al. 2016), with potential prey competition not to be excluded as a driving factor. as a result of increasing ocean temperatures, krill abundance may decline and the frequency of low krill events around bouvetøya may increase in the future (atkinson et al. 2004; atkinson et al. 2006; atkinson et al. 2019; trivelpiece et al. 2011). in such a scenario, generalist predators, capable of rapidly switching to other available prey species, may gain a competitive advantage over krill specialists (forcada & trathan 2009; trivelpiece et al. 2011; blanchet et al. 2013; niemandt et al. 2016). the mixed breeding colony of macs and chins is therefore an interesting system to study the temporal dynamics of niche overlap between a foraging generalist and a foraging specialist in a changing southern ocean. fig. 1 the location of bouvetøya (54°25’s, 3°20’e) and nyrøysa (red square), where all fieldwork took place. the inset shows the global distribution of chin (red dots) and mac (blue dots) breeding colonies (strycker et al. 2020). in the present study, we combine biotelemetry with sia to examine the foraging niche of macs and chins at bouvetøya over two non-consecutive breeding seasons. signatures of δ15n are used as tracers for trophic levels, while those of δ13c typically reflect the carbon source at the base of the food chain (bearhop et al. 2000; cherel & hobson 2007). by combining sia of blood and biotelemetry we can characterize the spatial and trophic dimensions of the two species’ foraging niches on intraand interseasonal time scales. our goal was to determine whether the overlap in foraging niches between the two species remains consistent across years in terms of habitat use and trophic ecology. material and methods field site our study was conducted at nyrøysa, bouvetøya (54°25’s, 3°20’e; fig. 1), during the austral summer breeding season (mid-december to early february) in 2014/15 and in 2017/18 (hereafter ‘2015’ and ‘2018’). all fieldwork was undertaken as part of the norwegian antarctic research expedition programme, and animal experimentation was conducted under permits from the norwegian food safety authority (permit numbers 2014/230385 and 17/105553). movement and diving behaviour a total of 139 breeding penguins (90 female macs and 49 chins of unknown sex) were instrumented during the two seasons (table 1). only female macs were tagged as the male stays at the nest during most of the breeding season (barlow & croxall 2002b). a pathtrack gps-logger (nano-fix® model 64 × 20 × 17 mm, 22 g) and a cefas technology tdr (g5 data storage tag model 31 × 8 mm, 2.7 g) were attached to the dorsal feathers using tesa© 4651 waterproof tape and loctite® 323 rapid-setting glue (wilson & wilson 1989; wilson et al. 1997). gpss were programmed to record a location every four minutes and the tdrs recorded depth every 2 s. the two instruments were deployed for 5–10 days on each individual, corresponding to 1–13 foraging trips (covering late incubation through to early crèche), after which the animal was recaptured and the instrument package removed. upon retrieval, a blood sample was taken from the brachial vein using a 0.6 × 25 mm needle (fine-ject®; henke sass wolf) and a 2-ml syringe (bd emeraldtm). animal handling, during deployment or recovery, took less than 10 minutes, after which all individuals returned immediately to their nests. table 1 breeding macs and chins deployed with gpss and tdrs for which data amenable for further analysis were collected over two austral summer breeding seasons (2015 and 2018) at bouvetøya. species (year) gpsa tdra blooda chin (2015) 16 (19) 14 (19) 19 (19) chin (2018) 23 (30) 19 (30) 25 (30) mac (2015) 24 (50) 21 (50) 50 (50) mac (2018) 27 (40) 19 (40) 33 (40) a numbers in parentheses represent the total number of samples collected, including those for which either insufficient data or blood samples were available or the electronic instruments failed during deployment. stable isotope sample preparation in 2018, samples were centrifuged for five minutes at 3000 rpm (hettich® eba 20 centrifuge) and plasma was separated from the cell pack using a 100–1000-μl pipette (biopette atm, labnet international inc.) and a 1–200-μl pipette tip (vwrtm). whole blood from 2015 and red blood cells from 2018 were stored in 98% ethanol in heparinized blood containers (bd vacutainer®; becton dickinson). all samples were kept at −18°c until further analysis. statistical analysis of movement and diving behaviour all data from both breeding seasons were processed and analysed using r statistical software version 3.5.2 (r development core team 2018). all geospatial data and biogeochemical data were defined as representing either early (incubation—early brood) or late (late brood—crèche) breeding by the date of instrumentation and the observed breeding state of the adults immediately prior to instrumentation. both gps and tdr data were downloaded using proprietary software (sirtrack & pathtrack archival gps v.1.20 and pathtrack ltd tdr host v.7.6.2, respectively). dive events were defined using a zero-offset correction of 5 m (clewlow et al. 2019) and dive statistics were extracted using the package divemove (luque & fried 2011). raw gps data were treated with a speed filter (mcconnell et al. 1992) set to 20 ms–1 to remove extreme outliers and then locations closer than 200 m to land (representing the accuracy of the gps) were removed manually, resulting in discrete at-sea foraging trips for each individual. interspecific differences in trip duration were subsequently tested for using non-parametric wilcoxon signed-rank tests. a continuous-time model of each foraging trip was created using the package crawl (johnson et al. 2008), which was then used to estimate a location for each dive via temporal interpolation. further, spatially resolved dive data were clustered into two categories, namely, foraging dives and transit dives, using the package mclust (scrucca et al. 2016). here foraging dives are defined as being deeper, and of longer durations, compared to transit dives. penguins are known to undertake deeper and longer dives when searching for, and approaching, prey in foraging locations, while short and shallow dives resemble travelling between discrete foraging areas and the nest site (williams et al. 1992; hart et al. 2010). differences between foraging and transit dives were tested for using wilcoxon signed-rank tests. next, foraging dives partitioned by species, breeding season and early/late breeding stages were subsequently tested for differences in mean maximum dive depth (m) and mean dive duration (s) using two-way anovas and tukey’s hsd tests. statistical analysis of habitat utilization distributions using the estimated locations of foraging dives, 95% kernel uds were created for groups of macs and chins separated by breeding season and early/late breeding stages using the package adehabitathr (calenge 2015), with a smoothing parameter for bivariate normal distribution. in addition, the size and overlap of uds were calculated. polygons of estimated foraging areas were visualized using a gis software, qgis version 3.6.3 (qgis development team 2019). foraging dive behaviour and stable isotope data were visualized using ggplot from the package ggplot2. differences in δ15n and δ13c were explored between species and breeding seasons using two-way anovas and tukey’s hsd tests. seacs were calculated for stable isotope data using the package siber (jackson et al. 2011). values are presented as mean (±standard deviation) and differences were considered to be significant at p < 0.05. sia isotope analyses of δ15n (15n/14c) and δ13c (13c/12c) were carried out for samples of whole blood in 2015 and for red blood cells in 2018 (table 1). isotope ratios in whole blood closely resemble ratios in red blood cells (cherel et al. 2005) and henceforth both red blood cells and whole blood are referred to as ‘blood’. in blood, the turnover rate of stable isotopes of nitrogen and carbon is approximately four weeks, with levels of δ15n (15n/14n) and δ13c (13c/12c) increasing between 2–4‰ and 0–1‰ respectively per trophic level in marine ecosystems (post 2002; inger & bearhop 2008). blood samples were dried at 50°c, pulverized and weighed in tin capsules. dried samples were then combusted in an elemental analyzer (thermo scientific flash ht plus) at 1020°c and analysed on an isotope ratio mass spectrometer (thermo scientific mat253). δ15n and δ13c were determined by normalization to international scales for atmospheric nitrogen and vienna peedee belemnite carbonate. ratios of stable isotopes were calculated using the following equation: and expressed as per mil units (‰) (polito et al. 2015; ratcliffe et al. 2018). all sias were conducted at the stable isotope laboratory at cage—centre for arctic gas hydrate, environment and climate, at uit the arctic university of norway, tromsø. differences in δ15n and δ13c were then explored between species and breeding seasons using two-way anovas and tukey’s hsd tests. seacs were calculated for stable isotope data using the package siber (jackson et al. 2011). results movement and diving behaviour in 2015, macs and chins were instrumented for a mean period of 7.9 (± 2.0) and 6.2 (± 4.6) days, respectively. in 2018 the mean instrumentation periods were 8.9 (± 4.8) days for macs and 6.0 (± 3.5) days for chins. this led to individual macs and chins conducting a mean 3.1 and 2.7 foraging trips in 2015, and 3.3 (± 1.7) and 2.6 (± 2.1) in 2018, respectively. mean trip durations for macs were 3.1 (± 3.7) days in 2015 and 5.4 (± 5.5) days in 2018, while the mean trip durations for chins were 1.4 (± 1.4) and 1.1 (± 0.8) days, respectively, during the same period. the mean foraging range decreased for both species as the breeding season progressed, and it was significantly shorter for chins than for macs throughout the study (early breeding in 2015 and 2018: mac, 149.9 km/158.1 km; chin, 52.2 km/51.5 km; late breeding in 2015 and 2018: mac, 54.1 km/64.3 km; chin, 22.7 km/8.8 km) (wilcoxon rank sum, p < 0.05 in all cases; table 2). chins travelled about three times further offshore during the late breeding season in 2015 compared to the late breeding period in 2018 (wilcoxon rank sum, p < 0.001). table 2 mean (with associated standard deviation), minimum and maximum foraging range (km), for macs and chins in early (incubation and early brood) and late (late brood and crèche) breeding at bouvetøya during the austral summers of 2015 and 2018. species/year early breeding late breeding mean range (km) min. range (km) max. range (km) mean range (km) min. range (km) max. range (km) chin 2015 52.2 ± 46.2 8.2 144.6 22.7 ± 16.0 4.8 59.1 chin 2018 51.5 ± 40.6 2.2 121.1 8.8 ± 6.1 2.1 37.6 mac 2015 149.9 ± 1424 23.1 348.5 64.3 ± 41.0 6.2 178.2 mac 2018 158.1 ± 157.3 3.3 399.0 54.1 ± 57.2 7.2 335.5 foraging dives were significantly deeper, and of longer duration, compared to transit dives for both macs and chins throughout the breeding seasons of 2015 and 2018 (wilcoxon rank sum, p < 0.001). during foraging, chins exhibited maximum dive depths and durations that were generally similar to macs in 2015, with the deepest and longest dive being 120 m and 160 s for chins, and 116 m and 186 s for macs. a clearer difference in the two dive parameters between the two species was detected in 2018, with the deepest and longest dive being 85 m and 160 s for chins, and 123 m and 170 s for macs. intraspecific differences in foraging dive behaviour between breeding seasons were detected for both species. this difference was most pronounced for chins, which dove significantly deeper (mean difference 12.4 and 31.2 m, respectively) and longer (mean difference 31.4 and 69.1 s, respectively) during foraging in early and late breeding seasons in 2015 compared to the same stages of breeding in 2018 (tukey’s hsd, p < 0.001; fig. 2; table 3). for macs the interannual differences in foraging dive behaviour were less pronounced, with individuals diving deeper (mean difference 6.8 and 4.9 m) during both the early and late breeding stages in 2018 compared to the same stages of breeding in 2015 (tukey’s hsd, p < 0.001; fig. 2; table 3). no specific pattern was observed in mean maximum dive duration for macs between breeding seasons; however, the species dove longer in latecompared to early breeding (mean difference 8.3 and 2.3 s, respectively) in both 2015 and 2018 (tukey’s hsd, p < 0.01; fig. 2; table 3). interestingly, chins dove significantly deeper and longer in the late breeding stage in 2015, yet not in 2018, compared to the macs throughout both breeding seasons (tukey’s hsd, p < 0.001; fig. 2; table 3). fig. 2 comparisons of estimated 95% kernel uds for macs (grey) and chins (orange) in early (incubation and early brood) and late (late brood and crèche) breeding at bouvetøya, with the apf visible to the north of bouvetøya. (a) early breeding, 2015. (b) late breeding, 2015. (c) early breeding, 2018. (d) late breeding, 2018. the greatest interspecific difference in uds was observed between macs and chins throughout the breeding season of 2018, while the greatest intraspecific difference in uds was observed for chins between early and late breeding the same year. compared to the early breeding periods in 2015 and 2018, both macs and chins were foraging closer to the nest site during the late breeding periods in 2015 and 2018. compared to 2015, both species displayed larger uds in the early breeding period in 2018 and smaller uds in the late breeding period in 2018. table 3 mean maximum dive depth (m) and mean dive duration (s) of foraging dives, with associated standard deviation, undertaken by macs and chins in early (incubation and early brood) and late (late brood and crèche) breeding at bouvetøya during the austral summers of 2015 and 2018. species/year early breeding late breeding n (trips) n (dives) max. depth (m) dive duration (s) n (trips) n (dives) max. depth (m) dive duration (s) chin 2015 10 3035 36.6 ± 17.3 101 ± 25.5 33 4048 58.4 ± 24.8 125 ± 32.5 chin 2018 16 3597 24.2 ± 11.6 69.6 ± 23.0 45 2980 27.2 ± 14.9 65.9 ± 21.9 mac 2015 15 3076 30.8 ± 18.3 90.2 ± 29.1 62 12 641 38.5 ± 21.3 98.5 ± 31.7 mac 2018 24 5553 37.6 ± 16.7 95.1 ± 24.6 48 4368 43.4 ± 23.7 97.4 ± 29.3 habitat uds there was a marked difference between the two species in the size of the area used for foraging, with macs typically exploiting an area more than six times larger than chins (fig. 3). across both breeding seasons, the 95% ud of both macs and chins decreased as the breeding season progressed, though the difference between early and late breeding season was less pronounced in 2015 (early breeding in 2015 and 2018: mac, 140 653.5 km2/382 128.9 km2; chin, 22 640.0 km2/43 985.0 km2; late breeding in 2015 and 2018: mac, 54 252.0 km2/20 840.4 km2; chin, 4362.9 km2/1584.5 km2; fig.3). most notably, chins utilized an almost three times larger foraging area during late breeding in 2015 compared to the same part of the breeding season in 2018 (fig. 3). there was also considerable overlap in the 95% ud of the two species, with macs occupying between 88 and 100% of the habitat exploited by chins in both breeding seasons (fig. 3). fig. 3 mean (a) maximum dive depth (m) and (b) dive duration (s), with associated standard deviation bars, for macs and chins in early (incubation and early brood) and late (late brood and crèche) breeding at bouvetøya during the austral summers of 2015 and 2018. the chins showed the greatest variation in dive behaviour (mean maximum depth and mean dive duration) between the two breeding seasons, while the macs showed little variation in dive behaviour between 2015 and 2018. sias nitrogen ratios of chins in 2015 were significantly higher compared to their conspecifics in 2018 (δ15n in 2015 and 2018, 11.1 ± 0.3‰/9.4 ± 0.6‰) and to macs from both breeding seasons (δ15n in 2015 and 2018, 10.7 ± 0.2‰/10.4 ± 0.3‰; tukey’s hsd, p < 0.001 in all cases; fig. 4, table 4). importantly, chins in 2018 had the lowest values of δ15n of all groups across breeding seasons (tukey’s hsd, p < 0.001 in all cases; fig. 4, table 4). similarly, macs δ15n were elevated in 2015 compared to in 2018 (tukey’s hsd, p < 0.05; fig. 4, table 4); however, considering a 2‰ increase in δ15n per trophic level, the difference is of little ecological importance. δ13c values were significantly lower during 2015 for both species (mac in 2015 and 2018, −22.6 ± 0.3‰/−23.5 ± 0.5‰; chin in 2015 and 2018, −23.6 ± 0.3‰/−25.3 ± 0.3‰; tukey’s hsd, p < 0.001; fig. 4, table 4). fig. 4 interannual variation in δ15n and δ13c values, with 95% confidence intervals drawn for means, in blood of macs and chins breeding at bouvetøya during the austral summers of 2015 and 2018. the chins showed the greatest variation in δ15n and δ13c between the two breeding seasons, suggesting a shift in prey consumed by the species in 2015 and 2018. table 4 mean stable isotope measurements of δ15n and δ13n (‰), with associated standard deviation bars, and seacs for macs and chins breeding at bouvetøya during the austral summers of 2015 and 2018. species/year δ15n (‰) δ13c (‰) seac chin 2015 11.1 ± 0.3 −23.6 ± 0.3 0.27 chin 2018 9.4 ± 0.6 −25.3 ± 0.3 0.46 mac 2015 10.7 ± 0.2 −22.6 ± 0.3 0.24 mac 2018 10.4 ± 0.3 −23.5 ± 0.5 0.39 discussion we demonstrate substantial spatial overlap in the foraging niches of sympatrically breeding macs and chins across two breeding seasons at nyrøysa, bouvetøya. at this location, blanchet et al. (2013) investigated the potential for prey competition between three main krill predators at bouvetøya (i.e., macs, chins and antarctic fur seals) over a single summer breeding season in 2007. these authors concluded that there was potential for competitive overlap among the three species, but that both spatial and temporal partitioning of foraging areas likely reduced direct competition (blanchet et al. 2013). however, given the short duration of their study, temporal variation in niche overlap between the three species was not evaluated (see waluda et al. 2010; horswill et al. 2017 for examples). our study clearly shows temporal variation in the foraging niche of macs and chins within and between breeding seasons at the island, highlighting the importance of including both intraand interseasonal variations when considering the possibility for prey competition. the foraging behaviour of breeding penguins is likely to reflect the increasing energy demands of their chicks as the breeding season progresses. in line with this expectation, we found that macs and chins utilized larger foraging areas during early breeding in 2015 and 2018, when being less constrained by nest duties and free to travel for several days before returning. both species then decreased their foraging range later in the breeding season as a result of having to return more regularly to the breeding site for chick provisioning as the chicks grow older (late brood and crèche) throughout our study. despite this general trend, we found distinct differences in the foraging range of macs and chins between the two breeding seasons, with both species utilizing larger foraging areas and travelling further offshore from bouvetøya during late breeding in 2015 compared to late breeding in 2018. when prey is scarce, penguins are likely to increase their foraging range and utilize a larger section of the water column. such responses to low prey availability have been linked to reduced spatial overlap, and thereby reduced prey competition, between sympatrically breeding penguin species elsewhere (trivelpiece et al. 1987; hindell et al. 1995; mori & boyd 2004). hence, the larger foraging range of macs and chins during the late breeding phase in 2015 may signal low prey densities in nearshore waters of bouvetøya during this period. still, macs occupied nearly the entire horizontal foraging area of the chins throughout our study, highlighting the latter species’ general lack of spatial niche segregation previously described by blanchet et al. (2013). as the breeding season progressed and adult penguins became more constrained in how long (and therefore how far) they could travel due to chick provisioning, both species appeared to increase their foraging efforts by diving deeper. chins in the latter stage of breeding in 2015 dove approximately 19 m deeper than during the breeding season of 2007 (blanchet et al. 2013), and 31 m deeper than their conspecifics at the same stage in 2018. most notably, chins in the late breeding season of 2015 dove deeper than macs in 2007 (blanchet et al. 2013), 2015 or 2018 (current study). this deeper diving effort was generally matched with longer dive durations of chins between 2015 and 2018, though dive durations in 2015 were not notably different from those in 2007 (blanchet et al. 2013). in contrast, mean maximum dive depth of macs showed little variation either during the period of this study or in comparison with 2007 (blanchet et al. 2013), suggesting that macs were consistently targeting prey at similar depths. in comparison, chins were likely searching for prey in deeper water layers in 2015, presumably because less prey were available close to the sea surface. still, the vertical niche of the two species showed significant overlap throughout the breeding season in 2015, which may have resulted in increased competition for less abundant prey between macs and chins breeding on nyrøysa. hence, chins may have faced challenges because of the need for increased foraging efforts in combination with interspecific competition during the 2015 breeding season. the isotopic data support the notion that there was a shift in prey resources around bouvetøya between 2015 and 2018. considering each species separately, the differences in δ13c between 2015 and 2018 could indicate foraging in different habitats. however, a much greater increase in foraging range, with less variability in δ13c, was detected for macs between the two seasons. therefore, a more likely explanation is that macs and chins were feeding on prey with slightly different carbon signals between breeding seasons. this assumption was supported by a clear difference in chins δ15n data between 2015 and 2018. assuming a 2‰ increase in δ15n for each trophic level (hobson & welch 1992), during 2018 macs likely consumed more prey from higher trophic levels compared to chins. conversely, during the breeding season in 2015, chins exhibited the highest δ15n values of any group in the study. the bathymetric features around bouvetøya are thought to support high aggregations of krill (krafft et al. 2010), and earlier dietary studies have found that chins nesting on nyrøysa forage mainly on krill during the breeding season (haftorn 1986; niemandt et al. 2016). in contrast, macs nesting on nyrøysa have been found to forage on a wide selection of prey species, including myctophid fishes (>40% of the diet by mass) as well as krill and the abundant southern ocean krill (thysanoessa macrura; niemandt et al. 2016). under the assumption that 2018 reflected a breeding season in which chins fed on krill and macs were mixed-prey foragers, there are three possible explanations for the significant differences in δ15n observed for chins in 2015. first, fish, being generally situated at a trophic level higher than krill, may serve as an alternative food resource for some species of southern ocean penguins when krill is at low densities (croxall et al. 1988; ichii et al. 2007; miller & trivelpiece 2008; ratcliffe et al. 2018). as a result of the mesopelagic nature of myctophid fish, this alternative food resource is typically found in deeper water layers (lishman & croxall 1983; miller & trivelpiece 2008). hence, the deeper foraging dives of the chins in 2015 could indicate that they were foraging on myctophid fish (hobson & welch 1992; tierney et al. 2008). second, given that δ15n in krill may also vary by as much as 2‰ based on age (polito et al. 2013), variation in the dominant life history stage of krill available around bouvetøya may have driven the isotopic differences in chins between 2015 and 2018. however, earlier dietary analysis of seals and penguins on nyrøysa suggests little interannual variation in the size (a close proxy for age) of krill consumed by predators at bouvetøya (kirkman et al. 2000; niemandt et al. 2016; tarroux et al. 2016). third, fasting or starving penguins are likely to display elevated blood and plasma levels of δ15n (cherel et al. 2005). variation in δ15n seen between study breeding seasons is also consistent with chins experiencing greater catabolism of their own tissues during the breeding season of 2015. the annual density and distribution of krill are known to vary greatly at local scales in the southern ocean (brierley et al. 2002; miller & trivelpiece 2008), but the frequency of low krill abundance events is unknown around bouvetøya. two earlier studies of predator diets did not detect clear evidence for krill scarcity in the area (blanchet et al. 2013; niemandt et al. 2016). conversely, based on isotope data, tarroux et al. (2016) proposed that low krill densities in 2015 likely led to antarctic fur seals breeding on nyrøysa targeting more fish and cephalopods, supporting the underlying mechanism that we suggest drove the behaviour of chins in 2015 in our study. the number of breeding pairs of chins has been decreasing on nyrøysa over recent decades, during which intermittent monitoring has been taking place (isaksen et al. 2000; biuw et al. 2010). competition for breeding space (hofmeyr et al. 2005; niemandt et al. 2016), destruction of nest sites by landslides and the killing of penguins in rockfalls, as well as aggressive encounters by antarctic fur seals (isaksen et al. 2000; niemandt et al. 2016; pers. obs.), have all been proposed as possible explanations for the decreasing number of breeding chins at the nyrøysa study site. however, given that these pressures are likely to impact both species equally, they fail to explain the differing population trajectories observed for macs and chins at nyrøysa (biuw et al. 2010). unlike chins, macs are known to readily prey switch (waluda et al. 2010), in addition to utilizing deeper water layers (blanchet et al. 2013) and larger foraging areas during breeding (thiebot et al. 2011; this study). this makes macs potentially more flexible to changes in prey community composition and prey density while raising offspring. another consideration is that bouvetøya is located at the eastern distributional limit for chins. this could mean that at this site this species is living at the edge of its ecological niche, with little tolerance for fluctuations in krill densities. consequently, when both species are constrained in how far they can travel, and under conditions of low krill availability, the mixed-prey foraging macs are likely to gain a competitive advantage. thus, increased interspecific competition arising from krill scarcity may lead to reduced individual fitness and reproductive performances for chins at bouvetøya. conclusion by describing the spatial and isotopic foraging ecology of macs and chins over two complete breeding seasons, this study demonstrates that single-season studies characterizing levels of niche segregation may not be appropriate as they do not fully incorporate dynamic aspects typical of marine ecosystems. although little is known regarding krill fluctuations/availability at bouvetøya, low krill events may already be common enough to have driven the decline in breeding number of chins on nyrøysa, possibly exacerbated by competition for food from sympatrically breeding macs. the apf is predicted to move southwards as a response to increasing ocean temperatures (gille 2002; cristofari et al. 2018), resulting in a southward contraction of krill distribution towards the continent (atkinson et al. 2019). only a few hundred kilometres south of the apf, bouvetøya is likely to fall outside the distribution range of krill in the future (atkinson et al. 2004; atkinson et al. 2006; trathan et al. 2015), which may drive the breeding population of chins, the easternmost distributed of the species, to local extirpation. references adams n.j. & brown c.r. 1989. dietary differentiation and trophic relationships in the sub-antarctic penguin community at marion island. marine ecology progress series 57, 249–258, doi: 10.3354/meps057249. atkinson a., hill s.l., pakhomov e.a., siegel v., reiss c.s., loeb v.j., steinberg d.k., schmidt k., tarling g.a., gerrish l. & sailley s.f. 2019. krill (euphausia superba) distribution contracts southward during rapid regional warming. nature climate change 9, 142–147, doi: 10.1038/s41558-018-0370-z. atkinson a., shreeve r.s., hirst a.g., rothery p., tarling g.a., pond d.w., korb r.e., murphy e.j. & watkins j.l. 2006. natural growth rates in antarctic krill (euphausia superba): ii. predictive models based on food, temperature, body length, sex, and maturity stage. limnology and oceanography 51, 973–987, doi: 10.4319/lo.2006.51.2.0973. atkinson a., siegel v., pakhomov e. & rothery p. 2004. long-term decline in krill stock and increase in salps within the southern ocean. nature 432, 100–103, doi: 10.1038/nature02996. atkinson a., siegel v., pakhomov a.e., rothery p., loeb v., ross m.r., quetin b.l., schmidt k., fretwell p., murphy j.e., tarling a.g. & fleming h.a. 2008. oceanic circumpolar habitats of antarctic krill. marine ecology progress series 362, 1–23, doi: 10.3354/meps07498. barbosa a., benzal j., de león a. & moreno j. 2012. population decline of chinstrap penguin (pygoscelis antarctica) in deception island, south shetlands, antarctica. polar biology 35, 1453–1457, doi: 10.1007/s00300-012-1196-1. barlow k.e., boyd i.l., croxall j.p., reid k., staniland i.j. & brierley a.s. 2002. are penguins and seals in competition for antarctic krill at south georgia? marine biology 140, 205–213, doi: 10.1007/s00227-001-0691-7. barlow k.e. & croxall j.p. 2002a. seasonal and interannual variation in foraging range and habitat of macaroni penguins eudyptes chrysolophus at south georgia. marine ecology progress series 232, 291–304, doi: 10.3354/meps232291. barlow k.e. & croxall j.p. 2002b. provisioning behavior of macaroni penguins eudyptes chrysolophus. ibis 144, 248–258, doi: 10.1046/j.1474-919x.2002.00046.x. bearhop s., teece m.a., waldron s. & furness r.w. 2000. the influence of lipid and uric acid upon δ13c and δ15n values of avian blood: implications for trophic studies. the auk 117, 504–507, doi: 10.1093/auk/117.2.504. birdlife international 2019a. species factsheet. macaroni penguin eudyptes chrysolophus. accessed on the internet at http://datazone.birdlife.org/species/factsheet/macaroni-penguin-eudyptes-chrysolophus on 12 april 2019. birdlife international 2019b. species factsheet. chinstrap penguin pygoscelis antarcticus. accessed on the internet at http://datazone.birdlife.org/species/factsheet/chinstrap-penguin-pygoscelis-antarcticus on 12 april 2019. biuw m., lydersen c., de bruyn n.p.j., arriola a., hofmeyr g.j.g., kritzinger p. & kovacs k.m. 2010. long-range migration of a chinstrap penguin from bouvetøya to montagu island, south sandwich islands. antarctic science 22, 157–162, doi: 10.1017/s0954102009990605. blanchet m.-a., biuw m., hofmeyr g.j.g., de bruyn n.p.j., lydersen c. & kovacs k.m. 2013. at-sea behavior of three krill predators breeding at bouvetøya—antarctic fur seals, macaroni penguins and chinstrap penguins. marine ecology progress series 477, 285–302, doi: 10.3354/meps10110. calenge c. 2015. home range estimation in r: the adehabitathr package. r package version 04. statistics software accessed on the internet at http://www.cran.r-project.org on 15 may 2019. cherel y. & hobson k.a. 2007. geographical variation in carbon stable isotope signatures of marine predators: a tool to investigate their foraging areas in the southern ocean. marine ecology progress series 329, 281–287, doi: 10.3354/meps329281. cherel y., hobson k.a., bailleul f. & groscolas r. 2005. nutrition, physiology, and stable isotopes: new information from fasting and molting penguins. ecology 86, 2881–2888, doi: 10.1890/05-0562. clewlow h.l., takahashi a., watanabe s., votier s.c., downie r. & ratcliffe n. 2019. niche partitioning of sympatric penguins by leapfrog foraging appears to be resilient to climate change. journal of animal ecology 88, 223–235, doi: 10.1111/1365-2656.12919. cristofari r., liu x., banodonna f., cherel y., pistorius p., le maho y., raybaud v., stenseth n.c., le bohec c. & trucchi e. 2018. climate-driven range shifts of the king penguin in a fragment ecosystem. nature climate change 8, 245–251, doi: 10.1033/s41558-018-0084-2. croxall j.p. & davis l.s. 1999. penguins: paradoxes and patterns. marine ornithology 27, 1–12. croxall j.p., davis r.w. & o’connell m.j. 1988. diving patterns in relation to diet of gentoo and macaroni penguins at south georgia. the condor 90, 157–167, doi: 10.2307/1368444. dann p. & norman f.i. 2006. population regulation in little penguins (eudyptula minor): the role of intraspecific competition for nesting sites and food during breeding. emu 106, 289–296, doi: 10.1071/mu06011. davis l.s. & darby j.t. 1990. penguin biology. san diego, ca: academic press. de brooke m.l. 2004. the food consumption of the world’s seabirds. proceedings of the royal society of london b 271, 246–248, doi: 10.1098/rsbl.2003.0153. elliot k.h., woo k.j., gaston a.j., benvenuti s., dall’antonia l. & davoren g.k. 2009. central-place foraging in an arctic seabird provides evidence for storer-ashmole’s halo. the auk 126, 613–625, doi: 10.1525/auk.2009.08245. forcada j. & trathan p.n. 2009. penguin responses to climate change in the southern ocean. global change biology 15, 1618–1630, doi: 10.1111/j.1365-2486.2009.01909.x. gille s.t. 2002. warming of the southern ocean since the 1950s. science 295, 1275–1277, doi: 10.1126/science.1065863. green j.a., butler p.j., woakes a.j. & boyd i.l. 2002. energy requirements of female macaroni penguins at south georgia. functional ecology 16, 671–681, doi: 10.1046/j.1365-2435.2002.00670.x. haftorn s. 1986. a quantitative analysis of the behaviour of the chinstrap penguin pygoscelis antarctica and macaroni penguin eudyptes chrysolophus on bouvetøya during the late incubation and early nestling periods. polar research 4, 33–45, doi: 10.1111/j.1751-8369.1986.tb00516.x. hart t., mann r., coulson t., pettorelli n. & trathan p. 2010. behavioural switching in a central place forager: patterns of diving behaviour in the macaroni penguin (eudyptes chrysolophus). marine biology 157, 1543–1553, doi: 10.1007/s00227-010-1428-2. hindell m.a., robertson g.g. & williams r. 1995. resource partitioning in four species of sympatrically breeding penguins. in p. dann et al. (eds.): the penguins, ecology and management. pp. 196–215. chipping norton, australia: surrey beatty & sons. hobson k.a. & welch h.e. 1992. determination of trophic relationships within a high arctic marine food web using δ15n and δ13c analysis. marine ecology progress series 84, 9–18, doi: 10.3354/meps084009. hofmeyr g.j.g., krafft b.a., kirkman s.p., bester m.n., lydersen c. & kovacs k.m. 2005. population changes of antarctica fur seals at nyrøysa, bouvetøya. polar biology 28, 725–731, doi: 10.1007/s00300-005-0732-7. horswill c., trathan p.n. & ratcliffe n. 2017. linking extreme interannual changes in prey availability to foraging behavior and breeding investment in a marine predator, the macaroni penguin. plos one 12, e0184114, doi: 10.1371/journal.pone.0184114. ichii t., bengston j.l., boveng p.l., takao y., jansen j.k., hiruki-raring l.m., cameron m.f., okamura h., hayashi t. & naganobu m. 2007. provisioning strategies of antarctic fur seals and chinstrap penguins produce different responses to distribution of common prey and habitat. marine ecology progress series 344, 277–297, doi: 10.3354/mesps06873. inger r. & bearhop s. 2008. applications of stable isotope analyses to avian ecology. ibis 150, 447–461, doi: 10.1111/j.1474-919x.2008.00839.x. isaksen k., huyser o., kirkman s., wanless r. & wilson w. 2000. studies of seabirds and seals on bouvetøya 1998/99. norsk polarinstitutt internrapport 2. tromsø: norwegian polar institute. jackson a.l., inger r., parnell a.c. & bearho s. 2011. comparing isotopic niche widths among and within communities: siber—stable isotope bayesian ellipses in r. journal of animal ecology 80, 595–602, doi: 10.1111/j.1365-2656.2011.01806.x. jansen j.k., russell r.w. & meyer w.r. 2002. seasonal shifts in the provisioning behavior of chinstrap penguins, pygoscelis antarctica. oecologia 131, 306–318, doi: 10.1007/s00442-002-0880-1. johnson d.s., london j.m., lea m.-a. & durban j.w. 2008. continuous-time correlated random walk model for animal telemetry data. ecology 89, 1208–1215, doi: 10.1890/07-1032.1. kirkman s.p., wilson w., klages n.t.w., bester m.n. & isaksen k. 2000. diet and estimated food consumption of antarctic fur seals at bouvetøya during summer. polar biology 23, 745–752, doi: 10.1007/s003000000145. krafft a.b., melle w., knutsen t., bagøien e., broms c., ellertsen b. & siegel v. 2010. distribution and demography of antarctic krill in the southeast atlantic sector of the southern ocean during the austral summer 2008. polar biology 33, 957–968, doi: 10.1007/s00300-010-0774-3. lishman g.s. & croxall j.p. 1983. diving depths of the chinstrap penguin pygoscelis antarctica. british antarctic survey bulletin 61, 21–25. lowther a.d., lydersen c., biuw m., de bruyn n.p.j., hofmeyr g.j.g. & kovacs k.m. 2014. post-breeding at-sea movements of three central-place foragers in relation to submesoscale fronts in the southern ocean around bouvetøya. antarctic science 26, 533–544, doi: 10.1017/s0954102014000170. luque s.p. & fried r. 2011. recursive filtering for zero offset correction of diving depth time series with gnu r package divemove. plos one 6, e15850, doi: 10.1371/journal.pone.0015850. lynnes a.s., reid k., croxall j.p. & trathan p.n. 2002. conflict or co-existence? foraging distribution and competition for prey between adélie and chinstrap penguins. marine biology 141, 1165–1174, doi: 10.1007/s00227-002-0899-1. mcconnell b.j., chambers c. & fedak m.a. 1992. foraging ecology of southern elephant seals in relation to the bathymetry and productivity of the southern ocean. antarctic science 4, 393–398, doi: 10.1017/s0954102092000580. meyer a., polzin k.l., sloyan b.m. & phillips h.e. 2015. internal waves and mixing near the kerguelen plateau. journal of physical oceanography 46, 417–437, doi: 10.1175/jpo-d-15-0055.1. miller a.k., kappes m.a., trivelpiece s.g. & trivelpiece w.z. 2010. foraging-niche separation of breeding gentoo and chinstrap penguins, south shetland islands, antarctica. the condor 112, 683–695, doi: 10.1525/cond.2010.090221. miller a.k. & trivelpiece w.z. 2008. chinstrap penguins alter foraging and diving behavior in response to the size of their principle prey, antarctic krill. marine biology 154, 201–208, doi: 10.1007/s00227-008-0909-z. mori y. & boyd i.j. 2004. segregation of foraging between two sympatric penguin species: does rate maximisation make the difference? marine ecology progress series 275, 241–249, doi: 10.3354/meps275241. niemandt c., kovacs k.m., lydersen c., dyer b.m., isaksen k., hofmeyr g.g.j., mehlum f. & de bruyn n.p.j. 2016. chinstrap and macaroni penguin diet and demography at nyrøysa, bouvetøya. antarctic science 28, 91–100, doi: 10.1017/s0954102015000504. park y.h., fuda j.l., durand i. & naveira garabato a.c. 2008. internal tides and vertical mixing over the kerguelen plateau. deep-sea research part ii 55, 582–593, doi: 10.1016/j.dsr2.2007.12.027. petry m.v., valls f.c.l., petersen e.s., finger j.v.g. & krüger l. 2018. population trends of seabirds at stinker point, elephant island, maritime antarctica. antarctic science 30, 220–226, doi: 10.1017/s0954102018000135. polito m.j., reiss c.s., trivelpiece w.z., patterson w.p. & emslie s.d. 2013. stable isotopes identify an ontogenetic niche expansion in antarctic krill (euphausia superba) from the southern shetland islands, antarctica. marine biology 160, 1131–1323, doi: 10.1007/s00227-013-2182-z. polito m.j., trivelpiece w.z., patterson w.p., karnovsky n.j., reiss c.s. & emslie s.d. 2015. contrasting specialist and generalist patterns facilitate foraging niche partitioning in sympatric populations of pygoscelis penguins. marine ecology progress series 519, 221–237, doi: 10.3354/meps11095. post d.m. 2002. using stable isotopes to estimate trophic position: models, methods and assumptions. ecology 83, 703–718, doi: 10.1890/0012-9658(2002)083[0703:usitet]2.0.co;2. qgis development team 2019. qgis geographic information system. open source geospatial foundation project. statistics software accessed on the internet at http://www.qgis.osgeo.org on 15 march 2019. ratcliffe n., adlard s., stowasser g. & mcgill r. 2018. dietary divergence is associated with increased intra-specific competition in a marine predator. nature 8, article no. 6827, doi: 10.1038/s41598-018-25318-7. reid k. & croxall p.j. 2001. environmental response of upper trophic-level predators reveals a system change in an antarctic marine ecosystem. proceedings of royal society of london b 268, 377–384, doi: 10.1098/rspb.2000.1371. rombolá e.f., marschoff e. & coria n. 2010. inter-annual variability in chinstrap penguin diet at south shetland and south orkneys islands. polar biology 33, 799–806, doi: 10.1007/s00300-009-0757-4. scrucca l., fop m., murphy t.b. & raftery a.e. 2016. mclust 5: clustering, classification and density estimation using gaussian finite mixture models. the r journal 8, 289–317, doi: 10.32614/rj-2016-021. strycker n., wethington m., borowicz a., forrest s., witharana c., hart t. & lynch h.j. 2020. a global population assessment of the chinstrap penguin (pygoscelis antarctica). scientific reports 10, 19474, doi: 10.1038/s41598-020-76479-3. tarroux a., lowther a.d., lydersen c. & kit m.k. 2016. temporal shift in the isotopic niche of female antarctic fur seals from bouvetøya. polar research 35, 31335, doi: 10.3402/polar.v35.31335. thiebot j.-b., lescroël a., pinaud d., trathan p.n. & bost c.-a. 2011. larger foraging range but similar habitat selection in non-breeding versus breeding sub-antarctic penguins. antarctic science 23, 117–126, doi: 10.1017/s0954102010000957. thorpe s.e., murphy e.j. & watkins j.l. 2007. circumpolar connections between antarctic krill (euphausia superba dana) populations: investigating the roles of ocean and sea ice transport. deep-sea research part i 54, 792–810, doi: 10.1016/j.dsr.2007.01.008. tierney m., southwell c., emmerson l.m. & hindell m.a. 2008. evaluating and using stable-isotope analysis to infer diet composition and foraging ecology of adélie penguins pygoscelis adeliae. marine ecology progress series 355, 297–307, doi: 10.3354/meps07235. trathan p.n., garcía-borboroglu p., boersma d., bost c.-a., crawford r.j.m., crossin g.t., cuthbert r.j., dann p., davis l.s., de la puente s., ellenberg u., lynch h.j., mattern t., pütz k., seddon p.j., trivelpiece w. & wienecke b. 2015. pollution, habitat loss, fishing, and climate change as critical threats to penguins. conservation biology 29, 31–41, doi: 10.1111/cobi.12349. trivelpiece w.z., hinke j.t., miller a.k., reiss c.s., trivelpiece s.g. & watters g.m. 2011. variability in krill biomass links harvesting and climate warming to penguin population changes in antarctica. proceedings of the national academy of sciences of the united states of america 108, 7625–7628, doi: 10.1073/pnas.1016560108. trivelpiece w.z., trivelpiece s.g. & volkman n.j. 1987. ecological segregation of adelie, gentoo, and chinstrap penguins at king george island, antarctica. ecology 68, 351–361, doi: 10.2307/1939266. vaughan d.g., marshall g.j., connolley w.m., parkinson c., mulvaney r., hodgson d.a., king j.c., pudsey c.j. & turner j. 2003. recent rapid regional climate warming on the antarctic peninsula. climatic change 60, 243–274, doi: 10.1023/a:1026021217991. waluda c.m., collins m.a., black a.d., staniland i.j. & trathan p.n. 2010. linking predator and prey behaviour: contrasts between antarctic fur seals and macaroni penguins at south georgia. marine biology 157, 99–112, doi: 10.1007/s00227-009-1299-6. whitehead o.t., connan m., ropert-coudert y. & ryan p.t. 2017. subtle but significant segregation in the feeding ecology of sympatric penguins during the critical pre-moult period. marine ecology progress series 565, 227–236, doi: 10.3354/meps12017. williams t.d., briggs d.r., croxall j.p., naito y. & kato a. 1992. diving pattern and performance in relation to foraging ecology in the gentoo penguin, pygoscelis papua. journal of zoology 227, 211–230, doi: 10.1111/j.1469-7998.1992.tb04818.x. wilson r.p., pütz k., peters g., culik b., scolaro j.a., charrassin j.-b. & ropert-coudert y. 1997. long-term attachment of transmitting and recording devices to penguins and other seabirds. wildlife society bulletin 25, 101–106. wilson r.p. & wilson m.p. 1989. tape: a package attachment technique for penguins. wildlife society bulletin 17, 77–79, doi: 10.2307/3801309. engelskj.n.indd 317engelskjøn et al. 2003: polar research 22(2), 317–339 the archipelago of svalbard (74° 20' 80° 50' n) (fig. 1) is one of the world’s least impacted arctic biomes, and it is an aim for norwegian authorities to preserve it (stortinget 2000). a plan for vegetation protection has been proposed by the governor of svalbard (1999; see alsos 2000) because the prevailing practice of protecting plant species, but not their habitats, had evident shortcomings (thei sen & brude 1998; alsos 2000). the new plan (miljøverndepartementet 2003) is a supplement to the national park system of svalbard and implies protection of all plant life within circumscribed geographical areas (fig. 2). svalbard harbours approximately 165 native vascular plant species (elven & elvebakk 1996). the inner arctic fjord zone of spitsbergen (fig. 1) is particularly rich in species and is favoured by frequently clear skies and elevated summer temperatures (elvebakk 1985, 1989). between 20 and 30 of svalbard’s vascular plant species can be considered warmth-demanding compared to the rest of the archipelago’s fl ora (engel skjøn 1987; elvebakk 1989). their few, small and disjunct present-day populations are twenty of the most thermophilous vascular plant species in svalbard and their conservation state torstein engelskjøn, leidulf lund & inger greve alsos an aim for conservation in norway is preserving the svalbard archipelago as one of the least disturbed areas in the arctic. information on local distribution, population sizes and ecology is summarized for 20 thermophilous vascular plant species. the need for conservation of northern, marginal populations in svalbard is reviewed, using world conservation union categories and criteria at a regional scale. thirteen species reach their northernmost distribution in svalbard, the remaining seven in the western arctic. nine species have 1 8 populations in svalbard and are assigned to red list categories endangered or critically endangered: campanula rotundifolia, euphrasia frigida, juncus castaneus, kobresia simpliciuscula, rubus chamaemorus, alchemilla glomerulans, ranunculus wilanderi, salix lanata and vaccinium uliginosum, the last four species needing immediate protective measures. five species are classifi ed as vulnerable: betula nana, carex marina ssp. pseudolagopina, luzula wahlenbergii, ranunculus arcticus and ranunculus pallasii. six species are considered at lower risk: calamagrostis stricta, empetrum nigrum ssp. hermaphroditum, hippuris vulgaris (only occurring on bjørnøya), juncus triglumis, ranunculus lapponicus and rhodiola rosea. the warmer inner arctic fjord zone of spitsbergen supports most of the 20 target species and is of particular importance for conservation. endangered or vulnerable species were found in a variety of edaphic conditions; thus, several kinds of habitats need protection. t. engelskjøn, i. g. alsos, tromsø museum, university of tromsø, no-9037 tromsø, norway, torstein@ tmu.uit.no; l. lund, phytotron, university of tromsø, no-9037 tromsø, norway. 318 twenty thermophilous vascular plant species in svalbard partly relicts of larger populations thought to have been established between 9000 and 4000 years ago, when the mean july temperature was 1 2 °c higher than at present (birks 1991). the temp erature decline over the last 4000 years (birks 1991) may have suppressed sexual reproduction and caused fragmentation of popula tions and genetic bottlenecks (alsos, brochman et al. 2002; alsos et al. 2003). several thermophilous species rarely produce germinable seeds under the present climatic conditions and may thus have a reduced recruit ment following disturbance (nathorst 1883; alsos et al. 2003; cooper et al. in press). increased human activity in the most species-rich parts of sval bard (hansen et al. 1996; theisen & brude 1998) may constitute a threat to the thermo philous species of the archipelago. many records of these species are more or less buried in the literature. plant records prior to hadač (1944) were imprecise due to lack of topographical maps. in spite of svalbard having been frequently visited, documentation of uncommon species tended to be anecdotal. this paper is based on botanical surveys of bjørnøya (engelskjøn & schweitzer 1970; engelskjøn 1987), parts of spitsbergen (engelskjøn et al. 1972; hofmann & thannheiser 1972; thannheiser 1972; dubiel 1990; kuc & dubiel 1995; elven et al. 1990; möller & thannheiser 1997; möller 2000; alsos, lund et al. 2002), nordaustlandet (neilson 1968), edge øya (neilson 1970), barentsøya (hjelmstad 1981) and svalbard as a whole (elvebakk 1985, 1989; engelskjøn 1986; elven & elvebakk 1996), as well as our recent fi eld investigations. our aim is to assess the local distribution of 20 target species in relation to their presumed edaphic and thermal demands and their need of conservation measures to protect them. also considered are the southern geographical range extensions of some of these species and their mainly low alpine altitudinal limits in northern scandinavia (engelskjøn 1986, 1994). fig. 1. vegetation zones of svalbard, adapted from möller (2000). (the small island of bjørnøya, about 250 km south of the main groups of islands, is not shown.) 319engelskjøn et al. 2003: polar research 22(2), 317–339 study area svalbard is subdivided into provinces shown in fig. 3. also a part of the archipelago is the small island of bjørnøya, about midway between the norwegian mainland and the island of spitsbergen. methods inclusion of species apart from the 20 species treated here, at least 11 other vascular plant species in svalbard may be considered thermophilous, e.g. arctagrostis latifolia (rønning 1972), botrychium boreale, b. lunaria (elvebakk et al. 1994), arenaria humifusa, carex glacialis (elven & elvebakk 1996), carex bigelowii (elven & elvebakk 2002), cystopteris fragilis (rønning 1972), gentianella tenella (elvebakk 1989), juncus arcticus (lid 1925, 1967), taraxacum brachyceras (elvebakk 1989) and tofi eldia pusilla (rønning 1972). however, these rare species were insuffi ciently documented or not seen by us. conversely, at least two very rare species in svalbard are adapted to cold conditions, viz. ranunculus glacialis (elven & elvebakk 1996) and sagina caespitosa (lid 1962). phytogeographical terms zonal subdivision of svalbard follows möller (2000: 43) with respect to the inner arctic fjord zone of spitsbergen (fig. 1). in a circum-arctic context we use the phytogeographical terms presented in table 1. fig. 2. extant and proposed protected areas (national parks and nature reserves, excluding bird reserves) in svalbard, excluding bjørnøya. redrawn after governor of svalbard (1999) and miljøverndepartementet (2003). 320 twenty thermophilous vascular plant species in svalbard distribution, population sizes, and state of conservation populations of species are recorded in appendix 1 based on fi eld observations, botanical literature, norwegian university herbaria and personal communications. unpublished fi nds have been included. when more than one source reports the same fi nd, only the most precise one is quoted. estimates of population size are based on occurrence within the local 1 × 1 km square of the universal transverse mercator (utmed50) grid. populations are rated as small, medium or large, as delineated in table 1. the term “population” here also includes subpopulations belonging to the same metapopulation. red list categories are assessed according to the world conservation union (iucn 2001) at the regional scale of svalbard. the proportions of populations protected were reviewed according to extant and recently established protected areas (miljøverndepartementet 2003; fig. 2). ecology air temperatures for the growing season were compiled from climatological literature and from engelskjøn (1986, 1987, 1994). notes are provided on mineral and/or organic substrata and hydrology of the habitats of each species. accompanying species are enumerated; nomenclature mainly follows elvebakk & hertel (1996), elven & elvebakk (1996), frisvoll & elvebakk (1996) and gulden & torkelsen (1996). fig. 3. thermophilous species per province in svalbard (bjørnøya not shown), given as the number of species / total number of observed populations of all 20 target species. see fig. 1 for vegetation zones. table 1. defi nitions of phytogeographical terms and population size categories used in this paper. term defi nition boreal the northern, wooded latitudinal zone. arctic the entire or most of the treeless zone. low arctic southern portion of the arctic, with prominent betula nana, medium-sized salix spp., ledum palustre, vaccinium spp. or empetrum spp., corresponding to elvebakk’s (1985) low arctic tundra zone. high arctic northern portion of the arctic, i.e. all lands north of the low arctic. barents sea region svalbard, franz josef land, novaya zemlya, vaygach, kolguyev and the polar urals. small population a closed stand less than 15 × 15 m; alternatively, scattered individuals or ramets within only one quarter of the 1 km utm square. medium population one or a few copious stands at least 15 × 15 m, or scattered individuals/ramets in more than one quarter of the 1 km utm square. large population generally distributed and/or abundant within one or more 1 km utm squares. no data no precise information is available on population size. 321engelskjøn et al. 2003: polar research 22(2), 317–339 results table 2 summarizes worldwide northern limits, number of populations in svalbard, and tentative red list categories. a more detailed account is provided in appendix 1, which also specifi es populations protected under the current conservation plan for svalbard (miljøverndepartementet 2003). state of conservation red list categories are recorded in table 2. nine species are considered endangered or critically endangered in svalbard; fi ve species are vulnerable, and six species are at lower risk. according to the current protection plan, more than half of the known svalbard populations of the following species are protected: alchemilla glomerulans, calamagrostis stricta, carex marina ssp. pseudolagopina, empetrum nigrum ssp. hermaphroditum, hippuris vulgaris, juncus castaneus, luzula wahlenbergii, ranunculus arcticus, r. wilanderi, rhodiola rosea, and rubus chamaemorus. fewer than half of the populations of euphrasia frigida, juncus triglumis, kobresia simpliciuscula, ranunculus lapponicus, r. paltable 2. twenty thermophilous species in svalbard. population data from appendix 1. species extant northern limit in svalbard northern limit outside of svalbard no. of popula tions % of pop ulations protected red list category at the regional level (iucn 2001) alchemilla glomerulans sam. 74° 31' bjørnøya 71° 10' nordkapp, mainland norway (dahl 1934) 1 100 critically endangered betula nana l. 78° l5' adventdalen 76° ne greenland (fredskild 1998) 39 0 vulnerable calamagrostis stricta (timm) koeler 79° 30' liefdefjorden 74° 40' ne greenland (bay 1992) 108 53 lower risk campanula rotundifolia l. 78° 07' colesbukta 75° 50' ne greenland (bay 1992) 4 0 endangered carex marina dew. ssp. pseudolagopina (sørensen) böcher 79° 30' liefdefjorden 83° n greenland (bay 1992) 16 100 vulnerable empetrum nigrum l. ssp. hermaphroditum (hagerup) böcher 80° 30' nordaustlandet 79° 10' nw greenland (simmons 1909) ca. 80 54 lower risk euphrasia frigida pugsley 79° 26' bockfjorden 77° 20' ne greenland (bay 1992) 7 28 endangered hippuris vulgaris l. 74° 31' bjørnøya 82° 13' n greenland (fredskild 1966) 22 100 lower risk juncus castaneus sm. 78° 28' gipsdalen 83° n greenland (bay 1992) 5 60 endangered juncus triglumis l. 79° 30' wijdefjorden 83° n greenland (bay 1992) 39 41 lower risk kobresia simpliciuscula (wahlenb.) mack. 78° 56' kongsfjorden 82° 01' n greenland (holmen 1957) 8 38 endangered luzula wahlenbergii rupr. 78° 17' adventfjorden 75°55' ne greenland (bay 1992) 14 50 vulnerable ranunculus arcticus r. br. 79° 15' krossfjorden 83° n greenland (bay 1992) 25 84 vulnerable ranunculus lapponicus l. 79° wijdefjorden 73° novaya zemlya (lynge 1924) 70 41 lower risk ranunculus pallasii schlecht. 78° 25' bohemanfl ya 73° novaya zemlya (lynge 1924) 11 45 vulnerable raunculus wilanderi (nath.) á. & d. löve 78° 27' kapp thordsen 73° novaya zemlya (lynge 1924 – sp.?) 1 100 critically endangered rhodiola rosea l. 78° 45' prins karls forland 75° 05' ne greenland (bay 1992) 30 100 lower risk rubus chamaemorus l. 78° 38' ekmanfjellet 73° novaya zemlya (lynge 1924) 9 67 endangered salix lanata l. 78° 12' adventdalen 75° taymyr (tolmachev et al. 1996) 2 0 extirpated (kongsfjorden); critically endangered (adventdalen) vaccinium uliginosum l. 78° 39' mimerdalen 81° 55' n greenland (holmen 1957) 5 20 critically endangered 322 twenty thermophilous vascular plant species in svalbard lasii, and vaccinium uliginosum are protected. none of the populations of betula nana or campanula rotundifolia, nor the only intact population of salix lanata, are protected. impact of climate air temperatures and heat sums for july–august and june–september are summarized for boreal or arctic stations in northern norway and svalbard (table 3). the island of hopen has a comparably cold climate, summer temperatures reaching only a few degrees above zero. the climate at the southern end of spitsbergen, represented by hornsund, is comparable to isfjord radio and bjørnøya. there is a sizeable difference in summer temperature between the coastal station isfjord radio, on the margin of the middle arctic tundra zone, and the longyearbyen station in the inner arctic fjord zone (fig. 1): degree-days (sum of mean diurnal temperatures) for july– august amount to 290 and 365, respectively. the thermophilous species in svalbard generally require a heat sum exceeding 300 degree-days for july and august. the occurrence of these species in various parts of spitsbergen is illustrated in fig. 3. edaphic requirements based on observations in the fi eld, preferences of soil and hydrology are outlined for the 20 target species (table 4). there is a considerable variation along the gradients eutrophic—oligotrophic and drained—wet. review of species thirteen thermophilous species advance farther north in svalbard than in other arctic lands (table 2). seven species occurring in svalbard reach their northern limits in greenland: carex marina ssp. pseudolagopina, hippuris vulgaris, juncus castaneus, j. triglumis, kobresia simpliciuscula, ranunculus arcticus and vaccinium uliginosum. the following 20 target species are treated in some detail with regard to their distribution table 4. twenty thermophilous vascular plant species in svalbard according to edaphic gradients. drained moist wet calcareous (eutrophic) (none) alchemilla glomerulans kobresia simpliciuscula carex marina ssp. pseudolagopina juncus castaneus juncus triglumis mixed or intermediate (mesotrophic) betula nana campanula rotundifolia ranunculus arcticus rhodiola rosea vaccinium uliginosum euphrasia frigida ranunculus wilanderi salix lanata calamagrostis stricta hippuris vulgaris ranunculus lapponicus ranunculus pallasii siliceous or humic (oligotrophic) empetrum nigrum ssp. hermaphroditum rubus chamaemorus luzula wahlenbergii (none) table 3. temperatures (°c) and heat sums for the summer in svalbard. standard normals 1931–1960, if not otherwise stated. data from steffensen (1982) and baranowski (1975). see also aune (1993) for standard normals 1961–1990. data for tromsø and vardø, northern norway, included for comparison. northern latitude mean temperature (°c) degree-days jun. jul. aug. sept. jul.–aug. jun.–sept. tromsø 69° 39' 9.4 12.6 11.5 7.7 747 1260 vardø 70° 22' 6.3 9.3 9.8 6.8 590 983 bjørnøya 74° 31' 2.0 4.5 5.0 3.0 295 445 hopen (1946–1965) 76° 30' –0.4 2.0 2.2 0.9 130 157 hornsund (1970–74) 76° 50' 2.2 5.3 4.8 1.7 315 432 isfjord radio 78° 06' 1.8 4.9 4.4 1.3 290 383 longyearbyen 78° 12' 2.9 6.5 5.3 1.0 365 482 323engelskjøn et al. 2003: polar research 22(2), 317–339 and ecology in svalbard (table 2; appendix 1). alchemilla glomerulans the species occurs at one locality on bjørnøya (engelskjøn 1987: 103–104), which is also its northern limit. the nearest occurrences are on jan mayen (lid 1964: 54) and at nordkapp (north cape) (dahl 1934: 357). in 1983 three individuals (clones) were found in a sheltered gully on the northern coast of bjørnøya with the bryophytes brachythecium refl exum, dichodontium pellucidum, philonotis tomentella, sanionia uncinata, syntrichia ruralis and timmia austriaca and the vascular species cerastium arcticum, c. cerastoides, festuca rubra ssp. arctica, oxyria digyna, ranunculus pygmaeus and saxifraga cernua. growing at a slightly disturbed site in the vicinity of the bjørnøya meteorological station, a. glomerulans might have been introduced accidentally there. however, the species occurs in natural vegetation and may be native to bjørnøya. see the distribution map in engelskjøn (1987: 126). betula nana the species is confi ned to south of isfjorden (nathorst 1871: 113; andersson 1910: 411; resvoll-holmsen 1913: 26, 53). at colesdalen it occurs up to 210 m asl (alsos, lund et al. 2002); at adventdalen, to 140 m asl (engelskjøn, unpubl. data). only seven among 39 populations were rated as large. seed reproduction has not been observed in germination experiments (misund 1997) or seed bank studies (alsos et al. 2003; cooper et al. in press). betula nana occupies depressions on welldrained, south-facing hillsides. it is associated with cassiope tetragona and dryas octopetala (table 14 in lid 1967) and in places also with empetrum nigrum ssp. hermaphroditum or hierochloë alpina (engelskjøn & spjelkavik 1999). the mushroom, leccinum rotundifoliae (fig. 3 in engelskjøn & spjelkavik 1999), forms mycorrhiza with dwarf birch (gulden & torkelsen 1996: 190) and appears as an indicator of low arctic vegetation. this is a polymorphic species, which seems to comprise several subspecifi c taxa (hultén & fries 1986), and probably includes the northern b. tundrarum perfi lyev (tolmachev 1976). de groot et al. (1997: 253) summarized some taxonomic proposals on b. nana. see distribution maps in engelskjøn (fig. 5 in 1986) and elvebakk (fig. 27 in 1989). see local maps in hadač (fig. 10 in 1944), engelskjøn & spjelkavik (fig. 1 in 1999) and alsos, lund et al. (2002). calamagrostis stricta on bjørnøya this grass is often sterile but may develop culms up to 15 cm tall in late august. on spitsbergen c. stricta is characteristic of riverbanks with culms up to 27 cm in early august. it is rare in the calcareous valley of sassendalen and absent on the alkaline soils of eskerdalen (engelskjøn, unpubl. data) and gips dalen (elven et al. 1990). twelve large populations were recorded in the inner arctic fjord zone; otherwise the rather numerous populations are medium-sized (32) or small (21). on bjørnøya c. stricta associates, for example, with dupontia psilosantha, equisetum ar vense, festuca rubra, poa pratensis ssp. alpigena and, rarely, with cardamine pratensis ssp. polemonioides, carex subspathacea, equisetum vari egatum or saxifraga cernua. on spitsbergen the species inhabits mesotrophic to eutrophic mires, associating with cardamine pratensis ssp. polemonioides, colpodium vahlianum, dupontia spp. and eriophorum scheuchzeri. most svalbard specimens resemble c. holmii lange with short, dark panicles (see hultén 1968: 107, 1973: 465). see distribution maps in rønning (map 18 in 1972), elvebakk (fig. 64 in 1989). see local maps in hadač (fig. 36 in 1944) and engelskjøn (1987: 115). table 5. abbreviations of herbaria mentioned in this paper, in accordance with holmgren et al. (1990). some of the institutional names have been updated. bg botanical institute, university of bergen, norway c botanical museum, university of copenhagen, denmark cge botany school, university of cambridge, uk o botanical museum, university of oslo, norway trh dept. of botany, university of trondheim (ntnu), norway trom dept. of botany, tromsø university museum, norway 324 twenty thermophilous vascular plant species in svalbard campanula rotundifolia the species is confi ned to colesbukta and colesdalen, spitsbergen. it was discovered in 1915 (asplund 1919: 36) and fl owering started on l3 august that year (specimens in herbarium o; see table 5). this is probably the population of c. rotundifolia located on a hill facing colesbukta, extending over 104 m2. flowering started on 15 july in the exceptionally warm summer of 1998, in mid-august 1999 and at the end of july 2002. two additional, small populations were found on the northern side of colesdalen, succeeded towards the interior by a nearly continuous, large population extending over approximately 2600 × 400 m. no germinable seeds or seed bank have been observed (alsos et al. 2003; cooper et al. in press). campanula rotundifolia grows on sandstone lithosol with rock gaps and some turf with mesotrophic species such as betula nana, draba daurica, dryas octopetala, poa glauca and polemonium boreale as well as the ubiquitous bistorta vivipara, luzula arcuata ssp. confusa and salix polaris. we noted the scarcity of calciphilous species such as carex rupestris and saxifraga oppositifolia, which may be explained by the low amounts of calcium carbonate in the bedrock (major & nagy 1966). the occurrence of trisetum spicatum suggests some protection by relatively late-lying snow. situated 0.4 to 4 km away from the former colesbukta mining settlement, the occurrences of c. rotundifolia have remained intact up to the present and are still nearly undisturbed by human activity. flovik (1940) found that colesbukta plants are diploid (2n = 34). diploid c. rotundifolia may be given the rank of subspecies or species c. giesekiana vest (böcher 1960; gadella 1964; laane 1968; croff 1978; shetler 1982). see distribution map in alsos, lund et al. (2002). carex marina ssp. pseudolagopina first found in sassendalen (by nathorst in 1882; herbarium c), but misinterpreted as carex lagopina (= c. lachenalii ), this taxon was rediscovered on spitsbergen 80 years later (schweitzer 1966: 147 and his fig. 2) and then referred to the synonymic c. amblyorhyncha v. krecz. in accordance with böcher (1952; see halliday & chater 1969). carex marina ssp. pseudolagopina is frequent at mires and ponds in sassendalen and gipsdalen, 3 50 m asl, whereas stations in dickson land and at liefdefjorden are few. occurrences apparently depend on calcareous substrata with suffi cient moisture. the species carex marina associates with cinclidium arcticum, meesia uliginosa, ortho thecium chryseon, scorpidium cossonii, tomen typ num nitens, cardamine pratensis ssp. polemoni oides, carex maritima, c. parallela, c. sax atilis, c. sub s pathacea, equisetum arvense ssp. boreale, e. variegatum, eriophorum triste, eu trema edwardsii and juncus triglumis. böcher (1952: 30) pointed out the slightly halophilous and calciphilous character of c. marina (as c. amblyorhyncha) in greenland. see distribution maps in böcher (fig. 12 in 1952), rønning (map 25 in 1972), engelskjøn (fig. 6 in 1986) and elvebakk (fig. 67 in 1989). empetrum nigrum ssp. hermaphroditum discovered at grønfjorden (fries 1869; cf. elvebakk & spjelkavik 1995: 544), empetrum is frequent at isfjorden (engelskjøn & spjelkavik 1999), less so at bellsund and van mijenfjorden (engelskjøn et al. 1972). it is frequent in dickson land (högbom 1913; möller & thannheiser 1997), inner kongsfjorden and liefde fjorden, but is rare in northern svalbard (elvebakk & spjelkavik 1995; möller 2000), including nordaustlandet, at 80.5° n (brattbakk 1981 cited in elvebakk & spjelkavik 1995). empetrum ascends to approximately 200 m asl (hadač 1944: 55). only nine populations among approximately 80 are considered large. ripe fruits were recorded in the middle of august at van mijenfjorden (holmboe 1910), on 4 september at grønfjorden (wirén 1922), in september at mimerdalen (högbom 1913: 153, his fig. 1) and on 30 july in the warm summer of 1998. collections from various parts of spitsbergen bear unripe fruits that could well have reached maturity, but seed reproduction of empetrum in svalbard has not been observed in seed bank studies (alsos et al. 2003; cooper et al. in press). empetrum associates with betula nana south of isfjorden (engelskjøn & spjelkavik 1999). it is acidiphilous (elvebakk & spjelkavik 1995; möller 2000) but was also observed on slightly calcifer325engelskjøn et al. 2003: polar research 22(2), 317–339 ous substrata: at berzeliusdalen with dryas octopetala in a carpet of racomitrium canescens coll. and at lower reindalen with cassiope tetragona, dryas octopetala, hierochloë alpina and sparse carex rupestris. in the middle part of reindalen empetrum occurs on peaty banks with sphagnum aongstroemii, tomentypnum nitens, cassiope tetragona and salix polaris. svalbard plants are tetraploid with 2n = 52 (flovik 1940; engelskjøn 1979) and monoecious. e. hermaphroditum hagerup, which is invariably tetraploid and has a northern distribution, was treated as a species (fredskild 1998) or as a subspecies (hultén 1968; böcher et al. 1978). see distribution maps in elvebakk (fig. 67 in 1989) and elvebakk & spjelkavik (fig. 2 in 1995). see local maps in hadač (fig. 11 in 1944) and elvebakk & spjelkavik (figs. 4, 5 in 1995). euphrasia frigida this annual plant was discovered at bockfjorden by skifte (1960, trom, see rønning 1961; elvebakk & spjelkavik 1981). in 1998 e. frigida was found some 150 km farther south, in colesdalen (alsos & lund 1999), and in 2003 a 1 × 2 m patch was found at ossian sarsfjellet, kongs fjorden (trom). the nearest occurrences are at 71° n on jan mayen (lid 1964: 60) and at nordkapp (dahl 1934: 382). detailed fl ora studies in colesdalen in 2002 revealed small patches and scattered individuals of e. frigida within nine 100 × 100 m squares. three habitats were located north of the settlement at colesbukta, the remaining ones in the south-facing, northern valley slope approxi mately 2 km landward. the largest stand observed was 10 × 70 m, but most were a few square metres (alsos, lund et al. 2002). rønning (1961: 11) reported euphrasia “in the hollows near the hot springs where the soil temperature is high”. at colesbukta and in colesdalen e. frigida grows in salix polaris communities; in colesdalen it also grows with bistorta vivipara, festuca rubra ssp. arctica and trisetum spicatum, indicating eutrophic and snow-protected conditions (fig. 1 in alsos & lund 1999). there is no geothermal heat at the kongsfjorden and colesbukta sites. see distribution map in elvebakk (fig. 11 in 1989). see local map in alsos, lund et al. (2002). hippuris vulgaris this aquatic species is confi ned to shallow pools on bjørnøya (engelskjøn 1987). the northernmost station of h. vulgaris is in north greenland, 82° 13' (map no. 150 in bay 1992), whereas the stations closest to bjørnøya are nord kapp (71° 7' 8', dahl 1934) and karmakula in novaya zemlya (72° 24' n, lynge 1924: 129). two bjørnøya populations are rated as large; elsewhere they are medium-sized or small. hippuris grows in carpets of straminergon stramineum or warnstorfi a tundrae, accompanied by cardamine pratensis ssp. polemonioides, dupontia psilosantha, equisetum arvense ssp. boreale, ranunculus hyperboreus and saxifraga rivularis. see the distribution map in engelskjøn (1987: 127). juncus castaneus the northernmost representatives are located in north greenland (fredskild 1966; bay 1992). on spitsbergen j. castaneus is restricted to gipsdalen, sassendalen and a few places south of isfjorden. the drawing in rønning (fig. 39b in 1996) is not representative since the selected culm carries only undeveloped (aborted?) capsules. the stand at gipsdalen is very local (eriksen norberg, pers. comm. 1999), growing on calcareous mud with scorpidium cossonii. according to schweitzer (1966: 147), j. castaneus associates with ranunculus × spetsbergensis at de geerdalen. one collection from longyeardalen consisted of 12 culms with half-ripe capsules as of 6 august 1924. to our knowledge this locality has not been seen recently and the plants may have been extirpated. see distribution maps in rønning (map 11 in 1972) and elvebakk (fig. 17 in 1989). juncus triglumis the species occurs in one place at recherchefjorden and more frequently around isfjorden, kongsfjorden and wijdefjorden, inhabiting calcareous fens from 5 to 70 m asl and associating with cinclidium sp., loeskypnum badium, orthothecium chryseon, paludella squarrosa, scorpidium cossonii, s. turgescens, carex marina ssp. pseudolagopina, c. parallela, c. saxatilis, 326 twenty thermophilous vascular plant species in svalbard eutrema edwardsii and (rarely) kobresia simpliciuscula. the variety albescens lange has been identifi ed from svalbard. it is regarded as a subspecies by some authors (elvebakk 1989; elven 1994; elven & elvebakk 1996; rønning 1996). others found the varieties of j. triglumis vaguely circumscribed (sørensen 1933: 159–161; jørgensen et al. 1958: 47–48). the geographical ranges of ssp. triglumis and ssp. albescens are overlapping according to hultén & fries (1986). see distribution maps in rønning (map 10 in 1972) and elvebakk (fig. 18 in 1989). see local map in hadač (fig. 36 in 1944). kobresia simpliciuscula two stations were reported at the inner branches of isfjorden: mimerdalen, 2 km from the sea (lid 1925: 316) and gipsdalen, 10 20 m asl (engelskjøn 1986) as well as one at kongsfjorden, 50 130 m asl (elvebakk 1993). with approximately 10 tufts, the gipsdalen population is small. the population at mimerdalen needs investigation, whereas at least one of the populations at kongsfjorden (elvebakk 1993) appears as medium-sized (elvebakk 1993: 251, 253; specimens in trom). at mimerdalen k. simpliciuscula occurred with carex parallela and juncus triglumis (lid 1925), and the specimens are admixed with scorpidium cossonii, an indicator of calcareous substratum (elvebakk 1993: 250; frisvoll & elvebakk 1996: 114). at gipsdalen k. simpliciuscula grew on calcareous mud accompanied by orthothecium chryseon, scorpidium cossonii, bistorta vivi para, carex marina ssp. pseudolagopina, carex parallela, c. saxatilis, eutrema edwardsii, juncus bi glumis, j. triglumis, the ubiquitous salix polaris and some draba oxycarpa, dryas octopetala and saxifraga hirculus. at kongsfjorden kobresia occurred on calcareous substrata, as indicated by the admixed ditrichum fl exicaule, hypnum bambergeri, scorpidium turgescens, tomentypnum nitens, juncus triglumis and tofi eldia pusilla. the fens with k. simpliciuscula were “dominated by carex saxatilis” (elvebakk, note on herbarium label). in 2001 and 2002 four small populations of kobresia simpliciuscula were discovered in adolf bukta (in bünsow land) and at wijdefjorden (ny-friesland) (elvebakk, pers. comm. 2002). details on these localities will be given by elvebakk et al. (in prep.). see distribution maps in rønning (map 18 in 1972), engelskjøn (fig. 7 in 1986) and elvebakk (1993). luzula wahlenbergii the fi rst fi nd in svalbard was at bjørndalen (nathorst 1883: 37) and subsequent fi nds are all from the siliceous parts of nordenskiöld land and nathorst land, not above 50 m asl. only one among 14 populations may be rated as mediumsized; otherwise they are small. luzula wahlenbergii associates with oncophorus wahlenbergii, sphagnum aongstroemii, s. teres, straminergon stramineum, warnstorfi a sarmentosa, calamagrostis stricta, petasites frigidus and ranunculus pallasii. tundra mires structured by bryophytes are vulnerable to roadbuilding and terrain wear, for instance at reindalen (spjelkavik 1991). although being threatened by local road construction, l. wahlenbergii was found within the longyearbyen settlement as late as 1996 (brosø, pers. comm. 1997). see distribution maps in rønning (map 13 in 1972) and elvebakk (fig. 30 in 1989). ranunculus arcticus ranunculus arcticus is dispersed in svalbard from edgeøya (neilson 1970: 35, as r. pedatifi dus) and sørkapp (south cape) northwards to krossfjorden. it occupies sunny promontories to 230 m asl at sassenfjorden (elvebakk & hodin 1985, trom). neilson (1970) found the species co-dominant at a bird rookery on edgeøya, but we believe most r. arcticus populations are small. a characteristic inhabitant of south-exposed hills with f. rubra ssp. arctica, r. arcticus associates with less common species such as draba arctica, d. norvegica, festuca baffi nensis, polemonium boreale, potentilla hyparctica, p. ×insularis, silene furcata, taraxacum arcticum and t. brachyceras. simmons (1906: 101–108) and lynge (1924: 35 and pl. xxi) discuss the nomenclature of r. affi nis / r. arcticus (see ericsson 2001: 256). the related r. pedatifi dus sm., to which the svalbard plants were referred in earlier treatments, originates from the mid-latitude altay mountains (hadač 1944). see the distribution map in elvebakk (fig. 53 in 327engelskjøn et al. 2003: polar research 22(2), 317–339 1989). see local map in hadač (fig. 50 in 1944). ranunculus lapponicus the species extends from bromelldalen south of van mijenfjorden northwards to wijdefjord en (nathorst 1883), from 5 m upwards to 130 m asl. a record of r. lapponicus from edgeøya (michelmore 1934) is not documented (see dahl 1937: 25). among 37 local populations of known size we consider only two as large (appendix 1). in adventdalen, colesdalen and reindalen ranunculus lapponicus occurs in bryophyte communities of aulacomnium palustre, a. turgidum, onco phorus wahlenbergii, paludella squar rosa, sphagnum fi mbriatum, s. squarrosum, s. teres, sanionia uncinata, tomentypnum nitens or warnstorfi a tundrae. it associates with carex subspathacea, dupontia fi sherii, equisetum arvense ssp. boreale, petasites frigidus (table 20 in lid 1967), ranunculus hyperboreus, r. ×spetsbergensis, r. pallasii and salix polaris. see distribution maps in engelskjøn (fig. 8 in 1986) and elvebakk (fig. 52 in 1989). see local map in hadač (fig. 53 in 1944). ranunculus pallasii the species is known from reindalen, extending 21 km inland and upwards to 70 m asl, and from a few places at isfjorden (hadač 1944), reaching 100 m asl at interior colesdalen (engelskjøn & spjelkavik 1999). records of r. pallasii prior to nathorst (1883: 21) partly include r. ×spetsbergensis, and those from hornsund (triloff 1944: 292) and prins karls forland (brown 1908: 315) probably refer to the latter. the rhizomes are immersed during the fi rst half of summer. characteristic accompanying species are scapania sp., sphagnum squarrosum, warnstorfi a exannulata, w. fl uitans, w. sarmentosa, ranunculus lapponicus, r. ×spetsbergensis and carex subspathacea. on the reindalsletta plain, 6 august 1985, we observed the drying out of the pools harbouring r. pallasii. see distribution maps in engelskjøn (fig. 9 in 1986) and elvebakk (fig. 31 in 1989). ranunculus wilanderi restricted to a boggy plain inside kapp thordsen at isfjorden, r. wilanderi was fi rst observed, but not named, by nathorst (1871). in his original description nathorst (1883: 23–24) recorded it “in two places” at kapp thordsen, whereas the population was considered as “fairly extensive” by elven & elvebakk (1996: 40). plants apparently numbered not more than 20 in 1996. they were confi ned to runnels between a dolerite cliff with ranunculus arcticus and a sphagnum moor with abundant, sterile rubus chamaemorus. described as r. affi nis *wilanderi, this is a member of the r. auricomus complex (ericsson 2001: 237 and his fig. 105b), apparently close to var. glabrata lynge (1924: 35–36, pl. xxii). the latter was described from novaya zemlya, and subsequently identifi ed from north-eastern greenland (sørensen 1933: 53–54). var. glabrata was ranked as a species r. glabratus by fagerström & kvist (1983). fig. 4. salix lanata from adventdalen, svalbard. (a) male individual cultivated at tromsø botanic gardens. photo: i. g. alsos (4 may 2002). (b) twig of cloned offspring cultivated in the phytotron (t 15 °c; 24 hrs daylight), 1998—2002. note the stipules. photo: l. lund (march 2002). (a) (b) 328 twenty thermophilous vascular plant species in svalbard rhodiola rosea the species was fi rst discovered in svalbard by keilhau (1831) on his pioneer visit to bjørnøya. this island has most of rhodiola in svalbard (engelskjøn & schweitzer 1970; engelskjøn 1987). two large populations inhabit the cliffs and promontories of the north-eastern and south-western coasts; otherwise the species is scattered with a few individuals. occurrences on prins karls forland (brown 1908: 318), including richardlaguna (rønning, pers. comm. 1985), need further study. pollen of rhodiola has been found in droppings of incubating barnacle geese at lovénøyane islands in kongsfjorden (alm & alsos, unpubl. data 1999), suggesting that the species also may occur in that area. growing near the coastal brink of bjørnøya, rhodiola prefers bedrock of kulm sandstone and associates with cochlearia groenlandica, draba norvegica, festuca rubra ssp. arctica, f. vivi para and poa pratensis ssp. alpigena. there is also a rhodiola–luzula arcuata community. the broad-leaved, dwarfed svalbard strain (fig. 9 in engelskjøn & schweitzer 1970) is referable to ssp. arctica (a. boriss.) á. & d. löve (borissova 1939: 30–31, 171–172). see the distribution map in elvebakk (fig. 33 in 1989). see local map in engelskjøn (1987: 124). rubus chamaemorus rubus chamaemorus is restricted to moors near isfjorden. one stand at kapp thordsen measures at least 50 × 50 m and is rated as mediumsized. due to lack of fl owers in 1996, the local proportion of pistillate / staminate plants is unknown. at rusanovodden, near colesbukta, south of the rusanov hut, there were (in 1998) four stands (with staminate fl owers), measuring 6 × 9 m; 4 × 8 m; 2 × 4 m, and 6 × 7 m, as well as (in 2002) two stands (with pistillate fl owers), measuring 5 × 20 m and 20 × 20 m. one stand north of the rusanov hut, not fl owering in 2002, covered approximately 100 m2. at colesdalen, near the cemetery south-east of the former mining settlement, two patches of staminate plants were found, each 6 × 6 m (alsos, lund et al. 2002). two pistillate stands below ekmanfjellet were both approximately 10 × 3 m, and a staminate one at the river hemsil was 9 × 11.5 m in 1998. at sveasletta, west of ekmanfjorden, one stand exceeded 10 × 10 m (wirén 1922; hauge, pers. comm. 1998). flowering has been observed at most localities, but seed set is weak because of the prevailing unisexual clones. ripe fruits were recorded at sveasletta in the warm season of 1998 (hauge, pers. comm. 1998). the stands at kapp thordsen are on peat, mainly of sphagnum fi mbriatum. at rusanovodden rubus chamaemorus associates with aulacomnium turgidum, dicranum laevidens, polytrichum strictum, sphagnum aongstroemii or s. squarrosum, betula nana and luzula arcuata ssp. confusa. at colesdalen rubus occurs in mesotrophic bryophyte carpets. the stands west of ekmanfjorden support cassiope tetragona and a number of lichen species, e.g. pilophorus robustus, suggesting rather dry conditions. see the distribution map in elvebakk (fig. 22 in 1989). see local map in alsos, lund et al. (2002). salix lanata one spitsbergen occurrence of a disputed salix sp. is located on the northern brink of adventelva, wsw of the helvetia pingo (innerhytta). it was discovered by schweitzer in 1963 (see hultén 1964; schweitzer 1966). the juvenile, sparse material was fi rst identifi ed by hultén as s. glauca l. ssp. callicarpaea (trautv.) böcher (see hultén 1958, 1964). we have studied this occurrence in 1986, 1998 and 2001. four small clones were permanently established over an area of 10 × 30 m. only staminate catkins developed in the fi eld and in cultivation at tromsø botanic gardens (fig. 4a). the adventdalen salix grows in bryophyte carpets, mainly of tomentypnum nitens, together with alopecurus borealis, calamagrostis stricta, equisetum arvense ssp. boreale, poa pratensis ssp. alpigena, bistorta vivipara and salix polaris. patches of dryas octopetala occurred on drier parts of the moist, sloping terrace, which is subjected to river undercutting and may become destroyed in the course of a few decades. elven & elvebakk (1996: 41) reported another medium-sized salix (as s. arctica) from nyålesund. that individual was extirpated in 1990 /1991 according to a note on the herbarium label by o. i. rønning. we have studied material collected in 1974 and (as a dead twig) in 1991 (trh), and a colour photograph from 1976 (elvebakk, pers. comm. 2002), to compare it with the adventdalen plants. in elvebakk’s photograph 329engelskjøn et al. 2003: polar research 22(2), 317–339 the sterile salix sp. is seen with bistorta vivipara, salix polaris and saxifraga oppositifolia. propagation of a twig transplanted from the adventdalen salix in 1998 (fig. 4b) did not confi rm hultén’s original identifi cation of it as s. glauca ssp. callicarpaea, nor as s. arctica proposed by elven (1994), elven & elvebakk (1996), rønning (1996) and elven & karlsson (2000: 141). its identifi cation as s. lanata was suggested by george argus, leading salicologist of north america, who has examined photographs and herbarium specimens from adventdalen (pers. comm. 2002). this is corroborated by leaf morphology and venation, well-developed stipules (fig. 4b), pale yellowish indumentum of shortpedunculate catkins, yellow anthers and glabrous anther fi laments (fig. 4a). carrying obovate, reticulate leaves, the sparse material from ny-ålesund is also referable to salix lanata. both populations resemble low-growing strains of ssp. richardsonii (hook.) a. skvortzov, a view advanced by elven (pers. comm. 2002). further investigation is needed to assess the local distribution and phytogeographical connections of salix lanata in spitsbergen. vaccinium uliginosum the species was discovered in 1908 at mimerdalen (lid 1925) and subsequently collected at what was then known as coles bay by g. holmsen in 1912. the vaccinium habitat at kreklingpasset, north of adventdalen, approximately 200 m asl, was exposed to natural erosion in 1981 (j. nilsen, pers. comm. 1999). the species was not seen there in 1998 and may have been locally extirpated. the colesdalen population is medium-sized, covering more than half of an area of 1360 m2 (consisting of one genotype), with two satellites (a closely related genotype) extending over 3.2 m2 and 16 m2, located 32 m and 40 m uphill, respectively (alsos, brochman et al. 2002). the colesdalen habitat is a south-facing slope with prostrate vaccinium mixed with cassiope tetragona and dryas octopetala. at rusanovodden, 40 m asl, another medium-sized population, not fl owering, was discovered in 2002. it occurred with betula nana and empetrum nigrum ssp. hermaphroditum (alsos, lund et al. 2002). no germinable seeds or seed bank have been found in the colesdalen population, the only place where fl owers or fruits have been observed in svalbard (alsos et al. 2003; cooper et al. in press). one vaccinium stand at mimerdalen extending over a few square metres, probably on the hill estheriahaugen (o. a. høeg, 1928, trh), was accompanied by dryas octopetala, carex rupestris, bistorta vivipara, luzula arcuata ssp. confusa, salix polaris, dicranum laevidens, tomentypnum nitens and several fruticose lichens, e.g. thamnolia vermicularis (möller & thannheiser 1997). idodalen harbours stands of two partly overlapping v. uliginosum genotypes measuring 120 m2 and 60 m2, only 3 m apart (alsos, brochman et al. 2002). co-dominant were cassiope tetragona, saxifraga oppositifolia and tomentypnum nitens associating with some restricted, calciphilous species, e.g. tofi eldia pusilla. material from colesbukta was found to be di ploid with 2n = 24 (flovik 1940). all the svalbard populations are referred to the circumpolar ssp. microphyllum (lge.) tolm. (alsos et al. 2003). see the distribution map in elvebakk (fig. 32 in 1989). see local map in alsos, lund et al. (2002.) discussion the spitsbergen ranges of the thermophilous species broadly coincide with the inner arctic fjord zone (elvebakk 1989), where the longyearbyen meteorological station enjoys the highest summer warmth, 365 degree-days for july–august. however, we consider this local climate as marginal for the following 12 target species which require more than 400 degree-days for july–august (data from engelskjøn 1994): alchemilla glomerulans, betula nana, calamagrostis stricta, campanula rotundifolia, euphrasia frigida, hippuris vulgaris, juncus castaneus, j. triglumis, ranunculus lapponicus, rubus chamaemorus, salix lanata and vaccinium uliginosum. lack of viable seeds or seed bank in three of these species, i.e. b. nana, c. rotundifolia and v. uliginosum, suggests that thermal requirements for seed production have not been met during recent decades (misund 1997; alsos et al. 2003). among the 20 thermophilous species treated here, 13 attain their northernmost limits in svalbard. the remaining seven have their polar limits 330 twenty thermophilous vascular plant species in svalbard in northern greenland, from 81° 55' to 83° n (fredskild 1966; bay 1992, 1997). a farthest north station of “empetrum nigrum” (edlund & alt 1989) indicates that ellesmere island also possesses world northern limits of fl ora. other boreal or arctic species have been recorded in the fossil or subfossil state north of their present ranges. instances are angelica cf. archangelica (bjørnøya, wohlfahrt et al. 1995); armeria scabra (edgeøya, bennike & hedenäs 1995); parnassia palustris (spitsbergen, van der knaap 1988); saussurea alpina (spitsbergen, van der knaap 1988) and selaginella selaginoides (jan mayen, van der knaap 1987). possible relict occurrences of these or other warmth-demanding species should be searched for in the inner arctic fjord zone of svalbard. eutrophic, mesotrophic and oligotrophic species are represented in the group of thermophilous species. there is no over-representation of species with particular edaphical demands (see elvebakk 1982). the following three species have most populations: calamagrostis stricta (108), empetrum nigrum ssp. hermaphroditum (approximately 80), and ranunculus lapponicus (70). in these cases, medium-sized or large populations prevail and the species may be locally copious. accordingly, they were rated as at lower risk in svalbard. less frequent, with 22 to 39 populations, are betula nana, hippuris vulgaris (found only on bjørnøya), juncus triglumis, rhodiola rosea (mainly on bjørnøya) and ranunculus arcticus. they are rated as vulnerable or at lower risk. species with 1 16 populations are alchemilla glomerulans (only on bjørnøya), campanula rotundifolia, carex marina ssp. pseudolagopina, euphrasia frigida, juncus castaneus, kobresia sim pliciuscula, luzula wahlenbergii, ranunculus pallasii, r. wilanderi, rubus chamaemorus, salix lanata and vaccinium uliginosum. depending on local conditions, they are rated as vulnerable, endangered or critically endangered. the latter category—critically endangered at the regional level—comprises alchemilla glomerulans (confi ned to bjørnøya), ranunculus wilanderi (confi ned to kapp thordsen), salix lanata (extirpated at ny-ålesund, persisting at adventdalen) and vaccinium uliginosum (critically endangered at colesdalen because of a mining scheme). among the target species, betula nana, campanula rotundifolia and salix lanata are entirely unprotected by the present area-based conservation plan (fig. 2). one svalbard population of salix lanata has probably become extirpated, the remaining one, consisting of only male plants, is threatened by natural erosion. ex situ conservation is now being implemented at the phytotron of the university of tromsø and tromsø botanic gardens. there are strong norwegian and russian mining interests within several of the proposed nature reserves in svalbard. as a result, the norwegian conservation authorities have signalled that mining and conservation interests should be combined to some extent within the protected areas (miljøverndepartementet 2003). the proposed protected area at colesdalen (governor of svalbard 1999; alsos, lund et al. 2002) has been disputed due to russian mining interests and has so far not been protected by the norwegian government (miljøverndepartementet 2003), contrary to botanical recommendations. this area includes populations of betula nana, campanula rotundifolia, empetrum nigrum ssp. hermaphroditum, euphrasia frigida, ranunculus lapponicus and vaccinium uliginosum. the climate-correlated, northward decline of vascular plant species (murray 1997) shows a local anomaly in the inner arctic fjord zone of spitsbergen, especially in dickson land, sabine land and nordenskiöld land, which altogether harbour more than 15 thermophilous species (fig. 3). due to its small and fragmented populations, this phytogeographical element needs further investigation as to its holocene past. it is clearly in need of conservation. acknowledgements.—we thank liv borgen, arne pedersen, hans-joachim schweitzer and associates for participating in fi eldwork in 1967, 1970 or both; sigbjørn dunfjeld and ola skifte in 1983; christian brochmann, arve elvebakk, reidar elven, lars hodin and sigmund spjelkavik in 1985; jan thomas schwenke, sigmund spjelkavik and anne steilnes in 1986; knut engelskjøn and anne steilnes in 1987; mari aasen in 1998, bjørn erik sandbakk in 1998, 1999, 2002 and 2003, members of the north norwegian botanical association in 2002 and kjell tore hansen in 2003. geir mathiassen provided notes on betula nana and mushrooms at adventdalen in 1986; information on juncus castaneus was provided by may-britt eriksen norberg; on luzula wahlenbergii by birgit brosø, on rubus chamaemorus by ivar hauge and jarle nilsen and on vaccinium uliginosum by jarle nilsen. we thank george argus, merrickville, ontario, and reidar elven, oslo, for comments on the adventdalen salix lanata, and arve elvebakk for providing an in situ photograph of the presently extirpated s. lanata at ny-ålesund. we are indebt331engelskjøn et al. 2003: polar research 22(2), 317–339 ed to ernst høgtun for preparing the maps. the present study was fi nanced by tromsø museum, the norwegian polar institute, the norwegian national committee for polar research (7/221.34-10/98) and the roald amundsen centre for arctic research (a 21/98). arve elvebakk shared some unpublished plant fi nds and provided valuable comments on the manuscript, as did torbjørn alm. elisabeth cooper reviewed the language. we thank the anonymous reviewers for constructive suggestions. references alsos, i. g. 2000: utbredelse av sjeldne karplanter sett i forhold til “plan for nye verneområder på svalbard”. (distribution of rare vascular plants in relation to the “plan for new protected areas in svalbard.”) polarfl okken 23, 193– 201. alsos, i. g. 2003: conservation biology of the most thermophilous plant species in the arctic. genetic variation, recruitment and phytogeography in a changing climate. dr. scient. thesis, university of tromsø. alsos, i. g., brochmann, c. & engelskjøn, t. 2002: conservation genetics and population history of betula nana, vaccinium uliginosum, and campanula rotundifolia in the arctic archipelago of svalbard. arct. antarct. alp. res. 34, 408–418. alsos, i. g. & lund, l. 1999: fjelløyentrøst euphrasia frigida funnet i colesdalen, svalbard. (euphrasia frigida found in colesdalen, svalbard.) blyttia 57, 36. alsos, i. g., lund, l., sandbakk, b. e. & westergaard, k. 2002: floraen i colesdalen. kartlegging av det planlagte verneområde. (the fl ora of colesdalen. mapping of the planned protected area.) tromsø: botany unit, tromsø museum, university of tromsø. alsos, i. g., spjelkavik, s. & engelskjøn, t. 2003: seed bank size and composition of betula nana, vaccinium uliginosum, and campanula rotundifolia in svalbard and northern norway. can. j. bot. 81, 220–231. andersson, g. 1910: die jetzige und fossile quartär fl ora spitzbergens als zeugnis von klimaänderungen. (the present and fossil quaternary fl ora of spitsbergen as evidence for climatic change.) in: ii. internationaler geologenkongress. die veränderungen des klimas seit dem maximum der letzten eiszeit. pp. 409–417. stockholm: generalstabens litografi ska anstalt. andersson, g. & hesselman, h. 1900: bidrag till kännedomen om spetsbergens och beeren eilands kärlväxtfl ora grundade på iakttagelser under 1898 års svenska polarexpedition. (contribution to the vascular fl ora of spitsbergen and bjørnøya based on observations during the swedish polar expedition 1898.) bihang kungliga svenska vetenskaps-akademiens handlingar 26, iii, 1–88. asplund, e. 1919: beiträge zur kenntnis der fl ora des eisfjordgebietes. (contribution to the fl ora of the isfjorden area.) ark. bot. 15, 1–40. aune, b. 1993: temperaturnormaler, normalperiode 1961– 1990. (temperature normals, normal period 1961–1990.) klima 93. oslo: norwegian meteorological institute. baranowski, s. 1975: the climate of west spitsbergen in the light of material obtained from isfjord radio and hornsund. acta univ. wratislav. 251, 21–34. bay, c. 1992: a phytogeographical study of vascular plants of northern greenland—north of 74° northern latitude. medd. grønl. biosci. 36. bay, c. 1997: floristic and ecological characterization of the polar desert zone of greenland. j. veg. sci. 8, 685–696. bennike, o. & hedenäs, l. 1995: early holocene land fl oras and faunas from edgeøya, eastern svalbard. polar res. 14, 205–214. birks, h. h. 1991: holocene vegetational history and climatic changes in west spitsbergen—plant macrofossils from skardtjørna, an arctic lake. the holocene 1, 209–218. böcher, t. w. 1952: a study of the circumpolar carex heleonastes–amblyorhyncha complex. acta arct. 5, 1–32. böcher, t. w. 1960: experimental and cytological studies on plant species v. the campanula rotundifolia complex. biol. skr. dan. vidensk. selsk. 11, 1–69. böcher, t. w., holmen, k., fredskild, b. & jakobsen, k. 1978: grønlands fl ora. 3. reviderede udgave. (the fl ora of greenland. 3rd revised edition.) copenhagen: p. haase & søn. borissova, a. g. 1939: crassulaceae dc. flora sssr 9, 8– 134, 471–486. cooper, e. j., alsos, i. g., hagen, d., smith, f. m., coulson, s. & hodkinson, i. in press: plant recruitment in the high arctic: seed bank and seedling emergence in the fi eld on svalbard. j. veg. sci. croff, b. e. 1978: campanula rotundifoliakomplekset i norge. en cytologisk og morfologisk analyse. (the campanula rotundifolia complex in norway. a cytological and morphological analysis.) cand. real. thesis, university of oslo. dahl, e. 1937: on the vascular plants of eastern svalbard. skrifter om svalbard og ishavet 75. oslo: norway’s svalbard and arctic ocean research survey (predecessor of the norwegian polar institute). dahl, e. & hadač, e. 1946: et bidrag til spitsbergens fl ora. (a contribution to the fl ora of spitsbergen.) meddelelser 63. oslo: norway’s svalbard and arctic ocean research survey (predecessor of the norwegian polar institute). dahl, o. 1934: floraen i finnmark fylke. (the fl ora of finnmark county.) nyt magazin for naturvidenskaberne 169. de groot, w. j., thomas, p. a. & wein, r. w. 1997: betula nana l. and betula glandulosa michx. j. ecol. 85, 241– 264. dubiel, e. 1990: vascular plants of the nw part of sørkapp land (spitsbergen). distribution and habitats. zesz. nauk. univ. jagiell. prace bot. 21, 7–33. edlund, s. a. & alt, b. t. 1989: regional congruence of vegetation and summer climate patterns in the queen elizabeth islands, northwest territories, canada. arctic 42, 3–23. elvebakk, a. 1982: geological preferences among svalbard plants. inter-nord 16, 11–31. elvebakk, a. 1985: higher phytosociological syntaxa on svalbard and their use in subdivision of the arctic. nordic j. bot. 5, 273–284. elvebakk, a. 1989: biogeographical zones of svalbard and adjacent areas based on botanical criteria. dr. scient. thesis, university of tromsø. elvebakk, a. 1993: myrtust (kobresia simpliciuscula) på sval bard. (kobresia simpliciuscula in svalbard.) polarfl okken 17, 249–254. elvebakk, a., elven, r., spjelkavik, s., thannheiser, d. & schweitzer, h.-j. 1994. botrychium boreale and puccinellia angustata ssp. palibinii new to svalbard. polarfl okken 18, 133–140. elvebakk, a., engelskjøn, t. & hodin, l. 1987: vegetasjons332 twenty thermophilous vascular plant species in svalbard skader i berzeliusdalen. (vegetation damage at ber zel iusdalen.) in p. prestrud & n. a. øritsland (eds.): miljø undersøkelser i tilknytning til seismisk virksomhet på svalbard 1986. nor. polarinst. rapp.ser. 34, 161–194. elvebakk, a. & hertel, h. 1996: lichens. in a. elvebakk & p. prestrud (eds.): a catalogue of svalbard plants, fungi, algae, and cyanobacteria. nor. polarinst. skr. 198, 271– 359. elvebakk, a. & spjelkavik, s. 1981: botanisering blant varme kjelder og vulkanar på nord-svalbard. (botanizing among hot springs and volcanos in northern svalbard.) polarfl okken 5, 104–113. elvebakk, a. & spjelkavik, s. 1995: the ecology and distribution of empetrum nigrum ssp. hermaphroditum on svalbard and jan mayen. nord. j. bot. 15, 541–552. elven, r. 1994 (ed.): johannes lid, dagny tande lid: norsk fl ora. (johannes lid, dagny tande lid: norwegian fl ora.) oslo: det norske samlaget. elven, r. & elvebakk, a. 1996: vascular plants. in a. elvebakk & p. prestrud (eds.): a catalogue of svalbard plants, fungi, algae, and cyanobacteria. nor. polarinst. skr. 198, 9–55. elven, r. & elvebakk, a. 2002: sibirstarr carex bige lowii ssp. arctisibirica på svalbard og noe om stivstarr–komplekset c. bigelowii coll. (carex bigelowii ssp. arctisibirica in svalbard and comments on the c. bigelowii complex.) blyttia 60, 50–58. elven, r., eriksen, m.-b., elvebakk, a., johansen, b. & engelskjøn, t. 1990: gipsdalen, central svalbard; fl ora, veg etation and botanical values. in b. brekke & r. hanson (eds.): environmental atlas, gipsdalen, svalbard. ii. nor. polarinst. rapp.ser. 61, 27–66. elven, r. & karlsson, t. 2000: salicaceae: salix arctica pall. in b. jonsell (ed.): flora nordica 1. lycopodiaceae—polypodiaceae. pp. 141–142. stockholm: bergius foundation. engelskjøn, t. 1979: chromosome numbers in vascular plants from norway, including svalbard. opera bot. 52, 1–38. engelskjøn, t. 1986: zonality of climate and plant distribution in some arctic and antarctic regions. nor. polarinst. rapp.ser. 30. engelskjøn, t. 1987: eco-geographical relations of the bjørnøya vascular fl ora, svalbard. polar res. 5, 79–127. engelskjøn, t. 1994: highand mid-alpine vegetation in north scandinavia. ecology and thermal relations. tromura, naturvitenskap 74. tromsø: tromsø museum, univesrity of tromsø. engelskjøn, t., kramer, k. & schweitzer, h.-j. 1972: zur fl ora des van mijenfjordengebietes und hopens. (contribution to the fl ora of the van mijenfjorden district and hopen.) nor. polarinst. årb. 1970, 191–198. engelskjøn, t. & schweitzer, h.-j. 1970: studies on the fl ora of bear island (bjørnøya). i. vascular plants. astarte 3, 1– 36. engelskjøn, t. & spjelkavik, s. 1999: vegetasjon med dvergbjørk (betula nana l.) ved colesdalen, svalbard. (vegetation supporting dwarf birch (betula nana l.) at colesdalen, svalbard.) polarfl okken 23, 21–28. ericsson, s. 2001: ranunculaceae: ranunculus auricomus. in b. jonsell (ed.): flora nordica 2. chenopodiaceae—fumariaceae. pp. 237–255. stockholm: bergius foundation. fagerström, l. & kvist, g. 1983: vier neue arktische und subarktische ranunculus auricomus-sippen. ann. bot. fenn. 20, 237–243. flovik, k. 1940: chromosome numbers and polyploidy within the fl ora of spitzbergen. hereditas 26, 430–440. fredskild, b. 1966: contribution to the fl ora of peary land, north greenland. medd. grønl. 178(2). fredskild, b. 1998: the vegetation types of northeast greenland. medd. grønl. biosci. 49. fries, t. m. 1869: tillägg till spetsbergens fanerogam-fl ora. (addition to the phanerogamic fl ora of spitsbergen.) öfversigt kungliga vetenskaps-akademiens förhandlingar 26, 121–144. frisvoll, a. a. & elvebakk, a. 1996: bryophytes. in a. elvebakk & p. prestrud (eds.): a catalogue of svalbard plants, fungi, algae, and cyanobacteria. nor. polarinst. skr. 198, 57–172. gadella, w. 1964: cytotaxonomical studies in the genus campanula. wentia 11. governor of svalbard 1999: melding om konsekvensutredning. plan for nye verneområder på svalbard. (consequence assessment report. plan for new protected areas in svalbard.) longyearbyen: offi ce of the governor of svalbard. gulden, g. & torkelsen, a. e. 1996: fungi i. basidiomy cota: agaricales, gasteromycetales, aphyllophorales, exobasidiales, dacrymycetales and tremellales. in a. elvebakk & p. prestrud (eds.): a catalogue of svalbard plants, fungi, algae, and cyanobacteria. nor. polarinst. skr. 198, 173– 206. hadač, e. 1944: die gefässpfl anzen des “sassengebietes” vestspitsbergen. (the vascular plants of the “sassen quarter”, west spitsbergen.) skrifter om svalbard og ishavet 87. oslo: norway’s svalbard and arctic ocean research survey (predecessor of the norwegian polar institute). halliday, g. & chater, a. o. 1969: carex marina dewey, an earlier name for c. amblyorhyncha krecz. feddes repert. 80, 103–106. hansen, j. r., hansson, r. & norris, s. 1996: the state of the european arctic environment. environmental monograph 3. oslo: european environment agency. hjelmstad, r. 1981: floraog vegetasjonsundersøkelser på barentsøya. (investigations of fl ora and vegetation on barentsøya.) mab i norge—svalbardprosjektet. rapp. 8. oslo. hofmann, w. & thannheiser, d. 1972: floristische neufunde von krossund kongsfjord, spitzbergen. (new fl oristic discoveries at krossfjord and kongsfjord, spitsbergen.) polarforschung 42, 122–124. högbom, b. 1913: om spetsbergens mytilustid. (on the mytilus epoch of spitsbergen.) geol. fören. för handl. 35, 151–155. holmboe, j. 1910: moden krækling fra spitsbergen. (ripe empetrum from spitsbergen.) naturen 34, 380–381. holmen, k. 1957: the vascular plants of peary land, north greenland. medd. grønl. 124. holmgren, p. k., holmgren, n. h. & barnett, l. c. 1990: index herbariorum. part i: the herbaria of the world. new york: new york botanical garden. hultén, e. 1958: the amphi-atlantic plants and their phytogeographical connections. kungliga svenska vetenskapsakademiens handlingar. ser. 4(7). hultén, e. 1964: salix glauca subsp. callicarpaea in spitsbergen. sven. bot. tidskr. 58, 350. hultén, e. 1968: flora of alaska and neighboring territories. stanford: stanford university press. hultén, e. 1973: supplement to fl ora of alaska and neighboring territories. a study in the fl ora of alaska and the transberingian connection. bot. not. 126, 459–512. hultén, e. & fries, m. 1986: atlas of north european vascular plants north of the tropic of cancer. königstein: koeltz 333engelskjøn et al. 2003: polar research 22(2), 317–339 scientifi c books. iucn (world conservation union) 2001: iucn red list categories and criteria version 3.1. on the internet at www. redlist.org/info/categories_criteria.html. jørgensen, c. a., sørensen, t. & westergaard, m. 1958: the fl owering plants of greenland. a taxonomical and cytological study. biologiske skrifter kongelige danske videnskabers selskab 9. keilhau, b. m. 1831: reise i östog vest-finmarken samt til beeren-eiland i aarene 1827 og 1828. (travel to eastern and western finnmark and to bjørnøya during the years 1827 and 1828.) christiania (oslo): cappelen. kuc, m. & dubiel, e. 1995: the vascular plants of the hornsund area (sw spitsbergen). fragm. flor. geobot. 40, 797–824. laane, m. m. 1968: cyto-ecological studies in norwegian cam panula-species. bot. tidsskr. 63, 319–334. lid, j. 1925: four new phanerogams from svalbard (spits bergen). nyt magazin for naturvidenskaberne 63, 315–316. lid, j. 1962: stutt-arve funnen på svalbard. (sagina caespitosa found in svalbard.) blyttia 20, 100–101. lid, j. 1964: the fl ora of jan mayen. nor. polarinst. skr. 130. lid, j. 1967: synedria of twenty vascular plants from svalbard . bot. jahrb. 86, 481–493. lynge, b. 1924: vascular plants from novaya zemlya. report of the scientifi c results of the norwegian expedition to novaya zemlya 1921. no. 13. kristiania (oslo): videnskapsselskapet. major, h. & nagy, j. 1966: geology of the adventdalen area. with geological map, svalbard c9g, 1:100 000. nor. polarinst. skr. 138. malmgren, a. j. 1862: öfversigt af spetsbergens fanerogamfl ora. (survey of the phanerogamic fl ora of spitsbergen.) öfversigt kungliga vetenskaps-akademiens förhandlingar 1862, 229–268. michelmore, a. p. g. 1934: botany of the cambridge expedition to edge island, s.e. spitsbergen, in 1927. j. ecol. 22, 156–176. miljøverndepartementet 2003: mest omfattende vern på 30 år sikrer svalbards unike natur. (the most comprehensive protection in 30 years safeguards the unique nature of svalbard.) press release 26/09/03. oslo: ministry of the environment. available on the internet at http://odin.dep.no/ md /norsk /tema /svalba rd /a rk iv/ 022021070159/i ndexdok000-b-n-a.html. misund, s. 1997: germination and growth in betula nana l. from spitsbergen and tromsø. cand. scient. thesis, university of tromsø. möller, i. 2000: pfl anzensoziologische und vegetationsökologische studien in nordwestspitzbergen. (phytosociological and vegetation ecological studies in northwestern spitsbergen.) mitt. geogr. ges. hamb. 90. möller, i. & thannheiser, d. 1997: eine v\vegetationsoase im unteren mimerdalen am billefjord, zentral-spitzbergen. (a vegetational oasis at lower mimerdalen, billefjord, central spitsbergen.) polarforschung 65, 65–70. murray, d. f. 1997: regional and local vascular plant diversity in the arctic. opera bot. 132, 9–18. nathorst, a. g. 1871: om vegetationen på spetsbergens vest kust. (on the vegetation on the western coast of spitsbergen.) bot. not. 1871, 105–117. nathorst, a. g. 1883: nya bidrag till kännedomen om spetsbergens kärlväxter, och dess växtgeografi ska förhållanden. (new contributions to the knowledge of the vascular plants of spitsbergen, and their phytogeographical relations.) kungliga svenska vetenskaps-akademiens handlingar 20. neilson, a. h. 1968: vascular plants from the northern part of nordaustlandet, svalbard. nor. polarinst. skr. 143. neilson, a. h. 1970: vascular plants of edgeøya, svalbard. nor. polarinst. skr. 150. resvoll-holmsen, h. 1913: observations botaniques. exploration de nord-ouest de spitsberg entreprise sous les auspices de s.a. le prince de monaco par la mission isachsen. (botanical observations. exploration of northwestern spitsbergen performed by the isachsen expedition, sponsored by h. e. the prince of monaco.) résultats campagne scientifi que prince albert i, 44. imprimerie de monaco. rønning, o. i. 1961: some new contributions to the fl ora of svalbard. norsk polarinst. skr. 124. rønning, o. i. 1972: the distribution of the vascular cryptogams and monocotyledons in svalbard. det kongelige norske videnskabers selskabs skrifter 24. rønning, o. i. 1996: svalbards fl ora. (flora of svalbard.) polarhåndbok 9. oslo: norwegian polar institute. rudmose brown, r. n. 1908: the fl ora of prince charles foreland, spitsbergen. bot. soc. edinb. trans. 23, 313–320. schweitzer, h.-j. 1966: beiträge zur flora svalbards. (contributions to the fl ora of svalbard.) nor. polarinst. årb. 1964, 139–148. shetler, s. g. 1982: variation and evolution of the nearctic hare bells (campanula subsect. heterophylla). phanerogamarum monographiae 11. vaduz, liechtenstein: j. cramer. simmons, h. g. 1906: the vascular plants in the fl ora of ellesmereland. results of the norwegian arctic expeditions in the “fram” 1898–1902, 2. kristiania (oslo): videnskabs-selskapet. sørensen, t. 1933: the vascular plants of east greenland from 71°00' to 73°30' n. lat. medd. grønl. 101. spjelkavik, s. 1991: vegetasjonsundersøkelser langs foreslåtte veitraséer mellom longyearbyen og svea. investigation of vegetation along proposed roads between longyearbyen and svea. nor. polarinst. medd. 117, 11–26. steffensen, e. 1982: the climate at norwegian arctic stations. klima 5. oslo: norwegian meteorological institute. stortinget 2000: reg jeringens miljøvernpolitikk og rikets miljøtilstand. stortingsmelding nr. 8, 1999–2000. (environmental policies of the government and the environmental state of the kingdom.) oslo: ministry of the environment. available on the internet at http://odin.dep.no/ md/norsk/publ/stmeld/022005-040006/index-dok000-bn-a.html. summerhayes, v. s. & elton, c. s. 1928: further contributions to the ecology of spitsbergen. j. ecol. 16, 193–268. sunding, p. 1966: plantefunn fra vestspitsbergen sommeren 1964. (plant fi nds on spitsbergen, the summer of 1964.) nor. polarinst. årb. 1964, 149–154. thannheiser, d. 1972: vegetationskartierungen auf der germaniahalvøya. vegetation mapping on the germaniahalvøya. stuttg. geogr. stud. 117, 141–160. theisen, f. & brude, o. w. 1998: evaluering av områdevernet på svalbard. representativitet og behov for ytterligere vern. (assessment of the areal protection in svalbard. representativity and needs of extended protection.) nor. polarinst. medd. 153. tolmachev, a. i. 1976: flora severo-vostoka evropeiskoi časti sssr ii. cyperaceae–caryophyllaceae. (flora of the north-western european parts of the ussr ii. cyperace334 twenty thermophilous vascular plant species in svalbard ae–caryophyllaceae.) leningrad: nauka. tolmachev, a. i., packer, j. g. & griffi ths, g. c. d. (eds.) 1996: the fl ora of the russian arctic 3: salicaceae to ranunculaceae. edmonton: university of alberta press. triloff, e. g. 1944: verbreitung und ökologie der gefässpfl anzen im gebiete des hornsundes: ein beitrag zur vegetationskunde spitzbergens. (distribution and ecology of the vascular plants of the hornsund area: a contribution to the knowledge of the vegetation of spitsbergen.) bot. jahrb. 37, 259–360. turnbull, r. 1900: contributions to the fl ora of spitsbergen, especially of red bay, from the collections of w. s. bruce, f.r.s.g.s., naturalist to the prince of monaco’s expeditions of 1898 and 1899. transactions and proceedings of the botanical society of edinburgh 1900, 352–357. van der knaap, w. o. 1987: five short pollen diagrams of soils from jan mayen, norway: a testimony of a dynamic landscape. polar res. 5, 193–206. van der knaap, w. o. 1988: a pollen diagram from brøggerhalvøya, spitsbergen: changes in vegetation and environment from ca. 4400 to ca. 800 bp. arct. alp. res. 20, 106– 116. van der knaap, w. o. 1989: past vegetation and reindeer on edgeøya (spitsbergen) between c. 7900 and c. 3000 bp, studied by means of peat layers and reindeer faecal pellets. j. biogeogr. 16, 379–394. wirén, e. 1922: iakttagelser under några botaniska exkursioner på spetsbergen. (observations during some botanical excursions on spitsbergen.) sven. bot. tidskr. 16, 363– 370. wohlfahrt, b., lemdahl, g., olsson, s., persson, t., snowball, i., ising, j. & jones, v. 1995: early holocene environment on bjørnøya (svalbard) inferred from multidisciplinary lake sediment studies. polar res. 14, 253–275. species population sizes part of svalbard location source, herbaria with voucher specimens l m s nd ∑ alchemilla glomerulans bjørnøya se of herwighamna te 1983, trom; te (1987) 1 1 total 1 1 betula nana nordenskiöld land rusanovodden towards colesbukta nathorst 1882, o; ia & ll 1998; ia, ll et al. (2002) 1 1 2 colesbukta, w, s sides strandwitz 1930, trom; te & ss (1999) 1 2 5 1 9 colesbukta, e, n sides fries (1869); te & ss 1986; trom; ia, te, ll, bs & ma 1998; ia & bs 1999 1 2 3 colesdalen, n side te & ss 1986, trom; ia & ll 1998; ia & bs 1999, ia, ll et al. (2002) 1 3 3 7 colesdalen, interior te & ss 1986, trom 1 1 fardalen ll 1997 1 1 2 grønfjorddalen ae (1990) 1 1 hotellneset vogt 1928, o 1 1 endalen os 1988, trom; ia, te, ll, bs & ma 1998 1 1 todalen te & ap 1970, trom 1 1 janssonhaugen te 1970, trom 1 1 adventdalen, n side högbom (1913); hadač (1944); sunding (1966); lid (1967); te & ss 1986, trom; ia & ll 1998 1 3 6 10 total 5 13 18 3 39 appendix 1 the table below lists the locations and population sizes of 20 thermophilous vascular plant species in svalbard. localities within established protected areas (fig. 2) are in boldface. names of fi eldworkers are abbreviated as follows: inger greve alsos–ia; mari aasen–ma; geir arnesen– ga; liv borgen–lb; christian brochmann– cb; torstein engelskjøn–te; arve elvebakk– ae; reidar elven–re; ivar hauge–ih; kjell tor hansen–kh; leidulf lund–ll; arne pedersen– ap; olaf i. rønning–or; hanna resvoll-dieset/ resvoll-holmsen–hr; sigmund spjelkavik–ss; bjørn erik sandbakk–bs; hans-joachim schweitzer–hs; jan thomas schwenke–js; ola skifte–os; kristine westergaard–kw. years following fi eldworkers’ names indicate when plant populations were located. names followed by years in parentheses refer to sources in the reference list. see table 5 for abbreviations of herbaria. population sizes (see table 1) are large–l; medium–m; small–s. nd stands for no data and ∑ is sum. 335engelskjøn et al. 2003: polar research 22(2), 317–339 calamagrostis stricta bjørnøya dispersed on plain te (1987) 10 9 7 26 sørkapp land hornsund, s side dubiel 1985, trom 1 1 wedel jarlsberg land hornsund, n side triloff (1944) 2 2 recherchefjorden dunderbukta or & os 1960, trom 2 2 nathorst land midterhuken te et al. (1972) 1 1 akseløya te et al. (1972) 1 1 nordenskiöld land bellsund, berzeliusdalen dahl & hadač (1946); te & ap 1970; te & js 1987, trom 1 2 3 6 reindalen te & ap 1970; cb & te 1985; te & ss 1986, trom 3 4 7 de geerdalen hadač (1944); te 1970 1 5 6 adventfjorden, adventdalen, tributaries hadač (1944); te & ap 1970; te & ss 1986; te 1995, 1996, trom 10 5 1 10 26 bjørndalen asplund (1919); ia, bs 2003, o 1 1 colesbukta, colesdalen te & ss 1986, trom; ia, ll et al. (2002) 1 8 3 1 13 russekeila, kapp linné dahl & hadač (1946) 2 2 sabine land sassendalen, n side re & js 1986, trom 1 1 bünsow land bjonadalen asplund (1919) 1 1 dickson land kapp thordsen dahl & hadač (1946) 2 2 hugindalen lid (1967) 1 1 oxaasfjellet rønning (1972) 1 1 james i land kapp wærn nathorst (1883) 1 1 oscar ii land bohemanneset lid 1924; hadač 1939, o 1 1 haakon vii land blomstrandhalvøya or & os 1958, trom 1 1 kongsfjorden, e side ae (1989); ia 1993 1 2 3 liefdefjorden, s, w ae (1989); möller (2000) 2 2 total 12 33 21 43 108 campanula rotundifolia nordenskiöld land colesdalen, ne side asplund 1915, o, asplund (1919); ia, te, ll, ma & bs 1998, 1999, trom 1 1 colesdalen, n side te & ss 1986; ll 1997; ia, ll & bs 1998, trom; ia & bs 1999; ia, ll et al. (2002) 1 1 2 colesbukta towards rusanovodden ia, ll et al. (2002) 1 1 total 1 3 4 carex marina ssp. pseudolagopina nordenskiöld land sassendalen, s side ae & eriksen 1988 , trom 1 1 sabine land sassendalen, n side nathorst 1882, c; hs (1966); re et al. 1986–89, o, trom 6 6 bünsow land gipsdalen cb, te, ae & re 1985; eriksen 1987, o, trom 1 1 5 7 dickson land kapp thordsen dahl 1981, pers. comm. 1984 1 1 haakon vii land liefdefjorden thannheiser (1972) 1 1 total 1 1 5 9 16 empetrum nigrum ssp. hermaphroditum wedel jarlsberg land recherchefjorden lynge 1926, o 1 1 observatoriefjellet elvebakk, pers. comm. 2002 1 1 nathorst land van keulenfjorden, annahamna lynge 1926, o 1 1 van keulenfjorden, louisefjellet lid 1920, o 1 1 nordenskiöld land bellsund or & os 1958, trom 2 1 3 berzeliusdalen te, ap & hs 1970, trom 1 1 species population sizes part of svalbard location source, herbaria with voucher specimens l m s nd ∑ 336 twenty thermophilous vascular plant species in svalbard van mijenfjorden, n, w, camp morton area, 30 40 m asl holmboe (1910); ae & hodin 1986, trom 3 3 reindalen, tributaries te et al. (1972); cb, te 1985, trom; ss (1991) 1 3 3 1 8 lundströmdalen ss (1991) 1 1 van mijenfjorden, n te et al. (1972) 1 1 grønfjorden area fries (1869), asplund (1919), wirén (1922) 1 1 hollendardalen sunding (1966) 1 1 colesbukta, both sides te & ss 1986, trom; te & ss (1999); ia, te, ll, bs & ma 1998; ia & kw 2002 3 2 2 7 colesdalen, n side te & ss 1986, trom; te & ss (1999), ia & ss 1999; ia, ll et al. (2002) 1 4 5 adventfjorden, adventdalen, tributaries nathorst (1883); hadač (1944); sunding (1966), te & ap 1970; ga & te 1996, trom; ia & ll 1998 4 1 1 6 dickson land mimerdalen and pyramiden nathorst (1883); högbom (1913); möller, thannheiser (1997); ia & ll 1998 1 1 odindalen re 1990, trom 1 1 kapp wijk ballye 1896, cge 1 1 kapp thordsen 75 m asl re 1992, trom 1 1 james i land ekmanfjorden, kapp wærn fries (1869); asplund (1919) 3 3 oscar ii land bohemanneset andersson & hesselman (1900) 1 1 st. jonsfjorden area iversen & koefoed 1923, bg, o 1 1 ymerbukta nathorst (1883) 1 1 bertilfjellet asplund (1919) 1 1 kongsfjorden area hofmann & thannheiser (1972); möller (2000); ae & ss (1995) 4 2 1 1 8 haakon vii land liefdefjorden, lernerøyane thannheiser (1972); ae & ss (1995); möller (2000) 2 ~10 ~12 raudfjorden iversen & koefoed 1923, o 1 1 albert i land smeerenburgfjorden solheim et al. 1936, o 1 1 krossfjorden, w side hjelle 1964, o 1 1 krossfjorden, e side hofmann & thannheiser (1972); ae & s (1995) 2 2 ny-friesland wijdefjorden, e side summerhayes & elton (1928) 1 1 mosselbukta spicer 1964, o 1 1 gustav v land nordaustlandet, depotodden brattbakk (1981, cited in ae & ss 1995) 1 1 total 8 14 30 28 ~80 euphrasia frigida nordenskiöld land colesdalen ia & ll 1998, trom, ia & ll (1999); ia & bs 1999 3 3 colesbukta, e side ia, ll et al. (2002) 2 2 haakon vii land bockfjorden, trollkjeldene os 1960, trom, or (1961) 1 1 ossian sarsfjellet kh, ia, bs 2003, trom 1 1 total 7 7 hippuris vulgaris bjørnøya n side, plain e (1986a) 2 7 6 15 w and sw sides, plain e (1986a) 3 4 7 total 2 10 10 22 juncus castaneus nordenskiöld land longyeardalen lid 1924, o 1 1 de geerdalen hs (1966) 1 1 sabine land sassendalen nathorst (1883) 1 1 species population sizes part of svalbard location source, herbaria with voucher specimens l m s nd ∑ 337engelskjøn et al. 2003: polar research 22(2), 317–339 gjelhallet dahl 1981, o 1 1 bünsow land gipsdalen eriksen 1987, o, trom; re et al. (1990) 1 1 total 1 4 5 juncus triglumis wedel jarlsberg land recherchefjorden turnbull (1900) 1 1 nordenskiöld land sassenfjorden, s side hadač (1944) 1 1 adventdalen hadač (1944); te, ss 1986, trom 2 1 6 9 bjørndalen hr (1913) 1 1 sabine land sassendalen nathorst (1883); re et al. 1986, trom 1 5 6 bünsow land gipsdalen cb, te, ae, re 1985, trom 2 1 1 4 dickson land mimerdalen to dicksonfjorden lid 1924; lid (1925); re 1990, o, trom 1 5 6 haakon vii land ossian sarsfjellet ae 1988, trom 2 2 blomstrandhalvøya ae 1988, trom 1 1 andrée land purpurdalen dahl, hadač (1946) 1 1 ny-friesland austfjordnes spicer 1964, trom 1 1 wijdefjorden, e side ae 2002, pers. comm. 2002 6 6 total 4 5 30 39 kobresia simpliciuscula bünsow land gipsdalen te 1985, trom; te (1986b) 1 1 dickson land mimerdalen isachsen 1925, o; høeg 1928, trh 1 1 adolf bukta ae 2001, pers. comm. 2001 1 1 haakon vii land kongsfjorden ae 1988, trom (1993) 1 1 2 ny-friesland wijdefjorden, e side ae 2002, pers. comm. 2002 3 3 total 1 3 4 8 luzula wahlenbergii nathorst land bromelldalen lynge 1926, o 1 1 nordenskiöld land berzeliusdalen te, ap 1970; te & js 1987, trom 2 2 reindalen, tributaries harper & spicer 1965, o, trom; te et al. (1972) 3 2 5 adventfjorden, bjørndalen, revneset, longyearbyen nathorst (1883); te & hs 1970, trom; spicer 1965, trom; brosø 1996, trom 1 2 2 5 colesdalen te & ss 1986, trom 1 1 total 1 8 5 14 ranunculus arcticus edgeøya western coast neilson (1970) 1 1 sørkapp land sørkapp kristoffersen 1930, trom 1 1 nathorst land midterhuken to bellsund malmgren 1864, o; te et al. (1972) 1 1 2 nordenskiöld land kolfjellet te et al. (1972); ae et al. (1987) 1 1 de geerdalen, outlet hadač (1944) 2 2 sabine land sassendalen, outlet, n re 1986, trom 2 2 bünsow land gipsdalen, tempelfjorden te, cb, ae, re & hodin 1985, trom 1 8 9 dickson land kapp thordsen, surroundings hr 1908, o; re, ae (1996) 4 4 oscar ii land alkhornet hr 1908, o; or, os 1958, trom 1 1 haakon vii land krossfjorden malmgren (1862) 1 1 ossian sarsfjellet ae 1999, trom; ia, kh, bs 2003, trom 1 1 total 3 10 12 25 ranunculus lapponicus nathorst land bromelldalen te et al. 1970, trom; te et al. (1972) 1 1 species population sizes part of svalbard location source, herbaria with voucher specimens l m s nd ∑ 338 twenty thermophilous vascular plant species in svalbard nordenskiöld land van mijenfjorden, n reindalen, gangdalen lynge 1926; harper 1964, o; te et al. (1972); cb & te 1985, trom; ae 1986 1 8 5 14 de geerdalen, e, w sides hadač (1944); te 1970; re 1987, trom 2 6 8 eskerdalen hadač (1944) 1 1 brentskardet hadač (1944) 1 1 revneset to adventdalen, tributaries nathorst 1868, o; hadač (1944); lid (1967); te & ap 1970; te & ss 1986; te 1987, trom 6 1 5 12 bjørndalen sunding 1960, o 1 1 colesbukta, colesdalen rh 1908, o; e & s 1986, trom; ae 1986, ia, ll et al. (2002) 1 2 1 11 15 sabine land sassendalen, n side asplund 1915, o; re & js 1986, trom; ae & øvstedal 1987, trom 4 4 dickson land kapp thordsen, kapp wijk wilander & nathorst 1870, o; foged 1958, trom; re 1990, o, trom 5 4 1 10 oscar ii land bohemanneset wirén (1922); lid 1924, o 1 1 haakon vii land feiringfjell 5 m asl i. brattbakk 1974, trh 1 1 ny-friesland at wijdefjorden nathorst (1883) 1 1 total 2 21 14 33 70 ranunculus pallasii nordenskiöld land stormyra, below høgsnyta te, ap 1970, trom; te et al. (1972) 1 1 reindalssletta te 1985, trom 3 3 adventfjorden, adventdalen lid 1924, o; or 1959, trom; hs (1966) 1 3 4 kapp laila te 1986, trom 1 1 colesdalen, interior te & ss (1999) 1 1 oscar ii land bohemanfl ya lid 1924, o; re, andersen 1997, trom 1 1 total 1 5 2 3 11 ranunculus wilanderi dickson land kapp thordsen jørgensen 1896, o; ga & te 1996 1 1 total 1 1 rhodiola rosea bjørnøya mainly n and e coast te (1987) 2 4 20 2 28 prins karls forland central, south rudmose brown (1908) 1 1 richardlaguna rønning, pers. comm. 1985 1 1 total 2 4 21 3 30 rubus chamaemorus nordenskiöld land rusanovodden nathorst (1883); ia & ll 1998 1 1 se of rusanovodden ia, ll et al. (2002) 1 1 colesdalen, tenndammen asplund 1915, o, asplund (1919); nilsen 1979, trom; ia & ll 1998 1 1 sabine land sassendalen hr (1913) 1 1 dickson land kapp thordsen re, lb 1992, trom; ga, te & re 1996 1 1 2 james i land ekmanfjorden, w side: below ekmanfjellet, hemsil river nathorst (1883); wirén (1922); nilsen 1979, trom; ia & ll 1998 2 2 sveaneset wirén (1922); ih 1998, pers. comm. 1998 1 1 total 4 3 2 9 salix lanata nordenskiöld land adventdalen n, wsw of innerhytta, ca. 70 m asl hs 1963, o, ss; hs 1964, trom; hs (1966); hultén (1964); te & ss 1986; ia & ll 1998, trom; ll 2001 1 1 oscar ii land ny-ålesund, at storvatn, 40 m asl (extirpated 1990–91) aasgaard & or 1974; or 1991, trh; ae 1976, pers. comm. 2002 1 1 species population sizes part of svalbard location source, herbaria with voucher specimens l m s nd ∑ 339engelskjøn et al. 2003: polar research 22(2), 317–339 total 2 2 vaccinium uliginosum nordenskiöld land colesdalen holmsen 1912, o; finnseth 1936, trom; ll 1997 (photo); ia, ll, bs, ma 1998, trom; ia, bs 1999 1 1 colesbukta towards rusanovodden ia; ll et al. (2002) 1 1 kreklingpasset egge 1940, 1941, o; nilsen 1981, trom 1 1 dickson land mimerdalen högbom (1913); høeg 1928, trh; möller & thannheiser (1997) 1 1 idodalen ia & ll 1998, trom 1 1 total 2 3 5 species population sizes part of svalbard location source, herbaria with voucher specimens l m s nd ∑ doi:10.3402/polar.v34.24008 r e s e a r c h / r e v i e w a r t i c l e patterns and trends of macrobenthic abundance, biomass and production in the deep arctic ocean renate degen,1,2 andrey vedenin,3 manuela gusky,1 antje boetius2 & thomas brey1 1 functional ecology, alfred wegener institute helmholtz centre for polar and marine research, am handelshafen 12, de-27570 bremerhaven, germany 2 helmholtz*max planck group for deep sea ecology and technology, alfred wegener institute helmholtz centre for polar and marine research, am handelshafen 12, de-27570 bremerhaven, germany 3 laboratory of ocean bottom fauna, p.p. shirshov institute of oceanology, 36, nahimovski prospect, ru-117997 moscow, russia keywords deep sea; benthos; macroinvertebrate; carbon flux. correspondence renate degen, functional ecology, alfred wegener institute helmholtz centre for polar and marine research, am handelshafen 12, de-27570 bremerhaven, germany. e-mail: renate.degen@hotmail.com abstract little is known about the distribution and dynamics of macrobenthic communities of the deep arctic ocean. the few previous studies report low standing stocks and confirm a gradient with declining biomass from the slopes down to the basins, as commonly reported for deep-sea benthos. in this study, we investigated regional differences of faunal abundance and biomass, and made for the first time ever estimates of deep arctic community production by using a multi-parameter artificial neural network model. the underlying data set combines data from recent field studies with published and unpublished data from the past 20 years, to analyse the influence of water depth, geographical latitude and sea-ice concentration on arctic benthic communities. we were able to confirm the previously described negative relationship of macrofauna standing stock with water depth in the arctic deep sea, while also detecting substantial regional differences. furthermore, abundance, biomass and production decreased significantly with increasing sea-ice extent (towards higher latitudes) down to values b200 ind m �2 ,b65 mg c m �2 and b73 mg c m �2 y �1 , respectively. in contrast, stations under the seasonal ice zone regime showed much higher standing stock and production (up to 2500 mg c m �2 y �1 ), even at depths down to 3700 m. we conclude that particle flux is the key factor structuring benthic communities in the deep arctic ocean as it explains both the low values in the ice-covered arctic basins and the higher values in the seasonal ice zone. to access the supplementary material for this article, please see supplementary files under article tools online. the density and biomass of marine benthic macrofauna generally decreases with increasing water depth, distance from land, and decreasing latitude from polar and temperate towards tropical latitudes (gage & tyler 1991; levin & gooday 2003; wei et al. 2010). the driving force behind this pattern is the decrease in food input, depending on the regionally varying surface production and the assimilation efficiency in the water column (gage & tyler 1991; levin & gooday 2003 and references therein). the low food concentration in the deep sea leads to a higher share of smaller organisms in total community metabolism*thiel’s (1975) size structure hypothesis. this observation has been corroborated by more recent studies that found a decrease in mean body mass (m) or size with increasing water depth (mcclain et al. 2006; rex et al. 2006; wei et al. 2010). besides food availability, substrate characteristics and hydrodynamic processes are also important factors structuring benthic communities polar research 2015. # 2015 r. degen et al. this is an open access article distributed under the terms of the creative commons attribution-noncommercial 4.0 international license (http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://creativecommons.org/licenses/by-nc/4.0/ http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 (rosenberg 1995). deposit-feeding organisms are reported to dominate areas of reduced flow like the abyssal plains, while suspension feeders are prominent in areas with high bottom current flow, as on continental slopes or mid-ocean ridges (gage & tyler 1991; thistle 2003). compared to standing stock, little is known about patterns of benthic secondary production (p) and productivity in the deep sea. the production to biomass (p/b) ratio represents the rate of biomass turnover and is inversely related to life span (benke 2012). a population whose size structure is dominated by small, fast-growing organisms will show a higher p/b ratio than one consisting of older and slower growing adults (gage & tyler 1991). p corresponds to the newly formed biomass per unit of area and time and depicts*contrary to pure measurements of biomass*exactly that quantity of energy that is available as food for the next trophic level (brey 2001). thus p constitutes the quantitative base of energy flow in benthic food webs and is as such an essential variable for ecosystem models. the few existing studies of deepsea benthic p report a negative correlation with water depth and low values of 0.1�0.2 g c m�2 y�1 at depths below 1500 m (gage 1991; brey & gerdes 1998; cusson & bourget 2005). benthic community p/b ratios of 0.49 y �1 (gage 1991) and 0.55 y �1 (brey & gerdes 1998) are reported from 2900 m depth in the rockall trough (north atlantic) and in the weddell sea. while two studies detected a negative correlation of p/b ratios with water depth (brey & clarke 1993; cusson & bourget 2005), no significant correlation was found by brey & gerdes in 1998. all the previously mentioned studies detected a positive relation of p/b with temperature. today, information about arctic deep-sea benthic communities is even scarcer than information about these communities in the deep sea more generally. this is due to the logistical challenges of sampling the remote, seasonally or permanently ice-covered arctic basins. bluhm et al. (2011) found a significant negative correlation of macrobenthic abundance and biomass with water depth and latitude. based on a thorough literature review, they characterized the arctic deep sea as an oligotrophic area with steep gradients in faunal abundance and biomass from the slopes to the basins, but with overall density and biomass comparable to other deep-sea areas. because of permanent ice cover in the central arctic, surface productivity and associated fluxes are low and previous studies detected extremely low abundances: b200 individuals m �2 and biomasses,b0.2 g carbon (c) m �2 (klages et al. 2004; macdonald et al. 2010; bluhm et al. 2011). nevertheless, comparably low values of 100 individuals m �2 and 0.5 g wet biomass m �2 have been reported from deep-sea regions equally characterized by remoteness from land and low surface productivity, namely the central north pacific, the sargasso sea and the porcupine abyssal plain (gage & tyler 1991). the recent substantial decrease in the ice cover of the arctic ocean (arrigo et al. 2008) has fuelled speculation as to the future of its productivity and related changes in community structure and distribution. the shift from an arctic ocean whose centre is the covered with a thick layer of multiyear ice, and surrounded by a seasonal ice zone, to a system with a mostly seasonal ice zone is already happening (notz 2009). arctic marine ecosystems are expected to change accordingly (wassmann et al. 2011). currently, neither the direction nor mode of these ecological developments is understood sufficiently to predict forthcoming changes in arctic marine ecosystem functions, goods and services. one major obstacle is our lack of knowledge regarding the current system state, as quite often there is no reliable baseline information from which change can be identified (wassmann et al. 2011). as the changes in sea-ice cover and surface productivity are ongoing, it is highly important to increase efforts in establishing such baseline information, including the synthesis of previously unpublished data. here, we focus on the arctic deep-sea macrozoobenthos. deepwater benthic communities are believed to be good indicators of change as they are on average more stationary and long-lived compared to pelagic communities and rely nutritionally almost entirely on the organic flux from euphotic layers. hence they reflect changes in surface layer production in their own dynamics (sibuet et al. 1989; gage & tyler 1991). we compiled data on macrozoobenthic communities sampled during expeditions of the rv polarstern between 1990 and 1997 and in 2012 to the deep fram strait and the central arctic (fig. 1, table 1) and estimated benthic p/b and p by applying the empirical artificial neural network model developed by brey (2012). based on this data set, we tested patterns previously reported (i.e., decrease of standing crop with depth and latitude, decrease of m with depth, distribution patterns of feeding types), and investigated additional drivers of macrozoobenthic community patterns. in order to identify the major spatial patterns in the data set, we grouped the sample stations into regional and latitudinal clusters, depth zones and zones of different sea-ice concentration and tested these groups for significant differences in their communities’ abundance, biomass, m, p, p/b and feeding structure. there are a few estimates of total macrobenthic p from deep-sea regions (gage 1991; brey & gerdes 1998) and high latitudes (nilsen et al. 2006; kedra et al. 2013), but none are macrobenthic abundance, biomass and production in the deep arctic ocean r. degen et al. 2 (page number not for citation purpose) citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 available yet from the central arctic deep sea. our first estimates of benthic p in the arctic deep sea can serve as an initial baseline for comparisons on a regional and basin-wide scale to help understand and predict upcoming changes in the arctic ocean. briefly, the main hypotheses tested were: (1) macrobenthic abundance, biomass and p decrease with increasing water depth, latitude and sea-ice coverage; (2) community p/b increases with depth as a consequence of m decreasing with depth; (3) deposit-feeding organisms dominate in the basins, whereas feedings structures are more evenly distributed on the slopes and ridges. methods study area and data set the study area ranges from the seasonally ice-covered eastern fram strait (788n) up to the permanently icecovered central arctic ocean at 908n. in the region of north-western spitsbergen and fram strait, water depths down to 5600 m are reached at its deepest site, the molloy hole (soltwedel et al. 2005). the inflow of warm atlantic water that enters the arctic ocean via the west spitsbergen current keeps the southern stations only seasonally ice-covered. eastward the west spitsbergen fig. 1 sample stations in 1991, 1997 and 2012, with the number of stations shown in parentheses, and median september sea-ice extent in 2013 and the 1981�2011 median sea-ice extent. r. degen et al. macrobenthic abundance, biomass and production in the deep arctic ocean citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 3 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 current splits up into the svalbard branch and the yermak branch, both affecting the sea-ice conditions on the yermak plateau. this shallow, marginal plateau, located between 80 and 828n, north-west of spitsbergen, ranges from 500 to 800 m on the crest down to 3000 m as it merges into the nansen basin (soltwedel et al. 2000). northwards the nansen and amundsen basins adjoin, with average depths of 4000 m and most areas permanently covered with sea ice. the two basins are separated by the gakkel ridge, a slowly spreading ridge system rising up to 1000 m below sea level (jakobsson et al. 2012). the amundsen basin is limited by the lomonosov ridge, which rises 3000 m above the abyssal plains and separates the eurasian and amerasian basins (kristoffersen et al. 2007). the makarov basin, flanking the lomonosov ridge from the opposite side, is the only region from the amerasian part of the arctic included in this study. the western amundsen basin merges into the steep slopes of the morris jesup rise, which reaches up to 1000 m below sea level and then transitions into the greenland slope (jakobsson et al. 2012; for detailed station information see table 2 and supplementary table s1). the data set used for this study (www.doi.pangaea.de/ 10.1594/pangaea.828348; fig. 1) constitutes a compilation of alfred wegener institute’s arctic macrozoobenthos data (panabio, pan-arctic database of benthic biota, in progress) selected using the following criteria: (1) abundance and biomass data available on species level; (2) comparable sampling and sample treatment (comparable sampling device and sample area and sieving of samples with 250 mm or 500 mm sieve sizes) to keep comparison errors to a minimum; and (3) data distributed along a transect from the fram strait (788n) to the central arctic (908n), with a focus on the eurasian basins. the samples were taken during several rv polarstern cruises between 1991 and 2012 (table 1). data from the cruise arkviii/3 in 1991 (fütterer 1992; 47 stations from northern svalbard, yermak plateau, morris jesup rise and arctic ridges and basins) were published by kröncke (1994, 1998) and samples from cruise ark-xxvii/2 (11 stations from the long-time deep-sea observatory hausgarten, herein referred to as a group as nw spitsbergen) by soltwedel 2013. data from ark-xxvii/3 in 2012 (boetius 2013; five stations in nansen basin and seven in amundsen basin) as well as samples from the cruise ark-xiii/2 in 1997 (stein & fahl 1997; 23 stations: yermak plateau, fram strait) are provided here (table 1, fig. 1). sampling procedure usnel-type box corers of 0.25 m 2 surface area (gage & bett 2005) were used for sampling benthic macrofauna on ark-viii/3 (see kröncke 1994, 1998), ark-xiii/2 and ark-xxvii/2. up to seven subsamples of 0.02 m 2 were table 2 number of sample stations, depth range, number of species and major taxonomical groups and the mean, minimum and maximum parameters abundance (individuals m�2), biomass (mg c m�2) and production (mg c m�2 y�1). abundance (ind m�2) biomass (mg c m�2) production (mg c m�2 y�1) region stations depth (m) species major groups mean min max mean min max mean min max nw spitsbergen 12 2340�5420 26 8 552 171 976 60 13 148 70 12 182 fram strait 4 2530�4130 16 7 326 117 792 49 5 98 39 9 69 yermak plateau 19 520�2930 177 12 1053 88 4136 410 5 2009 385 9 2534 nansen basin 15 2950�4050 32 9 110 6 800 321 b1 3026 138 b1 1585 gakkel ridge 5 1790�4430 2 2 10 0 50 2 0 8 2 0 12 amundsen basin 20 3790�4480 36 7 61 0 346 39 0 492 25 0 247 lomonosov ridge 10 1020�3840 27 8 203 75 450 65 25 126 73 42 130 makarov basin 2 4000�4010 4 3 75 50 100 23 10 35 29 8 51 morris jesup rise 5 1070�3820 19 8 410 100 1450 49 3 230 46 4 205 table 1 overview of stations sampled with rv polarstern used for this study. more detailed station information (coordinates, date, water depth) is provided in supplementary table s1. expedition year gear region reference ark-viii/3 1991 giant box corer (0.25 m �2 ) north svalbard, yermak plateau, nansen and amundsen basins, gakkel and lomonosov ridges, morris jesup rise kröncke 1994, 1998 ark-xiii/2 1997 giant box corer (0.25 m �2 ) fram strait. yermack plateau this study ark-xxvii/2 2012 giant box corer (0.25 m�2) fram strait / nw spitsbergen soltwedel 2013 ark-xxvii/3_bl 2012 bottom lander chambers (3 �0.04 m�2) nansen basin. amundsen basin this study ark-xxvii/3_mg 2012 multigrab (9 �0.024 m�2) nansen basin. amundsen basin this study macrobenthic abundance, biomass and production in the deep arctic ocean r. degen et al. 4 (page number not for citation purpose) citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://doi.pangaea.de/10.1594/pangaea.828348 http://doi.pangaea.de/10.1594/pangaea.828348 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 taken per box core on ark-viii/3 and ark-xiii/2. the total surface of a box core was sampled in ark-xxvii/2 (soltwedel 2013). on ark-xxvii/3 samples were taken with a multigrab (9 �0.024 m2) and benthic chambers of a bottom lander system (3 �0.04 m2). single chambers from lander and multigrab deployments were treated like replicate subsamples of box corers from other cruises. the samples from ark-viii/3 and ark-xxvii/2 were washed over 500 mm sieves (top 14 cm), the samples from arkxiii/2 with 250 mm sieves (top 2 cm) and 500 mm sieves (2 to max. 20 cm) and samples from ark-xxvii/3 only with 250 mm sieves (top 10 cm). all samples were stored in 4% (at ark-xxvii/2 10%) borax-buffered formalin. in laboratories, macroinvertebrates were counted, weighed (wet weight) and identified to the lowest possible taxonomic level. generally, all metazoan animals retained on a sieve with 250 or 500 mm mesh size were included in the analysis; only significantly larger animals belonging to the size class ‘‘megafauna’’ (�2 cm) were excluded. we are aware that estimates of macrofauna distribution are affected by gear design, sampling area, sample depth and sieve mesh sizes (wei et al. 2010). abundance estimates seem more affected by differing sieve mesh sizes than biomass estimates (shirayama & horikoshi 1989; romerowetzel & gerlach 1991; gage et al. 2002). gage et al. (2002) showed that 95% of the biomass retained on a sieve with 250 mm mesh size could still be retained on a much coarser sieve of 1 mm mesh size, while about 40% of abundance would be lost when switching from a 250 mm sieve to a sieve with only 500 mm mesh size. because of this effect, we have to consider an underestimation of abundances by 500 mm samples. sample area and depth of sample horizon are thought to have comparatively less impact on both abundance and biomass (gage et al. 2002; hammerstrom et al. 2012). to exclude potential effects of sampling procedure on our results we performed a three-way anova of the factors sieve size, sample area and year of sampling on the residuals of an anova of abundance (p �0.97) and biomass (p �0.80) versus regions. the ark-viii/3 data set was provided as the median of all subsamples per station (kröncke 1994, 1998) while the remaining data set consists of mean values per station. no significant ‘‘median/mean effect’’ was detected by an a priori pairwise test mean versus median across all ark-xxvii/3 stations sampled with the bottom lander system (p �0.708). data harmonization all geographical coordinates were converted to decimal degree. the station data were plotted on a modified polar stereographic international bathymetric chart of the arctic ocean base map (www.ibcao.org; jakobsson et al. 2012) in the wgs84 coordinate system using esri arcgis 10.1. the taxonomic name of each species was matched with the world register of marine species (worms) as the first authority and also with the integrated taxonomic information service for reasons of comparability with other data sets. when abundance and biomass data were not already provided per m 2 from the start they were recalculated to individuals and g wet mass per m 2 . a complete list of species taxonomy, abundance, biomass and p can be found in the pangaea open access library (www.doi.pangaea.de/10.1594/pangaea.828348). environmental data water depth refers to the recorded depth at the time the sampling device was deployed at the seafloor; bottom water temperature (8c) data were compiled using the pangaea open access library (www.pangaea.de). if temperature was not measured during sampling, we used data from nearby conductivity�temperature�depth stations from the same cruise. if no such data were available, we searched for the spatially and temporally closest measurement available from other cruises. this approach is reasonable as the seasonal variations in bottom water temperature from stations below 800 m depth are negligible (langehaug & falck 2012). information about sea-ice concentration (%) per station was extracted from geotiff pictures of sea-ice concentration for the respective year and month (25 km raster cells). sea-ice maps used for the cruises from 2012 were provided by the institute of environmental physics at the university of bremen (www.iup.uni-bremen.de). for stations sampled before 2002, the pictures used were provided by the national snow and ice data center (www.nsidc.org/). the p/b model estimation of benthic p was performed using the empirical artificial neural network model developed by brey (2012). the difference and advantage of this model compared to other empirical models based on multiple linear regression is that it can model complex, non-linear and non-continuous relationships between independent and dependent variables by learning and generalizing from example data (brey 2012). the p/b model used here is based on an initial database of 1258 data sets, each providing information on annual p, biomass, m, annual p/b ratio, taxonomy and ecology per species as well as the applied methods. the final model (which is implemented in an excel spread sheet and can be accessed at r. degen et al. macrobenthic abundance, biomass and production in the deep arctic ocean citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 5 (page number not for citation purpose) http://www.ibcao.org http://doi.pangaea.de/10.1594/pangaea.828348 http://www.pangaea.de http://www.iup.uni-bremen.de http://nsidc.org/ http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 www.thomas-brey.de/science/virtualhandbook/ [brey 2001]) consists of three continuous and 17 categorical input parameters: m (log(m), [j]), temperature (1/t, [k]), water depth (log(d), [m]), five taxonomic categories (mollusca, annelida, crustacea, insecta, echinodermata), seven lifestyle categories (infauna, sessile, crawler, facultative swimmer, herbivore, omnivore, carnivore), four environmental categories (lake, river, marine, subtidal) and a marker for exploitation. all categorical variables were binary (0 or 1). the necessary ecological information for each species was extracted from the literature and online resources (see below and supplementary file for details). m was calculated for each species by dividing biomass by abundance. biomass data were previously converted to joule, using the conversion factor database of brey (2012, database version 4, www.thomas-brey.de/science/virtualhandbook). when no conversion factor was found for a certain species the conversion factor of the next higher taxonomical level was used. species that did not belong to any of the five taxonomic categories of the model were grouped by the category their body form most resembled. accordingly we grouped porifera, tunicata, cnidaria and bryozoa by category mollusca, and sipuncula, nemertea, entoprocta and cephalorhyncha were grouped by category annelida. the exploitation marker indicates whether a species is commercially exploited and was set to zero for each species in this study. the model output is population p/b ratio (y �1 ), including upper and lower 95% confidence limits; population p was calculated by multiplying the p/b ratio with population biomass and community p by adding up all population values. for further details about the model, see brey (2012). functional traits information about lifestyle, motility and alimentation type needed as input into the p/b model (see above) was obtained from the literature and through internet search engines like worms (www.marinespecies.org), the marlin life information network (www.marlin.ac.uk) and the marine species identification portal (www.speciesidentification.org/). when no information was found for a certain species the next taxonomic level was tried until reliable information was found. a list of sources consulted (mainly for the two most prominent taxonomic groups in this study, the annelida and arthropoda) is included in the supplementary file. for the analysis of the trophic group structure of macrozoobenthic communities, the feeding types were assessed from the same sources as above and assigned to one of these four groups: carnivore/predator/scavenger; filter and suspension feeder; interface feeder; and deposit feeder (combining surface and subsurface deposit feeders). gis for mapping benthic abundance, biomass and p, arcgis desktop (release 10, 2011, environmental systems research institute, ca, redlands, usa), was used. shapefiles containing the geo-referenced sea-ice extent from 2013 and a 30-year mean were provided by the national snow and ice data center (www.nsidc.org/data/; fetterer et al. 2002). statistical analyses we tested for differences in abundance, biomass, m, p, p/b and feeding structure between (i) regions (nw spitsbergen, fram strait, yermak plateau, nansen basin, gakkel ridge, amundsen basin, lomonosov ridge, morris jesup rise), (ii) sea-ice zone (i.e., sea-ice concentration in month of sampling: ‘‘ice-free’’*sea-ice concentration b10%; marginal ice zone [miz]*pack ice with concentrations between 10 and 80%; ‘‘ice-covered’’*sea-ice concentration�80%), (iii) depth zone (upper slope b1500 m, lower slope 1500�3000 m, and basin �3000 m) and (iv) latitudinal zone (78�808, 80�828, 82�848, 84�868, 86�888, 88�908n). the similarity profile analysis (simprof) approach was used to test if the environmental parameters (water depth, temperature, sea-ice concentration, longitude, latitude) significantly differ between the compared regions and therefore justify the applied regional clustering. as p/b and m are known to be largely influenced by temperature, we tested for a correlation of temperature with p/b and m and also for regional differences in bottom temperature. statistical approaches included regression, anova, multi-way anova, ancova and post hoc tests (student’s t) using the jmp† software package, version 10.0 (1989�2007, sas institute inc., cary, nc, usa). because of the limited number of samples, we performed one-way anovas and ancovas with water depth used as co-variable to test for significant differences between stations (grouped by regions, latitudes and sea-ice concentration) after eliminating the generally acknowledged impact of depth on benthic communities. as depth and temperature co-vary in the arctic ocean, we performed an anova on the residuals of a temperature versus depth regression to test for temperature differences among regions. the makarov basin region was excluded from the statistical comparison of regions on account of the small sample size of only two stations; all other regions contained 4�20 stations (table 2). to exclude potentially distorting effects of sampling procedure (i.e., sieve size, macrobenthic abundance, biomass and production in the deep arctic ocean r. degen et al. 6 (page number not for citation purpose) citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 http://www.thomas-brey.de/science/virtualhandbook/ http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://www.thomas-brey.de/science/virtualhandbook http://www.marinespecies.org http://www.marlin.ac.uk http://species-identification.org/ http://species-identification.org/ http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://nsidc.org/data/ http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 sample area, year of sampling) on our regional comparison we performed a three-way anova of these factors on the residuals of an anova of abundance versus depth and biomass versus depth. data from regions that were sampled in 1991 and 2012 (nansen and amundsen basins) were additionally tested with ancova for an effect of time. data were transformed using power (box� cox) and log transformation. anosim was used to test for differences in the relative contribution of different feeding types to overall biomass and p. simprof and anosim were performed with primer, version 6 (clarke & gorley 2006). results effects of environment and sampling procedure the simprof test based on latitude, longitude, temperature and sea-ice concentration found eight significantly different groups (pb0.001) that correspond to the nine regional groups, except for the two makarov basin stations, which were grouped together with lomonosov ridge stations. temperature differed significantly between regions (anova with the residuals of a temperature vs. depth regression; f �2.17; p �0.0449). the three-way anova of the residuals of an anova of abundance per regions (f �20.81; p �0.001) and biomass per regions (f �9.96; p �0.001) on the factors sieve size, sample area and year of sampling did not find them explaining any variance in abundance (f �0.25; p �0.97) and biomass data (f �0.54; p �0.8022). the a priori pairwise test of median versus mean abundances did not detect significant differences for the ark-xxvii/3 stations (f �0.15; p �0.708). ancova with depth as a co-variable found abundance and biomass in nansen basin significantly higher in 1991 compared to 2012 (f �11.52; p �0.007 and f �5.44; p �0.042), but in amundsen basin significantly higher in 2012 compared to 1991 (f �6.58; p �0.021 and f �11.13; p �0.004). abundance mean abundance (individuals [ind.] m �2 ) per region varied between 10 (gakkel ridge) and 1053 ind. m �2 (yermak plateau) (table 2, fig. 2). the highest abundance by far was found at yermak plateau at a water depth of 517 m (4136 ind. m �2 ). stations from nw spitsbergen, morris jesup rise and fram strait showed relatively high average abundances of 552, 410 and 326 ind. m �2 , respectively. all other regions showed lower mean abundances that ranged between 10 and 203 ind. m �2 . the lowest abundances were found at the stations in the central arctic, with means of 90 ind. m �2 and lowest counts of 0 ind. m �2 in amundsen basin and at gakkel ridge (table 2). because water depth was found to have a significant effect on abundances (anova, f �41.53; pb0.0001; table 3), it was accordingly used as a covariable in ancovas to test for differences between stations grouped by regions, latitudes and sea-ice concentration (table 3, fig. 3). abundance (ind. m �2 ) was significantly different between the different regions (f �9.99; pb0.0001), latitudinal zones (f �12.46; pb0.0001) and fig. 2 macrobenthic abundance (ind. m�2) and estimated production (mg c m�2 y�1). for bathymetry, see fig. 1. r. degen et al. macrobenthic abundance, biomass and production in the deep arctic ocean citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 7 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 areas of different sea-ice concentration (f �10.52; p �0.0005; fig. 3). the post hoc tests (student’s t) grouped the regions with highest abundance values per m 2 , i.e., nw spitsbergen and yermak plateau (mean abundance per station 552 and 1053 ind. m 2 ) as significantly different from the regions with stations at greater depths and higher latitudes (i.e., nansen basin, amundsen basin, lomonosov ridge and morris jesup rise, with average abundances between 61 and 410 ind. m �2 ). the gakkel ridge stations were also significantly different from all the other stations as they showed the lowest abundances (zero abundance in four of five stations and one station with 50 ind. m �2 ). regarding latitude, abundance was significantly higher at 78�828n compared to 82�908n, whereas the stations between 86 and 888n showed significantly lower values than all the other stations. the northernmost stations, between 88 and 908n, were ranked third highest, although not significantly different from the stations between 82 and 868n. when stations were grouped according to percentage of sea-ice concentration with water depth as a co-variable, the stations in the ice-free and miz groups did not show significantly different abundances, but were both grouped as significantly different from the ice-covered group (f �10.52; pb0.0001; table 3, fig. 3). of the major taxonomic groups annelida was by far the most prominent group, ranging from 21% at lomonosov ridge up to 68% at nw spitsbergen (fig. 4). the second dominant taxonomic group was arthropoda, with ranges of 25�50% at gakkel ridge, makarov basin, amundsen basin and fram strait, but lower contributions in all other regions (1�20%). porifera was the third most prominent group, with a high share of 27�54% at lomonosov ridge, makarov basin and morris jesup rise and lower contributions of 0�14% in the other regions. mollusca had a higher share of the total community, with 22% only at nw spitsbergen. they grouped with all other phyla (bryozoa, cephalorhyncha, chordata, cnidaria, echinoidea, entoprocta, nematoda, nemertea and sipuncula) in the lower range of 0�14% at other regions (fig. 4, supplementary table s2). biomass mean biomass per region ranged from 2 mg c m �2 at gakkel ridge up to 410 mg c m �2 at yermak plateau (table 2). the highest biomass by far was found at yermak plateau and nansen basin stations (max. 2009 and 3026 mg c m �2 ), while all other regions showed low mean biomass, ranging between 2 and 65 mg c m �2 . because water depth was found to have a significant effect on biomass (anova, f�19.55; pb0.0001, table 3), it was used as co-variable in the following ancovas (table 3, fig. 3). ancovas detected significant differences in biomass between regions (f �5.07; pb0.0001) (table 3, fig. 3). post hoc tests grouped the stations from yermak plateau (mean biomass 410 mg c m �2 ) as significantly different to those of amundsen basin, morris jesup rise and gakkel ridge. no significant difference was detected to stations from nw spitsbergen, fram strait, nansen basin and lomonosov ridge. with respect to latitude, a significant difference was found between stations (f �5.53; p �0.0002). here the stations between 808 and 828n were found to be significantly higher in biomass than all the stations of the areas 82�84, 84�86 and 86�888n, but were not found to be significantly different from the southernmost (78�808n) and northernmost (88�908n) stations. comparing stations by seaice concentration showed significantly higher biomasses for the stations in the miz group (f �3.11; p �0.0496) compared to the ice-covered group. the ice-free group was not significantly different from the other two groups (table 3, fig. 3). annelids contributed most to community biomass at morris jesup rise (86%) and nw spitsbergen (74%), and between 10 and 60% elsewhere. arthropoda contributed 58% of the biomass in amundsen basin, 40% at gakkel ridge and 34% in fram strait, but only between 0 and 17% in all other regions. echinoderms dominated biomass in nansen basin (66%), but showed rather low percentages at all other regions table 3 differences in macrofaunal abundance, biomass and estimated production between regions (see table 2, figs. 1, 2), latitudinal bands (78�808, 80�828, 82�848, 84�868, 86�888, 88�908n) and areas differing in sea-ice concentration (ice-free b10%, marginal ice zone, icecovered �80%) as identified by one-way ancova with water depth as covariate. differences between depth ranges (upper slope b1500 m, lower slope 1500�3000 m, basin �3000 m) were tested with anovas. f p ancova region abundance 9.9903 b0.0001 biomass 5.0686 0.0001 production 5.3198 b0.0001 latitude abundance 12.463 b0.0001 biomass 5.531 0.0002 production 5.9492 b0.0001 sea-ice concentration abundance 10.5161 b0.0001 biomass 3.1089 0.0496 production 4.2491 0.0173 anova depth abundance 41.5304 b0.0001 biomass 19.5467 b0.0001 production 25.8839 b0.0001 macrobenthic abundance, biomass and production in the deep arctic ocean r. degen et al. 8 (page number not for citation purpose) citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 (0�12%). porifera dominated the community biomass in makarov basin (60%) and contributed a lot in fram strait (45%), at lomonosov ridge (32%) and nansen basin (21%). mollusca showed relevant shares of 29% at lomonosov ridge; in other regions they contributed 54%. all other groups did not contribute significantly fig. 3 comparison of (a) macrobenthic abundance, (b) biomass and (c) production between depth zones (upper slope, lower slope, basin), sea-ice zones (ice-free, marginal ice zone [miz], ice-covered) and latitudinal bands (78�808, 80�828, 82�848, 84�868, 86�888, 88�908n) in a box-plot (minimum, maximum and mean). letters above bars indicate significant differences between groups as identified by anova (depth zone) and ancova with depth as co-variable (sea-ice zone, latitude) and (student’s t) post hoc test on differences between means. plots are based on transformed (box�cox) data to meet anova/ancova preconditions; the y axis shows the corresponding non-transformed raw data (making the scale non-linear). r. degen et al. macrobenthic abundance, biomass and production in the deep arctic ocean citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 9 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 to community biomass and ranged between 0 and 10% in all regions (fig. 5, supplementary table s2). regarding trophic structure, deposit feeders were the dominant group, while interface feeders had significantly lower biomasses (f �14.61; pb0.0001). deposit feeders had a much higher share, with 66% of total biomass at nansen basin and 4�60% in the other regions except makarov basin. carnivores/predators/scavengers contributed most at morris jesup rise (84%) and amundsen basin (67%). filter feeders dominated the biomass at makarov basin (60%) and lomonosov ridge (53%; supplementary fig. s2). anosim did not detect differences in the relative contribution of different feeding types between any of the tested groups (depth, latitude, sea ice and region; global rb0.20). mean body mass (m) m of the stations from nansen basin, lomonosov ridge and yermak plateau with values between 0.4 and 2.5 mg c were significantly higher than at nw spitsbergen, morris jesup rise and gakkel ridge, with values of 0.03�0.1 mg c (f �3.12; p �0.0028). while no significant differences in m were found within the different water depths (f �0.73; p �0.4835) and sea-ice zones (f �1.87; p �1398), we detected significant differences between latitudinal zones (f �2.83; p �0.0207). post hoc tests ranked the groups 86�888n and 78�808n to be significantly lower than the groups 88�908n, 80�828n and 82�848n. m was not significantly related to bottom water temperature (f �0.01; p �0.9144). fig. 4 relative abundance of major groups annelida, arthropoda, porifera, mollusca, cnidaria and echinodermata. the group ‘‘others’’ combines bryozoa, cephalorhyncha, chordata, entoprocta, nematoda, nemertea and sipuncula. fig. 5 relative biomass of major groups annelida, arthropoda, porifera, mollusca, cnidaria and echinodermata. the group ‘‘others’’ combines bryozoa, cephalorhyncha, chordata, entoprocta, nematoda, nemertea and sipuncula. macrobenthic abundance, biomass and production in the deep arctic ocean r. degen et al. 10 (page number not for citation purpose) citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 benthic secondary production (p) mean macrobenthic p was lowest at gakkel ridge with 2 mg c m �2 y �1 and highest at yermak plateau with 385 mg c m �2 y �1 (table 2, fig. 2). the highest p per station was found at yermak plateau (reaching up to 2534 mg c m �2 y �1 ), followed by nansen basin, with values reaching 1585 mg c m �2 y �1 . p at nw spitsbergen and lomonosov ridge was rather similar, with means of 70 and 73 mg c m �2 y �1 , respectively. all other regions ranged in their means between 2 and 46 mg c m �2 y �1 . because water depth was found to have also a significant effect on p (anova, f �25.88; pb0.0001; table 3), it was used again as a co-variable in ancovas (table 3, fig. 3). ancovas showed that there were significant differences between regions (f �5.32; pb0.0001; table 3). post hoc tests grouped the regions with highest mean p (yermak plateau, nw spitsbergen and lomonosov ridge) and the stations with lowest mean p (morris jesup rise and gakkel ridge) to be significantly different from each other. also when grouped by latitude, significant differences were found by ancova (f �5.95; pb0.0001). post hoc tests revealed that the benthic p from stations at 80�828n, 78�808n and 88�908n was significantly higher than in the groups at 84�888n. comparison of stations grouped by their sea-ice concentration also showed significant differences in p (f �4.25; p �0.0173). as for biomass, post hoc tests showed significantly higher benthic p in the miz group (mean 0.5 g c m �2 y �1 ) compared to the icecovered group (mean 0.06 g c m �2 y �1 ; table 3, fig. 3). annelids contributed most to the overall p at nw spitsbergen (73%), at morris jesup rise (67%), at yermak plateau and gakkel ridge (both 64%) and at amundsen basin (51%) (fig. 6, supplementary fig. s2). at the other regions they contributed between 14 and 25% to the overall p. porifera were the most productive group at makarov basin (70%), nansen basin (49%) and lomonosov ridge (47%). arthropoda contributed 45% at fram strait, 39% at amundsen basin and 36% at gakkel ridge, but only between 0 and 16% in all other regions. all other groups contributed much less to the overall p. echinoderms contributed 23% to the overall p at nansen basin but only between 0 and 6% in other regions. molluscs only showed a considerable percentage at lomonosov ridge (12%) but ranged at all other stations between 0 and 3%. suspension feeders had the largest share in p, while deposit feeders showed the significantly lowest values (f �30.22; pb0.0001). in the three depth zones, suspension feeders contributed most in the lower slope group (50%) and comparably less to the upper slope group (17%) and ‘‘basins’’ (24%). at a regional scale, filter and suspension feeders contributed most to p at makarov basin (70%), nansen basin (64%) and lomonosov ridge (55%), predators at morris jesup rise (65%), deposit feeders at gakkel ridge (64%), amundsen basin (50%) and yermak plateau (48%), and interface feeders at nw spitsbergen (42%; fig. 7). anosim did not detect differences in the relative contribution of different feeding types in any of the categories tested (depth, latitude, sea ice, region; global r always b0.20). production to biomass ratio (p/b) p/b ratios ranged from 0.14 to 2.22 and were highest at morris jesup rise, lomonosov ridge and nw spitsbergen, with means per region ranging from 1.17 to 1.42 y �1 . gakkel ridge was the region with the significantly fig. 6 relative production of major groups annelida, arthropoda, porifera, mollusca, cnidaria and echinodermata. the group ‘‘others’’ combines bryozoa, cephalorhyncha, chordata, entoprocta, nematoda, nemertea and sipuncula. r. degen et al. macrobenthic abundance, biomass and production in the deep arctic ocean citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 11 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 (f�3.13; p�0.0057) lowest p/b ratio (mean�0.29 y�1). anova and ancova did not detect differences in p/b between depth zones (f �1.34; p �0.265), latitude zones (f �1.56; p �0.1690) and zones of different sea-ice concentration (f�1.15; p �0.3212). among major taxonomic groups porifera and arthropoda had highest mean ratios of 1.28 and 1.25 y �1 . regarding trophic structure, deposit and suspension feeders showed significantly higher ratios than interface feeders and predators (f�2.96; p�0.03). p/b was significantly positively related to bottom water temperature (f �10.01; p �0.002), but not to m (f �3.28; p �0.0733). discussion macrofauna standing stock and p in the arctic deep-sea decrease with increasing water depth. in addition, we detected significant regional differences for all studied community properties (abundance, biomass, m, p and p/b). stations in the vicinity of the highly productive miz (latitudes 80�828n) showed p levels comparable to shallower regions and lower latitudes (table 4). in the permanently ice-covered central arctic amundsen basin, mean macrobenthic p was estimated to be as low as 25 mg c m �2 y �1 (table 2). assuming an average production-to-consumption ratio (p/c) of macrofauna of about 0.2 (0.23990.190, n �97; unpublished data collection of t. brey), this p would require a particulate organic carbon (poc) input of at least 165 mg c m �2 y �1 for the macrofaunal consumption only, which is presumably 20% of all benthic size classes including bacteria (piepenburg et al. 1995). based on the assumption that b10% of surface primary production reaches the deep-sea floor (bauerfeind et al. 2009), a gross primary production (gpp) of around 8 g c m �2 y �1 would be sufficient to cover this benthic demand. this number is well in the range of reported gpp estimates of 1�25 g c m�2 y�1 for the central arctic (wassmann et al. 2010). sufficiently high poc fluxes of �1 g c m �2 y �1 were also recorded via sediment traps situated at 1550 m of depth (fahl & nöthig 2007). in contrast to the central arctic stations, we estimated a mean p of 385 mg c m �2 y �1 at the yermak plateau. taking into account that at shallower depths (mean 1500 m) a higher percentage of gpp can reach the seafloor, a gpp of approximately 30�90 g c m�2 y�1 would be required to enable the estimated community p. in the arctic, such a high primary productivity can be found regionally along the highly productive seasonal ice zone and in productive shelf areas like in the barents sea (klages et al. 2004; wassmann et al. 2010), which are both in the vicinity of and most likely affecting our sample stations. we conclude that particle flux induced by vertical and lateral transport processes is the key factor structuring benthic communities in the deep arctic ocean, explaining both the very low values in the ice-covered arctic basins and the higher values in the seasonal ice zone. depth-related patterns our study confirms the trends shown earlier (gage & tyler 1991; klages et al. 2004; bluhm et al. 2011): significantly lower mean abundances and biomasses are found in the deep basins compared to the upper slopes adjacent to the large arctic shelves (f�41.53; pb0.0001; respectively f �19.55; p b0.0001; table 3, fig. 2). fig. 7 macrofauna feeding types (%) based on production data per region. macrobenthic abundance, biomass and production in the deep arctic ocean r. degen et al. 12 (page number not for citation purpose) citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 mean abundance at the upper slope below 1500 m water depth ranges between 100 and 4130 ind. m �2 (table 2, fig. 2), consistent with abundances summarized in bluhm et al. 2011 and budaeva et al. 2008, and comparable to or even higher than abundances at lower latitudes from previous studies at similar depth ranges (see e.g., levin & gooday 2003). estimated benthic p was shown to follow the same pattern, i.e., significant differences between shallower and deeper stations (f �25.88; pb0.0001) (table 2, fig. 3). this corroborates the pattern of community p decreasing exponentially with water depth, as reported previously by brey & gerdes (1998) for a combined data set from antarctic, arctic and non-polar regions and by cusson & bourget (2005) who analysed global patterns of community p. extreme food limitation as found in the deep sea creates selection pressure towards smaller body sizes (thiel 1975; wei et al. 2010). smaller size often coincides with a higher growth rate and thus a higher p/b ratio (brown et al. 2004). accordingly, m should decrease and community p/b should increase with increasing water depth (peters 1983). however, m and p/b ratios did not significantly relate to water depth (f �0.73; p �0.4835 and f �1.34; p �0.265), in accordance with polloni et al. (1979) who did not find a decline in mean macrofaunal organism size from 400 to 4000 m. distinctly larger body size seems to be restricted to very shallow (neritic or coastal) waters. accordingly, data sets that exclude the upper 500 m like in this study may not show depth effects on m, and models that include shallow depths may overstate the depth effect in the deep sea (wei et al. 2010). on the other hand, kaariainen & bett (2006) found clear evidence of smaller body size in the deep sea when evaluating body size accumulation curves, stressing the need for size structure analysis. while no correlation of p/b ratios and water depth was found here, cusson & bourget (2005) found a negative relation between p/b and water depth (and a positive relation with temperature), and presume that certain life history traits may explain patterns in p/b ratios better than environmental variables. regional patterns here we detected significant regional differences*beyond those caused by water depth*for all studied community properties (abundance, biomass, m, p and p/b). the regions yermak plateau and nw spitsbergen (latter only in abundance) showed significantly higher values than the regions in higher latitudes (i.e., amundsen basin and gakkel ridge; table 3, fig. 3). this pattern is corroborated when stations were grouped by latitude (significantly higher values at 80�828n and for abundance at 78�808n) or by ice zone (significantly higher values in the miz group; table 3, fig. 3). the generally higher values at yermak plateau might be explained by its vicinity to the highly productive barents and spitsbergen shelves and the high primary production in this region (gpp 30�100 g c m�2 y�1) (wassmann et al. 2010). the high gpp is supported by atlantic water supply and the fertile conditions generally found along the miz (sakshaug 2004), which covers a large fraction of northern fram strait (sakshaug 2004; wassmann et al. 2010). along ice edges poc fluxes of �300 mg c m �2 d �1 are table 4 mean community production (p) and productivity (p/b) values found in literature, ordered after increasing water depth. when originally given in other units, data were converted to carbon using conversion factors from the database of brey (2012, database version 4, www.thomas-brey.de/ science/virtualhandbook). region latitude water depth (m) p (g c m �2 y �1 ) p/b authors wadden sea tidal flat, germany 548n 1 8�234 0.4�1.8 asmus 1987 north-east coast, great britain 548n 15 1.97�4.25 0.9�1.7 rees 1983 laizhou bay and bohai sea, china 37�398n 20�25 2.25�3.47 0.9�1.2 hua et al. 2010 new york bight, usa 408n 25 8.3 1.4 steimle 1985 phangnga bay, thailand 88n 30�50 1.6 5 petersen & curtis 1980 bay of fundy, canada 458n 0�70 9�18 � wildish et al. 1986 north sea 51�578n 0�100 0.6��20 0.7�2.5 duineveld et al. 1991 sørfjord, norway 698n 18�128 4.74 0.4 nilsen et al. 2006 continental shelf, great britain 508n 10�137 0.4�3.8 1.2�1.9 bolam et al. 2010 barents sea bank (infauna) 75�768n 40�150 0.2�5.3 � kedra et al. 2013 southern plateau, new zealand 508s 750 0.25 1 bradford-grieve et al. 2003 global study 778s�698n 0�930 b0.01�1869 b0.1�36.7 cusson & bourget 2005 magellan region, chile 48�568s 8�1140 0.4�1.1 0.2�0.3 thatje & mutschke 1999 weddell sea, antarctica 69�788s 200�2900 0.12�4.83 0.2�0.6 brey & gerdes 1998 rockall trough, north-east atlantic 548n 2900 0.122 0.5 gage 1991 arctic deep sea, marginal ice zone 80�828n 500�3500 b0.01�2.5 0.5�1.8 this study arctic deep sea, north 82�908n 500�5400 b0.01�0.6 0.1�2.2 this study r. degen et al. macrobenthic abundance, biomass and production in the deep arctic ocean citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 13 (page number not for citation purpose) http://www.thomas-brey.de/science/virtualhandbook http://www.thomas-brey.de/science/virtualhandbook http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 recorded, greatly exceeding those found in open water (intermediate export fluxes 12�27 mg m�2 d�1; klages et al. 2004). the estimated benthic p in the miz group (highest value 2.5 g c m �2 y �1 , mean 0.5 g c m �2 y �1 ; depth of 500�3500 m) is in the lower range of but still comparable to benthic p estimates from the shallow barents sea bank (0.02�5.3 g c m�2 y�1) in depths between 40 and 150 m (kedra et al. 2013; table 4), and to shallow areas from temperate regions like the uk continental shelf with means ranging from 0.4�3.8 g c m�2 y�1 (bolam et al. 2010; table 4). regarding regional groups, the highest mean p was found at yermak plateau with 385 mg c m �2 y �1 . the values from the second most productive area (nansen basin, mean p of 138 mg c m �2 y �1 ) from depths between 3000 and 4000 m are*although covered with sea ice throughout most of the year*comparable to values reported from the rockall trough in the north-east atlantic (122 mg c m �2 y �1 ) in depths of 2900 m (gage 1991). these comparisons indicate that benthic communities from the arctic deep sea can be comparable in p to other regions, if they are in the vicinity to the highly productive seasonal ice zone and the continental shelf. the third most productive areas are the southernmost stations in nw spitsbergen and the northernmost stations on the lomonosov ridge (70 and 73 mg c m �2 y �1 ). while the stations north-west of spitsbergen benefit from the conditions mentioned previously, the stations in the high arctic are far from any input from the miz and the productive shelf areas. we assume that benthic p at the lomonosov ridge could be fuelled by organic matter that gets transported with sea ice along the transpolar drift, enhancing export via seasonal melting processes. the stations far off the seasonal ice edge, e.g., in amundsen or makarov basin or on the gakkel ridge, show as low p as anticipated for the most oligotrophic deep-sea regions, as primary production under the permanent ice cover is very low (1�25 g c m�2 y�1) (wassmann et al. 2010). recent studies have found indications for much higher carbon fluxes associated with sea-ice minima in 2007 (lalande et al. 2009) and 2012 (boetius et al. 2013), and the rapid export of sea-ice algae to the seafloor. our results corroborate these observations, as the significantly higher benthic biomass in the central and eastern amundsen basin in 2012 compared to 1991 (f �11.13; p �0.004) may indicate an increase in vertical flux over these two decades. however, there are just five samples from 2012 and these were not taken in exactly the same area of amundsen basin as in 1991. hence, this finding should not be over-interpreted; distinctly higher sampling effort is required to produce more reliable data. nevertheless, the ongoing decline in sea-ice cover and thickness in the central basins are likely to cause future changes in macrozoobenthos abundance, biomass and p. while we found no correlations of m and p/b with water depth, we did detect significant regional differences (f �3.12; p �0.0028; f �3.13; p �0.0057). highest p/b ratios were found in the region morris jesup rise, ranging from 0.8 to 2.2 y �1 . the most important factors influencing the community p/b ratio are body mass, temperature and food (brey & clarke 1993 and references therein). overall we found no correlation of p/b ratios with m (f �3.28; p �0.0733), but we did detect a positive relation of p/b to temperature (f �10.01; p�0.002). however, as the temperature difference among regions is small, and the region with the highest p/b values (morris jesup rise) is not the one with the highest temperatures (lomonosov ridge), we assume that additional drivers have to be considered. the third proposed explanatory factor, food input, is quite difficult to determine in the ice-covered arctic ocean. we presume the highest food fluxes to be in areas influenced by the miz and close to shelf regions, i.e., those regions where we found the highest p. but unlike p, p/b ratios where highest in the northern most regions under permanent sea ice (i.e., morris jesup rise and lomonosov ridge), where low poc fluxes of �1 g c m �2 y �1 were measured (fahl & nöthig 2007). to summarize, although we found a correlation of p/b with temperature, none of the usual drivers of p/b (m, temperature and food input) could satisfyingly explain the observed regional pattern. this may partially be due to the high degree of intercorrelation between temperature, depth, and food input in the arctic deep sea hampering statistical analysis. patterns in feeding structure structure and function of benthic communities can be analysed beyond the assessment of basic community parameters, by dividing organisms in groups with shared behavioural traits or with shared resource bases (cochrane et al. 2012). here we analysed feeding mechanisms, as they are one of the central determinants of marine ecosystem structure (bremner et al. 2003), and information can be found in literature or be inferred from feeding or mouth structures (supplementary file). cusson & bourget (2005) found highest p for suspension feeders and highest p/b ratios for omnivores and predators. they explain this result by the fact that this feeding guild is dominated by annelids and arthropods with short life spans, small body mass and high mobility, all factors assumed to enhance the metabolic rate and as such also macrobenthic abundance, biomass and production in the deep arctic ocean r. degen et al. 14 (page number not for citation purpose) citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 http://www.polarresearch.net/index.php/polar/rt/suppfiles/24008/0 http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 p/b ratios. the effect of mobility on p/b ratios is controversial though. on the one hand, motile species potentially use more energy for respiration than for growth, leading to lower p/b ratios. on the other hand, mobility enables access to higher quality food, which might lead to higher p/b ratios. this is an important factor especially in the arctic deep sea, where food falls in the form of carcasses or ice-algae deposits (boetius et al. 2013) form an important source of nutrition. however, we found suspension feeders to contribute most to overall p (f �30.22; pb0.0001), while deposit and suspension feeders displayed higher p/b ratios than interface feeders and predators (f �2.96; p �0.03). this result might be explained by the fact that highly mobile predators and scavengers are underrepresented in our study, as in the deep sea this group is predominantly represented in the megafauna size class (gage & tyler 1991). physical dynamics play an important role in determining trophic community structure, with fauna shifting to suspension feeders in hydrographically dynamic areas and deposit feeders in depositional areas (rosenberg 1995). accordingly, deep-sea areas with reduced flow and with scarce and low quality food input, such as abyssal plains, are dominated by deposit feeders, while suspension feeders are abundant in areas with high bottom current flow, as on continental slopes and midocean ridges (gage & tyler 1991; thistle 2003). our findings confirm this general view: deposit feeders contribute most to overall p in the amundsen basin (50%), and suspension feeders at the lomonosov ridge (55%). however, other regions show a less clear pattern. in the nansen basin, suspension feeders contributed 64% and deposit feeders only 24% to overall p. the highest p in the nansen basin was found at the stations on the lower barents sea and yermak plateau slope (fig. 2), presumably benefitting from bottom current flows and food advection from the barents sea shelf. generally, when stations were grouped into three depth zones (upper slope, lower slope, basin), the highest contribution of suspension feeders was found in the lower slope group (50%). the region with highest p*yermak plateau* shows a more even distribution of feeding types than the low productivity regions*gakkel ridge and amundsen basin (fig. 7). this indicates a complex benthic food web well adapted to handle the high poc input found along the miz in the vicinity of the productive continental shelf. although some patterns are apparent, the anosim analysis failed to detect significant differences in the relative contribution of different feeding types between regions, depth zones, latitudinal zones and areas of different sea-ice concentration. bremner et al. (2003) could show that the biological trait analysis better illuminates the ecological functions of benthic communities than taxonomical or trophic group approaches. accordingly the biological trait analysis might be a more suitable approach here, but our knowledge about behavioural and life history traits of deep-sea taxa is still limited. outlook this study is a first step in providing baseline data concerning macrobenthic community parameters in the arctic deep sea based on a data synthesis covering the years 1990�2012 and different regions of the arctic deepsea slopes and basins. a major limitation to assessing status changes in the arctic deep-sea ecosystem remains the poor spatial and temporal resolution of sampling. in light of the observed climatic changes and the rapid decrease of sea-ice volume and cover, it is now important to collect more data at higher spatial resolution. furthermore, quality control procedures, such as standardized study design (i.e., sample size, sample depth and sieve mesh size), should be implemented. we support the recommendations already stated in previous large-scale studies of the deep-sea macrozoobenthos (e.g., bluhm et al. 2011) to apply consistent sampling sizes and to use sieves with 250 mm mesh size as a standard, to account for the small body sizes of deep-sea taxa. we further want to stress the importance of geo-referenced data archives and international efforts to synthesize available data, to improve our understanding of current and future changes in the arctic ocean ecosystem. acknowledgements the authors thank the captains, crews and shipboard parties of the rv polarstern ark-viii, arkxiii/2, arkxxvii/2 and ark-xxvii/3 cruises for help with work at sea. the authors thank jölund asseng (alfred wegener institute) for information and help in importing sea-ice concentration data into arc gis and professor dr ursula schauer (alfred wegener institute) for helpful information about arctic seawater temperatures. the authors further thank sergey y. gagaev, alexey v. golikov and victor petrjashev from the zoological institute of the russian academy of sciences for the taxonomical work on ark-xiii/2 samples. the authors also thank the anonymous reviewers for their constructive comments. this work was supported by the european research council abyss advanced grant (294757) to ab. rd and tb were supported by the polmar graduate programme. r. degen et al. macrobenthic abundance, biomass and production in the deep arctic ocean citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 15 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 references arrigo k.r., van dijken g. & pabi s. 2008. impact of a shrinking arctic ice cover on marine primary production. geophysical research letters 35, l19603, doi: 10.1029/2008 gl035028. asmus h. 1987. secondary production of an intertidal mussel bed community related to storage and turnover compartments. marine ecology progress series 39, 251�266. bauerfeind e., nöthig e., beszczynska a., fahl k., kaleschke l., kreker k., klages m., soltwedel t., lorenzen c. & wegner j. 2009. particle sedimentation patterns in the eastern fram strait during 2000�2005: results from the arctic long-term observatory hausgarten. deep-sea research part i 56, 1471�1487. benke a. 2012. secondary production. nature education knowledge 3, 23. bluhm b.a., ambrose w.g. jr., bergmann m., clough l.m., gebruk a.v., hasemann c., iken k., klages m., macdonald i.r., renaud p.e., schewe i., soltwedel t. & wlodarskakowalczuk m. 2011. diversity of the arctic deep-sea benthos. marine biodiversity 41, 87�107. boetius a. 2013. the expedition of the research vessel ‘‘polarstern’’ to the arctic in 2012 (ark-xxvii/3). berichte zur polarund meeresforschung 663. bremerhaven: alfred wegener institute for polar and marine research. boetius a., albrecht s., bakker k., bienhold c., felden j., fernandez mendez m., hendricks s., katlein c., lalande c., krumpen t., nicolaus m., peeken i., rabe b., rogacheva a., rybakova e., somavilla cabrillo r., wenzhöfer f. & rv polarstern ark27-3-shipboard science party 2013. export of algal biomass from the melting arctic sea ice. science 339, 1430�1432. bolam s.g., barrio-frojan c.r.s. & eggleton j.d. 2010. macrofaunal production along the uk continental shelf. journal of sea research 64, 166�179. bradford-grieve j.m., probert p.k., nodder s.d., thompson d., hall j., hanchet s., boyd p., zeldis j., baker a.n., best h.a., broekhuizen n., childerhouse s., clark m., hadfield m., safi k. & wilkinson i. 2003. pilot trophic model for subantarctic water over the southern plateau, new zealand: a low biomass, high transfer efficiency system. journal of experimental marine biology and ecology 289, 223�262. bremner j., rogers s.i. & frid c.l.j. 2003. assessing functional diversity in marine benthic ecosystems: a comparison of approaches. marine ecology progress series 254, 11�25. brey t. 2001. population dynamics in benthic invertebrates. a virtual handbook. version 01.2. accessed on the internet at http://www.thomas-brey.de/science/virtualhandbook/ on 07 2013. brey t. 2012. a multi-parameter artificial neural network model to estimate macrobenthic invertebrate productivity and production. limnology and oceanography*methods 10, 581�589. brey t. & clarke a. 1993. population dynamics of marine benthic invertebrates in antarctic and subantarctic environments: are there unique adaptations? antarctic science 5, 253�266. brey t. & gerdes d. 1998. high antarctic macrobenthic community production. journal of experimental marine biology and ecology 231, 191�200. brown j.h., gillooly j.f., allen a.p., savage v.m. & west g.b. 2004. toward a metabolic theory of ecology. ecology 85, 1771�1789. budaeva n., mokievsky v., soltwedel t. & gebruk a. 2008. horizontal distribution patterns in arctic macrobenthic deepsea communities. deep-sea research part i 55, 1167�1178. clarke k.r. & gorley r.n. 2006. primer v6: user manual/ tutorial. plymouth, uk: primer-e. cochrane s.k.j., pearson t.h., greenacre m., costelloe j., ellingsen i.h., dahle s. & gulliksen b. 2012. benthic fauna and functional traits along a polar front transect in the barents sea*advancing tools for ecosystem-scale assessments. journal of marine systems 94, 204�217. cusson m. & bourget e. 2005. global patterns of macroinvertebrate production in marine benthic habitats. marine ecology progress series 297, 1�14. duineveld g.c.a., künitzer a., niermann u., de wilde p.a.w.j. & gray j.s. 1991. the macrobenthos of the north sea. netherlands journal of sea research 28, 53�65. fahl k. & nöthig k. 2007. lithogenic and biogenic particle fluxes on the lomonosov ridge (central arctic ocean) and their relevance for sediment accumulation: vertical vs. lateral transport. deep-sea research part i 54, 1256�1272. fetterer f., knowles k., meier w. & savoie m. 2002. sea ice index. digital media. boulder, co: national snow and ice data center. fütterer d. 1992. arctic’91: die expedition ark-viii/3 mit fs ‘‘polarstern’’ 1991. (arctic’91: the expedition ark-viii/3 of rv ‘‘polarstern’’ in 1991.) berichte zur polarforschung 107. bremerhaven: alfred wegener institute for polar and marine research. gage j.d. 1991. biological rates in the deep sea: a perspective from studies on processes in the benthic boundary layer. reviews in aquatic sciences 5, 49�100. gage j.d. & bett b.j. 2005. deep-sea benthic sampling. in a. eleftheriou & a. mcintyre (eds.): methods for the study of marine benthos. pp. 273�325. oxford: blackwell science. gage j.d., hughes d.j. & gonzalex vecino j.l. 2002. sieve size influence on estimating biomass, abundance and diversity in samples of deep-sea macrobenthos. marine ecology progress series 225, 97�107. gage j.d. & tyler p.a. 1991. deep-sea biology: a natural history of organisms at the deep-sea floor. london: cambridge university press. hammerstrom k.k., ranasinghe j.a., weisberg s.b., oliver j.s., fairey w.r., slattery p.n. & oakden j.m. 2012. effect of sample area and sieve size on benthic macrofaunal community condition assessments in california enclosed bays and estuaries. integrated environmental assessmental management 8, 649�658. hua e., zhou h., zhang z. & yu z. 2010. estimates of autumntime benthic secondary production in laizhou bay and adjacent bohai sea waters. journal of ocean university of china 9, 279�285. macrobenthic abundance, biomass and production in the deep arctic ocean r. degen et al. 16 (page number not for citation purpose) citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 http://www.thomas-brey.de/science/virtualhandbook/ http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 jakobsson m., mayer l.a., coakley b., dowdeswell j.a., forbes s., fridman b., hodnesdal h., noormets r., pedersen r., rebesco m., schenke h.-w., zarayskaya y., accettella d., armstrong a., anderson r.m., bienhoff p., camerlenghi a., church i., edwards m., gardner j.v., hall j.k., hell b., hestvik o.b., kristoffersen y., marcussen c., mohammad r., mosher d., nghiem s.v., pedrosa m.t., travaglini p.g. & weatherall p. 2012. the international bathymetric chart of the arctic ocean (ibcao) version 3.0. geophysical research letter 39, article no. l12609, doi: 10.1029/2012gl052219. kaariainen j.i. & bett b.j. 2006. evidence for benthic body size miniaturization in the deep sea. journal of the marine biological association of the united kingdom 86, 1339�1345. kedra m., renaud p.e., andrade h., goszczko i. & ambrose w.g. jr. 2013. benthic community structure, diversity, and productivity in the shallow barents sea bank (svalbard bank). marine biology 160, 805�819. klages m., boetius a., christensen j.p., deubel h., piepenburg d., schewe i. & soltwedel t. 2004. the benthos of arctic seas and its role for the organic carbon cycle at the seafloor. in r. stein & r.w. macdonald (eds.): the organic carbon cycle of the arctic ocean. pp 139�167. heidelberg: springer. kristoffersen y., coakley b.j., hall j.k. & edwards m. 2007. mass wasting in the submarine lomonosov ridge, central arctic ocean. marine geology 243, 132�142. kröncke i. 1994. macrobenthos composition, abundance and biomass in the arctic ocean along a transect between svalbard and the makarov basin. polar biology 14, 519�529. kröncke i. 1998. macrofauna communities in the amudsen basin, at the morris jesup rise and at the yermak plateau (eurasian arctic ocean). polar biology 19, 383�392. lalande c., belanger s. & fortier l. 2009. impact of a decreasing sea ice cover on the vertical export of particulate organic carbon in the northern laptev sea, siberian arctic ocean. geophysical research letters 36, l21604, doi: 10.1029/ 2009gl040570. langehaug h.r. & falck e. 2012. changes in the properties and distribution of the intermediate and deep waters in the fram strait. progress in oceanography 96, 57�76. levin l.a. & gooday a.j. 2003. the deep atlantic ocean floor. in p.a. tyler (ed.): ecosystems of the deep oceans. pp. 111�178. amsterdam: elsevier science. macdonald i.r., bluhm b.a., iken k., gagaev s. & strong s. 2010. benthic macrofauna and megafauna assemblages in the arctic deep-sea canada basin. deep-sea research part ii 57, 136�152. mcclain c.r., boyer a.g. & rosenberg g. 2006. the island rule and the evolution of body size in the deep sea. journal of biogeography 33, 1578�1584. nilsen m., pedersen t. & nilssen e.m. 2006. macrobenthic biomass, productivity (p/b) and production in a highlatitude ecosystem, north norway. marine ecology progress series 321, 67�77. notz d. 2009. the future of ice sheets and sea ice: between reversible retreat and unstoppable loss. proceedings of the national academy of sciences of the united states of america 106, 20590�20595. peters r.h. 1983. the ecological implications of body size. cambridge: cambridge university press. petersen g.h. & curtis m.a. 1980. differences in energy flow through major components of subarctic, temperate and tropical marine shelf ecosystems. dana 1, 53�64. piepenburg d., blackburn t.h., von dorrien c.f., gutt j., hall p.o.j., hulth s., kendall m.a., opalinski k.w., rachor e. & schmid m. 1995. partitioning of benthic community respiration in the arctic (northwestern barents sea). marine ecology progress series 118, 199�213. polloni p., haedrich r., rowe g. & clifford c.h. 1979. the size�depth relationship in deep ocean animals. internationale revue der gesamten hydrobiologie und hydrographie 64, 39�46. rees h.l. 1983. pollution investigations off the north-east coast of england: community structure, growth and production of benthic macrofauna. marine environmental research 9, 61�110. rex m.a., etter r.j., morris j.s., crouse j., mcclain c.r., johnson n.a., stuart c.t., deming j.w., thies r. & avery r. 2006. global bathymetric patterns of standing stock and body size in the deep-sea benthos. marine ecology progress series 317, 1�8. romero-wetzel m.b. & gerlach s.a. 1991. abundance, biomass, size-distribution and bioturbation potential of deepsea macrozoobenthos on the voring plateau. meeresforschung 33, 247�26. rosenberg r. 1995. benthic marine fauna structured by hydrodynamic processes and food availability. netherlands journal of sea research 34, 303�317. sakshaug e. 2004. primary and secondary production in the arctic seas. in r. stein & r.w. macdonald (eds.): the arctic organic carbon cycle. pp. 57�82. heidelberg: springer. shirayama y. & horikoshi m. 1989. comparison of the benthic size structure between sublittoral, upper-slope and deepsea areas of the western pacific. international review of hydrobiology 74, 1�13. sibuet m., lambert c.e., chesselet r. & laubier l. 1989. density of the major size groups of benthic fauna and trophic input in deep basins of the atlantic ocean. journal of marine research 47, 851�867. soltwedel t. 2013. the expedition of the research vessel ‘‘polarstern’’ to the arctic in 2012 (ark-xxvii/2). berichte zur polarund meeresforschung 658. bremerhaven: alfred wegener institute for polar and marine research. soltwedel t., bauerfeind e., bergmann m., budaeva n., hoste e., jaeckisch n., von juterzenka k., matthiessen j., mokievsky v., nöthig e., quéric n., sablotny b., sauter e., schewe i., urban-malinga b., wegner j., wlodarskakowalczuk m. & klages m. 2005. hausgarten: multidisciplinary investigations at a deep-sea, long-term observatory in the arctic ocean. oceanography 18, 46�61. soltwedel t., mokievsky v. & schewe i. 2000. benthic activity and biomass on the yermak plateau and in adjacent deepsea regions northwest of svalbard. deep-sea research part i 47, 1761�1785. r. degen et al. macrobenthic abundance, biomass and production in the deep arctic ocean citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 17 (page number not for citation purpose) http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 steimle f.w. 1985. biomass and estimated productivity of the benthic macrofauna in the new york bight: a stressed coastal area. estuarine, coastal and shelf science 21, 539�554. stein r. & fahl k. 1997. wissenschaftlicher fahrtbericht über die arktis-expedition ark-xiii/2 von 1997 mit fs ‘‘polarstern’’. (scientific cruise report of the arctic expedition ark-xiii/2 of rv ‘‘polarstern’’ in 1997.) berichte zur polarforschung 255. bremerhaven: alfred wegener institute for polar and marine research. thatje s. & mutschke e. 1999. distribution of abundance, biomass, production and productivity of macrozoobenthos in the sub-antarctic magellan province (south america). polar biology 22, 31�37. thiel h. 1975. the size structure of the deep-sea benthos. internationale revue der gesamten hydrobiologie 60, 575�606. thistle d. 2003. the deep-sea floor: an overview. in p.a. tyler (ed.): ecosystems of the world 28. pp. 5�37. amsterdam: elsevier science. wassmann p., duarte c.m., agusti s. & sejr m.k. 2011. footprints of climate change in the arctic marine ecosystem. global change biology 17, 1235�1249. wassmann p., slagstad d. & ellingsen i. 2010. primary production and climatic variability in the european sector of the arctic ocean prior to 2007: preliminary results. polar biology 33, 1641�1650. wei c.l., rowe g.t., escobar-briones e., boetius a., soltwedel t., caley m.j., soliman y., huettmann f., qu f., yu z., pitcher c.r., haedrich r.l., wicksten m.k., rex m., baguley j.g., sharma j., danovaro r., macdonald i.r., nunnally c.c., deming j.w., montagna p., lévesque m., weslawski j.m., wlodarska-kowalczuk m., ingole b.s., bett b.j., billett d.s.m., yool a., bluhm b.a., iken k. & narayanaswamy b.e. 2010. global patterns and predictions of seafloor biomass using random forests. plos one 5(12), e15323. doi: 10.1371/journal.pone.0015323. wildish d.j., peer d.l. & greenberg d.a. 1986. benthic macrofaunal production in the bay of fundy and the possible effects of a tidal power barrage at economy pointcape tenny. canadian journal of fisheries and aquatic sciences 43, 2410�2417. macrobenthic abundance, biomass and production in the deep arctic ocean r. degen et al. 18 (page number not for citation purpose) citation: polar research 2015, 34, 24008, http://dx.doi.org/10.3402/polar.v34.24008 http://www.polarresearch.net/index.php/polar/article/view/24008 http://dx.doi.org/10.3402/polar.v34.24008 surface magnetic anomaly study on the eastern part of the forlandsundet graben a . a. krasil'scikov*, a . p. kubanskij'* and y . ohta krasil'stikov, a. a , , kubanskij, a. p. & ohta, y. 1995: surface magnetic anomaly study on the eastern part of the forlandsundet graben. polar research 14(1), 55-68. a surface magnetic survey was carried out by use of a proton magnetometer over wide strandflats along the eastern coast of forlandsundet, western spitsbergen, to decipher subsurface structures and lithologies. distinctive linear high-anomaly segments and zones were recognised on the magnetic anomaly maps. these zones coincide well with the eastern marginal fault of the tertiary forlandsundet graben and associated faults north of st. jonsfjorden, while they reflect bedrock lithologies in the south. the high-anomaly segments, which constitute the zones, are locally aligned in a left-stepping. en echelon arrangement within the zones, indicating a dextral transpressional stress regime on the eastern marginal fault of the graben during a certain time. sudden termination and bends of the segments define a later transverse fault system. a . a . k r a d f t i k o u and a . p . kubanskij, polar marine geological expedition, ul. pobeda, 24, 189510 lomonosou. russia; y . ohta, norwegian polar institute, p.o. box 5072 majorstua. n-0301 oslo, norway. introduction pronounced coastal plains have developed on the eastern coast of forlandsundet, 1.5-6 km in width, extending n-s for approximately 75 km from engelskbukta to t h e northern side of isfjor den (fig. 1). these plains are divided by st. jonsfjorden and two large glaciers, aavats markbreen in the north and eidembreen in the south. the plains are also divided into four sep arate strandflats: s a r s ~ y r a (45 krn'), kaffi~yra (30 km2), svartfjellstranda (22 km2) and daud mannsoyra (118 km'), listed from north to south. these strandflats are slightly undulating and slope gently to the west toward forlandsundet. their elevation does not exceed 100 m in the piedmont areas of oscar i1 land. about 70% of the plains is covered by loose quaternary sediments up to 10-15 m in thickness. the geology of the area has been studied by hjelle et al. (1979), harland et al. (1979), ague & morris (1985), kanat & morris (1988), krasil'seikov & kovaleva (1976, 1979), wojcik (1981), ohta et al. (1986), ohta (1988), teben'kov & korago (1992), ohta et al. (1992), * english transcription: krasilshchikov * * english transcription: kubansky kleinspehn & teyssier (1992), gabrielsen et al. (1992) and lepvrier (1992), and various esti mations of the subsurface geology have been pro posed. the areas have complex structures resulting from caledonian thrusting which was overprinted by tertiary tectonic disturbances. the quater nary sediments are underlain by precambrian vol cano-sedimentary sequences, metabasic intrusive rocks and vendian tilloids, all metamorphosed to greenschist facies (fig. 1). a high-pressure metamorphic complex record ing a caledonian subduction zone, including green-brown dolomites (dolomite-magnesite rocks containing fuchsite, chromite and chromian spinel) and a small amount of serpentinites (ohta 1979; hirajima et al. 1988; dallmeyer et al. 1990; teben'kov & korago 1993), occurs i n motala fjella east of eidembukta. small scattered occur rences of the green-brown dolomites and serpentinites have been found in the strandflats north of st. jonsfjorden. flyschoid sediments of late ordovician to middle silurian age (scrutton et al. 1976; ohta et al. 1984; armstrong et al. 1986) are distributed to the east of the high-pressure complex in the st. jonsfjorden area. a thin, coarse-grained, unsorted conglomerate 56 a . a . krasil’sfikov et al. fig. i . generalized geological map of the eastern margin of the forlandsundet tertiary graben legend: 1 = steep faults. 1 = thruats. 3 = tcrliary sediments. 1 = carboniferous sediments. 5 = latc ordovician-middle silurian sediments. 6 = vcndian tilloids. 7 late proterozoic metasediments, 8 = garnet-biotite achi\ts. 9 = high-pressure metamorphic rocks. 10 = middle pro terozoic, i.alc-argillo-volcanic succession. 1 1 = middle pro terozoic quartzite-sandy phyllite succession. i ? = 5chists and sneisse, i n aroggcrhalvqa. occurs associated with a slice of serpentinite at the southeastern corner of sarsoyra (figs. 1 and 5a). about 1 km-thick black and green phyllites with thin carbonate and quartzite layers are dis tributed to the west of the conglomerate and a thick limestone-dolomite borders the tertiary rocks to the west. except for the serpentinite, these rocks have lithologies very similar to the flyschoids in motalafjella. scrutton et al. (1976) reported paleozoic fossils from this area, and some paleozoic microfossils have been found (a. a . makariev, pers. comm. 1993) in the thick limestone-dolomite in the northern sarseyra plain. thus, the present authors consider that this succession is of middle ordovician-middle silurian age. excluding the flychoids, these rocks are involved in both early (middle ordovician) and late ( middle-late silurian) caledonian, tightly folded and thrust structures (dallmeyer et al. 1990. bernard-griffiths et al. 1993), whereas the flyschoids were affected by the late caledonian deformation only. these structures were overprinted by the ter tiary deformation of the west spitsbergen fold and thrust belt (e.g. dallmann et a]. 1993). a narrow graben containing middle to upper car boniferous strata occurs along the foothills of svartfjella to western daudmannsoyra (fig. 1). these rocks show a strong compressional deform ation prior to the graben formation in paleogene time (ohta 1988; gabrielsen et al. 1992: lepvrier 1992). the eastern border of the tertiary for landsundet graben roughly follows the piedmont of mountains to the east. to the west of the border a thick paleogene succession occurs, up to 800 m in thickness and consisting mainly of sandstones and conglomerates. the present study has been conducted to deci pher subsurface structures beneath the strandflat areas widely covered by quaternary sediments. field measurements were performed by a spits bergen party of the polar marine geological expedition, st. petersburg, on sarsayra in 1984, daudmannsayra in 1988 and 1989, and kafficlyra svartfjellstranda in 1990 (internal reports of polar marine geological expedition, lomono sov. 1984,1988,1989 and 1990). present magnetic measurements covered all strandflats, extending ca. 4 k m east of the graben margin in daud rnannsoyra. the total survey area covers 224 km’ at a map scale of 1 : 25,000. surface magnetic anomaly study on the eastern part of the forlandsundet graben 57 survey methods the magnetic profiles crossing the strandflats from the piedmont to the coast in an e-w direc tion were placed every 250 m and tie lines (n-s directed) were spaced every 1 km. the measure ments were carried out every 25 m on the lines. proton magnetometers were used. the precision of the measurements is 2 2 . 6 3 . 5 nt. temporal variations were measured in com parison with the measurements made by the base stationed magnetometer. the variations of 100 200 nt were recorded during 80% of the working days. synchronity of the measurements with the baseand field magnetometers was determined every day and necessary corrections of the field measurements were made by a graphic method. processing the surface measurement data included, besides the correcting of temporal vari ations, the unification of relative level, the con struction of anomalous magnetic field graphs, and the tying of the observations of 1988 and 1989, which were based on the repeated measurements. the construction of the graphs and isolines was carried out automatically with the aid of processing programmes for aero-geographical data modified for surface magnetic survey on a computer es-1036 (srebnij et a]. 1985). the pro gramme includes correction for the normal field, field interpretation into uniform net nods by cal culation of the average-weighted value, and field tying by the method of filtrating different par ameters. original maps of graphs and isolines were constructed at the scale of 1 : 25,000 in the gauss-kryuger projection. the contour interval is lont, locally 1, 3 or 5 n t in sarsayra. an evaluation of the error of map construction was made on the matrix points, the coordinates of which coincide with the observation points and are equal to 1.2 nt. magnetic property of the rocks in order to determine the density and magnetic properties of the rocks, measurements of rock magnetic susceptibility were performed for 270 samples and at more than 2,000 outcrops. six rock types have been recognised in the measured samples: 1) mesozoic dolerites, 28 samples; 2) serpentinites, 17; 3) metabasic rocks, chloriteand chlorite-car bonate phyllites and metasomatic rocks (e.g. green-brown dolomites) together, 102; ,4) quartz-sericite phyllites and other psammo pelitic phyllites, 30; 5 ) carbonate rocks, 56; 6) quartzites, sandstones and conglomerates, 37. fig. 2 shows the correlation of density (d) and magnetic susceptibility (x) of the samples. the samples generally plot in two fields: a “non-mag netic” field with as much as 10 x si and a “magnetic” field exhibiting 40-1,000 x si fields. some rocks plot in the intermediate field. 1 0 4 0 x si. the rocks of types 1 and 2 are in the “magnetic” field. the rocks of type 3 plot widely over all fields. the reason is that the meta somatic rocks of type 3, i.e., green-brown dolo mites (listvenites of teben’kov & korago 1992), identified in the field are not all metasomatic green-brown dolomites, but actually common sedimentary dolomites which have lower mag netic susceptibilities. those having more than 50 x all rocks of types 4, 5 and 6 fall in the “non magnetic” field. among the rocks of anomalously high magnetic susceptibility, more than 70 x si. the doler ites of type 1 have high densities (2.95-3.10g/ cm3), whereas type 2 serpentinites have low den sities (2.50-2.70 g/cm3). the metabasic rocks and metasomatic rocks of type 3 have intermediate densities between dolerites and serpentinites. the magnetic susceptibility of serpentinites of type 2 (17 samples) varies from 45 x 10-‘si to more than 1,000 x si, indicating a wide variation of lithology. three types of rocks in this area can potentially cause a high magnetic anomaly: (1) mesozoic dolerites, (2) serpentinites and (3) green rocks including magnetite-bearing chlorite phyllites and chlorite-carbonate phyllites, metabasic rocks and metasomatic green-brown dolomites. it is note worthy that the magnetic susceptibilities of the high-pressure metamorphic rocks such as glau cophane schists and eclogites of motalafjella. which are not shown in fig. 2, generally have low values, i.e., 4-8 x si. si in type 3 are rich in magnetite. modelling of magnetic source body the depth of the magnetic source has been esti mated using a variety of methods (volk et al. 1973; logaeev & zacharov 1980). the main 58 a . a . krasil'scikov et al. , 3 . 2 ,3.4 10-6 si 1,000 500 100 5.0 go 5 1 0.5 0 ' 3 '. d d 0 0 0 0 0 *&* d d d d b 0 0 o t d.g/cmj f i r 2 . plot ot magnetic wsceptibility (a) and density (d) of the basement rocks. younger clastic sedimentary rocks and mesozoic dolerites legend: solid circles = mesozoic dolerites (type 1 ) . solid triangle$ = serpcntinite (type 2 ) . open triangles = metabasic rocks. chloriteand chlorite-carbonate phyllites and metasomatic rocks ( e . g green-brown dolomites, type 3 ) . solid squares = quartz-sericite phyllites and other psarnmo-pelitic phyllites (type 4 ) . open squares = carbonate rocks (type 5 ) , open circles = quartzites. sindstones and conglomerates (type 6 ) method is known as the "half-slope" method of peters (1949). based o n assumption that the anomalies can b e modelled by an isolated simple body of uniform magnetisation. another method widely used in the arctic (e.g. a m 1975; kovacs & vogt 1982) assumes that a source is either a two-dimensional dyke or the edge of a body. model calculations of the magnetic sources and parameters of the causative magnetic bodies were performed for some selected profiles. observed outcrops of the three possible causa tive rocks around the present area are not more than 50 m in width which indicates that they are small bodies. t h e average size of the magnetic rock bodies, estimated from local anomalies of the present a r e a , corresponds roughly to the observed outcrop sizes. in s a r s ~ y r a , actual mag netic sources were approximated by near vertical or steep dipping, plate-shaped magnetic bodies of various thicknesses (fig. 3). all anomaly sources inferred from the model calculations a r e near the surface with their tops at approximately 30 m depth and their bottoms in a range of u p t o 100 m depth. o n l y bottoms of two estimated sources in svartfjellstranda reach 120-130 m below the surface. results of magnetic anomaly measurement all strandflats from engelskbukta to isfjorden generally have slightly positive or quasi-normal magnetic anomalies (fig. 4a-d). t h e distinctive features superimposed o n this background are n-s t o nnw-sse trending, high-gradient linear anomalies of predominantly positive nature. these linear anomalies persist across the entire measured a r e a , though local differences are also distinguished in each strandflat. t h e specific nature of the magnetic anomaly patterns is described below from north to south, with ref erence to the mapped bedrock geology. to avoid repetition, the discussion and interpretation are arranged in separate chapters with references t o each of the strandflat areas. sarslyra (figs. 4a and 5a) magnetic characteristics. t h e background of the magnetic anomaly in s a r s ~ y r a consists of gentle anomalies from +20 t o -20 n t and of scattered small highs of u p to 40 n t , interrupted by n-s to nnw-sse elongated wide oval zones, 700-900 m surface magnetic anomaly study on the eastern part of the forlandsundet graben 59 100 10 1 oo 10 1 200 100 . ir . 10-6almsi .'* i 1 j 1 : l 1 . 1 : 1 1 1 . 1 1 1. 1 1 1 . 1 * . l 1 : l l , l l . li .10 6a/msi i ' . ( a tla metabasia fig. 3. measured data and a calculated profile of source rock bodies along the measurement line in northern sarsdyra (location a-a' shown in fig. 4a). ir = remnant magnetisation; ii = induced magnetisation. wide and 2 km long, displaying positive anomalies of 80-120 nt. t h e most characteristic features are a distinctly high gradient, u p t o 60 nt/m, and n-s and nnw sse trending positive segments of 25-200 m width with 100-1, 150 n t (the highest is local and not shown in fig. 4a). these segments comprise wide zones. a 200-500 m wide zone is recognised along the eastern piedmont for ca. 10 km, in a 340" direction (eastern high anomaly zone: e h a z in fig. 5a). this zone consists of many high positive anomaly segments with steep gradients. t h e segments form a double alignment t o the west of arthurbreen. narrow negative anomaly segments separate the positive anomaly segments in the northern and southern parts of the double alignment. the high anomaly segments show a left-stepping en echelon alignment in the west of arthurbreen to unnamed glacier a , and a similar tendency can be seen in the west of dahltoppen. a possible sinistral fault displwement between the segments can not be excluded a t t h e latter locality. distinct terminations of the high anomaly seg ments occur in front of the unnamed glacier b along a ne-sw line. similar, but less distinct discontinuity along an e-w line occurs to the west of the unnamed glacier a . a large, gentle. open high anomaly area occurs t o the west of arthurbreen (fig. 4a), west of the e h a z , elongated parallel t o the e h a z , and its eastern side is marked by a steep anomaly gradient. a less distinct, high anomaly zone is recognised in the middle of sarsoyra with a 345" direction (middle high anomaly zone: m h a z in fig. 5a) and consists of 2 or 3 high-anomaly segments in its northern and southern parts. a large, open. gentle high anomaly area occurs in the middle of the m h a z (fig. 4a) and its eastern margin has a relatively steep anomaly gradient. this margin trends parallel t o the m h a z , though it shows a left-stepping alignment. t h e southern end of this zone is abruptly terminated, and a sudden bend occurs at o n e of the high anomaly segments. another high anomaly zone occurs in the west ern part of s a r s ~ y r a with a 330" direction (western high anomaly zone: w h a z in fig. 5a) and includes more than 15 high anomaly segments. some segments show sudden bends or ter minations n e of sarsbukta along an ene-wsw trending line which seems to be continuous to the southern termination of the m h a z . some linear high anomalies may b e deduced across the lagoon at sarstangen (fig. 4a), but these a r e not certain d u e to the limited number of measurement lines. a high anomaly enclosed by a curved negative anomaly segment occurs at se sarsbukta. since it is located o n the coast. its trend is unknown. geological evidence. surface geological maps show that almost all observed rocks of high mag netic susceptibility occur in the high anomaly zones. t h e western margin of the e h a z gen erally coincides with the tertiary-basement boundary in its northern half. i n the south, the e h a z extends into the basement rocks and follows the eastern boundary fault of the late ordovician to mid-silurian succession. a thin serpentinite a n d a conglomerate occur along the boundary fault within the southernmost high 60 a . a. krosil'.eeikori er al. anomaly segment, the tertiary-basement bound ary, which has not been determined as either a fault or a n unconformity . is located approximately 1 km west of the southern part of the e h a z , and no magnetic expression o f the boundary has been obtained. in the m h a z . occurrences of two green phyl lites and a green-brown dolomite tit with the high basement exposure has been found in the north. tertiary sandstones occur along the coast in the north and t h e change of bedding trends suggest a fault around the northernmost part of t h e m h a z . two isolated exposures of green phyllite and a green-brown dolomite are located in the middle part of the w h a z . a n isolate green-brown dol omite occurs at the high anomaly location of se anomaly segments in its southern part. but no sarsbukta. 4 a kapp graarud ftg. 1. miiynetic anomaly maps of thc ctrandflats. legend: numbers on contours = nt. dotted areas = negative anomaly areas. dashed i i n ~ = margin3 o f glacicrs. niorainci and 1ix)m contours 4a. sarwyra. a-a'; protile line of fig 3. i h : k a f t i ~ y r a . 4,: svarrt]ell\trdnda i d : daudmannsoyra. surface magnetic anomaly stirdy on the eastern part of the forlandsirndet grtrheri 61 the base of the tertiary sediments at sar stangen is ca. 8 0 0 m below the surface. the quaternary deposits o n the strandflat are esti mated to be several metres in thickness, deduced from the coastal exposures, and are probably underlain by tertiary sediments in the middle and western parts of the strandflat. interpretations. t h e coincidence of the high magnetic anomaly segments and observed localit ies of the rocks with high magnetic susceptibility o n the strandflat supports that these rocks are solid exposures, but not glacial erratics. superposition of the ehaz and observed faults along the piedmont indicates that the high anomaly zones are magnetic expressions of faults underlying the quaternary cover. relatively duc tile green phyllites, serpentinites and sheared green-brown dolomites are supposed to be squee zed u p along the faults. t h e estimated magnetic source bodies shown in fig. 3 are in accordance with this interpretation. t h e shapes of the calculated bodies are 60-80" w-dipping plates, 10-60m thick, their tops at 0-30m and their bottoms at 18-100m depth. estimated efficient magnetisations, 300 850 x si. are in t h e range of measured mag netic susceptibilities of t h e possible causative rocks. general left-stepping en echelon alignment of the high anomaly segments within the e h a z may indicate a dextral slip movement at a certain time during the complex movements along the eastern marginal fault of the tertiary forlandsundet graben. t h e distinct bends and terminations of t h e high anomaly segments suggest later trans verse faults which displaced the n-s and nnw sse trending faults. kuf&yra (figs. 4b and 5b) magnetic characteristics. t h e magnetic field of this strandflat is quiet, near-normal, predomi nantly negative in t h e northwest and positive in t h e south and east. small segments of high positive anomaly occur along the piedmont, forming five clusters from n w to s e . most segments tend to show roughly ns elongation. t h r e e segments of high anomaly, up to more than 2 0 0 n t , occurring to the west of walde marbreen, form a short zone ( n h a z in fig. 5b). a high anomaly segment, u p t o 200 n t (local and not shown in fig. 4b) to the nnw of snippen on the southern coast is associated with o n e o r two negative anomaly segments with steep gradients. these can be assigned as a short zone ( s h a z in fig. 5b). t h e minimum magnetic susceptibility estimated for the causative rocks is ca. 360 x si which is conformable with the measured susceptibility of more than 500 x 1 0 p si from the rock samples of green phyllites of this area. t h e other clusters of high anomaly within the area from w of irenebreen to s w of andreas breen a r e isolated and their relations are uncer tain, but they could be included in a faint high anomaly zone ( f h a z in fig. sb). geological evidence. the mountains east of k a f f i ~ y r a consist of thick tilloids in their higher parts, with a general cleavage striking nw-se and dipping moderately sw. a succession of dominantly grey and black phyllites, with fre quent intercalations of marbles, green phyllites and occasional metabasic rocks (meta-diabase and -gabbro) occurs along the piedmont, and these rocks a r e in contact with the tertiary rocks t o the west. t h e tertiary sediments are supposed to underly ca. two-thirds of the western part of the strandflat (wojcik 1981). they have subparallel strikes and steep w-dips near the boundary t o the basement, while they a r e in ene-wsw t o ese w n w strikes and moderate n dips along the western coast. several green phyllite exposures have been observed immediately east of the tertiary-base ment boundary in the west of waldemarbreen, which coincides with the western margin of the n h a z . a few serpentinite lenses and green and purple phyllites are incorporated in a wide shear zone along t h e tertiary-basement boundary nw of snippen, which is superposed by the s h a z . many lenses of green phyllites and metabasic rocks occur at the locations of high anomaly seg ments along the piedmont from the west of irene breen to the northwest of andreasbreen. a serpentinite locality has been reported in front of irenebreen. i n s w of andreasbreen, some marble lenses occur along t h e steep magnetic anomaly slopes. interpretation. t h e weakly negative magnetic field in the western half of the strandflat can be explained by a thick tertiary cover consisting of rocks with low magnetic susceptibility. t h e n h a z and t h e s h a z are explained as 62 a. a. krasil’eikov et al. b heggodden m fig. 5 . high magnetic anomaly segments and zones. legend: 1 = quaternary cover of the strandflats. 2 = tertiary exposures. 3 = carboniferous rocks. j = late ordovician-middle silurian succession. 5 = vendian tilloids. 6 = late proterozoic succession. 7 = marble-phyllitc succession. 8 = quartzite-phyltite succession. p-12 = isolate localities of rocks with high magnetic susceptibility. 9 = green phyllites, 10 = mesozoic dolerites, 11 = green-brown dolomites. 12 = serpentinites, 13 = obscrved and estimated faults, 14 = unconformities. 15 = high positive anomaly segments. 16 = later transverse faults deduced from the bends and sudden terminations of high anomaly segments. ju. sarsoyra e h a z = castern high anomaly zone: mhaz = middle high anomaly zone: w h a z = western high anomaly zone. 5b. kaffieyra. nhaz = northern high anomaly zone. three segments of high anomaly. up to more than 200 nt. occurring to the west of waldemarbreen and forming a short zone. shaz = wuthern high anomaly lone. negative anomaly segments with steep gradients assigned as a short zone and associated with a high anomaly segmcnt. up to 200 nt (local and not shown in fig. j b ) to the north-northwest of snippen on thc fouthern coast. f h a 2 = il faint high anomaly zone. which includes other isolated clusters of high anomaly within the area from west of irenebreen 10 south-west of andreashreen small circles: metaconglomerates. surface magnetic anomaly study on the eastern part of the forlandsundet graben 63 90 7 eidembukta i" 5c. svartfjellstranda 5d. daudmanns~yra. ws = western subarea. mws = middle-western subarea. mes = middle-eastern subarea. es = eastern subarea. 64 a. a. krasil'fkikov et al. magnetic expressions of the tertiary-basement boundary shear zones. both show a left-stepping alignment of the high and low anomaly segments within the zones. their continuation in the middle part of the strandflat is not clear. but a weak alignment of small high and low anomalies for ca. 5 km nw from snippen and the 0 anomaly contour line t o the west of irenebreen (fig. 4b) are supposed t o reflect the position of boundary o n the surface. discontinuous, high anomaly segments along the piedmont in the f h a z , are caused by mag netite-bearing green phyllites and metabasic rocks in the marble-phyllite succession. t h e fhaz indicates t h e distribution of this succession. a serpentinite occurrence west of irenebreen may indicate a fault. a nw-se trending. narrow quiet area occurs between the s h a z and the f h a z , t o the west of andreasbreen. several impersistent meta-conglomerates have been observed in this area together with marbles. this conglomerate bearing part seems t o have n o rocks of high mag netic susceptibility and has been considered as the late ordovician-middle silurian succession by some geologists ( a . hjelle. pers. comm. 1995). discontinuities between the clusters of high anomaly segments within the f h a z may indicate the positions of transverse faults similar to those suggested by wojcik (1981). a distinct n-s trend shown by the 1 0 n t contour in the magnetically negative area of the northwestern part of the strandflat (fig. 4b) may indicate the general structural trend of the under lying basement. suartfjellstranda ( f i g s . 4c and 5c) magnetic characteristics. short and narrow anomalies u p t o 50 n t are scattered in a relatively quiet magnetic field in the northern half of this strandflat. north of ca. n78"26'. in contrast, in the southern half. distinct high-anomaly segments, up to 200 nt. are aligned in a left-stepping en echelon zone at 335" direction along the western coast. the minimum magnetic susceptibility estimated from the most intense anomaly of this strandflat does not exceed 100 x 10-'si. the low intensity anomalies in this area give deeper calculated bottoms of magnetic source bodies. 120-130 m beneath the surface. than those of sarsciyra and kaffisyra. a nw-se alignment of three n-s striking, high-anomaly segments occurs in the east along t h e piedmont between n78'25' and 26'. two clus ters of high anomaly segments occur further east south of n7825'. geological evidence. a narrow graben with carboniferous quartzites, shales and limestones, which is considered to be the eastern margin of t h e tertiary forlandsundet g r a b e n , occurs along t h e western slope of svartfjella t o the strandflat southwest of j ~ r g e n f j e l l e t , keeping a 1.3-1.5 km distance from the coast (ohta 1988). the car boniferous rocks occur as a half-graben in the northern coast of eidembukta. showing an uncon formity in the west a n d a steep fault in t h e east. t h e basal conglomerate locally has a hematite matrix. to the west of the graben occur low-grade metamorphic rocks, observed at scattered exposures along streams under marine terrace deposits and along the western coast (berg e t al. 1993). psammo-pelitic phyllites and quartzites occur in the northern part, striking ca. 330" and dipping moderately t o steeply. showing repe titions by folding. these rocks have a garnet biotite assemblage within the northernmost 3 km from miillerneset (ague & morris 1985). to the south of n78"25', similar phyllites and quartzites a r e exposed along the coast and are associated with some marbles and green phyllites, showing roughly n-s strike. t h e area between two margin faults of the carboniferous rock graben between n78"24' and 26' consists of a marble-bearing phyllite suc cession with steep to vertical dips. t h e same succession occurs t o the east of the graben as south as n78"23' with subvertical dips, suggesting repetition by folding. south of n78'23' occur phyllitic tilloids. meta-sandstones and some mar ble lenses. hrerpretations. intense high magnetic anomaly segments in the southern half, to the west of the carboniferous rock graben, a r e thought t o have been caused by frequent occurrences of green phyllites with magnetite in a marble-quartzite phyllite succession. t h e boundary between this succession and the northern quartzite-phyllite succession without green phyllites could not be drawn by surface mapping d u e t o poor exposure, but the magnetic pattern gives its approximate position a t around n78'26'. t h e elongation trend of the high anomaly segments along the coast in the southern half is surface magnetic anomaly study on the eastern part of the forlandsundet graben 65 subparallel with the observed fold axes, weakly oblique to the trend of the alignment in a 330" direction. this may represent refolded green phyllites in the marble-quartzite-phyllite success ion. an older steep fold limb striking 330" was folded into younger folds with a n-s axial trend. the high anomaly segments between the faults bounding the carboniferous rock graben show a left stepping arrangement which may suggest folds with a n-s axial trend, produced by a sinistral transpressive component of the fault movements. the marble-phyllite succession to the east of the graben has some high anomaly clusters caused by green phyllites. the tilloid succession in the southeast shows a relatively quiet magnetic field. the western marginal fault of the carbon iferous rock graben can locally be recognised as the terminations of high anomaly clusters in the east between 78'25' and 78"26', but it has no magnetic expression along large parts of its sur face trace. the basal conglomerate of the car boniferous succession with a hematite matrix also shows no magnetic anomaly. daudmannsoyra (figs. 4d and 5 d ) magnetic characteristics. four subareas are recognized on the magnetic anomaly map of daudmannsoyra. the western subarea (ws in fig. sd), west of the wilkinsbukta-marstran dodden line and hamnetangen, is characterised by gentle positive anomaly gradients, having a narrow, straight high anomaly zone, ca. 200m wide, with more than 30 nt (local max. 350 nt, not shown in fig. 4d). the middle-western subarea (mws in fig. 5d) extends for ca. 2 km from the east of farmhamna to the south and wedges out to the nw of wil kinsbukta. it shows negative anomalies with gentle gradients. the middle-eastern subarea (mes in fig. 5d) is shown in the middle of fig. 4d, and has many distinctly high anomalies more than 100 nt (local max. 2,50ont, not shown in fig. 4d) with steep gradients, separated by negative fields. the clus ters of high anomalies abruptly terminate, or probably displace dextrally in the sw of venernbreen, along a wnw-ese line. another line of discontinuity of high anomaly segments, but with a sinistral displacement, can be recog nised ca. 2 km east of marstrandodden in the middle of high-anomaly-clustered area. these two lines are located roughly at the positions where later faults have been estimated by the surface mapping (ohta et al. 1992). the eastern subarea (es in fig. 5d) shows wide high and low anomalies with gentle gradients. a wide negative anomaly area in western kinne fjellet (fig. 4d) shows a steep gradient at its western margin, but the over-all shape of this has not been measured. geological evidence. the eastern margin of the tertiary forlandsundet graben in this area is a narrow half-graben filled by carboniferous rocks. the west side of the half-graben is a moderately e-dipping uncomformity, with a basal con glomerate having a hematite matrix. the eastern margin is a steep fault, which extends to the middle of hamnetangen in the north (ohta 1988). mesozoic dolerites are exposed within the car boniferous rock areas, at four localities in western daudmannsoyra and at three localities in hamne tangen (ohta et al. 1992). the area west of the half-graben contains thick marbles and pelitic phyllites, showing repeated folds with steep axial surfaces with strikes of 340 350". this succession has been considered late proterozoic (ohta et al. 1992). a ca. 1 km wide area in the east of farrnhamna and tordenskjoldbukta consists of phyllitic til loids. to the east of the tilloids, a 1 to 3 km wide zone is composed of psammo-pelitic phyllites with many marble layers. west of kinnefjellet and holtedahlvarden (ca. 2 km south of kinnefjellet), another ca. 1 km wide zone consists of phyllites with quartzite layers. this quartzite-phyllite suc cession has a gentle w-dipping structure and underlies widely in the eastern part of daud mannsoyra. the lower part of the marble-phyllite succession and some parts of the quartzite-phyllite succession in the mountains to the east contain green phyllites and metabasic rocks. e.g. weakly metamorphosed gabbros. interpretations. six of the seven localities of the mesozoic dolerites are located in the linear high anomaly zone within the half-graben containing the carboniferous rocks. a gabbro-diabase mass occurs at the isolated magnetic high on the west ern coast of wilkinsbukta, along the eastern mar ginal fault of the half-graben. the dolerites, having high magnetic susceptibility (fig. 2), are the causative rocks of this high anomaly zone. 66 a . a . krasil’seikou et al. small sinistral displacements of this high anomaly zone can be seen at ca. 3 km north of kapp scania and at ca. 1.5 km south of marstrandodden. these may suggest faults formed after the emplacement of the dolerites. the basal conglomerate of the carboniferous with a hematite matrix does not show any magnetic expression. the late proterozoic phyllite-marble suc cession appears as a gentle positive anomaly area of the ws. t h e tilloids and a part of the marble phyllite successions reveal gentle negative anom aly areas in the mws and the mes. a relatively intense negative anomaly area in the north ernmost mws (fig. 4d) can be explained by the presence of a n open synform of thick marbles which have low magnetic susceptibility. distinctly high anomalies i n the m e s can be explained by green phyllites and metabasic rocks. having high magnetic susceptibilities of 100 500 x 1w6 si, intercalated with both marble phyllite and quartzite-phyllite successions. they probably have steep fold structures. these suc cessions are similar to those in s w svartfjell stranda. t h e boundary between these two suc cessions is not distinguishable o n the magnetic anomaly map. open magnetic anomaly patterns with gentle gradients in the es suggest gentle structures of the quartzite-phyllite succession. as observed in the eastern mountains. the green phyllites and metabasic rocks there have small vertical thick nesses d u e to gently dipping structures. the abrupt termination and interruption of the high anomaly clusters in the m e s indicate wnw e s e and ne-sw striking faults. faults in these strikes have been observed in the field, displacing the marginal fault of the half-graben. conclusions three types of rocks from the present area are magnetic with values higher than 40 x si (fig. 2 ) . type 1 rocks are mesozoic dolerites ( o h t a e t a]. 1992). and serpentinites of type 2 and green-brown dolomite of type 3 are affinities of the high-pressure metamorphic suite ( o h t a 1979: teben’kov & korago 1992). green phyllites and metabasic rocks of type 3 are members of the marble-(quartzite)-phyllite succession (calc argillo-volcano formation of hjelle et al. 1979, the alkhornet formation of harland et al. 1979). some belong to the quartzite-phyllite succession (quartzite-shale formation of hjelle et al. 1979, t h e l ~ v l i e b r e e n formation of harland et al. 1979). some a r e intrusive sills and stocks (ohta 1985). t h e occurrences of these highly magnetic rocks coincide well with those of the high magnetic anomaly zones. some subsurface structures and lithologies under the quaternary cover o n the strandflats became evident by the present magnetic survey. sarsgyra: t h r e e high magnetic anomaly zones coincide with the observed faults and the occur rences of the rocks of types 2 and 3. these zones are considered magnetic anomaly expressions of subsurface faults or fault zones. t h e e h a z is superposed by the eastern mar ginal fault of the tertiary forlandsundet graben. some high anomaly segments in this zone show a left-stepping en echelon alignment which suggests a set of synthetic faults produced by a dextral transpressive movement a t a certain stage of fault activities. some abrupt terminations and bends of the high anomaly segments may have been resulted by younger faults after the formation of the n-s and nnw-sse trending faults. k a f f i ~ y r a : probably d u e t o a thick tertiary cover. the middle and western parts of this strand flat show a relatively quiet magnetic field. distinct high anomaly segments occur along the piedmont in the east. t h e n h a z and s h a z coincide with the tertiary-basement boundary, though the boundary is magnetically very weakly expressed between these two zones in the middle of the strandflat. t h e f h a z along t h e eastern piedmont corre sponds to the distribution area of the marble phyllite succession containing green phyllites and metabasic rocks. a fault within the zone is sug gested by a n occurrence of serpentinite. a poss ible continuation of the n h a z t o the f h a z can not b e neglected. suarrfjellstranda: t h e boundary between the marble-(quartzite)-phyllite and t h e quartzite phyllite successions is roughly defined by the dif ference of intensity of high magnetic anomaly segments. t h e graben consists of carboniferous rocks along t h e eastern margin of the for landsundet g r a b e n a r e not expressed by a mag netic anomaly. d a u d m a n n s ~ y r a : mesozoic dolerites show a distinct high anomaly zone from hamnetangen to kapp scania. surface magnetic anomaly study on the eastern part of the forlandsundet graben 67 both marble-phyllite and quartzite-phyllite suc cessions contain green phyllites and metabasic rocks in this area. as these rocks are highly mag netic, the boundary of these successions cannot b e recognised o n t h e magnetic anomaly map. late proterozoic and the tilloid successions show relatively quiet magnetic fields. the half-graben with the carboniferous rocks, which represents the eastern margin of the forlandsundet graben, does not show any specific magnetic signature. sudden truncations and interruptions of the high anomaly clusters suggest later faults. faults with similar strikes were observed cutting the fault along the eastern margin of the half-graben. field occurrences of serpentinites and green brown dolomites along the high-anomaly zones in sarsoyra and kaffioyra suggest that these rocks underly the present surface. they are diagnostic members of the thrust sheets, which consisted mainly of the high-pressure metamorphic rocks in motalafjella (ohta 1979; hirajima e t al. 1988). accordingly, the possibility of a distribution of the high-pressure metamorphic rocks as far north as sarsoyra is suggested. this point will be pre sented further in a separate article (ohta e t al. in prep. 1. acknowledgements. constructive discussions and the kind supply of field data by a . hjelle, norsk polarinstitutt, and j . skilbrei. norges geologiske unders0kelse. are deeply acknowl edged. k. l kleinspehn and w . k. dallmann kindly improved the english of the manuscript. references ague, j . j. & morris, a. p. 1985: metamorphism of the mul lerneset formation, st. jonsfjorden, sv;ilbard. polar res. 3, 9s106. armstrong. h a..nakrem,h. a . &ohta. y . 1986: ordovician conodonts from the bulltinden formation. motalafjella, cen tral-western spitsbergen. polar res. 4 . 17-23. berg, s. g., ohta, y., andresen, a , , maher, h . d.. braathen, a. & dallmann, w. k . 1993: geological map of svalbard 1 : 100.000, sheet b8g, st. jonsfjorden, preliminary edition. norsk polarinstitutt. bernard-griffiths. j . , peucat, j. j . & ohta, y. 1993: age and nature of protoliths in the caledonian blueschist-eclogite complex of western spitsbergen: a combined approach using u-pb, sm-nd and r e e whole-rock systems. lithos 30, 81 90. dallmann, w . k.. andresen, a , , bergh, s. g.. maher. h . d. jr. & ohta. y . 1993: tertiary fold-and-thrust belt of spitsbergen, svalhard. norsk polarinst. m e d d . 128, 1-46. 3 maps. dallmeyer. r . d . , peucat, j. j. & ohta, y . 1990: tec tonothermal chronology within a blueschist-eclogite complex, west-central spitsbergen, svalbard: evidence from 40ar/ 39ar and rh-sr mineral ages. lithos 2 4 . 291-304. gabrielsen, r. h . , klclvjan. 0. s . . haugsbcl. h . , midbee. p. s . , n ~ t t v e d t , a , , rasmussen. e . & skott. p. h . 1992: a structural outline of forlandsundet graben, prim karls for land, svalbard. norsk geol. tidrkrifr 7 2 . 105-120. harland, w. b . , horsfield, w. t . , manby, g . m . & morris. a . p. 1979: a n outline of pre-carboniferous stratigraphy of central western spitsbergen. norsk polarinst. skr. 167, 119 144. hjelle, a . , ohta. y . & winsnes. t . s. 1979: hecla houh rocks of oscar i1 land and prins karls forland, svalbard. n u r d polarinst. skr. 167, 145-169. hirajima, t . , banno, s . , hiroi, y. & ohta, y . 1988: phase petrology of eclogites and related rocks from the motalafjella high-pressure metamorphic complex in spitsbergen (arctic ocean) and its significance. lithos 2 2 , 75-97. kanat. l . & morris, a . p. 1988: a working stratigraphy for central western oscar i1 land, spitsbergen. norsk polarinsr. skr. 190, 1-23. kleinspehn. k. & teyssier. c. 1992: tectonics of the paleogene tertiary basin, spitsbergen; a preliminary report, nursk geol. tidskrifl 7 2 , 94-104. kovaces, l. c. & vogt, p. r. 1982: depth to magnetic source analysis of the arctic region. tectonophysics 8 9 , 255-294. krasil’sfikov. a . a . & kovaleva, g. a . 1976: dokembrijskie litologo-stratigrafiteskie kompleksy zapadnogo poberei’ja spicbergena (precambrian lithologostratigraphic complexes of the western coast of spitsbergen). in: geologija sual‘barda. niiga, leningrad, 6>70. krasil’si-ikov. a . a. & kovaleva, g . a . 1979: precambrian rock stratigraphic units of the west coast of spittbergen. norsk polarinst. skr. 167. 81-88. lepvner, c . , 1992: early tertiary paleostress distribution o n spitsbergen: implication for the tectonic development of the western fold andthrust belt. norsk geol. tidikrift 72.129 135. logapev. a . a . & zacharov, v. p. 1980: magnitorazvedka (magnetic exploration). “nedra”. moskva. 1-295. ohta, y . 1979: blue schists from motalafjella, western spits bergen. norsk polarinstir. skr. 167, 171-217. ohta, y . 1985: geochemistry of pre-cambrian basic igneous rocks between st. jonsfjorden and isfjorden, central western spitsbergen. svalhard. polar res. 3 . 4y-67. ohta. y . 1988: structures of carboniferous strata at tryggh amna and along the southeastern margin of forlandsundet graben. norsk polarinst. rapp. 46. 25-28. ohta, y . . hirajima, t. & hiroi, y . 1986: caledonian high pressure metamorphism in central-western spitsbergen. geol. soc. a m e r . mem. 164, 205-216. ohta, y . , hiroi. y . and hirajima, t . 1984: additional evidence of pre-silurian high-pressure metamorphic rocks in spits bergen. polar res. n . s . , 1 . 215-218. ohta. y., hjelle, a , , andresen. a., dallmann, w. k. 8: salvigsen, 0. 1992: geological map of svalhard 1: 100,000. sheet b9g isfjorden, with description. norsk polarinsr. temakart 16, 1-52. peters. l. j. 1949: the direct approach to magnetic inter pretation and its practical application. geophys. 14,290-320. scrutton, c. t.. horsfield, w . t . & harland. w. b. 1976: silurian fossils from western spitsbergen. geol. mag. 113 ( 6 ) . 519-523. srebnij, s . a , , poplavskij, v. b. & cegarnov. b . l . 1985: struktura matematifeskogo obespetenija avtomatiriroven noj sistemy obrabotki aerogeofizifeskich dannych na es evm (structure of mathematic securing of an automatized system of processing of aerogeographic data on computer 68 a . a . k m s i l ' f f i k o v et a / . primenenie e v m ) i n : prirnrnenie evm dlla resheriilo geo logo-grofiriclieskicli zadacli 0 sibiri (applicurion ofcornpirrrr f o r w l u t i o n of kroloru-reoph?sical p r o b l e m bi siberia) trudy sibirskogo otdelenija a n s s r . novosibirsk. 12-18 (tranaactions of the siberian department of the academv of s c i e n c o of thc ussh) t e b e n ' k m . a . m fi korago. e . a . 1992: litatvenit) z a p a d nogo spicbergena (litvcnitcs of western spitsbergen) i n : zapiski gpesojuzriopu minrralogiteskogo o b f t e s r u a 1,vorrs on the panuriiorial mineralogical sociehl .vo. 2 , leningrad. 6 0 x 4 volk. v. e . . i \ a n o \ . s. s . & simaraev. v n. 1973: hletodika interpretacii aeromagnitnich dannych pri izufenii zemnoj kori na primere issledovani~a sel'fov severnych morcj sssr (methods of interpretation of aeromagnetic data in the study of the terrestrial crust exemplified by an investigation of the shelves of the northern seas of the ussr). " n e d r a " , leningrad. 1-87 wojcik. c . w . 1981: geological observations in the eastern part of forlandsundet g r a b e n between dahlbreen and eng elskbukta. spitsbergen srudra geologica polonica 73,25-35. am. k. 1975: aeromagnetic basement complex mapping north of latitude 67"n. norway norgrs geologiske undersmkelse 316. 351-374.